Aerosol-generating article having a shredded tobacco substrate and an upstream element

Abstract

The aerosol-generating article (10) for producing an inhalable aerosol upon heating comprises: a rod (12) of aerosol-generating substrate having a length of 8 millimeters to 16 millimeters, the aerosol-generating substrate comprising shredded tobacco material having an average density of 150 milligrams per cubic centimeter to 500 milligrams per cubic centimeter; a downstream section (14) located downstream of the rod (12) of aerosol-generating substrate, the downstream section (14) comprising at least one hollow tubular element (20) abutting the downstream end of the rod (12) of aerosol-generating substrate; and an upstream element (42) located upstream of the rod (12) of aerosol-generating substrate and abutting the upstream end of the rod (12) of aerosol-generating substrate, the upstream end of the upstream element (42) defining the upstream end of the aerosol-generating article (10). The ventilation zone (30) is disposed along the hollow tubular element (20), and the distance between the ventilation zone (30) and the upstream end of the upstream element (42) is between 26 millimeters and 33 millimeters.

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. In such heated smoking articles, an aerosol is typically 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. The released compounds condense upon cooling, forming an aerosol.

[0003] Many prior art documents disclose aerosol generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol generating devices in which aerosol is generated by heat transfer from one or more electric heater elements of the aerosol generating device to an aerosol-generating substrate of a 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. The use of an aerosol-generating article in combination with an external heating system is also known. For example, WO 2020 / 115151 describes the provision of one or more heating elements arranged around the periphery of the aerosol-generating article when the aerosol-generating article is received in a cavity of the aerosol-generating device. Alternatively, 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.

[0004] Aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted present many challenges not addressed by conventional smoking articles. First, the tobacco-containing substrate is typically heated to a significantly lower temperature than the temperature reached by the combustion front of a conventional cigarette. This heating can affect nicotine release from the tobacco-containing substrate and nicotine delivery to the consumer. At the same time, if the heating temperature is increased to promote nicotine delivery, the aerosol generated then 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-filtering efficiency segment at the mouth end of the cigarette, can have undesirable effects in aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted, as the solutions can reduce nicotine delivery. Therefore, it would be desirable to provide a new aerosol-generating article that can consistently guarantee satisfactory aerosol delivery to the consumer.

[0005] Second, there is a generally realized need for aerosol-generating articles that are easier to use and have improved utility. For example, it would be desirable to provide an aerosol-generating article that can be easily inserted into the heating cavity of an aerosol generating device and, at the same time, can be securely held within the heating cavity so as not to slip out during use.

[0006] It would therefore be desirable to provide a new and improved aerosol-generating article adapted to achieve at least one of the above-mentioned desired results. It would further be desirable to provide such an aerosol-generating article that can be manufactured efficiently and rapidly, preferably with a satisfactory RTD and low RTD variation between articles. Summary of the Invention

[0007] The present disclosure relates to an aerosol-generating article. The aerosol-generating article may include a rod of an aerosol-generating substrate. The rod of the aerosol-generating article may have a length of at least 8 millimeters. The rod of the aerosol-generating article may have a length of 16 millimeters or less. The aerosol-generating substrate may include shredded tobacco material. The shredded tobacco material may have an average density of at least 150 milligrams per cubic centimeter. The shredded tobacco material may have an average density of 500 milligrams per cubic centimeter or less. The aerosol-generating article may include a hollow tubular element located downstream of the rod of the aerosol-generating substrate. The hollow tubular element may abut the downstream end of the rod of the aerosol-generating substrate. The aerosol-generating article may include an upstream element located upstream of the rod of the aerosol-generating substrate. The upstream element may abut the upstream end of the rod of the aerosol-generating substrate. The upstream end of the upstream element may define the upstream end of the aerosol-generating article. The aerosol-generating article may include a ventilation zone. The ventilation zone may be located at a position along the hollow tubular element, and the distance between the ventilation zone and the upstream end of the upstream element may be between 26 millimeters and 33 millimeters.

[0008] According to the present invention, there is provided an aerosol-generating article comprising a rod of aerosol-generating substrate. The rod of aerosol-generating substrate has a length of 8 millimeters to 16 millimeters, and the aerosol-generating substrate comprises shredded tobacco material having an average density of 150 milligrams per cubic centimeter to 500 milligrams per cubic centimeter. The aerosol-generating article further comprises a hollow tubular element located downstream of the rod of aerosol-generating substrate and abutting the downstream end of the rod of aerosol-generating substrate. The aerosol-generating article further comprises an upstream element located upstream of the rod of aerosol-generating substrate and abutting the upstream end of the rod of aerosol-generating substrate, the upstream end of the upstream element defining the upstream end of the aerosol-generating article. The aerosol-generating article further comprises a ventilation zone located along the hollow tubular element. The distance between the ventilation zone and the upstream end of the upstream element is 26 millimeters to 33 millimeters.

[0009] The aerosol-generating article of the present invention provides an improved configuration that combines a rod of aerosol-generating substrate having a predetermined length with an upstream element immediately upstream of the rod of aerosol-generating substrate, also having a predetermined length, while also defining the density of the tobacco substrate, along with the provision of a ventilation zone along the hollow tubular element immediately downstream of the rod of aerosol-generating article, with the distance between the ventilation zone and the upstream end of the upstream element also being predefined.

[0010] During use, when an aerosol-generating article is received in the heating chamber of an aerosol-generating device, the overall RTD perceived by the consumer is substantially the sum of the overall RTD of the aerosol-generating article and the RTD of the aerosol-generating device. While the RTD of the heating device is generally easy to consistently fine-tune and reproduce so that aerosol-generating devices with the same design have substantially identical RTDs, it is typically more common to observe variations in the RTD of aerosol-generating articles with the same design. This is due to several factors, including the degree of variation inherent in using natural materials (tobacco substrates) in the form of randomly arranged shredded particles within a tobacco rod.

[0011] Typically, the inclusion of a ventilation zone downstream of the rod of the aerosol-generating article tends to complicate this situation because the dilution of the aerosol flow determined by the ingress of ventilation air into the aerosol-generating article is generally greater the higher the RTD upstream of the ventilation zone. Thus, variations in the RTD of the section of the consumable product upstream of the ventilation zone can result in inconsistencies in aerosol delivery and aerosol dilution as well as the overall RTD perceived by the consumer during use.

[0012] The inventors have found that in the aerosol-generating article of the present invention, because a portion of the upstream section of the consumable (i.e., the section of the consumable extending from upstream of the consumable all the way to the ventilation zone) is defined by the upstream element, potential variations in the RTD of the substrate rod have a reduced impact on the total RTD of the upstream section. Furthermore, the length and tobacco density of the substrate rod are selected so that the RTD of the substrate rod can be finely controlled, and in particular, maintained within a predetermined narrow range of values.

[0013] By adjusting the length of the aerosol-generating substrate rod and the density of the shredded tobacco within the aerosol-generating substrate rod within the ranges described above, it is advantageously possible to control the RTD of the aerosol-generating substrate rod to less than 10 mmWG, and in some embodiments, between 6 mmWG and 8 mmWG. Therefore, the effect of variations in the substrate rod RTD on the overall perceived RTD during use is negligible. In fact, the inventors have found that using the aerosol-generating article of the present invention, the overall perceived RTD can be desirably adjusted with good consistency within the range of 80 mmWG to 130 mmWG. These values ​​are consistent with the perceived RTD of conventional cigarettes and have been found to be particularly desirable to consumers.

[0014] By controlling the RTD of the substrate rod low as described above and combining such a rod with a hollow tubular element that contributes little or nothing to the overall RTD of the consumable, the overall RTD of the consumable can be controlled to as little as 20 mmWG or less. This is desirable because the RTD of the heating device can be 60 mmWG or more. This is beneficial in ensuring that the RTD of the aerosol generating device can be at least three times greater than the overall RTD of the consumable. Furthermore, the RTD of the heating device can be substantially greater than the RTD of the substrate rod by an order of magnitude, so that any variation in the RTD of the substrate rod and upstream sections of the consumable is negligible.

[0015] The intense cooling caused by the ingress of ambient air drawn through the ventilation zone into the cavity internally defined by the hollow tubular element is understood to accelerate the condensation of the aerosol former (e.g., glycerol) droplets, where volatile nicotine and organic acids released upon heating of the tobacco substrate accumulate and combine into nicotine salts. With this in mind, the placement of the ventilation zone relative to the upstream end of the upstream element was selected to reduce the flight time of volatile nicotine before it reaches the aerosol former droplets, as well as to create time and space for nicotine accumulation and nicotine salt formation within the aerosol former droplets to occur before the aerosol stream reaches the consumer's mouth.

[0016] Once the substrate shape (volume, length), density, and aerosol former content are selected to provide a particular desired aerosol delivery and RTD to the consumer during use, and the article is designed for use with a particular heating device having predetermined characteristics (e.g., internal or external heating, length and diameter of the heating chamber, etc.), the length of the upstream element can be adjusted within each claimed range so that the positioning of the ventilation zone relative to the upstream end of the upstream element is also within each claimed range.

[0017] Thus, in articles of the present invention, the selected length of the upstream element and the distance between the ventilation zone and the upstream end of the upstream element provide a combination that optimizes the placement of the substrate and the placement of the ventilation zone within the aerosol generating device to improve aerosol generation and delivery to the consumer.

[0018] In a preferred embodiment, the distance between the ventilation zone and the upstream end of the upstream element is between 27 mm and 31 mm.

[0019] In the aerosol-generating article according to the present invention, the rod of the aerosol-generating substrate preferably has a length of 8 mm to 16 mm, more preferably 10 mm to 14 mm.

[0020] The aerosol-generating article according to the present invention comprises a rod of aerosol-generating substrate. The aerosol-generating article according to the present invention further comprises one or more elements arranged downstream of the aerosol-generating substrate. The one or more elements downstream of the rod of the aerosol-generating article form a downstream section of the aerosol-generating substrate. The aerosol-generating article according to the present invention further comprises an element arranged upstream of the aerosol-generating substrate. The element upstream of the rod of the aerosol-generating substrate defines an upstream section of the aerosol-generating article.

[0021] The rod of aerosol-generating substrate is preferably surrounded by a wrapper such as plug wrap.

[0022] Preferably, the aerosol-generating substrate rod has a length of at least about 8 millimeters. Preferably, the aerosol-generating substrate rod has a length of at least about 9 millimeters. More preferably, the aerosol-generating substrate rod has a length of at least about 10 millimeters.

[0023] For example, the aerosol-generating substrate rod preferably has a length of about 8 mm to about 16 mm, or about 9 mm to about 15 mm, or about 10 mm to about 14 mm. In a particularly preferred embodiment, the aerosol-generating substrate rod has a length of about 12 mm.

[0024] Preferably, the ratio of the length of the rod of the aerosol-generating substrate to the overall length of the aerosol-generating article is at least about 0.15, more preferably at least about 0.2, and most preferably at least about 0.22.

[0025] Preferably, the ratio of the length of the rod of the aerosol-generating substrate to the overall length of the aerosol-generating article is 0.35 or less, more preferably about 0.33 or less, more preferably about 0.3 or less.

[0026] In a particularly preferred embodiment of the invention, the ratio of the length of the rod of the aerosol-generating substrate to the overall length of the aerosol-generating article is about 0.25.

[0027] The rod of the aerosol-generating substrate preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article.

[0028] The "outer diameter of the aerosol-generating substrate rod" may be calculated as the average of multiple measurements of the diameter of the aerosol-generating substrate rod taken at different positions along the length of the aerosol-generating substrate rod.

[0029] Preferably, the aerosol-generating substrate rod has an outer diameter of at least about 5 millimeters. More preferably, the aerosol-generating substrate rod has an outer diameter of at least about 6 millimeters. Even more preferably, the aerosol-generating substrate rod has an outer diameter of at least about 7 millimeters.

[0030] Preferably, the aerosol-generating substrate rod has an outer diameter of about 12 millimeters or less. More preferably, the aerosol-generating substrate rod has an outer diameter of about 10 millimeters or less. Even more preferably, the aerosol-generating substrate rod has an outer diameter of about 8 millimeters or less.

[0031] It has generally been observed that the smaller the diameter of the aerosol-generating substrate rod, the lower the temperature required to raise the core temperature of the aerosol-generating substrate rod so that a sufficient amount of volatile species is released from the aerosol-generating substrate to form the desired amount of aerosol. At the same time, without intending to be bound by theory, it is understood that the smaller the diameter of the aerosol-generating substrate rod, the more quickly the heat supplied to the aerosol-generating article can penetrate the entire volume of the aerosol-forming substrate. Nevertheless, if the diameter of the aerosol-generating substrate rod is too small, the volume-to-surface area ratio of the aerosol-generating substrate becomes unfavorable as the amount of available aerosol-forming substrate decreases.

[0032] Aerosol-generating substrate rod diameters within the ranges described herein are particularly advantageous in terms of the balance between energy consumption and aerosol delivery. This advantage is particularly realized when an aerosol-generating article including an aerosol-generating substrate rod having the diameters described herein is used in combination with an external heater positioned around the periphery of the aerosol-generating article. Under such operating conditions, it has been observed that less thermal energy is required to achieve a sufficiently high temperature at the core of the aerosol-generating substrate rod, typically at the core of the article. Thus, when operating at lower temperatures, the desired target temperature at the core of the aerosol-generating substrate can be achieved within a desirably reduced time frame and with less energy consumption.

[0033] In some embodiments, the aerosol-generating substrate rod 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 substrate rod has an outer diameter of about 5 mm to about 12 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 substrate rod 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.

[0034] In a particularly preferred embodiment, the rod of aerosol-generating substrate has an outer diameter of less than about 7.5 millimeters. By way of example, the rod of aerosol-generating substrate may have an outer diameter of about 7.2 millimeters.

[0035] The ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article may be at least about 0.10. Preferably, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article is at least about 0.15. More preferably, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article is at least about 0.20. Even more preferably, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article is at least about 0.25.

[0036] Generally, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article may be about 0.60 or less. Preferably, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article is about 0.50 or less. More preferably, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article is about 0.45 or less. Even more preferably, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article is about 0.40 or less. In a particularly preferred embodiment, the ratio between the length of the aerosol-generating substrate rod and the total length of the aerosol-generating article is about 0.35 or less, and most preferably about 0.30 or less.

[0037] In some embodiments, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article is about 0.10 to about 0.45, preferably about 0.15 to about 0.45, more preferably about 0.20 to about 0.45, and even more preferably about 0.25 to about 0.45. In other embodiments, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article is about 0.10 to about 0.40, preferably about 0.15 to about 0.40, more preferably about 0.20 to about 0.40, and even more preferably about 0.25 to about 0.40. In further embodiments, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article is about 0.10 to about 0.35, preferably about 0.15 to about 0.35, more preferably about 0.20 to about 0.35, and even more preferably about 0.25 to about 0.35. In yet a further embodiment, the ratio between the length of the rod of the aerosol-generating substrate and the overall length of the aerosol-generating article is from about 0.10 to about 0.30, preferably from about 0.15 to about 0.30, more preferably from about 0.20 to about 0.30, and even more preferably from about 0.25 to about 0.30.

[0038] Preferably, the rod of aerosol-generating substrate has a substantially uniform cross section along the length of the rod, and it is particularly preferred that the rod of aerosol-generating substrate has a substantially circular cross section.

[0039] In the aerosol-generating article according to the present invention, the ratio between the length of the rod of the aerosol-generating substrate and the overall length of the aerosol-generating article may be about 0.60 or less. Preferably, the ratio between the length of the rod of the aerosol-generating substrate and the overall length of the aerosol-generating article may be about 0.50 or less. More preferably, the ratio between the length of the rod of the aerosol-generating substrate and the overall length of the aerosol-generating article may be about 0.40 or less. Even more preferably, the ratio between the length of the rod of the aerosol-generating substrate and the overall length of the aerosol-generating article may be about 0.30 or less.

[0040] In the aerosol-generating article according to the present invention, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article may be at least about 0.10. Preferably, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article may be at least about 0.15. More preferably, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article may be at least about 0.20. In a particularly preferred embodiment, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article may be at least about 0.25.

[0041] In some embodiments, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article is about 0.10 to about 0.60, preferably about 0.15 to about 0.60, more preferably about 0.20 to about 0.60, and even more preferably about 0.25 to about 0.60. In other embodiments, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article is about 0.10 to about 0.50, preferably about 0.15 to about 0.50, more preferably about 0.20 to about 0.50, and even more preferably about 0.25 to about 0.50. In further embodiments, the ratio between the length of the rod of the aerosol-generating substrate and the total length of the aerosol-generating article is about 0.10 to about 0.40, preferably about 0.15 to about 0.40, more preferably about 0.20 to about 0.40, and even more preferably about 0.25 to about 0.40. As an example, the ratio between the length of the rod of the aerosol-generating substrate and the overall length of the aerosol-generating article may be from about 0.25 to about 0.30, preferably about 0.27.

[0042] Preferably, the density of the aerosol-generating substrate is at least about 150 milligrams per cubic centimeter. More preferably, the density of the aerosol-generating substrate is at least about 175 milligrams per cubic centimeter. More preferably, the density of the aerosol-generating substrate is at least about 200 milligrams per cubic centimeter. Even more preferably, the density of the aerosol-generating substrate is at least about 250 milligrams per cubic centimeter.

[0043] Preferably, the density of the aerosol-generating substrate is about 500 milligrams per cubic centimeter or less. More preferably, the density of the aerosol-generating substrate is at least about 450 milligrams per cubic centimeter. More preferably, the density of the aerosol-generating substrate is about 400 milligrams per cubic centimeter or less. Even more preferably, the density of the aerosol-generating substrate is about 350 milligrams per cubic centimeter or less.

