Oil-in-water type emulsified cosmetic

Abstract

[Problem] To provide an oil-in-water type emulsified cosmetic that exhibits excellent stability. [Solution] An oil-in-water type emulsified cosmetic comprises (A) an α-hydroxy acid or a salt thereof, (B) a carboxyvinyl polymer, (C) an oily component, and (D) water. The percentage content of (A) the component with respect to the total amount of the cosmetic is 1 mass% or more. (C) The component includes (c-1) a polar oil. The percentage content of (c-1) the component is 50 mass% or more with respect to the total amount of (C) the component. The pH of the cosmetic is 5.0 or less at 30°C.

Description

Oil-in-water type emulsified cosmetic

[0001] The present invention relates to an oil-in-water type emulsified cosmetic. Specifically, the present invention relates to an oil-in-water type emulsified cosmetic containing an α-hydroxy acid.

[0002] Conventionally, for example, in order to obtain the effect of a drug in a cosmetic containing the drug, it is known to adjust the pH of the cosmetic to a specific range (for example, 5.0 or less) (for example, Patent Document 1). Further, in order to set such a pH range, when an α-hydroxy acid is contained, the thickening effect by a thickener may not be appropriately obtained, and it has been found that the viscosity of the cosmetic may decrease, gelation may occur, or separation may occur. Such a phenomenon tends to occur when a large amount of polar oil is contained, and particularly tends to occur in a high-temperature environment (for example, 50°C), and there has been room for improvement. Therefore, improvement in stability has been demanded in a cosmetic having a specific pH range (for example, 5.0 or less) by blending an α-hydroxy acid.

[0003] JP-A-2006-298850

[0004] The present inventors have surprisingly found that good stability can be obtained in a cosmetic containing an α-hydroxy acid or its salt when specific composition conditions are satisfied and it is in a specific pH range. The present invention is based on these findings.

[0005] The present invention provides the following: [1] An oil-in-water emulsion cosmetic comprising (A) an α-hydroxy acid or a salt thereof, (B) a carboxyvinyl polymer, (C) an oily component, and (D) water, wherein the content of component (A) is 1% by mass or more with respect to the total amount of the cosmetic, component (C) contains (c-1) a polar oil, the content of component (c-1) is 50% by mass or more with respect to the total amount of component (C), and the pH of the cosmetic at 30°C is 5.0 or less. [2] The oil-in-water emulsion cosmetic according to [1], further comprising (E) an agent selected from the group consisting of (e-1) tranexamic acid and (e-2) alkoxysalicylic acid. [3] The oil-in-water emulsion cosmetic according to [1] or [2], wherein the content of component (C) is 10 to 40% by mass with respect to the total amount of the cosmetic. [4] An oil-in-water emulsion cosmetic according to any one of [1] to [3], wherein component (c-1) contains an ultraviolet absorber. [5] An oil-in-water emulsion cosmetic according to [4], wherein the content of the ultraviolet absorber is 1% by mass or more with respect to the total amount of the cosmetic. [6] An oil-in-water emulsion cosmetic according to any one of [1] to [5], further comprising (F) a nonionic surfactant. [7] An oil-in-water emulsion cosmetic according to any one of [1] to [6], further comprising (G) a higher alcohol. [8] An oil-in-water emulsion cosmetic according to any one of [1] to [7], which is a sunscreen cosmetic.

[0006] According to the present invention, it is possible to provide an oil-in-water emulsion cosmetic composition with improved stability. Detailed description of the invention

[0007] The oil-in-water emulsion cosmetic composition according to the present invention (hereinafter sometimes simply referred to as "cosmetic composition") comprises (A) an α-hydroxy acid or a salt thereof, (B) a carboxyvinyl polymer, (C) an oily component, and (D) water. Each of these components, and any further components that may be added, are described below.

