JP7736408B2 - Liquid skin cleanser composition - Google Patents

Description

The present invention relates to a skin cleansing composition.

Skin cleanser compositions used for washing hands are required to have excellent foam quality, post-cleaning feel, non-irritation to the skin, and stability, as well as high bactericidal activity. For this reason, synthetic chemicals have traditionally been used as bactericidal ingredients (see, for example, Patent Documents 1 and 2). However, the formulation conditions and amounts of these synthetic chemicals are generally determined based on safety and skin irritation considerations. Furthermore, because they also kill resident bacteria that enhance the skin's barrier function, repeated washing with skin cleanser compositions with high bactericidal activity can lead to rough, dry hands.

Therefore, there is a demand for plant-derived antibacterial ingredients that are gentle on the skin. However, extracts obtained by common plant extraction methods, such as extraction with organic solvents such as alcohol, and extraction by acid or alkali treatment, suffer from decomposition or aggregation of the active ingredients, resulting in coloration and a distinctive unpleasant taste and odor, which limits the conditions for incorporation into cosmetics such as skin cleanser compositions. Furthermore, these plant extracts have low bactericidal activity, and even when incorporated into skin cleanser compositions, they do not have the same bactericidal activity as synthetic chemicals.

Therefore, there is a strong demand for a skin cleanser composition that has high bactericidal activity against pathogenic bacteria such as E. coli while preserving the normal flora that enhances the skin's barrier function, is colorless, has a good liquid appearance, is free of unpleasant taste and odor, has excellent foam quality, post-cleansing feel, is non-irritating to the skin, and is stable.

International Publication No. 2011/043226 Japanese Patent Application Laid-Open No. 2006-182698

The present invention aims to solve the above-mentioned problems of the past and achieve the following objectives. Specifically, the present invention aims to provide a skin cleanser composition that has high bactericidal activity against pathogenic bacteria such as E. coli while preserving the normal flora that enhances the skin's barrier function, is colorless, has a good liquid appearance, is free of unpleasant taste and odor, and has excellent foam quality, post-cleansing feel, is non-irritating to the skin, and is stable.

As a result of extensive research to achieve the above-mentioned objective, the inventors have discovered that a skin cleanser composition containing (A) an anionic surfactant, (B) at least one plant extract selected from a Sasa kurilensis extract and an aqueous extract of peppermint, and (C) at least one polyhydric alcohol selected from glycerin, 1,3-butylene glycol, and propylene glycol, and having a mass ratio [(C)/(B)] of the content of the component (C) to the content of the component (B) of 3 to 30, exhibits high bactericidal activity against pathogenic bacteria such as Escherichia coli while preserving the resident bacteria that enhance the skin's barrier function, is colorless, has a good liquid appearance, is free from any unpleasant taste or odor, and has excellent foam quality, post-cleansing feel, is non-irritating to the skin, and is stable.

The present invention is based on the above findings by the present inventors, and the means for solving the above problems are as follows:
<1> (A) an anionic surfactant,
(B) at least one plant extract selected from a Sasa kurilensis extract and a water extract of mint;
(C) at least one polyhydric alcohol selected from glycerin, 1,3-butylene glycol, and propylene glycol;
and the mass ratio of the content of the component (C) to the content of the component (B) [(C)/(B)] is 3 to 30.
<2> The skin cleanser composition according to <1>, wherein the Sasa kurilensis extract of component (B) is Sasa kurilensis water, and the mint water extract of component (B) is mint oil.
<3> The content of the component (A) is 5% by mass to 12% by mass,
The content of the Sasa kurilensis extract of the component (B) is 0.5% by mass to 1.2% by mass, and the content of the mint water extract of the component (B) is 0.2% by mass to 0.5% by mass,
The skin cleanser composition according to any one of <1> and <2>, wherein the component (C) is 5% by mass to 10% by mass.
<4> The skin cleanser composition according to any one of <1> to <3>, further comprising (D) an amphoteric surfactant.
<5> The skin cleanser composition according to <4>, wherein the content of the component (D) is 0.5% by mass to 4% by mass.

The present invention solves the above-mentioned problems of the past and achieves the above-mentioned objectives, providing a skin cleanser composition that has high bactericidal activity against pathogenic bacteria such as E. coli while preserving the normal flora that enhances the skin's barrier function, is colorless, has a good liquid appearance, is free from unpleasant taste and odor, and has excellent foam quality, post-cleansing feel, is non-irritating to the skin, and is stable.

(Skin cleanser composition)
The skin cleanser composition of the present invention contains (A) an anionic surfactant, (B) at least one plant extract selected from a Sasa kurilensis extract and an aqueous extract of peppermint, and (C) at least one polyhydric alcohol selected from glycerin, 1,3-butylene glycol, and propylene glycol, and preferably further contains (D) an amphoteric surfactant, and may further contain other components as necessary.

<(A) Anionic Surfactant>
The anionic surfactant as component (A) is contained mainly to improve foam quality, feel after washing, and bactericidal activity against Escherichia coli.

The anionic surfactant of component (A) is not particularly limited and can be selected appropriately depending on the purpose. Examples include higher fatty acid salts, polyoxyethylene (POE) alkyl ether sulfates, ether carboxylates, and amino acid surfactants. These may be used alone or in combination of two or more. Among these, higher fatty acid salts are preferred in terms of foam quality, feel after rinsing, and bactericidal activity against E. coli.

- Higher fatty acid salts -
The higher fatty acid salt in component (A) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include laurate, myristate, palmitate, stearate, etc. These may be used alone or in combination of two or more. Among these, higher fatty acid salts containing both laurate and myristate are preferred.

The counter ion of the higher fatty acid salt is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include alkali metal salts, amine salts, and amino acid salts.
The alkali metal salt is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include sodium salts and potassium salts.
The amine salt is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ammonium salts; monoethanolamine salts, diethanolamine salts, triethanolamine salts, and alkanolamine salts such as 2-amino-2-methylpropanol and 2-amino-2-methylpropanediol.
The amino acid salt is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include lysine salt and arginine salt.
Among these, alkali metal salts are preferred, and potassium salts are particularly preferred, in that they provide excellent foam elasticity.

The higher fatty acid salt may be suitably synthesized or may be a commercially available product.
Examples of commercially available higher fatty acid salts include, by trade name, NIKKOL potassium laurate LK-120 (potassium laurate), NIKKOL potassium myristate MK-140 (potassium myristate), and TYSOAP MNK-40 (liquid blend of potassium coconut oil fatty acid and potassium myristate (all manufactured by Nikko Chemicals Co., Ltd.)).

The higher fatty acid salt can be blended as a higher fatty acid salt, or the higher fatty acid and a salt that serves as the counter ion, such as potassium hydroxide, can be added separately to a blending tank and neutralized to form the higher fatty acid salt.

The higher fatty acid used for preparing the higher fatty acid salt may be an appropriately synthesized product or a commercially available product.
Examples of commercially available higher fatty acids include, by trade name, NAA (registered trademark)-122 (lauric acid), NAA (registered trademark)-142 (myristic acid), NAA (registered trademark)-160 (palmitic acid), and NAA (registered trademark)-180 (stearic acid) (all manufactured by NOF Corporation), Kortacid 1299 (lauric acid), and Kortacid 1499 (myristic acid) (all manufactured by Pacific Oleochemicals).

The content of the laurate salt is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 2% to 12% by mass, and more preferably 4% to 10% by mass, based on the total amount of the skin cleanser composition.

