Aerosol-forming substrate with improved thermal conductivity - Patents.com

Abstract

An aerosol-forming substrate for use in a heated aerosol-generating article (10) is provided, the aerosol-forming substrate comprising an aerosol-forming material and greater than 0.1 weight percent carbon particles (44), the carbon particles having a volume average particle size greater than 10 micrometers.

Description

[Technical field]

[0001] The present disclosure relates to an aerosol-forming substrate, in particular an aerosol-forming substrate having improved thermal conductivity. The present disclosure also relates to a method for forming an aerosol-forming substrate, in particular a method for making an aerosol-forming substrate having improved thermal conductivity. The present disclosure also relates to an article comprising said substrate, and a system comprising said article. BACKGROUND OF THEINVENTION

[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 and cause the aerosol-forming substrate to release volatile compounds. These compounds then cool to form an aerosol, which is inhaled by the user.

[0003] Known aerosol-forming substrates typically have a relatively low thermal conductivity. This may be particularly undesirable in aerosol generating systems where a blade is inserted into the aerosol-forming substrate to heat it. This is because the low thermal conductivity of the aerosol-forming substrate may lead to a relatively large temperature gradient in 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 a high temperature and therefore does not release as many volatile compounds as it would 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 low efficiency of use of the aerosol-forming substrate.

[0004] In addition, known aerosol-forming substrates are typically not inductively heatable to operating temperatures. This means that for induction heating, a separate susceptor element is typically required. This can lead to the same problems as discussed above. For example, if an induction heating susceptor element is placed in a central location within the substrate, the part of the aerosol-forming substrate that is located furthest from the susceptor element may not reach a high temperature and therefore may not have many volatile compounds.

[0005] Attempts have been made to increase the thermal conductivity of aerosol-forming substrates, but so far these attempts have been inadequate in one or more respects. Summary of the Invention

[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.

[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 an aerosol-forming material. The aerosol-forming substrate may include particles, such as thermally conductive particles. The aerosol-forming substrate may include more than 0.1 weight percent of thermally conductive particles. The thermally conductive particles may be carbon particles.

[0008] Therefore, there is provided an aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising an aerosol-forming material and thermally conductive particles.

[0009] Also provided is an aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising an aerosol-forming material and greater than 0.1 weight percent carbon particles, the carbon particles having a volume average particle size greater than 10 micrometers.

[0010] Also provided is an aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising an aerosol-forming material and more than 0.1 weight percent carbon particles, the carbon particles having a particle size distribution having a D90 particle size and a D10 particle size, the D90 particle size being no more than 25 or 15 times the D10 particle size.

[0011] Also provided is an aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising an aerosol-forming material and more than 0.1 weight percent carbon particles, the carbon particles having a volume average particle size greater than 3 micrometers and a particle size distribution having a D90 particle size and a D10 particle size, the D90 particle size being less than or equal to 40 times the D10 particle size.

[0012] Advantageously, the thermally conductive particles or carbon particles 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 result in a greater proportion of the aerosol-forming substrate reaching a temperature high enough to release volatile compounds, and therefore may result in a higher efficiency of use of the aerosol-forming substrate. Alternatively, or in addition, the increased 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.

[0013] Advantageously, a relatively narrow particle size distribution may provide a more homogeneous substrate with respect to thermal conductivity, which may mean that temperature gradients within the substrate are minimised in use.

[0014] Some or each of the thermally conductive particles or carbon particles may have a thermal conductivity of greater than 2, 5, 10, 20, 50, 100, 200, 500, or 1000 W / mK.

[0015] The or each of the thermally conductive particles or carbon particles may exhibit anisotropic thermal conductivity. The or each of the thermally conductive particles or carbon particles may have a thermal conductivity of greater than 2, 5, 10, 20, 50, 100, 200, 500, or 1000 W / mK in at least one direction.

[0016] Advantageously, increasing the thermal conductivity of the thermally conductive particles or carbon particles may increase the thermal conductivity of the aerosol-forming substrate.

[0017] Some or all of the thermally conductive particles may be non-metallic particles. Some or all of the thermally conductive particles may be carbon particles. Some or all of the thermally conductive particles may be graphite particles. Some or all of the thermally conductive particles may be expanded graphite particles. Some or all of the thermally conductive particles may be graphene particles.

[0018] Advantageously, particles such as those listed above, especially 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. This may be advantageous to avoid significantly increasing the density of the aerosol-forming substrate, which may increase the weight for a given volume of substrate, and therefore the transportation costs.

[0019] Expandable graphite is available in units of 2, 1.8, 1.5, 1.2, 1, 0.8, 0.5, 0.2, 0.1, 0.05, and 0.02 grams per cubic centimeter (g / cm 3 ) in some cases.

[0020] Expandable graphite is available in units 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 cubic centimeter (g / cm 3 ) in some cases.

[0021] 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, 0.1~0.5, 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 gram per cubic centimeter (g / cm 3 )

[0022] The carbon particles may comprise greater than 80, 90, 95, 98, 99, 99.5, or 99.9% by weight carbon. The carbon particles may consist of carbon except for trace impurities.

[0023] The thermally conductive particles may comprise no more than 80, 50, 20, 10, or 5 percent by weight of the aerosol-forming substrate. The thermally conductive particles may comprise no more than 0.1, 0.2, 0.5, 1, 2, 3, 5, 10, 20, or 50 percent by weight of the aerosol-forming substrate.

[0024] The carbon particles may comprise no more than 80, 50, 20, 10, or 5 percent by weight of the aerosol-forming substrate. The carbon particles may comprise no more than 0.1, 0.2, 0.5, 1, 2, 3, 5, 10, 20, or 50 percent by weight of the aerosol-forming substrate.

[0025] The thermally conductive particles may comprise 0.1-20, 0.2-20, 0.5-20, 1-20, 2-20, 3-20, 5-20, 0.1-15, 0.2-15, 0.5-15, 1-15, 2-15, 3-15, 5-15, 0.1-10, 0.2-10, 0.5-10, 1-10, 2-10, 3-10, or 5-10 percent by weight of the aerosol-forming substrate.

[0026] The carbon particles may comprise 0.1-20, 0.2-20, 0.5-20, 1-20, 2-20, 3-20, 5-20, 0.1-15, 0.2-15, 0.5-15, 1-15, 2-15, 3-15, 5-15, 0.1-10, 0.2-10, 0.5-10, 1-10, 2-10, 3-10, or 5-10 percent by weight of the aerosol-forming substrate.

[0027] It may be particularly preferred for the thermally conductive particles or carbon particles to comprise more than 1 percent by weight of the aerosol-forming substrate.

[0028] It may also be particularly preferred for the thermally conductive particles or carbon particles to comprise less than 20 percent by weight of the aerosol-forming substrate.

[0029] 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.

[0030] It may be particularly preferred that the thermally conductive particles or carbon particles comprise 1-20, 2-15, or 3-10 weight percent of the aerosol-forming substrate, especially when the thermally conductive particles are graphite or expanded graphite particles. This is because the inventors have found that for a particular aerosol-forming substrate, these weight percent ranges may provide a more consistent glycerol and nicotine delivery over approximately 12 puffs. Without wishing to be bound by theory, it is believed that this is because having less than 1, 2, or 3 weight percent of thermally conductive particles does not have a large enough effect on the thermal conductivity of the substrate, while more than 10, 15, or 20 weight percent of thermally conductive particles raises the local substrate temperature too high and too quickly, resulting in relatively high glycerol and nicotine delivery in initial puffs, but relatively low glycerol and nicotine delivery in subsequent puffs.

[0031] In addition, the inventors have surprisingly found that for a particular aerosol-forming substrate, the total yield of glycerol and nicotine over approximately 12 puffs appears to reach a maximum for substrates having 1-20, 2-15, or 3-10 weight percent thermally conductive particles. This may be advantageous because less substrate may be required to deliver an equivalent amount of glycerol and nicotine to the user. Data suggesting this from experiments performed by the inventors is shown in Table 1 below. [Table 1]

[0032] Some or all of the thermally conductive particles may be metal particles. Some or all of the thermally conductive particles may be copper particles. Some or all of the thermally conductive particles may be aluminum particles.

