Oil-based emulsions in water

Abstract

The oil-in-water emulsion of the present invention comprises: (a) at least one acid selected from the group consisting of alpha hydroxy acids (AHA), beta hydroxy acids (BHA), and polyhydroxyalkanoic acids (PHAs); (b) batyl alcohol; (c) at least one thickener selected from the group consisting of cellulose-based thickeners having an alkyl group with 10 to 30 carbon atoms, and polysaccharide thickeners containing glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides; and (d) an oil.

Description

[Technical Field]

[0001] The present invention relates to an oil-in-water emulsion. [Background technology]

[0002] Polishing serum is a type of peeling serum that contains a peeling agent such as glycolic acid to remove dead cells from the skin surface and smooth the skin surface. Demand for peeling serums is currently increasing, especially in Asia. However, currently available products have the problem that the peeling agent leaves a sticky residue on the skin. Therefore, formulating a peeling agent is difficult, especially for texture reasons.

[0003] On the other hand, since oils generally have the effect of reducing sticky residues on the skin, emulsion-type peeling serums can smooth the skin without leaving sticky residues. However, peeling agents act as strong electrolytes, causing emulsions to rapidly collapse, making it difficult to create stable emulsions containing peeling agents. In addition, because the pH range in which peeling agents exert their peeling effect is usually low, below 5.5, some emulsifiers or thickeners that stabilize emulsions may not function well under such low pH conditions.

[0004] An example of an emulsion-type composition is the skin care composition described in WO2015013197A1, which is an oil-in-water emulsion having an aqueous phase and an oil phase, wherein the aqueous phase contains more than about 0.5% of an acid in salt form, and the oil-in-water emulsion further contains a gum, and the chemical state and physical uniformity of the composition remain substantially unchanged even after exposure to a temperature of about 50°C for 14 days.

[0005] However, there is a need to provide new oil-in-water emulsions containing acids and stable oil-in-water emulsions containing acids that have a peeling effect and have improved properties in terms of texture and stability. Summary of the Invention

[0006] The present inventors have demonstrated that the use of at least one thickener selected from the group consisting of (b) batyl alcohol, and (c) cellulose-based thickeners having an alkyl group with 10 to 30 carbon atoms, and polysaccharide thickeners containing glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides, in an oil-in-water emulsion containing an acid and an oil meets expectations even at low pH (for example, 5.5 or less).

[0007] Therefore, the present invention relates to an oil-in-water emulsion comprising: (a) at least one acid selected from the group consisting of alpha hydroxy acids (AHA), beta hydroxy acids (BHA), and polyhydroxyalkanoic acids (PHAs); (b) batyl alcohol; (c) at least one thickener selected from the group consisting of cellulose-based thickeners having an alkyl group with 10 to 30 carbon atoms and polysaccharide thickeners containing glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides; and (d) an oil.

[0008] In a specific embodiment, in the oil-in-water emulsion, component (a) comprises glycolic acid.

[0009] In a specific embodiment, the oil-in-water emulsion contains 0.004% by mass or more of component (a).

[0010] In certain embodiments, the pH of the oil-in-water emulsion is 5.5 or less.

[0011] In certain embodiments, the oil-in-water emulsion further comprises an emulsifier.

[0012] In a specific embodiment, in the oil-in-water emulsion, the emulsifier other than component (b) is a nonionic emulsifier.

[0013] In certain embodiments, in the oil-in-water emulsion, the non-ionic emulsifier is a polyglycerol fatty acid ester.

[0014] In a specific embodiment, the oil-in-water emulsion further comprises a thickener other than component (c).

[0015] In a specific embodiment, in the oil-in-water emulsion, component (d) comprises dicaprylyl ether and / or squalane.

[0016] In certain embodiments, the oil-in-water emulsion is a polishing serum.

[0017] Furthermore, the present invention also provides a cosmetic method for caring for and / or making up keratinous materials, which comprises applying the oil-in-water emulsion of the present invention to keratinous materials, particularly to the skin. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a stable oil-in-water emulsion that has a peeling effect even at a low pH (for example, 5.5 or less). DETAILED DESCRIPTION OF THE INVENTION

[0019] Preferred embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments.

