Aerosol-generating article comprising substrate with nicotine

Abstract

An aerosol-generating article (10)(110)(210)(410) for use with an aerosol-generating device to generate an inhalable aerosol comprises: a first planar external surface (21); a second planar external surface (22); a cavity (30); a frame (50) positioned between the first planar external surface (21) and the second planar external surface (22), the frame (50) at least partially defining the cavity (30); one or more sheets of an aerosol-generating substrate (140); and an air inlet (11) and an air outlet (12), and an airflow passage extending between the air inlet (11) and the air outlet (12) through the cavity (30). The aerosol-generating substrate (140) comprises exogenous nicotine and one or more aerosol formers. The total aerosol former content of the aerosol-generating substrate is at least 40 percent by weight.

Description

[0001] AEROSOL-GENERATING ARTICLE COMPRISING SUBSTRATE WITH NICOTINE

[0002] The present disclosure relates to an aerosol-generating article. The present disclosure also relates to an aerosol-generating system comprising the aerosol-generating device and the aerosolgenerating article.

[0003] A typical aerosol-generating system comprises an aerosol-generating device and an aerosolgenerating article comprising an aerosol-generating substrate. In use, the aerosol-generating device is arranged to heat a heating element that is positioned near, or in contact with, the aerosol-generating substrate which causes the aerosol-generating substrate to heat up and release volatile compounds. These volatile compounds are then entrained in air that is drawn through the aerosol-generating article. As the volatile compounds cool, they condense to form an aerosol that can be inhaled by a consumer.

[0004] A typical aerosol-generating article may appear similar and have similar dimensions to a conventional cigarette. For example, such an aerosol-generating article may be substantially cylindrical and comprise an aerosol-generating substrate in addition to other components such as mouthpiece filter element and a cooling element, which are arranged in the form of a rod and wrapped in a cigarette paper.

[0005] However, a significant portion of the aerosol-generating substrate in these cylindrical aerosolgenerating articles may not be sufficiently heated to form an aerosol during use. This is undesirable since the insufficiently heated portion of the aerosol-generating substrate contributes to the cost of manufacture and transport of the aerosol-generating article but does not contribute to the aerosol delivered to the consumer. Moreover, the components of these cylindrical aerosol-generating articles normally need to have the same or very similar outer diameters so that they can be brought together, accurately positioned in axial alignment and wrapped in a cigarette paper. This can lead to increased cost and complexity of manufacture.

[0006] It is an objective of the present disclosure to provide an aerosol-generating article in which a greater portion of the aerosol-generating substrate is sufficiently heated to form an aerosol during use. It is also an objective of the present disclosure to provide an aerosol-generating article which can provide an optimised delivery of aerosol to the consumer upon heating. It is also an objective of the present disclosure to provide an aerosol-generating article that can be manufactured relatively efficiently and cheaply.

[0007] According to the present disclosure, there is provided an aerosol-generating article. The aerosol-generating article is for use with an aerosol-generating device to generate an inhalable aerosol. The aerosol-generating article may comprise a first planar external surface. The aerosolgenerating article may comprise a second planar external surface. The aerosol-generating article may comprise a cavity. The aerosol-generating article may comprise a frame positioned between the first planar external surface and the second planar external surface. The frame may at least partially define the cavity. The aerosol-generating article may comprise an aerosol-generating substrate. The aerosol-generating substrate may comprise exogenous nicotine. The aerosol-generating substrate may comprise one or more aerosol formers. The total aerosol former content of the aerosol-generating substrate may be at least 40 percent by weight on a dry weight basis. The aerosol-generating article may comprises an air inlet and an air outlet. The aerosol-generating article may comprise an airflow passage extending between the air inlet and the air outlet through the cavity.

[0008] According to the present invention there is provided an aerosol-generating article for use with an aerosol-generating device to generate an inhalable aerosol, 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; an aerosol-generating substrate comprising exogenous nicotine and one or more aerosol formers, wherein the total aerosol former content of the aerosol-forming substrate is at least 40 percent by weight on a dry weight basis; and an air inlet and an air outlet, and an airflow passage extending between the air inlet and the air outlet through the cavity.

[0009] Preferably, the article has an article length, an article width and an article thickness, the article length and the article width being at least two times the article thickness.

[0010] According to the present disclosure there is further provided an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating article according to the present disclosure, as defined above. The aerosol-generating system may comprise an aerosol-generating device for use with the aerosol-generating article to generate an inhalable article. The aerosolgenerating device may comprise a heater for heating the aerosol-generating substrate of the aerosolgenerating article. The heater may be configured to heat the aerosol-generating substrate to a maximum temperature of 210 degrees Celsius.

[0011] According to the present invention there is provided an aerosol-generating system comprising: an aerosol-generating article according to the present invention as defined above and an aerosolgenerating device for use with the aerosol-generating article to generate an inhalable aerosol, wherein the aerosol-generating device comprises a heater for heating the aerosol-generating substrate of the aerosol-generating article and wherein the heater is configured to heat the aerosol-generating substrate to a maximum temperature of 210 degrees Celsius.

[0012] According to the present disclosure, the aerosol-generating article is a planar aerosolgenerating article having a length extending in an x direction (corresponding to the article length), a width extending in a y direction (corresponding to the article width), and a thickness extending in a z direction (corresponding to the article thickness).

[0013] For the purpose of the present disclosure, the “thickness” of the aerosol-generating article may also be referred to as the “height” of the aerosol-generating article.

[0014] Any reference to the length, width, height or thickness of the aerosol-generating article should be considered to relate to the average length, width, heightorthickness, respectively, unless otherwise indicated.

[0015] Preferably, the thickness of the aerosol-generating article is less than or equal to 50 percent of both of the length and width of the aerosol-generating article. Aerosol-generating articles according to the present disclosure may preferably be substantially flat articles or substantially planar articles. Advantageously, a larger base area may provide greater surface area for heating by a planar heater of an aerosol-generating device. Advantageously, a smaller height may allow a smaller temperature gradient or difference across the height of the aerosolgenerating article during heating. For example, where the base of the aerosol-generating article is in contact with, and heated by, a planar heater, there may be a smaller temperature difference between the base and an upper surface opposing the base if the spacing, or height, between the base and the upper surface is smaller. Advantageously, this may allow heating of a greater proportion of the aerosolforming substrate of the aerosol-generating article to a temperature at which an aerosol is released, whilst minimising the risk of burning the hottest portion of the substrate closest to the heater. Alternatively, or in addition, this may reduce a time required to heat the aerosol-forming substrate sufficiently to release an aerosol.

[0016] The aerosol-generating articles of the present invention provide a planar structure including a frame.

[0017] Advantageously, the frame may allow the aerosol-generating article to be relatively thin whilst maintaining structural rigidity.

[0018] Advantageously, the first planar external surface and the second planar external surface allow for good contact with an external heater, particularly an external heater, of an aerosol-generating device, thereby providing optimum heating of the aerosol-generating substrate.

[0019] Advantageously, aerosol-generating articles of the present disclosure may be heated along substantially their entire length and width, thereby allowing the entire aerosol-generating substrate to be sufficiently heated to generate an aerosol.

[0020] Advantageously, aerosol-generating articles of the present disclosure may be manufactured by layering sheet materials which can be achieved through a continuous manufacturing process, thereby resulting in an aerosol-generating article that is relatively easy and cheap to manufacture.

[0021] The aerosol-generating articles of the present invention comprise an aerosol-generating substrate which includes exogenous nicotine and a relatively high level of aerosol former.

[0022] The use of such aerosol-generating substrates is particularly advantageous for planar or flat aerosol-generating articles, such as those of the present invention. Due to the reduced time required to heat the aerosol-generating substrate of a planar aerosol-generating article in order to generate an aerosol, as described above, active agents such as nicotine, as well as other relatively volatile components such as flavourants, may be released from the aerosol-generating substrate relatively quickly upon heating of the aerosol-generating substrate. These active agents may therefore be present in relatively high levels during the early puffs. The provision of an aerosol-generating substrate having a relatively high aerosol former content has been advantageously found to provide a quicker and more consistent delivery of aerosol former into the aerosol, which ensures that there is an optimal balance in the aerosol between the aerosol former and the active agent. As described above, this balance may be particularly important during the early puffs but the relatively high level of aerosol former in the aerosol-generating substrate also enables the balance to be retained throughout heating. Due to the more efficient heating of the aerosol-generating substrate in planar or flat aerosolgenerating articles, it is advantageously possible for such articles to be heated at a lower temperature than conventional aerosol-generating articles having a cylindrical rod of aerosol-forming substrate. When lower temperatures are used for heating of the aerosol-forming substrate, the inclusion of a relatively high level of aerosol former, as in the present invention, helps to ensure that there is still an optimal delivery of aerosol to the consumer, throughout the heating cycle.

[0023] The use of the aerosol-generating substrates as described herein has also been found to provide a highly stable way to incorporate nicotine into aerosol-generating articles. The inclusion of exogenous nicotine within the aerosol-generating substrate provides a high degree of control over the amount of nicotine delivered into the aerosol and also facilitates the delivery of nicotine at the lower temperatures which may be used for planar or flat consumables.

[0024] The use of an aerosol-generating substrate having a relatively high level of aerosol former has been found to be particularly effective in aerosol-generating articles such as those described below, which do not incorporate filtration material. In the absence of filtration material, there is minimal removal of the aerosol former from the aerosol as it passes through the aerosol-generating article, so that an optimised volume of aerosol can be delivered to the consumer, with a desirable balance between the aerosol former and active agent.

[0025] In some embodiments of the present invention, the aerosol-generating substrates can advantageously be formed with a low (or zero) level of tobacco particles, which means that the levels of undesirable tobacco compounds in the aerosol are reduced whilst still maintaining an acceptable delivery of nicotine or other active agent.

[0026] The aerosol-generating substrate of aerosol-generating articles according to the present invention comprises one or more aerosol formers. Suitable aerosol formers for inclusion in the homogenised plant material are known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, propylene glycol, 1 ,3-butanediol and glycerol; 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. Preferably, the aerosol former comprises one or more of glycerol and propylene glycol. The aerosol former may consist of glycerol or propylene glycol or of a combination of glycerol and propylene glycol.

[0027] According to the invention, the aerosol-generating substrate has an aerosol former content of at least 40 percent by weight on a dry weight basis. Preferably, the aerosol-generating substrate has an aerosol former content of at least 45 percent by weight, on a dry weight basis. More preferably, the aerosol-generating substrate has an aerosol former content of at least 50 percent by weight.

[0028] The aerosol-generating substrate preferably has an aerosol former content of less than or equal to 70 percent by weight on a dry weight basis. More preferably, the aerosol-generating substrate has an aerosol former content of less than or equal to 65 percent by weight, more preferably less than or equal to 60 percent by weight, on a dry weight basis. For example, the aerosol former content of the aerosol-generating substrate is preferably between 40 percent and 70 percent by weight, or between 45 percent and 70 percent by weight, or between 50 percent and 70 percent by weight, on a dry weight basis.

[0029] For example, the aerosol former content of the aerosol-generating substrate is preferably between 40 percent and 65 percent by weight, or between 45 percent and 65 percent by weight, or between 50 percent and 65 percent by weight, on a dry weight basis.

