Aerosol generating product, method of forming hollow tubular aerosol-forming substrate, and aerosol generating system

Abstract

FIELD: aerosol generating system.SUBSTANCE: group of inventions relates to an aerosol generating article, a method for forming a hollow tubular aerosol-forming substrate for an aerosol generating article, and an aerosol generating system. An aerosol generating article for producing an inhalable aerosol upon heating comprises a plurality of components including an aerosol-forming substrate, wherein the aerosol-forming substrate has the form of a hollow tubular portion that forms a substrate cavity extending between an upstream end of the aerosol-forming substrate and a downstream end of the aerosol-forming substrate, wherein the aerosol-forming substrate comprises a plurality of heat-conducting particles and an aerosol-forming substance, each of the plurality of heat-conducting particles having a thermal conductivity greater than 0.3 W / (m⋅K) in at least one direction at 25 °C and said substrate is made in the form of a tube having an outer diameter and an inner diameter, wherein the inner diameter is from 2.5 to 19 mm.EFFECT: combination of a tubular geometric shape and heat-conducting particles allows for faster time-to-first-draw, improved aerosol extraction efficiency, and a lighter weight aerosol-generating device.15 cl, 4 dwg

Description

[0001] The present invention relates to an aerosol-generating article (for generating an aerosol) comprising a tubular aerosol-forming substrate. The present invention also relates to a method for producing an aerosol-forming substrate for such an article and an aerosol-generating system (for generating an aerosol).

[0002] 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, the aerosol is generated by heat transfer from a heat source to a physically separate aerosol-generating substrate or material, which may be positioned 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.

[0003] A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol-generating devices in which the aerosol is generated by transferring heat from one or more electrical heating elements of the aerosol-generating device to the aerosol-generating substrate of the heated aerosol-generating article. For example, electrically heated aerosol-generating devices have been proposed that include an internal heater plate that is adapted for insertion into the aerosol-generating substrate. The use of an aerosol-generating article in combination with an external heating system is also known.For example, document WO-A-2020 / 115151 describes the provision of an external heating element located around the periphery of an aerosol-generating article when the aerosol-generating article is contained within a cavity of an aerosol-generating device. Alternatively, document WO-A-2015 / 176898 proposed inductively heated aerosol-generating articles containing an aerosol-generating substrate and a current collector located within the aerosol-generating substrate.

[0004] In general, it can be difficult to ensure efficient heating of the aerosol-generating substrate across the entire substrate core. The parts of the substrate closest to the heating element will inevitably heat up most efficiently, while imperfect heat transfer through the substrate means that the parts of the substrate furthest from the heating element may not be heated effectively. Therefore, aerosol generation from these inefficiently heated parts of the substrate is suboptimal, and in some cases, parts of the substrate may not reach a temperature high enough to generate aerosol during use.For example, if an external heating element is used to heat an aerosol-generating substrate rod, as described above, the central portion of the aerosol-generating substrate rod is less likely to generate as much aerosol as the outer portions of the rod, and in some cases may not generate any aerosol at all. Overall, therefore, aerosol generation from the aerosol-generating rod is likely to be inefficient, with potential loss of some aerosol-generating substrate.

[0005] Furthermore, the aerosol is typically not generated by the aerosol-generating substrate immediately after activation of the heating element. This is due to a preheating period after activation of the heating element, during which the aerosol-generating substrate heats up to the temperature required for aerosol generation. As such, there may be a relatively long time between activation of the heating element and the generation of a perceptibly acceptable aerosol for inhalation by the user.

[0006] Therefore, it would be desirable to provide an aerosol-generating article having an aerosol-generating substrate that is adapted to ensure more efficient aerosolization of the aerosol-generating substrate and that reduces the loss of substrate materials, such as tobacco. It would also be desirable to provide such an aerosol-generating article that can provide a relatively short preheating time so that a perceptibly acceptable aerosol can be delivered to the user soon after the initiation of heating of the aerosol-generating substrate. It would also be desirable to provide such an aerosol-generating article that can ensure optimized aerosol delivery from the aerosol-generating substrate. It would be particularly desirable to provide such an aerosol-generating article with a relatively simple design so that it can be manufactured cost-effectively and incorporated into existing product designs.It would also be desirable to provide such a product that is easily adaptable so that it can be heated by different types of heating devices, including induction and resistive heating devices.

[0007] Known aerosol-forming substrates typically have relatively low thermal conductivity values. Low thermal conductivity of an aerosol-forming substrate can lead to a relatively large temperature gradient within the aerosol-forming substrate during use. This may mean that the parts of the aerosol-forming substrate located farthest from the heating element do not reach high temperatures and therefore do not release as many volatile compounds as they would if the aerosol-forming substrate had a higher thermal conductivity. In other words, low thermal conductivity of an aerosol-forming substrate can, undesirably, lead to inefficient use of the aerosol-forming substrate.

[0008] According to the present invention, an aerosol-generating article is provided for producing an inhalable aerosol upon heating. The aerosol-generating article may comprise a plurality of components, including an aerosol-forming substrate. The aerosol-forming substrate may be in the form of a hollow tubular portion, preferably defining a substrate cavity extending between an upstream end of the aerosol-forming substrate and a downstream end of the aerosol-forming substrate. The aerosol-forming substrate preferably comprises a plurality of heat-conducting particles and an aerosol-forming substance.

[0009] For example, an aerosol-generating article may be provided for producing an inhalable aerosol upon heating, wherein the aerosol-generating article comprises a plurality of components including an aerosol-forming substrate, wherein the aerosol-forming substrate has the shape of a hollow tubular portion of a cavity-forming substrate extending between an upstream end of the aerosol-forming substrate and a downstream end of the aerosol-forming substrate, and in which the aerosol-forming substrate comprises a plurality of heat-conducting particles and an aerosol-forming substance.

[0010] Using a tubular geometric shape for the aerosol-forming substrate can help eliminate the influence of temperature gradients on substrate heating. With a tubular geometric shape, the substrate has no core, and the aerosol-forming material is concentrated in the areas of the substrate that are heated, either internally or externally. This allows for a significant increase in extraction efficiency, which in turn can reduce the total amount of substrate required for the user's experience. Reducing the substrate's mass reduces heating inertia and therefore can reduce the time it takes to heat to a sufficient temperature, thereby reducing the time to first hit. Using a thermally conductive substrate can significantly enhance the benefits of a tubular geometric substrate.A substrate with increased or improved thermal conductivity, achieved through the presence of thermally conductive particles, can further reduce substrate inertia and further reduce time to first draw and improve overall extraction efficiency. By selecting specific thermally conductive particles, such as graphite or expanded graphite, the substrate's weight can be further reduced. Reducing the overall mass of the aerosol-generating substrate, which is necessary for a proper user experience, has several advantages, including reducing overall thermal inertia and reducing the weight of the aerosol-generating product containing the substrate. Reducing the product's weight can reduce shipping costs and energy associated with shipping, and may also provide tax benefits in some jurisdictions.

[0011] The aerosol-generating article according to the present invention can be particularly advantageously employed in an aerosol-generating system using gradual heating or zone heating. The aerosol-generating article according to the present invention can also be particularly advantageously employed in an aerosol-generating system using on-demand heating.

[0012] The aerosol-forming substrate may comprise, on a dry weight basis, from 5 to 95 weight percent [wt.%] of thermally conductive particles, such as from 10 to 90 weight % of thermally conductive particles. The aerosol-forming substrate may comprise, on a dry weight basis, from 7 to 60 weight % of an aerosol-forming substance. The aerosol-forming substrate may comprise, on a dry weight basis, from 2 to 20 weight % of fibers. The aerosol-forming substrate may comprise, on a dry weight basis, from 2 to 10 weight % of a binder. Each of the thermally conductive particles may consist of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond.

[0013] There can thus be provided an aerosol-forming substrate comprising, on a dry weight basis: 10 to 90% by weight of heat-conducting particles; 7 to 60% by weight of an aerosol-forming agent; 2 to 20% by weight of fibers; and 2 to 10% by weight of a binder, wherein each of the heat-conducting particles consists of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond.

[0014] The aerosol-generating article may contain, on a dry weight basis, from 5 to 95% by weight, such as from 10 to 90% by weight, of thermally conductive particles, wherein each thermally conductive particle of the thermally conductive particles has a thermal conductivity of at least 1 W / (m⋅K). The thermal conductivity can be measured in at least one direction of the particle. The thermal conductivity can be measured at a temperature of 25 degrees Celsius.

[0015] When the term "heat-conducting particles" is used to refer to particles containing carbon, such as particles containing or consisting of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond, the heat-conducting particles may be referred to as carbon particles or carbon-containing particles.

[0016] Advantageously, thermally conductive particles can increase the thermal conductivity of the aerosol-forming substrate. Increased thermal conductivity of the substrate can ensure a more uniform temperature distribution throughout the substrate during use. This can result in a larger proportion of the aerosol-forming substrate reaching a temperature high enough to release volatile compounds, thereby leading to higher utilization efficiency of the aerosol-forming substrate. Furthermore, increased thermal conductivity of the substrate can allow a heater, such as a heating plate configured to heat the substrate, to operate at a lower temperature and thus require less energy. Furthermore, increased thermal conductivity of the substrate can allow the heater to heat the substrate to a temperature at which volatile compounds are released in a shorter time.Thus, increased thermal conductivity can reduce the time required to generate an inhalable aerosol for the user.

[0017] Advantageously, one or both of the fibers and the binder can increase the tensile strength of the aerosol-forming substrate material. Increased tensile strength can, for example, enable the production of a sheet of aerosol-forming material using existing manufacturing equipment, wherein the sheet can be formed into a tube to form the aerosol-forming substrate.

[0018] The aerosol-forming substrate can have a thermal conductivity of at least 0.05, 0.1, 0.15, 0.2, 0.22, 0.3, 0.4 or 0.5 W / (m⋅K) in at least one direction or in all directions at 25 degrees Celsius. This thermal conductivity can be measured at a substrate moisture content of 0 to 20 or 5 to 15, for example, approximately 10%. This thermal conductivity can be measured when the substrate contains 0 to 20 or 5 to 15, for example, approximately 10% by weight of water. The moisture or water content of the substrate can be measured using a titration method. The moisture or water content of the substrate can be measured using the Karl Fischer method.

[0019] Optionally, some or all of the thermally conductive particles contain at least 10, 30, 50, 70, 90, 95, 98, or 99% by weight carbon.

[0020] Optionally, some or all of the thermally conductive particles are graphite particles. Optionally, some or all of the thermally conductive particles are expanded graphite particles. Optionally, some or all of the thermally conductive particles are graphene particles. Optionally, some or all of the thermally conductive particles are carbon nanotubes or carbon nanotube particles. Optionally, some or all of the thermally conductive particles are charcoal particles. Optionally, some or all of the thermally conductive particles are diamond particles, such as synthetic diamond particles. Advantageously, such materials can have relatively high thermal conductivities.

[0021] Expanded graphite may have a density less than 2, 1.8, 1.5, 1.2, 1, 0.8 or 0.5, 0.2, 0.1, 0.05, 0.02 grams per cubic centimeter (g / cm 3). Expanded graphite may have a density greater than 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, or 1.8 grams per cubic centimeter (g / cm 3 ). Expanded graphite may have a density of 0.01 to 3, 0.01 to 2, 0.01 to 1.8, 0.01 to 1.5, 0.01 to 1.2, 0.01 to 1, 0.01 to 0.8, 0.01 to 0.5, 0.02 to 3, 0.02 to 2, 0.02 to 1.8, 0.02 to 1.5, 0.02 to 1.2, 0.02 to 1, 0.02 to 0.8, 0.02 to 0.5, 0.01 to 3, 0.05 to 2, 0.05 to 1.8, 0.05 to 1.5, 0.05 to 1.2, from 0.05 to 1, from 0.05 to 0.8, from 0.05 to 0.5 g / cm 3, from 0.1 to 3, from 0.1 to 2, from 0.1 to 1.8, from 0.1 to 1.5, from 0.1 to 1.2, from 0.1 to 1, from 0.1 to 0.8, from 0.1 to 0.5, from 0.2 to 3, from 0.2 to 2, from 0.2 to 1.8, from 0.2 to 1.5, from 0.2 to 1.2, from 0.2 to 1, from 0.2 to 0.8, from 0.2 to 0.5, from 0.5 to 3, from 0.5 to 2, from 0.5 to 1.8, from 0.5 to 1.5, from 0.5 to 1.2, from 0.5 to 1, from 0.5 to 0.8, from 0.8 to 3, 0.8 to 2, 0.8 to 1.8, 0.8 to 1.5, 0.8 to 1.2, 0.8 to 1 gram per cubic centimeter (g / cm 3 ). 0022 Optionally, in aspects where each of the thermally conductive particles optionally consists of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond, some or all of the thermally conductive particles comprise a metal. Alternatively or additionally, some or all of the thermally conductive particles comprise an alloy. Alternatively or additionally, some or all of the thermally conductive particles comprise an intermetallic compound. Advantageously, such materials can have relatively high thermal conductivities.

