AEROSOL-GENERATING ARTICLE COMPRISING A DOWNSTREAM ELEMENT COMPRISING A PAPER MATERIAL

Description

The present invention relates to an aerosol-generating article comprising at least one element formed from a biodegradable filtration material. In particular, the present invention relates to an aerosol-generating article comprising a downstream element located downstream of, and in axial alignment with, an aerosol-generating substrate, the downstream element comprising a plug element formed from a biodegradable cellulosic filtration material.

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.

A number of aerosol-generating articles in which tobacco is heated rather than combusted have also been proposed in the art. In heated aerosol-generating articles, an aerosol is generated by heating an aerosol-generating substrate, such as tobacco. Known heated aerosol-generating articles include, for example, smoking articles in which an aerosol is generated by electrical heating or by the transfer of heat from a combustible fuel element or heat source to an aerosol-generating substrate. During smoking, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and entrained in air drawn through the smoking article. As the released compounds cool they condense to form an aerosol that is inhaled by the consumer. Many known heated aerosol-generating articles comprise one or more elements formed of a fibrous filtration material.

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 (SUPs). The term SUPs 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. 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).

Further, it would be desirable to provide such an aerosol-generating article that gives an acceptable sensory experience to the consumer. In particular, it would be desirable for the component to be formed of a biodegradable filtration material that has very little or no impact on the taste perceived by the consumer during use of the aerosol-generating article, and that generally does not adversely impact the smoking experience.

In addition, it would be desirable to provide such an aerosol-generating article that can be readily manufactured using existing high speed techniques and apparatus requiring only minimal modifications.

Furthermore, it would be desirable for the filtration material to be such that it can be effectively formed into components that provide an acceptable appearance and feeling to the consumer. For example, it would be desirable for the filtration material to be such that it can be effectively formed into components for an aerosol-generating article, which provide a desirable density, firmness and resistance to draw (RTD).

The present disclosure relates to an aerosol-generating article. The aerosol-generating article may comprise an aerosol-generating substrate. Further, the aerosol-generating article may comprise a downstream element. The downstream element may be provided downstream of the aerosol-generating substrate. The downstream element may be provided in axial alignment with the aerosol-generating substrate.

The downstream element may comprise a plug element. The plug element may comprise a cellulosic filtration material. The cellulosic filtration material may comprise a paper material. The cellulosic filtration material may comprise an additive coating applied to the paper material.

The additive coating may comprise at least 5 percent by weight of exogenous lignin on a dry weight basis. An overall content of lignin in the plug element may be at least 2 percent by weight of the plug element.

According to a first aspect of the present invention, there is provided an aerosol-generating article comprising an aerosol-generating substrate; and a downstream element provided downstream of the aerosol-generating substrate and in axial alignment with the aerosol-generating substrate. The downstream element comprises a plug element. The plug element comprises a cellulosic filtration material comprising a paper material and an additive coating applied to the paper material. The additive coating comprises at least 10 percent by weight of exogenous lignin on a dry weight basis. An overall content of lignin in the plug element is at least 2 percent by weight of the plug element.

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 aerosol-generating 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 “transverse” is used to describe the direction perpendicular to the longitudinal direction. Unless otherwise stated, references to the “cross-section” of the aerosol-generating article or a component of the aerosol-generating article refer to the transverse cross-section.

As used herein with reference to the invention, the term “width” denotes the maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in a transverse direction. Where the aerosol-generating article has a substantially circular cross-section, the width of the aerosol-generating article corresponds to the diameter of the aerosol-generating article. Where a component of the aerosol-generating article has a substantially circular cross-section, the width of the component of the aerosol-generating article corresponds to the diameter of the component of the aerosol-generating article.

As used herein with reference to the invention, the term “rod” is used to denote a generally cylindrical element having a substantially circular, oval or elliptical cross-section.

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.

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

The expression “resistance to draw (RTD) per unit length” of a particular component (or element) of the aerosol-generating article, such as the upstream element, the aerosol-generating element, and so forth, can be calculated by dividing the measured resistance to draw of the component by the total axial length of the component. The RTD per unit length refers to the pressure required to force air through a unit length of a component. Throughout the present disclosure, a unit length refers to a length of 1 millimetre. Accordingly, in order to derive the RTD per unit length of a particular component, a specimen of a particular length, 15 millimetres for example, of the component can be used in measurement. The RTD of such a specimen is measured in accordance with ISO 6565-2015. If, for example, the measured RTD is about 15 millimetres H₂O, then the RTD per unit length of the component is about 1 millimetre H₂O per millimetre. The RTD per unit length of the component is generally dependent on the structural properties of the material used for the component as well as the cross-sectional geometry or profile of the component, amongst other factors.

The aerosol stream generated during use of an aerosol-generating article is a complex mixture of chemicals, including semi-solid particles dispersed in a fluid matrix of vapours and permanent gases. As used herein with reference to the invention, the term “filtration efficiency” is used to describe the ability of an element comprising a filtration material to capture particulate matter contained in such aerosol stream. In practice, the term “filtration efficiency” denotes the fraction of the overall dry particulate matter carried in the aerosol stream that is retained within the element comprising filtration material during use.

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, the term “flue gases” is used to denote gaseous products generated by the combustion or pyrolysis of an aerosol-generating substrate.

The present invention provides an improved aerosol-generating article comprising at least one downstream element, the downstream element comprising a plug element formed of a cellulosic filtration material comprising a combination of a paper material and an additive coating comprising exogenous lignin. 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 a paper material in place of cellulose acetate fibres to form elements such as filtration elements, thereby significantly improving the biodegradability of the aerosol-generating article.

The addition of the additive coating to the paper material has advantageously been found to significantly improve the filtration properties of the downstream element. In particular, the use of an additive coating including exogenous lignin has been found to significantly improve the reduction of phenols and other undesirable compounds from the mainstream smoke or aerosol, compared to the use of a paper material alone. The composition of the additive coating can advantageously be modified to optimise the filtration efficiency of the downstream element, such that it can achieve a similar reduction in phenols and other undesirable compounds as a conventional cellulose acetate tow. For example, as polarity may play an important role in the ability of a material to filter certain compounds, a hydrophobic additive coating may be used to at least partly counter the hydrophilic nature of the paper material.

As defined above, the plug element of the downstream element of aerosol-generating articles according to the present invention comprises a paper material to which an additive coating has been applied.

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. In some embodiments, the sheet may have a thickness ranging from 0.03 to 2 millimetres and a basis weight of from 50 grams per square metre to 300 grams per square metre.

The paper material is obtained from cellulosic pulp. This includes both mechanical pulp and chemical pulp. Mechanical pulp is produced by using only mechanical attrition to pulp lignocellulosic materials, with the aid of water or steam but without using chemicals. Chemical pulp is obtained by treating lignocellulosic materials with chemicals such as sulphates, sulphites, bleach, etc. To form the paper material, the cellulosic pulp may be subjected to different processes, and the web of cellulosic fibres may be woven, non-woven, air-laid, wet-laid or the paper material may be obtained by foam-forming or friction-spinning.

The paper material may be hammermilled. Without wishing to be bound by theory, this is understood to reduce the crystallinity of cellulose, so that a more amorphous sheet is obtained. More amorphous sheets have been observed to capture flue gases more efficiently.

Types of paper material suitable for manufacturing a plug element for use in aerosol-generating articles in accordance with the present invention include paper, paperboard, paper tissue, paper towel. The term “paper” is typically used to denote a web of cellulosic fibres in sheet form, wherein the sheet has a thickness ranging from 0.03 to 0.20 millimetres. The term “paperboard” is typically used to denote a web of cellulosic fibres in sheet form, wherein the sheet has a thickness ranging from 0.20 to 2.00 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.

Advantageously, using a paper material, which comprises randomly oriented cellulose fibres, 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.

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 (C₆H₁₀O₅)_n. 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.

In the context of the present invention, the term “endogenous lignin” is used to denote the residual lignin content that is found in the paper material at the end of the papermaking process.

For example, kraft paper material—that is, paper or paperboard produced from pulp obtained by treating wood chips with a hot aqueous solution of sodium hydroxide and sodium sulphide—has a low endogenous lignin content (below 10 percent by weight, and in some instances as low as 2-6 percent by weight). This is because the aggressive chemical pulping process by which it is obtained breaks down the lignin molecules into smaller soluble fragments, whilst isolating the cellulose fibres, and so the great majority of the lignin is removed. Less fine paper materials may have comparatively high endogenous lignin contents. Newspaper, for example, may often content from 18÷30 percent by weight of lignin.

As used herein with reference to the invention, the term “exogenous lignin” is used to denote lignin incorporated into the additive coating that may be applied to a plug element comprising a paper material having a certain endogenous lignin content. The exogenous lignin is provided in an isolated form and has been extracted and separated from other components of the plant material from which it derives. The exogenous lignin is therefore provided extrinsically from any cellulosic plant material that is present. In other words, the term “exogenous lignin” refers to a separate and distinct source of lignin to any lignin provided intrinsically within the paper material. The same definition of “exogenous” applies in relation to hemicellulose.

Following application of exogenous lignin to the paper material of the plug element, an “overall lignin content” in the plug element is understood to be the sum of a) the endogenous lignin content present in the plug element prior to application of exogenous lignin, and b) the amount of exogenous lignin applied to the paper material.

As part of the papermaking process, fillers may be added to the pulp fibres prior to the formation of the web. Fillers used in the papermaking process are ordinarily inorganic, particulate substances, typically in the size range of 0.1 to 10 micrometres that may impart certain desirable properties to the paper material. For example, fillers may have an impact on the structure, appearance (for example, brightness and opacity), density, tensile strength and other measurable properties of the paper material. Examples of commonly used papermaking fillers include clay, limestone, chalk, talc, calcite, rutile (titanium dioxide), calcium sulphate, amorphous silica.

Paper material for use in the manufacture of a plug element of an aerosol-generating article in accordance with the present invention may include one or more of the papermaking fillers described above.

Preferably, the paper material does not include cellulose acetate fibres or any other fibres formed of non-biodegradable polymers.

In the plug element, the 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 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.

The plug element may comprise a single sheet of paper material that is gathered or otherwise processed to be formed into rod shape. Alternatively, the plug element may comprise two or more sheets that are gathered or otherwise processed together to be formed into rod shape. For example, two or more sheets of paper material may be laid on top of each other and gathered or otherwise processed at once to form the plug element. Two or more sheets of paper material may also be gathered or otherwise processed independently, in parallel to each other, and then combined to form the plug element.

The plug element may comprise a plurality of sheets of paper material stacked on top of each other. The resulting stack may have a thickness of up to 10 millimetres. The stack may be slitted into rod-shaped elements to form plug elements for use in an aerosol-generating article according to the present invention.

