Aerosol-generating article with tubular section having an end face with a convex curvature

Abstract

An aerosol-generating article is provided, including: a substrate section including aerosol-forming substrate; and a tubular section with a sidewall circumscribing a hollow interior, the tubular section being located downstream of the substrate section, an upstream end of the sidewall including an upstream end face comprising a convex curvature, a part of the tubular section being positioned adjacent to the substrate section, the sidewall of the tubular section further including a ventilation zone, and the ventilation zone including perforations in the sidewall. An aerosol-generating system including an aerosol-generating device including a cavity, and the aerosol-generating article, is also provided.

Description

[0001] The present disclosure relates to an aerosol-generating article for an aerosol-generating device, wherein the aerosol-generating article comprises a substrate section and a tubular section. The present disclosure further relates to an aerosol-generating system comprising the aerosol-generating article and an aerosol-generating device. The present disclosure also relates to the use of a tubular section for cooling an aerosol.

[0002] It is known to provide an aerosol-generating article with a substrate section and a hollow tubular section. The substrate section may comprise aerosol-forming substrate. The article may be inserted into the cavity of an aerosol-generating article for heating the substrate section. Such devices may heat the aerosol-forming substrate to a temperature at which one or more components of the aerosol-forming substrate are volatilized without burning the aerosol-forming substrate. The tubular section may serve to cool down an aerosol generated from the aerosol-forming substrate of the substrate section. This may assist in the generation of an aerosol. This may prevent the burning of a user if the aerosol is too hot. The tubular section often affects the resistance to draw of the aerosol-generating article. The tubular section also may not provide enough support for the substrate section when a heating element is inserted into the substrate section. This may lead to a dislocation of the substrate section relative to the tubular section. The tubular section also may affect the aerosol formation within the aerosol-generating article.

[0003] It would be desirable to provide an aerosol-generating article providing a cooling of the aerosol generated. It also would be desirable to provide an aerosol-generating article improving the aerosol generation. It also would be desirable to provide an aerosol-generating article with improved support for the substrate section when a heating element is inserted into the substrate section.

[0004] According to an embodiment of the invention there is provided an aerosol-generating article. The aerosol-generating article may comprise a substrate section. The substrate section may comprise aerosol-forming substrate. The aerosol-generating article may furthermore comprise a tubular section with a sidewall circumscribing a hollow interior. The tubular section may be located downstream of the substrate section. An upstream end of the sidewall may comprise an upstream end face comprising a convex curvature.

[0005] Another embodiment of the invention may provide an aerosol-generating article. The aerosol-generating article comprises a substrate section, wherein the substrate section comprises aerosol-forming substrate. The aerosol-generating article furthermore comprises a tubular section with a sidewall circumscribing a hollow interior. The tubular section is located downstream of the substrate section. An upstream end of the sidewall comprises an upstream end face comprising a convex curvature.

[0006] The aerosol-generating article may provide additional support to the substrate section owing to the tubular section with the upstream end face having a convex curvature. The resistance to draw of the aerosol-generating article may be improved due to the tubular section. The aerosol-generating article may exhibit an improved aerosol generation due to the tubular section.

[0007] The term “convex curvature” describes that the surface of the upstream end face is curved outwards with respect to the hollow interior of the tubular section. The term “convex curvature” is meant to describe a surface with does not form a flat plane.

[0008] The term “convex curvature” also may describe that a part of the surface of the upstream end face may bulge outwards with respect to the hollow interior of the tubular section.

[0009] As used herein, the terms “upstream”, and “downstream”, are used to describe the relative positions of sections of the aerosol-generating article or an aerosol-generating device used together with the aerosol-generating article in relation to the direction in which the aerosol is transported through the aerosol-generating article during use. The aerosol-generating article according to the invention comprises a proximal end through which, in use, an aerosol exits the aerosol-generating article. The proximal end of the aerosol generating device may also be referred to as the mouth end or the downstream end. In use, a user draws on the downstream or mouth end of the aerosol-generating article in order to inhale an aerosol generated by the aerosol-generating system. The aerosol-generating system comprises an upstream end opposed to the downstream or mouth end. The mouth end is downstream of the distal end. The distal end of the aerosol-generating device or aerosol-generating article may also be referred to as the upstream end. Components, or portions of components, of the aerosol-generating article or the aerosol-generating device may be described as being upstream or downstream of one another based on their relative positions to the direction in which the aerosol is transported through the aerosol-generating article or the aerosol-generating device during use of the article or the aerosol generating device.

[0010] The term “aerosol-generating article” is used herein to denote an article wherein an aerosol generating substrate is heated to produce an inhalable aerosol to a consumer. As used herein, the term “aerosol-forming substrate” denotes a substrate capable of releasing volatile compounds upon heating to generate an aerosol.

[0011] A radius of curvature of the convex curvature may be between 1.3 millimeters and 2.3 millimeters, preferably between 1.6 millimeters and 2.0 millimeters, more preferably between 1.7 millimeters and 1.9 millimeters, more preferably about 1.8 millimeters. The upstream end face may have a rounded shape.

[0012] A part of the upstream end face may be bent to extend into the hollow interior of the tubular section.

[0013] This may allow to direct an airflow entering the tubular section through the upstream end face directly into the tubular section. This may improve the aerosolization. This may also improve the resistance-to-draw value of the tubular section.

[0014] The upstream end face may circumscribe a central aperture. The upstream end face may form a tubular upstream end portion extending from the central aperture into the hollow interior of the tubular section.

