WO2024180177A1

WO2024180177A1 - Aerosol-generating article having hollow tubular element

Info

Publication number: WO2024180177A1
Application number: PCT/EP2024/055224
Authority: WO
Inventors: Gaëtan Antony COUDERC; Alen Kadiric
Original assignee: Philip Morris Products S.A.
Priority date: 2023-03-01
Filing date: 2024-02-29
Publication date: 2024-09-06

Abstract

An aerosol-generating article (10) for producing an inhalable aerosol upon heating, the aerosol-generating article (10) comprising: a rod (12) of aerosol-generating substrate; a support element (22) downstream of the rod of aerosol-generating substrate (12), the support element (22) comprising a first hollow tubular element (26) having an internal diameter D1 and defining a longitudinal cavity (28) providing an unrestricted flow channel; and an aerosol-cooling element (24) downstream of the support element (22), the aerosol-cooling element (24) comprising a second hollow tubular element (34) having an internal diameter D2 of at least 6 millimetres, and defining a longitudinal cavity (36) providing an unrestricted flow channel. A ratio between the internal diameter D2 of the second hollow tubular element (34) and the internal diameter D1 of the first hollow tubular element (26) is at least 1.8.

Description

AEROSOL-GENERATING ARTICLE HAVING HOLLOW TUBULAR ELEMENT

The present invention relates to an aerosol-generating article comprising an aerosolgenerating substrate and adapted to produce an inhalable aerosol upon heating.

Aerosol-generating articles in which an aerosol-generating substrate, such as a tobaccocontaining substrate, is heated rather than combusted, are known in the art. Typically, in such heated smoking articles an aerosol is generated by the transfer of heat from a heat source to a physically separate 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 air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosolgenerating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosol-generating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosol-generating substrate. Use of an aerosol-generating article in combination with an external heating system is also known. For example, WO 2020/1 15151 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. As an alternative, inductively heatable aerosol-generating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosol-generating substrate have been proposed by WO 2015/176898.

Aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted present a number of challenges that were not encountered with conventional smoking articles. First of all, tobacco-containing substrates are typically heated to significantly lower temperatures compared with the temperatures reached by the combustion front in a conventional cigarette. This may have an impact on nicotine release from the tobacco-containing substrate and nicotine delivery to the consumer. At the same time, if the heating temperature is increased in an attempt to boost nicotine delivery, then the aerosol generated typically needs to be cooled to a greater extent and more rapidly before it reaches the consumer. However, technical solutions that were commonly used for cooling the mainstream smoke in conventional smoking articles, such as the provision of a high filtration efficiency segment at the mouth end of a cigarette, may have undesirable effects in an aerosol-generating article wherein a tobacco-containing substrate is heated rather than combusted, as they may reduce nicotine delivery. Accordingly, it would be desirable to provide novel aerosol-generating articles that can consistently ensure a satisfactory aerosol delivery to the consumer.

In addition, a need is generally felt for aerosol-generating articles that are easy to use and have improved practicality. For example, it would be desirable to provide an aerosol-generating article that can be easily inserted into a heating cavity of the aerosol-generating device, and that at the same time can be held securely within the heating cavity such that it does not slip out during use.

It would be further desirable to provide an aerosol-generating article that can be produced using more sustainable materials, in order to minimise the environmental impact of the used articles.

The present disclosure relates to an aerosol-generating article. The aerosol-generating article may comprise a rod of aerosol-generating substrate. The aerosol-generating article may further comprise a support element downstream of the rod of aerosol-generating substrate. The support element may comprise a first hollow tubular element having an internal diameter D1 and defining a longitudinal cavity providing an unrestricted flow channel. The aerosol-generating article may further comprise an aerosol-cooling element downstream of the support element. The aerosol-cooling element may comprise a second hollow tubular element having an internal diameter D2 of at least 6 millimetres and defining a longitudinal cavity providing an unrestricted flow channel. A ratio between the internal diameter D2 of the second hollow tubular element and the internal diameter D1 of the first hollow tubular element may be at least 1 .8.

According to the invention there is provided an aerosol-generating article for producing an inhalable aerosol upon heating, the aerosol-generating article comprising: a rod of aerosolgenerating substrate; a support element downstream of the rod of aerosol-generating substrate, the support element comprising a first hollow tubular element having an internal diameter D1 and defining a longitudinal cavity providing an unrestricted flow channel; and an aerosol-cooling element downstream of the support element, the aerosol-cooling element comprising a second hollow tubular element having an internal diameter D2 of at least 6 millimetres, and defining a longitudinal cavity providing an unrestricted flow channel. According to the present invention, a ratio between the internal diameter D2 of the second hollow tubular element and the internal diameter D1 of the first hollow tubular element is at least 1 .8.

The term “aerosol-generating article” is used herein to denote an article comprising an aerosol-generating substrate which is heated to produce and deliver an inhalable aerosol to a consumer. As used herein, the term “aerosol-generating substrate” denotes a substrate capable of releasing volatile compounds upon heating to generate an aerosol.

As used herein, the term “aerosol-generating device” refers to a device comprising a heater element that interacts with the aerosol-generating substrate of the aerosol-generating article to generate an aerosol. As used herein with reference to the present invention, the term “rod” is used to denote a generally elongate element, preferably a cylindrical element of substantially circular, oval or elliptical cross-section.

As used herein, the term “longitudinal” refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream and downstream ends of the aerosol-generating article. As used herein, the terms “upstream” and “downstream” describe the relative positions of elements, or portions of elements, of the aerosolgenerating article in relation to the direction in which the aerosol is transported through the aerosol-generating article during use.

During use, air is drawn through the aerosol-generating article in the longitudinal direction. The term “transverse” refers to the direction that is perpendicular to the longitudinal axis. Any reference to the “cross-section” of the aerosol-generating article or a component of the aerosolgenerating article refers to the transverse cross-section unless stated otherwise.

The term “length” denotes the dimension of a component of the aerosol-generating article in the longitudinal direction. For example, it may be used to denote the dimension of the rod or of the downstream section in the longitudinal direction.

As used herein, the term "hollow tubular element" denotes a generally elongate element defining a lumen or airflow passage along a longitudinal axis thereof. The “internal diameter” of the hollow tubular element corresponds to the diameter of the airflow passage.

In the context of the present invention, each hollow tubular element provides an unrestricted flow channel. This means that the hollow tubular element provides a negligible level of resistance to draw (RTD). The term “negligible level of RTD” is used to describe an RTD of less than 1 millimetres H2O per 10 millimetres of length of the hollow tubular element, preferably less than 0.4 millimetres H2O per 10 millimetres of length of the hollow tubular element, more preferably less than 0.1 millimetres H2O per 10 millimetres of length of the hollow tubular element.

Unless otherwise specified, the resistance to draw (RTD) of a component or the aerosolgenerating article is measured in accordance with ISO 6565-2015. The RTD refers the pressure required to force air through the full length of a component. The terms “pressure drop” or “draw resistance” of a component or article may also refer to the “resistance to draw”. Such terms generally refer to the measurements in accordance with ISO 6565-2015 are normally carried out at under test at a volumetric flow rate of 17.5 millilitres per second at the output or downstream end of the measured component at a temperature of 22 degrees Celsius, a pressure of 101 kPa (about 760 Torr) and a relative humidity of 60%. Conditions for smoking and smoking machine specifications are set out in ISO Standard 3308 (ISO 3308:2000). Atmosphere for conditioning and testing are set out in ISO Standard 3402 (ISO 3402:1999).

The present invention relates to an aerosol-generating article having a novel arrangement of hollow tubular elements downstream of the rod of aerosol-generating substrate. In particular, the aerosol-generating article of the present invention includes an aerosol-cooling element formed of a hollow tubular element (the second hollow tubular element) having a relatively high internal diameter. This is combined with an upstream support element, also formed of a hollow tubular element (the first hollow tubular element) which has an internal diameter that is significantly smaller than the internal diameter of the second hollow tubular element of the aerosol-cooling element. This difference in the internal size of the first and second hollow tubular elements is reflected by the relatively high ratio of the internal diameter D2 of the second hollow tubular element to the internal diameter D1 of the first hollow tubular element, which is defined as at least 1.8.

The relatively large internal diameter of the second hollow tubular element of the aerosolcooling element means that the aerosol-cooling element provides a cooling chamber with an increased volume. This provides enhanced cooling and nucleation of the aerosol particles generated from the substrate upon heating so that the aerosol delivery from the aerosolgenerating article can be optimised.

In order to provide a relatively large internal diameter in the second hollow tubular element, the wall thickness of the second hollow tubular element will typically be relatively thin. An increase in the internal diameter also increases the internal surface area of the aerosol-cooling element. Both of these factors provide improved transfer of heat from the inside to the outside of the aerosol-cooling element, thereby improving the efficiency of cooling within the chamber. The specific construction of the aerosol-cooling element is therefore able to provide an improved cooling function.

The provision of an aerosol-cooling element with a relatively thin wall thickness also enables it to be formed from a potentially wider range of materials. In particular, the aerosol-cooling element may be formed from paper or cardboard, both of which are lighter and more sustainable than more conventional materials used in aerosol-generating articles, such as cellulose acetate.

The upstream support element is formed of a hollow tubular element having a lower internal diameter and typically therefore a larger wall thickness. The support element is therefore still well adapted to perform its desired function of providing support and stability within the aerosolgenerating article, downstream of the rod of aerosol-generating substrate.

The defined ratio of internal diameters of the hollow tubular elements forming the support element and aerosol-cooling element means that the internal diameter of the aerosol-cooling element is significantly larger than the internal diameter of the support element. This difference between the internal diameters (and therefore also the transverse cross-sectional areas of the respective flow channels) achieves a controlled expansion of the aerosol, which decreases the speed of the aerosol as it passes from the support element to the aerosol-cooling element. This in turn increases the amount of time that the aerosol spends within the aerosol-cooling element, so that there is further optimisation of the cooling and nucleation of the aerosol particles, as described above.

As defined above, in the aerosol-generating articles of the present invention, the aerosolcooling element is provided downstream of the support element. Preferably, the upstream end of the aerosol-cooling element abuts the downstream end of the support element. The downstream end of the aerosol-cooling element may coincide with the downstream end of the aerosol-generating article. Alternatively, the aerosol-generating article may comprise one or more further components downstream of the aerosol-cooling element, as described below.

The aerosol-cooling element comprises the second hollow tubular element. Preferably, the aerosol-cooling element consists of the second hollow tubular element only. Alternatively, the aerosol-cooling element may comprise one or more additional cooling elements.

