EP4678016A1 - Aerosol generating sheet - Google Patents

Abstract

A method for producing an aerosol-generating sheet containing a tobacco extract E and other ingredient(s) B, said method comprising:
(1) a step of preparing a mixture that contains the tobacco extract E and other ingredient(s) B, and that satisfies the following relationship: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{mixture}/\mathrm{weight}\mathrm{of}\mathrm{non}-\mathrm{water}\mathrm{ingredients}\mathrm{in}\mathrm{mixture}\ge 3$$ and (2) a step of obtaining a sheet from the mixture.

Description

TECHNICAL FIELD
• The present invention relates to an aerosol-generating sheet.
BACKGROUND ART
• Aerosol-generating sheets serve as a flavor source in smoking articles. PTL 1 and 2 disclose aerosol-generating sheets in which a tobacco extract is used as the tobacco-derived material.
CITATION LIST PATENT LITERATURE
• [PTL 1] JP 6695359 B2
• [PTL 2] JP 5248486 B2
SUMMARY OF INVENTION TECHNICAL PROBLEM
• When a sheet is produced using a tobacco extract as disclosed in PTL 1 and 2, the composition for the sheet must be concentrated. Producing a sheet without concentrating the sheet composition can make the production process more efficient. In view of the above circumstances, an object of the present invention is to provide a more efficient method for producing an aerosol-generating sheet.
SOLUTION TO PROBLEM
• The inventors solved the problem by ensuring that the liquid-solid ratio, defined as "the weight of water in a mixture/weight of non-water ingredients in the mixture" is at least a predetermined value. Specifically, the above problem is solved by the following invention:
• Aspect 1 A method for producing an aerosol-generating sheet containing a tobacco extract E and other ingredient(s) B, said method comprising:
  1. (1) a step of preparing a mixture that contains the tobacco extract E and other ingredient(s) B, and that satisfies the following relationship: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{mixture}/\mathrm{weight}\mathrm{of}\mathrm{non}-\mathrm{water}\mathrm{ingredients}\mathrm{in}\mathrm{mixture}\ge 3$$ and (2) a step of obtaining a sheet from the mixture.
• Aspect 2 The production method according to aspect 1, wherein step (1) comprises:
  • (1-1) a step of preliminarily extracting the tobacco raw material with water to obtain a tobacco extract liquid L comprising the tobacco extract E and water, and determining an extraction rate a defined by the following equation (1): $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}=\mathrm{Ed}\left(\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
  • (1-2) a step of determining X relating to the weight of water used for further extraction by the same method as step (1-1), based on equation (I) below: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$ (here, $$\mathrm{liquid}-\mathrm{solid}\mathrm{ratio}\ge 3$$ $$\mathrm{X}=\mathrm{Ew}\left(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{L}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
    • Bw: total weight of water in all ingredients B
    • Bd: total dry weight of all ingredients B $$\mathrm{t}=\mathrm{proportion}\mathrm{of}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{used}=\mathrm{Ed}/\left.\left(\mathrm{Ed}+\mathrm{Bd}\right)\right)$$
  • (1-3) a step of extracting the tobacco raw material using water in an amount that satisfies X above to obtain a tobacco extract liquid; and
  • (1-4) a step of mixing the tobacco extract liquid obtained in step (1-3) above with the other ingredient(s) to prepare a mixture that satisfies equation (I).
• Aspect 3 The production method according to aspect 1, wherein step (1) comprises:
  • (1-1) a step of preliminarily extracting the tobacco raw material with a solvent mixture comprising water and alcohol to obtain a tobacco extract liquid L' comprising the tobacco extract E, water, and alcohol, and determining an extraction rate a' defined by the following equation (1'): $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}\prime =\mathrm{Ed}\left(\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
  • (1-2) a step of determining X relating to the weight of water used for further extraction by the same method as step (1-1), based on equation (I') below: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\prime \right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$ (here, $$\mathrm{liquid}-\mathrm{solid}\mathrm{ratio}\ge 3$$ $$\mathrm{X}=\mathrm{Ew}\left(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{L}\prime \right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
