Title of Invention

AQUEOUS EMULSION

Technical Field

[0001] The present invention relates to an aqueous emulsion, and particularly to an oil-in-water type emulsion.

Background Art

[0002] Ultraviolet rays include UV-A and UV-B, with the shorter wavelength UV-B (wavelength: 280 to 320 nm) being absorbed mainly in the surface of the skin, and also being thought to produce sunburn. UV-A (wavelength: 320 to 400 nm), which has a longer wavelength than UV-B, on the other hand, reaches to the dermis of the skin and is thought to produce suntan. Sunscreen performance is generally evaluated by SPF (Sun Protection Factor) and PA (Protection grade of UVA). SPF represents the extent of preventive effect against acute sunburn caused mainly by UV-B, and it is expressed as SPF10, SPF20, SPF30, SPF40, SPF50 or SPF50+ depending on the degree of prevention. PA represents the extent of protective effect against UV-A, and it is expressed as PA+, PA++, PA+++ or PA++++, depending on the degree of prevention.

[0003] Commonly used types of sunscreens include ultraviolet absorbers such as ethylhexyl methoxycinnamate (OMC) and oxobenzone, and ultraviolet scattering agents such as nano-TiO2 and nano-ZnO. In recent years there has been increased review of the cosmetic ingredients used in sunscreens from the viewpoint of environmental considerations, safety and sustainability. However, it has not been easy to formulate sunscreens without using common conventional ultraviolet absorbers and ultraviolet scattering agents or reducing the amounts thereof used, while still exhibiting a high SPF/PA value and a comfortable texture.

[0004] Terephthalylidene dicamphor sulfonic acid (TDSA) is a hydrophilic UV-A absorbent and can be used as a substitute for common hydrophobic UV-A absorbents. Formulation of sunscreen agents in the prior art requires a large amount of oil phase to stably dissolve the hydrophobic UV absorber, but some of the oil phase can be replaced by hydrophilic TDSA to reduce the amount of the oil phase and produce a lighter, less oily texture.

Technical Problem

[0005] TDSA is a very strong acid with two sulfonic acid groups, and it causes emulsion systems to easily collapse. In order to stabilize an emulsion system containing TDSA, therefore, it may be necessary to add a powerful anionic surfactant. However, powerful anionic surfactants are highly irritative on the skin. For example, sulfate-based surfactants also function as cleaning agents, and therefore their addition is not preferred from the viewpoint of safety. Monoalkyl phosphate- type anionic surfactants have lower irritation on skin than other anionic surfactants but also tend to have increased crystallization of TDSA with time. For these reasons it has been difficult to stabilize TDSA- containing emulsion systems and achieve a light texture while having a reduced amount of oil phase. [0006] WO2020/163928A1 describes a sunscreen composition comprising TDSA and a stabilizing surfactant system comprising at least one anionic surfactant and at least one nonionic surfactant.

[0007] But there is still the need to provide an aqueous emulsion comprising terephthalylidene dicamphor sulfonic acid (TDSA) and having excellent stability.

Solution to Problem and Summary of Invention

[0008] The present invention provides an aqueous emulsion comprising (1) terephthalylidene dicamphor sulfonic acid, (2) a phosphorus atom-free compound having at least two hydroxyl groups and an alkyl group of 16 to 22 carbon atoms, or a salt thereof, and (3) a polysaccharide thickener comprising glucose, glucuronic acid and rhamnose as constituent monosaccharides of the main chain.

[0009] In a particular embodiment, component (2) is selected from the group consisting of an organic acid monoglyceride and/or its salt, an alkyl glyceryl ether, and a combination thereof. In a particular embodiment, component (2) comprises glyceryl citrate stearate and/or its salt. In a particular embodiment, the content of component(s) (2) ranges from 0.1 to 10 mass%, preferably 0.2 to 8.0 mass %, more preferably 0.3 to 5.0 mass %, based on the total mass of the aqueous emulsion.

[0010] In a particular embodiment, component (3) in the aqueous emulsion comprises a polysaccharide thickener further comprising at least one selected from the group consisting of rhamnose, fucose, glucose and mannose as constituent monosaccharides on a side chain, and preferably comprises at least one polysaccharide thickener selected from the group consisting of diutan gum, welan gum, gellan gum, and mixtures thereof. In a particular embodiment, the total content of component(s) (3) ranges from 0.01 to 2.0 mass%, preferably 0.02 to 1.5 mass %, more preferably 0.05 to 1.0 mass %, based on the total mass of the aqueous emulsion.

[0011] In a particular embodiment, the aqueous emulsion further comprises an emulsifier other than component (2), selected from the group consisting of a polyglycerol ester of a fatty acid of 12 to 24 carbon atoms comprising from 2 to 12 glycerol units, a glycerol ester of a fatty acid of 12 to 24 carbon atoms, and a combination thereof.

[0012] In a particular embodiment, the aqueous emulsion further comprises a thickener other than component (3) selected from the group consisting of (meth)acrylic (co)polymer, cellulosic thickener and a combination thereof.