The second hollow tubular element of the aerosol-cooling element has an internal diameter of at least 6 millimetres, more preferably at least 6.1 millimetres, more preferably at least 6.2 millimetres, more preferably at least 6.3 millimetres, more preferably at least 6.4 millimetres, more preferably at least 6.5 millimetres, more preferably at least 6.6 millimetres, more preferably at least 6.7 millimetres, more preferably at least 6.8 millimetres.

The internal diameter of the second hollow tubular element is preferably less than 7.3 millimetres, more preferably less than 7.25 millimetres, more preferably less than 7.2 millimetres, more preferably less than 7.15, more preferably less than 7.1 , more preferably less than 7 millimetres.

The internal diameter of the second hollow tubular element may therefore be between 6 millimetres and 7.3 millimetres, or between 6.1 millimetres and 7.25 millimetres, or between 6.2 millimetres and 7.2 millimetres, or between 6.3 millimetres and 7.2 millimetres, or between 6.4 millimetres and 7.15 millimetres, or between 6.5 millimetres and 7.15 millimetres, or between 6.6 millimetres and 7.1 millimetres, or between 6.7 millimetres and 7.1 millimetres, or between 6.8 millimetres and 7 millimetres.

Preferably, the second hollow tubular element has a constant internal diameter along its full length. However, the internal diameter of the second hollow tubular element may vary along its length. In such cases, the “internal diameter” as referred to herein should be considered as the average internal diameter over the length of the hollow tubular element.

The external diameter of the second hollow tubular element is preferably between 5 millimetres and 12 millimetres, more preferably between 6 millimetres and 10 millimetres, more preferably between 7 millimetres and 8 millimetres, more preferably between 7 millimetres and 7.5 millimetres. In some embodiments, the external diameter of the second hollow tubular element may be less than 7 millimetres, for example, between 5 millimetres and 7 millimetres, or between 6 millimetres and 7 millimetres. The second hollow tubular element preferably has an external diameter that is approximately equal to the external diameter of the rod of aerosol-generating substrate and to the external diameter of the aerosol-generating article.

The ratio of the internal diameter of the second hollow tubular element to the external diameter of the second hollow tubular element is preferably at least 0.75, more preferably at least 0.8, more preferably at least 0.85, more preferably at least 0.9. The ratio of the internal diameter of the second hollow tubular element to the external diameter of the second hollow tubular element may be up to 0.98.

The cavity of the second hollow tubular element may have any cross-sectional shape. Preferably, the cavity of the second hollow tubular element has a circular or substantially circular cross-sectional shape.

The wall thickness of the second hollow tubular element is preferably less than 0.5 millimetres, more preferably less than 0.45 millimetres, more preferably less than 0.4 millimetres, more preferably less than 0.35 millimetres. The wall thickness is preferably at least 0.1 millimetres, more preferably at least 0.15 millimetres, more preferably at least 0.2 millimetres.

For example, the wall thickness of the second hollow tubular element may be between 0.1 millimetres and 0.5 millimetres, or between 0.15 millimetres and 0.45 millimetres, or between 0.15 millimetres and 0.4 millimetres, or between 0.2 millimetres and 0.4 millimetres, or between 0.2 millimetres and 0.35 millimetres. As described above, the second hollow tubular element therefore has a relatively thin wall.

The second hollow tubular element is preferably formed of a paper based material, such as paper or cardboard material. Preferably, the second hollow tubular element is a paper tube formed of one or more paper layers. More preferably, the second hollow tubular element is a paper tube formed of a plurality of overlapping paper layers.

The second hollow tubular element preferably comprises at least 2 overlapping paper layers, more preferably at least 3 overlapping paper layers. The second hollow tubular element preferably comprises up to 10 overlapping papers layers, more preferably up to 5 overlapping paper layers. For example, the second hollow tubular element may comprise between 2 and 10 overlapping paper layers, or between 3 and 5 overlapping paper layers. The paper layers may be formed from the same paper material or a different paper material.

Each paper layer will typically extend around the second hollow tubular element at least once and preferably, each paper layer extends around the second hollow tubular element a plurality of times to build up the structure of the wall and achieve the desired wall thickness.

Preferably, the plurality of overlapping paper layers are helically wound about the longitudinal axis of the second hollow tubular element. This provides a spiral wound structure that is similar to that the layered structure of conventional paper straws. Hollow tubular elements incorporating a helical arrangement of layers for use in the present invention can be manufactured using existing straw making apparatus, such as the Hauni Straw Maker (HSM) from Hauni Maschinenbau GmbH.

The use of a spiral wound structure provides optimal structural strength to the second hollow tubular element, with increased mechanical strength in all directions compared to a similar structure with simple longitudinal wrapping.

The individual paper layers of the paper tube preferably each have a thickness of between 30 microns and 200 microns, more preferably between 45 microns and 150 microns, more preferably between 45 microns and 135 microns, more preferably between 75 microns and 125 microns.

The individual paper layers forming the paper tube may have the same thickness as each other. Alternatively, the individual paper layers forming the paper tube may have a different thickness to each other. For example, the paper tube may be formed of a plurality of paper layers each having a thickness within the defined ranges above, but wherein the thickness of the paper layers decreases going from the inner layer to the outer layer. Such an arrangement may be beneficial for the manufacturing process, as thicker paper layers require more strength to bend them into shape and it is easier to apply a greater strength to the inner layer or layers during manufacturing, for example, by wrapping the layer around a mandrel.

For example, the paper tube forming the second hollow tubular element may comprise one or more layers of a first paper material and one or more layers of a second paper material, wherein the thickness of the second paper material is greater than the thickness of the first paper material. The thickness of the second paper material may be at least 25 microns greater than the thickness of the first paper material, or at least 30 microns greater, or at least 40 microns greater.

The individual paper layers of the paper tube preferably each have a grammage of between 25 grams per square metre (gsm) and 150 gsm, or between 30 gsm and 130gsm, or between 35 gsm and 120 gsm.

The individual paper layers forming the paper tube may have the same grammage as each other. Alternatively, the individual paper layers forming the paper tube may have a different grammage to each other. For example, the paper tube may be formed of a plurality of paper layers each having a grammage within the defined ranges above, but wherein the grammage of the paper layers decreases going from the inner layer to the outer layer.

For example, the paper tube forming the second hollow tubular element may comprise one or more layers of a first paper material and one or more layers of a second paper material, wherein the grammage of the second paper material is greater than the grammage of the first paper material. The grammage of the second paper material may be at least 25 gsm greater than the thickness of the first paper material, or at least 30 gsm greater, or at least 40 gsm greater. The paper tube may be formed of paper layers having the same composition as each other. Alternatively, the paper tube may be formed of paper layers having a different composition to each other.

Preferably, the paper tube comprises at least one hydrophobic paper layer. The hydrophobic paper layer is preferably provided as the innermost layer of the paper tube, such that it provides the inner surface of the paper tube.

The term “hydrophobic” refers to a surface exhibiting water repelling properties. One useful way to determine this is to measure the water contact angle. The “water contact angle” is the angle, conventionally measured through the liquid, where a liquid/vapour interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via the Young equation. Hydrophobicity or water contact angle may be determined by utilizing TAPPI T558 test method and the result is presented as an interfacial contact angle and reported in “degrees” and can range from near zero to near 180 degrees.

In preferred embodiments, the hydrophobic paper layer is one including a paper layer having a water contact angle of about 30 degrees or greater, and preferably about 35 degrees or greater, or about 40 degrees or greater, or about 45 degrees or greater.

By way of example, the hydrophobic paper layer may comprise PVOH (polyvinyl alcohol), silicon or a wax such as a paraffin wax. The hydrophobic paper layer may have a hydrophobic coating layer of one of these material applied to the surface thereof, or the surface of the paper layer may have undergone a surface treatment from one of these materials in order to provide hydrophobicity.

The provision of a hydrophobic layer at the inside of the paper tube prevents the moisture from the aerosol penetrating the paper tube, so that the structural rigidity of the aerosol-cooling element can be retained during use. It may also advantageously reduce the friction with the surface of the manufacturing apparatus, such as a mandrel, during manufacturing.

The aerosol-cooling element may have a length of between 5 millimetres and 15 millimetres. Preferably, the aerosol-cooling element has a length of at least about 6 millimetres, more preferably at least about 7 millimetres. Preferably, the aerosol-cooling element has a length of less than about 12 millimetres, more preferably less than about 10 millimetres.

In some embodiments, the aerosol-cooling element has a length from about 5 millimetres to about 15 millimetres, preferably from about 6 millimetres to about 15 millimetres, more preferably from about 7 millimetres to about 15 millimetres. In other embodiments, the aerosolcooling element has a length from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In further embodiments, the aerosol-cooling element has a length from about 5 millimetres to about 10 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres. In particularly preferred embodiments of the invention, the aerosol-cooling element has a length of less than 10 millimetres. For example, in one particularly preferred embodiment, the aerosol-cooling element has a length of 8 millimetres or 9 millimetres. In such embodiments, the aerosol-cooling element therefore has a relatively short length compared to the aerosol-cooling elements of prior art aerosol-generating articles. A reduction in the length of the aerosol-cooling element is possible due to the optimised effectiveness of the hollow tubular element forming the aerosol-cooling element in the cooling and nucleation of the aerosol.

In preferred embodiments in which the aerosol-cooling element consists of the second hollow tubular element, the length of the second hollow tubular element is within the ranges defined above.

For example, in some embodiments, the second hollow tubular element has a length from about 5 millimetres to about 15 millimetres, preferably from about 6 millimetres to about 15 millimetres, more preferably from about 7 millimetres to about 15 millimetres. In other embodiments, the second hollow tubular element has a length from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In further embodiments, the second hollow tubular element has a length from about 5 millimetres to about 10 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres. In particularly preferred embodiments of the invention, the second hollow tubular element has a length of less than 10 millimetres. For example, in one particularly preferred embodiment, the second hollow tubular element has a length of 8 millimetres or 9 millimetres.

Preferably, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article substrate is at least 0.13, more preferably at least 0.14, even more preferably at least 0.15. A ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article substrate is preferably less than 0.3, more preferably less than 0.25, even more preferably less than 0.20.

In some embodiments, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is preferably from 0.13 to 0.3, more preferably from 0.14 to 0.3, even more preferably from 0.15 to 0.3. In other embodiments, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is preferably from 0.13 to 0.25, more preferably from 0.14 to 0.25, even more preferably from 0.15 to 0.25. In further embodiments, a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article is preferably from 0.13 to 0.2, more preferably from 0.14 to 0.2, even more preferably from 0.15 to 0.2. In a particularly preferred embodiment, a ratio between the length of the aerosol-cooling element and the overall length of the aerosolgenerating article is about 0.18. The second hollow tubular element may have an internal volume of between 150 cubic millimetres and 450 cubic millimetres. Preferably, the second hollow tubular element has an internal volume of at least about 200 cubic millimetres, more preferably at least about 250 cubic millimetres. Preferably, the second hollow tubular element has an internal volume of less than about 400 cubic millimetres, more preferably less than about 350 cubic millimetres.

