Aerosol-generating article and tubular element

Abstract

There is provided an aerosol-generating article (300) for use with an aerosol-generating device (400). The aerosol-generating article comprises a rod of aerosol-generating substrate (302); and a tubular element (100, 200) comprising: an inner tube (102, 202) comprising one or more first layers, the inner tube (102, 202) comprising a cellulosic material; an outer tube (104, 204) arranged around the inner tube, the outer tube comprising one or more second layers. The inner tube (102, 202) has a first compressive stiffness and the outer tube (104, 204) has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness. The outer tube (104, 204) has a wall thickness that is greater than a wall thickness of the inner tube (102, 202). There is also provided an aerosol-generating system (500). The aerosol-generating system (500) comprises: the aerosol-generating article (300) and an aerosol-generating device (400) configured to receive the aerosol-generating article (300). There is also provided a method of manufacturing an aerosol-generating article (300) comprising a tubular element (100, 200).

Description

[0001] AEROSOL-GENERATING ARTICLE AND TUBULAR ELEMENT

[0002] The present disclosure relates to a tubular element. The present disclosure also relates to an aerosol-generating article comprising the tubular element. The present disclosure also relates to an aerosol-generating system comprising an aerosol-generating device and the aerosol-generating article. The present disclosure also relates to a method of manufacturing an aerosol-generating article comprising a tubular element.

[0003] Aerosol-generating articles in which an aerosol-generating substrate, such as a tobaccocontaining substrate, is heated rather than combusted, are known in the art. Typically, in such heated smoking articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0004] A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosolgenerating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosol-generating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosol-generating substrate. Use of an aerosol-generating article in combination with an external heating system is also known. For example, WO 2020 / 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 aerosol-generating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosol-generating substrate have been proposed by WO 2015 / 176898.

[0005] Aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted present a number of challenges that were not encountered with conventional smoking articles. First of all, tobacco-containing substrates are typically heated to significantly lower temperatures compared with the temperatures reached by the combustion front in a conventional cigarette. This may have an impact on nicotine release from the tobacco-containing substrate and nicotine delivery to the consumer. At the same time, if the heating temperature is increased in an attempt to boost nicotine delivery, then the aerosol generated typically needs to be cooled to a greater extent and more rapidly before it reaches the consumer. However, technical solutions that were commonly used for cooling the mainstream smoke in conventional smoking articles,such as the provision of a high filtration efficiency segment at the mouth end of a cigarette, may have undesirable effects in an aerosol-generating article wherein a tobacco-containing substrate is heated rather than combusted, as they may reduce nicotine delivery. Accordingly, it would be desirable to provide aerosol-generating articles that can consistently ensure a satisfactory aerosol delivery to the consumer.

[0006] It would be desirable to provide an aerosol-generating article that can be produced using more sustainable materials, in order to minimise the environmental impact of used aerosolgenerating articles. However, the insertion force needed to insert aerosol-generating articles into a device cavity of an aerosol-generating device may be high and there may be variability in the insertion force required to insert aerosol-generating articles into the device cavity.

[0007] It would be desirable to provide an aerosol-generating article that is easy to use and has an improved practicality. In particular, it would be desirable to provide an aerosol-generating article that can be easily inserted into a device cavity of the aerosol-generating device, and that at the same time can be retained securely within the device cavity during use. It would also be desirable to reduce the variability of force required to the insert the aerosol-generating article into the device cavity, for example between aerosol-generating articles used with the aerosolgenerating device.

[0008] According to a first aspect of the present disclosure there is provided a tubular element. The tubular element may comprise an inner tube comprising one or more first layers. The inner tube may comprise a cellulosic material. An outer tube may be arranged around the inner tube. The outer tube may comprise one or more second layers. The inner tube may have a first compressive stiffness. The outer tube may have a second compressive stiffness. The second compressive stiffness may be less than the first compressive stiffness. The outer tube may have a wall thickness that is greater than a wall thickness of the inner tube.

[0009] According to a first aspect of the present invention there is provided a tubular element. The tubular element comprises an inner tube comprising one or more first layers. The inner tube comprises a cellulosic material. An outer tube is arranged around the inner tube. The outer tube comprises one or more second layers. The inner tube has a first compressive stiffness. The outer tube has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness.

[0010] According to a particularly preferred embodiment of a first aspect of the present invention there is provided a tubular element. The tubular element comprises an inner tube comprising one or more first layers. The inner tube comprises a cellulosic material. An outer tube is arranged around the inner tube. The outer tube comprises one or more second layers. The inner tube has a first compressive stiffness. The outer tube has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness. The outer tube has a wall thickness that is greater than a wall thickness of the inner tube.According to a second aspect of the present disclosure there is provided an aerosolgenerating article for use with an aerosol-generating device. The aerosol-generating article may comprise a rod of aerosol-generating substrate. The aerosol-generating article may comprise a tubular element. The tubular element may comprise an inner tube comprising one or more first layers. The inner tube may comprise a cellulosic material. An outer tube may be arranged around the inner tube. The outer tube may comprise one or more second layers. The inner tube may have a first compressive stiffness. The outer tube may have a second compressive stiffness. The second compressive stiffness may be less than the first compressive stiffness. The outer tube may have a wall thickness that is greater than a wall thickness of the inner tube.

[0011] According to a second aspect of the present invention there is provided an aerosolgenerating article for use with an aerosol-generating device. The aerosol-generating article comprises a rod of aerosol-generating substrate. The aerosol-generating article comprises a tubular element. The tubular element comprises an inner tube comprising one or more first layers. The inner tube comprises a cellulosic material. An outer tube is arranged around the inner tube. The outer tube comprises one or more second layers. The inner tube has a first compressive stiffness. The outer tube has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness.

[0012] According to a particularly preferred embodiment of a second aspect of the present invention there is provided an aerosol-generating article for use with an aerosol-generating device. The aerosol-generating article comprises a rod of aerosol-generating substrate. The aerosol-generating article comprises a tubular element. The tubular element comprises an inner tube comprising one or more first layers. The inner tube comprises a cellulosic material. An outer tube is arranged around the inner tube. The outer tube comprises one or more second layers. The inner tube has a first compressive stiffness. The outer tube has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness. The outer tube has a wall thickness that is greater than a wall thickness of the inner tube.

[0013] Advantageously, providing the tubular element comprising the inner tube having a first compressive stiffness and the outer tube having a second compressive stiffness that is less than the first compressive stiffness may reduce the force required to insert the tubular element into a device cavity of an aerosol-generating device. At the same time, advantageously, sufficiently strong retention of the tubular element in a device cavity may be achieved. Advantageously, variations in the force required to insert the tubular element into the device cavity resulting from any variability in an outer diameter of the tubular element may also be reduced.

[0014] Advantageously, the overall structure of the outer tube during insertion of the tubular element into the device cavity may remain elastic when inserted in the heating device because the inner tube may provide a buffering structure that may reduce the deformation experienced by the outer tube.Advantageously, providing the tubular element comprising the inner tube comprising a cellulosic material and having a first compressive stiffness, and the outer tube having a second compressive stiffness that is less than the first compressive stiffness may facilitate the provision of a tubular element comprising biodegradable materials such as paper or cardboard.

[0015] Advantageously, providing the inner tube having a first compressive stiffness that is greater than the second compressive stiffness may provide improved control of the internal dimensions of the tubular element and may improve the structural integrity of the tubular element and prevent any migration of layers of the tubular element into a lumen of the tubular element defining an internal air path through the tubular element. Advantageously, providing the inner tube having a first compressive stiffness that is greater than the second compressive stiffness may improve control over the resistance to draw through the tubular element when the tubular element is inserted into a device cavity.

[0016] Advantageously, the tubular element comprising the inner tube and the outer tube may be simple to manufacture.

[0017] Advantageously, the tubular element comprising the inner tube and the outer tube may help to retain components provided in adjacent elements in an aerosol-generating article comprising the tubular element, such as a susceptor received in the rod of aerosol-generating substrate of the aerosol-generating article.

[0018] As used herein, the term “compressive stiffness” refers to the stiffness of a component of the tubular element under compression in a direction perpendicular to a longitudinal axis of the tubular element.

[0019] When comparing compressive stiffness of components, it will be appreciated that the compressive stiffness may be calculated by measuring the force required to deform the component in a direction perpendicular to a longitudinal axis of the tubular element by a given displacement of the component’s outer surface. For example, the compressive stiffness of components may be measured by compressing the component at a given point by a chosen displacement, such as 1 millimetre, and then measuring the applied force. The chosen displacement and applied force may be selected such that the measurement of the compressive stiffness of the components remains in the elastic region of deformation for the components. Alternatively, the compressive stiffness may be equally calculated by measuring the displacement of a component’s outer surface in a direction perpendicular to a longitudinal axis of the tubular element following the application of a known force. Reference to the displacement of the outer surface of the component perpendicular to a longitudinal axis of the tubular element where the component is in the shape of a tube may refer to a reduction in the outer radius of the component and the applied force may be in a radial direction of the component.