[0013] In a particular and preferred embodiment, the aqueous emulsion of the invention comprises:

(1) terephthalylidene dicamphor sulfonic acid,

(2) an organic acid monoglyceride and/or a salt thereof, and/or an alkyl glyceryl ether, preferably glyceryl citrate stearate and/or a salt thereof, and

(3) at least one polysaccharide thickener selected from the group consisting of diutan gum, welan gum, gellan gum, and a combination thereof.

[0014] In a particular embodiment, the aqueous emulsion is an oil-in- water type cosmetic composition, preferably a sunscreen. [0015] The present invention also provides a cosmetic process for caring for keratinic materials comprising the application onto keratinic materials, in particular onto skin, of the aqueous emulsion of the invention. In particular, the aqueous emulsion of the invention is for use as a sunscreen, notably for use in the prevention of sunburns.

Advantageous Effects of Invention

[0016] So, according to the invention it is possible to provide an aqueous emulsion having an excellent UV-protective effect and high stability, as well as a light texture.

Detailed Description of the Invention

[0017] Preferred embodiments of the invention will now be described in detail. However, the present invention is not limited to the embodiments described below.

[0018] In a particular embodiment, the aqueous emulsion of the invention comprises (1) terephthalylidene dicamphor sulfonic acid, (2) a phosphorus atom-free compound having at least two hydroxyl groups and an alkyl group of 16 to 22 carbon atoms, or a salt thereof, and (3) a polysaccharide thickener comprising glucose, glucuronic acid and rhamnose as constituent monosaccharides of the main chain.

[0019] By comprising terephthalylidene dicamphor sulfonic acid (TDSA) as a water-soluble ultraviolet absorber, the aqueous emulsion of this embodiment is provided with the advantage of an excellent UV- protective effect and a light texture, while component (2) and component (3) provide excellent stability.

<Component (1)> [0020] The aqueous emulsion of this embodiment comprises terephthalylidene dicamphor sulfonic acid as component (1). Component (1) in the aqueous emulsion of the embodiment functions as an ultraviolet absorber.

[0021] Terephthalylidene dicamphor sulfonic acid (common name: Ecamsule) (bicyclo[2.2.1]heptane-l -methanesulfonic acid, 3,3'-(l,4- phenylenedimethylidyne)bis[7.7]-dimethyl-2-oxo) is a water-soluble benzylidene camphor derivative, being an organic compound that absorbs UV-A (maximum absorption wavelength: 345 nm).

Terephthalylidene dicamphor sulfonic acid has almost no dermal penetration, and has been reported to cause virtually no primary irritation of skin and to be safe for the human body. Terephthalylidene dicamphor sulfonic acid is marketed under the name Mexoryl SX (Chimex), for example.

[0022] Terephthalylidene dicamphor sulfonic acid may also be in the form of a salt. Examples of salts include inorganic salts such as sodium salts, potassium salts, calcium salts and magnesium salts, or organic salts such as methylamine salts and dimethylamine salts, with sodium salts being preferred.

[0023] In a particular embodiment, in the aqueous emulsion of this embodiment, the content of component (1) is of 0.01 mass% or greater, 0.05 mass% or greater or 0.10 mass% or greater, and 15 mass% or lower, 14 mass% or lower, 13 mass% or lower, 12 mass% or lower, 11 mass% or lower or 10 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the content of component (1) ranges from 0.01 mass% to 15 mass%, particularly from 0.05 mass% to 12 mass%, preferably from 0.10 to 10 mass%, and most preferably from 0.5 mass% to 5% mass, based on the total mass of the aqueous emulsion.

<Component (2)>

[0024] The aqueous emulsion of the invention comprises, as component (2), a phosphorus atom-free compound having at least two hydroxyl groups and an alkyl group of 16 to 22 carbon atoms, or a salt thereof.

[0025] Component (2) is an amphiphilic substance having a hydrophilic portion and a lipophilic portion in the molecule of the compound. In the aqueous emulsion of the invention, component (2) functions as an emulsifier, thus stabilizing the aqueous emulsion and avoiding crystallization of component (1).

[0026] According to a specific embodiment, the alkyl group of the compound of component (2) has 16 to 20 carbon atoms or 16 to 18 carbon atoms. Component (2) may have 2, 3, 4, 5 or 6 hydroxyl groups in the molecule, for example.

[0027] Component (2) is a compound that is free of phosphorus atoms. The present inventors have found that rapid crystallization of terephthalylidene dicamphor sulfonic acid can be produced in the emulsion when it is obtained using an amphiphilic polymer surfactant that is a monoalkyl phosphate. Component (2) is preferably a compound comprising a carbon atom, a hydrogen atom and an oxygen atom, or its salt. Component (2) may be an anionic surfactant.