Prior to being formed into a rod or hollow tubular element, the web or sheet of 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 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 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 paper material to form a rod. However, it will be appreciated that crimped sheets of 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 by facilitating contact between the aerosol or smoke flowing through the plug element and the additive coating.

In certain embodiments, sheets of 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 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 whole width of the sheet.

Gathering or winding the sheet of 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.

As described briefly above, the sheet of paper material may have a basis weight of at least 10 grams per square metre. Preferably, the sheet of paper material may have a basis weight of at least 15 grams per square metre. More preferably, the sheet of paper material may have a basis weight of at least 20 grams per square metre. Even more preferably, the sheet of paper material may have a basis weight of at least 30 grams per square metre.

The sheet of paper material may have a basis weight of less than or equal to 200 grams per square metre. Preferably, the sheet of paper material may have a basis weight of less than or equal to 180 grams per square metre. More preferably, the sheet of paper material may have a basis weight of less than or equal to 160 grams per square metre. Even more preferably, the sheet of paper material may have a basis weight of less than or equal to 120 grams per square metre. In particularly preferred embodiments, the sheet of paper material may have a basis weight of less than or equal to 100 grams per square metre.

The basis weight of the sheet of paper material 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 paper material to be able to form it into a desired shape. Further, the basis weight of the sheet of 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.

As described briefly above, the sheet of paper material may have a thickness of up to 800 micrometres. Preferably, the sheet of paper material has a thickness of less than or equal to 600 micrometres. More preferably, the sheet of paper material has a thickness of less than or equal to 600 micrometres. Even more preferably, the sheet of paper material has a thickness of less than or equal to 500 micrometres.

In preferred embodiments, the sheet of paper material has a thickness of less than or equal to 300 micrometres, preferably less than or equal to 200 micrometres, more preferably less than or equal to 100 micrometres.

The sheet of paper material may have a thickness of at least 10 micrometres. Preferably, the sheet of paper material has a thickness of at least 15 micrometres. More preferably, the sheet of paper material has a thickness of at least 20 micrometres. Even more preferably, the sheet of paper material has a thickness of at least 30 micrometres.

In preferred embodiments, the sheet of paper material has a thickness of at least 40 micrometres, preferably at least 50 micrometres, more preferably at least 60 micrometres.

The thickness of the sheet may be selected to ensure a certain pliability of the sheet, so as to enable one or more of crimping, gathering, pleating, and folding of the sheet.

The plug element may have a weight of less than or equal to about 100 milligrams, less than or equal to about 75 milligrams, or less than or equal to about 50 milligrams.

The plug element may have a weight of at least about 10 milligrams, at least about 15 milligrams, or at least about 20 milligrams.

The plug element may have a weight of between about 10 milligrams and about 100 milligrams, between about 10 milligrams and about 75 milligrams, or between about 10 milligrams and about 50 milligrams.

The plug element may have a weight of between about 15 milligrams and about 100 milligrams, between about 15 milligrams and about 75 milligrams, or between about 15 milligrams and about 50 milligrams.

The plug element may have a weight of between about 20 milligrams and about 100 milligrams, between about 20 milligrams and about 75 milligrams, or between about 20 milligrams and about 50 milligrams.

The plug element may have an average weight per unit length of less than or equal to about 20 milligrams per millimetre, less than or equal to about 15 milligrams per millimetre, or less than or equal to about 10 milligrams per millimetre.

As used herein with reference to the invention, the average weight per unit length of the plug element is equal to the weight of the plug element divided by the length of the plug element. For example, where the plug element has a weight of 25 milligrams and a length of 5 millimetres, the average weight per unit length of the plug element is 5 milligrams per millimetre.

The plug element may have an average weight per unit length of at least about 2 milligrams per millimetre, at least about 3 milligrams per millimetre, or at least about 4 milligrams per millimetre.

The plug element may have an average weight per unit length of between about 2 milligrams per millimetre and about 20 milligrams per millimetre, between about 2 milligrams per millimetre and about 15 milligrams per millimetre, or between about 2 milligrams per millimetre and about 10 milligrams per millimetre.

The plug element may have an average weight per unit length of between about 3 milligrams per millimetre and about 20 milligrams per millimetre, between about 3 milligrams per millimetre and about 15 milligrams per millimetre, or between about 3 milligrams per millimetre and about 10 milligrams per millimetre.

The plug element may have an average weight per unit length of between about 4 milligrams per millimetre and about 20 milligrams per millimetre, between about 4 milligrams per millimetre and about 15 milligrams per millimetre, or between about 4 milligrams per millimetre and about 10 milligrams per millimetre.

In plug elements for use in aerosol-generating articles in accordance with the present invention, the additive coating may cover at least part of the external surface of at least one side of the sheet of paper material. Preferably, the additive coating covers at least part of the external surface of both sides of the sheet of paper material.

The additive coating may be applied over a part of the external surface of at least one side of the sheet of paper material. Preferably, the additive coating is applied over a part of the external surface of both sides of the sheet of paper material.

Alternatively, the additive coating may be applied over substantially all of the external surface of at least one side of the sheet of paper material. Preferably, the additive coating may be applied over substantially all of the external surface of at least one side of the sheet of paper material.

Thus, in aerosol-generating articles in accordance with the present invention, the additive coating may be applied to the paper material to form a defined layer on at least part of the external surface of at least one side of the paper material. In some embodiments, the additive coating may be applied to the paper material to form a defined layer on at least part of the external surface of both sides of the paper material. For example, this may be achieved by applying the additive coating to the paper material by a conventional printing process (for example, gravure printing or flexographic printing) or by a known coating process (for example, curtain coating, reverse gravure, semi-flexo, rod-coating, blade coating, comma coating, slot die coating).

The application of the additive coating to the external surface of the paper material advantageously maximises the contact between the mainstream smoke or aerosol passing through the downstream element during use and the additive coating. This in turn maximises the capability of the additive coating to reduce phenols and other undesirable compounds in the smoke or aerosol.

However, depending on the porosity of the paper material and due to the natural tendency of the paper material to absorb liquids such as water, applying the additive coating to the paper material may typically result in at least some of the additive coating permeating into the paper material, so that at least some of the volume of the paper material is soaked with additive coating. This may occur, in particular, if the additive coating is provided in the form of an aqueous solution or dispersion.

Therefore, in aerosol-generating articles in accordance with the present invention, the additive coating may alternatively, or additionally, be applied to the paper material not to form a defined layer on at least part of the external surface of at least one side of the paper material, but rather to at least partly impregnate the volume of the paper material. In such case, the coating additive does not form a defined layer on the external surface of the paper material. Instead, the coating additive is absorbed into the paper material and, upon drying, forms a deposit onto the fibrous fraction of the paper material (that is, on the individual cellulose fibres contained in the paper material). For example, at least partial impregnation of the paper material with the additive coating may be achieved by technologies such as “dip and squeeze”, spray application, comma application, or by using conventional or film type size presses or blade applicators.

The provision of such deposit of additive coating on the cellulose fibres of the paper material, combined with the inherent porosity of the paper material, advantageously ensures that the mainstream smoke or aerosol passing through the downstream element contacts the additive coating during use, and this interaction promotes the reduction of phenols and other undesirable compounds in the smoke or aerosol.

The plug element may comprise at least 1 percent by weight of the additive coating. Preferably, the plug element comprises at least 2 percent by weight of the additive coating, more preferably at least 3 percent by weight of the additive coating, more preferably at least 4 percent by weight of the additive coating, more preferably at least 5 percent by weight of the additive coating, on a dry weight basis.

The plug element may comprise up to 15 percent by weight of the additive coating, preferably up to 12 percent by weight of the additive coating, more preferably up to 10 percent by weight of the additive coating, on a dry weight basis.

The additive coating comprises at least one additive for reducing phenols. That is, the additive coating comprises at least one additive which is capable of capturing or otherwise converting at least some of the phenols and phenol derivatives produced upon heating or burning of the aerosol-generating substrate. Preferably, the additive coating comprises at least one additive for reducing other undesirable compounds from the mainstream aerosol, such as carbon monoxide.

Preferably, the additive coating is biodegradable such that the cellulosic filtration material including the combination of additive coating and paper material is biodegradable.

According to the invention, the additive coating comprises at least 5 percent by weight of exogenous lignin, on a dry weight basis. Preferably, the additive coating comprises at least 6 percent by weight of exogenous lignin, more preferably at least 8 percent by weight of exogenous lignin, more preferably at least 10 percent by weight of exogenous lignin, more preferably at least 12 percent by weight of exogenous lignin, more preferably at least 15 percent by weight of exogenous lignin, on a dry weight basis.

The additive coating preferably comprises up to 50 percent by weight of exogenous lignin, more preferably up to 45 percent by weight of exogenous lignin, more preferably up to 40 percent by weight of exogenous lignin, more preferably up to 35 percent by weight of exogenous lignin, even more preferably up to 30 percent by weight, on a dry weight basis.

For example, the additive coating may comprise between 5 percent by weight and 50 percent by weight of exogenous lignin, or between 6 percent by weight and 50 percent by weight of exogenous lignin, or between 8 percent by weight and 50 percent by weight of exogenous lignin, or between 10 percent by weight and 50 percent by weight of exogenous lignin, or between 12 percent by weight and 50 percent by weight of exogenous lignin, or between 15 percent by weight and 50 percent by weight of exogenous lignin, or between 5 percent by weight and 45 percent by weight of exogenous lignin, or between 6 percent by weight and 45 percent by weight of exogenous lignin, or between 8 percent by weight and 45 percent by weight of exogenous lignin, or between 10 percent by weight and 45 percent by weight of exogenous lignin, or between 12 percent by weight and 45 percent by weight of exogenous lignin, or between 15 percent by weight and 45 percent by weight of exogenous lignin, or between 5 percent by weight and 40 percent by weight of exogenous lignin, or between 6 percent by weight and 40 percent by weight of exogenous lignin, or between 8 percent by weight and 40 percent by weight of exogenous lignin, or between 10 percent by weight and 40 percent by weight of exogenous lignin, or between 12 percent by weight and 40 percent by weight of exogenous lignin, or between 15 percent by weight and 40 percent by weight of exogenous lignin, or between 5 percent by weight and 35 percent by weight of exogenous lignin, or between 6 percent by weight and 35 percent by weight of exogenous lignin, or between 8 percent by weight and 35 percent by weight of exogenous lignin, or between 10 percent by weight and 35 percent by weight of exogenous lignin, or between 12 percent by weight and 35 percent by weight of exogenous lignin, or between 15 percent by weight and 35 percent by weight of exogenous lignin, or between 5 percent by weight and 30 percent by weight of exogenous lignin, or between 6 percent by weight and 30 percent by weight of exogenous lignin, or between 8 percent by weight and 30 percent by weight of exogenous lignin, or between 10 percent by weight and 30 percent by weight of exogenous lignin, or between 12 percent by weight and 30 percent by weight of exogenous lignin, or between 15 percent by weight and 30 percent by weight of exogenous lignin, on a dry weight basis.

