CN118317703A - Aerosol-generating article comprising a hollow tubular matrix element - Google Patents

Abstract

An aerosol generating article (10)(110) comprises: an aerosol generating substrate (12), the aerosol generating substrate comprising a hollow tubular substrate element (40)(140), the hollow tubular substrate element having a multi-layer peripheral wall (42) defining a longitudinal airflow channel (44)(144), wherein the peripheral wall (42) is formed by multiple overlapping layers of homogenized tobacco material, and wherein the longitudinal airflow channel (44)(144) has a diameter of at least 3 mm; and a downstream section (14) disposed downstream of the aerosol generating substrate (12).

Description

Aerosol-generating article comprising a hollow tubular substrate element

Technical Field

The present invention relates to an aerosol-generating article comprising an aerosol-generating substrate suitable for generating an inhalable aerosol upon heating.

Background technique

Aerosol generating articles in which an aerosol generating substrate such as a tobacco-containing substrate is heated rather than burned are known in the art. Typically, in such heated smoking articles, an aerosol is generated by transferring heat from a heat source to a physically separated aerosol generating substrate or material, which may be positioned in contact with, inside, 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 the air drawn by the aerosol generating article. When the released compounds cool, the compounds condense to form an aerosol.

Many prior art documents disclose aerosol generating devices for consuming aerosol generating articles. Such devices include, for example, electrically heated aerosol generating devices, in which an aerosol is generated by transferring heat from one or more electric heater elements of the aerosol generating device to an aerosol generating substrate of a heated aerosol generating article. For example, electrically heated aerosol generating devices including internal heater blades have been proposed, and the internal heater blades are suitable for insertion into the aerosol generating substrate. It is also known to use aerosol generating articles in combination with external heating systems. For example, WO-A-2020/115151 describes the provision of one or more heating elements arranged around the periphery of the aerosol generating article when the aerosol generating article is received in the cavity of the aerosol generating device. As an alternative, WO-A-2015/176898 proposes an inductively heatable aerosol generating article, which includes an aerosol generating substrate and a receptor arranged in the aerosol generating substrate.

In general, it may be difficult to provide efficient heating of an aerosol generating substrate over the entire strip of the entire substrate. The portion of the substrate closest to the heating element will inevitably be heated most efficiently, and the imperfect transfer of heat through the substrate will mean that the portion of the substrate farthest from the heating element may not be heated efficiently. Therefore, the aerosol generation from these portions of the substrate that are not effectively heated is not optimal, and in some cases, the portion of the substrate may not reach a sufficiently high temperature to generate an aerosol during use. For example, in the case of using an external heating element to heat the strip of an aerosol generating substrate, as described above, the central portion of the strip of the aerosol generating substrate is unlikely to generate as much aerosol as the outer portion of the strip, and in some cases, may not generate any aerosol. In a word, the aerosol generation from the aerosol generating strip may therefore be inefficient, wherein a portion of the aerosol generating substrate may be wasted.

Summary of the invention

It is therefore desirable to provide an aerosol-generating article having an aerosol-generating substrate that is adapted to provide more efficient aerosolization of the aerosol-generating substrate and reduce waste of substrate material such as tobacco. It is particularly desirable to provide an article having a relatively simple design that can be manufactured and included in existing product designs in a cost-effective manner. It is also desirable to provide an article that can be easily adapted so that it can be heated in various types of heating devices, including inductive heating devices and resistive heating devices.

The present disclosure relates to an aerosol generating article. The aerosol generating article may include an aerosol generating substrate, which includes a hollow tubular substrate element. The hollow tubular substrate element may have a multi-layer peripheral wall defining a longitudinal airflow channel. The peripheral wall may be formed by a plurality of overlapping layers of homogenized tobacco material. The longitudinal airflow channel may have a diameter of at least 3 mm. The aerosol generating article may also include a downstream section arranged downstream of the aerosol generating substrate.

According to the present invention, an aerosol generating article is provided, which comprises: an aerosol generating substrate, the aerosol generating substrate comprising a hollow tubular substrate element, the hollow tubular substrate element having a multi-layer peripheral wall defining a longitudinal airflow channel, wherein the peripheral wall is formed by multiple overlapping layers of homogenized tobacco material, and wherein the longitudinal airflow channel has a diameter of at least 3 mm; and a downstream section arranged downstream of the aerosol generating substrate.

As used herein, the term "aerosol generating article" refers to a heated article for generating an aerosol, wherein the article includes an aerosol generating substrate that is suitable and intended to be heated or burned to release volatile compounds that can form an aerosol. Such articles are generally referred to as heat-not-burn articles. A conventional cigarette will be ignited when a user applies a flame to one end of the cigarette and draws air through the other end. The local heat provided by the flame and the oxygen in the air drawn through the cigarette causes the end of the cigarette to be ignited, and the resulting combustion generates inhalable smoke. In contrast, in a "heated aerosol generating article", an aerosol is generated by heating an aerosol generating substrate rather than by burning an aerosol generating substrate. Known heated aerosol generating articles include, for example, electrically heated aerosol generating articles and aerosol generating articles in which an aerosol is generated by heat transfer from a combustible fuel element or a heat source to a physically separated aerosol generating substrate.

Also known are aerosol generating articles suitable for use in an aerosol generating system for supplying an aerosol-forming agent to the aerosol generating article. In such a system, the aerosol generating substrate in the aerosol generating article contains significantly less aerosol-forming agent than those aerosol generating substrates that carry and provide substantially all of the aerosol-forming agent used in forming the aerosol during operation.

As used herein, the term "aerosol-generating substrate" refers to a substrate that is capable of releasing volatile compounds that can form an aerosol when heated. The aerosol generated by the aerosol-generating substrate of the aerosol-generating article described herein can be visible or invisible, and can contain vapor (e.g., fine particles of a substance in a gaseous state that is typically liquid or solid at room temperature) and gas and liquid droplets of condensed vapor.

As used herein, the term "homogenized plant material" encompasses any plant material formed by the agglomeration of plant particles. For example, sheets or webs of homogenized tobacco material for aerosol-generating substrates of the present invention can be formed by agglomerating particles of tobacco material, which particles are obtained by pulverizing, grinding or grinding plant material and one or more of optional tobacco leaves and tobacco stems. Homogenized plant material can be produced by casting, extrusion, papermaking technology or other any suitable process known in the art.

As defined above, the present invention provides an aerosol generating article having a novel aerosol generating substrate in the form of a hollow tubular substrate element. The hollow tubular substrate element is formed by a plurality of overlapping layers of homogenized tobacco material, which are combined to form the peripheral wall of the hollow tubular substrate element. The "peripheral" wall of the hollow tubular substrate corresponds to the main wall defining the tubular structure. Preferably, the hollow tubular substrate element consists only of the peripheral wall. Thus, the peripheral wall contains all the homogenized tobacco material that will generate an aerosol when the aerosol generating substrate is heated.

The peripheral wall of the hollow tubular matrix element defines a longitudinal airflow channel, wherein the term "longitudinal" relates to the longitudinal axis of the aerosol generating article. The longitudinal airflow channel has a diameter of at least about 3 millimeters. Preferably, the longitudinal airflow channel is substantially empty so that nothing in the channel may potentially hinder air and aerosol from flowing through the hollow tubular matrix element. In particular, the longitudinal airflow channel is substantially free of tobacco material.

The provision of the aerosol generating substrate of tubular form advantageously enables the amount of tobacco material in the aerosol generating substrate to be optimized, so that an aerosol can be effectively generated from the aerosol generating substrate when heated. The tubular form also removes the central portion of the homogenized tobacco material, which may not be heated as effectively as the outer portion, particularly in an aerosol generating device comprising an external heating device. In a word, compared with the conventional solid rod of homogenized tobacco material, the amount of tobacco material can therefore be significantly reduced, and tobacco waste can be reduced. For example, it has been found that the amount of tobacco material used in the matrix solid rod in the conventional aerosol generating article can be reduced by up to 40% for the hollow tubular substrate element of the aerosol generating article according to the present invention, while keeping the aerosol similar to be delivered to the consumer.

By controlling the parameters of the hollow tubular substrate element, such as the density and wall thickness of the peripheral wall, the amount of tobacco material provided in the substrate can be easily modified. In this way, it is possible to modify the hollow tubular substrate element so that it matches the heating zone of the associated aerosol generating device. Thus, the proportion of the aerosol generating substrate that can be heated to the required temperature for aerosol generation can be maximized, so that the generation of aerosol from the aerosol generating substrate is optimized.

The hollow tubular matrix element is formed by a plurality of overlapping layers of homogenized tobacco material.Preferably, a plurality of overlapping layers of homogenized tobacco material directly overlie each other, so that adjacent layers directly contact each other, and there is no intermediate layer.A plurality of overlapping layers of homogenized tobacco material can advantageously be arranged to limit a plurality of spaces between adjacent layers.Therefore, the peripheral wall has a porous structure usually.As described in more detail below, the space between the adjacent layers of the homogenized tobacco material that is limited can advantageously provide transverse porosity and longitudinal porosity, so that the aerosol generated when the heated aerosol generates the matrix is effectively released in the longitudinal airflow channel and flows through the passage, mixes with external air, and the external air is sucked through the goods when the consumer sucks.

