Classifications

• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
  • A24B15/00—Chemical features or treatment of tobacco; Tobacco substitutes, e.g. in liquid form
  • A24B15/10—Chemical features of tobacco products or tobacco substitutes
  • A24B15/16—Chemical features of tobacco products or tobacco substitutes of tobacco substitutes
  • A24B15/167—Chemical features of tobacco products or tobacco substitutes of tobacco substitutes in liquid or vaporisable form, e.g. liquid compositions for electronic cigarettes
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
  • A24B15/00—Chemical features or treatment of tobacco; Tobacco substitutes, e.g. in liquid form
  • A24B15/18—Treatment of tobacco products or tobacco substitutes
  • A24B15/28—Treatment of tobacco products or tobacco substitutes by chemical substances
  • A24B15/30—Treatment of tobacco products or tobacco substitutes by chemical substances by organic substances
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24F—SMOKERS' REQUISITES; MATCH BOXES; SIMULATED SMOKING DEVICES
  • A24F40/00—Electrically operated smoking devices; Component parts thereof; Manufacture thereof; Maintenance or testing thereof; Charging means specially adapted therefor
  • A24F40/10—Devices using liquid inhalable precursors
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24F—SMOKERS' REQUISITES; MATCH BOXES; SIMULATED SMOKING DEVICES
  • A24F42/00—Simulated smoking devices other than electrically operated; Component parts thereof; Manufacture or testing thereof
  • A24F42/10—Devices with chemical heating means

Definitions

• the present invention relates to a liquid composition for a liquid heating-type flavor inhaler and a preparation method therefor.
• the present invention also relates to a liquid heating-type flavor inhaler including the liquid composition for a liquid heating-type flavor inhaler.
• the present invention further relates to a method of reducing the gunpowder-like odor of benzoic acid in a liquid composition for a liquid heating-type flavor inhaler.
• a liquid heating-type flavor inhaler is a flavor inhaler that directly or indirectly heats, by an electric heat source or a chemical reaction-based heat source, a liquid composition for a liquid heating-type flavor inhaler to generate an aerosol and delivers the aerosol into the mouth through a mouthpiece member.
• a typical liquid composition for a liquid heating-type flavor inhaler (a liquid for electronic cigarettes (commonly called as e-liquid or e-juice)) comprises propylene glycol (PG), glycerol (GL), nicotine, and a flavor.
• Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2018-532377 describes a liquid formulation for e-vaping devices.
• the liquid formulation contains propylene glycol and substantially no amount of glycerol.
• Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2016-520061 describes a nicotine salt formulation for aerosol devices and methods therefor.
• the document specifies, for example, by the vapor pressure, melting point, or boiling point, an acid used to form a nicotine salt in the nicotine salt formulation.
• PTL 1 Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2018-532377
• PTL 2 Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2016-520061
• the present inventors found problems that a product containing benzoic acid in an e-liquid for lowering smoke flavor inhibition caused by nicotine (nicotine impact) emits a smell peculiar to benzoic acid during heating (gunpowder-like; herein, referred to as "gunpowder-like odor” or “benzoic acid odor” in some cases), and the resulting benzoic acid odor interferes with the emission of a flavor in the e-liquid, thereby destroying smoking flavor.
• benzoic acid has low solubility in PG and GL and hence requires a prolonged stirring step or heating step for the dissolution during production of e-liquids. For this reason, there are concerns about adverse effects on product quality, such as volatilization or deterioration of the components as well as effects on production efficiency.
• the present inventors also found that smoke flavor inhibition caused by nicotine (nicotine impact) is lowered even when other organic acids alone are used without using benzoic acid in a liquid composition containing nicotine for a heating-type flavor inhaler, thereby arriving at the present invention concerning a liquid composition containing no benzoic acid.
• the present invention encompasses, but not limited to, the following embodiments.
• a liquid composition (I) for a liquid heating-type flavor inhaler of the present invention has excellent features of reduced smoke flavor inhibition caused by nicotine due to a mixture of benzoic acid and other organic acids as well as reduced gunpowder-like odor of benzoic acid to be generated during heating.
• a method of preparing the above-mentioned liquid composition includes dissolving benzoic acid first in propylene glycol in the presence of nicotine and then mixing with glycerol. This makes it possible to efficiently prepare, in a short time without heating treatment, a liquid composition for a liquid heating-type flavor inhaler containing benzoic acid, which is difficult to dissolve in glycerol.
