Skin cleansing method

Abstract

To provide a skin cleansing method and a skin cleansing agent composition for selectively removing free unsaturated fatty acids in sebum on the skin.SOLUTION: Provided is a skin cleansing method for selectively removing free unsaturated fatty acids in sebum on the skin using a cleansing agent composition containing 0.5 mass% or more and 15 mass% or less of (A) an internal olefin sulfonate having 12 or more and 24 or less carbon atoms, wherein a residual ratio of the unsaturated fatty acids to sebum components other than the unsaturated fatty acids calculated by the following method is 0.5 or less. The method for calculating the remaining ratio of the unsaturated fatty acids to sebum components other than unsaturated fatty acids comprises: applying equal amounts of oleic acid as an unsaturated fatty acid and cottonseed oil as a sebum component other than unsaturated fatty acids onto an artificial skin model; and after massaging the test detergent composition with fingers to wash, rinsing with water and measuring remaining amounts of oleic acid and cottonseed oil using an oil content meter using a light transmission method, and calculating the remaining ratio of the unsaturated fatty acids by dividing the remaining amount of oleic acid by the remaining amount of cottonseed oil.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a skin cleansing method and a skin cleansing composition.

Background Art

[0002] In recent years, the number of people with various skin problems such as not only dryness but also itching, color unevenness, and acne on their bodies has been increasing, and milder skin cleansers for the skin are in demand. For this purpose, it is necessary to remove components that are irritating to the skin. Unsaturated fatty acids are particularly known as components that are irritating to the skin. This is a component generated by the decomposition of triglycerides contained in secreted sebum by resident bacteria.

[0003] In skin cleansers, cleansers that selectively remove specific lipid components have been reported. For example, cleansers that suppress the elution of intercellular lipids such as cholesterol and ceramide in the stratum corneum have been reported (Patent Documents 1 to 3). Also, in order to selectively remove squalene, which is an easily oxidizable sebum component on the skin, cleansers containing sodium ethyl ester sulfonate of palm oil fatty acid have been reported (Patent Document 4).

[0004] However, these skin cleansers do not remove free unsaturated fatty acids, which are the cause of the expression of inflammation, the decline of the skin barrier function, and the growth of acne bacteria and Malassezia bacteria among the components in sebum. As a skin cosmetic that selectively removes free fatty acids that cause acne, skin cosmetics containing a weak base such as sodium hydrogen carbonate as a main component and having a pH in the range of 8.5 to 9.5 have been reported (Patent Document 5).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0006] The cosmetic described in Patent Document 5 is weakly alkaline and has a low surfactant content, so there is a problem with foam performance when used as a body wash. An object of the present invention is to solve the above problems and provide a skin cleansing method and a skin cleansing agent composition that selectively remove free unsaturated fatty acids in sebum on the skin.

Means for Solving the Problems

[0007] Therefore, the present inventors performed a cleaning operation using an artificial skin model coated with oleic acid as a representative of free unsaturated fatty acids and cottonseed oil as a representative of other sebum components, triglyceride, and screened for a composition capable of selectively removing unsaturated fatty acids. As a result, a cleaning agent composition containing 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms was found to be a skin cleaning agent capable of making the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids 0.5 or less and selectively removing free unsaturated fatty acids in sebum on the skin, and the present invention was completed.

[0008] That is, the present invention provides a skin cleansing method for selectively removing free unsaturated fatty acids in sebum on the skin, using a cleansing agent composition containing 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms, and having a residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the following method of 0.5 or less. Method for calculating the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids: The same amount of oleic acid as the unsaturated fatty acid and cottonseed oil as the sebum component other than the unsaturated fatty acid are applied onto an artificial skin model. After massaging and washing with the test detergent composition using fingers, rinsing with water, and then measuring the residual amounts of oleic acid and cottonseed oil respectively with an oil meter using the light transmission method, the residual ratio of unsaturated fatty acids is calculated by dividing the residual amount of oleic acid by the residual amount of cottonseed oil.