[0015] The central aperture may advantageously allow an airflow originating from the substrate section to enter the tubular section. The tubular upstream end portion may direct the air flow into the hollow interior of the tubular section. This may improve the aerosolization process. This may advantageously cool an aerosol formed from air and volatile compounds of the aerosol-forming substrate.

[0016] The upstream end face may comprise an upstream part of the upstream end face. This upstream part of the end face may be the part of the upstream end face which is located the most upstream in the aerosol-generating article in comparison to other parts of the upstream end face. This upstream part of the upstream end face may be arranged the closest to the substrate section in the aerosol-generating article in comparison to other parts of the upstream end face. In particular, the upstream part of the upstream end face may be spaced apart from the substrate section at the most by 5 millimeters, preferably less than 1 millimeter. Most preferably, the upstream part of the upstream end face may be arranged adjacent to the substrate section.

[0017] The upstream end face may comprise a downstream part of the upstream end face. This downstream part of the end face may be the part of the upstream end face which is located the most downstream in the aerosol-generating article in comparison to other parts of the upstream end face. This downstream part of the end face may be the part of the upstream end face extending into the hollow interior of the tubular section.

[0018] The aerosol-generating article may be configured to be used in conjunction with an aerosol-generating device. The aerosol-generating article may be configured to be insertable into a cavity of the aerosol-generating device. The aerosol-generating device may be configured to heat the aerosol-forming substrate of the substrate section to a temperature below the combustion temperature of the substrate for generating an aerosol.

[0019] A part of the tubular section may be positioned adjacent to the substrate section.

[0020] This may ensure a higher mechanical stability of the substrate section. This may provide additional support to the substrate section owing to the upstream end face with the convex curvature. This may provide additional stability to the substrate section if a heating element, for example a heating blade is inserted into the substrate section.

[0021] A part of the tubular section may be positioned adjacent to the substrate section. This may advantageously support the substrate section.

[0022] The aerosol-generating article may further comprise a longitudinal axis. A part of the sidewall of the tubular section may extend along the longitudinal axis. A transversal part of the upstream end face of the sidewall may extend transversely to the longitudinal axis. The transversal part of the upstream end face of the sidewall may extend partly perpendicular to the longitudinal axis.

[0023] The transversal part of the upstream end face of the sidewall may comprise or may form the upstream part of the upstream end face. This part of the upstream end face may be the part located most upstream in the aerosol-generating article in comparison to other parts of the upstream end face.

[0024] The transversal part of the upstream end face of the sidewall may provide additional stability to the upstream end face and the upstream end of the tubular section.

[0025] As used herein, the term “longitudinal” refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream and downstream ends of the aerosol-generating article.

[0026] Preferably the transversal part of the upstream end face may be adjacent to the substrate section. This may ensure that the upstream end face of the tubular section can support the substrate section. This may allow an easy transport of aerosol generated in the substrate section through the upstream end face into the hollow interior of the substrate section.

[0027] Preferably the transversal part of the upstream end face of the tubular portion of the tubular section may be in direct contact with a downstream portion of the substrate section.

[0028] The tubular section may comprise or consist of a cellulose-based material, preferably paper or cardboard. This may provide additional stability to the tubular section. This may additionally support the substrate section. The cellulose-based material may be sustainable and biodegradable.

[0029] The substrate section may have a length of between 10 to 13 millimeters, preferably 11 millimeters to 12 millimeters. The length of an optional upstream filter plug may be between 4 millimeters to 6 millimeters, preferably 5 millimeters. The diameter of all the sections of the aerosol-generating article may be between 6 millimeters to 8 millimeters, preferably 7.1 millimeters to 7.3 millimeters. A thickness of the sidewall of the tubular section circumscribing the hollow interior may be between 140 micrometers to 610 micrometers, preferably 150 micrometers to 600 micrometers. A diameter of the central aperture of the upstream end face of the tubular section may be between 0.8 millimeters to 3.2 millimeters, preferably between 1 millimeter to 3 millimeters. The length of the downstream filter section may be between 7 millimeters to 12 millimeters.

[0030] The sidewall of the tubular section further may comprise a ventilation zone. The ventilation zone may include perforations in the sidewall. The perforations may allow air to enter the hollow interior of the tubular section. The perforations may provide an additional cooling effect for the aerosol formed from the aerosol-forming substrate of the substrate section. Preferably, the ventilation zone may be located downstream of the upstream end of the sidewall. This may allow air to enter the hollow interior of the tubular section through the perforations and further being mixed with the airflow originating from the substrate section. The ventilation zone may improve the resistance to draw (RTD) value of the aerosol-generating article.

[0031] Because the ventilated hollow tubular element substantially does not contribute to the overall RTD of the aerosol-generating article, in aerosol-generating articles in accordance with the invention the overall RTD of the article can advantageously be fine-tuned by adjusting the length and density of the rod of aerosol-generating substrate and optionally the length and density of a segment of filtration material forming part of the mouthpiece or the length and density of a segment of filtration material provided upstream of the aerosol-generating substrate. In effect, in aerosol-generating articles in accordance with the present invention, the cavity internally defined by the hollow tubular segment enables a substantially unrestricted flow of the aerosol from an upstream end of the hollow tubular segment to a downstream end of the hollow tubular segment. This means that the cavity is substantially empty or behaves, from the viewpoint of resisting to flow, as if it were substantially empty. Thus, aerosol-generating articles that have a predetermined RTD can be manufactured consistently and with great precision, such that satisfactory levels of RTD can be provided for the consumer even in the presence of ventilation.

[0032] The aerosol-generating article may further comprise a filter section. The filter section may be located downstream of the tubular section. The filter section may be a mouthpiece filter section. The filter section may be used by a user consuming the aerosol-generating article for inhaling the aerosol generated from the aerosol-forming substrate.

[0033] The substrate section may comprise a heating element. The heating element may be configured to heat the aerosol-forming substrate. Preferably, the heating element may be a susceptor heating element.

[0034] In general, the susceptor is a material that is capable of absorbing electromagnetic energy and converting it to heat. When located in an alternating electromagnetic field, typically eddy currents are induced and hysteresis losses occur in the susceptor causing heating of the susceptor. Changing electromagnetic fields generated by one or several induction coils heat the susceptor, which then transfers the heat to the aerosol-generating article, such that an aerosol is formed. The heat transfer may be mainly by conduction of heat. Such a transfer of heat is best, if the susceptor is in close thermal contact with the aerosol-generating article.

[0035] The susceptor heating element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. A preferred susceptor heating element may comprise or consist of a ferromagnetic material, for example a ferromagnetic alloy, ferritic iron, or a ferromagnetic steel or stainless steel. A suitable susceptor may be, or comprise, aluminium. Preferred susceptors may be heated to a temperature in excess of 250 degrees Celsius.

[0036] Preferred susceptors are metal susceptors, for example stainless steel. However, susceptor materials may also comprise or be made of graphite, molybdenum, silicon carbide, aluminum, niobium, Inconel alloys (austenite nickel-chromium-based superalloys), metallized films, ceramics such as for example zirconia, transition metals such as for example iron, cobalt, nickel, or metalloids components such as for example boron, carbon, silicon, phosphorus, aluminium.

[0037] Preferably, the susceptor material is a metallic susceptor material.

[0038] The aerosol generating article may further comprise an upstream filter section. The upstream filter section may be located upstream of the substrate section.

[0039] The upstream filter section may provide additional support to the substrate section. The upstream filter section may avoid accidental leakage of aerosol-generating substrate out of the aerosol-forming article.

[0040] The aerosol-forming substrate may comprise an aerosol-former. Preferably the aerosol-former may be selected from polyhydric alcohols, esters of polyhydric alcohols, or aliphatic esters of mono-, di- or polycarboxylic acids or a combination thereof. The aerosol-former may be present in an amount of between 10 weight percent to 50 weight percent on a dry weight basis based on the total amount of the aerosol-forming substrate.

[0041] The term “dry weight basis” throughout the application refers to the weight of the aerosol-forming substrate calculated with the water removed via Karl-Fischer titration, for example after being heated to a temperature of 110 degrees Celsius at standard conditions for temperature and pressure and using potentiometry to determine the endpoint. The end point is detected by a bipotentiometric titration method. A second pair of Pt electrodes is immersed in the anode solution. The detector circuit maintains a constant current between the two detector electrodes during titration. Prior to the equivalence point, the solution contains I-, but little I2. At the equivalence point, excess I2 appears and an abrupt voltage drop marks the endpoint. The amount of charge needed to generate I2 and reach the endpoint can then be used to calculate the amount of water in the original sample. The aerosol-former content can be measured by gas chromatography in combination with a flame ionization detector.

[0042] The aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise an aerosol former that facilitates the formation of a dense and stable aerosol. Suitable aerosol-formers are well known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, 1,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetra-decanedioate. Aerosol formers may be polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1,3-butanediol and glycerine. The aerosol-former may be propylene glycol. The aerosol former may comprise both glycerine and propylene glycol.

[0043] The aerosol-forming substrate may be a solid aerosol-generating substrate.

[0044] In certain preferred embodiments, the aerosol-forming substrate comprises homogenised plant material, preferably a homogenised tobacco material.

[0045] As used herein, the term “homogenised plant material” encompasses any plant material formed by the agglomeration of particles of plant. For example, sheets or webs of homogenised tobacco material for the aerosol-forming substrates of the present invention may be formed by agglomerating particles of tobacco material obtained by pulverising, grinding or comminuting plant material and optionally one or more of tobacco leaf lamina and tobacco leaf stems. The homogenised plant material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

[0046] The homogenised plant material can be provided in any suitable form. For example, the homogenised plant material may be in the form of one or more sheets. As used herein with reference to the invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.

[0047] Alternatively, or in addition, the homogenised plant material may be in the form of a plurality of pellets or granules.

[0048] Alternatively, or in addition, the homogenised plant material may be in the form of a plurality of strands, strips or shreds. As used herein, the term “strand” describes an elongate element of material having a length that is substantially greater than the width and thickness thereof. The term “strand” should be considered to encompass strips, shreds and any other homogenised plant material having a similar form. The strands of homogenised plant material may be formed from a sheet of homogenised plant material, for example by cutting or shredding, or by other methods, for example, by an extrusion method.

[0049] In some embodiments, the strands may be formed in situ within the aerosol-generating substrate as a result of the splitting or cracking of a sheet of homogenised plant material during formation of the aerosol-generating substrate, for example, as a result of crimping. The strands of homogenised plant material within the aerosol-generating substrate may be separate from each other. Alternatively, each strand of homogenised plant material within the aerosol-generating substrate may be at least partially connected to an adjacent strand or strands along the length of the strands. For example, adjacent strands may be connected by one or more fibres. This may occur, for example, where the strands have been formed due to the splitting of a sheet of homogenised plant material during production of the aerosol-generating substrate, as described above.

[0050] Preferably, the aerosol-forming substrate is in the form of one or more sheets of homogenised plant material. In various embodiments of the invention, the one or more sheets of homogenised plant material may be produced by a casting process. In various embodiments of the invention, the one or more sheets of homogenised plant material may be produced by a paper-making process. The one or more sheets as described herein may each individually have a thickness of between 100 micrometres and 600 micrometres, preferably between 150 micrometres and 300 micrometres, and most preferably between 200 micrometres and 250 micrometres. Individual thickness refers to the thickness of the individual sheet, whereas combined thickness refers to the total thickness of all sheets that make up the aerosol-forming substrate. For example, if the aerosol-forming substrate is formed from two individual sheets, then the combined thickness is the sum of the thickness of the two individual sheets or the measured thickness of the two sheets where the two sheets are stacked in the aerosol-forming substrate.

[0051] The one or more sheets as described herein may each individually have a grammage of between about 100 grams per square metre and about 300 grams per square metre.

[0052] The one or more sheets as described herein may each individually have a density of from about 0.3 grams per cubic centimetre to about 1.3 grams per cubic centimetre, and preferably from about 0.7 grams per cubic centimetre to about 1.0 gram per cubic centimetre.

[0053] Volatile compounds, such as tobacco flavors from the plant material or the above-mentioned aerosol formers from the aerosol-forming substrate may evaporate during heating of the aerosol-forming substrate. As the released volatile compounds cool, they may condense to form an aerosol. The tubular section with the upstream end face comprising the convex curvature may assist in cooling and in the formation of the aerosol.

[0054] The upstream end of the sidewall may have a higher density than a downstream end of the sidewall. This may provide additional mechanical stability to the tubular section. Such a tubular section may be able to better support the substrate section.

[0055] The upstream end of the sidewall may have a higher thickness than a downstream end of the sidewall. This may also provide additional mechanical stability to the tubular section. A tubular section with an upstream end having a higher thickness may also advantageously provide additional support to the substrate section.

[0056] The upstream end face comprising the convex curvature may be curled. Curling may be a method of manufacturing able to provide a tubular section with an upstream end face with a convex curvature. Curling may also be a method of manufacturing producing a downstream end of the sidewall having one or both of a higher density and a higher thickness than the downstream end of the sidewall.

[0057] The curling may comprise the following steps of providing a curling tool with a curling surface. The method may also provide the method step of providing the tubular section with an open tubular end. Curling the open tubular end of the tubular section may be performed by translationally advancing the curling tool towards the open end so that the curling surface contacts the open tubular end. Simultaneously, the curling surface may be rotated to produce the end of the sidewall comprising the convex curvature.

[0058] The curling tool may comprise a curling mechanism configured for linearly advancing the curling tool along the longitudinal center axis and, simultaneously, rotating the curling tool around the longitudinal center axis. The curling mechanism may be driven by one or more motors. The curling mechanism may comprise means for transmitting power from the one or more motors to the curling head.

[0059] The curling mechanism may be configured for linearly advancing the curling tool over a distance of between 1 millimeter and 10 millimeters, preferably of between 3 millimeters and 7 millimeters, more preferably of about 5 millimeters.

[0060] The curling mechanism may be configured for linearly advancing the curling tool at a speed of between 1 millimeter per second and 10 millimeters per second, preferably between 3 millimeters per second and 7 millimeters per second, more preferably about 5 millimeters per second.

[0061] The curling mechanism may be configured for linearly advancing the curling tool at a force of between 1 Newton and 20 Newtons, preferably between 3 Newtons and 15 Newtons, more preferably between 5 Newtons and 10 Newtons.

[0062] The curling mechanism may be configured for rotating the curling tool at a speed of between 50 rounds per minute and 2.000 rounds per minute, preferably between 100 rounds per minute and 1.500 rounds per minute, more preferably between 300 rounds per minute and 1.200 rounds per minute.

[0063] A maximum diameter of the circular opening may be between 5 millimeters and 10 millimeters, preferably between 6 millimeters and 9 millimeters.

[0064] A base of the recess may comprise a centrally arranged protrusion extending along the longitudinal center axis towards the proximal end.

[0065] The centrally arranged protrusion may be cone-shaped. The centrally arranged protrusion may be pin-shaped. A pin-shape may be described as a cone shape, wherein the lateral surface comprises a concave curvature.

[0066] The centrally arranged protrusion may be shaped as a truncated pin or cone.

[0067] The centrally arranged protrusion may be hourglass-shaped.

[0068] A length of the centrally arranged protrusion may be between 0.3 millimeter and 3 millimeters, preferably between 0.5 millimeter and 2 millimeters, more preferably between 0.8 millimeter and 1.2 millimeters, more preferably about 1 millimeter.

[0069] At least a portion of a sidewall of the centrally arranged protrusion may be arranged as a curling surface. The curling surface of the sidewall of the recess may be a first curling surface and the curling surface of the sidewall of the centrally arranged protrusion may be a second curling surface. The second curling surface may comprise a concave curvature.

[0070] A maximum depth of the recess parallel to the longitudinal axis may be between 1 millimeter and 15 millimeters, preferably between 4 millimeters and 10 millimeters, more preferably between 5 millimeters and 8 millimeters.

[0071] A radius of curvature of the concave curvature of one or both of the first and second curling surfaces may be between 10% and 40%, preferably between 20% and 30%, more preferably about 25%, of a maximum diameter of the circular opening. As used herein, the “radius of curvature of the concave curvature” may relate to one or both of the first and second curling surfaces. Radii of curvature of the concave curvature of the first and second curling surfaces may be identical or may be different.

[0072] The method of curling may comprise, before the step of curling the open tubular end of the tubular section, a step of pretreating the open tubular end of the tubular section. The pretreatment may comprise wetting the open tubular end with an aqueous solution, for example in form of a spray mist. The aqueous solution may be water-based and may comprise additives. The open tubular end may be only slightly wetted. By wetting the open tubular end, the humidity of the tubular wall of the tubular section may be increased.

[0073] The pretreatment may comprise treating the open tubular end of the tubular section with vapor or steam. The pretreatment may comprise heating the open tubular end, for example to temperatures in the range of 30° C. to 200° C.

[0074] The pretreatment may improve curling of the open tubular end of the tubular section. The pretreatment may particularly improve curling of the open tubular end when the open tubular end comprises cardboard or paper.

[0075] The pretreatment may increase the elasticity of the edge.

[0076] The invention also provides an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating device including a cavity. The aerosol-generating system may also comprise an aerosol-generating article as described herein. The cavity may be configured to receive said aerosol-generating article.

[0077] Another embodiment of the invention provides an aerosol-generating system. The aerosol-generating system comprises an aerosol-generating device including a cavity. The aerosol-generating system also comprises an aerosol-generating article as described herein. The cavity of the aerosol-generating device is configured to receive said aerosol-generating article.

[0078] Such an aerosol-generating system may be configured to generate an aerosol-forming substrate by heating the aerosol-generating article received in the cavity of the device.

[0079] The cavity of the aerosol-generating device may comprise inner walls with sections protruding inwards into the cavity. These protruding sections may contact the aerosol-generating article received in the cavity. These protruding sections may allow the formation of an air flow path between the inner walls of the cavity and the aerosol-generating article. This may also allow the formation of an airflow path leading to the above-described ventilation zone of the aerosol-generating article.

[0080] The aerosol-generating device may include a heating element, in particular an inductive heating element, such as an inductive coil. Upon inductive heating of the aerosol-forming substrate of the aerosol-generating article received in the aerosol-generating device, the susceptor heating element of the substrate section may be heated by the alternating magnetic field of the inductive heating element. This may also heat the aerosol-forming substrate. For induction heating, the heating element preferably comprises an induction coil. An alternating current may be supplied to the induction coil for generating an alternating magnetic field. The alternating current may have a high frequency. As used herein, the term “high frequency oscillating current” means an oscillating current having a frequency of between 500 kilohertz and 30 megahertz. The high frequency oscillating current may have a frequency of from about 1 megahertz to about 30 megahertz, preferably from about 1 megahertz to about 10 megahertz and more preferably from about 5 megahertz to about 8 megahertz.

[0081] The heating element may be configured to heat the aerosol-generating article to a temperature ranging from 220 degrees Celsius to 400 degrees Celsius, preferably from 250 degrees Celsius to 290 degrees Celsius. The heating element may be configured to heat the aerosol-generating article, in particular the aerosol-forming substrate to a temperature below the combustion temperature of the aerosol-forming substrate. This may allow the use of an aerosol generated from a “heat not burn” aerosol-generating article.

[0082] The heating element may be configured as a resistive heating element. The heating element may be configured as a resistive heating coil, at least partly surrounding the cavity, for receiving the aerosol-generating article.

[0083] The heating element may be located adjacent to the cavity for receiving the aerosol-generating article. The heating element may be located at least partly around the cavity for heating an aerosol-generating article received in the cavity. The heating element may surround a perimeter of the cavity for receiving the aerosol-generating article. This may allow a reliable and uniform heating of the substrate section of the aerosol-generating article.

[0084] The heating element may comprise an electrically resistive material. Suitable electrically resistive materials include but are not limited to: semiconductors such as doped ceramics, electrically “conductive” ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum platinum, gold and silver. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium-titanium-zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold-and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetal® and iron-manganese-aluminium based alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required.

[0085] The resistive heating element mentioned above also may be part of the substrate section of the aerosol-generating article. In this case, the aerosol-generating device may comprise electrical connections in order to heat the resistive heating element in the substrate section.

[0086] The invention also provides the use of a tubular element for cooling an aerosol generated from an aerosol-forming substrate. The tubular element may comprise a sidewall circumscribing a hollow interior. An end portion of the side wall may comprise an end face with a convex curvature.

[0087] Another embodiment of the invention provides the use of a tubular element for cooling an aerosol generated from an aerosol-forming substrate. The tubular element comprises a sidewall circumscribing a hollow interior. An end portion of the sidewall comprises an end face with a convex curvature.

[0088] Such a use of a tubular element for cooling an aerosol may provide a better cooling of the aerosol compared to conventional tubular elements lacking the end face with the convex curvature. This may also provide additional support to a substrate section including the aerosol-forming substrate.

[0089] The invention also provides a method for producing an aerosol-generating article comprising a substrate section in the tubular section. The method may provide the method step of providing a tubular section with a sidewall circumscribing a hollow interior. The tubular section may have an open end. Furthermore, the method may comprise the method step of providing a curling tool with a curling surface. Curling the open tubular end of the tubular section may be performed by translationally advancing the curling tool towards the open end so that the curling surface contacts the open tubular end. Simultaneously, the curling surface may be rotated to produce an end face of the sidewall comprising a convex curvature. The method may furthermore comprise the method step of providing a substrate section comprising an aerosol-forming substrate. The substrate section may be arranged relative to the tubular section so that the end face of the sidewall of the tubular section comprising the convex curvature is located adjacent to the substrate section. This may produce the aerosol-generating article.

[0090] Another embodiment of the invention provides a method for producing an aerosol-generating article comprising a substrate section and the tubular section. The method comprises the method steps of providing a tubular section with a sidewall circumscribing a hollow interior, wherein the tubular section has an open end. A curling tool is provided with a curling surface. The method also comprises the method step of curling the open tubular end of the tubular section by translationally advancing the curling tool towards the open end so that the curling surface contacts the open tubular end. Simultaneously the curling surface is rotated in order to produce an end face of the sidewall comprising a convex curvature. The method also comprises the method step of providing a substrate section comprising an aerosol-forming substrate. The substrate section is arranged relative to the tubular section so that the end face of the sidewall of the tubular section comprising the convex curvature is located adjacent to the substrate section, thereby producing the aerosol-generating article.

[0091] Such a method for producing is an easy method for providing aerosol-generating articles including the substrate section and the tubular section with the upstream end face comprising a convex curvature according to the present invention.

[0092] This may provide a method for producing an aerosol-generating article which reliably and reproducibly allow automatic manufacturing of the article. This also may allow producing the aerosol-generating article with sufficiently high speed. This may allow to manufacture the aerosol-generating article with a tubular section having uniform appearance.

[0093] By curling the open tubular end of the tubular section, a curled end face of the tubular end with increased mechanical stability may be provided. A method for producing a structurally reinforced aerosol-generating article may be provided. The curled end face of the tubular section may provide an increased hardness. The curled end face may provide additional support and stability to the substrate section of the aerosol-generating article. The curled end face with the convex curvature may also be less prone to deformation.

[0094] The tubular section may comprise a longitudinal axis, preferably a central longitudinal axis. During the step of translationally advancing the curling tool towards the open end and simultaneously rotating the curling surface of the curling tool, the open end of the tubular section may be folded towards the central longitudinal axis of the tubular section.

[0095] The method may further comprise the method step of attaching the substrate section to the tubular section. This may increase the stability of the aerosol-generating article. Preferably the substrate section is attached to the tubular section by wrapping a paper at least partly around the substrate section and the tubular section. This wrapping paper may provide additional stability to the aerosol-generating article. This wrapping paper may allow an easy arrangement of the substrate section relative to the tubular section. The wrapping paper may be a one-piece member wrapped around at least parts of the substrate section and the tubular section for connecting both sections.

[0096] A curling tool may be employed having a concavely shaped curling surface. This may allow the easy formation of the upstream end face with the convex curvature during the curling procedure.

[0097] Preferably, the curling surface of the curling tool comprises a concave curvature. More preferably the curling surface is arranged rotationally symmetric around a center axis.

[0098] 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.

[0099] Example E1: An aerosol-generating article, comprising

[0100] a substrate section, the substrate section comprising aerosol-forming substrate,

[0101] a tubular section with a sidewall circumscribing a hollow interior, the tubular section being located downstream of the substrate section, wherein an upstream end of the sidewall comprises an upstream end face comprising a convex curvature.

[0102] Example E2: The aerosol-generating article according to example E1, wherein a part of the upstream end face is bent to extend into the hollow interior of the tubular section.

[0103] Example E3: The aerosol-generating article according to any of the preceding examples, wherein the upstream end face circumscribes a central aperture, preferably wherein the upstream end face forms a tubular upstream end portion extending from the central aperture into the hollow interior of the tubular section.

[0104] Example E4: The aerosol-generating article according to any of the preceding examples, wherein a part of the tubular section is positioned adjacent to the substrate section.

[0105] Example E5: The aerosol-generating article according to any of the preceding examples, further comprising a longitudinal axis, wherein a transversal part of the upstream end face of the sidewall extends transversally to the longitudinal axis, preferably, wherein the transversal part of the upstream end face is adjacent to the substrate section, more preferably wherein the transversal part of the upstream end face of the tubular portion is in direct contact with a downstream portion of the substrate section.

[0106] Example E6: The aerosol-generating article according to any of the preceding examples, wherein the tubular section comprises or consists of a cellulose-based material, preferably paper or cardboard.

[0107] Example E7: The aerosol-generating article according to any of the preceding examples, wherein the sidewall of the tubular section further comprises a ventilation zone, wherein the ventilation zone comprises perforations in the sidewall, preferably wherein the ventilation zone is located downstream of the upstream end of the sidewall.

[0108] Example E8: The aerosol-generating article according to any of the preceding examples, further comprising a filter section, wherein the filter section is located downstream of the tubular section, preferably wherein the filter section is a mouthpiece filter section.

[0109] Example E9: The aerosol-generating article according to any of the preceding examples, wherein the substrate section comprises a heating element, wherein the heating element is configured to heat the aerosol-forming substrate, preferably wherein the heating element is a susceptor heating element.

[0110] Example E10: The aerosol-generating article according to any of the preceding examples, further comprising an upstream filter section, wherein the upstream filter section is located upstream of the substrate section.

[0111] Example E11: The aerosol-generating article according to any of the preceding examples, wherein the aerosol-forming substrate comprises an aerosol-former, preferably wherein the aerosol-former is selected from polyhydric alcohols, esters of polyhydric alcohols, or aliphatic esters of mono-, di-or polycarboxylic acids or a combination thereof, more preferably wherein the aerosol-former is present in an amount of between 10 weight percent to 50 weight percent on a dry weight basis based on the total amount of the aerosol-forming substrate.

[0112] Example E12: The aerosol-generating article according to any of the preceding examples, wherein the upstream end of the sidewall has a higher density than a downstream end of the sidewall.

[0113] Example E13: The aerosol-generating article according to any of the preceding examples, wherein the upstream end of the sidewall has a higher thickness than a downstream end of the sidewall.

[0114] Example E14: The aerosol-generating article according to any of the preceding examples, wherein the upstream end face comprising the convex curvature is curled.

[0115] Example E15: The aerosol-generating article according to the preceding example, wherein the curling comprises the following steps of:

[0116] providing a curling tool with a curling surface,

[0117] providing the tubular section with an open tubular end, and

[0118] curling the open tubular end of the tubular section by translationally advancing the curling tool towards the open end so that the curling surface contacts the open tubular end and simultaneously rotating the curling surface to produce the end of the sidewall comprising the convex curvature.

[0119] Example E16: Aerosol-generating system, comprising an aerosol-generating device including a cavity, and an aerosol-generating article according to any one of the preceding examples, wherein the cavity is configured to receive said aerosol-generating article.

[0120] Example E17: The aerosol-generating system according to the preceding example, wherein the aerosol-generating article comprises a susceptor heating element and the aerosol-generating device comprises an induction coil configured to generate an alternating magnetic field in the susceptor heating element.

[0121] Example E18: The aerosol-generating system according to example E16, wherein the aerosol-generating device comprises a heating element at least partly surrounding the cavity, wherein the heating element is configured for heating said aerosol-generating article received in the cavity.

[0122] Example E19: Use of a tubular element for cooling an aerosol generated from an aerosol-forming substrate, wherein the tubular element comprises a sidewall circumscribing a hollow interior, wherein an end portion of the sidewall comprises an end face with a convex curvature.

[0123] Example E20: Method for producing an aerosol-generating article comprising a substrate section and a tubular section, the method comprising the method steps of:

[0124] providing a tubular section with a sidewall circumscribing a hollow interior, wherein the tubular section has an open end,

[0125] providing a curling tool with a curling surface,

[0126] curling the open tubular end of the tubular section by translationally advancing the curling tool towards the open end so that the curling surface contacts the open tubular end and simultaneously rotating the curling surface to produce an end face of the sidewall comprising a convex curvature, and

[0127] providing a substrate section comprising an aerosol-forming substrate, and

[0128] arranging the substrate section relative to the tubular section so that the end face of the sidewall of the tubular section comprising the convex curvature is located adjacent to the substrate section, thereby producing the aerosol-generating article.

[0129] Example E21: Method for producing an aerosol-generating article according to the preceding example, further comprising the method step of:

[0130] attaching the substrate section to the tubular section, preferably wherein the substrate section is attached to the tubular section by wrapping a paper at least partly around the substrate section and the tubular section.

[0131] Example E22: Method for producing an aerosol-generating article according to any of the examples E20 or E21, wherein the curling surface is concavely shaped and, preferably wherein the curling surface comprises a concave curvature, more preferably wherein the curling surface is arranged rotationally symmetric around a center axis.

[0132] Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

[0133] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0134] FIG. 1 shows a cross-sectional view of an aerosol-generating article according to an embodiment of the invention

[0135] FIG. 2 shows a cross-sectional view of a cut-out of the tubular section with an upstream end face comprising a convex curvature;

[0136] FIG. 3 shows a photography of three tubular sections with upstream end faces having convex curvatures; and

[0137] FIG. 4a to 4c depict cross-sectional views of different method steps for producing an aerosol-generating article according to an embodiment of a method of the invention.

[0138] In the following elements with the same functionality are marked with the same reference numerals throughout all the figures.

[0139] FIG. 1 shows a cross-sectional view of an aerosol-generating article 10 including a tubular section 12 with an optional downstream filter section 20 and a substrate section 14. The substrate section 14 may optionally contain a heating element 16 which either may be a susceptor for inductive heating or a resistive heating element for heating the aerosol-forming substrate included in the substrate section. The tubular section 12 is located downstream of the substrate section 14 and comprises an upstream end face 12A with a convex curvature. The upstream end face 12A also includes a transversal part 12B of an upstream end face which extends transversal, in particular perpendicular to a central longitudinal axis 26 of the aerosol-generating article. At least this transversal part 12B directly contacts parts of the substrate section 14 and therefore supports the substrate section 14. This transversal part 12B forms the most upstream part of the upstream end face in comparison to other parts of the upstream end face. The upstream end face 12A with a convex curvature also may include an upstream end portion 12D of the end face extending into the hollow interior 12C of the tubular section 12. This upstream end portion 12D also can serve as an airflow guiding element directing the airflow originating from the substrate section 14 through the central aperture 15 of the upstream end face into the hollow interior 12C of the tubular section 12. This upstream end portion 12D forms the most downstream part of the upstream end face in comparison to other parts of the upstream end face. The tubular section 12 comprises a sidewall 13 circumscribing the hollow interior 12C. As shown in FIG. 1, parts of the sidewall 13 at the upstream end of the tubular section 12 form the upstream end face 12A with a convex curvature. The different sections of the aerosol-generating article 10 are held together by wrapping paper 18 which is at least partly wrapped around the substrate section 14, the tubular section 12 and the downstream filter section 20. A downstream part of the tubular section 12 comprises a ventilation zone 21 with perforations in the sidewall 13. This ventilation zone allows air to enter the hollow interior 12C of the tubular section 12. This air can be mixed with the airstream originating from the substrate section 14. This may allow for an improved process of the aerosolization and cooling down.

[0140] FIG. 2 depicts a cross-sectional view of a cut-out of a tubular section with the upstream end face 12A having convex curvature. This figure shows in greater detail the design of the upstream end face 12A with the upstream end portion 12D extending into the hollow interior 12C of the tubular section. The end face portion 12B extending transversal to the longitudinal axis 26 of either the aerosol-generating article or the tubular section self can be seen in greater detail.

[0141] FIG. 3 shows a photography of three separate tubular sections 12 showing their upstream end faces in greater detail. The upstream end faces circumscribe the respective central apertures 15. The apertures 15 allow the entry of an airflow coming from the substrate section into the hollow interior of the tubular section.

[0142] FIG. 4a depicts a cross-sectional view of a method step of providing a tubular section 12 with a sidewall circumscribing a hollow interior 12C which is connected to a downstream filter section 20, thereby forming the arrangement 11. The tubular section 12 comprises an open tubular end 23. A curling tool 22 with a curling surface 24 having a concave curvature with a central protrusion 25 is provided. The curling tool 22 is moved towards the arrangement 11 along the central axis 26 of both the curling tool and the tubular section.

[0143] FIG. 4b depicts the process step of translationally advancing the curling tool towards the open end 23 along the central axis 26 as indicated by the arrow 30. Simultaneously the curling tool 22 is rotated about the central axis 26 as indicated by the arrow 32 in order to curl the open tubular end 23. In FIG. 4B the axis of rotation coincides with the direction of translational advancement of the curling surface of the curling tool towards the open end of the tubular section. It is also possible that the axis of rotation may be tilted with respect to the translational movement along the central axis 26. For example, the axis of rotation may be tilted at an angle of less than 90 degrees, preferably less than 45 degrees more preferably less than 1 degree with respect to the direction of translational advancement of the curling surface along the central axis 26. The open tubular end is deformed during the simultaneous translational and rotational movement of the curling tool, forming the upstream end face with the convex curvature. The concave curvature of the curling surface of the curling tool ensures that an upstream end face with a convex curvature is formed. Additionally, the central protrusion 25 allows the central aperture 15 to be formed when the curling tool is translated towards the open tubular end and rotated at the same time. The final result of the curling procedure is shown in the cross-sectional view of FIG. 4c. The upstream end face 12A with the convex curvature is formed. The central aperture 15 is circumscribed by the upstream end face.

Claims

1. -14. (cancelled)15. An aerosol-generating article, comprising:a substrate section comprising aerosol-forming substrate; anda tubular section with a sidewall circumscribing a hollow interior, the tubular section being located downstream of the substrate section,wherein an upstream end of the sidewall comprises an upstream end face comprising a convex curvature,wherein a part of the tubular section is positioned adjacent to the substrate section,wherein the sidewall of the tubular section further comprises a ventilation zone, andwherein the ventilation zone comprises perforations in the sidewall.

16. The aerosol-generating article according to claim 15, wherein a part of the upstream end face is bent to extend into the hollow interior of the tubular section.

17. The aerosol-generating article according to claim 15, wherein the upstream end face circumscribes a central aperture.

18. The aerosol-generating article according to claim 17, wherein the upstream end face forms a tubular upstream end portion extending from the central aperture into the hollow interior of the tubular section.

19. The aerosol-generating article according to claim 15,further comprising a longitudinal axis,wherein a transversal part of the upstream end face of the sidewall extends transversally to the longitudinal axis.

20. The aerosol-generating article according to claim 19, wherein the transversal part of the upstream end face is adjacent to the substrate section.

21. The aerosol-generating article according to claim 19, wherein the transversal part of the upstream end face of the tubular portion is in direct contact to a downstream portion of the substrate section.

22. The aerosol-generating article according to claim 15, wherein the tubular section comprises a cellulose-based material.

23. The aerosol-generating article according to claim 15, wherein the ventilation zone is located downstream of the upstream end of the sidewall.

24. The aerosol-generating article according to claim 15, further comprising a filter section located downstream of the tubular section.

25. The aerosol-generating article according to claim 24, wherein the filter section is a mouthpiece filter section.

26. The aerosol-generating article according to claim 15,wherein the substrate section further comprises a heating element, andwherein the heating element is configured to heat the aerosol-forming substrate.

27. The aerosol-generating article according to claim 26, wherein the heating element is a susceptor heating element.

28. The aerosol-generating article according to claim 15, further comprising an upstream filter section located upstream of the substrate section.

29. The aerosol-generating article according to claim 15, wherein the aerosol-forming substrate comprises an aerosol-former.

30. The aerosol-generating article according to claim 29, wherein the aerosol-former is selected from polyhydric alcohols, esters of polyhydric alcohols, or aliphatic esters of mono-, di- or polycarboxylic acids, or a combination thereof.

31. The aerosol-generating article according to claim 29, wherein the aerosol-former is present in an amount of between 10 weight percent to 50 weight percent on a dry weight basis based on a total amount of the aerosol-forming substrate.

32. The aerosol-generating article according to claim 15, wherein the upstream end of the sidewall has a higher density than a downstream end of the sidewall.

33. The aerosol-generating article according to claim 15, wherein the upstream end of the sidewall has a higher thickness than a downstream end of the sidewall.

34. The aerosol-generating article according to claim 15, wherein the upstream end face comprising the convex curvature is curled.

35. An aerosol-generating system, comprising an aerosol-generating device including a cavity, and the aerosol-generating article according to claim 15, wherein the cavity is configured to receive the aerosol-generating article.

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