[0020] The oil-in-water emulsion according to this embodiment contains (a) at least one acid selected from the group consisting of alpha hydroxy acids (AHA), beta hydroxy acids (BHA), and polyhydroxyalkanoic acids (PHAs), (b) batyl alcohol, (c) at least one thickener selected from the group consisting of cellulose-based thickeners having an alkyl group with 10 to 30 carbon atoms, and polysaccharide thickeners containing glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides, and (d) an oil.

[0021] The oil-in-water emulsion of the present invention contains (a) and thus has the effect of smoothing the skin surface (peeling effect), and contains components (b) and (c) and thus has excellent stability even at low pH (for example, 5.5 or less), and further contains an oil agent (component (d)) and thus does not leave sticky residue on the skin, resulting in an excellent feel when used.

[0022] <Component (a)> The oil-in-water emulsion of the present invention contains, as component (a), at least one acid selected from the group consisting of alpha hydroxy acids (AHA), beta hydroxy acids (BHA), polyhydroxyalkanoic acids (PHA), and mixtures thereof. In the oil-in-water emulsion of this embodiment, component (a) functions as a peeling agent.

[0023] Alpha hydroxy acids (α-hydroxy acids; AHAs) include, for example, glycolic acid, lactic acid, mandelic acid, malic acid, tartaric acid, citric acid, and mixtures thereof. Beta hydroxy acids (BHAs) include, for example, salicylic acid and carnitine. Polyhydroxyalkanoic acids (PHAs) include, for example, gluconolactone and lactobionic acid.

[0024] AHA, BHA, and PHA are all weakly acidic and are known to have chemical peeling (skin peeling) properties. AHA is water-soluble and removes dead skin cells from the surface of the skin, promoting skin turnover. BHA is water-soluble and softens and removes sebum and dead skin cells, making it effective against acne and sun damage. PHA is less irritating than AHA and BHA and has high moisturizing power, making it effective against acne, acne scars, rough skin, atopic dermatitis, and other conditions on dry and sensitive skin.

[0025] In the oil-in-water emulsion of the present invention, the acid component (a) may be used alone or in combination of two or more. Component (a) is preferably glycolic acid, lactic acid, salicylic acid, or a combination thereof, with glycolic acid being particularly preferred.

[0026] In certain embodiments, the total content of component (a) in the oil-in-water emulsion of the present invention is, for example, 0.004% by mass or more, 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, or 0.5% by mass or more, and 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass or less, or 5% by mass or less, relative to the total amount of the oil-in-water emulsion. In a preferred embodiment, the total content of component (a) is in the range of 0.1% by mass to 10% by mass, particularly 0.5% by mass to 8% by mass, or 1 to 5% by mass, relative to the total amount of the oil-in-water emulsion.

[0027] In certain embodiments, the total content of component (a) in the oil-in-water emulsion of the present invention is such that the pH of the oil-in-water emulsion is less than 7.0, for example, 6.5 or less, 6.0 or less, 5.5 or less, 5.0 or less, or 4.5 or less, more preferably such that the pH of the oil-in-water emulsion is 5.5 or less, and even more preferably such that the pH of the oil-in-water emulsion is 3.5 to 5.5.

[0028] <(b) Component> The oil-in-water emulsion of the present invention contains batyl alcohol as component (b), which serves as an emulsifying aid and also as a moisturizing agent.

[0029] In certain embodiments, the content of component (b) in the oil-in-water emulsion of the present invention is, for example, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.15% by mass or more, 0.2% by mass or more, or 0.25% by mass or more, and 3.0% by mass or less, 2.5% by mass or less, 2.2% by mass or less, 2.0% by mass or less, 1.5% by mass or less, 1.0% by mass or less, or 0.5% by mass or less, based on the total amount of the oil-in-water emulsion. In particular, the total content of component (b) is in the range of 0.05% by mass to 3.0% by mass, particularly 0.1% by mass to 2.0% by mass or 0.2% by mass to 1.0% by mass, based on the total amount of the oil-in-water emulsion.

