Thermally enhanced aerosol-forming substrate

Abstract

An aerosol-forming substrate for use in a heated aerosol-generating article is provided, the aerosol-forming substrate comprising a co-laminate sheet including a layer of an aerosol-forming material and a layer of a carbon-based thermally conductive material.

Description

[Technical field]

[0001] The present disclosure relates to an aerosol-forming substrate. The present disclosure also relates to a rod, an aerosol-generating article, and an aerosol-generating system comprising the aerosol-forming substrate, as well as methods of making the aerosol-forming substrate, the rod, and the aerosol-generating article. [Background technology]

[0002] A typical aerosol generating system comprises an aerosol generating device and an aerosol-generating article that includes an aerosol-forming substrate. In use, the aerosol generating device interacts with the aerosol-generating article to heat the aerosol-forming substrate, causing the aerosol-forming substrate to release volatile compounds. These compounds cool and form an aerosol, which is inhaled by the user.

[0003] Known aerosol-forming substrates typically have a relatively low thermal conductivity. This may be undesirable, especially in aerosol generating systems where a blade is inserted into the aerosol-forming substrate and heated to heat the aerosol-forming substrate. This is because the low thermal conductivity of the aerosol-forming substrate may result in a relatively large temperature gradient of the aerosol-forming substrate during use. This may mean that the part of the aerosol-forming substrate located furthest from the blade does not reach high temperatures and therefore does not release as many volatile compounds as if the aerosol-forming substrate had a higher thermal conductivity. In other words, the low thermal conductivity of the aerosol-forming substrate may undesirably result in a reduced efficiency of use of the aerosol-forming substrate.

[0004] Furthermore, known aerosol-forming substrates are typically not inductively heatable to an operating temperature. This means that a separate susceptor element is typically required for inductive heating. This can increase costs. Furthermore, this can lead to the same problems as mentioned above. For example, if an inductively heated susceptor element is placed in a central position of the substrate, the part of the aerosol-forming substrate located at the farthest position from the susceptor element may not reach high temperatures and therefore may not release many volatile compounds.

[0005] Attempts have been made to increase the thermal conductivity of aerosol-forming substrates, but to date these attempts have fallen short in one or more respects.

[0006] It is an object of the present invention to provide an improved aerosol-forming substrate, for example an aerosol-forming substrate having increased thermal conductivity. It is also an object of the present invention to provide such an aerosol-forming substrate, which has increased thermal conductivity while also having improved tensile strength. Summary of the Invention

[0007] According to the present disclosure, an aerosol-forming substrate is provided. The aerosol-forming substrate may be suitable for use in a heated aerosol-generating article. The aerosol-forming substrate may include a co-laminate sheet. The co-laminate sheet may include a layer of an aerosol-forming material. The co-laminate sheet may include a layer of a carbon-based thermally conductive material.

[0008] Thus, according to a first aspect of the present disclosure, there is provided an aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising a co-laminate sheet comprising a layer of an aerosol-forming material and a layer of a carbon-based thermally conductive material.

[0009] As used herein, the term "carbon-based thermally conductive material" is used to refer to a material that includes carbon, such as a material that includes or consists of one or more of graphite, expanded graphite, graphene, carbon nanotubes, and charcoal.

[0010] A layer of carbon-based thermally conductive material comprising or consisting of at least one of graphite and expanded graphite may be particularly preferred. The layer of carbon-based thermally conductive material may be referred to as a carbon material or a carbon-containing material.

[0011] Advantageously, the layer of carbon-based thermally conductive material may increase the thermal conductivity of the aerosol-forming substrate. This may provide a more uniform temperature distribution throughout the substrate during use. This may allow a large portion of the aerosol-forming substrate to reach a temperature high enough to release volatile compounds, thus allowing for more efficient use of the aerosol-forming substrate. Alternatively, or in addition, an increase in the thermal conductivity of the substrate may allow a heater, such as a heating blade configured to heat the substrate, to operate at a lower temperature and therefore require less power.

[0012] Advantageously, layers of carbon-based thermally conductive materials such as those listed above, particularly those containing graphite and expanded graphite, may have high thermal conductivity and low density, and thus may substantially improve the thermal conductivity of the aerosol-forming substrate without significantly increasing the density of the aerosol-forming substrate. It may be advantageous to avoid significantly increasing the density of the aerosol-forming substrate, as this may increase the weight for a given volume of substrate, and therefore the transportation costs.

[0013] The term "sheet" as used herein refers to a layered element having a width and length substantially greater than its thickness. The width of a sheet is greater than 10 mm, and preferably greater than 20, 30, 40, 50, 60, 70, 80, 90, 100 millimeters. The width of a sheet may be less than 300, 250, 200, 150 millimeters. As described, the co-laminate sheet may be subjected to processing steps such as assembly. In such cases, the "width" of the sheet may refer to the width of the sheet before assembly.

[0014] The term "co-laminate sheet" as used herein means a single sheet formed from two or more layers of material in close contact with each other. In particular, the co-laminate sheet may include a layer of aerosol-forming material in close contact with a layer of thermally conductive material. The close contact between the layer of aerosol-forming material and the layer of carbon-based thermally conductive material means that heat can be transferred by the layer of aerosol-forming material through the layer of aerosol-forming material by conduction. This improves the thermal conductivity of the aerosol-forming substrate.

[0015] The layer of carbon-based thermally conductive material may have a length and width similar to or the same as the length and width of the layer of aerosol-forming material.

[0016] The layer of carbon-based thermally conductive material may be in contact with the layer of aerosol-forming material over substantially the entire surface of the thermally conductive material.

[0017] The layers of the co-laminate sheet may form a single sheet.

[0018] The co-laminate sheet may include multiple layers of aerosol-forming material. The co-laminate sheet may include multiple layers of thermally conductive material. The or each layer of aerosol-forming material may be sandwiched between layers of thermally conductive material. Alternatively or additionally, the or each layer of thermally conductive material may be sandwiched between layers of aerosol-forming material.

[0019] The co-laminate sheet may include one or more additional layers that include materials other than the carbon-based thermally conductive material and the aerosol-forming material.

[0020] The or each layer of thermally conductive material may be in the form of a film or foil. Because the film or foil is thin, only a small volume of the aerosol-forming substrate can be taken up by the layer of thermally conductive material. However, the thermally conductive layer may be provided as a layer, which may advantageously extend throughout the entire aerosol-forming substrate, so that the thermal conductivity of the substrate is improved throughout the substrate.

[0021] The or each layer of thermally conductive material may be flexible. The or each layer of aerosol-forming material may be flexible. In this way, the co-laminate sheets may also be flexible. This may be particularly advantageous when the co-laminate sheets are assembled to form a rod of aerosol-forming substrate, as described below. The assembly of the co-laminate sheets preferably extends substantially along the entire length of the rod and across substantially the entire transverse cross-sectional area of ​​the rod.

[0022] The or each layer of thermally conductive material may have a thickness of less than 10, 5, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, or 0.02 millimeters.

[0023] The or each layer of thermally conductive material may have a thickness of 10 to 0.02, or 5 to 0.02, 3 to 0.02, 2 to 0.02, 1 to 0.02, 0.9 to 0.02, 0.8 to 0.02, 0.7 to 0.02, 0.6 to 0.02, 0.5 to 0.02, 0.4 to 0.02, 0.3 to 0.02, 0.2 to 0.02, 0.1 to 0.02, 0.09 to 0.02, 0.08 to 0.02, 0.07 to 0.02, 0.06 to 0.02, 0.05 to 0.02, 0.04 to 0.02 millimeters.

[0024] Preferably, the layer of carbon-based thermally conductive material may comprise or consist of carbon fibre, graphite or graphene.

[0025] Even more preferably, the layer of carbon-based thermally conductive material may comprise or consist of expanded graphite.

[0026] Optionally, the layer of carbon-based thermally conductive material may include both graphite and expanded graphite.

[0027] The layer of carbon-based thermally conductive material may consist of flexible graphite or flexible graphite and expanded graphite foil or film.

[0028] The layer of carbon-based thermally conductive material may have a density less than or equal to the density of the aerosol-forming material.

[0029] The layer of thermally conductive material may have a density that is at least 1, 2, 5, 10, 15, 20, 25, or 30% less than the density of the aerosol-forming material.

[0030] The aerosol-forming substrate may have a density of less than 1050, 1000, 950, 900, 850, 800, 850, 800, 750, 700, or 650 kg / m3.

[0031] The aerosol-forming substrate is 500 to 900 kg / m 3 , e.g. 600~800kg / m 3 The density may be

[0032] The layers of carbon-based thermally conductive material were prepared with densities of 3, 2, 1.8, 1.5, 1.2, 1, 0.8, 0.5, 0.2, 0.1, 0.05, and 0.02 grams per centimeter cubed (g / cm 3 )

[0033] The layer of carbon-based thermally conductive material may be of 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, or 1.8 grams per centimeter cubed (g / cm 3 ) may have a density greater than

[0034] The carbon-based thermally conductive material layer is 0.01-3, 0.01-2, 0.01-1.8, 0.01-1.5, 0.01-1.2, 0.01-1, 0.01-0.8, 0.01-0.5, 0.02-3, 0.02-2, 0.02-1.8, 0.02-1.5, 0.02-1.2, 0.02-1, 0.02-0.8, 0.02-0.5, 0.01-3, 0.05-2, 0.05-1.8, 0.05-1.5, 0.05-1.2, 0.05-1, 0.05-0.8, 0.05-0.5g / cm3, 0.1-3, 0.1-2 , 0.1 to 1.8, 0.1 to 1.5, 0.1 to 1.2, 0.1 to 1, 0.1 to 0.8, 0.1 to 0.5, 0.2 to 3, 0.2 to 2, 0.2 to 1.8, 0.2 to 1.5, 0.2 to 1.2, 0.2 to 1, 0.2 to 0.8, 0.2 to 0.5, 0.5 to 3, 0.5 to 2, 0.5 to 1.8, 0.5 to 1.5, 0.5 to 1.2, 0.5 to 1, 0.5 to 0.8, 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 grams per centimeter cubed (g / cm3).

[0035] Advantageously, the use of a low density layer of thermally conductive material may result in a low density substrate, which may reduce the weight of a given volume of substrate and therefore reduce shipping costs.

[0036] The layer of carbon-based thermally conductive material may have a tensile strength of greater than 1, 2, 3, 4, 5, 6, 7, 8 or 9 Megapascals (MPa).

[0037] Providing an aerosol-forming substrate in the form of a co-laminate sheet comprising such a layer of carbon-based thermally conductive material may advantageously increase the tensile strength of the entire substrate. Furthermore, the layer of carbon-based thermally conductive material may provide support for the layer aerosol-forming material. Therefore, it may not be necessary for the rod of the aerosol-generating substrate to have an additional support layer. In some embodiments, during the manufacture of the aerosol-forming substrate, the aerosol-forming material may advantageously be cast directly onto the layer of carbon-based thermally conductive material.

[0038] The layer of carbon-based thermally conductive material may consist of a foil or film comprising at least 90%, 95%, 97%, 99%, 99.5%, 99.9% by weight graphite or expanded graphite.

[0039] The layer of carbon-based thermally conductive material may comprise or consist of a reconstituted carbon-based material, preferably a reconstituted sheet of graphite or expanded graphite, and even more preferably a reconstituted graphite or expanded graphite film or foil.

[0040] The reconstituted carbon-based material may include thermally conductive particles. Each of the thermally conductive particles may have a thermal conductivity of at least 1 Watt per meter Kelvin [W / (mK)] at least in one direction at 25 degrees Celsius. Some or all of the thermally conductive particles include carbon, for example at least 10, 30, 50, 70, 90, 95, 98, or 99% by weight carbon. Optionally, some or all of the thermally conductive particles include one or more of graphite, expanded graphite, graphene, carbon nanotubes, and charcoal. 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. Such materials may advantageously have a relatively high thermal conductivity.

[0041] The reconstituted carbon-based material may comprise at least 10%, 20%, 30%, 40%, 50%, 60%, 70% by weight of thermally conductive particles. The reconstituted carbon-based material may comprise less than 90%, 95%, 80% by weight of thermally conductive particles.

[0042] The reconstituted carbon-based material may comprise an aerosol former. The reconstituted carbon-based material may comprise an aerosol former in an amount of from 7 to 60% by weight on a dry weight basis.

[0043] The reconstituted carbon-based material may include fibers. The layer of reconstituted carbon-based material may include fibers, where the fibers are between 2 and 20% by weight, on a dry weight basis. Optionally, the fibers are cellulose fibers. Advantageously, cellulose fibers are inexpensive and can increase the tensile strength of the substrate.

[0044] Optionally, each of the fibers has three mutually orthogonal dimensions, and the largest dimension in the third dimension is at least 1.5, 2, 3, 5, 10, or 20 times greater than the smallest dimension in the third dimension. Optionally, each of the fibers has three mutually orthogonal dimensions, and the largest dimension in the third dimension is at least 1.5, 2, 3, 5, 10, or 20 times greater than the second largest dimension in the third dimension.

[0045] The reconstituted carbon-based material may include a binder. The reconstituted carbon-based material may include 2-10 wt. % binder on a dry weight basis. Optionally, the substrate includes at least 4, 6, or 8 wt. % binder on a dry weight basis. Optionally, the substrate includes no more than 8, 6, or 4 wt. % binder on a dry weight basis. Optionally, the substrate includes 4-10, 6-10, 8-10, 2-8, 4-8, 6-8, 2-6, 4-6, 2-4 wt. % binder on a dry weight basis. It may be particularly preferred that the substrate includes 2.1-10 wt. % binder on a dry weight basis.

[0046] Preferred binders are well known in the art and include, but are not limited to, natural pectins (such as fruit pectins, citrus pectins, or tobacco pectins), guar gums (such as hydroxyethyl guar and hydroxypropyl guar), locust bean gums (such as hydroxyethyl and hydroxypropyl locust bean gums), alginates, starches (such as modified or derivatized starches), celluloses (such as methylcellulose, ethylcellulose, ethylhydroxymethylcellulose, and carboxymethylcellulose), tamarind gum, dextran, pralon, konjac flour, xanthan gum, and the like. It may be particularly preferred that the binder is or comprises guar. It may be particularly preferred that the binder comprises or consists of one or more of carboxymethylcellulose or hydroxypropylcellulose, or a gum such as guar gum.