    • Bw: total weight of water in all ingredients B
    • Bd: total dry weight of all ingredients B $$\mathrm{t}=\mathrm{proportion}\mathrm{of}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{used}=\mathrm{Ed}/\left(\mathrm{Ed}+\mathrm{Bd}\right)$$
  • (1-3) a step of determining the amount of the solvent mixture used for the further extraction based on the weight ratio X, and extracting the tobacco raw material using that amount of solvent mixture to obtain a tobacco extract liquid; and (1-4) a step of mixing the tobacco extract liquid obtained in step (1-3) above with the other ingredient(s) to prepare a mixture that satisfies equation (I').
• Aspect 4 The production method according to any of aspects 1 through 3, wherein the content of the tobacco extract in the aerosol-generating sheet is 15 to 50% by weight based on dry weight.
• Aspect 5 The production method according to any of aspects 1 through 4, wherein the other ingredient(s) B comprise an aerosol source, and
  the content of the aerosol source in the aerosol-generating sheet is 10 to 60% by weight based on dry weight.
• Aspect 6 The production method according to any of aspects 1 through 5, wherein the other ingredient(s) comprise non-wood fiber, wood fiber, or a binder.
• Aspect 7 The production method according to aspect 6, wherein the non-wood fiber is dietary fiber.
• Aspect 8 The production method according to aspect 7, wherein the non-wood fiber is citrus fiber.
• Aspect 9 The production method according to any of aspects 6 through 8, wherein the binder is carboxyalkyl cellulose or guar gum.
• Aspect 10 The production method according to any of aspects 6 through 9, wherein the wood fiber content is lower than the non-wood fiber content.
ADVANTAGEOUS EFFECTS OF INVENTION
• The present invention allows a more efficient method for producing an aerosol generating sheet to be provided.
DESCRIPTION OF EMBODIMENTS
• As used in the present disclosure, the range "X-Y" includes X and Y as the end values. Dry weight is the weight excluding the weight of water.
1. Production Method
• The method for producing an aerosol-generating sheet containing a tobacco extract E and other ingredient(s) B in one embodiment comprises: (1) a step of preparing a mixture that contains the tobacco extract E and other ingredient(s) B at a specific liquid-solid ratio; and (2) a step of obtaining a sheet from the mixture.
(1) Step (1): Step for preparing mixture
• In the present step, a mixture that comprises a tobacco extract E and other ingredient(s) B and that satisfies the following relationship is prepared. $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{mixture}/\mathrm{weight}\mathrm{of}\mathrm{non}-\mathrm{water}\mathrm{ingredients}\mathrm{in}\mathrm{mixture}\ge 3$$
• The sheet will be difficult to prepare if the liquid-solid ratio is less than 3. On the other hand, too high of an upper limit will result in a sheet containing less of the active ingredients. In that respect, the upper limit of the liquid-solid ratio is preferably 8 or less, and more preferably 5 or less. Mixtures having a liquid-solid ratio within this range can be provided to the sheet-producing process without being concentrated. Loss of flavor components can therefore be curtailed. Substances that are liquids at ambient temperature are also present in "non-water ingredients in the mixture," but the liquid-solid ratio is defined as noted above for the sake of convenience in the present disclosure.
• The type of sheet that is obtained will vary, depending on the amounts of the ingredients included in the mixture. The liquid-solid ratio is preferably 3 to 5, for example, in types where the tobacco extract E dry weight in the mixture is greater than the aerosol source dry weight (also referred to below as "tobacco-rich types"). In these types, the tobacco extract E dry weight/mixture dry weight ratio is preferably 15 to 50% by weight. The liquid-solid ratio is also preferably 3 to 5 in types where the aerosol source dry weight in the mixture is greater than the tobacco extract E dry weight (also referred to below as "aerosol source-rich types"). In these types, the aerosol source dry weight/mixture dry weight ratio is preferably 40 to 60% by weight.
1) Tobacco extract