In some embodiments, the second hollow tubular element has an internal volume from about 150 cubic millimetres to about 450 cubic millimetres, preferably from about 200 cubic millimetres to about 450 cubic millimetres, more preferably from about 250 cubic millimetres to about 450 cubic millimetres. In other embodiments, the second hollow tubular element has an internal volume from about 150 cubic millimetres to about 400 cubic millimetres, preferably from about 200 cubic millimetres to about 400 cubic millimetres , more preferably from about 250 cubic millimetres to about 400 cubic millimetres. In further embodiments, the second hollow tubular element has an internal volume from about 150 cubic millimetres to about 350 cubic millimetres, preferably from about 200 cubic millimetres to about 350 cubic millimetres , more preferably from about 250 cubic millimetres to about 350 cubic millimetres.

Preferably, the aerosol-cooling element further comprises a ventilation zone at a position along the second hollow tubular element. The ventilation zone extends through the wall of the hollow tubular element such that fluid communication is established between the flow channel internally defined by the second hollow tubular element and the outer environment. The ventilation zone comprises a plurality of perforations through the wall of the second hollow tubular element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. Preferably, each circumferential row of perforations comprises from 8 to 30 perforations.

The aerosol-generating article according to the present invention may have a ventilation level of at least 10 percent, preferably at least 15 percent, more preferably at least 20 percent, more preferably at least 25 percent, more preferably at least 30 percent. The ventilation level may be up to 60 percent, preferably up to 50 percent, more preferably up to 45 percent, more preferably up to 40 percent. For example, the ventilation level may be between 10 percent and 60 percent, or between 15 percent and 50 percent, or between 20 percent and 45 percent, or between 25 percent and 45 percent, or between 30 percent and 40 percent. In particularly preferred embodiments, the aerosol-generating article has a ventilation level of about 35 percent.

The term “ventilation level” is used throughout the present specification to denote a volume ratio between of the airflow admitted into the aerosol-generating article via the ventilation zone (ventilation airflow) and the sum of the aerosol airflow and the ventilation airflow. The greater the ventilation level, the higher the dilution of the aerosol flow delivered to the consumer. The rapid cooling induced by the admission of external air into the second hollow tubular element via the ventilation zone can be favourably used to enhance nucleation and growth of aerosol droplets.

A distance between the ventilation zone and a downstream end of the rod of aerosolgenerating substrate is preferably at least 6 millimetres, more preferably at least 7 millimetres, more preferably at least 8 millimetres, more preferably at least 9 millimetres, more preferably at least 10 millimetres.

A distance between the ventilation zone and a downstream end of the rod of aerosolgenerating substrate is preferably less than 16 millimetres, more preferably less than 15 millimetres, more preferably less than 14 millimetres, more preferably less than 13 millimetres more preferably less than 12 millimetres.

For example, a distance between the ventilation zone and a downstream end of the rod of aerosol-generating substrate may be between 6 millimetres and 16 millimetres, or between 7 millimetres and 15 millimetres, or between 8 millimetres and 14 millimetres, or between 9 millimetres and 13 millimetres or between 10 millimetres and 12 millimetres.

Positioning the ventilation zone at a distance from a downstream end of the rod of aerosolgenerating substrate within the ranges described above has the benefit of generally ensuring that, during use, the ventilation zone is just outside of the heating device when the aerosol-generating article is inserted in the heating device. Additionally, it has been found that positioning the ventilation zone at a distance from a downstream end of the rod of aerosol-generating substrate within the ranges described above may advantageously enhance nucleation and aerosol formation and delivery.

A distance between the ventilation zone and a downstream end of the aerosol-generating article is preferably at least 10 millimetres, more preferably at least 12 millimetres, more preferably at least 14 millimetres, more preferably at least 16 millimetres.

A distance between the ventilation zone and a downstream end of the aerosol-generating article is preferably less than 24 millimetres, more preferably less than 22 millimetres, more preferably less than 21 millimetres, more preferably less than 20 millimetres.

For example, a distance between the ventilation zone and a downstream end of the aerosol-generating article may be between 10 millimetres and 24 millimetres, or between 12 millimetres and 22 millimetres, or between 14 millimetres and 21 millimetres, or between 16 millimetres and 20 millimetres. In particularly preferred embodiments, the distance between the ventilation zone and the downstream end of the aerosol-generating article is about 18 millimetres.

Positioning the ventilation zone at a distance from a downstream end of the aerosolgenerating article within the ranges described above has the benefit of generally ensuring that, during use, when the aerosol-generating article is partially received within the heating device, a portion of the aerosol-generating article extending outside of the heating device is long enough for the consumer to comfortably hold the article between their lips. At the same time, evidence suggests that a length of the portion of the aerosol-generating article extending outside of the heating device were greater, it may become easy to inadvertently and undesirably bend the aerosol-generating article, and this may impair aerosol delivery or in general the intended use of the aerosol-generating article.

Preferably, the aerosol-cooling element has a negligible level of RTD. For example, preferably, the aerosol-cooling element has an RTD of less than 2 millimetres H2O, more preferably less than 1.5 millimetres H2O, more preferably less than 1 millimetres H2O, more preferably less than 0.5 millimetres H₂O and most preferably about 0 millimetres H₂O.

As defined above, the aerosol-generating articles of the present invention comprise a support element downstream of the rod of aerosol-generating substrate. Preferably, the upstream end of the support element abuts the downstream end of the rod of aerosol-generating substrate. Preferably, the downstream end of the support element abuts the upstream end of the aerosolcooling element.

The support element comprises the first hollow tubular element. Preferably, the support element comprises the first hollow tubular element only.

The first hollow tubular element preferably has an internal diameter of less than 5.5 millimetres, more preferably less than 5 millimetres, more preferably less than 4.5 millimetres, more preferably less than 4 millimetres, more preferably less than 3.5 millimetres.

The internal diameter of the first hollow tubular element is preferably at least 1 .5 millimetres, more preferably at least 2 millimetres, more preferably at least 2.5 millimetres, more preferably at least 2.75 millimetres, more preferably at least 3 millimetres.

For example, the internal diameter of the first hollow tubular element may be between 1.5 millimetres and 5.5 millimetres, or between 2 millimetres and 5 millimetres, or between 2.5 millimetres and 4.5 millimetres, or between 2.75 millimetres and 4 millimetres, or between 3 millimetres and 3.5 millimetres.

As defined above, according to the present invention, a ratio between the internal diameter of the second hollow tubular element and the internal diameter of the first hollow tubular element is at least 1 .8. The internal diameter of the second hollow tubular element forming the aerosolcooling element is therefore at least 1.8 times the internal diameter of the first hollow tubular element forming the support element.

Preferably a ratio between the internal diameter of the second hollow tubular element and the internal diameter of the first hollow tubular element is at least 1 .85, more preferably at least 1 .9, more preferably at least 1 .95, more preferably at least 2, more preferably at least 2.05, more preferably at least 2.1. Preferably, a ratio between the internal diameter of the second hollow tubular element and the internal diameter of the first hollow tubular element is less than 2.75, more preferably less than 2.6, more preferably less than 2.5, more preferably less than 2.4. Preferably, the first hollow tubular element has a constant internal diameter along its full length. However, the internal diameter of the second hollow tubular element may vary along its length. In such cases, the “internal diameter” as referred to herein should be considered as the average internal diameter over the length of the hollow tubular element.

The external diameter of the first hollow tubular element is preferably between 5 millimetres and 12 millimetres, more preferably between 6 millimetres and 10 millimetres, more preferably between 7 millimetres and 8 millimetres, more preferably between 7 millimetres and 7.5 millimetres. In some embodiments, the external diameter of the first hollow tubular element may be less than 7 millimetres, for example, between 5 millimetres and 7 millimetres, or between 6 millimetres and 7 millimetres.

The fist hollow tubular element preferably has an external diameter that is approximately equal to the external diameter of the rod of aerosol-generating substrate and to the external diameter of the aerosol-generating article.

The ratio of the internal diameter of the first hollow tubular element to the external diameter of the first hollow tubular element is preferably at least 0.25, more preferably at least 0.3, more preferably at least 0.35, more preferably at least 0.4. The ratio of the internal diameter of the first hollow tubular element to the external diameter of the first hollow tubular element may be up to 0.80.

The cavity of the first hollow tubular element may have any cross-sectional shape. Preferably, the cavity of the first hollow tubular element has a circular or substantially circular cross-sectional shape.

The wall thickness of the first hollow tubular element is preferably at least 1 millimetre, more preferably at least 1.5 millimetres, more preferably at least 2 millimetres. The wall thickness is preferably less than 3.5 millimetres, more preferably less than 3 millimetres, more preferably less than 2.75 millimetres.

For example, the wall thickness of the first hollow tubular element may be between 1 millimetres and 3.5 millimetres, or between 1.5 millimetres and 3 millimetres, or between 2 millimetres and 2.75 millimetres.

The first hollow tubular element may be formed from any suitable material or combination of materials. For example, the first hollow tubular element may be formed from one or more materials selected from the group consisting of: cellulose acetate; polyhydroxyalkanoate (PHA) fibres; cardboard; crimped paper, such as crimped heat resistant paper or crimped parchment paper; and polymeric materials, such as low density polyethylene (LDPE). In a preferred embodiment, the first hollow tubular element is a hollow acetate tube formed from cellulose acetate.

The support element may have a length of between 5 millimetres and 15 millimetres. Preferably, the support element has a length of at least about 6 millimetres, more preferably at least about 7 millimetres. Preferably, the support element has a length of less than about 12 millimetres, more preferably less than about 10 millimetres.

In some embodiments, the support element has a length from about 5 millimetres to about 15 millimetres, preferably from about 6 millimetres to about 15 millimetres, more preferably from about 7 millimetres to about 15 millimetres. In other embodiments, the support element has a length from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In further embodiments, the support element has a length from about 5 millimetres to about 10 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres.

In preferred embodiments in which the support element consists of the first hollow tubular element, the length of the first hollow tubular element is within the ranges defined above.

For example, in some embodiments, the first hollow tubular element has a length from about 5 millimetres to about 15 millimetres, preferably from about 6 millimetres to about 15 millimetres, more preferably from about 7 millimetres to about 15 millimetres. In other embodiments, the first hollow tubular element has a length from about 5 millimetres to about 12 millimetres, preferably from about 6 millimetres to about 12 millimetres, more preferably from about 7 millimetres to about 12 millimetres. In further embodiments, the first hollow tubular element has a length from about 5 millimetres to about 10 millimetres, preferably from about 6 millimetres to about 10 millimetres, more preferably from about 7 millimetres to about 10 millimetres. In particularly preferred embodiments of the invention, the first hollow tubular element has a length of 8 millimetres or 9 millimetres.

