JP7498577B2 - Oil-in-water emulsion cosmetics - Google Patents

Description

The present invention relates to an oil-in-water emulsion cosmetic that has excellent UV protection effects.

In recent years, as protection from ultraviolet rays has become increasingly important in daily life, the need for sunscreen cosmetics has also increased. In response to such market needs, oil-in-water emulsion sunscreen cosmetics, which have a refreshing feel and are easy to use over time, have been developed.

In these oil-in-water emulsion cosmetics, ultraviolet absorbing agents and ultraviolet scattering agents are used to enhance the ultraviolet ray protection effect. In particular, metal oxide powders such as zinc oxide and titanium oxide are used as ultraviolet ray scattering agents.
However, when a metal oxide powder is blended in an oil-in-water emulsion cosmetic, there are problems in that the texture is poor and the stability is insufficient. In order to improve such problems, for example, Patent Document 1 discloses a makeup cosmetic containing a crosspolymer containing 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof, (meth)acrylic acid and/or an ester thereof, and N,N-dimethylacrylamide as constituent units, and a hydrophilic treated powder.

JP 2012-241002 A

However, when a large amount of metal oxide powder is blended into an oil-in-water emulsion cosmetic in order to enhance the UV protection effect, sufficient emulsion stability cannot be obtained, and a dry feeling may be felt after application. This dry feeling can be improved to some extent by blending an oil agent, but on the other hand, it has been found that the emulsion stability and spreadability during application decrease, and further stickiness occurs after application.
The present invention aims to provide an oil-in-water emulsion cosmetic which has an excellent ultraviolet protection effect, excellent emulsion stability, good spreadability upon application, and excellent usability with reduced dryness and stickiness after application.

The inventors have discovered that by using a hydrophobized fine particle metal oxide and a sterol ester having an average primary particle size within a predetermined range, and by setting the content of the hydrophobized fine particle metal oxide within a predetermined range, it is possible to obtain an oil-in-water emulsion cosmetic that has excellent UV protection ability, high emulsion stability, good spreadability upon application, and excellent usability with reduced dryness and stickiness after application.

That is, the present invention provides an oil-in-water emulsion cosmetic comprising the following components (A) and (B):
Component (A): A hydrophobized fine particle metal oxide having an average primary particle diameter of less than 100 nm. Component (B): A sterol ester. The oil-in-water emulsion cosmetic contains component (A) in an amount of 7% by mass or more and 30% by mass or less.

The present invention can provide an oil-in-water emulsion cosmetic that has excellent UV protection effect, excellent emulsion stability, good spreadability when applied, and excellent usability with reduced dryness and stickiness after application.

[Oil-in-water emulsion cosmetics]
The oil-in-water emulsion cosmetic of the present invention (hereinafter, also referred to as "emulsion cosmetic") is an oil-in-water emulsion cosmetic containing the following components (A) and (B):
Component (A): hydrophobized fine particle metal oxide having an average primary particle size of less than 100 nm. Component (B): sterol ester. The content of component (A) is 7% by mass or more and 30% by mass or less.
In the present invention, the term "hydrophobically treated fine particle metal oxide" refers to a fine particle metal oxide whose surface has been subjected to a hydrophobizing treatment.

<Component (A): Hydrophobized fine metal oxide particles having an average primary particle size of less than 100 nm>
The oil-in-water emulsion cosmetic of the present invention contains, as component (A), fine particles of a hydrophobized metal oxide having an average primary particle size of less than 100 nm.
From the viewpoint of scattering ultraviolet rays and enhancing the ultraviolet protection effect, the metal oxide of component (A) is preferably one or more selected from the group consisting of zinc oxide, titanium oxide, and cerium oxide, more preferably one or more selected from the group consisting of zinc oxide and titanium oxide. In addition, these fine particle metal oxides can contain divalent or higher metals, and metals such as iron, zirconium, calcium, manganese, magnesium, yttrium, etc. or their oxides can be contained alone or in appropriate combination of two or more in the metal oxide.

From the viewpoint of enhancing the UV protection effect and improving the emulsion stability, the average primary particle diameter of component (A) is less than 100 nm, preferably 90 nm or less, more preferably 70 nm or less, even more preferably 50 nm or less, even more preferably 40 nm or less, even more preferably 30 nm or less, and preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more. More specifically, from the viewpoints described above, the average primary particle diameter of component (A) is preferably 1 to 90 nm, more preferably 1 to 70 nm, even more preferably 1 to 50 nm, even more preferably 5 to 50 nm, even more preferably 10 to 50 nm, even more preferably 10 to 40 nm, even more preferably 10 to 30 nm.

The shape of component (A) may be, for example, spherical, flaky, rod-like, spindle-like, needle-like, or irregular, but any shape can be used so long as the average primary particle size is within the above range.
The average primary particle size of component (A) in the present invention can be determined from an image observed by a transmission electron microscope (TEM). Specifically, the TEM is used to observe the particles at a magnification of 50,000 times, and the maximum short diameter of 300 primary particles in the observed image is measured, and the number average value is calculated. Here, the maximum short diameter means the short diameter having the maximum length among the short diameters perpendicular to the long diameter when component (A) has a shape other than a flaky shape. When component (A) has a flaky shape, the thickness of 300 primary particles in the observed image observed under the same conditions as above is measured, and the number average value is calculated. Specifically, the thickness is measured by the method described in the examples.

Examples of the hydrophobization treatment of component (A) include silicone treatment; alkylalkoxysilane treatment; fatty acid treatment; fluorine-containing compound treatment such as perfluoroalkyl phosphate ester, perfluoroalcohol, etc.; amino acid treatment such as N-acylglutamic acid, etc.; lecithin treatment; metal soap treatment; alkyl phosphate ester treatment; and ASI treatment using N-acylamino acid metal salt (sodium lauroyl aspartate), zinc chloride, and alkoxytitanium alkylate (isopropyl titanium triisostearate).
These surface treatments may be used alone or in combination of two or more.
Among these, from the viewpoint of increasing the content of fine particle metal oxide in the emulsified cosmetic, improving the ultraviolet protection effect, emulsion stability, and good spreadability upon application, as well as suppressing the dry feeling and stickiness after application, preferably, one or more treatments are selected from the group consisting of silicone treatment, alkylalkoxysilane treatment, and fatty acid treatment.