[0047] Optionally, the thermally conductive particles are substantially uniformly distributed throughout the layer of thermally conductive material. Optionally, the aerosol former is substantially uniformly distributed throughout the layer of thermally conductive material. Optionally, the fibers are substantially uniformly distributed throughout the layer of thermally conductive material. Optionally, the binder is substantially uniformly distributed throughout the layer of thermally conductive material. Advantageously, a uniform distribution of the components of the substrate results in the substrate having more spatially uniform properties. For example, substantially uniformly distributed thermally conductive particles will result in the substrate having a substantially uniform thermal conductivity. As another example, a substantially uniformly distributed binder or fiber may result in a substrate having a substantially uniform tensile strength.

[0048] Advantageously, one or both of the fibers and binder may increase the tensile strength of the reconstituted carbon-based material. The increased tensile strength may allow for the production of sheets of the reconstituted carbon-based material that do not tear easily. The increased tensile strength may allow for the production of the reconstituted carbon-based material using existing manufacturing machinery.

[0049] Each thermally conductive particle may have a “particle size.” The meaning of the term “particle size” and methods for measuring particle size are described below.

[0050] The thermally conductive particles may be characterized by a particle size distribution. The particle size distribution may have particle sizes of the numbers D10, D50, and D90. The particle size of the number D10 is defined such that 10% of the particles have a particle size equal to or less than the particle size of the number D10. Similarly, the particle size of the number D50 is defined such that 50% of the particles have a particle size equal to or less than the particle size of the number D50. Thus, the particle size of the number D50 may be referred to as the median particle size. The particle size of the number D90 is defined such that 90% of the particles have a particle size equal to or less than the particle size of the number D90. Thus, if there are 1,000 particles in a distribution and the particles are arranged in ascending order of particle size, the particle size of the number D10 is expected to be approximately equal to the particle size of the 100th particle, the particle size of the number D50 is expected to be approximately equal to the particle size of the 500th particle, and the particle size of the number D90 is expected to be approximately equal to the particle size of the 900th particle.

[0051] The particle size distribution may have particle sizes of volume D10, D50, and D90. The particle size of volume D10 is defined such that 10% of the total volume of all particles is occupied by the total volume of particles having a particle size equal to or smaller than the particle size of volume D10. Similarly, the particle size of volume D50 is defined such that 50% of the total volume of all particles is occupied by the total volume of particles having a particle size equal to or smaller than the particle size of volume D50. Also, the particle size of volume D90 is defined such that 90% of the total volume of all particles is occupied by the total volume of particles having a particle size equal to or smaller than the particle size of volume D90.

[0052] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D10, the particle size number D10 being at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0053] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D10, the particle size number D10 being less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0054] A compromise must be made when determining particle size: larger thermally conductive particles may advantageously increase the thermal conductivity of the reconstituted carbon-based material, and thus the aerosol-forming substrate containing the reconstituted carbon-based material, more than smaller thermally conductive particles. However, larger thermally conductive particles may reduce the space available for the aerosol-forming material within the substrate.

[0055] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D50, the particle size number D50 being at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0056] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D50, the particle size number D50 being less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0057] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D90, the particle size number D90 being at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0058] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D90, the particle size number D90 being less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0059] Optionally, the thermally conductive particles have a particle size distribution having a particle size number D10 and a particle size number D90, where the particle size number D90 is 50, 40, 30, 20, 10, or 5 times smaller than the particle size number D10.

[0060] Optionally, the thermally conductive particles have a particle size distribution having a particle size number D10 and a particle size number D90, where the particle size number D90 is at least 1.5 times, 2 times, 3 times, 5 times, 10 times, or 20 times the particle size number D10.

[0061] A compromise must be made regarding particle size distribution. For example, a tighter particle size distribution, characterized by a smaller ratio of particle sizes D90 to D10, may advantageously provide a more uniform thermal conductivity throughout the reconstituted carbon-based material. This is because there is less variation in particle size at different locations within the substrate. This may advantageously allow for more efficient use of the aerosol-forming material throughout the aerosol-forming substrate. However, a tighter particle size distribution may disadvantageously be more difficult and expensive to achieve. The inventors have found that the particle size distribution described above may provide an optimal compromise between these two factors.

[0062] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D10, and the particle size in volume D10 is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0063] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D10 that is less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0064] Optionally, the thermally conductive particles have a particle size distribution with a particle size, volume D50, where the particle size, volume D50, is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0065] Optionally, the thermally conductive particles have a particle size distribution with a particle size, volume D50, of less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0066] Optionally, the thermally conductive particles have a particle size distribution with a particle size, volume D90, of at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0067] Optionally, the thermally conductive particles have a particle size distribution with a particle size, volume D90, of less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0068] It may be particularly preferred that the thermally conductive particles have a particle size distribution with a particle size volume D10 of 1 to 20 microns. Alternatively or additionally, it may be particularly preferred that the thermally conductive particles have a particle size distribution with a particle size volume D90 of 50 to 300 microns, or 50 to 200 microns.

[0069] Optionally, the thermally conductive particles have a particle size distribution having a volume D10 particle size and a volume D90 particle size, the volume D90 particle size being no greater than 50, 40, 30, 20, 10, or 5 times the volume D10 particle size.

[0070] Optionally, the thermally conductive particles have a particle size distribution having a particle size in volume D10 and a particle size in volume D90, where the particle size in volume D90 is at least 1.5 times, 2 times, 3 times, 5 times, 10 times, or 20 times the particle size in volume D10.

[0071] As noted above, compromises have to be made with respect to particle size distribution, and the inventors have found that the particle size distribution described above may provide an optimal compromise.

[0072] Optionally, each of the thermally conductive particles has a particle size of at least 0.01, 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 1,000, 500, 300, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns or less. It may be particularly preferred that each of the thermally conductive particles has a particle size of at least 1 micron. Alternatively or additionally, it may be particularly preferred that each of the thermally conductive particles has a particle size of 300 microns or less. Particles smaller than 1 micron may be difficult to handle during manufacturing. Particles larger than 300 microns may occupy a significant amount of space within a substrate that may be used for the aerosol-forming material. Thus, it may be particularly advantageous for each of the thermally conductive particles to have a particle size of at least 1 micron, or a particle size of no more than 300 microns, or both.

[0073] Optionally, each of the thermally conductive particles has three mutually orthogonal dimensions, and the largest dimension of the three dimensions is 10 times, 8 times, 5 times, 3 times, or 2 times or less than the smallest dimension of the three dimensions. Optionally, each of the thermally conductive particles has three mutually orthogonal dimensions, and the largest dimension of a third dimension is 10 times, 8 times, 5 times, 3 times, or 2 times or less than the largest dimension of a second of the three dimensions. Optionally, each of the thermally conductive particles is substantially spherical. Advantageously, the orientation of 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 may result in less variability between different substrates where the orientation of the particles is not controlled. Additionally, substantially spherical particles may be easier to characterize.

[0074] Optionally, the thermally conductive particles comprise at least 10, 20, 50, 100, 200, 500, or 1000 particles. Advantageously, a larger number of particles in the aerosol-forming substrate may allow the thermal conductivity of the substrate to be more uniform.

[0075] Optionally, the substrate comprises at least 20, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% by weight of thermally conductive particles on a dry weight basis. Optionally, the substrate comprises 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 on a dry weight basis. Optionally, the substrate comprises 10-90, 20-90, 30-90, 40-90, 50-90, 60-90, 70-90, 80-90, 10-80, 20-80, 30-80, 40-80, 50-80, 60-80, 70-80, 10-70, 20-70, 30-70, 40-70, 50-70, 60-70, 10-60, 20-60, 30-60, 40-60, 50-60, 10-50, 20-50, 30-50, 40-50, 10-40, 20-40, 30-40, 10-30, 20-30, or 10-20 weight percent thermally conductive particles on a dry weight basis. It may be particularly preferred that the substrate comprises, on a dry weight basis, 50 to 90 wt %, more preferably 60 to 90 wt %, or even more preferably 65 to 85 wt % thermally conductive particles.

[0076] Provision must be made for the weight percentage of thermally conductive particles in the substrate. Increasing the weight percentage of particles in the aerosol-forming substrate may advantageously increase the thermal conductivity of the substrate. However, increasing the weight percentage of particles in the aerosol-forming substrate may also reduce the available space for one or more of the aerosol formers, binders, and fibers, which may result in a substrate that forms less aerosol or has less tensile strength.

[0077] The layer of carbon-based thermally conductive material is tobacco-free. The layer of carbon-based thermally conductive material may be nicotine-free.

[0078] The layer of carbon-based thermally conductive material may be formed by a casting process.

[0079] The co-laminate sheet may include or have the form of an assembly of sheets. The carbon-based thermally conductive material may have sufficient tensile strength to withstand the assembly process while supporting the aerosol-forming material layer.

[0080] The layer of carbon-based thermally conductive material may have a thermal conductivity of greater than 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, or 1500 W / (mK). The thermal conductivity may be the thermal conductivity measured at 25°C.

[0081] The layer of carbon-based thermally conductive material may exhibit anisotropic thermal conductivity. The layer of carbon-based thermally conductive material may be disposed in a plane or may define a plane. The thermal conductivity of the layer of carbon-based thermally conductive material in the plane may be greater than 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, or 1500 W / mK. The thermal conductivity may be measured at 25°C.

[0082] Advantageously, increasing the thermal conductivity of the layer of thermally conductive material may increase the thermal conductivity of the aerosol-forming substrate.

[0083] Expanded graphite is available in densities of 2, 1.8, 1.5, 1.2, 1, 0.8, or 0.5, 0.2, 0.1, 0.05, and 0.02 grams per centimeter cubed (g / cm 3 )

[0084] Expandable graphite is available in densities of 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, or 1.8 grams per centimeter cubed (g / cm 3 ) may have a density greater than

[0085] Expanded graphite is 0.01~3, 0.01~2, 0.01~1.8, 0.01~1.5, 0.01~1.2, 0.01~1, 0.01~0.8, 0.01~0.5, 0.02~3, 0.02~2, 0.02~1.8, 0.02~1.5, 0.02~1.2, 0.02~1, 0.02~0.8, 0.02~0.5, 0.01~3, 0.05~2, 0.05~1.8, 0.05~1.5, 0.05~1.2, 0.05~1, 0.05~0.8, 0.05~0.5g / cm 3 , 0.1~3, 0.1~2, 0.1~1.8, 0.1~1.5, 0.1~1.2, 0.1~1, 0.1~0.8, 0.1~1.5, 0.2~3, 0.2~2, 0.2~1.8, 0.2~1.5, 0.2~1.2, 0.2~1, 0.2~0.8, 0.2~0.5, 0.5~3, 0.5~2, 0.5~1.8, 0.5~1.5, 0.5~1.2, 0.5~1, 0.5~0.8, 0.8~3, 0.8~2, 0.8~1.8, 0.8~1.5, 0.8~1.2, 0.8~1 Grams per centimeter cubed (g / cm 3 )

[0086] The layer of carbon-based thermally conductive material may comprise greater than 10, 30, 50, 70, 80, 90, 95, 98, 99, 99.5, or 99.9% by weight carbon. The layer of carbon-based thermally conductive material may consist of carbon except for trace impurities.

[0087] The layer of carbon-based thermally conductive material may comprise 90, 80, 70, 60, 50, 20, 10, or 5 percent by weight or less of the aerosol-forming substrate. The layer of carbon-based thermally conductive material may comprise 0.1, 0.2, 0.5, 1, 2, 3, 5, 10, 20, 30, 40, or 50 percent by weight or more of the aerosol-forming substrate. The layer of carbon-based thermally conductive material may comprise 20-90, 20-90, 30-90, 40-90, 20-80, 30-80, 40-80, 20-70, 30-70, 40-70, 20-60, 30-60, 40-60, 20-50, or 30-50 percent by weight of the aerosol-forming substrate.

[0088] Advantageously, the inventors have found that such weight percentages provide an optimal compromise between increasing the thermal conductivity of the aerosol-forming substrate and maintaining sufficient aerosol-forming material to form an adequate amount of aerosol.

[0089] The layer of aerosol-forming material may have a thermal conductivity of 0.1 W / mK to 0.2 W / mK. This may be the case when the aerosol-forming material is a standard homogenized cigarette. Thus, in some embodiments, the aerosol-forming material may have a thermal conductivity of less than 0.2 W / mK, for example, when measured at 25° C., and the layer of carbon-based thermally conductive material may have a thermal conductivity of greater than 0.22 W / mK, preferably much greater than 0.22 W / mK, for example, when measured at 25° C. The layer of carbon-based thermally conductive material may have a thermal conductivity as high as 1700 W / mK, for example, as found in commercially available graphite foils along its planar direction.

[0090] These thermal conductivities may be measured when the moisture content of the material is 0-20, or 5-15, for example about 10%. The thermal conductivities may be measured when the material contains 0-20, or 5-15, for example about 10% water by weight. The moisture or moisture content of the material may be measured using a titration method. The moisture or moisture content of the material may be measured using the Karl Fischer method.

[0091] The aerosol-forming material is preferably configured to generate an aerosol upon heating, for example, upon heating to a temperature between 120 degrees Celsius and 395 degrees Celsius. In some embodiments, the layer of carbon-based thermally conductive material is not configured to generate an aerosol upon heating, for example, upon heating to a temperature between 120 degrees Celsius and 350 degrees Celsius. Thus, in these embodiments, the layer of carbon-based thermally conductive material is not an aerosol-forming material. The role of the carbon-based thermally conductive material in such embodiments is to facilitate the transfer of heat to allow for optimized aerosol generation from the aerosol-forming material.

[0092] The aerosol-forming material may include one or more organic materials, such as tobacco. The aerosol-forming material may include one or more of herb leaves, tobacco leaves, tobacco stem fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco. Preferably, the aerosol-forming material may be formed from homogenized tobacco. Preferably, the aerosol-forming material includes tobacco and an aerosol former. Preferably, the aerosol-forming material is configured to generate an aerosol when heated to a temperature between 120 degrees Celsius and 395 degrees Celsius. The aerosol-forming material may be a homogenized tobacco material including an aerosol former, such as glycerin or propylene glycol. The first material may further include fibers and a binder to improve the structure of the first material.

[0093] Advantageously, one or both of the fibers and the binder may increase the tensile strength of the aerosol-forming material. The increased tensile strength may allow for the production of co-laminate sheets of aerosol-forming substrates that do not tear easily. The increased tensile strength may allow for the production of co-laminate sheets of aerosol-forming substrates using existing manufacturing machinery.

