Oil-in-water type emulsion cosmetic

Abstract

[Problem] The purpose of the present invention is to provide an oil-in-water type emulsion cosmetic in which a vitamin A derivative can be stably blended in the presence of a coloring material powder and that has excellent emulsion stability therein. [Solution] This oil-in-water type emulsion cosmetic contains (A) a vitamin A derivative, (B) a coloring material powder, (C) a water-soluble thickener, and (D) a polar oil, the oil-in-water type emulsion cosmetic being characterized in that: the component (B) is blended in an aqueous phase; the component (C) includes at least one selected from (c1) an acrylic acid-alkyl methacrylate polymer, (c2) a hydrophobically modified alkyl cellulose, and (c3) a polymer of a (meth)acryloyldimethyltaurate and a (meth)acrylic acid polyoxyethylene alkyl ether; the blending amount of the component (C) is 0.2 mass% or greater relative to the total amount of the cosmetic; and the blending amount of the component (D) is 17-30 mass% relative to the total amount of the cosmetic.

Description

Oil-in-water emulsion cosmetics

[0001] The present invention relates to an oil-in-water emulsion cosmetic that can stably incorporate a vitamin A derivative in the presence of a colorant powder and that also has excellent emulsion stability.

[0002] Vitamin A compounds (=retinol compounds), such as vitamin A and vitamin A acetate, have long been known as effective ingredients for preventing and treating skin keratosis, abnormal dryness, pigmentation, and the like, as well as preventing and repairing skin aging, and are widely used in cosmetics for treating acne, promoting skin turnover, and the like. However, vitamin A compounds are extremely unstable and are easily degraded by numerous factors, including light, air, heat, and metal ions. For this reason, it is difficult to stably incorporate vitamin A compounds into oil-in-water emulsion cosmetics, and the problem is how to prevent the degradation of vitamin A compounds and maintain their activity.

[0003] For example, Patent Document 1 proposes improving the emulsion stability of an oil-in-water emulsion cosmetic while stably maintaining vitamin A by configuring the internal oil phase from a first oil phase containing a powder and a second oil phase containing vitamin A. However, in Patent Document 1, the first and second oil phases are emulsified in the aqueous phase using a nonionic surfactant, but nonionic surfactants tend to deteriorate the stability of vitamin A derivatives, particularly vitamin A acetate. Furthermore, while blending a certain amount of polar oil is effective in maintaining the stability of vitamin A derivatives, the emulsification state of the base tends to deteriorate as the amount of polar oil increases.

[0004] Meanwhile, in anticipation of the effects of vitamin A, attempts have been made to incorporate vitamin A into not only skin care cosmetics but also makeup cosmetics. However, when an oil-in-water emulsion cosmetic containing vitamin A is further compounded with powder components such as pigments and ultraviolet absorbers required for makeup cosmetics, the emulsified state of the cosmetic becomes unstable.

[0005] Therefore, when an oil-in-water emulsion cosmetic containing a vitamin A derivative further contains a coloring material powder or an ultraviolet absorber, there have been many challenges in achieving both emulsion stability and vitamin A derivative stability.

[0006] International Publication No. 2021 / 221149

[0007] An object of the present invention is to provide an oil-in-water emulsion cosmetic that contains both a vitamin A derivative and a colorant powder, and that has excellent stability of the vitamin A derivative and excellent emulsion stability of the cosmetic.

[0008] As a result of extensive research into solving the above-mentioned problems, the present inventors have discovered that, in an oil-in-water emulsion cosmetic containing a vitamin A derivative in the internal oil phase, by blending a colorant powder and a specific water-soluble thickener in the external aqueous phase and blending a certain amount of polar oil in the internal oil phase, it is possible to obtain an oil-in-water emulsion cosmetic that stably maintains the vitamin A derivative and also has excellent emulsion stability, even when both the vitamin A derivative and the colorant powder are blended, and have thus completed the present invention.

