WO2024089243A1

WO2024089243A1 - An aerosol-generating article comprising a first tubular element and a second tubular element

Info

Publication number: WO2024089243A1
Application number: PCT/EP2023/080068
Authority: WO
Inventors: Matteo Bologna; Onur DAYIOGLU
Original assignee: Philip Morris Products S.A.
Priority date: 2022-10-27
Filing date: 2023-10-27
Publication date: 2024-05-02

Abstract

An aerosol-generating article (1) comprising a plurality of elements assembled in the form of a rod. The plurality of elements comprises an aerosol-forming substrate (10). The plurality of elements also comprises a first tubular element (20) comprising an upstream end wall (21) defining a first opening (22) for allowing fluid communication between an interior of the first tubular element and an exterior of the first tubular element. The plurality of elements further comprises a second tubular element (30) comprising a second tubular element end wall (31) defining a second opening (32) for allowing fluid communication between an interior of the second tubular element and an exterior of the second tubular element. The first tubular element (20) is positioned within the rod upstream of, and adjacent to, the second tubular element (30).

Description

AN AEROSOL-GENERATING ARTICLE COMPRISING A FIRST TUBULAR ELEMENT AND A SECOND TUBULAR ELEMENT

The present disclosure relates to an aerosol-generating article comprising an aerosolforming substrate in which the aerosol-generating article is adapted to produce an inhalable aerosol.

Aerosol-generating articles in which an aerosol-forming substrate, such as a tobaccocontaining substrate, is heated rather than combusted, are known in the art. Typically in such heated aerosol-generating articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-forming substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosolgenerating article, volatile compounds are released from the aerosol-forming substrate by heat transfer from the heat source. The volatile compounds are then entrained in air that is drawn through the aerosol-generating article. As the volatile compounds cool, they condense to form an aerosol.

It has been known to provide aerosol-generating articles with one or more elements, in addition to an aerosol-forming substrate, that are configured to perform certain functions to enhance the consumer experience. For example, WO 2013/120565 A2 discloses an aerosol-generating article comprising an aerosol-cooling element for cooling an aerosol formed from the substrate. In one embodiment disclosed in WO 2013/120565 A2, a hollow cellulose acetate tube is located immediately downstream of the aerosol-forming substrate, and an aerosol-cooling element made from a sheet of polylactic acid is positioned downstream of the hollow cellulose acetate tube. It is described that a function of the hollow cellulose acetate tube is to prevent the aerosol-forming substrate from being forced downstream when a heating element is inserted into the aerosol-forming substrate.

Providing an aerosol-generating article with such elements, in addition to the aerosolforming substrate, can increase the costs and complexity of manufacturing the aerosolgenerating article. Furthermore, these elements can have an undesirable effect on the resistance to draw (RTD) of the aerosol-generating article. For example, an aerosolgenerating article having an RTD that is too low or too high may lead to an unsatisfactory consumer experience.

It would be desirable to provide an aerosol-generating article with one or more elements that can enhance the consumer experience but which are relatively simple and inexpensive to manufacture. In particular, it would be desirable that the RTD of the element can be controlled to provide a satisfactory RTD.

The present disclosure relates to an aerosol-generating article. The aerosolgenerating article may comprise a plurality of elements assembled in the form of a rod. The plurality of elements may comprise an aerosol-forming substrate. The plurality of elements may also comprise a first tubular element. The first tubular element may comprise an upstream end wall defining a first opening for allowing fluid communication between an interior of the first tubular element and an exterior of the first tubular element. The plurality of elements may further comprise a second tubular element. The second tubular element may comprise a second tubular element end wall defining a second opening for allowing fluid communication between an interior of the second tubular element and an exterior of the second tubular element. The first tubular element may be positioned within the rod upstream of, and adjacent to, the second tubular element.

According to the present disclosure, there is provided an aerosol-generating article. The aerosol-generating article comprises a plurality of elements assembled in the form of a rod. The plurality of elements comprises an aerosol-forming substrate. The plurality of elements also comprises a first tubular element comprising an upstream end wall defining a first opening for allowing fluid communication between an interior of the first tubular element and an exterior of the first tubular element. The plurality of elements further comprises a second tubular element comprising a second tubular element end wall defining a second opening for allowing fluid communication between an interior of the second tubular element and an exterior of the second tubular element. The first tubular element is positioned within the rod upstream of, and adjacent to, the second tubular element.

The first tubular element may be referred to as the upstream tubular element. The second tubular element may be referred to as the downstream tubular element.

The aerosol-generating article may comprise a substrate portion. The substrate portion may comprise the aerosol-forming substrate. The substrate portion may comprise a capsule. The aerosol-forming substrate may be disposed within the capsule.

By providing two separate tubular elements, each having an end wall, that are adjacent to one another, the tubular elements can provide one or more functions to enhance the consumer experience. For example, when positioned downstream of the aerosol-forming substrate, the tubular elements can function as one or more of an aerosol-cooling element and a filter element. Additionally, when positioned upstream of the aerosol-forming substrate, the tubular elements can function as a front plug. This means that the number of elements in the aerosol-generating article may be reduced and the number of different types of elements that need to be manufactured can be reduced because the tubular elements can perform a number of different functions. Advantageously, this means that the manufacturing process can be simplified and manufacturing costs can be reduced.

By providing two separate tubular elements, each having an end wall, that are adjacent to one another rather than a single tubular element having two end walls provides a number of benefits. For example, it has been found that in a continuous manufacturing process it can be quicker and more efficient to provide two tubular elements each with a single end wall than it is to provide a single tubular element with two end walls. This is because of the need to only form a single end wall on each tubular element. As another example, each tubular element can be optimised depending on its location within the aerosolgenerating article. This may include forming each tubular element from a different material or forming each tubular element from different thicknesses of materials. For example, the first tubular element may be exposed to high temperatures from a heating element. This means the first tubular element may need to be made out of a heat resistant material. On the other hand, the second tubular element may not be exposed to high temperatures but may be exposed to saliva from a user’s mouth. This means the second tubular element may need to have a hydrophobic coating. Advantageously, this can lead to an optimised aerosolgenerating article that is relatively simple and cost effective to manufacture.

As used herein, the term “aerosol-generating article” refers to an article that is capable of producing and delivering an inhalable aerosol to a consumer.

As used herein, the term “aerosol-forming substrate” refers to a substrate capable of forming an inhalable aerosol. The aerosol-forming substrate may be capable of releasing volatile compounds to form the inhalable aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate.

As used herein, the term “rod” refers to an elongate element. The rod may have a substantially polygonal transverse cross-sectional shape. Preferably, a circular, oval or elliptical transverse cross-sectional shape.

As used herein, the term “elongate” refers to an element that has a length dimension that is greater than its width dimension or its diameter dimension, for example twice or more its width dimension or its diameter dimension.

As used herein, the term “transverse” refers to the direction that is perpendicular to the longitudinal direction. Any reference to the “cross-section” of the aerosol-generating article or a component of the aerosol-generating article refers to the transverse cross-section unless stated otherwise.

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 end and the downstream end of the aerosol-generating article. During use, air is drawn through the aerosol-generating article in the longitudinal direction.

As used herein, the terms “upstream” and “downstream” refers to the relative positions of elements, or portions of elements, of the aerosol-generating article in relation to the longitudinal direction.

As used herein, the term “length” refers to the dimension of the, or a component of the, aerosol-generating article in the longitudinal direction. For example, it may be used to denote the dimension of the aerosol-forming substrate, the first tubular element or the second tubular element in the longitudinal direction.

As used herein, the term “equivalent diameter” refers to the diameter of a circular opening having the same cross-sectional area as the opening.

As used herein, the term "tubular element" refers to an elongate element defining a lumen or airflow passage in a longitudinal direction thereof. In particular, the term "tubular" is used to describe a tubular element having a substantially circular transverse cross- sectional shape and defining at least one airflow conduit establishing an uninterrupted fluid communication between an upstream end of the tubular element and a downstream end of the tubular element. However, it will be understood that alternative geometries (for example, alternative transverse cross-sectional shape) of the tubular element may be possible. For example, the tubular element may have a circular, oval or elliptical transverse cross-sectional shape.

As used herein, the term “upstream end wall” refers to a wall at an extreme upstream end of the first tubular element. The upstream end wall extends substantially transversely to the longitudinal direction of the first tubular element. The material forming the upstream end wall may be substantially air impermeable.

As used herein, the term “second tubular element end wall” refers to a wall at an extreme end of the second tubular element. The second tubular element end wall extends substantially transversely to the longitudinal direction of the second tubular element. The material forming the second tubular element end wall may be substantially air impermeable.

As used herein, the term “adjacent to” refers to a first element of the aerosolgenerating article being longitudinally positioned next to a second element of the aerosolgenerating article. In particular, this term indicates that there are no other elements of the aerosol-generating article disposed between the first element of the aerosol-generating article and the second element of the aerosol-generating article in the longitudinal direction.

As used herein, the term “filter” refers to a section or element of the aerosolgenerating article that is configured to remove at least partially gas phase or particulate phase constituents or both gas phase and particulate phase constituents from the mainstream aerosol drawn through the filter.

As used herein, the term “aerosol-generating device” refers to a device that interacts with an aerosol-forming substrate to generate an aerosol from the aerosol-forming substrate. The aerosol-generating device may be a heated aerosol-generating device. The aerosolgenerating device may be an electrically heated aerosol-generating device. For example, the aerosol-generating device may comprise one or more components used to supply energy from a power supply to an aerosol-forming substrate to generate an aerosol. The aerosol- generating device may be a smoking device that interacts with an aerosol-forming substrate to generate an aerosol that is directly inhalable into a user's lungs through the user's mouth.

In a conventional cigarette, a user applies a flame to one end of the cigarette and the localised heat provided by the flame and the oxygen in the air causes the end of the cigarette to ignite, and the resulting combustion generates an inhalable smoke. By contrast, in heated aerosol-generating articles, an aerosol is generated by heating, rather than combusting, an aerosol-forming substrate. Known heated aerosol-generating articles include, for example, electrically heated aerosol-generating articles and aerosol-generating articles in which an aerosol is generated by the transfer of heat from a combustible fuel element or heat source to a physically separate aerosol-forming substrate.

The aerosol-generating article according to the present disclosure may be a heated aerosol-generating article. The aerosol-generating article may be an electrically heated aerosol-generating article. Heated aerosol-generating articles may produce a smaller number of components that need to be filtered before inhalation by a consumer compared to an aerosol-generating article in which the aerosol-forming substrate is configured to be combusted. Advantageously, this may mean that the aerosol-generating article can have fewer components downstream of the aerosol-forming substrate leading to an aerosolgenerating article that is cheaper to manufacture. Additionally, this may mean that for the same sized aerosol-generating article, the aerosol-generating article can be provided with a larger aerosol-forming substrate which may provide a consumer with a longer usage session.

The downstream end of the first tubular element may be spaced, in the longitudinal direction, from the upstream end of the second tubular element. A gap of empty space may separate the downstream end of the first tubular element and the upstream end of the second tubular element in the longitudinal direction of the aerosol-generating article. The gap may have a length of 5 millimetres or less. The gap may have a length of 4 millimetres or less. The gap may have a length 3 millimetres or less. The gap may have a length of 2 millimetres or less. The gap may have a length of 1 millimetre or less. Advantageously, such a gap may increase the length of the internal passage between upstream end wall of the first tubular element, and the second tubular element end wall whilst reducing the amount of material, and thereby reducing cost, that is required compared to a single tubular element having the same distance between upstream and downstream end walls. This is particularly the case when the second tubular element end wall is positioned at the downstream end of the second tubular element.

The downstream end of the first tubular element may be in physical contact with the upstream end of the second tubular element. The downstream end of the first tubular element may abut the upstream end of the second tubular element. This may mean that there is no gap between the first tubular element and the second tubular element. Advantageously, this may prevent one or more of air, volatile compounds, and aerosol from escaping in a radial direction via a gap between the first tubular element and second tubular element. Advantageously, this may also mean that a gap between the first tubular element and second tubular element does not need to be circumscribed by a non-porous wrapper.

The downstream end of the first tubular element may overlap the upstream end of the second tubular element in the longitudinal direction. For example, it may overlap by between about 1 millimetre and about 5 millimetres. In particular, the downstream end of the first tubular element may circumscribe the upstream end of the second tubular element. Alternatively, the upstream end of the second tubular element may circumscribe the downstream end of the first tubular element. The downstream end of the first tubular element may be positioned within the second tubular element, or the upstream end of the second tubular element may be positioned within the first tubular element. Advantageously, this may prevent one or more of air, volatile compounds, and aerosol from escaping in a radial direction via a gap between the first tubular element and second tubular element.

The first tubular element and the second tubular element may be positioned upstream of the aerosol-forming substrate. Therefore, the first tubular element and the second tubular element may act as a front plug whilst allowing air and a heating element to enter the aerosolgenerating article through the first opening. Advantageously, such a front plug may be relatively inexpensive compared to traditional front plugs, such as those made from cellulose acetate.

The first tubular element may be the most upstream element of the aerosolgenerating article. The first tubular element may be positioned at the extreme upstream end of the aerosol-generating article. The upstream end wall of the first tubular element may be positioned at the extreme upstream end of the aerosol-generating article. Advantageously, this may mean the first tubular element and second tubular element may prevent any elements of the aerosol-generating article, or portion of any element, from exiting the downstream end of the aerosol-generating article.

The second tubular element may be positioned adjacent the upstream end of the substrate portion. The second tubular element may be positioned adjacent to the upstream end of the aerosol-forming substrate. There may be a gap between the downstream end of the second tubular element and the upstream end of the aerosol-forming substrate. The gap may have a length of at least about 1 millimetre, at least about 2 millimetres, at least about 3 millimetres, at least about 4 millimetres, or at least about 5 millimetres. The gap may have a length of between about 1 millimetre and about 5 millimetres. Such a gap may allow the air exiting the downstream end of the second tubular element to move in a radial direction before passing through the aerosol-forming substrate. This is particularly the case when the second tubular element end wall is positioned at the downstream end of the second tubular element. Advantageously, this may allow air to pass through the entire transverse cross-section of the aerosol-forming substrate. It has been found that a gap having a length between about 1 millimetre and about 5 millimetres provides a sufficient region for air to move in a radial direction without creating a large region of recirculating air.

The second tubular element may be in physical contact with an upstream end of the aerosol-forming substrate. The downstream end of the second tubular element may be in physical contact with an upstream end of the aerosol-forming substrate. Advantageously, this may prevent movement of the aerosol-generating article towards the downstream end of the aerosol-generating article. Additionally, this may ensure that a heating element can be consistently located relative to the aerosol-forming substrate due to the limitation in the movement of the aerosol-forming substrate. The second tubular element may be in physical contact with an upstream end of the substrate portion. The downstream end of the second tubular element may be in physical contact with an upstream end of the substrate portion.

The first tubular element and the second tubular element may be positioned downstream of the aerosol-forming substrate. Advantageously, therefore, the first tubular element and the second tubular element may interact with one or more of the air, volatile compounds and aerosol downstream of the aerosol-forming substrate. For example, the first tubular element and the second tubular element may act as one or more of a cooling element, a filter element and a mouth piece.

In many known aerosol-generating articles, there is a filter element positioned at the downstream end of the aerosol-generating article. Typically, filter elements are configured in such a way that they present an RTD of the aerosol flowing through them. This means that the RTD through the filter element must be taken into account when configuring the overall RTD of the aerosol-generating article. This can present challenges when there are a number of components within the aerosol-generating article and it is desired to obtain a consistent RTD between aerosol-generating articles that are manufactured. In some known aerosolgenerating articles, the filter element is made from cellulose acetate which may present an RTD.

