WO2024003312A1

WO2024003312A1 - Aerosol-generating article having two or more substrate segments

Info

Publication number: WO2024003312A1
Application number: PCT/EP2023/067927
Authority: WO
Inventors: Jerome Uthurry
Original assignee: Philip Morris Products S.A.
Priority date: 2022-06-30
Filing date: 2023-06-29
Publication date: 2024-01-04

Abstract

An aerosol-generating article (10)(110)(210) comprises: an aerosol-generating rod (12)(112)(212) for producing an inhalable aerosol upon heating, the aerosol-generating rod (12)(112)(212) comprising: a first aerosol-generating segment (24)(124)(224) comprising a first aerosol-generating substrate and a second aerosol-generating segment (26)(126)(226) at a location upstream of the first aerosol-generating segment (24)(124)(224) and comprising a second aerosol-generating substrate. The second aerosol-generating substrate has a higher aerosol former content than the first aerosol-generating substrate. The second aerosol- generating substrate has a higher density than the first aerosol-generating substrate.

Description

AEROSOL-GENERATING ARTICLE HAVING TWO OR MORE SUBSTRATE SEGMENTS

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

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

A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosolgenerating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosolgenerating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosol-generating substrate. Use of an aerosol-generating article in combination with an external heating system is also known. For example, WO 2020/115151 describes the provision of one or more heating elements arranged around the periphery of the aerosol-generating article when the aerosol-generating article is received in a cavity of the aerosol-generating device. As an alternative, inductively heatable aerosolgenerating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosol-generating substrate have been proposed by WO 2015/176898.

Aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted present a number of challenges that were not encountered with conventional smoking articles.

Firstly, tobacco-containing substrates are typically heated to significantly lower temperatures compared with the temperatures reached by the combustion front in a conventional cigarette. This may have an impact on nicotine release from the tobaccocontaining substrate and nicotine delivery to the consumer. At the same time, if the heating temperature is increased in an attempt to boost nicotine delivery, then the aerosol generated typically needs to be cooled to a greater extent and more rapidly before it reaches the consumer. Secondly, heating an aerosol-generating substrate to the temperature required for aerosol formation takes a certain amount of time, and so there may be a delay in aerosol delivery to the consumer after heating has been initiated. This phenomenon, whereby when the user initially draws upon the article, the aerosol reaching the user may be relatively low in flavour or nicotine content or both, is often referred to as “cold puff” effect or “empty puff” effect.

It would be desirable to provide a novel aerosol-generating article having an arrangement that provides improved consistency in the aerosol delivery during heating. It would be further desirable to provide such an aerosol-generating article which provides greater control over the puff profile and in particular, which is capable of providing a satisfactory aerosol delivery to the consumer within a relatively short time after the initiation of heating. It would be further desirable if such an aerosol-generating article could be produced using existing manufacturing apparatus and methods, without significant modification.

The present disclosure relates to an aerosol-generating article. The aerosolgenerating article may comprise an aerosol-generating rod for producing an inhalable aerosol upon heating. The aerosol-generating rod may comprise a first aerosol-generating segment comprising a first aerosol-generating substrate. The aerosol-generating rod may comprise a second aerosol-generating segment comprising a second aerosol-generating substrate. The second aerosol-generating substrate may be located upstream of the first aerosol-generating substrate. The second aerosol-generating substrate may have a higher aerosol former content than the first aerosol-generating substrate. The second aerosol-generating substrate may have a higher density than the first aerosol-generating substrate. The first aerosolgenerating substrate may comprise at least one aerosol former, wherein the aerosol former content of the first aerosol-generating substrate is less than 30 percent by weight on a dry weight basis. The second aerosol-generating substrate may comprise at least one aerosol former, wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight on a dry weight basis.

According to the present invention there is provided an aerosol-generating article comprising: a first aerosol-generating segment comprising a first aerosol-generating substrate; and a second aerosol-generating segment comprising a second aerosol-generating substrate.

In a preferred embodiment, there is provided an aerosol-generating article comprising a first aerosol-generating segment comprising a first aerosol-generating substrate; a second aerosol-generating segment at a location upstream of the first aerosol-generating segment and comprising a second aerosol-generating substrate, wherein the second aerosolgenerating substrate has a higher aerosol former content than the first aerosol-generating substrate, and wherein the second aerosol-generating substrate has a higher density than the first aerosol-generating substrate.

In a preferred embodiment, there is provided an aerosol-generating article comprising an aerosol-generating rod for producing an inhalable aerosol upon heating, the aerosolgenerating rod comprising: a first aerosol-generating segment comprising a first aerosolgenerating substrate, wherein the first aerosol-generating substrate comprises at least one aerosol former and wherein the aerosol former content of the first aerosol-generating substrate is less than 30 percent by weight, on a dry weight basis; and a second aerosol-generating segment at a location upstream of the first aerosol-generating segment and comprising a second aerosol-generating substrate, wherein the second aerosol-generating substrate comprises at least one aerosol former and wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight, on a dry weight basis.

In a preferred embodiment there is provided an aerosol-generating article comprising an aerosol-generating rod for producing an inhalable aerosol upon heating, the aerosolgenerating rod comprising: a first aerosol-generating segment comprising a first aerosolgenerating substrate, wherein the first aerosol-generating substrate comprises at least one aerosol former and wherein the aerosol former content of the first aerosol-generating substrate is less than 30 percent by weight; and a second aerosol-generating segment at a location upstream of the first aerosol-generating segment and comprising a second aerosol-generating substrate, wherein the second aerosol-generating substrate comprises at least one aerosol former, wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight, on a dry weight basis and wherein the density of the second aerosol-generating substrate is at least 1 .2 times the density of the first aerosol-generating substrate.

In a preferred embodiment there is provided an aerosol-generating article comprising an aerosol-generating rod for producing an inhalable aerosol upon heating, the aerosolgenerating rod comprising: a first aerosol-generating segment comprising a first aerosolgenerating substrate, wherein the first aerosol-generating substrate comprises at least one aerosol former, wherein the aerosol former content of the first aerosol-generating substrate is less than 30 percent by weight and wherein the first aerosol-generating substrate has a density of less than 400 mg per cubic centimetre; and a second aerosol-generating segment at a location upstream of the first aerosol-generating segment and comprising a second aerosolgenerating substrate, wherein the second aerosol-generating substrate comprises at least one aerosol former, wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight, on a dry weight basis and wherein the density of the second aerosol-generating substrate is greater than 500 mg per cubic centimetre. In a preferred embodiment there is provided an aerosol-generating article comprising an aerosol-generating rod for producing an inhalable aerosol upon heating, the aerosolgenerating rod comprising: a first aerosol-generating segment comprising a first aerosolgenerating substrate, wherein the first aerosol-generating substrate comprises at least one aerosol former and wherein the aerosol former content of the first aerosol-generating substrate is less than 30 percent by weight; and a second aerosol-generating segment at a location upstream of the first aerosol-generating segment and comprising a second aerosol-generating substrate, wherein the second aerosol-generating substrate comprises at least one aerosol former, wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight, on a dry weight basis and wherein the ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment is no more than 0.5.

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

As used herein, the term “aerosol-generating device” refers to a device comprising a heater element that interacts with the aerosol-generating substrate of the aerosol-generating article to generate an aerosol.

As used herein with reference to the present invention, the term “rod” is used to denote a generally elongate element, preferably a cylindrical element of substantially circular, oval or elliptical cross-section. In the articles of the present invention, the aerosol-generating rod is formed of two or more aerosol-generating segments, which are distinct elements formed of aerosol-generating substrates having a different composition to each other. The aerosolgenerating segments are coaxially combined in order to form the aerosol-generating rod.

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

During use, air is drawn through the aerosol-generating article in the longitudinal direction. The term “transverse” refers to the direction that is perpendicular to the longitudinal axis. Any reference to the “cross-section” of the aerosol-generating article or a component of the aerosol-generating article refers to the transverse cross-section unless stated otherwise. The term “length” denotes the dimension of a component of the aerosol-generating article in the longitudinal direction. For example, it may be used to denote the dimension of the rod or of the elongate tubular elements in the longitudinal direction.

Unless specified otherwise, the aerosol former content of the first aerosol-generating substrate is in percent by weight, on a dry weight basis. The aerosol former content of the first aerosol-generating substrate is based on the weight of the first aerosol-generating substrate.

Unless specified otherwise, the aerosol former content of the second aerosol-generating substrate is in percent by weight, on a dry weight basis. The aerosol former content of the second aerosol-generating substrate is based on the weight of the second aerosol-generating substrate.

The present invention relates to aerosol-generating articles having an aerosolgenerating rod with two distinct segments of aerosol-generating substrate, which have differing aerosol former contents to each other. In particular, the first and second aerosolgenerating substrates are adapted such that the second aerosol-generating substrate, which is provided in the second, upstream aerosol-generating segment, has a higher aerosol former content than the first aerosol-generating substrate, which is provided in the first, downstream aerosol-generating segment. The first and second aerosol-generating substrates may be adapted such that the second aerosol-generating substrate, which is provided in the second, upstream aerosol-generating segment, has a significantly higher aerosol former content than the first aerosol-generating substrate, which is provided in the first, downstream aerosolgenerating segment.

The provision of such an arrangement, for example with an upstream segment of aerosol-generating substrate having a relatively high aerosol former content (above 40 percent by weight) and a downstream segment of aerosol-generating substrate having a relatively low aerosol former content (below 30 percent by weight), provides an improved delivery of aerosol upon heating of the aerosol-generating rod. The first aerosol-generating substrate, which has a lower level of aerosol former, will heat up faster due to the lower thermal inertia and will begin to produce a measurable amount of aerosol within a relatively short time. The time to first puff can therefore be minimised and aerosol can be delivered to the consumer relatively quickly after the commencement of heating. The first aerosol-generating substrate will release a higher level of aerosol than the second aerosol-generating substrate during the earlier puffs in the puff profile but due to the lower level of aerosol former, will become depleted relatively quickly.

The second aerosol-generating substrate, which has a significantly higher level of aerosol former, will take a longer time after the commencement of heating to begin to release a measurable amount of aerosol but will continue to release aerosol after the release of aerosol from the first aerosol-generating substrate has finished. The second aerosolgenerating substrate will therefore release a higher level of aerosol than the first aerosolgenerating substrate during the later puffs in the puff profile. In combination, the first and second aerosol-generating segments are therefore able to provide a highly consistent and more sustained delivery of aerosol over time. The total duration of time over which the aerosol is delivered can also be increased, to provide an overall longer experience to the consumer.

Once the aerosol has been generated from the first aerosol-generating substrate, the remaining depleted first aerosol-generating segment will typically have a relatively low weight and density. This advantageously means that the first aerosol-generating segment provides a minimal level of filtration of the aerosol generated from the second, upstream aerosolgenerating segment during the later puffs. This enables the delivery of aerosol to the consumer to be maintained during the entire experience.

The use of two distinct aerosol-generating segments within the aerosol-generating rod may also be used to more precisely control the delivery of active compounds such as nicotine and flavours to the consumer over the course of the experience, as the composition of the two aerosol-generating substrates can be adapted so that they are different to each other. The combination of two different aerosol-generating substrates may also enable the generation of more complex aerosols, with potentially novel combinations of active compounds.

The beneficial effects provided by the use of two distinct aerosol-generating segments can be achieved whilst still using a single heater element to heat both segments, such that the device for heating the aerosol-generating article does not need to be adapted.

The use of dual aerosol-generating segments within the aerosol-generating rod does not necessarily affect the overall construction of the aerosol-generating article. The aerosolgenerating rod comprising the dual segments can therefore advantageously be incorporated into existing high speed production lines, without the need for significant modification of the apparatus of techniques.

As defined above, an aerosol-generating article in accordance with the present invention comprises an aerosol-generating rod. Further, an aerosol-generating article in accordance with the present invention typically comprises one or more elements provided downstream of the aerosol-generating rod. Where present, the one or more elements downstream of the aerosol-generating rod form the downstream section of the aerosolgenerating article. An aerosol-generating article in accordance with the present invention may additionally comprise one or more elements provided upstream of the aerosol-generating substrate. Where present, the one or more elements upstream of the aerosol-generating rod form the upstream section of the aerosol-generating article.

The aerosol-generating rod comprises the first aerosol-generating segment and the second aerosol-generating segment. As described below, it may additionally comprise one or more further aerosol-generating segments. The second aerosol-generating segment is provided upstream of the first aerosol-generating segment. Preferably, the second aerosolgenerating segment is adjacent to the first aerosol-generating segment. Preferably, the downstream end of the second aerosol-generating segment abuts the upstream end of the first aerosol-generating segment. Preferably, substantially the whole surface of the downstream end of the second aerosol-generating segment abuts the upstream end of the first aerosol-generating segment. The second aerosol-generating segment may extend to the upstream end of the aerosol-generating article. Alternatively, one or more additional elements may be provided upstream of the second aerosol-generating segment, as described in more detail below.

The first and second aerosol-generating substrates forming the first and second aerosol-generating segments, respectively, have different compositions to each other. In particular, according to the invention, the second aerosol-generating substrate has a significantly higher level of aerosol former than the first aerosol-generating substrate. The level of aerosol former is important because it controls the amount of aerosol that can be generated from the aerosol-generating substrate and also the speed at which aerosol will be generated upon heating. Upon volatilisation, the aerosol former will convey other vaporised compounds released from the aerosol-generating substrate upon heating, such as nicotine and flavourants, into an aerosol.