• a liquid composition (II) for a liquid heating-type flavor inhaler of the present invention effectively reduces smoke flavor inhibition caused by nicotine solely by organic acids excluding benzoic acid without using benzoic acid. Since the liquid composition does not use benzoic acid, a preparation method therefor does not require a step of dissolving benzoic acid first in propylene glycol in the presence of nicotine. Nicotine may appropriately be mixed into, for example, after dissolving organic acids to be used in propylene glycol or glycerol.
• the present invention encompasses, in a non-limiting manner, the following embodiments.
• the present invention relates to a liquid composition for a liquid heating-type flavor inhaler.
• a liquid composition for a liquid heating-type flavor inhaler contains
• a non-combustion flavor inhaler is a flavor inhaler that enables inhalation of a flavor without involving combustion.
• Such non-combustion flavor inhalers include: heating-type flavor inhalers equipped with an electric heat source or a chemical reaction-based heat source; and non-heating flavor inhalers without heat source.
• a "liquid heating-type flavor inhaler,” as a form of non-combustion flavor inhalers, is a flavor inhaler that has a cartridge for holding a liquid composition (aerosol source) containing nicotine, heats directly or indirectly the aerosol source (liquid) by an electric heat source or a chemical reaction-based heat source to generate an aerosol containing nicotine and a flavor, and delivers the aerosol into the mouth through a mouthpiece member.
• a liquid composition aerosol source
• a porous or fibrous body impregnated with an aerosol source of a liquid, such as glycerol or propylene glycol, or a mixed solution thereof is electrically heated to generate a gas of mixed vapor and particulate substance, and the gas is then mixed into air drawn through the flavor inhaler.
• a consumer generally inhales the resulting mixed gas by drawing at the end of the flavor inhaler (mouth side end, filter end, or mouthpiece end).
• a liquid composition for a liquid heating-type flavor inhaler (2) nicotine, (3) benzoic acid, and (4) one or more organic acids excluding benzoic acid are dissolved in solvents of propylene glycol and glycerol.
• a liquid composition for a liquid heating-type flavor inhaler is referred to as "e-liquid” in some cases.
• benzoic acid reduces smoke flavor inhibition caused by nicotine, and other organic acids reduce the gunpowder-like odor of benzoic acid.
• a mole ratio of (2) nicotine to the total of (3) benzoic acid and (4) one or more organic acids excluding benzoic acid falls within a range of 3:0.1 to 0.1:3, 2:0.5 to 0.5:2, or 1:0.85 to 1:1.15.
• a mole ratio of (2) nicotine to the total of (3) benzoic acid and (4) one or more organic acids excluding benzoic acid falls within a range of 1:0.85 to 1:1.15.
• a liquid composition for a liquid heating-type flavor inhaler contains (4) one or more organic acids excluding benzoic acid.
• organic acids are a collective term for acids of organic compounds. The majority of organic acids are carboxylic acids having a carboxyl group or sulfonic acids having a sulfo group.
• the types of (4) organic acids excluding benzoic acid to be used for a liquid composition of the present invention are not particularly limited.
• the number of (4) organic acids excluding benzoic acid is also not particularly limited, and two or more (4) organic acids excluding benzoic acid may be contained.
• (4) organic acids excluding benzoic acid include lactic acid.
• the liquid composition for a liquid heating-type flavor inhaler may contain, in addition to lactic acid, any one selected from tartaric acid, fumaric acid, levulinic acid, malonic acid, acetic acid, adipic acid, citric acid, malic acid, pyruvic acid, sorbic acid, and mixtures thereof as (4) one or more organic acids excluding benzoic acid.
• the liquid composition may contain, in addition to lactic acid, any one selected from tartaric acid, fumaric acid, levulinic acid, malonic acid, and mixtures thereof as (4) one or more organic acids excluding benzoic acid.
• the liquid composition may contain, in addition to lactic acid, tartaric acid as (4) one or more organic acids excluding benzoic acid.
• Organic acids contained in a liquid composition for a liquid heating-type flavor inhaler are preferably organic acids, for which safety to organisms has been recognized, such as those approved as food additives.