[0009] That is, the present invention provides an oil-in-water emulsion cosmetic containing (A) a vitamin A derivative, (B) a coloring material powder, (C) a water-soluble thickener, and (D) a polar oil, characterized in that the (B) coloring material powder is blended into an aqueous phase, the (C) water-soluble thickener comprises at least one selected from (c1) an acrylic acid / alkyl methacrylate polymer, (c2) a hydrophobically modified alkyl cellulose, and (c3) a polymer of (meth)acryloyldimethyl taurate and a polyoxyethylene alkyl ether (meth)acrylate, the blending amount of the (C) water-soluble thickener is 0.2% by mass or more with respect to the total amount of the cosmetic, and the blending amount of the (D) polar oil is 17 to 30% by mass with respect to the total amount of the cosmetic.

[0010] By adopting the above-described configuration, the oil-in-water emulsion cosmetic according to the present invention can maintain the stability of the vitamin A derivative and prevent a decrease in emulsion stability even when a coloring material powder is blended therein. This makes it possible to realize a makeup cosmetic containing a vitamin A derivative. Furthermore, since sufficient emulsification is possible according to the present invention, it is possible to realize an oil-in-water emulsion cosmetic that is substantially free of nonionic surfactants.

[0011] The oil-in-water emulsion cosmetic of the present invention is characterized by containing (A) a vitamin A derivative, (B) a coloring material powder, (C) a water-soluble thickener, and (D) a polar oil. Each component constituting the oil-in-water emulsion cosmetic of the present invention will be described in detail below.

[0012] <(A) Vitamin A Derivative> The (A) vitamin A derivative (hereinafter sometimes simply referred to as "component (A)") used in the present invention is also called a retinoid, and refers to a substance derived from vitamin A (retinol) and similar in chemical structure and function to vitamin A. Examples include vitamin A aldehyde (retinal), vitamin A acid (retinoic acid), vitamin A fatty acid esters, and salts thereof. Examples of vitamin A fatty acid esters include vitamin A acetate (retinol acetate), vitamin A palmitate (retinol palmitate), vitamin A propionate (retinol propionate), and retinol linoleate. Examples of salts include alkali metal salts (e.g., sodium salt, potassium salt, and lithium salt), alkaline earth metal salts (e.g., calcium salt and magnesium salt), ammonium salt, and organic amine salts (e.g., monoethanolamine salt, diethanolamine salt, and triethanolamine salt). In the present invention, from the viewpoint of application to the skin, vitamin A acetate (retinol acetate) is preferably used. As component (A) of the present invention, one or more of the above vitamin A derivatives can be used.

[0013] The amount of component (A) in the cosmetic of the present invention is not particularly limited, as long as it is an amount typically blended in a cosmetic in anticipation of the effects of a vitamin A derivative. For example, the lower limit of the blending amount is preferably 0.001% by mass or more, and more preferably 0.1% by mass or more, relative to the total amount of the cosmetic. For example, the upper limit is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. Therefore, examples of blending amount ranges include 0.001 to 0.5% by mass and 0.1 to 0.3% by mass.

[0014] <(B) Colorant Powder> The (B) colorant powder (hereinafter sometimes simply referred to as "component (B)") used in the present invention is not particularly limited as long as it is a powder that can be blended into cosmetics, topical skin preparations, etc. for the purpose of imparting a desired color to the skin and adjusting the gloss and feel during use. Examples include inorganic powders and organic powders, and the powder surface may be untreated or may have been subjected to a hydrophobic treatment.

[0015] Examples of inorganic powders include extender pigments (e.g., talc, kaolin, sericite, muscovite, synthetic mica, synthetic phlogopite, phlogopite, lepidolite, biotite, lepidolite, vermiculite, magnesium carbonate, calcium carbonate, diatomaceous earth, magnesium silicate, calcium silicate, aluminum silicate, barium silicate, strontium silicate, metal tungstate, silica, hydroxyapatite, zeolite, boron nitride, and ceramic powder); hydrophilic colorants, for example, inorganic white pigments (e.g., pigment-grade titanium oxide and pigment-grade zinc oxide); inorganic red pigments (e.g., iron titanate); inorganic Examples of the pigment include purple pigments (e.g., mango violet and cobalt violet); inorganic green pigments (e.g., chromium oxide, chromium hydroxide, and cobalt titanate); inorganic blue pigments (e.g., ultramarine and iron blue); pearl pigments (e.g., titanium oxide-coated mica, titanium oxide-coated bismuth oxychloride, titanium oxide-coated talc, colored titanium oxide-coated mica, bismuth oxychloride, and fish scale leaf); red iron oxide (red iron oxide), yellow iron oxide, black iron oxide, and carbon black; and metal powder pigments (e.g., aluminum powder and copper powder).