[0030] For example, the aerosol former content of the aerosol-generating substrate is preferably between 40 percent and 60 percent by weight, or between 45 percent and 60 percent by weight, or between 50 percent and 60 percent by weight, on a dry weight basis.

[0031] Preferably, the aerosol-generating substrate comprises glycerol as an aerosol former. For example, the aerosol-generating substrate may comprise between 40 percent and 65 percent by weight of glycerol, or between 45 percent and 60 percent by weight of glycerol, or between 50 percent and 60 percent by weight of glycerol, or between 50 percent and 55 percent by weight of glycerol, on a dry weight basis.

[0032] According to the invention, the aerosol-generating substrate further comprises exogenous nicotine.

[0033] As used herein with reference to the invention, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt. In embodiments in which the aerosol-generating substrate comprises a nicotine base or a nicotine salt, the amounts of nicotine recited herein are the amount of free base nicotine or amount of protonated nicotine, respectively.

[0034] As used herein with reference to the invention, the term “exogenous” refers to any nicotine incorporated into the aerosol-generating substrate which is provided extrinsically from the tobacco material present in the aerosol-generating substrate. The exogenous nicotine is therefore a separate and distinct source of nicotine to the nicotine provided intrinsically within any tobacco material that is present.

[0035] The exogenous nicotine may be in the form of natural nicotine, or synthetic nicotine, or a combination of natural nicotine and synthetic nicotine.

[0036] The aerosol-generating substrate may have a total exogenous nicotine content of at least 0.5 percent by weight, at least 1 percent by weight, at least 1 .5 percent by weight, or at least 2 percent by weight, on a dry weight basis.

[0037] The aerosol-generating substrate may have a total exogenous nicotine content of less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight, on a dry weight basis.

[0038] The aerosol-generating substrate may have a total exogenous nicotine content of between 0.5 percent by weight and 10 percent by weight, between 0.5 percent by weight and 8 percent by weight, between 0.5 percent by weight and 6 percent by weight, or between 0.5 percent by weight and 4 percent by weight, on a dry weight basis.

[0039] The aerosol-generating substrate may have a total exogenous nicotine content of between 1 percent by weight and 10 percent by weight, between 1 percent by weight and 8 percent by weight, between 1 percent by weight and 6 percent by weight, or between 1 percent by weight and 4 percent by weight, on a dry weight basis.

[0040] The aerosol-generating substrate may have a total exogenous nicotine content of between 1.5 percent by weight and 10 percent by weight, between 1.5 percent by weight and 8 percent by weight, between 1 .5 percent by weight and 6 percent by weight, or between 1 .5 percent by weight and 4 percent by weight.

[0041] The aerosol-generating substrate may have a total exogenous nicotine content of between 2 percent by weight and 10 percent by weight, between 2 percent by weight and 8 percent by weight, between 2 percent by weight and 6 percent by weight, or between 2 percent by weight and 4 percent by weight.

[0042] Alternatively or in addition to the active agent, the aerosol-generating substrate may further comprise one or more flavourants. The inclusion of one or more flavourants may be advantageous in order to provide a desired level of flavourant, in view of the potentially relatively low sensorial impact of the non-tobacco botanical particles used in the aerosol-generating substrate.

[0043] 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.

[0044] The aerosol-generating substrate may have a flavourant content of at least 0.5 percent by weight, preferably at least 1 percent by weight, more preferably at least 2 percent by weight, on a dry weight basis.

[0045] The aerosol-generating substrate may have a flavourant content of less than or equal to 10 percent by weight, preferably less than or equal to 8 percent by weight, more preferably less than or equal to 5 percent by weight, on a dry weight basis.

[0046] For example, the aerosol-generating substrate may have a flavourant content of between 0.5 percent and 10 percent by weight, or between 1 percent and 8 percent by weight, or between 2 percent and 5 percent by weight, on a dry weight basis.

[0047] The aerosol-generating substrate of aerosol-generating articles according to the invention preferably further comprises one or more cellulose based agents.

[0048] As used herein with reference to the invention, the term “cellulose based agent” is used to describe a cellulosic substance. Examples of cellulose based agents include cellulose based filmforming agents, cellulose based strengthening agents and cellulose based binding agents.

[0049] The aerosol-generating substrate may comprise a plurality of cellulose based agents. That is, the aerosol-generating substrate may comprise two or more cellulose based agents. For example, the aerosol-generating substrate may comprise two cellulose based agents, three cellulose based agents, four cellulose based agents, or five cellulose based agents.

[0050] Preferably, the aerosol-generating substrate has a total cellulose based agent content of at least 35 percent by weight.

[0051] As used herein with reference to the invention, the term “total cellulose based agent” is used to describe the combined content of all cellulose based agents in the aerosol-generating substrate. For example, where the aerosol-generating substrate comprises a plurality of cellulose based agents consisting of a cellulose based film-forming agent, a cellulose based strengthening agent, and a cellulose based binding agent, the term “total cellulose based agent content” describes the combined cellulose based film-forming agent content, cellulose based strengthening agent content, and cellulose based binding agent content of the aerosol-generating substrate.

[0052] The aerosol-generating substrate may have a total cellulose based agent content of at least 36 percent by weight, at least 38 percent by weight, or at least 40 percent by weight, on a dry weight basis.

[0053] The aerosol-generating substrate may have a total cellulose based agent content of less than or equal to 52 percent by weight, less than or equal to 50 percent by weight, less than or equal to 48 percent by weight, less than or equal to 46 percent by weight, or less than or equal to 44 percent by weight, on a dry weight basis.

[0054] The aerosol-generating substrate may comprise one or more cellulose based film-forming agents.

[0055] As used herein with reference to the invention, the term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film.

[0056] Advantageously, the aerosol-generating substrate may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose (CMC), ethylcellulose (EC), hydroxyethyl cellulose (HEC), hydroxyethyl methylcellulose (HEMC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), and methylcellulose (MC).

[0057] More advantageously, the aerosol-generating substrate may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose (CMC), ethylcellulose (EC), methylcellulose (MC), and hydroxypropyl methylcellulose (HPMC).

[0058] Most advantageously, the aerosol-generating substrate comprises one or more cellulose based film-forming agents selected from carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC).

[0059] Preferably, the aerosol-generating substrate comprises carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC).

[0060] The one or more cellulose based film-forming agents may act as a binding agent for the aerosol-generating substrate.

[0061] The aerosol-generating substrate may have a total cellulose based film-forming agent content of at least 15 percent by weight, at least 20 percent by weight, or at least 25 percent by weight, on a dry weight basis.

[0062] As used herein with reference to the invention, the term “total cellulose based film-forming agent content” is used to describe the combined content of all cellulose based film-forming agents in the aerosol-generating substrate. The aerosol-generating substrate may have a total cellulose based film-forming agent content of less than or equal to 40 percent by weight, less than or equal to 35 percent by weight, or less than or equal to 30 percent by weight, on a dry weight basis.

[0063] The aerosol-generating substrate may comprise sodium carboxymethyl cellulose.

[0064] The aerosol-generating substrate may have a carboxymethyl cellulose content of at least 2 percent by weight, at least 3 percent by weight, at least 4 percent by weight, or at least 5 percent by weight, on a dry weight basis

[0065] The aerosol-generating substrate may have a carboxymethyl cellulose content of less than or equal to 12 percent by weight, less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, or less than or equal to 6 percent by weight, on a dry weight basis.

[0066] The aerosol-generating substrate may comprise one or more cellulose based strengthening agents.

[0067] Inclusion of one or more cellulose based strengthening agents in the aerosol-generating substrate may advantageously increase the tensile strength of the aerosol-generating substrate

[0068] Advantageously, the aerosol-generating substrate may comprise one or more cellulose based strengthening agents selected from cellulose fibres, cellulose powder, and microcrystalline cellulose (MCC).

[0069] The aerosol-generating substrate may have a total cellulose based strengthening agent content of at least 5 percent by weight, at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0070] As used herein with reference to the invention, the term “total cellulose based strengthening agent content” is used to describe the combined content of all cellulose based strengthening agents in the aerosol-generating substrate.

[0071] The aerosol-generating substrate may have a total cellulose based strengthening agent content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight, on a dry weight basis.

[0072] Preferably, the aerosol-generating substrate comprises cellulose fibres. Cellulose fibres may be particularly effective at increasing the tensile strength of the aerosol-generating substrate

[0073] The aerosol-generating substrate may comprise cellulose fibres having a length of at least 0.2 millimetres, at least 0.5 millimetres, at least 0.7 millimetres, or at least 0.9 millimetres.

[0074] The aerosol-generating substrate may comprise cellulose fibres having a length of less than or equal to 2 millimetres, less than or equal to 1 .8 millimetres, less than or equal to 1 .6 millimetres, or less than or equal to 1 .4 millimetres.

[0075] The aerosol-generating substrate may have a cellulose fibre content of at least 2 percent by weight, at least 5 percent by weight, at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0076] The aerosol-generating substrate may have a cellulose fibre content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight, on a dry weight basis. The aerosol-generating substrate may comprise microcrystalline cellulose having a D50 size of at least 5 micrometres, at least 10 micrometres, or at least 15 micrometres.

[0077] As used herein with reference to the invention, the term “D50 size” describes the median particle size of a particulate material. The D50 size is the particle size which splits the distribution in half, where half of the particles are larger than the D50 size and half of the particles are smaller than the D50 size. The particle size distribution may be determined by laser diffraction, as described above.

[0078] The aerosol-generating substrate may comprise microcrystalline cellulose having a D50 size of less than or equal to 100 micrometres, less than or equal to 90 micrometres, or less than or equal to 80 micrometres.

[0079] The aerosol-generating substrate may have a microcrystalline cellulose content of at least 2 percent by weight, at least 5 percent by weight, at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0080] The aerosol-generating substrate may have a microcrystalline cellulose content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight, on a dry weight basis.

[0081] The aerosol-generating substrate may comprise cellulose powder having a D50 size of at least 25 micrometres, at least 30 micrometres, or at least 35 micrometres.

[0082] The aerosol-generating substrate may comprise cellulose powder having a D50 size of less than or equal to 250 micrometres, less than or equal to 225 micrometres, or less than or equal to 200 micrometres.

[0083] The aerosol-generating substrate may have a cellulose powder content of at least 2 percent by weight, at least 5 percent by weight, at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0084] The aerosol-generating substrate may have a cellulose powder content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight, on a dry weight basis.

[0085] The aerosol-generating substrate may comprise one or more carboxylic acids.

[0086] The aerosol-generating substrate may comprise a plurality of carboxylic acids. That is, the aerosol-generating substrate may comprise two or more carboxylic acids. For example, the aerosolgenerating substrate may comprise two carboxylic acids, three carboxylic acids, four carboxylic acids, or five carboxylic acids.

[0087] The aerosol-generating substrate may comprise one or more diprotic carboxylic acids. For example, the aerosol-generating substrate may comprise one or more diprotic carboxylic acids selected from fumaric acid, maleic acid, malic acid, adipic acid and succinic acid.

