Aerosol Generation

The present application is a Continuation of U.S. application Ser. No. 17/250,498 filed Jan. 28, 2021, which is a National Phase entry of PCT Application No. PCT/EP2019/070675, filed Jul. 31, 2019, which claims priority from Great Britain Patent Application No. 1812505.4 filed Jul. 31, 2018, each of which is fully incorporated herein by reference.

The present invention relates to aerosol generation.

Smoking articles such as cigarettes, cigars and the like burn tobacco during use to create tobacco smoke. Alternatives to these types of articles release an inhalable aerosol or vapor by releasing compounds from a substrate material by heating without burning. These may be referred to as non-combustible smoking articles or aerosol generating assemblies.

One example of such a product is a heating device which release compounds by heating, but not burning, a solid aerosolizable material. This solid aerosolizable material may, in some cases, contain a tobacco material. The heating volatilizes at least one component of the material, typically forming an inhalable aerosol. These products may be referred to as heat-not-burn devices, tobacco heating devices or tobacco heating products. Various different arrangements for volatilizing at least one component of the solid aerosolizable material are known.

As another example, there are e-cigarette/tobacco heating product hybrid devices, also known as electronic tobacco hybrid devices. These hybrid devices contain a liquid source (which may or may not contain nicotine) which is vaporized by heating to produce an inhalable vapor or aerosol. The device additionally contains a solid aerosolizable material (which may or may not contain a tobacco material) and components of this material are entrained in the inhalable vapor or aerosol to produce the inhaled medium.

A first aspect of the invention provides an aerosol generating material comprising an aerosol-forming layer, the aerosol-forming layer comprising an amorphous solid, wherein the aerosol-forming layer has a thickness of 0.015 mm to 1.0 mm. In one embodiment, the aerosol-forming layer has a thickness of from 0.05 mm to 1.0 mm.

In one embodiment, the amorphous solid comprises one or more of an active substance, an aerosol generating agent, a flavorant and a gelling agent. In a particular embodiment, the amorphous solid comprises one or more of nicotine, a tobacco material, an aerosol generating agent, a flavorant and a gelling agent.

A second aspect of the invention provides an aerosol generating assembly comprising an aerosol generating material according to the first aspect of the invention and a heater configured to heat but not burn the aerosol generating material.

A third aspect of the invention provides an aerosol generating article for use in an aerosol generating assembly, the article comprising an aerosol generating material according to the first aspect.

A fourth aspect of the invention provides a method of making an aerosol generating material according to the first aspect.

Further aspects of the invention described herein may provide the use of the aerosol generating material, the aerosol generating article or the aerosol generating assembly, in the generation of an inhalable aerosol.

Further features and advantages of the invention will become apparent from the following description, given by way of example only, and with reference to the accompanying figures.

The aerosol-forming layer described herein comprises an “amorphous solid”, which may alternatively be referred to as a “monolithic solid” (i.e. non-fibrous), or as a “dried gel”. The amorphous solid is a solid material that may retain some fluid, such as liquid, within it. In some cases, the aerosol-forming layer comprises from about 50 wt %, 60 wt % or 70 wt % of amorphous solid, to about 90 wt %, 95 wt % or 100 wt % of amorphous solid. In some cases, the aerosol-forming layer consists of amorphous solid.

As described above, the invention provides an aerosol generating material comprising an aerosol-forming layer, the aerosol-forming layer comprising an amorphous solid, and wherein the aerosol-forming layer has a thickness of about 0.015 mm to about 1.0 mm. Suitably, the thickness may be in the range of about 0.05 mm, 0.1 mm or 0.15 mm to about 0.5 mm or 0.3 mm. The inventors have found that a material having a thickness of 0.2 mm is particularly suitable. The aerosol-forming layer may comprise more than one layer, and the thickness described herein refers to the aggregate thickness of those layers.

The inventors have established that if the aerosol-forming layer is too thick, then heating efficiency is compromised. This adversely affects the power consumption and the timing of aerosol delivery in use. Conversely, if the aerosol-forming layer is too thin, it is difficult to manufacture and handle; a very thin material is harder to cast and may be fragile, compromising aerosol formation in use.

The inventors have established that the layer thicknesses stipulated herein optimize the material properties in view of these competing considerations.

The thickness stipulated herein is a mean thickness for the material. In some cases, the amorphous solid thickness may vary by no more than 25%, 20%, 15%, 10%, 5% or 1%.