Preferably, a ratio between the length of the support element and the overall length of the aerosol-generating article is at least 0.13, more preferably at least 0.14, even more preferably at least 0.15. A ratio between the length of the support element and the overall length of the aerosolgenerating article is preferably less than 0.3, more preferably less than 0.25, even more preferably less than 0.20.

In some embodiments, a ratio between the length of the support element and the overall length of the aerosol-generating article is preferably from 0.13 to 0.3, more preferably from 0.14 to 0.3, even more preferably from 0.15 to 0.3. In other embodiments, a ratio between the length of the support element and the overall length of the aerosol-generating article is preferably from 0.13 to 0.25, more preferably from 0.14 to 0.25, even more preferably from 0.15 to 0.25. In further embodiments, a ratio between the length of the support element and the overall length of the aerosol-generating article is preferably from 0.13 to 0.2, more preferably from 0.14 to 0.2, even more preferably from 0.15 to 0.2. In a particularly preferred embodiment, a ratio between the length of the support element and the overall length of the aerosol-generating article is 0.18. The first hollow tubular element may have an internal volume of between 10 cubic millimetres and 200 cubic millimetres. Preferably, the second hollow tubular element has an internal volume of at least about 20 cubic millimetres, more preferably at least about 50 cubic millimetres. Preferably, the second hollow tubular element has an internal volume of less than about 150 cubic millimetres, more preferably less than about 90 cubic millimetres.

In some embodiments, the first hollow tubular element has an internal volume of between about 10 cubic millimetres and about 200 cubic millimetres, preferably between about 20 cubic millimetres and about 200 cubic millimetres, more preferably between about 50 cubic millimetres and about 200 cubic millimetres. In other embodiments, the first hollow tubular element has an internal volume of between about 10 cubic millimetres and about 150 cubic millimetres, preferably between about 20 cubic millimetres and about 150 cubic millimetres, more preferably between about 50 cubic millimetres and about 150 cubic millimetres. In further embodiments, the first hollow tubular element has an internal volume of between about 10 cubic millimetres and about 90 cubic millimetres, preferably between about 20 cubic millimetres and about 90 cubic millimetres, more preferably between about 50 cubic millimetres and about 90 cubic millimetres.

Preferably, a ratio between the length of the aerosol-cooling element and the length of the support element is at least 0.8, more preferably at least 0.9, more preferably at least 1 , more preferably at least 1.1 , more preferably at least 1 .2, more preferably at least 1 .3, more preferably at least 1.4, more preferably at least 1.5. A ratio between the length of the aerosol-cooling element and the length of the support element may be up to 2.2, more preferably up to 2.1 , more preferably up to 2.

For example, in some embodiments, a ratio between the length of the aerosol-cooling element and the length of the support element may be between 0.8 and 1 . In these embodiments, the aerosol-cooling element has a length that is less than or equal to that of the support element. In other embodiments, a ratio between the length of the aerosol-cooling element and the length of the support element may be between 1.1 and 2.2, or between 1 .2 and 2.1 , or between 1 .3 and 2.1 , or between 1 .4 and 2, or between 1 .5 and 2.

Preferably, a ratio between the internal volume of the aerosol-cooling element and the internal volume of the support element is at least 1 , more preferably at least 1 .5, more preferably at least 2, more preferably at least 2.5, more preferably at least 3, more preferably at least 3.5. A ratio between the internal volume of the aerosol-cooling element and the internal volume of the support element may be up to 20, more preferably up to 17.5, more preferably up to 15, more preferably up to 12.5, more preferably up to 10, more preferably up to 7.5.

For example, in some embodiments, a ratio between the internal volume of the aerosolcooling element and the internal volume of the support element may be between 1 and 20, or between 1.5 and 17.5, or between 2 and 15, or between 2.5 and 12.5, or between 3 and 10, or between 3.5 and 7.5. Preferably, the support element has a negligible level of RTD. For example, preferably, the support element has an RTD of less than 2 millimetres H2O, more preferably less than 1 .5 millimetres H2O, more preferably less than 1 millimetres H2O, more preferably less than 0.5 millimetres H2O and most preferably about 0 millimetres H2O.

As defined above, the aerosol-generating article according to the present invention further comprises a rod of aerosol-generating substrate.

Preferably, the rod of aerosol-generating substrate has a length of at least 8 millimetres, more preferably a length of at least 9 millimetres, more preferably a length of at least 10 millimetres. Preferably, the length of the rod of aerosol-generating substrate is less than 16 millimetres, more preferably less than 15 millimetres, more preferably less than 14 millimetres. For example, the rod of aerosol-generating substrate may have a length of between 8 millimetres and 16 millimetres, or between 9 millimetres and 15 millimetres, or between 10 millimetres and 14 millimetres. In a particularly preferred embodiment, the rod of aerosol-generating substrate has a length of about 12 millimetres.

Preferably, the ratio between the length of the rod of aerosol-generating substrate and the overall length of the aerosol-generating article is at least 0.10, more preferably at least 0.15, more preferably at least 0.20, more preferably at least 0.25. Preferably, the ratio between the length of the rod of aerosol-generating substrate and the overall length of the aerosol-generating article is less than 0.50, more preferably less than 0.45, more preferably less than 0.40, more preferably less than 0.35. For example, the ratio between the length of the rod of aerosol-generating substrate and the overall length of the aerosol-generating article may be between 0.1 and 0.5, or between 0.15 and 0.45, or between 0.2 and 0.4, or between 0.25 and 0.35.

Preferably, the rod of aerosol-generating substrate has an external diameter that is approximately equal to the external diameter of the aerosol-generating article.

Preferably, the rod of aerosol-generating substrate has an external diameter of at least 5 millimetres, more preferably at least 6 millimetres, more preferably at least 7 millimetres. Prior to insertion of the aerosol-generating article into the aerosol-generating device, the rod of aerosolgenerating substrate preferably has an external diameter of less than 12 millimetres, more preferably less than 10 millimetres, more preferably less than 8 millimetres. For example, the external diameter may be between 5 millimetres and 12 millimetres, or between 6 millimetres and 10 millimetres, or between 7 millimetres and 8 millimetres. In a particularly preferred embodiment, the rod of aerosol-generating substrate has an external diameter of about 7.1 millimetres.

Preferably, the rod of aerosol-generating substrate has a substantially uniform crosssection along the length of the rod. Particularly preferably, the rod of aerosol-generating substrate has a substantially circular cross-section prior to insertion of the aerosol-generating article into the aerosol-generating device. The aerosol-generating substrate may be a solid aerosol-generating substrate. Suitable types of materials for use in the aerosol-generating substrate are described below and include, for example, tobacco cut filler, homogenised tobacco material such as cast leaf, aerosolgenerating films and gel compositions.

The aerosol-generating substrate preferably comprises an aerosol former. The aerosol former may be any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol. The aerosol former may be facilitating that the aerosol is substantially resistant to thermal degradation at temperatures typically applied during use of the aerosol-generating article. Suitable aerosol formers are for example: polyhydric alcohols such as, for example, triethylene glycol, 1 ,3-butanediol, propylene glycol and glycerine; esters of polyhydric alcohols such as, for example, glycerol mono-, di- or triacetate; aliphatic esters of mono-, di- or polycarboxylic acids such as, for example, dimethyl dodecanedioate and dimethyl tetradecanedioate; and combinations thereof.

Preferably, the aerosol former comprises one or more of glycerine and propylene glycol. The aerosol former may consist of glycerine or propylene glycol or of a combination of glycerine and propylene glycol.

In certain embodiments, the aerosol-generating substrate preferably comprises at least 5 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably at least 10 percent by weight on a dry weight basis, more preferably at least 15 percent by weight on a dry weight basis. In such embodiments, the aerosol-generating substrate preferably comprises no more than 30 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably no more than 25 percent by weight on a dry weight basis, more preferably no more than 20 percent by weight on a dry weight basis. For example, the aerosol former content of the aerosol-generating substrate may be between 5 percent and 30 percent by weight, or between 10 percent and 25 percent by weight, or between about 15 percent and about 20 percent by weight, on a dry weight basis. In such embodiments, the aerosol former content is therefore relatively low.

In other embodiments, the aerosol-generating substrate preferably comprises at least 40 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably at least 45 percent by weight on a dry weight basis, more preferably at least 50 percent by weight on a dry weight basis. In such embodiments, the aerosol-generating substrate preferably comprises no more than 80 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably no more than 75 percent by weight on a dry weight basis, more preferably no more than 70 percent by weight on a dry weight basis. For example, the aerosol former content of the aerosol-generating substrate may be between 40 percent and 80 percent by weight, or between 45 percent and 75 percent by weight, or between about 50 percent and about 70 percent by weight, on a dry weight basis. In such embodiments, the aerosol former content is therefore relatively high.

In some preferred embodiments, the aerosol-generating substrate comprises tobacco material. For example, the aerosol-generating substrate may comprise 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 a shredded sheet of homogenised tobacco material. Suitable homogenised tobacco materials for use in the present invention are described below.

Within the context of the present specification, the term “cut filler” is used to describe to a blend of shredded plant material, such as tobacco plant material, including, in particular, one or more of leaf lamina, processed stems and ribs, homogenised plant material.

The cut filler may also comprise other after-cut, filler tobacco or casing.

Preferably, the cut filler comprises at least 25 percent of plant leaf lamina, more preferably, at least 50 percent of plant leaf lamina, still more preferably at least 75 percent of plant leaf lamina and most preferably at least 90 percent of plant leaf lamina. Preferably, the plant material is one of tobacco, mint, tea and cloves. Most preferably, the plant material is tobacco. However, the invention is equally applicable to other plant material that has the ability to release substances upon the application of heat that can subsequently form an aerosol.

The cut filler suitable to be used with the present invention generally may resemble cut filler used for conventional smoking articles. The cut width of the cut filler preferably may be between 0.3 millimetres and 2.0 millimetres, or between 0.5 millimetres and 1.2 millimetres, or between 0.6 millimetres and 0.9 millimetres.

Preferably, the strands have a length of between about 10 millimetres and about 40 millimetres before the strands are collated to form the rod of aerosol-generating substrate.

In preferred embodiments, the weight of the cut filler is between 25 milligrams and 150 milligrams, preferably between 30 milligrams and 125 milligrams, more preferably between 40 milligrams and 100 milligrams. This amount of cut filler typically allows for sufficient material for the formation of an aerosol during the early puffs.