[0028] According to a specific embodiment, component (2) is selected from the group consisting of an organic acid monoglyceride and/or a salt thereof, an alkyl glyceryl ether, and a combination thereof. According to a specific embodiment, component (2) preferably comprises an organic acid monoglyceride and/or a salt thereof, and most preferably comprises glyceryl citrate stearate and/or its salt. [0029] In a particular embodiment, an organic acid monoglyceride is a monoester of an organic acid and an ester of a fatty acid of 16 to 22 carbon atoms and glycerin, for example. In particular, the organic acid in a monoglyceride of an organic acid may be an aliphatic hydroxy acid such as citric acid. Examples of salts include inorganic salts such as sodium salts, potassium salts, calcium salts and magnesium salts, or organic salts such as methylamine salts and dimethylamine salts, with sodium salts being preferred. According to a specific embodiment, glyceryl stearate citrate and glyceryl fatty acid succinates, and their salts, are examples for the phosphorus atom-free organic acid monoglyceride or its salt having at least two hydroxyl groups and an alkyl group of 16 to 22 carbon atoms.

[0030] An alkyl glyceryl ether may have two hydroxyl groups, for example. Batyl alcohol, chimyl alcohol and selachyl alcohol are examples for phosphorus atom-free alkyl glyceryl ethers having at least two hydroxyl groups and an alkyl group of 16 to 22 carbon atoms. [0031] In the aqueous emulsion of this embodiment, a single component (2) may be used as a single type alone, or multiple types may be used in combination. In a particular embodiment, the total content of component(s) (2) is of 0.1 mass% or greater, 0.2 mass% or greater, 0.3 mass% or greater, 0.4 mass% or greater, 0.5 mass% or greater or 0.6 mass% or greater, and 3.0 mass% or lower, 2.5 mass% or lower, 2.2 mass% or lower, 2.0 mass% or lower, 1.8 mass% or lower, 1.7 mass% or lower, 1.6 mass% or lower, 1.5 mass% or lower, 1.4 mass% or lower or 1.3 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the total content of component(s) (2) ranges from 0.1 mass% to 10 mass%, and particularly from 0.2 mass% to 8.0 mass% or 0.3 mass% to 5.0 mass%, based on the total mass of the aqueous emulsion.

<Component (3)>

[0032] The aqueous emulsion of the invention comprises, as component (3), a polysaccharide thickener that comprises glucose, glucuronic acid and rhamnose as constituent monosaccharides of the main chain. If the aqueous emulsion comprises a polysaccharide thickener as component (3), it will be able to exhibit high stability at high temperature while maintaining suitable viscosity.

[0033] Component (3) may comprise a polysaccharide thickener having a main chain with a structural unit comprising glucose, glucuronic acid, glucose and rhamnose bonded linearly in that order. The polysaccharide thickener of component (3) may also have a side chain as part of the polysaccharide structure, or it may lack a side chain. In a particular embodiment, the side chain has one or more selected from the group consisting of rhamnose, fucose, glucose and mannose as a side chain constituent monosaccharide. In a particular and preferred embodiment, the polysaccharide thickener may have a main chain with a structural unit comprising glucose, glucuronic acid, glucose and rhamnose bonded linearly in that order, with rhamnose as a side chain. The polysaccharide thickener may be obtained from a microbe such as a bacterium.

[0034] According to a specific embodiment, the polysaccharide thickener comprises at least one selected from the group consisting of diutan gum, welan gum, gellan gum, and a combination thereof. Preferably, the polysaccharide thickener is diutan gum. Diutan gum (INCI: Sphingomonas ferment extract) is a polysaccharide obtained by aerobic fermentation of a com syrup starting material using Alcaligenes microbes.

[0035] In the aqueous emulsion of the invention, a single component (3) may be used as a single type alone, or multiple types may be used in combination. In a particular embodiment, the total content of component(s) (3) is of 0.01 mass% or greater, 0.02 mass% or greater, 0.03 mass% or greater, 0.04 mass% or greater, 0.05 mass% or greater, 0.06 mass% or greater or 0.07 mass% or greater, and 1.0 mass% or lower, 0.8 mass% or lower, 0.6 mass% or lower, 0.5 mass% or lower, 0.4 mass% or lower, 0.3 mass% or lower, 0.2 mass% or lower, 0.15 mass% or lower or 0.1 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the total content of component(s) (3) ranges from 0.01 mass% to 2.0 mass%, and particularly from 0.05 mass% to 1.5 mass% or 0.05 mass% to 1.0 mass%, based on the total mass of the aqueous emulsion. The aqueous emulsion of this embodiment has high temperature stability even with a low amount of thickener used.

< UV filter> [0036] According to a specific embodiment, the aqueous emulsion also includes a UV filter other than component (1). UV filters include organic UV filters (organic UV absorbers) and inorganic UV filters (UV scattering agents). Organic UV absorbers include lipophilic organic UV absorbers and hydrophilic organic UV absorbers, each including UV-A absorbers, UV-B absorbers, and UV-A and UV-B absorbers.

[0037] The term "lipophilic organic UV filter" means an organic UV filter which is soluble in oils at a concentration of at least 1% by weight relative to the total weight of the oil at room temperature (25 °C) and atmosphere pressure (10 ⁵ Pa).