[0020] For example, compressing the outer tube in a direction perpendicular to a longitudinal axis of the tubular element by a given displacement of the outer tube’s outer surface, such as 1millimetre, may require a lower applied force than compressing the inner tube in a direction perpendicular to a longitudinal axis of the tubular element by the same given displacement of the inner tube’s outer surface. Similarly, compressing the outer tube in a direction perpendicular to a longitudinal axis of the tubular element with the application of a given applied force may result in a greater displacement of its surface in a direction perpendicular to a longitudinal axis of the tubular element compared to compressing the inner tube in a direction perpendicular to a longitudinal axis of the tubular element with the application of the same given applied force. In other words, the outer tube may be referred to as “softer” than the inner tube or the inner tube may be referred to as “harder” than the outer tube.

[0021] As used herein, the term layer" may denote an element having a width and length substantially greater than the thickness thereof.

[0022] As used herein, the term " tubular element" is used to denote an element defining a lumen or airflow passage along a longitudinal axis thereof.

[0023] As used herein, the term ‘aerosol-generating substrate’ denotes a substrate capable of releasing volatile compounds upon heating, which can condense to form an aerosol.

[0024] As used herein, the term “aerosol” denotes 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.

[0025] As used herein, the term “aerosol-generating article” denotes an article comprising an aerosol-generating substrate that is capable of releasing volatile compounds that can form an aerosol. An aerosol-generating article may be disposable.

[0026] As used herein, the term “aerosol-generating device” denotes a device that interacts with an aerosol-generating substrate to generate an aerosol. An aerosol-generating device may interact with an aerosol-generating article comprising an aerosol-generating substrate. In some examples, the aerosol-generating device heats the aerosol-generating substrate to facilitate release of volatile compounds from the substrate.

[0027] As used herein, the term "aerosol-generating system" denotes a combination of an aerosol-generating device and an aerosol-generating substrate. When the aerosol-generating substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of the aerosol-generating device and the aerosol-generating article. In the aerosolgenerating system, the aerosol-generating substrate and the aerosol-generating device cooperate to generate an aerosol.

[0028] As used herein, the terms ’upstream’, ‘downstream’, proximal’ and ‘distal’ are used to describe the relative positions of elements, or portions of elements, of aerosol-generating articles, aerosol-generating devices and aerosol-generating systems according to the disclosure.Aerosol-generating articles as described herein comprise a proximal end through which, in use, an aerosol exits the aerosol-generating article. The proximal end may also be referred to as the mouth end. In use, a user draws on the proximal end or mouth end of the aerosol-generating article in order to inhale an aerosol generated by the aerosol-generating article. The aerosolgenerating article comprises a distal end opposite the proximal end or mouth end. The proximal end or mouth end of the aerosol-generating article may also be referred to as the downstream end. The distal end of the aerosol-generating article may also be referred to as the upstream end. Components, or portions of components, of the aerosol-generating article may be described as being upstream or downstream of one another based on their relative positions between the proximal or downstream end and the distal or upstream end of the aerosol-generating article.

[0029] As used herein, the term ‘longitudinal’ is used to describe the direction between the downstream end or proximal end and the opposed upstream end or distal end of tubular elements, aerosol-generating articles, aerosol-generating devices and aerosol-generating systems according to the invention.

[0030] As used herein, the term ‘length’ is used to describe the maximum dimension of elements, or portions of elements, of aerosol-generating articles, aerosol-generating devices and aerosolgenerating systems according to the disclosure in the longitudinal direction.

[0031] As used herein, the term ‘transverse’ is used to describe the direction perpendicular to the longitudinal direction.

[0032] As used herein, the term ‘width’ is used to describe the maximum transverse dimension of elements, or portions of elements, of aerosol-generating articles, aerosol-generating devices and aerosol-generating systems according to the disclosure. For the avoidance of doubt, as used herein the term ‘diameter’ may also be used to refer to the ‘width’ of elements, or portions of elements, of aerosol-generating articles, aerosol-generating devices and aerosol-generating systems according to the disclosure, which have a circular transverse cross-section.

[0033] Preferably, a hardness of the outer tube is less than a hardness of the inner tube.

[0034] The tubular element may have a hardness of less than or equal to 95 percent, less than or equal to 90 percent, or less than or equal to 85 percent.

[0035] The tubular element may have a hardness of greater than or equal to 75 percent, or greater than or equal to 80 percent.

[0036] For example, the tubular element may have a hardness of between 75 percent and 95 percent, or preferably the tubular element may have a hardness of between 80 percent and 90 percent.

[0037] As used herein, the term “hardness” may refer to Borgwaldt hardness. The hardness may be measured using a Borgwaldt-kc densimeter DD 60 A. Preferably, the hardness is measured using the application of a pressure to a component of between 2 and 5 kilopascals, such as 2 kilopascals. In particular, the hardness may be measured as follows: an initial diameter of thecomponent may be measured, a controlled force may then be applied using the pressure to compress the component, the final diameter of the compressed component may be measured, and the hardness may then be calculated using a percentage change of the initial diameter to the final diameter. Specifically, the hardness may be 100% minus the percentage change of the initial diameter to the final diameter. The percentage change of the initial diameter to the final diameter may be the change in diameter divided by the initial diameter, converted into a percentage.

[0038] Without wishing to be bound by theory, it will be appreciated that where the hardness of the outer tube is less than a hardness of the inner tube, the hardness of the tubular element overall may be substantially determined only by the compression of the outer tube.

[0039] Preferably, the outer tube has a hardness of less than or equal to 60 percent, less than or equal to 55 percent, or less than or equal to 50 percent.

[0040] Preferably, an outer diameter of the outer tube reduces by greater than or equal to 40 percent, greater than or equal to 45 percent, or greater than or equal to 50 percent during the application of between 2 kilopascals and 5 kilopascals of pressure to an outermost surface of the tubular element.

[0041] Preferably, the inner tube has a hardness of greater than or equal to 90 percent, greater than or equal to 95 percent, or substantially equal to 100 percent.

[0042] Preferably, an outer diameter of the inner tube does not substantially reduce, or an outer diameter of the inner tube reduces by less than or equal to 10 percent, or less than or equal to 5 percent during the application of between 2 kilopascals and 5 kilopascals of pressure to an outermost surface of the tubular element.

[0043] Advantageously, providing the tubular element having the hardness described herein may reduce the force required to insert the tubular element into a device cavity of an aerosolgenerating device. At the same time, advantageously, sufficiently strong retention of the tubular element in a device cavity may be achieved. Without wishing to be bound by theory, providing the outer tube having a second compressive stiffness that is less than the first compressive stiffness of the inner tube as described herein may reduce the hardness of the tubular element.

[0044] The inner tube comprises a cellulosic material. The one or more first layers may comprise the cellulosic material. Preferably, the cellulosic material is selected from one or both of cardboard and paper. For example, the one or more first layers of the inner tube may comprise one or more layers of paper and one or more first layers of cardboard.

[0045] The grammage of the one or more first layers may be greater than or equal to 40 grams per square metre, greater than or equal to 100 grams per square metre, or greater than or equal to 170 grams per square metre.

[0046] The grammage of the one or more first layers may be less than or equal to 250 grams per square metre, less than or equal to 200 grams per square metre, less than or equal to 150 grams per square metre, less than or equal to 120 grams per square metre.For example, the grammage of the one or more first layers may be between 40 grams per square metre and 150 grams per square metre, or the grammage of the one or more first layers may be between 100 grams per square metre and 200 per square metre.

[0047] Preferably, an inner surface of the inner tube defines an innermost surface of the tubular element. Preferably, an internal diameter of the tubular element is greater than or equal to 3 millimetres.

[0048] Advantageously, providing the inner surface of the inner tube defining an innermost surface of the tubular element may allow the inner tube to define the dimensions of a lumen of the tubular element to control the resistance to draw through the tubular element.

[0049] The inner tube may have a wall thickness of greater than or equal to 0.1 millimetres, preferably greater than or equal to 0.15 millimetres, or more preferably greater than or equal to 0.2 millimetres.

[0050] The inner tube may have a wall thickness of less than or equal to 1 millimetre, preferably less than or equal to 0.4 millimetres or more preferably less than or equal to 0.3 millimetres.

[0051] For example, the inner tube may have a wall thickness of between 0.2 millimetres and 0.3 millimetres.

[0052] The outer tube may comprise an outer tube material. The one or more second layers may comprise the outer tube material.

[0053] The outer tube material may comprise a non-woven material. Preferably, the non-woven material is one or more of BioLace, lyocell or viscose. The outer tube material may comprise a binder. Preferably, the BioLace is a wetlaid non-woven material, for example prepared using a hydroentanglement process. Preferably, the BioLace comprises one or both of cellulose and regenerated cellulose. The outer tube material may be a non-paper material.

[0054] The outer tube material may comprise a foam. The foam may be an open cell foam or a closed cell foam.

[0055] Preferably, the cellulosic material and the outer tube material are different.

[0056] The cellulosic material may have a first Young’s modulus in a direction perpendicular to a longitudinal axis of the tubular element.

[0057] The first Young's modulus may be greater than or equal to 10 megapascals, greater than or equal to 50 megapascals, greater than or equal to 100 megapascals, greater than or equal to 250 megapascals, greater than or equal to 500 megapascals, or greater than or equal to 1 gigapascal.

[0058] The first Young's modulus may be less than or equal to 20 gigapascals, less than or equal to 10 gigapascals, or less than or equal to 5 gigapascals.

