Porous aerosol-generating element comprising cut filler

Abstract

A porous aerosol-generating element (40)(114) for generating an inhalable aerosol upon heating, the porous aerosol-generating element (40)(114) comprises: a solid binder matrix comprising at least one binder, wherein the porous aerosol-generating element (40)(114) comprises at least 1 percent by weight of the binder on a dry weight basis; and cut filler dispersed within the solid binder matrix, the cut filler comprising shredded plant material impregnated with an aerosol former, wherein the shredded plant material has an average cut width of at least 0.75 millimetres, wherein the porous aerosol-generating element (40)(114) comprises at least 10 percent by weight of the aerosol former on a dry weight basis. The porous aerosol-generating element (40)(114) has an average density of less than or equal to 420 mg per cubic centimetre.

Description

[0001] POROUS AEROSOL-GENERATING ELEMENT COMPRISING CUT FILLER

[0002] The present invention relates to an aerosol-generating element for generating an inhalable aerosol upon heating, to an article including an aerosol-generating element and to a method of producing an aerosol-generating element.

[0003] A number of aerosol-generating articles in which an aerosol-generating substrate, such as tobacco, is heated rather than combusted have been proposed in the art. In these aerosolgenerating articles, an aerosol is typically generated by heating the aerosol-generating substrate to a predetermined temperature. For example, smoking articles have been disclosed in which an aerosol is generated by electrical heating or by the transfer of heat from a combustible fuel element or heat source to a tobacco-containing 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.

[0004] Typically, aerosol-generating articles in which tobacco is heated rather than combusted further comprise one or more elements paired with the aerosol-generating substrate. For example, aerosol-generating articles have been proposed which include a rod of aerosolgenerating substrate and one or more of a support element adapted to impart increased structural strength to the aerosol-generating article, an aerosol-cooling element configured to lower the temperature of the aerosol prior to the aerosol reaching a mouth end of the aerosol-generating article, and a mouthpiece element.

[0005] It is common to produce aerosol-generating articles in which the aerosol-generating substrate is formed from a cylindrical rod of tobacco material, such as cut filler. However, such cylindrical rods of tobacco material have not been found to provide optimal aerosol generation when heated, rather than combusted. A rod of cut filler will typically have a relatively high density and a relatively low porosity, due to the way in which the tobacco material is compacted during manufacture. This can present challenges for the uniform heating of the tobacco material and in fact, research has shown that a significant proportion of the cylindrical rod may not be sufficiently heated to form an aerosol during use. This proportion of the rod is therefore effectively wasted. Furthermore, the fixed size and shape of the cylindrical rod of cut filler provides little flexibility for the aerosol-generating substrate to be adapted for use in new, more efficient designs of aerosolgenerating article and aerosol-generating device.

[0006] It would be desirable to provide a novel substrate for a heated aerosol-generating article, which can achieve a more efficient generation of aerosol and which provides an improved experience for the consumer. It would be particularly desirable to provide such a novel substrate which offers more flexibility to be used in different shapes and forms, such that it can be adapted for use with a wider variety of aerosol-generating articles and devices. It would be further desirable to provide such a novel substrate which can be produced using existing methods and apparatus, with minimal modifications.

[0007] According to the present disclosure there is provided a porous aerosol-generating element for generating an inhalable aerosol upon heating. The porous aerosol-generating element may comprise a solid binder matrix. The solid binder matrix may comprise at least one binder. The porous aerosol-generating element may comprise at least 1 percent by weight of the binder on a dry weight basis. The aerosol-generating element may further comprise cut filler dispersed within the solid binder matrix. The cut filler may comprise shredded plant material impregnated with an aerosol former. The shredded plant material may have an average cut width of at least 0.75 millimetres. The porous aerosol-generating element may comprise at least 10 percent by weight of the aerosol former on a dry weight basis. The porous aerosol-generating element may have an average density of less than or equal to 420 mg per cubic centimetre.

[0008] According to the present invention there is provided a porous aerosol-generating element for generating an inhalable aerosol upon heating, the porous aerosol-generating element comprising: a solid binder matrix comprising at least one binder, wherein the porous aerosolgenerating element comprises at least 1 percent by weight of the binder on a dry weight basis; and cut filler dispersed within the solid binder matrix, the cut filler comprising shredded plant material impregnated with an aerosol former, wherein the shredded plant material has an average cut width of at least 0.75 millimetres, wherein the porous aerosol-generating element comprises at least 10 percent by weight of the aerosol former on a dry weight basis. According to the invention, the porous aerosol-generating element has an average density of less than or equal to 420 mg per cubic centimetre.

[0009] According to the present invention there is also provided an aerosol-generating article comprising an aerosol-generating element according to the invention, as defined above.

[0010] According to the present disclosure there is further provided a method of producing a porous aerosol-generating element according to the present disclosure, as defined above. The method may comprise the step of: providing a plant material. The method may comprise the step of: conditioning the plant material. The conditioning may include applying an aerosol former to the plant material. The amount of aerosol former applied to the plant material may corresponds to at least 15 percent by weight on a dry weight basis, based on the weight of the plant material. The method may comprise the step of: cutting the plant material to provide a shredded plant material with an average cut width of at least 0.75mm. The method may comprise the step of: drying the conditioned plant material to provide a cut filler having a defined moisture level. The method may comprise the step of: adding a binder solution comprising one or more binders to the cut filler and mixing the binder solution and the cut filler to at least partially coat the cut filler with the binder solution. The method may comprise the step of: compacting the mixture of binder solution and cut filler. The method may comprise the step of: drying the compacted mixture to form a solid substrate comprising a solid binder matrix having the cut filler dispersed through it. The method may comprise the step of: forming a discrete porous aerosol-generating element from the solid substrate.

[0011] According to the present invention there is provided a method of producing a porous aerosol-generating element according to the present invention, as defined above. The method according to the invention comprises the steps of: providing a plant material; conditioning the plant material, wherein the conditioning includes applying an aerosol former to the plant material, wherein the amount of aerosol former applied to the plant material corresponds to at least 15 percent by weight on a dry weight basis, based on the weight of the plant material; cutting the plant material to a provide a shredded plant material with an average cut width of at least 0.75mm; drying the conditioned plant material to provide a cut filler having a defined moisture level; adding a binder solution comprising one or more binders to the cut filler and mixing the binder solution and the cut filler to at least partially coat the cut filler with the binder solution; compacting the mixture of binder solution and cut filler; drying the compacted mixture to form a solid substrate comprising a solid binder matrix having the cut filler dispersed through it; and forming a discrete porous aerosol-generating element from the solid substrate.

[0012] As used herein, the term “aerosol-generating article” refers to an aerosol-generating article for producing an 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.

[0013] As used herein, the term “aerosol-generating element” refers to a discrete aerosolgenerating substrate in solid form, comprising cut filler dispersed within a solid binder matrix. The structure and composition of the aerosol-generating element will be described in more detail below.

[0014] An aerosol-generating element in accordance with the present invention may find use as an aerosol-generating substrate of an aerosol-generating article.

[0015] As used herein, the term “aerosol-generating substrate” refers to a substrate capable of releasing upon heating volatile compounds, which can form an aerosol.

[0016] The porous aerosol-generating element of the present invention provides a novel and improved form of aerosol-generating substrate for an aerosol-generating article. The aerosolgenerating element provides a porous structure, formed from a solid binder matrix through which is dispersed a cut filler comprising shredded plant material and aerosol former. The solid binder matrix carries and retains the cut filler and enables a material to be formed which has a relatively high porosity and a relatively low density. This, in turn, enables the aerosol-generating element to be heated very efficiently during use, so that the generation of aerosol from the aerosolgenerating element can be optimised and the amount of wasted plant material can be minimised.

[0017] The form of the aerosol-generating element enables it to be used in a variety of shapes and forms, such that the aerosol-generating element offers improved flexibility and versatility for use in a variety of different types of aerosol-generating article. The aerosol-generating element finds particular application in planar or flat aerosol-generating articles, which offer more efficient heating and generation of aerosol due to the flat structure of the aerosol-generating substrate.

[0018] The discrete, solid form of aerosol-generating element also facilitates the handling of the aerosol-generating element during manufacture of aerosol-generating articles compared to aerosol-generating substrates in the form of loose shreds, such as cut filler.

[0019] In some cases, the aerosol-generating element may be used without the need for a wrapper, which not only simplifies the manufacturing process but also reduces the environmental impact of the aerosol-generating element.