Examples of surface treatment agents used in silicone treatment include various silicone oils such as methylpolysiloxane, dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, methylcyclopolysiloxane, dodecamethylcyclohexasiloxane, tetradecamethylhexasiloxane, dimethylsiloxane/methyl(polyoxyethylene)siloxane/methyl(polyoxypropylene)siloxane copolymer, dimethylsiloxane/methyl(polyoxyethylene)siloxane copolymer, dimethylsiloxane/methyl(polyoxypropylene)siloxane copolymer, dimethylsiloxane/methylcetyloxysiloxane copolymer, dimethylsiloxane/methylstearoxysiloxane copolymer, and (alkyl acrylate/dimethicone) copolymer. Among these, methylhydrogenpolysiloxane and dimethylpolysiloxane are preferred from the viewpoints of increasing the dispersibility of component (A) in the emulsified cosmetic, improving the UV protection effect, emulsion stability, and good spreadability upon application, as well as suppressing the dry feeling and stickiness after application.

From the viewpoints of increasing the dispersibility of component (A) in the emulsified cosmetic, improving the UV protection effect, emulsion stability, and spreadability upon application, as well as suppressing the dry feeling and stickiness after application, the surface treatment agent used in the alkylalkoxysilane treatment is preferably one having a linear or branched alkyl group having 6 to 20 carbon atoms, and more preferably octyltriethoxysilane or octyltrimethoxysilane.

Examples of the surface treatment agent used in the fatty acid treatment include linear or branched higher fatty acids having from 12 to 22 carbon atoms. Among these, from the viewpoints of increasing the dispersibility of component (A) in the emulsion cosmetic, improving the UV protection effect, emulsion stability, and spreadability upon application, and suppressing the dry feeling and stickiness after application, linear or branched higher fatty acids having from 14 to 22 carbon atoms are preferred, linear or branched higher fatty acids having from 16 to 20 carbon atoms are more preferred, and stearic acid and isostearic acid are even more preferred.
The above-mentioned surface treatment agents may be used alone or in combination of two or more.

Commercially available hydrophobically treated zinc oxide particles include the FINEX series (manufactured by Sakai Chemical Industry Co., Ltd.), the MZ series, and the MZY series (all manufactured by Teika Corporation).
Commercially available hydrophobically treated titanium dioxide particles include the STR series (manufactured by Sakai Chemical Industry Co., Ltd.), the TTO-55 series, the TTO-51 series (all manufactured by Ishihara Sangyo Kaisha, Ltd.), the MT series, and the MTY series (all manufactured by Teika Corporation).

The amount of the hydrophobization treatment in component (A) is, from the viewpoints of increasing the dispersibility of component (A) in the emulsified cosmetic and improving the UV protection effect, emulsion stability, and spreadability upon application, as well as suppressing the dry feeling and stickiness after application, preferably 0.1% by mass or more and preferably 40% by mass or less, more preferably 30% by mass or less, relative to component (A).
In the present invention, the mass and average primary particle size of component (A) mean the mass and average primary particle size including the surface treatment agent.

The content of component (A) in the emulsion cosmetic of the present invention is 7% by mass or more, preferably 9% by mass or more, more preferably 10% by mass or more, and even more preferably 13% by mass or more, from the viewpoint of enhancing the ultraviolet protection effect, and is 30% by mass or less, preferably 27% by mass or less, more preferably 25% by mass or less, even more preferably 23% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of improving the emulsion stability and suppressing the dry feeling. More specifically, from the viewpoint of enhancing the ultraviolet protection effect, improving the emulsion stability, and suppressing the dry feeling, the content is preferably 9 to 27% by mass, more preferably 10 to 25% by mass, even more preferably 10 to 23% by mass, and even more preferably 13 to 20% by mass.

From the viewpoint of transparency when applied to the skin, component (A) preferably contains hydrophobized fine zinc oxide.When component (A) contains hydrophobized fine zinc oxide, the content of hydrophobized fine zinc oxide in component (A) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more, from the same viewpoint as above.
From the viewpoint of ultraviolet protection effect, component (A) preferably contains hydrophobized fine particle titanium dioxide. When component (A) contains hydrophobized fine particle titanium dioxide, the content of hydrophobized fine particle titanium dioxide in component (A) is preferably 50 mass% or more, more preferably 55 mass% or more, even more preferably 60 mass% or more, and even more preferably 65 mass% or more from the same viewpoint as above.

<Component (B): Sterol Ester>
The oil-in-water emulsion cosmetic of the present invention contains a sterol ester as component (B).
Examples of sterols constituting the sterol ester include animal sterols such as cholesterol, lanosterol, dihydrocholesterol, cholestanol, coprostanol, epicoprosterol, epicoprostanol, 22-dehydrocholesterol, desmosterol, 24-methylenecholesterol, 24,25-dihydrolanosterol, norlanosterol, spinasterol, dihydroagnosterol, agnosterol, lophenol, and lathosterol; campesterol, campestanol, brassicasterol, 22-dehydrocampesterol, stigmasterol, stigmastanol, β-sitosterol, and the like. Examples of sterols include plant sterols (phytosterols) such as sterol, 22-dihydrospinasterol, 22-dehydrostigmastanol, 7-dehydrostigmasterol, tirucallol, euhol, fucosterol, isofucosterol, kodysterol, clionasterol, poriferasterol, clerosterol, 22-dehydroclerosterol, fungisterol, chondrilasterol, avenasterol, vernosterol, and polinastanol; and fungal sterols such as ergosterol, dehydroergosterol, 22,23-dihydroergosterol, episterol, ascosterol, and fecosterol.
Among these, the sterol constituting the sterol ester of component (B) preferably contains one or more sterols selected from the group consisting of cholesterol and phytosterols, from the viewpoint of suppressing a dry feeling after application.