[0094] The aerosol-forming material may include one or more aerosol formers. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as propylene glycol, polyethylene glycol, triethylene glycol, 1,3-butanediol and glycerin), 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). It may be particularly preferred that the aerosol former is or includes glycerin. Optionally, the aerosol-forming substrate includes one or both of glycerin and glycerol.

[0095] Optionally, the substrate comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55% by weight of the aerosol former on a dry weight basis. Optionally, the substrate comprises no more than 55, 50, 45, 40, 35, 30, 25, 20, or 15% by weight of the aerosol former on a dry weight basis. Optionally, the substrate comprises 7-60, 10-60, 20-60, 30-60, 40-60, 50-60, 7-50, 10-50, 20-50, 30-50, 40-50, 7-40, 10-40, 20-40, 30-40, 7-30, 10-30, 20-30, 7-20, 10-20, or 7-10% by weight of the aerosol former on a dry weight basis. It may be particularly preferred for the substrate to contain from 15 to 25 weight percent of the aerosol former on a dry weight basis.

[0096] Optionally, the substrate comprises at least 2, 4, 6, 8, 10, 12, 14, 16, or 18 weight percent fibers on a dry weight basis. Optionally, the substrate comprises no more than 20, 18, 16, 14, 12, 10, 8, 6, or 4 weight percent fibers on a dry weight basis. Optionally, the substrate comprises 4-20, 6-20, 8-20, 10-20, 12-20, 14-20, 16-20, 18-20, 2-18, 4-18, 6-18, 8-18, 10-18, 12-18, 14-18, 16-18, 2-16, 4-16, 6-16, 8-16, 10- 16, 12-16, 14-16, 2-14, 4-14, 6-14, 8-14, 10-14, 12-14, 2-12, 4-12, 6-12, 8-12, 10-12, 2-10, 4-10, 6-10, 8-10, 2-8, 4-8, 6-8, 2-6, 4-6, or 2-4 wt. % fibers. It may be particularly preferred for the substrate to comprise 2.1 to 9.8 wt. % fibers, on a dry weight basis.

[0097] The aerosol-forming body may be glycerin. The aerosol-forming substrate may comprise at least 1, 2, 5, 10, or 15 percent by weight of glycerin. For example, the aerosol-forming substrate may comprise 12 to 25 percent by weight of glycerin.

[0098] The aerosol-forming material may include fibers, preferably 2 to 20% by weight of fibers.The aerosol-forming material may include a binder, preferably 2 to 10% by weight of binder.

[0099] Optionally, the substrate comprises at least 2, 4, 6, 8, 10, 12, 14, 16, or 18 weight percent fibers on a dry weight basis. Optionally, the substrate comprises no more than 20, 18, 16, 14, 12, 10, 8, 6, or 4 weight percent fibers on a dry weight basis. Optionally, the substrate comprises 4-20, 6-20, 8-20, 10-20, 12-20, 14-20, 16-20, 18-20, 2-18, 4-18, 6-18, 8-18, 10-18, 12-18, 14-18, 16-18, 2-16, 4-16, 6-16, 8-16, 10- 16, 12-16, 14-16, 2-14, 4-14, 6-14, 8-14, 10-14, 12-14, 2-12, 4-12, 6-12, 8-12, 10-12, 2-10, 4-10, 6-10, 8-10, 2-8, 4-8, 6-8, 2-6, 4-6, or 2-4 wt. % fibers. It may be particularly preferred for the substrate to comprise 2.1 to 9.8 wt. % fibers, on a dry weight basis.

[0100] Optionally, the fibers are cellulose fibers. Advantageously, cellulose fibers are inexpensive and can increase the tensile strength of the substrate.

[0101] Optionally, each of the fibers has three mutually orthogonal dimensions, and the largest dimension in the third dimension is at least 1.5, 2, 3, 5, 10, or 20 times greater than the smallest dimension in the third dimension. Optionally, each of the fibers has three mutually orthogonal dimensions, and the largest dimension in the third dimension is at least 1.5, 2, 3, 5, 10, or 20 times greater than the second largest dimension in the third dimension.

[0102] Optionally, the substrate comprises at least 4, 6, or 8% by weight of binder on a dry weight basis. Optionally, the substrate comprises no more than 8, 6, or 4% by weight of binder on a dry weight basis. Optionally, the substrate comprises 4-10, 6-10, 8-10, 2-8, 4-8, 6-8, 2-6, 4-6, 2-4% by weight of binder on a dry weight basis. It may be particularly preferred that the substrate comprises 2.1-10% by weight of binder on a dry weight basis.

[0103] Preferred binders are well known in the art and include, but are not limited to, natural pectins (such as fruit pectins, citrus pectins, or tobacco pectins), guar gums (such as hydroxyethyl guar and hydroxypropyl guar), locust bean gums (such as hydroxyethyl and hydroxypropyl locust bean gums), alginates, starches (such as modified or derivatized starches), celluloses (such as methylcellulose, ethylcellulose, ethylhydroxymethylcellulose, and carboxymethylcellulose), tamarind gum, dextran, pralon, konjac flour, xanthan gum, and the like. It may be particularly preferred that the binder is or comprises guar. It may be particularly preferred that the binder comprises or consists of one or more of carboxymethylcellulose or hydroxypropylcellulose, or a gum such as guar gum.

[0104] The aerosol-forming material may comprise nicotine. Optionally, the aerosol-forming substrate comprises at least 0.01, 1, 2, 3 or 4% by weight of nicotine on a dry weight basis. Optionally, the aerosol-forming substrate comprises no more than 5, 4, 3, 2 or 1% by weight of nicotine on a dry weight basis. Optionally, the aerosol-forming substrate comprises 0.01-5, 1-5, 2-5, 3-5, 4-5, 0.01-4, 1-4, 2-4, 3-4, 0.01-3, 1-3, 2-3, 0.01-2, 1-2, 0.01-1% by weight of nicotine on a dry weight basis. It may be particularly preferred that the aerosol-forming substrate comprises 0.5-3% by weight of nicotine on a dry weight basis.

[0105] Optionally, the nicotine is substantially uniformly distributed throughout the aerosol-forming material.

[0106] Optionally, the aerosol-forming material comprises an acid. Optionally, the aerosol-forming substrate comprises at least 0.01, 1, 2, 3, or 4% by weight of acid on a dry weight basis. Optionally, the aerosol-forming substrate comprises no more than 5, 4, 3, 2, or 1% by weight of acid on a dry weight basis. Optionally, the aerosol-forming substrate comprises 0.01-5, 1-5, 2-5, 3-5, 4-5, 0.01-4, 1-4, 2-4, 3-4, 0.01-3, 1-3, 2-3, 0.01-2, 1-2, 0.01-1% by weight of acid on a dry weight basis. It may be particularly preferred that the aerosol-forming substrate comprises 0.5-3% by weight of acid on a dry weight basis.

[0107] Optionally, the acid comprises or consists of one or more of fumaric acid, lactic acid, benzoic acid, and levulinic acid.

[0108] Optionally, the acid is distributed substantially uniformly throughout the aerosol-forming material.

[0109] Optionally, the aerosol-forming material comprises at least one plant component. Optionally, the substrate comprises at least 0.01, 1, 2, 5, 10, or 15% by weight, on a dry weight basis, of at least one plant component. Optionally, the substrate comprises no more than 20, 15, 10, 5, 2, or 1% by weight, on a dry weight basis, of at least one plant component. Optionally, the substrate comprises 0.01-20, 1-20, 2-20, 5-20, 10-20, 15-20, 0.01-15, 1-15, 2-15, 5-15, 10-15, 0.01-10, 1-10, 2-10, 5-10, 0.01-5, 1-5, 2-5, 0.01-2, 1-2, 0.01-1% by weight, on a dry weight basis, of at least one plant component. It may be particularly preferred that the substrate comprises from 5 to 15% by weight, on a dry weight basis, of at least one plant component.

[0110] Optionally, the at least one botanical ingredient comprises or consists of one or both of cloves and 1316comprises16s.

[0111] Optionally, the at least one botanical component is substantially uniformly distributed throughout the aerosol-forming material.

[0112] Optionally, the aerosol-forming material comprises at least one flavourant. Optionally, the aerosol-forming substrate comprises at least 0.1, 1, 2 or 5% by weight, on a dry weight basis, of at least one flavourant. Optionally, the aerosol-forming substrate comprises up to 10, 5, 2 or 1% by weight, on a dry weight basis, of at least one flavourant. Optionally, the aerosol-forming substrate comprises 0.1-10, 1-10, 2-10, 5-10, 0.1-5, 1-5, 2-5, 0.1-2, 1-2, 0.1-1% by weight, on a dry weight basis, of at least one flavourant. It may be particularly preferred that the substrate comprises 0.5-4.0% by weight, on a dry weight basis, of at least one flavourant.

[0113] Optionally, the at least one flavourant is present as a coating, for example a coating on one or more other components of the aerosol-forming substrate. Alternatively, or additionally, the at least one flavourant is substantially uniformly distributed throughout the aerosol-forming formulation.

[0114] Optionally, the aerosol-forming material includes at least one organic material, such as tobacco. Optionally, the at least one organic material includes at least one of herb leaves, tobacco leaves, tobacco stem 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 material.

[0115] The aerosol-forming substrate may contain less than 10, 5, 3, 2 or 1% by weight of tobacco on a dry weight basis.Optionally, the aerosol-forming substrate is a tobacco-free aerosol-forming substrate.

[0116] The aerosol-forming material may comprise or be in the form of one or more sheets, e.g., a collection of one or more sheets. The sheet or each sheet, e.g., a collection of sheets, may have a width of at least about 10, 25, 50, or 100 millimeters. The sheet or each sheet, e.g., a collection of sheets, may have a length of at least about 3, 5, or 10 millimeters. The sheet or each sheet, e.g., a collection of sheets, may have a thickness of at least about 100, 150, or 200 microns. The sheet or each sheet, e.g., a collection of sheets, may have a thickness of less than about 500, 400, or 300 microns. The sheet or each sheet, e.g., a collection of sheets, may have a thickness of 100 to 500, 170 to 400, or 200 to 300 microns. The sheet or each sheet, e.g., a collection of sheets, may have a thickness of about 235 microns.

[0117] According to a second aspect, a rod is provided. The rod may be a rod for an aerosol-generating article. The rod may comprise an aerosol-forming substrate or may be formed by an aerosol-forming substrate. In other words, a rod of an aerosol-forming substrate may be provided. The rod may comprise an assembly of sheets of an aerosol-forming substrate.

[0118] The rod may comprise a wrapper encasing an assembly of sheets of the aerosol-forming substrate. The aerosol-forming substrate is preferably an aerosol-forming substrate according to the first aspect. Thus, the rod may be formed by assembling co-laminate sheets of the first aspect.

[0119] The susceptor element may be located within the rod of the aerosol-forming substrate. The susceptor element may be an elongated susceptor element. The susceptor element may extend longitudinally within the rod of the aerosol-forming substrate. The rod may be substantially cylindrical, e.g., substantially right cylindrical in shape. The susceptor element may be located at a radially central position within the rod of the aerosol-forming substrate. The susceptor element may extend along a central longitudinal axis of the rod of the aerosol-forming substrate.

[0120] The susceptor element may extend all the way to the downstream end of the rod of the aerosol-forming substrate. The susceptor element may extend all the way to the upstream end of the rod of the aerosol-forming substrate. The susceptor element may have substantially the same length as the rod of the aerosol-forming substrate. The susceptor element may extend all the way from the upstream end to the downstream end of the rod of the aerosol-forming substrate.

[0121] The susceptor elements may be in the form of pins, rods, strips, or blades.

[0122] The susceptor element may have a length of 5 to 15, 6 to 12, or 8 to 10 millimeters. The susceptor element may have a width of 1 to 5 millimeters. The susceptor element may have a thickness of 0.01 to 2, 0.5 to 2, or 0.5 to 1 millimeters.

[0123] Alternatively, there may be no susceptor material present within the aerosol-forming substrate or within the rod of the aerosol-forming substrate. Or, the layer of carbon-based thermally conductive material may comprise or consist of one or more susceptor materials and may be the only susceptor material present within the aerosol-forming substrate or within the rod of the aerosol-forming substrate. That is, there may be no susceptor elements present within the aerosol-forming substrate or within the rod of the aerosol-forming substrate, except for the layer of thermally conductive material.

[0124] Suitable susceptor materials include, but are not limited to, for example, carbon, carbon-based materials, graphene, graphite, expanded graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metal materials. Suitable susceptor materials may include ferromagnetic materials, such as ferritic iron, ferromagnetic alloys such as ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrites. Suitable susceptor materials may be or include aluminum. The susceptor material preferably includes more than 5% ferromagnetic or paramagnetic material, preferably more than 20% ferromagnetic or paramagnetic material, and more preferably more than 50% or more than 90% ferromagnetic or paramagnetic material. Preferred susceptor materials may include metals, metal alloys, or carbon.

[0125] Particularly preferred susceptor materials may be or include carbon, carbon-based materials, graphene, graphite, or expanded graphite. Advantageously, such materials have relatively high thermal conductivity, relatively low density, and may be inductively heated. These materials may be preferred when the layer of carbon-based thermally conductive material acts as a susceptor or includes a material that acts as a susceptor.

[0126] As described in more detail below with reference to the aerosol-generating system, in use the susceptor material may convert electromagnetic energy into heat, which may heat the aerosol-forming material in the aerosol-forming substrate.

[0127] The aerosol-forming substrate may have a longitudinal direction and a transverse or radial direction perpendicular to the longitudinal direction. For example, the aerosol-forming substrate may be in the form of a plug. The plug may be in the shape of a right cylinder. The plug may have a length extending in the longitudinal direction and a radius extending in the transverse or radial direction. The longitudinal direction may refer to a direction extending from an upstream end to a downstream end of the substrate, or from an upstream end to a downstream end of an article of which the substrate is a part. The aerosol-forming substrate may have a thermal conductivity at 25 degrees Celsius in at least one direction of greater than 0, 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 / (mK).

[0128] Advantageously, increasing the thermal conductivity of the substrate may reduce temperature gradients in the substrate during use. Increasing the thermal conductivity of the substrate in the transverse direction may be particularly advantageous since large temperature gradients typically exist in the transverse direction in prior art substrates when used with heating blades.