• a mole ratio of lactic acid to organic acids excluding lactic acid is not particularly limited.
• a mole ratio of lactic acid to organic acids excluding lactic acid is 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1.
• a mole ratio of lactic acid to organic acids excluding lactic acid is about 3:1.
• organic acids excluding benzoic acid are preferably organic acids soluble in glycerol and/or propylene glycol.
• organic acids excluding benzoic acid have solubility in glycerol of 0.32 mol/kg or more in molality.
• Lactic acid has properties of relatively satisfactory solubility in glycerol and propylene glycol compared with benzoic acid and other organic acids.
• organic acids for example, there exist those having a higher dissolution rate in propylene glycol than in glycerol, such as tartaric acid and malic acid (Example 8).
• a mole ratio of (2) nicotine to (3) benzoic acid falls within a range of 1:0.9 to 1:0.1 or 1:0.7 to 1:0.15. In a preferable embodiment of the liquid composition for a liquid heating-type flavor inhaler, a mole ratio of (3) benzoic acid to (2) nicotine is 60% or less.
• a mole ratio of (2) nicotine to (4) organic acids excluding benzoic acid falls within a range of 2:1 to 1:0.1 or 1:0.9 to 1:0.3. In an embodiment of the liquid composition for a liquid heating-type flavor inhaler, a mole ratio of (2) nicotine to (4) organic acids excluding benzoic acid falls within a range of 1:0.9 to 1:0.3.
• a ratio of propylene glycol to glycerol is 1:1 to 1:3, more preferably 1:1 to 1:2.5, and further preferably 1:about 2.4.
• the liquid composition for a liquid heating-type flavor inhaler has a water content of 10 weight% or less, 5 weight% or less, 3 weight% or less, or 1.5 weight% or less. In an embodiment, the liquid composition for a liquid heating-type flavor inhaler contains substantially no water.
• the expression of"...contains substantially no water” means that "water” is not added in the steps of preparing the liquid composition.
• the liquid composition for a liquid heating-type flavor inhaler may further contain, in addition to components (1) to (4), other components for an aerosol source of the liquid heating-type flavor inhaler.
• the liquid composition contains a flavor.
• the present invention relates to a method of preparing a liquid composition for a liquid heating-type flavor inhaler.
• a method of preparing a liquid composition for a liquid heating-type flavor inhaler includes steps of:
• Benzoic acid has properties of being less soluble in glycerol. Meanwhile, lactic acid has properties of relatively satisfactory solubility in glycerol and propylene glycol compared with benzoic acid and other organic acids.
• organic acids for example, there exist those having a higher dissolution rate in propylene glycol than in glycerol, such as tartaric acid and malic acid.
• the preparation method of the present invention includes: first dissolving nicotine and benzoic acid in propylene glycol (solution (A)) (step (i)); separately dissolving lactic acid in glycerol (solution (B)) (step (ii)); further dissolving, as necessary, one or more organic acids excluding benzoic acid and lactic acid in propylene glycol or glycerol (solution (C)) (step (iii)); and after dissolving the respective organic acids, mixing solution (A), solution (B), and solution (C).
• This procedure makes it possible to prepare efficiently in a short time even a liquid composition for a liquid heating-type flavor inhaler containing benzoic acid, which is less soluble in glycerol.
• a method of preparing a liquid composition for a liquid heating-type flavor inhaler includes steps of:
• the method of preparing a liquid composition for a liquid heating-type flavor inhaler further includes adding a flavor in a step after step (i).
• a flavor after preparing solution (A) by dissolving nicotine and benzoic acid in propylene glycol in step (i), it is possible to shorten stirring time after the addition of a flavor, thereby preventing or reducing the loss of flavor components.
• the addition of components, such as a flavor may be performed before, simultaneously with, or after step (iv) of mixing solution (A), solution (B), and solution (C) or step (v) of dissolving glycerol, lactic acid, and so forth in solution (A) provided that the addition is performed after step (i).
• the present invention relates to a liquid heating-type flavor inhaler.
• the liquid heating-type flavor inhaler includes a liquid composition for a liquid heating-type flavor inhaler of the present invention.
• the present invention relates to a method of reducing a gunpowder-like odor of benzoic acid in a liquid composition for a liquid heating-type flavor inhaler.