• The tobacco extract E is a flavoring or mixture that is extracted from tobacco. The tobacco extract can be prepared by known methods. Examples of media used for extraction include water or hydrophilic organic solvents such as alcohol. In one aspect, the medium is water (this embodiment is also referred to as "water extraction"), and in another embodiment, the medium is a media mixture of water and alcohol (this embodiment is also referred to as "solvent extraction"). Examples of alcohols include polyhydric alcohols, such as propylene glycol and glycerol, and monoalcohols, such as ethanol. The alcohol is preferably an aerosol source noted below.
• Examples of methods of extraction include: 1) methods in which a tobacco raw material is extracted using a medium to obtain a tobacco extract; 2) methods in which a medium is added to a tobacco raw material, the mixture is heated, and the vapor that is generated is collected; and 3) methods in which a heat-vaporized medium is allowed to pass through a tobacco raw material, and the vapor that has passed through is collected. In the methods of 1), water extraction is preferred in the interests of workability, for example. Solvent extraction is preferred in the methods of 2) and 3) in the interests of work efficiency. Acids or alkalis can also be used, as needed, for extraction. The liquid containing the tobacco extract E and medium that is obtained via extraction is called the tobacco extract liquid L.
• Raw materials of the Nicotiana genus, such as Nicotiana tabacum and Nicotiana rustica, can be used as the tobacco raw material. 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 shredded 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 to 1.18 mm. Such raw material pieces are obtained via sifting in accordance with JIS Z 8815 using a stainless steel sieve per JIS Z 8801, for example. For example, 1) raw material pieces are sifted over a 20-minute period by means of drying and 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 drying and 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 said treatment are collected to prepare a tobacco extract liquid L comprising the tobacco extract E and water. At that time, the flavor components are preferably extracted in the form of gas from the alkaline-treated tobacco raw material, and the gas is preferably introduced into water to thereby transfer the flavor components into a liquid
• The alkaline substance is preferably an alkaline liquid such as potassium carbonate aqueous solution. At that time, the alkaline substance is supplied until the pH of the tobacco raw material is within a certain range. The pH is preferably at least 8.0, and more preferably 8.9 to 9.7. The pH of the tobacco raw material is 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 is not limited but is preferably about 5 to 30% by weight 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 weight loss that has occurred at the point in time when a 1 g sample has been heated to 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, by OHAUS CORPORATION).
• Too little an amount of the tobacco extract E will result in poor smoking flavor, and too much may result in a loss of sheet strength. In this respect, the lower limit of the tobacco extract E dry weight/mixture dry weight ratio is preferably 10% by weight or more, 15% by weight or more, or 20% by weight or more. The upper limit is preferably 60% by weight or less, 50% by weight or less, or 40% by weight or less. For tobacco-rich types in particular, the ratio is preferably 20 to 50% by weight. For aerosol source-rich types, the ratio is preferably 10 to 40% by weight. In the present embodiment, the amount of each ingredient in the mixture on a dry basis (dry weight of each ingredient/mixture dry weight) is equal to the amount of each ingredient in the sheet on a dry basis (dry weight of each ingredient/sheet dry weight).
2) Other ingredient(s) B 2-2) Aerosol source
• Examples of aerosol sources include polyhydric alcohols such as glycerol or propylene glycol. The moisture content of the aerosol source can be determined by a known method, and can be determined, for example, in the same manner as the moisture content of the tobacco raw material. Too little an amount of the aerosol source will result in insufficient smoke volume during smoking. Too great an amount will result in poor sheet handling. In this respect, the lower limit of the aerosol dry weight/mixture dry weight ratio is preferably 5% by weight or more, 10% by weight or more, 20% by weight or more, or 40% by weight or more. The upper limit is preferably 70% by weight or less, 60% by weight or less, 50% by weight or less, or 40% by weight or less. For aerosol source-rich types in particular, the ratio is preferably 40 to 60% by weight. For tobacco-rich types, the ratio is preferably 10 to 40% by weight, and more preferably 20 to 40% by weight.
