Aerosol-generating article comprising a hollow tubular substrate element - Patents.com

Abstract

The aerosol-generating article (10)(110) comprises an aerosol-generating substrate (12) comprising a hollow tubular substrate element (40)(140) having a multi-layered peripheral wall (42) defining a longitudinal airflow channel (44)(144), the peripheral wall (42) being formed from a plurality of overlapping layers of homogenized tobacco material, the longitudinal airflow channel (44)(144) having a diameter of at least 3 millimeters, and a downstream section (14) provided downstream of the aerosol-generating substrate (12).

Description

[Technical field]

[0001] The present invention relates to an aerosol-generating article comprising an aerosol-generating substrate adapted to generate an inhalable aerosol upon heating. [Background technology]

[0002] Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than burned, are well known in the art. Typically, in such heated smoking articles, aerosol is generated by transferring heat from a heat source to a physically separated aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0003] Numerous prior art documents disclose aerosol generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol generating devices, in which the aerosol is generated by heat transfer from one or more electric heater elements of the aerosol generating device to an aerosol-generating substrate of the heated aerosol-generating article. For example, an electrically heated aerosol generating device has been proposed, which comprises an internal heater blade adapted to be inserted into the aerosol-generating substrate. It is also known to use an aerosol-generating article in combination with an external heating system. For example, International Application No. WO-A-2020 / 115151 describes the provision of one or more heating elements arranged around the periphery of the aerosol-generating article when the aerosol-generating article is received in a cavity of the aerosol-generating device. Alternatively, an inductively heated aerosol-generating article is proposed by International Application No. WO-A-2015 / 176898, which comprises an aerosol-generating substrate and a susceptor disposed within the aerosol-generating substrate.

[0004] In general, it can be difficult to provide efficient heating of the aerosol-generating substrate throughout the rod of substrate. The portion of the substrate closest to the heating element will necessarily be heated most effectively, while incomplete heat transfer through the substrate means that the portion of the substrate furthest from the heating element may not be heated effectively. Thus, aerosol generation from those portions of the substrate that are not effectively heated will not be optimal, and in some cases, the portions of the substrate may never reach a high enough temperature to generate aerosol during use. For example, if an external heating element is used to heat the rod of the aerosol-generating substrate as described above, the central portion of the rod of the aerosol-generating substrate is not likely to generate as much aerosol as the outer portions of the rod, and in some cases may not generate any aerosol at all. Thus, overall, aerosol generation from the aerosol-generating rod may be inefficient, and portions of the aerosol-generating substrate are potentially wasted.

[0005] It would therefore be desirable to provide an aerosol-generating article having an aerosol-generating substrate adapted to provide more efficient aerosolization of the aerosol-generating substrate and reduce waste of substrate material, such as tobacco. It would be particularly desirable to provide such an article with a relatively simple design so that it could be manufactured in a cost-effective manner and incorporated into existing product designs. It would further be desirable to provide such an article that could be easily adapted so that it could be heated with various types of heating devices, including induction heating devices and resistance heating devices. Summary of the Invention

[0006] The present disclosure relates to an aerosol-generating article. The aerosol-generating article may comprise an aerosol-generating substrate comprising a hollow tubular substrate element. The hollow tubular substrate element may have a multi-layered peripheral wall defining a longitudinal airflow channel. The peripheral wall may be formed of multiple overlapping layers of homogenized tobacco material. The longitudinal airflow channel may have a diameter of at least 3 millimeters. The aerosol-generating article may further comprise a downstream section disposed downstream of the aerosol-generating substrate.

[0007] According to the present invention, there is provided an aerosol-generating article comprising an aerosol-generating substrate comprising a hollow tubular substrate element having a multi-layered peripheral wall defining a longitudinal airflow channel, the peripheral wall being formed from a plurality of overlapping layers of homogenized tobacco material, the longitudinal airflow channel having a diameter of at least 3 millimeters, and a downstream section provided downstream of the aerosol-generating substrate.

[0008] The term "aerosol-generating article" as used herein refers to a heated article for producing an aerosol, the article comprising an aerosol-generating substrate suitable and intended to be heated or combusted to release volatile compounds capable of forming an aerosol. Such articles are commonly referred to as non-combustion heated articles. A conventional cigarette is ignited when a user applies a flame to one end of the cigarette and draws air through the other end. The localized heat provided by the flame and the oxygen in the air drawn through the cigarette ignites the end of the cigarette, and the resulting combustion produces inhalable smoke. In contrast, in a "heated aerosol-generating article", the aerosol is generated by heating the aerosol-generating substrate, rather than by combustion of the aerosol-generating substrate. Known heated aerosol-generating articles include, for example, electrically heated aerosol-generating articles and aerosol-generating articles in which the aerosol is generated by the transfer of heat from a combustible fuel element or heat source to a physically separated aerosol-generating substrate.

[0009] Also known are aerosol-generating articles adapted for use in aerosol-generating systems that supply aerosol former to the aerosol-generating article, where the aerosol-generating substrate in the aerosol-generating article contains substantially less aerosol former relative to the aerosol-generating substrate that, during operation, carries and provides substantially all of the aerosol former used to form the aerosol.

[0010] The term "aerosol-generating substrate" as used herein refers to a substrate capable of releasing, upon heating, a volatile compound capable of forming an aerosol. The aerosol generated from the aerosol-generating substrate of the aerosol-generating article described herein may be visible or invisible and may include vapor (e.g., fine particles of a substance that is normally liquid or solid at room temperature in a gaseous state) as well as gas and liquid droplets of the condensed vapor.

[0011] As used herein, the term "homogenized plant material" encompasses any plant material formed by agglomeration of plant particles. For example, a sheet or web of homogenized tobacco material for an aerosol-generating substrate of the present invention may be formed by agglomerating particles of tobacco material obtained by grinding, crushing, or comminuting plant material and, optionally, one or more of tobacco lamina and tobacco stems. Homogenized plant material may be produced by casting, extrusion, a papermaking process, or any other suitable process known in the art.

[0012] As defined above, the present invention provides an aerosol-generating article having a novel aerosol-generating substrate in the form of a hollow tubular substrate element. The hollow tubular substrate element is formed of multiple overlapping layers of homogenized tobacco material that are combined to form the peripheral wall of the hollow tubular substrate element. The "peripheral" wall of the hollow tubular substrate corresponds to the main walls that define the tubular structure. Preferably, the hollow tubular substrate element is composed only of the peripheral wall. Thus, the peripheral wall contains all of the homogenized tobacco material that generates an aerosol upon heating of the aerosol-generating substrate.

[0013] The peripheral wall of the hollow tubular substrate element defines a longitudinal airflow channel, the term "longitudinal" referring to the longitudinal axis of the aerosol-generating article. The longitudinal airflow channel has a diameter of at least about 3 millimeters. The longitudinal airflow channel is preferably substantially empty such that there is nothing within the channel that could potentially impede the flow of air and aerosol through the hollow tubular substrate element. In particular, the longitudinal airflow channel is substantially free of tobacco material.

[0014] By providing an aerosol-generating substrate in a tubular form, the amount of tobacco material in the aerosol-generating substrate can be advantageously optimized, so that an aerosol can be efficiently generated from the aerosol-generating substrate upon heating. Furthermore, the tubular form eliminates a central portion of the homogenized tobacco material that may not be heated as effectively as the outer portion, particularly in an aerosol-generating device equipped with an external heating means. Overall, therefore, the amount of tobacco material can be significantly reduced compared to a conventional solid plug of homogenized tobacco material, reducing tobacco waste. For example, it has been found that the amount of tobacco material used in the hollow tubular substrate element of the aerosol-generating article according to the present invention can be reduced by up to 40 percent compared to the amount of tobacco material used in a solid plug of a substrate of a conventional aerosol-generating article, while still maintaining a similar delivery of aerosol to the consumer.

[0015] The amount of tobacco material provided within the substrate can be easily adapted by controlling the parameters of the hollow tubular substrate element, such as the peripheral wall density and wall thickness. In this way, it is possible to adapt the hollow tubular substrate element so that it matches the heating zone of the associated aerosol-generating device. Thus, the proportion of the aerosol-generating substrate that can be heated to the temperature required for aerosol generation is maximized so that aerosol generation from the aerosol-generating substrate is optimized.

[0016] The hollow tubular substrate element is formed by a plurality of overlapping layers of homogenized tobacco material. The plurality of overlapping layers of homogenized tobacco material are preferably directly overlaid on one another such that adjacent layers are in direct contact with one another without an intermediate layer. The plurality of overlapping layers of homogenized tobacco material may advantageously be arranged to define a plurality of voids between adjacent layers. As a result, the peripheral wall typically has a porous structure. As described in more detail below, the voids defined between adjacent layers of homogenized tobacco material may advantageously provide both transverse and longitudinal porosity such that aerosol generated upon heating of the aerosol-generating substrate is effectively released into the longitudinal airflow channel and flows through the channel mixed with external air, the aerosol being drawn through the article upon puffing by the consumer.

[0017] The multi-layer arrangement of layers further provides a relatively dense structure with sufficient structural rigidity to provide an aerosol-generating substrate within an aerosol-generating article without the need for any additional support, such as a carrier layer or internal support members within the longitudinal airflow channels.

[0018] Providing a longitudinal airflow channel having a diameter of at least about 3 millimeters also advantageously provides greater control of airflow management through the aerosol-generating article.