Lignin provides numerous active functional groups that are capable of scavenging phenols, including acetyl groups. The inclusion of lignin in the paper material therefore reduces the phenols in the mainstream aerosol as it passes through the downstream plug element from the aerosol-generating substrate.

For the purposes of the present invention, the exogenous lignin may be extracted from any plant source. For example, the exogenous lignin may be extracted from weed straw pulp or wood pulp.

In certain preferred embodiments of the present invention, the exogenous lignin may be in the form of acetylated lignin. Acetylated lignin is a form of modified lignin, which has been modified to increase the number of acetyl groups. As a result of the increased number of acetyl groups, the use of acetylated lignin may further improve the capabilities of lignin in reducing phenols from the mainstream aerosol.

Without wishing to be bound by theory, the introduction of acetyl groups is understood to also have an impact on wettability of the paper material. In fact, the esterification reaction that occurs between the acetyl groups and at least some hydroxyl groups in the cellulose molecules induces a change in the nature of at least some of the cellulose fibres from hydrophilic to hydrophobic. Thus, the paper material to which an additive coating comprising acetylated lignin has been applied may have a reduced tendency to absorb moisture from the smoke or aerosol flowing through the plug element. This is desirable in that it may counter the effect, which has been observed with some conventional cellulose acetate filters and is often referred to as ‘dry smoke’, whereby the smoke or aerosol delivered to the consumer has a significantly reduced moisture content and may, therefore, under certain conditions, be perceived as undesirably dry. Further, increasing the contact angle of the paper material contact angle, such as for example increasing the contact angle of the paper material to greater than 90 degrees, preferably to greater than 105 degrees, may advantageously reduce the ability of the paper material to scavenge nicotine from the smoke or aerosol.

In certain preferred embodiments of the present invention, the exogenous lignin may be in the form of organosolv lignin. Organosolv lignin is lignin that has been produced using an organosolv pulping technique which employs aqueous organic solvents to solubilise the lignin. The use of organosolv lignin is desirable due to its high purity and low ash content.

In certain preferred embodiments of the present invention, the exogenous lignin may be light-coloured, nearly white or white lignin. Such lignin is lighter than standard lignin, which is typically yellow or brown in colour. The use of a light-coloured, nearly white or white lignin may be advantageous since the exogenous lignin will have a colour that is closer to that of the fibrous material to which the additive coating is applied. The exogenous lignin will therefore not be visible within the cellulosic filtration material, such that the overall appearance of the cellulosic filtration material can be similar to a conventional filter of a smoking article.

Suitable processes for producing light-coloured, nearly white or white lignin would be known to the skilled person. Examples of suitable processes are described in EP 3707194 A1.

As described briefly above, in aerosol-generating articles according to the invention an overall content of lignin in the plug element on a dry weight basis is at least 2 percent by weight, preferably at least 3 percent by weight, more preferably at least 4 percent by weight, even more preferably at least 5 percent by weight.

An overall content of lignin in the plug element on a dry weight basis may be up to 20 percent by weight. Preferably an overall content of lignin in the plug element on a dry weight basis is up to 18 percent by weight, more preferably up to 15 percent by weight, even more preferably up to 12 percent by weight. In some embodiments, an overall content of lignin in the plug element on a dry weight basis is up to 10 percent by weight.

For example, an overall content of lignin in the plug element on a dry weight basis is from 2 percent by weight to 20 percent by weight, preferably from 3 percent by weight to 20 percent by weight, more preferably from 4 percent by weight to 20 percent by weight, even more preferably from 5 percent by weight to 20 percent by weight.

For example, an overall content of lignin in the plug element on a dry weight basis is from 2 percent by weight to 18 percent by weight, preferably from 3 percent by weight to 18 percent by weight, more preferably from 4 percent by weight to 18 percent by weight, even more preferably from 5 percent by weight to 18 percent by weight.

For example, an overall content of lignin in the plug element on a dry weight basis is from 2 percent by weight to 15 percent by weight, preferably from 3 percent by weight to 15 percent by weight, more preferably from 4 percent by weight to 15 percent by weight, even more preferably from 5 percent by weight to 15 percent by weight.

For example, an overall content of lignin in the plug element on a dry weight basis is from 2 percent by weight to 12 percent by weight, preferably from 3 percent by weight to 12 percent by weight, more preferably from 4 percent by weight to 12 percent by weight, even more preferably from 5 percent by weight to 12 percent by weight.

For example, an overall content of lignin in the plug element on a dry weight basis is from 2 percent by weight to 10 percent by weight, preferably from 3 percent by weight to 10 percent by weight, more preferably from 4 percent by weight to 10 percent by weight, even more preferably from 5 percent by weight to 10 percent by weight.

Alternatively or in addition to the exogenous hemicellulose, the additive coating may comprise at least one exogenous polysaccharide.

The at least one exogenous polysaccharide advantageously provides additional active functional groups, such as acetyl groups, that are particularly effective at scavenging phenols and other undesirable gaseous compounds generated from the aerosol-generating substrate. The inclusion of the exogenous polysaccharide in the additive coating, in addition to the lignin, therefore further reduces the level of phenols and other undesirable gaseous compounds in the mainstream aerosol as it passes through the downstream element from the aerosol-generating substrate.

The at least one exogenous polysaccharide can bind effectively to the lignin in the additive coating and may provide the additive coating with improved temperature stability. Further, it is believed that the presence of lignin reduces the crystallinity and glass transition temperature of the polysaccharide such that the polysaccharide has an increased capacity to scavenge and store gases from the mainstream aerosol and an increased speed of absorbing the gases. The at least one exogenous polysaccharide may include one or more plant based polysaccharides. Preferably, the at least one exogenous polysaccharide comprises a plant based starch. For example, the additive coating comprises exogenous hemicellulose, corn starch, potato starch or a combination thereof. In particularly preferred embodiments, the additive coating comprises hemicellulose. In other preferred embodiments, the at least one exogenous polysaccharide comprises corn starch.

In other preferred embodiments, the at least one exogenous polysaccharide comprises a modified starch, such as acetylated starch, or oxidised starch. In other preferred embodiments, the at least one polysaccharide comprises a sugar or acetylated sugar.

Similar to what is described above in connection with acetylated lignin, the addition of acetyl groups to the starch molecule or to a sugar molecule is understood to further have some impact on wettability of the paper material. Without wishing to be bound by theory, by reacting with some of the hydroxyl groups in the cellulose molecules, the acetyl groups may contribute to shift the nature of the cellulosic fibres in the paper material from hydrophilic to hydrophobic, such as to increase the contact angle of the paper material towards values in excess 90 degrees. This may advantageously reduce the tendency of the plug element to absorb moisture and capture nicotine from the smoke or aerosol flowing through.

Preferably, the additive coating comprises at least 20 percent by weight of the at least one exogenous polysaccharide, more preferably at least 30 percent by weight of the at least one exogenous polysaccharide, more preferably at least 40 percent by weight of the at least one exogenous polysaccharide, more preferably at least 50 percent by weight of the at least one exogenous polysaccharide, on a dry weight basis.

Preferably, the additive coating comprises up to 90 percent by weight of the at least one exogenous polysaccharide, more preferably up to 85 percent by weight of the at least one exogenous polysaccharide, more preferably up to 80 percent by weight of the at least one exogenous polysaccharide, on a dry weight basis.

For example, the additive coating may comprise between 20 percent by weight and 90 percent by weight of the at least one exogenous polysaccharide, or between 30 percent by weight and 90 percent by weight of the at least one exogenous polysaccharide, or between 40 percent by weight and 90 percent by weight of the at least one exogenous polysaccharide, or between 50 percent by weight and 90 percent by weight of the at least one exogenous polysaccharide, or between 20 percent by weight and 85 percent by weight of the at least one exogenous polysaccharide, or between 30 percent by weight and 85 percent by weight of the at least one exogenous polysaccharide, or between 40 percent by weight and 85 percent by weight of the at least one exogenous polysaccharide, or between 50 percent by weight and 85 percent by weight of the at least one exogenous polysaccharide, or between 20 percent by weight and 80 percent by weight of the at least one exogenous polysaccharide, or between 30 percent by weight and 80 percent by weight of the at least one exogenous polysaccharide, or between 40 percent by weight and 80 percent by weight of the at least one exogenous polysaccharide, or between 50 percent by weight and 80 percent by weight of the at least one exogenous polysaccharide, on a dry weight basis.

Preferably, the cellulosic filtration material comprises at least 1 percent by weight of the at least one exogenous polysaccharide, more preferably at least 2 percent by weight of the at least one exogenous polysaccharide, more preferably at least 5 percent by weight of the at least one exogenous polysaccharide, even more preferably at least 6 percent by weight of the at least one polysaccharide, on a dry weight basis.

Preferably, the cellulosic filtration material comprises up to 15 percent by weight of the at least one exogenous polysaccharide, more preferably up to 12 percent by weight of the at least one exogenous polysaccharide, more preferably up to 10 percent by weight of the at least one exogenous polysaccharide, more preferably up to 8 percent by weight of the at least one exogenous polysaccharide, on a dry weight basis.

For example, the cellulosic filtration material may comprise between 1 and 15 percent by weight of the at least one exogenous polysaccharide, or between 1 percent by weight and 12 percent by weight of the at least one exogenous polysaccharide, or between 1 percent by weight and 10 percent by weight of the at least one exogenous polysaccharide, or between 1 percent by weight and 8 percent by weight of the at least one exogenous polysaccharide, or between 2 and 15 percent by weight of the at least one exogenous polysaccharide, or between 2 percent by weight and 12 percent by weight of the at least one exogenous polysaccharide, or between 2 percent by weight and 10 percent by weight of the at least one exogenous polysaccharide, or between 2 percent by weight and 8 percent by weight of the at least one exogenous polysaccharide, or between 5 and 15 percent by weight of the at least one exogenous polysaccharide, or between 5 percent by weight and 12 percent by weight of the at least one exogenous polysaccharide, or between 5 percent by weight and 10 percent by weight of the at least one exogenous polysaccharide, or between 5 percent by weight and 8 percent by weight of the at least one exogenous polysaccharide, or between 6 and 15 percent by weight of the at least one exogenous polysaccharide, or between 6 percent by weight and 12 percent by weight of the at least one exogenous polysaccharide, or between 6 percent by weight and 10 percent by weight of the at least one exogenous polysaccharide, or between 6 percent by weight and 8 percent by weight of the at least one exogenous polysaccharide, on a dry weight basis.

