WO2024156764A1

WO2024156764A1 - Aerosol-generating article with low resistance to draw and aerosol-generating film substrate

Info

Publication number: WO2024156764A1
Application number: PCT/EP2024/051675
Authority: WO
Inventors: Farhang MOHSENI
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2023-01-25
Filing date: 2024-01-24
Publication date: 2024-08-02
Anticipated expiration: 2025-07-25
Also published as: EP4654843A1; CN120640989A; MX2025008405A; KR20250136962A

Abstract

An aerosol-generating article (10) for producing an inhalable aerosol upon heating extends from a mouth end to a distal end and comprises: a rod-shaped aerosol-generating element (12) comprising an aerosol-generating substrate, the aerosol-generating substrate comprising an aerosol-generating film; a downstream section (14) at a location downstream of the aerosol-generating element, the downstream section extending from a downstream end of the aerosol-generating element (10) to the mouth end of the aerosol-generating article (10). The downstream section comprises a hollow section (15) defining a longitudinal cavity providing an unrestricted flow channel. An RTD of the downstream section is less than 25 mm H2O. The aerosol-generating film comprises one or more cellulose based film-forming agents and one or more aerosol formers. The aerosol-generating film has a total aerosol former content of greater than or equal to 46 percent by weight.

Description

AEROSOL-GENERATING ARTICLE WITH LOW RESISTANCE TO DRAW AND AEROSOLGENERATING FILM SUBSTRATE

The present invention relates to an aerosol-generating article comprising an aerosolgenerating substrate and adapted to produce an inhalable aerosol upon heating.

Aerosol-generating articles in which an aerosol-generating substrate, such as a tobaccocontaining substrate, is heated rather than combusted, are known in the art. Typically, in such heated smoking articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

Consumables, in which a solid substrate in the form of a gel or film containing nicotine, that are heated rather than combusted, are known in the art. By way of example, WO 2018/019543 discloses a thermoreversible gel composition, that is, a gel that will become fluid when heated to a melting temperature and will set into a gel again at a gelation temperature. The gel is provided within a housing of a cartridge, and the cartridge can be disposed of and replaced when the gel has been consumed. WO 2020/207733 discloses a consumable comprising a rod of aerosol-generating substrate with a plurality of stacked layers of an aerosol-generating film. In use, the majority of the components of the film may evaporate on heating, leaving minimal residue and allowing for an article that is easier to dispose of and has a reduced environmental impact.

A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosolgenerating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosol-generating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosol-generating substrate. As an alternative, inductively heatable aerosol-generating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosolgenerating substrate have been proposed by WO 2015/176898. A further alternative has been described in WO 2020/115151 , which discloses an aerosol-generating article used in combination with an external heating system comprising one or more heating elements arranged around the periphery of the aerosol-generating article. For example, external heating elements may be provided in the form of flexible heating foils on a dielectric substrate, such as polyimide. External heating could be resistive or inductive. Aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted present a number of challenges that were not encountered with conventional smoking articles. First of all, tobacco-containing substrates are typically heated to significantly lower temperatures compared with the temperatures reached by the combustion front in a conventional cigarette. This may have an impact on nicotine release from the tobacco-containing substrate and nicotine delivery to the consumer. At the same time, if the heating temperature is increased in an attempt to boost nicotine delivery, then the aerosol generated typically needs to be cooled to a greater extent and more rapidly before it reaches the consumer. However, technical solutions that were commonly used for cooling the mainstream smoke in conventional smoking articles, such as the provision of a high filtration efficiency segment at the mouth end of a cigarette, may have undesirable effects in an aerosol-generating article wherein a tobacco-containing substrate is heated rather than combusted, as they may reduce nicotine delivery.

In order to address one or more of the challenges specifically associated with heating rather than combusting an aerosol-generating substrate to generate an aerosol, a number of aerosol-generating articles have been proposed wherein multiple elements are combined, for example in longitudinal alignment, with an aerosol-generating element containing the aerosolgenerating substrate. By way of example, the aerosol-generating element has been combined with a support element to impart improved structural strength to the article, an aerosol-cooling element adapted to lower the temperature of the aerosol, a low-filtration mouthpiece element, etc.

A need is generally felt for aerosol-generating articles that are easy to use and have improved practicality. Additionally, it would be desirable to provide aerosol-generating articles that are easier to manufacture and that may make the whole production chain more sustainable and cost-effective. There is also a need for an aerosol-generating article that is especially suitable for use in combination with an external heating system, and particularly one that has improved aerosol generation and aerosol former delivery. There is further a need to provide such an aerosol-generating article that is easier to dispose of after use or that has reduced environmental impact.

Heating of substrates comprising cellulose based material, in particular hydroxypropylmethyl cellulose (HPMC), to temperatures which are too high, such as higher than 300 degrees Celsius, can lead to a paper off-taste and the generation of formaldehyde. However, heating such substrates to lower temperatures, while reducing the levels of harmful and potentially harmful compounds (HPHCs) generated, also reduces the aerosolization of the aerosol former and nicotine. Additionally, compared to gel substrates which can comprise a relatively high quantity by weight of aerosol former, film substrates comprise a relatively high quantity by weight of cellulose based material to impart structure to the film along with a lower quantity by weight of aerosol former. The lower quantity by weight of aerosol former used in film substrates also reduces the efficiency of delivery of aerosol former and nicotine relative to gel substrates. There is a need to provide an aerosol-generating article comprising a film substrate that allows for efficient delivery of aerosol-former, as well as nicotine.

Therefore, it would be desirable to provide a new and improved aerosol-generating article adapted to satisfy at least one of the needs described above. Further, it would be desirable to provide an aerosol-generating article that allows for efficient delivery of nicotine and/or aerosol former, like glycerine, while maintaining low levels or even reducing levels of HPHCs. Further, it would be desirable to provide one such aerosol-generating article that can be manufactured efficiently and at high speed, preferably with a satisfactory low RTD variability from one article to another.

The present disclosure relates to an aerosol-generating article for producing an inhalable aerosol upon heating, the aerosol-generating article extending from a mouth end to a distal end and comprising an aerosol-generating element. The aerosol-generating element may be in the form of a rod. The aerosol-generating element may comprise an aerosol-generating substrate. The aerosol-generating substrate may comprise an aerosol-generating film. Further, the aerosolgenerating article may comprise a downstream section at a location downstream of the aerosolgenerating element. The downstream section may extend from a downstream end of the aerosolgenerating element to the mouth end of the aerosol-generating article. The downstream section may comprise a hollow section. The hollow section may define a longitudinal cavity providing an unrestricted flow channel. An RTD of the downstream section may be less than 25 mm H2O. The aerosol-generating film may comprise one or more cellulose based film-forming agents and one or more aerosol formers. The aerosol-generating film may have a total aerosol former content of greater than or equal to 46 percent by weight.

According to the present invention there is provided an aerosol-generating article for producing an inhalable aerosol upon heating, the aerosol-generating article extending from a mouth end to a distal end and comprising: a rod-shaped aerosol-generating element comprising an aerosol-generating substrate, the aerosol-generating substrate comprising an aerosolgenerating film; a downstream section at a location downstream of the aerosol-generating element, the downstream section extending from a downstream end of the aerosol-generating element to the mouth end of the aerosol-generating article; wherein the downstream section comprises a hollow section defining a longitudinal cavity providing an unrestricted flow channel; wherein an RTD of the downstream section is less than 25 mm H2O; wherein the aerosolgenerating film comprises one or more cellulose based film-forming agents and one or more aerosol formers, and wherein the aerosol-generating film has a total aerosol former content of greater than or equal to 46 percent by weight . The aerosol-generating article according to the present invention therefore provides a novel-configuration of the section of the aerosol-generating article downstream of the rod of aerosol-generating substrate, which is characterised by having an RTD below 25 mm H2O. This particularly low RTD downstream of the aerosol-generating substrate is provided in combination with an aerosol-generating substrate in the form of a rod comprising an aerosol-generating film.

The provision of a downstream section having a low RTD has the effect that much of the RTD of the aerosol-generating article is provided by the aerosol-generating element (for example, by a rod-shaped aerosol-generating element) itself and optionally by elements located upstream of the aerosol-generating element. The inventors have found that when an aerosol-generating article having an aerosol-generating rod with the geometry described above and one such RTD distribution along the length of the article, it is advantageously possible to optimise the delivery of an aerosol to the consumer, especially if the article is used in combination with an external heating system.

Aerosol delivery may to an extent be impacted by the RTD of the aerosol-generating element itself. This is because the aerosol generated in an upstream portion of the aerosolgenerating element needs first of all to flow through the remainder, downstream portion of the aerosol-generating element. Thus, controlling the geometry of the aerosol-generating element also enables a more effective control of aerosol delivery, and in general aerosol delivery is made more consistent from aerosol-generating article to aerosol-generating article.

This is desirable as it simplifies the construction and operation of both aerosol-generating article and heating device. Further, it has been found that this makes it possible for the substrate to be heated to lower temperatures without prejudice to the quality and amount of the aerosol delivered to the consumer.

In addition, as the provision of a low RTD downstream of the aerosol-generating rodshaped element may be achieved by providing a hollow element downstream of the aerosolgenerating rod-shaped element, a substantially empty volume is provided within the article wherein nucleation and growth of aerosol particles is favoured, whilst RTD is substantially eliminated. This may further contribute to enhancing aerosol generation and delivery compared with existing articles.

In accordance with the present invention there is provided an aerosol-generating article for generating an inhalable aerosol upon heating. The aerosol-generating article comprises an element comprising an aerosol-generating substrate.

The term “aerosol-generating article” is used herein to denote an article wherein an aerosol-generating substrate is heated to produce and deliver an inhalable aerosol to a consumer. As used herein, the term “aerosol-generating substrate” denotes a substrate capable of releasing volatile compounds upon heating to generate an aerosol. The aerosol-generating articles of the present invention comprise aerosol-generating substrates comprising, or in the form of, aerosol-generating films. Such substrates are designed to be heated to relatively low temperatures, that is to say, temperatures less than approximately 300 degrees Celsius, to minimise levels of formaldehyde generated and to avoid paper off-taste. Although heating substrates such as aerosol-generating films to lower temperatures reduces the levels of HPHCs generated, it also reduces the aerosolization of the aerosol former and nicotine. Additionally, relative to gel substrates, aerosol-generating films comprise a relatively high quantity by weight of cellulose-based material to impart structure to the film along with a lower quantity by weight of aerosol former. The lower quantity by weight of aerosol former reduces the efficiency of delivery of aerosol former and nicotine in film substrates relative to gel substrates. The aerosolgenerating articles of the present invention comprising aerosol-generating film substrates allow for efficient delivery of aerosol former as well as nicotine to the consumer by virtue of their relatively lower filtration and low RTD, i.e. less than about 25 millimetres H2O, of the downstream section, compared to conventional aerosol-generating articles.

A conventional cigarette is lit when a user applies a flame to one end of the cigarette and draws air through the other end. The localised heat provided by the flame and the oxygen in the air drawn through the cigarette causes the end of the cigarette to ignite, and the resulting combustion generates an inhalable smoke. By contrast, in heated aerosol-generating articles, an aerosol is generated by heating a flavour generating substrate, such as tobacco. Known heated aerosol-generating articles include, for example, electrically heated aerosol-generating articles and aerosol-generating articles in which an aerosol is generated by the transfer of heat from a combustible fuel element or heat source to a physically separate aerosol forming material. For example, aerosol-generating articles according to the invention find particular application in aerosol-generating systems comprising an electrically heated aerosol-generating device having an internal heater blade which is adapted to be inserted into the rod of aerosol-generating substrate. Aerosol-generating articles of this type are described in the prior art, for example, in EP 0822670.

As used herein, the term “aerosol-generating device” refers to a device comprising a heater element that interacts with the aerosol-generating substrate of the aerosol-generating article to generate an aerosol. During use, volatile compounds are released from the aerosol-generating film by heat transfer and entrained in air drawn through the aerosol-generating article. As the released compounds cool they condense to form an aerosol that is inhaled by the consumer.

The aerosol-generating element may be in the form of a rod comprising or made of the aerosol-generating substrate. As used herein with reference to the present invention, the term “rod” is used to denote a generally cylindrical element of substantially circular, oval or elliptical cross-section. As used herein, the term “longitudinal” refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream and downstream ends of the aerosol-generating article. As used herein, the terms “upstream” and “downstream” describe the relative positions of elements, or portions of elements, of the aerosolgenerating article in relation to the direction in which the aerosol is transported through the aerosol-generating article during use.

As used herein, the term “upstream end of the aerosol-generating article” refers to the distal end of the aerosol-generating article.

As used herein, the term “downstream end of the aerosol-generating article” refers to the mouth end of the aerosol-generating article.

During use, air is drawn through the aerosol-generating article in the longitudinal direction. The term “transverse” refers to the direction that is perpendicular to the longitudinal axis. Any reference to the “cross-section” of the aerosol-generating article or a component of the aerosolgenerating article refers to the transverse cross-section unless stated otherwise.

The term “length” denotes the dimension of a component of the aerosol-generating article in the longitudinal direction. For example, it may be used to denote the dimension of the rod or of the elongate tubular elements in the longitudinal direction.

As used herein, the term “film” is used to describe a solid laminar element having a thickness that is less than the width or length thereof.

The film may be self-supporting. In other words, a film may have cohesion and mechanical properties such that the film, even if obtained by casting a film-forming formulation on a support surface, can be separated from the support surface.

Alternatively, the film may be disposed on a support or sandwiched between other materials. This may enhance the mechanical stability of the film. The “thickness” of the aerosolgenerating film of aerosol-generating articles according to the invention corresponds to the minimum distance measured between opposite, substantially parallel surfaces of a film.

Unless otherwise specified, the resistance to draw (RTD) of a component or the aerosolgenerating article is measured in accordance with ISO 6565-2015. The RTD refers the pressure required to force air through the full length of a component. The terms “pressure drop” or “draw resistance” of a component or article may also refer to the “resistance to draw”. Such terms generally refer to the measurements in accordance with ISO 6565-2015 and are normally carried out at under test at a volumetric flow rate of about 17.5 millilitres per second at the output or downstream end of the measured component at a temperature of about 22 degrees Celsius, a pressure of about 101 kPa (about 760 Torr) and a relative humidity of about 60%.

The aerosol-generating article further comprises a downstream section at a location downstream of the rod of aerosol-generating substrate. As will become apparent from the following description of different embodiments of the aerosol-generating article of the invention, the downstream section may comprise one or more downstream elements. The downstream section comprises a hollow section, and optionally, a mouthpiece section. The mouthpiece section comprises one or more mouthpiece filter segments. The mouthpiece section extends from the upstream end of the most upstream mouthpiece filter segment to the mouth end of the aerosolgenerating article.

The downstream section comprises a hollow section defining a longitudinal cavity providing an unrestricted flow channel. In one embodiment, the downstream section may comprise a hollow section between the mouth end of the aerosol-generating article and the aerosol-generating element, the hollow section extending all the way to the mouth end of the aerosol-generating article. In another embodiment, the downstream section may comprise a hollow section between the aerosol-generating element and a mouthpiece section. The hollow section may comprise a hollow tubular element.

As used herein, the term “hollow tubular segment” or “hollow tubular element” is used to denote a generally elongate element defining a lumen or airflow passage along a longitudinal axis thereof. In particular, the term “tubular” will be used in the following with reference to an element or segment having a substantially cylindrical cross-section and defining at least one airflow conduit establishing an uninterrupted fluid communication between an upstream end of the tubular element or segment and a downstream end of the tubular element or segment. However, it will be understood that alternative geometries (for example, alternative cross-sectional shapes) of the tubular element or segment may be possible.

As used herein, the term “elongate” means that an element has a length dimension that is greater than its width dimension or diameter dimension, for example twice or more its width dimension or its diameter dimension.

In the context of the present invention a hollow tubular segment or hollow tubular element provides an unrestricted flow channel. This means that the hollow tubular segment or hollow tubular element provides a negligible level of resistance to draw (RTD). The term “negligible level of RTD” is used to describe an RTD of less than 1 mm H2O per 10 millimetres of length of the hollow tubular segment or hollow tubular element, preferably less than 0.4 mm H2O per 10 millimetres of length of the hollow tubular segment or hollow tubular element, more preferably less than 0.1 mm H2O per 10 millimetres of length of the hollow tubular segment or hollow tubular element.

The flow channel should therefore be free from any components that would obstruct the flow of air in a longitudinal direction. Preferably, the flow channel is substantially empty.

In the present specification, a “hollow tubular segment” or “hollow tubular element” may also be referred to as a “hollow tube” or a “hollow tube segment”. In some embodiments, the aerosol-generating article may comprise a ventilation zone at a location along the downstream section. In more detail, the aerosol-generating article may comprise a ventilation zone at a location along the hollow tubular element. As such, fluid communication is established between the flow channel internally defined by the hollow tubular element and the outer environment.

The aerosol-generating article may further comprise an upstream section at a location upstream of the rod of aerosol-generating substrate. The upstream section may comprise one or more upstream elements. In some embodiments, the upstream section may comprise an upstream element arranged immediately upstream of the aerosol-generating element.

As described briefly above, an aerosol-generating article in accordance with the present invention comprises an element comprising an aerosol-generating substrate.

In some embodiments, the aerosol-generating element may be provided in the form of a rod comprising the aerosol-generating substrate. By way of example, the aerosol-generating element may comprise a rod of aerosol-generating substrate circumscribed by a wrapper.

The element comprising the aerosol-generating substrate may have a length of at least about 5 millimetres. Preferably, the element comprising the aerosol-generating substrate has a length of at least about 7 millimetres. More preferably, the element comprising the aerosolgenerating substrate has a length of at least about 10 millimetres. In particularly preferred embodiments, the element comprising the aerosol-generating substrate has a length of at least about 12 millimetres.

The element comprising the aerosol-generating substrate may have a length of up to about 80 millimetres. Preferably, the element comprising the aerosol-generating substrate has a length of less than or equal to about 65 millimetres. More preferably, the element comprising the aerosol-generating substrate has a length of less than or equal to about 60 millimetres. Even more preferably, the element comprising the aerosol-generating substrate has a length of less than or equal to about 55 millimetres.

In particularly preferred embodiments, the element comprising the aerosol-generating substrate has a length of less than or equal to about 50 millimetres, more preferably less than or equal to about 35 millimetres, even more preferably less than or equal to about 25 millimetres. In particularly preferred embodiments, the element comprising the aerosol-generating substrate has a length of less than or equal to about 20 millimetres or even less than or equal to about 15 millimetres.

In some embodiments, the element comprising the aerosol-generating substrate has a length from about 5 millimetres to about 60 millimetres, preferably from about 6 millimetres to about 60 millimetres, more preferably from about 7 millimetres to about 60 millimetres, even more preferably from about 10 millimetres to about 60 millimetres, most preferably from about 12 millimetres to about 60 millimetres. In other embodiments, the element comprising the aerosolgenerating substrate has a length from about 5 millimetres to about 55 millimetres, preferably from about 6 millimetres to about 55 millimetres, more preferably from about 7 millimetres to about 55 millimetres, even more preferably from about 10 millimetres to about 55 millimetres, most preferably from about 12 millimetres to about 55 millimetres. In further embodiments, the element comprising the aerosol-generating substrate has a length from about 5 millimetres to about 50 millimetres, preferably from about 6 millimetres to about 50 millimetres, more preferably from about 7 millimetres to about 50 millimetres, even more preferably from about 10 millimetres to about 50 millimetres, most preferably from about 12 millimetres to about 50 millimetres.

In some particularly preferred embodiments, the element comprising the aerosolgenerating substrate has a length from about 5 millimetres to about 30 millimetres, preferably from about 6 millimetres to about 30 millimetres, more preferably from about 7 millimetres to about 30 millimetres, even more preferably from about 10 millimetres to about 30 millimetres. In other particularly preferred embodiments, the element comprising the aerosol-generating substrate has a length from about 5 millimetres to about 20 millimetres, preferably from about 6 millimetres to about 20 millimetres, more preferably from about 7 millimetres to about 20 millimetres, even more preferably from about 10 millimetres to about 20 millimetres. In further particularly preferred embodiments, the element comprising the aerosol-generating substrate has a length from about 5 millimetres to about 15 millimetres, preferably from about 7 millimetres to about 20 millimetres, more preferably from about 9 millimetres to about 16 millimetres, even more preferably from about 10 millimetres to about 15 millimetres.

A rod-shaped element comprising the aerosol-generating substrate preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article.

Preferably, the element comprising the aerosol-generating substrate has an external diameter of at least about 5 millimetres. More preferably, the element comprising the aerosolgenerating substrate has an external diameter of at least about 6 millimetres. Even more preferably, the element comprising the aerosol-generating substrate has an external diameter of at least about 7 millimetres.

The element comprising the aerosol-generating substrate preferably has an external diameter of less than or equal to about 12 millimetres. More preferably, the element comprising the aerosol-generating substrate has an external diameter of less than or equal to about 10 millimetres. Even more preferably, the element comprising the aerosol-generating substrate has an external diameter of less than or equal to about 8 millimetres.

In general, it has been observed that the smaller the diameter of a rod-shaped element comprising the aerosol-generating substrate, the lower the temperature that is required to raise a core temperature of the aerosol-generating element such that sufficient amounts of vaporizable species are released from the aerosol-generating substrate to form a desired amount of aerosol. At the same time, without wishing to be bound by theory, it is understood that a smaller diameter of the rod-shaped element comprising the aerosol-generating substrate allows for a faster penetration of heat supplied to the aerosol-generating article into the entire volume of aerosolforming substrate. Nevertheless, where the diameter of the rod-shaped element comprising the aerosol-generating substrate is too small, a volume-to-surface ratio of the aerosol-generating substrate becomes less favourable, as the amount of available aerosol-forming substrate diminishes.

A diameter of the rod-shaped element comprising the aerosol-generating substrate falling within the ranges described herein is particularly advantageous in terms of a balance between energy consumption and aerosol delivery. This advantage is felt in particular when an aerosolgenerating article comprising a rod comprising the aerosol-generating substrate having a diameter as described herein is used in combination with an external heater arranged around the periphery of the aerosol-generating article. Under such operating conditions, it has been observed that less thermal energy is required to achieve a sufficiently high temperature at the core of the rod comprising the aerosol-generating substrate and, in general, at the core of the article. Thus, when operating at lower temperatures, a desired target temperature at the core of the aerosol-generating substrate may be achieved within a desirably reduced time frame and by a lower energy consumption.

In some embodiments, the element comprising the aerosol-generating substrate has an external diameter from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In other embodiments, the element comprising the aerosol-generating substrate has an external diameter from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres. In further embodiments, the element comprising the aerosol-generating substrate has an external diameter from about 5 millimetres to about 8 millimetres, preferably from about 6 millimetres to about 8 millimetres, more preferably from about 7 millimetres to about 8 millimetres.

In particularly preferred embodiments, the element comprising the aerosol-generating substrate has an external diameter of less than about 7.5 millimetres. By way of example, the element comprising the aerosol-generating substrate may an external diameter of about 7.2 millimetres.

A length to diameter ratio of the aerosol-generating element is at least about 0.50. Preferably, a length to diameter ratio of the aerosol-generating element is at least about 0.75. More preferably, a length to diameter ratio of the aerosol-generating element is at least about 1.00. Even more preferably, a length to diameter ratio of the aerosol-generating element is at least about 1.25.

A length to diameter ratio of the aerosol-generating element is less than or equal to about 3.00. Preferably, a length to diameter ratio of the aerosol-generating element is less than or equal to about 2.75. More preferably, a length to diameter ratio of the aerosol-generating element is less than or equal to about 2.50. Even more preferably, a length to diameter ratio of the aerosolgenerating element is less than or equal to about 2.25.

In more detail, in aerosol-generating articles in accordance with the present invention a length to diameter ratio of the aerosol-generating element is from about 0.50 to about 3.00.

Preferably, a length to diameter ratio of the aerosol-generating element is from about 0.75 to about 3.00. More preferably, a length to diameter ratio of the aerosol-generating element is from about 1 .00 to about 3.00. Even more preferably, a length to diameter ratio of the aerosolgenerating element is from about 1.25 to about 3.00.

In other embodiments, a length to diameter ratio of the aerosol-generating element may be from about 0.50 to about 2.75. Preferably, a length to diameter ratio of the aerosol-generating element is from about 0.75 to about 2.75. More preferably, a length to diameter ratio of the aerosol-generating element is from about 1.00 to about 2.75. Even more preferably, a length to diameter ratio of the aerosol-generating element is from about 1.25 to about 2.75.

In further embodiments, a length to diameter ratio of the aerosol-generating element may be from about 0.50 to about 2.50. Preferably, a length to diameter ratio of the aerosol-generating element is from about 0.75 to about 2.50. More preferably, a length to diameter ratio of the aerosol-generating element is from about 1 .00 to about 2.50. Even more preferably, a length to diameter ratio of the aerosol-generating element is from about 1.25 to about 2.50.

