EP4699456A1

EP4699456A1 - Aerosol-generating sheet, flavor-generating composition, and heat-not-burn type smoking article

Info

Publication number: EP4699456A1
Application number: EP23934106.8A
Authority: EP
Inventors: Takeshi Shinkawa
Original assignee: Japan Tobacco Inc
Current assignee: Japan Tobacco Inc
Priority date: 2023-04-21
Filing date: 2023-04-21
Publication date: 2026-02-25
Also published as: CN120936258A; KR20250172949A; JPWO2024218963A1; WO2024218963A1

Abstract

This aerosol-generating sheet comprises (A) 15-50% by weight of a tobacco extract, (B) 6-20% by weight of a binder, and (C) 15-60% by weight of an aerosol source, and has a basis weight of 0.10-0.25 mg/mm².

Description

TECHNICAL FIELD

The present invention relates to an aerosol-generating sheet, a flavor-generating composition, and a heat-not-burn smoking article.

BACKGROUND ART

Heated smoking articles which are heated to generate a flavor component have been proposed. For example, PTL 1 discloses a cast sheet for a heated smoking article, the cast sheet including a tobacco content of at least 40% on a dry weight basis, comprising non-tobacco fiber at 1-5 wt% on a dry weight basis, an aerosol-former content in excess of 5% on a dry weight basis, and an exogenous binder, and having a basis weight of 100 g/m²-300 g/m²

CITATION LIST

PATENT LITERATURE

PTL 1: JP 6883614 B2

SUMMARY OF INVENTION

TECHNICAL PROBLEM

A flavor source in a smoking article needs to deliver a flavor component efficiently. In view of this situation, the problem addressed by the present invention lies in providing an aerosol-generating sheet with high volatilization of components.

SOLUTION TO PROBLEM

The inventors found that the problem above can be solved by means of an aerosol-generating sheet having a specific composition and basis weight. That is to say, the problem above is solved by a the following invention.

Aspect 1

An aerosol-generating sheet comprising: (A) 15-50 wt% of a tobacco extract,

(B) 6-20 wt% of a binder; and
(C) 15-60 wt% of an aerosol source, wherein the basis weight of the aerosol-generating sheet is 0.10-0.25 mg/mm².

Aspect 2

The sheet as disclosed in aspect 1, wherein the density is 0.2-0.6 mg/mm³.

Aspect 3

The sheet as disclosed in aspect 1 or 2, internally comprising a plurality of dispersed air bubbles, or having through-holes penetrating both main faces.

Aspect 4

The sheet as disclosed in any of aspects 1 to 3, wherein the binder is selected from the group consisting of: cellulose derivatives, xanthan gum, guar gum, carrageenan, locust bean gum, alginic acid, sodium alginate, starch, soluble soybean polysaccharide, and combinations thereof.

Aspect 5

The sheet as disclosed in any of aspects 1 to 4, wherein the cellulose derivatives include hydroxyalkyl alkyl cellulose, carboxyalkyl cellulose, or alkyl cellulose.

Aspect 6

The sheet as disclosed in aspect 5, wherein the cellulose derivatives include hydroxypropyl methylcellulose (HPMC) and carboxymethyl cellulose (CMC), a weight ratio of HPMC and CC being 0.5:1-2:1.

Aspect 7

The aerosol-generating sheet as disclosed in any of aspects 1 to 6, further comprising: (D) fiber, wherein a weight ratio of the binder (B) and fiber (D) component satisfies: 0.30≤(B)/(D)≤1.2.

Aspect 8

The aerosol-generating sheet as disclosed in any of aspects 1 to 7, wherein a weight ratio of the aerosol source (C) and the binder (B) satisfies: 2.0≤(C)/(B)≤4.0.

Aspect 9

The aerosol-generating sheet as disclosed in any of aspects 1 to 8, wherein a moisture release rate is 0.15 (wt%/sec) or greater, the moisture release rate being obtained by the following method: 1) the sheet is heated at 100°C to remove water, and a weight reduction - time curve is acquired from the relationship between a weight reduction rate and time; and 2) the moisture release rate is obtained from an initial inclination of the curve.

Aspect 10

A flavor-generating composition comprising the aerosol-generating sheet as disclosed in any of aspects 1 to 9, and leaf tobacco.

Aspect 11

A heat-not-burn smoking article comprising a tobacco segment which includes the aerosol-generating sheet as disclosed in any of aspects 1 to 9, or the flavor-generating composition as disclosed in aspect 10.

Aspect 12

A heat-not-burn smoking system comprising the heat-not-burn smoking article as disclosed in aspect 11, and a heating device.

Aspect 13

A method for producing the aerosol-generating sheet as disclosed in any of aspects 1 to 9, comprising: a step of stir-foaming abovementioned (A), (B) and (C) to prepare a mixture incorporating air bubbles; and
a step of forming the mixture into a sheet.

Aspect 14

The production method as disclosed in aspect 13, wherein a solid/liquid ratio of the mixture is 1:1-1:8, and a weight ratio (C)/(B) of the mixture satisfies: 2.0≤(C)/(B)≤4.0.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention makes it possible to provide an aerosol-generating sheet with high volatilization of components.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 shows weight reduction behavior of an aerosol-generating sheet at 200°C.
Fig. 2 shows weight reduction behavior of an aerosol-generating sheet at 100°C.
Fig. 3 shows an embodiment of a heat-not-burn smoking article.
Fig. 4 shows an embodiment of a heat-not-burn smoking system.

DESCRIPTION OF EMBODIMENTS

As used in the present disclosure, the range "X-Y" includes X and Y as the end values. Unless otherwise specified, weight and wt% are dry weight and dry wt%. Dry weight is the weight excluding the weight of water.

1. Aerosol-generating sheet

An aerosol-generating sheet (also referred to below as a "sheet") is a sheet which generates an aerosol as a result of being heated. In one embodiment, the aerosol-generating sheet comprises: (A) 15-50 wt% of a tobacco extract; (B) 6-20 wt% of a binder; and (C) 15-60 wt% of an aerosol source, and has a basis weight of 0.10-0.25 mg/mm².