[0088] The aerosol-generating substrate may comprise one or more triprotic carboxylic acids. For example, the slid aerosol-generating substrate may compise citric acid.

[0089] The aerosol-generating substrate may comprise one or more carboxylic acids selected from lactic acid, levulinic acid, acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid. The aerosol-generating substrate may comprise one or more carboxylic acids selected from acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid.

[0090] Preferably, the aerosol-generating substrate comprises one or more carboxylic acids selected from fumaric acid, maleic acid, and malic acid.

[0091] More preferably, the aerosol-generating substrate comprises fumaric acid.

[0092] The aerosol-generating substrate may further comprise one or more carboxylic acids selected from lactic acid and levulinic acid. For example, the aerosol-generating substrate may comprise a combination of fumaric acid and lactic acid, or fumaric acid and levulinic acid.

[0093] The aerosol-generating substrate has a total carboxylic acid content of at least 0.5 percent by weight.

[0094] As used herein with reference to the invention, the term “total carboxylic acid content” is used to describe the combined content of all carboxylic acids in the aerosol-generating substrate. For example, where the aerosol-generating substrate comprises a plurality of carboxylic acids consisting of benzoic acid and fumaric acid, the term “total carboxylic acid content” describes the combined benzoic acid content and fumaric acid content of the aerosol-generating substrate.

[0095] The aerosol-generating substrate may have a total carboxylic acid content of at least 1 percent by weight, at least 1 .5 percent by weight, or at least 2 percent by weight.

[0096] The aerosol-generating substrate may have a total carboxylic acid content of less than or equal to 8 percent by weight, less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight.

[0097] The aerosol-generating substrate may comprise one or more non-cellulose based thickening agents.

[0098] As used herein with reference to the invention, the term “non-cellulose based thickening agent” is used to describe a non-cellulosic substance that, when added to an aqueous or non-aqueous liquid composition, increases the viscosity of the liquid composition without substantially modifying its other properties. The one or more non-cellulose based thickening agents may increase stability, and improve suspension of components in the liquid composition. Athickening agent may also be referred to as a “thickener” or a “rheology modifier” or “viscosifying agent”.

[0099] The aerosol-generating substrate may comprise one or more non-cellulose based thickening agents selected from alginates, gellan gum, guar gum, gum arabic, locust bean gum, pectins, starches, and xanthan gum.

[0100] The aerosol-generating substrate may have a total non-cellulose based thickening agent content of at least 1 percent by weight, at least 2 percent by weight, or at least 3 percent by weight, on a dry weight basis.

[0101] As used herein with reference to the invention, the term “total non-cellulose based thickening agent content” is used to describe the combined content of all non-cellulose based thickening agents in the aerosol-generating substrate. The aerosol-generating substrate may have a total non-cellulose based thickening agent content of less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, or less than or equal to 6 percent by weight.

[0102] The aerosol-generating substrate may be a substantially tobacco-free aerosol-generating substrate.

[0103] As used herein with reference to the invention, the term “substantially tobacco-free aerosolgenerating substrate” is used to describe a aerosol-generating substrate having a tobacco content of less than 1 percent by weight. For example, the aerosol-generating substrate may have a tobacco content of less than 0.75 percent by weight, less than 0.5 percent by weight, or less than 0.25 percent by weight.

[0104] The aerosol-generating substrate can be provided in any suitable form. For example, the aerosol-generating substrate may be in the form of one or more sheets. As used herein with reference to the invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.

[0105] Alternatively or in addition, the aerosol-generating substrate may be in the form of a plurality of strands, strips or shreds. As used herein, the term “strand” describes an elongate element of material having a length that is substantially greater than the width and thickness thereof. The term “strand” should be considered to encompass strips, shreds and any other aerosol-generating substrate having a similar form. The strands of aerosol-generating substrate may be formed from a sheet of aerosol-generating substrate, for example by cutting or shredding, or by other methods.

[0106] Preferably, the aerosol-generating substrate is in the form of one or more sheets.

[0107] Each of the one or more sheets of aerosol-generating substrate may have a grammage of at least 130 grams per square metre, or at least 135 grams per square metre, or at least 140 grams per square metre.

[0108] Each of the one or more sheets of aerosol-generating substrate may have a grammage of less than or equal to 160 grams per square metre, or less than or equal to 155 grams per square metre, or less than or equal to 150 grams per square metre.

[0109] As used herein, the term “grammage" is equivalent to the “basis weight” of the sheet of aerosolgenerating substrate and is defined as equal to the mass per unit area of the sheet. The grammage may be determined in accordance with ISO Standard 536:2012.

[0110] Unless stated otherwise, measurements performed on a sheet of aerosol-generating substrate described herein are performed at 23 degrees Celsius and at a relative humidity of 50 percent.

[0111] Each of the one or more sheets of aerosol-generating substrate may have an average thickness of at least 175 microns, or at least 180 microns, or at least 185 microns, or at least 190 microns.

[0112] Each of the one or more sheets of aerosol-generating substrate may have an average thickness of less than or equal to 225 microns, or less than or equal to 220 microns, or less than or equal to 215 microns, or less than or equal to 210 microns. As used herein, the term “thickness” is used to describe the smallest dimension of the sheet of aerosol-generating substrate. The thickness is measured perpendicular to the length and width of the sheet. The thickness may be determined in accordance with ISO Standard 534:2012.

[0113] Each of the one or more sheets of aerosol-generating substrate may have a density of at least 0.5 grams per cubic centimetre, or at least 0.55 grams per cubic centimetre, or at least 0.6 grams per cubic centimetre.

[0114] Each of the one or more sheets of aerosol-generating substrate may have a density of less than or equal to 1 gram per cubic centimetre, or less than or equal to 0.9 grams per cubic centimetre, or less than 0.8 grams per cubic centimetre.

[0115] Fora sheet of aerosol-generating substrate as described herein, the density may be calculated by dividing the grammage of the sheet by the thickness of the sheet. The grammage and thickness of the sheet may be measured as set out above.

[0116] The one or more sheets of aerosol-generating substrate may be gathered.

[0117] The one or more sheets of aerosol-generating substrate may be textured. This may facilitate gathering of the aerosol-generating substrate to form an aerosol-generating rod for inclusion in an aerosol-generating article according to the first aspect of the invention.

[0118] As used herein with reference to the invention, the term “textured” is used to describe a sheet of aerosol-generating substrate that has been crimped, embossed, debossed, perforated or otherwise deformed. Textured sheets of aerosol-generating substrate may comprise a plurality of spaced-apart indentations, protrusions, perforations or a combination thereof.

[0119] The one or more sheets of the aerosol-generating substrate may be crimped.

[0120] As used herein with reference to the invention, the term “crimped” is intended to be synonymous with the term “creped” and is used to describe a sheet of a aerosol-generating substrate having a plurality of substantially parallel ridges or corrugations.

[0121] Each of the sheets may have a tensile strength at peak in a cross direction of at least 150 Newtons per metre (N / m), or at least 160 N / m, or at least 170 N / m, or at least 180 N / m. The tensile strength at peak in a cross direction may be up to 400 N / m, or up to 300 N / m.

[0122] Each of the sheets may have a tensile strength at peak in a machine direction of at least 450 Newtons per metre (N / m), or at least 475 N / m, or at least 500 N / m, or at least 525 N / m. The tensile strength at peak in a machine direction may be up to 700 N / m, or up to 600 N / m.

[0123] The term “tensile strength” is used throughout the specification to indicate a measure of the force required to stretch a sheet of aerosol-generating substrate until it breaks. More specifically, the tensile strength is the maximum tensile force per unit width that the sheet material will withstand before breaking and is measured in the machine direction or cross direction of the sheet material. It is expressed in units of Newtons per meter of material (N / m). Tests for measuring the tensile strength of a sheet material are well known. A suitable test is described in the 2008 publication of the International Standard ISO 1924-2 entitled “Paper and Board - Determination of Tensile Properties - Part 2: Constant Rate of Elongation Method”.

[0124] The aerosol-generating substrate may be a aerosol-generating film. As used herein with reference to the invention, the term “film” is used to describe a aerosolgenerating substrate having a thickness that is substantially less than the width or length thereof.

[0125] The aerosol-generating substrate may be formed by any suitable method. For example, the aerosol-generating substrate may be formed by batch casting, continuous casting or extrusion.

[0126] Preferably, the aerosol-generating substrate is formed by a casting method. In such a method, a slurry is formed of the solid components of the aerosol-generating substrate in water. The slurry is then cast on a support surface and dried to solidify the slurry into a sheet of aerosol-generating substrate. The cast slurry may be heated to facilitate drying.

[0127] The aerosol-generating substrate may be self-supporting.

[0128] The aerosol-generating substrate may be disposed on a support or the aerosol-generating substrate may be sandwiched between other materials.

[0129] The aerosol-generating substrate as described herein may be provided within the cavity. Alternatively, the cavity may be empty and the aerosol-generating substrate is provided outside of the cavity.

[0130] Alternatively or in addition, one or more sheets or layers of the aerosol-generating substrate as described herein may be positioned between the frame and the first external surface. One more sheets of aerosol-generating substrate as described herein may be positioned between the frame and the second external surface. The aerosol-generating substrate may be in physical contact with, and may be bonded to, the frame.

[0131] One or more sheets or layers of aerosol-generating substrate as described herein may be positioned between the frame and an outer wrapper. The outer wrapper is discussed in more detail below. The aerosol-generating substrate may in physical contact with, and may be bonded to, both the frame and the outer wrapper.

[0132] One or more sheets or layers of aerosol-generating substrate as described herein may be positioned between the frame and a first planar external layer. One or more sheets of homogenised plant material as described herein may be positioned between the frame and a second planar external layer. The first planar external layer and the second planar external layer are discussed in more detail below. The aerosol-generating substrate may in physical contact with, and may be bonded to, both the frame and the first planar external layer. The aerosol-generating substrate may in physical contact with, and may be bonded to, both the frame and the second planar external layer.

[0133] The aerosol-generating article may have a length extending in an x-direction. The aerosolgenerating article may have a width extending in a y-direction. The aerosol-generating article may have a thickness extending in a z-direction.

[0134] The aerosol-generating article may be a substantially flat aerosol-generating article or a substantially planar aerosol-generating article. In particular, a thickness of the aerosol-generating article may less than 50 percent of both a length and a width of the aerosol-generating article. Advantageously, a smaller thickness may provide a small temperature gradient or difference across the thickness of the aerosol-generating substrate during heating. The aerosol-generating article may have a quadrilaterally-faced hexahedron shape. The aerosol-generating article may have a rectangular prism shape. The aerosol-generating article may have a cuboid shape. The aerosol-generating article may have a cylindrical shape. The aerosolgenerating article may have a right-angled cylinder shape.

[0135] The aerosol-generating article may have a laminated structure, for example the aerosolgenerating article may comprise or be formed from at least two layers. In particular, the aerosolgenerating article may comprise at least two of: a first external layer, a second external layer, a frame, a first frame layer, a second frame layer, a third frame layer, a first aerosol-generating substrate layer, and a second aerosol-generating substrate layer as discussed in more detail below.