In yet further embodiments, a length to diameter ratio of the aerosol-generating element may be from about 0.50 to about 2.25. Preferably, a length to diameter ratio of the aerosolgenerating element is from about 0.75 to about 2.25. More preferably, a length to diameter ratio of the aerosol-generating element is from about 1.00 to about 2.25. Even more preferably, a length to diameter ratio of the aerosol-generating element is from about 1.25 to about 2.25.

In particularly preferred embodiments, a length to diameter ratio of the aerosol-generating element may be at least about 1.30, more preferably about 1.40, even more preferably about 1.50.

In particularly preferred embodiments, a length to diameter ratio of the aerosol-generating element may be less than or equal to about 2.00, more preferably less than or equal to about 1.90, even more preferably less than or equal to about 1.80.

In some embodiments, a length to diameter ratio of the aerosol-generating element is preferably from about 1.30 to about 2.00, more preferably from about 1.40 to about 2.00, even more preferably from about 1.50 to about 2.00. In other embodiments, a length to diameter ratio of the aerosol-generating element is preferably from about 1.30 to about 1.90, more preferably from about 1.40 to about 1.70, even more preferably from about 1.50 to about 1.90. In further embodiments, a length to diameter ratio of the aerosol-generating element is preferably from about 1.30 to about 1.80, more preferably from about 1.40 to about 1.80, even more preferably from about 1.50 to about 1.80.

A ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article may be at least about 0.10. Preferably, a ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article is at least about 0.15. More preferably, a ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article is at least about 0.20. Even more preferably, a ratio between the length of the aerosol-generating element and an overall length of the aerosolgenerating article is at least about 0.25.

In general, a ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article may be less than or equal to about 0.60. Preferably, a ratio between the length of the aerosol-generating element and an overall length of the aerosolgenerating article is less than or equal to about 0.50. More preferably, a ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article is less than or equal to about 0.45. Even more preferably, a ratio between the length of the aerosolgenerating element and an overall length of the aerosol-generating article is less than or equal to about 0.40. In particularly preferred embodiments, a ratio between the length of the aerosolgenerating element and an overall length of the aerosol-generating article is less than or equal to about 0.35, and most preferably less than or equal to about 0.30.

In some embodiments, a ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article is from about 0.10 to about 0.45, preferably from about 0.15 to about 0.45, more preferably from about 0.20 to about 0.45, even more preferably from about 0.25 to about 0.45. In other embodiments, a ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article is from about 0.10 to about 0.40, preferably from about 0.15 to about 0.40, more preferably from about 0.20 to about 0.40, even more preferably from about 0.25 to about 0.40. In further embodiments, a ratio between the length of the aerosol-generating element and an overall length of the aerosolgenerating article is from about 0.10 to about 0.35, preferably from about 0.15 to about 0.35, more preferably from about 0.20 to about 0.35, even more preferably from about 0.25 to about 0.35. In yet further embodiments, a ratio between the length of the aerosol-generating element and an overall length of the aerosol-generating article is from about 0.10 to about 0.30, preferably from about 0.15 to about 0.30, more preferably from about 0.20 to about 0.30, even more preferably from about 0.25 to about 0.30.

In a particularly preferred embodiment, a ratio between the length of the aerosolgenerating element and an overall length of an aerosol-generating article is 0.27.

Preferably, the aerosol-generating element comprises a rod-shaped element comprising aerosol-generating substrate that has a substantially uniform cross-section along the length of the element. Particularly preferably, the rod-shaped element comprising aerosol-generating substrate has a substantially circular cross-section.

As will be described in greater detail below, an aerosol-generating article in accordance with the present invention comprises a downstream section comprising a hollow section. The downstream section may extend from the downstream end of the aerosol-generating element to the mouth end of the aerosol-generating article.

In the aerosol-generating article according to the present invention, the downstream section comprises a hollow section and, optionally, a mouthpiece section. The hollow section defines a longitudinal cavity providing an unrestricted flow channel. The hollow section may comprise a first hollow tubular element defining the longitudinal cavity providing the unrestricted flow channel. The first hollow tubular element may be immediately downstream of the aerosolgenerating element and abut the downstream end of the aerosol-generating element. The hollow section may comprise one or more hollow tubular elements defining the longitudinal cavity providing the unrestricted flow channel. The hollow section, the first hollow tubular element, or the one or more hollow tubular elements may extend all the way from the downstream end of the aerosol-generating element to the mouth end of the aerosol-generating article. Alternatively, a mouthpiece section may be present, such that the hollow section is an intermediate hollow section between the aerosol-generating element and the mouthpiece section.

The hollow section may further comprise a second hollow tubular element. The hollow section may comprise a first and second hollow tubular element defining the longitudinal cavity providing the unrestricted flow channel.. The first hollow tubular element may be immediately downstream of the aerosol-generating element and abut the aerosol-generating element. The support element may be immediately downstream of the aerosol-generating element and abut the aerosol-generating element. An aerosol-cooling element may comprise or be in the form of the second hollow tubular element. The second hollow tubular element may be immediately downstream of the first hollow tubular element and abut the first hollow tubular element. The aerosol cooling element may be immediately downstream of the support element and abut the support element.

If a mouthpiece section is present, the hollow section is an intermediate hollow section between the mouthpiece section and the aerosol-generating element. The mouthpiece section, when present, extends from the upstream end of the most upstream mouthpiece filter segment to a mouth end of the aerosol-generating article. The mouthpiece section may be downstream of a hollow tubular element, or the one or more hollow tubular elements. The mouthpiece section may abut a hollow tubular element. The mouthpiece section may be located downstream of both the first hollow tubular element or support element and second hollow tubular element or the aerosol-cooling element. Particularly preferably, the mouthpiece section may be located immediately downstream of the second hollow tubular element or aerosol-cooling element. By way of example, the upstream end of the mouthpiece filter segment may abut the downstream end of the aerosol-cooling element.

A length L1 of the downstream section may be defined as the distance between the downstream end of the aerosol-generating element to the mouth end of the aerosol-generating article. The hollow section may extend from the downstream end of the aerosol-generating element to the upstream end of a mouthpiece section, or, if a mouthpiece section is not present, from the downstream end of the aerosol-generating element to the mouth end of the aerosolgenerating article. A length L2 of the hollow section may be defined as the distance from the upstream end of the most upstream hollow tubular element comprising the hollow section to the downstream end of the most downstream hollow tubular element comprising the hollow section. A hollow tubular element may be located immediately downstream of the aerosol-generating element and may abut the aerosol-generating element. A length L2 of the hollow section may be defined as the distance between the downstream end of the aerosol-generating element to the upstream end of a mouthpiece section, or, if a mouthpiece section is not present, from the downstream end of the aerosol-generating element to the mouth end of the aerosol-generating article. In embodiments in which L1 equals L2, the hollow section may extend all the way to the mouth end of the aerosol-generating article. In embodiments in which L2 is less than L1, the hollow section may extend from the downstream end of the aerosol-generating element to the upstream end of a mouthpiece section.

The downstream section may have any length L1. The downstream section may have a length of at least about 10 millimetres. For example, the downstream section may have a length of at least about 15 millimetres, at least about 20 millimetres, at least about 25 millimetres, or at least about 30 millimetres.

The provision of a downstream section having a length greater than the values set out above may advantageously provide space for the aerosol to cool and condense before reaching the consumer. This may also ensure a user is spaced apart from the heating element when the aerosol-generating article is used in conjunction with an aerosol-generating device.

The downstream section may have a length of no more than about 60 millimetres. For example, the downstream section may have a length of no more than about 50 millimetres, no more than about 55 millimetres, no more than about 40 millimetres, or no more than about 35 millimetres.

The downstream section may have a length of between about 10 millimetres and about 60 millimetres, between about 15 millimetres and about 50 millimetres, between about 20 millimetres and about 55 millimetres, between about 25 millimetres and about 40 millimetres, or between about 27 millimetres and about 35 millimetres. For example, the downstream section may have a length of about 33 millimetres, or a length of about 28 millimetres.

A ratio between the length of the downstream section and the length of the element comprising aerosol-generating substrate may be from about 1.00 to about 4.50.

Preferably, a ratio between the length of the downstream section and the length of the aerosol-generating element is at least about 1 .50, more preferably at least about 2.00, even more preferably at least about 2.30. In preferred embodiments, a ratio between the length of the downstream section and the length of the aerosol-generating element is less than about 4.00, more preferably less than about 3.50, even more preferably less than about 3.00.

In some embodiments, a ratio between the length of the downstream section and the length of the aerosol-generating element is from about 1.50 to about 4.00, preferably from about 2.00 to about 3.50, more preferably from about 2.30 to about 3.00.

In a particularly preferred embodiment, a ratio between the length of the downstream section and the length of the aerosol-generating element is about 2.33. In another embodiment, a ratio between the length of the downstream section and the length of the aerosol-generating element is about 2.75.

A ratio between the length of the downstream section and the overall length of the aerosolgenerating article may be from about 0.10 to about 0.90.

Preferably, a ratio between the length of the downstream section and the overall length of the aerosol-generating article is at least about 0.25, more preferably at least about 0.50. A ratio between the length of the downstream section and the overall length of the aerosol-generating article is preferably less than about 0.85, more preferably less than about 0.90.

In some embodiments, a ratio between the length of the downstream section and the overall length of the aerosol-generating article is preferably from about 0.25 to about 0.90, more preferably from about 0.50 to about 0.90. In some embodiments, a ratio between the length of the downstream section and the overall length of the aerosol-generating article is preferably from about 0.25 to about 0.85, more preferably from about 0.50 to about 0.85.

In a particularly preferred embodiment, a ratio between the length of the downstream section and the overall length of the aerosol-generating article is about 0.62. In another embodiment, a ratio between the length of the downstream section and the overall length of the aerosol-generating article is about 0.73. The length of the downstream section may be composed of the sum of the lengths of the individual components forming the downstream section.

As described briefly above, in aerosol-generating articles in accordance with the present invention, an RTD of the downstream section is less than about 25 mm H2O. Preferably, an RTD of the downstream section may be less than or equal to about 15 mm H2O, or less than or equal to about 10 mm H2O, or less than or equal to about 1 mm H2O, or about 0 mm H2O. An RTD of the downstream section may be greater than about 10 mm H2O, or between about 10 mm H2O and 25 mm H2O, even more preferably between about 10 mm H2O and 15 mm H2O. The RTD of the downstream section will also be discussed in greater detail below.

The downstream section may comprise an unobstructed airflow pathway from the downstream end of the aerosol-generating substrate to the downstream end of the downstream section.

The unobstructed airflow pathway from the downstream end of the aerosol-generating substrate to the downstream end of the downstream section has a minimum diameter of about 0.5 millimetres. For example the unobstructed airflow pathway may have a minimum diameter of 1 millimetre, 2 millimetres, 3 millimetres or 5 millimetres.

The downstream section may comprise a hollow section. The hollow section may comprise a hollow tube element, or one or more hollow tube elements. The hollow section substantially does not contribute to the RTD of the downstream section. The hollow tube elements substantially do not contribute to the RTD of the downstream section.

As described below, the mouthpiece section may contribute minimally to the RTD of the downstream section.

The provision of a hollow tube element may advantageously provide a desired overall length of the aerosol-generating article without increasing the resistance to draw unacceptably.

The hollow section may extend from the downstream end of the downstream section to the upstream end of the downstream section. In other words, the entire length of the downstream section may be accounted for by the hollow section. That is to say, the length of the downstream section L1 is equal to the length of the hollow section L2 according to the definition above. Where this is the case, it will be appreciated that the lengths and length ratios set out above in relation to the downstream section are equally applicable to the length of the hollow section.

The hollow section may have any length L2. The hollow section may have a length of at least about 10 millimetres. For example, the hollow section may have a length of at least about 15 millimetres, at least about 20 millimetres, at least about 25 millimetres, or at least about 30 millimetres.

The provision of a hollow section having a length greater than the values set out above may advantageously provide space for the aerosol to cool and condense before reaching the consumer. This may also ensure a user is spaced apart from the heating element when the aerosol-generating article is used in conjunction with an aerosol-generating device.

The hollow section may have a length of no more than about 60 millimetres. For example, the hollow section may have a length of no more than about 50 millimetres, no more than about 55 millimetres, no more than about 40 millimetres, or no more than about 35 millimetres.

The hollow section may have a length of between about 10 millimetres and about 60 millimetres, between about 15 millimetres and about 50 millimetres, between about 15 millimetres and about 55 millimetres, between about 15 millimetres and about 40 millimetres, or between about 27 millimetres and about 35 millimetres. For example, the hollow section may have a length of about 16 millimetres, about 28 millimetres or about 33 millimetres.

The hollow section may extend from the downstream end of the aerosol-generating element all the way to the mouth end of the aerosol-generating article, and have a length of at least 25 millimetres.

A ratio between the length of the hollow section and the length of downstream section may be from about 0.30 to about 1.00.

Preferably, a ratio between the length of the hollow section and the length of the downstream is at least about 0.40, more preferably at least about 0.50. A ratio between the length of the hollow section and the length of the downstream section may be about 1.00.

In some embodiments, a ratio between the length of the hollow section and the length of the downstream section is preferably from about 0.40 to about 1.00, more preferably from about 0.50 to about 1.00.

In a particularly preferred embodiment, a ratio between the length of the hollow section and the length of the downstream section is about 0.57. In another particularly preferred embodiment, a ratio between the length of the hollow section and the length of the downstream section is about 1.00.

A ratio between the length of the hollow section and the length of the element comprising aerosol-generating substrate may be from about 1.00 to about 4.50.

Preferably, a ratio between the length of the hollow section and the length of the aerosolgenerating element is at least about 1.10, more preferably at least about 1.20, even more preferably at least about 1.30. In preferred embodiments, a ratio between the length of the hollow section and the length of the aerosol-generating element is less than about 4.00, more preferably less than about 3.50, even more preferably less than about 3.00.

In some embodiments, a ratio between the length of the hollow section and the length of the aerosol-generating element is from about 1.10 to about 4.00, preferably from about 1.20 to about 3.50, more preferably from about 1.30 to about 3.00. In a particularly preferred embodiment, a ratio between the length of the hollow section and the length of the aerosol-generating element is about 1.33. In a particularly preferred embodiment, a ratio between the length of the hollow section and the length of the aerosolgenerating element is about 2.33. In a particularly preferred embodiment, a ratio between the length of the hollow section and the length of the aerosol-generating element is about 2.75.

A ratio between the length of the hollow section and the overall length of the aerosolgenerating article may be from about 0.10 to about 0.90.

Preferably, a ratio between the length of the hollow section and the overall length of the aerosol-generating article is at least about 0.25, more preferably at least about 0.30. A ratio between the length of the downstream section and the overall length of the aerosol-generating article is preferably less than about 0.80, more preferably less than about 0.90.

In some embodiments, a ratio between the length of the hollow section and the overall length of the aerosol-generating article is preferably from about 0.10 to about 0.90, more preferably from about 0.10 to about 0.80. In some embodiments, a ratio between the length of the hollow section and the overall length of the aerosol-generating article is preferably from about 0.25 to about 0.90, more preferably from about 0.25 to about 0.80.

In a particularly preferred embodiment, a ratio between the length of the hollow section and the overall length of the aerosol-generating article is about 0.36. In a particularly preferred embodiment, a ratio between the length of the hollow section and the overall length of the aerosolgenerating article is about 0.62. In a particularly preferred embodiment, a ratio between the length of the hollow section and the overall length of the aerosol-generating article is about 0.75.

The hollow section may comprise a hollow tubular element defining a longitudinal cavity providing an unrestricted flow channel.

The hollow tube may extend from the downstream end of the downstream section to the upstream end of the downstream section. In other words, the entire length of the downstream section may be accounted for by the hollow tube element. A ratio of the length of the hollow tube element to the length of the downstream section may be about 1 .00. Where this is the case, it will be appreciated that the lengths and length ratios set out above in relation to the downstream section are equally applicable to the length of the hollow tube element.

The hollow tube may extend from the downstream end of the hollow section to the upstream end of the hollow section. In other words, the entire length of the hollow section may be accounted for by the hollow tube element. A ratio of the length of the hollow tube element to the length of the hollow section may be about 1 .00. Where this is the case, it will be appreciated that the lengths and length ratios set out in relation to the hollow section are equally applicable to the length of the hollow tube element.

The hollow tube element may abut the downstream end of the aerosol-generating article. The hollow tube element may be spaced apart from the downstream end of the aerosolgenerating article. Where this is the case, there may be an empty space between the downstream end of the aerosol-generating substrate and the upstream end of the hollow tube element.

The hollow tube element may have an internal diameter. The hollow tube element may have a constant internal diameter along the length of the hollow tube element. The internal diameter of the hollow tube element may vary along the length of the hollow tube element.

The hollow tube element may have an internal diameter of at least about 2 millimetres. For example, the hollow tube element may have an internal diameter of at least about 4 millimetres, at least about 5 millimetres, or at least about 7 millimetres.

The provision of a hollow tube element having an internal diameter as set out above may advantageously provide sufficient rigidity and strength to the hollow tube element.

The hollow tube element may have an internal diameter of no more than about 10 millimetres. For example, the hollow tube element may have an internal diameter of no more than about 9 millimetres, no more than about 8 millimetres, or no more than about 7.5 millimetres.

The provision of a hollow tube element having an internal diameter as set out above may advantageously reduce the resistance to draw of the hollow tubular element.

The hollow tube element may have an internal diameter of between about 2 millimetres and about 10 millimetres, between about 4 millimetres and about 9 millimetres, between about 5 millimetres and about 8 millimetres, or between about 7 millimetres and about 7.5 millimetres.

The hollow tube element may have an internal diameter of about 7.1 millimetres.

The ratio between an internal diameter of the hollow tube element and the external diameter of the hollow tube element may be at least about 0.80. For example, the ratio between an internal diameter of the hollow tube element and the external diameter of the hollow tube element may be at least about 0.85, at least about 0.90, or at least about 0.95.

The ratio between an internal diameter of the hollow tube element and the external diameter of the hollow tube element may be no more than about 0.99. For example, the ratio between an internal diameter of the hollow tube element and the external diameter of the hollow tube element may be no more than about 0.98.

The ratio between an internal diameter of the hollow tube element and the external diameter of the hollow tube element may be about 0.97.

The provision of relatively large internal diameter may advantageously reduce the resistance to draw of the hollow tubular element.

The lumen of the hollow tubular element may have any cross sectional shape. The lumen of the hollow tubular element may have a circular cross sectional shape.

The hollow tubular element may be formed from any material. For example, the hollow tube may comprise cellulose acetate tow. Where the hollow tubular element comprises cellulose acetate tow, the hollow tubular element may have a thickness of between about 0.1 millimetre and about 1 millimetre. The hollow tubular element may have a thickness of about 0.5 millimetres.

Where the hollow tubular element comprises cellulose acetate tow, the cellulose acetate tow may have a denier per filament of between about 2 and about 4 and a total denier of between about 25 and about 40.

The hollow tubular element may comprise paper. The hollow tubular element may comprise at least one layer of paper. The paper may be very rigid paper. The paper may be crimped paper, such as crimped heat resistant paper or crimped parchment paper. The paper may be cardboard. The hollow tabular element may be paper tube. The hollow tubular element may be a tube formed from spirally wound paper. The hollow tubular element may be formed from a plurality of layers of the paper. The paper may have a basis weight of at least about 50 grams per square meter, at least about 60 grams per square meter, at least about 70 grams per square meter, or at least about 90 grams per square meter.

Where the tubular element comprises paper, the paper may have a thickness of at least about 50 micrometres. For example, the paper may have a thickness of at least about 70 micrometres, at least about 90 micrometres, or at least about 100 micrometres.

The hollow tubular element may comprise a polymer. For example, the hollow tubular element may comprise a polymeric film. The polymeric film may comprise a cellulosic film. The hollow tubular element may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibres.

Preferably, the hollow tubular element is adapted to generate a RTD between approximately 0 millimetres H2O (about 0 Pa) to approximately 20 millimetres H2O (about 100 Pa), more preferably between approximately 0 millimetres H2O (about 0 Pa) to approximately 10 millimetres H2O (about 100 Pa). The hollow tubular element therefore preferably does not contribute to the overall RTD of the aerosol-generating article

The hollow section may extend from the downstream end of the downstream section to the upstream end of the mouthpiece section. In other words, only part of the length of the downstream section may be accounted for by the hollow section, with the rest being accounted for by the mouthpiece section. That is to say, the length of the downstream section L1 is greater than the length of the hollow section L2 according to the definition above.

The one or more hollow tubes may extend from the downstream end of the downstream section to the upstream end of the mouthpiece section. In other words, the entire length of the hollow section may be accounted for by the lengths of the one or more hollow tube elements.

The hollow section may be an intermediate hollow section. Preferably, when the hollow section is an intermediate hollow section, the total length of the hollow section is no more than about 18 millimetres, more preferably no more than about 17 millimetres, more preferably no more than 16 millimetres.

According to one embodiment of the present invention, the hollow section may comprise a first hollow tubular element, or a support element, located immediately downstream of the aerosol-generating element and preferably abutting the aerosol-generating element. A mouthpiece section is optionally located downstream of the support element. The hollow section may further comprise a second hollow tubular element, or an aerosol-cooling element, located immediately downstream of the support element and preferably abutting the support element. A mouthpiece section is optionally located immediately downstream of the aerosol-cooling element. The mouthpiece section comprises one or more mouthpiece filter segments. Preferably, the mouthpiece section comprises a single mouthpiece filter segment. By way of example, the upstream end of the mouthpiece filter segment may abut the downstream end of the aerosolcooling element.

The support element may be formed from any suitable material or combination of materials. For example, the support element may be formed from one or more materials selected from the group consisting of: cellulose acetate; cardboard; crimped paper, such as crimped heat resistant paper or crimped parchment paper; and polymeric materials, such as low density polyethylene (LDPE). In a preferred embodiment, the support element is formed from cellulose acetate. Other suitable materials include polyhydroxyalkanoate (PHA) fibres.

The support element may comprise a hollow tubular element. In a preferred embodiment, the support element comprises a hollow cellulose acetate tube.

The support element is arranged substantially in alignment with the rod-shaped aerosolgenerating element. This means that the length dimension of the support element is arranged to be approximately parallel to the longitudinal direction of the rod and of the article, for example within plus or minus 10 degrees of parallel to the longitudinal direction of the rod. In preferred embodiments, the support element extends along the longitudinal axis of the rod.

The support element preferably has an outer diameter that is approximately equal to the outer diameter of the rod-shaped aerosol-generating element and to the outer diameter of the aerosol-generating article.

The support element may have an outer diameter of between 5 millimetres and 12 millimetres, for example of between 5 millimetres and 10 millimetres or of between 6 millimetres and 8 millimetres. In a preferred embodiment, the support element has an external diameter of 7.2 millimetres plus or minus 10 percent.

A peripheral wall of the support element may have a thickness of at least 1 millimetre, preferably at least about 1 .5 millimetres, more preferably at least about 2 millimetres. The support element may have a length of between about 5 millimetres and about 15 millimetres.

Preferably, the support element has a length of at least about 6 millimetres, more preferably at least about 7 millimetres.

In preferred embodiments, the support element has a length of less than about 12 millimetres, more preferably less than about 10 millimetres.

In some embodiments, the support element has a length from about 5 millimetres to about 15 millimetres, preferably from about 6 millimetres to about 15 millimetres, more preferably from about 7 millimetres to about 15 millimetres. In other embodiments, the support element has a length from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In further embodiments, the support element has a length from about 5 millimetres to about 10 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres.

In a preferred embodiment, the support element has a length of about 8 millimetres.

A ratio between the length of the support element and the length of the hollow section may be about 0.18 to about 1 .00.

Preferably a ratio between the length of the support element and the length of the hollow section is at least about 0.20, more preferably at least about 0.30, even more preferably at least about 0.40. In preferred embodiments, a ratio between the length of the support element and the length of the hollow section is less than about 0.90, more preferably less than about 0.80, even more preferably less than about 0.70.

In some embodiments, a ratio between the length of the support element and the length of the hollow section is from about 0.20 to about 0.90, preferably from about 0.30 to about 0.90, more preferably from about 0.40 to about 0.90. In other embodiments, a ratio between the length of the support element and the length of the hollow section is from about 0.2 to about 0.8, preferably from about 0.30 to about 0.80, more preferably 0.40 to about 0.80. In further embodiments, a ratio between the length of the support element and the length of the hollow section is from about 0.20 to about 0.70, preferably from about 0.30 to about 0.70, more preferably 0.40 to about 0.70.

In a particularly preferred embodiment, a ratio between the length of the support element and the length of the hollow section is about 0.50. In another particularly preferred embodiment, a ratio between the length of the support element and the length of the hollow section is about 0.29.

A ratio between the length of the support element and the length of the downstream section may be from about 0.18 to about 1.00. Preferably a ratio between the length of the support element and the length of the downstream section is at least about 0.20, more preferably at least about 0.23, even more preferably at least about 0.25. In preferred embodiments, a ratio between the length of the support element and the length of the downstream section is less than about 0.90, more preferably less than about 0.60, even more preferably less than about 0.40.