[0033] Advantageously, such particles may have high thermal conductivity and therefore may significantly improve the thermal conductivity of the aerosol-forming substrate.

[0034] The aerosol-forming substrate may be in the form of a rod, so that a rod of the aerosol-forming substrate may be provided.

[0035] 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., 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.

[0036] 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 from the upstream end to the downstream end of the rod of the aerosol-forming substrate.

[0037] The susceptor elements may be in the form of pins, rods, strips, or blades.

[0038] The susceptor element may have a length of 5 to 15 millimeters, 6 to 12 millimeters, 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 millimeters, 0.5 to 2 millimeters, or 0.5 to 1 millimeter.

[0039] Alternatively, there may be no susceptor material present within the aerosol-forming substrate or within the rod of the aerosol-forming substrate, or the thermally conductive particles may comprise or consist of one or more susceptor materials, or may be the only susceptor material present within the aerosol-forming substrate or within the rod of the aerosol-forming substrate, i.e., there may not be any susceptor elements present within the aerosol-forming substrate or within the rod of the aerosol-forming substrate, except for the thermally conductive particles or carbon particles.

[0040] Some or all of the thermally conductive particles or carbon particles may be susceptor particles, i.e., some or all of the particles may include or consist of a susceptor material. As such, the thermally conductive particles or carbon particles may be configured to be inductively heated.

[0041] Suitable susceptor materials, for example, materials for one or both of the susceptor elements and susceptor particles, include, but are not limited to, carbon, carbon-based materials, graphene, graphite, expanded graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Suitable susceptor materials may include ferromagnetic materials, for example, ferromagnetic alloys such as ferritic iron, 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 percent, preferably more than 20 percent, more preferably more than 50 percent, or more than 90 percent, of ferromagnetic or paramagnetic materials. Preferred susceptor materials may include metals, metal alloys, or carbon.

[0042] 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.

[0043] 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 of the aerosol-forming substrate.

[0044] The thermally conductive particles or carbon particles may have a particle size distribution having a D10 particle size, a D50 particle size, and a D90 particle size. In such a particle size distribution, 10% of the particles have a particle size equal to or less than the D10 particle size, and 90% of the particles have a particle size equal to or less than the D90 particle size. The D50 particle size is the median particle size, such that 50% of the particles have a particle size equal to or less than the D50 particle size.

[0045] The characteristics discussed below with respect to particle sizes of carbon particles (eg, D10, D50, volume average, and D90 particle sizes) may be equally applicable to particle sizes of thermally conductive particles.

[0046] The D90 particle size may be less than or equal to 50, 40, 30, 25, 20, 15, 10, 8, 5, or 3 times the D10 particle size. The D90 particle size may be greater than or equal to 2, 3, 5, or 8 times the D10 particle size.

[0047] The D90 particle size may be 3 to 50, 3 to 40, 3 to 30, 3 to 25, 3 to 20, 3 to 15, 3 to 10, 3 to 8, 3 to 5, 5 to 50, 5 to 40, 5 to 30, 5 to 25, 5 to 20, 5 to 15, 5 to 10, 5 to 8, 8 to 50, 8 to 40, 8 to 30, 8 to 25, 8 to 20, 8 to 15, 8 to 10, 10 to 50, 10 to 40, 10 to 30, 10 to 25, 10 to 20, 10 to 15, 15 to 50, 15 to 40, 15 to 30, 15 to 25, or 15 to 20 times the D10 particle size.

[0048] A preferred particle size distribution may have a D90 particle size of 3 to 25, or 3 to 15 times the D10 particle size. A particularly preferred particle size distribution may have a D90 particle size of 5 to 20, or 5 to 10 times the D10 particle size.

[0049] A compromise must be made regarding particle size distribution. A tighter particle size distribution may advantageously provide a more uniform thermal conductivity throughout the aerosol-forming substrate. 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.

[0050] The desired D10 and D90 particle sizes may be obtained by sieving. Thus, if desired, sieving may be used to obtain a narrow particle size distribution.

[0051] The D10 particle size of the carbon particles may be 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more. Each of the carbon particles may have a particle size of 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more.

[0052] The D10 particle size of the carbon particles may be less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 micrometers. Each of the carbon particles may have a particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 micrometers.

[0053] The D90 particle size of the carbon particles may be less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 micrometers. Each of the carbon particles may have a particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 micrometers.

[0054] The D90 particle size of the carbon particles may be 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more. Each of the carbon particles may have a particle size of 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more.

[0055] The carbon particles may have one or both of a D50 particle size and a volume average particle size of 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more.

[0056] The carbon particles may have one or both of a D50 particle size and a volume average particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3, or 2 micrometers.

[0057] The carbon particles may have a D50 particle size and / or a volume average particle size of 1 to 1000, preferably 35 to 1000, or more preferably 100 to 900 micrometers. Alternatively, or additionally, each of the carbon particles may have a particle size of 1 to 1000, preferably 35 to 1000, or more preferably 100 to 900 micrometers.

[0058] Surprisingly, the inventors have found that these relatively large particle size ranges are particularly effective in increasing the thermal conductivity of the aerosol-forming substrate when the aerosol-forming material includes or is in the form of one or more of cut filler, powder particles, granules, pellets, flakes, spaghetti, strips, or sheets. In addition, these relatively large particle sizes may advantageously adhere better to the aerosol-forming substrate than smaller particle sizes in the form of one or more of cut filler, powder particles, granules, pellets, flakes, spaghetti, strips, or sheets. It may also be easier to mix particles in this size range with tobacco particles of similar size used in some cut fillers. As such, these size ranges may be particularly preferred when the aerosol-forming material includes or is in the form of one or more of cut filler, powder particles, granules, pellets, flakes, spaghetti, strips, or sheets.

[0059] One or both of the D50 particle size and the volume average particle size of the carbon particles may be from 1 to 1000, preferably from 10 to 200, more preferably from 30 to 150, or even more preferably from 50 to 75 micrometers. Alternatively or additionally, each of the carbon particles may have a particle size of from 1 to 1000, preferably from 10 to 200, more preferably from 30 to 150, or even more preferably from 50 to 75 micrometers.

[0060] Surprisingly, the inventors have found that these relatively small particle size ranges are particularly effective in increasing the thermal conductivity of the aerosol-forming substrate when the aerosol-forming material includes or is in the form of a sheet, such as a collection of sheets. In addition, these relatively small particle sizes may advantageously result in a more homogeneous sheet of aerosol-forming material in terms of thermal conductivity and also result in a sheet with a more uniform thickness than when larger particle sizes are used. It may also be easier to mix particles in this size range with similarly sized tobacco particles used in some manufacturing processes to form aerosol-forming sheets. As such, these particle size ranges may be particularly preferred when the aerosol-forming material includes or is in the form of a sheet, such as a collection of sheets.

[0061] The carbon particles may have a volume average particle size of 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more.

[0062] It may be particularly preferred for the carbon particles to have a volume average particle size of greater than 10 micrometers.

[0063] The carbon particles may have a volume average particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3, or 2 micrometers.

[0064] The carbon particles may have a volume average particle size of 1 to 1000, 35 to 1000, or 100 to 900 micrometers. These particle size ranges may be particularly preferred when the aerosol-forming material includes or is in the form of one or more of cut filler, powder particles, granules, pellets, pieces, spaghetti, strips, or sheets.

[0065] The carbon particles may have a volume average particle size of 1 to 1000, 10 to 200, 30 to 150, or 50 to 75 micrometers. These volume average particle size ranges may be particularly preferred when the aerosol-forming material comprises or is in the form of a sheet, such as an assembly of sheets.

[0066] The carbon particles may have a volume average particle size that is at least 2, 3, 5, 8, 10, 15, or 20 times the number average particle size.

