WO2025141090A1

WO2025141090A1 - Plug element

Info

Publication number: WO2025141090A1
Application number: PCT/EP2024/088470
Authority: WO
Inventors: Alen Kadiric; Stefanos PAPAKYRILLOU; Margherita Montanari
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2023-12-27
Filing date: 2024-12-24
Publication date: 2025-07-03
Anticipated expiration: 2026-06-27

Abstract

A plug element (100) for use in an aerosol-generating article (300). The plug element comprises a first barrier layer (112); a second barrier layer (116); and an embossed filtration material (120). The embossed filtration material is sandwiched between the first barrier layer and the second barrier layer and comprises regenerated cellulose.

Description

PLUG ELEMENT

The present disclosure relates to a plug element. The present disclosure also relates to an aerosol-generating article comprising a plug element.

Aerosol-generating articles in which an aerosol-generating substrate comprising aerosolgenerating material, such as a tobacco-containing material, is heated rather than combusted are known in the art.

Typically, in heated aerosol-generating articles, an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate. In use, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source to the aerosol-generating substrate and are entrained in air drawn through the aerosolgenerating article. As the released compounds cool, they condense to form an aerosol that is inhaled by the user.

One known type of heated aerosol-generating article, commonly referred to as a heat-not- burn tobacco product or heated tobacco product, comprises a solid aerosol-generating substrate comprising tobacco material, which is heated to produce an inhalable aerosol.

A number of handheld aerosol-generating devices configured to heat aerosol-generating substrates of heated aerosol-generating articles are known in the art. These include electrically- operated aerosol-generating devices in which an aerosol is generated by the transfer of heat from one or more electrical heating elements of the aerosol-generating device to the aerosolgenerating substrate of the heated aerosol-generating article. Known handheld electrically operated aerosol-generating devices typically comprise a battery, control electronics and one or more electrical heating elements for heating the aerosol-generating substrate of a heated aerosolgenerating article designed specifically for use with the aerosol-generating device.

Some known electrically heated aerosol-generating devices comprise an internal heating element that is configured to be inserted into the aerosol-generating substrate of a heated aerosol-generating article. For example, WO 2013/098410 A2 discloses an aerosol-generating system comprising an aerosol-generating article and an electrically-operated aerosol-generating device comprising a heating element in the form of a blade that is inserted into the aerosolgenerating substrate of the aerosol-generating article.

Other known electrically-operated aerosol-generating devices comprise one or more external heating elements. For example, WO 2020/115151 A1 discloses an aerosol-generating system comprising an aerosol-generating article and an electrically-operated aerosol-generating device comprising an external heating element that circumscribes the periphery of the aerosolgenerating article.

Electrically-operated aerosol-generating devices comprising an inductor configured to inductively heat aerosol-generating substrates of heated aerosol-generating articles are also known. For example, WO 2015/176898 A1 discloses an aerosol-generating system comprising an aerosol-generating article comprising an elongate susceptor in thermal contact with the aerosol-generating substrate and an electrically-operated aerosol-generating device having an inductor for heating the aerosol-generating substrate. In use, the fluctuating or alternating electromagnetic field produced by the inductor induces eddy currents in the susceptor, causing the susceptor to heat up as a result of one or both of resistive losses (Joule heating) and, where the susceptor is magnetic, hysteresis loses. Heat generated in the susceptor is transferred to the aerosol-generating substrate by conduction.

Conventional aerosol-generating articles, such as filter cigarettes, typically comprise a cylindrical rod of tobacco cut filler surrounded by a paper wrapper and a cylindrical filter axially aligned, most often in an abutting end-to-end relationship, with the wrapped tobacco rod. The cylindrical filter typically comprises one or more plug elements of a fibrous filtration material, such as cellulose acetate tow, circumscribed by a paper plug wrap. Conventionally, the wrapped tobacco rod and the filter are joined by a band of tipping wrapper, normally formed of an opaque paper material that circumscribes the entire length of the filter and an adjacent portion of the wrapped tobacco rod. In known filter cigarettes, the filter is typically adapted for the removal of particulate and gaseous components of the mainstream smoke.

Many known heated aerosol-generating articles comprise one or more elements formed of a fibrous filtration material and arranged downstream of the aerosol-generating substrate. For example, aerosol-generating articles have been proposed that comprise a support element arranged immediately downstream of the aerosol-generating substrate, wherein the support element may be configured to impart structural strength to the aerosol-generating article and to resist downstream movement of the aerosol-generating substrate when the aerosol-generating substrate cooperates with the aerosol-generating device during use. Further, aerosol-generating articles have been described that comprise an aerosol-cooling element arranged downstream of the aerosol-generating substrate and configured to lower the temperature of an aerosol produced upon heating the aerosol-generating substrate prior to the aerosol reaching the mouth end of the aerosol-generating article. WO 2013/120565 A2, for example, describes an aerosol-generating article comprising an aerosol-cooling element arranged downstream of a rod of aerosolgenerating substrate. The aerosol-cooling element may be formed from a sheet material, such as for example a sheet of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), cellulose acetate (CA), a metallic foil (like aluminium foil), paper or cardboard.

After an aerosol-generating article has been smoked and discarded, it would generally be desirable for its components - and particularly for any elements formed of fibrous filtration material - to break down as quickly as possible. However, cellulose acetate, the fibrous filtration material most ordinarily used in aerosol-generating articles, is not biodegradable, and can persist in the environment for years. As a result, used cigarette filters formed from cellulose acetate have a tendency to accumulate in the environment, and are among the most commonly retrieved plastic items in beach clean-up activities. Therefore, it would be desirable to provide a more sustainable alternative to cellulose acetate for producing aerosol-generating article components and in particular, filter or mouthpiece components.

To tackle the environmental impact caused by post-consumption waste of articles containing non-biodegradable plastic, discarded directly into the environment, certain jurisdictions are introducing legislations banning single-use plastic products (SLIPs). The term SLIPs denotes products made wholly or partly from plastic and that are typically intended to be used just once or for a short period of time before being disposed of. Accordingly, it would be generally desirable to replace single-use plastics in aerosol-generating articles with natural, biodegradable alternatives.

A wide variety of alternative materials have in fact already been proposed for use as filtration materials for aerosol-generating articles. However, in many cases, such alternative filtration materials have been found to be unable to provide an acceptable filtration efficiency and smoking experience for the consumer.

For example, filters made of cellulose pulp or paper material have been known for almost a century, as evidenced by GB 433048 A. Several processes for manufacturing paper filters have been disclosed over the years, such as the ones described in US 3238852 A. However, consumers have often reported that paper filters have an undesirable effect on the taste of the smoke or aerosol. This so-called “paper taste” has been described as being associated with a harsher, drier sensation compared to that provided by a known smoking article comprising a filter formed of cellulose acetate.