[0016] Examples of organic powders include organic pigments (e.g., Red No. 104, Red No. 202, Red No. 226, Yellow No. 4, Yellow No. 5, Blue No. 1, and Black No. 401); lake pigments (e.g., zirconium lakes, barium lakes, or aluminum lakes such as Red No. 3, Red No. 104, Red No. 106, Red No. 227, Red No. 230, Red No. 401, Red No. 505, Orange No. 205, Yellow No. 4, Yellow No. 5, Yellow No. 202, Yellow No. 203, Green No. 3, and Blue No. 1); and the like.

[0017] One or more of the above powders can be used as component (B) of the present invention. Among these, pigment-grade iron oxides such as yellow iron oxide, red iron oxide, and black iron oxide, and pigment-grade titanium oxide are preferably used as component (B) of the present invention. Here, "pigment-grade" refers to an average particle size of 100 nm to 1 μm. The average particle size of the pigment can be measured using a transmission electron microscope or laser scattering / diffraction method.

[0018] The colorant powder (B) of the present invention preferably has a hydrophobic surface. Examples of methods for hydrophobicizing the powder surface include silica treatment using silica, hydrated silica, or the like; alkyldextrin treatment using dextrin palmitate, or the like; treatment with a quaternary ammonium salt-type cationic surfactant such as distearyldimonium chloride (distearyldimethylammonium chloride); silicone treatment using methylhydrogenpolysiloxane, methylpolysiloxane, or the like; fluorine treatment using perfluoroalkyl phosphate esters, perfluoroalcohols, or the like; amino acid treatment using N-acylglutamic acid, or the like; lecithin treatment; metal soap treatment such as aluminum stearate treatment, magnesium stearate treatment, and magnesium isostearate treatment; fatty acid treatment; inorganic compound treatment; and alkyl phosphate ester treatment. These hydrophobic treatments can be carried out according to conventional methods. Metal soap treatment is preferred as the hydrophobic treatment used in the cosmetics of the present invention.

[0019] The oil-in-water emulsion cosmetic according to the present invention is characterized in that (B) a coloring material powder is blended in the aqueous phase.

[0020] The amount of component (B) in the cosmetic of the present invention is not particularly limited as long as it is an amount that imparts the desired color to the skin, but it is usually blended in at least 1% by mass, typically at least 3% by mass, relative to the total amount of the cosmetic. The upper limit of the blending amount of component (B) can be, for example, 20% by mass or less, or 15% by mass or less, relative to the total amount of the cosmetic. Examples of blending amount ranges include 1 to 20% by mass, 3 to 15% by mass, etc., relative to the total amount of the cosmetic.

[0021] <(C) Water-Soluble Thickener> The (C) water-soluble thickener (hereinafter, may be simply referred to as "component (C)") used in the present invention is one or more selected from (c1) an acrylic acid / alkyl methacrylate polymer, (c2) a hydrophobically modified alkyl cellulose, and (c3) a polymer of (meth)acryloyldimethyltaurate and polyoxyethylene alkyl ether (meth)acrylate.

[0022] The acrylic acid / alkyl methacrylate polymer (c1) that can be used in the present invention is preferably one designated as "(acrylates / alkyl acrylate (C10-30)) crosspolymer" in the cosmetic product name ("acrylic acid / alkyl methacrylate copolymer" in the quasi-drug product name). An example of a commercially available product of this type is PEMULEN (registered trademark) TR-2 (manufactured by Lubrizol).