The weight ratio of the at least one exogenous polysaccharide to the exogenous lignin in the additive coating is preferably at least 2, more preferably at least 2.5, more preferably at least 3, more preferably at least 3.5, more preferably at least 4. The weight ratio of the at least one polysaccharide to the exogenous lignin in the additive coating may be up to 6.

The additive coating preferably comprises an exogenous hemicellulose. Preferably, the additive coating comprises at least 5 percent by weight of exogenous hemicellulose, more preferably at least 6 percent by weight of exogenous hemicellulose, more preferably at least 8 percent by weight of exogenous hemicellulose, more preferably at least 10 percent by weight of exogenous hemicellulose, on a dry weight basis.

Preferably, the additive coating comprises up to 50 percent by weight of exogenous hemicellulose, more preferably up to 45 percent by weight of exogenous hemicellulose, more preferably up to 40 percent by weight of exogenous hemicellulose, more preferably up to 35 percent by weight of exogenous hemicellulose, even more preferably up to 30 percent by weight of exogenous hemicellulose, on a dry weight basis.

For example, the additive coating may comprise between 5 percent by weight and 50 percent by weight of exogenous hemicellulose, or between 6 percent by weight and 50 percent by weight of exogenous hemicellulose, or between 8 percent by weight and 50 percent by weight of exogenous hemicellulose, or between 10 percent by weight and 50 percent by weight of exogenous hemicellulose, or between 5 percent by weight and 45 percent by weight of exogenous hemicellulose, or between 6 percent by weight and 45 percent by weight of exogenous hemicellulose, or between 8 percent by weight and 45 percent by weight of exogenous hemicellulose, or between 10 percent by weight and 45 percent by weight of exogenous hemicellulose, or between 5 percent by weight and 40 percent by weight of exogenous hemicellulose, or between 6 percent by weight and 40 percent by weight of exogenous hemicellulose, or between 8 percent by weight and 40 percent by weight of exogenous hemicellulose, or between 10 percent by weight and 40 percent by weight of exogenous hemicellulose, or between 5 percent by weight and 35 percent by weight of exogenous hemicellulose, or between 6 percent by weight and 35 percent by weight of exogenous hemicellulose, or between 8 percent by weight and 35 percent by weight of exogenous hemicellulose, or between 10 percent by weight and 35 percent by weight of exogenous hemicellulose, or between 5 percent by weight and 30 percent by weight of exogenous hemicellulose, or between 6 percent by weight and 30 percent by weight of exogenous hemicellulose, or between 8 percent by weight and 30 percent by weight of exogenous hemicellulose, or between 10 percent by weight and 30 percent by weight of exogenous hemicellulose, on a dry weight basis.

Hemicellulose provides numerous active functional groups that are capable of scavenging phenols and other undesirable gaseous compounds generated from the aerosol-generating substrate. The inclusion of hemicellulose in the cellulosic filtration material, in addition to lignin, therefore further reduces the level of phenols and certain other undesirable gaseous compounds in the mainstream aerosol as it passes through the downstream plug element from the aerosol-generating substrate.

For the purposes of the present invention, the exogenous hemicellulose may be extracted from any plant source. For example, the exogenous hemicellulose may be extracted from weed straw pulp or wood pulp. The lignin and hemicellulose may be extracted from the same plant source.

In aerosol-generating articles according to the invention an overall content of hemicellulose in the plug element on a dry weight basis is at least 15 percent by weight, preferably at least 16 percent by weight, more preferably at least 18 percent by weight, even more preferably at least 20 percent by weight.

An overall content of hemicellulose in the plug element on a dry weight basis may be up to 30 percent by weight. Preferably an overall content of hemicellulose in the plug element on a dry weight basis is up to 28 percent by weight, more preferably up to 26 percent by weight, even more preferably up to 24 percent by weight. In some embodiments, an overall content of hemicellulose in the plug element on a dry weight basis is up to 22 percent by weight.

For example, an overall content of hemicellulose in the plug element on a dry weight basis is from 15 percent by weight to 30 percent by weight, preferably from 16 percent by weight to 30 percent by weight, more preferably from 18 percent by weight to 30 percent by weight, even more preferably from 20 percent by weight to 30 percent by weight.

For example, an overall content of hemicellulose in the plug element on a dry weight basis is from 15 percent by weight to 28 percent by weight, preferably from 16 percent by weight to 28 percent by weight, more preferably from 18 percent by weight to 28 percent by weight, even more preferably from 20 percent by weight to 28 percent by weight.

For example, an overall content of hemicellulose in the plug element on a dry weight basis is from 15 percent by weight to 26 percent by weight, preferably from 16 percent by weight to 26 percent by weight, more preferably from 18 percent by weight to 26 percent by weight, even more preferably from 20 percent by weight to 26 percent by weight.

For example, an overall content of hemicellulose in the plug element on a dry weight basis is from 15 percent by weight to 24 percent by weight, preferably from 16 percent by weight to 24 percent by weight, more preferably from 18 percent by weight to 24 percent by weight, even more preferably from 20 percent by weight to 24 percent by weight.

For example, an overall content of hemicellulose in the plug element on a dry weight basis is from 15 percent by weight to 22 percent by weight, preferably from 16 percent by weight to 22 percent by weight, more preferably from 18 percent by weight to 22 percent by weight, even more preferably from 20 percent by weight to 22 percent by weight.

The combined amount of exogenous lignin and exogenous hemicellulose in the additive coating is at least 10 percent by weight, more preferably at least 12 percent by weight, more preferably at least 14 percent by weight, more preferably at least 16 percent by weight, more preferably at least 18 percent by weight, on a dry weight basis.

The combined amount of exogenous lignin and exogenous hemicellulose in the additive coating is preferably up to 50 percent by weight, more preferably up to 45 percent by weight, more preferably up to 40 percent by weight, more preferably up to 35 percent by weight, more preferably up to 30 percent by weight, on a dry weight basis.

For example, the combined amount of exogenous lignin and exogenous hemicellulose in the additive coating may be between 10 percent by weight and 50 percent by weight, or between 12 percent by weight and 45 percent by weight, or between 14 percent by weight and 40 percent by weight, or between 16 percent by weight and 35 percent by weight, or between 18 percent by weight and 30 percent by weight, on a dry weight basis.

The combined amount of exogenous lignin and exogenous hemicellulose in the cellulosic filtration material is preferably at least 1 percent by weight, more preferably at least 1.5 percent by weight, more preferably at least 2 percent by weight, more preferably at least 2.5 percent by weight, on a dry weight basis.

The combined amount of exogenous lignin and exogenous hemicellulose in the cellulosic filtration material is preferably up to 10 percent by weight, more preferably up to 8 percent by weight, more preferably up to 6 percent by weight, more preferably up to 4 percent by weight, on a dry weight basis.

For example, the combined amount of exogenous lignin and exogenous hemicellulose in the cellulosic filtration material may be between 1 percent by weight and 10 percent by weight, or between 1.5 percent by weight and 8 percent by weight, or between 2 percent by weight and 6 percent by weight, or between 2.5 percent by weight and 4 percent by weight, on a dry weight basis.

Alternatively on in addition, the additive coating may further comprise at least one monosaccharide derivative or disaccharide derivative, for example, sucrose acetate iso-butyrate.

The at least one monosaccharide derivative or disaccharide derivative advantageously provides additional active functional groups, such as acetyl and carboxymethyl groups, that are particularly effective at scavenging phenols and other undesirable gaseous compounds generated from the aerosol-generating substrate. The inclusion of the additional monosaccharide derivative or disaccharide derivative in the additive coating, in addition to the lignin or lignin/polysaccharide mixture, therefore further reduces the level of phenols and other undesirable gaseous compounds in the mainstream aerosol as it passes through the downstream element from the aerosol-generating substrate.

The monosaccharide derivative or disaccharide derivative has also been found to advantageously improve the hydrophobicity of the cellulosic filtration material as well as the temperature stability.

Preferably, the additive coating comprises at least 20 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, more preferably at least 30 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, more preferably at least 40 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, more preferably at least 50 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, on a dry weight basis.

Preferably, the additive coating comprises up to 90 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, more preferably up to 85 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, more preferably up to 80 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, on a dry weight basis.

For example, the additive coating may comprise between 20 percent by weight and 90 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 30 percent by weight and 90 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 40 percent by weight and 90 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 50 percent by weight and 90 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 20 percent by weight and 85 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 30 percent by weight and 85 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 40 percent by weight and 85 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 50 percent by weight and 85 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 20 percent by weight and 80 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 30 percent by weight and 80 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 40 percent by weight and 80 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, or between 50 percent by weight and 80 percent by weight of the at least one monosaccharide derivative or disaccharide derivative, on a dry weight basis.

Alternatively or in addition, the additive coating may further comprise at least one cross-linking agent. The at least one cross-linking agent preferably provides effective cross-linking of the lignin and polysaccharide (where present).

The inclusion of at least one cross-linking agent therefore increases the viscosity of the additive coating such that it can be more readily applied to the fibres. The inclusion of the at least one cross-linking agent also improves the ability of the additive coating to bind the regenerated cellulose fibres of the fibrous material together. Advantageously, the inclusion of the at least one cross-linking agent may improve the hydrophobicity of the cellulosic filtration material as well as the temperature stability. Certain cross-linking agents may additionally provide active functional groups for scavenging of phenols and other undesirable gaseous compounds generated from the aerosol-generating substrate. This may further increase the reduction of the level of phenols and other undesirable gaseous compounds in the mainstream aerosol as it passes through the downstream element from the aerosol-generating substrate.

Suitable cross-linking agents include but are not limited to: acetic anhydride, succinic anhydride, pyridine, triacetin or combinations thereof.

Preferably, the additive coating comprises at least 0.1 percent by weight of the at least one cross-linking agent, more preferably at least 0.2 percent by weight of the at least one cross-linking agent, more preferably at least 0.3 percent by weight of the at least one cross-linking agent, more preferably at least 0.5 percent by weight of the at least one cross-linking agent, on a dry weight basis.

Preferably, the additive coating comprises up to 10 percent by weight of the at least one cross-linking agent, more preferably up to 15 percent by weight of the at least one cross-linking agent, more preferably up to 2 percent by weight of the at least one cross-linking agent, on a dry weight basis.