The content of the myristate salt is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.5% to 10% by mass, and more preferably 1% to 8% by mass, of the total amount of the skin cleanser composition.

The content of the palmitate is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1% to 11% by mass, and more preferably 3% to 9% by mass, based on the total amount of the skin cleanser composition.

The content of the stearate salt is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.1% to 3% by mass, and more preferably 0.2% to 1% by mass, based on the total amount of the skin cleanser composition.

-Polyoxyethylene alkyl ether sulfate-
The polyoxyethylene alkyl ether sulfate in the component (A) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include compounds represented by the following general formula (A1): The polyoxyethylene alkyl ether sulfate may be used alone or in combination of two or more types.

In the general formula (A1), R ¹ represents an alkyl group, and the alkyl group moiety preferably has 10 to 14 carbon atoms.

In the general formula (A1), n represents the average number of moles of ethylene oxide (E.O.) added, and the average number of moles of ethylene oxide added is preferably 1 to 5.

In the general formula (A1), X represents an alkali metal or ammonium.
The alkali metal is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include sodium and potassium.

Specific examples of the polyoxyethylene alkyl ether sulfates include polyoxyethylene (1) lauryl ether sodium sulfate, polyoxyethylene (2) lauryl ether sodium sulfate (also known as POE (2) sodium laureth sulfate), polyoxyethylene (3) lauryl ether sodium sulfate (also known as POE (3) sodium laureth sulfate), polyoxyethylene (4) lauryl ether sodium sulfate, polyoxyethylene (5) lauryl ether sodium sulfate, polyoxyethylene (3) alkyl (C12,13) ether sodium sulfate, polyoxyethylene (2) lauryl ether ammonium sulfate, and polyoxyethylene (3) lauryl ether ammonium sulfate.
The numbers in the parentheses indicate the average number of moles (n) of ethylene oxide (E.O.) added.

The polyoxyethylene alkyl ether sulfate may be suitably synthesized or may be a commercially available product.
Commercially available polyoxyethylene alkyl ether sulfates include, for example, EMALE 20C (polyoxyethylene (3) lauryl ether sodium sulfate), EMALE 270J (polyoxyethylene (2) lauryl ether sodium sulfate), EMALE 20CM (polyoxyethylene (3) alkyl (C12,13) ether sodium sulfate), EMALE 125HP (polyoxyethylene (1) lauryl ether sodium sulfate) (all manufactured by Kao Corporation), ALSCOP (registered trademark) DA-330S (polyoxyethylene (3) alkyl (C 12,13) sodium lauryl ether sulfate), Arscope (registered trademark) A-225B (ammonium polyoxyethylene (2) lauryl ether sulfate) (all manufactured by Toho Chemical Industry Co., Ltd.), Shinorine SPE-1150 (sodium polyoxyethylene (1) lauryl ether sulfate), Shinorine SPE-1250 (sodium polyoxyethylene (2) lauryl ether sulfate), Shinorine SPE-1350 (sodium polyoxyethylene (3) lauryl ether sulfate) (all manufactured by New Japan Chemical Co., Ltd.), and Texapon (registered trademark) N70 (sodium polyoxyethylene (2) lauryl ether sulfate) (manufactured by BASF).

-Ether carboxylate-
The ether carboxylate salt in the component (A) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include compounds represented by the following general formula (A2) or (A3): The ether carboxylate salt may be used alone or in combination of two or more types.

In the general formulae (A2) and (A3), ^R2 represents a linear or branched alkyl or alkenyl group having 5 to 23 carbon atoms, or a phenyl group substituted with a linear or branched alkyl or alkenyl group having 5 to 23 carbon atoms, and the number of carbon atoms in the ^R2 moiety is preferably 10 to 14.

In the general formula (A2), ^R3 represents an alkylene group having 2 to 4 carbon atoms, and the number of carbon atoms in the ^R3 portion is preferably 2. The ^R3s may be the same or different.

In the general formula (A2), o represents the average number of moles of alkylene oxide added, ranging from 1 to 20, and the average number of moles of alkylene oxide added is preferably 1 to 5.

In the general formulae (A2) and (A3), M ¹ represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or a basic amino acid.

Specific examples of the ether carboxylate salt represented by the general formula (A2) or (A3) include polyoxyethylene (3) lauryl ether sodium acetate, polyoxyethylene (4) lauryl ether potassium acetate, and sodium lauryl glycol acetate.
The numbers in the parentheses indicate the average number of moles (o) of alkylene oxide added.

The ether carboxylate may be an appropriately synthesized product or a commercially available product.
Commercially available examples of the ether carboxylate include Energicol EC-30 (polyoxyethylene (3) lauryl ether sodium acetate, manufactured by Lion Specialty Chemicals Co., Ltd.), Viewrite LCA-25F (polyoxyethylene (3) lauryl ether sodium acetate), Viewrite LCA-30D (polyoxyethylene (3) lauryl ether sodium acetate), Viewrite LCA-H (polyoxyethylene (4) lauryl ether acetic acid), Viewrite LCA-25NH (laureth-4 carboxylic acid), Viewrite SHAA (sodium lauryl glycol carboxylate), Viewrite LCA (polyoxyethylene (3) lauryl ether sodium acetate) (all manufactured by Sanyo Chemical Industries, Ltd.), Kaoakipo RLM-45NV (polyoxyethylene (4.5) lauryl ether sodium acetate), and Kaoakipo RLM-100NV (polyoxyethylene (10) lauryl ether sodium acetate) (all manufactured by Kao Corporation).
The numbers in the parentheses indicate the average number of moles (o) of alkylene oxide added.

- Amino acid-based surfactants -
The amino acid surfactant in the component (A) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include compounds represented by the following general formula (A4): The amino acid surfactants may be used alone or in combination of two or more.

In the general formula (A4), ^R4 represents a linear or branched alkyl or alkenyl group having 5 to 23 carbon atoms, or a phenyl group substituted with a linear or branched alkyl or alkenyl group having 5 to 23 carbon atoms, and the number of carbon atoms in the ^R4 moiety is preferably 8 to 18.

In the general formula (A4), R ⁵ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

In the general formula (A4), R ⁶ and R ⁷ represent a hydrogen atom or —(CH ₂ ) _m —COOM ^2. R ⁶ and R ⁷ may be the same or different.

In general formula (A4), m and n represent numbers from 0 to 20. m and n may be the same or different.

In the general formula (A4), ^M1 and ^M2 each represent a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or a basic amino acid. ^M1 and ^M2 may be the same or different.

The amino acid structure of the hydrophilic portion of the amino acid surfactant is not particularly limited and can be selected appropriately depending on the purpose, but glycine, glutamic acid, and methylalanine are preferred.

Specific examples of amino acid surfactants represented by the general formula (A4) include N-acylglycines and salts thereof, such as potassium N-cocoylglycine (potassium N-cocoylglycine) and sodium N-cocoylglycine (sodium N-cocoylglycine); N-acyl-N-carboxyethylglycines and salts thereof, such as sodium N-myristoyl-N-carboxyethylglycine; sodium N-myristoyl-L-glutamate, sodium N-lauroyl-L-glutamate, potassium N-myristoyl-L-glutamate, potassium N-cocoyl acyl-L-glutamate, sodium N-cocoyl acyl-L-glutamate, and N-palm fatty acyl- Examples include N-acyl glutamic acids and salts thereof, such as sodium L-glutamate and sodium N-stearoyl-L-glutamate; N-acyl-N-methyl-β-alanines and salts thereof, such as potassium N-lauroyl-N-methyl-β-alanine, sodium lauroylmethyl-β-alanine, N-lauroyl-N-methyl-β-alanine triethanolamine, sodium coconut oil fatty acid methylalanine, and N-coconut oil fatty acid acyl-DL-alanine triethanolamine; N-acyl-β-alanines and salts thereof, such as N-cocoyl-β-alanine triethanolamine; and acyl sarcosines and salts thereof, such as coconut oil fatty acid sarcosine triethanolamine and sodium myristoyl methylaminoacetate.

