Aerosol-generating article with low withdrawal resistance

Abstract

An aerosol-generating article (10) for generating an inhalable aerosol upon heating is provided, the aerosol-generating article (10) comprising: an aerosol-generation section (52) extending from a downstream end (20) to an upstream end (18) and comprising a rod of aerosol-generating substrate (12); a mouthpiece section (46) comprising a mouthpiece filter segment (42) formed of a fibrous filtration material; and an intermediate hollow section (50) defining a longitudinal cavity providing an unrestricted flow channel from the aerosol-generation section (52) to a mouthpiece section (64). The mouthpiece section has a length L1 extending between the upstream end (62) of the mouthpiece filter segment (42) and the downstream end (20) of the aerosol-generating article. The intermediate hollow section (50) has a length L2 extending between the downstream end of the aerosol-generation section (52) and the upstream end of the mouthpiece section. The intermediate hollow section (50) includes an aerosol-cooling segment (24) downstream of the aerosol-generation section (52) and a support segment (22) between the aerosol-cooling segment (24) and the aerosol-generation section (52). The length (L1) of the mouthpiece section (46) is at least 0.10 times and less than 0.34 times the length (L2) of the intermediate hollow section (50).

Description

[Technical Field]

[0001] The present invention relates to an aerosol-generating article comprising an aerosol-generating substrate and 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 combusted are known in the art. Typically, in such heated smoking articles, the aerosol is generated by transferring heat from a heat source to a physically separated aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0003] Consumables that are solid substrates in the form of gels or films containing nicotine that are heated rather than combusted are known in the art. For example, International Patent Publication No. 2018 / 019543 discloses a thermoreversible gel composition, i.e., a gel that becomes fluid when heated to a melting temperature and solidifies again into a gel at a gelling temperature. The gel is provided in a cartridge housing, and the cartridge may be discarded and replaced when the gel is consumed. WO 2020 / 207733 discloses a consumable product comprising a rod of aerosol-generating substrate having multiple stacked layers of aerosol-generating film. During use, most of the film's components evaporate upon heating, minimizing residue and allowing for easier disposal and reduced environmental impact.

[0004] 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 aerosols are generated by heat transfer from one or more electric heater elements of the aerosol generating device to an aerosol-generating substrate of the heated aerosol-generating article. For example, an electrically heated aerosol generating device has been proposed that includes an internal heater blade adapted to be inserted into the aerosol-generating substrate. Alternatively, WO 2015 / 176898 proposes an inductively heated aerosol-generating article that includes an aerosol-generating substrate and a susceptor disposed within the aerosol-generating substrate. A further alternative is described in WO 2020 / 115151, which discloses an aerosol-generating article used in combination with an external heating system that includes one or more heating elements disposed around the outer surface of the aerosol-generating article. For example, the external heating element can be provided in the form of a flexible heating foil on a dielectric substrate such as polyimide. The external heating can be resistive or inductive. Summary of the Invention [Problem to be solved by the invention]

[0005] Aerosol-generating articles in which the tobacco-containing substrate is heated rather than combusted present several challenges not faced with conventional smoking articles.

[0006] First, tobacco-containing substrates are typically heated to significantly lower temperatures than those reached by the combustion front of conventional cigarettes. This can affect nicotine release from the tobacco-containing substrate and nicotine delivery to the consumer. At the same time, when heating temperatures are increased in an attempt to enhance nicotine delivery, the aerosol generated typically needs to be cooled more extensively and more quickly before reaching the consumer. However, technical solutions commonly used to cool mainstream smoke in conventional smoking articles, such as providing a high-filtration efficiency segment at the tobacco mouth end, can have undesirable effects in aerosol-generating articles where the tobacco-containing substrate is heated rather than combusted, potentially reducing nicotine delivery.

[0007] To address one or more of the challenges, particularly relating to heating rather than combustion, of an aerosol-generating substrate to generate an aerosol, a number of aerosol-generating articles have been proposed in which multiple elements are combined, for example in longitudinal alignment, with an aerosol-generating element comprising the aerosol-generating substrate. By way of example, the aerosol-generating element may be combined with a support element that imparts improved structural strength to the article, an aerosol-cooling element configured to reduce the temperature of the aerosol, a low-filtration mouthpiece element, etc.

[0008] Generally, there is a need for aerosol-generating articles that are easier to use and have improved practicality. Furthermore, it would be desirable to provide aerosol-generating articles that are easier to manufacture, making the entire production chain more sustainable and cost-effective. There is also a need for aerosol-generating articles that are particularly suitable for use in combination with external heating systems, and in particular aerosol-generating articles that have improved aerosol generation and aerosol former delivery. There is also a need to provide such aerosol-generating articles that are easier to dispose of after use or that have a reduced impact on the environment.

[0009] Heating substrates containing cellulose-based materials, particularly hydroxypropyl methylcellulose (HPMC), to excessively high temperatures, e.g., above 300 degrees Celsius, can lead to the generation of off-taste paper and formaldehyde. However, heating such substrates to lower temperatures reduces the level of harmful and potentially harmful compounds (HPHCs) generated while also reducing the aerosolization of the aerosol former and nicotine. In addition, compared to gel-like substrates, which may contain a relatively high weight of aerosol former, film substrates contain a relatively high weight of cellulose-based material, which, together with a lower weight of aerosol former, provides structure to the film. The low weight of aerosol former used in film substrates also reduces the delivery efficiency of the aerosol former and nicotine compared to gel-like substrates. There is a need to provide an aerosol-generating article that includes an aerosol former and a film substrate that enables efficient delivery of nicotine.

[0010] It would therefore be desirable to provide new and improved aerosol-generating articles configured to meet at least one of the above needs. It would further be desirable to provide aerosol-generating articles that enable efficient delivery of nicotine and / or aerosol formers, such as glycerin, while maintaining low levels of HPHCs or even reducing HPHCs. It would further be desirable to provide aerosol-generating articles that can be manufactured efficiently and rapidly, preferably with sufficiently low RTD variability between products. [Brief explanation of the drawings]

[0011] [Figure 1] 1 shows a schematic cross-sectional side view of an aerosol-generating article according to the present invention. [Figure 2] 1 shows a schematic cross-sectional side view of an aerosol-generating article according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure relates to an aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article extending from an upstream end to a downstream end. The aerosol-generating article includes an aerosol-generation section including a rod of an aerosol-generating substrate. The aerosol-generating article may further include a mouthpiece section including a mouthpiece filter segment formed of a fibrous filtration material, the mouthpiece section having a length L1 extending between the upstream end of the mouthpiece filter segment and the downstream end of the aerosol-generating article. The aerosol-generating article may include an intermediate hollow section having a length L2 extending between the aerosol-generation section and the mouthpiece section, the intermediate hollow section defining a longitudinal cavity providing an unrestricted flow channel from the aerosol-generation section to the mouthpiece section. The intermediate hollow section may include an aerosol-cooling segment downstream of the aerosol-generation section. The intermediate hollow section may further include a support segment between the aerosol-cooling segment and the aerosol-generation section. The length of the mouthpiece section (L1) may be at least 0.10 times and less than 0.40 times the length of the intermediate hollow section (L2).

[0013] According to the present invention, there is provided an aerosol-generating article for generating an inhalable aerosol when heated, the aerosol-generating article comprising: an aerosol-generation section extending from an upstream end to a downstream end and including a rod of aerosol-generating substrate; a mouthpiece section including a mouthpiece filter segment formed of a fibrous filtration material, the mouthpiece section having a length L1 extending between the upstream end of the mouthpiece filter segment and the downstream end of the aerosol-generating article; and an intermediate hollow section having a length L2 extending between the aerosol-generation section and the mouthpiece section, the intermediate hollow section defining a longitudinal cavity providing an unrestricted flow channel from the aerosol-generation section to the mouthpiece section. The intermediate hollow section includes an aerosol-cooling segment downstream of the aerosol-generation section and a support segment between the aerosol-cooling segment and the aerosol-generation section. According to the present invention, the length of the mouthpiece section (L1) is at least 0.10 times but less than 0.40 times the length of the intermediate hollow section (L2).

[0014] According to the present invention, there is provided an aerosol-generating article for generating an inhalable aerosol upon heating. The aerosol-generating article comprises three sections: an aerosol-generation section, an intermediate hollow section downstream of the aerosol-generation section, and a mouthpiece section downstream of the intermediate hollow section. The aerosol-generating article comprises an aerosol-generation section including a rod of aerosol-generating substrate.

[0015] As used herein, the term "aerosol-generating article" refers to an article that heats an aerosol-generating substrate to generate an inhalable aerosol for delivery to a consumer. As used herein, the term "aerosol-generating substrate" refers to a substrate that has the ability to generate an aerosol by releasing a volatile compound upon heating.

[0016] The aerosol-generating article of the present invention optionally includes an aerosol-generating film. Such substrates are designed to be heated to relatively low temperatures, i.e., temperatures below approximately 300°C, to minimize the level of formaldehyde generated and avoid the off-taste of paper. Heating a substrate such as an aerosol-generating film to a lower temperature reduces the level of HPHC generated, but also reduces the aerosolization of the aerosol former and nicotine. In addition, compared to gel-type substrates, the aerosol-generating film contains a relatively high weight of cellulosic material, which, together with a low weight of aerosol former, provides structure to the film. The low weight of aerosol former reduces the delivery efficiency of the aerosol former and nicotine in the film substrate compared to gel-type substrates. The aerosol-generating article of the present invention, optionally including an aerosol-generating film substrate, allows for efficient delivery of not only the aerosol former but also nicotine to the consumer due to relatively low filtration and low RTD in downstream sections, including the intermediate hollow section and mouthpiece section, compared to conventional aerosol-generating articles.

[0017] A conventional cigarette is lit when a user applies a flame to one end of the cigarette and draws air through the other end. Localized heat provided by the flame and oxygen in the air drawn through the cigarette ignites the end of the cigarette, and the resulting combustion produces inhalable smoke. In contrast, in heated aerosol-generating articles, the aerosol is generated by heating a flavor-generating substrate (such as tobacco). Known heated aerosol-generating articles include, for example, electrically heated aerosol-generating articles and aerosol-generating articles in which the aerosol is generated by heat transfer from a combustible fuel element or heat source to a physically separated aerosol-forming material. For example, aerosol-generating articles find particular application in aerosol generation systems that include an electrically heated aerosol generator having an internal heater blade adapted to be inserted into a rod of an aerosol-generating substrate. Aerosol-generating articles of this type are described in the prior art, for example, in EP 0 822 670.

[0018] As used herein, the term "aerosol-generating device" refers to a device that includes a heater element that interacts with an aerosol-generating substrate of an aerosol-generating article to generate an aerosol. During use, volatile compounds are released from the aerosol-generating substrate by heat transfer and become entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol, which is inhaled by the consumer.

[0019] The aerosol-generating element may be in the form of a rod comprising or made from an aerosol-generating substrate. As used herein in connection with the present invention, the term "rod" is used to denote a generally cylindrical element of substantially circular, oval or elliptical cross section.

[0020] As used herein, the term "longitudinal" refers to a direction corresponding to the major longitudinal axis of the aerosol-generating article extending between the upstream and downstream ends of the aerosol-generating article. As used herein, the terms "upstream" and "downstream" refer to the relative positions of elements (or portions of elements) of the aerosol-generating article with respect to the direction in which aerosol is transported through the aerosol-generating article during use.

[0021] As used herein, the term "upstream end of the aerosol-generating article" refers to the distal end of the aerosol-generating article.

[0022] As used herein, the term "downstream end of the aerosol-generating article" refers to the mouth end of the aerosol-generating article.

[0023] During use, air is drawn longitudinally through the aerosol-generating article. The term "transverse" refers to a direction perpendicular to the longitudinal axis. Any reference to a "cross section" of an aerosol-generating article or a component of an aerosol-generating article refers to a transverse cross section, unless otherwise specified.

[0024] The term "length" refers to the dimension of a component of an aerosol-generating article in its longitudinal direction. For example, it may be used to refer to the dimension of a rod or elongated tubular element in its longitudinal direction.

[0025] 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 terms "pressure drop" or "draw resistance" of a component or article can also refer to "resistance to draw." These terms generally refer to measurements in accordance with ISO 6565-2015 being performed successfully 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.

[0026] The aerosol-generating article according to the present invention provides an improved configuration of elements downstream of the aerosol-generation section, defined by a ratio of the length of the mouthpiece section to the length of the intermediate hollow section of at least 0.10 and less than 0.40. This ratio reflects a configuration in which a relatively short mouthpiece section is provided in combination with a longer intermediate hollow section than previously provided. In a particularly preferred embodiment of the present invention, the improved configuration provides a relatively short mouthpiece section in combination with a longer aerosol-cooling segment than previously provided.

[0027] It has been discovered that by increasing the distance between the aerosol-generating section and the mouthpiece section while simultaneously shortening the length of the mouthpiece section, it is possible to provide a product with a lower resistance to withdrawal (RTD) of the mouthpiece section. This can improve aerosol delivery and efficiently deliver nicotine and glycerin while maintaining low or even reduced levels of HPHCs. Furthermore, shortening the mouthpiece section reduces the amount of plasticizer used in the manufacture of the mouthpiece section, improving the sustainability of the product. Advantageously, these benefits can be provided without affecting the overall length of the article, allowing the overall length to be consistent with existing aerosol-generating articles.

[0028] The increased length of the intermediate hollow section relative to the mouthpiece section may be advantageously provided by increasing the length of the aerosol cooling segment, as described in more detail below.

[0029] According to the present invention, an aerosol-generating article is provided for generating an inhalable aerosol upon heating.

[0030] The aerosol-generating article includes an aerosol-generation section including a rod of aerosol-generating substrate. The aerosol-generation section may further include one or more upstream segments located upstream of the rod of aerosol-generating substrate. In some embodiments, the aerosol-generation section may further include an upstream segment located immediately upstream of the rod of aerosol-generating substrate. The aerosol-generation section may further include one or more solid segments that abut the rod of aerosol-generating substrate to form a continuous solid section. For example, a filter segment formed of a fibrous filtering material and abutting the rod of aerosol-generating substrate may be part of the aerosol-generation section. Such a solid segment may abut the rod of aerosol-generating substrate at a position upstream or downstream of the rod of aerosol-generating substrate.

[0031] The aerosol-generating section extends from the upstream end of the aerosol-generating article to either the rod of aerosol-generating substrate or the downstream end of any solid segment that abuts the rod of aerosol-generating substrate downstream of the rod of aerosol-generating substrate to form a continuous solid section.

[0032] The aerosol-generating article further comprises a downstream section located downstream of the aerosol-generation section, the downstream section including an intermediate hollow section and a mouthpiece section.

[0033] In an aerosol-generating article according to the present invention, the mouthpiece section includes a mouthpiece filter segment, and the mouthpiece section extends from the upstream end of the mouthpiece filter segment to the downstream end of the aerosol-generating article.

[0034] The downstream section further includes an intermediate hollow section between the mouthpiece section and the aerosol-generation section. The intermediate hollow section (50) has a length L2 extending between the downstream end of the aerosol-generation section (52) and the upstream end of the mouthpiece section. The intermediate hollow section includes a support segment and an aerosol-cooling segment. The aerosol-cooling segment includes a hollow tubular segment. The support segment may also include a hollow tubular segment.

[0035] As used herein, the term "hollow tubular segment" 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 segment that has a substantially cylindrical cross-section and defines at least one airflow conduit that establishes uninterrupted fluid communication between an upstream end of the tubular segment and a downstream end of the tubular segment. However, it will be appreciated that alternative shapes (e.g., alternative cross-sectional shapes) of the tubular segment may be possible.

[0036] As used herein, the term "elongated" means that an element has a length dimension that is greater than its width dimension or its diameter dimension, e.g., more than twice its width dimension or its diameter dimension.

[0037] In the context of the present invention, the hollow tubular segment provides an unrestricted flow channel. This means that the hollow tubular segment provides a negligible level of resistance to withdrawal (RTD). Therefore, the flow channel should not include any components that would obstruct the longitudinal air flow. Preferably, the flow channel is substantially empty.

[0038] In some embodiments, the aerosol-generating article may include a ventilation zone at a location along the intermediate hollow section. More particularly, the aerosol-generating article may include a ventilation zone at a location along the aerosol-cooling segment. In a preferred embodiment, the aerosol-cooling segment includes or is in the form of a hollow tubular segment, and the ventilation zone is provided at a location along the hollow tubular segment of the aerosol-cooling element.

[0039] The aerosol-generating article may further comprise a susceptor element within the aerosol-generating substrate. In some embodiments, the susceptor element may be an elongated susceptor element. In a preferred embodiment, the susceptor element extends longitudinally within the aerosol-generating substrate.

[0040] These elements of the aerosol-generating article are described in more detail below.

[0041] As defined above, the mouthpiece section of the aerosol-generating article of the present invention comprises a mouthpiece filter segment. In certain embodiments of the present invention, the mouthpiece section may comprise an oral-end cavity at the downstream end of the mouthpiece section, downstream of the mouthpiece filter segment. The mouthpiece section may comprise an oral-end cavity at the downstream end of the aerosol-generating article.

[0042] The mouthpiece filter segment is preferably located at the downstream end of the aerosol-generating article. The mouthpiece filter segment comprises a fibrous filter material for filtering the aerosol generated from the aerosol-generating substrate. Suitable fibrous filter materials will be known to those skilled in the art. Particularly preferably, at least one mouthpiece filter segment comprises a cellulose acetate filter segment formed from cellulose acetate tow.

[0043] In certain preferred embodiments, the mouthpiece section consists of a single mouthpiece filter segment. In alternative embodiments, the mouthpiece section includes two or more mouthpiece filter segments axially aligned in end-to-end relationship with one another.

[0044] In certain embodiments of the present invention, the mouthpiece section may include an oral end cavity at its downstream end, downstream of the mouthpiece filter segment as described above. The oral end cavity may be defined by a hollow tubular segment provided at the downstream end of the mouthpiece section. Alternatively, the oral end cavity may be defined by an outer wrapper of the mouthpiece section, the outer wrapper extending downstream from the mouthpiece filter segment.

[0045] The mouthpiece filter segment may optionally include a flavorant, which may be provided in any suitable form, for example, the mouthpiece filter segment may include one or more capsules, beads, or granules of flavorant, or one or more flavor-loaded threads or filaments.

[0046] According to the present invention, the intermediate hollow section of the aerosol-generating article further comprises a support segment located immediately downstream of the aerosol-generation section. Preferably, the support segment is located immediately downstream of the rod of the aerosol-generating substrate. The mouthpiece section is preferably located downstream of the support segment. The intermediate hollow section further comprises an aerosol-cooling segment located immediately downstream of the support segment. The mouthpiece section is preferably located downstream of both the support segment and the aerosol-cooling segment. Particularly preferably, the mouthpiece section is located immediately downstream of the aerosol-cooling segment. As an example, a mouthpiece filter segment may abut the downstream end of the aerosol-cooling segment.

[0047] The mouthpiece filter segment preferably has a low particle filtration efficiency.

[0048] The mouthpiece section is preferably surrounded by plug wrap. Preferably, the mouthpiece section is non-ventilated so that air does not enter the aerosol-generating article along the mouthpiece section.

[0049] The mouthpiece section is preferably connected to one or more of the adjacent upstream components of the aerosol-generating article by a tipping wrapper.

[0050] Preferably, the mouthpiece section has an RTD of less than about 10 millimeters HO. More preferably, the mouthpiece section has an RTD of less than about 9 millimeters HO. Even more preferably, the mouthpiece section has an RTD of less than about 8 millimeters HO.

[0051] Preferably, the mouthpiece section has an RTD of at least less than about 1 millimeter of HO. More preferably, the mouthpiece section has an RTD of at least less than about 2 millimeters of HO. Even more preferably, the mouthpiece section has an RTD of at least less than about 5 millimeters of HO.

[0052] RTD values ​​of about 1 millimeter HO to about 10 millimeters HO are particularly preferred because a mouthpiece section having such an RTD is expected to make only a minimal contribution to the overall RTD of the aerosol-generating article and will not substantially filter the aerosol delivered to the consumer.

[0053] In a preferred embodiment, the mouthpiece section consists of a single mouthpiece filter segment. Preferably, the mouthpiece filter segment has an RTD of less than about 10 millimeters of HO. More preferably, the mouthpiece filter segment has an RTD of less than about 9 millimeters of HO. Even more preferably, the mouthpiece filter segment has an RTD of less than about 8 millimeters of HO.

[0054] Preferably, the mouthpiece filter segment has an RTD of at least less than about 1 millimeter of HO. More preferably, the mouthpiece filter segment has an RTD of at least less than about 2 millimeters of HO. Even more preferably, the mouthpiece filter segment has an RTD of at least less than about 5 millimeters of HO.

[0055] RTD values ​​of about 1 millimeter HO to about 10 millimeters HO are particularly preferred because a mouthpiece filter segment having such an RTD is expected to contribute minimally to the overall RTD of the aerosol-generating article and will not substantially filter the aerosol delivered to the consumer.

[0056] The mouthpiece section preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The mouthpiece section may have an outer diameter of about 5 millimeters to about 10 millimeters, or about 6 millimeters to about 8 millimeters. In a preferred embodiment, the mouthpiece section has an outer diameter of about 7.2 millimeters.

[0057] In some embodiments, the mouthpiece section preferably has a length of from about 1 millimeter to about 10 millimeters, more preferably from about 3 millimeters to about 9 millimeters, and even more preferably from about 5 millimeters to about 9 millimeters.

[0058] For example, the mouthpiece section may have a length of about 1 millimeter to about 10 millimeters, or about 3 millimeters to about 9 millimeters, or about 5 millimeters to about 9 millimeters. In a preferred embodiment, the mouthpiece section has a length of approximately 7 millimeters.

[0059] In certain preferred embodiments of the present invention, the mouthpiece section has a length of up to 10 millimeters, or less than 10 millimeters. Thus, in such embodiments, the mouthpiece section is relatively short compared to mouthpiece sections provided in prior art articles. Providing a relatively short mouthpiece section in the aerosol-generating article of the present invention can provide several benefits to consumers. A shorter mouthpiece section can result in a lower resistance to draw (RTD) for the mouthpiece section. This can improve aerosol delivery and efficiently deliver aerosol formers, such as nicotine and / or glycerin, while maintaining or reducing HPHC levels. Furthermore, a shorter mouthpiece section reduces the amount of plasticizers used in the manufacture of the mouthpiece element, improving the sustainability of the product.

[0060] In particularly preferred embodiments of the present invention, a mouthpiece section having a length of up to or less than 10 millimeters is combined with a relatively short aerosol-cooling segment, e.g., an aerosol-cooling segment having a length of at least 10 millimeters, which combination provides satisfactory delivery of aerosol, particularly nicotine and glycerin, while maintaining low or even reducing levels of HPHCs.

[0061] According to the present invention, the length of the mouthpiece section is at least about 0.10 times the length of the intermediate hollow section, preferably at least about 0.15 times the length of the intermediate hollow section, more preferably at least about 0.20 times the length of the intermediate hollow section, even more preferably at least about 0.25 times the length of the intermediate hollow section, and most preferably at least about 0.30 times the length of the intermediate hollow section. Thus, the ratio of the length of the mouthpiece section to the length of the intermediate hollow section is at least about 0.10, preferably at least about 0.15, more preferably at least about 0.20, even more preferably at least about 0.25, and most preferably at least about 0.30.

[0062] In accordance with the present invention, the length of the mouthpiece section is less than about 0.40 times the length of the intermediate hollow section, preferably less than about 0.38 times the length of the intermediate hollow section, more preferably less than about 0.36 times the length of the intermediate hollow section, and most preferably less than about 0.34 times the length of the intermediate hollow section. Thus, the ratio of the length of the mouthpiece section to the length of the intermediate hollow section is less than about 0.40, preferably less than about 0.38, more preferably less than about 0.36, and most preferably less than about 0.34.

[0063] The ratio of the length of the mouthpiece section to the length of the intermediate hollow section can be at least about 0.10 and less than about 0.40, preferably at least about 0.10 and less than about 0.38, more preferably at least about 0.10 and less than about 0.36, and even more preferably at least about 0.10 and less than 0.34. The ratio of the length of the mouthpiece section to the length of the intermediate hollow section can be at least about 0.15 and less than 0.40, preferably at least about 0.15 and less than about 0.38, more preferably at least about 0.15 and less than about 0.36, and even more preferably at least about 0.15 and less than about 0.34. The ratio of the length of the mouthpiece section to the length of the intermediate hollow section can be at least about 0.20 and less than about 0.40, preferably at least about 0.20 and less than about 0.38, more preferably at least about 0.20 and less than about 0.36, and even more preferably at least about 0.20 and less than 0.34. The ratio of the length of the mouthpiece section to the length of the intermediate hollow section can be at least about 0.25 and less than about 0.40, preferably at least about 0.25 and less than about 0.38, more preferably at least about 0.25 and less than about 0.36, and even more preferably at least about 0.25 and less than 0.34. The ratio of the length of the mouthpiece section to the length of the intermediate hollow section can be at least about 0.30 and less than about 0.40, preferably at least about 0.30 and less than about 0.38, more preferably at least about 0.30 and less than about 0.36, and even more preferably at least about 0.30 and less than 0.34.

[0064] The ratio of the length of the mouthpiece section to the length of the rod of the aerosol-generating substrate may be from about 0.10 to less than about 0.60.

[0065] The ratio of the length of the mouthpiece section to the length of the rod of the aerosol-generating substrate is preferably at least about 0.10, more preferably at least about 0.20, and even more preferably at least about 0.30. In a preferred embodiment, the ratio of the length of the mouthpiece section to the length of the rod of the aerosol-generating substrate is less than about 0.60.

[0066] In some embodiments, the ratio of the length of the mouthpiece section to the length of the rod of the aerosol-generating substrate is from about 0.10 to less than about 0.60, preferably from about 0.20 to less than about 0.60, and more preferably from about 0.30 to less than about 0.60.

[0067] In a particularly preferred embodiment, the ratio of the length of the mouthpiece section to the length of the rod of the aerosol-generating substrate is about 0.58.

[0068] Preferably, the ratio of the length of the mouthpiece section to the length of the aerosol-generation section is at least about 0.10, more preferably at least about 0.20, and even more preferably at least about 0.30. In a preferred embodiment, the ratio of the length of the mouthpiece section to the length of the aerosol-generation section is less than about 0.60.

[0069] In some embodiments, the ratio of the length of the mouthpiece section to the length of the aerosol-generation section is from about 0.10 to less than about 0.60, preferably from about 0.20 to less than about 0.60, and more preferably from about 0.30 to less than about 0.60.

[0070] In a particularly preferred embodiment, the ratio of the length of the mouthpiece section to the length of the aerosol-generation section is about 0.41.

[0071] The ratio of the length of the mouthpiece section to the overall length of the aerosol-generating article may be from about 0.01 to less than about 0.20.

[0072] Preferably, the ratio of the length of the mouthpiece section to the overall length of the aerosol-generating article is at least about 0.05, more preferably at least about 0.07, and even more preferably at least about 0.10. Preferably, the ratio of the length of the mouthpiece section to the overall length of the aerosol-generating article is less than about 0.20.

[0073] In some embodiments, the ratio of the length of the mouthpiece section to the overall length of the aerosol-generating article is preferably from about 0.05 to less than about 0.20, more preferably from about 0.07 to less than about 0.20, and even more preferably from about 0.10 to less than about 0.20.

[0074] In a particularly preferred embodiment, the ratio of the length of the mouthpiece section to the overall length of the aerosol-generating article is about 0.16.

[0075] In a preferred embodiment, the mouthpiece section consists of a single mouthpiece filter segment. The mouthpiece filter segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The mouthpiece filter segment may have an outer diameter of about 5 millimeters to about 10 millimeters, or about 6 millimeters to about 8 millimeters. In a preferred embodiment, the mouthpiece filter segment has an outer diameter of about 7.2 millimeters.

[0076] In some embodiments, the mouthpiece filter segment preferably has a length of from about 1 millimeter to about 10 millimeters, more preferably from about 3 millimeters to about 9 millimeters, and even more preferably from about 5 millimeters to about 9 millimeters.

[0077] For example, the mouthpiece filter segment may have a length of about 1 millimeter to about 10 millimeters, or about 3 millimeters to about 9 millimeters, or about 5 millimeters to about 9 millimeters. In a preferred embodiment, the mouthpiece filter segment has a length of approximately 7 millimeters.

[0078] In certain preferred embodiments of the present invention, the mouthpiece filter segment has a length of up to 10 millimeters, or less than 10 millimeters. In such embodiments, the mouthpiece filter segment is therefore relatively short compared to mouthpiece filter segments provided in prior art articles. Providing a relatively short mouthpiece filter segment in the aerosol-generating article of the present invention can provide several benefits to consumers. Shortening the mouthpiece filter segment can result in a lower resistance to draw (RTD) of the mouthpiece filter segment. This can improve aerosol delivery and efficiently deliver aerosol formers such as nicotine and / or glycerin while maintaining or reducing HPHC levels. Furthermore, shortening the mouthpiece filter segment reduces the amount of plasticizer used in the manufacture of the mouthpiece filter segment, improving the sustainability of the product.

[0079] In particularly preferred embodiments of the invention, a mouthpiece filter segment having a length of up to or less than 10 millimeters is combined with a relatively short aerosol-cooling segment, e.g., an aerosol-cooling segment having a length of at least 10 millimeters, which combination can provide satisfactory delivery of aerosol, particularly nicotine and glycerin, while maintaining low or even reducing levels of HPHCs.

