Aerosol-Generating Article Comprising a Perforated Hollow Tubular Substrate Element

The present invention relates to an aerosol-generating article comprising a rod of aerosol-generating substrate that is adapted to produce an inhalable aerosol upon heating.

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

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

In general, it can be difficult to provide efficient heating of an aerosol-generating substrate throughout the whole rod of the substrate. The portions of the substrate closest to the heating element will inevitably be heated most effectively whilst the imperfect transfer of heat through the substrate will mean that portions of the substrate furthest from the heating element may not be effectively heated. The generation of aerosol from these portions of the substrate that are not effectively heated is therefore not optimal and in some cases, parts of the substrate may not reach a sufficiently high temperature during use for an aerosol to be generated at all. For example, where an external heating element is used to heat a rod of aerosol-generating substrate, as described above, the central portion of the rod of aerosol-generating substrate is unlikely to generate as much aerosol as the outer portions of the rod and in some cases, may not generate any aerosol. Overall, the generation of aerosol from the aerosol-generating rod is therefore likely to be inefficient, with potential waste of a portion of the aerosol-generating substrate.

In addition, aerosol is generally not immediately generated by the aerosol-generating substrate upon activation of a heating element. This is because there is a pre-heating time after activation of a heating element during which the aerosol-generating substrate is heated to a temperature required for aerosol generation. As such, there may be a relatively long duration between activation of a heating element and generation of a sensorially acceptable aerosol for inhalation by a user.

It would therefore be desirable to provide an aerosol-generating article having an aerosol-generating substrate that is adapted to provide more efficient aerosolisation of the aerosol-generating substrate and that reduces waste of the substrate materials, such as tobacco. It would also be desirable to provide such an aerosol-generating article that can achieve a relatively short pre-heating time so that a sensorially acceptable aerosol can be delivered to a user shortly after initiation of heating of the aerosol-generating substrate. It would also be desirable to provide such an aerosol-generating article that can provide optimised delivery of aerosol from the aerosol-generating substrate. It would be particularly desirable to provide such an aerosol-generating article with a relatively simple design so that it can be manufactured in a cost effective way and incorporated into existing product designs. It would be further desirable to provide such an article that can be readily adapted so that it can be heated in a variety of types of heating device, including inductive and resistive heating devices.

The present disclosure relates to an aerosol-generating article. The aerosol-generating article may comprise a rod of aerosol-generating substrate. The aerosol-generating article may comprise a downstream section provided downstream of the rod of aerosol-generating substrate. The rod of aerosol-generating substrate may comprise a hollow tubular substrate element. The hollow tubular substrate element may be formed of homogenised tobacco material. The hollow tubular substrate element may define a longitudinal cavity providing an unrestricted flow channel through the hollow tubular substrate element. The aerosol-generating substrate may comprise an outer wrapper circumscribing the hollow tubular substrate element. The outer wrapper may be arranged such that an empty space is defined between at least a part of the external surface of the hollow tubular substrate element and the outer wrapper. The hollow tubular substrate element may comprise a plurality of perforations. The plurality of perforations may provide fluid communication between the longitudinal cavity of the hollow tubular substrate element and the empty space between at least a part of the external surface of the hollow tubular substrate element and the outer wrapper.

According to the present invention there is provided an aerosol-generating article comprising: a rod of aerosol-generating substrate and a downstream section provided downstream of the rod of aerosol-generating substrate, wherein the rod of aerosol-generating substrate comprises: a hollow tubular substrate element formed of homogenised tobacco material and defining a longitudinal cavity providing an unrestricted flow channel through the hollow tubular substrate element; an outer wrapper circumscribing the hollow tubular substrate element and arranged such that an empty space is defined between at least a part of the external surface of the hollow tubular substrate element and the outer wrapper; wherein the hollow tubular substrate element comprises a plurality of perforations providing fluid communication between the longitudinal cavity of the hollow tubular substrate element and the empty space between at least a part of the external surface of the hollow tubular substrate element and the outer wrapper.

As used herein with reference to the present invention, the term “aerosol-generating article” is used to describe an article comprising an aerosol-generating substrate that is heated to generate an inhalable aerosol for delivery to a user.

As used herein with reference to the present invention, the term “aerosol-generating substrate” is used to describe a substrate comprising aerosol-generating material that is capable of releasing upon heating volatile compounds that can generate an aerosol.

As used herein with reference to the present invention, the term “aerosol” is used to describe a dispersion of solid particles, or liquid droplets, or a combination of solid particles and liquid droplets, in a gas. The aerosol may be visible or invisible. The aerosol may include vapours of substances that are ordinarily liquid or solid at room temperature as well as solid particles, or liquid droplets, or a combination of solid particles and liquid droplets.

As used herein with reference to the present invention, the term “rod” is used to denote a generally cylindrical element having a substantially circular, oval or elliptical cross-section.