[0067] It may be particularly preferred that the thermally conductive particles are or include graphite particles.

[0068] The graphite particles may have a particle size distribution having a D10 particle size of 5 to 20, such as 10 to 14 micrometers, e.g., approximately 12 micrometers. The graphite particles may have a particle size distribution having a D50 particle size of 25 to 45 micrometers, e.g., approximately 35 micrometers. The graphite particles may have a particle size distribution having a D90 particle size of 45 to 75 micrometers, e.g., approximately 55 micrometers. Advantageously, such particles are commercially available and have been found by the inventors to provide a significant increase in the thermal conductivity of the aerosol-forming substrate.

[0069] It may be particularly preferred that the thermally conductive particles are or include expanded graphite particles.

[0070] The expanded graphite particles may have a particle size distribution with a D10 particle size of 5 to 20, such as 9 to 12 micrometers, for example approximately 10.5 micrometers. The expanded graphite particles may have a particle size distribution with a D50 particle size of 15 to 25 micrometers, for example approximately 20 micrometers. The expanded graphite particles may have a particle size distribution with a D90 particle size of 46 to 66 micrometers, for example approximately 56 micrometers. Advantageously, such particles are commercially available and have been found by the inventors to provide a significant increase in the thermal conductivity of the aerosol-forming substrate. The expanded graphite particles may also advantageously reduce the overall density of the aerosol-forming substrate.

[0071] Each of the thermally conductive particles or carbon particles may have three mutually perpendicular dimensions. The largest of the three dimensions may be no more than 10, 8, 5, 3, or 2 times greater than the smallest of the three dimensions. The largest of the three dimensions may be no more than 10, 8, 5, 3, or 2 times greater than the second largest of the three dimensions. Each of the three dimensions may be substantially equal. Each of the thermally conductive particles or carbon particles may be substantially spherical.

[0072] The thermally conductive particles or carbon particles may include at least 10, 20, 50, 100, 200, 500, or 1000 particles.

[0073] The thermally conductive particles or carbon particles may be substantially uniformly distributed throughout the aerosol-forming material. The aerosol-forming material may be considered a matrix. Hence, the thermally conductive particles or carbon particles may be substantially uniformly distributed throughout the matrix of the aerosol-forming material.

[0074] Advantageously, thermally conductive or carbon particles distributed substantially uniformly throughout the aerosol-forming material may result in a more uniform temperature distribution throughout the substrate in use.

[0075] Some or all of the thermally conductive particles or carbon particles may be surrounded by the aerosol-forming material. Advantageously, this may reduce the amount of heat that is wasted, i.e., it may reduce the amount of heat that is transferred from the particles to anything other than the aerosol-forming material.

[0076] Some or all of the thermally conductive particles or carbon particles may be coated onto the aerosol-forming material, for example onto the outer surface of the aerosol-forming material.

[0077] The thermally conductive particles or carbon particles may have a density equal to or less than the density of the aerosol-forming material. The thermally conductive particles or carbon particles may have a density 1, 2, 5, 10, 15, 20, 25, or 30% less than the density of the aerosol-forming material. The aerosol-forming substrate may have a density of 1050, 1000, 950, 900, 850, 800, 850, 800, 750, 700, or 650 kg / m 3 For the aerosol-forming substrate, the density may be from 500 to 900 kg / m 3 , e.g. 600~800kg / m 3 It may be particularly preferred to have a density of

[0078] Advantageously, the use of lower density particles may result in a lower density substrate, which may reduce the weight and therefore the shipping costs for a given volume of substrate.

[0079] The aerosol-forming substrate may have a thermal conductivity of greater than 0.06, 0.08, 0.1, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, or 0.17 W / mK. The aerosol-forming substrate may have a thermal conductivity of greater than 0.06, 0.08, 0.1, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, or 0.17 W / mK in at least one direction, for example in all directions.

[0080] 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 in the transverse or radial direction of more than 0.06, 0.08, 0.1, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, or 0.17 W / mK.

[0081] Advantageously, increasing the thermal conductivity of the substrate may reduce temperature gradients within the substrate during use. This may be particularly advantageous to increase the thermal conductivity of the substrate in the transverse direction, since large temperature gradients typically exist in the transverse direction in prior art substrates when used with a heating blade.

[0082] 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 vein fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco.

[0083] The aerosol forming material may include tobacco particles. The tobacco particles may have a particle size distribution having a D10 tobacco particle size, a D50 tobacco particle size, and a D90 tobacco particle size.

[0084] The D10 tobacco particle size may be between 1 and 20, or between 1 and 10 micrometers. The D10 tobacco particle size may be approximately 3 micrometers.

[0085] The D90 tobacco particle size may be between 40 and 200 or between 40 and 100 micrometers. The D90 tobacco particle size may be approximately 70 micrometers.

[0086] The D10 particle size of the thermally conductive particles or carbon particles may be 0.1-10, 0.2-5, 0.25-4, 0.5-2, or 0.8-1.25 times the D10 tobacco particle size. The D50 particle size of the thermally conductive particles or carbon particles may be 0.1-10, 0.2-5, 0.25-4, 0.5-2, or 0.8-1.25 times the D50 tobacco particle size. The D90 particle size of the thermally conductive particles or carbon particles may be 0.1-10, 0.2-5, 0.25-4, 0.5-2, or 0.8-1.25 times the D90 tobacco particle size. These ranges may advantageously allow for better mixing of the thermally conductive particles with the tobacco particles. This may advantageously result in a more homogenous aerosol-forming substrate.

[0087] 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, one or more aerosol formers selected from polyhydric alcohols (such as propylene glycol, polyethylene glycol, triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, and the like). It may be particularly preferred that the aerosol former is or includes glycerin.

[0088] The aerosol-forming substrate may comprise at least 1, 2, 5, 10, or 15 percent by weight of the aerosol former, for example the aerosol-forming substrate may comprise 12 to 25 percent by weight of the aerosol former.

[0089] 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.

[0090] The aerosol forming material may include nicotine.

[0091] The aerosol-forming material may include one or more cannabinoid compounds, such as one or more of tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), cannabidiol (CBD), cannabidiolic acid (CBDA), cannabinol (CBN), cannabigerol (CBG), cannabigerol monomethyl ether (CBGM), cannabivarin (CBV), cannabidivarin (CBDV), tetrahydrocannabivarin (THCV), cannabichromene (CBC), cannabicyclol (CBL), cannabichromevarin (CBCV), cannabigerovarin (CBGV), cannabielsoin (CBE), cannabicitran (CBT). The cannabinoid compound may preferably be CBD or THC. The cannabinoid compound may particularly preferably be CBD.

[0092] The aerosol-forming material may include one or more flavoring agents. The one or more flavoring agents may include one or more essential oils, such as eugenol, peppermint oil, and spearmint oil, one or both of menthol and eugenol, one or both of anethole and linalool, and one or more of herbaceous materials. Suitable herbaceous materials include herb leaves or other herbaceous materials from herbaceous plants, including, but not limited to, mint (such as peppermint and spearmint), lemon balm, basil, cinnamon, lemon basil, chives, coriander, lavender, sage, tea, thyme, and caraway. The one or more flavoring agents may include tobacco materials.

[0093] The aerosol forming material may include or be in the form of one or more of powder particles, granules, pellets, pieces, spaghetti, strips, or sheets.

[0094] The aerosol-forming material may include or be in the form of a cut filler. The cut width of the cut filler may be 0.3 to 2, 0.5 to 1.2, or 0.6 to 0.9 millimeters.

[0095] The cut width may affect the distribution of heat within the aerosol-forming substrate, the draw resistance of the aerosol-forming substrate, and the overall density of the aerosol-forming substrate. The inventors have found that the above cut width ranges may be desirable from the standpoint of heat distribution, draw resistance, and density.

[0096] The aerosol-forming material may comprise or be in the form of one or more sheets, e.g., a collection of 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 micrometers. The sheet or each sheet, e.g., a collection of sheets, may have a thickness of less than about 500, 400, or 300 micrometers. 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 micrometers. The sheet or each sheet, e.g., a collection of sheets, may have a thickness of approximately 235 micrometers.