[0008] (A) α-hydroxy acid or salt thereof The cosmetic composition according to the present invention comprises (A) an α-hydroxy acid or a salt thereof (hereinafter sometimes referred to as component (A), and the same applies to other components). The α-hydroxy acid that can be incorporated into the cosmetic composition of the present invention is not particularly limited, but examples include citric acid, succinic acid, glycolic acid, lactic acid, malic acid, tartaric acid, glyceric acid, pyruvic acid, mandelic acid, etc. One or more of these can be used as the α-hydroxy acid. Preferably, the α-hydroxy acid contains one or more selected from the group consisting of citric acid, succinic acid, glycolic acid, and lactic acid. Preferably, the α-hydroxy acid contains citric acid or glycolic acid, and is particularly preferably citric acid. The α-hydroxy acid may exist in the cosmetic composition in the form of a salt. Examples of salts are not limited to these, but include alkali metal salts, alkaline earth metal salts, etc., and for example, the α-hydroxy acid may exist in the cosmetic composition in the form of a sodium salt.

[0009] (A) Component is present in an amount of 1% by mass or more relative to the total amount of the cosmetic, preferably 1 to 7% by mass, and particularly preferably 1 to 5% by mass.

[0010] (B) Carboxyvinyl Polymer The cosmetic composition of the present invention comprises (B) carboxyvinyl polymer. Carboxyvinyl polymer is a copolymer of acrylic acid. Commercially available carboxyvinyl polymers can be used, for example, Carbopol® 940, Carbopol® 941, Carbopol® 980, or Carbopol® 981 (all manufactured by Lubrizol), AQUPEC® HV-501E, AQUPEC® HV-505E (manufactured by Sumitomo Seika Co., Ltd.), Hibiscus Wako® 103, Hibiscus Wako® 104, Hibiscus Wako® 105 (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The above carboxyvinyl polymers can be used alone or in combination of two or more.

[0011] Component (B) is preferably present in an amount of 0.01 to 2% by mass, more preferably 0.05 to 1% by mass, and particularly preferably 0.1 to 0.5% by mass, relative to the total amount of the cosmetic composition. In the cosmetic composition of the present invention, although not bound by theory, it is presumed that component (B) can suppress changes in viscosity under high-temperature environments, suppress the movement of emulsion particles, and suppress the occurrence of emulsion coalescence of emulsion particles.

[0012] (C) Oily component The cosmetic composition of the present invention comprises (C) an oily component. Furthermore, component (C) includes (c-1) a polar oil and (c-2) a non-polar oil. In this specification, component (C) does not contain higher alcohols.

[0013] (c-1) Polar oils As polar oils, ester oils and UV absorbers can be used. As polar oils, any oil commonly used in cosmetics can be used. Examples of ester oils include pentaerythrityl tetraethylhexanoate, cetyl ethylhexanoate, jojoba oil, phytosteryl / octyldodecyl lauroyl glutamate, triisostearin, glyceryl diisostearate, triethylhexanoin, phytosteryl / behenyl dimer dilinoleate, phytosteryl / isostearyl / cetyl / stearyl / isostearyl / cetyl / stearyl / behenyl dimer dilinoleate, isopropyl palmitate, and macadamia nut oil. Phytosteryl fatty acids, pentaerythrityl tetra(behenate / benzoate / ethylhexanoate), ethylhexyl palmitate, myristyl myristate, isopropyl myristate, tripylene glycol dipivalate, diisopropyl sebacate, isodecyl neopentanoate, octyl octanoate, nonyl nonanoate, cetyl octanoate, octyldodecyl myristate, butyl stearate, hexyl laurate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate L, lanolin acetate, isocetyl stearate, isocetyl isostearate, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, tripropylene glycol pivalate, diisostearyl malate, glyceryl di-2-heptylundecanoate, glyceryl diisostearate, trimethylolpropane tri-2-ethylhexanoate, Trimethylolpropane triisostearate, pentaerythritol tetra-2-ethylhexanoate, glycerin tri-2-ethylhexanoate, glycerin trioctanoate, glycerin triisopalmitate, cetyl 2-ethylhexanoate-2-ethylhexyl palmitate, glycerin trimyristate, glyceride tri-2-heptylundecanoate, methyl castor oil fatty acid ester, oleyl oleate, acetoglyceride, 2-heptylundecyl palmitate, diisobutyl adipate,Examples include N-lauroyl-L-glutamic acid-2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, 2-ethylhexyl succinate, and triethyl citrate. Of these, (c-1) it is preferable that the polar oil contains triethylhexanoin.