[0019] The hollow tubular substrate element has a relatively simple structure that can be manufactured in a simple and cost-effective manner using existing equipment, and can then be incorporated into an aerosol-generating article with other components using known assembly methods and equipment.

[0020] Advantageously, if desired, the hollow tubular substrate element may be incorporated directly into the aerosol-generating article without an outer wrapper, providing a distinctive appearance and texture to the outer surface of the aerosol-generating substrate.

[0021] As noted above, the hollow tubular substrate element forming the aerosol-generating substrate of the aerosol-generating article according to the present invention is formed from a plurality of overlapping layers of homogenized tobacco material, the layers overlapping each other in the transverse direction to provide a multi-layer structure.

[0022] Preferably, the hollow tubular substrate element comprises at least about two overlapping layers of homogenized tobacco material, and more preferably, at least about three overlapping layers of homogenized tobacco material.

[0023] The hollow tubular substrate element preferably comprises up to about 10 overlapping layers of homogenized tobacco material, more preferably up to about 5 overlapping layers of homogenized tobacco material. For example, the hollow tubular substrate element may comprise from about 2 to about 10 overlapping layers of homogenized tobacco material, or from about 3 to about 5 overlapping layers of homogenized tobacco material.

[0024] As mentioned above, the peripheral wall of the hollow tubular substrate element preferably has a porous structure as a result of voids formed between overlapping layers of homogenized tobacco material. The peripheral wall is preferably porous in both the transverse and longitudinal directions.

[0025] The peripheral wall of the hollow tubular substrate element preferably has a cross-sectional porosity of at least about 0.3, more preferably at least about 0.35, and most preferably at least about 0.4.

[0026] Preferably, the peripheral wall has a cross-sectional porosity of at most about 0.7, more preferably at most about 0.65, and most preferably at most about 0.6.

[0027] For example, the cross-sectional porosity of the peripheral wall can be from about 0.3 to about 0.7, or from about 0.35 to about 0.65, or from about 0.4 to about 0.6.

[0028] The term "porosity" as used herein refers to the proportion of void space within a permeable or porous body. Specifically, in the context of the present invention, the term "cross-sectional porosity" refers to the proportion of void space in the cross-sectional area of ​​the peripheral wall of a hollow tubular substrate element. The cross-sectional porosity is the area fraction of void space in the transverse cross-sectional area of ​​the peripheral wall. The transverse cross-sectional area of ​​the peripheral wall is the area of ​​the peripheral wall in a plane perpendicular to the longitudinal axis of the hollow tubular substrate element.

[0029] The cross-sectional porosity of the peripheral wall allows aerosol to pass laterally through the peripheral wall such that it can be drawn into and through the longitudinal airflow channel.

[0030] Further details regarding the measurement of cross-sectional porosity within a porous or air-permeable body can be found in the publication of International Patent Application No. WO-A-2016 / 023965 in the name of the Applicant.

[0031] Advantageously, the cross-sectional porosity may be determined using a digital image processing process. An image of a cross-section of a hollow tubular substrate may be acquired and a threshold applied to distinguish pixels representing the aerosol-forming substrate from pixels representing voids. The cross-sectional porosity is calculated according to the following formula: P o =N void / N tot . In the formula, P o is the overall porosity of the cross section, and N void is the number of pixels representing voids in the cross section, and N tot is the total number of pixels in the transverse section.

[0032] It is noted that acquisition of digital images may be performed by any suitable method, for example, by using a digital camera or computed tomography. Images may be represented in full RGB (red-green-blue) color, grayscale, or binary (black and white) in any suitable image format. A uniform background is preferred in any image to facilitate background detection and removal during image processing. Image resolution must be high enough to accurately resolve the morphology of the hollow tubular substrate.

[0033] Preferably, the peripheral wall of the hollow tubular substrate element has a density of at least about 200 milligrams per cubic centimeter, more preferably at least about 300 milligrams per cubic centimeter, more preferably at least about 400 milligrams per cubic centimeter, more preferably at least about 500 milligrams per cubic centimeter, more preferably at least about 600 milligrams per cubic centimeter, more preferably at least about 700 milligrams per cubic centimeter, more preferably at least about 800 milligrams per cubic centimeter.

[0034] The peripheral wall of the hollow tubular substrate element preferably has a density of less than about 1 gram per cubic centimeter.

[0035] In the context of the present invention, "density" refers to the bulk density of the peripheral wall, including overlapping layers, rather than the density of the individual layers. A relatively high density of the peripheral wall maximizes the amount of tobacco material that can be provided for a given length of the aerosol-generating substrate, and therefore the amount of aerosol generated from the hollow tubular substrate element.

[0036] Preferably, the peripheral wall provides at least about 150 milligrams of homogenized tobacco material per centimeter of length of the hollow tubular substrate, more preferably at least about 200 milligrams of homogenized tobacco material per centimeter of length, more preferably at least about 300 milligrams of homogenized tobacco material per centimeter of length, more preferably at least about 400 milligrams of homogenized tobacco material per centimeter of length, more preferably at least about 500 milligrams of homogenized tobacco material per centimeter of length, more preferably at least about 600 milligrams of homogenized tobacco material per centimeter of length, more preferably at least about 700 milligrams of homogenized tobacco material per centimeter of length, more preferably at least about 800 milligrams of homogenized tobacco material per centimeter of length, based on measurements taken at 22.5 degrees Celsius and 60 percent humidity.

[0037] Preferably, the hollow tubular substrate element has a longitudinal tensile strength of between 11 kNewtons / meter and 14 kNewtons / meter, measured according to TAPPI test method T494 om-01 2006.

[0038] Preferably, the axial compressive strength of the hollow tubular substrate element is between 7 MPa and 9 MPa, measured according to the test method described in ASTM D695-15 (2018).

[0039] Preferably, the radial compressive strength of the hollow tubular substrate element, measured according to the test method described in ASTM D2412-11 (2018), is between 7 MPa and 9 MPa.

[0040] The hollow tubular substrate element preferably has a length of at least about 10 millimeters, more preferably at least about 12 millimeters, more preferably at least about 15 millimeters.

[0041] The hollow tubular substrate element preferably has a length of up to about 40 millimeters, more preferably up to about 37 millimeters, more preferably up to about 35 millimeters.

[0042] For example, the hollow tubular substrate element can have a length of from about 10 millimeters to about 40 millimeters, or from about 12 millimeters to about 37 millimeters, or from about 15 millimeters to about 35 millimeters.

[0043] As mentioned above, the length of the hollow tubular substrate element may advantageously be matched to the longitudinal dimension of a heating element in a corresponding aerosol-generating device used to heat the aerosol-generating article, In this way, as much of the aerosol-generating substrate as possible may be heated during use in order to optimize the amount of aerosol that can be produced and reduce the amount of tobacco waste.

[0044] Preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be at least about 0.15. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be at least about 0.25. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be at least about 0.4.

[0045] Preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be up to about 0.6. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be up to about 0.55. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be up to about 0.5.

[0046] For example, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article substrate may be from about 0.15 to about 0.6, more preferably from about 0.25 to about 0.55, more preferably from about 0.4 to about 0.5.

[0047] Preferably, the hollow tubular substrate element has an outer diameter of at least about 4 millimeters, more preferably at least about 4.25 millimeters, and more preferably at least about 4.5 millimeters.

[0048] Preferably, the hollow tubular substrate element has an outer diameter of at most about 9 millimeters, more preferably at most about 8 millimeters, more preferably at most about 7.5 millimeters.

[0049] For example, the hollow tubular substrate element may have an outer diameter of from about 4 millimeters to about 9 millimeters, or from about 4.25 millimeters to about 8 millimeters, or from about 4.5 millimeters to about 7.5 millimeters.

[0050] Preferably, the outer diameter of the hollow tubular substrate element is substantially the same as the outer diameter of the aerosol-generating article.

[0051] As mentioned above, the hollow tubular substrate element provides a longitudinal airflow channel defined by a peripheral wall. The longitudinal airflow channel extends between opposite ends of the hollow tubular substrate element and is preferably open at both the upstream and downstream ends. The open upstream end provides the primary air inlet for drawing air through the aerosol-generating article when a consumer puffs on the article. The longitudinal airflow channel thus provides the primary passageway for the flow of air and aerosol through the article.

[0052] Preferably, the hollow tubular substrate element provides an unrestricted flow channel, which means that the hollow tubular substrate element provides a negligible level of resistance to withdrawal (RTD). The term "negligible level of RTD" is used to describe an RTD of less than 1 mmH2O per 10 mm of the length of the hollow tubular element, preferably less than 0.4 mmH2O per 10 mm of the length of the hollow tubular element, more preferably less than 0.1 mmH2O per 10 mm of the length of the hollow tubular element.

[0053] The longitudinal airflow channels have a diameter of at least 3 millimeters, which corresponds to the inner diameter of the hollow tubular substrate element. Preferably, the longitudinal airflow channels have a diameter of at least about 3.25 millimeters, and more preferably, a diameter of at least about 3.5 millimeters.

[0054] Preferably, the longitudinal airflow channel has a diameter of up to about 7 millimeters, more preferably, a diameter of up to about 6 millimeters, more preferably, a diameter of up to about 5.5 millimeters.