[0020] Furthermore, the use of cut filler comprising shredded plant material minimises the processing of the plant material that is required during the production of the aerosol-generating element. In particular, the use of cut filler minimises the amount of water required for the production of the aerosol-generating element and also minimises the required drying time compared to processes for producing other aerosol-generating substrates which use plant material in a different form, such as a reconstituted form. The production of the aerosolgenerating element according to the invention can therefore be carried out in an energy and cost efficient manner.

[0021] The structure of the aerosol-generating element is non-homogeneous due to the combination of the cut filler and solid binder matrix, which advantageously enables greater control over the air flow through the aerosol-generating element. This provides a greater degree of flexibility over the ventilation patterns which can be used when the aerosol-generating element is incorporated into an aerosol-generating article.

[0022] Furthermore, the majority of the production process for producing the aerosol-generating element according to the invention can be carried out with existing apparatus and methods for producing and processing cut filler, with only minor modifications required in order to incorporate the binder into the aerosol-generating element together with the cut filler.

[0023] As described above, the aerosol-generating element according to the present invention comprises cut filler, which is dispersed through the solid binder matrix. As used herein, the term “cut filler” describes 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. During the process of producing cut filler, the shredded plant material is conditioned, typically through the application of aerosol former and steam and then the conditioned plant material is dried to a defined moisture level. The cut filler may also comprise other after-cut, filler tobacco or casing, which are typically combined with the dried, conditioned plant material in an after-cut cylinder. For the purposes of the present invention, the term “cut filler” refers to the shredded plant material after it has been subjected to the conditioning and drying steps, and after it has been combined with after-cut and any other additives in the after-cut cylinder.

[0024] The cut filler of the aerosol-generating element of the present invention comprises shredded plant material which is impregnated with aerosol former. As described above, the aerosol former is applied to the plant material during the process of producing the cut filler, during a conditioning step. The aerosol former coats the shredded plant material and also penetrates the plant material to a certain extent. The aerosol former will be described in more detail below.

[0025] The aerosol-generating element preferably comprises at least 70 percent by weight of the cut filler, more preferably at least 75 percent by weight of the cut filler, more preferably at least 80 percent by weight of the cut filler, more preferably at least 85 percent by weight of the cut filler, more preferably at least 90 percent by weight of the cut filler, on a dry weight basis.

[0026] The aerosol-generating element may comprise less than or equal to 99 percent by weight of the cut filler, or less than or equal to 98 percent by weight of the cut filler, on a dry weight basis. The total weight of the cut filler includes the combined weight of the shredded plant material, the aerosol former which has been applied to the shredded plant material and any additional additives or add-backs applied during the cut filler production process.

[0027] The shredded plant material forming the cut filler has an average cut width of at least 0.75 millimetres. Preferably, the shredded plant material has an average cut width of at least 0.8 millimetres, more preferably at least 0.85 millimetres, more preferably at least 0.9 millimetres.

[0028] Preferably, the shredded plant material forming the cut filler has an average cut width of less than or equal to 2 millimetres, more preferably less than or equal to 1.75 millimetres, more preferably less than or equal to 1.5 millimetres, more preferably less than or equal to 1.25 millimetres.

[0029] For example, the shredded plant material may have an average cut width of between 0.75 millimetres and 2 millimetres, or between 0.8 millimetres and 1.75 millimetres, or between 0.85 millimetres and 1.5 millimetres, or between 0.9 millimetres and 1.25 millimetres. In one preferred embodiment, the shredded plant material has an average cut width of approximately 1 millimetre.

[0030] Preferably, the cut filler comprises at least 25 percent of plant leaf lamina, more preferably, at least 50 percent of plant leaf lamina, still more preferably at least 75 percent of plant leaf lamina and most preferably at least 90 percent of plant leaf lamina.

[0031] The shredded plant material in the cut filler may comprise shredded tobacco. With reference to the present invention, the term “tobacco” describes any plant member of the genus Nicotiana. The shredded tobacco may include tobacco material from one or more of Bright tobacco, dark tobacco, aromatic tobacco and filler tobacco. The shredded tobacco preferably comprises at least 50 percent by weight of shredded tobacco lamina, more preferably at least 75 percent of shredded tobacco lamina and most preferably at least 90 percent of shredded tobacco lamina.

[0032] In certain embodiments of the invention, the shredded plant material may consist of shredded tobacco material.

[0033] Alternatively or in addition to shredded tobacco, the shredded plant material may comprise shredded non-tobacco material. For example, the shredded plant material may comprise one or more of: tea, coffee, star anise, lavender, clove, peppermint, chamomile, rosemary, eucalyptus, ginger, dill seed, thyme, oregano and cumin.

[0034] In certain embodiments, the cut filler may comprise a combination of shredded tobacco and shredded non-tobacco material. In alternative embodiments, the cut filler may be substantially free from tobacco material such that the aerosol-generating element is tobacco free.

[0035] The cut filler preferably comprises at least 15 percent by weight of aerosol former, on a dry weight basis, based on the total weight of the cut filler. This corresponds to the proportion of aerosol former that is applied to the shredded plant material during the production of the cut filler. Additional aerosol former may or may not be added during the step of combining the cut filler with the binder.

[0036] Preferably, the cut filler comprises at least 16 percent by weight of aerosol former, more preferably at least 17 percent by weight of aerosol former, on a dry weight basis based on the total weight of the cut filler.

[0037] The cut filler preferably comprises less than or equal to 30 percent by weight of aerosol former, more preferably less than or equal to 25 percent by weight of aerosol former, more preferably less than or equal to 20 percent by weight of aerosol former, on a dry weight basis based on the total weight of the cut filler.

[0038] For example, the cut filler may comprise between 16 percent and 30 percent by weight of aerosol former, or between 17 percent and 25 percent by weight of aerosol former, or between 17 percent and 20 percent by weight of aerosol former, on a dry weight basis based on the total weight of the cut filler. In one preferred embodiment of the invention, the cut filler comprises approximately 18 percent by weight of aerosol former, on a dry weight basis based on the total weight of the cut filler.

[0039] The amount of aerosol former in the aerosol-generating element corresponds to at least 10 percent by weight, on a dry weight basis. Preferably, the aerosol-generating element comprises at least 12 percent by weight of aerosol former, more preferably at least 15 percent by weight of aerosol former, on a dry weight basis.

[0040] Preferably, the aerosol-generating element comprises less than or equal to 40 percent by weight of aerosol former, more preferably less than or equal to 30 percent by weight of aerosol former, more preferably less than or equal to 25 percent by weight of aerosol former, more preferably less than or equal to 20 percent by weight, on a dry weight basis.

[0041] For example, the aerosol-generating element may comprise between 10 percent and 40 percent by weight of aerosol former, or between 12 percent and 30 percent by weight of aerosol former, or between 15 percent and 25 percent by weight of aerosol former, or between 15 percent and 20 percent by weight of aerosol former, on a dry weight basis.

[0042] Suitable aerosol formers for use in the manufacture of aerosol-generating elements according to the present disclosure include, but are not limited to, glycerin, propylene glycol, and mixtures thereof. Preferably, the aerosol-generating element comprises at least 10 percent by weight of glycerin, on a dry weight basis, more preferably at least 12 percent by weight of glycerin, more preferably at least 15 percent by weight of glycerin, on a dry weight basis.

[0043] Preferably, the aerosol-generating element comprises less than or equal to 40 percent by weight of glycerin, more preferably less than or equal to 30 percent by weight of glycerin, more preferably less than or equal to 25 percent by weight of glycerin, more preferably less than or equal to 20 percent by weight, on a dry weight basis.

[0044] For example, the aerosol-generating element may comprise between 10 percent and 40 percent by weight of glycerin, or between 12 percent and 30 percent by weight of glycerin, or between 15 percent and 25 percent by weight of glycerin, or between 15 percent and 20 percent by weight of glycerin, on a dry weight basis.

[0045] As described above, in the aerosol-generating element of the present invention, the cut filler is dispersed within a solid binder matrix. The solid binder matrix therefore provides a matrix structure to support and bind the cut filler. This structure enables the aerosol-generating element to have a relatively high porosity and a relatively low density, as described in more detail below. Preferably, the solid binder matrix is substantially continuous.

[0046] The solid binder matrix is formed of at least one binder. The amount of binder in the aerosol-generating element should be sufficient that the cut filler can be bound together to form the aerosol-generating element. However, the amount of binder can be adapted depending on the nature of the binder, as well as the desired properties of the aerosol-generating element, such as the desired density.

