WO2019030274A1

WO2019030274A1 - Aerosol-generating article having rod with multiple transverse sheets of tobacco material

Info

Publication number: WO2019030274A1
Application number: PCT/EP2018/071485
Authority: WO
Inventors: Tony Reevell
Original assignee: Philip Morris Products S.A.
Priority date: 2017-08-09
Filing date: 2018-08-08
Publication date: 2019-02-14

Abstract

A heated aerosol-generating article (10) comprises a rod of aerosol-generating substrate (12) comprising: a plurality of sheets of homogenised tobacco material (30,130) stacked such that each sheet (30,130) extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article (10), wherein the sheets are adapted to allow a flow of air in a longitudinal direction through the rod during use; and a wrapper (32,132) circumscribing the plurality of sheets (30,130). When the sheets are not transverse, the angle refers to the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross-section of the aerosol-generating article.

Description

AEROSOL-GENERATING ARTICLE HAVING ROD WITH MULTIPLE TRANSVERSE

SHEETS OF TOBACCO MATERIAL

The present invention relates to a heated aerosol-generating article comprising a rod of aerosol-generating substrate formed of a plurality of transverse sheets of homogenised tobacco material, and to a method for the production of such a rod of aerosol-generating substrate.

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

A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol- generating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article.

Substrates for heated aerosol-generating articles have, in the past, typically been produced using randomly oriented shreds, strands, or strips of tobacco material. The formation of rods for heated smoking or aerosol-generating articles from shreds of tobacco material suffers from a number of disadvantages. For example, the process of shredding tobacco material undesirably generates tobacco fines and other waste. Rods comprising shreds of tobacco material may exhibit "loose ends", that is, a loss of shreds of tobacco material from the ends of the rods. Rods comprising shreds of tobacco material may exhibit high standard deviations in weight, partially due to the tendency of rods to exhibit loose ends. Also, rods comprising shreds of tobacco material tend to exhibit non-uniform densities, that is, the density along the length of the rod tends to be inconsistent due to variations in the quantity of tobacco material at different locations along the rod. Furthermore, loose ends may disadvantageously lead to the need for more frequent cleaning of an aerosol-generating device for use with the aerosol-generating article and of manufacturing equipment.

International patent application WO-A-2012/164009 discloses rods for heated aerosol- generating articles formed from gathered sheets of tobacco material. The rods disclosed in WO- A-2012/164009 have a longitudinal porosity that allows air to be drawn through the rods. Effectively, folds in the gathered sheets of tobacco material define longitudinal channels through the rod. The use of rods formed from gathered sheets of homogenised tobacco material addresses some of the problems associated with forming an aerosol-generating substrate from shredded tobacco. However, such sheets typically have a relatively low tensile strength and so the gathering of the sheets to form the rods can have drawbacks.

It would be desirable to provide a homogenised tobacco rod for an aerosol-generating article which has a consistent tobacco distribution and porosity throughout the rod and which does not require the handling of a continuous web of homogenised tobacco material during production. It would be further desirable to provide such a homogenised tobacco rod that facilitates insertion of a heater element into the rod during use and that optimises the heat transfer from the heater element through the tobacco material within the rod. It would be particularly desirable to provide such a homogenised tobacco rod that can be manufactured efficiently and at relatively high speed.

According a first aspect of the present invention, there is provided a heated aerosol- generating article comprising a rod of aerosol-generating substrate, wherein the rod of aerosol- generating substrate comprises: a plurality of sheets of homogenised tobacco material stacked such that each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article, wherein, when the sheets are not transverse, the angle refers to the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross-section of the aerosol-generating article, wherein the sheets are adapted to allow a flow of air in a longitudinal direction through the rod during use; and a wrapper circumscribing the plurality of sheets.

According to second aspect of the present invention, there is provided a method of at least partially making a rod for use as an aerosol-generating substrate in an aerosol-generating article, the method comprising the steps of: providing a continuous web of homogenous tobacco material; removing a plurality of sheets from the web; stacking the plurality of sheets such that each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article, wherein, when the sheets are not transverse, the angle refers to the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross- section of the aerosol-generating article; circumscribing the stacked sheets with a wrapper to form a continuous rod such that in the formed continuous rod each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article; and severing the continuous rod into a plurality of discrete rods.

According to a third aspect of the present invention, there is provided a rod for use as an aerosol-generating substrate in an aerosol-generating article, the rod comprising: a plurality of sheets of homogenised tobacco material stacked such each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article, wherein, when the sheets are not transverse, the angle refers to the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross-section of the aerosol- generating article, wherein the sheets are adapted to allow a flow of air in a longitudinal direction through the rod during use; and a wrapper circumscribing the plurality of sheets. Any references below to preferred features or aspects of the rod of aerosol-generating substrate of aerosol- generating articles according to the invention should be considered to be applicable to all three aspects of the present invention.

As used herein, the term "heated aerosol-generating article" refers to an aerosol- generating article for producing an inhalable aerosol comprising an aerosol-generating substrate that is intended to be heated rather than combusted in order to release volatile compounds that can form an aerosol.

As used herein, the term "aerosol-generating substrate" refers to a substrate capable of releasing upon heating volatile compounds, which can form an aerosol. The aerosol generated from aerosol-generating substrates of aerosol-generating articles described herein may be visible or invisible and may include vapours (for example, fine particles of substances, which are in a gaseous state, that are ordinarily liquid or solid at room temperature) as well as gases and liquid droplets of condensed vapours.