In some cases, the aerosol generating material may comprise embedded heating means, such as resistive or inductive heating elements. For example, the heating means may be embedded in the amorphous solid.

The aerosol generating material may comprise a carrier on which the amorphous solid is provided.provides a schematic illustration of such an aerosol generating material. The laminate structure (indicated by dotted lines) includes a carrier layerand an amorphous solid layer.

The carrier functions as a support on which the amorphous solid layer forms, easing manufacture. The carrier may provide tensile strength to the amorphous solid layer, easing handling.

The carrier may be any suitable material which can be used to support an amorphous solid. In some cases, the carrier may be formed from materials selected from metal foil, paper, carbon paper, greaseproof paper, ceramic, carbon allotropes such as graphite and graphene, plastic, cardboard, wood or combinations thereof. In some cases, the carrier may comprise or consist of a tobacco material, such as a sheet of reconstituted tobacco. In some cases, the carrier may be formed from materials selected from metal foil, paper, cardboard, wood or combinations thereof. In some cases, the carrier itself be a laminate structure comprising layers of materials selected from the preceding lists. In some cases, the carrier may also function as a flavor carrier. For example, the carrier may be impregnated with a flavorant or with tobacco extract.

In some cases, the carrier may be magnetic. This functionality may be used to fasten the carrier to the assembly in use, or may be used to generate particular amorphous solid shapes. In some cases, the aerosol generating material may comprise one or more magnets which can be used to fasten the material to an induction heater in use.

In some cases, the carrier may be substantially or wholly impermeable to gas and/or aerosol. This prevents aerosol or gas passage through the carrier layer, thereby controlling the flow and ensuring it is delivered to the user. This can also be used to prevent condensation or other deposition of the gas/aerosol in use on, for example, the surface of a heater provided in an aerosol generating assembly. Thus, consumption efficiency and hygiene can be improved in some cases.

In one case, the surface of the carrier that abuts the amorphous solid may be porous. For example, in some cases, the carrier comprises paper. The inventors have found that a porous carrier such as paper is particularly suitable for the present invention; the porous layer abuts the amorphous solid layer and forms a strong bond. The amorphous solid is formed by drying a gel and, without being limited by theory, it is thought that the slurry from which the gel is formed partially impregnates the porous carrier (e.g. paper) so that when the gel sets and forms cross-links, the carrier is partially bound into the gel. This provides a strong binding between the gel and the carrier (and between the dried gel and the carrier). The porous layer (e.g. paper) may also be used to carry flavors. In some cases, the porous layer may comprise paper, suitably having a porosity of 0-300 Coresta Units (CU), suitably 5-100 CU or 25-75 CU.

Additionally, surface roughness may contribute to the strength of bond between the amorphous material and the carrier. The inventors have found that the paper roughness (for the surface abutting the carrier) may suitably be in the range of 50-1000 Bekk seconds, suitably 50-150 Bekk seconds, suitably 100 Bekk seconds (measured over an air pressure interval of 50.66-48.00 kPa). (A Bekk smoothness tester is an instrument used to determine the smoothness of a paper surface, in which air at a specified pressure is leaked between a smooth glass surface and a paper sample, and the time (in seconds) for a fixed volume of air to seep between these surfaces is the “Bekk smoothness”.)

Conversely, the surface of the carrier facing away from the amorphous solid may be arranged in contact with the heater, and a smoother surface may provide more efficient heat transfer. Thus, in some cases, the carrier is disposed so as to have a rougher side abutting the amorphous material and a smoother side facing away from the amorphous material.

In one particular case, the carrier may be a paper-backed foil; the paper layer abuts the amorphous solid layer and the properties discussed in the previous paragraphs are afforded by this abutment. The foil backing is substantially impermeable, providing control of the aerosol flow path. A metal foil backing may also serve to conduct heat to the amorphous solid.

In another case, the foil layer of the paper-backed foil abuts the amorphous solid. The foil is substantially impermeable, thereby preventing water provided in the amorphous solid to be absorbed into the paper which could weaken its structural integrity.

In some cases, the carrier is formed from or comprises metal foil, such as aluminum foil. A metallic carrier may allow for better conduction of thermal energy to the amorphous solid. Additionally, or alternatively, a metal foil may function as a susceptor in an induction heating system. In particular embodiments, the carrier comprises a metal foil layer and a support layer, such as cardboard. In these embodiments, the metal foil layer may have a thickness of less than 20 μm, such as from about 1 μm to about 10 μm, suitably about 5 μm.