[0047] According to the invention, the aerosol-generating element comprises at least 1 percent by weight of the binder, on a dry weight basis. Preferably, the aerosol-generating element comprises at least 2 percent by weight of the binder, more preferably at least 5 percent by weight of the binder, more preferably at least 7 percent by weight of the binder, more preferably at least 10 percent by weight of the binder, on a dry weight basis.

[0048] The aerosol-generating element preferably comprises less than or equal to 30 percent by weight of the binder, more preferably less than or equal to 25 percent by weight of the binder, more preferably less than or equal to 20 percent by weight of the binder, more preferably less than or equal to 15 percent by weight of the binder, on a dry weight basis.

[0049] For example, the aerosol-generating element may comprise between 1 percent and 30 percent by weight of the binder, or between 2 percent and 25 percent by weight of the binder, or between 5 percent and 20 percent by weight of the binder, or between 7 percent and 15 percent by weight of the binder, or between 10 percent and 20 percent by weight of the binder, on a dry weight basis.

[0050] Preferably, the weight ratio of the cut filler to the binder in the aerosol-generating element is at least 3, more preferably at least 4, more preferably at least 5, more preferably at least 7, more preferably at least 10, on a dry weight basis. The weight ratio of the cut filler to the binder may be less than or equal to 99, preferably less than or equal to 95, more preferably less than or equal to 90.

[0051] Suitable binders for use in the aerosol-generating element of the present invention would be known to the skilled person. The solid binder matrix may be formed with a single binder, or a combination of two or more binders.

[0052] In certain preferred embodiments of the present invention, the binder comprises polyvinyl alcohol. For example, the aerosol-generating element of the present invention may comprise between 5 percent and 20 percent by weight of polyvinyl alcohol, or between 5 percent and 15 percent by weight of polyvinyl alcohol, on a dry weight basis.

[0053] Alternatively or in addition to the polyvinyl alcohol, the binder may comprise one or more hydrocolloids. Preferably, the one or more hydrocolloids are selected from the group consisting of: starch, modified starch, dextrin, alginate, pectin, cellulose, cellulose derivatives (such as carboxymethyl cellulose), agar, carrageenan, gelatin, natural gums (such as tragancanth gum, konjac gum, guar gum or xanthan gum) and combinations thereof.

[0054] In certain preferred embodiments of the present invention, the binder comprises nanocellulose, such as cellulose nanocrystals (also known as nanocrystalline cellulose) or microfibri Hated cellulose.

[0055] The aerosol-generating element of the present invention may comprise between 1 percent and 15 percent by weight of nanocellulose, or between 2 percent and 10 percent by weight of nanocellulose, or between 2 and 8 percent by weight of nanocellulose, on a dry weight basis.

[0056] For example, the aerosol-generating element may comprise between 1 percent and 15 percent by weight of cellulose nanocrystals, or between 2 percent and 10 percent by weight of cellulose nanocrystals, or between 2 and 8 percent by weight of cellulose nanocrystals, on a dry weight basis.

[0057] Alternatively, or in addition, the aerosol-generating element may comprise between 1 percent and 10 percent by weight of m icrof i bri I lated cellulose, or between 2 percent and 8 percent by weight of microfibri I lated cellulose, or between 2 percent and 6 percent by weight of microfibri I lated cellulose, or between 2 percent and 4 percent by weight of microfibri I lated cellulose, on a dry weight basis.

[0058] In certain embodiments, the binder comprises a combination of polyvinyl alcohol and nanocellulose. The ratio of polyvinyl alcohol to nanocellulose may be at least 1 , or at least 2, or at least 3.

[0059] The aerosol-generating element according to the present invention may further comprise one or more active agents. For example, the aerosol-generating element may comprise exogenous nicotine. The term “exogenous nicotine” refers to nicotine that is added to the aerosolgenerating element as a distinct component from any nicotine that is intrinsically present in the shredded plant material, for example, where the shredded plant material comprises shredded tobacco. The total nicotine content of the aerosol-generating element is preferably between 1 percent by weight and 5 percent by weight, more preferably between 1 percent by weight and 3 percent by weight, on a dry weight basis. The total nicotine content corresponds to the total combined amount of intrinsic nicotine which may be present in tobacco material and any exogenous nicotine that is added instead of, or in addition to, shredded tobacco.

[0060] Alternatively or in addition, the aerosol-generating element of the present invention may comprise one or more cannabinoid compounds selected from the group consisting of: tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), cannabidiol (CBD), cannabidiolic acid (CBDA), cannabinol (CBN), cannabigerol (CBG), cannabigerol monomethyl ether (CBGM), cannabivarin (CBV), cannabidivarin (CBDV), tetrahydrocannabivarin (THCV), cannabichromene (CBC), cannabicyclol (CBL), cannabichromevarin (CBCV), cannabigerovarin (CBGV), cannabielsoin (CBE), cannabicitran (CBT) and combinations thereof. Preferably, the one or more cannabinoid compounds are selected from CBD, THC and a combination thereof. Particularly preferably, the one or more cannabinoid compounds includes CBD.

[0061] Alternatively or in addition, the aerosol-generating element of the present invention may further comprise one or more flavourants. Suitable flavourants would be known to the skilled person. The one or more flavourants may comprise one or more of: one or more essential oils such as eugenol, peppermint oil and spearmint oil; one or both of menthol and eugenol; one or both of anethole and linalool.

[0062] The aerosol-generating element preferably has a total water content of less than or equal to 30 percent by weight, more preferably less than or equal to 20 percent by weight, more preferably less than or equal to 15 percent by weight.

[0063] The aerosol-generating element preferably has a total water content of at least 1 percent by weight, more preferably at least 2 percent by weight, more preferably at least 5 percent by weight.

[0064] For example, the aerosol-generating element may have a total water content of between 1 percent and 30 percent by weight, or between 2 percent and 20 percent by weight, or between 5 percent and 15 percent by weight.

[0065] Preferably, the aerosol-generating element has a moisture content of less than or equal to 30 percent oven volatiles (OV), more preferably less than or equal to 20 percent oven volatiles (OV), more preferably less than or equal to 15 percent oven volatiles (OV).

[0066] Preferably, the aerosol-generating element has a moisture content of at least 1 percent oven volatiles (OV), more preferably at least 2 percent oven volatiles (OV), more preferably at least 5 percent oven volatiles (OV).

[0067] For example, the aerosol-generating element may have a moisture content of between 1 percent and 30 percent OV, or between 2 percent and 20 percent OV, or between 5 percent and 15 percent OV. The term “percent oven volatiles” (percent OV) is used to refer to the moisture content of a material. It is determined by measuring the percentage weight loss from the material being tested upon drying a sample of the material in an oven at 100 plus or minus 1 degree Celsius (°C) for 3 hours plus or minus 0.5 minutes. In practice, it is assumed that a significant majority of the weight loss from plant material results from the evaporation of moisture. It should be noted that, on an absolute basis, the values of moisture content determined by oven drying may be greater than the results of water content analysis when using a specific method such as ISO 6488 (Karl Fischer method). The difference is sample-type dependent and is due to the loss of volatile materials other than water, (for example, aerosol former) from the tested material during oven drying.

[0068] According to the present invention, the aerosol-generating element has an average density of less than or equal to 420 mg per cubic centimetre. Preferably, the aerosol-generating element has an average density of less than or equal to 400 mg per cubic centimetre, more preferably less than or equal to 375 mg per cubic centimetre, more preferably less than or equal to 350 mg per cubic centimetre, more preferably less than or equal to 325 mg per cubic centimetre, more preferably less than or equal to 300 mg per cubic centimetre.

[0069] The aerosol-generating element preferably has an average density of at least 200 mg per cubic centimetre, more preferably at least 225 mg per cubic centimetre, more preferably at least 250 mg per cubic centimetre.

[0070] For example, the aerosol-generating element may have an average density of between 200 mg per cubic centimetre and 420 mg per cubic centimetre, or between 200 mg per cubic centimetre and 400 mg per cubic centimetre, or between 225 mg per cubic centimetre and 375 mg per cubic centimetre, or between 225 mg per cubic centimetre and 350 mg per cubic centimetre, or between 250 mg per cubic centimetre and 325 mg per cubic centimetre, or between 250 mg per cubic centimetre and 300 mg per cubic centimetre.