From the viewpoint of suppressing the dry feeling after application, the sterol ester of component (B) is preferably one or more selected from the group consisting of sterol fatty acid esters, acylamino acid sterol/higher alcohol esters, and dimer dilinoleic acid sterol/higher alcohol esters.

From the viewpoint of suppressing a dry feeling after application, the cholesterol ester is preferably one or more selected from the group consisting of cholesterol fatty acid esters and acylamino acid cholesterol/higher alcohol esters, and more preferably cholesterol fatty acid esters.

Examples of cholesterol fatty acid esters include cholesteryl macadamia nut oil fatty acid, cholesteryl hydroxystearate, cholesteryl lanolin fatty acid, branched fatty acid (C12-31) cholesteryl, cholesteryl stearate, cholesteryl isostearate, cholesteryl oleate, dihydrocholesteryl oleate, cholesteryl ricinoleate, and cholesteryl nonanoate.
Examples of acylamino acid cholesterol/higher alcohol esters include di(cholesteryl/behenyl/octyldodecyl) lauroyl glutamate, di(cholesteryl/octyldodecyl) lauroyl glutamate, and the like.

Commercially available cholesterol esters include, for example, "Ecolano CLE-S", "Ecolano CLE-H" (cholesteryl lanolate), "Ecolano CLE-NH" (cholesteryl branched fatty acid (C12-31)), "Ecolano LC-CN" (cholesteryl nonanoate), and "Ecolano-MAC" (cholesteryl macadamiate) (all manufactured by Nippon Fine Chemicals Co., Ltd.); "Eldew CL-301" (cholesteryl/behenyl/octyldodecyl lauroyl glutamate), "Eldew CL-202" (cholesteryl/octyldodecyl lauroyl glutamate) (all manufactured by Ajinomoto Co., Inc.); and "Salacos HS" (cholesteryl hydroxystearate) (manufactured by Nisshin Oillio Group, Ltd.).

From the viewpoint of suppressing the dry feeling after application, the phytosterol ester is preferably one or more selected from the group consisting of phytosterol fatty acid esters, acylamino acid phytosterol/higher alcohol esters, and dimer dilinoleic acid phytosterol/higher alcohol esters.

Phytosterol fatty acid esters include phytosteryl macadamia nut oil fatty acid, phytosteryl lanolin fatty acid, phytosteryl stearate, phytosteryl isostearate, phytosteryl hydroxystearate, phytosteryl oleate, dihydrophytosteryl oleate, phytosteryl ricinoleate, phytosteryl nonanoate, phytosteryl rice bran oil fatty acid, phytosteryl palmitate, phytosteryl 2-ethylhexanoate, phytosteryl caprate, phytosteryl laurate, and phytosteryl butyrate.

Examples of acylamino acid phytosterol/higher alcohol esters include di(phytosteryl/octyldodecyl) lauroyl glutamate, di(octyldodecyl/phytosteryl/behenyl) lauroyl glutamate, and myristoyl methyl-β-alanine (phytosteryl/decyltetradecyl).

Examples of phytosterol/higher alcohol esters of dimer dilinoleic acid include dimer dilinoleic acid (phytosteryl/behenyl), dimer dilinoleic acid (phytosteryl/isostearyl/cetyl/stearyl/behenyl), dimer dilinoleyl bis(behenyl/isostearyl/phytosteryl) dimer dilinoleic acid, and di(isostearyl/phytosteryl) dimer dilinoleic acid.

Commercially available phytosterol esters include, for example, "Plandool-MAS" (phytosteryl macadamiate), "Plandool-ISS" (phytosteryl isostearate), "Plandool-S", "Plandool-H" (phytosteryl/isostearyl/cetyl/stearyl/behenyl dimer dilinoleate), "Plandool-G" (dimer dilinoleate Irbis (behenyl/isostearyl/phytosteryl)), "Plandool-SUN" (phytosteryl oleate), "Plandool-LG1", "Plandool-LG3", "Plandool-LG4" (di(octyldodecyl/phytosteryl/behenyl) lauroyl glutamate), "Plandool-LG2" (di(phytosteryl/octyldodecyl) lauroyl glutamate), "LUSPLAN PI-DA" (di(isostearyl/phytosteryl) dimer dilinoleate) (all manufactured by Nippon Fine Chemicals Co., Ltd.); "ELDEW PS-203" (di(phytosteryl/octyldodecyl) lauroyl glutamate), "ELDEW PS-304", "ELDEW PS-306" (di(octyldodecyl/phytosteryl/behenyl) lauroyl glutamate), "ELDEW APS-307" (phytosteryl/decyltetradecyl myristoyl methyl-β-alanine) (all manufactured by Ajinomoto Co., Inc.); "SALACOS FH" (phytosteryl hydroxystearate), "SALACOS PO(T)" (phytosteryl oleate) (all manufactured by Nisshin Oillio Group, Ltd.).

From the viewpoint of suppressing a dry feeling after application, component (B) is preferably a sterol fatty acid ester, more preferably one or more selected from the group consisting of cholesterol fatty acid esters and phytosterol fatty acid esters, and even more preferably one or more selected from the group consisting of branched fatty acid (C12-31) cholesteryl and macadamia nut oil fatty acid phytosteryl.

The content of component (B) in the emulsion cosmetic of the present invention is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, from the viewpoint of suppressing a dry feeling after application, and is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 5% by mass or less, and even more preferably 3% by mass or less, from the viewpoint of improving emulsion stability and spreadability during application and suppressing stickiness after application. More specifically, it is preferably 0.3 to 10% by mass, more preferably 0.5 to 7% by mass, even more preferably 1 to 5% by mass, and even more preferably 1 to 3% by mass.