[0055] For example, the longitudinal airflow channel may have a diameter of about 3 millimeters to about 7 millimeters, or about 3.25 millimeters to about 6 millimeters, or about 3.5 millimeters to about 5.5 millimeters.

[0056] Providing an airflow channel with a minimum diameter of 3 millimeters allows the channel volume to be large enough to provide the desired level of airflow while still maintaining sufficient wall thickness, which is necessary for the specification to provide a sufficient amount of tobacco material within the hollow tubular substrate element and have sufficient rigidity so that the hollow tubular substrate element can be self-supporting.

[0057] The longitudinal airflow channels may have a constant diameter along the length of the hollow tubular substrate element. However, the diameter of the longitudinal airflow channels may vary along the length of the hollow tubular substrate element.

[0058] The longitudinal airflow channels preferably have a substantially circular transverse cross-section. Alternatively, the longitudinal airflow channels may have a substantially elliptical transverse cross-section.

[0059] Preferably, the ratio of the inner diameter to the outer diameter of the hollow tubular substrate element is at least about 0.4, more preferably at least about 0.45, more preferably at least about 0.5.

[0060] Preferably, the outer diameter of the hollow tubular substrate element and the diameter of the longitudinal airflow channel are adapted to provide a desired wall thickness for the peripheral wall. Preferably, the peripheral wall has a wall thickness of at least about 1 millimeter, more preferably at least about 1.25 millimeters, and more preferably at least about 1.5 millimeters.

[0061] Preferably, the peripheral wall has a wall thickness of up to about 2.25 millimeters, more preferably up to about 2 millimeters, more preferably up to about 1.8 millimeters.

[0062] For example, the peripheral wall may have a thickness of from about 1 millimeter to about 2.25 millimeters, or from about 1.25 millimeters to about 2 millimeters, or from about 1.5 millimeters to about 1.8 millimeters.

[0063] The overlapping layers of homogenized tobacco material may be arranged in any suitable manner to provide the desired wall thickness and porosity for the peripheral wall. Each layer of homogenized tobacco material typically extends at least once around the hollow tubular substrate element, and preferably each layer of homogenized tobacco material extends multiple times around the hollow tubular substrate element to build up the peripheral wall structure.

[0064] Preferably, multiple layers of homogenized tobacco material are helically wound around the longitudinal axis of the hollow tubular substrate element, providing a helically wound structure similar to the layered structure of a conventional paper string. Hollow tubular substrate elements incorporating a helical arrangement of layers for use in the present invention can be manufactured using existing straw making equipment, such as the Hauni Straw Maker (HSM) from Hauni Maschinenbau GmbH.

[0065] The use of a spirally wound structure provides optimal structural strength to the hollow tubular substrate element, increasing mechanical strength in all directions compared to a similar structure with a simple longitudinal wrapping. Furthermore, the spirally wound arrangement provides a denser homogenized tobacco material at the periphery. The manufacturing method used to create the spiral arrangement of layers also provides greater control over the dimensions of the hollow tubular substrate element, such that variations in the outer and inner diameters are minimized. This provides greater consistency between products.

[0066] The hollow tubular substrate element may optionally include an adhesive to seal adjacent layers together. Suitable adhesives will be known to those skilled in the art. Preferably, the adhesive is a water-based adhesive, such as a water-based starch adhesive or a polyvinyl alcohol (PVOH) adhesive.

[0067] In certain embodiments of the present invention, the aerosol-generating substrate may further comprise a sealing element at the upstream end of the hollow tubular substrate element, which covers the upstream end of the hollow tubular substrate element. In such embodiments, the open upstream end of the hollow tubular substrate element is thus covered and sealed by the sealing element, so that air is not drawn into the longitudinal airflow channel. The sealing element must therefore be adapted to be removable or pierceable prior to use in order to open the upstream end of the hollow tubular substrate element and admit air into the longitudinal airflow channel.

[0068] The peripheral wall of the hollow tubular substrate element formed of overlapping layers of homogenized tobacco material is preferably at least partially exposed on the outer surface of the hollow tubular substrate element. The hollow tubular substrate element is therefore preferably not wrapped along at least a portion of its length. The outer surface of the peripheral wall should provide an acceptable surface for forming the exterior of the aerosol-generating article, and the layered structure may provide a distinctive appearance and texture.

[0069] Alternatively, the hollow tubular substrate element may be covered with at least one wrapper. For example, the hollow tubular substrate element may be covered with a conventional paper wrapper. The hollow tubular substrate element may be covered with a tobacco-containing wrapper, such as a tobacco paper wrapper.

[0070] The hollow tubular substrate element is formed of multiple layers of homogenized tobacco material, which is preferably in the form of a sheet. As used herein with respect to the present invention, the term "sheet" refers to a laminar element having a width and length that is significantly greater than its thickness.

[0071] The sheets may each individually have a thickness of from 100 micrometers to 600 micrometers, preferably from 150 micrometers to 300 micrometers, and most preferably from 200 micrometers to 250 micrometers.

[0072] The homogenized tobacco material comprises tobacco particles. A sheet of homogenized tobacco material for use in the present invention has a tobacco content of at least about 40 weight percent on a dry weight basis, more preferably at least about 50 weight percent on a dry weight basis, more preferably at least about 70 weight percent on a dry weight basis, and most preferably at least about 90 weight percent on a dry weight basis.

[0073] In the context of the present invention, the term "tobacco particles" refers to particles of any plant component of the Nicotiana species. The term "tobacco particles" encompasses ground or powdered tobacco lamina, ground or powdered tobacco stems, tobacco dust, tobacco fines, and other particulate tobacco by-products formed during tobacco processing, handling, and shipping. In a preferred embodiment, the tobacco particles are substantially entirely derived from tobacco lamina. In contrast, isolated nicotine and nicotine salts are compounds derived from tobacco, but for purposes of the present invention, they are not considered tobacco particles and are not included in the percentage of particulate plant material.

[0074] The homogenized tobacco material may further include one or more aerosol formers. Upon volatilization, the aerosol formers may carry other vaporized compounds released from the aerosol-generating substrate upon heating, such as nicotine and flavorants in the aerosol. Aerosol formers suitable for inclusion in the homogenized plant material are known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, propylene glycol, 1,3-butanediol, and glycerol), esters of polyhydric alcohols (such as glycerol mono-, di-, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and tetradecanedioate).

[0075] The homogenized tobacco material may have an aerosol former content of about 5 weight percent to about 30 weight percent on a dry weight basis (such as about 10 weight percent to about 25 weight percent on a dry weight basis, or about 15 weight percent to about 20 weight percent on a dry weight basis). The aerosol former may act as a humectant in the homogenized tobacco material.

[0076] The two or more overlapping layers of homogenized tobacco material forming the peripheral wall of the hollow tubular substrate element may all be formed of the same homogenized tobacco material. Alternatively, the peripheral wall includes one or more layers of a first homogenized tobacco material and one or more layers of one or more second homogenized tobacco materials different from the first homogenized tobacco material. The peripheral wall is thus formed from a combination of at least two different homogenized tobacco materials. The first homogenized tobacco material and the second homogenized tobacco material may differ from each other in composition. For example, the first and second homogenized tobacco materials may have different tobacco contents, or different aerosol former contents, or both, from each other. Alternatively, or additionally, the first and second homogenized tobacco materials may be provided with different levels of flavorants to provide a flavor profile. Alternatively, or additionally, the first homogenized tobacco material and the second homogenized tobacco material may differ from each other in one or more physical parameters, including but not limited to density, porosity, or thickness.

[0077] The use of different homogenized tobacco materials within the hollow tubular substrate element provides greater flexibility for the delivery of aerosol upon heating. For example, the compositions of the first and second homogenized tobacco materials can be tailored to provide for the delivery of aerosol at different times or rates. The use of different homogenized tobacco materials can also provide improved stability, for example, by avoiding the combination of potentially incompatible components.

[0078] Preferably, the multiple layers of homogenized tobacco material include one or more sheets of cast leaves.

[0079] Preferably, the cast leaf has a porosity at 25 degrees Celsius of about 20 to about 60 percent, more preferably about 30 to about 50 percent, and more preferably about 35 to about 45 percent.

[0080] Alternatively, or in addition to the one or more sheets of cast leaf, the multiple layers of homogenized tobacco material may include one or more layers of cigarillo paper.

[0081] Preferably, the cigarillo paper has a porosity at 25 degrees Celsius of about 30 percent to about 80 percent, more preferably about 40 percent to about 70 percent, and more preferably about 50 percent to about 60 percent.

[0082] The peripheral wall may be formed of alternating layers of cast leaf and cigarillo paper.

[0083] The hollow tubular substrate element of the aerosol-generating article according to the invention preferably comprises one or more susceptor elements positioned in contact with the circumferential wall for inductive heating of the homogenised plant material during use.

[0084] The term "susceptor element" as used herein refers to an element that includes a material capable of converting electromagnetic energy into heat. When the susceptor element is located in an alternating electromagnetic field, the susceptor heats up. Heating of the susceptor element can be the result of at least one of hysteresis losses and eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material.