[0044] For example, the density of the aerosol-generating substrate may be from about 150 milligrams per cubic centimeter to about 500 milligrams per cubic centimeter, preferably from about 175 milligrams per cubic centimeter to about 450 milligrams per cubic centimeter, more preferably from about 200 milligrams per cubic centimeter to about 400 milligrams per cubic centimeter, and even more preferably from 250 milligrams per cubic centimeter to 350 milligrams per cubic centimeter. In a particularly preferred embodiment, the density of the aerosol-generating substrate is about 300 milligrams per cubic centimeter.

[0045] In certain preferred embodiments, the rod of aerosol-generating substrate comprises shredded tobacco material, e.g., a tobacco cut filler having a density of from about 150 milligrams per cubic centimeter to about 500 milligrams per cubic centimeter, preferably from about 175 milligrams per cubic centimeter to about 450 milligrams per cubic centimeter, more preferably from about 200 milligrams per cubic centimeter to about 400 milligrams per cubic centimeter, more preferably from about 250 milligrams per cubic centimeter to about 350 milligrams per cubic centimeter, and most preferably about 300 milligrams per cubic centimeter.

[0046] Preferably, the RTD of the aerosol-generating substrate rod is about 10 millimeters HO or less. More preferably, the RTD of the aerosol-generating substrate rod is about 9 millimeters HO or less. Even more preferably, the RTD of the aerosol-generating substrate rod is about 8 millimeters HO or less.

[0047] Preferably, the RTD of the aerosol-generating substrate rod is at least about 4 millimeters HO. More preferably, the RTD of the aerosol-generating substrate rod is at least about 5 millimeters HO. Even more preferably, the RTD of the aerosol-generating substrate rod is at least about 6 millimeters HO.

[0048] In some embodiments, the RTD of the aerosol-generating substrate rod is from about 4 millimeters HO to about 10 millimeters HO, preferably from about 5 millimeters HO to about 10 millimeters HO, and more preferably from about 6 millimeters HO to about 25 millimeters HO. In other embodiments, the RTD of the aerosol-generating substrate rod is from about 4 millimeters HO to about 20 millimeters HO, preferably from about 5 millimeters HO to about 18 millimeters HO, and more preferably from about 6 millimeters HO to about 16 millimeters HO. In further embodiments, the RTD of the aerosol-generating substrate rod is from about 4 millimeters HO to about 15 millimeters HO, preferably from about 5 millimeters HO to about 14 millimeters HO, and more preferably from about 6 millimeters HO to about 12 millimeters HO.

[0049] The aerosol-generating substrate may be a solid aerosol-generating substrate. Preferably, the aerosol-generating substrate comprises an aerosol former. The aerosol former may be any suitable, well-known compound or mixture of compounds that promotes the formation of a dense, stable aerosol during use. The aerosol former may promote the aerosol to be substantially resistant to thermal decomposition at temperatures typically encountered during use of the aerosol-generating article. Suitable aerosol formers include, for example, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, propylene glycol, and glycerin), esters of polyhydric alcohols (e.g., glycerol monoacetate, diacetate, or triacetate), aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (e.g., dimethyl dodecanedioate and dimethyl tetradecanedioate), and combinations thereof.

[0050] The aerosol former preferably comprises one or more of glycerin and propylene glycol. The aerosol former may consist of glycerin or propylene glycol, or a combination of glycerin and propylene glycol.

[0051] Preferably, the aerosol-generating substrate comprises at least 5 weight percent aerosol formers, based on the dry weight of the aerosol-generating substrate, more preferably 10 to 22 weight percent, based on the dry weight of the cut aerosol-generating substrate, more preferably the amount of aerosol formers is 12 to 19 weight percent, based on the dry weight of the aerosol-generating substrate, and most preferably, for example, the amount of aerosol formers is 13 to 16 weight percent, based on the dry weight of the aerosol-generating substrate.

[0052] In certain preferred embodiments of the present invention, the aerosol-generating substrate comprises shredded tobacco material. For example, the shredded tobacco material may be in the form of cut filler, as described in more detail below. Alternatively, the shredded tobacco material may be in the form of shredded sheets of homogenized tobacco material. Suitable homogenized tobacco materials for use in the present invention are described below.

[0053] In the context of this specification, the term "cut filler" is used to describe a blend of shredded plant material, such as tobacco plant material, including, inter alia, one or more of leaf laminae, processed stems and ribs, and homogenized plant material.

[0054] The cut filler may also include other pre-cut filler tobaccos or casings.

[0055] Preferably, the cut filler comprises at least 25 percent plant leaf lamina, more preferably at least 50 percent plant leaf lamina, even more preferably at least 75 percent plant leaf lamina, and most preferably at least 90 percent plant leaf lamina. Preferably, the plant material is one of tobacco, mint, tea, and cloves. Most preferably, the plant material is tobacco. However, the present invention is equally applicable to other plant materials capable of releasing, upon heating, a substance capable of subsequently forming an aerosol, as described in more detail below.

[0056] Preferably, the chopped filler comprises tobacco plant material including one or more lamina of bright tobacco, dark tobacco, aromatic tobacco, and filler tobacco. In the context of the present invention, the term "tobacco" refers to any plant member of the Nicotiana species.

[0057] Bright tobacco is generally a tobacco with large, light-colored leaves. Throughout this specification, the term "bright tobacco" refers to fully cured (flue-cured) tobacco. Examples of bright tobacco include fully cured Chinese tobacco, fully cured Brazilian tobacco, fully cured American tobacco (such as Virginia tobacco), fully cured Indian tobacco, fully cured Tanzanian tobacco, or fully cured African tobacco. Bright tobacco is characterized by a high sugar-to-nitrogen ratio. From a sensory perspective, bright tobacco is a type of tobacco that has a flavorful and lively sensation after curing. According to the present invention, bright tobacco is tobacco that has a reducing sugar content of about 2.5 percent to about 20 percent, based on dry weight of the leaf, and a total ammonia content of less than about 0.12 percent, based on dry weight of the leaf. Reducing sugars include, for example, glucose or fructose. Total ammonia includes, for example, ammonia and ammonia salts.

[0058] Dark tobacco is generally tobacco with large, dark-colored leaves. Throughout this specification, the term "dark tobacco" refers to air-cured tobacco. Additionally, dark tobacco may be fermented. Tobacco primarily used for chewing tobacco, snuff, cigar tobacco, and pipe blends also fall into this category. Typically, these dark tobaccos are air-cured and, if possible, fermented. From a sensory perspective, dark tobacco is a type of tobacco that produces smoke and a dark cigar-type sensation after curing. Dark tobacco is characterized by a low sugar-to-nitrogen ratio. Examples of dark tobacco are Malawi or other African burley, dark-cured Brazil galpao, san-cured, or air-cured Indonesian kasturi. According to the present invention, dark tobacco is tobacco with a reducing sugar content of less than about 5 percent, based on dry weight of the leaf, and a total ammonia content of about 0.5 percent or less, based on dry weight of the leaf.

[0059] Aromatic tobaccos are tobaccos that often have small, light-colored leaves. Throughout this specification, the term "aromatic tobacco" is used in contrast to other tobaccos with high aromatic content, e.g., essential oil content. From a sensory perspective, aromatic tobaccos are tobaccos that have a fragrant flavor and a fragrant sensation after curing. Examples of aromatic tobaccos include Greek Orient, Orient Turkey, semi-oriental tobaccos that have been flue-cured, US Burley such as Perique, Rustica, US Burley, or Maryland. Filler tobacco is not a specific type of tobacco, but includes tobaccos that are primarily used to complement other tobacco types used in blends and do not contribute a specific characteristic aroma direction to the final product. Examples of filler tobaccos are the stems, midribs, or petioles of other types of tobacco. A specific example would be the flue-cured stems of the lower petioles of flue-cured Brazilian tobacco.

[0060] The cut filler suitable for use in the present invention may generally be similar to the cut filler used in conventional smoking articles. The cut width of the cut filler is preferably 0.3 mm to 2.0 mm, more preferably 0.5 mm to 1.2 mm, and most preferably 0.6 mm to 0.9 mm. The cut width may play a role in the distribution of heat within the rod of the aerosol-generating substrate. The cut width may also play a role in the draw resistance of the article. Furthermore, the cut width may affect the overall density of the entire aerosol-generating substrate.

[0061] The strand length of the cut filler is somewhat random, since it depends on the overall size of the object from which the strands are cut. Nevertheless, longer strands can be cut by conditioning the material before cutting, for example, by controlling the moisture content and overall fineness of the material. Preferably, the strands have a length of about 10 millimeters to about 40 millimeters before aligning them to form the aerosol-generating substrate rod. Obviously, if the strands are arranged in the aerosol-generating substrate rod at a longitudinal extension of the section that is less than 40 millimeters, the final aerosol-generating substrate rod may contain strands that are, on average, shorter than the initial strand length. Preferably, the strand length of the cut filler is such that about 20 percent to 60 percent of the strands extend along the entire length of the aerosol-generating substrate rod. This prevents the strands from easily detaching from the aerosol-generating substrate rod.

[0062] In a preferred embodiment, the weight of the cut filler is between 80 milligrams and 400 milligrams, preferably between 150 milligrams and 250 milligrams, and more preferably between 170 milligrams and 220 milligrams. This amount of cut filler can provide sufficient material for forming an aerosol. Additionally, given the aforementioned constraints on diameter and size, this allows for a balance of the density of the rod of aerosol-generating substrate between energy uptake, resistance to drawing, and fluid passage of the rod of aerosol-generating substrate containing plant material.

[0063] Preferably, the cut filler is immersed in the aerosol former. Immersion of the cut filler can be achieved by spraying or other suitable application methods. The aerosol former can be applied to the blend during preparation of the cut filler. For example, the aerosol former can be applied to the blend in a direct conditioning casing cylinder (DCCC). Conventional machinery can be used to apply the aerosol former to the cut filler. The aerosol former can be any suitable known compound or mixture of compounds that promotes the formation of a dense, stable aerosol upon use. The aerosol former can promote the aerosol to be substantially resistant to thermal decomposition at temperatures typically encountered during use of the aerosol-generating article. Suitable aerosol formers are, for example, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, propylene glycol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate), and combinations thereof.

[0064] The aerosol former preferably comprises one or more of glycerin and propylene glycol. The aerosol former may consist of glycerin or propylene glycol, or a combination of glycerin and propylene glycol.

[0065] Preferably, the amount of aerosol former is at least 5 weight percent based on the dry weight of the cut filler, preferably 10 to 22 weight percent based on the dry weight of the cut filler, and more preferably 12 to 19 weight percent based on the dry weight of the cut filler, for example, 13 to 16 weight percent based on the dry weight of the cut filler. When the aerosol former is added to the cut filler in the amounts described above, the cut filler can become relatively sticky. This advantageously helps to hold the cut filler in place within the article, as the cut filler particles tend to adhere to surrounding cut filler particles as well as surrounding surfaces (e.g., the inner surface of the wrapper surrounding the cut filler).

[0066] In some embodiments, the amount of aerosol former has a target value of about 13 weight percent, based on the dry weight of the cut filler. The most effective amount of aerosol former also depends on the cut filler and whether the cut filler contains plant lamina or homogenized plant material. For example, the type of cut filler, among other factors, determines the extent to which the aerosol former can promote the release of material from the cut filler.

[0067] For these reasons, the aerosol-generating substrate rods containing the cut filler described above can efficiently generate sufficient aerosol at relatively low temperatures. Temperatures of 150°C to 200°C in a heating chamber are sufficient for a single such cut filler to generate a sufficient amount of aerosol, while aerosol-generating devices using cast tobacco leaf sheets typically use temperatures of about 250°C.

[0068] A further advantage of the present invention related to operation at lower temperatures is that the need for aerosol cooling is reduced. Generally, due to the use of lower temperatures, simpler cooling mechanisms may be sufficient. This, in turn, allows for simpler, less complex construction of the aerosol-generating article.

[0069] In another preferred embodiment, the aerosol-generating substrate comprises homogenized plant material, preferably homogenized tobacco material.

[0070] 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, milling, 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.

[0071] The homogenized plant material may be provided in any suitable form.

[0072] In some embodiments, the homogenized plant material may be in the form of one or more sheets. As used herein with respect to the present invention, the term "sheet" refers to a laminar element having a width and length that is substantially greater than its thickness.

[0073] The homogenized plant material may be in the form of multiple pellets or granules.

[0074] The homogenized plant material may be in the form of multiple strands, pieces, or fragments. As used herein, the term "strand" refers to 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 chopping, or by other methods, such as extrusion methods.

[0075] 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.

[0076] When the homogenized plant material is in the form of one or more sheets, the sheets may be produced by a molding process, as described above. Alternatively, the sheets of homogenized plant material may be produced by a papermaking process.

[0077] 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. While individual thickness refers to the thickness of an individual sheet, 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.

[0078] One or more of the sheets described herein can each individually have a basis weight of from about 100 grams per square meter to about 600 grams per square meter.

[0079] One or more sheets as described herein may each individually have a density of from about 0.3 grams per cubic centimeter to about 1.3 grams per cubic centimeter, preferably from about 0.7 grams per cubic centimeter to about 1.0 grams per cubic centimeter.

[0080] 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" means that the sheets of homogenized plant material are coiled, folded, or otherwise compressed or contracted in a direction substantially transverse to the cylindrical axis of the plug or rod.

[0081] 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.

[0082] One or more sheets of homogenized plant material may advantageously be crimped or similarly treated. As used herein, the term "crimped" refers to a sheet having a plurality of substantially parallel ridges or corrugations. One or more sheets of homogenized plant material may be embossed, debossed, perforated, or otherwise deformed to provide a texture on one or both sides of the sheet.

[0083] Preferably, each sheet of homogenized plant material can 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 the plug. Preferably, more than one sheet of homogenized plant material can be assembled. Of course, the crimped sheet of homogenized plant material can alternatively or additionally have a plurality of substantially parallel ridges or corrugations disposed at acute or obtuse angles relative to the cylindrical axis of the plug. The sheet can be crimped to an extent that the integrity of the sheet is interrupted 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.

[0084] Alternatively, one or more sheets of homogenized plant material can be cut into strands, as mentioned above. In such embodiments, the aerosol-generating substrate includes a plurality of 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, about 2 millimeters, or less. The length of the strands can be greater than about 5 millimeters, about 5 millimeters to about 15 millimeters, about 8 millimeters to about 12 millimeters, or about 12 millimeters. Preferably, the strands have substantially the same length as one another.

[0085] 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.

[0086] 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.

[0087] In certain embodiments of the present invention, the homogenized plant material is a homogenized tobacco material comprising tobacco particles. Sheets of homogenized tobacco material for use 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, even 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.

[0088] For purposes of the present invention, the term "tobacco particles" refers to particles of any plant material of the Nicotiana species. The term "tobacco particles" encompasses ground or powdered tobacco lamina, ground or powdered tobacco stems, tobacco dust, tobacco fines, and other particulate tobacco by-products formed during tobacco processing, handling, and shipping. In 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.

[0089] The homogenized plant material may further include one or more aerosol formers, which, upon volatilization, can carry other vaporized compounds released from the aerosol-generating substrate upon heating, such as nicotine and flavorants in the aerosol. Suitable aerosol formers for inclusion in the homogenized plant material are well known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, propylene glycol, 1,3-butanediol, and glycerol), esters of polyhydric alcohols (such as glycerol mono-, di-, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and tetradecanedioate).

[0090] The homogenized plant material may have an aerosol former content of about 5 to about 30 percent by weight on a dry weight basis, such as about 10 to about 25 percent by weight on a dry weight basis, or about 15 to about 20 percent by weight on a dry weight basis. The aerosol former may act as a humectant in the homogenized plant material.

[0091] As mentioned above, the rod of aerosol-generating substrate may be surrounded by a wrapper. The wrapper surrounding the rod of aerosol-generating substrate may be a paper wrapper or a non-paper wrapper. Suitable paper wrappers for use in certain embodiments of the present invention are well 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 well known in the art and include, but are not limited to, sheets of homogenized tobacco material.

[0092] The paper wrapper may have a basis weight of at least 15 gsm, preferably at least 20 gsm. The paper wrapper may be 35 gsm or less, preferably 30 gsm or less. The paper wrapper may have a basis weight of 15 gsm to 35 gsm, preferably 20 gsm to 30 gsm. In a preferred embodiment, the paper wrapper may have a basis weight of 25 gsm. The paper wrapper may have a thickness of at least 25 micrometers, preferably at least 30 micrometers, and more preferably at least 35 micrometers. The paper wrapper may have a thickness of 55 micrometers or less, preferably 50 micrometers or less, and more preferably 45 micrometers or less. The paper wrapper may have a thickness of 25 micrometers to 55 micrometers, preferably 30 micrometers to 50 micrometers, and more preferably 35 micrometers to 45 micrometers. In a preferred embodiment, the paper wrapper may have a thickness of 40 micrometers.

[0093] 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 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.

[0094] The paper layer of the co-laminate sheet may have a basis weight of at least 35 gsm, preferably at least 40 gsm. The paper layer of the co-laminate sheet may have a basis weight of 55 gsm or less, preferably 50 gsm or less. The paper layer of the co-laminate sheet may have a basis weight of 35 gsm to 55 gsm, preferably 40 gsm to 50 gsm. In a preferred embodiment, the paper layer of the co-laminate sheet may have a basis weight of 45 gsm.