[0097] The aerosol-forming material may include or be in the form of a plurality of strips. Each of the plurality of strips may extend substantially along a longitudinal axis of the aerosol-forming substrate or aerosol-generating article. Each of the plurality of strips may have a length of at least about 3, 5, or 10 millimeters. Each of the plurality of strips may have a width of less than about 3, 2, or 1 millimeters.

[0098] A number of particularly preferred aerosol-forming substrates are presented below.

[0099] A first particularly preferred aerosol-forming substrate is for use in a heated aerosol-generating article and comprises an aerosol-forming material and thermally conductive particles. The thermally conductive particles are carbon particles, such as graphite, expanded graphite, or graphene particles. The substrate comprises more than 0.1 weight percent of carbon particles. The carbon particles have a volume average particle size of more than 10 micrometers.

[0100] A second particularly preferred aerosol-forming substrate is for use in a heated aerosol-generating article and comprises an aerosol-forming material and thermally conductive particles. The thermally conductive particles are carbon particles, such as graphite, expanded graphite, or graphene particles. The substrate comprises more than 0.1 weight percent of the carbon particles. The carbon particles have a volume average particle size of 1 to 1000 micrometers. The aerosol-forming material comprises or is in the form of one or more of cut filler, powder particles, granules, pellets, pieces, spaghetti, strips, or sheets. Thus, as explained in more detail above, it may be preferred for the particles of this substrate to have a volume average particle size of 35 to 1000, or 100 to 900 micrometers.

[0101] A third particularly preferred aerosol-forming substrate is for use in a heated aerosol-generating article and comprises an aerosol-forming material and thermally conductive particles. The thermally conductive particles are carbon particles, such as graphite, expanded graphite, or graphene particles. The substrate comprises more than 0.1 weight percent of the carbon particles. The carbon particles have a volume average particle size of 1 to 1000 micrometers. The aerosol-forming material comprises or is in the form of a sheet, such as an assembly of sheets. Thus, as explained in more detail above, it may be preferred for the particles of this substrate to have a volume average particle size of 10 to 200, 30 to 150, or 50 to 75 micrometers.

[0102] As will be apparent to those skilled in the art after reading this disclosure, the features described above in relation to the aerosol-forming substrate as applicable may be equally applicable to these first, second and third preferred aerosol-forming substrates.

[0103] According to the present disclosure, there is provided an aerosol-generating article comprising an aerosol-forming substrate. Any of the features described above with respect to the aerosol-forming substrate may be applicable to the aerosol-forming substrate of the aerosol-generating article. The aerosol-forming substrate may be any of the first preferred aerosol-forming substrate, the second preferred aerosol-forming substrate, or the third preferred aerosol-forming substrate described above.

[0104] The aerosol generating article may be for use with an electrical aerosol generating device.

[0105] The aerosol-generating article may comprise multiple elements. The multiple elements may be assembled in the form of a rod.

[0106] 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.

[0107] The aerosol-generating article may comprise an intermediate hollow section. The intermediate hollow section may be located between the rod of the aerosol-generating substrate and the mouthpiece element. The intermediate hollow section may comprise 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.

[0108] 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.

[0109] 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 becoming dislodged from the article. The support element may advantageously provide support for the article and may also 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.

[0110] The components of the aerosol-generating article may be assembled with a suitable wrapper, for example cigarette paper. The cigarette paper may be any suitable material for wrapping the components of the aerosol-generating article into the form of a rod. Suitable materials for wrappers are well known in the art. The cigarette paper may grip the components of the aerosol-generating article when the article is assembled. The cigarette paper may hold the components in place within the rod.

[0111] 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 for allowing a heating pin, rod or blade to pass therethrough 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, 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.

[0112] The upstream element may have an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The upstream 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 upstream element may have an outer diameter of approximately 7.2 millimeters.

[0113] The upstream element may have a length of 1 to 10, 3 to 8, or 4 to 6 millimeters. The upstream element may have a length of about 5 millimeters.

[0114] Advantageously, the upstream element may prevent a consumer from seeing the thermally conductive particles or carbon particles through the upstream end of the article.

[0115] 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 in a longitudinal direction. Airflow through the interior cavity may be substantially unrestricted. Thus, the hollow tube may not contribute substantially to the resistance to withdrawal (RTD) of the article. The wall thickness of the hollow tube may be between 2 and 4 millimeters.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] The aerosol cooling element may comprise a second hollow tube, for example a substantially cylindrical second hollow tube, or may be a 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.

[0121] The aerosol cooling element may include or be formed of any suitable material or combination of materials. For example, the aerosol cooling element may include or be formed of 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 of cellulose acetate.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] The aerosol cooling element may have a length of at least about 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.

[0126] The mouthpiece element may comprise a filtration material, for example a fibrous filtration material. The mouthpiece element may comprise or be a plug of cellulose acetate. The mouthpiece element may be translucent or opaque. Advantageously, the mouthpiece element may prevent the consumer from seeing the thermally conductive particles or carbon particles through the downstream end of the article.

[0127] The mouthpiece element may be particularly beneficial in aerosol-generating articles that include an aerosol-forming substrate that includes thermally conductive particles, such as carbon particles, because the mouthpiece element may reduce the likelihood that the thermally conductive particles will be inhaled.

[0128] 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.

[0129] 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.

[0130] Advantageously, a longer mouthpiece element may be more resilient to deformation or may be better adapted to recover its original shape after deformation, and may provide improved grip by the consumer to facilitate insertion of the aerosol-generating article into the heating device.In addition, a longer mouthpiece element may provide a higher level of filtration and removal of undesirable aerosol components, thus allowing a higher quality aerosol to be delivered.In addition, 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.

[0131] 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 approximately 45 millimeters.

[0132] 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 7.25 millimeters.

[0133] According to the present disclosure, there is provided an aerosol generating system comprising an aerosol generating article as described above and an aerosol generating device.

[0134] 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.

[0135] The aerosol generating device may be configured to heat the aerosol-generating article. The aerosol generating device may be configured to resistively heat the aerosol-generating article. 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 the track. The heating element may be in the form of a pin, rod or blade.

[0136] The aerosol-generating device may be configured to inductively heat the aerosol-generating article. The device may comprise an inductor, such as an inductor 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., in the susceptor material of the thermally conductive particles, or in the susceptor material of the 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, and thereby heat the aerosol-forming substrate in use.

[0137] According to the present disclosure, there is provided a method of forming an aerosol-forming substrate. The method may include forming a slurry, for example a slurry including an organic material and thermally conductive particles. The method may include homogenizing the slurry. The method may include casting the slurry. The method may include drying the slurry to form the aerosol-forming substrate.

[0138] Therefore, forming a slurry comprising an organic material and thermally conductive particles; homogenizing the slurry; and c. casting and drying the slurry to form the aerosol-forming substrate.

[0139] Any feature described with respect to the aerosol-forming substrate may be applicable to the aerosol-forming substrate of this method. The thermally conductive particles may be carbon particles. Any feature described with respect to the thermally conductive particles or carbon particles may be applicable to the thermally conductive particles of this method. Any feature described with respect to the aerosol-forming material above may be applicable to the aerosol-forming material of this method.

[0140] The method may be used, for example, to form any of the aerosol-forming substrates described above, or any of the first particularly preferred aerosol-forming substrate, the second particularly preferred aerosol-forming substrate, or the third particularly preferred aerosol-forming substrate described above.

[0141] The slurry may include one or more of organic material, thermally conductive particles, water, one or more binders, one or more aerosol formers, tobacco particles, tobacco fibers, non-tobacco fibers, one or more humectants, one or more plasticizers, one or more flavorants, one or more fillers, one or more aqueous solvents, and one or more non-aqueous solvents. Thus, forming the slurry may include mixing one or more of the above components of the slurry.