In some embodiments, a ratio between the length of the support element and the length of the downstream section is from about 0.20 to about 1.00, preferably from about 0.23 to about 1.00, more preferably from about 0.25 to about 1.00. In some embodiments, a ratio between the length of the support element and the length of the downstream section is from about 0.20 to about 0.90, preferably from about 0.23 to about 0.90, more preferably from about 0.25 to about 0.90. In other embodiments, a ratio between the length of the support element and the length of the downstream section is from about 0.20 to about 0.60, preferably from about 0.23 to about 0.60, more preferably 0.25 to about 0.60. In further embodiments, a ratio between the length of the support element and the length of the downstream section is from about 0.20 to about 0.40, preferably from about 0.23 to about 0.40, more preferably 0.25 to about 0.40.

In a particularly preferred embodiment, a ratio between the length of the support element and the length of the downstream section is about 0.29.

Preferably, a ratio between the length of the support element and the length of the rodshaped aerosol-generating element is at least about 0.30, more preferably at least about 0.40, even more preferably at least about 0.50. In preferred embodiments, a ratio between the length of the support element and the length of the rod of aerosol-generating substrate is less than about 0.90, more preferably less than about 0.80, even more preferably less than about 0.70.

In some embodiments, a ratio between the length of the support element and the length of the rod-shaped aerosol-generating element is from about 0.30 to about 0.90, preferably from about 0.40 to about 0.90, more preferably from about 0.50 to about 0.90. In other embodiments, a ratio between the length of the support element and the length of the rod of aerosol-generating substrate is from about 0.30 to about 0.80, preferably from about 0.40 to about 0.80, more preferably from about 0.50 to about 0.80. In further embodiments, a ratio between the length of the support element and the length of the rod of aerosol-generating substrate is from about 0.30 to about 0.70, preferably from about 0.40 to about 0.70, more preferably from about 0.50 to about 0.70.

In a particularly preferred embodiment, a ratio between the length of the support element and the length of the rod-shaped aerosol-generating element is about 0.67.

A ratio between the length of the support element and the overall length of the aerosolgenerating article may be from about 0.125 to about 0.375. Preferably, a ratio between the length of the support element and the overall length of the aerosol-generating article is at least about 0.13, more preferably at least about 0.14, even more preferably at least about 0.15. A ratio between the length of the support element and the overall length of the aerosol-generating article is preferably less than about 0.30, more preferably less than about 0.25, even more preferably less than about 0.20.

In some embodiments, a ratio between the length of the support element and the overall length of the aerosol-generating article is preferably from about 0.13 to about 0.30, more preferably from about 0.14 to about 0.3, even more preferably from about 0.15 to about 0.30. In other embodiments, a ratio between the length of the support element and the overall length of the aerosol-generating article is preferably from about 0.13 to about 0.25, more preferably from about 0.14 to about 0.25, even more preferably from about 0.15 to about 0.25. In further embodiments, a ratio between the length of the support element and the overall length of the aerosol-generating article is preferably from about 0.13 to about 0.20, more preferably from about 0.14 to about 0.20, even more preferably from about 0.15 to about 0.20.

In a particularly preferred embodiment, a ratio between the length of the support element and the overall length of the aerosol-generating article is about 0.18.

Preferably, in aerosol-generating articles in accordance with the present invention the support element has an average radial hardness of at least about 80 percent, more preferably at least about 85 percent, even more preferably at least about 90 percent. The support element is therefore able to provide a desirable level of hardness to the aerosol-generating article.

If desired, the radial hardness of the support element of aerosol-generating articles in accordance with the invention may be further increased by circumscribing the support element by a stiff plug wrap, for example, a plug wrap having a basis weight of at least about 80 grams per square metre (gsm), or at least about 100 gsm, or at least about 110 gsm.

During insertion of an aerosol-generating article in accordance with the invention into an aerosol-generating device for heating the aerosol-generating substrate, a user may be required to apply some force in order to overcome the resistance of the aerosol-generating substrate of the aerosol-generating article to insertion. This may damage one or both of the aerosolgenerating article and the aerosol-generating device. In addition, the application of force during insertion of the aerosol-generating article into the aerosol-generating device may displace the aerosol-generating substrate within the aerosol-generating article. This may result in the heating element of the aerosol-generating device not being properly aligned with the susceptor element provided within the aerosol-generating substrate, which may lead to uneven and inefficient heating of the aerosol-generating substrate of the aerosol-generating article. The support element is advantageously configured to resist downstream movement of the aerosol-generating substrate during insertion of the article into the aerosol-generating device. Preferably, the hollow tubular element of the support element is adapted to generate a RTD between approximately 0 millimetres H2O (about 0 Pa) to approximately 20 millimetres H2O (about 100 Pa), more preferably between approximately 0 millimetres H2O (about 0 Pa) to approximately 10 millimetres H2O (about 100 Pa). The support element therefore preferably does not contribute to the overall RTD of the aerosol-generating article.

As described above, the hollow section may further comprise a second hollow tubular element, or an aerosol-cooling element, located downstream of the aerosol-generating element. The second hollow tubular element, or aerosol-cooling element, may be located immediately downstream of the first hollow tubular element, or support element, and abut the first hollow tubular element. The first and second hollow tubular elements may define the longitudinal cavity providing the unrestricted flow channel.

The aerosol-cooling element is arranged substantially in alignment with the rod-shaped aerosol-generating element. This means that the length dimension of the aerosol-cooling element is arranged to be approximately parallel to the longitudinal direction of the rod-shaped aerosolgenerating element and of the article, for example within plus or minus 10 degrees of parallel to the longitudinal direction of the rod-shaped element. In preferred embodiments, the aerosolcooling element extends along the longitudinal axis of the rod-shaped aerosol-generating element.

In aerosol-generating articles in accordance with the present invention the aerosol-cooling element is in the form of a hollow tubular element that defines a cavity extending all the way from an upstream end of the aerosol-cooling element to a downstream end of the aerosol-cooling element. Preferably, a ventilation zone is provided at a location along the hollow tubular element.

The inventors have found that a satisfactory cooling of the stream of aerosol generated upon heating the aerosol-generating substrate and drawn through one such aerosol-cooling element is achieved by providing a ventilation zone at a location along the hollow tubular element. Further, the inventors have found that, as will be described in more detail below, by arranging the ventilation zone at a precisely defined location along the length of the aerosol-cooling element and by preferably utilising a hollow tubular element having a predetermined peripheral wall thickness or internal volume, it may be possible to counter the effects of the increased aerosol dilution caused by the admission of ventilation air into the article.

Without wishing to be bound by theory, it is hypothesised that, because the temperature of the aerosol stream is rapidly lowered by the introduction of ventilation air as the aerosol is travelling towards the mouthpiece, the ventilation air being admitted into the aerosol stream at a location relatively close to the upstream end of the aerosol-cooling element (that is, sufficiently close to the susceptor element extending within the rod-shaped aerosol-generating element, which is the heat source during use), a dramatic cooling of the aerosol stream is achieved, which has a favourable impact on the condensation and nucleation of the aerosol particles. Accordingly, the overall proportion of the aerosol particulate phase to the aerosol gas phase may be enhanced compared with existing, non-ventilated aerosol-generating articles.

At the same time, keeping the thickness of the peripheral wall of the hollow tubular element relatively low ensures that the overall internal volume of the hollow tubular element - which is made available for the aerosol to begin the nucleation process as soon as the aerosol components leave the rod-shaped aerosol-generating element - and the cross-sectional surface area of the hollow tubular element are effectively maximised, whilst at the same time ensuring that the hollow tubular element has the necessary structural strength to prevent a collapse of the aerosol-generating article as well as to provide some support to the rod-shaped aerosolgenerating element, and that the RTD of the hollow tubular element is minimised. Greater values of cross-sectional surface area of the cavity of the hollow tubular element are understood to be associated with a reduced speed of the aerosol stream travelling along the aerosol-generating article, which is also expected to favour aerosol nucleation. Further, it would appear that by utilising a hollow tubular element having a relatively low thickness, it is possible to substantially prevent diffusion of the ventilation air prior to its contacting and mixing with the stream of aerosol, which is also understood to further favour nucleation phenomena. In practice, by providing a more controllably localised cooling of the stream of volatilised species, it is possible to enhance the effect of cooling on the formation of new aerosol particles.

The aerosol-cooling element preferably has an outer diameter that is approximately equal to the outer diameter of the rod-shaped aerosol-generating element and to the outer diameter of the aerosol-generating article.

The aerosol-cooling element may have an outer diameter of between 5 millimetres and 12 millimetres, for example of between 5 millimetres and 10 millimetres or of between 6 millimetres and 8 millimetres. In a preferred embodiment, the aerosol-cooling element has an external diameter of 7.2 millimetres plus or minus 10 percent.

Preferably, the hollow tubular element of the aerosol-cooling element has an internal diameter of at least about 2 millimetres. More preferably, the hollow tubular element of the aerosol-cooling element has an internal diameter of at least about 2.5 millimetres. Even more preferably, the hollow tubular element of the aerosol-cooling element has an internal diameter of at least about 3 millimetres.

A peripheral wall of the aerosol-cooling element may have a thickness of less than about 2.5 millimetres, preferably less than about 1.5 millimetres, more preferably less than about 1250 micrometres, even more preferably less than about 1000 micrometres. In particularly preferred embodiments, the peripheral wall of the aerosol-cooling element has a thickness of less than about 900 micrometres, preferably less than about 800 micrometres. In an embodiment, a peripheral wall of the aerosol-cooling element has a thickness of about 2 millimetres.

The aerosol-cooling element may have a length of between 5 millimetres and 15 millimetres.

Preferably, the aerosol-cooling element has a length of at least about 6 millimetres, more preferably at least about 7 millimetres.

In preferred embodiments, the aerosol-cooling element has a length of less than about 12 millimetres, more preferably less than about 10 millimetres.

In some embodiments, the aerosol-cooling element has a length from about 5 millimetres to about 15 millimetres, preferably from about 6 millimetres to about 15 millimetres, more preferably from about 7 millimetres to about 15 millimetres. In other embodiments, the aerosolcooling element has a length from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In further embodiments, the aerosol-cooling element has a length from about 5 millimetres to about 10 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres.

In particularly preferred embodiments of the invention, the aerosol-cooling element has a length of less than 10 millimetres. For example, in one particularly preferred embodiment, the aerosol-cooling element has a length of 8 millimetres. In such embodiments, the aerosol-cooling element therefore has a relatively short length compared to the aerosol-cooling elements of prior art aerosol-generating articles. A reduction in the length of the aerosol-cooling element is possible due to the optimised effectiveness of the hollow tubular element forming the aerosol-cooling element in the cooling and nucleation of the aerosol. The reduction of the length of the aerosolcooling element advantageously reduces the risk of deformation of the aerosol-generating article due to compression during use, since the aerosol-cooling element typically has a lower resistance to deformation than the mouthpiece. Furthermore, the reduction of the length of the aerosolcooling element may provide a cost benefit to the manufacturer since the cost of a hollow tubular element is typically higher per unit length than the cost of other elements such as a mouthpiece.

A ratio between the length of the aerosol-cooling element and the length of the hollow section may be about 0.18 to about 1.00.

Preferably a ratio between the length of the aerosol-cooling element and the length of the hollow section is at least about 0.20, more preferably at least about 0.30, even more preferably at least about 0.40. In preferred embodiments, a ratio between the length of the aerosol-cooling element and the length of the hollow section is less than about 0.90, more preferably less than about 0.80, even more preferably less than about 0.70. In some embodiments, a ratio between the length of the aerosol-cooling element and the length of the hollow section is from about 0.20 to about 0.90, preferably from about 0.30 to about 0.90, more preferably from about 0.40 to about 0.90. In other embodiments, a ratio between the length of the aerosol-cooling element and the length of the hollow section is from about 0.20 to about 0.80, preferably from about 0.30 to about 0.80, more preferably 0.40 to about 0.80. In further embodiments, a ratio between the length of the aerosol-cooling element and the length of the hollow section is from about 0.20 to about 0.70, preferably from about 0.30 to about 0.70, more preferably 0.40 to about 0.70.

In a particularly preferred embodiment, a ratio between the length of the aerosol-cooling element and the length of the hollow section is about 0.29. In another particularly preferred embodiment, a ratio between the length of the aerosol-cooling element and the length of the hollow section is about 0.50.

A ratio between the length of the aerosol-cooling element and the length of the downstream section may be about 0.18 to about 1.00.

Preferably a ratio between the length of the aerosol-cooling element and the length of the downstream section is at least about 0.20, more preferably at least about 0.23, even more preferably at least about 0.25. In preferred embodiments, a ratio between the length of the aerosol-cooling element and the length of the downstream section is less than about 0.90, more preferably less than about 0.60, even more preferably less than about 0.50.

In some embodiments, a ratio between the length of the aerosol-cooling element and the length of the downstream section is from about 0.20 to about 0.90, preferably from about 0.23 to about 0.90, more preferably from about 0.25 to about 0.90. In other embodiments, a ratio between the length of the aerosol-cooling element and the length of the downstream section is from about 0.20 to about 0.60, preferably from about 0.23 to about 0.60, more preferably 0.25 to about 0.60. In further embodiments, a ratio between the length of the aerosol-cooling element and the length of the downstream section is from about 0.20 to about 0.50, preferably from about 0.23 to about 0.40, more preferably 0.25 to about 0.50.

In a particularly preferred embodiment, a ratio between the length of the aerosol-cooling element and the length of the downstream section is about 0.29.

A ratio between the length of the aerosol-cooling element and the length of the rod-shaped aerosol-generating element may be from about 0.25 to about 1.00.

Preferably, a ratio between the length of the aerosol-cooling element and the length of the rod-shaped aerosol-generating element is at least about 0.30, more preferably at least about 0.40, even more preferably at least about 0.50. In preferred embodiments, a ratio between the length of the aerosol-cooling element and the length of the rod-shaped aerosol-generating element is less than about 0.90, more preferably less than about 0.80, even more preferably less than about

0.70.

In some embodiments, a ratio between the length of the aerosol-cooling element and the length of the rod-shaped aerosol-generating element is from about 0.30 to about 0.90, preferably from about 0.40 to about 0.90, more preferably from about 0.50 to about 0.90. In other embodiments, a ratio between the length of the aerosol-cooling element and the length of the rodshaped aerosol-generating element is from about 0.30 to about 0.80, preferably from about 0.40 to about 0.80, more preferably from about 0.50 to about 0.80. In further embodiments, a ratio between the length of the aerosol-cooling element and the length of the rod-shaped aerosolgenerating element is from about 0.30 to about 0.70, preferably from about 0.40 to about 0.70, more preferably from about 0.50 to about 0.70.

In a particularly preferred embodiment, a ratio between the length of the aerosol-cooling element and the length of the rod-shaped aerosol-generating element is about 0.67.

A ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article substrate may be from about 0.125 to about 0.375.

Preferably, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is at least about 0.13, more preferably at least about 0.14, even more preferably at least about 0.15. A ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is preferably less than about 0.30, more preferably less than about 0.25, even more preferably less than about 0.20.

In some embodiments, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is preferably from about 0.13 to about 0.30, more preferably from about 0.14 to about 0.30, even more preferably from about 0.15 to about 0.30. In other embodiments, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is preferably from about 0.13 to about 0.25, more preferably from about 0.14 to about 0.25, even more preferably from about 0.15 to about 0.25. In further embodiments, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is preferably from about 0.13 to about 0.20, more preferably from about 0.14 to about 0.20, even more preferably from about 0.15 to about 0.20.

In a particularly preferred embodiment, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is about 0.18.

Preferably, the length of the mouthpiece section is at least 1 millimetre greater than the length of the aerosol-cooling element, more preferably at least 2 millimetres greater than the length of the aerosol-cooling element, more preferably at least 3 millimetres greater than the length of the aerosol-cooling element. A reduction in the length of the aerosol-cooling element, as described above, can advantageously allow for an increase in the length of other elements of the aerosol-generating article, such as the mouthpiece section. The potential technical benefits of providing a relatively long mouthpiece section are described below.

In some preferred embodiments, the mouthpiece section comprises a single mouthpiece filter segment. Preferably, the length of the mouthpiece filter segment is at least 1 millimetre greater than the length of the aerosol-cooling element, more preferably at least 2 millimetres greater than the length of the aerosol-cooling element, more preferably at least 3 millimetres greater than the length of the aerosol-cooling element.

In some embodiments, a second aerosol-cooling element may be located downstream of the aerosol-cooling element. The second aerosol-cooling element may be in the form of a third hollow tubular element. The second aerosol-cooling element may abut the aerosol-cooling element at the downstream end of the aerosol-cooling element. The third hollow tubular element may abut the second hollow tubular element at the downstream end of the second hollow tubular element . In such embodiments, the hollow section comprises a first, second and third hollow tubular element, the first, second and third hollow tubular elements defining the longitudinal cavity providing the unrestricted flow channel. The second aerosol-cooling element may extend to the mouth end of the aerosol-generating article. The third hollow tubular element may extend to the mouth end of the aerosol-generating article. The support element, aerosol-cooling element and second aerosol-cooling element may form a hollow section extending from the downstream end of the rod of aerosol-generating substrate to the mouth end of the aerosol-generating article. The first, second and third hollow tubular elements may form a hollow section extending from the downstream end of the rod of aerosol-generating substrate to the mouth end of the aerosolgenerating article.

Preferably, the second aerosol cooling element has a length of between 5 millimetres and 15 millimetres. In a particularly preferred embodiment, the length of the second aerosol-cooling element may be 12 millimetres.

Preferably, the third hollow tubular element comprising the second aerosol-cooling element has an internal diameter of at least about 2 millimetres. More preferably, the hollow tubular element of the second aerosol-cooling element has an internal diameter of at least about 2.5 millimetres. Even more preferably, the hollow tubular element of the second aerosol-cooling element has an internal diameter of at least about 3 millimetres.

A peripheral wall of the second aerosol-cooling element may have a thickness of less than about 2.5 millimetres, preferably less than about 1.5 millimetres, more preferably less than about 1250 micrometres, even more preferably less than about 1000 micrometres. In particularly preferred embodiments, the peripheral wall of the second aerosol-cooling element has a thickness of less than about 900 micrometres, preferably less than about 800 micrometres. In an embodiment, a peripheral wall of the second aerosol-cooling element has a thickness of about 2 millimetres.

Preferably, in aerosol-generating articles in accordance with the present invention the aerosol-cooling element has an average radial hardness of at least about 80 percent, more preferably at least about 85 percent, even more preferably at least about 90 percent. The aerosolcooling element is therefore able to provide a desirable level of hardness to the aerosolgenerating article.

If desired, the radial hardness of the aerosol-cooling element of aerosol-generating articles in accordance with the invention may be further increased by circumscribing the aerosolcooling element by a stiff plug wrap, for example, a plug wrap having a basis weight of at least about 80 grams per square metre (gsm), or at least about 100 gsm, or at least about 110 gsm.

As used herein, the term “radial hardness” refers to resistance to compression in a direction transverse to a longitudinal axis of an element. Radial hardness of an aerosolgenerating article around a given element may be determined by applying a load across the article at the location of the element, transverse to the longitudinal axis of the article, and measuring the average (mean) depressed diameters of the articles. Radial hardness is given by: 100 %

where Ds is the original (undepressed) diameter, and Dd is the depressed diameter after applying a set load for a set duration. The harder the material, the closer the hardness is to 100 percent.

To determine the hardness of a portion (such as a support element or aerosol-cooling element provided in the form of a hollow tube element) of an aerosol article, aerosol-generating articles should be aligned parallel in a plane and the same portion of each aerosol-generating article to be tested should be subjected to a set load for a set duration. This test is performed using a known DD60A Densimeter device (manufactured and made commercially available by Heinr Borgwaldt GmbH, Germany), which is fitted with a measuring head for aerosol-generating articles, such as cigarettes, and with an aerosol-generating article receptacle.

The load is applied using two load-applying cylindrical rods, which extend across the diameter of all of the aerosol-generating articles at once. According to the standard test method for this instrument, the test should be performed such that twenty contact points occur between the aerosol-generating articles and the load applying cylindrical rods. In some cases, the hollow tube elements to be tested may be long enough such that only ten aerosol-generating articles are needed to form twenty contact points, with each smoking article contacting both load applying rods (because they are long enough to extend between the rods). In other cases, if the support elements are too short to achieve this, then twenty aerosol-generating articles should be used to form the twenty contact points, with each aerosol-generating article contacting only one of the load applying rods, as further discussed below.

Two further stationary cylindrical rods are located underneath the aerosol-generating articles, to support the aerosol-generating articles and counteract the load applied by each of the load applying cylindrical rods.

For the standard operating procedure for such an apparatus, an overall load of 2 kg is applied for a duration of 20 seconds. After 20 seconds have elapsed (and with the load still being applied to the smoking articles), the depression in the load applying cylindrical rods is determined, and then used to calculate the hardness from the above equation. The temperature is kept in the region of 22 degrees Celsius ± 2 degrees. The test described above is referred to as the DD60A Test. The standard way to measure the filter hardness is when the aerosol-generating article have not been consumed. Additional information regarding measurement of average radial hardness can be found in, for example, U.S. Published Patent Application Publication Number 2016/0128378.

The aerosol-cooling element may be formed from any suitable material or combination of materials. For example, the aerosol-cooling element may be formed from one or more materials selected from the group consisting of: cellulose acetate; cardboard; crimped paper, such as crimped heat resistant paper or crimped parchment paper; and polymeric materials, such as low density polyethylene (LDPE). Other suitable materials include polyhydroxyalkanoate (PHA) fibres.

In a preferred embodiment, the aerosol-cooling element is formed from cellulose acetate.

Preferably, the hollow tubular element of the aerosol-cooling element is adapted to generate a RTD between approximately 0 millimetres H2O (about 0 Pa) to approximately 20 millimetres H2O (about 100 Pa), more preferably between approximately 0 millimetres H2O (about 0 Pa) to approximately 10 millimetres H2O (about 100 Pa).

In aerosol-generating articles in accordance with the present invention the overall RTD of the article depends essentially on the RTD of the rod and optionally on the RTD of the mouthpiece and/or upstream plug. This is because the hollow tubular element of the aerosol-cooling element and the hollow tubular element of the support element are substantially empty and, as such, substantially only marginally contribute to the overall RTD of the aerosol-generating article.

In some embodiments wherein the hollow section comprises both a support element comprising a first hollow tube element and an aerosol-cooling element comprising a second hollow tubular element, the internal diameter (DSTS) of the second hollow tubular element is preferably greater than the internal diameter (DFTS) of the first hollow tubular element. In more detail, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is preferably at least about 1.25. More preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is preferably at least about 1.30. Even more preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is preferably at least about 1.40. In particularly preferred embodiments, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is at least about 1.50, more preferably at least about 1.60.

A ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is preferably less than or equal to about 2.50. More preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is preferably less than or equal to about 2.25. Even more preferably, ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is preferably less than or equal to about 2.00.

In some embodiments, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.25 to about 2.50. Preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.30 to about 2.50. More preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.40 to about 2.50. In particularly preferred embodiments, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.50 to about 2.50.

In other embodiments, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.25 to about 2.25. Preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.30 to about 2.25. More preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.40 to about 2.25. In particularly preferred embodiments, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.50 to about 2.25.

In further embodiments, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1 .25 to about 2.00. Preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1 .30 to about 2.00. More preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.40 to about 2.00. In particularly preferred embodiments, a ratio between the internal diameter (DSTS) of the second hollow tubular element and the internal diameter (DFTS) of the first hollow tubular element is from about 1.50 to about 2.00.

In those embodiments wherein the article further comprises an elongate susceptor element arranged longitudinally within the aerosol-generating substrate, as described below, a ratio between the internal diameter (DFTS) of the first hollow tubular element and a width of the susceptor element is preferably at least about 0.20. More preferably, a ratio between the internal diameter (DFTS) of the first hollow tubular element and a width of the susceptor element is at least about 0.30. Even more preferably, a ratio between the internal diameter (DFTS) of the first hollow tubular element and a width of the susceptor element is at least about 0.40.

In addition, or as an alternative, a ratio between the internal diameter (DSTS) of the second hollow tubular element and a width of the susceptor element is preferably at least about 0.20. More preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and a width of the susceptor element is at least about 0.50. Even more preferably, a ratio between the internal diameter (DSTS) of the second hollow tubular element and a width of the susceptor element is at least about 0.80.

Preferably, a ratio between a volume of the cavity of the first hollow tubular element and a volume of the cavity of the second hollow tubular element is at least about 0.10. More preferably, a ratio between a volume of the cavity of the first hollow tubular element and a volume of the cavity of second hollow tubular element is at least about 0.20. Even more preferably, a ratio between a volume of the cavity of first hollow tubular element and a volume of the cavity of second hollow tubular element is at least about 0.30.

