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

Abstract

The aerosol-generating article (10)(110) comprises an aerosol-generating substrate (12) comprising a hollow tubular substrate element (40) having a peripheral wall (42) defining a longitudinal airflow channel (44) extending between upstream and downstream ends of the hollow tubular substrate element (40), the peripheral wall (42) being formed from one or more layers of homogenized plant material; a sealing element (24) at the upstream end of the hollow tubular substrate element (40), the sealing element (24) being arranged to provide a substantially airtight seal at the upstream end of the longitudinal airflow channel (44); and a downstream section (14) located 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 the 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 and 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, electrically heated aerosol generating devices have been proposed, which include an internal heater blade adapted to be inserted into the aerosol-generating substrate. The use of aerosol-generating articles in combination with external heating systems is also known. For example, WO 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 WO 2015 / 176898, which includes an aerosol-generating substrate and a susceptor disposed within the aerosol-generating substrate. Summary of the Invention [Problem to be solved by the invention]

[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] Aerosol-generating articles are designed to provide a specific airflow pattern during use, which determines where air is drawn into the aerosol-generating article during use, how the air flows through the aerosol-generating article, and how the air mixes with the aerosol generated from the aerosol-generating substrate. Many existing aerosol-generating articles are designed to provide a longitudinal airflow, meaning that air is drawn longitudinally through the article from the upstream end to the downstream end. Aerosol-generating articles that provide a transverse airflow, in which air is drawn transversely or circumferentially through the aerosol-generating substrate from the outside to the inside of the article, are also known. In such articles, a transverse airflow is provided instead of a longitudinal airflow.

[0006] It has proven technically challenging to provide an aerosol-generating article that can utilize both longitudinal and transverse airflow during use, while retaining other desirable characteristics, such as an acceptable level of resistance to draw (RTD) and the required level of ventilation.

[0007] It would therefore be desirable to provide an aerosol-generating article that is adapted to provide greater flexibility in the airflow that can be provided. In particular, it would be desirable to be able to utilize both longitudinal and transverse airflows on the same article while maintaining the desired properties of the article. It would particularly be desirable to provide such an article with a relatively simple design so that it can be manufactured in a cost-effective manner and incorporated into existing product designs. It would therefore be further desirable to provide an aerosol-generating article having an aerosol-generating substrate that is adapted to provide more efficient aerosolization of the aerosol-generating substrate and reduces waste of substrate material, such as tobacco. It would further be desirable to provide such an article that can be easily adapted so that it can be heated with various types of heating devices, including induction heating devices and resistance heating devices. [Brief description of the drawings]

[0008] [Figure 1] 1 shows a schematic cross-sectional side view of an aerosol-generating article according to a first embodiment of the present invention. [Diagram 2] 2 shows a schematic cross-sectional side view of an aerosol-generating article according to a second embodiment of the present invention. [Diagram 3] FIG. 1 shows a schematic cross-sectional side view of an aerosol generating system comprising an aerosol generating article and an aerosol generating device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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 peripheral wall defining a longitudinal airflow channel extending between an upstream end and a downstream end of the hollow tubular substrate element. The peripheral wall may be formed of one or more layers of homogenized plant material. The aerosol-generating article may further comprise a sealing element at the upstream end of the hollow tubular substrate element. The sealing element may be arranged to provide a substantially airtight seal at the upstream end of the hollow tubular substrate element. The aerosol-generating article may further comprise a downstream section located downstream of the aerosol-generating substrate.

[0010] 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 peripheral wall defining a longitudinal airflow channel extending between upstream and downstream ends of the hollow tubular substrate element, the peripheral wall being formed from one or more layers of homogenised plant material; a sealing element at the upstream end of the hollow tubular substrate element, the sealing element being arranged to provide a substantially airtight seal at the upstream end of the longitudinal channel; and a downstream section located downstream of the aerosol-generating substrate.

[0011] 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 burned 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 burning 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.

[0012] Also known are aerosol-generating articles adapted for use in aerosol-generating systems that supply aerosol formers to the aerosol-generating article, where the aerosol-generating substrate within 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 formers used to form the aerosol.

[0013] The term "aerosol-generating substrate" as used herein refers to a substrate capable of releasing, upon heating, volatile compounds capable of forming an aerosol. The aerosol generated from the aerosol-generating substrate of the aerosol-generating articles 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 condensed vapor.

[0014] 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 molding, extrusion, papermaking processes, or any other suitable process known in the art.

[0015] As used herein, the term "substantially airtight seal" means that the sealing element provides a seal over the upstream end of the longitudinal channel that substantially prevents air from being drawn into the longitudinal channel at the upstream end of the hollow tubular substrate element during normal use of the aerosol-generating article in an aerosol-generating device. Preferably, the sealing element provides an airtight seal that prevents any air from entering the longitudinal channel through the upstream end.

[0016] Thus, in the aerosol-generating article according to the invention, the upstream end of the longitudinal channel is covered and sealed by a sealing element located at the upstream end of the hollow tubular substrate element. With the sealing element in place and remaining unaffected, air cannot enter the longitudinal airflow channel at the upstream end, thus preventing the longitudinal airflow from passing through the longitudinal airflow channel. Instead, the hollow tubular substrate element is adapted such that air is drawn transversely through the peripheral wall from the outside of the hollow tubular substrate element through the layer of homogenized plant material into the longitudinal airflow channel. The hollow tubular substrate element is preferably porous as a result of the arrangement of overlapping layers of homogenized plant material, as will be explained in more detail below.

[0017] Providing a transverse airflow is particularly advantageous when heating of the hollow tubular substrate element occurs from the outside, so that heat is transferred from the outside to the inside of the hollow tubular substrate element through the peripheral wall. A transverse airflow may work particularly effectively due to the tubular shape of the substrate, which provides a relatively thin wall for air to penetrate.