For example, the additive coating may comprise between 0.1 percent by weight and 10 percent by weight of the at least one cross-linking agent, or between 0.2 percent by weight and 10 percent by weight of the at least one cross-linking agent, or between 0.3 percent by weight and 10 percent by weight of the at least one cross-linking agent, or between 0.5 percent by weight and 10 percent by weight of the at least one cross-linking agent, or between 0.1 percent by weight and 5 percent by weight of the at least one cross-linking agent, or between 0.2 percent by weight and 5 percent by weight of the at least one cross-linking agent, or between 0.3 percent by weight and 5 percent by weight of the at least one cross-linking agent, or between 0.5 percent by weight and 5 percent by weight of the at least one cross-linking agent, between 0.1 percent by weight and 2 percent by weight of the at least one cross-linking agent, or between 0.2 percent by weight and 2 percent by weight of the at least one cross-linking agent, or between 0.3 percent by weight and 2 percent by weight of the at least one cross-linking agent, or between 0.5 percent by weight and 2 percent by weight of the at least one cross-linking agent, on a dry weight basis.

Preferably, the cellulosic filtration material comprises at least 0.001 percent by weight of the at least one cross-linking agent, more preferably at least 0.005 percent by weight of the at least one cross-linking agent, more preferably at least 0.01 percent of the at least one cross-linking agent, more preferably at least 0.02 percent of the at least one cross-linking agent, on a dry weight basis.

Preferably, the cellulosic filtration material comprises up to 3 percent by weight of the at least one cross-linking agent, more preferably up to 2 percent by weight of the at least one cross-linking agent, more preferably up to 11 percent by weight of the at least one cross-linking agent, more preferably up to 0.1 percent by weight of the at least one cross-linking agent, on a dry weight basis.

For example, the cellulosic filtration material may comprise between 0.001 and 3 percent by weight of the at least one cross-linking agent, or between 0.005 percent by weight and 2 percent by weight of the at least one cross-linking agent, or between 0.01 percent by weight and 0.1 percent by weight of the at least one cross-linking agent, or between 0.02 percent by weight and 0.05 percent by weight of the at least one cross-linking agent, on a dry weight basis.

In order to prepare the additive coating, the lignin is preferably combined with the other optional components of the additive coating and formed into a slurry with water. The slurry may be heated in order to bring about any desired reactions between the components of the additive coating.

The additive coating may be applied to the paper material in any suitable manner. Preferably, the additive coating is applied to the paper material prior to the paper material being formed into the plug element.

Thus, the present invention further provides a method for the production of a cellulosic filtration material for forming a plug element of a downstream element of an aerosol-generating article according to the invention, as described above. The method comprises the steps of: providing a paper material; forming an additive coating solution comprising at least 5 percent by weight of exogenous lignin, on a dry weight basis and optionally one or more polysaccharides in water; applying the additive coating solution to the paper material; forming a plug element comprising the coated paper material; and drying the coated paper material, wherein an overall content of lignin in the plug element is at least 2 percent by weight of the plug element.

The additive coating solution is formed by combining the dry ingredients of the additive coating and dispersing or dissolving them in water. The dry ingredients include exogenous lignin, optionally one or more polysaccharides and optionally one or more cross-linking agents, as described above. The additive coating solution may optionally be heated prior to application of the solution to the paper material, for example, in order to bring about any necessary reactions between the components of the additive coating.

For example, in the step of applying the additive coating solution to the paper material, the additive coating solution may be applied to the paper material (typically in sheet form) by known printing processes, such as gravure printing or flexographic printing, or by known coating processes, like curtain coating, reverse gravure, semi-flexo, rod-coating, blade coating, comma coating, slot die coating. These processes may advantageously enable the formation of a defined layer of additive coating on at least part of an external surface of one or both sides of the paper material.

The additive coating solution may also be applied to the paper material (typically in sheet form) by an impregnation process, such as by dipping the paper material into a bath of the additive coating solution or by spraying the additive coating solution onto the paper material, and letting the additive coating solution be at least partly absorbed into the paper material. Depending on how hydrophilic or hydrophobic the paper material is, the additive coating solution may permeate more or less deeply into the paper material or form more or less of a deposit of the additive coating on the external surface of at least one side of the paper material.

As an alternative, in the step of applying the additive coating solution to the paper material the additive coating solution may be applied to the paper material by injecting the additive coating solution into the plug element after the paper material has been processed and formed into a rod shape, or by dipping the formed plug element into a bath of the additive coating.

After the additive coating has been applied to the paper material, the thus treated paper material is preferably dried by any suitable means, including conventional heating, or microwave heating. Any curing of the additive coating may also be carried out during this drying step.

The step of drying the coated paper material, which may optionally comprise a curing of the coated paper material, may comprise heating the coated paper material using a conventional heater. Alternatively or in addition, the step of drying and optionally curing the coated paper material may comprise heating the coated paper material by microwave heating. The drying and optional curing of the additive coating solution is carried out in order to evaporate the water from the solution and to bring about curing of the additive coating or hardening of the additive coating or both.

Methods for forming a sheet of the paper material into rod-shaped plug element will be generally known to the skilled person, and may involve gathering or winding of the sheet material.

In aerosol-generating articles according to the present invention, the downstream element preferably comprises a plug element of the cellulosic filtration material described above circumscribed by a wrapper, for example a paper wrapper.

For example, a continuous web of paper material to which the additive coating has been applied (that is, a continuous web of treated paper material) may be drawn and passed between pairs of superimposed embossing or crimping rolls.

It is preferred that the resulting textured web of treated paper material is not moistened before being laterally gathered and compressed (such as by being fed into a forming cone such as the one utilized on cigarette making machines). Some existing manufacturing processes do involve a moistening step, wherein water is sprayed over a paper material for use in an aerosol-generating article. However, in the context of the present invention, such a moistening step is preferably avoided because the addition of water may recrystallise the cellulose in the paper material and thus reduce the ability of the plug element to absorb flue gases and phenols. A paper wrapper may be wound about the gathered and compressed web in the forming cone, and overlapping edges of the paper wrapper may be bound together by applying an adhesive to a first edge of the wrapper and thereafter folding the other edge into contact with the first edge. The overlapping edges of the paper wrapper may be bound together by a heated roller, which both removes liquid and sets the adhesive. The resulting rod may be cut into segments having a predetermined length by a rotary cutter.

The wrapper circumscribing the cellulosic filtration material may have a basis weight of at least 50 grams per square metre (gsm). Where the downstream element is positioned at the downstream end of the aerosol-generating article, this may help to provide a desired firmness for the aerosol-generating article. In certain embodiments, it may be desirable to use a stiff wrapper, for example, a wrapper having a basis weight of at least about 80 grams per square metre (gsm), or at least about 100 gsm, or at least about 110 gsm.

Preferably, the downstream element comprising the cellulosic filtration material has an average radial hardness of at least 75 percent, more preferably at least 80 percent, more preferably at least 85 percent. Preferably, the downstream element has a radial hardness of less than 100 percent, more preferably less than 95 percent. This can provide an aerosol-generating article having a downstream end with a satisfactory hardness for the consumer.

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

Radial ⁢ hardness ⁢ ( % ) = D d D S * 100 ⁢ %

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

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

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

As described above, the downstream element comprising the cellulosic filtration material advantageously provides improved biodegradability compared to conventional cellulose acetate segments.

Preferably, the downstream element is substantially free from cellulose acetate.

As described briefly above, the downstream element comprising the plug element is provided downstream of the aerosol-generating substrate and in axial alignment with the aerosol-generating substrate.

In some embodiments, the aerosol-generating article is formed essentially of an aerosol-generating 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 aerosol-generating 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 reducing undesirable compounds (for example, phenols) from the 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 preferred embodiments, the particulate phase filtration efficiency of the plug element is less than about 30 percent, more preferably less than about 20 percent.

In some embodiments, the mouthpiece element may have an RTD of less than or equal to about 25 millimetres H₂O, less than or equal to about 20 millimetres H₂O, or less than or equal to about 15 millimetres H₂O. In such embodiments, the mouthpiece element may have an RTD of at least about 10 millimetres H₂O.

The mouthpiece element may have an RTD of between about 10 millimetres H₂O and to about 25 millimetres H₂O, between about 10 millimetres H₂O and to about 20 millimetres H₂O, or of between about 10 millimetres H₂O and to about 15 millimetres H₂O.

Preferably, the mouthpiece element has a substantially circular cross-section.

Preferably, the mouthpiece element has an external diameter that is substantially the same as the external diameter of the aerosol-generating article.

A length of the mouthpiece may be at least about 3 millimetres, or at least about 5 millimetres.

The length of the mouthpiece element may be less than or equal to about 11 millimetres, or less than or equal to about 9 millimetres.

The length of the mouthpiece element may be between about 3 millimetres and about 11 millimetres, or between about 3 millimetres and about 9 millimetres.

The length of the mouthpiece element may be between about 5 millimetres and about 11 millimetres, or between about 5 millimetres and about 9 millimetres.

For example, the length of the mouthpiece element may be about 7 millimetres.

The length of the mouthpiece element may be selected based on a desired total length of the aerosol-generating article.

The mouthpiece element may be circumscribed by a plug wrap.

The mouthpiece element may be unventilated such that air does not enter the aerosol-generating article along the mouthpiece element.

The mouthpiece element may be connected to one or more adjacent components of the aerosol-generating article by means of a tipping wrapper.

The aerosol-generating article may define a mouth end cavity at the downstream end of the aerosol-generating article. For example, the mouthpiece element may itself be in the form of a hollow tubular element. As an alternative, the mouthpiece may include a non-hollow plug element as described above immediately upstream of a hollow tubular segment provided at the downstream end of the mouthpiece. As a further alternative, the mouth end cavity may be defined by an outer wrapper of the mouthpiece extending beyond a downstream end of a plug element as described above.

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 aerosol-generating 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 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 aerosol-generating article.

The aerosol-cooling element preferably has a low resistance to draw. That is, the aerosol-cooling element preferably offers a low resistance to the passage of air through the aerosol-generating article. Preferably, the aerosol-cooling element does not substantially affect the resistance to draw of the aerosol-generating article.

The aerosol-cooling element may comprise a plurality of longitudinally extending channels. The plurality of longitudinally extending channels may be defined by a sheet of paper material that has been one or more of crimped, pleated, gathered and folded to form the channels. The plurality of longitudinally extending channels may be defined by a single sheet that has been one or more of crimped, pleated, gathered and folded to form multiple channels. Alternatively, the plurality of longitudinally extending channels may be defined by multiple sheets that have been one or more of crimped, pleated, gathered and folded to form multiple channels.

For example, the aerosol-cooling element may be formed from a gathered sheet of paper material having a specific surface area of between approximately 10 square millimetres per milligram and approximately 100 square millimetres per milligram. In some embodiments, the aerosol-cooling element may be formed from a gathered sheet of paper material having a specific surface area of approximately 35 square mm per milligram.

At least one of the support element and the aerosol-cooling element may be in the form of a hollow tubular element. In some embodiments, both the support element and the aerosol-cooling element are in the form of hollow tubular elements, which may differ in length, internal diameter or both.