[0085] The susceptor element may be arranged such that when an aerosol-generating article is received within the cavity of the aerosol generating device, the oscillating electromagnetic field generated by the inductor coil induces a current in the susceptor element, heating the susceptor element. In these embodiments, the aerosol generating device is preferably capable of generating a fluctuating electromagnetic field having a magnetic field strength (H field strength) of 1 to 5 kiloamperes per meter (kA / m), preferably 2 to 3 kA / m, e.g., about 2.5 kA / m. The electrically operated aerosol generating device is preferably capable of generating a fluctuating electromagnetic field having a frequency of 1 to 30 MHz, e.g., 1 to 10 MHz, e.g., 5 to 7 MHz.

[0086] The susceptor elements may comprise any suitable material. The susceptor elements may be formed from any material that can be inductively heated to a temperature sufficient to release volatile compounds from the aerosol-generating substrate. Suitable materials for the elongated susceptor elements include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Some susceptor elements comprise metal or carbon. Advantageously, the susceptor elements may comprise or consist of ferromagnetic materials, such as ferritic iron, ferromagnetic steel or stainless steel, ferromagnetic alloys, ferromagnetic particles, and ferrites. Suitable susceptor elements may be or include aluminum. The susceptor elements preferably comprise more than about 5 percent, preferably more than about 20 percent, more preferably more than about 50 percent or more than about 90 percent ferromagnetic or paramagnetic materials. Some elongated susceptor elements may be heated to temperatures greater than about 250 degrees Celsius.

[0087] The susceptor element may comprise a non-metallic core having a metallic layer disposed thereon. For example, the susceptor element may include a ceramic core or a metallic track formed on the outer surface of the substrate.

[0088] The hollow tubular substrate element preferably comprises one or more susceptor elements on the surface of the peripheral wall. The hollow tubular substrate element may comprise one or more susceptor elements on the inner surface of the peripheral wall within the longitudinal airflow channel. Alternatively, or additionally, the hollow tubular substrate element may comprise one or more susceptor elements on the outer surface of the peripheral wall.

[0089] The hollow tubular substrate element preferably comprises a tubular susceptor element mounted on at least one surface of the peripheral wall. The tubular susceptor element may be mounted on the inner surface of the peripheral wall for heating the hollow tubular substrate element from the inside. Alternatively, the tubular susceptor element may be mounted on the outer surface of the hollow tubular substrate element for heating the hollow tubular substrate element from the outside.

[0090] The use of a tubular susceptor element advantageously optimizes heating of the homogenized tobacco material within the peripheral wall since the susceptor element contacts a relatively large surface area of ​​the homogenized tobacco material. Due to the tubular form of the hollow tubular substrate element, the thickness of the substrate is relatively small, resulting in efficient heat transfer through the peripheral wall from the side where the tubular susceptor element is located.

[0091] As defined above, in the aerosol-generating article of the present invention, the aerosol-generating substrate formed of a hollow tubular substrate element is combined with a downstream section located downstream of the aerosol-generating substrate. The downstream section is preferably located immediately downstream of the aerosol-generating substrate. The downstream section of the aerosol-generating article preferably extends between the aerosol-generating substrate and the downstream end of the aerosol-generating article. The downstream section may comprise one or more elements, each of which is described in more detail within the present disclosure.

[0092] The downstream section preferably comprises at least one hollow tubular element, which may be located immediately downstream of the aerosol-generating substrate, in other words, the hollow tubular element may abut the downstream end of the aerosol-generating substrate, such that the flow of aerosol from the longitudinal airflow channel of the hollow tubular substrate element into the downstream section and through the aerosol-generating article is optimized.

[0093] The downstream section of the aerosol-generating article preferably comprises a single hollow tubular element, in other words the downstream section of the aerosol-generating article may comprise only one hollow tubular element.

[0094] The term "hollow tubular element" as used throughout this disclosure generally refers to an elongated element that defines a lumen or airflow passage along its longitudinal axis. In particular, the term "tubular" is used hereinafter with reference to a tubular element that has a substantially cylindrical cross-section and defines at least one airflow conduit that establishes uninterrupted fluid communication between the upstream end of the tubular element and the downstream end of the tubular element. However, it will be appreciated that alternative shapes (e.g. alternative cross-sectional shapes) of the tubular element may be possible. The hollow tubular element may be an individual, separate element of the aerosol-generating article, having a defined length and thickness.

[0095] In the context of the present invention, the hollow tubular element of the downstream section provides an unrestricted flow channel through the airflow passage. This means that the hollow tubular element provides a negligible level of resistance to drawing (RTD), as defined above. Thus, the airflow passage should not include any components that would impede the longitudinal air flow. Preferably, the airflow passage is substantially empty.

[0096] The hollow tubular element in the downstream section provides an empty cavity downstream of the aerosol-generating substrate, which improves cooling and nucleation of the aerosol particles generated by the aerosol-generating substrate, and therefore acts as an aerosol cooling element.

[0097] The length of the hollow tubular element may be at least about 12 mm. The length of the hollow tubular element may be at least about 15 mm. The length of the hollow tubular element may be at least about 20 mm.

[0098] The length of the hollow tubular element in the downstream section may be about 50 mm or less. The length of the hollow tubular element may be about 45 mm or less. The length of the hollow tubular element may be about 40 mm or less.

[0099] For example, the length of the hollow tubular element in the downstream section may be about 12 mm to 50 mm. The length of the hollow tubular element may be about 15 mm to 45 mm. The length of the hollow tubular element may be about 20 mm to about 40 mm. The length of the hollow tubular element may be about 30 mm.

[0100] The relatively long hollow tubular element provides and defines a relatively long internal cavity within the downstream section of the aerosol-generating article. By providing a relatively long cavity, the nucleation benefits discussed above are maximized, thereby improving aerosol formation and cooling.

[0101] The ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section may be about 1.25 or less. Preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section may be about 1 or less. More preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section may be about 0.75 or less.

[0102] The ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section may be at least about 0.25. Preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section may be at least about 0.30. More preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section may be at least about 0.40.

[0103] For example, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section may be from about 0.25 to about 1.25, or from about 0.3 to about 1, or from about 0.4 to about 0.75.

[0104] The ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section may be about 1 or less. Preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section may be about 0.90 or less. More preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section may be about 0.85 or less.

[0105] The ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section may be at least about 0.35. Preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section may be at least about 0.45. More preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section may be at least about 0.50.

[0106] For example, the ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section may be from about 0.35 to about 1, or from about 0.45 to about 0.9, or from about 0.5 to about 0.85.

[0107] The ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article may be about 0.80 or less. Preferably, the ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article may be about 0.70 or less. More preferably, the ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article may be about 0.60 or less.

[0108] The ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article may be at least about 0.25. Preferably, the ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article may be at least about 0.30. More preferably, the ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article may be at least about 0.40.

[0109] For example, the ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article may be from about 0.25 to about 0.8, or from about 0.3 to about 0.7, or from about 0.4 to about 0.6.

[0110] The wall thickness of the hollow tubular element in the downstream section may be at least about 100 micrometers. The wall thickness of the hollow tubular element in the downstream section may be at least about 150 micrometers. The wall thickness of the hollow tubular element in the downstream section may be at least about 200 micrometers, preferably at least about 250 micrometers, and even more preferably at least about 500 micrometers (or 0.5 mm).

[0111] The wall thickness of the hollow tubular element in the downstream section may be about 2 millimeters or less, preferably about 1.5 millimeters or less, and even more preferably about 1.25 mm or less. The wall thickness of the hollow tubular element in the downstream section may be about 1 millimeter or less. The wall thickness of the hollow tubular element in the downstream section may be about 500 micrometers or less.

[0112] The wall thickness of the hollow tubular element in the downstream section can be from about 100 micrometers to about 2 millimeters, preferably from about 150 micrometers to about 1.5 millimeters, and even more preferably from about 200 micrometers to about 1.25 millimeters.

[0113] Keeping the wall thickness of the hollow tubular element in the downstream section relatively small ensures that the overall internal volume of the hollow tubular element (which is made available for the aerosol to initiate the nucleation process as soon as the aerosol components leave the aerosol-generating substrate) and the cross-sectional surface area of ​​the longitudinal airflow channel of the hollow tubular element are effectively maximized, while at the same time ensuring that the hollow tubular element has the necessary structural strength to provide some support to the rod of the aerosol-generating substrate as well as to prevent the collapse of the aerosol-generating article, and that the RTD of the hollow tubular element is minimized. It is understood that a larger value of the cross-sectional surface area of ​​the cavity of the hollow tubular element is associated with a reduced speed of the aerosol flow along the aerosol-generating article, which is also expected to favor the nucleation of the aerosol. Furthermore, it may be expected that by utilizing a hollow tubular element with a relatively small thickness, it is possible to substantially prevent the diffusion of the ventilation air before it contacts and mixes with the aerosol flow, which is also understood to be more favorable for the nucleation phenomenon. Indeed, by providing more controllably localized cooling of the stream of volatilized species, it is possible to enhance the cooling effect on the formation of new aerosol particles.

[0114] The hollow tubular element in the downstream section preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating substrate and the outer diameter of the aerosol-generating article.

[0115] The hollow tubular element may have an outer diameter of 5 millimeters to 12 millimeters, for example 5 millimeters to 10 millimeters, or 6 millimeters to 8 millimeters. Preferably, the hollow tubular element has an outer diameter of 7.2 millimeters ±10 percent.

[0116] The hollow tubular element in the downstream section may have a constant inner diameter along the length of the hollow tubular element. However, the inner diameter of the hollow tubular element may vary along the length of the hollow tubular element.