Preferably, the cut filler is soaked with the aerosol former. Soaking the cut filler can be done by spraying or by other suitable application methods. The aerosol former may be applied to the blend during preparation of the cut filler. For example, the aerosol former may be applied to the blend in the direct conditioning casing cylinder (DCCC). Conventional machinery can be used for applying an aerosol former to the cut filler. Suitable aerosol formers are set out above.

Preferably, the aerosol former in the cut filler comprises one or more of glycerol and propylene glycol. The aerosol former may consist of glycerol or propylene glycol or of a combination of glycerol and propylene glycol. In other preferred embodiments, the aerosol-generating substrate comprises homogenised plant material, preferably a homogenised tobacco material.

As used herein, the term “homogenised plant material” encompasses any plant material formed by the agglomeration of particles of plant. For example, sheets or webs of homogenised tobacco material for the aerosol-generating substrates of the present invention may be formed by agglomerating particles of tobacco material obtained by pulverising, grinding or comminuting plant material and optionally one or more of tobacco leaf lamina and tobacco leaf stems. The homogenised plant material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

The homogenised plant material can be provided in any suitable form.

In some embodiments, the homogenised plant material may be in the form of one or more sheets. As used herein with reference to the invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.

The homogenised plant material may be in the form of a plurality of pellets or granules.

The homogenised plant material may be in the form of a plurality of strands, strips or shreds. As used herein, the term “strand” describes an elongate element of material having a length that is substantially greater than the width and thickness thereof. The term “strand” should be considered to encompass strips, shreds and any other homogenised plant material having a similar form. The strands of homogenised plant material may be formed from a sheet of homogenised plant material, for example by cutting or shredding, or by other methods, for example, by an extrusion method.

The aerosol former content of the homogenised tobacco material is preferably within the ranges defined above for aerosol-generating substrate having a relatively low aerosol former content.

In other preferred embodiments, the aerosol-generating substrate is in the form of an aerosol-generating film comprising a cellulosic based film forming agent, nicotine and the aerosol former. The aerosol-generating film may further comprise a cellulose based strengthening agent. The aerosol-generating film may further comprise water, preferably 30 percent by weight of less of water.

As used herein, the term “film” is used to describe a solid laminar element having a thickness that is less than the width or length thereof. The film may be self-supporting. In other words, a film may have cohesion and mechanical properties such that the film, even if obtained by casting a film-forming formulation on a support surface, can be separated from the support surface. Alternatively, the film may be disposed on a support or sandwiched between other materials. This may enhance the mechanical stability of the film.

The aerosol former content of the aerosol-generating film is within the ranges defined above for aerosol-generating substrates having a relatively high aerosol former content. In the context of the present invention the term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film. Preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methyl cellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof. In particularly preferred embodiments, the cellulose based film-forming agent is HPMC.

The aerosol-generating film may have a cellulose based film-forming agent content of between 10 percent and 40 percent by weight, or between 15 percent and 35 percent by weight, or between 20 percent and 30 percent by weight, on a dry weight basis.

Preferably, the aerosol-generating film further comprises a cellulose based strengthening agent. Preferably, the cellulose based strengthening agent is selected from the group consisting of cellulose fibres, microcrystalline cellulose (MCC), cellulose powder, and combinations thereof.

The aerosol-generating film may have a cellulose based strengthening agent content of between 0.5 percent and 40 percent by weight on a dry weight basis, or between 5 percent and 30 percent by weight on a dry weight basis, or between 10 percent and 25 percent by weight on a dry weight basis.

The aerosol-generating film may further comprise a carboxymethyl cellulose, preferably sodium carboxymethyl cellulose. The aerosol-generating film may have a carboxymethyl cellulose content of between 1 percent and 15 percent by weight, or between 2 percent and 12 percent by weight, or between 4 percent and 10 percent by weight on a dry weight basis.

The aerosol-generating film preferably comprises nicotine. As used herein with reference to the invention, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt. In embodiments in which the aerosol-generating film comprises a nicotine base or a nicotine salt, the amounts of nicotine recited herein are the amount of free base nicotine or amount of protonated nicotine, respectively.

The aerosol-generating film may comprise natural nicotine or synthetic nicotine.

The aerosol-generating film may comprise one or more monoprotic nicotine salts. As used herein with reference to the invention, the term “monoprotic nicotine salt” is used to describe a nicotine salt of a monoprotic acid.

Preferably, the aerosol-generating film comprises between 0.5 percent and 10 percent by weight of nicotine, or between 1 percent and 8 percent by weight of nicotine, or between 2 percent and 6 percent by weight of nicotine, on a dry weight basis.

The aerosol-generating film may be a substantially tobacco-free aerosol-generating film.

In preferred embodiments, the aerosol-generating film comprises an acid. More preferably, the aerosol-generating film comprises one or more organic acids. Even more preferably, the aerosol-generating film comprises one or more carboxylic acids. In particularly preferred embodiments, the acid is lactic acid, benzoic acid, fumaric acid or levulinic acid.

Preferably, the aerosol-generating film comprises between 0.25 percent and 3.5 percent by weight of an acid, or between 0.5 percent and 3 percent by weight of an acid, or between 1 percent and 2.5 percent by weight of an acid, on a dry weight basis.

The aerosol-generating film may have a thickness from about 0.1 millimetres to about 1 millimetre, more preferably from about 0.1 millimetres to about 0.75 millimetres, even more preferably from about 0.1 millimetres to about 0.5 millimetres. In particularly preferred embodiments, a layer of the film-forming composition is formed that has a thickness from about 50 micrometres to 400 micrometres, more preferably from about 100 micrometres to 200 micrometres.

The aerosol-generating film may optionally be provided within the aerosol-generating substrate on a suitable carrier element.

In alternative embodiments of the invention, the aerosol-generating substrate may comprise a gel composition that includes nicotine, at least one gelling agent and the aerosol former. The gel composition is preferably substantially tobacco free.

The preferred weight ranges for nicotine in the gel composition are the same as those defined above in relation to aerosol-generating films.

The gel composition preferably comprises at least 50 percent by weight of aerosol former, more preferably at least 60 percent by weight, more preferably at least 70 percent by weight of aerosol former, on a dry weight basis. The gel composition may comprise up to 80 percent by weight of aerosol former. The aerosol former in the gel composition is preferably glycerol.

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

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

The term “hydrogen-bond crosslinking gelling agent” refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via hydrogen bonding. The hydrogen-bond crosslinking gelling agent may include one or more of a galactomannan, gelatin, agarose, or konjac gum, or agar. The hydrogen-bond crosslinking gelling agent may preferably include agar. The term “ionic crosslinking gelling agent” refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via ionic bonding. The ionic crosslinking gelling agent may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan or alginate. The ionic crosslinking gelling agent may preferably include low acyl gellan.

The gelling agent may include one or more biopolymers. The biopolymers may be formed of polysaccharides.

Biopolymers include, for example, gellan gums (native, low acyl gellan gum, high acyl gellan gums with low acyl gellan gum being preferred), xanthan gum, alginates (alginic acid), agar, guar gum, and the like. The composition may preferably include xanthan gum. The composition may include two biopolymers. The composition may include three biopolymers. The composition may include the two biopolymers in substantially equal weights. The composition may include the three biopolymers in substantially equal weights.

The gel composition may further include a viscosifying agent. The viscosifying agent combined with the hydrogen-bond crosslinking gelling agent and the ionic crosslinking gelling agent appears to surprisingly support the solid medium and maintain the gel composition even when the gel composition comprises a high level of glycerol.

The term “viscosifying agent” refers to a compound that, when added homogeneously into a 25°C, 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of 0.3 percent by weight., increases the viscosity without leading to the formation of a gel, the mixture staying or remaining fluid.

The gel composition preferably includes the viscosifying agent in a range from about 0.2 percent by weight to about 5 percent by weight, or from about 0.5 percent by weight to about 3 percent by weight, or from about 0.5 percent by weight to about 2 percent by weight, or from about 1 percent by weight to about 2 percent by weight.

The viscosifying agent may include one or more of xanthan gum, carboxymethyl-cellulose, microcrystalline cellulose, methyl cellulose, gum Arabic, guar gum, lambda carrageenan, or starch. The viscosifying agent may preferably include xanthan gum.

The gel composition may further include a divalent cation. Preferably the divalent cation includes calcium ions, such as calcium lactate in solution. Divalent cations (such as calcium ions) may assist in the gel formation of compositions that include gelling agents such as the ionic crosslinking gelling agent, for example. The ion effect may assist in the gel formation. The divalent cation may be present in the gel composition in a range from about 0.1 to about 1 percent by weight, or about 0.5 percent by weight t.

The gel composition may further include an acid. The acid may comprise a carboxylic acid, such as levulinic acid or lactic acid.

The gel composition preferably comprises some water. The gel composition is more stable when the composition comprises some water. Preferably the gel composition comprises between about 8 percent by weight to about 32 percent by weight water, or from about 15 percent by weight to about 25 percent by weight water, or from about 18 percent by weight to about 22 percent by weight water, or about 20 percent by weight water.

Preferably, where a gel composition is used, the aerosol-generating substrate comprises a porous medium loaded with the gel composition. The term “porous” is used herein to refer to a material that provides a plurality of pores or openings that allow the passage of air through the material.

In certain embodiments of the invention, the aerosol-generating article further comprises one or more elongate susceptor elements within the rod of aerosol-generating substrate. For example, one or more elongate susceptor elements may be arranged substantially longitudinally within the rod of aerosol-generating substrate and in thermal contact with the aerosol-generating substrate.

As used herein with reference to the present invention, the term “susceptor element” refers to a material that can convert electromagnetic energy into heat. When located within a fluctuating electromagnetic field, eddy currents induced in the susceptor element cause heating of the susceptor element. As the susceptor element is located in thermal contact with the aerosolgenerating substrate, the aerosol-generating substrate is heated by the susceptor element.

When used for describing the susceptor element, the term “elongate” means that the susceptor element has a length dimension that is greater than its width dimension or its thickness dimension, for example greater than twice its width dimension or its thickness dimension.

The susceptor element is arranged substantially longitudinally within the rod of aerosolgenerating substrate. This means that the length dimension of the elongate susceptor element is arranged to be approximately parallel to the longitudinal direction of the rod, for example within plus or minus 10 degrees of parallel to the longitudinal direction of the rod. In preferred embodiments, the elongate susceptor element may be positioned in a radially central position within the rod, and extends along the longitudinal axis of the rod.

The susceptor element is preferably in the form of a pin, rod, strip or blade.

The susceptor element preferably has a width from 1 millimetre to 5 millimetres.