A ratio between a volume of the cavity of the first hollow tubular element and a volume of the cavity of the second hollow tubular element is preferably less than or equal to about 0.90. More preferably, a ratio between a volume of the cavity of the first hollow tubular element and a volume of the cavity of the second hollow tubular element is preferably less than or equal to about 0.70. Even more preferably, a ratio between a volume of the cavity of the first hollow tubular element and a volume of the cavity of the second hollow tubular element is preferably less than or equal to about 0.50.

In aerosol-generating articles according to the invention, the downstream section may include ventilation. The ventilation may be provided to allow cooler air from outside the aerosolgenerating article to enter the interior of the downstream section. The term “ventilation level” is used throughout the present specification to denote a volume ratio between the airflow admitted into the aerosol-generating article via the ventilation zone (ventilation airflow) and the sum of aerosol airflow and the ventilation airflow. The greater the ventilation level, the higher the dilution of the aerosol flow delivered to the consumer.

The aerosol-generating article may typically have a ventilation level of at least about 10 percent, preferably at least about 20 percent.

In preferred embodiments, the aerosol-generating article has a ventilation level of at least about 20 percent or 25 percent or 30 percent. More preferably, the aerosol-generating article has a ventilation level of at least about 35 percent.

The aerosol-generating article preferably has a ventilation level of less than about 80 percent. More preferably, the aerosol-generating article has a ventilation level of less than about 60 percent or less than about 50 percent.

The aerosol-generating article may typically have a ventilation level of between about 10 percent and about 80 percent.

In some embodiments, the aerosol-generating article has a ventilation level from about 20 percent to about 80 percent, preferably from about 20 percent to about 60 percent, more preferably from about 20 percent to about 50 percent. In other embodiments, the aerosolgenerating article has a ventilation level from about 25 percent to about 80 percent, preferably from about 25 percent to about 60 percent, more preferably from about 25 percent to about 50 percent. In further embodiments, the aerosol-generating article has a ventilation level from about 30 percent to about 80 percent, preferably from about 30 percent to about 60 percent, more preferably from about 30 percent to about 50 percent.

In some particularly preferred embodiments, the aerosol-generating article has a ventilation level of about 30 percent. In some particularly preferred embodiments, the aerosolgenerating article has a ventilation level of about 45 percent.

Without wishing to be bound by theory, the inventors have found that the temperature drop caused by the admission of cooler, external air into the hollow tubular element via the ventilation zone may have an advantageous effect on the nucleation and growth of aerosol particles.

Formation of an aerosol from a gaseous mixture containing various chemical species depends on a delicate interplay between nucleation, evaporation, and condensation, as well as coalescence, all the while accounting for variations in vapour concentration, temperature, and velocity fields. The so-called classical nucleation theory is based on the assumption that a fraction of the molecules in the gas phase are large enough to stay coherent for long times with sufficient probability (for example, a probability of one half). These molecules represent some kind of a critical, threshold molecule clusters among transient molecular aggregates, meaning that, on average, smaller molecule clusters are likely to disintegrate rather quickly into the gas phase, while larger clusters are, on average, likely to grow. Such critical cluster is identified as the key nucleation core from which droplets are expected to grow due to condensation of molecules from the vapour. It is assumed that virgin droplets that just nucleated emerge with a certain original diameter, and then may grow by several orders of magnitude. This is facilitated and may be enhanced by rapid cooling of the surrounding vapour, which induces condensation. In this connection, it helps to bear in mind that evaporation and condensation are two sides of one same mechanism, namely gas-liquid mass transfer. While evaporation relates to net mass transfer from the liquid droplets to the gas phase, condensation is net mass transfer from the gas phase to the droplet phase. Evaporation (or condensation) will make the droplets shrink (or grow), but it will not change the number of droplets.

In this scenario, which may be further complicated by coalescence phenomena, the temperature and rate of cooling can play a critical role in determining how the system responds. In general, different cooling rates may lead to significantly different temporal behaviours as concerns the formation of the liquid phase (droplets), because the nucleation process is typically nonlinear. Without wishing to be bound by theory, it is hypothesised that cooling can cause a rapid increase in the number concentration of droplets, which is followed by a strong, short-lived increase in this growth (nucleation burst). This nucleation burst would appear to be more significant at lower temperatures. Further, it would appear that higher cooling rates may favour an earlier onset of nucleation. By contrast, a reduction of the cooling rate would appear to have a favourable effect on the final size that the aerosol droplets ultimately reach.

Therefore, the rapid cooling induced by the admission of external air into the hollow tubular element via the ventilation zone can be favourably used to favour nucleation and growth of aerosol droplets. However, at the same time, the admission of external air into the hollow tubular element has the immediate drawback of diluting the aerosol stream delivered to the consumer.

The inventors have surprisingly found how the favourable effect of enhanced nucleation promoted by the rapid cooling induced by the introduction of ventilation air into the article is capable of significantly countering the less desirable effects of dilution. As such, satisfactory values of aerosol delivery are consistently achieved with aerosol-generating articles in accordance with the invention.

The inventors have also surprisingly found that the diluting effect on the aerosol - which can be assessed by measuring, in particular, the effect on the delivery of aerosol former (such as glycerol) included in the aerosol-generating substrate) is advantageously minimised when the ventilation level is within the ranges described above. In particular, ventilation levels between 30 percent and 50 percent have been found to lead to particularly satisfactory values of glycerine delivery. At the same time, the extent of nucleation and, as a consequence, the delivery of nicotine and aerosol-former (for example, glycerol) are enhanced. This is particularly advantageous with “short” aerosol-generating articles, such as ones wherein a length of the rod of aerosol-generating substrate is less than about 40 millimetres, preferably less than 25 millimetres, even more preferably less than 20 millimetres, or wherein an overall length of the aerosol-generating article is less than about 70 millimetres, preferably less than about 60 millimetres, even more preferably less than 50 millimetres. As will be appreciated, in such aerosol-generating articles, there is little time and space for the aerosol to form and for the particulate phase of the aerosol to become available for delivery to the consumer.

Further, because the ventilated hollow tubular element substantially does not contribute to the overall RTD of the aerosol-generating article, in aerosol-generating articles in accordance with the invention the overall RTD of the article can advantageously be fine-tuned by adjusting the length and density of the rod of aerosol-generating substrate or the length and optionally the length and density of a segment of filtration material forming part of the mouthpiece or the length and density of a segment of filtration material provided upstream of the aerosol-generating substrate and the susceptor element. Thus, aerosol-generating articles that have a predetermined RTD can be manufactured consistently and with great precision, such that satisfactory levels of RTD can be provided for the consumer even in the presence of ventilation.

The ventilation into the downstream section may be provided along substantially the entire length of the downstream section. Where this is the case, the downstream section may comprise a porous material which allows air to enter the downstream section. For example, where the downstream section comprises a hollow tubular element, the hollow element may be formed from a porous material which allows air to enter the interior of the hollow tubular element. Where the downstream section comprises a wrapper, the wrapper may be formed from a porous material which allows air to enter the interior of the hollow tubular element.

The downstream section may comprise a first ventilation zone for providing ventilation into the downstream section. The ventilation zone comprises a portion of the downstream section through which a greater volume of air may pass compared to the remainder of the downstream section. For example, the ventilation zone may be a portion of the downstream section having a higher porosity than the remainder of the downstream section.

The ventilation zone may comprise a plurality of perforations through the peripheral wall of the hollow tubular element. In some embodiments, the ventilation zone comprises a plurality of perforations through the peripheral wall of the aerosol-cooling element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. In some embodiments, the ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed online during manufacturing of the aerosol-generating article. Preferably, each circumferential row of perforations comprises from 8 to 30 perforations. Where the aerosol-generating article comprises a combining plug wrap the ventilation zone preferably comprises at least one corresponding circumferential row of perforation holes provided through a portion of the combining plug wrap. These may also be formed online during manufacture of the smoking article. Preferably, the circumferential row or rows of perforation holes provided through a portion of the combining plug wrap are in substantial alignment with the row or rows of perforations through the downstream section.

Where the aerosol-generating article comprises a band of tipping paper, wherein the band of tipping paper extends over the circumferential row or rows of perforations in the downstream section, the ventilation zone preferably comprises at least one corresponding circumferential row of perforation holes provided through the band of tipping paper. These may also be formed online during manufacture of the smoking article. Preferably, the circumferential row or rows of perforation holes provided through the band of tipping paper are in substantial alignment with the row or rows of perforations through the downstream section.

The first line of perforation holes may comprise at least one perforation hole having a width of at least about 50 micrometres. For example, the first line of perforation holes may comprise at least one perforation hole having a width of at least about 65 micrometres, at least about 80 micrometres, at least about 90 micrometres, or at least about 100 micrometres.

The first line of perforation holes may comprise at least one perforation hole having a width no greater than about 200 micrometres. For example, the first line of perforation holes may comprise at least one perforation hole having a width no greater than about 175 micrometres, no greater than about 150 micrometres, no greater than about 125 micrometres, or no greater than about 120 micrometres.

The first line of perforation holes may comprise at least one perforation hole having a width of between about 50 micrometres and about 200 micrometres, between about 65 micrometres and about 175 micrometres, between about 90 micrometres and about 150 micrometres, or between about 100 micrometres and about 120 micrometres.

Where the perforation holes are formed from using laser perforation techniques, the width of the perforation holes may be determined by the focus diameter of the laser.

The first line of perforation holes may comprise at least one perforation hole having a length of at least about 400 micrometres. For example, the first line of perforation holes may comprise at least one perforation hole having a length of at least about 425 micrometres, at least about 450 micrometres, at least about 475 micrometres, or at least about 500 micrometres.

The first line of perforation holes may comprise at least one perforation hole having a length no greater than about 1 millimetre. For example, the first line of perforation holes may comprise at least one perforation hole having a length no greater than about 950 micrometres, no greater than about 900 micrometres, no greater than about 850 micrometres, or no greater than about 800 micrometres.

The first line of perforation holes may comprise at least one perforation hole having a length of between about 400 micrometres and about 1 millimetre, between about 425 micrometres and about 950 micrometres, between about 450 micrometres and about 900 micrometres, between about 475 micrometres and about 850 micrometres, or between about 500 micrometres and about 800 micrometres.

The first line of perforation holes may comprise at least one perforation hole having an opening area of at least about 0.01 millimetres squared. For example, the first line of perforation holes may comprise at least one perforation hole having an opening area of at least about 0.02 millimetres squared, at least about 0.03 millimetres squared, or at least about 0.05 millimetres squared.

The first line of perforation holes may comprise at least one perforation hole having an opening area of no more than about 0.5 millimetres squared. For example, the first line of perforation holes may comprise at least one perforation hole having an opening area of no more than about 0.3 millimetres squared, no more than about 0.25 millimetres squared, or no more than about 0.1 millimetres squared.

The first line of perforation holes may comprise at least one perforation hole having an opening area of between about 0.01 millimetres squared and about 0.5 millimetres squared, between about 0.02 millimetres squared and about 0.3 millimetres squared, between about 0.03 millimetres squared and about 0.25 millimetres squared, or between about 0.05 millimetres squared and about 0.1 millimetres squared. The first line of perforation holes may comprise at least one perforation hole having an opening area of between about 0.05 millimetres squared and about 0.096 millimetres squared.

As set out above, the aerosol-generating article may comprise a wrapper circumscribing at least a portion of the downstream section, the ventilation zone may comprise a porous portion of the wrapper.

The wrapper may be a paper wrapper, and the ventilation zone may comprise a portion of porous paper.

The porous portion of the wrapper forming the ventilation zone may have a basis weight which is lower than that of a portion of the wrapper which does not form part of the first ventilation zone.

The porous portion of the wrapper forming the ventilation zone may have a thickness which is lower than that of a portion of the wrapper which does not form part of the first ventilation zone. The upstream end of the ventilation zone may be less than 10 millimetres from the downstream end of the aerosol-generating substrate.

For example, the upstream end of the ventilation zone may be less than 8 millimetres, less than 5 millimetres, less than 3 millimetres, or less than 1 millimetre from the from the downstream end of the aerosol-generating substrate.

The upstream end of the ventilation zone may be longitudinally aligned with the downstream end of the aerosol-generating substrate.

The downstream end of the ventilation zone may be no further than 10 millimetres from the downstream end of the aerosol-generating substrate. In other words, the ventilation zone may be entirely located within 10 millimetres of the aerosol-generating substrate.

For example, the downstream end of the ventilation zone may be no further than 8 millimetres, no further than 5 millimetres, or no further than 3 millimetres from the downstream end of the aerosol-generating substrate.

The ventilation zone may be located anywhere along the length of the downstream section. The downstream end of the ventilation zone may be located no more than about 25 millimetres from the downstream end of the aerosol-generating article. For example, the ventilation zone may be located no more than about 20 millimetres from the downstream end of the aerosol-generating article.

Locating the ventilation zone as outlined above may advantageously prevent the ventilation zone being occluded when the aerosol-generating article is inserted into an aerosolgenerating device.

The downstream end of the ventilation zone may be located at least about 8 millimetres from the downstream end of the aerosol-generating article. For example, the downstream end of the ventilation zone may be located at least about 10 millimetres, at least 12 millimetres, or at least about 15 millimetres from the downstream end of the aerosol-generating article.

Locating the ventilation zone as outlined above may advantageously prevent the ventilation zone being occluded by a user’s mouth or lips when the aerosol-generating article is in use.

The downstream end of the ventilation zone may be located between about 8 millimetres and about 25 millimetres, between about 10 millimetres and about 25 millimetres, or between about 15 millimetres and about 20 millimetres from the downstream end of the aerosol-generating article. The downstream end of the ventilation zone may be located about 18 millimetres from the downstream end of the aerosol-generating article.

The upstream end of the ventilation zone may be located at least about 20 millimetres from the upstream end of the aerosol-generating article. For example, the upstream end of the ventilation zone may be located at least about 25 millimetres from the upstream end of the aerosol-generating article.

The upstream end of the ventilation zone may be located no more than 37 millimetres from the upstream end of the aerosol-generating article. For example, the upstream end of the ventilation zone may be located no more than about 30 millimetres from the upstream end of the aerosol-generating article.

The upstream end of the ventilation zone may be located between about 20 millimetres and about 37 millimetres, or between about 25 millimetres and about 30 millimetres from the upstream end of the aerosol-generating article. The upstream end of the ventilation zone may be located about 27 millimetres from the upstream end of the aerosol-generating article.

The ventilation zone may have any length. The ventilation zone may have a length of at least 0.5 millimetres. In other words, the longitudinal distance between the downstream end of the ventilation zone and the an upstream end of the ventilation zone is at least 0.5 millimetres. For example, the ventilation zone may have a length of at least 1 millimetre, at least 2 millimetres, at least 5 millimetres, or at least 8 millimetres.

The ventilation zone may have a length of no more than 10 millimetres. For example, the ventilation zone may have a length of no more than 8 millimetres, or no more than 5 millimetres.

The ventilation zone may have a length of between 0.5 millimetres and 10 millimetres. For example, the ventilation zone may have a length of between 1 millimetre and 8 millimetres, or between 2 millimetres and 5 millimetres.

As defined above, the downstream section of the aerosol-generating article of one embodiment of the present invention comprises a mouthpiece section. The mouthpiece section is preferably located at the downstream end or mouth end of the aerosol-generating article. The mouthpiece section comprises at least one mouthpiece filter segment formed of a fibrous filtration material for filtering the aerosol that is generated from the aerosol-generating substrate. Suitable fibrous filtration materials would be known to the skilled person. Particularly preferably, the at least one mouthpiece filter segment comprises a cellulose acetate filter segment formed of cellulose acetate tow.

In certain preferred embodiments, the mouthpiece section consists of a single mouthpiece filter segment. The single mouthpiece filter segment may extend all the way to the mouth end of the aerosol-generating article. In alternative embodiments, the mouthpiece section includes two or more mouthpiece filter segments axially aligned in an abutting end to end relationship with each other.

The upstream end of the mouthpiece section is defined by the upstream end of the most upstream mouthpiece filter segment. When a single mouthpiece filter segment is present, the upstream end of the mouthpiece section is defined by the upstream end of the mouthpiece filter segment. The downstream end of the mouthpiece section is defined by the downstream or mouth end of the aerosol-generating article.

In certain embodiments of the invention, the mouthpiece section may comprise a mouth end cavity at the downstream end of the mouthpiece section, downstream of the mouthpiece filter segment as described above. The mouth end cavity may be defined by a hollow tubular element provided at the downstream end of the mouthpiece filter segment. Alternatively, the mouth end cavity may be defined by the outer wrapper of the mouthpiece section, wherein the outer wrapper extends in a downstream direction from the mouthpiece filter segment.

The mouthpiece filter segment may optionally comprise a flavourant, which may be provided in any suitable form. For example, the mouthpiece filter segment may comprise one or more capsules, beads or granules of a flavourant, or one or more flavour loaded threads or filaments.

According to this embodiment of the present invention, the downstream section of the aerosol-generating article may comprise a first hollow tubular element, or a support element, located immediately downstream of the rod of aerosol-generating substrate. The mouthpiece section is preferably located downstream of the support element. The downstream section further comprises a second hollow tubular element, or an aerosol-cooling element, located immediately downstream of the support element. The mouthpiece section is preferably located downstream of both the support element and the aerosol-cooling element. Particularly preferably, the mouthpiece section is located immediately downstream of the aerosol-cooling element. By way of example, the mouthpiece filter segment may abut the downstream end of the aerosol-cooling element. The mouthpiece section preferably comprises a single mouthpiece filter segment extending all the way to the mouth end of the aerosol-generating article.

Preferably, the mouthpiece filter segment has a low particulate filtration efficiency.

Preferably, the mouthpiece section is circumscribed by a plug wrap. Preferably, the mouthpiece section is unventilated such that air does not enter the aerosol-generating article along the mouthpiece section.

The mouthpiece section is preferably connected to one or more of the adjacent upstream components of the aerosol-generating article by means of a tipping wrapper. Preferably, the mouthpiece section has an RTD of less than about 25 millimetres H2O. More preferably, the mouthpiece section has an RTD of less than about 20 millimetres H2O. More preferably, the mouthpiece section has an RTD of less than about 15 millimetres H2O.

Values of RTD from about 10 millimetres H2O to about 25 millimetres H2O or from about 10 millimetres H2O to about 15 millimetres H2O are particularly preferred because a mouthpiece section having one such RTD is expected to contribute minimally to the overall RTD of the aerosol-generating article substantially does not exert a filtration action on the aerosol being delivered to the consumer.

The one or more hollow tubular elements in the downstream section provide a negligible RTD, such that in this embodiment the mouthpiece section provides the major contribution to the

RTD of the downstream section. Preferably, the downstream section has an RTD of less than about 25 millimetres H2O. More preferably, the downstream section has an RTD of less than about 20 millimetres H2O. More preferably, the downstream section has an RTD of less than about 15 millimetres H2O. Values of RTD from about 10 millimetres H2O to about 25 millimetres H2O or from about 10 millimetres H2O to about to about 15 millimetres H2O are particularly preferred.

The mouthpiece section preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. The mouthpiece section may have an external diameter of between about 5 millimetres and about 10 millimetres, or between about 6 millimetres and about 8 millimetres. In a preferred embodiment, the mouthpiece section has an external diameter of approximately 7.2 millimetres.

The mouthpiece section preferably has a length of at least about 5 millimetres, more preferably at least about 8 millimetres, more preferably at least about 10 millimetres. Alternatively or in addition, the mouthpiece section preferably has a length of less than about 25 millimetres, more preferably less than about 20 millimetres, more preferably less than about 15 millimetres.

In some embodiments, the mouthpiece section preferably has a length from about 5 millimetres to about 25 millimetres, more preferably from about 8 millimetres to about 25 millimetres, even more preferably from about 10 millimetres to about 25 millimetres. In other embodiments, the mouthpiece section preferably has a length from about 5 millimetres to about 10 millimetres, more preferably from about 8 millimetres to about 20 millimetres, even more preferably from about 10 millimetres to about 20 millimetres. In further embodiments, the mouthpiece section preferably has a length from about 5 millimetres to about 15 millimetres, more preferably from about 8 millimetres to about 15 millimetres, even more preferably from about 10 millimetres to about 15 millimetres.

For example, the mouthpiece section may have a length of between about 5 millimetres and about 25 millimetres, or between about 8 millimetres and about 20 millimetres, or between about 10 millimetres and about 15 millimetres. In a preferred embodiment, the mouthpiece section has a length of approximately 12 millimetres.

In certain preferred embodiments of the invention, the mouthpiece section has a length of at least 10 millimetres. In such embodiments, the mouthpiece section is therefore relatively long compared to the mouthpiece section provided in prior art articles. The provision of a relatively long mouthpiece section in the aerosol-generating articles of the present invention may provide several benefits to the consumer. The mouthpiece section is typically more resilient to deformation or better adapted to recover its initial shape after deformation than other elements that may be provided downstream of the rod of aerosol-generating substrate, such as an aerosolcooling element or support element. Increasing the length of the mouthpiece section is therefore found to provide for improved grip by the consumer and to facilitate insertion of the aerosolgenerating article into a heating device. A longer mouthpiece may additionally be used to provide a higher level of filtration and removal of undesirable aerosol constituents such as phenols, so that a higher quality aerosol can be delivered. In addition, the use of a longer mouthpiece section enables a more complex mouthpiece to be provided since there is more space for the incorporation of mouthpiece components such as capsules, threads and restrictors.

In particularly preferred embodiments of the invention, a mouthpiece section having a length of at least 10 millimetres is combined with a relatively short aerosol-cooling element, for example, an aerosol-cooling element having a length of less than 10 millimetres. This combination has been found to provide a more rigid mouthpiece which reduces the risk of deformation of the aerosol-cooling element during use and to contribute to a more efficient puffing action by the consumer.

The length of the mouthpiece section may be at least 0.40 times the total length of the intermediate hollow section, preferably at least 0.50 times the length of the intermediate hollow section, more preferably at least 0.60 times the length of the intermediate hollow section, more preferably at least 0.75 times the length of the intermediate hollow section. The ratio between the length of the mouthpiece section and the total length of the intermediate hollow section is therefore at least about 0.40, preferably at least about 0.50, more preferably at least about 0.60 and most preferably at least about 0.75.

A ratio between the length of the mouthpiece section and the length of the rod of aerosolgenerating substrate may be from about 0.50 to about 1.50.

Preferably, a ratio between the length of the mouthpiece section and the length of the rod of aerosol-generating substrate is at least about 0.60, more preferably at least about 0.70, even more preferably at least about 0.80. In preferred embodiments, a ratio between the length of the mouthpiece section and the length of the rod of aerosol-generating substrate is less than about 1.40, more preferably less than about 1.30, even more preferably less than about 1.20. In some embodiments, a ratio between the length of the mouthpiece section and the length of the rod of aerosol-generating substrate is from about 0.60 to about 1 .40, preferably from about 0.70 to about 1 .40, more preferably from about 0.80 to about 1.40. In other embodiments, a ratio between the length of the mouthpiece section and the length of the rod of aerosol-generating substrate is from about 0.60 to about 1.30, preferably from about 0.70 to about 1.30, more preferably from about 0.80 to about 1 .30. In further embodiments, a ratio between the length of the mouthpiece section and the length of the rod of aerosol-generating substrate is from about 0.60 to about 1.20, preferably from about 0.70 to about 1.20, more preferably from about 0.80 to about 1.20.

In a particularly preferred embodiments, a ratio between the length of the mouthpiece section and the length of the rod of aerosol-generating substrate is about 1 .00.

A ratio between the length of the mouthpiece section and the overall length of the aerosolgenerating article substrate may be from about 0.20 to about 0.35.

Preferably, a ratio between the length of the mouthpiece section and the overall length of the aerosol-generating article is at least about 0.22, more preferably at least about 0.24, even more preferably at least about 0.26. A ratio between the length of the mouthpiece section and the overall length of the aerosol-generating article is preferably less than about 0.34, more preferably less than about 0.32, even more preferably less than about 0.30.

In some embodiments, a ratio between the length of the mouthpiece section and the overall length of the aerosol-generating article is preferably from about 0.22 to about 0.34, more preferably from about 0.24 to about 0.34, even more preferably from about 0.26 to about 0.34. In other embodiments, a ratio between the length of the mouthpiece section and the overall length of the aerosol-generating article is preferably from about 0.22 to about 0.32, more preferably from about 0.24 to about 0.32, even more preferably from about 0.26 to about 0.32. In further embodiments, a ratio between the length of the mouthpiece section and the overall length of the aerosol-generating article is preferably from about 0.22 to about 0.30, more preferably from about 0.24 to about 0.30, even more preferably from about 0.26 to about 0.30.

In a particularly preferred embodiment, a ratio between the length of the mouthpiece section and the overall length of the aerosol-generating article is about 0.27.

In some embodiments, the mouthpiece section comprises a single mouthpiece filter segment that extends all the way to the mouth end of the aerosol-generating article. In some embodiments, the mouthpiece section comprises a single mouthpiece filter segment and a mouth end cavity at the downstream end of the mouthpiece section.

