Topical skin composition and stabilization method therefor

Abstract

To provide a topical skin composition comprising hydroxy fatty acids such as 4-hydroxyundecanoic acid, which enables suppression of cyclization of the hydroxy fatty acid in a formulation and prevents fragrance release prior to application to a skin, thereby enhancing stability.SOLUTION: There is provided a topical skin composition comprising: (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxyl group at a 4- or 5-position; (B) a fatty acid or a salt thereof; and (C) a neutralizing agent, wherein a neutralization ratio of the fatty acid is 70% to 120%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composition for external use on the skin and a method for stabilizing the same. [Background technology]

[0002] In recent years, people, regardless of gender, have become increasingly interested in odor etiquette. Research into various body odors has been conducted in earnest, and the main causes of odors such as sweat odor, armpit odor, foot odor, and aging odor have been identified. As countermeasures against such body odors, methods of masking with perfumes or cosmetics containing aromatic components, a method utilizing the odor-absorbing effect of charcoal (Patent Document 1), a method using an extract from the roots and rhizomes of Sanguinea japonica (Patent Document 2), a method using condensed persimmon tannin (Patent Document 3), and the like have been proposed. Furthermore, a technology for rejuvenating body odor using lactone, a component characteristic of the body odor of young women, is also known (Patent Document 4).

[0003] In perfumes, cosmetics and other fragrance products, the long-lasting fragrance during use is an important factor in bringing about a sense of satisfaction, a refreshing feeling, and a sense of elation to consumers, and in increasing the value of the product. Therefore, there is a strong demand for products that improve the persistence of fragrance after application. To meet such demands, sustained-release fragrance compositions that use hydroxy fatty acids, their derivatives, mixtures of dibasic acids and ethylene glycol or propylene glycol, etc., are known. When this sustained-release fragrance composition is applied to the skin, it gradually produces lactones, cyclic diesters, etc. over time by lipases in the skin tissue of the human body and lipases generated by skin resident bacteria, etc., and therefore it is possible to obtain a fragrance with extremely excellent persistence and fragrance quality (Patent Document 5). However, technical development of such products from the viewpoint of the stability of the ingredients is not currently progressing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-145747 A [Patent Document 2] JP 2011-183019 A [Patent Document 3] JP 2001-302483 A [Patent Document 4] International Publication No. 2019 / 059023 [Patent Document 5] JP 2003-313580 A Summary of the Invention [Problem to be solved by the invention]

[0005] Under such circumstances, the present inventors have been conducting research and development of a skin topical composition containing a hydroxy fatty acid such as 4-hydroxyundecanoic acid, and have encountered the problem that, depending on the composition, the hydroxy fatty acid may be cyclized in the formulation, releasing an aroma before application to the skin. It is known that hydroxy fatty acids and their salts are cyclized by lipases on the skin under heat or acidic conditions. This hydroxy fatty acid itself is unscented, but it is cyclized to become γ-undecalactone or the like, thereby releasing an aroma. Due to this function, it is thought that the hydroxy fatty acid or the like gradually causes the above reaction on the skin, thereby releasing an aroma for a long period of time, so it is inconvenient to release an aroma before application to the skin. Therefore, the present invention aims to provide a skin topical composition containing a hydroxy fatty acid such as 4-hydroxyundecanoic acid, in which the hydroxy fatty acid is not cyclized in the formulation, releasing an aroma before application to the skin. [Means for solving the problem]

[0006] In the course of intensive research to solve the above problems, the present inventors have noticed that in preparations containing fatty acids, even under alkaline conditions, hydroxy fatty acids undergo cyclization in the preparation, releasing fragrance before application to the skin. As a result of further research, they have found that if the neutralization rate of fatty acids is below a certain level, hydroxy fatty acids undergo cyclization in the preparation and cannot be stably blended, and that setting the neutralization rate of fatty acids to an appropriate level leads to stabilization of the preparation, thus completing the present invention. That is, the gist of the present invention is as follows.

[0007] [1] (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4th or 5th position; (B) a fatty acid or a salt thereof, and (C) Neutralizing agent A composition for external use on the skin, comprising the above-mentioned formula (I) and having a neutralization rate of fatty acids of 70% to 120%. [2] The topical skin composition described in [1], wherein component (A) contains 4-hydroxyundecanoic acid or a salt thereof. [3] The composition for external use on the skin according to [1] or [2], wherein component (B) contains a fatty acid having 12 to 22 carbon atoms or a salt thereof. [4] (C) The topical skin composition described in [1] or [2], wherein the neutralizing agent comprises potassium hydroxide and / or sodium hydroxide. [5] (A) A composition for external use on the skin containing a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4- or 5-position, (B) a fatty acid or a salt thereof, and (C) Neutralizing agent Combined with Adjusting the neutralization rate of fatty acids to 70% to 120%. A method for stabilizing (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4- or 5-position in the above composition. [6] The stabilization method described in [5], wherein the component (A) contains 4-hydroxyundecanoic acid or a salt thereof. [7] The method for stabilization according to [5] or [6], wherein the component (B) contains a fatty acid having 12 to 22 carbon atoms or a salt thereof. [8] (C) The stabilization method described in [5] or [6], wherein the neutralizing agent comprises potassium hydroxide and / or sodium hydroxide. Effect of the Invention

[0008] According to the present invention, in a composition for external use on the skin containing a hydroxy fatty acid such as 4-hydroxyundecanoic acid, it is possible to provide a preparation having excellent stability by suppressing the release of fragrance within the preparation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will now be described in detail. In addition, the terms used in this specification are to be interpreted as having the meanings usually used in the technical field unless otherwise specified.

[0010] [Skin external composition] The skin topical composition of the present invention contains (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4th or 5th position (hereinafter also referred to as "(A) component"), (B) a fatty acid or a salt thereof (hereinafter also referred to as "(B) component"), and (C) a neutralizing agent (hereinafter also referred to as "(C) component"), and is characterized in that the neutralization rate of the fatty acid is 70% to 120%. The skin topical composition of the present invention has the above composition, and is excellent in stability because it can suppress the cyclization of hydroxy fatty acids and the like in the preparation and release of a scent. Since the skin topical composition of the present invention is excellent in scent after application to the skin because the hydroxy fatty acids and the like are cyclized and release a scent after application to the skin, it can maintain the scent for a long time. The skin topical composition of the present invention may contain (D) a polyhydric alcohol and other optional components as other components in a range that does not impair the effects of the present invention, in addition to the essential components (A), (B) and (C). Each of these will be described in detail below.