Suitable aerosol formers for inclusion in the first and second aerosol-generating substrates 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 first and second aerosol-generating substrates may comprise the same aerosol former (or aerosol formers) as each other, or different aerosol formers may be used.

The first aerosol-generating substrate preferably has an aerosol former content of no more than 30 percent by weight on a dry weight basis. More preferably, the first aerosolgenerating substrate has an aerosol former content of no more than 25 percent by weight on a dry weight basis. More preferably, the first aerosol-generating substrate has an aerosol former content of no more than 20 percent by weight on a dry weight basis.

Preferably, the first aerosol-generating substrate has an aerosol former content of at least 5 percent by weight on a dry weight basis. More preferably, the first aerosol-generating substrate has an aerosol former content of at least 10 percent by weight on a dry weight basis. More preferably, the first aerosol-generating substrate has an aerosol former content of at least 15 percent by weight on a dry weight basis. For example, the aerosol former content of the first aerosol-generating substrate may be between 5 percent and 30 percent by weight, or between 10 percent and 25 percent by weight, or between about 15 percent and about 20 percent by weight, on a dry weight basis. The aerosol former content of the first aerosol-generating substrate is therefore relatively low.

Preferably, the first aerosol-generating substrate comprises glycerol as aerosol former. For example, the first aerosol-generating substrate may comprise between 5 percent and 30 percent by weight of glycerol, or between 10 percent and 25 percent by weight of glycerol, or between 15 percent and 20 percent by weight of glycerol, on a dry weight basis.

The second aerosol-generating substrate preferably has a higher aerosol former content than the first aerosol-generating substrate. Preferably, the second aerosol-generating substrate has an aerosol former content of at least 40 percent by weight on a dry weight basis. More preferably, the second aerosol-generating substrate has an aerosol former content of at least 45 percent by weight on a dry weight basis. More preferably, the second aerosolgenerating substrate has an aerosol former content of at least 50 percent by weight on a dry weight basis.

Preferably, the second aerosol-generating substrate has an aerosol former content of no more than 80 percent by weight on a dry weight basis. More preferably, the second aerosol-generating substrate has an aerosol former content of no more than 75 percent by weight on a dry weight basis. More preferably, the second aerosol-generating substrate has an aerosol former content of no more than 70 percent by weight on a dry weight basis.

For example, the aerosol former content of the second aerosol-generating substrate may be between 40 percent and 80 percent by weight, or between 45 percent and 75 percent by weight, or between 50 percent and 70 percent by weight, on a dry weight basis. The aerosol former content of the second aerosol-generating substrate is therefore relatively high.

Preferably, the second aerosol-generating substrate comprises glycerol as aerosol former. For example, the second aerosol-generating substrate may comprise between 40 percent and 80 percent by weight of glycerol, or between 45 percent and 75 percent by weight of glycerol, or between 50 percent and 70 percent by weight of glycerol, or between 15 percent and 20 percent by weight of glycerol, on a dry weight basis.

Preferably, the aerosol former content of the second aerosol-generating substrate is at least 15 percent by weight higher than the aerosol former content of the first aerosolgenerating substrate, on a dry weight basis. For example, if the first aerosol-generating substrate has an aerosol former content of 15 percent by weight, the second aerosolgenerating substrate preferably has an aerosol former content of at least 30 percent by weight. More preferably, the aerosol former content of the second aerosol-generating substrate is at least 20 percent by weight higher than the aerosol former content of the first aerosolgenerating substrate, on a dry weight basis. More preferably, the aerosol former content of the second aerosol-generating substrate is at least 25 percent by weight higher than the aerosol former content of the first aerosol-generating substrate, on a dry weight basis. The aerosol former content of the second aerosol-generating substrate may be up to 60 percent by weight higher than the aerosol former content of the first aerosol-generating substrate.

Preferably, the aerosol former content of the second aerosol-generating substrate is at least 1.2 times the aerosol former content of the first aerosol-generating substrate, on a dry weight basis. More preferably, the aerosol former content of the second aerosol-generating substrate is at least 1.5 times the aerosol former content of the first aerosol-generating substrate, on a dry weight basis. More preferably, the aerosol former content of the second aerosol-generating substrate is at least twice the aerosol former content of the first aerosolgenerating substrate, on a dry weight basis. The aerosol former content of the second aerosol-generating substrate may be up to 4 times the aerosol former content of the first aerosol-generating substrate.

Preferably, the glycerol content of the second aerosol-generating substrate is at least 5 precent by weight higher than the glycerol content of the first aerosol-generating substrate, or at least 10 percent by weight higher, or at least 15 percent by weight higher than the glycerol content of the first aerosol-generating substrate, on a dry weight basis. More preferably, the glycerol content of the second aerosol-generating substrate is at least 20 percent by weight higher than the glycerol content of the first aerosol-generating substrate, on a dry weight basis. More preferably, the glycerol content of the second aerosol-generating substrate is at least 25 percent by weight higher than the glycerol content of the first aerosol-generating substrate, on a dry weight basis. The glycerol content of the second aerosol-generating substrate may be up to 60 percent by weight higher than the glycerol content of the first aerosol-generating substrate.

Preferably, the glycerol content of the second aerosol-generating substrate is at least 1 .2 times the glycerol content of the first aerosol-generating substrate, on a dry weight basis. More preferably, the glycerol content of the second aerosol-generating substrate is at least 1 .5 times the glycerol content of the first aerosol-generating substrate, on a dry weight basis. More preferably, the glycerol content of the second aerosol-generating substrate is at least twice the aerosol former content of the first aerosol-generating substrate, on a dry weight basis. The glycerol content of the second aerosol-generating substrate may be up to 3 or 4 times the glycerol content of the first aerosol-generating substrate.

Typically, the first and second aerosol-generating substrates will also differ from each other in other aspects of the composition, form or physical properties. For example, the second aerosol-generating substrate preferably has a higher density than the first aerosolgenerating substrate. The term “density” as used herein in relation to the aerosol-generating substrates refers to the bulk density of the aerosol-generating substrate. This can be calculated by measuring the total weight of the aerosol-generating substrate and dividing this by the volume of the segment of aerosol-generating substrate (excluding any wrapper).

The provision of differing densities between the first and second aerosol-generating substrate can further optimise the speed and consistency of aerosol generation, enhancing the beneficial effects provided by the differing aerosol former contents, as described above.

Preferably, the density of the second aerosol-generating substrate is at least 25 mg per cubic centimetre higher than the density of the first aerosol-generating substrate, or at least 50 mg per cubic centimetre higher than the density of the first aerosol-generating substrate, or at least 75 mg per cubic centimetre higher than the density of the first aerosol-generating substrate, or at least 100 mg per cubic centimetre higher than the density of the first aerosolgenerating substrate. More preferably, the density of the second aerosol-generating substrate is at least 150 mg per cubic centimetre higher than the density of the first aerosol-generating substrate. More preferably, the density of the second aerosol-generating substrate is at least 200 mg per cubic centimetre higher than the density of the first aerosol-generating substrate. The density of the second aerosol-generating substrate may be up to 500 mg per cubic centimetre higher than the density of the first aerosol-generating substrate.

Preferably, the density of the second aerosol-generating substrate is at least 1.05 times the density of the first aerosol-generating substrate, or at least 1.1 times the density of the first aerosol-generating substrate, or at least 1 .2 times the density of the first aerosol-generating substrate. More preferably, the density of the second aerosol-generating substrate is at least 1.3 times the density of the first aerosol-generating substrate, or at least 1.4 times the density of the first aerosol-generating substrate, or at least 1 .5 times the density of the first aerosolgenerating substrate. More preferably, the density of the second aerosol-generating substrate is at least twice the density of the first aerosol-generating substrate. The density of the second aerosol-generating substrate may be up to 4 times the density of the first aerosol-generating substrate.

In preferred embodiments of the invention, the density of the second aerosol-generating substrate is at least 1 .2 times the density of the first aerosol-generating substrate and the aerosol former content of the second aerosol-generating substrate is at least twice the aerosol former content of the first aerosol-generating substrate.

Preferably, the first aerosol-generating substrate has a density of at least 100 mg per cubic centimetre. More preferably, the density of the first aerosol-generating substrate is at least 125 mg per cubic centimetre. More preferably, the density of the first aerosol-generating substrate is at least 150 mg per cubic centimetre. Even more preferably, the density of the first aerosol-generating substrate is at least 200 mg per cubic centimetre. Preferably, the first aerosol-generating substrate has a density of less than 400 mg per cubic centimetre. More preferably, the density of the first aerosol-generating substrate is less than 375 mg per cubic centimetre. More preferably, the density of the first aerosol-generating substrate is less than 350 mg per cubic centimetre. More preferably, the density of the first aerosol-generating substrate is less than 300 mg per cubic centimetre.

For example, the first aerosol-generating substrate may have a density of between 100 mg per cubic centimetre and 400 mg per cubic centimetre, or between 125 mg per cubic centimetre and 375 mg per cubic centimetre, or between 150 mg per cubic centimetre and 350 mg per cubic centimetre, or between 200 mg per cubic centimetre and 300 mg per cubic centimetre.

The first aerosol-generating substrate therefore preferably has a relatively low density. In combination with the relatively low aerosol former content, this further reduces the thermal inertia of the first aerosol-generating substrate so that the first aerosol-generating substrate can quickly be brought up to the temperature needed for aerosol generation. The low density of the first aerosol-generating substrate additionally minimises the filtration effect of the first aerosol-generating substrate on the aerosol generated from the upstream aerosol-generating substrate segment or segments.

Preferably, the second aerosol-generating substrate has a density of at least 500 mg per cubic centimetre. More preferably, the density of the second aerosol-generating substrate is at least 525 mg per cubic centimetre. More preferably, the density of the second aerosolgenerating substrate is at least 550 mg per cubic centimetre. Even more preferably, the density of the second aerosol-generating substrate is at least 600 mg per cubic centimetre.

Preferably, the second aerosol-generating substrate has a density of less than 1000 mg per cubic centimetre. More preferably, the density of the second aerosol-generating substrate is less than 900 mg per cubic centimetre. More preferably, the density of the second aerosol-generating substrate is less than 800 mg per cubic centimetre. More preferably, the density of the second aerosol-generating substrate is less than 750 mg per cubic centimetre.

For example, the second aerosol-generating substrate may have a density of between 500 mg per cubic centimetre and 1000 mg per cubic centimetre, or between 525 mg per cubic centimetre and 900 mg per cubic centimetre, or between 550 mg per cubic centimetre and 880 mg per cubic centimetre, or between 600 mg per cubic centimetre and 750 mg per cubic centimetre.

The second aerosol-generating substrate therefore preferably has a relatively high density. In combination with the relatively high aerosol former content, this further increases the thermal inertia of the second aerosol-generating substrate so that the second aerosolgenerating substrate takes significantly longer to reach the temperature needed for aerosol generation and can therefore deliver aerosol during the later puffs. The high density also enables a relatively high amount of the aerosol former and active compounds to be provided per volume of aerosol-generating substrate, so that the aerosol delivery can be increased both in concentration and in duration.

The first aerosol-generating substrate and the second aerosol-generating substrate may be formed of the same type of substrate as each other. Suitable types of materials for use in the aerosol-generating article of the present invention are described below and include, for example, tobacco cut filler, homogenised tobacco material such as cast leaf, aerosolgenerating films and gel compositions. Preferably, the first aerosol-generating substrate and the second aerosol-generating substrate are different types of material to each other.

Preferably, the first aerosol-generating substrate comprises tobacco material. In certain preferred embodiments, the first aerosol-generating substrate comprises shredded tobacco material. For example, the shredded tobacco material may be in the form of cut filler, as described in more detail below. Alternatively, the shredded tobacco material may be in the form of a shredded sheet of homogenised tobacco material. Suitable homogenised tobacco materials for use in the present invention are described below.

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

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

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

Preferably, the cut filler comprises tobacco plant material comprising lamina of one or more of bright tobacco, dark tobacco, aromatic tobacco and filler tobacco. With reference to the present invention, the term “tobacco” describes any plant member of the genus Nicotiana.

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

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

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

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

Preferably, the aerosol former in the cut filler comprises one or more of glycerol and propylene glycol. The aerosol former may consist of glycerol or propylene glycol or of a combination of glycerol and propylene glycol.

In other preferred embodiments, the first aerosol-generating substrate comprises homogenised plant material, preferably a homogenised tobacco material.

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

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

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

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

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

Where the homogenised plant material is in the form of one or more sheets, as described above, the sheets may be produced by a casting process. Alternatively, 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-generating substrate.

The one or more sheets as described herein may each individually have a grammage of between 100 grams per square metre and 600 grams per square metre.

The one or more sheets as described herein may each individually have a density of from 0.3 grams per cubic centimetre to 1 .3 grams per cubic centimetre, and preferably from 0.7 grams per cubic centimetre to 1 .0 gram per cubic centimetre.

The one or more sheets as described herein may have been one or more of crimped, folded, gathered and pleated.

The one or more sheets of homogenised plant material may be cut into strands as referred to above. In such embodiments, the aerosol-generating substrate comprises 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 homogenised plant material may comprise between 2.5 percent and 95 percent by weight of plant particles, or between 5 percent and 90 percent by weight of plant particles, or between 10 percent and 80 percent by weight of plant particles, or between 15 percent and 70 percent by weight of plant particles, or between 20 percent and 60 percent by weight of plant particles, or between 30 percent and 50 percent by weight of plant particles, on a dry weight basis.

In certain embodiments of the invention, the homogenised plant material is a homogenised tobacco material comprising tobacco particles. Sheets of homogenised tobacco material for use in such embodiments of the invention 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.