In embodiments containing a single mouthpiece filter segment, preferably, the mouthpiece filter segment has an RTD of less than about 25 millimetres H2O. More preferably, the mouthpiece filter segment has an RTD of less than about 20 millimetres H2O. More preferably, the mouthpiece section has an RTD of less than about 15 millimetres H2O.

Values of RTD from about 10 millimetres H2O to about 25 millimetres H2O or from about 10 millimetres H2O to about 15 millimetres H2O are particularly preferred because a mouthpiece filter segment having one such RTD is expected to contribute minimally to the overall RTD of the aerosol-generating article substantially does not exert a filtration action on the aerosol being delivered to the consumer.

The one or more hollow tubular elements in the downstream section provide a negligible

RTD, such that in these embodiments the mouthpiece filter segment provides the major contribution to the RTD of the downstream section. Preferably, the downstream section has an

RTD of less than about 25 millimetres H2O. More preferably, the downstream section has an

RTD of less than about 20 millimetres H2O. More preferably, the downstream section has an

RTD of less than about 15 millimetres H2O. Values of RTD from about 10 millimetres H2O to about 25 millimetres H2O or from about 10 millimetres H2O to about to about 15 millimetres H2O are particularly preferred.

The mouthpiece filter segment preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. The mouthpiece filter segment may have an external diameter of between about 5 millimetres and about 10 millimetres, or between about 6 millimetres and about 8 millimetres. In a preferred embodiment, the mouthpiece section has an external diameter of approximately 7.2 millimetres.

The mouthpiece filter segment preferably has a length of at least about 5 millimetres, more preferably at least about 8 millimetres, more preferably at least about 10 millimetres. Alternatively or in addition, the mouthpiece filter segment preferably has a length of less than about 25 millimetres, more preferably less than about 20 millimetres, more preferably less than about 15 millimetres.

In some embodiments, the mouthpiece filter segment preferably has a length from about 5 millimetres to about 25 millimetres, more preferably from about 8 millimetres to about 25 millimetres, even more preferably from about 10 millimetres to about 25 millimetres. In other embodiments, the mouthpiece filter segment preferably has a length from about 5 millimetres to about 10 millimetres, more preferably from about 8 millimetres to about 20 millimetres, even more preferably from about 10 millimetres to about 20 millimetres. In further embodiments, the mouthpiece filter segment preferably has a length from about 5 millimetres to about 15 millimetres, more preferably from about 8 millimetres to about 15 millimetres, even more preferably from about 10 millimetres to about 15 millimetres.

For example, the mouthpiece filter segment may have a length of between about 5 millimetres and about 25 millimetres, or between about 8 millimetres and about 20 millimetres, or between about 10 millimetres and about 15 millimetres. In a preferred embodiment, the mouthpiece filter segment has a length of approximately 12 millimetres.

In certain preferred embodiments of the invention, the mouthpiece filter segment has a length of at least 10 millimetres. In such embodiments, the mouthpiece filter segment is therefore relatively long compared to the mouthpiece filter segment provided in prior art articles. The provision of a relatively long mouthpiece filter segment in the aerosol-generating articles of the present invention may provide several benefits to the consumer. The mouthpiece filter segment is typically more resilient to deformation or better adapted to recover its initial shape after deformation than other elements that may be provided downstream of the rod of aerosolgenerating substrate, such as an aerosol-cooling element or support element. Increasing the length of the mouthpiece filter segment is therefore found to provide for improved grip by the consumer and to facilitate insertion of the aerosol-generating article into a heating device. A longer mouthpiece may additionally be used to provide a higher level of filtration and removal of undesirable aerosol constituents such as phenols, so that a higher quality aerosol can be delivered. In addition, the use of a longer mouthpiece filter segment enables a more complex mouthpiece to be provided since there is more space for the incorporation of mouthpiece components such as capsules, threads and restrictors.

In particularly preferred embodiments of the invention, a mouthpiece filter segment having a length of at least 10 millimetres is combined with a relatively short aerosol-cooling element, for example, an aerosol-cooling element having a length of less than 10 millimetres. This combination has been found to provide a more rigid mouthpiece which reduces the risk of deformation of the aerosol-cooling element during use and to contribute to a more efficient puffing action by the consumer.

The length of the mouthpiece filter segment may be at least 0.30 times the total length of the intermediate hollow section, preferably at least 0.40 times the total length of the intermediate hollow section, more preferably at least 0.50 times the length of the intermediate hollow section, even more preferably at least 0.60 times the length of the intermediate hollow section, most preferably at least 0.75 times the length of the intermediate hollow section. The ratio between the length of the mouthpiece filter segment and the total length of the intermediate hollow section is therefore at least about 0.30, preferably at least about 0.40, more preferably at least about 0.50, even more preferably at least about 0.60 and most preferably at least about 0.75.

A ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate may be from about 0.40 to about 1.50.

Preferably, a ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate is at least about 0.40, more preferably at least about 0.60, even more preferably at least about 0.70, even more preferably at least about 0.80. In preferred embodiments, a ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate is less than about 1.40, more preferably less than about 1.30, even more preferably less than about 1.20.

In some embodiments, a ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate is preferably from about 0.40 to about 1.40, more preferably about 0.60 to about 1.40, even more preferably from about 0.70 to about 1.40, most preferably from about 0.80 to about 1 .40. In other embodiments, a ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate is preferably from about 0.40 to about 1.30, more preferably from about 0.60 to about 1.30, even more preferably from about 0.70 to about 1 .30, most preferably from about 0.80 to about 1 .30. In further embodiments, a ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate is from about 0.40 to about 1.20, more preferably from about 0.60 to about 1.20, even more preferably from about 0.70 to about 1.20, most preferably from about 0.80 to about 1.20.

In a particularly preferred embodiment, a ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate is about 1.00. In another particularly preferred embodiment, a ratio between the length of the mouthpiece filter segment and the length of the rod of aerosol-generating substrate is about 0.42.

A ratio between the length of the mouthpiece filter segment and the overall length of the aerosol-generating article may be from about 0.11 to about 0.35.

Preferably, a ratio between the length of the mouthpiece filter segment and the overall length of the aerosol-generating article is at least about 0.11 , more preferably at least about 0.22, even more preferably at least about 0.24, most preferably at least about 0.26. A ratio between the length of the mouthpiece filter segment and the overall length of the aerosol-generating article is preferably less than about 0.34, more preferably less than about 0.32, even more preferably less than about 0.3.

In some embodiments, a ratio between the length of the mouthpiece filter segment and the overall length of the aerosol-generating article is preferably from about 0.11 to about 0.34, more preferably from about 0.22 to about 0.34, even more preferably from about 0.24 to about 0.34, most preferably from about 0.26 to about 0.34. In other embodiments, a ratio between the length of the mouthpiece filter segment and the overall length of the aerosol-generating article is preferably from about 0.11 to about 0.32, more preferably from about 0.22 to about 0.32, even more preferably from about 0.24 to about 0.32, most preferably from about 0.26 to about 0.32. In further embodiments, a ratio between the length of the mouthpiece filter segment and the overall length of the aerosol-generating article is preferably from about 0.11 to about 0.3, more preferably from about 0.22 to about 0.3, even more preferably from about 0.24 to about 0.3, most preferably from about 0.26 to about 0.3.

In a particularly preferred embodiment, a ratio between the length of the mouthpiece filter segment and the overall length of the aerosol-generating article is about 0.27. In another particularly preferred embodiment, a ratio between the length of the mouthpiece filter and the overall length of the aerosol-generating article is about 0.11.

The rod-shaped aerosol-generating element of the invention comprises an aerosolgenerating substrate. The aerosol-generating substrate comprises an aerosol-generating film. The aerosol-generating film comprises one or more cellulose based film-forming agents and one or more aerosol formers.

The aerosol-generating film may remain solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius. As described further below, this may advantageously reduce or eliminate crusting in aerosol-generating articles.

For example, the aerosol-generating film may remain solid when heated to a temperature of between 200 degrees Celsius and 320 degrees Celsius, between 220 degrees Celsius and 300 degrees Celsius, or between 240 degrees Celsius and 280 degrees Celsius.

As used herein, the term “film” is used to describe a solid aerosol-generating substrate having a thickness that is substantially less than the width or length thereof.

The term “exposed surface area of the film” is used herein to denote the cumulative surface area of the various surfaces of an aerosol-generating film that, during use, may become exposed to the gaseous airflow through the aerosol-generating article containing the film.

The “weight” of the aerosol-generating film of aerosol-generating articles according to the invention will generally correspond to the weight of the components of the corresponding filmforming composition minus the weight of water evaporated during the drying step. If a film is self- supporting, the film can be weighed on its own. If a film is disposed on a support, the film and the support may be weighed and the weight of the support, measured prior to deposition of the film, is subtracted from the combined weight of the film and the support.

Unless stated otherwise, percentages by weight of components of the aerosol-generating film recited herein are based on the total weight of the aerosol-generating film.

As used herein, the term “thickness” is used to describe the minimum dimension between opposite, substantially parallel surfaces of an aerosol-generating film. The thickness of the aerosol-generating film may substantially correspond to the thickness to which a corresponding film-forming composition is cast or extruded, as the cast or extruded film-forming composition substantially does not contract during drying, despite the loss of water. The aerosol-generating film may have a thickness of greater than or equal to 0.05 millimetres, greater than or equal to 0.1 millimetres, greater than or equal to 0.2 millimetres, or greater than or equal to 0.3 millimetres.

The aerosol-generating film may have a thickness of less than or equal to 1.2 millimetres, less than or equal to 1 millimetre, less than or equal to 0.8 millimetres, less than or equal to 0.6 millimetres, or less than or equal to 0.4 millimetres.

The aerosol-generating film may have a thickness of between 0.05 millimetres and 1.2 millimetres, between 0.05 millimetres and 1 millimetre, between 0.05 millimetres and 0.8 millimetres, between 0.05 millimetres and 0.6 millimetres, or between 0.05 millimetres and 0.4 millimetres.

The aerosol-generating film may have a thickness of between 0.1 millimetres and 1.2 millimetres, between 0.1 millimetres and 1 millimetre, between 0.1 millimetres and 0.8 millimetres, between 0.1 millimetres and 0.6 millimetres, or between 0.1 millimetres and 0.4 millimetres.

The aerosol-generating film may have a thickness of between 0.2 millimetres and 1.2 millimetres, between 0.2 millimetres and 1 millimetre, between 0.2 millimetres and 0.8 millimetres, between 0.2 millimetres and 0.6 millimetres, or between 0.2 millimetres and 0.4 millimetres.

The aerosol-generating film may have a thickness of between 0.3 millimetres and 1.2 millimetres, between 0.3 millimetres and 1 millimetre, between 0.3 millimetres and 0.8 millimetres, between 0.3 millimetres and 0.6 millimetres, or between 0.3 millimetres and 0.4 millimetres.

The aerosol-generating film may have a basis weight of greater than or equal to 85 grams per square metre, greater than or equal to 100 grams per square metre, greater than or equal to 120 grams per square metre, or greater than or equal to 140 grams per square metre.

The aerosol-generating film may have a basis weight of less than or equal to 300 grams per square metre, less than or equal to 280 grams per square metre, or less than or equal to 260 grams per square metre.

The aerosol-generating film may have a basis weight of between 85 grams per square metre and 300 grams per square metre, between 85 grams per square metre and 280 grams per square metre, or between 85 grams per square metre and 260 grams per square metre.

The aerosol-generating film may have a basis weight of between 100 grams per square metre and 300 grams per square metre, between 100 grams per square metre and 280 grams per square metre, or between 100 grams per square metre and 260 grams per square metre.

The aerosol-generating film may have a basis weight of between 120 grams per square metre and 300 grams per square metre, between 120 grams per square metre and 280 grams per square metre, or between 120 grams per square metre and 260 grams per square metre. The aerosol-generating film may have a basis weight of between 140 grams per square metre and 300 grams per square metre, between 140 grams per square metre and 280 grams per square metre, or between 140 grams per square metre and 260 grams per square metre.

The aerosol-generating film may be formed by any suitable method. For example, the aerosol-generating film may be formed by batch casting, continuous casting or extrusion.

The aerosol-generating film may be self-supporting. In other words, the properties of the aerosol-generating film may be such that, even if the aerosol-generating film is formed by casting a slurry onto a support surface, the aerosol-generating film can be separated from the support surface.

The aerosol-generating film may be disposed on a support or the aerosol-generating film may be sandwiched between other materials. This may enhance the mechanical stability of the aerosol-generating film. For example, the aerosol-generating film may be disposed on a laminar support.

The aerosol-generating film may be cut or otherwise divided into a plurality of strips or shreds that may be wrapped to form an aerosol-generating rod for inclusion in the aerosolgenerating article.

The aerosol-generating film may be gathered to form an aerosol-generating rod for inclusion in the aerosol-generating article.

The aerosol-generating film may be textured. This may facilitate gathering of the aerosolgenerating film to form an aerosol-generating rod for inclusion in the aerosol-generating article.

The term “textured” is used to describe an aerosol-generating film that has been crimped, embossed, debossed, perforated or otherwise deformed. Textured aerosol-generating film may comprise a plurality of spaced-apart indentations, protrusions, perforations or a combination thereof.

The aerosol-generating film may be crimped.

As used herein, the term “crimped” is intended to be synonymous with the term “creped” and is used to describe a aerosol-generating film having a plurality of substantially parallel ridges or corrugations.

The crimped aerosol-generating film may have a plurality of ridges or corrugations substantially parallel to the cylindrical axis of the aerosol-generating rod. This may advantageously facilitate gathering of the crimped aerosol-generating film to form the aerosolgenerating rod.

The aerosol-generating film may be textured using suitable known machinery for texturing filter tow, paper and other materials.

The aerosol-generating film may be crimped using a crimping unit of the type described in CH-A-691156, which comprises a pair of rotatable crimping rollers. However, it will be appreciated that the aerosol-generating film may be textured using other suitable machinery and processes that deform or perforate the aerosol-generating film.

The aerosol-generating film may be incorporated directly into an aerosol-generating rod for inclusion in the aerosol-generating article.

The aerosol-generating film may be applied to a laminar support before being incorporated into an aerosol-generating rod for inclusion in an aerosol-generating article. For example, the aerosol-generating film may be applied to the surface of a sheet material. Suitable sheet materials for use as the laminar support include, but are not limited, to: paper; cardboard; and homogenised plant material. For example, the aerosol-generating film may be applied to a paper sheet, an aluminium coated paper sheet, or a polyethylene coated paper sheet.

The laminar support with the aerosol-generating film applied thereto may be cut or otherwise divided into a plurality of strips or shreds as described above.

The laminar support with the aerosol-generating film applied thereto may be gathered as described above.

The laminar support with the aerosol-generating film applied thereto may be textured as described above.

The aerosol-generating film may be applied to a tubular support before being incorporated into an aerosol-generating rod for inclusion in the aerosol-generating article. For example, the aerosol-generating film may be applied to the inner surface of a hollow tubular support.

Preferably, the aerosol-generating film may comprise nicotine.

As used herein, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt. In some embodiments in which the aerosol-generating film may comprise a nicotine base or a nicotine salt, the amounts of nicotine recited herein are the amount of free base nicotine or amount of protonated nicotine, respectively.

The aerosol-generating film may comprise natural nicotine, or synthetic nicotine, or a combination of natural nicotine and synthetic nicotine.

The nicotine may comprise one or more nicotine salts. The one or more nicotine salts may be selected from the list consisting of nicotine lactate, nicotine citrate, nicotine pyruvate, nicotine bitartrate, nicotine benzoate, nicotine pectate, nicotine alginate, and nicotine salicylate.

The nicotine may comprise an extract of tobacco.

The aerosol-generating film may have a nicotine content of greater than or equal to 0.5 percent by weight, greater than or equal to 1 percent by weight, greater than or equal to 1 .5 percent by weight, or greater than or equal to 2 percent by weight.

The aerosol-generating film may have a nicotine content of less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight. The aerosol-generating film may have a nicotine content of between 0.5 percent by weight and 10 percent by weight, between 0.5 percent by weight and 8 percent by weight, between 0.5 percent by weight and 6 percent by weight, or between 0.5 percent by weight and 4 percent by weight.

The aerosol-generating film may have a nicotine content of between 1 percent by weight and 10 percent by weight, between 1 percent by weight and 8 percent by weight, between 1 percent by weight and 6 percent by weight, or between 1 percent by weight and 4 percent by weight.

The aerosol-generating film may have a nicotine content of between 1 .5 percent by weight and 10 percent by weight, between 1 .5 percent by weight and 8 percent by weight, between 1 .5 percent by weight and 6 percent by weight, or between 1.5 percent by weight and 4 percent by weight.

The aerosol-generating film may have a nicotine content of between 2 percent by weight and 10 percent by weight, between 2 percent by weight and 8 percent by weight, between 2 percent by weight and 6 percent by weight, or between 2 percent by weight and 4 percent by weight.

The aerosol-generating film comprises one or more aerosol formers.

The term “aerosol former” is used to describe a compound that, in use, facilitates formation of the aerosol, and that preferably is substantially resistant to thermal degradation at the operating temperature of an aerosol-generating article or aerosol-generating system comprising the aerosol-generating film.

Examples of suitable aerosol formers include: polyhydric alcohols, such as 1 ,3-butanediol, glycerine, 1 ,3-propanediol, propylene glycol, and triethylene glycol; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

Preferably, the one or more aerosol formers comprise one or more polyhydric alcohols selected from 1 ,3-butanediol, glycerine, 1 ,3-propanediol, propylene glycol, and triethylene glycol.

More preferably, the one or more aerosol formers comprise one or more or more polyhydric alcohols selected from glycerine and propylene glycol. Even more preferably, the one or more aerosol formers comprise glycerine.

Most preferably, the one or more aerosol formers may be glycerine.

The aerosol-generating film may have a total aerosol former content of greater than or equal to 45 percent by weight.

The term “total aerosol former content” is used to describe the combined content of all aerosol formers in the aerosol-generating film. The aerosol-generating film may have a total aerosol former content of greater than or equal to 46 percent by weight, greater than or equal to 48 percent by weight, greater than or equal to 50 percent by weight, or greater than or equal to 52 percent by weight.

The aerosol-generating film may have a total aerosol former content of less than or equal to 62 percent by weight, less than or equal to 60 percent by weight, less than or equal to 58 percent by weight, less than or equal to 56 percent by weight, or less than or equal to 54 percent by weight.

The aerosol-generating film may have a total aerosol former content of between 45 percent by weight and 62 percent by weight, between 45 percent by weight and 60 percent by weight, between 45 percent by weight and 58 percent by weight, between 45 percent by weight and 56 percent by weight, or between 45 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total aerosol former content of between 46 percent by weight and 62 percent by weight, between 46 percent by weight and 60 percent by weight, between 46 percent by weight and 58 percent by weight, between 46 percent by weight and 56 percent by weight, or between 46 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total aerosol former content of between 48 percent by weight and 62 percent by weight, between 48 percent by weight and 60 percent by weight, between 48 percent by weight and 58 percent by weight, between 48 percent by weight and 56 percent by weight, or between 48 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total aerosol former content of between 50 percent by weight and 62 percent by weight, between 50 percent by weight and 60 percent by weight, between 50 percent by weight and 58 percent by weight, between 50 percent by weight and 56 percent by weight, or between 50 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total aerosol former content of between 52 percent by weight and 62 percent by weight, between 52 percent by weight and 60 percent by weight, between 52 percent by weight and 58 percent by weight, between 52 percent by weight and 56 percent by weight, or between 52 percent by weight and 54 percent by weight.

Preferably, the aerosol-generating film may comprise one or more polyhydric alcohols.

The aerosol-generating film may have a total polyhydric alcohol content of greater than or equal to 45 percent by weight, greater than or equal to 46 percent by weight, greater than or equal to 48 percent by weight, greater than or equal to 50 percent by weight, or greater than or equal to 52 percent by weight.

The term “total polyhydric alcohol content” is used to describe the combined content of all polyhydric alcohols in the aerosol-generating film.

The aerosol-generating film may have a total polyhydric alcohol content of less than or equal to 62 percent by weight, less than or equal to 60 percent by weight, less than or equal to 58 percent by weight, less than or equal to 56 percent by weight, or less than or equal to 54 percent by weight.

The aerosol-generating film may have a total polyhydric alcohol content of between 45 percent by weight and 62 percent by weight, between 45 percent by weight and 60 percent by weight, between 45 percent by weight and 58 percent by weight, between 45 percent by weight and 56 percent by weight, or between 45 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total polyhydric alcohol content of between 46 percent by weight and 62 percent by weight, between 46 percent by weight and 60 percent by weight, between 46 percent by weight and 58 percent by weight, between 46 percent by weight and 56 percent by weight, or between 46 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total polyhydric alcohol content of between 48 percent by weight and 62 percent by weight, between 48 percent by weight and 60 percent by weight, between 48 percent by weight and 58 percent by weight, between 48 percent by weight and 56 percent by weight, or between 48 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total polyhydric alcohol content of between 50 percent by weight and 62 percent by weight, between 50 percent by weight and 60 percent by weight, between 50 percent by weight and 58 percent by weight, between 50 percent by weight and 56 percent by weight, or between 50 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total polyhydric alcohol content of between 52 percent by weight and 62 percent by weight, between 52 percent by weight and 60 percent by weight, between 52 percent by weight and 58 percent by weight, between 52 percent by weight and 56 percent by weight, or between 52 percent by weight and 54 percent by weight.

Preferably, the aerosol-generating film comprises one or more polyhydric alcohols selected from 1 ,3-butanediol, glycerine, 1 ,3-propanediol, propylene glycol, and triethylene glycol.

More preferably, the aerosol-generating film comprises one or more polyhydric alcohols selected from glycerine and propylene glycol.

Most preferably, the aerosol-generating film comprises glycerine.

The aerosol-generating film may have a glycerine content of greater than or equal to 35 percent by weight, greater than or equal to 40 percent by weight, greater than or equal to 45 percent by weight, greater than or equal to 46 percent by weight, greater than or equal to 48 percent by weight, greater than or equal to 50 percent by weight, or greater than or equal to 52 percent by weight.

The aerosol-generating film may have a glycerine content of less than or equal to 62 percent by weight, less than or equal to 60 percent by weight, less than or equal to 58 percent by weight, less than or equal to 56 percent by weight, or less than or equal to 54 percent by weight. The aerosol-generating film may have a glycerine content of between 35 percent by weight and 62 percent by weight, between 35 percent by weight and 60 percent by weight, between 35 percent by weight and 58 percent by weight, between 35 percent by weight and 56 percent by weight, or between 35 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total glycerine content of between 40 percent by weight and 62 percent by weight, between 40 percent by weight and 60 percent by weight, between 40 percent by weight and 58 percent by weight, between 40 percent by weight and 56 percent by weight, or between 40 percent by weight and 54 percent by weight.

The aerosol-generating film may have a glycerine content of between 45 percent by weight and 62 percent by weight, between 45 percent by weight and 60 percent by weight, between 45 percent by weight and 58 percent by weight, between 45 percent by weight and 56 percent by weight, or between 45 percent by weight and 54 percent by weight.

The aerosol-generating film may have a glycerine content of between 46 percent by weight and 62 percent by weight, between 46 percent by weight and 60 percent by weight, between 46 percent by weight and 58 percent by weight, between 46 percent by weight and 56 percent by weight, or between 46 percent by weight and 54 percent by weight.

The aerosol-generating film may have a glycerine content of between 48 percent by weight and 62 percent by weight, between 48 percent by weight and 60 percent by weight, between 48 percent by weight and 58 percent by weight, between 48 percent by weight and 56 percent by weight, or between 48 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total glycerine content of between 50 percent by weight and 62 percent by weight, between 50 percent by weight and 60 percent by weight, between 50 percent by weight and 58 percent by weight, between 50 percent by weight and 56 percent by weight, or between 50 percent by weight and 54 percent by weight.

The aerosol-generating film may have a total glycerine content of between 52 percent by weight and 62 percent by weight, between 52 percent by weight and 60 percent by weight, between 52 percent by weight and 58 percent by weight, between 52 percent by weight and 56 percent by weight, or between 52 percent by weight and 54 percent by weight.

Preferably, the aerosol-generating film may comprise one or more carboxylic acids.

The aerosol-generating film may comprise a plurality of carboxylic acids. That is, the aerosol-generating film may comprise two or more carboxylic acids. For example, the aerosolgenerating film may comprise two carboxylic acids, three carboxylic acids, four carboxylic acids, or five carboxylic acids.