[0030] <(c) component> The oil-in-water emulsion of the present invention contains, as component (c), at least one thickener selected from the group consisting of cellulose-based thickeners having an alkyl group with 10 to 30 carbon atoms and polysaccharide thickeners having glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides. In the oil-in-water emulsion of the present invention, component (c) serves as a thickener and, together with component (b), serves to stabilize the oil-in-water emulsion.

[0031] In a specific embodiment, examples of the cellulose-based thickener having an alkyl group having 10 to 30 carbon atoms include hydrophobically modified alkyl cellulose of structural formula (1) described in WO2011-162421A. [ka] (Wherein R1, R2 and R3 may be the same or different and each represent a hydrogen atom, a lower alkyl group, a group: -[CH2CH 2-k (CH3) k O] m H or the group: -CH2CH(OH)CH2OC j H 2j+1 wherein n is an integer of 100 to 10,000, k is an integer of 0 or 1, m is an integer of 1 to 10, and j is an integer of 6 to 26; and the hydrophobically modified alkyl cellulose is a compound selected from the group: -CHCH(OH)CHOC j H 2j+1 wherein the lower alkyl group is a methyl group or an ethyl group, and the hydrophobically modified alkyl cellulose is described, for example, in WO2011 / 162421A.

[0032] In a specific embodiment, the cellulose-based thickener having an alkyl group having 10 to 30 carbon atoms is preferably a cellulose-based thickener derived from hydroxypropyl methylcellulose, such as hydroxypropyl methylcellulose stearoxy ether obtained by reacting hydroxypropyl methylcellulose with stearyl glycidyl ether (e.g., Sangelose 90L, manufactured by Daido Chemical Industry Co., Ltd.). In this case, the hydrophobic group introduced into the hydrophobically modified alkyl cellulose is a stearyl group (-C18 H 37 (number of carbon atoms: 18). In addition to stearyl glycidyl ether, those obtained by reacting cetyl glycidyl ether and decyl glycidyl ether may also be used.

[0033] In a specific embodiment, a polysaccharide thickener containing glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides has a main chain in which, for example, constituent units consisting of glucose, glucuronic acid, glucose, and rhamnose are linearly linked in this order. The polysaccharide thickener (c) may further have a side chain as part of the polysaccharide structure, or may not have a side chain. The side chain may have, for example, at least one constituent monosaccharide selected from the group consisting of rhamnose, fucose, glucose, and mannose. The polysaccharide thickener may have a main chain in which constituent units consisting of glucose, glucuronic acid, glucose, and rhamnose are linearly linked in this order, and may have rhamnose as a side chain. The polysaccharide thickener may have a main chain in which constituent units consisting of glucose, glucuronic acid, glucose, and rhamnose are linearly linked in this order, and may have fucose as a side chain. The polysaccharide thickener may be derived from a microorganism such as a bacterium. In certain embodiments, the polysaccharide thickener comprises at least one selected from the group consisting of diutan gum, welan gum, gellan gum, and combinations thereof. Diutan gum (DIUTAN GUM; INCI: Sphingomonas ferment extract) is a polysaccharide obtained by aerobic fermentation of corn syrup using a microorganism of the genus Alcaligenes.

[0034] In the oil-in-water emulsion according to this embodiment, component (c) may be used singly or in combination. In a specific embodiment, the total content of component (c) is, for example, 0.01% by mass or more, 0.02% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.06% by mass or more, 0.07% by mass or more, or 0.1% by mass or more, relative to the total amount of the oil-in-water emulsion, and is 1.0% by mass or less, 0.8% by mass or less, 0.6% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, or 0.2% by mass or less. In particular, the total content of component (c) is preferably in the range of 0.01% by mass to 1.0% by mass, and particularly in the range of 0.05% by mass to 0.5% by mass, relative to the total amount of the oil-in-water emulsion.