[0014] Examples of UV absorbers include benzoic acid derivatives such as ethyl para-aminobenzoate (PABA), ethyl-dihydroxypropyl PABA, ethylhexyl-dimethyl PABA, glyceryl PABA, PEG-25-PABA, and diethylaminohydroxybenzoyl hexyl benzoate; salicylic acid derivatives such as homosalate, ethylhexyl salicylate (octyl salicylate), dipropylene glycol salicylate, and TEA salicylate; octyl methoxycinnamate, ethylhexyl methoxycinnamate, isopropyl methoxycinnamate, and methoxycinnamate. Cinnamic acid derivatives such as isoamyl cinnamate, cinnamoxate, DEA methoxycinnamate, diisopropyl methylcinnamate, glyceryl-ethylhexanoate-dimethoxycinnamate, di-(2-ethylhexyl)-4'-methoxybenzalmalonate; dibenzoylmethane derivatives such as 4-tert-butyl-4'-methoxydibenzoylmethane; β,β-diphenyl acrylate derivatives such as octocrylene; benzophenone-1, benzophenone-2, benzophenone-3 or oxybenzone, benzophenone-4, benzophenone-5, etc. Benzophenone derivatives such as benzophenone-6, benzophenone-8, benzophenone-9, and benzophenone-12; benzylidene derivatives such as 3-benzylidene camphor, 4-methylbenzylidene camphor, benzylidene camphor sulfonic acid, benzalkonium camphor methosulfate, terephthalylidene disodium camphor sulfonic acid, and polyacrylamide methylbenzylidene camphor; phenylbenzimidazole derivatives such as phenylbenzimidazole sulfonic acid and phenyldibenzimidazole tetrasulfonate disodium; bis Triazine derivatives such as ethylhexyloxyphenol methoxyphenyl triazine, ethylhexyl triazone (e.g., "Ubinal T150"; BASF), diethylhexylbutamide triazone, 2,4,6-tris(diisobutyl-4'-aminobenzalmalonate)-s-triazine, and 2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine; phenylbenzotriazole derivatives such as drometrizole trisiloxane and methylenebis(benzotriazolyltetramethylbutylphenol);Examples include anthranyl derivatives such as menthyl anthranilate; imidazoline derivatives such as ethylhexyldimethoxybenzylidenedioxoimidazoline propionate; benzalmalonate derivatives such as polyorganosiloxanes having a benzalmalonate functional group; and 4,4-diarylbutadiene derivatives such as 1,1-dicarboxy(2,2'-dimethylpropyl)-4,4-diphenylbutadiene. Of these, it is preferable that the ultraviolet absorber contains at least one selected from the group consisting of ethylhexyl methoxycinnamate, bis-ethylhexyloxyphenol methoxyphenyl triazine, and diethylamino hydroxybenzoyl hexyl benzoate.

[0015] (c-2) Nonpolar oils Examples of nonpolar oils include hydrocarbon oils and silicone oils. Any oil commonly used as a cosmetic can be used as the nonpolar oil. Examples of hydrocarbon oils include hydrogenated polydecene, liquid paraffin, squalane, squalene, paraffin, isoparaffin, ceresin, isododecane, isohexadecane, ozokerite, pristane, petrolatum, etc. Of these, it is preferable that the (c-2) nonpolar oil contains hydrogenated polydecene or isododecane.

[0016] Examples of silicone oils include linear polysiloxanes such as dimethylpolysiloxane (dimethicone), methylphenylpolysiloxane, methylhydrogenpolysiloxane, and diphenylsiloxyphenyl trimethicone, as well as cyclic polysiloxanes such as decamethylpolysiloxane, dodecamethylpolysiloxane, and tetramethyltetrahydrogenpolysiloxane. Of these, it is preferable that the (c-2) nonpolar oil contains dimethylpolysiloxane or diphenylsiloxyphenyl trimethicone. It is preferable that the dimethylpolysiloxane is high molecular weight dimethylpolysiloxane (e.g., 6cs, 20cs).

[0017] In the cosmetic composition of the present invention, the content of component (C) is preferably 10 to 40% by mass, and more preferably 20 to 40% by mass, based on the total amount of the cosmetic composition.