[0117] The hollow tubular element of the downstream section may have an inner diameter of at least about 2 millimeters. For example, the hollow tubular element may have an inner diameter of at least about 2.5 millimeters, at least about 3 millimeters, or at least about 3.5 millimeters. Providing a hollow tubular element with an inner diameter as presented above may advantageously provide the hollow tubular element with sufficient stiffness and strength.

[0118] The hollow tubular element of the downstream section may have an inner diameter of about 10 millimeters or less. For example, the hollow tubular element may have an inner diameter of about 9 millimeters or less, about 8 millimeters or less, or about 7.5 millimeters or less. Providing a hollow tubular element with an inner diameter as set forth above may advantageously reduce the resistance to withdrawal of the hollow tubular element.

[0119] For example, the hollow tubular element of the downstream section can have an inner diameter of about 2 millimeters to about 10 millimeters, about 2.5 millimeters to about 9 millimeters, about 3 millimeters to about 8 millimeters, or about 3.5 millimeters to about 7.5 millimeters.

[0120] The ratio of the inner diameter of the hollow tubular substrate element to the inner diameter of the hollow tubular element in the downstream section is preferably from about 0.8 to about 1.2, more preferably from about 0.9 to about 1.1, and most preferably about 1.

[0121] Particularly preferably, the inner diameter of the hollow tubular substrate element is substantially equal to the inner diameter of the hollow tubular element of the downstream section.

[0122] The hollow tubular element of the downstream section may comprise a paper-based material. The hollow tubular element may comprise at least one layer of paper. The paper may be a very stiff paper. The paper may be a crimped paper, such as crimped heat-resistant paper or crimped parchment paper.

[0123] Preferably, the hollow tubular element may comprise cardboard. The hollow tubular element may be a cardboard tube. The hollow tubular element may be formed from cardboard. Advantageously, cardboard is a cost-effective material that offers a balance between being deformable to provide ease of insertion of the article into the aerosol generating device and being sufficiently rigid to provide proper engagement of the article with the interior of the device. Thus, a cardboard tube may offer suitable resistance to deformation or compression during use.

[0124] The hollow tubular element may be a paper tube. The hollow tubular element may be a tube formed from spirally wound paper. The hollow tubular element may be formed from multiple layers of paper. The paper may have a basis weight of about 50 grams per square meter, at least about 60 grams per square meter, at least about 70 grams per square meter, or at least about 90 grams per square meter.

[0125] The hollow tubular element of the downstream section may comprise a polymeric material. For example, the hollow tubular element may comprise a polymeric film. The polymeric film may comprise a cellulose film. The hollow tubular element may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may comprise cellulose acetate tow.

[0126] When the hollow tubular element comprises cellulose acetate tow, the cellulose acetate tow can have a denier per filament of from about 2 to about 4, and a total denier per filament of from about 25 to about 40.

[0127] In some embodiments, aerosol-generating articles according to the invention may include a ventilation zone at a location along the downstream section. More particularly, in those embodiments in which the downstream section comprises a hollow tubular element, a ventilation zone may be provided at a location along the hollow tubular element.

[0128] The ventilated cavity is therefore located downstream of the rod of the aerosol-generating substrate, which provides a particularly efficient cooling of the aerosol and promotes improved nucleation of the aerosol particles.

[0129] The ventilation zone may typically include a plurality of perforations through the circumferential wall of the hollow tubular element. Preferably, the ventilation zone includes at least one circumferential row of perforations. In some embodiments, the ventilation zone may include two circumferential rows of perforations. For example, the perforations may be formed on-line during manufacture of the aerosol-generating article. Preferably, each circumferential row of perforations includes between 8 and 30 perforations.

[0130] The downstream section may further comprise a mouthpiece element. The mouthpiece element may be located at the downstream end of the aerosol-generating article. The mouthpiece element is preferably located downstream of the hollow tubular element of the downstream section, as described above. The mouthpiece element may extend between the hollow tubular element of the downstream section and the downstream end of the aerosol-generating article.

[0131] The provision of a mouthpiece element at the downstream end of an aerosol-generating article according to the present invention provides an appealing appearance and mouth feel to the consumer.

[0132] The mouthpiece element may comprise at least one mouthpiece filter segment formed of a fibrous filtration material. Parameters or characteristics described with respect to the mouthpiece element as a whole may be equally applicable to the mouthpiece filter segment of the mouthpiece element.

[0133] The fibrous filter material may be for filtering the aerosol generated from the aerosol-generating substrate. Suitable fibrous filter materials will be known to those skilled in the art. Particularly preferably, at least one of the mouthpiece filter segments comprises a cellulose acetate filter segment formed from cellulose acetate tow.

[0134] The mouthpiece element may be comprised of a single mouthpiece filter segment. The mouthpiece element may include two or more mouthpiece filter segments axially aligned in abutting end-to-end relationship with one another.

[0135] The downstream section may comprise a mouth-end cavity at a downstream end downstream of the mouthpiece element as described above. The mouth-end cavity may be defined by a further hollow tubular element provided at the downstream end of the mouthpiece element. The mouth-end cavity may be defined by an outer wrapper of the aerosol-generating article, the outer wrapper extending in a downstream direction from (or past) the mouthpiece element.

[0136] The mouthpiece element may optionally include a flavorant, which may be provided in any suitable form, for example, the mouthpiece element may comprise one or more capsules, beads, or granules of flavorant, or one or more threads or filaments loaded with flavor.

[0137] Preferably, the mouthpiece element, or the mouthpiece filter segment thereof, has a low particle filtration efficiency.

[0138] Preferably the mouthpiece element is surrounded by a plug wrap. Preferably the mouthpiece element is non-ventilated so that air does not enter the aerosol-generating article along the mouthpiece element.

[0139] The mouthpiece element preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The diameter of the mouthpiece element (or mouthpiece filter segment) may be substantially the same as the outer diameter of the hollow tubular element. As discussed in this disclosure, the outer diameter of the hollow tubular element may be approximately 7.2 mm plus or minus 10 percent.

[0140] The diameter of the mouthpiece element may be about 5 mm to about 10 mm. The diameter of the mouthpiece element may be about 6 mm to about 8 mm. The diameter of the mouthpiece element may be about 7 mm to about 8 mm. The diameter of the mouthpiece element may be about 7.2 mm ± 10 percent. The diameter of the mouthpiece element may be about 7.25 mm ± 10 percent.

[0141] Unless otherwise specified, the resistance to draw (RTD) of a component or aerosol-generating article is measured in accordance with ISO 6565-2015. RTD refers to the pressure required to force air through the entire length of the component. The terms "pressure drop" or "draw resistance" of a component or article may also refer to "resistance to draw." These terms generally refer to measurements in accordance with ISO 6565-2015 being performed normally under test at a temperature of about 22 degrees Celsius, a pressure of about 101 kPa (about 760 Torr), and a relative humidity of about 60%, with a volumetric flow rate of about 17.5 milliliters per second at the output or downstream end of the component being measured.

[0142] The resistance to withdrawal (RTD) of the downstream section can be at least about 0 mmH2O. The RTD of the downstream section can be at least about 3 mmH2O. The RTD of the downstream section can be at least about 6 mmH2O.

[0143] The RTD of the downstream section can be about 12 mmH2O or less. The RTD of the downstream section can be about 11 mmH2O or less. The RTD of the downstream section can be about 10 mmH2O or less.

[0144] The resistance to withdrawal in the downstream section may be about 0 mmH2O or more and less than about 12 mmH2O. Preferably, the resistance to withdrawal in the downstream section may be about 3 mmH2O or more and less than about 12 mmH2O. The resistance to withdrawal in the downstream section may be about 0 mmH2O or more and less than about 11 mmH2O. Even more preferably, the resistance to withdrawal in the downstream section may be about 3 mmH2O or more and less than about 11 mmH2O. Even more preferably, the resistance to withdrawal in the downstream section may be about 6 mmH2O or more and less than about 10 mmH2O. Preferably, the resistance to withdrawal in the downstream section may be about 8 mmH2O.

[0145] The resistance to withdrawal (RTD) characteristics of the downstream section may be entirely or predominantly due to the RTD characteristics of the mouthpiece elements of the downstream section, in other words, the RTD of the mouthpiece elements of the downstream section may completely dictate the RTD of the downstream section.

[0146] The resistance to draw (RTD) of the mouthpiece element may be at least about 0 mmH2O. The RTD of the mouthpiece element may be at least about 3 mmH2O. The RTD of the mouthpiece element may be at least about 6 mmH2O.

[0147] The RTD of the mouthpiece element may be about 12 mmH2O or less. The RTD of the mouthpiece element may be about 11 mmH2O or less. The RTD of the mouthpiece element may be about 10 mmH2O or less.

[0148] The resistance to withdrawal of the mouthpiece element may be about 0 mmH2O or more and less than about 12 mmH2O. Preferably, the resistance to withdrawal of the mouthpiece element may be about 3 mmH2O or more and less than about 12 mmH2O. The resistance to withdrawal of the mouthpiece element may be about 0 mmH2O or more and less than about 11 mmH2O. Even more preferably, the resistance to withdrawal of the mouthpiece element may be about 3 mmH2O or more and less than about 11 mmH2O. Even more preferably, the resistance to withdrawal of the mouthpiece element may be about 6 mmH2O or more and less than about 10 mmH2O. Preferably, the resistance to withdrawal of the mouthpiece element may be about 8 mmH2O.