[0095] The paper layer of the co-laminate sheet may have a thickness of at least 50 micrometers, preferably at least 55 micrometers, more preferably at least 60 micrometers. The paper layer of the co-laminate sheet may have a thickness of 80 micrometers or less, preferably 75 micrometers or less, more preferably 70 micrometers or less.

[0096] The paper layer of the co-laminate sheet may have a thickness of 50 micrometers to 80 micrometers, preferably 55 micrometers to 75 micrometers, and more preferably 60 micrometers to 70 micrometers. In a preferred embodiment, the paper layer of the co-laminate sheet may have a thickness of 65 micrometers.

[0097] The metal layer of the co-laminate sheet may have a basis weight of at least 12 gsm, preferably at least 15 gsm. The metal layer of the co-laminate sheet may have a basis weight of 25 gsm or less, preferably 20 gsm or less. The metal layer of the co-laminate sheet may have a basis weight of 12 gsm to 25 gsm, preferably 15 gsm to 20 gsm. In a preferred embodiment, the metal layer of the co-laminate sheet may have a basis weight of 17 gsm.

[0098] The metal layer of the co-laminate sheet may have a thickness of at least 2 micrometers, preferably at least 3 micrometers, more preferably at least 5 micrometers. The metal layer of the co-laminate sheet may have a thickness of 15 micrometers or less, preferably 12 micrometers or less, more preferably 10 micrometers or less.

[0099] The metal layer of the co-laminate sheet may have a thickness of 2 micrometers to 15 micrometers, preferably 3 micrometers to 12 micrometers, and more preferably 5 micrometers to 10 micrometers. In a preferred embodiment, the metal layer of the co-laminate sheet may have a thickness of 6 micrometers.

[0100] The wrapper surrounding the rod of aerosol-generating substrate may be a paper wrapper containing PVOH (polyvinyl alcohol) or silicone. The addition of PVOH (polyvinyl alcohol) or silicone may improve the grease barrier properties of the wrapper.

[0101] The PVOH or silicone may be applied to the paper layer as a surface coating, such as being disposed on the outer surface of the paper layer of the wrapper surrounding the rod of the aerosol-generating substrate. The PVOH or silicone may be disposed on the outer surface of the paper layer of the wrapper and form a layer. The PVOH or silicone may be disposed on the inner surface of the paper layer of the wrapper. The PVOH or silicone may be disposed on the inner surface of the paper layer of the aerosol-generating article and form a layer. The PVOH or silicone may be disposed on both the inner and outer surfaces of the paper layer of the wrapper. The PVOH or silicone may be disposed on the inner and outer surfaces of the paper layer of the wrapper and form a layer.

[0102] The PVOH or silicone-containing paper wrapper may have a basis weight of at least 20 gsm, preferably at least 25 gsm, and more preferably at least 30 gsm. The PVOH or silicone-containing paper wrapper may have a basis weight of 50 gsm or less, preferably 45 gsm or less, and more preferably 40 gsm or less. The PVOH or silicone-containing paper wrapper may have a basis weight of 20 gsm to 50 gsm, preferably 25 gsm to 45 gsm, and more preferably 30 gsm to 40 gsm. In a particularly preferred embodiment, the PVOH or silicone-containing paper wrapper may have a basis weight of about 35 gsm.

[0103] The PVOH or silicone-containing paper wrapper may have a thickness of at least 25 micrometers, preferably at least 30 micrometers, and more preferably at least 35 micrometers. The PVOH or silicone-containing paper wrapper may have a thickness of 50 micrometers or less, preferably 45 micrometers or less, and more preferably 40 micrometers or less. The PVOH or silicone-containing paper wrapper may have a thickness of 25 micrometers to 50 micrometers, preferably 30 micrometers to 45 micrometers, and more preferably 35 micrometers to 40 micrometers. In a particularly preferred embodiment, the PVOH or silicone-containing paper wrapper may have a thickness of 37 micrometers.

[0104] The wrapper surrounding the rod of aerosol-generating substrate may include a flame-retardant composition comprising one or more flame-retardant compounds. The term "flame-retardant compound" is used herein to refer to a compound that, when added to or otherwise incorporated into a carrier substrate, such as a paper or plastic compound, provides varying degrees of flammability protection to the carrier substrate. In practice, the flame-retardant compound may be activated by the presence of an ignition source and may be adapted to prevent or delay further ignition by a variety of different physical and chemical mechanisms.

[0105] Flame-retardant compositions typically may further include one or more non-flame-retardant compounds, i.e., one or more compounds, such as solvents, excipients, fillers, etc., that do not actively contribute to providing flammability protection to the carrier substrate but are used to facilitate application of the flame-retardant compound onto or into the wrapper, or both. Some of the non-flame-retardant compounds of the flame-retardant composition, such as solvents, are volatile and can evaporate from the wrapper upon drying after the flame-retardant composition is applied onto or into the wrapping substrate, or both. Thus, while such non-flame-retardant compounds form part of the formulation of the flame-retardant composition, they may no longer be present, or may be detectable only in trace amounts, in the wrapper of the aerosol-generating article.

[0106] Many suitable flame retardant compounds will be known to those skilled in the art, and several flame retardant compounds and formulations, particularly those suitable for treating cellulosic materials, are known and disclosed and may find use in the manufacture of wrappers for aerosol-generating articles according to the present invention.

[0107] For example, the flame retardant composition may comprise a polymer and a mixed salt based on at least one monocarboxylic acid, dicarboxylic acid and / or tricarboxylic acid, at least one polyphosphoric acid, pyrophosphoric acid and / or phosphoric acid, and a hydroxide or salt of an alkali or alkaline earth metal, where the at least one monocarboxylic acid, dicarboxylic acid and / or tricarboxylic acid and the hydroxide or salt form a carboxylate salt, and at least one polyphosphoric acid, and the pyrophosphoric acid and / or phosphoric acid and the hydroxide or salt form a phosphate salt. Preferably, the flame retardant composition further comprises a carbonate salt of an alkali or alkaline earth metal. Alternatively, the flame retardant composition may comprise at least one C 10 The cellulose may be modified with the above fatty acids, tall oil fatty acid (TOFA), phosphorylated linseed oil, or phosphorylated lower corn oil. Preferably, the cellulose may be modified with at least one C 10 The fatty acids are selected from the group consisting of capric acid, myristic acid, palmitic acid, and combinations thereof.

[0108] In wrappers containing a flame-retardant composition suitable for use in aerosol-generating articles according to the present invention, the flame-retardant composition can be provided in a treated portion of the wrapper. This means that the flame-retardant composition is applied to or within a corresponding portion of the wrapping substrate, or both. Thus, in the treated portion, the wrapper has a total dry weight greater than the dry basis weight of the wrapping substrate. The treated portion of the wrapper can extend over at least about 10 percent of the outer surface area of ​​the rod of aerosol-generating substrates surrounded by the wrapper, preferably over at least about 20 percent of the outer surface area of ​​the rod of aerosol-generating substrates surrounded by the wrapper, more preferably over at least about 40 percent of the outer surface area of ​​the rod of aerosol-generating substrates, and even more preferably over at least about 60 percent of the outer surface area of ​​the rod of aerosol-generating substrates. Most preferably, the treated portion of the wrapper extends over at least about 80 percent of the outer surface area of ​​the rod of aerosol-generating substrates. In particularly preferred embodiments, the treated portion of the wrapper extends over at least about 90 or even 95 percent of the outer surface area of ​​the rod of aerosol-generating substrates. Most preferably, the treated portion of the wrapper extends over substantially the entire outer surface area of ​​the rod of the aerosol-generating substrate.

[0109] The wrapper containing the flame retardant composition may have a basis weight of at least 20 gsm, preferably at least 25 gsm, and more preferably at least 30 gsm. The wrapper containing the flame retardant composition may have a basis weight of 45 gsm or less, preferably 40 gsm or less, and more preferably 35 gsm or less. The wrapper containing the flame retardant composition may have a basis weight of 20 gsm to 45 gsm, preferably 25 gsm to 40 gsm, and more preferably 30 gsm to 35 gsm. In some preferred embodiments, the wrapper containing the flame retardant composition may have a basis weight of 33 gsm.

[0110] The wrapper containing the flame retardant composition may have a thickness of at least 25 micrometers, preferably at least 30 micrometers, and even more preferably 35 micrometers. The wrapper containing the flame retardant composition may have a thickness of 50 micrometers or less, preferably 45 micrometers or less, and even more preferably 40 micrometers or less. In some embodiments, the wrapper containing the flame retardant composition may have a thickness of 37 micrometers.

[0111] The aerosol-generating article according to the present disclosure comprises an upstream section located upstream of the rod of aerosol-generating substrate. The upstream section is preferably located immediately upstream of the rod of aerosol-generating substrate. The upstream section preferably extends between the upstream end of the aerosol-generating article and the rod of aerosol-generating substrate. The upstream section may comprise one or more upstream elements located upstream of the rod of aerosol-generating substrate. Such one or more upstream elements are described in the present disclosure.

[0112] The aerosol-generating article of the present invention preferably comprises an upstream element located upstream of and adjacent to the aerosol-generating substrate. The upstream element advantageously prevents direct physical contact with the upstream end of the aerosol-generating substrate. For example, if the aerosol-generating substrate comprises a susceptor element, the upstream element 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 element helps to prevent any loss of the substrate, which may be advantageous, for example, when the substrate contains particulate plant material.

[0113] Where the aerosol-generating substrate comprises shredded tobacco, such as tobacco cut filler, the upstream section or element thereof may further help to prevent the loss of loose particles of tobacco from the upstream end of the article.

[0114] The upstream section, or upstream element thereof, may also cover at least some of the upstream end of the aerosol-generating substrate and therefore provide an additional degree of protection to the aerosol-generating substrate during storage, which may otherwise be exposed.

[0115] For aerosol-generating articles intended to be inserted into a cavity in an aerosol-generating device so that the aerosol-generating substrate can be heated externally within the cavity, the upstream section, or upstream element thereof, may advantageously facilitate insertion of the upstream end of the article into the cavity. The inclusion of an upstream element may further protect the rod end of the aerosol-generating substrate during insertion of the article into the cavity so as to minimize the risk of damage to the substrate.

[0116] The upstream section, or upstream elements thereof, may also provide an improved appearance to the upstream end of the aerosol-generating article. Furthermore, if desired, the upstream section, or upstream elements thereof, may 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 with which the aerosol-generating article is intended to be used.

[0117] The upstream element may be a porous plug element. Preferably, the upstream element has a porosity of at least about 50 percent along the longitudinal axis of the aerosol-generating article. More preferably, the upstream element has a porosity of between about 50 percent and about 90 percent along the longitudinal axis. The porosity of the upstream element along the longitudinal axis is defined as the ratio of the cross-sectional area of ​​the material forming the upstream element to the internal cross-sectional area of ​​the aerosol-generating article at the location of the upstream element.

[0118] The upstream element may be made of a porous material or may include a plurality of openings, which may be achieved, for example, by laser drilling. The plurality of openings is preferably uniformly distributed across the cross section of the upstream element.

[0119] The porosity or permeability of the upstream element can advantageously be designed to provide a particular overall resistance to draw (RTD) for the aerosol-generating article without substantially affecting the filtration provided by other parts of the article.

[0120] The upstream element 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 via suitable venting means provided in the wrapper.

[0121] In certain preferred embodiments of the present invention, it may be desirable to minimize the RTD of the upstream element. For example, this may be the case for an article intended to be inserted into the cavity of an aerosol-generating device, such that the aerosol-generating substrate is heated externally, as described herein. For such articles, it is desirable to provide the article with the lowest possible RTD, so that the majority of the consumer's RTD experience is provided by the aerosol-generating device, rather than the article.

[0122] The RTD of the upstream element is preferably about 10 millimeters of H2O or less. More preferably, the RTD of the upstream element is about 5 millimeters of H2O or less. Even more preferably, the RTD of the upstream element is about 2.5 millimeters of H2O or less. Even more preferably, the RTD of the upstream element is about 2 millimeters of H2O or less.

[0123] The RTD of the upstream element can be at least 0.1 millimeters H2O, or at least about 0.25 millimeters H2O, or at least about 0.5 millimeters H2O.

[0124] In some embodiments, the RTD of the upstream element is from about 0.1 millimeters HO to about 10 millimeters HO, preferably from about 0.25 millimeters HO to about 10 millimeters HO, and preferably from about 0.5 millimeters HO to about 10 millimeters HO. In other embodiments, the RTD of the upstream element is from about 0.1 millimeters HO to about 5 millimeters HO, preferably from about 0.25 millimeters HO to about 5 millimeters HO, and preferably from about 0.5 millimeters HO to about 5 millimeters HO. In further embodiments, the RTD of the upstream element is from about 0.1 millimeters HO to about 2.5 millimeters HO, preferably from about 0.25 millimeters HO to about 2.5 millimeters HO, and more preferably from about 0.5 millimeters HO to about 2.5 millimeters HO. In further embodiments, the RTD of the upstream element is from about 0.1 millimeters HO to about 2 millimeters HO, preferably from about 0.25 millimeters HO to about 2 millimeters HO, and more preferably from about 0.5 millimeters HO to about 2 millimeters HO. In particularly preferred embodiments, the RTD of the upstream element is about 1 millimeter HO.

[0125] Preferably, the upstream element has an RTD that is less than about 2 millimeters of H2O per millimeter of length, more preferably less than about 1.5 millimeters of H2O per millimeter of length, more preferably less than about 1 millimeter of H2O per millimeter of length, more preferably less than about 0.5 millimeters of H2O per millimeter of length, more preferably less than about 0.3 millimeters of H2O per millimeter of length, and more preferably less than about 0.2 millimeters of H2O per millimeter of length.

[0126] Preferably, the combined RTD of the upstream section, or upstream element thereof, and the rod of the aerosol-generating substrate is less than about 15 millimeters H2O, more preferably less than about 12 millimeters H2O, more preferably less than about 10 millimeters H2O.

[0127] In particularly preferred embodiments, the upstream element is formed from a hollow tubular segment defining a longitudinal cavity that provides an unrestricted flow channel. In such embodiments, the upstream element can provide protection for the aerosol-generating substrate, as described above, while having a minimal effect on the overall resistance to draw (RTD) and filtration characteristics of the article.

[0128] Preferably, the longitudinal cavity diameter of the hollow tubular segment forming the upstream element is at least about 4 millimeters, more preferably at least about 4.5 millimeters, more preferably at least about 5 millimeters, more preferably at least about 5.5 millimeters. Preferably, the longitudinal cavity diameter is maximized to minimize the RTD of the upstream section or its upstream element. The inner diameter of the upstream element can be about 5.1 mm.

[0129] Preferably, the wall thickness of the hollow tubular segment is less than about 2 millimeters, more preferably less than about 1.5 millimeters, more preferably less than about 1.25 millimeters. The wall thickness of the hollow tubular segment defining the upstream element may be about 1 mm.

[0130] The upstream element of the upstream section may be made of any material suitable for use in an aerosol-generating article. The upstream element 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 element, or support element. Suitable materials for forming the upstream element include filter material, ceramic, polymeric material, cellulose acetate, cardboard, zeolite, or an aerosol-generating substrate. The upstream element may comprise a cellulose acetate plug. The upstream element may comprise a hollow acetate tube or a cardboard tube.

[0131] The upstream element is preferably formed from a heat resistant material, for example, the upstream element is preferably formed from a material that can withstand temperatures up to 350° C. This ensures that the upstream element is not adversely affected by the heating means for heating the aerosol-generating substrate.

[0132] The upstream section, or upstream element thereof, preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The outer diameter of the upstream section, or upstream element thereof, is preferably from about 6 millimeters to about 8 millimeters, more preferably from about 7 millimeters to about 7.5 millimeters. Preferably, the upstream section or upstream element has an outer diameter of about 7.1 mm.

[0133] Preferably, the upstream section or element has a length of about 2 millimeters to about 8 millimeters, more preferably about 3 millimeters to about 7 millimeters, and even more preferably about 4 millimeters to about 6 millimeters. In a particularly preferred embodiment, the upstream section or element has a length of about 5 millimeters. The length of the upstream section or element can be advantageously varied to provide a desired overall length of 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 section or element can be increased to maintain the same overall length of the article.

[0134] Furthermore, the length of the upstream section, or upstream element thereof, can be used to control the position of the aerosol-generating article within the cavity of the aerosol-generating device for articles intended to be heated externally. This can advantageously ensure that the position of the aerosol-generating substrate within the cavity can be optimized for heating, and the position of any ventilation can also be optimized.

[0135] The upstream section is preferably surrounded by a wrapper, such as plug wrap. The wrapper surrounding the upstream element is preferably a stiff plug wrap, for example, 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, which provides structural rigidity to the upstream section.

[0136] The upstream section is preferably connected to the rod of the aerosol-generating substrate, and optionally to at least part of the downstream section, by an outer wrapper as described herein.

[0137] As described above, the aerosol-generating article according to the present invention comprises a downstream section located downstream of the rod of aerosol-generating substrate. The downstream section is preferably located immediately downstream of the rod of aerosol-generating substrate. The downstream section of the aerosol-generating article preferably extends between the rod of aerosol-generating substrate and the downstream end of the aerosol-generating article. The downstream section may comprise one or more elements, each of which is described in more detail within this disclosure.

[0138] The length of the downstream section may be at least about 20 mm. The length of the downstream section may be at least about 24 mm. The length of the downstream section may be at least about 26 mm.

[0139] The length of the downstream section may be less than or equal to (i.e., not exceeding) about 36 mm. The length of the downstream section may be less than or equal to about 32 mm. The length of the downstream section may be less than or equal to about 30 mm.