Aerosol-generating articles according to the present invention have a downstream end through which, in use, an aerosol exits the aerosol-generating article for delivery to a user. The downstream end of the aerosol-generating article may also be referred to as the proximal end or mouth end of the aerosol-generating article. In use, a user draws directly or indirectly on the downstream end of the aerosol-generating article to inhale an aerosol generated by the aerosol-generating article.

Aerosol-generating articles according to the present invention have an upstream end. The upstream end is opposite the downstream end. The upstream end of the aerosol-generating article may also be referred to as the distal end of the aerosol-generating article.

Components of aerosol-generating articles according to the present invention may be described as being upstream or downstream of one another based on their relative positions between the upstream end of the aerosol-generating article and the downstream end of the aerosol-generating article.

As used herein with reference to the present invention, the term “longitudinal” refers to the direction between the upstream end and the opposed downstream end of the aerosol-generating article.

As used herein with reference to the present invention, the term “transverse” is used to describe the direction perpendicular to the longitudinal direction.

As used herein with reference to the present invention, the term “cross-section” is used to refer to the transverse cross-section of the aerosol-generating article or component thereof unless stated otherwise.

As used herein with reference to the present invention, the terms “hollow tubular element” and “hollow tubular substrate element” denote a generally elongate element defining a lumen or airflow passage along a longitudinal axis thereof. In particular, the term “tubular” is used 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 element may be an individual, discrete element of the aerosol-generating article which has a defined length and thickness.

As used herein with reference to the present invention, the term “homogenised tobacco material” encompasses any material formed by the agglomeration of tobacco particles. The homogenised tobacco material may be produced by casting, extrusion, paper making processes or any other suitable processes known in the art.

As used herein with reference to the present invention, the term “tobacco particles” describes particles of any plant member of the genusThe 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. Preferably, 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 present invention.

As described above, the present invention provides a hollow tubular substrate element and an outer wrapper circumscribing the hollow tubular substrate element and arranged such that an empty space is defined between at least part of the external surface of the hollow tubular substrate element and the outer wrapper. As such, the empty space is located externally of the hollow tubular substrate element.

The provision of a hollow tubular substrate element defining a longitudinal cavity, an empty space located externally of the hollow tubular substrate element, and a plurality of perforations through the wall of the hollow tubular substrate element providing fluid communication between the longitudinal cavity and the empty space may advantageously enable aerosol to be generated and released from both the internal surface and the external surface of the hollow tubular substrate element. Aerosol released from the external surface of the hollow tubular substrate element into the empty space may be drawn into the longitudinal cavity of the hollow tubular substrate element through the plurality of perforations as the consumer draws on the aerosol-generating article. This may advantageously increase the quantity of aerosol generated from the aerosol-generating substrate per puff. This may also enable a sensorially acceptable aerosol to be generated more quickly upon starting heating of the aerosol-generating substrate. As such, this may reduce a pre-heating time of the aerosol-generating article. In particular, where the aerosol-generating substrate is heated with external heating means, a sensorially acceptable aerosol may be generated more quickly due to the proximity of the external surface of the hollow tubular substrate element to the external heating means.

In addition, the provision of a plurality of perforations providing fluid communication between the longitudinal cavity and the empty space may advantageously increase a level of turbulence in the longitudinal cavity of the hollow tubular substrate element, for example, when the consumer draws on the aerosol-generating substrate. This may enhance mixing of air and aerosol-forming components that are released from the hollow tubular substrate element, thereby improving aerosol generation.

The provision of a substrate element in a tubular form may also advantageously enable the amount of tobacco material in the aerosol-generating substrate to be optimised so that aerosol can be efficiently generated from the aerosol-generating substrate upon heating. The tubular form also removes a central portion of homogenised tobacco material that would potentially not be heated as effectively as an outer portion, in particular, in an aerosol-generating device comprising external heating means. Overall, the amount of tobacco material can therefore be significantly reduced compared to conventional solid plugs of homogenised tobacco material and tobacco waste can be reduced. For example, it has been found that the amount of tobacco material used in the hollow tubular substrate element of aerosol-generating articles according to the present invention can be reduced by up to 40 percent compared to the amount of tobacco material used in the solid plug of substrate in a conventional aerosol-generating article, whilst retaining a similar delivery of aerosol to the consumer.

The amount of tobacco material provided in the substrate may be readily adapted through controlling the parameters of the hollow tubular substrate element, such as the density of a peripheral wall of the hollow tubular substrate element and the wall thickness. In this way, it may be possible to adapt the hollow tubular substrate element so that it matches the heating zone of an associated aerosol-generating device. The proportion of the aerosol-generating substrate that can be heated to the necessary temperature for aerosol generation may therefore be maximised so that the generation of aerosol from the aerosol-generating substrate may be optimised.

The hollow tubular substrate element has a relatively simple structure that may be produced in a straightforward and cost effective way, using existing apparatus. The hollow tubular substrate element can then be incorporated into aerosol-generating articles with other components, using known assembly methods and apparatus.