[0011] <Component (A)> The topical skin composition of the present invention contains (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4th or 5th position. The hydroxy fatty acid of the present invention is a straight-chain hydrocarbon having 10 or more carbon atoms and a carboxyl group and a hydroxy group at the 4th or 5th position, and is a compound that becomes aromatic when cyclized by heat, acidic conditions, lipase, or the like. The hydroxy fatty acid of the present invention may have an unsaturated bond, and may be bonded with a substituent such as a methyl group.

[0012] The hydroxy fatty acid of the present invention preferably has a carbon number of 10 to 15, more preferably 10 to 13, and even more preferably 10 to 11. The carbon chain of the hydroxy fatty acid is preferably linear. Examples include 4-hydroxydecanoic acid, 4-hydroxyundecanoic acid, 4-hydroxydodecanoic acid, 4-hydroxytridecanoic acid, 4-hydroxytetradecanoic acid, 4-hydroxypentadecanoic acid, 4-hydroxyhexadecanoic acid, 5-hydroxydecanoic acid, 5-hydroxyundecanoic acid, 5-hydroxydodecanoic acid, 5-hydroxytridecanoic acid, 5-hydroxytetradecanoic acid, 5-hydroxypentadecanoic acid, and 5-hydroxyhexadecanoic acid. Among these, from the viewpoint of excellent aromatic properties after cyclization, those having a hydroxy group at the 4-position are preferred, and 4-hydroxydecanoic acid, 4-hydroxyundecanoic acid, and 4-hydroxydodecanoic acid are more preferred, and 4-hydroxyundecanoic acid is even more preferred.

[0013] Examples of the salts of hydroxy fatty acids in the present invention include alkali metal salts and alkaline earth metal salts of the above-mentioned hydroxy fatty acids. Examples of the alkali metal salts include sodium salts and potassium salts. Examples of the alkaline earth metal salts include magnesium salts and calcium salts. Among these, alkali metal salts of hydroxy fatty acids are preferred, and sodium salts of hydroxy fatty acids are more preferred. Specifically, sodium 4-hydroxydecanoate, sodium 4-hydroxyundecanoate, sodium 4-hydroxydodecanoate, sodium 4-hydroxytridecanoate, sodium 4-hydroxytetradecanoate, sodium 4-hydroxypentadecanoate, sodium 4-hydroxyhexadecanoate, sodium 5-hydroxydecanoate, sodium 5-hydroxyundecanoate, sodium 5-hydroxydodecanoate, sodium 5-hydroxytridecanoate, sodium 5-hydroxytetradecanoate, sodium 5-hydroxypentadecanoate, sodium 5-hydroxyhexadecanoate, potassium 4-hydroxydecanoate, potassium 4-hydroxyundecanoate, 4-hydroxypentadecanoate, potassium 5-hydroxyhexadecanoate, potassium 4-hydroxydecanoate, potassium 4-hydroxyundecanoate, potassium 4-hydroxypentadecano ... Examples of the hydroxypropyl 5-hydroxypropyl ester include potassium 4-hydroxydodecanoate, potassium 4-hydroxytridecanoate, potassium 4-hydroxytetradecanoate, potassium 4-hydroxypentadecanoate, potassium 4-hydroxyhexadecanoate, potassium 5-hydroxydecanoate, potassium 5-hydroxyundecanoate, potassium 5-hydroxydodecanoate, potassium 5-hydroxytridecanoate, potassium 5-hydroxytetradecanoate, potassium 5-hydroxypentadecanoate, and potassium 5-hydroxyhexadecanoate. Of these, sodium 4-hydroxydecanoate, sodium 4-hydroxyundecanoate, and sodium 4-hydroxydodecanoate are preferred, and sodium 4-hydroxyundecanoate is more preferred.

[0014] As the component (A) contained in the topical skin composition of the present invention, any of the above-mentioned hydroxy fatty acids and their salts are sufficiently effective, but from the viewpoint of stability in the formulation, the above-mentioned salts of hydroxy fatty acids are preferred.

[0015] Examples of lactones that may be produced on the skin when the topical skin composition of the present invention is applied to the skin include γ-lactones such as γ-decalactone, γ-undecalactone, and γ-dodecalactone, and δ-lactones such as δ-decalactone, δ-undecalactone, and δ-dodecalactone.

[0016] The content of the (A) component in the skin topical composition of the present invention is 0.00001% by weight to 10% by weight, and from the viewpoint of the fragrance after application to the skin, it is preferably 0.00005% by weight to 8% by weight, more preferably 0.0001% by weight to 5% by weight, even more preferably 0.0005% by weight to 3% by weight, particularly preferably 0.001% by weight to 2% by weight, and even more particularly preferably 0.01% by weight to 1% by weight. When two or more compounds are used in combination as the (A) component, the total amount of the compounds may be within the above numerical range.

[0017] <(B) component> The composition for external use on skin of the present invention contains (B) a fatty acid or a salt thereof. The fatty acid in the present invention refers to a component that is composed of a hydrocarbon group and a carboxyl group and does not have a hydroxyl group (excluding -OH of the carboxy group). As the fatty acid in the present invention, one having about 8 to 26 carbon atoms, preferably about 8 to 22 carbon atoms, more preferably about 12 to 22 carbon atoms, is usually used. The fatty acid may be a straight-chain fatty acid or a branched-chain fatty acid, and may be a saturated fatty acid or an unsaturated fatty acid. A straight-chain fatty acid or a saturated fatty acid is preferable, and a straight-chain saturated fatty acid is more preferable.

