Oil-in-water emulsion composition

Abstract

The present invention provides an oil-in-water emulsion composition that, when applied to the skin, exhibits moisture retaining properties and gives a feeling of moisture retention, exhibits an excellent ultraviolet protection effect, hardly forms powder residues, and can suppress a stimulus provided when the surface of a portion to which the composition has been applied is rubbed.　The present invention relates to an oil-in-water emulsion composition containing: core-shell particles in which a core part contains components (a1) and (a2), the component (a1) being a hydrophobized ultraviolet-scattering agent, the component (a2) being an oil solution that is in a liquid state at 25°C, and a shell part contains components (b1) and (b2), the component (b1) being an anionic surfactant, the component (b2) being a hydrophobic amphiphilic substance; (e1) a second hydrophobized ultraviolet-scattering agent; and (c4) an aqueous thickener. The core-shell particles and the (e1) second hydrophobized ultraviolet-scattering agent are dispersed.

Description

Oil-in-water emulsion composition

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

[0002] Sunburn caused by ultraviolet rays causes skin browning, loss of skin elasticity, and wrinkles, etc., so in order to achieve ultraviolet protection, sunscreen cosmetics usually contain ultraviolet absorbers and ultraviolet scattering agents. As examples of sunscreen cosmetics that use ultraviolet absorbers, specific sunscreen cosmetics containing α-gel particles encapsulating an oil-soluble ultraviolet absorber are known (Patent Documents 1 and 2).

[0003] (Patent Document 1) JP 2017-7969 A (Patent Document 2) JP 2020-63239 A (Patent Document 3) JP 2022-186915 A (Patent Document 4) JP 2022-117486 A (Patent Document 5) WO2023 / 286780

[0004] The present invention relates to an oil-in-water emulsion composition comprising core-shell particles whose core portion contains the following components (a1) and (a2): (a1) a hydrophobized UV scattering agent, and (a2) an oil agent that is liquid at 25°C, and whose shell portion contains the following components (b1) and (b2): (b1) an anionic surfactant, and (b2) a hydrophobic amphiphilic substance; (e1) a second hydrophobized UV scattering agent; and (c4) an aqueous thickener, in which the core-shell particles and (e1) the second hydrophobized UV scattering agent are dispersed.

[0005] 1 is a scanning electron microscope (SEM) image of the cross section of a core-shell particle obtained in Example 3. 2 is a diagram showing the cross section and average film thickness of the coating film of the oil-in-water sunscreen cosmetic of Example 3. 3 is a diagram showing the cross section and average film thickness of the coating film of the oil-in-water sunscreen cosmetic of Comparative Example 1. Detailed Description of the Invention

[0006] In recent years, due to the demand for cosmetics that are gentler on the skin, non-chemical sunscreen cosmetics that do not contain UV absorbers have attracted attention. To achieve high UV protection without UV absorbers, it is necessary to increase the content of UV scattering agents in sunscreen cosmetics. One such cosmetic is a water-in-oil sunscreen cosmetic that contains a total of approximately 25% by weight of a combination of hydrophobized zinc oxide particles and hydrophobized titanium oxide particles as hydrophobized UV scattering agents, along with a water-soluble polymer compound and spherical powder (Patent Document 3). Another reported example is a specific oil-in-water sunscreen cosmetic that contains 10 to 20% by weight of titanium oxide that has been hydrophobized with an aluminum-based surface treatment agent in addition to a (sodium acrylate / sodium acryloyldimethyltaurate) copolymer or a (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer and an oily compound (Patent Document 4). Furthermore, as a technique for suppressing white cast, it has been proposed to prepare an oil-in-water sunscreen cosmetic using an oil component mainly composed of polar oil, a specific amount of a hydrophobized UV scattering agent, and polyhydroxystearic acid (Patent Document 5). However, when the content of the hydrophobized UV scattering agent is increased as in the cosmetics described in Patent Documents 3 to 5, particularly when the content of the hydrophobized UV scattering agent is increased in non-chemical oil-in-water sunscreen cosmetics, the oil droplets spread thinly upon application, causing the hydrophobized UV scattering agent to aggregate on the skin, which is likely to cause white cast. Furthermore, there have been problems such as the possibility of phase inversion, or the aggregation easily causing uneven distribution of the hydrophobized UV scattering agent, which may result in insufficient UV protection effect.

[0007] The present invention relates to an oil-in-water emulsion composition that, when applied to the skin, exhibits moisturizing properties and provides a moisturizing feeling, exhibits excellent ultraviolet protection effect, is less likely to cause white cast, and can suppress irritation when the surface of the applied area is rubbed.

[0008] The present inventors have discovered that an oil-in-water emulsion composition comprising core-shell particles containing a hydrophobized UV scattering agent and an oil that is liquid at 25°C in the core portion, and an anionic surfactant and a hydrophobic amphiphilic substance in the shell portion, and a second hydrophobized UV scattering agent and an aqueous thickener outside the core-shell particles, in which the core-shell particles and the second hydrophobized UV scattering agent are dispersed, exhibits moisturizing properties and a moisturizing feel when applied to the skin, exhibits excellent UV protection effect, is less likely to cause white cast, and can suppress irritation when the surface of the applied area is rubbed, thereby completing the present invention.

[0009] The oil-in-water emulsion composition of the present invention exhibits moisturizing properties and provides a moisturizing feeling when applied to the skin, exhibits excellent UV protection effects, is less likely to cause white cast, and can suppress irritation when the surface of the applied area is rubbed.

[0010] [Core-shell Particles] The core-shell particles used in the present invention have a core portion containing the following components (a1) and (a2): (a1) a hydrophobized ultraviolet scattering agent, and (a2) an oil solution that is liquid at 25°C, and a shell portion containing the following components (b1) and (b2): (b1) an anionic surfactant, and (b2) a hydrophobic amphiphilic substance.

[0011] In this specification, "core-shell particles" refer to particles having a core and a shell that encapsulates the core. The core-shell structure can be confirmed by observing the cross section of the particle with a scanning electron microscope (SEM). The oil-in-water emulsion composition of the present invention has the above-mentioned core-shell particles dispersed therein. The core-shell particles are dispersed in the aqueous phase of the oil-in-water emulsion composition. In this specification, "dispersed" also includes particles in which some or all of the particles or hydrophobic-treated UV scattering agent have settled, as long as they can be partially or completely redispersed by stirring or shaking.

[0012] ((a1) Hydrophobized UV Scattering Agent) By incorporating a hydrophobized UV scattering agent into the core portion of the core-shell particles, the UV protection effect is improved and white cast is less likely to occur when the composition is applied to the skin as an oil-in-water emulsion composition. As the hydrophobized UV scattering agent, a hydrophobized metal oxide fine particle is preferred. From the viewpoint of easy availability, the metal oxide used in the hydrophobized metal oxide fine particle is preferably one or more metal oxides selected from zinc oxide, titanium oxide, cerium oxide, iron oxide, and chromium oxide. Among these metal oxides, from the viewpoint of UV protection effect, one or more metal oxides selected from zinc oxide, titanium oxide, and cerium oxide are preferred, one or more metal oxides selected from zinc oxide and titanium oxide are more preferred, and titanium oxide is even more preferred. Furthermore, trace elements with a valence of +2 or more can be incorporated into the metal oxide fine particle, and metals such as iron, zirconium, calcium, manganese, magnesium, and yttrium can be incorporated into the metal oxide fine particle, either alone or in combination of two or more.

[0013] The shape of the "fine particle metal oxide" is not particularly limited, and examples thereof include spherical, plate-like, rod-like, spindle-like, needle-like, and irregular shapes. The average particle size of the "fine particle metal oxide" is preferably 0.01 μm or more, more preferably 0.012 μm or more, and even more preferably 0.015 μm or more, and is preferably 1 μm or less, more preferably 0.8 μm or less, and even more preferably 0.5 μm or less. The specific range of the average particle size is preferably 0.01 μm or more and 1 μm or less, more preferably 0.012 μm or more and 0.8 μm or less, and even more preferably 0.015 μm or more and 0.5 μm or less. The average particle size of the fine particle metal oxide means the average particle size measured by a laser diffraction / scattering method.