(1) Tobacco extract (A)

The tobacco extract (also referred to below as "component (A)") is an active ingredient (an ingredient other than a medium used for extraction) contained in an extract liquid obtained by extracting a tobacco raw material. The extraction may be carried out in a known manner, and the following methods may be cited by way of example. 1) A method in which a tobacco raw material is extracted using a medium to obtain a tobacco extract; 2) a method in which a medium is added to a tobacco raw material, the mixture is heated, and the vapor that is generated is collected to obtain a tobacco extract; and 3) a method in which a heat-vaporized medium is allowed to pass through a tobacco raw material, and the vapor that has passed through is collected to obtain a tobacco extract. Media which may be cited include water, hydrophilic organic solvents such as alcohol, and combinations thereof, but the medium is preferably water or comprises water.
In the method of 1), water is preferably used as the medium in the interests of workability, etc. Furthermore, in the methods of 2) and 3), glycerol, propylene glycol, triacetin, 1,3-butanediol, or an alcohol such as ethanol is preferably used as the medium in the interests of work efficiency. Acids or alkalis can also be used, as needed, for extraction. The liquid containing the tobacco extract and the medium that is obtained by the extraction is called the tobacco extract liquid.
Raw materials of the Nicotiana genus, such as Nicotiana tabacum and Nicotiana rustica, can be used as the tobacco raw material, for example. Examples of Nicotiana tabacum that can be used include varieties such as Burley tobacco and Yellow tobacco. Oriental tobacco or Burley tobacco which is an indigenous species of the Nicotiana genus may also be used.
The tobacco raw material may be a cut or powdered tobacco raw material (also referred to below as "raw material pieces"). In such cases, the particle size of the raw material pieces is preferably 0.5-1.18 mm. Such raw material pieces are obtained via sifting in accordance with JIS Z 8815 using a stainless steel sieve conforming to JIS Z 8801, for example. For example, 1) raw material pieces are sifted over a 20-minute period by means of dry mechanical shaking using a stainless steel sieve having 1.18 mm openings to obtain raw material pieces that pass through the stainless sieve having 1.18 mm openings. 2) Raw material pieces are then sifted over a 20-minute period by means of dry mechanical shaking using a stainless steel sieve having 0.50 mm openings to remove raw material pieces that pass through the stainless sieve having 0.50 mm openings. It is thus possible to prepare raw material pieces that pass through a stainless steel sieve of a specified upper limit (1.18 mm openings) and that do not pass through a stainless steel sieve of a specified lower limit (0.50 mm openings).
In one aspect, the tobacco raw material is treated with an alkali. Flavor components generated by way of this treatment are collected to prepare a tobacco extract liquid and a tobacco extract residue. In this process, the flavor components may be extracted in the form of a gas from the alkali-treated tobacco raw material, and the gas may be introduced into water in order to obtain a tobacco extract liquid in which the flavor components have migrated to a liquid.
The alkaline substance is preferably an alkaline liquid such as potassium carbonate aqueous solution, for example. In this process, the alkaline substance is supplied until the pH of the tobacco raw material is within a specific range. The pH is preferably at least 8.0, and more preferably 8.9 to 9.7. The pH of the tobacco raw material refers to the pH of the water when the tobacco raw material is mixed with 10 times the amount of water.
The moisture content of the tobacco raw material which is extracted is not limited, but is preferably around 5-30 wt% in the interests of efficient flavor component extraction. The moisture content of the tobacco raw material can be determined by a known method; for example, the moisture content can be defined as the amount of weight reduction at the point in time when a 1 g sample has been collected and heated at 105°C and is heated until the rate of change in weight is no greater than 1 mg/min. This can be determined, for example, using a moisture analyzer having a halogen heat source (such as MB45, manufactured by OHAUS CORPORATION).
The tobacco extract preferably comprises a large amount of nicotine. From this perspective, the amount of nicotine in the extraction residue is preferably no greater than 1 wt% of the amount of nicotine in the tobacco raw material, and preferably no greater than 0.5 wt%.
The aerosol-generating sheet has a tobacco extract content of 15-50 wt%. An amount below this lower limit value will result in an inadequate smoking taste. An amount above this upper limit value will result in a sense of inhibited flavor. From this perspective, the content of component (A) is preferably 25-45 wt%.

(2) Binder (B)

The binder (also referred to below as "component (B)") imparts strength to the sheet. A well-known binder may be used, but it is preferably selected from the group consisting of: cellulose derivatives, xanthan gum, guar gum, carrageenan, locust bean gum, alginic acid, sodium alginate, starch, soluble soybean polysaccharide, and combinations thereof. Cellulose derivatives which may be cited include alkyl cellulose, hydroxyalkyl alkyl cellulose, and carboxyalkyl cellulose. Cellulose derivatives which may be cited more specifically include: methylcellulose, hydroxyethyl methylcellulose (HEMC), hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), carboxymethyl cellulose (CMC), and salts thereof. Among these, hydroxypropyl methylcellulose (HPMC) and carboxymethyl cellulose (CMC) are preferably used. In this case, a blending ratio (weight ratio) of HPMC and CMC is preferably 0.5:1-2:1. By setting this blending ratio, it is possible to improve foamability of the sheet, while also making air bubbles less likely to collapse during drying.
The amount of component (B) in the aerosol-generating sheet is 6-20 wt%. An amount below this lower limit value will result in inadequate strength. Furthermore, if component (B) is below the lower limit value, there will be a drop in foamability, making it more difficult for air bubbles, through-holes or indentations to be formed in the aerosol-generating sheet. This therefore makes it more difficult for the desired basis weight or density to be achieved, thus leading to a drop in volatilization of components of the aerosol-generating sheet. An amount above the upper limit value will result in an increase in the density of the sheet, causing a drop in volatilization of components of the aerosol-generating sheet. However, the amount of component (B) is appropriately adjusted with regard to amounts of other components, as will be described later.