[0071] The average density can be calculated by measuring the weight of an aerosol-generating element and dividing this weight by the volume occupied by the aerosol-generating element.

[0072] The porous aerosol-generating element advantageously has a relatively low density, due to the porous structure of the cut filler dispersed within the solid binder matrix. The relatively low density enables a more efficient transfer of heat through the aerosol-generating element during use. This, in turn, enables a more efficient generation of aerosol from the cut filler upon heating. The provision of a relatively low density also enables a greater degree of airflow through the aerosol-generating element, which may additionally improve the uniformity of heating of the aerosol-generating element during use.

[0073] The aerosol-generating elements of the present invention have a porous structure, with a plurality of air filled pores within the structure defined by the solid binder matrix and the cut filler.

[0074] Preferably, the aerosol-generating element has a total porosity of at least 0.3, more preferably at least 0.35, more preferably at least 0.4. Preferably, the aerosol-generating element has a total porosity of less than or equal to 0.7, preferably less than or equal to 0.65, preferably less than or equal to 0.6.

[0075] For example, the aerosol-generating element may have a total porosity of between 0.3 and 0.7, or between 0.35 and 0.65, or between 0.4 and 0.6.

[0076] As used herein, the term “total porosity” refers to a ratio of the total void space in a porous body to the overall volume of that porous body. Specifically, the total porosity of the aerosolgenerating element corresponds to the total volume of the pores within the aerosol-generating element, divided by the total volume of the aerosol-generating element. The total pore volume takes into account both open pores and closed pores, which are discussed below.

[0077] The porous structure of the aerosol-generating element includes open pores, which are connected with the external environment of the aerosol-generating element and closed pores, which are not connected with the external environment. Both of these types of pores are taken into account in the measurement of the total porosity as described above.

[0078] Preferably, the open porosity of the aerosol-generating element is at least 0.3, more preferably at least 0.35, more preferably at least 0.4. Preferably, the open porosity of the aerosolgenerating element is less than or equal to 0.6, more preferably less than or equal to 0.55, more preferably less than or equal to 0.5. For example, the open porosity of the aerosol-generating element may be between 0.3 and 0.6, or between 0.35 and 0.55, or between 0.4 and 0.5.

[0079] The “open porosity” refers to a ratio of the total void space of the open pores within a porous body to the overall volume of that porous body. This value of porosity can be measured and calculated as described above in relation to the total porosity, but taking into account only the open pores within the structure.

[0080] The total porosity and open porosity of the aerosol-generating element may be determined using an industrial computed tomography system. For the purposes of the present invention, the total porosity and open porosity of the aerosol-generating element were measured in a Nikon XTH 225 ST industrial computed tomography system from Nikon Metrology NV, which was operated with the following parameters:

[0081] Beam energy: 150kV

[0082] Beam current: 36 microamps

[0083] Power: 5.4W

[0084] Projections: 3141

[0085] Exposure time: 708 ms

[0086] The scan obtained from this system was reconstructed in 3D using the “CT Pro 3D” software from Nikon Metrology NV and the 3D data was analysed using the software “VG Studio Max” from Volume Graphics. This software enabled the calculation of the total volume of open pores, the total volume of closed pores and therefore the total overall volume of pores. Using the volume of the aerosol-generating element, the total porosity and open porosity can then be calculated as set out above. The aerosol-generating element may optionally include one or more perforations in order to provide a greater degree of airflow through the aerosol-generating element.

[0087] The size and shape of the aerosol-generating element may be adapted depending on the intended use of the aerosol-generating element, for example, depending on the construction of the aerosol-generating element into which the aerosol-generating element may be incorporated.

[0088] Preferably, the weight of the aerosol-generating element according to the invention is at least 50 mg, more preferably at least 100 mg, more preferably at least 125 mg, more preferably at least 150 mg.

[0089] Preferably, the weight of the aerosol-generating element is less than or equal to 300 mg, more preferably less than or equal to 250 mg, more preferably less than or equal to 200 mg.

[0090] For example, the weight of the aerosol-generating element may be between 50 mg and 300 mg, or between 100 mg and 250 mg, or between 125 mg and 250 mg, or between 100 mg and 200 mg, or between 125 mg and 200 mg, or between 150 mg and 200 mg.

[0091] The aerosol-generating element is defined by a length measured in the x direction, a width measured in the y direction and a thickness measured in z direction. The length is typically greater than or equal to the width. The thickness is typically less than or equal to the length and width. Preferably, the thickness is less than the length and the width.

[0092] For the purposes of the present invention, the thickness of the aerosol-generating element should be considered to be the smallest of the three dimensions measured in the x, y and z directions.

[0093] Preferably, the length and width of the aerosol-generating element are at least twice the thickness of the aerosol-generating element.

[0094] Preferably, the average thickness of the aerosol-generating element according to the present invention is at least 1 millimetre, more preferably at least 1.5 millimetres, more preferably at least 2 millimetres. Preferably, the average thickness of the aerosol-generating element is less than or equal to 15 millimetres, more preferably less than or equal to 10 millimetres, more preferably less than or equal to 5 millimetres. For example, the average thickness of the aerosolgenerating element may be between 1 millimetre and 15 millimetres, or between 1.5 millimetres and 10 millimetres, or between 2 millimetres and 5 millimetres. In one preferred embodiment, the aerosol-generating element has an average thickness of approximately 3 millimetres.

[0095] The thickness of the aerosol-generating element may be substantially constant along the full length and width of the aerosol-generating element. Alternatively, the thickness of the aerosolgenerating element may vary.

[0096] Preferably, the average thickness of the aerosol-generating element is at least twice the average cut width of the cut filler, as defined above, more preferably at least 2.5 times the average cut width of the cut filler, more preferably at least 3 times the average cut width of the cut filler. This ensures that the aerosol-generating element has sufficient structural integrity and strength for use in an aerosol-generating article. Preferably, the length of the aerosol-generating element according to the present invention is at least 10 millimetres, more preferably at least 12 millimetres, more preferably at least 15 millimetres. Preferably, the length of the aerosol-generating element is less than or equal to 40 millimetres, more preferably less than or equal to 30 millimetres, more preferably less than or equal to 20 millimetres. For example, the length of the aerosol-generating element may be between 10 millimetre and 40 millimetres, or between 12 millimetres and 30 millimetres, or between 15 millimetres and 20 millimetres.

[0097] Preferably, the width of the aerosol-generating element according to the present invention is at least 4 millimetres, more preferably at least 5 millimetres, more preferably at least 6 millimetres. Preferably, the width of the aerosol-generating element is less than or equal to 15 millimetres, more preferably less than or equal to 12 millimetres, more preferably less than or equal to 10 millimetres. For example, the length of the aerosol-generating element may be between 4 millimetre and 15 millimetres, or between 5 millimetres and 12 millimetres, or between 6 millimetres and 10 millimetres.

[0098] Preferably, the length of the aerosol-generating element is at least twice the thickness, more preferably at least three times the thickness, more preferably at least four times the thickness.

[0099] Preferably, the width of the aerosol-generating element is at least 1 .5 times the thickness, more preferably at least 1 .75 times the thickness, more preferably at least twice the thickness.

[0100] The aerosol-generating element may therefore preferably have a relatively flat form, with a thickness that is significantly smaller than the length and width.

[0101] In certain preferred embodiments, the aerosol-generating element comprises opposed planar surfaces. For example, the aerosol-generating element may comprise planar upper and lower surfaces, wherein the separation between the upper and lower surfaces corresponds to the thickness of the aerosol-generating element. The provision of opposed planar surfaces may be advantageous if the aerosol-generating element is intended to be used in an aerosol-generating device comprising planar heater elements, in order to maximise contact between the planar heating elements and the aerosol-generating element.

[0102] Where the aerosol-generating element comprises opposed planar surfaces, the exposed surface area of each planar surface is preferably at least 100 square millimetres, more preferably at least 125 square millimetres, more preferably at least 150 square millimetres. The exposed surface area of each exposed planar surface may be less than or equal to 600 square millimetres, or less than or equal to 500 square millimetres.

[0103] The total exposed surface area of the aerosol-generating element according to the invention is preferably at least 150 square millimetres, more preferably at least 250 square millimetres, more preferably at least 350 square millimetres, more preferably at least 400 square millimetres. The total exposed surface area of the aerosol-generating element may be less than or equal to 2500 square millimetres, or less than or equal to 1500 square millimetres, or less than or equal to 1000 square millimetres.