[0014] Commercially available examples of zinc oxide particles include FINEX-25, FINEX-30, FINEX-50, and FINEX-75 (manufactured by Sakai Chemical Industry Co., Ltd.), the MZ300 series, MZ500 series, and MZ700 series (manufactured by Teika Corporation), and ZnO-350 (manufactured by Sumitomo Osaka Cement Co., Ltd.). Commercially available examples of titanium oxide particles include the TTO-55 series and TTO-51 series (manufactured by Ishihara Sangyo Kaisha), the JR series, and the JA series (manufactured by Teika Corporation). As cerium oxide particles, for example, high-purity cerium sold by Nikki Co., Ltd. or Seimi Chemical Co., Ltd. may be used.

[0015] The hydrophobization treatment of the fine particle metal oxide may be carried out using a known surface treatment agent for hydrophobization, and examples thereof include fluorine compound treatment, silicone treatment, silicone resin treatment, pendant treatment, silane coupling agent treatment, titanium coupling agent treatment, oil treatment, N-acylated lysine treatment, polyacrylic acid treatment, metal soap treatment, amino acid treatment, inorganic compound treatment, plasma treatment, mechanochemical treatment, silane compound treatment, silazane compound treatment, etc. Among these treatments, treatment with silicone or silicone resin, treatment with silane compound or silazane compound, and metal soap treatment such as aluminum stearate, aluminum isostearate, or aluminum laurate are preferred from the viewpoint of dispersion stability, etc.

[0016] Examples of silicones or silicone resins include methylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, methylhydrogenpolysiloxane-dimethylpolysiloxane copolymer, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, octamethyltrisiloxane, 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, etc. As the methylhydrogenpolysiloxane-dimethylpolysiloxane copolymer, one represented by the following formula (1) is preferred.

[0017]

[0018] [In formula (1), m and n are integers of 0 or more, and 1≦m+n≦60.]

[0019] The silane compound or silazane compound is preferably a silane compound or silazane compound having an alkyl group having 1 to 20 carbon atoms or a fluoroalkyl group having 1 to 20 carbon atoms and reactive with inorganic oxides, and more preferably a silane compound represented by the following formula (2) or a silazane compound represented by the following formula (3). These compounds may be used alone or in combination of two or more.

[0020] R 4 (R 5 ) p Si(Z) 3-p ... (2)

[0021] [In formula (2), R 4 represents a linear or branched alkyl group having 1 to 20 carbon atoms or a linear or branched fluoroalkyl group having 1 to 20 carbon atoms; R 5represents a linear or branched alkyl group having 1 to 6 carbon atoms, Z represents a halogen atom or an alkoxy group, and p represents 0 or 1.

[0022] R 6 R 7 R 8 SiNHSiR 9 R 10 R 11 ...(3)

[0023] [In formula (3), R 6 ~R 11 each independently represents a linear or branched alkyl group having 1 to 20 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 20 carbon atoms.

[0024] As the silane compound, from the viewpoint of dispersion stability etc., alkylalkoxysilane or fluoroalkylalkoxysilane is preferred, and alkyltrialkoxysilane or fluoroalkyltrialkoxysilane is more preferred.Specific examples include hexyltrimethoxysilane, octyltrimethoxysilane, octyltriethoxysilane (triethoxycaprylylsilane), decyltrimethoxysilane, octadecyltrimethoxysilane, trifluoropropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane etc.It should be noted that one of these may be used alone or two or more may be used in combination.In addition, specific examples of the silazane compound include hexamethyldisilazane etc.

[0025] The coating amount of the surface treatment agent used in the hydrophobization treatment is preferably 3 parts by mass or more, more preferably 9 parts by mass or more, relative to 100 parts by mass of the fine particle metal oxide, from the viewpoints of emulsion stability, dispersion stability, etc., and is preferably 27 parts by mass or less, more preferably 22 parts by mass or less, relative to 100 parts by mass of the fine particle metal oxide, from the viewpoints of emulsion stability, dispersion stability, etc.

[0026] The hydrophobic treatment can be carried out by appropriately selecting a conventionally known method. For example, treatment with silicone or silicone resin includes, as described in Japanese Patent No. 3187440, a method in which a fine particle metal oxide is coated in a non-gas phase using at least one silicone compound (excluding silane compounds) composed of organopolysiloxanes and silicone resins, and then baked in an oxygen-containing atmosphere at a temperature of 600 to 950°C to coat the surface of the fine particle metal oxide with silicon oxide. Treatment methods using silane compounds or silazane compounds include chemical bonding methods, more specifically, a method in which a silane compound or silazane compound is mixed with a fine particle metal oxide in an organic solvent such as n-hexane, cyclohexane, or a lower alcohol, and then finely pulverized as necessary, and the organic solvent is then removed by heating (e.g., 80 to 250°C) or by reducing pressure. Another example is a method in which a surface is treated with a polysiloxane compound in water using a silane compound, as described in Japanese Patent Laid-Open No. 2007-326902.

[0027] The hydrophobic treated ultraviolet scattering agents may be used alone or in combination of two or more.

[0028] The content of the hydrophobized UV scattering agent in the core-shell particles is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2.5% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 18% by mass or more, based on the total mass of the core-shell particles, from the viewpoint of UV protection effect, etc., and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on the total mass of the core-shell particles, from the viewpoint of dispersion stability, etc. Specifically, the content is preferably 0.1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less, even more preferably 2.5% by mass or more and 25% by mass or less, even more preferably 5% by mass or more and 25% by mass or less, even more preferably 10% by mass or more and 25% by mass or less, even more preferably 18% by mass or more and 25% by mass or less, based on the total mass of the core-shell particles. By increasing the content of the hydrophobic treated UV scattering agent in the core-shell particles in this way, it is possible to further improve the UV protection effect while maintaining the absence of white cast, moisturizing feeling, and moisturizing properties. Furthermore, even when the content of the hydrophobic treated UV scattering agent in the core-shell particles is within this range, white cast is unlikely to occur after application to the skin.

[0029] The content of the hydrophobized UV scattering agent in the core-shell particles is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.5% by mass or more, and even more preferably 2.5% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, moisturizing feeling, moisturizing properties, irritation resistance, etc., and is preferably 24% by mass or less, more preferably 18% by mass or less, even more preferably 12% by mass or less, and even more preferably 5% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of absence of white cast, storage stability, etc. Specific ranges are preferably 0.1% by mass or more and 24% by mass or less, more preferably 0.5% by mass or more and 18% by mass or less, more preferably 1.5% by mass or more and 12% by mass or less, and even more preferably 2.5% by mass or more and 5% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention. When the content of the hydrophobized UV scattering agent in the core-shell particles is 1.5% by mass or more or 2.5% by mass or more, the UV protection effect, moisturizing feeling, moisturizing properties, irritation resistance, and storage stability are further improved, and when the content is 5% by mass or less, the absence of white foliage is further improved.

[0030] Furthermore, the content mass ratio of the hydrophobized UV scattering agent in the core-shell particles of component (a1) to the total of all hydrophobized UV scattering agents in the oil-in-water emulsion composition of the present invention [(a1) / (total hydrophobized UV scattering agent)] is preferably 0.05 or more and 1 or less, more preferably 0.1 or more and 0.9 or less, even more preferably 0.1 or more and 0.8 or less, and even more preferably 0.2 or more and 0.29 or less, from the viewpoints of UV protection effect, absence of white cast, moisturizing feel, moisturizing properties, irritation resistance, storage stability, etc. When the content mass ratio [(a1) / (total hydrophobized UV scattering agent)] is 0.1 or more or 0.2 or more, the UV protection effect, moisturizing feel, moisturizing properties, irritation resistance, and storage stability are particularly improved. Furthermore, when it is 0.29 or less, the UV protection effect and absence of white cast are further improved. The "total of all hydrophobized UV scattering agents in the oil-in-water emulsion composition" means the total of the hydrophobized UV scattering agents in the core-shell particles and the hydrophobized UV scattering agents outside the core-shell particles.

[0031] (a2) Oil Agent Liquid at 25°C) By incorporating an oil agent liquid at 25°C together with a hydrophobized UV scattering agent into the core portion of the core-shell particle, the hydrophobized UV scattering agent is dispersed in the oil agent liquid at 25°C, improving the UV protection effect when applied to the skin and reducing the likelihood of white cast. In this specification, the term "oil agent liquid at 25°C" refers to any oil agent that is liquid at 25°C under 1 atmosphere. It is broadly divided into oil-soluble UV absorbers that are liquid at 25°C under 1 atmosphere and other oil agents, with those that are not oil-soluble UV absorbers being preferred. The term "oil agent liquid at 25°C" excludes powder dispersants. The liquid oil agent may be either a volatile or non-volatile oil agent, but non-volatile oil agents are preferred from the viewpoints of the absence of white cast, moisturizing feel, moisturizing properties, irritation resistance, UV protection effect, etc. One type of oil agent may be used alone, or two or more types may be used in combination. A volatile oil is an oil that is volatile at 25°C, and a non-volatile oil is an oil that is not volatile at 25°C.