[0018] The fatty acid in component (B) is not particularly limited, but examples thereof include linear saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, and behenic acid; unsaturated fatty acids such as undecylic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, paccenic acid, elaidic acid, ricinoleic acid, petroselinic acid, arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid; branched fatty acids such as isopalmitic acid and isostearic acid; and mixed fatty acids such as coconut oil fatty acid, beef tallow fatty acid, and palm kernel oil fatty acid. Among these, preferred are straight-chain fatty acids having 12 to 22 carbon atoms, such as lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, and behenic acid; unsaturated fatty acids, such as oleic acid, linoleic acid, and linoleic acid; branched fatty acid, such as isostearic acid; and mixed fatty acids, such as coconut oil fatty acid, beef tallow fatty acid, and palm kernel oil fatty acid. From the viewpoint of the effects of the invention, more preferred are lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, coconut oil fatty acid, beef tallow fatty acid, and palm kernel oil fatty acid, and particularly preferred are lauric acid, myristic acid, and palmitic acid. These can be used alone or in combination of two or more. From the viewpoint of the effects of the invention, it is preferable to use two or more in combination, and it is more preferable to use three or more in combination.

[0019] Examples of fatty acid salts in component (B) include, but are not limited to, metal salts such as potassium salts, lithium salts, and sodium salts; ammonium salts such as ammonium salts and alkylammonium salts; and amine salts such as monoethanolamine salts, diethanolamine salts, triethanolamine salts, aminomethylpropanol salts, and tromethamine salts.

[0020] The content of component (B) in the topical composition for skin of the present invention is 0.1% by weight to 60% by weight, and from the viewpoint of the fragrance after application to the skin, it is preferably 0.5% by weight to 55% by weight, more preferably 1% by weight to 50% by weight, even more preferably 5% by weight to 45% by weight, particularly preferably 7% by weight to 42% by weight, and more particularly preferably 10% by weight to 40% by weight.

[0021] The ratio of the content (wt%) of component (B) to the content (wt%) of component (A) in the topical skin composition of the present invention (the value obtained by dividing the content (wt%) of component (B) by the content (wt%) of component (A)) is preferably 10 to 4,000, more preferably 50 to 3,000, even more preferably 100 to 2,000, and particularly preferably 150 to 1,500.

[0022] <(C) component> The skin external composition of the present invention contains a neutralizing agent (C) for the purpose of adjusting the neutralization rate of fatty acids to a preferred range such as 70% to 120%. Examples of the neutralizing agent in the present invention include inorganic alkaline compounds, organic amine compounds, and basic amino acids. Specifically, inorganic alkaline compounds such as sodium hydroxide and potassium hydroxide; organic amine compounds such as (mono-, di-, and tri-)ethanolamine, (mono-, di-, and tri-)isopropanolamine, 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3-propanediol, and 2-amino-2-hydroxymethyl-1,3-propanediol; and basic amino acids such as arginine, lysine, and histidine. Among these, inorganic alkaline compounds are preferred, sodium hydroxide, triethanolamine, and potassium hydroxide are more preferred, potassium hydroxide and sodium hydroxide are even more preferred, and potassium hydroxide is particularly preferred. These may be used alone or in combination of two or more kinds.

[0023] The content of the (C) component in the skin topical composition of the present invention is 0% by weight to 20% by weight, and from the viewpoint of the fragrance after application to the skin, it is preferably 0.1% by weight to 15% by weight, more preferably 0.5% by weight to 10% by weight, even more preferably 1% by weight to 10% by weight, and particularly preferably 2% by weight to 8% by weight. The content of the (C) component is adjusted so that the neutralization rate of the fatty acid contained in the skin topical composition of the present invention is 70% to 120%, and the neutralization rate is preferably 75% to 120%, more preferably 75% to 115%, even more preferably 75% to 110%, even more preferably 80% to 110%, and particularly preferably 80% to 100%. In the skin topical composition of the present invention, by adjusting the neutralization rate of the fatty acid to be within the above range, the (A) component becomes stable in the formulation, and it is less likely to cyclize and release a fragrance before application to the skin. In the skin topical composition of the present invention, the neutralization rate (%) is calculated from the amount of each component to be blended, as shown in the examples. When a fatty acid and / or fatty acid salt as component (B) and a neutralizing agent as component (C) are blended, the neutralization rate (%) is calculated by multiplying the amount (mol) of the neutralizing agent by the valence of the base and the amount (mol) of the blended fatty acid salt (already neutralized), dividing the sum by the total amount (mol) of the blended fatty acid and fatty acid salt, and then multiplying the result by 100. Neutralization rate (%) = [{amount of neutralizing agent (mol) × valence + amount of fatty acid salt (mol)} / total amount of fatty acid and fatty acid salt (mol)}] × 100

[0024] The ratio of the content (wt%) of component (C) to the content (wt%) of component (A) in the topical skin composition of the present invention (the value obtained by dividing the content (wt%) of component (C) by the content (wt%) of component (A)) is preferably 0.1 to 3,000, more preferably 0.5 to 2,000, even more preferably 1 to 1,500, even more preferably 5 to 1,000, and particularly preferably 10 to 500.

[0025] <(D) component> The skin topical composition of the present invention preferably further contains (D) a polyhydric alcohol. Examples of the polyhydric alcohol include glycerin, propylene glycol, butylene glycol, propanediol, dipropylene glycol, polyethylene glycol, diglycerin, sorbitol, pentanediol, and hexanediol. These may be used alone or in combination of two or more. In addition, from the viewpoint of achieving the effects of the invention, the polyhydric alcohol contained in the skin topical composition of the present invention is particularly preferably glycerin, propylene glycol, or butylene glycol.

[0026] The content of the polyhydric alcohol (D) in the composition for external use on skin of the present invention is usually 5% by weight to 50% by weight, preferably 8% by weight to 30% by weight, and more preferably 10% by weight to 20% by weight.

[0027] The content of the component (D) in the external skin composition of the present invention per part by weight of the component (A) is usually 1 to 400,000 parts by weight, preferably 5 to 300,000 parts by weight, and more preferably 10 to 200,000 parts by weight.