[0018] Once the sealing element is removed or pierced, an opening is placed at the upstream end of the longitudinal airflow channel, allowing longitudinal airflow between the upstream and downstream ends of the hollow tubular substrate element. A combination of longitudinal and transverse airflow is then possible, with the airflow being partially longitudinal and partially transverse. The addition of longitudinal airflow may advantageously improve the flow of the aerosol through the hollow tubular substrate element.

[0019] The inclusion of a sealing element therefore provides much greater flexibility regarding the possible airflow designs that can be achieved for the aerosol-generating article of the present invention. Also, there is greater control over the airflow provided during use such that the aerosol-generating article of the present invention can be more precisely tailored to provide a desired airflow pattern during use. This advantageously allows the aerosol-generating article to be optimized according to the particular design of the aerosol-generating device in which it is intended to be used.

[0020] Thus, the aerosol-generating article according to the present invention provides novel configurations that are capable of providing both longitudinal and transverse airflow, either separately or possibly in combination, during use, and the defined configurations can be incorporated into the aerosol-generating article whilst still achieving the desired levels of ventilation and RTD.

[0021] The sealing element may advantageously be adapted to be automatically pierced, penetrated, or ruptured when the aerosol-generating article is inserted into the heating cavity of the aerosol-generating device. In some cases, the presence of the sealing element may also facilitate proper insertion of the heating element into the article, for example, when an internal heating element is inserted into a hollow tubular base element.

[0022] Furthermore, the sealing element may advantageously prevent contamination or deterioration of the inside of the hollow tubular substrate element prior to use.

[0023] As defined above, the present invention provides an aerosol-generating article having an aerosol-generating substrate in the form of a hollow tubular substrate element. The hollow tubular substrate element comprises one or more layers of homogenized plant material which form the peripheral wall of the hollow tubular substrate element. The "peripheral" wall of the hollow tubular substrate corresponds to the main wall which defines the tubular structure. Preferably, the hollow tubular substrate element consists only of the peripheral wall. The peripheral wall therefore contains all of the homogenized plant material which generates an aerosol upon heating of the aerosol-generating substrate.

[0024] 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 is preferably empty or 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 plant material, including tobacco material.

[0025] By providing an aerosol-generating substrate in a tubular form, the amount of plant 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 plant material that may not be heated as effectively as the outer portion, especially in an aerosol-generating device equipped with an external heating means. Overall, the amount of plant material can therefore be significantly reduced compared to a conventional solid plug of homogenized plant material, reducing plant waste. For example, when the homogenized plant material includes tobacco particles, 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.

[0026] The amount of plant material provided within the substrate can be easily adapted by controlling the parameters of the hollow tubular substrate element, such as the density and wall thickness of the peripheral wall. 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.

[0027] As mentioned above, the hollow tubular substrate element is formed of one or more layers of homogenized plant material. Preferably, the hollow tubular substrate element is formed by multiple overlapping layers of homogenized plant material. The multiple overlapping layers of homogenized plant material are preferably directly overlaid on each other such that adjacent layers are in direct contact with each other without intermediate layers. The multiple overlapping layers of homogenized plant material may advantageously be arranged to define multiple gaps between adjacent layers. As a result, the peripheral wall typically has a porous structure that allows transverse airflow through the peripheral wall during use, as described above. As will be explained in more detail below, the gaps defined between adjacent layers of homogenized plant 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.

[0028] 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.

[0029] The diameter of the longitudinal airflow channel can be adapted to provide greater control over airflow management through the aerosol-generating article.

[0030] 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.

[0031] 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.

[0032] As mentioned 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 plant material, the layers overlapping each other in the transverse direction to provide a multi-layer structure.

[0033] Preferably, the hollow tubular substrate element comprises at least about two overlapping layers of homogenized plant material, and more preferably, at least about three overlapping layers of homogenized plant material.

[0034] The hollow tubular substrate element preferably contains up to about 10 overlapping layers of homogenized plant material, more preferably up to about 5 overlapping layers of homogenized plant material. For example, the hollow tubular substrate element may contain from about 2 to about 10 overlapping layers of homogenized plant material, or from about 3 to about 5 overlapping layers of homogenized plant material.

[0035] As mentioned above, the peripheral wall of the hollow tubular substrate element preferably has a porous structure as a result of the voids formed between the overlapping layers of homogenized plant material. The peripheral wall is preferably porous both transversely and longitudinally.

[0036] 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.

[0037] 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.

[0038] For example, the cross-sectional porosity of the peripheral wall may 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.

[0039] 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 ​​a peripheral wall of a hollow tubular substrate element. 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.

[0040] Further details regarding the measurement of cross-sectional porosity within a porous or air-permeable body can be found in the publication WO 2016 / 023965 in the name of the applicant.

[0041] The cross-sectional porosity of the peripheral wall allows aerosol to pass transversely through the peripheral wall such that it can be drawn into and through the longitudinal airflow channel.

[0042] 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.

[0043] The peripheral wall of the hollow tubular substrate element preferably has a density of less than about 1 gram per cubic centimeter.

[0044] In the context of the present invention, "density" refers to the bulk density of the peripheral wall including overlapping layers, not the density of the individual layers. A relatively high density of the peripheral wall maximizes the amount of plant 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.

[0045] Preferably, the peripheral wall provides at least about 150 milligrams of homogenized plant material per centimeter of length of the hollow tubular substrate, more preferably at least about 200 milligrams of homogenized plant material per centimeter of length, more preferably at least about 300 milligrams of homogenized plant material per centimeter of length, more preferably at least about 400 milligrams of homogenized plant material per centimeter of length, more preferably at least about 500 milligrams of homogenized plant material per centimeter of length, more preferably at least about 600 milligrams of homogenized plant material per centimeter of length, more preferably at least about 700 milligrams of homogenized plant material per centimeter of length, more preferably at least about 800 milligrams of homogenized plant material per centimeter of length, based on measurements taken at 22.5 degrees Celsius and 60 percent humidity.

[0046] Preferably, the hollow tubular substrate element has a longitudinal tensile strength, measured according to TAPPI test method T494 om-01 2006, of between 11 kNewtons / meter and 14 kNewtons / meter.

[0047] 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).