[0032] Examples of volatile oils include light isoparaffin, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, methyltrimethicone, decamethyltetrasiloxane, ethyltrisiloxane, and volatile methylpolysiloxane. Commercially available light isoparaffin products include Isopar H (manufactured by Esso Chemical Co., Ltd.), Isododecane (manufactured by Bayer), Isohexadecane (manufactured by Uniqema), IP Solvent 1620MU, IP Solvent 2028MU, and IP Solvent 2835 (all manufactured by Idemitsu Kosan Co., Ltd.). Commercially available decamethylcyclopentasiloxane products include TSF405 (manufactured by Momentive Performance Materials Japan, LLC), SH245, DC345 (manufactured by Dow Corning Toray Co., Ltd.), and KF-995 (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available methyl trimethicone products include Silicone TMF-1.5 (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available decamethyltetrasiloxane products include KF-96L-1.5CS (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available ethyltrisiloxane products include SILSOFTETS (manufactured by Momentive Performance Materials Japan LLC). Commercially available volatile methylpolysiloxane products include KF-96L-2CS (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0033] Examples of non-volatile oils include non-volatile hydrocarbon oils such as liquid paraffin (light liquid paraffin, light liquid isoparaffin, heavy liquid isoparaffin, etc.) and squalane; non-volatile silicone oils such as non-volatile dimethylpolysiloxane and non-volatile methylphenylpolysiloxane; non-volatile fatty acid ester oils such as cetyl 2-ethylhexanoate, isononyl isononanoate, isotridecyl isononanoate, isopropyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, and stearyl stearate; and C12-15 alkyl benzoates. Examples of non-volatile fatty acid ester oils that may be used include fatty acid triglycerides such as glyceryl tri(caprylate / caprate) and glyceryl tri(2-ethylhexanoate); esters of fatty acids and neopentyl glycol such as neopentyl glycol dicaprate and neopentyl glycol diethylhexanoate; and polyhydric alcohol fatty acid ester oils. Commercially available liquid paraffin products include Parleam 4 (manufactured by NOF Corporation). Commercially available non-volatile dimethylpolysiloxane products include KF-96A-10CS (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available isopropyl palmitate products include Exepar IPP (manufactured by Kao Corporation). Commercially available alkyl benzoate (C12-15) products include FINSOLV TN (manufactured by Innospec Active Chemicals). Commercially available neopentyl glycol dicaprate products include Estemol N-01 (manufactured by Nisshin Oillio Group, Ltd.).

[0034] The content of the oil agent that is liquid at 25°C in the core-shell particles is preferably 40% by mass or more, more preferably 50% by mass or more, based on the total mass of the core-shell particles, from the viewpoints of dispersion stability, ultraviolet protection effect, etc., and is preferably 80% by mass or less, more preferably 75% by mass or less, based on the total mass of the core-shell particles, from the viewpoints of ultraviolet protection effect, storage stability, etc. A specific range is preferably 40% by mass or more and 80% by mass or less, more preferably 50% by mass or more and 75% by mass or less, based on the total mass of the core-shell particles.

[0035] The content of the oil agent that is liquid at 25°C in the core-shell particles is preferably 0.5% by mass or more, more preferably 1% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of dispersion stability, UV protection effect, etc., and is preferably 25% by mass or less, more preferably 20% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, storage stability, etc. A specific range is preferably 0.5% by mass or more and 25% by mass or less, more preferably 1% by mass or more and 20% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0036] The mass ratio of component (a1) to component (a2) [(a1) / (a2)] is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more, from the viewpoints of the absence of white cast, UV protection effect, etc., and is preferably 2 or less, more preferably 1 or less, and even more preferably 0.5 or less, from the viewpoints of dispersion stability, UV protection effect, etc. Specifically, the range is preferably 0.01 or more and 2 or less, more preferably 0.05 or more and 1 or less, and even more preferably 0.1 or more and 0.5 or less.

[0037] ((a3) Powder Dispersant) From the viewpoints of UV protection effect, absence of white cast, dispersion stability, etc., the core portion of the core-shell particles preferably further contains (a3) ​​a powder dispersant in addition to components (a1) and (a2). The powder dispersant may be any that facilitates dispersion of the hydrophobized UV scattering agent in a liquid oil at 25°C. Examples include polyether-modified silicones; polyhydroxy fatty acids such as polyhydroxystearic acid; dipentaerythrityl tri-polyhydroxy fatty acids such as dipentaerythrityl tri-polyhydroxystearate; diglycerin difatty acid esters such as polyglyceryl diisostearate, polyglyceryl dilaurate, polyglyceryl distearate, and polyglyceryl dioleate. Of these, polyhydroxystearic acid is preferred as the powder dispersant to be contained in the core-shell particles.

[0038] The powder dispersants may be used alone or in combination of two or more.

[0039] The content of the powder dispersant in the core-shell particles is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and even more preferably 0.3% by mass or more, based on the total mass of the core-shell particles, from the viewpoints of the absence of whitish cast, dispersion stability, UV protection effect, etc., and is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1.5% by mass or less, and even more preferably 1% by mass or less, based on the total mass of the core-shell particles, from the viewpoints of dispersion stability, emulsion stability, etc. A specific range is preferably 0.03% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 3% by mass or less, more preferably 0.1% by mass or more and 1.5% by mass or less, even more preferably 0.3% by mass or more and 1% by mass or less, based on the total mass of the core-shell particles.

[0040] The content of the powder dispersant in the core-shell particles is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of the absence of white cast, dispersion stability, UV protection effect, etc., and is preferably 1% by mass or less, more preferably 0.3% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of dispersion stability, emulsion stability, etc. A specific range is preferably 0.005% by mass or more and 1% by mass or less, and more preferably 0.01% by mass or more and 0.3% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0041] The mass ratio of component (a3) ​​to component (a1) [(a3) / (a1)] is preferably 0.005 or more, more preferably 0.0075 or more, and even more preferably 0.01 or more, from the viewpoints of the absence of white cast, the absence of white cast, dispersion stability, UV protection effect, etc., and is preferably 0.15 or less, more preferably 0.1 or less, and even more preferably 0.05 or less, from the viewpoints of dispersion stability, emulsion stability, etc. A specific range is preferably 0.005 or more and 0.15 or less, more preferably 0.0075 or more and 0.1 or less, and even more preferably 0.01 or more and 0.05 or less.

[0042] The core-shell particles used in the present invention have a shell portion containing (b1) an anionic surfactant and (b2) a hydrophobic amphiphilic substance. By using such a shell portion encapsulating a core portion containing a hydrophobically treated UV scattering agent, the particles exert excellent UV protection effects and excellent moisturizing properties when applied to the skin, providing a moisturizing feeling and reducing the occurrence of whitish cast. Furthermore, when applied to the skin as an oil-in-water emulsion composition, irritation caused by friction of the applied surface with a mask or the like is reduced, and the particles are easily washed off during cleansing.