It has surprisingly been found that inclusion of one or more carboxylic acids in the aerosolgenerating film of aerosol-generating articles may advantageously improve the stability of the aerosol-generating film during storage of aerosol-generating articles. It has surprisingly been found that inclusion of one or more carboxylic acids in the aerosol-generating film of aerosolgenerating articles may advantageously improve the stability of nicotine in the aerosol-generating film during storage of aerosol-generating articles. In particular, it has surprisingly been found that inclusion of one or more carboxylic acids in the aerosol-generating film of aerosol-generating articles may advantageously inhibit corrosion of components of aerosol-generating articles. In particular, it has surprisingly been found that inclusion of one or more carboxylic acids in the aerosol-generating film of aerosol-generating articles may advantageously inhibit corrosion of metal components of aerosol-generating articles. In particular, it has surprisingly been found that inclusion of one or more carboxylic acids in the aerosol-generating film of aerosol-generating articles may advantageously inhibit corrosion of the susceptor of aerosol-generating articles. In some embodiments, the susceptor is in direct contact with the aerosol-generating substrate.

Without wishing to be bound by theory, it is believed that, when included in the aerosolgenerating film, carboxylic acids that do not contain any non-carboxyl alkyl hydroxyl groups are less prone to oxidise other components of aerosol-generating articles than carboxylic acids that do contain non-carboxyl alkyl hydroxyl groups. Without wishing to be bound by theory, it is believed that when included in the aerosol-generating film, carboxylic acids that do not contain any ketone groups are less prone to oxidise other components of aerosol-generating articles than carboxylic acids that do contain ketone groups. It is believed that inclusion of one or more carboxylic acids that do not contain any non-carboxyl alkyl hydroxyl groups and do not contain any ketone groups in the aerosol-generating film thereby inhibits corrosion of components of aerosol-generating articles.

Without wishing to be bound by theory, it is believed that, when included in the aerosolgenerating film, carboxylic acids having a pKa of less than or equal to 3.5 are less prone to oxidise other components of aerosol-generating articles than carboxylic acids having pKa of greater than 3.5. It is believed that inclusion of one or more carboxylic acids having a pKa of less than or equal to 3.5 in the aerosol-generating film thereby inhibits corrosion of components of aerosolgenerating articles.

The aerosol-generating film may comprise one or more carboxylic acids that: (i) do not contain any non-carboxyl alkyl hydroxyl groups and do not contain any ketone groups; or (ii) have a pKa at 25°C in water of less than or equal to 3.5; or (iii) do not contain any non-carboxyl alkyl hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of less than or equal to 3.5.

The aerosol-generating film may comprise a plurality of carboxylic acids that do not contain any non-carboxyl alky hydroxyl groups and do not contain any ketone groups. For example, the aerosol-generating film may comprise benzoic acid and succinic acid. The aerosol-generating film may comprise one or more carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5.

As used herein with reference to the invention, the term “carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5” is used to describe monoprotic carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5 and polyprotic carboxylic acids having a pKa1 at 25°C in water of less than or equal to 3.5.

For example, the aerosol-generating film may comprise one or more carboxylic acids selected from citric acid, fumaric acid, maleic acid, malic acid, oxalic acid, and salicylic acid.

The aerosol-generating film may comprise a plurality of carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5. For example, the aerosol-generating film may comprise citric acid and malic acid.

The aerosol-generating film may comprise one or more carboxylic acids that do not contain any non-carboxyl alky hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of less than or equal to 3.5. For example, the aerosol-generating film may comprise one or more carboxylic acids selected from fumaric acid, maleic acid, oxalic acid, and salicylic acid.

The aerosol-generating film may comprise a plurality of carboxylic acids that do not contain any non-carboxyl alky hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of less than or equal to 3.5. For example, the aerosol-generating film may comprise fumaric acid and maleic acid.

The aerosol-generating film may comprise one or more carboxylic acids having a pKa at 25°C in water of greater than or equal to 3.6.

As used herein with reference to the invention, the term “carboxylic acids having a pKa at 25°C in water of greater than or equal to 3.6” is used to describe monoprotic carboxylic acids having a pKa at 25°C in water of greater than or equal to 3.6 and polyprotic carboxylic acids having a pKa1 at 25°C in water of greater than or equal to 3.6.

The aerosol-generating film may comprise one or more carboxylic acids that do not contain any non-carboxyl alky hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of greater than or equal to 3.6. For example, the aerosol-generating film may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, and succinic acid.

The aerosol-generating film may comprise a plurality of carboxylic acids that do not contain any non-carboxyl alky hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of greater than or equal to 3.6. For example, the aerosol-generating film may comprise acetic acid and benzoic acid. The aerosol-generating film may further comprise one or more carboxylic acids that contain a non-carboxyl alky hydroxyl group and have a pKa at 25°C in water of greater than or equal to 3.6. For example, the aerosol-generating film may further comprise lactic acid.

The aerosol-generating film may further comprise one or more carboxylic acids that contain a ketone group and have a pKa at 25°C in water of greater than or equal to 3.6. For example, the aerosol-generating film may further comprise levulinic acid.

The aerosol-generating film may comprise a plurality of carboxylic acids having a pKa at 25°C in water of greater than or equal to 3.6. For example, the aerosol-generating film may comprise benzoic acid and lactic acid.

The aerosol-generating film may comprise one or more carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5 and one or more carboxylic acids having a pKa at 25°C in water of greater than or equal to 3.6.

For example, the aerosol-generating film may comprise one or more carboxylic acids selected from fumaric acid, maleic acid, and malic acid and one or more carboxylic acids selected from acetic acid, benzoic acid, lactic acid, and levulinic acid.

For example, the aerosol-generating film may comprise fumaric acid and one or more carboxylic acids selected from acetic acid, benzoic acid, lactic acid, and levulinic acid.

The aerosol-generating film may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, undecanoic acid, and C1-C 10 saturated alkyl mono-carboxylic acids.

The aerosol-generating film may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid.

The aerosol-generating film may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid.

The aerosol-generating film may comprise one or more carboxylic acids selected from acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid.

The aerosol-generating film may comprise one or more carboxylic acids selected from acetic acid, benzoic acid, citric acid, fumaric acid, and maleic acid.

The aerosol-generating film may comprise one or more carboxylic acids selected from fumaric acid, maleic acid, and malic acid.

Preferably, the aerosol-generating film comprises one or more carboxylic acids selected from fumaric acid and maleic acid.

More preferably, the aerosol-generating film comprises fumaric acid. The aerosol-generating film may further comprise one or more carboxylic acids selected from lactic acid and levulinic acid. Advantageously, including one or more carboxylic acids in the aerosol-generating substrate may create a nicotine salt. Advantageously, the present inventors have found that lactic acid and levulnic acid are particularly good carboxylic acids for creating nicotine salts.

The aerosol-generating film has a total carboxylic acid content of greater than or equal to 0.5 percent by weight.

The term “total carboxylic acid content” is used to describe the combined content of all carboxylic acids in the aerosol-generating film. For example, where the aerosol-generating film comprises a plurality of carboxylic acids consisting of benzoic acid and fumaric acid, the term “total carboxylic acid content” describes the combined benzoic acid content and fumaric acid content of the aerosol-generating film.

The aerosol-generating film may have a total carboxylic acid content of greater than or equal to 1 percent by weight, greater than or equal to 1.5 percent by weight, or greater than or equal to 2 percent by weight.

The aerosol-generating film may have a total carboxylic acid content of less than or equal to 8 percent by weight, less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight.

The aerosol-generating film may have a total carboxylic acid content of between 0.5 percent by weight and 8 percent by weight, between 0.5 percent by weight and 6 percent by weight, or between 0.5 percent by weight and 4 percent by weight.

The aerosol-generating film may have a total carboxylic acid content of between 1 percent by weight and 8 percent by weight, between 1 percent by weight and 6 percent by weight, or between 1 percent by weight and 4 percent by weight.

The aerosol-generating film may have a total carboxylic acid content of between 1 .5 percent by weight and 8 percent by weight, between 1 .5 percent by weight and 6 percent by weight, or between 1.5 percent by weight and 4 percent by weight.

The aerosol-generating film may have a total carboxylic acid content of between 2 percent by weight and 8 percent by weight, between 2 percent by weight and 6 percent by weight, or between 2 percent by weight and 4 percent by weight.

The molar ratio of total carboxylic acid to nicotine in the aerosol-generating film may be greater than or equal to 0.5:1 , greater than or equal to 1 :1 , greater than or equal to 1.5:1 , or greater than or equal to 2:1 .

The molar ratio of total carboxylic acid to nicotine in the aerosol-generating film may be less than or equal to 5:1 , less than or equal to 4.5:1 , less than or equal to 4:1 , or less than or equal to 3.5:1. The molar ratio of total carboxylic acid to nicotine in the aerosol-generating film may be between 0.5:1 and 5:1 , between 0.5:1 and 4.5:1 , between 0.5:1 and 4:1 , or between 0.5:1 and 3.5:1.

The molar ratio of total carboxylic acid to nicotine in the aerosol-generating film may be between 1 :1 and 5:1 , between 1 :1 and 4.5:1 , between 1 :1 and 4:1 , or between 1 :1 and 3.5:1.

The molar ratio of total carboxylic acid to nicotine in the aerosol-generating film may be between 1.5:1 and 5:1 , between 1.5:1 and 4.5:1 , between 1.5:1 and 4:1 , or between 1.5:1 and 3.5:1.

The molar ratio of total carboxylic acid to nicotine in the aerosol-generating film may be between 2:1 and 5:1 , between 2:1 and 4.5:1 , between 2:1 and 4:1 , or between 2:1 and 3.5:1.

The aerosol-generating film may have a fumaric acid content of greater than or equal to 0.5 percent by weight, greater than or equal to 1 percent by weight, greater than or equal to 1 .5 percent by weight, or greater than or equal to 2 percent by weight.

The aerosol-generating film may have a fumaric acid content of less than or equal to 8 percent by weight, less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight.

The aerosol-generating film may have a fumaric acid content of between 0.5 percent by weight and 8 percent by weight, between 0.5 percent by weight and 6 percent by weight, or between 0.5 percent by weight and 4 percent by weight.

The aerosol-generating film may have a fumaric acid content of between 1 percent by weight and 8 percent by weight, between 1 percent by weight and 6 percent by weight, or between

1 percent by weight and 4 percent by weight.

The aerosol-generating film may have a fumaric acid content of between 1.5 percent by weight and 8 percent by weight, between 1.5 percent by weight and 6 percent by weight, or between 1.5 percent by weight and 4 percent by weight.

The aerosol-generating film may have a fumaric acid content of between 2 percent by weight and 8 percent by weight, between 2 percent by weight and 6 percent by weight, or between

2 percent by weight and 4 percent by weight.

The molar ratio of fumaric acid to nicotine in the aerosol-generating film may be greater than or equal to 0.5:1 , greater than or equal to 1 :1 , greater than or equal to 1.5:1 , or greater than or equal to 2:1.

The molar ratio of fumaric acid to nicotine in the aerosol-generating film may be less than or equal to 4:1 , or less than or equal to 3.5:1 , less than or equal to 3:1 , or less than or equal to 2.5:1.

The molar ratio of fumaric acid to nicotine in the aerosol-generating film may be between 0.5:1 and 4:1 , between 0.5:1 and 3.5:1 , between 0.5:1 and 3:1 , or between 0.5:1 and 2.5:1. The molar ratio of fumaric acid to nicotine in the aerosol-generating film may be between 1 :1 and 4:1 , between 1 :1 and 3.5:1 , between 1 :1 and 3:1 , or between 1 :1 and 2.5:1.

The molar ratio of fumaric acid to nicotine in the aerosol-generating film may be between 1.5:1 and 4: 1 , between 1.5:1 and 3.5:1 , between 1.5:1 and 3: 1 , or between 1.5:1 and 2.5:1.

The molar ratio of fumaric acid to nicotine in the aerosol-generating film may be between 2:1 and 4:1 , between 2:1 and 3.5:1 , between 2:1 and 3:1 , or between 2:1 and 2.5:1.

The aerosol-generating film comprises one or more cellulose based film-forming agents.

The term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film.

Advantageously, the aerosol-generating film may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose (CMC), ethylcellulose (EC), hydroxyethyl cellulose (HEC), hydroxyethyl methylcellulose (HEMC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), and methylcellulose (MC).

More advantageously, the aerosol-generating film may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose (CMC), ethylcellulose (EC), methylcellulose (MC), and hydroxypropyl methylcellulose (HPMC).

Most advantageously, the aerosol-generating film comprises one or more cellulose based film-forming agents selected from carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC).

Preferably, the aerosol-generating film comprises carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC).

Most preferably, the aerosol-generating film comprises hydroxypropyl methylcellulose (HPMC).

The one or more cellulose based film-forming agents may act as a binding agent for the aerosol-generating film.

The aerosol-generating film may have a total cellulose based film-forming agent content of greater than or equal to 15 percent by weight, greater than or equal to 20 percent by weight, or greater than or equal to 25 percent by weight.

As used herein, the term “total cellulose based film-forming agent content” is used to describe the combined content of all cellulose based film-forming agents in the aerosol-generating film.

The aerosol-generating film may have a total cellulose based film-forming agent content of less than or equal to 40 percent by weight, less than or equal to 35 percent by weight, or less than or equal to 30 percent by weight. The aerosol-generating film may have a total cellulose based film-forming agent content of between 15 percent by weight and 40 percent by weight, between 15 percent by weight and 35 percent by weight, or between 15 percent by weight and 30 percent by weight.

The aerosol-generating film may have a total cellulose based film-forming agent content of between 20 percent by weight and 40 percent by weight, between 20 percent by weight and 35 percent by weight, or between 20 percent by weight and 30 percent by weight.

The aerosol-generating film may have a total cellulose based film-forming agent content of between 25 percent by weight and 40 percent by weight, between 25 percent by weight and 35 percent by weight, or between 25 percent by weight and 30 percent by weight.

Inclusion of hydroxypropylmethyl cellulose in the aerosol-generating film may advantageously facilitate manufacturing of the aerosol-generating film. For example, hydroxypropylmethyl cellulose may advantageously reduce the overall viscosity of a slurry of components of the aerosol-generating film produced during manufacturing of the solid aerosolgenerating substrate. A lower viscosity slurry may flow more easily and be easier to mix, transfer and handle during the manufacturing process

Hydroxypropylmethyl cellulose may advantageously act as a binding agent for the aerosol-generating film.

The aerosol-generating film may have a hydroxypropylmethyl cellulose content of greater than or equal to 14 percent by weight, greater than or equal to 16 percent by weight, greater than or equal to 18 percent by weight, or greater than or equal to 20 percent by weight.

The aerosol-generating film may have a hydroxypropylmethyl cellulose content of less than or equal to 40 percent by weight, less than or equal to 35 percent by weight, less than or equal to 30 percent by weight, or less than or equal to 25 percent by weight.

The aerosol-generating film may have a hydroxypropylmethyl cellulose content of between 14 percent by weight and 40 percent by weight, between 14 percent by weight and 35 percent by weight, between 14 percent by weight and 30 percent by weight, or between 14 percent by weight and 25 percent by weight.

The aerosol-generating film may have a hydroxypropylmethyl cellulose content of between 16 percent by weight and 40 percent by weight, between 16 percent by weight and 35 percent by weight, between 16 percent by weight and 30 percent by weight, or between 16 percent by weight and 25 percent by weight.

The aerosol-generating film may have a hydroxypropylmethyl cellulose content of between 18 percent by weight and 40 percent by weight, between 18 percent by weight and 35 percent by weight, between 18 percent by weight and 30 percent by weight, or between 18 percent by weight and 25 percent by weight. The aerosol-generating film may have a hydroxypropylmethyl cellulose content of between 20 percent by weight and 40 percent by weight, between 20 percent by weight and 35 percent by weight, between 20 percent by weight and 30 percent by weight, or between 20 percent by weight and 25 percent by weight.

Inclusion of carboxymethyl cellulose in the aerosol-generating film may advantageously reduce or eliminate crusting in aerosol-generating articles.

As used herein, the term “crusting” is used to describe the formation of a solid layer on a component of the aerosol-generating article.

Crusting may occur due to a component of the aerosol-generating film melting and then re-solidify around a component of the aerosol-generating article during use thereof. Crusting may be a particular problem in aerosol-generating articles which contain a susceptor in direct contact with the solid aerosol-forming substrate. If a crust is formed on the susceptor, the crusted susceptor may become less effective at heating the aerosol-generating film. This may disadvantageously lead to one or both of reduced delivery of nicotine to a user and reduced formation of aerosol from the aerosol-generating film.

The aerosol-generating film may comprise sodium carboxymethyl cellulose.

The aerosol-generating film may have a carboxymethyl cellulose content of greater than or equal to 2 percent by weight, greater than or equal to 3 percent by weight, greater than or equal to 4 percent by weight, or greater than or equal to 5 percent by weight.

The aerosol-generating film may have a carboxymethyl cellulose content of less than or equal to 12 percent by weight, less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, or less than or equal to 6 percent by weight.

The aerosol-generating film may have a carboxymethyl cellulose content of between 2 percent by weight and 12 percent by weight, between 2 percent by weight and 10 percent by weight, between 2 percent by weight and 8 percent by weight, or between 2 percent by weight and 6 percent by weight.

The aerosol-generating film may have a carboxymethyl cellulose content of between 3 percent by weight and 12 percent by weight, between 3 percent by weight and 10 percent by weight, between 3 percent by weight and 8 percent by weight, or between 3 percent by weight and 6 percent by weight.

The aerosol-generating film may have a carboxymethyl cellulose content of between 4 percent by weight and 12 percent by weight, between 4 percent by weight and 10 percent by weight, between 4 percent by weight and 8 percent by weight, or between 4 percent by weight and 6 percent by weight.

The aerosol-generating film may have a carboxymethyl cellulose content of between 5 percent by weight and 12 percent by weight, between 5 percent by weight and 10 percent by weight, between 5 percent by weight and 8 percent by weight, or between 5 percent by weight and 6 percent by weight.

The term “cellulose based agent” is used to describe a cellulosic substance. Examples of cellulose based agents include the cellulose based film-forming agents described above, as well as cellulose based binding agents and cellulose based strengthening agents.

The aerosol-generating film may comprise a plurality of cellulose based agents, at least one of which is a cellulose-based film-forming agent. That is, the aerosol-generating film may comprise two or more cellulose based agents, at least one of which is a cellulose based filmforming agent. For example, the aerosol-generating film may comprise two cellulose based agents, three cellulose based agents, four cellulose based agents, or five cellulose based agents, at least one of which is a cellulose based film-forming agent.

The aerosol-generating film may have a total cellulose based agent content of greater than or equal to 25 percent by weight, or greater than or equal to 30 percent by weight.

The term “total cellulose based agent content” is used to describe the combined content of all cellulose based agents in the aerosol-generating film. For example, where the aerosolgenerating film comprises a plurality of cellulose based agents consisting of a cellulose based film-forming agent, a cellulose based binding agent, and a cellulose based strengthening agent, the term “total cellulose based agent content” describes the combined cellulose based filmforming agent content, cellulose based strengthening agent content, and cellulose based binding agent content of the aerosol-generating film.

Preferably, the aerosol-generating film has a total cellulose based agent content of greater than or equal to 35 percent by weight.

The aerosol-generating film may have a total cellulose based agent content of greater than or equal to 36 percent by weight, greater than or equal to 38 percent by weight, or greater than or equal to 40 percent by weight.

The aerosol-generating film may have a total cellulose based agent content of less than or equal to 52 percent by weight, less than or equal to 50 percent by weight, less than or equal to 48 percent by weight, less than or equal to 46 percent by weight, or less than or equal to 44 percent by weight.

The aerosol-generating film may have a total cellulose based agent content of between

35 percent by weight and 52 percent by weight, between 35 percent by weight and 50 percent by weight, between 35 percent by weight and 48 percent by weight, between 35 percent by weight and 46 percent by weight, or between 35 percent by weight and 44 percent by weight.

36 percent by weight and 52 percent by weight, between 36 percent by weight and 50 percent by weight, between 36 percent by weight and 48 percent by weight, between 36 percent by weight and 46 percent by weight, or between 36 percent by weight and 44 percent by weight.

The aerosol-generating film may have a total cellulose based agent content of between 38 percent by weight and 52 percent by weight, between 38 percent by weight and 50 percent by weight, between 38 percent by weight and 48 percent by weight, between 38 percent by weight and 46 percent by weight, or between 38 percent by weight and 44 percent by weight.

The aerosol-generating film may have a total cellulose based agent content of between 40 percent by weight and 52 percent by weight, between 40 percent by weight and 50 percent by weight, between 40 percent by weight and 48 percent by weight, between 40 percent by weight and 46 percent by weight, or between 40 percent by weight and 44 percent by weight.

The aerosol-generating film may comprise one or more cellulose based strengthening agents.

Inclusion of one or more cellulose based strengthening agents in the aerosol-generating film may advantageously increase the tensile strength of the aerosol-generating film. An aerosolgenerating film having a higher tensile strength may advantageously be less likely to deteriorate or break during manufacture and storage.

Advantageously, the aerosol-generating film may comprise one or more cellulose based strengthening agents selected from cellulose fibres, cellulose powder, and microcrystalline cellulose (MCC).

Preferably, the aerosol-generating film comprises cellulose fibres. Cellulose fibres may be particularly effective at increasing the tensile strength of the aerosol-generating film.

The aerosol-generating film may have a total cellulose based strengthening agent content of greater than or equal to 5 percent by weight, greater than or equal to 10 percent by weight, or greater than or equal to 15 percent by weight.

The term “total cellulose based strengthening agent content” is used to describe the combined content of all cellulose based strengthening agents in the aerosol-generating film.

The aerosol-generating film may have a total cellulose based strengthening agent content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight.

The aerosol-generating film may have a total cellulose based strengthening agent content of between 5 percent by weight and 30 percent by weight, between 5 percent by weight and 25 percent by weight, or between 5 percent by weight and 20 percent by weight.

The aerosol-generating film may have a total cellulose based strengthening agent content of between 10 percent by weight and 30 percent by weight, between 10 percent by weight and 25 percent by weight, or between 10 percent by weight and 20 percent by weight. The aerosol-generating film may have a total cellulose based strengthening agent content of between 15 percent by weight and 30 percent by weight, between 15 percent by weight and 25 percent by weight, or between 15 percent by weight and 20 percent by weight.

The aerosol-generating film may comprise cellulose fibres having a length of greater than or equal to 0.2 millimetres, greater than or equal to 0.5 millimetres, greater than or equal to 0.7 millimetres, or greater than or equal to 0.9 millimetres.

The aerosol-generating film may comprise cellulose fibres having a length of less than or equal to 2 millimetres, less than or equal to 1.8 millimetres, less than or equal to 1.6 millimetres, or less than or equal to 1 .4 millimetres.

The aerosol-generating film may comprise cellulose fibres having a length of between 0.2 millimetres and 2.0 millimetres, between 0.2 millimetres and 1.8 millimetres, between 0.2 millimetres and 1.6 millimetres, or between 0.2 millimetres and 1.4 millimetres.

The aerosol-generating film may comprise cellulose fibres having a length of between 0.5 millimetres and 2.0 millimetres, between 0.5 millimetres and 1.8 millimetres, between 0.5 millimetres and 1.6 millimetres, or between 0.5 millimetres and 1.4 millimetres.

The aerosol-generating film may comprise cellulose fibres having a length of between 0.7 millimetres and 2.0 millimetres, between 0.7 millimetres and 1.8 millimetres, between 0.7 millimetres and 1.6 millimetres, or between 0.7 millimetres and 1.4 millimetres.

The aerosol-generating film may comprise cellulose fibres having a length of between 0.9 millimetres and 2.0 millimetres, between 0.9 millimetres and 1.8 millimetres, between 0.9 millimetres and 1.6 millimetres, or between 0.9 millimetres and 1.4 millimetres.

The aerosol-generating film may have a cellulose fibre content of greater than or equal to 2 percent by weight, greater than or equal to 5 percent by weight, greater than or equal to 10 percent by weight, or greater than or equal to 15 percent by weight.

The aerosol-generating film may have a cellulose fibre content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight.

The aerosol-generating film may have a cellulose fibre content of between 2 percent by weight and 30 percent by weight, between 2 percent by weight and 25 percent by weight, or between 2 percent by weight and 20 percent by weight.

The aerosol-generating film may have a cellulose fibre content of between 5 percent by weight and 30 percent by weight, between 5 percent by weight and 25 percent by weight, or between 5 percent by weight and 20 percent by weight. The aerosol-generating film may have a cellulose fibre content of between 10 percent by weight and 30 percent by weight, between 10 percent by weight and 25 percent by weight, or between 10 percent by weight and 20 percent by weight.

The aerosol-generating film may have a cellulose fibre content of between 15 percent by weight and 30 percent by weight, between 15 percent by weight and 25 percent by weight, or between 15 percent by weight and 20 percent by weight.

The aerosol-generating film may comprise microcrystalline cellulose having a D50 size of greater than or equal to 5 micrometres, greater than or equal to 10 micrometres, or greater than or equal to 15 micrometres.

As used herein, the term “D50 size” describes the median particle size of a particulate material. The D50 size is the particle size which splits the distribution in half, where half of the particles are larger than the D50 size and half of the particles are smaller than the D50 size. The particle size distribution may be determined by laser diffraction. For example, the particle size distribution may be determined by laser diffraction using a Malvern Mastersizer 3000 laser diffraction particle size analyser in accordance with the manufacturer’s instructions.

