JP7505864B2 - Skin cleansing composition - Google Patents

Description

The present invention relates to a skin cleansing composition that has reduced skin irritation and excellent cleansing power.

A variety of skin cleansing compositions, such as face washes, body soaps, and shampoos, are available as products designed to cleanse the skin and keep it clean. The mechanism by which skin cleansing compositions cleanse the skin is that the surfactant adsorbs to dirt, reducing the surface tension between the dirt and water, and, together with the mechanical force caused by friction, causes the dirt to float up into the water. For this cleaning mechanism to function effectively, it is necessary to incorporate the surfactant at a concentration equal to or higher than the critical micelle concentration.

On the other hand, surfactants with too strong cleansing power can cause skin irritation, resulting in dry skin and other skin problems. For this reason, various formulas have been proposed that devise combinations and amounts of cleansing ingredients to make the product more mild on the skin. In particular, it is generally accepted that formulas that improve foam quality, such as foaming power and foam retention, are excellent for making the product more mild on the skin, as the foam formed during cleansing is recognized to reduce friction caused by direct contact between the skin and fingers.

For this reason, in recent years, various pump-foamer-type skin cleansers have been proposed, and they have attracted attention not only for their convenience in easily obtaining high-quality foam, but also for their gentleness to the skin. Specifically, Patent Document 1 discloses a liquid skin cleansing product comprising a former container and a liquid skin cleansing composition filled in the former container, the liquid skin cleansing composition containing (A) 3 to 10% by mass of a specific fatty acid salt having a linear or branched monovalent hydrocarbon group having 7 to 21 carbon atoms, (B) a specific copolymer of dimethyldiallylammonium chloride and acrylic acid and/or acrylamide, and (C) a sugar alcohol, and the mass ratio (A)/(B) of the content of component (A) to the content of component (B) is 20 to 250. Patent Document 2 discloses a skin cleansing composition that contains (a) 2 to 9% by mass of a fatty acid salt, (b) 0.5 to 4% by mass of lauryldimethylaminoacetate betaine, and (c) 1 to 10% by mass of one or more dihydric alcohols, and the sum of the amounts (mass%) of the (a) and (b) components (a) + (b) is 3 to 10% by mass, and the ratio of the amounts (b)/(a) is 0.1 to 0.5, and is filled in a former container. Patent Document 3 discloses a cleansing composition that is discharged from a former container and contains (a) lauryldimethylaminoacetate betaine and (b) 4 to 15% by mass of a higher fatty acid soap formed from a fatty acid having 5 to 25 carbon atoms and having a specific composition.

International Publication No. 2014/003114 JP 2016-098182 A International Publication No. 2017/081897

Pump-former-type skin cleansing compositions contain a relatively small amount of surfactant, and in this respect, are thought to tend to cause less irritation to the skin than solid or semi-solid skin cleansing compositions. On the other hand, since the pump-former-type skin cleansing composition is premised on being discharged in a foam state, it is unavoidable from the viewpoint of its composition to contain the minimum amount of surfactant required to exert foaming power.

In recent years, there has been an increasing awareness of the need for face washing that is gentle on the skin. Furthermore, even with conventional skin cleansing compositions, there are still no skin cleansing compositions that are formulated to adequately address sensitive skin that is prone to skin irritation. Therefore, there is a greater demand than ever for skin cleansing compositions that are less irritating to the skin.

In order to further reduce irritation to the skin, the inventors significantly reduced the amount of surfactant contained in the composition compared to the amount contained in conventional skin cleansing compositions. However, with skin cleansing compositions that contain such a significantly smaller amount of surfactant, they faced the problem that they could not obtain cleaning power in exchange for reduced irritation to the skin.

Therefore, the present invention aims to provide a skin cleansing composition that has reduced skin irritation and excellent cleansing power.

As a result of extensive research, the inventors have found that in a skin cleansing composition, the coexistence of a small amount of surfactant with an amphiphilic ester can reduce skin irritation while still providing excellent cleansing power. The present invention was completed through further research based on this finding.

That is, the present invention provides the following aspects.
Item 1. A skin cleansing composition comprising (A) a surfactant and (B) an amphiphilic ester, the content of component (A) being 0.025 to 2% by weight.
Item 2. The skin cleansing composition according to Item 1, wherein the component (B) is selected from the group consisting of dicarboxylic acid bis(polyoxyalkylene alkyl ether) esters and polyglyceryl-10 (eicosadioate/tetradecanedioate).
Item 3. The skin cleansing composition according to Item 2, wherein the dicarboxylic acid bis(polyoxyalkylene alkyl ether) ester is cyclohexane-1,4-dicarboxylate bis(ethoxydiglycol).
Item 4. The skin cleansing composition according to any one of Items 1 to 3, wherein the content of the component (A) is 0.025 to 0.9% by weight.
Item 5. (A) A method for improving the detergency of a skin cleansing composition containing 0.025 to 2% by weight of a surfactant, comprising:
A method for improving detergency, comprising blending an amphiphilic ester (B) together with the component (A) in a skin cleansing composition.