[0038] Lipophilic organic UV-A absorbers include aminobenzophenone compounds, dibenzoylmethane compounds, anthranilic acid compounds and 4,4-diaryl butadiene compounds. Aminobenzophenone compounds include diethylamino hydroxybenzoyl hexyl benzoate (DHHB, Product name: Uvinul A+ by BASF), and mixtures thereof. Dibenzoylmethane compounds include 4-isopropyldibenzoylmethane (Product Name: Eusolex 8020 by Merck), l-(4-methoxy-l-benzofuran-5-yl)-3-phenylpropane-l, 3-dione (Product Name: Pongamol by Quest), l-(4-( rt-butyl)phenyl)-3-(2- hydroxyphenyl)propane-l, 3 -dione and butyl methoxydibenzoylmethane (Product Name: Parsol 1789 by DSM). Anthranilic acid compounds include menthyl anthranilate (Product name: NEO HELIPAN MA by Symrise), and mixtures thereof. Also, 4,4-diarylbutadiene compounds include 1,1 -dicarboxy (2,2'- dimethylpropyl)-4,4-diphenylbutadiene, diphenyl butadiene malonate and malononitrile, and mixtures thereof.

[0039] Lipophilic organic UV-B absorbers include cinnamate compounds, salicylic compounds, anilino triazine compounds, benzoic acid compounds, diphenylacrylate compounds, benzylidene camphor compounds, phenylbenzimidazole compounds, imidazoline compounds, benzalmalonate compounds and mecocyanine compounds, and mixtures thereof.

[0040] Cinnamate compounds include ethylhexyl methoxycinnamate (product name: PARSOL CX by DSM), isopropyl ethoxycinnamate, isoamyl methoxycinnamate (product name: NEO HELIOPAN E 1000 by Symrise), diisopropyl methylcinnamate, cinoxate, glyceryl ethylhexanoate dimethoxy cinnamate, octyl cinnamate, isopropylethyl cinnamate, diisopropylethyl cinnamate, methyldiisopropyl cinnamate, propylmethoxy cinnamate, isopropylmethoxy cinnamate, isoamylmethoxy cinnamate, octylmethoxy cinnamate, cyclohexylmethoxy cinnamate, ethyl-a-cyano-J3-phenyl cinnamate, 2- ethylhexyl-a-cyano-P-phenyl cinnamate, glyceryl mono-2- ethylhexanoyl-diparamethoxy cinnamate and 3,4,5-trimethoxy-3- methyl-4-cinnamate [methylbis(trimethylsiloxy)silyl]butyl, and mixtures thereof.

[0041] Salicylic compounds include ethylhexyl salicylate (product name: NEO HELIOPAN OS by Symrise), homosalate (product name: Eusolex HMS by Rona/EM industries), amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate and -isopropanolphenyl salicylate, and mixtures thereof.

[0042] Anilino triazine compounds include tris-anilino triazine compounds such as ethylhexyl triazone (product name: UVINUL T- 150 by BASF), 2,4,6-tris(dineopentyl 4'-aminobenzalmalonate)-s- triazine and 2,4,6-tris(diisobutyl 4'-aminobenzalmalonate)-s-triazine and bis-anilino triazine compounds such as diethylhexyl butamido triazone (product name: UVASORB HEB by SIGMA 2 V), and mixtures thereof.

[0043] Benzoic acid compounds include ura-aminobenzoates (PABA) such as ethyl PABA jura-aminobenzoate), ethyl dihydroxypropyl PABA, ethylhexyl dimethyl PABA, PABA monoglycerin ester, N,N-dipropoxy PABA ethyl ester, N,N-diethoxy PABA ethyl ester, N,N-dimethyl PABA ethyl ester and N,N-dimethyl PABA butyl ester, and mixtures thereof.

[0044] Diphenylacrylate compounds include octocrylene (product name: UVINUL N539 by BASF) and etocrylene (product name: UVINUL N35 by BASF). Benzylidene camphor compounds include 3 -benzylidene camphor (product name: MEXORYL SD by CHIMEX), methylbenzylidene camphor (product name: EUSOLEX 6300 by MERCK), and polyacrylamidomethyl benzylidene camphor (product name: MEXORYL SW by CHIMEX), and mixtures thereof.

[0045] Phenylbenzimidazole compounds include phenylbenzimidazole sulfonic acid (product name: Eusolex 232 by Merck). Imidazoline compounds include ethylhexyl dimethoxybenzylidene dioxoimidazoline propionate. Benzalmalonate compounds include polyorganosiloxanes containing a benzalmalonate moiety, such as Polysilicone-15 (product name: Parsol SLX by DSM) and di-neopentyl 4'-methoxybenzalmalonate, and mixtures thereof, for example.

[0046] Lipophilic UV-A and UV-B absorbers include benzophenone compounds, such as benzophenone-1 (product name: UVINUL 400 by BASF), benzophenone-2 (product name: UVINUL 500 by BASF), benzophenone-3 (product name: UVINUL M40 by BASF), benzophenone-6 (product name: Helisorb 11 by Norquay), benzophenone- 8 (product name: Spectra-Sorb UV-24 by American Cyanamid), benzophenone- 10, benzophenone-11 and benzophenone - 12; benzotriazole compounds such as drometrizole trisiloxane (product name: Silatrizole by Rhodia Chimie) and bumetrizole (product name: TINOGUARTD AS by Ciba); bis-resorcinyl triazine compounds such as bis-ethylhexyloxyphenol methoxyphenyl triazine (product name: TINOSORB S by Ciba); and benzoxazole compounds such as 2,4- bis[5-(l-dimethylpropyl)benzoxazol-2-yl(4-phenyl)imino]-6-(2 - ethylhexyl)imino-l, 3, 5 -triazine (product name: Uvasorb K2A by Sigma 3 V), and mixtures thereof.