The mass ratio of component (A) to component (B) in the emulsion cosmetic of the present invention [(A)/(B)] is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and even more preferably 6 or more, from the viewpoint of improving emulsion stability and spreadability upon application and suppressing stickiness after application, and is preferably 30 or less, more preferably 20 or less, even more preferably 15 or less, even more preferably 10 or less, and even more preferably 9 or less, from the viewpoint of suppressing a dry feeling after application. More specifically, it is preferably 3 to 30, more preferably 3 to 20, even more preferably 4 to 15, even more preferably 5 to 10, and even more preferably 6 to 9.

The oil-in-water emulsion cosmetic of the present invention may contain, in addition to components (A) and (B), optional components used according to the intended use of the cosmetic, as appropriate, to the extent that the effects of the present invention are not impaired. Examples of such optional components include ultraviolet absorbers, oils, surfactants, water-soluble polymers, neutralizing agents, pH adjusters, bactericides, anti-inflammatory agents, preservatives, colorants, chelating agents, whitening agents, antiperspirants, antioxidants, fragrances, etc., other than components (A) and (B).

<Component (C): Ultraviolet Absorber>
The oil-in-water emulsion cosmetic of the present invention may contain an ultraviolet absorber as component (C) to the extent that the effects of the present invention are not impaired. Examples of the ultraviolet absorber include one or more organic ultraviolet absorbers selected from the group consisting of liquid organic ultraviolet absorbers and solid organic ultraviolet absorbers.
In this specification, "liquid" refers to a state having fluidity under an environment of 1 atmosphere and 25°C, i.e., a state under temperature conditions of the melting point or higher (in the case of an amorphous substance having no melting point, a state under temperature conditions of the melting point or higher). Also, "solid" refers to a state not having fluidity under an environment of 1 atmosphere and 25°C, i.e., a state under temperature conditions below the melting point (in the case of an amorphous substance having no melting point, a state under temperature conditions below the melting point).

Examples of liquid organic UV absorbers include 2-ethylhexyl paramethoxycinnamate, 2-ethoxyethyl paramethoxycinnamate, a mixture of isopropyl paramethoxycinnamate and diisopropyl cinnamate, methyl bis(trimethylsiloxy)silylisopentyl trimethoxycinnamate, amyl paradimethylamino acid benzoate, 2-ethylhexyl paradimethylamino acid benzoate, ethylene glycol salicylate, 2-ethylhexyl salicylate, benzyl salicylate, homomenthyl salicylate, octocrylene, and dimethicodimethyi benzalmalonate.

Examples of solid organic UV absorbers include 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid hexyl ester, 2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine, 4-tert-butyl-4'-methoxydibenzoylmethane, and 2-ethylhexyl dimethoxybenzylidene dioxoimidazolidinepropionate.

Commercially available products of these UV absorbers include, for example, "UVINUL MC80" (2-ethylhexyl paramethoxycinnamate), "UVINUL A PLUS" (2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid hexyl ester), "TINOSORB S" (2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazine), and "UVINUL T-150" (2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine) (all manufactured by BASF); "Soft Shade DH" (2-ethylhexyl dimethoxybenzylidene dioxoimidazolidinepropionate) (manufactured by Ajinomoto Co., Inc.); and "PARSOL 1789" (4-tert-butyl-4'-methoxydibenzoylmethane), and PARSOL SLX (Polysilicone-15 (dimethicone diethyl benzalmalonate)) (both manufactured by DSM).

From the viewpoint of reducing the burden on the skin, the content of component (C) in the emulsion cosmetic of the present invention is preferably less than 3 mass%, more preferably less than 2 mass%, even more preferably less than 1 mass%, still more preferably less than 0.5 mass%, and even more preferably 0 mass%, i.e., no component (C) is contained.
Even if the content of component (C) is within the above-mentioned range, the emulsion cosmetic of the present invention can exhibit the effects of having an excellent ultraviolet protection effect, excellent emulsion stability, good spreadability upon application, and an excellent feel upon use with reduced dryness and stickiness after application. From this viewpoint, the emulsion cosmetic of the present invention can be applied to non-chemical sunscreen cosmetics that do not contain organic ultraviolet absorbers, which have attracted attention in recent years as cosmetics that are gentle on the skin.

<Component (D): Oil other than components (B) and (C)>
From the viewpoint of incorporating component (A) and improving emulsion stability, the oil-in-water emulsion cosmetic of the present invention preferably further contains an oil agent other than components (B) and (C) as component (D).
Component (D) is preferably a non-volatile oil, and examples of such oil include ester oil, silicone oil, hydrocarbon oil, higher alcohol, and higher fatty acid.
The non-volatile oil may be liquid or solid at 25° C., and preferably includes one that is liquid at 25° C. The terms “liquid” and “solid” are defined above.
In this specification, the term "non-volatile" means that the amount of evaporation at 25° C. for 6 hours is less than 20%, as measured by the following method.
Measurement method: A 90 mm diameter filter paper is placed in a 120 mm diameter glass petri dish, 1 g of the sample is placed on the filter paper, and stored in a room at 65% RH (25°C) for 6 hours. The mass of the sample before and after storage is measured, and the amount of evaporation is calculated using the following formula.
Evaporation amount (%)=(sample mass before storage−sample mass after storage)/sample mass before storage×100

Examples of non-volatile liquid ester oils include isononyl isononanoate, isotridecyl isononanoate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isopropyl palmitate, ethylhexyl palmitate, 2-hexyldecyl palmitate, glyceryl tri-2-ethylhexanoate, di-2-ethylhexyl sebacate, diisopropyl sebacate, tri(caprylic acid/capric acid)glyceryl, diisostearyl malate, diethylene glycol dicaprate, neopentyl glycol dicaprate, neopentyl glycol di-2-ethylhexanoate, and one or more selected from the group consisting of alkyl benzoates such as alkyl benzoates (C12-15).