In the aerosol-generating article of the present disclosure, there may be no filter element made from cellulose acetate positioned downstream of the second tubular element. In fact, there may be no filter element positioned downstream of the second tubular element. Additionally, or alternatively, any element positioned downstream of the second tubular element may have a resistance to draw that is less than the resistance to draw of one or more of the first tubular element, the second tubular element, or the combination of the first tubular element and the second tubular element. For example, any element positioned downstream of the second tubular element may have a resistance to draw of less than about 30 millimetres H2O, preferably less than about 20 millimetres H2O, more preferably less than about 10 millimetres H2O, or most preferably a resistance to draw of about 0 millimetres H2O. Advantageously, this means that it is easier to provide a consistent RTD between aerosolgenerating articles that are manufactured. The term “any element positioned downstream of the second tubular element” includes there being no elements positioned downstream of the second tubular element.

Any element positioned downstream of the second tubular element may be hollow. Any element positioned downstream of the second tubular element may be a tubular.

The second tubular element may be the most downstream element of the aerosolgenerating article. Therefore, there may be no elements positioned between the downstream end of the second tubular element and the extreme downstream end of the aerosolgenerating article. Advantageously, this may mean that the aerosol-generating article is easier to manufacture due to a reduced number of components needed to be assembled within the aerosol-generating article. Additionally, this may allow the constriction of the second opening of the second tubular element to accelerate aerosol into a consumer’s mouth without the accelerated aerosol being disturbed by elements downstream of the second tubular element. This may provide the consumer with a pleasant sensation.

The downstream end of the second tubular element may be spaced from the downstream end of the aerosol-generating article. By spacing the downstream end of the second tubular element from the downstream end of the aerosol-generating article, the stream of aerosol exiting the downstream end of the second tubular element has a region to expand before enter a consumer’s mouth. Advantageously, this may provide a stream of aerosol into a consumer’s mouth that has a feeling of greater volume which may provide greater consumer satisfaction. This is particularly the case when the second tubular element end wall is positioned at the downstream end of the second tubular element.

The downstream end of the second tubular element may be positioned between about 3 millimetres and about 20 millimetres from the downstream end of the aerosolgenerating article. The downstream end of the second tubular element may be positioned between about 3 millimetres and about 15 millimetres from the downstream end of the aerosol-generating article. The downstream end of the second tubular element may be positioned between about 3 millimetres and about 10 millimetres from the downstream end of the aerosol-generating article. The downstream end of the second tubular element may be positioned between about 3 millimetres and about 8 millimetres from the downstream end of the aerosol-generating article. These ranges provide a compromise between providing a region for the aerosol to expand prior to entering a consumer’s mouth, and not significantly increasing the overall length of the aerosol-generating article and therefore cost. Advantageously, it has been found that the range of between about 3 millimetres and about 8 millimetres provides a good trade-off between the region for expansion of the aerosol and the length of the aerosol-generating article.

The downstream end of the second tubular element may be positioned less than 20 millimetres from the downstream end of the aerosol-generating article. The downstream end of the second tubular element may be positioned less than 15 millimetres from the downstream end of the aerosol-generating article. The downstream end of the second tubular element may be positioned less than 10 millimetres from the downstream end of the aerosol-generating article. The downstream end of the second tubular element may be positioned less than 5 millimetres from the downstream end of the aerosol-generating article. The downstream end of the second tubular element may be positioned less than 3 millimetres from the downstream end of the aerosol-generating article.

The second tubular element may be positioned at the extreme downstream end of the aerosol-generating article. The downstream end of the second tubular element may be positioned at the extreme downstream end of the aerosol-generating article. Advantageously, the second tubular element may therefore act as a mouthpiece element and support a consumer’s lips that circumscribe the aerosol-generating article when they draw on the aerosol-generating article.

The upstream end wall of the first tubular element may be positioned adjacent to the aerosol-forming substrate and not in physical contact with the aerosol-forming substrate. A gap of empty space may separate the upstream end wall of the first tubular element and downstream end of the aerosol-forming substrate in the longitudinal direction of the aerosolgenerating article. The upstream end wall of the first tubular element may be positioned adjacent to the substrate portion. A gap of empty space may separate the upstream end wall of the first tubular element and the downstream end of the substrate portion. The gap may be 5 millimetres or less. The gap may be 4 millimetres or less. The gap may be 3 millimetres or less. The gap may be 2 millimetres or less. The gap may be 1 millimetre or less. Advantageously, such a gap may provide a space for loose particles or pieces from the aerosol-forming substrate to congregate during use of the aerosol-generating article.

The first tubular element may be positioned adjacent to the downstream end of the aerosol-forming substrate. The first tubular element may be in physical contact with the downstream end of the aerosol-forming substrate. The upstream end wall of the first tubular element may be in physical contact with the downstream end of the aerosol-forming substrate. Advantageously, physical contact between the upstream end of the tubular element and the aerosol-forming substrate may prevent the aerosol-forming substrate from moving downstream, for example as the aerosol-forming substrate dries out and shrinks or when a heating element is inserted into the aerosol-forming substrate from the upstream end of the aerosol-generating article. The first tubular element may be positioned adjacent to the downstream end of the substrate portion. The first tubular element may be in physical contact with the downstream end of the substrate portion. The upstream end wall of the first tubular element may be in physical contact with the downstream end of the substrate portion.

The upstream end wall may be formed by a first folded end portion. The second tubular element end wall may be formed by a second folded end portion. By providing end walls that are formed from a folded end portion of the respective tubular element, each tubular element can be configured to have a desired RTD through configuration of the size and shape of the end wall and opening. In particular, each tubular element and its end wall can be manufactured efficiently and at high speed, with a satisfactory RTD and low RTD variability from one article to another. Furthermore, the configuration of each tubular element and its end wall means that the RTD can be localised at a specific longitudinal position of the tubular element, namely at the end wall, rather than being continuously distributed along the length of the tubular element. Advantageously, this means that the tubular elements can be configured to have more consistent properties whilst maintaining a cost-effective manufacturing process.

The first folded end portion may be a flanged end portion. The second folded end portion may be a flanged end portion.

The second tubular element end wall may be positioned at the upstream end of the second tubular element. Alternatively, the second tubular element end wall may be positioned at the downstream end of the second tubular element. That is, the second tubular end wall may be referred to as a downstream end wall.

There may be no end wall at the downstream end of the first tubular element. There may be no end wall at the upstream end of the second tubular element. Alternatively, there may be no end wall at the downstream end of the second tubular element. There may be no end wall at both the downstream end of the first tubular element and the upstream end of the second tubular element. Advantageously, this may provide an unrestricted passage for fluid flow between the upstream end wall of the first tubular element and the downstream end wall of the second tubular element.

The first tubular element may comprise a first cavity extending from the upstream end wall of the first tubular element to the downstream end of the first tubular element. The first cavity may be empty. Advantageously, this may provide an uninterrupted passage for fluid flow through the first tubular element.

The first cavity may have a diameter that is at least about 50 percent a diameter of the first tubular element. The first cavity may have a diameter that is at least about 60 percent a diameter of the first tubular element. The first cavity may have a diameter that is at least about 70 percent a diameter of the first tubular element. The first cavity may have a diameter that is at least about 80 percent a diameter of the first tubular element. The first cavity may have a diameter that is at least about 90 percent a diameter of the first tubular element. Preferably, the first cavity may have a diameter that is at least about 95 percent a diameter of the first tubular element. Advantageously, having a diameter of the first cavity being at least about 50 percent of the diameter of the first tubular element has been found to provide the first tubular element having good structural rigidity. It has been found that, when the diameter of the cavity is at least about 95 percent of the diameter of the first tubular element, a compromise between structural rigidity and reduction in the material used can be achieved.

The diameter of the first cavity may increase between the upstream end wall of the first tubular element and the downstream end of the first tubular element. The diameter of the first cavity may increase from the upstream end wall of the first tubular element to the downstream end of the first tubular element. Advantageously, an increasing diameter may act to decelerate the flow within the first tubular element.

The diameter of the first cavity may decrease between the upstream end wall of the first tubular element and the downstream end of the first tubular element. The diameter of the first cavity may decrease from the upstream end wall of the first tubular element to the downstream end of the first tubular element. Advantageously, a decreasing diameter may act to accelerate the flow within the first tubular element.

The diameter of the first cavity may be substantially constant between the upstream end wall of the first tubular element and the downstream end of the first tubular element. The diameter of the cavity may be substantially constant from the upstream end wall of the first tubular element to the downstream end of the first tubular element. Advantageously, a substantially constant diameter may help to maintain a constant flow rate throughout the first cavity, which may allow the flow to have equal contact time with all portions of the internal wall of the first cavity.

The second tubular element may comprise a second cavity extending from the upstream end of the second tubular element to the downstream end of the second tubular element. The second cavity may be empty. Advantageously, this may provide an uninterrupted passage for fluid flow through second tubular element.

The second cavity may have a diameter that is at least about 50 percent a diameter of the second tubular element. The second cavity may have a diameter that is at least about 60 percent a diameter of the second tubular element. The second cavity may have a diameter that is at least about 70 percent a diameter of the second tubular element. The second cavity may have a diameter that is at least about 80 percent a diameter of the second tubular element. The second cavity may have a diameter that is at least about 90 percent a diameter of the second tubular element. The second cavity may have a diameter that is at least about 95 percent a diameter of the second tubular element. Advantageously, having a diameter of the second cavity being at least about 50 percent of the diameter of the second tubular element has been found to provide the second tubular element having good structural rigidity. It has been found that, when the diameter of the second cavity is at least about 95 percent of the diameter of the second tubular element, a compromise between structural rigidity and reduction in the material used can be achieved.

The diameter of the second cavity may increase between the upstream end of the second tubular element and the downstream end of the second tubular element. The diameter of the second cavity may increase from the upstream end of the second tubular element to the downstream end of the second tubular element.

The diameter of the second cavity may decrease between the upstream end of the second tubular element and the downstream end of the second tubular element. The diameter of the second cavity may decrease from the upstream end of the second tubular element to the downstream end of the second tubular element.

The diameter of the second cavity may be substantially constant between the upstream end of the second tubular element and the downstream end of the second tubular element. The diameter of the second cavity may be substantially constant from the upstream end of the second tubular element to the downstream end of the second tubular element.

The diameter of the first cavity may be greater than the diameter of the second cavity. The diameter of the first cavity may be less than the diameter of the second cavity. The diameter of the first cavity may be substantially the same as the diameter of the second cavity.

The aerosol-generating article may comprise a continuous cavity extending from the upstream end wall of the first tubular element to the downstream end of the second tubular element. The continuous cavity may have a uniform diameter along the entire length of the continuous cavity. The continuous cavity may be substantially empty. The continuous cavity may be formed from the first cavity and the second cavity.

The first tubular element may have a length greater than a length of the second tubular element. The first tubular element may have a length less than the length of the second tubular element. The first tubular element has a length substantially equal to a length of the second tubular element.

The first tubular element may have a length of at least about 10 percent of the length of the aerosol-generating article. The first tubular element may have a length of at least about 20 percent of the length of the aerosol-generating article. The first tubular element may have a length of at least about 30 percent of the length of the aerosol-generating article. The first tubular element may have a length of at least about 40 percent of the length of the aerosolgenerating article. The first tubular element may have a length of at least about 50 percent of the length of the aerosol-generating article. The first tubular element may have a length between about 10 millimetres and about 30 millimetres. The first tubular element may have a length between about 10 millimetres and about 25 millimetres. The first tubular element may have a length between about 10 millimetres and about 20 millimetres. The first tubular element may have a length between about 10 millimetres and about 15 millimetres.

The second tubular element may have a length of at least about 10 percent of the length of the aerosol-generating article. The second tubular element may have a length of at least about 20 percent of the length of the aerosol-generating article. The second tubular element may have a length of at least about 30 percent of the length of the aerosolgenerating article. The second tubular element may have a length of at least about 40 percent of the length of the aerosol-generating article. The second tubular element may have a length of at least about 50 percent of the length of the aerosol-generating article.

The second tubular element may have a length between about 10 millimetres and about 30 millimetres. The second tubular element may have a length between about 10 millimetres and about 25 millimetres. The second tubular element may have a length between about 10 millimetres and about 20 millimetres. The second tubular element may have a length between about 10 millimetres and about 15 millimetres.

The first opening may be radially aligned with the second opening. That is, at least 90 percent of the transverse cross-sectional area of the first opening overlaps with the transverse cross-sectional area of the second opening when viewed in the longitudinal direction. Advantageously, this may allow a heating element to be easily inserted through both the first opening and the second opening before contacting the aerosol-forming substrate. Alternatively, the first opening may be radially offset from the second opening. That is, the transverse cross-sectional area of the first opening does not overlap with the transverse cross-sectional area of the second opening when viewed in the longitudinal direction. Advantageously, radially offset openings may promote turbulent flow within the tubular element.

The first opening may be radially offset from the radially central axis of the first tubular element. That is, the geometric centre of the first opening does not coincide with the radially central axis of the first tubular element. When the first tubular element is positioned downstream of the aerosol-forming substrate and the first opening is radially offset from the radially central axis, aerosol that is generated in the aerosol-forming substrate, such as aerosol generated near the radially central axis, may be caused to move radially outwards as the aerosol is drawn through the aerosol-forming substrate. This is particularly advantageous in embodiments where the heat source is positioned in a radially central position within the aerosol-forming substrate, such as susceptor element or a heating element of a device that is inserted into the substrate during use. Typically, in such embodiments, the peripheral portion of the substrate is cooler than the radially central portion of the substrate. Thus, the aerosol may cool down as it moves radially outwards within the aerosol-forming substrate. This can be particularly beneficial during the first puff of a user on the article, when the majority of aerosol may be formed near the heat source. Such an offset first opening may also prevent a heat source, that is positioned radially centrally within the aerosol-forming substrate, from migrating downstream. This is particularly apparent when the upstream end wall of the first tubular element is in physical contact with the downstream end of the aerosol-forming substrate.

The first opening may be radially central. That is, the perimeter of the first opening may circumscribe the radially central axis of the first tubular element and the geometric centre of the first opening may coincide with the radially central axis of the first tubular element. For example, the first opening may be in a radially central position of the upstream end wall. The second opening may be radially central. That is, the perimeter of the second opening may circumscribe the radially central axis of the second tubular element and the geometric centre of the second opening may coincide with the radially central axis of the second tubular element. For example, the second opening may be in a radially central position of the second tubular element end wall.

The first opening may have an equivalent diameter equal to, or greater than, about 10 percent of the diameter of the upstream end wall. The first opening may have an equivalent diameter equal to, or greater than, about 20 percent of the diameter of the upstream end wall. The first opening may have an equivalent diameter equal to, or greater than, about 30 percent of the diameter of the upstream end wall. The first opening may have an equivalent diameter equal to, or greater than, about 40 percent of the diameter of the upstream end wall. The first opening may have an equivalent diameter equal to, or greater than, about 50 percent of the diameter of the upstream end wall.

The first opening may have an equivalent diameter of between about 1 millimetre and about 12 millimetres. The first opening may have an equivalent diameter of between about 1 millimetre and about 9 millimetres. The first opening may have an equivalent diameter of between about 1 millimetre and about 6 millimetres. Preferably, the first opening may have an equivalent diameter of between about 1 millimetre and about 3 millimetres. Advantageously, when the first tubular element is downstream of the aerosol-forming substrate, it has been found that an first opening having an equivalent diameter of between about 1 millimetres and about 3 millimetres provides a good compromise between providing the first tubular element with an acceptable RTD and the ability to prevent undesirable components of the aerosol-forming substrate migrating downstream. In particularly preferred embodiments, the first opening has an equivalent diameter of about 2.5 millimetres. The second opening may have an equivalent diameter equal to, or greater than, about 10 percent of the diameter of the second tubular element end wall. The second opening may have an equivalent diameter equal to, or greater than, about 20 percent of the diameter of the second tubular element end wall. The second opening may have an equivalent diameter equal to, or greater than, about 30 percent of the diameter of the second tubular element end wall. The second opening may have an equivalent diameter equal to, or greater than, about 40 percent of the diameter of the second tubular element end wall. The second opening may have an equivalent diameter equal to, or greater than, about 50 percent of the diameter of the second tubular element end wall.