[0028] <Optional ingredients> In addition to the above-mentioned components, the composition for external use on the skin of the present invention may contain the following optional components within the scope that does not impair the effects of the present invention.

[0029] The skin topical composition of the present invention may contain, as optional components, for example, anti-inflammatory agents, refreshing agents, germicides, preservatives, vitamins, organic acids, moisturizing components, scrubbing agents, UV-absorbing components, UV-scattering components, astringent components, peptides or derivatives thereof, amino acids or derivatives thereof, cleansing components, keratin softening components, cell activating components, anti-aging components, blood circulation promoting components, whitening components, powders, etc. In the skin topical composition of the present invention, each of these components may be used alone or in combination of two or more types.

[0030] Examples of anti-inflammatory agents include allantoin and its derivatives, glycyrrhetinic acid and its derivatives, glycyrrhizic acid and its derivatives, salicylic acid derivatives, aminocaproic acid, azulene and its derivatives, zinc oxide, tocopherol acetate, hydrocortisone, prednisolone, and salts thereof.Specific examples include allantoin, allantoin chlorhydroxyaluminum, allantoin dihydroxyaluminum, glycyrrhetinic acid, glycyrrhetinic acid, stearyl glycyrrhetinate, glycol salicylate, methyl salicylate, epsilon aminocaproic acid, azulene, guaiazulene, and salts thereof.Note that the term "derivative" refers to the ester, ether, alkylation product, glycoside, etc. of the compound described.Note that the term "salt" refers to, for example, salts of mineral acids such as sulfuric acid, hydrochloric acid, or phosphoric acid, salts of organic acids such as maleic acid or methanesulfonic acid, alkali metal salts such as sodium or potassium, alkaline earth metal salts, ammonium salts, etc.The same applies to the optional components described below.

[0031] Examples of the cooling agents include terpenes such as camphor, borneol, geraniol, cineole, anethole, limonene, eugenol, etc. (which may be in the d-, l- or dl-form); essential oils such as eucalyptus oil, bergamot oil, peppermint oil, cool mint oil, spearmint oil, fennel oil, peppermint oil, cinnamon oil, rose oil, and turpentine.

[0032] Examples of the disinfectants include isopropylmethylphenol, chlorhexidine, acrinol, gluconic acid and its derivatives, povidone-iodine, potassium iodide, iodine, triclocarban, triclosan, photosensitizer No. 101, photosensitizer No. 201, alkyldiaminoglycine hydrochloride, piroctoolamine, and miconazole.

[0033] Examples of the preservatives include methyl benzoate, ethyl benzoate, propyl benzoate, sodium benzoate, phenoxyethanol, chlorphenesin, and caprylhydroxamic acid.

[0034] The vitamins may be either water-soluble or oil-soluble, and examples thereof include vitamin B6 such as pyridoxine, pyridoxal, pyridoxamine, 5'-pyridoxal phosphate, and salts thereof (e.g., pyridoxine hydrochloride, pyridoxine acetate, pyridoxal hydrochloride, pyridoxamine hydrochloride); pantothenic acids such as pantothenic acid, calcium pantothenate, pantothenyl alcohol (panthenol), D-panthesine, D-pantethine, coenzyme A, pantothenyl ethyl ether, and salts thereof; nicotinic acid, nicotinic nicotinic acids such as dl-α-tocopherol nicotinate, benzyl nicotinate, methyl nicotinate, β-butoxyethyl nicotinate, 1-(4-methylphenyl)ethyl nicotinate, nicotinamide, and salts thereof; gamma-oryzanol, thiamine, dibenzoylthiamine, thiamine cetyl, thiamine monophosphate, thiamine diphosphate, thiamine triphosphate, and salts thereof (e.g., dibenzoylthiamine hydrochloride, thiamine hydrochloride, thiamine cetyl hydrochloride, thiamine thiocyanate, thiamine lauryl hydrochloride, thiamine Vitamin B1 such as nitrate, thiamine monophosphate, thiamine lysine salt, thiamine triphosphate, thiamine monophosphate phosphate, thiamine diphosphate hydrochloride, and thiamine triphosphate monophosphate; Vitamin B2 such as riboflavin, flavin mononucleotide, flavin adenine dinucleotide, riboflavin butyrate, riboflavin tetrabutyrate, riboflavin 5'-phosphate sodium, riboflavin tetranicotinate, and salts thereof; Vitamin B3 such as biotin, biocytin, and salts thereof. tins; folates such as folic acid, pteroylglutamic acid, and their salts; vitamin B12 such as cyanocobalamin, hydroxocobalamin, deoxyadenosylcobalamin, and their salts; water-soluble vitamin C such as ascorbic acid, dehydroascorbic acid, ascorbic acid phosphate, ascorbic acid-2-glucoside, 3-O-ethyl ascorbic acid, and their salts (e.g., sodium ascorbate, sodium ascorbyl phosphate, magnesium ascorbyl phosphate);Vitamin E such as dl-α-tocopherol, dl-α-tocopherol acetate, dl-α-tocopherol succinate, and dl-α-tocopherol calcium succinate; oil-soluble vitamin C such as ascorbigen-A, ascorbyl stearate, ascorbyl palmitate, L-ascorbyl dipalmitate, and ascorbyl tetra-2-hexyldecanoate; vitamin D such as ergocalciferol and cholecalciferol; vitamin K such as phylloquinone and farnoquinone; and vitamin-like factors such as ferulic acid.

[0035] Examples of the organic acids include gluconic acid, aspartic acid, aminoethylsulfonic acid, citric acid, glutamic acid, succinic acid, oxalic acid, fumaric acid, propionic acid, malic acid, salicylic acid, glycolic acid, phytic acid, tartaric acid, acetic acid, lactic acid, and salts thereof. Examples of the salts include salts of mineral acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, salts of organic acids such as maleic acid and methanesulfonic acid, salts of alkali metals such as sodium and potassium, alkaline earth metal salts, and ammonium salts.