In an aerosol-generating article in accordance with the present invention, such a hollow tubular element provides an unrestricted flow channel. This means that the hollow tubular element provides a negligible level of RTD. As used herein with reference to the invention, the term “negligible level of RTD” is used to describe an RTD of less than 1 mm H₂O per 10 millimetres of length of the hollow tubular substrate element, less than 0.4 mm H₂O per 10 millimetres of length of the hollow tubular substrate element, or less than 0.1 mm H₂O per 10 millimetres of length of the hollow tubular substrate element. The flow channel should therefore be free from any components that would obstruct the flow of air in a longitudinal direction. Preferably, the flow channel is substantially empty.

The hollow tubular element may have a total length of at least about 10 millimetres, at least about 12 millimetres, or at least about 15 millimetres.

The hollow tubular element may have a total length of less than or equal to about 30 millimetres, less than or equal to about 25 millimetres, or less than or equal to about 23 millimetres.

The hollow tubular element may have a total length of between about 10 millimetres and about 30 millimetres, between about 10 millimetres and about 25 millimetres, or between about 10 millimetres and about 23 millimetres. The hollow tubular element may have a total length of between about 12 millimetres and about 30 millimetres, between about 12 millimetres and about 25 millimetres, or between about 12 millimetres and about 23 millimetres. The hollow tubular element may have a total length of between about 12 millimetres and about 30 millimetres, between about 12 millimetres and about 25 millimetres, or between about 12 millimetres and about 23 millimetres.

The total length of the hollow tubular element may be selected based on a desired total length of the aerosol-generating article.

In some embodiments, a ventilation zone may be provided at a location downstream of the aerosol-generating substrate.

By way of example, cooling of a stream of smoke generated upon combusting the aerosol-generating substrate may be achieved by providing a ventilation zone at a location along a mouthpiece of the aerosol-generating article.

As another example, a satisfactory cooling of the stream of aerosol generated upon heating the aerosol-generating substrate and drawn through a hollow tubular element as described above may be achieved by providing a ventilation zone at a location along the hollow tubular element itself. Without wishing to be bound by theory, the temperature drop caused by the admission of cooler, external air into the aerosol-generating article downstream of the aerosol-generating element via the ventilation zone may have an advantageous effect on the nucleation and growth of aerosol particles.

The ventilation zone may comprise a plurality of perforations, for example provided through a tubular wall of the hollow tubular element. The ventilation zone may comprise at least one circumferential row of perforations. The ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed online during manufacturing of the aerosol-generating article. Each circumferential row of perforations may comprise from 8 to 30 perforations.

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.

In some embodiments, the aerosol-generating article comprises an upstream section located upstream of the aerosol-generating substrate. The upstream section is preferably located immediately upstream of the aerosol-generating substrate. The upstream section preferably extends from an upstream end of the aerosol-generating article to an upstream end of the aerosol-generating substrate. The upstream section preferably comprises an upstream element located immediately upstream of the rod of aerosol-generating substrate.

Where the aerosol-generating substrate comprises shredded tobacco, such as tobacco cut filler, the upstream section or element thereof may additionally help to prevent the loss of loose particles of tobacco from the upstream end of the article.

The upstream section, or upstream element thereof, may also additionally provide a degree of protection to the aerosol-generating substrate during storage, as it covers at least to some extent the upstream end of the aerosol-generating substrate, which may otherwise be exposed. For aerosol-generating articles that are intended to be inserted into a cavity in an aerosol-generating device such that the aerosol-generating substrate can be externally heated within the cavity, the upstream section, or upstream element thereof, may advantageously facilitate the insertion of the upstream end of the article into the cavity.

An upstream element of the upstream section may be made of any material suitable for use in an aerosol-generating article. The upstream element may, for example, be made of a same material as used for one of the other components of the aerosol-generating article, such as the mouthpiece, the aerosol-cooling element or the support element, the geometry and function of which have been described above. Suitable materials for forming the upstream element include filter materials, ceramic, polymer material, cellulose acetate, cardboard, zeolite or aerosol-generating substrate.

In preferred embodiments, the upstream element may comprise a plug element comprising a cellulosic filtration material comprising a paper material and an additive coating applied to the paper material, the additive coating comprising at least 5 percent by weight of exogenous lignin on a dry weight basis, an overall content of lignin in the plug element being at least 2 percent by weight of the plug element.

For example, the upstream element may be formed of the same cellulosic filtration material as the downstream element described above. From an environmental perspective, this is advantageous in that a greater portion of the aerosol-generating article as a whole is more readily degradable. Additionally, from a manufacturing viewpoint, it is advantageous to form different components of a same aerosol-generating article of the same material, as it will generally require less adjustments to the settings of existing apparatus.

Preferably, the upstream section, or an upstream element thereof, has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. Preferably, the external diameter of the upstream section, or an upstream element thereof, is between about 6 millimetres and about 8 millimetres, more preferably between about 7 millimetres and about 7.5 millimetres. Preferably, the upstream section or an upstream element has an external diameter that is about 7.1 mm.

Preferably, the upstream section or an upstream element has a length of between about 2 millimetres and about 8 millimetres, more preferably between about 3 millimetres and about 7 millimetres, more preferably between about 4 millimetres and about 6 millimetres. In a particularly preferred embodiment, the upstream section or an upstream element has a length of about 5 millimetres. The length of the upstream section or an upstream element can advantageously be varied in order to provide the desired total length of the aerosol-generating article.

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

The upstream section is preferably connected to the rod of aerosol-generating substrate and optionally at least a part of the downstream section by means of an outer wrapper.

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 aerosol-generating article preferably has an overall length of from 40 millimetres to 80 millimetres, or from 40 millimetres to about 70 millimetres, or from 40 millimetres to about 60 millimetres, or from 45 millimetres to about 80 millimetres, or from about 45 millimetres to about 70 millimetres, or from 45 millimetres to 60 millimetres, or from 50 millimetres to 80 millimetres, or from 50 millimetres to about 70 millimetres or from about 50 millimetres to about 60 millimetres. In an exemplary embodiment, an overall length of the aerosol-generating article is about 45 millimetres.

Preferably, the aerosol-generating article has a substantially circular cross-section.

The aerosol-generating article preferably has an external diameter of from about 5 millimetres to about 12 millimetres, or from about 6 millimetres to about 12 millimetres, or from about 7 millimetres to about 12 millimetres, or from about 5 millimetres to about 10 millimetres, or from about 6 millimetres to about 10 millimetres, or from about 7 millimetres to about 10 millimetres, or from about 5 millimetres to about 8 millimetres, or from about 6 millimetres to about 8 millimetres, or from about 7 millimetres to about 8 millimetres. In other embodiments, the aerosol-generating article has an external diameter of less than 7 millimetres.

The overall RTD of the aerosol-generating article is preferably at least 10 millimetres H₂O, more preferably at least 15 millimetres H₂O, more preferably at least 20 millimetres H₂O, more preferably at least 25 millimetres H₂O, more preferably at least 30 millimetres H₂O.

The overall RTD of the aerosol-generating article is preferably no more than 70 millimetres H₂O, more preferably no more than 60 millimetres H₂O, more preferably no more than 55 millimetres H₂O, more preferably no more than 50 millimetres H₂O, more preferably no more than 45 millimetres H₂O.

For example, the overall RTD of the aerosol-generating article may be between 10 millimetres H₂O and 70 millimetres H₂O, or between 15 millimetres H₂O and 60 millimetres H₂O, or between 20 millimetres H₂O and 55 millimetres H₂O, or between 25 millimetres H₂O and 45 millimetres H₂O, or between 30 millimetres H₂O and 45 millimetres H₂O.

As described above, an aerosol-generating article in accordance with the present invention comprises an aerosol-generating substrate. In several embodiments, the aerosol-generating article comprises a rod of aerosol-generating substrate circumscribed by a rod plug wrap.

Preferably, the rod of aerosol-generating substrate has a length of at least 8 millimetres, more preferably a length of at least 9 millimetres, more preferably a length of at least 10 millimetres. Preferably, the length of the rod of aerosol-generating substrate is less than 16 millimetres, more preferably less than 15 millimetres, more preferably less than 14 millimetres. For example, the rod of aerosol-generating substrate may have a length of between 8 millimetres and 16 millimetres, or between 9 millimetres and 15 millimetres, or between 10 millimetres and 14 millimetres. In a particularly preferred embodiment, the rod of aerosol-generating substrate has a length of about 12 millimetres.

Preferably, the ratio between the length of the rod of aerosol-generating substrate and the overall length of the aerosol-generating article is at least 0.10, more preferably at least 0.15, more preferably at least 0.20, more preferably at least 0.25. Preferably, the ratio between the length of the rod of aerosol-generating substrate and the overall length of the aerosol-generating article is less than 0.50, more preferably less than 0.45, more preferably less than 0.40, more preferably less than 0.35. For example, the ratio between the length of the rod of aerosol-generating substrate and the overall length of the aerosol-generating article may be between 0.1 and 0.5, or between 0.15 and 0.45, or between 0.2 and 0.4, or between 0.25 and 0.35.

Preferably, the rod of aerosol-generating substrate has an external diameter that is approximately equal to the external diameter of the aerosol-generating article.

Preferably, the rod of aerosol-generating substrate has an external diameter of at least 5 millimetres, more preferably at least 6 millimetres, more preferably at least 7 millimetres. Preferably, the rod of aerosol-generating substrate has an external diameter of less than 12 millimetres, more preferably less than 10 millimetres, more preferably less than 8 millimetres. For example, the external diameter may be between 5 millimetres and 12 millimetres, or between 6 millimetres and 10 millimetres, or between 7 millimetres and 8 millimetres. In a particularly preferred embodiment, the rod of aerosol-generating substrate has an external diameter of about 7.1 millimetres.

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

The aerosol-generating substrate may have a density of at least about 150 milligrams per cubic centimetre, at least about 175 milligrams per cubic centimetre, at least about 200 milligrams per cubic centimetre, or at least about 250 milligrams per cubic centimetre.

The aerosol-generating substrate may have a density of less than or equal to about 500 milligrams per cubic centimetre, less than or equal to about 450 milligrams per cubic centimetre, less than or equal to about 400 milligrams per cubic centimetre, or less than or equal to about 350 milligrams per cubic centimetre.

The RTD of the rod of aerosol-generating substrate may be at least about 4 millimetres H₂O, at least about 5 millimetres H₂O, or at least about 6 millimetres H₂O.

The RTD of the rod of aerosol-generating substrate may be less than or equal to about 10 millimetres H₂O, less than or equal to about 9 millimetres H₂O, or less than or equal to about 8 millimetres H₂O.