[0018] In the cosmetic composition of the present invention, component (C) contains a polar oil (c-1), and the content of component (c-1) is 50% by mass or more of the total amount of component (C). Furthermore, it is preferable that the content of component (c-1) is 80% by mass or less of the total amount of component (C).

[0019] (c-1) Component preferably contains an ultraviolet absorber. Furthermore, if the cosmetic composition contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 3% by mass or more, more preferably 5 to 30% by mass, and even more preferably 9 to 20% by mass, based on the total amount of the cosmetic composition.

[0020] (D) Water The oil-in-water emulsion cosmetic composition of the present invention comprises (D) water. As the water, water used for cosmetics, quasi-drugs, etc., can be used, for example, purified water, ion-exchanged water, tap water, etc. The content of component (D) is preferably 20 to 80% by mass, more preferably 35 to 70% by mass, based on the total amount of the cosmetic composition.

[0021] The cosmetic composition according to the present invention contains components (A) to (D), but its pH must be within a specific range. Specifically, the pH of the cosmetic composition according to the present invention at 30°C is 5.0 or less, preferably 3.0 to 5.0, and more preferably 4.0 to 5.0. By including component (A) in the cosmetic composition according to the present invention having such a pH, the effect of improving the appearance of pores can also be obtained.

[0022] (E) A drug selected from the group consisting of tranexamic acid and alkoxysalicylic acid The cosmetic composition of the present invention may optionally contain a drug selected from the group consisting of (E) tranexamic acid and alkoxysalicylic acid. The cosmetic composition of the present invention may contain both (e-1) tranexamic acid and (e-2) alkoxysalicylic acid.

[0023] Tranexamic acid is trans-4-aminomethylcyclohexancarboxylic acid. Alternatively, tranexamic acid may be a tranexamic acid derivative or a salt thereof. Examples of such tranexamic acid derivatives or salts thereof include tranexamic acid esters (e.g., vitamin esters such as vitamin A ester, vitamin E ester, vitamin C ester, and vitamin D ester, phenyl esters, hydroquinone esters, gentisic acid esters, etc.), tranexamic acid amide (methylamide or its salts, etc.), tranexamic acid dimers, etc., with tranexamic acid being preferred. Examples of their salts include metal salts such as magnesium salts, calcium salts, sodium salts, and potassium salts; and inorganic salts such as phosphates, hydrochlorides, hydrobromides, and sulfates. One or more of these can be included in the formulation.

[0024] (E) When tranexamic acid is included as an ingredient, the content of tranexamic acid is preferably 0.1 to 5% by mass, and more preferably 0.5 to 3.5% by mass, based on the total amount of the cosmetic.

[0025] Examples of alkoxysalicylic acids include 3-methoxysalicylic acid, 3-ethoxysalicylic acid, 4-methoxysalicylic acid, 4-ethoxysalicylic acid, 4-propoxysalicylic acid, 4-isopropoxysalicylic acid, 4-butoxysalicylic acid, 5-methoxysalicylic acid, 5-ethoxysalicylic acid, and 5-propoxysalicylic acid, with 4-methoxysalicylic acid being preferred.

[0026] The alkoxysalicylic acid is preferably a salt. The type of salt is not particularly limited as long as it is a pharmaceutically acceptable salt, but examples include alkali metal salts such as sodium salt, potassium salt, and lithium salt; alkaline earth metal salts such as calcium salt and magnesium salt; ammonium salt; amino acid salt, etc. Potassium salt is preferred, and potassium 4-methoxysalicylate is even more preferred from the viewpoint of cosmetic effects and availability.

[0027] (E) When alkoxysalicylic acid is included as component, the content of alkoxysalicylic acid is preferably 0.1 to 10% by mass, more preferably 0.3 to 8% by mass, and even more preferably 0.5 to 3.5% by mass, based on the total amount of the cosmetic.