[0149] As described above, the mouthpiece element or mouthpiece filter segment may be formed of a fibrous material. The mouthpiece element may be formed of a porous material. The mouthpiece element may be formed of a biodegradable material. The mouthpiece element may be formed of a cellulosic material, such as cellulose acetate. For example, the mouthpiece element may be formed of a bundle of cellulose acetate fibers having about 10 to about 15 denier per filament. For example, the mouthpiece element may be formed of a relatively low density cellulose acetate tow, such as a cellulose acetate tow containing about 12 denier fibers per filament.

[0150] The mouthpiece element may be formed of a polylactic acid-based material. The mouthpiece element may be formed of a bioplastic material, preferably a starch-based bioplastic material. The mouthpiece element may be made by injection molding or extrusion. Bioplastic-based materials are advantageous because they can provide a simple and inexpensive mouthpiece element structure to manufacture with specific and complex cross-sectional profiles that may include multiple relatively large airflow channels extending through the material of the mouthpiece element that provide suitable RTD characteristics.

[0151] The mouthpiece elements may be formed from sheets of suitable material that are crimped, pleated, assembled, woven, or folded into elements that define a plurality of longitudinally extending channels. Such sheets of suitable material may be formed of paper, cardboard, polymers such as polylactic acid, or any other cellulosic, paper, or bioplastic-based material. The cross-sectional profile of such mouthpiece elements may exhibit randomly oriented channels.

[0152] The mouthpiece element may be formed in any other suitable manner. For example, the mouthpiece element may be formed from a bundle of longitudinally extending tubes. The longitudinally extending tubes may be formed from polylactic acid. The mouthpiece element may be formed by extrusion, molding, lamination, injection molding, or shredding of suitable materials. Therefore, it is preferred that there is a low pressure drop (or RTD) from the upstream end of the mouthpiece element to the downstream end of the mouthpiece element.

[0153] The length of the mouthpiece element may be at least about 1.5 mm. The length of the mouthpiece element may be at least about 2 mm. The length of the mouthpiece element may be about 7 mm or less. The length of the mouthpiece element may be about 4 mm or less. For example, the length of the mouthpiece element may be from about 1.5 mm to about 7 mm. The length of the mouthpiece element may be from about 2 mm to about 4 mm.

[0154] The ratio of the length of the mouthpiece element to the length of the downstream section may be about 0.35 or less. Preferably, the ratio of the length of the mouthpiece element to the length of the downstream section may be about 0.30 or less. More preferably, the ratio of the length of the mouthpiece element to the length of the downstream section may be about 0.25 or less.

[0155] The ratio of the length of the mouthpiece element to the length of the downstream section may be at least about 0.03. Preferably, the ratio of the length of the mouthpiece element to the length of the downstream section may be at least about 0.05. More preferably, the ratio of the length of the mouthpiece element to the length of the downstream section may be at least about 0.1.

[0156] For example, the ratio of the length of the mouthpiece element to the length of the downstream section is from about 0.03 to about 0.35, preferably from about 0.05 to about 0.30, and more preferably from about 0.1 to about 0.25.

[0157] The ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article may be about 0.20 or less. Preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article may be about 0.15 or less. More preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article may be about 0.1 or less.

[0158] The ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article may be at least about 0.01. Preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article may be at least about 0.02. More preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article may be at least about 0.05.

[0159] For example, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article is from about 0.01 to about 0.2, preferably from about 0.02 to about 0.15, and more preferably from about 0.05 to about 0.1.

[0160] In embodiments where the downstream section comprises a hollow tubular element and a mouthpiece element, the ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 1.5. In other words, the length of the hollow tubular element may be at least about 150% of the length of the mouthpiece. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 5. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 7.5.

[0161] The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be less than or equal to about 20. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be less than or equal to about 15. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be less than or equal to about 12.5.

[0162] For example, the ratio of the length of the hollow tubular element to the length of the mouthpiece element can be from about 1.5 to about 20, or from about 5 to about 15, or from about 7.5 to about 10.

[0163] The overall length of the downstream section is preferably at least about 15 millimeters, more preferably at least about 20 millimeters, and more preferably at least about 25 millimeters.

[0164] The overall length of the downstream section is preferably less than about 50 millimeters, more preferably less than about 45 millimeters, and more preferably less than about 40 millimeters.

[0165] For example, the downstream section can have an overall length of about 20 millimeters to about 50 millimeters, more preferably about 25 millimeters to about 45 millimeters, and more preferably about 30 millimeters to about 40 millimeters.

[0166] The ratio of the length of the downstream section to the overall length of the aerosol-generating article may be about 0.80 or less. Preferably, the ratio of the length of the downstream section to the overall length of the aerosol-generating article may be about 0.75 or less. More preferably, the ratio of the length of the downstream section to the overall length of the aerosol-generating article may be about 0.70 or less. Even more preferably, the ratio of the length of the downstream section to the overall length of the aerosol-generating article may be about 0.65 or less.

[0167] The ratio of the length of the downstream section to the overall length of the aerosol-generating article may be at least about 0.30. Preferably, the ratio of the length of the downstream section to the overall length of the aerosol-generating article may be at least about 0.40. More preferably, the ratio of the length of the downstream section to the overall length of the aerosol-generating article may be at least about 0.50. Even more preferably, the ratio of the length of the downstream section to the overall length of the aerosol-generating article may be at least about 0.60.

[0168] Preferably, the overall length of an aerosol-generating article according to the invention is at least about 35 millimeters. More preferably, the overall length of an aerosol-generating article according to the invention is at least about 40 millimeters. Even more preferably, the overall length of an aerosol-generating article according to the invention is at least about 45 millimeters. Even more preferably, the overall length of an aerosol-generating article according to the invention is at least about 50 millimeters.

[0169] Preferably, the overall length of the aerosol-generating article according to the invention is 110 mm or less. More preferably, the overall length of the aerosol-generating article according to the invention is 100 mm or less. Even more preferably, the overall length of the aerosol-generating article according to the invention is 75 mm or less. Even more preferably, the overall length of the aerosol-generating article according to the invention is 70 mm or less.

[0170] For example, the overall length of the aerosol-generating article may be from about 35 millimeters to about 110 millimeters, or from about 40 millimeters to about 100 millimeters, or from about 45 millimeters to about 75 millimeters, or from about 50 millimeters to about 70 millimeters.

[0171] Preferably, the aerosol-generating article has an outer diameter of at least 4 millimeters. Preferably, the aerosol-generating article has an outer diameter of at least 4.5 millimeters. More preferably, the aerosol-generating article has an outer diameter of at least 5 millimeters.

[0172] Preferably, the aerosol-generating article has an outer diameter of about 9 millimeters or less. More preferably, the aerosol-generating article has an outer diameter of about 8 millimeters or less. Even more preferably, the aerosol-generating article has an outer diameter of about 7 millimeters or less.

[0173] For example, the aerosol-generating article may have an outer diameter of from about 4 millimeters to about 9 millimeters, or from about 4.5 millimeters to about 8 millimeters, or from about 5 millimeters to about 7 millimeters.

[0174] The outer diameter of the aerosol-generating article may be substantially constant over the entire length of the article, or alternatively, different portions of the aerosol-generating article may have different outer diameters.

[0175] In certain embodiments of the invention, one or more of the components of the aerosol-generating article are individually surrounded by their own wrapper.

[0176] The aerosol-generating substrate and downstream section are preferably combined together with an outer wrapper, such as a tipping wrapper.

[0177] The components of the aerosol-generating article according to the present invention are preferably made from biodegradable materials.

[0178] Preferably, the aerosol-generating articles according to the invention described herein are adapted for use in electrically operated aerosol generating systems in which the aerosol-generating substrate of the heated aerosol-generating article is heated by an electrical heat source.

[0179] The heating element of such an aerosol-generating device may be of any suitable form for conducting heat. Heating of the aerosol-generating substrate may be accomplished internally, externally, or both. The heating element may preferably be a heater blade or pin adapted to be inserted into the substrate such that the substrate is heated from the inside. The heating element may partially or completely surround the substrate and heat the substrate circumferentially from the outside.

[0180] The aerosol-generating system may be an electrically operated aerosol-generating system equipped with an induction heating device. The induction heating device typically includes an induction source configured to be coupled to the susceptor, which may be provided external to the aerosol-generating substrate or internal to the aerosol-generating substrate as described in certain embodiments of the invention described herein. The induction source generates an alternating electromagnetic field, which induces magnetization or eddy currents in the susceptor. The susceptor may be heated as a result of hysteresis losses or induced eddy currents, which heat the susceptor by ohmic or resistive heating.

[0181] An electrically powered aerosol generating system comprising an inductive heating device may also comprise an aerosol-generating article having an aerosol-generating substrate and a susceptor in thermal proximity to the aerosol-generating substrate. Typically, the susceptor is in direct contact with the aerosol-generating substrate and heat is transferred from the susceptor to the aerosol-generating substrate primarily by conduction. Examples of electrically powered aerosol generating systems comprising an inductive heating device and an aerosol-generating article having a susceptor are described in International Application No. WO-A1-95 / 27411 and International Application No. WO-A1-2015 / 177255.