In other cases, such alternative filtration materials have been found to be lacking from a firmness and processability viewpoint. Furthermore, in many cases dispersible and degradable materials have been found to be unsuitable for use in the existing manufacturing processes, and would require too significant a modification of the existing methods and equipment to make their use commercially feasible.

Thus, it would be desirable to provide an aerosol-generating article comprising a component that is at least partially formed of a filtration material having increased biodegradability, but which provides a filtration efficiency that is comparable to that of a cellulose acetate tow. In particular, it would be desirable for the component to be formed of a biodegradable filtration material that can still effectively reduce or remove undesirable compounds from the aerosol generated from the substrate (for example, phenols). The present disclosure relates to a plug element. The present disclosure also relates to an aerosol-generating article comprising a plug element.

According to an aspect of the invention there is provided a plug element, for example a plug element for use in an aerosol-generating article. The plug element may include a first barrier layer; a second barrier layer; and a filtration material. The filtration material may be sandwiched between the first barrier layer and the second barrier layer. Each of the first barrier layer, the second barrier layer and the filtration material may include a cellulosic material. The filtration material may include regenerated cellulose.

According to another aspect of the invention there is provided a plug element for use in an aerosol-generating article. The plug element includes a first barrier layer; a second barrier layer; and a filtration material; wherein the filtration material is sandwiched between the first barrier layer and the second barrier layer; and wherein the filtration material comprises regenerated cellulose.

Advantageously, the plug element provides structure to aerosol-generating articles, can generate nucleation in the aerosol formed and can also restrict the movement of tobacco particles and/or susceptor elements within the aerosol-generating article.

The first and second barrier layers may also prevent migration and/or absorption of oil or aerosol formers on the layers of the aerosol-generating article.

The first barrier layer may form an outer surface of the plug element. The first barrier layer may include a sheet, a film or a coating of a cellulosic or a cellulose-based material. The cellulosic or cellulose-based material may be a processed paper material, for example a processed paper material selected from the group consisting of glassine paper, parchment paper and natural greaseproof paper.

The first barrier layer may have a grammage of between approximately 20 grams per squared metre and approximately 30 grams per squared metre. The grammage of the first barrier layer may be, for example between approximately 23 grams per squared metre and approximately 28 grams per squared metre.

The first barrier layer may have a tensile breaking strength of between approximately 15 Newtons per 15 millimetres and approximately 20 Newtons per 15 millimetres.

The first barrier layer may have a permeability of between approximately 8,000 Coresta units and approximately 15,000 Coresta units. The permeability of the first barrier layer may be, for example, between approximately 9,500 Coresta units and approximately 14,500 Coresta units.

The first barrier layer may have a thickness of between approximately 50 micrometresand approximately 85 micrometres. The thickness of the first barrier layer may be, for example, between approximately 60 micrometres and approximately 80 micrometres.

The second barrier layer may form an inner surface of the plug element. The second barrier layer may define a hollow core of the plug element. The second barrier layer may include a sheet, a film or a coating. The sheet, the film or the coating of the second barrier layer may include a cellulose-based material. The cellulose-based material may be, for example, a processed paper, cardboard or extruded starch material.

The second barrier layer may have a grammage of between approximately 80 grams per squared metre and approximately 115 grams per squared metre The grammage of the second barrier layer may be, for example between approximately 90 grams per squared metre and approximately 105 grams per squared metre.

The second barrier layer may have a thickness of between approximately 100 micrometres and approximately 160 micrometres. The thickness of the second barrier layer may be, for example, between approximately 105 micrometres and approximately 145 micrometres.

The filtration material may be a crimped filtration material.

The filtration material may be an embossed filtration material.

According to an aspect of the invention there is provided a plug element for use in an aerosol-generating article, the plug element including: a first barrier layer; a second barrier layer; and an embossed filtration material; wherein the embossed filtration material is sandwiched between the first barrier layer and the second barrier layer.

The filtration material, for example the embossed filtration material, may include at least one layer of regenerated cellulose material. The regenerated cellulose material may be free of cellulose acetate. The regenerated cellulose material may include regenerated cellulose fibres. The regenerated cellulose fibres may be arranged substantially parallel to a longitudinal axis of the at least one layer of regenerated cellulose material. The regenerated cellulose fibres may be selected from one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres.

The filtration material, for example the embossed filtration material, may include at least one layer of a blend of cellulose and regenerated cellulose. The blend of cellulose and regenerated cellulose may be free of cellulose acetate. The regenerated cellulose may include regenerated cellulose fibres. The regenerated cellulose fibres may be arranged substantially parallel to a longitudinal axis of the blend of cellulose and regenerated cellulose material. The regenerated cellulose fibres may be selected from one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres.

The plug element may have a length of between approximately 5 millimetres and approximately 21 millimetres. The length of the plug element may be, for example, between approximately 7 millimetres and approximately 15 millimetres.

The plug element may have a diameter of between approximately 3 millimetres and approximately 10 millimetres. The plug element may have a wall thickness of between approximately 0.5 millimetres and approximately 4 millimetres.

An adhesive may be provided between the first barrier layer and the filtration material.

The or another adhesive may be provided between the filtration material and the second barrier layer.

The or each adhesive may be a natural adhesive, for example a natural adhesive including starch.

The plug element may be a downstream element for use in an aerosol-generating article. The plug element may be one or more of a filter element, a support element, an aerosol-cooling element and a mouthpiece filter element.

According to another aspect of the invention there is provided an aerosol-generating article. The aerosol-generating article includes an aerosol-generating substrate and a plug element according to the preceding aspects of the invention. The plug element may be positioned downstream of the aerosol-generating substrate.

As used herein with reference to the invention, the term “aerosol-generating article” is used to describe an article comprising an aerosol-generating substrate that is heated to generate an inhalable aerosol for delivery to a user.

As used herein with reference to the invention, the term “aerosol-generating substrate” is used to describe a substrate comprising aerosol-generating material that is capable of releasing upon heating volatile compounds that can generate an aerosol.

As used herein with reference to the invention, the term “aerosol” is used to describe a dispersion of solid particles, or liquid droplets, or a combination of solid particles and liquid droplets, in a gas. The aerosol may be visible or invisible. The aerosol may include vapours of substances that are ordinarily liquid or solid at room temperature as well as solid particles, or liquid droplets, or a combination of solid particles and liquid droplets.

As used herein with reference to the invention, the term “aerosol-generating device” is used to describe a device that interacts with the aerosol-generating substrate of the aerosolgenerating article to generate an aerosol.