The aerosol-generating film may comprise microcrystalline cellulose having a D50 size of less than or equal to 100 micrometres, less than or equal to 90 micrometres, or less than or equal to 80 micrometres.

The aerosol-generating film may comprise microcrystalline cellulose having a D50 size of between 5 micrometres and 100 micrometres, between 5 micrometres and 90 micrometres, or between 5 micrometres and 80 micrometres.

The aerosol-generating film may comprise microcrystalline cellulose having a D50 size of between 10 micrometres and 100 micrometres, between 10 micrometres and 90 micrometres, or between 10 micrometres and 80 micrometres.

The aerosol-generating film may comprise microcrystalline cellulose having a D50 size of between 15 micrometres and 100 micrometres, between 15 micrometres and 90 micrometres, or between 150 micrometres and 80 micrometres.

The aerosol-generating film may have a microcrystalline cellulose content of greater than or equal to 2 percent by weight, greater than or equal to 5 percent by weight, greater than or equal to 10 percent by weight, or greater than or equal to 15 percent by weight.

The aerosol-generating film may have a microcrystalline cellulose content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight.

The aerosol-generating film may have a microcrystalline cellulose content of between 2 percent by weight and 30 percent by weight, between 2 percent by weight and 25 percent by weight, or between 2 percent by weight and 20 percent by weight. The aerosol-generating film may have a microcrystalline cellulose content of between 5 percent by weight and 30 percent by weight, between 5 percent by weight and 25 percent by weight, or between 5 percent by weight and 20 percent by weight.

The aerosol-generating film may have a microcrystalline cellulose content of between 10 percent by weight and 30 percent by weight, between 10 percent by weight and 25 percent by weight, or between 10 percent by weight and 20 percent by weight.

The aerosol-generating film may have a microcrystalline cellulose content of between 15 percent by weight and 30 percent by weight, between 15 percent by weight and 25 percent by weight, or between 15 percent by weight and 20 percent by weight.

The aerosol-generating film may comprise cellulose powder having a D50 size of greater than or equal to 25 micrometres, greater than or equal to 30 micrometres, or greater than or equal to 35 micrometres.

The aerosol-generating film may comprise cellulose powder having a D50 size of less than or equal to 250 micrometres, less than or equal to 225 micrometres, or less than or equal to 200 micrometres.

The aerosol-generating film may comprise cellulose powder having a D50 size of between 25 micrometres and 250 micrometres, between 25 micrometres and 225 micrometres, or between 25 micrometres and 200 micrometres.

The aerosol-generating film may comprise cellulose powder having a D50 size of between 30 micrometres and 250 micrometres, between 30 micrometres and 225 micrometres, or between 30 micrometres and 200 micrometres.

The aerosol-generating film may comprise cellulose powder having a D50 size of between 35 micrometres and 250 micrometres, between 35 micrometres and 225 micrometres, or between 35 micrometres and 200 micrometres.

The aerosol-generating film may have a cellulose powder content of greater than or equal to 2 percent by weight, greater than or equal to 5 percent by weight, greater than or equal to 10 percent by weight, or greater than or equal to 15 percent by weight.

The aerosol-generating film may have a cellulose powder content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight.

The aerosol-generating film may have a cellulose powder content of between 2 percent by weight and 30 percent by weight, between 2 percent by weight and 25 percent by weight, or between 2 percent by weight and 20 percent by weight.

The aerosol-generating film may have a cellulose powder content of between 5 percent by weight and 30 percent by weight, between 5 percent by weight and 25 percent by weight, or between 5 percent by weight and 20 percent by weight. The aerosol-generating film may have a cellulose powder content of between 10 percent by weight and 30 percent by weight, between 10 percent by weight and 25 percent by weight, or between 10 percent by weight and 20 percent by weight.

The aerosol-generating film may have a cellulose powder content of between 15 percent by weight and 30 percent by weight, between 15 percent by weight and 25 percent by weight, or between 15 percent by weight and 20 percent by weight.

The aerosol-generating film may comprise water.

The aerosol-generating film may have a water content of greater than or equal to 5 percent by weight, greater than or equal to 10 percent by weight, greater than or equal to 15 percent by weight, or greater than or equal to 17 percent by weight based on the total weight of the aerosolgenerating film.

The aerosol-generating film may have a water content of less than or equal to 35 percent by weight, less than or equal to 30 percent by weight, or less than or equal to 25 percent by weight based on the total weight of the aerosol-generating film.

The aerosol-generating film may have a water content of between 5 percent by weight and 35 percent by weight, between 5 percent by weight and 30 percent by weight, or between 5 percent by weight and 25 percent by weight based on the total weight of the aerosol-generating film.

The aerosol-generating film may have a water content of between 10 percent by weight and 35 percent by weight, between 10 percent by weight and 30 percent by weight, or between 10 percent by weight and 25 percent by weight based on the total weight of the aerosol-generating film.

The aerosol-generating film may have a water content of between 15 percent by weight and 35 percent by weight, between 15 percent by weight and 30 percent by weight, or between 15 percent by weight and 25 percent by weight based on the total weight of the aerosol-generating film.

The aerosol-generating film may have a water content of between 17 percent by weight and 35 percent by weight, between 17 percent by weight and 30 percent by weight, or between 17 percent by weight and 25 percent by weight based on the total weight of the aerosol-generating film.

The aerosol-generating film may comprise one or more non-cellulose based thickening agents.

As used herein, the term “non-cellulose based thickening agent” is used to describe a non- cellulosic substance that, when added to an aqueous or non-aqueous liquid composition, increases the viscosity of the liquid composition without substantially modifying its other properties. The one or more non-cellulose based thickening agents may increase stability, and improve suspension of components in the liquid composition. A thickening agent may also be referred to as a “thickener” or a “rheology modifier” or “viscosifying agent”.

The aerosol-generating film may comprise one or more non-cellulose based thickening agents selected from alginates, gellan gum, guar gum, gum 71ectio, locust bean gum, pectins, starches, and xanthan gum.

The aerosol-generating film may not comprise iota-carrageenan or kappa-carrageenan. Aerosol-generating films that do not comprise iota-carrageenan or kappa-carrageenan may advantageously remain solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius. This may advantageously reduce or eliminate crusting in aerosolgenerating articles in which a susceptor is in direct contact with the substrate.

The aerosol-generating film may not comprise agar. Aerosol-generating films that do not agar may advantageously remain solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius. This may advantageously reduce or eliminate crusting in aerosol-generating articles in which a susceptor is in direct contact with the substrate.

The aerosol-generating film may have a total non-cellulose based thickening agent content of greater than or equal to 1 percent by weight, greater than or equal to 2 percent by weight, or greater than or equal to 3 percent by weight.

As used herein, the term “total non-cellulose based thickening agent content” is used to describe the combined content of all non-cellulose based thickening agents in the aerosolgenerating film.

The aerosol-generating film may have a total non-cellulose based thickening agent content of less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, or less than or equal to 6 percent by weight.

The aerosol-generating film may have a total non-cellulose based thickening agent content of between 1 percent by weight and 10 percent by weight, between 1 percent by weight and 8 percent by weight, or between 1 percent by weight and 6 percent by weight.

The aerosol-generating film may have a total non-cellulose based thickening agent content of between 2 percent by weight and 10 percent by weight, between 2 percent by weight and 8 percent by weight, or between 2 percent by weight and 6 percent by weight.

The aerosol-generating film may have a total non-cellulose based thickening agent content of between 3 percent by weight and 10 percent by weight, between 3 percent by weight and 8 percent by weight, or between 3 percent by weight and 6 percent by weight.

The aerosol-generating film may comprise one or more flavourants.

Suitable flavourants are known in the art and include, but are not limited to, menthol.

As used herein, the term “menthol” is used to describe the compound 2-isopropyl-5- methylcyclohexanol in any of its isomeric forms. As used herein, the term “total flavourant content” is used to describe the combined content of all flavourants in the aerosol-generating film.

The aerosol-generating film may have a total flavourant content of greater than or equal to 0.5 percent by weight, greater than or equal to 1 percent by weight, greater than or equal to 2 percent by weight, or greater than or equal to 3 percent by weight.

The aerosol-generating film may have a total flavourant content of less than or equal to 6 percent by weight, less than or equal to 5 percent by weight, or less than or equal to 4 percent by weight.

The aerosol-generating film may have a total flavourant content of between 0.5 percent by weight and 6 percent by weight, between 0.5 percent by weight and 5 percent by weight, or between 0.5 percent by weight and 4 percent by weight.

The aerosol-generating film may have a total flavourant content of between 1 percent by weight and 6 percent by weight, between 1 percent by weight and 5 percent by weight, or between

1 percent by weight and 4 percent by weight.

The aerosol-generating film may have a total flavourant content of between 2 percent by weight and 6 percent by weight, between 2 percent by weight and 5 percent by weight, or between

2 percent by weight and 4 percent by weight.

The aerosol-generating film may have a total flavourant content of between 3 percent by weight and 6 percent by weight, between 3 percent by weight and 5 percent by weight, or between

3 percent by weight and 4 percent by weight.

The aerosol-generating film may be a substantially tobacco-free aerosol-generating film.

As used herein, the term “substantially tobacco-free aerosol-generating film” is used to describe a aerosol-generating film having a tobacco content of less than 1 percent by weight. For example, the aerosol-generating film may have a tobacco content of less than 0.75 percent by weight, less than 0.5 percent by weight, or less than 0.25 percent by weight.

The aerosol-generating film may be a tobacco-free aerosol-generating film.

The term “tobacco-free aerosol-generating film” is used to describe a aerosol-generating film having a tobacco content of 0 percent by weight.

In a particularly preferred embodiment, the aerosol-generating film comprises: glycerine in an amount of between 35 percent by weight and 62 percent by weight; carboxymethyl cellulose in an amount of between 2 percent by weight and 12 percent by weight; hydroxypropylmethyl cellulose in an amount of between 14 percent by weight and 40 percent by weight; a total cellulose based strengthening agent content in an amount of between 2 percent by weight and 30 percent by weight; a total carboxylic acid content in an amount of between 0.5 percent by weight and 8 percent by weight; nicotine in an amount of between 0.5 percent by weight and 10 percent by weight; and water in an amount of between 5 percent by weight and 35 percent by weight.

The wrapper circumscribing the rod-shaped aerosol-generating element comprising the aerosol-generating substrate may be a paper wrapper or a non-paper wrapper. Suitable paper wrappers for use in specific embodiments of the invention are known in the art and include, but are not limited to: cigarette papers; and filter plug wraps. Suitable non-paper wrappers for use in specific embodiments of the invention are known in the art and include, but are not limited to sheets of homogenised tobacco materials. In certain preferred embodiments, the wrapper may be formed of a laminate material comprising a plurality of layers. Preferably, the wrapper is formed of an aluminium co-laminated sheet. The use of a co-laminated sheet comprising aluminium advantageously prevents combustion of the aerosol-generating substrate in the event that the aerosol-generating substrate should be ignited, rather than heated in the intended manner.

In certain preferred embodiments of the present invention, an elongate susceptor element is arranged substantially longitudinally within the rod-shaped aerosol-generating element and is in thermal contact with the aerosol-generating substrate.

As used herein with reference to the present invention, the term “susceptor element” refers to a material that can convert electromagnetic energy into heat. When located within a fluctuating electromagnetic field, eddy currents induced in the susceptor element cause heating of the susceptor element. As the elongate susceptor element is located in thermal contact with the aerosol-generating substrate, the aerosol-generating substrate is heated by the susceptor element.

When used for describing the susceptor element, the term “elongate” means that the susceptor element has a length dimension that is greater than its width dimension or its thickness dimension, for example greater than twice its width dimension or its thickness dimension.

The susceptor element is arranged substantially longitudinally within the rod. This means that the length dimension of the elongate susceptor element is arranged to be approximately parallel to the longitudinal direction of the rod, for example within plus or minus 10 degrees of parallel to the longitudinal direction of the rod. In preferred embodiments, the elongate susceptor element may be positioned in a radially central position within the rod, and extends along the longitudinal axis of the rod.

Preferably, the susceptor element extends all the way to a downstream end of the rod of aerosol-generating article. In some embodiments, the susceptor element may extend all the way to an upstream end of the rod of aerosol-generating article. In particularly preferred embodiments, the susceptor element has substantially the same length as the rod-shaped aerosol-generating element, and extends from the upstream end of the rod to the downstream end of the rod.

The susceptor element is preferably in the form of a pin, rod, strip or blade.

The susceptor element preferably has a length from about 5 millimetres to about 15 millimetres, for example from about 6 millimetres to about 12 millimetres, or from about 8 millimetres to about 10 millimetres.

A ratio between the length of the susceptor element and the overall length of the aerosolgenerating article substrate may be from about 0.20 to about 0.35.

Preferably, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article substrate is at least about 0.22, more preferably at least about 0.24, even more preferably at least about 0.26. A ratio between the length of the susceptor element and the overall length of the aerosol-generating article substrate is preferably less than about 0.34, more preferably less than about 0.32, even more preferably less than about 0.30.

In some embodiments, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article substrate is preferably from about 0.22 to about 0.34, more preferably from about 0.24 to about 0.34, even more preferably from about 0.26 to about 0.34. In other embodiments, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article substrate is preferably from about 0.22 to about 0.32, more preferably from about 0.24 to about 0.32, even more preferably from about 0.26 to about 0.32. In further embodiments, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article substrate is preferably from about 0.22 to about 0.30, more preferably from about 0.24 to about 0.3, even more preferably from about 0.26 to about 0.30.

In a particularly preferred embodiment, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article substrate is about 0.27.

The susceptor element preferably has a width from about 1 millimetres to about 5 millimetres.

The susceptor element may generally have a thickness from about 0.01 millimetres to about 2 millimetres, for example from about 0.5 millimetres to about 2 millimetres. In some embodiments, the susceptor element preferably has a thickness from about 10 micrometres to about 500 micrometres, more preferably from about 10 micrometres to about 100 micrometres.

If the susceptor element has a constant cross-section, for example a circular cross-section, it has a preferable width or diameter from about 1 millimetre to about 5 millimetres.

If the susceptor element has the form of a strip or blade, the strip or blade preferably has a rectangular shape having a width of preferably from about 2 millimetres to about 8 millimetres, more preferably from about 3 millimetres to about 5 millimetres. By way of example, a susceptor element in the form of a strip of blade may have a width of about 4 millimetres.

If the susceptor element has the form of a strip or blade, the strip or blade preferably has a rectangular shape and a thickness from about 0.03 millimetres to about 0.15 millimetres, more preferably from about 0.05 millimetres to about 0.09 millimetres. By way of example, a susceptor element in the form of a strip of blade may have a thickness of about 0.07 millimetres.

In a preferred embodiment, the elongate susceptor element is in the form of a strip or blade, preferably has a rectangular shape, and has a thickness from about 55 micrometres to about 65 micrometres.

More preferably, the elongate susceptor element has a thickness from about 57 micrometres to about 63 micrometres. Even more preferably, the elongate susceptor element has a thickness from about 58 micrometres to about 62 micrometres. In a particularly preferred embodiment, the elongate susceptor element has a thickness of about 60 micrometres.

Preferably, the elongate susceptor element has a length which is the same or shorter than the length of the aerosol-generating substrate. Preferably, the elongate susceptor element has a same length as the aerosol-generating substrate.

The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-generating substrate. Preferred susceptor elements comprise a metal or carbon.

A preferred susceptor element may comprise or consist of a ferromagnetic material, for example a ferromagnetic alloy, ferritic iron, or a ferromagnetic steel or stainless steel. A suitable susceptor element may be, or comprise, aluminium. Preferred susceptor elements may be formed from 400 series stainless steels, for example grade 410, or grade 420, or grade 430 stainless steel. Different materials will dissipate different amounts of energy when positioned within electromagnetic fields having similar values of frequency and field strength.

Thus, parameters of the susceptor element such as material type, length, width, and thickness may all be altered to provide a desired power dissipation within a known electromagnetic field. Preferred susceptor elements may be heated to a temperature in excess of 250 degrees Celsius.

Suitable susceptor elements may comprise a non-metallic core with a metal layer disposed on the non-metallic core, for example metallic tracks formed on a surface of a ceramic core. A susceptor element may have a protective external layer, for example a protective ceramic layer or protective glass layer encapsulating the susceptor element. The susceptor element may comprise a protective coating formed by a glass, a ceramic, or an inert metal, formed over a core of susceptor element material. The susceptor element is arranged in thermal contact with the aerosol-generating substrate. Thus, when the susceptor element heats up the aerosol-generating substrate is heated up and an aerosol is formed. Preferably the susceptor element is arranged in direct physical contact with the aerosol-generating substrate, for example within the aerosol-generating substrate.

The susceptor element may be a multi-material susceptor element and may comprise a first susceptor element material and a second susceptor element material. The first susceptor element material is disposed in intimate physical contact with the second susceptor element material. The second susceptor element material preferably has a Curie temperature that is lower than 500 degrees Celsius. The first susceptor element material is preferably used primarily to heat the susceptor element when the susceptor element is placed in a fluctuating electromagnetic field. Any suitable material may be used. For example the first susceptor element material may be aluminium, or may be a ferrous material such as a stainless steel. The second susceptor element material is preferably used primarily to indicate when the susceptor element has reached a specific temperature, that temperature being the Curie temperature of the second susceptor element material. The Curie temperature of the second susceptor element material can be used to regulate the temperature of the entire susceptor element during operation. Thus, the Curie temperature of the second susceptor element material should be below the ignition point of the aerosol-generating substrate. Suitable materials for the second susceptor element material may include nickel and certain nickel alloys.

By providing a susceptor element having at least a first and a second susceptor element material, with either the second susceptor element material having a Curie temperature and the first susceptor element material not having a Curie temperature, or first and second susceptor element materials having first and second Curie temperatures distinct from one another, the heating of the aerosol-generating substrate and the temperature control of the heating may be separated. The first susceptor element material is preferably a magnetic material having a Curie temperature that is above 500 degrees Celsius. It is desirable from the point of view of heating efficiency that the Curie temperature of the first susceptor element material is above any maximum temperature that the susceptor element should be capable of being heated to. The second Curie temperature may preferably be selected to be lower than 400 degrees Celsius, preferably lower than 380 degrees Celsius, or lower than 360 degrees Celsius. It is preferable that the second susceptor element material is a magnetic material selected to have a second Curie temperature that is substantially the same as a desired maximum heating temperature. That is, it is preferable that the second Curie temperature is approximately the same as the temperature that the susceptor element should be heated to in order to generate an aerosol from the aerosol-generating substrate. The second Curie temperature may, for example, be within the range of 200 degrees Celsius to 400 degrees Celsius, or between 250 degrees Celsius and 360 degrees Celsius. The second Curie temperature of the second susceptor element material may, for example, be selected such that, upon being heated by a susceptor element that is at a temperature equal to the second Curie temperature, an overall average temperature of the aerosol-generating substrate does not exceed 240 degrees Celsius.

The aerosol-generating articles of the present invention may further comprise an upstream element located upstream of and adjacent to the aerosol-generating substrate, wherein the upstream section comprises at least one upstream element. The upstream element advantageously prevents direct physical contact with the upstream end of the aerosol-generating substrate. In particular, where the aerosol-generating substrate comprises a susceptor element, the upstream element may prevent direct physical contact with the upstream end of the susceptor element. This helps to prevent the displacement or deformation of the susceptor element during handling or transport of the aerosol-generating article. This in turn helps to secure the form and position of the susceptor element. Furthermore, the presence of an upstream element helps to prevent any loss of the substrate, which may be advantageous, for example, if the substrate contains particulate plant material.

The upstream element may also provide an improved appearance to the upstream end of the aerosol-generating article. Furthermore, if desired, the upstream element may be used to provide information on the aerosol-generating article, such as information on brand, flavour, content, or details of the aerosol-generating device that the article is intended to be used with.

The upstream element may be a porous plug element. Preferably, a porous plug element does not alter the resistance to draw of the aerosol-generating article. Preferably, the upstream element has a porosity of at least about 50 percent in the longitudinal direction of the aerosolgenerating article. More preferably, the upstream element has a porosity of between about 50 percent and about 90 percent in the longitudinal direction. The porosity of the upstream element in the longitudinal direction is defined by the ratio of the cross-sectional area of material forming the upstream element and the internal cross-sectional area of the aerosol-generating article at the position of the upstream element.

The upstream element may be made of a porous material or may comprise a plurality of openings. This may, for example, be achieved through laser perforation. Preferably, the plurality of openings is distributed homogeneously over the cross-section of the upstream element.

The porosity or permeability of the upstream element may advantageously be varied in order to provide a desirable overall resistance to draw of the aerosol-generating article.

Preferably, the RTD of the upstream element is at least about 5 millimetres H2O. More preferably, the RTD of the upstream element is at least about 10 millimetres H2O. Even more preferably, the RTD of the upstream element is at least about 15 millimetres H2O. In particularly preferred embodiments, the RTD of the upstream element is at least about 20 millimetres H2O. The RTD of the upstream element is preferably less than or equal to about 80 millimetres H2O. More preferably, the RTD of the upstream element is less than or equal to about 60 millimetres H2O. Even more preferably, the RTD of the upstream element is less than or equal to about 40 millimetres H2O.

In some embodiments, the RTD of the upstream element is from about 5 millimetres H2O to about 80 millimetres H2O, preferably from about 10 millimetres H2O to about 80 millimetres H2O, more preferably from about 15 millimetres H2O to about 80 millimetres H2O, even more preferably from about 20 millimetres H2O to about 80 millimetres H2O. In other embodiments, the RTD of the upstream element is from about 5 millimetres H2O to about 70 millimetres H2O, preferably from about 10 millimetres H2O to about 70 millimetres H2O, more preferably from about 15 millimetres H2O to about 70 millimetres H2O, even more preferably from about 20 millimetres H2O to about 70 millimetres H₂O.ln other embodiments, the RTD of the upstream element is from about 5 millimetres H2O to about 60 millimetres H2O, preferably from about 10 millimetres H2O to about 60 millimetres H2O, more preferably from about 15 millimetres H2O to about 60 millimetres H2O, even more preferably from about 20 millimetres H2O to about 60 millimetres H2O. In further embodiments, the RTD of the upstream element is from about 5 millimetres H2O to about 40 millimetres H2O, preferably from about 10 millimetres H2O to about 40 millimetres H2O, more preferably from about 15 millimetres H2O to about 40 millimetres H2O, even more preferably from about 20 millimetres H2O to about 40 millimetres H2O.

In alternative embodiments, the upstream element may be formed from a material that is impermeable to air. In such embodiments, the aerosol-generating article may be configured such that air flows into the rod-shaped aerosol-generating element through suitable ventilation means provided in a wrapper.

The upstream element may be made of any material suitable for use in an aerosolgenerating article. The upstream element may, for example, be made of a same material as used for one of the other components of the aerosol-generating article, such as the mouthpiece, the cooling element or the support element. Suitable materials for forming the upstream element include filter materials, ceramic, polymer material, cellulose acetate, cardboard, zeolite or aerosolgenerating substrate. Preferably, the upstream element is formed from a plug of cellulose acetate.

Preferably, the upstream element is formed of a heat resistant material. For example, preferably the upstream element is formed of a material that resists temperatures of up to 350 degrees Celsius. This ensures that the upstream element is not adversely affected by the heating means for heating the aerosol-generating substrate.

Preferably, the upstream element has a diameter that is approximately equal to the diameter of the aerosol-generating article. Preferably, the upstream element has a length of between about 1 millimetre and about 10 millimetres, more preferably between about 3 millimetres and about 8 millimetres, more preferably between about 4 millimetres and about 6 millimetres. In a particularly preferred embodiment, the upstream element has a length of about 5 millimetres. The length of the upstream element can advantageously be varied in order to provide the desired total length of the aerosol-generating article. For example, where it is desired to reduce the length of one of the other components of the aerosol-generating article, the length of the upstream element may be increased in order to maintain the same overall length of the article.

The upstream element preferably has a substantially homogeneous structure. For example, the upstream element may be substantially homogeneous in texture and appearance. The upstream element may, for example, have a continuous, regular surface over its entire cross section. The upstream element may, for example, have no recognisable symmetries.

The upstream element is preferably circumscribed by a wrapper. The wrapper circumscribing the upstream element is preferably a stiff plug wrap, for example, a plug wrap having a basis weight of at least about 80 grams per square metre (gsm), or at least about 100 gsm, or at least about 110 gsm. This provides structural rigidity to the upstream element.

The aerosol-generating article according to the present invention may have a length from about 35 millimetres to about 100 millimetres.

Preferably, an overall length of an aerosol-generating article in accordance with the invention is at least about 38 millimetres. More preferably, an overall length of an aerosolgenerating article in accordance with the invention is at least about 40 millimetres. Even more preferably, an overall length of an aerosol-generating article in accordance with the invention is at least about 42 millimetres.