Among the above, from the viewpoint of incorporating component (A) and improving emulsion stability, the non-volatile liquid ester oil is preferably one or more selected from the group consisting of a monoester of a branched fatty acid having 8 to 18 carbon atoms and a branched alcohol having 2 to 22 carbon atoms, a triester of a branched fatty acid having 6 to 18 carbon atoms and glycerin, a diester of a dicarboxylic acid having 2 to 18 carbon atoms and a branched alcohol having 2 to 18 carbon atoms, a diester of a fatty acid having 6 to 18 carbon atoms and a branched dialcohol having 2 to 10 carbon atoms, and an alkyl benzoate (C12-15) (e.g., "Finsorb TN" (manufactured by Innospec Active Chemicals LLC)), more preferably a monoester of a branched fatty acid having 8 to 18 carbon atoms and a branched alcohol having 2 to 22 carbon atoms, and even more preferably one or more selected from the group consisting of isononyl isononanoate and isotridecyl isononanoate.

From the viewpoint of incorporating component (A) and achieving good emulsion stability, the non-volatile liquid silicone oil is preferably a dimethylpolysiloxane, and more preferably a dimethylpolysiloxane having a kinetic viscosity at 25° C. of 20 mm ² /s or less.
The kinetic viscosity of the silicone oil at 25° C. can be measured by an Ubbelohde viscometer in accordance with ASTM D 445-46T or JIS Z 8803.

Non-volatile liquid hydrocarbon oils include liquid paraffin, hydrogenated polyisobutene (liquid isoparaffin, heavy liquid isoparaffin), cycloparaffin, liquid ozokerite, squalene, squalane, pristane, α-olefin oligomer, polybutene, isohexadecane, etc.

Examples of non-volatile liquid higher alcohols include higher alcohols having 12 to 24 carbon atoms, and specific examples thereof include oleyl alcohol, 2-decyltetradecyl alcohol, dodecanol, isostearyl alcohol, and 2-octyldodecanol.
Examples of non-volatile liquid higher fatty acids include fatty acids having 12 to 22 carbon atoms, and specific examples thereof include oleic acid, isostearic acid, linoleic acid, and linolenic acid.

In the present invention, from the viewpoint of improving emulsion stability, it is preferable that the non-volatile oil used as component (D) further contains a non-volatile oil that is solid at 25°C.
Examples of non-volatile oils that are solid at 25° C. include solid ester oils such as glyceryl monostearate and glyceryl monomyristate; solid silicone oils such as alkyl-modified silicone; solid hydrocarbon oils such as petrolatum; solid higher alcohols such as cetyl alcohol, stearyl alcohol, and behenyl alcohol; and solid higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, and lanolin fatty acid.

Of these, from the viewpoint of incorporating component (A) and improving emulsion stability, component (D) is preferably at least one selected from the group consisting of ester oils, silicone oils, and higher alcohols.
The above oil agents may be contained alone or in combination of two or more.

The content of component (D) in the emulsion cosmetic of the present invention is, from the viewpoint of incorporating component (A) and improving emulsion stability, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 17% by mass or more, and preferably 30% by mass or less, more preferably 27% by mass or less, even more preferably 25% by mass or less. More specifically, it is preferably 5 to 30% by mass, more preferably 10 to 27% by mass, even more preferably 15 to 25% by mass, even more preferably 17 to 25% by mass.

<Component (E): Surfactant>
From the viewpoint of improving emulsion stability and usability, the oil-in-water emulsion cosmetic of the present invention preferably further contains a surfactant as component (E). Component (E) is not particularly limited, and examples thereof include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.
The component (E) may be contained alone or in combination of two or more kinds.

From the viewpoints of improving emulsion stability and usability, the component (E) is preferably an amphoteric surfactant.
Examples of amphoteric surfactants include betaine type surfactants, amine oxide type surfactants, amino acid type surfactants, etc. Among these, betaine type surfactants are preferred from the viewpoints of improving emulsion stability and usability.
Examples of amphoteric surfactants include carboxybetaine types such as alkyldimethylaminoacetic acid betaine and fatty acid amidopropyl betaine; sulfobetaine types such as alkylsulfobetaine and alkylhydroxysulfobetaine; imidazoline betaine types such as alkylcarboxymethylhydroxyethylimidazolinium betaine; and phosphobetaine types such as lecithin, hydrogenated lecithin, and lauryl hydroxyphosphobetaine. Among these, phosphobetaine types are preferred, hydrogenated lecithin is more preferred, and hydrogenated soybean lecithin is even more preferred.

From the viewpoint of improving emulsion stability and usability, the content of component (E) in the emulsion cosmetic of the present invention is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less. More specifically, it is preferably 0.1 to 3% by mass, more preferably 0.1 to 2% by mass, and even more preferably 0.3 to 1% by mass.

<Component (F): Water-soluble polymer>
From the viewpoint of obtaining good emulsion stability, it is preferable that the oil-in-water cosmetic composition of the present invention further contains a water-soluble polymer having a thickening effect as component (F).
There are no limitations on component (F) so long as it is one that is commonly used in cosmetics, and any of natural polymers, semi-synthetic polymers, and synthetic polymers can be used.

Examples of natural polymers include xanthan gum, carrageenan, alginic acid, etc. Among them, xanthan gum is preferred from the viewpoint of obtaining good emulsion stability.
Examples of the semi-synthetic polymer include modified polysaccharides such as hydroxycellulose, hydroxypropylcellulose, sodium carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, and cationic cellulose.