[0043] ((b1) Anionic Surfactant) Examples of anionic surfactants include fatty acid salts (preferably fatty acid salts having 12 to 24 carbon atoms) such as sodium laurate, potassium palmitate, and arginine stearate; alkyl sulfate salts (preferably alkyl sulfate salts having 12 to 24 carbon atoms) such as sodium lauryl sulfate, potassium lauryl sulfate, and sodium cetyl sulfate; polyoxyethylene alkyl ether sulfate salts (preferably polyoxyethylene alkyl ether sulfate salts having 12 to 24 carbon atoms) such as polyoxyethylene lauryl ether triethanolamine sulfate; N-acyl sarcosine salts (preferably N-acyl sarcosine salts having an acyl group having 12 to 24 carbon atoms) such as sodium lauroyl sarcosine; alkyl phosphates (preferably alkyl phosphates having 12 to 24 carbon atoms) such as sodium monostearyl phosphate; and polyoxyethylene alkyl ether salts (preferably polyoxyethylene oleyl ether sodium phosphate, polyoxyethylene stearyl ether sodium phosphate). Alkyl ether phosphates (preferably polyoxyethylene alkyl ether phosphates having 12 to 24 carbon atoms); dialkyl sulfosuccinates (preferably di(alkyl)sulfosuccinates having 6 to 12 carbon atoms) such as sodium di(2-ethylhexyl)sulfosuccinate; N-alkyloylmethyl taurine salts (preferably N-alkyl methyl taurine salts having an alkyloyl group having 12 to 24 carbon atoms) such as sodium N-stearoyl-N-methyl taurine and sodium N-myristoyl-N-methyl taurine; N-acyl glutamates (preferably N-acyl glutamates having an acyl group having 12 to 24 carbon atoms) such as monosodium N-lauroyl-L-glutamate, sodium N-myristoyl-L-glutamate, sodium N-stearoyl-L-glutamate, disodium N-stearoyl-L-glutamate, potassium N-stearoyl-L-glutamate, and arginine N-stearoyl-L-glutamate.

[0044] Among these anionic surfactants, N-acyl glutamates having an acyl group with 12 to 24 carbon atoms, N-alkyloylmethyl taurines having an alkyloyl group with 12 to 24 carbon atoms, fatty acid salts having 12 to 24 carbon atoms, and polyoxyethylene alkyl ether phosphates having 12 to 24 carbon atoms are preferred, and N-acyl glutamates having an acyl group with 12 to 24 carbon atoms and N-alkyloylmethyl taurines having an alkyloyl group with 12 to 24 carbon atoms are more preferred.

[0045] The anionic surfactants may be used alone or in combination of two or more.

[0046] The content of the anionic surfactant in the core-shell particles is preferably 0.5% by mass or more, more preferably 1% by mass or more, based on the total mass of the core-shell particles from the viewpoints of moisturizing feeling, moisturizing properties, storage stability, etc., and is preferably 15% by mass or less, more preferably 10% by mass or less, based on the total mass of the core-shell particles from the viewpoint of storage stability, etc. A specific range is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less, based on the total mass of the core-shell particles.

[0047] The content of the anionic surfactant in the core-shell particles is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of moisturizing feeling, moisturizing properties, storage stability, etc., and is preferably 3% by mass or less, more preferably 1.5% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoint of storage stability, etc. A specific range is preferably 0.05% by mass or more and 3% by mass or less, more preferably 0.1% by mass or more and 1.5% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention.

[0048] The mass ratio of component (b1) to component (a1) [(b1) / (a1)] is preferably 0.05 or more, more preferably 0.075 or more, and even more preferably 0.1 or more, from the viewpoint of storage stability, etc., and is preferably 1.5 or less, more preferably 1 or less, and even more preferably 0.5 or less, from the viewpoint of storage stability, etc. A specific range is preferably 0.05 or more and 1.5 or less, more preferably 0.075 or more and 1 or less, and even more preferably 0.1 or more and 0.5 or less.

[0049] (b2) Hydrophobic Amphiphilic Substances) Examples of hydrophobic amphiphilic substances include higher alcohols, ceramides, linear saturated fatty acids having 10 to 24 carbon atoms, polyhydric alcohol mono-C10 to 24 fatty acid esters, sorbitan di-C10 to 24 fatty acid esters, and polyhydric alcohol mono-C10 to 24 alkyl ethers.

[0050] As the higher alcohol, a monohydric alcohol having 10 to 24 carbon atoms is preferred, a monohydric alcohol having 12 to 22 carbon atoms is more preferred, and a monohydric alcohol having 14 to 22 carbon atoms is even more preferred. Furthermore, the higher alcohol may be linear or branched, and may be a saturated or unsaturated alcohol, with linear saturated or unsaturated alcohols being preferred. Examples of higher alcohols include lauryl alcohol, myristyl alcohol, cetanol, stearyl alcohol, behenyl alcohol, and oleyl alcohol. Of these, cetanol, stearyl alcohol, and behenyl alcohol are preferred, with cetanol being more preferred. The higher alcohols may be used alone or in combination of two or more.

[0051] The ceramides include one or more selected from natural ceramides and pseudo-ceramides. Preferred ceramides are those described in JP-A-2013-53146.

[0052] Specific examples of natural ceramides include ceramide Types 1 to 7, in which sphingosine, dihydrosphingosine, phytosphingosine, or sphingadienine is amidated (e.g., porcine and human ceramides shown in Figure 2 of J. Lipid Res., 24:759 (1983) and Figure 4 of J. Lipid. Res., 35:2069 (1994)). Furthermore, N-alkylated forms (e.g., N-methylated forms) of these ceramides are also included in natural ceramides. These ceramides may be optically active natural forms (D(-) forms), optically active non-natural forms (L(+) forms), or mixtures of natural and non-natural forms. The relative configuration of the compounds may be that of the natural form, other non-natural form, or a mixture thereof. Among natural ceramides, the compounds CERAMIDE 1, CERAMIDE 2, CERAMIDE 3, CERAMIDE 5, and CERAMIDE 6II (all INCI, 8th Edition) and those represented by the following formula are preferred.

[0053]

[0054] These may be either natural extracts or synthetic products, and commercially available products can be used. Examples of commercially available natural ceramides include Ceramide I, Ceramide III, Ceramide IIIA, Ceramide IIIB, Ceramide IIIC, and Ceramide VI (all manufactured by Cosmopharm Co., Ltd.), Ceramide TIC-001 (manufactured by Takasago International Corporation), CERAMIDE II (manufactured by Quest International), DS-Ceramide VI, DS-CLA-Phytoceramide, C6-Phytoceramide, DS-ceramide Y3S (manufactured by DOOSAN Co., Ltd.), and CERAMIDE 2 (manufactured by Sederma Co., Ltd.).

[0055]

[0056] The pseudo-ceramide is preferably a pseudo-ceramide represented by the following general formula:

[0057]

[0058] [In the formula, R 1 represents a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 10 to 22 carbon atoms which may be substituted with a hydroxyl group, or a hydrogen atom; X 1 represents a hydrogen atom, an acetyl group, or a glyceryl group; R 2 represents a linear, branched or cyclic saturated or unsaturated hydrocarbon group (the hydrocarbon group is preferably an alkyl group) having 5 to 22 carbon atoms which may be substituted with a hydroxyl group or an amino group, or a linear or branched, saturated or unsaturated fatty acid having 8 to 22 carbon atoms which may be substituted with a hydroxyl group which is ester-bonded to the ω-terminal of the hydrocarbon group (the hydrocarbon group is preferably an alkyl group); R 3 represents a hydrogen atom or a hydrocarbon group having a total of 1 to 30 carbon atoms (the hydrocarbon group is preferably an alkyl group) which may be substituted with a hydroxyl group, a hydroxyalkoxy group, an alkoxy group, or an acetoxy group.

[0059] Among pseudo-ceramides, those represented by the following formula are preferred, with N-(hexadecyloxyhydroxypropyl)-N-hydroxyethylhexadecanamide being more preferred.

[0060]

[0061]

[0062] As the linear saturated fatty acid having 10 to 24 carbon atoms, a linear saturated fatty acid having 12 to 24 carbon atoms is preferred, a linear saturated fatty acid having 14 to 22 carbon atoms is more preferred, and a linear saturated fatty acid having 16 to 18 carbon atoms is even more preferred. Examples thereof include lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid.

[0063] Examples of polyhydric alcohol mono-C10-24 fatty acid esters include glycerin mono-C10-24 fatty acid esters and sorbitan mono-C10-24 fatty acid esters. The fatty acid residue of the polyhydric alcohol mono-C10-24 fatty acid ester is preferably a fatty acid residue having 12 to 24 carbon atoms, more preferably a fatty acid residue having 14 to 24 carbon atoms, and even more preferably a fatty acid residue having 16 to 22 carbon atoms. The fatty acid residue may be a saturated fatty acid residue or an unsaturated fatty acid residue, and may be a straight-chain fatty acid residue or a branched fatty acid residue. Examples of glycerin mono-C10-24 fatty acid esters include glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, glycerin monooleate, and glycerin monoisostearate. Examples of sorbitan mono C10-24 fatty acid esters include sorbitan monolaurate, sorbitan monomyristate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monobehenate.