[0047] Organic UV absorber may include a hydrophilic organic UV absorber. The term "hydrophilic organic UV filter" means an organic UV filter which is soluble in water at a concentration of at least 1% by weight relative to the total weight of the water at room temperature (25°C) and atmosphere pressure (10 ⁵ Pa). A water dispersion of a lipophilic organic UV absorber can be also regarded as a hydrophilic organic UV absorber. [0048] Hydrophilic organic UV-A absorbers include bisbenzoxazolyl derivatives, such as disodium phenyl dibenzimidazole tetrasulfonate and salts thereof (Product Name: Neo Heliopan AP by Haarmann and Reimer), and mixtures thereof.

[0049] Hydrophilic organic UV-B absorbers include -aminobenzoic (PABA) derivatives, such as PABA, glyceryl PABA and PEG-25 PABA, and salts thereof (product name: Uvinul P25 by BASF, for example), benzimidazole sulfonic acid compounds such as phenylbenzimidazole sulfonic acid and salts thereof (product name: Eusolex 232 by Merck, for example), ferulic acid and salts thereof, salicylic acids and salts thereof, DEA methoxycinnamate and salts thereof, benzylidene camphor sulfonic acid and salts thereof (product name: Mexoryl SL by Chimex, for example), and camphor benzalkonium methosulfate and salts thereof (product name: Mexoryl SO by Chimex, for example), and mixtures thereof.

[0050] An example of a water dispersion of a lipophilic organic UV absorber is a water dispersion of a lipophilic UV-A and UV-B filter, including a water dispersion such as a water dispersion of an alkylene bis-benzotriazolylphenol compound such as methylene bis- benzotriazolyl tetramethylbutylphenol (product name: TINO SORB M by BASF).

[0051] Hydrophilic organic UV-A and UV-B absorbers include benzophenone-4 and salts thereof (product name: Uvinul MS40 by BASF, for example), benzophenone-5 and salts thereof, benzophenone- 9 and salts thereof, and mixtures thereof. [0052] UV filter may comprise an inorganic UV filter (UV scattering agent). The UV scattering agent may be in the form of fine particles such that the mean primary particle size ranges from 1 nm to 50 pm, preferably 5 nm to 500 nm and more preferably 10 nm to 200 nm. The mean primary particle size is based on the arithmetic mean diameter. [0053] The UV scattering agent is preferably a hydrophilic-treated or untreated metal oxide. Such metal oxides include titanium oxide and zinc oxide.

[0054] In a particular embodiment, the total content of UV absorbers other than component (1) ranges from 2 to 50 mass%, in particular from 5 to 40 mass%, preferably from 10 to 25 mass% or from 10 to 20 mass%, based on the total mass of the aqueous emulsion.

<Emulsifier>

[0055] According to a specific embodiment, the aqueous emulsion also includes an emulsifier other than component (2). In a particular embodiment, the emulsifier is a nonionic emulsifier (nonionic surfactant).

[0056] Examples of nonionic surfactants include esters of a fatty acid and polyglycerol (polyglycerin fatty acid esters) and esters of a fatty acid and glycerol (glycerin fatty acid esters), and mixtures thereof.

[0057] According to a specific embodiment, a polyglycerin fatty acid ester is a polyglycerin acid of a fatty acid having 12 to 24, preferably 16 to 22, more preferably 16 to 20 and most preferably 18 carbon atoms. Examples for constituent fatty acids include palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, a-linolenic acid, y-linolenic acid, isostearic acid, arachidic acid, arachidonic acid and behenic acid. The fatty acid may be saturated or unsaturated, but it is preferably saturated. The glycerol units in the polyglycerin fatty acid ester (polymerization degree of the glycerin) may be 2 to 12, preferably 2 to 10, more preferably 2 or 8, and most preferably 2 or 6 for example. [0058] According to a specific embodiment, the poly glycerin fatty acid ester is selected from the group consisting of polyglyceryl-2 stearate, polyglyceryl-2 isostearate, polyglyceryl-2 oleate, polyglyceryl-6 stearate, polyglyceryl-6 behenate, and mixtures thereof. [0059] According to a specific embodiment, a glycerin fatty acid ester is a glycerin ester of a fatty acid having 12 to 24, preferably 16 to 22, more preferably 16 to 20 and most preferably 18 carbon atoms.

Examples of fatty acids include palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, a-linolenic acid, y-linolenic acid, arachidic acid, arachidonic acid and behenic acid. The fatty acid may be saturated or unsaturated, but it is preferably saturated. According to a specific embodiment, the glycerin fatty acid ester is selected from the group consisting of glyceryl stearate, glyceryl oleate, glyceryl myristate, glyceryl coconut fatty acid esters, glyceryl undecylenate, and mixtures thereof.

