Technical Field

The present disclosure relates generally to aerosol generating articles, and more particularly to an aerosol generating article for use with an aerosol generating device for heating the aerosol generating article to generate an aerosol for inhalation by a user. Embodiments of the present disclosure also relate to a method for producing an aerosol generating article, and/or to an aerosol generating system comprising an aerosol generating device and an aerosol generating article, and/or to a method for generating an aerosol in an aerosol generating device. The present disclosure is particularly applicable to aerosol generating articles for use with a portable (hand-held) aerosol generating device.

Technical Background

The popularity and use of reduced-risk or modified-risk devices (also known as aerosol generating devices or vapour generating devices) has grown rapidly in recent years as an alternative to the use of traditional tobacco products. Various devices and systems are available that heat or warm aerosol generating substances to generate an aerosol for inhalation by a user.

A commonly available reduced-risk or modified-risk device is the heated substrate aerosol generating device, or so-called heat-not-bum device. Devices of this type generate an aerosol or vapour by heating an aerosol generating substrate to a temperature typically in the range 150°C to 300°C. Heating the aerosol generating substrate to a temperature within this range, without burning or combusting the aerosol generating substrate, generates a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device. The aerosol generating substrate typically forms part of a consumable aerosol generating article.

Currently available aerosol generating devices can use one of a number of different approaches to provide heat to the aerosol generating substrate, including resistive heating which makes use of a resistive heating element and induction heating which makes use of an induction coil and an inductively heatable susceptor.

Whichever approach is used to heat the aerosol generating substrate, the characteristics of the aerosol generated by the aerosol generating device are dependent upon a number of factors, including the construction of the aerosol generating article used with the aerosol generating device. There is, therefore, a desire to provide an aerosol generating article which enables the characteristics of the aerosol generated during use of the article to be optimised.

Summary of the Disclosure

According to a first aspect of the present disclosure, there is provided an aerosol generating article for use with an aerosol generating device, the aerosol generating article comprising: a substantially planar aerosol generating substrate comprising at least first and second portions of aerosol generating material; wherein the first and second portions of aerosol generating material have different thermal diffusivities.

The aerosol generating article is for use with an aerosol generating device for heating the aerosol generating substrate, without burning the aerosol generating substrate, to volatise at least one component of the aerosol generating substrate and thereby generate a heated vapour which may cool and condense to form an aerosol for inhalation by a user of the aerosol generating device. The aerosol generating device is a hand-held, portable, device.

In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

By providing first and second portions of aerosol generating material with different thermal diffusivities, the aerosol generating substrate has different heat transfer characteristics than an aerosol generating substrate in which the aerosol generating material has the same thermal diffusivity throughout the substrate. This allows the heating of the aerosol generating substrate to be controlled and may improve the characteristics of the aerosol generated during use of the aerosol generating article in an aerosol generating device and/or may allow a more complete utilisation of the aerosol generating material within the aerosol generating substrate.

Optional features will now be set out. These are applicable singly or in any combination with any aspect of the present disclosure.

The first portion of aerosol generating material may have a higher thermal diffusivity than the second portion of aerosol generating material. The higher thermal diffusivity of the first portion of aerosol generating material may result in more rapid heating of the first portion of aerosol generating material during use of the aerosol generating article in an aerosol generating device. Thus, a vapour or aerosol can be generated quickly by the first portion of aerosol generating material, reducing the time to first puff. The lower thermal diffusivity of the second portion of aerosol generating material may result in slower heating of the second portion of aerosol generating material during use of the aerosol generating article in an aerosol generating device. The second portion may, thus, provide for sustained generation of a vapour or aerosol during continued use of the article, ensuring that vapour or aerosol generation can continue even after the aerosol generating material in the first portion has been depleted and can no longer release sufficient volatile components to generate a vapour or aerosol.