As used herein, the term "rod" refers to a generally cylindrical element of substantially polygonal cross-section and preferably of circular, oval or elliptical cross-section. The term "sheet" is used herein to refer to a laminar element having a width and length substantially greater than the thickness thereof. The term "web" is used herein to refer to a laminar material having a length that is substantially greater than the width thereof. Typically, the term "web" is used herein to refer to the continuous layer of material from which the sheets are formed.

As used herein, the term "homogenised tobacco material" encompasses any tobacco material formed by the agglomeration of particles of tobacco material. Sheets or webs of homogenised tobacco material are formed by agglomerating particulate tobacco obtained by grinding or otherwise powdering of one or both of tobacco leaf lamina and tobacco leaf stems. In addition, homogenised tobacco material may comprise a minor quantity of one or more of tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the treating, handling and shipping of tobacco. The sheets of homogenised tobacco material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

As used herein, the term "longitudinal" refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream and downstream ends of the aerosol-generating article. During use, air is drawn through the aerosol- generating article in the longitudinal direction. The term "transverse" refers to the direction that is perpendicular to the longitudinal axis.

Any reference to the "cross-section" of the aerosol-generating article or a component of the aerosol-generating article refers to the transverse cross-section unless stated otherwise. As used herein, the term "length" refers to the dimension of a component in the longitudinal direction and the term "width" refers to the dimension of a component in the transverse direction. The term "maximum width" refers to the maximum cross-sectional dimension of a component. For example, in the case of a rod having a circular cross-section, the maximum width corresponds to the diameter of the circle. When used in relation to the sheets of homogenised tobacco material, the term "width" refers to the width of the sheet when it is laid flat, irrespective of the spatial orientation of the sheet within the aerosol-generating article.

As used herein, the term "stacked" refers to the arrangement of the plurality of sheets one over another. In the present invention, the "stacked" sheets may have spacing between adjacent sheets or adjacent sheets may be at least partially in contact with each other. The term "stacked" is used herein irrespective of the orientation of the stacked sheets.

As used herein, the terms "upstream" and "downstream" describe the relative positions of elements, or portions of elements, of the aerosol-generating article in relation to the direction in which the aerosol is transported through the aerosol-generating article during use.

As described above, the aerosol-generating article of the present invention incorporates a rod formed of a plurality of tobacco-containing sheets that each extend at an angle of at least 45 degrees to the longitudinal axis and are stacked longitudinally along the length of the rod. The regular arrangement of the plurality of sheets advantageously provides the rod with a highly consistent tobacco distribution and resistance to draw. The resistance to draw of the rod can be readily controlled through the adjustment of the level of air flow through the sheets. The regular arrangement of the plurality of sheets can also optimise heat transfer from a heater element that is in contact with the rod during use through the rod. Furthermore, any spacing provided between adjacent sheets may improve the heat transfer in a transverse direction as a result of the effective transfer of heat that can occur in the spaces between the sheets. For example, the heat transfer from an external heater to the centre of the sheets or the heat transfer from an internal heater to the periphery of the sheets may be improved. Advantageously, the sheets may be readily adapted to facilitate insertion of a heater element, such as a heater blade, into the rod.

The use of aerosol-generating substrates comprising sheets of homogenised tobacco material advantageously significantly reduce the risk of "loose ends" compared to an aerosol- generating substrate comprising shreds of tobacco material. The problems associated with loose ends, as described above, are therefore minimised.

Aerosol-generating substrates comprising sheets of homogenised tobacco material also advantageously exhibit significantly lower weight standard deviations than aerosol-generating substrate comprising shreds of tobacco material. The weight of an aerosol-generating substrate comprising stacked sheets of homogenised tobacco material is determined by the number, density, spacing, width and thickness of the sheets. The weight of aerosol-generating substrates comprising a plurality of sheets of homogenised tobacco material can thus be regulated by controlling the density and dimensions of the sheets of homogenised tobacco material and the arrangement of sheets within the rod. This reduces inconsistencies in weight between aerosol- generating substrates of the same dimensions, and so results in lower rejection rate of aerosol- generating substrates whose weight falls outside of a selected acceptance range compared to aerosol-generating substrate comprising shreds of tobacco material.

Aerosol-generating substrates comprising a plurality of sheets of homogenised tobacco material also advantageously exhibit more uniform densities than aerosol-generating substrates comprising shreds of tobacco material.

Insertion of a heater element of an aerosol-generating device into an aerosol-generating substrate comprising shreds of tobacco material and withdrawal of a heater element of an aerosol- generating device into an aerosol-generating substrate comprising shreds of tobacco material may tend to dislodge shreds of tobacco material from the aerosol-generating substrate. This can disadvantageously result in the need for more frequent cleaning of the heater element and other parts of the aerosol-generating device in order to remove the dislodged shreds. In contrast, insertion and withdrawal of a heater element of an aerosol-generating device into an aerosol- generating substrate comprising a plurality of sheets of homogenised tobacco material advantageously does not tend to dislodge tobacco material.

The rod of the aerosol-generating articles of the present invention can be made in a continuous process which can be efficiently carried out at high speed and can be conveniently incorporated into existing production lines for the manufacture of heated smoking articles.