(3) Aerosol source (C)

The aerosol source (also referred to below as "component (C)") is a substance which forms an aerosol as a result of being heated. Aerosol sources which may be cited include polyhydric alcohols such as glycerol or polyethylene glycol. The amount of component (C) in the sheet is 15-60 wt%. An amount below the lower limit value will result in an inadequate amount of smoke during smoking. There will also be a drop in the elasticity of the sheet, making it more difficult for air bubbles, through-holes and indentations to be formed when a sheet is produced. This therefore makes it more difficult for the desired basis weight or density to be achieved, thus leading to a drop in volatilization of components of the aerosol-generating sheet. An amount above the upper limit value will result in a drop in the ease of handling of the sheet. There will also be an increase in the basis weight and density of the sheet, causing a drop in volatilization of components of the aerosol-generating sheet. From this perspective, the amount is preferably 15-50 wt%, and more preferably 20-40 wt%.
Components (B) and (C) considerably affect the density and strength of the sheet. Setting the amounts of components (B) and (C) in suitable ranges has advantages such as making it possible to ensure a sufficient amount of smoke during smoking, making it possible to improve volatilization of components, and improving ease of handling of the sheet. Adequate sheet strength can also be achieved. From this perspective, a weight ratio (C), (B) of components (C) and (B) is preferably 2.0-4.0, more preferably 2.0-3.0, and even more preferably 2.5-3.0. When the weight ratio (C)/(B) is in this range, the content of component (B) in the sheet is more preferably 10 wt% or greater.

(4) Fiber (D)

The aerosol-generating sheet preferably comprises fiber (also referred to below as "component (D)"). Wood fiber and non-wood fiber are known as examples of fiber, but a sheet comprising non-wood fiber has the advantage of a better liquid support capacity than a sheet comprising wood fiber. The amount of non-wood fiber added can thus be reduced to increase the amount of components that contribute to smoking flavor. From this perspective, the fiber is preferably a non-wood fiber. Non-wood fiber is a fiber that is not derived from wood, and may be tobacco fiber or a fiber other than tobacco. From the perspective of imparting strength, dietary fiber is preferred as the non-wood fiber. Dietary fiber is a dietary component that is indigestible by human digestive enzymes, and is more preferably water-insoluble dietary fiber. The dietary fiber may be porous, i.e., may be sponge-like. The fiber is preferably citrus fiber because it is readily available, etc. Citrus fiber is primarily composed of the mesocarp of citrus fruits. Dietary fiber may also be short fiber or columnar particles that have a small aspect ratio. Citrus fiber is particularly preferred because it can be used in small amounts to impart strength to materials for smoking articles. In one aspect, the content of component (D) in materials for smoking articles is 10-30 wt%. An amount below this lower limit value will result in a drop in the ease of handling of the sheet, and also a drop in the strength of the sheet. Meanwhile, an amount above this upper limit value may dilute the flavor and may detract from the taste.
Components (B) and (D) considerably affect the density and strength of the sheet. Setting the amounts of components (B) and (D) in suitable ranges makes it possible to improve the ease of handling of the sheet and also to achieve adequate strength of the sheet. Furthermore, air bubbles, through-holes, or indentations are also readily formed in the aerosol-generating sheet, and it is possible to achieve the desired basis weight or density. Volatilization of components of the aerosol-generating sheet is increased as a result. From this perspective, a weight ratio (B)/(D) of components (B) and (D) is preferably 0.30-1.2, and more preferably 0.6-1.2.

(5) Other components

The sheet may also contain well-known flavoring materials. Menthol or the like may be cited as an example of a flavoring material, but this is not limiting, and the flavoring materials mentioned below can be used. The amounts of the flavoring materials may also be known amounts. One type of flavoring material may be used alone, or two or more may be used in combination.
Preferred flavoring materials are given below. Acetanisole, acetophenone, acetylpyrazine, 2-acetylthiazole, alfalfa extract, amyl alcohol, amyl butyrate, trans-anethole, star anise oil, apple juice, Peru Balsam oil, beeswax absolute, benzaldehyde, benzoin resinoid, benzyl alcohol, benzyl benzoate, benzyl phenylacetate, benzyl propionate, 2,3-butanedione, 2-butanol, butyl butyrate, butyric acid, caramel, cardamom oil, carob absolute, β-carotene, carrot juice, L-carvone, β-caryophyllene, cassia bark oil, cedar wood oil, celery seed oil, chamomile oil, cinnamaldehyde, cinnamic acid, cinnamyl alcohol, cinnamyl cinnamate, citronella oil, DL-citronellol, clary sage extract, cocoa, coffee, cognac oil, coriander oil, cuminaldehyde, davana oil, δ-decalactone, γ-decalactone, decanoic acid, dill herb oil, 3,4-dimethyl-1,2-cyclopentanedione, 4,5-dimethyl-3-hydroxy-2,5-dihydrofuran-2-one, 3,7-dimethyl-6-octenoic acid, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2-ethyl methylbutyrate, ethyl acetate, ethyl butyrate, ethyl hexanoate, ethyl isovalerate, ethyl lactate, ethyl laurate, ethyl levulinate, ethyl maltol, ethyl octanoate, ethyl oleate, ethyl palmitate, ethyl phenylacetate, ethyl propionate, ethyl stearate, ethyl valerate, ethyl vanillin, ethyl vanillin glucoside, 2-ethyl-3,(5 or 6)-dimethylpyrazine, 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone, 2-ethyl-3-methylpyrazine, eucalyptol, fenugreek absolute, genet absolute, gentian root infusion, geraniol, geranyl acetate, grape juice, guaiacol, guava extract, γ-heptalactone, γ-hexalactone, hexanoic acid, cis-3-hexen-1-ol, hexyl acetate, hexyl alcohol, hexyl phenylacetate, honey, 4-hydroxy-3-pentenoic acid lactone, 4-hydroxy-4-(3-hydroxy-1-butenyl)-3,5,5-trimethyl-2-cyclohexen-1-one, 4-(para-hydroxyphenyl)-2-butanone, 4-hydroxyundecanoic acid sodium, immortelle absolute, β-ionone, isoamyl acetate, isoamyl butyrate, isoamyl phenylacetate, isobutyl acetate, isobutyl phenylacetate, jasmine absolute, kola nut tincture, labdanum oil, lemon terpeneless oil, glycyrrhiza extract, linalool, linalyl acetate, lovage root oil, maltol, maple syrup, menthol, menthone, acetic acid L-menthyl, paramethoxybenzaldehyde, methyl-2-pyrrolyl ketone, methyl anthranilate, methyl phenylacetate, methyl salicylate, 4'-methylacetophenone, methylcyclopentenolone, 3-methylvaleric acid, mimosa absolute, molasses, myristic acid, nerol, nerolidol, γ-nonalactone, nutmeg oil, δ-octalactone, octanal, octanoic acid, orange flower oil, orange oil, orris root oil, palmitic acid, ω-pentadecalactone, peppermint oil, petitgrain Paraguay oil, phenethyl alcohol, phenethyl phenylacetate, phenylacetic acid, piperonal, plum extract, propenyl guaethol, propyl acetate, 3-propylidene phthalide, prune juice, pyruvic acid, raisin extract, rose oil, rum, sage oil, sandalwood oil, spearmint oil, styrax absolute, marigold oil, tea distillate, α-terpineol, terpinyl acetate, 5,6,7,8-tetrahydroquinoxaline, 1,5,5,9-tetramethyl-13-oxacyclo(8.3.0.0(4.9))tridecane, 2,3,5,6-tetramethylpyrazine, thyme oil, tomato extract, 2-tridecanone, triethyl citrate, 4-(2,6,6-trimethyl-1-cyclohexenyl)-2-buten-4-one, 2,6,6-trimethyl-2-cyclohexen-1,4-dione, 4-(2,6,6-trimethyl-1,3-cyclohexadienyl)-2-buten-4-one, 2,3,5-trimethylpyrazine, γ-undecalactone, γ-valerolactone, vanilla extract, vanillin, veratraldehyde, violet leaf absolute, N-ethyl-p-menthane-3-carboamide (WS-3), and ethyl-2-(p-menthane-3-carboxamide) acetate (WS-5).