[0064] The fatty acid residue of the sorbitan di-C10-24 fatty acid ester is preferably a fatty acid residue having 12 to 24 carbon atoms, more preferably a fatty acid residue having 14 to 24 carbon atoms, and even more preferably a fatty acid residue having 16 to 22 carbon atoms. The fatty acid residue may be a saturated fatty acid residue or an unsaturated fatty acid residue, and may be a straight-chain fatty acid residue or a branched fatty acid residue. Examples of sorbitan di-C10-24 fatty acid ester include sorbitan dilaurate, sorbitan dimyristate, sorbitan dipalmitate, sorbitan distearate, and sorbitan dibehenate.

[0065] The polyhydric alcohol mono-C10-24 alkyl ether is preferably mono-C10-24 alkyl glyceryl ether, more preferably mono-C12-22 alkyl glyceryl ether, and even more preferably mono-C14-22 alkyl glyceryl ether. Examples of mono-C10-24 alkyl glyceryl ethers include monolauryl glyceryl ether, monomyristyl glyceryl ether, monocetyl glyceryl ether, monostearyl glyceryl ether, and monobehenyl glyceryl ether.

[0066] The hydrophobic amphiphilic substance may be used alone or in combination of two or more.

[0067] The content of the hydrophobic amphiphilic substance of component (b2) in the core-shell particles is preferably 1% by mass or more, more preferably 5% by mass or more, based on the total mass of the core-shell particles, from the viewpoints of moisturizing feeling, moisturizing properties, storage stability, etc., and is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total mass of the core-shell particles, from the viewpoint of storage stability, etc. A specific range is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 10% by mass or less, based on the total mass of the core-shell particles.

[0068] The content of the hydrophobic amphiphilic substance of component (b2) in the core-shell particles is preferably 0.025% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.075% by mass or more, and even more preferably 0.1% by mass or more, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of moisturizing feeling, moisturizing properties, storage stability, etc., and is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoint of storage stability, etc. Specific ranges are preferably 0.025% by mass or more and 10% by mass or less, more preferably 0.05% by mass or more and 8% by mass or less, more preferably 0.075% by mass or more and 5% by mass or less, and even more preferably 0.1% by mass or more and 2% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention.

[0069] The mass ratio of component (b2) to component (a1) [(b2) / (a1)] is preferably 0.05 or more, more preferably 0.075 or more, and even more preferably 0.1 or more, from the viewpoint of storage stability, etc., and is preferably 1.5 or less, more preferably 1 or less, and even more preferably 0.75 or less, from the viewpoint of storage stability, etc. Specifically, the range is preferably 0.05 or more and 1.5 or less, more preferably 0.075 or more and 1 or less, and even more preferably 0.1 or more and 0.75 or less.

[0070] Thus, the core-shell particles used in the present invention have a shell portion comprising (b1) an anionic surfactant and (b2) a hydrophobic amphiphilic substance. Therefore, the core-shell particles of the present invention may have an α-gel structure. When the core-shell particles have an α-gel structure, when applied to the skin, a coating film containing the core-shell particles is likely to be uniform and of appropriate thickness, further improving the UV protection effect, moisturizing properties, moisturizing feeling, and lack of white cast. Furthermore, after application to the skin, irritation when the applied surface is rubbed with a mask or the like is further reduced, and the particles are easier to wash off during cleansing. The α-gel structure can be confirmed by X-ray diffraction (XRD). Specifically, particles that exhibit at least one sharp diffraction peak near a Bragg angle of 21 to 22° in wide-angle X-ray diffraction can be determined to have an α-gel structure.

[0071] From the viewpoints of the absence of white cast, storage stability, UV protection effect, moisturizing property, moisturizing feeling, and irritation resistance, the core-shell particles preferably contain, in addition to components (a1) to (a2) and (b1) to (b2) (preferably components (a1) to (a3) ​​and (b1) to (b2)), one or more selected from (b3) an oil-based thickener and (b4) water; more preferably, in addition to components (a1) to (a2) and (b1) to (b2) (preferably components (a1) to (a3) ​​and (b1) to (b2)), further containing at least component (b3); and even more preferably, in addition to components (a1) to (a2) and (b1) to (b2) (preferably components (a1) to (a3) ​​and (b1) to (b2)), further containing components (b3) to (b4). The (b3) oil-based thickener is preferably contained in the core portion. (b4) It is preferable that water is contained at least in the shell portion.

[0072] (b3) Oil-based thickeners) Examples of oil-based thickeners include sugar fatty acid ester-based oil-based thickeners such as inulin fatty acid esters and dextrin fatty acid esters, as well as polyglyceryl isostearate, glyceryl (behenate / eicosanedioate), and organically modified clay minerals. These may be used alone or in combination of two or more. Of these, sugar fatty acid ester-based oil-based thickeners are preferred from the viewpoints of UV protection effect, dispersion stability, and the like. As the fatty acid residue in the sugar fatty acid ester-based oil-based thickener, a linear or branched saturated fatty acid residue is preferred. Furthermore, the number of carbon atoms in the fatty acid residue is preferably 8 to 24, more preferably 12 to 22, and even more preferably 14 to 20. As the sugar fatty acid ester-based oil-based thickener, dextrin fatty acid ester is preferred. Specific examples include dextrin myristate, dextrin palmitate, dextrin stearate, dextrin (palmitate / 2-ethylhexanoate), dextrin (palmitate / hexyldecanoate), and the like.

[0073] The oil-based thickeners may be used alone or in combination of two or more.

[0074] The content of the oil-based thickener in the core-shell particles is preferably 0.075% by mass or more, more preferably 0.1% by mass or more, based on the total mass of the core-shell particles, from the viewpoint of the dispersion stability of component (a1), etc., and is preferably 3% by mass or less, more preferably 1% by mass or less, based on the total mass of the core-shell particles, from the viewpoint of storage stability, etc. A specific range is preferably 0.075% by mass or more and 3% by mass or less, more preferably 0.1% by mass or more and 1% by mass or less, based on the total mass of the core-shell particles.

[0075] The content of the oil-based thickener in the core-shell particles is preferably 0.0075% by mass or more, more preferably 0.01% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of storage stability, moisturizing feeling, moisturizing properties, irritation resistance, UV protection effect, etc., and is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of storage stability, UV protection effect, etc. A specific range is preferably 0.0075% by mass or more and 0.5% by mass or less, and more preferably 0.01% by mass or more and 0.1% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0076] The content mass ratio of component (b3) to component (a1) [(b3) / (a1)] is preferably 0.005 or more, more preferably 0.01 or more, from the viewpoints of storage stability, moisturizing feeling, moisturizing properties, irritation resistance, UV protection effect, etc., and is preferably 0.1 or less, more preferably 0.05 or less, from the viewpoints of storage stability, UV protection effect, etc. Specifically, the range is preferably 0.005 or more and 0.1 or less, more preferably 0.01 or more and 0.05 or less.

[0077] ((b4) Water) The water of component (b4) refers to the water in the core-shell particles. The content of water in the core-shell particles is preferably 0% by mass or more, more preferably 5% by mass or more, based on the total mass of the core-shell particles from the viewpoints of moisturizing feeling, moisturizing properties, anti-irritation effect, etc., and is preferably 50% by mass or less, more preferably 30% by mass or less, based on the total mass of the core-shell particles from the viewpoints of storage stability, etc. A specific range of water content is preferably 0% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less, based on the total mass of the core-shell particles. The mass ratio of component (b4) to component (a1) [(b4) / (a1)] is preferably 1 or more and 10 or less, based on the viewpoints of UV protection effect, storage stability, etc.

[0078] In addition to the above components, the core-shell particles of the present invention may contain surfactants (excluding anionic surfactants and hydrophobic amphiphilic substances), oils that are solid at 25°C (note that the term "oils that are solid at 25°C" refers to a concept that excludes hydrophobic amphiphilic substances, and examples thereof include waxes such as ceresin, paraffin wax, polyolefin wax, and microcrystalline wax), powders (excluding hydrophobically treated UV scattering agents), water-soluble polymers, thickeners, disinfectants, moisturizers, humectants, colorants, preservatives, texture improvers, fragrances, anti-inflammatory agents, whitening agents, antiperspirants, antioxidants, and pH adjusters. These may be used alone or in combination of two or more.