[0104] The aerosol-generating element may have any suitable shape, depending on the desired use of the aerosol-generating element. The aerosol-generating element may be in the shape of a rectangular cuboid, or a lozenge. Alternatively, the aerosol-generating element

[0105] As defined above, the present invention further provides a method for the production of an aerosol-generating element according to the invention, as defined above. The method according to the invention comprises the steps of: providing a plant material; conditioning the plant material, wherein the conditioning includes applying an aerosol former to the plant material, wherein the amount of aerosol former applied to the plant material corresponds to at least 15 percent by weight on a dry weight basis, based on the weight of the plant material; cutting the plant material to a provide a shredded plant material with an average cut width of at least 0.75mm; drying the conditioned plant material to provide a cut filler having a defined moisture level; adding a binder solution comprising one or more binders to the cut filler and mixing the binder solution and the cut filler to at least partially coat the cut filler with the binder solution; compacting the mixture of binder solution and cut filler; drying the compacted mixture to form a solid substrate comprising a solid binder matrix having the cut filler dispersed through it; and forming a discrete porous aerosol-generating element from the solid substrate.

[0106] The plant material may be a tobacco or non-tobacco material, or a combination thereof, as described above.

[0107] In the conditioning step, an aerosol former is applied to the plant material. The aerosol former is preferably applied at an elevated temperature, for example a temperature of between 40 degrees Celsius and 100 degrees Celsius. The aerosol former may be applied in a mixture with steam. Additional additives, such as casings may additionally be applied to the plant material in the conditioning step. The conditioning step may be carried out in the Direct Conditioning Casing Cylinder (DCCC), under the same conditions as would be used in a conventional cut filler production process.

[0108] The amount of aerosol former applied to the plant material is adapted such that the final cut filler includes an amount of at least 15 percent by weight of aerosol former, on a dry weight basis.

[0109] In the cutting step, the plant material is cut to provide a shredded plant material having an average cut width of at least 0.75 millimetres. The cutting step is preferably carried out after the conditioning step, although it may alternatively be carried out before the conditioning step. The cutting step may be carried out using conventional means, as would be used in a conventional cut filler production process.

[0110] The conditioned plant material is subsequently dried to a defined moisture level. This may be carried out by conventional means, for example, in a flash tower dryer. The drying temperature will depend upon the nature of the plant material and the desired moisture level. It may be between 100 degrees Celsius and 350 degrees Celsius, for example between 150 degrees Celsius and 250 degrees Celsius.

[0111] The conditioned plant is preferably dried to a moisture content of between 1 percent oven volatiles (OV) and 20 percent OV, more preferably between 5 percent OV and 15 percent OV, more preferably between 5 percent OV and 10 percent OV.

[0112] After the drying step, the dried, conditioned plant material may be mixed with at least one additive or add-back, for example, a flavourant or casing. This mixing may take place in the aftercut cylinder, as would be used in a conventional cut filler production process.

[0113] The resultant product from these steps is a cut filler as described above, including shredded plant material impregnated with an aerosol former.

[0114] In order to provide an aerosol-generating element having a solid binder matrix, as defined above, the cut filler is combined with a binder solution comprising at least one binder. The binder solution is applied to the cut filler, for example by spraying, and the cut filler and binder solution are mixed in order to at least partially coat the cut filler with the binder solution. The binder solution may be a solution of the binder in water, aerosol former, or another solvent. The concentration of the binder in the binder solution may be adapted, depending on the nature of the binder. Preferably, the amount of water or other solvent used in the binder solution is minimised to as to reduce the time and energy requirements for the subsequent drying steps.

[0115] Advantageously, the binder solution may be applied to the cut filler in the after-cut cylinder, such that this step can be carried out without significant modification to the existing cut filler production process and apparatus. Alternatively, the binder solution may be applied to the cut filler in a separate step, downstream of the after-cut cylinder. For example, the cut filler may be deposited from the after-cut cylinder as a layer on a continuous surface and the binder solution may be sprayed onto the layer of cut filler.

[0116] The mixture of the cut filler and binder solution is then compacted and the compacted mixture is dried to form a solid substrate comprising a solid binder matrix having the cut filler dispersed through it. The step of compacting the mixture of cut filler and binder solution may be carried out using any suitable means. In some embodiments, the compaction may be carried out by pressing the mixture, for example, using a compression plate or by passing the mixture through one or more pairs of rollers. Alternatively, the compaction may be carried out by extrusion of the mixture.

[0117] The degree of compaction is adapted in order to provide an aerosol-generating element having the desired density and porosity. Upon drying of the mixture of cut filler and binder solution, the binder forms a solid matrix around the cut filler, which binds the cut filler together to form a solid substrate. From this solid substrate, one or more discrete aerosol-generating elements can be formed. This may be carried out, for example, by cutting of the solid substrate to the desired shape and size. In alternative methods, the mixture of cut filler and binder solution can be formed into the desired shape and size (for example, by extrusion) prior to the final drying step.

[0118] Aerosol-generating elements according to the present invention may be used in a wide variety of different aerosol-generating articles. As defined below, the present invention provides an aerosol-generating article comprising an aerosol-generating substrate, the aerosol-generating substrate comprising one or more porous aerosol-generating elements according to the present invention, as described above.

[0119] Preferably, the aerosol-generating substrate comprises a plurality of porous aerosolgenerating elements as described above.

[0120] Preferably, the average bulk density of the aerosol-generating substrate is less than or equal to 420 mg per cubic centimetre. Preferably, the aerosol-generating substrate has an average bulk density of less than or equal to 400 mg per cubic centimetre, more preferably less than or equal to 375 mg per cubic centimetre, more preferably less than or equal to 350 mg per cubic centimetre, more preferably less than or equal to 325 mg per cubic centimetre, more preferably less than or equal to 300 mg per cubic centimetre.

[0121] The aerosol-generating substrate preferably has an average bulk density of at least 200 mg per cubic centimetre, more preferably at least 225 mg per cubic centimetre, more preferably at least 250 mg per cubic centimetre.

[0122] For example, the aerosol-generating substrate may have an average bulk density of between 200 mg per cubic centimetre and 420 mg per cubic centimetre, or between 200 mg per cubic centimetre and 400 mg per cubic centimetre, or between 225 mg per cubic centimetre and 375 mg per cubic centimetre, or between 225 mg per cubic centimetre and 350 mg per cubic centimetre, or between 250 mg per cubic centimetre and 325 mg per cubic centimetre, or between 250 mg per cubic centimetre and 300 mg per cubic centimetre.

[0123] The average bulk density of the aerosol-generating substrate can be calculated by measuring the total weight of the aerosol-generating substrate and dividing this weight by the volume occupied by the aerosol-generating substrate in the aerosol-generating article.

[0124] The aerosol-generating substrate advantageously has a relatively low bulk density. The relatively low bulk density enables a more efficient transfer of heat through the aerosol-generating substrate during use. This, in turn, enables a more efficient generation of aerosol from the aerosol-generating elements upon heating. The provision of a relatively low bulk density also enables a greater degree of airflow through the aerosol-generating substrate, which may additionally improve the uniformity of heating of the aerosol-generating substrate during use. The aerosol-generating substrate comprising the one or more porous aerosol-generating elements may be combined with one or more elements upstream or downstream of the aerosolgenerating substrate.

[0125] The aerosol-generating article has an article length, an article width and an article thickness, wherein the article length and the article width are preferably at least twice the article thickness.

[0126] Preferably, the aerosol-generating article according to the invention is substantially flat, or substantially planar. This means that the article has a relatively large base area relative to the volume of the article. As described above, the aerosol-generating element of the present invention has been found to be particularly suitable for use in flat aerosol-generating articles since it can readily be formed in a flat shape with relatively large opposed surfaces. This form optimises heating of the aerosol-generating element and the generation of aerosol. The thickness of the aerosol-generating element can be relatively small, allowing a smaller temperature gradient across the thickness of the aerosol-generating element during heating.

[0127] In certain preferred embodiments of the present invention, the aerosol-generating article comprises: a first planar external surface; a second planar external surface; a cavity; a frame positioned between the first planar external surface and the second planar external surface, the frame at least partially defining the cavity; an air inlet and an air outlet; and an airflow passage extending between the air inlet and the air outlet through the cavity. The one or more porous aerosol-generating elements are positioned between the first planar external surface and the second planar external surface, typically within the cavity.