The skin cleansing composition of the present invention can exert excellent cleansing power while reducing skin irritation.

1. Skin Cleansing Composition The skin cleansing composition of the present invention is characterized by containing a predetermined amount of (A) a surfactant (hereinafter, sometimes referred to as component (A)) and (B) an amphiphilic ester (hereinafter, sometimes referred to as component (B)). The skin cleansing composition of the present invention will be described in detail below.

(A) Surfactant The skin cleansing composition of the present invention contains a surfactant as component (A). The surfactant is not particularly limited, but from the viewpoint of suppressing irritation to the skin, preferred examples include anionic surfactants, nonionic surfactants, amphoteric surfactants, natural surfactants, etc. As the surfactant, one of anionic surfactants, nonionic surfactants, amphoteric surfactants, and natural surfactants may be used alone, or two or more of them may be used in any combination.

Examples of anionic surfactants that can be used in the present invention include carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type surfactants.

Specific examples of carboxylic acid type surfactants include saturated or unsaturated fatty acids having 6 to 22 carbon atoms, such as octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, and stearic acid; and N-acylamino acids (carboxylic acid type amino acid anionic surfactants) having saturated or unsaturated N-acyl groups having 8 to 24 carbon atoms, such as octanoyl group, decanoyl group, lauroyl group, myristoyl group, palmitoyl group, and cocoyl group. Examples of N-acylamino acids in carboxylic acid type amino acid anionic surfactants include N-acylsarcosine, N-acylaspartic acid, N-acylglutamic acid, and lauroylmethyl-β-alanine. More specific examples of carboxylic acid type amino acid anionic surfactants include N-lauroylsarcosine, N-lauroylaspartic acid, cocoylglutamic acid,
Examples thereof include sodium lauroylmethyl-β-alanine.

Specific examples of sulfonic acid surfactants include esters of fatty acids having 6 to 22 carbon atoms, such as cocoyl isethionic acid, and isethionic acid; alkyl sulfonic acids having 6 to 22 carbon atoms, such as hexanesulfonic acid, octanesulfonic acid, decane sulfonic acid, and dodecane sulfonic acid; alkyl benzene sulfonic acids having an alkyl group having 10 to 16 carbon atoms, such as alkyl benzene sulfonic acid; and N-acyl-N-methyl taurine (sulfonic acid amino acid anionic surfactant) having a saturated or unsaturated N-acyl group having 8 to 24 carbon atoms, such as an octanoyl group, a decanoyl group, a lauroyl group, a myristoyl group, a palmitoyl group, or a cocoyl group. More specific examples of sulfonic acid amino acid anionic surfactants include N-myristoyl-N-methyl taurine, N-lauroyl methyl taurine, and cocoyl methyl taurine.

Specific examples of sulfate ester type surfactants include esters of saturated or unsaturated fatty acids having 10 to 22 carbon atoms, such as lauryl sulfate and myristyl sulfate, and sulfuric acid.Specific examples of phosphate ester type surfactants include esters of saturated or unsaturated fatty acids having 8 to 24 carbon atoms, such as lauryl phosphoric acid, and phosphoric acid.

These anionic surfactants may be in the form of a salt, for example, an alkali metal salt such as a sodium salt or a potassium salt; a triethanolamine (TEA) salt; an ammonium salt, etc.

Among these anionic surfactants, from the viewpoint of obtaining better skin irritation reduction and cleaning power, preferred are carboxylic acid type surfactants and sulfonic acid type surfactants, more preferred are lauric acid, N-lauroyl aspartic acid, cocoyl glutamic acid, cocoyl methyl taurine and salts thereof, and even more preferred are sodium laurate, sodium N-lauroyl aspartate, triethanolamine cocoyl glutamate and sodium methyl cocoyl taurine. Furthermore, among these, from the viewpoint of obtaining better skin irritation reduction properties, preferably, N-acyl glutamic acid having a saturated or unsaturated acyl group having 8 to 24 carbon atoms, fatty acid amide sulfonic acid having 8 to 22 carbon atoms, and salts thereof are mentioned, more preferably, cocoyl glutamic acid, cocoyl methyl taurine, and salts thereof are mentioned, and even more preferably, triethanolamine cocoyl glutamate, and sodium cocoyl methyl taurine are mentioned, and further, from the viewpoint of obtaining better cleaning power, preferably, N-acylaspartic acid having a saturated or unsaturated acyl group having 8 to 24 carbon atoms is mentioned, more preferably, N-lauroyl aspartic acid is mentioned, and even more preferably, sodium N-lauroyl aspartate is mentioned.

These anionic surfactants may be used alone or in combination of two or more.

Nonionic surfactants that can be used in the present invention include, for example, ester type, ether type, ester-ether type, alkanolamide type, alkyl glycoside type, alcohol type, and other surfactants.