[0009] Moreover, the present invention provides a skin cleansing agent composition that contains 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms, and selectively removes free unsaturated fatty acids in sebum on the skin, and has a residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the following method of 0.5 or less. Method for calculating the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids: The same amount of oleic acid as the unsaturated fatty acid and cottonseed oil as the sebum component other than the unsaturated fatty acid are applied onto an artificial skin model. After massaging and washing with the test detergent composition using fingers, rinsing with water, and then measuring the residual amounts of oleic acid and cottonseed oil respectively with an oil meter using the light transmission method, the residual ratio of unsaturated fatty acids is calculated by dividing the residual amount of oleic acid by the residual amount of cottonseed oil.

Advantages of the Invention

[0010] By using the skin cleansing method or skin cleansing agent composition of the present invention, free unsaturated fatty acids in sebum on the skin can be selectively removed, and various skin troubles can be prevented.

Modes for Carrying Out the Invention

[0011] In this specification, the terms used are, unless otherwise specified, used in the meanings commonly used in the art.

[0012] In this specification, "skin" refers to human skin, which is one of the human organs and refers to the layer covering the surface of the body. The skin to be cleaned in the present invention includes the skin of the face, hands, feet, scalp, and the whole body.

[0013] In this specification, sebum refers to a liquid containing lipid components secreted from sebaceous glands. Since a part of sebum is decomposed by skin resident bacteria after being secreted from sebaceous glands, the components of sebum present on the skin are triglycerides, fatty acids, wax esters, squalene, and the like. Sebum is one of the factors that suppress the transpiration of skin moisture and is responsible for the barrier function of the skin. Among these components, free unsaturated fatty acids are the cause of the expression of inflammation, the decline of the skin barrier function, and the growth of acne bacteria and Malassezia bacteria. Therefore, it is preferably removed by washing.

[0014] In this specification, free unsaturated fatty acids are fatty acids generated by the decomposition of triglycerides in sebum, and their main components are palmitoleic acid and oleic acid. As described above, these free unsaturated fatty acids are known to be the cause of the expression of inflammation, the decline of the skin barrier function, and the growth of acne bacteria and Malassezia bacteria.

[0015] In this specification, selectively removing free unsaturated fatty acids in sebum on the skin means that when sebum is washed, the residual ratio of free unsaturated fatty acids to sebum components other than free unsaturated fatty acids is 0.5 or less. Specifically, it can be determined that the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the following method is 0.5 or less. (Calculation method of the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids): The same amount of oleic acid as the unsaturated fatty acid and cottonseed oil as the sebum component other than the unsaturated fatty acid are applied onto an artificial skin model. After massaging and washing with the test detergent composition with fingers and then rinsing with water, the residual amounts of oleic acid and cottonseed oil are measured respectively with an oil meter using the light transmission method, and the residual ratio of unsaturated fatty acids is calculated by dividing the residual amount of oleic acid by the residual amount of cottonseed oil (hereinafter referred to as "Calculation Method A"). More specifically, in this method, an equal amount of oleic acid and cottonseed oil is applied onto an artificial skin model, a test cleaning solution is discharged from a foam discharge container, and the foam is massaged circularly with a finger five times each. After rinsing with water, the residual amounts of oleic acid and cottonseed oil are measured respectively using an oil content meter based on the light transmission method. The residual ratio of oleic acid can be calculated by dividing the residual amount of oleic acid by the residual amount of cottonseed oil. Residual ratio X of oleic acid OL = Residual amount R of oleic acid OL / Residual amount R of cottonseed oil CO

[0016] One aspect of the present invention is a skin cleaning method for selectively removing free unsaturated fatty acids in sebum on the skin, using a cleaning composition containing 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms, wherein the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the above calculation method A is 0.5 or less.

[0017] Another aspect of the present invention is a skin cleaning composition for selectively removing free unsaturated fatty acids in sebum on the skin, containing 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms, wherein the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the above calculation method A is 0.5 or less.