[0142] The organic material may include one or both of tobacco material and herbaceous material. The organic material may be shredded. For example, the organic material may be or include finely shredded tobacco material. The organic material may include or be in the form of a powder, such as tobacco powder.

[0143] When the slurry includes tobacco particles, the tobacco particles may have a particle size distribution having a D10 tobacco particle size, a D50 tobacco particle size, and a D90 tobacco particle size.

[0144] The D10 tobacco particle size may be between 1 and 20, or between 1 and 10 micrometers. The D10 tobacco particle size may be approximately 3 micrometers.

[0145] The D90 tobacco particle size may be between 40 and 200 or between 40 and 100 micrometers. The D90 tobacco particle size may be approximately 70 micrometers.

[0146] The D10 particle size of the thermally conductive particles or carbon particles may be 0.1-10, 0.2-5, 0.25-4, 0.5-2, or 0.8-1.25 times the D10 tobacco particle size. The D50 particle size of the thermally conductive particles or carbon particles may be 0.1-10, 0.2-5, 0.25-4, 0.5-2, or 0.8-1.25 times the D50 tobacco particle size. The D90 particle size of the thermally conductive particles or carbon particles may be 0.1-10, 0.2-5, 0.25-4, 0.5-2, or 0.8-1.25 times the D90 tobacco particle size. These ranges may advantageously allow for better mixing of the thermally conductive particles with the tobacco particles. This may advantageously result in a more homogenous aerosol-forming substrate.

[0147] Suitable 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 locust bean gum and hydroxypropyl locust bean gum), 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 includes guar.

[0148] 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 monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.). It may be particularly preferred for the aerosol former to be or include glycerin.

[0149] Forming the slurry may include premixing one or more binders with one or more aerosol formers to form a premix. Forming the slurry may include mixing additional components with the premix. Forming the slurry may include mixing thermally conductive particles with the premix.

[0150] Advantageously, premixing the binder with the aerosol former may reduce the likelihood of the binder gelling, for example, when the binder comes into contact with water, which may lead to unintended non-uniform mixing of the slurry.

[0151] Homogenizing the slurry may include mixing the slurry using mixing equipment such as a high shear mixer.

[0152] Casting the slurry may include casting the slurry onto a support surface, which may be the surface of a moving conveyor belt.

[0153] Drying the slurry may form a sheet of the aerosol-forming substrate. The sheet may be collected and cut.

[0154] According to the present disclosure, there is provided a method of forming an aerosol-generating article comprising the method described above.

[0155] The method may include preparing a rod or plug of the aerosol-forming substrate.

[0156] The method may include assembling the aerosol-generating article from a plurality of components, the plurality of components including an aerosol-forming substrate, for example a rod or plug of an aerosol-forming substrate.

[0157] The method may include enclosing components of the aerosol-generating article in a wrapper, for example enclosing one or more of the upstream element, the aerosol-forming substrate, the aerosol cooling element, the support element, and the mouthpiece element in a wrapper.

[0158] According to the present disclosure, there is provided a second method of forming an aerosol-forming substrate. The method may include providing an aerosol-forming material. The method may include coating thermally conductive particles onto the aerosol-forming material to form the aerosol-forming substrate.

[0159] Therefore, Providing an aerosol forming material; and coating thermally conductive particles onto an aerosol-forming material to form an aerosol-forming substrate.

[0160] Any feature described above with respect to the aerosol-forming substrate may be applicable to the aerosol-forming substrate of this second method. The thermally conductive particles may be carbon particles. Any feature described above with respect to the thermally conductive particles or carbon particles may be applicable to the thermally conductive particles of this second method. Any feature described above with respect to the aerosol-forming material may be applicable to the aerosol-forming material of this second method.

[0161] The method may be used to form any of the aerosol-forming substrates described above, or any of the first, second or third particularly preferred aerosol-forming substrates described above.

[0162] For the second method, the aerosol-forming material may include or be in the form of one or more of cut filler, powder particles, granules, pellets, pieces, spaghetti, strips, or sheets. The cut width of the cut filler may be 0.3 to 2, 0.5 to 1.2, or 0.6 to 0.9 millimeters. One of ordinary skill in the art will know suitable methods for providing such an aerosol-forming material.

[0163] The method may include coating thermally conductive particles onto the aerosol-forming material prior to adding one or more flavorants onto the aerosol-forming material.

[0164] According to the present disclosure there is provided a method of forming an aerosol-generating article comprising the second method described above.

[0165] The method may include preparing a rod or plug of the aerosol-forming substrate.

[0166] The method may include assembling the aerosol-generating article from a plurality of components, the plurality of components including an aerosol-forming substrate, for example a rod or plug of an aerosol-forming substrate.

[0167] The method may include enclosing components of the aerosol-generating article in a wrapper, for example enclosing one or more of the upstream element, the aerosol-forming substrate, the aerosol cooling element, the support element, and the mouthpiece element in a wrapper.

[0168] 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.

[0169] As used herein, the term "thermally conductive particles" may refer to particles having a thermal conductivity greater than 1 W / mK. The particles may exhibit anisotropic thermal conductivity. In this case, the term "thermally conductive particles" may refer to particles having a thermal conductivity greater than 1 W / mK in at least one direction.

[0170] 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) with spacing between the carbon layers that is greater than the spacing found between the carbon layers in regular graphite. Expanded graphite may have carbon layers with elements or compounds intercalated into the spaces between the carbon layers.

[0171] As used herein, the term "particle size" may refer to a single dimension and may be used to characterize the size of a given particle. The dimension may be the diameter of a spherical particle that occupies the same volume as the given particle. All particle sizes and particle size distributions herein may be obtained using standard laser diffraction techniques. Particle sizes and particle size distributions as described herein may be obtained using commercially available sensors, for example, Sympatec's HELOS laser diffraction sensor.

[0172] As used herein, the term "volume average particle size" may refer to the average calculated using the following formula, where d[4,3] is the volume average particle size and d is the particle size:

number

[0173] In other words, the volume average particle size may refer to the average calculated by dividing the sum of the fourth powers of the particle sizes by the sum of the cubes of the particle sizes.

[0174] As used herein, unless otherwise specified, the term "density" may be used to refer to true density. Therefore, unless otherwise specified, the density of a powder or particles may refer to the true density of the powder or particles (rather than the bulk density of the powder or particles, which can vary widely depending on how the powder or particles are handled). Measurement of true density can be performed using a number of standard methods, which are often based on Archimedes' principle. The most widely used method used to measure the true density of a powder involves placing and weighing the powder inside a container of known volume (pycnometer). 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).

[0175] As used herein, the term "aerosol-generating article" may refer to an article that is capable of generating or emitting an aerosol.

[0176] As used herein, the term "heated aerosol-generating article" may refer to an article that is configured to generate or emit an aerosol when heated.

[0177] As used herein, the term "longitudinal direction" 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.

[0178] As used herein, the term "transverse" may refer to a direction perpendicular to the longitudinal axis.

[0179] As used herein, the term "aerosol-generating device" may refer to a device for use with an aerosol-generating article to enable the generation or emission of an aerosol.

[0180] As used herein, the term "assembly of a sheet" may refer to an aerosol-forming substrate, or a sheet of an aerosol-generating article that is spiraled, folded, or otherwise compressed or clamped in a direction substantially transverse to the longitudinal axis of the aerosol-forming substrate, or aerosol-generating article.

[0181] As used herein, the term "sheet" may 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.

[0182] As used herein, the term "strip" may refer to a generally planar, laminar element having a width and length that is substantially greater than its thickness. The width of a strip may be greater than its thickness, e.g., at least 2, 3, 5, or 10 times its thickness. The length of a strip may be greater than its width, e.g., at least 2, 3, 5, or 10 times its width.

[0183] As used herein, the term "aerosol former" 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 and stable aerosol. The aerosol may be substantially resistant to thermal decomposition at the operating temperature of the aerosol-forming substrate or aerosol-generating article.