Aerosol-generating articles according to the invention have a proximal end through which, in use, an aerosol exits the aerosol-generating article for delivery to a user. The proximal end of the aerosol-generating article may also be referred to as the downstream end or the mouth end of the aerosol-generating article. In use, a user draws directly or indirectly on the proximal end of the aerosol-generating article in order to inhale an aerosol generated by the aerosol-generating article. Aerosol-generating articles according to the invention have a distal end. The distal end is opposite the proximal end. The distal end of the aerosol-generating article may also be referred to as the upstream end of the aerosol-generating article.

Components of aerosol-generating articles according to the invention may be described as being upstream or downstream of one another based on their relative positions between the proximal end of the aerosol-generating article and the distal end of the aerosol-generating article.

As used herein with reference to the invention, the term “longitudinal” is used to describe the direction between the upstream end and the downstream end of the aerosol-generating article. During use, air is drawn through the aerosol-generating article in the longitudinal direction.

As used herein with reference to the invention, the term “length” is used to describe the maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the longitudinal direction.

As used herein with reference to the invention, the term "hollow tubular element" is used to denote a generally cylindrical element having a lumen along a longitudinal axis thereof. The tubular portion may have a substantially circular, oval or elliptical cross-section. The lumen may have a substantially circular, oval or elliptical cross-section. In particular, the term "hollow tubular element" is used to denote an element defining at least one airflow conduit establishing an uninterrupted fluid communication between an upstream end of the hollow tubular element and a downstream end of the tubular element.

The plug element of the downstream element of an aerosol-generating article in accordance with the present invention is air-permeable. As used herein, the term “air-permeable” is used to describe an entity which allows air to pass through it. The term “air-permeable” also encompasses a volume characteristic of a suitable material, either in relation to all or part of its volume; for example, a material having a porosity in all or part of the volume of the material.

In more detail, the term “air-permeable”, as used herein with reference to the plug element of an aerosol-generating article according to the present invention, denotes a plug element that is not blocked, plugged or sealed in a way to block air from passing through the air-permeable plug element.

The air-permeable plug element may be configured so as to enable flow along a desired airflow direction. For example, an air-permeable plug element may be configured so as to enable flow from a first end of the air-permeable plug element to a second end of the air-permeable plug element longitudinally opposite the first end of the air-permeable plug element.

To enable flow along a desired airflow direction, the air-permeable plug element may comprise one or more airflow channels extending through the air-permeable plug element. For example, the air-permeable plug element may comprise one or more airflow channels extending from a first end of the air-permeable plug element to a second end of the air-permeable plug element opposite the first end of the air-permeable plug element.

The one or more airflow channels of the air-permeable plug element may be arranged within the air-permeable body portion in regular and orderly fashion. For example, the air- permeable plug element may define a plurality of substantially longitudinal airflow channels extending parallel to each other.

The plug element will typically be substantially cylindrical, and so a transverse cross- sectional of the plug element will be substantially circular. However, more generally it will be possible to identify a longitudinal axis of the plug element and a transverse cross-section of the plug element will be in a plane substantially perpendicular to said longitudinal axis.

For the purposes of the invention, the term “paper material” generally denotes a web of cellulosic fibres in sheet form. As used herein with reference to the invention, the term “sheet” is used to describe a laminar element having a width and a length substantially greater than a thickness thereof. The sheet may have a thickness ranging from 0.03 to 2 millimetres and a basis weight of from 10 grams per square metre to 200 grams per square metre. The term “paper” is typically used to denote one such web of cellulosic fibres in sheet form, wherein the sheet has a thickness ranging from 0.03 to 0.20 millimetres.

To form the web, an aqueous slurry of pulp fibres is drained through a sieve-like screen, so that a mat of randomly interwoven fibres is laid down. Water is further removed from this mat by pressing, optionally assisted by suction or vacuum, or by heating, or both. Once the drying process is complete, a generally flat and uniform sheet of paper material is obtained.

The term “pulp” is used to denote a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops, waste paper, or rags. Lignocellulose is composed primarily of cellulose, hemicellulose and lignin.

The term “cellulose” denotes an organic compound with the formula (CeHwOs A polysaccharide consisting of a linear chain of several hundreds to many thousands of D-glucose units joined by a glycosidic-bond, cellulose is a structural component of the primary cell wall of green plants and many algae.

The term “hemicellulose” identifies a groups of polysaccharides typically present with cellulose in almost all terrestrial plant cell walls. The hemicellulose polysaccharides are shorter than cellulose and typically branched. From a chemical viewpoint, while cellulose is derived exclusively from glucose, hemicellulose polysaccharides include both five-carbon sugars (xylose and arabinose) and six-carbon sugars (mannose and galactose on top of glucose). Additionally, acidified forms of sugars - such as glucuronic acid and galacturonic acid - may be found in hemicellulose. The term “lignin” identifies a group of highly heterogeneous polymers derived from a few Precursor lignols. Its heterogeneity arises from the diversity and variable degree of crosslinking between these lignols. For example, the relative amounts of the precursor lignols generally varies depending on the plant source. The lignin polymers typically form key structural materials in the support tissues of plant, and especially in the cell walls of wood and bark, and are also found in red algae. Lignin fills gaps in the cell walls between cellulose, hemicellulose and pectin components, lending rigidity by virtue of the cross-linking between the lignol molecules.

Lignin is understood to hinder the formation of hydrogen bonds between cellulose fibres. Therefore, some pulping processes are designed to remove as much lignin as possible, as this is understood to provide stronger paper by facilitating inter-fibre bonding. Other pulping processes aim instead at separating the fibres. Pulp intended for use in fine papers typically undergoes a papermaking process aiming at both removing the lignin and separating the fibres.

However, irrespective of the specific pulping process used, the lignin gets more resistant to removal as the pulping proceeds, while the cellulose fibres become more vulnerable to the chemicals used or to the mechanical pulping or both. Therefore, at the end of the papermaking process, some lignin is ordinarily present in all paper materials, as the complete removal of lignin would in all likelihood be accompanied by excessive cellulose loss or by some less than desirable degradation of the mechanical properties of the cellulose fibres.

Glassine paper, parchment paper and natural greaseproof paper (such as Nordic Paper Perga® or Superperga®) are processed paper materials with a comparatively high density, typically close to or higher than 1 gram/cubic centimetre. Preferred values of density for the processed paper material used in the plug of aerosol-generating articles in accordance with the present invention will be discussed in more detail below.

To achieve such a comparatively high density values falling within these ranges, the sheet of paper material obtained from pressing and drying the mat of randomly interwoven fibres, as described above, is then typically thinned, and the surface of the sheet of paper material is typically smoothed by pressing the sheet of paper material between metal cylinders or rollers, which are also referred to as calenders. This operation, denoted as “calendering”, is typically the last step of the papermaking process before the paper material is cut to standard sizes. Calendering may be carried out at high temperature, optionally in presence of plasticisers or mineral fillers (for example, calcium carbonate).