(6) Characteristics

1) Basis weight

The basis weight of the aerosol-generating sheet is 0.10-0.25 mg/mm². An amount below this lower limit value will result in inadequate strength of the sheet. If the basis weight exceeds the upper limit value, there will be a drop in volatilization of components of the aerosol-generating sheet. From this perspective, the basis weight is preferably 0.10-0.20 mg/mm². The basis weight is obtained from the weight and thickness of the sheet.

2) Density

The density of the aerosol-generating sheet is preferably 0.2-0.6 mg/mm³. If the density is below this lower limit value, the strength of the sheet will be inadequate. Furthermore, if the density exceeds the upper limit value, there will be a drop in volatilization of components of the aerosol-generating sheet. From this perspective, the density is preferably 0.3-0.55 mg/mm³. The density is obtained from the weight and volume of the sheet.

3) Thickness

The thickness of the aerosol-generating sheet is preferably 0.1-1.0 mm. If the thickness is below this lower limit value, the strength of the sheet will be inadequate. Furthermore, if the thickness exceeds the upper limit value, there will be a drop in volatilization of components of the aerosol-generating sheet.

4) Moisture release rate

The aerosol-generating sheet preferably has a moisture release rate of 0.15 (wt%/sec) or greater. The moisture release rate is measured by the following method.

i) The sheet is heated at 100°C to remove water, and a weight reduction - time curve is acquired from the relationship between weight reduction rate and time. The reduction rate (wt%) is defined by: ((sheet weight before heating - sheet weight after heating)/sheet weight before heating) × 100. The sheet weight before heating is the initial weight of the sheet, and the sheet weight after heating is the sheet weight at the time when the heating time has elapsed.
ii) The moisture release rate is obtained from an initial inclination of the curve. The initial inclination is the inclination in a region of the heating time between 0 and 40 seconds, and in one aspect is obtained by dividing the reduction rate (%) at the time when 40 seconds have elapsed from the start of heating, by the heating time.

When the moisture release rate is in the range above, water rapidly evaporates from the aerosol-generating sheet during preheating (after the start of heating but before the start of smoking). As a result, it is possible to suppress a user's feeling of uncomfortable heat of the smoke during smoking. From this perspective, the moisture release rate is more preferably 0.18 (wt%/sec) or greater. There is no limitation to this upper limit, but in one aspect it is 0.5 (wt%/sec) or less.

5) Structure

The aerosol-generating sheet is preferably porous. The aerosol-generating sheet preferably has a plurality of internally dispersed air bubbles. The equivalent circle diameter of the air bubbles is preferably around 10-200 µm. The equivalent circle diameter of the air bubbles is obtained in the following manner. An aerosol-generating sheet having a width of 5 mm is cut in the thickness direction, and the cut face is imaged using an optical microscope. The cross-sectional image is digitized, and the three longest air bubbles are selected. The areas of the selected air bubbles are obtained, the equivalent circle diameters are calculated, and the average value thereof is taken as the equivalent circle diameter of the air bubbles. The number of cut faces observed is preferably 1-5, and more preferably 2-3. The equivalent circle diameter of the air bubbles in the sheet is preferably obtained by averaging the equivalent circle diameters of the air bubbles obtained for each cut face. Furthermore, the sheet preferably has through-holes penetrating both main faces. The equivalent circle diameter of the through-holes is around 10-400 µm. The equivalent circle diameter of the through-holes is obtained in the following manner. A 5 mm × 5 mm observation region is selected on the main face, and that range is imaged using an optical microscope. The planar image is digitized, and the three longest through-holes are selected. The areas of the selected through-holes are obtained, the equivalent circle diameters are calculated, and the average value thereof is taken as the equivalent circle diameter of the through-holes. The number of observation regions is preferably 1-5, and more preferably 2-3. The equivalent circle diameter of the through-holes in the sheet is preferably obtained by averaging the equivalent circle diameters of the through-holes obtained for each observation region. The number of air bubbles or the number of through-holes is suitably adjusted so that the abovementioned basis weight or density is achieved.
The aerosol-generating sheet may also have surface indentations. These indentations are formed by drying a wet sheet comprising air bubbles. The aerosol-generating sheet may furthermore be surface-processed. Embossing and crimping, etc. may be cited as surface processing.

2. Production method

The aerosol-generating sheet is preferably produced by a method comprising: a step (first step) of stir-foaming abovementioned (A), (B) and (C) to prepare a mixture incorporating air bubbles; and a step (second step) of forming the mixture into a sheet.