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

Preferably, the second aerosol-generating substrate comprises at least 0.5 percent by weight of nicotine on a dry weight basis. More preferably, the second aerosol-generating substrate comprises at least 1 percent by weight of nicotine on a dry weight basis. Even more preferably, the second aerosol-generating substrate comprises at least 2 percent by weight of nicotine on a dry weight basis. In addition, or as an alternative, the second aerosol-generating substrate preferably comprises less than 10 percent by weight of nicotine on a dry weight basis. More preferably, the second aerosol-generating substrate comprises less than 8 percent by weight of nicotine on a dry weight basis. More preferably, the second aerosolgenerating substrate comprises less than 6 percent by weight of nicotine on a dry weight basis.

For example, the second aerosol-generating substrate may comprise between 0.5 percent and 10 percent by weight of nicotine, or between 1 percent and 8 percent by weight of nicotine, or between 2 percent and 6 percent by weight of nicotine, on a dry weight basis.

The second aerosol-generating substrate may be substantially tobacco free.

The second aerosol-generating substrate may be in the form of cut filler, or a homogenised tobacco material, as described above.

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

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

The aerosol former content of the aerosol-generating film is within the ranges defined above for the second aerosol-generating substrate. In the context of the present invention the term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film.

Preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methyl cellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof.

More preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), and combinations thereof.

In particularly preferred embodiments, the cellulose based film-forming agent is HPMC.

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

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

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

The aerosol-generating film may further comprise a carboxymethyl cellulose, preferably sodium carboxymethyl cellulose.

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

The aerosol-generating film preferably comprises nicotine.

In embodiments in which the aerosol-generating film comprises a nicotine base or a nicotine salt, the amounts of nicotine recited herein are the amount of free base nicotine or amount of protonated nicotine, respectively.

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

The aerosol-generating film may comprise one or more monoprotic nicotine salts.

As used herein with reference to the invention, the term “monoprotic nicotine salt” is used to describe a nicotine salt of a monoprotic acid.

Preferably, the aerosol-generating film comprises at least 0.5 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-generating film comprises at least 1 percent by weight of nicotine on a dry weight basis. Even more preferably, the aerosolgenerating film comprises at least 2 percent by weight of nicotine on a dry weight basis. In addition, or as an alternative, the aerosol-generating film preferably comprises less than 10 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-generating film comprises less than 8 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-generating film comprises less than 6 percent by weight of nicotine on a dry weight basis.

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

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

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

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

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

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

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

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

The gel composition preferably comprises at least 50 percent by weight of aerosol former, more preferably at least 60 percent by weight, more preferably at least 70 percent by weight of aerosol former, on a dry weight basis. The gel composition may comprise up to 80 percent by weight of aerosol former. The aerosol former in the gel composition is preferably glycerol. The gel composition preferably includes at least one gelling agent. Preferably, the gel composition includes a total amount of gelling agents in a range from about 0.4 percent by weight to about 10 percent by weight, or from about 0.5 percent by weight to about 8 percent by weight, or from about 1 percent by weight to about 6 percent by weight, or from about 2 percent by weight to about 4 percent by weight, or from about 2 percent by weight to about 3 percent by weight.

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

The term “hydrogen-bond crosslinking gelling agent” refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via hydrogen bonding.

The hydrogen-bond crosslinking gelling agent may include one or more of a galactomannan, gelatin, agarose, or konjac gum, or agar. The hydrogen-bond crosslinking gelling agent may preferably include agar.

The term “ionic crosslinking gelling agent” refers to a gelling agent that forms non- covalent crosslinking bonds or physical crosslinking bonds via ionic bonding.

The ionic crosslinking gelling agent may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan or alginate. The ionic crosslinking gelling agent may preferably include low acyl gellan.

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

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

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

The term “viscosifying agent” refers to a compound that, when added homogeneously into a 25°C, 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of 0.3 percent by weight., increases the viscosity without leading to the formation of a gel, the mixture staying or remaining fluid. The gel composition preferably includes the viscosifying agent in a range from about 0.2 percent by weight to about 5 percent by weight, or from about 0.5 percent by weight to about 3 percent by weight, or from about 0.5 percent by weight to about 2 percent by weight, or from about 1 percent by weight to about 2 percent by weight.

The viscosifying agent may include one or more of xanthan gum, 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 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).

The gel composition preferably comprises some water. The gel composition is more stable when the composition comprises some water.

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

Preferably, where a gel composition is used, the second aerosol-generating 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 used in the present invention may be crimped or shredded.

The porous medium may be in the form of a sheet, thread or tubular element.

The first aerosol-generating segment and the second aerosol-generating segment may have substantially the same length as each other. More preferably, the length of the first aerosol-generating segment is less than the length of the second aerosol-generating segment. This may help to maximise the amount of aerosol that can be generated from the aerosolgenerating rod and the duration of aerosol release.

The ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment is preferably no more than 1. For example, the ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment may be no more than 0.8, no more than 0.6, or no more than 0.5.

The ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment is preferably at least 0.1 . For example, the ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment may be at least 0.2, at least 0.3, or at least 0.4.

The ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment may be between 0.1 and 1 , between 0.2 and 0.8, between 0.3 and 0.6, or between 0.4 and 0.5. The ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment may be about 0.4, or about 0.42.

In preferred embodiments of the invention, the density of the second aerosol-generating substrate is at least 1 .2 times the density of the first aerosol-generating substrate, the aerosol former content of the second aerosol-generating substrate is at least twice the aerosol former content of the first aerosol-generating substrate on a dry weight basis and the ratio of the length of the first aerosol-generating segment to the second aerosol-generating segment is no more than 0.5.

The length of the second aerosol-generating segment is preferably at least 2 millimetres greater than the length of the first aerosol-generating segment. For example, the length of the second aerosol-generating segment may be at least 4 millimetres greater than the length of the first aerosol-generating segment, or at least 6 millimetres greater than the length of the first aerosol-generating article.

The length of the second aerosol-generating segment may be no more than 15 millimetres greater than the length of the first aerosol-generating segment. For example, the length of the second aerosol-generating segment may be no more than 12 millimetres greater than the length of the first aerosol-generating segment, or no more than 10 millimetres greater than the length of the first aerosol-generating segment.

The length of the second aerosol-generating segment may between 2 millimetres and 15 millimetres greater than the length of the first aerosol-generating segment, or between 4 millimetres and 12 millimetres greater than the length of the first aerosol-generating segment, between 6 millimetres and 10 millimetres greater than the length of the first aerosol-generating segment. The length of the second aerosol-generating segment may be about 7 millimetres greater than the length of the first aerosol-generating segment.

In certain preferred embodiments, the first aerosol-generating segment may have a length of at least 2 millimetres or at least 3 millimetres or at least 4 millimetres. In those embodiments, the first aerosol-generating segment may have a length of no more than 8 millimetres or no more than 7 millimetres or no more than 6 millimetres. For example, the first aerosol-generating segment may have a length of between 2 millimetres and 8 millimetres, between 3 millimetres and 7 millimetres, or between 4 millimetres and 6 millimetres. The first aerosol-generating segment may have a length of about 5 millimetres.

In certain preferred embodiments, the second aerosol-generating segment may have a length of at least 8 millimetres or at least 9 millimetres or at least 10 millimetres. In those embodiments, the second aerosol-generating segment may have a length of no more than 16 millimetres or no more than 15 millimetres or no more than 14 millimetres. For example, the second aerosol-generating segment may have a length of between 8 millimetres and 16 millimetres, between 9 millimetres and 15 millimetres, or between 10 millimetres and 14 millimetres. The second aerosol-generating segment may have a length of about 12 millimetres.

The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be at least 10 millimetres. For example, the combined length of the first aerosol-generating segment and the second aerosol-generating segment may be at least 12 millimetres, at least 14 millimetres, or at least 16 millimetres.

The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be no more than 24 millimetres. For example, the combined length of the first aerosol-generating segment and the second aerosol-generating segment may be no more than 22 millimetres, no more than 20 millimetres, or no more than 18 millimetres.

The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be between 10 millimetres and 24 millimetres. For example, the combined length of the first aerosol-generating segment and the second aerosol-generating segment may be between 12 millimetres and 22 millimetres, between 14 millimetres and 20 millimetres, or between 16 millimetres and 18 millimetres. The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be about 17 millimetres.

In other preferred embodiments, the first aerosol-generating segment may have a length of at least 10 millimetres or at least 15 millimetres or at least 18 millimetres. In those embodiments, the first aerosol-generating segment may have a length of no more than 30 millimetres or no more than 25 millimetres or no more than 20 millimetres. For example, the first aerosol-generating segment may have a length of between 10 millimetres and 30 millimetres, between 15 millimetres and 25 millimetres, or between 18 millimetres and 20 millimetres. The first aerosol-generating segment may have a length of about 18.5 millimetres. The first aerosol-generating segment may have a length of about 17 millimetres.

In other preferred embodiments, the second aerosol-generating segment may have a length of at least 10 millimetres, or at least 15 millimetres or at least 18 millimetres. In those embodiments, the second aerosol-generating segment may have a length of no more than 30 millimetres, or no more than 25 millimetres or no more than 20 millimetres. For example, the second aerosol-generating segment may have a length of between 10 millimetres and 30 millimetres, between 15 millimetres and 25 millimetres, or between 18 millimetres and 20 millimetres. The second aerosol-generating segment may have a length of about 18.5 millimetres. The second aerosol-generating segment may have a length of about 17 millimetres.

The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be at least 20 millimetres. For example, the combined length of the first aerosol-generating segment and the second aerosol-generating segment may be at least 25 millimetres, at least 30 millimetres, or at least 35 millimetres.

The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be no more than 55 millimetres. For example, the combined length of the first aerosol-generating segment and the second aerosol-generating segment may be no more than 50 millimetres, no more than 45 millimetres, or no more than 40 millimetres.

The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be between 20 millimetres and 55 millimetres. For example, the combined length of the first aerosol-generating segment and the second aerosol-generating segment may be between 25 millimetres and 50 millimetres, between 30 millimetres and 45 millimetres, or between 35 millimetres and 40 millimetres.

The combined length of the first aerosol-generating segment and the second aerosolgenerating segment may be about 37 millimetres. The combined length of the first aerosolgenerating segment and the second aerosol-generating segment may be about 34 millimetres.

The aerosol-generating rod may further comprise a third aerosol-generating segment, upstream of the second aerosol-generating segment and comprising a third aerosol- generating substrate. For example, the aerosol-generating rod may comprise a third aerosolgenerating segment abutting the upstream end of the second aerosol-generating segment. The inclusion of a third aerosol-generating segment at the upstream end of the aerosolgenerating rod may further enhance the aerosol delivery from the aerosol-generating articles according to the invention.

In some cases, when the aerosol-generating article is fully received within the heating chamber of the aerosol-generating device, the third aerosol-generating segment may be disposed only partially within the heating zone, or the entire length of the third aerosolgenerating segment may be disposed outside the heating zone. In such cases, at least a portion of the third aerosol-generating segment will not be directly heated by the heating element. The third aerosol-generating segment may however be indirectly heated by conduction and can still generate a useful amount of aerosol. In this case, the third aerosolgenerating substrate will typically heat up relatively slowly compared to the first and second aerosol-generating substrates, thereby providing additional aerosol in the later puffs and potentially extending the duration over which aerosol can be delivered.

As the third aerosol-generating substrate may be heated by indirect conduction, it is preferably provided with a relatively low aerosol former content or a relatively low density, or both. For example, the third aerosol-generating substrate preferably has an aerosol former content and density within the ranges defined above for the first aerosol-generating substrate. The teaching provided above in relation to the first aerosol-generating substrate also applies in relation to the third aerosol-generating substrate.

The third aerosol-generating segment may have any length. The third aerosolgenerating segment may have a length of at least 2 millimetres or at least 3 millimetres or at least 4 millimetres. The third aerosol-generating segment may have a length of no more than 8 millimetres or no more than 7 millimetres or no more than 6 millimetres.

For example, the third aerosol-generating segment may have a length of between 2 millimetres and 8 millimetres, between 3 millimetres and 7 millimetres, or between 4 millimetres and 6 millimetres. The third aerosol-generating segment may have a length of between 1 millimetre and 6 millimetres, between 2 millimetres and 5 millimetres, or between 3 millimetres and 4 millimetres. The third aerosol-generating segment may have a length of about 5 millimetres. The third aerosol-generating segment may have a length of about 3.5 millimetres.

The combined length of the first aerosol-generating segment, the second aerosolgenerating segment and the third aerosol-generating segment may be at least 10 millimetres or at least 12 millimetres or at least 14 millimetres or at least 16 millimetres.

The combined length of the first aerosol-generating segment, the second aerosolgenerating segment, and the third aerosol-generating segment may be no more than 24 millimetres or no more than 22 millimetres or no more than 20 millimetres or no more than 18 millimetres.

For example, the combined length of the first aerosol-generating segment, the second aerosol-generating segment and the third aerosol-generating segment may be between 10 millimetres and 24 millimetres or between 12 millimetres and 22 millimetres or between 14 millimetres and 20 millimetres or between 16 millimetres and 18 millimetres. The combined length of the first aerosol-generating segment, the second aerosol-generating segment and the third aerosol-generating segment may be about 17 millimetres.

The combined length of the aerosol-generating segments preferably corresponds to the length of the aerosol-generating rod.

The aerosol-generating rod preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article.

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

The first aerosol-generating segment preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. Preferably, the external diameter of the first aerosol-generating segment is substantially constant along the length of the first aerosol-generating segment.