Specific examples of ester-type surfactants include mono- or diesters of saturated or unsaturated fatty acids having 8 to 20 carbon atoms and glycerin, such as glycol dilaurate, glycol monostearate, glycol distearate, glyceryl monolaurate, glyceryl dilaurate, glyceryl monostearate, and glyceryl distearate; sorbitan fatty acid esters; and sucrose fatty acid esters.

Specific examples of ether-type surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polyoxypropylene glycols, etc.

Examples of ester/ether type surfactants include polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene hexitane fatty acid ester, sorbitan fatty acid ester polyethylene glycol, etc.

Specific examples of alkanolamide surfactants include cocamide DEA (coconut oil fatty acid diethanolamide), lauric acid diethanolamide, oleic acid diethanolamide, stearic acid diethanolamide, etc.

Specific examples of alkyl glycoside surfactants include octyl glucoside, decyl glucoside, lauryl glucoside, etc.

Examples of alcohol-based surfactants include cetanol, stearyl alcohol, and oleyl alcohol.

Among these nonionic surfactants, from the viewpoint of obtaining better skin irritation reduction and cleaning power, preferred are ester/ether type surfactants and alkanolamide type surfactants, more preferred are polyoxyethylene hydrogenated castor oil and cocamide DEA, and even more preferred is polyoxyethylene hydrogenated castor oil.

These nonionic surfactants may be used alone or in combination of two or more.

Examples of amphoteric surfactants that can be used in the present invention include alkyl betaine type, fatty acid amidopropyl betaine type, and amine oxide type surfactants.

Specific examples of alkyl betaine type surfactants include lauryl dimethyl amino acetate betaine, stearyl dimethyl amino acetate betaine, octadecyl aminomethyl dimethyl sulfopropyl betaine, etc.

Specific examples of fatty acid amidopropyl betaine type amphoteric surfactants include amidobetaines (amino acid-based amphoteric surfactants) such as cocamidopropyl betaine, and sulfobetaines such as cocamidopropyl hydroxysultaine.

Specific examples of amine oxide amphoteric surfactants include lauryl dimethylamine N-oxide and oleyl dimethylamine N-oxide.

These amphoteric surfactants may be in the form of a salt, for example, an alkali metal salt such as a sodium salt or a potassium salt; a triethanolamine (TEA) salt; an ammonium salt, etc.

Among these amphoteric surfactants, from the viewpoint of reducing skin irritation and obtaining better cleaning power, fatty acid amidopropyl betaine type surfactants are preferred, more preferably amidobetaines (amino acid-based amphoteric surfactants) such as cocamidopropyl betaine, and even more preferably cocamidopropyl betaine.

These amphoteric surfactants may be used alone or in combination of two or more.

The natural surfactants used in the present invention include lecithin and lysolecithin; saponins such as quillaja saponin, soybean saponin, yucca saponin, soybean saponin, beet saponin, adzuki bean saponin, carrot saponin, tea seed saponin, loofah saponin, and Centella saponin.

Lecithin is a mixture of phospholipids such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol, as well as other components such as triglycerides, fatty acids, and carbohydrates from vegetable oils, and is a well-known ingredient in pharmaceuticals, quasi-drugs, and cosmetics.

Lecithin may be natural lecithin derived from animals or plants (e.g., soybean lecithin, egg yolk lecithin, etc.), chemically processed natural lecithin, or purified natural lecithin. Chemically processed natural lecithin includes hydrogenated lecithin obtained by hydrogenation (e.g., fully hydrogenated lecithin and partially hydrogenated lecithin), and hydroxide lecithin obtained by hydroxide treatment. Refined natural lecithin includes lecithin with an increased phosphatidylcholine content using a solvent such as acetone.

Lysolecithin includes the lyso form of the above-mentioned lecithin (natural lecithin, chemically treated natural lecithin, and purified natural lecithin). Lysolecithin has a structure in which the fatty acid at the 2nd position of phosphatidylcholine has been removed by hydrolysis (dissolution) of lecithin with an enzyme such as phospholipase A2.

Among these natural surfactants, from the viewpoint of obtaining better skin irritation reduction and cleaning power, lecithin, lysolecithin, and saponin are preferred, lecithin and lysolecithin are more preferred, and lysolecithin is even more preferred.

These natural surfactants may be used alone or in combination of two or more.

The content of the component (A) in the skin cleansing composition of the present invention is 0.025 to 2% by weight. Such a small amount of surfactant can remarkably reduce skin irritation. In the present invention, excellent cleaning power can be exhibited by coexisting with the component (B), so that even a small amount of surfactant that would not normally be able to exhibit effective cleaning power can effectively exhibit cleaning power. From this viewpoint, the upper limit of the above content range of the component (A) is preferably 1.5% by weight or less, which further reduces skin irritation, more preferably 1% by weight or less, and even more preferably 0.9% by weight or less. From the viewpoint of obtaining a better cleaning power, the lower limit of the above content range of the component (A) is preferably 0.1% by weight or more, and more preferably 0.5% by weight or more.