[0059] For example, the first Young’s modulus may be between 10 megapascals and 5 gigapascals.The outer tube material may have a second Young’s modulus in a direction perpendicular to a longitudinal axis of the tubular element.

[0060] Preferably, the second Young's modulus is less than the first Young's modulus.

[0061] The second Young's modulus may be greater than or equal to 1 kilopascal, greater than or equal to 2 kilopascals, greater than or equal to 10 kilopascals, greater than or equal to 50 kilopascals, greater than or equal to 250 kilopascals, or greater than or equal to 1 megapascal.

[0062] The second Young's modulus may be less than or equal to 2 megapascals, less than or equal to 1 megapascal, less than or equal to 500 kilopascals, less than or equal to 100 kilopascals, less than or equal to 50 kilopascals, less than or equal to 10 kilopascals or less than or equal to 5 kilopascals.

[0063] For example, the second Young's modulus may be between 1 kilopascal and 1 megapascal, or between 2 kilopascals and 5 kilopascals, such as about 4 kilopascals.

[0064] Preferably, the outer tube is elastically compressible when the compressive strain is less than or equal to 50 percent.

[0065] The outer tube may have an internal diameter that is substantially the same as an external diameter of the inner tube.

[0066] The outer tube may have a wall thickness of greater than or equal to 0.2 millimetres, preferably greater than or equal to 0.5 millimetres, or more preferably greater than or equal to 0.8 millimetres.

[0067] The outer tube may have a wall thickness of less than or equal to 2 millimetres, preferably less than or equal to 1.2 millimetre or more preferably less than or equal to 1 millimetre.

[0068] For example, the outer tube may have a wall thickness of between 0.2 millimetres and 2 millimetres, preferably the outer tube has a wall thickness of between 0.5 millimetres and 1 millimetre.

[0069] Preferably, the outer tube has a wall thickness that is greater than a wall thickness of the inner tube. It will be appreciated that the wall thicknesses of each of the outer tube and the inner tube may be measured in the absence of an applied force to the tubular element, such as in particular the absence of an applied force in a direction perpendicular to a longitudinal axis of the tubular element. For example, the wall thicknesses of each of the outer tube and the inner tube may be measured before the tubular element is inserted into a device cavity of an aerosolgenerating device.

[0070] The outer tube may be attached to the inner tube by an adhesive.

[0071] Preferably, an outer surface of the outer tube defines an outermost surface of the tubular element.

[0072] Advantageously, providing the outer surface of the outer tube defining an outermost surface of the tubular element may allow the outer tube to be freely compressed and thendecompressed without being constrained by a further element overlying the outer surface of the outer tube.

[0073] The tubular element may further comprise a wrapper. The wrapper may be a plug wrap. The wrapper may comprise one or more wrapper layers comprising a wrapping material. Preferably, the wrapping material is paper.

[0074] Preferably, the wrapper is arranged around the outer tube. Preferably, an outer surface of the wrapper defines an outermost surface of the tubular element. The wrapper may be attached to the outer tube by an adhesive.

[0075] Advantageously, providing the wrapper arranged around the outer tube may reduce or prevent damage to the outer tube during handling of the tubular element and may protect the outer tube during the manufacturing of the tubular element. Advantageously, providing the wrapper arranged around the outer tube may prevent transfer of the outer tube material to components of the manufacturing machines during manufacturing of the tubular element.

[0076] A grammage of the wrapper may be greater than or equal to 15 grams per square metre, or greater than or equal to 25 grams per square metre.

[0077] A grammage of the wrapper may be less than or equal to 78 grams per square metre, or less than or equal to 30 grams per square metre.

[0078] For example, a grammage of the wrapper may be between 15 grams per square metre and 30 grams per square metre, or between 25 grams per square metre and 78 grams per square metre.

[0079] Preferably, a grammage of the wrapper is less than the grammage of the outer tube. The tubular element may comprise an intermediate tube arranged between the inner tube and the outer tube. The intermediate tube may comprise one or more third layers. Preferably, the intermediate tube comprises a material that is different to the outer tube material. Preferably, the one or more third layers comprises a material that is different to the one or more second layers. Preferably, the intermediate tube comprises paper. In particular, the one or more third layers may comprise paper.

[0080] Preferably, the intermediate tube has a third compressive stiffness. Preferably, the second compressive stiffness is less than the third compressive stiffness. A hardness of the intermediate tube may be greater than the hardness of the outer tube.

[0081] Advantageously, providing an intermediate tube arranged between the inner tube and the outer tube may provide support for the one or more second layers during manufacture of the tubular element. Advantageously, providing an intermediate tube arranged between the inner tube and the outer tube may facilitate attachment of the one or more first layers to the one or more second layers during manufacture of the tubular element.

[0082] The intermediate tube may be attached to one or both of the inner tube and the outer tube by an adhesive.An external diameter of the tubular element may be less than or equal to 8 millimetres, less than or equal to 7.5 millimetres, less than or equal to 7.2 millimetres, or less than or equal to 7 millimetres.

[0083] An external diameter of the tubular element may be greater than or equal to 5.5 millimetres, greater than or equal to 6 millimetres, or greater than or equal to 6.5 millimetres.

[0084] For example, an external diameter of the tubular element is between 5.5 millimetres and 8 millimetres.

[0085] A length of the tubular element may be greater than or equal to 5 millimetres, greater than or equal to 9 millimetres, greater than or equal to 10 millimetres, greater than or equal to 15 millimetres, or greater than or equal to 20 millimetres.

[0086] A length of the tubular element may be less than or equal to 45 millimetres, less than or equal to 35 millimetres, less than or equal to 25 millimetres, or less than or equal to 21 millimetres.

[0087] For example, a length of the tubular element may be between 9 millimetres and 21 millimetres.

[0088] A length of the inner tube may be equal to the length of the tubular element. A length of the outer tube may be equal to the length of the tubular element.

[0089] The tubular element may comprise ventilation. The tubular element may comprise ventilation holes.

[0090] Preferably, the tubular element is downstream of the rod of aerosol-generating substrate in the aerosol-generating article. Preferably, the tubular element abuts a downstream end of the rod of aerosol-generating substrate.

[0091] A susceptor element may be embedded in the rod of aerosol-generating substrate. The susceptor element may be a planar susceptor element.

[0092] Preferably, an internal diameter of the tubular element is less than a width of the susceptor element. In particular, an internal diameter of the inner tube may be less than a width of the susceptor element.

[0093] Advantageously, providing the tubular element may assist in retaining the susceptor element in the rod of aerosol-generating substrate.

[0094] As used herein, the term “susceptor” denotes a material that is capable of being heated when penetrated by a varying magnetic field. The susceptor may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosolgenerating substrate. For example, the susceptor may comprise a metal or carbon.

[0095] The susceptor 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 may be, or comprise, aluminium. The susceptor may be formed from 400 series stainless steels, for example grade 410, or grade 420, or grade 430 stainless steel.The aerosol-generating article may comprise a mouthpiece element downstream of the tubular element. Preferably, the mouthpiece element abuts a downstream end of the tubular element. The mouthpiece element may be a mouthpiece filter. The mouthpiece element may comprise cellulose acetate. The mouthpiece element may define a proximal or downstream end of the aerosol-generating article.

[0096] The aerosol-generating article may comprise an upstream element. The upstream element may define a distal or an upstream end of the aerosol-generating article. Preferably, the upstream element is upstream of the rod of aerosol-generating substrate. Preferably, the upstream element abuts an upstream end of the rod of aerosol-generating substrate. The upstream element may be a cellulose acetate plug. The upstream element may be at a distal end of the aerosol-generating article.

[0097] The aerosol-generating article may comprise an outer wrapper. The outer wrapper may circumscribe one or more of the tubular element, the mouthpiece element, the upstream element and the rod of aerosol-generating substate. Preferably, the outer wrapper circumscribes the tubular element and the rod of aerosol-generating substrate. The outer wrapper may circumscribe only part of the tubular element. The outer wrapper may circumscribe an entire length of the tubular element. The outer wrapper may extend from a downstream end of the aerosol-generating article.

[0098] The outer wrapper may comprise tipping paper. A cigarette paper may be provided underlying the outer wrapper. The cigarette paper may be provided between the tubular element and the outer wrapper. The cigarette paper may circumscribe an entire length of the tubular element. The cigarette paper may circumscribe an entire length of the aerosol-generating article.

[0099] The aerosol-generating article may comprise a plurality of the tubular elements, each according to the disclosure provided herein. For example, a first tubular element and a second tubular element may be provided. The first tubular element and the second tubular element may be arranged downstream of the rod of aerosol-generating substrate in the aerosol-generating article. The second tubular element may be arranged downstream of the first tubular element. The second tubular element may abut the first tubular element. An internal diameter of the second tubular element may be larger than an internal diameter of the first tubular element. A wall thickness of the second tubular element may be less than a wall thickness of the first tubular element. The cigarette paper may circumscribe the first tubular element and the second tubular element. The outer wrapper may circumscribe the second tubular element. Preferably, the outer wrapper does not circumscribe the first tubular element.

[0100] An external diameter of the aerosol-generating article may be less than or equal to 8 millimetres, less than or equal to 7.5 millimetres, or less than or equal to 7.2 millimetres.