The first portion of aerosol generating material (with its higher thermal diffusivity) may form an outer layer of the substantially planar aerosol generating substrate relative to the second portion of aerosol generating material. Optionally, the first portion of aerosol generating material forms an external layer of the substantially planar aerosol generating substrate. The outer or external layer is heated more rapidly during use of the aerosol generating article in an aerosol generating device, ensuring that a vapour or aerosol can be generated quickly by the external layer of aerosol generating material.

The second portion of aerosol generating material (with its lower thermal diffusivity) may form an internal layer of the substantially planar aerosol generating substrate. Heat can be conducted readily, e.g., from an external heater of an aerosol generating device, through the outer or external layer to the internal layer thanks to the higher thermal diffusivity of the outer or external layer. Thus, the internal layer can be heated to a sufficient temperature to release volatile components from the internal layer and thereby generate a vapour or aerosol. The lower thermal diffusivity of the internal layer ensures that the internal layer is heated more slowly than the outer or external layer, ensuring that vapour or aerosol generation can be sustained by the internal layer even after the first portion of aerosol generating material that forms the outer or external layer has been depleted and can no longer release sufficient volatile components to generate a vapour or aerosol.

The first portion of aerosol generating material may enclose the second portion of aerosol generating material and may form a continuous outer layer at least partially surrounding the second portion of aerosol generating material. Optionally, the first portion of aerosol generating material forms the external surface of the substantially planar aerosol generating substrate. The continuous outer layer or external surface is heated rapidly during use of the aerosol generating article in an aerosol generating device, ensuring that a vapour or aerosol can be generated quickly by the continuous outer layer or external surface of aerosol generating material. Heat can be conducted readily, e.g., from an external heater of an aerosol generating device, through the continuous outer layer or external surface to the (possibly enclosed) second portion of aerosol generating material thanks to the higher thermal diffusivity of the continuous outer layer or external surface. Thus, the second portion of aerosol generating material can be heated to a sufficient temperature to release volatile components and thereby generate a vapour or aerosol. At the same time, the lower thermal diffusivity of the second portion of aerosol generating material ensures that it is heated more slowly than the continuous outer layer or external surface, ensuring that vapour or aerosol generation can be sustained by the second portion even after the first portion of aerosol generating material that forms the continuous outer layer or external surface has been depleted and can no longer release sufficient volatile components to generate a vapour or aerosol.

The first portion of aerosol generating material (with its higher thermal diffusivity) may form a first external layer of the substantially planar aerosol generating substrate. The second portion of aerosol generating material (with its lower thermal diffusivity) may form a second external layer of the substantially planar aerosol generating substrate opposite to the first external layer of the substantially planar aerosol generating substrate. Further portions (e.g., first portions and/or second portions such as layers) of aerosol generating material may be arranged between the oppositely disposed first and second external layers. Providing the first and second portions of aerosol generating material as first and second external layers respectively may allow the heat transfer characteristics to be optimised so that, during use of the aerosol generating article in an aerosol generating device, rapid vapour or aerosol generation is provided by the first external layer and sustained vapour or aerosol generation is provided by the second external layer even after the first portion of aerosol generating material that forms the first external layer has been depleted and can no longer release sufficient volatile components to generate a vapour or aerosol.

The first portion of aerosol generating material may have a lower density (p) than the second portion of aerosol generating material. The first portion of aerosol generating material may have a lower specific heat capacity (C _P ) than the second portion of aerosol generating material. The first portion of aerosol generating material may have a higher thermal conductivity (k) than the second portion of aerosol generating material. The first portion of aerosol generating material may be selected to have one or more of these characteristics to give the first portion of aerosol generating material its higher thermal diffusivity. For example, the first portion of aerosol generating material may have a density lower than 1.0 g/cc or lower than 0.9 g/cc and the second portion of aerosol generating material may have a density higher than 1.2 g/cc or higher than 1.1 g/cc, but preferably lower than 1.5 g/cc. For example, the first portion of aerosol generating material has a density of about 0.9 g/cc and the second portion of aerosol generating material has density of about 1.2 g/cc.