Examples of synthetic polymers include acrylic polymers such as carbomer (crosslinked polyacrylic acid), polyacrylic acid, sodium polyacrylate, (acrylic acid/alkyl methacrylate) copolymer, polyacrylamide, (sodium acrylate/sodium acryloyldimethyltaurate) copolymer, (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymer, (beheneth-25 methacrylate/ammonium acryloyldimethyltaurate) cross copolymer, (lauryl methacrylate/laureth-4 methacrylate/ammonium acryloyldimethyltaurate/dimethylacrylamide) crosspolymer, (acrylamide/ammonium acrylate) copolymer, and polyacrylate-13; polyvinylpyrrolidone, polyvinyl alcohol, and cationized polyvinylpyrrolidone. Among these, from the viewpoint of obtaining good emulsion stability, preferred are acrylic polymers, and more preferred are carbomers, (acrylic acid/alkyl methacrylate) copolymers, polyacrylamides, (sodium acrylate/sodium acryloyldimethyltaurate) copolymers, (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymers, (beheneth-25 methacrylate/ammonium acryloyldimethyltaurate) cross copolymers, (lauryl methacrylate/laureth-4 methacrylate/ammonium acryloyldimethyltaurate/dimethylacrylamide) cross polymers, (acrylic acid/alkyl methacrylate) copolymers, polyacrylamides, (sodium acrylate/sodium acryloyldimethyltaurate) copolymers, (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) cross copolymers, (lauryl methacrylate/laureth-4 methacrylate/ammonium acryloyldimethyltaurate/dimethylacrylamide) cross polymers, (acrylic acid/alkyl methacrylate) copolymers, polyacrylamides, (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) cross copolymers ... It is preferably one or more selected from the group consisting of (sodium acrylate/sodium acryloyldimethyltaurate) copolymer, (beheneth-25 methacrylate/ammonium acryloyldimethyltaurate) cross copolymer, and (lauryl methacrylate/laureth-4 methacrylate/ammonium acryloyldimethyltaurate/dimethylacrylamide) crosspolymer, and even more preferably it is (sodium acrylate/sodium acryloyldimethyltaurate) copolymer.

Commercially available carbomer products include "Carbopol 910", "Carbopol 934", "Carbopol 940", "Carbopol 941", "Carbopol 980", and "Carbopol 981" (all manufactured by Lubrizol Advanced Materials).
Commercially available (acrylic acid/alkyl methacrylate) copolymers include "Carbopol 1382", "Carbopol ETD2020", "PEMULEN TR-1", and "PEMULEN TR-2" (all manufactured by Lubrizol Advanced Materials).
Commercially available polyacrylamide products include "SEPIGEL 305" (manufactured by SEPPIC Corporation).
Commercially available products of (sodium acrylate/sodium acryloyldimethyltaurate) copolymers include "SIMULGEL EG" (manufactured by SEPPIC Corporation).
Commercially available products of (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymers include "SIMULGEL FL", "SIMULGEL NS", "SEPIPLUS S", and "SEPINOV EMT 10" (all manufactured by SEPPIC Corporation).
Commercially available products of (beheneth-25 methacrylate/ammonium acryloyldimethyltaurate) cross copolymers include "ARISTOFLEX HMB" (manufactured by Clariant), and the like.
An example of a commercially available product of the (lauryl methacrylate/laureth-4 methacrylate/ammonium acryloyldimethyltaurate/dimethylacrylamide) crosspolymer is "SEPIMAX ZEN" (manufactured by SEPPIC Corporation).

The content of component (F) in the emulsion cosmetic of the present invention is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, from the viewpoint of obtaining good emulsion stability, and is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of improving the feeling of use. More specifically, it is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, and even more preferably 0.1 to 1% by mass.

(Aqueous medium)
The oil-in-water emulsion cosmetic of the present invention contains at least water as the aqueous medium.
Examples of aqueous media other than water include saturated monohydric alcohols having 1 to 3 carbon atoms, such as ethanol and isopropyl alcohol; and polyhydric alcohols, such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (average molecular weight less than 650), propylene glycol, dipropylene glycol, polypropylene glycol (average molecular weight less than 650), isoprene glycol, 1,3-butylene glycol, glycerin, diglycerin, and polyglycerin. Among these, polyhydric alcohols are preferred, and more preferred are one or more selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butylene glycol, and glycerin, and even more preferred are one or more selected from the group consisting of dipropylene glycol, 1,3-butylene glycol, and glycerin. These alcohols can be used alone or in combination of two or more.

The content of the aqueous medium in the emulsion cosmetic of the present invention may be within a range that allows it to become an oil-in-water cosmetic, and from the viewpoint of improving emulsion stability, it is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 47% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less. More specifically, it is preferably 40 to 90% by mass, more preferably 45 to 80% by mass, even more preferably 47 to 75% by mass.
When the emulsion cosmetic of the present invention contains a polyhydric alcohol, the content of the polyhydric alcohol in the emulsion cosmetic is, from the viewpoint of improving emulsion stability, preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less, even more preferably 4% by mass or less. More specifically, it is preferably 0.5 to 7% by mass, more preferably 1 to 5% by mass, even more preferably 2 to 4% by mass.

The emulsion cosmetic of the present invention can be suitably used as hair cosmetics such as shampoos, rinses, conditioners, etc., and skin cosmetics such as facial cleansers, cleansing cosmetics, sunscreen cosmetics, packs, massage cosmetics, etc. Among these, since the emulsion cosmetic of the present invention has excellent ultraviolet protection effect, it is preferable to apply it to sunscreen cosmetics (lotion, cream, milky lotion, serum, etc.), suntan, makeup base cosmetics, foundations, etc., for sunscreen purposes.
The emulsion cosmetic of the present invention can be in any form, such as liquid, emulsion, cream, paste, solid, multi-layer, etc., and can also be used as a sheet, spray, or mousse.