[0136] Substantially the entirety of the aerosol-generating article, excluding the one or more aerosolgenerating substrates (if present) and (if present) adhesive, may be paper or cardboard.

[0137] The aerosol-generating article may have a cellulose acetate content of less than 5 percent. The aerosol-generating article may have a cellulose acetate content of less than 3 percent. The aerosol-generating article may have a cellulose acetate content of less than 1 percent.

[0138] The frame may be a planar frame.

[0139] The frame may define a frame aperture extending through the thickness of the frame. The frame aperture may define or form the airflow passage of the aerosol-generating article. The frame aperture may define or form the cavity of the aerosol-generating article. For example, the frame may have a hollow cuboid shape or a square hollow tube shape. As a further example, the frame may have a cross-section that is annular in shape, preferably the cross-section in an x / y plane is annular in shape.

[0140] The frame may comprise a frame outer surface. The frame outer surface may extend in a transverse direction, for example between the first planar external surface and the second planar external surface. The frame outer surface may at least partially define or form one or more external surfaces of the aerosol-generating article. For example, the frame outer surface may at least partially define or form one or more external walls of the aerosol-generating article. The frame outer surface may circumscribe or encircle the frame aperture. The frame outer surface may circumscribe or encircle the cavity.

[0141] The frame may comprise a frame inner surface. The frame inner surface may extend in a transverse direction, for example between the first planar external surface and the second planar external surface. The frame inner surface may define or form a frame aperture outer wall. The frame inner surface may define or form a cavity outer wall. The frame inner surface may circumscribe or encircle the frame aperture extending through the thickness of the frame. The frame inner surface may circumscribe or encircle the cavity.

[0142] The frame outer surface may circumscribe or encircle the frame inner surface. The frame inner surface and the frame outer surface may be concentric with one another.

[0143] The aerosol-generating article may comprise one or more external walls extending between the first planar external surface and the second planar external surface. The one or more external walls may collectively define an entire transverse external area of the aerosol-generating article. The frame may at least partially define each of the one or more external walls. The one or more external walls may circumscribe or encircle the cavity. The frame may define at least 60 percent, at least 70 percent, at least 80 percent, or at least 90 percent of the entire transverse external area of the aerosolgenerating article.

[0144] The frame may comprise a peripheral wall. The peripheral wall may circumscribe or encircle at least a portion of the frame aperture extending through the thickness of the frame. The peripheral wall may circumscribe or encircle at least a portion of the cavity. The peripheral wall may circumscribe or encircle the frame aperture extending through the thickness of the frame. The peripheral wall may circumscribe or encircle the cavity.

[0145] The peripheral wall may be defined or formed by the frame outer surface and the frame inner surface. The peripheral wall may at least partially define or form one or more external surfaces or walls of the aerosol-generating article. The peripheral wall may define or form a frame aperture outer wall. The peripheral wall may define or form a cavity outer wall.

[0146] The peripheral wall may have a radial thickness. The radial thickness may be defined as the minimum distance between the frame outer surface and the frame inner surface, such as in the x / y plane.

[0147] The peripheral wall may have a radial thickness greater than or equal to 0.5 millimetres. The peripheral wall may have a radial thickness greater than or equal to 1.5 millimetres. The peripheral wall may have a radial thickness greater than or equal to 2.5 millimetres.

[0148] The peripheral wall may have a radial thickness less than or equal to 3.5 millimetres. The peripheral wall may have a radial thickness less than or equal to 2.5 millimetres.

[0149] The peripheral wall may have a radial thickness between 0.5 millimetres and 3.5 millimetres. The peripheral wall may have a radial thickness between 0.5 millimetres and 2.5 millimetres.

[0150] Advantageously, the peripheral wall having a radial thickness between 0.5 millimetres and 3.5 millimetres has been found to provide good structural strength for the aerosol-generating article whilst not using excess amounts of material which may increase manufacturing costs, and may limit the amount of heat that is undesirably transferred to the frame rather than the aerosol-generating substrate.

[0151] The frame may be made from or comprise a biodegradable material. The frame may be made entirely from a biodegradable material.

[0152] The frame may be made from or comprise a cellulosic material. The cellulosic material may comprise a sheet of cellulosic material. The cellulosic material may comprise cellulose fibres. The cellulosic material may be paper, paperboard, or cardboard. The frame may be made from or comprise a plant material, such as tobacco. The frame may be made entirely from a cellulosic material.

[0153] The aerosol-generating article may comprise one or more susceptor materials. The frame may comprise one or more susceptor materials. The one more susceptor materials may be in thermal contact with the aerosol-generating substrate. The one more susceptor materials may be in thermal contact with the cavity. The one or more susceptor materials may be incorporated within the material of the frame. For example, the one or more susceptor material may be incorporated within the peripheral wall of the frame.

[0154] The one or more susceptor materials may be one or more particles, strips, threads, or wires of susceptor material. The one or more susceptor materials may be one or more sheets or layers of susceptor material. The one of more sheets or layers of susceptor material may be in the form of a mesh of susceptor material.

[0155] The susceptor material, in whatever form, may comprise one or more materials selected from the list consisting of: aluminium, iron and iron alloys, nickel and nickel alloys, cobalt alloys, stainless steel alloys, copper alloys, carbon, expanded carbon, and graphite.

[0156] The frame may have a thickness greater than or equal to 50 percent of the thickness of the aerosol-generating article. The frame may have a thickness greater than or equal to 70 percent of the thickness of the aerosol-generating article. The frame may have a thickness greater than or equal to 90 percent of the thickness of the aerosol-generating article. The frame may have a thickness greater than or equal to 95 percent of the thickness of the aerosol-generating article.

[0157] The frame may have a thickness less than or equal to 95 percent of the thickness of the aerosol-generating article. The frame may have a thickness less than or equal to 90 percent of the thickness of the aerosol-generating article. The frame may have a thickness less than or equal to 70 percent of the thickness of the aerosol-generating article.

[0158] The frame may have a thickness between 50 percent of the thickness of the aerosolgenerating article and 95 percent of the thickness of the aerosol-generating article. The frame may have a thickness between 70 percent of the thickness of the aerosol-generating article and 95 percent of the thickness of the aerosol-generating article.

[0159] The frame may have a thickness greater than or equal to 1 millimetre, greater than or equal to 2 millimetres, greater than or equal to 3 millimetres, or greater than or equal to 4 millimetres. The frame may have a thickness less than or equal to 5.5 millimetres, less than or equal to 4.5 millimetres, less than or equal to 3.5 millimetres, less than or equal to 2.5 millimetres, or less than or equal to 1 .5 millimetres. The frame may have a thickness between 1 millimetre and 5.5 millimetres. Preferably, the frame may have a thickness between 1 .5 millimetres and 5.5 millimetres.

[0160] The frame may have a length that is equal to the length of the aerosol-generating article. The frame may have a length that is at least 90 percent of the length of the aerosol-generating article. The frame may have a length that is at least 95 percent of the length of the aerosol-generating article.

[0161] The frame may have a width that is equal to the width of the aerosol-generating article. The frame may have a width that is at least 90 percent of the width of the aerosol-generating article.

[0162] The frame may be a unitary component. Alternatively, the frame may comprise two or more layers. That is, the frame may have a laminated structure. Advantageously, the properties of each layer may be individually optimised depending on the relative distance between the layer and aerosolgenerating substrate or heater of the aerosol-generating device.

[0163] The frame may comprise a first frame layer and a second frame layer. The first frame layer and the second frame layer may be the only layers of the frame. That is, the frame may comprise no more than two layers or may comprise exactly two layers. The frame aperture may be defined through both the first frame layer and the second frame layer.

[0164] The frame may comprise a first frame layer, a second frame layer and a third frame layer. The second frame layer may be positioned between the first frame layer and the third frame layer. The first frame layer, the second frame layer and the third frame layer may be the only layers of the frame. That is, the frame may comprise no more than three layers or may comprise exactly three layers.

[0165] The first planar external surface may be a planar upper surface and the second planar external surface may be a planar lower surface. The first planar external surface may be positioned parallel to the second planar external surface. The first planar external surface may extend in the x / y plane. The second planar external surface may extend in the x / y plane. The second planar external surface may be spaced from the first planar external surface in the z-direction or transverse direction. The distance between the first planar external surface and the second planar external surface in the z-direction or transverse direction may define the thickness of the aerosol-generating article.

[0166] The aerosol-generating article may comprise an outer wrapper. The outer wrapper may be hydrophobic. The outer wrapper may comprise a hydrophobic material.

[0167] The outer wrapper may define or form the first planar external surface. The outer wrapper may define or form the second planar external surface. The outer wrapper may define or form both the first planar external surface and the second planar external surface.

[0168] The outer wrapper may circumscribe or encircle the frame. The outer wrapper may be in physical contact with, and may be bonded to, the frame. The outer wrapper may overlie opposing ends of the cavity. The outer wrapper may define or form opposing end walls of the cavity, such as the first cavity end wall and the second cavity end wall. That is, the frame and the outer wrapper may collectively define the cavity.

[0169] The outer wrapper may circumscribe or encircle the frame and the aerosol-generating substrate layer. The outer wrapper may be in physical contact with, and may be bonded to, both the frame and the aerosol-generating substrate layer.

[0170] The outer wrapper may circumscribe or encircle the frame, the first aerosol-generating substrate layer and the second aerosol-generating substrate layer. The outer wrapper may be in physical contact with, and may be bonded to, both the first aerosol-generating substrate layer and the second aerosol-generating substrate layer.

[0171] The aerosol-generating article may comprise a first planar external layer and a second planar external layer. The first planar external layer may be an upper layer and the second planar external layer may be a lower layer.

[0172] The first planar external layer may define or form the first planar external surface. The first planar external layer may extend in the x / y plane. The second planar external layer may define or form the second planar external surface. The second planar external layer may extend in the x / y plane.

[0173] The first planar external layer may be in physical contact with, and may be bonded to, the frame. The first planar external layer may overlie an end of the cavity. The first planar external layer may define or form a wall of the cavity, such as the first cavity end wall. The second planar external layer may be in physical contact with, and may be bonded to, the frame. The second planar external layer may overlie an end of the cavity. The second planar external layer may define or form a wall of the cavity, such as the second cavity end wall.

[0174] The first planar external layer and the second planar external layer may overlie opposing ends of the cavity. The first planar external layer and the second planar external layer may define or form opposing end walls of the cavity, such as the first cavity end wall and the second cavity end wall. That is, the frame, the first planar external layer and the second planar external layer may collectively define the cavity.

[0175] The first planar external layer may be spaced, such as in a transverse direction, from the frame. For example, the aerosol-generating substrate layer or the first aerosol-generating substrate layer may be positioned between the first planar external layer and the frame. The first planar external layer may be in physical contact with, and may be bonded to, the aerosol-generating substrate layer or the first aerosol-generating substrate layer.

[0176] The second planar external layer may be spaced, such as in a transverse direction, from the frame. For example, the aerosol-generating substrate layer or the second aerosol-generating substrate layer may be positioned between the second planar external layer and the frame. The second planar external layer may be in physical contact with, and may be bonded to, the aerosolgenerating substrate layer or the second aerosol-generating substrate layer.