The amino acid-based surfactant may be suitably synthesized or may be a commercially available product.
Commercially available amino acid surfactants include, for example, trade names such as Amirite (registered trademark) GCK-11 (potassium N-cocoylglycine), Amirite (registered trademark) GCK-12K (potassium N-cocoylglycine), Amirite (registered trademark) GCS-12K (sodium N-cocoylglycine), Amirite (registered trademark) GCS-11 (sodium N-cocoylglycine), Amisoft (registered trademark) CS-11 (sodium N-myristoyl-L-glutamate), Amisoft (registered trademark) CS-22 (sodium N-cocoyl-L-glutamate), Amisoft (registered trademark) LS-11 (sodium N-lauro ...CS-22 (sodium N-cocoyl-L-glutamate), Amisoft (registered trademark) CS-22 (sodium N-cocoyl-L-glutamate), Amisoft (registered trademark) CS-22 (sodium N-cocoyl-L-glutamate), Amisoft (registered trademark) CS-22 (s Sodium glutamate), Amisoft® MS-11 (N-myristoyl-L-glutamate), Amisoft® HS-11P (N-stearoyl-L-glutamate), Amisoft® HS-11P(F) (N-stearoyl-L-glutamate), Amisoft® HS21 (N-stearoyl-L-glutamate disodium), Amirite® ACS-12 (cocoyl alanine sodium) (all manufactured by Ajinomoto Healthy Supply Co., Ltd.), AminoSurfact® AMMS-P1 (N-myristoyl-L-glutamate) (manufactured by Asahi Kasei Chemicals Corporation), NIKKOL Examples of such an active ingredient include Sarcosinate MN (sodium myristoylmethylaminoacetate), NIKKOL Alaninate LN-30 (sodium lauroylmethyl-β-alanine) (all manufactured by Nikko Chemicals Co., Ltd.), Alanon ACE (sodium coconut oil fatty acid methylalanine), Alanon AME (sodium myristoylmethyl-β-alanine), Alanon ALE (sodium lauroylmethyl-β-alanine) (all manufactured by Kawaken Fine Chemicals Co., Ltd.), Enerdicol L-30AN (sodium lauroylmethyl-β-alanine) (manufactured by Lion Specialty Chemicals Co., Ltd.), and Softilt AT-L (sodium lauroylmethyl-β-alanine) (manufactured by NOF Corporation).

The content of the anionic surfactant in component (A) is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoints of foam quality, feel after washing, and bactericidal activity against E. coli, it is preferably 3% to 14% by mass, and more preferably 5% to 12% by mass, based on the total amount of the skin cleanser composition. When the content of component (A) is 3% by mass or more, the foam quality, feel after washing, and bactericidal activity against E. coli are good, and when it is 14% by mass or less, the stability, particularly low-temperature stability, is good.

<(B) At least one plant extract selected from a Sasa kurilensis extract and a water extract of mint>
The plant extract as component (B) is at least one selected from the group consisting of a Sasa kurilensis extract and a water extract oil of peppermint, and is contained mainly to improve the bactericidal activity against Escherichia coli.

-Sasa kurilensis extract-
Sasa kurilensis , used as the raw material for the extraction of the Sasa kurilensis extract, is a monocotyledonous plant belonging to the genus Sasa in the subfamily Bambusoideae of the family Poaceae . It grows wild or is cultivated widely in Japan and is readily available.

The Sasa kurilensis used as the extraction raw material may be a variant of Sasa kurilensis.
The varieties of the Kurile Sasa are not particularly limited as long as they can produce the effects of the present invention and can be appropriately selected depending on the purpose, and examples include Kiakebononemagari, Gintai chishima, Kintaichishima, Kinmei chishima, Shimofurinemagari, Takaranemagari, Chabokonshimachishima, Chabomakiba, Chaboshimofurichishima, Nochizaekifunemagari, Makibanemagari, Miirochishima, Ezonemagari variety, Nagabanemagaridake, etc. These may be used alone or in combination of two or more.
In this specification, Sasa kurilensis and its varieties are collectively referred to as "Sasa kurilensis species." Furthermore, an extract of the Sasa kurilensis species is referred to as "Sasa kurilensis extract."
The method for obtaining the Sasa kurilensis species is not particularly limited and can be appropriately selected depending on the purpose. The species may be collected from nature or may be commercially available.

The Sasa kurilensis extract can be easily obtained using methods commonly used for plant extraction, but in terms of bactericidal activity against E. coli and liquid appearance, extraction methods such as steam distillation and compression extraction are preferred, with purified products of the extract being even more preferred. These extraction methods may be used alone or in combination of two or more.

The part of the Sasa kurilensis plant used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. Examples include above-ground parts such as flowers, buds, fruits, pericarp, seeds, seed coats, stems, leaves, branches, and foliage; and underground parts such as roots and rhizomes. These may be used alone or in combination of two or more. Of these, above-ground parts are preferred as the part of the Sasa kurilensis plant used.

There are no particular restrictions on the size of the Sasa kurilensis used as the extraction raw material, and it can be selected appropriately depending on the purpose. Examples include the size as collected, cut to the desired size, or pulverized (powdered) size.

The state of the Sasa kurilensis used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. For example, it may be in the state as collected, dried, or crushed.

The method for drying the Sasa kurilensis species used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. Examples include drying in the sun and drying using a commonly used dryer.

The method for pulverizing the Sasa kurilensis species used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. Examples include pulverization using a mixer, sugar mill, power mill, jet mill, impact crusher, etc.

When the Sasa kurilensis extract is prepared by steam distillation, the water used as the extraction solvent is not particularly limited and can be selected appropriately depending on the purpose. Examples include pure water, tap water, well water, mineral water, hot spring water, spring water, fresh water, purified water, hot water, ion-exchanged water, saline solution, phosphate buffer solution, and phosphate-buffered saline solution. These may be used alone or in combination of two or more.

There are no particular restrictions on the amount of extraction solvent used, and it can be selected appropriately depending on the purpose.

The extraction conditions for the Sasa kurilensis extract (extraction time, extraction temperature, atmospheric conditions such as pressure, etc.) are not particularly limited and can be appropriately selected from known methods depending on the purpose.
In the case of the compression extraction method, it is preferable to carry out the extraction at low temperature and high pressure, and generally, the extraction is carried out at a temperature of 70° C. or less and under reduced pressure of 100 mmHg to 700 mmHg.

The state of the Sasa kurilensis extract is not particularly limited and can be selected appropriately depending on the purpose. For example, it may be the Sasa kurilensis extract itself, a crude or purified product of the Sasa kurilensis extract, a concentrate of the Sasa kurilensis extract, a diluted product of the Sasa kurilensis extract, or a dried product of the Sasa kurilensis extract. The Sasa kurilensis extract may also be obtained by mixing or dissolving the dried product of the Sasa kurilensis extract in water again.