The second opening may have an equivalent diameter of between about 1 millimetre and about 12 millimetres. The second opening may have an equivalent diameter of between about 1 millimetre and about 9 millimetres. The second opening may have an equivalent diameter of between about 1 millimetre and about 6 millimetres. Preferably, the second opening may have an equivalent diameter of between about 1 millimetre and about 3 millimetres. Advantageously, when the second tubular element is downstream of the aerosolforming substrate, having a second opening having an equivalent diameter of between about 1 millimetre and about 3 millimetres provides a good compromise between providing the second tubular element with an acceptable RTD and filtering undesirable volatile compounds before the aerosol exits the downstream end of the aerosol-generating article. In particularly preferred embodiments, the second opening has an equivalent diameter of about 2.5 millimetres.

The first opening may have an equivalent diameter substantially equal to an equivalent diameter of the second opening. For example, both the first opening and the second opening may have an equivalent diameter of about 2.5 millimetres. The first opening may have an equivalent diameter less than an equivalent diameter of the second opening. For example, the first opening may have an equivalent diameter of about 2 millimetres and the second opening may have an equivalent diameter of about 4 millimetres. The first opening may have an equivalent diameter less than an equivalent diameter of the second opening. For example, the first opening may have an equivalent diameter of about 4 millimetres and the second opening may have an equivalent diameter of about 2 millimetres.

The first opening may have an equivalent diameter equal to, or greater than, 500 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 400 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 300 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 200 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 150 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 140 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 130 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 120 percent of an equivalent diameter of the second opening. The first opening may have an equivalent diameter equal to, or greater than, 110 percent of an equivalent diameter of the second opening.

The second opening may have an equivalent diameter equal to, or greater than, 500 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 400 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 300 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 200 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 150 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 140 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 130 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 120 percent of an equivalent diameter of the first opening. The second opening may have an equivalent diameter equal to, or greater than, 110 percent of an equivalent diameter of the first opening.

The upstream end wall may define a plurality of openings for allowing fluid communication between the interior of the first tubular element and the exterior of the first tubular element. The second tubular element end wall may define a plurality of openings for allowing fluid communication between the interior of the second tubular element and the exterior of the second tubular element. Advantageously, providing a plurality of openings, rather than a single opening, may allow each of the plurality of openings to have a small equivalent diameter whilst still providing an acceptable RTD.

The number of openings defined in the upstream end wall may be greater than the number of openings defined in the second tubular element end wall. The number of openings defined in the upstream end wall may be less than the number of openings defined in the second tubular element end wall.

The aerosol-generating article may comprise a front plug located upstream of the aerosol-forming substrate. Advantageously, such a front plug may prevent the aerosolforming substrate from egressing from the upstream end of the aerosol-generating article. The front plug may also assist locating the aerosol-forming substrate at a predetermined distance from the upstream end of the aerosol-generating article for optimum engagement with a heat source, such as a heating element. The front plug may also make it less likely for a consumer to mistakenly use the aerosol-generating article like a conventional cigarette and ignite the end of the aerosol-generating article.

The front plug may be the most upstream element of the aerosol-generating article. The front plug may be in physical contact with the upstream end of the aerosol-forming substrate.

The front plug may be penetrable by a heating element so that the heating element can contact or penetrate the aerosol-forming substrate. In such embodiments, the aerosolforming substrate may shrink into contact with a heating element during an aerosolgenerating phase. The aerosol-forming substrate may also shrink such that its contact with an outer wrapper of the aerosol-generating article is reduced. Without a front plug, the withdrawal of the heating element from the rod may also result in the withdrawal of the aerosol-forming substrate due to increased adhesion of the aerosol-forming substrate with the heating element coupled with decreased adhesion of the aerosol-forming substrate with the cigarette paper. However, the front plug may facilitate removal or extraction of the heating element from the rod by restricting the movement of the aerosol-forming substrate towards the distal end of the rod. The front plug may block the passage of the aerosol-forming substrate and therefore prevent the aerosol-forming substrate from being withdrawn from the aerosol-generating article.

The front plug may be made from a filter material that allows air to be drawn through the front plug. This may allow a consumer to draw air through the aerosol-generating article via the front plug. The front plug may conveniently be formed from the same material as a conventional mouthpiece filter. For example, the front plug may be formed from a length of cellulose acetate tow. Permeability of the front plug may be varied to help control resistance to draw through the aerosol-generating article. Alternatively, the front plug may be formed from a material that is not permeable to air. In such embodiments, the aerosol-generating article may be configured such that air flows into the aerosol-forming substrate through a sidewall of the aerosol-generating article upstream of the aerosol-forming substrate.

The front plug may be a hollow element, for example the front plug may be in the form of a tube. The front plug may be made from cellulose acetate, for example the front plug may be a hollow cellulose acetate tube.

The front plug may comprise one or more materials selected from the group comprising ceramic, polymer, biopolymer, metal, zeolite, paper, cardboard, inert material, and inorganic material. The front plug has a diameter that is approximately equal to the diameter of the aerosol-generating article. Preferably, the front plug has a diameter between about 5 millimetres and about 10 millimetres. The front plug may have a length of the frontplug is between about 1 millimetre and about 10 millimetres, between about 2 millimetres and about 8 millimetres, between about 4 millimetres and about 8 millimetres. The front plug may be cylindrical and may have a length of at least 2 millimetres in order to facilitate assembly of an aerosol-generating article, preferably at least 3 millimetres or at least 4 millimetres. The front plug may have a length of about 5 millimetres. Advantageously, a longer plug may also provide an improved cleaning effect as there is a greater amount of the front plug material available for wiping the heating element as the heating element is withdrawn from the plug.

One or both of the first tubular element and the second tubular element may comprise a hydrophobic coating. The first tubular element may comprises a hydrophobic coating. At least a portion of the first tubular element may comprise a hydrophobic coating. The second tubular element may comprise a hydrophobic coating. At least a portion of the second tubular element may comprise a hydrophobic coating. As volatile compounds and air cool as they pass through the tubular element. The volatile compounds may condense on one or both of the upstream and second tubular element. Advantageously, a hydrophobic coating may prevent deterioration of the structural integrity of the first tubular element and the second tubular element due to the condensed matter.

The upstream end wall of the first tubular element may comprise a hydrophobic coating. The second tubular element end wall of the second tubular element may comprise a hydrophobic coating. The first cavity of the first tubular element may comprise a hydrophobic coating. The second cavity of the second tubular element may comprise a hydrophobic coating.

As used herein, 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.

The hydrophobic coating may have a Cobb water absorption (ISO535:1991) value (at 60 seconds) of less than about 40 g/m2, less than about 35 g/m2, less than about 30 g/m2, or less than about 25 g/m2.

The hydrophobic coating may have a water contact angle of at least about 90 degrees, at least about 95 degrees, at least about 100 degrees, at least about 110 degrees, at least about 120 degrees, at least about 130 degrees at least about 140 degrees, at least about 150 degrees, at least about 160 degrees, or at least about 170 degrees. Hydrophobicity is determined by utilizing the TAPPI T558 om-97 test and the result is presented as an interfacial contact angle and reported in “degrees” and can range from near zero degrees to near 180 degrees. Where no contact angle is specified along with the term hydrophobic, the water contact angle is at least 90 degrees. One or both of the first tubular element and the second tubular element may be formed from a paper material, such as paper, paperboard or cardboard. One or both of the first tubular element and the second tubular element may be formed from a plurality of overlapping paper layers, such as a plurality of parallel wound paper layers or a plurality of spirally wound paper layers. Forming one or both of the first tubular element and the second tubular element from a plurality of overlapping paper layers can help to improve the tubular element’s resistance to collapse or deformation.

Where one or both of the first tubular element and the second tubular element is formed from a paper material, the paper material may have a basis weight of at least about 90 grams per square metre. The paper material may have a basis weight of less than about 300 grams per square metre. The paper material may have a basis weight of from about 100 to about 200 grams per square metre. Advantageously, providing one or both of the first tubular element and the second tubular element with such wall basis weight can help to improve the tubular element’s resistance to collapse or deformation.

The first tubular element may be formed from first material. The second tubular element may be formed from a second material. The basis weight of the first material may be greater than the basis weight of the second material. The basis weight of the first material may be less than the basis weight of the second material. The first material and the second material may be the same material, for example cardboard, but may have a different basis weight. The first material may be any of the material described above. The second material may be any of the material described above.

The first tubular element may have a tubular wall thickness of at least about 0.1 millimetres, more preferably at least about 0.2 millimetres. The first tubular element may have a tubular wall thickness of less than about 1.5 millimetres, preferably less than about 1.25 millimetres. In a preferred embodiment, the first tubular element has a tubular wall thickness of less than about 1 millimetre. The first tubular element therefore preferably has a tubular wall thickness of between about 0.1 millimetres and about 1.5 millimetres, or between about 0.2 millimetres and about 1.25 millimetres, or between about 0.5 millimetres and about 1 millimetre. In some embodiments, the first tubular element may have a tubular wall thickness of between about 0.15 millimetres and about 0.6 millimetres. Advantageously, providing the first tubular element with such a tubular wall thickness can help to improve the first tubular element’s resistance to collapse or deformation.

As used herein, the term “tubular wall thickness” refers to the thickness of the tubular wall, as measured in the radial direction, extending from the upstream end of a tubular element to the downstream end of the tubular element.

The second tubular element may have a tubular wall thickness of at least about 0.1 millimetres, more preferably at least about 0.2 millimetres. The second tubular element may have a tubular wall thickness of less than about 1.5 millimetres, preferably less than about 1.25 millimetres. In a preferred embodiment, the second tubular element has a tubular wall thickness of less than about 1 millimetre. The second tubular element therefore preferably has a tubular wall thickness of between about 0.1 millimetres and about 1.5 millimetres, or between about 0.2 millimetres and about 1.25 millimetres, or between about 0.5 millimetres and about 1 millimetre. In some embodiments, the second tubular element may have a tubular wall thickness of between about 0.15 millimetres and about 0.6 millimetres. Advantageously, providing the second tubular element with such a tubular wall thickness can help to improve the second tubular element’s resistance to collapse or deformation.

The tubular wall thickness of the first tubular element may be greater than a tubular wall thickness of the second tubular element. Alternatively, the tubular wall thickness of the first tubular element may be less than a tubular wall thickness of the second tubular element. Alternatively, the tubular wall thickness of the first tubular element may be substantially the same as the tubular wall thickness of the second tubular element.

The aerosol-generating article may comprise an outer wrapper circumscribing at least the first tubular element and the second tubular element. The outer wrapper may extend from the upstream end of the first tubular element to the downstream end of the second tubular element. The outer wrapper may define an outer surface of the aerosol-generating article. The outer wrapper may circumscribe at least the aerosol-forming substrate, the first tubular element and the second tubular element. The outer wrapper may circumscribe all of the plurality of elements of the aerosol-generating article which are assembled in the form of a rod.

The outer wrapper may be a tipping paper. The outer wrapper may be a paper wrapper or a non-paper wrapper. Suitable paper wrappers 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. In certain preferred embodiments, the outer wrapper may be formed of a laminate material comprising a plurality of layers. Preferably, the wrapper is formed of an aluminium co-laminated sheet. The use of a co-laminated sheet comprising aluminium advantageously prevents combustion of the outer wrapper in the event that the aerosol-forming substrate should be ignited, rather than heated in the intended manner.

The aerosol-generating article comprise a ventilation zone. Advantageously, this may increase the cooling of the air and volatile compounds within the interior of one or both of the upstream and second tubular element by drawing in cooler, external air. It may also increase the turbulence within the tubular elements, particularly where the ventilation zone causes air to be drawn into the tubular elements in a direction transverse to the longitudinal axis of the tubular elements. The ventilation zone may be positioned between an upstream end of the aerosolgenerating article and a downstream end of the aerosol-generating article. The ventilation zone may be positioned downstream of the aerosol-forming substrate. The ventilation zone may be positioned downstream of the first tubular element. Alternatively, the ventilation zone may be positioned upstream of the first tubular element. The ventilation zone may be positioned downstream of the second tubular element. Alternatively, the ventilation zone may be positioned upstream of the second tubular element.

As mentioned above, in embodiments the first tubular element and the second tubular element may be longitudinally spaced. The ventilation zone may be positioned downstream of the first tubular element and upstream of the second tubular element. The ventilation zone may be positioned between the downstream end of the first tubular element and the upstream end of the second tubular element. The ventilation zone may be positioned between the first tubular element and the second tubular element.

The ventilation zone may be positioned at a location along the first tubular element. The ventilation zone may be positioned at a location along the second tubular element. For example, the ventilation zone may be positioned longitudinally between the upstream end and the downstream end of the first tubular element or the second tubular element. Features of the ventilation zone are described below in respect of the aerosol-generating article. However, it will be appreciated that they may also apply to directly to the tubular elements themselves.

The ventilation zone may be located between about 5 millimetres and about 15 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall. The ventilation zone may be located at least 2 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, more preferably at least 3 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, even more preferably at least 5 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall.

The ventilation zone may be located less than 20 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, more preferably less than 15 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, even more preferably less than 10 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall.

The ventilation zone may be located between about 1 millimetres and about 10 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, more preferably between about 2 millimetres and about 8 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, even more preferably between about 3 millimetres and about 6 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall.

The ventilation zone may be located at least 1 millimetres the upstream end wall of the first tubular element or the second tubular element end wall, more preferably the ventilation zone is located at least 2 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, even more preferably the ventilation zone is located at least 3 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall.

The ventilation zone may be located less than 10 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, more preferably the ventilation zone may be located less than 8 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall, even more preferably the ventilation zone may be located less than 6 millimetres from the upstream end wall of the first tubular element or the second tubular element end wall.

The ventilation zone may comprise a plurality of perforations through the peripheral wall or tubular wall of one or more of the aerosol-generating article, the first tubular element and the second tubular element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. The ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed during manufacturing of the aerosol-generating article. Preferably, each circumferential row of perforations comprises from 8 to 30 perforations.

An aerosol-generating article in accordance with the present invention may have a ventilation level of at least about 5 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 aerosol-generating article may typically have a ventilation level of at least about 10 percent, preferably at least about 15 percent, more preferably at least about 20 percent.

In preferred embodiments, the aerosol-generating article has a ventilation level of at least about 25 percent. The aerosol-generating article preferably has a ventilation level of less than about 60 percent. The aerosol-generating article may have a ventilation level of less than or equal to about 45 percent. More preferably, the aerosol-generating article may have a ventilation level of less than or equal to about 40 percent, even more preferably less than or equal to about 35 percent. In a particularly preferred embodiments, the aerosol-generating article has a ventilation level of about 30 percent. The aerosol-generating article may have a ventilation level from about 20 percent to about 60 percent, preferably from about 20 percent to about 45 percent, more preferably from about 20 percent to about 40 percent The aerosolgenerating article may have a ventilation level from about 25 percent to about 60 percent, preferably from about 25 percent to about 45 percent, more preferably from about 25 percent to about 40 percent. In further embodiments, the aerosol-generating article has a ventilation level from about 30 percent to about 60 percent, preferably from about 30 percent to about 45 percent, more preferably from about 30 percent to about 40 percent. The aerosolgenerating article may have a ventilation level of between about 30 percent and about 60 percent. The aerosol-generating article may have a ventilation level of between about 40 percent and about 50 percent.

In some particularly preferred embodiments, the aerosol-generating article has a ventilation level from about 28 percent to about 42 percent. In some particularly preferred embodiments, the aerosol-generating article has a ventilation level of about 30 percent.

Embodiments where the ventilation zone is provided at a location along the first tubular element or second tubular element may provide a number of advantages. For example, and without wishing to be bound by theory, the inventors have found that the temperature drop caused by the admission of cooler, external air into the tubular element via the ventilation zone may have an advantageous effect on the nucleation and growth of aerosol particles.

The aerosol-generating article may comprise a susceptor element positioned in thermal contact within the aerosol-forming substrate. The susceptor element may be positioned within the aerosol-forming substrate. The susceptor element may be positioned within the aerosol-forming substrate. The susceptor element may be an elongate susceptor element. The susceptor element may extend longitudinally within the aerosol-forming substrate. The susceptor element may extend along a radially central axis of the aerosolforming substrate.