As described above, the hollow tubular substrate element is formed of homogenised tobacco material. Preferably, the hollow tubular substrate element is formed of one or more layers of homogenised tobacco material, such as cast leaf.

Preferably, the hollow tubular substrate element is formed of 2 or more overlapping layers of homogenised tobacco material, more preferably 3 or more overlapping layers of homogenised tobacco material.

The hollow tubular substrate element is preferably formed of up to 10 overlapping layers of homogenised tobacco material, more preferably up to 5 overlapping layers of homogenised tobacco material. For example, the hollow tubular substrate element may be formed of between about 2 and about 10 overlapping layers of homogenised tobacco material, or between about 3 and about 5 overlapping layers of homogenised tobacco material.

Preferably, the plurality of overlapping layers of homogenised tobacco material are directly overlying each other so that adjacent layers are in direct contact with each other, without intermediate layers.

The multi-layered arrangement of the layers may provide a relatively dense structure which has sufficient structural rigidity to provide the aerosol-generating substrate in an aerosol-generating article without the need for any additional support, such as carrier layers or internal support members within the longitudinal cavity.

Preferably the layers of homogenised tobacco material are in sheet form. As used herein with reference to the present invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.

The hollow tubular substrate element may have a length of at least about 5 millimetres, or at least about 7 millimetres, or at least about 10 millimetres.

The hollow tubular substrate element may have a length of up to about 30 millimetres, up to about 25 millimetres, or up to about 20 millimetres.

For example, the hollow tubular substrate element may have a length of between about 5 millimetres and about 30 millimetres, or between about 7 millimetres and about 25 millimetres, or between about 10 millimetres and about 20 millimetres.

Preferably, the hollow tubular substrate element has a length of about 12 millimetres.

As discussed above, the length of the hollow tubular substrate element may advantageously be matched to the longitudinal dimensions of the heating element in the corresponding aerosol-generating device which will be used to heat the aerosol-generating article. In this way, as much as possible of the aerosol-generating substrate can be heated during use, in order to optimise the amount of aerosol that can be generated and reduce the amount of tobacco waste.

Preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least about 0.1. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least about 0.15. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is at least about 0.2.

Preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is up to about 0.6. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is up to about 0.55. More preferably, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article is up to about 0.5.

For example, the ratio of the length of the hollow tubular substrate element to the overall length of the aerosol-generating article may be between about 0.1 and about 0.6, more preferably between about 0.15 and about 0.55, more preferably between about 0.2 and about 0.5.

Preferably, the hollow tubular substrate element has an external diameter less than an external diameter of the aerosol-generating article.

Preferably, the hollow tubular substrate element may have an external diameter of at least about 5 millimetres, or at least about 5.5 millimetres, or at least 6 millimetres.

Preferably, the hollow tubular substrate element may have an external diameter of up to about 9 millimetres, or up to about 8 millimetres, or up to about 7.5 millimetres.

For example, the hollow tubular substrate element may have an external diameter of between about 5 millimetres and about 9 millimetres, or between about 5.5 millimetres and 8 millimetres, or between about 6 millimetres and 7.5 millimetres.

Preferably, the external diameter of the hollow tubular substrate element is substantially constant along the length of the hollow tubular substrate. As an alternative, different portions of the hollow tubular substrate element may have different external diameters.

As used herein with reference to the present invention, the term “external diameter” refers to the maximum diameter of the aerosol-generating article or component thereof, in the transverse direction of the aerosol-generating article, at a position along the length of the aerosol-generating article or component thereof. Where a range or value for an external diameter of the aerosol-generating article or component thereof is described herein, the external diameter of the aerosol-generating article or component thereof along the entire length of the aerosol-generating article or component thereof may fall within the same range or have the same value. In other words, where a range or value for an external diameter of the aerosol-generating article or component thereof is described herein, the external diameter of the aerosol-generating article or component thereof at all positions along the length of the aerosol-generating article or component thereof may fall within the same range or have the same value.

The external diameter of the hollow tubular substrate element does not include the width of any other component of the aerosol-generating substrate located externally of the hollow tubular substrate element.

The hollow tubular substrate element has a peripheral wall which defines the longitudinal cavity. A wall thickness of the hollow tubular substrate element may be selected based on a desired amount of tobacco material within the hollow tubular substrate. A wall thickness of the hollow tubular substrate element may also be selected such that the hollow tubular substrate element has a sufficiently high rigidity that it can be self-supporting. A wall thickness of the hollow tubular substrate may also be selected such that the longitudinal cavity has a cross-sectional area that provides the hollow tubular substrate element with a desired resistance to draw (RTD).

The hollow tubular substrate element may have a wall thickness that is at least about 4 percent of an external diameter of the hollow tubular substrate element, or at least about 5 percent of an external diameter of the hollow tubular substrate element, or at least about 6 percent of an external diameter of the hollow tubular substrate element.