[0018] The skin cleaning composition used in the present invention contains (A) an internal olefin sulfonate having 12 to 24 carbon atoms. As shown in the following examples, the internal olefin sulfonate having 12 to 24 carbon atoms as component (A) is superior in the function of selectively removing free unsaturated fatty acids in sebum by the above method compared to other anionic surfactants, such as fatty acid salts, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, N-acyl amino acid salts, and the like. In the present invention, the internal olefin sulfonate is a sulfonate obtained by sulfonating, neutralizing, and hydrolyzing an internal olefin (an olefin having a double bond inside the olefin chain) as a raw material. Note that such an internal olefin has a broad meaning including a case where a so-called α-olefin in which the position of the double bond is at the 1-position of the carbon chain is contained in a trace amount. That is, when an internal olefin is sulfonated, β-sultone is quantitatively generated, and a part of the β-sultone is changed to γ-sultone and olefin sulfonic acid, and further these are converted to hydroxyalkane sulfonate and olefin sulfonate in the neutralization / hydrolysis step (for example, J. Am. Oil Chem. Soc. 69, 39 (1992)). Here, the hydroxy group of the obtained hydroxyalkane sulfonate is inside the alkane chain, and the double bond of the olefin sulfonate is inside the olefin chain. Further, the obtained product is mainly a mixture of these, and a part of it may contain a trace amount of a hydroxyalkane sulfonate having a hydroxy group at the end of the carbon chain or an olefin sulfonate having a double bond at the end of the carbon chain. In this specification, each of these products and their mixtures are collectively referred to as internal olefin sulfonate (component (A)). Further, the hydroxyalkane sulfonate is referred to as a hydroxy form of the internal olefin sulfonate (hereinafter, also referred to as HAS), and the olefin sulfonate is referred to as an olefin form of the internal olefin sulfonate (hereinafter, also referred to as IOS).

[0019] From the viewpoint of the selective removability of free unsaturated fatty acids, the number of carbon atoms of the internal olefin sulfonate of component (A) is preferably 12 or more and 24 or less, more preferably 14 or more and 20 or less, and even more preferably 16 or more and 18 or less. The hydroxy form and the olefin form having these various numbers of carbon atoms are derived from the internal olefin used as a raw material, and the hydroxy form and the olefin form having a number of carbon atoms other than the above may be contained.

[0020] From the viewpoint of the selective removal property of free unsaturated fatty acids, the total content of the internal olefin sulfonate having 16 carbon atoms and the internal olefin sulfonate having 18 carbon atoms in component (A) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, yet more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% by mass or more. The upper limit of the total content is 100% by mass.

[0021] As is apparent from the above production method, the sulfonic acid group of the internal olefin sulfonate of component (A) is present inside the carbon chain of the internal olefin sulfonate, that is, inside the olefin chain or the alkane chain, and in some cases, a small amount of those having a sulfonic acid group at the end of the carbon chain may also be contained. In the present invention, in component (A), it is preferable in terms of foaming property and selective removal property of free unsaturated fatty acids that the content of the internal olefin sulfonate in which the position of the sulfonic acid group is at the 2-position of carbon is low and the content of the internal olefin sulfonate present more internally is high. When component (A) contains an internal olefin sulfonate having 16 carbon atoms and an internal olefin sulfonate having 18 carbon atoms, it is more preferable that the content of the internal olefin sulfonate in which the position of the sulfonic acid group is at the 2-position of the carbon chain is lower for both the internal olefin sulfonate having 16 carbon atoms and the internal olefin sulfonate having 18 carbon atoms. In addition, from the viewpoints of foaming property, low-temperature stability, and selective removal property of free unsaturated fatty acids, the content of the olefin sulfonate in which the position of the sulfonic acid group is at the 1-position of the olefin chain or the alkane chain in component (A) is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, still more preferably 2.0% by mass or less, yet more preferably 1.5% by mass or less, still more preferably 1.0% by mass or less. The lower limit of the content is preferably 0.01% by mass or more from the viewpoints of reducing production costs and improving productivity. Examples of the salt of the internal olefin sulfonic acid of component (A) include alkali metal salts such as sodium salts and potassium salts, and ammonium salts.

[0022] From the viewpoints of foam thickness and whiteness, the content of component (A) in the skin cleansing composition of the present invention is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more. From the viewpoint of foaming, it is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less.