[0128] The cavity may comprise a single aerosol-generating element, which has a size and shape adapted to sit within the cavity. Alternatively, the cavity may contain a plurality of aerosolgenerating elements, wherein each aerosol-generating element has dimensions that are significantly smaller than the dimensions of the cavity.

[0129] In alternative preferred embodiments of the present invention, the aerosol-generating article comprises a container, the container comprising a first wall and a second wall together defining a substrate compartment, wherein the one or more porous aerosol-generating elements are provided in the substrate compartment.

[0130] The first wall may comprise a different material to the second wall. This provision may advantageously allow the first and second wall to have different properties tailored for different functions. For example, the first and second walls may be configured to have different porosities, different thermal conductivities, or different stiffnesses.

[0131] The first wall may comprise a flexible material, such as a flexible cellulosic material. The second wall may have a higher stiffness than the first wall.

[0132] At least a portion of the first or second wall may be porous.

[0133] The container as defined above may be in the form of a pouch. Below, there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0134] EX1. A porous aerosol-generating element for generating an inhalable aerosol upon heating, the porous aerosol-generating element comprising: a solid binder matrix comprising at least one binder; and cut filler dispersed within the solid binder matrix, the cut filler comprising shredded plant material impregnated with an aerosol former.

[0135] EX2. A porous aerosol-generating element according to example EX1 , wherein the shredded plant material has an average cut width of at least 0.75 millimetres.

[0136] EX3. A porous aerosol-generating element according to example EX1 or EX2, wherein the shredded plant material has an average cut width of at least 0.8 millimetres, for example at least 0.85 millimetres, for example at least 0.9 millimetres.

[0137] EX4. A porous aerosol-generating element according to any preceding example, wherein the shredded plant material has an average cut width of less than or equal to 2 millimetres, for example less than or equal to 1.75 millimetres, for example less than or equal to 1 .5 millimetres, for example less than or equal to 1 .25 millimetres.

[0138] EX5. A porous aerosol-generating element according to any preceding example, wherein the shredded plant material comprises shredded tobacco.

[0139] EX6. A porous aerosol-generating element according to example EX5, wherein the shredded tobacco comprises at least 50 percent by weight of shredded tobacco lamina.

[0140] EX7. A porous aerosol-generating element according to any preceding example, wherein the shredded plant material comprises shredded non-tobacco plant material.

[0141] EX8. A porous aerosol-generating element according to example EX7, wherein the shredded non-tobacco plant material comprises one or more of: tea, star anise, lavender, clove, peppermint, chamomile, rosemary, eucalyptus, ginger, dill seed, thyme, oregano and cumin.

[0142] EX9. A porous aerosol-generating element according to any preceding example, wherein the cut filler comprises at least 15 percent by weight of aerosol former, for example at least 16 percent by weight of aerosol former, for example at least 17 percent by weight on a dry weight basis based on the total weight of the cut filler.

[0143] EX10. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises at least 70 percent by weight of the cut filler, for example at least 80 percent by weight of the cut filler, for example at least 90 percent by weight of the cut filler, on a dry weight basis.

[0144] EX11. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises at least 10 percent by weight of the aerosol former, on a dry weight basis. EX12. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises at least 12 percent by weight of the aerosol former, for example at least 15 percent by weight of the aerosol former, on a dry weight basis.

[0145] EX13. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises less than or equal to 40 percent by weight of the aerosol former, for example less than or equal to 30 percent by weight of the aerosol former, for example less than or equal to 25 percent by weight of the aerosol former, for example less than or equal to 20 percent by weight of the aerosol former, on a dry weight basis.

[0146] EX14. A porous aerosol-generating element according to any preceding example, wherein the aerosol former comprises glycerin, propylene glycol or a combination thereof.

[0147] EX15. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises at least 1 percent by weight of the binder, on a dry weight basis.

[0148] EX16. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises at least 2 percent by weight of the binder, for example at least 5 percent by weight of the binder, for example at least 7 percent by weight of the binder, for example at least 10 percent by weight of the binder on a dry weight basis.

[0149] EX17. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises less than or equal to 30 percent by weight of the binder, for example less than or equal to 25 percent by weight of the binder, for example less than or equal to 20 percent by weight of the binder, for example less than or equal to 15 percent by weight of the binder, on a dry weight basis.

[0150] EX18. A porous aerosol-generating element according to any preceding example, wherein the weight ratio of the cut filler to the binder is at least 3, for example at least 4, for example at least 5, for example at least 7, for example at least 10, on a dry weight basis.

[0151] EX19. A porous aerosol-generating element according to any preceding example, wherein the binder comprises polyvinyl alcohol.

[0152] EX20. A porous aerosol-generating element according to example EX19, wherein the porous aerosol-generating element comprises between 5 percent and 20 percent by weight of polyvinyl alcohol, for example between 5 percent and 15 percent by weight of polyvinyl alcohol, on a dry weight basis.

[0153] EX21. A porous aerosol-generating element according to any preceding example, wherein the binder comprises one or more hydrocolloids.

[0154] EX22. A porous aerosol-generating element according to any example EX21 , wherein the one or more hydrocolloids are selected from: starch, modified starch, alginate, pectin, cellulose, cellulose derivatives, dextrin, agar, carrageenan, gelatin, natural gums and combinations thereof. EX23. A porous aerosol-generating element according to any preceding example, wherein the binder comprises nanocellulose.

[0155] EX24. A porous aerosol-generating element according to example EX23, wherein the porous aerosol-generating element comprises between 1 percent and 15 percent by weight of nanocellulose, for example between 2 percent and 10 percent by weight of nanocellulose, for example between 2 and 8 percent by weight of nanocellulose, on a dry weight basis.

[0156] EX25. A porous aerosol-generating element according to any preceding example, wherein the binder comprises a polyvinyl alcohol, nanocellulose or a combination thereof.

[0157] EX26. A porous aerosol-generating element according to example EX23, wherein the binder comprises microfibri Hated cellulose.

[0158] EX27. A porous aerosol-generating element according to example EX23, wherein the porous aerosol-generating element comprises cellulose nanocrystals.

[0159] EX28. A porous aerosol-generating element according to any preceding example, wherein the solid binder matrix is substantially continuous.

[0160] EX29. A porous aerosol-generating element according to any preceding example, further comprising an active agent, for example exogenous nicotine.

[0161] EX30. A porous aerosol-generating element according to any preceding example, further comprising a flavourant.

[0162] EX31. A porous aerosol-generating element according to any preceding example, wherein the total water content of the porous aerosol-generating element is less than or equal to 30 percent by weight, for example less than or equal to 15 percent by weight, for example less than or equal to 12 percent by weight.

[0163] EX32. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has a moisture content of less than or equal to 30 percent oven volatiles, for example less than or equal to 15 percent oven volatiles, for example less than or equal to 12 percent oven volatiles.

[0164] EX33. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has a total nicotine content of between 1 percent and 5 percent by weight, for example between 1 percent and 3 percent by weight, on a dry weight basis.

[0165] EX34. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has an average density of less than or equal to 420 mg per cubic centimetre.

[0166] EX35. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has an average density of less than or equal to 400 mg per cubic centimetre, for example less than or equal to 375 mg per cubic centimetre, for example less than or equal to 350 mg per cubic centimetre, for example less than or equal to 325 mg per cubic centimetre, for example less than or equal to 300 mg per cubic centimetre. EX36. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has an average density of at least 200 mg per cubic centimetre.

[0167] EX37. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has a total porosity of at least 0.3, for example at least 0.35, for example at least 0.4.

[0168] EX38. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has an open porosity of at least 0.3, for example at least 0.35, for example at least 0.4.

[0169] EX39. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises one or more perforations.

[0170] EX40. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises a non-homogeneous cross-section.

[0171] EX41. A porous aerosol-generating element according to any preceding example, wherein the weight of the porous aerosol-generating element is at least 50 mg, for example at least 100 mg, for example at least 125 mg, for example at least 150 mg.

[0172] EX42. A porous aerosol-generating element according to any preceding example, wherein the weight of the porous aerosol-generating element is less than or equal to 300 mg, for example less than or equal to 250 mg, for example less than or equal to 200 mg.

[0173] EX43. A porous aerosol-generating element according to any preceding example, wherein the average thickness of the porous aerosol-generating element is at least 1 millimetre, for example at least 1.5 millimetres, for example at least 2 millimetres.