[0129] According to a third aspect of the present disclosure, there is provided an aerosol-generating article comprising an aerosol-forming substrate. Any of the features described above in relation to the aerosol-forming substrate may be applicable to the aerosol-forming substrate of the aerosol-generating article.

[0130] The aerosol-generating article may be for use with an electrical aerosol generating device.

[0131] The aerosol-generating article may comprise a plurality of elements. The plurality of elements may be assembled in the form of a rod. The plurality of elements may be assembled within a wrapper or casing. The aerosol-generating article may have a length of from 30mm to 120mm, such as from 40 to 80mm, for example about 45mm. The aerosol-generating article may have a diameter of from 3.5mm to 10mm, such as from 4mm to 8.5mm, for example from 4.5mm to 7.5mm.

[0132] The plurality of elements may include an upstream element. The plurality of elements may include an aerosol-forming substrate. The plurality of elements may include a support element. The plurality of elements may include an aerosol cooling element. The plurality of elements may include a mouthpiece element.

[0133] The aerosol-generating article may comprise an intermediate aerial section. The intermediate aerial section may be located between the rod of the aerosol-generating substrate and the mouthpiece element. The intermediate hollow section may include one or both of a support element and an aerosol cooling element. The intermediate hollow section may consist of one or both of a support element and an aerosol cooling element.

[0134] The upstream element may be located at the upstream end of the article. The aerosol-forming substrate may be located downstream, e.g. immediately downstream of the upstream element. Alternatively, the aerosol-forming substrate may be located at the upstream end of the article, e.g. when no upstream element is present. The support element may be located downstream, e.g. immediately downstream of the aerosol-forming substrate. The aerosol-cooling element may be located downstream, e.g. immediately downstream of the support element. The mouthpiece element may be located downstream, e.g. immediately downstream of the aerosol-cooling element. The mouthpiece element may be located at the downstream or mouth end of the article.

[0135] The upstream element may advantageously prevent direct physical contact with the upstream end of the aerosol-forming substrate. The upstream element may also advantageously reduce the likelihood of material from the aerosol-forming substrate falling off the article. The support element may advantageously provide support to the article and help to properly position other components of the article. The aerosol cooling element may advantageously allow for cooling the aerosol so that it is at a more desirable temperature when it reaches the user. The mouthpiece element may advantageously act as a filter.

[0136] The multiple components of the aerosol-generating article may be assembled by means of a suitable wrapper, such as cigarette paper. The cigarette paper may be any material suitable for packaging the components of the aerosol-generating article in the form of a rod. Suitable materials for wrappers are well known in the art. The cigarette paper may grip the component components of the aerosol-generating article when the article is assembled. The cigarette paper may hold the component components in place within the rod.

[0137] The upstream element may be in the form of a plug, e.g. a porous plug. The upstream element may comprise one or more longitudinally extending cavities. The upstream element may comprise a slit or opening. The slit or opening may extend from the upstream end to the downstream end of the upstream element. The slit of the opening may be suitable to allow a heating pin, rod or blade to pass through in use. The upstream element may be made of a porous material. The upstream element may be made of the same material as that used for one of the other components of the aerosol-generating article, such as the mouthpiece element, the aerosol cooling element or the support element. The upstream element may comprise or be formed from one or more of a filter material, a ceramic, a polymeric material, cellulose acetate, cardboard, a zeolite or an aerosol-generating substrate. It may be preferred that the upstream element comprises or is formed from a plug of cellulose acetate, e.g. cellulose acetate.

[0138] Optionally, the front plug has a length of from 2 to 10, 3 to 8, or 4 to 6 mm, for example about 5 mm. Optionally, the aerosol-forming substrate within the article has a length of from 5 to 20, 8 to 15, or 10 to 15 mm, for example about 12 mm.

[0139] The upstream element may have a length of 1 to 10 millimeters, 3 to 8 millimeters, or 4 to 6 millimeters. The upstream element may have a length of about 5 millimeters.

[0140] Advantageously, the upstream element may prevent a consumer from seeing the layer of thermally conductive material through the upstream end of the article.

[0141] The support element may include or may be a hollow tube, such as a substantially cylindrical hollow tube. The hollow tube may define an interior cavity. The interior cavity may extend along a longitudinal axis. Airflow through the interior cavity may be substantially unrestricted. Thus, the hollow tube may not substantially contribute to the resistance to withdrawal (RTD) of the article. The wall thickness of the hollow tube may be between 2 and 4 millimeters.

[0142] The support element may be formed from any suitable material or combination of materials. For example, the support element may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). In a preferred embodiment, the support element is formed from cellulose acetate. Other suitable materials include polyhydroxyalkanoate (PHA) fibers. It may be particularly preferred that the support element includes or is formed from cellulose acetate.

[0143] The support element may have an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The support element may have an outer diameter of 5 to 12, 5 to 10, or 5 to 8, 6 to 12, 6 to 10, or 6 to 8 millimeters. The support element may have an outer diameter of approximately 7.2 millimeters.

[0144] The peripheral wall of the support element may have a thickness of at least 1, 1.5, or 2 millimeters, for example when the support element includes or is a second hollow tube.

[0145] The support elements may have a length of at least 5, 6, 7, or 8 millimeters. Alternatively, or in addition, the support elements may have a length of less than 15, 12, or 10 millimeters.

[0146] The aerosol cooling element may include or may be a second hollow tube, such as a substantially cylindrical second hollow tube. The second hollow tube may define a second internal cavity. The second internal cavity may extend in a longitudinal direction. Airflow through the second internal cavity may be substantially unrestricted. Thus, the second hollow tube may not substantially contribute to the resistance to draw (RTD) of the article. The wall thickness of the second hollow tube may be between 1 and 3 millimeters.

[0147] The aerosol cooling element may include or be formed from any suitable material or combination of materials. For example, the aerosol cooling element may include or be formed from one or more materials selected from the list consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). Other suitable materials include polyhydroxyalkanoate (PHA) fibers. It may be preferred that the aerosol cooling element includes or is formed from cellulose acetate.

[0148] The aerosol cooling element may have an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The aerosol cooling element may have an outer diameter of 5 to 12, 5 to 10, or 5 to 8, 6 to 12, 6 to 10, or 6 to 8 millimeters. The aerosol cooling element may have an outer diameter of approximately 7.2 millimeters.

[0149] The aerosol cooling element may have an inner diameter of at least about 2, 2.5, or 3 millimeters, for example, when the aerosol cooling element includes or is a second hollow tube.

[0150] The peripheral wall of the aerosol cooling element may have a thickness of less than about 2.5, 1.5, 1.25, 1, 0.9, or 0.8 millimeters, for example, when the aerosol cooling element includes or is a second hollow tube.

[0151] The aerosol cooling element may have a length of at least 5, 6, 7, or 8 millimeters. Alternatively, or in addition, the aerosol cooling element may have a length of less than 15, 12, or 10 millimeters.

[0152] The mouthpiece element may comprise a filtration material, for example a fibrous filtration material. The mouthpiece element may include or be a plug of cellulose acetate. The mouthpiece element may be translucent or opaque.

[0153] The mouthpiece element may have an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The mouthpiece element may have an outer diameter of 5 to 12, 5 to 10, or 5 to 8, 6 to 12, 6 to 10, or 6 to 8 millimeters. The mouthpiece element may have an outer diameter of approximately 7.2 millimeters.

[0154] The mouthpiece element may have a length of at least 5, 8, or 10 millimeters. Alternatively, or additionally, the mouthpiece element may have a length of less than 25, 20, or 15 millimeters. The mouthpiece element may have a length of approximately 12 millimeters.

[0155] Advantageously, a longer mouthpiece element may be more resilient to deformation or may be more adapted to recover its initial shape after deformation, and may provide an improved grip by the consumer to facilitate insertion of the aerosol-generating article into the heating device. Additionally, a longer mouthpiece element may provide a higher level of filtration and removal of undesirable aerosol components, thereby delivering a higher quality aerosol. Additionally, the use of a longer mouthpiece element allows for more complex mouthpieces to be provided, since there is more space to incorporate mouthpiece components such as capsules, threads, and restrictors.

[0156] The aerosol-generating article may have an overall length of 38-70, 40-70, 42-70, 38-60, 40-60, or 42-60, 38-50, 40-50, or 42-50 millimeters. The aerosol-generating article may have an overall length of about 45 millimeters.

[0157] The aerosol-generating article may have an outer diameter of at least about 5, 6, or 7 millimeters.The aerosol-generating article may have an outer diameter of less than about 12, 10, or 8 millimeters.The aerosol-generating article may have an outer diameter of about 7.2 millimeters.

[0158] According to the present disclosure, there is provided an aerosol generating system comprising the aerosol generating article and aerosol generating device described above.

[0159] The aerosol generating device may be an electrical aerosol generating device. The aerosol generating device may be engageable with and disengageable from the aerosol generating article. For example, the aerosol generating device may be configured to receive at least a portion of the aerosol generating article.

[0160] The aerosol generating device may be configured to heat the aerosol-generating article. The aerosol-generating article may be configured to resistively heat the aerosol generating device. The device may comprise a heating element. The heating element may be configured to contact, e.g. penetrate, the aerosol-forming substrate in use. The heating element may be configured to be resistively heated. The heating element may comprise an electrically resistive track. In use, an electric current may be passed through the track to resistively heat it. The heating element may be in the form of a pin, rod or blade.

[0161] The aerosol-generating device may be configured to inductively heat the aerosol-generating article. The device may comprise an inductor, such as an induction coil. The device may be configured to generate a fluctuating electromagnetic field. In use, this fluctuating electromagnetic field may induce eddy currents in a susceptor material, e.g. a thermally conductive material, or in a susceptor material of a heating element of the device, or both. If the device comprises an inductively heatable heating element, such heating element may be configured to contact, e.g. penetrate, the aerosol-forming substrate in use. The heating element may be in the form of a pin, rod or blade. The eddy currents may heat the susceptor material, thereby heating the aerosol-forming substrate in use.

[0162] In a fourth aspect of the present disclosure, a method of forming an aerosol-forming substrate is provided.

[0163] The method may include combining a layer of an aerosol-forming material with a layer of a carbon-based thermally conductive material to form a co-laminate sheet. The aerosol-forming substrate produced using this method may have the characteristics described in relation to the first embodiment.

[0164] The layer of aerosol-forming material may be a continuous sheet of aerosol-forming material. The layer of carbon-based thermally conductive material may be a continuous sheet of carbon-based thermally conductive material. In such cases, the method may include forming a continuous co-laminate sheet.

[0165] The method may further include assembling the co-laminate sheets transversely to their longitudinal axes. The method may further include encasing the assembly of co-laminate sheets in a wrapper to form a rod.

[0166] If the method includes forming a continuous co-laminate sheet, the assembly of the wrapped sheets may form a continuous rod, in which case the method may further include cutting the continuous rod into a plurality of individual rods.

[0167] Such rods can be used as aerosol-forming substrates in heated aerosol-generating articles. The aerosol-generating article is preferably a smoking article that generates an aerosol that can be inhaled directly through the user's mouth into the user's lungs. More preferably, the aerosol-generating article is a smoking article that generates a nicotine-containing aerosol that can be inhaled directly through the user's mouth into the user's lungs.

[0168] The step of combining the layers may include placing the layer of carbon-based thermally conductive material and the layer of aerosol-forming material in contact with each other, preferably in intimate contact. The method may crimp the layer of carbon-based thermally conductive material and the layer of aerosol-forming material, such that the layers are in contact with each other. This may include feeding the layer of carbon-based thermally conductive material and the layer of aerosol-forming material through a crimping roller. The crimping roller may engage and crimp the layers together to form a continuous crimped co-laminate sheet. The crimped co-laminate sheet may have a plurality of interspaced ridges or corrugations substantially parallel to the longitudinal axis of the sheet.

[0169] The term "crimped" as used herein is intended to be synonymous with the term "crinkled" and refers to a sheet with a plurality of substantially parallel ridges or corrugations. Preferably, the crimped sheet of homogenized tobacco material has a plurality of ridges or corrugations that are substantially parallel to the cylindrical axis of the rod. This advantageously facilitates assembly of the crimped sheet of homogenized tobacco material to form a rod. However, it will be understood that the crimped sheet of homogenized tobacco material used in the present invention may alternatively, or in addition, have a plurality of substantially parallel ridges or corrugations that are arranged at an acute or obtuse angle relative to the cylindrical axis of the rod.

[0170] The step of combining the layers may include layering a sheet of carbon-based thermally conductive material over a sheet of aerosol-forming material.

[0171] Alternatively, the step of combining the sheets may include layering a sheet of the aerosol-forming material onto a sheet of the carbon-based thermally conductive material.

[0172] In either case, a continuous process may be advantageously achieved by feeding one of the sheets of carbon-based thermally conductive material or aerosol-forming material from a first bobbin onto a conveyor, and the other sheet of carbon-based thermally conductive material or aerosol-forming material may be fed from the first bobbin onto the conveyor from a second bobbin on top of the sheet.

[0173] Optionally, the method further comprises the step of forming a layer of aerosol-forming material. Forming the layer of aerosol-forming material may comprise a step of a papermaking process, or preferably a casting process.

[0174] The step of forming the layer of aerosol-forming material may include casting a slurry including an organic material, preferably a homogenized tobacco material.

[0175] The step of forming a sheet further includes drying the slurry to form an aerosol-forming material.

[0176] The step of forming a layer of aerosol-forming material may be performed prior to the step of combining the layers and may include layering a sheet of carbon-based thermally conductive material onto the sheet of aerosol-forming material.

[0177] Alternatively, the step of forming the layer of aerosol-forming material may be performed simultaneously with the step of combining the layers and may include overlaying a sheet of carbon-based thermally conductive material onto the sheet of aerosol-forming material. In particular, the sheet of aerosol-forming material may be formed on the sheet of carbon-based thermally conductive material. Preferably, a slurry of the aerosol-forming material may be cast, preferably directly, onto the carbon-based thermally conductive material. The slurry may be on the carbon-based thermally conductive material and allowed to dry. In this way, the co-laminate sheet may be formed simultaneously with providing the layer of aerosol-forming material. This is particularly advantageous in a continuous process that improves the speed and ease of manufacturing the co-laminate sheet.

[0178] Additionally, the process of casting the aerosol-forming material often requires casting the slurry onto a support structure, however, casting a layer of the aerosol-forming material onto a carbon-based thermally conductive material may advantageously eliminate the need for an additional support structure.