[0028] (F) Nonionic surfactant The cosmetic composition of the present invention may optionally contain (F) a nonionic surfactant (hereinafter sometimes simply referred to as component (F)). Any nonionic surfactant that can be used as a cosmetic composition can be used as component (F). Examples of nonionic surfactants include polyethylene glycol fatty acid esters, polyoxyethylene fatty acid glyceryl, polyoxyethylene-methylpolysiloxane copolymer, fatty acid polyoxyethylene sorbitan, polyoxyethylene alkyl ether, maltitol hydroxyaliphatic alkyl ether, alkylated polysaccharide, alkyl glucoside, sucrose fatty acid ester, polyoxyethylene hydrogenated castor oil glyceryl, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene-polyoxypropylene block copolymer, tetrapolyoxyethylene-tetrapolyoxypropylene-ethylenediamine condensate, polyoxyethylene-beeswax-lanolin derivative, alkanolamide, polyoxyethylene-propylene glycol fatty acid ester, polyoxyethylene-alkylamine, polyoxyethylene-fatty acid amide, alkylethoxydimethylamine oxide, trioleyl phosphoric acid, and the like. In the cosmetic composition of the present invention, component (F) preferably contains a hydrophilic nonionic surfactant with an HLB of 8 or higher, such as beheneth-20, polysorbate 60, or PEG-40 stearate. Particularly preferred examples are listed below. One or more nonionic surfactants can be used.

[0029] The content of component (F) is preferably 0.1 to 20% by mass, more preferably 0.3 to 10% by mass, and more preferably 0.5 to 5% by mass, based on the total amount of the cosmetic.

[0030] (G) Higher Alcohols The cosmetic composition of the present invention may optionally contain (G) higher alcohols. The higher alcohol is not particularly limited as long as it is a higher alcohol with 6 or more carbon atoms that can be used as a cosmetic. Examples of higher alcohols include dodecanol (lauryl alcohol), toridodecanol, tetradodecanol (myristyl alcohol), pentadecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), nonadecanol, eicosanol (arachidyl alcohol), henicosanol, docosanol (behenyl alcohol), tricosanol, tetracosanol (carnabyl alcohol), pentacosanol, hexacosanol (ceryl alcohol), etc. As (F) component, one of the above can be used alone or two or more can be used.

[0031] In this invention, it is preferable to combine two or more higher alcohols, and a mixture with a melting point of 50°C or higher is particularly preferred in terms of stability. For example, a combination of stearyl alcohol and behenyl alcohol is particularly preferred.

[0032] The content of component (G) is preferably 0.1 to 20% by mass, more preferably 0.3 to 10% by mass, and more preferably 0.5 to 5% by mass, based on the total amount of the cosmetic.

[0033] (G) The higher alcohol preferably forms an aggregate having a lamellar liquid crystal structure (also called "α-gel") with (F) the nonionic surfactant and (D) water. Although not limited to this, the mixing ratio of (F) the nonionic surfactant and (G) the higher alcohol is preferably in the range of (F):(G) = 1:2 to 1:25 (molar ratio).

[0034] According to the present invention, changes in viscosity under high-temperature conditions (50°C) can be suppressed, and the occurrence of gelation or separation can be suppressed. Therefore, according to the present invention, it is possible to provide an oil-in-water emulsion cosmetic composition with improved stability under high-temperature conditions (50°C).

[0035] Furthermore, the cosmetic composition according to the present invention may contain other components as needed, in addition to the above components. Examples of such components include water-soluble thickeners other than component (B), powder components, humectants, film-forming agents, pH adjusters, surfactants other than component (F), preservatives, chelating agents, stabilizers, colorants, fragrances, and the like.

[0036] The cosmetic composition of the present invention may further contain water-soluble thickeners other than component (B) as needed. Examples of such water-soluble thickeners include: plant-derived polymers such as gum arabic, tragacanth gum, and galactan; microbial polymers such as xanthan gum, dextran, succinoglycan, pullulan, and gellan gum; starch-derived polymers such as carboxymethyl starch; cellulosic polymers such as methylcellulose, nitrocellulose, ethylcellulose, and sodium carboxymethylcellulose; alginic acid-derived polymers such as sodium alginate; vinyl-derived polymers such as polyvinyl alcohol and polyvinylpyrrolidone; polyoxyethylene-derived polymers such as polyethylene glycol; polyoxyethylene polyoxypropylene copolymer polymers; and sodium polyacrylate. Examples include thorium, polyethyl acrylate, polyacrylamide compounds (e.g., poly-2-acrylamide-2-methylpropanesulfonic acid, polymethacryloyloxytrimethylammonium, (acryloyldimethyltaurate ammonium / VP) copolymer, (dimethylacrylamide / acryloyldimethyltaurate sodium) crosspolymer, etc.), acrylic acid / alkyl methacrylate copolymers (alkyl-modified carboxyvinyl polymers, e.g., (acrylates / alkyl (C10-30) acrylate crosspolymer)), and other acrylic polymers; polyethyleneimines, or cationic polymers.