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

The second aerosol-generating segment preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. Preferably, the external diameter of the second aerosol-generating segment is substantially constant along the length of the first aerosol-generating segment.

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

The third aerosol-generating segment preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. Preferably, the external diameter of the third aerosol-generating segment is substantially constant along the length of the third aerosol-generating segment.

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

Preferably, the first aerosol-generating segment, the second aerosol-generating segment and the third aerosol-generating segment (where present) have substantially the same external diameter as each other.

The average cross-sectional area of the first aerosol-generating segment is preferably at least 50 percent of the average cross-sectional area of the aerosol-generating article, more preferably at least 80 percent of the average cross-sectional area of the aerosol-generating article, more preferably at least 90 percent of the average cross-sectional area of the aerosolgenerating article.

The cross-sectional area of the first aerosol-generating segment at the upstream end thereof is preferably at least 50 percent of the average cross-sectional area of the aerosolgenerating article, more preferably at least 80 percent of the average cross-sectional area of the aerosol-generating article, more preferably at least 90 percent of the average cross- sectional area of the aerosol-generating article.

The average cross-sectional area of the second aerosol-generating segment is preferably at least 50 percent of the average cross-sectional area of the aerosol-generating article, more preferably at least 80 percent of the average cross-sectional area of the aerosolgenerating article, more preferably at least 90 percent of the average cross-sectional area of the aerosol-generating article.

The cross-sectional area of the second aerosol-generating segment at the downstream end thereof is preferably at least 50 percent of the average cross-sectional area of the aerosolgenerating article, more preferably at least 80 percent of the average cross-sectional area of the aerosol-generating article, more preferably at least 90 percent of the average cross- sectional area of the aerosol-generating article.

The cross-sectional area of the first aerosol-generating segment at the upstream end thereof is substantially the same as the cross-section area of the second aerosol-generating segment at the downstream end thereof.

In certain embodiments of the invention, the aerosol-generating article further comprises one or more elongate susceptor elements within the aerosol-generating rod. For example, one or more elongate susceptor elements may be arranged substantially longitudinally within the aerosol-generating rod and in thermal contact with the aerosol-generating substrate. Where the aerosol-generating rod comprises one or more elongate susceptor elements, one or more of the aerosol-generating segments may include a susceptor element extending longitudinally within that element. With such an arrangement, separate susceptor elements may be provided in the first and second aerosol-generating segments.

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

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

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

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

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

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

Preferably, the elongate susceptor element has a length which is the same or shorter than the length of the aerosol-generating segment in which it is incorporated. Preferably, the elongate susceptor element has a same length as the aerosol-generating segment in which it is incorporated.

The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-generating substrate. Preferred susceptor elements comprise a metal or carbon.

A preferred susceptor element may comprise or consist of a ferromagnetic material, for example a ferromagnetic alloy, ferritic iron, or a ferromagnetic steel or stainless steel. A suitable susceptor element may be, or comprise, aluminium. 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 is arranged in thermal contact with the aerosol-generating substrate of the aerosol-generating segment in which the susceptor element is incorporated. Thus, when the susceptor element heats up the aerosol-generating substrate is heated up and an aerosol is formed. Preferably the susceptor element is arranged in direct physical contact with the aerosol-generating substrate, for example within the aerosol-generating substrate.

Preferably, the first aerosol-generating substrate is circumscribed by a first wrapper and wherein the second aerosol-generating substrate is circumscribed by a second wrapper, separate from the first wrapper. Each of the aerosol-generating segment therefore has its own distinct plug wrapper around the respective aerosol-generating substrate.

The aerosol-generating rod, including the first and second aerosol-generating segments may be circumscribed by a further wrapper, which may combine the aerosol-generating segments and retain them in position relative to each other.

The wrapper circumscribing the aerosol-generating rod 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.

The paper wrapper may have a grammage from 15 gsm to 35 gsm, preferably from 20 gsm to 30 gsm.

The paper wrapper may have a thickness from 25 micrometres to 55 micrometres, preferably from 30 micrometres to 50 micrometres, more preferably from 35 micrometres to 45 micrometres.

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 colaminated sheet.

The paper layer of the co-laminated sheet may have a grammage from 35 gsm to 55 gsm, preferably from 40 gsm to 50 gsm.

The paper layer of the co-laminated sheet may have a thickness from 50 micrometres to 80 micrometres, preferably from 55 micrometres to 75 micrometres, more preferably from 60 micrometres to 70 micrometres. The metallic layer of the co-laminated sheet may have a grammage from 12 gsm to 25 gsm, preferably from 15 gsm to 20 gsm.

The metallic layer of the co-laminated sheet may have a thickness from 2 micrometres to 15 micrometres, preferably from 3 micrometres to 12 micrometres, more preferably from 5 micrometres to 10 micrometres.

The wrapper circumscribing the aerosol-generating rod may be a paper wrapper comprising PVOH (polyvinyl alcohol) or silicone (or polysiloxane) (or polysiloxane). Addition of PVOH (polyvinyl alcohol) or silicone (or polysiloxane) may improve the grease barrier properties of the wrapper.

The paper wrapper comprising PVOH or silicone (or polysiloxane) may have a grammage from 20 gsm to 50 gsm, preferably from 25 gsm to 45 gsm, more preferably from 30 gsm to 40 gsm.

The paper wrapper comprising PVOH or silicone (or polysiloxane) may have a thickness from 25 micrometres to 50 micrometres, preferably from 30 micrometres to 45 micrometres, more preferably from 35 micrometres to 40 micrometres.

The wrapper circumscribing the aerosol-generating rod may comprise a flame retardant composition comprising one or more flame retardant compounds. The term “flame retardant compounds” is used herein to describe chemical compounds that, when added to or otherwise incorporated into a carrier substrate, such as paper or plastic compounds, provide the carrier substrate with varying degrees of flammability protection.

A number of suitable flame retardant compounds are known to the skilled person. In particular, several flame retardant compounds and formulations suitable for treating cellulosic materials are known and have been disclosed and may find use in the manufacture of wrappers for aerosol-generating articles in accordance with the present invention.

The wrapper comprising a flame retardant composition may have a grammage from 20 gsm to 45 gsm, preferably from 25 gsm to 40 gsm, more preferably from 30 gsm to 35 gsm.

The wrapper comprising a flame retardant composition may have a thickness of at least 25 micrometres, preferably at least 30 micrometres, even more preferably at least 35 micrometres. The wrapper comprising a flame retardant composition may have a thickness of less than or equal to 50 micrometres, preferably less than or equal to 45 micrometres, even more preferably less than or equal to 40 micrometres.

Aerosol-generating articles according to the present disclosure may further comprise an upstream section located upstream of the aerosol-generating rod. The upstream section is preferably located immediately upstream of the aerosol-generating rod. The upstream section preferably extends between the upstream end of the aerosol-generating article and the aerosol-generating rod. The upstream section may comprise one or more upstream elements located upstream of the aerosol-generating rod. The aerosol-generating articles of the present invention preferably comprise an upstream element located upstream of and adjacent to the aerosol-generating rod. The upstream element advantageously prevents direct physical contact with the upstream end of the aerosol-generating rod. Furthermore, the presence of an upstream element helps to prevent any loss of the substrate, which may be advantageous, for example, if the substrate contains particulate plant material.

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

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

An upstream element may be made of a porous material or may comprise a plurality of openings. This may, for example, be achieved through laser perforation. Preferably, the plurality of openings is distributed homogeneously over the cross-section of the upstream element.

The porosity or permeability of an upstream element may advantageously be designed in order to provide an aerosol-generating article with a particular overall resistance to draw (RTD) without substantially impacting the filtration provided by other portions of the article.

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

In certain preferred embodiments of the invention, it may be desirable to minimise the RTD of an upstream element. For example, this may be the case for articles that are intended to be inserted the cavity of an aerosol-generating device such that the aerosol-generating substrate is externally heated, as described herein. For such articles, it is desirable to provide the article with as low an RTD as possible, so that the majority of the RTD experience by the consumer is provided by the aerosol-generating device and not the article.

The RTD of an upstream element may be less than 30 millimetres H2O, or less than 20 millimetres H2O, or less than 10 millimetres H2O, or less than 5 millimetres H2O, or less than 2 millimetres H2O. The RTD of an upstream element may be at least 0.1 millimetres H2O, or at least 0.25 millimetres H2O or at least 0.5 millimetres H2O.

Preferably, an upstream element has an RTD of less than 2 millimetres H2O per millimetre of length, more preferably less than 1.5 millimetres H2O per millimetre of length, more preferably less than 1 millimetre H2O per millimetre of length, more preferably less than 0.5 millimetres H2O per millimetre of length, more preferably less than 0.3 millimetres H2O per millimetre of length, more preferably less than 0.2 millimetres H2O per millimetre of length.

Preferably, the combined RTD of the upstream section, or upstream element thereof, and the aerosol-generating rod is less than 15 millimetres H2O, more preferably less than 12 millimetres H2O, more preferably less than 10 millimetres H2O.

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

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

Preferably, the diameter of the longitudinal cavity of the hollow tubular segment forming an upstream element is at least 3 millimetres, more preferably at least 3.5 millimetres, more preferably at least 4 millimetres and more preferably at least 4.5 millimetres. Preferably, the diameter of the longitudinal cavity is maximised in order to minimise the RTD of the upstream section, or upstream element thereof.

Preferably, the wall thickness of the hollow tubular segment is less than 2 millimetres, more preferably less than 1.5 millimetres and more preferably less than 1 millimetre.

An upstream element of the upstream section may be made of any material suitable for use in an aerosol-generating article. The upstream element may, for example, be made of a same material as used for one of the other components of the aerosol-generating article, such as the downstream filter segment or the hollow tubular cooling element. Suitable materials for forming the upstream element include filter materials, ceramic, polymer material, cellulose acetate, cardboard, zeolite or aerosol-generating substrate. The upstream element may comprise a plug of cellulose acetate. The upstream element may comprise a hollow acetate tube, or a cardboard tube.

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

Preferably, the upstream section, or an upstream element thereof, has an external diameter that is approximately equal to the external diameter of the aerosol-generating article. Preferably, the external diameter of the upstream section, or an upstream element thereof, is between 5 millimetres and 12 millimetres, more preferably between 6 millimetres and 10 millimetres, more preferably between 7 millimetres and 8 millimetres. In some embodiments, the external diameter of the upstream section may be less than 7 millimetres, for example, between 5 millimetres and 7 millimetres, or between 6 millimetres and 7 millimetres.

Preferably, the upstream section or an upstream element has a length of between 2 millimetres and 10 millimetres, more preferably between 3 millimetres and 8 millimetres, more preferably between 2 millimetres and 6 millimetres. In a particularly preferred embodiment, the upstream section or an upstream element has a length of 5 millimetres.

The upstream section is preferably circumscribed by a wrapper, such as a plug wrap. The wrapper circumscribing the upstream section is preferably a stiff plug wrap, for example, a plug wrap having a basis weight of at least 80 grams per square metre (gsm), or at least 100 gsm, or at least 110 gsm. This provides structural rigidity to the upstream section.

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

Aerosol-generating articles according to the present invention preferably further comprise a downstream section located downstream of the aerosol-generating rod. The downstream section is preferably located immediately downstream of the aerosol-generating rod. The downstream section of the aerosol-generating article preferably extends between the aerosol-generating rod and the downstream end of the aerosol-generating article. The downstream section may comprise one or more elements, each of which will be described in more detail within the present disclosure.

A length of the downstream section may be at least 20 millimetres, or at least 25 millimetres, or at least 30 millimetres.

A length of the downstream section may be less than 70 millimetres, or less than 60 millimetres, or less than 50 millimetres.

For example, a length of the downstream section may be between 20 millimetres and 70 millimetres, or between 25 millimetres and 60 millimetres, or between 30 millimetres and 50 millimetres.

The downstream section of an aerosol-generating article according to the present invention preferably comprises a hollow tubular cooling element provided downstream of the aerosol-generating rod. The hollow tubular cooling element may advantageously provide an aerosol-cooling element for the aerosol-generating article.

The hollow tubular cooling element may be provided immediately downstream of the aerosol-generating rod. In other words, the hollow tubular cooling element may abut a downstream end of the aerosol-generating rod. The hollow tubular cooling element may define an upstream end of the downstream section of the aerosol-generating article. The downstream end of the aerosol-generating article may coincide with the downstream end of the downstream section. In some embodiments, the downstream section of the aerosolgenerating article comprises a single hollow tubular element. In other words, the downstream section of the aerosol-generating article may comprise only one hollow tubular element. In other embodiments, the downstream section comprises two or more hollow tubular elements, as described below.

As used throughout the present disclosure, the term "hollow tubular element" denotes a generally elongate element defining a lumen or airflow passage along a longitudinal axis thereof. In particular, the term "tubular" will be used in the following with reference to a tubular element having a substantially cylindrical cross-section 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 cross-sectional shapes) of the tubular element may be possible. The hollow tubular cooling element may be an individual, discrete element of the aerosol-generating article which has a defined length and thickness.

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

The RTD of a hollow tubular cooling element is preferably less than or equal to 10 millimetres H2O, or less than or equal to 5 millimetres H2O, or less than or equal to 2.5 millimetres H2O, or less than or equal to 2 millimetres H2O, or less than or equal to 1 millimetre H₂O.

The RTD of a hollow tubular cooling element may be at least 0 millimetres H2O, or at least 0.25 millimetres H2O or at least 0.5 millimetres H2O or at least 1 millimetre H2O.