[0179] The slurry preferably comprises an aerosol former, reinforcing fibers, and a binder, the characteristics of which are described in the first embodiment as characteristics of the aerosol-forming material.

[0180] Optionally, forming the slurry includes adding fibers.

[0181] Optionally, the method, e.g., the step of forming a slurry, includes first mixing the slurry. Optionally, the first mixing is performed under a first pressure of less than or equal to 500, 400, 300, 250, or 200 mbar. Optionally, the first mixing is performed for 1 to 10, 2 to 8, or 3 to 6 minutes, e.g., about 4 minutes.

[0182] Optionally, the method, e.g., forming a slurry, includes a second mixing step after the first mixing. Optionally, the second mixing step is performed under a second pressure that is less than the first pressure. Optionally, the second pressure is less than or equal to 500, 400, 300, 200, 150, or 100 mbar. Optionally, the second mixing step is performed for 5 to 120, 5 to 80, 5 to 40, or 10 to 30 seconds, e.g., about 20 seconds.

[0183] Casting the slurry may include casting the slurry onto a flat support, such as a steel plate. Alternatively, the slurry may be cast directly onto a sheet or layer of carbon-based thermally conductive material, as described above.

[0184] Optionally, after casting the slurry and before drying the slurry, the method may include setting the thickness of the slurry, for example setting the thickness of the slurry to between 100 and 1200, between 200 and 1000, between 300 and 900, between 500 and 700 microns, for example about 600 microns.

[0185] Optionally, drying the slurry includes providing a flow of gas, such as air, over or through the slurry. Optionally, the flow of gas is heated. Optionally, the flow of gas is heated to a temperature of 100-160 degrees Celsius, or 120-140 degrees Celsius. Optionally, the flow of gas is provided for 1-10 minutes, or 2-5 minutes. Optionally, drying the slurry includes drying the slurry until the slurry has a moisture content of 1-20%, 2-15%, 2-10%, or 3-7% by weight.

[0186] Optionally, drying the slurry forms a precursor for forming into a sheet of aerosol-forming material.

[0187] Optionally, the method includes cutting the sheet of aerosol-forming material to form individual pieces of aerosol-forming material. In a continuous process, the step of cutting the sheet of aerosol-forming material may be the same step as cutting a continuous rod to form individual rods.

[0188] Alternatively or additionally, the method of the fourth aspect may include forming a layer of carbon-based thermally conductive material, which may include preparing, forming or manufacturing a reconstituted carbon-based material.

[0189] The process of producing the reconstituted carbon-based material may include forming a slurry including the thermally conductive particles. The process of producing the reconstituted carbon-based material may additionally include casting and drying the slurry to form the reconstituted carbon-based material.

[0190] The slurry may preferably include fibers. The slurry may preferably include a binder. The presence of fibers and / or a binder in the slurry may increase the tensile strength of the cast and dried slurry.

[0191] Optionally, the slurry may include an aerosol former.

[0192] Optionally, the slurry comprises water. Optionally, the slurry comprises 20-90, 30-90, 40-90, 40-85, 50-80, 60-80, or 60-75% by weight water.

[0193] Optionally, forming the slurry includes forming a first mixture. The first mixture may include fibers. The first mixture may include water. The first mixture may include an aerosol former.

[0194] Forming the slurry can include forming a second mixture. The second mixture can include thermally conductive particles. The second mixture can include a binder. Forming the slurry can include adding the second mixture to the first mixture to form a combined mixture.

[0195] Optionally, the method, e.g., forming a slurry, includes a first mixing of the combined mixture. Optionally, the first mixing is performed under a first pressure of less than or equal to 500, 400, 300, 250, or 200 mbar. Optionally, the first mixing is performed for 1 to 10, 2 to 8, or 3 to 6 minutes, e.g., about 4 minutes.

[0196] Optionally, the method, e.g., forming a slurry, includes a second mixing step after the first mixing. Optionally, the second mixing step is performed under a second pressure that is less than the first pressure. Optionally, the second pressure is less than or equal to 500, 400, 300, 200, 150, or 100 mbar. Optionally, the second mixing step is performed for 5 to 120, 5 to 80, 5 to 40, or 10 to 30 seconds, e.g., about 20 seconds.

[0197] Optionally, casting the slurry includes casting the slurry onto a flat support, such as a steel plate flat support.

[0198] Optionally, after casting the slurry and before drying the slurry, the method includes setting a thickness of the slurry, for example setting a thickness of the slurry to between 100 and 1200, between 200 and 1000, between 300 and 900, between 500 and 700 microns, for example about 600 microns.

[0199] Optionally, drying the slurry includes providing a flow of gas, such as air, over or through the slurry. Optionally, the flow of gas is heated. Optionally, the flow of gas is heated to a temperature of 100-160 degrees Celsius, or 120-140 degrees Celsius. Optionally, the flow of gas is provided for 1-10 minutes, or 2-5 minutes. Optionally, drying the slurry includes drying the slurry until the slurry has a moisture content of 1-20%, 2-15%, 2-10%, or 3-7% by weight.

[0200] In a fifth aspect of the present disclosure, there is provided a method of forming a rod comprising an aerosol-forming substrate, the method comprising the steps of: providing a co-laminate sheet comprising a layer of an aerosol-forming material and a layer of a carbon-based thermally conductive material; Assembling the co-laminate sheets transversely to their longitudinal axes; and wrapping the collection of co-laminate sheets in a wrapper to form a continuous rod.

[0201] The method of the fifth aspect may further comprise any of the steps of the method of the fourth aspect.

[0202] In a sixth aspect, there is provided a method of forming an aerosol-generating article comprising the method steps of the fifth aspect.

[0203] The method includes assembling an aerosol-generating article from a plurality of components, the plurality of components including an aerosol-forming substrate.

[0204] Such an article may for example be in the form of a rod which may comprise multiple components including the aerosol-forming substrate assembled within a wrapper or casing. The aerosol-generating article may have a length of from 30mm to 120mm, such as from 40 to 80mm, for example about 45mm. The aerosol-generating article may have a diameter of from 3.5mm to 10mm, such as from 4mm to 8.5mm, for example from 4.5mm to 7.5mm.

[0205] Optionally, the aerosol-generating article comprises a front plug. Optionally, the aerosol-generating article comprises a first hollow tube, e.g., a first hollow acetate tube. Optionally, the aerosol-generating article comprises a second hollow tube, e.g., a second hollow acetate tube. Optionally, the second hollow tube comprises one or more vent holes. Optionally, the aerosol-generating article comprises a mouth plug filter. Optionally, the aerosol-generating article comprises a wrapper, e.g., a paper wrapper.

[0206] Optionally, the front plug is disposed at the most upstream end of the article. Optionally, the aerosol-forming substrate is disposed downstream of the front plug. Optionally, the first hollow tube is disposed downstream of the aerosol-forming substrate. Optionally, the second hollow tube is disposed downstream of the first hollow tube. Optionally, the mouth plug filter is disposed downstream of one or both of the first hollow tube and the second hollow tube. Optionally, the mouth plug filter is disposed at the most downstream end of the article. Optionally, the most downstream end of the article, which may be referred to as the mouth end of the article, may be configured for insertion into the mouth of a user. A user may, for example, be able to directly inhale the mouth end of the article.

[0207] Optionally, the front plug, the aerosol-forming substrate, one or both of the first and second hollow tubes, and the mouth plug filter are enclosed by a wrapper, for example a paper wrapper.

[0208] Optionally, the front plug has a length of 2-10, 3-8, or 4-6 mm, such as about 5 mm. Optionally, the aerosol-forming substrate within the article has a length of 5-20, 8-15, or 10-15 mm, such as about 12 mm. Optionally, the first hollow tube has a length of 2-20, 5-15, or 5-10 mm, such as about 8 mm. Optionally, the second hollow tube has a length of 2-20, 5-15, or 5-10 mm, such as about 8 mm. Optionally, the mouth plug filter has a length of 5-20, 8-15, or 10-15 mm, such as about 12 mm. The length of one or more of the front plug, the aerosol-forming substrate, the first hollow tube, the second hollow tube, and the mouth plug filter may extend in a longitudinal direction.

[0209] One or more of the front plug, the aerosol-forming substrate, the first hollow tube, the second hollow tube and the mouth plug filter may be substantially cylindrical, for example in the shape of a right cylinder.

[0210] As would be understood by one of ordinary skill in the art upon reading this disclosure, features described herein in relation to one embodiment may be applicable to any other embodiment.

[0211] As used herein, the term "aerosol-forming substrate" may refer to a substrate capable of emitting an aerosol or volatile compound capable of forming an aerosol. Such a volatile compound may be emitted by heating the aerosol-forming substrate. The aerosol-forming substrate may comprise an aerosol-forming material. The aerosol-forming substrate may be adsorbed, coated, impregnated, or otherwise loaded onto a carrier or support. The aerosol-forming substrate may conveniently be part of an aerosol-generating article or a smoking article.

[0212] As used herein, the term "expanded graphite" may refer to a graphite-based material or a material having a graphite-like structure. Expanded graphite may have carbon layers (e.g., similar to graphite) where the spacing between the carbon layers is greater than the spacing found between the carbon layers in regular graphite. Expanded graphite may have carbon layers with elements or compounds interposed in the spaces between the carbon layers.

[0213] As used herein, unless otherwise specified, the term "density" may be used to refer to true density. Measurement of true density can be performed using many standard methods, which are often based on Archimedes' principle. The most widely used method, when used to measure the true density of a powder, involves placing the powder in a container of known volume (pycnometer) and measuring its weight. The pycnometer is then filled with a fluid of known density in which the powder is not soluble. The volume of the powder is determined by the difference between the volume indicated by the pycnometer and the volume of the liquid added (i.e., the volume of air displaced).

[0214] As used herein, the term "aerosol-generating article" may refer to an article that is capable of generating or releasing an aerosol, for example when heated.

[0215] As used herein, the term "longitudinal" may refer to the direction extending between a downstream or proximal end and an upstream or distal end of a component, such as an aerosol-forming substrate or an aerosol-generating article.

[0216] As noted above, the term "transverse" may refer to a direction perpendicular to the longitudinal direction.

[0217] As used herein, the term "aerosol-generating device" may refer to a device used in conjunction with an aerosol-generating article to enable the generation or emission of an aerosol.

[0218] As used herein, the term "sheet" can refer to a generally planar, laminar element having a width and length substantially greater than, for example, at least 2, 3, 5, 10, 20, or 50 times its thickness.

[0219] The term "aerosol former" as used herein may refer to any suitable known compound or mixture of compounds that facilitates the formation of an aerosol upon use. The aerosol may be a dense, stable aerosol. The aerosol may be substantially resistant to thermal decomposition at the operating temperature of the aerosol-forming substrate or aerosol-generating article.

[0220] The term "rod" as used herein may refer to an element that is generally cylindrical, eg, right cylindrical, substantially circular, elliptical, or oval in cross section.

[0221] As used herein, the term "crimp" may refer to a sheet or individual element having one or more ridges or corrugations. The ridges or corrugations may be substantially parallel. When present in a component of an aerosol-generating article, the ridges or corrugations may extend longitudinally relative to the aerosol-generating article. EXAMPLES

[0222] The present invention is defined in the claims. However, below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more of the features of other examples, embodiments, or aspects described herein.