2-3) Non-wood fiber
• Non-wood fiber is fiber that is not derived from wood, and is preferably fiber other than tobacco fiber. Tobacco fiber is unlikely to make the sheet stronger, and may result in a harsh taste. 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, specifically, may be sponge-like. Porous fiber can increase the surface area of the sheet for a smoking article, and can enhance the thermal conductivity of the sheet. The fiber is preferably citrus fiber, because it is readily available, for example. 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 make the sheet stronger. The moisture content of the non-wood fiber can be determined by a known method, and can be determined, for example, in the same manner as the moisture content of the tobacco raw material. In one aspect, the non-wood fiber dry weight/mixture dry weight ratio is 10 to 40% by weight or 10 to 30% by weight.
2-4) Wood fiber
• Wood fiber can be used as the other ingredient(s). Examples of wood fiber include softwood pulp, Vitacel FL400, and Vitacel L600/30 (both by J. Rettenmaier & Sohne GmbH). The moisture content of the wood fiber is determined in order to decide how much wood fiber should be blended so as to satisfy the above relationship. The moisture content of the wood fiber can be determined by a known method, and can be determined. for example, in the same manner as the moisture content of the tobacco raw material. In one aspect, the wood fiber dry weight mixture dry weight ratio is 1 to 10% by weight. When both wood fiber and non-wood fiber are present, the wood fiber content is preferably lower than the non-wood fiber content.
2-5) Binder
• A binder can be used as the other ingredient(s). Examples of binders include carboxyalkyl cellulose and guar gum. The moisture content of the binder is determined in order to decide how much binder should be blended so as to satisfy the above relationship. The moisture content of the binder can be determined by a known method, and can be determined, for example, in the same manner as the moisture content of the tobacco raw material. In one aspect, the binder dry weight/mixture dry weight ratio is 1 to 10% by weight.
2-6) Flavoring
• Examples of flavoring include, but are not limited to, menthols, and any of the following can be used. The amount of flavoring may also be a known amount. These examples of flavoring may be used alone, or in combinations of two or more.
• The following are examples of preferred flavoring: 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, cedarwood 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, ethyl 2-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, sodium 4-hydroxyundecanoate, immortelle absolute, β-ionone, isoamyl acetate, isoamyl butyrate, isoamyl phenylacetate, isobutyl acetate, isobutyl phenylacetate, jasmine absolute, kola nut tincture, labdanum oil, terpeneless lemon oil, glycyrrhiza extract, linalool, linalyl acetate, lovage root oil, maltol, maple syrup, menthol, menthone, L-menthyl acetate, para-methoxy benzaldehyde, 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-cyclohexene-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, veratric aldehyde, violet leaf absolute, N-ethyl-p-menthane-3-carboxamide (WS-3), and ethyl-2-(p-menthane-3-carboxamide) acetate (WS-5).
3) Preferred aspects Water extraction
• Step (1) preferably comprises the following steps (1-1) through (1-4).
Step (1-1)
• In this step, the tobacco raw material is preliminarily extracted with water, and the extraction rate a defined by the following equation (1) is determined. $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}=\mathrm{Ed}\left(\mathrm{tobacco}\mathrm{extract}\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
• Dry weight is the weight excluding water. Ed (tobacco extract E dry weight) is thus the dry weight of the tobacco extract liquid L obtained via extraction, specifically, the weight of the tobacco extract liquid L minus the weight of the water.