Among these, the Sasa kurilensis extract is preferably Sasa kurilensis water obtained by extracting and purifying Sasa kurilensis by low-temperature, high-pressure compression extraction.
Examples of commercially available products of such Kumazasa extract include Aqua Aroma Kumazasa (manufactured by Arista Health and Nutrition Science Co., Ltd.) and Kumazasa Water K2-C (manufactured by Nippon Haruma Co., Ltd.).

The content of the Sasa kurilensis extract is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of bactericidal activity against E. coli, it is preferably 0.5% to 1.5% by mass, and more preferably 0.5% to 1.2% by mass, relative to the total amount of the skin cleanser composition. When the content of the Sasa kurilensis extract is 0.5% by mass or more or 1.5% by mass or less, the bactericidal activity against E. coli is good.

- Mint extract -
The mint used as the raw material for the aqueous extract of mint is a plant belonging to the genus Mentha in the family Lamiaceae , and most species are perennials, but there are also annual species. It grows wild or is cultivated widely in Japan, and is easily available.

The plants belonging to the genus Mentha are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include Japanese mint (also known as Japanese mint), water mint, bergamot mint, green mint, common mint, and American mint. These may be used alone or in combination of two or more. Among these, Japanese mint and American mint are preferred.
The method for obtaining the Mint plant is not particularly limited and can be appropriately selected depending on the purpose. The plant may be collected from nature or may be a commercially available product.

The above-mentioned water extract of mint can be easily obtained using methods commonly used for plant extraction, but in terms of its bactericidal activity against E. coli and liquid appearance, an extract extracted and purified by steam distillation is preferred.

The part of the Mint plant used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. Examples include above-ground parts such as flowers, buds, fruits, pericarp, seeds, seed coats, stems, leaves, branches, and foliage; and underground parts such as roots and rhizomes. These may be used alone or in combination of two or more. Of these, above-ground parts are preferred as the part of the Mint plant.

There are no particular restrictions on the size of the Mint plant used as the extraction raw material, and it can be selected appropriately depending on the purpose. Examples include the size as collected, cut to the desired size, or finely pulverized (powdered) size.

The state of the Mint plant used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. Examples include the state as collected, dried, crushed, or squeezed juice.

The method for drying the Mint plant used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. Examples include drying in the sun and drying using a commonly used dryer.

The method for pulverizing the Mentha plant used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose. Examples include pulverization using a mixer, sugar mill, power mill, jet mill, impact pulverizer, etc.

The method for extracting juice from the Mint plant used as the extraction raw material is not particularly limited and can be selected appropriately depending on the purpose, and examples include squeezing.

The water used as the extraction solvent for the water extract of mint is not particularly limited and can be selected appropriately depending on the purpose. Examples include pure water, tap water, well water, mineral water, hot spring water, spring water, fresh water, purified water, hot water, ion-exchanged water, saline solution, phosphate buffer solution, and phosphate-buffered saline solution. These may be used alone or in combination of two or more.

There are no particular restrictions on the amount of extraction solvent used, and it can be selected appropriately depending on the purpose.

The extraction conditions for the water extract of mint (extraction time, extraction temperature, atmospheric conditions such as pressure, etc.) are not particularly limited and can be appropriately selected from known methods depending on the purpose.

The state of the mint water extract is not particularly limited and can be selected appropriately depending on the purpose. For example, it may be the mint water extract itself, a crude or purified product of the mint water extract, a concentrate of the mint water extract, a diluted product of the mint water extract, or a dried product of the mint water extract. The mint water extract may also be obtained by mixing or dissolving the dried mint water extract in water again.

Among these, the water extract of mint is preferably mint oil extracted and purified by steam distillation from a plant belonging to the genus Mint.
Examples of commercially available water extracts of such mint include mint oil (manufactured by Suzuki Mint Co., Ltd.) and mint white oil (manufactured by Nagaoka Jitsugyo Co., Ltd.).

The content of the mint water extract is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoints of bactericidal activity against E. coli and odor, it is preferably 0.1% to 0.6% by mass, and more preferably 0.2% to 0.5% by mass, relative to the total amount of the skin cleanser composition. When the content of the mint water extract is 0.1% by mass or more, the bactericidal activity against E. coli is good, and when it is 0.6% by mass or less, the characteristic odor can be suppressed.

<(C) At least one polyhydric alcohol selected from glycerin, 1,3-butylene glycol, and propylene glycol>
The polyhydric alcohol as component (C) is contained mainly to improve the foam quality and the feel after washing.

The polyhydric alcohol of component (C) is at least one selected from glycerin, 1,3-butylene glycol, and propylene glycol.

The polyhydric alcohol of the component (C) may be an appropriately synthesized product or a commercially available product.
Examples of commercially available glycerin products as the polyhydric alcohol of component (C) include ELOGLYN R995 (glycerin) (manufactured by LG Household & Health Care), Cosmetic Grade Concentrated Glycerin (manufactured by Miyoshi Oil & Fats Co., Ltd.), and Triol VE (manufactured by Kokyu Alcohol Kogyo Co., Ltd.).

Commercially available 1,3-butylene glycol as the polyhydric alcohol of component (C) includes, for example, High Sugar Cane BG (manufactured by Kokyu Alcohol Kogyo Co., Ltd.).

Commercially available propylene glycol products as the polyhydric alcohol of component (C) include, for example, Cosmetic Propylene Glycol (manufactured by ADEKA) and Propylene Glycol JSQI (manufactured by Dow Chemical).

The content of the polyhydric alcohol in component (C) is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoints of foam quality and post-rinse feel, it is preferably 3% to 12% by mass, and more preferably 5% to 10% by mass, relative to the total amount of the skin cleanser composition. When the content of component (C) is 3% by mass or more, the foam quality and post-rinse feel are good, and when it is 12% by mass or less, the foam quality and post-rinse feel are good.

<Mass ratio [(C)/(B)]>
The mass ratio [(C)/(B)] of the content (mass%) of the component (C) to the content (mass%) of the component (B) is 3 to 30, preferably 5 to 25, in order to achieve high bactericidal activity against Escherichia coli and low bactericidal activity against Staphylococcus epidermidis (a normal skin flora). If the mass ratio [(C)/(B)] is less than 3 or exceeds 30, the bactericidal activity against Escherichia coli decreases.

<(D) Amphoteric Surfactant>
The amphoteric surfactant as component (D) is contained mainly to improve foam quality.

The amphoteric surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include alkylbetaine-type amphoteric surfactants, amidobetaine-type amphoteric surfactants, sulfobetaine-type amphoteric surfactants, hydroxysulfobetaine-type amphoteric surfactants, amidosulfobetaine-type amphoteric surfactants, phosphobetaine-type amphoteric surfactants, imidazoline-type amphoteric surfactants, and amine oxide-type amphoteric surfactants. These may be used alone or in combination of two or more.

The alkyl betaine amphoteric surfactant is not particularly limited and can be selected appropriately depending on the purpose. Examples include lauryl dimethylaminoacetic acid betaine and lauryl betaine. These may be used alone or in combination of two or more.

The amidobetaine amphoteric surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include lauric acid amidopropyl betaine (lauramidopropyl betaine), stearyl dimethylaminoacetic acid betaine, and cocamidopropyl betaine (coconut oil fatty acid amidopropyl betaine). These may be used alone or in combination of two or more.

The sulfobetaine-type amphoteric surfactant is not particularly limited and can be selected appropriately depending on the purpose. Examples include coconut oil fatty acid dimethyl sulfopropyl betaine. These may be used alone or in combination of two or more types.