An overall length of an aerosol-generating article in accordance with the invention is preferably less than or equal to 70 millimetres. More preferably, an overall length of an aerosolgenerating article in accordance with the invention is preferably less than or equal to 60 millimetres. Even more preferably, an overall length of an aerosol-generating article in accordance with the invention is preferably less than or equal to 50 millimetres.

In some embodiments, an overall length of the aerosol-generating article is preferably from about 38 millimetres to about 70 millimetres, more preferably from about 40 millimetres to about 70 millimetres, even more preferably from about 42 millimetres to about 70 millimetres. In other embodiments, an overall length of the aerosol-generating article is preferably from about 38 millimetres to about 60 millimetres, more preferably from about 40 millimetres to about 60 millimetres, even more preferably from about 42 millimetres to about 60 millimetres. In further embodiments, an overall length of the aerosol-generating article is preferably from about 38 millimetres to about 50 millimetres, more preferably from about 40 millimetres to about 50 millimetres, even more preferably from about 42 millimetres to about 50 millimetres. In an exemplary embodiment, an overall length of the aerosol-generating article is about 45 millimetres.

The aerosol-generating article preferably has an external diameter of at least 5 millimetres. Preferably, the aerosol-generating article has an external diameter of at least 6 millimetres. More preferably, the aerosol-generating article has an external diameter of at least 7 millimetres.

Preferably, the aerosol-generating article has an external diameter of less than or equal to about 12 millimetres. More preferably, the aerosol-generating article has an external diameter of less than or equal to about 10 millimetres. Even more preferably, the aerosol-generating article has an external diameter of less than or equal to about 8 millimetres.

In some embodiments, the aerosol-generating article has an external diameter from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In other embodiments, the aerosol-generating article has an external diameter from about 5 millimetres to about 10 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres. In further embodiments, the aerosol-generating article has an external diameter from about 5 millimetres to about 8 millimetres, preferably from about 6 millimetres to about 8 millimetres, more preferably from about 7 millimetres to about 8 millimetres.

In certain preferred embodiments of the invention, a diameter (DME) of the aerosolgenerating article at the mouth end is (preferably) greater than a diameter (DDE) of the aerosolgenerating article at the distal end. In more detail, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is (preferably) at least about 1.005.

Preferably, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is (preferably) at least about 1.01. More preferably, a ratio (DME/DDE) between the diameter of the aerosolgenerating article at the mouth end and the diameter of the aerosol-generating article at the distal end is at least about 1 .02. Even more preferably, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is at least about 1.05.

A ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is preferably less than or equal to about 1 .30. More preferably, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is less than or equal to about 1 .25. Even more preferably, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is less than or equal to about 1.20. In particularly preferred embodiments, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is less than or equal to 1.15 or 1.10.

In some preferred embodiments, a ratio (DME/DDE) between the diameter of the aerosolgenerating article at the mouth end and the diameter of the aerosol-generating article at the distal end is from about 1 .01 to 1 .30, more preferably from 1.02 to 1.30, even more preferably from 1 .05 to 1.30.

In other embodiments, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is from about 1.01 to 1.25, more preferably from 1.02 to 1.25, even more preferably from 1.05 to 1.25. In further embodiments, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is from about 1.01 to 1.20, more preferably from 1.02 to 1.20, even more preferably from 1.05 to 1.20. In yet further embodiments, a ratio (DME/DDE) between the diameter of the aerosol-generating article at the mouth end and the diameter of the aerosol-generating article at the distal end is from about 1.01 to 1.15, more preferably from 1.02 to 1.15, even more preferably from 1.05 to 1.15.

By way of example, the external diameter of the article may be substantially constant over a distal portion of the article extending from the distal end of the aerosol-generating article for at least about 5 millimetres or at least about 10 millimetres. As an alternative, the external diameter of the article may taper over a distal portion of the article extending from the distal end for at least about 5 millimetres or at least about 10 millimetres.

In certain preferred embodiments of the present invention, the elements of the aerosolgenerating article, as described above, are arranged such that the centre of mass of the aerosolgenerating article is at least about 60 percent of the way along the length of the aerosol-generating article from the downstream end. More preferably, the elements of the aerosol-generating article are arranged such that the centre of mass of the aerosol-generating article is at least about 62 percent of the way along the length of the aerosol-generating article from the downstream end, more preferably at least about 65 percent of the way along the length of the aerosol-generating article from the downstream end.

Preferably, the centre of mass is no more than about 70 percent of the way along the length of the aerosol-generating article from the downstream end.

Providing an arrangement of elements that gives a centre of mass that is closer to the upstream end than the downstream end results in an aerosol-generating article having a weight imbalance, with a heavier upstream end. This weight imbalance may advantageously provide haptic feedback to the consumer to enable them to distinguish between the upstream and downstream ends so that the correct end can be inserted into an aerosol-generating device. This may be particularly beneficial where an upstream element is provided such that the upstream and downstream ends of the aerosol-generating article are visually similar to each other.

In embodiments of aerosol-generating articles in accordance with the invention, wherein both aerosol-cooling element and support element are present, these are preferably wrapped together in a combined wrapper. The combined wrapper circumscribes the aerosol-cooling element and the support element, but does not circumscribe elements further downstream, such as a mouthpiece filter segment.

In these embodiments, the aerosol-cooling element and the support element are combined prior to being circumscribed by the combined wrapper, before they are further combined with the mouthpiece segment.

From a manufacturing viewpoint, this is advantageous in that it enables shorter aerosolgenerating articles to be assembled.

In general, it may be difficult to handle individual elements that have a length smaller than their diameter. For example, for elements with a diameter of 7 millimetres, a length of about 7 millimetres represents a threshold value close to which it is preferable not to go. However, an aerosol-cooling element of 10 millimetres can be combined with a pair of support elements of 7 millimetres on each side (and potentially with other elements like the rod-shaped aerosolgenerating element, etc.) to provide a hollow segment of 24 millimetres, which is subsequently cut into two intermediate hollow sections of 12 millimetres.

In particularly preferred embodiments, the other components of the aerosol-generating article are individually circumscribed by their own wrapper. In other words, the upstream element, the rod-shaped aerosol-generating element, the support element, and the aerosol-cooling element are all individually wrapped. The support element and the aerosol-cooling element are combined to form the hollow section. This is achieved by wrapping the support element and the aerosol-cooling element by means of a combined wrapper. The upstream element, the rodshaped aerosol-generating element, and the hollow section are then combined together with an outer wrapper. Subsequently, they are combined with the mouthpiece section- which has a wrapper of its own - by means of tipping paper.

Preferably, at least one of the components of the aerosol-generating article is wrapped in a hydrophobic wrapper.

The term “hydrophobic” refers to a surface exhibiting water repelling properties. One useful way to determine this is to measure the water contact angle. The “water contact angle” is the angle, conventionally measured through the liquid, where a liquid/vapour interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via the Young equation. Hydrophobicity or water contact angle may be determined by utilizing TAPPI T558 test method and the result is presented as an interfacial contact angle and reported in “degrees” and can range from near zero to near 180 degrees.

In preferred embodiments, the hydrophobic wrapper is one including a paper layer having a water contact angle of about 30 degrees or greater, and preferably about 35 degrees or greater, or about 40 degrees or greater, or about 45 degrees or greater.

By way of example, the paper layer may comprise PVOH (polyvinyl alcohol) or silicon. The PVOH may be applied to the paper layer as a surface coating, or the the paper layer may comprise a surface treatment comprising PVOH or silicon.

In a particularly preferred embodiment, an aerosol-generating article in accordance with the present invention comprises, in linear sequential arrangement, an upstream element, a rodshaped aerosol-generating element located immediately downstream of the upstream element, a support element located immediately downstream of the rod-shaped aerosol-generating element, an aerosol-cooling element located immediately downstream of the support element, a mouthpiece section comprising a single mouthpiece filter segment located immediately downstream of the aerosol-cooling element, and an outer wrapper circumscribing the upstream element, the rod of aerosol-generating substrate, the support element, the aerosol-cooling element and the mouthpiece filter segment.

In more detail, the rod-shaped aerosol-generating element may abut the upstream element. The support element may abut the rod-shaped aerosol-generating element. The aerosol-cooling element may abut the support element. The mouthpiece filter segment may abut the aerosolcooling element.

The aerosol-generating article has a substantially cylindrical shape and an outer diameter of about 7.25 millimetres.

The upstream element has a length of about 5 millimetres, the rod of aerosol-generating article has a length of about 12 millimetres, the support element has a length of about 8 millimetres, the aerosol-cooling element has a length of about 8 millimetres and the mouthpiece filter segment has a length of about 12 millimetres. Thus, an overall length of the aerosolgenerating article is about 45 millimetres.

The upstream element is in the form of a plug of cellulose acetate wrapped in stiff plug wrap.

The aerosol-generating article comprises an elongate susceptor element arranged substantially longitudinally within the rod-shaped aerosol-generating element and is in thermal contact with the aerosol-generating substrate. The susceptor element is in the form of a strip or blade, has a length substantially equal to the length of the rod-shaped aerosol-generating element and a thickness of about 60 micrometres. The support element is in the form of a hollow cellulose acetate tube and has an internal diameter of about 1.9 millimetres. Thus, a thickness of a peripheral wall of the support element is about 2.675 millimetres.

The aerosol-cooling element is in the form of a finer hollow cellulose acetate tube and has an internal diameter of about 3.25 millimetres. Thus, a thickness of a peripheral wall of the aerosol-cooling element is about 2 millimetres.

The mouthpiece is in the form of a low-density cellulose acetate filter segment.

The rod-shaped aerosol-generating element comprises the aerosol-generating substrate comprising an aerosol-generating film described above.

In the following, the invention will be further described with reference to the drawing of the accompanying figures.

Figure 1 shows a schematic side sectional view of an aerosol-generating article in accordance with an embodiment of the invention;

Figure 2 shows a schematic side sectional view of another aerosol-generating article in accordance with another embodiment of the invention;

Figure 3 shows a schematic side sectional view of another aerosol-generating article in accordance with another embodiment of the invention.

Figure 4 shows a schematic side sectional view of another aerosol-generating article in accordance with another embodiment of the invention.

Figure 5 shows a schematic side sectional view of another aerosol-generating article in accordance with another embodiment of the invention.

The aerosol-generating article 10 shown in Figure 1 comprises a rod 12 of aerosolgenerating substrate 12 and a downstream section 14 at a location downstream of the rod 12 of aerosol-generating substrate. Thus, the aerosol-generating article 10 extends from an upstream or distal end 16 - which substantially coincides with an upstream end of the rod 12 - to a downstream or mouth end 18, which coincides with a downstream end of the downstream section 14.

The aerosol-generating article 10 has an overall length of about 45 millimetres.

The rod of aerosol-generating substrate 12 comprises an aerosol-generating film as described herein.

The downstream section 14 comprises a hollow tubular element 20 located immediately downstream of the rod 12 of aerosol-generating substrate, the hollow tubular element 20 being in longitudinal alignment with the rod 12. In the embodiment of Figure 1 , the upstream end of the hollow tubular element 20 abuts the downstream end of the rod 12 of aerosol-generating substrate. The hollow tubular element 20 defines a hollow section 15 of the aerosol-generating article 10. The hollow tubular element does not substantially contribute to the overall RTD of the aerosolgenerating article. In more detail, an RTD of the downstream section is about 0 mm H2O.

The hollow tubular element 20 is provided in the form of a hollow cylindrical tube made of cellulose acetate or of stiff paper, such as paper having a grammage of at least about 90 g/sqm. The hollow tubular element 20 defines an internal cavity 22 that extends all the way from an upstream end 24 of the hollow tubular element to a downstream end 26 of the hollow tubular element 20. The internal cavity 22 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 22. The hollow tubular element 20 does not substantially contribute to the overall RTD of the aerosol-generating article 10.

The hollow tubular element 20 has a length of about 33 millimetres, an external diameter (DE) of about 7.3 millimetres, and an internal diameter (Di) of about 7.1 millimetres. Thus, a thickness of a peripheral wall of the hollow tubular element 20 is about 0.1 millimetres.

The aerosol-generating article 10 comprises a ventilation zone 30 provided at a location along the hollow tubular element 20. In more detail, the ventilation zone 30 is provided at about 18 millimetres from the downstream end 26 of the hollow tubular element 20. As such, in the embodiment of Figure 1 the ventilation zone 30 is effectively provided at 18 millimetres from the mouth end 18 of the aerosol-generating article 10. A ventilation level of the aerosol-generating article 10 is about 40 percent.

In the embodiment of Figure 1 , the aerosol-generating article does not comprise any additional component upstream of the rod of aerosol-generating substrate 12 or downstream of the hollow tubular element 20.

The aerosol-generating article 100 shown in Figure 2 differs from the aerosol-generating article 10 described above only by the provision of an upstream section 40 at a location upstream of the aerosol-generating element. Accordingly, the aerosol-generating article 100 will only be described insofar as it differs from the aerosol-generating article 10.

On top of a rod 12 of aerosol-generating substrate and a downstream section 14 at a location downstream of the rod 12, the aerosol-generating article 100 comprises an upstream section 40 at a location upstream of the rod 12. As such, the aerosol-generating article 10 extends from a distal end 16 substantially coinciding with an upstream end of the upstream section 40 to a mouth end or downstream end 18 substantially coinciding with a downstream end of the downstream section 14.

The upstream section 40 comprises an upstream element 42 located immediately upstream of the rod 12 of aerosol-generating substrate, the upstream element 42 being in longitudinal alignment with the rod 12. In the embodiment of Figure 2, the downstream end of the upstream element 42 abuts the upstream end of the rod 12 of aerosol-generating substrate. The upstream element 42 is provided in the form of a cylindrical plug of cellulose acetate circumscribed by a stiff wrapper. The upstream element 42 has a length of about 5 millimetres. The RTD of the upstream element 42 is about 30 millimetres H2O.

The aerosol-generating article 110 shown in Figure 3 comprises a rod 12 of aerosolgenerating substrate and a downstream section 14 at a location downstream of the rod 12 of aerosol-generating substrate. Further, the aerosol-generating article 110 comprises an upstream section 40 at a location upstream of the rod 12 of aerosol-generating substrate. Thus, the aerosolgenerating article 110 extends from an upstream or distal end 16 to a downstream or mouth end 18.

The aerosol-generating article has an overall length of about 45 millimetres.

The downstream section 14 comprises a support element 46 located immediately downstream of the rod 12 of aerosol-generating substrate, the support element 46 being in longitudinal alignment with the rod 12. In the embodiment of Figure 3, the upstream end 48 of the support element 46 abuts the downstream end of the rod 12 of aerosol-generating substrate. In addition, the downstream section 14 comprises an aerosol-cooling element 50 located immediately downstream of the support element 46, the aerosol-cooling element 50 being in longitudinal alignment with the rod 12 and the support element 46. In the embodiment of Figure 4, the upstream end 52 of the aerosol-cooling element 50 abuts the downstream end 54 of the support element 46.

As will become apparent from the following description, the support element 46 and the aerosol-cooling element 50 together define an intermediate hollow section 15 of the aerosolgenerating article 110. As a whole, the intermediate hollow section 15 does not substantially contribute to the overall RTD of the aerosol-generating article. An RTD of the intermediate hollow section 15 as a whole is substantially 0 millimetres H2O.

The support element 46 comprises a first hollow tubular element 56. The first hollow tubular element 56 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The first hollow tubular element 56 defines an internal cavity 58 that extends all the way from an upstream end 48 of the first hollow tubular element to an downstream end 54 of the first hollow tubular element 56. The internal cavity 58 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 58. The first hollow tubular element 56 - and, as a consequence, the support element 46 - does not substantially contribute to the overall RTD of the aerosol-generating article 110. In more detail, the RTD of the first hollow tubular element 56 (which is essentially the RTD of the support element 46) is substantially 0 millimetres H2O.

The first hollow tubular element 56 has a length of about 8 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter (DFTS) of about 1.9 millimetres. Thus, a thickness of a peripheral wall of the first hollow tubular element 56 is about 2.67 millimetres. The aerosol-cooling element 50 comprises a second hollow tubular element 60. The second hollow tubular element 60 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The second hollow tubular element 60 defines an internal cavity 62 that extends all the way from an upstream end 52 of the second hollow tubular element to a downstream end 64 of the second hollow tubular element 60. The internal cavity 62 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 62. The second hollow tubular element 60 - and, as a consequence, the aerosol-cooling element 50 - does not substantially contribute to the overall RTD of the aerosol-generating article 110. In more detail, the RTD of the second hollow tubular element 60 (which is essentially the RTD of the aerosol-cooling element 124) is substantially 0 millimetres H2O.

The second hollow tubular element 60 has a length of about 8 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter (DSTS) of about 3.25 millimetres. Thus, a thickness of a peripheral wall of the second hollow tubular element 60 is about 2 millimetres. Thus, a ratio between the internal diameter (DFTS) of the first hollow tubular element 56 and the internal diameter (DSTS) of the second hollow tubular element 60 is about 0.75.

The aerosol-generating article 110 comprises a ventilation zone 30 provided at a location along the second hollow tubular element 60. In more detail, the ventilation zone is provided at about 2 millimetres from the upstream end of the second hollow tubular element 60. A ventilation level of the aerosol-generating article 110 is about 25 percent.

In the embodiment of Figure 3, the downstream section 14 further comprises a mouthpiece section 68 at a location downstream of the intermediate hollow section 15. The mouthpiece section 68 is provided in the form of a single mouthpiece filter segment 66, a cylindrical plug of low-density cellulose acetate. In more detail, the mouthpiece filter segment 66 is positioned immediately downstream of the aerosol-cooling element 50. As shown in the drawing of Figure 3, an upstream end of the mouthpiece filter segment 66 abuts the downstream end 64 of the aerosol-cooling element 50. The mouthpiece filter segment 66 extends all the way to the mouth end 18 of the aerosol-generating article 110.

The mouthpiece section 68 and mouthpiece filter segment 66 both have a length of about 12 millimetres and an external diameter of about 7.25 millimetres. The RTD of the mouthpiece section 68 (and mouthpiece filter segment 66) is about 12 millimetres H2O. The ratio of the length of the mouthpiece section 68 to the length of the intermediate hollow section 15 is approximately 0.75. The ratio of the length of mouthpiece filter segment 66 to the length of the intermediate hollow section 15 is approximately 0.75.

The rod 12 comprises an aerosol-generating substrate of one of the types described above.

The rod 12 of aerosol-generating substrate has an external diameter of about 7.25 millimetres and a length of about 12 millimetres. The aerosol-generating article 110 further comprises an elongate susceptor element 44 within the rod 12 of aerosol-generating substrate. In more detail, the susceptor element 44 is arranged substantially longitudinally within the aerosol-generating substrate, such as to be approximately parallel to the longitudinal direction of the rod 12. As shown in the drawing of Figure 3, the susceptor element 44 is positioned in a radially central position within the rod and extends effectively along the longitudinal axis of the rod 12.

The susceptor element 44 extends all the way from an upstream end to a downstream end of the rod 12. In effect, the susceptor element 44 has substantially the same length as the rod 12 of aerosol-generating substrate.

In the embodiment of Figure 3, the susceptor element 44 is provided in the form of a strip and has a length of about 12 millimetres, a thickness of about 60 micrometres, and a width of about 4 millimetres. The upstream section 40 comprises an upstream element 42 located immediately upstream of the rod 12 of aerosol-generating substrate, the upstream element 42 being in longitudinal alignment with the rod 12. In the embodiment of Figure 3, the downstream end of the upstream element 42 abuts the upstream end of the rod 12 of aerosol-generating substrate. This advantageously prevents the susceptor element 44 from being dislodged. Further, this ensures that the consumer cannot accidentally contact the heated susceptor element 44 after use.

The upstream element 42 is provided in the form of a cylindrical plug of cellulose acetate circumscribed by a stiff wrapper. The upstream element 42 has a length of about 5 millimetres. The RTD of the upstream element 42 is about 30 millimetres H2O.

The aerosol-generating article 120 shown in Figure 4 differs from the aerosol-generating article 110 described above only by the provision of a mouth end cavity 70 in the mouthpiece section 68. The upstream end 74 of a third hollow tubular element 72 abuts mouthpiece filter segment 66 at the downstream end of mouthpiece filter segment 66. The third hollow tubular element 72 defines a mouth end cavity 70 at the mouth end 18 of the aerosol-generating article 120.

The third hollow tubular element 72 has a length of about 7 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter (DSTS) of about 3.25 millimetres. Thus, a thickness of a peripheral wall of the second hollow tubular element 72 is about 2 millimetres.

The mouthpiece section 68 has a length of about 12 millimetres and an external diameter of about 7.25 millimetres. The RTD of the mouthpiece section 68 is about 5 millimetres H2O. The ratio of the length of the mouthpiece section 68 to the length of the intermediate hollow section 15 is 0.75.

Aerosol-generating article 130 in Figure 5 is otherwise identical to aerosol-generating article

110 of Figure 3, with the exception that in downstream section 14, the mouthpiece section 68 is replaced with third hollow tubular element 72. As with aerosol-generating articles 10 and 110 in Figures 1 and 2, the hollow section 15 extends from the downstream end of the aerosolgenerating substrate 12 all the way to the mouth end 18 of the aerosol-generating article 130. In the aerosol-generating article 130 of Figure 5, in the downstream section 14, the third hollow tubular element 72 abuts the second hollow tubular element 50 at the downstream end 64 of the second hollow tubular element 50. The third hollow tubular element 72 provides a mouth end cavity 70 at the mouth end 18 of the aerosol-generating article 130. The third hollow tubular element 72 provides a second aerosol-cooling element 76, immediately downstream of the first aerosol-cooling element 60. The third hollow tubular element 72 has a length of about 12 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter (DSTS) of about 3.25 millimetres. Thus, a thickness of a peripheral wall of the third hollow tubular element 72 is about 2 millimetres.

Claims

1. An aerosol-generating article for producing an inhalable aerosol upon heating, the aerosol-generating article extending from a mouth end to a distal end and comprising: a rod-shaped aerosol-generating element comprising an aerosol-generating substrate, the aerosol-generating substrate comprising an aerosol-generating film; a downstream section at a location downstream of the aerosol-generating element, the downstream section extending from a downstream end of the aerosol-generating element to the mouth end of the aerosol-generating article; wherein the downstream section comprises a hollow section defining a longitudinal cavity providing an unrestricted flow channel; wherein an RTD of the downstream section is less than 25 mm H2O; wherein the aerosol-generating film comprises one or more cellulose based film-forming agents and one or more aerosol formers, and wherein the aerosol-generating film has a total aerosol former content of greater than or equal to 46 percent by weight.

2. An aerosol-generating article according to claim 1 , wherein the hollow section comprises a first hollow tubular element defining the longitudinal cavity providing the unrestricted flow channel.

3. An aerosol-generating article according to claim 2, wherein the hollow section further comprises a second hollow tubular element, the first and second hollow tubular elements defining the longitudinal cavity providing the unrestricted flow channel.

4. An aerosol-generating article according to any one of claims 1 to 3, wherein the hollow section has a length of at least about 25 millimetres and extends all the way to the mouth end of the aerosol-generating article.

5. An aerosol-generating article according to any one of claims 1 to 4, wherein the downstream section further comprises a mouthpiece section comprising at least one mouthpiece filter segment formed of a fibrous filtration material.

6. An aerosol-generating article according to any one of claims 1 to 5, wherein the RTD of the downstream section is less than about 20 mm H2O, preferably less than about 15 mm H2O, preferably less than about 10 mm H2O, preferably less than about 5 mm H2O, preferably about 0 mm H2O.

7. An aerosol-generating article according to any one of claims 1 to 6, wherein the aerosolgenerating film comprises one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, undecanoic acid and C1-C10 saturated alkyl mono-carboxylic acids.

8. An aerosol-generating article according to any one of claims 1 to 7, wherein the aerosolgenerating film comprises fumaric acid.

9. An aerosol-generating article according to any one of claims 1 to 8, wherein the aerosolgenerating film further comprises one or more carboxylic acids selected from lactic acid and levulinic acid.

10. An aerosol-generating article according to any one of claims 1 to 9, wherein the aerosolgenerating film has a total carboxylic acid content of between 1 percent and 6 percent by weight.

11. An aerosol-generating article according to any one of claims 1 to 10, wherein the one or more aerosol formers comprise glycerine.

12. An aerosol-generating article according to any one of claims 1 to 11 , wherein the one or more cellulose based film-forming agents are selected from carboxymethyl cellulose and hydroxypropylmethyl cellulose.

13. An aerosol-generating article according to any one of claims 1 to 12, wherein the aerosolgenerating film has a hydroxypropylmethyl cellulose content of between 14 percent by weight and 40 percent by weight.

14. An aerosol-generating article according to any one of claims 1 to 13, wherein the aerosolgenerating film comprises one or more cellulose based strengthening agents selected from cellulose fibres, microcrystalline cellulose and cellulose powder.

15. An aerosol-generating article according to any one of claims 1 to 14, wherein the aerosolgenerating film has a total aerosol former content of between 46 percent by weight and 62 percent by weight.