As used herein, the term “susceptor element” refers to a material that can convert electromagnetic energy into heat. When located within an alternating magnetic field, eddy currents induced in the susceptor element cause heating of the susceptor element. As the elongate susceptor element is located in thermal contact with the aerosol-forming substrate, the aerosol-forming 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 may be arranged substantially longitudinally within the aerosol-forming substrate. This means that the length dimension of the elongate susceptor element is arranged to be approximately parallel to the longitudinal direction of the aerosolforming substrate, for example within plus or minus 10 degrees of parallel to the longitudinal direction of the aerosol-forming substrate. In preferred embodiments, the elongate susceptor element may be positioned in a radially central position within the aerosol-forming substrate, and extend along the longitudinal axis of the aerosol-forming substate.

The susceptor element may extend from an upstream end of the aerosol-forming substrate to a downstream end of the aerosol-forming substrate. Preferably, the susceptor element extends all the way to a downstream end of the aerosol-forming substrate. The susceptor element may extend all the way to an upstream end of the aerosol-forming substrate. In particularly preferred embodiments, the susceptor element has substantially the same length as the aerosol-forming substrate, and extends from the upstream end of the aerosol-forming substrate to the downstream end of the aerosol-forming substrate.

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

The susceptor element preferably has a length from about 5 millimetres to about 15 millimetres, for example from about 6 millimetres to about 12 millimetres, or from about 8 millimetres to about 10 millimetres.

A ratio between the length of the susceptor element and the overall length of the aerosol-generating article may be from about 0.2 to about 0.35.

Preferably, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article is at least about 0.22, more preferably at least about 0.24, even more preferably at least about 0.26. A ratio between the length of the susceptor element and the overall length of the aerosol-generating article is preferably less than about 0.34, more preferably less than about 0.32, even more preferably less than about 0.3.

A ratio between the length of the susceptor element and the overall length of the aerosol-generating article may be from about 0.22 to about 0.34, more preferably from about 0.24 to about 0.34, even more preferably from about 0.26 to about 0.34. A ratio between the length of the susceptor element and the overall length of the aerosol-generating article may be from about 0.22 to about 0.32, more preferably from about 0.24 to about 0.32, even more preferably from about 0.26 to about 0.32. In further embodiments, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article is preferably from about 0.22 to about 0.3, more preferably from about 0.24 to about 0.3, even more preferably from about 0.26 to about 0.3.

In a particularly preferred embodiment, a ratio between the length of the susceptor element and the overall length of the aerosol-generating article is about 0.27. The susceptor element preferably has a width from about 1 millimetres to about 5 millimetres.

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

If the susceptor element has a constant cross-section, for example a circular crosssection, it has a preferable width or diameter from about 1 millimetre to about 5 millimetres.

If the susceptor element has the form of a strip or blade, the strip or blade preferably has a rectangular shape having a width of preferably from about 2 millimetres to about 8 millimetres, more preferably from about 3 millimetres to about 5 millimetres. By way of example, a susceptor element in the form of a strip of blade may have a width of about 4 millimetres.

If the susceptor element has the form of a strip or blade, the strip or blade preferably has a rectangular shape and a thickness from about 0.03 millimetres to about 0.15 millimetres, more preferably from about 0.05 millimetres to about 0.09 millimetres. By way of example, a susceptor element in the form of a strip of blade may have a thickness of about 0.07 millimetres.

In a preferred embodiment, the elongate susceptor element is in the form of a strip or blade, preferably has a rectangular shape, and has a thickness from about 55 micrometres to about 65 micrometres.

More preferably, the elongate susceptor element has a thickness from about 57 micrometres to about 63 micrometres. Even more preferably, the elongate susceptor element has a thickness from about 58 micrometres to about 62 micrometres. In a particularly preferred embodiment, the elongate susceptor element has a thickness of about 60 micrometres.

Preferably, the elongate susceptor element has a length which is the same or shorter than the length of the aerosol-forming substrate. Preferably, the elongate susceptor element has a same length as the aerosol-forming substrate.

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-forming 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. Preferred susceptor elements may be formed from 400 series stainless steels, for example grade 410, or grade 420, or grade 430 stainless steel. Different materials will dissipate different amounts of energy when positioned within electromagnetic fields having similar values of frequency and field strength.

Thus, parameters of the susceptor element such as material type, length, width, and thickness may all be altered to provide a desired power dissipation within a known electromagnetic field. Preferred susceptor elements may be heated to a temperature in excess of 250 degrees Celsius.

Suitable susceptor elements may comprise a non-metallic core with a metal layer disposed on the non-metallic core, for example metallic tracks formed on a surface of a ceramic core. A susceptor element may have a protective external layer, for example a protective ceramic layer or protective glass layer encapsulating the susceptor element. The susceptor element may comprise a protective coating formed by a glass, a ceramic, or an inert metal, formed over a core of susceptor element material.

The susceptor element may be a multi-material susceptor element and may comprise a first susceptor element material and a second susceptor element material. The first susceptor element material is disposed in intimate physical contact with the second susceptor element material. The second susceptor element material preferably has a Curie temperature that is lower than 500 degrees Celsius. The first susceptor element material is preferably used primarily to heat the susceptor element when the susceptor element is placed in a fluctuating electromagnetic field. Any suitable material may be used. For example the first susceptor element material may be aluminium, or may be a ferrous material such as a stainless steel. The second susceptor element material is preferably used primarily to indicate when the susceptor element has reached a specific temperature, that temperature being the Curie temperature of the second susceptor element material. The Curie temperature of the second susceptor element material can be used to regulate the temperature of the entire susceptor element during operation. Thus, the Curie temperature of the second susceptor element material should be below the ignition point of the aerosolforming substrate. Suitable materials for the second susceptor element material may include nickel and certain nickel alloys.

By providing a susceptor element having at least a first and a second susceptor element material, with either the second susceptor element material having a Curie temperature and the first susceptor element material not having a Curie temperature, or first and second susceptor element materials having first and second Curie temperatures distinct from one another, the heating of the aerosol-forming substrate and the temperature control of the heating may be separated. The first susceptor element material is preferably a magnetic material having a Curie temperature that is above 500 degrees Celsius. It is desirable from the point of view of heating efficiency that the Curie temperature of the first susceptor element material is above any maximum temperature that the susceptor element should be capable of being heated to. The second Curie temperature may preferably be selected to be lower than 400 degrees Celsius, preferably lower than 380 degrees Celsius, or lower than 360 degrees Celsius. It is preferable that the second susceptor element material is a magnetic material selected to have a second Curie temperature that is substantially the same as a desired maximum heating temperature. That is, it is preferable that the second Curie temperature is approximately the same as the temperature that the susceptor element should be heated to in order to generate an aerosol from the aerosolforming substrate. The second Curie temperature may, for example, be within the range of 200 degrees Celsius to 400 degrees Celsius, or between 250 degrees Celsius and 360 degrees Celsius. The second Curie temperature of the second susceptor element material may, for example, be selected such that, upon being heated by a susceptor element that is at a temperature equal to the second Curie temperature, an overall average temperature of the aerosol-forming substrate does not exceed 240 degrees Celsius.

The aerosol-forming substrate may have a length of between about 10 millimetres and about 15 millimetres. The aerosol-forming substrate may a length of between about 11 millimetres and about 12 millimetres.

The aerosol-forming substrate may comprise tobacco cut filler.

The aerosol-forming substrate may comprise tobacco cast leaf.

The aerosol-forming substrate may be a gathered sheet of homogenised tobacco material. The gathered sheet of homogenised tobacco material may extend across substantially the entire transverse cross-sectional area of the rod.

The gathered sheet of homogenised tobacco material may have a grammage 100 g/m² and about 300 g/m².

The gathered sheet of homogenised tobacco material may have a thickness of between 50 pm and about 300 pm

The gathered sheet of homogenised tobacco material may be a crimped and gathered sheet of homogenised tobacco material. The crimped and gathered sheet of homogenised tobacco material may have a plurality of ridges or corrugations substantially parallel to the longitudinal axis of the rod.

In certain preferred embodiments, the aerosol-forming 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-forming 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. For example, the homogenised plant material may be in the form of one or more sheets. As used herein, the term “sheet” describes a laminar element having a width and length 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 strands may be formed in situ within the aerosol-forming substrate as a result of the splitting or cracking of a sheet of homogenised plant material during formation of the aerosol-forming substrate, for example, as a result of crimping. The strands of homogenised plant material within the aerosol-forming substrate may be separate from each other. At least some strands of homogenised plant material within the aerosol-forming substrate may be at least partially connected to an adjacent strand or strands along the length of the strands. For example, adjacent strands may be connected by one or more fibres. This may occur, for example, where the strands have been formed due to the splitting of a sheet of homogenised plant material during production of the aerosol-forming substrate, as described above.

Preferably, the aerosol-forming substrate is in the form of one or more sheets of homogenised plant material. The one or more sheets of homogenised plant material may be produced by a casting process. The one or more sheets of homogenised plant material may be produced by a paper-making process. The one or more sheets as described herein may each individually have a thickness of between 100 micrometres and 600 micrometres, preferably between 150 micrometres and 300 micrometres, and most preferably between 200 micrometres and 250 micrometres. Individual thickness refers to the thickness of the individual sheet, whereas combined thickness refers to the total thickness of all sheets that make up the aerosol-forming substrate. For example, if the aerosol-forming substrate is formed from two individual sheets, then the combined thickness is the sum of the thickness of the two individual sheets or the measured thickness of the two sheets where the two sheets are stacked in the aerosol-forming substrate.

The one or more sheets as described herein may each individually have a grammage of between about 100 g/m² and about 300 g/m². The one or more sheets as described herein may each individually have a density of from about 0.3 g/cm³ to about 1.3 g/cm³, and preferably from about 0.7 g/cm³ to about 1.0 g/cm³.

In embodiments in which the aerosol-forming substrate comprises one or more sheets of homogenised plant material, the sheets are preferably in the form of one or more gathered sheets. As used herein, the term “gathered” denotes that the sheet of homogenised plant material is convoluted, folded, or otherwise compressed or constricted substantially transversely to the cylindrical axis of a plug or a rod.

The one or more sheets of homogenised plant material may be gathered transversely relative to the longitudinal axis thereof and circumscribed with a wrapper to form a continuous rod or a plug.

The one or more sheets of homogenised plant material may advantageously be crimped or similarly treated. As used herein, the term “crimped” denotes a sheet having a plurality of substantially parallel ridges or corrugations. Alternatively or in addition to being crimped, the one or more sheets of homogenised plant material may be embossed, debossed, perforated or otherwise deformed to provide texture on one or both sides of the sheet.

Preferably, each sheet of homogenised plant material may be crimped such that it has a plurality of ridges or corrugations substantially parallel to the longitudinal axis of the rod. This treatment advantageously facilitates gathering of the crimped sheet of homogenised plant material to form the aerosol-forming substrate. Preferably, the one or more sheets of homogenised plant material may be gathered. It will be appreciated that crimped sheets of homogenised plant material may alternatively or in addition have a plurality of substantially parallel ridges or corrugations disposed at an acute or obtuse angle to the longitudinal axis of the rod. The sheet may be crimped to such an extent that the integrity of the sheet becomes disrupted at the plurality of parallel ridges or corrugations causing separation of the material, and results in the formation of shreds, strands or strips of homogenised plant material.

The one or more sheets of homogenised plant material may be cut into strands as referred to above. The aerosol-forming substrate may comprise a plurality of strands of the homogenised plant material. The strands may be used to form a plug. Typically, the width of such strands is about 5 millimetres, or about 4 millimetres, or about 3 millimetres, or about 2 millimetres or less. The length of the strands may be greater than about 5 millimetres, between about 5 millimetres to about 15 millimetres, about 8 millimetres to about 12 millimetres, or about 12 millimetres. Preferably, the strands have substantially the same length as each other. The length of the strands may be determined by the manufacturing process whereby a rod is cut into shorter plugs and the length of the strands corresponds to the length of the plug. The strands may be fragile which may result in breakage especially during transit. In such cases, the length of some of the strands may be less than the length of the plug.

The plurality of strands preferably extend substantially longitudinally along the length of the aerosol-forming substrate, aligned with the longitudinal axis. Preferably, the plurality of strands are therefore aligned substantially parallel to each other.

The homogenised plant material may comprise up to about 95 percent by weight of plant particles, on a dry weight basis. Preferably, the homogenised plant material comprises up to about 90 percent by weight of plant particles, more preferably up to about 80 percent by weight of plant particles, more preferably up to about 70 percent by weight of plant particles, more preferably up to about 60 percent by weight of plant particles, more preferably up to about 50 percent by weight of plant particles, on a dry weight basis.

For example, the homogenised plant material may comprise between about 2.5 percent and about 95 percent by weight of plant particles, or about 5 percent and about 90 percent by weight of plant particles, or between about 10 percent and about 80 percent by weight of plant particles, or between about 15 percent and about 70 percent by weight of plant particles, or between about 20 percent and about 60 percent by weight of plant particles, or between about 30 percent and about 50 percent by weight of plant particles, on a dry weight basis.

The homogenised plant material may be a homogenised tobacco material comprising tobacco particles. Sheets of homogenised tobacco material for use in such embodiments may have a tobacco content of at least about 40 percent by weight on a dry weight basis, more preferably of at least about 50 percent by weight on a dry weight basis more preferably at least about 70 percent by weight on a dry weight basis and most preferably at least about 90 percent by weight on a dry weight basis.

The term “tobacco particles” describes particles of any plant member of the genus Nicotiana. The term “tobacco particles” encompasses ground or powdered tobacco leaf lamina, ground or powdered tobacco leaf stems, tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the treating, handling and shipping of tobacco. In a preferred embodiment, the tobacco particles are substantially all derived from tobacco leaf lamina. By contrast, isolated nicotine and nicotine salts are compounds derived from tobacco but are not considered tobacco particles for purposes of the invention and are not included in the percentage of particulate plant material.

The tobacco particles may be prepared from one or more varieties of tobacco plants. Any type of tobacco may be used in a blend. Examples of tobacco types that may be used include, but are not limited to, sun-cured tobacco, flue-cured tobacco, Burley tobacco, Maryland tobacco, Oriental tobacco, Virginia tobacco, and other speciality tobaccos. Flue-curing is a method of curing tobacco, which is particularly used with Virginia tobaccos. During the flue-curing process, heated air is circulated through densely packed tobacco. During a first stage, the tobacco leaves turn yellow and wilt. During a second stage, the laminae of the leaves are completely dried. During a third stage, the leaf stems are completely dried.

Burley tobacco plays a significant role in many tobacco blends. Burley tobacco has a distinctive flavour and aroma and also has an ability to absorb large amounts of casing.

Oriental is a type of tobacco which has small leaves, and high aromatic qualities. However, Oriental tobacco has a milder flavour than, for example, Burley. Generally, therefore, Oriental tobacco is used in relatively small proportions in tobacco blends.

Kasturi, Madura and Jatim are subtypes of sun-cured tobacco that can be used. Preferably, Kasturi tobacco and flue-cured tobacco may be used in a blend to produce the tobacco particles. Accordingly, the tobacco particles in the particulate plant material may comprise a blend of Kasturi tobacco and flue-cured tobacco.

The tobacco particles may have a nicotine content of at least about 2.5 percent by weight, based on dry weight. More preferably, the tobacco particles may have a nicotine content of at least about 3 percent, even more preferably at least about 3.2 percent, even more preferably at least about 3.5 percent, most preferably at least about 4 percent by weight, based on dry weight.

The homogenised plant material may comprise tobacco particles in combination with non-tobacco plant flavour particles. Preferably, the non-tobacco plant flavour particles are selected from one or more of: ginger particles, rosemary particles, eucalyptus particles, clove particles and star anise particles. Preferably, in such embodiments, the homogenised plant material comprises at least about 2.5 percent by weight of the non-tobacco plant flavour particles, on a dry weight basis, with the remainder of the plant particles being tobacco particles. Preferably, the homogenised plant material comprises at least about 4 percent by weight of non-tobacco plant flavour particles, more preferably at least about 6 percent by weight of non-tobacco plant flavour particles, more preferably at least about 8 percent by weight of non-tobacco plant flavour particles and more preferably at least about 10 percent by weight of non-tobacco plant flavour particles, on a dry weight basis. Preferably, the homogenised plant material comprises up to about 20 percent by weight of non-tobacco plant flavour particles, more preferably up to about 18 percent by weight of non-tobacco plant flavour particles, more preferably up to about 16 percent by weight of non-tobacco plant flavour particles.