The aerosol-generating substrate may be a solid aerosol-generating substrate. Suitable types of materials for use in the aerosol-generating substrate are described below and include, for example, tobacco cut filler, homogenised tobacco material such as cast leaf, aerosol-generating films and gel compositions.

The aerosol-generating substrate preferably comprises an aerosol former. Suitable aerosol formers are for example: polyhydric alcohols such as, for example, triethylene glycol, 1,3-butanediol, propylene glycol and glycerine; esters of polyhydric alcohols such as, for example, glycerol mono-, di- or triacetate; aliphatic esters of mono-, di- or polycarboxylic acids such as, for example, dimethyl dodecanedioate and dimethyl tetradecanedioate; and combinations thereof.

Preferably, the aerosol former comprises one or more of glycerine and propylene glycol. The aerosol former may consist of glycerine or propylene glycol or of a combination of glycerine and propylene glycol.

In certain embodiments, the aerosol-generating substrate preferably comprises at least 5 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably at least 10 percent by weight on a dry weight basis, more preferably at least 15 percent by weight on a dry weight basis. In such embodiments, the aerosol-generating substrate preferably comprises no more than 30 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably no more than 25 percent by weight on a dry weight basis, more preferably no more than 20 percent by weight on a dry weight basis. For example, the aerosol former content of the aerosol-generating substrate may be between 5 percent and 30 percent by weight, or between 10 percent and 25 percent by weight, or between about 15 percent and about 20 percent by weight, on a dry weight basis. In such embodiments, the aerosol former content is therefore relatively low.

In other embodiments, the aerosol-generating substrate preferably comprises at least 40 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably at least 45 percent by weight on a dry weight basis, more preferably at least 50 percent by weight on a dry weight basis. In such embodiments, the aerosol-generating substrate preferably comprises no more than 80 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably no more than 75 percent by weight on a dry weight basis, more preferably no more than 70 percent by weight on a dry weight basis. For example, the aerosol former content of the aerosol-generating substrate may be between 40 percent and 80 percent by weight, or between 45 percent and 75 percent by weight, or between about 50 percent and about 70 percent by weight, on a dry weight basis. In such embodiments, the aerosol former content is therefore relatively high.

In some preferred embodiments, the aerosol-generating substrate comprises tobacco material. For example, the aerosol-generating substrate may comprise shredded tobacco material. For example, the shredded tobacco material may be in the form of cut filler, as described in more detail below. Alternatively, the shredded tobacco material may be in the form of a shredded sheet of homogenised tobacco material. Suitable homogenised tobacco materials for use in the present invention are described below.

Within the context of the present specification, the term “cut filler” is used to describe to a blend of shredded plant material, such as tobacco plant material, including, in particular, one or more of leaf lamina, processed stems and ribs, homogenised plant material.

The cut filler suitable to be used with the present invention generally may resemble cut filler used for conventional smoking articles. The cut width of the cut filler preferably may be between 0.3 millimetres and 2.0 millimetres, or between 0.5 millimetres and 1.2 millimetres, or between 0.6 millimetres and 0.9 millimetres.

Preferably, the strands have a length of between about 10 millimetres and about 40 millimetres before the strands are collated to form the rod of aerosol-generating substrate.

Preferably, the cut filler is soaked with the aerosol former. Soaking the cut filler can be done by spraying or by other suitable application methods. Preferably, the aerosol former in the cut filler comprises one or more of glycerol and propylene glycol. The aerosol former may consist of glycerol or propylene glycol or of a combination of glycerol and propylene glycol.

In other preferred embodiments, the aerosol-generating substrate comprises homogenised plant material, preferably a homogenised tobacco material.

As used herein, the term “homogenised plant material” encompasses any plant material formed by the agglomeration of particles of plant. For example, sheets or webs of homogenised tobacco material for the aerosol-generating substrates of the present invention may be formed by agglomerating particles of tobacco material obtained by pulverising, grinding or comminuting plant material and optionally one or more of tobacco leaf lamina and tobacco leaf stems. The homogenised plant material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

The homogenised plant material can be provided in any suitable form.

In some embodiments, the homogenised plant material may be in the form of one or more sheets. As used herein with reference to the invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.

The homogenised plant material may be in the form of a plurality of pellets or granules.

The homogenised plant material may be in the form of a plurality of strands, strips or shreds. As used herein, the term “strand” describes an elongate element of material having a length that is substantially greater than the width and thickness thereof.

The aerosol former content of the homogenised tobacco material is preferably within the ranges defined above for aerosol-generating substrate having a relatively low aerosol former content.

In other preferred embodiments, the aerosol-generating substrate is in the form of an aerosol-generating film comprising a cellulosic based film-forming agent, nicotine and the aerosol former. The aerosol-generating film may further comprise a cellulose based strengthening agent. The aerosol-generating film may further comprise water, preferably 30 percent by weight of less of water.

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

In the context of the present invention the term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film. Preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methyl cellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof. In particularly preferred embodiments, the cellulose based film-forming agent is HPMC.

The aerosol former content of the aerosol-generating film is within the ranges defined above for aerosol-generating substrates having a relatively high aerosol former content.

Suitable aerosol-generating films for use as the aerosol-generating substrate of aerosol-generating articles according to the invention are described in WO-A-2020/207733 and WO-A-2022/074157.

Preferably, the aerosol-generating film comprises between 0.5 percent and 10 percent by weight of nicotine, or between 1 percent and 8 percent by weight of nicotine, or between 2 percent and 6 percent by weight of nicotine, on a dry weight basis.

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

In alternative embodiments of the invention, the aerosol-generating substrate may comprise a gel composition that includes nicotine, at least one gelling agent and the aerosol former. The gel composition is preferably substantially tobacco free.

The preferred weight ranges for nicotine in the gel composition are the same as those defined above in relation to aerosol-generating films.

Suitable gel compositions for use as the aerosol-generating substrate of aerosol-generating articles according to the invention are described in WO-A-2021/170642.

The gel composition preferably comprises at least 50 percent by weight of aerosol former, more preferably at least 60 percent by weight, more preferably at least 70 percent by weight of aerosol former, on a dry weight basis. The gel composition may comprise up to 80 percent by weight of aerosol former. The aerosol former in the gel composition is preferably glycerol.

In certain embodiments of the invention, the aerosol-generating article further comprises one or more elongate susceptor elements within the rod of aerosol-generating substrate. For example, one or more elongate susceptor elements may be arranged substantially longitudinally within the rod of aerosol-generating substrate and in thermal contact with the aerosol-generating substrate.

As used herein with reference to the present invention, the term “susceptor element” refers to a material that can convert electromagnetic energy into heat.

Suitable susceptor elements for use in the aerosol-generating substrate of aerosol-generating articles according to the present invention are described in WO-A-2021/170673.

Preferably, the rod of aerosol-generating substrate is circumscribed by a wrapper. The wrapper may be a paper wrapper or a non-paper wrapper.

Suitable paper wrappers for use in specific embodiments of the invention are known in the art and include, but are not limited to: cigarette papers; and filter plug wraps. Suitable non-paper wrappers for use in specific embodiments of the invention are known in the art and include, but are not limited to sheets of homogenised tobacco materials.

According to a second aspect of the present invention, there is provided an aerosol-generating system comprising: an aerosol-generating article according to the first aspect of the invention; and an aerosol-generating device configured to heat the aerosol-generating substrate of the aerosol-generating article.

The aerosol-generating device comprises means for heating the aerosol-generating substrate to a temperature sufficient to generate an aerosol from the aerosol-generating substrate. Preferably, the aerosol-generating device comprises a housing defining a cavity configured to receive the aerosol-generating article, and means for heating the aerosol-generating substrate to a temperature sufficient to generate an aerosol from the aerosol-generating substrate when the aerosol-generating article is received within the cavity.

The aerosol-generating device may be a handheld aerosol-generating device.

The aerosol-generating device may be an electrically-operated aerosol-generating device.

The aerosol-generating device may comprise a power supply and control electronics.

The aerosol-generating device may comprise a battery and control electronics.

The aerosol-generating device may be configured to heat the aerosol-generating substrate internally. That is, the aerosol-generating device may be configured to supply heat to the aerosol-generating substrate from a location internal to the aerosol-generating article.

For example, in some embodiments the aerosol-generating device comprises a heater element configured to be inserted into the aerosol-generating element when the aerosol-generating article is received within the cavity of the aerosol-generating device.

In other embodiments, the aerosol-generating article comprises a susceptor element provided at a location within the aerosol-generating element, and the aerosol-generating device comprises an inductor coil positioned on or within the housing, a power supply of the aerosol-generating device being connected to the inductor coil and configured to provide a high frequency oscillating current to the inductor coil. This generates an alternating magnetic field that induces a voltage in the susceptor element. The induced voltage causes a current to flow in the susceptor element, and this current causes Joule heating of the susceptor element that, in turn, heats the aerosol-generating substrate. The aerosol-generating device may be capable of generating a fluctuating electromagnetic field having a magnetic field strength (H-field strength) of between 1 and 5 kilo amperes per metre (kA m), preferably between 2 and 3 kA/m, for example about 2.5 kA/m.

The aerosol-generating device may be configured to heat the aerosol-generating substrate externally. That is, the aerosol-generating device may be configured to supply heat to the aerosol-generating substrate from a location external to the aerosol-generating article. For example, in some embodiments the aerosol-generating device comprises a heater element located about a perimeter of the cavity and configured to heat the aerosol-generating substrate of the aerosol-generating article from an exterior of the aerosol-generating element of the aerosol-generating article.

Examples will now be further described with reference to the drawings of the accompanying Figures in which:

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

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

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

The aerosol-generating article 1000 shown in FIG. 1 comprises an aerosol-generating element 1002 in the form of a substantially cylindrical rod 1004 of shredded tobacco circumscribed by a wrapper 1006. Further, the aerosol-generating article 1000 comprises a substantially cylindrical mouthpiece 1008 comprising a segment 1010 of a cellulosic filtration material circumscribed by a plug wrap 1012.

The mouthpiece 1008 is attached to the aerosol-generating element 1002 by a band 1014 of tipping paper. Perforations 1016 formed through the tipping paper and the plug wrap are provided to enable admission of ventilation air into the segment 1010 when the consumer draws upon the mouthpiece 1008 during use. The aerosol-generating article 1000 has a length of 70 millimetres and an external diameter of 7.6 millimetres.

The segment 1010 is in the form of a plug element comprising paper material and an additive coating applied to the paper material, the additive coating comprising at least 5 percent by weight of exogenous lignin on a dry weight basis.