[0060] An emulsifier other than component (2) is preferably a solid at ordinary temperature (for example, 25°C). According to a specific embodiment, emulsifiers other than component (2) is preferably selected from the group consisting of a polyglycerol ester of a fatty acid having 12 to 24 carbon atoms comprising 2 to 12 glycerol units, a glycerol ester of a fatty acid having 12 to 24 carbon atoms, and a combination thereof, more preferably selected from the group consisting of a polyglycerol ester of a fatty acid having 12 to 24 carbon atoms comprising 2 to 12 glycerol units for example. According to a specific preferred embodiment, emulsifiers other than component (2) may be polyglyceryl-6 stearate and polyglyceryl-6 behenate, for example. An example of a commercial product comprising a combination of polyglyceryl-6 stearate and polyglyceryl-6 behenate is TEGO CARE PBS 6 (Evonik Operations GmbH).

[0061] According to a specific embodiment, the total content of emulsifiers other than component (2) is of 0.1 mass% or greater, 0.2 mass% or greater, 0.5 mass% or greater, 0.7 mass% or greater, 1.0 mass% or greater or 1.2 mass% or greater, and 10 mass% or lower, 8 mass% or lower, 6 mass% or lower, 5 mass% or lower, 4 mass% or lower, 3 mass% or lower, 2.5 mass% or lower, 2.2 mass% or lower or 2 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the content of emulsifiers other than component (2) ranges from 0.5 mass% to 10 mass%, and particularly from 0.5 mass% to 5 mass% or 1 mass% to 3 mass%, based on the total mass of the aqueous emulsion.

<Thickener>

[0062] According to a specific embodiment, the aqueous emulsion includes a thickener other than component (3). Examples of thickeners other than component (3) include (meth)acrylic (co)polymer, cellulosic thickener, polysaccharide thickeners such as xanthan gum or dehy droxanthan gum. Thickeners other than component (3) preferably may be selected from the group consisting of (meth)acrylic (co)polymer, cellulosic thickener and a combination thereof. [0063] A (meth)acrylic-based copolymer 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. There are no particular restrictions on the (meth)acrylic acid ester, which may be an alkyl (meth)acrylic acid ester, or the same wherein the alkyl group of the (meth)acrylic acid ester has been substituted with a substituent such as a hydroxyl group, and it is preferably an alkyl (meth)acrylic acid ester. Alkyl (meth)acrylic acid esters include alkyl (meth)acrylic acid esters with alkyl groups of 10 to 30 carbon atoms and alkyl (meth)acrylic acid esters with alkyl groups of 1 to 9 carbon atoms, and are preferably alkyl (meth)acrylic acid esters with alkyl groups of 10 to 30 carbon atoms. A (meth)acrylic-based copolymer may be a copolymer of at least one monomer selected from the group consisting of (meth)acrylic acid and alkyl (meth)acrylic acid esters with alkyl groups of 1 to 9 carbon atoms, and at least one monomer selected from the group consisting of alkyl (meth)acrylic acid esters with alkyl groups of 10 to 30 carbon atoms.

[0064] A (meth)acrylic-based copolymer may also comprise a structural unit derived from (meth)acrylic acid. A structural unit derived from (meth)acrylic acid is a structural unit obtained by radical addition polymerization of (meth) acrylic acid. A structural unit obtained by radical addition polymerization may be any one with the same chemical structure as a structural unit obtained by radical addition polymerization, and may optionally be a structural unit obtained by a method other than radical addition polymerization. [0065] A (meth)acrylic-based copolymer may also be crosslinked.

The crosslinking agent may be a compound having a plurality of ethylenic unsaturated groups in the molecule, such as a compound with a plurality of allyl ether groups in the molecule. Specifically, the crosslinking agent may be pentaerythrityl allyl ether, sucrose allyl ether, propylene allyl ether or sucrose allyl ether. A (methacrylicbased copolymer may be crosslinked with one or more crosslinking agents.

[0066] When a (meth)acrylic-based copolymer is a carboxy group, at least a portion of the carboxy groups may be neutralized. As used herein, "carboxy group" includes both the group COOH and the neutralized COOH group. When the carboxy group is neutralized, the counter cation of the carboxylic acid anion is not particularly restricted, and examples include alkali metal ions such as sodium ion and potassium ion, and ammonium ion or organic ammonium ions.

[0067] A (meth)acrylic-based copolymer may also include a carbomer. Component (B) may be a commercial product, examples of commercial products including Carbopol™ Ultrez 30 Polymer (EX- 1142), Carbopol™ Ultrez 10, Carbopol™ ETD 2020, Carbopol™ Ultrez 20 Polymer and Pemulen TR-1, by Lubrizol Corp , Aristo flex™ AVC by Clariant, Simulgel™ NS MB by Seppic S.A.

[0068] According to a specific embodiment, the aqueous emulsion includes a cellulose-based thickener. Examples of cellulose-based thickeners include ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, hydroxypropyl methylcellulose stearoxy ether, cellulose gum, carboxymethyl cellulose, and mixtures thereof. According to a specific embodiment, the cellulose-based thickener comprises an alkyl group of 10 to 30 carbon atoms from the viewpoint of further increasing the high temperature stability and further inhibiting stickiness of the aqueous emulsion. According to a specific preferred embodiment, the cellulose- based thickener with an alkyl group of 10 to 30 carbon atoms is hydroxypropyl methylcellulose stearoxy ether.