The weight ratio of the non-tobacco plant flavour particles and the tobacco particles in the particulate plant material forming the homogenised plant material may vary depending on the desired flavour characteristics and composition of the aerosol produced from the aerosol-forming substrate during use. Preferably, the homogenised plant material comprises at least a 1 :30 weight ratio of non-tobacco plant flavour particles to tobacco particles, more preferably at least a 1 :20 weight ratio of non-tobacco plant flavour particles to tobacco particles, more preferably at least a 1 :10 weight ratio of non-tobacco plant flavour particles to tobacco particles and most preferably at least a 1 :5 weight ratio of non-tobacco plant flavour particles to tobacco particles, on a dry weight basis.

The homogenised plant material may comprise cannabis particles. The term “cannabis particles” refers to particles of a cannabis plant, such as the species Cannabis sativa, Cannabis indica, and Cannabis ruderalis.

The homogenised plant material preferably comprises no more than 95 percent by weight of the particulate plant material, on a dry weight basis. The particulate plant material is therefore typically combined with one or more other components to form the homogenised plant material.

The homogenised plant material may further comprise a binder to alter the mechanical properties of the particulate plant material, wherein the binder is included in the homogenised plant material during manufacturing as described herein. Suitable exogenous binders would be known to the skilled person and include but are not limited to: gums such as, for example, guar gum, xanthan gum, arabic gum and locust bean gum; cellulosic binders such as, for example, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose and ethyl cellulose; polysaccharides such as, for example, starches, organic acids, such as alginic acid, conjugate base salts of organic acids, such as sodium-alginate, agar and pectins; and combinations thereof. Preferably, the binder comprises guar gum.

The binder may be present in an amount of from about 1 percent to about 10 percent by weight, based on the dry weight of the homogenised plant material, preferably in an amount of from about 2 percent to about 5 percent by weight, based on the dry weight of the homogenised plant material.

The homogenised plant material may further comprise one or more lipids to facilitate the diffusivity of volatile components (for example, aerosol formers, gingerols and nicotine), wherein the lipid is included in the homogenised plant material during manufacturing as described herein. Suitable lipids for inclusion in the homogenised plant material include, but are not limited to: medium-chain triglycerides, cocoa butter, palm oil, palm kernel oil, mango oil, shea butter, soybean oil, cottonseed oil, coconut oil, hydrogenated coconut oil, candellila wax, carnauba wax, shellac, sunflower wax, sunflower oil, rice bran, and Revel A; and combinations thereof.

The homogenised plant material may further comprise a pH modifier. The homogenised plant material may further comprise fibres to alter the mechanical properties of the homogenised plant material, wherein the fibres are included in the homogenised plant material during manufacturing as described herein. Suitable exogenous fibres for inclusion in the homogenised plant material are known in the art and include fibres formed from non-tobacco material and non- ginger material, including but not limited to: cellulose fibres; soft-wood fibres; hard-wood fibres; jute fibres and combinations thereof. Exogenous fibres derived from tobacco and/or ginger can also be added. Any fibres added to the homogenised plant material are not considered to form part of the “particulate plant material” as defined above. Prior to inclusion in the homogenised plant material, fibres may be treated by suitable processes known in the art including, but not limited to: mechanical pulping; refining; chemical pulping; bleaching; sulfate pulping; and combinations thereof. A fibre typically has a length greater than its width.

Suitable fibres typically have lengths of greater than 400 micrometres and less than or equal to 4 millimetres, preferably within the range of 0.7 millimetres to 4 millimetres. Preferably, the fibres are present in an amount of about 2 percent to about 15 percent by weight, most preferably at about 4 percent by weight, based on the dry weight of the substrate.

The aerosol-forming substrate, in particular the homogenised plant material, may further comprise one or more aerosol formers. Upon volatilisation, an aerosol former can convey other vaporised compounds released from the aerosol-forming substrate upon heating, such as nicotine and flavourants, in an aerosol. Suitable aerosol formers for inclusion in the homogenised plant material are known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, propylene glycol, 1 ,3-butanediol and glycerol; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

The aerosol-forming substrate, in particular the homogenised plant material, may have an aerosol former content of between about 5 percent and about 30 percent by weight on a dry weight basis, such as between about 10 percent and about 25 percent by weight on a dry weight basis, or between about 15 percent and about 20 percent by weight on a dry weight basis.

For example, if the substrate is intended for use in an aerosol-generating article for an electrically-operated aerosol-generating system having a heating element, it may preferably include an aerosol former content of between about 5 percent to about 30 percent by weight on a dry weight basis. If the substrate is intended for use in an aerosol-generating article for an electrically-operated aerosol-generating system having a heating element, the aerosol former is preferably glycerol. The aerosol-forming substrate, in particular the homogenised plant material, may have an aerosol former content of about 1 percent to about 5 percent by weight on a dry weight basis. For example, if the substrate is intended for use in an aerosol-generating article in which aerosol former is kept in a reservoir separate from the substrate, the substrate may have an aerosol former content of greater than 1 percent and less than about 5 percent. In such embodiments, the aerosol former is volatilised upon heating and a stream of the aerosol former is contacted with the aerosol-forming substrate so as to entrain the flavours from the aerosol-forming substrate in the aerosol.

The aerosol-forming substrate, in particular the homogenised plant material, may have an aerosol former content of about 30 percent by weight to about 45 percent by weight. This relatively high level of aerosol former is particularly suitable for aerosol-forming substrates that are intended to be heated at a temperature of less than 275 degrees Celsius. In such embodiments, the homogenised plant material preferably further comprises between about 2 percent by weight and about 10 percent by weight of cellulose ether, on a dry weight basis and between about 5 percent by weight and about 50 percent by weight of additional cellulose, on a dry weight basis. The use of the combination of cellulose ether and additional cellulose has been found to provide a particularly effective delivery of aerosol when used in an aerosol-forming substrate having an aerosol former content of between 30 percent by weight and 45 percent by weight.

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

As used herein, the term “additional cellulose” encompasses any cellulosic material incorporated into the homogenised plant material which does not derive from the nontobacco plant particles or tobacco particles provided in the homogenised plant material. The additional cellulose is therefore incorporated in the homogenised plant material in addition to the non-tobacco plant material or tobacco material, as a separate and distinct source of cellulose to any cellulose intrinsically provided within the non-tobacco plant particles or tobacco particles. The additional cellulose will typically derive from a different plant to the non-tobacco plant particles or tobacco particles. Preferably, the additional cellulose is in the form of an inert cellulosic material, which is sensorially inert and therefore does not substantially impact the organoleptic characteristics of the aerosol generated from the aerosol-forming substrate. For example, the additional cellulose is preferably a tasteless and odourless material.

The additional cellulose may comprise cellulose powder, cellulose fibres, or a combination thereof. The aerosol former may act as a humectant in the aerosol-forming substrate.

The wrapper circumscribing the rod of homogenised plant material 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. In certain preferred embodiments, the wrapper may be formed of a laminate material comprising a plurality of layers. Preferably, the wrapper is formed of an aluminium co-laminated sheet. The use of a co-laminated sheet comprising aluminium advantageously prevents combustion of the aerosol-forming substrate in the event that the aerosol-forming substrate should be ignited, rather than heated in the intended manner.

In some preferred embodiments, the aerosol-forming substrate comprises a gel composition that includes an alkaloid compound, or a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound. In particularly preferred embodiments, the aerosol-forming substrate comprises a gel composition that includes nicotine.

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

Advantageously, a stable gel composition comprising nicotine provides predictable composition form upon storage or transit from manufacture to the consumer. The stable gel composition comprising nicotine substantially maintains its shape. The stable gel composition comprising nicotine substantially does not release a liquid phase upon storage or transit from manufacture to the consumer. The stable gel composition comprising nicotine may provide for a simple consumable design. This consumable may not have to be designed to contain a liquid, thus a wider range of materials and container constructions may be contemplated.

The gel composition described herein may be combined with an aerosol-generating device to provide a nicotine aerosol to the lungs at inhalation or air flow rates that are within conventional smoking regime inhalation or air flow rates. The aerosol-generating device may continuously heat the gel composition. A consumer may take a plurality of inhalations or “puffs” where each “puff” delivers an amount of nicotine aerosol. The gel composition may be capable of delivering a high nicotine/low total particulate matter (TPM) aerosol to a consumer when heated, preferably in a continuous manner.

The phrase “stable gel phase” or “stable gel” refers to gel that substantially maintains its shape and mass when exposed to a variety of environmental conditions. The stable gel may not substantially release (sweat) or absorb water when exposed to a standard temperature and pressure while varying relative humidity from about 10 percent to about 60 percent. For example, the stable gel may substantially maintain its shape and mass when exposed to a standard temperature and pressure while varying relative humidity from about 10 percent to about 60 percent.

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

The term “alkaloid compound” refers to any one of a class of naturally occurring organic compounds that contain one or more basic nitrogen atoms. Generally, an alkaloid contains at least one nitrogen atom in an amine-type structure. This or another nitrogen atom in the molecule of the alkaloid compound can be active as a base in acid-base reactions. Most alkaloid compounds have one or more of their nitrogen atoms as part of a cyclic system, such as for example a heterocylic ring. In nature, alkaloid compounds are found primarily in plants, and are especially common in certain families of flowering plants. However, some alkaloid compounds are found in animal species and fungi. In this disclosure, the term “alkaloid compound” refers to both naturally derived alkaloid compounds and synthetically manufactured alkaloid compounds.

The gel composition may preferably include an alkaloid compound selected from the group consisting of nicotine, anatabine, and combinations thereof.

Preferably the gel composition includes nicotine.

The term “nicotine” refers to nicotine and nicotine derivatives such as free-base nicotine, nicotine salts and the like.

The term “cannabinoid compound” refers to any one of a class of naturally occurring compounds that are found in parts of the cannabis plant - namely the species Cannabis sativa, Cannabis indica, and Cannabis ruderalis. Cannabinoid compounds are especially concentrated in the female flower heads. Cannabinoid compounds naturally occurring in the cannabis plant include cannabidiol (CBD) and tetrahydrocannabinol (THC). In this disclosure, the term “cannabinoid compounds” is used to describe both naturally derived cannabinoid compounds and synthetically manufactured cannabinoid compounds.

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

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

The gel may preferably include cannabidiol (CBD).

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

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

The gel composition preferably includes about 0.5 percent by weight to about 10 percent by weight of an alkaloid compound, or about 0.5 percent by weight to about 10 percent by weight of a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound in a total amount from about 0.5 percent by weight to about 10 percent by weight. The gel composition may include about 0.5 percent by weight to about 5 percent by weight of an alkaloid compound, or about 0.5 percent by weight to about 5 percent by weight of a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound in a total amount from about 0.5 percent by weight to about 5 percent by weight. Preferably the gel composition includes about 1 percent by weight to about 3 percent by weight of an alkaloid compound, or about 1 percent by weight to about 3 percent by weight of a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound in a total amount from about 1 percent by weight to about 3 percent by weight. The gel composition may preferably include about 1.5 percent by weight to about 2.5 percent by weight of an alkaloid compound, or about 1.5 percent by weight to about 2.5 percent by weight of a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound in a total amount from about 1.5 percent by weight to about 2.5 percent by weight. The gel composition may preferably include about 2 percent by weight of an alkaloid compound, or about 2 percent by weight of a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound in a total amount of about 2 percent by weight. The alkaloid compound component of the gel formulation may be the most volatile component of the gel formulation. In some aspects water may be the most volatile component of the gel formulation and the alkaloid compound component of the gel formulation may be the second most volatile component of the gel formulation. The cannabinoid compound component of the gel formulation may be the most volatile component of the gel formulation. In some aspects water may be the most volatile component of the gel formulation and the alkaloid compound component of the gel formulation may be the second most volatile component of the gel formulation. Preferably nicotine is included in the gel compositions. The nicotine may be added to the composition in a free base form or a salt form. The gel composition includes about 0.5 percent by weight to about 10 percent by weight nicotine, or about 0.5 percent by weight to about 5 percent by weight nicotine. Preferably the gel composition includes about 1 percent by weight to about 3 percent by weight nicotine, or about 1.5 percent by weight to about 2.5 percent by weight nicotine, or about 2 percent by weight nicotine. The nicotine component of the gel formulation may be the most volatile component of the gel formulation. In some aspects water may be the most volatile component of the gel formulation and the nicotine component of the gel formulation may be the second most volatile component of the gel formulation.

The gel composition preferably includes an aerosol-former. Ideally the aerosol-former is substantially resistant to thermal degradation at the operating temperature of the associated aerosol-generating device. Suitable aerosol-formers include, but are not limited to: polyhydric alcohols, such as triethylene glycol, 1 , 3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Polyhydric alcohols or mixtures thereof, may be one or more of triethylene glycol, 1 , 3-butanediol and, glycerine (glycerol or propane-1 , 2, 3-triol) or polyethylene glycol. The aerosol-former is preferably glycerol.

The gel composition may include a majority of an aerosol-former. The gel composition may include a mixture of water and the aerosol-former where the aerosol-former forms a majority (by weight) of the gel composition. The aerosol-former may form at least about 50 percent by weight of the gel composition. The aerosol-former may form at least about 60 percent by weight or at least about 65 percent by weight or at least about 70 percent by weight of the gel composition. The aerosol-former may form about 70 percent by weight to about 80 percent by weight of the gel composition. The aerosol-former may form about 70 percent by weight to about 75 percent by weight of the gel composition.

The gel composition may include a majority of glycerol. The gel composition may include a mixture of water and the glycerol where the glycerol forms a majority (by weight) of the gel composition. The glycerol may form at least about 50 percent by weight of the gel composition. The glycerol may form at least about 60 percent by weight or at least about 65 percent by weight or at least about 70 percent by weight of the gel composition. The glycerol may form about 70 percent by weight to about 80 percent by weight of the gel composition. The glycerol may form about 70 percent by weight to about 75 percent by weight of the gel composition.

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. More preferably, the composition includes the gelling agents in a range from about 0.5 percent by weight to about 8 percent by weight. More preferably, the composition includes the gelling agents in a range from about 1 percent by weight to about 6 percent by weight. More preferably, the composition includes the gelling agents in a range from about 2 percent by weight to about 4 percent by weight. More preferably, the composition includes the gelling agents in a range 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 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.

Preferably, the gel composition comprises at least about 0.2 percent by weight hydrogen-bond crosslinking gelling agent. The gel composition preferably comprises at least about 0.2 percent by weight ionic crosslinking gelling agent. Most preferably, the gel composition comprises at least about 0.2 percent by weight hydrogen-bond crosslinking gelling agent and at least about 0.2 percent by weight ionic crosslinking gelling agent. The gel composition may comprise about 0.5 percent by weight to about 3 percent by weight hydrogen-bond crosslinking gelling agent and about 0.5 percent by weight to about 3 percent by weight ionic crosslinking gelling agent, or about 1 percent by weight to about 2 percent by weight hydrogen-bond crosslinking gelling agent and about 1 percent by weight to about 2 percent by weight ionic crosslinking gelling agent. The hydrogen-bond crosslinking gelling agent and ionic crosslinking gelling agent may be present in the gel composition in substantially equal amounts by weight.

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. Hydrogen bonding is a type of electrostatic dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.