[0023] From the viewpoint of selective washing with free unsaturated fatty acids, any surfactant other than component (A) contained in the skin cleansing composition of the present invention may be used as long as it is used in ordinary skin cleansers. From the viewpoints of moisturizing feeling after washing, smoothness after rinsing, and non-roughness of the skin, the skin cleansing composition of the present invention preferably further contains at least one selected from (B) anionic surfactants other than (A), (C) nonionic surfactants, and (D) amphoteric surfactants as component (B). (B) As an anionic surfactant other than component (A), one or more selected from alkyl sulfates, polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates, alkyl sulfosuccinate salts, polyoxyalkylene alkyl sulfosuccinate salts, fatty acid salts, N-acyl amino acid salts, N-acyl taurine salts, acyl isethionate salts, etc. can be mentioned. Among these, from the viewpoints of the moisturizing feeling after washing, the smoothness after rinsing, and the non-stiffness of the skin, one or more selected from polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates, N-acyl amino acid salts, and N-acyl taurine salts are more preferable. Furthermore, polyoxyalkylene alkyl ether sulfates such as polyoxyethylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates such as polyoxyethylene alkyl ether carboxylates, N-acyl-glutamate salts, N-cocoyl glutamate salts and N-acyl amino acid salts such as alkyl sarcosinate salts, N-acyl taurine salts such as N-acyl methyl taurine salts are preferable, and ammonium polyoxyethylene (1)-(4) lauryl ether sulfate (ammonium lauryl sulfate-1, sodium lauryl sulfate-2, etc.), polyoxyethylene (2)-(5) lauryl ether carboxylate (laureth-6 carboxylate, laureth-4 carboxylate, etc.), N-acyl-glutamate salt, lauroyl sarcosinate salt, N-acyl methyl taurine salt are more preferable. From the viewpoint of the selective removal of free unsaturated fatty acids, the content of component (B) in the skin cleansing composition is preferably 0.05% by mass or more and 15% by mass or less, more preferably 0.05% by mass or more and 12% by mass or less, and even more preferably 0.05% by mass or more and 10% by mass or less.

[0024] (C) As nonionic surfactants, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and polyoxyethylene-added nonionic surfactants such as polyoxyalkylene (hydrogenated) castor oil; sucrose fatty acid esters, polyglycerin alkyl ethers, alkyl glyceryl ethers, polyglycerin fatty acid esters, alkyl glycosides, alkyl polyglycosides, polyhydric alcohol type nonionic surfactants such as sorbitan fatty acid esters; or fatty acid alkanolamides, etc. may be mentioned. Among these, from the viewpoints of moisturizing feeling after washing, smoothness after rinsing, and non-stiffness of the skin, one or more selected from polyoxyethylene-added nonionic surfactants, alkyl glyceryl ethers, alkyl polyglycosides, and fatty acid alkanolamides are more preferable, and polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene fatty acid esters, and polyoxyethylene-added nonionic surfactants such as polyoxyethylene alkyl ethers; alkyl glyceryl ethers such as 2-ethylhexyl glycerin and isodecyl glyceryl ether; alkyl polyglycosides such as alkyl (C10-16) polyglycoside; and fatty acid alkanolamides such as coconut oil fatty acid N-methyl ethanolamide are more preferable. From the viewpoint of selective removal of free unsaturated fatty acids, the content of the component (C) in the skin cleansing composition is preferably 0.01% by mass or more and 15% by mass or less, more preferably 0.05% by mass or more and 12% by mass or less, and still more preferably 0.05% by mass or more and 10% by mass or less.

[0025] (D) As amphoteric surfactants, betaine surfactants such as imidazoline-based betaines, alkyldimethylaminoacetic acid betaines, fatty acid amide propyl betaines, sulfobetaines, or amine oxide surfactants such as alkyldimethylamine oxides can be mentioned. Among these, from the viewpoints of the moisturizing feeling after washing, the smoothness after rinsing, and the non-stiffness of the skin, fatty acid amide propyl betaines, sulfobetaines, etc. are preferable, and specifically, lauramidopropyl betaine or lauryl hydroxysulfobetaine is more preferable. From the viewpoint of the selective removal property of free unsaturated fatty acids, the content of component (D) in the skin cleansing agent composition is preferably 0.01% by mass or more and 15% by mass or less, more preferably 0.05% by mass or more and 12% by mass or less, and still more preferably 0.05% by mass or more and 10% by mass or less.

[0026] From the viewpoint of the selective removal property of free unsaturated fatty acids, the mass ratio A / (A + B + C + D) of component (A) in the total surfactant amount (component (A) + component (B) + component (C) + component (D)) is preferably 0.05 or more, more preferably 0.08 or more, still more preferably 0.1 or more, and still more preferably 0.5 or more. Moreover, from the viewpoints of the elasticity of the foam, the moisturizing feeling after washing, the smoothness after rinsing, and the non-stiffness of the skin, the upper limit is preferably 1.0 or less, preferably 0.9 or less, and still more preferably 0.8 or less.