• Extraction can be effected by a known method. The extraction temperature is not limited, but is preferably 60 to 100°C, and more preferably 70 to 90°C, in the interests of smoking flavor. The extraction time is preferably 20 to 40 minutes.
Step (1-2)
• In this step, factor X relating to the weight of water used for further extraction is determined based on equation (I). The liquid-solid ratio is determined so as to satisfy said range. $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$
• X is defined as Ew (weight of water in tobacco extract liquid L)/Td (tobacco raw material dry weight). Specifically, X is the ratio of the weight of the water used for extraction relative to the dry weight of the tobacco raw material.
• Bw is the total weight of water in all ingredients B in the mixture obtained in step 1-4. All ingredients B means all ingredients other than the tobacco extract, and refers, for example, to the total of the aerosol source and fiber, etc. Bd is the total dry weight of all ingredients B in the mixture obtained in step 1-4. Bw and Bd are obtained by analyzing the ingredients by known methods.
• The symbol t is defined as the proportion of tobacco extract liquid used: Ed/(Ed + Bd). Specifically, t is the [tobacco extract E dry weight/mixture dry weight] in the mixture obtained in step 1-4.
• Equation (I) is derived as follows.
• The liquid-solid ratio (R) = the weight of the water in the mixture/the weight of non-water ingredients in the mixture, and can therefore be transformed as follows.
Step (1-3)
• In this step, the tobacco raw material is extracted using water in an amount that satisfies X above to obtain a tobacco extract liquid The conditions of the extraction are the same as those of the preliminary extraction.
Step (1-4)
• In this step, the tobacco extract liquid obtained in step (1-3) is mixed with other ingredient(s) to prepare a mixture that satisfies equation (I), specifically, that has the desired liquid-solid ratio R.
Solvent extraction
• Step (1) preferably comprises the following steps (1-1') through (1-4').
Step (1-1')
• In this step, the tobacco raw material is preliminarily extracted with a solvent mixture, and the extraction rate a' defined by the following equation (1') is determined. $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}\prime =\mathrm{Ed}\left(\mathrm{tobacco}\mathrm{extract}\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
• Ed (the tobacco extract E dry weight) is thus the weight of the tobacco extract liquid L' obtained via extraction minus the weight of the water and alcohol. Extraction can be effected as noted in the water extraction above.
Step (1-2')
• In this step, factor X relating to the weight of water in the solvent mixture used for further solvent mixture extraction is determined based on equation (I'). $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\prime \right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$
• X is defined as Ew (weight of water in tobacco extract liquid L')/Td (tobacco raw material dry weight). Specifically, X is the ratio of the weight of the water used in the solvent extraction relative to the dry weight of the tobacco raw material.
• Bw is the total weight of water in all ingredients B in the mixture obtained in step 1-4'. Bd is the total dry weight of all ingredients B in the mixture obtained in step 1-4'. The dry weight of the alcohol used in the solvent extraction is include in Bd.
• The symbol t is defined as the proportion of tobacco extract liquid used in solvent extraction: Ed/(Ed + Bd).
• Equation (1') is derived as follows in the same manner as in equation (I).
Step (1-3')
• In this step, the composition and amount of the solvent mixture used for the further extraction are first determined based on X. For example, when the weight ratio of water and alcohol in the solvent mixture used in the preliminary extraction is 1:z, then the solvent mixture is prepared by mixing the water (X) and alcohol (X×z). Extraction is then effected using the solvent mixture to obtain a tobacco extract liquid. The conditions of the extraction are the same as those of the preliminary extraction.
Step (1-4')
• This step can be carried out in the same manner as step (1-4).
(2) Step (2): Sheet preparation step