[0023] Optionally, according to alternative aspects, where each of the thermally conductive particles optionally consists of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond, some or all of the thermally conductive particles comprise one or more of silicon carbide, silver, copper, gold, aluminum nitride, aluminum, tungsten, and boron nitride. Optionally, some or all of the thermally conductive particles are carbide particles. Optionally, some or all of the thermally conductive particles are silver particles. Optionally, some or all of the thermally conductive particles are copper particles. Optionally, some or all of the thermally conductive particles are gold particles. Optionally, some or all of the thermally conductive particles are aluminum nitride particles. Optionally, some or all of the thermally conductive particles are aluminum particles.Not all or some of the thermally conductive particles are necessarily tungsten particles. Not all or some of the thermally conductive particles are necessarily boron nitride particles. Such materials can advantageously have relatively high thermal conductivities.

[0024] Each heat-conducting particle can have a "particle size." The meaning of the term "particle size" and the method for measuring particle size will be explained later.

[0025] Heat-conducting particles can be characterized by a particle size distribution. The particle size distribution can have particle sizes with numbers D10, D50, and D90. A particle size D10 by number is defined such that 10% of the particles have a particle size that is less than or equal to the particle size D10 by number. Similarly, a particle size D50 by number is defined such that 50% of the particles have a particle size that is less than or equal to the particle size D50 by number. Thus, the particle size D50 by number can be called the average particle size. A particle size D90 by number is defined such that 90% of the particles have a particle size that is less than or equal to the particle size D90 by number.

[0026] Thus, if there were 1000 particles in the distribution and the particles were ordered by increasing particle size, one would expect the D10 particle size in number to be approximately equal to the 100th particle size, the D50 particle size in number to be approximately equal to the 500th particle size, and the D90 particle size in number to be approximately equal to the 900th particle size.

[0027] The particle size distribution can have particle sizes with volumes D10, D50, and D90. The particle size D10 by volume is defined such that 10% of the sum of the volumes of all particles is due to the sum of the volumes of particles with a particle size less than or equal to the particle size D10 by volume. Similarly, the particle size D50 by volume is defined such that 50% of the sum of the volumes of particles is due to the sum of the volumes of particles with a particle size less than or equal to the particle size D50 by volume. And the particle size D90 by volume is defined such that 90% of the sum of the volumes of all particles is due to the sum of the volumes of particles with a particle size less than or equal to the particle size D90 by volume.

[0028] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by number, wherein the D10 particle size by number is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200 or 500 microns.

[0029] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by number, wherein the D10 particle size by number is not more than 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0030] When selecting particle size, a compromise must be found. Larger, thermally conductive particles can preferentially increase the thermal conductivity of the aerosol-forming substrate to a greater extent than smaller, thermally conductive particles. However, larger, thermally conductive particles can reduce the space available for the aerosol-forming material within the substrate.

[0031] Optionally, the heat-conducting particles have a particle size distribution with a D50 particle size by number, wherein the D50 particle size by number is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200 or 500 microns.

[0032] Optionally, the heat-conducting particles have a particle size distribution with a D50 particle size by number, wherein the D50 particle size by number is not more than 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0033] Optionally, the heat-conducting particles have a particle size distribution with a D90 particle size by number, wherein the D90 particle size by number is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200 or 500 microns.

[0034] Optionally, the heat-conducting particles have a particle size distribution with a D90 particle size by number, wherein the D90 particle size by number is not more than 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0035] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by number and a D90 particle size by number, wherein the D90 particle size by number is not more than 50, 40, 30, 20, 10 or 5 times larger than the D10 particle size by number.

[0036] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by number and a D90 particle size by number, wherein the D90 particle size by number is at least 1.5, 2, 3, 5, 10 or 20 times larger than the D10 particle size by number.

[0037] A compromise may be necessary with respect to particle size distribution. A denser particle size distribution, for example, characterized by a smaller ratio between the D90 and D10 particle sizes, may advantageously provide more uniform thermal conductivity throughout the aerosol-forming substrate. This is because there will be fewer differences in particle size across the substrate. This may advantageously allow for more efficient use of the aerosol-forming material throughout the aerosol-forming substrate. However, achieving a denser particle size distribution may be, unadvantageously, more difficult and expensive. The inventors have found that the particle size distributions described above can provide an optimal compromise between these two factors.

[0038] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by volume, wherein the D10 particle size by volume is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200 or 500 microns.

[0039] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by volume, wherein the D10 particle size by volume is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0040] Optionally, the heat-conducting particles have a particle size distribution with a D50 particle size by volume, wherein the D50 particle size by volume is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200 or 500 microns.

[0041] Optionally, the heat-conducting particles have a particle size distribution with a D50 particle size by volume, wherein the D50 particle size by volume is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0042] Optionally, the thermally conductive particles have a particle size distribution with a D90 particle size by volume, wherein the D90 particle size by volume is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200 or 500 microns.

[0043] Optionally, the heat-conducting particles have a particle size distribution with a D90 particle size by volume, wherein the D90 particle size by volume is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0044] It may be particularly preferable for the heat-conducting particles to have a particle size distribution with a D10 particle size by volume of 1 to 20 microns. Alternatively or additionally, it may be particularly preferable for the heat-conducting particles to have a particle size distribution with a D90 particle size by volume of 50 to 300 microns or 50 to 200 microns.

[0045] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by volume and a D90 particle size by volume, wherein the D90 particle size by volume is not more than 50, 40, 30, 20, 10, or 5 times larger than the D10 particle size by volume.

[0046] Optionally, the heat-conducting particles have a particle size distribution with a D10 particle size by volume and a D90 particle size by volume, wherein the D90 particle size by volume is at least 1.5, 2, 3, 5, 10 or 20 times larger than the D10 particle size by volume.

[0047] As explained above, a compromise must be made regarding the particle size distribution, and the inventors found that the particle size distributions presented above can provide an optimal compromise.

[0048] Optionally, each of the thermally conductive particles has a particle size of at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200 or 500 microns. Optionally, each of the thermally conductive particles has a particle size of no more than 1000, 500, 300, 200, 100, 50, 20, 10, 5, 2, 1, 0.5 or 0.2 microns. It may be particularly preferable for each of the thermally conductive particles to have a particle size of at least 1 micron. Alternatively or additionally, it may be particularly preferable for each of the thermally conductive particles to have a particle size of no more than 300 microns. Particles that are smaller than 1 micron may be difficult to control during manufacturing. Additionally, particles smaller than 1 micron may be more likely to pass through a filter in an aerosol-generating product containing an aerosol-forming substrate.Particles larger than 300 microns can occupy a significant amount of space in the substrate used for the aerosol-forming material. Therefore, it may be particularly advantageous for each heat-conducting particle to have a particle size of at least 1 micron, a particle size of no more than 300 microns, or both.

[0049] Optionally, each of the thermally conductive particles has three mutually perpendicular dimensions, wherein the largest dimension of the three dimensions is no more than 10, 8, 5, 3, or 2 times greater than the smallest dimension of the three dimensions. Optionally, each of the thermally conductive particles has three mutually perpendicular dimensions, wherein the largest dimension of the three dimensions is no more than 10, 8, 5, 3, or 2 times greater than the second largest dimension of the three dimensions. Optionally, each of the thermally conductive particles is substantially spherical. Advantageously, the orientation of the substantially spherical particles may not affect the thermal conductivity of the substrate as much as the orientation of non-spherical particles. Thus, the use of more spherical particles can lead to less variability between different substrates when the particle orientations are not controlled. In addition, substantially spherical particles can be more easily characterized.

[0050] Optionally, the heat-conducting particles comprise at least 10, 20, 50, 100, 200, 500, or 1000 particles. Advantageously, a larger number of particles in the aerosol-forming substrate can allow for more uniform thermal conductivity of the substrate.

[0051] Optionally, the substrate contains, on a dry weight basis, at least 20, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% by weight of thermally conductive particles. Optionally, the substrate contains, on a dry weight basis, no more than 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15% by weight of thermally conductive particles. Optionally, the substrate comprises, on a dry weight basis, 10 to 90, 20 to 90, 30 to 90, 40 to 90, 50 to 90, 60 to 90, 70 to 90, 80 to 90, 10 to 80, 20 to 80, 30 to 80, 40 to 80, 50 to 80, 60 to 80, 70 to 80, 10 to 70, 20 to 70, 30 to 70, 40 to 70, 50 to 70, 60 to 70, 10 to 60, 20 to 60, 30 to 60, 40 to 60, 50 to 60, 10 to 50, 20 to 50, 30 to 50, 40 to 50, 10 to 40, 20 to 40, 30 to 40, 10 to 30, 20 to 30, or 10 to 20% by weight of heat-conducting particles.It may be particularly preferred for the substrate to contain, on a dry weight basis, from 50 to 90, or more preferably from 60 to 90, or even more preferably from 65 to 85% by weight of heat-conducting particles.

[0052] A compromise may be necessary regarding the weight percentage of thermally conductive particles in a substrate. Increasing the weight percentage of particles in an aerosol-forming substrate can advantageously increase the substrate's thermal conductivity. However, increasing the weight percentage of particles in an aerosol-forming substrate can also reduce the available space for one or more of the aerosol-forming agent, binder, and fibers, thus resulting in a substrate that forms less aerosol or has lower tensile strength.

[0053] Optionally, the substrate contains, on a dry weight basis, at least 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55% by weight of an aerosol former. Optionally, the substrate contains, on a dry weight basis, no more than 55, 50, 45, 40, 35, 30, 25, 20, or 15% by weight of an aerosol former. Optionally, the substrate comprises, on a dry weight basis, from 7 to 60, from 10 to 60, from 20 to 60, from 30 to 60, from 40 to 60, from 50 to 60, from 7 to 50, from 10 to 50, from 20 to 50, from 30 to 50, from 40 to 50, from 7 to 40, from 10 to 40, from 20 to 40, from 30 to 40, from 7 and 30, from 10 to 30, from 20 to 30, from 7 to 20, from 10 to 20, or from 7 to 10% by weight of an aerosol former. It may be particularly preferred for the substrate to comprise, on a dry weight basis, from 15 to 25% by weight of an aerosol former.

[0054] Optionally, the aerosol forming substance comprises or consists of one or more of: polyhydric alcohols such as propylene glycol, polyethylene glycol, triethylene 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. Optionally, the aerosol forming substrate comprises one or both of glycerol and glycerol.

[0055] Optionally, the substrate contains, on a dry weight basis, at least 2, 4, 6, 8, 10, 12, 14, 16, or 18% by weight of fibers. Optionally, the substrate contains, on a dry weight basis, no more than 20, 18, 16, 14, 12, 10, 8, 6, or 4% by weight of fibers. Optionally, the substrate comprises, on a dry weight basis, from 4 to 20, from 6 to 20, from 8 to 20, from 10 to 20, from 12 to 20, from 14 to 20, from 16 to 20, from 18 to 20, from 2 to 18, from 4 to 18, from 6 to 18, from 8 to 18, from 10 to 18, from 12 to 18, from 14 to 18, from 16 to 18, from 2 to 16, from 4 to 16, from 6 to 16, from 8 to 16, from 10 to 16, from 12 to 16, from 14 to 16, from 2 to 14, from 4 to 14, from 6 to 14, from 8 to 14, from 10 to 14, 12 to 14, 2 to 12, 4 to 12, 6 to 12, 8 to 12, 10 to 12, 2 to 10, 4 to 10, 6 to 10, 8 to 10, 2 to 8, 4 to 8, 6 to 8, 2 to 6, 4 to 6, or 2 to 4 wt. % fibers. It may be particularly preferred for the substrate to contain, based on dry weight, 2 to 10 wt. % fibers.

[0056] The fibers are not necessarily cellulose fibers. Cellulose fibers are generally inexpensive and can increase the tensile strength of the substrate.

[0057] Optionally, each of the fibers has three mutually perpendicular dimensions, wherein the largest dimension of the three dimensions is at least 1.5, 2, 3, 5, 10, or 20 times greater than the smallest dimension of the three dimensions. Optionally, each of the fibers has three mutually perpendicular dimensions, wherein the largest dimension of the three dimensions is at least 1.5, 2, 3, 5, 10, or 20 times greater than the second largest dimension of the three dimensions.

[0058] Optionally, the substrate comprises, on a dry weight basis, at least 4, 6, or 8 weight % of a binder. Optionally, the substrate comprises, on a dry weight basis, no more than 8, 6, or 4 weight % of a binder. Optionally, the substrate comprises, on a dry weight basis, from 4 to 10, from 6 to 10, from 8 to 10, from 2 to 8, from 4 to 8, from 6 to 8, from 2 to 6, from 4 to 6, from 2 to 4 weight % of a binder. It may be particularly preferred for the substrate to comprise, on a dry weight basis, from 2 to 10 weight % of a binder.

[0059] Suitable binders are well known in the art and include, but are not limited to, natural pectins such as fruit, citrus or tobacco pectins; guar gums such as hydroxyethyl guar and hydroxypropyl guar; locust bean gums such as hydroxyethyl and hydroxypropyl locust bean gum; alginate; starches such as modified or derivatized starches; celluloses such as methyl, ethyl, ethyl hydroxymethyl and carboxymethyl cellulose; tamarind gum; dextran; pullalone; konjac flour; xanthan gum and the like. It may be particularly preferred for the binder to be or contain guar. It may be particularly preferred for the binder to comprise or consist of one or more of carboxymethylcellulose or hydroxypropylcellulose or a gum such as guar gum.

[0060] Optionally, the thermally conductive particles are substantially uniformly distributed throughout the aerosol-forming substrate. Optionally, the aerosol-forming substance is substantially uniformly distributed throughout the aerosol-forming substrate. Optionally, the fibers are substantially uniformly distributed throughout the aerosol-forming substrate. Optionally, the binder is substantially uniformly distributed throughout the aerosol-forming substrate. A substantially uniform distribution of the substrate components can result in the substrate having more spatially uniform properties. For example, substantially uniformly distributed thermally conductive particles can result in the substrate having substantially uniform thermal conductivity. As another example, a substantially uniformly distributed binder or fibers can result in the substrate having substantially uniform tensile strength.

[0061] Optionally, the substrate contains nicotine. Optionally, the substrate contains, on a dry weight basis, at least 0.01, 1, 2, 3, or 4 weight % nicotine. Optionally, the substrate contains, on a dry weight basis, no more than 5, 4, 3, 2, or 1 weight % nicotine. Optionally, the substrate contains, on a dry weight basis, from 0.01 to 5, from 1 to 5, from 2 to 5, from 3 to 5, from 4 to 5, from 0.01 to 4, from 1 to 4, from 2 to 4, from 3 to 4, from 0.01 to 3, from 1 to 3, from 2 to 3, from 0.01 to 2, from 1 to 2, from 0.01 to 1 weight % nicotine. It may be particularly preferable for the substrate to contain, on a dry weight basis, from 0.5 to 4% by weight of nicotine.

[0062] Nicotine is not necessarily distributed substantially uniformly throughout the aerosol-forming substrate.

[0063] Optionally, the substrate comprises an acid. Optionally, the substrate comprises, on a dry weight basis, at least 0.01, 1, 2, 3, or 4 weight % of acid. Optionally, the substrate comprises, on a dry weight basis, no more than 5, 4, 3, 2, or 1 weight % of acid. Optionally, the substrate comprises, on a dry weight basis, from 0.01 to 5, from 1 to 5, from 2 to 5, from 3 to 5, from 4 to 5, from 0.01 to 4, from 1 to 4, from 2 to 4, from 3 to 4, from 0.01 to 3, from 1 to 3, from 2 to 3, from 0.01 to 2, from 1 to 2, from 0.01 to 1 weight % of acid. It may be particularly advantageous for the substrate to contain, on a dry weight basis, from 0.5 to 5% by weight of acid.

[0064] Optionally, the acid comprises or consists of one or more of fumaric acid, lactic acid, benzoic acid, and levulinic acid.

[0065] Optionally, the acid is substantially uniformly distributed throughout the aerosol-forming substrate.

[0066] Optionally, the substrate comprises at least one plant material. Optionally, the substrate comprises, on a dry weight basis, at least 0.01, 1, 2, 5, 10, or 15 weight % of at least one plant material. Optionally, the substrate comprises, on a dry weight basis, no more than 20, 15, 10, 5, 2, or 1 weight % of at least one plant material. Optionally, the substrate comprises, based on dry weight, from 0.01 to 20, from 1 to 20, from 2 to 20, from 5 to 20, from 10 to 20, from 15 to 20, from 0.01 to 15, from 1 to 15, from 2 to 15, from 5 to 15, from 10 to 15, from 0.01 to 10, from 1 to 10, from 2 to 10, from 5 to 10, from 0.01 to 5, from 1 to 5, from 2 to 5, from 0.01 to 2, from 1 to 2, from 0.01 to 1 by weight of at least one plant material. It may be particularly preferred for the substrate to comprise, based on dry weight, from 1 to 15 by weight of at least one plant material.

[0067] Optionally, at least one plant material comprises or consists of one or both of cloves and rosemary.

[0068] Optionally, at least one plant material is substantially uniformly distributed throughout the aerosol-forming substrate.

[0069] Optionally, the substrate comprises at least one flavoring agent. Optionally, the substrate comprises, on a dry weight basis, at least 0.1, 1, 2, or 5 weight % of at least one flavoring agent. Optionally, the substrate comprises, on a dry weight basis, no more than 10, 5, 2, or 1 weight % of at least one flavoring agent. Optionally, the substrate comprises, on a dry weight basis, from 0.1 to 10, from 1 to 10, from 2 to 10, from 5 to 10, from 0.1 to 5, from 1 to 5, from 2 to 5, from 0.1 to 2, from 1 to 2, from 0.1 to 1 weight % of at least one flavoring agent. It may be particularly preferred for the substrate to comprise, on a dry weight basis, from 0.1 to 5 weight % of at least one flavoring agent.

[0070] Optionally, at least one flavoring agent is present as a coating, such as a coating on one or more other components of the aerosol-forming substrate. Alternatively or additionally, at least one flavoring agent is substantially uniformly distributed throughout the aerosol-forming substrate.

[0071] Optionally, the aerosol-forming substrate comprises at least one organic material, such as tobacco. Optionally, the at least one organic material comprises one or more of grass leaves, tobacco leaves, tobacco rib fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco. Optionally, the at least one organic material is substantially uniformly distributed throughout the aerosol-forming substrate.

[0072] The substrate may contain, on a dry weight basis, less than 10, 5, 3, 2, or 1% by weight of tobacco. Optionally, the aerosol-forming substrate is an aerosol-forming substrate that does not contain tobacco.

[0073] The tubular segment (part) of the aerosol-forming substrate can be described as a rod. Thus, a rod-shaped aerosol-forming substrate can be provided.

[0074] The aerosol-forming substrate is preferably in the form of a tube having an outer diameter, an inner diameter, and a length, wherein the length of the tube is from 5 mm to 100 mm, the outer diameter is from 3 mm to 20 mm, and the inner diameter is from 2.5 mm to 19.5 mm. The length of the tube can be from 8 mm to 25 mm, the outer diameter of the tube can be from 6 mm to 8 mm, and the inner diameter of the tube can be from 5 mm to 7.9 mm.

[0075] A current-collecting (susceptor) element can be located inside a rod of an aerosol-generating substrate. The current-collecting element can be an elongated current-collecting element. The current-collecting element can extend longitudinally inside the rod of the aerosol-generating substrate, for example, in contact with the inner surface of a tubular aerosol-generating substrate. The rod can have a substantially cylindrical shape, for example, a regular cylindrical shape. The current-collecting element can extend all the way to the downstream end of the rod of the aerosol-generating substrate. The current-collecting element can extend all the way to the upstream end of the rod of the aerosol-generating substrate. The current-collecting element can have substantially the same length as the rod of the aerosol-generating substrate.The current-collecting element may extend from the upstream end to the downstream end of the aerosol-forming substrate rod. The current-collecting element may be in the form of a pin, rod, strip, or plate. The current-collecting element may have a length of 5 to 15, 6 to 12, or 8 to 10 millimeters. The current-collecting element may have a width of 1 to 5 millimeters. The current-collecting element may have a thickness of 0.01 to 2, 0.5 to 2, or 0.5 to 1 millimeter.

[0076] The alternative aerosol-forming substrate or the rod of the aerosol-forming substrate may not contain current-collecting materials.

[0077] Optionally, some or each of the heat-conducting particles can be inductively heated, for example, to a temperature of at least 100, 150, or 200 degrees Celsius. Optionally, some or each of the heat-conducting particles comprises or consists of one or more current-receiving materials. This may advantageously allow the heat-conducting particles to be inductively heated. The heat-conducting particles may comprise or be the only current-receiving material(s) present in the aerosol-forming substrate or in the rod of the aerosol-forming substrate. That is, the aerosol-forming substrate or the rod of the aerosol-forming substrate may not contain current-receiving elements other than the heat-conducting or carbon particles.

[0078] Suitable current-collecting materials include, but are not limited to: carbon, carbon-based materials, graphene, graphite, expanded graphite, molybdenum, silicon carbide, stainless steels, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Suitable current-collecting materials may include a ferromagnetic material, such as ferritic iron, a ferromagnetic alloy such as ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. A suitable current-collecting material may be or contain aluminum. The current-collecting material preferably contains more than 5 percent, preferably more than 20 percent, more preferably more than 50 percent, or more than 90 percent of ferromagnetic or paramagnetic materials. Preferred current-collecting materials may comprise a metal, a metal alloy, or carbon.

[0079] In particular, preferred current-collecting materials may be or contain carbon, carbon-based materials, graphene, graphite, or expanded graphite. Advantageously, such materials have relatively high thermal conductivity, relatively low density, and can be inductively heated.

[0080] Optionally, the aerosol-forming substrate has a thermal conductivity of greater than 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.75, 1, 1.25, 1.5, 2, 5, 10, 20, 50, 100, 200 or 500 W / (m⋅K) in at least one direction at 25 degrees Celsius.

[0081] The optional aerosol-forming substrate has a density of not more than 1500, 1450, 1400, 1350, 1300, 1250, 1200, 1100, 1050, 1000, 950, 900, 850, 800, 850, 800, 750, 700, 650, or 600 kg / m3 3 . The optional aerosol-forming substrate has a density of 600 to 1400, 800 to 1200, or 900 to 1100 kg / m3 3. Mainly, decreasing the substrate density can reduce the costs of substrate transportation.

[0082] The optionally aerosol-forming substrate has a moisture content of 1 to 20% by weight, or 3 to 15% by weight. This moisture content can be measured after 4 to 8 hours of equilibration at 50% relative humidity at 20 degrees Celsius. The optionally aerosol-forming substrate contains 1 to 20% by weight, or 3 to 15% by weight, of water. The moisture or water content of the substrate can be measured using the titration method. The moisture or water content of the substrate can be measured using the Karl Fischer method.

[0083] Optionally, the aerosol-forming substrate is formed from a sheet of aerosol-forming material that is folded to form a tubular segment (portion). Thus, the hollow tubular segment may be a folded sheet of aerosol-forming material, such as a folded sheet of homogenized tobacco material or, for example, a folded sheet of a non-tobacco-containing aerosol-forming material.

[0084] The aerosol-forming substrate may have a thickness equivalent to one layer of a sheet of aerosol-forming material. The aerosol-forming substrate may have a thickness equivalent to two or more layers of the sheet. The sheet of aerosol-forming material may have a thickness of at least 5, 10, 20, 50, 100, 150, or 200 microns. Optionally, the sheet or strip may have a thickness of no more than 2000, 1000, 500, 400, 300, or 250 microns. Optionally, the sheet may have a thickness of 100 to 350 or 150 to 300 microns.

[0085] Optionally, the sheet of aerosol-forming material has a grammage of at least 20, 50 or 100 g / m 2 It is not necessary that the sheet or strip has a grammage of no more than 300 g / m 2 The sheet does not necessarily have a grammage of 20 to 300, 50 to 250, or 100 to 250 g / m 2 .

[0086] Optionally, the sheet has a density of at least 0.1, 0.2, 0.3 or 0.5 g / m 3 The sheet does not necessarily have a density of more than 2, 1.5, 1.2 or 1 g / m 3 . Optionally, the sheet has a density of from 0.1 to 2, from 0.2 to 2, from 0.3 to 2, from 0.3 to 1.5, or from 0.3 to 1.2 g / m 3 .