(1) First step

(1-1) Preparation of tobacco extract liquid

In this step, the tobacco raw material noted above is extracted to prepare a tobacco extract liquid comprising a tobacco extract active ingredient and a medium. Water is preferably used as the medium. There is no limitation as to the extraction temperature, but it is preferably 60-100°C, and more preferably 70-90°C from the perspective of smoking taste. The extraction time is preferably 20-40 minutes.

(1-2) Mixing

In this step, a mixture is prepared by stir-foaming and mixing the components. Stir-foaming is stirring which is performed to produce bubbles. The stir-foaming may be carried out, for example by using a stirring apparatus such as a feed processor, a homogenizer, a mixer, a kneader, a kneading machine, an extruder, a ball mill, or a refiner. The stir-foaming treatment conditions may be suitably established according to the state of the mixture and the type of mixing device, etc. For example, the rotation speed is preferably set at 1000-25,000 rpm in terms of no-load rotation speed, more preferably 2000-20,000 rpm, and more suitably 5000-15,000 rpm.
The medium is also preferably mixed at this time. Water is preferred as the medium. The solid-liquid ratio (weight ratio) of the mixture is preferably 1:1-1:8. The solid-liquid ratio is the weight ratio of all non-medium components and the medium. The non-medium components also include substances which are liquid at normal temperature (e.g., glycerol, etc.), but the weight ratio of all non-medium components and the medium will be referred to as the "solid-liquid ratio" for simplicity in the present disclosure. Furthermore, the weight of the non-medium components is the dry weight (dry basis). If the solid-liquid ratio is below the range above, the water content is low and the mixture therefore dries at an early stage of a drying step, and air bubbles, through-holes and indentations are not readily formed. A reduction in flavor components can be suppressed as a result. From this perspective, the solid-liquid ratio (weight ratio) is more preferably 1:2-1:6. The weight ratios (C)/(B) and (B)/(D) of the mixture preferably satisfy the range above. The viscosity of the mixture is preferably 10,000-100,000 mPa·s. Setting the viscosity in the range above enables stir-foaming to be suitably performed.

(2) Step 2

A sheet can be formed by using a casting method. In the casting method, the mixture is cast onto a substrate and a wet sheet is formed The wet sheet is then dried to obtain a sheet. The drying temperature is preferably 50-100°C. The sheet obtained by the casting method is also referred to as a "cast sheet".

3. Flavor-generating composition

(1) Constitution

The flavor-generating composition comprises the aerosol-generating sheet or a material derived therefrom. The flavor-generating composition may furthermore comprise the aerosol-generating sheet and leaf tobacco. Here, a blending ratio (weight) of the aerosol-generating sheet and the leaf tobacco may be aerosol-generating sheet : leaf tobacco = 40-80:20-60. Setting the blending ratio of the aerosol-generating sheet and the leaf tobacco in the range above makes it possible to reduce the fiber odor and to improve the extent and persistence of flavor, while also ensuring a sufficient amount of smoke.

(2) Leaf tobacco

1) Definition

"Leaf tobacco" as referred to in the present specification includes harvested tobacco leaves; harvested tobacco leaves which have been de-stemmed and separated into lamina and midrib; aged leaf tobacco which has passed through aging (including curing); and cut tobacco obtained by cutting aged leaf tobacco, etc. to a predetermined size.

2) Tobacco varieties

A number of tobacco varieties may be used. Examples that may be cited include Yellow, Burley, Oriental, or native type, and other Nicotiana tabacum and Nicotiana rustica varieties. These varieties can be used alone, but in order to obtain the intended flavor, they can also be blended for use over the course of the process from harvesting of leaf tobacco until the aged leaf tobacco is made into cut tobacco. Details on tobacco varieties are disclosed in "Encyclopedia of Tobacco, Tobacco Academic Studies Center, March 31, 2009".

3) Cut tobacco from leaf tobacco

The leaf tobacco may be cut tobacco from leaf tobacco (also referred to below as "cut leaf tobacco"). Cut leaf tobacco is obtained by cutting aged leaf tobacco, etc. to a predetermined size. There is no particular limitation as to the aged leaf tobacco which is used for the cut leaf tobacco, and aged leaf tobacco which has been de-stemmed and separated into lamina and midrib may be cited.

4) Method of preparing cut leaf tobacco

There is no particular limitation as to the size and method of preparation of the cut leaf tobacco. As an example which may be cited, aged leaf tobacco is cut to a width of 0.3 mm-2.0 mm, and a length of 3 mm-30 mm. When considered as a flavor-generating source, various cut widths can be set while taking account of thermal conductivity, etc. Cut tobacco of such a size is preferable for filling a wrapper which will be described later. Furthermore, two or more types of leaf tobacco having different cut widths within the range of 0.3-2.0 mm are preferably used from the perspective of allowing a wide range of puff timings over which the extent of the flavor is experienced. For example, it is possible to use first leaf tobacco having a cut width of 0.3-1.2 mm, and second leaf tobacco having a cut width of 0.8-1.7 mm (with the second leaf tobacco having a greater cut width than the first leaf tobacco). Reducing the cut width increases the surface area per unit mass and increases thermal conduction efficiency. Increasing the thermal conduction efficiency allows the tobacco filling material to be heated in a short time. Meanwhile, increasing the cut width reduces the surface area per unit mass and reduces thermal conduction efficiency, which therefore allows the tobacco filling material to be heated over a long period of time.

4. Smoking article

The aerosol-generating sheet of this embodiment is useful as a flavor source (filling material) for combustible smoking articles and heat-not-burn smoking articles, and is suitable for heat-not-burn smoking articles. Fig. 3 shows an embodiment of a heat-not-burn smoking article. As shown in the drawing, a heat-not-burn smoking article 20 comprises: a tobacco segment 20A, a cylindrical cooling portion 20B having a circumferential perforation, and a filter portion 20C. The heat-not-burn smoking article 20 may comprise members other than these. There is no limitation as to the axial length of the heat-not-burn smoking article 20, but it is preferably 40-90 mm, more preferably 50-75 mm, and even more preferably 50-60 mm. Furthermore, the circumferential length of the heat-not-burn smoking article 20 is preferably 16-25 mm, more preferably 20-24 mm, and even more preferably 21-23 mm. In an exemplary mode that may be cited, the length of the tobacco segment 20A is 20 mm, the length of the cooling portion 20B is 20 mm, and the length of the filter portion 20C is 7 mm. The lengths of the individual members can be modified as appropriate, depending on manufacturability and required quality, etc. Fig. 3 shows a mode in which a first segment 25 is provided, but this need not be provided, and only a second segment 26 may be arranged downstream of the cooling portion 20B.