The substantially planar aerosol generating substrate may comprise recesses or embossings in a surface of the substantially planar aerosol generating substrate. This may allow heat conduction within the aerosol generating substrate to be controlled, thereby achieving uniform heating of the first and second portions of the aerosol generating substrate. The recesses or embossings may also facilitate airflow through the aerosol generating substrate.

The aerosol generating substrate may comprise a non-liquid aerosol generating material, for example any type of solid or semi-solid material. Example types of aerosol generating solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut leaves, cut filler, porous material, foam material or sheets. The nonliquid aerosol generating material may comprise plant derived material and in particular, may comprise tobacco or a tobacco material. It may advantageously comprise tobacco and any one or more of cellulose fibres, tobacco stalk fibres and inorganic fillers such as CaCO3.

In an example, the particle size (D50) of the non-liquid aerosol generating material of the second portion of aerosol generating material is smaller than the mean particle size of the non-liquid aerosol generating material of the first portion of aerosol generating material. The smaller particle size within the second portion of aerosol generating material contributes to form a denser material. For example, the mean particle size of the second portion of aerosol generating material is comprised between 10 to 500 microns, preferably between 30 and 250 microns, and the mean particle size of the first portion of aerosol generating material is comprised between 50 and 800 microns, preferably between 80 and 450 microns. Consequently, the aerosol generating device with which the aerosol generating articles are intended for use may be referred to as a “heated tobacco device”, a “heat-not-bum tobacco device”, a “device for vaporising tobacco products”, and the like, with this being interpreted as a device suitable for achieving these effects. The features disclosed herein are equally applicable to devices which are designed to vaporise any aerosol generating substrate.

The aerosol generating substrate may include an aerosol-former.

In an example, the weight ratio of aerosol-former to non-liquid aerosol generating material may be lower in the first portion of aerosol generating material than in the second portion of aerosol generating material. For example, the ratio is from 1 : 8 to 1 : 12 in the first portion of aerosol generating material and from 1 :5 to 1 : 10 in the second portion of aerosol generating material. As the density of aerosol generating material (e.g., tobacco such as tobacco shreds) is significantly lower than the density of the aerosol former, which is typically liquid, the density of the first portion of aerosol generating material can be lowered compared to the second portion of aerosol generating material. The weight of the aerosol former in the first portion of aerosol generating material may be lower than the weight of the aerosol former in the second portion of aerosol generating material. For instance, the first portion of aerosol generating material comprises between 6 and 14 wt. % of aerosol former and the second portion of aerosol generating material comprises between 8 and 20 wt.% of aerosol former. The addition of aerosol former increases the bulk density of the second portion (or layer) of aerosol generating material as well as its specific heat capacity, thereby decreasing its thermal diffusivity relative to the first portion of aerosol generating material. With this proportion of aerosol former in the second portion (or layer) of aerosol generating material, the thermal conductivity of the second portion of aerosol generating material may also increase but not by as much as the two other parameters (density and specific heat capacity) so that the thermal diffusivity of the second portion of aerosol generating material still decreases. Moreover, the weight of aerosol former in the second portion of aerosol generating material can be increased without risking increased condensation or leakage from the second portion of aerosol generating material, especially in embodiments in which the first portion of aerosol generating material forms a continuous outer layer at least partially surrounding the second portion of aerosol generating material, because the “drier” outer first portion of aerosol generating material retards the excess release of aerosol former from the “wetter” inner second portion of aerosol generating material. As an example, the density of aerosol former (e.g., glycerol) is relatively high, in particular about 1.26 g/cc, and the aerosol former content in the second portion is higher than in the first portion, the density of the second portion may be significantly higher than the first portion.