• In this step, a sheet is obtained from the mixture prepared in step (1). Sheets can be produced by known methods, but the effect noted above will be even more pronounced using the casting method. In casting methods, the tobacco extract liquid in the mixture must generally be concentrated in order to increase the concentration of solids in the mixture. A mixture having a suitable liquid-solid ratio is prepared in the present embodiment, however, thus allowing sheets to be cast without concentrating the extract liquid Concentration ordinarily entails heating and depressurization. Disadvantages that occur at such times are the loss or deterioration of some of the flavor components in the extract liquid. Depending on the flavor components, devices can become contaminated, or the deterioration of flavor components can lead to less smoking flavor. Any flavor components that are removed could also potentially be recovered, but that would be cumbersome. These drawbacks can be avoided in the present embodiment.
• When a sheet is obtained without concentrating the extract liquid, the mixture is, for example, cast onto a substrate, without going through a concentration step, to form a wet sheet. The wet sheet is then dried to obtain a tobacco sheet. It is particularly preferable to mix the tobacco extract liquid obtained in step (1-3) with the other ingredient(s) to prepare a mixture satisfying equation (I), and to obtain a sheet (cast sheet) from said mixture. The drying temperature is preferably 50 to 100°C. A tobacco sheet obtained by a casting method is also called a "cast sheet."
• The mixture used in a casting method can be prepared by a known method, but is preferably prepared by a method comprising the following steps:
• Step 1: a step for mixing a tobacco extract with an aerosol source such as glycerol (as well as mixing water, when water is to be added);
• Step 2: a step for mixing the binder into the mixture until the binder is mixed to homogeneity,
• Step 3: a step for mixing other solids into the mixture obtained in step 2.
When solids comprising the binder are mixed with each other first, the binder will "clump," a state which is difficult to resolve. In the present method, the binder and the aerosol source are mixed first, thus making it less likely that the binder will "clump." "Clumping" refers to a state in which ingredients are present in the form of clumps without being dispersed or dissolved. 2. Aerosol-generating sheet
• An aerosol-generating sheet obtained by the production method noted above is useful as filler for smoking articles. Examples of smoking articles include combusted smoking articles and heat-not-burn smoking articles. In particular, the aerosol-generating sheet obtained by the method noted above can be a tobacco-rich type and can be an aerosol source-rich type, as noted above, thus allowing a broad range of consumer needs to be addressed.
• Aspects of implementation are listed below.
• Aspect 1 A method for producing an aerosol-generating sheet containing a tobacco extract E and other ingredient(s) B, said method comprising:
  • (1) a step of preparing a mixture that contains the tobacco extract E and other ingredient(s) B, and that satisfies the following relationship: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{mixture}/\mathrm{weight}\mathrm{of}\mathrm{non}-\mathrm{water}\mathrm{ingredients}\mathrm{in}\mathrm{mixture}\ge 3$$
  • and (2) a step of obtaining a sheet from the mixture.
• Aspect 2 The production method according to aspect 1, wherein step (1) comprises:
  • (1-1) a step of preliminarily extracting the tobacco raw material with water to obtain a tobacco extract liquid L comprising the tobacco extract E and water, and determining an extraction rate a defined by the following equation (1): $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}=\mathrm{Ed}\left(\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
  • (1-2) a step of determining X relating to the weight of water used for further extraction by the same method as step (1-1), based on equation (I) below: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$
    • (here,
    • liquid-solid ratio ≥ 3 $$\mathrm{X}=\mathrm{Ew}\left(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{L}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
    • Bw: total weight of water in all ingredients B
    • Bd: total dry weight of all ingredients B $$\mathrm{t}=\mathrm{proportion}\mathrm{of}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{used}=\mathrm{Ed}/\left.\left(\mathrm{Ed}+\mathrm{Bd}\right)\right)$$
  • (1-3) a step of extracting the tobacco raw material using water in an amount that satisfies X above to obtain a tobacco extract liquid; and