[0140] The length of the downstream section can be from about 20 mm to about 36 mm. The length of the downstream section can be from about 24 mm to about 32 mm. The length of the downstream section can be from about 26 mm to about 30 mm.

[0141] Preferably, the downstream section comprises a hollow tubular element. Preferably, the downstream section comprises a mouthpiece element. In a preferred embodiment of the invention, the downstream section comprises or consists of a hollow tubular element and a mouthpiece element, the hollow tubular element being located between the rod of the aerosol-generating substrate and the mouthpiece element.

[0142] In embodiments where the downstream section includes a hollow tubular element and a mouthpiece element, the combined total or overall length of the hollow tubular element and the mouthpiece element may be at least about 20 mm. In other words, the sum of the lengths of the hollow tubular element and the mouthpiece element may be at least about 20 mm. The combined length of the hollow tubular element and the mouthpiece element may be at least about 24 mm. The combined length of the hollow tubular element and the mouthpiece element may be at least about 26 mm.

[0143] The combined length of the hollow tubular element and the mouthpiece element may be about 36 mm or less. The combined length of the hollow tubular element and the mouthpiece element may be about 32 mm or less. The combined length of the hollow tubular element and the mouthpiece element may be about 30 mm or less.

[0144] The combined length of the hollow tubular element and the mouthpiece element can be about 20 mm to about 36 mm. The combined length of the hollow tubular element and the mouthpiece element can be about 24 mm to about 32 mm. The combined length of the hollow tubular element and the mouthpiece element can be about 26 mm to about 30 mm.

[0145] The combined length of the hollow tubular element and the mouthpiece element is preferably about 28 mm.

[0146] In embodiments where the downstream section consists of a hollow tubular element and a mouthpiece element, the length of the downstream section is defined by the combined length of the hollow tubular element and the mouthpiece element.

[0147] Providing a relatively long downstream section, which may be defined by a relatively long combination of the hollow tubular element and the mouthpiece element, ensures that a suitable length of the aerosol-generating article protrudes from the aerosol-generating device when the article is received therein. Such an appropriate protrusion length facilitates insertion and withdrawal of the article from the device and also ensures that the upstream portion of the article is suitably inserted into the device with reduced risk of damage, particularly during insertion.

[0148] The ratio between the length of the downstream section and the overall length of the aerosol-generating article may be about 0.80 or less. Preferably, the ratio between the length of the downstream section and the overall length of the aerosol-generating article may be about 0.75 or less. More preferably, the ratio between the length of the downstream section and the overall length of the aerosol-generating article may be about 0.70 or less. Even more preferably, the ratio between the length of the downstream section and the overall length of the aerosol-generating article may be about 0.65 or less.

[0149] The ratio between the length of the downstream section and the overall length of the aerosol-generating article may be at least about 0.30. Preferably, the ratio between the length of the downstream section and the overall length of the aerosol-generating article may be at least about 0.40. More preferably, the ratio between the length of the downstream section and the overall length of the aerosol-generating article may be at least about 0.50. Even more preferably, the ratio between the length of the downstream section and the overall length of the aerosol-generating article may be at least about 0.60.

[0150] In some embodiments, the ratio between the length of the downstream section and the overall length of the aerosol-generating article is about 0.30 to about 0.80, preferably about 0.40 to about 0.80, more preferably about 0.50 to about 0.80, and even more preferably about 0.60 to about 0.80. In other embodiments, the ratio between the length of the downstream section and the overall length of the aerosol-generating article is about 0.30 to about 0.75, preferably about 0.40 to about 0.75, more preferably about 0.50 to about 0.75, and even more preferably about 0.60 to about 0.75. In further embodiments, the ratio between the length of the downstream section and the overall length of the aerosol-generating article is about 0.30 to about 0.70, preferably about 0.40 to about 0.70, more preferably about 0.50 to about 0.70, and even more preferably about 0.60 to about 0.70. As an example, the ratio between the length of the downstream section and the total length of the aerosol-generating article may be about 0.60 to 0.65, and more preferably, the ratio between the length of the downstream section and the total length of the aerosol-generating article may be 0.62.

[0151] The ratio between the length of the downstream section and the length of the upstream section may be about 18 or less. Preferably, the ratio between the length of the downstream section and the length of the upstream section may be about 12 or less. More preferably, the ratio between the length of the downstream section and the length of the upstream section may be about 8 or less. Even more preferably, the ratio between the length of the downstream section and the length of the upstream section may be about 6 or less.

[0152] The ratio between the length of the downstream section and the length of the upstream section may be at least about 2.5. Preferably, the ratio between the length of the downstream section and the length of the upstream section may be at least about 3. More preferably, the ratio between the length of the downstream section and the length of the upstream section may be at least about 4. Even more preferably, the ratio between the length of the downstream section and the length of the upstream section may be at least about 5.

[0153] In some embodiments, the ratio between the length of the downstream section and the length of the upstream section is about 2.5 to about 18, preferably about 3 to about 18, more preferably about 4 to about 18, and even more preferably about 5 to about 18. In other embodiments, the ratio between the length of the downstream section and the length of the upstream section is about 2.5 to about 12, preferably about 3 to about 12, more preferably about 4 to about 12, and even more preferably about 5 to about 12. In further embodiments, the ratio between the length of the downstream section and the length of the upstream section is about 2.5 to about 8, preferably about 3 to about 8, more preferably about 4 to about 8, and even more preferably about 5 to about 8. As an example, the ratio between the length of the downstream section and the length of the upstream section can be about 6, and even more preferably about 5.6.

[0154] The ratio between the length of the aerosol-generating element (in other words, the rod of the aerosol-generating substrate) and the length of the downstream section may be about 0.80 or less. Preferably, the ratio between the length of the aerosol-generating element and the length of the downstream section may be about 0.70 or less. More preferably, the ratio between the length of the aerosol-generating element and the length of the downstream section may be about 0.60 or less. Even more preferably, the ratio between the length of the aerosol-generating element and the length of the downstream section may be about 0.50 or less.

[0155] The ratio between the length of the aerosol generating element and the length of the downstream section may be at least about 0.20. Preferably, the ratio between the length of the aerosol generating element and the length of the downstream section may be at least about 0.25. More preferably, the ratio between the length of the aerosol generating element and the length of the downstream section may be at least about 0.30. Even more preferably, the ratio between the length of the aerosol generating element and the length of the downstream section may be at least about 0.40.

[0156] In some embodiments, the ratio between the length of the aerosol-generating element and the length of the downstream section is about 0.20 to about 0.80, preferably about 0.25 to about 0.80, more preferably about 0.30 to about 0.80, and even more preferably about 0.40 to about 0.80. In other embodiments, the ratio between the length of the aerosol-generating element and the length of the downstream section is about 0.20 to about 0.70, preferably about 0.25 to about 0.70, more preferably about 0.30 to about 0.70, and even more preferably about 0.40 to about 0.70. In further embodiments, the ratio between the length of the aerosol-generating element and the length of the downstream section is about 0.20 to about 0.60, preferably about 0.25 to about 0.60, more preferably about 0.30 to about 0.60, and even more preferably about 0.40 to about 0.60. As an example, the ratio between the length of the aerosol-generating element and the length of the downstream section can be about 0.5, more preferably about 0.45, and even more preferably about 0.43.

[0157] The downstream section of the aerosol-generating article according to the present invention comprises a hollow tubular element. The hollow tubular element is preferably located downstream of the rod of the aerosol-generating substrate. The hollow tubular element may be located immediately downstream of the rod of the aerosol-generating substrate. In other words, the hollow tubular element may abut the downstream end of the rod of the aerosol-generating substrate. The hollow tubular element may define the upstream end of the downstream section of the aerosol-generating article. The hollow tubular element may be located between the rod of the aerosol-generating substrate and the downstream end of the aerosol-generating article. The downstream end of the aerosol-generating article may coincide with the downstream end of the downstream section. Preferably, the downstream section of the aerosol-generating article comprises a single hollow tubular element. In other words, the downstream section of the aerosol-generating article may comprise only one hollow tubular element.

[0158] As used throughout this disclosure, the term "hollow tubular segment" or "hollow tubular element" generally refers to an elongate element that defines a lumen or airflow passage along its longitudinal axis. In particular, the term "tubular" is used hereinafter with reference to a tubular element that has a substantially cylindrical cross-section and defines at least one airflow conduit that establishes uninterrupted fluid communication between the upstream end of the tubular element and the downstream end of the tubular element. However, it will be appreciated that alternative shapes (e.g., alternative cross-sectional shapes) of the tubular segment may be possible. A hollow tubular segment or element may be an individual, discrete element of an aerosol-generating article having a defined length and thickness.

[0159] The internal volume defined by the hollow tubular element may be at least about 100 cubic millimeters. In other words, the volume of the cavity or lumen defined by the hollow tubular element may be at least about 100 cubic millimeters. Preferably, the internal volume defined by the hollow tubular element may be at least about 300 cubic millimeters. The internal volume defined by the hollow tubular element may be at least about 700 cubic millimeters.

[0160] The interior volume defined by the hollow tubular element may be about 1200 cubic millimeters or less. Preferably, the interior volume defined by the hollow tubular element may be about 1000 cubic millimeters or less. The interior volume defined by the hollow tubular element may be about 900 cubic millimeters or less.

[0161] The interior volume defined by the hollow tubular element can be from about 100 to about 1200 cubic millimeters. Preferably, the interior volume defined by the hollow tubular element can be from about 300 to about 1000 cubic millimeters. The interior volume defined by the hollow tubular element can be from about 700 to about 900 cubic millimeters.

[0162] In the context of the present invention, a hollow tubular segment provides an unrestricted flow channel. This means that the hollow tubular segment provides a negligible resistance to withdrawal (RTD). The term "negligible RTD" is used to describe an RTD of less than 1 mmH2O per 10 millimeters of length of the hollow tubular segment or hollow tubular element, preferably less than 0.4 mmH2O per 10 millimeters of length of the hollow tubular segment or hollow tubular element, and more preferably less than 0.1 mmH2O per 10 millimeters of length of the hollow tubular segment or hollow tubular element.

[0163] The RTD of the hollow tubular element is preferably about 10 millimeters HO or less. More preferably, the RTD of the hollow tubular element is about 5 millimeters HO or less. Even more preferably, the RTD of the hollow tubular element is about 2.5 millimeters HO or less. Even more preferably, the RTD of the hollow tubular element is about 2 millimeters HO or less. Even more preferably, the RTD of the hollow tubular element is about 1 millimeter HO or less.

[0164] The RTD of the hollow tubular element may be at least 0 millimeters H2O, or at least about 0.25 millimeters H2O, or at least about 0.5 millimeters H2O, or at least about 1 millimeter H2O.

[0165] In some preferred embodiments, the RTD of the hollow tubular element is between about 0 millimeters HO and about 10 millimeters HO, preferably between about 0.25 millimeters HO and about 10 millimeters HO, and more preferably between about 0.5 millimeters HO and about 10 millimeters HO. In other embodiments, the RTD of the hollow tubular element is between about 0 millimeters HO and about 5 millimeters HO, preferably between about 0.25 millimeters HO and about 5 millimeters HO, and more preferably between about 0.5 millimeters HO and about 5 millimeters HO. In other embodiments, the RTD of the hollow tubular element is between about 1 millimeter HO and about 5 millimeters HO. In further embodiments, the RTD of the hollow tubular element is between about 0 millimeters HO and about 2.5 millimeters HO, preferably between about 0.25 millimeters HO and about 2.5 millimeters HO, and more preferably between about 0.5 millimeters HO and about 2.5 millimeters HO. In further embodiments, the RTD of the hollow tubular element is from about 0 millimeters HO to about 2 millimeters HO, preferably from about 0.25 millimeters HO to about 2 millimeters HO, and more preferably from about 0.5 millimeters HO to about 2 millimeters HO. In particularly preferred embodiments, the RTD of the hollow tubular element is about 0 millimeters HO.

[0166] In an aerosol-generating article according to the present invention, the overall RTD of the article depends essentially on the RTD of the rod and, optionally, the RTD of the mouthpiece element and / or the upstream element, since the hollow tubular segment is substantially empty and therefore makes only a substantially small contribution to the overall RTD of the aerosol-generating article.

[0167] Therefore, the flow channels should not include any components that would impede the longitudinal air flow. Preferably, the flow channels are substantially empty.

[0168] As used herein, a "hollow tubular segment" or "hollow tubular element" may also be referred to as a "hollow tube" or "hollow tube segment."

[0169] The hollow tubular element may comprise one or more hollow tubular segments. Preferably, the hollow tubular element consists of one (single) hollow tubular segment. Preferably, the hollow tubular element consists of a continuous hollow tubular segment. The hollow tubular segment may include any of the features described in this disclosure in relation to hollow tubular elements.

[0170] As described in more detail within this disclosure, the aerosol-generating article may include a ventilation zone located along the downstream section. More specifically, the aerosol-generating article may include a ventilation zone located along the hollow tubular element. Such a ventilation zone, or any ventilation zone, may extend through the peripheral wall of the hollow tubular element. Thus, fluid communication is established between the flow channel defined internally by the hollow tubular element and the external environment. Ventilation zones are described further within this disclosure.

[0171] The hollow tubular element may have a length of at least about 15 mm. The hollow tubular element may have a length of at least about 17 mm. The hollow tubular element may have a length of at least about 19 mm.

[0172] The hollow tubular element may have a length of about 30 mm or less. The hollow tubular element may have a length of about 25 mm or less. The hollow tubular element may have a length of about 23 mm or less.

[0173] The length of the hollow tubular element can be between about 15 mm and 30 mm. The length of the hollow tubular element can be between about 17 mm and 25 mm. The length of the hollow tubular element can be between about 19 mm and 23 mm.

[0174] Preferably, the length of the hollow tubular element may be about 21 mm.

[0175] The relatively long hollow tubular element provides and defines a relatively long internal cavity within the aerosol-generating article and downstream of the rod of the aerosol-generating substrate. As discussed in this disclosure, providing an empty cavity downstream (preferably immediately downstream) of the aerosol-generating substrate improves nucleation of aerosol particles generated by the substrate. Providing a relatively long cavity maximizes the benefits of such nucleation, thereby improving aerosol formation and cooling.

[0176] The ratio between the length of the aerosol-generating element (in other words, the rod of the aerosol-generating substrate) and the length of the hollow tubular element may be about 1.25 or less. Preferably, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element may be about 1 or less. More preferably, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element may be about 0.75 or less. Even more preferably, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element may be about 0.60 or less.

[0177] The ratio between the length of the aerosol-generating element and the length of the hollow tubular element may be at least about 0.25. Preferably, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element may be at least about 0.30. More preferably, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element may be at least about 0.40. Even more preferably, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element may be at least about 0.50.

[0178] In some embodiments, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element is about 0.25 to about 1.25, preferably about 0.30 to about 1.25, more preferably about 0.40 to about 1.25, and even more preferably about 0.50 to about 1.25. In other embodiments, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element is about 0.25 to about 1, preferably about 0.30 to about 1, more preferably about 0.40 to about 1, and even more preferably about 0.50 to about 1. In further embodiments, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element is about 0.25 to about 0.75, preferably about 0.30 to about 0.75, more preferably about 0.40 to about 0.75, and even more preferably about 0.50 to about 0.75. As an example, the ratio between the length of the aerosol-generating element and the length of the hollow tubular element can be about 0.6, and more preferably about 0.57.

[0179] The ratio between the length of the hollow tubular element and the length of the downstream section may be about 1 or less. Preferably, the ratio between the length of the hollow tubular element and the length of the downstream section may be about 0.90 or less. More preferably, the ratio between the length of the hollow tubular element and the length of the downstream section may be about 0.85 or less. Even more preferably, the ratio between the length of the hollow tubular element and the length of the downstream section may be about 0.80 or less.

[0180] The ratio between the length of the hollow tubular element and the length of the downstream section may be at least about 0.35. Preferably, the ratio between the length of the hollow tubular element and the length of the downstream section may be at least about 0.45. More preferably, the ratio between the length of the hollow tubular element and the length of the downstream section may be at least about 0.50. Even more preferably, the ratio between the length of the hollow tubular element and the length of the downstream section may be at least about 0.60.

[0181] In some embodiments, the ratio between the length of the hollow tubular element and the length of the downstream section is about 0.35 to about 1, preferably about 0.45 to about 1, more preferably about 0.50 to about 1, and even more preferably about 0.60 to about 1. In other embodiments, the ratio between the length of the hollow tubular element and the length of the downstream section is about 0.35 to about 0.90, preferably about 0.45 to about 0.90, more preferably about 0.50 to about 0.90, and even more preferably about 0.60 to about 0.90. In further embodiments, the ratio between the length of the hollow tubular element and the length of the downstream section is about 0.35 to about 0.85, preferably about 0.45 to about 0.85, more preferably about 0.50 to about 0.85, and even more preferably about 0.60 to about 0.85. As an example, the ratio between the length of the hollow tubular element and the length of the downstream section may preferably be about 0.75.

[0182] The ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be about 0.80 or less. Preferably, the ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be about 0.70 or less. More preferably, the ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be about 0.60 or less. Even more preferably, the ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be about 0.50 or less.

[0183] The ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be at least about 0.25. Preferably, the ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be at least about 0.30. More preferably, the ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be at least about 0.40. Even more preferably, the ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be at least about 0.45.