In aerosol-generating articles in accordance with the present invention the overall RTD of the article depends essentially on the RTD of the rod and optionally on the RTD of the downstream and/or upstream elements. This is because the hollow tubular cooling element is substantially empty and, as such, substantially only marginally contribute to the overall RTD of the aerosol-generating article.

The flow channel should therefore be free from any components that would obstruct the flow of air in a longitudinal direction. Preferably, the flow channel is substantially empty and particularly preferably the flow channel is empty.

As will be described in greater detail within the present disclosure, the aerosolgenerating article may comprise a ventilation zone at a location along the downstream section. In some embodiments, the aerosol-generating article may comprise a ventilation zone at a location along the hollow tubular cooling element. Such, or any, ventilation zone may extend through the peripheral wall of the hollow tubular cooling element. As such, fluid communication is established between the flow channel internally defined by the hollow tubular cooling element and the outer environment. The ventilation zone is further described within the present disclosure.

The length of the hollow tubular cooling element may be at least 15 millimetres, or at least 20 millimetres, or at least 25 millimetres, or at least 30 millimetres.

The length of the hollow tubular cooling element may be less than 50 millimetres, or less than 45 millimetres, or less than 40 millimetres.

For example, the length of the hollow tubular cooling element may be between 15 millimetres and 50 millimetres, or between 20 millimetres and 45 millimetres, or between 20 millimetres and 40 millimetres, or between 20 millimetres and 30 millimetres, or between 25 millimetres and 40 millimetres, or between 30 millimetres and 40 millimetres.

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

The wall thickness of the hollow tubular cooling element may between 100 micrometres and 2 millimetres, or between 150 micrometres and 1.5 millimetres, or between 200 micrometres and 1.25 millimetres.

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

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

The hollow tubular cooling element may have an internal diameter. Preferably, the hollow tubular cooling element may have a constant internal diameter along a length of the hollow tubular cooling element. However, the internal diameter of the hollow tubular cooling element may vary along the length of the hollow tubular cooling element.

The hollow tubular cooling element may have an internal diameter of at least 2 millimetres. For example, the hollow tubular cooling element may have an internal diameter of at least 3 millimetres, at least 4 millimetres, or at least 5 millimetres.

The provision of a hollow tubular cooling element having an internal diameter as set out above may advantageously provide sufficient rigidity and strength to the hollow tubular cooling element.

The hollow tubular cooling element may have an internal diameter of no more than 10 millimetres. For example, the hollow tubular cooling element may have an internal diameter of no more than 9 millimetres, no more than 8 millimetres, or no more than 7 millimetres.

The provision of a hollow tubular cooling element having an internal diameter as set out above may advantageously reduce the resistance to draw of the hollow tubular cooling element.

The hollow tubular cooling element may have an internal diameter of between 2 millimetres and 10 millimetres, between 3 millimetres and 9 millimetres, between 4 millimetres and 8 millimetres, or between 5 millimetres and 7 millimetres.

The lumen or cavity of the hollow tubular cooling element may have any cross sectional shape. The lumen of the hollow tubular cooling element may have a circular cross sectional shape.

The hollow tubular cooling element may comprise a paper-based material. The hollow tubular cooling element may comprise at least one layer of paper. The paper may be very rigid paper. The paper may be crimped paper, such as crimped heat resistant paper or crimped parchment paper.

Preferably, the hollow tubular cooling element may comprise cardboard. The hollow tubular cooling element may be a cardboard tube. The hollow tubular cooling element may be formed from cardboard. Advantageously, cardboard is a cost-effective material that provides a balance between being deformable in order to provide ease of insertion of the article into an aerosol-generating device and being sufficiently stiff to provide suitable engagement of the article with the interior of the device. A cardboard tube may therefore provide suitable resistance to deformation or compression during use.

The hollow tubular cooling element may be a paper tube. The hollow tubular cooling element may be a tube formed from spirally wound paper. The hollow tubular cooling element may be formed from a plurality of layers of the paper. The paper may have a basis weight of at least 50 grams per square meter, at least 60 grams per square meter, at least 70 grams per square meter, or at least 90 grams per square meter.

The hollow tubular cooling element may comprise a polymeric material. For example, the hollow tubular cooling element may comprise a polymeric film. The polymeric film may comprise a cellulosic film. The hollow tubular cooling element may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibres. The hollow tube may comprise cellulose acetate tow.

Where the hollow tubular cooling element comprises cellulose acetate tow, the cellulose acetate tow may have a denier per filament of between 2 and 4 and a total denier of between 25 and 40.

In some embodiments, the aerosol-generating article according to the present invention may comprise a ventilation zone at a location along the downstream section. In more detail, in those embodiments wherein the downstream section comprises a hollow tubular cooling element, the ventilation zone may be provided at a location along the hollow tubular cooling element. Alternatively, in those embodiments where the downstream section comprises a downstream hollow tubular element, as described below, the ventilation zone may be provided at a location along the downstream hollow tubular element.

As such, a ventilated cavity is provided downstream of the aerosol-generating rod. This provides several potential technical benefits. First of all, the inventors have found that one such ventilated hollow tubular cooling element provides a particularly efficient cooling of the aerosol. Thus, a satisfactory cooling of the aerosol can be achieved even by means of a relatively short downstream section. Secondly, the inventors have surprisingly found that such rapid cooling of the volatile species released upon heating the aerosol-generating substrate promotes enhances nucleation of aerosol particles.

The ventilation zone may typically comprise a plurality of perforations through the peripheral wall of the hollow tubular cooling element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. In some embodiments, the ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed online 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 25 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 preferably has a ventilation level of at least 25 percent, more preferably at least 30 percent, even more preferably at least 40 percent, even more preferably at least 50 percent.

An aerosol-generating article in accordance with the present invention may have a ventilation level of up to 90 percent. Preferably, an aerosol-generating article in accordance with the present invention has a ventilation level of less than or equal to 80 percent, more preferably less than or equal to 70 percent, even more preferably less than or equal to 60 percent.

Thus, an aerosol-generating article in accordance with the present invention may have a ventilation level from 25 percent to 90 percent, preferably from 30 percent to 80 percent, more preferably from 40 percent to 70 percent, even more preferably from 50 percent to 60 percent.

As discussed in the present disclosure, the downstream section may comprise a downstream filter segment. The downstream filter segment may extend to a downstream end of the downstream section. The downstream filter segment may be located at the downstream end of the aerosol-generating article. The downstream end of the downstream filter segment may define the downstream end of the aerosol-generating article.

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

The downstream filter segment is preferably a solid plug, which may also be described as a ‘plain’ plug and is non-tubular. The filter segment therefore preferably has a substantially uniform transverse cross section.

The downstream filter segment is preferably formed of a fibrous filtration material. The fibrous filtration material may be for filtering the aerosol that is generated from the aerosolgenerating substrate. Suitable fibrous filtration materials would be known to the skilled person. Particularly preferably, the at least one downstream filter segment comprises a cellulose acetate filter segment formed of cellulose acetate tow.

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

The downstream filter segment may optionally comprise a flavourant, which may be provided in any suitable form. For example, the downstream filter segment may comprise one or more capsules, beads or granules of a flavourant, or one or more flavour loaded threads or filaments.

Preferably, the downstream filter segment has a low particulate filtration efficiency. Preferably, the downstream filter segment is circumscribed by a plug wrap. Preferably, the downstream filter segment is unventilated such that air does not enter the aerosolgenerating article along the downstream filter segment.

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

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

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

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

The resistance to draw (RTD) of the downstream section may be at least 0 millimetres H2O. The RTD of the downstream section may be at least 3 millimetres H2O. The RTD of the downstream section may be at least 6 millimetres H2O.

The RTD of the downstream section may be no greater than 12 millimetres H2O. The RTD of the downstream section may be no greater than 11 millimetres H2O. The RTD of the downstream section may be no greater than 10 millimetres H2O.

The resistance to draw (RTD) characteristics of the downstream section may be wholly or mostly attributed to the RTD characteristics of the downstream filter segment of the downstream section. In other words, the RTD of the downstream filter segment of the downstream section may wholly define the RTD of the downstream section.

The resistance to draw (RTD) of the downstream filter segment may be at least 0 millimetres H2O, or at least 3 millimetres H2O, or at least 6 millimetres H2O. The RTD of the downstream filter segment may be no greater than 12 millimetres H2O, or no greater than 11 millimetres H2O, or no greater than 10 millimetres H2O.

As mentioned above, the downstream filter segment may be formed of a fibrous filtration material. The downstream filter segment may be formed of a porous material. The downstream filter segment may be formed of a biodegradable material. The downstream filter segment may be formed of a cellulose material, such as cellulose acetate. For example, a downstream filter segment may be formed from a bundle of cellulose acetate fibres having a denier per filament between 10 and 15. For example, a downstream filter segment formed from relatively low density cellulose acetate tow, such as cellulose acetate tow comprising fibres of 12 denier per filament.

The downstream filter segment may be formed of a polylactic acid based material. The downstream filter segment may be formed of a bioplastic material, preferably a starch-based bioplastic material. The downstream filter segment may be made by injection moulding or by extrusion. Bioplastic-based materials are advantageous because they are able to provide downstream filter segment structures which are simple and cheap to manufacture with a particular and complex cross-sectional profile, which may comprise a plurality of relatively large air flow channels extending through the downstream filter segment material, that provides suitable RTD characteristics.

The length of the downstream filter segment may be at least 5 millimetres, or at least 10 millimetres. The length of the downstream filter segment may be less than 25 millimetres, or less than 20 millimetres. For example, the length of the downstream filter segment may be between 5 millimetres and 25 millimetres, or between 10 millimetres and 25 millimetres, or between 5 millimetres and 20 millimetres, or between 10 millimetres and 20 millimetres.

The downstream section may further comprise one or more additional hollow tubular elements.

In certain embodiments, the downstream section may comprise a hollow tubular support element upstream of the hollow tubular cooling element described above. Preferably, the hollow tubular support element abuts the downstream end of the aerosol-generating rod. Preferably, the hollow tubular support element abuts the upstream end of the hollow tubular cooling element. Preferably, the hollow tubular support element and the hollow tubular cooling element are adjacent to each other and together provide a hollow tubular section within the downstream section.

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

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

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

The hollow tubular support element may have a wall thickness of at least 1 millimetre, preferably at least 1.5 millimetres, more preferably at least 2 millimetres.

The hollow tubular support element may have a length of at least 5 millimetres. Preferably, the support element has a length of at least 6 millimetres, more preferably at least 7 millimetres.

The hollow tubular support element may have a length of less than 15 millimetres. Preferably, the hollow tubular support element has a length of less than 12 millimetres, more preferably less than 10 millimetres.

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

Alternatively or in addition to the hollow tubular support element, the downstream section may further comprise a downstream hollow tubular element downstream of the hollow tubular cooling element. The downstream hollow tubular element may be provided immediately adjacent to the hollow tubular cooling element. Alternatively and preferably, the downstream hollow tubular element is separated from the hollow tubular cooling element by at least one other component. For example, the downstream section may comprise a downstream filter segment between the hollow tubular cooling element and the downstream hollow tubular element.

The downstream hollow tubular element preferably extends to the downstream end of the downstream section. The downstream hollow tubular element therefore preferably extends to the downstream end of the aerosol-generating article. In certain embodiments, an additional downstream hollow tubular element may be provided, so that the downstream section comprises two adjacent downstream hollow tubular elements, downstream of the downstream filter segment.

The RTD of the downstream hollow tubular element may be less than or equal to 10 millimetres H2O, or less than or equal to 5 millimetres H2O, or less than or equal to 2.5 millimetres H2O, or less than or equal to 2 millimetres H2O. Preferably, the RTD of the downstream hollow tubular element is less than or equal to 1 millimetre H2O.

The RTD of the downstream hollow tubular element may be at least 0 millimetres H2O, or at least 0.25 millimetres H2O or at least 0.5 millimetres H2O or at least 1 millimetre H2O.

The flow channel of the downstream hollow tubular element should therefore be free from any components that would obstruct the flow of air in a longitudinal direction. Preferably, the flow channel is substantially empty and particularly preferably the flow channel is empty.

Preferably, the length of the downstream hollow tubular element is at least 3 millimetres, more preferably at least 4 millimetres, more preferably at least 5 millimetres, more preferably at least 6 millimetres.

The length of the downstream hollow tubular element is preferably less than 20 millimetres, more preferably less than 15 millimetres, more preferably less than 12 millimetres and more preferably less than 10 millimetres.

The lumen or cavity of the downstream hollow tubular element may have any cross sectional shape. The lumen of the downstream hollow tubular element may have a circular cross sectional shape.

The downstream hollow tubular element may comprise a paper-based material. The downstream hollow tubular element may comprise at least one layer of paper. The paper may be very rigid paper. The paper may be crimped paper, such as crimped heat resistant paper or crimped parchment paper.

The downstream hollow tubular element may comprise cardboard. The downstream hollow tubular element may be a cardboard tube.

The downstream hollow tubular element may be a paper tube. The downstream hollow tubular element may be a tube formed from spirally wound paper. The downstream hollow tubular element may be formed from a plurality of layers of the paper. The paper may have a basis weight of at least 50 grams per square meter, at least 60 grams per square meter, at least 70 grams per square meter, or at least 90 grams per square meter.

The downstream hollow tubular element may comprise a polymeric material. For example, the downstream hollow tubular element may comprise a polymeric film. The polymeric film may comprise a cellulosic film. The downstream hollow tubular element may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibres. Preferably, the downstream hollow tubular element comprises cellulose acetate tow. For example, in preferred embodiments, the downstream hollow tubular element comprises a hollow acetate tube.