The multilayer arrangement of layers further provides a relatively dense structure having sufficient structural rigidity to provide the aerosol-generating substrate in an aerosol-generating article without the need for any additional support, such as a carrier layer or internal support members within the longitudinal airflow channels.

Providing longitudinal airflow channels having a diameter of at least about 3 mm also advantageously provides greater control over the management of airflow through the aerosol-generating article.

The hollow tubular substrate element has a relatively simple structure that can be produced in a simple and cost-effective manner using existing equipment.The hollow tubular substrate element can then be included into an aerosol-generating article together with other components using known assembly methods and equipment.

Advantageously, if desired, the hollow tubular substrate element may be incorporated directly into an aerosol-generating article without an outer wrapper. This provides a unique appearance and texture to the outer surface of the aerosol-generating substrate.

As described above, the hollow tubular substrate element forming the aerosol-generating substrate of an aerosol-generating article according to the invention is formed from a plurality of overlapping layers of homogenised tobacco material. These layers overlap each other in a transverse direction so as to provide a multi-layer structure.

Preferably, the hollow tubular substrate element comprises at least about 2 overlapping layers of homogenized tobacco material, more preferably at least about 3 overlapping layers of homogenized tobacco material.

Preferably, the hollow tubular matrix element comprises up to about 10 overlapping layers of homogenized tobacco material, more preferably up to about 5 overlapping layers of homogenized tobacco material. For example, the hollow tubular matrix element can comprise from about 2 to about 10 overlapping layers of homogenized tobacco material, or from about 3 to about 5 overlapping layers of homogenized tobacco material.

As described above, the peripheral wall of the hollow tubular substrate element preferably has a porous structure due to the voids formed between the overlapping layers of homogenised tobacco material.Preferably, the peripheral wall is porous both laterally and longitudinally.

Preferably, the peripheral wall of the hollow tubular matrix element has a cross-sectional porosity of at least about 0.3, more preferably at least about 0.35, and most preferably at least about 0.4.

Preferably, the peripheral wall has a cross-sectional porosity of up to about 0.7, more preferably up to about 0.65, most preferably up to about 0.6.

For example, the cross-sectional porosity of the peripheral wall may be between about 0.3 and about 0.7, or between about 0.35 and about 0.65, or between about 0.4 and about 0.6.

As used herein, the term "porosity" refers to the fraction of void space in a gas permeable or porous body. Specifically, in the context of the present invention, the term "cross-sectional porosity" refers to the fraction of void space in the cross-sectional area of the peripheral wall of the hollow tubular matrix element. The cross-sectional porosity is the area fraction of void space in the cross-sectional area of the peripheral wall. The cross-sectional area of the peripheral wall is the area of the peripheral wall in a plane perpendicular to the longitudinal axis of the hollow tubular matrix element.

The cross-sectional porosity of the peripheral wall enables the aerosol to pass through the peripheral wall in a transverse direction so that it can be drawn into and through the longitudinal airflow channel.

Further details on measuring cross-sectional porosity in porous or gas permeable bodies can be found in International patent application WO-A-2016/023965 published in the name of the present applicant.

Advantageously, a digital imaging process may be used to determine the cross-sectional porosity. An image of a cross-section of the hollow tubular substrate may be obtained, and a threshold may be applied to distinguish pixels representing the aerosol-forming substrate from pixels representing void spaces. The cross-sectional porosity is calculated according to the following equation: _Po = _Nvoid / _Ntotal , where _Po is the overall porosity of the cross-sectional area, _Nvoid is the number of pixels representing void space within the cross-sectional area and Ntotal _is the total number of pixels in the cross-sectional area.

Note that the digital image acquisition can be accomplished by any suitable method, such as by utilizing a digital camera or computed tomography. The images can be represented by any suitable image format, in full RGB (red-green-blue) color, grayscale, or binary (black and white) representation. Preferably, the background in any image is uniform to aid in detecting and removing the background during image processing. The resolution of any image should be high enough to accurately resolve the morphology of the hollow tubular matrix.

Preferably, the peripheral wall of the hollow tubular matrix element has a density of at least about 200 mg/cm3, more preferably at least about 300 mg/cm3, more preferably at least about 400 mg/cm3, more preferably at least about 500 mg/cm3, more preferably at least about 600 mg/cm3, more preferably at least about 700 mg/cm3, more preferably at least about 800 mg/cm3.

Preferably, the peripheral wall of the hollow tubular matrix element has a density of less than about 1 g/cm3.

In the context of the present invention, "density" refers to the overall density of the peripheral wall including overlapping layers, rather than the density of each layer. The relatively high density of the peripheral wall maximizes the amount of tobacco material that can be provided for a given length of aerosol-generating substrate, so that the amount of aerosol generated by the hollow tubular substrate element can be maximized.

Preferably, the perimeter wall provides at least about 150 mg of the homogenized tobacco material/cm length of the hollow tubular matrix, more preferably at least about 200 mg of the homogenized tobacco material/cm length, more preferably at least about 300 mg of the homogenized tobacco material/cm length, more preferably at least about 400 mg of the homogenized tobacco material/cm length, more preferably at least about 500 mg of the homogenized tobacco material/cm length, more preferably at least about 600 mg of the homogenized tobacco material/cm length, more preferably at least about 700 mg of the homogenized tobacco material/cm length, more preferably at least about 800 mg of the homogenized tobacco material/cm length. This is based on the measurement carried out under 22.5 degrees Celsius, 60% humidity.

Preferably, the longitudinal tensile strength of the hollow tubular matrix element measured according to TAPPI test method T494 om-01 2006 is between 11 kN/m and 14 kN/m.

Preferably, the axial compressive strength of the hollow tubular matrix element measured according to the test method described in ASTM D695-15 (2018) is between 7 MPa and 9 MPa.

Preferably, the radial compressive strength of the hollow tubular matrix element measured according to the test method described in ASTM D2412-11 (2018) is between 7 MPa and 9 MPa.

Preferably, the hollow tubular matrix element has a length of at least about 10 mm, more preferably at least about 12 mm, more preferably at least about 15 mm.

Preferably, the hollow tubular matrix element has a length of up to about 40 mm, more preferably up to about 37 mm, more preferably up to about 35 mm.

For example, the hollow tubular matrix element can have a length of between about 10 mm and about 40 mm, or between about 12 mm and about 37 mm, or between about 15 mm and about 35 mm.

As discussed above, the length of the hollow tubular substrate element may advantageously match the longitudinal dimension of a heating element in a corresponding aerosol generating device to be used to heat the aerosol generating article. In this way, as much of the aerosol generating substrate as possible may be heated during use in order to optimize the amount of aerosol that can be generated and reduce the amount of tobacco waste.

Preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least about 0.15. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least about 0.25. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least about 0.4.

Preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is up to about 0.6. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is up to about 0.55. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is up to about 0.5.

For example, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be between about 0.15 and about 0.6, more preferably between about 0.25 and about 0.55, more preferably between about 0.4 and about 0.5.

Preferably, the hollow tubular matrix element has an outer diameter of at least about 4 mm, more preferably at least about 4.25 mm, and more preferably at least about 4.5 mm.

Preferably, the hollow tubular matrix element has an outer diameter of up to about 9 mm, more preferably up to about 8 mm and more preferably up to about 7.5 mm.

For example, the hollow tubular matrix element can have an outer diameter of between about 4 mm and about 9 mm, or between about 4.25 mm and about 8 mm, or between about 4.5 mm and about 7.5 mm.

Preferably, the outer diameter of the hollow tubular substrate element is substantially the same as the outer diameter of the aerosol-generating article.

As described above, the hollow tubular matrix element provides a longitudinal airflow channel defined by the peripheral wall. The longitudinal airflow channel extends between the ends of the hollow tubular matrix element and is preferably open at both the upstream end and the downstream end. The open upstream end provides a primary air inlet for drawing air through the aerosol generating article when a consumer draws on the article. Thus, the longitudinal airflow channel provides a primary pathway for air and aerosol to flow through the article.

Preferably, the hollow tubular matrix element provides an unrestricted flow channel. This means that the hollow tubular matrix 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 /10 mm length of the hollow tubular element, preferably less than 0.4 mm _H2O /10 mm length of the hollow tubular element, more preferably less than 0.1 mm _H2O /10 mm length of the hollow tubular element.

The longitudinal air flow channel has a diameter of at least 3 mm. This corresponds to the inner diameter of the hollow tubular matrix element. Preferably, the longitudinal air flow channel has a diameter of at least about 3.25 mm, more preferably at least about 3.5 mm.

Preferably, the longitudinal air flow channels have a diameter of up to about 7 mm, more preferably up to about 6 mm, more preferably up to about 5.5 mm.

For example, the longitudinal air flow channels may have a diameter between about 3 mm and about 7 mm, or between about 3.25 mm and about 6 mm, or between about 3.5 mm and about 5.5 mm.

Providing an airflow channel with a minimum diameter of 3 mm enables the volume of the channel to be large enough to provide the desired level of airflow while also maintaining a sufficient wall thickness. This is necessary to provide a sufficient amount of tobacco material within the hollow tubular matrix element and to provide the hollow tubular matrix element with a sufficiently high rigidity so that it can be self-supporting.