[0037] The cosmetic composition of the present invention may contain one of these water-soluble thickeners alone, or two or more of them. Furthermore, the water-soluble thickener is preferably selected from the group consisting of microbial polymers and acrylic polymers, and more preferably one or more selected from the group consisting of alkyl-modified carboxyvinyl polymers, xanthan gum, and sodium polyacrylate. Furthermore, the water-soluble thickener is preferably contained in an amount of 0.01 to 3% by mass, more preferably 0.05 to 2% by mass, and particularly preferably 0.1 to 1% by mass, based on the total mass of the cosmetic composition.

[0038] The powder component in this invention can be arbitrarily selected from powder components commonly used in cosmetics. Examples of such powder components include inorganic powders (e.g., titanium dioxide, silica, talc, kaolin, sericite, vermiculite, magnesium carbonate, calcium carbonate, diatomaceous earth, magnesium silicate, calcium silicate, aluminum silicate, barium silicate, strontium silicate, tungstate metal salts, hydroxyapatite, zeolite, boron nitride, ceramic powder, iron oxide, sericite, etc.); organic powders (e.g., polyamide resin powder (nylon powder), polyethylene powder, polymethyl methacrylate powder, polystyrene powder, styrene-acrylic acid copolymer resin powder, benzoguanamine resin powder, polytetrafluoroethylene powder, cellulose powder, etc.); inorganic white pigments (e.g., zinc oxide, etc.); inorganic red pigments (e.g., iron titanate, etc.); inorganic purple pigments (e.g., mango violet, cobalt violet, etc.); inorganic green pigments (e.g., chromium oxide, chromium hydroxide, cobalt titanate, etc.); inorganic blue pigments (e.g., ultramarine, Prussian blue, etc.); and metal powder pigments. Additionally, pearl pigments such as titanium dioxide-coated mica (titanium mica), titanium dioxide-coated bismuth oxychloride, titanium dioxide-coated talc, colored titanium dioxide-coated mica, muscovite, synthetic mica, phlogopite, red mica, biotite, thiamite, bismuth oxychloride, and fish scale foil can also be used.

[0039] (F) Surfactants other than component (F) can be surfactants commonly used in cosmetics, and may include anionic surfactants, cationic surfactants, or amphoteric surfactants.

[0040] In the cosmetic according to the present invention, the content rate of the powder component is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total mass of the cosmetic.

[0041] Examples of the humectant include ethylene glycol, diethylene glycol, dipropylene glycol, 1,3-butylene glycol, glycerin, hexamethylene glycol, isoprene glycol, polyethylene glycol, polypropylene glycol, hyaluronic acid, xylitol, sorbitol, maltitol, diglycerin (EO) PO adduct, and the like.

[0042] Examples of the film-forming agent include dimethicone / aminopropyldimethicone and the like.

[0043] Examples of the pH adjuster include hydrochloric acid and sodium hydroxide.

[0044] Examples of the preservative include phenoxyethanol, chlorphenesin, benzoic acid, salicylic acid, sorbic acid, alkyl parabenzoate, hexachlorophene, ε-polylysine, and the like.

[0045] The type of the cosmetic of the present invention and the method for producing the cosmetic are not particularly limited. According to the present invention, the stability of a cosmetic containing a large amount of polar oil as an oily component can be improved. Therefore, the cosmetic according to the present invention can be widely applied to cosmetics containing a large amount of polar oil, and the dosage form is not particularly limited, and it can be a lotion, emulsion, cream, gel, or the like. Further, the cosmetic of the present invention is preferably, for example, a sunscreen cosmetic such as a sunscreen cream, a sunscreen lotion, a base cosmetic having a sunscreen effect, a foundation, or the like.