The hydroxysulfobetaine-type amphoteric surfactant is not particularly limited and can be selected appropriately depending on the purpose. Examples include lauryl hydroxysultaine. These surfactants may be used alone or in combination of two or more.

The amidosulfobetaine-type amphoteric surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include cocamidopropyl hydroxysultaine and lauramidopropyl hydroxysultaine. These may be used alone or in combination of two or more.

The phosphobetaine-type amphoteric surfactant is not particularly limited and can be selected appropriately depending on the purpose. Examples include lauryl hydroxyphosphobetaine. These surfactants may be used alone or in combination of two or more.

The imidazoline-type amphoteric surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include coconut oil alkyl-N-hydroxyethyl imidazolinium betaine and 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine. These may be used alone or in combination of two or more.

The amine oxide amphoteric surfactant is not particularly limited and can be selected appropriately depending on the purpose. Examples include lauryl dimethylamine oxide and coconut oil alkyl dimethylamine oxide. These may be used alone or in combination of two or more.

The amphoteric surfactant of the component (D) may be an appropriately synthesized product or a commercially available product.
Commercially available amphoteric surfactants of component (D) include, for example, trade names such as NIKKOL AM-3130N (cocamidopropyl betaine, manufactured by Nikko Chemicals Co., Ltd.), TEGO Betaine (cocamidopropyl betaine, manufactured by Evonik), Amphitol 20AB (lauric acid amidopropyl betaine, manufactured by Kao Corporation), MITAINE L (lauryl betaine, manufactured by Miwon Commercial), Amphorex LSB (lauryl hydroxysultaine, manufactured by Miyoshi Oil & Fats Co., Ltd.), Amphitol 20HD (lauryl hydroxysultaine, manufactured by Kao Corporation), Softazoline LSB (lauramidopropyl hydroxysultaine, manufactured by Kawaken Fine Chemicals Co., Ltd.), and Softazoline. Examples of suitable amine compounds include CH (2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, manufactured by Kawaken Fine Chemicals Co., Ltd.), Amphitol 20N (lauryl dimethylamine oxide, manufactured by Kao Corporation), and Unisafe (registered trademark) A-LM (lauryl dimethylamine oxide, manufactured by NOF Corporation).

The content of the amphoteric surfactant in component (D) is not particularly limited and can be selected appropriately depending on the purpose. However, from the standpoints of foam quality and non-irritation to hand skin, it is preferably 0.1% to 5% by mass, and more preferably 0.5% to 4% by mass, of the total amount of the skin cleanser composition. A content of component (D) of 0.1% by mass or more results in good foam quality, and a content of 5% by mass or less results in good non-irritation to hand skin.

<Other ingredients>
In addition to the components (A), (B), (C), and (D), the skin cleanser composition of the present invention may contain, as necessary, other components that are typically used in skin cleanser compositions, etc., within the scope of the present invention.

The other components are not particularly limited and can be selected appropriately depending on the purpose. Examples of the other components include silicones, moisturizers, anionic surfactants other than component (A) (e.g., sodium polyoxyethylene alkyl ether sulfate, etc.), nonionic surfactants (e.g., polyoxyethylene alkyl ether, etc.), cationic surfactants (e.g., stearyltrimethylammonium chloride, etc.), anti-inflammatory agents (e.g., dipotassium glycyrrhizinate, glycyrrhetinic acid, allantoin, etc.), vitamins, cationic polymers (e.g., cationized cellulose, cationized guar gum, polydimethyldimethylenepyrrolidinium chloride (polyquaternium-6), dimethyldiallylammonium chloride-acrylamide copolymer, etc.), amphoteric polymers (e.g., acrylic acid /dimethyldiallylammonium copolymer, etc.), anionic polymers (e.g., acrylic acid-based polymers, etc.), animal extracts or derivatives thereof, plant extracts or derivatives thereof other than component (B), pearlizing agents, colorants, scrubbing agents (e.g., polyethylene, etc.), fragrances, coloring agents, pigments, preservatives other than component (B) (e.g., methylparaben, phenoxyethanol, etc.), sugars, oils, lanolin derivatives, protein derivatives, acrylic resin dispersions, antioxidants, sequestering agents, UV absorbers, humectants (e.g., sorbitol, etc.), emulsifiers (e.g., steareth-11, trideceth-8, octyldodeceth-5, etc.), chelating agents (e.g., EDTA-4Na, etc.), pH adjusters (e.g., potassium hydroxide, monoethanolamine, etc.), solvents (e.g., water, etc.), etc.

- pH -
The pH of the skin cleanser composition at 25° C. is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 8.0 to 12.0, more preferably 8.5 to 11.0.
The pH can be measured, for example, using a pH meter (HM-30V, manufactured by DKK-TOA Corporation).

-container-
The skin cleanser composition of the present invention is not particularly limited, and is filled into a conventional container for use.
The container is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include pump dispenser containers, tube containers, former containers, squeeze containers, bag-shaped containers, etc. Among these, former containers are preferred.

The foamer container is not particularly limited and can be appropriately selected from known foamer containers. Examples include non-gas foamer containers and aerosol containers that use a propellant and a pressure-resistant container. Of these, non-gas foamer containers are preferred.

The non-gas foam-dispensing container is not particularly limited as long as it can mix the skin cleanser composition with air and dispense it in a foamed state, and can be appropriately selected depending on the purpose. Examples include squeeze foamer containers that can dispense foam by manually squeezing the bottle body, and pump foamer containers that can dispense foam by depressing the nozzle. Such foamer containers can be manufactured by Yamato Seikan Co., Ltd., Yoshino Kogyosho Co., Ltd., and others. More specifically, foamer containers such as those described in JP-A-7-315463, JP-A-8-230961, and JP-A-2005-193972 can be used.

The non-gas type foam dispensing container usually has a foam forming member for forming foam.
Specific examples of the non-gas type foam-discharging container include those having a porous membrane (preferably made of a plastic material such as nylon, polyester, or polyolefin), in which foam is formed when the skin cleanser composition passes through the porous membrane.

The mesh of the porous membrane is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 100 mesh or more, more preferably 100 mesh to 400 mesh, and particularly preferably 200 mesh to 305 mesh.
The number of porous membrane bodies is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of improving foam performance, 2 to 4 membrane bodies are preferred.

-Properties-
The state of the skin cleanser composition is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably liquid at room temperature.
The viscosity of the skin cleanser composition at 25°C is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 mPa s to 30 mPa s, and more preferably 3 mPa s to 30 mPa s. When the viscosity is 1 mPa s or more or 30 mPa s or less, good foam quality is obtained.
Furthermore, when using a foamer container, for example, a pump foamer container capable of discharging foam by depressing a nozzle part, and two 200-mesh porous membrane bodies, the viscosity of the skin cleanser composition under the temperature conditions used is preferably 15 mPa s or less, and more preferably 1 mPa s to 10 mPa s.
Here, the viscosity can be measured, for example, using a Brookfield viscometer by setting the temperature of the skin cleanser composition to 25°C and measuring the viscosity after 1 minute using a No. 1 rotor at a rotation speed of 60 rpm.

-Manufacturing method-
The method for producing the skin cleanser composition of the present invention is not particularly limited and can be appropriately selected depending on the purpose, and can be obtained, for example, by mixing the (A), (B), (C), and (D) components, and further, if necessary, the other components, and purified water (blended as the remainder so that the total amount of the skin cleanser composition becomes 100% by mass). When mixing, heating may be performed, if necessary.