<Oil agent>

[0069] According to a specific embodiment, the aqueous emulsion of the invention includes an oil agent other than component (1), component (2) and component (3). The oil agent may be a liquid oil or a paste oil, for example. A liquid oil may be either a non-polar liquid oil or a polar liquid oil. Examples of liquid oils include alkyl palm (caprylates/caprates), squalane, sunflower oil, dimethicone, meadowfoam oil, almond oil, polyglyceryl-2 triiso stearate, glyceryl tri(caprylate/caprate), isotridecyl isononanoate, isononyl isononanoate, ethyl hexyl palmitate, pentaerythrityl tetraethyl hexanoate, pentaerythrityl tetraisostearate, cetyl ethylhexanoate, diisopropyl sebacate, tridecyl trimellitate, hydrogenated polydecene and hydrogenated polyisobutene, and mixtures thereof.

[0070] In a particular embodiment, the content of the oil agent is of 3 mass% or greater, 5 mass% or greater, 8 mass% or greater, 10 mass% or greater, 12 mass% or greater, 14 mass% or greater or 16 mass% or greater, and 40 mass% or lower, 30 mass% or lower, 20 mass% or lower, 18 mass% or lower, 17 mass% or lower, 15 mass% or lower, 13 mass% or lower, or 10 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the content of the oil agent ranges from 3 mass% to 50 mass%, and particularly from 5 mass% to 45 mass%, based on the total mass of the aqueous emulsion. [0071] In a particular embodiment, the liquid oil content is of 3 mass% or greater, 5 mass% or greater, 7 mass% or greater, 8 mass% or greater, 10 mass% or greater, 12 mass% or greater or 14 mass% or greater, and 40 mass% or lower, 30 mass% or lower, 20 mass% or lower, 18 mass% or lower, 17 mass% or lower, 15 mass% or lower, 13 mass% or lower, 10 mass% or lower or 8 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the content of the liquid oil ranges from 3 mass% to 50 mass%, and particularly from 5 mass% to 45 mass%, based on the total mass of the aqueous emulsion.

<Humectcmt>

[0072] According to a specific embodiment, the aqueous emulsion includes a humectant in addition to component (1), component (2) and component (3). Examples of humectants include polyhydric alcohols of 3 to 5 carbon atoms. Examples of polyhydric alcohols include those with 2 or 3 alcoholic hydroxyl groups. Examples of polyhydric alcohols of 3 to 5 carbon atoms include glycerin, 1,3-butylene glycol, pentylene glycol, propanediol, and mixtures thereof.

[0073] In a particular embodiment, the content of a polyhydric alcohol of 3 to 5 carbon atoms is of 2 mass% or greater, 5 mass% or greater, 8 mass% or greater, 10 mass% or greater, 12 mass% or greater, 15 mass% or greater, 18 mass% or greater or 20 mass% or greater, and 30 mass% or lower, 28 mass% or lower, 25 mass% or lower, 23 mass% or lower, 20 mass% or lower, 18 mass% or lower or 15 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the content of the content of a polyhydric alcohol of 3 to 5 carbon atoms ranges from 2 mass% to 30 mass%, and particularly from 10 mass% to 30 mass%, based on the total mass of the aqueous emulsion.

<Other components>

[0074] According to a specific embodiment, the aqueous emulsion also contains additives commonly used in cosmetics, such as pH adjustors, perfumes, antiseptic agents, active components, antioxidants, skin whiteners, pigments, coloring agents, soothing agents, , skin conditioning agents, and mixtures thereof. According to a specific embodiment, the aqueous emulsion comprises an active component, and in particular a soothing agent.

[0075] In a particular embodiment, the pH of the aqueous emulsion of this embodiment ranges from 5 to 9 or 6 to 8, for example, and preferably ranges from 7 to 8.

[0076] According to a specific embodiment, the aqueous emulsion has a viscosity of 500 to 10,000 mPa-s, 700 to 9,000 mPa-s or 700 to 8,000, for example, as measured at 25°C. The viscosity can be measured based on the shear viscosity, using a rotational viscometer (for example, Rheolab QC by Anton Paar, spindle: ST-22-4V-40; rotational speed: 100 rpm). In a particular embodiment, the aqueous emulsion of the invention has relatively low viscosity and a light texture.

[0077] According to a specific embodiment, the aqueous emulsion of the invention is an oil-in-water composition. The aqueous emulsion of the invention contains water. In a particular embodiment, the total content of water is of 30 mass% or greater, 35 mass% or greater, 45 mass% or greater, 47 mass% or greater, 49 mass% or greater, 51 mass% or greater, 53 mass% or greater, 55 mass% or greater, 58 mass% or greater, 60 mass% or greater or 61 mass% or greater, and 70 mass% or lower, 65 mass% or lower, 63 mass% or lower, 61 mass% or lower, 59 mass% or lower or 57 mass% or lower, based on the total mass of the aqueous emulsion. In a preferred embodiment, the content of the content of water ranges from 30 mass% to 70 mass%. and particularly from 35 mass% to 65 mass%, based on the total mass of the aqueous emulsion.