Where the downstream hollow tubular element comprises cellulose acetate tow, the cellulose acetate tow may have a denier per filament of between 2 and 4 and a total denier of between 25 and 40.

Where the downstream section further comprises an additional downstream hollow tubular element, as described above, the additional downstream hollow tubular element may be formed of the same material as the downstream hollow tubular element, or a different material.

In certain preferred embodiments, the downstream section may comprise a ventilation zone at a location on the downstream hollow tubular element. In one example, this ventilation zone at a location on the downstream hollow tubular element may be provided instead of a ventilation zone at a location on the hollow tubular cooling element. In another example, the ventilation zone at a location on the downstream hollow tubular element may be provided in addition to the ventilation zone provided at a location on the hollow tubular cooling element.

The ventilation zone at a location along the downstream hollow tubular element may comprise a plurality of perforations through the peripheral wall of the downstream hollow tubular element. Preferably, the ventilation zone at a location along the downstream hollow tubular element comprises at least one circumferential row of perforations. In some embodiments, the ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed online during manufacturing of the aerosolgenerating article. Preferably, each circumferential row of perforations comprises from 8 to 30 perforations.

The overall RTD of the aerosol-generating article may be at least 10 millimetres H2O. For example, the overall RTD of the aerosol-generating article may be at least 20 millimetres H2O, at least 30 millimetres H2O, at least 35 millimetres H2O, or at least 40 millimetres H2O.

The overall RTD of the aerosol-generating article may be no more than 70 millimetres H2O. For example, the overall RTD of the aerosol-generating article may be no more than 60 millimetres H2O, no more than 55 millimetres H2O, no more than 50 millimetres H2O, or no more than 45 millimetres H2O.

The overall RTD of the aerosol-generating article may be between 10 millimetres H2O and 70 millimetres H2O. For example, the overall RTD of the aerosol-generating article may be between 20 millimetres H2O and 60 millimetres H2O, between 30 millimetres H2O and 55 millimetres H2O, between 35 millimetres H2O and 50 millimetres H2O, or between 40 millimetres H2O and 45 millimetres H2O. The overall RTD of the aerosol-generating article may be between 40 millimetres H2O and 60 millimetres H2O, between 35 millimetres H2O and 40 millimetres H2O, between 45 millimetres H2O and 50 millimetres H2O, or between 55 millimetres H2O and 65 millimetres H₂O.

The overall RTD of the aerosol-generating article may be about 38 millimetres H2O, about 48 millimetres H2O, or about 60 millimetres H2O.

The aerosol-generating article in accordance with the invention may have an overall length of at least 40 millimetres, or at least 50 millimetres, or at least 60 millimetres.

An overall length of an aerosol-generating article in accordance with the invention may be less than or equal to 90 millimetres, or less than or equal to 85 millimetres, or less than or equal to 80 millimetres.

In some embodiments, an overall length of the aerosol-generating article is preferably from 40 millimetres to 70 millimetres, more preferably from 45 millimetres to 70 millimetres. In other embodiments, an overall length of the aerosol-generating article is preferably from 40 millimetres to 60 millimetres, more preferably from about 45 millimetres to about 60 millimetres. In further embodiments, an overall length of the aerosol-generating article is preferably from 40 millimetres to 50 millimetres, more preferably from 45 millimetres to 50 millimetres. In an exemplary embodiment, an overall length of the aerosol-generating article is about 45 millimetres.

In alternative embodiments, an overall length of the aerosol-generating article is preferably from 50 millimetres to 90 millimetres, more preferably from 60 millimetres to 90 millimetres, even more preferably from 70 millimetres to 90 millimetres. In other embodiments, an overall length of the aerosol-generating article is preferably from 50 millimetres to 85 millimetres, more preferably from 60 millimetres to 85 millimetres, even more preferably from 70 millimetres to 85 millimetres. In further embodiments, an overall length of the aerosolgenerating article is preferably from 50 millimetres to 80 millimetres, more preferably from 60 millimetres to 80 millimetres, even more preferably from 70 millimetres to 80 millimetres. In an exemplary embodiment, an overall length of the aerosol-generating article is 75 millimetres.

The aerosol-generating article may have an external diameter of at least 5 millimetres, or at least 6 millimetres, or at least 7 millimetres.

The aerosol-generating article may have an external diameter of less than or equal to about 12 millimetres, or less than or equal to about 10 millimetres, or less than or equal to about 8 millimetres.

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

The external diameter of the aerosol-generating article may be substantially constant over the whole length of the article. As an alternative, different portions of the aerosolgenerating article may have different external diameters.

In particularly preferred embodiments, one or more of the components of the aerosolgenerating article are individually circumscribed by their own wrapper.

Preferably, at least one of the components of the aerosol-generating article is wrapped in a hydrophobic wrapper.

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

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

By way of example, the paper layer may comprise PVOH (polyvinyl alcohol) or silicon. The PVOH may be applied to the paper layer as a surface coating, or the paper layer may comprise a surface treatment comprising PVOH or silicon.

The present disclosure also relates to an aerosol-generating system comprising an aerosol-generating device having a distal end and a mouth end. The aerosol-generating device may comprise a body. The body or housing of the aerosol-generating device may define a device cavity for removably receiving the aerosol-generating article at the mouth end of the device. The aerosol-generating device may comprise a heating element or heater for heating the aerosol-generating substrate when the aerosol-generating article is received within the device cavity.

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

The expression “received within” may refer to the fact that a component or element is fully or partially received within another component or element. For example, the expression “aerosol-generating article is received within the device cavity” refers to the aerosol-generating article being fully or partially received within the device cavity of the aerosol-generating article. When the aerosol-generating article is received within the device cavity, the aerosolgenerating article may abut the distal end of the device cavity. When the aerosol-generating article is received within the device cavity, the aerosol-generating article may be in substantial proximity to the distal end of the device cavity. The distal end of the device cavity may be defined by an end-wall.

The length of the device cavity may be between 15 millimetres and 80 millimetres, or between 20 millimetres and 70 millimetres, or between 25 millimetres and 60 millimetres, or between 25 millimetres and 50 millimetres.

The length of the device cavity may be between 25 millimetres and 29 millimetres, or between 26 millimetres and 29 millimetres, or between 27 millimetres or 28 millimetres.

The length of the device cavity (or heating chamber) may be the same as or greater than the length of the aerosol-generating rod. The length of the device cavity may be the same as or greater than the combined length of the upstream section or element and aerosolgenerating rod. Preferably, the length of the device cavity is such that at least 75 percent of the length of the aerosol-generating rod is inserted or received within the device cavity, when the aerosol-generating article is received with the aerosol-generating device. More preferably, the length of the device cavity is such that at least 80 percent of the length of the aerosolgenerating rod is inserted or received within the device cavity, when the aerosol-generating article is received with the aerosol-generating device. More preferably, the length of the device cavity is such that at least 90 percent of the length of the aerosol-generating rod is inserted or received within the device cavity, when the aerosol-generating article is received with the aerosol-generating device. This maximises the length of the aerosol-generating rod along which the aerosol-generating substrate can be heated during use, thereby optimising the generation of aerosol from the aerosol-generating substrate and reducing tobacco waste.

The length of the device cavity may be such that the downstream section or a portion thereof is configured to protrude from the device cavity, when the aerosol-generating article received within the device cavity. The length of the device cavity may be such that a portion of the downstream section (such as the hollow tubular cooling element or downstream filter segment) is configured to protrude from the device cavity, when the aerosol-generating article received within the device cavity. The length of the device cavity may be such that a portion of the downstream section (such as the hollow tubular cooling element or downstream filter segment) is configured to be received within the device cavity, when the aerosol-generating article received within the device cavity.

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

A diameter of the device cavity may be between 4 millimetres and 10 millimetres. A diameter of the device cavity may be between 5 millimetres and 9 millimetres. A diameter of the device cavity may be between 6 millimetres and 8 millimetres. A diameter of the device cavity may be between 6 millimetres and 7 millimetres.

A diameter of the device cavity may be substantially the same as or greater than a diameter of the aerosol-generating article. A diameter of the device cavity may be the same as a diameter of the aerosol-generating article in order to establish a tight fit with the aerosolgenerating article.

The device cavity may be configured to establish a tight fit with an aerosol-generating article received within the device cavity. Tight fit may refer to a snug fit. The aerosolgenerating device may comprise a peripheral wall. Such a peripheral wall may define the device cavity, or heating chamber. The peripheral wall defining the device cavity may be configured to engage with an aerosol-generating article received within the device cavity in a tight fit manner, so that there is substantially no gap or empty space between the peripheral wall defining the device cavity and the aerosol-generating article when received within the device.

Such a tight fit may establish an airtight fit or configuration between the device cavity and an aerosol-generating article received therein.

With such an airtight configuration, there would be substantially no gap or empty space between the peripheral wall defining the device cavity and the aerosol-generating article for air to flow through.

The tight fit with an aerosol-generating article may be established along the entire length of the device cavity or along a portion of the length of the device cavity.

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

The air-flow channel of the aerosol-generating device may be defined within, or by, the peripheral wall of the housing of the aerosol-generating device. In other words, the air-flow channel of the aerosol-generating device may be defined within the thickness of the peripheral wall or by the inner surface of the peripheral wall, or a combination of both. The air-flow channel may partially be defined by the inner surface of the peripheral wall and may be partially defined within the thickness of the peripheral wall. The inner surface of the peripheral wall defines a peripheral boundary of the device cavity.

The air-flow channel of the aerosol-generating device may extend from an inlet located at the mouth end, or proximal end, of the aerosol-generating device to an outlet located away from mouth end of the device. The air-flow channel may extend along a direction parallel to the longitudinal axis of the aerosol-generating device.

The heater may be any suitable type of heater. Preferably, in the present invention, the heater is an external heater.

Preferably, the heater may externally heat the aerosol-generating article when received within the aerosol-generating device. Such an external heater may circumscribe the aerosolgenerating article when inserted in or received within the aerosol-generating device.

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

The heater may comprise at least one heating element. The at least one heating element may be any suitable type of heating element. In some embodiments, the device comprises only one heating element. In some embodiments, the device comprises a plurality of heating elements.

Suitable materials for forming the at least one resistive heating element include but are not limited to: semiconductors such as doped ceramics, electrically ‘conductive’ ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum and metals from the platinum group. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetai® and iron- manganese-aluminium based alloys. In some embodiments, the at least one resistive heating element comprises one or more stamped portions of electrically resistive material, such as stainless steel. Alternatively, the at least one resistive heating element may comprise a heating wire or filament, for example a Ni- Cr (Nickel-Chromium), platinum, tungsten or alloy wire.

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

The electrically insulating substrate may comprise any suitable material. For example, the electrically insulating substrate may comprise one or more of: paper, glass, ceramic, anodized metal, coated metal, and Polyimide. The ceramic may comprise mica, Alumina (AI2O3) or Zirconia (ZrC>2). Preferably, the electrically insulating substrate has a thermal conductivity of less than or equal to about 40 Watts per metre Kelvin, preferably less than or equal to about 20 Watts per metre Kelvin and ideally less than or equal to about 2 Watts per metre Kelvin.

The heater may comprise a heating element comprising a rigid electrically insulating substrate with one or more electrically conductive tracks or wire disposed on its surface. The size and shape of the electrically insulating substrate may allow it to be inserted directly into an aerosol-generating substrate. If the electrically insulating substrate is not sufficiently rigid, the heating element may comprise a further reinforcement means. A current may be passed through the one or more electrically conductive tracks to heat the heating element and the aerosol-generating substrate.

In some embodiments, the heater comprises an inductive heating arrangement. The inductive heating arrangement may comprise an inductor coil and a power supply configured to provide high frequency oscillating current to the inductor coil. As used herein, a high frequency oscillating current means an oscillating current having a frequency of between about 500 kHz and about 30 MHz. The heater may advantageously comprise a DC/AC inverter for converting a DC current supplied by a DC power supply to the alternating current. The inductor coil may be arranged to generate a high frequency oscillating electromagnetic field on receiving a high frequency oscillating current from the power supply. The inductor coil may be arranged to generate a high frequency oscillating electromagnetic field in the device cavity. In some embodiments, the inductor coil may substantially circumscribe the device cavity. The inductor coil may extend at least partially along the length of the device cavity.

The heater may comprise an inductive heating element. The inductive heating element may be a susceptor element. A susceptor element may be arranged such that, when the aerosol-generating article is received in the cavity of the aerosol-generating device, the oscillating electromagnetic field generated by the inductor coil induces a current in the susceptor element, causing the susceptor element to heat up. In these embodiments, the aerosol-generating device is preferably capable of generating a fluctuating electromagnetic field having a magnetic field strength (H-field strength) of between 1 and 5 kilo amperes per metre (kA m), preferably between 2 and 3 kA/m, for example about 2.5 kA/m. The electrically- operated aerosol-generating device is preferably capable of generating a fluctuating electromagnetic field having a frequency of between 1 and 30 MHz, for example between 1 and 10 MHz, for example between 5 and 7 MHz.

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

The susceptor element may comprise any suitable material, as described above in relation to a susceptor element incorporated within the aerosol-generating rod.

In some embodiments the aerosol-generating device may comprise at least one resistive heating element and at least one inductive heating element. In some embodiments the aerosol-generating device may comprise a combination of resistive heating elements and inductive heating elements.

During use, the heater may be controlled to operate within a defined operating temperature range, below a maximum operating temperature. An operating temperature range between about 150 degrees Celsius and about 300 degrees Celsius in the heating chamber (or device cavity) is preferable. The operating temperature range of the heater may be between about 150 degrees Celsius and about 250 degrees Celsius.