[0101] An external diameter of the aerosol-generating article may be greater than or equal to 5.5 millimetres, greater than or equal to 6 millimetres, or greater than or equal to 6.5 millimetres.For example, an external diameter of the aerosol-generating article may be between 5.5 millimetres and 8 millimetres.

[0102] A length of the aerosol-generating article may be greater than or equal to 40 millimetres, greater than or equal to 60 millimetres, greater than or equal to 80 millimetres, or greater than or equal to 100 millimetres.

[0103] A length of the aerosol-generating article may be less than or equal to 150 millimetres, less than or equal to 130 millimetres, less than or equal to 110 millimetres, less than or equal to 90 millimetres, less than or equal to 70 millimetres, or less than or equal to 50 millimetres.

[0104] For example, a length of the aerosol-generating article may be between 40 millimetres and 150 millimetres.

[0105] The aerosol-generating substrate may be a solid aerosol-generating substrate.

[0106] The aerosol-generating substrate may comprise tobacco material.

[0107] As used herein, the term “tobacco material” is used to describe any material comprising tobacco, including, but not limited to, tobacco leaf, tobacco rib, tobacco stem, tobacco stalk, tobacco dust, expanded tobacco, reconstituted tobacco material and homogenised tobacco material.

[0108] The aerosol-generating substrate in the rod of aerosol-generating substrate the aerosolgenerating substrate may comprise homogenised tobacco material.

[0109] As used herein, the term ‘homogenised tobacco material’ denotes a material formed by agglomerating particulate tobacco.

[0110] The aerosol-generating substrate may comprise a plurality of shreds of tobacco material, such as tobacco cut filler or shreds of homogenised tobacco material.

[0111] Shreds of homogenised tobacco material may be formed from a sheet of homogenised tobacco material, for example, by cutting or shredding. Shreds of homogenised tobacco material may be formed by other methods, for example, by extrusion.

[0112] The aerosol-generating substrate preferably comprises an aerosol former. The aerosol former may be any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol. The aerosol former may be facilitating that the aerosol is substantially resistant to thermal degradation at temperatures typically applied during use of the aerosol-generating article. Suitable aerosol formers are for example: polyhydric alcohols such as, for example, triethylene glycol, 1,3-butanediol, propylene glycol and glycerine; esters of polyhydric alcohols such as, for example, glycerol mono-, di- or triacetate; aliphatic esters of mono-, di- or polycarboxylic acids such as, for example, dimethyl dodecanedioate and dimethyl tetradecanedioate; and combinations thereof.

[0113] The aerosol former may comprise one or more of glycerine and propylene glycol. The aerosol former may consist of glycerine or propylene glycol or of a combination of glycerine and propylene glycol.The aerosol-generating substrate may comprise greater than or equal to 5 percent, greater than or equal to 10 percent, or greater than or equal to 12 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate.

[0114] The aerosol-generating substrate may comprise less than or equal to 30 percent, less than or equal to 25 percent, or less than or equal to 20 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate.

[0115] The aerosol-generating substrate may comprise between 5 percent and 30 percent, between 5 percent and 25 percent, or between 5 percent and 20 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate.

[0116] The aerosol-generating substrate may comprise one or more carboxylic acids.

[0117] The aerosol-generating substrate may comprise nicotine.

[0118] As used herein with reference to the invention, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt.

[0119] According to a third aspect of the present disclosure there is provided an aerosolgenerating system. The aerosol-generating system may comprise an aerosol-generating article according to the second aspect of the present disclosure. The aerosol-generating system may comprise an aerosol-generating device configured to receive the aerosol-generating article. The aerosol-generating device may be configured to heat the aerosol-generating article when the aerosol-generating article is received in the aerosol-generating device.

[0120] According to a third aspect of the present invention there is provided an aerosolgenerating system. The aerosol-generating system comprises an aerosol-generating article according to the second aspect of the present disclosure. The aerosol-generating system comprises an aerosol-generating device configured to receive the aerosol-generating article. The aerosol-generating device is configured to heat the aerosol-generating article when the aerosolgenerating article is received in the aerosol-generating device.

[0121] Preferably, the aerosol-generating device comprises a device cavity configured to receive the aerosol-generating article. Preferably, the device cavity is configured to receive the tubular element of the aerosol-generating article.

[0122] Advantageously, providing an aerosol-generating system comprising the aerosolgenerating article comprising the tubular element may reduce the force required to insert the aerosol-generating article into the device cavity. At the same time, advantageously, sufficiently strong retention of the aerosol-generating article in the device cavity may be achieved. Advantageously, variations in the force required to insert the aerosol-generating article into the device cavity resulting from any variability in an outer diameter of the tubular element may also be reduced.

[0123] Preferably, the aerosol-generating device comprises one or more protrusions extending into the device cavity.Preferably, the one or more protrusions are arranged to compress at least part of the outer tube of the tubular element when the aerosol-generating article is received in the aerosolgenerating device.

[0124] Advantageously, the one or more protrusions extending into the device cavity may assist in retaining the aerosol-generating article in the device cavity. In particular, when used in combination with the tubular element, the one or more protrusions may provide strong retention of the aerosol-generating article in the device cavity.

[0125] The one or more protrusions may be arranged to compress the outer tube of the tubular element by a compressive strain of less than or equal to 50 percent when the aerosol-generating article is received in the aerosol-generating device.

[0126] Alternatively, the one or more protrusions may be arranged to compress the outer tube of the tubular element by a compressive strain of greater than or equal to 50 percent when the aerosol-generating article is received in the aerosol-generating device.

[0127] The one or more protrusions may be arranged to deform the intermediate tube when the aerosol-generating article is received in the aerosol-generating device.

[0128] The one or more protrusions may be arranged to deform the inner tube when the aerosolgenerating article is received in the aerosol-generating device.

[0129] The aerosol-generating system may comprise a heater element configured to heat the aerosol-generating article.

[0130] The aerosol-generating device may comprise the heater element.

[0131] The aerosol-generating article may comprise the heater element.

[0132] The heater element may be a susceptor element. Preferably, the aerosol-generating device comprises an inductor coil configured to heat the susceptor element. Preferably, the susceptor element is embedded in the rod of aerosol-generating substrate of the aerosolgenerating article and the aerosol-generating generate device comprises the inductor coil.

[0133] The inductor coil may at least partly circumscribe the device cavity. The inductor coil may be arranged to coaxially circumscribe the device cavity.

[0134] The heater element may be a resistive heater element.

[0135] The aerosol-generating device may further comprise a controller.

[0136] The aerosol-generating device may further comprise a power supply. The power supply may be a DC power supply. The power supply may a battery. 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.

[0137] According to a fourth aspect of the present disclosure there is provided a method of manufacturing an aerosol-generating article comprising a tubular element. The method may comprise providing one or more first layers comprising a cellulosic material. The method may comprise providing one or more second layers. The method may comprise overlying the one ormore second layers on the one or more first layers. The method may comprise forming a tubular element comprising an inner tube and an outer tube around the inner tube. The inner tube may comprise the one or more first layers. The outer tube may comprise the one or more second layers. The inner tube may have a first compressive stiffness. The outer tube may have a second compressive stiffness. The second compressive stiffness may be less than the first compressive stiffness. The outer tube may have a wall thickness that is greater than a wall thickness of the inner tube. The method may comprise providing a rod of aerosol-generating substrate.

[0138] According to a fourth aspect of the present invention there is provided a method of manufacturing an aerosol-generating article comprising a tubular element. The method comprises providing one or more first layers comprising a cellulosic material. The method comprises providing one or more second layers. The method comprises overlying the one or more second layers on the one or more first layers. The method comprises forming a tubular element comprising an inner tube and an outer tube around the inner tube. The inner tube comprises the one or more first layers. The outer tube comprises the one or more second layers. The inner tube has a first compressive stiffness. The outer tube has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness. The method comprises providing a rod of aerosol-generating substrate.

[0139] According to a particularly preferred embodiment of a fourth aspect of the present invention there is provided a method of manufacturing an aerosol-generating article comprising a tubular element. The method comprises providing one or more first layers comprising a cellulosic material. The method comprises providing one or more second layers. The method comprises overlying the one or more second layers on the one or more first layers. The method comprises forming a tubular element comprising an inner tube and an outer tube around the inner tube. The inner tube comprises the one or more first layers. The outer tube comprises the one or more second layers. The inner tube has a first compressive stiffness. The outer tube has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness. The outer tube has a wall thickness that is greater than a wall thickness of the inner tube. The method comprises providing a rod of aerosol-generating substrate.

[0140] The tubular element may comprise any of the features described herein, including in relation to any other aspect of the present disclosure.

[0141] The aerosol-generating article may comprise any of the features described herein, including in relation to any other aspect of the present disclosure.

[0142] The method may comprise forming a tube comprising the one or more second layers around the one or more first layers, and cutting the tube to form the tubular element comprising the inner tube and the outer tube around the inner tube.

[0143] The method may comprise combining the tubular element and the rod of aerosolgenerating substrate. The method may comprise aligning the tubular element with the rod ofaerosol-generating substrate along a longitudinal axis. The method may comprise wrapping the tubular element and the rod of aerosol-generating substrate in an outer wrapper.