Aerosol-generating articles according to the present invention are suitable for use in an aerosol-generating system comprising an electrically heated aerosol-generating device having an internal heater element for heating the aerosol-generating substrate. For example, aerosol- generating articles according to the invention find particular application in aerosol-generating systems comprising an electrically heated aerosol-generating device having an internal heater blade which is adapted to be inserted into the rod of aerosol-generating substrate. Aerosol- generating articles of this type are described in the prior art, for example, in European patent application EP-A-0 822 670.

As used herein, the term 'aerosol-generating device" refers to a device comprising a heater element that interacts with the aerosol-generating substrate of the aerosol-generating article to generate an aerosol.

Alternatively, aerosol-generating article according to the invention may comprise a combustible carbon heat source for heating the aerosol-generating substrate during use. Aerosol-generating articles of this type are described in the prior art, for example, in International patent application WO-A-2009/022232.

In the arrangement of sheets forming the rod of aerosol-generating articles according to the invention, each sheet is arranged such that the plane of the sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article. Preferably, the plane of each sheet extends at an angle of at least 60 degrees to the longitudinal axis of the aerosol- generating article, and most preferably, each sheet extends substantially transversely across the aerosol-generating article, substantially perpendicular to the longitudinal axis. The stack of sheets therefore extends along the length of the rod. Where the sheets are not transverse, the "angle" referred to is the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross-section of the aerosol-generating article.

Where a sheet is not flat, for example, where a sheet is crimped or curved, the required angle of the sheet should be assumed to be provided if the overall extension of the sheet in the longitudinal direction of the aerosol-generating article is less than or equal to the overall extension of the sheet in the transverse direction.

According to the invention, the sheets are adapted to allow a flow of air in a longitudinal direction through the rod during use. This means that each sheet must be adapted in some way to provide one or more air flow pathways through the sheet. The degree to which air is able to flow through the sheet may be varied depending on the desired resistance to draw of the aerosol- generating article incorporating the rod of aerosol-generating substrate comprising the transverse sheets.

There are a number of alternative ways of adapting the sheets of homogenised tobacco material in order to provide the desired flow of air through the sheets. In certain preferred embodiments of the invention, each of the plurality of sheets comprises one or more cut outs in the interior of the sheet. Each of the one or more cut outs provides an opening in the sheet through which air is able to pass during use of the aerosol-generating article.

Preferably, the one or more cut outs are arranged substantially centrally within the sheet. Particularly preferably, each sheet comprises a single, central cut out.

Preferably, the cut outs in the plurality of sheets are substantially aligned to form a longitudinal channel extending through the rod of aerosol-generating substrate. The longitudinal channel provides an effective air flow channel to allow air to flow through the rod during use. In addition, the longitudinal channel may advantageously facilitate the insertion of a heater element into the rod of aerosol-generating substrate during use of the aerosol-generating article with an aerosol-generating device. For example, the shape, size and position of the cut outs may be adapted such that a heater blade can be received into the longitudinal channel created by the cut outs of the plurality of sheets.

Preferably, each sheet comprises a cut out comprising an arrangement of one or more slits, wherein the slits are adapted to receive a heater blade of an aerosol-generating device. Particularly preferably, each sheet comprises a cut out comprising a cross shape or star shape formed by a plurality of slits having a different orientation to each other. This arrangement may facilitate the insertion of a relatively flat heater blade into the rod of aerosol-generating substrate, since it is possible to insert the heater blade with several different rotational orientations of the aerosol-generating article. It should therefore not be necessary for the user to accurately align the heater blade with the cut out before insertion of the heater blade into the rod.

The size and shape of the cut out in each sheet may also be adapted to provide the required resistance to draw (RTD) of the aerosol-generating article. In general, the largerthe size of the cut out, the easier the air will be able to flow through the sheets and therefore the lower the resistance to draw.

In alternative embodiments of the invention, the one or more cut outs in the plurality of sheets may not be aligned with each other but may be provided at two or more different positions so that a continuous longitudinal channel is not provided. Instead, a more tortuous air flow pathway may be provided through the rod, which may be used, for example, to increase the RTD of the aerosol-generating article.

Alternatively or in addition to the provision of one or more cut outs in each sheet, the sheets may be formed of a porous tobacco material. The term "porous" is used herein to refer to a material that provides a plurality of pores or openings that allow the passage of air through the material. The tobacco material may be produced within an inherent porosity so that sufficient pores or interstices are provided within the structure of each sheet to enable the flow of air through the sheet in a longitudinal direction. Alternatively or in addition, each sheet of tobacco material may comprise a plurality of air flow holes to provide the desired porosity. For example, the sheet of tobacco material may be punctured with a pattern of air flow holes during production of the rod of aerosol-generating substrate. The air flow holes may be punctured randomly or uniformly over the sheet. The pattern of air flow holes may cover substantially the full surface of the sheet, or may cover one or more specific areas of the sheet, with the remaining areas being free from air flow holes.

Alternatively or in addition to the provision of any of the means discussed above for providing the desired level of air flow through the rod of aerosol-generating substrate, the size or shape of the sheets of tobacco material may be adapted such that there are one or more gaps present between the outer edge of each sheet and the inner surface of the wrapper. Such an arrangement enables the flow of air around the outside of the stack of sheets.

Preferably, the resistance to draw (RTD) of the aerosol-generating article after insertion of a heater element is between about 80 mm WG and about 140 mm WG, more preferably between about 100 mm WG and about 120 mm WG.