Examples of aerosol-formers include: a polyol such as sorbitol, glycerol, and glycols like propylene glycol or triethylene glycol; a non-polyol such as monohydric alcohols, acids such as lactic acid, glycerol derivatives, esters such as triacetin, triethylene glycol diacetate, triethyl citrate, glycerin or vegetable glycerin. In some embodiments, the aerosol-former may be glycerol, propylene glycol, or a mixture of glycerol and propylene glycol. The aerosol-former excludes water but water may be present in the aerosol generating material in small amounts. Typically, the aerosol generating substrate may comprise an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some embodiments, the aerosol generating substrate may comprise an aerosol-former content of between approximately 10% and approximately 20% on a dry weight basis, and possibly approximately 15% on a dry weight basis.

The aerosol generating article may be configured for use with an electrically-operated aerosol generating device including a heater.

According to a second aspect of the present disclosure, there is provided a method for producing an aerosol generating article according to the first aspect, wherein the method comprises extruding the first and second portions of aerosol generating material to form the substantially planar aerosol generating substrate. By extruding the first and second portions of aerosol generating material, the aerosol generating article can be easily manufactured.

The method may comprise co-extruding the first and second portions of aerosol generating material to form the substantially planar aerosol generating substrate. Coextruding the first and second portions of aerosol generating material may facilitate rapid manufacture of the aerosol generating article.

The method may comprise separately extruding the first and second portions of aerosol generating material and thereafter assembling the separately extruded first and second portions of aerosol generating material to form the substantially planar aerosol generating substrate. Separately extruding the first and second portions of aerosol generating material may allow the characteristics, such as layer thickness, of the first and second portions to be carefully controlled.

The step of assembling the separately extruded first and second portions of aerosol generating material may comprise laminating the first and second portions of aerosol generating material. A close and reliable contact between the first and second portions of aerosol generating material is thereby assured, which may improve heat conduction through the aerosol generating substrate.

According to a third aspect of the present disclosure, there is provided an aerosol generating system comprising: an aerosol generating device including a heater; and an aerosol generating article according to the first aspect; wherein the first portion of aerosol generating material has a higher thermal diffusivity than the second portion of aerosol generating material, and wherein at least part of the first portion of aerosol generating material is positioned closer to the heater than the second portion of aerosol generating material.

According to a fourth aspect of the present disclosure, there is provided a method for generating an aerosol in an aerosol generating device including a heater by heating an aerosol generating article according to the first aspect, wherein the first portion of aerosol generating material has a higher thermal diffusivity than the second portion of aerosol generating material, and wherein the method comprises positioning at least part of the first portion of aerosol generating material closer to the heater than the second portion of aerosol generating material.

By positioning at least part of the first portion of aerosol generating material (with its higher thermal diffusivity) closer to the heater, at least this part of the first portion of aerosol generating material is heated rapidly by the heater. Thus, a vapour or aerosol can be generated quickly by at least this part of the first portion of aerosol generating material, reducing the time to first puff. Heat is also readily conducted by at least this part of the first portion of aerosol generating material to the second portion of aerosol generating material, thanks to the higher thermal diffusivity of the first portion of aerosol generating material. The second portion of aerosol generating material can, therefore, be heated to a sufficient temperature to release volatile components and thereby generate a vapour or aerosol. At the same time, the lower thermal diffusivity of the second portion of aerosol generating material ensures that it is heated more slowly than the first portion of aerosol generating material, ensuring that aerosol or vapour generation can be sustained by the second portion even after the first portion of aerosol generating material has been depleted and can no longer release sufficient volatile components to generate a vapour or aerosol.

The heater may be a resistive heater or may be an inductive heater. Upon heating, the aerosol generating substrate, and specifically the first and second portions of the aerosol generating substrate, may release volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco flavouring.