[0144] The method may comprise forming the inner tube from the one or more first layers and wrapping the inner tube in the one or more second layers to form the outer tube around the inner tube.

[0145] Forming the inner tube may comprise forming the one or more first layers by winding a plurality of substantially continuous first strips. Preferably, the plurality of substantially continuous first strips comprise the cellulosic material.

[0146] Preferably, the plurality of substantially continuous first strips are wound around a cylindrical mandrel.

[0147] Preferably, the plurality of substantially continuous first strips are wound in a spiral. Preferably, the pitch of the spiral is equal to a width of each of the plurality of substantially continuous first strips.

[0148] Forming the outer tube may comprise forming the one or more second layers by winding a plurality of substantially continuous second strips around the inner tube. The one or more second layers may comprise the outer tube material. Preferably, the plurality of substantially continuous second strips comprise the outer tube material.

[0149] Preferably, the plurality of substantially continuous second strips are wound in a spiral. Preferably, the pitch of the spiral is equal to a width of each of the plurality of substantially continuous second strips.

[0150] An inner surface of each of the plurality of substantially continuous first strips other than the innermost substantially continuous first strip may be coated with an adhesive.

[0151] An inner surface of each of the plurality of substantially continuous second strips may be coated with an adhesive.

[0152] The method may comprise providing one or more third layers overlying the one or more first layers and underlying the one or more second layers. Preferably, the one or more third layers comprises a material that is different to the material of the one or more second layers. Preferably, the one or more third layers comprise paper.

[0153] Forming the tubular element may comprise forming an intermediate tube comprising the one or more third layers between the inner tube and the outer tube. Preferably, the intermediate tube comprises a material that is different to the outer tube material. Preferably, the intermediate tube has a third compressive stiffness, wherein the second compressive stiffness is less than the third compressive stiffness.

[0154] Advantageously, providing the one or more third layers between the inner tube and the outer tube may provide support to allow the one or more second layers to be wound up around the one or more first layers and the mandrel. Advantageously, providing the one or more thirdlayers between the inner tube and the outer tube may provide a suitable surface to provide adhesive to in order to attach the one or more second layers to the one or more first layers.

[0155] Forming the intermediate tube may comprise forming the one or more third layers by winding a plurality of substantially continuous third strips between the plurality of substantially continuous first strips and the plurality of substantially continuous second strips.

[0156] Forming the intermediate tube and the outer tube may comprise forming a laminate. Forming the laminate may comprise providing an adhesive between the one or more third layers and the one or more second layers. Forming the laminate may comprise pressing the one or more third layers and the one or more second layers between a pair of rollers. Forming the laminate may comprise wrapping the inner tube in the one or more third layers and the one or more second layers to form the intermediate tube and the outer tube around the inner tube. Preferably, the rollers are configured to compress the outer tube material only in the elastic region of deformation.

[0157] The method may comprise compressing the one or more second layers.

[0158] Advantageously, compressing the one or more second layers during manufacture of the aerosol-generating article may temporarily increase the rigidity of the outer tube material and may reduce or prevent damage to the one or more second layers as a result of the friction exerted by components used in the manufacturing method. Advantageously, compressing the one or more second layers during manufacture of the aerosol-generating article may assist in conveying a helical movement to the other layers of the tubular element to facilitate the winding of one or more of the plurality of substantially continuous first strips, second strips and third strips in a spiral.

[0159] The method may comprise allowing the one or more second layers to expand after the outer tube is formed.

[0160] Advantageously, allowing the one or more second layers to expand after the outer tube is formed may facilitate the outer tube having a second compressive stiffness that is less than the first compressive stiffness.

[0161] An outer surface of the outer tube may define an outermost surface of the tubular element. The method may comprise forming a wrapper comprising one or more wrapping layers comprising a wrapping material. Preferably, forming the wrapper comprises winding a plurality of substantially continuous wrapping strips around the outer tube. Preferably, the wrapping material is paper. Preferably, the grammage of the one or more wrapper layers is less than the grammage of the one or more second layers.

[0162] The method may comprise allowing the outer tube to expand after the wrapper has been formed around the outer tube such that the wrapper at least partially restricts the expansion of the outer tube.

[0163] Advantageously, allowing the outer tube to expand after the wrapper has been formed around the outer tube such that the wrapper at least partially restricts the expansion of the outer tube may improve control over the second compressive stiffness of the outer tube.Preferably, an inner surface of each of the plurality of substantially continuous wrapping strips are coated with an adhesive.

[0164] The method may comprise simultaneously folding the one or more first layers and the one or more second layers overlying the one or more first layers to form the inner tube and the outer tube around the inner tube.

[0165] The one or more first layers and the one or more second layers may be moved along a linear moving path. The one or more first layers and the one or more second layers may be progressively folded. In particular, the one or more first layers and the one or more second layers may be progressively folded as the one or more first layers and the one or more second layers are moved along the linear moving path.

[0166] The method may comprise providing one or more wrapper layers comprising a wrapping material, the one or more wrapper layers overlying the one or more second layers. Preferably, the wrapping material is paper.

[0167] The method may comprise simultaneously folding the one or more first layers, the one or more second layers and the one or more wrapper layers. The one or more first layers, the one or more second layers and the one or more wrapper layers may be progressively folded as the one or more first layers and the one or more second layers are moved along a linear moving path.

[0168] The method may comprise providing an adhesive between each of the one or more first layers and the one or more second layers. The method may comprise providing an adhesive between each of the one or more first layers, the one or more second layers and the one or more wrapping layers. The method may comprise pressing the one or more first layers and the one or more second layers, for example between a pair of rollers. The method may comprise pressing the one or more first layers, the one or more second layers and the one or more wrapping layers, for example between a pair of rollers.

[0169] The method may comprise arranging part of the one or more wrapper layers to protrude beyond an outer edge of both the one or more first layers and the one or more second layers such that the one or more wrapper layers form a wrapping tab. The method may comprise providing an adhesive on an inner surface of the wrapping tab. The method may comprise contacting the adhesive with the outermost surface of the one or more wrapper layers. In other words, the wrapping tab may be contacted with the one or wrapper layers. Alternatively, the method may comprise contacting the adhesive with the outermost surface of the one or more second layers.

[0170] Advantageously, contacting the adhesive with the outermost surface of the one or more second layers may avoid an overlap of the wrapping tab with the one or more wrapping layers, which could protrude from the outer tube, and therefore may provide a smoother outermost surface of the tubular element.Preferably, the adhesive used in construction of the tubular element may be provided as a plurality of discrete portions of adhesive.

[0171] Advantageously, providing the adhesive as a plurality of discrete portions of adhesive may reduce the effect of the adhesive on the second compressive stiffness of the outer tube. In particular, providing the adhesive as a plurality of discrete portions of adhesive may prevent the adhesive from restricting expansion of the outer tube following compression. For example, where the outer tube material is an open-celled porous foam, providing the adhesive as a plurality of discrete portions of adhesive may reduce any effects resulting from any adhesive entering the pores of the foam.

[0172] Preferably, the adhesive comprises one or both of ethylene-vinyl acetate or poly-vinyl acetate.

[0173] Preferably, the adhesive used in construction of the tubular element is a heat sensitive adhesive.

[0174] Advantageously, providing the adhesive as a heat sensitive adhesive may reduce the effect of the adhesive on the second compressive stiffness of the outer tube. In particular, heat can be applied selectively to certain locations of the outer tube. Furthermore, heat can be applied after the outer tube has been allowed to expand following compression. Therefore, providing a heat-sensitive adhesive may prevent the adhesive from undesirably restricting expansion of the outer tube following compression. For example, where the outer tube material is an open-celled porous foam, providing a heat sensitive adhesive may reduce any effects resulting from any adhesive entering the pores of the foam.

[0175] 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.

[0176] Example EX1: An aerosol-generating article for use with an aerosol-generating device, the aerosol-generating article comprising:

[0177] a rod of aerosol-generating substrate; and

[0178] a tubular element comprising:

[0179] an inner tube comprising one or more first layers, the inner tube comprising a cellulosic material;

[0180] an outer tube arranged around the inner tube, the outer tube comprising one or more second layers,

[0181] wherein the inner tube has a first compressive stiffness and the outer tube has a second compressive stiffness,

[0182] wherein the second compressive stiffness is less than the first compressive stiffness,preferably wherein the outer tube has a wall thickness that is greater than a wall thickness of the inner tube.

[0183] Example EX2: An aerosol-generating article according to example EX1 , wherein the outer tube comprises an outer tube material, preferably wherein the cellulosic material has a first Young’s modulus in a direction perpendicular to a longitudinal axis of the tubular element and the outer tube material has a second Young’s modulus in a direction perpendicular to a longitudinal axis of the tubular element, and wherein the second Young's modulus is less than the first Young's modulus

[0184] Example EX3: An aerosol-generating article according to example EX1 or EX2, wherein the cellulosic material is selected from one or both of cardboard and paper.

[0185] Example EX4: An aerosol-generating article according to any one of examples EX1 to EX3, wherein the grammage of the one or more first layers is greater than or equal to 40 grams per square metre, optionally greater than or equal to 100 grams per square metre, or optionally greater than or equal to 170 grams per square metre.