[0184] In some embodiments, the ratio between the length of the hollow tubular element and the total length of the aerosol-generating article is about 0.25 to about 0.80, preferably about 0.30 to about 0.80, more preferably about 0.40 to about 0.80, and even more preferably about 0.45 to about 0.80. In other embodiments, the ratio between the length of the hollow tubular element and the total length of the aerosol-generating article is about 0.25 to about 0.70, preferably about 0.30 to about 0.70, more preferably about 0.40 to about 0.70, and even more preferably about 0.45 to about 0.70. In further embodiments, the ratio between the length of the hollow tubular element and the total length of the aerosol-generating article is about 0.25 to about 0.60, preferably about 0.30 to about 0.60, more preferably about 0.40 to about 0.60, and even more preferably about 0.45 to about 0.60. As an example, the ratio between the length of the hollow tubular element and the overall length of the aerosol-generating article may be about 0.5, more preferably about 0.47.

[0185] Providing a downstream section or hollow tubular element with the above ratio maximizes the aerosol cooling and formation benefits of having a relatively long hollow tubular element while providing a sufficient amount of filtration for an aerosol-generating article configured to be heated rather than combusted. Additionally, providing a longer hollow tubular element can advantageously lower the effective RTD of the downstream section of the aerosol-generating article, which may be primarily defined by the RTD of the mouthpiece filtering element.

[0186] The thickness of the peripheral wall of the hollow tubular element (in other words, the wall thickness) may be at least about 100 micrometers. The wall thickness of the hollow tubular element may be at least about 150 micrometers. The wall thickness of the hollow tubular element is at least about 200 micrometers, preferably at least about 250 micrometers, and even more preferably at least about 500 micrometers (or 0.5 mm).

[0187] The wall thickness of the hollow tubular element may be about 2 millimeters or less, preferably about 1.5 millimeters or less, and even more preferably about 1.25 mm or less. The wall thickness of the hollow tubular element may be about 1 millimeter or less. The wall thickness of the hollow tubular element may be about 500 micrometers or less.

[0188] The wall thickness of the hollow tubular element may be from about 100 micrometers to about 2 millimeters, preferably from about 150 micrometers to about 1.5 millimeters, and even more preferably from about 200 micrometers to about 1.25 millimeters.

[0189] Preferably, the wall thickness of the hollow tubular element may be about 250 micrometers (0.25 mm).

[0190] At the same time, maintaining a relatively low peripheral wall thickness of the hollow tubular segment effectively maximizes the overall internal volume of the hollow tubular segment and the cross-sectional area of ​​the hollow tubular segment, which are available for the aerosol to initiate the nucleation process as soon as the aerosol components leave the aerosol-generating substrate rod, 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 minimizes the RTD of the hollow tubular segment. 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 improve the cooling effect on the formation of new aerosol particles.

[0191] The hollow tubular element 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.

[0192] The hollow tubular element may have an outer diameter of 5 millimeters to 12 millimeters, for example, an outer diameter of 5 millimeters to 10 millimeters, or an outer diameter of 6 millimeters to 8 millimeters. In a preferred embodiment, the hollow tubular element has an outer diameter of 7.2 millimeters ± 10 percent.

[0193] The hollow tubular element may have an inner diameter. Preferably, the hollow tubular element may have a constant inner diameter along the length of the hollow tubular element. However, the inner diameter of the hollow tubular element may vary along the length of the hollow tubular element.

[0194] The hollow tubular element may have an inner diameter of at least about 2 millimeters. For example, the hollow tubular element may have an inner diameter of at least about 4 millimeters, or at least about 5 millimeters, or at least about 7 millimeters.

[0195] Providing a hollow tubular element with the above-mentioned inner diameter may advantageously provide the hollow tubular element with sufficient stiffness and strength.

[0196] The hollow tubular element can have an inner diameter of about 10 millimeters or less. For example, the hollow tubular element can have an inner diameter of about 9 millimeters or less, about 8 millimeters or less, or about 7.5 millimeters or less.

[0197] Providing a hollow tubular element with the above-mentioned inner diameter may advantageously reduce the resistance to withdrawal of the hollow tubular segment.

[0198] The hollow tubular element may have an inner diameter of about 2 millimeters to about 10 millimeters, about 4 millimeters to about 9 millimeters, about 5 millimeters to about 8 millimeters, or about 6 millimeters to about 7.5 millimeters.

[0199] The hollow tubular element may have an outer diameter of about 7.1 or 7.2 mm. The hollow tubular element may have an inner diameter of about 6.7 millimeters.

[0200] The ratio between the inner diameter of the hollow tubular element and the outer diameter of the hollow tubular element can be at least about 0.8. For example, the ratio between the inner diameter of the hollow tubular element and the outer diameter of the hollow tubular element can be at least about 0.85, at least about 0.9, or at least about 0.95.

[0201] The ratio between the inner diameter of the hollow tubular element and the outer diameter of the hollow tubular element may be about 0.99 or less. For example, the ratio between the inner diameter of the hollow tubular element and the outer diameter of the hollow tubular element may be about 0.98 or less.

[0202] The ratio between the inner diameter of the hollow tubular element and the outer diameter of the hollow tubular element may be about 0.97.

[0203] Providing a relatively large inner diameter may advantageously reduce the resistance to drawing the hollow tubular segment and improve cooling and nucleation of the aerosol particles.

[0204] The lumen or cavity of the hollow tubular segment may have any cross-sectional shape. The lumen of the hollow tubular segment may have a circular cross-sectional shape.

[0205] The hollow tubular segment may comprise a paper-based material. The hollow tubular segment may comprise at least one layer of paper. The paper may be a very stiff paper. The paper may be a crimped paper, such as crimped heat-resistant paper or crimped parchment paper.

[0206] Preferably, the hollow tubular element may comprise cardboard. The hollow tubular element may be a cardboard tube. The hollow tubular element may be formed from cardboard. Advantageously, cardboard is a cost-effective material that provides a balance between being deformable to facilitate insertion of an article into the aerosol generating device and being rigid enough to adequately engage the article with the interior of the device. Thus, a cardboard tube may provide suitable resistance to deformation or compression during use.

[0207] The hollow tubular segment may be a paper tube. The hollow tubular segment may be a tube formed from spirally wound paper. The hollow tubular segment may be formed from multiple layers of paper. The paper may have a basis weight of at least about 50 grams per square meter, at least about 60 grams per square meter, at least about 70 grams per square meter, or at least about 90 grams per square meter.

[0208] The hollow tubular segment may comprise a polymeric material. For example, the hollow tubular segment may comprise a polymeric film. The polymeric film may comprise a cellulose film. The hollow tubular segment may comprise low-density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may comprise cellulose acetate tow.

[0209] When the hollow tubular segment comprises cellulose acetate tow, the cellulose acetate tow may have a denier per filament of from about 2 to about 4 and a total denier of from about 25 to about 40.

[0210] As described above, the aerosol-generating article of the present invention comprises a downstream section comprising a hollow tubular element located downstream of the rod of aerosol-generating substrate and abutting the downstream end of the rod of aerosol-generating substrate. The aerosol-generating article of the present invention further comprises a ventilation zone located along the hollow tubular element.

[0211] Thus, the vented cavity is located downstream of the rod of the aerosol-generating substrate, which offers several potential technical advantages.

[0212] First, the inventors have found that such a single vented hollow tubular element provides particularly efficient cooling of the aerosol. Thus, satisfactory cooling of the aerosol can be achieved even using a relatively short downstream section. This is particularly desirable because it allows for the provision of an aerosol-generating article in which aerosol-generating substrates (and particularly those containing tobacco) are heated, rather than combusted, combining satisfactory aerosol delivery with efficient cooling of the aerosol to a temperature desirable for the consumer.

[0213] Second, the inventors have surprisingly found that such rapid cooling of volatile species released upon heating of the aerosol-generating substrate promotes nucleation of aerosol particles. This effect is particularly realized when the ventilation zone is located at a precisely defined position along the length of the hollow tubular element relative to other components of the aerosol-generating article, as explained in more detail below. Indeed, the inventors have surprisingly found that the favorable effect of improved nucleation can significantly counteract the potentially undesirable effect of dilution induced by the introduction of ventilation air.

[0214] The distance between the ventilation zone and the upstream end of the downstream section is at least 26 millimeters. As used herein, the term "distance between the ventilation zone and another element or portion of the aerosol-generating article" refers to a distance measurement in the longitudinal direction, i.e., extending along or parallel to the cylindrical axis of the aerosol-generating article.

[0215] Preferably, the distance between the ventilation zone and the upstream end of the upstream section is at least 27 millimeters.

[0216] The distance between the ventilation zone and the upstream end of the upstream element can be 34 millimeters or less. Preferably, the distance between the ventilation zone and the upstream end of the upstream section is 33 millimeters or less. More preferably, the distance between the ventilation zone and the upstream end of the upstream section is 31 millimeters or less.

[0217] In some embodiments, the distance between the ventilation zone and the upstream end of the upstream section is between 25 millimeters and 34 millimeters, preferably between 26 millimeters and 34 millimeters, and more preferably between 27 millimeters and 34 millimeters.

[0218] In other embodiments, the distance between the ventilation zone and the upstream end of the upstream element is between 25 millimeters and 33 millimeters, preferably between 26 millimeters and 33 millimeters, and more preferably between 27 millimeters and 33 millimeters.

[0219] In a further embodiment, the distance between the ventilation zone and the upstream end of the upstream element is between 25 millimeters and 31 millimeters, preferably between 26 millimeters and 31 millimeters, and more preferably between 27 millimeters and 31 millimeters.

[0220] In some particularly preferred embodiments, the distance between the ventilation zone and the upstream end of the upstream element is between 28 millimeters and 30 millimeters.

[0221] It has been found that aerosol-generating articles with ventilation zones located along the hollow tubular element at distances from the upstream end of the upstream element within the above-mentioned ranges offer several benefits.

[0222] First, such articles have been observed to deliver particularly satisfactory aerosols to consumers, especially when the aerosol-generating substrate comprises tobacco.

[0223] Without intending to be bound by theory, it is understood that the intense cooling caused by the ambient air drawn into the cavity of the hollow tubular segment in the ventilation zone accelerates the condensation of droplets of aerosol former (e.g., glycerin) released from the aerosol-generating substrate upon heating. Volatile nicotine and organic acids also released from the tobacco substrate then accumulate on the newly formed droplets of aerosol former and subsequently bind to the nicotine salts. As a result, the overall ratio of aerosol particle phase to aerosol vapor phase may be improved compared to existing aerosol-generating articles.

[0224] Positioning the ventilation zone at the aforementioned distance from the upstream end of the upstream element advantageously reduces the flight time of the volatile nicotine particles before they reach the droplets of the aerosol former, while at the same time ensuring that there is sufficient time and space for nicotine accumulation and nicotine salt formation to occur at a significant rate before the aerosol stream reaches the consumer's mouth.

[0225] The ventilation zone typically comprises a plurality of perforations through the peripheral wall of the hollow tubular element. Preferably, the ventilation zone comprises at least one row of circumferential perforations. In some embodiments, the ventilation zone may comprise two rows of circumferential perforations. For example, the perforations may be formed online during the manufacture of the aerosol-generating article. Preferably, each row of circumferential perforations comprises between 8 and 30 perforations.

[0226] Aerosol-generating articles according to the present invention may have a breathability level of at least about 2 percent.

[0227] The term "ventilation level" is used throughout this specification to refer to 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. The aerosol-generating article preferably has a ventilation level of at least 5 percent, more preferably at least 10 percent, and even more preferably at least 12 percent or at least 15 percent.

[0228] Aerosol-generating articles according to the present invention may have a breathability level of up to about 90 percent. Preferably, aerosol-generating articles according to the present invention have a breathability level of 80 percent or less, more preferably 70 percent or less, even more preferably 60 percent or less, and most preferably 50 percent or less.

[0229] Thus, the aerosol-generating article of the present invention may have a breathability level of 2 to 90 percent, preferably 5 to 90 percent, more preferably 10 to 90 percent, and even more preferably 15 to 90 percent. The aerosol-generating article of the present invention may have a breathability level of 2 to 80 percent, preferably 5 to 80 percent, more preferably 10 to 80 percent, and even more preferably 15 to 80 percent. The aerosol-generating article of the present invention may have a breathability level of 2 to 70 percent, preferably 5 to 70 percent, more preferably 10 to 70 percent, and even more preferably 15 to 70 percent. The aerosol-generating article of the present invention may have a breathability level of 2 to 60 percent, preferably 5 to 60 percent, more preferably 10 to 60 percent, and even more preferably 15 to 60 percent. The aerosol-generating article of the present invention may have a breathability level of 2 to 50 percent, preferably 5 to 50 percent, more preferably 10 to 50 percent, and even more preferably 15 to 50 percent. It is preferred that the aerosol-generating article have a breathability level of 30 percent or less, preferably 25 percent or less, more preferably 20 percent or less, and even more preferably 18 percent or less.

[0230] In some embodiments, the aerosol-generating article has a ventilation level of 10 percent to 30 percent, preferably 12 percent to 30 percent, and more preferably 15 percent to 30 percent. In other embodiments, the aerosol-generating article has a ventilation level of 10 percent to 25 percent, preferably 12 percent to 25 percent, and more preferably 15 percent to 25 percent. In further embodiments, the aerosol-generating article has a ventilation level of 10 percent to 20 percent, preferably 12 percent to 20 percent, and more preferably 15 percent to 20 percent. In some embodiments, the aerosol-generating article has a ventilation level of 10 percent to 18 percent, preferably 12 percent to 18 percent, and more preferably 15 percent to 18 percent.

[0231] 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 element through the ventilation zone can have a beneficial effect on the nucleation and growth of aerosol particles.

[0232] The formation of aerosols from gaseous mixtures containing various chemical species depends on the delicate interplay between nucleation, evaporation, condensation, and even fusion, all of which contribute to 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 kind of critical, threshold molecular cluster within the transient molecular aggregates, which generally means that smaller molecular clusters tend to break down into the gas phase somewhat more quickly, while larger clusters tend to grow more easily. Such 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, raw droplets emerge with a certain original diameter and may subsequently grow by several orders of magnitude. This can be facilitated and improved by rapid cooling of the surrounding vapor, which induces condensation. In this context, it is useful to keep in mind 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.

[0233] In this situation (which may be further complicated by coalescence 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 would appear to be more pronounced at lower temperatures. Furthermore, it appears that a faster cooling rate may be advantageous in that nucleation begins earlier. In contrast, a decrease in the cooling rate appears to have a favorable effect on the final size that the aerosol droplets ultimately reach.

[0234] Thus, the rapid cooling induced by admitting ambient air into the hollow tubular element via the ventilation zone can be advantageously used to favor the nucleation and growth of aerosol droplets. At the same time, however, admitting ambient air into the hollow tubular element has the direct drawback of diluting the aerosol stream delivered to the consumer.

[0235] The inventors have surprisingly found that the favorable effects of improved nucleation, facilitated by the rapid cooling induced by the introduction of ventilation air into the article, can significantly counteract the undesirable effects of such dilution. Thus, satisfactory aerosol delivery values ​​are consistently achieved by the aerosol-generating articles of the present invention.

[0236] The inventors have surprisingly found that measurable dilution effects on the aerosol, particularly the effects on delivery of the aerosol former (such as glycerol) contained in the aerosol-generating substrate, are advantageously minimized when the aeration level is within the ranges described above.

[0237] In particular, aeration levels of 10 percent to 20 percent, and even more preferably 12 to 18 percent, have been found to lead to particularly satisfactory values ​​of glycerin delivery.

[0238] This is particularly advantageous for "short" aerosol-generating articles, including those in which the length of the rod of the aerosol-generating substrate is less than about 40 millimeters, preferably less than 30 millimeters, even more preferably less than 25 millimeters, and especially preferably less than 20 millimeters, or the total length of the aerosol-generating article is 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 typically little time and space for aerosol formation and for the particle phase of the aerosol to become available for delivery to the consumer, and therefore the benefits of improved nucleation discussed above are realized in a particularly pronounced manner.

[0239] Furthermore, because the vented hollow tubular element 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 rods of the aerosol-generating substrate, or the length and, optionally, the length and density of any segment of filtration material forming part of the downstream section, such as the mouthpiece element, or the length and density of the segment of filtration material located upstream of the aerosol-generating substrate and susceptor element. Thus, aerosol-generating articles having a predetermined RTD can be consistently and very accurately manufactured, so that a satisfactory level of RTD can be provided to the consumer even in the presence of ventilation.

[0240] The distance between the ventilation zone and the downstream end of the rod of the aerosol-generating substrate can be at least 4 mm, 6 mm, or 8 mm. Preferably, the distance between the ventilation zone and the downstream end of the rod of the aerosol-generating substrate is at least 9 mm. More preferably, the distance between the ventilation zone and the downstream end of the rod of the aerosol-generating substrate is at least 10 mm.

[0241] Preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod is less than 17 millimeters. More preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod is less than 16 millimeters. Even more preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod is less than 16 millimeters. In a particularly preferred embodiment, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod is less than 15 millimeters.

[0242] In some embodiments, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod is 4 to 17 millimeters, preferably 7 to 17 millimeters, and more preferably 10 to 17 millimeters. In other embodiments, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod is 8 to 16 millimeters, preferably 9 to 16 millimeters, and more preferably 10 to 16 millimeters. In a further embodiment, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod is 8 to 15 millimeters, preferably 9 to 15 millimeters, and more preferably 10 to 15 millimeters. As an example, the distance between the ventilation zone and the downstream end of the aerosol-generating substrate rod may be 10 to 14 millimeters, preferably 10 to 13 millimeters, and more preferably 10 to 12 millimeters. Positioning the ventilation zone at a distance from the downstream end of the aerosol-generating substrate rod within the above-mentioned ranges has the benefit of generally ensuring that, during use, when the aerosol-generating article is inserted into a heating device, the ventilation zone is immediately outside the heating device. Furthermore, it has been found that positioning the ventilation zone at a distance from the downstream end of the rod of the aerosol-generating substrate within the ranges described above can advantageously improve nucleation and aerosol formation and delivery.