[0079] Examples of surfactants other than anionic surfactants and hydrophobic amphiphiles include cationic surfactants and amphoteric surfactants. The content of surfactants other than anionic surfactants and hydrophobic amphiphiles in the core-shell particles is preferably 0% by mass or more and 1% by mass or less, more preferably 0% by mass or more and 0.1% by mass or less, even more preferably 0% by mass or more and 0.01% by mass or less, and still more preferably 0% by mass, relative to the total mass of the core-shell particles.

[0080] The content of the oil agent other than the hydrophobic amphiphilic substance that is solid at 25°C in the core-shell particles is preferably 0% by mass or more and 1% by mass or less, more preferably 0% by mass or more and 0.1% by mass or less, even more preferably 0% by mass or more and 0.01% by mass or less, and still more preferably 0% by mass, relative to the total mass of the core-shell particles.

[0081] The content of the ultraviolet absorber in the core-shell particles is preferably 0% by mass or more and 1% by mass or less, more preferably 0% by mass or more and 0.1% by mass or less, even more preferably 0% by mass or more and 0.01% by mass or less, and even more preferably 0% by mass, relative to the total mass of the core-shell particles. The oil-in-water emulsion composition of the present invention has excellent ultraviolet protection effect even when the content of the ultraviolet absorber is within such a range.

[0082] The average particle size of the core-shell particles is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.075 μm or more, even more preferably 0.1 μm or more, and even more preferably 0.2 μm or more, from the viewpoints of UV protection effect, storage stability, etc., and is preferably 15 μm or less, more preferably 7.5 μm or less, even more preferably 5 μm or less, even more preferably 2.5 μm or less, and even more preferably 0.5 μm or less, from the viewpoints of usability upon application, etc. Specific ranges of the average particle size are preferably 0.01 μm or more and 15 μm or less, more preferably 0.05 μm or more and 7.5 μm or less, even more preferably 0.075 μm or more and 5 μm or less, even more preferably 0.1 μm or more and 2.5 μm or less, and even more preferably 0.2 μm or more and 0.5 μm or less. When the average particle size of the core-shell particles is within these ranges, irritation resistance, resistance to phase inversion, and storage stability are further improved. The average particle size of the core-shell particles means the median diameter (D50), specifically, a value measured at 25°C using a laser diffraction / scattering particle size distribution measuring device.

[0083] The content of the core-shell particles is preferably 3% by mass or more, more preferably 7.5% by mass or more, and even more preferably 12.5% ​​by mass or more, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, increasing the thickness of the coating film, etc.; and from the viewpoints of storage stability at high temperatures, etc., it is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 27.5% by mass or less, and even more preferably 20% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention. Specific ranges are preferably 3% by mass or more and 35% by mass or less, more preferably 7.5% by mass or more and 30% by mass or less, and even more preferably 12.5% ​​by mass or more and 27.5% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention. When the content of the core-shell particles is 7.5% by mass or more or 12.5% ​​by mass or more, the UV protection effect, moisturizing feeling, moisturizing properties, irritation resistance, and storage stability are particularly improved. Furthermore, when it is 20% by mass or less, the UV protection effect and the absence of white cast are further improved.

[0084] ((e1) Second Hydrophobized UV Scattering Agent) The oil-in-water emulsion composition of the present invention contains (e1) a second hydrophobized UV scattering agent outside the core-shell particles, and the (e1) second hydrophobized UV scattering agent is dispersed. The (e1) second hydrophobized UV scattering agent is dispersed in the oil phase of the oil-in-water emulsion composition. By including the second hydrophobized UV scattering agent, the UV protection effect is improved.

[0085] Examples of the second hydrophobized UV scattering agent include the same hydrophobized UV scattering agent that can be used as component (a1). As the hydrophobized UV scattering agent, like the hydrophobized UV scattering agent that can be used as component (a1), a hydrophobized metal oxide fine particle is preferred. As the metal oxide used for the hydrophobized metal oxide fine particle, from the viewpoint of easy availability, one or more metal oxides selected from zinc oxide, titanium oxide, cerium oxide, iron oxide and chromium oxide are preferred. Among these metal oxides, from the viewpoint of UV protection effect, one or more metal oxides selected from zinc oxide, titanium oxide and cerium oxide are preferred, one or more metal oxides selected from zinc oxide and titanium oxide are more preferred, and titanium oxide is even more preferred. When hydrophobized titanium oxide fine particle is used as the second hydrophobized UV scattering agent, the UV protection effect and storage stability are particularly improved.

[0086] The shape of the "fine particle metal oxide" is not particularly limited, and examples thereof include spherical, plate-like, rod-like, spindle-like, needle-like, and irregular shapes. The average particle size of the "fine particle metal oxide" is preferably 0.01 μm or more, more preferably 0.012 μm or more, and even more preferably 0.015 μm or more, and is preferably 1 μm or less, more preferably 0.8 μm or less, and even more preferably 0.5 μm or less. The specific range of the average particle size is preferably 0.01 μm or more and 1 μm or less, more preferably 0.012 μm or more and 0.8 μm or less, and even more preferably 0.015 μm or more and 0.5 μm or less. The average particle size of the fine particle metal oxide means the average particle size measured by a laser diffraction / scattering method.

[0087] The hydrophobization treatment of the fine particle metal oxide may be carried out using a known surface treatment agent for hydrophobization, and examples thereof include fluorine compound treatment, silicone treatment, silicone resin treatment, pendant treatment, silane coupling agent treatment, titanium coupling agent treatment, oil treatment, N-acylated lysine treatment, polyacrylic acid treatment, metal soap treatment, amino acid treatment, inorganic compound treatment, plasma treatment, mechanochemical treatment, silane compound treatment, silazane compound treatment, etc. Among these treatments, treatment with silicone or silicone resin, treatment with silane compound or silazane compound, and metal soap treatment such as aluminum stearate, aluminum isostearate, or aluminum laurate are preferred from the viewpoint of dispersion stability, etc.

[0088] The second hydrophobic treated ultraviolet scattering agent may be used alone or in combination of two or more.

[0089] The content of the second hydrophobized UV scattering agent of component (e1) is preferably 3% by mass or more, more preferably 5% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoint of UV protection effect, etc., and from the viewpoint of the absence of white cast, storage stability, etc., it is preferably 25% by mass or less, more preferably 22.5% by mass or less, even more preferably 20% by mass or less, even more preferably 18% by mass or less, and even more preferably 15% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention. As a specific range, it is preferably 3% by mass or more and 25% by mass or less, more preferably 5% by mass or more and 22.5% by mass or less, more preferably 5% by mass or more and 20% by mass or less, even more preferably 5% by mass or more and 18% by mass or less, even more preferably 5% by mass or more and 15% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0090] The content mass ratio of the (e1) second hydrophobic treatment UV scattering agent to the (d1) second oil agent that is liquid at 25°C [(e1) / (d1)] is preferably 0.075 or more, more preferably 0.1 or more, from the viewpoint of UV protection effect, etc., and is preferably 1 or less, more preferably 0.75 or less, from the viewpoint of no white cast, storage stability, etc. Specifically, the range is preferably 0.075 or more and 1 or less, and more preferably 0.1 or more and 0.75 or less.

[0091] ((c4) Aqueous Thickener) The oil-in-water emulsion composition of the present invention contains (c4) an aqueous thickener in addition to the core-shell particles. This improves the UV protection effect when applied to the skin, and also improves the moisturizing properties, moisturizing feeling, and irritation resistance.

[0092] Examples of aqueous thickeners include poly(meth)acrylamide, copolymers of hydroxyethyl (meth)acrylate and (meth)acryloyldimethyl taurine salt, copolymers of (meth)acrylate and (meth)acryloyldimethyl taurine salt, copolymers of (meth)acrylamide and (meth)acrylate, copolymers of (meth)acrylic acid, (meth)acrylic acid amide, (meth)acrylate and (meth)acryloyldimethyl taurine salt, and copolymers of (meth)acryloyldimethyl taurine salt and vinylpyrrolidone. Poly(meth)acrylamide-based aqueous thickeners include copolymers of hydroxyethyl (meth)acrylate and (meth)acryloyldimethyl taurine salt, and copolymers of vinylpyrrolidone. Examples of aqueous thickeners include xanthan gum, dextrin, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl chitin, chitosan, and other polysaccharide-based thickeners, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, carboxyvinyl polymers, acrylic acid / alkyl acrylate copolymers (e.g., (acrylic acid / alkyl acrylate (C10-30)) copolymers), and the like. Among these, those using at least a poly(meth)acrylamide-based aqueous thickener are preferred, and those using a combination of a poly(meth)acrylamide-based aqueous thickener and a polysaccharide-based aqueous thickener are more preferred. In particular, when a copolymer of hydroxyethyl (meth)acrylate and (meth)acryloyldimethyltaurate salt, such as (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer, is used, storage stability and the absence of white cast are improved.