[0182] An electrically operated aerosol generating system may in some cases comprise an aerosol generating article as defined above, a source of aerosol former, a means for vaporizing the aerosol former, and preferably a heating element. The source of aerosol former may be a reservoir present on the aerosol generating device, which may be refillable or replaceable. The reservoir is physically separate from the aerosol generating article, while the generated vapor is directed through the aerosol generating article. The vapor contacts the aerosol generating substrate, releasing volatile compounds, such as nicotine and flavorants in the particulate plant material, to form an aerosol. Optionally, to assist in the vaporization of compounds within the aerosol generating substrate, the aerosol generating system may further comprise a heating element, preferably in a manner coordinated with the aerosol former, to heat the aerosol generating substrate. However, in certain embodiments, the heating element used to heat the aerosol generating article is separate from the heater that heats the aerosol former.

[0183] As mentioned above, the hollow tubular substrate element of the aerosol-generating article according to the invention may advantageously be adapted such that its length substantially matches the longitudinal dimension of the heating element of the aerosol-generating system which is intended to be used to heat the aerosol-generating article, thereby ensuring that the hollow tubular substrate element is heated substantially along its entire length, so that aerosol generation from the aerosol-generating substrate may be maximised. [Brief description of the drawings]

[0184] [Figure 1] FIG. 1 shows a schematic cross-sectional side view of an aerosol-generating article according to a first embodiment of the present invention. [Diagram 2] FIG. 2 shows a schematic cross-sectional side view of an aerosol generating system comprising an aerosol generating article according to a second embodiment of the invention and an aerosol generating device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0185] Specific embodiments will now be further described, by way of example only, with reference to the accompanying drawings in which:

[0186] 1 comprises an aerosol-generating substrate 12 and a downstream section 14 located downstream of the aerosol-generating substrate 12. The aerosol-generating article 10 thus extends from an upstream or distal end 16, which is substantially coincident with the upstream end of the aerosol-generating substrate 12, to a downstream or oral end 18, which is coincident with the downstream end of the downstream section 14. The downstream section 14 comprises a hollow tubular element 20 and a mouthpiece element 50.

[0187] The aerosol-generating article 10 has an overall length of about 45 millimeters and an outer diameter of about 7.2 mm.

[0188] The aerosol-generating substrate 12 comprises a hollow tubular substrate element 40 formed from multiple layers of homogenized tobacco material helically wound around the longitudinal axis of the hollow tubular substrate element. The layers of homogenized tobacco material include multiple layers of cast leaf alternating with layers of cigarillo paper. The hollow tubular substrate element 40 has a peripheral wall 42 formed from overlapping layers of homogenized tobacco material. The peripheral wall 42 defines a central longitudinal airflow channel 44 extending through the hollow tubular substrate element 40. The upstream end of the airflow channel 44 provides an air inlet through which air may be drawn into the aerosol-generating article during use. The hollow tubular substrate element 40 is unwrapped such that the layers of homogenized tobacco material are visible on the exterior surface of the aerosol-generating article.

[0189] The hollow tubular substrate element 40 does not contribute substantially to the overall RTD of the aerosol-generating article. Thus, the RTD of the hollow tubular substrate element 40 is about 0 mmH2O.

[0190] The hollow tubular element 20 of the downstream section 14 is located immediately downstream of the hollow tubular substrate element 40, such that the hollow tubular element 20 is in longitudinal alignment with the aerosol-generation substrate 12. The upstream end of the hollow tubular element 20 abuts the downstream end of the hollow tubular substrate element 40.

[0191] The hollow tubular element 20 is provided in the form of a hollow cylindrical tube made of cellulose acetate tow. The hollow tubular element 20 defines an interior cavity 22 that extends from the upstream end of the hollow tubular element 20 all the way to the downstream end of the hollow tubular element 20. The interior cavity 22 is substantially empty, such that substantially unrestricted airflow is possible therealong. The hollow tubular element 20 does not substantially contribute to the overall RTD of the aerosol-generating article 10. Thus, the RTD of the hollow tubular element 20 is about 0 mmH2O.

[0192] As shown in FIG. 1, the inner diameter of the hollow tubular element 20 in the downstream section 14 is substantially the same as the inner diameter of the hollow tubular substrate element 40 .

[0193] The mouthpiece element 50 extends from the downstream end of the hollow tubular element 20 to the downstream or mouth end 18 of the aerosol-generating article 10. The mouthpiece element 50 comprises a low density cellulose acetate filter segment. The mouthpiece element 50 may be individually wrapped by a plug wrap (not shown).

[0194] The article 10 includes a tipping wrapper 52 surrounding the hollow tubular element 20 and the mouthpiece element 50. The tipping wrapper 52 further overlies an upstream portion of the hollow tubular substrate element 40 to join the hollow tubular substrate element 40 and the downstream section 14.

[0195] The aerosol-generating article 10 is particularly suitable for use in an aerosol-generating device that includes an external heating means for externally heating the aerosol-generating substrate 12. Thus, during use, the aerosol-generating article 10 is preferably inserted into a heating cavity of the aerosol-generating device with the outer surface of the hollow tubular substrate element 40 adjacent a heating element within the cavity. Upon heating the hollow tubular substrate element 40, an aerosol is generated from the layered homogenized tobacco, which is drawn through the peripheral wall 42 into the longitudinal airflow channel 44 of the hollow tubular substrate element 40, together with air that enters the longitudinal airflow channel 44 at the upstream end, when the consumer draws on the article. The combined air and aerosol are drawn through the aerosol-generating article 10 and delivered to the consumer from the downstream end of the aerosol-generating article 10.

[0196] Figure 2 shows an aerosol-generating system 100 comprising an aerosol-generating device 102 and an aerosol-generating article 110 according to a second embodiment of the invention. The aerosol-generating article 110 is similar to that shown in Figure 1 and described above, and has a similar arrangement of components. However, the aerosol-generating article 110 further comprises a tubular susceptor element 160 within the longitudinal airflow channel 144 of the hollow tubular substrate element 140. The tubular susceptor element 160 is disposed on the inner surface of the longitudinal airflow channel 144.

[0197] As shown in Figure 2, the aerosol generating device 102 comprises a longitudinal heating cavity 104 for receiving an aerosol-generating article 110. The heating cavity 104 has a closed distal end and an open mouth end. An airflow inlet 106 is located at the distal end of the cavity such that air may be drawn through the aerosol-generating article 110 during use. The heating cavity 104 comprises an arrangement of an inductor coil 108 for inductively heating a tubular susceptor element 160 during use.

[0198] The aerosol generating device 102 further comprises a power supply (not shown) for supplying power to the inductor coil 108, and a control device (not shown) for controllably heating the aerosol generating article 110 during use when the aerosol generating article 110 is received within the device 102. EXAMPLES

[0199] Below is provided a non-exhaustive list of non-limiting examples, any one or more of the features of which may be combined with any one or more features of the other examples, embodiments, or aspects described herein.

[0200] Example 1. An aerosol-generating article comprising: an aerosol-generating substrate comprising a hollow tubular substrate element having a multi-layered peripheral wall defining a longitudinal airflow channel, the peripheral wall being formed from a plurality of overlapping layers of homogenized tobacco material; and a downstream section provided downstream of the aerosol-generating substrate. Example 2. 2. The aerosol-generating article of example 1, wherein the longitudinal airflow channel has a diameter of at least 3 millimeters. Example 3. 3. The aerosol-generating article of any one of claims 1 to 2, wherein the hollow tubular substrate element comprises at least two overlapping layers of homogenized tobacco material. Example 4. An aerosol-generating article as described in any of Examples 1-3, wherein the hollow tubular substrate element comprises up to 10 overlapping layers of homogenized tobacco material. Example 5. An aerosol-generating article according to any one of Examples 1 to 4, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least about 0.3. Example 6. An aerosol-generating article according to any one of Examples 1 to 5, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least about 0.7. Example 7. An aerosol-generating article as described in any one of Examples 1 to 6, wherein the peripheral wall of the hollow tubular substrate element has a density of at least 200 milligrams per cubic centimeter. Example 8. An aerosol-generating article according to any one of Examples 1 to 7, wherein the peripheral wall of the hollow tubular substrate element has a density of less than 1 gram per cubic centimeter. Example 9. An aerosol-generating article as described in any of Examples 1-8, wherein the peripheral wall of the hollow tubular substrate element provides at least 150 milligrams of homogenized tobacco material per centimeter of hollow tubular substrate length. Example 10. 10. An aerosol-generating article as claimed in any one of Examples 1 to 9, wherein the hollow tubular substrate element has a longitudinal tensile strength of from 11 kNewtons / meter to 14 kNewtons / meter. Example 11. An aerosol-generating article as claimed in any one of Examples 1 to 10, wherein the hollow tubular base element has an axial compressive strength of 7 MPa to 9 MPa. Example 12. An aerosol-generating article as claimed in any one of Examples 1 to 11, wherein the hollow tubular substrate element has a radial compressive strength of between 7 MPa and 9 MPa. Example 13. An aerosol-generating article according to any one of Examples 1 to 12, wherein the hollow tubular substrate element has a length of up to 40 millimeters. Example 14. An aerosol-generating article according to any one of Examples 1 to 13, wherein the hollow tubular substrate element has a length of at least 10 millimeters. Example 15. An aerosol-generating article according to any one of Examples 1 to 14, wherein the ratio between the length of the hollow tubular substrate element and the overall length of the aerosol-generating article is at least 0.15. Example 16. An aerosol-generating article according to any one of Examples 1 to 15, wherein the ratio between the length of the hollow tubular substrate element and the overall length of the aerosol-generating article is at most 0.6. Example 17. An aerosol-generating article according to any one of Examples 1 to 16, wherein the hollow tubular substrate element has an outer diameter of at least 4 millimeters. Example 18. An aerosol-generating article according to any one of Examples 1 to 17, wherein the hollow tubular substrate element has an outer diameter of up to 9 millimeters. Example 19. An aerosol-generating article as described in any of Examples 1-18, wherein the hollow tubular substrate element provides an unrestricted flow channel. Example 20. An aerosol-generating article as described in any one of Examples 1-19, wherein the longitudinal airflow channel of the hollow tubular substrate element has a diameter of up to 7 millimeters. Example 21. 21. An aerosol-generating article according to any one of Examples 1 to 20, wherein the ratio of the inner diameter to the outer diameter of the hollow tubular substrate element is at least 0.4. Example 22. An aerosol-generating article according to any one of Examples 1 to 21, wherein the peripheral wall has a thickness of at least 1 millimeter. Example 23. An aerosol-generating article as described in any one of Examples 1 to 22, wherein the peripheral wall has a wall thickness of up to 2.25 millimeters. Example 24. An aerosol-generating article as described in any of Examples 1-23, wherein multiple layers of homogenized tobacco material are helically wound around the longitudinal axis of the hollow tubular substrate element. Example 25. An aerosol-generating article as described in any of Examples 1-24, wherein the hollow tubular substrate element further comprises an adhesive for sealing adjacent layers to one another. Example 26. An aerosol-generating article according to any one of Examples 1 to 25, wherein the aerosol-generating substrate further comprises a sealing element at the upstream end of the hollow tubular substrate element, covering the upstream end of the hollow tubular substrate element. Example 27. An aerosol-generating article as described in any of Examples 1-26, wherein the homogenized plant material has a tobacco content of at least 40 percent by weight on a dry weight basis. Example 28. An aerosol-generating article according to any one of Examples 1 to 27, wherein the homogenized tobacco material further comprises one or more aerosol formers. Example 29. 29. The aerosol-generating article of Example 28, wherein the homogenized tobacco material has an aerosol former content of between 5 weight percent and 30 weight percent on a dry weight basis. Example 30. An aerosol-generating article as described in any of Examples 1 to 29, wherein the peripheral wall comprises one or more layers of a first homogenized tobacco material and one or more layers of one or more second homogenized tobacco materials different from the first homogenized tobacco material. Example 31. An aerosol-generating article as described in Example 30, wherein the first and second homogenized tobacco materials have different tobacco contents from each other. Example 32. 32. The aerosol-generating article of Example 30 or 31, wherein the first and second homogenized tobacco materials have different aerosol former contents. Example 33. 33. An aerosol-generating article as described in any one of Examples 1-32, wherein the multiple layers of homogenized tobacco material comprise one or more sheets of cast leaf. Example 34. 34. The aerosol-generating article of example 33, wherein the cast leaves have a porosity of between 20 percent and 60 percent. Example 35. An aerosol-generating article as described in any of Examples 1-34, wherein the multiple layers of homogenized tobacco material include one or more layers of cigarillo paper. Example 36. 36. The aerosol-generating article of example 35, wherein the cigarillo paper has a porosity of 30 percent to 80 percent. Example 37. 37. The aerosol-generating article of any one of Examples 1 to 36, wherein the hollow tubular substrate element comprises one or more susceptor elements positioned in contact with the peripheral wall. Example 38. 38. The aerosol-generating article of Example 37, wherein the hollow tubular substrate element comprises one or more susceptor elements on a surface of the peripheral wall. Example 39. 39. The aerosol-generating article of Example 38, wherein the hollow tubular substrate element comprises a tubular susceptor element disposed on at least one surface of a peripheral wall thereof. Example 40. An aerosol-generating article as described in any one of Examples 1-39, wherein the downstream section comprises a hollow tubular element. Example 41. An aerosol-generating article as described in Example 40, wherein the length of the hollow tubular element in the downstream section is between 12 mm and 50 mm. Example 42. 42. The aerosol-generating article of embodiment 40 or 41, wherein the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section is at least 0.25. Example 43. 43. An aerosol-generating article according to any one of Examples 40 to 42, wherein the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section is 1.25 or less. Example 44. An aerosol-generating article as described in any of Examples 40 to 43, wherein the ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section is at least 0.35. Example 45. 45. An aerosol-generating article according to any one of Examples 40 to 44, wherein the ratio of the length of the hollow tubular element in the downstream section to the total length of the downstream section is 1 or less. Example 46. An aerosol-generating article described in any of Examples 40 to 45, wherein the ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article is at least 0.25. Example 47. An aerosol-generating article as described in any of Examples 40 to 46, wherein the ratio of the length of the hollow tubular element in the downstream section to the overall length of the aerosol-generating article is 0.8 or less. Example 48. An aerosol-generating article as described in any of Examples 40 to 47, wherein the wall thickness of the hollow tubular element in the downstream section is at least 100 micrometers. Example 49. An aerosol-generating article described in any of Examples 40 to 48, wherein the wall thickness of the hollow tubular element in the downstream section is 2 millimeters or less. Example 50. An aerosol-generating article described in any of Examples 40 to 49, wherein the hollow tubular element of the downstream section has an inner diameter of 2 millimeters to 10 millimeters. Example 51. 51. An aerosol-generating article according to any one of Examples 40 to 50, wherein the ratio of the inner diameter of the hollow tubular base element to the inner diameter of the hollow tubular element in the downstream section is 0.8 to 1.2. Example 52. An aerosol-generating article described in any one of Examples 1 to 51, wherein the downstream section further comprises a mouthpiece element. Example 53. An aerosol-generating article as described in Example 52, wherein the mouthpiece element comprises at least one segment of fibrous filtration material. Example 54. 54. An aerosol-generating article as described in Example 52 or 53, wherein the downstream section comprises an oral end cavity at a downstream end downstream of the mouthpiece element. Example 55. The aerosol-generating article according to any one of Examples 52 to 54, wherein the length of the mouthpiece element is 1.5 mm to 7 mm. Example 56. An aerosol-generating article described in any of Examples 52 to 55, wherein the ratio of the length of the mouthpiece element to the length of the downstream section is 0.35 or less. Example 57. 57. An aerosol-generating article according to any one of Examples 52 to 56, wherein the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article is 0.20 or less. Example 58. An aerosol-generating article as described in any one of Examples 1 to 57, wherein the RTD of the downstream section is 12 millimeters H2O or less. Example 59. An aerosol-generating article as described in any one of Examples 1 to 58, wherein the length of the downstream section is between 20 millimeters and 50 millimeters. Example 60. An aerosol-generating article as described in any one of Examples 1 to 59, wherein the ratio of the total length of the downstream section to the total length of the aerosol-generating article is 0.80 or less. Example 61. An aerosol-generating article according to any one of Examples 1 to 60, wherein a component of the aerosol-generating article is made from a biodegradable material.

Claims

1. An aerosol-generating article comprising: an aerosol-generating substrate comprising a hollow tubular substrate element having a multi-layered peripheral wall defining a longitudinal airflow channel, the peripheral wall being formed from a plurality of overlapping layers of homogenized tobacco material, the peripheral wall having a density of at least 200 milligrams per cubic centimeter, and the longitudinal airflow channel having a diameter of at least 3 millimeters; a downstream section provided downstream of the aerosol-generating substrate.

2. 2. The aerosol-generating article of claim 1, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least 0.

3.

3. 2. The aerosol-generating article of claim 1, wherein the peripheral wall comprises one or more layers of a first homogenized tobacco material and one or more layers of a second homogenized tobacco material having a different composition than the first homogenized tobacco material.

4. 4. The aerosol-generating article of claim 3, wherein the first homogenized tobacco material and the second homogenized tobacco material have different porosities.

5. 10. The aerosol-generating article of claim 1, wherein the plurality of layers of homogenized tobacco material are helically wound around the longitudinal axis of the hollow tubular substrate element.

6. 10. The aerosol-generating article of claim 1, wherein the peripheral wall of the hollow tubular substrate element provides at least 150 milligrams of homogenized tobacco material per centimeter of the hollow tubular substrate element.

7. The aerosol-generating article of claim 1 , further comprising a susceptor element.

8. 8. The aerosol-generating article of claim 7, further comprising a tubular susceptor element on at least one surface of the hollow tubular substrate element.

9. 2. The aerosol-generating article of claim 1, wherein the outer surface of the hollow tubular substrate element is at least partially exposed on the outer surface of the aerosol-generating article.

10. 10. The aerosol-generating article of claim 1, wherein the hollow tubular substrate element has a length of at least 15 millimeters.

11. 2. The aerosol-generating article of claim 1, wherein the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least 0.

15.

12. The aerosol-generating article of claim 1 , wherein the downstream section comprises at least one hollow tubular element.

13. 13. The aerosol-generating article of claim 12, wherein the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element in the downstream section is between 0.25 and 1.

25.

14. 13. The aerosol-generating article of claim 12, wherein the downstream section further comprises a mouthpiece element at the downstream end of the aerosol-generating article.

Images