The aerosol-generating article 10 shown in FIG. 2 comprises a rod 12 of aerosol-generating substrate 12 and a downstream section 14 at a location downstream of the rod 12 of aerosol-generating substrate. Further, the aerosol-generating article 10 comprises an upstream section 16 at a location upstream of the rod 12 of aerosol-generating substrate. Thus, the aerosol-generating article 10 extends from an upstream or distal end 18 to a downstream or mouth end 20, and has an overall length of about 45 millimetres.

The downstream section 14 comprises a support element 22 located immediately downstream of the rod 12 of aerosol-generating substrate, the support element 22 being in longitudinal alignment with the rod 12. In the embodiment of FIG. 2, the upstream end of the support element 18 abuts the downstream end of the rod 12 of aerosol-generating substrate. In addition, the downstream section 14 comprises an aerosol-cooling element 24 located immediately downstream of the support element 22, the aerosol-cooling element 24 being in longitudinal alignment with the rod 12 and the support element 22. In the embodiment of FIG. 1, the upstream end of the aerosol-cooling element 24 abuts the downstream end of the support element 22. In the embodiment of FIG. 2, the support element 22 and the aerosol-cooling element 24 together define an intermediate hollow section 50 of the aerosol-generating article 10.

The support element 22 comprises a first hollow tubular segment 26. The first hollow tubular segment 26 is provided in the form of a hollow cylindrical tube made of filtration material. The first hollow tubular segment 26 defines an internal cavity 28 that extends all the way from an upstream end 30 of the first hollow tubular segment to an downstream end 32 of the first hollow tubular segment 20. The internal cavity 28 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 28.

The first hollow tubular segment 26 has a length of about 8 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter of about 1.9 millimetres. Thus, a thickness of a peripheral wall of the first hollow tubular segment 26 is about 2.67 millimetres.

The aerosol-cooling element 24 comprises a second hollow tubular segment 34. The second hollow tubular segment 34 is provided in the form of a hollow cylindrical tube made of filtration material. The second hollow tubular segment 34 defines an internal cavity 36 that extends all the way from an upstream end 38 of the second hollow tubular segment to a downstream end 40 of the second hollow tubular segment 34. The internal cavity 36 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 36.

The second hollow tubular segment 34 has a length of about 8 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter of about 3.25 millimetres. Thus, a thickness of a peripheral wall of the second hollow tubular segment 34 is about 2 millimetres. Thus, a ratio between the internal diameter of the first hollow tubular segment 26 and the internal diameter of the second hollow tubular segment 34 is about 0.75.

The aerosol-generating article 10 comprises a ventilation zone 60 provided at a location along the second hollow tubular segment 34. In more detail, the ventilation zone is provided at about 2 millimetres from the upstream end of the second hollow tubular segment 34. A ventilation level of the aerosol-generating article 10 is about 25 percent.

In the embodiment of FIG. 2, the downstream section 14 further comprises a mouthpiece element 42 at a location downstream of the intermediate hollow section 50. In more detail, the mouthpiece element 42 is positioned immediately downstream of the aerosol-cooling element 24. As shown in the drawing of FIG. 2, an upstream end of the mouthpiece element 42 abuts the downstream end 40 of the aerosol-cooling element 18.

The mouthpiece element 42 is provided in the form of a cylindrical plug element 44 comprising paper material and an additive coating applied to the paper material, the additive coating comprising at least 5 percent by weight of exogenous lignin on a dry weight basis.

The mouthpiece element 42 has a length of about 12 millimetres and an external diameter of about 7.25 millimetres.

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

The rod 12 of aerosol-generating substrate has an external diameter of about 7.25 millimetres and a length of about 12 millimetres.

The aerosol-generating article 10 further comprises an elongate susceptor 46 within the rod 12 of aerosol-generating substrate. In more detail, the susceptor 46 is arranged substantially longitudinally within the aerosol-generating substrate, such as to be approximately parallel to the longitudinal direction of the rod 12. As shown in the drawing of FIG. 2, the susceptor 46 is positioned in a radially central position within the rod and extends effectively along the longitudinal axis of the rod 12. In more detail, the susceptor 46 is in thermal contact with the aerosol-generating substrate. The susceptor 46 extends all the way from an upstream end to a downstream end of the rod 12. In effect, the susceptor 46 has substantially the same length as the rod 12 of aerosol-generating substrate.

In more detail, in the embodiment of FIG. 2, the susceptor 46 is provided in the form of a strip and has a length of about 12 millimetres, a thickness of about 60 micrometres, and a width of about 4 millimetres.

The upstream section 16 comprises an upstream element 48 located immediately upstream of the rod 12 of aerosol-generating substrate, the upstream element 48 being in longitudinal alignment with the rod 12. In the embodiment of FIG. 2, the downstream end of the upstream element 48 abuts the upstream end of the rod 12 of aerosol-generating substrate. This advantageously prevents the susceptor 46 from being dislodged. Further, this ensures that the consumer cannot accidentally contact the heated susceptor 46 after use.

The upstream element 48 comprises a segment of material 50 in the form of a cylindrical plug of filtration material and a first wrapper 52 circumscribing the segment of material 50. The segment of material 50 has a length of about 5 millimetres. The RTD of the segment of material 50 is about 30 millimetres H₂O.

The aerosol-generating article 10 further comprises a combining wrapper 54 which attaches the upstream element 48 to the remaining components of the aerosol-generating article. In the embodiment of FIG. 2 a single combining wrapper 54 is depicted, which circumscribes and holds together the upstream element 48, the rod 12, and the downstream section 14 to form the aerosol-generating article.

However, it will be clear that alternative configurations are possible, wherein two or more combining wrappers are employed to assemble the different components of the aerosol-generating article. For example, a first combining wrapper could be used to attach the support element 22 to the aerosol-cooling element 24, and the resulting assembly could then be attached by means of a second combining wrapper to the upstream section 16 and the rod 12. The resulting combination of components could then be attached to the mouthpiece element 42 by means of a tipping wrapper. As shown in the drawing of FIG. 1, the aerosol-generating article 10 further comprises a wrapper 70 circumscribing the rod 12 of aerosol-generating substrate. The wrapper 70 is separate and distinct from the first wrapper 52 circumscribing the segment of material 50. Neither one of the first wrapper 52 and the wrapper 70 comprises a metallic foil.

In the aerosol-generating article 10 of FIG. 2, one or more of the first hollow tubular segment 26 of the support element 22, the second hollow tubular segment 34 of the aerosol-cooling element 24, and the segment of material 50 of the upstream element 48 may be made of the same material according to the present invention used in the mouthpiece element 42.

The aerosol-generating article 100 shown in FIG. 3 comprises a rod of aerosol-generating substrate 112 and a downstream section 114 at a location downstream of the rod 112 of aerosol-generating substrate. Additionally, the aerosol-generating article 100 comprises an upstream section 116. Thus, the aerosol-generating article 100 extends from an upstream or distal end 118—which substantially coincides with an upstream end of the upstream section 116—to a downstream or mouth end 120, which coincides with a downstream end of the downstream section 114. The downstream section 114 comprises a hollow tubular element 122 and a mouthpiece element 150. The upstream section 116 comprises an upstream plug element 124.

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

The rod of aerosol-generating substrate 112 comprises a shredded tobacco material. The rod of aerosol-generating substrate 112 comprises 150 milligrams of a shredded tobacco material comprising from 13 percent by weight to 16 percent by weight of glycerine. The density of the aerosol-generating substrate is about 300 mg per cubic centimetre. The RTD of the rod of aerosol-generating substrate 112 is between about 6 to 8 mm H₂O. The rod of aerosol-generating substrate 112 is individually wrapped by a plug wrap (not shown).

The hollow tubular element 122 is located immediately downstream of the rod 112 of aerosol-generating substrate, the hollow tubular element 122 being in longitudinal alignment with the rod 112. The upstream end of the hollow tubular element 122 abuts the downstream end of the rod 112 of aerosol-generating substrate.

The hollow tubular element 122 defines a hollow section of the aerosol-generating article 110. The hollow tubular element 122 does not substantially contribute to the overall RTD of the aerosol-generating article. In more detail, an RTD of the hollow tubular element 122 is about 0 mm H₂O.

As shown in FIG. 3, the hollow tubular element 122 is provided in the form of a hollow cylindrical tube made of cardboard. The hollow tubular element 122 defines an internal cavity that extends all the way from an upstream end of the hollow tubular element 122 to a downstream end of the hollow tubular element 122. The internal cavity is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity.

The hollow tubular element 122 has a length of about 21 millimetres, an external diameter of about 7.2 millimetres, and an internal diameter of about 6.7 millimetres. Thus, a thickness of a peripheral wall of the hollow tubular element 122 is about 0.25 millimetres.

The aerosol-generating article 100 comprises a ventilation zone 160 provided at a location along the hollow tubular element 122. The ventilation zone 160 comprises a circumferential row of openings or perforations circumscribing the hollow tubular element 122. The perforations of the ventilation zone 160 extend through the wall of the hollow tubular element 122, in order to allow fluid ingress into the internal cavity from the exterior of the article 100. A ventilation level of the aerosol-generating article 10 is about 16 percent.

On top of a rod 112 of aerosol-generating substrate and a downstream section 14 at a location downstream of the rod 12, the aerosol-generating article 100 comprises an upstream section 140 at a location upstream of the rod 112. As such, the aerosol-generating article 10 extends from a distal end 116 substantially coinciding with an upstream end of the upstream section 140 to a mouth end or downstream end 118 substantially coinciding with a downstream end of the downstream section 114.

As described briefly above, the upstream section 116 comprises an upstream plug element 124 located immediately upstream of the rod 112 of aerosol-generating substrate, the upstream plug element 124 being in longitudinal alignment with the rod 112. The downstream end of the upstream plug element 124 abuts the upstream end of the rod 112 of aerosol-generating substrate. The upstream plug element 124 is provided in the form of a hollow cylindrical plug of filtration material having a wall thickness of about 1 mm and defining an upstream internal cavity. The upstream element 124 has a length of about 5 millimetres. An external diameter of the upstream plug element 124 is about 7.1 mm. An internal diameter of the upstream plug element 42 is about 5.1 mm.

The mouthpiece element 150 extends from the downstream end of the hollow tubular element 122 to the downstream or mouth end of the aerosol-generating article 100. The mouthpiece element 150 has a length of about 7 mm. An external diameter of the mouthpiece element 150 is about 7.2 mm.

The mouthpiece element 150 is provided in the form of a cylindrical plug element comprising paper material and an additive coating applied to the paper material, the additive coating comprising at least 5 percent by weight of exogenous lignin on a dry weight basis.

In the aerosol-generating article 100 of FIG. 3, the plug element 124 of the upstream section 116 may be made of the same material according to the present invention used in the mouthpiece element 150.

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 ±5% 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.