[0093] Commercially available polyacrylamides include Sepigel 305 (a mixture of polyacrylamide, hydrogenated polyisobutene, laureth-7, and water). Commercially available copolymers of hydroxyethyl acrylate and acryloyldimethyltaurate include SEPINOV EMT 10 (a mixture of (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer, sorbitan isostearate, and polysorbate 60), SIMULGEL NS (a mixture of (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer, squalane, polysorbate 60, and water), SIMULGEL FL (a mixture of (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer, isohexadecane, polysorbate 60, and water), and SEPIPLUS S (a mixture of (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer, polyisobutene, PEG-7 trimethylolpropane coconut oil alkyl ether, and water). A commercially available copolymer of an acrylate and an acryloyldimethyltaurate salt is SIMULGEL EG (a mixture of (sodium acrylate / sodium acryloyldimethyltaurate) copolymer, isohexadecane, polysorbate 80, sorbitan oleate, and water). A commercially available copolymer of an acrylamide and an acrylate salt is SEPIPLUS 265 (a mixture of (acrylamide / ammonium acrylate) copolymer, polyisobutene, polysorbate 20, and water). A commercially available copolymer of acrylic acid, acrylic acid amide, an acrylate, and an acryloyldimethyltaurate salt is SEPIPLUS 400 (a mixture of polyacrylate-13, polyisobutene, polysorbate 20, and water). A commercially available copolymer of acryloyldimethyltaurate and vinylpyrrolidone is Aristoflex AVC ((ammonium acryloyldimethyltaurate / VP) copolymer).

[0094] Furthermore, acid-type aqueous thickeners such as polyacrylic acid, carboxyvinyl polymers, and (acrylic acid / C10-30 alkyl acrylate) copolymers may be used as water-soluble or water-dispersible salts using an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide as a neutralizing agent.

[0095] The aqueous thickeners may be used alone or in combination of two or more.

[0096]

[0047] From the viewpoints of UV protection effect, moisturizing feeling, moisturizing properties, irritation resistance, storage stability, etc., the content of the aqueous thickener is preferably 0% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, and even more preferably 0.85% by mass or more, relative to the total mass of the oil-in-water emulsion composition of the present invention; and from the viewpoints of UV protection effect, absence of white cast, ease of rinsing, storage stability, etc., the content of the aqueous thickener is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, even more preferably 1.5% by mass or less, and even more preferably 1% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention. Specifically, the content of the aqueous thickener is preferably 0% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 3% by mass or less, even more preferably 0.1% by mass or more and 2% by mass or less, even more preferably 0.5% by mass or more and 1.5% by mass or less, even more preferably 0.8% by mass or more and 1% by mass or less, and even more preferably 0.85% by mass or more and 1% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention. When the content of the aqueous thickener is 0.8% by mass or more or 0.85% by mass or more, the UV protection effect, moisturizing feeling, moisturizing properties, irritation resistance, and storage stability when applied to the skin are further improved. When the content is 1% by mass or less, the UV protection effect, lack of white cast, ease of rinsing, and storage stability when applied to the skin are further improved.

[0097] The mass ratio of the aqueous thickener (c4) to the core-shell particles [(c4) / (core-shell particles)] is preferably 0.005 or more, more preferably 0.0075 or more, and even more preferably 0.01 or more, from the viewpoints of UV protection effect, absence of white cast, moisturizing feel, moisturizing properties, resistance to irritation, etc., and is preferably 1 or less, more preferably 0.75 or less, and even more preferably 0.5 or less, from the viewpoints of UV protection effect, absence of white cast, etc. Specifically, the range is preferably 0.005 or more and 1 or less, more preferably 0.0075 or more and 0.75 or less, and even more preferably 0.01 or more and 0.5 or less.

[0098] The oil-in-water emulsion composition of the present invention contains, in addition to the core-shell particles, (e1) a second hydrophobized UV scattering agent, and (c4) an aqueous thickener, (c1) water and (d1) a second oil agent that is liquid at 25°C. However, from the viewpoints of UV protection effect, storage stability, moisturizing property, moisturizing feeling, irritation resistance, etc., it preferably further contains one or more selected from (c2) a volatile medium other than water, (c3) a polyhydric alcohol, (d2) a second surfactant, (d3) a second powder dispersant, and (d4) an amphiphilic solid fat; it is more preferred that the emulsion composition contains at least component (d2); it is even more preferred that the emulsion composition contains at least components (d2) and (d4); and it is even more preferred that the emulsion composition contains component (c3) and components (d2) to (d4).

[0099] ((c1) Water) The water of component (c1) refers to water outside the core-shell particles (water in the liquid phase). The content of water of component (c1) is preferably 5% by mass or more, more preferably 30% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of storage stability, absence of white cast, ease of rinsing, etc., and is preferably 60% by mass or less, more preferably 50% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoint of UV protection effect, etc. The specific range is preferably from 5% by mass to 60% by mass, and more preferably from 30% by mass to 50% by mass, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0100] ((d1) Second Oil Agent Liquid at 25°C) The second oil agent liquid at 25°C of component (d1) refers to an oil agent liquid at 25°C outside the core-shell particles. Examples of the second oil agent liquid at 25°C include the same oil agents liquid at 25°C as those usable as component (a2), and it is preferable that the second oil agent is not an oil-soluble UV absorber. The liquid oil agent may be either a volatile oil agent or a non-volatile oil agent, but a non-volatile oil agent is preferred from the viewpoints of UV protection effect, absence of white cast, moisturizing properties, moisturizing feel, irritation resistance, storage stability, etc. One type of oil agent may be used alone, or two or more types may be used in combination.

[0101] Examples of volatile oils include light isoparaffin, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, methyltrimethicone, decamethyltetrasiloxane, ethyltrisiloxane, and volatile methylpolysiloxane. Commercially available light isoparaffin products include Isopar H (manufactured by Esso Chemical Co., Ltd.), Isododecane (manufactured by Bayer), Isohexadecane (manufactured by Uniqema), IP Solvent 1620MU, IP Solvent 2028MU, and IP Solvent 2835 (all manufactured by Idemitsu Kosan Co., Ltd.). Commercially available decamethylcyclopentasiloxane products include TSF405 (manufactured by Momentive Performance Materials Japan, LLC), SH245, DC345 (manufactured by Dow Corning Toray Co., Ltd.), and KF-995 (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available methyl trimethicone products include Silicone TMF-1.5 (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available decamethyltetrasiloxane products include KF-96L-1.5CS (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available ethyltrisiloxane products include SILSOFTETS (manufactured by Momentive Performance Materials Japan LLC). Commercially available volatile methylpolysiloxane products include KF-96L-2CS (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0102] Examples of non-volatile oils include non-volatile hydrocarbon oils such as liquid paraffin (light liquid paraffin, light liquid isoparaffin, heavy liquid isoparaffin, etc.), hydrogenated polyisobutene, isohexadecane, and squalane; non-volatile silicone oils such as non-volatile dimethylpolysiloxane and non-volatile methylphenylpolysiloxane; non-volatile fatty acid ester oils such as cetyl 2-ethylhexanoate, isononyl isononanoate, isotridecyl isononanoate, isopropyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, and stearyl stearate; and alkyl benzoates (C12-15). In addition, examples of non-volatile fatty acid ester oils that may be used include fatty acid triglycerides such as glyceryl tri(caprylate / caprate) and glyceryl tri(2-ethylhexanoate); esters of fatty acids and neopentyl glycol such as neopentyl glycol dicaprate and neopentyl glycol diethylhexanoate; and polyhydric alcohol fatty acid ester oils. Commercially available liquid paraffin includes Parleam 4 (manufactured by NOF Corporation). Commercially available non-volatile dimethylpolysiloxane includes KF-96A-10CS (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available isopropyl palmitate includes Exepar IPP (manufactured by Kao Corporation). Commercially available alkyl benzoate (C12-15) includes FINSOLV TN (manufactured by Innospec Active Chemicals). Commercially available neopentyl glycol dicaprate products include Esthemol N-01 (manufactured by Nisshin Oillio Group, Ltd.).