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 gel composition preferably includes the hydrogen-bond crosslinking gelling agent in a range from about 0.3 percent by weight to about 5 percent by weight. Preferably the composition includes the hydrogen-bond crosslinking gelling agent in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the composition includes the hydrogen-bond crosslinking gelling agent in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include a galactomannan in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the galactomannan may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the galactomannan may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the galactomannan may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include a gelatin in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the gelatin may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the gelatin may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the gelatin may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include agarose in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the agarose may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the agarose may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the agarose may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include konjac gum in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the konjac gum may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the konjac gum may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the konjac gum may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include agar in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the agar may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the agar may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the agar may be in a range from about 1 percent by weight to about 2 percent by weight. The term “ionic crosslinking gelling agent” refers to a gelling agent that forms non- covalent crosslinking bonds or physical crosslinking bonds via ionic bonding. Ionic crosslinking involves the association of polymer chains by noncovalent interactions. A crosslinked network is formed when multivalent molecules of opposite charges electrostatically attract each other giving rise to a crosslinked polymeric network.

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 gel composition may include the ionic crosslinking gelling agent in a range from about 0.3 percent by weight to about 5 percent by weight. Preferably the composition includes the ionic crosslinking gelling agent in a range from about 0.5 percent by weight to about 3 percent by weight by weight. Preferably the composition includes the ionic crosslinking gelling agent in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include low acyl gellan in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the low acyl gellan may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the low acyl gellan may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the low acyl gellan may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include pectin in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the pectin may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the pectin may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the pectin may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include kappa carrageenan in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the kappa carrageenan may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the kappa carrageenan may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the kappa carrageenan may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include iota carrageenan in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the iota carrageenan may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the iota carrageenan may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the iota carrageenan may be in a range from about 1 percent by weight to about 2 percent by weight. The gel composition may include alginate in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the alginate may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the alginate may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the alginate may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include the hydrogen-bond crosslinking gelling agent and ionic crosslinking gelling agent in a ratio of about 3:1 to about 1 :3. Preferably the gel composition may include the hydrogen-bond crosslinking gelling agent and ionic crosslinking gelling agent in a ratio of about 2:1 to about 1 :2. Preferably the gel composition may include the hydrogen-bond crosslinking gelling agent and ionic crosslinking gelling agent in a ratio of about 1 :1.

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 degrees Celsius, 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. Preferably the viscosifying agent refers to a compound that when added homogeneously into a 25 degrees Celsius 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of 0.3 percent by weight, increases the viscosity to at least 50 cPs, preferably at least 200 cPs, preferably at least 500 cPs, preferably at least 1000 cPs at a shear rate of 0.1 s-1 , without leading to the formation of a gel, the mixture staying or remaining fluid. Preferably the viscosifying agent refers to a compound that when added homogeneously into a 25 degrees Celsius 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of 0.3 percent by weight, increases the viscosity at least 2 times, or at least 5 times, or at least 10 times, or at least 100 times higher than before addition, at a shear rate of 0.1 s-1 , without leading to the formation of a gel, the mixture staying or remaining fluid.

The viscosity values recited herein can be measured using a Brookfield RVT viscometer rotating a disc type RV#2 spindle at 25 degrees Celsius at a speed of 6 revolutions per minute (rpm).

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

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

The gel composition may include xanthan gum in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the xanthan gum may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the xanthan gum may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the xanthan gum may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include carboxymethyl-cellulose in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the carboxymethyl-cellulose may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the carboxymethyl-cellulose may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the carboxymethyl-cellulose may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include microcrystalline cellulose in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the microcrystalline cellulose may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the microcrystalline cellulose may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the microcrystalline cellulose may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include methyl cellulose in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the methyl cellulose may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the methyl cellulose may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the methyl cellulose may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include gum Arabic in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the gum Arabic may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the gum Arabic may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the gum Arabic may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include guar gum in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the guar gum may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the guar gum may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the guar gum may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include lambda carrageenan in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the lambda carrageenan may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the lambda carrageenan may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the lambda carrageenan may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include starch in a range from about 0.2 percent by weight to about 5 percent by weight. Preferably the starch may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the starch may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the starch may be in a range from about 1 percent by weight to about 2 percent by weight.

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. The carboxylic acid may include a ketone group. Preferably the carboxylic acid may include a ketone group having less than about 10 carbon atoms, or less than about 6 carbon atoms or less than about 4 carbon atoms, such as levulinic acid or lactic acid. Preferably this carboxylic acid has three carbon atoms (such as lactic acid). Lactic acid surprisingly improves the stability of the gel composition even over similar carboxylic acids. The carboxylic acid may assist in the gel formation. The carboxylic acid may reduce variation of the alkaloid compound concentration, or the cannabinoid compound concentration, or both the alkaloid compound concentration and the cannabinoid compound within the gel composition during storage. The carboxylic acid may reduce variation of the nicotine concentration within the gel composition during storage.

The gel composition may include a carboxylic acid in a range from about 0.1 percent by weight to about 5 percent by weight. Preferably the carboxylic acid may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the carboxylic acid may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the carboxylic acid may be in a range from about 1 percent by weight to about 2 percent by weight. The gel composition may include lactic acid in a range from about 0.1 percent by weight to about 5 percent by weight. Preferably the lactic acid may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the lactic acid may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the lactic acid may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition may include levulinic acid in a range from about 0.1 percent by weight to about 5 percent by weight. Preferably the levulinic acid may be in a range from about 0.5 percent by weight to about 3 percent by weight. Preferably the levulinic acid may be in a range from about 0.5 percent by weight to about 2 percent by weight. Preferably the levulinic acid may be in a range from about 1 percent by weight to about 2 percent by weight.

The gel composition preferably comprises some water. The gel composition is more stable when the composition comprises some water. Preferably the gel composition comprises at least about 1 percent by weight, or at least about 2 percent by weight, or at least about 5 percent by weight of water. Preferably the gel composition comprises at least about 10 percent by weight or at least about 15 percent by weight water.

Preferably the gel composition comprises between about 8 percent by weight to about 32 percent by weight water. Preferably the gel composition comprises from about 15 percent by weight to about 25 percent by weight water. Preferably the gel composition comprises from about 18 percent by weight to about 22 percent by weight water. Preferably the gel composition comprises about 20 percent by weight water.

Preferably, the aerosol-forming substrate comprises between about 150 mg and about 350 mg of the gel composition.

Preferably, in embodiments comprising a gel composition, the aerosol-forming substrate comprises a porous medium loaded with the gel composition. Advantages of a porous medium loaded with the gel composition is that the gel composition is retained within the porous medium, and this may aid manufacturing, storage or transport of the gel composition. It may assist in keeping the desired shape of the gel composition, especially during manufacture, transport, or use.

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.

The porous medium may be any suitable porous material able to hold or retain the gel composition. Ideally the porous medium can allow the gel composition to move within it. In specific embodiments the porous medium comprises natural materials, synthetic, or semisynthetic, or a combination thereof. In specific embodiments the porous medium comprises sheet material, foam, or fibres, for example loose fibres; or a combination thereof. In specific embodiments the porous medium comprises a woven, non-woven, or extruded material, or combinations thereof. Preferably the porous medium comprises, cotton, paper, viscose, PLA, or cellulose acetate, of combinations thereof. Preferably the porous medium comprises a sheet material, for example, cotton or cellulose acetate. In a particularly preferred embodiment, the porous medium comprises a sheet made from cotton fibres.

The porous medium may be crimped or shredded. In preferred embodiments, the porous medium is crimped. In alternative embodiments the porous medium comprises shredded porous medium. The crimping or shredding process can be before or after loading with the gel composition.

Crimping of the sheet material has the benefit of improving the structure to allow passageways through the structure. The passageways though the crimped sheet material assist in loading up gel, retaining gel and also for fluid to pass through the crimped sheet material. Therefore there are advantages of using crimped sheet material as the porous medium.

Shredding gives a high surface area to volume ratio to the medium thus able to absorb gel easily.

In some embodiments the sheet material is a composite material. Preferably the sheet material is porous. The sheet material may aid manufacture of the tubular element comprising a gel. The sheet material may aid introducing an active agent to the tubular element comprising a gel. The sheet material may help stabilise the structure of the tubular element comprising a gel. The sheet material may assist transport or storage of the gel. Using a sheet material enables, or aids, adding structure to the porous medium for example by crimping of the sheet material.

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

The thread may be loaded with gel by any known means. The thread may be simply coated with gel, or the thread may be impregnated with gel. In the manufacture, the threads may be impregnated with gel and stored ready for use to be included in the assembly of a tubular element.

Preferably, in embodiments in which the first element comprises a gel composition, as described above, the tubular element has a length of less than 10 millimetres. The use of such a relatively short tubular element in combination with a gel composition may optimise the delivery of aerosol to the consumer.

The aerosol-generating article may comprise a capsule. The aerosol-forming substrate may be disposed within the capsule. During use, a consumer may rupture the capsule and draw on the aerosol-generating article, which causes the capsule to move within the aerosol-generating article and release the aerosol-forming substrate to form an aerosol that can be inhaled and delivered to the consumer’s lungs. As used herein, the term “rupture” refers to providing at least one opening in the capsule for allowing the aerosol-forming substrate within the capsule to exit the capsule. For example, a consumer may insert a rupturing element through the distal end of the aerosol-generating article to rupture the capsule. As another example, the capsule may be ruptured by the consumer exerting a force on the capsule, such as with their fingers.

The capsule may comprise a capsule shell for encapsulating the aerosol-forming substrate. The capsule may be any suitable pharmaceutical capsule, such as a hard-shelled capsule. The capsule shell may be manufactured from gelling agents such as gelatin and/or polysaccharides. The capsule shell may be formed from hydroxypropyl methyl cellulose (HPMC). The capsule shell may comprise plasticizers, such as glycerin or sorbitol.

As used herein, the term “pharmaceutically active ingredient” refers to an ingredient that alters one or more chemical or physiological functions of a cell, tissue, organ, or organism.

The aerosol-forming substrate disposed within the capsule may be a dry powder. The dry powder may comprise a pharmaceutically active ingredient. The pharmaceutically active ingredient may be nicotine.

According to an aspect of the invention, there is provided an electrically heated aerosol-generating system comprising an aerosol-generating article as described herein and an aerosol-generating device comprising an electrical element for heating the aerosolforming substrate.

The aerosol-generating device may comprise a power supply. The power supply may be configured to supply power to the electrical element. The power supply may be any suitable power supply, for example a DC voltage source such as a battery. In one embodiment, the power supply is a Lithium-ion battery. Alternatively, the power supply may be a Nickel-metal hydride battery, a Nickel cadmium battery, or a Lithium based battery, for example a Lithium-Cobalt, a Lithium-lron-Phosphate, Lithium Titanate or a Lithium-Polymer battery.

The aerosol-generating device may comprise a cavity for receiving the aerosolgenerating article.

The electrical element may be a heating element. The electrical element may be arranged inside or around the cavity of the aerosol-generating device. The electrical element may be an inductor, such as an induction coil.

The aerosol-generating device may comprise an internal heating element, for example a pin or a blade that is inserted for use at least partly into the aerosol-forming substrate. The internal heating element may be configured to be inserted into a radially central position of the aerosol-forming substrate. The aerosol-generating device may include an external heating element positioned around a perimeter of the cavity of the aerosol-generating device. An external heating element may take any suitable form. For example, an external heating element may take the form of one or more flexible heating foils on a dielectric substrate, such as polyimide. The flexible heating foils can be shaped to conform to the perimeter of the cavity. Alternatively, an external heating element may take the form of a metallic grid or grids, a flexible printed circuit board, a moulded interconnect device (MID), ceramic heating element, flexible carbon fibre heating element or may be formed using a coating technique, such as plasma vapour deposition, on a suitable shaped substrate.

It will be appreciated that any features described with reference to one aspect of the present invention, or disclosure, are equally applicable to any other aspect of the invention, or disclosure.

The invention is defined in the claims. However, 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 comprising a plurality of elements assembled in the form of a rod, the plurality of elements comprising: an aerosol-forming substrate; a first tubular element comprising an upstream end wall defining a first opening for allowing fluid communication between an interior of the first tubular element and an exterior of the first tubular element; and a second tubular element comprising a second tubular element end wall defining a second opening for allowing fluid communication between an interior of the second tubular element and an exterior of the second tubular element; wherein the first tubular element is positioned within the rod upstream of, and adjacent to, the second tubular element.

Ex2. An aerosol-generating article according to Ex1 , wherein the downstream end of the first tubular element is in physical contact with the upstream end of the second tubular element.

Ex3. An aerosol-generating article according to Ex1 or Ex2, wherein the first tubular element and the second tubular element are positioned upstream of the aerosol-forming substrate.

Ex4. An aerosol-generating article according to any one of Ex1 to Ex3, wherein the first tubular element is the most upstream element of the aerosol-generating article. Ex5. An aerosol-generating article according to any one of Ex1 to Ex4, wherein the first tubular element is positioned at the extreme upstream end of the aerosol-generating article. Ex6. An aerosol-generating article according to any one of Ex1 to Ex5, wherein the second tubular element is positioned adjacent to the upstream end aerosol-forming substrate.

Ex7. An aerosol-generating article according to any one of Ex1 to Ex6, wherein the second tubular element is in physical contact with an upstream end of the aerosol-forming substrate. Ex8. An aerosol-generating article according to Ex7, wherein the second tubular element end wall is in physical contact with an upstream end of the aerosol-forming substrate.

Ex9. An aerosol-generating article according to Ex1 or Ex2, wherein the first tubular element and the second tubular element are positioned downstream of the aerosol-forming substrate.

Ex10. An aerosol-generating article according to Ex9, wherein second tubular element is the most downstream element of the aerosol-generating article.

Ex11. An aerosol-generating article according to Ex9 or Ex10, wherein second tubular element is positioned at the extreme downstream end of the aerosol-generating article.

Ex12. An aerosol-generating article according to any one of Ex9 to Ex11 , wherein the first tubular element is positioned adjacent to the downstream end of the aerosol-forming substrate.

Ex13. An aerosol-generating article according to any one of Ex9 to Ex12, wherein the first tubular element is in physical contact with the downstream end of the aerosol-forming substrate.

Ex14. An aerosol-generating article according to Ex13, wherein the upstream end wall of the first tubular element is in physical contact with the downstream end of the aerosol-forming substrate.

Ex15. An aerosol-generating article according to any one of Ex9 to Ex14, wherein any element positioned downstream of the second tubular element has a resistance to draw of about 0 mmH₂0.

Ex16. An aerosol-generating article according to any one of Ex9 to Ex15, wherein there is no filter element made from cellulose acetate positioned downstream of the second tubular element.

Ex17. An aerosol-generating article according to any one of Ex9 to Ex16, wherein there is no filter element positioned downstream of the second tubular element.

Ex18. An aerosol-generating article according to any one of Ex9 to Ex17, wherein the second tubular element end wall of the second tubular element is positioned less than 15 millimetres from the downstream end of the aerosol-generating article. Ex19. An aerosol-generating article according to any one of Ex9 to Ex18, wherein the second tubular element end wall of the second tubular element is positioned less than 10 millimetres from the downstream end of the aerosol-generating article.

Ex20. An aerosol-generating article according to any one of Ex9 to Ex19, wherein the second tubular element end wall of the second tubular element is positioned less than 5 millimetres from the downstream end of the aerosol-generating article.

Ex21. An aerosol-generating article according to any one of Ex1 to Ex20, wherein the upstream end wall is formed by a first folded end portion, preferably wherein the first folded end portion is a flanged end portion.

Ex22. An aerosol-generating article according to any one of Ex1 to Ex121 , wherein the second tubular element end wall is formed by a second folded end portion, preferably wherein the second folded end portion is a flanged end portion.

Ex23. An aerosol-generating article according to any one of Ex1 to Ex22, wherein there is no end wall at the downstream end of the first tubular element.

Ex24. An aerosol-generating article according to any one of Ex1 to Ex23, wherein there is no end wall at the upstream end of the second tubular element.

Ex25. An aerosol-generating article according to any one of Ex1 to Ex24, wherein the first tubular element comprises a first cavity extending from the upstream end wall of the first tubular element to a downstream end of the first tubular element.

Ex26. An aerosol-generating article according to Ex25, wherein the first cavity is empty.

Ex27. An aerosol-generating article according to Ex25 or Ex26, wherein the first cavity has a diameter that is at least about 50 percent a diameter of the first tubular element.

Ex28. An aerosol-generating article according to any one of Ex25 to Ex27, wherein the first cavity has a diameter that is at least about 60 percent the diameter of the first tubular element. Ex29. An aerosol-generating article according to any one of Ex25 to Ex28, wherein the first cavity has a diameter that is at least about 70 percent of the diameter of the first tubular element.

Ex30. An aerosol-generating article according to any one of Ex25 to Ex29, wherein the first cavity has a diameter that is at least about 80 percent of the diameter of the first tubular element.

Ex31 . An aerosol-generating article according to any one of Ex25 to Ex30, wherein the first cavity has a diameter that is at least about 90 percent of the diameter of the first tubular element.

Ex32. An aerosol-generating article according to any one of Ex25 to Ex31 , wherein the first cavity has a diameter that is at least about 95 percent of the diameter of the first tubular element. Ex33. An aerosol-generating article according to any one of Ex25 to Ex32, wherein the diameter of the first cavity increases between the upstream end wall of the first tubular element and the downstream end of the first tubular element.

Ex34. An aerosol-generating article according to any one of Ex25 to Ex32, wherein the diameter of the first cavity increases from the upstream end wall of the first tubular element to the downstream end of the first tubular element.

Ex35. An aerosol-generating article according to any one of Ex25 to Ex32, wherein the diameter of the first cavity decreases between the upstream end wall of the first tubular element and the downstream end of the first tubular element.

Ex36. An aerosol-generating article according to any one of Ex25 to Ex32, wherein the diameter of the first cavity decreases from the upstream end wall of the first tubular element to the downstream end of the first tubular element.

Ex37. An aerosol-generating article according to any one of Ex25 to Ex32, wherein the diameter of the first cavity is substantially constant between the upstream end wall of the first tubular element and the downstream end of the first tubular element.

Ex38. An aerosol-generating article according to Ex37, wherein the diameter of the cavity is substantially constant from the upstream end wall of the first tubular element to the downstream end of the first tubular element.

Ex39. An aerosol-generating article according to any one of Ex1 to Ex38, wherein the second tubular element comprises a second cavity extending from the upstream end of the second tubular element to the downstream end of the second tubular element.

Ex40. An aerosol-generating article according to any one of Ex39, wherein the second cavity is empty.

Ex41 . An aerosol-generating article according to Ex39 or Ex40, wherein a diameter of the second cavity is at least about 50 percent a diameter of the second tubular element.

Ex42. An aerosol-generating article according to any one of Ex39 to Ex41 , wherein the diameter of the second cavity is at least about 60 percent the diameter of the second tubular element.

Ex43. An aerosol-generating article according to any one of Ex39 to Ex42, wherein the diameter of the second cavity is at least about 70 percent of the diameter of the second tubular element.

Ex44. An aerosol-generating article according to any one of Ex39 to Ex43, wherein the diameter of the second cavity is at least about 80 percent of the diameter of the second tubular element.

Ex45. An aerosol-generating article according to any one of Ex39 to Ex44, wherein the diameter of the second cavity is at least about 90 percent of the diameter of the second tubular element. Ex46. An aerosol-generating article according to any one of Ex39 to Ex45, wherein the diameter of the second cavity is at least about 95 percent of the diameter of the second tubular element.

Ex47. An aerosol-generating article according to any one of Ex39 to Ex46, wherein the diameter of the second cavity increases between the upstream end of the second tubular element and the downstream end of the second tubular element.

Ex48. An aerosol-generating article according to any one of Ex39 to Ex46, wherein the diameter of the second cavity increases from the upstream end of the second tubular element to the downstream end of the second tubular element.

Ex49. An aerosol-generating article according to any one of Ex39 to Ex46, wherein the diameter of the second cavity decreases between the upstream end of the second tubular element and the downstream end of the second tubular element.

Ex50. An aerosol-generating article according to any one of Ex39 to Ex46, wherein the diameter of the second cavity decreases from the upstream end of the second tubular element to the downstream end of the second tubular element.

Ex51. An aerosol-generating article according to any one of Ex39 to Ex46, wherein the diameter of the second cavity is substantially constant between the upstream end of the second tubular element and the downstream end of the second tubular element.

Ex52. An aerosol-generating article according to Ex51 , wherein the diameter of the second cavity is substantially constant from the upstream end of the second tubular element to the downstream end of the second tubular element.

Ex53. An aerosol-generating article according to any one of Ex1 to Ex52, comprising a continuous cavity extending from the upstream end wall of the first tubular element to the downstream end of the second tubular element.

Ex54. An aerosol-generating article according to Ex53, wherein the continuous cavity has a uniform diameter along the entire length of the continuous cavity.

Ex55. An aerosol-generating article according to any one of Ex1 to Ex54, wherein the first tubular element has a length greater than a length of the second tubular element.

Ex56. An aerosol-generating article according to any one of Ex1 to Ex54, wherein the first tubular element has a length less than the length of the second tubular element.

Ex57. An aerosol-generating article according to any one of Ex1 to Ex54, wherein the first tubular element has a length substantially equal to a length of the second tubular element.

Ex58. An aerosol-generating article according to any one of Ex1 to Ex57, wherein the first opening is radially aligned with the second opening.

Ex59. An aerosol-generating article according to any one of Ex1 to Ex57, wherein the first opening is radially offset from the second opening. Ex60. An aerosol-generating article according to any one of Ex1 to Ex59, wherein the first opening is radially central.

Ex61. An aerosol-generating article according to any one of Ex1 to Ex59, wherein the second opening is radially central.

Ex62. An aerosol-generating article according to any one of Ex1 to Ex60, wherein the first opening has an equivalent diameter equal to, or greater than, about 10 percent of the diameter of the upstream end wall.

Ex63. An aerosol-generating article according to any one of Ex1 to Ex61, wherein the first opening has an equivalent diameter equal to, or greater than, about 20 percent of the diameter of the upstream end wall.

Ex64. An aerosol-generating article according to any one of Ex1 to Ex62, wherein the first opening has an equivalent diameter equal to, or greater than, about 30 percent of the diameter of the upstream end wall.

Ex65. An aerosol-generating article according to any one of Ex1 to Ex63, wherein the first opening has an equivalent diameter equal to, or greater than, about 40 percent of the diameter of the upstream end wall.

Ex66. An aerosol-generating article according to any one of Ex1 to Ex64, wherein the first opening has an equivalent diameter equal to, or greater than, about 50 percent of the diameter of the upstream end wall.

Ex67. An aerosol-generating article according to any one of Ex1 to Ex65, wherein the first opening has an equivalent diameter of between about 1 millimetre and about 3 millimetres.

Ex68. An aerosol-generating article according to any one of Ex1 to Ex66, wherein the second opening has an equivalent diameter equal to, or greater than, about 10 percent of the diameter of the second tubular element end wall.

Ex69. An aerosol-generating article according to any one of Ex1 to Ex67, wherein the second opening has an equivalent diameter equal to, or greater than, about 20 percent of the diameter of the second tubular element end wall.

Ex70. An aerosol-generating article according to any one of Ex1 to Ex68, wherein the second opening has an equivalent diameter equal to, or greater than, about 30 percent of the diameter of the second tubular element end wall.

Ex71. An aerosol-generating article according to any one of Ex1 to Ex69, wherein the second opening has an equivalent diameter equal to, or greater than, about 40 percent of the diameter of the second tubular element end wall.

Ex72. An aerosol-generating article according to any one of Ex1 to Ex70, wherein the second opening has an equivalent diameter equal to, or greater than, about 50 percent of the diameter of the second tubular element end wall. Ex73. An aerosol-generating article according to any one of Ex1 to Ex71 , wherein the second opening has an equivalent diameter of between about 1 millimetre and about 3 millimetres.

Ex74. An aerosol-generating article according to any one of Ex1 to Ex72, wherein the first opening has an equivalent diameter less than an equivalent diameter of the second opening. Ex75. An aerosol-generating article according to any one of Ex1 to Ex72, wherein the first opening has an equivalent diameter less than an equivalent diameter of the second opening. Ex76. An aerosol-generating article according to any one of Ex1 to Ex72, wherein the first opening has an equivalent diameter substantially equal to an equivalent diameter of the second opening.

Ex77. An aerosol-generating article according to any one of Ex1 to Ex76, wherein the upstream end wall defines a plurality of openings for allowing fluid communication between the interior of the first tubular element and the exterior of the first tubular element.

Ex78. An aerosol-generating article according to any one of Ex1 to Ex77, wherein the second tubular element end wall defines a plurality of openings for allowing fluid communication between the interior of the second tubular element and the exterior of the second tubular element.

Ex79. An aerosol-generating article according to any one of Ex1 to Ex78, wherein the number of openings defined in the upstream end wall is greater than the number of openings defined in the second tubular element end wall.

Ex80. An aerosol-generating article according to any one of Ex1 to Ex79, further comprising a front plug located upstream of the aerosol-forming substrate.

Ex81 . An aerosol-generating article according to Ex80, wherein the front plug is the most upstream element of the aerosol-generating article.

Ex82. An aerosol-generating article according to Ex80 or Ex81 , wherein the front plug is in physical contact with the upstream end of the aerosol-forming substrate.

Ex83. An aerosol-generating article according to any one of Ex80 to Ex82, wherein the front plug is a hollow element, for example the front plug is in the form of a tube.

Ex84. An aerosol-generating article according to any one of Ex80 to Ex83, wherein the front plug is made from cellulose acetate, for example the front plug is a hollow cellulose acetate tube.

Ex85. An aerosol-generating article according to any one of Ex80 to Ex84, wherein the front plug has a length of between about 2 millimetres and about 8 millimetres.

Ex86. An aerosol-generating according to claim to any one of Ex80 to Ex85, wherein the front plug has a length of about 5 millimetres.

Ex87. An aerosol-generating article according to any one of Ex1 to Ex86, wherein the upstream end wall of the first tubular element comprises a hydrophobic coating. Ex88. An aerosol-generating article according to any one of Ex1 to Ex87, wherein the second tubular element end wall of the second tubular element comprises a hydrophobic coating.

Ex89. An aerosol-generating article according to any one of Ex1 to Ex88, wherein the first tubular element comprises a hydrophobic coating.

Ex90. An aerosol-generating article according to any one of Ex1 to Ex89, wherein the second tubular element comprises a hydrophobic coating.

Ex91. An aerosol-generating article according to any one of Ex1 to Ex90, wherein one or both of the first tubular element and the second tubular element are formed from a paper material.

Ex92. An aerosol-generating article according to any one of Ex1 to Ex91 , wherein one or both of the first tubular element and the second tubular element are formed from cardboard. Ex93. An aerosol-generating article according to any one of Ex1 to Ex92, wherein a tubular wall thickness of the first tubular element is greater than a tubular wall thickness of the second tubular element.

Ex94. An aerosol-generating article according to any one of Ex1 to Ex92, wherein a tubular wall thickness of the first tubular element is less than a tubular wall thickness of the second tubular element.

Ex95. An aerosol-generating according to ay one of Ex1 to Ex94, wherein the tubular wall thickness is between about 150 micrometres and about 600 micrometres.

Ex96. An aerosol-generating article according to any one of Ex1 to Ex95 comprising an outer wrapper circumscribing at least the first tubular element and the second tubular element.

Ex97. An aerosol-generating article according to Ex96, wherein the outer wrapper extends from the upstream end of the first tubular element to the downstream end of the second tubular element.

Ex98. An aerosol-generating article according to Ex96 or Ex97, wherein the outer wrapper circumscribes all of the plurality of elements of the aerosol-generating article which are assembled in the form of a rod.

Ex99. An aerosol-generating article according to any one of Ex96 to Ex98, wherein the outer wrapper is a paper wrapper or a non-paper wrapper.

Ex100. An aerosol-generating article according to any one of Ex1 to Ex99, further comprising a ventilation zone positioned between an upstream end of the aerosol-generating article and a downstream end of the aerosol-generating article.

Ex101. An aerosol-generating article according to Ex100, wherein the ventilation zone is positioned downstream of the aerosol-forming substrate. Ex102. An aerosol-generating article according to Ex100 or Ex101 , wherein the ventilation zone is positioned at a location along the first tubular element.

Ex103. An aerosol-generating article according to Ex100 or Ex101 , wherein the ventilation zone is positioned at a location along the second tubular element.

Ex104. An aerosol-generating article according to any one of Ex100 to Ex103, wherein the ventilation zone has a ventilation level of between about 30 percent and about 60 percent.

Ex105. An aerosol-generating article according to any one of Ex1 to Ex104 further comprising a susceptor element positioned in thermal contact with the aerosol-forming substrate.

Ex106. An aerosol-generating article according to Ex105, wherein the susceptor element is positioned within the aerosol-forming substrate.

Ex107. An aerosol-generating article according to E105 or Ex106, wherein the susceptor element is an elongate susceptor element arranged longitudinally within the aerosol-forming substrate.

Ex108. An aerosol-generating article according to any one of Ex105 to Ex107, wherein the susceptor element extends along a radially central axis of the aerosol-forming substrate.

Ex109. An aerosol-generating article according to any one of Ex105 to Ex108, wherein the susceptor element extends from an upstream end of the aerosol-forming substrate to a downstream end of the aerosol-forming substrate.

Ex110. An aerosol-generating article according to any one of Ex105 to Ex109, wherein the susceptor element is in the form of a pin, a rod or a blade.

Ex111. An aerosol-generating article according to any one of Ex1 to Ex110, wherein the aerosol-forming substrate comprises tobacco cut filler.

Ex112. An aerosol-generating article according to any one of Ex1 to Ex111 wherein the aerosol-forming substrate comprises tobacco cast leaf.

Ex113. An aerosol-generating article according to any one of Ex1 to Ex112, wherein the aerosol-forming substrate is a gathered sheet of homogenised tobacco material.

Ex114. An aerosol-generating article according to Ex113, wherein the gathered sheet of homogenised tobacco material extends across substantially the entire transverse cross- sectional area of the rod.

Ex115. An aerosol-generating article according to Ex113 or Ex114, wherein the gathered sheet of homogenised tobacco material has a grammage 100 g/m2 and about 300 g/m2.

Ex116. An aerosol-generating article according to any one of Ex113 to Ex115, wherein the gathered sheet of homogenised tobacco material has a thickness of between 50 pm and about 300 pm. Ex117. An aerosol-generating article according to any one of Ex113 to Ex116, wherein the gathered sheet of homogenised tobacco material is a crimped and gathered sheet of homogenised tobacco material.

Ex118. An aerosol-generating article according to Ex117, wherein the crimped and gathered sheet of homogenised tobacco material has a plurality of ridges or corrugations substantially parallel to the longitudinal axis of the rod.

Ex119. An aerosol-generating article according to any one of Ex1 to Ex118, wherein the aerosol-forming substrate comprises one or more aerosol-formers.

Ex120. An aerosol-generating article according to Ex119, wherein the aerosol-forming substrate has an aerosol former content of between about 10 percent and about 50 percent by weight on a dry weight basis.

Ex121. An aerosol-generating article according to any one of Ex1 to Ex120, wherein the aerosol-forming substrate has a length of between about 10 millimetres and about 15 millimetres.

Ex122. An aerosol-generating article according to any one of Ex1 to Ex121 , wherein the aerosol-forming substrate has a length of between about 11 millimetres and about 12 millimetres.

Examples will now be further described with reference to the figures in which:

Figure 1 depicts a schematic cross-sectional view of an aerosol-generating article according to a first example of the present disclosure;

Figure 2 depicts a schematic cross-sectional view of an aerosol-generating article according to a second example of the present disclosure;

Figure 3 depicts a schematic cross-sectional view of an aerosol-generating article according to a third example of the present disclosure;

Figure 4 depicts a schematic cross-sectional view of an aerosol-generating article according to a fourth example of the present disclosure;

Figure 5 depicts a schematic cross-sectional view of an aerosol-generating article according to a fifth example of the present disclosure;

Figure 6 depicts a schematic cross-sectional view of an aerosol-generating article according to a sixth example of the present disclosure;

Figure 7 depicts a schematic cross-sectional view of an aerosol-generating article according to a seventh example of the present disclosure;

Figure 8 depicts a schematic cross-sectional view of an aerosol-generating article according to an eighth example of the present disclosure;

Figure 9 depicts a schematic cross-sectional view of an aerosol-generating article according to a nineth example of the present disclosure; Figure 10 depicts a perspective view of a tubular element according to the present disclosure;

Figures 11A to 11 D depict a method of forming a tubular element according to the present disclosure; and

Figure 12 depicts an alternative method of forming a tubular element according to the present disclosure.