[0186] Example EX5: An aerosol-generating article according to any preceding example, wherein the grammage of the one or more first layers is less than or equal to 250 grams per square metre, optionally less than or equal to 200 grams per square metre, optionally less than or equal to 150 grams per square metre, optionally less than or equal to 120 grams per square metre.

[0187] Example EX6: An aerosol-generating article according to any preceding example, wherein an inner surface of the inner tube defines an innermost surface of the tubular element.

[0188] Example EX7: An aerosol-generating article according to any one of examples EX2 to EX6, wherein the outer tube material is a non-woven material, preferably one or more of BioLace, lyocell or viscose.

[0189] Example EX8: An aerosol-generating article according to any one of examples EX2 to EX7, wherein the outer tube material comprises an open cell foam or a closed cell foam.

[0190] Example EX9: An aerosol-generating article according to any preceding example, wherein the second Young's modulus is greater than or equal to 1 kilopascal, optionally greater than or equal to 2 kilopascals, optionally greater than or equal to 10 kilopascals, optionally greater than or equal to 50 kilopascals, optionally greater than or equal to 250 kilopascals, or optionally greater than or equal to 1 megapascal.

[0191] Example EX10: An aerosol-generating article according to any preceding example, wherein the second Young's modulus is less than or equal to 2 megapascals, optionally less than or equal to 1 megapascal, optionally less than or equal to 500 kilopascals, optionally less than or equal to 100 kilopascals, optionally less than or equal to 50 kilopascals, optionally less than or equal to 10 kilopascals or optionally less than or equal to 5 kilopascals.Example EX11: An aerosol-generating article according to any preceding example, wherein the outer tube is elastically compressible when the compressive strain is less than or equal to 50 percent.

[0192] Example EX12: An aerosol-generating article according to any preceding example, wherein the outer tube has a wall thickness of greater than or equal to 0.2 millimetres, preferably greater than or equal to 0.5 millimetres, or more preferably greater than or equal to 0.8 millimetres.

[0193] Example EX13: An aerosol-generating article according to any preceding example, wherein the outer tube has a wall thickness of greater than or equal to 2 millimetres, preferably less than or equal to 1.2 millimetre or more preferably less than or equal to 1 millimetre.

[0194] Example EX14: An aerosol-generating article according to any preceding example, wherein an outer surface of the outer tube defines an outermost surface of the tubular element.

[0195] Example EX15: An aerosol-generating article according to any preceding example, wherein the tubular element comprises a wrapper, the wrapper comprising one or more wrapper layers comprising a wrapping material, preferably wherein the wrapping material is paper.

[0196] Example EX16: An aerosol-generating article according to example EX15, wherein the wrapper is arranged around the outer tube, preferably wherein an outer surface of the wrapper defines an outermost surface of the tubular element

[0197] Example EX17: An aerosol-generating article according to any one of example EX15 or EX16, wherein the grammage of the wrapper is less than the grammage of the outer tube.

[0198] Example EX18: An aerosol-generating article according to any preceding example, wherein the outer tube has an internal diameter that is substantially the same as an external diameter of the inner tube.

[0199] Example EX19: An aerosol-generating article according to any one of examples EX1 to EX17, wherein the tubular element comprises an intermediate tube arranged between the inner tube and the outer tube, wherein the intermediate tube comprises one or more third layers, preferably the one or more third layers comprise paper.

[0200] Example EX20: An aerosol-generating article according to example EX19, wherein the intermediate tube has a third compressive stiffness, wherein the second compressive stiffness is less than the third compressive stiffness.

[0201] Example EX21: An aerosol-generating article according to any preceding example, wherein an external diameter of the aerosol-generating article is between 5.5 millimetres and 8 millimetres.

[0202] Example EX22: An aerosol-generating article according to any preceding example, wherein a length of the aerosol-generating article is between 40 millimetres and 150 millimetres.

[0203] Example EX23: An aerosol-generating article according to any preceding example, wherein the tubular element is downstream of the rod of aerosol-generating substrate, preferably wherein the tubular element abuts a downstream end of the rod of aerosol-generating substrate.Example EX24: An aerosol-generating article according to any preceding example, comprising a susceptor element embedded in the rod of aerosol-generating substrate.

[0204] Example EX25: An aerosol-generating article according to example EX24, wherein an internal diameter of the tubular element is less than a width of the susceptor element.

[0205] Example EX26: An aerosol-generating article according to any preceding example, comprising a mouthpiece element downstream of the tubular element, preferably wherein the mouthpiece element abuts a downstream end of the tubular element.

[0206] Example EX27: An aerosol-generating article according to any preceding example, comprising an upstream element defining an upstream end of the aerosol-generating article, wherein the upstream element is upstream of the rod of aerosol-generating substrate, preferably wherein the upstream element abuts an upstream end of the rod of aerosol-generating substrate.

[0207] Example EX28: An aerosol-generating article according to any preceding example, comprising an outer wrapper circumscribing the tubular element and the rod of aerosol-generating substate.

[0208] Example EX29: An aerosol-generating system, the aerosol-generating system comprising:

[0209] an aerosol-generating article according to any preceding example; and an aerosol-generating device configured to receive the aerosol-generating article, wherein the aerosol-generating device is configured to heat the aerosol-generating article when the aerosol-generating article is received in the aerosol-generating device. Example EX30: An aerosol-generating system according to example EX29, wherein the aerosol-generating device comprises a device cavity configured to receive the aerosol-generating article, preferably wherein the device cavity is configured to receive the tubular element of the aerosol-generating article.

[0210] Example EX31: An aerosol-generating system according to example EX30, wherein the aerosol-generating device comprises one or more protrusions extending into the device cavity.

[0211] Example EX32: An aerosol-generating system according to example EX31 , where the one or more protrusions are arranged to compress at least part of the outer tube of the tubular element when the aerosol-generating article is received in the aerosol-generating device.

[0212] Example EX33: An aerosol-generating system according to example EX31 or EX32, where the one or more protrusions are arranged to compress the outer tube of the tubular element by a compressive strain of less than or equal to 50 percent when the aerosol-generating article is received in the aerosol-generating device.

[0213] Example EX34: An aerosol-generating system according to example EX31 or EX32, where the one or more protrusions are arranged to compress the outer tube of the tubular element by a compressive strain of greater than or equal to 50 percent when the aerosol-generating article is received in the aerosol-generating device.Example EX35: An aerosol-generating system according to any one of examples EX31 to EX34 when dependent on example EX19 or EX20, where the one or more protrusions are arranged to deform the intermediate tube when the aerosol-generating article is received in the aerosol-generating device.

[0214] Example EX36: An aerosol-generating system according to any one of examples EX31 to EX35, where the one or more protrusions are arranged to deform the inner tube when the aerosolgenerating article is received in the aerosol-generating device.

[0215] Example EX37: An aerosol-generating system according to any one of examples EX31 to EX36, wherein the aerosol-generating system comprises a heater element configured to heat the aerosol-generating article.

[0216] Example EX38: An aerosol-generating system according to example EX37, wherein the aerosol-generating device comprises the heater element.

[0217] Example EX39: An aerosol-generating system according to example EX37, wherein the aerosol-generating article comprises the heater element.

[0218] Example EX40: An aerosol-generating system according to any one of examples EX37 to EX39, wherein the heater element is a susceptor element, preferably wherein the aerosolgenerating device comprises an inductor coil configured to heat the susceptor element.

[0219] Example EX41: An aerosol-generating system according to any one of examples EX39 to EX40, wherein the heater element is a resistive heater element.

[0220] Example EX42: A method of manufacturing an aerosol-generating article comprising a tubular element, the method comprising:

[0221] providing one or more first layers comprising a cellulosic material;

[0222] providing one or more second layers,

[0223] overlying the one or more second layers on the one or more first layers; forming a tubular element comprising an inner tube and an outer tube around the inner tube, the inner tube comprising the one or more first layers and the outer tube comprising the one or more second layers,

[0224] wherein the inner tube has a first compressive stiffness and the outer tube has a second compressive stiffness, and

[0225] wherein the second compressive stiffness is less than the first compressive stiffness; and

[0226] providing a rod of aerosol-generating substrate,

[0227] preferably wherein the outer tube has a wall thickness that is greater than a wall thickness of the inner tube.

[0228] Example EX43: A method according to example EX42, comprising forming a tube comprising the one or more second layers around the one or more first layers, and cutting thetube to form the tubular element comprising the inner tube and the outer tube around the inner tube.

[0229] Example EX44: A method according to example EX42 or EX43, comprising combining the tubular element and the rod of aerosol-generating substrate.

[0230] Example EX45: A method according to any one of examples EX42 to EX44, comprising forming the inner tube from the one or more first layers; and wrapping the inner tube in the one or more second layers to form the outer tube around the inner tube.

[0231] Example EX46: A method according to example EX45, wherein forming the inner tube comprises forming the one or more first layers by winding a plurality of substantially continuous first strips, preferably comprising winding the plurality of substantially continuous first strips around a cylindrical mandrel.

[0232] Example EX47: A method according to any one of examples EX42 to EX46, wherein the plurality of substantially continuous first strips are wound in a spiral, preferably wherein the pitch of the spiral is equal to a width of each of the plurality of substantially continuous first strips.