[0027] In addition to the above components, the skin cleansing composition of the present invention can use components commonly used in ordinary cleansing compositions. For example, surfactants other than the above; polyhydric alcohols; lower alcohols such as ethanol and isopropyl alcohol; aromatic alcohols such as benzyl alcohol and benzyloxyethanol; cellosolves such as ethyl cellosolve and butyl cellosolve; carbitols such as ethyl carbitol and butyl carbitol; moisturizing components such as sugars (derivatives), amino acids (derivatives), animal and plant (protein) derivatives, and animal and plant extracts; silicone derivatives such as polyoxyalkylene-modified silicones; inorganic or organic salts such as sodium sulfate, sodium carbonate, sodium hydrogen carbonate, potassium chloride, sodium chloride, and sodium citrate; pH adjusters such as acids and alkalis; anti-inflammatory agents such as glycyrrhetinic acid, glycyrrhizic acid, and their derivatives; bactericides such as isopropylmethylphenol; preservatives, sequestering agents, antioxidants, ultraviolet absorbers, cationic polymers, anionic polymers, nonionic polymers, amphoteric polymers, fragrances, thickeners, vitamins, natural pigments, coloring agents such as tar pigments, and the like can be mentioned. The polyhydric alcohol is not particularly limited as long as it is commonly used in ordinary skin cleansers. For example, dihydric alcohols such as ethylene glycol, diethylene glycol, hexylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, dipropylene glycol, polypropylene glycol, isoprene glycol, and 1,3-butylene glycol; trihydric or higher alcohols such as glycerin, diglycerin, triglycerin, tetraglycerin, hexaglycerin, decaglycerin, and trimethylpropanol; sugars or sugar alcohols such as erythritol, pentaerythritol, dipentaerythritol, glucose, mannose, galactose, sucrose, fructose, maltose, maltitol, xylitol, inositol, sorbitan, and sorbitol can be mentioned. The cationic polymer is not particularly limited as long as it is used in ordinary detergents. Examples include cationic starches, cationized celluloses, cationized guar gum derivatives, diallyl quaternary ammonium salt polymers such as dimethyldiallylammonium chloride homopolymer, diallyl quaternary ammonium salt - acrylamide copolymers such as dimethyldiallylammonium chloride - acrylamide copolymer, N - vinylpyrrolidone - N,N - dimethylaminoethyl methacrylate copolymer, quaternized polyvinylpyrrolidone derivatives such as imidazolinium chloride - vinylpyrrolidone copolymer, polyglycol polyamine condensates such as dimethyldiethyl sulfate of dimethylaminoethyl methacrylate - N,N - dimethylacrylamide - polyethylene glycol dimethacrylate, adipic acid - dimethylhydroxypropyl ethylene triamine copolymer, cationized dextran, dimethylacrylamide - dimethylaminoethyl methacrylate copolymer, polyethyleneimine copolymer, poly(dimethylmethylenepiperidinium chloride), and the like. The anionic polymer is not particularly limited as long as it is used in ordinary detergents. Examples include homopolymers or copolymers containing at least one component selected from the group consisting of hyaluronic acid, carboxyvinyl polymer, carboxymethyl cellulose, acrylic acid, methacrylic acid, styrene sulfonic acid, acryloyldimethyltaurine, acryloyldimethyltaurine ammonium, alginic acid, aspartic acid, chondroitin sulfate, polyglutamic acid, and their salts. The nonionic polymer is not particularly limited as long as it is used in ordinary detergents. For example, vinyl-based thickeners such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, cellulose-based thickeners such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, and hydrophobized hydroxypropyl methyl cellulose, guar gum, sclerotium gum, tamarind gum, xanthan gum, dextran, pectin, pullulan, gelatin, locust bean gum, carrageenan, agar, biosaccharide gum, bentonite, dextrin fatty acid ester, dimethyldistearylammonium hectorite, sodium alginate, propylene glycol alginate ester, polyethylene glycol, macrogol, hydrophobically modified polyether urethane, and the like can be mentioned.