[0023] The hydrophobically modified alkyl cellulose (c2) that can be used in the present invention is preferably an alkyl cellulose that has been hydrophobically modified with an alkyl group having 14 to 22 carbon atoms. More specifically, it is a compound in which a long-chain alkyl group, which is a hydrophobic group, has been introduced into a water-soluble cellulose ether derivative, and is preferably one represented by the following general formula (I): [wherein R may be the same or different and is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a -[CH ２ CH (CH ３ ) O] ｍ -H (wherein m is an integer of 1 to 5, preferably an integer of 1 to 3), a group -CH ２ CH ２ OH and the group —CH ２ CH(OH)CH ２ OR' (wherein R' is an alkyl group having 14 to 22 carbon atoms), ２ CH(OH)CH ２ OR' is always included. A is a group -(CH ２ ) ｑ - (q is an integer of 1 to 3, preferably 1), and n is an integer of 100 to 10,000, preferably an integer of 500 to 5,000.

[0024] The method for producing the hydrophobically modified alkyl cellulose of the formula (I) generally involves the step of: 1) preparing a base water-soluble cellulose ether derivative, specifically, methyl cellulose (wherein R is a hydrogen atom or a methyl group), ethyl cellulose (wherein R is a hydrogen atom or an ethyl group), propyl cellulose (wherein R is a hydrogen atom or a propyl group), butyl cellulose (wherein R is a hydrogen atom or a butyl group), hydroxypropyl cellulose (wherein R is a hydrogen atom or a hydroxypropyl group (group -[CH ２ CH (CH ３ ) O] ｍ —H (wherein m is an integer of 1 to 5, preferably an integer of 1 to 3))], hydroxypropyl methylcellulose (wherein R is a hydrogen atom, a methyl group, or a hydroxypropyl group (group —[CH ２ CH (CH ３ ) O] ｍ -H (wherein m is an integer of 1 to 5, preferably an integer of 1 to 3))] or the like, with a compound for introducing a long-chain alkyl group having 14 to 22 carbon atoms, specifically a long-chain alkyl glycidyl ether of the following formula (II), in the presence of an alkali catalyst, to obtain the above-mentioned compound. [R' is an alkyl group having 14 to 22 carbon atoms.]

[0025] The group —CH introduced into the hydrophobically modified alkyl cellulose (c2) of the present invention ２ CH(OH)CH ２ The content of OR' is preferably about 0.1 to 5.0% by mass based on the total amount of (c2) hydrophobically modified alkyl cellulose. To achieve this content, the molar ratio of the water-soluble cellulose ester derivative and the long-chain alkyl glycidyl ether in the reaction, the reaction time, the type of alkali catalyst, and other factors may be appropriately selected. After the reaction, the reaction product may be subjected to purification steps such as neutralization, filtration, washing, drying, and sieving.

[0026] Among the above water-soluble cellulose ether derivatives, it is particularly preferable to select hydroxypropylmethylcellulose (wherein R in formula (I) is a hydrogen atom, a methyl group, a -[CH ２ CH (CH ３ ) O] ｍ -H and the group -CH ２ CH(OH)CH２ OR', and q of the group A is 1, and A is a methylene group. Furthermore, R' in the long-chain alkyl glycidyl ether of formula (II) is an alkyl group having 14 to 22 carbon atoms, preferably an alkyl group having 14 to 20 carbon atoms, and more preferably a stearyl group having 18 carbon atoms (-C １８ H ３７ If the alkyl group R′ has less than 14 carbon atoms or 23 or more carbon atoms, the emulsion stability of the resulting hydrophobically modified alkyl cellulose (c2) may become insufficient.

[0027] The weight average molecular weight of the (c2) hydrophobically modified alkyl cellulose is preferably 100,000 to 1,000,000, more preferably 300,000 to 800,000, and even more preferably 550,000 to 750,000.

[0028] The hydrophobically modified alkyl cellulose (c2) that can be used in the cosmetic of the present invention is preferably stearoxyhydroxypropyl methylcellulose (cosmetic labeling name: hydroxypropyl methylcellulose stearoxy ether), in which the hydrophobic group R' in formula (II) is a stearyl group. Commercially available products include Sangelose 90L, 90M, 90H, 60L, 60M, and 60H (all manufactured by Daido Chemical Industry Co., Ltd.).