[0087] The hollow tubular segment (part) may be an extruded tube of an aerosol-forming material, such as an extruded tube of homogenized tobacco material or, for example, an extruded tube of an aerosol-forming material that does not contain tobacco.

[0088] The aerosol-generating article may be in the form of a rod and may contain a plurality of components, including an aerosol-forming substrate, assembled within a wrapper or shell.

[0089] Optionally, the aerosol-generating article comprises a front rod. Optionally, the aerosol-generating article comprises a first hollow tube, such as a first hollow acetate tube. Optionally, the aerosol-generating article comprises a second hollow tube, such as a second hollow acetate tube. Optionally, the second hollow tube comprises one or more ventilation openings. Optionally, the aerosol-generating article comprises a mouthpiece filter rod. Optionally, the aerosol-generating article comprises a wrapper, such as a paper wrapper.

[0090] Optionally, the front rod is located at the upstream end of the article. Optionally, the aerosol-forming substrate is located downstream of the front rod. Optionally, the first hollow tube is located downstream of the aerosol-forming substrate. Optionally, the second hollow tube is located downstream of the first hollow tube. Optionally, a mouthpiece filter rod is located downstream of one or both of the first hollow tube and the second hollow tube. Optionally, the mouthpiece filter rod is located at the downstream end of the article. Optionally, the downstream end of the article, which may be referred to as the mouthpiece end of the article, can be configured for insertion into the user's mouth. The user can inhale, for example, directly using the mouthpiece end of the article.

[0091] Optionally, the front rod, the tubular aerosol-forming substrate, one or both of the first hollow tube and the second hollow tube, and the mouthpiece filter rod are surrounded by a wrapper, such as a paper wrapper.

[0092] Optionally, the front rod has a length of 2 to 10, 3 to 8, or 4 to 6 mm, for example, about 5 mm. Optionally, the aerosol-forming substrate has a length of 5 to 20, 8 to 15, or 10 to 15 mm, for example, about 12 mm. Optionally, the first hollow tube has a length of 2 to 20, 5 to 15, or 5 to 10 mm, for example, about 8 mm. Optionally, the second hollow tube has a length of 2 to 20, 5 to 15, or 5 to 10 mm, for example, about 8 mm. Optionally, the mouthpiece filter rod has a length of 5 to 20, 8 to 15, or 10 to 15 mm, for example, about 12 mm. The lengths of one or more of the front rod forming the substrate aerosol, the first hollow tube, the second hollow tube and the mouthpiece filter rod may extend in a longitudinal direction.

[0093] One or more of the front rod forming the substrate aerosol, the first hollow tube, the second hollow tube and the mouthpiece filter rod may substantially have a cylindrical shape, for example, a regular cylindrical shape.

[0094] According to one aspect of the present invention, an aerosol generating system is provided.

[0095] The system may comprise an aerosol-generating article and an electrical device that generates the aerosol. The article may be the article described above, for example, the article according to the third aspect.

[0096] Optionally, the electrical aerosol generating device is configured to resistively heat the aerosol generating article when used.

[0097] Optionally, the electrical aerosol generating device is configured to inductively heat an aerosol generating article, such as an aerosol-forming substrate of the aerosol generating article, when used.

[0098] According to the present invention, a method for forming a hollow tubular aerosol-forming substrate, for example, a substrate for an aerosol-generating article, as described above, is provided. The method may include forming a suspension containing one or more, or all, of thermally conductive particles, an aerosol-forming substance, fibers, and a binder. The method may include casting and drying the suspension to form an aerosol-forming substrate, or extruding the suspension to form an aerosol-forming substrate, or casting and drying the suspension to form a precursor, such as a sheet of aerosol-forming material, and then shaping the precursor into an aerosol-forming substrate.

[0099] Optionally, the suspension contains water. Optionally, the suspension contains 20 to 90, 30 to 90, 40 to 90, 40 to 85, 50 to 80, 60 to 80, or 60 to 75% by weight of water.

[0100] Optionally, the suspension contains an acid. Optionally, the acid comprises or consists of one or more of fumaric acid, lactic acid, benzoic acid, and levulinic acid.

[0101] The suspension may not contain nicotine.

[0102] Optionally, forming a suspension includes forming a first mixture. The first mixture may contain an aerosol-forming agent. The first mixture may contain fibers. The first mixture may contain water. The first mixture may contain an acid. The first mixture may contain nicotine. Forming a suspension may include forming a second mixture. The second mixture may contain heat-conducting particles. The second mixture may contain a binder. Forming a suspension may include adding the second mixture to the first mixture to form a combined mixture.

[0103] Thus, the formation of a suspension may include:

[0104] forming a first mixture comprising an aerosol forming agent, fibers, water, optionally an acid, and optionally nicotine;

[0105] forming a second mixture containing heat-conducting particles and a binder;

[0106] and adding the second mixture to the first mixture to form a combined mixture.

[0107] The combined mixture may then be formed into a suspension, for example, by mixing.

[0108] Optionally, forming the first mixture includes providing an aerosol forming substance or a solution containing an aerosol forming substance and nicotine.

[0109] Optionally, forming the first mixture includes adding an acid to the aerosol forming substance or a solution containing the aerosol forming substance and nicotine to form a first pre-mixture.

[0110] Optionally, forming the first mixture includes adding water to the aerosol forming substance or the solution containing the aerosol forming substance and nicotine, or to the first premixture, to form a second premixture.

[0111] Optionally, forming the first mixture includes adding fibers to the second pre-mixture.

[0112] Optionally, forming the second mixture includes mixing the heat-conducting particles and the binder.

[0113] Optionally, the method, for example, the step of forming a suspension, includes first mixing the combined mixture. Optionally, the first mixing occurs at a first pressure of no more than 500, 400, 300, 250, or 200 mbar. Optionally, the first mixing occurs for 1 to 10, 2 to 8, or 3 to 6 minutes, for example, for approximately 4 minutes.

[0114] Optionally, the method, for example, the step of forming a suspension, includes a second mixing after the first mixing. Optionally, the second mixing occurs at a second pressure that is less than the first pressure. Optionally, the second pressure is no more than 500, 400, 300, 200, 150, or 100 mbar. Optionally, the second mixing occurs for 5 to 120, 5 to 80, 5 to 40, or 10 to 30 seconds, for example, approximately 20 seconds.

[0115] Optionally, slurry casting includes casting the slurry onto a flat support, such as a steel flat support.

[0116] Optionally, after casting the slurry and before drying the slurry, the method includes setting the thickness of the slurry, for example, setting the thickness of the slurry to a value of 100 to 1200, 200 to 1000, 300 to 900, 500 to 700 microns, such as approximately 600 microns.

[0117] Optionally, drying the slurry includes providing a gas stream, such as air, over or past the slurry. Optionally, the gas stream is heated. Optionally, the gas stream is heated to a temperature of 100 to 160 or 120 to 140 degrees Celsius. Optionally, the gas stream is provided for 1 to 10 or 2 to 5 minutes. Optionally, drying the slurry includes drying the slurry until the moisture content of the slurry is 1 to 20, 2 to 15, 2 to 10, or 3 to 7 weight percent.

[0118] Optionally, drying the suspension results in the formation of a precursor for forming an aerosol-forming substrate therefrom, wherein the precursor is a sheet of aerosol-forming material. Optionally, the method comprises cutting the sheet of aerosol-forming material.

[0119] A sheet of aerosol-forming material can be formed into the shape of an aerosol-forming substrate by rolling a web of the aerosol-forming substrate into a tube. The walls of the tube are thus formed from the sheet of aerosol-forming material. The tubular shape can be maintained by overlapping a portion of the rolled sheet and securing the overlapped portion with an adhesive such as gum. The walls of the tube formed by rolling the sheet of aerosol-forming material can have a thickness equal to that of the sheet of aerosol-forming material; that is, the tube can be formed from a single layer of the sheet of aerosol-forming material. However, the walls of the tube can be formed from multiple layers of the sheet rolled into a tube shape. After rolling and securing, the tube of aerosol-forming material can be cut into lengths to form tubular segments (parts) of the aerosol-forming substrate.

[0120] As will be apparent to one skilled in the art after reading this description, features described herein with respect to one aspect may be applicable to any other aspect.

[0121] As used herein, the term "aerosol-forming substrate" may refer to a substrate capable of releasing an aerosol or volatile compounds capable of forming an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may comprise an aerosol-forming material. The aerosol-forming substrate may be applied to a substrate or support by adsorption, coating, impregnation, or other means. For convenience, the aerosol-forming substrate may be part of an aerosol-generating article or smoking article.

[0122] In the context of this document, the term "thermally conductive particles" may refer to particles having a thermal conductivity that is greater than 0.3, preferably 0.5, or more preferably 1 W / (m⋅K) in at least one direction at 25 degrees Celsius, for example, in all directions at 25 degrees Celsius. The particles may be characterized by anisotropic or isotropic thermal conductivity.

[0123] In the context of this document, the term "expanded graphite" may refer to a graphite-based material or a material with a graphite-like structure. Expanded graphite may have carbon layers (similar to graphite, for example) with spaces between the carbon layers that are larger than the spaces found between the carbon layers in ordinary graphite. Expanded graphite may have carbon layers with elements or compounds incorporated into the spaces between the carbon layers.

[0124] In the context of this document, the term "particle size" may refer to a single quantity and may be used to describe the size of a given particle. The quantity may represent the diameter of a spherical particle occupying the same volume as the given particle. All particle sizes and particle size distributions in this document can be obtained using a standard laser diffraction method. The particle sizes and particle size distributions as described in this document can be obtained using a commercially available sensor, such as the Sympatec HELOS laser diffraction sensor.

[0125] In the context of this document, unless otherwise specified, the term "density" may be used to refer to true density. Thus, unless otherwise specified, the density of a powder or plurality of particles may refer to the true density of the powder or plurality of particles (rather than the bulk density of the powder or plurality of particles, which may vary depending on how the powder or plurality of particles is handled). True density can be measured using a number of standard methods, with these methods often based on Archimedes' principle. The most widely used method for measuring the true density of a powder involves placing the powder in a container (pycnometer) of known volume and weighing it. The pycnometer is then filled with a fluid of known density, with the powder being insoluble.The volume of powder is determined by the difference between the volume shown by the pycnometer and the volume of liquid added (that is, the volume of air displaced).

[0126] As used herein, the term "aerosol-generating article" may refer to an article that is capable of generating or releasing an aerosol, such as by heating.

[0127] As used herein, the term "longitudinal" may refer to a direction extending between a downstream or near end and an upstream or far end of a component, such as an aerosol-forming substrate or an aerosol-generating article.

[0128] In the context of this document, the term "transverse" may refer to a direction that is perpendicular to the longitudinal direction.

[0129] As used in this document, the term "aerosol generating device" may refer to a device for use with an aerosol generating article to enable the generation or release of an aerosol.

[0130] As used herein, the term "sheet" may refer to a generally flat, layered member having a width and length that are substantially greater, such as at least 2, 3, 5, 10, 20, or 50 times, than its thickness.

[0131] As used herein, the term "aerosol former" may refer to any suitable known compound or mixture of compounds that, when used, facilitates the formation of an aerosol. The aerosol may be a dense and stable aerosol. The aerosol may be substantially resistant to thermal degradation at the operating temperature of the aerosol-forming substrate or aerosol-generating article.

[0132] As used herein, the term "aerosol cooling element" may refer to a component of an aerosol-generating article that is positioned downstream of an aerosol-forming substrate such that, in use, an aerosol formed by the substrate or volatile compounds released from the aerosol-forming substrate passes through the aerosol cooling element and is cooled by it prior to inhalation by the user.

[0133] As used herein, the term "rod" may refer to a substantially cylindrical, such as a true cylindrical, member with a substantially circular, oval, or elliptical cross-section.

[0134] In the context of this document, the term "ventilation level" may refer to the volumetric ratio between the airflow into the aerosol-generating product through the ventilation zone (ventilation airflow) and the sum of the aerosol-containing airflow and the ventilation airflow. The higher the ventilation level, the greater the dilution of the aerosol flow delivered to the consumer.

[0135] The present invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0136] Exi. An aerosol-generating article for producing an inhalable aerosol, wherein the aerosol-generating article comprises a hollow tubular aerosol-forming substrate, wherein the aerosol-forming substrate comprises a plurality of heat-conducting particles and an aerosol-forming substance.

[0137] Ex1. An aerosol-generating article for producing an inhalable aerosol upon heating, wherein the aerosol-generating article comprises a plurality of components, including an aerosol-forming substrate, wherein the aerosol-forming substrate has the shape of a hollow tubular portion, forming a substrate cavity, passing between an upstream end of the aerosol-forming substrate and a downstream end of the aerosol-forming substrate, in which the aerosol-forming substrate contains a plurality of heat-conducting particles and an aerosol-forming substance.

[0138] Ex2. An aerosol-generating article according to example Exi or Ex1, wherein each of the plurality of thermally conductive particles has a thermal conductivity greater than 1, 2, 5, 10, 20, 50, 100, 200, 500, or 1000 W / (m⋅K).

[0139] Ex3. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate comprises, on a dry weight basis: from 5 to 95 wt.%, such as from 10 to 90 wt.%, of thermally conductive particles, wherein each thermally conductive particle of the thermally conductive particles has a thermal conductivity of at least 1 W / (m⋅K) in at least one direction at 25 degrees Celsius.

[0140] Ex4. An aerosol-generating article according to Example Ex3, wherein the aerosol-forming substrate further comprises from 7 to 60% by weight of an aerosol-forming substance; from 2 to 20% by weight of fibers; and from 2 to 10% by weight of a binder.

[0141] Ex5. An aerosol-generating article according to example Ex3 or Ex4, wherein the aerosol-forming substrate has a thermal conductivity of at least 0.12 W / (m⋅K), such as at least 0.14 W / (m⋅K), such as at least 0.22 W / (m⋅K) in at least one direction at 25 degrees Celsius.

[0142] Ex6. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate comprises, on a dry weight basis: from 10 to 90% by weight of thermally conductive particles; from 7 to 60% by weight of an aerosol forming agent; from 2 to 20% by weight of fibers; and from 2 to 10% by weight of a binder, wherein each of the thermally conductive particles consists of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond.

[0143] Ex 7. An aerosol-generating article according to any preceding example, wherein each thermally conductive particle of the plurality of thermally conductive particles has a thermal conductivity of at least 0.3, 0.5, 1, 2, 5, or 10 W / (m⋅K) in at least one direction, such as when measured at 25 degrees Celsius.

[0144] Ex 8. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles comprise carbon, such as at least 10, 30, 50, 70, 90, 95, 98, or 99% by weight carbon.

[0145] Ex 9. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles are graphite particles, or some or all of the heat-conducting particles are expanded graphite particles, or some of the heat-conducting particles are graphite particles and some of the heat-conducting particles are expanded graphite particles.

[0146] Ex 10. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles are diamond particles, such as synthetic diamond particles.

[0147] Ex 11. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles are graphene particles.

[0148] Ex 12. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles are carbon nanotubes.

[0149] Ex 13. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles are charcoal particles.

[0150] Ex 14. An aerosol-generating article according to any preceding example, in which some or all of the heat-conducting particles comprise metal.

[0151] Ex 15. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles comprise one or both of copper and aluminum.

[0152] Ex 16. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles comprise an alloy.

[0153] Ex 17. An aerosol-generating article according to any preceding example, wherein some or all of the heat-conducting particles comprise an intermetallic compound.

[0154] Ex 18. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D10 particle size by number, wherein the D10 particle size by number is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0155] Ex 19. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D10 particle size by number, wherein the D10 particle size by number is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0156] Ex 20. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D50 particle size by number, wherein the D50 particle size by number is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0157] Ex 21. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D50 particle size by number, wherein the D50 particle size by number is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0158] Ex 22. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D90 particle size by number, wherein the D90 particle size by number is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0159] Ex 23. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D90 particle size by number, wherein the D90 particle size by number is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0160] Ex 24. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a D10 particle size distribution by volume, wherein the D10 particle size by volume is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0161] Ex 25. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D10 particle size by volume, wherein the D10 particle size by volume is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0162] Ex 26. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a D50 particle size distribution by volume, wherein the D50 particle size by volume is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0163] Ex 27. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D50 particle size by volume, wherein the D50 particle size by volume is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0164] Ex 28. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D90 particle size by volume, wherein the D90 particle size by volume is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0165] Ex 29. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution with a D90 particle size by volume, wherein the D90 particle size by volume is not more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0166] Ex 30. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution of a D10 particle size by number, a D90 particle size by number, a D10 particle size by volume, and a D90 particle size by volume, wherein: the D90 particle size by number is not more than 50, 40, 30, 20, 10, or 5 times the D10 particle size by number, or the D10 particle size by volume is not more than 50, 40, 30, 20, 10, or 5 times the D10 particle size by volume, or both the D90 particle size by number is not more than 50, 40, 30, 20, 10, or 5 times the D10 particle size by number and the D10 particle size by volume is not more than 50, 40, 30, 20, 10 or 5 times the D10 particle size by volume.

[0167] Ex 31. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution and one or both of the D10 particle size by number and the D10 particle size by volume is from 1 to 20 microns.

[0168] Ex 32. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles have a particle size distribution wherein one or both of the D90 particle size by number and the D90 particle size by volume is from 50 to 300 microns or from 50 to 200 microns.

[0169] Ex 33. An aerosol-generating article according to any preceding example, wherein each of the thermally conductive particles has a particle size of at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0170] Ex 34. An aerosol-generating article according to any preceding example, wherein each of the heat-conducting particles has a particle size of no more than 1000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0171] Ex 35. An aerosol-generating article according to any preceding example, wherein each of the heat-conducting particles has three mutually perpendicular dimensions, the largest dimension of the three dimensions being no more than 10, 8, 5, 3, or 2 times greater than one or both of the smallest dimension of the three dimensions and the second largest dimension of the three dimensions.

[0172] Ex 36. An aerosol-generating article according to any preceding example, wherein each of the heat-conducting particles is substantially spherical.

[0173] Ex 37. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles comprise at least 10, 20, 50, 100, 200, 500, or 1000 particles.

[0174] Ex 38. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, at least 20, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% by weight of heat-conducting particles.

[0175] Ex 39. An aerosol-generating article according to any preceding example, wherein the substrate contains, on a dry weight basis, not more than 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15% by weight of heat-conducting particles.

[0176] Ex 40. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, from 10 to 90, from 20 to 90, from 30 to 90, from 40 to 90, from 50 to 90, from 60 to 90, from 70 to 90, from 80 to 90, from 10 to 80, from 20 to 80, from 30 to 80, from 40 to 80, from 50 to 80, from 60 to 80, from 70 to 80, from 10 to 70, from 20 to 70, from 30 to 70, from 40 to 70, from 50 to 70, from 60 to 70, from 10 to 60, 20 to 60, 30 to 60, 40 to 60, 50 to 60, 10 to 50, 20 to 50, 30 to 50, 40 to 50, 10 to 40, 20 to 40, 30 to 40, 10 to 30, 20 to 30, or 10 to 20% by weight of heat-conducting particles.

[0177] Ex 41. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, at least 10, 15, 20, 25, 30, 35, 40, 45, 50 or 55% by weight of an aerosol-forming substance.

[0178] Ex 42. An aerosol-generating article according to any preceding example, wherein the substrate contains, on a dry weight basis, not more than 55, 50, 45, 40, 35, 30, 25, 20 or 15% by weight of an aerosol-forming substance.

[0179] Ex 43. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, from 7 to 60, from 10 to 60, from 20 to 60, from 30 to 60, from 40 to 60, from 50 to 60, from 7 to 50, from 10 to 50, from 20 to 50, from 30 to 50, from 40 to 50, from 7 to 40, from 10 to 40, from 20 to 40, from 30 to 40, from 7 to 30, from 10 to 30, from 20 to 30, from 7 to 20, from 10 to 20, or from 7 to 10 by weight. % of aerosol forming substance, particularly preferably from 15 to 25 wt. % of aerosol forming substance.

[0180] Ex 44. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substance comprises or consists of one or more of: polyhydric alcohols such as propylene glycol, polyethylene glycol, triethylene 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.

[0181] Ex 45. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate comprises one or both of glycerin and glycerol.

[0182] Ex 46. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, at least 2, 4, 6, 8, 10, 12, 14, 16 or 18% by weight of fibres.

[0183] Ex 47. An aerosol-generating article according to any preceding example, wherein the substrate contains, on a dry weight basis, not more than 20, 18, 16, 14, 12, 10, 8, 6 or 4% by weight of fibres.

[0184] Ex 48. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, from 4 to 20, from 6 to 20, from 8 to 20, from 10 to 20, from 12 to 20, from 14 to 20, from 16 to 20, from 18 to 20, from 2 to 18, from 4 to 18, from 6 to 18, from 8 to 18, from 10 to 18, from 12 to 18, from 14 to 18, from 16 to 18, from 2 to 16, from 4 to 16, from 6 to 16, from 8 to 16, from 10 to 16, from 12 to 16, from 14 to 16, from 2 to 14, from 4 to 14, from 6 to 14, from 8 to 14, from 10 to 14, from 12 to 14, from 2 to 12, from 4 to 12, from 6 to 12, from 8 to 12, from 10 to 12, from 2 to 10, from 4 to 10, from 6 to 10, from 8 to 10, from 2 to 8, from 4 to 8, from 6 to 8, from 2 to 6, from 4 to 6, or from 2 to 4 weight % of fibers, particularly preferably from 2 to 10 weight % of fibers.

[0185] Ex 49. An aerosol-generating article according to any preceding example, wherein the fibres are cellulose fibres.

[0186] Ex 50. An aerosol-generating article according to any preceding example, wherein each of the fibres has three mutually perpendicular dimensions, the largest dimension of the three dimensions being at least 1.5, 2, 3, 5, 10 or 20 times larger than the smallest dimension of the three dimensions.

[0187] Ex 51. An aerosol-generating article according to any preceding example, wherein each of the fibres has three mutually perpendicular dimensions, the largest dimension of the three dimensions being at least 1.5, 2, 3, 5, 10 or 20 times larger than the second largest dimension of the three dimensions.

[0188] Ex 52. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, at least 4, 6 or 8 wt.% binder.

[0189] Ex 53. An aerosol-generating article according to any preceding example, wherein the substrate contains, on a dry weight basis, not more than 8, 6 or 4 weight % binder.

[0190] Ex 54. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, from 4 to 10, from 6 to 10, from 8 to 10, from 2 to 8, from 4 to 8, from 6 to 8, from 2 to 6, from 4 to 6, from 2 to 4 wt. % binder, particularly preferably from 2 to 10 wt. % binder.

[0191] Ex 55. An aerosol-generating article according to any preceding example, wherein the binder comprises or consists of one or more of carboxymethylcellulose or hydroxypropylcellulose.

[0192] Ex 56. An aerosol-generating article according to any preceding example, wherein the binder comprises or consists of one or more gums, such as guar gum.

[0193] Ex 57. An aerosol-generating article according to any preceding example, wherein the heat-conducting particles are substantially uniformly distributed throughout the aerosol-forming substrate.

[0194] Ex 58. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substance is substantially uniformly distributed throughout the aerosol-forming substrate.

[0195] Ex 59. An aerosol-generating article according to any preceding example, wherein the fibers are substantially uniformly distributed throughout the aerosol-forming substrate.

[0196] Ex 60. An aerosol-generating article according to any preceding example, wherein the binder is substantially uniformly distributed throughout the aerosol-forming substrate.

[0197] Ex 61. An aerosol-generating article according to any preceding example, wherein the substrate comprises nicotine.

[0198] Ex 62. An aerosol-generating article according to example Ex 61, wherein the substrate contains, on a dry weight basis, at least 0.01, 1, 2, 3 or 4% by weight of nicotine.

[0199] Ex 63. An aerosol-generating article according to any of Ex 61 to Ex 62, wherein the substrate contains, on a dry weight basis, no more than 5, 4, 3, 2 or 1% by weight of nicotine.

[0200] Ex 64. An aerosol-generating article according to any preceding example, wherein the substrate comprises, on a dry weight basis, from 0.01 to 5, from 1 to 5, from 2 to 5, from 3 to 5, from 4 to 5, from 0.01 to 4, from 1 to 4, from 2 to 4, from 3 to 4, from 0.01 to 3, from 1 to 3, from 2 to 3, from 0.01 to 2, from 1 to 2, from 0.01 to 1% by weight of nicotine, particularly preferably from 0.5 to 4% by weight of nicotine.

[0201] Ex 65. An aerosol-generating article according to any of Ex 61 to Ex 63, wherein the nicotine is substantially uniformly distributed throughout the aerosol-forming substrate.

[0202] Ex 66. An aerosol-generating article according to any preceding example, wherein the substrate comprises an acid.

[0203] Ex 67. An aerosol generating article according to example Ex 66, wherein the substrate contains, based on dry weight, at least 0.01, 1 or 2% by weight of acid.

[0204] Ex 68. An aerosol-generating article according to any of Ex 66 to Ex 67, wherein the substrate contains, based on dry weight, not more than 3, 2 or 1% by weight of acid.

[0205] Ex 69. An aerosol generating article according to any of the examples Ex 66 to Ex 68, wherein the substrate contains, on a dry weight basis, from 0.01 to 3, from 1 to 3, from 2 to 3, from 0.01 to 2, from 1 to 2, from 0.01 to 1 weight % of acid, particularly preferably from 0.5 to 5 weight % of acid.

[0206] Ex 70. An aerosol-generating article according to any of Ex 66 to Ex 69, wherein the acid comprises or consists of one or more of fumaric acid, lactic acid, benzoic acid and levulinic acid.

[0207] Ex 71. An aerosol-generating article according to any of Ex 66 to Ex 70, wherein the acid is substantially uniformly distributed throughout the aerosol-forming substrate.

[0208] Ex 72. An aerosol-generating article according to any preceding example, wherein the substrate comprises at least one plant material.

[0209] Ex 73. An aerosol-generating article according to example Ex 72, wherein the substrate comprises, on a dry weight basis, at least 0.01, 1, 2, 5, 10 or 15% by weight of at least one plant material.

[0210] Ex 74. An aerosol-generating article according to any of Ex 72 to Ex 73, wherein the substrate contains, on a dry weight basis, no more than 20, 15, 10, 5, 2 or 1% by weight of at least one plant material.

[0211] Ex 75. An aerosol-generating article according to any of Ex 72 to Ex 74, wherein the substrate comprises, on a dry weight basis, from 0.01 to 20, from 1 to 20, from 2 to 20, from 5 to 20, from 10 to 20, from 15 to 20, from 0.01 to 15, from 1 to 15, from 2 to 15, from 5 to 15, from 10 to 15, from 0.01 to 10, from 1 to 10, from 2 to 10, from 5 to 10, from 0.01 to 5, from 1 to 5, from 2 to 5, from 0.01 to 2, from 1 to 2, from 0.01 to 1 by weight. % of at least one plant material, particularly preferably from 1 to 15 wt. % of at least one plant material.

[0212] Ex 76. An aerosol-generating article according to any of the examples Ex 72 to Ex 75, wherein at least one plant material comprises or consists of one or both of clove and rosemary.

[0213] Ex 77. An aerosol-generating article according to any of the examples Ex 72 to Ex 76, wherein the at least one plant material is substantially uniformly distributed throughout the aerosol-forming substrate.

[0214] Ex 78. An aerosol-generating article according to any preceding example, wherein the substrate comprises at least one flavoring agent.

[0215] Ex 79. An aerosol-generating article according to example Ex 78, wherein the substrate contains, based on dry weight, at least 0.1, 1, 2 or 5% by weight of at least one flavoring agent.

[0216] Ex 80. An aerosol-generating article according to any of Ex 78 to Ex 7 9, wherein the substrate contains, on a dry weight basis, no more than 10, 5, 2 or 1 weight % of at least one flavouring agent.

[0217] Ex 81. An aerosol-generating article according to any of the examples Ex 78 to Ex 80, wherein the substrate comprises, based on dry weight, from 0.1 to 10, from 1 to 10, from 2 to 10, from 5 to 10, from 0.1 to 5, from 1 to 5, from 2 to 5, from 0.1 to 2, from 1 to 2, from 0.1 to 1 weight % of at least one flavoring agent, particularly preferably from 0.1 to 5 weight % of at least one flavoring agent.

[0218] Ex 82. An aerosol-generating article according to any of the examples Ex 78 to Ex 81, wherein at least one flavoring agent is present as a coating, such as a coating on one or more other components of the aerosol-forming substrate.

[0219] Ex 83. An aerosol-generating article according to any of the examples Ex 78 to Ex 82, wherein at least one flavoring agent is substantially uniformly distributed throughout the aerosol-forming substrate.

[0220] Ex 84. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate comprises one or more organic materials such as tobacco.

[0221] Ex 85. An aerosol-generating article according to any preceding example, wherein the organic material comprises one or more of grass leaves, tobacco leaves, tobacco rib fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco.

[0222] Ex 86. An aerosol-generating article according to any preceding example, wherein the organic materials are substantially uniformly distributed throughout the aerosol-forming substrate.

[0223] Ex 87. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate is an aerosol-forming substrate that does not contain tobacco, for example wherein the aerosol-forming substrate does not contain tobacco.

[0224] Ex 88. An aerosol-generating article according to any preceding example, wherein some or each of the heat-conducting particles comprises a current-receiving material and / or is formed from a current-receiving material, such as a carbon current-receiving material.

[0225] Ex 89. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a thermal conductivity of at least 0.15, 0.2, 0.22, 0.3, 0.4, 0.5, 0.75, 1, 1, 25, or 1.5 W / (m⋅K) in at least one direction or in all directions at 25 degrees Celsius.

[0226] Ex 90. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a density of less than 1500, 1050, 1000, 950, 900, 850, 800, 850, 800, 750, 700, or 650 kg / m3.

[0227] Ex 91. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a density of from 500 to 900 or from 600 to 800 kg / m3 3 .

[0228] Ex 92. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a moisture content of from 1 to 20 or from 3 to 15% by weight.

[0229] Ex 93. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate contains from 1 to 20 or from 3 to 15% by weight of water.

[0230] Ex 94. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a density of at least 0.1, 0.2, 0.3, or 0.5 g / m3 3 .

[0231] Ex 95. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a density of not more than 2, 1.5, 1.2 or 1 g / m3 3 .

[0232] Ex 96. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a density of from 0.1 to 2, from 0.2 to 2, from 0.3 to 2, from 0.3 to 1.5, or from 0.3 to 1.2 g / m 3 .

[0233] Ex97. An aerosol-generating article according to any preceding example, wherein the substrate is in the form of a tube having a width in a radial dimension and a length in a longitudinal dimension, the length being from 5 mm to 100 mm, such as from 6 mm to 80 mm, such as from 7 mm to 60 mm, such as from 8 mm to 55 mm, such as from 9 mm to 50 mm, such as from 10 mm to 45 mm, such as from 11 mm to 35 mm, such as from 12 mm to 25 mm.

[0234] Ex98. An aerosol generating article according to any preceding example, wherein the substrate is in the form of a tube having a width in a radial dimension and a length in a longitudinal dimension, wherein the width is determined by the outer diameter of the tube, the outer diameter being from 3 mm to 20 mm, such as from 4 mm to 12 mm, such as from 4.5 mm to 10 mm, such as from 5 mm to 9 mm, such as from 6 mm to 8 mm, such as from 6.5 mm to 7.5 mm, such as approximately 7 mm.

[0235] Ex99. An aerosol-generating article according to any preceding example, wherein the substrate is in the form of a tube having an outer diameter and an inner diameter, wherein the inner diameter is from 2.5 mm to 19 mm, such as from 3.5 mm to 11.5 mm, such as from 4 mm to 9 mm, such as from 4.5 mm to 8.5 mm, such as from 5.5 mm to 7.5 mm, such as from 6.9 mm to 7.3 mm, such as approximately 7 mm.

[0236] Ex100. An aerosol-generating article according to any preceding example, wherein the substrate is in the form of a tube having a length, an outer diameter, and an inner diameter, wherein the wall thickness of the tube is determined by the difference between the outer diameter and the inner diameter, wherein the wall thickness is from 100 microns to 5 mm, such as from 150 microns to 3 mm, such as from 200 microns to 2 mm, such as from 250 microns to 1.5 mm, such as from 300 microns to 1 mm, such as from 350 microns to 500 microns.

[0237] Ex101. An aerosol-generating article according to any preceding example, wherein the substrate is in the form of a tube and the tube is a rolled sheet of aerosol-forming material, such as a rolled sheet of homogenized tobacco material, such as a rolled sheet of molded leaf tobacco, or, for example, a rolled sheet of aerosol-forming material that does not contain tobacco.

[0238] Ex102. An aerosol-generating article according to any of the examples of Exi-Ex 100, wherein the substrate is in the form of a tube and the tube is an extruded tube of an aerosol-generating material, such as an extruded tube of homogenized tobacco material or, for example, an extruded tube of a non-tobacco aerosol-generating material.

[0239] Ex 103. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article comprises a front rod, such as wherein the front rod has a length of 2 mm to 10 mm, 3 mm to 8 mm, or 4 mm to 6 mm, such as approximately 5 mm.

[0240] Ex 104. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article comprises a first hollow support tube, such as a first hollow acetate tube, such as wherein the first hollow support tube is located downstream of the aerosol-forming substrate within the aerosol-generating article.

[0241] Ex 105. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article comprises a second hollow support tube, such as a second hollow acetate tube, such as wherein the second hollow support tube is located downstream of the aerosol-forming substrate within the aerosol-generating article.

[0242] Ex 106. An aerosol generating article according to example Ex 105, wherein the second hollow support tube comprises one or more ventilation openings.

[0243] Ex 107. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article comprises a mouthpiece filter rod.

[0244] Ex 108. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article comprises a wrapper, such as a paper wrapper, such as wherein the components of the aerosol-generating article containing the aerosol-forming substrate are assembled within the wrapper.

[0245] Ex 109. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article comprises a front rod, an aerosol-forming substrate located downstream of the front rod, a first hollow support tube located downstream of the aerosol-forming substrate, a second hollow support tube located downstream of the first hollow support tube, and a mouthpiece filter rod located downstream of the second hollow tube, preferably wherein the front rod, the aerosol-forming substrate, the first hollow support tube, the second hollow support tube and the mouthpiece filter rod are surrounded by a wrapper, such as a paper wrapper.

[0246] Ex 110. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a length of between 5 millimetres and 30 millimetres.

[0247] Ex 111. An aerosol-generating article according to any preceding example, wherein the aerosol-forming substrate has a length of between 5 millimeters and 16 millimeters.

[0248] Ex 112. An aerosol-generating article according to any preceding example, wherein the wall thickness of the aerosol-forming substrate is from 5 percent to 40 percent of the outer diameter of the aerosol-forming substrate.

[0249] Ex 113. A method of forming a hollow tubular aerosol-forming substrate for an aerosol-generating article, such as an aerosol-generating article defined by any of the examples of Ex i to Ex 112, the method comprising:

[0250] forming a suspension containing heat-conducting particles, an aerosol forming agent, fibers and a binder;

[0251] casting the suspension into a hollow tubular aerosol-forming substrate and

[0252] drying the cast suspension to form a hollow tubular aerosol-forming substrate.

[0253] Ex 114. A method of forming a hollow tubular aerosol-forming substrate for an aerosol-generating article, such as an aerosol-generating article defined by any of the examples of Ex i to Ex 112, the method comprising:

[0254] forming a suspension containing heat-conducting particles, an aerosol forming agent, fibers and a binder;

[0255] extruding the suspension into a hollow tubular aerosol-forming substrate and drying the extruded suspension to form the hollow tube.

[0256] Ex 115. The method according to example Ex 114, further comprising the step of cutting the hollow tube to form a hollow tubular aerosol-forming substrate.

[0257] Ex 116. A method of forming a hollow tubular aerosol-forming substrate for an aerosol-generating article, such as an aerosol-generating article defined by any of the examples of Ex i to Ex 112, the method comprising:

[0258] forming a suspension containing heat-conducting particles, an aerosol forming agent, fibers and a binder;

[0259] casting and drying the suspension to form a sheet of aerosol-forming material, and

[0260] Giving the sheet the shape of a hollow tube.

[0261] Ex 117. The method according to example Ex 116, further comprising the step of cutting the hollow tube to form a hollow tubular aerosol-forming substrate.

[0262] Ex 118. The method according to example Ex 116 or Ex 117, wherein the step of shaping the sheet into a hollow tube includes the steps of rolling the sheet into a tubular shape and applying adhesive to an overlapped portion of the rolled sheet to maintain the tubular shape of the rolled sheet.

[0263] Ex 119. The method according to any of the examples Ex 113-118, wherein the suspension comprises water.

[0264] Ex 120. The method according to any of the examples Ex 113-Ex 119, wherein the suspension contains from 40 to 90, from 40 to 85, from 50 to 80, from 60 to 80, from 60 to 75 weight % water.

[0265] Ex 121. The method according to any one of Ex 113 to Ex 120, wherein the suspension comprises an acid, such as fumaric acid.

[0266] Ex 122. The method according to any one of Ex 113 to Ex 121, wherein the suspension comprises nicotine.

[0267] Ex 123. The method according to any one of the examples Ex 113 to Ex 122, wherein forming the suspension comprises:

[0268] forming a first mixture containing:

[0269] Aerosol forming substance;

[0270] fiber;

[0271] water;

[0272] optionally acid; and

[0273] not necessarily nicotine,

[0274] forming a second mixture containing:

[0275] heat-conducting particles; and

[0276] binder,

[0277] and adding the second mixture to the first mixture to form a combined mixture.

[0278] Ex 124. The method according to example Ex 123, wherein forming the first mixture comprises providing an aerosol forming substance or a solution containing an aerosol forming substance and nicotine.

[0279] Ex 125. The method according to example Ex 124, wherein forming the first mixture comprises adding an acid to the aerosol forming substance or a solution containing the aerosol forming substance and nicotine to form a first pre-mixture.

[0280] Ex 126. The method according to any one of Ex 123 to Ex 125, wherein forming the first mixture comprises adding water to the aerosol forming substance or a solution containing the aerosol forming substance and nicotine, or to the first premixture, to form a second premixture.

[0281] Ex 127. The method according to example Ex 126, wherein forming the first mixture comprises adding fibers to the second pre-mixture.

[0282] Ex 128. The method according to any one of the examples Ex 126-Ex 127, wherein forming the second mixture comprises mixing the heat-conducting particles and the binder.

[0283] Ex 129. The method according to any one of Ex 126 to Ex 128, wherein the method comprises first mixing the combined mixture.

[0284] Ex 130. The method according to example Ex 129, wherein the first mixing occurs at a first pressure of not more than 500, 400, 300, 250 or 200 mbar.

[0285] Ex 131. The method according to example Ex 129 or Ex 130, wherein the first stirring takes place for 1 to 10, 2 to 8, or 3 to 6 minutes, such as for about 4 minutes.

[0286] Ex 132. The method according to any one of Ex 129 to Ex 131, wherein the method comprises, after the first mixing, a second mixing.

[0287] Ex 133. The method according to example Ex 132, wherein the second mixing occurs at a second pressure that is less than the first pressure.

[0288] Ex 134. The method according to example Ex 133, wherein the second pressure is not more than 500, 400, 300, 200, 150 or 100 mbar.

[0289] Ex 135. The method according to example Ex 132, or Ex 133, or Ex 134, in which the second mixing occurs for 5 to 120, 5 to 80, 5 to 40, or 10 to 30 seconds, such as approximately 20 seconds.

[0290] Ex 136. The method according to any one of the examples Ex 116 to Ex 135, wherein casting the slurry comprises casting the slurry onto a flat support, such as a steel flat support.

[0291] Ex 137. The method according to any of the examples Ex 113-Ex 136, wherein after casting the slurry and before drying the slurry, the method comprises adjusting the thickness of the slurry, for example adjusting the thickness of the slurry to from 100 to 1000, from 200 to 900, from 300 to 800, from 500 to 700 microns, for example approximately 600 microns.

[0292] Ex 138. The method according to any one of Ex 113 to Ex 137, wherein drying the slurry comprises providing a flow of gas, such as air, over or past the slurry.

[0293] Ex 139. The method according to example Ex 138, wherein the gas stream is heated.

[0294] Ex 140. The method according to example Ex 139, wherein the gas stream is heated to a temperature of from 100 to 160 or from 120 to 140 degrees Celsius.

[0295] Ex 141. The method according to any of the examples Ex 138-Ex 140, wherein the gas flow is provided for 1 to 10 or 2 to 5 minutes.

[0296] Ex 142. The method according to any one of Ex 113 to Ex 141, wherein drying the suspension comprises drying the suspension until the moisture content of the suspension is from 1 to 20, from 2 to 15, from 2 to 10, or from 3 to 7 weight%.

[0297] Ex 143. A method according to any one of Ex 113 to Ex 142, wherein drying the suspension forms a precursor for forming an aerosol-forming substrate therefrom, the precursor being a sheet of aerosol-forming material.

[0298] Ex 14 4. An aerosol-generating system comprising an aerosol-generating article according to any of the examples of Ex i-Ex 112 and an electrical aerosol-generating device.

[0299] Ex 145. An aerosol generating system according to example Ex 144, wherein the electrical aerosol generating device is adapted to resistively heat the aerosol generating article during use.

[0300] Ex 146. An aerosol generating system according to any of the examples Ex 144 to Ex 145, wherein the electrical aerosol generating device is configured to inductively heat an aerosol generating article, such as an aerosol-forming substrate of the aerosol generating article, during use.

[0301] Examples will now be further described with reference to figures, where:

[0302] Fig. 1 shows a schematic sectional view of a first embodiment of an aerosol generating article;

[0303] Fig. 2 is a schematic cross-sectional view of a first embodiment of an aerosol generating system comprising the article of Fig. 1;

[0304] Fig. 3 shows a schematic sectional view of a second embodiment of an aerosol generating system comprising the article of Fig. 1; and

[0305] Fig. 4 shows a schematic sectional view of a third embodiment of an aerosol generating system comprising the article of Fig. 1.

[0306] Fig. 1 shows a schematic cross-sectional view of an exemplary aerosol-generating article 10 according to an embodiment of the present invention. The aerosol-generating article 10 extends from an upstream, or distal, end 18 to a downstream, or near, or mouthpiece, end 20 and has a total length of approximately 4.5 millimeters and a diameter of approximately 7.2 mm.

[0307] The aerosol-generating article 10 comprises a plurality of elements arranged coaxially and assembled within a wrapper 70. The plurality of elements forming the article are, from the distal end to the proximal end, a front rod 46, a tubular segment (part) of an aerosol-generating substrate 12 with increased thermal conductivity, a free-flow filter 34 in the form of a cardboard tube, and a mouthpiece filter 42. The wrapper 70 is cigarette paper.

[0308] The front rod 4 6, also referred to as the upstream element, is located immediately upstream of the tubular aerosol-forming substrate 12. The front rod 46 is provided in the form of a cylindrical rod made of cellulose acetate. The front rod 46 has a diameter of approximately 7.2 mm and a length of approximately 5 millimeters. The RTD of the front rod 46 is approximately 3.0 millimeters of water.

[0309] The tubular segment (portion) of the aerosol-forming substrate 12 has an outer diameter of approximately 7.2 millimeters, an inner diameter of approximately 6.8 millimeters, and a length of approximately 12 millimeters. The aerosol-forming substrate 12 is formed from a twisted sheet of aerosol-forming material containing heat-conducting particles 44. The tubular aerosol-forming substrate 12 is capable of forming an aerosol when heated to a temperature of from 150 degrees Celsius to 350 degrees Celsius. Some specific examples of suitable aerosol-forming substrate compositions are given below.

[0310] The cardboard tube 34 has a length of 16 mm and provides a free space inside the article 10 in which the volatile components generated by heating the aerosol-forming substrate can cool and form an aerosol.

[0311] The mouthpiece element 42 is provided in the form of a cylindrical rod made of low-density cellulose acetate. The mouthpiece element 42 has a length of approximately 12 millimeters and an outer diameter of approximately 7.2 mm. The RTD of the mouthpiece element 42 is approximately 12 millimeters of water.

[0312] It should be understood that the configuration of the aerosol-generating article 10 in Fig. 1 is shown only as an example. The thermally improved tubular aerosol-forming substrate 12 can be used, for example, in an aerosol-generating article having a longer length, such as 80 mm, and a thinner thickness, such as 4.5 mm in diameter.

[0313] In a particular embodiment of the aerosol generating article, as shown in Fig. 1, the tubular segment (portion) 12 of the aerosol-forming substrate contains, on a dry weight basis, approximately 76.1 wt. % of thermally conductive particles 44. In this embodiment, the thermally conductive particles 44 are graphite particles, namely FP 99.5 graphite particles (>99.5% purity) from "Graphit Kropfmiil GmbH", "AMG Graphite GK", although other particles or mixtures of particles can also be used. Each thermally conductive particle has a thermal conductivity of approximately 6 W / (m⋅K) in at least one direction at 25 degrees Celsius.

[0314] The tubular aerosol-forming substrate 12 comprises, on a dry weight basis, approximately 17.7% by weight of an aerosol-forming substance. In this embodiment, the aerosol-forming substance is glycerol, in particular food-grade glycerol "ICOF Europe" (with a purity of >99.5%).

[0315] The tubular aerosol-forming substrate 12 contains, on a dry weight basis, approximately 3.9% by weight of fibers. In this embodiment, the fibers are cellulose fibers, in particular "Birch" cellulose fibers from "Stora Enso OYJ."

[0316] The tubular aerosol-forming substrate 12 contains, on a dry weight basis, approximately 2.3 wt.% of a binder. In this embodiment, the binder is guar gum, specifically guar gum from Gumix International Inc.

[0317] The tubular aerosol-forming substrate contains approximately 10% by weight water when measured at 25 degrees Celsius.

[0318] In other embodiments, the tubular aerosol-forming substrate 12 further comprises one or more of nicotine, an acid such as fumaric acid, a plant material such as cloves or rosemary, and a flavoring agent.

[0319] The tubular aerosol-forming substrate 12 has a thermal conductivity of at least 0.1 W / (m⋅K) in at least one direction at 25 degrees Celsius. The aerosol-forming substrate 12 may have a thermal conductivity of 0.2, 0.5, 1, 1.5 or more W / (m⋅K) in at least one direction at 25 degrees Celsius.

[0320] Each of the heat-conducting particles 44 has a substantially spherical shape. The heat-conducting particles 44 are substantially uniformly distributed throughout the aerosol-forming substrate. The particle size distribution has a particle size by volume D10 of approximately 6 microns, a particle size by volume D50 of approximately 20 microns, and a particle size by volume D90 of approximately 56 microns. Each of the heat-conducting particles 44 has a particle size greater than approximately 1 micron and less than approximately 300 microns.

[0321] The heat-conducting particles 44 have a density of approximately 2200 kilograms per cubic meter. The aerosol-forming substrate has a density of approximately 800 kilograms per cubic meter.

[0322] An aerosol-forming substrate is formed by the process described below.

[0323] The suspension is formed using a laboratory disperser capable of mixing viscous liquids, dispersing powders in liquids, and removing gas from the mixture (e.g., using a vacuum or other suitable low pressure). In this embodiment, a commercially available laboratory disperser from "PC Laborsystem" was used.

[0324] To form a suspension, a first mixture is formed by adding approximately 7.11 grams of aerosol forming agent, then approximately 157.5 grams of water, and then approximately 1.57 grams of fibers to a laboratory disperser. These first ingredients are then mixed at 600-700 rpm for 5 minutes at 25 degrees Celsius to ensure a homogeneous mixture and hydrate the fibers. A second mixture is then formed by manually mixing approximately 32.95 grams of heat-conducting particles and approximately 0.92 grams of binder. This mixing of the second mixture eliminates the formation of lumps in the laboratory dispersion. The second mixture is then added to the first mixture to form a combined mixture. The combined mixture is then stirred at 5000 rpm for 4 minutes at 25 degrees Celsius and a first reduced pressure of approximately 200 mbar.Reduced pressure can help ensure that the heat-conducting particles are uniformly dispersed throughout the mixture and that the combined mixture contains little entrapped air and few lumps. The combined mixture is then stirred at 5000 rpm for an additional 20 minutes at 25 degrees Celsius and a second reduced pressure of approximately 100 mbar. This second reduced pressure can help remove any remaining air bubbles. This forms a castable slurry.

[0325] The slurry is then cast and dried using a suitable apparatus. In this embodiment, a commercially available "Mathis Labcoater" is used. This device contains stainless steel, a flat support, and a mold blade for adjusting the thickness of the slurry cast onto the flat support.

[0326] The slurry is cast onto a flat support, and the gap between the mold blade and the flat support is set at 0.6 mm. This ensures that the slurry thickness is no more than 0.6 mm at any given point.

[0327] The suspension is then dried with hot air at a temperature of 120 to 140 degrees Celsius for 2 to 5 minutes. After this drying, a sheet of aerosol-forming substrate is formed. This sheet has a thickness of approximately 300 microns, a grammage of approximately 250 grams per square meter, and a density of approximately 0.79 kilograms per cubic meter.