[0174] EX44. A porous aerosol-generating element according to any preceding example, wherein the average thickness of the porous aerosol-generating element is at least twice the average cut width of the cut filler, for example at least 2.5 times, for example at least 3 times.

[0175] EX45. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has a length of between 10 millimetres and 25 millimetres, for example between 15 millimetres and 20 millimetres.

[0176] EX46. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element has a width of between 5 millimetres and 15 millimetres, for example between 6 millimetres and 10 millimetres.

[0177] EX47. A porous aerosol-generating element according to any preceding example, wherein the length of the porous aerosol-generating element is at least twice the thickness, for example at least three times the thickness, for example at least four times the thickness.

[0178] EX48. A porous aerosol-generating element according to any preceding example, wherein the width of the porous aerosol-generating element is at least 1 .5 times the thickness, for example at least twice the thickness. EX49. A porous aerosol-generating element according to any preceding example, wherein the porous aerosol-generating element comprises opposed planar surfaces.

[0179] EX50. A porous aerosol-generating element according to example EX49 wherein the exposed surface area of each planar surface is at least 100 square millimetres, for example at least 125 square millimetres, for example at least 150 square millimetres.

[0180] EX51. A porous aerosol-generating element according to any preceding example, wherein the exposed surface area of the porous aerosol-generating element is at least 150 square millimetres, for example at least 250 square millimetres, for example at least 350 square millimetres, for example at least 400 square millimetres.

[0181] EX52. An aerosol-generating article comprising an aerosol-generating substrate, the aerosol-generating substrate comprising one or more porous aerosol-generating elements according to any preceding example.

[0182] EX53. An aerosol-generating article according to example EX52, wherein the aerosolgenerating article is substantially flat.

[0183] EX54. An aerosol-generating article according to example EX53, the aerosol-generating article comprising: a first planar external surface; a second planar external surface; a cavity; a frame positioned between the first planar external surface and the second planar external surface, the frame at least partially defining the cavity, wherein the one or more porous aerosol-generating elements are positioned between the first planar external surface and the second planar external surface; an air inlet and an air outlet; and an airflow passage extending between the air inlet and the air outlet through the cavity.

[0184] EX55. An aerosol-generating article according to example EX52, the aerosol-generating article comprising: a container, the container comprising a first wall and a second wall together defining a substrate compartment, wherein the one or more porous aerosol-generating elements are provided in the substrate compartment.

[0185] EX56. A method of producing a porous aerosol-generating element according to any of the examples EX1 to EX51 , the method comprising the steps of: providing a plant material; conditioning the plant material, wherein the conditioning includes applying an aerosol former to the plant material, wherein the amount of aerosol former applied to the plant material corresponds to at least 15 percent by weight on a dry weight basis, based on the weight of the plant material; cutting the plant material to a provide a shredded plant material with an average cut width of at least 0.75mm; drying the conditioned plant material to provide a cut filler having a defined moisture level; adding a binder solution comprising one or more binders to the cut filler and mixing the binder solution and the cut filler to at least partially coat the cut filler with the binder solution; compacting the mixture of binder solution and cut filler; drying the compacted mixture to form a solid substrate comprising a solid binder matrix having the cut filler dispersed through it; and forming a discrete porous aerosol-generating element from the solid substrate.

[0186] EX57. A method according to example EX56, wherein the conditioning step comprises applying a mixture of the aerosol former and steam to the plant material.

[0187] EX58. A method according to example EX56 or EX57, wherein after the drying step, the cut filler is mixed with at least one additive in an after cut cylinder.

[0188] EX59. A method according to example EX58, wherein the binder solution is applied in the after-cut cylinder.

[0189] EX60. A method according to example EX58, wherein the binder solution is applied downstream of the after-cut cylinder.

[0190] EX61. A method according to example EX58, wherein a casing solution is applied to the cut filler in the after-cut cylinder.

[0191] EX62. A method according to any of examples EX56 to EX61 , wherein the step of compacting the mixture of the cut filler and binder solution is carried out by pressing of the mixture, for example using one or more pairs of rollers.

[0192] EX63. A method according to any of examples EX56 to EX61 , wherein the step of compacting the mixture of the cut filler and binder solution is carried out by extrusion of the mixture.

[0193] Examples will now be further described with reference to the figures in which:

[0194] Figure 1 shows a perspective view of an aerosol-generating article according to a first embodiment of the invention;

[0195] Figure 2 shows an exploded perspective view of the aerosol-generating article of Figure 1 ;

[0196] Figure 3 shows a transverse cross-sectional view of the aerosol-generating article of Figure 1 ; and

[0197] Figure 4 shows a schematic cross-sectional view of an aerosol-generating article according to a second embodiment of the invention.

[0198] Figure 1 shows an aerosol-generating article 10 comprising a first planar external layer 24 forming a first planar external surface 21 , a second planar external layer 25 forming a second planar external surface 22, and a frame 50 positioned between the first planar external layer 24 and the second planar external layer 25. The first planar external layer 24 and the second planar external layer 25 may be formed from a non-aerosol forming material, such as paper or card. Alternatively, either of the first planar external layer 24 and the second planar external layer 25 may comprise an aerosol-generating substrate comprising an aerosol-generating material, for example tobacco.

[0199] The aerosol-generating article 10 has a length extending in the x-direction, a width extending in the y-direction and a thickness extending in the z-direction. The aerosol-generating article 10 has a length of 30 millimetres, a width of 10 millimetres, and a thickness of 3.1 millimetres.

[0200] The first planar external surface 21 and the second planar external surface 22 extend in the x-direction and the y-direction. That is, the first planar external surface 21 and the second planar external surface 22 extend in the x / y plane. The first planar external surface 21 is positioned parallel to the second planar external surface 22 and the first planar external surface

[0201] 21 is spaced from the second planar external surface 22 in the z-direction or transverse direction. The distance between the first planar external surface 21 and the second planar external surface

[0202] 22 in the z-direction or transverse direction corresponds to the thickness of the aerosol-generating article 10.

[0203] The aerosol-generating article 10 is a substantially flat aerosol-generating article or substantially planar aerosol-generating article. In particular, the thickness of the aerosolgenerating article 10 is less than 50 percent of both the length and the width of the aerosolgenerating article. The aerosol-generating article 10 has a generally rectangular cuboid shape and a laminated structure formed by the first planar external layer 24, the frame 50 and the second planar external layer 25. The first planar external layer 24, the frame 50 and the second planar external layer 25 are bonded together with an adhesive, in particular guar gum.

[0204] Figure 2 shows an exploded view of the aerosol-generating article 10 of Figure 1.

[0205] The frame 50 has a length of 30 millimetres, a width of 10 millimetres, and a thickness of 2.7 millimetres. The frame 50 is made from cardboard and defines a frame aperture extending through the thickness of the frame 50. The frame aperture at least partially forms a cavity 30. The cavity 30 has length of 26 millimetres, a width of 6 millimetres, and a thickness of 2.7 millimetres. Therefore, the cavity 30 has a volume of about 421.2 cubic millimetres. The cavity comprises a porous aerosol-generating element 40 positioned within the cavity 30. The porous aerosolgenerating element 40 will be described in more detail below.

[0206] The first planar external layer 24 and the second planar external layer 25 have a thickness of 200 micrometres and are in physical contact with the frame 50. The first planar external layer 24 and the second planar external layer 25 are bonded to the frame with an adhesive 15. The first planar external layer 24 overlies an end of the cavity 30 and forms a first cavity end wall 31. The second planar external layer 25 overlies an opposite end of the cavity 30 and forms a second cavity end wall 32. That is, the frame 50, the first planar external layer 24 and the second planar external layer 25 collectively define the cavity 30. The frame 50 comprises a peripheral wall 51 that circumscribes the cavity 30. The peripheral wall 51 has a radial thickness of about 2 millimetres.

[0207] An air inlet (not visible) and an air outlet 12 are defined by, and extend through, the peripheral wall 51 of the frame 50. The air inlet is positioned opposite the air outlet 12, on the opposite wall of the frame 50. The air inlet and the air outlet 12 each have a rectangular crosssection, a width of 2 millimetres, and a thickness of 0.9 millimetres. An airflow passage extends between the air inlet and the air outlet 12 through the cavity 30.