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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 generated and reduce the amount of waste plant material, such as tobacco waste.

[0053] 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.

[0054] 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.

[0055] 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, and more preferably from about 0.4 to about 0.5.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] Preferably, the outer diameter of the hollow tubular substrate element is substantially the same as the outer diameter of the aerosol-generating article.

[0060] As discussed above, the hollow tubular substrate element provides a longitudinal airflow channel defined by a peripheral wall. The longitudinal airflow channel extends between the upstream and downstream ends of the hollow tubular substrate element and is preferably open at the downstream end. The longitudinal airflow channel provides a primary passageway for the flow of air and aerosols through the article.

[0061] Preferably, the hollow tubular substrate element provides an unrestricted flow channel. This means that the hollow tubular segment provides a negligible level of resistance to withdrawal (RTD). The term "negligible level of RTD" refers to a flow rate of less than 1 mmH per 10 mm of the length of the hollow tubular element. 2 RTD of less than 0.05 mmH2O, preferably 0.4 mmH2O per 10 mm of length of the hollow tubular element 2 10, more preferably less than 0.1 mmH per 10 mm of length of the hollow tubular element. 2 Used to describe RTDs less than 100.

[0062] The longitudinal airflow channels preferably 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.

[0063] 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.

[0064] 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.

[0065] 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 in order to provide a sufficient amount of plant material within the hollow tubular substrate element and such that the hollow tubular substrate element has a sufficiently high rigidity that it can be self-supporting.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] The overlapping layers of homogenized plant material may be arranged in any suitable manner to provide the desired wall thickness and porosity for the peripheral wall. Each layer of homogenized plant material typically extends at least once around the hollow tubular substrate element, and preferably each layer of homogenized plant material extends multiple times around the hollow tubular substrate element to build up the structure of the peripheral wall.

[0073] Preferably, the multiple layers of homogenized plant material are spirally wound around the longitudinal axis of the hollow tubular substrate element, providing a spirally wound structure similar to the layered structure of conventional paper string. Hollow tubular substrate elements incorporating a spiral 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.

[0074] 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 simple longitudinal wrapping. Furthermore, the spirally wound arrangement can provide a more dense homogenized plant material at the peripheral wall. The manufacturing method used to create the spiral arrangement of layers additionally provides greater control over the dimensions of the hollow tubular substrate element, so that the variations in outer and inner diameters are minimized. This provides greater consistency between products.

[0075] 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.

[0076] The peripheral wall of the hollow tubular substrate element formed of one or more layers of homogenized plant material is preferably at least partially exposed on the outer surface of the hollow tubular substrate element. Thus, the hollow tubular substrate element is 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.

[0077] Alternatively, the hollow tubular substrate element may be overwrapped with at least one wrapper. For example, the hollow tubular substrate element may be overwrapped with a conventional paper wrapper. The hollow tubular substrate element may be overwrapped with a tobacco-containing wrapper, such as a tobacco paper wrapper.

[0078] The hollow tubular substrate element is formed of multiple layers of homogenized plant material, which is preferably in sheet form. The term "sheet" as used herein with respect to the present invention refers to a laminar element having a width and length that is significantly greater than its thickness.

[0079] 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.

[0080] Preferably, the homogenized plant material is homogenized tobacco material. 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.

[0081] 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.

[0082] The homogenized plant material preferably includes one or more aerosol formers. Upon volatilization, the aerosol formers can transport 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 well 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).

[0083] The homogenized plant 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 plant material.

[0084] The two or more overlapping layers of homogenized plant material forming the peripheral wall of the hollow tubular substrate element may all be formed of the same homogenized plant material. Alternatively, the peripheral wall includes one or more layers of a first homogenized plant material and one or more layers of a second homogenized plant material different from the first homogenized plant material. Thus, the peripheral wall is formed from a combination of at least two different homogenized plant materials. The first homogenized plant material and the second homogenized plant material may differ from each other in composition. For example, the first and second homogenized plant materials may have different tobacco contents, or different aerosol former contents, or both, from each other. Alternatively, or additionally, the first and second homogenized plant materials may be provided with different levels of flavorants to provide a flavor profile. Alternatively, or additionally, the first homogenized plant material and the second homogenized plant material may differ from each other in one or more physical parameters, including but not limited to density, porosity, or thickness.

[0085] The use of different homogenized plant materials within the hollow tubular substrate element provides greater flexibility for the delivery of aerosols upon heating. For example, the compositions of the first and second homogenized plant materials can be adapted to provide for the delivery of aerosols at different times or rates. The use of different homogenized plant materials can also provide improved stability, for example, by avoiding the combination of potentially incompatible components.

[0086] Preferably, in embodiments in which the aerosol-generating substrate comprises homogenized tobacco material, the multiple layers of homogenized tobacco material comprise one or more sheets of cast leaf.

[0087] 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.

[0088] Alternatively, or in addition to one or more sheets of cast leaf, the multiple layer homogenized tobacco material may include one or more layers of cigarillo paper.

[0089] 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.

[0090] The peripheral wall may be formed of alternating layers of cast leaf and cigarillo paper.

[0091] 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 peripheral wall for inductive heating of the homogenised plant material during use.

[0092] As used herein, the term "susceptor element" refers to an element that includes a material capable of converting electromagnetic energy into heat. When a 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.

[0093] 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.

[0094] 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 the volatile compound from the aerosol-forming 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 include metal or carbon. Advantageously, the susceptor elements may include or consist of ferromagnetic materials, such as, for example, 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 include 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.

[0095] The susceptor element may comprise a non-metallic core having a metal layer disposed thereon. For example, the susceptor element may include a ceramic core or a metal track formed on the outer surface of the substrate.

[0096] The hollow tubular substrate element preferably comprises one or more susceptor elements on a surface of the peripheral wall. The hollow tubular substrate element may comprise one or more susceptor elements on an 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 an outer surface of the peripheral wall.

[0097] 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.

[0098] The use of tubular susceptor elements advantageously optimizes heating of the homogenized plant material within the peripheral wall since the susceptor elements contact a relatively large surface area of ​​the homogenized plant material. Due to the tubular form of the hollow tubular substrate elements, the substrate thickness is relatively small, resulting in efficient heat transfer through the peripheral wall from the side where the tubular susceptor elements are located.

[0099] As defined above, the aerosol-generating article of the present invention further comprises a sealing element located at the upstream end of the hollow tubular substrate element to provide an airtight seal, which prevents air from being drawn into the upstream end of the longitudinal airflow channel during use, thus covering and sealing the opening of the longitudinal airflow channel at the upstream end.

[0100] The sealing element may be formed of any suitable material that can be affixed to the hollow tubular substrate and is substantially impermeable to air such that an airtight seal can be established. The sealing element may be adapted to be removable by the consumer prior to use.

[0101] The sealing element preferably comprises a film layer applied to the peripheral wall at the upstream end of the hollow tubular substrate element. The film layer is preferably penetrable, meaning that it has the ability to be penetrated or punctured by a heating element, susceptor wick, or other penetrating element located in the heating cavity of the aerosol-generating device. This penetration of the film layer preferably occurs when the aerosol-generating article is inserted into the heating cavity prior to use.

[0102] The film layer is preferably formed of a laminate material that includes multiple overlapping layers. The film layer may include one or more polymeric layers. Suitable polymers include, but are not limited to, polyethylene terephthalate (PET), low and high density polyethylene (LDPE and HDPE, respectively), polypropylene (PP), polyvinyl chloride (PVC), polyamides, polyolefins, polystyrene, ethylene vinyl alcohol copolymers, and combinations thereof. Alternatively, or additionally, the film layer may include one or more metal layers, for example, one or more aluminum layers.

[0103] The film layer may be heat welded to the peripheral wall of the hollow tubular substrate element, or alternatively, the film layer may be affixed to the peripheral wall of the hollow tubular substrate element by a suitable adhesive, as described below.

[0104] In an alternative embodiment, the sealing element comprises a paper wrapper. The paper wrapper may be folded over the upstream end of the hollow tubular substrate element. The paper wrapper may be formed of any of the paper materials used to provide plug wraps or tipping wrappers for conventional aerosol-generating articles. To ensure the provision of an airtight seal, the paper wrapper is preferably coated or laminated with an impermeable coating layer, such as a layer of wax. Suitable coating materials will be well known to those skilled in the art.

[0105] The sealing element is preferably affixed to the upstream end of the hollow tubular substrate element by a layer of adhesive, which is preferably provided between the sealing element and the area of ​​the peripheral wall of the hollow tubular substrate element that is covered by the sealing element.

[0106] Suitable adhesives would be well known to those skilled in the art and would include most food grade adhesives, such as polysaccharide adhesives.

[0107] The sealing element may be located only on the upstream surface of the hollow tubular base element. In such an embodiment, the sealing element is affixed to the upstream surface or edge of the peripheral wall. Alternatively, the sealing element may extend from the upstream end along at least some of the outer surface of the peripheral wall of the hollow tubular base element. This may facilitate sealing of the sealing element to the peripheral wall as a result of an increased contact area between the sealing element and the peripheral wall. For example, the sealing element may extend from the upstream end along the outer surface of the peripheral wall at least 1 millimeter, more preferably at least 2 millimeters, more preferably at least 3 millimeters.

[0108] In a particular embodiment, the aerosol-generating article according to the invention further comprises a fastening band extending circumferentially around the hollow tubular substrate element and overlying a portion of the sealing element extending downstream from the upstream end of the hollow tubular substrate element, as described above. The fastening band is preferably affixed to the outer surface of the hollow tubular substrate element. The fastening band is preferably a paper band.

[0109] The provision of a fastening band on the closure element helps to hold the closure element in place on the hollow tubular substrate element. This may also provide the exterior of the hollow tubular substrate element with a more uniform appearance and a more desirable surface texture for consumers. An adhesive is preferably used to attach the fastening band to the exterior surface of the hollow tubular substrate element.

[0110] The fastening band preferably has a length of at least 2 millimeters, more preferably at least 3 millimeters, more preferably at least 4 millimeters.

[0111] 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.

[0112] The downstream section preferably comprises at least one hollow tubular element. The hollow tubular element 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. This arrangement optimizes 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.

[0113] 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.

[0114] 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 is understood that alternative shapes (e.g., alternative cross-sectional shapes) of the tubular segment may be possible. The hollow tubular element may be an individual, separate element of the aerosol-generating article, having a defined length and thickness.

[0115] 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.

[0116] 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 thus acts as an aerosol cooling element.

[0117] The length of the hollow tubular element may be at least about 12 millimeters. The length of the hollow tubular element may be at least about 15 millimeters. The length of the hollow tubular element may be at least about 20 millimeters.

[0118] The length of the hollow tubular element in the downstream section may be about 50 millimeters or less. The length of the hollow tubular element may be about 45 millimeters or less. The length of the hollow tubular element may be about 40 millimeters or less.

[0119] For example, the length of the hollow tubular element in the downstream section may be between about 12 mm and 50 mm. The length of the hollow tubular element may be between about 15 mm and 45 mm. The length of the hollow tubular element may be between about 20 mm and 40 mm. The length of the hollow tubular element may be about 30 mm.

[0120] The relatively long hollow tubular element provides and defines a relatively long internal cavity within the downstream section of the aerosol-generating article. Providing a relatively long cavity maximizes the nucleation benefits discussed above, thereby improving aerosol formation and cooling.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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).

[0131] 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.

[0132] The wall thickness of the hollow tubular element in the downstream section may 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.

[0133] Keeping the wall thickness of the hollow tubular segment of 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 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, by utilizing a hollow tubular element with a relatively small thickness, it may be expected that the diffusion of the ventilation air can be substantially prevented 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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. By providing a hollow tubular element with such inner diameters, the resistance to withdrawal of the hollow tubular segment may be advantageously reduced.

[0139] For example, the hollow tubular element of the downstream section may 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.

[0140] 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.

[0141] It is particularly preferred that 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.

[0142] 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.

[0143] 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 suitable engagement of the article with the interior of the device. Thus, a cardboard tube may provide adequate resistance to deformation or compression during use.

[0144] The hollow tubular segment may be a paper tube. The hollow tubular segment may be a tube formed from spirally wound paper. The hollow tubular segment may be formed from multiple layers of paper. The paper may have a basis weight of at least 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.

[0145] The hollow tubular segment of the downstream section may comprise a polymeric material. For example, the hollow tubular segment may comprise a polymeric film. The polymeric film may comprise a cellulose film. The hollow tubular segment may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may comprise cellulose acetate tow.

[0146] When the hollow tubular segment 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 of from about 25 to about 40.

[0147] In some embodiments, aerosol-generating articles according to the invention may comprise 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.

[0148] 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.

[0149] The ventilation zone may typically comprise a plurality of perforations through the peripheral wall of the hollow tubular element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. In some embodiments, the ventilation zone may comprise 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 comprises between 8 and 30 perforations.

[0150] 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.

[0151] Providing a mouthpiece element at the downstream end of the aerosol-generating article according to the present invention provides an appealing appearance and mouth feel to the consumer.

[0152] The mouthpiece element may comprise at least one mouthpiece filter segment formed from 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.

[0153] The fibrous filtration material may be for filtering the aerosol generated from the aerosol-generating substrate. Suitable fibrous filtration materials will be known to those skilled in the art. Particularly preferably, the at least one mouthpiece filter segment comprises a cellulose acetate filter segment formed from cellulose acetate tow.

[0154] The mouthpiece element may consist 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.

[0155] The downstream section may comprise an oral end cavity at a downstream end downstream of the mouthpiece element, as described above. The oral end cavity may be defined by a further hollow tubular element located at the downstream end of the mouthpiece. The oral 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.

[0156] The mouthpiece element may optionally include a flavourant, which may be provided in any suitable form, for example, the mouthpiece element may comprise one or more capsules, beads, or granules of flavourant, or one or more flavour-loaded threads or filaments.

[0157] The mouthpiece element, or mouthpiece filter segment thereof, preferably has a low particle filtration efficiency.

[0158] The mouthpiece element is preferably surrounded by a plug wrap. The mouthpiece element is preferably non-ventilated so that air does not enter the aerosol-generating article along the mouthpiece element.

[0159] 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 about 7.2 mm ± 10 percent.

[0160] 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.

[0161] 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 pump air through the entire length of the component. The term "pressure drop" or "draw resistance" of a component or article may also refer to "resistance to draw." Such terms generally refer to measurements in accordance with ISO 6565-2015 normally performed 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.

[0162] The resistance to withdrawal (RTD) of the downstream section is at least about 0 mmH2 The RTD in the downstream section may be at least about 3 mmH 2 The RTD in the downstream section may be at least about 6 mmH 2 It may be O.

[0163] The downstream section RTD is approximately 12 mmH 2 The downstream section RTD may be approximately 11 mmH 2 The downstream section RTD may be approximately 10 mmH 2 It may be O or less.

[0164] The pull-out resistance of the downstream section is approximately 0 mmH 2 O or more, about 12mmH 2 Preferably, the resistance to withdrawal in the downstream section is less than about 3 mmH. 2 O or more, about 12mmH 2 The pull-out resistance of the downstream section may be less than about 0 mmH 2 O or more, approximately 11mmH 2 Even more preferably, the resistance to withdrawal in the downstream section is less than about 3 mmH 2 O or more, about 11mmH 2 Even more preferably, the resistance to withdrawal in the downstream section is less than about 6 mmH 2 O or more, about 10mmH 2 Preferably, the pull resistance in the downstream section is less than about 8 mmH. 2 It may be O.

[0165] The resistance to withdrawal (RTD) characteristics of the downstream section may be entirely or approximately attributable 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.

[0166] The resistance to withdrawal (RTD) of the mouthpiece element is at least about 0 mmH 2The RTD of the mouthpiece element may be at least about 3 mmH 2 The RTD of the mouthpiece element may be at least about 6 mmH. 2 It may be O.

[0167] The RTD of the mouthpiece element is approximately 12mmH 2 The RTD of the mouthpiece element may be about 11 mmH 2 The RTD of the mouthpiece element may be about 10 mmH 2 It may be O or less.

[0168] The mouthpiece element withdrawal resistance is approximately 0mmH 2 O or more, about 12mmH 2 Preferably, the mouthpiece element has a withdrawal resistance of about 3 mmH. 2 O or more, about 12mmH 2 The mouthpiece element may have a withdrawal resistance of about 0 mmH 2 O or more, about 11mmH 2 Even more preferably, the mouthpiece element has a withdrawal resistance of less than about 3 mmH. 2 O or more, about 11mmH 2 Even more preferably, the mouthpiece element has a withdrawal resistance of less than about 6 mmH. 2 O or more, about 10mmH 2 Preferably, the mouthpiece element has a withdrawal resistance of about 8 mmH. 2 It may be O.

[0169] As mentioned 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 from a bundle of cellulose acetate fibers having about 10 to about 15 denier per filament. For example, the mouthpiece element may be formed from a relatively low density cellulose acetate tow, such as a cellulose acetate tow containing fibers of about 12 denier per filament.

[0170] The mouthpiece element may be a solid plug of fibrous filtration material, such as a solid plug of cellulose acetate tow.

[0171] The mouthpiece element may be made of a polylactic acid-based material. The mouthpiece element may be made 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 a specific and complex cross-sectional profile that may include multiple relatively large airflow channels extending through the material of the mouthpiece element, providing suitable RTD characteristics.

[0172] The mouthpiece element may be formed from a sheet of suitable material that is crimped, pleated, assembled, woven, or folded into an element that defines a plurality of longitudinally extending channels. Such a sheet of suitable material may be formed from paper, cardboard, a polymer such as polylactic acid, or any other cellulosic, paper, or bioplastic-based material. The cross-sectional profile of such a mouthpiece element may exhibit randomly oriented channels.

[0173] 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 a suitable material. Therefore, it is preferred that the pressure drop (or RTD) from the upstream end of the mouthpiece element to the downstream end of the mouthpiece element is low.

[0174] The length of the mouthpiece element may be at least about 1.5 millimeters. The length of the mouthpiece element may be at least about 2 millimeters. The length of the mouthpiece element may be about 7 millimeters or less. The length of the mouthpiece element may be about 4 millimeters or less. For example, the length of the mouthpiece element may be between about 1.5 millimeters and about 7 millimeters. The length of the mouthpiece element may be between about 2 millimeters and about 4 millimeters.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] In embodiments in which 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 equal to 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.

[0182] 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.

[0183] For example, the ratio of the length of the hollow tubular element to the length of the mouthpiece element may be from about 1.5 to about 20, or from about 5 to about 15, or from about 7.5 to about 10.

[0184] Preferably, the overall length of the downstream section is at least about 15 millimeters, more preferably at least about 20 millimeters, and even more preferably at least about 25 millimeters.

[0185] 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.

[0186] For example, the downstream section may 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] In certain embodiments of the invention, one or more of the components of the aerosol-generating article are individually surrounded by their own wrapper.

[0197] The aerosol-generating substrate and downstream section are preferably combined together with an outer wrapper, such as a tipping wrapper.

[0198] The components of the aerosol-generating article according to the present invention are preferably made from biodegradable materials.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] An electrically operated aerosol generating system comprising an induction 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 operated aerosol generating systems comprising an induction heating device and an aerosol-generating article having a susceptor are described in WO 95 / 27411 and WO 2015 / 177255.

[0203] 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 flavorings in the particulate plant material, to form an aerosol. Optionally, to assist in the vaporization of the compounds in 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.

[0204] 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.

[0205] [Example] 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.

[0206] Example 1. 1. An aerosol-generating article comprising: an aerosol-generating substrate comprising a hollow tubular substrate element having a peripheral wall defining a longitudinal airflow channel extending between upstream and downstream ends of the hollow tubular substrate element, the peripheral wall being formed from one or more layers of homogenized plant material; a sealing element at the upstream end of the hollow tubular substrate element; and a downstream section located downstream of the aerosol-generating substrate. Example 2. 2. The aerosol-generating article of example 1, wherein the sealing element is disposed to provide an airtight seal at an upstream end of the longitudinal airflow channel. Example 3. 3. The aerosol-generating article of example 1 or 2, wherein the sealing element comprises a film layer. Example 4. The aerosol-generating article of example 3, wherein the film layer is penetrable. Example 5. 5. The aerosol-generating article of any one of claims 3 to 4, wherein the film layer comprises one or more polymeric layers. Example 6. The aerosol-generating article of example 5, wherein the one or more polymeric layers are formed of polyethylene terephthalate (PET), low density and high density polyethylene (LDPE and HDPE, respectively), polypropylene (PP), polyvinyl chloride (PVC), polyamide, polyolefin, polystyrene, ethylene vinyl alcohol copolymer, or combinations thereof. Example 7. 7. An aerosol-generating article according to any one of Examples 3 to 6, wherein the film layer comprises one or more metal layers. Example 8. The aerosol-generating article of example 7, wherein the film layer comprises one or more layers of aluminum. Example 9. An aerosol-generating article according to any one of Examples 3 to 8, wherein the film layer is heat welded to the peripheral wall of the hollow tubular substrate element. Example 10. The aerosol-generating article of example 1 or 2, wherein the closure element comprises a paper wrapper. Example 11. 11. The aerosol-generating article of example 10, wherein the paper wrapper is folded over the upstream end of the hollow tubular substrate element. Example 12. 12. The aerosol-generating article of any one of Examples 10 to 11, wherein the paper wrapper is provided with an impermeable covering layer. Example 13. The aerosol-generating article of example 12, wherein the paper wrapper is coated with wax. Example 14. 14. An aerosol-generating article according to any one of Examples 1 to 13, wherein the sealing element is affixed to the upstream end of the hollow tubular substrate element by a layer of adhesive. Example 15. An aerosol-generating article according to any one of Examples 1 to 14, wherein the sealing element extends from the upstream end downstream at least part way along the outer surface of the peripheral wall of the hollow tubular substrate element. Example 16. 16. The aerosol-generating article of example 15, wherein the sealing element extends at least 2 millimeters downstream from the upstream end along the outer surface of the peripheral wall. Example 17. The aerosol-generating formulation of Example 15 or 16, further comprising a fastening band extending circumferentially around the hollow tubular substrate element and over a portion of the sealing element extending downstream from the upstream end of the hollow tubular substrate element, the fastening band being affixed to an outer surface of the hollow tubular substrate element. Example 18. The aerosol-generating article of Example 17, wherein the fixing band is a paper band. Example 19. 19. The aerosol-generating article of example 17 or 18, wherein the fixing band has a length of at least 2 millimeters. Example 20. An aerosol-generating article as described in any one of Examples 1 to 19, wherein the longitudinal airflow channel has a diameter of at least 3 millimeters. Example 21. An aerosol-generating article according to any of Examples 1 to 20, wherein the hollow tubular substrate element comprises at least two overlapping layers of homogenized plant material. Example 22. An aerosol-generating article as described in any of Examples 1-21, wherein the hollow tubular substrate element comprises up to 10 overlapping layers of homogenized plant material. Example 23. An aerosol-generating article according to any one of Examples 1 to 22, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least about 0.3. Example 24. An aerosol-generating article according to any one of Examples 1 to 23, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least about 0.7. Example 25. An aerosol-generating article according to any one of Examples 1 to 24, wherein the peripheral wall of the hollow tubular substrate element has a density of at least 200 milligrams per cubic centimeter. Example 26. An aerosol-generating article according to any one of Examples 1 to 25, wherein the peripheral wall of the hollow tubular substrate element has a density of less than 1 gram per cubic centimeter. Example 27. An aerosol-generating article as described in any of Examples 1-26, wherein the peripheral wall of the hollow tubular substrate element provides at least 150 milligrams of homogenized plant material per centimeter of hollow tubular substrate length. Example 28. An aerosol-generating article according to any one of Examples 1 to 27, wherein the hollow tubular substrate element has a longitudinal tensile strength of between 11 kNewtons / meter and 14 kNewtons / meter. Example 29. An aerosol-generating article according to any one of Examples 1 to 28, wherein the hollow tubular substrate element has an axial compressive strength of 7 MPa to 9 MPa. Example 30. An aerosol-generating article according to any one of Examples 1 to 29, wherein the hollow tubular substrate element has a radial compressive strength of 7 MPa to 9 MPa. Example 31. An aerosol-generating article according to any one of Examples 1 to 30, wherein the hollow tubular substrate element has a length of up to 40 millimeters. Example 32. An aerosol-generating article according to any one of Examples 1 to 31, wherein the hollow tubular substrate element has a length of at least 10 millimeters. Example 33. An aerosol-generating article according to any of Examples 1 to 32, 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 34. An aerosol-generating article according to any one of Examples 1 to 33, 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 35. An aerosol-generating article according to any one of Examples 1 to 34, wherein the hollow tubular substrate element has an outer diameter of at least 4 millimeters. Example 36. 36. An aerosol-generating article according to any preceding claim, wherein the hollow tubular substrate element has an outer diameter of up to 9 millimetres. Example 37. An aerosol-generating article as described in any of Examples 1-36, wherein the hollow tubular substrate element provides an unrestricted flow channel. Example 38. An aerosol-generating article as described in any one of Examples 1-37, wherein the longitudinal airflow channel of the hollow tubular substrate element has a diameter of up to 7 millimeters. Example 39. An aerosol-generating article according to any one of Examples 1 to 38, wherein the ratio of the inner diameter to the outer diameter of the hollow tubular substrate element is at least 0.4. Example 40. An aerosol-generating article according to any one of Examples 1 to 39, wherein the peripheral wall has a thickness of at least 1 millimeter. Example 41. An aerosol-generating article as described in any one of Examples 1 to 40, wherein the peripheral wall has a wall thickness of up to 2.25 millimeters. Example 42. An aerosol-generating article as described in any of Examples 1-41, wherein the multiple layers of homogenized plant material are spirally wound around the longitudinal axis of the hollow tubular substrate element. Example 43. An aerosol-generating article as described in any one of Examples 1 to 42, wherein the hollow tubular substrate element further comprises an adhesive for sealing adjacent layers to one another. Example 44. An aerosol-generating article as described in any of Examples 1-43, wherein the homogenized plant material is a homogenized tobacco material having a tobacco content of at least 40 percent by weight on a dry weight basis. Example 45. The aerosol-generating article of any one of Examples 1 to 44, wherein the homogenized plant material further comprises one or more aerosol formers. Example 46. An aerosol-generating article according to any one of Examples 1 to 45, wherein the hollow tubular substrate element comprises one or more susceptor elements positioned in contact with a peripheral wall thereof. Example 47. 47. The aerosol-generating article of Example 46, wherein the hollow tubular substrate element comprises one or more susceptor elements on a surface of a peripheral wall. Example 48. 47. The aerosol-generating article of Example 46, wherein the hollow tubular substrate element comprises a tubular susceptor element disposed on at least one surface of a peripheral wall thereof. Example 49. An aerosol-generating article as described in any one of Examples 1 to 48, wherein the downstream section comprises a hollow tubular element. Example 50. 50. The aerosol-generating article of embodiment 49, wherein the length of the hollow tubular element in the downstream section is between 12 mm and 50 mm. Example 51. 51. The aerosol-generating article of example 49 or 50, 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 52. 52. An aerosol-generating article according to any one of Examples 49 to 51, 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 53. An aerosol-generating article described in any of Examples 49 to 52, 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 54. An aerosol-generating article according to any one of Examples 49 to 53, 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 55. An aerosol-generating article described in any of Examples 49 to 54, 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 56. An aerosol-generating article described in any of Examples 49 to 55, 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 57. An aerosol-generating article described in any of Examples 49 to 56, wherein the wall thickness of the hollow tubular element in the downstream section is at least 100 micrometers. Example 58. An aerosol-generating article described in any of Examples 49 to 57, wherein the wall thickness of the hollow tubular element in the downstream section is 2 millimeters or less. Example 59. An aerosol-generating article described in any of Examples 49 to 58, wherein the hollow tubular element of the downstream section has an inner diameter of 2 millimeters to 10 millimeters. Example 60. 60. An aerosol-generating article according to any one of Examples 49 to 59, 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 61. An aerosol-generating article described in any one of Examples 1 to 60, wherein the downstream section further comprises a mouthpiece element. Example 62. An aerosol-generating article as described in Example 61, wherein the mouthpiece element comprises at least one segment of fibrous filtration material. Example 63. An aerosol-generating article as described in Example 61 or 62, wherein the downstream section comprises an oral end cavity at a downstream end downstream of the mouthpiece element. Example 64. The downstream section RTD is 12 mm H 2 The aerosol-generating article according to any one of Examples 1 to 63, wherein the aerosol concentration is O or less. Example 65. An aerosol-generating article as described in any one of Examples 1 to 64, wherein the length of the downstream section is 20 millimeters to 50 millimeters. Example 66. An aerosol-generating article according to any one of Examples 1 to 65, 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 67. An aerosol-generating article according to any one of Examples 1 to 66, wherein a component of the aerosol-generating article is made from a biodegradable material.

[0207] Specific embodiments will now be described further, by way of example only, with reference to the accompanying drawings, in which:

[0208] 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 substantially coincides with the upstream end of the aerosol-generating substrate 12, to a downstream or oral end 18, which coincides with the downstream end of the downstream section 14. The downstream section 14 comprises a hollow tubular element 20 and a mouthpiece element 50.

[0209] The aerosol-generating article 10 has an overall length of about 45 millimeters and an outer diameter of about 7.2 mm.

[0210] The aerosol-generating substrate 12 comprises a hollow tubular substrate element 40 formed from multiple layers of homogenized tobacco material helically wound about the longitudinal axis of the hollow tubular substrate element. 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 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.

[0211] The sealing element 24 is mounted on the upstream end of the hollow tubular substrate element 40. The sealing element 24 is affixed to the upstream face of the peripheral wall 42 and provides an airtight seal over the upstream end of the longitudinal airflow channel 44 so that air cannot be drawn into the longitudinal airflow channel through the upstream opening. The sealing element 24 is formed of a single layer of polymeric film.

[0212] When sealing element 24 is in place, longitudinal airflow is not permitted to pass through article 10. Instead, during use, air is drawn transversely through porous peripheral wall 42 into longitudinal airflow channels 44, where it mixes with the aerosol and is drawn out the downstream end of article 10.

[0213] The sealing element 24 has the ability to be pierced or perforated, if desired, by a suitable element within the heating cavity of the aerosol generating device. Once the sealing element is perforated, longitudinal airflow is permitted to pass through the longitudinal airflow channel 44. Thus, air can be drawn through the perforated upstream element 24 and longitudinally through the hollow tubular substrate element 40.

[0214] 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.

[0215] 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 approximately 0 mmH 2 It is O.

[0216] 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 .

[0217] 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).

[0218] 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 the upstream portion of the hollow tubular substrate element 40 to join the hollow tubular substrate element 40 and the downstream section 14.

[0219] 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 a 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.

[0220] 2 shows an aerosol-generating article 110 according to a second embodiment of the present invention. The aerosol-generating article 110 has a similar structure to the aerosol-generating article 10 of FIG. 1, as described above, with the same components. However, the aerosol-generating article 110 further comprises a paper band 26 surrounding the hollow tubular substrate element 20 at its upstream end. The paper band 26 extends approximately 3 millimeters from the upstream end of the hollow tubular substrate element 20 and is made of standard tipping paper material. The paper band is adhered to the outside of the hollow tubular substrate element 20 by a suitable adhesive. The paper band 26 helps to hold the sealing element 24 in place at the upstream end of the hollow tubular substrate element 20 and provides a more uniform appearance.

[0221] FIG. 3 shows an aerosol generating system 100 comprising an aerosol generating device 102 and an aerosol generating article 10 according to a first embodiment of the invention, as described above.

[0222] The aerosol generating device 102 comprises a longitudinal heating cavity 104 for receiving an aerosol-generating article 210, as shown in Figure 3. 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 so that air may be drawn through the aerosol-generating article 210 during use. The heating cavity 104 includes an arrangement of peripheral heating elements 108 for externally heating the hollow tubular substrate element of the aerosol-generating article 10 during use.

[0223] 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 210 is received within the device 102.

[0224] As shown in Figure 3, the aerosol-generating article 10 is inserted into the heating cavity 104 with the sealing element 24 remaining unaffected over the upstream end of the hollow tubular substrate element 40. Thus, longitudinal airflow is prevented from passing through the longitudinal airflow channel 44. Instead, air entering the heating cavity 104 through the airflow inlet 106 is drawn transversely through the peripheral wall 42 of the hollow tubular substrate element 40 and into the longitudinal airflow channel 44. This advantageously helps to draw aerosol generated from the layered homogenized tobacco material within the peripheral wall 42 into the longitudinal airflow channel 44.

Claims

1. An aerosol-generating article comprising: an aerosol-generating substrate comprising a hollow tubular substrate element having a peripheral wall defining a longitudinal airflow channel extending between an upstream end and a downstream end of the hollow tubular substrate element, the peripheral wall being formed from one or more layers of homogenized plant material; a sealing element at the upstream end of the hollow tubular substrate element, the sealing element being arranged to establish a substantially airtight seal at the upstream end of the longitudinal airflow channel; a downstream section located downstream of the aerosol-generating substrate.

2. 2. The aerosol-generating article of claim 1, wherein the sealing element comprises a film layer applied to the peripheral wall at the upstream end of the hollow tubular substrate element.

3. 3. The aerosol-generating article of claim 2, wherein the film layer is penetrable.

4. 4. The aerosol-generating article of claim 2 or 3, wherein the film layer comprises one or more polymer layers.

5. 4. The aerosol-generating article according to claim 2 or 3, wherein the film layer comprises one or more metal layers.

6. 4. The aerosol-generating article of claim 2 or 3, wherein the film layer is heat-sealed to the peripheral wall of the hollow tubular substrate element.

7. 2. The aerosol-generating article of claim 1, wherein the sealing element comprises a paper wrapper folded over the upstream end of the hollow tubular substrate element.

8. 8. The aerosol-generating article of claim 7, wherein the paper wrapper is provided with an impermeable coating layer.

9. 4. The aerosol-generating article according to claim 1, wherein the sealing element is affixed to the upstream end of the hollow tubular substrate element by a layer of adhesive.

10. 4. An aerosol-generating article according to claim 1, wherein the sealing element extends downstream from the upstream end at least part way along the outer surface of the peripheral wall of the hollow tubular substrate element.

11. 11. The aerosol-generating article of claim 10, further comprising a securing band extending circumferentially around the hollow tubular substrate element and overlying a portion of the sealing element extending downstream from the upstream end of the hollow tubular substrate element, the securing band being affixed to an outer surface of the hollow tubular substrate element.

12. 12. The aerosol-generating article according to claim 11, wherein the fixing band is a paper band.

13. 4. An aerosol-generating article according to claim 1, wherein the longitudinal airflow channel has a length of at least 3 millimeters.

14. 4. An aerosol-generating article according to claim 1, wherein the peripheral wall of the hollow tubular substrate element has a cross-sectional porosity of at least 0.

3.

15. 4. An aerosol-generating article according to claim 1, wherein the aerosol-generating substrate comprises a tubular susceptor element on at least one surface of the hollow tubular substrate element.

Images