• the method may include incorporating lactic acid as (4) one or more organic acids excluding benzoic acid.
• the order of incorporating (1) propylene glycol and glycerol, (2) nicotine, (3) benzoic acid, and (4) one or more organic acids excluding benzoic acid into the liquid composition for a heating-type flavor inhaler is not particularly limited.
• a liquid composition for a liquid heating-type flavor inhaler may be prepared in accordance with the method described in "2. Method of Preparing Liquid Composition for Liquid Heating-type Flavor Inhaler.”
• a method of preparing a liquid composition for a liquid heating-type flavor inhaler includes steps of:
• a method of preparing a liquid composition for a liquid heating-type flavor inhaler includes steps of:
• reducing a gunpowder-like odor of benzoic acid means that a weaker gunpowder-like odor of benzoic acid is sensed compared with a case in which (4) organic acids excluding benzoic acid are not contained.
• the present invention relates to a liquid composition for a liquid heating-type flavor inhaler.
• a liquid composition for a liquid heating-type flavor inhaler contains
• a liquid composition (II) for a liquid heating-type flavor inhaler is an embodiment (solely) containing, as organic acids, organic acids excluding benzoic acid without containing benzoic acid.
• liquid composition for a liquid heating-type flavor inhaler (2) nicotine and (4) one or more organic acids excluding benzoic acid are dissolved in solvents of propylene glycol and glycerol.
• a mole ratio of (2) nicotine to (4) one or more organic acids excluding benzoic acid falls within a range of 3:0.1 to 0.1:3, 2:0.5 to 0.5:2, or 1:0.85 to 1:1.15. In a preferable embodiment, a mole ratio of (2) nicotine to (4) one or more organic acids excluding benzoic acid falls within a range of 1:0.85 to 1:1.15.
• the liquid composition for a liquid heating-type flavor inhaler contains (4) one or more organic acids excluding benzoic acid.
• organic acids are a collective term for acids of organic compounds. The majority of organic acids are carboxylic acids having a carboxyl group or sulfonic acids having a sulfo group.
• the types of (4) organic acids excluding benzoic acid to be used for the liquid composition of the present invention are not particularly limited.
• the number of (4) organic acids excluding benzoic acid is also not particularly limited, and two or more (4) organic acids excluding benzoic acid may be contained.
• (4) organic acids excluding benzoic acid include lactic acid.
• any one selected from tartaric acid, fumaric acid, levulinic acid, malonic acid, acetic acid, adipic acid, citric acid, malic acid, pyruvic acid, sorbic acid, and mixtures thereof may be contained in addition to lactic acid as (4) organic acids excluding benzoic acid.
• organic acids excluding benzoic acid have solubility in glycerol of 0.32 mol/kg or more in molality.
• a ratio of propylene glycol to glycerol is 1:1 to 1:3, more preferably 1:1 to 1:2.5, and further preferably 1:about 2.4.
• the liquid composition for a liquid heating-type flavor inhaler has a water content of 10 weight% or less, 5 weight% or less, 3 weight% or less, or 1.5 weight% or less. In an embodiment, the liquid composition for a liquid heating-type flavor inhaler contains substantially no water.
• the expression of"...contains substantially no water” means that "water” is not added in the steps of preparing the liquid composition.
• the liquid composition for a liquid heating-type flavor inhaler may further contain, in addition to components (1), (2) and (4), other components for an aerosol source of the liquid heating-type flavor inhaler.
• the liquid composition contains a flavor.
• the present invention relates to a method of preparing a liquid composition for a liquid heating-type flavor inhaler.
• a method of preparing a liquid composition for a liquid heating-type flavor inhaler includes steps of:
• Lactic acid has properties of relatively satisfactory solubility in glycerol and propylene glycol compared with benzoic acid and other organic acids.
• organic acids for example, there exist those having a higher dissolution rate in propylene glycol than in glycerol, such as tartaric acid and malic acid.
• the preparation method of the present invention includes: first dissolving lactic acid in glycerol (solution (B)) (step (i'); further dissolving, as necessary, one or more organic acids excluding benzoic acid and lactic acid in propylene glycol or glycerol (solution (C)) (step (ii')); and after dissolving the respective organic acids, mixing nicotine, solution (B), and solution (C).