As used herein with reference to the present invention, the term “glassine paper” is used to denote a paper material that has been subjected to a supercalendering process. In fact, glassine paper is often also referred to as “supercalendered paper”.

To make glassine paper, after the sheet of paper material has been thinned by the calendering process, the sheet of paper is fed through an additional set of calenders called “supercalender”. The supercalender consists of several cylinders alternating between polished metal and soft resilient surfaces (also called “nips”), typically provided as fibre-covered cylinders. The supercalender runs at high speed and applies pressure, heat, and friction to the sheet of paper material. Once compressed, the fibres defining the soft resilient surfaces struggle to return to their original dimensions, and thus they buff the sheet of paper material passing through the nips.

The force generated by each progressive nip is understood to polish both surfaces of the sheet of paper material. Without wishing to be bound by theory, this is understood to be due to the supercalendering process breaking down the capillaries of the cellulose fibres at a cellular level. This imparts the sheet of paper material undergoing supercalendering a highly closed surface, along with improved density and very low porosity. As a result, glassine paper is typically more resistant to grease and moisture than non-supercalendered paper materials. Additionally, both sides of a sheet of glassine paper tend to have a smooth and glossy finish.

Further details about how glassine paper can be manufactured can be found in US 2792765 A.

As used herein with reference to the present invention, the term “parchment paper” is used to denote a paper material which has been treated with sulphuric acid to impart the paper material enhanced non-stick or release properties. To make parchment paper, the sheet of paper pulp is run through a bath of sulphuric acid, which has the effect of partially dissolving and fusing together the pulp fibres. Without wishing to be bound by theory, this is understood to form a sulphurised, cross-linked structure, which displays comparatively high density in combination with good heat resistance, grease resistance, water resistance, and generally low surface energy. At the end of its manufacturing process, parchment paper - which is also at times referred to as “vegetable parchment” - has an appearance similar to that of parchment.

Further details about how parchment paper can be manufactured can be found in US 1334843 A.

The term “greaseproof paper” is commonly used to refer to a refined paper material that has been made impermeable to oil or grease. These properties make greaseproof paper particularly suitable for use in cooking and food packaging. As used herein with reference to the present invention, the term “natural greaseproof paper” is used to denote a greaseproof paper obtained by subjecting the paper material to a beating process, whereby a great number of bonding sites are formed on each fibre, which in turn enhances the overall density of the paper material. Without wishing to be bound by theory, it is understood that this process imparts the paper material a closed surface structure with a rather small number of large surface pores. Thus, natural greaseproof paper combines comparatively high density with a very low porosity. For example, Scandinavian company Nordic Paper offers for sale natural greaseproof paper whose barrier properties make it an alternative to paper materials treated with fluorochemicals.

As used herein, the term “phenols” refers to a class of chemical compounds consisting of a hydroxyl group ( — OH) bonded directly to an aromatic hydrocarbon group. The phenol group includes phenol, catechol, m+P cresols, and o-cresol.

As used herein, with reference to the present invention, the term “additive for reducing phenols” is used to denote any additive, which, when added to a mouthpiece of an aerosolgenerating article, is capable of reducing the level of at least one of phenol, catechol, m+P cresols, and o-cresol in the smoke or aerosol, when subjected to a standard smoking test.

The present invention provides an improved aerosol-generating article comprising at least one downstream element, the downstream element comprising a plug element including a filtration material including regenerated cellulose. Aerosol-generating articles according to the present invention can therefore advantageously be formed of more sustainable materials, containing a reduced or zero level of single use plastics. In particular, aerosol-generating articles according to the invention use one of the selected processed paper materials listed above in place of other more conventional materials, such as cellulose acetate fibres, to form elements such as filtration elements, thereby significantly improving the biodegradability of the aerosol-generating article.

First of all, using a paper material, which comprises randomly oriented cellulose fibres, advantageously facilitates degradation of the plug element. This is because the randomly oriented fibres can more easily disperse after the plug element has been discarded, particularly when compared with the substantially continuous filaments of traditional cellulose acetate tow filters. Increased dispersion of the fibres increases the exposure of the individual fibres to the environment, thus increasing the rate at which the plug element degrades.

Subjecting the paper material to a supercalendering process (as in the case of glassine paper) or to a high degree of beating (as in the case of natural greaseproof paper) or to sulphuric acid treatment (as in the case of parchment paper) has advantageously been found to significantly lessen the impact of the filtration material of the downstream element on the taste of the smoke or aerosol provided to the consumer during of the aerosol-generating article.

In the plug element, the processed paper material is typically in the form of a sheet, which is gathered or otherwise processed to be formed into rod-shape. As used herein with reference to the invention, the term “gathered” denotes that a sheet is compressed or constricted substantially transversely relative to a longitudinal axis of the plug element.

Alternatively, the web or sheet of processed paper material may be wound to form a substantially cylindrical hollow tubular element. By varying the number of turns or convolutions, one may adjust the thickness of the hollow tubular element. Prior to being formed into a rod or hollow tubular element, the web or sheet of processed paper material may be textured. Texturing of the web or sheet of paper material may advantageously facilitate gathering of the sheet into a rod.

As used herein, the term “textured sheet” denotes a sheet that has been crimped, embossed, debossed, perforated or otherwise deformed. Textured sheets of processed paper material may therefore comprise a plurality of spaced-apart indentations, protrusions, perforations or a combination thereof.

As used herein, the term “crimped sheet” is intended to be synonymous with the term “creped sheet” and denotes a sheet having a plurality of substantially parallel ridges or corrugations. Preferably, in a plug element formed by gathering a crimped sheet of processed paper material, the crimped sheet has a plurality of ridges or corrugations substantially parallel to a cylindrical axis of the plug element. This advantageously facilitates gathering of the crimped sheet of processed paper material to form a rod. However, it will be appreciated that crimped sheets of processed paper material for use in plug elements of aerosol-generating articles as described herein may alternatively or in addition have a plurality of substantially parallel ridges or corrugations disposed at an acute or obtuse angle to the longitudinal axis of the plug element. In general, the provision of the plurality of ridges or corrugations increases a surface area of a plug element formed from one such crimped sheet, which may enhance the filtration efficiency of the plug draw resistance by facilitating contact between the aerosol or smoke flowing through the plug element and the additive coating. Crimping sheets of processed paper may also improve the structural integrity of the paper material and thus a rod formed from the crimped sheet.

As used herein, the term “embossed sheet” denotes a sheet having raised or recessed designs or patterns that have been pressed into the surface of the processed paper material. Advantageously, the embossed patterns increase the surface of area of the paper material and thus allow for better filtration from a plug element formed from an embossed sheet.

Embossing adds rigidity to processed paper, and thus helps the formed rod to maintain its shape and structure during use. This is important in maintaining consistent performance of the plug element formed from an embossed sheet.