[0223] Example 1. An aerosol-forming substrate for use in a heated aerosol-generating article comprises a co-laminate sheet including a layer of an aerosol-forming material and a layer of a carbon-based thermally conductive material. Example 2. 2. The aerosol-forming substrate of claim 1, wherein the layer of carbon-based thermally conductive material is a material that includes or consists of one or more of the following: graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond. Example 3. 3. The aerosol-forming substrate of embodiment 1 or 2, wherein the layer of carbon-based thermally conductive material can comprise or consist of at least one of graphite and expanded graphite. Example 4. 4. The aerosol-forming substrate according to any one of Examples 1 to 3, wherein the width of the co-laminate sheet is greater than 10 mm, preferably greater than 20, 30, 40, 50, 60, 70, 80, 90, 100 millimeters. Example 5. An aerosol-forming substrate according to any one of Examples 1 to 4, wherein the width of the co-laminate sheet is less than 300, 250, 200, or 150 millimeters. Example 6. 6. The aerosol-forming substrate according to any one of Examples 1 to 5, wherein the layer of the aerosol-forming material of the co-laminate sheet is in close contact with the layer of the thermally conductive material. Example 7. 7. The aerosol-forming substrate according to any one of Examples 1 to 6, wherein the layer of carbon-based thermally conductive material has a length and width similar to or the same as the length and width of the layer of aerosol-forming material. Example 8. 8. The aerosol-forming substrate according to any one of Examples 1 to 7, wherein the layer of carbon-based thermally conductive material is in contact with the layer of aerosol-forming material over substantially the entire surface of the layer of thermally conductive material. Example 9. An aerosol-forming substrate according to any one of Examples 1 to 8, wherein the layers of the co-laminate sheet form a single sheet. Example 10. 10. The aerosol-forming substrate of any one of Examples 1 to 9, wherein the co-laminate sheet comprises two or more layers of an aerosol-forming material. Example 11. An aerosol-forming substrate according to any one of Examples 1 to 10, wherein the co-laminate sheet comprises two or more layers of thermally conductive material. Example 12. 11. An aerosol-forming substrate as described in example 10, wherein the or each layer of aerosol-forming material is sandwiched between layers of thermally conductive material. Example 13. 12. An aerosol-forming substrate as described in example 11, wherein the or each layer of thermally conductive material is sandwiched between layers of aerosol-forming material. Example 14. 14. The aerosol-forming substrate according to any one of claims 1 to 13, wherein the co-laminate sheet comprises a layer of a carbon-based thermally conductive material and one or more additional layers comprising a material other than the aerosol-forming material. Example 15. 15. An aerosol-forming substrate according to any one of Examples 1 to 14, wherein the or each layer of thermally conductive material is in the form of a film or foil. Example 16. 16. An aerosol-forming substrate according to any one of Examples 1 to 15, wherein the or each layer of thermally conductive material is flexible. Example 17. 17. The aerosol-forming substrate according to any one of Examples 1 to 16, wherein the or each layer of aerosol-forming material is flexible. Example 18. The aerosol-forming substrate according to any one of Examples 1 to 17, wherein the co-laminate sheet is flexible. Example 19. 19. The aerosol-forming substrate of any one of examples 1 to 18, wherein the or each layer of thermally conductive material has a thickness of less than 10, 5, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, or 0.02 millimeters. Example 20. 20. The aerosol-forming substrate according to any one of the preceding claims, wherein the or each layer of thermally conductive material has a thickness of 10 to 0.02, or 5 to 0.02, 3 to 0.02, 2 to 0.02, 1 to 0.02, 0.9 to 0.02, 0.8 to 0.02, 0.7 to 0.02, 0.6 to 0.02, 0.5 to 0.02, 0.4 to 0.02, 0.3 to 0.02, 0.2 to 0.02, 0.1 to 0.02, 0.09 to 0.02, 0.08 to 0.02, 0.07 to 0.02, 0.06 to 0.02, 0.05 to 0.02, 0.04 to 0.02 millimeters. Example 21. 21. The aerosol-forming substrate according to any one of the preceding embodiments, wherein the layer of carbon-based thermally conductive material comprises or consists of carbon fiber, graphite, or graphene. Example 22. 22. The aerosol-forming substrate of example 21, wherein the layer of carbon-based thermally conductive material comprises or consists of expanded graphite. Example 23. 23. The aerosol-forming substrate of example 21 or 22, wherein the layer of carbon-based thermally conductive material comprises both graphite and expanded graphite. Example 24. 24. The aerosol-forming substrate according to any one of embodiments 21 to 23, wherein the layer of carbon-based thermally conductive material consists of a foil or film of flexible graphite or flexible graphite and expanded graphite. Example 25. The aerosol-forming substrate according to any one of Examples 1 to 24, wherein the layer of the carbon-based thermally conductive material has a density equal to or lower than the density of the aerosol-forming material. Example 26. 26. The aerosol-forming substrate according to any one of examples 1 to 25, wherein the layer of thermally conductive material has a density that is at least 1, 2, 5, 10, 15, 20, 25, or 30% less than the density of the aerosol-forming material. Example 27. 27. The aerosol-forming substrate according to any one of examples 1 to 26, wherein the aerosol-forming substrate has a density of less than 1050, 1000, 950, 900, 850, 800, 850, 800, 750, 700, or 650 kg / m3. Example 28. The aerosol-forming substrate is 500 to 900 kg / m 3 , e.g., 600-800 kg / m 3 The aerosol-forming substrate according to any one of Examples 1 to 27, having a density of Example 29. The layers of carbon-based thermally conductive material were 3, 2, 1.8, 1.5, 1.2, 1, 0.8, 0.5, 0.2, 0.1, 0.05, and 0.02 grams per centimeter cubed (g / cm 3 29. The aerosol-forming substrate according to any one of Examples 1 to 28, having a density of less than 1 / 2. Example 30. The layer of carbon-based thermally conductive material was heated to 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, and 1.8 grams per centimeter cubed (g / cm 3 30. The aerosol-forming substrate according to any one of Examples 1 to 29, having a density greater than 100%. Example 31. The carbon-based thermally conductive material layer is 0.01-3, 0.01-2, 0.01-1.8, 0.01-1.5, 0.01-1.2, 0.01-1, 0.01-0.8, 0.01-0.5, 0.02-3, 0.02-2, 0.02-1.8, 0.02-1.5, 0.02-1.2, 0.02-1, 0.02-0.8, 0.02-0.5, 0.01-3, 0.05-2, 0.05-1.8, 0.05-1.5, 0.05-1.2, 0.05-1, 0.05-0.8, 0.05-0.5g / cm3, 0.1-3, 0.1-2, 0.1-1.8, 0.1- The aerosol-forming substrate according to any one of Examples 1 to 30, having a density of 1.5, 0.1 to 1.2, 0.1 to 1, 0.1 to 0.8, 0.1 to 0.5, 0.2 to 3, 0.2 to 2, 0.2 to 1.8, 0.2 to 1.5, 0.2 to 1.2, 0.2 to 1, 0.2 to 0.8, 0.2 to 0.5, 0.5 to 3, 0.5 to 2, 0.5 to 1.8, 0.5 to 1.5, 0.5 to 1.2, 0.5 to 1, 0.5 to 0.8, 0.8 to 3, 0.8 to 2, 0.8 to 1.8, 0.8 to 1.5, 0.8 to 1.2, or 0.8 to 1 grams per centimeter cube (g / cm3). Example 32. 32. The aerosol-forming substrate according to any one of examples 1 to 31, wherein the layer of carbon-based thermally conductive material has a tensile strength of greater than 1, 2, 3, 4, 5, 6, 7, 8, or 9 Megapascals (Mpa). Example 33. 33. An aerosol-forming substrate according to any one of examples 1 to 32, wherein the layer of carbon-based thermally conductive material comprises or consists of a reconstituted carbon-based material. Example 34. 34. The aerosol-forming substrate of example 33, wherein the layer of carbon-based thermally conductive material comprises or consists of a reconstituted graphite sheet. Example 35. 35. An aerosol-forming substrate as described in example 33 or 34, wherein the layer of carbon-based thermally conductive material comprises or consists of a reconstituted graphite film or foil. Example 36. 36. The aerosol-forming substrate according to any one of examples 33 to 35, wherein the reconstituted carbon-based material comprises thermally conductive particles. Example 37. 37. The aerosol-forming substrate of example 36, wherein each of the thermally conductive particles has a thermal conductivity of at least 1 Watt per meter Kelvin [W / (mK)] in at least one direction at 25 degrees Celsius. Example 38. 38. The aerosol-forming substrate of example 36 or 37, wherein some or all of the thermally conductive particles comprise carbon, e.g., at least 10, 30, 50, 70, 90, 95, 98, or 99% by weight carbon. Example 39. The aerosol-forming substrate of any one of examples 33 to 38, wherein the reconstituted carbon-based material comprises an aerosol former. Example 40. 40. The aerosol-forming substrate of example 39, wherein the reconstituted carbon-based material comprises 7-60% by weight of the aerosol former on a dry weight basis. Example 41. 41. The aerosol-forming substrate according to any one of examples 33 to 40, wherein the reconstituted carbon-based material comprises fibers. Example 42. 42. The aerosol-forming substrate of example 41, wherein the layer of reconstituted carbon-based material comprises between 2 and 20% by weight, on a dry weight basis, of fibers. Optionally, the fibers are cellulose fibers. Example 43. 43. The aerosol-forming substrate of any one of examples 33 to 42, wherein the reconstituted carbon-based material comprises a binder. Example 44. 44. The aerosol-forming substrate of example 43, wherein the reconstituted carbon-based material comprises 2-10% by weight of binder on a dry weight basis. Example 45. The aerosol-forming substrate according to any one of examples 33 to 44, wherein the layer of the carbon-based thermally conductive material does not contain tobacco. Example 46. The aerosol-forming substrate of example 45, wherein the layer of carbon-based thermally conductive material can be free of nicotine. Example 47. The aerosol-forming substrate according to any one of Examples 33 to 46, wherein the layer of the carbon-based thermally conductive material may be formed by a casting process. Example 48. An aerosol-forming substrate according to any one of Examples 1 to 47, wherein the co-laminate sheet comprises an assembly of sheets or has the form of an assembly of sheets. Example 49. 49. The aerosol-forming substrate according to any one of Examples 1 to 48, wherein the layer of carbon-based thermally conductive material has a thermal conductivity of greater than 2, 5, 10, 20, 50, 100, 200, 500, 1000, or 1500 W / (mK). Example 50. 50. The aerosol-forming substrate of any one of Examples 1 to 49, wherein the layer of carbon-based thermally conductive material lies in or defines a plane, and the thermal conductivity of the layer of carbon-based thermally conductive material in the plane is greater than 2, 5, 10, 20, 50, 100, 200, 500, 1000, or 1500 W / mK. Example 51. 51. The aerosol-forming substrate according to any one of the preceding embodiments, wherein the layer of carbon-based thermally conductive material comprises more than 10, 30, 50, 70, 80, 90, 95, 98, 99, 99.5, or 99.9% by weight of carbon. Example 52. 52. The aerosol-forming substrate of any one of the preceding embodiments, wherein the layer of carbon-based thermally conductive material constitutes no more than 90, 80, 50, 20, 10, or 5 percent by weight of the aerosol-forming substrate. Example 53. 53. The aerosol-forming substrate of any one of examples 1 to 52, wherein the layer of carbon-based thermally conductive material constitutes 0.1, 0.2, 0.5, 1, 2, 3, 5, 10, 20, 30, 40, or 50 weight percent or more of the aerosol-forming substrate. Example 54. 54. The aerosol-forming substrate according to any one of Examples 1 to 53, wherein the layer of the carbon-based thermally conductive material constitutes 20 to 90, 20 to 90, 30 to 90, 40 to 90, 20 to 80, 30 to 80, 40 to 80, 20 to 70, 30 to 70, 40 to 70, 20 to 60, 30 to 60, 40 to 60, 20 to 50, 30 to 50 percent by weight of the aerosol-forming substrate. Example 55. A rod for aerosol-generating articles, comprising an assembly of sheets of aerosol-forming substrates as defined in any one of Examples 1 to 54, and a wrapper surrounding the assembly of sheets of aerosol-forming substrates. Example 56. The rod of example 55, further comprising a susceptor element located within the rod of the aerosol-forming substrate. Example 57. The rod of Example 56, wherein the susceptor element is an elongated susceptor element. Example 58. 58. The rod of embodiment 56 or 57, wherein the susceptor element extends longitudinally within the rod of the aerosol-forming substrate. Example 59. The rod of any one of Examples 56 to 58, wherein the rod is substantially cylindrical. Example 60. The rod of Example 59, wherein the susceptor element is positioned at a radially central position within the rod of the aerosol-forming substrate and extends along the central longitudinal axis of the rod of the aerosol-forming substrate. Example 61. The rod of any one of Examples 56-60, wherein the susceptor element is in the form of a pin, rod, strip, or blade. Example 62. The rod of any one of Examples 56-61, wherein the susceptor element has a length of 5 to 15, 6 to 12, or 8 to 10 millimeters. Example 63. 63. The rod of embodiment 62, wherein the layer of carbon-based thermally conductive material comprises a susceptor material. Example 64. The rod of Example 63, wherein there is no susceptor element present within the aerosol-forming substrate or within the rod of the aerosol-forming substrate, except for the layer of thermally conductive material. Example 65. 65. An aerosol-generating article for use in an electrical aerosol generating device, the article comprising an aerosol-forming substrate as defined in any one of Examples 1 to 64. Example 66. 66. The aerosol-generating article of example 65, comprising a plurality of elements assembled within a wrapper or casing in the form of a rod. Example 67. 66. The aerosol-generating article of example 65, wherein the plurality of elements comprises an upstream element, an aerosol-forming substrate, a support element, an aerosol cooling element, and a mouthpiece element. Example 68. An aerosol generating system comprising an aerosol generating article as defined in any one of Examples 65 to 67 and an electrical aerosol generating device, wherein the aerosol generating device is engageable with and disengageable from the aerosol generating article. Example 69. 69. The aerosol generating system of Example 68, wherein the aerosol generating device is configured to resistively heat the aerosol generating article. Example 70. An aerosol generation system as described in Example 69, wherein the device is equipped with a resistive heating element. Example 71. An aerosol generation system as described in Example 70, wherein the heating element comprises an electrical resistive track. Example 72. 72. The aerosol generating system of embodiment 71, wherein the aerosol generating device is configured to inductively heat the aerosol generating article. Example 73. An aerosol generation system as described in Example 72, wherein the device comprises an inductor, such as an inductor coil. Example 74. An aerosol generation system as described in Example 73, wherein the device is configured to generate a fluctuating electromagnetic field. Example 75. A method of forming an aerosol-forming substrate, the method comprising combining a layer of an aerosol-forming material with a layer of a carbon-based thermally conductive material to form a co-laminate sheet. Example 76. The method of example 75, wherein the layer of aerosol-forming material is a continuous sheet of aerosol-forming material. Example 77. 77. The method of example 75 or 76, wherein the layer of carbon-based thermally conductive material is a continuous sheet of carbon-based thermally conductive material. Example 78. The method of any one of Examples 75-77, wherein the method comprises forming a continuous co-laminate sheet. Example 79. The method of any one of Examples 75-78, further comprising assembling the co-laminate sheets transversely to their longitudinal axes. Example 80. The method of any one of Examples 75-79, wherein the method further comprises encasing the collection of co-laminate sheets in a wrapper to form a rod. Example 81. The method of example 80, wherein the method includes forming a continuous co-laminate sheet such that an assembly of the wrapper-wrapped sheets forms a continuous rod. Example 82. The method of example 81, further comprising cutting the continuous rod into a plurality of individual rods. Example 83. The method of any one of examples 75-82, wherein the combining of the layers comprises contacting, preferably in intimate contact with, the layer of carbon-based thermally conductive material and the layer of aerosol-forming material with one another. Example 84. 84. The method of example 83, further comprising crimping the carbon-based thermally conductive layer and the aerosol-forming material layer while the layers are in contact with one another. Example 85. The method of example 84, wherein the crimping step comprises feeding the carbon-based thermally conductive layer and the aerosol-forming material layer through crimping rollers to form a continuous crimped co-laminate sheet. Example 86. The method of example 84, wherein the crimped co-laminate sheet has a plurality of spaced ridges or corrugations substantially parallel to the longitudinal axis of the sheet. Example 87. 87. The method of any one of Examples 75-86, wherein the combining of the sheets comprises overlaying a sheet of the aerosol-forming material onto a sheet of the carbon-based thermally conductive material. Example 88. The method of any one of examples 75-87, wherein combining the layers comprises layering a sheet of carbon-based thermally conductive material over the sheet of aerosol-forming material. Example 89. The method of any one of Examples 75 to 88, further comprising forming a layer of aerosol forming material. Example 90. The method of example 89, wherein the step of forming a layer of aerosol-forming material comprises a step of a papermaking process, or preferably a casting process. Example 91. 91. The method of example 90, wherein the step of forming a layer of aerosol-forming material comprises casting a slurry comprising the organic material. Example 92. The method of example 91, wherein the step of forming a sheet further comprises drying the slurry to form an aerosol-forming material. Example 93. The method of any one of Examples 91-93, wherein the step of combining the sheets comprises overlaying a sheet of the aerosol-forming material onto a sheet of the carbon-based thermally conductive material, and the step of forming a layer of the aerosol-forming material is performed prior to the step of combining the layers. Example 94. The method of any one of Examples 91-93, wherein the step of forming the layer of aerosol-forming material can be performed simultaneously with the step of combining the layers. Example 95. 95. The method of example 94, wherein a sheet of aerosol-forming material is formed on a sheet of carbon-based thermally conductive material. Example 96. 96. The method of example 95, wherein the step of forming a sheet of aerosol-forming material comprises casting a slurry of the aerosol-forming material onto, preferably directly onto, the layer of carbon-based thermally conductive material. Example 97. 97. The method of example 96, further comprising drying the slurry onto the layer of carbon-based thermally conductive material. Example 98. The method of any one of Examples 75-97, further comprising forming a layer of a carbon-based thermally conductive material. Example 99. 99. The method of example 98, wherein the step of forming a layer of carbon-based thermally conductive material comprises preparing, forming, or manufacturing a reconstituted carbon-based material. Example 100. 100. The method of example 99, wherein the step of producing a reconstituted carbon-based material comprises forming a slurry including thermally conductive particles. Example 101. The method of example 100, wherein the step of producing a reconstituted carbon-based material further comprises casting and drying the slurry to form a reconstituted carbon-based material. Example 102. The method of example 99 or 100, wherein the slurry comprises fibers. Example 103. The method of any one of embodiments 99-102, wherein the slurry comprises a binder. Example 104. The method of any one of examples 99-103, wherein forming the slurry further comprises forming a first mixture. Example 105. The method of example 104, wherein the first mixture comprises fibers. Example 106. The method of example 104 or 105, wherein forming the slurry includes forming a second mixture. Example 107. The method of example 106, wherein the second mixture comprises thermally conductive particles. Example 108. 1. A method of forming a rod comprising an aerosol-forming substrate, the method comprising: providing a co-laminate sheet comprising a layer of an aerosol-forming material and a layer of a carbon-based thermally conductive material; Assembling the co-laminate sheets transversely to their longitudinal axes; and wrapping the collection of co-laminate sheets in a wrapper to form a continuous rod. Example 109. The method according to example 108, wherein the method comprises any of the steps of the method according to any one of examples 75 to 108. Example 110. A method of forming an aerosol-generating article comprising the method steps of Example 108 or 109.