[0036] Examples of the moisturizing components include diglycerin trehalose; polymeric compounds such as sodium hyaluronate, heparinoids, sodium chondroitin sulfate, collagen, elastin, keratin, chitin, and chitosan; amino acids such as glycine, aspartic acid, and arginine; natural moisturizing factors such as sodium lactate, urea, and sodium pyrrolidone carboxylate; lipids such as ceramide, cholesterol, and phospholipids; and plant extracts such as chamomile extract, witch hazel extract, tea extract, and perilla extract.

[0037] Examples of the scrubbing agent include apricot kernel powder, almond shell powder, apricot kernel powder, sodium chloride granules, olive kernel powder, seawater dried granules, candelilla wax, walnut shell powder, cherry kernel powder, coral powder, charcoal powder, hazel shell powder, polyethylene powder, and anhydrous silicic acid.

[0038] Examples of the ultraviolet absorbing component include cinnamic acid-based ultraviolet absorbers such as di-paramethoxycinnamate mono-2-ethylhexanoate glyceryl; paramethoxycinnamate 2-ethylhexyl; dimethoxybenzylidene dioxoimidazolidinepropionate 2-ethylhexyl; 2,2'-methylenebis[6-(2H-benzotriazol-2yl)-4-(1,1,3,3-tetramethylbutyl)phenol]; 2,4-bis-[{4-(2-ethylhexyloxy)-2-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine, diethylhexylbutamidotriazon, 2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine, diethylhexylbutamidotriazon ... benzalmalonate derivative ultraviolet absorbers such as dimethicodiethyl benzalmalonate; octocrylene ultraviolet absorbers such as 2-cyano-3,3-diphenylprop-2-enoic acid 2-ethylhexyl ester; imidazole sulfonic acid derivative ultraviolet absorbers such as 2-phenylbenzimidazole-5-sulfonic acid and disodium phenyldibenzimidazole tetrasulfonate; and benzophenone derivative ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and salts thereof, dihydroxydimethoxybenzophenone, dihydroxybenzophenone, and tetrahydroxybenzophenone.

[0039] Examples of the ultraviolet ray scattering component include inorganic compounds such as hydrous silicic acid, zinc silicate, cerium silicate, titanium silicate, zirconium oxide, cerium oxide, titanium oxide, iron oxide, and silicic anhydride; these inorganic compounds are coated with inorganic powders such as hydrous silicic acid, aluminum hydroxide, mica, and talc; or are composited with resin powders such as polyamide, polyethylene, polyester, polystyrene, and nylon; and further treated with silicone oil, aluminum salt of a fatty acid, or the like.

[0040] Examples of the astringent ingredient include zinc sulfate, aluminum chloride, zinc sulfocarbonate, tannic acid, and the like.

[0041] Examples of the above peptides or derivatives thereof include keratin hydrolyzed peptides, hydrolyzed keratin, collagen, fish-derived collagen, atelocollagen, gelatin, elastin, elastin hydrolyzed peptides, collagen hydrolyzed peptides, hydrolyzed collagen, hydroxypropylammonium chloride hydrolyzed collagen, elastin hydrolyzed peptides, conchiolin hydrolyzed peptides, hydrolyzed conchiolin, silk proteolytic peptides, hydrolyzed silk, sodium lauroyl hydrolyzed silk, soybean proteolytic peptides, hydrolyzed soybean protein, wheat protein, wheat proteolytic peptides, hydrolyzed wheat protein, casein hydrolyzed peptides, acylated peptides (palmitoyl oligopeptide, palmitoyl pentapeptide, palmitoyl tetrapeptide, etc.), and the like.

[0042] Examples of the above amino acids or derivatives thereof include betaine (trimethylglycine), proline, hydroxyproline, arginine, lysine, serine, glycine, alanine, phenylalanine, β-alanine, threonine, glutamic acid, glutamine, asparagine, aspartic acid, cysteine, cystine, methionine, leucine, isoleucine, valine, histidine, taurine, γ-aminobutyric acid, γ-amino-β-hydroxybutyric acid, carnitine, carnosine, creatine, and the like.

[0043] Examples of the cleaning components include amino acid surfactants such as sodium cocoyl glutamate and sodium cocoyl methyl taurate; ether sulfate salts such as sodium laureth sulfate; ether carboxylates such as sodium lauryl ether acetate; sulfosuccinate salts such as sodium alkyl sulfosuccinate; fatty acid alkanolamides such as coconut oil fatty acid monoethanolamide and coconut oil fatty acid diethanolamide; monoalkyl phosphate salts such as sodium lauryl phosphate and sodium polyoxyethylene lauryl ether phosphate; betaine-type amphoteric surfactants such as coconut oil fatty acid amidopropyl dimethylaminoacetate betaine, lauryl dimethylaminoacetate betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, lauryl hydroxysulfobetaine, and lauroyl amidoethyl hydroxyethyl carboxymethyl betaine hydroxypropyl phosphate sodium; and amino acid amphoteric surfactants such as sodium lauryl aminopropionate.

[0044] Examples of the keratin softening ingredient include lactic acid, salicylic acid, gluconic acid, citric acid, malic acid, fruit acid, phytic acid, urea, glycolic acid, and sulfur.

[0045] Examples of the cell activation components include amino acids such as γ-aminobutyric acid; vitamins such as retinol, thiamine, riboflavin, pyridoxine hydrochloride, pantothenic acids, etc.; α-hydroxy acids such as glycolic acid, lactic acid, etc.; tannins, flavonoids, saponin, photosensitizer No. 301, etc.

[0046] Examples of the anti-aging ingredients include pangamic acid, kinetin, ursolic acid, turmeric extract, sphingosine derivatives, silicon, silicic acid, N-methyl-L-serine, and mevalonolactone.

[0047] Examples of the blood circulation promoting component include components derived from plants (e.g., ginseng, angelica, arnica, ginkgo, fennel, Japanese oak, Dutch oak, chamomile, Roman chamomile, carrot, gentian, burdock, rice, hawthorn, shiitake mushroom, ginger, European hawthorn, European juniper, Cnidium rhizome, Swertia japonica, thyme, clove, tangerine peel, chili pepper, angelica tree, peach kernel, spruce, carrot, garlic, butcher's broom, grape, peony, horse chestnut, melissa, yuzu, coix seed, ryokucha, rosemary, rose hip, tangerine peel, angelica tree, spruce, peach, apricot, walnut, corn, etc.); acetylcholine, ichthammol, cantharides tincture, gamma oryzanol, cepharanthine, tolazoline, tocopherol nicotinate, glucosyl hesperidin, etc.).