The aerosol-generating device may comprise a power supply. The power supply may be a DC power supply. In some embodiments, the power supply is a battery. 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-iron-phosphate or a lithium-polymer battery. However, in some embodiments the power supply may be another form of charge storage device, such as a capacitor. The power supply may require recharging and may have a capacity that allows for the storage of enough energy for one or more user operations, for example one or more aerosol-generating experiences.

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: an aerosol-generating rod for producing an inhalable aerosol upon heating, the aerosol-generating rod comprising: a first aerosol- generating segment comprising a first aerosol-generating substrate and a second aerosolgenerating segment located upstream of the first aerosol-generating segment and comprising a second aerosol-generating substrate.

EX2. An aerosol-generating article according to example EX1 , wherein the first aerosolgenerating substrate comprises aerosol former and wherein the aerosol former content of the first aerosol-generating substrate is no more than 30 percent by weight on a dry weight basis. EX3. An aerosol-generating article according to example EX1 or EX2, wherein the second aerosol-generating substrate comprises aerosol former and wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight on a dry weight basis.

EX4. An aerosol-generating article according to example EX3, wherein the second aerosolgenerating substrate comprises at least 50 percent by weight of glycerol.

EX5. An aerosol-generating article according to any of examples EX2 to EX4, wherein the aerosol former content of the second aerosol-generating substrate is at least 15 percent higher than the aerosol former content of the first aerosol-generating substrate.

EX6. An aerosol-generating article according to any of examples EX2 to EX5, wherein the aerosol former content of the second aerosol-generating substrate is at least 1.2 times the aerosol former content of the first aerosol-generating substrate.

EX7. An aerosol-generating article according to any of examples EX2 to EX6, wherein the aerosol former content of the first aerosol-generating substrate is between 5 percent and 30 percent by weight on a dry weight basis.

EX8. An aerosol-generating article according to any of examples EX2 to EX7, wherein the aerosol former content of the second aerosol-generating substrate is between 40 percent and 80 percent by weight on a dry weight basis.

EX9. An aerosol-generating article according to any preceding example, wherein the second aerosol-generating substrate has a higher aerosol former content than the first aerosolgenerating substrate.

EX10. An aerosol-generating article according to any preceding example, wherein the second aerosol-generating substrate has a higher density than the first aerosol-generating substrate. EX11. An aerosol-generating article according to example EX10, wherein the density of the second aerosol-generating substrate is at least 100 mg per cubic centimetre higher than the density of the first aerosol-generating substrate.

EX12. An aerosol-generating article according to any of examples EX9 to EX11 , wherein the first aerosol-generating substrate has a density of less than 400 mg per cubic centimetre.

EX13. An aerosol-generating article according to example EX12, wherein the first aerosolgenerating substrate has a density of between 100 mg per cubic centimetre and 400 mg per cubic centimetre. EX14. An aerosol-generating article according to any of examples EX9 to EX13, wherein the second aerosol-generating substrate has a density of at least 500 mg per cubic centimetre.

EX15. An aerosol-generating article according to example EX14, wherein the second aerosolgenerating substrate has a density of between 500 mg per cubic centimetre and 1000 mg per cubic centimetre.

EX16. An aerosol-generating article according to any of examples EX9 to EX15, wherein the density of the second aerosol-generating substrate is at least 1.2 times the density of the first aerosol-generating substrate.

EX17. An aerosol-generating article according to any preceding example, wherein the first aerosol-generating substrate comprises shredded tobacco material.

EX18. An aerosol-generating article according to example EX17, wherein the first aerosolgenerating substrate comprises tobacco cut filler.

EX19. An aerosol-generating article according to example EX17, wherein the first aerosolgenerating substrate comprises a shredded sheet of homogenised tobacco material.

EX20. An aerosol-generating article according to example EX19, wherein the second aerosolgenerating substrate comprises an aerosol-generating film.

EX21. An aerosol-generating article according to example EX20, wherein the aerosolgenerating film comprises a cellulosic film forming agent, nicotine and the aerosol former.

EX22. An aerosol-generating article according to example EX21 , wherein the aerosolgenerating film further comprises a cellulose based strengthening agent.

EX23. An aerosol-generating article according to example EX21 or EX22, wherein the aerosol-generating film further comprises a carboxymethyl cellulose.

EX24. An aerosol-generating article according to any of examples EX20 to EX23, wherein the aerosol-generating film further comprises an acid.

EX25. An aerosol-generating article according to any of examples EX20 to EX24, wherein the aerosol-generating film is substantially tobacco free.

EX26. An aerosol-generating article according to any of examples EX1 to EX19, wherein the second aerosol-generating substrate comprises a gel composition comprising nicotine, at least one gelling agent and the aerosol former.

EX27. An aerosol-generating segment according to any of the preceding examples, wherein the ratio of the length of the first aerosol-generating segment to the length of the second aerosol-generating segment is between 0.3 and 0.6.

EX28. An aerosol-generating article according to any of the preceding examples, wherein the length of the second aerosol-generating segment is at least 4 millimetres greater than the length of the first aerosol-generating article.

EX29. An aerosol-generating article according to any preceding example, wherein the first aerosol-generating substrate is circumscribed by a first wrapper and wherein the second aerosol-generating substrate is circumscribed by a second wrapper, separate from the first wrapper.

EX30. An aerosol-generating article according to any preceding example, wherein the aerosol-generating rod further comprises a third aerosol-generating segment provided upstream of the second aerosol-generating segment and comprising a third aerosolgenerating substrate.

EX31 . An aerosol-generating article according to example EX30, wherein the third aerosolgenerating substrate comprises shredded tobacco material.

EX32. An aerosol-generating article according to example EX30 or EX31 , wherein the third aerosol-generating substrate comprises at least one aerosol former and wherein the aerosol former content of the third aerosol-generating substrate is no more than 30 percent by weight on a dry weight basis.

EX33. An aerosol-generating article according to any preceding example, further comprising a downstream section provided downstream of the aerosol-generating rod.

EX34. An aerosol-generating article according to example EX33, wherein the downstream section extends to a downstream end of the aerosol-generating article.

EX35. An aerosol-generating article according to example EX33 or EX34, wherein the downstream section comprises a hollow tubular cooling element.

EX36. An aerosol-generating article according to example EX35, wherein the hollow tubular cooling element has a length of at least 20 millimetres.

EX37. An aerosol-generating article according to example EX35 or EX36, wherein the downstream section comprises a ventilation zone at a location along the hollow tubular cooling element.

EX38. An aerosol-generating article according to any of examples EX33 to EX37, wherein the downstream section comprises a downstream filter segment.

EX39. An aerosol-generating article according to example EX38, wherein the downstream filter segment is a solid plug.

EX40. An aerosol-generating article according to example EX38 or EX39, wherein the downstream filter segment has a length of at least 5 millimetres.

EX41. An aerosol-generating article according to any of examples EX35 to EX40, wherein the downstream section further comprises a hollow tubular support element upstream of a hollow tubular cooling element.

EX42. An aerosol-generating article according to any of examples EX35 to EX41 , wherein the downstream section further comprises a downstream hollow tubular element downstream of a hollow tubular cooling element.

EX43. An aerosol-generating article according to any preceding example, further comprising an upstream element provided upstream of the aerosol-generating rod. EX44. An aerosol-generating article according to any preceding example, wherein the aerosol-generating article has a ventilation level of at least 40 percent.

EX45. An aerosol-generating article according to any preceding example, wherein the length of the aerosol-generating article is between 40 millimetres and 50 millimetres.

EX46. An aerosol-generating article according to any of examples EX1 to EX 44, wherein the length of the aerosol-generating article is between 70 millimetres and 80 millimetres.

EX47: An aerosol-generating article according to any preceding example, wherein the second aerosol-generating substrate has a higher aerosol former content than the first aerosolgenerating substrate, and wherein the second aerosol-generating substrate has a higher density than the first aerosol-generating substrate.

EX48: An aerosol-generating article according to any preceding example, wherein the second aerosol-generating substrate has a higher aerosol former content than the first aerosolgenerating substrate, and wherein the first aerosol-generating substrate has a density of less than 400 mg per cubic centimetre.

EX49: An aerosol-generating article according to any preceding example, wherein the first aerosol-generating substrate comprises at least one aerosol former and wherein the aerosol former content of the first aerosol-generating substrate is no more than 30 percent by weight, and wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight, on a dry weight basis.

EX50: An aerosol-generating system comprising an aerosol-generating article according to any one of the preceding examples and an aerosol-generating device comprising a heating chamber for receiving the aerosol-generating article and at least a heating element provided at or about the periphery of the heating chamber.

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

Clause 1 : An aerosol-generating article comprising: an aerosol-generating rod for producing an inhalable aerosol upon heating, the aerosol-generating rod comprising: a first aerosolgenerating segment comprising a first aerosol-generating substrate, wherein the first aerosolgenerating substrate comprises at least one aerosol former and wherein the aerosol former content of the first aerosol-generating substrate is no more than 30 percent by weight, on a dry weight basis; and a second aerosol-generating segment at a location upstream of the first aerosol-generating segment and comprising a second aerosol-generating substrate, wherein the second aerosol-generating substrate comprises at least one aerosol former and wherein the aerosol former content of the second aerosol-generating substrate is at least 40 percent by weight, on a dry weight basis. Clause 2: An aerosol-generating article according to clause 1 , wherein the second aerosolgenerating substrate comprises an aerosol-generating film, the aerosol-generating film comprising a cellulosic based film forming agent, nicotine and glycerol, wherein the aerosolgenerating film has a glycerol content of at least 40 percent by weight.

Clause 3. An aerosol-generating article according to clause 2, wherein the aerosol-generating film is substantially tobacco free.

Clause 4: An aerosol-generating article according to any preceding clause, wherein the first aerosol-generating substrate comprises tobacco cut filler.

Clause 5: An aerosol-generating article according to any preceding clause, wherein the second aerosol-generating segment abuts the upstream end of the first aerosol-generating segment.

Clause 6: An aerosol-generating article according to any preceding clause, wherein the second aerosol-generating substrate comprises at least 50 percent by weight of glycerol, on a dry weight basis.

Clause 7: An aerosol-generating article according to any preceding clause, wherein the first aerosol-generating substrate is circumscribed by a first wrapper and wherein the second aerosol-generating substrate is circumscribed by a second wrapper, separate from the first wrapper.

Clause 8: An aerosol-generating article according to any preceding clause, wherein the aerosol former content of the second aerosol-generating substrate is at least 25 percent higher than the aerosol former content of the first aerosol-generating substrate, on a dry weight basis. Clause 9: An aerosol-generating article according to any preceding clause, wherein the aerosol former content of the second aerosol-generating substrate is at least 1.5 times the aerosol former content of the first aerosol-generating substrate, on a dry weight basis.

Clause 10: An aerosol-generating article according to any preceding clause, wherein the ratio of the length of the first aerosol-generating segment to the length of the second aerosolgenerating segment is no more than 0.6.

Clause 11 : An aerosol-generating article according to any preceding clause, wherein the bulk density of the first aerosol-generating substrate is less than 400 mg per cubic centimetre and the bulk density of the second aerosol-generating substrate is greater than 500 mg per cubic centimetre.

Clause 12: An aerosol-generating article according to any preceding clause, further comprising an upstream element provided upstream of the aerosol-generating rod and abutting an upstream end of the second aerosol-generating segment.

Clause 13: An aerosol-generating article according to any preceding clause, further comprising a downstream section provided downstream of the aerosol-generating rod and extending to the downstream end of the aerosol-generating article, wherein the downstream section comprises a hollow tubular cooling element.

Clause 14: An aerosol-generating article according to any preceding clause, wherein the aerosol-generating article has a ventilation level of at least 40 percent.

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

In the following, the invention will be further described with reference to the drawings of the accompanying Figures, wherein:

Figure 1 shows a schematic side perspective view of an aerosol-generating article in accordance with a first embodiment of the invention;

Figure 2 shows a schematic side sectional view of the aerosol-generating article of Figure 1 ;

Figure 3 shows a schematic side sectional view of the aerosol-generating system comprising an aerosol-generating article as shown in Figures 1 and 2 and an aerosolgenerating device;

Figure 4 shows a schematic side sectional view of an aerosol-generating article in accordance with a second embodiment of the invention; and

Figure 5 shows a schematic side sectional view of an aerosol-generating article in accordance with a third embodiment of the invention.

The aerosol-generating article 10 shown in Figure 1 comprises an aerosol-generating rod 12 and a downstream section 14 at a location downstream of the rod 12. Thus, the aerosol-generating article 10 extends from an upstream or distal end 16 - which substantially coincides with an upstream end of the rod 12 - to a downstream or mouth end 18, which coincides with a downstream end of the downstream section 14. The downstream section 14 comprises a hollow tubular cooling element 20 and a downstream filter segment 50.

The aerosol-generating article 10 has an overall length of about 45 millimetres and an external diameter of about 7.2 mm.

The aerosol-generating rod 12 comprises a first aerosol-generating segment 24 and a second aerosol-generating segment 26, coaxially aligned with each other. The second aerosol-generating article 26 is provided upstream of the first aerosol-generating segment 24, abutting the upstream end of the first aerosol-generating segment 24.

The first aerosol-generating segment 24 has a length of 5 millimetres and comprises a first aerosol-generating substrate formed of about 50 mg of shredded tobacco material comprising between 15 percent by weight and 20 percent by weight of glycerol. The density of the first aerosol-generating substrate is about 300 mg per cubic centimetre. The first aerosol-generating segment 24 is individually wrapped by a plug wrap (not shown).