The skin cleanser composition may be prepared using an apparatus that is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a stirring apparatus equipped with stirring blades that exert shear force and can mix the entire composition.
The stirring blade is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a propeller, a turbine, and a disperser.

-Applications-
The area where the skin cleanser composition is applied is not particularly limited and can be appropriately selected depending on the purpose. For example, the skin cleanser composition can be applied to the whole body, face, hands, etc.
The method of using the skin cleanser composition is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable to fill the composition into a foamer container and discharge it in the form of foam.

The skin cleanser composition has high bactericidal activity against pathogenic bacteria such as Escherichia coli while preserving the normal flora that enhances the skin's barrier function. It is colorless, has a good liquid appearance, is free of unpleasant odors and tastes, and is excellent in foam quality, post-cleansing feel, non-irritation to the hands and skin, and stability. Therefore, it can be used in, for example, body shampoo, body soap, facial cleanser, liquid hand soap, foam hand soap, cleansing foam, makeup remover, and the like, and is particularly suitable for use in liquid hand soap that is dispensed in foam form.

The present invention will be explained in detail below using examples, comparative examples, and formulation examples, but the present invention is not limited to these examples and formulation examples in any way.

The content of each component in the examples, comparative examples, and formulation examples is expressed in mass %, and is a value converted to a pure content. Furthermore, the mass ratio of the content (mass %) of component (C) to the content (mass %) of component (B) [(C)/(B)] is rounded to one decimal place and is reported to one decimal place.

(Examples 1 to 32 and Comparative Examples 1 to 12)
<Preparation of Skin Cleanser Composition>
At 70°C to 80°C, components (A), (C), and (D) were uniformly dissolved in purified water and the common components, with the compositions and contents (mass%) shown in Tables 1 to 6 below. The solution was then cooled to 40°C or below, and component (B) or a comparative component for component (B) was added, followed by stirring until uniform, to obtain a solution. Potassium hydroxide was then added appropriately to the solution while stirring, to adjust the pH to a predetermined level. Purified water was then added to each solution so that the total amount was 100% by mass, to obtain the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12.
As shown in Table 7 below, component (B) "peppermint oil" is an extract obtained by steam distillation extraction, component (B) "Kurile Sasa water" is an extract obtained by compression extraction, and the comparative component of component (B) is a solvent extract using butylene glycol or ethanol as the extraction solvent.

For each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12, the following criteria were evaluated and judged: "bactericidal activity against Escherichia coli," "liquid appearance," "odor," "foam quality" (foam elasticity, foam creaminess, and foam persistence), "feel after cleansing" (refreshing feeling after rinsing and moist feeling after rinsing), "non-irritation to hands," and "stability" (low-temperature stability, high-temperature stability, and pH). Furthermore, for each of the skin cleanser compositions of Examples 1 to 32, the "bactericidal activity against Staphylococcus epidermidis" was evaluated and judged as follows. The results are shown in Tables 1 to 6 below.

<Bactericidal effect against E. coli>
(1) Preparation of bacterial solution A representative infectious disease-causing Escherichia coli ( Escherichia coli NBRC3972: Gram-negative bacterium, obtained from the National Institute of Technology and Evaluation) was statically cultured in SCDLP medium (manufactured by Nippon Pharmaceutical Co., Ltd.) under aerobic conditions at 30°C for 24 hours. Next, the E. coli was suspended in physiological saline (manufactured by Otsuka Pharmaceutical Co., Ltd.) and the initial cell count was adjusted to ¹⁰ cells/mL to prepare a bacterial solution.

(2) Preparation of Test Solutions Each of the skin cleansing compositions of Examples 1 to 32 and Comparative Examples 1 to 12 was diluted 10 times with sterilized water to prepare each test solution.

(3) Evaluation method At 25 ° C., 0.1 mL of the bacterial solution obtained in (1) was added to 10 mL of each test solution obtained in (2) above and thoroughly stirred. 30 seconds after the addition of (1), 0.3 mL of the mixed solution was removed and added to 2.7 mL of SCDLP agar medium (Soybean-Casein Digest Broth with Lectin & Polysorbate 80, manufactured by Wako Pure Chemical Industries, Ltd.) to obtain a 10-fold dilution. The same method was repeated to obtain 10 ^2- fold, 10 ^3- fold, and 10 ^4- fold dilutions of the bacterial solution. 1.0 mL of each dilution was placed in a petri dish, 15 mL of SCDLP agar medium was added, homogenized, and cultured at 30 ° C. for 1 day. The number of colonies was counted to determine the number of surviving bacteria (agar plate dilution method). The difference (Δlog ₁₀ ) between the initial number of bacteria and the number of surviving bacteria was calculated using the following formula (1), and the "bactericidal activity against Escherichia coli" was determined based on the following criteria. Note that a larger value calculated using the following formula (1) indicates a higher bactericidal activity.
Killing number Δlog ₁₀ =−log ₁₀ (number of surviving bacteria/number of initial bacteria) Equation (1)
- Criteria for determining "bactericidal activity against E. coli" -
◎: Δlog ₁₀ is 2.7 or more ○: Δlog ₁₀ is 2.5 or more and less than 2.7 △: Δlog ₁₀ is 2.0 or more and less than 2.5 ×: Δlog ₁₀ is less than 2.0

<Liquid appearance>
Immediately after preparation, 50 g of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a hard glass vial, and one expert panelist visually observed the liquid appearance and judged the "liquid appearance" based on the following criteria.
- Criteria for "Liquid Appearance" -
◎: The liquid is clear. ○: The liquid is slightly yellow. △: The liquid is yellow. ×: The liquid is brown.

<Smell>
Immediately after preparation, 50 g of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a hard glass vial, and three expert panelists evaluated the "odor" based on the following criteria. The results were calculated by calculating the average score of the three expert panelists and judging based on the following criteria.
- Evaluation criteria for "odor" -
5: No specific odor at all 4: A slight specific odor is detected 3: A moderate specific odor is detected 2: A significant specific odor is detected, but it is not an unpleasant odor 1: A strong specific odor is detected and it is an unpleasant odor - Criteria for judging "odor" -
◎: Average evaluation score is 4.0 points or more ○: Average evaluation score is 3.0 points or more but less than 4.0 points △: Average evaluation score is 2.0 points or more but less than 3.0 points ×: Average evaluation score is less than 2.0 points

<Foam quality>
Each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a foamer container (manufactured by Yoshino Kogyosho Co., Ltd.). Three expert panelists evaluated (1) "foam elasticity," (2) "foam creaminess," and (3) "foam durability" of each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 filled into the container using the following methods. The average evaluation scores of the three expert panelists were calculated for each item, and the total score of the average evaluation scores for the three items was calculated. The "foam quality" was then judged based on the following criteria.
- Criteria for determining "foam quality" -
◎: The total average evaluation points for (1) to (3) is 12.0 points or more, and the average evaluation point for all items (1) to (3) is 4 points or more. ○: The total average evaluation points for (1) to (3) is 9.0 points or more and less than 12.0 points, and the average evaluation point for all items (1) to (3) is 3 points or more. △: The total average evaluation points for (1) to (3) is 6.0 points or more and less than 9.0 points, and the average evaluation point for all items (1) to (3) is 2 points or more for all items. ×: The total average evaluation points for (1) to (3) is less than 6.0 points.