[0233] Example EX48: A method according to any one of examples EX42 to EX47, wherein forming the outer tube comprises forming the one or more second layers by winding a plurality of substantially continuous second strips around the inner tube, preferably wherein the plurality of substantially continuous second strips are wound in a spiral, preferably wherein the pitch of the spiral is equal to a width of each of the plurality of substantially continuous second strips.

[0234] Example EX49: A method according to any one of examples EX42 to EX48, wherein an inner surface of each of the plurality of substantially continuous first strips other than the innermost substantially continuous first strip is coated with an adhesive.

[0235] Example EX50: A method according to any one of examples EX42 to EX49, wherein an inner surface of each of the plurality of substantially continuous second strips is coated with an adhesive.

[0236] Example EX51: A method according to any one of examples EX42 to EX50, comprising providing one or more third layers overlying the one or more first layers and underlying the one or more second layers, preferably the one or more third layers comprise paper.

[0237] Example EX52: A method according to example EX51, wherein forming the tubular element comprises forming an intermediate tube comprising the one or more third layers between the inner tube and the outer tube, preferably wherein the intermediate tube has a third compressive stiffness, wherein the second compressive stiffness is less than the third compressive stiffness.

[0238] Example EX53: A method according to example EX51 or EX52, wherein forming the intermediate tube comprises forming the one or more third layers by winding a plurality of substantially continuous third strips between the plurality of substantially continuous first strips and the plurality of substantially continuous second strips.Example EX54: A method according to example EX51 or EX52, wherein forming the intermediate tube and the outer tube comprises:

[0239] forming a laminate by providing an adhesive between the one or more third layers and the one or more second layers;

[0240] pressing the one or more third layers and the one or more second layers between a pair of rollers; and

[0241] wrapping the inner tube in the one or more third layers and the one or more second layers to form the intermediate tube and the outer tube around the inner tube,

[0242] preferably wherein the rollers are configured to compress the outer tube material only in the elastic region of deformation.

[0243] Example EX55: A method according to any one of examples EX42 to EX54, comprising compressing the one or more second layers.

[0244] Example EX56: A method according to example EX55, comprising allowing the one or more second layers to expand after the outer tube is formed.

[0245] Example EX57: A method according to any one of examples EX42 to EX56 wherein an outer surface of the outer tube defines an outermost surface of the tubular element.

[0246] Example EX58: A method according to any one of examples EX42 to EX56, comprising forming a wrapper comprising one or more wrapping layers comprising a wrapping material by winding a plurality of substantially continuous wrapping strips around the outer tube, preferably wherein the wrapping material comprises paper.

[0247] Example EX59: A method according to example EX56 and example EX58, comprising allowing the outer tube to expand after the wrapper has been formed around the outer tube such that the wrapper at least partially restricts the expansion of the outer tube.

[0248] Example EX60: A method according to example EX58 or EX59, wherein an inner surface of each of the plurality of substantially continuous wrapping strips are coated with an adhesive.

[0249] Example EX61: A method according to any one of examples EX42 to EX44, comprising simultaneously folding the one or more first layers and the one or more second layers overlying the one or more first layers to form the inner tube and the outer tube around the inner tube.

[0250] Example EX62: A method according to example EX61 , wherein the one or more first layers and the one or more second layers are progressively folded as the one or more first layers and the one or more second layers are moved along a linear moving path.

[0251] Example EX63: A method according to example EX61 or EX62, comprising providing one or more wrapper layers comprising a wrapping material, the one or more wrapper layers overlying the one or more second layers; and simultaneously folding the one or more first layers, the one or more second layers and the one or more wrapper layers, preferably wherein the wrapping material comprises paper.Example EX64: A method according to any one of examples EX61 to EX63, comprising providing an adhesive between each of the one or more first layers, the one or more second layers and the one or more wrapping layers, and pressing the one or more first layers, the one or more second layers and the one or more wrapping layers between a pair of rollers.

[0252] Example EX65: A method according to any one of examples EX61 to EX64, comprising: arranging part of the one or more wrapper layers to protrude beyond an outer edge of both the one or more first layers and the one or more second layers such that the one or more wrapper layers form a wrapping tab; and

[0253] providing an adhesive on an inner surface of the wrapping tab, and contacting the adhesive with the outermost surface of either: the one or more wrapper layers or the one or more second layers.

[0254] Example EX66: A method according to one of examples EX42 to EX65, comprising providing the adhesive as a plurality of discrete portions of adhesive.

[0255] Example EX67: A method according to one of examples EX42 to EX66, wherein the adhesive is a heat sensitive adhesive.

[0256] Example EX68: A method according to one of examples EX42 to EX67, wherein the adhesive comprises one or both of ethylene-vinyl acetate or poly-vinyl acetate.

[0257] Example EX69: A method of manufacturing an aerosol-generating article according to one of examples EX42 to EX68, comprising: aligning the tubular element with the rod of aerosolgenerating substrate along a longitudinal axis; and wrapping the tubular element and the rod of aerosol-generating substrate in an outer wrapper.

[0258] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which:

[0259] Figure 1 is perspective view of a tubular element according to a first embodiment of the disclosure.

[0260] Figure 2 is perspective view of a tubular element according to a second embodiment of the disclosure.

[0261] Figure 3 is a cross-sectional view of an aerosol-generating article comprising a tubular element according to a first embodiment of the disclosure.

[0262] Figure 4 is cross-sectional view of an aerosol-generating system comprising an aerosolgenerating article according to a first embodiment of the disclosure and an aerosol-generating device.

[0263] Figure 5 shows a schematic side view of an apparatus used in a method for forming the tubular element of the first embodiment of the disclosure.

[0264] Figure 6 shows a simplified schematic side view of an apparatus used in a method for forming the tubular element of the second embodiment of the disclosure.Figure 7 shows a schematic perspective view of the apparatus of Figure 6, with additional detail.

[0265] Figure 1 shows a perspective view of a tubular element 100. The tubular element 100 comprises an inner tube 102 comprising one or more first layers. The inner tube 102 comprises a cellulosic material.

[0266] The tubular element 100 comprises an outer tube 104 arranged around the inner tube 102. The outer tube 104 comprises one or more second layers. The outer tube 104 comprises an outer tube material. The outer tube material is a non-woven material. The outer tube 104 has an internal diameter that is substantially the same as an external diameter of the inner tube 102.

[0267] The inner tube 102 has a first compressive stiffness and the outer tube 104 has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness.

[0268] An inner surface of the inner tube 102 defines an innermost surface of the tubular element 100 and defines a lumen 106. The lumen 106 defines an internal air path through the tubular element 100.

[0269] The tubular element 100 comprises a wrapper 108. The wrapper 108 comprises one or more wrapper layers comprising a wrapping material. The wrapping material is paper. The wrapper 108 is arranged around the outer tube 104. An outer surface of the wrapper 108 defines an outermost surface of the tubular element 100.

[0270] Figure 2 shows a perspective view of a tubular element 200. The tubular element 200 comprises an inner tube 202 comprising one or more first layers. The inner tube 202 comprises a cellulosic material.

[0271] The tubular element 200 comprises an outer tube 204 arranged around the inner tube 202. The outer tube 204 comprises one or more second layers. The outer tube 204 comprises an outer tube material. The outer tube material is a non-woven material. An outer surface of the outer tube 204 defines an outermost surface of the tubular element 200.

[0272] The inner tube 202 has a first compressive stiffness and the outer tube 204 has a second compressive stiffness. The second compressive stiffness is less than the first compressive stiffness.

[0273] An inner surface of the inner tube 202 defines an innermost surface of the tubular element 200 and defines a lumen 206. The lumen 206 defines an internal air path through the tubular element 200.

[0274] The tubular element 200 comprises an intermediate tube 208 arranged between the inner tube 202 and the outer tube 204. The intermediate tube 208 comprises one or more third layers. The one or more third layers comprise paper. The intermediate tube 208 has a third compressive stiffness. The second compressive stiffness is less than the third compressive stiffness.

[0275] Figure 3 shows a schematic cross-sectional view of an aerosol-generating article 300.The aerosol-generating article 300 has a substantially cylindrical shape along its length. The aerosol-generating article 300 comprises a rod of aerosol-generating substrate 302. The rod of aerosol-generating substrate 302 comprises tobacco. A susceptor element 303 having a planar shape is embedded in the rod of aerosol-generating substrate 302.

[0276] The aerosol-generating article 300 comprises the tubular element 100 of Figure 1. The tubular element 100 is downstream of the rod of aerosol-generating substrate 302. The tubular element 100 abuts a downstream end of the rod of aerosol-generating substrate 302. An internal diameter of the tubular element 100 is less than a width of the susceptor element 303.

[0277] It will be appreciated that an aerosol-generating article could be provided that is substantially the same as the aerosol-generating article 300 but comprises the tubular element 200 of Figure 2, instead of the tubular element 100.

[0278] A mouthpiece element 304 is provided downstream of the tubular element 100. The mouthpiece element 304 abuts a downstream end of the tubular element 100. The mouthpiece element 304 defines a proximal end of the aerosol-generating article 300.

[0279] An upstream element 306 defines a distal end of the aerosol-generating article 300. The upstream element 306 is upstream of the rod of aerosol-generating substrate 302. The upstream element 306 abuts an upstream end of the rod of aerosol-generating substrate 302.

[0280] A longitudinal axis extends centrally along a longitudinal direction of the aerosolgenerating article 300.

[0281] The upstream element 306, the rod of aerosol-forming substrate 302, the tubular element 100, and the mouthpiece element 304 are arranged end-to-end along the longitudinal axis, and are circumscribed by an outer wrapper 308, which extends along the entire length of the aerosolgenerating article 300.

[0282] Figure 4 shows a cross-sectional view of a portion of an aerosol-generating system 500 comprising the aerosol-generating article 300 of Figure 3 and an aerosol-generating device 400.

[0283] The aerosol-generating device 400 is configured to receive the aerosol-generating article 300. The aerosol-generating device 400 is configured to heat the aerosol-generating article 300 when the aerosol-generating article 300 is received in the aerosol-generating device 400.

[0284] The aerosol-generating system 500 comprises a device cavity 402 configured to receive the aerosol-generating article 300. In particular, the device cavity 402 is configured to receive at least the rod of aerosol-generating substrate 302 and the tubular element 100 of the aerosolgenerating article 300.

[0285] The aerosol-generating device 400 comprises one or more protrusions 404 extending into the device cavity 402. The one or more protrusions 404 are arranged to compress at least part of the outer tube 104 of the tubular element 100 when the aerosol-generating article 300 is received in the aerosol-generating device 400.The aerosol-generating device 400 comprises an inductor coil 406 configured to heat the susceptor element 303 embedded in the rod of aerosol-generating substrate 302.

[0286] In use, a user inserts the aerosol-generating article 300 into the device cavity 402 of the aerosol-generating device 400, such that the susceptor element 303 is surrounded by the inductor coil 406. The rod of aerosol-generating substrate 302 is then inductively heated to generate an aerosol that is inhaled by the user.

[0287] Figure 5 shows a schematic perspective view of the apparatus 600 for forming the tubular element 100.

[0288] The one or more wrapping layers 606 is arranged to overlie the one or more second layers 604, and the one or more second layers 604 is arranged to overlie the one or more first layers 602. An adhesive is provided between each of the one or more first layers 602, the one or more second layers 604 and the one or more wrapping layers 606, and the layers pressed between a pair of rollers (not shown).

[0289] The one or more first layers 602, the one or more second layers 604 and the one or more wrapping layers 606 are then simultaneously folded to form the inner tube 102, the outer tube 104 and the wrapper 108 respectively as the one or more first layers 602, the one or more second layers 604 and the one or more wrapping layers 606 are moved along a linear moving path 608.

[0290] Part of the one or more wrapper layers 606 protrudes beyond an outer edge of both the one or more first layers 602 and the one or more second layers 604 such that the one or more wrapper layers form a wrapping tab 610. An adhesive is provided on an inner surface of the wrapping tab 610 using a nozzle 612 and the adhesive is contacted with the outermost surface of the one or more second layers 604.

[0291] Figure 6 shows a schematic side view of a portion of an apparatus 700 for forming the tubular element 200 from a plurality of substantially continuous strips 702, 704, 706 being spirally wound around a mandrel 710.

[0292] The inner tube 202 is formed by forming the one or more first layers by winding the plurality of the substantially continuous first strips 702 around the mandrel 710. The outer tube 204 is formed by forming the one or more second layers by winding the plurality of substantially continuous second strips 706 around the inner tube 202. The intermediate tube 208 is formed by forming the one or more third layers by winding a plurality of substantially continuous third strips 704 between the plurality of substantially continuous first strips 702 and the plurality of substantially continuous second strips 706.

[0293] Each of the plurality of strips 702, 704, 706 has the same width and is fed to the mandrel 710 at an angle 712 relative to the longitudinal axis of the mandrel 710.

[0294] The strips 702, 704 and 706 are arranged in a partially overlapping manner and form further partially overlapping layers of a tube 2000. Strip 702 forms an innermost layer and strip 706 forms an outermost layer. The overlapping strips 702, 704, 706 help to strengthen the tube2000 with the overlapping portions of the strips 702, 704, 706 reinforcing the points of the tube where the side edges of the strips 702, 704, 706 are adjoined.

[0295] The innermost strip 702 has no adhesive coating, while the other strips 704, 706 have an adhesive coating that covers substantially the entirety of their inner surface. The outer surface of the strips 704, 706 are not coated with adhesive.

[0296] The pitch of a helical full turn of a strip 702, 704, 706 around the mandrel 710 is equal to a width of the strip 702, 704, 706. As the tube 2000 is formed by winding the strips 702, 704, 606 around one end of the mandrel 710, it extends in length and advances towards the other end (not shown) of the mandrel 710, from where it is removed.

[0297] Figure 7 shows a schematic perspective view of the apparatus 700 of Figure 6 showing further features.

[0298] A drive unit 712 is provided at a first end of the mandrel 710 which rotates the mandrel 710 in a clockwise direction about a longitudinal axis of the mandrel 710 at the desired rotational speed. As the tube 2000 is formed by spirally winding the strips 702, 704, 706 around the mandrel 710, the tube 2000 is also pulled along the mandrel 710 by an elastic belt 714 wrapped around the external surface of the tube 2000 and driven endlessly by two vertical drums or rollers 716 on either side of the tube 2000. As a result, at least part of the tube 2000 is compressed.

[0299] The apparatus 700 comprises a cutter (not shown) that cuts the tube 2000 exiting the mandrel 710 into the tube segment 200. The aerosol-generating article is then formed by combining the tubular element 200 and the rod of aerosol-generating substrate 302.

[0300] It will be appreciated that the apparatus 700 may instead form the tubular element 100 by forming the one or more wrapping layers by winding a plurality of substantially continuous wrapping strips around the outer tube, and omitting the plurality of substantially continuous third strips 704.

[0301] 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". In this context, therefore, a number A is understood as A ± 10 percent 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

- 32 -Claims1. An aerosol-generating article for use with an aerosol-generating device, the aerosolgenerating article comprising:a rod of aerosol-generating substrate; anda tubular element comprising:an inner tube comprising one or more first layers, the inner tube comprising a cellulosic material;an outer tube arranged around the inner tube, the outer tube comprising one or more second layers,wherein the inner tube has a first compressive stiffness and the outer tube has a second compressive stiffness,wherein the second compressive stiffness is less than the first compressive stiffness, and wherein the outer tube has a wall thickness that is greater than a wall thickness of the inner tube.

2. An aerosol-generating article according to claim 1, wherein the outer tube material is a non-woven material, preferably one or more of BioLace, lyocell or viscose.

3. An aerosol-generating article according to claim 1 or 2, wherein an outer surface of the outer tube defines an outermost surface of the tubular element.

4. An aerosol-generating article according to claim 1 or 2, wherein the tubular element comprises a wrapper, the wrapper comprising one or more wrapper layers comprising a wrapping material, wherein the wrapper is arranged around the outer tube.

5. An aerosol-generating article according to any preceding claim, wherein the tubular element comprises an intermediate tube arranged between the inner tube and the outer tube, wherein the intermediate tube comprises one or more third layers.

6. An aerosol-generating article according to any preceding claim, wherein the tubular element is downstream of the rod of aerosol-generating substrate.

7. An aerosol-generating article according to any preceding claim, comprising a susceptor element embedded in the rod of aerosol-generating substrate.- 33 -8. An aerosol-generating article according to claim 7, wherein an internal diameter of the tubular element is less than a width of the susceptor element.

9. An aerosol-generating article according to any preceding claim, comprising a mouthpiece element downstream of the tubular element.

10. An aerosol-generating system, the aerosol-generating system comprising:an aerosol-generating article according to any preceding claim; and an aerosol-generating device configured to receive the aerosol-generating article, wherein the aerosol-generating device is configured to heat the aerosol-generating article when the aerosol-generating article is received in the aerosol-generating device.

11. An aerosol-generating system according to claim 10, wherein the aerosol-generating device comprises a device cavity configured to receive the aerosol-generating article, and wherein the aerosol-generating device comprises one or more protrusions extending into the device cavity.

12. An aerosol-generating system according to claim 11 , where the one or more protrusions are arranged to compress at least part of the outer tube of the tubular element when the aerosolgenerating article is received in the aerosol-generating device.

13. A method of manufacturing an aerosol-generating article comprising a tubular element, the method comprising:providing one or more first layers comprising a cellulosic material;providing one or more second layers,overlying the one or more second layers on the one or more first layers; forming a tubular element comprising an inner tube and an outer tube around the inner tube, the inner tube comprising the one or more first layers and the outer tube comprising the one or more second layers,wherein the inner tube has a first compressive stiffness and the outer tube has a second compressive stiffness,wherein the second compressive stiffness is less than the first compressive stiffness, andwherein the outer tube has a wall thickness that is greater than a wall thickness of the inner tube; andproviding a rod of aerosol-generating substrate.

14. A method according to claim 13, comprising forming the inner tube from the one or more first layers; and wrapping the inner tube in the one or more second layers to form the outer tube around the inner tube.

15. A method according to claim 13, comprising simultaneously folding the one or more first layers and the one or more second layers overlying the one or more first layers to form the inner tube and the outer tube around the inner tube.

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