[0035] <(d) component> The oil-in-water emulsion of the present invention contains an oil as component (d). In a specific embodiment, the oil as component (d) is, for example, a liquid oil or a paste oil, and preferably a liquid oil. The liquid oil may be a non-polar liquid oil or a polar liquid oil.

[0036] Liquid oil refers to a non-evaporative oil component that is liquid at room temperature (i.e., in the range of 15 to 25°C) and normal pressure (i.e., 1 atmosphere). Examples of liquid oils include non-volatile hydrocarbon oils, higher alcohols, ester oils, ether oils, and vegetable oils.

[0037] Examples of non-volatile hydrocarbon oils include squalane, liquid paraffin, petrolatum, polybutene, polyisobutene, hydrogenated polyisobutene, hydrogenated polydecene, olefin oligomers, and mixtures thereof.

[0038] The higher alcohol is an aliphatic monoalcohol having 6 or more carbon atoms, and preferably an aliphatic monoalcohol having 12 to 28 carbon atoms. Examples of higher alcohols include octyl alcohol, dodecyl alcohol, oleyl alcohol, octyldodecanol, hexyldecanol, isostearyl alcohol, decyltetradecanol, and mixtures thereof.

[0039] The ester oil is a carboxylic acid ester that is liquid under normal temperature and pressure conditions (for example, 25°C and 1 atmosphere) and does not vaporize, and is preferably a carboxylic acid alkyl ester in which the carboxylic acid or alcohol constituting the ester has 8 to 18 carbon atoms. Examples of ester oils include propylene glycol fatty acid esters such as propylene glycol dicaprylate and propylene glycol dicaprate; fatty acid alkyl esters such as isoamyl laurate, hexyl laurate, ethylhexyl palmitate, isopropyl myristate, 2-octyldodecyl myristate, cetyl 2-ethylhexanoate, isononyl isononanoate, and isotridecyl isononanoate; carbonates such as dicaprylyl carbonate; tri- or higher fatty acid esters of polyglycerin such as polyglyceryl-2 triisostearate, polyglyceryl-2 tetraisostearate, and polyglyceryl-10 decaisostearate; glyceryl tri-2-ethylhexanoate, glyceryl tribehenate, tri(caprylic / capric)glyceryl, and triheptyl glycerin. Examples of suitable glycerin derivatives include glycerin tri-fatty acid esters (also known as triglyceride oils) such as tanoin; benzoic acid derivatives such as diisostearyl malate and C12-15 alkyl benzoate; salicylic acid derivatives such as homosalate and ethylhexyl salicylate; alkyl esters such as coco-caprylate / caprate and coco-caprylate; cinnamic acid derivatives such as octyl methoxycinnamate, isopropyl methoxycinnamate, isoamyl methoxycinnamate, cinnoxate, DEA methoxycinnamate, diisopropyl methylcinnamate, glyceryl ethylhexanoate-dimethoxycinnamate, and di-(2-ethylhexyl)-4'-methoxybenzalmalonate; and beta, beta-diphenylacrylate derivatives such as octocrylene, as well as mixtures thereof.

[0040] An example of the ether oil is dicaprylyl ether.

[0041] Examples of vegetable oils include meadowfoam oil, olive fruit oil, jojoba seed oil, camellia oil, coconut oil, macadamia nut oil, rosehip oil, avocado oil, sunflower seed oil, rice bran oil, castor oil, almond oil, and mixtures thereof.

[0042] In the oil-in-water emulsion according to this embodiment, the component (d) may be used singly or in combination of two or more types. The component (d) preferably contains dicaprylyl ether and / or squalane.

[0043] In certain embodiments, the total content of component (d) is, for example, 1% by mass or more, 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more, or 7% by mass or more, and 15% by mass or less, 14% by mass or less, 13% by mass or less, 12% by mass or less, 11% by mass or less, 10% by mass or less, 9% by mass or less, or 8% by mass or less, based on the total amount of the oil-in-water emulsion. The total content of component (d) is preferably in the range of 1% to 15% by mass, and particularly in the range of 2% to 10% by mass, based on the total amount of the oil-in-water emulsion.

[0044] <Emulsifier> In certain embodiments, the oil-in-water emulsion may further comprise an emulsifier, such as a non-ionic emulsifier (non-ionic surfactant).

[0045] Examples of nonionic emulsifiers include esters of a fatty acid and polyglycerol (polyglycerol fatty acid esters), esters of a fatty acid and glycerol (glycerol fatty acid esters), and the like, with polyglycerol fatty acid esters being preferred.

[0046] In a specific embodiment, the polyglycerol fatty acid ester is a polyglycerol ester of a fatty acid having 12 to 24 carbon atoms, preferably 16 to 22 carbon atoms, more preferably 18 to 22 carbon atoms, and particularly preferably 18 or 22 carbon atoms. Examples of the constituent fatty acids include palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, isostearic acid, arachidic acid, arachidonic acid, and behenic acid. The fatty acid may be saturated or unsaturated, and is preferably saturated. The number of glycerol units (also referred to as the degree of polymerization of glycerol) contained in the polyglycerol fatty acid ester may be, for example, 2 to 12, preferably 2 to 10, more preferably 2 to 8, and particularly preferably 2 or 6.

[0047] In certain embodiments, the polyglycerol fatty acid ester is selected from the group consisting of, for example, polyglyceryl-2 stearate, polyglyceryl-2 isostearate, polyglyceryl-2 oleate, polyglyceryl-6 stearate, polyglyceryl-6 behenate, and mixtures thereof.

[0048] In certain embodiments, the glycerin fatty acid ester is a glycerin ester of a fatty acid having 12 to 24 carbon atoms, preferably 16 to 22 carbon atoms, more preferably 16 to 20 carbon atoms, and particularly preferably 18 carbon atoms. Examples of fatty acids include palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, arachidic acid, arachidonic acid, and behenic acid. The fatty acid may be saturated or unsaturated, and is preferably saturated. In certain embodiments, the glycerin fatty acid ester is selected from the group consisting of, for example, glyceryl stearate, glyceryl oleate, glyceryl myristate, glyceryl cocoate, glyceryl undecylenate, and mixtures thereof.

[0049] Preferably, all emulsifiers are solid at room temperature (e.g., 25°C). In certain preferred embodiments, the emulsifier is preferably selected from the group consisting of polyglycerol esters of fatty acids having 12 to 24 carbon atoms and having 2 to 12 glycerin units, glycerol esters of fatty acids having 12 to 24 carbon atoms, and mixtures thereof, and more preferably selected from polyglycerol esters of fatty acids having 12 to 24 carbon atoms and having 2 to 12 glycerin units, and mixtures thereof. In certain embodiments, the emulsifier is, for example, polyglyceryl-6 stearate or polyglyceryl-6 behenate. An example of a commercially available product containing a combination of polyglyceryl-6 stearate and polyglyceryl-6 behenate is TEGO CARE PBS 6 (Evonik Operations GmbH).

[0050] In certain embodiments, the emulsifier may be used alone or in combination. In certain embodiments, the total content of the emulsifiers may be, for example, 0.1% by mass or more, 0.2% by mass or more, 0.5% by mass or more, 0.7% by mass or more, 1.0% by mass or more, or 1.2% by mass or more, relative to the total amount of the oil-in-water emulsion, and 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2.5% by mass or less, 2.2% by mass or less, or 2% by mass or less. The total content of the emulsifiers is particularly in the range of 0.5% by mass to 10% by mass, more particularly in the range of 0.5% by mass to 5% by mass, or preferably in the range of 1% by mass to 3% by mass, relative to the total amount of the oil-in-water emulsion.

[0051] <Thickener> In certain embodiments, the oil-in-water emulsion further contains a thickener other than component (c). Examples of thickeners other than component (c) include cellulose-based thickeners other than component (c), polysaccharide thickeners other than component (c), alkyl-modified carboxyvinyl polymers such as (acrylates / C10-30 alkyl acrylate) crosspolymers, acrylic polymers ((meth)acrylic (co)polymers), and mixtures thereof. Preferred examples include polysaccharide thickeners other than component (c), alkyl-modified carboxyvinyl polymers such as (acrylates / C10-30 alkyl acrylate) crosspolymers, acrylic polymers ((meth)acrylic (co)polymers), and mixtures thereof.