Patterns created by embossing may help regulate airflow through a filter formed from an embossed sheet, thereby ensuring a more controlled and efficient filtration process. This enables the provision of a stable resistance to draw (RTD) and a stable RTD co-efficient of variation (CV).

Unless otherwise stated, the RTD of the aerosol-generating article or a component of the aerosol-generating article is measured in accordance with ISO 6565-2015 at a volumetric flow rate of about 17.5 millilitres per second at the proximal end or downstream end of the aerosolgenerating article or the component thereof at a temperature of about 22 degrees Celsius, a pressure of about 101 kPa (about 760 Torr) and a relative humidity of about 60%. In certain embodiments, sheets of processed paper material for use in forming plug elements as described herein may be substantially evenly textured over substantially their entire surface. For example, crimped sheets of processed paper material for use in forming plug elements as described herein may comprise a plurality of substantially parallel ridges or corrugations that are substantially evenly spaced-apart across the width of the sheet. In other examples, embossed sheets of processed paper may be used to form plug elements as described herein. The raised or recessed designs or patterns that are pressed into the surface of the embossed sheets of processed paper material may be selected to impact one or more characteristics of the filter's performance.

A diamond pattern, for example, may be provided to increase the surface area and provides enhanced structural integrity, making it ideal for high-efficiency filtration.

A wave pattern may be provided, in examples, to control airflow and/or to enhance the absorption capacity of the filter. Embossed sheets of processed paper having a wave pattern may be used in applications for which a smooth airflow is important.

Known for its strength and durability, an embossed honeycomb pattern enables the provision of a processed paper material having a large surface area for filtration, which is effective in capturing fine particles.

An embossed grid pattern provides both structural support and increased surface area, and thus can be used in various filtration applications.

Custom embossing patterns may also be used for branding purposes, for example to imprint logos or other designs onto the processed paper material. Such embossed textures may also enhance the filtration properties of the material.

Gathering or winding the sheet of processed paper material, for example the embossed processed paper material, to form the plug element has the benefit that by adjusting the number of convolutions or how tight the sheet is gathered it is possible to ensure that the plug element displays the required resistance to mechanical deformation, such that in the aerosol-generating article the plug element can withstand being grasped by the consumer during smoking.

The grammage of the materials used in the plug element may be selected based on a balance between the ability of the plug element to withstand a compressive load during use, and the need to preserve a certain pliability of the sheet of processed paper material to be able to form it into a desired shape. Further, the grammage of the processed paper material may be selected such that the plug element is able to resist deformation during storage, transportation and use of the aerosol-generating article.

The thickness of the first and second barrier layers may be selected to ensure a certain pliability of the materials, so as to enable one or more of crimping, gathering, pleating, and folding of the materials. Preferably, the cellulosic filtration material, for example the embossed cellulosic filtration material, does not include cellulose acetate fibres or any other fibres formed of non-biodegradable polymers.

The regenerated cellulose material may be free of cellulose acetate. The porous fibrous material may comprise regenerated cellulose fibres. The porous fibrous material may be made of regenerated cellulose fibres. The regenerated cellulose fibers may be arranged substantially parallel to a longitudinal axis of the filtration material. A longitudinal axis of the regenerated cellulose fibers may be arranged substantially parallel to a longitudinal axis of the filtration material.

Regenerated cellulose fibers may be derived from tobacco. Regenerated cellulose fibers may be derived from tobacco plants stems. As tobacco plant stems exist largely as waste of processing tobacco plants, regenerated cellulose fibers derived from tobacco plant stems may be a sustainable source of fibers. Regenerated cellulose fibers may be obtained from bamboo. Regenerated cellulose fibers may be obtained from bamboo culms. As sustainable bamboo agriculture exists at large scale, and bamboo may be a sustainable source of fibers. As waste of bamboo processing materials may be used to obtain regenerated cellulosic fibers, bamboo may be a sustainable source of regenerated cellulose fibers. The regenerated cellulose material may be derived from one or more of tobacco plant stems and bamboo culms.

The regenerated cellulose fibers may have a uniform length. A length of the regenerated cellulose fibers may be homogenised. A length of the regenerated cellulose fibers may be homogenised using continuous spinning in the regenerating technology. The cellulosic material from which the regenerated cellulose fibers are derived may be obtained from recycling materials.

Homogenization of the length of the regenerated cellulose fibers may be achieved by preparing and dissolving intermediate compounds, such as sodium xanthate or acetate derivatives, along with the regeneration of the fibers. Derivatization of the cellulose fibers may improve the solubility of the the fibers in a solvent. The solvent may be aqueous or non-aqueous. The cellulose structure may be transformed depending on the type of solvent, treatment conditions and the type of fibers to be obtained.

The porous fibrous material may be regenerated cellulose material tow. The porous fibrous material may be regenerated cellulose fiber tow. The porous fibrous material may comprise a bundles of regenerated cellulose fibers.

The fibers may be regenerated cellulose fibers selected from one or more of viscose fibers, rayon fibers, modal fibers, tencel fibers, and lyocell fibers, and any combination thereof. The fibers may be preferably selected from tencel fibers and lyocell fibers. Tencel fibers and lyocell fibers may be biodegradable. In some embodiments, the aerosol-generating article is formed essentially of an aerosolgenerating substrate and of a downstream element as described above provided in abutting arrangement with the rod of aerosol-generating substrate. For example, the aerosol-generating substrate may be in the form of a cylindrical rod of shredded tobacco material circumscribed by a wrapper, and the downstream element may be attached to the wrapped rod by a band of tipping paper so as to form a mouthpiece of the aerosol-generating article.

In other embodiments, the aerosol-generating article comprises one or more additional elements also provided downstream of the aerosol-generating substrate and in axial alignment with the aerosol-generating substrate. The downstream element comprising the plug element and any further element provided downstream of the aerosol-generating substrate and in axial alignment with the aerosol-generating substrate form a downstream section of the aerosolgenerating article.

In some preferred embodiments, the downstream element comprising the plug element is a mouthpiece element.

The aerosol-generating article may comprise a mouthpiece at the downstream end or mouth end or proximal end of the aerosol-generating article, the mouthpiece consisting of the plug element alone.

Alternatively, the aerosol-generating article may comprise a mouthpiece at the downstream end or mouth end or proximal end of the aerosol-generating article, the mouthpiece including the plug element and one or more further elements axially aligned in an abutting end to end relationship with each other. The plug element and the one or more further elements may be formed of the same material. Alternatively, the one or more further elements may be formed of a material other than the material of the plug element.

Parameters or characteristics described herein in relation to the plug element used as the sole component of the mouthpiece may equally be applied to a plug element used as one of multiple components of the mouthpiece.