[0048] Examples of the whitening ingredient include tocopherol, tranexamic acid, nicotinamide, ascorbic acid or a salt thereof, and an ascorbic acid derivative or a salt thereof.

[0049] Examples of the powder components include aluminum starch octenylsuccinate, talc, corn starch, magnesium hydroxide, anhydrous silicic acid, light anhydrous silicic acid, mica, hydroxyapatite, zinc oxide, titanium oxide, nylon powder, charcoal, kaolin, and calamine.

[0050] <ph> The pH of the skin external composition of the present invention is usually 7.0 or more and 12.0 or less, preferably 7.5 or more, 8.0 or more, 8.5 or more, 9.0 or more, 9.5 or more, 10.0 or more, and preferably 11.5 or less, 11.0 or less, 10.5 or less, 10.2 or less. The pH of the skin external composition of the present invention is also preferably 7.5 or more and 11.5 or less, 8.0 or more and 11.5 or less, 8.5 or more and 11.5 or less, 9.0 or more and 11.5 or less, 10.0 or more and 11.5 or less, 7.5 or more and 11.0 or less, 8.0 or more and 11.0 or less, 9.5 or more and 11.0 or less, 7.5 or more and 10.5 or less, 8.0 or more and 10.5 or less, 8.5 or more and 10.5 or less, 9.0 or more and 10.5 or less. This pH can be adjusted, for example, by using a pH adjuster described later.

[0051] <Method of manufacturing the composition for external use on skin> The method for producing the topical skin composition of the present invention is not particularly limited, and the composition can be produced by a conventional method by appropriately selecting and mixing the essential components (A), (B) and (C) and other components (the above-mentioned (D) component, optional components, bases or carriers, additives, etc.) that are mixed as necessary. The topical skin composition of the present invention may be an emulsified composition, a solubilized composition, or a dispersed or dissolved composition.

[0052] <Uses of topical skin composition> The skin topical composition of the present invention is used in products that are applied directly to the skin by coating, spraying, or other methods, or in products that are applied to articles that come into direct contact with the skin, and can be used in soaps and the like for cleaning the skin, and can also be used in cosmetics for the purpose of masking various odors generated on the skin or imparting a pleasant fragrance. The skin topical composition of the present invention used for such purposes can be suitably used as, for example, cleansing agents such as body soaps and face washes, skin care products such as milky lotions and creams, hair care agents such as shampoos, treatments, and dry shampoos, cleansing agents, deodorants, antiperspirants, ointments, sticks, liquids, suspensions, emulsions (milky lotions and creams), gels, liniments, powders, granules, and the like. Among them, the composition of the present invention is preferably a cleansing agent. In addition, the composition of the present invention is useful as a sustained-release fragrance composition because the structure of component (A) is stably maintained in the formulation, and after application to the skin, it gradually cyclizes over time to generate an aromatic substance and can generate a sustained excellent fragrance.

[0053] <Preparation> The skin topical composition of the present invention can be prepared in various formulations by mixing the essential components and the other components described above with a base or carrier commonly used in cosmetics, medicines, and quasi-drugs, and, if necessary, with additives described below, according to a conventional method, and emulsifying or solubilizing as necessary. The formulation form of the skin topical composition of the present invention is not particularly limited, and examples thereof include ointments, liquids, suspensions, emulsions (milks and creams), gels, liniments, lotions, poultices, mists, aerosols, powders, and granules. Among these, liquid to solid formulations are preferred, and it is particularly useful to apply liquids, lotions, ointments, solids, gels, and emulsions. These formulations can be prepared according to conventional methods, such as the methods described in the General Provisions of Preparations in the 18th Revised Japanese Pharmacopoeia.

[0054] Examples of the base or carrier include hydrocarbons, silicone oils, fats and oils, waxes, higher alcohols, lower alcohols, esters, polysaccharides, vinyl polymers, and water.Specifically, liquid paraffin, squalane, petrolatum, gelling hydrocarbons (Plastibase, etc.), ozokerite, α-olefin oligomers, light liquid paraffin and other hydrocarbons; methyl polysiloxane, highly polymerized methyl polysiloxane, cyclic silicone, alkyl-modified silicone, amino-modified silicone, polyether-modified silicone, polyglycerin-modified silicone, silicone / alkyl chain co-modified polyether-modified silicone, silicone / alkyl chain co-modified polyglycerin-modified silicone, polyether-modified branched silicone, polyglycerin-modified branched silicone. Silicone oils such as corn, acrylic silicone, phenyl-modified silicone, and silicone resin; oils and fats such as coconut oil, jojoba oil, olive oil, rice bran oil, and shea butter; waxes such as beeswax, candelilla wax, sunflower wax, and lanolin; higher alcohols such as cetanol, cetostearyl alcohol, stearyl alcohol, behenyl alcohol, octyldodecanol, isostearyl alcohol, phytosterol, and cholesterol; lower alcohols such as ethanol and isopropanol; ethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl cellulose. Examples of the polysaccharides include dextrin and maltodextrin; cellulose derivatives such as pyrmethylcellulose; polyvinylpyrrolidone; carrageenan; polyvinyl butyrate; polyethylene glycol; dioxane; butylene glycol adipate polyester; esters such as diisopropyl adipate, isopropyl myristate, octyldodecyl myristate, isopropyl palmitate, cetyl palmitate, isononyl isononanoate, and pentaerythritol tetra 2-ethylhexanoate; polysaccharides such as dextrin and maltodextrin; vinyl polymers such as carboxyvinyl polymers and alkyl-modified carboxyvinyl polymers; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monopropyl ether; and water.

[0055] The skin topical composition of the present invention preferably contains water as a base, and from the viewpoint of achieving the effects of the invention, the amount of water in the formulation is preferably 30 to 85 mass%, more preferably 40 to 80 mass%, and even more preferably 50 to 72 mass%.