The longitudinal air flow channels may have a constant diameter along the length of the hollow tubular matrix element. However, the diameter of the longitudinal air flow channels may vary along the length of the hollow tubular matrix element.

Preferably, the longitudinal airflow channel has a substantially circular cross-section.Alternatively, the longitudinal airflow channel may have a substantially oval cross-section.

Preferably, the ratio of the inner diameter to the outer diameter of the hollow tubular matrix element is at least about 0.4, more preferably at least about 0.45, and more preferably at least about 0.5.

Preferably, the outer diameter of the hollow tubular matrix element and the diameter of the longitudinal gas flow channel are adapted to provide the desired wall thickness for the peripheral wall. Preferably, the peripheral wall has a wall thickness of at least about 1 mm, more preferably at least about 1.25 mm and more preferably at least about 1.5 mm.

Preferably, the peripheral wall has a wall thickness of up to about 2.25 mm, more preferably up to about 2 mm, more preferably up to about 1.8 mm.

For example, the peripheral wall may have a thickness between 1 millimeter and about 2.25 millimeters, or between about 1.25 millimeters and about 2 millimeters, or between about 1.5 millimeters and about 1.8 millimeters.

The overlapping layers of homogenized tobacco material can be arranged in any suitable manner to provide the desired wall thickness and porosity for the peripheral wall. Each layer of homogenized tobacco material will generally extend around the hollow tubular matrix element at least once, and preferably, each layer of homogenized tobacco material extends around the hollow tubular matrix element multiple times to build the structure of the peripheral wall.

Preferably, the multi-layer homogenized tobacco material is spirally wound around the longitudinal axis of the hollow tubular substrate element. This provides a spirally wound structure similar to the layered structure of a conventional paper straw. The hollow tubular substrate element including the spiral arrangement of the layers for the present invention can be manufactured using existing straw manufacturing equipment, such as the Hauni Straw Maker (HSM) from Hauni Maschinenbau GmbH.

Compared with similar structures with simple longitudinal wrapping, the use of the spiral winding structure provides the best structural strength to the hollow tubular matrix element, with increased mechanical strength in all directions. In addition, the spiral winding arrangement makes it possible to obtain a higher density of homogenized tobacco material in the peripheral wall. The manufacturing method for the spiral arrangement of the production layer provides a greater control of the size of the hollow tubular matrix element in addition, so that the variation of the outer diameter and the inner diameter is minimized. This provides greater consistency between products.

Optionally, the hollow tubular matrix element may include an adhesive for sealing adjacent layers to each other. Suitable adhesives are known to those skilled in the art. Preferably, the adhesive is a water-based adhesive, such as a water-based starch adhesive or a polyvinyl alcohol (PVOH) adhesive.

In certain embodiments of the present invention, the aerosol generating substrate may also include a sealing element at the upstream end of the hollow tubular substrate element, which covers the upstream end of the hollow tubular substrate element. In such embodiments, the open upstream end of the hollow tubular substrate element is therefore covered and sealed by the sealing element so that air cannot be drawn into the longitudinal airflow channel. Therefore, the sealing element needs to be suitable so that it can be removed or pierced before use, so as to open the upstream end of the hollow tubular substrate element and also allow air to enter the longitudinal airflow channel.

Preferably, the peripheral wall of the hollow tubular matrix element formed by overlapping layers of homogenized tobacco material is at least partially exposed on the outer surface of the hollow tubular matrix element. Thus, the hollow tubular matrix element is preferably not wrapped along at least a portion of its length. The outer surface of the peripheral wall should provide an acceptable surface to form the exterior of the aerosol-generating article, and the layered structure can provide a unique appearance and texture.

Alternatively, the hollow tubular matrix element may be wrapped with at least one wrapper. For example, the hollow tubular matrix element may be wrapped with a conventional paper wrapper. The hollow tubular matrix element may be wrapped with a tobacco-containing wrapper such as a tobacco paper wrapper.

The hollow tubular substrate element is formed from multiple layers of homogenised tobacco material, preferably in sheet form.As used herein with reference to the present invention, the term "sheet" describes a laminar element having a width and length substantially greater than its thickness.

The sheets may each individually have a thickness of between 100 and 600 microns, preferably between 150 and 300 microns, and most preferably between 200 and 250 microns.

Homogenized tobacco material comprises tobacco particles.Sheets of homogenized tobacco material for use in the present invention can have a tobacco content of at least about 40 wt % on a dry weight basis, more preferably at least about 50 wt % on a dry weight basis, more preferably at least about 70 wt % on a dry weight basis, and most preferably at least about 90 wt % on a dry weight basis.

With reference to the present invention, the particle of any plant member of the Nicotiana genus is described in term " tobacco particles ".Term " tobacco particles " comprises ground or pulverized tobacco blade, ground or pulverized tobacco leaf stem, tobacco dust, tobacco fines and other granular tobacco by-products formed in the processing, operation and transportation process of tobacco.In a preferred embodiment, tobacco particles are all derived from tobacco blade basically.By contrast, isolated nicotine and nicotine salt are compounds derived from tobacco, but are not considered to tobacco particles for purposes of the present invention, and are not included in the percentage of granular plant material.

Homogenized tobacco material can also include one or more aerosol forming agents. When volatilized, aerosol forming agents can transmit other vaporized compounds such as nicotine and flavoring agents released from aerosol generating substrate when heated in aerosol. Suitable aerosol forming agents included in homogenized plant material are known in the art, and include but are not limited to: polyols, such as triethylene glycol, propylene glycol, 1,3-butylene glycol and glycerine; esters of polyols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

Homogenized tobacco material can have between about 5 wt % and about 30 wt % on a dry weight basis, for example between about 10 wt % and about 25 wt % on a dry weight basis, or between about 15 wt % and about 20 wt % on a dry weight basis. Aerosol forming agent can act as a humectant in the homogenized tobacco material.

Two or more overlapping layers of the homogenized tobacco material of the perimeter wall that forms the hollow tubular matrix element can all be formed by identical homogenized tobacco material.Alternately, the perimeter wall comprises one or more layers of the first homogenized tobacco material and one or more layers of the second homogenized tobacco material that is different from the first homogenized tobacco material.Therefore, the perimeter wall is formed by the combination of at least two different homogenized tobacco materials.The first homogenized tobacco material and the second homogenized tobacco material can be different from each other in composition.For example, the first homogenized tobacco material and the second homogenized tobacco material can have tobacco contents different from each other, or different aerosol forming agent contents, or both.Alternately or in addition, the first homogenized tobacco material and the second homogenized tobacco material have been provided with different levels of flavoring agents, so that flavor characteristics are provided.Alternately or in addition, the first homogenized tobacco material and the second homogenized tobacco material can be different from each other aspect one or more physical parameters, and described physical parameters include but not limited to density, porosity or thickness.

In the hollow tubular matrix element, using different homogenized tobacco materials provides greater flexibility in delivering aerosol when heating. For example, the composition of the first homogenized tobacco material and the second homogenized tobacco material can be suitable for providing the delivery of aerosol at different times or different speeds. Using different homogenized tobacco materials can also for example provide improved stability by avoiding the combination of potential incompatible components.

Preferably, the multi-layer homogenised tobacco material comprises one or more cast lamina.

Preferably, the casting leaf has a porosity at 25 degrees Celsius of between about 20% and about 60%, more preferably between about 30% and about 50%, more preferably between about 35% and about 45%.

In lieu of or in addition to one or more cast leaf sheets, the multiple layers of homogenized tobacco material may include one or more layers of cigarillo paper.

Preferably, the cigarillo paper has a porosity at 25 degrees Celsius of between about 30% and about 80%, more preferably between about 40% and about 70%, more preferably between about 50% and about 60%.

The peripheral wall may be formed from alternating layers of cast leaf and cigarillo paper.

The hollow tubular substrate element of aerosol-generating articles according to the invention preferably comprises one or more susceptor elements positioned in contact with the peripheral wall for inductively heating the homogenised tobacco material during use.

As used herein, the term "susceptor element" refers to an element comprising a material capable of converting electromagnetic energy into heat. When the susceptor element is located in an alternating electromagnetic field, the susceptor is heated. The heating of the susceptor element may be the result of at least one of hysteresis losses and eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material.

The susceptor element may be arranged such that when the aerosol generating article is received in the cavity of the aerosol generating device, the oscillating electromagnetic field generated by the inductor coil induces a current in the susceptor element, thereby causing the susceptor element to heat up. In these embodiments, the aerosol generating device is preferably capable of generating a fluctuating electromagnetic field having a magnetic field strength (H field strength) of between 1 kiloamperes per meter and 5 kiloamperes per meter (kA m), preferably between 2 kA/m and 3 kA/m, for example about 2.5 kA/m. Preferably, the electrically operated aerosol generating device is capable of generating a fluctuating electromagnetic field having a frequency of between 1 MHz and 30 MHz, for example between 1 MHz and 10 MHz, for example between 5 MHz and 7 MHz.