[0029] As the (c3) polymer of (meth)acryloyldimethyltaurate and polyoxyethylene alkyl ether (meth)acrylate that can be used in the present invention, (ammonium acryloyldimethyltaurate / beheneth-25 methacrylate) crosspolymer is preferably used. An example of a commercially available product of this crosspolymer is Aristoflex (registered trademark) HMB (manufactured by Clariant Japan).

[0030] As component (C) of the present invention, (c1), (c2), and (c3) may be used alone, or two or more selected from (c1), (c2), and (c3) may be used in combination. From the viewpoint of obtaining sufficient emulsion stability, the blending amount of component (C) in the cosmetic of the present invention is 0.2% by mass or more based on the total amount of the cosmetic. For example, the blending amount range is preferably 0.2 to 1.0% by mass, more preferably 0.2 to 0.8% by mass, and even more preferably 0.2 to 0.6% by mass. If the blending amount is less than 0.2% by mass, sufficient emulsion stability may not be obtained, and if the blending amount exceeds 1.0% by mass, the feel during use may be poor.

[0031] The cosmetic of the present invention may contain a water-soluble (hydrophilic) thickener other than the component (C). When a water-soluble thickener other than the component (C) is contained, the proportion of the component (C) relative to the total amount of water-soluble thickeners contained in the cosmetic is preferably 20% by mass or more, more preferably 20 to 80% by mass, even more preferably 20 to 60% by mass, and still more preferably 20 to 40% by mass.

[0032] <(D) Polar Oil> The polar oil (D) used in the present invention (hereinafter, sometimes simply referred to as "component (D)") is an ester oil and an oil-soluble UV absorber having an IOB value of 0.05 to 0.80. Here, the IOB value means the ratio of the inorganic value (IV) to the organic value (OV) in the organic conceptual diagram, i.e., "inorganic value (IV) / organic value (OV)." For details of the organic conceptual diagram, see, for example, "Organic Conceptual Diagram - Fundamentals and Applications" (by Yoshio Koda, Sankyo Publishing, 1984).

[0033] Component (D) of the present invention is not particularly limited, but examples thereof include isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, cholesteryl hydroxystearate, ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glyceryl diisostearate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, tetraethyl acrylate, methyl acrylate, methyl acrylate copolymer, methyl acrylate copolymer, methyl acrylate copolymer, methyl acrylate copolymer, methyl acrylate copolymer Examples of suitable oil-soluble UV absorbers include pentaerythrityl hexanoate, glyceryl tri-2-ethylhexanoate, cetyl 2-ethylhexanoate, ethylhexyl palmitate, glyceryl trimyristate, tri-2-heptylundecanoic acid glyceride, castor oil fatty acid methyl esters, oleyl oleate, acetoglyceride, 2-heptylundecyl palmitate, diisobutyl adipate, diheptylundecyl adipate, ethyl laurate, diethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, di-2-hexyldecyl adipate, diisopropyl sebacate, tripropylene glycol dipivalate (PPG-3 dipivalate), diethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, triethyl citrate, and oil-soluble UV absorbers.

[0034] The cosmetic of the present invention can be imparted with an ultraviolet protection effect by incorporating an oil-soluble ultraviolet absorber as part or all of the polar oil (D). The oil-soluble ultraviolet absorber to be incorporated into the cosmetic of the present invention can be selected from those conventionally used in cosmetics.