[0028] From the viewpoint of selective detergency, the pH of the skin cleansing composition of the present invention is not limited. From the viewpoint of imparting mildness to the skin, the pH is preferably in the range of 3.0 to 9.5, more preferably 3.0 to 8.5, and still more preferably 3.0 to 7.0. In the present invention, the pH is determined by filling 100 mL of a liquid detergent composition (stock solution or a solution diluted 20-fold with ion-exchanged water) into a beaker, adjusting the temperature to 30°C in a constant temperature bath at 30°C, immersing a pH measurement electrode for 1 minute, and measuring.

[0029] The skin cleansing method and the skin cleansing composition of the present invention are a skin cleansing method for selectively removing free unsaturated fatty acids in sebum on the skin, and a skin cleansing composition for selectively removing free unsaturated fatty acids in sebum on the skin, respectively. Here, the selective removal of free unsaturated fatty acids in sebum on the skin means that, as described above, when the sebum is washed, the residual ratio of free unsaturated fatty acids to sebum components other than free unsaturated fatty acids is 0.5 or less. Specifically, it can be determined that the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the above calculation method A is 0.5 or less. More specifically, in this method, the same amount of oleic acid and cottonseed oil is applied to an artificial skin model, the test cleaning liquid is discharged from a foam discharge container, and the foam is massaged circularly with a finger five times each. After rinsing with water, the residual amounts of oleic acid and cottonseed oil are measured respectively with an oil content meter using the light transmission method. The residual ratio of oleic acid can be determined by dividing the residual amount of oleic acid by the residual amount of triglyceride.

[0030] From the viewpoint of the selective removability of free unsaturated fatty acids, the skin cleaning method using the skin cleaning agent composition in the present invention is preferably a method of applying the cleaning agent composition in a liquid state to the skin to clean the skin, or a method of discharging the cleaning agent composition as foam and cleaning the skin with the discharged foam. The form of the skin cleaning agent composition in the present invention, the skin cleaning method using the skin cleaning agent composition, and the tool for cleaning the skin may be any as long as they are those used for general skin cleaning agents. However, the skin cleaning agent composition of the present invention is preferably a liquid composition, which is in a form of being applied to the skin in a liquid state, or a cleaning agent composition that is a liquid composition filled in a foam discharge container and discharged as foam.

[0031] The skin cleaning agent composition of the present invention can be produced by mixing the above components according to a conventional method to form a liquid composition and filling it into a container that can be discharged in a liquid state or a pump foamer container.

[0032] The skin to be cleaned by the skin cleaning agent composition of the present invention is the skin of the face, hands, feet, scalp, whole body, etc.

[0033] Regarding the above embodiments, the present invention further discloses the following embodiments. <1>A skin cleansing method for selectively removing free unsaturated fatty acids in sebum on the skin, using a detergent composition containing 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms, wherein the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the calculation method A is 0.5 or less. <2>The skin cleansing method according to <1>, wherein the component (A) is an internal olefin sulfonate having 16 to 18 carbon atoms. <3>In the component (A), the total content of the internal olefin sulfonate having 16 carbon atoms and the internal olefin sulfonate having 18 carbon atoms is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and even more preferably 95% by mass or more. The skin cleansing method according to <2>. <4>The content of the component (A) in the skin cleansing agent is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more, preferably 15% by mass or less, more preferably 12% by mass or less, and still more preferably 10% by mass or less. The skin cleansing method according to any one of <1> to <3>. <5>The skin cleansing method according to any one of <1> to <4>, wherein the detergent composition further contains at least one selected from (B) an anionic surfactant other than (A), (C) a nonionic surfactant, and (D) an amphoteric surfactant. <6>The mass ratio A / (A + B + C + D) of the component (A) in the total surfactant amount (component (A) + component (B) + component (C) + component (D)) is preferably 0.05 or more, more preferably 0.08 or more, still more preferably 0.1 or more, even more preferably 0.5 or more, and the upper limit is preferably 1.0 or less, preferably 0.9 or less, and more preferably 0.8 or less. The skin cleansing method according to <5>. <7>As component (B), one or more selected from polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates, N-acyl amino acid salts, and N-acyl taurine salts; as component (C), one or more selected from polyoxyethylene addition type nonionic surfactants, alkyl glyceryl ethers, alkyl polyglucosides, and alkanolamides; or as component (D), one or more selected from amidopropyl betaine and sulfobetaine. The skin cleansing method according to <5> or <6>. <8>The pH of the skin cleansing composition is preferably 3.0 to 9.5, more preferably 3.0 to 8.5, and still more preferably 3.0 to 7.0. The skin cleansing method according to any one of <1> to <7>. <9>The skin cleansing method using the cleansing composition is a method of applying the cleansing composition in a liquid state to the skin to cleanse the skin, or a method of discharging the cleansing composition as foam and cleansing the skin with the discharged foam. The skin cleansing method according to any one of <1> to <8>. <10>The skin cleansing method using the cleansing composition is a method of discharging the cleansing composition as foam and cleansing the skin with the discharged foam. The skin cleansing method according to any one of <1> to <8>. <11>The cleansing composition is a cleansing composition filled in a pump foamer and discharged as foam. The skin cleansing method according to <10>.