Advantageously, aerosol-generating articles according to the present invention wherein the downstream element is a mouthpiece element provide an acceptable visual impact and tactile experience for the consumer, thanks to the density and firmness of the plug element. Additionally, in aerosol-generating articles according to the present invention wherein the downstream element is a mouthpiece element, the cellulosic filtration material is capable of efficiently cooling a smoke or aerosol generated from the substrate, with little to no impact on the taste perceived by the consumer during use of the aerosol-generating article. As such, aerosol-generating articles according to the present invention wherein the plug element is a mouthpiece element provide a much more sustainable alternative to aerosol-generating articles comprising a cellulose acetate filter segment as a mouthpiece filter segment. The mouthpiece element may have a low particulate phase filtration efficiency or even substantially no particulate phase filtration efficiency. Whilst capable of preventing substrate material from the aerosol-generating substrate potentially reaching the mouth of the consumer during use, a mouthpiece element having low particulate phase filtration efficiency has a reduced impact on delivery of aerosol species to the consumer. This is especially advantageous in aerosol-generating article wherein the aerosol-generating substrate is heated as opposed to being combusted.

In some embodiments, the plug element may be an additional element provided downstream of the aerosol-generating substrate other than a mouthpiece element. That is, the aerosol-generating article comprises a mouthpiece and the plug element is provided between the aerosol-generating substrate and a mouthpiece of the aerosol-generating article.

For example, the downstream element may be a support element provided immediately downstream of the aerosol-generating substrate, preferably adjacent to the aerosol-generating substrate. One such support element is adapted to impart structural strength to the aerosolgenerating article. The support element is advantageously configured to resist downstream movement of the aerosol-generating substrate during insertion of the heating element of the aerosol-generating device into the aerosol-generating.

In some preferred embodiments, the downstream element comprising the plug element may form part of an aerosol-cooling element provided downstream of the aerosol-generating substrate, the aerosol-cooling element being adapted to facilitate cooling of the aerosol generated during use of the aerosol-generating article prior to reaching the downstream end of the aerosolgenerating article.

In some embodiments, the downstream section of the aerosol-generating article may comprise, in sequential order, a support element, an aerosol-cooling element, and a mouthpiece. Preferably, one or more of the support element, aerosol-cooling element, and mouthpiece are in the form of a plug element as described above.

The aerosol-generating article may be a combustible smoking article. A combustible smoking article typically comprises a cylindrical rod of tobacco cut filler surrounded by a paper wrapper and a cylindrical filter axially aligned, most often in an abutting end-to-end relationship, with the wrapped tobacco rod. The cylindrical filter typically comprises one or more plug elements of a fibrous filtration material circumscribed by a paper plug wrap. The wrapped tobacco rod and the filter are typically joined by a band of tipping wrapper, that circumscribes the entire length of the filter and an adjacent portion of the wrapped tobacco rod. In combustible smoking articles according to the present invention, the cylindrical filter comprises a downstream element comprising a plug element having the characteristics described above. The aerosol-generating article may be an aerosol-generating article for generating an aerosol upon heating (a heated aerosol-generating article). A heated aerosol-generating article typically comprises a cylindrical rod of aerosol-generating substrate surrounded by a paper wrapper and a downstream section downstream of the rod of aerosol-generating substrate. The downstream section typically comprises at least one hollow tubular element immediately downstream of the rod of aerosol-generating substrate and a mouthpiece.

The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

Example EX1. A plug element for use in an aerosol-generating article, the plug element comprising: a first barrier layer; a second barrier layer; and a filtration material; wherein the filtration material is sandwiched between the first barrier layer and the second barrier layer and comprises regenerated cellulose.

Example EX2. The plug element of example EX1 , wherein the first barrier layer forms an outer surface of the plug element.

Example EX3. The plug element of example EX1 or EX2, wherein the first barrier layer comprises a sheet, a film or a coating.

Example EX4. The plug element of example EX3, wherein the sheet, the film or the coating comprises a cellulose-based material.

Example EX5. The plug element of example EX4, wherein the cellulose-based material is a processed paper material selected from the group consisting of glassine paper, parchment paper and natural greaseproof paper.

Example EX6. The plug element of any one of examples EX1 to EX5, wherein the first barrier layer has a grammage of at least 20 grams per squared metre.

Example EX7. The plug element of example EX6, wherein the grammage of the first barrier layer is at least 23 grams per squared metre.

Example EX8. The plug element of example EX6 or EX7, wherein the grammage of the first barrier layer is up to 30 grams per squared metre.

Example EX9. The plug element of any one of examples EX6 to EX8, wherein the grammage of the first barrier layer is up to 28 grams per squared metre.

Example EX10. The plug element of any one of examples EX1 to EX9, wherein the first barrier layer has a tensile breaking strength of at least 15 Newtons per 15 millimetres.

Example EX11. The plug element of example EX10, wherein the tensile breaking strength of the first barrier layer is at least 20 Newtons per 15 millimetres.

Example EX12. The plug element of any one of examples EX1 to EX11 , wherein the first barrier layer has a permeability of at least 8,000 Coresta units. Example EX13. The plug element of example EX12, wherein the permeability of the first barrier layer is at least 9,500 Coresta units.

Example EX14. The plug element of example EX12 or EX13, wherein the permeability of the first barrier layer is up to 15,000 Coresta units.

Example EX15. The plug element of any one of examples EX12 to EX14, wherein the permeability of the first barrier layer is up to 14,500 Coresta units.

Example EX16. The plug element of any one of examples EX1 to EX15, wherein the first barrier layer has a thickness of at least 50 micrometres.

Example EX17. The plug element of example EX16, wherein the thickness of the first barrier layer is at least 60 micrometres.

Example EX18. The plug element of example EX16 or EX17, wherein the thickness of the first barrier layer is up to 85 micrometres.

Example EX19. The plug element of any one of examples EX16 to EX18, wherein the thickness of the first barrier layer is up to 80 micrometres.

Example EX20. The plug element of any one of examples EX1 to EX19, wherein the second barrier layer forms an inner surface of the plug element.

Example EX21. The plug element of example EX20, wherein the second barrier layer defines a hollow core of the plug element.

Example EX22. The plug element of any one of examples EX1 to EX21 , wherein the second barrier layer comprises a sheet, a film or a coating.

Example EX23. The plug element of example EX22, wherein the sheet, the film or the coating comprises a cellulose-based material.

Example EX24. The plug element of example EX23, wherein the cellulose-based material is a processed paper, cardboard or extruded starch material.

Example EX25. The plug element of any one of examples EX1 to EX24, wherein the second barrier layer has a grammage of at least 80 grams per squared metre.

Example EX26. The plug element of example EX25, wherein the grammage of the second barrier layer is at least 90 grams per squared metre.

Example EX27. The plug element of example EX25 or EX26, wherein the grammage of the second barrier layer is up to 115 grams per squared metre.