• benzoic acid is not used for a liquid composition (II) for a liquid heating-type flavor inhaler, the preparation method does not require a step of dissolving benzoic acid first in propylene glycol in the presence of nicotine.
• Nicotine may appropriately be mixed into, for example, after dissolving organic acids to be used in propylene glycol or glycerol.
• the method of preparing a liquid composition for a liquid heating-type flavor inhaler further includes adding a flavor.
• the preparation method (II) does not include a relatively time-consuming step of dissolving benzoic acid in propylene glycol. Accordingly, the timing of adding a flavor is not particularly limited and may be before, simultaneously with, or after step (i'), step (ii') or step (iii').
• the present invention relates to a liquid heating-type flavor inhaler.
• the liquid heating-type flavor inhaler includes a liquid composition for a liquid heating-type flavor inhaler of the present invention.
• liquid composition for a liquid heating-type flavor inhaler as well as a liquid heating-type flavor inhaler are as described in "1.
• Liquid Composition (I) for Liquid Heating-type Flavor Inhaler or "5.
• Liquid Composition (II) for Liquid Heating-type Flavor Inhaler are as described in "1.
• Liquid Composition (I) for Liquid Heating-type Flavor Inhaler or "5.
• Liquid Composition (II) for Liquid Heating-type Flavor Inhaler for Liquid Heating-type Flavor Inhaler.
• citric acid As acids satisfying these conditions, it was decided to employ two acids of acetic acid (AA) and citric acid (CA) for investigation.
• AA acetic acid
• CA citric acid
• Each e -liquid (a liquid composition for a liquid heating-type flavor inhaler) having the composition shown in Table 1 was prepared, and a capsule for a liquid heating-type flavor inhaler that heats a liquid at 200°C to 300°C was filled with 1.5 mL of the e-liquid.
• Sensory evaluation was conducted by a panel of seven experts (a panel that is routinely engaged in flavor development and has high ability in sensory evaluation) using a device for a liquid heating-type flavor inhaler that heats a liquid at 200°C to 300°C.
• Table 2 shows comments obtained in the sensory evaluation.
• Lot 1-1 in which the amount of benzoic acid is merely simply reduced, exhibits evidently weak effects of lowering smoke flavor inhibition caused by nicotine without satisfying the prerequisite for the development and hence is unsuitable.
• acetic acid has the following advantages when the physical/chemical characteristics are compared with other organic acids, such as citric acid.
• acetic acid was selected as the most promising candidate for an organic acid that replaces benzoic acid and used for the subsequent investigation.
• Each e -liquid having the composition shown in Table 3 was prepared, and a capsule for a liquid heating-type flavor inhaler that heats a liquid at 200°C to 300°C was filled with 1.5 mL of the e-liquid. Sensory evaluation was conducted by a panel of 14 experts using a device for a liquid heating-type flavor inhaler that heats a liquid at 200°C to 300°C.
• a comparative example an e-liquid solely containing, as an acid, benzoic acid in mole equal to nicotine was used.
• each evaluation item in Table 4 the intensity of each sensory evaluation item was determined as “strong,” “same,” or “weak” for each lot relative to the Comparative Example.
• a statistical significance level ⁇ was set to commonly employed 0.05 (significance level of 5%). When a value p calculated as a frequency of the distribution result of the panel is 0.05 or less, it is determined that the value exceeds the statistical significance level, in other words, is significant.
• Tables 5, 7, 9, 11, and 13 show results on whether the vote distribution for each lot is significantly deviated from the expected value.
• the numerical values for "strong,” “same,” and “weak” in the respective evaluation items of “benzoic acid odor,” “acetic acid odor,” and “acidic taste” represent the number of experts who chose each rating (14 experts in total).
• the probability (p) indicates the probability of such deviation for each evaluation item of "benzoic acid odor," “acetic acid odor,” and “acidic taste.” As the degree of deviation increases, the probability (p) decreases.
• the probability (p) of 0.05 or less means that the distribution of the panel experts is particularly concentrated on the corresponding item, in other words, the deviation is significant.
• Tables 6, 8, 10, 12, and 14 show the probability obtained by the ⁇ 2 test, which indicates whether the number of votes is significantly concentrated among “strong,” “same,” and “weak” relative to the expected value.