(1) Foam Elasticity Three expert panelists wet both hands with water, shook them once to lightly dry them, and then dispensed 1 g (1 push) of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 from a foamer container onto the palm of their right hand at 25° C. The panelists rubbed their palms together in a back-and-forth motion, rubbing both hands back and forth 10 times, and then pressed their left hand against the foam collected in the palm of their right hand to evaluate "foam elasticity" according to the following evaluation criteria.
- Evaluation criteria for "foam elasticity" -
5 points: Very elastic foam 4 points: Elastic foam 3 points: Somewhat elastic foam 2 points: Somewhat inelastic foam 1 point: Almost no elastic foam

(2) Foam Creaminess Three expert panelists wet both hands with water, shook them once to lightly dry them, and then dispensed 1 g (1 push) of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 from a foamer container onto the palm of their right hand at 25° C. The panelists rubbed their palms back and forth with their hands together, and after rubbing their hands back and forth 10 times, the appearance of the foam was visually observed, and the "foam creaminess" was evaluated based on the feel during use according to the following evaluation criteria.
- Evaluation criteria for "creamy foam" -
5 points: Most of the bubbles were fine, and it was very creamy. 4 points: Some large bubbles were mixed in with the fine bubbles, but it was still creamy. 3 points: About half of the large bubbles were mixed in with the fine bubbles, and it was somewhat creamy. 2 points: There were more large, coarse bubbles than fine bubbles, and it was not creamy. 1 point: Only large, coarse bubbles were produced, and it was not creamy at all.

(3) Foam Durability Three expert panelists wet both hands with water, shook them once to lightly dry them, and then dispensed 1 g (1 push) of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 from a foamer container onto the palm of their right hand at 25°C. The panelists placed their palms together and rubbed them back and forth, rubbing them back and forth 10 times, and then allowed to stand for 10 seconds. The foam volume (Fa) immediately after rubbing the hands back and forth 10 times and the foam volume (Fb) after leaving the hands to stand for 10 seconds after rubbing were visually observed, and the "foam durability" was evaluated based on the following evaluation criteria.
- Evaluation criteria for "creamy foam" -
5 points: No change at all between the foam volume (Fa) and the foam volume (Fb) 4 points: Almost no change between the foam volume (Fa) and the foam volume (Fb) 3 points: The foam volume (Fb) is reduced compared to the foam volume (Fa) 2 points: The foam volume (Fb) is significantly reduced compared to the foam volume (Fa) 1 point: No foam remains on the hands for either the foam volume (Fa) or the foam volume (Fb)

<Feel after washing>
Each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a former container (manufactured by Yoshino Kogyosho Co., Ltd.). Three expert panelists evaluated (1) "refreshing feeling after rinsing" and (2) "moist feeling after rinsing" of each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 filled into the containers using the following methods. The average evaluation scores of the three expert panelists were calculated for each item, and the total score of the average evaluation scores for (1) and (2) was calculated. The "feel after cleansing" was then judged based on the following criteria.
- "Feel after washing" evaluation criteria -
◎: The total of the average evaluation points for (1) and (2) is 8.0 points or more. ○: The total of the average evaluation points for (1) and (2) is 7.0 points or more but less than 8.0 points. △: The total of the average evaluation points for (1) and (2) is 5.0 points or more but less than 7.0 points. ×: The total of the average evaluation points for (1) and (2) is less than 5.0 points.

(1) Refreshing Feeling After Rinsing Three expert panelists wet both hands with water, shook them once to lightly dry them, and then dispensed 1 g (1 push) of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 from a foamer container onto the palm of their right hand at 25° C. The panelists placed their palms together and rubbed them back and forth for 10 seconds, after which they rinsed their hands with tap water (25° C., 2 L/min). When each expert panelist determined that rinsing was complete, the panelists evaluated the "refreshing feeling after rinsing" according to the following criteria.
- Evaluation criteria for "refreshing feeling after rinsing" -
5 points: Very refreshing 4 points: Refreshing 3 points: Somewhat refreshing 2 points: Not very refreshing 1 point: Not refreshing at all

(2) Moisturizing Feeling After Rinsing Three expert panelists wet both hands with water, shook them once to lightly dry them, and then dispensed 1 g (1 push) of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 from a foamer container onto the palm of their right hand at 25° C. The panelists placed their palms together and rubbed them back and forth for 10 seconds, then rinsed both hands with tap water (25° C., 2 L/min). When each expert panelist determined that rinsing was complete, the panelists evaluated the "moisturizing feeling after rinsing" based on the following evaluation criteria.
- Evaluation criteria for "moisturizing feeling after rinsing" -
5 points: Very moist 4 points: Moist 3 points: Slightly moist 2 points: Slightly less moist 1 point: Not moist at all

<No irritation to the skin>
Each of the skin cleansing compositions of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a former container (manufactured by Yoshino Kogyosho Co., Ltd.).
Three expert panelists wet both hands with water, shook them once to lightly dry them, and then dispensed 1 g (1 push) of each skin cleanser composition of Examples 1 to 32 and Comparative Examples 1 to 12 from a former container onto the palm of their right hand at 25°C. The panelists placed their palms together and rubbed them back and forth for 10 seconds. After rinsing their hands with tap water (25°C, 2 L/min), they towel-dried them and evaluated the "freedom of irritation to the hands" according to the following evaluation criteria. The results were calculated by calculating the average score of the three expert panelists and judging them according to the following evaluation criteria.
- Evaluation criteria for "non-irritation to hand skin" -
5: No irritation to hands during washing or drying 4: Almost no irritation to hands during washing or drying 3: Slight irritation to hands during washing or drying 2: Irritation to hands during washing or drying 1: Severe irritation to hands during washing or drying - Criteria for determining "no irritation to hands" -
◎: Average evaluation score is 4.0 or more. ○: Average evaluation score is 3.0 or more but less than 4.0. △: Average evaluation score is 2.0 or more but less than 3.0. ×: Average evaluation score is less than 2.0.

<Stability>
The skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 were evaluated for (1) "low-temperature stability," (2) "high-temperature stability," and (3) "pH" by the following methods, and the total points for each of the items (1) to (3) were calculated, and the "stability" was judged based on the following criteria.
- Criteria for determining "stability" -
◎: The total score for (1) to (3) is 12.0 points or more, and all items from (1) to (3) are 3 points or more. ○: The total score for (1) to (3) is 9.0 points or more and less than 12.0 points, and all items from (1) to (3) are 3 points or more. △: The total score for (1) to (3) is 6.0 points or more and less than 9.0 points, and all items from (1) to (3) are 2 points or more. ×: The total score for (1) to (3) is less than 6.0 points.