The susceptor element may generally have a thickness from 0.01 millimetres to 2 millimetres, for example from 0.5 millimetres to 2 millimetres. In some embodiments, the susceptor element preferably has a thickness from 10 micrometres to 500 micrometres, more preferably from 10 micrometres to 100 micrometres.

Preferably, the elongate susceptor element has a length which is the same or shorter than the length of the aerosol-generating segment in which it is incorporated. Preferably, the elongate susceptor element has a same length as the aerosol-generating rod in which it is incorporated. The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-generating substrate. Preferred susceptor elements comprise a metal or carbon.

A preferred susceptor element may comprise or consist of a ferromagnetic material, for example a ferromagnetic alloy, ferritic iron, or a ferromagnetic steel or stainless steel. A suitable susceptor element may be, or comprise, aluminium.

Preferably, the rod of aerosol-generating substrate is circumscribed by a wrapper. The wrapper may be a paper wrapper or a non-paper wrapper.

Suitable paper wrappers for use in specific embodiments of the invention are known in the art and include, but are not limited to: cigarette papers; and filter plug wraps. Suitable non-paper wrappers for use in specific embodiments of the invention are known in the art and include, but are not limited to sheets of homogenised tobacco materials.

Aerosol-generating articles according to the present disclosure may further comprise 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.

The upstream element advantageously prevents direct physical contact with the upstream end of the rod of aerosol-generating substrate. Furthermore, the presence of an upstream element helps to prevent any loss of the substrate, which may be advantageous, for example, if the substrate contains particulate plant material.

Where the rod of aerosol-generating substrate comprises shredded tobacco, such as tobacco cut filler, the upstream section or element thereof may additionally help to prevent the loss of loose particles of tobacco from the upstream end of the article. This may be particularly important when the shredded tobacco has a relatively low density, for example.

An upstream element may be a porous plug element. Preferably, an upstream element has a porosity of at least 50 percent in the longitudinal direction of the aerosol-generating article. More preferably, an upstream element has a porosity of between 50 percent and 90 percent in the longitudinal direction. The porosity of an upstream element in the longitudinal direction is defined by the ratio of the cross-sectional area of material forming the upstream element and the internal cross-sectional area of the aerosol-generating article at the position of the upstream element.

An upstream element may be made of a porous material or may comprise a plurality of openings. This may, for example, be achieved through laser perforation. Preferably, the plurality of openings is distributed homogeneously over the cross-section of the upstream element. The porosity or permeability of an upstream element may advantageously be designed in order to provide an aerosol-generating article with a particular overall resistance to draw (RTD) without substantially impacting the filtration provided by other portions of the article.

An upstream element may be formed from a material that is impermeable to air. In such embodiments, the aerosol-generating article may be configured such that air flows into the rod of aerosol-generating substrate through suitable ventilation means provided in a wrapper.

The upstream element may be made of any material suitable for use in an aerosolgenerating article. The upstream element may, for example, be made of a same material as used for one of the other components of the aerosol-generating article, such as the mouthpiece, the cooling element or the support element. Suitable materials for forming the upstream element include filter materials, ceramic, polymer material, cellulose acetate, cardboard, zeolite or aerosolgenerating substrate. Preferably, the upstream element is formed from a plug of cellulose acetate.

Preferably, the upstream element is formed of a heat resistant material. For example, preferably the upstream element is formed of a material that resists temperatures of up to 350 degrees Celsius. This ensures that the upstream element is not adversely affected by the heating means for heating the aerosol-generating substrate.

In certain preferred embodiments, the upstream element is formed of a solid cylindrical plug element having a filled cross-section. Such a plug element may be referred to as a ‘plain’ element. The solid plug element may be porous but does not have a tubular form and therefore does not provide any longitudinal flow channel. The solid plug element preferably has a substantially uniform transverse cross section.

In such embodiments, the upstream element preferably has a resistance to draw (RTD) of less than 25 millimetres H2O, or less than 22 millimetres H2O, or less than 20 millimetres H2O. Preferably, in such embodiments, the upstream element has an RTD of at least 10 millimetres H2O, or at least 12 millimetres H2O, or at least 14 millimetres H2O, or at least 16 millimetres H2O. For example, the upstream element may have an RTD of between 10 millimetres H2O and 25 millimetres H2O, or between 12 millimetres H2O and 22 millimetres H2O, or between 14 millimetres H2O and 20 millimetres H2O, or between 16 millimetres H2O and 20 millimetres H2O.

In other embodiments, the upstream element is formed of a hollow tubular segment defining a longitudinal cavity providing an unrestricted flow channel. In such embodiments, the upstream element can provide protection for the aerosol-generating substrate, as described above, whilst having a minimal effect on the overall resistance to draw (RTD) and filtration properties of the article.

Preferably, the diameter of the longitudinal cavity of the hollow tubular segment forming an upstream element is at least about 4 millimetres, more preferably at least about 4.5 millimetres, more preferably at least about 5 millimetres and more preferably at least about 5.5 millimetres. Preferably, the diameter of the longitudinal cavity is maximised in order to minimise the RTD of the upstream section, or upstream element thereof. An internal diameter of the upstream element may be about 5.1 mm.

Preferably, the wall thickness of the hollow tubular segment is less than about 2 millimetres, more preferably less than about 1 .5 millimetres and more preferably less than about 1 .25 millimetres. The wall thickness of the hollow tubular segment defining an upstream element may about 1 mm.

In such embodiments, the upstream element preferably has an RTD of less than 10 millimetres H2O, more preferably less than 5 millimetres H2O, more preferably less than 2.5 millimetres H2O. Preferably, in such embodiments, the upstream element has an RTD of at least at least 0.1 millimetres H₂O, or at least about 0.25 millimetres H₂O or at least about 0.5 millimetres H2O. For example, the upstream element may have an RTD of between 0.1 millimetres H2O and 10 millimetres H2O, or between 0.25 millimetres H2O and 5 millimetres H2O, or between 0.5 millimetres H2O and 2.5 millimetres H2O.

Preferably, the upstream element has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. Preferably, the external diameter of the upstream element prior to any compression is between 6 millimetres and 8 millimetres, more preferably between 7 millimetres and 7.5 millimetres. Preferably, the upstream element has an external diameter that is about 7.1 mm.

Preferably, the upstream element has a length of between 2 millimetres and 8 millimetres, more preferably between 3 millimetres and 7 millimetres, more preferably between 4 millimetres and 6 millimetres. In a particularly preferred embodiment, the upstream element has a length of about 5 millimetres.

The upstream element is preferably circumscribed by a wrapper, such as a plug wrap. The upstream element is preferably connected to the rod of aerosol-generating substrate and optionally at least a part of the downstream section by means of an outer wrapper, as described herein.

The aerosol-generating article according to the present invention may further comprise a downstream filter segment. The downstream filter segment may be located at the downstream end of the aerosol-generating article. The downstream end of the downstream filter segment may define the downstream end of the aerosol-generating article.

The downstream filter segment may be located downstream of a the aerosol-cooling element, which is described above. The downstream filter segment may extend between the aerosol-cooling element and the downstream end of the aerosol-generating article.

The downstream filter segment is preferably a solid plug, which may also be described as a ‘plain’ plug and is non-tubular. The filter segment therefore preferably has a substantially uniform transverse cross section. The downstream filter segment is preferably formed of a fibrous filtration material. The fibrous filtration material may be for filtering the aerosol that is generated from the aerosolgenerating substrate. Suitable fibrous filtration materials would be known to the skilled person. Particularly preferably, the at least one downstream filter segment comprises a cellulose acetate filter segment formed of cellulose acetate tow.

In certain preferred embodiments, the downstream section includes a single downstream filter segment. In alternative embodiments, the downstream section includes two or more downstream filter segments axially aligned in an abutting end to end relationship with each other.

Preferably, the downstream filter segment has a low particulate filtration efficiency.

Preferably, the downstream filter segment is circumscribed by a plug wrap. Preferably, the downstream filter segment is unventilated such that air does not enter the aerosol-generating article along the downstream filter segment.

The downstream filter segment is preferably connected to one or more of the adjacent upstream components of the aerosol-generating article by means of a tipping wrapper.

The downstream filter segment preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. The external diameter of a downstream filter segment may be substantially the same as the external diameter of the hollow tubular cooling element.

Preferably, the external diameter of the downstream filter segment is between 5 millimetres and 12 millimetres, more preferably between 6 millimetres and 10 millimetres, more preferably between 7 millimetres and 8 millimetres. In some embodiments, the external diameter of the downstream filter segment may be less than 7 millimetres, for example, between 5 millimetres and 7 millimetres, or between 6 millimetres and 7 millimetres.

As mentioned above, the downstream filter segment may be formed of a fibrous filtration material. The downstream filter segment may be formed of a porous material. The downstream filter segment may be formed of a biodegradable material. The downstream filter segment may be formed of a cellulose material, such as cellulose acetate.

The downstream filter segment may be formed of a polylactic acid based material. The downstream filter segment may be formed of a bioplastic material, preferably a starch-based bioplastic material. The downstream filter segment may be made by injection moulding or by extrusion.

The length of the downstream filter segment may be between 5 millimetres and 25 millimetres, or between 10 millimetres and 25 millimetres, or between 5 millimetres and 20 millimetres, or between 10 millimetres and 20 millimetres, or between 10 millimetres and 15 millimetres.

The ratio of the length of the downstream filter segment to the length of the aerosol-cooling element is preferably at least 1 , more preferably at least 1.1 , more preferably at least 1 .2, more preferably at least 1 .3, more preferably at least 1 .4. The ratio of the length of the downstream filter segment to the length of the aerosol-cooling element may be up to 2, preferably up to 1 .8.

The downstream filter segment preferably has a resistance to draw (RTD) of less than 15 millimetres H2O, or less than 12 millimetres H2O, or less than 10 millimetres H2O. Preferably, the downstream filter segment has an RTD of at least 2 millimetres H2O, or at least 4 millimetres H2O, or at least 6 millimetres H2O. For example, the downstream filter segment may have an RTD of between 2 millimetres H2O and 15 millimetres H2O, or between 4 millimetres H2O and 12 millimetres H2O, or between 6 millimetres H2O and 10 millimetres H2O. In particularly preferred embodiments, the downstream filter segment has an RTD of around 8.5 millimetres H2O.

The aerosol-generating article preferably has an overall length of from 40 millimetres to 80 millimetres, or from 40 millimetres to about 70 millimetres, or from 40 millimetres to about 60 millimetres, or from 45 millimetres to about 80 millimetres, or from about 45 millimetres to about 70 millimetres, or from 45 millimetres to 60 millimetres, or from 50 millimetres to 80 millimetres, or from 50 millimetres to about 70 millimetres or from about 50 millimetres to about 60 millimetres. In an exemplary embodiment, an overall length of the aerosol-generating article is about 45 millimetres.