[0035] Examples of the oil-soluble UV absorber include organic UV absorbers such as cinnamic acid-based UV absorbers, β,β-diphenylacrylate-based UV absorbers, benzophenone-based UV absorbers, benzalmalonate-based UV absorbers, dibenzoylmethane-based UV absorbers, triazine-based UV absorbers, benzoic acid-based UV absorbers, phenylbenzotriazole-based UV absorbers, phenylbenzimidazole-based UV absorbers, and salicylic acid-based UV absorbers. More specific examples include ethylhexyl methoxycinnamate, octocrylene, 2-hydroxy-4-methoxybenzophenone, dimethicodiethyl benzalmalonate (polysilicone-15), 4-tert-butyl-4'-methoxydibenzoylmethane (t-butylmethoxydibenzoylmethane), bisethylhexyloxyphenol methoxyphenyl triazine, ethylhexyl triazone, diethylaminohydroxybenzoyl hexyl benzoate, methylenebisbenzotriazolyltetramethylbutylphenol, phenylbenzimidazole sulfonic acid, homosalate, and ethylhexyl salicylate.

[0036] The component (D) of the present invention can be one or a combination of two or more selected from the above polar oils. From the viewpoint of the stability of the vitamin A derivative (A), the blending amount of component (D) in the cosmetic of the present invention is preferably 17 to 30 mass% of the total amount of the cosmetic, and more preferably 18 to 28 mass%. If the blending amount is less than 17 mass%, the stability of the vitamin A derivative (A) cannot be sufficiently obtained, and if the blending amount exceeds 30 mass%, the emulsion stability of the cosmetic may be deteriorated.

[0037] The oil-in-water emulsion cosmetic of the present invention does not need to contain silicone oil because silicone oil does not contribute to maintaining the stability of the vitamin A derivative (A). If silicone oil is added, its amount is preferably less than 1% by mass of the total amount of the cosmetic, from the viewpoints of both drug stability and emulsion stability of the base.

[0038] According to the present invention, an oil-in-water emulsion cosmetic having excellent emulsion stability can be obtained without using a nonionic surfactant. When a nonionic surfactant is incorporated into the oil-in-water emulsion cosmetic of the present invention, the ratio of the total amount of nonionic surfactants to the total amount of water-soluble thickeners (the total amount of component (C) of the present invention and other water-soluble (hydrophilic) thickeners) (total amount of nonionic surfactants / total amount of water-soluble thickeners) is preferably 0.3 or less in mass ratio. From the viewpoint of the stability of the vitamin A derivative (A), it is preferable that the cosmetic of the present invention does not substantially incorporate a nonionic surfactant. Therefore, the oil-in-water emulsion cosmetic of the present invention also includes an embodiment in which the nonionic surfactant is present in an amount of 0.2 mass% or less or 0.1 mass% or less of the total amount of the cosmetic, and an embodiment in which no nonionic surfactant is present.

[0039] The preferred viscosity of the cosmetic of the present invention varies depending on the application, but from the viewpoint of obtaining stability of the vitamin A derivative (A) and emulsion stability of the base, the viscosity range is preferably 50,000 to 150,000 mPa s, and more preferably 70,000 to 120,000 mPa s. Viscosity in this specification is a value measured at 30°C using a B-type viscometer.

[0040] In addition to the above components (A) to (D), the oil-in-water emulsion cosmetic of the present invention may contain other components commonly used in cosmetics, provided that the effects of the present invention are not impaired. For example, water-soluble (hydrophilic) thickeners other than component (C), oils other than component (D), aqueous solvents, humectants, drugs, antioxidants, as well as neutralizing agents, chelating agents, preservatives, powders other than component (B), fragrances, coloring materials other than component (B), pigments, etc. may be appropriately blended as needed.