Brief Description of the Drawings

Figure 1 is a diagrammatic plan view of a first example of an aerosol generating article; Figure 2 is an enlarged diagrammatic cross-sectional view along the line A-A in Figure 1 and also illustrates a heater of an aerosol generating device; Figure 3 is a diagrammatic cross-sectional view of an aerosol generating system comprising an aerosol generating device and the first example of the aerosol generating article illustrated in Figures 1 and 2;

Figure 4 is a diagrammatic cross-sectional view similar to Figure 2 of a second example of an aerosol generating article and a heater of an aerosol generating device;

Figure 5 is a diagrammatic cross-sectional view similar to Figure 2 of a third example of an aerosol generating article and a heater of an aerosol generating device; and Figure 6 is a diagrammatic cross-sectional view similar to Figure 2 of a fourth example of an aerosol generating article and a heater of an aerosol generating device.

Detailed Description of Embodiments

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

Referring initially to Figures 1 and 2, there is shown a first example of an aerosol generating article 1 for use with an electrically-operated aerosol generating device 102, an example of which will be described below with reference to Figure 3. The aerosol generating article 1 is substantially planar and has first and second ends 10, 12. A longitudinal axis extends between the first end 10 and the second end 12 to define a longitudinal direction of the aerosol generating article 1 , and airflow through the aerosol generating article 1 is typically in the longitudinal direction.

The aerosol generating article 1 comprises a substantially planar aerosol generating substrate 14. The aerosol generating substrate 14 has a flat rectangular shape with a pair of oppositely disposed main surfaces 14a, 14b. The aerosol generating article 1 is a consumable, or disposable, article in which the aerosol generating substrate 14 may comprise tobacco or a tobacco material (such as reconstituted tobacco) which includes nicotine as a volatile component. The aerosol generating substrate 14 typically also includes an aerosol-former (humectant) such as propylene glycol or glycerine or a combination thereof. The aerosol generating substrate 14 comprises first, second and third portions 16, 18, 20 of aerosol generating material, and each of these first, second and third portions 16, 18, 20 of aerosol generating material have different thermal diffusivities. In the first example illustrated in Figure 1, the first portion 16 of aerosol generating material forms an outer or external layer 22 of the aerosol generating substrate 14, and more particularly provides a continuous external surface 24 which at least partially encloses the second and third portions 18, 20 of aerosol generating material in the sense that the second and third portions 18, 20 of aerosol generating material may be exposed at the first and second ends 10, 12 of the aerosol generating article 1, for example as shown in Figure 3. Both of the second and third portions 18, 20 of aerosol generating material form internal layers 26, 28 of the aerosol generating substrate 14. The second portion 18 of aerosol generating material (internal layer 26) at least partially encloses the third portion 20 of aerosol generating material (internal layer 28).

Referring now to Figure 3, there is shown an aerosol generating system 100 comprising an aerosol generating device 102 and a first example of an aerosol generating article 1 as described above with reference to Figures 1 and 2. It will be appreciated that the aerosol generating device 102 could be used in combination with an alternative aerosol generating article according to the present disclosure, such as the second, third or fourth examples of the aerosol generating articles 2, 3, 4 described below with reference to Figures 4 to 6.

The aerosol generating device 102 comprises a receiving chamber 106 and a heater 104 positioned in a device body 108 to provide heat to the receiving chamber 106. The heater 104 may be a resistive heater or may alternatively be an induction heater comprising a susceptor and an electromagnetic field generator including an induction coil.

In use, a user inserts the aerosol generating article 1 into the receiving chamber 106. The aerosol generating device 102 may include a cover 110 and a pivotal mounting 112 that allows the cover 110 to be moved between a closed position shown in Figure 3 and an open position (not shown). As will be understood by one of ordinary skill in the art, a user must pivot the cover 110 to the open position to permit insertion of the aerosol generating article 1 into the receiving chamber 106 and then pivot the cover back to the closed position shown in Figure 3 to retain the aerosol generating article 1 in position in the receiving chamber 106.