The aerosol-generating article preferably has an external diameter of from about 5 millimetres to about 12 millimetres, or from about 6 millimetres to about 12 millimetres, or from about 7 millimetres to about 12 millimetres, or from about 5 millimetres to about 10 millimetres, or from about 6 millimetres to about 10 millimetres, or from about 7 millimetres to about 10 millimetres, or from about 5 millimetres to about 8 millimetres, or from about 6 millimetres to about 8 millimetres, or from about 7 millimetres to about 8 millimetres. In other embodiments, the aerosol-generating article has an external diameter of less than 7 millimetres.

The overall RTD of the aerosol-generating article is preferably at least 10 millimetres H₂O, more preferably at least 15 millimetres H₂O, more preferably at least 20 millimetres H₂O, more preferably at least 25 millimetres H₂O, more preferably at least 30 millimetres H₂O.

The overall RTD of the aerosol-generating article is preferably no more than 70 millimetres H2O, more preferably no more than 60 millimetres H2O, more preferably no more than 55 millimetres H2O, more preferably no more than 50 millimetres H2O, more preferably no more than 45 millimetres H2O.

For example, the overall RTD of the aerosol-generating article may be between 10 millimetres H2O and 70 millimetres H2O, or between 15 millimetres H2O and 60 millimetres H2O, or between 20 millimetres H2O and 55 millimetres H2O, or between 25 millimetres H2O and 45 millimetres H2O, or between 30 millimetres H2O and 45 millimetres H2O.

According to the present invention, there is further provided an aerosol-generating system comprising an aerosol-generating article according to the invention as described in detail above and an aerosol-generating device comprising a device cavity for receiving the aerosol-generating article and at least one heating element provided at or about the periphery of the device cavity.

The aerosol-generating device comprises a body or housing defining a device cavity. The device cavity may extend between a distal end and a mouth, or proximal, end. The distal end of the device cavity may be a closed end and the proximal end of the device cavity may be an open end. An aerosol-generating article may be inserted into the device cavity via the open end of the device cavity. The device cavity may be cylindrical in shape so as to conform to the same shape of an aerosol-generating article.

The aerosol-generating device further comprises a heater comprising one or more heating elements. The heater may be any suitable type of heater.

In some embodiments, the heater is arranged to heat the outer surface of the aerosolgenerating substrate. In some embodiments, the heater is arranged for insertion into an aerosolgenerating substrate when the aerosol-generating substrate is received within the cavity. The heater may be positioned within the device cavity.

The heater may comprise a single heater element or a plurality of heater elements. Any suitable type of heater element may be used. The heater may comprise at least one of a resistive heating element and an inductive heating assembly. The heater may comprise an external heater or external heating element.

The heater may externally heat the rod of aerosol-generating substrate when the aerosolgenerating article is received within the aerosol-generating device. Such an external heater may be provided on at least one side of the rod of aerosol-generating substrate when it is received within the heating chamber of the aerosol-generating device.

The heater may comprise at least one resistive heating element. The at least one resistive heating element may be any suitable type of resistive heating element. In some embodiments, the heater comprises only one resistive heating element. In some embodiments, the heater comprises a plurality of resistive heating elements. The heater may comprise at least one resistive heating element. Preferably, the heater assembly comprises a plurality of resistive heating elements. Preferably, the resistive heating elements are electrically connected in a parallel arrangement.

In some embodiments, the at least one heating element comprises an electrically insulating substrate, wherein the at least one resistive heating element is provided on the electrically insulating substrate.

In some embodiments, the heater comprises an inductive heating assembly. The inductive heating assembly may comprise an inductor coil. The aerosol-generating device may comprise a power supply configured to provide high frequency oscillating current to the inductor coil.

The heater may comprise an inductively heated element. The inductively heated element may be a susceptor element. In these embodiments, the susceptor element is preferably located in contact with the aerosol-generating substrate. In some embodiments, a susceptor element is located in the aerosol-generating device. In these embodiments, the susceptor element may be located in the heating chamber. The aerosol-generating device may comprise only one susceptor element. The aerosol-generating device may comprise a plurality of susceptor elements. In some embodiments, the susceptor element is preferably arranged to heat the outer surface of the aerosol-generating substrate.

The susceptor element may comprise any suitable material. Suitable materials for the elongate susceptor element include graphite, molybdenum, silicon carbide, stainless steels, niobium, aluminium, nickel, nickel containing compounds, titanium, and composites of metallic materials. Some susceptor elements comprise a metal or carbon. Advantageously the susceptor element may comprise or consist of a ferromagnetic material, for example, ferritic iron, a ferromagnetic alloy, such as ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. A suitable susceptor element may be, or comprise, aluminium.

As described in more detail above, in some embodiments where the aerosol-generating device comprises an induction coil, the aerosol-generating article may comprise at least one susceptor element.

The aerosol-generating device may comprise an air-flow channel extending between a channel inlet and a channel outlet. The air-flow channel may be configured to establish a fluid communication between the interior of the device cavity and the exterior of the aerosol-generating device. The air-flow channel of the aerosol-generating device may be defined within the body of the aerosol-generating device to enable fluid communication between the interior of the heating chamber and the exterior of the aerosol-generating device. When an aerosol-generating article is received within the heating chamber, the air-flow channel may be configured to provide air flow into the article in order to deliver generated aerosol to a user drawing from the mouth end of the article.

The aerosol-generating device may comprise a power supply. The power supply may be a DC power supply. In some embodiments, the power supply is a battery.

Below, there 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.

EX1 . An aerosol-generating article for producing an inhalable aerosol upon heating, the aerosol-generating article comprising: a rod of aerosol-generating substrate; a support element downstream of the rod of aerosol-generating substrate, the support element comprising a first hollow tubular element having an internal diameter D1 and defining a longitudinal cavity providing an unrestricted flow channel; and an aerosol-cooling element downstream of the support element, the aerosol-cooling element comprising a second hollow tubular element having an internal diameter D2 of at least 6 millimetres, and defining a longitudinal cavity providing an unrestricted flow channel.

EX2. An aerosol-generating article according to example EX1 , wherein a ratio between the internal diameter D2 of the second hollow tubular element and the internal diameter D1 of the first hollow tubular element is at least 1 .8.

EX3. An aerosol-generating article according to example EX1 or EX2, wherein the second hollow tubular element of the aerosol-cooling element has an internal diameter D2 of at least 6.5 millimetres.

EX4. An aerosol-generating article according to any preceding example, wherein the internal diameter D2 of the second hollow tubular element is less than 7.3 millimetres.

EX5. An aerosol-generating article according to any preceding example, wherein the wall thickness of the second hollow tubular element is less than 0.5 millimetres.

EX6. An aerosol-generating article according to any preceding example, wherein the wall thickness of the second hollow tubular element is less than 0.35 millimetres.

EX7. An aerosol-generating article according to any preceding example, wherein the wall thickness of the second hollow tubular element is at least 0.1 millimetres.

EX7. An aerosol-generating article according to any preceding example, wherein the second hollow tubular element is a paper tube formed of one or more paper layers.

EX8. An aerosol-generating article according to example EX7, wherein the second hollow tubular element is a paper tube formed of a plurality of overlapping paper layers.

EX9. An aerosol-generating article according to example EX8, wherein the plurality of overlapping paper layers are helically wound about the longitudinal axis of the second hollow tubular element.

EX10. An aerosol-generating article according to any of examples EX 7 to EX9, wherein each paper layer of the paper tube has a thickness of between 30 microns and 200 microns.

EX11. An aerosol-generating article according to example EX10, wherein the paper layers forming the paper tube have a different thickness to each other.

EX12. An aerosol-generating article according to example EX1 1 , wherein the paper tube comprises one or more layers of a first paper material and one or more layers of a second paper material, wherein the thickness of the second paper material is at least 25 microns greater than the thickness of the first paper material.

EX13. An aerosol-generating article according to any of examples EX 7 to EX12, wherein each paper layer of the paper tube has a grammage of between 25 grams per square metre and 150 grams per square metre.

EX14. An aerosol-generating article according to example EX13, wherein the paper layers forming the paper tube have a different grammage to each other. EX15. An aerosol-generating article according to example EX13 or EX14, wherein the paper tube comprises one or more layers of a first paper material and one or more layers of a second paper material, wherein the grammage of the second paper material is at least 25 grams per square metre greater than the grammage of the first paper material.

EX16. An aerosol-generating article according to any of examples EX7 to EX15, wherein the paper tube comprises at least one hydrophobic paper layer.

EX17. An aerosol-generating article according to example EX16, wherein the hydrophobic paper layer provides the inner surface of the paper tube.

EX18. An aerosol-generating article according to example EX16 or EX17, wherein the hydrophobic paper layer comprises a hydrophobic coating layer applied to the surface thereof.

EX19. An aerosol-generating article according to any of examples EX16 to EX18, wherein the hydrophobic paper layer comprises polyvinyl alcohol, silicon or a wax.

EX20. An aerosol-generating article according to any preceding example, wherein the aerosol-cooling element has a length of between 5 millimetres and 15 millimetres.

EX21 . An aerosol-generating article according to any preceding example, wherein the aerosol-cooling element has a length of less than 10 millimetres.

EX22. An aerosol-generating article according to any preceding example, wherein a ratio between the length of the aerosol-cooling element and the overall length of the aerosol-generating article substrate is at least 0.13.

EX23. An aerosol-generating article according to any preceding example, wherein the aerosol-cooling element further comprises a ventilation zone at a position along the second hollow tubular element.

EX24. An aerosol-generating article according to example EX23, wherein the aerosolgenerating article has a ventilation level of between 30 percent and 40 percent.

EX25. An aerosol-generating article according to any preceding example, wherein the first hollow tubular element has an internal diameter D1 of less than 5.5 millimetres.

EX26. An aerosol-generating article according to any preceding example, wherein the first hollow tubular element has an internal diameter D1 of less than 3.5 millimetres.

EX27. An aerosol-generating article according to any preceding example, wherein the first hollow tubular element has an internal diameter D1 of at least 1 .5 millimetres.

EX28. An aerosol-generating article according to any preceding example, wherein a ratio between the internal diameter of the second hollow tubular element and the internal diameter of the first hollow tubular element is at least 2.1 .

EX29. An aerosol-generating article according to any preceding example, wherein a ratio between the internal diameter of the second hollow tubular element and the internal diameter of the first hollow tubular element is less than 2.75. EX30. An aerosol-generating article according to any preceding example, wherein the wall thickness of the first hollow tubular element is at least 1 millimetre.