[0224] Specific embodiments will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0225] [Figure 1] FIG. 1 shows a schematic cross-sectional view of a first embodiment of an aerosol-generating article. [Diagram 2] FIG. 2 shows a schematic cross-section of a first apparatus for forming a rod according to an illustrative embodiment. [Diagram 3] FIG. 3 shows a schematic cross-section of a first apparatus for forming rods according to an illustrative embodiment. [Figure 4] FIG. 4 shows a schematic cross-sectional view of a first embodiment of an aerosol generation system. [Diagram 5] FIG. 5 shows a schematic cross-sectional view of a second embodiment of an aerosol generation system. [Figure 6] FIG. 6 shows a schematic cross-sectional view of a second embodiment of an aerosol-generating article. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0226] 1 shows a schematic cross-sectional view of a first embodiment of an aerosol-generating article 10. The aerosol-generating article 10 comprises a rod of aerosol-forming substrate 12 and a downstream section 14 located downstream of the rod of aerosol-forming substrate 12. Additionally, the aerosol-generating article 10 comprises an upstream section 16 located upstream of the rod of aerosol-forming substrate 12. Thus, the aerosol-generating article 10 extends from an upstream or distal end 18 to a downstream or proximal or oral end 20.

[0227] The aerosol-generating article has a total length of about 45 millimeters.

[0228] The downstream section 14 comprises a support element 22 located immediately downstream of the rod 12 of the aerosol-forming substrate, the support element 22 being in longitudinal alignment with the rod 12. In the embodiment of Figure 1, the upstream end of the support element 22 abuts the downstream end of the rod 12 of the aerosol-generating substrate. In addition, the downstream section 14 comprises an aerosol cooling element 24 located immediately downstream of the support element 22, the aerosol cooling element 24 being in longitudinal alignment with the rod 12 and the support element 22. In the embodiment of Figure 1, the upstream end of the aerosol cooling element 24 abuts the downstream end of the support element 22.

[0229] As will become apparent from the following description, the support element 22 and the aerosol cooling element 24 together define an intermediate hollow section 50 of the aerosol-generating article 10. Taken as a whole, the intermediate hollow section 50 does not contribute substantially to the overall RTD of the aerosol-generating article. The RTD of the intermediate hollow section 26 as a whole is substantially 0 millimeters HO.

[0230] The support element 22 may include a first hollow tubular segment 26. The first hollow tubular segment 26 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The first hollow tubular segment 26 defines an interior cavity 28 extending entirely from an upstream end 30 of the first hollow tubular segment to a downstream end 32 of the first hollow tubular segment 20. The interior cavity 28 is substantially empty, thereby allowing substantially unrestricted airflow therealong. The first hollow tubular segment 26, and consequently the support element 22, does not substantially contribute to the overall RTD of the aerosol-generating article 10. More specifically, the RTD of the first hollow tubular segment 26 (which is substantially the RTD of the support element 22) is substantially 0 millimeters H2O.

[0231] The first hollow tubular segment 26 has a length of about 8 millimeters, an outer diameter of about 7.25 millimeters, and an inner diameter (D FTS ), the peripheral wall thickness of the first hollow tubular segment 26 is therefore approximately 2.67 millimeters.

[0232] The aerosol cooling element 24 comprises a second hollow tubular segment 34. The second hollow tubular segment 34 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The second hollow tubular segment 34 defines an interior cavity 36 extending from an upstream end 38 of the second hollow tubular segment all the way to a downstream end 40 of the second hollow tubular segment 34. The interior cavity 36 is substantially empty, thereby allowing substantially unrestricted airflow along the interior cavity 36. The second hollow tubular segment 28, and consequently the aerosol cooling element 24, does not substantially contribute to the overall RTD of the aerosol-generating article 10. More specifically, the RTD of the second hollow tubular segment 34 (which is essentially the RTD of the aerosol cooling element 24) is substantially 0 millimeters H2O.

[0233] The second hollow tubular segment 34 has a length of about 8 millimeters, an outer diameter of about 7.25 millimeters, and an inner diameter (D STS) of the peripheral wall of the second hollow tubular segment 34 is approximately 2 millimeters. FTS ) and the inner diameter (D STS ) is about 0.75.

[0234] The aerosol-generating article 10 includes a ventilation zone 60 provided at a location along the second hollow tubular segment 34. More specifically, the ventilation zone is provided approximately 2 millimeters from the upstream end of the second hollow tubular segment 34. In this embodiment, the ventilation zone 60 comprises a circumferential row of perforations through the paper wrapper 70, and the ventilation level of the aerosol-generating article 10 is approximately 25 percent.

[0235] 1, the downstream section 14 further comprises a mouthpiece element 42 located downstream of the intermediate hollow section 50. More specifically, the mouthpiece element 42 is positioned immediately downstream of the aerosol cooling element 24. As shown in the drawing of FIG.

[0236] Mouthpiece element 42 is provided in the form of a cylindrical plug of low density cellulose acetate.

[0237] Mouthpiece element 42 has a length of about 12 millimeters and an outer diameter of about 7.25 millimeters. The RTD of mouthpiece element 42 is about 12 millimeters H2O. The ratio of the length of mouthpiece element 42 to the length of intermediate hollow section 50 is about 0.6.

[0238] The rod 12 of the aerosol-forming substrate has an outer diameter of about 7.25 millimeters, and a length of about 12 millimeters.

[0239] The upstream section 16 comprises an upstream element 46 located immediately upstream of the rod 12 of the aerosol-forming substrate, the upstream element 46 being longitudinally aligned with the rod 12. In the embodiment of FIG. 1, the downstream end of the upstream element 46 abuts the upstream end of the rod 12 of the aerosol-forming substrate. The upstream element 46 is provided in the form of a cylindrical plug of cellulose acetate. The upstream element 46 has a length of about 5 millimeters. The RTD of the upstream element 46 is about 30 millimeters HO.

[0240] The upstream element 46 , the rod of aerosol-forming substrate 12 , the support element 22 , the aerosol cooling element 24 , and the mouthpiece element 42 are enclosed by a paper wrapper 70 .

[0241] The rod of aerosol-forming substrate 12 comprises an assembly of co-laminate sheets including a layer of aerosol-forming material 13 and a layer of carbon-based thermally conductive material 15. The layer of aerosol-forming material 13 is in intimate contact with the layer of carbon-based thermally conductive material, stacked one on top of the other. As explained below, the sheets are assembled to form a plurality of substantially parallel ridges or corrugations. Thus, the cross-section of the sheet shown in FIG. 1 appears to have multiple layers of aerosol-forming material 13 sandwiched between layers of carbon-based thermally conductive material 15 resulting from the corrugated co-laminate structure of the rod of aerosol-forming substrate 12.

[0242] The aerosol-forming material 13 includes a reconstituted sheet that includes tobacco material and glycerin.

[0243] The layer of carbon-based thermally conductive material 15 is a foil made of graphite, expanded graphite, or both graphite and expanded graphite.

[0244] The cardboard tube 34 has a length of 16 mm and provides free space within the article 10 in which the volatile components generated by heating the aerosol-forming substrate can cool to form an aerosol.

[0245] The mouthpiece element 42 is provided in the form of a cylindrical plug of low density cellulose acetate. The mouthpiece element 42 has a length of about 12 millimeters and an outside diameter of about 7.25 mm. The RTD of the mouthpiece element 42 is about 12 millimeters H2O.

[0246] It is clear that the configuration of the aerosol-generating article 10 in Figure 1 is intended to serve as an example only: the thermally enhanced aerosol-forming substrate may be used, for example, in aerosol-generating articles that are longer, e.g., 80 mm long, and thinner, e.g., 4.5 mm in diameter.

[0247] 2 shows an apparatus for forming a rod 12 of an aerosol-forming substrate. The apparatus generally includes a feed means for supplying a continuous co-laminate sheet of homogenized tobacco and aluminum foil, a crimping means for crimping the continuous co-laminate sheet, a rod-forming means for assembling the crimped continuous co-laminate sheet and enclosing the assembled material in a wrapper to form a continuous rod, and a cutting means for cutting the continuous rod into a plurality of individual rods. The apparatus also includes a conveying means for conveying the continuous co-laminate sheet material from the feed means to the rod-forming means, through the crimping means, and downstream through the apparatus.

[0248] As shown in Figure 2, the feeding means for providing the continuous co-laminated sheet comprises a continuous co-laminated sheet including a layer of aerosol-forming material and a layer of thermally conductive material, the continuous co-laminate sheet being mounted on a bobbin 4. The crimping means includes a pair of rotatable crimping rollers 6. In use, the continuous co-laminate sheet 2 is drawn from a first bobbin 4 and conveyed downstream by a conveying means through a series of guides and tension rollers to the pair of crimping rollers 6. As the continuous co-laminate sheet 2 is fed between the pair of crimping rollers 6, the crimping rollers engage and crimp the sheet 2 to form a crimped continuous co-laminate sheet 8 having a plurality of spaced ridges or corrugations substantially parallel to the longitudinal axis of the sheet through the apparatus.

[0249] The continuously crimped sheet 8 is conveyed downstream from the pair of crimping rollers 6 to a rod forming means where it is fed through a tapered funnel or horn 31. The tapered funnel 31 collects the continuously crimped co-laminate sheet 8 transversely to its longitudinal axis. The sheet of material 8 assumes a substantially cylindrical structure as it passes through the tapered funnel 31.

[0250] Upon exiting the tapered funnel 31, the collection of co-laminate sheets is wrapped into a continuous sheet of wrapping material 37. The continuous sheet of wrapping material is provided from a bobbin 35 and wrapped by an endless belt conveyor or tool about the collection of continuously crimped sheets of homogenized tobacco material. As shown in Figure 1, the rod forming means includes an adhesive application means 17 for applying adhesive to one of the longitudinal edges of the continuous sheet of wrapping material such that the opposing longitudinal edges of the continuous sheet of wrapping material contact and adhere to one another to form a continuous rod.

[0251] The rod forming means further comprises drying means 19 downstream of the adhesive application means 17 which, in use, dries the adhesive applied to the joints of the continuous rod as the continuous rod is conveyed downstream from the rod forming means to the cutting means.

[0252] The cutting means includes a rotary cutter 21 which cuts the continuous rod into a plurality of individual rods of unit rod length or multiple unit rod lengths.

[0253] Figure 3 shows an alternative apparatus for forming a rod 12 of an aerosol-forming substrate. The apparatus of Figure 3 is similar to that of Figure 2 and like features are numbered accordingly. The difference between the apparatus of Figures 2 and 3 is that the apparatus of Figure 3 includes separate bobbins 35 for the continuous sheet of aerosol-forming material and the continuous sheet of thermally conductive material, rather than a single bobbin containing a co-laminate sheet of aerosol-forming substrate.

[0254] In the apparatus of FIG. 3, a continuous sheet of aerosol-forming material is mounted on a primary bobbin 23 and a continuous sheet of carbon-based thermally conductive material is mounted on a secondary bobbin 33. In use, the continuous sheet of aerosol-forming material is drawn from the first bobbin 23 and conveyed downstream by a conveying mechanism through a series of guides and tension rollers to a pair of crimping rollers 6. A continuous sheet of carbon-based thermally conductive material is similarly drawn from the secondary bobbin 33 and conveyed downstream by a conveying mechanism to a pair of crimping rollers 6. Before passing through the crimping rollers 6, the continuous sheet of carbon-based thermally conductive material is brought into intimate contact with the aerosol-forming material such that the carbon-based thermally conductive material is above the aerosol-forming material. This forms a continuous co-laminate sheet including a layer of carbon-based thermally conductive material and a layer of aerosol-forming material that passes through the crimping rollers 6. The continuous co-laminate sheet then passes through the apparatus of FIG. 3 in the same manner as described in connection with FIG. 2.

[0255] In other embodiments, the bobbin of aerosol-forming material may be replaced with a bobbin of carbon-based thermally conductive material such that the aerosol-forming material is on top of the carbon-based thermally conductive material before passing through the crimping rollers.

[0256] In one embodiment, the aerosol-forming material described above is formed by a casting process comprising the following steps: premixing the shredded tobacco material, a binder, and guar gum with an aerosol former, and glycerin to form a premix; mixing the premix with water to form a slurry; homogenizing the slurry using a high shear mixer; casting the slurry onto a conveyor belt; Controlling the thickness of the slurry and drying the slurry to form large sheets of aerosol-forming material.