Example EX28. The plug element of any one of examples EX25 to EX27, wherein the grammage of the second barrier layer is up to 105 grams per squared metre.

Example EX29. The plug element of any one of examples EX1 to EX28, wherein the second barrier layer has a thickness of at least 100 micrometres.

Example EX30. The plug element of example EX29, wherein the thickness of the second barrier layer is at least 105 micrometres. Example EX31. The plug element of example EX29 or EX30, wherein the thickness of the second barrier layer is up to 160 micrometres.

Example EX32. The plug element of any one of examples EX29 to EX31, wherein the thickness of the second barrier layer is up to 145 micrometres.

Example EX33. The plug element of any one of examples EX1 to EX32, wherein the filtration material is a crimped filtration material.

Example EX34. The plug element of any one of examples EX1 to EX33, wherein the filtration material is an embossed filtration material.

Example EX35. The plug element of any one of examples EX1 to EX34, wherein the filtration material, for example the crimped filtration material or the embossed filtration material, comprises at least one layer of regenerated cellulose material.

Example EX36. The plug element of example EX35, wherein the regenerated cellulose material is free of cellulose acetate.

Example EX37. The plug element of example EX35 or EX36, wherein the regenerated cellulose material comprises regenerated cellulose fibres.

Example EX38. The plug element of example EX37, wherein the regenerated cellulose fibres are arranged substantially parallel to a longitudinal axis of the at least one layer of regenerated cellulose material.

Example EX39. The plug element of EX37 or EX38, wherein the regenerated cellulose fibres are selected from one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres.

Example EX40. The plug element of any one of examples EX1 to EX39, wherein the filtration material, for example the crimped filtration material or the embossed filtration material, comprises at least one layer of a blend of cellulose and regenerated cellulose.

Example EX41. The plug element of example EX40, wherein the blend of cellulose and regenerated cellulose is free of cellulose acetate.

Example EX42. The plug element of example EX40 or EX41 , wherein the regenerated cellulose comprises regenerated cellulose fibres.

Example EX43. The plug element of example EX42, wherein the regenerated cellulose fibres are arranged substantially parallel to a longitudinal axis of the blend of cellulose and regenerated cellulose.

Example EX44. The plug element of EX42 or EX43, wherein the regenerated cellulose fibres are selected from one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres.

Example EX45. The plug element of any one of examples EX1 to EX44, wherein the plug element has a length of at least 5 millimetres. Example EX46. The plug element of example EX45, wherein the length of the plug element is at least 7 millimetres.

Example EX47. The plug element of example EX45 or EX46, wherein the length of the plug element is up to 21 millimetres.

Example EX48. The plug element of any one of examples EX45 to EX47, wherein the length of the plug element is up to 15 millimetres.

Example EX49. The plug element of any one of examples EX1 to EX48, wherein the plug element has a diameter of at least 3 millimetres.

Example EX50. The plug element of example EX49, wherein the diameter of the plug element is at least 4 millimetres.

Example EX51. The plug element of example EX49 or EX50, wherein the diameter of the plug element is up to 10 millimetres.

Example EX52. The plug element of any one of examples EX49 to EX51 , wherein the diameter of the plug element is up to 9 millimetres.

Example EX53. The plug element of any one of examples EX1 to EX50, wherein the plug element has a wall thickness of at least 0.5 millimetres.

Example EX54. The plug element of example EX53, wherein the wall thickness of the plug element is up to 3 millimetres.

Example EX55. The plug element of any one of examples EX1 to EX54, wherein an adhesive is provided between the first barrier layer and the filtration material and/or between the filtration material and the second barrier layer.

Example EX56. The plug element of example EX55, wherein the adhesive is a natural adhesive.

Example EX57. The plug element of example EX56, wherein the natural adhesive comprises starch.

Example EX58. The plug element of any one of examples EX1 to EX57, wherein the plug element is a downstream element for use in an aerosol-generating article.

Example EX59. The plug element of example EX58, wherein the plug element is one or more of a filter element, a support element, an aerosol-cooling element and a mouthpiece filter element.

Example EX60. An aerosol-generating article comprising an aerosol-generating substrate and the plug element of any one of examples EX1 to EX59, wherein the plug element is positioned downstream of the aerosol-generating substrate.

Examples will now be further described with reference to the figures in which:

FIG. 1A shows a schematic representation of a plug element according to an embodiment of the invention; FIG. 1 B shows a cross section view of the plug element of FIG. 1 A;

FIG. 10 shows an enlarged portion of the cross section view of FIG. 1 B;

FIG. 2 shows a schematic representation of the filtration material of the plug element of FIG. 1A; and

FIG. 3 shows a schematic representation of an aerosol-generating article including the plug element of FIG. 1A.

A plug element 100 will now be described with particular reference to FIG. 1A, FIG. 1 B, FIG. 10 and FIG. 2. The plug element 100 may be used in an aerosol-generating article 300, as shown in FIG. 3.

The plug element 100 is a hollow tubular element. With reference to FIG. 1A, the plug element 100 has a first end 102 and a second end 104 defining a length 106 therebetween. In examples of the invention, the length 106 of the plug element 100 may be between approximately 5 millimetres and approximately 15 millimetres.

The plug element 100 is generally cylindrical and has a diameter 108. The diameter 108 of the plug element 100 may be, for example between approximately 3 millimetres and approximately 10 millimetres.

The generally cylindrical plug element 100 has an outer surface 110.

Referring now to FIG. 1 B, it can be seen that the outer surface 110 is formed by a first barrier layer 112. The first barrier layer 112 is a sheet of a cellulose-based material, for example a processed paper material such as glassine paper, parchment paper or natural greaseproof paper.

The plug element 100 also has an inner surface 114, which is formed by a second barrier layer 116. The second barrier layer 116 is also a sheet of a cellulose-based material, which may be, for example a cardboard or extruded starch material.

The second barrier layer 116 defines a hollow core 118.

A filtration material 120 is sandwiched between the first barrier layer 112 and the second barrier layer 116. The filtration material 120 includes at least one layer of a regenerated cellulose material, for example a fibrous regenerated cellulose material. The regenerated cellulose fibres, which are described in more detail with reference to FIG. 2, may include one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres.

Advantageously, the first barrier layer 112, the second barrier layer 116 and the filtration material 120 are free of cellulose acetate.

As shown in FIG. 1C, the first barrier layer 112 has a thickness 122 and the second barrier layer 116 has a thickness 124. The thickness 122 of the first barrier layer 112 may be between approximately 50 micrometres and approximately 85 micrometres. The thickness 124 of the second barrier layer 116 may be between approximately 100 micrometres and approximately 160 micrometres.

The first barrier layer 112, the second barrier layer 116 and the filtration material 120 together define a wall of the plug element 100. The wall has a wall thickness 126. The wall thickness 126 may be between approximately 0.5 millimetres and approximately 3 millimetres.