[0052] Examples of cellulose-based thickeners other than component (c) include ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl methyl cellulose stearoxy ether, cellulose gum, carboxymethyl cellulose, and mixtures thereof.

[0053] Examples of polysaccharide thickeners other than component (c) include glucomannan, xanthan gum, dehydroxanthan gum, and mixtures thereof.

[0054] The (meth)acrylic polymer may be a polymer obtained by polymerizing one or more monomers selected from the group consisting of (meth)acrylic acid and (meth)acrylic acid esters. The (meth)acrylic acid ester is not particularly limited, and examples thereof include alkyl (meth)acrylic acid esters and alkyl (meth)acrylic acid esters in which the alkyl group is substituted with a substituent such as a hydroxyl group. Preferred are alkyl (meth)acrylic acid esters. Examples of alkyl (meth)acrylic acid esters include alkyl (meth)acrylic acid esters having an alkyl group with 10 to 30 carbon atoms and alkyl (meth)acrylic acid esters having an alkyl group with 1 to 9 carbon atoms. Preferred are alkyl (meth)acrylic acid esters having an alkyl group with 10 to 30 carbon atoms. In a specific embodiment, the (meth)acrylic polymer is a copolymer of at least one monomer selected from the group consisting of (meth)acrylic acid and alkyl (meth)acrylic acid esters having an alkyl group with 1 to 9 carbon atoms, and at least one monomer selected from the group consisting of alkyl (meth)acrylic acid esters having an alkyl group with 10 to 30 carbon atoms.

[0055] In a specific embodiment, the (meth)acrylic polymer includes a carbomer. Commercially available (meth)acrylic polymers can be used, including, for example, Carbopol™ Ultrez 30 Polymer, Carbopol™ Ultrez 10, Carbopol™ ETD 2020, Carbopol™ Ultrez 20 Polymer, and Pemulen TR-1, all manufactured by Lubrizol, Aristoflex™ AVC, and Simulgel™ NS MB, all manufactured by Seppic SA.

[0056] In certain embodiments, the thickeners other than component (c) may be used singly or in combination of two or more. In certain embodiments, the total content of thickeners other than component (c) is, for example, 0.01% by mass or more, 0.02% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.07% by mass or more, 0.10% by mass or more, or 0.12% by mass or more, relative to the total amount of the oil-in-water emulsion, and 1.0% by mass or less, 0.8% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or 0.2% by mass or less. The total content of thickeners other than component (c) is preferably in the range of 0.01% by mass to 1.0% by mass, relative to the total amount of the oil-in-water emulsion.

[0057] In certain embodiments, the total amount of the (c) component and thickeners other than the (c) component is, for example, 0.01% by mass or more, 0.02% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more, and 1.5% by mass or less, 1.0% by mass or less, 0.8% by mass or less, 0.6% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, 0.15% by mass or less, or 0.1% by mass or less, based on the total amount of the oil-in-water emulsion. The total content of the (c) component and thickeners other than the (c) component is preferably in the range of 0.01 to 1.5% by mass based on the total amount of the oil-in-water emulsion.

[0058] <Moisturizer> In a specific embodiment, the oil-in-water emulsion contains a moisturizer other than component (b). By including a moisturizer, it is possible to simultaneously provide a peeling effect and a high moisturizing effect. Examples of moisturizers other than component (b) include polyhydric alcohols having 3 to 5 carbon atoms. The polyhydric alcohol may have, for example, two or three alcoholic hydroxyl groups. Examples of polyhydric alcohols having 3 to 5 carbon atoms include glycerin, 1,3-butylene glycol, pentylene glycol, propanediol, and mixtures thereof.