1) Tobacco segment 20A

A tobacco filling material 21 in the tobacco segment 20A comprises the aerosol-generating sheet or a flavor-generating composition containing same. There is no particular limitation as to the method of filling a wrapper 22 with the aerosol-generating sheet, but the aerosol-generating sheet may be enclosed in the wrapper 22, or a cylindrical wrapper 22 may be filled with a folded aerosol-generating sheet, etc. When the aerosol-generating sheet is used in the form of strands, the wrapper 22 may be filled with the strands in such a way that the strands have random longitudinal directions, or in such a way that the strands are aligned with the axial direction of the tobacco segment 20A or a direction orthogonal thereto. Furthermore, the aerosol-generating sheet may used in the form of cuts. The tobacco segment 20A is heated to thereby vaporize the tobacco component, aerosol source and water contained in the tobacco filling material 21, and these components are then ready to be inhaled.
When the aerosol-generating sheet is in the form of strands or cuts, there is no particular restriction on the size or method of preparation of the strands or cuts. As an example which may be cited, the aerosol-generating sheet may be processed so that the strands or cuts have a width of 0.3-2.0 mm. The strands and cuts of the aerosol-generating sheet having such a size are suitable for filling the wrapper. Furthermore, the width of the strands and a substrate of the aerosol-generating sheet is preferably 0.3-1.0 mm from the perspective of being able to suppress a delay in the intrinsic flavor of the tobacco sheet being demonstrated. In addition, when the aerosol-generating sheet is considered not only as a vapor source but also as a hydrophilic flavor-generating source, various cut widths are preferably set while taking account of thermal conductivity, etc. Furthermore, when the aerosol-generating sheet is processed into strands, the length thereof is preferably 3 mm-30 mm.
The packing density of the aerosol-generating sheet or the flavor-generating composition in the tobacco filling material 21 is preferably 0.25-0.60 g/cm³. An adequate wrapping hardness can be ensured when the packing density is 0.25 g/cm³ or greater. Furthermore, when the packing density is 0.60 g/cm³ or less, it is possible to reduce the filling amount of the aerosol-generating sheet or the flavor-generating composition, therefore enabling a reduction in production costs.

2) Cooling portion 20B

The cooling portion 20B is preferably formed by a cylindrical member. The cylindrical member may be a paper tube 23 obtained by processing cardboard into a cylindrical shape, for example. Furthermore, the cooling portion 20B may also be formed by a sheet of a thin material that is creased and then pleated, gathered, or folded to form channels. Examples of such materials that can be used include sheet materials selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polylactic acid, cellulose acetate, and aluminum foil. The total surface area of the cooling portion 20B is prepared, as appropriate, taking cooling efficiency into account, and may for example be 300-1000 mm²/mm. The cooling portion 20B is preferably provided with a perforation 24. The perforation 24 allows external air to be introduced into the cooling portion 20B during drawing. As a result, the aerosol vaporized component generated by heating of the tobacco segment 20A is liquefied because it comes into contact with the external air so that the temperature thereof decreases, and an aerosol is formed. There is no particular limitation as to the diameter (length across) of the perforation 24, and it may be 0.5-1.5 mm, for example. There is no particular limitation as to the number of perforations 24 and there may be one, or two or more. For example, multiple perforations 24 may be provided on the circumference of the cooling portion 20B.
The cooling portion 20B may be formed into a rod shape having an axial length of 7-28 mm, for example. The axial length of the cooling portion 20B may be 18 mm, for example. The cooling portion 20B may have a substantially circular axial cross-sectional shape, which can be 5-10 mm in diameter. The cooling portion can be approximately 7 mm in diameter, for example.