The skin cleansing composition of the present invention contains an amphiphilic ester as component ( B). Component (B) does not exhibit a cleansing effect alone, but by coexisting with 0.025 to 2% by weight of component (A), the cleansing power of the skin cleansing composition can be improved while maintaining low irritation.

In the present invention, the amphiphilic ester is one that dissolves at 2% by mass or more at room temperature in ion-exchanged water adjusted to a conductivity of 70 to 110 μs/m, as measured by the method specified in the general testing method of the Japanese Pharmacopoeia, and dissolves at 10% by mass or more in the oil agent isotridecyl isononanoate (Salacos 913, manufactured by Nisshin Oillio Group, Ltd.) at room temperature (25°C), and ester-based surfactants are excluded.

The amphiphilic ester is not particularly limited, but from the viewpoint of obtaining better skin irritation reduction properties and cleaning power, it is preferable that it is selected from the group consisting of dicarboxylate bis(polyoxyalkylene alkyl ether) esters and polyglyceryl-10 (eicosane diacid/tetradecanedioic acid). As the amphiphilic ester, any one of dicarboxylate bis(polyoxyalkylene alkyl ether) esters and polyglyceryl-10 (eicosane diacid/tetradecanedioic acid) may be used alone, or both may be used in combination. Among these amphiphilic esters, dicarboxylate bis(polyoxyalkylene alkyl ether) esters are more preferable from the viewpoint of obtaining better skin irritation reduction properties and cleaning power.

The dicarboxylic acid bis(polyoxyalkylene alkyl ether) ester used in the present invention is a diester compound of a dicarboxylic acid and a polyoxyalkylene alkyl ether. Specific examples of the dicarboxylic acid constituting the diester compound of the dicarboxylic acid bis(polyoxyalkylene alkyl ether) ester include, for example, oxalic acid, malonic acid, succinic acid, tartaric acid, malic acid, glutaric acid, adipic acid, pemelic acid, suberic acid, azelaic acid, sebacic acid, aspartic acid, glutamic acid, acetone dicarboxylic acid, phthalic acid, and cyclohexane-1,4-dicarboxylic acid. Examples of the polyoxyalkylene alkyl ether constituting the diester compound include, for example, polyoxyethylene monoalkyl ether, and more specifically, for example, diethylene glycol monoethyl ether and triethylene glycol monoethyl ether.

Among these dicarboxylic acid bis(polyoxyalkylene alkyl ether) esters, from the viewpoint of obtaining better skin irritation reduction properties and cleaning power, preferably, a diester compound of cyclohexane-1,4-dicarboxylic acid and diethylene glycol monoethyl ether, specifically, a compound called cyclohexane-1,4-dicarboxylic acid bisethoxydiglycol, represented by the INCI name (International Cosmetic Ingredient Dictionary and Handbook, 13th Edition, Vol. 1, CTFA, 2010, p. 331): BIS-ETHOXYDIGLYCOL CYCLOHEXANE 1,4-DICARBOXYLATE, and a diester compound of succinic acid and diethylene glycol monoethyl ether, specifically, a diester compound of succinic acid and diethylene glycol monoethyl ether, represented by the INCI name (International Cosmetic Ingredient Dictionary and Handbook, 13th Edition, Vol. 1, CTFA, 2010, p. 331): BIS-ETHOXYDIGLYCOL CYCLOHEXANE 1,4-DICARBOXYLATE, are used. Ingredient Dictionary and Handbook, 13th Edition, Vol. 1, CTFA, 2010, pp. 331-332): A compound called bis-ethoxydiglycol succinate, represented as BIS-ETHOXYDIGLYCOL SUCCINATE, is included, and more preferably bis-ethoxydiglycol cyclohexane-1,4-dicarboxylate is included.

In the present invention, a specific example of the bis-ethoxydiglycol cyclohexane-1,4-dicarboxylate is "Neosolue-Aquilio (trade name)" manufactured by Nippon Fine Chemicals Co., Ltd., and the like. A specific example of the bis-ethoxydiglycol succinate is "Hi-Aquostar DCS (trade name)" manufactured by Kokyu Alcohol Kogyo Co., Ltd., and the like.

These dicarboxylic acid bis(polyoxyalkylene alkyl ether) esters may be used alone or in combination of two or more.

The polyglyceryl-10 (eicosane diacid/tetradecanedioic acid) used in the present invention is not particularly limited, but examples include "Neosolue-Aqua (trade name)" and "Neosolue-AquaS (trade name)" manufactured by Nippon Fine Chemicals Co., Ltd.

The content of component (B) in the skin cleansing composition of the present invention is not particularly limited, but may be, for example, 0.1% by weight or more. From the viewpoint of obtaining better cleaning power, the content of component (B) is preferably 0.5% by weight or more. The upper limit of the range of the content of component (B) is not particularly limited, but from the viewpoint of the stability of the skin cleansing composition, for example, it may be 5% by weight or less, preferably 3% by weight or less, more preferably 2% by weight or less.