[0078] According to a specific embodiment, the aqueous emulsion of the invention is produced, for example, by stirring and mixing component (1), component (2) and component (3), with the other thickener, oil agent, emulsifier, and water, while heating at 80 to 85°C, emulsifying the mixture, and then cooling the mixture to room temperature and mixing in the other components.

[0079] According to another specific embodiment, the aqueous emulsion of the invention is in the form of a cream or a fluid, for example. In a preferred embodiment, the aqueous emulsion is an oil- in-water type emulsified cosmetic composition, and especially a sunscreen.

[0080] The oil-in-water emulsified cosmetic compositionaccording to a specific embodiment has excellent long-term storage stability (for example, it does not undergo phase separation when stored for 3 months at 45°C). In a particular embodiment, a sunscreen according to the invention has an ultraviolet shielding power of SPF30, SPF40, SPF50 or SPF50+, and most preferably SPF50+.

< Use and process>

[0081] The present invention also provides a cosmetic process for caring for keratinic materials comprising the topical application onto keratinic materials, in particular onto skin, of the aqueous emulsion of the invention.

[0082] The present invention also provides an aqueous emulsion, as described above, for use as a sunscreen.

[0083] Furthermore, the present invention also provides an aqueous emulsion, as described above, for use in the prevention of sunburns. [0084] The present invention will now be explained in specific detail through the following examples, with the understanding that the invention is not limited by the examples.

Examples

[0085] [Preparation of aqueous emulsions]

Aqueous emulsions for Examples 1 to 5 and Comparative

Examples 1 to 8 were prepared with the components and mixing ratios listed in Table 1 to Table 3. The "%" values in Tables 2 and 3 are all wt% values, based on the total weight of the aqueous emulsion. The ingredients of Phase A were dissolved at 80°C. The ingredients of Phases DI and D2 were dissolved at room temperature. A 0.5 to 1.0 kg portion of the emulsion was prepared using a RAYNERE The components of Phase B were added to a tank and the tank was heated at 80°C. After the bulk components in the tank became homogeneous, the ingredients of Phase C were added into the tank and mixed at 500 rpm until the mixture swelled. Phase A was then added into the tank gradually while mixing at 1,500 rpm. The mixture was emulsified with a RAYNERI for 5 min at 80°C, and then homogenized with a TURRAX for 1 min (10,000 rpm) at room temperature. The mixture was air-cooled down to 30°C, and the ingredients of the remaining phases were added in order. Aqueous emulsions were obtained for Examples 1 to 5 and Comparative Examples 1 to 8.

[0085] [Table 1]

[0086] [Table 2]

[0087] [Table 3]

[0088] [Evaluation]

The stability of each obtained emulsion was evaluated by the following method. The pH of each emulsion was just above 7. The viscosity was measured as the shear viscosity using a viscometer (Rheolab QC by Anton Paar, spindle: ST-22-4V-40; rotational speed: 100 rpm) at 25°C.

[0089] A 30 g portion of the emulsion was placed in a transparent container 50 mL). The cover of the glass bottle was then sealed. The glass bottle was stored at a constant temperature of 45°C. After standing for 3 months, the state of phase separation was visually observed. The results are shown in Tables 2 and 3. In the tables, "Stable" means that no phase separation was observed, and "Aqueous Exudate" means that separation of aqueous phase was observed.

[0090] The aqueous emulsions obtained in Examples 1 to 5 (according to the invention) exhibited excellent stability without phase separation after a period of 3 months at 45 °C. However, separation between the oil phase and aqueous phase was observed in Comparative Examples 1 , 2, 4, 5, 7 and 8.

[0091] The glass bottle containing the emulsion was also stored at a constant temperature of 4°C for three months and the presence or absence of crystals was observed by using an optical microscope (LEICA DM 2700M; Leica Microsystems Co., Ltd.; x 200) at 25°C. None of the aqueous emulsions obtained in Examples 1 to 5 (according to the invention) and Comparative Examples 1 and 2 exhibited crystallization, but crystallization was exhibited by the aqueous emulsions obtained in Comparative Examples 3 to 6 at 3 days (3D), by the aqueous emulsion of Comparative Example 7 at 2 weeks (2W), and by the aqueous emulsion of Comparative Example 8 at 4 weeks (4W). [0092] In conclusion, the aqueous emulsions according to the invention (Examples 1 to 5) advantageously exhibit both an excellent stability without phase separation after a period of 3 months at 45°C; and no crystallization after storage at 4°C for 3 months, whereas the comparative examples show either phase separation and/or crystallization after storage at 4°C. And these results on excellent stability and no crystallization at 4°C in an aqueous emulsion of the invention comprising (1) terephthalylidene dicamphor sulfonic acid, are related to the combination of (2) a phosphorus atom- free compound having at least two hydroxyl groups and an alkyl group of 16 to 22 carbon atoms, or a salt thereof, and (3) a polysaccharide thickener comprising glucose, glucuronic acid and rhamnose as constituent monosaccharides of the main chain.