• Each numerical value in these tables indicates the probability of the number of experts who would choose “strong,” “same,” and “weak” in each evaluation of "benzoic acid odor,” “acetic acid odor,” and “acidic taste.”
• the numerical value of "0.001" in "strong” for "acetic acid odor” in Table 6 represents the probability in the ⁇ 2 test for the fact that 11 experts, among 14 experts of the panel, chose “strong” (from Table 5).
• the probability of 0.05 or less means that the distribution of the panel experts is particularly concentrated on the corresponding item, in other words, the choice is significant. Accordingly, the numerical value of "0.001" in “strong” for "acetic acid odor” in Table 6 is 0.05 or less and thus means that the choice made by 11 experts, among 14 experts of the panel, is significant.
• benzoic acid odor is considered as "weak" relative to the Comparative Example at a significance level of 5% for Lot 2-3, 2-4, and 2-5, in other words, in a mole ratio of acetic acid to benzoic acid within the range of 3:7 to 5:5 (i.e. 1:1). Consequently, it was confirmed that benzoic acid odor is effectively reduced through partial replacement of benzoic acid by acetic acid. Moreover, it is concluded that such effects are exhibited when 30% or more of benzoic acid in mole equal to nicotine is replaced by acetic acid.
• Example 2 it was confirmed that benzoic acid odor is effectively reduced through partial replacement of benzoic acid by acetic acid.
• excessively strong acetic acid odor or acidic taste could interfere with the emission of a flavor in an e-liquid containing the flavor.
• acetic acid odor or acidic taste per se would be perceived as off-note or off-taste to damage acceptance of/preference for an e-liquid itself.
• This Example investigated the reduction of acetic acid odor and acidic taste as much as possible while retaining the function in reducing gunpowder odor of benzoic acid.
• each e-liquid having the composition containing citric acid in addition to acetic acid and benzoic acid was prepared to confirm the effects through sensory evaluation.
• e-liquids of this Example were added with a flavor to reproduce the state close to an embodiment that is actually used for a liquid heating-type flavor inhaler.
• a tobacco-type flavor that is empirically considered less likely to exhibit such effects was used. Accordingly, sensory evaluation concerning acetic acid odor, benzoic acid odor, and acidic taste in this Example was not affected by the flavor.
• Each e-liquid having the composition shown in Table 15 was prepared. On this occasion, citric acid monohydrate (CA ⁇ H 2 O) was dissolved in GL in advance to form solution C. Moreover, the flavor was added at the end after mixing solution A and solution B.
• citric acid monohydrate CA ⁇ H 2 O
• Example 2 The preparation of evaluation samples and the sensory evaluation method are the same as in "2-2 Experimental Procedure" of Example 2, and sensory evaluation was conducted by the panel of 16 experts.
• a comparative example used was an e-liquid having the same organic acid composition as Lot 2-3, for which the effects of reducing benzoic acid odor had been confirmed in Example 2, in other words, having a mole ratio of acetic acid to benzoic acid of 3:7.
• Analysis results A are shown in Tables 16, 18, 20, 22, and 24, and analysis results B are shown in Tables 17, 19, 21, 23, and 25.
• Benzoic acid is a relatively hydrophobic substance with low solubility in water.
• Main solvents of an e-liquid are PG and GL.
• solubility of benzoic acid in these solvents is not so high. Consequently, prolonged stirring or heating is often required for dissolving benzoic acid alone in these solvents.
• the present inventors focused on the facts that benzoic acid neutralized with nicotine or in the state of nicotine benzoic acid salt exhibits enhanced hydrophilicity and that PG would be a more suitable solvent for dissolving a hydrophobic substance than GL in comparison of structures between PG having two hydrophilic hydroxy groups and GL having three such groups.
• the inventors made hypothesis based on the above consideration that two conditions for efficiently dissolving benzoic acid are (a) dissolving benzoic acid in a solvent in the presence of nicotine and (b) dissolving in PG alone, followed by investigation of mixing procedures in methods of preparing e-liquids.
• E-liquids of the composition shown in Table 26 were prepared through two mixing procedures of I and II below to compare the time required for completely dissolving benzoic acid.
• Each weighed raw material was fed into a beaker and stirred at 1000 rpm using a stir bar within the beaker and a magnetic stirrer. After the end of stirring, the presence or absence of dissolution residue was observed through visual inspection.