(1) Low-Temperature Stability 50 g of each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a hard glass vial and stored in an environment at 10°C for one month, or after storing in an environment at 10°C for one month and then returning to 25°C, one expert panelist visually observed the appearance of the liquid and evaluated the "low-temperature stability" based on the following evaluation criteria.
- Evaluation criteria for "low temperature stability" -
5 points: No precipitation at all after 1 month storage at 10°C 4 points: No precipitation when returned to 25°C after 1 month storage at 10°C 3 points: Slight turbidity due to precipitation is observed after returning to 25°C after 1 month storage at 10°C 2 points: Precipitation is observed after returning to 25°C after 1 month storage at 10°C 1 point: A large amount of precipitation is observed after returning to 25°C after 1 month storage at 10°C

(2) High-Temperature Stability 50 g of each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a hard glass vial and stored in an environment of 50°C for one month. After that, one expert panel member visually observed the appearance of the liquid and evaluated its odor, and evaluated the "high-temperature stability" based on the following evaluation criteria.
- Evaluation criteria for "high temperature stability" -
5 points: No change in color or odor after 1 month of storage at 50°C compared to before storage 4 points: Almost no change in color or odor after 1 month of storage at 50°C compared to before storage 3 points: A slight change in color or odor is observed after 1 month of storage at 50°C compared to before storage, but to an extent that does not pose a problem in terms of commercial value 2 points: A change in color or odor is observed after 1 month of storage at 50°C compared to before storage, and there is a problem in terms of commercial value 1 point: A significant change in color or odor is observed after 1 month of storage at 50°C compared to before storage, and there is a problem in terms of commercial value

(3) pH
50 g of each of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12 was filled into a hard glass vial and stored in an environment of 50°C for 1 month. After that, the pH was measured using a pH meter (HM-30V, manufactured by DKK-TOA Corporation), and the "pH" was evaluated based on the following evaluation criteria.
- "pH" evaluation criteria -
5 points: pH change after 1 month at 50°C is within ±0.2 compared to before storage 4 points: pH change after 1 month at 50°C is greater than ±0.2 and within ±0.4 compared to before storage 3 points: pH change after 1 month at 50°C is greater than ±0.4 and within ±0.6 compared to before storage 2 points: pH change after 1 month at 50°C is greater than ±0.6 and within ±0.8 compared to before storage 1 point: pH change after 1 month at 50°C is greater than ±0.8 compared to before storage

<Bactericidal activity against Staphylococcus epidermidis>
Since Staphylococcus epidermidis is a normal inhabitant of the skin with a barrier function, it is preferable that a skin cleanser composition have low bactericidal activity against Staphylococcus epidermidis. Therefore, the bactericidal activity of each of the skin cleanser compositions of Examples 1 to 32 against Staphylococcus epidermidis was evaluated by the following method.

(1) Preparation of bacterial solution Staphylococcus epidermidis ( Staphylococcus epidermidis ATCC12228, obtained from the National Institute of Technology and Evaluation (NBRC)) was subjected to static culture in SCDLP medium (manufactured by Nippon Pharmaceutical Co., Ltd.) under aerobic conditions at 30°C for 24 hours. Next, the Staphylococcus epidermidis was suspended in physiological saline (manufactured by Otsuka Pharmaceutical Co., Ltd.) and the initial cell count was adjusted to ¹⁰ cells/mL to prepare a bacterial solution.

(2) Preparation of Test Solutions Each of the skin cleansing compositions of Examples 1 to 32 was diluted 10 times with sterilized water to prepare each test solution.

(3) Evaluation method At 25 ° C., 0.1 mL of the bacterial solution obtained in (1) was added to 10 mL of each test solution obtained in (2) above and thoroughly stirred. 30 seconds after the addition of (1), 0.3 mL of the mixed solution was removed and added to 2.7 mL of SCDLP agar medium (Soybean-Casein Digest Broth with Lectin & Polysorbate 80, manufactured by Wako Pure Chemical Industries, Ltd.) to obtain a 10-fold dilution. The same method was repeated to obtain 10 ^2- fold, 10 ^3- fold, and 10 ^4- fold dilutions of the bacterial solution. 1.0 mL of each dilution was placed in a petri dish, 15 mL of SCDLP agar medium was added, homogenized, and cultured at 30 ° C. for 2 days. The number of colonies was counted to determine the number of surviving bacteria (agar plate dilution method). The difference (Δlog ₁₀ ) between the initial number of bacteria and the number of surviving bacteria was calculated using the following formula (2), and the "bactericidal activity against Staphylococcus epidermidis" was determined based on the following criteria. Note that a larger value calculated using the following formula (2) indicates a higher bactericidal activity.
Killing number Δlog ₁₀ =−log ₁₀ (number of surviving bacteria/number of initial bacteria) Equation (2)
- Criteria for determining "bactericidal activity against Staphylococcus epidermidis" -
◎: Δlog ₁₀ is less than 1.0 ○: Δlog ₁₀ is 1.0 or more and less than 2.0 △: Δlog ₁₀ is 2.0 or more and less than 3.0 ×: Δlog ₁₀ is 3.0 or more

(Prescription Examples 1 to 8)
<Preparation of Skin Cleanser Composition>
The skin cleanser compositions of Formulation Examples 1 to 8 were obtained in the same manner as in the preparation of the skin cleanser compositions of Examples 1 to 32 and Comparative Examples 1 to 12, except that the compositions and contents (% by mass) were changed to those shown in Table 7 below.

Details of each component used in Examples 1-32, Comparative Examples 1-12, and Formulation Examples 1-12 are shown in Table 9 below.

*1: Potassium laurate was prepared by neutralizing lauric acid (Kortacid 1299, manufactured by Pacific Oleochemicals) with potassium hydroxide (POTASSIUM HYDROXIDE 48%, manufactured by UNIDS).
*2: Potassium myristate was prepared by neutralizing myristic acid (Kortacid 1499, manufactured by Pacific Oleochemicals) with potassium hydroxide (POTASSIUM HYDROXIDE 48%, manufactured by UNIDS).

The skin cleanser composition has high bactericidal activity against pathogenic bacteria such as Escherichia coli while preserving the normal flora that enhances the skin's barrier function. It is colorless, has a good liquid appearance, is free of unpleasant odors and tastes, and is excellent in foam quality, post-cleansing feel, non-irritation to the hands and skin, and stability. Therefore, it can be used in, for example, body shampoo, body soap, facial cleanser, liquid hand soap, foam hand soap, cleansing foam, makeup remover, and the like, and is particularly suitable for use in liquid hand soap that is dispensed in foam form.

Claims (3)

(A) a higher fatty acid salt ;
(B) at least one plant extract selected from a Sasa kurilensis extract and a water extract of mint;
(C) at least one polyhydric alcohol selected from glycerin, 1,3-butylene glycol, and propylene glycol;
(D) at least one amphoteric surfactant selected from alkylbetaine amphoteric surfactants and amine oxide amphoteric surfactants;
Contains
The Sasa kurilensis extract is a Sasa kurilensis water obtained by compressing and extracting Sasa kurilensis under a reduced pressure of 100 mmHg to 700 mmHg at an extraction temperature of 70°C or less, and purifying the extract;
The water extract of mint is mint oil obtained by steam distillation and purification of a plant belonging to the genus Mint;
The content of the component (A) is 3% by mass to 14% by mass,
When the component (B) contains the Sasa kurilensis extract, the content of the Sasa kurilensis extract is 0.5% by mass to 1.5% by mass,
When the component (B) contains the water extract of mint, the content of the water extract of mint is 0.1% by mass to 0.6% by mass,
The content of the component (C) is 3% by mass to 12% by mass,
A liquid skin cleanser composition, characterized in that the mass ratio [(C)/(B)] of the content of the component (C) to the content of the component (B) is 3 to 30. The content of the component (A) is 5% by mass to 12% by mass,
When the component (B) contains the Sasa kurilensis extract, the content of the Sasa kurilensis extract is 0.5% by mass to 1.2% by mass,
When the component (B) contains the water extract of mint, the content of the water extract of mint is 0.2% by mass to 0.5% by mass,
2. The liquid skin cleanser composition according to claim 1, wherein the content of the component (C) is 5% by mass to 10% by mass. 3. The liquid skin cleanser composition according to claim 1, wherein the content of the component (D) is 0.5% by mass to 4% by mass.