(Method for producing oil-in-water emulsion cosmetics)
The method for producing the oil-in-water emulsion cosmetic of the present invention is not particularly limited, and any known method can be used appropriately depending on the formulation of the oil-in-water emulsion cosmetic. For example, there is a method including a step of blending component (A), component (B), and, if necessary, the optional components described above, and mixing them uniformly using a homomixer or the like.

As a method for producing the emulsion cosmetic of the present invention, from the viewpoints of increasing the dispersibility of component (A) in the emulsion cosmetic, improving the UV protection effect, emulsion stability, and good spreadability upon application, and suppressing the dry feeling and stickiness after application, a method including a step of mixing and emulsifying a dispersion of component (A) in an oil phase component containing component (B) and, if necessary, the above-mentioned oil-soluble optional component, with an aqueous medium and, if necessary, a preparation of an aqueous phase component containing the above-mentioned water-soluble optional component, is more preferable, and a method including the following steps I to III is more preferable.
Step I: A step of adding component (A) to an oil phase component containing component (B) and, if necessary, the aforementioned optional oil-soluble component, and mixing uniformly to obtain a dispersion (i) in which component (A) is dispersed. Step II: A step of uniformly mixing an aqueous medium and, if necessary, an aqueous phase component containing the aforementioned optional water-soluble component to obtain a preparation (ii). Step III: A step of adding the dispersion (i) obtained in step I to the preparation (ii) obtained in step II, mixing uniformly, and emulsifying to obtain an oil-in-water emulsion cosmetic.

From the viewpoint of enhancing the dispersibility of component (A) in the emulsion cosmetic, step I preferably includes the following steps I-1 and I-2.
Step I-1: A step of uniformly mixing the oil phase components including the component (B) and, if necessary, the above-mentioned optional oil-soluble components to obtain a preparation (i'). Step I-2: A step of adding the component (A) to the preparation (i') obtained in step I-1, uniformly mixing, and obtaining a dispersion (i) in which the component (A) is dispersed.

The mixing of the oil phase components in step I-1 and the mixing of the aqueous phase components in step II are preferably carried out with stirring while heating at a temperature in the range of 40° C. or higher and 90° C. or lower.
In step II, preparation (ii) is preferably obtained by cooling to a temperature range of 15° C. or more and 35° C. or less, and then further mixing uniformly.
In step III, it is preferable to add the dispersion (i) obtained in step I while stirring the preparation (ii) obtained in step II, preferably maintaining the temperature at 40°C or higher and 90°C or lower, and mix and emulsify uniformly.

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

(Average primary particle size of component (A))
The average primary particle size of component (A) was measured by the following method.
When the measurement sample has a shape other than a plate shape, a dispersion of the measurement sample prepared in advance was placed on the sample stage of a transmission electron microscope (TEM) (trade name "JEM1400Plus", manufactured by JEOL Ltd.) and air-dried, and the maximum short diameters of 300 primary particles in an image observed under conditions of observation magnification of 50,000 times with the TEM were measured, and the number average value was taken as the average primary particle diameter. Here, the maximum short diameter means the short diameter having the longest length among the short diameters perpendicular to the long diameter.
When the measurement sample had a plate-like shape, the thicknesses of 300 primary particles in an image observed under the same method and magnification conditions as above were measured, and the number average value was taken as the average primary particle diameter of each.
The dispersion of the measurement sample was prepared by adding 95 g of ethanol as a solvent to 5 g of the measurement sample and subjecting the mixture to ultrasonic dispersion.

Examples 1 to 7, Comparative Examples 1 to 5
According to the formulations shown in Table 1, each oil-in-water emulsion cosmetic was obtained by the following method.
Components 5 to 12 shown in Table 1 were mixed uniformly, heated to 80°C, and dissolved to obtain preparation (i') (step I-1). Next, while maintaining the obtained preparation (i') at 80°C, components 1 to 4 shown in Table 1 were added, mixed uniformly, and dispersed to obtain dispersion (i) (step I-2).
Separately, ingredients 13 to 17 shown in Table 1 were heated to 40°C, dissolved, and naturally cooled to 25°C, and then mixed uniformly to obtain preparation (ii) (Step II).
While stirring the obtained preparation (ii), the dispersion (i) kept at 80° C. was added, and the mixture was uniformly mixed and emulsified using a homomixer to obtain an oil-in-water emulsion cosmetic (Step III).

The obtained oil-in-water emulsion cosmetic was evaluated for (1) UV protection ability, (2) emulsion stability, and (3) usability (ease of spreading when applied, lack of dryness after application, lack of stickiness after application). The results are shown in Table 1.

(1) UV protection ability The oil-in-water emulsion cosmetic composition shown in Table 1 was uniformly applied to a square PMMA plate ("HD6" manufactured by HelioScreen) at a coating amount of 1.3 mg/ ^cm2 and dried for 15 minutes to prepare a measurement sample. Similarly, glycerin was applied to a PMMA plate and dried for 15 minutes to prepare a control sample. The in vitro SPF value was calculated from the measurement results of the absorption spectrum (measurement wavelength 290-450 nm) using an SPF analyzer "UV-2000S" (manufactured by Labsphere), and the average of the in vitro SPF values at nine points of each sample was taken as the UV protection ability (SPF value).

(2) Emulsion Stability The appearance of the oil-in-water emulsion cosmetic compositions shown in Table 1 was visually observed immediately after preparation and after storage at 40° C. for one month, and judged according to the following criteria.
〔Judgment criteria〕
A: No separation or gelation was observed immediately after preparation of the cosmetic preparation, and no separation or gelation was observed even after storage at 40°C for one month.
B: No separation or gelation was observed immediately after preparation of the cosmetic preparation, but slight separation or gelation was observed after storage at 40°C for one month.
C: No separation or gelation was observed immediately after preparation of the cosmetic preparation, but obvious separation or gelation was observed after storage at 40°C for one month.
D: Separation or gelation was observed immediately after preparation of the cosmetic preparation.