The susceptor element may comprise any suitable material. The susceptor element may be formed of any material that can be inductively heated to a temperature sufficient to release volatile compounds from the aerosol generating substrate. Suitable materials for the elongated susceptor element include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and metal material composites. Some susceptor elements include metal or carbon. Advantageously, the susceptor element may include or consist of a ferromagnetic material, such as ferritic iron, ferromagnetic alloys (e.g., ferromagnetic steel or stainless steel), ferromagnetic particles, and ferrites. Suitable susceptor elements may be aluminum or include aluminum. The susceptor element preferably comprises greater than about 5%, preferably greater than about 20%, more preferably greater than about 50%, or greater than about 90% ferromagnetic or paramagnetic material. Some elongated susceptor elements may be heated to a temperature exceeding about 250 degrees Celsius.

The susceptor element may comprise a non-metallic core with a metallic layer disposed thereon.For example, the susceptor element may comprise a metallic track formed on the outer surface of a ceramic core or substrate.

Preferably, the hollow tubular matrix element comprises one or more susceptor elements on the surface of the peripheral wall. The hollow tubular matrix element may comprise one or more susceptor elements on the inner surface of the peripheral wall within the longitudinal airflow channel. Alternatively or in addition, the hollow tubular matrix element may comprise one or more susceptor elements on the outer surface of the peripheral wall.

Preferably, the hollow tubular matrix element comprises a tubular susceptor element disposed on at least one surface of the peripheral wall. The tubular susceptor element may be disposed on the inner surface of the peripheral wall to heat the hollow tubular matrix element from the inside. Alternatively, the tubular susceptor element may be disposed on the outer surface of the hollow tubular matrix element to heat the hollow tubular matrix element from the outside.

The use of a tubular susceptor element advantageously optimizes the heating of the homogenized tobacco material within the peripheral wall, because the susceptor element contacts a relatively large surface area of the homogenized tobacco material. Due to the tubular form of the hollow tubular substrate element, the thickness of the substrate is relatively low, so that heat can be effectively transferred through the peripheral wall from the side where the tubular susceptor element is located.

As defined above, in the aerosol-generating article of the present invention, the aerosol-generating substrate formed by the hollow tubular substrate element is combined with a downstream section located downstream of the aerosol-generating substrate. Preferably, the downstream section is located immediately downstream of the aerosol-generating substrate. Preferably, the downstream section of the aerosol-generating article extends between the aerosol-generating substrate and the downstream end of the aerosol-generating article. The downstream section may include one or more elements, each of which will be described in more detail within the present disclosure.

Preferably, the downstream section comprises at least one hollow tubular element. The hollow tubular element may be arranged immediately downstream of the aerosol-generating substrate. In other words, the hollow tubular element may abut the downstream end of the aerosol-generating substrate. This arrangement optimizes the flow of aerosol from the longitudinal airflow channel of the hollow tubular substrate element into the downstream section and through the aerosol-generating article.

Preferably, the downstream section of the aerosol-generating article comprises a single hollow tubular element. In other words, the downstream section of the aerosol-generating article may comprise only one hollow tubular element.

As used throughout this disclosure, a "hollow tubular element" refers to a generally elongated element that defines a lumen or airflow passage along its longitudinal axis. In particular, the term "tubular" will hereinafter be used to refer to a tubular element having a substantially cylindrical cross-section and defining at least one airflow conduit that establishes uninterrupted fluid communication between an upstream end of the tubular element and a downstream end of the tubular element. However, it should be understood that alternative geometries of the tubular element (e.g., alternative cross-sectional shapes) may be possible. The hollow tubular element may be a single discrete element of the aerosol-generating article having a defined length and thickness.

In the context of the present invention, the hollow tubular element of the downstream section provides an unrestricted flow passage through the airflow passage. This means that the hollow tubular element provides a negligible level of resistance to draw (RTD) as defined above. Therefore, the airflow passage should be free of any components that hinder the flow of air in the longitudinal direction. Preferably, the airflow passage is substantially empty.

The hollow tubular element of the downstream section provides a cavity downstream of the aerosol-generating substrate, which enhances the cooling and nucleation of aerosol particles generated by the aerosol-generating substrate. Thus, the hollow tubular element of the downstream section acts as an aerosol-cooling element.

The length of the hollow tubular element may be at least about 12 mm. The length of the hollow tubular element may be at least about 15 mm. The length of the hollow tubular element may be at least about 20 mm.

The length of the hollow tubular element of the downstream section may be less than or equal to about 50 mm. The length of the hollow tubular element may be less than or equal to about 45 mm. The length of the hollow tubular element may be less than or equal to about 40 mm.

For example, the length of the hollow tubular element of the downstream section may be between about 12 mm and 50 mm. The length of the hollow tubular element may be between about 15 mm and 45 mm. The length of the hollow tubular element may be between about 20 mm and 40 mm. The length of the hollow tubular element may be about 30 mm.

A relatively long hollow tubular element is provided within the downstream section of the aerosol-generating article and defines a relatively long internal lumen.Providing a relatively long lumen maximizes the above-mentioned nucleation benefits, thereby improving aerosol formation and cooling.

The ratio between the length of the hollow tubular matrix element and the length of the hollow tubular element of the downstream section may be less than or equal to about 1.25. Preferably, the ratio between the length of the hollow tubular matrix element and the length of the hollow tubular element of the downstream section may be less than or equal to about 1. More preferably, the ratio between the length of the hollow tubular matrix element and the length of the hollow tubular element of the downstream section may be less than or equal to about 0.75.

The ratio between the length of the hollow tubular matrix element and the length of the hollow tubular element of the downstream section may be at least about 0.25. Preferably, the ratio between the length of the hollow tubular matrix element and the length of the hollow tubular element of the downstream section may be at least about 0.30. More preferably, the ratio between the length of the hollow tubular matrix element and the length of the hollow tubular element of the downstream section may be at least about 0.40.

For example, the ratio between the length of the hollow tubular matrix element and the length of the hollow tubular element of the downstream segment may be between about 0.25 and about 1.25, or between about 0.3 and about 1, or between about 0.4 and about 0.75.

The ratio between the length of the hollow tubular element of the downstream section and the total length of the downstream section may be less than or equal to about 1. Preferably, the ratio between the length of the hollow tubular element of the downstream section and the total length of the downstream section may be less than or equal to about 0.90. More preferably, the ratio between the length of the hollow tubular element of the downstream section and the total length of the downstream section may be less than or equal to about 0.85.

The ratio between the length of the hollow tubular element of the downstream section and the total length of the downstream section may be at least about 0.35. Preferably, the ratio between the length of the hollow tubular element of the downstream section and the total length of the downstream section may be at least about 0.45. More preferably, the ratio between the length of the hollow tubular element of the downstream section and the total length of the downstream section may be at least about 0.50.

For example, the ratio between the length of the hollow tubular element of the downstream section and the total length of the downstream section may be between about 0.35 and about 1, or between about 0.45 and about 0.9, or between about 0.5 and about 0.85.

The ratio between the length of the hollow tubular element of the downstream section and the overall length of the aerosol-generating article may be less than or equal to about 0.80. Preferably, the ratio between the length of the hollow tubular element of the downstream section and the overall length of the aerosol-generating article may be less than or equal to about 0.70. More preferably, the ratio between the length of the hollow tubular element of the downstream section and the overall length of the aerosol-generating article may be less than or equal to about 0.60.

The ratio between the length of the hollow tubular element of the downstream section and the overall length of the aerosol-generating article may be at least about 0.25. Preferably, the ratio between the length of the hollow tubular element of the downstream section and the overall length of the aerosol-generating article may be at least about 0.30. More preferably, the ratio between the length of the hollow tubular element of the downstream section and the overall length of the aerosol-generating article may be at least about 0.40.

For example, the ratio between the length of the hollow tubular element of the downstream section and the overall length of the aerosol-generating article may be between about 0.25 and about 0.8, or between about 0.3 and about 0.7, or between about 0.4 and about 0.6.

The wall thickness of the hollow tubular element of the downstream section may be at least about 100 microns. The wall thickness of the hollow tubular element of the downstream section may be at least about 150 microns. The wall thickness of the hollow tubular element of the downstream section may be at least about 200 microns, preferably at least about 250 microns and even more preferably at least about 500 microns (or 0.5 mm).

The wall thickness of the hollow tubular element of the downstream section may be less than or equal to about 2 mm, preferably less than or equal to about 1.5 mm and even more preferably less than or equal to about 1.25 mm. The wall thickness of the hollow tubular element of the downstream section may be less than or equal to about 1 mm. The wall thickness of the hollow tubular element of the downstream section may be less than or equal to about 500 microns.

The wall thickness of the hollow tubular element of the downstream section may be between about 100 micrometers and about 2 millimeters, preferably between about 150 micrometers and about 1.5 millimeters, even more preferably between about 200 micrometers and about 1.25 millimeters.