The aerosol generating device 102 includes a power source 114, e.g., a rechargeable battery, and a controller 116, both of which are connected to the heater 104. The heater 104 may be actuated manually, e.g., via a user interface such as a button on the aerosol generating device 102, or may be actuated automatically in response to a user drawing on a mouthpiece 118 of the aerosol generating device 102. The aerosol generating device 102 includes one or more air inlets 120 to allow air to flow into the aerosol generating article 1 and through the aerosol generating substrate 14 in the longitudinal direction, i.e., between the first and second ends 10, 12 of the aerosol generating article 1. The airflow direction is illustrated by the arrow in Figure 3.

With the aerosol generating article 1 positioned in the receiving chamber 106, power is supplied from the power source 114 to the heater 104 (either by a manual or automatic actuation of the heater 104 as described above), thereby heating the aerosol generating substrate 14 without burning it to release one or more volatile components. The volatile components are entrained in the air flowing through the aerosol generating substrate 14 thereby forming a vapour. The vapour cools and condenses as it flows through the aerosol generating substrate 14 to form an aerosol which is inhaled by a user through the mouthpiece 118 of the aerosol generating device 102.

When the aerosol generating substrate 14 becomes depleted and no longer releases sufficient volatile components to generate an aerosol with acceptable qualities, the aerosol generating article 1 can be removed from the receiving chamber 106 after pivoting the cover 110 to the open position, and a replacement aerosol generating article 1 can be inserted in its place.

As noted above, the first, second and third portions 16, 18, 20 of aerosol generating material that form the aerosol generating substrate 14 have different thermal diffusivities. More particularly, the first portion 16 of aerosol generating material has a higher thermal diffusivity than the second portion 18 of aerosol generating material, and the second portion 18 of aerosol generating material has a higher thermal diffusivity than the third portion 20 of aerosol generating material. Thus, it will be understood that the first portion 16 of aerosol generating material has the highest thermal diffusivity and that the third portion 20 of aerosol generating material has the lowest thermal diffusivity. These different thermal diffusivities are advantageous as the different regions of the aerosol generating substrate 14 in which the first, second and third portions 16, 18, 20 of aerosol generating material are provided have different heat transfer characteristics which allow for more uniform heating of the aerosol generating substrate 14 and a more complete utilisation of the aerosol generating material that forms the aerosol generating substrate 14. This in turn provides for more reliable aerosol generation and, thus, a more satisfactory user experience.

More particularly, the first portion 16 of aerosol generating material is heated more rapidly than the second or third portions 18, 20 of aerosol generating material due to its higher thermal diffusivity. Consequently, volatile components are released by the first portion 16 of aerosol generating material more quickly than by the second or third portions 18, 20 of aerosol generating material, reducing the time to first puff and thus improving the user experience.

The lower thermal diffusivities of the second and third portions 18, 20 of aerosol generating material result in slower heating of the second and third portions 18, 20 of aerosol generating material, with the third portion 20 of aerosol generating material heating up more slowly than the second portion 18 of aerosol generating material. The second and third portions 18, 20 of aerosol generating material provide for sustained generation of a vapour or aerosol during continued use of the article 1, ensuring that vapour or aerosol generation can continue even after the first portion 16 of aerosol generating material has been depleted and can no longer release sufficient volatile components to generate a vapour or aerosol.

Thermal diffusivity («) is defined by the following equation: k a ⁼ pCp where k = thermal conductivity, p = density and C _p = specific heat capacity.

Thermal diffusivity of the aerosol generating material can be determined by the modified transient plane source (MTPS) technique using a Mathis TC-01 instrument calibrated with standard conditions at 25°C or by laser flash technique.

Since thermal diffusivity is inversely proportional to density and specific heat capacity, it will be understood that the first portion 16 of aerosol generating material should have a lower density and specific heat capacity than the second portion 18 of aerosol generating material, and the second portion 18 of aerosol generating material should have a lower density and specific heat capacity than the third portion 20 of aerosol generating material. Accordingly, the first portion 16 of aerosol generating material has the lowest density and/or heat specific capacity and the third portion 20 of aerosol generating material has the highest density and/or heat capacity. As illustrated in Figures 2 and 3, at least part of the first portion 16 of aerosol generating material is positioned closer to the heater 104 than the second portion 18 of aerosol generating material. Similarly, at least part of the second portion 18 of aerosol generating material is positioned closer to the heater 104 than the third portion 20 of aerosol generating material. With this arrangement, a heat diffusivity gradient is obtained. In particular, since the first portion 16 of aerosol generating material has better heat diffusion performance than the second portion 18 of aerosol generating material, the first portion 16 heats faster thereby allowing TPM (Total Particulate Matter) in the vapour to rise high as the heating ramps up. Likewise, since the third portion 20 of aerosol generating material has lower heat diffusion performance than the second portion 18 of aerosol generating material, the third portion 20 heats up slower and so ensures a sustainable and even release of TPM until the end of the vaporisation cycle or all intended puffs of the vaporization session. The differing thermal diffusivities of the first, second and third portions 16, 18, 20 of aerosol generating material may be obtained by varying the density p of the aerosol generating material in the first, second and third portions 16, 18, 20 and/or by providing aerosol generating material in one or more of the first, second and third portions 16, 18, 20 with different specific heat capacities C _p . For example, the first portion 16 of aerosol generating material may have a lower specific heat capacity C _p and/or a lower density p than the second portion 18 of aerosol generating material. Likewise, the second portion 18 of aerosol generating material may have a lower specific heat capacity C _p and/or a lower density p than the third portion 20 of aerosol generating material.

The aerosol generating article 1 is typically produced by an extrusion process which involves extruding the first, second and third portions 16, 18, 20 of aerosol generating material to form the aerosol generating substrate 14.

In some embodiments, a co-extrusion process may be used, so that the first, second and third portions 16, 18, 20 of aerosol generating material are simultaneously extruded (i.e., co-extruded) by a single extruder to form a substrate web comprising the first, second and third portions 16, 18, 20 of aerosol generating material. The substrate web can then be cut at longitudinally spaced positions to form a plurality of aerosol generating articles 1.

In other embodiments, the first, second and third portions 16, 18, 20 of aerosol generating material may be separately extruded, by separate extruders, to form the first, second and third portions 16, 18, 20 of aerosol generating material. The separately extruded first, second and third portions 16, 18, 20 of aerosol generating material are then assembled or combined, for example by a lamination process, to form a substrate web comprising the first, second and third portions 16, 18, 20 of aerosol generating material. The substrate web can then be cut at longitudinally spaced positions to form a plurality of aerosol generating articles 1.

Referring now to Figure 4, there is shown a second example of an aerosol generating article 2. The aerosol generating article 2 is similar to the aerosol generating article 1 described above with reference to Figures 1 and 2 and corresponding features are identified using the same reference numerals.

Like the aerosol generating article 1, the aerosol generating article 2 comprises a substantially planar aerosol generating substrate 14 having a flat rectangular shape with a pair of oppositely disposed main surfaces 14a, 14b. In this second example, the aerosol generating substrate 14 comprises a plurality of recesses (or embossings) 30 which extend in the longitudinal direction. The recesses 30 may facilitate airflow through the aerosol generating article 2, during use in an aerosol generating device 102, from the first end 10 towards the second end 12. The plurality of recesses (or embossings) may be arranged on the surface 14b opposite to the surface 14a in contact with the heater 104.

The aerosol generating substrate 14 comprises first and second portions 16, 18 of aerosol generating material. The first portion 16 of aerosol generating material again forms an outer or external layer 22 of the aerosol generating substrate 14, and more particularly provides a continuous external surface 24 which at least partially encloses the second portion 18 of aerosol generating material, in the sense that the second portion 18 of aerosol generating material may be exposed at the first and second ends 10, 12 of the aerosol generating article 1. Thus, the second portion 18 of aerosol generating material forms an internal layer 26 of the aerosol generating substrate 14.