A first layer of adhesive 128, for example a natural adhesive such as a starch-based adhesive, is provided between the first barrier layer 112 and the filtration material 120. A second layer of adhesive 130, for example a natural adhesive such as a starch-based adhesive is provided between the second barrier layer 116 and the filtration material.

The filtration material 120 will now be described with particular reference to FIG. 2. The filtration material 120 includes a plurality of regenerated cellulose fibres 202, for example one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres. In particularly advantageous embodiments of the invention, the regenerated cellulose fibres 202 may include biodegradable fibres, such as viscose fibres and/or lyocell fibres. The regenerated cellulose fibres 202 are aligned along a longitudinal axis 204 of the filtration material 120.

To form the plug element 100, a first side of the filtration material 120 is adhered to the first barrier layer 112 using the first adhesive 128. An opposing second side of the filtration material 120 is adhered to the second barrier layer 116 using the second adhesive 130. In this way the filtration material 120 is sandwiched between the first barrier layer 112 and the second barrier layer 116.

The resulting material may be rolled to form a cylinder. The cylinder is cut into lengths 106 to form plug elements 100.

In examples of the invention, the filtration material 120 may be an embossed filtration material.

An embossed filtration material may be prepared as follows.

In a first step, an appropriate type of paper including a plurality of regenerated cellulose fibres 202, for example one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres that can withstand the embossing process and meet the desired filtration specifications, is selected.

The prepared paper is fed through embossing rollers. Thes embossing rollers have engraved patterns that press into the paper, creating the desired texture. The patterns can vary depending on the specific requirements of the filter rod.

During the embossing process, pressure is applied to ensure the pattern is properly imprinted onto the paper. In some embossing processes, heat may also be applied to enable the imprinting of the pattern onto the paper. The combination of pressure and heat helps to set the embossing pattern, making it durable and effective. Paper embossing involves creating raised or recessed designs on the paper surface. This is achieved by pressing the paper between two dies, one with a raised pattern and the other with a corresponding recessed pattern. Embossing can be used to create specific textures or patterns that may influence the airflow and filtration properties. The embossing pattern may be, for example, selected according to the requirements of the filter, for example characteristics of the filter performance.

A diamond pattern, for example, results in an increased surface area as well as enhanced structural integrity, making it ideal for high-efficiency filtration.

A wave pattern beneficially enables airflow to be controlled and can enhance the absorption capacity of the filter. A wave pattern may, for example, be employed in applications where smooth airflow is desirable.

A honeycomb pattern provides a large surface area for filtration, is effective in capturing fine particles and is strong a durable.

A grid pattern provides both structural support and increased surface area.

A custom embossing pattern, for example including a logo or other texture, may also be used for branding purposes, as well as to enhance filtration properties.

Advantages of including an embossed filtration material include inter alia enhanced filtration (the increased surface area enables more particles to be trapped, certain embossing patterns may be selected to further enhance the filtration efficiency), improved RTD (providing a more controlled user experience), structural integrity (resulting in a strong, more rigid filter), customisability (allowing for a variety of patterns and textures), minimal dust creation from the processed paper material.

Referring now to FIG. 3, there is an aerosol-generating article 300. The aerosol-generating article 300 has an upstream end 302 and a downstream end 304. A front plug 306 is provided toward or at the upstream end 302. An aerosol-generating substrate 308 is provided adjacent the front plug 306. A mouthpiece filter element 310 is provided at the downstream end 304. A downstream element 312 is provided between the aerosol-generating substrate 308 and the mouthpiece filter element 310. The downstream element 312 may be, for example, a support element or an aerosol-cooling element.

A plug element 100 according to the invention may be provided in the aerosol-generating article 300. The plug element 100 may be provided, for example, downstream of the aerosolgenerating substrate 308. The plug element 100 may provide the function of one or more of a filter element, a support element, an aerosol-cooling element and a mouthpiece filter element. In other words, the plug element 100 may be positioned in place of the downstream element 312 and/or the mouthpiece filter element 310 of the aerosol-generating article 300 as shown in FIG. 3. Advantageously, the plug element 100 may be used to replace hollow acetate tubes (HATs), flat hollow acetate tubes (FHATs) in aerosol-generating articles 300. Since the plug element 100 described is free of cellulose acetate, the single-use plastic content of the aerosol-generating article 300 is reduced.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 1% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1. A plug element for use in an aerosol-generating article, the plug element comprising: a first barrier layer; a second barrier layer; and an embossed filtration material; wherein the embossed filtration material is sandwiched between the first barrier layer and the second barrier layer and comprises regenerated cellulose.

2. The plug element of claim 1 , wherein the first barrier layer forms an outer surface of the plug element.

3. The plug element of claim 1 or 2, wherein the first barrier layer comprises a sheet, a film or a coating, for example wherein the sheet, the film or the coating comprises a cellulose-based material.

4. The plug element of claim 3, wherein the cellulose-based material is a processed paper material selected from the group consisting of glassine paper, parchment paper and natural greaseproof paper.

5. The plug element of any one of claims 1 to 4, wherein the first barrier layer has a grammage of between approximately 20 grams per squared metre and approximately 30 grams per squared metre.

6. The plug element of any one of claims 1 to 5, wherein the second barrier layer forms an inner surface of the plug element.

7. The plug element of any one of claims 1 to 6, wherein the second barrier layer comprises a sheet, a film or a coating, for example wherein the sheet, the film or the coating comprises a cellulose-based material.

8. The plug element of claim 7, wherein the cellulose-based material is a processed paper, cardboard or extruded starch material.

9. The plug element of any one of claims 1 to 8, wherein the second barrier layer has a grammage of between approximately 80 grams per squared metre and approximately 115 grams per squared metre.

10. The plug element of any one of claims 1 to 9, wherein the embossed filtration material comprises at least one layer of regenerated cellulose material.

11. The plug element of claim 10, wherein the regenerated cellulose material comprises regenerated cellulose fibres, for example wherein the regenerated cellulose fibres are selected from one or more of viscose fibres, rayon fibres, modal fibres, tencel fibres and lyocell fibres.

12. The plug element of any one of claims 1 to 11 , wherein an adhesive is provided between the first barrier layer and the filtration material and/or between the filtration material and the second barrier layer, for example wherein the adhesive is a natural adhesive.

13. The plug element of any one of claims 1 to 12, wherein the plug element is a downstream element for use in an aerosol-generating article, for example wherein the plug element is one or more of a filter element, a support element, an aerosol-cooling element and a mouthpiece filter element.

14. An aerosol-generating article comprising an aerosol-generating substrate and the plug element of any one of claims 1 to 13, wherein the plug element is positioned downstream of the aerosol-generating substrate.