As used herein, resistance to draw is expressed with the units of pressure 'mm WG' or 'mm of water gauge' and is measured in accordance with ISO 6565:2002.

The resistance to draw (RTD) of the rod of aerosol-generating substrate is preferably between about 50 mm WG and about 80 mm WG. Preferably, the RTD of the rod of aerosol- generating substrate is between about 5 mm WG and about 8 mm WG per millimetre length of the rod.

The RTD of the rod may be adapted by varying the air flow pathways through the sheets, as described above. Alternatively or in addition, the RTD of the rod may be adapted by varying other aspects of the sheets or the arrangement of sheets, including but not limited to the thickness of the sheets and the spacing of the sheets.

In preferred embodiments of the invention, each of the plurality of sheets is substantially flat or planar and arranged substantially perpendicular to the longitudinal axis of the aerosol- generating article. Preferably, the plurality of sheets are arranged substantially parallel to each other. In alternative embodiments, one or more of the sheets may be non-planar. For example, one or more of the sheets may be curved towards or away from the mouth end of the aerosol- generating article.

Preferably, the shape of each sheet substantially corresponds to the cross-sectional shape of the rod of aerosol-generating substrate. This provides the rod with a stable structure since the sheets can be effectively braced against the wrapper and optionally adhered to the inner surface of the wrapper, in order to retain the sheets in position within the rod. As discussed above, small gaps may be provided between the sheets and the wrapper as described above whilst retaining an overall similarity between the shape of the sheets and the cross-sectional shape of the rod.

In some preferred embodiments of the present invention, the plurality of sheets within the rod are spaced apart from each other in the longitudinal direction. The spacing between adjacent sheets may be substantially constant throughout the rod. Alternatively, the spacing between adjacent sheets may differ between different sheets in the rod.

Preferably, in such embodiments, the sheets are spaced apart from each other in a longitudinal direction by at least about 50 microns, more preferably at least about 100 microns and most preferably at least about 150 microns. Alternatively or in addition, the sheets are preferably spaced apart from each other in a longitudinal direction by no more than about 1500 microns, more preferably no more than about 800 microns and most preferably no more than about 600 microns. For example, the sheets may be spaced apart from each other in a longitudinal direction by between about 50 microns and about 1500 microns, more preferably by between about 100 microns and about 800 microns and most preferably by between about 150 microns and about 600 microns.

The longitudinal spacing between the sheets may be retained in the aerosol-generating article due to friction between the outer edges of the sheets and the inner surface of the wrapper. Alternatively or in addition, the outer edges of the sheets may be adhered to the inner surface of the wrapper, as discussed in more detail below. Optionally, one or more layers of a non-tobacco material may be provided between adjacent spaced apart sheets of tobacco material in the rod of aerosol-generating substrate. In certain embodiments, the one or more layers of non-tobacco material may help to retain the desired spacing between adjacent sheets of tobacco material within the stack. Suitable non- tobacco layers would be known to the skilled person but may include, for example, nicotine- containing layers or flavourant containing layers. The layers of non-tobacco material may take a variety of different forms including but not limited to a sheet, a film, a coating and a particulate material such as a powder. Preferably, the non-tobacco layers are porous such that they do not impede the air flow through the stacked sheets of tobacco material. The non-tobacco layers may or may not extend over the full cross-section of the rod of aerosol-generating substrate.

In other preferred embodiments of the present invention, the plurality of sheets are stacked such that adjacent sheets are in contact with each other, with substantially no longitudinal spacing between them.

The number of sheets within the rod can be varied depending on the thickness of the sheets and the length of the rod. Typically, the rod comprises between 2 and 100 sheets.

Preferably, the thickness of each sheet is at least about 40 microns more preferably at least about 60 microns, more preferably at least about 80 microns and most preferably at least about 100 microns. Alternatively or in addition, the thickness of each sheet is preferably no more than about 5000 microns, more preferably no more than about 2000 microns, more preferably no more than about 1000 microns and most preferably no more than about 500 microns. For example, the thickness of each sheet may be between about 40 microns and about 5000 microns, more preferably between about 60 microns and about 2000 microns, more preferably between about 80 microns and about 1000 microns and most preferably by between about 100 microns and about 500 microns.

The plurality of sheets may all have substantially the same thickness as each other.

Alternatively, the plurality of sheets may include sheets of at least two different thicknesses.

Preferably, the sheets have a weight of at least about 40 grams per square meter, more preferably at least about 60 grams per square meter, more preferably at least about 80 grams per square meter and most preferably at least about 100 grams per square meter. Alternatively or in addition, the sheets preferably have a weight of no more than about 5000 grams per square meter, more preferably no more than about 2000 grams per square meter, more preferably no more than about 1000 grams per square meter and most preferably no more than about 500 grams per square meter. For example, the weight of the sheets may be between about 40 grams per square meter and about 5000 grams per square meter, more preferably between about 60 grams per square meter and about 2000 grams per square meter, more preferably between about 80 grams per square meter and about 1000 grams per square meter and most preferably between about 100 grams per square meter and about 500 grams per square meter. The plurality of sheets may all have substantially the same weight as each other. Alternatively, the plurality of sheets may include sheets of at least two different weights.