Keeping the wall thickness of the hollow tubular element in the downstream section relatively low ensures the overall internal volume of the hollow tubular element (which allows the aerosol nucleation process to begin once the aerosol components leave the aerosol generating substrate), and the cross-sectional surface area of the longitudinal airflow channel of the hollow tubular element is effectively maximized, while ensuring that the hollow tubular element has the necessary structural strength to prevent collapse of the aerosol generating article and provide some support for the strips of the aerosol generating substrate, and the RTD of the hollow tubular element is minimized. Larger values of the cross-sectional surface area of the cavity of the hollow tubular element should be understood to be associated with a reduced velocity of the aerosol flow traveling along the aerosol generating article, which is also expected to be beneficial to aerosol nucleation. In addition, it seems that by utilizing a hollow tubular element with a relatively low thickness, the ventilation air can be substantially prevented from diffusing before it contacts and mixes with the aerosol flow, which is also understood to be further beneficial to the nucleation phenomenon. In practice, the effect of cooling on the formation of new aerosol particles can be enhanced by providing more controlled local cooling of the volatile substance flow.

Preferably, the hollow tubular element of the downstream section has an outer diameter substantially equal to the outer diameter of the aerosol-generating substrate and the outer diameter of the aerosol-generating article.

The hollow tubular element may have an outer diameter between about 5 mm and about 12 mm, for example between about 5 mm and about 10 mm or between about 6 mm and about 8 mm.Preferably, the hollow tubular element has an outer diameter of 7.2 mm +/- 10%.

The hollow tubular element of the downstream section may have a constant inner diameter along the length of the hollow tubular element.However, the inner diameter of the hollow tubular element may vary along the length of the hollow tubular element.

The hollow tubular element of the downstream section may have an inner diameter of at least about 2 mm. For example, the hollow tubular element may have an inner diameter of at least about 2.5 mm, at least about 3 mm, or at least about 3.5 mm. Providing a hollow tubular element with an inner diameter as described above can advantageously provide the hollow tubular element with sufficient rigidity and strength.

The hollow tubular element of the downstream section may have an inner diameter of no more than about 10 mm. For example, the hollow tubular element may have an inner diameter of no more than about 9 mm, no more than about 8 mm, or no more than about 7.5 mm. Providing a hollow tubular element with an inner diameter as described above can advantageously reduce the suction resistance of the hollow tubular element.

For example, the hollow tubular element of the downstream section may have an inner diameter between about 2 mm and about 10 mm, between about 2.5 mm and about 9 mm, between about 3 mm and about 8 mm, or between about 3.5 mm and about 7.5 mm.

The ratio of the inner diameter of the hollow tubular matrix element to the inner diameter of the hollow tubular element of the downstream section is preferably between about 0.8 and about 1.2, more preferably between about 0.9 and about 1.1, and most preferably about 1.

Particularly preferably, the inner diameter of the hollow tubular matrix element is substantially equal to the inner diameter of the hollow tubular element of the downstream section.

The hollow tubular element of the downstream section may comprise a paper-based material. The hollow tubular element may comprise at least one paper layer. The paper may be a very hard paper. The paper may be a curled paper, such as a curled heat-resistant paper or a curled parchment paper.

Preferably, the hollow tubular element may comprise paperboard. The hollow tubular element may be a paperboard tube. The hollow tubular element may be formed from paperboard. Advantageously, paperboard is a cost-effective material that provides a balance between being deformable to provide ease of insertion of the article into the aerosol generating device and being sufficiently rigid to provide appropriate engagement of the article with the interior of the device. Thus, the paperboard tube may provide suitable resistance to deformation or compression during use.

The hollow tubular element may be a paper tube. The hollow tubular element may be a tube formed by spirally winding paper. The hollow tubular element may be formed from multiple paper layers. The paper may have a basis weight of at least about 50 g/m2, at least about 60 g/m2, at least about 70 g/m2, or at least about 90 g/m2.

The hollow tubular element of the downstream section may include a polymer material. For example, the hollow tubular element may include a polymer film. The polymer film may include a cellulose film. The hollow tubular element may include low density polyethylene (HDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may contain cellulose acetate tow.

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.

In some embodiments, aerosol-generating articles according to the invention may comprise a ventilation zone at a location along the downstream section. In more detail, in those embodiments in which the downstream section comprises a hollow tubular element, the ventilation zone may be provided at a location along the hollow tubular element.

Thus, the ventilation cavity is arranged downstream of the strip of aerosol-generating substrate. This provides a particularly effective cooling of the aerosol and promotes enhanced nucleation of aerosol particles.

The ventilation zone may typically comprise a plurality of perforations through the circumferential wall of the hollow tubular element. Preferably, the ventilation zone comprises at least one row of circumferential perforations. In some embodiments, the ventilation zone may comprise two rows of circumferential perforations. For example, the perforations may be formed on a production line during manufacture of the aerosol-generating article. Preferably, each row of circumferential perforations comprises 8 to 30 perforations.

The downstream section may further comprise a mouthpiece element. The mouthpiece element may be located at the downstream end of the aerosol-generating article. Preferably, the mouthpiece element is located downstream of the hollow tubular element of the downstream section, which is described above. The mouthpiece element may extend between the hollow tubular element of the downstream section and the downstream end of the aerosol-generating article.

Providing a mouthend element at the downstream end of an aerosol-generating article according to the present invention provides an attractive appearance and mouthfeel to the consumer.

The mouthpiece element may comprise at least one mouthpiece filter segment formed of a fibrous filter material.Parameters or characteristics described in relation to the mouthpiece element as a whole may equally apply to the mouthpiece filter segment of the mouthpiece element.

The fibrous filter material may be used to filter the aerosol generated by the aerosol generating substrate. Suitable fibrous filter materials will be known to the skilled person. Particularly preferably, at least one of the mouthpiece filter segments comprises a cellulose acetate filter segment formed from cellulose acetate tow.

The mouthpiece element may be comprised of a single mouthpiece filter segment.The mouthpiece element may comprise two or more mouthpiece filter segments axially aligned with each other in an abutting end-to-end relationship.

The downstream section may include a mouth end cavity at the downstream end downstream of the mouthpiece element as described above. The mouth end cavity may be defined by a further hollow tubular element disposed at the downstream end of the mouthpiece element. The mouth end cavity may be defined by an outer wrapper of the aerosol generating article, wherein the outer wrapper extends from (or through) the mouthpiece element in the downstream direction.

The mouthpiece element may optionally include a flavoring agent, which may be provided in any suitable form. For example, the mouthpiece element may include one or more capsules, beads or particles of a flavoring agent, or one or more threads or filaments loaded with a flavoring agent.

Preferably, the mouthpiece element or mouthpiece filter segment thereof has a low particle filtration efficiency.

Preferably, the mouthend element is defined by a rod wrap.Preferably, the mouthend element is non-ventilated, such that air does not enter the aerosol-generating article along the mouthend element.

Preferably, the mouthpiece element has an outer diameter substantially equal to the outer diameter of the aerosol generating article. The diameter of the mouthpiece element (or mouthpiece filter segment) may be substantially the same as the outer diameter of the hollow tubular element. As mentioned in the present disclosure, the outer diameter of the hollow tubular element may be about 7.2 mm ± 10%.

The diameter of the mouthpiece element may be between about 5 mm and about 10 mm. The diameter of the mouthpiece element may be between about 6 mm and about 8 mm. The diameter of the mouthpiece element may be between about 7 mm and about 8 mm. The diameter of the mouthpiece element may be about 7.2 mm ± 10%. The diameter of the mouthpiece element may be about 7.25 mm ± 10%.

Unless otherwise stated, the draw resistance (RTD) of a component or aerosol generating article is measured in accordance with ISO6565-2015. RTD refers to the pressure required to force air through the full length of the component. The term "pressure drop" or "draw resistance" of a component or article may also refer to "resistance to draw". Such terms generally refer to measurements in accordance with ISO6565-2015. Generally, in the test, 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 output or downstream end of the measuring component is measured at a volume flow rate of about 17.5 ml/sec.

The resistance to draw (RTD) of the downstream section may be at least about 0 mm H ₂ O. The RTD of the downstream section may be at least about 3 mm H ₂ O. The RTD of the downstream section may be at least about 6 mm H ₂ O.

The RTD of the downstream section may be no greater than about 12 mm H ₂ O. The RTD of the downstream section may be no greater than about 11 mm H ₂ O. The RTD of the downstream section may be no greater than about 10 mm H ₂ O.

The suction resistance of the downstream section may be greater than or equal to about 0 mm H ₂ O and less than about 12 mm H ₂ O. Preferably, the suction resistance of the downstream section may be greater than or equal to about 3 mm H ₂ O and less than about 12 mm H ₂ O. The suction resistance of the downstream section may be greater than or equal to about 0 mm H ₂ O and less than about 11 mm H ₂ O. Even more preferably, the suction resistance of the downstream section may be greater than or equal to about 3 mm H ₂ O and less than about 11 mm H ₂ O. Even more preferably, the suction resistance of the downstream section may be greater than or equal to about 6 mm H ₂ O and less than about 10 mm H ₂ O. Preferably, the suction resistance of the downstream section may be about 8 mm H ₂ O.

The resistance to draw (RTD) characteristics of the downstream section may be entirely or primarily attributable to the RTD characteristics of the mouthpiece element of the downstream section. In other words, the RTD of the mouthpiece element of the downstream section may entirely define the RTD of the downstream section.

The resistance to draw (RTD) of the mouthpiece element may be at least about 0 mm H ₂ O. The RTD of the mouthpiece element may be at least about 3 mm H ₂ O. The RTD of the mouthpiece element may be at least about 6 mm H ₂ O.