[0041] Examples of water-soluble (hydrophilic) thickeners other than component (C) include plant-based polymers such as gum arabic, tragacanth, galactan, carob gum, guar gum, karaya gum, carrageenan, xanthan gum, pectin, agar, quince seed (marmelo), and algae colloid (brown algae extract); microbial-based polymers such as gellan gum, dextran, succinoglycan, and pullulan; animal-based polymers such as collagen, casein, albumin, and gelatin; starch-based polymers such as starch (rice, corn, potato, and wheat), carboxymethyl starch, and methylhydroxypropyl starch; cellulose-based polymers such as methylcellulose, nitrocellulose, ethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, sodium cellulose sulfate, hydroxypropylcellulose, sodium carboxymethylcellulose, crystalline cellulose, and cellulose powder; and sodium alginate. vinyl polymers such as polyvinyl methyl ether and carboxyvinyl polymers; acrylic polymers such as polyoxyethylene polymers, polyoxyethylene polyoxypropylene copolymer polymers, polyethyl acrylate and polyacrylamide; inorganic water-soluble polymers such as polyethyleneimine, cationic polymers, bentonite, magnesium aluminum silicate, laponite, hectorite and silicic anhydride; PEG-240 / decyltetradeceth-20 / hexamethylene diisocyanate copolymer, (dimethylacrylamide / sodium acryloyldimethyltaurate) crosspolymer, (sodium acrylate / acryloyldimethyltaurate) copolymer, (alkyl acrylate / steareth-20 methacrylate) copolymer, (ammonium acryloyldimethyltaurate / vinylpyrrolidone) copolymer, and the like.

[0042] The oil component other than component (D) is not particularly limited as long as it is an oil component that is normally blended in cosmetics, and examples thereof include hydrocarbon oils, higher alcohols, ester oils, fatty acids, fats and oils, and waxes.

[0043] Examples of aqueous solvents include water (purified water, ion-exchanged water, tap water, etc.), lower alcohols (ethanol, etc.), and mixtures thereof.

[0044] Examples of moisturizing agents include polyoxyalkylene-polyoxyethylene copolymer dialkyl ether, 1,3-butylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, glycerin, diglycerin, xylitol, maltitol, maltose, and D-mannite.

[0045] Examples of the drug include ascorbic acid (vitamin C), tranexamic acid, kojic acid, ellagic acid, arbutin, alkoxysalicylic acid, nicotinamide, glycyrrhizinic acid, tocopherol, and salts or derivatives thereof (e.g., sodium L-ascorbate, magnesium L-ascorbate, L-ascorbic acid glucoside, 2-O-ethyl-L-ascorbic acid, 3-O-ethyl-L-ascorbic acid, sodium 4-methoxysalicylate, potassium 4-methoxysalicylate, dipotassium glycyrrhizinate, stearyl glycyrrhizinate, and tocopherol acetate).

[0046] The antioxidant is preferably an oil-soluble one, and examples thereof include dibutylhydroxytoluene (BHT), butylhydroxyanisole (BHA), α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol, nordihydroguaiaretic acid (NDGA), propyl gallate, and fatty acid esters of vitamin C, or sorbic acid.

[0047] The oil-in-water emulsion cosmetic of the present invention can be produced according to conventional methods, for example, by mixing components (A) and (D) with other oily components to prepare an oil phase part, and then mixing the oil phase part with an aqueous phase part prepared separately by mixing components (B) and (C) with other aqueous components, followed by emulsification using a homomixer or the like.

[0048] The form of the oil-in-water emulsion cosmetic of the present invention is not particularly limited, and any form that has conventionally been used in cosmetics, such as lotion, emulsion, cream, gel, or essence (serum), can be widely applied.

[0049] The oil-in-water emulsion cosmetic of the present invention can be blended with a colorant powder and an ultraviolet absorber, and is therefore suitable for use as a makeup cosmetic containing a vitamin A derivative, such as a foundation, concealer, eye shadow, eyeliner, mascara, blush, makeup base, and sunscreen.

[0050] The present invention will be described in further detail below with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, the blending amount is expressed as mass % relative to the system in which the component is blended. Before describing each example in detail, the evaluation methods used will be described.

[0051] 1. Emulsion stability Each cosmetic preparation (sample) was stored for one month at 50°C, and the appearance after storage was visually inspected for the presence or absence of separation. Those in which no change in appearance (separation) was observed were rated as "stable," and those in which even slight separation was observed were rated as "separated."