[0059] In certain embodiments, the moisturizers other than component (b) may be used singly or in combination of two or more. In certain embodiments, the total content of moisturizers other than component (b) is, for example, 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more, 7% by mass or more, 8% by mass or more, or 9% by mass or more, and 25% by mass or less, 20% by mass or less, 18% by mass or less, 15% by mass or less, 13% by mass or less, 12% by mass or less, or 11% by mass or less, based on the total amount of the oil-in-water emulsion. The total content of moisturizers other than component (b) is most preferably in the range of 2% by mass to 20% by mass, particularly 4% by mass to 15% by mass, based on the total amount of the oil-in-water emulsion.

[0060] <Other ingredients> In certain embodiments, the oil-in-water emulsion comprises additives commonly used in cosmetics, such as pH adjusters, fragrances, preservatives, active ingredients, antioxidants, whitening agents, pigments, colorants, skin conditioning agents, etc. In certain embodiments, the oil-in-water emulsion comprises an active ingredient.

[0061] The oil-in-water emulsion of the present invention contains water. In certain embodiments, the water content relative to the total amount of the oil-in-water emulsion is, for example, 25% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, 48% by mass or more, or 50% by mass or more, and 70% by mass or less, 65% by mass or less, 60% by mass or less, 61% by mass or less, 59% by mass or less, or 57% by mass or less. In a preferred embodiment, the water content relative to the total amount of the oil-in-water emulsion is in the range of 30% by mass to 70% by mass, particularly 35% by mass to 65% by mass.

[0062] In certain embodiments, the pH of the oil-in-water emulsion of the present invention is, for example, less than 7.0, 6.5 or less, 6.0 or less, or 5.5 or less, or 2.0 or more, 2.5 or more, 3.0 or more, or 3.5 or more. The pH of the oil-in-water emulsion of the present invention is most preferably in the range of 3.5 to 5.5.

[0063] In certain embodiments, the oil-in-water emulsion may have a viscosity measured at 25°C of, for example, 300 to 5,000 mPa·s, 500 to 3,000 mPa·s, or 600 to 2,000 mPa·s. The viscosity can be measured by shear viscosity measurement using a rotational viscometer (e.g., Rheolab QC; manufactured by Anton Paar; spindle: ST-22-4V-40; rotation speed: 100 rpm). The oil-in-water emulsion of the present invention has a relatively low viscosity and a light texture.

[0064] In a specific embodiment, the oil-in-water emulsion of the present embodiment is produced, for example, by emulsifying a mixture of component (b), component (c), component (d), other thickeners, emulsifiers, humectants, or water by stirring while heating to 80 to 85°C, followed by cooling to room temperature and mixing the mixture with component (a) and other components.

[0065] In certain embodiments, the oil-in-water emulsion of the present embodiments is in the form of, for example, a cream, a serum, etc. In certain embodiments, the oil-in-water emulsion of the present invention is, in particular, a polishing serum.

[0066] In certain embodiments, oil-in-water emulsion cosmetics have excellent long-term storage stability (for example, they do not undergo phase separation even when stored at 50°C for one month). A severe stability test for predicting long-term product stability can be performed by observing the condition of a sample stored at a constant temperature, such as 45°C or 50°C, for a fixed period of time, such as one month or three months. Furthermore, to more accurately assess stability, the sample can be centrifuged (for example, 10 mL of the emulsion is filled into a centrifuge tube and spun at 4,200 rpm for 15 minutes in an EPPENDORF 5702R centrifuge). The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Example]

[0067] [Preparation of oil-in-water emulsion] The oil-in-water emulsions of Examples 1 to 9 and Comparative Examples 1 to 12 were prepared using the ingredients and formulation ratios listed in Tables 1 to 3. All "%" values ​​in Tables 2 and 3 are by mass, based on the total weight of the oil-in-water emulsion. The ingredients for phases D, E, H, and K were dissolved at room temperature. The ingredients for phase A were dissolved at 80°C. 0.5 to 1.0 kg of oil-in-water emulsions were prepared using a Rayneri mixer. The ingredients for phase B were added to a tank, which was heated to 80°C and mixed at 100 to 500 rpm. After the bulk ingredients in the tank were homogenized, the ingredients for phase C were added to the tank and mixed for 20 minutes until the mixture was swelled. The ingredients for phase A were then gradually added to the tank, and the mixture in the tank was emulsified using a Rayneri mixer at 80°C for 5 minutes, followed by a Turrax homogenizer at room temperature at 10,000 rpm for 1 minute. The mixture was air-cooled to 30° C., and the remaining phase ingredients were added successively at 40° C. or lower. Oil-in-water emulsions of Examples 1 to 9 and Comparative Examples 1 to 12 were obtained.