[0328] The sheet is then rolled to form a tube. Adhesive is applied to the overlapping portion of the rolled sheet to secure the sheet into a tube shape, and the tube is then cut into 12 mm lengths to form a tubular aerosol-forming substrate 12.

[0329] After the tubular aerosol-forming substrate 12 is formed, the aerosol-generating article 10 is assembled by arranging various components of the article 10 and wrapping the components in a wrapper 70.

[0330] Other embodiments may have the same structure as described above, but have an aerosol-forming substrate with a different composition. For example, in an additional embodiment, the aerosol-forming material comprises a tube of thermally improved homogenized tobacco containing thermally conductive particles 44. The thermally conductive particles 44 are carbon particles, especially expanded graphite particles, having a particle size distribution with a D10 particle size of 6.6 microns, a D50 particle size of 20 microns, and a D90 particle size of 56 microns. Each of the expanded graphite particles has a particle size greater than 2 microns and less than 100 microns. The expanded graphite particles have an average volume particle size of approximately 35 microns. Each of the expanded graphite particles has a substantially spherical shape. The expanded graphite particles have a density of less than 1000 kilograms per cubic meter.The aerosol-forming substrate, containing the aerosol-forming material and heat-conducting particles 44, has a combined density of approximately 760 kilograms per cubic meter. Expanded graphite particles comprise approximately 5% of the aerosol-forming substrate by weight.

[0331] The aerosol-forming substrate tube 12 is formed by a process including the following steps:

[0332] • pre-mixing the binder, guar gum, with the aerosol forming agent, glycerin, to form a first pre-mix;

[0333] • pre-mixing finely ground tobacco material and a powder consisting of 44 expanded graphite particles and having a bulk density of approximately 0.065 grams per cubic centimeter to form a second pre-mixture;

[0334] • mixing the first and second premixes with water to form a suspension;

[0335] • Homogenization of suspension using a high shear mixer;

[0336] • casting suspension onto a conveyor belt;

[0337] • adjusting the thickness of the slurry and drying the slurry to form a sheet of the aerosol-forming substrate; and

[0338] • rolling a sheet of aerosol-forming substrate into a tube and cutting the tube to form tubular segments (parts) of the aerosol-forming substrate.

[0339] Aerosol-forming substrates formed with compositions containing conductive particles according to the present invention demonstrated improved aerosol delivery compared to comparative substrates without thermally conductive particles.

[0340] Fig. 2 shows a schematic cross-sectional view of a first embodiment of an aerosol generating system 100. The system 100 comprises an aerosol generating device 102 and an aerosol generating article 10, as shown in Fig. 1.

[0341] The aerosol generating device 102 comprises a battery 104, a controller 106, a heating plate 108 connected to the battery, and a puff detection mechanism (not shown). The controller 106 is connected to the battery 104, the heating plate 108, and the puff detection mechanism.

[0342] The aerosol generating device 102 further comprises a housing 110 defining a substantially cylindrical cavity for receiving a portion of the article 10 therein. A heating plate 108 is located centrally within the cavity and extends longitudinally from the base of the cavity.

[0343] In this embodiment, heating plate 108 comprises a substrate and an electrically resistive track located on the substrate. Battery 104 is connected to heating plate 108 so as to be able to pass current through the electrically resistive track and heat the electrically resistive track and heating plate 108 to an operating temperature.

[0344] In use, the user inserts the article 10 into the cavity, causing the heating plate 108 to penetrate the upstream element 46 and pass into the internal channel or cavity of the tubular aerosol-forming substrate 12 of the article 10. Fig. 3 shows the article 10 inserted into the cavity of the device 102 and the heating plate passing into the internal channel of the tubular aerosol-forming substrate.

[0345] The user then takes a puff on the downstream end of the article 10. This causes air to flow through the air inlet (not shown) of the device 102, then through the article 10, from the upstream end 18 to the downstream end 20 and into the user's mouth.

[0346] When the user takes a puff on product 10, air flows through the device's air inlet. The puff detection mechanism detects that the air flow rate through the air inlet has increased to a value exceeding a non-zero threshold flow rate. The puff detection mechanism accordingly sends a signal to controller 106. Controller 106 then controls battery 104 to pass current through the electrically resistive track and heat heating plate 108. This heats the tubular aerosol-forming substrate.

[0347] Thermal conductive particles 44 have significantly higher thermal conductivity than the surrounding aerosol-forming material. As such, these particles can act as localized hot spots and provide a more uniform temperature throughout the aerosol-forming substrate, particularly in the radial direction from the heating plate 108, where a significant temperature gradient would exist with prior art substrates. Furthermore, since the aerosol-forming substrate is tubular, the temperature between the inner and outer surfaces of the tube equalizes relatively quickly.The combination of a tubular design for the aerosol-forming substrate and the presence of heat-conducting particles in the aerosol-forming substrate allows a large proportion of the aerosol-forming substrate to quickly reach a sufficiently high temperature for the release of volatile compounds and thus provides higher efficiency in the use of the aerosol-forming substrate.

[0348] Heating the aerosol-forming substrate causes the aerosol-forming substrate to release volatile compounds. These compounds are entrained in air flowing from the upstream end 18 of the article 10 to the downstream end 20 of the article 10. The compounds cool and condense to form an aerosol as they pass through the cardboard tube 34. The aerosol then passes through the mouthpiece element 42, which can filter out unwanted particles entrained in the airflow, and into the user's mouth.

[0349] When the user stops inhaling into the device 10, the airflow rate through the device's air inlet decreases to a value below the non-zero threshold flow rate. This is detected by the puff detection mechanism. The puff detection mechanism accordingly sends a signal to the controller 106. The controller 106 then controls the battery 104 to reduce the current passed through the electrically resistive circuit to zero.

[0350] After a number of puffs on product 10, the user may decide to replace product 10 with a fresh product.

[0351] Fig. 3 shows a schematic cross-sectional view of a second embodiment of an aerosol generating system 300. The system 300 comprises an aerosol generating device 302 and an aerosol generating article 10, as shown in Fig. 1.

[0352] Aerosol generating device 302 comprises a battery 304, a controller 306, an external resistive heater 308, and a puff detection mechanism (not shown). Controller 306 is connected to battery 304, resistive heater 308, and puff detection mechanism.

[0353] The aerosol generating device 302 further comprises a casing 310 that forms a substantially cylindrical cavity for accommodating a portion of the article 10 therein. An external heater 208 is located on the inner surface of the cavity.

[0354] The use of the system is similar to that described above with respect to the system of Fig. 2, with the difference that the tubular substrate 12 forming the aerosol is heated from the outside, rather than by a heater located in the interior of the aerosol forming substrate.

[0355] Fig. 4 shows a schematic cross-sectional view of a third embodiment of an aerosol generating system 400. The system 400 comprises an aerosol generating device 402 and an aerosol generating article 10, as shown in Fig. 1.

[0356] The aerosol generating device 402 comprises a battery 404, a controller 406, an induction coil 408, and a puff detection mechanism (not shown). The controller 4 06 is connected to the battery 404, the induction coil 408, and the puff detection mechanism.

[0357] The aerosol generating device 402 further comprises a housing 410 that forms a substantially cylindrical cavity for accommodating a portion of the article 10 therein. An induction coil 408 extends spirally around the cavity.

[0358] The battery 404 is connected to the induction coil 408 so as to be able to pass an alternating current through the induction coil 408.

[0359] In use, the user inserts the article 10 into the cavity. Fig. 4 shows the article 10 inserted into the cavity of the device 402. An air flow is detected and the device is activated as described above with respect to the system of Fig. 1. When a puff is detected, the controller 406 controls the battery 404 so as to pass an alternating current through the induction coil 408. This causes the induction coil 408 to generate a fluctuating electromagnetic field. The aerosol-forming substrate 12 is located within this fluctuating electromagnetic field. The materials of the particles 44, such as graphite and expanded graphite, are current-receiving materials. Thus, the fluctuating electromagnetic field generates eddy currents in the particles 44. This causes the particles 44 to heat up, thereby also heating the aerosol-forming material of the aerosol-forming substrate.

[0360] For the purposes of the present description and the appended claims, except where otherwise indicated, all numbers expressing quantities, amounts, percentages, etc., shall be understood as modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points and include any intermediate ranges therebetween, which may or may not be specifically listed herein. Therefore, in this context, the number A is understood as A±10% of A. In this context, the number A may be considered to include numerical values ​​that are within the common standard error for the measurement of the property that the number A modifies. The number A, in some cases, when used in the appended claims, may deviate by the percentages listed above, provided that the amount by which A deviates does not materially affect the essential and novel characteristic(s) of the claimed invention.All ranges also include the disclosed maximum and minimum points and include any intermediate ranges therebetween that may or may not be specifically listed herein.

Claims

1. An aerosol generating article for producing an inhalable aerosol upon heating, wherein: the article comprises a plurality of components including an aerosol-forming substrate, wherein the aerosol-forming substrate has the form of a hollow tubular portion that forms a substrate cavity extending between an upstream end of the aerosol-forming substrate and a downstream end of the aerosol-forming substrate, wherein the aerosol-forming substrate comprises a plurality of heat-conducting particles and an aerosol-forming substance, each of the plurality of thermally conductive particles has a thermal conductivity greater than 0.3 W / (m⋅K) in at least one direction at 25 °C and The said substrate is made in the form of a tube having an outer diameter and an inner diameter, wherein the inner diameter is from 2.5 to 19 mm.

2. The article of claim 1, wherein the aerosol-forming substrate contains, on a dry weight basis, from 5 to 95% by weight, such as from 10 to 90% by weight, of thermally conductive particles, wherein each thermally conductive particle of the thermally conductive particles has a thermal conductivity of at least 1 W / (m⋅K) in at least one direction at 25 °C.

3. An article according to any one of claims 1 and 2, wherein the aerosol-forming substrate has a thermal conductivity of at least 0.12 W / (m⋅K) in at least one direction at 25 °C.

4. An article according to any one of the preceding claims, wherein each of the thermally conductive particles consists of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond.

5. An article according to any one of the preceding claims, wherein the aerosol-forming substrate comprises, on a dry weight basis: from 10 to 85% by weight of thermally conductive particles; from 7 to 60% by weight of an aerosol former; from 2 to 20% by weight of fibers; and from 2 to 10% by weight of a binder, wherein each of the thermally conductive particles consists of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond.

6. An article according to any of the preceding claims, wherein the heat-conducting particles are uniformly distributed throughout the aerosol-forming substrate.

7. An article according to any of the preceding claims, wherein the aerosol-forming substrate comprises one or more organic materials, such as tobacco.

8. The article according to any one of claims 1-6, wherein the aerosol-forming substrate is a tobacco-free aerosol-forming substrate.

9. An article according to any of the preceding claims, wherein the length of the tube is from 5 to 100 mm and the outside diameter is from 3 to 20 mm.

10. The product according to item 9, wherein the length of the tube is from 8 to 25 mm, the outer diameter of the tube is from 6 to 8 mm, and the inner diameter of the tube is from 5 to 7.9 mm.

11. An article according to any of the preceding claims, wherein the hollow tubular portion is a rolled sheet of aerosol-forming material, such as a rolled sheet of homogenized tobacco material or a rolled sheet of tobacco-free aerosol-forming material.

12. The article according to any one of claims 1 to 10, wherein the hollow tubular portion is an extruded tube of aerosol-forming material, such as an extruded tube of homogenized tobacco material or, for example, an extruded tube of tobacco-free aerosol-forming material.

13. A method of forming a hollow tubular aerosol-forming substrate for an aerosol-generating article according to any one of claims 1-12, the method comprising: forming a suspension containing heat-conducting particles, an aerosol forming agent, fibers, and a binder, wherein each of the heat-conducting particles has a thermal conductivity greater than 0.3 W / (m⋅K) in at least one direction at 25 °C; casting and drying the slurry to form a sheet of aerosol-forming material; and giving the sheet the shape of a hollow tube, said hollow tube having an outer diameter and an inner diameter, the inner diameter being from 2.5 to 19 mm.

14. The method according to claim 13, wherein forming the suspension comprises: formation of a first mixture containing: aerosol forming agent; fibers; water; optionally acid; and not necessarily nicotine, formation of a second mixture containing: heat-conducting particles; and binder, and adding the second mixture to the first mixture to form a combined mixture.

15. An aerosol generating system comprising an aerosol generating article according to any one of claims 1-12 and an electrical aerosol generating device, wherein preferably the electrical aerosol generating device is configured to resistively heat the article during use or the electrical aerosol generating device is configured to inductively heat the article, for example an aerosol-forming substrate of the article during use.

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