[0034] <12>A skin cleansing composition that contains 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms and selectively removes free unsaturated fatty acids in sebum on the skin, and has a residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the calculation method A of 0.5 or less. <13>The component (A) is an internal olefin sulfonate having 16 to 18 carbon atoms. The skin cleansing composition according to <12>. <14>The total content of the internal olefin sulfonate with 16 carbon atoms and the internal olefin sulfonate with 18 carbon atoms in the component (A) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% by mass or more, which is the skin cleansing composition described in <13>. <15>The content of the component (A) in the skin cleansing composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more, preferably 15% by mass or less, more preferably 12% by mass or less, and still more preferably 10% by mass or less, which is the skin cleansing composition described in any one of <12> to <14>. <16>The skin cleansing composition described in any one of <12> to <15> further contains at least one selected from (B) an anionic surfactant other than the component (A), (C) a nonionic surfactant, and (D) an amphoteric surfactant. <17>The mass ratio A / (A + B + C + D) of the component (A) in the total surfactant amount (component (A) + component (B) + component (C) + component (D)) is preferably 0.05 or more, more preferably 0.08 or more, still more preferably 0.1 or more, even more preferably 0.5 or more, and the upper limit is preferably 1.0 or less, preferably 0.9 or less, and still more preferably 0.8 or less, which is the skin cleansing composition described in <16>. <18>The skin cleansing composition described in <16> or <17> contains at least one selected from polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates, N-acyl amino acid salts, and N-acyl taurine salts as the component (B), at least one selected from polyoxyethylene-added nonionic surfactants, alkyl glyceryl ethers, alkyl polyglucosides, and alkanolamides as the component (C), or at least one selected from amidopropyl betaine and sulfobetaine as the component (D). <19>The pH of the skin cleansing composition is preferably 3.0 to 9.5, more preferably 3.0 to 8.5, and still more preferably 3.0 to 7.0, which is the skin cleansing composition described in any one of <12> to <18>. <20>The skin cleansing composition is the skin cleansing composition used in the method of applying the skin cleansing composition in a liquid state to the skin to cleanse the skin, or the skin cleansing composition used in the method of discharging the skin cleansing composition as foam and cleansing the skin with the discharged foam, which is the skin cleansing composition according to any one of <12> to <19>. <21>The skin cleansing composition is the skin cleansing composition according to any one of <12> to <19>, which is used in the method of discharging the skin cleansing composition as foam and cleansing the skin with the discharged foam. <22>The skin cleansing composition is the skin cleansing composition according to <21>, which is filled in a pump foamer and discharged as foam.

Examples

[0035] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0036] Examples and Comparative Examples The components having the compositions shown in Tables 1 to 5 were mixed and filled into a pump foamer container (manufactured by Yoshino Kogyosha) equipped with three meshes (#200, #305, #90) and having a volume ratio (air / composition) in the gas-liquid mixing section of 20 / 1 to produce a skin cleansing composition. Oleic acid and cottonseed oil were applied in the same amount to Bioskin (manufactured by View Rakus) as an artificial skin model. The test cleaning liquid was discharged once with a pump foamer, and the foam was massaged circularly with fingers five times each. The massage was performed with a pressure on the Bioskin of 2.5 kgf / cm 2 as follows. Here, the pressure on the Bioskin can be calculated by measuring the gravity applied to the Bioskin with an electronic balance. After rinsing with water at 40°C, the residual amounts of oleic acid and cottonseed oil were measured using a sebum meter (manufactured by Courage&Khazaka), respectively. The residual ratio of unsaturated fatty acids was calculated by dividing the residual amount of oleic acid by the residual amount of cottonseed oil. The obtained residual ratios of unsaturated fatty acids to sebum components other than unsaturated fatty acids are shown in Tables 1 to 5. The values described in the tables indicate the values as the active ingredients.