The RTD of the mouthpiece element may be no greater than about 12 mm H ₂ O. The RTD of the mouthpiece element may be no greater than about 11 mm H ₂ O. The RTD of the mouthpiece element may be no greater than about 10 mm H ₂ O.

The draw resistance of the mouthpiece element may be greater than or equal to about 0 mm H ₂ O and less than about 12 mm H ₂ O. Preferably, the draw resistance of the mouthpiece element may be greater than or equal to about 3 mm H ₂ O and less than about 12 mm H ₂ O. The draw resistance of the mouthpiece element may be greater than or equal to about 0 mm H ₂ O and less than about 11 mm H ₂ O. Even more preferably, the draw resistance of the mouthpiece element may be greater than or equal to about 3 mm H ₂ O and less than about 11 mm H ₂ O. Even more preferably, the draw resistance of the mouthpiece element may be greater than or equal to about 6 mm H ₂ O and less than about 10 mm H ₂ O. Preferably, the draw resistance of the mouthpiece element may be about 8 mm H ₂ O.

As described above, the mouthpiece element or the mouthpiece filter segment may be formed of a fibrous material. The mouthpiece element may be formed of a porous material. The mouthpiece element may be formed of a biodegradable material. The mouthpiece element may be formed of a cellulose material such as cellulose acetate. For example, the mouthpiece element may be formed of a bundle of cellulose acetate having a single filament denier between about 10 and about 15. For example, the mouthpiece element is formed of a relatively low density cellulose acetate tow, such as a cellulose acetate tow comprising fibers having a single filament denier of about 12.

The mouthpiece element may be formed of a polylactic acid based material. The mouthpiece element may be formed of a bioplastic material, preferably a starch based bioplastic material. The mouthpiece element may be made by injection molding or by extrusion. Bioplastic based materials are advantageous because they can provide a mouthpiece element structure that is simple and inexpensive to manufacture, with a specific and complex cross-sectional profile that may include a plurality of relatively large air flow channels extending through the mouthpiece element material that provide suitable RTD characteristics.

The mouthpiece element may be formed from a sheet of suitable material that has been curled, pleated, gathered, woven or folded into an element defining a plurality of longitudinally extending channels. Such a sheet of suitable material may be formed from paper, cardboard, a polymer (e.g., polylactic acid), or any other cellulose-based, paper-based, or bioplastic-based material. The cross-sectional profile of such a mouthpiece element may show the channels as being randomly oriented.

The mouthpiece element may be formed in any suitable manner. For example, the mouthpiece element may be formed from a bundle of longitudinally extending tubes. The longitudinally extending tubes may be formed from polylactic acid. The mouthpiece element may be formed by extrusion, molding, lamination, injection or shredding of a suitable material. Therefore, it is preferred that there is a low pressure drop (or RTD) from the upstream end of the mouthpiece element to the downstream end of the mouthpiece element.

The length of the mouthpiece element may be at least about 1.5 mm. The length of the mouthpiece element may be at least about 2 mm. The length of the mouthpiece element may be equal to or less than about 7 mm. The length of the mouthpiece element may be equal to or less than about 4 mm. For example, the length of the mouthpiece element may be between about 1.5 mm and about 7 mm. The length of the mouthpiece element may be between about 2 mm and about 4 mm.

The ratio between the length of the mouthpiece element and the length of the downstream section may be less than or equal to about 0.35. Preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be less than or equal to about 0.30. More preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be less than or equal to about 0.25.

The ratio between the length of the mouthpiece element and the length of the downstream section may be at least about 0.03. Preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be at least about 0.05. More preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be at least about 0.1.

For example, the ratio between the length of the mouthend element and the length of the downstream section is from about 0.03 to about 0.35, preferably from about 0.05 to about 0.30, more preferably from about 0.1 to about 0.25.

The ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be less than or equal to about 0.20. Preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be less than or equal to about 0.15. More preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be less than or equal to about 0.1.

The ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be at least about 0.01. Preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be at least about 0.02. More preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be at least about 0.05.

For example, the ratio between the length of the mouthend element and the overall length of the aerosol-generating article is from about 0.01 to about 0.2, preferably from about 0.02 to about 0.15, more preferably from about 0.05 to about 0.1.

In embodiments where the downstream section includes a hollow tubular element and a mouthpiece element, the ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 1.5. In other words, the length of the hollow tubular element may be at least about 150% of the length of the mouthpiece element. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 5. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 7.5.

The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be equal to or less than about 20. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be equal to or less than about 15. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be equal to or less than about 12.5.

For example, the ratio of the length of the hollow tubular element to the length of the mouthpiece element may be between about 1.5 and about 20, or between about 5 and about 15, or between about 7.5 and about 10.

The overall length of the downstream section is preferably at least about 15 mm, more preferably at least about 20 mm, and more preferably at least about 25 mm.

The overall length of the downstream section is preferably less than about 50 mm, more preferably less than about 45 mm, more preferably less than about 40 mm.

For example, the downstream section may have an overall length of between about 20 mm and about 50 mm, more preferably between about 25 mm and about 45 mm, more preferably between about 30 mm and about 40 mm.

The ratio between the total length of the downstream segment and the overall length of the aerosol-generating article may be less than or equal to about 0.80. Preferably, the ratio between the length of the downstream segment and the overall length of the aerosol-generating article may be less than or equal to about 0.75. More preferably, the ratio between the length of the downstream segment and the overall length of the aerosol-generating article may be less than or equal to about 0.70. Even more preferably, the ratio between the length of the downstream segment and the overall length of the aerosol-generating article may be less than or equal to about 0.65.

The ratio between the length of the downstream segment and the overall length of the aerosol-generating article may be at least about 0.30. Preferably, the ratio between the length of the downstream segment and the overall length of the aerosol-generating article may be at least about 0.40. More preferably, the ratio between the length of the downstream segment and the overall length of the aerosol-generating article may be at least about 0.50. Even more preferably, the ratio between the length of the downstream segment and the overall length of the aerosol-generating article may be at least about 0.60.

Preferably, the overall length of an aerosol-generating article according to the present invention is at least about 35 mm. More preferably, the overall length of an aerosol-generating article according to the present invention is at least about 40 mm. Even more preferably, the overall length of an aerosol-generating article according to the present invention is at least about 45 mm. Even more preferably, the overall length of an aerosol-generating article according to the present invention is at least about 50 mm.

The overall length of the aerosol-generating article according to the present invention is preferably less than or equal to 110 mm. More preferably, the overall length of the aerosol-generating article according to the present invention is preferably less than or equal to 100 mm. Even more preferably, the overall length of the aerosol-generating article according to the present invention is preferably less than or equal to 75 mm. Even more preferably, the overall length of the aerosol-generating article according to the present invention is preferably less than or equal to 70 mm.

For example, the overall length of the aerosol-generating article may be between about 35 mm and about 110 mm, or between about 40 mm and about 100 mm, or between about 45 mm and about 75 mm, or between about 50 mm and about 70 mm.

Preferably, the aerosol-generating article has an outer diameter of at least 4 mm. Preferably, the aerosol-generating article has an outer diameter of at least 4.5 mm. More preferably, the aerosol-generating article has an outer diameter of at least 5 mm.

Preferably, the aerosol-generating article has an outer diameter of less than or equal to about 9 mm. More preferably, the aerosol-generating article has an outer diameter of less than or equal to about 8 mm. Even more preferably, the aerosol-generating article has an outer diameter of less than or equal to about 7 mm.

For example, the aerosol-generating article may have an outer diameter of between about 4 mm and about 9 mm, or between about 4.5 mm and about 8 mm, or between about 5 mm and about 7 mm.

The outer diameter of the aerosol-generating article may be substantially constant over the entire length of the article. Alternatively, different parts of the aerosol-generating article may have different outer diameters.

In certain embodiments of the invention, one or more of the components of the aerosol-generating article is individually defined by its own wrapper.

Preferably, the aerosol-generating substrate and the downstream section are combined together in an outer wrapper such as a tipping wrapper.

Preferably, components of aerosol-generating articles according to the invention are made from biodegradable materials.

Preferably, an aerosol-generating article according to the invention as described herein is suitable for use in an electrically operated aerosol-generating system, wherein the aerosol-generating substrate of the heated aerosol-generating article is heated by an electric heat source.

The heating element of such an aerosol generating device may be of any suitable form to conduct heat. Heating of the aerosol generating substrate may be achieved from the inside, from the outside or from both the inside and the outside. The heating element may preferably be a heater blade or pin adapted to be inserted into the substrate so that the substrate is heated from the inside. The heating element may partially or completely surround the substrate and heat the substrate externally circumferentially from the outside.

The aerosol generating system may be an electrically operated aerosol generating system including an induction heating device. As in certain embodiments of the present invention described above, the induction heating device generally includes an induction source configured to be coupled to a susceptor, which may be disposed outside the aerosol generating substrate or inside the aerosol generating substrate. The induction source generates an alternating electromagnetic field that induces magnetization or eddy currents in the susceptor. The susceptor may be heated due to hysteresis losses or induced eddy currents, which heat the susceptor by ohmic or resistive heating.