In some cases, the carrier may have a thickness of between about 0.010 mm, and about 2.5 mm, suitably from about 0.015 mm, 0.017 mm 0.02 mm, 0.05 mm or 0.1 mm to about 1.5 mm, 1.0 mm, or 0.5 mm.

In some cases, the amorphous solid may comprise 1-60 wt % of a gelling agent wherein these weights are calculated on a dry weight basis.

Suitably, the amorphous solid may comprise from about 1 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt % or 25 wt % to about 60 wt %, 50 wt %, 45 wt %, 40 wt %, 35 wt %, 30 wt % or 27 wt % of a gelling agent (all calculated on a dry weight basis). For example, the amorphous solid may comprise 1-50 wt %, 5-40 wt %, 10-30 wt % or 15-27 wt % of a gelling agent.

In some embodiments, the gelling agent comprises a hydrocolloid. In some embodiments, the gelling agent comprises one or more compounds selected from the group comprising alginates, pectins, starches (and derivatives), celluloses (and derivatives), gums, silica or silicones compounds, clays, polyvinyl alcohol and combinations thereof. For example, in some embodiments, the gelling agent comprises one or more of alginates, pectins, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethylcellulose, pullulan, xanthan gum guar gum, carrageenan, agarose, acacia gum, fumed silica, PDMS, sodium silicate, kaolin and polyvinyl alcohol. In some cases, the gelling agent comprises alginate and/or pectin, and may be combined with a setting agent (such as a calcium source) during formation of the amorphous solid. In some cases, the amorphous solid may comprise a calcium-crosslinked alginate and/or a calcium-crosslinked pectin.

In some embodiments, the gelling agent comprises alginate, and the alginate is present in the amorphous solid in an amount of from 10-30 wt % of the amorphous solid (calculated on a dry weight basis). In some embodiments, alginate is the only gelling agent present in the amorphous solid. In other embodiments, the gelling agent comprises alginate and at least one further gelling agent, such as pectin.

In some embodiments the amorphous solid may include gelling agent comprising carrageenan.

Suitably, the amorphous solid may comprise from about 5 wt %, 10 wt %, 15 wt %, or 20 wt % to about 80 wt %, 70 wt %, 60 wt %, 55 wt %, 50 wt %, 45 wt % 40 wt %, or 35 wt % of an aerosol generating agent (all calculated on a dry weight basis). The aerosol generating agent may act as a plasticizer. For example, the amorphous solid may comprise 10-60 wt %, 15-50 wt % or 20-40 wt % of an aerosol generating agent. In some cases, the aerosol generating agent comprises one or more compound selected from erythritol, propylene glycol, glycerol, triacetin, sorbitol and xylitol. In some cases, the aerosol generating agent comprises, consists essentially of or consists of glycerol. The inventors have established that if the content of the plasticizer is too high, the amorphous solid may absorb water resulting in a material that does not create an appropriate consumption experience in use. The inventors have established that if the plasticizer content is too low, the amorphous solid may be brittle and easily broken. The plasticizer content specified herein provides an amorphous solid flexibility which allows the amorphous solid sheet to be wound onto a bobbin, which is useful in manufacture of aerosol generating articles.

In some cases, the amorphous solid may comprise a flavor. Suitably, the amorphous solid may comprise up to about 60 wt %, 50 wt %, 40 wt %, 30 wt %, 20 wt %, 10 wt % or 5 wt % of a flavor. In some cases, the amorphous solid may comprise at least about 0.1 wt %, 0.5 wt %, 1 wt %, 2 wt %, 5 wt % 10 wt %, 20 wt % or 30 wt % of a flavor (all calculated on a dry weight basis). For example, the amorphous solid may comprise 0.1-60 wt %, 1-60 wt %, 5-60 wt %, 10-60 wt %, 20-50 wt % or 30-40 wt % of a flavor. In some cases, the flavor (if present) comprises, consists essentially of or consists of menthol. In some cases, the amorphous solid does not comprise a flavor.

In some cases, the amorphous solid additionally comprises an active substance. For example, in some cases, the amorphous solid additionally comprises a tobacco material and/or nicotine. For example, the amorphous solid may additionally comprise powdered tobacco and/or nicotine and/or a tobacco extract. In some cases, the amorphous solid may comprise from about 1 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt % or 25 wt % to about 70 wt %, 50 wt %, 45 wt % or 40 wt % (calculated on a dry weight basis) of active substance. In some cases, the amorphous solid may comprise from about 1 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt % or 25 wt % to about 70 wt %, 60 wt %, 50 wt %, 45 wt % or 40 wt % (calculated on a dry weight basis) of a tobacco material and/or nicotine.

