Aerosol-generating article comprising an expandable material

Abstract

An aerosol-generating article (200) for generating an inhalable aerosol, the aerosol-generating article (200) comprises an aerosol-generating body (102). The aerosol-generating body comprises an aerosol-generating substrate. The aerosol-generating article (200) further comprises an expansion body (103), the expansion body (103) comprises a dynamic material. The volume of the dynamic material is configured to vary depending on the moisture content of the dynamic material between a high moisture content state in which the dynamic material has a first volume, and a low moisture content state in which the dynamic material has a second volume. The second volume is greater than the first volume. The aerosol-generating body (102) and the expansion body (103) being arranged such that the pressure exerted on the aerosol-generating body (102) by the expansion body (103) is greater when the dynamic material is in the low moisture content state than when the dynamic material is in the high moisture content state.

Description

[0001] AEROSOL-GENERATING ARTICLE COMPRISING AN EXPANDABLE MATERIAL

[0002] The present invention relates to an aerosol-generating article for generating an inhalable aerosol. In particular, the present invention relates to an aerosol-generating article comprising an aerosol-generating body, the aerosol-generating body comprising an aerosolgenerating substrate. The aerosol-generating article further comprises an expansion body comprising dynamic material. The present invention also relates to an aerosol-generating system comprising the aerosol generating article and an aerosol-generating device.

[0003] Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than combusted, are known in the art. Typically, in such heated smoking articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0004] A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosolgenerating devices in which an aerosol is generated by the transfer of heat from one or more electrical heating elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosolgenerating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosol-generating substrate.

[0005] Use of an aerosol-generating article in combination with an external heating system is also known. For example, WO 2020 / 115151 describes the provision of one or more heating elements arranged around the periphery of the aerosol-generating article when the aerosolgenerating article is received in a cavity of the aerosol-generating device. As an alternative, inductively heatable aerosol-generating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosol-generating substrate have been proposed by WO 2015 / 176898.

[0006] In use, the aerosol-generating article comprising the aerosol-generating substrate is placed proximal to the heating element of an aerosol-generating device and the heating element is activated to heat the aerosol-generating substrate to generate an aerosol. However, it has been found that during use, the portion of aerosol-generating substrate closest to the heating element is heated first and reaches a higher temperature than portions of the aerosol-generating substrate located further from the heating element. As a result, the portions of aerosol-generating substrate located closer to the heating element become depleted early during the user experience. Portions of the aerosol-generating substrate located further from the heating element are heated by thermal transfer from the area closer to the heating element. However, these portions take longer to generate an aerosol since their heating is slower. This can result in an inconsistent user experience in which the early puffs contain a high concentration of aerosol generated from the substrate close to the heating element, but the later puffs contain a lower concentration of aerosol since this substrate is depleted.

[0007] In addition, to ensure the more distant portions of the aerosol-generating substrate reach a temperature suitable for aerosol generation, the heating element may need to reach a higher temperature. This may be inefficient and require a higher amount of power.

[0008] As a result, there is a need for an aerosol-generating article which provides a more consistent aerosol delivery over the duration of the use of the aerosol-generating article such that the aerosol delivery is more consistent. In addition, it would be desirable to provide a more consistent aerosol delivery without the need to use additional power.

[0009] According to a first aspect of the present disclosure, there is provided an aerosolgenerating article for generating an inhalable aerosol. The aerosol-generating article may comprise an aerosol-generating body. The aerosol-generating body may comprise an aerosol-generating substrate. The aerosol-generating article may comprise an expansion body. The expansion body may comprise a dynamic material. The volume of the dynamic material may be configured to vary depending on the moisture content of the dynamic material between a high moisture content state in which the dynamic material has a first volume, and a low moisture content state in which the dynamic material has a second volume. The second volume may be greater than the first volume. The aerosol-generating body and the expansion body may be arranged such that the pressure exerted on the aerosol-generating body by the expansion body is greater when the dynamic material is in the low moisture content state than when the dynamic material is in the high moisture content state.

[0010] According to a first aspect of the present invention, there is provided an aerosolgenerating article for generating an inhalable aerosol, the aerosol-generating article comprises an aerosol-generating body, the aerosol-generating body comprising an aerosol-generating substrate. The aerosol-generating article further comprises an expansion body. The expansion body comprises a dynamic material. The volume of the dynamic material is configured to vary depending on the moisture content of the dynamic material between a high moisture content state in which the dynamic material has a first volume, and a low moisture content state in which the dynamic material has a second volume, the second volume being greater than the first volume. The aerosol-generating body and the expansion body are arranged such that the pressure exerted on the aerosol-generating body by the expansion body is greater when the dynamic material is in the low moisture content state than when the dynamic material is in the high moisture content state.

[0011] In use the dynamic material may be initially provided in a high moisture content state such that the expansion body has a minimum volume and exerts a minimum pressure on the aerosol-generating body. When the aerosol-generating article is used in combination with an aerosol-generating device, at least the portion of the aerosol-generating article containing the aerosol-generating body is heated by a heating element. As the aerosol-generating article is heated, the portion of the aerosol-generating body nearest the heating element reaches a higher temperature first. As a result, the aerosol-generating substrate nearest the heating element will generate an aerosol first, and continue to do so until the aerosol-generating substrate is depleted. At the same time, the expansion body is also heated, either directly or by conduction from the aerosol-generating body. As the expansion body is heated, the moisture in the dynamic material evaporates causing the dynamic material to gradually transition from the high moisture content state to the low moisture content state. As it does this, the volume of the dynamic material, and the expansion body, increases. As the volume increases, the expansion body exerts an increasing pressure on the aerosol-generating body, compressing the aerosol-generating body. In doing so, the concentration of aerosolgenerating substrate increases in the aerosol-generating body, because the volume of the aerosol-generating body decreases. This increase in aerosol-generating substrate concentration in the aerosol-generating body over time may counteract the depletion of the aerosol-generating substrate near the heating element. This may advantageously maintain a substantially consistent aerosol delivery over the course of the use of the aerosol-generating article.

[0012] In addition, the aerosol-generating body and the expansion body may be arranged such that pressure is applied by the expansion body pushes the aerosol-generating substrate towards the heating element. This may mean that as the aerosol-generating substrate near the heating element becomes depleted, it is replaced by more aerosol-generating substrate which is pushed towards the heating element by the expansion body. This may further advantageously improve the consistency of the aerosol delivery.