[0080] The mouthpiece filter segment may have a length that is at least about 0.10 times the length of the intermediate hollow section, preferably at least about 0.15 times the length of the intermediate hollow section, more preferably at least about 0.20 times the length of the intermediate hollow section, more preferably at least about 0.25 times the length of the intermediate hollow section, and more preferably at least about 0.30 times the length of the intermediate hollow section.

[0081] The length of the mouthpiece filter segment may be less than 0.40 times the total length of the intermediate hollow section, preferably less than 0.38 times the length of the intermediate hollow section, more preferably less than 0.36 times the length of the intermediate hollow section, and more preferably less than 0.34 times the length of the intermediate hollow section. Thus, the ratio of the length of the mouthpiece filter segment to the total length of the intermediate hollow section is less than about 0.40, preferably less than about 0.38, more preferably less than about 0.36, and most preferably less than about 0.34.

[0082] The ratio of the length of the mouthpiece filter segment to the length of the intermediate hollow section can be at least about 0.10 and less than about 0.40, preferably at least about 0.10 and less than about 0.38, more preferably at least about 0.10 and less than about 0.36, and even more preferably at least about 0.10 and less than 0.34. The ratio of the length of the mouthpiece filter segment to the length of the intermediate hollow section can be at least about 0.15 and less than 0.40, preferably at least about 0.15 and less than about 0.38, more preferably at least about 0.15 and less than about 0.36, and even more preferably at least about 0.15 and less than about 0.34. The ratio of the length of the mouthpiece filter segment to the length of the intermediate hollow section can be at least about 0.20 and less than about 0.40, preferably at least about 0.20 and less than about 0.38, more preferably at least about 0.20 and less than about 0.36, and even more preferably at least about 0.20 and less than 0.34. The ratio of the length of the mouthpiece filter segment to the length of the intermediate hollow section can be at least about 0.25 and less than about 0.40, preferably at least about 0.25 and less than about 0.38, more preferably at least about 0.25 and less than about 0.36, and even more preferably at least about 0.25 and less than 0.34. The ratio of the length of the mouthpiece filter segment to the length of the intermediate hollow section can be at least about 0.30 and less than about 0.40, preferably at least about 0.30 and less than about 0.38, more preferably at least about 0.30 and less than about 0.36, and even more preferably at least about 0.30 and less than 0.34.

[0083] The ratio of the length of the mouthpiece filter segment to the length of the rod of the aerosol-generating substrate may be from about 0.10 to less than about 0.60.

[0084] Preferably, the ratio of the length of the mouthpiece filter segment to the length of the rod of the aerosol-generating substrate is at least about 0.10, more preferably at least about 0.20, and even more preferably at least about 0.30. In a preferred embodiment, the ratio of the length of the mouthpiece filter segment to the length of the rod of the aerosol-generating substrate is less than about 0.60.

[0085] In some embodiments, the ratio of the length of the mouthpiece filter segment to the length of the rod of the aerosol-generating substrate is from about 0.10 to less than about 0.60, preferably from about 0.20 to less than about 0.60, and more preferably from about 0.30 to less than about 0.60.

[0086] In a particularly preferred embodiment, the ratio of the length of the mouthpiece filter segment to the length of the rod of the aerosol-generating substrate is about 0.58.

[0087] Preferably, the ratio of the length of the mouthpiece filter segment to the length of the aerosol-generation section is at least about 0.10, more preferably at least about 0.20, and even more preferably at least about 0.30. In a preferred embodiment, the ratio of the length of the mouthpiece filter segment to the length of the aerosol-generation section is less than about 0.60.

[0088] In some embodiments, the ratio of the length of the mouthpiece filter segment to the length of the aerosol-generation section is from about 0.10 to less than about 0.60, preferably from about 0.20 to less than about 0.60, and more preferably from about 0.30 to less than about 0.60.

[0089] In a particularly preferred embodiment, the ratio of the length of the mouthpiece filter segment to the length of the aerosol-generation section is about 0.41.

[0090] The ratio of the length of the mouthpiece filter segment to the overall length of the aerosol-generating article may be from about 0.01 to less than about 0.20.

[0091] Preferably, the ratio of the length of the mouthpiece filter segment to the overall length of the aerosol-generating article is at least about 0.05, more preferably at least about 0.07, and even more preferably at least about 0.10. Preferably, the ratio of the length of the mouthpiece filter segment to the overall length of the aerosol-generating article is less than about 0.20.

[0092] In some embodiments, the ratio of the length of the mouthpiece filter segment to the overall length of the aerosol-generating article is preferably from about 0.05 to less than about 0.20, more preferably from about 0.07 to less than about 0.20, and even more preferably from about 0.10 to less than about 0.20.

[0093] In a particularly preferred embodiment, the ratio of the length of the mouthpiece filter segment to the overall length of the aerosol-generating article is about 0.16.

[0094] As mentioned above, the downstream section of an aerosol-generating article according to the present invention further comprises an intermediate hollow section comprising an aerosol-cooling segment aligned with and positioned downstream of the aerosol-generation section.

[0095] The aerosol-cooling segment is disposed substantially aligned with the rod of the aerosol-generating substrate. This means that the length dimension of the aerosol-cooling segment is disposed approximately parallel to the longitudinal axis of the rod and article, for example, within ±10 degrees of parallel to the longitudinal axis of the rod. In a preferred embodiment, the aerosol-cooling segment extends along the longitudinal axis of the rod.

[0096] In an aerosol-generating article according to the invention, the aerosol-cooling segment is in the form of a hollow tubular segment defining a cavity extending entirely from the upstream end of the aerosol-cooling segment to the downstream end of the aerosol-cooling segment. Preferably, a ventilation zone is provided at a location along the hollow tubular segment.

[0097] The inventors have found that satisfactory cooling of the aerosol stream generated upon heating of the aerosol-generating substrate and drawn through one such aerosol-cooling segment can be achieved by providing a ventilation zone at a location along the hollow tubular segment. Furthermore, the inventors have found that by disposing the ventilation zone at a precisely defined location along the length of the aerosol-cooling segment, and preferably by utilizing a hollow tubular segment having a predetermined peripheral wall thickness or internal volume, as described in more detail below, it may be possible to counter the effects of increased aerosol dilution caused by ventilation air entering the article.

[0098] Without being bound by theory, it is believed that the introduction of ventilated air rapidly reduces the temperature of the aerosol stream as it moves toward the mouthpiece section, so that the ventilated air enters the aerosol stream relatively close to the upstream end of the aerosol-cooling segment (i.e., close enough to the susceptor element extending into the rod-shaped aerosol-generating substrate, which is the heat source in use), achieving dramatic cooling of the aerosol stream, which has a favorable effect on the condensation and nucleation of the aerosol particles. As a result, the overall ratio of aerosol particle phase to aerosol vapor phase may be increased compared to existing non-vented aerosol-generating articles.

[0099] At the same time, maintaining a relatively low peripheral wall thickness of the hollow tubular segment ensures that the overall internal volume of the hollow tubular segment, which becomes available for the aerosol to initiate the nucleation process as soon as the aerosol components leave the aerosol-generating substrate rod, and the cross-sectional area of ​​the hollow tubular segment are effectively maximized, while simultaneously ensuring that the hollow tubular segment has the structural strength necessary to prevent collapse of the aerosol-generating article and provide some support to the aerosol-generating substrate rod, and that the RTD of the hollow tubular segment is minimized. It is understood that a larger value for the cross-sectional area of ​​the cavity of the hollow tubular segment is associated with a reduced velocity of the aerosol stream traveling along the aerosol-generating article, which is expected to promote nucleation. Furthermore, it is understood that utilizing a hollow tubular segment with a relatively low thickness can substantially prevent the diffusion of the ventilation air before it contacts and mixes with the aerosol stream, further favoring the nucleation phenomenon. In effect, 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.

[0100] The aerosol-cooling segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generation section, the rod of aerosol-generating substrate, and the aerosol-generating article.

[0101] The aerosol cooling segment may have an outer diameter of 5 millimeters to 12 millimeters, such as an outer diameter of 5 millimeters to 10 millimeters, or an outer diameter of 6 millimeters to 8 millimeters. In a preferred embodiment, the aerosol cooling segment has an outer diameter of 7.2 millimeters plus or minus 10 percent.

[0102] Preferably, the hollow tubular segment of the aerosol cooling segment has an inner diameter of at least about 2 millimeters. More preferably, the hollow tubular segment of the aerosol cooling segment has an inner diameter of at least about 2.5 millimeters. Even more preferably, the hollow tubular segment of the aerosol cooling segment has an inner diameter of at least about 3 millimeters.

[0103] The peripheral wall of the aerosol-cooling segment may have a thickness of less than about 2.5 millimeters, preferably less than about 1.5 millimeters, more preferably less than about 1250 micrometers, and even more preferably less than about 1000 micrometers. In particularly preferred embodiments, the peripheral wall of the aerosol-cooling segment has a thickness of less than about 900 micrometers, preferably less than about 800 micrometers.

[0104] In one embodiment, the peripheral wall of the aerosol cooling segment has a thickness of about 2 millimeters.

[0105] The aerosol cooling segment may have a length between 5 millimeters and 25 millimeters.

[0106] The aerosol cooling segment preferably has a length of at least about 8 millimeters, and more preferably has a length of at least about 10 millimeters.

[0107] In preferred embodiments, the aerosol-cooling segment has a length of less than about 20 millimeters, more preferably less than about 15 millimeters.

[0108] In some embodiments, the aerosol cooling segment has a length of about 5 millimeters to about 25 millimeters, preferably about 8 millimeters to about 25 millimeters, and more preferably about 10 millimeters to about 25 millimeters. In other embodiments, the aerosol cooling segment has a length of about 5 millimeters to about 20 millimeters, preferably about 8 millimeters to about 20 millimeters, and more preferably about 10 millimeters to about 20 millimeters. In further embodiments, the aerosol cooling segment has a length of about 5 millimeters to about 15 millimeters, preferably about 8 millimeters to about 10 millimeters, and more preferably about 10 millimeters to about 15 millimeters.

[0109] In particularly preferred embodiments of the present invention, the aerosol-cooling segment has a length of at least 10 millimeters. For example, in one particularly preferred embodiment, the aerosol-cooling segment has a length of 13 millimeters. In such an embodiment, the aerosol-cooling segment therefore has a relatively long length compared to aerosol-cooling segments of prior art aerosol-generating articles.

[0110] The ratio of the length of the aerosol-cooling segment to the length of the rod of the aerosol-generating substrate may be from about 0.70 to about 1.50.

[0111] Preferably, the ratio of the length of the aerosol-cooling segment to the length of the rod of the aerosol-generating substrate is at least about 0.80, more preferably at least about 0.90, and even more preferably at least about 1.00.In preferred embodiments, the ratio of the length of the aerosol-cooling segment to the length of the rod of the aerosol-generating substrate is less than about 1.40, more preferably less than about 1.30, and even more preferably less than about 1.20.

[0112] In some embodiments, the ratio of the length of the aerosol-cooling segment to the length of the rod of the aerosol-generating substrate is about 0.80 to about 1.40, preferably about 0.90 to about 1.40, and more preferably about 1.00 to about 1.40. In other embodiments, the ratio of the length of the aerosol-cooling segment to the length of the rod of the aerosol-generating substrate is about 0.80 to about 1.30, preferably about 0.90 to about 1.30, and more preferably about 1.00 to about 1.30. In a further embodiment, the ratio of the length of the aerosol-cooling segment to the length of the rod of the aerosol-generating substrate is about 0.80 to about 1.20, preferably about 0.90 to about 1.20, and more preferably about 1.00 to about 1.20.

[0113] In a particularly preferred embodiment, the ratio of the length of the aerosol-cooling segment to the length of the rod of the aerosol-generating substrate is about 1.08.

[0114] The ratio of the length of the aerosol-cooling segment to the length of the aerosol-generation section can be from about 0.40 to about 1.50.

[0115] Preferably, the ratio of the length of the aerosol-cooling segment to the length of the aerosol-generation section is at least about 0.50, more preferably at least about 0.60, and even more preferably at least about 0.70. In preferred embodiments, the ratio of the length of the aerosol-cooling segment to the length of the aerosol-generation section is less than about 1.50, more preferably less than about 1.30, and even more preferably less than about 1.10.

[0116] In some embodiments, the ratio of the length of the aerosol-cooling segment to the length of the aerosol-generation section is about 0.50 to about 1.50, preferably about 0.60 to about 1.50, and more preferably about 0.70 to about 1.50. In other embodiments, the ratio of the length of the aerosol-cooling segment to the length of the aerosol-generation section is about 0.50 to about 1.30, preferably about 0.60 to about 1.30, and more preferably about 0.70 to about 1.30. In further embodiments, the ratio of the length of the aerosol-cooling segment to the length of the aerosol-generation section is about 0.50 to about 1.10, preferably about 0.60 to about 1.10, and more preferably about 0.70 to about 1.10.

[0117] In a particularly preferred embodiment, the ratio of the length of the aerosol-cooling segment to the length of the aerosol-generation section is about 0.77.

[0118] The ratio of the length of the aerosol-cooling segment to the overall length of the aerosol-generating article may be from about 0.225 to about 0.475.

[0119] Preferably, the ratio of the length of the aerosol-cooling segment to the overall length of the aerosol-generating article is at least about 0.23, more preferably at least about 0.24, and even more preferably at least about 0.25. Preferably, the ratio of the length of the aerosol-cooling segment to the overall length of the aerosol-generating article is less than about 0.40, more preferably less than about 0.35, and even more preferably less than about 0.30.

[0120] In some embodiments, the ratio of the length of the aerosol-cooling segment to the total length of the aerosol-generating article is preferably about 0.23 to about 0.40, more preferably about 0.24 to about 0.40, and even more preferably about 0.25 to about 0.40. In other embodiments, the ratio of the length of the aerosol-cooling segment to the total length of the aerosol-generating article is preferably about 0.23 to about 0.35, more preferably about 0.24 to about 0.35, and even more preferably about 0.25 to about 0.35. In further embodiments, the ratio of the length of the aerosol-cooling segment to the total length of the aerosol-generating article is preferably about 0.23 to about 0.30, more preferably about 0.24 to about 0.30, and even more preferably about 0.25 to about 0.30.

[0121] In a particularly preferred embodiment, the ratio of the length of the aerosol-cooling segment to the overall length of the aerosol-generating article is about 0.29.

[0122] The length of the mouthpiece filter segment is preferably at least 1 millimeter less than the length of the aerosol-cooling segment, more preferably at least 3 millimeters less than the length of the aerosol-cooling segment, and more preferably at least 5 millimeters less than the length of the aerosol-cooling segment. As discussed above, reducing the length of the aerosol-cooling segment can advantageously allow for increased delivery of nicotine and glycerin to the consumer. The potential technical benefits of providing a relatively short mouthpiece filter segment are discussed above.

[0123] The length of the mouthpiece section is preferably at least 1 millimeter less than the length of the aerosol-cooling segment, more preferably at least 3 millimeters less than the length of the aerosol-cooling segment, and more preferably at least 5 millimeters less than the length of the aerosol-cooling segment. As discussed above, reducing the length of the aerosol-cooling segment can advantageously allow for increased delivery of nicotine and glycerin to the consumer. The potential technical benefits of providing a relatively short mouthpiece filter section are discussed above.

[0124] Preferably, in an aerosol-generating article according to the present invention, the aerosol-cooling segment has an average radial hardness of at least about 80 percent, more preferably at least about 85 percent, and even more preferably at least about 90 percent, such that the aerosol-cooling segment can provide the aerosol-generating article with the desired level of hardness.

[0125] If desired, the radial hardness of the aerosol-cooling segment of an aerosol-generating article according to the present invention may be further increased by surrounding the aerosol-cooling segment with a stiff plug wrap, such as a plug wrap having a basis weight of at least about 80 grams per square meter (gsm), or at least about 100 gsm, or at least about 110 gsm.

[0126] As used herein, the term "radial hardness" refers to resistance to compression in a direction transverse to the longitudinal axis of the segment. The radial hardness of an aerosol-generating article around a given element can be determined by applying a load across the article at the location of the segment in a direction transverse to the longitudinal axis of the article and measuring the average (mean) depressed diameter of the article. Radial hardness is given by: [Formula 1] JPEG2026503532000002.jpg1560 formula D S is the original (undepressed) diameter, and D d is the depressed diameter after applying a set load for a set duration. The harder the material, the closer the hardness will be to 100 percent.

[0127] To determine the hardness of a portion of an aerosol article (such as a support segment or an aerosol-cooling segment provided in the form of a hollow tube segment), the aerosol-generating articles should be aligned parallel in a plane, and the same portion of each aerosol-generating article being tested should be subjected to a set load for a set duration. This test is carried out using a known DD60A Densimeter instrument (manufactured and sold by Heinr Borgwaldt GmbH, Germany), which is fitted with a measuring head for an aerosol-generating article such as a cigarette, and which also includes an aerosol-generating article container.

[0128] Load is applied using two load-application cylindrical rods that extend across the diameter of all aerosol-generating articles at once. According to the standard test method for this instrument, the test should be conducted so that twenty points of contact occur between the aerosol-generating articles and the load-application cylindrical rods. In some cases, the hollow tube segment being tested may be long enough so that only ten aerosol-generating articles are needed to form twenty points of contact where each smoking article contacts both load-application rods (because they are long enough to extend between both rods). In other cases, if the support segment is too short to achieve this, twenty aerosol-generating articles should be used to form twenty points of contact, with each aerosol-generating article contacting only one of the load-application rods, as discussed further below.

[0129] Two additional fixed cylindrical rods are positioned below the aerosol-generating article to support the aerosol-generating article and counter the loads exerted by each of the load-applying cylindrical rods.

[0130] For standard operating procedures for such devices, a total load of 2 kg is applied for 20 seconds. After 20 seconds have elapsed (and the load is still applied to the smoking article), the depression on the load-applying cylindrical rod is determined and then used to calculate hardness from the above equation. The temperature is maintained within a range of 22 degrees Celsius ± 2 degrees Celsius. The above test is referred to as the DD60A test. The standard method for measuring filter hardness is when the aerosol-generating article has not yet been consumed. Additional information regarding measuring average radial hardness can be found, for example, in U.S. Published Patent Application Publication No. 2016 / 0128378.

[0131] The aerosol cooling segment may be formed from any suitable material or combination of materials. For example, the aerosol cooling segment may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). Other suitable materials include polyhydroxyalkanoate (PHA) fibers.

[0132] In a preferred embodiment, the aerosol cooling segment is formed from cellulose acetate.

[0133] Preferably, the hollow tubular segment of the aerosol cooling segment is adapted to generate an RTD of approximately 0 millimeters of HO (about 0 Pa) to approximately 20 millimeters of HO (about 100 Pa), more preferably approximately 0 millimeters of HO (about 0 Pa) to approximately 10 millimeters of HO (about 100 Pa).

[0134] In an aerosol-generating article according to the present invention, the overall RTD of the article depends essentially on the RTD of the rod of the aerosol-generating substrate and, optionally, the RTD of the mouthpiece and / or upstream plug, since the hollow tubular segments of the aerosol-cooling element and the hollow tubular segments of the support element are substantially empty and therefore make only a substantially small contribution to the overall RTD of the aerosol-generating article.

[0135] The ventilation zone comprises a plurality of perforations through the peripheral wall of the aerosol-cooling segment. 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 online during manufacture of the aerosol-generating article. Preferably, each peripheral row of perforations comprises between 8 and 30 perforations.

[0136] Aerosol-generating articles according to the present invention may have a breathability level of at least about 5 percent.

[0137] The term "ventilation level" is used throughout this specification to mean the volume ratio of the airflow entering the aerosol-generating article via the ventilation zone (ventilation airflow) to the sum of the aerosol airflow and the ventilation airflow. The greater the ventilation level, the greater the dilution of the aerosol stream delivered to the consumer.

[0138] Aerosol-generating articles may typically have a breathability level of at least about 10 percent, preferably at least about 15 percent, and more preferably at least about 20 percent.

[0139] In a preferred embodiment, the aerosol-generating article has a breathability level of at least about 25 percent. Preferably, the aerosol-generating article has a breathability level of less than about 60 percent. Preferably, the aerosol-generating article according to the present invention has a breathability level of about 45 percent or less. More preferably, the aerosol-generating article according to the present invention has a breathability level of about 40 percent or less, and even more preferably about 35 percent or less.

[0140] In particularly preferred embodiments, the aerosol-generating article has a ventilation level of about 30 percent. In some embodiments, the aerosol-generating article has a ventilation level of about 20 percent to about 60 percent, preferably about 20 percent to about 45 percent, and more preferably about 20 percent to about 40 percent. In other embodiments, the aerosol-generating article has a ventilation level of about 25 percent to about 60 percent, preferably about 25 percent to about 45 percent, and more preferably about 25 percent to about 40 percent. In further embodiments, the aerosol-generating article has a ventilation level of about 30 percent to about 60 percent, preferably about 30 percent to about 45 percent, and more preferably about 30 percent to about 40 percent.

[0141] In particularly preferred embodiments, the aerosol-generating article has a breathability level of about 28 percent to about 42 percent. In some particularly preferred embodiments, the aerosol-generating article has a breathability level of about 30 percent.

[0142] Without wishing to be bound by theory, the inventors have found that the temperature reduction caused by admitting cooler outside air into the hollow tubular segment through the ventilation zone can have a beneficial effect on the nucleation and growth of aerosol particles.

[0143] The formation of aerosols from gaseous mixtures containing various chemical species depends on a delicate interplay between nucleation, evaporation, condensation, and even fusion, which accounts for changes in vapor concentration, temperature, and velocity fields. The so-called classical nucleation theory is based on the assumption that a fraction of molecules in the gas phase are large enough to remain coherent for a long time with a sufficient probability (e.g., a 50 / 50 chance). These molecules represent a certain kind of critical, threshold molecular cluster within the transient molecular aggregates, meaning that smaller molecular clusters generally tend to break down into the gas phase rather quickly, while larger clusters generally tend to grow. These critical clusters are identified as primary nucleation cores from which droplets are expected to grow due to the condensation of molecules from the vapor. It is assumed that freshly nucleated, virgin droplets emerge with a certain original diameter and may subsequently grow by several orders of magnitude. This may be facilitated and enhanced by the rapid cooling of the surrounding vapor, which induces condensation. In this regard, it is helpful to remember that evaporation and condensation are two aspects of one and the same mechanism: gas-liquid mass transfer. Evaporation involves the net mass transfer from the droplets to the gas phase, while condensation is the net mass transfer from the gas phase to the droplet phase. Evaporation (or condensation) causes the droplets to shrink (or grow), but the number of droplets remains the same.

[0144] In this scenario (when the scenario is further complicated by fusion phenomena), the temperature and rate of cooling may play an important role in determining how the system responds. In general, because the nucleation process is typically nonlinear, different cooling rates may lead to significantly different temperature behaviors with respect to the formation of the liquid phase (droplets). Without wishing to be bound by theory, it is hypothesized that cooling can cause a rapid increase in the number of condensed droplets, followed by a short-term, strong increase in this growth (nucleation burst). This nucleation burst appears to be more pronounced at lower temperatures. Furthermore, it appears that a faster cooling rate may favor the onset of early nucleation. In contrast, a decrease in the cooling rate appears to have a favorable effect on the final size that the aerosol droplets ultimately reach.

[0145] Thus, the rapid cooling induced by admitting ambient air into the hollow tubular segment through the ventilation zone can be used to favor favorable nucleation and growth of aerosol droplets. At the same time, however, admitting ambient air into the hollow tubular segment has the direct drawback of diluting the aerosol stream delivered to the consumer.

[0146] The inventors have surprisingly found that the favorable effect of enhanced nucleation promoted by the rapid cooling induced by the introduction of ventilation air into the article can significantly counteract the undesirable effects of dilution, and therefore satisfactory aerosol delivery values ​​are consistently achieved by aerosol-generating articles in accordance with the present invention.

[0147] The inventors have also surprisingly found that the dilution effect on the aerosol—which can be assessed particularly by measuring the effect on the delivery of an aerosol former (such as glycerol) contained in the aerosol-generating substrate—is advantageously minimized when the aeration level is within the ranges described above. In particular, aeration levels of 25 percent to 50 percent, and even more preferably 28 to 42 percent, have been found to lead to particularly satisfactory glycerin delivery values. At the same time, the degree of nucleation, and consequently, the delivery of nicotine and aerosol former (e.g., glycerol), are enhanced.

[0148] This is particularly advantageous for "short" aerosol-generating articles, such as a rod of aerosol-generating substrate less than about 40 millimeters in length, preferably less than 25 millimeters, and even more preferably less than 20 millimeters, or a total length of the aerosol-generating article less than about 70 millimeters, preferably less than about 60 millimeters, and even more preferably less than 50 millimeters. As will be appreciated, in such aerosol-generating articles, there is little time and space for aerosol formation and for the particle phase of the aerosol to become available for delivery to the consumer.

[0149] Furthermore, because the vented hollow tubular segment does not substantially contribute to the overall RTD of the aerosol-generating article, the overall RTD of the article can be advantageously fine-tuned in an aerosol-generating article according to the present invention by adjusting the length and density of the rod of the aerosol-generating substrate, or the length and density of the segment of filtering material that optionally forms part of the mouthpiece, or the length and density of the segment of filtering material provided upstream of the aerosol-generating substrate and susceptor element. Therefore, aerosol-generating articles having a predetermined RTD can be consistently and precisely manufactured, thereby providing a satisfactory level of RTD for the consumer, even in the presence of ventilation.

[0150] In some embodiments, the intermediate hollow section may further comprise one or more additional aerosol cooling segments located downstream of the aerosol cooling segment and capable of abutting the aerosol cooling segment to form a continuous hollow section. In preferred embodiments, the additional aerosol cooling segments include or are in the form of hollow tubular segments. In particularly preferred embodiments, the intermediate hollow section comprises a single additional aerosol cooling segment located downstream of the aerosol cooling segment and capable of abutting the aerosol cooling segment.

[0151] In a preferred embodiment, the additional aerosol-cooling segment has an outer diameter approximately equal to the outer diameter of the mouthpiece filter segment and the outer diameter of the aerosol-generating article. The additional aerosol-cooling segment may have an outer diameter of about 5 millimeters to about 10 millimeters, or about 6 millimeters to about 8 millimeters. In a preferred embodiment, the additional aerosol-cooling segment has an outer diameter of approximately 7.2 millimeters.

[0152] Preferably, the hollow tubular segment of the additional aerosol cooling segment has an inner diameter of at least about 2 millimeters. More preferably, the hollow tubular segment of the additional aerosol cooling segment has an inner diameter of at least about 2.5 millimeters. Even more preferably, the hollow tubular segment of the additional aerosol cooling segment has an inner diameter of at least about 3 millimeters.

[0153] The peripheral wall of the additional aerosol-cooling segment may have a thickness of less than about 2.5 millimeters, preferably less than about 1.5 millimeters, more preferably less than about 1250 micrometers, and even more preferably less than about 1000 micrometers. In particularly preferred embodiments, the peripheral wall of the additional aerosol-cooling segment has a thickness of less than about 900 micrometers, preferably less than about 800 micrometers.

[0154] In one embodiment, the peripheral wall of the additional aerosol cooling segment has a thickness of about 2 millimeters.

[0155] The additional aerosol-cooling segment may have a length of from about 5 millimeters to less than about 10 millimeters.

[0156] In a particularly preferred embodiment, the aerosol cooling segment has a length of 8 millimeters and the additional aerosol cooling segment has a length of 5 millimeters.

[0157] As mentioned above, the intermediate hollow section of the aerosol-generating article according to the present invention further comprises a support segment aligned with and positioned downstream of the aerosol-generation section. In particular, the support segment can be located immediately downstream of the rod of the aerosol-generating substrate, or adjacent to the rod of the aerosol-generating substrate.

[0158] The support segment may be formed from any suitable material or combination of materials. For example, the support segment may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). In a preferred embodiment, the support segment is formed from cellulose acetate. Other suitable materials include polyhydroxyalkanoate (PHA) fibers.

[0159] The support segments may comprise hollow tubular segments. In a preferred embodiment, the support elements comprise hollow cellulose acetate tubes.

[0160] The support segments are positioned substantially aligned with the rod, meaning that the length dimension of the support segments is positioned approximately parallel to the longitudinal axis of the rod and article, for example, within ±10 degrees of parallel to the longitudinal axis of the rod. In a preferred embodiment, the support segments extend along the longitudinal axis of the rod.

[0161] The support segment preferably has an outer diameter approximately equal to the outer diameter of the rod of the aerosol-generating substrate and the outer diameter of the aerosol-generating article.

[0162] The support segment may have an outer diameter of 5 millimeters to 12 millimeters, such as an outer diameter of 5 millimeters to 10 millimeters, or an outer diameter of 6 millimeters to 8 millimeters. In a preferred embodiment, the support segment has an outer diameter of 7.2 millimeters ±10 percent.

[0163] The peripheral wall of the support segment may have a thickness of at least 1 millimeter, preferably at least about 1.5 millimeters, and more preferably at least about 2 millimeters.

[0164] The support segment may have a length of from about 5 millimeters to about 15 millimeters.

[0165] Preferably, the support segment has a length of at least about 6 millimeters, and more preferably at least about 7 millimeters.

[0166] In preferred embodiments, the support segment has a length of less than about 12 millimeters, more preferably less than about 10 millimeters.