  • (1-4) a step of mixing the tobacco extract liquid obtained in step (1-3) above with the other ingredient(s) to prepare a mixture that satisfies equation (I).
• Aspect 3 The production method according to aspect 1, wherein step (1) comprises:
  • (1-1) a step of preliminarily extracting the tobacco raw material with a solvent mixture comprising water and alcohol to obtain a tobacco extract liquid L' comprising the tobacco extract E, water, and alcohol, and determining an extraction rate a' defined by the following equation (1'): $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}\prime =\mathrm{Ed}\left(\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
  • (1-2) a step of determining X relating to the weight of water used for further extraction by the same method as step (1-1), based on equation (I') below: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\prime \right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$
    • (here, $$\mathrm{liquid}-\mathrm{solid}\mathrm{ratio}\ge 3$$ $$\mathrm{X}=\mathrm{Ew}\left(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{L}\prime \right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$
    • Bw: total weight of water in all ingredients B
    • Bd: total dry weight of all ingredients B $$\mathrm{t}=\mathrm{proportion}\mathrm{of}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{used}=\mathrm{Ed}/\left.\left(\mathrm{Ed}+\mathrm{Bd}\right)\right)$$
  • (1-3) a step of determining the amount of the solvent mixture used for the further extraction based on the weight ratio X, and extracting the tobacco raw material using that amount of solvent mixture to obtain a tobacco extract liquid; and (1-4) a step of mixing the tobacco extract liquid obtained in step (1-3) above with the other ingredient(s) to prepare a mixture that satisfies equation (I').
• Aspect 4 The production method according to any of aspects 1 through 3, wherein the content of the tobacco extract in the aerosol-generating sheet is 15 to 50% by weight based on dry weight.
• Aspect 5 The production method according to any of aspects 1 through 4, wherein the other ingredient(s) B comprise an aerosol source, and
  the content of the aerosol source in the aerosol-generating sheet is 10 to 60% by weight based on dry weight.
• Aspect 6 The production method according to any of aspects 1 through 5, wherein the other ingredient(s) comprise non-wood fiber, wood fiber, or a binder.
• Aspect 7 The production method according to aspect 6, wherein the non-wood fiber is dietary fiber.
• Aspect 8 The production method according to aspect 7, wherein the non-wood fiber is citrus fiber.
• Aspect 9 The production method according to any of aspects 6 through 8, wherein the binder is carboxyalkyl cellulose or guar gum.
• Aspect 10 The production method according to any of aspects 6 through 9, wherein the wood fiber content is lower than the non-wood fiber content.
EXAMPLES EXAMPLE 1 (1) Tobacco extract liquid
• Brazilian yellow leaf tobacco was prepared as the tobacco raw material. 250 g of the tobacco raw material and 1085 g of water were placed in a flask to effect extraction as the contents were stirred for about 60 minutes at 80°C.
(2) Mixture
• The following were used as other ingredients: wood pulp (softwood pulp); non-wood pulp (Herbacel AQ Plus CF-D/100, by DSP Gokyo Food & Chemical Co., Ltd.); aerosol source (glycerol); and binder (cellulose derivatives: CMCF30MC and CMC350HC, by Nippon Paper Industries Co., Ltd.; guar gum: GRINDSTED 175, by Dupont Danico). These were mixed with the tobacco extract to prepare a mixture. The mixing ratios are shown in Table 1.
(3) Sheet
• The mixture was cast onto a stainless steel sheet and dried in an oven at 80°C to prepare a 1.5 mm thick cast sheet. The dried sheet was conditioned at least overnight at 22°C and 60% RH, followed by visual assessment as to whether the sheet was capable of supporting liquids. The results are presented in Table 1.
• Sheets could be formed in all examples. However, the mixture (slurry) in Example 2 (liquid-solid ratio of 8) had a low viscosity, and was therefore in the acceptable range, but the workability was not good. A binder was then used to provide a slurry having a higher viscosity, resulting in good workability (Example 3). The use of 27% non-wood pulp (Herbacel) made it possible to produce a sheet having better workability despite a liquid-solid ratio of 7 (Example 4).