In the skin cleansing composition of the present invention, the ratio of component (A) to component (B) is not particularly limited and is determined by the above-mentioned respective contents, but from the viewpoint of obtaining better skin irritation reduction properties and cleaning power, for example, 0.1 to 100 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight of component (B) per 1 part by weight of component (A).

Other Components In addition to the above-mentioned components, the skin cleansing composition of the present invention may contain other bases and additives required for formulation, etc., within the scope of not impairing the effects of the present invention. Such additives are not particularly limited as long as they are pharma- ceutically acceptable, and examples thereof include aqueous bases such as water, lower alcohols having 1 to 5 carbon atoms (ethanol, isopropanol, etc.), and polyhydric alcohols (ethylene glycol, 1,3-butylene glycol (1,3-BG), propylene glycol, isoprene glycol, diethylene glycol, dipropylene glycol, polypropylene glycol, glycerin, etc.); preservatives (methylparaben, propylparaben, benzoic acid, sodium benzoate, sorbic acid, etc.), flavoring agents (citral, 1,8-thioneal, citronellal, farnesol, etc.), colorants (tar dyes (Brown No. 201, Blue No. 201, Yellow No. 4, Yellow No. 403, etc.), cacao dyes, chlorophyll, aluminum oxide, etc.), thickeners (hydroxypropylcellulose, hydroxyethylcellulose, crosslinked acrylic acid polymers, carboxyvinyl polymers, hydroxypropylcellulose ... Examples of additives include promellose, polyvinylpyrrolidone, sodium alginate, ethyl cellulose, sodium carboxymethylcellulose, xanthan gum, carrageenan, etc.), pH adjusters (phosphoric acid, hydrochloric acid, citric acid, sodium citrate, succinic acid, tartaric acid, sodium hydroxide, potassium hydroxide, triethanolamine, triisopropanolamine, etc.), wetting agents (sodium dl-pyrrolidone carboxylate solution, D-sorbitol solution, macrogol, etc.), stabilizers (dibutylhydroxytoluene, butylhydroxyanisole, sodium edetate, sodium metaphosphate, L-arginine, L-aspartic acid, DL-alanine, glycine, sodium erythorbate, propyl gallate, sodium sulfite, sulfur dioxide, chlorogenic acid, catechin, rosemary extract, etc.), antioxidants, ultraviolet absorbers, chelating agents, adhesives, buffers, dissolution aids, solubilizers, preservatives, etc. These substrates and additives may be used alone or in combination of two or more. The contents of these base materials and additives can be appropriately set depending on the formulation form, etc.

In addition to the above-mentioned components, the skin cleansing composition of the present invention may contain other pharmacological ingredients as necessary within the scope of the invention, so long as the effects of the present invention are not impaired. Examples of such pharmacological ingredients include vitamins (vitamin A, vitamin B1, vitamin B2, vitamin B5, vitamin B6, vitamin B12, vitamin C, vitamin D, vitamin K, niacin, folic acid, biotin, lycopene, etc.), antihistamines (diphenhydramine, diphenhydramine hydrochloride, etc.), local anesthetics (procaine, tetracaine, bupivacaine, mepivacaine, chloroprocaine, proparacaine, meprylcaine or salts thereof, orthocaine, oxethazaine, oxalate, etc.), and the like. Examples of such pharmacological ingredients include polyethylhexyl ether, scolymus extract, percaminpase, tesitdesitin, etc.), anti-inflammatory agents (indomethacin, felbinac, diclofenac sodium, loxoprofen sodium, etc.), skin protectants (collodion, castor oil, etc.), blood circulation promoters (nonyl acid vanillylamide, nicotinic acid benzyl ester, capsaicin, chili pepper extract, etc.), cooling agents (menthol, camphor, borneol, peppermint water, peppermint oil, etc.), mucopolysaccharides (sodium chondroitin sulfate, glucosamine, etc.). These pharmacological ingredients may be used alone or in combination of two or more. When these pharmacological ingredients are contained, the content may be appropriately set depending on the type of pharmacological ingredient used, the expected effect, etc.

Form The form of the skin cleanser composition of the present invention is not particularly limited, and examples thereof include liquid, cream, gel, etc., but is preferably a liquid or gel at room temperature. When the skin cleanser composition of the present invention is in a liquid or gel form, the viscosity at 20° C. is 10,000 mPa·s or less, preferably 5,000 mPa·s or less. The viscosity is a value measured with a BL viscometer (rotor No. 3, 6 rpm, 20° C.). The skin cleanser composition of the present invention may also be in a form in which a sheet substrate such as cotton or nonwoven fabric is impregnated with the liquid skin cleanser composition.