[0068] [Table 1]

[0069] [Table 2] TIFF2025542166000004.tif226149

[0070] [Table 3] TIFF2025542166000006.tif226149

[0071] The stability of each emulsion was evaluated by the following method: The viscosity was measured as shear viscosity at 25°C using a viscometer (RheolabQC (Anton Paar), spindle: ST-22-4V-40; rotation speed: 100 rpm).

[0072] Stability was evaluated by examining the state of the emulsion after centrifugation (4,200 rpm, 15 minutes) and storage at 50°C for one month. The stability test results indicated that Sangelose 90L (hydroxypropyl methylcellulose stearoxy ether) and Nikkol Batyl Alcohol 100 (batyl alcohol) stabilized the emulsion (Examples 1-3 and 6-9). When hydroxyethyl cellulose was used instead of hydroxypropyl methylcellulose stearoxy ether (Comparative Examples 1 and 3), when hydroxypropyl methylcellulose was used (Comparative Examples 2 and 4), and when no cellulose-based thickener was used (Comparative Examples 5-10), phase separation was observed and the emulsion could not be stabilized. Furthermore, when batyl alcohol was not used (Comparative Examples 11 and 12), the emulsion could not be stabilized. Furthermore, when diutan gum was used instead of Sangelose 90L, the emulsion was stabilized in the same way as Sangelose 90L (Examples 4 and 5). These results indicate that the use of at least one thickener selected from the group consisting of (b) batyl alcohol, and (c) cellulose-based thickeners having an alkyl group with 10 to 30 carbon atoms, and polysaccharide thickeners containing glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides can stabilize an acid-containing oil-in-water emulsion even at low pH (5.5 or less).

Claims

1. (a) at least one acid selected from the group consisting of alpha hydroxy acids (AHA), beta hydroxy acids (BHA), and polyhydroxyalkanoic acids (PHA); (b) batyl alcohol, (c) at least one thickener selected from the group consisting of cellulose-based thickeners having an alkyl group having 10 to 30 carbon atoms and polysaccharide thickeners containing glucose, glucuronic acid, and rhamnose as main chain constituent monosaccharides; and (d) oil An oil-in-water emulsion comprising:

2. 2. The oil-in-water emulsion according to claim 1, wherein the component (a) comprises glycolic acid.

3. 2. The oil-in-water emulsion according to claim 1, wherein the component (a) is contained in an amount of 0.004% by mass or more, preferably in the range of 0.1% by mass or more and 10% by mass or less, particularly preferably in the range of 0.5% by mass or more and 8% by mass or less, or 1% by mass or more and 5% by mass or less, based on the total amount of the oil-in-water emulsion.

4. 2. The oil-in-water emulsion of claim 1, having a pH of 5.5 or less.

5. 10. The oil-in-water emulsion of claim 1, further comprising an emulsifier.

6. 6. An oil-in-water emulsion according to claim 5, wherein the emulsifier is a non-ionic emulsifier.

7. 7. The oil-in-water emulsion of claim 6, wherein the nonionic emulsifier is a polyglycerol fatty acid ester.

8. The oil-in-water emulsion according to claim 1 , further comprising a thickener other than the component (c).

9. 2. The oil-in-water emulsion according to claim 1, wherein the component (d) comprises dicaprylyl ether and / or squalane.

10. 2. The oil-in-water emulsion according to claim 1, which is a polishing serum.

11. A cosmetic method for caring for and / or making up keratinous materials, comprising applying an oil-in-water emulsion according to any one of claims 1 to 10 to keratinous materials, in particular to the skin.