An electrically operated aerosol generating system comprising an induction heating device may also comprise an aerosol generating article having an aerosol generating substrate and a susceptor in thermal proximity to the aerosol generating substrate. Typically, the susceptor is in direct contact with the aerosol generating substrate, and heat is transferred from the susceptor to the aerosol generating substrate primarily by conduction. Examples of electrically operated aerosol generating systems having an induction heating device and aerosol generating articles having a susceptor are described in WO-A1-95/27411 and WO-A1-2015/177255.

In some cases, the electrically operated aerosol generating system may include an aerosol generating article as defined above, an aerosol forming agent source and a device for vaporizing the aerosol forming agent, preferably a heating element. The aerosol forming agent source may be a refillable or replaceable reservoir located on the aerosol generating device. When the reservoir is physically separated from the aerosol generating article, the generated vapor is guided through the aerosol generating article. The vapor contacts the aerosol generating substrate, and the aerosol generating substrate releases volatile compounds, such as nicotine and flavoring agents in the granular plant material, to form an aerosol. Optionally, in order to help the volatilization of the compounds in the aerosol generating substrate, the aerosol generating system may also include a heating element to heat the aerosol generating substrate, preferably in a coordinated manner with the aerosol forming agent. However, in certain embodiments, the heating element for heating the aerosol generating article is separated from the heater for heating the aerosol forming agent.

As mentioned above, the hollow tubular substrate element of the aerosol-generating article according to the invention may advantageously be adapted such that the length substantially matches the longitudinal dimension of the heating element of the aerosol-generating system intended for heating the aerosol-generating article. This ensures that the hollow tubular substrate element is heated substantially along its entire length, so that the generation of aerosol from the aerosol-generating substrate can be maximized.

A non-exhaustive list of non-limiting examples is provided below.Any one or more features of these examples may be combined with any one or more features of another example, embodiment or aspect described herein.

EX1. An aerosol generating article, comprising: an aerosol generating substrate, the aerosol generating substrate comprising a hollow tubular substrate element, the hollow tubular substrate element having a multi-layer peripheral wall defining a longitudinal airflow channel, wherein the peripheral wall is formed by multiple overlapping layers of homogenized tobacco material; and a downstream section arranged downstream of the aerosol generating substrate.

EX2. An aerosol-generating article according to example EX1, wherein the longitudinal airflow channel has a diameter of at least 3 mm.

EX3. An aerosol-generating article according to example EX1 or EX2, wherein the hollow tubular substrate element comprises at least 2 overlapping layers of homogenized tobacco material.

EX4. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element comprises up to 10 overlapping layers of homogenized tobacco material.

EX5. An aerosol-generating article according to any of the preceding examples, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least about 0.3.

EX6. An aerosol-generating article according to any of the preceding examples, wherein the peripheral wall of the hollow tubular matrix element has a cross-sectional porosity of at least about 0.7.

EX7. An aerosol-generating article according to any of the preceding examples, wherein the peripheral wall of the hollow tubular substrate element has a density of at least 200 mg/cm3.

EX8. An aerosol-generating article according to any of the preceding examples, wherein the peripheral wall of the hollow tubular substrate element has a density of less than 1 g/cm3.

EX9. An aerosol-generating article according to any one of the preceding examples, wherein the peripheral wall of the hollow tubular substrate element provides at least 150 mg of homogenized tobacco material per centimeter length of the hollow tubular substrate.

EX10. The aerosol-generating article according to any of the preceding examples, wherein the longitudinal tensile strength of the hollow tubular substrate element is between 11 kN/m and 14 kN/m.

EX11. An aerosol-generating article according to any of the preceding examples, wherein the axial compressive strength of the hollow tubular matrix element is between 7 MPa and 9 MPa.

EX12. An aerosol-generating article according to any of the preceding examples, wherein the radial compressive strength of the hollow tubular substrate element is between 7 MPa and 9 MPa.

EX13. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element has a length of up to 40 mm.

EX14. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element has a length of at least 10 mm.

EX15. The aerosol-generating article according to any of the preceding examples, wherein a ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least 0.15.

EX16. An aerosol-generating article according to any of the preceding examples, wherein a ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is up to 0.6.

EX17. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element has an outer diameter of at least 4 mm.

EX18. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element has an outer diameter of up to 9 mm.

EX19. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element provides an unrestricted flow channel.

EX20. An aerosol-generating article according to any of the preceding examples, wherein the longitudinal airflow channels of the hollow tubular substrate element have a diameter of up to 7 mm.

EX21. An aerosol-generating article according to any of the preceding examples, wherein the ratio of the inner diameter to the outer diameter of the hollow tubular substrate element is at least 0.4.

EX22. An aerosol-generating article according to any of the preceding examples, wherein the peripheral wall has a wall thickness of at least 1 mm.

EX23. An aerosol-generating article according to any of the preceding examples, wherein the peripheral wall has a wall thickness of up to 2.25 mm.

EX24. An aerosol-generating article according to any one of the preceding examples, wherein multiple layers of homogenized tobacco material are helically wound around the longitudinal axis of the hollow tubular substrate element.

EX25. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element further comprises an adhesive for sealing adjacent layers to each other.

EX26. An aerosol-generating article according to any of the preceding examples, wherein the aerosol-generating substrate further comprises a sealing element at the upstream end of the hollow tubular substrate element, the sealing element covering the upstream end of the hollow tubular substrate element.

EX27. An aerosol-generating article according to any one of the preceding examples, wherein the homogenized tobacco material has a tobacco content of at least 40 wt.-% on a dry weight basis.

EX28. An aerosol-generating article according to any one of the preceding examples, wherein the homogenized tobacco material further comprises one or more aerosol formers.

EX29. An aerosol-generating article according to example EX28, wherein the homogenized tobacco material has an aerosol-forming agent content of between 5 wt% and 30 wt% on a dry weight basis.

EX30. The aerosol-generating article according to any one of the preceding examples, wherein the peripheral wall comprises one or more layers of a first homogenized tobacco material and one or more layers of a second homogenized tobacco material different from the first homogenized tobacco material.

EX31. An aerosol-generating article according to example EX30, wherein the first homogenized tobacco material and the second homogenized tobacco material have different tobacco contents from each other.

EX32. An aerosol-generating article according to example EX30 or EX31, wherein the first homogenized tobacco material and the second homogenized tobacco material have different aerosol former contents from each other.

EX33. An aerosol-generating article according to any one of the preceding examples, wherein the multilayer homogenized tobacco material comprises one or more cast lamina materials.

EX34. An aerosol-generating article according to example EX33, wherein the casting leaf has a porosity between 20% and 60%.

EX35. The aerosol-generating article according to any one of the preceding examples, wherein the multiple layers of homogenized tobacco material comprise one or more layers of cigarillo paper.

EX36. An aerosol-generating article according to example EX35, wherein the cigarillo paper has a porosity between 30% and 80%.

EX37. An aerosol-generating article according to any of the preceding examples, wherein the hollow tubular substrate element comprises one or more susceptor elements positioned in contact with the peripheral wall.

EX38. An aerosol-generating article according to example EX37, wherein the hollow tubular substrate element comprises one or more susceptor elements on a surface of the peripheral wall.

EX39. An aerosol-generating article according to example EX38, wherein the hollow tubular substrate element comprises a tubular susceptor element disposed on at least one surface of the peripheral wall.

EX40. An aerosol-generating article according to any of the preceding examples, wherein the downstream section comprises a hollow tubular element.

EX41. An aerosol-generating article according to example EX40, wherein the length of the hollow tubular element of the downstream section is between 12 mm and 50 mm.

EX42. An aerosol-generating article according to example EX40 or EX41, wherein the ratio between the length of the hollow tubular substrate element and the length of the hollow tubular element of the downstream section is at least 0.25.

EX43. An aerosol-generating article according to any of examples EX40 to EX42, wherein the ratio between the length of the hollow tubular substrate element and the length of the hollow tubular element of the downstream section is less than or equal to 1.25.

EX44. An aerosol-generating article according to any of examples EX40 to EX43, wherein the ratio between the length of the hollow tubular element of the downstream segment and the total length of the downstream segment is at least 0.35.

EX45. An aerosol-generating article according to any of examples EX40 to EX44, wherein the ratio between the length of the hollow tubular element of the downstream segment and the total length of the downstream segment is less than or equal to 1. EX46.

EX46. An aerosol-generating article according to any of examples EX40 to EX45, wherein a ratio between a length of the hollow tubular element of the downstream section and an overall length of the aerosol-generating article is at least 0.25.

EX47. An aerosol-generating article according to any of examples EX40 to EX46, wherein a ratio between a length of the hollow tubular element of the downstream section and an overall length of the aerosol-generating article is less than or equal to 0.8.

EX48. An aerosol-generating article according to any of examples EX40 to EX47, wherein the wall thickness of the hollow tubular element of the downstream section is at least 100 microns.

EX49. An aerosol-generating article according to any one of examples EX40 to EX48, wherein the wall thickness of the hollow tubular element of the downstream section is less than or equal to 2 mm.

EX50. An aerosol-generating article according to any one of examples EX40 to EX49, wherein the hollow tubular element of the downstream section has an inner diameter between 2 mm and 10 mm.

EX51. An aerosol-generating article according to any one of examples EX40 to EX50, wherein a ratio of an inner diameter of the hollow tubular substrate element to an inner diameter of the hollow tubular element of the downstream section is between 0.8 and 1.2.