Container The container for housing the skin cleanser composition of the present invention is not particularly limited and may be appropriately selected depending on the form, use, etc., and examples thereof include a spray type container, a pour-down or drop-down type container (particularly a cleaning bottle), a pump type container, a tube type container, a packaging bag, a box-shaped container, etc. In particular, when the skin cleanser composition of the present invention is in a liquid form, the container is preferably a spray type container, a pour-down or drop-down type container (particularly a cleaning bottle), or a pump type container. Note that the pump type container in the present invention is a container that discharges the skin cleanser composition in a liquid state, and the spray type container is a container that discharges the contents in a mist state, and both are different from a pump foamer container that discharges the skin cleanser composition in a foam state. In addition, when the skin cleanser composition of the present invention is in a form impregnated into a sheet substrate, examples of the container include a packaging bag and a box-shaped container.

In the present invention, among these containers, spray containers are particularly preferred from the viewpoints of ease of application to the skin and avoidance of physical friction caused by the hands during application. Examples of spray containers include pump spray containers, which are non-aerosol spray containers, and aerosol spray containers. The aperture (inner diameter of the nozzle) of the spray container is, for example, 0.01 to 3 mmφ, preferably 0.1 to 1 mmφ. When the spray container is a pump spray container, the amount sprayed per push is, for example, 0.05 to 1.2 g, preferably 0.1 to 0.3 g.

Uses The skin cleansing composition of the present invention is used to remove body fluids such as oils and fats, sweat, and dirt from the skin, and is not used as a makeup remover (cleansing). The skin cleansing composition of the present invention is used by applying it directly to the skin without diluting it with water or foaming it. The amount of use per application varies depending on the concentration of the surfactant and the level of dirt, but for example, when used for face washing, it is 0.5 to 3 g, preferably 1 to 2 g.

As a specific mode of use, when the skin cleanser composition of the present invention is contained in a pour-on or drop-off container (particularly a cleaning bottle), a pump-type container, a tube-type container, or the like, the skin cleanser composition can be taken from the container and then applied to the area to be cleaned by hand. Also, when the skin cleanser composition of the present invention is impregnated into a sheet substrate, the sheet substrate can be taken in the hand and applied to the area to be cleaned.

As a particularly preferred mode of use, the skin cleanser composition contained in a spray container, pour-on or drop-on container (particularly a cleaning bottle), preferably a spray container, can be applied directly to the area to be cleaned without taking it in the hands. When the skin cleanser composition is applied directly to the area to be cleaned, cleaning is possible only by using the mechanical force of the liquid flow without any physical friction such as friction between the skin of the area to be cleaned and the hands, or between the skin of the area to be cleaned and air bubbles. Since the skin cleanser composition of the present invention is formulated to be low-irritating and has excellent cleaning power, cleaning using the mechanical force of the liquid flow without physical friction in this way significantly reduces the burden on the skin during cleaning, making it possible to perform an extremely gentle cleaning method. Note that the skin cleanser composition of the present invention is particularly suitable for cleaning methods that do not cause physical friction to the skin as described above, but does not exclude a method of use in which the skin cleanser composition is applied to the area to be cleaned and then scrubbed with hands, etc.

The areas to be cleaned with the skin cleanser composition of the present invention are not particularly limited, as any part of the body can be cleaned, and examples include hands, hair, scalp, body, and face. In particular, the skin cleanser composition of the present invention is suitable for use on the face, which is sensitive to irritation, as it is low-irritant and has excellent cleaning power.

After washing, the skin cleanser composition can be washed off with water. When washing off with water, it may be done in the same way as normal face washing, but from the viewpoint of reducing the burden on the skin, it is preferable to wash off using the mechanical force of a water flow without causing friction with the hands.

In addition, since the surfactant concentration of the skin cleanser composition of the present invention is extremely low, it does not need to be rinsed off after cleaning. Therefore, the skin cleanser composition of the present invention is also suitable for use in wiping in hospitals, for skin cleansing treatments such as face washing in beauty salons and hairdressing salons, and for use as disaster supplies. If it is not rinsed off, the skin cleanser composition remaining on the cleaned area may be removed by absorbing it using a water-absorbent substrate such as a towel or tissue.

Production Method The skin cleansing composition of the present invention is produced by mixing the aforementioned components (A) and (B) and other components that are blended as necessary, and preparing the mixture into a predetermined form.

2. Method for Improving Detergency As described above, the amphiphilic ester can improve the detergency of a skin cleansing composition containing 0.025 to 2 wt % of a surfactant while maintaining low irritation to the skin. Therefore, the present invention further provides a method for improving the detergency of a skin cleansing composition containing 0.025 to 2 wt % of a surfactant, which is component (A), by blending the skin cleansing composition with an amphiphilic ester, which is component (B), together with the component (A).

In the present invention, improving the cleaning power means that a skin cleansing composition containing 0.025 to 2% by weight of a surfactant exhibits superior cleaning power compared to a skin cleansing composition not containing an amphiphilic ester.