(3) Feel when used (good spreadability when applied, no dry feeling after application, no stickiness after application)
Ten expert panelists used the oil-in-water emulsion cosmetics shown in Table 1. At 25°C and 57% RH, 0.02 mL of each oil-in-water emulsion cosmetic was applied to the inside of the forearm in a circle of 3 cm in diameter, and the cosmetic was spread over a period of 1 minute. The sensation of use after spreading was evaluated based on the following criteria: "good spreadability upon application,""absence of dry feeling after application," and "absence of stickiness after application." Each was judged based on the following criteria from the average value of the 10 panelists.
Moreover, when the transparency after spreading was visually confirmed, Examples 1 to 3 had higher transparency than Example 4.
〔Evaluation criteria〕
5 points: Very good 4 points: Good 3 points: Average 2 points: Slightly poor 1 point: Poor [Judgment criteria]
A: 4.0 points or more and 5.0 points or less B: 3.0 points or more and less than 4.0 points C: 2.0 points or more and less than 3.0 points D: 1.0 points or more and less than 2.0 points

Details of the components used in Table 1 are shown below.
*1: "MZY-303M2O" manufactured by Teika Corporation (hydrophobized zinc oxide fine particles, average primary particle diameter 30 nm)
*2: Sakai Chemical Industry Co., Ltd. "STR-100W-OTS" (hydrophobized fine titanium oxide particles, average primary particle diameter 10 nm)
*3: "BCASI TIO2 MP-701" manufactured by Daito Kasei Kogyo Co., Ltd. (hydrophobic treated pigment-grade titanium dioxide, average primary particle diameter 270 nm)
*4: Sakai Chemical Industry Co., Ltd. "STR-100W (G)" (hydrophilic treated titanium oxide fine particle, average primary particle diameter 10 nm)
*5: "Ecolano CLE-NH" manufactured by Nippon Fine Chemicals Co., Ltd.
*6: "Plandool-MAS" manufactured by Nippon Fine Chemicals Co., Ltd.
*7: "KF-96A-20CS" manufactured by Shin-Etsu Chemical Co., Ltd.
*8: "KF-96A-6CS" manufactured by Shin-Etsu Chemical Co., Ltd.
*9: "PhosphoLipid PCSH70" manufactured by Nippon Fine Chemical Co., Ltd.
* 10: SEPPIC "SIMULGEL EG" ((Sodium acrylate / sodium acryloyldimethyltaurate) copolymer, active content 37.5% by mass)

It can be seen from Table 1 that the oil-in-water emulsion cosmetics according to the examples of the present invention have superior UV protection ability, excellent emulsion stability, good spreadability upon application, and suppressed dryness and stickiness after application, compared to the oil-in-water emulsion cosmetics of the comparative examples.
In Comparative Example 1, the content of component (A) in the oil-in-water emulsion cosmetic is less than 7% by mass, so the UV protection effect is low and stickiness after application is not sufficiently suppressed.
In Comparative Example 2, since hydrophobically treated pigment-grade titanium oxide is used as the metal oxide powder, the ultraviolet protection effect is low and the emulsion stability is insufficient.
In Comparative Example 3, hydrophilically treated fine particle titanium dioxide was used as the metal oxide powder, and therefore the UV protection effect was low, the emulsion stability and spreadability upon application were insufficient, and the dry feeling and stickiness after application were not sufficiently suppressed.
In Comparative Examples 4 and 5, the oil-in-water emulsion cosmetic composition does not contain a sterol ester, and therefore the dry feeling after application is not sufficiently suppressed.

Claims (8)

An oil-in-water emulsion cosmetic comprising the following components (A) and (B):
Component (A): A hydrophobized fine particle metal oxide having an average primary particle diameter of less than 100 nm; Component (B): A sterol ester; The content of component (A) is 7% by mass or more and 30% by mass or less ,
The content of the ultraviolet absorber as component (C) is 0% by mass or more and less than 3% by mass,
The composition further contains an oil other than the components (B) and (C) as a component (D), a surfactant as a component (E), and a water-soluble polymer as a component (F),
The content of component (D) is 15% by mass or more and 30% by mass or less.
An oil-in-water emulsion cosmetic , comprising: a component (F) content of 0.1% by mass or more and 5% by mass or less . 2. The oil-in-water emulsion cosmetic according to claim 1 , wherein the content mass ratio of component (A) to component (B) [(A)/(B)] is 3 or more and 30 or less. 3. The oil-in-water emulsion cosmetic according to claim 1 , wherein the component (B) is at least one member selected from the group consisting of cholesterol fatty acid esters and phytosterol fatty acid esters. 4. The oil-in-water emulsion cosmetic according to claim 1 , wherein the metal oxide of component (A) is at least one selected from the group consisting of zinc oxide and titanium oxide. 5. The oil-in-water emulsion cosmetic according to claim 1 , wherein the hydrophobization treatment of component (A) is one or more treatments selected from the group consisting of silicone treatment, alkylalkoxysilane treatment, and fatty acid treatment. 6. The oil-in-water emulsion cosmetic according to any one of claims 1 to 5, wherein component (D) contains a non-volatile oil that is liquid at 25°C, and the liquid non-volatile oil contains one or more oils selected from the group consisting of ester oils, silicone oils, hydrocarbon oils, higher alcohols, and higher fatty acids. 7. The oil-in-water emulsion cosmetic according to any one of claims 1 to 6, wherein component (F) comprises a synthetic polymer, and the synthetic polymer is at least one selected from the group consisting of (sodium acrylate/sodium acryloyldimethyltaurate) copolymer, (beheneth-25 methacrylate/ammonium acryloyldimethyltaurate) cross copolymer, and (lauryl methacrylate/laureth-4 methacrylate/ammonium acryloyldimethyltaurate/dimethylacrylamide) crosspolymer. The oil-in-water emulsion cosmetic according to any one of claims 1 to 7 , which is used for sunscreen purposes.