Each sheet may comprise a single layer of homogenous tobacco material. Alternatively, one or more of the sheets may be a multilayer sheet formed of a plurality of overlying layers of homogenous tobacco material. For example, a web of homogenous tobacco material may be folded back on itself one or more times to form a multilayer sheet.

In certain embodiments of the present invention, at least one of the plurality of sheets forming the rod may be textured over at least a part of its surface. As used herein the term "textured" refers to a sheet that has been crimped, embossed, debossed, perforated or otherwise locally deformed. For example, at least one of the sheets may comprise a plurality of spaced- apart indentations, protrusions, perforations or a combination thereof. Texture may be provided on one side of each sheet, or on both sides each sheet.

In a particularly preferred embodiment, at least one of the sheets is crimped. As used herein, the term "crimped" denotes a sheet having a plurality of substantially parallel ridges or corrugations. The inclusion of one or more crimped sheets may help to retain the spacing between adjacent sheets within the rod.

Alternatively or in addition to the provision of texture on the surface of at least one of the plurality of sheets, an additive may be applied to at least a part of a surface of at least one of the plurality of sheets. The additive may be a solid additive, a liquid additive, or a combination of a solid additive and a liquid additive. Suitable solid and liquid additives for use in the invention are known in the art and include, but are not limited to: flavourants, such as for example menthol; adsorbents, such as for example activated carbon; fillers, such as for example calcium carbonate; and botanical additives.

The plurality of sheets of the rod of aerosol-generating articles according to the invention are formed of a homogenous tobacco material, which preferably comprises particulate tobacco obtained by grinding or otherwise comminuting tobacco leaf lamina. The plurality of sheets may all have substantially the same composition as each other. Alternatively, the plurality of sheets may include sheets of at least two different compositions.

Sheets of homogenised tobacco material for use in the invention may have a tobacco content of at least about 40 percent by weight on a dry weight basis, more preferably of at least about 60 percent by weight on a dry weight basis, more preferably or at least about 70 percent by weight on a dry basis and most preferably at least about 90 percent by weight on a dry weight basis.

Sheets of homogenised tobacco material for use in the aerosol-generating substrate may comprise one or more intrinsic binders, that is tobacco endogenous binders, one or more extrinsic binders, that is tobacco exogenous binders, or a combination thereof to help agglomerate the particulate tobacco. Alternatively, or in addition, sheets of homogenised tobacco material for use in the aerosol-generating substrate may comprise other additives including, but not limited to, tobacco and non-tobacco fibres, aerosol-formers, humectants, plasticisers, flavourants, fillers, aqueous and non-aqueous solvents and combinations thereof.

Suitable extrinsic binders for inclusion in sheets of homogenised tobacco material for use in the aerosol-generating substrate are known in the art and include, but are not limited to: gums such as, for example, guar gum, xanthan gum, arabic gum and locust bean gum; cellulosic binders such as, for example, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose and ethyl cellulose; polysaccharides such as, for example, starches, organic acids, such as alginic acid, conjugate base salts of organic acids, such as sodium- alginate, agar and pectins; and combinations thereof.

Suitable non-tobacco fibres for inclusion in sheets of homogenised tobacco material for use in the aerosol-generating substrate are known in the art and include, but are not limited to: cellulose fibers; soft-wood fibres; hard-wood fibres; jute fibres and combinations thereof. Prior to inclusion in sheets of homogenised tobacco material for use in the aerosol-generating substrate, non-tobacco fibres may be treated by suitable processes known in the art including, but not limited to: mechanical pulping; refining; chemical pulping; bleaching; sulfate pulping; and combinations thereof.

Preferably, the sheets of homogenised tobacco material comprise an aerosol former. As used herein, the term "aerosol former" describes any suitable known compound or mixture of compounds that, in use, facilitates formation of an aerosol and that is substantially resistant to thermal degradation at the operating temperature of the aerosol-generating article.

Suitable aerosol-formers are known in the art and include, but are not limited to: polyhydric alcohols, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and, most preferred, glycerine.

The sheets of homogenised tobacco material may comprise a single aerosol former. Alternatively, the sheets of homogenised tobacco material may comprise a combination of two or more aerosol formers.

Preferably, the sheets of homogenised tobacco material have an aerosol former content of greater than 5 percent on a dry weight basis. The sheets of homogenised tobacco material may have an aerosol former content of between approximately 5 percent and approximately 30 percent on a dry weight basis. In a preferred embodiment, the sheets of homogenised tobacco material have an aerosol former content of approximately 20 percent on a dry weight basis.

Sheets of homogenised tobacco for use in the aerosol-generating article of the present invention may be made by methods known in the art, for example the methods disclosed in International patent application WO-A-2012/164009 A2.

In a preferred embodiment, sheets of homogenised tobacco material for use in the aerosol-generating article are formed from a slurry comprising particulate tobacco, guar gum, cellulose fibres and glycerine by a casting process.

The rod of aerosol-generating substrate preferably 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. The rod of aerosol-generating substrate may have an external diameter of between about 5 millimetres and about 12 millimetres, for example of between about 5 millimetres and about 10 millimetres or of between about 6 millimetres and about 8 millimetres. In a preferred embodiment, the rod of aerosol-generating substrate has an external diameter of 7.2 millimetres, to within 10 percent.

The rod of aerosol-generating substrate may have a length of between about 7 millimetres and about 15 mm. In one embodiment, the rod of aerosol-generating substrate may have a length of about 10 millimetres. In a preferred embodiment, the rod of aerosol-generating substrate has a length of about 12 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.