[0056] The bases or carriers described above may be used alone or in combination of two or more. The amounts of the bases or carriers used are appropriately selected from the ranges known to those skilled in the art.

[0057] <Additives> The skin topical composition of the present invention may contain known additives added to cosmetics, pharmaceuticals, and quasi-drugs, such as surfactants, stabilizers, antioxidants, colorants, pearlescent agents, dispersants, chelating agents, pH adjusters, thickeners, irritation reducers, etc., within the scope of not impairing the effects of the present invention. These additives may be used alone or in combination of two or more.

[0058] The surfactant may be any of nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, and the like, and examples thereof include sorbitan fatty acid esters such as sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, diglycerol sorbitan penta-2-ethylhexyl acid, and diglycerol sorbitan tetra-2-ethylhexyl acid; propylene glycol fatty acid esters such as propylene glycol monostearate; hydrogenated castor oil derivatives such as polyoxyethylene hydrogenated castor oil 40 (HCO-40), polyoxyethylene hydrogenated castor oil 50 (HCO-50), polyoxyethylene hydrogenated castor oil 60 (HCO-60), and polyoxyethylene hydrogenated castor oil 80; polyoxyethylene monolaurate, Examples of suitable surfactants include polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene (20) sorbitan monostearate (polysorbate 60), polyoxyethylene (20) sorbitan monooleate (polysorbate 80), and polyoxyethylene (20) sorbitan isostearate; polyoxyethylene monococoate glyceryl; glycerin alkyl ethers; alkyl glucosides; polyoxyalkylene alkyl ethers such as polyoxyethylene cetyl ether; amines such as stearylamine and oleylamine; silicone surfactants such as polyoxyethylene-methylpolysiloxane copolymers, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, and PEG-9 polydimethylsiloxyethyl dimethicone. Of these, nonionic surfactants are preferred, and hydrogenated castor oil derivatives, polyoxyethylene sorbitan fatty acid esters, and polyoxyalkylene alkyl ethers are more preferred.

[0059] Examples of the stabilizer include sucrose fatty acid esters, hydrogenated castor oil isostearate, hydrogenated castor oil isostearate, mannitol, cyclodextrin, sodium stearoyl methyl taurate, and the like.

[0060] Examples of the antioxidant include dibutylhydroxytoluene, butylhydroxyanisole, sorbic acid, sodium sulfite, ascorbic acid, erythorbic acid, L-cysteine ​​hydrochloride, sodium pyrosulfite, polyphenols, and fullerene.

[0061] Examples of the colorant include inorganic pigments and natural dyes.

[0062] Examples of the pearly luster imparting agent include ethylene glycol distearate, ethylene glycol monostearate, and triethylene glycol distearate.

[0063] Examples of the dispersing agent include di(phytosteryl-2-octyldodecyl) N-lauroyl-L-glutamate, di(phytosteryl-behenyl-2-octyldodecyl) N-lauroyl-L-glutamate, diethylhexyl sodium sulfosuccinate, polyglyceryl polyricinoleate, dimer dilinoleate (phytosteryl / isostearyl / cetyl / stearyl / behenyl), lecithin, acrylic acid / alkyl methacrylate copolymer, (acrylates / ethylhexyl acrylate / dimethicone methacrylate) copolymer, and the like.

[0064] Examples of the chelating agent include EDTA disodium salt, EDTA calcium disodium salt, and the like.

[0065] Examples of the pH adjuster include inorganic acids (hydrochloric acid, sulfuric acid, etc.), organic acids (lactic acid, sodium lactate, citric acid, sodium citrate, succinic acid, sodium succinate, etc.), and the like.

[0066] Examples of the thickener include vinyl thickeners such as polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, (acrylates / alkyl acrylate (C10-30)) crosspolymer, (hydroxyethyl acrylate / Na acryloyldimethyl taurate) copolymer, and (ammonium acryloyldimethyl taurate / vinylpyrrolidone) copolymer; cellulose thickeners such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, and carboxyethyl cellulose; guar gum, pectin, pullulan, gelatin, locust bean gum, carrageenan, agar, xanthan gum, acrylate / alkyl methacrylate copolymer, polyethylene glycol, bentonite, alginic acid, propylene glycol alginate, macrogol, sodium chondroitin sulfate, hyaluronic acid, and sodium hyaluronate. Of these, vinyl-based thickeners and cellulose-based thickeners are preferred, and carboxyvinyl polymers, (acrylates / C10-30 alkyl acrylate) crosspolymers, polyvinylpyrrolidone, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, and carboxyethyl cellulose are more preferred.

[0067] Examples of the irritation reducer include licorice extract, sodium alginate, gum arabic, polyvinylpyrrolidone, and the like.

[0068] [Stabilization method] The present invention also includes a method for stabilizing (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and having a hydroxy group at position 4 or 5 in a composition for external use on skin, the method comprising blending (B) a fatty acid or a salt thereof, and (C) a neutralizing agent in the composition and adjusting the neutralization rate of the fatty acid to 70% to 120%.

[0069] Since the component (A) in the composition for external use on the skin is a compound that becomes aromatic by cyclization under lipase, acidic conditions, etc., it is expected that by applying the composition for external use on the skin, cyclization will proceed gradually under the influence of lipase in the skin, and the fragrance will be emitted for a long time. However, as described above, the present inventor faced the problem that the composition containing the component (A) may cyclize hydroxy fatty acid, etc. in the preparation depending on the composition, and release the fragrance before application to the skin, and conducted intensive research to solve this problem. As a result, it was found that the component (A) in the composition can be stabilized by further blending (B) fatty acid or its salt, and (C) neutralizing agent, and the neutralization rate of the fatty acid is adjusted to 70% to 120%, and the method of the present invention can be completed.