The first portion 16 of aerosol generating material that forms the external layer 22 of the aerosol generating substrate 14 has a higher thermal diffusivity than the second portion 18 of aerosol generating material that forms the internal layer 26 of the aerosol generating substrate, and at least part of the first portion 16 of aerosol generating material is positioned closer to the heater 104 during use of the aerosol generating article 2 in an aerosol generating device 102. This provides the same advantages that have already been discussed above in relation to the first example of the aerosol generating article 1. Referring now to Figure 5, there is shown a third example of an aerosol generating article 3. The aerosol generating article 3 is similar to the aerosol generating article 1 described above with reference to Figures 1 and 2 and corresponding features are identified using the same reference numerals.

Like the aerosol generating article 1, the aerosol generating article 3 comprises a substantially planar aerosol generating substrate 14 having a flat rectangular shape with a pair of oppositely disposed main surfaces 14a, 14b. The aerosol generating substrate 14 comprises a plurality of first portions 16 of aerosol generating material and a plurality of second portions 18 of aerosol generating material. The first and second portions 16, 18 of aerosol generating material are arranged as alternating layers between the main surfaces 14a, 14b. In this example, the outermost first portions 16 of aerosol generating material form an external layer 22 at both of the main surfaces 14a, 14b of the aerosol generating substrate 14.

The first portions 16 of aerosol generating material have a higher thermal diffusivity than the second portions 18 of aerosol generating material. The first portion 16 of aerosol generating material that forms the external layer 22 at the main surface 14a is positioned closer to the heater 104 than any of the second portions 18 of aerosol generating material during use of the aerosol generating article 3 in an aerosol generating device 102. This provides the same advantages that have already been discussed above in relation to the first example of the aerosol generating article 1. Furthermore, the layered (or wafer-like) construction provides for a controlled and uniform heat transfer through the aerosol generating substrate 14, from the main surface 14a adjacent to the heater 104 to the main surface 14b positioned away from the heater 104, thus ensuring that a vapour or aerosol with suitable characteristics is generated during use of the article 3 in an aerosol generating device 102.

Referring now to Figure 6, there is shown a fourth example of an aerosol generating article 4. The aerosol generating article 4 is similar to the aerosol generating articles 2, 3 described above with reference to Figures 4 and 5 and corresponding features are identified using the same reference numerals. Like the aerosol generating article 2, the aerosol generating article 4 comprises a substantially planar aerosol generating substrate 14 having a flat rectangular shape with a pair of oppositely disposed main surfaces 14a, 14b and a plurality of recesses (or embossings) 30 which extend in the longitudinal direction. As noted above, the recesses 30 may facilitate airflow through the aerosol generating article 4 during use in an aerosol generating device 102.

The aerosol generating substrate 14 comprises a plurality of first portions 16 of aerosol generating material and a plurality of second portions 18 of aerosol generating material. The first and second portions 16, 18 of aerosol generating material are arranged as alternating layers between the main surfaces 14a, 14b. In this example, a first portion 16 of aerosol generating material forms an external layer 22 at the main surface 14a of the aerosol generating substrate 14.

The first portions 16 of aerosol generating material have a higher thermal diffusivity than the second portions 18 of aerosol generating material. The first portion 16 of aerosol generating material that forms the external layer 22 at the main surface 14a is positioned closer to the heater 104 than any of the second portions 16 of aerosol generating material during use of the aerosol generating article 4 in an aerosol generating device 102. This provides the same advantages that have already been discussed above in relation to the first example of the aerosol generating article 1. Furthermore, the layered (or wafer-like) construction provides for a controlled and uniform heat transfer through the aerosol generating substrate 14, from the main surface 14a adjacent to the heater 104 to the main surface 14b positioned away from the heater 104, thus ensuring that a vapour or aerosol with suitable characteristics is generated during use of the article 4 in an aerosol generating device 102.

Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments. Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.