[0052] 2. Stability of Vitamin A Derivatives Each cosmetic sample contained in a glass screw tube was protected from light with aluminum foil and stored at 50°C for one month, and the remaining percentage (%) of vitamin A derivative compared to before storage was determined using high performance liquid chromatography. High performance liquid chromatography was performed under the following conditions: Column: C18 column (Shiseido Co., Ltd.) Detection: UV 310 nm Mobile phase: 72% methanol / 10% acetonitrile / 18% ion-exchanged water / 0.5% acetic acid

[0053] <Evaluation criteria> A: Residual rate is 85% or more B: Residual rate is 75% or more but less than 85% C: Residual rate is 65% or more but less than 75% D: Residual rate is less than 65%

[0054] Oil-in-water emulsion cosmetics having the compositions shown in Tables 1 and 2 below were prepared and evaluated according to the evaluation methods described above. The results are also shown in the tables.

[0055]

[0056] As shown in Comparative Example 1, when the total blending amount of (D) polar oil was as low as 5.95% by mass, emulsion stability was obtained, but stability of (A) vitamin A derivative was not obtained. As the total blending amount of (D) polar oil increased to 14%, 16%, 20%, and 23% by mass, the stability of (A) vitamin A derivative improved, but the emulsion stability of the cosmetic composition deteriorated (Comparative Examples 2 to 5). These results demonstrate that in the oil-in-water emulsion system containing (B) colorant powder of the present invention, a total of more than 16% by mass of (D) polar oil is required to obtain stability of component (A). Furthermore, a comparison of Comparative Example 4 with Example 1 in Table 2 (both containing a total of 20% by mass of (D) polar oil), and a comparison of Comparative Example 5 with Example 2 in Table 2 (both containing a total of 23% by mass of (D) polar oil) show that even when the total amount of water-soluble thickener is the same, it is necessary to incorporate a certain amount or more of the (C) water-soluble thickener of the present invention ((acrylates / C10-30 alkyl acrylate crosspolymer, stearoxyhydroxypropyl methylcellulose) in order to obtain emulsion stability. Furthermore, in Comparative Example 7, in which part of the (D) polar oil was replaced with hydrocarbon oil, the (A) vitamin A derivative could not be stably maintained.

[0057]

[0058] On the other hand, in the cosmetics of Examples 1 to 6, in which the blending amount of the water-soluble thickener (C) of the present invention was 0.3 mass % and the total blending amount of the polar oil (D) was 20 mass % or more, sufficient emulsion stability was obtained, and it was shown that the vitamin A derivative (A) was stably maintained.

Claims

1. An oil-in-water emulsion cosmetic comprising: (A) a vitamin A derivative; (B) a coloring powder; (C) a water-soluble thickener; and (D) a polar oil; wherein the (B) component is blended in an aqueous phase; the (C) component comprises at least one selected from the group consisting of (c1) an acrylic acid / alkyl methacrylate polymer, (c2) a hydrophobically modified alkyl cellulose, and (c3) a polymer of (meth)acryloyldimethyltaurate and polyoxyethylene alkyl ether (meth)acrylate; the blending amount of the (C) component is 0.2% by mass or more based on the total amount of the cosmetic; and the blending amount of the (D) component is 17 to 30% by mass based on the total amount of the cosmetic.

2. The cosmetic preparation according to claim 1, wherein the component (B) is a powder that has been surface-hydrophobized.

3. The cosmetic preparation according to claim 1, wherein the component (C) is at least one selected from (c1) an acrylic acid / methacrylic acid alkyl polymer and (c2) a hydrophobically modified alkyl cellulose.

4. The cosmetic preparation according to claim 1, wherein the (c1) acrylic acid / alkyl methacrylate polymer is an (acrylates / alkyl acrylate (C10-30)) crosspolymer, the (c2) hydrophobically modified alkyl cellulose is stearoxyhydroxypropyl cellulose, and the (c3) polymer of (meth)acryloyldimethyltaurate and polyoxyethylene alkyl ether (meth)acrylate is an (ammonium acryloyldimethyltaurate / beheneth-25 methacrylate) crosspolymer.

5. The cosmetic according to claim 1, wherein when the cosmetic contains a nonionic surfactant, the amount of the nonionic surfactant is 0.2 mass% or less based on the total amount of the cosmetic.

6. The cosmetic according to claim 1, wherein the viscosity of the cosmetic is within the range of 50,000 to 150,000 mPa·s.

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