• organic acids third organic acids excluding benzoic acid and acetic acid (citric acid in Example 3)
• organic acids fed to PG (solution A) together with nicotine and benzoic acid compete for the neutralization reaction between benzoic acid and nicotine and thus impede dissolution of benzoic acid.
• organic acids excluding benzoic acid and acetic acid are presumably suitable for dissolving in GL solvent in advance separately from solution A.
• the organic acids may be fed into the system (solution A) directly without dissolving in GL in advance.
• citric acid was used in Example 3 as an organic acid (third organic acid) excluding benzoic acid and acetic acid
• any acid may be used in place of citric acid provided that a required amount of the acid can be dissolved in GL completely.
• Conditions for a possible embodiment of a case in which a third organic acid reaches the highest concentration when dissolved in GL in advance within the scope of the present invention are as follows.
• long-chain fatty acids such as stearic acid and palmitic acid, exhibit evidently high hydrophobicity and hence are considered unsuitable due to low solubility in PG and GL.
• organic acids having a short carbon chain or a plurality of polar functional groups are expected to have satisfactory solubility in PG and GL and thus can be candidate substances.
• Such examples include adipic acid, citric acid, fumaric acid, lactic acid, malic acid, malonic acid, pyruvic acid, sorbic acid, succinic acid, and tartaric acid.
• This Example investigated whether these organic acids as candidates for third organic acids can be used under the above-described conditions.
• solubility tests in GL were conducted.
• GL and each acid in the amounts shown in Table 28 were weighed into a beaker and stirred using a stir bar within the beaker and a magnetic stirrer at 500 rpm and room temperature for 12 hours. After the end of stirring, the presence or absence of dissolution residue was observed through visual inspection, and a solution with observed solid residue was determined as undissolved.
• This Example investigated the effects of lowering smoke flavor inhibition caused by nicotine (nicotine impact) by each organic acid alone.
• Each e-liquid (a liquid composition for a liquid heating-type flavor inhaler) having the composition shown in Table 29 was prepared, and a capsule for a liquid heating-type flavor inhaler that heats a liquid at 200°C to 300°C was filled with 1.5 mL of the e-liquid.
• Sensory evaluation was conducted by a panel of eight experts (a panel that is routinely engaged in flavor development and has high ability in sensory evaluation) using a device for a liquid heating-type flavor inhaler that heats a liquid at 200°C to 300°C.
• lactic acid As shown in Table 29, concerning the effects of lowering smoke flavor inhibition caused by nicotine (nicotine impact), a plurality of organic acids were found to exhibit such lowering effects comparable to benzoic acid. Among the organic acids tested in this Example, lactic acid attained particularly strong effects. Lactic acid, which is liquid and exhibits satisfactory solubility in PG and GL, has a great advantage of easy handling in production. Meanwhile, slightly negative sensory elements (slight acidic odor, slight oiliness) were perceived for lactic acid. Accordingly, it is considered further desirable to combine lactic acid with other organic acids.
• the present Example investigated the composition for liquid compositions containing benzoic acid, lactic acid, and other organic acids.
• a ratio of benzoic acid to nicotine was set to 0.6 or less.
• Tartaric acid, fumaric acid, levulinic acid, and malonic acid which lack strong negative elements and exhibit strong effects of lowering nicotine impact in Example 6, were investigated as candidates for combining with lactic acid.
• a ratio of lactic acid to organic acids excluding benzoic acid and lactic acid was set to 3:1.
• an e-liquid of the composition containing benzoic acid alone but neither lactic acid nor other organic acids was used.
• Table 31 shows the composition of each sample e-liquid subjected to sensory evaluation and the results of the sensory evaluation (by a panel of 14 experts).
• the p value for the number of votes for "strong” or “weak” indicates a statistical probability of the number of times in which "strong” was chosen to occur relative to the total number n.
• gunpowder odor benzoic acid odor
• the p value is 0.006, in other words, 0.6%. This means that when “strong” and “weak” are randomly chosen 14 times at a probability of 50% each, the statistical probability of a pattern in which "weak” is coincidentally chosen 11 times is 0.6%. This value of 0.6% is smaller than a typical significance level of 1%, and hence it is concluded that the deviation in which "weak” was chosen 11 times out of 14 times is meaningful deviation at a significance level of 1%.

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