[0103] The content of the second oil agent that is liquid at 25°C is preferably 7.5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, absence of white cast, moisturizing feel, moisturizing properties, irritation resistance, etc., and is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoint of storage stability, etc. A specific range is preferably from 7.5% by mass to 35% by mass, more preferably from 10% by mass to 30% by mass, and even more preferably from 15% by mass to 25% by mass, relative to the total mass of the oil-in-water emulsion composition of the present invention.

[0104] The mass ratio of the content of the second oil (d1) that is liquid at 25°C to the core-shell particles [(d1) / (core-shell particles)] is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.3 or more from the viewpoints of UV protection effect, absence of white cast, moisturizing feel, moisturizing properties, irritation resistance, etc., and is preferably 9 or less, more preferably 7 or less, and even more preferably 5 or less from the viewpoints of storage stability, etc. Specifically, the range is preferably 0.05 or more and 9 or less, more preferably 0.1 or more and 7 or less, and even more preferably 0.3 or more and 5 or less.

[0105] ((d2) Second Surfactant) The second surfactant of component (d2) refers to a surfactant outside the core-shell particles. When the oil-in-water emulsion composition of the present invention contains the second surfactant (d2), the UV protection effect, absence of white cast, moisturizing properties, moisturizing feel, irritation resistance, ease of cleansing, and storage stability are further improved. Examples of the second surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. These can be used alone or in combination of two or more. Of these, nonionic surfactants are preferred. When a nonionic surfactant is used as the second surfactant, the UV protection effect, absence of white cast, moisturizing properties, moisturizing feel, irritation resistance, ease of cleansing, and storage stability are further improved. Examples of nonionic surfactants include sorbitan fatty acid esters such as sorbitan monostearate and sorbitan monoisostearate; polyoxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate; polyoxyalkylene alkyl ethers such as polyoxyethylene (average number of moles of EO added: 7) lauryl ether; and polyoxyalkylene hydrogenated castor oils such as polyoxyethylene hydrogenated castor oil (average number of moles of EO added: 60) and polyoxyethylene hydrogenated castor oil (average number of moles of EO added: 40). Among these, polyoxyalkylene sorbitan fatty acid esters, sorbitan fatty acid esters, polyoxyalkylene alkyl ethers and polyoxyalkylene hydrogenated castor oil are preferred as the second surfactant.

[0106] The content of the second surfactant is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, moisture retention, moisturizing feeling, irritation resistance, ease of washing, etc. Furthermore, from the viewpoints of UV protection effect, absence of white cast, moisture retention, moisturizing feeling, irritation resistance, ease of washing, storage stability, etc., the content is preferably 5% by mass or less, more preferably 2.5% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention. A specific range is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, and even more preferably 1% by mass or more and 2.5% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention. When the content of the second surfactant in the oil-in-water emulsion composition is 1% by mass or more, the UV protection effect, moisture retention, moisturizing feeling, irritation resistance, and ease of washing are further improved. When the content is 2.5% by mass or less, the moisturizing property, moisturizing feeling, irritation resistance, ease of washing, and storage stability are further improved.

[0107] The mass ratio of the content of the second surfactant (d2) to the core-shell particle [(d2) / (core-shell particle)] is preferably 0.005 or more, more preferably 0.0075 or more, and even more preferably 0.01 or more, from the viewpoints of moisturizing feeling, moisturizing properties, irritation resistance, storage stability, etc., and is preferably 1 or less, more preferably 0.75 or less, and even more preferably 0.5 or less, from the viewpoint of storage stability, etc. Specifically, the range is preferably 0.005 or more and 1 or less, more preferably 0.0075 or more and 0.75 or less, and even more preferably 0.01 or more and 0.5 or less.

[0108] (c2) Volatile Medium Other Than Water Examples of the volatile medium other than water include lower alcohols such as ethanol and isopropanol. From the viewpoints of UV protection effect, moisturizing feeling, moisturizing properties, irritation resistance, storage stability, etc., the content of the volatile medium other than water is preferably 0% by mass or more and 1% by mass or less, more preferably 0% by mass or more and 0.1% by mass or less, even more preferably 0% by mass or more and 0.01% by mass or less, and even more preferably 0% by mass, relative to the total mass of the oil-in-water emulsion composition of the present invention.

[0109] ((c3) Polyhydric Alcohol) The polyhydric alcohol of component (c3) refers to a polyhydric alcohol outside the core-shell particles. Examples of polyhydric alcohols include glycols and glycerins. Examples of glycols include alkylene glycols such as ethylene glycol, propylene glycol, trimethylene glycol (1,3-propanediol), and 1,3-butylene glycol; dialkylene glycols such as diethylene glycol and dipropylene glycol; and polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Examples of glycerins include glycerin, diglycerin, and polyglycerin. Among these, glycols are preferred, and alkylene glycols are more preferred, from the viewpoints of storage stability, moisturizing properties, moisturizing feel, irritation resistance, and UV protection effect.

[0110] The polyhydric alcohols may be used alone or in combination of two or more.

[0111] The content of the polyhydric alcohol is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, moisturizing feeling, moisturizing properties, irritation resistance, etc., and is preferably 20% by mass or less, more preferably 17.5% by mass or less, and even more preferably 15% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoint of storage stability, etc. A specific range is preferably 1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 17.5% by mass or less, and even more preferably 3% by mass or more and 15% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0112] ((d3) Second Powder Dispersant) The second powder dispersant of component (d3) refers to a powder dispersant other than the core-shell particles. The second powder dispersant may be any that facilitates dispersion of the hydrophobized UV scattering agent in a liquid oil at 25°C. Examples include polyether-modified silicones; polyhydroxy fatty acids such as polyhydroxystearic acid; dipentaerythrityl tri-polyhydroxy fatty acids such as dipentaerythrityl tri-polyhydroxystearate; diglycerin difatty acid esters such as polyglyceryl diisostearate, polyglyceryl dilaurate, polyglyceryl distearate, and polyglyceryl dioleate; and sorbitan difatty acid esters such as sorbitan dilaurate, sorbitan dimyristate, sorbitan dipalmitate, sorbitan distearate, and sorbitan dibehenate. Among these, dipentaerythrityl tri-polyhydroxy fatty acids, diglycerin difatty acid esters, and sorbitan difatty acid esters are preferred from the viewpoint of dispersion stability, etc.

[0113] The second powder dispersant may be used alone or in combination of two or more.

[0114] The content of the second powder dispersant is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention from the viewpoints of UV protection effect, absence of white cast, etc., and is preferably 5% by mass or less, more preferably 1.5% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention from the viewpoints of storage stability, etc. A specific range is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.5% by mass or more and 1.5% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0115] The content mass ratio of the second powder dispersant (d3) to the second hydrophobic treated ultraviolet scattering agent (e1) [(d3) / (e1)] is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.075 or more from the viewpoints of ultraviolet protection effect, absence of white cast, etc., and is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.3 or less from the viewpoint of storage stability, etc. As a specific range, 0.01 or more and 1 or less are preferred, 0.05 or more and 0.5 or less are more preferred, and 0.075 or more and 0.3 or less are even more preferred.

[0116] ((d4) Amphiphilic Solid Fat) The amphiphilic solid fat of component (d4) refers to an amphiphilic solid fat outside the core-shell particles. Examples of amphiphilic solid fats include higher alcohols, ceramides, polyhydric alcohol mono-C10-24 fatty acid esters, and polyhydric alcohol mono-C10-24 alkyl ethers. Examples of higher alcohols, ceramides, polyhydric alcohol mono-C10-24 fatty acid esters, and polyhydric alcohol mono-C10-24 alkyl ethers include the same as those listed as (b2) hydrophobic amphiphilic substances. Among such amphiphilic solid fats, higher alcohols are preferred. As the higher alcohol, a monohydric alcohol having 10 to 24 carbon atoms is preferred, a monohydric alcohol having 12 to 22 carbon atoms is more preferred, and a monohydric alcohol having 14 to 22 carbon atoms is even more preferred. The higher alcohol may be linear or branched, and may be saturated or unsaturated, but a linear saturated or unsaturated alcohol is preferred. Examples of higher alcohols include lauryl alcohol, myristyl alcohol, cetanol, stearyl alcohol, behenyl alcohol, oleyl alcohol, etc. