BR112018073559B1 - AEROSOL GENERATOR ARTICLE AND METHOD FOR FORMING THE AEROSOL GENERATOR ARTICLE - Google Patents

Abstract

An aerosol-generating article (2) comprises an aerosol-forming substrate (4), a combustible heat source (3) and at least one fiber-reinforced airgel layer (5) circumscribing at least a portion of the length of the heat source. fuel (3). The aerosol generating article (2) also comprises one or more air flow paths along which air can be drawn through the article (2) for inhalation by a user, and one or more non-combustible, substantially impermeable barriers to the air, between the fuel heat source (3) and the aerosol-forming substrate (4).

Description

[0001] The present invention relates to an aerosol-generating article comprising an aerosol-forming substrate and a combustible heat source and a method for forming such an aerosol-generating article.

[0002] Various aerosol generating articles in which tobacco is heated rather than combusted have been proposed in the art. One object of these 'heated' aerosol generating articles is to reduce known harmful smoke constituents of the type produced by the combustion and pyrolytic degradation of tobacco in combustible cigarettes. In a known type of heated aerosol generating article, an aerosol generated by transferring heat from a fuel heat source to an aerosol forming substrate located adjacent the fuel heat source. During aerosol generation, volatile compounds are released by the aerosol-forming substrate by heat transfer from the fuel heat source and entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol that is inhaled by the user.

[0003] The combustion temperature of the combustible heat source for use in a heated aerosol-generating article shall not be so high as to result in combustion or thermal degradation of the aerosol-forming substrate during use of the heated aerosol-generating article. However, the combustion temperature of the fuel heat source must be high enough to generate enough heat to release enough volatile compounds from the aerosol-forming substrate to produce an acceptable aerosol, especially during the first few puffs.

[0004] A variety of combustible heat sources for use in heated aerosol generating articles have been proposed in the art. The combustion temperature of combustible heat sources for use in heated aerosol generating articles is typically between about 600°C and 800°C.

[0005] It is known to wrap an insulating member around the periphery of the combustible heat source of a heated aerosol generating article to reduce the surface temperature of the heated aerosol generating article. However, it has been discovered that such insulating members can reduce the temperature of the fuel heat source during combustion of the fuel heat source, potentially reducing the effectiveness of the heat source in heating the aerosol-forming substrate to generate an aerosol. This effect is especially pronounced if an insulating member extends substantially the length of the combustible heat source. Such insulating members may also inhibit sustained combustion of the combustible heat source, such that the duration of combustion of the combustible heat source is reduced.

[0006] It would be desirable to provide an aerosol generating article which has a low surface temperature close to the heat source, acceptable appearance and which can be assembled in a simple and reliable manner. It would also be desirable to provide an aerosol generating article that generates an acceptable aerosol during both initial puffs and final puffs.

[0007] According to a first aspect of the invention, there is provided an aerosol-generating article comprising an aerosol-forming substrate, a combustible heat source and at least one fiber-reinforced airgel layer circumscribing at least part of the length of the source of combustible heat. The aerosol generating article also comprises one or more air flow paths along which air can be drawn through the article for inhalation by a user, and one or more barriers substantially impermeable to non-combustible air between the combustible heat source and the aerosol-forming substrate. One or more substantially non-combustible air-impermeable barriers between the combustible heat source and the aerosol-forming substrate isolates the combustible heat source from one or more airflow paths such that, during use, entrained air through the aerosol generating article along one or more air flow paths does not come into direct contact with the combustible heat source.

[0008] During use, the combustible heat source may be ignited by an external heat source, such as a lighter, and may begin to ignite. The combustible heat source can heat the aerosol-forming substrate such that volatile compounds in the aerosol-forming substrate vaporize. When a user draws air into the aerosol-generating article, the air may be drawn into the aerosol-generating article along one or more airflow paths and mix with vapor from the heated aerosol-forming substrate to form an aerosol. The aerosol may be drawn out of the aerosol generating article and dispensed to the user for inhalation by the user.

[0009] At least one fiber-reinforced airgel layer circumscribing at least part of the length of the fuel heat source may be isolated from the fuel heat source. This can reduce the surface temperature of the aerosol generating article at the fuel heat source. The at least one fiber-reinforced airgel layer can also allow sufficient air through the layer such that combustion of the fuel heat source can be substantially unimpeded.

[00010] As used herein, the terms "airgel" and "unreinforced airgel" are used interchangeably to describe an open-pore foam. The airgel can be mesoporous. The term "mesoporous" refers to a material that contains pores ranging from about 2 nanometers to about 50 nanometers in diameter. The airgel can comprise a network of interconnected structures, the network of interconnected structures can be nanostructures. Airgel can exhibit a porosity of about 50 percent or more. Airgel can exhibit a porosity of about 90 percent or more. The airgel can be formed by removing the liquid component of a conventional gel. A conventional gel will be understood as a semi-solid colloidal suspension of a solid dispersed in a liquid.

[00011] Aerogels typically have low thermal conductivity. Without wanting to be bound by theory, conductive heat transfer is exhibited in aerogels due to their high porosity while convective heat transfer is inhibited in aerogels due to small pore diameters. The small pore diameter restricts air movement through the airgel.

[00012] As used herein, the term "fiber-reinforced airgel" refers to a composite material comprising an airgel matrix reinforced with a fibrous material. A fibrous material is understood to be a material comprising fibers.

[00013] Although aerogels can have an interconnected porous structure, the average pore width exhibited by unreinforced aerogels is similar to the medium of free movement of air molecules at room temperature. As a result, unreinforced aerogels have low air permeability. This is understood to be due to the Knudsen effect.

[00014] The average pore width exhibited by fiber-reinforced aerogels is greater than the medium of free movement of air molecules at room temperature. The wider pore width of air permeation fiber reinforced aerogels compared to non air permeation fiber reinforced aerogels reduces the impact of the Knudsen effect. As a result, fiber-reinforced aerogels have been found to have a higher air permeability than non-fiber-reinforced aerogels.

[00015] It has also been observed that fiber reinforced aerogels exhibit superior mechanical properties compared to unreinforced aerogels. For example, fiber-reinforced aerogels can be more flexible and more machinable than unreinforced aerogels.

[00016] At least one fiber-reinforced airgel layer circumscribes at least a portion of the length of the fuel heat source. At least one fiber-reinforced airgel layer of the present invention can substantially circumscribe the entire length of the combustible heat source. This may allow the aerosol generating article to benefit from the insulating properties of the fiber reinforced airgel, reducing the surface temperature near the heat source of the aerosol generating article at the fuel heat source and benefit from the air permeability of the airgel fiber reinforced, allowing sufficient ambient air to reach the fuel heat source for the fuel heat source to ignite and undergo substantially unimpeded combustion. It has been observed that a combustible heat source substantially circumscribed by at least one fiber-reinforced airgel layer allows a combustible heat source to burn at an elevated temperature and for a longer period of time compared to a combustible heat source that not be circumscribed by any layers of material.

[00017] The fiber-reinforced airgel of the present invention may also have a machinability that facilitates the formation of a layer of the fiber-reinforced airgel circumscribing at least a portion of the length of the heat source. As used herein, the term "layer" is used to describe a body of material generally conforming to the shape of the fuel heat source. The at least one fiber-reinforced airgel layer may be any suitable type of layer arranged to surround the heat source. Suitable layer types include, but are not limited to, casings and coatings. As used herein, the term "coating" is used to describe a layer of material that covers and adheres to the heat source.

[00018] At least one layer of fiber-reinforced airgel may be in direct contact with the fuel heat source. At least one fiber-reinforced airgel layer may be separated from the combustible heat source.

[00019] As used herein, the term "length" is used to describe the dimension of a component or a part of the aerosol-forming article in the longitudinal direction of the aerosol-generating article. At least one layer of fiber-reinforced airgel surrounds at least a portion of the length of the fuel heat source. For example, at least one fiber-reinforced airgel layer can surround about half the length of the fuel heat source. At least one fiber-reinforced airgel layer may encompass more than half the length of the fuel heat source. For example, at least one fiber-reinforced airgel layer can span from about 60 percent to about 100 percent of the length of the fuel heat source. At least one fiber-reinforced airgel layer can encompass at least about 70 percent of the length of the fuel heat source. At least one fiber-reinforced airgel layer can encompass at least about 80 percent of the length of the fuel heat source. At least one fiber-reinforced airgel layer can encompass at least about 90 percent of the length of the fuel heat source. At least one fiber-reinforced airgel layer may surround the full length of the combustible heat source. At least one fiber-reinforced airgel layer may substantially circumscribe the length of the fuel heat source.

[00020] At least one fiber-reinforced airgel layer may be sufficiently permeable to air to allow the fuel heat source to undergo substantially unimpeded combustion.

[00021] At least one fiber-reinforced airgel layer can circumscribe about half the length of the aerosol-forming substrate. Advantageously, the fiber-reinforced airgel surrounding the aerosol-forming substrate can lower the surface temperature of the aerosol-generating article on the aerosol-forming substrate.

[00022] At least one fiber-reinforced airgel layer may surround the fuel heat source at one end downstream of the fuel heat source. This can advantageously reduce the surface temperature of the aerosol generating article in the portion of the fuel heat source that is closest to the user during normal operation of the aerosol generating article.

[00023] At least one fiber-reinforced airgel layer may surround the fuel heat source at an upstream end of the fuel heat source.

[00024] At least one fiber-reinforced airgel layer may surround the fuel heat source at the upstream end and the downstream end.

[00025] The uncovered portions of the fuel heat source may be referred to herein as "bare" portions. At least one layer of the fiber-reinforced airgel of the present invention may be provided to cover or surround the "bare" or uncovered portions of the fuel heat source.

[00026] In some embodiments, a portion of the fuel heat source may be circumscribed by at least one additional layer at the upstream end. At least one additional layer can be a cigarette paper layer. In these embodiments, an upstream portion of the fuel heat source is a bare portion. In other words, an upstream portion of the fuel heat source is not covered by at least one additional layer. In these embodiments, at least one fiber-reinforced airgel layer may surround the upstream portion of the fuel heat source. At least one fiber-reinforced airgel layer may surround the fuel heat source from the upstream end of the at least one layer circumscribing the upstream portion of the fuel heat source at or around the downstream end of the fuel heat source . As such, in these embodiments, the fuel heat source may be circumscribed substantially along its length by a combination of at least one additional layer at the downstream end and at least one fiber-reinforced airgel layer at the upstream end. In some embodiments, at least one fiber-reinforced airgel layer and at least one additional layer may be superimposed along the length of the fuel heat source.

[00027] At least one fiber-reinforced airgel layer can be isolated from one or more airflow paths such that, during use, air drawn through the aerosol-generating article along one or more paths of airflow does not directly contact at least one layer of fiber-reinforced airgel.

[00028] In some embodiments, at least one fiber-reinforced airgel layer may be spaced from one or more airflow paths such that air drawn through the aerosol-generating article along one or more airflow paths airflow does not directly contact at least one fiber-reinforced airgel.

[00029] In some embodiments, one or more portions of the at least one fiber-reinforced airgel layer may be covered, coated, or encapsulated in a material substantially impervious to fibers and particles. One or more portions of at least one fiber-reinforced airgel layer that are covered, coated, or encapsulated in a material substantially impermeable to fibers and particles may be located in proximity to air drawn through the aerosol-generating article along one or more airflow paths. The covering, coating or encapsulation can isolate air drawn through the aerosol generating article along one or more air flow paths from the fibers and particles of the at least one layer of fiber reinforced airgel.

[00030] In some embodiments, one or more portions of the at least one layer of fiber-reinforced airgel may be covered in a layer of paper to isolate the at least one layer of fiber-reinforced airgel from one or more airflow paths. The paper layer may be provided on at least one of the inner surface of the at least one fiber-reinforced airgel layer and the outer surface of the at least one fiber-reinforced airgel layer. The paper layer may be provided on both the inner and outer surfaces of at least one fiber-reinforced airgel layer. The paper layer may comprise laminated paper. The paper layer may be collaminated with at least one fiber-reinforced airgel layer. The paper layer may be provided in only a portion of at least one layer of fiber-reinforced airgel that is adjacent to airflow paths.

[00031] At least one fiber-reinforced airgel layer can be substantially resistant to combustion. As used herein, the term "combustible" refers to a material that remains substantially intact during ignition and combustion of the combustible heat source. Providing at least one layer of flame resistant fiber reinforced airgel encircling at least a portion of the length of the fuel heat source can advantageously prevent flames or smoke from being emitted from the layer. This can substantially prevent or inhibit unwanted emissions or odors being released from the layer during the combustion process of the fuel heat source.

[00032] The fuel heat source, the aerosol-forming substrate and at least one fiber-reinforced airgel layer can be configured to substantially prevent and inhibit the temperature of the aerosol-forming substrate from exceeding about 375°C during combustion of the fuel heat source. For example, the combustible heat source, aerosol-forming substrate, and at least one fiber-reinforced airgel layer can be shaped, sized, and arranged to substantially prevent and inhibit the temperature of the aerosol-forming substrate from exceeding about 375°C. during combustion of the fuel heat source. This can preserve the integrity of the aerosol-forming substrate. For example, if the aerosol former substrate comprises one or more aerosol formers, the aerosol formers can undergo pyrolysis above temperatures of about 375°C. At even higher temperatures, for example where the aerosol-forming substrate comprises tobacco, the tobacco may undergo combustion.

[00033] The combustible heat source, the aerosol-forming substrate and at least one fiber-reinforced airgel layer can be configured in such a way that, during the combustion of the combustible heat source, the temperature of the aerosol-forming substrate at 2mm of the proximal face of the aerosol-forming substrate is at least about 100°C for a time period of at least about 6 minutes.

[00034] The fiber-reinforced airgel may comprise less than about 80 weight percent airgel. The fiber-reinforced airgel can comprise less than about 70 weight percent airgel. The fiber-reinforced airgel can comprise greater than about 20 weight percent airgel. The fiber-reinforced airgel can comprise greater than about 30 weight percent airgel. The fiber-reinforced airgel can comprise from about 20 weight percent to about 80 weight percent airgel, or from about 40 weight percent to about 60 weight percent airgel. When the fiber-reinforced airgel comprises a silica airgel, the fiber-reinforced airgel can comprise between about 30 weight percent and about 40 weight percent synthetic amorphous silica. Where the fiber-reinforced airgel comprises a silica airgel, the fiber-reinforced airgel can comprise between about 10 weight percent and about 20 weight percent of methylsilylated silica.

[00035] The fiber-reinforced airgel may comprise at least about 20 weight percent of fibrous material. The fiber-reinforced airgel can comprise at least about 30 weight percent fibrous material. The fiber-reinforced airgel can comprise less than 70 weight percent fibrous material. The fiber-reinforced airgel can comprise less than 60 weight percent fibrous material. The fiber-reinforced airgel can comprise between about 20 weight percent and about 70 weight percent fibrous material, or between about 40 weight percent and about 50 weight percent fibrous material.

[00036] The fiber-reinforced airgel may comprise between about 30 weight percent and about 40 weight percent of synthetic amorphous silica; between about 10 percent by weight and about 80 percent by weight methylsilylated silica; and between about 40 weight percent and about 50 weight percent fibrous material.

[00037] The fiber-reinforced airgel of the present invention may comprise any suitable airgel. Examples of suitable airgels include, but are not limited to, silica airgels, metal oxide airgels, organic and carbon airgels, nanotube airgels, metallic airgels or combinations thereof. Where the airgel is a silica airgel, the airgel may comprise one or more of synthetic amorphous silicas and methylsilylated silica.

[00038] The fiber-reinforced airgel of the present invention may comprise any suitable fibrous material. The fibrous material can comprise one or more of any suitable fibers. For example, any suitable fibers may include, but are not limited to, glass fibers, silica-based fibers, carbon fibers, polymeric fibers, metallic fibers, and ceramic fibers. The fibers can comprise at least one of an organic material and an inorganic material. The fibers can comprise a combination of organic and inorganic materials. The fibrous material can be woven together. The fibrous material may be non-woven. The fibrous material may comprise fiber batting or fiber infill.

[00039] The fiber-reinforced aerosol may comprise a binder.

[00040] The fibrous material may comprise a binder. Binders are used in some fibrous materials to hold the fibrous material together. Providing a binder can also improve the mechanical properties of the fibrous material. For example, a binder can make fibrous material less brittle and more flexible.

[00041] The binder may be a cellulose-derived binder. As used herein, the term "cellulose derivative binder" is used to describe a binder comprising a cellulose derivative. Particularly, the cellulose derivative binder may comprise a cellulose derivative which is formed by adding a particular side group to the cellulose.

[00042] Suitable cellulose derivatives include, but are not limited to, carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEC), hydroxyethylcellulose, cellulose acetate, cellulose ester and cellulose ether. Preferably, the cellulose-derived binder comprises carboxymethylcellulose.

[00043] The binder may comprise one or more organic binders, such as bitumens, glues of animal and vegetable origin and polymers. The binder may comprise one or more inorganic binder materials such as lime, cement, gypsum and liquid gas. Where the binder comprises one or more polymers, the polymers may comprise: acrylic resin, phenolic resin, polyester, epoxy, polyether, PVOH, styrene-based polycarboxylic ether and polyurethane. The binder can comprise one or more of CMC and bentonite. The binder can be an acrylic binder.

[00044] The fiber-reinforced airgel may comprise ceramic fibrous material. The ceramic fibrous material may comprise ceramic fibers.

[00045] Where the fiber reinforced airgel comprises ceramic fibrous material, the ceramic fibrous material may comprise crystalline ceramic materials. The ceramic fibrous material may comprise non-crystalline ceramic materials. The ceramic fibrous material may be amorphous. The ceramic fibrous material can be semicrystalline. The ceramic fibrous material may be crystalline.

[00046] As used herein, the term "ceramic fibrous material" encompasses glasses. As used herein, the term "glass" is used to describe materials that exhibit a glass transition at a glass transition temperature. Typically, the term "glass" is used in this document to describe non-crystalline amorphous solid materials. However, the term "glass" also encompasses materials comprising crystalline components and non-crystalline components. Glass materials comprising both crystalline and non-crystalline components may be referred to as "glass-ceramic" materials.

[00047] The properties of the glass material of the present invention can be determined by the glass forming method. As used herein, the term "glass" encompasses glasses formed by any suitable method. Suitable methods of forming glasses include: quenching; physical vapor deposition; solid-state reactions, including thermochemical and mechanochemical reactions; liquid state reactions such as sol-gel method; irradiation of crystalline solids, such as radiation amorphization; and pressure amorphization (ie, formation under high pressure action).

[00048] In some embodiments, the ceramic fibrous material may comprise a glass. The ceramic fibrous material may comprise glass fibers. The glass fibers may comprise a glass-ceramic material. The ceramic fibrous material may comprise continuous filament glass fibers.

[00049] In some embodiments, the ceramic fibrous material does not comprise a glass. In other words, the ceramic fibrous material can comprise any ceramic materials other than glasses. The ceramic fibrous material may not be a glass material. The ceramic fibrous material may not comprise glass fibers. In these embodiments, the ceramic fibrous material typically comprises crystalline ceramic materials.

[00050] In some embodiments, the fibrous material may comprise biosoluble fibers. As used herein, the term "biosoluble" is used to describe a material that is soluble in a biological system, such as a biological system in the human body. The biosolubility of a material in a particular biological system can differ significantly from the material's solubility in water. As used herein, a substance can be considered biosoluble if at least 0.1 g of such substance dissolves in 100 ml of the biological system solvent. Similarly, a substance can be considered bioinsoluble if less than 0.1 g of the material dissolves in 100 ml of the biological system solvent. Typically, a biosoluble fiber of the present invention is soluble in a user's respiratory system upon inhalation of the fiber. In other words, a biosoluble fiber of the present invention typically dissolves in a user's respiratory system upon inhaling the fiber. The biosoluble fibers of the present invention may be soluble in a person's alveolar environment.

[00051] The biosoluble material may be any suitable biosoluble material. Suitable biosoluble materials include alkaline earth silicate wools and high alumina, low silica wools.

[00052] In some embodiments of the invention, the fiber-reinforced airgel may comprise about 100 percent by weight alkaline earth silicate wool.

[00053] The fiber-reinforced airgel may comprise any other suitable reinforcing material. For example, the fiber-reinforced airgel can comprise polymer fibers such as polyamides and polyimides. The fiber-reinforced airgel can be further reinforced by additional means, such as particulate reinforcement. For example, fiber reinforced airgel can be reinforced with carbon black particles. The fiber-reinforced airgel can additionally include any other suitable constituents, including, but not limited to, titanium dioxide, aluminum trihydrate, and pigments that can include iron and manganese.

[00054] Suitable fiber-reinforced aerogels include Pyrogel® XT-E and Pyrogel® XT-F, both produced by Aspen Aerogels®.

[00055] At least one fiber-reinforced airgel layer may be of any suitable thickness. Generally, at least one fiber-reinforced airgel layer is a thin layer. The thickness of at least one fiber-reinforced airgel layer can be at least about 0.25 millimeters or at least about 0.5 millimeters. The thickness of the at least one fiber-reinforced airgel layer can be less than about 10 millimeters or less than about 5 millimeters. The at least one fiber-reinforced airgel layer can have a thickness of between about 0.25 millimeters and about 10 millimeters or between about 0.5 millimeters and about 5 millimeters.

[00056] An aerosol-generating article according to the present invention comprises an aerosol-forming substrate. As used herein, the term "aerosol-forming substrate" is used to describe a substrate capable of releasing volatile compounds upon heating, which can form an aerosol. Aerosols generated from aerosol-forming substrates of aerosol-generating articles according to the invention may be visible or invisible and may include vapors (e.g. fine particles of substances, which are in a gaseous state, which are generally liquid or solid at room temperature) as well as liquid droplets or condensed vapors.

[00057] The aerosol-forming substrate may be solid. The aerosol-forming substrate may be solid at room temperature.

[00058] The aerosol-forming substrate may comprise at least one aerosol former and at least one material capable of emitting volatile compounds in response to heating.

[00059] The at least one aerosol former can be any suitable known compound or mixture which, in use, facilitates the formation of a dense and stable aerosol and which is substantially resistant to thermal degradation at the operating temperature of the aerosol generating article. Suitable aerosol formers are well known in the art and include, for example, polyhydric alcohols, esters of polyhydric alcohols such as glycerol mono-, di- or triacetate and aliphatic esters of mono-, di- or polycarboxylic acids , such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Exemplary aerosol formers for use in aerosol generating articles according to the invention are polyhydric alcohols or mixtures thereof, such as a triethylene glycol, 1,3-butanediol and glycerin.

[00060] The material capable of emitting the volatile compounds in response to heating may be a filler of plant-based material, for example, a filler of homogenized plant-based material. For example, the aerosol-forming substrate can comprise one or more plant-derived materials, including, but not limited to: tobacco; tea, for example green tea; mint; laurel; eucalyptus; basil; saves; verbena; and tarragon. The herbal material can comprise additives, including but not limited to humectants, flavors, binders and mixtures thereof. The herbal material may consist essentially of tobacco material, optionally homogenized tobacco material.

[00061] Aerosol-generating articles according to the invention may comprise aerosol-forming substrates comprising nicotine. For example, aerosol generating articles according to the invention comprise aerosol forming substrates comprising tobacco.

[00062] The aerosol-forming substrate may be circumscribed by a filter plug housing.

[00063] An aerosol-generating article according to the present invention comprises a combustible heat source arranged to heat an aerosol-forming substrate and isolated from one or more airflow paths.

[00064] The combustible heat source may comprise a body of combustible material. The body of combustible material may have a substantially constant diameter. The body of combustible material may have a constant diameter along its length. This can advantageously simplify the processes involved in manufacturing the combustible heat source and aerosol generating article. In some embodiments, the body of combustible material may form a circularly cylindrical body having a substantially constant diameter along its length.

[00065] The combustible heat source may be a carbonaceous heat source. As used herein, the term "carbonaceous" is used to describe a combustible heat source comprising carbon. Preferably, combustible carbonaceous heat sources for use in aerosol generating articles according to the invention have a carbon content of at least about 35 percent, more preferably at least about 40 percent, most preferably at least about 40 percent. about 45 percent by dry weight of the fuel heat source 30.

[00066] The combustible heat source according to the present invention may be a combustible carbon-based heat source. As used herein, the term "carbon-based heat source" is used to describe a heat source comprised primarily of carbon.

[00067] Carbon-based combustible heat sources for use in aerosol generating articles according to the invention may have a carbon content of at least about 50 percent, preferably at least about 60 percent, more preferably at least about 70 percent, more preferably at least about 80 percent by dry weight of the carbon-based fuel heat source.

[00068] The fuel heat source of the present invention is isolated from one or more airflow paths through the aerosol generating article. As used herein, the term "air flow path" is used to describe a route along which air can be drawn through the aerosol generating article for inhalation by a user. As used herein, the terms "upstream" and "downstream" are used to describe directions and relative positions of components of the aerosol-generating article with respect to the direction that air flows through one or more airflow paths when a user brings the air into the aerosol generating item.

[00069] The isolation of the combustible heat source from one or more air flow paths of the aerosol generating article can prevent or substantially inhibit the activation of combustion of the combustible heat source during puffing by a user. This can substantially prevent or inhibit spikes in the temperature of the aerosol-forming substrate during a user's puff on the aerosol-generating article. This can substantially prevent or inhibit combustion or pyrolysis of the aerosol-forming substrate under heavy puff regimes. This can substantially prevent or inhibit changes in the composition of the aerosol generated by the aerosol generating article due to a user puff regimen.

[00070] Isolation of the combustible heat source from one or more air flow paths can also substantially prevent or inhibit combustion and decomposition products and other materials formed during ignition and combustion of the combustible heat source, from entering the air drawn through the aerosol-generating article along one or more airflow paths.

[00071] The isolated combustible heat source of the present invention may comprise a blind heat source. As used herein, the term "blind" is used to describe a combustible heat source in which air drawn through the aerosol generating article for inhalation by a user does not pass through an airflow channel along the source of combustible heat. As such, heat transfer between the blind fuel heat source and the aerosol-forming substrate occurs predominantly by conductive heat transfer.

[00072] By not providing airflow channels through the fuel heat source, convective heat transfer between the fuel heat source and the aerosol-forming substrate is reduced or minimized. Reducing convective heat transfer between the fuel heat source and the aerosol-forming substrate can substantially prevent or inhibit spikes in the temperature of the aerosol-forming substrate during puffing by a user. This can substantially prevent or inhibit combustion or pyrolysis of the aerosol-forming substrate under heavy puff regimes. This can substantially prevent or inhibit changes in the composition of the aerosol generated by the aerosol generating article due to a user puff regimen. It can also substantially prevent or inhibit combustion and decomposition products, and other materials formed during ignition and combustion of the combustible heat source, from entering air drawn through the aerosol generating article along one or more flow paths. air.

[00073] The isolated combustible heat source of the present invention may comprise a non-blind heat source. As used herein, the term "non-blind" is used to describe a heat source in which air drawn through the aerosol generating article for inhalation to a user passes through one or more airflow channels along the source. of heat. As such, heat transfer between the non-blind combustible heat source and the aerosol-forming substrate can occur both by conductive heat transfer and by convective heat transfer along one or more airflow channels.

[00074] As used herein, the term "airflow channel" is used to describe a channel extending along the length of a combustible heat source through which air can be drawn downstream for inhalation by a user. As such, the aerosol generating article of the present invention may not comprise one or more airflow channels.

[00075] One or more non-combustible, substantially air-impermeable barriers between the combustible heat source and the aerosol-forming substrate may comprise a barrier that abuts at one or both proximal ends of the combustible heat source and a distal end of the aerosol-forming substrate. The first barrier can facilitate isolation of the combustible heat source from one or more airflow paths of the aerosol generating article. The first barrier can reduce the maximum temperature to which the aerosol-forming substrate is exposed during ignition or combustion of the combustible heat source, and can substantially prevent or inhibit thermal degradation or combustion of the aerosol-forming substrate during use of the generating article. of aerosol.

[00076] As used herein, the term "non-combustible" is used to describe a material that is substantially non-combustible at temperatures reached by the combustible heat source during combustion or ignition thereof.

[00077] As used herein, the term "air tight" is used to describe a material that substantially prevents or inhibits the passage of air therethrough.

[00078] The first barrier can be adhered or otherwise attached to one or more of the proximal ends of the fuel heat source at the distal end of the aerosol-forming substrate.

[00079] The first barrier may comprise a first barrier coating on a proximal face of the fuel heat source. In such embodiments, the first barrier comprises a first barrier coating on at least substantially all of the proximal face of the fuel heat source. The first barrier may comprise a first barrier coating provided across the proximal face of the fuel heat source. The first barrier coating can be formed and applied to the proximal face of the fuel heat source by any method, such as the methods described in WO-A1-2013120855.

[00080] Depending on the desired characteristics and performance of the aerosol generating article, the first barrier can have a low thermal conductivity or a high thermal conductivity. In certain embodiments, the first barrier can have a thermal conductivity of between about 0.1 W/m.K and about 200 W/m.K.

[00081] The thickness of the first barrier can be suitably adjusted to achieve good aerosol generation performance. In certain embodiments, the first barrier can have a thickness of between about 10 microns and about 500 microns.

[00082] The first barrier may be formed from one or more suitable materials that are substantially thermally stable and non-combustible at the temperatures reached by the combustible heat source during ignition and combustion. Suitable materials are known in the art and include, but are not limited to, clays (such as, for example, bentonite and kaolinite), glasses, minerals, ceramic materials, resins, metals and combinations thereof.

[00083] The materials from which the first barrier can be formed include clays and glasses. More materials from which the first barrier can be formed include copper, aluminum, stainless steel, alloys, alumina (Al2O3), mineral resins and glues.

[00084] Where the first barrier comprises a metal or an alloy, such as copper, aluminum, stainless steel, the first barrier coating can advantageously act as a thermal bond between the combustible heat source and the heat-forming substrate aerosol. This can enhance conductive heat transfer from the fuel heat source to the aerosol forming substrate.

[00085] The aerosol generating article may further comprise one or more air inlets downstream from a proximal end of the fuel heat source. In some embodiments, one or more air ports are between the proximal end of the fuel heat source and a proximal end of the aerosol generating article. One or more air inlets may be arranged so that air can be drawn into one or more air flow paths of the aerosol generating article, through the one or more air inlets, without being drawn in through the combustible heat source. . This can prevent or inhibit spikes in the temperature of the aerosol-forming substrate during puffs by a user.

[00086] One or more air inlets may comprise any suitable air inlets by means of which air can be drawn into the aerosol generating article. For example, suitable air intakes include holes, slots, slots or other openings. The number, shape, size and arrangement of air inlets can be adjusted accordingly to achieve good aerosol generating performance.

[00087] One or more air inlets may be disposed anywhere between the proximal end of the fuel heat source and the proximal end of the aerosol generating article. One or more air ports may be disposed in the aerosol-forming substrate. One or more air ports may be disposed between a distal end of the aerosol-forming substrate and a proximal end of the aerosol-forming substrate. If one or more air inlets are disposed in the aerosol-forming substrate and the aerosol-forming substrate comprises a filter plug housing, the filter plug housing may be provided with one or more openings to allow air into the aerosol-forming substrate. aerosol. One or more openings can be slots, slots or other suitable openings through which air can be drawn into the aerosol-forming substrate. The number, shape, size and arrangement of the air openings can be suitably adjusted to achieve good aerosol generating performance.

[00088] The fuel heat source may comprise one or more airflow channels. In other words, the combustible heat source can be a non-blind heat source. One or more airflow channels may extend the length of the fuel heat source. One or more airflow channels may be integral with one or more airflow paths of the aerosol generating article.

[00089] If the combustible heat source comprises one or more air flow channels in the aerosol generating article, one or more substantially air impermeable non-combustible barriers between the combustible heat source and the aerosol-forming substrate may further comprise a second barrier between the fuel heat source and one or more air flow channels of the fuel heat source.

[00090] The second barrier can facilitate isolation of the combustible heat source from one or more airflow paths of the aerosol generating article. The second barrier can reduce the maximum temperature to which the aerosol-forming substrate is exposed during ignition or combustion of the combustible heat source and thus helps to prevent or reduce thermal degradation or combustion of the aerosol-forming substrate during the use of the aerosol generating article.

[00091] The second barrier may be adhered or otherwise affixed to the combustible heat source.

[00092] The second barrier may comprise a second barrier coating provided on an inner surface of one or more airflow channels. The second barrier may comprise a second barrier coating provided over at least substantially all of the inner surface of one or more airflow channels. The second barrier may comprise a second barrier coating provided over the entire inner surface of one or more airflow channels.

[00093] The second barrier coating can be provided by inserting a liner within one or more airflow channels. For example, if one or more airflow paths comprise one or more airflow channels extending through the interior of the combustible heat source, a substantially air-impermeable non-combustible hollow tube can be inserted into one of the one or more airflow channels.

[00094] The second barrier can advantageously and substantially prevent or inhibit the products of combustion and decomposition, formed during the ignition and combustion of the combustible heat source of the aerosol generating articles, according to the invention, from entering the Air drawn downstream along one or more airflow channels.

[00095] Depending on the performance and desired characteristics of the aerosol generating article, the second barrier can have low thermal conductivity or high thermal conductivity. The second barrier can have a low thermal conductivity.

[00096] The thickness of the second barrier can be adjusted appropriately to obtain good aerosol generation performance. In certain embodiments, the second barrier can be between about 30 microns and about 200 microns thick. In one embodiment, the second barrier has a thickness between about 30 microns and about 100 microns.

[00097] The second barrier may be formed from one or more suitable materials that are substantially thermally stable and non-combustible at the temperatures reached by the combustible heat source during ignition and combustion. Suitable materials are known in the art and include, but are not limited to, for example: clays; metallic oxides, such as iron oxide, alumina, titania, silica, silica-alumina, zirconia and ceria; zeolites; zirconium phosphate; and other ceramic materials or combinations thereof.

[00098] Materials from which the second barrier can be formed include clays, glasses, aluminum, iron oxide and combinations thereof. If desired, catalytic ingredients, such as ingredients that promote the oxidation of carbon monoxide to carbon dioxide, can be incorporated into the second barrier. Suitable catalytic ingredients include but are not limited to, for example, platinum, palladium, transition metals and their oxides.

[00099] If the aerosol-generating articles according to the invention comprise a first barrier between a downstream end of the fuel heat source and an upstream end of the aerosol-forming substrate and a second barrier between the fuel heat source and one or more airflow channels along the fuel heat source, the second barrier may be formed from the same or different material or materials as the first barrier.

[000100] If the second barrier comprises a second barrier coating provided on an inner surface of one or more airflow channels, the second barrier coating can be applied to the inner surface of one or more airflow channels by any suitable method, such as the methods described in USA-5,040,551 and WO-A1-2013120855.

[000101] The aerosol-generating article may further comprise one or more additional layers that surround at least a proximal portion of the combustible heat source and a distal portion of the aerosol-forming substrate. One or more additional layers may comprise at least one of: a heat conducting element for transferring heat from the combustible heat source to the aerosol forming substrate; and a layer of cigarette paper.

[000102] The heat conducting element can circumscribe only a distal part of the aerosol-forming substrate. The heat conducting element may substantially circumscribe the length of the aerosol forming substrate. The heat conducting element may be in direct contact with at least one of the combustible heat source and the aerosol forming substrate. The heat conducting element may not be in direct contact with either the combustible heat source and the aerosol forming substrate.

[000103] The heat-conducting element can provide a thermal link between the combustible heat source and the aerosol-forming substrate. The heat conducting element may be substantially resistant to combustion.

[000104] Suitable heat conducting elements may include: sheet metal casings or metal alloy foil casings. Metal foil wrappers can include: aluminum foil wrappers, steel foil wrappers, iron foil wrappers, and copper foil wrappers. The heat conducting element may comprise an aluminum tube.

[000105] The proximal portion of the fuel heat source circumscribed by the heat conducting element may be between about 2 millimeters and about 8 millimeters long, or between about 3 millimeters and about 5 millimeters long.

[000106] The distal portion of the combustible heat source not surrounded by the heat conducting element may be between about 4 millimeters and about 15 millimeters long, or between about 4 millimeters and about 8 millimeters long.

[000107] The cigarette paper layer may surround at least a proximal portion of the fuel heat source, the length of the aerosol-forming substrate and any other components of the aerosol-generating article disposed proximally to the aerosol-forming substrate. The cigarette paper layer may substantially circumscribe the length of the fuel heat source. If the cigarette paper layer substantially circumscribes the length of the fuel heat source, the cigarette paper layer may be provided with ventilation, such as perforations, holes or slits, in the fuel heat source to allow air to pass through. from the cigarette paper layer to the fuel heat source. The number, shape, size and location of the air openings can be adjusted accordingly to achieve good aerosol generating performance. The cigarette paper layer may be tightly wrapped around the combustible heat source and aerosol-forming substrate so that the cigarette paper layer grips and secures the combustible heat source and aerosol-forming substrate when the aerosol-generating article is mounted.

[000108] At least one fiber-reinforced airgel layer may be a radially outer layer. If the aerosol generating article comprises one or more additional layers, the radially outer layer of fiber reinforced airgel may overlay at least a portion of the one or more additional layers. In other words, one or more additional layers can be disposed between the fuel heat source and at least one fiber-reinforced airgel layer. For example, if the aerosol generating article comprises an additional layer comprising a heat conducting element, the heat conducting element may be a radially inner layer and the at least one layer of fiber reinforced airgel may be a radially outer layer, circumscribing at at least a portion of the heat conducting element.

[000109] In this document, the terms "radially external" and "radially internal" are used to indicate the relative distances of the components of the aerosol-generating article from the longitudinal axis of the aerosol-generating article. In this document, the term "radial" is used to describe the direction perpendicular to the longitudinal axis of the aerosol-generating article that extends in the direction between the proximal end and the distal end of the aerosol-generating article.

[000110] One or more additional layers may be radially outer layers. One or more additional layers may overlay at least a portion of the at least one fiber-reinforced airgel layer.

[000111] At least one fiber-reinforced airgel layer can be attached or bonded to one or more components or parts of the aerosol generating article. At least one layer of fiber reinforced airgel may be attached to any suitable component of the aerosol generating article. For example, at least one fiber-reinforced airgel layer can be attached to at least one of a combustible heat source, aerosol-forming substrate, and one or more additional layers. At least one layer of fiber reinforced airgel may be attached to one or more components of the aerosol generating article by any suitable means. At least one fiber-reinforced airgel layer can be attached using an adhesive. Suitable adhesives may have high temperature resistance, such as silicate glue. If the one or more additional layers are radially outer layers, the one or more additional layers may be tightly wrapped around at least a portion of the at least one fiber-reinforced airgel layer.

[000112] In some embodiments, at least one fiber-reinforced airgel layer may be an integral part of the fuel heat source. In this document, the term "integrant" is used to describe a layer that is in direct contact with the fuel heat source and bonded to the fuel heat source without the aid of an extrinsic adhesive or other intermediate connecting material.

[000113] In some embodiments, at least one fiber-reinforced airgel layer can be formed by a strip of fiber-reinforced airgel with opposite ends. The fiber-reinforced airgel strip can be wrapped around the fuel heat source so that opposite ends of the strip overlap. The overlapping opposite ends of the strip can be secured using an adhesive or any other suitable means. This can secure at least one layer of fiber-reinforced airgel to the fuel heat source.

[000114] In some embodiments, an intermediate layer can be provided between at least one fiber-reinforced airgel layer and at least one combustible heat source, aerosol-forming substrate and one or more additional layers. The intermediate layer may be adjacent to at least one fiber-reinforced airgel layer. The intermediate layer may be in contact with at least one layer of fiber-reinforced airgel. The intermediate layer may be disposed radially within at least one fiber-reinforced airgel layer.

[000115] The intermediate layer can be an adhesive layer. The adhesive layer can comprise any suitable adhesive. Suitable adhesives may have high temperature resistance, such as silicate glue. The adhesive layer may be disposed between the at least one fiber-reinforced airgel layer and the fuel heat source and may bond the at least one fiber-reinforced airgel layer to the fuel heat source. The adhesive layer may be disposed between at least one fiber-reinforced airgel layer and one or more additional layers and may bond at least one fiber-reinforced airgel layer to one or more additional layers. The adhesive layer may be disposed between at least one fiber-reinforced airgel layer and the aerosol-forming substrate and may bond the at least one fiber-reinforced airgel layer to the aerosol-forming substrate.

[000116] In some embodiments, at least one fiber-reinforced airgel layer can be formed by a strip of fiber-reinforced airgel with opposite ends. The fiber-reinforced airgel strip can be wrapped around the fuel heat source so that opposite ends of the strip abut without overlapping. An adhesive layer may be provided on the side of the strip facing the fuel heat source, at least at opposite ends of the strip. The adhesive layer may secure the fiber-reinforced airgel strip to the fuel heat source, at least at opposite ends of the strip.

[000117] The aerosol-generating article may comprise a heat-conducting member disposed between the combustible heat source and the aerosol-forming substrate. The heat conducting member may be the first barrier, described above. The aerosol generating article may comprise a heat conducting member and a first barrier. The heat conducting member may comprise material similar to the heat conducting member. The aerosol generating article may comprise a heat conducting member and a heat conducting member. The provision of at least one heat conducting member and the heat conducting member can facilitate conductive heat transfer between the combustible heat source and the aerosol forming substrate.

[000118] The aerosol generating article may further comprise any other suitable components. For example, the aerosol generating article can comprise at least one of: a transfer element; an aerosol cooling element; a spacer element; and a mouthpiece. One or more additional components may be disposed coaxially with the fuel heat source and the aerosol-forming substrate. One or more additional components may be disposed proximally to the aerosol-forming substrate. One or more additional components can be arranged in any suitable order. The aerosol-generating article may further comprise: a transfer member adjacent the proximal end of the aerosol-forming substrate; an aerosol cooling element adjacent the proximal end of the transfer element; a spacer element adjacent the proximal end of the aerosol cooling element; and a nozzle adjacent the proximal end of the spacer element.

[000119] In this document, the terms "proximal" and "distal" are used to describe the relative positions of components, or portions of components, of aerosol generating articles, according to the invention. The proximal end of an aerosol-generating article component is the end of that component that is closest to the mouth end of the aerosol-generating article and the distal end of an aerosol-generating article component is the end of the component that is farthest away. from the mouth end of the aerosol generating article. Typically, the fuel heat source is disposed at the distal end of the aerosol generating article.

[000120] According to a second aspect of the present invention, there is provided a method of forming an aerosol generating article, according to the first aspect of the invention. The method comprises: arranging a fuel heat source to heat an aerosol-forming substrate; provide one or more airflow paths along which air can be drawn through the aerosol-generating article for inhalation by a user, isolating the combustible heat source from one or more airflow paths so that, during In use, air drawn through the aerosol-generating article along one or more airflow paths does not come into direct contact with the combustible heat source; and surrounding at least part of the length of the fuel heat source with at least one layer of fiber-reinforced airgel.

[000121] In some embodiments, the step of circumscribing at least a portion of the length of the fuel heat source with at least one layer of fiber-reinforced airgel may comprise: providing a strip of fiber-reinforced airgel with opposite ends; wrapping the strip around the fuel heat source such that the fuel heat source is surrounded by at least one layer of fiber-reinforced airgel; overlap opposite ends of the strip; and bringing the overlapping ends together to provide at least one fiber-reinforced airgel layer to the fuel heat source.

[000122] The overlapping ends of the fiber-reinforced airgel strip can be joined using any suitable means. For example, the overlapping ends of the fiber-reinforced airgel strip can be joined together using adhesive. Suitable adhesives should have high temperature resistance and include silica glue.

[000123] In some embodiments, the step of circumscribing at least a portion of the length of the fuel heat source with at least one layer of fiber-reinforced airgel may comprise: providing a strip of gel-reinforced airgel with opposite ends; applying a layer of adhesive to one side of the strip at least at each opposite end; lay the strip with the adhesive layer facing the fuel heat source; wrapping the strip around the fuel heat source such that at least a portion of the length of the fuel heat source is circumscribed by at least one layer of fiber-reinforced airgel; abutting the opposite ends of the strip without overlapping the opposite ends; and bonding the combustible heat source strip with the adhesive layer.

[000124] In some embodiments, at least one fiber-reinforced airgel layer may be laminated with an additional layer, such as a cigarette paper layer. The at least one fiber-reinforced airgel layer may be laminated with the additional layer before the at least one fiber-reinforced airgel layer is applied to the fuel heat source. A laminated paper strip comprising at least one fiber-reinforced airgel layer and the additional layer may be enveloped in the fuel heat source in the same manner as the fiber-reinforced airgel strip. In some embodiments, the collaminated paper may be arranged so that at least one fiber-reinforced airgel layer faces the fuel heat source. In other words, at least one fiber-reinforced airgel layer can be disposed radially within the additional layer. In some embodiments, the laminated paper may be arranged so that the additional layer faces the fuel heat source.

[000125] The invention will be described below, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic representation of a first embodiment of an aerosol generating article, according to the present invention, comprising a blind combustible heat source; Figure 2 shows the temperature profile of the aerosol generating article of Figure 1 in a first position; Figure 3 shows the temperature profile of the aerosol generating article of Figure 1 in a second position; Figure 4 shows the temperature profile of the aerosol generating article of Figure 1 in a third position; and Figure 5 shows a schematic representation of a second embodiment of an aerosol generating article, in accordance with the present invention, comprising a non-blind combustible heat source.

[000126] Figure 1 shows a schematic representation of an aerosol generating article 2. The aerosol generating article 2 comprises a fuel heat source 3. The fuel heat source 3 comprises a substantially circular cylindrical body of carbonaceous material, with a length of about 10 millimeters. Combustible heat source 3 is a blind heat source. In other words, the combustible heat source 3 does not comprise any air channel extending through it.

[000127] The aerosol-generating article 2 further comprises an aerosol-forming substrate 4. An aerosol-forming substrate 4 is arranged at a proximal end of the fuel heat source 3. The aerosol-forming substrate 4 comprises a substantially circular cylindrical plug of tobacco material 18 circumscribed by filter plug housing 19.

[000128] A first substantially air-impermeable non-combustible barrier 6 is arranged between the proximal end of the combustible heat source 3 and a distal end of the aerosol-forming substrate 4. The first barrier 6 comprises an aluminum foil disc. The first barrier 6 also forms a heat conducting member between the fuel heat source 3 and the aerosol forming substrate 4 to conduct heat from the proximal face of the fuel heat source 3 to the distal face of the aerosol forming substrate 4.

[000129] A heat-conducting element 9 surrounds a proximal portion of the fuel heat source 3 and a distal portion of the aerosol-forming substrate 4. The heat-conducting element 9 comprises an aluminum foil tube. The heat conducting element 9 is in direct contact with the proximal portion of the combustible heat source 3 and the filter plug housing 19 of the aerosol forming substrate 4.

[000130] The aerosol-generating article 2 may further comprise various other components arranged proximally to the aerosol-forming substrate 4, including: a transfer element 11 arranged at the proximal end of the aerosol-forming substrate 4; an aerosol cooling element 12 disposed at the proximal end of the transfer element 11; a spacer element 13 disposed at the proximal end of the aerosol cooling element 11; and a nozzle 10 disposed at a proximal end of the spacer element 13.

[000131] The components of the aerosol generating article 2 are wrapped in a layer of cigarette paper 7. The layer of cigarette paper 7 circumscribes the heat conducting element 9, but does not extend beyond the distal end of the heat conducting element 9, on the distal portion of the fuel heat source 3.

[000132] According to the present invention, the aerosol generating article 2 further comprises a fiber-reinforced airgel layer 5. The fiber-reinforced airgel layer 5 substantially circumscribes the length of the fuel heat source 3 and a distal portion of the cigarette paper layer 7, the heat conducting element 9 and the aerosol forming substrate 4. In other words, the fiber reinforced airgel layer 5 is the radially outer layer at the distal end of the aerosol generating article 2.

[000133] The fiber reinforced airgel layer 5 comprises a silica airgel and a fibrous material comprising continuous filament glass fibers. The fiber-reinforced airgel comprises about 35 weight percent synthetic amorphous silica, about 15 weight percent methylsilyl silica, and about 45 weight percent continuous filament glass fibers.

[000134] A plurality of air inlets 8 are arranged in the aerosol-forming substrate 4 to allow ambient air to be drawn into the aerosol-generating article 2. The air inlets 8 comprise a plurality of perforations through the paper layer of cigarette 7 and the underlying layer of plug wrapper 19 that surrounds the aerosol-forming substrate 4. The air inlets 8 are disposed between the distal face and the proximal face of the aerosol-forming substrate 4.

[000135] When a user brings the mouthpiece 10 of the aerosol-generating article 2, ambient air can be drawn into the aerosol-generating article 2 through the air inlets 8. The air drawn into the aerosol-generating article 2 can flow to the along an air flow path of the aerosol generating article 2, from the air inlets 8, through the aerosol forming substrate 4, the transfer element 11, the cooling element 12 and the spacer element 13 to the mouthpiece 10, and the mouthpiece 10 to the user for inhalation. The general direction of air flow through the aerosol generating article 2 is indicated by the arrows.

[000136] During use, a user can ignite the combustible heat source 3 by exposing the combustible heat source 3 to an external heat source, such as a lighter. The combustible heat source 3 can ignite and burn and heat can be transferred from the combustible heat source 3 to the aerosol-forming substrate 4 via conduction through the heat conducting member 6 and the heat conducting element 9. The volatile components of the heated aerosol-forming substrate 4 can be vaporized. A user can puff through the mouthpiece 10 of the aerosol-generating article 2 by drawing ambient air into the air flow path of the aerosol-generating article 2 through the air inlets 8. Vapor from the heated aerosol-forming substrate 4 can be drawn into the Air is drawn through the aerosol-forming substrate 4 and may be drawn with the air towards the nozzle 10. As the vapor is drawn into the nozzle 10, the vapor may be cooled to form an aerosol. The aerosol can be drawn into mouthpiece 10 and dispensed to the user for inhalation.

[000137] It will be appreciated that the first substantially air-impermeable barrier 6 inhibits air being drawn through the fuel heat source 3 and into the aerosol-forming substrate 4. Thus, the first barrier 6 substantially isolates the flow path of air from the aerosol generating article 2 from the fuel heat source 3.

[000138] In this embodiment, the fiber-reinforced airgel layer 5 extends over the smaller portion of the distal end of the aerosol-forming substrate 4. Thus, the fiber-reinforced airgel layer 5 is spaced away from the air inlets 8. This spacing substantially insulates the fiber-reinforced airgel layer 5 from the air inlets 8, so that air drawn through the airflow path of the aerosol-generating article 2 does not come into contact with the fiber-reinforced airgel layer 5.

[000139] It will be appreciated that, in some embodiments, the fiber-reinforced airgel layer may be close to the air intakes. In these embodiments, the portions of the fiber-reinforced airgel layer that are close to the air inlets may be coated with a material substantially impermeable to fibers and particles. This can substantially insulate the portions of the fiber-reinforced airgel layer that are close to the air inlets, so that air drawn through the airflow path of the aerosol-generating article does not come into contact with the fiber-reinforced airgel layer. fiber.

[000140] Experimental data were collected to determine the temperature of fuel heat sources and aerosol-forming substrates of various aerosol-generating articles similar to aerosol-generating article 2 shown in Figure 1 by the period of combustion of the fuel heat source. Each aerosol generating article tested contained a different layer of material that substantially circumscribed the length of the fuel heat source. In particular, experimental data were collected for aerosol generating articles comprising an unreinforced airgel layer (AeroZero® produced by Blueshift International Materials, Inc.) that substantially circumscribes the length of the fuel heat source, a fiber reinforced airgel layer (Pyrogel® XT-F manufactured by AspenAerogels, Inc.) that substantially circumscribes the length of the combustible heat source and no layer of material that substantially circumscribes the length of the combustible heat source. Figures 2-4 show plots of experimental temperature measurements over time at three different locations of various aerosol generating articles.

[000141] Figure 2 shows the temperature measured at a position 2 millimeters from the distal end of the fuel heat source, which corresponds to position T1 shown in Figure 1. In other words, Figure 2 shows the temperature at the distal end of the fuel source combustible heat.

[000142] Figure 3 shows the temperature measured at a position 5 millimeters from the distal end of the fuel heat source, which corresponds to position T2 shown in Figure 1. In other words, Figure 3 shows the temperature approximately in the middle of the length of the fuel heat source.

[000143] Figure 4 shows the temperature measured at a position 11 millimeters from the distal end of the fuel heat source, which corresponds to position T3 shown in Figure 1. In other words, Figure 4 shows the temperature at the distal end of the forming substrate of aerosol.

[000144] All temperature profiles were measured using electronic temperature probes that were inserted approximately 2 millimeters deep into the relevant components of the aerosol generating articles.

[000145] In Figures 2, 3 and 4 the "AeroZero" line, marked as 20, shows the temperature profile of the aerosol generating article with an unreinforced airgel layer substantially circumscribing the length of the fuel heat source.

[000146] In Figures 2, 3 and 4, the line "Pyrogel XTF", marked as 21, shows the temperature profile of the aerosol generating article with a layer of fiber-reinforced airgel substantially circumscribing the length of the fuel heat source, according to the present invention.

[000147] In Figures 2, 3 and 4 the line "SMAR", marked as 22, shows the temperature profile of the aerosol generating article without any layer of material substantially circumscribing the length of the fuel heat source.

[000148] It is desirable that aerosol-generating articles with a layer of material substantially circumscribing the length of the aerosol-generating article have substantially similar temperature profiles or that exceed the temperature profile of the aerosol-generating article without any layer of material substantially circumscribing the length of the combustible heat source, marked 22. This indicates that the layer of material does not substantially inhibit combustion of the combustible heat source.

[000149] As shown in Figures 2, 3 and 4, the temperature 20 of the aerosol-generating article with the unreinforced airgel layer substantially circumscribing the length of the fuel heat source is below the temperature 22 of the aerosol-generating article without any layer of material substantially circumscribing the length of the fuel heat source at all three locations of the aerosol generating article throughout the entire combustion time of the fuel heat source.

[000150] Surprisingly, as shown in Figures 2, 3 and 4, the temperature 21 of the aerosol generating article with the fiber-reinforced airgel layer substantially circumscribing the length of the fuel heat source is substantially similar to the temperature 22 of the aerosol generating article aerosol with no layer of material substantially circumscribing the length of the fuel heat source at all three locations on the aerosol generating article during most of the combustion time of the fuel heat source. Furthermore, the temperature 21 of the aerosol generating article with the layer of fiber reinforced airgel substantially circumscribing the length of the fuel heat source actually exceeds the temperature 22 of the aerosol generating article with no layer of material substantially circumscribing the length. of the fuel heat source at all three aerosol generating article locations at the end of the aerosol generating experiment.

[000151] This surprising result indicates that the provision of at least one fiber-reinforced airgel layer substantially circumscribing the length of the fuel heat source does not advantageously and substantially prevent the combustion of the fuel heat source. Indeed, the provision of the fiber reinforced airgel layer can increase the temperature of the fuel heat source towards the end of the combustion time of the fuel heat source, which can prolong the period of time that the aerosol is generated by the fuel generating article. aerosol and thus prolong the aerosol generation experience for the user.

[000152] The aerosol generating articles, according to the invention, were tested by observing their effect when placing them on Whatmann papers after the heat source was ignited. For example, aerosol generating articles were conditioned for 24 hours at about 23°C ± 3°C and 55%±5% relative humidity. The conditioned aerosol generating articles were lit using an electric lighter and allowed to burn for a period of 3 minutes. After 3 minutes, the aerosol generating articles were placed on a stack of Whatmann papers for a period of 8 minutes. After 8 minutes, the Whatmann papers were inspected. It was observed that the aerosol generating article with the fiber reinforced airgel layer substantially circumscribing the length of the fuel heat source did not produce a hole in the Whatmann papers and produced a small dark area in the top paper. This result shows that having the fiber-reinforced airgel layer substantially circumscribing the length of the fuel heat source reduces the surface temperature close to the heat source.

[000153] A schematic representation of a second embodiment of an aerosol-generating article according to the present invention is shown in Figure 5. The aerosol-generating article 102 is substantially similar to the aerosol-generating article 2 shown in Figure 1. The article The aerosol generator 102 comprises a combustible heat source 103, an aerosol-forming substrate 104, a fiber-reinforced airgel layer 105, and a cigarette paper layer 107 disposed similarly to corresponding components of the aerosol-generating article 102 shown in Figure 1 However, the fuel heat source 103 is a non-blind heat source. The non-blind heat source 103 comprises an annular body 115 of carbonaceous material with a passageway 116 extending between the distal end face and the proximal end face. Passage 116 forms part of the airflow path through the aerosol-generating article 102 and allows air to be drawn from the proximal end of the aerosol-generating article 102, through the fuel heat source 103 and into the aerosol-forming substrate 104 The fiber-reinforced airgel layer 105 is spaced apart from the airflow path through the aerosol-generating article 102 so that air drawn through the airflow path does not come into contact with the fiber-reinforced airgel layer 105 .

[000154] A first substantially air-impermeable non-combustible barrier 106 is arranged between the proximal end of the combustible heat source 103 and the distal end of the aerosol-forming substrate 104, similar to the first barrier 6 described above in relation to Figure 1. However, unlike the first barrier 6 described above, the first barrier 106 includes an opening 120, aligned with the passageway 116, to allow air to pass from the passageway 116 to the aerosol-forming substrate 104.

[000155] A second non-combustible, substantially air-impermeable barrier 117 is coated on the inner surface of the passageway 116. The second barrier 117 isolates the air passing through the passageway 116 from the combustible heat source 103 and the combustion products of the fuel heat source.

[000156] Since the fuel heat source 103 is not a non-blind heat source, the aerosol-generating article 102 does not comprise air inlets arranged in the aerosol-forming substrate 104. aerosol 102, ambient air may be drawn into the aerosol-generating article 102 through the passage 116 through the heat source 103. The air drawn into the aerosol-generating article 102 may flow along an air flow path from the aerosol-generating article 102, through passageway 116, through aerosol-forming substrate 104, transfer element, cooling element, and spacer element to the mouthpiece, and from the mouthpiece to the user for inhalation. The general direction of air flow through the aerosol generating article 102 is indicated by the arrows.

[000157] It will be appreciated that, in some embodiments, other air inlets may be provided in the aerosol generating article as well, in addition to passing air through the combustible heat source.

[000158] The specific embodiments described above are intended to illustrate the invention. However, other embodiments can be made without departing from the scope of the invention as defined in the claims, and it should be understood that the specific embodiments described above are not intended to be limiting.

Claims (15)

1. Aerosol-generating article (2, 102) comprising: an aerosol-forming substrate (4, 104); a fuel heat source (3, 103); one or more airflow paths along which air can be drawn through the aerosol generating article (2, 102) for inhalation by a user; and one or more non-combustible, substantially air-impermeable barriers (6, 106, 107) between the combustible heat source (3, 103) and the aerosol-forming substrate (4, 104), characterized in that the article The aerosol generator (2, 102) further comprises: at least one fiber-reinforced airgel layer (5, 105) circumscribing at least a portion of the length of the fuel heat source (3, 103). 2. Aerosol generating article (2, 102), according to claim 1, characterized in that the at least one fiber-reinforced airgel layer (5, 105) is isolated from the one or more airflow paths such that, during use, air drawn through the aerosol-generating article (2, 102) along the one or more airflow paths does not come into direct contact with at least one layer of fiber-reinforced airgel (5 , 105). 3. Aerosol generating article (2, 102), according to any one of the preceding claims, characterized in that the fuel heat source (3, 103), the aerosol-forming substrate (4, 104) and at least at least one fiber-reinforced airgel layer (5, 105) are arranged such that the temperature of the aerosol-forming substrate (4, 104) does not exceed 375°C during combustion of the combustible heat source (3, 103). 4. Aerosol generating article (2, 102), according to any one of the preceding claims, characterized in that the fiber-reinforced airgel (5, 105) comprises less than 80 percent by weight of airgel (5, 105). 5. Aerosol generating article (2, 102) according to any one of the preceding claims, characterized in that the fiber-reinforced airgel (5, 105) comprises at least 20 percent by weight of fibrous material. 6. Aerosol generating article (2, 102) according to claim 5, characterized in that the fiber-reinforced airgel (5, 105) comprises 20 percent by weight and 70 percent by weight of fibrous material. 7. Aerosol generating article (2, 102), according to any one of the preceding claims, characterized in that the fiber-reinforced airgel (5, 105) comprises at least one of a ceramic fibrous material and a fibrous material of glass. 8. Aerosol generating article (2, 102), according to any one of the preceding claims, characterized in that at least one layer of fiber-reinforced airgel (5, 105) has a thickness of between 0.5 millimeters and 5 millimeters. 9. Aerosol generating article (2, 102), according to any one of the preceding claims, characterized in that the non-combustible barrier (6, 106), substantially impermeable to air, between the combustible heat source (3, 103) and the aerosol-forming substrate (4, 104) of the aerosol-generating article (2, 102) comprises a first barrier (6, 106) that abuts one or both of a proximal end of the fuel heat source (3, 103) and a distal end of the aerosol-forming substrate (4, 104). 10. Aerosol generating article (2), according to any preceding claim, characterized in that the one or more air flow paths comprise one or more air inlets (8) arranged between a proximal end of the heat source fuel (3) and a proximal end of the aerosol generating article (2) so that air can be drawn into the one or more air flow paths of the aerosol generating article (2) through the one or more inlets of air (8), without passing through the fuel heat source (3). 11. Aerosol generating article (102), according to any one of the preceding claims, characterized in that the one or more airflow paths comprise one or more airflow channels (116) along the source of The combustible heat source (103) and the non-combustible, substantially air-impermeable barrier (106) between the combustible heat source (103) and the one or more airflow channels further comprise a second barrier (117) between the combustible heat source (103) and the one or more airflow channels. (103) and the one or more fuel heat source airflow channels (103). 12. Aerosol generating article (2, 102), according to any one of the preceding claims, characterized in that the aerosol generating article (2, 102) further comprises one or more additional layers that surround at least a proximal portion of the combustible heat source (3, 103) and a distal portion of the aerosol-forming substrate (4, 104), the one or more additional layers comprising at least one of: a heat conducting element (9) for transferring heat from the fuel heat source (3, 103) to the aerosol-forming substrate (4, 104), and a layer of cigarette paper (7, 107). 13. Aerosol generating article (2, 102), according to claim 12, characterized in that at least one fiber-reinforced airgel layer (5, 105) is a radially outer layer that overlaps at least one portion of to one or more additional layers. A method of forming the aerosol-generating article (2, 102) as defined in any one of claims 1 to 13, the method comprising: arranging a combustible heat source (3, 103) to heat an aerosol-forming substrate ( 4, 104); providing one or more airflow paths along which air can be drawn through the aerosol generating article (2, 102) for inhalation by a user, and isolating the combustible heat source (3, 103) from the one or more more airflow paths, so that, during use, air drawn through the aerosol generating article (2, 102) along the one or more airflow paths does not come into direct contact with the heat source fuel (3, 103); characterized in that the method further comprises: circumscribing at least a portion of the length of the fuel heat source (3, 103) with at least one fiber-reinforced airgel layer (5, 105). 15. Method of forming an aerosol generating article (2, 102), according to claim 14, characterized in that the circumscription of at least a portion of the length of the fuel heat source (3, 103) with at least at least one layer of fiber-reinforced airgel (5, 105) comprises: providing a strip of fiber-reinforced airgel (5, 105) with opposite ends; wrapping a strip around the fuel heat source (3, 103) such that the fuel heat source (3, 103) is circumscribed by at least one layer of fiber-reinforced airgel (5, 105); overlap opposite ends of the strip; and bringing the overlapping ends together to secure the at least one fiber-reinforced airgel layer (5, 105) to the fuel heat source (3, 103).

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