In some cases, the amorphous solid comprises an active substance such as tobacco extract. In some cases, the amorphous solid may comprise 5-60wt % (calculated on a dry weight basis) of tobacco extract. In some cases, the amorphous solid may comprise from about 1wt %, 5wt %, 10wt %, 15wt %, 20wt % or 25wt % to about 55wt %, 50wt %, 45wt % or 40wt % (calculated on a dry weight basis) tobacco extract. For example, the amorphous solid may comprise 5-60wt %, 10-55wt % or 25-55wt % of tobacco extract. The tobacco extract may contain nicotine at a concentration such that the amorphous solid comprises 1wt % 1.5wt %, 2wt % or 2.5wt % to about 6wt %, 5wt %, 4.5wt % or 4wt % (calculated on a dry weight basis) of nicotine. In some cases, there may be no nicotine in the amorphous solid other than that which results from the tobacco extract.

In some embodiments the amorphous solid comprises no tobacco material but does comprise nicotine. In some such cases, the amorphous solid may comprise from about 1wt %, 2wt %, 3wt % or 4wt % to about 20wt %, 15wt %, 10wt % or 5wt % (calculated on a dry weight basis) of nicotine. For example, the amorphous solid may comprise 1-20wt % or 2-5wt % of nicotine.

In some cases, the total content of active substance and/or flavor may be at least about 0.1wt %, 1wt %, 5wt %, 10wt %, 20wt %, 25wt % or 30wt %. In some cases, the total content of active substance and/or flavor may be less than about 70wt %, 60wt %, 50wt % or 40wt % (all calculated on a dry weight basis).

In some cases, the total content of tobacco material, nicotine and flavor may be at least about 0.1wt %, 1wt %, 5wt %, 10wt %, 20wt %, 25wt % or 30wt %. In some cases, the total content of tobacco material, nicotine and flavor may be less than about 70wt %, 60wt %, 50wt % or 40wt % (all calculated on a dry weight basis).

In some embodiments, the amorphous solid is a hydrogel and comprises less than about 20wt % of water calculated on a wet weight basis. In some cases, the hydrogel may comprise less than about 15wt %, 12wt % or 10wt % of water calculated on a wet weight basis (WWB). In some cases, the hydrogel may comprise at least about 1wt %, 2wt % or at least about 5wt % of water (WWB).

The amorphous solid may be made from a gel, and this gel may additionally comprise a solvent, included at 0.1-50wt %. However, the inventors have established that the inclusion of a solvent in which the flavor is soluble may reduce the gel stability and the flavor may crystalize out of the gel. As such, in some cases, the gel does not include a solvent in which the flavor is soluble.

In some embodiments, the amorphous solid comprises less than 60wt % of a filler, such as from 1wt % to 60wt %, or 5wt % to 50wt %, or 5wt % to 30wt %, or 10wt % to 20wt %.

In other embodiments, the amorphous solid comprises less than 20wt %, suitably less than 10wt % or less than 5wt % of a filler. In some cases, the amorphous solid comprises less than 1wt % of a filler, and in some cases, comprises no filler.

The filler, if present, may comprise one or more inorganic filler materials, such as calcium carbonate, perlite, vermiculite, diatomaceous earth, colloidal silica, magnesium oxide, magnesium sulphate, magnesium carbonate, and suitable inorganic sorbents, such as molecular sieves. The filler may comprise one or more organic filler materials such as wood pulp, cellulose and cellulose derivatives. In particular, in some cases, the amorphous solid comprises no calcium carbonate such as chalk.

In particular embodiments which include filler, the filler is fibrous. For example, the filler may be a fibrous organic filler material such as wood pulp, hemp fiber, cellulose or cellulose derivatives. Without wishing to be bound by theory, it is believed that including fibrous filler in an amorphous solid may increase the tensile strength of the material. This may be particularly advantageous in examples wherein the amorphous solid is provided as a sheet, such as when an amorphous solid sheet circumscribes a rod of aerosolizable material.

In some embodiments, the amorphous solid does not comprise tobacco fibers. In particular embodiments, the amorphous solid does not comprise fibrous material.

In some embodiments, the aerosol generating material does not comprise tobacco fibers. In particular embodiments, the aerosol generating material does not comprise fibrous material.