3) Filter portion 20C

There is no particular limitation as to the configuration of the filter portion 20C, but it may be formed from a single filling layer or multiple filling layers. The outside of the filling layer may be wrapped with a single or multiple wrapping papers. The airflow resistance of the filter portion 20C may be modified, as appropriate, by the amount and material, etc. of the filter filling material with which the filter portion 20C is filled, for example. For example, when the filter filling material is cellulose acetate fibers, an increase in the amount of cellulose acetate fibers with which the filter portion 20C is filled can cause increased airflow resistance. When the filter filling material is cellulose acetate fibers, the packing density of cellulose acetate fibers may be 0.13-0.18 g/cm³. The airflow resistance is a value measured by means of an airflow resistance measurement gauge (trade name: SODIMAX, manufactured by SODIM).
There is no particular limitation as to the circumferential length of the filter portion 20C, but it is preferably 16-25 mm, more preferably 20-24 mm, and even more preferably 21-23 mm. The axial length (horizontal direction in the drawing) of the filter portion 20C may be selected at 4-10 mm, and this length is selected to achieve an airflow resistance of 15-60 mmH₂O per segment. The axial length of the filter portion 20C is preferably 5-9 mm, and more preferably 6-8 mm. There is no particular limitation as to the cross-sectional shape of the filter portion 20C, and it may be circular, elliptical, or polygonal, etc., for example. Furthermore, a breakable capsule comprising a flavoring material, flavor beads, or a flavoring material may be directly added to the filter portion 20C.
The filter portion 20C may comprise a center hole portion as the first segment 25. The center hole portion may comprise a first filling layer 25a having one or more hollow portions, and an inner plug wrapper (inside wrapping paper) 25b that covers said filling layer. The center hole portion has the function of strengthening a mouthpiece portion. The shape of the center hole portion may be retained by means of thermoforming, without an inner plug wrapper 25b being provided. The filter portion 20C may comprise a second segment 26. The second segment 26 comprises a second filling layer 26a and an inner plug wrapper (inside wrapping paper) 26b that covers said filling layer. The second filling layer 26a may be formed, for example, as a rod having an inner diameter of φ5.0 mm-φ1.0 mm packed with a high density of cellulose acetate fibers, a plasticizer comprising triacetin being added thereto in an amount of 6-20 mass%, in relation to the mass of cellulose acetate, and the plasticizer being cured. The second filling layer has a high packing density of fibers, so the air and aerosol flow only through the hollow portion during drawing, with virtually none flowing through the filling layer. The second filling layer inside the center hole portion is a fiber filled layer, and the user will therefore have little sense of incongruity when touching the outside during use.
The first filling layer 25a and the second filling layer 26a are connected by an outer plug wrapper (outside wrapping paper) 27. The outer plug wrapper 27 may be paper in a cylindrical shape, for example. Furthermore, the tobacco segment 20A, the cooling portion 20B, and the connected first filling layer 25a and second filling layer 26a are connected by means of a mouthpiece lining paper 28. These connections may be formed, for example, by coating an inside surface of the mouthpiece lining paper 28 with a glue such as a vinyl acetate-based glue, and wrapping the abovementioned three members. These members may also be connected by multiple separate connections with multiple lining papers.
A combination of a heat-not-burn smoking article and a heating device for generating an aerosol also refers especially to a heat-not-burn smoking system. An example of such a system is shown in fig. 4. The heat-not-burn smoking system in the drawing comprises the heat-not-burn smoking article 20 and a heating device 10 for heating the tobacco segment 20A from the outside.
The heating device 10 comprises a body 11, a heater 12, a metal tube 13, a battery unit 14, and a control unit 15. The body 11 has a cylindrical recess 16, where the heater 12 and metal tube 13 are disposed at positions facing the smoking segment 20A which is inserted into the recess 16. The heater 12 may be a heater employing electrical resistance, with electrical power being supplied by the battery unit 14 in accordance with a command from the control unit 15 which controls the temperature, such that heating is effected by the heater 12. Heat emitted from the heater 12 is transferred to the tobacco segment 20A through the highly thermally conductive metal tube 13. The drawing shows a mode in which the heating device 10 heats the tobacco segment 20A from the outside, but it may equally be heated from the inside. There is no particular limitation as to the heating temperature produced by the heating device 10, and it is preferably 400°C or less, more preferably 150-400°C, and even more preferably 200-350°C. The heating temperature refers to the temperature of the heater of the heating device 10. Furthermore, it is also possible to provide a susceptor inside the tobacco segment 20A in order to heat the tobacco segment 20A by an IH method.
Embodiments are disclosed below.

Aspect 1

An aerosol-generating sheet comprising: (A) 15-50 wt% of a tobacco extract;

Aspect 2

The sheet as disclosed in aspect 1, wherein the density is 0.2-0.6 mg/mm³.

Aspect 3

Aspect 4

Aspect 5

Aspect 6

Aspect 7

Aspect 8

Aspect 9

Aspect 10

Aspect 11

Aspect 12

Aspect 13

A method for producing the aerosol-generating sheet as disclosed in any of aspects 1 to 9, comprising: a step of foaming abovementioned (A), (B) and (C) with stirring to prepare a mixture incorporating air bubbles; and a step of forming the mixture into a sheet.

Aspect 14

EXAMPLES

EXAMPLE 1

Water was added to leaf tobacco of the Oriental variety (Izmir variety), extraction was performed for 1 hour at 80°C, and a tobacco extract liquid (Izmir-water extract liquid) was obtained. In this process, the amount of water added was an amount such that (amount of moisture contained in tobacco leaf + amount of water added)/tobacco leaf dry weight = 5. Specifically, the amount of water was 4.3 times the weight of leaf tobacco on a wet basis. Water was added to leaf tobacco of the Yellow variety produced in Brazil, extraction was performed for 1 hour at room temperature, and a tobacco extract liquid (BRFCV-water extract liquid) was obtained. In this process, the amount of water which was added was an amount such that (amount of moisture contained in tobacco leaf + amount of water added)/tobacco leaf dry weight = 5. Specifically, the amount of water was 4.3 times the weight of leaf tobacco on a wet basis.
Hydroxypropyl methylcellulose (METOLOSE N-100, manufactured by Shin-Etsu Chemical Co., Ltd.), and carboxymethyl cellulose (F350HC, manufactured by Nippon Paper Industries Co., Ltd.) were prepared as a binder. Dietary fiber of citrus origin (HERBACEL, manufactured by Sumitomo Pharma Food & Chemical Co., Ltd.) was prepared as fiber. Glycerol was prepared as an aerosol source.
A mixture (slurry) incorporating air bubbles was prepared by stir-foaming the components above under the following conditions using the compositions shown in Table 1. "%" in the table means weight percentage.

Model number: AHG-160A (AS ONE Corp.)
Shaft generator used: HT1018
Capacity: 50 g
Rotation speed: 10,000 rpm
Treatment time: 10 minutes
Temperature: 20°C (normal temperature)

The slurry was then cast onto a stainless steel plate to a thickness of 1.5 mm and dried at 80°C to produce a porous aerosol-generating sheet. The basis weight was 0.16 mg/mm², the thickness was 0.3 mm, and the density was 0.5 mg/mm³.

EXAMPLE 2

An aerosol-generating sheet was prepared by the same method as in Example 1, except that the composition was changed as shown in Table 1.

COMPARATIVE EXAMPLE 1

The composition shown in Table 1 was mixed to prepare a wet powder (mixture) having a moisture content of 20.30 wt%. The wet powder was placed between two substrates and rolled out using rolling rolls (manufactured by Yuri Roll Machine Co., Ltd.). The substrates were detached and the wet sheet was dried at 80°C to prepare a laminated sheet. The basis weight was 0.37 mg/mm², the thickness was 0.3 mm, and the density was 1.2 mg/mm³.

[Table 1]

(%- DB)		COMPARATIVE EXAMPLE 1	EXAMPLE 1	EXAMPLE 2
(A) Tobacco extract	Izmir-water extract liquid	15%,	16%	15%
(A) Tobacco extract	BRFCV-water extract liquid	25%	26%	25%
(B) Binder	METOLOSE N-100(HPMC)	0%	6%	6%
(B) Binder	CMC F350HC	5%	6%	6%
(C) Aerosol source	Glycerol	35%	35%	33%
(D) Fiber	HERBACEL	20%	11%	15%
(C) / (B)		7.0	2.9	2.8
(B) / (D)		0.25	1.09	0.78
Wet powder moisture		20.3%
Solid/liquid ratio			1:4	1:4
Basis weight [mg/mm²]		0.37	0.16	0.12
Thickness [mm]		0.3	0.3	0.3
Density [mg/mm³]		1.2	0.5	0.4

DB: Dry basis

Measurement of rate of volatilization of components from the sheet

The sheets shown in Table 2 were heated at 200°C using an IR moisture meter and the change in weight of the sheets was measured. The reduction rate was determined as follows. $Reduction rate (wt %) = ((sheet weight before heating - sheet weight after heating) / sheet weight before heating) \times 100$

The heat irradiation area is the area of the sample facing the IR moisture meter (heater).

[Table 2]

Table 2: Sheet shape, etc.
No.	Sheet type	Size [mm]	Heat irradiation area [mm²]	Number of layers*	Weight [g]
1	Comparative Example 1	52*52	2704	1	1.0
2	Example 2	52*52	2704	1	0.3
3	Example 2	52*52	2704	3	1.0

*A stack in the thickness direction was used where there were multiple layers

The results are shown in fig. 1.

It is clear from a comparison of No. 1 and No. 2 that, for the same volume, a porous sheet has a greater weight reduction rate. It was confirmed from this that the sheet of No. 2 has higher volatilization of components from the sheet than the sheet of No. 1.
A comparison of No. 1 and No. 3 showed that, for the same weight, a porous sheet has a greater weight reduction rate. However, it is clear that the difference is smaller than when the volumes are the same. It was furthermore confirmed that although the sheet of No. 3 is thicker than the sheet of No. 1, there is higher volatilization of components from the sheet of No. 3.

Measurement of rate of moisture release from the sheet

The sheets of No. 1 and No. 2 were heated at 100°C using an IR moisture meter, the change in weight of the sheets was measured, and the moisture release rate was calculated. The reduction rate was determined as follows. $Reduction rate (wt %) = ((sheet weight before heating - sheet weight after heating) / sheet weight before heating) \times 100$
The results are shown in Table 3 and fig. 2. [Table 3]

No. Reduction rate [wt%] at time when heating time reached 40 seconds Moisture release rate [wt%/sec]

1 5.7% 0.14

2 9.6% 0.24
Water is a component which volatilizes at 100°C, and these results therefore show the rate of volatilization of water. It was clear that the sheet of No. 2 has a greater rate of volatilization of water. The moisture volatilizes from the sheet at an early stage, and heat of the smoke can therefore be reduced. That is to say, moisture volatilizes during preheating of a heated smoking article, and the heat of the smoke can therefore be reduced.

REFERENCE SIGNS LIST

10 Heating device
11 Body
12 Heater
13 Metal tube
14 Battery unit
15 Control unit
16 Recess
17 Ventilation hole
20 Heat-not-burn smoking article
20A Tobacco segment
20B Cooling portion
20C Filter portion
21 Tobacco filling material
22 Wrapping paper
23 Paper tube
24 Perforation
25 First segment
25a First filling layer
25b Inner plug wrapper
26 Second segment
26a Second filling layer
26b Inner plug wrapper
27 Outer plug wrapper
28 Lining paper

Claims

An aerosol-generating sheet comprising: (A) 15-50 wt% of a tobacco extract;
(B) 6-20 wt% of a binder; and

(C) 15-60 wt% of an aerosol source, wherein the basis weight of the aerosol-generating sheet is 0.10-0.25 mg/mm².
The sheet as claimed in claim 1, wherein the density is 0.2-0.6 mg/mm³.
The sheet as claimed in claim 1 or 2, internally comprising a plurality of dispersed air bubbles, or having through-holes penetrating both main faces.
The sheet as claimed in any of claims 1 to 3, wherein the binder is selected from the group consisting of: cellulose derivatives, xanthan gum, guar gum, carrageenan, locust bean gum, alginic acid, sodium alginate, starch, soluble soybean polysaccharide, and combinations thereof.
The sheet as claimed in claim 4, wherein the cellulose derivatives include hydroxyalkyl alkyl cellulose, carboxyalkyl cellulose, or alkyl cellulose.
The sheet as claimed in claim 5, wherein the cellulose derivatives include hydroxypropyl methylcellulose (HPMC) and carboxymethyl cellulose (CMC), a weight ratio of HPMC and CC being 0.5:1-2:1.
The aerosol-generating sheet as claimed in any of claims 1 to 6, further comprising: (D) fiber, wherein a weight ratio of the binder (B) and fiber (D) component satisfies: 0.30≤(B)/(D)≤1.2.
The aerosol-generating sheet as claimed in any of claims 1 to 7, wherein a weight ratio of the aerosol source (C) and the binder (B) satisfies: 2.0≤(C)/(B)≤4.0.
The aerosol-generating sheet as claimed in any of claims 1 to 8, wherein a moisture release rate is 0.15 (wt%/sec) or greater, the moisture release rate being obtained by the following method: 1) the sheet is heated at 100°C to remove water, and a weight reduction - time curve is acquired from the relationship between a weight reduction rate and time; and
2) the moisture release rate is obtained from an initial inclination of the curve.
A flavor-generating composition comprising the aerosol-generating sheet as claimed in any of claims 1 to 9, and leaf tobacco.
A heat-not-burn smoking article comprising a tobacco segment which includes the aerosol-generating sheet as claimed in any of claims 1 to 9, or the flavor-generating composition as claimed in claim 10.
A heat-not-burn smoking system comprising the heat-not-burn smoking article as claimed in claim 11, and a heating device.
A method for producing the aerosol-generating sheet as claimed in any of claims 1 to 9, comprising: a step of stir-foaming abovementioned (A), (B) and (C) to prepare a mixture incorporating air bubbles; and
a step of forming the mixture into a sheet.
The production method as claimed in claim 13, wherein a solid/liquid ratio of the mixture is 1:1-1:8, and a weight ratio (C)/(B) of the mixture satisfies: 2.0≤(C)/(B)≤4.0.