[0013] As used herein with reference to the present invention, the term “aerosol-generating article” is used herein to denote an article wherein an aerosol-generating substrate is heated to produce and deliver an inhalable aerosol to a consumer. As used herein with reference to the present invention, the term “aerosol-generating substrate” denotes a substrate capable of releasing volatile compounds upon heating to generate an aerosol.

[0014] As used herein with reference to the present invention, the term “aerosol-generating device” refers to a device comprising a heater element that interacts with the aerosolgenerating substrate of the aerosol-generating article to generate an aerosol.

[0015] As used herein with reference to the present invention, the term “dynamic material” refers to a material in which at least one physical parameter, such as volume, varies in response to changes of at least one other property of the material, such as moisture content. Most materials shrink upon drying and swell upon wetting, a phenomenon known as dryshrinkage; and may be characterized by a dry-shrinkage coefficient either equal or greater than zero. However, the dynamic material of the present invention may have a negative dry shrinkage coefficient.

[0016] As used herein with reference to the present invention, the terms “high moisture content state” and “low moisture content state” are relative terms to describe a first state in which the dynamic material contains more moisture, and a second state in which the dynamic material contains less moisture. The dynamic material may have any absolute percentage moisture content in the high and low moisture content states, provided the dynamic material has a higher absolute percentage moisture in the high moisture content state than in the low moisture content state.

[0017] The high moisture content state may be a saturated state.

[0018] As used herein with reference to the present invention, the term “saturated state” refers to a state in which the moisture content of the dynamic material is at least 90 percent of the maximum possible moisture content of the dynamic material at 23 degrees Celsius, 101.3 kPa of air pressure, and 50 percent relative humidity. In the saturated state, the moisture content of the dynamic material may be at least 50 weight percent. For example, in the saturated state, the moisture content of the dynamic material may be at least 53 weight percent, at least 55 weight percent, or at least 57 weight percent.

[0019] The low moisture content may be a dry state.

[0020] As used herein with reference to the present invention, the term “dry state” refers to a state in which the moisture content of the dynamic material less than 20 percent relative to the dry weight of the dynamic material. In the dry state, the moisture content of the dynamic material may be no more than 2 weight percent. For example, in the dry state, the moisture content of the dynamic material may be no more than 1 weight percent. In the dry state, the moisture content of the dynamic material may be 0. The dry state may be achieved once the dynamic material has reached a specific temperature. For example, the dynamic material may be considered to have reached a dry state one it reaches a temperature of 230 degrees Celsius at atmospheric pressure.

[0021] The moisture content of the dynamic material may be configured to vary between a saturated state and a dry state.

[0022] The volume of the dynamic material is greater in its dry state than in its saturated state.

[0023] The volume of the dynamic material may be at least 1.5 times greater in its dry state than in its saturated state. For example, the volume of the dynamic material may be at least 2 times greater, at least 2.5 times greater, at least 3 times greater, at least 4 times greater, or at least 5 times greater in its dry state than in its saturated state.

[0024] A volume change of at least 1.5 times between the saturated state and the dry state may advantageously ensure a sufficient pressure is exerted on the aerosol-generating body by the expansion member to compress the aerosol-generating material.

[0025] The volume of the dynamic material may be no more than 10 times greater in its dry state than in its saturated state. For example, the volume of the dynamic material may be no more than 8 times greater, no more than 6 times greater, no more than 5 times greater, no more than 4 times greater, or no more than 3 times greater in its dry state than in its saturated state.

[0026] A volume change of no more than 10 times between the saturated state and the dry state may advantageously prevent the dynamic material from expanding so much that it damages the aerosol-generating article.

[0027] Preferably, the volume of the dynamic material may be between 3.5 and 4.25 greater in its dry state than in its saturated state.

[0028] The expansion body may be configured to exert any force on the aerosol-generating body when the dynamic material is in its dry state.

[0029] The expansion body may be configured to exert at least 0.3 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state. For example, the expansion body may be configured to exert at least 0.4 Newtons per square millimetre, or at least 0.5 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state.

[0030] Pressures in this range may advantageously ensure sufficient compression of the aerosol-generating substrate to provide a consistent user experience.

[0031] The expansion body may be configured to exert no more than 1.4 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state.

[0032] The expansion body may be configured to exert no more than 1 .2 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state. For example, the expansion body may be configured to exert no more than 1 Newton per square millimetre, or no more than 0.8 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state.

[0033] Pressures in this range may advantageously prevent damage to the aerosolgenerating article when the dynamic material is in its dry state.

[0034] The expansion body may be configured to exert between approximately 0.3 and 0.8 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state.

[0035] For example, the expansion body may be configured to exert between approximately 0.4 and 0.7 Newtons per square millimetre, or between approximately 0.5 and 0.6 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state.

[0036] The aerosol-generating body may be spaced apart from the expansion body. Where this is the case, the expansion body may not be in direct contact with the aerosol-generating body. The aerosol-generating article may comprise at least one intermediate body between the aerosol-generating body and the expansion body. The at least one intermediate body may be arranged to transfer the pressure from the expansion body to the aerosol-generating body.

[0037] The aerosol-generating body may be in direct contact with the expansion body. This arrangement may advantageously allow for direct transfer of pressure from the expansion body to the aerosol-generating body. In addition, this may allow for aerosol generated by the aerosol-generating substrate to pass into the expansion body. This may allow the aerosol to leave the aerosol-generating article.

[0038] The aerosol-generating body and the expansion body may be in the same segment of the aerosol-generating article. This may allow the aerosol-generating body to be in close proximity to the expansion body such that when the volume of the expansion body increases, pressure is instantly exerted on the aerosol-generating body. This may efficiently compress the aerosol-generating body to increase the concentration of aerosol-generating substrate near the heating element of the aerosol-generating article to advantageously provide a consistent aerosol delivery.

[0039] The segment containing the aerosol-generating body and the expansion body may be referred to as the aerosol-generating segment.

[0040] The aerosol-generating body and the expansion body may have any length.

[0041] At least one of the aerosol-generating body and the expansion body may have a length of at least 6 millimetres, at least 9 millimetres, or at least 15 millimetres.

[0042] At least one of the aerosol-generating body and the expansion body may have a length of no more than 50 millimetres, no more than 40 millimetres, or no more than 30 millimetres. At least one of the aerosol-generating body and the expansion body may have a length of between about 6 millimetres and about 50 millimetres, between about 9 millimetres and about 40 millimetres, or between about 15 millimetres and about 30 millimetres.

[0043] The aerosol-generating body and the expansion body may have different lengths. The aerosol-generating body and the expansion body may have the same length.

[0044] An aerosol-generating article in which the aerosol-generating body and the expansion body have the same length may advantageously allow the aerosol-generating body to be compressed along its full length by the expansion body. As described above, this may advantageously provide a more consistent aerosol delivery.

[0045] As used herein with reference to the present invention, the term “length” refers to the dimension of a component of the aerosol-generating article in the longitudinal direction. For example, it may be used to denote the dimension of the aerosol-generating body or of the expansion body in the longitudinal direction.

[0046] As used herein with reference to the present invention, the term “longitudinal” refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article or aerosol-generating device, which extends between the upstream and downstream ends of the aerosol-generating article or aerosol-generating device. As used herein, the terms “upstream” and “downstream” describe the relative positions of elements, or portions of elements, of the aerosol-generating article or aerosol-generating device in relation to the direction in which the aerosol is transported through the aerosol-generating article or aerosol-generating device during use.

[0047] The upstream end of the aerosol-generating body may be aligned with the upstream end of the expansion body. The downstream end of the aerosol-generating body may be aligned with the downstream end of the expansion body.

[0048] This arrangement may allow the aerosol-generating body to be compressed along its full length by the expansion body. As described above, this may advantageously provide a more consistent aerosol delivery.

[0049] The aerosol-generating body may circumscribe the expansion body such that the aerosol-generating body is located radially outside the expansion body.

[0050] In this arrangement, the aerosol-generating body may have an annular cross sectional shape with the expansion body located in the centre of the aerosol-generating body. The expansion body may have a cylindrical shape. The shape and size of the expansion body may correspond to the shape and size of an opening in the centre of the aerosol-generating body. The expansion body may be aligned with the central axis of the aerosol-generating body. As used herein with reference to the present invention, the terms “radial” and “transverse” refer to the direction that is perpendicular to the longitudinal axis. The term “cross-section” of the aerosol-generating article or a component of the aerosol-generating article refers to the transverse cross-section.

[0051] This arrangement may mean that when the dynamic material transitions from the high moisture content state to the low moisture content state, the expansion of the dynamic material exerts a force outwards from the central axis of the aerosol-generating article in all radial direction. This may compress the aerosol-generating material towards the outer surface of the aerosol-generating article. This arrangement may be particularly advantageous where the aerosol-generating device to be used with the aerosol-generating article includes an external heating element. In this arrangement, the aerosol-generating device may include a heating chamber into which the aerosol-generating article is inserted. The aerosol-generating device includes a heating element disposed around the heating chamber such that they heat the outer surface of the aerosol-generating article first when they are activated. As a result, the portion of the aerosol-generating substrate which is closest to the radially outer surface of the aerosolgenerating article is heated first and reaches a higher temperature. This means that this portion of aerosol-generating substrate becomes depleted first. As the expansion body dries, it expands, exerting pressure in a radial direction on the aerosol-generating body, pushing aerosol-generating substrate to the radial outer surface of the aerosol-generating article into the portion of the aerosol-generating article which is heated to replenish the depleted aerosolgenerating substrate. In this way, the aerosol delivery of the aerosol-generating article may be more consistent over the course of the use of the aerosol-generating article.

[0052] The ratio of the volume of the aerosol-generating body to the volume of the expansion body when the dynamic material is in its saturated state may be at least 1.

[0053] For example, the ratio of the volume of the aerosol-generating body to the volume of the expansion body when the dynamic material is in its saturated state may be at least 2, at least 2.5, or at least 3.

[0054] The ratio of the volume of the ratio of the volume of the aerosol-generating body to the volume of the expansion body when the dynamic material is in its saturated state may be no mote than 6. For example, the ratio of the volume of the aerosol-generating body to the volume of the expansion body when the dynamic material is in its saturated state may be no more than 5, no more than 4, or no more than 3.

[0055] The ratio of the volume of the ratio of the volume of the aerosol-generating body to the volume of the expansion body when the dynamic material is in its saturated state may be about 3. It has been found that this ratio of the volume of the aerosol-generating body to the volume of the expansion body may advantageously provide sufficient volume expansion to improve the consistency of aerosol delivery over the duration of the user experience of the aerosol-generating article.

[0056] The expansion body may circumscribe the aerosol-generating body such that the expansion body is located radially outside the aerosol-generating body.

[0057] In this arrangement, the expansion body may have an annular cross sectional shape with the aerosol-generating body located in the centre of the aerosol-generating body. The aerosol-generating body may have a cylindrical shape. The shape and size of the aerosolgenerating body may correspond to the shape and size of an opening in the centre of the expansion body. The aerosol-generating body may be aligned with the central axis of the expansion body.

[0058] This arrangement may mean that when the dynamic material transitions from the high moisture content state to the low moisture content state, the expansion of the dynamic material exerts a force inwards from the radial outer surface of the aerosol-generating article towards the centre of the aerosol-generating article. This may compress the aerosol-generating material towards the centre of the aerosol-generating article. This arrangement may be particularly advantageous where the aerosol-generating device to be used with the aerosolgenerating article includes an internal heating element, such as a blade heater or a pin heater. In this arrangement, the aerosol-generating device may include a heating chamber into which the aerosol-generating article is inserted. The aerosol-generating device includes a heating element extending into the heating chamber which is inserted into the centre of the aerosolgenerating substrate such that the inner portion of the aerosol-generating article is heated first when they are activated. As a result, the portion of the aerosol-generating substrate which is closest to the centre of the aerosol-generating article is heated first and reaches a higher temperature. This means that this portion of aerosol-generating substrate becomes depleted first. As the expansion body dries, it expands, exerting pressure in a radial direction on the aerosol-generating body, pushing aerosol-generating substrate to the radial centre of the aerosol-generating article into the portion of the aerosol-generating article which is heated to replenish the depleted aerosol-generating substrate. In this way, the aerosol delivery of the aerosol-generating article may be more consistent over the course of the use of the aerosolgenerating article.

[0059] The expansion body may be porous. The provision of a porous expansion body may allow the dynamic material to retain moisture when the dynamic material is in the high moisture content state. In addition, the provision of a porous expansion body may advantageously allow aerosol generated by the aerosol-generating substrate to pass into the expansion body and pass out of the aerosol-generating article.

[0060] Any liquid may be used in combination with the dynamic material to vary the moisture content of the dynamic material. For example, water may be used to increase the moisture content of the dynamic material in the high moisture content state. In this example, the expansion body may comprise water absorbed in the dynamic material.

[0061] In use, the aerosol-generating article may be provided with an expansion body comprising a dynamic material comprising water absorbed in the dynamic material. In this way, the dynamic material may be provided in the high moisture content state. The high moisture content state may be a saturated state.

[0062] When the aerosol-generating article is used in combination with an aerosol-generating device, the dynamic material is heated by the heating element. This heats and vaporizes the water. The water vapour passes out of the aerosol-generating device along with the aerosol from the aerosol-generating substrate.

[0063] The provision of water in the dynamic material may be particularly suitable since it is flavourless and therefore does not interfere with the flavour of the aerosol generated by the aerosol-generating substrate. In addition, water vapor in combination with the aerosol may improve the mouth feel of the aerosol delivered to a user.

[0064] Alternatively, or in addition, an aerosol former may be used to increase the moisture content of the dynamic material in the high moisture content state. In this example, the expansion body may comprise an aerosol former absorbed in the dynamic material.

[0065] In use, the aerosol-generating article may be provided with an expansion body comprising a dynamic material comprising an aerosol former absorbed in the dynamic material. In this way, the dynamic material may be provided in the high moisture content state. The high moisture content state may be a saturated state.

[0066] When the aerosol-generating article is used in combination with an aerosol-generating device, the dynamic material is heated by the heating element. The heated aerosol former generates an aerosol. The aerosol from the dynamic material may pass out of the aerosolgenerating device along with the aerosol from the aerosol-generating substrate.

[0067] Suitable aerosol formers for inclusion in the dynamic 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.

[0068] Preferably, the dynamic material comprises glycerol as an aerosol former. The dynamic material may comprise an aerosol-generating substrate. For example, the dynamic material may comprise a liquid aerosol-generating substrate or a gel aerosolgenerating substrate.

[0069] The dynamic material may comprise any amount of aerosol former. The aerosol former content of the dynamic material may be 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] The aerosol former content of the dynamic material may be no more than 50 percent by weight, no more than 30 percent by weight, or no more than 25 percent by weight, on a dry weight basis.

[0071] The aerosol former content of the dynamic material may be between about 5 percent by weight and about 50 percent by weight, between about 10 percent by weight and about 25 percent by weight, or between about 15 percent by weight and about 25 percent by weight, on a dry weight basis.

[0072] The aerosol former content of the dynamic material may be about 20 percent by weight, on a dry weight basis.

[0073] The dynamic material may comprise a hydrophobic material.

[0074] The dynamic material may comprise at least one of a fibrous material or a crimped material. The dynamic material may comprise hydrophobic fibres. The dynamic material may comprise a material having a contact angle of greater than 150 degrees. The dynamic material may comprise hydrophobic cellulose. The dynamic material may comprise superhydrophobic cellulose.

[0075] As used herein with reference to the present invention, the term “hydrophobic cellulose” refers to a cellulosic material that has undergone a chemical or physical treatment to make the surface of the cellulose hydrophobic such that it repels water. For example, this can be achieved by coating the fibres of the cellulosic material with low surface energy materials such as hydrocarbon or fluorine containing compounds. However, any suitable means of achieving hydrophobicity may be used.

[0076] Advantageously, hydrophobic cellulose is a material that exhibits dry expansion and is characterised by having a negative dry-shrinkage coefficient. It has been surprisingly found that a dynamic material comprising hydrophobic cellulose can, upon drying, exert sufficient pressure on the aerosol-generating body to improve the consistency of the aerosol delivery of the aerosol-generating article.

[0077] The resistance to draw of the aerosol-generating article may remain substantially constant as the dynamic material transitions from the high moisture content state to the low moisture content state. The resistance to draw of the aerosol-generating article may remain substantially constant as the dynamic material transitions from its saturated state to its dry state. The resistance to draw of the aerosol-generating article when the dynamic material is in its saturated state may be substantially the same as the resistance to draw of the aerosolgenerating article when the dynamic material is in its dry state.

[0078] For example, the resistance to draw of the aerosol-generating article when the dynamic material is in its dry state may be within 20 percent, within 15 percent, within 10 percent, or within 5 percent of the resistance to draw of the aerosol-generating article when the dynamic material is in its saturated state.

[0079] The resistance to draw of a component or the aerosol-generating article is measured in accordance with ISO 6565-2015. The resistance to draw refers the pressure required to force air through the full length of a component.

[0080] The provision of a substantially constant resistance to draw despite the dynamic material transitioning from the high moisture content state to the low moisture content state may advantageously ensure a consistent user experience over the duration of the use of the aerosol-generating article.

[0081] Where both the aerosol-generating body and the expansion body are porous, as the dynamic material expands the porosity of the expansion body may increase. At the same time, pressure exerted on the aerosol-generating body by the expansion body will compress the aerosol-generating material reducing the pore size and porosity of the aerosol-generating body. The increase in porosity of the expansion body and the decrease in porosity of the aerosol-generating body may balance each other out resulting in a substantially constant total porosity for the expansion body and the aerosol-generating body. This may advantageously maintain the resistance to draw of the aerosol-generating article at a constant level.

[0082] The total resistance to draw (RTD) of the aerosol-generating body and the expansion body when they are arranged in the aerosol-generating article may be referred to as the RTD of the aerosol-generating segment.

[0083] The RTD of the aerosol-generating segment may be at least 1 millimetre H2O. For example, the RTD of the aerosol-generating segment may be at least 2 millimetres H2O, at least 3 millimetres H2O, at least 4 millimetres H2O, at least 5 millimetres H2O, at least 6 millimetres H2O, at least 7 millimetres H2O, at least 8 millimetres H2O, at least 9 millimetres H2O, at least 10 millimetres H2O, at least 15 millimetres H2O, at least 20 millimetres H2O, at least 30 millimetres H2O, at least 40 millimetres H2O, at least 50 millimetres H2O, or at least 70 millimetres H2O.

[0084] The RTD of the aerosol-generating segment may be no more than 400 millimetres H2O. For example, the overall RTD of the aerosol-generating article may be no more than 350 millimetres H2O, no more than 300 millimetres H2O, no more than 220 millimetres H2O, or no more than 140 millimetres H2O.

[0085] The RTD of the aerosol-generating segment may be between 1 millimetre H2O and 400 millimetres H2O. For example, the overall RTD of the aerosol-generating article may be between 5 millimetres H2O and 350 millimetres H2O, between 10 millimetres H2O and 300 millimetres H2O, between 20 millimetres H2O and 250 millimetres H2O, between 50 millimetres H2O and 220 millimetres H2O, or between 70 millimetres H2O and 140 millimetres H2O.

[0086] The aerosol-generating body comprises an aerosol-generating substrate. The aerosol-generating substrate may comprise any aerosol-generating material. The aerosolgenerating substrate may comprise tobacco.

[0087] The aerosol-generating substrate may comprise shredded tobacco material. For example, the shredded tobacco material may be in the form of cut filler. Alternatively, the shredded tobacco material may be in the form of a shredded sheet of homogenised tobacco material. For example, the aerosol-generating substrate may comprise cast leaf tobacco material.

[0088] The aerosol-generating substrate may comprise at least one other material. For example, the aerosol-generating substrate may comprise at least one botanical. Suitable botanicals include but are not limited to chamomile, verbena, tea leaf, cloves, and mint.

[0089] The aerosol-generating substrate may comprise at least one aerosol-former.

[0090] Suitable aerosol-formers include but are not limited to monohydric alcohols, such as menthol; 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.

[0091] The aerosol-generating article may further comprise a wrapper circumscribing the aerosol-generating body and the expansion body.

[0092] The provision of a wrapper may advantageously hold the aerosol-generating body in close proximity to the expansion body. In addition, the wrapper may extend beyond the downstream end of the aerosol-generating body and the expansion body to enable the aerosol-generating segment to be connected to other elements of the aerosol-generating article.

[0093] The provision of a wrapper may also advantageously retain the shape of the aerosolgenerating article when the dynamic material transitions from the high moisture content state to the low moisture content. The wrapper may comprise any suitable material. For example, the wrapper may comprise at least one of cigarette paper, metal foil, and a polymer material. The wrapper may comprise a seam line to close the wrapper. The seam line may be joined using a starch glue.

[0094] The aerosol-generating article may have any diameter. For example, the aerosolgenerating article may have a diameter of between about 3 millimetres and about 10 millimetres, between about 4 millimetres and about 9 millimetres, or between about 4 and about 7 millimetres.

[0095] The aerosol-generating segment may have a diameter which is substantially the same as the aerosol-generating article.

[0096] The aerosol-generating article any length. For example, the aerosol-generating segment may have a length of between about 40 millimetres and about 100 millimetres, between about 50 millimetres and about 90 millimetres, or between about 60 millimetres and about 80 millimetres.

[0097] The aerosol-generating article may have any cross sectional shape. The aerosolgenerating article may have a circular or ovular cross sectional shape. The aerosol-generating article may have a rectangular, square, triangular, or some other polygonal cross sectional shape.

[0098] The aerosol-generating article may further comprise a hollow tubular element. The hollow tubular element may be disposed downstream of the aerosol-generating segment. The hollow tubular element may be disposed immediately downstream of the aerosol-generating segment.

[0099] As used herein with reference to the present disclosure, the term "hollow tubular element" denotes a generally elongate element defining a lumen or airflow passage along a longitudinal axis thereof. In particular, the term "tubular" will be used in the following with reference to a tubular element having a substantially cylindrical cross-section and defining at least one airflow conduit establishing an uninterrupted fluid communication between an upstream end of the tubular element and a downstream end of the tubular element. However, it will be understood that alternative geometries (for example, alternative cross-sectional shapes) of the tubular element may be possible.

[0100] In the context of the present invention, a hollow tubular element provides an unrestricted flow channel. This means that the hollow tubular element provides a negligible level of resistance to draw (RTD). The term “negligible level of RTD” is used to describe an RTD of less than 1 millimetres H2O per 10 millimetres of length of the hollow tubular element, preferably less than 0.4 millimetres H2O per 10 millimetres of length of the hollow tubular element, more preferably less than 0.1 millimetres H2O per 10 millimetres of length of the hollow tubular element. The RTD of a hollow tubular element is preferably less than or equal to 10 millimetres H2O. More preferably, the RTD of a hollow tubular element is less than or equal to 5 millimetres H2O. Even more preferably, the RTD of a hollow tubular element is less than or equal to 2.5 millimetres H2O. Even more preferably, the RTD of the hollow tubular element is less than or equal to 2 millimetres H2O. Even more preferably, the RTD of the hollow tubular element is less than or equal to 1 millimetre H2O.

[0101] The RTD of a hollow tubular element may be at least 0 millimetres H2O, or at least 0.25 millimetres H2O or at least 0.5 millimetres H2O or at least 1 millimetre H2O.

[0102] As will be described in greater detail within the present disclosure, the aerosolgenerating article may comprise a ventilation zone at a location along the hollow tubular element. Such, or any, ventilation zone may extend through the peripheral wall of the hollow tubular element. As such, fluid communication is established between the flow channel internally defined by the hollow tubular element and the outer environment. The ventilation zone is further described within the present disclosure.

[0103] Preferably, the length of the hollow tubular element is at least 15 millimetres. More preferably, the length of the hollow tubular element is at least 20 millimetres. The length of the hollow tubular element may be at least 25 millimetres. More preferably, the length of the hollow tubular element is at least 30 millimetres.

[0104] The length of the hollow tubular element is preferably less than 50 millimetres. More preferably, the length of the hollow tubular element is less than 45 millimetres. More preferably, the length of the hollow tubular element is less than 40 millimetres.

[0105] A relatively long hollow tubular element provides and defines a relatively long internal cavity within the aerosol-generating article. As discussed in the present disclosure, providing an empty cavity downstream (preferably, immediately downstream) of the aerosol-generating segment enhances the nucleation of aerosol particles generated by the substrate. Providing a relatively long cavity maximises such nucleation benefits, thereby improving aerosol formation and cooling.

[0106] The wall thickness of the hollow tubular element may preferably be 250 micrometres (0.25 millimetres).

[0107] The hollow tubular element preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating segments and to the external diameter of the aerosol-generating article.

[0108] The hollow tubular element may have an internal diameter of between 2 millimetres and 10 millimetres, between 3 millimetres and 9 millimetres, between 4 millimetres and 8 millimetres, or between 5 millimetres and 7 millimetres. The hollow tubular element may comprise a paper-based material. The hollow tubular element may comprise at least one layer of paper. The paper may be very rigid paper. The paper may be crimped paper, such as crimped heat resistant paper or crimped parchment paper.

[0109] Preferably, the hollow tubular element may comprise cardboard. The hollow tubular element may be a cardboard tube. The hollow tubular element may be formed from cardboard.

[0110] The hollow tubular element may comprise a polymeric material. For example, the hollow tubular element may comprise a polymeric film. The polymeric film may comprise a cellulosic film. The hollow tubular element may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibres. The hollow tube may comprise cellulose acetate tow.

[0111] In some embodiments, the aerosol-generating article according to the present invention may comprise a ventilation zone at a location along the hollow tubular element.

[0112] As such, a ventilated cavity is provided downstream of the aerosol-generating segment. This provides several potential technical benefits.

[0113] First of all, the inventors have found that one such ventilated hollow tubular element provides a particularly efficient cooling of the aerosol. Thus, a satisfactory cooling of the aerosol can be achieved.

[0114] Secondly, the inventors have surprisingly found that such rapid cooling of the volatile species released upon heating the aerosol-generating substrate promotes enhances nucleation of aerosol particles.

[0115] The ventilation zone may typically comprise a plurality of perforations through the peripheral wall of the hollow tubular element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. In some embodiments, the ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed online during manufacturing of the aerosol-generating article. Preferably, each circumferential row of perforations comprises from 8 to 30 perforations.

[0116] An aerosol-generating article in accordance with the present invention may have a ventilation level of at least 25 percent.

[0117] The term “ventilation level” is used throughout the present specification to denote a volume ratio between of the airflow admitted into the aerosol-generating article via the ventilation zone (ventilation airflow) and the sum of the aerosol airflow and the ventilation airflow. The greater the ventilation level, the higher the dilution of the aerosol flow delivered to the consumer. The aerosol-generating article preferably has a ventilation level of at least 25 percent, more preferably at least 30 percent, even more preferably at least 40 percent, even more preferably at least 50 percent. An aerosol-generating article in accordance with the present invention may have a ventilation level of up to 90 percent. Preferably, an aerosol-generating article in accordance with the present invention has a ventilation level of less than or equal to 80 percent, more preferably less than or equal to 70 percent, even more preferably less than or equal to 60 percent.

[0118] The aerosol-generating article may further comprise a downstream filter segment. The downstream filter segment may be located at the downstream end of the aerosol-generating article. The downstream end of the downstream filter segment may define the downstream end of the aerosol-generating article.

[0119] The downstream filter segment may be located downstream of a hollow tubular element, which is described above.

[0120] The downstream filter segment is preferably a solid plug, which may also be described as a ‘plain’ plug and is non-tubular. The filter segment therefore preferably has a substantially uniform transverse cross section.

[0121] The downstream filter segment is preferably formed of a fibrous filtration material. The fibrous filtration material may be for filtering the aerosol that is generated from the aerosolgenerating substrate. Suitable fibrous filtration materials would be known to the skilled person. Particularly preferably, the at least one downstream filter segment comprises a cellulose acetate filter segment formed of cellulose acetate tow.

[0122] Preferably, the downstream filter segment has a low particulate filtration efficiency.

[0123] According to a second aspect of the present disclosure, there is provided an aerosolgenerating article for generating an inhalable aerosol. The aerosol-generating article may comprise an aerosol-generating body. The aerosol-generating body may comprise an aerosol-generating substrate. The aerosol-generating article may comprise an expansion body. The expansion body may comprise a hydrophobic material.

[0124] According to a first aspect of the present invention, there is provided an aerosolgenerating article for generating an inhalable aerosol. The aerosol-generating article comprises an aerosol-generating body. The aerosol-generating body comprises an aerosolgenerating substrate. The aerosol-generating article comprises an expansion body. The expansion body comprises a hydrophobic material.

[0125] According to a third aspect of the present disclosure, there is provided an aerosolgenerating system for generating an inhalable aerosol. The system may comprise an aerosolgenerating article according to the first or second aspects of the invention. The aerosolgenerating system may comprise an aerosol-generating device. The aerosol-generating device may comprise a heating chamber for receiving the aerosol-generating article. The aerosol-generating device may comprise a heating element provided in the heating chamber or about the periphery of the heating chamber.

[0126] Where the heating element is provided in the heating chamber, the heating element may be in the form of a blade or a pin extending from the upstream end of the heating chamber. When the aerosol generating article is inserted into the heating chamber, the heating element may be inserted into the centre of the aerosol generating article. An aerosol-generating device of this type may be used in combination with an aerosol-generating article in which the aerosolgenerating body is provided along the longitudinal centre of the article and the expansion body circumscribes the aerosol-generating body. In this way, the heating element may be inserted directly into the aerosol-generating body. In addition, when the dynamic material transitions from the high moisture content state to the low moisture content state, the expanding dynamic material may push the aerosol-generating substrate towards the heating element.

[0127] Where the heating element is provided about the periphery of the heating chamber, the heating element may be in the form of an external heating element. An aerosol-generating device of this type may be used in combination with an aerosol-generating article in which the expansion body is provided along the longitudinal centre of the article and the aerosolgenerating body circumscribes the expansion body. In this way, the aerosol-generating body located close to the heating element. In addition, when the dynamic material transitions from the high moisture content state to the low moisture content state, the expanding dynamic material may push the aerosol-generating substrate towards the heating element.

[0128] A diameter of the heating chamber may be substantially the same as or greater than a diameter of the aerosol-generating article. A diameter of the heating chamber may be the same as a diameter of the aerosol-generating article in order to establish a tight fit with the aerosol-generating article.

[0129] 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.

[0130] Example 1. An aerosol-generating article for generating an inhalable aerosol, the aerosol-generating article comprising: an aerosol-generating body, the aerosol-generating body comprising an aerosol-generating substrate, and an expansion body, the expansion body comprising a dynamic material, the volume of the dynamic material being configured to vary depending on the moisture content of the dynamic material between a high moisture content state in which the dynamic material has a first volume, and a low moisture content state in which the dynamic material has a second volume, the second volume being greater than the first volume, the aerosol-generating body and the expansion body being arranged such that the pressure exerted on the aerosol-generating body by the expansion body is greater when the dynamic material is in the low moisture content state than when the dynamic material is in the high moisture content state.

[0131] Example 2. An aerosol-generating article according to Example 1 , wherein the moisture content of the dynamic material is configured to vary between a saturated state and a dry state.

[0132] Example 3. An aerosol-generating article according to Example 2, wherein the volume of the dynamic material is configured to be at least 3 times greater in its dry state than in its saturated state.

[0133] Example 4. An aerosol-generating article according to Example 2 or Example 3, wherein the expansion body is configured to exert between approximately 0.3 and 0.8 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state.

[0134] Example 5. An aerosol-generating article according to any preceding Example, wherein the aerosol-generating body is in direct contact with the expansion body.

[0135] Example 6. An aerosol-generating article according to any preceding Example, wherein the aerosol-generating body and the expansion body are in the same segment of the aerosol-generating article.

[0136] Example 7. An aerosol-generating article according to any preceding Example, wherein the length of at least one of the aerosol-generating body and the expansion body is between about 6 millimetres and about 50 millimetres.

[0137] Example 8. An aerosol-generating article according to any preceding Example, wherein the aerosol-generating body and the expansion body have the same length.

[0138] Example 9. An aerosol-generating article according to any preceding Example, wherein the upstream end of the aerosol-generating body is aligned with the upstream end of the expansion body, and the downstream end of the aerosol-generating body is aligned with the downstream end of the expansion body.

[0139] Example 10. An aerosol-generating article according to any preceding Example, wherein the aerosol-generating body circumscribes the expansion body such that the aerosolgenerating body is located radially outside the expansion body.

[0140] Example 11. An aerosol-generating article according to any one of Examples 2 to 4, wherein the ratio of the volume of the aerosol-generating body to the volume of the expansion body when the dynamic material is in its saturated state is at least 3.

[0141] Example 12. An aerosol-generating article according to any one of Examples 1 to 9, wherein the expansion body circumscribes the aerosol-generating body such that the expansion body is located radially outside the aerosol-generating body. Example 13. An aerosol-generating article according to any preceding Example, wherein the expansion body is porous.

[0142] Example 14. An aerosol-generating article according to any preceding Example, wherein the expansion body comprises water absorbed in the dynamic material.

[0143] Example 15. An aerosol-generating article according to any preceding Example, wherein the expansion body comprises an aerosol former absorbed in the dynamic material.

[0144] Example 16. An aerosol-generating article according to Example 15, wherein the aerosol former content of the dynamic material is about 20 percent by weight, on a dry weight basis.

[0145] Example 17. An aerosol-generating article according to any preceding Example, wherein the dynamic material comprises a hydrophobic material.

[0146] Example 18. An aerosol-generating article according to any preceding Example, wherein the dynamic material comprises at least one of a fibrous material and a crimped material.

[0147] Example 19. An aerosol-generating article according to any preceding Example, wherein the dynamic material comprises a hydrophobic cellulose material.

[0148] Example 20. An aerosol-generating article according to any one of Examples 2 to 4, wherein the resistance to draw of the aerosol-generating article when the dynamic material is in its dry state is within 5 percent of the resistance to draw of the aerosol-generating article when the dynamic material is in its saturated state.

[0149] Example 21. An aerosol-generating article according to any preceding Example, having a resistance to draw of between about 50 and 220 mm H2O.

[0150] Example 22. An aerosol-generating article according to any preceding Example, wherein the aerosol-generating substrate comprises tobacco.

[0151] Example 23. An aerosol-generating article according to any preceding Example, wherein the aerosol-generating substrate comprises at least one aerosol-former.

[0152] Example 24. An aerosol-generating article according to any preceding Example, further comprising a wrapper circumscribing the aerosol-generating body and the expansion body.

[0153] Example 25. An aerosol-generating article for generating an inhalable aerosol, the aerosol-generating article comprising: an aerosol-generating body, the aerosol-generating body comprising an aerosol-generating substrate, and an expansion body, the expansion body comprising a hydrophobic material.

[0154] Example 26. An aerosol-generating article according to Example 25, wherein the expansion body comprises a hydrophobic cellulose material. Example 27. An aerosol-generating system for generating an inhalable aerosol, the system comprising, an aerosol-generating article according to any preceding Example, and an aerosol-generating device comprising a heating chamber for receiving the aerosolgenerating article and a heating element provided in the heating chamber or about the periphery of the heating chamber.

[0155] In the following, the invention will be further described with reference to the drawings of the accompanying Figures, in which:

[0156] Figure 1 is a perspective view of an aerosol-generating article according to the present invention;

[0157] Figure 2 is a cross sectional view of an aerosol-generating article according to the present invention;

[0158] Figure 3a is a perspective view of an aerosol-generating article according to the present invention when the dynamic material is in the high moisture content state;

[0159] Figure 3b is a perspective view of an aerosol-generating article according to the present invention when the dynamic material is in the low moisture content state; and

[0160] Figure 4 is a cross sectional view of an aerosol-generating system according to the present invention.

[0161] The aerosol-generating article in Figure 1 comprises an aerosol-generating body 102, an expansion body 103, and a wrapper 101. Consequently, the aerosol-generating article of Figure 1 may also be considered an aerosol-generating segment 100.

[0162] The aerosol-generating body 102 comprises an aerosol-generating substrate. The aerosol-generating substrate comprises cast leaf tobacco material. The aerosol-generating substrate comprises glycerine as an aerosol former.

[0163] The expansion body 103 comprises a dynamic material. The dynamic material comprises fibrous hydrophobic cellulose material. The volume of the dynamic material varies between a high moisture content state and a low moisture content state. The volume of the dynamic material is configured to be at least 3 times greater in a dry state than in a saturated state.

[0164] The expansion body 103 is provided as a cylindrical portion of dynamic material, the diameter of the expansion body 103 being less than the diameter of the aerosol-generating segment. The aerosol-generating body 102 is provided as a cylindrical portion of aerosolgenerating material having a larger diameter than the expansion body 103. The aerosolgenerating body 102 includes an opening along its central longitudinal axis. The expansion body 103 is provided in the opening such that the aerosol-generating body 102 circumscribes the expansion body 103 along the full length of the expansion body 103. The aerosolgenerating body 102 and the expansion body 103 both have a length of about 20 millimetres and the upstream end of the aerosol-generating body 102 is aligned with the upstream end of the expansion body 103.

[0165] The aerosol-generating segment 100 further comprises a wrapper 101. The wrapper 101 comprises cigarette paper and circumscribes both the aerosol-generating body 102 and the expansion body 103. The wrapper 101 is secured in place using a starch glue provided along a longitudinal seam line (not shown).

[0166] Figure 2 shows a second aerosol-generating article 200 according to the present invention. The aerosol-generating article 200 comprises an aerosol-generating segment 100 located at the upstream end of the aerosol-generating article 200. The aerosol-generating segment 100 is the same as the segment 100 described above in relation to Figure 1. The aerosol-generating article 200 further comprises a hollow tubular element 201 disposed immediately downstream of, and longitudinally aligned with the aerosol-generating segment 100. The hollow tubular element 201 defines a hollow section of the aerosol-generating article 200. The hollow tubular element 201 does not substantially contribute to the overall RTD of the aerosol-generating article 200. In more detail, an RTD of the hollow tubular element 201 is about 0 millimetres H2O.

[0167] The hollow tubular element 201 is provided in the form of a hollow cylindrical tube made of cardboard. The hollow tubular element 201 defines an internal cavity that extends all the way from an upstream end of the hollow tubular element 201 to a downstream end of the hollow tubular element 201. The internal cavity is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity.

[0168] The aerosol-generating article 200 comprises a ventilation zone 203 provided at a location along the hollow tubular element 201. The ventilation zone 203 comprises a circumferential row of openings or perforations circumscribing the hollow tubular element 201. The perforations of the ventilation zone 203 extend through the wall of the hollow tubular element 201 , in order to allow fluid ingress into the internal cavity from the exterior of the article 200. A ventilation level of the aerosol-generating article 200 is about 40 percent.

[0169] The aerosol-generating article 200 further comprises a downstream filter segment 202. The downstream filter segment 202 extends from the downstream end of the hollow tubular element 201 to the downstream end of the aerosol-generating article 200. The downstream filter segment 202 has a length of about 7 millimetres. An external diameter of the downstream filter segment 202 is about 7.2 millimetres. The downstream filter segment 202 comprises a low-density, cellulose acetate filter segment. The RTD of the downstream filter segment 202 is about 8 millimetres H2O. The downstream filter segment 202 may be individually wrapped by a plug wrap (not shown). Figures 3a and 3b show a further the aerosol-generating article 300 according to the present invention. The aerosol-generating article 300 comprises an aerosol-generating segment 100 as described above in relation to Figure 1. Figure 3a shows the aerosolgenerating article 300 when the dynamic material is in the high moisture content state. When the dynamic material is in the high moisture content state, the dynamic material may be saturated with water. As the aerosol-generating article 300 is used with an aerosol-generating device, the aerosol-generating segment 100 is heated. As this happens, the water within the dynamic material becomes vaporised and passes out of the aerosol-generating article 300. This is shown by arrows 302.

[0170] As the moisture content of the dynamic material decreases, the volume of the dynamic material, and so the expansion body 103, increases. This increase in volume is shown in Figure 3b. As the volume of the expansion body 103 increases, it exerts outward pressure on the aerosol-generating body 102. This force is shown by arrows 301. This pressure compresses the aerosol-generating body 102 and increases the density of the aerosolgenerating substrate. In addition, where the aerosol-generating article 300 is being used in combination with an aerosol-generating device which includes an external heater, the pressure exerted on the aerosol-generating body 102 by the expansion body 103 also acts to push the aerosol-generating substrate towards the heating element to replace the aerosolgenerating substrate which is initially depleted during the use of the aerosol-generating article 300.

[0171] An aerosol-generating system according to the present invention is shown in Figure 4. The aerosol-generating system comprises the aerosol-generating article 200 described above in relation to Figure 2, and an aerosol-generating device 400.

[0172] The aerosol-generating device 400 comprises a housing (or body) 401 , extending between a downstream end and an upstream end (not shown). The housing 401 comprises a peripheral wall. The peripheral wall defines a heating chamber 402 for receiving an aerosolgenerating article 200. The heating chamber 402 is defined by a closed, upstream end and an open, downstream end. The downstream end of the heating chamber 402 is located at the downstream end of the aerosol-generating device 400. The aerosol-generating article 200 is configured to be received through the open, downstream end of the heating chamber 402 and is configured to abut a closed, upstream end of the heating chamber 402, when the aerosolgenerating article 200 is fully received in the heating chamber 402.

[0173] The aerosol-generating device 400 further comprises a heating element 403 and a power source (not shown) for supplying power to the heating element 403. A controller (not shown) is also provided to control such supply of power to the heating element 403. The heating element 403is configured to controllably heat the aerosol-generating article 200 during use, when the aerosol-generating article 200 is fully received within the heating chamber 402.

[0174] The heating element 403 is a resistive heating element which circumscribes the heating chamber 402 to heat the aerosol-generating article 200 externally when the device 400 is used in combination with the aerosol-generating article 200.

[0175] 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

CLAIMS:

1. An aerosol-generating article for generating an inhalable aerosol, the aerosolgenerating article comprising: an aerosol-generating body, the aerosol-generating body comprising an aerosolgenerating substrate, and an expansion body, the expansion body comprising a dynamic material, the volume of the dynamic material being configured to vary depending on the moisture content of the dynamic material between a high moisture content state in which the dynamic material has a first volume, and a low moisture content state in which the dynamic material has a second volume, the second volume being greater than the first volume , the aerosol-generating body and the expansion body being arranged such that the pressure exerted on the aerosol-generating body by the expansion body is greater when the dynamic material is in the low moisture content state than when the dynamic material is in the high moisture content state.

2. An aerosol-generating article according to claim 1 , wherein the moisture content of the dynamic material is configured to vary between a saturated state and a dry state.

3. An aerosol-generating article according to claim 2, wherein the volume of the dynamic material is configured to be at least 3 times greater in its dry state than in its saturated state.

4. An aerosol-generating article according to claim 2 or claim 3, wherein the expansion body is configured to exert between approximately 0.3 and 0.8 Newtons per square millimetre on the aerosol-generating body when the dynamic material is in its dry state.

5. An aerosol-generating article according to any preceding claim, wherein the aerosolgenerating body and the expansion body have the same length.

6. An aerosol-generating article according to any preceding claim, wherein the aerosolgenerating body circumscribes the expansion body such that the aerosol-generating body is located radially outside the expansion body.

7. An aerosol-generating article according to any preceding claim, wherein the expansion body is porous.

8. An aerosol-generating article according to any preceding claim, wherein the expansion body comprises water absorbed in the dynamic material.

9. An aerosol-generating article according to any preceding claim, wherein the expansion body comprises an aerosol former absorbed in the dynamic material.

10. An aerosol-generating article according to any preceding claim, wherein the dynamic material comprises a hydrophobic material.

11. An aerosol-generating article according to any preceding claim, wherein the dynamic material comprises at least one of a fibrous material and a crimped material.

12. An aerosol-generating article according to any preceding claim, wherein the dynamic material comprises a hydrophobic cellulose material.

13. An aerosol-generating article according to any one of claims 2 to 4, wherein the resistance to draw of the aerosol-generating article when the dynamic material is in its dry state is within 5 percent of the resistance to draw of the aerosol-generating article when the dynamic material is in its saturated state.

14. An aerosol-generating article for generating an inhalable aerosol, the aerosolgenerating article comprising: an aerosol-generating body, the aerosol-generating body comprising an aerosolgenerating substrate, and an expansion body, the expansion body comprising a hydrophobic material.

15. An aerosol-generating system for generating an inhalable aerosol, the system comprising, an aerosol-generating article according to any preceding claim, and an aerosol-generating device comprising a heating chamber for receiving the aerosolgenerating article and a heating element provided in the heating chamber or about the periphery of the heating chamber.

Images