As described above, the plurality of sheets forming the rod of aerosol-generating substrate are circumscribed by a wrapper. The wrapper may be formed of a porous or non-porous sheet material. The wrapper may be formed of any suitable material or combination of materials. Preferably, the wrapper is a paper wrapper. The wrapper may optionally be adhered to the outer edges of the plurality of sheets. For example, at least one of the inner surface of the wrapper and the outer edges of the plurality of sheets may be wetted during the production process such that the inner wrapper adheres to the edges of the sheets during the wrapping process. Alternatively, an adhesive may be applied to at least one of the inner surface of the wrapper and the outer edges of the plurality of sheets upstream of the wrapping step. The adhesion of the plurality of sheets and the wrapper may advantageously help to retain the position and spacing of the plurality of sheets within the rod.

The wrapper may optionally be at least partially folded over the sheets at the upstream and downstream ends of the rod to retain the plurality of sheets within the rod. Preferably, the wrapper overlies the periphery of the upstream and downstream sheets so that the remainder of the sheets is exposed. However, in some embodiments the wrapper may overlie the entire upstream and downstream sheets. In such embodiments, the air flow may advantageously be provided the wrapper having a sufficient porosity to enable air flow through the ends of the rod. Alternatively or in addition, the wrapper may be arranged such that it does not cover any cut outs in the tobacco sheets.

As an alternative to folding the ends of the wrapper over the upstream and downstream sheets of tobacco material, a separate rim section of paper or other material may be attached to the wrapper to overlie at least the periphery of the upstream and downstream sheets, as described above.

In such embodiments where the wrapper is folded over the ends of the rod, or where a separate rim section is provided, an additional outer wrapper may be provided overlying the wrapper that circumscribes the plurality of sheets.

The aerosol-generating articles according to the invention preferably comprise one or more elements in addition to the rod of aerosol-generating substrate, wherein the rod and the one or more elements are assembled within a substrate wrapper. For example, aerosol-generating articles according to the invention may further comprise at least one of: a mouthpiece, an aerosol- cooling element and a support element such as a hollow acetate tube. For example, in one preferred embodiment, an aerosol-generating article comprises, in linear sequential arrangement, a rod of aerosol-generating substrate as described above, a support element located immediately downstream of the aerosol-generating substrate, an aerosol-cooling element located downstream of the support element, and an outer wrapper circumscribing the rod, the support element and the aerosol-cooling element.

The rods for use in aerosol-generating article according to the invention, described in detail above, may be produced using a method according to the second aspect of the invention, as defined above. In a first step of the method according to the invention, a continuous web of homogeneous tobacco material is provided. In a second step, a plurality of sheets are removed from the web. In a third step, the plurality of sheets are stacked such that each sheet extends in the transverse direction. In a fourth step, the stacked sheets are circumscribed by a wrapper to form a continuous rod and in a fifth step, the continuous rod is severed into a plurality of discrete rods.

In relation to the method of the present invention, the term "longitudinal" refers to the longitudinal axis of the continuous rod, which typically also corresponds to the direction of travel of the continuous sheets and the continuous rod through the apparatus. As defined above, the term "transverse" refers to the direction perpendicular to the longitudinal direction.

Preferably, the step of removing a plurality of sheets from the continuous web of tobacco material comprises cutting the sheets from the web. Particularly preferably, the plurality of sheets are cut from the web with a hollow cylindrical cutter wherein each sheet enters the inside of the hollow cylindrical cutter upon cutting, such that the plurality of sheets are continuously stacked inside the hollow cylindrical cutter. This provides an efficient way in which to stack the sheets of tobacco material as they are cut from the web. The hollow cylindrical cutter provides both a cutting means for stamping the sheets from the web and a transport tube for stacking the sheets and transporting the stacked sheets towards the wrapping station. The cutting means is preferably narrower than the transport tube so that the inner surfaces of the transport tube do not hinder the flow of the stack of sheets through the tube.

In alternative embodiments, one or more cutters may be provided separately from one or more transport tubes, wherein means are provided for feeding the sheets into the transport tubes after they have been removed from the sheet.

A plurality of cutters may optionally be used on the same tobacco web in order to remove a plurality of sheets form the web at the same time. The stack of sheets from each cutter may be transported to separate lines for wrapping or cutting, or the stacks may be combined downstream of the cutting step to provide a single line. A similar process may be used for embodiments in which sheets of homogenised tobacco material having different compositions to each other are combined to form the rods.

In embodiments in which the sheets of homogenised tobacco material are combined with layers of non-tobacco material, the method may comprise an additional step of incorporating the non-tobacco material into the stack of sheets as they leave the transport tube or tubes, prior to the wrapping of the stacked sheets. Where a plurality of cutters is used, this step of incorporating the non-tobacco material may advantageously be carried out as the separate stacks of sheets are combined.

In any of the embodiments, the stack of sheets may be forced through the transport tube automatically as new sheets are cut and enter the end of the tube, thereby pushing the other sheets further away from the web. Alternatively or in addition, steps may be taken to force the stack of sheets through the transport tube. For example, an air flow may be directed into the transport tube or the transport tube may be vibrated in order to prevent any of the sheets from becoming stuck.