[0184] As used herein, the term "aerosol cooling element" may refer to a component of an aerosol-generating article that is located downstream of an aerosol-forming substrate, such that, in use, an aerosol formed by the substrate or by volatile compounds released from the aerosol-forming substrate passes through and is cooled by the aerosol cooling element before being inhaled by a user.

[0185] As used herein, the term "rod" may refer to a generally cylindrical element of substantially circular, oval, or elliptical cross-section.

[0186] As used herein, the term "crimped" may refer to a sheet having a plurality of substantially parallel ridges or corrugations. When present in a component of an aerosol-generating article, the substantially parallel ridges or corrugations may extend longitudinally relative to the aerosol-generating article.

[0187] As used herein, the term "aeration level" may refer to the volume ratio of the airflow entering the aerosol-generating article through the ventilation zone (ventilation airflow) to the sum of the aerosol airflow and the ventilated airflow. The higher the aeration level, the higher the dilution of the aerosol stream delivered to the consumer.

[0188] 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 described above, for example, with any one or more of the features of other examples, embodiments, or aspects described herein. EXAMPLES

[0189] Example 1. An aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising thermally conductive particles and an aerosol-forming material.

[0190] Example 2. An aerosol-forming substrate according to Example 1, wherein each of the thermally conductive particles has a thermal conductivity of greater than 1, 2, 5, 10, 20, 50, 100, 200, 500, or 1000 W / mK.

[0191] Example 3. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles comprise no more than 80, 50, 20, 10, or 5 percent by weight of the aerosol-forming substrate.

[0192] Example 4. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles comprise 0.1, 0.2, 0.5, 1, 2, 3, 5, 10, 20, or 50 percent by weight or more of the aerosol-forming substrate.

[0193] Example 5. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles comprise 1-20, 2-20, 3-20, 5-20, 3-15, 5-15, or 3-10 percent by weight of the aerosol-forming substrate.

[0194] Example 6. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are non-metallic particles.

[0195] Example 7. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are carbon particles.

[0196] Example 8. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are graphite particles.

[0197] Example 9. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are expanded graphite particles.

[0198] Example 10. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are graphene particles.

[0199] Example 11. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are metal particles.

[0200] Example 12. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are copper particles.

[0201] Example 13. An aerosol-forming substrate according to any preceding example, wherein some or all of the thermally conductive particles are aluminum particles.

[0202] Example 14. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a particle size distribution having a D10 particle size, and a D90 particle size, and the D90 particle size is less than or equal to 50, 40, 30, 25, 20, 15, 10, 8, 5, or 3 times the D10 particle size.

[0203] Example 15. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a particle size distribution such that the D10 particle size of the thermally conductive particles is 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more.

[0204] Example 16. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a particle size distribution such that the D90 particle size of the thermally conductive particles is less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 micrometers.

[0205] Example 17. The aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a particle size distribution such that the D50 particle size of the thermally conductive particles is 1-1000, 35-1000, or 100-900 micrometers.

[0206] Example 18. The aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a particle size distribution such that the D50 particle size of the thermally conductive particles is 1-1000, 10-200, 30-150, or 50-75 micrometers.

[0207] Example 19. An aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has a particle size of 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more.

[0208] Example 20. An aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has a particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3, or 2 micrometers.

[0209] Example 21. The aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has a particle size of 1 to 1000, 35 to 1000, or 100 to 900 micrometers.

[0210] Example 22. The aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has a particle size of 1-1000, 10-200, 30-150, or 50-75 micrometers.

[0211] Example 23. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a volume average particle size of 1, 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 micrometers or more.

[0212] Example 24. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a volume average particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 micrometers.

[0213] Example 25. The aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a volume average particle size of 1 to 1000, 35 to 1000, or 100 to 900 micrometers.

[0214] Example 26. The aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles have a volume average particle size of 1 to 1000, 10 to 200, 30 to 150, or 50 to 75 micrometers.

[0215] Example 27. An aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has three mutually perpendicular dimensions, and the largest of the three dimensions is no more than 10 times, 8 times, 5 times, 3 times, or 2 times the smallest of the three dimensions.

[0216] Example 28. An aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has three mutually perpendicular dimensions, the largest of the three dimensions being no more than 10 times, 8 times, 5 times, 3 times, or 2 times the second largest of the three dimensions.

[0217] Example 29. The aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles is substantially spherical.

[0218] Example 30. The aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles comprise at least 10, 20, 50, 100, 200, 500, or 1000 particles.

[0219] Example 31. An aerosol-forming substrate according to any preceding example, wherein the or each of the thermally conductive particles comprises a susceptor material.

[0220] Example 32. An aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has a lower density than the aerosol-forming material.

[0221] Example 33. An aerosol-forming substrate according to any preceding example, wherein each of the thermally conductive particles has a density at least 1, 2, 5, 10, 15, 20, 25, or 30% less than the density of the aerosol-forming material.

[0222] Example 34. An aerosol-forming substrate according to any preceding example, wherein the aerosol-forming substrate has a thermal conductivity greater than 0.06, 0.08, 0.1, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, or 0.17 W / mK.

[0223] Example 35. The aerosol-forming substrate is 1050, 1000, 950, 900, 850, 800, 850, 800, 750, 700, or 650 kg / m 3 Density less than 500-900, or 600-800 kg / m 3 The aerosol-forming substrate according to any preceding embodiment, having a density of

[0224] Example 36. An aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises one or more organic materials, such as tobacco.

[0225] Example 37. The aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises one or more of herb leaves, tobacco leaves, tobacco vein fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco.

[0226] Example 38. An aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises one or more aerosol formers.

[0227] Example 39. The aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises one or more aerosol formers selected from 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).

[0228] Example 40. The aerosol-forming substrate according to any preceding example, wherein the aerosol-forming substrate comprises glycerin.

[0229] Example 41. An aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises nicotine.

[0230] Example 42. The aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises or is in the form of one or more of cut filler, powder particles, granules, pellets, pieces, spaghetti, strips, or sheets.

[0231] Example 43. An aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises or is in the form of one or more sheets.

[0232] Example 44. An aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises, or is in the form of, an assembly of one or more sheets.

[0233] Example 45. An aerosol-forming substrate according to example 44, wherein the collection of sheets, or each collection of sheets, has a width of at least about 10, 25, 50, or 100 mm.

[0234] Example 46. An aerosol-forming substrate according to any preceding example, wherein the aerosol-forming material comprises or is in the form of a plurality of strips.

[0235] Example 47. An aerosol-forming substrate according to example 46, wherein each of the plurality of strips extends substantially along the longitudinal axis of the aerosol-generating article.

[0236] Example 48. An aerosol-forming substrate according to any of Examples 46-47, wherein each of the plurality of strips has a length of at least about 3, 5, or 10 mm.

[0237] Example 49. An aerosol-forming substrate according to any of Examples 46-48, wherein each of the plurality of strips has a width of less than about 3, 2, or 1 mm.

[0238] Example 50. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles are carbon particles and account for more than 0.1 weight percent of the aerosol-forming substrate, and the carbon particles have a volume average particle size greater than 3 micrometers, and a particle size distribution having a D90 particle size and a D10 particle size, the D90 particle size being less than or equal to 40 times the D10 particle size.

[0239] Example 51. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles are carbon particles and comprise more than 0.1 weight percent of the aerosol-forming substrate, and the carbon particles have a volume average particle size of more than 10 micrometers.

[0240] Example 52. An aerosol-forming substrate according to any preceding example, wherein the thermally conductive particles are carbon particles and account for more than 0.1 weight percent of the aerosol-forming substrate, and the carbon particles have a particle size distribution having a D90 particle size and a D10 particle size, the D90 particle size being no more than 25 or 15 times the D10 particle size. Example 53. An aerosol-generating article comprising an aerosol-forming substrate according to any preceding example.

[0241] Example 54. An aerosol-generating article according to Example 53, wherein the aerosol-generating article is for use with an electrical aerosol generating device.