The second aerosol-generating segment 26 has a length of 12 millimetres and comprises a second aerosol-generating substrate formed of shreds of an aerosol-generating film. Example compositions for the aerosol-generating film are shown below in Table 1 :

Table 1 : aerosol-generating film compositions

The second aerosol-generating substrate has a glycerol content of around 50 percent by weight, as shown above, which is therefore over 10 percent higher than the glycerol content of the first aerosol-generating substrate. The density of the second aerosol-generating substrate is above 600 mg per cubic centimetre. The first aerosol-generating segment 24 is individually wrapped by a plug wrap (not shown).

The hollow tubular cooling element 20 of the downstream section 14 is located immediately downstream of the aerosol-generating rod 12, the hollow tubular cooling element 20 being in longitudinal alignment with the rod 12. The upstream end of the hollow tubular cooling element 20 abuts the downstream end of the rod 12.

The hollow tubular cooling element 20 defines a hollow section of the aerosol-generating article 10. The hollow tubular cooling element 20 does not substantially contribute to the overall RTD of the aerosol-generating article. In more detail, an RTD of the hollow tubular cooling element 20 is about 0 mm H2O.

As shown in Figure 2, the hollow tubular cooling element 20 is provided in the form of a hollow cylindrical tube made of cardboard. The hollow tubular cooling element 20 defines an internal cavity 22 that extends all the way from an upstream end of the hollow tubular cooling element 20 to a downstream end of the hollow tubular cooling element 20. The internal cavity 22 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 22.

The hollow tubular cooling element 20 has a length of about 21 millimetres, an external diameter of about 7.2 millimetres, and an internal diameter of about 6.7 millimetres. Thus, a thickness of a peripheral wall of the hollow tubular cooling element 20 is about 0.25 millimetres.

The aerosol-generating article 10 comprises a ventilation zone 30 provided at a location along the hollow tubular cooling element 20. The ventilation zone 30 comprises a circumferential row of openings or perforations circumscribing the hollow tubular cooling element 20. The perforations of the ventilation zone 30 extend through the wall of the hollow tubular cooling element 20, in order to allow fluid ingress into the internal cavity 22 from the exterior of the article 10. A ventilation level of the aerosol-generating article 10 is about 40 percent.

The downstream filter segment 50 extends from the downstream end of the hollow tubular cooling element 20 to the downstream or mouth end of the aerosol-generating article 10. The downstream filter segment 50 has a length of about 7 millimetres. An external diameter of the downstream filter segment 50 is about 7.2 millimetres. The downstream filter segment 50 comprises a low-density, cellulose acetate filter segment. The RTD of the downstream filter segment 50 is about 8 mm H2O. The downstream filter segment 50 may be individually wrapped by a plug wrap (not shown).

As shown in Figures 1 & 2, the article 10 comprises an upstream wrapper 44 circumscribing the aerosol-generating rod 12 and the hollow tubular cooling element 20. The ventilation zone 30 may also comprise a circumferential row of perforations provided on the upstream wrapper 44. The perforations of the upstream wrapper 44 overlap the perforations provided on the hollow tubular cooling element 20. Accordingly, the upstream wrapper 44 overlies the perforations of the ventilation zone 30 provided on the hollow tubular cooling element 20.

The article 10 also comprises a tipping wrapper 52 circumscribing the hollow tubular cooling element 20 and the mouthpiece element 50. The tipping wrapper 52 overlies the portion of the upstream wrapper 44 that overlies the hollow tubular cooling element 20. This way the tipping wrapper 52 effectively joins the mouthpiece element 50 to the rest of the components of the article 10. The width of the tipper wrapper 52 is about 26 millimetres. Additionally, the ventilation zone 30 may comprise a circumferential row of perforations provided on the tipping wrapper 52. The perforations of the tipping wrapper 52 overlap the perforations provided on the hollow tubular cooling element 20 and the upstream wrapper 44. Accordingly, the tipping wrapper 52 overlies the perforations of the ventilation zone 30 provided on the hollow tubular cooling element 20 and the upstream wrapper 44. Figure 3 illustrates an aerosol-generating system 100 comprising an exemplary aerosol-generating device 1 and the aerosol-generating article 10, equivalent to that shown in Figures 1 & 2. Figure 3 illustrates a downstream, mouth end portion of the aerosol-generating device 1 where the device cavity is defined and the aerosol-generating article 10 can be received. The aerosol-generating device 1 comprises a housing (or body) 4, extending between a mouth end 2 and a distal end (not shown). The housing 4 comprises a peripheral wall 6. The peripheral wall 6 defines a device cavity for receiving an aerosol-generating article 10. The device cavity is defined by a closed, distal end and an open, mouth end. The mouth end of the device cavity is located at the mouth end of the aerosol-generating device 1 . The aerosol-generating article 10 is configured to be received through the mouth end of the device cavity and is configured to abut a closed end of the device cavity.

A device air flow channel 5 is defined within the peripheral wall 6. The air-flow channel

5 extends between an inlet 7 located at the mouth end of the aerosol-generating device 1 and the closed end of the device cavity. Air may enter the aerosol-generating substrate 12 via an aperture (not shown) provided at the closed end of the device cavity, ensuring fluid communication between the air flow channel 5 and the aerosol-generating substrate 12.

The aerosol-generating device 1 further comprises a heater (not shown) and a power source (not shown) for supplying power to the heater. A controller (not shown) is also provided to control such supply of power to the heater. The heater is configured to controllably heat the aerosol-generating article 10 during use, when the aerosol-generating article 1 is received within the device 1. The heater is preferably arranged to externally heat the aerosolgenerating substrate 12 for optimal aerosol generation. The ventilation zone 30 is arranged to be exposed when the aerosol-generating article 10 is received within the aerosol-generating device 1.

In the embodiment shown in Figure 3, the device cavity defined by the peripheral wall

6 is 28 millimetres in length. When the article 10 is received within the device cavity, the aerosol-generating rod 12 and an upstream portion of the hollow tubular cooling element 20 are received within the device cavity. Such an upstream portion of the hollow tubular cooling element 20 is 11 millimetres in length. Accordingly, about 28 millimetres of the article 10 is received within the device 1 and about 17 millimetres of the article 10 is located outside of the device 1. In other words, about 17 millimetres of the article 10 protrudes from the device 1 when the article 10 is received therein. Such a length of the article 10 protruding from the device 1 is shown in Figure 3.

Figure 4 shows an alternative embodiment of the present invention. The aerosolgenerating article 110 shown in Figure 4 has a similar structure to the aerosol-generating article 10 shown in Figure 1 and differs only in the following aspects. The aerosol-generating rod 112 comprises a first aerosol-generating segment 124, a second aerosol-generating segment 126 and a third aerosol-generating segment 128, coaxially aligned with each other. The second aerosol-generating segment 126 is provided upstream of the first aerosol-generating segment 124, abutting the upstream end of the first aerosol-generating segment 124. The third aerosol-generating segment 128 is provided upstream of the second aerosol-generating segment 126, abutting the upstream end of the second aerosol-generating segment 126. The third aerosol-generating segment 128 extends to the upstream end of the aerosol-generating article 110.

The first aerosol-generating segment 124 is substantially the same as the first aerosolgenerating segment 24 described above in relation to the aerosol-generating article 10 of Figure 1. The third aerosol-generating segment 128 is substantially the same as the first aerosol-generating segment 124, with the same length and composition.

The second aerosol-generating segment 126 is substantially the same as the second aerosol-generating segment 26 described above in relation to the aerosol-generating article 10 of Figure 1. The aerosol-generating article 110 therefore differs from the aerosolgenerating article 10 of Figure 1 only in the inclusion of the third aerosol-generating segment 128 at the upstream end of the aerosol-generating rod 112.

Figure 5 shows a further alternative embodiment of the present invention. The aerosolgenerating article 210 shown in Figure 5 comprises an aerosol-generating rod 212 and a downstream section 214 at a location downstream of the aerosol-generating rod 212.

The aerosol-generating article 210 has an overall length of about 80 millimetres and an external diameter of about 6.5 millimetres.

The aerosol-generating rod 212 comprises a first aerosol-generating segment 224 and a second aerosol-generating segment 226, coaxially aligned with each other. The second aerosol-generating article 226 is provided upstream of the first aerosol-generating segment 224, abutting the upstream end of the first aerosol-generating segment 224.

The first aerosol-generating segment 224 has a length of about 15 millimetres and comprises a first aerosol-generating substrate formed of shredded tobacco material comprising about 15 percent by weight of glycerol. The bulk density of the first aerosolgenerating substrate is about 250 mg per cubic centimetre. The first aerosol-generating segment 224 is individually wrapped by a plug wrap (not shown).

The second aerosol-generating segment 226 has a length of about 25 millimetres and comprises a second aerosol-generating substrate formed of homogenised tobacco material comprising tobacco particles and above 40 percent by weight of glycerol, on a dry weight basis. The bulk density of the second aerosol-generating substrate is about 600 mg per cubic centimetre. The second aerosol-generating segment 226 is individually wrapped by a plug wrap (not shown). The downstream section 214 comprises a hollow tubular cooling element 220, a downstream filter segment 250 and a downstream hollow tubular element 260.

The hollow tubular cooling element 220 is located immediately downstream of the aerosol-generating rod 212, the hollow tubular cooling element 220 being in longitudinal alignment with the rod 212. The upstream end of the hollow tubular cooling element 220 abuts the downstream end of the rod 212 of aerosol-generating substrate.

The hollow tubular element 220 has a similar form to the hollow tubular cooling element 20 described above in relation to Figure 1 but has a longer length of about 25 millimetres.

The aerosol-generating article 210 comprises a ventilation zone 230 provided at a location along the hollow tubular cooling element 220, as described above in relation to Figure 1. The ventilation zone 230 comprises a circumferential row of openings or perforations circumscribing the hollow tubular cooling element 220. The perforations of the ventilation zone 230 extend through the wall of the hollow tubular element 220, in order to allow fluid ingress into the internal cavity from the exterior of the article 210. A ventilation level of the aerosolgenerating article 210 is about 70 percent.

The downstream filter segment 250 comprises a cylindrical plug of cellulose acetate tow. The length of the downstream filter segment 250 is about 10 millimetres.

The downstream hollow tubular element 260 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The downstream hollow tubular element 260 defines an internal cavity that extends all the way from an upstream end of the downstream hollow tubular cooling element 220 to a downstream end of the downstream hollow tubular element 260. The internal cavity is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity. The downstream hollow tubular element 260 does not substantially contribute to the overall RTD of the aerosol-generating article 10. The length of the downstream hollow tubular element 260 is about 6 millimetres. The wall thickness of the downstream hollow tubular element 260 is about 1 millimetre.

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

Claims

1. An aerosol-generating article comprising: an aerosol-generating rod for producing an inhalable aerosol upon heating, the aerosol-generating rod comprising: a first aerosol-generating segment comprising a first aerosol-generating substrate; and a second aerosol-generating segment at a location upstream of the first aerosolgenerating segment and comprising a second aerosol-generating substrate, wherein the second aerosol-generating substrate has a higher aerosol former content than the first aerosol-generating substrate, and wherein the second aerosol-generating substrate has a higher density than the first aerosol-generating substrate.

2. An aerosol-generating article according to claim 1 , wherein the second aerosolgenerating substrate comprises an aerosol-generating film, the aerosol-generating film comprising a cellulosic based film forming agent, nicotine and glycerol, wherein the aerosolgenerating film has a glycerol content of at least 40 percent by weight.

3. An aerosol-generating article according to claim 2, wherein the aerosol-generating film is substantially tobacco free.

4. An aerosol-generating article according to any preceding claim, wherein the first aerosol-generating substrate comprises tobacco cut filler.

5. An aerosol-generating article according to any preceding claim, wherein the second aerosol-generating segment abuts the upstream end of the first aerosol-generating segment.

6. An aerosol-generating article according to any preceding claim, wherein the second aerosol-generating substrate comprises at least 50 percent by weight of glycerol, on a dry weight basis.

7. An aerosol-generating article according to any preceding claim, wherein the first aerosol-generating substrate is circumscribed by a first wrapper and wherein the second aerosol-generating substrate is circumscribed by a second wrapper, separate from the first wrapper.

8. An aerosol-generating article according to any preceding claim, wherein the aerosol former content of the second aerosol-generating substrate is at least 25 percent higher than the aerosol former content of the first aerosol-generating substrate, on a dry weight basis.

9. An aerosol-generating article according to any preceding claim, wherein the aerosol former content of the second aerosol-generating substrate is at least 1.5 times the aerosol former content of the first aerosol-generating substrate, on a dry weight basis.

10. An aerosol-generating article according to any preceding claim, wherein the ratio of the length of the first aerosol-generating segment to the length of the second aerosolgenerating segment is no more than 0.6.

11. An aerosol-generating article according to any preceding claim, wherein the bulk density of the first aerosol-generating substrate is less than 400 mg per cubic centimetre and the bulk density of the second aerosol-generating substrate is greater than 500 mg per cubic centimetre.

12. An aerosol-generating article according to any preceding claim, further comprising an upstream element provided upstream of the aerosol-generating rod and abutting an upstream end of the second aerosol-generating segment.

13. An aerosol-generating article according to any preceding claim, further comprising a downstream section provided downstream of the aerosol-generating rod and extending to the downstream end of the aerosol-generating article, wherein the downstream section comprises a hollow tubular cooling element.

14. An aerosol-generating article according to any preceding claim, wherein the aerosolgenerating article has a ventilation level of at least 40 percent.

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