[0046] The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples. Unless otherwise specified, the content is expressed in mass% based on the total amount.

[0047] [Examples 1 to 5, Comparative Examples 1 to 3, and Reference Example] Cosmetics of each example, each comparative example, and the reference example were prepared with the formulations shown in Table 1 or Table 2. Also, to evaluate stability, the viscosity and pH were measured after standing for 4 weeks at 25°C, 50°C, or under a low-temperature - high-temperature cycle. The pH was measured at 30°C using a commercially available pH meter. The viscosity was measured at 30°C using a B-type viscometer. In the low-temperature - high-temperature cycle, the cosmetic was stored for 4 weeks with a temperature cycle of 0°C to 45°C.

[0048] Further, the performance of these cosmetics was evaluated as follows.

[0049] [Viscosity Stability] (1) Calculate the difference between the viscosity value after standing for 4 weeks at 25°C and the viscosity value after standing for 4 weeks at 50°C. (2) Calculate the difference between the viscosity value after standing for 4 weeks at 25°C and the viscosity value after standing for 4 weeks under the low-temperature - high-temperature cycle. And (3) Observe the cosmetic. By doing so, the viscosity stability was evaluated. The evaluation of viscosity stability was carried out according to the following criteria. A: In both (1) and (2), the difference in viscosity values was less than 1,000 mPa·s, and in (3), the state of the cosmetic was stable. B: The difference in viscosity value in either (1) or (2) was 1,000 mPa·s or more and less than 3,000 mPa·s, and in (3), no gelation or separation occurred and the cosmetic was generally stable. C: The difference in viscosity value in either (1) or (2) was 3,000 mPa·s or more, or gelation or separation was observed in (3).

[0050] As a reference example, a similar evaluation was performed on a cosmetic product in which the total content of oily components was less than 10% by mass relative to the total amount of cosmetic product, and the content of polar oil relative to the total amount of oily components was low at 33%. In the reference example, the change in viscosity was relatively small under all conditions, including 50°C and low-temperature-high-temperature cycles, and the viscosity stability was evaluated as A. In contrast, in Comparative Examples 1 to 3, in which the total content of oily components was 10% by mass or more relative to the total amount of cosmetic product, the content of polar oil relative to the total amount of oily components was 50% by mass or more, and component (B) was not included, the change in viscosity at high temperatures was large, and creaming occurred in Comparative Example 3. On the other hand, in the example containing component (B), the viscosity remained stable under all conditions, including 50°C and low-temperature-high-temperature cycles, even when the content of polar oil was 50% or more.

Claims

1. An oil-in-water emulsion cosmetic comprising (A) an α-hydroxy acid or a salt thereof, (B) a carboxyvinyl polymer, (C) an oily component, and (D) water, wherein the content of component (A) is 1% by mass or more of the total amount of the cosmetic, component (C) contains (c-1) a polar oil, the content of component (c-1) is 50% by mass or more of the total amount of component (C), and the pH of the cosmetic at 30°C is 5.0 or less.

2. The oil-in-water emulsion cosmetic composition according to claim 1, further comprising an agent selected from the group consisting of (E)(e-1) tranexamic acid and (e-2) alkoxysalicylic acid.

3. The oil-in-water emulsion cosmetic according to claim 1 or 2, wherein the content of component (C) is 10 to 40% by mass with respect to the total amount of the cosmetic.

4. The oil-in-water emulsion cosmetic composition according to claim 1 or 2, wherein component (c-1) contains an ultraviolet absorber.

5. The oil-in-water emulsion cosmetic according to claim 4, wherein the content of the ultraviolet absorber is 1% by mass or more with respect to the total amount of the cosmetic.

6. (F) The oil-in-water emulsion cosmetic composition according to claim 1 or 2, further comprising a nonionic surfactant.

7. (G) The oil-in-water emulsion cosmetic composition according to claim 1 or 2, further comprising a higher alcohol.

8. An oil-in-water emulsion cosmetic according to claim 1 or 2, which is a sunscreen cosmetic.

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