[0070] The explanations for each component that can be used in the method of the present invention, such as component (A), component (B), component (C), and other components that may be blended, in the section on the topical skin composition of the present invention described above can be applied as is. EXAMPLES

[0071] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0072] The cleaning compositions of Examples 1 to 6 and Comparative Examples 1 and 2 were prepared according to the usual method using the formulations shown in Table 1 below. 30 g of each formulation was filled into a 30 ml glass bottle and stored at 40°C for 17 hours, after which a specialist panel (N=3) smelled the formulations and evaluated the presence or absence of lactone odor according to the following criteria. The pH of the formulations was also measured at 25°C. The results are shown in Table 1.

[0073] (Evaluation Criteria) 0: No lactone smell at all 1: A slight lactone odor is detected 2: Slight lactone smell 3: Lactone odor is detected 4: Strong lactone odor [Table 1]

[0074] As shown in Table 1, in Comparative Examples 1 and 2 (fatty acid neutralization rate of 50-60%), sodium 4-hydroxyundecanoate was converted to undecalactone during storage at 40°C for 17 hours, resulting in the release of a lactone odor (score 4), whereas in Examples 1-6 (fatty acid neutralization rate of 70-120%), no lactone odor was released even after half a day of storage at 40°C (score 0), indicating that sodium 4-hydroxyundecanoate was not cyclized and was stably maintained in the formulation. No significant change in pH was observed before and after storage in any of the formulations.

[0075] Examples of formulations for the topical skin composition of the present invention are given below.

[0076] <Formulation example 1:: Alkaline tube face wash 1> Lauric acid 3% by weight Myristic acid 7% by weight Palmitic acid 6% by weight Stearic acid 15% by weight Potassium hydroxide 5.8% by weight Sodium lauryl ether sulfate 1.5% by weight Ethylene glycol distearate 2% by weight Glycerin 9% by weight Diglycerin 2% by weight Sorbitol 3% by weight PEG-32 2% by weight Polyquaternium-33 0.5% by weight Ceramide 3 0.01% by weight EDTA-2Na 0.05% by weight BHT 0.1% by weight Fragrance 0.1% by weight Sodium 4-hydroxyundecanoate 0.5% by weight Water remaining Total 100% by weight Neutralization rate 79% pH 9.2

[0077] <Formulation example 2: Alkaline tube face wash> Lauric acid 3% by weight Myristic acid 7% by weight Stearic acid 17% by weight Potassium hydroxide 5.4% by weight Cocamidopropyl betaine 1% by weight Lauryl hydroxysultaine 0.5% by weight Glyceryl stearate (SE) 1% by weight Glycerin 12% by weight BG 4% by weight Cocamide DEA 0.5% by weight Polyquaternium-7 0.3% by weight Sodium dilauroyl glutamate lysine 0.5% by weight EDTA-2Na 0.05% by weight d-δ-tocopherol 0.1% by weight Sodium benzoate 0.2% by weight Sodium 4-hydroxyundecanoate 1% by weight Water remaining Total 100% by weight Neutralization rate 87% pH 10

[0078] <Formulation example 3: Alkaline body soap> Lauric acid 7% by weight Myristic acid 7% by weight Palmitic acid 1% by weight Potassium hydroxide 4.4% by weight Hydroxypropyl methylcellulose 0.5% by weight PG 3% by weight DPG 3% by weight Sodium lauryl ether acetate 1.5% by weight Sodium tetradecene sulfonate 1% by weight Propylene glycol laurate 1% by weight Cocamide methyl MEA 2% by weight Polyquaternium-47 0.3% by weight Polyquaternium-10 0.3% by weight Phenoxyethanol 0.3% by weight Menthol 0.05% by weight Sodium 4-hydroxyundecanoate 0.7% by weight Water remaining Total 100% by weight Neutralization rate 107% pH 10.6

[0079] <Formulation example 4: Beauty cream> Stearic acid 1% by weight Triethanolamine 0.56% by weight Stearyl alcohol 1% by weight Polyoxyethylene hydrogenated castor oil (60E.O.) 0.3% by weight Lipophilic glyceryl monostearate 0.4% by weight Sugar squalane 2% by weight Caprylic / capric triglyceride 2% by weight Jojoba oil 1% by weight Polyacrylic acid amide, light liquid isoparaffin and polyoxy Mixture of ethylene lauryl ether (7E.O.) and purified water 0.6% by weight Acrylic acid / alkyl methacrylate copolymer 0.1% by weight Glycerin 3% by weight 1,3-butylene glycol 10% by weight Sodium 4-hydroxyundecanoate 0.3% by weight 1,3-propanediol 3% by weight Water remaining Total 100% by weight Neutralization rate 72% pH 7.5 [Industrial Applicability]

[0080] According to the present invention, in a composition for external use on the skin containing a hydroxy fatty acid such as 4-hydroxyundecanoic acid, it is possible to provide a formulation having excellent stability without the hydroxy fatty acid being cyclized in the formulation and releasing an aroma.< / ph>

Claims

1. (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4- or 5-position; (B) a fatty acid or a salt thereof, and (C) Neutralizing agent and having a neutralization rate of fatty acids of 70% to 120%.

2. The composition for external application to skin according to claim 1, wherein component (A) comprises 4-hydroxyundecanoic acid or a salt thereof.

3. 3. The composition for external use on skin according to claim 1, wherein component (B) comprises a fatty acid having 12 to 22 carbon atoms or a salt thereof.

4. The topical skin composition according to claim 1 or 2, wherein (C) the neutralizing agent comprises potassium hydroxide and / or sodium hydroxide.

5. (A) A composition for external use on the skin containing a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4- or 5-position, (B) a fatty acid or a salt thereof, and (C) Neutralizing agent Combined with and adjusting the neutralization rate of fatty acids to 70% to 120%. A method for stabilizing (A) a hydroxy fatty acid or a salt thereof having 10 or more carbon atoms and a hydroxy group at the 4- or 5-position in the above composition.

6. The stabilization method according to claim 5 , wherein the component (A) comprises 4-hydroxyundecanoic acid or a salt thereof.

7. The stabilization method according to claim 5 or 6, wherein the component (B) comprises a fatty acid having 12 to 22 carbon atoms or a salt thereof.

8. The stabilization method according to claim 5 or 6, wherein the (C) neutralizing agent comprises potassium hydroxide and / or sodium hydroxide.

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