Optionally, methods according to the invention may further comprise the step of forming a cut out in the interior of each of the sheets. Spaced apart cut outs are preferably formed in the continuous web of tobacco material, upstream of the step of removing the sheets from the web. In this case, the cut outs need to be aligned in the desired position of the sheet during the step of removing the sheets from the web. The cut outs may be formed by one or more oscillating cutters of the desired shape or a plurality of cutters may be provided on the surface of a rotating drum that moves at substantially the same speed as the continuous web.

Optionally, methods according to the invention may further comprise the step of providing a plurality of holes in the continuous web of tobacco material upstream of the step of removing the sheets from the web, in order to provide the sheets with a plurality of air flow holes as described above. The holes may be punctured in the continuous web by an arrangement of pins which oscillate up and down as the continuous web is moved underneath. Alternatively, a pattern of holes may be punctured by an arrangement of pins on a rotating drum that moves at the same speed as the continuous web. Non-mechanical means for forming holes in the continuous web, such as lasers, may also be used.

Methods according to the invention may further comprise the step of texturing the continuous sheets of homogenised tobacco material, or the continuous web of homogenous tobacco material, prior to the stacking step. For example, sheets of homogenised tobacco material for use in the present invention may be crimped using a crimping unit of the type described in Swiss patent application CH-A-691156, which comprises a pair of rotatable crimping rollers. However, it will be appreciated that sheets of homogenised tobacco material for use in the invention may be textured using other suitable machinery and processes that deform or perforate the sheets.

Alternatively or in addition, methods according to the invention may further comprise the step of applying one or more additives to the continuous web of homogenous tobacco material, or the continuous web of homogenous material, prior to the step of removing the sheets from the web.

The steps of circumscribing the plurality of sheets with the wrapper to form a continuous rod and severing the continuous rod to form discrete rods may be carried out using existing apparatus and techniques, which would be known to the skilled person.

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

Figure 1 shows a schematic longitudinal cross-sectional view of an aerosol-generating article for use with an aerosol-generating device comprising a heater element;

Figure 2 shows a schematic perspective view of an aerosol-generating substrate according to a first embodiment of the invention, with the wrapper removed;

Figure 3 shows a schematic perspective view of the aerosol-generating substrate of Figure 2, with the wrapper in place;

Figure 4 shows a schematic perspective view of an aerosol-generating substrate according to a second embodiment of the invention, with the wrapper removed;

Figure 5 shows a schematic perspective view of the aerosol-generating substrate of Figure 4, with the wrapper in place; and

Figure 6 shows a schematic longitudinal cross-sectional view of an aerosol-generating system comprising an electrically operated aerosol-generating device and the aerosol-generating article shown in Figure 1.

The aerosol-generating article 10 shown in Figure 1 comprises a rod of aerosol-generating substrate 12, a hollow cellulose acetate tube 14, a spacer element 16 and a mouthpiece filter 18. These four elements are arranged sequentially and in coaxial alignment and are circumscribed by a substrate wrapper 20 to form the aerosol-generating article 10. The aerosol-generating article 10 has a mouth end 22 and a distal end 24 located at the opposite end of the article to the mouth end 22. The aerosol-generating article 10 shown in Figure 1 is particularly suitable for use with an electrically operated aerosol-generating device comprising a heater for heating the rod of aerosol-generating substrate.

The rod of aerosol-generating substrate 12 has a length of approximately 12 millimetres and a diameter of approximately 7 millimetres. The rod 12 is cylindrical in shape and has a substantially circular cross-section.

A first embodiment of a rod of aerosol-generating substrate 12 for use in the aerosol- generating article 10 of Figure 1 is shown in Figures 2 and 3. The rod 12 comprises a plurality of sheets of homogenised tobacco material 30 circumscribed by a paper wrapper 32. In Figure 2, the plurality of sheets 30 are shown with the wrapper 32 removed.

As can be seen in Figure 2, each of the plurality of sheets 30 is substantially planar and extends in a transverse direction. The sheets 30 are parallel to each other and stacked such that adjacent sheets are in contact with each other, with no longitudinal spacing between them. The sheets 30 are circular in shape and have a diameter substantially corresponding to the diameter of the rod 12. As shown in Figure 3, the edges of each sheet are proximate the inner surface of the wrapper 32.

Each of the sheets 30 has a thickness of approximately 250 microns. The rod contains approximately 45 sheets.

Each of the sheets 30 comprises a central cut out 34 which is formed by three slits that are centred about the same point and angularly spaced apart in a star configuration. The central cut outs 34 are aligned to form a longitudinal channel that extends through the rod 12. The longitudinal channel is adapted to receive a heater blade of an aerosol-generating device, as described below, and to provide an air flow pathway through which air can be drawn through the rod 12 during use.

A second embodiment of a rod of aerosol-generating substrate 112 for use in the aerosol- generating article 10 of Figure 1 is shown in Figures 4 and 5. As in the previously described embodiment, the rod 112 comprises a plurality of sheets of homogenised tobacco material 130 circumscribed by a paper wrapper 132. In Figure 4, the plurality of sheets 130 are shown with the wrapper 132 removed.