[0167] In some embodiments, the support segment has a length of about 5 millimeters to about 15 millimeters, preferably about 6 millimeters to about 15 millimeters, and more preferably about 7 millimeters to about 15 millimeters. In other embodiments, the support segment has a length of about 5 millimeters to about 12 millimeters, preferably about 6 millimeters to about 12 millimeters, and more preferably about 7 millimeters to about 12 millimeters. In further embodiments, the support segment has a length of about 5 millimeters to about 10 millimeters, preferably about 6 millimeters to about 10 millimeters, and more preferably about 7 millimeters to about 10 millimeters.

[0168] In a preferred embodiment, the support segment has a length of about 8 millimeters.

[0169] Preferably, the total length of the intermediate hollow section is about 23 millimeters or less, more preferably about 22 millimeters or less, and most preferably about 21 millimeters or less. Preferably, the total length of the intermediate hollow section is greater than about 16 millimeters, more preferably greater than about 18 millimeters. The total length of the intermediate hollow section can be greater than about 16 millimeters and less than about 23 millimeters, preferably greater than about 16 millimeters and less than about 22 millimeters, and most preferably greater than about 16 millimeters and less than about 21 millimeters. The total length of the intermediate hollow section can be greater than about 18 millimeters and less than about 23 millimeters, more preferably greater than about 18 millimeters and less than about 22 millimeters, and most preferably greater than about 18 millimeters and less than about 21 millimeters.

[0170] In a preferred embodiment, the intermediate hollow section has a length of about 21 millimeters.

[0171] The ratio of the length of the support segment to the length of the rod of the aerosol-generating substrate may be from about 0.25 to about 1.00.

[0172] Preferably, the ratio of the length of the support segment to the length of the rod of the aerosol-generating substrate is at least about 0.30, more preferably at least about 0.40, and even more preferably at least about 0.50. In preferred embodiments, the ratio of the length of the support segment to the length of the rod of the aerosol-generating substrate is less than about 0.90, more preferably less than about 0.80, and even more preferably less than about 0.70.

[0173] In some embodiments, the ratio of the length of the support segment to the length of the rod of the aerosol-generating substrate is about 0.30 to about 0.90, preferably about 0.40 to about 0.90, and more preferably about 0.50 to about 0.90. In other embodiments, the ratio of the length of the support segment to the length of the rod of the aerosol-generating substrate is about 0.30 to about 0.80, preferably about 0.40 to about 0.80, and more preferably about 0.50 to about 0.80. In a further embodiment, the ratio of the length of the support segment to the length of the rod of the aerosol-generating substrate is about 0.30 to about 0.70, preferably about 0.40 to about 0.70, and more preferably about 0.50 to about 0.70.

[0174] In a particularly preferred embodiment, the ratio of the length of the support segment to the length of the rod of the aerosol-generating substrate is about 0.66.

[0175] The ratio of the length of the support segment to the length of the aerosol-generation section can be from about 0.25 to about 1.00.

[0176] Preferably, the ratio of the length of the support segment to the length of the aerosol-generation section is at least about 0.30, more preferably at least about 0.40, and even more preferably at least about 0.45. In preferred embodiments, the ratio of the length of the support segment to the length of the aerosol-generating substrate rod is less than about 0.90, more preferably less than about 0.80, and even more preferably less than about 0.70.

[0177] In some embodiments, the ratio of the length of the support segment to the length of the aerosol-generation section is about 0.30 to about 0.90, preferably about 0.40 to about 0.90, and more preferably about 0.45 to about 0.90. In other embodiments, the ratio of the length of the support segment to the length of the aerosol-generation section is about 0.30 to about 0.80, preferably about 0.40 to about 0.80, and more preferably about 0.45 to about 0.80. In further embodiments, the ratio of the length of the support segment to the length of the aerosol-generation section is about 0.30 to about 0.70, preferably about 0.40 to about 0.70, and more preferably about 0.45 to about 0.70.

[0178] In a particularly preferred embodiment, the ratio of the length of the support segment to the length of the aerosol-generation section is about 0.47.

[0179] The ratio of the length of the support segment to the overall length of the aerosol-generating article may be from about 0.125 to about 0.375.

[0180] Preferably, the ratio of the length of the support segment to the overall length of the aerosol-generating article is at least about 0.13, more preferably at least about 0.14, and even more preferably at least about 0.15. The ratio of the length of the support segment to the overall length of the aerosol-generating article is preferably less than about 0.30, more preferably less than about 0.25, and even more preferably less than about 0.20.

[0181] In some embodiments, the ratio of the length of the support segment to the total length of the aerosol-generating article is preferably about 0.13 to about 0.30, more preferably about 0.14 to about 0.30, and even more preferably about 0.15 to about 0.30. In other embodiments, the ratio of the length of the support segment to the total length of the aerosol-generating article is preferably about 0.13 to about 0.25, more preferably about 0.14 to about 0.25, and even more preferably about 0.15 to about 0.25. In further embodiments, the ratio of the length of the support segment to the total length of the aerosol-generating article is preferably about 0.13 to about 0.20, more preferably about 0.14 to about 0.20, and even more preferably about 0.15 to about 0.20.

[0182] In a particularly preferred embodiment, the ratio of the length of the support segment to the overall length of the aerosol-generating article is about 0.18.

[0183] Preferably, in an aerosol-generating article according to the present invention, the support segment has an average radial hardness of at least about 80 percent, more preferably at least about 85 percent, and even more preferably at least about 90 percent, thereby providing the aerosol-generating article with the desired level of hardness.

[0184] If desired, the radial stiffness of the support segment of an aerosol-generating article according to the present invention may be further increased by surrounding the support element with a stiff plug wrap, such as a plug wrap having a basis weight of at least about 80 grams per square meter (gsm), or at least about 100 gsm, or at least about 110 gsm.

[0185] When inserting an aerosol-generating article according to the present invention into an aerosol-generating device to heat the aerosol-generating substrate, the user may need to apply some force to overcome resistance to insertion of the aerosol-generating substrate of the aerosol-generating article. This may result in damage to one or both of the aerosol-generating article and the aerosol-generating device. In addition, application of force during insertion of the aerosol-generating article into the aerosol-generating device may displace the aerosol-generating substrate within the aerosol-generating article. This may result in the heating element of the aerosol-generating device not being properly aligned with the susceptor element provided within the aerosol-generating substrate, which may lead to uneven and inefficient heating of the aerosol-generating substrate of the aerosol-generating article. The support segments are advantageously configured to resist downstream movement of the aerosol-generating substrate during insertion of the article into the aerosol-generating device.

[0186] Preferably, the hollow tubular segment of the support segment is adapted to generate an RTD of from about 0 millimeters HO (about 0 Pa) to about 20 millimeters HO (about 100 Pa), more preferably from about 0 millimeters HO (about 0 Pa) to about 10 millimeters HO (about 100 Pa). Thus, the support segment preferably does not contribute to the overall RTD of the aerosol-generating article.

[0187] In some embodiments, the intermediate hollow section includes both a support segment comprising a first hollow tubular segment and an aerosol cooling segment comprising a second hollow tubular segment. The inner diameter (D STS) is the inner diameter (D FTS ) is preferably greater than

[0188] More specifically, the inner diameter (D STS ) and the inner diameter (D FTS ) is preferably at least about 1.25. More preferably, the ratio between the inner diameter (D STS ) and the inner diameter (D FTS ) is preferably at least about 1.30. Even more preferably, the ratio between the inner diameter (D STS ) and the inner diameter (D FTS ) is preferably at least about 1.40. In particularly preferred embodiments, the ratio between the inner diameter (D STS ) and the inner diameter (D FTS ) is at least about 1.50, more preferably at least about 1.60.

[0189] The inner diameter (D STS ) and the inner diameter (D FTS ) is preferably about 2.50 or less. STS ) and the inner diameter (D FTS ) is preferably about 2.25 or less. Even more preferably, the ratio between the inner diameter (D STS ) and the inner diameter (D FTS ) is preferably about 2.00 or less.

[0190] In some embodiments, the inner diameter (D STS ) and the inner diameter (D FTS ) is about 1.25 to about 2.50. STS) and the inner diameter (D FTS ) is about 1.30 to about 2.50. STS ) and the inner diameter (D FTS ) is about 1.40 to about 2.50. STS ) and the inner diameter (D FTS ) is about 1.50 to about 2.50.

[0191] In other embodiments, the inner diameter (D STS ) and the inner diameter (D FTS ) is about 1.25 to about 2.25. STS ) and the inner diameter (D FTS ) is about 1.30 to about 2.25. STS ) and the inner diameter (D FTS ) is about 1.40 to about 2.25. In a particularly preferred embodiment, the ratio of the inner diameter (D STS ) and the inner diameter (D FTS ) is about 1.50 to about 2.25.

[0192] In a further embodiment, the inner diameter (D STS ) and the inner diameter (D FTS ) is about 1.25 to about 2.00. STS ) and the inner diameter (D FTS ) is about 1.30 to about 2.00. STS ) and the inner diameter (D FTS) is about 1.40 to about 2.00. STS ) and the inner diameter (D FTS ) is about 1.50 to about 2.00.

[0193] In those embodiments in which the article further comprises an elongated susceptor element longitudinally disposed within the aerosol-generating substrate, the inner diameter (D FTS Preferably, the ratio between the inner diameter (D ) of the first hollow tubular segment and the width of the susceptor element is at least about 0.20. More preferably, FTS ) and the width of the susceptor element is at least about 0.30. Even more preferably, the ratio between the inner diameter (D FTS ) and the width of the susceptor element is at least about 0.40.

[0194] Additionally or alternatively, the inner diameter (D STS Preferably, the ratio between the inner diameter (D ) of the second hollow tubular segment and the width of the susceptor element is at least about 0.20. More preferably, STS ) and the width of the susceptor element is at least about 0.50. Even more preferably, the ratio between the inner diameter (D STS ) and the width of the susceptor element is at least about 0.80.

[0195] Preferably, the ratio between the volume of the cavity of the first hollow tubular segment and the volume of the cavity of the second hollow tubular segment is at least about 0.10, and more preferably, the ratio between the volume of the cavity of the first hollow tubular segment and the volume of the cavity of the second hollow tubular segment is at least about 0.20.

[0196] Preferably, the ratio between the volume of the cavity of the first hollow tubular segment and the volume of the cavity of the second hollow tubular segment is about 0.40 or less, and more preferably, the ratio between the volume of the cavity of the first hollow tubular segment and the volume of the cavity of the second hollow tubular segment is about 0.30 or less.

[0197] As defined above, the aerosol-generating article of the present invention comprises an aerosol-generating section comprising a rod of aerosol-generating substrate.

[0198] The aerosol-generating substrate may be any suitable solid aerosol-generating substrate, such as homogenized plant material, a gel composition comprising an alkaloid compound, a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound, an aerosol-generating substrate comprising a solid aerosol-generating film, or an aerosol-generating substrate comprising thermally conductive particles, etc. Preferably, the aerosol-generating substrate is a solid aerosol-generating film.

[0199] In certain preferred embodiments, the aerosol-generating substrate comprises homogenized plant material, preferably homogenized tobacco material.

[0200] 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, a papermaking process, or any other suitable process known in the art.

[0201] The homogenized plant material may be provided in any suitable form. For example, the homogenized plant material may be in the form of one or more sheets. As used herein, the term "sheet" describes a laminar element having a width and length that is substantially greater than its thickness.

[0202] Alternatively, or additionally, the homogenized plant material may be in the form of a plurality of pellets or granules.

[0203] Alternatively, or additionally, the homogenized plant material may be in the form of a plurality of strands, pieces, or fragments. As used herein, the term "strand" describes an elongated element of material having a length substantially greater than its width and thickness. The term "strand" should be considered to encompass pieces, fragments, and any other homogenized plant material having a similar morphology. Strands of homogenized plant material may be formed from a sheet of homogenized plant material, for example, by cutting or shredding, or by other methods, such as extrusion methods.

[0204] In some embodiments, the strands may be formed in situ within the aerosol-generating substrate as a result of splitting or breaking down the sheet of homogenized plant material during the formation of the aerosol-generating substrate, e.g., as a result of crimping. The strands of homogenized plant material within the aerosol-generating substrate may be separated from one another. Alternatively, each strand of homogenized plant material within the aerosol-generating substrate may be at least partially connected to adjacent strands along its length. For example, adjacent strands may be connected by one or more fibers. This may occur, for example, when strands are formed due to splitting a sheet of homogenized plant material during the manufacture of the aerosol-generating substrate, as described above.

[0205] The aerosol-generating substrate is preferably in the form of one or more sheets of homogenized plant material. In various embodiments of the present invention, the one or more sheets of homogenized plant material may be produced by a casting process. In various embodiments of the present invention, the one or more sheets of homogenized plant material may be produced by a papermaking process. The one or more sheets described herein may each individually have a thickness of 100 micrometers to 600 micrometers, preferably 150 micrometers to 300 micrometers, and most preferably 200 micrometers to 250 micrometers. Individual thickness refers to the thickness of an individual sheet, while combined thickness refers to the total thickness of all sheets comprising the aerosol-generating substrate. For example, if the aerosol-generating substrate is formed from two individual sheets, the combined thickness is the thickness of the two individual sheets, or the sum of the measured thicknesses of the two sheets, stacked within the aerosol-generating substrate.

[0206] One or more of the sheets described herein may each individually have a weight of about 100 g / m 2 ~about 300g / m 2 The weight may have a number of grams.

[0207] One or more of the sheets described herein may each individually have a density of about 0.3 g / cm 3 ~Approx. 1.3g / cm 3 and may have a density of about 0.7 g / cm 3 ~Approx. 1.0g / cm 3 It is preferred that the density of the granular material is 0.05 to 0.15.

[0208] In embodiments of the invention in which the aerosol-generating substrate comprises one or more sheets of homogenized plant material, the sheets are preferably in the form of an assembly of one or more sheets. As used herein, the term "assembly of sheets" refers to sheets of an aerosol-generating substrate or article that have been folded, folded or otherwise compressed or constricted substantially transversely to the longitudinal axis of the aerosol-generating substrate or article, or compressed or constricted substantially transversely to the cylindrical axis of a plug or rod.

[0209] One or more sheets of homogenized plant material may be gathered transversely to their longitudinal axes and surrounded by a wrapper to form a continuous rod or plug.

[0210] One or more sheets of homogenized plant material may advantageously be crimped or similarly treated. As used herein, the term "crimped" means a sheet having a plurality of substantially parallel ridges or corrugations. Alternatively or additionally to being crimped, one or more sheets of homogenized plant material may be embossed, debossed, perforated, or otherwise deformed to provide texture to one or both sides of the sheet.

[0211] Preferably, each sheet of homogenized plant material may be crimped to have a plurality of ridges or corrugations substantially parallel to the cylindrical axis of the plug. This process advantageously facilitates assembling the crimped sheets of homogenized plant material to form a plug. Preferably, one or more sheets of homogenized plant material may be assembled. Of course, the crimped sheets of homogenized plant material may alternatively or additionally have a plurality of substantially parallel ridges or corrugations that form acute or obtuse angles with respect to the cylindrical axis of the plug. The sheet may be crimped to an extent that the integrity of the sheet is disrupted at the plurality of parallel ridges or corrugations, causing separation of the material and resulting in the formation of pieces, strands, or strips of homogenized plant material.

[0212] Alternatively, one or more sheets of homogenized plant material may be cut into strands as mentioned above. In such embodiments, the aerosol-generating substrate includes multiple strands of homogenized plant material. The strands can be used to form plugs. Typically, the width of such strands is about 5 millimeters, about 4 millimeters, about 3 millimeters, or about 2 millimeters or less. The length of the strands may be greater than about 5 millimeters, about 5 millimeters to about 15 millimeters, about 8 millimeters to about 12 millimeters, or even about 12 millimeters. Preferably, the strands have substantially the same length as each other. The length of the strands may be determined by the manufacturing process by which the rod is cut into shorter plugs, and the length of the strands corresponds to the length of the plugs. Strands are fragile and may break, especially during transport. In such cases, the length of some of the strands may be shorter than the length of the plugs.

[0213] The strands preferably extend substantially longitudinally along the length of the aerosol-generating substrate, aligned with the longitudinal axis, and are therefore preferably aligned substantially parallel to one another.

[0214] The homogenized plant material may contain up to about 95 weight percent plant particles on a dry weight basis, preferably up to about 90 weight percent plant particles, more preferably up to about 80 weight percent plant particles, more preferably up to about 70 weight percent plant particles, more preferably up to about 60 weight percent plant particles, and even more preferably up to about 50 weight percent plant particles on a dry weight basis.

[0215] For example, the homogenized plant material can contain, on a dry weight basis, from about 2.5 weight percent to about 95 weight percent plant particles, or from about 5 weight percent to about 90 weight percent plant particles, or from about 10 weight percent to about 80 weight percent plant particles, or from about 15 weight percent to about 70 weight percent plant particles, or from about 20 weight percent to about 60 weight percent plant particles, or from about 30 weight percent to about 50 weight percent plant particles.

[0216] In certain embodiments of the present invention, the homogenized plant material is a homogenized tobacco material comprising tobacco particles. The sheets of homogenized tobacco material used in such embodiments of the present invention may have 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.

[0217] The term "tobacco particles" refers to particles of any plant member of the genus Nicotiana. 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 preferred embodiments, the tobacco particles are derived substantially entirely from tobacco lamina. In contrast, isolated nicotine and nicotine salts, although tobacco-derived compounds, are not considered tobacco particles for purposes of the present invention and are not included in the proportion of particulate plant material.

[0218] The tobacco particles may be prepared from one or more tobacco plant varieties. Any type of tobacco may be used in the blend. Examples of tobacco types that may be used include, but are not limited to, sun-cured tobacco, flue-cured tobacco, burley tobacco, Maryland tobacco, Orient tobacco, Virginia tobacco, and other specialty tobaccos.

[0219] Flame-curing is a tobacco curing method used specifically with Virginia tobacco. During the flue-curing process, heated air is circulated through tightly packed tobacco. During the first stage, the tobacco leaves yellow and wither. During the second stage, the leaf lamina dries completely. During the third stage, the leaf stem dries completely.

[0220] Burley tobacco plays an important role in many tobacco blends. It has a unique flavor and aroma and the ability to absorb large amounts of casing.

[0221] Orient is a type of tobacco with small leaves and high aromatic qualities. However, Orient tobacco has a milder flavor than, for example, Burley. Therefore, Orient tobacco is generally used in relatively small proportions in tobacco blends.

[0222] Kasturi, Madura, and Jatim are subtypes of sun-cured tobacco that can be used. Preferably, Kasturi and flue-cured tobaccos are blended to produce tobacco particles. Thus, the tobacco particles in the particulate plant material can comprise a blend of Kasturi and flue-cured tobaccos.

[0223] The tobacco particles may have a nicotine content of at least about 2.5 weight percent on a dry weight basis, more preferably at least about 3 weight percent, even more preferably at least about 3.2 weight percent, even more preferably at least about 3.5 weight percent, and most preferably at least about 4 weight percent on a dry weight basis.

[0224] In certain other embodiments of the present invention, the homogenized plant material comprises tobacco particles in combination with non-tobacco plant flavor particles. Preferably, the non-tobacco plant flavor particles are selected from one or more of ginger, rosemary, eucalyptus, clove, and star anise particles. Preferably, in these embodiments, the homogenized plant material comprises, on a dry weight basis, at least about 2.5 weight percent of non-tobacco plant flavor particles, with the remaining plant particles being tobacco particles. Preferably, the homogenized plant material comprises, on a dry weight basis, at least about 4 weight percent of non-tobacco plant flavor particles, more preferably at least about 6 weight percent of non-tobacco plant flavor particles, more preferably at least about 8 weight percent of non-tobacco plant flavor particles, and more preferably at least about 10 weight percent of non-tobacco plant flavor particles. Preferably, the homogenized plant material comprises, on a dry weight basis, at most about 20 weight percent of non-tobacco plant flavor particles, more preferably at most about 18 weight percent of non-tobacco plant flavor particles, and more preferably at most about 16 weight percent of non-tobacco plant flavor particles.

[0225] The weight ratio of non-tobacco plant flavor particles to tobacco particles in the particulate plant material forming the homogenized plant material can vary depending on the desired flavor characteristics and composition of the aerosol generated from the aerosol-generating substrate during use. Preferably, the homogenized plant material comprises, on a dry weight basis, at least a 1:30 weight ratio of non-tobacco plant flavor particles to tobacco particles, more preferably at least a 1:20 weight ratio of non-tobacco plant flavor particles to tobacco particles, more preferably at least a 1:10 weight ratio of non-tobacco plant flavor particles to tobacco particles, and most preferably at least a 1:5 weight ratio of non-tobacco plant flavor particles to tobacco particles.

[0226] Alternatively, or in addition to including tobacco particles in the homogenized plant material of the aerosol-generating substrate according to the present invention, the homogenized plant material may include cannabis particles. The term "cannabis particles" refers to particles of cannabis plants, such as Cannabis sativa, Cannabis indica, and Cannabis ruderalis.

[0227] The homogenized plant material preferably comprises no more than 95 weight percent particulate plant material on a dry weight basis. Accordingly, the particulate plant material is typically combined with one or more other ingredients to form the homogenized plant material.

[0228] The homogenized plant material may further comprise a binder for modifying the mechanical properties of the particulate plant material, wherein the binder is included in the homogenized plant material during production as described herein. Suitable exogenous binders known to those skilled in the art are known in the art and include, but are not limited to, gums such as guar gum, xanthan gum, gum arabic, and locust bean gum; cellulose binders such as hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose; polysaccharides such as starch, organic acids such as alginic acid, sodium alginate, agar, and conjugate base salts of organic acids such as pectin, and combinations thereof. Preferably, the binder comprises guar gum.

[0229] The binder may be present in an amount of about 1 weight percent to about 10 weight percent based on the dry weight of the homogenized plant material, preferably in an amount of about 2 weight percent to about 5 weight percent based on the dry weight of the homogenized plant material.

[0230] Alternatively, or additionally, the homogenized plant material may further comprise one or more lipids to enhance the diffusion rate of the volatile components (e.g., aerosol-forming agents, gingerol, and nicotine), where the lipids are included in the homogenized plant material during the processes described herein. Suitable lipids for inclusion in the homogenized plant material include, but are not limited to, medium chain triglycerides, cocoa butter, palm oil, palm kernel oil, mango oil, shea butter, soybean oil, cottonseed oil, coconut oil, hydrogenated coconut oil, candelilla wax, carnauba wax, shellac, sunflower wax, sunflower oil, rice bran, and Revel A, and combinations thereof.

[0231] Alternatively, or additionally, the homogenized plant material may further comprise a pH adjuster.

[0232] Alternatively, or in addition, the homogenized plant material may further comprise fibers to alter the mechanical properties of the homogenized plant material, where the fibers are included in the homogenized plant material during the processes described herein. Suitable exogenous fibers for inclusion in the homogenized plant material are known in the art and include fibers formed from non-tobacco and non-ginger materials, including, but not limited to, cellulose fibers, soft wood fibers, hard wood fibers, jute fibers, and combinations thereof. Exogenous fibers derived from tobacco and / or ginger may also be added. Any fibers added to the homogenized plant material are not considered to form part of the "particulate plant material" defined above. Prior to inclusion in the homogenized plant material, the fibers may be processed by a suitable process known in the art, including, but not limited to, mechanical pulping, refining, chemical pulping, bleaching, sulfate pulping, and combinations thereof. Typically, the fibers have a length greater than their width.

[0233] Suitable fibers are typically greater than 400 micrometers and have a length of 4 millimeters or less, with lengths in the range of 0.7 millimeters to 4 millimeters being preferred. The fibers are preferably present in an amount of about 2 weight percent to about 15 weight percent, most preferably about 4 weight percent, based on the dry weight of the substrate.

[0234] Alternatively, or in addition, the homogenized plant material may further comprise one or more aerosol formers. Upon volatilization, the aerosol formers can carry other vaporized compounds, such as nicotine and flavorants, that are released from the aerosol-generating substrate upon heating. Suitable aerosol formers for inclusion in the homogenized plant material are known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, propylene glycol, 1,3-butanediol, and glycerol), esters of polyhydric alcohols (such as glycerol mono-, di-, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and tetradecanedioate).

[0235] The homogenized plant material may have an aerosol former content of from about 5 weight percent to about 30 weight percent on a dry weight basis, such as from about 10 weight percent to about 25 weight percent on a dry weight basis, or from about 15 weight percent to about 20 weight percent on a dry weight basis.

[0236] For example, when the substrate is intended for use in an aerosol-generating article for an electrically-operated aerosol-generating system having a heating element, the aerosol former content may preferably be about 5 weight percent to about 30 weight percent on a dry weight basis.When the substrate is intended for use in an aerosol-generating article for an electrically-operated aerosol-generating system having a heating element, the aerosol former is preferably glycerol.

[0237] In other embodiments, the homogenized plant material may have an aerosol former content of about 1 percent to about 5 percent by weight on a dry weight basis. For example, if the substrate is intended for use in an aerosol-generating article in which the aerosol former is held in a reservoir separate from the substrate, the substrate may have an aerosol former content greater than 1 percent and less than about 5 percent. In such embodiments, the aerosol-forming agent volatilizes upon heating, and a stream of the aerosol-forming agent contacts the aerosol-generating substrate so as to incorporate flavors from the aerosol-generating substrate into the aerosol.

[0238] In other embodiments, the homogenized plant material may have an aerosol-forming agent content of about 30 weight percent to about 45 weight percent. This relatively high level of aerosol-forming agent is particularly suitable for aerosol-generating substrates intended to be heated at temperatures below 275 degrees Celsius. In such embodiments, the homogenized plant material preferably further comprises, on a dry weight basis, about 2 weight percent to about 10 weight percent of a cellulose ether and about 5 weight percent to about 50 weight percent of additional cellulose. The use of a combination of a cellulose ether and additional cellulose has been found to result in particularly effective aerosol delivery when used in aerosol-generating substrates having an aerosol-forming agent content of 30 weight percent to 45 weight percent.

[0239] Suitable cellulose ethers include, but are not limited to, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, hydroxyl ethyl cellulose, hydroxyl propyl cellulose, ethyl hydroxyl ethyl cellulose and carboxymethyl cellulose (CMC). In a particularly preferred embodiment, the cellulose ether is carboxymethyl cellulose.

[0240] As used herein, the term "additional cellulose" encompasses any cellulose material incorporated into the homogenized plant material that is not derived from the non-tobacco plant particles or tobacco particles provided therein. Thus, the additional cellulose is incorporated into the homogenized plant material as a separate and distinct cellulose source in addition to the non-tobacco plant material or tobacco material, relative to any cellulose inherently provided within the non-tobacco plant particles or tobacco particles. The additional cellulose is typically derived from a plant different from the non-tobacco plant particles or tobacco particles. Preferably, the additional cellulose is in the form of an inert cellulose material that is sensorily inert and therefore does not substantially affect the sensory properties of the aerosol generated from the aerosol-generating substrate. For example, the additional cellulose is preferably a tasteless and odorless material.

[0241] The additional cellulose may include cellulose powder, cellulose fiber, or a combination thereof.

[0242] The aerosol former may act as a wetting agent in the aerosol-generating substrate.

[0243] The wrapper surrounding the rod of homogenized plant material can be a paper wrapper or a non-paper wrapper. Suitable paper wrappers for use in certain embodiments of the present invention are known in the art and include, but are not limited to, cigarette paper and filter plug wrap. Suitable non-paper wrappers for use in certain embodiments of the present invention are known in the art and include, but are not limited to, sheets of homogenized tobacco material. In certain preferred embodiments, the wrapper may be formed from a laminate material comprising multiple layers. Preferably, the wrapper is formed from an aluminum co-laminate sheet. The use of an aluminum-containing co-laminate sheet advantageously prevents combustion of the aerosol-generating substrate if the aerosol-generating substrate is to be ignited rather than heated in the intended manner.

[0244] In other preferred embodiments of the invention, the aerosol-generating substrate comprises a gel composition comprising an alkaloid compound, or a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound. In particularly preferred embodiments, the aerosol-generating substrate comprises a gel composition comprising nicotine.

[0245] Preferably, the gel composition comprises an alkaloid compound, or a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound, an aerosol former, and at least one gelling agent. Preferably, the at least one gelling agent forms a solid medium, the glycerol is dispersed in the solid medium, and the alkaloid or cannabinoid is dispersed in the glycerol. Preferably, the gel composition is in a stable gel phase.

[0246] Advantageously, the stable gel composition comprising nicotine provides a predictable composition shape upon storage or during transition from manufacture to consumer. The stable gel composition comprising nicotine substantially maintains its shape. The stable gel composition comprising nicotine does not substantially release a liquid phase upon storage or during transition from manufacture to consumer. The stable gel composition comprising nicotine may provide a simple consumable design. The consumable may not need to be designed to contain a liquid, and therefore a wider range of materials and container configurations may be contemplated.

[0247] The gel compositions described herein may be combined with an aerosol generating device to provide nicotine aerosol to the lungs at inhalation or airflow rates within those of traditional smoking. The aerosol generating device may continuously heat the gel composition. The consumer may take multiple inhalations or "puffs," with each "puff" delivering a quantity of nicotine aerosol. Upon heating, the gel composition may deliver a high-nicotine / low total particulate matter (TPM) aerosol to the consumer, preferably in a continuous manner.

[0248] The phrase "stable gel phase" or "stable gel" refers to a gel that substantially maintains its shape and mass when exposed to various environmental conditions. A stable gel cannot substantially release or absorb water (sweat) when exposed to standard temperatures and pressures while varying relative humidity from about 10 percent to about 60 percent. For example, a stable gel can substantially maintain its shape and mass when exposed to standard temperatures and pressures while varying relative humidity from about 10 percent to about 60 percent.

[0249] The gel composition may contain an alkaloid compound, or a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound. The gel composition may contain one or more alkaloids. The gel composition may contain one or more cannabinoids. The gel composition may contain a combination of one or more alkaloids and one or more cannabinoids.

[0250] The term "alkaloid compound" refers to any class of naturally occurring organic compounds containing one or more basic nitrogen atoms. Generally, alkaloids contain at least one nitrogen atom in an amine-type structure. This or another nitrogen atom within the molecule of an alkaloid compound can be active as a base in an acid-base reaction. Most alkaloid compounds have one or more of their nitrogen atoms as part of a ring system, such as a heterocycle. In nature, alkaloid compounds are found primarily in plants and are particularly common in certain families of flowering plants. However, some alkaloid compounds are found in animal species and fungi. In this disclosure, the term "alkaloid compound" refers to both naturally occurring and synthetically produced alkaloid compounds.

[0251] The gel composition preferably comprises an alkaloid compound selected from the group consisting of nicotine, anatabine, and combinations thereof.

[0252] Preferably, the gel composition comprises nicotine.

[0253] The term "nicotine" refers to nicotine and nicotine derivatives (eg, free base nicotine, nicotine salts, and the like).

[0254] The term "cannabinoid compounds" refers to any one of a class of naturally occurring compounds found in parts of the cannabis plant, including Cannabis sativa, Cannabis indica, and Cannabis ruderalis. Cannabinoid compounds are particularly concentrated in the female flower heads. Cannabinoid compounds that occur naturally in cannabis plants include cannabidiol (CBD) and tetrahydrocannabinol (THC). In this disclosure, the term "cannabinoid compounds" is used to describe both naturally occurring and synthetically produced cannabinoid compounds.

[0255] The gel may comprise a cannabinoid compound selected from the group consisting of cannabidiol (CBD), tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), cannabidiolic acid (CBDA), cannabinol (CBN), cannabigerol (CBG), cannabichromene (CBC), cannabicyclol (CBL), cannabivarin (CBV), tetrahydrocannabivarin (THCV), cannabidivarin (CBDV), cannabichromevarin (CBCV), cannabigerovarin (CBGV), cannabigerol monomethyl ether (CBGM), cannabielsoin (CBE), cannabicitran (CBT), and combinations thereof.

[0256] The gel composition may preferably comprise a cannabinoid compound selected from the group consisting of cannabidiol (CBD), THC (tetrahydrocannabinol) and combinations thereof.

[0257] The gel may preferably contain cannabidiol (CBD).

[0258] The gel composition may include nicotine and cannabidiol (CBD).

[0259] The gel composition may include nicotine, cannabidiol (CBD), and THC (tetrahydrocannabinol).

[0260] The gel composition preferably contains about 0.5 to about 10 weight percent alkaloid compounds, or about 0.5 to about 10 weight percent cannabinoid compounds, or a total of about 0.5 to about 10 weight percent alkaloid and cannabinoid compounds. The gel composition may contain about 0.5 to about 5 weight percent alkaloid compounds, or about 0.5 to about 5 weight percent cannabinoid compounds, or a total of about 0.5 to about 5 weight percent alkaloid and cannabinoid compounds. The gel composition preferably contains about 1 to about 3 weight percent alkaloid compounds, or about 1 to about 3 weight percent cannabinoid compounds, or a total of about 1 to about 3 weight percent alkaloid and cannabinoid compounds. The gel composition may preferably contain about 1.5 weight percent to about 2.5 weight percent alkaloid compounds, or about 1.5 weight percent to about 2.5 weight percent cannabinoid compounds, or a total amount of about 1.5 weight percent to about 2.5 weight percent alkaloid compounds and cannabinoid compounds. The gel composition may preferably contain about 2 weight percent alkaloid compounds, or about 2 weight percent cannabinoid compounds, or a total amount of about 2 weight percent alkaloid compounds and cannabinoid compounds. The alkaloid compound component of the gel formulation may be the most volatile component of the gel formulation. In some embodiments, water may be the most volatile component of the gel formulation, and the alkaloid compound component of the gel formulation may be the second most volatile component of the gel formulation. The cannabinoid compound component of the gel formulation may be the most volatile component of the gel formulation. In some embodiments, water may be the most volatile component of the gel formulation, and the alkaloid compound component of the gel formulation may be the second most volatile component of the gel formulation.

[0261] Preferably, nicotine is included in the gel composition. Nicotine can be added to the composition in free base or salt form. The gel composition contains about 0.5 weight percent to about 10 weight percent nicotine, or about 0.5 weight percent to about 5 weight percent nicotine. Preferably, the gel composition contains about 1 weight percent to about 3 weight percent nicotine, or about 1.5 weight percent to about 2.5 weight percent nicotine, or about 2 weight percent nicotine. The nicotine component of the gel formulation can be the most volatile component of the gel formulation. In some embodiments, water can be the most volatile component of the gel formulation, and the nicotine component of the gel formulation can be the second most volatile component of the gel formulation.

[0262] The gel composition preferably includes an aerosol former. Ideally, the aerosol former is substantially resistant to thermal degradation at the operating temperature of the associated aerosol-generating device. Suitable aerosol formers include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate). The polyhydric alcohol or mixture thereof may be one or more of triethylene glycol, 1,3-butanediol, and glycerin (glycerol or propane-1,2,3-triol) or polyethylene glycol. The aerosol former is preferably glycerol.

[0263] The gel composition comprises a majority of the aerosol former. The gel composition may comprise a mixture of water and aerosol former, with the aerosol former forming a majority (by weight) of the gel composition. The aerosol former may form at least about 50 weight percent of the gel composition. The aerosol former may form at least about 60 weight percent, or at least about 65 weight percent, or at least about 70 weight percent of the gel composition. The aerosol former may form about 70 weight percent to about 80 weight percent of the gel composition. The aerosol former may form about 70 weight percent to about 75 weight percent of the gel composition.

[0264] The gel composition may comprise a majority of glycerol. The gel composition may comprise a mixture of water and glycerol, with glycerol forming the majority (by weight) of the gel composition. Glycerol may form at least about 50 weight percent of the gel composition. Glycerol may form at least about 60 weight percent, or at least about 65 weight percent, or at least about 70 weight percent of the gel composition. Glycerol may form about 70 weight percent to about 80 weight percent of the gel composition. Glycerol may form about 70 weight percent to about 75 weight percent of the gel composition.

[0265] The gel composition preferably includes at least one gelling agent. The gel composition preferably includes a total amount of gelling agents ranging from about 0.4 weight percent to about 10 weight percent. More preferably, the composition includes gelling agents in a range of about 0.5 weight percent to about 8 weight percent. More preferably, the composition includes gelling agents in a range of about 1 weight percent to about 6 weight percent. More preferably, the composition includes gelling agents in a range of about 2 weight percent to about 4 weight percent. More preferably, the composition includes gelling agents in a range of about 2 weight percent to about 3 weight percent.

[0266] The term "gelling agent" refers to a compound that, when homogeneously added in an amount of about 0.3 weight percent to a 50 weight percent water / 50 weight percent glycerol mixture, forms a solid medium or support matrix leading to a gel. Gelling agents include, but are not limited to, hydrogen-bond cross-linking gelling agents and ionic cross-linking gelling agents.

[0267] The gelling agent may comprise one or more biopolymers, which may be formed from polysaccharides.

[0268] Examples of biopolymers include gellan gum (natural gellan gum, low acyl gellan gum, high acyl gellan gum, and low acyl gellan gum are preferred), xanthan gum, alginate (alginic acid), agar, and guar gum. It may be preferable for the composition to include xanthan gum. The composition may include two biopolymers. The composition may include three biopolymers. The composition may include two biopolymers in substantially equal amounts by weight. The composition may include three biopolymers in substantially equal amounts by weight.

[0269] Preferably, the gel composition contains at least about 0.2 weight percent of the hydrogen-bond cross-linked gelling agent. Alternatively, or additionally, the gel composition preferably contains at least about 0.2 weight percent of the ionic cross-linked gelling agent. Most preferably, the gel composition contains at least about 0.2 weight percent of the hydrogen-bond cross-linked gelling agent and at least about 0.2 weight percent of the ionic cross-linked gelling agent. The gel composition may contain from about 0.5 weight percent to about 3 weight percent of the hydrogen-bond cross-linked gelling agent and from about 0.5 weight percent to about 3 weight percent of the ionic cross-linked gelling agent, or from about 1 weight percent to about 2 weight percent of the hydrogen-bond cross-linked gelling agent and from about 1 weight percent to about 2 weight percent of the ionic cross-linked gelling agent. The hydrogen-bond cross-linked gelling agent and the ionic cross-linked gelling agent may be present in substantially equal amounts in the gel composition.

[0270] The term "hydrogen-bond cross-linking gelator" refers to a gelator that forms non-covalent or physical cross-links via hydrogen bonds. Hydrogen bonds are not covalent bonds to hydrogen atoms, but rather a type of electrostatic dipole-dipole attraction between molecules. They result from the attraction between a hydrogen atom covalently bonded to another extremely electronegative atom, such as an N, O, or F atom, and another extremely electronegative atom.

[0271] The hydrogen-bond cross-linking gelling agent may comprise one or more of galactomannan, gelatin, agarose, or konjac gum, or agar. Preferably, the hydrogen-bond cross-linking gelling agent comprises agar.

[0272] The gel composition preferably contains from about 0.3 weight percent to about 5 weight percent of the hydrogen-bond cross-linking gelling agent. Preferably, the composition contains from about 0.5 weight percent to about 3 weight percent of the hydrogen-bond cross-linking gelling agent. Preferably, the composition contains from about 1 weight percent to about 2 weight percent of the hydrogen-bond cross-linking gelling agent.

[0273] The gel composition may contain galactomannan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the galactomannan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the galactomannan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the galactomannan may be in the range of about 1 weight percent to about 2 weight percent.

[0274] The gel composition may contain gelatin in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the gelatin may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the gelatin may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the gelatin may be in the range of about 1 weight percent to about 2 weight percent.

[0275] The gel composition may contain agarose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the agarose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the agarose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the agarose may be in the range of about 1 weight percent to about 2 weight percent.

[0276] The gel composition may contain konjac gum in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the konjac gum may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the konjac gum may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the konjac gum may be in the range of about 1 weight percent to about 2 weight percent.

[0277] The gel composition may contain agar in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the agar may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the agar may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the agar may be in the range of about 1 weight percent to about 2 weight percent.

[0278] The term "ionically cross-linking gelator" refers to a gelator that forms non-covalent or physical cross-links through ionic bonds. Ionic cross-linking involves the association of polymer chains through non-covalent interactions. A cross-linked network is formed when multivalent molecules with opposite charges are electrostatically attracted to each other, resulting in a cross-linked polymer network.

[0279] The ionic cross-linking gelling agent may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan or alginate. Preferably, the ionic cross-linking gelling agent may include low acyl gellan.

[0280] The gel composition may comprise an ionically cross-linked gelling agent in the range of about 0.3 weight percent to about 5 weight percent. Preferably, the composition comprises an ionically cross-linked gelling agent in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the composition comprises an ionically cross-linked gelling agent in the range of about 1 weight percent to about 2 weight percent.

[0281] The gel composition may contain low acyl gellan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the low acyl gellan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the low acyl gellan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the low acyl gellan may be in the range of about 1 weight percent to about 2 weight percent.

[0282] The gel composition may comprise pectin in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the pectin may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the pectin may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the pectin may be in the range of about 1 weight percent to about 2 weight percent.

[0283] The gel composition may comprise kappa carrageenan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the kappa carrageenan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the kappa carrageenan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the kappa carrageenan may be in the range of about 1 weight percent to about 2 weight percent.

[0284] The gel composition may comprise iota carrageenan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the iota carrageenan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the iota carrageenan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the iota carrageenan may be in the range of about 1 weight percent to about 2 weight percent.

[0285] The gel composition may comprise alginate in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the alginate may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the alginate may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the alginate may be in the range of about 1 weight percent to about 2 weight percent.

[0286] The gel composition may contain a hydrogen-bond cross-linking gelator and an ionic cross-linking gelator in a ratio of about 3:1 to about 1:3. Preferably, the gel composition may contain a hydrogen-bond cross-linking gelator and an ionic cross-linking gelator in a ratio of about 2:1 to about 1:2. Preferably, the gel composition may contain a hydrogen-bond cross-linking gelator and an ionic cross-linking gelator in a ratio of about 1:1.

[0287] The gel composition may further comprise a thickening agent. The thickening agent in combination with the hydrogen-bond cross-linking gelling agent and the ionic cross-linking gelling agent surprisingly appears to support a solid medium and maintain the gel composition even when the gel composition contains high levels of glycerol.

[0288] The term "thickener" refers to a compound that, when uniformly added in an amount of 0.3 weight percent into a 50 weight percent water / 50 weight percent glycerol mixture at 25°C, increases the viscosity without resulting in the formation of a gel, and the mixture remains or becomes fluid. Preferably, the thickener, when uniformly added in an amount of 0.3 weight percent into a 50 weight percent water / 50 weight percent glycerol mixture at 25°C, increases the viscosity of the mixture without resulting in the formation of a gel, and the mixture remains or becomes fluid. -1Preferably, the thickener, when homogeneously added in an amount of 0.3 weight percent to a 50 weight percent water / 50 weight percent glycerol mixture at 25° C., increases the viscosity by 0.1 s at a shear rate of 0.3 weight percent, preferably at least 500 cPs, preferably at least 1000 cPs, without causing the formation of a gel, and the mixture remains fluid. -1 refers to a compound that increases the viscosity of a mixture at a shear rate of at least 2 times, at least 5 times, at least 10 times, or at least 100 times greater than before addition, and that causes the mixture to become or remain fluid.

[0289] The viscosity values ​​recited herein may be measured using a Brookfield RVT viscometer with a disc type RV#2 spindle rotating at 25° C. at a speed of 6 revolutions per minute (rpm).

[0290] The gel composition preferably comprises a thickening agent in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the composition comprises a thickening agent in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the composition comprises a thickening agent in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the composition comprises a thickening agent in the range of about 1 weight percent to about 2 weight percent.

[0291] The thickening agent may comprise one or more of xanthan gum, carboxymethylcellulose, microcrystalline cellulose, methylcellulose, gum arabic, guar gum, lambda carrageenan, or starch. Preferably, the thickening agent may comprise xanthan gum.

[0292] The gel composition may contain xanthan gum in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the xanthan gum may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the xanthan gum may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the xanthan gum may be in the range of about 1 weight percent to about 2 weight percent.

[0293] The gel composition may contain carboxymethylcellulose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the carboxymethylcellulose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the carboxymethylcellulose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the carboxymethylcellulose may be in the range of about 1 weight percent to about 2 weight percent.

[0294] The gel composition may contain microcrystalline cellulose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the microcrystalline cellulose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the microcrystalline cellulose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the microcrystalline cellulose may be in the range of about 1 weight percent to about 2 weight percent.

[0295] The gel composition may contain methylcellulose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the methylcellulose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the methylcellulose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the methylcellulose may be in the range of about 1 weight percent to about 2 weight percent.

[0296] The gel composition may include gum arabic in the range of about 0.2 weight percent to about 5 weight percent. Preferably, gum arabic may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, gum arabic may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, gum arabic may be in the range of about 1 weight percent to about 2 weight percent.

[0297] The gel composition may contain guar gum in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the guar gum may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the guar gum may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the guar gum may be in the range of about 1 weight percent to about 2 weight percent.

[0298] The gel composition may comprise lambda carrageenan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the lambda carrageenan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the lambda carrageenan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the lambda carrageenan may be in the range of about 1 weight percent to about 2 weight percent.

[0299] The gel composition may comprise starch in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the starch may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the starch may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the starch may be in the range of about 1 weight percent to about 2 weight percent.

[0300] The gel composition may further comprise a divalent cation. Preferably, the divalent cation comprises calcium ions, such as calcium lactate in solution. The divalent cation (e.g., calcium ions) may aid in gel formation in compositions that include a gelling agent, such as an ionically crosslinking gelling agent. Ionic effects may aid gel formation. The divalent cation may be present in the gel composition in a range of about 0.1 to about 1 weight percent, or about 0.5 weight percent.

[0301] The gel composition may further comprise an acid. The acid may comprise a carboxylic acid. The carboxylic acid may comprise a ketone group. Preferably, the carboxylic acid may comprise a ketone group having less than about 10 carbon atoms, such as levulinic acid or lactic acid, or less than about 6 carbon atoms, or less than about 4 carbon atoms. Preferably, the carboxylic acid has three carbon atoms (such as lactic acid). Lactic acid surprisingly improves the stability of the gel composition over similar carboxylic acids. The carboxylic acid may aid in gel formation. The carboxylic acid may reduce changes in the alkaloid compound concentration, or cannabinoid compound concentration, or both the alkaloid compound concentration and the cannabinoid compound concentration in the gel composition during storage. The carboxylic acid may reduce changes in the nicotine concentration in the gel composition during storage.

[0302] The gel composition may include a carboxylic acid in the range of about 0.1 weight percent to about 5 weight percent. Preferably, the carboxylic acid may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the carboxylic acid may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the carboxylic acid may be in the range of about 1 weight percent to about 2 weight percent.

[0303] The gel composition may contain lactic acid in the range of about 0.1 weight percent to about 5 weight percent. Preferably, the lactic acid may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the lactic acid may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the lactic acid may be in the range of about 1 weight percent to about 2 weight percent.

[0304] The gel composition may include levulinic acid in the range of about 0.1 weight percent to about 5 weight percent. Preferably, the levulinic acid may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the levulinic acid may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the levulinic acid may be in the range of about 1 weight percent to about 2 weight percent.

[0305] The gel composition preferably contains some water. When the composition contains some water, the gel composition is more stable. The gel composition preferably contains at least about 1 weight percent, or at least about 2 weight percent, or at least about 5 weight percent water. The gel composition preferably contains at least about 10 weight percent or at least about 15 weight percent water.

[0306] The gel composition preferably contains about 8 weight percent to about 32 weight percent water. The gel composition preferably contains about 15 weight percent to about 25 weight percent water. The gel composition preferably contains about 18 weight percent to about 22 weight percent water. The gel composition preferably contains about 20 weight percent water.

[0307] Preferably, the aerosol-generating substrate contains about 150 mg to about 350 mg of the gel composition.

[0308] Preferably, in embodiments including a gel composition, the aerosol-generating substrate includes a porous medium loaded with the gel composition. An advantage of a porous medium loaded with a gel composition is that the gel composition is retained within the porous medium, which may aid in the manufacture, storage, or transportation of the gel composition. This may help maintain the desired shape of the gel composition, particularly during manufacture, transportation, or use.

[0309] The term "porous" is used herein to refer to a material that provides a plurality of pores or openings that allow the passage of air through the material.

[0310] The porous medium may be any suitable porous material capable of holding or retaining the gel composition. Ideally, the porous medium allows the gel composition to move within. In certain embodiments, the porous medium comprises natural, synthetic, or semi-synthetic materials, or a combination thereof. In certain embodiments, the porous medium comprises a sheet material, a foam, or a fiber, e.g., loose fiber, or a combination thereof. In certain embodiments, the porous medium comprises a woven fabric, a nonwoven fabric, or an extruded material, or a combination thereof. Preferably, the porous medium comprises cotton, paper, viscose, PLA, or cellulose acetate, or a combination thereof. Preferably, the porous medium comprises a sheet material, e.g., cotton or cellulose acetate. In a particularly preferred embodiment, the porous medium comprises a sheet made from cotton fibers.

[0311] The porous media used in the present invention may be crimped or chopped. In a preferred embodiment, the porous media is crimped. In an alternative embodiment, the porous media comprises chopped porous media. The crimping or chopping process can be before or after loading the gel composition.

[0312] Crimping the sheet material has the advantage of improving the structure and allowing passageways through the structure. The passageways through the crimped sheet material aid in gel loading, gel retention, and fluid passage through the crimped sheet material. Therefore, there are advantages to using crimped sheet materials as porous media.

[0313] The shredding provides the medium with a high surface area to volume ratio so that it can readily absorb the gel.

[0314] In certain embodiments, the sheet material is a composite material. Preferably, the sheet material is porous. The sheet material may aid in the manufacture of the tubular element containing the gel. The sheet material may aid in the introduction of an active agent into the tubular element containing the gel. The sheet material may help stabilize the structure of the tubular element containing the gel. The sheet material may aid in the transportation or storage of the gel. The use of the sheet material allows or aids in adding structure to the porous medium, for example, by crimping the sheet material.

[0315] The porous medium can be a thread. The thread can include, for example, cotton, paper, or acetate tow. The thread can also be loaded with a gel, like any other porous medium. An advantage of using thread as the porous medium is that it can aid in ease of manufacturing.

[0316] The thread may be loaded with gel by any known means. The thread may simply be coated with gel, or the thread may be impregnated with gel. In manufacturing, the thread may be impregnated with gel and stored ready to be used for inclusion in the assembly of tubular elements.

[0317] The porous medium loaded with the gel composition is preferably provided within a tubular element that forms part of the aerosol-generating article. Ideally, the tubular element has a longitudinal length greater than its width, but this is not necessary, as the tubular element may be part of a multi-component item whose longitudinal length is greater than its width. Typically, the tubular element is cylindrical, but this is not necessary. For example, the tubular element may have an elliptical, polygonal, such as triangular or rectangular, or irregular cross section.

[0318] The tubular element preferably includes a first longitudinal passage. The tubular element is preferably formed from a wrapper that defines the first longitudinal passage. The wrapper is preferably a water-resistant wrapper. This water-resistant property of the wrapper can be achieved by using a water-resistant material or by treating the wrapper material. This can be achieved by treating one or both sides of the wrapper. Being water-resistant can help prevent loss of structure, hardness, or rigidity. This can also help prevent leakage of gel or liquid, especially when using a gel with a fluid structure.

[0319] Embodiments of the present invention in which the aerosol-generating substrate rod comprises the gel composition described above preferably include an upstream segment upstream of the aerosol-generating substrate rod. In this case, the upstream segment advantageously prevents physical contact with the gel composition. The upstream segment can also advantageously compensate for any potential decrease in RTD due to evaporation of the gel composition, for example, when the aerosol-generating substrate rod is heated during use.

[0320] In certain preferred embodiments, the aerosol-generating substrate may comprise or be in the form of a solid aerosol-generating substrate. The solid aerosol-generating substrate may comprise nicotine, one or more cellulosic agents, one or more aerosol formers, and one or more carboxylic acids. The solid aerosol-generating substrate may have a total cellulosic agent content of at least 35 weight percent, a total aerosol former content of at least 45 weight percent, and a total carboxylic acid content of at least 0.5 weight percent. The one or more cellulosic agents may comprise one or more of a cellulosic film-forming agent, a cellulosic reinforcing agent, and a cellulosic binder. The solid aerosol-generating substrate may (i) contain no non-carboxyl alkyl hydroxyl groups and no ketone groups, or (ii) have a pKa in water of 3.5 or less at 25°C, or (iii) contain one or more carboxylic acids that contain no non-carboxyl alkyl hydroxyl groups, no ketone groups, and have a pKa in water of 3.5 or less at 25°C. The one or more carboxylic acids may be selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, undecanoic acid, and C1-C10 saturated alkyl monocarboxylic acids. The solid aerosol-generating substrate may further comprise one or more carboxylic acids selected from lactic acid and levulinic acid.

[0321] The solid aerosol-generating substrate may remain solid when heated to a temperature of between 180° C. and 350° C. As explained further below, this may advantageously reduce or eliminate crusting of the aerosol-generating article.

[0322] For example, the solid aerosol-generating substrate may remain solid when heated to a temperature between 200 degrees Celsius and 320 degrees Celsius, between 220 degrees Celsius and 300 degrees Celsius, or between 240 degrees Celsius and 280 degrees Celsius.

[0323] The solid aerosol-generating substrate may be a solid aerosol-generating film.

[0324] As used herein, the term "film" is used to describe a solid aerosol-generating substrate having a thickness that is substantially less than its width or length.

[0325] As used herein, the term "exposed surface area of ​​the film" refers to the cumulative surface area of ​​the various surfaces of the aerosol-generating film that may be exposed to gaseous airflow through an aerosol-generating article containing the film during use.

[0326] The "weight" of the aerosol-generating film of the aerosol-generating article according to the present invention generally corresponds to the weight of the components of the corresponding film-forming composition minus the weight of the water evaporated during the drying process. If the film is self-supporting, it can be weighed by itself. If the film is placed on a support, the film and the support are weighed, and the weight of the support measured before the film is placed is subtracted from the total weight of the film and the support.

[0327] Unless otherwise stated, the weight percentages of the components of the aerosol-generating film listed herein are based on the total weight of the aerosol-generating film.

[0328] As used herein, the term "thickness" is used to describe the smallest dimension between opposing, substantially parallel surfaces of a solid aerosol-generating film. The thickness of an aerosol-generating film may substantially correspond to the thickness at which the corresponding film-forming composition was cast or extruded, because the cast or extruded film-forming composition does not substantially shrink during drying despite loss of water.

[0329] The solid aerosol-generating film may have a thickness of 0.05 millimeters or more, 0.1 millimeters or more, 0.2 millimeters or more, or 0.3 millimeters or more.

[0330] The solid aerosol-generating film may have a thickness of 1.2 millimeters or less, 1 millimeter or less, 0.8 millimeters or less, 0.6 millimeters or less, or 0.4 millimeters or less.

[0331] The solid aerosol-generating film may have a thickness of 0.05 millimeters to 1.2 millimeters, 0.05 millimeters to 1 millimeter, 0.05 millimeters to 0.8 millimeters, 0.05 millimeters to 0.6 millimeters, or 0.05 millimeters to 0.4 millimeters.

[0332] The solid aerosol-generating film may have a thickness of 0.1 millimeters to 1.2 millimeters, 0.1 millimeters to 1 millimeter, 0.1 millimeters to 0.8 millimeters, 0.1 millimeters to 0.6 millimeters, or 0.1 millimeters to 0.4 millimeters.

[0333] The solid aerosol-generating film may have a thickness of 0.2 millimeters to 1.2 millimeters, 0.2 millimeters to 1 millimeter, 0.2 millimeters to 0.8 millimeters, 0.2 millimeters to 0.6 millimeters, or 0.2 millimeters to 0.4 millimeters.

[0334] The solid aerosol-generating film may have a thickness of 0.3 millimeters to 1.2 millimeters, 0.3 millimeters to 1 millimeter, 0.3 millimeters to 0.8 millimeters, 0.3 millimeters to 0.6 millimeters, or 0.3 millimeters to 0.4 millimeters.

[0335] The solid aerosol-generating film may have a basis weight of 85 grams per square meter or more, 100 grams per square meter or more, 120 grams per square meter or more, or 140 grams per square meter or more.

[0336] The solid aerosol-generating film may have a basis weight of 300 grams per square meter or less, 280 grams per square meter or less, or 260 grams per square meter or less.

[0337] The solid aerosol-generating film may have a basis weight of 85 grams per square meter to 300 grams per square meter, 85 grams per square meter to 280 grams per square meter, or 85 grams per square meter to 260 grams per square meter.

[0338] The solid aerosol-generating film may have a basis weight of from 100 grams per square meter to 300 grams per square meter, from 100 grams per square meter to 280 grams per square meter, or from 100 grams per square meter to 260 grams per square meter.

[0339] The solid aerosol-generating film may have a basis weight of 120 grams per square meter to 300 grams per square meter, 120 grams per square meter to 280 grams per square meter, or 120 grams per square meter to 260 grams per square meter.

[0340] The solid aerosol-generating film may have a basis weight of 140 grams per square meter to 300 grams per square meter, 140 grams per square meter to 280 grams per square meter, or 140 grams per square meter to 260 grams per square meter.

[0341] The solid aerosol-generating film may be formed by any suitable method, for example, the solid aerosol-generating film may be formed by batch casting, continuous casting, or extrusion.

[0342] The solid aerosol-generating film may be self-supporting, that is, the properties of the solid aerosol-generating film may be such that it can be separated from a support surface, even if the solid aerosol-generating film is formed by casting a slurry onto the support surface.

[0343] The solid aerosol-generating film may be disposed on a support, or may be sandwiched between other materials, which may enhance the mechanical stability of the solid aerosol-generating film. For example, the solid aerosol-generating film may be disposed on a layered support.

[0344] In some embodiments, the solid aerosol-generating film may be cut or otherwise divided into a plurality of strips or pieces that can be rolled up to form an aerosol-generating rod for inclusion in an aerosol-generating article.

[0345] In some embodiments, solid aerosol-generating films may be assembled to form an aerosol-generating rod for inclusion in an aerosol-generating article.

[0346] The solid aerosol-generating film may be textured, which may facilitate crimping the solid aerosol-generating film to form, in some embodiments, an aerosol-generating rod for inclusion in an aerosol-generating article.

[0347] The term "textured" is used to describe a solid aerosol-generating film that is crimped, embossed, debossed, perforated, or otherwise modified. A textured solid aerosol-generating film may include a plurality of spaced indentations, protrusions, perforations, or a combination thereof.

[0348] The solid aerosol-generating film may be crimped.

[0349] As used herein, the term "crimped" is intended to be synonymous with the term "crinkled" and is used to describe a solid aerosol-generating film having a plurality of substantially parallel ridges or corrugations.

[0350] The crimped solid aerosol-generating film may have a plurality of ridges or corrugations substantially parallel to the cylindrical axis of the aerosol-generating rod, which may advantageously facilitate assembling the crimped solid aerosol-generating film to form the aerosol-generating rod.

[0351] The solid aerosol-generating film may be textured using suitable known machinery for texturing filter tow, paper and other materials.

[0352] The solid aerosol-generating film may be crimped using a crimping unit of the type described in CH-A-691156, which includes a pair of rotatable crimping rollers, although it will be appreciated that the solid aerosol-generating film may also be textured using other suitable machinery and processes that deform or perforate the solid aerosol-generating film.

[0353] The solid aerosol-generating film may be incorporated directly into an aerosol-generating rod for inclusion in an aerosol-generating article.

[0354] In some embodiments, the solid aerosol-generating film may be applied to a layered substrate before being incorporated into an aerosol-generating rod for inclusion in an aerosol-generating article. For example, the solid aerosol-generating film may be applied to the surface of a sheet material. Sheet materials suitable for use as a layered substrate include, but are not limited to, paper, cardboard, and homogenized plant material. For example, the solid aerosol-generating film may be applied to a paper sheet, an aluminum-coated paper sheet, or a polyethylene-coated paper sheet.

[0355] The layered substrate to which the solid aerosol-generating film is applied can be cut or otherwise divided into a plurality of strips or pieces, as described above.

[0356] The layered substrate to which the solid aerosol-generating film is applied may be assembled as described above.

[0357] The layered substrate to which the solid aerosol-generating film is applied may be textured as described above.

[0358] In some embodiments, the solid aerosol-generating film may be applied to a tubular support prior to incorporation into an aerosol-generating rod for inclusion in an aerosol-generating article. For example, the solid aerosol-generating film may be applied to the inner surface of a hollow tubular support.

[0359] Preferably, the solid aerosol-generating substrate may comprise nicotine.

[0360] As used herein, the term "nicotine" is used to refer to nicotine, nicotine base, or nicotine salt. In some embodiments where the solid aerosol-generating substrate may include nicotine base or nicotine salt, the amounts of nicotine recited herein are the amounts of free base nicotine or the amounts of protonated nicotine, respectively.

[0361] The solid aerosol-generating substrate may comprise natural nicotine, or synthetic nicotine, or a combination of natural and synthetic nicotine.

[0362] The nicotine may comprise one or more nicotine salts selected from the list consisting of nicotine lactate, nicotine citrate, nicotine pyruvate, nicotine bitartrate, nicotine benzoate, nicotine pectinate, nicotine alginate, and nicotine salicylate.

[0363] The nicotine may comprise an extract of tobacco.

[0364] The solid aerosol-generating substrate may have a nicotine content of 0.5 weight percent or more, 1 weight percent or more, 1.5 weight percent or more, or 2 weight percent or more.

[0365] The solid aerosol-generating substrate may have a nicotine content of 10 weight percent or less, 8 weight percent or less, 6 weight percent or less, or 4 weight percent or less.

[0366] The solid aerosol-generating substrate may have a nicotine content of from 0.5 to 10 percent by weight, from 0.5 to 8 percent by weight, from 0.5 to 6 percent by weight, or from 0.5 to 4 percent by weight.

[0367] The solid aerosol-generating substrate may have a nicotine content of from 1 to 10 percent by weight, from 1 to 8 percent by weight, from 1 to 6 percent by weight, or from 1 to 4 percent by weight.

[0368] The solid aerosol-generating substrate may have a nicotine content of from 1.5 to 10 percent by weight, from 1.5 to 8 percent by weight, from 1.5 to 6 percent by weight, or from 1.5 to 4 percent by weight.

[0369] The solid aerosol-generating substrate may have a nicotine content of from 2 to 10 percent by weight, from 2 to 8 percent by weight, from 2 to 6 percent by weight, or from 2 to 4 percent by weight.

[0370] The solid aerosol-generating substrate comprises one or more aerosol formers.

[0371] As used herein, the term "aerosol former" is used to describe a compound that, in use, facilitates the formation of an aerosol and that is preferably substantially resistant to thermal decomposition at the operating temperatures of an aerosol-generating article or an aerosol-generating system that includes a solid aerosol-generating substrate.

[0372] Examples of suitable aerosol formers include polyhydric alcohols (such as 1,3-butanediol, glycerin, 1,3-propanediol, propylene glycol, and triethylene glycol), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate).

[0373] Preferably, the one or more aerosol formers comprise one or more polyhydric alcohols selected from 1,3-butanediol, glycerin, 1,3-propanediol, propylene glycol, and triethylene glycol.

[0374] More preferably, the one or more aerosol formers comprise one or more polyhydric alcohols selected from glycerin and propylene glycol. Even more preferably, the one or more aerosol formers comprise glycerin.

[0375] Most preferably, the one or more aerosol formers may be glycerin.

[0376] The solid aerosol-generating substrate has a total aerosol-former content of 45 weight percent or greater.

[0377] The term "total aerosol former content" is used to describe the combined content of all aerosol formers in a solid aerosol-generating substrate.

[0378] The solid aerosol-generating substrate may have a total aerosol-former content of 46 weight percent or more, 48 weight percent or more, 50 weight percent or more, or 52 weight percent or more.

[0379] The solid aerosol-generating substrate may have a total aerosol-former content of 62 weight percent or less, 60 weight percent or less, 58 weight percent or less, 56 weight percent or less, or 54 weight percent or less.

[0380] The solid aerosol-generating substrate may have a total aerosol-former content of 45 weight percent to 62 weight percent, 45 weight percent to 60 weight percent, 45 weight percent to 58 weight percent, 45 weight percent to 56 weight percent, or 45 weight percent to 54 weight percent.

[0381] The solid aerosol-generating substrate may have a total aerosol-former content of 46 weight percent to 62 weight percent, 46 weight percent to 60 weight percent, 46 weight percent to 58 weight percent, 46 weight percent to 56 weight percent, or 46 weight percent to 54 weight percent.

[0382] The solid aerosol-generating substrate may have a total aerosol-former content of 48 weight percent to 62 weight percent, 48 weight percent to 60 weight percent, 48 weight percent to 58 weight percent, 48 weight percent to 56 weight percent, or 48 weight percent to 54 weight percent.

[0383] The solid aerosol-generating substrate may have a total aerosol-former content of from 50 weight percent to 62 weight percent, from 50 weight percent to 60 weight percent, from 50 weight percent to 58 weight percent, from 50 weight percent to 56 weight percent, or from 50 weight percent to 54 weight percent.

[0384] The solid aerosol-generating substrate may have a total aerosol-former content of from 52 weight percent to 62 weight percent, from 52 weight percent to 60 weight percent, from 52 weight percent to 58 weight percent, from 52 weight percent to 56 weight percent, or from 52 weight percent to 54 weight percent.

[0385] The solid aerosol-generating substrate preferably comprises one or more polyhydric alcohols.

[0386] The solid aerosol-generating substrate may have a total polyhydric alcohol content of 45 weight percent or greater, 46 weight percent or greater, 48 weight percent or greater, 50 weight percent or greater, or 52 weight percent or greater.

[0387] The term "total polyhydric alcohol content" is used to describe the combined content of all polyhydric alcohols in a solid aerosol-generating substrate.

[0388] The solid aerosol-generating substrate may have a total polyhydric alcohol content of 62 weight percent or less, 60 weight percent or less, 58 weight percent or less, 56 weight percent or less, or 54 weight percent or less.

[0389] The solid aerosol-generating substrate may have a total polyhydric alcohol content of 45 weight percent to 62 weight percent, 45 weight percent to 60 weight percent, 45 weight percent to 58 weight percent, 45 weight percent to 56 weight percent, or 45 weight percent to 54 weight percent.

[0390] The solid aerosol-generating substrate may have a total polyhydric alcohol content of 46 weight percent to 62 weight percent, 46 weight percent to 60 weight percent, 46 weight percent to 58 weight percent, 46 weight percent to 56 weight percent, or 46 weight percent to 54 weight percent.

[0391] The solid aerosol-generating substrate may have a total polyhydric alcohol content of 48 weight percent to 62 weight percent, 48 weight percent to 60 weight percent, 48 weight percent to 58 weight percent, 48 weight percent to 56 weight percent, or 48 weight percent to 54 weight percent.

[0392] The solid aerosol-generating substrate may have a total polyhydric alcohol content of from 50 to 62 weight percent, from 50 to 60 weight percent, from 50 to 58 weight percent, from 50 to 56 weight percent, or from 50 to 54 weight percent.

[0393] The solid aerosol-generating substrate may have a total polyhydric alcohol content of 52 weight percent to 62 weight percent, 52 weight percent to 60 weight percent, 52 weight percent to 58 weight percent, 52 weight percent to 56 weight percent, or 52 weight percent to 54 weight percent.

[0394] Preferably, the solid aerosol-generating substrate comprises one or more polyhydric alcohols selected from 1,3-butanediol, glycerin, 1,3-propanediol, propylene glycol, and triethylene glycol.

[0395] More preferably, the solid aerosol-generating substrate comprises one or more polyhydric alcohols selected from glycerin and propylene glycol.

[0396] Most preferably, the solid aerosol-generating substrate comprises glycerin.

[0397] The solid aerosol-generating substrate may have a glycerin content of 35 weight percent or more, 40 weight percent or more, 45 weight percent or more, 46 weight percent or more, 48 weight percent or more, 50 weight percent or more, or 52 weight percent or more.

[0398] The solid aerosol-generating substrate may have a glycerin content of 62 weight percent or less, 60 weight percent or less, 58 weight percent or less, 56 weight percent or less, or 54 weight percent or less.

[0399] The solid aerosol-generating substrate may have a glycerin content of 35 weight percent to 62 weight percent, 35 weight percent to 60 weight percent, 35 weight percent to 58 weight percent, 35 weight percent to 56 weight percent, or 35 weight percent to 54 weight percent.

[0400] The solid aerosol-generating substrate may have a total glycerin content of 40 to 62 weight percent, 40 to 60 weight percent, 40 to 58 weight percent, 40 to 56 weight percent, or 40 to 54 weight percent.

[0401] The solid aerosol-generating substrate may have a glycerin content of 45 to 62 weight percent, 45 to 60 weight percent, 45 to 58 weight percent, 45 to 56 weight percent, or 45 to 54 weight percent.

[0402] The solid aerosol-generating substrate may have a glycerin content of 46 weight percent to 62 weight percent, 46 weight percent to 60 weight percent, 46 weight percent to 58 weight percent, 46 weight percent to 56 weight percent, or 46 weight percent to 54 weight percent.

[0403] The solid aerosol-generating substrate may have a glycerin content of 48 to 62 percent by weight, 48 to 60 percent by weight, 48 to 58 percent by weight, 48 to 56 percent by weight, or 48 to 54 percent by weight.

[0404] The solid aerosol-generating substrate may have a total glycerin content of from 50 to 62 weight percent, from 50 to 60 weight percent, from 50 to 58 weight percent, from 50 to 56 weight percent, or from 50 to 54 weight percent.

[0405] The solid aerosol-generating substrate may have a total glycerin content of 52 weight percent to 62 weight percent, 52 weight percent to 60 weight percent, 52 weight percent to 58 weight percent, 52 weight percent to 56 weight percent, or 52 weight percent to 54 weight percent.

[0406] The solid aerosol-generating substrate comprises one or more carboxylic acids.

[0407] The solid aerosol-generating substrate may comprise a plurality of carboxylic acids, i.e., the solid aerosol-generating substrate may comprise two or more carboxylic acids, for example, the solid aerosol-generating substrate may comprise two carboxylic acids, three carboxylic acids, four carboxylic acids, or five carboxylic acids.

[0408] It has surprisingly been found that by including one or more carboxylic acids in the solid aerosol-generating substrate of an aerosol-generating article, the stability of the solid aerosol-generating substrate during storage of the aerosol-generating article can be advantageously improved. It has surprisingly been found that by including one or more carboxylic acids in the solid aerosol-generating substrate of an aerosol-generating article, the stability of nicotine in the solid aerosol-generating substrate during storage of the aerosol-generating article can be advantageously improved. In particular, it has surprisingly been found that by including one or more carboxylic acids in the solid aerosol-generating substrate of an aerosol-generating article, the corrosion of components of the aerosol-generating article can be advantageously inhibited. In particular, it has surprisingly been found that by including one or more carboxylic acids in the solid aerosol-generating substrate of an aerosol-generating article, the corrosion of metal components of the aerosol-generating article can be advantageously inhibited. In particular, it has surprisingly been found that by including one or more carboxylic acids in the solid aerosol-generating substrate of an aerosol-generating article, the corrosion of a susceptor of the aerosol-generating article can be advantageously inhibited. In some embodiments, the susceptor may be in direct contact with the aerosol-generating substrate.

[0409] Without wishing to be bound by theory, it is believed that when included in a solid aerosol-generating substrate, carboxylic acids that do not contain non-carboxyl alkyl hydroxyl groups are less likely to oxidize other components of the aerosol-generating article than carboxylic acids that contain non-carboxyl alkyl hydroxyl groups. Without wishing to be bound by theory, it is believed that when included in a solid aerosol-generating substrate, carboxylic acids that do not contain ketone groups are less likely to oxidize other components of the aerosol-generating article than carboxylic acids that contain ketone groups. It is believed that including one or more carboxylic acids that do not contain non-carboxyl alkyl hydroxyl groups and do not contain ketone groups in the solid aerosol-generating substrate thereby inhibits corrosion of the components of the aerosol-generating article.

[0410] Without wishing to be bound by theory, it is believed that when included in a solid aerosol-generating substrate, carboxylic acids having a pKa of 3.5 or less are less likely to oxidize other components of the aerosol-generating article than carboxylic acids having a pKa greater than 3.5. It is believed that including one or more carboxylic acids having a pKa of 3.5 or less in the solid aerosol-generating substrate thereby inhibits corrosion of components of the aerosol-generating article.

[0411] The solid aerosol-generating substrate may (i) contain no non-carboxyl alkyl hydroxyl groups and no ketone groups, or (ii) have a pKa in water of 3.5 or less at 25°C, or (iii) contain one or more carboxylic acids that contain no non-carboxyl alkyl hydroxyl groups, no ketone groups, and have a pKa in water of 3.5 or less at 25°C.

[0412] The solid aerosol-generating substrate may comprise a plurality of carboxylic acids that are free of non-carboxyl alkyl hydroxyl groups and free of ketone groups. For example, the solid aerosol-generating substrate may comprise benzoic acid and succinic acid.

[0413] The solid aerosol-generating substrate may comprise one or more carboxylic acids having a pKa in water at 25°C of 3.5 or less.

[0414] As used herein in connection with the present invention, the term "carboxylic acid having a pKa in water of 3.5 or less at 25°C" is used to describe monobasic carboxylic acids having a pKa in water of 3.5 or less at 25°C, and polybasic carboxylic acids having a pKa in water of 3.5 or less at 25°C.

[0415] For example, the solid aerosol-generating substrate may include one or more carboxylic acids selected from citric acid, fumaric acid, maleic acid, malic acid, oxalic acid, and salicylic acid.

[0416] The solid aerosol-generating substrate may comprise a plurality of carboxylic acids having a pKa in water of 3.5 or less at 25° C. For example, the solid aerosol-generating substrate may comprise citric acid and malic acid.

[0417] The solid aerosol-generating substrate may comprise one or more carboxylic acids that contain no non-carboxyl alkyl hydroxyl groups, no ketone groups, and have a pKa in water of 3.5 or less at 25° C. For example, the solid aerosol-generating substrate may comprise one or more carboxylic acids selected from fumaric acid, maleic acid, oxalic acid, and salicylic acid.

[0418] The solid aerosol-generating substrate may comprise a plurality of carboxylic acids that contain no non-carboxyl alkyl hydroxyl groups, no ketone groups, and have a pKa in water of 3.5 or less at 25° C. For example, the solid aerosol-generating substrate may comprise fumaric acid and maleic acid.

[0419] The solid aerosol-generating substrate may comprise one or more carboxylic acids having a pKa in water at 25°C of 3.6 or greater.

[0420] As used herein in connection with the present invention, the term "carboxylic acid having a pKa in water of 3.6 or greater at 25°C" is used to describe monobasic carboxylic acids having a pKa in water of 3.6 or greater at 25°C, and polybasic carboxylic acids having a pKa in water of 3.6 or greater at 25°C.

[0421] The solid aerosol-generating substrate may comprise one or more carboxylic acids that contain no non-carboxyl alkyl hydroxyl groups, no ketone groups, and have a pKa in water of 3.6 or greater at 25° C. For example, the solid aerosol-generating substrate may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, and succinic acid.

[0422] The solid aerosol-generating substrate may comprise a plurality of carboxylic acids that contain no non-carboxyl alkyl hydroxyl groups, no ketone groups, and have a pKa in water of 3.6 or greater at 25° C. For example, the solid aerosol-generating substrate may comprise acetic acid and benzoic acid.

[0423] The solid aerosol-generating substrate may further comprise one or more carboxylic acids containing a non-carboxyl alkyl hydroxyl group and having a pKa in water of 3.6 or greater at 25° C. For example, the solid aerosol-generating substrate may further comprise lactic acid.

[0424] The solid aerosol-generating substrate may further comprise one or more carboxylic acids containing a ketone group and having a pKa in water of 3.6 or greater at 25° C. For example, the solid aerosol-generating substrate may further comprise levulinic acid.

[0425] The solid aerosol-generating substrate may comprise a plurality of carboxylic acids having a pKa in water of 3.6 or greater at 25° C. For example, the solid aerosol-generating substrate may comprise benzoic acid and lactic acid.

[0426] The solid aerosol-generating substrate may comprise one or more carboxylic acids having a pKa in water at 25°C of 3.5 or less, and one or more carboxylic acids having a pKa in water at 25°C of 3.6 or more.

[0427] For example, the solid aerosol-generating substrate may include one or more carboxylic acids selected from fumaric acid, maleic acid, and malic acid, and one or more carboxylic acids selected from acetic acid, benzoic acid, lactic acid, and levulinic acid.

[0428] For example, the solid aerosol-generating substrate may include fumaric acid and one or more carboxylic acids selected from acetic acid, benzoic acid, lactic acid, and levulinic acid.

[0429] The solid aerosol-generating substrate may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, undecanoic acid, and C1-C10 saturated alkyl monocarboxylic acids.

[0430] The solid aerosol-generating substrate may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid.

[0431] The solid aerosol-generating substrate may comprise one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid.

[0432] The solid aerosol-generating substrate may comprise one or more carboxylic acids selected from acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid.

[0433] The solid aerosol-generating substrate may comprise one or more carboxylic acids selected from acetic acid, benzoic acid, citric acid, fumaric acid, and maleic acid.

[0434] The solid aerosol-generating substrate may include one or more carboxylic acids selected from fumaric acid, maleic acid, and malic acid.

[0435] Preferably, the solid aerosol-generating substrate comprises one or more carboxylic acids selected from fumaric acid and maleic acid.

[0436] More preferably, the solid aerosol-generating substrate comprises fumaric acid.

[0437] The solid aerosol-generating substrate may further comprise one or more carboxylic acids selected from lactic acid and levulinic acid. Advantageously, the inclusion of one or more carboxylic acids in the aerosol-generating substrate may result in the production of nicotine salts. Advantageously, the inventors have found that lactic acid and levulinic acid are particularly good carboxylic acids for producing nicotine salts.

[0438] The solid aerosol-generating substrate has a total carboxylic acid content of 0.5 weight percent or greater.

[0439] The term "total carboxylic acid content" is used to describe the combined content of all carboxylic acids in a solid aerosol-generating substrate. For example, if a solid aerosol-generating substrate contains carboxylic acids consisting of benzoic acid and fumaric acid, the term "total carboxylic acid content" describes the combined benzoic acid and fumaric acid content of the solid aerosol-generating substrate.

[0440] The solid aerosol-generating substrate may have a total carboxylic acid content of 1 weight percent or greater, 1.5 weight percent or greater, or 2 weight percent or greater.

[0441] The solid aerosol-generating substrate may have a total carboxylic acid content of 8 weight percent or less, 6 weight percent or less, or 4 weight percent or less.

[0442] The solid aerosol-generating substrate may have a total carboxylic acid content of from 0.5 weight percent to 8 weight percent, from 0.5 weight percent to 6 weight percent, or from 0.5 weight percent to 4 weight percent.

[0443] The solid aerosol-generating substrate may have a total carboxylic acid content of from 1 weight percent to 8 weight percent, from 1 weight percent to 6 weight percent, or from 1 weight percent to 4 weight percent.

[0444] The solid aerosol-generating substrate may have a total carboxylic acid content of from 1.5 weight percent to 8 weight percent, from 1.5 weight percent to 6 weight percent, or from 1.5 weight percent to 4 weight percent.

[0445] The solid aerosol-generating substrate may have a total carboxylic acid content of from 2 weight percent to 8 weight percent, from 2 weight percent to 6 weight percent, or from 2 weight percent to 4 weight percent.

[0446] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be 0.5:1 or greater, 1:1 or greater, 1.5:1 or greater, or 2:1 or greater.

[0447] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be 5:1 or less, 4.5:1 or less, 4:1 or less, or 3.5:1 or less.

[0448] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 0.5:1 to 5:1, from 0.5:1 to 4.5:1, from 0.5:1 to 4:1, or from 0.5:1 to 3.5:1.

[0449] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 1:1 to 5:1, from 1:1 to 4.5:1, from 1:1 to 4:1, or from 1:1 to 3.5:1.

[0450] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 1.5:1 to 5:1, from 1.5:1 to 4.5:1, from 1.5:1 to 4:1, or from 1.5:1 to 3.5:1.

[0451] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 2:1 to 5:1, from 2:1 to 4.5:1, from 2:1 to 4:1, or from 2:1 to 3.5:1.

[0452] The solid aerosol-generating substrate may have a fumaric acid content of 0.5 weight percent or more, 1 weight percent or more, 1.5 weight percent or more, or 2 weight percent or more.

[0453] The solid aerosol-generating substrate may have a fumaric acid content of 8 weight percent or less, 6 weight percent or less, or 4 weight percent or less.

[0454] The solid aerosol-generating substrate may have a fumaric acid content of from 0.5 weight percent to 8 weight percent, from 0.5 weight percent to 6 weight percent, or from 0.5 weight percent to 4 weight percent.

[0455] The solid aerosol-generating substrate may have a fumaric acid content of from 1 weight percent to 8 weight percent, from 1 weight percent to 6 weight percent, or from 1 weight percent to 4 weight percent.

[0456] The solid aerosol-generating substrate may have a fumaric acid content of 1.5 weight percent to 8 weight percent, 1.5 weight percent to 6 weight percent, or 1.5 weight percent to 4 weight percent.

[0457] The solid aerosol-generating substrate may have a fumaric acid content of from 2 weight percent to 8 weight percent, from 2 weight percent to 6 weight percent, or from 2 weight percent to 4 weight percent.

[0458] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 0.5:1 or greater, 1:1 or greater, 1.5:1 or greater, or 2:1 or greater.

[0459] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 4:1 or less, or 3.5:1 or less, 3:1 or less, or 2.5:1 or less.

[0460] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 0.5:1 to 4:1, 0.5:1 to 3.5:1, 0.5:1 to 3:1, or 0.5:1 to 2.5:1.

[0461] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 1:1 to 4:1, 1:1 to 3.5:1, 1:1 to 3:1, or 1:1 to 2.5:1.

[0462] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be from 1.5:1 to 4:1, from 1.5:1 to 3.5:1, from 1.5:1 to 3:1, or from 1.5:1 to 2.5:1.

[0463] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 2:1 to 4:1, 2:1 to 3.5:1, 2:1 to 3:1, or 2:1 to 2.5:1.

[0464] The solid aerosol-generating substrate comprises one or more cellulosic agents.

[0465] The term "cellulosic agent" is used to refer to a cellulosic material. Examples of cellulosic agents include cellulosic film formers, cellulosic reinforcing agents, and cellulosic binders.

[0466] The solid aerosol-generating substrate may comprise a plurality of cellulosic agents. That is, the solid aerosol-generating substrate may comprise two or more cellulosic agents. For example, the solid aerosol-generating substrate may comprise two cellulosic agents, three cellulosic agents, four cellulosic agents, or five cellulosic agents.

[0467] The solid aerosol-generating substrate may have a total cellulosic agent content of 25 weight percent or more, or 30 weight percent or more.

[0468] The term "total cellulosic agent content" is used to describe the combined content of all cellulosic film-forming agents in a solid aerosol-generating substrate. For example, if a solid aerosol-generating substrate contains multiple cellulosic agents consisting of a cellulosic film-forming agent, a cellulosic reinforcing agent, and a cellulosic binder, the term "total cellulosic agent content" describes the combined content of the cellulosic film-forming agent, the cellulosic reinforcing agent, and the cellulosic binder in the solid aerosol-generating substrate.

[0469] Preferably, the solid aerosol-generating substrate has a total cellulosic agent content of 35 weight percent or greater.

[0470] The solid aerosol-generating substrate may have a total cellulosic agent content of 36 weight percent or more, 38 weight percent or more, or 40 weight percent or more.

[0471] The solid aerosol-generating substrate may have a total cellulosic agent content of 52 weight percent or less, 50 weight percent or less, 48 ​​weight percent or less, 46 weight percent or less, or 44 weight percent or less.

[0472] The solid aerosol-generating substrate may have a total cellulosic agent content of 35 weight percent to 52 weight percent, 35 weight percent to 50 weight percent, 35 weight percent to 48 weight percent, 35 weight percent to 46 weight percent, or 35 weight percent to 44 weight percent.

[0473] The solid aerosol-generating substrate may have a total cellulosic agent content of 36 weight percent to 52 weight percent, 36 weight percent to 50 weight percent, 36 weight percent to 48 weight percent, 36 weight percent to 46 weight percent, or 36 weight percent to 44 weight percent.

[0474] The solid aerosol-generating substrate may have a total cellulosic agent content of 38 weight percent to 52 weight percent, 38 weight percent to 50 weight percent, 38 weight percent to 48 weight percent, 38 weight percent to 46 weight percent, or 38 weight percent to 44 weight percent.

[0475] The solid aerosol-generating substrate may have a total cellulosic agent content of 40 weight percent to 52 weight percent, 40 weight percent to 50 weight percent, 40 weight percent to 48 weight percent, 40 weight percent to 46 weight percent, or 40 weight percent to 44 weight percent.

[0476] The solid aerosol-generating substrate may comprise one or more cellulosic film-forming agents.

[0477] The term "cellulosic film former" is used to denote a cellulose polymer that has the ability to form a continuous film by itself or in the presence of an auxiliary thickener.

[0478] Advantageously, the solid aerosol-generating substrate may comprise one or more cellulosic film-forming agents selected from carboxymethyl cellulose (CMC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), hydroxyethyl methyl cellulose (HEMC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), and methyl cellulose (MC).

[0479] More advantageously, the solid aerosol-generating substrate may comprise one or more cellulosic film-forming agents selected from carboxymethylcellulose (CMC), ethylcellulose (EC), methylcellulose (MC), and hydroxypropylmethylcellulose (HPMC).

[0480] Most advantageously, the solid aerosol-generating substrate comprises one or more cellulosic film-forming agents selected from carboxymethylcellulose (CMC) and hydroxypropylmethylcellulose (HPMC).

[0481] Preferably, the solid aerosol-generating substrate comprises carboxymethyl cellulose (CMC) and hydroxypropyl methyl cellulose (HPMC).

[0482] Most preferably, the solid aerosol-generating substrate comprises hydroxypropyl methylcellulose (HPMC).

[0483] One or more cellulosic film-forming agents may act as binders for the solid aerosol-generating substrate.

[0484] The solid aerosol-generating substrate may have 15 weight percent or more, 20 weight percent or more, or 25 weight percent or more of total cellulosic film-forming agents.

[0485] As used herein, the term "total cellulosic film-forming agent content" is used to describe the combined content of all cellulosic film-forming agents in a solid aerosol-generating substrate.

[0486] The solid aerosol-generating substrate may have a total cellulosic film-forming agent content of 40 weight percent or less, 35 weight percent or less, or 30 weight percent or less.

[0487] The solid aerosol-generating substrate may have a total cellulosic film-forming agent content of from 15 weight percent to 40 weight percent, from 15 weight percent to 35 weight percent, or from 15 weight percent to 30 weight percent.

[0488] The solid aerosol-generating substrate may have a total cellulosic film-forming agent content of 20 to 40 weight percent, 20 to 35 weight percent, or 20 to 30 weight percent.

[0489] The solid aerosol-generating substrate may have a total cellulosic film-forming agent content of 25 to 40 weight percent, 25 to 35 weight percent, or 25 to 30 weight percent.

[0490] Inclusion of hydroxypropyl methylcellulose in the solid aerosol-generating substrate may advantageously facilitate the manufacture of the solid aerosol-generating substrate. For example, hydroxypropyl methylcellulose may advantageously reduce the overall viscosity of the slurry of solid aerosol-generating substrate components produced during the manufacture of the solid aerosol-generating substrate. A low-viscosity slurry may be more flowable and easier to mix, transfer, and handle during the manufacturing process.

[0491] Hydroxypropyl methylcellulose can advantageously act as a binder for the solid aerosol-generating substrate.

[0492] The solid aerosol-generating substrate may have a hydroxypropyl methylcellulose content of 14 weight percent or more, 16 weight percent or more, 18 weight percent or more, or 20 weight percent or more.

[0493] The solid aerosol-generating substrate may have a hydroxypropyl methylcellulose content of 40 weight percent or less, 35 weight percent or less, 30 weight percent or less, or 25 weight percent or less.

[0494] The solid aerosol-generating substrate may have a hydroxypropyl methylcellulose content of 14 weight percent to 40 weight percent, 14 weight percent to 35 weight percent, 14 weight percent to 30 weight percent, or 14 weight percent to 25 weight percent.

[0495] The solid aerosol-generating substrate may have a hydroxypropyl methylcellulose content of 16 to 40 weight percent, 16 to 35 weight percent, 16 to 30 weight percent, or 16 to 25 weight percent.

[0496] The solid aerosol-generating substrate may have a hydroxypropyl methylcellulose content of 18 weight percent to 40 weight percent, 18 weight percent to 35 weight percent, 18 weight percent to 30 weight percent, or 18 weight percent to 25 weight percent.

[0497] The solid aerosol-generating substrate may have a hydroxypropyl methylcellulose content of 20 to 40 weight percent, 20 to 35 weight percent, 20 to 30 weight percent, or 20 to 25 weight percent.

[0498] The inclusion of carboxymethyl cellulose in the solid aerosol-generating substrate may advantageously reduce or eliminate crusting in the aerosol-generating article.

[0499] As used herein, the term "crusting" is used to describe the formation of a solid layer on a component of an aerosol-generating article.

[0500] Crusting can occur due to components of the solid aerosol-generating substrate melting and then re-solidifying around components of the aerosol-generating article during use. Crusting can be a particular problem in aerosol-generating articles that contain a susceptor that is in direct contact with the solid aerosol-forming substrate. If a crust forms on the susceptor, the crusted susceptor may become ineffective at heating the solid aerosol-generating substrate. This can disadvantageously lead to one or both of reduced nicotine delivery to the user and reduced aerosol formation from the solid aerosol-generating substrate.

[0501] The solid aerosol-generating substrate may include sodium carboxymethylcellulose.

[0502] The solid aerosol-generating substrate may have a carboxymethylcellulose content of 2 weight percent or more, 3 weight percent or more, 4 weight percent or more, or 5 weight percent or more.

[0503] The solid aerosol-generating substrate may have a carboxymethylcellulose content of 12 weight percent or less, 10 weight percent or less, 8 weight percent or less, or 6 weight percent or less.

[0504] The solid aerosol-generating substrate may have a carboxymethylcellulose content of from 2 to 12 percent by weight, from 2 to 10 percent by weight, from 2 to 8 percent by weight, or from 2 to 6 percent by weight.

[0505] The solid aerosol-generating substrate may have a carboxymethylcellulose content of from 3 weight percent to 12 weight percent, from 3 weight percent to 10 weight percent, from 3 weight percent to 8 weight percent, or from 3 weight percent to 6 weight percent.

[0506] The solid aerosol-generating substrate may have a carboxymethylcellulose content of from 4 weight percent to 12 weight percent, from 4 weight percent to 10 weight percent, from 4 weight percent to 8 weight percent, or from 4 weight percent to 6 weight percent.

[0507] The solid aerosol-generating substrate may have a carboxymethylcellulose content of from 5 to 12 weight percent, from 5 to 10 weight percent, from 5 to 8 weight percent, or from 5 to 6 weight percent.

[0508] The solid aerosol-generating substrate may include one or more cellulosic reinforcing agents.

[0509] Inclusion of one or more cellulosic reinforcing agents in a solid aerosol-generating substrate may advantageously increase the tensile strength of the solid aerosol-generating substrate. In particular, when the solid aerosol-generating substrate is a solid aerosol-generating film, inclusion of one or more cellulosic reinforcing agents in the solid aerosol-generating substrate may advantageously increase the tensile strength of the solid aerosol-generating film. Solid aerosol-generating substrates with high tensile strength may advantageously be less likely to deteriorate or break during manufacture and storage.

[0510] Advantageously, the solid aerosol-generating substrate may comprise one or more cellulosic reinforcing agents selected from cellulose fibers, cellulose powder, and microcrystalline cellulose (MCC).

[0511] The solid aerosol-generating substrate preferably comprises cellulose fibres, which can be particularly effective in increasing the tensile strength of the solid aerosol-generating substrate.

[0512] The solid aerosol-generating substrate may have a total cellulosic reinforcing agent content of 5 weight percent or more, 10 weight percent or more, or 15 weight percent or more.

[0513] The term "total cellulosic reinforcing agent content" is used to describe the combined content of all cellulosic reinforcing agents in the solid aerosol-generating substrate.

[0514] The solid aerosol-generating substrate may have a total cellulosic reinforcing agent content of 30 weight percent or less, 25 weight percent or less, or 20 weight percent or less.

[0515] The solid aerosol-generating substrate may have a total cellulosic reinforcing agent content of from 5 weight percent to 30 weight percent, from 5 weight percent to 25 weight percent, or from 5 weight percent to 20 weight percent.

[0516] The solid aerosol-generating substrate may have a total cellulosic reinforcing agent content of from 10 weight percent to 30 weight percent, from 10 weight percent to 25 weight percent, or from 10 weight percent to 20 weight percent.

[0517] The solid aerosol-generating substrate may have a total cellulosic reinforcing agent content of from 15 weight percent to 30 weight percent, from 15 weight percent to 25 weight percent, or from 15 weight percent to 20 weight percent.

[0518] The solid aerosol-generating substrate may comprise cellulose fibres having a length of 0.2 millimetres or more, 0.5 millimetres or more, 0.7 millimetres or more, or 0.9 millimetres or more.

[0519] The solid aerosol-generating substrate may comprise cellulose fibres having a length of 2 millimetres or less, 1.8 millimetres or less, 1.6 millimetres or less, or 1.4 millimetres or less.

[0520] The solid aerosol-generating substrate may comprise cellulose fibers having a length of 0.2 millimeters to 2.0 millimeters, 0.2 millimeters to 1.8 millimeters, 0.2 millimeters to 1.6 millimeters, or 0.2 millimeters to 1.4 millimeters.

[0521] The solid aerosol-generating substrate may comprise cellulose fibers having a length of 0.5 millimeters to 2.0 millimeters, 0.5 millimeters to 1.8 millimeters, 0.5 millimeters to 1.6 millimeters, or 0.5 millimeters to 1.4 millimeters.

[0522] The solid aerosol-generating substrate may comprise cellulose fibers having a length of 0.5 millimeters to 2.0 millimeters, 0.5 millimeters to 1.8 millimeters, 0.5 millimeters to 1.6 millimeters, or 0.5 millimeters to 1.4 millimeters.

[0523] The solid aerosol-generating substrate may comprise cellulose fibers having a length of 0.7 millimeters to 2.0 millimeters, 0.7 millimeters to 1.8 millimeters, 0.7 millimeters to 1.6 millimeters, or 0.7 millimeters to 1.4 millimeters.

[0524] The solid aerosol-generating substrate may comprise cellulose fibers having a length of 0.9 millimeters to 2.0 millimeters, 0.9 millimeters to 1.8 millimeters, 0.9 millimeters to 1.6 millimeters, or 0.9 millimeters to 1.4 millimeters.

[0525] The solid aerosol-generating substrate may have a cellulose fiber content of 2 weight percent or more, 5 weight percent or more, 10 weight percent or more, or 15 weight percent or more.

[0526] The solid aerosol-generating substrate may have a cellulose fiber content of 30 weight percent or less, 25 weight percent or less, or 20 weight percent or less.

[0527] The solid aerosol-generating substrate may have a cellulose fiber content of from 2 to 30 percent by weight, from 2 to 25 percent by weight, or from 2 to 20 percent by weight.

[0528] The solid aerosol-generating substrate may have a cellulose fiber content of from 5 to 30 percent by weight, from 5 to 25 percent by weight, or from 5 to 20 percent by weight.

[0529] The solid aerosol-generating substrate may have a cellulose fiber content of from 10 to 30 weight percent, from 10 to 25 weight percent, or from 10 to 20 weight percent.

[0530] The solid aerosol-generating substrate may have a cellulose fiber content of 15 to 30 percent by weight, 15 to 25 percent by weight, or 15 to 20 percent by weight.

[0531] The solid aerosol-generating substrate may comprise microcrystalline cellulose having a D50 particle size of 5 micrometers or more, 10 micrometers or more, or 15 micrometers or more.

[0532] As used herein, the term "D50 particle size" describes the median particle size of a particulate material. The D50 particle size is the particle size that divides the distribution in half, with half of the particles being larger than the D50 particle size and half of the particles being smaller than the D50 particle size. The particle size distribution can be determined by laser diffraction. For example, the particle size distribution can be determined by laser diffraction using a Malvern Mastersizer 3000 laser diffraction particle size analyzer according to the manufacturer's instructions.

[0533] The solid aerosol-generating substrate may comprise microcrystalline cellulose having a D50 particle size of 100 micrometers or less, 90 micrometers or less, or 80 micrometers or less.

[0534] The solid aerosol-generating substrate may comprise microcrystalline cellulose having a D50 particle size of 5 micrometers to 100 micrometers, 5 micrometers to 90 micrometers, or 5 micrometers to 80 micrometers.

[0535] The solid aerosol-generating substrate may comprise microcrystalline cellulose having a D50 particle size of 10 micrometers to 100 micrometers, 10 micrometers to 90 micrometers, or 10 micrometers to 80 micrometers.

[0536] The solid aerosol-generating substrate may comprise microcrystalline cellulose having a D50 particle size of 15 micrometers to 100 micrometers, 15 micrometers to 90 micrometers, or 150 micrometers to 80 micrometers.

[0537] The solid aerosol-generating substrate may have a microcrystalline cellulose content of 2 weight percent or more, 5 weight percent or more, 10 weight percent or more, or 15 weight percent or more.

[0538] The solid aerosol-generating substrate may have a microcrystalline cellulose content of 30 weight percent or less, 25 weight percent or less, or 20 weight percent or less.

[0539] The solid aerosol-generating substrate may have a microcrystalline cellulose content of from 2 to 30 percent by weight, from 2 to 25 percent by weight, or from 2 to 20 percent by weight.

[0540] The solid aerosol-generating substrate may have a microcrystalline cellulose content of from 5 to 30 percent by weight, from 5 to 25 percent by weight, or from 5 to 20 percent by weight.

[0541] The solid aerosol-generating substrate may have a microcrystalline cellulose content of from 10 to 30 percent by weight, from 10 to 25 percent by weight, or from 10 to 20 percent by weight.

[0542] The solid aerosol-generating substrate may have a microcrystalline cellulose content of from 15 to 30 percent by weight, from 15 to 25 percent by weight, or from 15 to 20 percent by weight.

[0543] The solid aerosol-generating substrate may comprise a cellulose powder having a D50 particle size of 25 micrometers or more, 30 micrometers or more, or 35 micrometers or more.

[0544] The solid aerosol-generating substrate may comprise a cellulose powder having a D50 particle size of 250 micrometers or less, 225 micrometers or less, or 200 micrometers or less.

[0545] The solid aerosol-generating substrate may comprise a cellulose powder having a D50 particle size of 25 micrometers to 250 micrometers, 25 micrometers to 225 micrometers, or 25 micrometers to 200 micrometers.

[0546] The solid aerosol-generating substrate may comprise a cellulose powder having a D50 particle size of 30 micrometers to 250 micrometers, 30 micrometers to 225 micrometers, or 30 micrometers to 200 micrometers.

[0547] The solid aerosol-generating substrate may comprise a cellulose powder having a D50 particle size of 35 micrometers to 250 micrometers, 35 micrometers to 225 micrometers, or 35 micrometers to 200 micrometers.

[0548] The solid aerosol-generating substrate may have a cellulose powder content of 2 weight percent or more, 5 weight percent or more, 10 weight percent or more, or 15 weight percent or more.

[0549] The solid aerosol-generating substrate may have a cellulose powder content of 30 weight percent or less, 25 weight percent or less, or 20 weight percent or less.

[0550] The solid aerosol-generating substrate may have a cellulose powder content of from 2 to 30 percent by weight, from 2 to 25 percent by weight, or from 2 to 20 percent by weight.

[0551] The solid aerosol-generating substrate may have a cellulose powder content of from 5 to 30 percent by weight, from 5 to 25 percent by weight, or from 5 to 20 percent by weight.

[0552] The solid aerosol-generating substrate may have a cellulose powder content of from 10 to 30 percent by weight, from 10 to 25 percent by weight, or from 10 to 20 percent by weight.

[0553] The solid aerosol-generating substrate may have a cellulose powder content of from 15 to 30 percent by weight, from 15 to 25 percent by weight, or from 15 to 20 percent by weight.

[0554] The solid aerosol-generating substrate may comprise water.

[0555] The solid aerosol-generating substrate may have a water content of 5 weight percent or more, 10 weight percent or more, 15 weight percent or more, or 17 weight percent or more, based on the total weight of the solid aerosol-generating substrate.

[0556] The solid aerosol-generating substrate may have a water content of 35 weight percent or less, 30 weight percent or less, or 25 weight percent or less, based on the total weight of the solid aerosol-generating substrate.

[0557] The solid aerosol-generating substrate may have a water content of from 5 to 35 percent by weight, from 5 to 30 percent by weight, or from 5 to 25 percent by weight, based on the total weight of the solid aerosol-generating substrate.

[0558] The solid aerosol-generating substrate may have a water content of from 10 weight percent to 35 weight percent, from 10 weight percent to 30 weight percent, or from 10 weight percent to 25 weight percent, based on the total weight of the solid aerosol-generating substrate.

[0559] The solid aerosol-generating substrate may have a water content of from 15 to 35 percent by weight, from 15 to 30 percent by weight, or from 15 to 25 percent by weight, based on the total weight of the solid aerosol-generating substrate.

[0560] The solid aerosol-generating substrate may have a water content of from 17 to 35 percent by weight, from 17 to 30 percent by weight, or from 17 to 25 percent by weight, based on the total weight of the solid aerosol-generating substrate.

[0561] The solid aerosol-generating substrate may include one or more non-cellulosic thickeners.

[0562] As used herein, the term "non-cellulosic thickener" is used to describe a non-cellulosic substance that, when added to an aqueous or non-aqueous liquid composition, increases the viscosity of the liquid composition without substantially altering other properties of the liquid composition. One or more non-cellulosic thickeners may increase the stability and improve the suspension of ingredients in the liquid composition. A thickener may also be referred to as a "thickener" or "rheology modifier" or "viscosifying agent."

[0563] The solid aerosol-generating substrate may comprise one or more non-cellulosic thickeners selected from alginate, gellan gum, guar gum, gum arabic, locust bean gum, pectin, starch, and xanthan gum.

[0564] The solid aerosol-generating substrate may not contain iota- or kappa-carrageenan. Solid aerosol-generating substrates that do not contain iota- or kappa-carrageenan may advantageously remain solid when heated to temperatures between 180° C. and 350° C. This may advantageously reduce or eliminate crusting in aerosol-generating articles where the susceptor is in direct contact with the substrate.

[0565] The solid aerosol-generating substrate may be agar-free. Agar-free solid aerosol-generating substrate may advantageously remain solid when heated to temperatures between 180° C. and 350° C. This may advantageously reduce or eliminate crusting in aerosol-generating articles where the susceptor is in direct contact with the substrate.

[0566] The solid aerosol-generating substrate may have a total cellulosic thickener content of 1 weight percent or more, 2 weight percent or more, or 3 weight percent or more.

[0567] As used herein, the term "total non-cellulosic thickener content" is used to describe the combined content of all non-cellulosic thickeners in a solid aerosol-generating substrate.

[0568] The solid aerosol-generating substrate may have a total non-cellulosic thickener content of 10 weight percent or less, 8 weight percent or less, or 6 weight percent or less.

[0569] The solid aerosol-generating substrate may have a total non-cellulosic thickener content of from 1 weight percent to 10 weight percent, from 1 weight percent to 8 weight percent, or from 1 weight percent to 6 weight percent.

[0570] The solid aerosol-generating substrate may have a total non-cellulosic thickener content of from 2 weight percent to 10 weight percent, from 2 weight percent to 8 weight percent, or from 2 weight percent to 6 weight percent.

[0571] The solid aerosol-generating substrate may have a total non-cellulosic thickener content of from 3 weight percent to 10 weight percent, from 3 weight percent to 8 weight percent, or from 3 weight percent to 6 weight percent.

[0572] The solid aerosol-generating substrate may include one or more flavoring agents.

[0573] Suitable flavoring agents are known in the art and include, but are not limited to, menthol.

[0574] As used herein, the term "menthol" is used to describe the compound 2-isopropyl-5-methylcyclohexanol in any of its isomeric forms.

[0575] As used herein, the term "total flavorant content" is used to describe the combined content of all flavorants in a solid aerosol-generating substrate.

[0576] The solid aerosol-generating substrate may have a total flavorant content of 0.5 weight percent or more, 1 weight percent or more, 2 weight percent or more, or 3 weight percent or more.

[0577] The solid aerosol-generating substrate may have a total flavorant content of 6 weight percent or less, 5 weight percent or less, or 4 weight percent or less.

[0578] The solid aerosol-generating substrate may have a total flavorant content of from 0.5 weight percent to 6 weight percent, from 0.5 weight percent to 5 weight percent, or from 0.5 weight percent to 4 weight percent.

[0579] The solid aerosol-generating substrate may have a total flavorant content of from 1 weight percent to 6 weight percent, from 1 weight percent to 5 weight percent, or from 1 weight percent to 4 weight percent.

[0580] The solid aerosol-generating substrate may have a total flavorant content of from 2 to 6 percent by weight, from 2 to 5 percent by weight, or from 2 to 4 percent by weight.

[0581] The solid aerosol-generating substrate may have a total flavorant content of from 3 to 6 percent by weight, from 3 to 5 percent by weight, or from 3 to 4 percent by weight.

[0582] The solid aerosol-generating substrate may be a substantially tobacco-free solid aerosol-generating substrate.

[0583] As used herein, the term "substantially tobacco-free solid aerosol-generating substrate" is used to describe a solid aerosol-generating substrate having a tobacco content of less than 1 percent by weight. For example, the solid aerosol-generating substrate may have a tobacco content of less than 0.75 percent by weight, less than 0.5 percent by weight, or less than 0.25 percent by weight.

[0584] The solid aerosol-generating substrate may be a tobacco-free aerosol-generating film.

[0585] The term "tobacco-free solid aerosol-generating substrate" is used to describe a solid aerosol-generating substrate having zero weight percent tobacco content.

[0586] In a particularly preferred embodiment, the solid aerosol-generating substrate is a solid aerosol-generating film, glycerin in an amount of 35 weight percent to 62 weight percent; Carboxymethylcellulose in an amount of 2 weight percent to 12 weight percent; hydroxypropyl methylcellulose in an amount of 14 weight percent to 40 weight percent; a total cellulosic strengthening agent content in an amount of 2 weight percent to 30 weight percent; a total carboxylic acid content in an amount of 0.5 weight percent to 8 weight percent; Nicotine in an amount of 0.5 weight percent to 10 weight percent; and water in an amount of 5 weight percent to 35 weight percent.

[0587] In another embodiment, the aerosol-generating substrate may comprise thermally conductive particles. The aerosol-generating substrate may comprise 10 to 90 weight percent (wt%) of thermally conductive particles on a dry weight basis. The aerosol-generating substrate may comprise 7 to 60 wt% of aerosol formers on a dry weight basis. The aerosol-generating substrate may comprise 2 to 20 wt% of fibers on a dry weight basis. The aerosol-generating substrate may comprise 2 to 10 wt% of a binder on a dry weight basis. Each of the thermally conductive particles may be comprised of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond.

[0588] When the term "thermally conductive particles" is used to refer to particles that include carbon, such as particles that include or consist of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond, the thermally conductive particles may be referred to as carbon particles or carbon-containing particles.

[0589] Advantageously, the thermally conductive particles can increase the thermal conductivity of the aerosol-generating substrate. Increasing the thermal conductivity of the substrate can provide a more uniform temperature distribution throughout the substrate during use. This can increase the proportion of the aerosol-generating substrate that reaches a temperature high enough to release a volatile compound, and therefore, can increase the efficiency of use of the aerosol-generating substrate. Furthermore, increasing the thermal conductivity of the substrate can allow a heater, such as a heating blade configured to heat the substrate, to operate at a lower temperature and therefore require less power. Furthermore, increasing the thermal conductivity of the substrate can enable the heater to heat the substrate to a temperature that releases the volatile compound in a shorter time. Therefore, increasing the thermal conductivity can reduce the time required to form an aerosol that can be inhaled by a user.

[0590] Advantageously, one or both of the fibres and the binder may increase the tensile strength of the aerosol-generating substrate. Increased tensile strength may enable the production of sheets of the aerosol-generating substrate that do not tear easily. Increased tensile strength may enable the production of sheets of the aerosol-generating substrate using existing manufacturing machinery.

[0591] The aerosol-generating substrate may have a thermal conductivity of at least 0.05, 0.1, 0.15, 0.2, 0.22, 0.3, 0.4, or 0.5 W / (mK) at 25°C in at least one direction, or in all directions. This thermal conductivity may be measured when the moisture content of the substrate is 0-20%, or 5-15%, for example, about 10%. This thermal conductivity may be measured when the substrate contains 0-20% or 5-15% water by weight, for example, about 10% water by weight. The moisture content or water content of the substrate may be measured using a titration method. The moisture content or water content of the substrate may be measured using the Karl Fisher method.

[0592] Optionally, some or all of the thermally conductive particles comprise at least 10, 30, 50, 70, 90, 95, 98, or 99% carbon by weight.

[0593] Optionally, some or all of the thermally conductive particles are graphite particles. Optionally, some or all of the thermally conductive particles are expanded graphite particles. Optionally, some or all of the thermally conductive particles are graphene particles. Optionally, some or all of the thermally conductive particles are carbon nanotubes or carbon nanotube particles. Optionally, some or all of the thermally conductive particles are charcoal particles. Optionally, some or all of the thermally conductive particles are diamond particles, e.g., synthetic diamond particles. Advantageously, such materials have relatively high thermal conductivity.

[0594] The expanded graphite may have a density of less than 2, 1.8, 1.5, 1.2, 1, 0.8, or 0.5, 0.2, 0.1, 0.05, 0.02 grams per cubic centimeter (g / cm). The expanded graphite may have a density of greater than 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, or 1.8 grams per cubic centimeter (g / cm). Expanded graphite has the following concentrations per cubic centimeter: 0.01-3, 0.01-2, 0.01-1.8, 0.01-1.5, 0.01-1.2, 0.01-1, 0.01-0.8, 0.01-0.5, 0.02-3, 0.02-2, 0.02-1.8, 0.02-1.5, 0.02-1.2, 0.02-1, 0.02-0.8, 0.02-0.5, 0.01-3, 0.05-2, 0.05-1.8, 0.05-1.5, 0.05-1.2, 0.05-1, 0.05-0.8, 0.05-0.5g / cm3, 0.1 The density may be 0.5 to 3, 0.1 to 2, 0.1 to 1.8, 0.1 to 1.5, 0.1 to 1.2, 0.1 to 1, 0.1 to 0.8, 0.1 to 0.5, 0.2 to 3, 0.2 to 2, 0.2 to 1.8, 0.2 to 1.5, 0.2 to 1.2, 0.2 to 1, 0.2 to 0.8, 0.2 to 0.5, 0.5 to 3, 0.5 to 2, 0.5 to 1.8, 0.5 to 1.5, 0.5 to 1.2, 0.5 to 1, 0.5 to 0.8, 0.8 to 3, 0.8 to 2, 0.8 to 1.8, 0.8 to 1.5, 0.8 to 1.2, or 0.8 to 1 grams (g / cm3).

[0595] Optionally, if each of the thermally conductive particles does not necessarily consist of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond, some or all of the thermally conductive particles comprise a metal. Alternatively, or additionally, some or all of the thermally conductive particles comprise an alloy. Alternatively, or additionally, some or all of the thermally conductive particles comprise an intermetallic compound. Advantageously, such materials have relatively high thermal conductivity.

[0596] Optionally, when each of the thermally conductive particles does not necessarily consist of one or more of graphite, expanded graphite, graphene, carbon nanotubes, charcoal, and diamond, some or all of the thermally conductive particles comprise one or more of silicon carbide, silver, copper, gold, aluminum nitride, aluminum, tungsten, and boron nitride. Optionally, some or all of the thermally conductive particles are silicon carbide particles. Optionally, some or all of the thermally conductive particles are silver particles. Optionally, some or all of the thermally conductive particles are copper particles. Optionally, some or all of the thermally conductive particles are gold particles. Optionally, some or all of the thermally conductive particles are aluminum nitride particles. Optionally, some or all of the thermally conductive particles are aluminum particles. Optionally, some or all of the thermally conductive particles are tungsten particles. Optionally, some or all of the thermally conductive particles are boron nitride particles. Advantageously, such materials have relatively high thermal conductivity.

[0597] The thermally conductive particles may each have a “particle size.” The meaning of the term “particle size” and methods for measuring particle size will be explained below.

[0598] Thermally conductive particles can be characterized by a particle size distribution. The particle size distribution can have particle sizes designated D10, D50, and D90. The particle size designated D10 is defined as 10% of the particles having a particle size equal to or less than the particle size designated D10. Similarly, the particle size designated D50 is defined as 50% of the particles having a particle size equal to or less than the particle size designated D50. Thus, the particle size designated D50 can also be referred to as the median particle size. The particle size designated D90 is defined as 90% of the particles having a particle size equal to or less than the particle size designated D90. Thus, if there are 1,000 particles in a distribution, and the particles are arranged in order of decreasing size, the particle size designated D10 would be expected to be approximately equal to the particle size of the 100th particle, the particle size designated D50 would be approximately equal to the particle size of the 500th particle, and the particle size designated D90 would be approximately equal to the particle size of the 900th particle.

[0599] The particle size distribution can have particle sizes of volume D10, D50, and D90. The particle size of volume D10 is defined such that 10% of the total volume of all particles is occupied by the total volume of particles having a particle size equal to or less than the particle size of volume D10. Similarly, the particle size of volume D50 is defined such that 50% of the total volume of all particles is occupied by the total volume of particles having a particle size equal to or less than the particle size of volume D50. Furthermore, the particle size of volume D90 is defined such that 90% of the total volume of all particles is occupied by the total volume of particles having a particle size equal to or less than the particle size of volume D90.

[0600] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D10, where the particle size number D10 is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0601] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D10, where the particle size number D10 is less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0602] A compromise must be made when determining particle size. Advantageously, larger thermally conductive particles can significantly increase the thermal conductivity of the aerosol-generating substrate compared to smaller thermally conductive particles. However, larger thermally conductive particles can reduce the space available within the substrate for the aerosol-generating material.

[0603] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D50, where the particle size number D50 is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0604] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D50, where the particle size number D50 is less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0605] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D90, where the particle size number D90 is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0606] Optionally, the thermally conductive particles have a particle size distribution with a particle size number D90, where the particle size number D90 is less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0607] Optionally, the thermally conductive particles have a particle size distribution having a particle size number D10 and a particle size number D90, wherein the particle size number D90 is no greater than 50, 40, 30, 20, 10, or 5 times the particle size number D10.

[0608] Optionally, the thermally conductive particles have a particle size distribution having a particle size of a number D10 and a particle size of a number D90, wherein the particle size of the number D90 is at least 1.5, 2, 3, 5, 10, or 20 times larger than the particle size of the number D10.

[0609] A compromise must be made regarding particle size distribution. For example, a tighter particle size distribution, characterized by a smaller ratio between D90 and D10 particle sizes, can advantageously provide more uniform thermal conductivity throughout the aerosol-generating substrate. This is because there is less variation in particle size at different locations within the substrate. This can advantageously allow for more efficient use of the aerosol-generating material throughout the aerosol-generating substrate. However, a tighter particle size distribution can disadvantageously be more difficult and expensive to achieve. The inventors have found that the particle size distribution described above can provide an optimal compromise between these two factors.

[0610] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D10, wherein the particle size in volume D10 is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0611] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D10 that is less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0612] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D50, wherein the particle size in volume D50 is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0613] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D50, wherein the particle size in volume D50 is less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0614] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D90, wherein the particle size in volume D90 is at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns.

[0615] Optionally, the thermally conductive particles have a particle size distribution with a particle size in volume D90, wherein the particle size in volume D90 is less than or equal to 1,000, 500, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns.

[0616] It may be particularly preferred for the thermally conductive particles to have a particle size distribution with a particle size volume D10 of 1 to 20 microns. Alternatively, or additionally, it may be particularly preferred for the thermally conductive particles to have a particle size distribution with a particle size volume D90 of 50 to 300 microns, or 50 to 200 microns.

[0617] Optionally, the thermally conductive particles have a particle size distribution having a volume D10 particle size and a volume D90 particle size, wherein the volume D90 particle size is no greater than 50, 40, 30, 20, 10, or 5 times the volume D10 particle size.

[0618] Optionally, the thermally conductive particles have a particle size distribution having a volume D10 particle size and a volume D90 particle size, wherein the volume D90 particle size is at least 1.5, 2, 3, 5, 10, or 20 times the volume D10 particle size.

[0619] As explained above, a compromise has to be made with respect to particle size distribution, and the inventors have found that the particle size distribution described above may provide an optimum compromise.

[0620] Optionally, each of the thermally conductive particles has a particle size of at least 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 microns. Optionally, each of the thermally conductive particles has a particle size of 1,000, 500, 300, 200, 100, 50, 20, 10, 5, 2, 1, 0.5, or 0.2 microns or less. It may be particularly preferred for each of the thermally conductive particles to have a particle size of at least 1 micron. Alternatively, or additionally, it may be particularly preferred for each of the thermally conductive particles to have a particle size of 300 microns or less. Particles smaller than 1 micron may be difficult to handle during manufacturing. In addition, particles smaller than 1 micron may be more likely to pass through filters in aerosol-generating articles that include an aerosol-generating substrate. Particles larger than 300 microns may occupy a significant amount of space within a substrate that may be used for the aerosol-generating material. Therefore, it may be particularly advantageous for the thermally conductive particles each to have a particle size of at least 1 micron, or a particle size of 300 microns or less, or both.

[0621] Optionally, each of the thermally conductive particles has three mutually orthogonal dimensions, with the largest of the three dimensions being 10, 8, 5, 3, or 2 times or less than the smallest of the three dimensions. Optionally, each of the thermally conductive particles has three mutually orthogonal dimensions, with the largest of the three dimensions being 10, 8, 5, 3, or 2 times or less than the second largest of the three dimensions. Optionally, each of the thermally conductive particles is substantially spherical. Advantageously, the orientation of substantially spherical particles may not affect the thermal conductivity of the substrate as much as the orientation of non-spherical particles. Thus, the use of more spherical particles may result in reduced variation between different substrates where particle orientation is not controlled. Furthermore, substantially spherical particles may be easier to characterize.

[0622] Optionally, the thermally conductive particles comprise at least 10, 20, 50, 100, 200, 500, or 1000 particles. Advantageously, a greater number of particles in the aerosol-generating substrate may allow for more uniform thermal conductivity of the substrate.

[0623] Optionally, the substrate comprises at least 20, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85 wt. % thermally conductive particles on a dry weight basis. Optionally, the substrate comprises no more than 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15 wt. % thermally conductive particles on a dry weight basis. Optionally, the substrate comprises 10-90, 20-90, 30-90, 40-90, 50-90, 60-90, 70-90, 80-90, 10-80, 20-80, 30-80, 40-80, 50-80, 60-80, 70-80, 10-70, 20-70, 30-70, 40-70, 50-70, 60-70, 10-60, 20-60, 30-60, 40-60, 50-60, 10-50, 20-50, 30-50, 40-50, 10-40, 20-40, 30-40, 10-30, 20-30, or 10-20 weight percent thermally conductive particles on a dry weight basis. It may be particularly preferred for the substrate to comprise 50 to 90, or more preferably 60 to 90, or even more preferably 65 to 85 wt % thermally conductive particles on a dry weight basis.

[0624] A compromise must be made with the weight percentage of thermally conductive particles in the substrate. Increasing the weight percentage of particles in the aerosol-generating substrate can advantageously increase the thermal conductivity of the substrate. However, increasing the weight percentage of particles in the aerosol-generating substrate may also reduce the space available for one or more of the aerosol former, binder, and fibers, potentially resulting in a substrate that forms less aerosol or has lower tensile strength.

[0625] Optionally, the substrate comprises at least 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55% by weight of aerosol former on a dry weight basis. Optionally, the substrate comprises no more than 55, 50, 45, 40, 35, 30, 25, 20, or 15% by weight of aerosol former on a dry weight basis. Optionally, the substrate comprises 7-60, 10-60, 20-60, 30-60, 40-60, 50-60, 7-50, 10-50, 20-50, 30-50, 40-50, 7-40, 10-40, 20-40, 30-40, 7-30, 10-30, 20-30, 7-20, 10-20, or 7-10% by weight of aerosol former on a dry weight basis. It may be particularly preferred for the substrate to comprise 15 to 25 weight percent aerosol former on a dry weight basis.

[0626] Optionally, the aerosol former comprises or consists of one or more of polyhydric alcohols (such as propylene glycol, polyethylene glycol, triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monotriacetate, glycerol diacetate, or glycerol triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate). Optionally, the aerosol-generating substrate comprises one or both of glycerin and glycerol.

[0627] Optionally, the substrate comprises at least 2, 4, 6, 8, 10, 12, 14, 16, or 18 weight percent fibers on a dry weight basis. Optionally, the substrate comprises no more than 20, 18, 16, 14, 12, 10, 8, 6, or 4 weight percent fibers on a dry weight basis. Optionally, the substrate comprises 4-20, 6-20, 8-20, 10-20, 12-20, 14-20, 16-20, 18-20, 2-18, 4-18, 6-18, 8-18, 10-18, 12-18, 14-18, 16-18, 2-16, 4-16, 6-16, 8-16, 10 2-8, 4-8, 6-8, 2-6, 4-6, or 2-4 wt. % fibers. It may be particularly preferred for the substrate to comprise 2-10 wt. % fibers, on a dry weight basis.

[0628] Optionally, the fibers are cellulose fibers. Advantageously, cellulose fibers are not overly expensive and can increase the tensile strength of the substrate.

[0629] Optionally, each of the fibers has three mutually orthogonal dimensions, the largest of the three dimensions being at least 1.5, 2, 3, 5, 10, or 20 times greater than the smallest of the three dimensions. Optionally, each of the fibers has three mutually orthogonal dimensions, the largest of the three dimensions being at least 1.5, 2, 3, 5, 10, or 20 times greater than a second largest of the three dimensions.

[0630] Optionally, the substrate comprises at least 4, 6, or 8 wt% binder on a dry weight basis. Optionally, the substrate comprises no more than 8, 6, or 4 wt% binder on a dry weight basis. Optionally, the substrate comprises 4-10, 6-10, 8-10, 2-8, 4-8, 6-8, 2-6, 4-6, or 2-4 wt% binder on a dry weight basis. It may be particularly preferred for the substrate to comprise 2-10 wt% binder on a dry weight basis.

[0631] Suitable binders are known in the art and include, but are not limited to, natural pectins (such as fruit pectins, citrus pectins, or tobacco pectins), guar gums (such as hydroxyethyl guar and hydroxypropyl guar), locust bean gums (such as hydroxyethyl locust bean gum and hydroxypropyl locust bean gum), alginates, starches (such as modified or derivatized starches), celluloses (such as methylcellulose, ethylcellulose, ethylhydroxymethylcellulose, carboxymethylcellulose), tamarind gum, dextran, puralon, konjac flour, xanthan gum, and the like. It may be particularly preferred that the binder is or comprise guar. It may be particularly preferred that the binder comprise or consist of one or more of carboxymethylcellulose or hydroxypropylcellulose, or a gum such as guar gum.

[0632] Optionally, the thermally conductive particles are distributed substantially uniformly throughout the aerosol-generating substrate. Optionally, the aerosol former is distributed substantially uniformly throughout the aerosol-generating substrate. Optionally, the fibers are distributed substantially uniformly throughout the aerosol-generating substrate. Optionally, the binder is distributed substantially uniformly throughout the aerosol-generating substrate. Advantageously, a uniform distribution of the components of the substrate can result in the substrate having more spatially uniform properties. For example, substantially uniformly distributed thermally conductive particles can result in the substrate having a substantially uniform thermal conductivity. As another example, substantially uniformly distributed binder or fibers can result in the substrate having a substantially uniform tensile strength.

[0633] Optionally, the substrate comprises nicotine. Optionally, the substrate comprises at least 0.01, 1, 2, 3, or 4% by weight of nicotine on a dry weight basis. Optionally, the substrate comprises no more than 5, 4, 3, 2, or 1% by weight of nicotine on a dry weight basis. Optionally, the substrate comprises 0.01-5, 1-5, 2-5, 3-5, 4-5, 0.01-4, 1-4, 2-4, 3-4, 0.01-3, 1-3, 2-3, 0.01-2, 1-2, or 0.01-1% by weight of nicotine on a dry weight basis. It may be particularly preferred for the substrate to comprise 0.5-4% by weight of nicotine on a dry weight basis.

[0634] Optionally, the nicotine is distributed substantially homogeneously throughout the aerosol-generating substrate.

[0635] Optionally, the substrate comprises an acid. Optionally, the substrate comprises at least 0.01, 1, 2, 3, or 4 wt. % acid on a dry weight basis. Optionally, the substrate comprises no more than 5, 4, 3, 2, or 1 wt. % acid on a dry weight basis. Optionally, the substrate comprises 0.01-5, 1-5, 2-5, 3-5, 4-5, 0.01-4, 1-4, 2-4, 3-4, 0.01-3, 1-3, 2-3, 0.01-2, 1-2, or 0.01-1 wt. % acid on a dry weight basis. It may be particularly preferred for the substrate to comprise 0.5-5 wt. % acid on a dry weight basis.

[0636] Optionally, the acid comprises or consists of one or more of fumaric acid, lactic acid, benzoic acid, and levulinic acid.

[0637] Optionally, the acid is distributed substantially homogeneously throughout the aerosol-generating substrate.

[0638] Optionally, the substrate comprises at least one plant. Optionally, the substrate comprises at least 0.01, 1, 2, 5, 10, or 15% by weight, on a dry weight basis, of at least one plant. Optionally, the substrate comprises no more than 20, 15, 10, 5, 2, or 1% by weight, on a dry weight basis, of at least one plant. Optionally, the substrate comprises 0.01-20, 1-20, 2-20, 5-20, 10-20, 15-20, 0.01-15, 1-15, 2-15, 5-15, 10-15, 0.01-10, 1-10, 2-10, 5-10, 0.01-5, 1-5, 2-5, 0.01-2, 1-2, or 0.01-1% by weight, on a dry weight basis, of at least one plant. It may be particularly preferred for the substrate to comprise 1 to 15% by weight, on a dry weight basis, of at least one plant.

[0639] Optionally, the at least one plant comprises or consists of one or both of clove and rosmarinus.

[0640] Optionally, the at least one plant is distributed substantially homogeneously throughout the aerosol-generating substrate.

[0641] Optionally, the substrate comprises at least one flavorant. Optionally, the substrate comprises at least 0.1, 1, 2, or 5 wt. % of at least one flavorant on a dry weight basis. Optionally, the substrate comprises no more than 10, 5, 2, or 1 wt. % of at least one flavorant on a dry weight basis. Optionally, the substrate comprises 0.1-10, 1-10, 2-10, 5-10, 0.1-5, 1-5, 2-5, 0.1-2, 1-2, or 0.1-1 wt. % of at least one flavorant on a dry weight basis. It may be particularly preferred for the substrate to comprise 0.1-5 wt. % of at least one flavorant on a dry weight basis.

[0642] Optionally, the at least one flavourant is present as a coating, for example a coating on one or more other components of the aerosol-generating substrate. Alternatively, or additionally, the at least one flavourant is distributed substantially homogeneously throughout the aerosol-generating substrate.

[0643] Optionally, the aerosol-generating substrate comprises at least one organic material, such as tobacco. Optionally, the at least one organic material comprises one or more of herb leaves, tobacco leaves, tobacco stem fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco. Optionally, the at least one organic material is distributed substantially homogeneously throughout the aerosol-generating substrate.

[0644] The substrate may contain less than 10, 5, 3, 2 or 1% by weight of tobacco on a dry weight basis.Optionally, the aerosol-generating substrate is a tobacco-free aerosol-forming substrate.

[0645] Optionally, some or each of the thermally conductive particles may be inductively heatable, for example, to a temperature of at least 100, 150, or 200 degrees Celsius. Optionally, some or each of the thermally conductive particles may comprise or consist of one or more susceptor materials. Advantageously, this may enable the thermally conductive particles to be inductively heated. The thermally conductive particles may comprise or be the only susceptor material present within the aerosol-generating substrate or within the rod of the aerosol-generating substrate. That is, there may be cases where there are no susceptor elements present within the aerosol-generating substrate or within the rod of the aerosol-generating substrate, other than the thermally conductive particles or carbon particles.

[0646] Optionally, the aerosol-generating substrate has a thermal conductivity in at least one direction at 25 degrees Celsius of greater than 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.75, 1, 1.25, 1.5, 2, 5, 10, 20, 50, 100, 200, or 500 W / (mK).

[0647] Optionally, the aerosol-generating substrate has a viscosity of 1500, 1450, 1400, 1350, 1300, 1250, 1200, 1100, 1050, 1000, 950, 900, 850, 800, 850, 800, 750, 700, 650, or 600 kg / m 3Optionally, the aerosol-generating substrate has a density of between 600 and 1400 kg / m 3 , 800~1200kg / m 3 , or 900-1100 kg / m 3 Advantageously, reducing the density of the substrate may reduce the cost of shipping the substrate.

[0648] Optionally, the aerosol-generating substrate has a moisture content of 1 to 20, or 3 to 15% by weight. This moisture content may be measured after equilibration at 20 degrees Celsius and 50% relative humidity for 48 hours. Optionally, the aerosol-generating substrate comprises 1 to 20, or 3 to 15% by weight water. The moisture content or water content of the substrate may be measured using a titration method. The moisture content or water content of the substrate may be measured using the Karl Fisher method.

[0649] Optionally, the aerosol-generating substrate comprises or is in the form of one or more of cut filler, powder particles, granules, pellets, pieces, spaghetti, strips, threads, ribbons, or sheets. Optionally, the aerosol-generating substrate comprises or is in the form of one or more sheets or strips.

[0650] Optionally, the aerosol-generating substrate comprises or is in the form of one or more sheets, for example an assembly of sheets. Optionally, the aerosol-generating substrate comprises or is in the form of a plurality of strips.

[0651] Optionally, the or each sheet or strip has a thickness of at least 5, 10, 20, 50, 100, 150, or 200 microns. Optionally, the or each sheet or strip has a thickness of no more than 2000, 1000, 500, 400, 300, or 250 microns. Optionally, the or each sheet or strip has a thickness of 100-350 microns, or 150-300 microns.

[0652] Optionally, the or each sheet or strip has a width of at least 100, 200, 500, or 1000 microns. Optionally, the or each sheet or strip has a width of no more than 2000, 1000, 500, 400, 300, 250, or 200 microns. Optionally, the or each sheet or strip has a width of 100-2000 microns, or 500-1000 microns, or 600-1000 microns.

[0653] Optionally, the sheets or strips, or each, have a length of at least 100, 200, 500, 1000, 2000, or 3000 microns. Optionally, the sheets or strips, or each, have a length of no more than 6000, 5000, 3000, 2000, 1000, 500, or 200 microns. Optionally, the sheets or strips, or each, have a length of 100-6000 microns, or 500-5000 microns, or 1000-4000 microns.

[0654] Optionally, the sheet or strip, or each, has a density of at least 20, 50, or 100 g / m 2 Optionally, the sheet or strip, or each, has a basis weight of 300 g / m 2 Optionally, the sheet or strip, or each, has a basis weight of 20 to 300 g / m 2 , 50~250g / m 2 , or 100-250g / m 2 The sheet has a basis weight of .

[0655] Optionally, the sheet or strip, or each, has a density of at least 0.1, 0.2, 0.3, or 0.5 g / m 3 Optionally, the sheet or strip, or each, has a density of 2, 1.5, 1.2, or 1 g / m 3 Optionally, the sheet or strip, or each, has a density of 0.1 to 2 g / m 3 , 0.2~2g / m 3 , 0.3~2g / m 3, 0.3 to 1.5 g / m 3 , or 0.3 to 1.2 g / m 3 It has a density of

[0656] When the substrate comprises one or more collections of sheets, the or each collection of sheets can have a width of at least about 1, 2, 5, 10, 25, 50, or 100 mm.

[0657] The aerosol-generating substrate containing thermally conductive particles can be prepared by forming a slurry containing the thermally conductive particles, an aerosol former, fibers, and a binder; The aerosol-generating substrate may be formed by any suitable method, such as a method comprising casting and drying a slurry to form the aerosol-generating substrate or a precursor for formation into an aerosol-generating substrate.

[0658] Optionally, the slurry comprises water. Optionally, the slurry comprises 20-90, 30-90, 40-90, 40-85, 50-80, 60-80, or 60-75 wt % water.

[0659] Optionally, the slurry comprises an acid. Optionally, the acid comprises or consists of one or more of fumaric acid, lactic acid, benzoic acid, and levulinic acid.

[0660] Optionally, the slurry comprises nicotine.

[0661] Optionally, forming the slurry includes forming a first mixture. The first mixture may include an aerosol former. The first mixture may include fibers. The first mixture may include water. The first mixture may include an acid. The first mixture may include nicotine. Forming the slurry may include forming a second mixture. The second mixture may include thermally conductive particles. The second mixture may include a binder. Forming the slurry may include adding the second mixture to the first mixture to form a combined mixture.

[0662] Therefore, forming a slurry involves: forming a first mixture including an aerosol former, fibers, water, optionally an acid, and optionally nicotine; forming a second mixture comprising thermally conductive particles and a binder; and adding the second mixture to the first mixture to form a combined mixture.

[0663] The combined mixture can then be formed into a slurry, for example, by mixing.

[0664] Optionally, forming the first mixture includes providing an aerosol former, or a solution including an aerosol former and nicotine.

[0665] Optionally, forming the first mixture includes adding an acid to the aerosol former, or to a solution including the aerosol former and nicotine, to form a first pre-mixture.

[0666] Optionally, forming the first mixture includes adding water to the aerosol former, or to a solution including the aerosol former and nicotine, or to the first pre-mixture to form a second pre-mixture.

[0667] Optionally, forming the first mixture includes adding fibers to the second pre-mixture.

[0668] Optionally, forming the second mixture includes mixing thermally conductive particles with a binder.

[0669] Optionally, the method, e.g., forming a slurry, includes first mixing the combined mixture. Optionally, the first mixing is performed under a first pressure of 500, 400, 300, 250, or 200 mbar or less. Optionally, the first mixing is performed for 1 to 10 minutes, 2 to 8 minutes, or 3 to 6 minutes, e.g., about 4 minutes.

[0670] Optionally, the method, e.g., forming a slurry, includes a second mixing step after the first mixing step. Optionally, the second mixing step is performed under a second pressure that is less than the first pressure. Optionally, the second pressure is equal to or less than 500, 400, 300, 200, 150, or 100 mbar. Optionally, the second mixing step is performed for 5 to 120 seconds, 5 to 80 seconds, 5 to 40 seconds, or 10 to 30 seconds, e.g., about 20 seconds.

[0671] Optionally, casting the slurry includes casting the slurry onto a flat support, for example a steel flat support.

[0672] Optionally, after casting the slurry and before drying the slurry, the method includes setting the thickness of the slurry, for example, setting the thickness of the slurry to between 100 and 1200 microns, between 200 and 1000 microns, between 300 and 900 microns, between 500 and 700 microns, for example, about 600 microns.

[0673] Optionally, drying the slurry includes providing a stream of gas, such as air, over or through the slurry. Optionally, the stream of gas is heated. Optionally, the stream of gas is heated to a temperature of 100-160 degrees Celsius, or 120-140 degrees Celsius. Optionally, the stream of gas is provided for 1-10 minutes, or 2-5 minutes. Optionally, drying the slurry includes drying the slurry until the slurry has a moisture content of 1-20, 2-15, 2-10, or 3-7% by weight.

[0674] Optionally, the slurry is dried to form a precursor for formation into an aerosol-generating substrate, the precursor being a sheet of aerosol-generating material. Optionally, the method includes cutting the sheet of aerosol-generating material.

[0675] As used herein, the term "thermally conductive particles" may refer to particles having a thermal conductivity of greater than 0.3, preferably 0.5, or more preferably 1 W / (mK) in at least one direction at 25 degrees Celsius, for example, in all directions at 25 degrees Celsius. The particles may exhibit anisotropic or isotropic thermal conductivity.

[0676] As used herein, the term "expanded graphite" may refer to a graphite-based material or a material having a graphite-like structure. Expanded graphite may have carbon layers (e.g., similar to graphite) with larger spacing between the carbon layers than found between the carbon layers in regular graphite. Expanded graphite may also have carbon layers with elements or compounds interposed within the spaces between the carbon layers.

[0677] The term "particle size" as used herein may refer to a single dimension and can be used to characterize a given particle size. The dimension may be the diameter of a spherical particle that occupies the same volume as the given particle. All particle sizes and particle size distributions herein can be obtained using standard laser diffraction techniques. The particle sizes and particle size distributions described herein can be obtained using commercially available sensors, such as Sympatec's HELOS laser diffraction sensor.

[0678] As used herein, the term "density" may refer to true density unless otherwise specified. Thus, unless otherwise specified, the density of a powder or particles may refer to the true density of the powder or particles (rather than the bulk density of the powder or particles, which can vary significantly depending on how the powder or particles are handled). True density measurements can be performed using many standard methods, and these methods are often based on Archimedes' principle. When used to measure the true density of a powder, the most widely used method involves the powder being placed and weighed inside a container of known volume (a pycnometer). The pycnometer is then filled with a fluid of known density in which the powder is not soluble. The volume of the powder is determined by the difference between the volume indicated by the pycnometer and the volume of the added liquid (i.e., the volume of air displaced).

[0679] The wrapper surrounding the rod of aerosol-generating substrate can be a paper wrapper or a non-paper wrapper. Suitable paper wrappers for use in certain embodiments of the present invention are known in the art and include, but are not limited to, cigarette paper and filter plug wrap. Suitable non-paper wrappers for use in certain embodiments of the present invention are known in the art and include, but are not limited to, sheets of homogenized tobacco material. In certain preferred embodiments, the wrapper may be formed from a laminate material comprising multiple layers. Preferably, the wrapper is formed from an aluminum co-laminate sheet. The use of an aluminum-containing co-laminate sheet advantageously prevents combustion of the aerosol-generating substrate if the aerosol-generating substrate is to be ignited rather than heated in the intended manner.

[0680] In certain preferred embodiments according to the present invention, the elongated susceptor element is disposed substantially longitudinally within the rod of the aerosol-generating substrate and is in thermal contact with the aerosol-generating substrate.

[0681] As used herein, the term "susceptor element" refers to a material capable of converting electromagnetic energy into heat. When positioned within a varying electromagnetic field, induced eddy currents in the susceptor element cause the susceptor element to heat. When an elongated susceptor element is positioned in thermal contact with an aerosol-generating substrate, the aerosol-generating substrate is heated by the susceptor element.

[0682] The susceptor may be in direct contact with the aerosol-generating substrate. Inclusion of one or more carboxylic acids in the aerosol-generating substrate can advantageously reduce or prevent corrosion of the susceptor.

[0683] The susceptor may be located within an aerosol-generating rod that contains the aerosol-generating substrate.

[0684] The susceptor may be located within the aerosol-generating substrate.

[0685] The aerosol-generating substrate may at least partially surround the susceptor.

[0686] The aerosol-generating substrate may be disposed on a susceptor. For example, if the aerosol-generating substrate is a solid aerosol-generating film, the susceptor may be at least partially coated with the solid aerosol-generating film.

[0687] The susceptor may be at least partially embedded within the aerosol-generating substrate, for example, if the aerosol-generating substrate is an aerosol-generating gel, the susceptor may be at least partially embedded within the aerosol-generating gel.

[0688] The susceptor may be an elongated susceptor.

[0689] When used to refer to a susceptor element, the term "elongated" means that the susceptor element has a length dimension that is greater than its width dimension or its thickness dimension, for example, more than twice its width dimension or its thickness dimension.

[0690] The susceptor elements are disposed substantially longitudinally within the rod, meaning that the length dimension of the elongated susceptor elements is disposed approximately parallel to the longitudinal direction of the rod, for example, within ±10 degrees of parallel to the longitudinal direction of the rod. In a preferred embodiment, the elongated susceptor elements may be positioned at a radially central location within the rod and extend along the longitudinal axis of the rod.

[0691] Preferably, the susceptor element extends all the way to the downstream end of the rod of the aerosol-generating substrate. In some embodiments, the susceptor element may extend all the way to the upstream end of the rod of the aerosol-generating substrate. In particularly preferred embodiments, the susceptor element has substantially the same length as the rod of the aerosol-generating substrate, extending from the upstream end of the rod to the downstream end of the rod.

[0692] The susceptor elements are preferably in the form of pins, rods, strips, or blades.

[0693] The susceptor element preferably has a length of about 10 millimeters to about 14 millimeters, such as, for example, about 6 millimeters to about 18 millimeters, or about 8 millimeters to about 16 millimeters.

[0694] The susceptor may have a length that is substantially the same as the length of the solid aerosol-generating substrate, or substantially the same as the length of the aerosol-generating rod that includes the solid aerosol-generating substrate.

[0695] The susceptor may extend along the longitudinal axis of the aerosol-generating article.

[0696] The ratio of the length of the susceptor element to the overall length of the aerosol-generating article may be from about 0.20 to about 0.35.

[0697] Preferably, the ratio of the length of the susceptor element to the overall length of the aerosol-generating article is at least about 0.22, more preferably at least about 0.24, and even more preferably at least about 0.26. Preferably, the ratio of the length of the susceptor element to the overall length of the aerosol-generating article is less than about 0.34, more preferably less than about 0.32, and even more preferably less than about 0.30.

[0698] In some embodiments, the ratio between the length of the susceptor element and the overall length of the aerosol-generating article is preferably about 0.22 to about 0.34, more preferably about 0.24 to about 0.34, and even more preferably about 0.26 to about 0.34. In other embodiments, the ratio between the length of the susceptor element and the overall length of the aerosol-generating article is preferably about 0.22 to about 0.32, more preferably about 0.24 to about 0.32, and even more preferably about 0.26 to about 0.32. In further embodiments, the ratio between the length of the susceptor element and the overall length of the aerosol-generating article is preferably about 0.22 to about 0.30, more preferably about 0.24 to about 0.30, and even more preferably about 0.26 to about 0.30.

[0699] In a particularly preferred embodiment, the ratio of the length of the susceptor element to the overall length of the aerosol-generating article is about 0.27.

[0700] The susceptor may have any desired width, for example, the susceptor may have a width of 2 millimeters to 8 millimeters, 3 millimeters to 7 millimeters, or 4 millimeters to 6 millimeters.

[0701] The susceptor may have any desired thickness. For example, the susceptor may have a thickness of 30 micrometers to 90 micrometers, 40 micrometers to 80 micrometers, or 50 micrometers to 70 micrometers.

[0702] When the susceptor element has a constant cross-section, for example a circular cross-section, it has a preferred width or diameter of about 1 millimeter to about 5 millimeters.

[0703] When the susceptor elements have the form of strips or blades, the strips or blades preferably have a rectangular shape, preferably having a width of about 2 millimeters to about 8 millimeters, more preferably about 3 millimeters to about 5 millimeters. As an example, a susceptor element in the form of a blade strip may have a width of about 4 millimeters.

[0704] When the susceptor elements are in the form of strips or blades, the strips or blades preferably have a rectangular shape and a thickness of about 0.03 millimeters to about 0.15 millimeters, more preferably about 0.05 millimeters to about 0.09 millimeters. As an example, a susceptor element in the form of a blade strip may have a thickness of about 0.07 millimeters.

[0705] In a preferred embodiment, the elongated susceptor elements are in the form of strips or blades, preferably having a rectangular shape and a thickness of about 55 micrometers to about 65 micrometers.

[0706] More preferably, the elongated susceptor elements have a thickness of about 57 micrometers to about 63 micrometers. Even more preferably, the elongated susceptor elements have a thickness of about 58 micrometers to about 62 micrometers. In a particularly preferred embodiment, the elongated susceptor elements have a thickness of about 60 micrometers.

[0707] The elongated susceptor elements preferably have a length that is the same as or shorter than the length of the aerosol-generating substrate.The elongated susceptor elements preferably have the same length as the aerosol-generating substrate.

[0708] The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from a solid aerosol-generating substrate.

[0709] The susceptor preferably comprises a metal, an alloy or carbon.

[0710] Suitable susceptor materials include, but are not limited to, carbon, carbon-based materials, graphene, graphite, expanded graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. The susceptor may comprise or consist of a ferromagnetic material (e.g., ferromagnetic alloys, ferritic iron, or ferromagnetic steel or stainless steel). Suitable susceptors may comprise or consist of aluminum. The susceptor material preferably comprises more than 5 percent ferromagnetic or paramagnetic material, more preferably more than 20 percent ferromagnetic or paramagnetic material, and more preferably more than 50 percent or more than 90 percent ferromagnetic or paramagnetic material. Preferred susceptor materials may comprise metals, metal alloys, or carbon.

[0711] The susceptor may be formed from 400 series stainless steel, such as grade 410 stainless steel, or grade 420 stainless steel, or grade 430 stainless steel. Different materials dissipate different amounts of energy when placed in electromagnetic fields having similar values ​​of frequency and field strength.

[0712] The susceptor may be or include carbon, a carbon-based material, graphene, graphite, or expanded graphite. Advantageously, such materials have relatively high thermal conductivity, relatively low density, and may be inductively heated.

[0713] Thus, any of the susceptor element parameters, such as type of material, length, width, and thickness, can be varied to provide a desired power distribution within a known electromagnetic field. Preferred susceptor elements may be heated to temperatures in excess of 250 degrees Celsius.

[0714] Suitable susceptor elements may include a non-metallic core having a metal layer, such as a metal band formed on the surface of the ceramic core. The susceptor element may have a protective outer layer, such as a protective ceramic or glass layer, encapsulating the susceptor element. The susceptor element may include a protective coating formed of glass, ceramic, or an inert metal formed over a core of susceptor element material.

[0715] The susceptor element is disposed in thermal contact with the aerosol-generating substrate, such that as the temperature of the susceptor element increases, the aerosol-generating substrate is heated and an aerosol is formed. Preferably, the susceptor element is disposed in direct physical contact with the aerosol-generating substrate, for example, within the aerosol-generating substrate.

[0716] The susceptor element may be a multi-material susceptor element and may comprise a first susceptor element material and a second susceptor element material. The first susceptor element material is disposed in close physical contact with the second susceptor element material. The second susceptor element material preferably has a Curie temperature below 500 degrees Celsius. The first susceptor element material is preferably primarily used to heat the susceptor element when the susceptor element is placed in a fluctuating electromagnetic field. Any suitable material may be used. For example, the first susceptor element material may be aluminum or an iron-based material such as stainless steel. The second susceptor element material is preferably primarily used to indicate when the susceptor element reaches a specific temperature, which is the Curie temperature of the second susceptor element material. The Curie temperature of the second susceptor element material can be used to regulate the temperature of the entire susceptor element during operation. Therefore, the Curie temperature of the second susceptor element material should be below the ignition point of the aerosol-generating substrate. Suitable materials for the second susceptor element material may include nickel and certain nickel alloys.

[0717] The heating of the aerosol-generating substrate and the temperature control of the heating can be separated by providing a susceptor element having at least first and second susceptor element materials with a second susceptor element material having a Curie temperature and a first susceptor element material having no Curie temperature, or by providing first and second susceptor element materials having different first and second Curie temperatures. The first susceptor element material is preferably a magnetic material having a Curie temperature greater than 500°C. From the standpoint of heating efficiency, it is desirable that the Curie temperature of the first susceptor element material exceed any maximum temperature to which the susceptor element can be heated. The second Curie temperature may be selected to be preferably lower than 400°C, preferably lower than 380°C, or even lower than 360°C. The second susceptor element material is preferably a magnetic material selected to have a second Curie temperature substantially equal to the desired maximum heating temperature. That is, the second Curie temperature is preferably approximately the same as the temperature to which the susceptor element must be heated to generate an aerosol from the aerosol-generating substrate. The second Curie temperature may be, for example, within the range of 200° C. to 400° C., or within the range of 250° C. to 360° C. The second Curie temperature of the second susceptor element material may be selected, for example, such that the overall average temperature of the aerosol-generating substrate does not exceed 240° C. when heated by a susceptor element having a temperature equal to the second Curie temperature.

[0718] In some embodiments, the aerosol-generating section of the aerosol-generating article of the present invention may include one or more upstream segments located upstream of the rod of the aerosol-generating substrate. In some embodiments, the aerosol-generating section may further include an upstream segment located immediately upstream of and adjacent to the rod of the aerosol-generating substrate. The upstream segment may abut the rod of the aerosol-generating substrate. The upstream segment advantageously prevents direct physical contact with the upstream end of the aerosol-generating substrate. Specifically, if the aerosol-generating substrate includes a susceptor element, the upstream segment may prevent direct physical contact with the upstream end of the susceptor element. This helps to prevent displacement or deformation of the susceptor element during handling or transportation of the aerosol-generating article. This, in turn, helps to fix the shape and position of the susceptor element. Furthermore, the presence of the upstream segment helps to prevent any loss of the substrate, which may be advantageous, for example, when the substrate contains particulate plant material.

[0719] The upstream segment can also provide an improved appearance to the upstream end of the aerosol-generating article. Furthermore, if desired, the upstream segment can be used to provide information about the aerosol-generating article, such as information about the brand, flavor, content, or details of the aerosol-generating device in which the article is intended to be used.

[0720] The upstream segment may be a porous plug element. Preferably, the porous plug element does not alter the withdrawal resistance of the aerosol-generating article. Preferably, the upstream segment has a porosity of at least about 50 percent along the longitudinal axis of the aerosol-generating article. More preferably, the upstream segment has a porosity of between about 50 percent and about 90 percent along the longitudinal axis. The longitudinal porosity of the upstream segment is defined as the ratio of the cross-sectional area of ​​the material forming the upstream segment to the internal cross-sectional area of ​​the aerosol-generating article at the location of the upstream segment.

[0721] The upstream segment may be made of a porous material or may include a plurality of openings, which may be achieved, for example, by laser drilling, preferably uniformly distributed across the cross section of the upstream segment.

[0722] The porosity or permeability of the upstream segment may be advantageously varied to provide a desired overall resistance to withdrawal of the aerosol-generating article.

[0723] Preferably, the RTD of the upstream segment is at least about 5 millimeters of HO. More preferably, the RTD of the upstream segment is at least about 10 millimeters of HO. Even more preferably, the RTD of the upstream segment is at least about 15 millimeters of HO. In particularly preferred embodiments, the RTD of the upstream segment is at least about 20 millimeters of HO.

[0724] The RTD of the upstream segment is preferably about 80 millimeters of H2O or less. More preferably, the RTD of the upstream segment is about 60 millimeters of H2O or less. Even more preferably, the RTD of the upstream segment is about 40 millimeters of H2O or less.

[0725] In some embodiments, the RTD of the upstream segment is between about 5 millimeters of HO and about 80 millimeters of HO, preferably between about 10 millimeters of HO and about 80 millimeters of HO, more preferably between about 15 millimeters of HO and about 80 millimeters of HO, and even more preferably between about 20 millimeters of HO and about 80 millimeters of HO. In other embodiments, the RTD of the upstream segment is between about 5 millimeters of HO and about 60 millimeters of HO, preferably between about 10 millimeters of HO and about 60 millimeters of HO, more preferably between about 15 millimeters of HO and about 60 millimeters of HO, and even more preferably between about 20 millimeters of HO and about 60 millimeters of HO. In further embodiments, the RTD of the upstream segment is between about 5 millimeters of HO and about 40 millimeters of HO, preferably between about 10 millimeters of HO and about 40 millimeters of HO, more preferably between about 15 millimeters of HO and about 40 millimeters of HO, and even more preferably between about 20 millimeters of HO and about 40 millimeters of HO.

[0726] In alternative embodiments, the upstream segment may be formed from a material that is impermeable to air. In such embodiments, the aerosol-generating article may be configured to allow air to flow into the rod of aerosol-generating substrate through suitable venting means provided in the wrapper.

[0727] The upstream segment may be made of any material suitable for use in an aerosol-generating article. The upstream segment may be made of the same material as that used in one of the other components of the aerosol-generating article, such as the mouthpiece, cooling segment, or support segment. Suitable materials for forming the upstream segment include filter material, ceramic, polymeric material, cellulose acetate, cardboard, zeolite, or an aerosol-generating substrate. The upstream segment is preferably formed from a plug of cellulose acetate.

[0728] The upstream segment is preferably formed from a heat resistant material, for example, a material that can withstand temperatures up to 350 degrees Celsius, to ensure that the upstream segment is not adversely affected by the heating means used to heat the aerosol-generating substrate.

[0729] Preferably, the upstream segment has a diameter approximately equal to the diameter of the aerosol-generating article.

[0730] Preferably, the upstream segment has a length of about 1 millimeter to about 10 millimeters, more preferably about 3 millimeters to about 8 millimeters, and even more preferably about 4 millimeters to about 6 millimeters. In a particularly preferred embodiment, the upstream segment has a length of about 5 millimeters. The length of the upstream segment can be advantageously varied to provide a desired overall length for the aerosol-generating article. For example, if it is desired to reduce the length of one of the other components of the aerosol-generating article, the length of the upstream segment can be increased to maintain the same overall length of the article.

[0731] The upstream segment preferably has a substantially homogeneous structure. For example, the upstream segment can be substantially homogeneous in texture and appearance. The upstream segment may, for example, have a continuous, regular surface across its entire cross section. The upstream segment may, for example, not have any discernible symmetry.

[0732] The upstream segment is preferably surrounded by a wrapper that is preferably a stiff plug wrap, such as a plug wrap having a basis weight of at least about 80 grams per square meter (gsm), or at least about 100 gsm, or at least about 110 gsm, to provide structural rigidity to the upstream segment.

[0733] Aerosol-generating articles according to the present invention may have a length of from about 35 millimeters to about 100 millimeters.

[0734] Preferably, the overall length of an aerosol-generating article according to the present invention is at least about 38 millimeters. More preferably, the overall length of an aerosol-generating article according to the present invention is at least about 40 millimeters. Even more preferably, the overall length of an aerosol-generating article according to the present invention is at least about 42 millimeters.

[0735] Preferably, the overall length of an aerosol-generating article according to the present invention is 70 mm or less, more preferably 60 mm or less, and even more preferably 50 mm or less.

[0736] In some embodiments, the total length of the aerosol-generating article is preferably between about 38 millimeters and about 70 millimeters, more preferably between about 40 millimeters and about 70 millimeters, and even more preferably between about 42 millimeters and about 70 millimeters. In other embodiments, the total length of the aerosol-generating article is preferably between about 38 millimeters and about 60 millimeters, more preferably between about 40 millimeters and about 60 millimeters, and even more preferably between about 42 millimeters and about 60 millimeters. In further embodiments, the total length of the aerosol-generating article is preferably between about 38 millimeters and about 50 millimeters, more preferably between about 40 millimeters and about 50 millimeters, and even more preferably between about 42 millimeters and about 50 millimeters. In an exemplary embodiment, the total length of the aerosol-generating article is about 45 millimeters.

[0737] Preferably, the aerosol-generating article has an outer diameter of at least 5 millimeters. Preferably, the aerosol-generating article has an outer diameter of at least 6 millimeters. More preferably, the aerosol-generating article has an outer diameter of at least 7 millimeters.

[0738] Preferably, the aerosol-generating article has an outer diameter of about 12 millimeters or less. More preferably, the aerosol-generating article has an outer diameter of about 10 millimeters or less. Even more preferably, the aerosol-generating article has an outer diameter of about 8 millimeters or less.

[0739] In some embodiments, the aerosol-generating article has an outer diameter of about 5 mm to about 12 mm, preferably about 6 mm to about 12 mm, and more preferably about 7 mm to about 12 mm. In other embodiments, the aerosol-generating article has an outer diameter of about 5 mm to about 10 mm, preferably about 6 mm to about 10 mm, and more preferably about 7 mm to about 10 mm. In further embodiments, the aerosol-generating article has an outer diameter of about 5 mm to about 8 mm, preferably about 6 mm to about 8 mm, and more preferably about 7 mm to about 8 mm.

[0740] In certain preferred embodiments of the present invention, the diameter of the aerosol-generating article at its downstream end (D DE ) is the diameter of the aerosol-generating article at the upstream end (D UE ) is (preferably) greater than the ratio between the diameter of the aerosol-generating article at its downstream end and the diameter of the aerosol-generating article at its upstream end (D DE / D UE ) is (preferably) at least about 1.005.

[0741] Preferably, the ratio between the diameter of the aerosol-generating article at its downstream end and the diameter of the aerosol-generating article at its upstream end (D DE / D UE ) is (preferably) at least about 1.01. More preferably, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE ) is at least about 1.02. Even more preferably, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE) is at least about 1.05.

[0742] The ratio between the diameter of the aerosol-generating article at its downstream end and the diameter of the aerosol-generating article at its upstream end (D DE / D UE ) is preferably about 1.30 or less. More preferably, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE ) is about 1.25 or less. Even more preferably, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE ) is about 1.20 or less. In particularly preferred embodiments, the ratio between the diameter of the aerosol-generating article at its downstream end and the diameter of the aerosol-generating article at its upstream end (D DE / D UE ) is less than or equal to 1.15 or 1.10.

[0743] In some preferred embodiments, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE ) is about 1.01 to 1.30, more preferably 1.02 to 1.30, and even more preferably 1.05 to 1.30.

[0744] In another embodiment, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE ) is about 1.01 to 1.25, more preferably 1.02 to 1.25, and even more preferably 1.05 to 1.25. In a further embodiment, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE ) is about 1.01 to 1.20, more preferably 1.02 to 1.20, and even more preferably 1.05 to 1.20. In still further embodiments, the ratio between the diameter of the aerosol-generating article at the downstream end and the diameter of the aerosol-generating article at the upstream end (D DE / D UE) is about 1.01 to 1.15, more preferably 1.02 to 1.15, and even more preferably 1.05 to 1.15.

[0745] By way of example, the outer diameter of the article may be substantially constant over a distal portion of the article extending at least about 5 millimeters or at least about 10 millimeters from the upstream end of the aerosol-generating article. Alternatively, the outer diameter of the article may taper over a distal portion of the article extending at least about 5 millimeters or at least about 10 millimeters from the upstream end.

[0746] In certain preferred embodiments of the present invention, as described above, the elements of the aerosol-generating article are arranged so that the center of mass of the aerosol-generating article is at least about 60 percent along the length of the aerosol-generating article from the downstream end, more preferably the elements of the aerosol-generating article are arranged so that the center of mass of the aerosol-generating article is at least about 62 percent along the length of the aerosol-generating article from the downstream end, and more preferably at least about 65 percent along the length of the aerosol-generating article from the downstream end.

[0747] The center of mass is preferably no more than about 70 percent along the length of the aerosol-generating article from the downstream end.

[0748] Providing an arrangement of elements that provides a center of mass closer to the upstream end than the downstream end results in an aerosol-generating article with a weight imbalance, with the upstream end being heavier. This weight imbalance can advantageously provide tactile feedback to the consumer, allowing them to distinguish between the upstream and downstream ends and insert the correct end into the aerosol generating device. This can be particularly beneficial when the upstream elements are provided such that the upstream and downstream ends of the aerosol-generating article visually resemble each other.

[0749] In embodiments of the aerosol-generating article according to the invention, both the aerosol-cooling segment and the support segment are present in the intermediate hollow section, and these are preferably wrapped together in a combined wrapper that surrounds the aerosol-cooling segment and the support segment, but does not surround any further downstream segments, such as the mouthpiece filter segment.

[0750] In these embodiments, the aerosol-cooling segment and the support segment are combined before being surrounded by a combined wrapper, which is then further combined with the mouthpiece filter segment.

[0751] From a manufacturing standpoint, this is advantageous in that it allows shorter aerosol-generating articles to be constructed.

[0752] In general, it can be difficult to handle individual elements with lengths smaller than their diameters. For example, for a 7-millimeter diameter element, a length of about 7 millimeters represents a threshold that is desirable to remain constant. However, a 10-millimeter aerosol-cooling element can be combined with a pair of 7-millimeter support elements on each side (and potentially with other elements, such as aerosol-generating substrate rods) to provide a 24-millimeter hollow segment, which can then be cut into two intermediate 12-millimeter hollow sections.

[0753] In a particularly preferred embodiment, the other components of the aerosol-generating article are individually surrounded by their own wrappers. In other words, the upstream element, the aerosol-generating substrate rod, the support segment, and the aerosol-cooling segment are all individually wrapped. The support segment and the aerosol-cooling segment are combined to form the intermediate hollow section. This is achieved by wrapping the support segment and the aerosol-cooling segment in a combined wrapper. The upstream segment, the aerosol-generating substrate rod, and the intermediate hollow section are then combined together with an outer wrapper. They are then combined with the mouthpiece section, which has its own wrapper, using tipping paper.

[0754] Preferably, at least one of the components of the aerosol-generating article is packaged in a hydrophobic wrapper.

[0755] The term "hydrophobicity" refers to a surface that exhibits water-repellent properties. One useful way to determine this is to measure the water contact angle. The "water contact angle" is the angle traditionally measured through a liquid where the liquid / vapor interface meets a solid surface. The water contact angle quantifies the wettability of a solid surface by a liquid via Young's equation. Hydrophobicity or water contact angle can be determined by utilizing the TAPPI T558 test method, with results expressed as interfacial contact angle, reported in degrees, and can range from approximately zero to approximately 180 degrees.

[0756] In a preferred embodiment, the hydrophobic wrapper is a wrapper that includes a paper layer that has a water contact angle of about 30 degrees or greater, preferably about 35 degrees or greater, or about 40 degrees or greater, or about 45 degrees or greater.

[0757] By way of example, the paper layer may comprise PVOH (polyvinyl alcohol) or silicone. The PVOH may be applied to the paper layer as a surface coating, or the paper layer may include a surface treatment that includes PVOH or silicone.

[0758] In a particularly preferred embodiment, an aerosol-generating article according to the invention comprises, in a linear continuous arrangement, an upstream segment, a rod of aerosol-generating substrate located immediately downstream of the upstream segment, a support segment located immediately downstream of the rod of aerosol-generating substrate, an aerosol-cooling segment located immediately downstream of the support segment, a mouthpiece filter segment located immediately downstream of the aerosol-cooling segment, and an outer wrapper surrounding the upstream segment, the rod of aerosol-generating substrate, the support segment, the aerosol-cooling segment, and the mouthpiece filter segment.

[0759] More particularly, the rod of the aerosol-generating substrate may abut the upstream segment. The support segment may abut the rod of the aerosol-generating substrate. The aerosol-cooling segment may abut the support segment. The mouthpiece segment may abut the aerosol-cooling segment.

[0760] The aerosol-generating article has a substantially cylindrical shape and an outer diameter of about 7.25 millimeters.

[0761] The upstream segment has a length of about 5 mm, the aerosol-generating substrate rod has a length of about 12 mm, the support segment has a length of about 8 mm, the aerosol-cooling segment has a length of about 13 mm, and the mouthpiece filter segment has a length of about 7 mm, so the total length of the aerosol-generating article is about 45 mm.

[0762] The upstream segment is in the form of a plug of cellulose acetate encased in a stiff plug wrap.

[0763] The aerosol-generating article comprises an elongated susceptor element disposed substantially longitudinally within and in thermal contact with the rod of aerosol-generating substrate, the susceptor element being in the form of a strip or blade having a length substantially equal to the length of the rod of aerosol-generating substrate and a thickness of about 60 micrometers.

[0764] The support segment is in the form of a hollow cellulose acetate tube having an inside diameter of about 1.9 millimeters, so that the peripheral wall thickness of the support element is about 2.675 millimeters.

[0765] The aerosol cooling segment is in the form of a finer hollow cellulose acetate tube with an inner diameter of about 3.25 millimeters, so the peripheral wall thickness of the aerosol cooling element is about 2 millimeters.

[0766] The mouthpiece is in the form of a low density cellulose acetate filter segment.

[0767] The aerosol-generating rod comprises at least one of the aerosol-generating substrates of the types described above, such as homogenized tobacco, a gel formulation, or homogenized plant material consisting of particles of a plant other than tobacco, an aerosol-generating film, or thermally conductive particles.

[0768] The present invention will now be further described with reference to the accompanying Figures 1 and 2, which show schematic cross-sectional side views of an aerosol-generating article according to the present invention.

[0769] The aerosol-generating article 10 shown in Figure 1 includes an aerosol-generation section 52, an intermediate hollow section 50, and a mouthpiece section 64. The aerosol-generation section includes a rod of aerosol-generating substrate 12 and an upstream segment 16 located upstream of the rod of aerosol-generating substrate 12.

[0770] The aerosol-generating article has a total length of about 45 millimeters.

[0771] The aerosol-generating article 10 extends from an upstream or distal end 18 to a downstream or mouth end 20. The aerosol-generating article includes an aerosol-generating substrate rod 12 and a downstream section 14 located downstream of the aerosol-generating substrate rod 12. The downstream section 14 includes a support segment 22 located immediately downstream of the aerosol-generating substrate rod 12, the support segment 22 being longitudinally aligned with the rod 12. In the embodiment of FIG. 1, an upstream end 30 of the support segment 22 abuts the downstream end of the aerosol-generating substrate rod 12. The downstream section 14 further includes an aerosol-cooling segment 24 located immediately downstream of the support segment 22, the aerosol-cooling segment 24 being longitudinally aligned with the rod 12 and the support segment 22. In the embodiment of FIG. 1, an upstream end 38 of the aerosol-cooling segment 24 abuts the downstream end of the support segment 22.

[0772] As will become apparent from the following description, the support segment 22 and the aerosol-cooling segment 24 together define an intermediate hollow section 50 of the aerosol-generating article 10. As a whole, the intermediate hollow section 50 does not contribute substantially to the overall RTD of the aerosol-generating article. The RTD of the intermediate hollow section 50 as a whole is substantially 0 millimeters HO.

[0773] The support segment 22 includes a first hollow tubular segment 26. The first hollow tubular segment 26 is provided in the form of a hollow cylindrical tube made from cellulose acetate. The first hollow tubular segment 26 defines an interior cavity 28 that extends entirely from the upstream end 30 of the first hollow tubular segment to the downstream end 32 of the first hollow tubular segment 20. The interior cavity 28 is substantially empty, thus allowing substantially unrestricted airflow along the interior cavity 28. The first hollow tubular segment 26, and consequently the support segment 22, does not substantially contribute to the overall RTD of the aerosol-generating article 10. More specifically, the RTD of the first hollow tubular segment 26 (which is substantially the RTD of the support segment 22) is substantially 0 millimeters HO.

[0774] The first hollow tubular segment 26 has a length of about 8 millimeters, an outer diameter of about 7.25 millimeters, and an inner diameter (D FTS ) The peripheral wall thickness of the first hollow tubular segment 26 is therefore approximately 2.67 millimeters.

[0775] The aerosol cooling segment 24 includes a second hollow tubular segment 34. The second hollow tubular segment 34 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The second hollow tubular segment 34 defines an interior cavity 36 extending from an upstream end 38 of the second hollow tubular segment all the way to a downstream end 40 of the second hollow tubular segment 34. The interior cavity 36 is substantially empty, thereby allowing substantially unrestricted airflow along the interior cavity 36. The second hollow tubular segment 34, and consequently the aerosol cooling segment 24, does not substantially contribute to the overall RTD of the aerosol-generating article 10. More specifically, the RTD of the second hollow tubular segment 34 (which is essentially the RTD of the aerosol cooling element 24) is substantially 0 millimeters HO.

[0776] The second hollow tubular segment 34 has a length of about 13 millimeters, an outer diameter of about 7.25 millimeters, and an inner diameter (D STS ) of the first hollow tubular segment 26. Therefore, the thickness of the peripheral wall of the second hollow tubular segment 34 is about 2 millimeters. FTS ) and the inner diameter (D STS ) is about 0.75.

[0777] The aerosol-generating article 10 includes a ventilation zone 60 provided at a location along the second hollow tubular segment 34. More specifically, the ventilation zone is provided approximately 2 millimeters from the upstream end of the second hollow tubular segment 34. The ventilation level of the aerosol-generating article 10 is approximately 25 percent.

[0778] 1, downstream section 14 further comprises a mouthpiece segment 42 located downstream of intermediate hollow section 50. More particularly, mouthpiece filter segment 42 is positioned immediately downstream of aerosol cooling element 24. As shown in the drawing of FIG. 1, the upstream end of mouthpiece filter segment 42 abuts downstream end 40 of aerosol cooling element 18.

[0779] The mouthpiece filter segment 42 is provided in the form of a cylindrical plug of low density cellulose acetate.

[0780] Mouthpiece filter segment 42 has a length of approximately 7 millimeters and an outer diameter of approximately 7.25 millimeters. The RTD of mouthpiece filter segment 42 is approximately 7 millimeters HO. The ratio of the length of mouthpiece filter segment 42 to the length of intermediate hollow section 50 is approximately 0.33.

[0781] The rod 12 includes an aerosol-generating substrate of one of the types described above.

[0782] The aerosol-generating substrate rod 12 has an outer diameter of about 7.25 millimeters and a length of about 12 millimeters.

[0783] The aerosol-generating article 10 further comprises an elongated susceptor element 44 within the aerosol-generating substrate rod 12. More specifically, the susceptor element 44 is disposed substantially longitudinally within the aerosol-generating substrate, generally parallel to the longitudinal direction of the rod 12. As shown in the drawing in Figure 1, the susceptor element 44 is positioned at a radially central location within the rod and effectively extends along the longitudinal axis of the rod 12.

[0784] The susceptor element 44 extends completely from the upstream end to the downstream end of the rod 12. In practice, the susceptor element 44 has substantially the same length as the rod 12 of the aerosol-generating substrate.

[0785] In the embodiment of Figure 1, the susceptor element 44 is provided in the form of a strip, having a length of approximately 12 millimeters, a thickness of approximately 60 micrometers, and a width of approximately 4 millimeters. The upstream section 16 includes an upstream element 46 located immediately upstream of the aerosol-generating substrate rod 12, the upstream element 46 being longitudinally aligned with the rod 12. In the embodiment of Figure 1, the downstream end of the upstream element 46 abuts the upstream end of the aerosol-generating substrate rod 12. This advantageously prevents the susceptor element 44 from becoming dislodged. This further ensures that consumers cannot accidentally come into contact with the heated susceptor element 44 after use.

[0786] The upstream segment 46 is provided in the form of a cylindrical plug of cellulose acetate surrounded by a hard wrapper. The upstream segment 46 has a length of approximately 5 millimeters. The RTD of the upstream element 46 is approximately 30 millimeters HO.

[0787] FIG. 2 shows an aerosol-generating article 100, which is a variation of the aerosol-generating article 10 described above. The aerosol-generating article 100 differs from the aerosol-generating article 10 by providing an additional aerosol-cooling segment 58, including a third hollow tubular segment 54. Accordingly, the intermediate hollow section 50 includes the support segment 22, the aerosol-cooling segment 24, and the additional aerosol-cooling segment 58. The hollow tubular segment 54 is provided in the form of a hollow cylindrical tube made from cellulose acetate. The third hollow tubular segment 54 defines an internal cavity 56. The third hollow tubular segment 54 abuts the upstream end 62 of the mouthpiece filter 42. The internal cavity 56 is substantially empty, so that substantially unrestricted airflow is possible along the internal cavity 56. The third hollow tubular segment 54, and consequently the additional aerosol-cooling segment 58, do not substantially contribute to the overall RTD of the aerosol-generating article 100. More particularly, the RTD of the third hollow tubular segment 54 (which is essentially the RTD of the aerosol cooling element 58) is substantially 0 millimeters H2O.

[0788] In this embodiment of article 100, second hollow tubular segment 34 has a length of approximately 8 millimeters and third hollow tubular segment 54 has a length of approximately 5 millimeters.

Claims

1. 1. An aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article extending from a downstream end to an upstream end; an aerosol-generation section including a rod of aerosol-generating substrate; a mouthpiece section including a mouthpiece filter segment formed of a fibrous filtration material, the mouthpiece section having a length L1 extending between an upstream end of the mouthpiece filter segment and a downstream end of the aerosol-generating article; an intermediate hollow section having a length L2 extending between the aerosol-generation section and the mouthpiece section, the intermediate hollow section defining a longitudinal cavity that provides an unrestricted flow channel from the aerosol-generation section to the mouthpiece section, the intermediate hollow section comprising: an aerosol cooling segment downstream of the aerosol-generation section; and an intermediate hollow section including a support segment between the aerosol-cooling segment and the aerosol-generation section; An aerosol-generating article wherein the length (L1) of the mouthpiece section is at least 0.10 times and less than 0.34 times the length (L2) of the intermediate hollow section.

2. 2. The aerosol-generating article of claim 1, wherein the length of the mouthpiece section is at least 0.20 times the length of the intermediate hollow section.

3. 3. The aerosol-generating article of claim 1, wherein the length of the mouthpiece section is at least 0.30 times the length of the intermediate hollow section.

4. 4. The aerosol-generating article of claim 1, wherein the mouthpiece section comprises a mouthpiece filter segment having a length that is at least 0.10 times and less than 0.34 times the length (L2) of the intermediate hollow section.

5. 5. An aerosol-generating article according to any one of claims 1 to 4, wherein the length of the mouthpiece section is from about 1 mm to about 10 mm, preferably from about 5 mm to about 9 mm, and most preferably about 7 mm.

6. 6. An aerosol-generating article according to any one of claims 1 to 5, wherein the mouthpiece section comprises a mouthpiece filter segment having a length of from about 1 mm to about 10 mm, preferably from about 5 mm to about 9 mm, and most preferably about 7 mm.

7. The resistance to withdrawal (RTD) of the mouthpiece section is about 10 mm H 2 0, most preferably about 7 mm H 2 The aerosol-generating article according to any one of claims 1 to 6.

8. 8. The aerosol-generating article of claim 1, wherein the aerosol-cooling segment comprises a hollow tubular segment defining a longitudinal cavity that provides an unrestricted flow channel, and further comprises a ventilation zone at a location along the hollow tubular segment.

9. 9. The aerosol-generating article of claim 1, wherein the aerosol-generating substrate is a solid aerosol-generating substrate comprising nicotine, one or more cellulosic agents, one or more aerosol formers, and one or more carboxylic acids, the solid aerosol-generating substrate having a total cellulosic agent content of at least 35 percent by weight, a total aerosol former content of at least 45 percent by weight, and a total carboxylic acid content of at least 0.5 percent by weight.

10. 10. The aerosol-generating article of claim 9, wherein the solid aerosol-generating substrate comprises one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, undecanoic acid, and C1 to C10 saturated alkyl monocarboxylic acids.

11. 11. The aerosol-generating article of claim 9 or 10, wherein the solid aerosol-generating substrate comprises fumaric acid.

12. 12. The aerosol-generating article according to claim 9, wherein the solid aerosol-generating substrate further comprises one or more carboxylic acids selected from lactic acid and levulinic acid.

13. 13. The aerosol-generating article of any one of claims 9 to 12, wherein the solid aerosol-generating substrate has a total carboxylic acid content of from 1 weight percent to 6 weight percent.

14. 14. An aerosol-generating article according to any one of claims 9 to 13, wherein the solid aerosol-generating substrate has a total cellulosic agent content of from 35 percent to 50 percent by weight.

15. 15. The aerosol-generating article of any one of claims 9 to 14, wherein the solid aerosol-generating substrate comprises one or more cellulosic film-forming agents selected from carboxymethylcellulose and hydroxypropylmethylcellulose.

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