[0177] The first planar external layer may be hydrophobic. The first planar external layer may comprise a hydrophobic material. The second planar external layer may be hydrophobic. The second planar external layer may comprise a hydrophobic material.

[0178] One or more of the outer wrapper, the first planar external layer and the second planar external layer may comprise, or be made from, a cellulosic material. The cellulosic material may be paper, cigarette paper, tobacco paper, cardboard, wood, textile, natural fibres or artificial fibres.

[0179] One or more of the outer wrapper, the first planar external layer and the second planar external layer may comprise an aerosol-generating substrate as described herein.

[0180] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a thickness greater than or equal to 25 micrometres, greater than or equal to 30 micrometres, greater than or equal to 35 micrometres, greater than or equal to 40 micrometres, or greater than or equal to 45 micrometres.

[0181] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a thickness less than or equal to 55 micrometres, less than or equal to 50 micrometres, less than or equal to 45 micrometres, less than or equal to 40 micrometres, or less than or equal to 35 micrometres.

[0182] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a thickness between 25 micrometres and 55 micrometres, between 25 micrometres and 45 micrometres, or between 30 micrometres and 45 micrometres.

[0183] One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a length substantially the same as the length of the frame. One or more of the outer wrapper, the first planar external layer and the second planar external layer may have a length substantially the same as the length of the aerosol-generating article.

[0184] One or more of the first planar external layer and the second planar external layer may have a width substantially the same as the width of the frame. One or more of the first planar external layer and the second planar external layer may have a width substantially the same as the width of the aerosol-generating article.

[0185] The cavity may have a thickness greater than or equal to 0.5 millimetres. The cavity may have a thickness greater than or equal to 1.5 millimetres. The cavity may have a thickness greater than or equal to 2.5 millimetres. The cavity may have a thickness greater than or equal to 3.5 millimetres.

[0186] The cavity may have a thickness less than or equal to 4.5 millimetres. The cavity may have a thickness less than or equal to 3.5 millimetres. The cavity may have a thickness less than or equal to 2.5 millimetres. The cavity may have a thickness less than or equal to 1 .5 millimetres.

[0187] The cavity may have a thickness between 0.5 millimetres and 4.5 millimetres. The cavity may have a thickness between 1 millimetre and 4.5 millimetres. Preferably, the cavity may have a thickness between 2.8 millimetres and 3.3 millimetres.

[0188] The cavity may have a length greater than or equal to 14 millimetres. The cavity may have a length equal to a greater than 18 millimetres. The cavity may have a length greater than or equal to 22 millimetres. The cavity may have a thickness greater than or equal to 30 millimetres. The cavity may have a thickness greater than or equal to 38 millimetres.

[0189] The cavity may have a length less than or equal to 40 millimetres. The cavity may have a thickness less than or equal to 34 millimetres. The cavity may have a thickness less than or equal to 28 millimetres. The cavity may have a thickness less than or equal to 22 millimetres. The cavity may have a thickness less than or equal to 18 millimetres.

[0190] The cavity may have a length between 14 millimetres and 40 millimetres. The cavity may have a length between 14 millimetres and 34 millimetres. . The cavity may have a length between 24 millimetres and 28 millimetres.

[0191] The cavity may have a width greater than or equal to 4.5 millimetres. The cavity may have a width greater than or equal to 7 millimetres. The cavity may have a width greater than or equal to 11 millimetres.

[0192] The cavity may have a width less than or equal to 13 millimetres. The cavity may have a width less than or equal to 11 millimetres. The cavity may have a width less than or equal to 7 millimetres. The cavity may have a width less than or equal to 5 millimetres.

[0193] The cavity may have a width between 4.5 millimetres and 13 millimetres. The cavity may have a width between 7 millimetres and 10 millimetres. The cavity may have a width between 7.5 millimetres and 8.5 millimetres.

[0194] The cavity may have a length between 14 millimetres and 40 millimetres, a width between 4.5 millimetres and 13 millimetres, and a thickness between 0.5 millimetres and 4.5 millimetres.

[0195] Preferably, the cavity may have a length between 20 millimetres and 30 millimetres, a width between 7 millimetres and 10 millimetres, and a thickness between 2.5 millimetres and 4 millimetres. Most preferably, the cavity may have a length of 26 millimetres, a width of 8 millimetres, and a thickness of 3.1 millimetres.

[0196] The cavity may have a volume of greater than or equal to 30 cubic millimetres, greater than or equal to 100 cubic millimetres, greater than or equal to 300 cubic millimetres, greater than or equal to 500 cubic millimetres, greater than or equal to 700 cubic millimetres, greater than or equal to 900 cubic millimetres, greater than or equal to 1000 cubic millimetres, greater than or equal to 2000 cubic millimetres, or greater than or equal to 30 cubic millimetres.

[0197] The cavity may have a volume of less than or equal to 3500 cubic millimetres, less than or equal to 2500 cubic millimetres, less than or equal to 1500 cubic millimetres, less than or equal to 1000 cubic millimetres, less than or equal to 800 cubic millimetres, less than or equal to 600 cubic millimetres, less than or equal to 500 cubic millimetres, less than or equal to 400 cubic millimetres, or less than or equal to 300 cubic millimetres.

[0198] The cavity may have a volume between 30 cubic millimetres and 3500 cubic millimetres. The cavity may have a volume between 30 cubic millimetres and 2500 cubic millimetres. The cavity may have a volume between 100 cubic millimetres and 1500 cubic millimetres. The cavity may have a volume between 100 cubic millimetres and 1000 cubic millimetres.

[0199] As defined above, aerosol-generating articles according to the present invention comprise an air inlet and an air outlet. The air inlet may be defined by a front wall of the aerosol-generating article. The air inlet may be defined by, and may extend through, the frame. The air inlet may be defined by the peripheral wall of the frame. The air inlet may extend through the peripheral wall of the frame. The air outlet may be defined by a back wall of the aerosol-generating article. The air outlet may be defined by, and may extend through, the frame. The air outlet may be defined by the peripheral wall of the frame. The outlet may extend though the peripheral wall of the frame.

[0200] The air inlet may have a round cross-section, a circular cross-section, an oval cross-section, a square cross-section, or a rectangular cross-section. The air outlet may have a round cross-section, a circular cross-section, an oval cross-section, a square cross-section, or a rectangular cross-section.

[0201] The air inlet may be defined by, and may extend through, the first planar external surface. The air inlet may be defined by, and may extend through, the outer wrapper. The air inlet may be defined by, and may extend through, the outer wrapper and the aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the outer wrapper and the first aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the first planar external layer and the aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the first planar external layer and the first aerosol-generating substrate layer.

[0202] The air inlet may be defined by, and may extend through, the second planar external surface. The air inlet may be defined by, and may extend through, the outer wrapper and the second aerosolgenerating substrate layer. The air inlet may be defined by, and may extend through, the second planar external layer and the aerosol-generating substrate layer. The air inlet may be defined by, and may extend through, the second planar external layer and the second aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the first planar external surface. The air outlet may be defined by, and may extend through, the outer wrapper. The air outlet may be defined by, and may extend through, the outer wrapper and the aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the outer wrapper and the first aerosolgenerating substrate layer. The air outlet may be defined by, and may extend through, the first planar external layer and the aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the first planar external layer and the first aerosol-generating substrate layer.

[0203] The air outlet may be defined by, and may extend through, the second planar external surface. The air outlet may be defined by, and may extend through, the outer wrapper and the second aerosolgenerating substrate layer. The air outlet may be defined by, and may extend through, the second planar external layer and the aerosol-generating substrate layer. The air outlet may be defined by, and may extend through, the second planar external layer and the second aerosol-generating substrate layer.

[0204] One or both of the air inlet and the air outlet may have an equivalent diameter greater than or equal to 0.1 millimetres, greater than or equal to 0.4 millimetres, greater than or equal to 0.7 millimetres, or greater than or equal to 1.0 millimetres.

[0205] One or both of the air inlet and the air outlet may have an equivalent diameter less than or equal to 3 millimetres, less than or equal to 2.7 millimetres, less than or equal to 2.4 millimetres, less than or equal to 2.1 millimetres. The air inlet may have an equivalent diameter less than or equal to 2.7 millimetres, less than or equal to 1 .8 millimetres, or less than or equal to 1 .5 millimetres.

[0206] One or both of the air inlet and the air outlet may have an equivalent diameter between 0.1 millimetres and 3 millimetres, between 0.1 millimetres and 2.4 millimetres, between 0.4 millimetres and 2.1 millimetres, between 0.4 millimetres and 1.8 millimetres, between 0.7 millimetres and 1.5 millimetres, or between 1.0 millimetres and 1.5 millimetres.

[0207] The air inlet may have a width less than a width of the cavity. The air outlet may have a width less than a width of the cavity. The air inlet may have a thickness less than a thickness of the cavity. The air outlet may have a thickness less than a thickness of the cavity.

[0208] One or both of the air inlet and the air outlet may a width of between 0.3 millimetres and 3 millimetres or between 0.5 millimetres and 2 millimetres.

[0209] One or both of the air inlet and the air outlet may have a thickness of between 0.3 millimetres and 3 millimetres or between 0.5 millimetres and 2 millimetres.

[0210] Preferably, the air inlet may have a width of between 0.3 millimetres and 3 millimetres, and a thickness of between 0.3 millimetres and 3 millimetres.

[0211] Preferably, the air outlet may have a width of between 0.3 millimetres and 3 millimetres, and a thickness of between 0.3 millimetres and 3 millimetres.

[0212] Advantageously, an aerosol-generating article having an air outlet or air inlet with a width of between 0.3 millimetres and 3 millimetres and a thickness of between 0.3 millimetres and 3 millimetres may provide for a relatively large inlet or outlet opening while allowing for improved retention of the aerosol-generating substrate within the aerosol-generating article. Improved retention of the aerosol- generating substrate within the aerosol-generating article may reduce the risk of aerosol-generating substrate falling out of the aerosol-generating article.

[0213] A ratio of the width of the air inlet to the thickness of the air inlet may be between 0.33 and 3. A ratio of the width of the air inlet to the thickness of the air inlet may be between 0.5 and 1 .5. A ratio of the width of the air inlet to the thickness of the air inlet may be between 0.75 and 1 .25.

[0214] A ratio of the width of the air outlet to the thickness of the air outlet may be between 0.33 and 3. A ratio of the width of the air outlet to the thickness of the air outlet may be between 0.5 and 1 .5. A ratio of the width of the air outlet to the thickness of the air outlet may be between 0.75 and 1 .25.

[0215] In alternative embodiments, a ratio of the width of the air outlet to the thickness of the air outlet may be at least 3.5, more preferably at least 4.

[0216] The provision of a relatively wide air outlet may be particularly advantageous for aerosolgenerating articles according to the present invention which comprise an aerosol-generating substrate having a relatively high aerosol former content. The relatively high width of the air outlet ensures sufficient airflow through the aerosol-generating article, reduces turbulence downstream of the aerosol-generating substrate and reduces the time that the aerosol takes to pass through the air outlet downstream of the aerosol-generating substrate. The cooling of the aerosol can be controlled so that the aerosol is still hot when it comes into contact with any ventilation air. Advantageously, the risk of aerosol condensation inside the aerosol-generating system during use can therefore be reduced.

[0217] The thickness can however be retained at a sufficiently small level to protect any aerosolgenerating substrate within the cavity and to prevent the aerosol-generating substrate from falling out through the air outlet.

[0218] As defined above, aerosol-generating articles of the present invention define an airflow pathway through the cavity from the air inlet to the air outlet.

[0219] Preferably, the length of the airflow pathway is less than the length of the aerosol-generating article. The length of the airflow pathway may be equal to or less than 90 percent of the length of the aerosol-generating article, optionally equal to or less than 80 percent of the length of the aerosol-generating article, optionally equal to or less than 70 percent of the length of the aerosolgenerating article, optionally equal to or less than 60 percent of the length of the aerosolgenerating article, or optionally equal to or less than 50 percent of the length of the aerosolgenerating article.

[0220] Advantageously, the provision of a relatively short airflow pathway facilitates the provision of the air inlet and air outlet as close as possible to the aerosol-generating substrate. Advantageously, this may increase or maximise the temperature of the airflow through the air inlet and the air outlet, which may reduce or minimise condensation of aerosol that may otherwise occur as a result of turbulent airflow at the air inlet and the air outlet. It is desirable to minimise turbulent airflow, since this otherwise promotes undesirable condensation of aerosol within the aerosol-generating article. It is particularly advantageous to reduce condensation in view of the relatively high aerosol former content of the aerosol-generating substrate in the aerosolgenerating article of the present invention. The aerosol-generating article may comprise a plurality of air inlets. One or each of the air inlets may have one or more of the features of the air inlet described herein.

[0221] The aerosol-generating article may comprise a plurality of air outlets. One or each of the air outlets may have one or more of the features of the air outlet described herein.

[0222] The aerosol-generating article may comprise a filter element positioned downstream of the aerosol-forming substrate. The aerosol-generating article may comprise a filter element positioned downstream of the cavity. The aerosol-generating article may comprise a filter element at least partially positioned within the air outlet. The aerosol-generating article may comprise a filter element positioned within, and may be positioned at a downstream end of, the cavity.

[0223] The aerosol-generating article may comprise a filter element positioned upstream of the aerosol-forming substrate. The aerosol-generating article may comprise a filter element positioned upstream of the cavity. The aerosol-generating article may comprise a filter element at least partially positioned within the air inlet. The aerosol-generating article may comprise a filter element positioned within, and may be positioned at an upstream end of, the cavity.

[0224] The filter element may comprise one or more segments of a fibrous filtration material. Suitable fibrous filtration materials would be known to the skilled person. The filter element may comprise a cellulose acetate.

[0225] Preferably, the portion of the aerosol-generating article that is downstream of the cavity comprises a hollow portion defining a longitudinal channel providing an unrestricted flow channel. This may include or consist of the air outlet.

[0226] Preferably, the portion of the aerosol-generating article that is downstream of the cavity has a resistance to draw (RTD) of less than or equal to 25 mm H2O, more preferably less than or equal to 15 mm H2O, more preferably less than or equal to 10 mm H2O, more preferably less than or equal to 5 mm H2O. This relatively low level of RTD will typically be achieved through the provision of an unrestricted flow channel with minimal or no fibrous filtration material downstream of the cavity.

[0227] The resistance to draw (RTD) of a component of the aerosol-generating article is measured in accordance with ISO 6565-2015. The RTD refers the pressure required to force air through the full length of a component.

[0228] The provision of a relatively low RTD downstream of the cavity minimises filtration of the aerosol and thereby maximises delivery of aerosol to the consumer. The hollow flow channel downstream of the cavity provides an empty volume of space in which nucleation and growth of aerosol particles is favoured. This may further enhance aerosol generation and delivery. This effect has been found to be particularly beneficial for aerosol-generating substrates having a relatively high aerosol former content, as in the present invention. The relatively low RTD downstream of the cavity provides minimal removal of the aerosol former from the aerosol generated from the aerosolgenerating substrate. This enables a desirable volume of aerosol to be delivered to the consumer and which has a good balance between nicotine and aerosol former. A ratio between the length and the thickness of the aerosol-generating article, and between the width and the thickness of the aerosol-generating article may be greater than 2:1 , greater than 5:1 , greater than 10:1 , greater than 12:1 , or greater than 15:1.

[0229] A ratio between the length and the thickness of the aerosol-generating article, and between the width and the thickness of the aerosol-generating article may be less than 15:1 , less than 12:1 , less than 10:1 , less than 5:1 , or less than 2.5:1

[0230] A ratio between the length and the thickness of the aerosol-generating article, and between the width and the thickness of the aerosol-generating article may be between 2:1 and 15:1 , between 2:1 and 12:1 , between 2:1 and 10:1 , or between 5:1 and 10:1.

[0231] A ratio between the length and the width of the aerosol-generating article may be greater than 1 :1 , greater than 2:1 , greater than 3:1 , greater than 4:1 , or greater than 5:1.

[0232] A ratio between the length and the width of the aerosol-generating article may be less than 10:1 , less than 8:1 , less than 5:1 , less than 4:1 , less than 3:1 , or less than 2:1.

[0233] A ratio between the length and the width of the aerosol-generating article may be between 1 : 1 and 10:1 , between 1 :1 and 5:1 , between 1 :1 and 4:1 , between 1 :1 and 3:1 , between 2:1 and 4:1 , or between 2:1 and 3:1 .

[0234] The aerosol-generating article may have a length greater than or equal to 15 millimetres, greater than or equal to 20 millimetres, greater than or equal to 25 millimetres, greater than or equal to 30 millimetres, greater than or equal to 35 millimetres, or greater than or equal to 40 millimetres.

[0235] The aerosol-generating article may have a length less than or equal to 45 millimetres, less than or equal to 40 millimetres, less than or equal to 35 millimetres, or less than or equal to 30 millimetres.

[0236] The aerosol-generating article may have a length between 15 millimetres and 45 millimetres, between 20 millimetres and 40 millimetres, between 20 millimetres and 35 millimetres, or between 25 millimetres and 30 millimetres.

[0237] The aerosol-generating article may have a width equal to greater than 3 millimetres, greater than 5 millimetres, greater than 7.5 millimetres, greater than 9 millimetres, greater than 11 millimetres, or greater than 13 millimetres.

[0238] The aerosol-generating article may have a width less than or equal to 17 millimetres, less than or equal to 15 millimetres, less than or equal to 12.5 millimetres, less than or equal to 11 millimetres, or less than or equal to 9 millimetres.

[0239] The aerosol-generating article may have a width between 3 millimetres and 17 millimetres, between 5 millimetres and 15 millimetres, between 7.5 millimetres and 12.5 millimetres, or between 9 millimetres and 11 millimetres.

[0240] The aerosol-generating article may have a thickness equal to greater than 1 millimetre, greater than or equal to 1.5 millimetres, greater than or equal to 2 millimetres, greater than or equal to 2.5 millimetres, greater than or equal to 3 millimetres, greater than or equal to 3.5 millimetres, greater than or equal to 4 millimetres, or greater than or equal to 4.5 millimetres. The aerosol-generating article may have a thickness less than or equal to 5.5 millimetres, less than or equal to 5 millimetres, less than or equal to 4.5 millimetres, less than or equal to 4 millimetres, less than or equal to 3.5 millimetres, less than or equal to 3 millimetres, less than or equal to 2.5 millimetres, or less than or equal to 2 millimetres.

[0241] The aerosol-generating article may have a thickness between 1 millimetres and 5 millimetres, between 1.5 millimetres and 5 millimetres, between 2 millimetres and 4.5 millimetres, between 2.5 millimetres and 4 millimetres, or between 3 millimetres and 3.5 millimetres.

[0242] According to the present disclosure, there is provided an aerosol-generating device for receiving an aerosol-generating article as disclosed herein. The aerosol-generating device comprises a cavity dimensioned to receive at least a portion of the aerosol-generating article. The aerosolgenerating device comprises a heater or heating means, a power source for supplying power to the heater or heating means, and a controller to control a supply of power to the heater or heating means. The heater is preferably configured to heat the aerosol-generating substrate to form an aerosol, for example an inhalable aerosol.

[0243] Preferably, the heater is configured to heat the aerosol-generating substrate to a maximum temperature of 250 degrees Celsius, more preferably to a maximum temperature of 210 degrees Celsius. As described above, the use of relatively low temperatures in the aerosol-generating device has been found to be particularly effective for the heating of aerosol-generating substrates comprising exogenous nicotine and a relatively high level of aerosol former.

[0244] According to the present disclosure, an aerosol-generating system comprises an aerosolgenerating device as disclosed herein and an aerosol-generating article as disclosed herein. The system may comprise a plurality of such articles for use with the aerosol-generating device.

[0245] As used herein, the term “aerosol-generating article” refers to an article comprising an aerosolgenerating substrate. The article may be heated in use to produce and deliver an inhalable aerosol to a consumer.

[0246] As used herein, the term “aerosol-generating substrate” refers to a substrate capable of releasing volatile compounds upon heating, for example compounds which, in use, cool and condense to generate an aerosol.

[0247] As used herein, the term “aerosol-generating device” refers to a device that, in use, interacts with, for example heats, an aerosol-generating substrate of an aerosol-generating article to generate an aerosol.

[0248] As used herein, the term “planar” refers to a feature generally formed in a single Euclidean plane and not wrapped around or otherwise conformed to fit a curved or other non-planar shape. A planar surface may extend in two dimensions in a single Euclidean plane. A planar object may extend in two dimensions in a single Euclidean plane substantially more than in a third dimension perpendicular to the plane. More specifically, a planar object may extend in a first dimension and a second dimension perpendicular to the first dimension at least two, five or ten times further than the object extends in a third dimension perpendicular to the first and second dimensions. As used herein, the term “transverse” refers to a direction extending between the first planar external surface and the second planar external surface. The transverse direction may also be referred to as the “z-direction”.

[0249] As used herein, the term “longitudinal” refers to a direction that is perpendicular to the transverse direction. For example, a direction between a front wall and a back wall of the aerosol-generating article. The longitudinal direction may also be referred to as the “x-direction”.

[0250] As used herein, the term “lateral” refers to a direction that is perpendicular to the transverse direction and the longitudinal direction. For example, a direction from a first side wall to a second side wall of the aerosol-generating article. The lateral direction may also be referred to as the “y-direction”.

[0251] As used herein, the term “thickness” refers to a maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the transverse direction.

[0252] As used herein, the term “length” refers to a maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the longitudinal direction.

[0253] As used herein, the term “width” refers to a maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the lateral direction.

[0254] As used herein, the terms “upstream” and “downstream” refer to the relative positions of components, or portions of components, of the aerosol-generating article in relation to the direction in which the air or aerosol is transported through the aerosol-generating article during use.

[0255] As used herein, the term “bulk density” may refer to the total weight of the aerosol-generating substrate divided by the bulk volume of the aerosol-generating substrate.

[0256] As used herein, the term “aerosol former” may refer to any suitable known compound or mixture of compounds that, in use, facilitates formation of an aerosol. The aerosol may be a dense and stable aerosol. The aerosol may be substantially resistant to thermal degradation at the operating temperature of the aerosol-generating substrate or aerosol-generating article.

[0257] As used herein, the term “aerosol former content” may refer to aerosol former content in percent on a dry weight basis, unless otherwise specified.

[0258] As used herein, a "susceptor" refers to a conductive element that heats up when subjected to a changing magnetic field. This may be the result of eddy currents induced in the susceptor element and / or hysteresis losses.

[0259] As used herein, the term “hydrophobic” refers to a surface exhibiting water repelling properties. One useful way to determine this is to measure the water contact angle. The “water contact angle” is the angle, conventionally measured through the liquid, where a liquid / vapour interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via the Young equation.

[0260] As used herein, the term “equivalent diameter” of an opening or an aperture is used herein to denote the diameter of a circular opening or aperture having the same cross-sectional area as the opening or aperture.

[0261] The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein. Example Ex1 . An aerosol-generating article for use with an aerosol-generating device to generate an inhalable aerosol, 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; an aerosol-generating substrate comprising exogenous nicotine and one or more aerosol formers; and an air inlet and an air outlet, and an airflow passage extending between the air inlet and the air outlet through the cavity.

[0262] Example Ex2. An aerosol-generating article according to example Ex1 , wherein the article has an article length, an article width, and an article thickness, the article length and the article width being at least two times the article thickness.

[0263] Example Ex3. An aerosol-generating article according to example Ex1 , wherein the article length extends in an article length direction, the article width extends in an article width direction, and the article thickness extends in an article thickness direction, and wherein the article length direction, the article width direction, and the article thickness direction are mutually perpendicular.

[0264] Example Ex4. An aerosol-generating article according to any preceding example, wherein the article length and the article width are at least 3, 4 or 5 times the article thickness.

[0265] Example Ex5. An aerosol-generating article according to any preceding example, wherein the article is substantially cuboid in shape.

[0266] Example Ex6. An aerosol-generating article according to any preceding example, wherein the total aerosol former content of the aerosol-generating substrate is at least 40 percent by weight on a dry weight basis.

[0267] Example Ex7. An aerosol-generating article according to example Ex6, wherein the total aerosol former content of the aerosol-generating substrate is at least 45 percent by weight, or at least 50 percent by weight, on a dry weight basis.

[0268] Example Ex8. An aerosol-generating article according to any preceding example, wherein the total aerosol former content of the aerosol-generating substrate is less than or equal to 70 percent by weight, or less than or equal to 65 percent by weight, or less than or equal to 60 percent by weight, on a dry weight basis.

[0269] Example Ex9. An aerosol-generating article according to any preceding example, wherein the aerosol former comprises glycerol.

[0270] Example Ex10. An aerosol-generating article according to any preceding example, wherein the aerosol-generating substrate has a total exogenous nicotine content of at least 0.5 percent by weight, for example at least 1 percent by weight, or at least 1 .5 percent by weight, or at least 2 percent by weight, on a dry weight basis. Example Ex11 . An aerosol-generating article according to any preceding example, wherein the aerosol-generating substrate has a total exogenous nicotine content of less than or equal to 10 percent by weight, for example less than or equal to 8 percent by weight, or less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight, on a dry weight basis.

[0271] Example Ex12. An aerosol-generating article according to any of examples Ex1 to Ex10, wherein the aerosol-generating substrate is substantially free from tobacco.

[0272] Example Ex13. An aerosol-generating article according to any preceding example, wherein the aerosol-generating substrate further comprises one or more flavourants.

[0273] Example Ex14. An aerosol-generating article according to any preceding example, wherein the aerosol-generating substrate comprises one or more cellulose based agents.

[0274] Example Ex15. An aerosol-generating article according to example Ex14, wherein the aerosolgenerating substrate has a total cellulose based agent content of at least 25 percent by weight, for example at least 36 percent by weight, or at least 38 percent by weight, or at least 40 percent by weight, on a dry weight basis.

[0275] Example Ex16. An aerosol-generating article according to example Ex14 or Ex15, wherein the aerosol-generating substrate has a total cellulose based agent content of less than or equal to 52 percent by weight, for examples less than or equal to 50 percent by weight, or less than or equal to 48 percent by weight, or less than or equal to 46 percent by weight, or less than or equal to 44 percent by weight, on a dry weight basis.

[0276] Example Ex17. An aerosol-generating article according to any of examples Ex14 to Ex16, wherein the aerosol-generating substrate comprises one or more cellulose based film-forming agents.

[0277] Example Ex18. An aerosol-generating article according to example Ex17, wherein the one or more cellulose based film-forming agents are selected from carboxymethyl cellulose (CMC), ethylcellulose (EC), hydroxyethyl cellulose (HEC), hydroxyethyl methylcellulose (HEMC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), and methylcellulose (MC).

[0278] Example Ex19. An aerosol-generating article according to example Ex17 or Ex18 wherein the aerosol-generating substrate has a total cellulose based film-forming agent content of at least 15 percent by weight, for example at least 20 percent by weight, or at least 25 percent by weight, on a dry weight basis.

[0279] Example Ex20. An aerosol-generating article according to any of examples Ex17 to Ex19 wherein the aerosol-generating substrate has a any of total cellulose based film-forming agent content of less than or equal to 40 percent by weight, less than or equal to 35 percent by weight, or less than or equal to 30 percent by weight, on a dry weight basis.

[0280] Example Ex21. An aerosol-generating article according to any of examples Ex14 to Ex20, wherein the aerosol-generating substrate comprises hydroxypropyl methylcellulose.

[0281] Example Ex22. An aerosol-generating article according to example Ex21 wherein the aerosolgenerating substrate has a hydroxypropyl methylcellulose content of at least 2 percent by weight, for example at least 3 percent by weight, or at least 4 percent by weight, or at least 5 percent by weight, on a dry weight basis. Example Ex23. An aerosol-generating article according to any of examples Ex14 to Ex22, wherein the aerosol-generating substrate comprises sodium carboxymethyl cellulose.

[0282] Example Ex24. An aerosol-generating article according to example Ex23 wherein the aerosolgenerating substrate has a carboxymethyl cellulose content of at least 2 percent by weight, for example at least 3 percent by weight, or at least 4 percent by weight, or at least 5 percent by weight, on a dry weight basis.

[0283] Example Ex25. An aerosol-generating article according to example Ex23 or Ex24, wherein the aerosol-generating substrate has a carboxymethyl cellulose content of less than or equal to 12 percent by weight, for example, less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, or less than or equal to 6 percent by weight, on a dry weight basis.

[0284] Example Ex26. An aerosol-generating article according to any of examples Ex14 to Ex25, wherein the aerosol-generating substrate further comprises one or more cellulose based strengthening agents.

[0285] Example Ex27. An aerosol-generating article according to example EX26 wherein the one or more cellulose based strengthening agents are selected from cellulose fibres, cellulose powder and microcrystalline cellulose (MCC).

[0286] Example Ex28. An aerosol-generating article according to example Ex26 or Ex27, wherein the aerosol-generating substrate has a total cellulose based strengthening agent content of at least 5 percent by weight, for example at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0287] Example Ex29. An aerosol-generating article according to any of examples Ex26 to Ex28, wherein the aerosol-generating substrate has a total cellulose based strengthening agent content of less than or equal to 30 percent by weight, for example, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight, on a dry weight basis.

[0288] Example Ex30. An aerosol-generating article according to any of examples Ex26 to Ex29, wherein the aerosol-generating substrate comprises cellulose fibres.

[0289] Example Ex31. An aerosol-generating article according to example Ex30, wherein the cellulose fibres have a length of at least 0.2 millimetres, for example at least 0.5 millimetres, at least 0.7 millimetres, or at least 0.9 millimetres.

[0290] Example Ex32. An aerosol-generating article according to example Ex30 or Ex31 , wherein the aerosol-generating substrate has a cellulose fibre content of at least 2 percent by weight, for example, at least 5 percent by weight, at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0291] Example Ex33. An aerosol-generating article according to any of examples Ex27 to Ex32, wherein the aerosol-generating substrate comprises microcrystalline cellulose.

[0292] Example Ex34. An aerosol-generating article according to example Ex33, wherein the microcrystalline cellulose has a D50 size of at least 5 micrometres, for example at least 10 micrometres, for example at least 15 micrometres. Example Ex35. An aerosol-generating article according to example Ex33 or Ex34, wherein the aerosol-generating substrate has a microcrystalline cellulose content of at least 2 percent by weight, for example at least 5 percent by weight, or at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0293] Example Ex36. An aerosol-generating article according to any of examples Ex27 to Ex35, wherein the aerosol-generating substrate comprises cellulose powder.

[0294] Example Ex37. An aerosol-generating article according to example Ex36, wherein the cellulose powder has D50 size of at least 25 micrometres, for example at least 30 micrometres, or at least 35 micrometres.

[0295] Example Ex38. An aerosol-generating article according to example Ex36 or Ex37, wherein the aerosol-generating substrate has a cellulose powder content of at least 2 percent by weight, for example at least 5 percent by weight, at least 10 percent by weight, or at least 15 percent by weight, on a dry weight basis.

[0296] Example Ex39. An aerosol-generating article according to any preceding example, wherein the aerosol-generating substrate further comprises one or more carboxylic acids.

[0297] Example Ex40. An aerosol-generating article according to example Ex38, wherein the aerosolgenerating substrate has a total carboxylic acid content of at least 1 percent by weight, at least 1 .5 percent by weight, or at least 2 percent by weight.

[0298] Example Ex41 . An aerosol-generating article according to any preceding example, wherein the aerosol-generating substrate further comprises one or more non-cellulose based thickening agents.

[0299] Example Ex42. An aerosol-generating article according to example Ex40, wherein the one or more non-cellulose based thickening agents are selected from alginates, gellan gum, guar gum, gum arabic, locust bean gum, pectins, starches, and xanthan gum.

[0300] Example Ex43. An aerosol-generating article according to example Ex40 or Ex41 , wherein the aerosol-generating substrate has a total non-cellulose based thickening agent content of at least 1 percent by weight, for example at least 2 percent by weight, or at least 3 percent by weight, on a dry weight basis.

[0301] Example Ex44. An aerosol-generating article according to any preceding example, wherein the aerosol-generating substrate is in the form for one or more sheets.

[0302] Example Ex45. An aerosol-generating article according to example Ex44, wherein each of the one or more sheets of aerosol-generating substrate has a grammage of at least 130 grams per square metre.

[0303] Example Ex46. An aerosol-generating article according to example Ex44, wherein each of the one or more sheets of aerosol-generating substrate has an average thickness of less than or equal to 225 microns.

[0304] Example Ex47. An aerosol-generating article according to example Ex44, wherein each of the one or more sheets of aerosol-generating substrate has a density of at least 0.5 grams per cubic centimetre. Example Ex48. An aerosol-generating article according to any of examples Ex44 to Ex47, wherein the one or more sheets are gathered.

[0305] Example Ex49. An aerosol-generating article according to any of examples Ex44 to Ex48, wherein the one or more sheets are crimped.

[0306] Example Ex50. An aerosol-generating article according to any of examples Ex44 to Ex49, wherein the one or more sheets are in the form of cast leaf.

[0307] Example Ex51 . An aerosol-generating article according to any preceding example wherein the aerosol-generating substrate is provided within the cavity.

[0308] Example Ex52. An aerosol-generating article according to any of examples Ex1 to Ex50 wherein the cavity is substantially empty.

[0309] Example Ex53. An aerosol-generating article according to any preceding example, wherein one or more sheets of the aerosol-generating substrate are positioned between the frame and at least one of the first external surface and the second external surface.

[0310] Example Ex54. An aerosol-generating article according to any preceding example, wherein one or more sheets of the aerosol-generating substrate are positioned between the frame and an outer wrapper.

[0311] Example Ex55. An aerosol-generating article according to any preceding example, further comprising a first planar external layer defining the first planar external surface and a second planar external layer defining the second planar external surface.

[0312] Example Ex56. An aerosol-generating article according to example Ex55, wherein at least one of the first planar external layer and the second planar external layer comprise the aerosol-generating substrate.

[0313] Example Ex57. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article further comprises an outer wrapper, for example, an outer wrapper comprising the aerosol-generating substrate.

[0314] Example Ex58. An aerosol-generating article according to any preceding example, wherein a ratio of the width of the air outlet to the thickness of the air outlet is at least 3.5, for example at least 4.

[0315] Example Ex59. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article is substantially free from filtration material.

[0316] Example Ex60. An aerosol-generating article according to any preceding example, wherein the portion of the aerosol-generating article downstream of the cavity has a resistance to draw (RTD) of less than or equal to 25 mm H2O, for example less than or equal to 15 mm H2O, or less than or equal to 10 mm H2O, or less than or equal to 5 mm H2O.

[0317] Example Ex61. An aerosol-generating system comprising an aerosol-generating article according to any preceding example and an aerosol-generating device for use with the aerosolgenerating article to generate an inhalable aerosol, wherein the aerosol-generating device comprises a heater for heating the aerosol-generating substrate of the aerosol-generating article. Example Ex62. An aerosol-generating system according to example Ex61 , wherein the hater is configured to heat the aerosol-generating substrate to a maximum temperature of 250 degrees Celsius, for example, to a maximum temperature of 210 degrees Celsius.

[0318] Examples will now be further described with reference to the figures in which:

[0319] Figure 1 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0320] Figure 2 shows an exploded perspective view of the aerosol-generating article of Figure 1 ;

[0321] Figure 3 shows an exploded perspective view of an aerosol-generating article according to the present disclosure;

[0322] Figure 4 shows a perspective view of an aerosol-generating article according to the present disclosure;

[0323] Figure 5 shows a schematic cross-sectional view of an aerosol-generating device according to the present disclosure; and

[0324] Figure 6 shows a schematic cross-sectional view of the aerosol-generating device of Figure 5 in engagement with an aerosol-generating article of the present disclosure;

[0325] 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 both comprise a sheet of an aerosol-generating substrate as described herein. However, it will be understood that in some embodiments only one of the first planar external layer 24 and the second planar external layer 25 may comprise an aerosol-generating substrate. Alternatively, or additionally, the aerosol-generating substrate may be positioned elsewhere within the aerosol-generating article 10.

[0326] A suitable composition for the aerosol-generating substrate forming the first planar external layer 24 and the second planar external layer 25 is provided in Table A below.

[0327] Table A 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.

[0328] The aerosol-generating article 10 is substantially flat aerosol-generating article or substantially planar aerosol-generating article. In particular, the thickness of the aerosol-generating article 10 is less than 50 percent of both the length and the width of the aerosol-generating article. The aerosolgenerating 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, as discussed in more detail below in relation to Figure 2.

[0329] Figure 2 shows an exploded view of the aerosol-generating article 10 of Figure 1 .

[0330] 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. In this embodiment, the cavity 30 is substantially empty.

[0331] The frame 50 has a frame inner surface 52 extending in the z-direction or the transverse direction between the first planar external surface 21 and the second planar external surface 22. The frame inner surface 52 defines a cavity outer wall. The frame 50 has a frame outer surface 53 extending in the z-direction or the transverse direction between the first planar external surface 21 and the second planar external surface 22. The frame outer surface 53 at least partially defines one or more external surfaces of the aerosol-generating article, such as the front wall 13 and the back wall 14.

[0332] The frame 50 comprises a peripheral wall 51 that circumscribes the cavity 30. In more detail, the peripheral wall 51 is defined by the frame inner surface 52 and the frame outer surface 52. The peripheral wall 51 has a radial thickness, as measured between the frame inner surface 52 and the frame outer surface 53 in the x / y plane, of about 2 millimetres.

[0333] 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 defines at least a portion of the cavity 30. The second planar external layer 25 defines at least a portion of the cavity 30.

[0334] The aerosol-generating article 10 comprises an air inlet 11 and an air outlet 12. The air inlet 11 and the air outlet 12 are defined by, and extend through, the peripheral wall 51 of the frame 50. The air inlet 11 and the air outlet 12 each have a rectangular cross-section, a width of 2 millimetres, and a thickness of 0.9 millimetres. An airflow passage extends between the air inlet 11 and the air outlet 12 through the cavity 30. Figure 3 shows an exploded view of an aerosol-generating article 110 that is similar to the aerosol-generating article 10 of Figure 1 except that the first planar external layer 124 and the second planar external layer 125 do not comprise an aerosol-generating substrate. Instead, a sheet of aerosolgenerating substrate 140 is positioned within the cavity 30. A suitable composition for the aerosolgenerating substrate 140 is provided in Table A above.

[0335] As shown, the aerosol-generating substrate 140 fills the entire volume of the cavity 30. In the example of Figure 3, the aerosol-generating substrate 140 has a packing density of about 0.87, a density of about 0.3 grams per cubic centimetre, and a mass of about 110 milligrams. In another example, the aerosol-generating substrate 140 may have a different packing density, a different density and a different mass. For example, aerosol-generating substrate may have a packing density of 0.64, a density of 0.35 grams per cubic centimetre, and a mass of about 95 milligrams.

[0336] Figure 4 shows an aerosol-generating article 210 similar to the aerosol-generating article 10 of Figures 1 and 3 except that the aerosol-generating article 210 of Figure 4 comprises an outer wrapper 223 defining a first planar external surface 221 and a second planar external surface 222 instead of the first planar external layer 24 and the second planar external layer 25.

[0337] Figure 5 shows a schematic cross-sectional view of an aerosol-generating device 90 configured for use with an aerosol-generating article as described herein. The aerosol-generating article may be any of the aerosol-generating articles 10, 110, 210 as described herein with reference to the figures.

[0338] The aerosol-generating device 90 is an elongate aerosol-generating device extending between a proximal end 91 and a distal end 92. The aerosol-generating device 90 comprises a battery 93, a controller 94, a first heater 95 and a second heater 96 located within a housing 97. The controller 94 controls supply of power from the battery 93 to the first heater 95 and the second heater 96. A cavity 1000 is defined in the device 90, the cavity 1000 having an opening 1010 defined in the proximal end 91 of the device 90. The opening 1010 is rectangular in shape and is dimensioned to accommodate the transverse cross-section of the aerosol-generating article 410. The cavity 1000 comprises an upper planar surface 1020 and a lower planar surface 1030. The first heater 95 is located in the upper planar surface 1020 to heat the first planar external surface 21 of an aerosol-generating article inserted into the cavity 1000, and the second heater 96 is located in the lower planar surface 1030 to heat the second planar external surface 22 of an aerosol-generating article inserted into the cavity 1000. The device 90 comprises an air inlet 98 defining an air-flow path configured to allow air to flow into the cavity 1000 from outside the device.

[0339] Figure 7 shows a schematic cross-sectional view of the aerosol-generating device 90 of Figure 8 in engagement with an aerosol-generating article 410. The aerosol-generating article 410 may be any of the aerosol-generating articles 10, 110, 210 as described herein with reference to the figures.

[0340] There is little tolerance between the first planar external surface 21 and the second planar external surface 22 of the aerosol-generating article 410 and the internal surfaces 1020, 1030 of the cavity 1000. Thus, there is a snug fit between the aerosol-generating article 10 and the aerosolgenerating device 90. When a consumer has inserted the aerosol-generating article 410 into the cavity 1000, the device can be operated. The first heater 95 heats the first planar external surface 21 of the aerosol-generating article 410 and the second heater 96 heats the second planar external surface 22 of the aerosol-generating article, and as a result the aerosol-generating substrate is heated. Volatile components of the aerosol-generating substrate are evaporated and condense in the cavity 30 of the aerosol-generating article 410 to form an aerosol. The consumer inhales the aerosol by drawing on the end of the aerosol-generating article 410 comprising the air outlet 12. Once the aerosol-generating substrate has been depleted of volatile components, the aerosol-generating article 410 is removed from the cavity 1000 and disposed of.

[0341] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10% 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 . An aerosol-generating article for use with an aerosol-generating device to generate an inhalable aerosol, 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; one or more sheets of an aerosol-forming substrate comprising nicotine and one or more aerosol formers, wherein the total aerosol former content of the aerosol-forming substrate is at least 40 percent by weight on a dry weight basis; and an air inlet and an air outlet, and an airflow passage extending between the air inlet and the air outlet through the cavity.

2. An aerosol-generating article according to claim 1 , 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 two times the article thickness.

3. An aerosol-generating article according to claim 1 or 2, wherein the total aerosol former content of the aerosol-generating substrate is at least 50 percent by weight on a dry weight basis.

4. An aerosol-generating article according to any preceding claim, wherein the aerosolgenerating substrate has an exogenous nicotine content of at least 1 .5 percent by weight on a dry weight basis.

5. An aerosol-generating article according to any preceding claim, wherein the aerosolgenerating substrate is substantially free from tobacco.

6. An aerosol-generating article according to any preceding claim, wherein the aerosolgenerating substrate comprises one or more cellulose based agents.

7. An aerosol-generating article according to claim 6, wherein the total cellulose based agent content is at least 35 percent by weight on a dry weight basis.

8. An aerosol-generating article according to claim 6 or 7, wherein the aerosol-generating substrate comprises one or more cellulose based film forming agents selected from carboxymethyl cellulose (CMC), ethylcellulose (EC), hydroxyethyl cellulose (HEC), hydroxyethyl methylcellulose(HEMC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), and methylcellulose (MC).

9. An aerosol-generating article according to any preceding claim, wherein the aerosolgenerating substrate is provided in the cavity.

10. An aerosol-generating article according to any preceding claim, wherein the ratio of the width of the air outlet to the thickness of the air outlet is at least 4.

11. An aerosol-generating article according to any preceding claim, wherein the portion of the aerosol-generating article downstream of the cavity has an RTD of less than 25 mm H2O.

12. An aerosol-generating system comprising: an aerosol-generating article according to any preceding claim and an aerosol-generating device for use with the aerosol-generating article to generate an inhalable aerosol, wherein the aerosol-generating device comprises a heater for heating the aerosol-generating substrate of the aerosol-generating article.

13. An aerosol-generating system according to claim 12, wherein the heater is configured to heat the aerosol-generating substrate to a maximum temperature of 210 degrees Celsius.

Images