As can be seen in Figure 4, each of the plurality of sheets 130 is substantially planar and extends in a transverse direction. The sheets 130 are arranged substantially parallel to each other and are spaced apart from each other in the longitudinal direction. The longitudinal spacing between adjacent sheets is substantially constant throughout the rod 1 12. The sheets 30 are circular in shape and have a diameter substantially corresponding to the diameter of the rod 1 12. As shown in Figure 5, the edges of each sheet are proximate the inner surface of the wrapper 132. Each of the sheets 130 comprises a plurality of air flow holes (not shown) arranged over the entire surface, which provide the sheets 130 with sufficient porosity to enable air flow through the rod 112 during use.

Figure 6 shows a portion of an electrically operated aerosol-generating system 200 that utilises a heater blade 210 to heat the rod of aerosol-generating substrate 12 of the aerosol- generating article 10 shown in Figure 1. The heater blade 210 is mounted within an aerosol- generating article chamber within a housing of an electrically operated aerosol-generating device 212. The aerosol-generating device 212 defines a plurality of air holes 214 for allowing air to flow to the aerosol-generating article 10, as illustrated by the arrows in Figure 6. The aerosol- generating device 212 comprises a power supply and electronics, which are not shown in Figure 6.

The aerosol-generating article 10 shown in Figure 1 is designed to engage with the aerosol-generating device 212 shown in Figure 6 in order to be consumed. The user inserts the aerosol-generating article 10 into the aerosol-generating device 212 so that the heater blade 210 is inserted into the rod of aerosol-generating substrate 12, through the layers of homogenised tobacco material 30. The mouthpiece filter 18 projects outwards from the mouth end of the device 212. Once the aerosol-generating article 10 is engaged with the aerosol-generating device 212, the user draws on the mouth end 22 of the aerosol-generating article 10 and the rod of aerosol- generating substrate 12 is heated by the heater blade 210 to a temperature sufficient to generate an aerosol from the rod of aerosol-generating substrate 12. The aerosol is drawn through the mouth end filter 18 and into the user's mouth.

It will be appreciated that the aerosol-generating article 10 shown in Figure 1 may also be suitable for use with other types of aerosol-generating devices.

Claims

1. A heated aerosol-generating article comprising a rod of aerosol-generating substrate, wherein the rod of aerosol-generating substrate comprises:

a plurality of sheets of homogenised tobacco material stacked such that each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol- generating article, wherein, when the sheets are not transverse, the angle refers to the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross-section of the aerosol-generating article,

wherein the sheets are adapted to allow a flow of air in a longitudinal direction through the rod during use; and

a wrapper circumscribing the plurality of sheets.

2. A heated aerosol-generating article according to claim 1 wherein the plurality of sheets of homogenised tobacco material are stacked such that each sheet extends in the transverse direction of the aerosol-generating article.

3. A heated aerosol-generating article according to claim 1 or 2 wherein each of the plurality of sheets comprises one or more cut outs in the interior of the sheet.

4. A heated aerosol-generating article according to any of claims 1 to 3 wherein the plurality of sheets are formed of a porous tobacco material.

5. A heated aerosol-generating article according to claim 4 wherein each of the plurality of sheets comprises a plurality of air flow holes.

6. A heated aerosol-generating article according to any preceding claim wherein the resistance to draw (RTD) of the rod of aerosol-generating substrate is between about 5 mm WG and about 8 mm WG per millimetre of the rod.

7. A heated aerosol-generating article according to any preceding claim wherein the plurality of sheets are spaced apart from each other in the longitudinal direction of the rod.

8. A heated aerosol-generating article according to claim 7 further comprising one or more layers of a non-tobacco material between adjacent sheets of tobacco material in the rod.

9. A heated aerosol-generating article according to any preceding claim wherein the thickness of each of the plurality of sheets is between 40 microns and 5000 microns.

10. A heated aerosol-generating article according to any preceding claim wherein one or more of the plurality of sheets are textured, preferably crimped.

1 1. A heated aerosol-generating article according to any preceding claim wherein the wrapper circumscribing the plurality of sheets is at least partially folded over the sheets at the upstream and downstream ends of the rod to retain the plurality of sheets within the rod.

12. A method of making a rod for use as an aerosol-generating substrate in an aerosol- generating article, the method comprising the steps of:

providing a continuous web of homogenous tobacco material;

removing a plurality of sheets from the web;

stacking the plurality of sheets such that each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article, wherein, when the sheets are not transverse, the angle refers to the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross-section of the aerosol- generating article;

circumscribing the stacked sheets with a wrapper to form a continuous rod, such that in the formed continuous rod each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol-generating article; and

severing the continuous rod into a plurality of discrete rods.

13. A method according to claim 12 wherein the step of removing a plurality of sheets from the web comprises cutting the sheets from the web with a hollow cylindrical cutter and wherein each sheet enters the inside of the hollow cylindrical cutter upon cutting, such that the plurality of sheets are continuously stacked inside the hollow cylindrical cutter.

14. A method according to claim 12 or 13 further comprising the step of forming a cut out in the interior of each of the sheets.

15. A rod for use as an aerosol-generating substrate in an aerosol-generating article, the rod comprising:

a plurality of sheets of homogenised tobacco material stacked such that each sheet extends at an angle of at least 45 degrees to the longitudinal axis of the aerosol- generating article, wherein the sheets are adapted to allow a flow of air in a longitudinal direction through the rod during use, wherein, when the sheets are not transverse, the angle refers to the acute angle between the line defined by the plane of the sheet and the longitudinal axis, measured in the longitudinal cross-section of the aerosol-generating article; and

a wrapper circumscribing the plurality of sheets.