EX31 . An aerosol-generating article according to any preceding example, wherein the wall thickness of the first hollow tubular element is less than 3.5 millimetres.

EX32. An aerosol-generating article according to any preceding example, wherein the first hollow tubular element is a hollow acetate tube formed from cellulose acetate.

EX33. An aerosol-generating article according to any preceding example, wherein the support element has a length of between 5 millimetres and 15 millimetres.

EX34. An aerosol-generating article according to any preceding example, wherein the support element has a length of less than 10 millimetres.

EX35. An aerosol-generating article according to any preceding example, wherein a ratio between the length of the support element and the overall length of the aerosol-generating article is at least 0.13.

EX36. An aerosol-generating article according to any preceding example, wherein a ratio between the length of the aerosol-cooling element and the length of the support element is at least 0.8.

EX37. An aerosol-generating article according to any preceding example, wherein a ratio between the length of the aerosol-cooling element and the length of the support element is at least 1 .5.

EX38. An aerosol-generating article according to any preceding example, wherein the rod of aerosol-generating substrate has a length of at least 8 millimetres.

EX39. An aerosol-generating article according to any preceding example, wherein the rod of aerosol-generating substrate comprises homogenised tobacco material.

EX40. An aerosol-generating article according to any preceding example, wherein the rod of aerosol-generating substrate comprises tobacco cut filler.

EX41 . An aerosol-generating article according to any preceding example, wherein the rod of aerosol-generating substrate comprises a cellulosic based film forming agent, nicotine and the aerosol former.

EX42. An aerosol-generating article according to any preceding example, wherein the rod of aerosol-generating substrate comprises one or more elongate susceptor elements.

EX43. An aerosol-generating article according to any preceding example, further comprising an upstream element located upstream of the rod of aerosol-generating substrate.

EX44. An aerosol-generating article according to any preceding example, further comprising a downstream filter segment downstream of the aerosol-cooling element.

EX45. An aerosol-generating system comprising an aerosol-generating article according to any of the preceding examples and an aerosol-generating device comprising a device cavity for receiving the aerosol-generating article and at least one heating element provided at or about the periphery of the device cavity.

In the following, the invention will be further described with reference to the drawing of the accompanying Figure 1 , which shows a schematic side sectional view of an aerosol-generating article in accordance with the invention.

The aerosol-generating article 10 shown in Figure 1 comprises a rod 12 of aerosolgenerating substrate 12 and a downstream section 14 at a location downstream of the rod 12 of aerosol-generating substrate. Further, the aerosol-generating article 10 comprises an upstream section 16 at a location upstream of the rod 12 of aerosol-generating substrate. Thus, the aerosolgenerating article 10 extends from an upstream or distal end 18 to a downstream or mouth end 20.

The aerosol-generating article has an overall length of about 45 millimetres.

The downstream section 14 comprises a support element 22 located immediately downstream of the rod 12 of aerosol-generating substrate, the support element 22 being in longitudinal alignment with the rod 12. In the embodiment of Figure 1 , the upstream end of the support element 22 abuts the downstream end of the rod 12 of aerosol-generating substrate. In addition, the downstream section 14 comprises an aerosol-cooling element 24 located immediately downstream of the support element 22, the aerosol-cooling element 24 being in longitudinal alignment with the rod 12 and the support element 22. In the embodiment of Figure 1 , the upstream end of the aerosol-cooling element 24 abuts the downstream end of the support element 22.

The support element 22 comprises a first hollow tubular element 26. The first hollow tubular element 26 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The first hollow tubular element 26 defines an internal cavity 28 that extends all the way from an upstream end 30 of the first hollow tubular element to an downstream end 32 of the first hollow tubular element 26. The internal cavity 28 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 28. The first hollow tubular element 26 - and, as a consequence, the support element 22 - does not substantially contribute to the overall RTD of the aerosol-generating article 10. Specifically, the RTD of the first hollow tubular element 26 is substantially 0 millimetres H₂O.

The first hollow tubular element 26 has a length of about 8 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter (D1 ) of about 3.3 millimetres. Thus, a thickness of a peripheral wall of the first hollow tubular element 26 is approximately 2 millimetres.

The aerosol-cooling element 24 comprises a second hollow tubular element 34. The second hollow tubular element 34 is provided in the form of a paper tube formed of three spirally wound paper layers. A first, inner paper layer has a thickness of 137 microns and a grammage of 120 gsm. A second, middle paper layer has a thickness of 100 microns and a grammage of 78 gsm. A third, outer paper layer has a thickness of 45 microns and a grammage of 32 gsm.

The second hollow tubular element 34 defines an internal cavity 36 that extends all the way from an upstream end 38 of the second hollow tubular element to a downstream end 40 of the second hollow tubular element 34. The internal cavity 36 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 36. The second hollow tubular element 34 - and, as a consequence, the aerosol-cooling element 24 - does not substantially contribute to the overall RTD of the aerosol-generating article 10. Specifically, the RTD of the second hollow tubular element 34 is substantially 0 millimetres H2O.

The second hollow tubular element 34 has a length of about 8 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter (D2) of about 6.9 millimetres. Thus, a thickness of a peripheral wall of the second hollow tubular element 34 is about 0.18 millimetres. A ratio between the internal diameter (D2) of the second hollow tubular element 34 and the internal diameter (D1 ) of the first hollow tubular element 26 is about 2.1.

The aerosol-generating article 10 comprises a ventilation zone 60 provided at a location along the second hollow tubular element 34. In more detail, the ventilation zone 60 is provided at about 2 millimetres from the upstream end 38 of the second hollow tubular element 34. A ventilation level of the aerosol-generating article 10 is about 35 percent.

In the embodiment of Figure 1 , the downstream section 14 further comprises a mouthpiece element 42 positioned immediately downstream of the aerosol-cooling element 24. As shown in the drawing of Figure 1 , an upstream end of the mouthpiece element 42 abuts the downstream end 40 of the second hollow tubular element 34.

The mouthpiece element 42 is provided in the form of a cylindrical plug of low-density cellulose acetate.

The mouthpiece element 42 has a length of about 12 millimetres and an external diameter of about 7.25 millimetres. The RTD of the mouthpiece element 42 is about 12 millimetres H2O.

The rod 12 comprises an aerosol-generating substrate of one of the types described above.

The rod 12 of aerosol-generating substrate has an external diameter of about 7.25 millimetres and a length of about 12 millimetres.

The aerosol-generating article 10 further comprises an elongate susceptor element 44 within the rod 12 of aerosol-generating substrate. In more detail, the susceptor element 44 is arranged substantially longitudinally within the aerosol-generating substrate, such as to be approximately parallel to the longitudinal direction of the rod 12. As shown in the drawing of Figure 1 , the susceptor element 44 is positioned in a radially central position within the rod and extends effectively along the longitudinal axis of the rod 12. The susceptor element 44 extends all the way from an upstream end to a downstream end of the rod 12. In effect, the susceptor element 44 has substantially the same length as the rod 12 of aerosol-generating substrate.

In the embodiment of Figure 1 , the susceptor element 44 is provided in the form of a strip and has a length of about 12 millimetres, a thickness of about 60 micrometres, and a width of about 4 millimetres. The upstream section 16 comprises an upstream element 46 located immediately upstream of the rod 12 of aerosol-generating substrate, the upstream element 46 being in longitudinal alignment with the rod 12. In the embodiment of Figure 1 , the downstream end of the upstream element 46 abuts the upstream end of the rod 12 of aerosol-generating substrate. This advantageously prevents the susceptor element 44 from being dislodged. Further, this ensures that the consumer cannot accidentally contact the heated susceptor element 44 after use.

The upstream element 46 is provided in the form of a cylindrical plug of cellulose acetate circumscribed by a stiff wrapper. The upstream element 46 has a length of about 5 millimetres. The RTD of the upstream element 46 is about 30 millimetres H2O.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1. An aerosol-generating article for producing an inhalable aerosol upon heating, the aerosol-generating article comprising: a rod of aerosol-generating substrate; a support element downstream of the rod of aerosol-generating substrate, the support element comprising a first hollow tubular element having an internal diameter D1 and defining a longitudinal cavity providing an unrestricted flow channel; and an aerosol-cooling element downstream of the support element, the aerosol-cooling element comprising a second hollow tubular element having an internal diameter D2 of at least 6 millimetres, and defining a longitudinal cavity providing an unrestricted flow channel, wherein a ratio between the internal diameter D2 of the second hollow tubular element and the internal diameter D1 of the first hollow tubular element is at least 1 .8.

2. An aerosol-generating article according to claim 1 , wherein the second hollow tubular element of the aerosol-cooling element has a wall thickness of less than 0.5 millimetres.

3. An aerosol-generating article according to claim 1 or 2, wherein the first hollow tubular element of the support element has an internal diameter D1 of less than 5.5 millimetres.

4. An aerosol-generating article according to any preceding claim, wherein the first hollow tubular element of the support element has a wall thickness of at least 2 millimetres.

5. An aerosol-generating article according to any preceding claim, wherein the aerosolcooling element further comprises a ventilation zone at a position along the second hollow tubular element.

6. An aerosol-generating article according to any preceding claim, wherein the second hollow tubular element of the aerosol-cooling element is a paper tube comprising a plurality of overlapping layers of paper.

7. An aerosol-generating article according to claim 6, wherein the plurality of layers are helically wound about the longitudinal axis of the second hollow tubular element.

8. An aerosol-generating article according to claim 5 or 6, wherein the paper tube comprises a hydrophobic coating layer on the inner surface.

9. An aerosol-generating article according to any of claims 5 to 8, wherein the paper tube comprises one or more layers of a first paper material and one or more layers of a second paper material, wherein the thickness of the second paper material is greater than the thickness of the first paper material.

10. An aerosol-generating article according to any preceding claim, wherein the length of the aerosol-cooling element is less than 10 millimetres.

11. An aerosol-generating article according to any preceding claim, where the length of the support element is at least 6 millimetres.

12. An aerosol-generating article according to any preceding claim, further comprising an elongate susceptor element within the rod of aerosol-generating substrate.

13. An aerosol-generating article according to any preceding claim, further comprising an upstream element provided upstream of the rod of aerosol-generating substrate.

14. An aerosol-generating article according to any preceding claim, further comprising a mouthpiece element downstream of the aerosol-cooling element, the mouthpiece element comprising at least one mouthpiece filter segment formed of a fibrous filtration material.

15 An aerosol-generating system comprising an aerosol-generating article according to any one of claims 1 to 14 and an aerosol-generating device comprising a device cavity for receiving the aerosol-generating article and at least one heating element provided at or about the periphery of the heating chamber.