[0242] Example 55. An aerosol generating system comprising an aerosol generating article according to Example 53 or 54 and an electrical aerosol generating device.

[0243] Example 56. An aerosol generating system according to example 55, wherein the electrical aerosol generating device is configured to resistively heat the aerosol-generating article in use.

[0244] Example 57. An aerosol generating system according to example 55, wherein the electrical aerosol generating device is configured to inductively heat the aerosol-generating article during use.

[0245] Example 58. A method of forming an aerosol-forming substrate, comprising: forming a slurry comprising an organic material and thermally conductive particles; homogenizing the slurry; casting and drying the slurry to form an aerosol-forming substrate.

[0246] Example 59. A method according to example 58, wherein the method is a method of forming an aerosol-forming substrate according to any of examples 1-52.

[0247] Example 60. The method according to any of examples 58-59, wherein the slurry comprises water.

[0248] Example 61. The method according to any of examples 58-60, wherein the slurry comprises cellulose fibers.

[0249] Example 62. The method according to any of examples 58-61, wherein the slurry comprises one or more binders.

[0250] Example 63. The method according to any of examples 58-62, wherein the slurry comprises one or more aerosol formers.

[0251] Example 64. The method according to any of examples 58-63, wherein the organic material is or comprises tobacco material, such as tobacco powder.

[0252] Example 65. A method of forming an aerosol-forming substrate, comprising: Providing an aerosol forming material; and coating the thermally conductive particles onto the aerosol-forming material to form an aerosol-forming substrate.

[0253] Example 66. A method according to example 65, wherein the method is a method of forming an aerosol-forming substrate according to any of examples 1-52.

[0254] Example 67. The method according to any of Examples 65-66, wherein the aerosol-forming material comprises an organic material.

[0255] Example 68. The method according to example 67, wherein the organic material is or comprises tobacco material.

[0256] Example 69. An aerosol-forming substrate for use in a heated aerosol-generating article, comprising an aerosol-forming material and more than 0.1 weight percent carbon particles, the carbon particles having a volume average particle size greater than 10 micrometers, the carbon particles having a particle size distribution having a D10 particle size and a D90 particle size, the D90 particle size being less than 20 times the D10 particle size.

[0257] Example 70. An aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising an aerosol-forming material and greater than 0.1 weight percent carbon particles, the carbon particles having a volume average particle size greater than 10 micrometers, and the carbon particles consisting of one or both of expanded graphite particles and graphene particles.

[0258] Example 71. An aerosol-forming substrate for use in a heated aerosol-generating article, the aerosol-forming substrate comprising an aerosol-forming material and 0.1 to 15 weight percent carbon particles, the carbon particles having a volume average particle size of 10 to 75 micrometers.

[0259] The embodiments will now be further described with reference to the figures. [Brief description of the drawings]

[0260] [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-sectional view of a second embodiment of an aerosol-generating article. [Diagram 3] FIG. 3 shows a schematic cross-sectional view of a first embodiment of an aerosol generation system. [Figure 4] FIG. 4 shows a schematic cross-sectional view of a second embodiment of an aerosol generation system. [Diagram 5] FIG. 5 shows a schematic cross-sectional view of a third embodiment of an aerosol-generating article. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0261] 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 at a location downstream of the rod of aerosol-forming substrate 12. Furthermore, the aerosol-generating article 10 comprises an upstream section 16 at a location upstream of the rod of aerosol-forming substrate 12. The aerosol-generating article 10 thus extends from an upstream or distal end 18 to a downstream or proximal or mouth end 20.

[0262] The aerosol-generating article has an overall length of about 45 millimeters.

[0263] 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.

[0264] 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.

[0265] 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 from an upstream end 30 of the first hollow tubular segment all the way to a downstream end 32 of the first hollow tubular segment 20. The interior cavity 28 is substantially empty, thereby allowing substantially unrestricted airflow along the interior cavity 28. 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.

[0266] 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 ), therefore, the peripheral wall thickness of the first hollow tubular segment 26 is approximately 2.67 millimeters.

[0267] 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.

[0268] 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 therefore approximately 2 millimeters. FTS ) and the inner diameter (D STS ) is about 0.75.

[0269] 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 includes a circumferential row of perforations through the paper wrapper 70, and the ventilation level of the aerosol-generating article 10 is approximately 25 percent.

[0270] 1, the downstream section 14 further comprises a mouthpiece element 42 at a location 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.

[0271] Mouthpiece element 42 is provided in the form of a cylindrical plug of low density cellulose acetate.

[0272] 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 approximately 0.6.

[0273] The rod 12 of the aerosol-forming substrate has an outer diameter of about 7.25 millimeters, and a length of about 12 millimeters.

[0274] 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 in longitudinal alignment with the rod 12. In the embodiment of Figure 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.

[0275] 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 surrounded by a paper wrapper 70 .

[0276] The rod 12 of the aerosol-forming substrate comprises an aerosol-forming material and thermally conductive particles 44. The aerosol-forming material comprises a reconstituted and assembled sheet comprising tobacco material and glycerin. The thermally conductive particles 44 are carbon particles, specifically expanded graphite particles, and have a particle size distribution with a D10 particle size of 6.6 micrometers, a D50 particle size of 20 micrometers, and a D90 particle size of 56 micrometers. Each of the expanded graphite particles has a particle size greater than 2 micrometers and less than 100 micrometers. The expanded graphite particles have a volume average particle size of approximately 35 micrometers. Each of the expanded graphite particles is substantially spherical in shape. The expanded graphite particles have a density less than 1000 kilograms per cubic meter. The aerosol-forming substrate comprising the aerosol-forming material and the thermally conductive particles 44 has a combined density of approximately 760 kilograms per cubic meter. The expanded graphite particles make up approximately 5% by weight of the aerosol-forming substrate.

[0277] The rod 12 of the aerosol-forming substrate is prepared by the following steps: premixing a binder, guar gum, with an aerosol former, glycerin, to form a first premix; premixing the finely shredded tobacco material with a powder comprised of expanded graphite particles 44 and having a bulk density of approximately 0.065 grams per cubic centimeter to form a second premix; mixing the first premix and the second 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 the aerosol-forming substrate; a) assembling and cutting a large sheet of the aerosol-forming substrate to form rods 12 of said aerosol-forming substrate.

[0278] After forming the aerosol-forming substrate rod 12 , the aerosol-generating article 10 is assembled by positioning the various components of the article 10 and wrapping the components within a wrapper 70 .

[0279] Figure 2 shows a schematic cross-sectional view of a second embodiment of an aerosol-generating article 11. 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 13. The same reference numbers are used for identical components in the embodiments of Figures 1 and 2.

[0280] In the second embodiment of the rod 13, the aerosol-forming substrate comprises an aerosol-forming material and thermally conductive particles 45. The aerosol-forming material comprises tobacco and glycerin, and is in the form of cut filler. The cut filler comprises pieces of the aerosol-forming material, the pieces having a width of 0.3 to 2 millimeters. The thermally conductive particles 45 are graphite particles, or rather expanded graphite particles, and have a particle size distribution with a D10 particle size of 6 micrometers, a D50 particle size of 21 micrometers, and a D90 particle size of 55 micrometers. Each of the graphite particles has a particle size greater than 2 micrometers and less than 100 micrometers. The graphite particles have a volume average particle size of approximately 35 micrometers. Each of the graphite particles is substantially spherical in shape. The graphite particles have a density of approximately 2200 kilograms per cubic meter. The aerosol-forming substrate comprising the aerosol-forming material and the thermally conductive particles 45 has a composite density of approximately 960 kilograms per cubic meter. The graphite particles comprise approximately 5% by weight of the aerosol-forming substrate.