In the method for improving cleansing power, the types and amounts of ingredients used, the form of the skin cleansing composition, etc. are as shown in the section "1. Skin cleansing composition" above.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these.

Skin cleansing compositions were prepared having the compositions shown in Tables 1 to 4. Details of each component shown in Tables 1 to 4 are as follows. The skin cleansing compositions shown in Tables 1 to 4 were liquid, and had a viscosity at 20°C (measured with a BL viscometer (Brookfield B-type viscometer) rotor No. 3, 6 rpm) of 5000 mPa·s or less.
Sodium laurate (NONSAL LN-1 (product name) manufactured by NOF Corporation)
・ TEA-Cocoyl Glutamate ("Amisoft CT-12S (product name)" manufactured by Ajinomoto Co., Inc.)
- Sodium methyl cocoyl taurate ("Diapon K-SF (product name)" manufactured by NOF Corporation)
- Sodium N-lauroyl aspartate solution (20% by weight) ("Aminoformer FLDS-L (product name)" manufactured by Asahi Kasei Fine Chemical Co., Ltd.)
Polyoxyethylene lauryl ether acetic acid ("Kao Akipo RLM-45 (product name)" manufactured by Kao Corporation)
Cocamide DEA ("Amizol CDE-G (product name)" manufactured by Kawaken Fine Chemical Co., Ltd.)
PEG-60 hydrogenated castor oil (polyoxyethylene hydrogenated castor oil; "NIKKOL HCO-60 (product name)" manufactured by Nikko Chemicals Co., Ltd.)
- Polyoxyethylene sorbitan monostearate (Kao Corporation, Rheodor TW-S120V)
Glycerin mono-2-ethylhexyl ether (SEPPIC "Sensiva"
SC 50 JP (product name)
Cocamidopropyl betaine ("Softazoline CPB (product name)" manufactured by Kawaken Fine Chemicals Co., Ltd.)
Lauryl hydroxysulfobetaine solution (30% by weight) ("Amphitol 20HD (product name)" manufactured by Kao Corporation)
- Lysolecithin ("Lysolecithin Kyowa (product name)" manufactured by Kyowa Hakko Bio Co., Ltd.)
Quillaja extract ("Quillaja extract BG" manufactured by Maruzen Pharmaceutical Co., Ltd., saponin content 5% by weight)
Cyclohexane-1,4-dicarboxylate bisethoxydiglycol ("Neosolue-Aquilio (product name)" manufactured by Nippon Fine Chemicals Co., Ltd.)
Bisethoxydiglycol succinate ("High Aquostar DCS (product name)" manufactured by Kokyu Alcohol Kogyo Co., Ltd.)

<Cleaning power evaluation>
The prepared skin cleansing compositions were evaluated for cleansing power by 10 panelists specializing in cosmetic evaluation. Specifically, each skin cleansing composition was placed in a pump-type spray container ("Z-155-C110 (trade name)" manufactured by Takemoto Container Co., Ltd., spraying amount per push is 0.15 g), and 1.5 g was applied by spraying directly onto the face. The composition was left for about 5 seconds, and then washed off with water without touching the face with hands. After holding the face with a towel to absorb the water, the feeling of removing dirt from the skin was evaluated by sensory evaluation and scored based on the following index.

5 points: Dirt was thoroughly removed 4 points: Dirt was removed 3 points: Neither 2 points: Dirt was not removed very much 1 point: Dirt was not removed at all

The scores obtained by the 10 panelists were totaled and the degree of cleaning power was evaluated according to the following classification. The results are shown in Tables 1 to 4.
◎: 45 points or more
○: 40 points or more and less than 45 points
△: 35 points or more and less than 40 points
×: Less than 35 points

<Evaluation of Tightness (Sensory Evaluation of Skin Irritation)>
The prepared skin cleansing compositions were evaluated for their feeling of tightness by 10 panelists specializing in cosmetic evaluation. Specifically, each skin cleansing composition was placed in a pump-type spray container ("Z-155-C110 (product name)" manufactured by Takemoto Container Co., Ltd. (amount sprayed per push is 0.15 g) and 1.5 g was applied by spraying directly onto the face. The composition was left for about 5 seconds, and then the face was washed with water without touching the hands to the face. The face was held with a towel to absorb the water, and the feeling of tightness was evaluated by sensory evaluation and scored based on the following index.

5 points: no sense of tension at all 4 points: almost no sense of tension 3 points: only slight sense of tension 2 points: some sense of tension 1 point: strong sense of tension

The scores obtained by the 10 panelists were totaled, and the degree of tightness was evaluated according to the following classification. The results are shown in Tables 3 and 4.
◎: 45 points or more
○: 40 points or more and less than 45 points
△: 35 points or more and less than 40 points
×: Less than 35 points

<Cultured epidermis skin irritation test (in vitro evaluation of skin irritation)>
The prepared skin cleansing composition was subjected to a cultured epidermis skin irritation test as follows.
1. Preparation of cultured epidermis model LabCyte EPI-MODEL24 The assay medium was warmed and added to a 24-well assay plate in 0.5 mL portions. The cultured epidermis model LabCyte EPI-MODEL24 (lot number: LCE24-180226-A) was transferred to the 24-well assay plate to which the assay medium had been added. After confirming that there were no air bubbles on the bottom of the culture cup, the cup was placed in a _CO2 incubator and left to stand for at least 1 hour before exposure to the test substance.