[0208] The porous aerosol-generating element 40 is rectangular cuboidal in shape, with a length of about 16 millimetres, a width of about 7 millimetres and a thickness of about 3 millimetres. The weight of the porous aerosol-generating element 40 is approximately 120 mg and the density of the porous aerosol-generating element 40 is approximately 350 mg per cubic centimetre. Although the porous aerosol-generating element 40 is shown to fill the cavity 30, in fact the dimensions of the element 40 are slightly smaller than corresponding dimensions of the cavity 30, providing for an air flow path through the cavity when the aerosol-generating element 40 is present.

[0209] The porous aerosol-generating element 40 comprises a solid binder matrix and a cut filler dispersed through the solid binder matrix. An example of a suitable composition of the porous aerosol-generating element 40 is provided below.

[0210] The porous aerosol-generating element has a total porosity of about 0.5 and an open porosity of about 0.45, as determined using the apparatus described above.

[0211] Figure 4 shows an aerosol-generating article 100 according to a second embodiment of the invention. The aerosol-generating article 100 comprises a container 110. The container 110 comprises a first wall 111 and a second wall 112 which together define a substrate compartment 113. An aerosol-generating element 114 is provided in the substrate compartment 113. The substrate compartment 113 has a length of 17 millimetres, a width of 8 millimetres and a depth of 3.5 millimetres.

[0212] The first wall 111 is formed from a non-woven cotton material. The first wall 111 comprises between 85 weight percent and 90 weight percent cellulose, between 7 weight percent and 16 weight percent hemicellulose, and between 1 weight percent and 3 weight percent lignin. The first wall 111 is porous.

[0213] The second wall 112 comprises paper. The second wall 112 has a grammage of about 35 gsm. The second wall is non-porous.

[0214] The second wall 112 may be substantially planar. The second wall 112 has a higher stiffness than the first wall 111. In this way, the first wall 111 may generally form a bag shape which is closed by the second wall 112.

[0215] The first wall 111 and the second wall 112 meet at a contact region 116. The contact region 116 extends around the circumference of the container 110. The contact region 116 has a thickness of 3.5 millimetres. The first wall 111 and the second wall 112 are connected at the contact region 116 by an adhesive to form a sealing region. The adhesive is a polyvinyl alcohol adhesive.

[0216] The first wall 111 and the second wall 112 are thermally stable less than or equal to at least 280 degrees Celsius.

[0217] The aerosol-generating article 100 further comprises a ring element 115 which overlies the sealing region. The ring element 115 is formed from paper having a grammage of 100 gsm. The ring element 115 has a higher stiffness than the first wall 111 and the second wall 112. The ring element 115 overlies the entire sealing region. The ring element 115 is adhered to the first wall 111. In this way, a portion of the first wall 111 is sandwiched between the ring element 115 and the second wall 112. The ring element 115 is adhered to the first wall 111 by a polyvinyl alcohol adhesive. The ring element 115 has a thickness of 3.5 millimetres, corresponding to the thickness of the contact region 116.

[0218] An aerosol-generating element 114 is provided in the substrate compartment 113. The aerosol-generating element 114 is rectangular cuboidal in shape, with a length of about 16 millimetres, a width of about 7 millimetres and a thickness of about 3 millimetres. The weight of the aerosol-generating element 114 is approximately 120 mg and the density of the aerosolgenerating element 114 is approximately 350 mg per cubic centimetre. The aerosol-generating element 114 comprises a solid binder matrix and a cut filler dispersed through the solid binder matrix. An example of a suitable composition of the aerosol-generating element 114 is provided below.

[0219] Example

[0220] Suitable compositions for forming an aerosol-generating element according to the invention are shown in Table 1 below:

[0221]

[0222] Table 1

[0223] All amounts are shown as percentages by weight, on a dry weight basis, based on the total weight of the aerosol-generating element.

[0224] In order to make an aerosol-generating element having a composition according to Samples A to E, a raw tobacco material is first conditioned in a Direct Conditioning Casing Cylinder (DCCC) through the application of glycerin and steam at approximately 60 degrees. The conditioned tobacco material is cut to an average cut width of 1 millimetre and then dried in a Flash Tower Dryer (FTD) at a temperate of 200 degrees Celsius to provide a moisture content of approximately 9 percent oven volatiles (OV). The dried, conditioned tobacco material is added to an After-Cut cylinder where addbacks including tobacco stems and optional clove particles are added to form a cut filler. An aqueous solution of the binder is then applied to the cut filler in the After-Cut cylinder. The binder solution and cut filler are mixed in order to at least partially coat the cut filler in the binder solution. The mixture of the cut filler and binder solution is then compacted by passing the mixture through a series of rollers. The resultant compacted mixture is dried to a moisture content of approximately 10 percent oven volatiles and then cut to form an aerosol-generating element having the desired size and shape.

[0225] Upon heating of the aerosol-generating element in an article as described above with reference to the figures, the aerosol-generating element was found to generate an aerosol providing suitable levels of nicotine and glycerin across the duration of the heating.

[0226] In order to make an aerosol-generating element having a composition according to Sample F, dried chamomile particles are used in place of the raw tobacco material. The remainder of the process as described above may then be followed, including the steps of conditioning the chamomile particles, mixing the chamomile particles with the binder solution, compacting the resultant mixture and drying.

[0227] 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". In this context, therefore, a number A is understood as A ± 10 percent of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

CLAIMS1. A porous aerosol-generating element for generating an inhalable aerosol upon heating, the porous aerosol-generating element comprising: a solid binder matrix comprising at least one binder, wherein the porous aerosolgenerating element comprises at least 1 percent by weight of the binder on a dry weight basis; and cut filler dispersed within the solid binder matrix, the cut filler comprising shredded plant material impregnated with an aerosol former, wherein the shredded plant material has an average cut width of at least 0.75 millimetres, wherein the porous aerosol-generating element comprises at least 10 percent by weight of the aerosol former on a dry weight basis; and wherein the porous aerosol-generating element has an average density of less than or equal to 420 mg per cubic centimetre.

2. A porous aerosol-generating element according to claim 1 , wherein the shredded plant material in the cut filler comprises shredded tobacco.

3. A porous aerosol-generating element according to claim 1 or 2, comprising at least 15 percent by weight of aerosol former.

4. A porous aerosol-generating element according to any preceding claim, comprising less than or equal to 30 percent by weight of the binder, on a dry weight basis.

5. A porous aerosol-generating element according to any preceding claim, wherein the weight ratio of the cut filler to the binder is at least 3, on a dry weight basis.

6. A porous aerosol-generating element according to any preceding claim, wherein the binder comprises a polyvinyl alcohol, nanocellulose, or a combination thereof.

7. A porous aerosol-generating element according to any preceding claim, having a moisture content of less than or equal to 20 percent oven volatiles.

8. A porous aerosol-generating element according to any preceding claim, having a total porosity of at least 0.3.

9. A porous aerosol-generating element according to any preceding claim, wherein the aerosol-generating element has a length, a width and a thickness, the length and the width being at least twice the thickness of the aerosol-generating element.

10. A porous aerosol-generating element according to claim 9, wherein the average thickness of the aerosol-generating element is at least 2 millimetres.

11. A porous aerosol-generating element according to claim 9 or 10, wherein the average thickness of the porous aerosol-generating element is at least 3 times the average cut width of the cut filler.

12. An aerosol-generating article comprising an aerosol-generating substrate, the aerosolgenerating substrate comprising one or more aerosol-generating elements according to any preceding claim.

13. An aerosol-generating article according to claim 12, wherein the aerosol-generating article has an article length, an article width and an article thickness, the article length and the article width being at least twice the article thickness.

14. A method of producing a porous aerosol-generating element according to any preceding claim, the method comprising the steps of: providing a plant material; conditioning the plant material, wherein the conditioning includes applying an aerosol former to the plant material, wherein the amount of aerosol former applied to the plant material corresponds to at least 15 percent by weight on a dry weight basis, based on the weight of the plant material; cutting the plant material to a provide a shredded plant material with an average cut width of at least 0.75mm; drying the conditioned plant material to provide a cut filler having a defined moisture level; adding a binder solution comprising one or more binders to the cut filler and mixing the binder solution and the cut filler to at least partially coat the cut filler with the binder solution; compacting the mixture of binder solution and cut filler; drying the compacted mixture to form a solid substrate comprising a solid binder matrix having the cut filler dispersed through it; and forming a discrete porous aerosol-generating element from the solid substrate.

15. A method according to claim 14, wherein the binder solution is applied to the cut filler in an after-cut cylinder.

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