[0243] The distance between the ventilation zone and the downstream end of the hollow tubular element can be at least 3 millimeters. Preferably, the distance between the ventilation zone and the downstream end of the hollow tubular element is at least 5 millimeters. More preferably, the distance between the ventilation zone and the downstream end of the hollow tubular element is at least 7 millimeters.

[0244] Preferably, the distance between the ventilation zone and the downstream end of the hollow tubular element is 14 millimeters or less. More preferably, the distance between the ventilation zone and the downstream end of the hollow tubular element is 12 millimeters or less. Even more preferably, the distance between the ventilation zone and the downstream end of the hollow tubular element is 10 millimeters or less.

[0245] In some embodiments, the distance between the ventilation zone and the downstream end of the hollow tubular element is between 3 millimeters and 14 millimeters, preferably between 5 millimeters and 14 millimeters, and more preferably between 7 millimeters and 14 millimeters. In further embodiments, the distance between the ventilation zone and the downstream end of the hollow tubular element is between 3 millimeters and 12 millimeters, preferably between 5 millimeters and 12 millimeters, and more preferably between 7 millimeters and 12 millimeters. In other embodiments, the distance between the ventilation zone and the downstream end of the hollow tubular element is between 3 millimeters and 10 millimeters, preferably between 5 millimeters and 10 millimeters, and more preferably between 7 millimeters and 10 millimeters.

[0246] Positioning the ventilation zone at a distance from the downstream end of the hollow tubular element within the above-mentioned ranges has the benefit of generally ensuring that, in use, when the aerosol-generating article is inserted into the heating device, the ventilation zone is immediately outside the heating device. Furthermore, it has been found that positioning the ventilation zone at a distance from the downstream end of the hollow tubular element within the above-mentioned ranges can advantageously lead to relatively more homogeneous aerosol formation and delivery.

[0247] The distance between the ventilation zone and the downstream end of the aerosol-generating article can be at least 10 millimeters. Preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating article is at least 12 millimeters. More preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating article is at least 15 millimeters.

[0248] Preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating article is 21 millimeters or less. More preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating article is 19 millimeters or less. Even more preferably, the distance between the ventilation zone and the downstream end of the aerosol-generating article is 17 millimeters or less.

[0249] In some embodiments, the distance between the ventilation zone and the downstream end of the aerosol-generating article is between 10 millimeters and 21 millimeters, preferably between 12 millimeters and 21 millimeters, and more preferably between 15 millimeters and 21 millimeters. In further embodiments, the distance between the ventilation zone and the downstream end of the aerosol-generating article is between 10 millimeters and 19 millimeters, preferably between 12 millimeters and 19 millimeters, and more preferably between 15 millimeters and 19 millimeters. In other embodiments, the distance between the ventilation zone and the downstream end of the aerosol-generating article is between 10 millimeters and 17 millimeters, preferably between 12 millimeters and 17 millimeters, and more preferably between 15 millimeters and 17 millimeters.

[0250] Positioning the ventilation zone at a distance from the downstream end of the aerosol-generating article within the above-mentioned ranges has the advantage that, during use, when the aerosol-generating article is partially received within the heating device, the portion of the aerosol-generating article extending outside the heating device is generally long enough for a consumer to comfortably hold the article between their lips. At the same time, evidence suggests that the long length of the portion of the aerosol-generating article extending outside the heating device may make it easier to inadvertently bend the aerosol-generating article to an undesirable extent, which may impair aerosol delivery or, generally, the intended use of the aerosol-generating article.

[0251] As discussed in this disclosure, the downstream section may include a mouthpiece element. The mouthpiece element may extend from a downstream end of the downstream section. The mouthpiece element may be located at the downstream end of the aerosol-generating article. The downstream end of the mouthpiece element may define the downstream end of the aerosol-generating article.

[0252] The mouthpiece element may be located downstream of the rod of the aerosol-generating substrate. The mouthpiece element may extend all the way to the mouth end of the aerosol-generating article. The mouthpiece element may include at least one mouthpiece filter segment formed from a fibrous filtering material. The mouthpiece element may be located downstream of the hollow tubular element described above. The mouthpiece element may extend between the hollow tubular element and the downstream end of the aerosol-generating article.

[0253] Parameters or characteristics described in relation to the mouthpiece element as a whole may be equally applied to the mouthpiece filter segment of the mouthpiece element.

[0254] The fibrous filtration material may be for filtering the aerosol generated from the aerosol-generating substrate. Suitable fibrous filtration materials will be known to those skilled in the art. Particularly preferably, at least one mouthpiece filter segment comprises a cellulose acetate filter segment formed from cellulose acetate tow.

[0255] In certain preferred embodiments, the mouthpiece element comprises a single mouthpiece filter segment, hi alternative embodiments, the mouthpiece element comprises two or more axially aligned mouthpiece filter segments in end-to-end abutting relationship with one another.

[0256] In certain embodiments of the invention, the downstream section may comprise a mouth-end cavity at its downstream end downstream of the mouthpiece element as described above. The mouth-end cavity may be defined by an additional hollow tubular element mounted at the downstream end of the mouthpiece. Alternatively, the mouth-end cavity may be defined by an outer wrapper of the aerosol-generating article, the outer wrapper extending downstream from (or past) the mouthpiece element.

[0257] The mouthpiece element may optionally include a flavorant, which may be provided in any suitable form, for example, the mouthpiece element may include one or more capsules, beads or granules of flavorant, or one or more flavor-containing threads or filaments.

[0258] Preferably, the mouthpiece element, or mouthpiece filter segment thereof, has a low particle filtration efficiency.

[0259] Preferably, the mouthpiece element is surrounded by plug wrap. Preferably, the mouthpiece element is non-vented so that air does not enter the aerosol-generating article along the mouthpiece element.

[0260] The mouthpiece element is preferably connected to one or more of the adjacent upstream components of the aerosol-generating article by a tip wrapper.

[0261] The mouthpiece element preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The diameter of the mouthpiece element (or mouthpiece filter segment) can be substantially the same as the outer diameter of the hollow tubular element. As noted in this disclosure, the outer diameter of the hollow tubular element can be approximately 7.2 mm ± 10 percent.

[0262] The diameter of the mouthpiece element may be about 5 mm to about 10 mm. The diameter of the mouthpiece element may be about 6 mm to about 8 mm. The diameter of the mouthpiece element may be about 7 mm to about 8 mm. The diameter of the mouthpiece element may be about 7.2 mm ± 10 percent. The diameter of the mouthpiece element may be about 7.25 mm ± 10 percent.

[0263] 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 drive air through the entire length of the component. The terms "pressure drop" or "draw resistance" of a component or article may also refer to "resistance to draw." Such terms refer to measurements according to ISO 6565-2015, typically performed under test at a temperature of about 22°C, a pressure of about 101 kPa (about 760 Torr), and a relative humidity of about 60 percent, with a volumetric flow rate of about 17.5 milliliters per second at the output or downstream end of the component being measured.

[0264] The resistance to draw (RTD) of the downstream section may be at least about 0 mmH2O. The RTD of the downstream section may be at least about 3 mmH2O. The RTD of the downstream section may be at least about 6 mmH2O.

[0265] The RTD of the downstream section may be about 12 mmH2O or less. The RTD of the downstream section may be about 11 mmH2O or less. The RTD of the downstream section may be about 10 mmH2O or less.

[0266] The resistance to withdrawal in the downstream section may be greater than or equal to about 0 mmH2O and less than about 12 mmH2O. Preferably, the resistance to withdrawal in the downstream section may be greater than or equal to about 3 mmH2O and less than about 12 mmH2O. The resistance to withdrawal in the downstream section may be greater than or equal to about 0 mmH2O and less than about 11 mmH2O. Even more preferably, the resistance to withdrawal in the downstream section may be greater than or equal to about 3 mmH2O and less than about 11 mmH2O. Even more preferably, the resistance to withdrawal in the downstream section may be greater than or equal to about 6 mmH2O and less than about 10 mmH2O. Preferably, the resistance to withdrawal in the downstream section may be about 8 mmH2O.

[0267] The resistance to withdrawal (RTD) characteristics of the downstream section may be entirely or mostly attributable to the RTD characteristics of the mouthpiece elements of the downstream section, or in other words, the RTD of the mouthpiece elements of the downstream section may completely define the RTD of the downstream section.

[0268] The resistance to draw (RTD) of the mouthpiece element may be at least about 0 mmH2O. The RTD of the mouthpiece element may be at least about 3 mmH2O. The RTD of the mouthpiece element may be at least about 6 mmH2O.

[0269] The RTD of the mouthpiece element may be about 12 mmH2O or less. The RTD of the mouthpiece element may be about 11 mmH2O or less. The RTD of the mouthpiece element may be about 10 mmH2O or less.

[0270] The resistance to withdrawal of the mouthpiece element may be greater than or equal to about 0 mmH2O and less than about 12 mmH2O. Preferably, the resistance to withdrawal of the mouthpiece element may be greater than or equal to about 3 mmH2O and less than about 12 mmH2O. The resistance to withdrawal of the mouthpiece element may be greater than or equal to about 0 mmH2O and less than about 11 mmH2O. Even more preferably, the resistance to withdrawal of the mouthpiece element may be greater than or equal to about 3 mmH2O and less than 11 mmH2O. Even more preferably, the resistance to withdrawal of the mouthpiece element may be greater than or equal to about 6 mmH2O and less than about 10 mmH2O. Preferably, the resistance to withdrawal of the mouthpiece element may be about 8 mmH2O.

[0271] As described above, the mouthpiece element or mouthpiece filter segment may be formed from a fibrous material. The mouthpiece element may be formed from a porous material. The mouthpiece element may be formed from a biodegradable material. The mouthpiece element may be formed from a cellulose material, such as cellulose acetate. For example, the mouthpiece element may be formed from a bundle of cellulose acetate fibers having a denier per filament of about 10 to about 15. For example, the mouthpiece element may be formed from a relatively low-density cellulose acetate tow, such as a cellulose acetate tow containing fibers of about 12 denier per filament.

[0272] The mouthpiece element may be formed of a polylactic acid material. The mouthpiece element may be formed of a bioplastic material, preferably a starch-based bioplastic material. The mouthpiece element may be fabricated by injection molding or extrusion. Bioplastic-based materials are advantageous because they may include multiple relatively large airflow channels extending through the material of the mouthpiece element, providing a simple and inexpensive mouthpiece element structure with a specific and complex cross-sectional profile that provides suitable RTD characteristics.

[0273] The mouthpiece element may be formed from a sheet of suitable material that is crimped, pleated, gathered, woven, or folded into an element that defines a plurality of longitudinally extending channels. Such a sheet of suitable material may be formed from paper, cardboard, a polymer such as polylactic acid, or any other cellulosic, paper-based, or bioplastic-based material. The cross-sectional profile of such a mouthpiece element may exhibit randomly oriented channels.

[0274] The mouthpiece element may be formed in any other suitable manner. For example, the mouthpiece element may be formed from a bundle of longitudinally extending tubes. The longitudinally extending tubes may be formed from polylactic acid. The mouthpiece element may be formed by extrusion, molding, lamination, injection, or milling of a suitable material. Therefore, it is preferred that there is a low pressure drop (or RTD) from the upstream end of the mouthpiece element to the downstream end of the mouthpiece element.

[0275] The length of the mouthpiece element may be at least about 3 mm. The length of the mouthpiece element may be at least about 5 mm. The length of the mouthpiece element may be about 11 mm or less. The length of the mouthpiece element may be about 9 mm or less. The length of the mouthpiece element may be between about 3 mm and about 11 mm. The length of the mouthpiece element may be between about 5 mm and about 9 mm. Preferably, the length of the mouthpiece element may be about 7 mm.

[0276] The ratio between the length of the mouthpiece element and the length of the downstream section may be about 0.55 or less. Preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be about 0.45 or less. More preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be about 0.35 or less. Even more preferably, the ratio between the length of the mouthpiece element and the length of the downstream section is about 0.25 or less.

[0277] The ratio between the length of the mouthpiece element and the length of the downstream section may be at least about 0.05. Preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be at least about 0.10. More preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be at least about 0.15. Even more preferably, the ratio between the length of the mouthpiece element and the length of the downstream section may be at least about 0.20.

[0278] In some embodiments, the ratio between the length of the mouthpiece element and the length of the downstream section is about 0.05 to about 0.55, preferably about 0.10 to about 0.55, more preferably about 0.15 to about 0.55, and even more preferably about 0.20 to about 0.55. In other embodiments, the ratio between the length of the mouthpiece element and the length of the downstream section is about 0.05 to about 0.45, preferably about 0.10 to about 0.45, more preferably about 0.15 to about 0.45, and even more preferably about 0.20 to about 0.45. In further embodiments, the ratio between the length of the mouthpiece element and the length of the downstream section is about 0.05 to about 0.35, preferably about 0.10 to about 0.35, more preferably about 0.15 to about 0.35, and even more preferably about 0.20 to about 0.35. As an example, the ratio between the length of the mouthpiece element and the length of the downstream section may preferably be about 0.20 to about 0.25, and more preferably the ratio between the length of the mouthpiece element and the length of the downstream section may be about 0.25.

[0279] The ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be about 0.40 or less. Preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be about 0.30 or less. More preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be about 0.25 or less. Even more preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be about 0.20 or less.

[0280] The ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be at least about 0.05. Preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be at least about 0.07. More preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be at least about 0.10. Even more preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be at least about 0.15.

[0281] In some embodiments, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article is about 0.05 to about 0.40, preferably about 0.07 to about 0.40, more preferably about 0.10 to about 0.40, and even more preferably about 0.15 to about 0.40. In other embodiments, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article is about 0.05 to about 0.30, preferably about 0.07 to about 0.30, more preferably about 0.10 to about 0.30, and even more preferably about 0.15 to about 0.30. In further embodiments, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article is about 0.05 to about 0.25, preferably about 0.07 to about 0.25, more preferably about 0.10 to about 0.25, and even more preferably about 0.15 to about 0.25. As an example, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be about 0.15 to about 0.20, and more preferably, the ratio between the length of the mouthpiece element and the overall length of the aerosol-generating article may be about 0.16.

[0282] In embodiments in which the downstream section includes a hollow tubular element and a mouthpiece element, the ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 1.25. In other words, the length of the hollow tubular element may be equal to about 125 percent of the length of the mouthpiece. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 1.5. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be at least about 2.

[0283] The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be about 8.5 or less. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be about 6 or less. The ratio of the length of the hollow tubular element to the length of the mouthpiece element may be about 4 or less.

[0284] The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be from about 1.25 to about 8.5. The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be from about 1.5 to about 6. The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be from about 2 to about 4.

[0285] Preferably, the ratio of the length of the hollow tubular element to the length of the mouthpiece element may be about 3. In such an embodiment, the length of the hollow tubular element is about 21 mm and the length of the mouthpiece element is about 7 mm.

[0286] The aerosol-generating article may have a total length of from about 35 millimeters to about 100 millimeters.

[0287] Preferably, the aerosol-generating article of the present invention has a total length of at least about 38 millimeters. More preferably, the aerosol-generating article of the present invention has a total length of at least about 40 millimeters. Even more preferably, the aerosol-generating article of the present invention has a total length of at least about 42 millimeters.

[0288] The overall length of the aerosol-generating article according to the present invention is preferably 70 mm or less, more preferably 60 mm or less, and even more preferably 50 mm or less.

[0289] 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.

[0290] 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.

[0291] 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.

[0292] 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.

[0293] The outer diameter of the aerosol-generating article may be substantially constant along the entire length of the article. Alternatively, different portions of the aerosol-generating article may have different outer diameters.

[0294] In a particularly preferred embodiment, one or more of the components of the aerosol-generating article are individually enclosed by their own wrapper.

[0295] In some embodiments, the rod of aerosol-generating substrate and the mouthpiece element are individually wrapped. The upstream element, the rod of aerosol-generating substrate, and the hollow tubular element are then combined together with an outer wrapper. They are then combined with the mouthpiece element with its own wrapper using tipping paper.

[0296] Preferably, at least one of the components of the aerosol-generating article is enclosed in a hydrophobic wrapper.

[0297] The term "hydrophobicity" refers to a surface that exhibits water-repellent properties. One useful way to determine this is by measuring the water contact angle. The "water contact angle" is traditionally measured by passing a liquid through it and is the angle at which the liquid / vapor interface intersects with a solid surface. It 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, and the resulting interfacial contact angle is expressed in degrees and can range from approximately 0 to approximately 180 degrees.

[0298] In a preferred embodiment, the hydrophobic wrapper comprises a layer of paper having 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.

[0299] As an example, the paper layer may include 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.

[0300] In a particularly preferred embodiment, an aerosol-generating article according to the present invention comprises, in a linear, sequential arrangement, an upstream element, a rod of aerosol-generating substrate located immediately downstream of the upstream element, a hollow tubular element located immediately downstream of the rod of aerosol-generating substrate, a mouthpiece element located immediately downstream of the aerosol-cooling element, and one or more outer wrappers incorporating the upstream element, the rod of aerosol-generating substrate, the hollow tubular element, and the mouthpiece element. The upstream element defines the upstream section of the aerosol-generating article. The hollow tubular element and the mouthpiece element form the downstream section of the aerosol-generating article.