Claims (10)

1. A method for producing an aerosol-generating sheet containing a tobacco extract E and other ingredient(s) B, said method comprising:

   (1) a step of preparing a mixture that contains the tobacco extract E and other ingredient(s) B, and that satisfies the following relationship: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{mixture}/\mathrm{weight}\mathrm{of}\mathrm{non}-\mathrm{water}\mathrm{ingredients}\mathrm{in}\mathrm{mixture}\ge 3$$ and (2) a step of obtaining a sheet from the mixture.
2. The production method according to claim 1, wherein step (1) comprises:

   (1-1) a step of preliminarily extracting the tobacco raw material with water to obtain a tobacco extract liquid L comprising the tobacco extract E and water, and determining an extraction rate a defined by the following equation (1): $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}=\mathrm{Ed}\left(\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$

   (1-2) a step of determining X relating to the weight of water used for further extraction by the same method as step (1-1), based on equation (I) below: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$

   (here, $$\mathrm{liquid}-\mathrm{solid}\mathrm{ratio}\ge 3$$ $$\mathrm{X}=\mathrm{Ew}\left(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{L}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$

   Bw: total weight of water in all ingredients B

   Bd: total dry weight of all ingredients B $$\mathrm{t}=\mathrm{proportion}\mathrm{of}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{used}=\mathrm{Ed}/\left.\left(\mathrm{Ed}+\mathrm{Bd}\right)\right)$$

   (1-3) a step of extracting the tobacco raw material using water in an amount that satisfies X above to obtain a tobacco extract liquid; and

   (1-4) a step of mixing the tobacco extract liquid obtained in step (1-3) above with the other ingredient(s) to prepare a mixture that satisfies equation (I).
3. The production method according to claim 1, wherein step (1) comprises:

   (1-1) a step of preliminarily extracting the tobacco raw material with a solvent mixture comprising water and alcohol to obtain a tobacco extract liquid L' comprising the tobacco extract E, water, and alcohol, and determining an extraction rate a' defined by the following equation (1'): $$\mathrm{Extraction}\mathrm{rate}\mathrm{a}\prime =\mathrm{Ed}\left(\mathrm{E}\mathrm{dry}\mathrm{weight}\right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$

   (1-2) a step of determining X relating to the weight of water used for further extraction by the same method as step (1-1), based on equation (I') below: $$\mathrm{Liquid}-\mathrm{solid}\mathrm{ratio}=\left(\mathrm{X}/\mathrm{a}\prime \right)\times \mathrm{t}+\left(\mathrm{Bw}/\mathrm{Bd}\right)\times \left(1-\mathrm{t}\right)$$

   (here, $$\mathrm{liquid}-\mathrm{solid}\mathrm{ratio}\ge 3$$ $$\mathrm{X}=\mathrm{Ew}\left(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{in}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{L}\prime \right)/\mathrm{Td}\left(\mathrm{tobacco}\mathrm{raw}\mathrm{material}\mathrm{dry}\mathrm{weight}\right)$$

   Bw: total weight of water in all ingredients B

   Bd: total dry weight of all ingredients B $$\mathrm{t}=\mathrm{proportion}\mathrm{of}\mathrm{tobacco}\mathrm{extract}\mathrm{liquid}\mathrm{used}=\mathrm{Ed}/\left.\left(\mathrm{Ed}+\mathrm{Bd}\right)\right)$$

   (1-3) a step of determining the amount of the solvent mixture used for the further extraction based on the weight ratio X, and extracting the tobacco raw material using that amount of solvent mixture to obtain a tobacco extract liquid; and

   (1-4) a step of mixing the tobacco extract liquid obtained in step (1-3) above with the other ingredient(s) to prepare a mixture that satisfies equation (I').
4. The production method according to any of claims 1 through 3, wherein the content of the tobacco extract in the aerosol-generating sheet is 15 to 50% by weight based on dry weight.
5. The production method according to any of claims 1 through 4, wherein the other ingredient(s) B comprise an aerosol source, and
   the content of the aerosol source in the aerosol-generating sheet is 10 to 60% by weight based on dry weight.
6. The production method according to any of claims 1 through 5, wherein the other ingredient(s) B comprise non-wood fiber, wood fiber, or a binder.
7. The production method according to claim 6, wherein the non-wood fiber is dietary fiber.
8. The production method according to claim 7, wherein the non-wood fiber is citrus fiber.
9. The production method according to any of claims 6 through 8, wherein the binder is carboxyalkyl cellulose or guar gum.
10. The production method according to any of claims 6 through 9, wherein the wood fiber content is lower than the non-wood fiber content.