Figure 1 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a first example. The plurality of elements include an aerosol-forming substrate 10, a first tubular element 20 and a second tubular element 30. The aerosol-generating article 1 has an overall length of about 45 millimetres and extends from a distal end 2 (or upstream end) to a mouth end 3 (or downstream end). The aerosolgenerating article 1 has a diameter of about 7 millimetres.

The aerosol-generating article 1 comprises an outer wrapper 40 that circumscribes all of the plurality of elements which are assembled in the form of a rod. The outer wrapper 40 is made from tipping paper and extends from the upstream end 2 of the aerosolgenerating article 1 to the downstream end 3 of the aerosol-generating article 1 . The outer wrapper 40 has a thickness of about 500 micrometres.

The aerosol-forming substrate 10 comprises a crimped and gathered sheet of homogenised tobacco material having a plurality of ridges or corrugations extending substantially parallel to the longitudinal axis of the rod. The crimped and gathered sheet of homogenised tobacco material extends across substantially the entire transverse cross- sectional area of the aerosol-generating article 1. The aerosol-forming substrate 10 comprises an aerosol former, namely glycerol, and has an aerosol former content of about 10 percent on a dry weight basis. The aerosol-forming substrate 10 has a length of about 12 millimetres. The aerosol-forming substrate 10 is substantially cylindrical and has a diameter of about 6 millimetres.

The first tubular element 20 is positioned within the rod upstream of, and adjacent to, the second tubular element 30. In this embodiment, the downstream end of the first tubular element 20 is spaced, in the longitudinal direction, from the upstream end of the second tubular element 30. As such, there is a gap 50 of empty space between the downstream end of the first tubular element 20 and the upstream end of the second tubular element 30. The gap has a length of about 4 millimetres.

The first tubular element 20 comprises an upstream end wall 21 defining a first opening 22 for allowing fluid communication between an interior of the first tubular element 20 and an exterior of the first tubular element 20. The upstream end wall 21 is formed by a first folded end portion, as explained in more detail in relation to Figures 11A to 11 D. The first opening 22 is in a radially central position of the upstream end wall 21 and has an equivalent diameter of about 3 millimetres.

The upstream end wall 21 of the first tubular element 20 is positioned adjacent to, and in physical contact with, the downstream end of the aerosol-forming substrate 10. The first tubular element 20 has a length of about 12 millimetres and extends from the downstream end of the aerosol-forming substrate 20 towards the second tubular element 30. The first tubular element 20 is cylindrical and has a diameter of about 6 millimetres. The first tubular element 20 is made from cardboard having a basis weight of about 100 grams per square metre, and a thickness of about 1 millimetre. The first tubular element 20 has an RTD of about 40 millimetres H2O.

The second tubular element 30 comprises a second tubular element end wall 31 defining a second opening 32 for allowing fluid communication between an interior of the second tubular element 30 and an exterior of the second tubular element 30. As seen, the second tubular element end wall 31 is positioned at the downstream end of the second tubular element 30. Thus, it will be referred to as a downstream end wall. The downstream end wall 31 is formed by a second folded end portion. The second opening 32 is in a radially central position of the downstream end wall 31 and has an equivalent diameter of about 3 millimetres.

The second tubular element 30 is the most downstream element of the aerosolgenerating article 1 , however, the second tubular element 30 does not extend to the downstream end 3 of the aerosol-generating article 1. Instead, the downstream end wall 31 of the second tubular element 30 is spaced from the downstream end 3 of the aerosolgenerating article 1 by about 5 millimetres. The second tubular element 30 is cylindrical and has a diameter of about 6 millimetres and a length of about 12 millimetres. The second tubular element 30 is made from cardboard having a basis weight of about 100 grams per square metre, and a thickness of about 1 millimetre. The second tubular element 30 has an RTD of about 40 millimetres H2O.

In use, a heating element from an electrically operated aerosol-generating device is inserted into, or positioned around, the aerosol-forming substrate 10 which causes the aerosol-forming substrate 10 to heat up and release volatile compounds. A consumer draws on the downstream end 3 of the aerosol-generating article 1 causing air to be drawn through the upstream end 2 of the aerosol-generating article 1 . The air is then drawn through the aerosol-forming substrate 10 where volatile compounds released from the heated aerosolforming substrate 10 are entrained in the air drawn through the aerosol-generating article 1. The volatile compounds and air then pass through the first opening 22 of the first tubular element 30. The volatile compounds and air cool and condense within the first tubular element 20 and second tubular element 30 by, in part, releasing heat to the tubular walls of the first tubular element 20 and the second tubular element 30. The cooled and condense volatile compounds and air form an aerosol which is drawn through the second opening 32 of the second tubular element 30 and inhaled by the consumer.

Figure 2 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a second example. The aerosol-generating article 1 of Figure 2 is similar to the aerosol-generating article 1 of Figure 1 and also comprises an aerosol-forming substrate 10, a first tubular element 20 and a second tubular element 30. However, the first tubular element 20 is positioned adjacent to the aerosolforming substrate 10 but is not in physical contact with the downstream end of the aerosolforming substrate 10. Instead, there is a gap 60 positioned between the downstream end of the aerosol-forming substrate 10 and the upstream end wall 21 of the first tubular element 20. The gap 60 has a length of about 5 millimetres. Furthermore, the second tubular element 30 is positioned at an extreme downstream end of the aerosol-generating article 1 . That is, the downstream end wall 31 of the second tubular element 30 is positioned at the downstream end 3 of the aerosol-generating article 1.

Figure 3 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a third example. The aerosol-generating article 1 of Figure 3 is similar to the aerosol-generating article 1 of Figure 1 and also comprises an aerosol-forming substrate 10, a first tubular element 20 and a second tubular element 30. However, the downstream end of the first tubular element 20 is in physical contact with the upstream end of the second tubular element 30, and there is no gap between the first tubular element and the second tubular element. Furthermore, the second tubular element 30 is positioned at an extreme downstream end of the aerosol-generating article 1.

Figure 4 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a fourth example. The first tubular element 20 has a length that is less than the length of the second tubular element 30. In this embodiment, the first tubular element 20 has a length of about 13 millimetres and the second tubular element 30 has a length of about 20 millimetres. Furthermore, the first tubular element 20 has a tubular wall thickness that is less than a tubular wall thickness of the second tubular element 30. In this embodiment, the first tubular element 20 has a tubular wall thickness of about 0.3 millimetres and the second tubular element 30 has a tubular wall thickness of about 0.6 millimetres. Moreover, the first opening 22 has an equivalent diameter greater than the equivalent diameter of the second opening 32. In this embodiment, the first opening 22 has an equivalent diameter of about 3.5 millimetres and the second opening 32 has an equivalent diameter of about 2.5 millimetres.

Figure 5 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a fifth example. The aerosol-generating article 1 of Figure 5 is similar to the aerosol-generating article 1 of Figure 3. However, the aerosolgenerating article 1 of Figure 5 further comprises an elongate susceptor element 70.

The elongate susceptor element 70 is positioned within the aerosol-forming substrate 10. In more detail, the susceptor element 70 is arranged substantially longitudinally within the aerosol-forming substrate 10, such as to be approximately parallel to the longitudinal axis of the rod. Moreover, the susceptor element 70 is positioned in a radially central position within the rod and extends effectively along the longitudinal axis of the rod. The susceptor element 70 extends all the way from an upstream end to a downstream end of the aerosolforming substrate 10. In effect, the susceptor element 70 has substantially the same length as the aerosol-forming substrate 10.

The susceptor element 70 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 end wall 21 of the first tubular element 20 is positioned adjacent to, and in physical contact with, the downstream end of the aerosol-forming substrate 10. Furthermore, the width of the susceptor element 70 is greater than the diameter of the first opening 22 of the first tubular element 20.

Figure 6 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a sixth example. The aerosol-generating article 1 of Figure 6 is similar to the aerosol-generating article 1 of Figure 5 but further comprises a front plug 80 and a ventilation zone 90.

The front plug 70 is located immediately upstream of the aerosol-forming substrate 10. The downstream end of the front plug abuts the upstream end of the aerosol-forming substrate 10. This advantageously prevents the susceptor element 70 from being dislodged. Further, this ensures that the consumer cannot accidentally contact the heated susceptor element 70 after use.

The front plug 80 is provided in the form of a cylindrical plug of cellulose acetate circumscribed by a stiff wrapper. The front plug 80 has a length of about 5 millimetres and an RTD of about 30 millimetres H2O.

The aerosol-generating article 1 comprises a ventilation zone 90 provided at a location between the first tubular element 20 and the second tubular element 30. In more detail, the ventilation zone 90 comprises a plurality of perforations through the outer wrapper 40. The ventilation level of the aerosol-generating article 1 is about 40 percent.

Figure 7 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a seventh example. The aerosol-generating article 1 of Figure 7 is similar to the aerosol-generating article 1 of Figure 5 but further comprises a ventilation zone 90. In more detail, the ventilation zone 90 is provided at about 4 millimetres from the downstream end of the second tubular element 30 and comprises a plurality of perforations through the outer wrapper 40 and the second tubular element 30. The ventilation level of the aerosol-generating article 1 is about 40 percent.

Figure 8 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to an eighth example. The aerosol-generating article 1 of Figure 8 is similar to the aerosol-generating article 1 of Figure 5. However, in the aerosol-generating article 1 of Figure 8, the second element tubular end wall 31 is positioned at an upstream end of the second tubular element 30.

Figure 9 depicts an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod, according to a nineth example. The plurality of elements include a first tubular element 20, a second tubular element 30, a capsule 110 comprising an aerosol-forming substrate, and a third tubular element 100.

The downstream end of the first tubular element 20 is in physical contact with the upstream end of the second tubular element 30, and there is no gap between the first tubular element 20 and the second tubular element 30. Also, the second tubular element 30 is positioned at an extreme downstream end 3 of the aerosol-generating article 1.

In this example, there is a third tubular element 100 which is constructed in the same way as the first tubular element 20 and second tubular element 30. The third tubular element

100 comprises an upstream end wall 101 defining an third opening 102 for allowing fluid communication between an interior of the third tubular element 100 and an exterior of the third tubular element 100. The third tubular element 100 extends from the upstream end 2 of the aerosol-generating article 1 to the upstream end wall 21 of the first tubular element 20. The third tubular element 100 comprises a cavity 104 extending from the upstream end wall

101 to the downstream end of the third tubular element 100.

In contrast to the first to eighth examples, in the nineth example, the aerosolgenerating article 1 comprises a capsule 110 comprising an aerosol-forming substrate in the form of an inhalable dry powder. During use, a consumer inserts a rupturing element, such as a needle, through the third opening 102 to rupture the capsule 110. The upstream end wall 21 of the first tubular element 20 restricts the downstream movement of the capsule 110 thereby assisting in the process of rupturing the capsule. Once the capsule is ruptured, the aerosol-forming substrate within the capsule is released when a consumer draws on the downstream end 3 of the aerosol-generating article 1 .

Figure 10 depicts a perspective view of the first tubular element 20 according to Figure 1. The upstream end wall 21 extends substantially transverse to the longitudinal direction of the aerosol generating article 1 and the longitudinal direction of the first tubular element 20.

Figures 11 A to 11 D shows a first tubular element 20, for an aerosol-generating article in accordance with the present disclosure, through different stages of its formation. These Figures therefore illustrate a method of forming the first tubular element, such as the first tubular element 20 of Figure 1. A similar method is used to form a second tubular element of the present disclosure.

As illustrated by Figure 11A, the method commences by providing a tubular element precursor 200 comprising a tubular body 201 defining a cavity 203 extending along a longitudinal axis from a first end of the tubular body to a second end of the tubular body and a first end portion 202 adjacent to and integrally formed with the first end of the tubular body 201.

To form the upstream end wall 21 , a folding force is applied to the tubular element precursor 200 to bend the first end portion 202 about a fold point 204. The folding force deflects the first end portion 202 inwards relative to the tubular body 201 (as indicated by the dashed curved arrows in Figures 11 B and 11C) and towards the cavity 203. The folding force continues to be applied until the first end portion 202 has been folded by an angle of greater than 90 degrees, as measured relative to the walls of the tubular body. The folding force is then released. The inherent resilient properties of the paper material (such as paper, paperboard or cardboard) of the tubular element precursor 200 will cause the first end portion 202 to partially revert back along its folding path, such that the first end portion 202 reaches a position in which it extends substantially transverse to the longitudinal direction of the tubular body 201 . This position is illustrated by Figure 11 D.

Figure 12 shows an alternative method for forming a tubular element according to the present disclosure. In the first step 301 , a cellulose material, such as paper, is mixed with water to form a pulp. Typically, the water has a temperature of around 40 Celsius to 70 Celsius. In the second step 302, the pulp is inserted into a mould to produce the desired shape of the tubular element. In the third step 303, the moulded pulp is ejected from the mould and dried to remove the moisture from the moulded pulp, thereby forming the tubular element.

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 ± 5% 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 comprising a plurality of elements assembled in the form of a rod, the plurality of elements comprising: an aerosol-forming substrate; a first tubular element comprising an upstream end wall defining a first opening for allowing fluid communication between an interior of the first tubular element and an exterior of the first tubular element; and a second tubular element comprising a second tubular element end wall defining a second opening for allowing fluid communication between an interior of the second tubular element and an exterior of the second tubular element; wherein the first tubular element is positioned within the rod upstream of, and adjacent to, the second tubular element.

2. An aerosol-generating article according to claim 1 , wherein the downstream end of the first tubular element is in physical contact with the upstream end of the second tubular element.

3. An aerosol-generating article according to claim 1 or 2, wherein the second tubular element end wall is positioned at the downstream end of the second tubular element.

4. An aerosol-generating article according to any preceding claim, wherein the first tubular element and the second tubular element are positioned downstream of the aerosolforming substrate.

5. An aerosol-generating article according to claim 4, wherein any element positioned downstream of the second tubular element has a resistance to draw that is less than the resistance to draw of one or more of the first tubular element, the second tubular element, or the combination of the first tubular element and the second tubular element.

6. An aerosol-generating article according to claim 4 or 5, wherein any element positioned downstream of the second tubular element has a resistance to draw of less than about 10 mmH₂0, preferably a resistance to draw of about 0 mmH₂0.

7. An aerosol-generating article according to any one of claims 1 to 4, wherein the second tubular element is the most downstream element of the aerosol-generating article.

8. An aerosol-generating article according to any preceding claim, wherein the upstream end wall of the first tubular element is in physical contact with the downstream end of the aerosol-forming substrate.

9. An aerosol-generating article according to any preceding claim, wherein the upstream end wall is formed by a first folded end portion, preferably wherein the second tubular element end wall is formed by a second folded end portion.

10. An aerosol-generating article according to any preceding claim, wherein the first tubular element is formed from first material and the second tubular element is formed from a second material, wherein the basis weight of the first material is greater than the basis weight of the second material.

11. An aerosol-generating article according to any preceding claim, wherein a tubular wall thickness of the first tubular element is greater than a tubular wall thickness of the second tubular element.

12. An aerosol-generating article according to any preceding claim, wherein one or more of the first tubular element and the second tubular element comprises a hydrophobic coating.

13. An aerosol-generating article according to any preceding claim, further comprising a front plug located upstream of the aerosol-forming substrate.

14. An aerosol-generating article according to any preceding claim, further comprising a ventilation zone positioned between an upstream end of the aerosol-generating article and a downstream end of the aerosol-generating article.

15. An aerosol-generating article according to any preceding claim, further comprising a susceptor element positioned in thermal contact with the aerosol-forming substrate.