[0301] The rod of the aerosol-generating substrate may abut against the upstream element. The hollow tubular element may abut against the rod of the aerosol-generating substrate. The mouthpiece element may abut against the hollow tubular element. Preferably, the hollow tubular element abuts against the rod of the aerosol-generating substrate and the mouthpiece element abuts against the hollow tubular element.

[0302] The aerosol-generating article has a substantially cylindrical shape and an outer diameter of about 7.23 millimeters.

[0303] The upstream element defined within the upstream section has a length of 5 mm, the rod of the aerosol-generating article has a length of 12 mm, the hollow tubular element has a length of 21 mm, and the mouthpiece element has a length of 7 mm. Thus, the length of the downstream section is 28 mm, and the total length of the aerosol-generating article is approximately 45 mm. Thus, the combined length of the hollow tubular element and the mouthpiece element is 28 mm.

[0304] The upstream element is in the form of a hollow plug of cellulose acetate tow encased in a stiff plug wrap.

[0305] The rod of aerosol-generating substrate comprises at least one of the types of aerosol-generating substrates described above, and preferably shredded tobacco material. In a preferred embodiment, the rod of aerosol-generating substrate comprises 150 milligrams of shredded tobacco material containing 13 to 18 percent by weight of glycerol.

[0306] More particularly, the hollow tubular element is in the form of a cardboard tube and has an internal diameter of about 6.7 millimeters, and the peripheral wall thickness of the hollow tubular element is therefore about 0.25 millimeters.

[0307] A ventilation zone comprising a row of circumferential openings is located along the hollow tubular element 12 millimeters from the upstream end of the hollow tubular element and 29 millimeters from the upstream end of the upstream element.

[0308] The mouthpiece is in the form of a low density cellulose acetate filter segment.

[0309] As mentioned above, the present disclosure also relates to an aerosol generation system including an aerosol generating device having a distal end and a mouth end. The aerosol generating device may include a body. The body or housing of the aerosol generating device may define a device cavity for removably receiving an aerosol-generating article at the mouth end of the device. The aerosol generating device may include a heating element or heater for heating the aerosol-generating substrate when the aerosol-generating article is received within the device cavity.

[0310] The device cavity may be referred to as the heating chamber of the aerosol-generating device. The device cavity may extend between a distal end and an oral or proximal end. The distal end of the device cavity may be a closed end, and the oral or proximal end of the device cavity may be an open end. The aerosol-generating article may be inserted into the device cavity or heating chamber through the open end of the device cavity. The device cavity may be cylindrical in shape to fit the same shape of the aerosol-generating article.

[0311] The phrase "received within" can refer to the fact that a component or element is completely or partially received within another component or element. For example, the phrase "an aerosol-generating article is received within a device cavity" refers to the aerosol-generating article being completely or partially received within the device cavity of the aerosol-generating article. When the aerosol-generating article is received within the device cavity, the aerosol-generating article may abut the distal end of the device cavity. When the aerosol-generating article is received within the device cavity, the aerosol-generating article may be substantially proximate to the distal end of the device cavity. The distal end of the device cavity may be defined by an end wall.

[0312] The length of the device cavity may be about 10 mm to about 50 mm. The length of the device cavity may be about 20 mm to about 40 mm. The length of the device cavity may be about 25 mm to about 30 mm.

[0313] The length of the device cavity (heating chamber) may be the same as or longer than the length of the rod of the aerosol-generating substrate. The length of the device cavity may be the same as or longer than the combined length of the upstream section or element and rod of the aerosol-generating substrate. The length of the device cavity may be determined so that, when an aerosol-generating article is received within the device cavity, the downstream section, or a portion thereof, protrudes from the device cavity. The length of the device cavity may be determined so that, when an aerosol-generating article is received within the device cavity, a portion of the downstream section (such as a hollow tubular element or a mouthpiece element) protrudes from the device cavity. The length of the device cavity may be determined so that, when an aerosol-generating article is received within the device cavity, a portion of the downstream section (such as a hollow tubular element or a mouthpiece element) is received within the device cavity.

[0314] At least 25 percent of the length of the downstream section may be inserted or received within the device cavity when an aerosol-generating article is received within the device. At least 30 percent of the length of the downstream section may be inserted or received within the device cavity when an aerosol-generating article is received within the device.

[0315] At least 30 percent of the length of the hollow tubular element may be inserted or received within the device cavity when an aerosol-generating article is received within the device. At least 40 percent of the length of the hollow tubular element may be inserted or received within the device cavity when an aerosol-generating article is received within the device. At least 50 percent of the length of the hollow tubular element may be inserted or received within the device cavity when an aerosol-generating article is received within the device. Various lengths of hollow tubular elements are described in more detail within this disclosure.

[0316] Optimizing the amount or length of an article inserted into an aerosol-generating device can increase the resistance of the article to inadvertent detachment during use. In particular, during heating of the aerosol-generating substrate, the substrate can shrink such that its outer diameter can decrease, thereby reducing the extent to which the insert portion of an article inserted into the device can frictionally engage with the device cavity. The insert portion of the article, or the portion of the article configured to be received within the device cavity, can be the same length as the device cavity.

[0317] Preferably, the length of the device cavity is about 25 mm to about 29 mm. More preferably, the length of the device cavity is about 26 mm to about 29 mm. Even more preferably, the length of the device cavity is about 27 mm or about 28 mm.

[0318] Preferably, the combined length of the upstream section (or element) and the downstream section or inserted portion of the hollow tubular element is equal to about 80 percent to about 120 percent of the length of the protruding portion of the aerosol-generating article. The downstream section or inserted portion of the hollow tubular element or aerosol-generating article refers to the portion of the downstream section or hollow tubular element or aerosol-generating article that is configured to be positioned within the device cavity when the aerosol-generating article is received therein. The protruding portion of the aerosol-generating article refers to the article that is configured to be positioned outside the device cavity or to protrude from the device when the aerosol-generating article is received therein. The inventors have found that this relationship minimizes the risk of the article inadvertently becoming detached from the device during use, particularly after the article may contract during use. Preferably, the portion of the aerosol-generating article that is configured to be inserted into the device is longer than the portion of the aerosol-generating article that is configured to protrude from the device when the aerosol-generating article is received within the aerosol-generating device.

[0319] The diameter of the device cavity may be about 4 mm to about 10 mm. The diameter of the device cavity may be about 5 mm to about 9 mm. The diameter of the device cavity may be about 6 mm to about 8 mm. The diameter of the device cavity may be about 7 mm to about 8 mm. The diameter of the device cavity may be about 7 mm to about 7.5 mm.

[0320] The diameter of the device cavity may be substantially the same as or larger than the diameter of the aerosol-generating article. The diameter of the device cavity may be the same as the diameter of the aerosol-generating article to establish a tight fit with the aerosol-generating article.

[0321] The device cavity may be configured to establish an interference fit with an aerosol-generating article received within the device cavity. An interference fit may refer to a slip fit. The aerosol-generating device may include a peripheral wall. Such a peripheral wall may define the device cavity, or a heating chamber. The peripheral wall defining the device cavity may be configured to engage in a tight fit with the aerosol-generating article received within the device cavity such that, when received within the device, there is substantially no gap or empty space between the peripheral wall defining the device cavity and the aerosol-generating article.

[0322] Such an interference fit may establish an airtight fit or configuration between the device cavity and the aerosol-generating article received therein.

[0323] In such an airtight configuration, there will be substantially no gaps or empty spaces between the peripheral walls defining the device cavity and the aerosol-generating article through which the air flows.

[0324] The interference fit with the aerosol-generating article may be established along the entire length of the device cavity or along a portion of the length of the device cavity.

[0325] The aerosol generating device may include an airflow channel extending between the channel inlet and the channel outlet. The airflow channel may be configured to establish fluid communication between the interior of the device cavity and the exterior of the aerosol generating device. The airflow channel of the aerosol generating device may be defined within the housing of the aerosol generating device to enable fluid communication between the interior of the device cavity and the exterior of the aerosol generating device. When an aerosol-generating article is received within the device cavity, the airflow channel may be configured to provide airflow through the article to deliver the generated aerosol to a user who inhales through the mouth end of the article.

[0326] The airflow channel of the aerosol generating device may be defined within or by the peripheral wall of the housing of the aerosol generating device. In other words, the airflow channel of the aerosol generating device may be defined within the thickness of the peripheral wall, or by the inner surface of the peripheral wall, or a combination of both. The airflow channel may be partially defined by the inner surface of the peripheral wall and partially defined within the thickness of the peripheral wall. The inner surface of the peripheral wall defines the periphery of the device cavity.

[0327] The airflow channel of the aerosol generating device may extend from an inlet located at the oral or proximal end of the aerosol generating device to an outlet located away from the oral end of the device. The airflow channel may extend along a direction parallel to the longitudinal axis of the aerosol generating device.

[0328] The heater can be any suitable type of heater, although in the present invention it is preferred that the heater is an external heater.

[0329] Preferably, the heater is capable of externally heating the aerosol-generating article when the aerosol-generating article is received within the aerosol-generating device. Such an external heater may surround the aerosol-generating article when inserted into or received within the aerosol-generating device.

[0330] In some embodiments, the heater is arranged to heat the outer surface of the aerosol-generating substrate. In some embodiments, the heater is arranged to be inserted into the aerosol-generating substrate when the aerosol-generating substrate is received within the cavity. The heater may be positioned within the device cavity or heating chamber.

[0331] The heater may include at least one heating element. The at least one heating element may be any suitable type of heating element. In some embodiments, the device includes only one heating element. In some embodiments, the device includes multiple heating elements. The heater may include at least one resistive heating element. Preferably, the heater includes multiple resistive heating elements. The resistive heating elements are preferably electrically connected in a parallel configuration. Advantageously, providing multiple resistive heating elements electrically connected in a parallel configuration may facilitate delivery of desired power to the heater while reducing or minimizing the voltage required to provide the desired power. Advantageously, reducing or minimizing the voltage required to operate the heater may facilitate reducing or minimizing the physical size of the power supply.

[0332] Suitable materials for forming the at least one resistive heating element include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, metal alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminum-, titanium-, zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and stainless steel-based superalloys, Timetal®, and iron-manganese-aluminum-based alloys.

[0333] In some embodiments, the at least one resistive heating element comprises one or more stamped sections of an electrically resistive material (such as stainless steel), or alternatively, the at least one resistive heating element may comprise a heating wire or filament (e.g., Ni-Cr (nickel-chromium), platinum, tungsten, or alloy wire).

[0334] In some embodiments, the at least one heating element comprises an electrically insulating substrate and the at least one resistive heating element is disposed on the electrically insulating substrate.

[0335] The electrically insulating substrate may comprise any suitable material. For example, the electrically insulating substrate may comprise one or more of paper, glass, ceramic, anodized metal, coated metal, and polyimide. The ceramic may comprise mica, alumina (Al2O3), or zirconia (ZrO2). The electrically insulating substrate preferably has a thermal conductivity of about 40 watts per meter Kelvin or less, preferably about 20 watts per meter Kelvin or less, and ideally about 2 watts per meter Kelvin or less.

[0336] The heater may comprise a heating element comprising a rigid, electrically insulating substrate having one or more conductive tracks or wires disposed on its surface. The size and shape of the electrically insulating substrate may allow the heater to be inserted directly into the aerosol-generating substrate. If the electrically insulating substrate is not sufficiently rigid, the heating element may include additional reinforcing means. Electric current may be passed through one or more conductive tracks to heat the heating element and the aerosol-generating substrate.

[0337] In some embodiments, the heater comprises an induction heating device. The induction heating device may comprise an inductor coil and a power source configured to provide a high-frequency oscillating current to the inductor coil. As used herein, high-frequency oscillating current refers to an oscillating current having a frequency between 500 kHz and 30 MHz. The heater may advantageously include a DC / AC inverter for converting DC current provided by a DC power source into alternating current. The inductor coil may be arranged to generate a high-frequency oscillating electromagnetic field upon receiving the high-frequency oscillating current from the power source. The inductor coil may be arranged to generate a high-frequency oscillating electromagnetic field within the device cavity. In some embodiments, the inductor coil may substantially surround the device cavity. The inductor coil may extend at least partially along the length of the device cavity.

[0338] The heater may include an induction heating element. The induction heating element may be a susceptor element. As used herein, the term "susceptor element" refers to an element comprising a material capable of converting electromagnetic energy into heat. When the susceptor element is placed in an alternating electromagnetic field, the susceptor is heated. Heating the susceptor element may result in at least one of hysteresis losses and eddy currents being induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material.

[0339] The susceptor element may be positioned such that, when an aerosol-generating article is received within the cavity of the aerosol-generating device, the oscillating electromagnetic field generated by the inductor coil induces current flow within the susceptor element, heating the susceptor element. In these embodiments, the aerosol-generating device is preferably capable of generating a fluctuating electromagnetic field having a magnetic field strength (H-field strength) of 1 to 5 kiloamperes per meter (kA / m), preferably 2 to 3 kA / m, e.g., about 2.5 kA / m. Electrically operated aerosol generators are preferably capable of generating a fluctuating electromagnetic field having a frequency of 1 to 30 MHz, e.g., 1 to 10 MHz, e.g., 5 to 7 MHz.

[0340] In these embodiments, the susceptor element is preferably positioned in contact with the aerosol-forming substrate. In some embodiments, the susceptor element is positioned within the aerosol-generating device. In these embodiments, the susceptor element may be positioned within a cavity. The aerosol-generating device may include only one susceptor element. The aerosol-generating device may include multiple susceptor elements. In some embodiments, the susceptor element is preferably positioned to heat the outer surface of the aerosol-forming substrate.

[0341] The susceptor elements may comprise any suitable material. They may be formed from any material that can be inductively heated to a temperature sufficient to release volatile compounds from the aerosol-forming substrate. Suitable materials for the elongated susceptor elements include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Some susceptor elements comprise metal or carbon. Advantageously, the susceptor elements may comprise or consist of ferromagnetic materials, such as ferritic iron, ferromagnetic steel, or stainless steel, ferromagnetic alloys, ferromagnetic particles, and ferrites. Suitable susceptor elements may be or include aluminum. The susceptor elements preferably comprise more than about 5 percent, preferably more than about 20 percent, and more preferably more than about 50 percent or more than about 90 percent ferromagnetic or paramagnetic material. Some elongated susceptor elements may be heated to temperatures greater than about 250°C.

[0342] The susceptor element may include a non-metallic core having a metallic layer disposed thereon, for example, the susceptor element may include a ceramic core or a metallic track formed on the outer surface of the substrate.

[0343] In some embodiments, the aerosol generating device may comprise at least one resistive heating element and at least one inductive heating element, hi some embodiments, the aerosol generating device may comprise a combination of resistive and inductive heating elements.

[0344] The heater may be controlled, during use, to operate within a defined operating temperature range that is below the maximum operating temperature. An operating temperature range of about 150°C to about 300°C within the heating chamber (or device cavity) is preferred. The operating temperature range of the heater may be from about 150°C to about 250°C.

[0345] Preferably, the heater may have an operating temperature range of about 150° C. to about 200° C. More preferably, the heater may have an operating temperature range of about 180° C. to about 200° C. In particular, as described herein, it has been found that optimal and consistent aerosol delivery can be achieved when using an aerosol generating device having an external heater with an operating temperature range of about 180° C. to about 200° C. with an aerosol-generating article having a relatively low RTD (e.g., an RTD in the downstream section of less than 15 mmH2O).

[0346] In embodiments in which the aerosol-generating article includes a ventilation zone along the downstream section or hollow tubular element, the ventilation zone may be positioned so that it is exposed when the aerosol-generating article is received within the device cavity. Thus, the length of the device cavity or heating chamber may be less than the distance from the upstream end of the aerosol-generating article to the ventilation zone located along the downstream section. In other words, when the aerosol-generating article is received within the aerosol-generating device, the distance between the ventilation zone and the upstream end of the upstream element may be greater than the length of the heating chamber.

[0347] When the article is received within the device cavity, the ventilation zone may be located at least 0.5 mm (in the downstream direction of the article) from the mouth end (or mouth end face) of the device cavity or the device itself. When the article is received within the device cavity, the ventilation zone may be located at least 1 mm (in the downstream direction of the article) from the mouth end (or mouth end face) of the device cavity or the device itself. When the article is received within the device cavity, the ventilation zone may be located at least 2 mm (in the downstream direction of the article) from the mouth end (or mouth end face) of the device cavity or the device itself.

[0348] The ratio between the ventilation zone, the upstream end of the upstream element, and the length of the heating chamber is preferably from about 1.03 to about 1.13.

[0349] This positioning of the ventilation zone ensures that the ventilation zone is not blocked within the device cavity itself, while minimizing the risk of blockage by the user's lips or hands, as the ventilation zone is as far upstream from the downstream end of the article as is reasonably possible without being blocked within the device cavity.

[0350] The aerosol-generating device may include a power source. The power source may be a DC power source. In some embodiments, the power source is a battery. The power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery (e.g., lithium cobalt, lithium iron phosphate, or lithium polymer battery). However, in some embodiments, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a volume that allows for the storage of sufficient energy for one or more user operations, such as one or more aerosol-generating experiences. For example, the power source may have a volume sufficient to allow continuous heating of the aerosol-generating substrate for approximately six minutes, or a multiple of six minutes, corresponding to the typical time it takes to smoke a conventional cigarette. In another example, the power source may have a volume sufficient to allow for a predetermined number of puffs or discontinuous operation of the heater. [Example]

[0351] Below is provided a non-exhaustive list of non-limiting examples, any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0352] Example 1 An aerosol-generating article comprising: a rod of aerosol-generating substrate; and a downstream section disposed downstream of the rod of aerosol-generating substrate, the downstream section comprising at least one hollow tubular element. Example 2 10. The aerosol-generating article of claim 1, further comprising an upstream section disposed upstream of the rod of the aerosol-generating substrate, the upstream section comprising at least one upstream element. Example 3 3. The aerosol-generating article of example 2, wherein the upstream element has a length of between 2 millimeters and 8 millimeters. Example 4 4. The aerosol-generating article of example 2 or 3, wherein the upstream element is formed from a hollow tubular segment defining a longitudinal cavity that provides an unrestricted flow channel. Example 5 An aerosol-generating article as described in Example 4, wherein the longitudinal cavity of the hollow tubular segment has a diameter of at least 5 millimeters. Example 6 An aerosol-generating article as described in Example 4 or 5, wherein the hollow tubular segment has a wall thickness of less than 1 millimeter. Example 7 7. An aerosol-generating article according to any one of Examples 2 to 6, wherein the upstream element has a resistance to draw (RTD) of less than 2 millimeters of H2O. Example 8 An aerosol-generating article according to any one of Examples 2 to 7, wherein the upstream end of the upstream element defines the upstream end of the aerosol-generating article. Example 9 An aerosol-generating article according to any one of Examples 1 to 8, further comprising a ventilation zone. Example 10 10. The aerosol-generating article of Example 9, wherein the ventilation zone is located at a position along the hollow tubular element in the downstream section. Example 11 11. The aerosol-generating article of any one of Examples 9 and 10, wherein the ventilation zone is located at a distance of 26 millimeters to 33 millimeters from the upstream end of the article. Example 12 11. The aerosol-generating article of example 9 or 10, wherein the ventilation zone is located at a distance of 27 millimeters to 31 millimeters from the upstream end of the article. Example 13 13. An aerosol-generating article according to any one of Examples 9 to 12, wherein the ventilation zone is located at a distance of 12 millimeters to 20 millimeters from the downstream end of the article. Example 14 An aerosol-generating article according to any one of Examples 9 to 13, wherein the ventilation zone is located at least 10 millimeters downstream of the downstream end of the rod of the aerosol-generating substrate. Example 15 An aerosol-generating article according to any one of Examples 1 to 14, wherein the hollow tubular element in the downstream section has a length of between 17 millimeters and 25 millimeters. Example 16 An aerosol-generating article according to any one of Examples 1 to 15, wherein the hollow tubular element of the downstream section has an internal volume of at least 300 cubic meters. Example 17 An aerosol-generating article according to any one of Examples 1 to 16, wherein the rod of the aerosol-generating substrate has a length of 8 mm to 16 mm. Example 18 An aerosol-generating article according to any one of Examples 1 to 17, wherein the rod of the aerosol-generating substrate has a resistance to withdrawal (RTD) of 4 mmH2O to 10 mmH2O. Example 19 An aerosol-generating article according to any one of Examples 1 to 18, wherein the aerosol-generating substrate comprises shredded tobacco material. Example 20 20. The aerosol-generating article of Example 19, wherein the shredded tobacco material has an average density of between 150 milligrams per cubic centimeter and 500 milligrams per cubic centimeter. Example 21 21. The aerosol-generating article of any one of Examples 1 to 20, wherein the aerosol-generating substrate comprises one or more aerosol-forming bodies, and the content of the aerosol-forming bodies in the aerosol-generating substrate is 10 to 20 percent by weight on a dry weight basis. Example 22 20. The aerosol-generating article of example 19, wherein the aerosol former comprises one or more of glycerin and propylene glycol. Example 23 An aerosol-generating article according to any one of Examples 1 to 22, wherein the aerosol-generating substrate comprises tobacco cut filler. Example 24 An aerosol-generating article according to any one of Examples 1 to 23, wherein the downstream section further comprises a mouthpiece element. Example 25 An aerosol-generating article as described in Example 24, wherein the mouthpiece element comprises at least one mouthpiece filter segment formed from a fibrous filtration material. Example 26 26. An aerosol-generating article according to Example 24 or 25, wherein the length of the mouthpiece element is between 3 millimeters and 11 millimeters. Example 27 27. The aerosol-generating article of any one of Examples 24 to 26, wherein the mouthpiece element has a resistance to withdrawal (RTD) of 4 mmH2O to 11 mmH2O. Example 28 An aerosol-generating article according to any one of Examples 24 to 27, wherein the combined length of the hollow tubular element and the mouthpiece element in the downstream section is between 24 millimeters and 32 millimeters. Example 29 An aerosol-generating article according to any one of Examples 1 to 28, wherein the resistance to withdrawal (RTD) of the article is between 20 mmH2O and 22 mmH2O. Example 30 30. An aerosol-generating article according to any one of Examples 1 to 29, wherein the outer diameter of the article is substantially uniform along its length. Example 31 An aerosol-generating article according to any one of Examples 1 to 30, wherein the aerosol-generating article has a breathability level of between 10 percent and 30 percent. Example 32 32. An aerosol-generating article according to any one of Examples 1 to 31, wherein the aerosol-generating article has a breathability level of between 12 percent and 25 percent. Example 33 An aerosol generating system comprising an aerosol-generating article described in any one of Examples 1 to 32, and an aerosol generating device comprising a heating chamber for receiving the aerosol-generating article and at least a heating element installed around or near the heating chamber.

[0353] The invention will now be further described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0354] [Figure 1] FIG. 1 shows a schematic cross-sectional side view of an aerosol-generating article according to an embodiment of the present invention. [Figure 2] FIG. 2 shows a schematic cross-sectional side view of an aerosol-generating article according to an embodiment of the present invention. [Figure 3] FIG. 3 shows a schematic cross-sectional view of an aerosol generating system including an aerosol-generating article according to an embodiment of the present invention and an aerosol generating device. DETAILED DESCRIPTION OF THE INVENTION

[0355] 1 comprises a rod of aerosol-generating substrate 12 and a downstream section 14 located downstream of the rod of aerosol-generating substrate 12. The aerosol-generating article 10 thus extends from an upstream or distal end 16, which is substantially coincident with the upstream end of the rod 12, to a downstream or oral end 18, which is coincident with the downstream end of the downstream section 14. The downstream section 14 comprises a hollow tubular element 20 and a mouthpiece element 50.

[0356] The aerosol-generating article 10 has an overall length of about 45 mm and an outer diameter of about 7.2 mm.

[0357] The aerosol-generating substrate rod 12 comprises shredded tobacco material. The aerosol-generating substrate rod 12 comprises 150 milligrams of shredded tobacco material containing 13 to 16 weight percent glycerin. The density of the aerosol-generating substrate is approximately 300 milligrams per cubic centimeter. The aerosol-generating substrate rod 12 has an RTD of approximately 6 to 8 mmH2O. The aerosol-generating substrate rods 12 are individually wrapped in plug wrap (not shown).

[0358] The hollow tubular element 20 is located immediately downstream of the rod 12 of the aerosol-generating substrate, and the hollow tubular element 20 is longitudinally aligned with the rod 12. The upstream end of the hollow tubular element 20 abuts the downstream end of the rod 12 of the aerosol-generating substrate.

[0359] The hollow tubular element 20 defines the hollow section of the aerosol-generating article 10. The hollow tubular element does not contribute substantially to the overall RTD of the aerosol-generating article. More specifically, the RTD of the hollow tubular element 20 is about 0 mmH2O.

[0360] 2, the hollow tubular element 20 is provided in the form of a hollow cylindrical tube made of cardboard. The hollow tubular element 20 defines an interior cavity 22 that extends from the upstream end of the hollow tubular element 20 all the way to the downstream end of the hollow tubular element 20. The interior cavity 22 is substantially empty, and thus, substantially unrestricted airflow is permitted along the interior cavity 22. The hollow tubular element 20 does not substantially contribute to the overall RTD of the aerosol-generating article 10.

[0361] The hollow tubular element 20 has a length of about 21 millimeters, an outer diameter of about 7.2 millimeters, and an inner diameter of about 6.7 millimeters. The peripheral wall thickness of the hollow tubular element 20 is therefore about 0.25 millimeters.

[0362] The aerosol-generating article 10 includes a ventilation zone 30 located along the hollow tubular element 20. More specifically, the ventilation zone 30 is located approximately 16 millimeters from the downstream end 18 of the article 10. The ventilation zone 30 is located approximately 12 mm downstream from the downstream end of the aerosol-generating substrate rod 12. The ventilation zone 30 is located approximately 9 mm upstream from the upstream end of the mouthpiece element 50. The ventilation zone 30 includes a row of circumferential openings or perforations surrounding the hollow tubular element 20. The perforations in the ventilation zone 30 extend through the wall of the hollow tubular element 20 to allow fluid to enter the interior cavity 22 from outside the article 10. The aerosol-generating article 10 has a ventilation level of approximately 16 percent.

[0363] Above the aerosol-generating substrate rod 12 and downstream section 14 downstream of rod 12, the aerosol-generating article 100 comprises an upstream section 40 upstream of rod 12. The aerosol-generating article 10 thus extends from a distal end 16 that is substantially identical to the upstream end of the upstream section 40 to a mouth end 18 that is substantially identical to the downstream end of the downstream section 14.

[0364] The upstream section 40 comprises an upstream element 42 located immediately upstream of the aerosol-generating substrate rod 12, the upstream element 42 being longitudinally aligned with the rod 12. The downstream end of the upstream element 42 abuts the upstream end of the aerosol-generating substrate rod 12. The upstream element 42 is provided in the form of a hollow, cylindrical plug of cellulose acetate tow having a wall thickness of approximately 1 mm and defining an interior cavity 23. The upstream element 42 has a length of approximately 5 millimeters. The outer diameter of the upstream element 42 is approximately 7.1 mm. The inner diameter of the upstream element 42 is approximately 5.1 mm.

[0365] The mouthpiece element 50 extends from the downstream end of the hollow tubular element 20 to the downstream or mouth end of the aerosol-generating article 10. The mouthpiece element 50 has a length of approximately 7 mm. The outer diameter of the mouthpiece element 50 is approximately 7.2 mm. The mouthpiece element 50 comprises a low-density cellulose acetate filter segment. The RTD of the mouthpiece element 50 is approximately 8 millimeters HO. The mouthpiece elements 50 may be individually wrapped in plug wrap (not shown).

[0366] 1 and 2, article 10 includes an upstream wrapper 44 that surrounds upstream element 42, aerosol-generating substrate 12, and hollow tubular element 20. Ventilation zone 30 may also include a row of circumferential perforations disposed on upstream wrapper 44. The perforations in upstream wrapper 44 overlap with the perforations disposed on hollow tubular element 20. Thus, upstream wrapper 44 covers the perforations in ventilation zone 30 that are disposed on hollow tubular element 20.

[0367] The article 10 also includes a tipping wrapper 52 that surrounds the hollow tubular element 20 and the mouthpiece element 50. The tipping wrapper 52 covers the portion of the upstream wrapper 44 that overlies the hollow tubular element 20. In this manner, the tipping wrapper 52 effectively joins the mouthpiece element 50 to the remaining components of the article 10. The width of the tipping wrapper 52 is approximately 26 mm. Additionally, the ventilation zone 30 may include a row of circumferential perforations located on the tipping wrapper 52. The perforations in the tipping wrapper 52 overlap with the perforations located on the hollow tubular element 20 and the upstream wrapper 44. Thus, the tipping wrapper 52 covers the perforations in the ventilation zone 30 that are located on the hollow tubular element 20 and the upstream wrapper 44.

[0368] FIG. 3 shows an aerosol generation system 100 including an exemplary aerosol generating device 1 and an aerosol-generating article 10 equivalent to those shown in FIGS. 1 and 2. FIG. 3 shows a downstream mouth-end portion of the aerosol generating device 1, in which a device cavity is defined and in which the aerosol-generating article 10 can be received. The aerosol generating device 1 includes a housing (or body) 4 extending between a mouth-end 2 and a distal end (not shown). The housing 4 includes a peripheral wall 6. The peripheral wall 6 defines the device cavity for receiving the aerosol-generating article 10. The device cavity is defined by a closed distal end and an open mouth-end. The mouth-end of the device cavity is located at the mouth-end of the aerosol generating device 1. The aerosol-generating article 10 is configured to be received through the mouth-end of the device cavity and abut against the closed end of the device cavity.

[0369] An airflow channel 5 of the device is defined within a peripheral wall 6. The airflow channel 5 extends between an inlet 7 located at the mouth end of the aerosol-generating device 1 and a closed end of the device cavity. Air can enter the aerosol-generating substrate 12 through an opening (not shown) located at the closed end of the device cavity, ensuring fluid communication between the airflow channel 5 and the aerosol-generating substrate 12.

[0370] The aerosol-generating device 1 further comprises a heater (not shown) and a power supply (not shown) for supplying power to the heater. A controller (not shown) is also provided for controlling such a power supply to the heater. The heater is configured to controllably heat the aerosol-generating article 10 during use when the aerosol-generating article 10 is received within the device 1. The heater is preferably positioned to externally heat the aerosol-generating substrate 12 for optimal aerosol generation. The ventilation zone 30 is positioned such that the aerosol-generating article 10 is exposed to the ventilation zone 30 when received within the aerosol-generating device 1.

[0371] In the embodiment shown in Figure 3, the device cavity defined by the peripheral wall 6 has a length of 28 mm. When the article 10 is received within the device cavity, the upstream section 40, the rod 12 of the aerosol-generating substrate, and the upstream portion of the hollow tubular element 20 are received within the device cavity. This upstream portion of the hollow tubular element 20 has a length of 11 mm. Therefore, approximately 28 mm of the article 10 is received within the device 1, and approximately 17 mm of the article 10 is located outside the device 1. In other words, approximately 17 mm of the article 10 protrudes from the device 1 when the article 10 is received therein. The length PL of the article 10 protruding from the device 1 is shown in Figure 3.

[0372] As a result, ventilation zone 30 is advantageously located outside device 1 when article 10 is inserted into device 1. If the device cavity is 28 mm long, ventilation zone 30 will be located 1 mm downstream from mouth end 2 of device 1 when article 10 is received therein. For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like should be understood in all instances to be modified by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± 10 percent of A. Within this context, the number A may be considered to include values ​​that are within the typical standard error for the measurement of the property that the number A modifies. The number A, in some instances used in the appended claims, may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. An aerosol-generating article comprising: a rod of aerosol-generating substrate having a length of between 8 millimeters and 16 millimeters, the aerosol-generating substrate comprising shredded tobacco material having an average density of between 150 milligrams per cubic centimeter and 500 milligrams per cubic centimeter, the shredded tobacco material being in the form of cut filler or shredded sheets of homogenized tobacco material; a downstream section provided downstream of the rod of the aerosol-generating substrate, the downstream section comprising at least one hollow tubular element abutting the downstream end of the rod of the aerosol-generating substrate; an upstream element disposed upstream of the rod of aerosol-generating substrate and abutting an upstream end of the rod of aerosol-generating substrate, the upstream end of the upstream element defining an upstream end of the aerosol-generating article; a ventilation zone located along the hollow tubular element, the ventilation zone configured to introduce ambient air into the lumen of the hollow tubular element, and the distance between the ventilation zone and the upstream end of the upstream element is between 26 millimeters and 33 millimeters.

2. 2. The aerosol-generating article of claim 1, wherein the distance between the ventilation zone and the upstream end of the upstream element is between 27 millimeters and 31 millimeters.

3. 3. An aerosol-generating article according to claim 1, wherein the rod of aerosol-generating substrate has a length of from 10 millimetres to 14 millimetres.

4. 4. The aerosol-generating article of claim 1, wherein the shredded tobacco material has an average density of from 250 milligrams per cubic centimeter to 400 milligrams per cubic centimeter.

5. 5. The aerosol-generating article of claim 1, further comprising a mouthpiece element disposed at the downstream end of the aerosol-generating article, the mouthpiece element comprising at least one mouthpiece filter segment formed from a fibrous filtering material.

6. 6. The aerosol-generating article of claim 5, wherein the hollow tubular element abuts the upstream end of the mouthpiece element, and the combined length of the hollow tubular element and the mouthpiece element is between 24 millimeters and 32 millimeters.

7. 7. An aerosol-generating article according to any one of claims 1 to 6, wherein the upstream element comprises a hollow tubular segment having a central longitudinal cavity therethrough.

8. 8. An aerosol-generating article according to any one of claims 1 to 7, wherein the upstream element has a length of between 3 millimetres and 7 millimetres.

9. 9. An aerosol-generating article according to claim 1, wherein the rod of the aerosol-generating substrate has an RTD of 4 mm WG to 10 mm WG.

10. 10. An aerosol-generating article according to any preceding claim, wherein the hollow tubular element has an RTD of between 1 mmWG and 5 mmWG.

11. 11. An aerosol-generating article according to any preceding claim, wherein the upstream element has an RTD of between 0.5 mm WG and 3 mm WG.

12. 12. The aerosol-generating article according to any one of claims 1 to 11, having a total RTD of between 17 mmWG and 23 mmWG.

13. 13. The aerosol-generating article according to claim 1, wherein the aerosol-generating substrate comprises one or more aerosol formers, and the content of the aerosol formers in the aerosol-generating substrate is at least 10 percent by weight on a dry weight basis.

14. 14. The aerosol-generating article of claim 13, wherein the aerosol-forming substance is present in an amount of at least 12 percent by weight on a dry weight basis.

15. 14. The aerosol-generating article according to claim 13, wherein the aerosol-forming substance is present in an amount of 20 weight percent or less on a dry weight basis in the aerosol-generating substrate.

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