[0037]

Table 1

[0038]

Table 2

[0039]

Table 3

[0040]

Table 4

[0041]

Table 5

[0042] As shown in Tables 1 to 5, when the sebum on the skin is washed using the skin cleansing agent composition of the present invention, the free unsaturated fatty acids in the sebum on the skin can be selectively removed.

Claims

1. A skin cleansing method for selectively removing free unsaturated fatty acids in sebum on the skin, which uses a cleansing composition containing 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms, and in which the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the following method is 0.5 or less. Calculation method for the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids: The same amount of oleic acid as the unsaturated fatty acid and cottonseed oil as the sebum component other than the unsaturated fatty acid are applied onto an artificial skin model. After massaging and washing with the test cleansing composition using a finger, rinsing with water, and then measuring the remaining amounts of oleic acid and cottonseed oil respectively with an oil meter using the light transmission method, the residual ratio of unsaturated fatty acids is calculated by dividing the remaining amount of oleic acid by the remaining amount of cottonseed oil.

2. The skin cleansing method according to claim 1, wherein the cleansing composition further contains at least one selected from (B) anionic surfactants other than (A), (C) nonionic surfactants, and (D) amphoteric surfactants as component (B).

3. The skin cleansing method according to claim 2, wherein the mass ratio A / (A + B + C + D) of component (A) in the total surfactant amount (component (A) + component (B) + component (C) + component (D)) is 0.05 or more.

4. The skin cleansing method according to claim 2 or 3, which contains at least one selected from polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates, N-acyl amino acid salts, and N-acyl taurine salts as component (B), at least one selected from polyoxyethylene-added nonionic surfactants, alkyl glyceryl ethers, alkyl polyglucosides, and alkanolamides as component (C), or at least one selected from amidopropyl betaine and sulfobetaine as component (D).

5. The skin cleansing method according to any one of claims 1 to 4, wherein the skin cleansing method using the cleansing composition is a method of discharging the cleansing composition as foam and washing the skin with the discharged foam.

6. The skin cleansing method according to claim 5, wherein the cleansing composition is a cleansing composition filled in a pump foamer and discharged as foam.

7. A skin cleansing composition that contains 0.5% by mass or more and 15% by mass or less of an internal olefin sulfonate having 12 to 24 carbon atoms and selectively removes free unsaturated fatty acids in sebum on the skin, and has a residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids calculated by the following method of 0.5 or less. Method for calculating the residual ratio of unsaturated fatty acids to sebum components other than unsaturated fatty acids: The same amount of oleic acid as an unsaturated fatty acid and cottonseed oil as a sebum component other than unsaturated fatty acids are applied onto an artificial skin model. After massaging and washing with the test cleansing composition with a finger, rinsing with water, and measuring the residual amounts of oleic acid and cottonseed oil respectively with an oil meter using the light transmission method, the residual ratio of unsaturated fatty acids is calculated by dividing the residual amount of oleic acid by the residual amount of cottonseed oil.

8. The skin cleansing composition according to claim 7, further containing at least one selected from (B) anionic surfactants other than component (A), (C) nonionic surfactants, and (D) amphoteric surfactants.

9. The skin cleansing composition according to claim 8, wherein the mass ratio A / (A + B + C + D) of component (A) in the total surfactant amount (component (A) + component (B) + component (C) + component (D)) is 0.05 or more.

10. The skin cleansing composition according to claim 9, containing at least one selected from polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates, N-acyl amino acid salts, and N-acyl taurine salts as component (B), at least one selected from polyoxyethylene addition type nonionic surfactants, alkyl glyceryl ethers, alkyl polyglucosides, and alkanolamides as component (C), or at least one selected from amidopropyl betaine and sulfobetaine as component (D).

11. The skin cleansing composition according to any one of claims 7 to 10, which is used in a method of discharging the skin cleansing composition as foam and washing the skin with the discharged foam.

12. The skin cleansing composition according to claim 11, which is filled in a pump foamer and discharged as foam.

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