2. Application of test substance and washing Of the 24 epidermal models, 12 were used (the remaining ones were kept in pre-culture until the main test). The 24-well assay plate was removed from the _CO2 incubator. The assay medium was warmed and added to the third row of the 24-well assay plate at 1.0 mL each. The test substance (each skin cleanser composition) was dropped at 25 μL onto the cultured epidermis in the culture cup without using a pump-type spray container, and was exposed to the whole surface. After 1 minute, 5 minutes, and 10 minutes of exposure, the test substance was removed by suction, and the cultured epidermis model in the cup was washed with phosphate buffer solution (PBS) and transferred to the third row of the 24-well assay plate.

3. MTT test The MTT test is a method for measuring cell viability by measuring the absorbance at 570 nm after MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] taken up into cells is reduced by mitochondrial dehydrogenase in the cells to produce a formazan dye, which is extracted with an organic solvent.

10 mL of MTT medium was prepared with a final concentration of 0.5 mg/mL. The MTT medium was warmed and added to the fourth row of a 24-well assay plate in 0.5 mL portions. The cultured epidermis model was transferred to the fourth row of a 24-well assay plate, placed in a CO2 incubator, and subjected to the MTT reaction for 3 hours. After the MTT reaction was completed, the cultured skin was picked up with tweezers and transferred to a 1.5 mL microtube. 300 μL of isopropanol was added to the microtube to completely immerse the cultured epidermis model. After that, the microtube was left to stand for 2 hours, and the microtube was vortexed to extract the pigment. The extract (200 mL) was added to each well of a 96-well plate. In addition, 200 μL of isopropanol was added to A1 as a blank (negative control). The absorbance at 570 nm and 650 nm was measured using a microplate reader. The absorbance at 650 nm was subtracted from the absorbance at 570 nm to obtain the measured value, and the viability of the test substance was calculated using the following formula.

The cell viability was classified according to the following criteria, and the skin irritation was evaluated. The results are shown in Tables 3 and 4.
◎: 90% or more
○: 75% or more but less than 90%
△: 65% or more and less than 75%
×: 50% or more but less than 65% ××: Less than 50%

As shown in Tables 1 to 4, skin cleansing compositions containing a surfactant at a concentration of more than 2% by weight (Comparative Examples 16 to 19) were found to be skin irritating, and skin cleansing compositions containing a surfactant at a concentration of 0.025 to 2% by weight (Comparative Examples 1 to 10) were found to have no cleansing power. In contrast, skin cleansing compositions containing an amphiphilic ester (Comparative Examples 11 to 15) that does not exhibit cleansing power alone together with 0.025 to 2% by weight of a surfactant (Examples 1 to 20) showed improved cleansing power. Moreover, as shown in Examples 9 to 20, the skin cleansing composition of the present invention was shown to have improved cleansing power while being low irritant.

Claims (3)

A skin cleansing composition which contains: (A) an anionic surfactant selected from the group consisting of laurate, cocoyl glutamate, cocoyl methyl taurate, and lauroyl aspartate; a nonionic surfactant selected from the group consisting of PEG-60 hydrogenated castor oil and cocamide diethanolamide, cocamidopropyl betaine , and / or a natural surfactant selected from the group consisting of lysolecithin and saponin ; (B) bis-ethoxydiglycol cyclohexane-1,4-dicarboxylate and/or bis-ethoxydiglycol succinate ; and water, wherein the content of component (A) is 0.025 to 2% by weight and the content of component (B) is 0.3% by weight or more, and the composition is not for use as a makeup remover. 2. The skin cleansing composition according to claim 1 , wherein the content of component (A) is 0.025 to 0.9% by weight. (A) A method for improving detergency in a skin cleanser composition not used as a makeup remover, the method comprising: (A) an anionic surfactant selected from the group consisting of laurate, cocoyl glutamate, cocoyl methyl taurate, and lauroyl aspartate; ( B) 0.025 to 2% by weight of a nonionic surfactant selected from the group consisting of PEG-60 hydrogenated castor oil and cocamide diethanolamide, cocamidopropyl betaine , and / or a natural surfactant selected from the group consisting of lysolecithin and saponin; and (C) water, the method comprising the steps of:
A method for improving detergency, comprising blending 0.3% by weight or more of (B) bisethoxydiglycol cyclohexane-1,4-dicarboxylate and/or bisethoxydiglycol succinate together with the component (A) in a skin cleansing composition.