[0257] The above process may be used to produce a continuous sheet of aerosol-forming material for the bobbin 23 of the apparatus of FIG.

[0258] In another embodiment, the aerosol-forming material described above is formed by a casting process comprising the steps of: premixing the shredded tobacco material, a binder, and guar gum with an aerosol former, and glycerin to form a premix; mixing the premix with water to form a slurry; homogenizing the slurry using a high shear mixer; casting the slurry onto a continuous sheet of carbon-based thermally conductive material; Controlling the thickness of the slurry and drying the slurry to form large sheets of aerosol-forming material.

[0259] The above process may be used to produce a continuous co-laminate sheet including a layer of aerosol-forming material. The above process may be used to produce a continuous sheet of aerosol-forming material for the bobbin 4 of the apparatus of FIG.

[0260] In one embodiment, the carbon-based thermally conductive material is a commercially available foil or film.

[0261] Suitable carbon-based thermally conductive materials are available from NeoGraf solutions LLC, 11709 Madison Avenue, Lakewood, Ohio, United States 44107. In particular, the eGraf SpreaderShield™ range of heat spreaders are suitable carbon-based thermally conductive materials. NeoGraf solutions provide low density heat spreaders in film or foil form, with in-plane conductivity of 300-1600 W / (mK), thickness of 17 micrometers, and tensile strength of over 7 megapascals.

[0262] Another example of a suitable carbon based thermally conductive material is Panasonic Industry's range of EYGS182307 PGS graphite sheets available from RS Components (https: / / uk.rs-online.com / web / ).

[0263] In another embodiment, the carbon-based thermally conductive material is a reconstituted carbon-based material.

[0264] In one embodiment, the method includes forming a reconstituted carbon-based material. The slurry is formed using a lab disperser that has the ability to mix viscous liquids, disperse powders through liquids, and remove gases from the mixture (e.g., by applying a vacuum or other suitable low pressure). In this embodiment, a lab disperser commercially available from PC Laborsystem was used.

[0265] To form the slurry, a first mixture is formed by adding about 7.11 grams of aerosol former, then about 157.5 grams of water, then about 1.57 grams of fiber to a lap disperser. These first components are then mixed at 600-700 rpm for 5 minutes at 25 degrees Celsius to ensure a homogenous mixture and to hydrate the fiber. A second mixture is then formed by manually mixing about 32.95 grams of thermally conductive particles and about 0.92 grams of binder. This mixing of the second mixture avoids the formation of lumps in the lab dispersion. The second mixture is then added to the first mixture to form a combined mixture. The combined mixture is then mixed at 5000 rpm for 4 minutes under a first reduced pressure of 25 degrees Celsius and about 200 mbar. The reduced pressure can help ensure that the thermally conductive particles are uniformly dispersed in the mixture and that there is little air trapped in the combined mixture and little clumping. The combined mixture is then mixed at 5000 rpm for 20 seconds under a second vacuum of 25 degrees Celsius and about 100 mbar, which may help remove any remaining air bubbles, to form a slurry for casting.

[0266] The slurry is then cast and dried using a suitable apparatus, in this embodiment a commercially available Labcoater Mathis apparatus is used, which includes a stainless steel, flat support, and a comb blade to control the thickness of the slurry cast onto the flat support.

[0267] The slurry is cast onto a flat support and the gap between the comb blade and the flat support is set at 0.6 millimeters, ensuring that at any point the thickness of the slurry is no more than 0.6 millimeters.

[0268] The slurry is then dried with hot air at 120-140 degrees Celsius for 2-5 minutes. After this drying, a sheet of aerosol-forming substrate is formed. The sheet has a thickness of about 159 microns, a basis weight of about 125.7 grams per square meter, and a density of about 0.79 kilograms per cubic meter.

[0269] 4 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 the aerosol-generating article 10 of FIG.

[0270] The aerosol generating device 102 comprises a battery 104, a controller 106, a heating blade 108 coupled to the battery, and a puff detection mechanism (not shown). The controller 106 is coupled to the battery 104, the heating blade 108, and the puff detection mechanism.

[0271] The aerosol generating device 102 further comprises a housing 110 defining a substantially cylindrical cavity for receiving a portion of the article 10. The heating blade 108 is centrally located within the cavity and extends longitudinally from a base of the cavity.

[0272] In this embodiment, the heating blade 108 comprises a substrate and an electrically resistive track located on the substrate. The battery 104 is coupled to the heating blade 108 such that a current can be applied to the electrically resistive track to heat the electrically resistive track and the heating blade 108 to an operating temperature.

[0273] In use, the user inserts the article 10 into the cavity and causes the heating blade 108 to penetrate the upstream element 46 and rod 12 of the aerosol-forming substrate of the article 10. Figure 4 shows the article 10 inserted into the cavity of the device 102.

[0274] The user then draws on the downstream end of the article 10. This causes air to flow through an 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.

[0275] When a user puffs on the article 10, air flows through the air inlet of the device. The puff detection mechanism detects when the airflow rate through the air inlet increases above a non-zero threshold flow rate. The puff detection mechanism sends a signal to the controller 106 in response. The controller 106 then controls the battery 104 to apply current to the electrical resistive track, heating the heating blade 108. This heats the rod of aerosol-forming substrate 12 in contact with the heating blade 108.

[0276] The layer of thermally conductive material has a significantly higher thermal conductivity than the surrounding aerosol-forming material. In this way, the layer of thermally conductive material can conduct thermal energy throughout the bulk of the aerosol-forming material. This allows a large portion of the aerosol-forming substrate to reach a temperature high enough to release volatile compounds, thus allowing for more efficient use of the aerosol-forming substrate.

[0277] Upon heating the aerosol-forming substrate, the aerosol-forming substrate releases volatile compounds. These compounds are entrained by air flowing from the upstream end 18 of the article 10 toward the downstream end 20 of the article 10. The compounds cool and condense as they pass through the interior cavities 28, 36 of the support element 22 and the aerosol cooling element 24 to form an aerosol. The aerosol then passes through the mouthpiece element 42, which filters out unwanted particles entrained in the airflow, and may then pass into the user's mouth.

[0278] When the user stops inhaling on the article 10, the airflow rate through the air inlet of the device decreases below a non-zero threshold flow rate. This is detected by the puff detection mechanism, which in response sends a signal to the controller 106. The controller 106 then controls the battery 104 to reduce the current through the electrical resistive track to zero.

[0279] After taking several puffs from the article 10, the user may choose to replace the article 10 with a new article.

[0280] 5 shows a schematic cross-sectional view of a second embodiment of an aerosol-generating system 200. System 200 comprises an aerosol-generating device 202 and the aerosol-generating article 11 of FIG.

[0281] The aerosol generating device 202 includes a battery 204, a controller 206, an inductor coil 208, and a puff detection mechanism (not shown). The controller 206 is coupled to the battery 204, the inductor coil 208, and the puff detection mechanism.

[0282] The aerosol generating device 202 further comprises a housing 210 defining a substantially cylindrical cavity for receiving a portion of the article 11. An inductor coil 208 spirally rotates around the cavity.

[0283] The battery 204 is coupled to the inductor coil 208 such that an alternating current can be passed through the inductor coil 208 .

[0284] In use, a user inserts an item 11 into the cavity. Figure 5 shows an item 11 inserted into the cavity of the device 202.

[0285] The user then draws on the downstream end of article 11. This causes air to flow through an air inlet (not shown) of device 202, then through article 11, from upstream end 18 to downstream end 20, and into the user's mouth.

[0286] When a user puffs on the article 11, air flows through the air inlet of the device. The puff detection mechanism detects that the airflow rate through the air inlet has increased above a non-zero threshold flow rate. The puff detection mechanism sends a signal to the controller 206 accordingly. The controller 206 then controls the battery 204 to pass an alternating current through the inductor coil 208, which in turn generates a varying electromagnetic field. The rod 13 of the combined aerosol-forming substrate is located within this varying electromagnetic field. The thermally conductive material 15, the graphite and expanded graphite materials, are susceptor materials. Thus, the varying electromagnetic field induces eddy currents in the thermally conductive material 15 (which is also electrically conductive). This causes the thermally conductive material 15 to heat, which in turn heats the nearby aerosol-forming material.

[0287] Heating the aerosol-forming material causes the aerosol-forming material to release volatile compounds. These compounds are entrained by air flowing from the upstream end 18 of the article 11 toward the downstream end 20 of the article 11. The compounds cool and condense as they pass through the internal cavities 28, 36 of the support element and the aerosol cooling element to form an aerosol. The aerosol then passes through the mouthpiece element 42, which filters out unwanted particles entrained in the airflow, and may then pass into the user's mouth.

[0288] When the user stops inhaling on the article 11, the airflow rate through the air inlet of the device decreases below a non-zero threshold flow rate. This is detected by the puff detection mechanism, which in response sends a signal to the controller 206. The controller 206 then controls the battery 204 to reduce the current through the electrical resistive track to zero.

[0289] After taking several puffs from article 11, the user may choose to replace article 11 with a new article.

[0290] Figure 6 shows a schematic cross-sectional view of a second embodiment of an aerosol-generating article 510. This second embodiment is identical to the first embodiment of Figure 1, except that the rod of aerosol-forming substrate 12 is replaced by an alternative rod of aerosol-forming substrate 512. The same reference numbers are used for the same components in the embodiments of Figures 1 and 6.

[0291] The rod 512 of the aerosol-forming substrate of the second embodiment in FIG. 6 is identical to the rod 12 of the aerosol-forming substrate of the first embodiment in FIG. 1, except that the rod 512 of the aerosol-forming substrate of the second embodiment in FIG. 6 additionally includes an elongated susceptor element 580.

[0292] The susceptor element 580 is disposed substantially longitudinally within the aerosol-forming substrate rod 512 such that the susceptor element 580 is substantially parallel to the longitudinal direction of the aerosol-forming substrate rod 512. As shown in the drawing of Figure 6, the susceptor element 580 is located at a radially central position within the rod and extends along the longitudinal axis of the rod 12.

[0293] The susceptor element 580 extends all the way from the upstream end to the downstream end of the aerosol-forming substrate rod 512. Thus, the susceptor element 580 has substantially the same length as the aerosol-forming substrate rod 512.

[0294] In the embodiment of FIG. 6, the susceptor element 580 is provided in the form of a strip of ferromagnetic steel and has a length of about 12 millimeters, a thickness of about 60 micrometers, and a width of about 4 millimeters.

[0295] The aerosol-generating article 510 of Figure 6 may be used with the aerosol-generating apparatus 202 of Figure 4 in the same manner as the aerosol-generating article 11 of Figure 2. Notably, the inclusion of the susceptor element 580 means that the article 510 may be inductively heated regardless of whether the thermally conductive material includes a suitable susceptor material for inductive heating.

[0296] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like should be understood in all cases as being modified by the term "about." Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± 10% of A. Within this context, the number A may be considered to include numerical values ​​that are within the general standard error for the measurement of the property that the number A modifies. The number A may, in some instances used in the appended claims, deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel properties of the claimed invention. Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. An aerosol-forming substrate for use in a heated aerosol-generating article, comprising a co-laminated sheet comprising a layer of an aerosol-forming material and a layer of a carbonaceous heat-conductive material different from the aerosol-forming material, wherein the layer of the carbonaceous heat-conductive material comprises a reconstituted carbonaceous material, and the reconstituted carbonaceous material comprises an aerosol-forming matrix and heat-conductive particles, each of the heat-conductive particles having a thermal conductivity of at least 1 watt per meter kelvin in at least one direction at 25 degrees Celsius, the aerosol-forming substrate.

2. The aerosol-forming substrate according to claim 1, wherein the layer of the carbonaceous heat-conductive material is in the form of a film or a foil.

3. The aerosol-forming substrate according to claim 1, wherein the layer of the carbonaceous heat-conductive material comprises carbon fibers, graphite, or graphene.

4. The aerosol-forming substrate according to claim 1, wherein the reconstituted carbonaceous material comprises 7 to 60% by weight of the aerosol-forming matrix on a dry basis.

5. The aerosol-forming substrate according to claim 1, wherein the co-laminated sheet comprises an assembly of sheets or is in the form of an assembly of sheets.

6. The aerosol-forming substrate according to claim 1, wherein all or part of the heat-conductive particles comprise one or more of graphite, expanded graphite, graphene, carbon nanotubes, and charcoal.

7. The aerosol-forming substrate according to claim 1, wherein the reconstituted carbonaceous material comprises one or both of a fiber and a binder.

8. A rod for an aerosol-generating article, the rod comprising the aerosol-forming substrate according to claim 1.

9. A heated aerosol-generating article comprising the rod according to claim 8.

10. An aerosol-generating system comprising the aerosol-generating article according to claim 9 and an electrically operated aerosol-generating device.

11. A method of forming an aerosol-forming substrate, comprising combining a layer of an aerosol-forming material with a layer of a carbonaceous heat-conductive material different from the aerosol-forming material to form a co-laminated sheet, wherein the layer of the carbonaceous heat-conductive material comprises a reconstituted carbonaceous material, and the reconstituted carbonaceous material comprises an aerosol-forming matrix and heat-conductive particles, each of the heat-conductive particles having a thermal conductivity of at least 1 watt per meter kelvin in at least one direction at 25 degrees Celsius, the method.

12. The method for forming an aerosol-forming substrate according to claim 11, further comprising the step of forming a layer of the aerosol-forming material.

13. The method for forming an aerosol-forming substrate according to claim 12, wherein the step of combining the sheets comprises casting a layer of the aerosol-forming material onto the layer of the carbonaceous heat-conductive material.

14. A method for forming a rod comprising an aerosol-forming substrate, the method comprising: providing a co-laminated sheet comprising an aerosol-forming material and a carbonaceous heat-conductive material different from the aerosol-forming material, wherein the layer of the carbonaceous heat-conductive material comprises a reconstituted carbonaceous material, the reconstituted carbonaceous material comprises an aerosol-forming body and heat-conductive particles, and each of the heat-conductive particles has a thermal conductivity of at least 1 watt per meter kelvin in at least one direction at 25 degrees Celsius; collecting the co-laminated sheet transversely with respect to its longitudinal axis; wrapping the collection of the co-laminated sheets with a wrapper to form a continuous rod; and cutting the continuous rod into a plurality of individual rods.

15. A method for forming an aerosol-generating article, comprising assembling the aerosol-generating article from a plurality of components, wherein the plurality of components comprise the aerosol-forming substrate according to claim 1.

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