[0281] The rod 13 of the aerosol-forming substrate is prepared by the following steps: premixing a binder, guar gum, with an aerosol former, glycerin, to form a first premix; - premixing the finely shredded tobacco material with water to form a second premix; mixing the first premix with the second premix 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 reconstituted, substantially homogeneous, tobacco-containing, aerosol-forming material; shredding a large sheet of the reconstituted and substantially homogenous aerosol-forming material to form a cut filler; mixing a powder of graphite particles 45 having a bulk density of approximately 560 kilograms per cubic meter with the cut filler, thereby coating the graphite particles 45 onto the cut filler; adding flavoring agents to the cut filler having the graphite particles 45 coated thereon; forming the cut filler (having graphite particles 45 and flavourings) into plugs for use as rods 13 of the aerosol-forming substrate.

[0282] After forming the rod 13 of aerosol-forming substrate, the aerosol-generating article 11 is assembled by positioning the various components of the article 11 and wrapping the components within a wrapper 70 .

[0283] 3 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.

[0284] 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.

[0285] 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 positioned within the cavity and extends longitudinally from the base of the cavity.

[0286] 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 the battery 104 can pass an electrical current through the electrically resistive track and heat the electrically resistive track and the heating blade 108 to an operating temperature.

[0287] In use, the user inserts the article 10 into the cavity and causes the heating blade 108 to penetrate the upstream element 46 of the article 10 and the rod 12 of the aerosol-forming substrate. Figure 3 shows the article 10 inserted into the cavity of the device 102.

[0288] 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.

[0289] When a user puffs on the article 10, air is caused to flow 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 pass a current through the electrically resistive track and heat the heating blade 108. This heats the rod 12 of the aerosol-forming substrate, which is in contact with the heating blade 108.

[0290] The expanded graphite particles 44 have a significantly higher thermal conductivity than the surrounding aerosol-forming material. As such, these particles may act as localized hot spots and provide a more uniform temperature throughout the aerosol-forming substrate, particularly in the radial direction from the heating blade 108, where prior art substrates would have significant temperature gradients. This may result in a greater proportion of the aerosol-forming substrate reaching a temperature high enough to release volatile compounds, and therefore a more efficient use of the aerosol-forming substrate.

[0291] Heating of the aerosol-forming substrate causes the aerosol-forming substrate to release 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 to form an aerosol as they pass through the internal cavities 28, 36 of the support element and the aerosol cooling element. The aerosol then passes through the mouthpiece element 42, which may filter out undesirable particles that may be entrained in the airflow and enter the user's mouth.

[0292] When the user stops inhaling on the article 10, the air flow 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 passing through the electrically resistive track to zero.

[0293] After smoking the article 10 a certain number of times, the user may choose to replace the article 10 with an unused article.

[0294] 4 shows a schematic cross-sectional view of a second embodiment of an aerosol generating system 200. The system 200 comprises an aerosol generating device 202 and the aerosol-generating article 11 of FIG.

[0295] 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.

[0296] 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 spirals around the cavity.

[0297] The battery 204 is coupled to the inductor coil 208 such that an alternating current can be passed through the inductor coil 208 .

[0298] In use, a user inserts an item 11 into the cavity. Figure 4 shows an item 11 inserted into the cavity of the device 202.

[0299] 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.

[0300] When a user puffs on the article 11, air is caused to flow 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 accordingly sends a signal to the controller 206. The controller 206 then controls the battery 204 to pass an alternating current through the inductor coil 208. This generates a varying electromagnetic field in the inductor coil 208. The rod 13 of the aerosol-forming substrate is located within this varying electromagnetic field, and the material of the particles 45, graphite, is a susceptor material. Hence, the varying electromagnetic field induces eddy currents in the particles 45. This causes the particles 45 to heat up, thereby also heating the nearby aerosol-forming material.

[0301] 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 to form an aerosol as they pass through the internal cavities 28, 36 of the support element and the aerosol cooling element. The aerosol then passes through the mouthpiece element 42, which may filter out undesirable particles that may be entrained in the airflow and enter the user's mouth.

[0302] When the user stops inhaling on the article 11, the air flow 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 passing through the electrically resistive track to zero.

[0303] After taking a number of puffs on the article 11, the user may choose to replace the article 11 with a new article.

[0304] Figure 5 shows a schematic cross-sectional view of a third embodiment of an aerosol-generating article 510. This third 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 identical components in the embodiments of Figures 1 and 5.

[0305] The rod 512 of the aerosol-forming substrate of the third embodiment in FIG. 5 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 third embodiment in FIG. 5 additionally includes an elongated susceptor element 580.

[0306] The susceptor element 580 is disposed substantially longitudinally within the aerosol-forming substrate rod 512 such that it is approximately parallel to the longitudinal axis of the aerosol-forming substrate rod 512. As shown in the drawing in Figure 5, the susceptor element 580 is positioned at a radially central location within the rod and extends along the longitudinal axis of the rod 12.

[0307] 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.

[0308] In the embodiment of FIG. 5, 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.

[0309] The aerosol-generating article 510 of Figure 5 may be used with the aerosol-generating device 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 particles include a suitable susceptor material for inductive heating.

[0310] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are understood to be modified in all instances by the term "about." Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A±10%. Within this context, the number A may be considered to include a numerical value that is within the typical standard error for the measurement of the property that the number A modifies. The number A may deviate by the percentages recited above, in some cases as used in the appended claims, provided that the amount by which A deviates does not materially affect the basic and novel property(ies) 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 an aerosol-forming material and 0.1 to 15 weight percent of carbon particles, wherein the carbon particles have a volume median particle diameter of greater than 10 micrometers, the carbon particles have a particle size distribution having a D10 particle diameter and a D90 particle diameter, and the D90 particle diameter is less than 20 times the D10 particle diameter.

2. The aerosol-forming substrate according to claim 1, wherein the carbon particles consist of one or more of graphite particles, expanded graphite particles, and graphene particles.

3. The aerosol-forming substrate according to claim 1, wherein the aerosol-forming material comprises an organic material, an aerosol-forming body, and a binder.

4. The aerosol-forming substrate according to claim 1, wherein the aerosol-forming material is in one or more forms of cut filler, powder particles, granules, pellets, fragments, spaghetti, flakes, or sheets, and the carbon particles have a volume median particle diameter of 10 to 1000 micrometers.

5. The aerosol-forming substrate according to claim 1, wherein the aerosol-forming material is in the form of an assembly of sheets, and the carbon particles have a volume median particle diameter of 10 to 200 micrometers.

6. The aerosol-forming substrate according to claim 5, wherein the carbon particles have a volume median particle diameter of 30 to 150 micrometers.

7. The aerosol-forming substrate according to claim 1, wherein the aerosol-forming substrate has a thermal conductivity exceeding 0.06 W / mK in at least one direction.

8. The aerosol-forming substrate according to claim 1, wherein the aerosol-forming substrate has a density of less than 1000 kg / m 3 3.

9. The aerosol-forming substrate according to claim 1, wherein the carbon particles consist of one or both of expanded graphite particles and graphene particles.

10. The aerosol-forming substrate according to claim 1, wherein the carbon particles have a volume median particle diameter of 10 to 75 micrometers.

11. The aerosol-forming substrate according to claim 1, wherein one or both of the volume median particle diameter and the D50 particle diameter of the carbon particles is 150 micrometers or more.

12. A method of forming an aerosol-forming substrate according to any one of claims 1 to 11, Forming a slurry comprising an organic material and carbon particles having a volume average particle diameter greater than 10 micrometers and a particle size distribution having D10 and D90 particle diameters, wherein the D90 particle diameter is less than 20 times the D10 particle diameter. Homogenizing the slurry. Casting and drying the slurry to form the aerosol-forming substrate. A method comprising.

13. A method of forming an aerosol-forming substrate according to any one of claims 1 to 11, Providing an aerosol-forming material, Coating carbon particles having a volume average particle diameter greater than 10 micrometers onto the aerosol-forming material to form the aerosol-forming substrate. A method comprising.

14. An aerosol-generating article comprising the aerosol-forming substrate according to any one of claims 1 to 11.

15. An aerosol-generating system comprising the aerosol-generating article according to claim 14 and an electric aerosol-generating device configured to heat the aerosol-generating article to generate an aerosol.

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