EX52. An aerosol-generating article according to any of the preceding examples, wherein the downstream section further comprises a mouthpiece element.

EX53. An aerosol-generating article according to example EX52, wherein the mouthpiece element comprises at least one section of fibrous filter material.

EX54. An aerosol-generating article according to example EX52 or EX53, wherein the downstream section comprises a mouth-end cavity at the downstream end downstream of the mouthpiece element.

EX55. An aerosol-generating article according to any one of examples EX52 to EX54, wherein the mouthend element has a length of between 1.5 mm and 7 mm.

EX56. An aerosol-generating article according to any one of examples EX52 to EX55, wherein the ratio between the length of the mouthend element and the length of the downstream section is less than or equal to 0.35.

EX57. An aerosol-generating article according to any one of examples EX52 to EX56, wherein a ratio between a length of the mouthpiece element and an overall length of the aerosol-generating article is less than or equal to 0.20.

EX58. The aerosol-generating article according to any one of the preceding examples, wherein the RTD of the downstream section is no greater than 12 mm H ₂ O.

EX59. An aerosol-generating article according to any of the preceding examples, wherein the length of the downstream segment is between 20 mm and 50 mm.

EX60. An aerosol-generating article according to any of the preceding examples, wherein a ratio between a total length of the downstream segment and an overall length of the aerosol-generating article is less than or equal to 0.80.

EX61. An aerosol-generating article according to any of the preceding examples, wherein components of the aerosol-generating article are made of biodegradable materials.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments will be further described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic side cross-sectional view of an aerosol-generating article according to a first embodiment of the invention; and

Figure 2 shows a schematic side cross-sectional view of an aerosol-generating system comprising an aerosol-generating article and an aerosol-generating device according to a second embodiment of the invention.

Detailed ways

1 comprises an aerosol-generating substrate 12 and a downstream section 14 at a position downstream of the aerosol-generating substrate 12. Thus, the aerosol-generating article 10 extends from an upstream end or distal end 16 substantially coinciding with the upstream end of the aerosol-generating substrate 12 to a downstream end or mouth end 18 coinciding with the downstream end of the downstream section 14. The downstream section 14 comprises a hollow tubular element 20 and a mouthpiece element 50.

The aerosol-generating article 10 has an overall length of approximately 45 mm and an outer diameter of approximately 7.2 mm.

Aerosol generating substrate 12 comprises hollow tubular matrix element 40, and described hollow tubular matrix element is formed by the multilayer homogenized tobacco material of spiral winding around the longitudinal axis of hollow tubular matrix element.The homogenized tobacco material layer comprises the multilayer cast leaf alternately with the cigarillo paper layer.Hollow tubular matrix element 40 has the peripheral wall 42 formed by the overlapping layer of homogenized tobacco material.The peripheral wall 42 limits the central longitudinal airflow channel 44 extending through the hollow tubular matrix element 40.The upstream end of airflow channel 44 provides air inlet, and air can be sucked into the aerosol generating article through described air inlet during use.Hollow tubular matrix element 40 is not wrapped, and makes the homogenized tobacco material layer visible on the outer surface of aerosol generating article.

The hollow tubular matrix element 40 does not substantially affect the overall RTD of the aerosol-generating article. The RTD of the hollow tubular matrix element 40 is therefore approximately 0 mm _H20 .

The hollow tubular element 20 of the downstream section 14 is located immediately downstream of the hollow tubular matrix element 40, and the hollow tubular element 20 is longitudinally aligned with the aerosol-generating substrate 12. The upstream end of the hollow tubular element 20 abuts the downstream end of the hollow tubular matrix element 40.

The hollow tubular element 20 is provided in the form of a hollow cylindrical tube made of cellulose acetate tow. The hollow tubular element 20 defines an inner cavity 22 extending from the upstream end of the hollow tubular element 20 to the downstream end of the hollow tubular element 20. The inner cavity 22 is substantially empty, and thus a substantially non-restrictive airflow is achieved along the inner cavity 22. The hollow tubular element 20 does not substantially affect the overall RTD of the aerosol-generating article 10. The RTD of the hollow tubular element 20 is therefore approximately 0 mm _H2O .

As shown in FIG. 1 , the inner diameter of the hollow tubular element 20 of the downstream section 14 is substantially the same as the inner diameter of the hollow tubular matrix element 40 .

The mouthpiece element 50 extends from the downstream end of the hollow tubular element 20 to the downstream or mouth end 18 of the aerosol generating article 10. The mouthpiece element 50 comprises a low density cellulose acetate filter segment. The mouthpiece element 50 may be individually wrapped by a stick wrapper (not shown).

The article 10 includes a tipping wrapper 52 defining the hollow tubular member 20 and the mouthend member 50. The tipping wrapper 52 additionally overlies an upstream portion of the hollow tubular matrix member 40 so as to join the hollow tubular matrix member 40 and the downstream section 14.

The aerosol-generating article 10 is particularly suitable for use with an aerosol-generating device that includes an external heating device that heats the aerosol-generating substrate 12 from the outside. During use, the aerosol-generating article 10 is therefore preferably inserted into a heating chamber of the aerosol-generating device, with the outer surface of the hollow tubular substrate element 40 adjacent to one or more heating elements within the chamber. When a consumer draws on the article, the heating of the hollow tubular substrate element 40 generates an aerosol from the homogenized tobacco layer, which is drawn through the peripheral wall 42 and into the longitudinal airflow channels 44 of the hollow tubular substrate element 40 together with air entering the longitudinal airflow channels 44 at the upstream end. The combined air and aerosol are drawn through the aerosol-generating article 10 and delivered to the consumer from the downstream end of the aerosol-generating article 10.

FIG2 shows an aerosol generating system 100 including an aerosol generating device 102 and an aerosol generating article 110 according to a second embodiment of the present invention. The aerosol generating article 110 is similar to the aerosol generating article shown in FIG1 and described above, having a similar arrangement of components. However, the aerosol generating article 110 further includes a tubular susceptor element 160 within the longitudinal airflow channel 144 of the hollow tubular substrate element 140. The tubular susceptor element 160 is disposed on the inner surface of the longitudinal airflow channel 144.

As shown in Figure 2, the aerosol generating device 102 comprises a longitudinal heating chamber 104 for receiving an aerosol generating article 110. The heating chamber 104 has a closed distal end and an open mouth end. An air flow inlet 106 is provided at the distal end of the chamber so that air can be drawn through the aerosol generating article 110 during use. The heating chamber 104 comprises an arrangement of an inductor coil 108 for inductively heating a tubular susceptor element 160 during use.

The aerosol generating device 102 also includes a power source (not shown) for powering the inductor coil 108 and a controller (not shown) for controllably heating the aerosol generating article 110 during use when the aerosol generating article 110 is received within the device 102 .

Claims (15)

1. An aerosol generating article comprising: an aerosol-generating substrate comprising a hollow tubular substrate element having a multi-layer peripheral wall defining a longitudinal airflow channel, wherein the peripheral wall is formed from a plurality of overlapping layers of homogenized tobacco material, and wherein the longitudinal airflow channel has a diameter of at least 3 mm; and A downstream section is arranged downstream of the aerosol generating substrate. 2. An aerosol-generating article according to claim 1, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least 0.3. 3. An aerosol-generating article according to claim 1 or 2, wherein the peripheral wall comprises one or more layers of a first homogenised tobacco material and one or more layers of a second homogenised tobacco material having a different composition than the first homogenised tobacco material. 4. An aerosol-generating article according to claim 3, wherein the first homogenised tobacco material and the second homogenised tobacco material have different porosities from each other. 5. An aerosol-generating article according to any preceding claim, wherein a plurality of layers of homogenised tobacco material are helically wound about the longitudinal axis of the hollow tubular substrate element. 6. An aerosol-generating article according to any preceding claim, wherein the peripheral wall has a density of at least 200 mg/cm3. 7. An aerosol-generating article according to any preceding claim, wherein the peripheral wall provides at least 150 mg of homogenised tobacco material per centimetre of the hollow tubular substrate element. 8. An aerosol-generating article according to any preceding claim, wherein the aerosol-generating substrate further comprises a susceptor element. 9. An aerosol-generating article according to claim 8, comprising a tubular susceptor element on at least one surface of the hollow tubular substrate element. 10. An aerosol-generating article according to any preceding claim, wherein an outer surface of the hollow tubular substrate element is at least partially exposed on an outer surface of the aerosol-generating article. 11. An aerosol-generating article according to any preceding claim, wherein the hollow tubular substrate element has a length of at least 15 millimetres. 12. An aerosol-generating article according to any preceding claim, wherein the ratio of the length of the hollow tubular substrate element to the overall length of the article is at least 0.15. 13. An aerosol-generating article according to any preceding claim, wherein the downstream section comprises at least one hollow tubular element. 14. An aerosol-generating article according to claim 13, wherein the ratio between the length of the hollow tubular substrate element and the length of the hollow tubular element of the downstream section is between 0.25 and 1.25. 15. An aerosol-generating article according to claim 13 or 14, wherein the downstream section further comprises a mouthpiece element at the downstream end of the article.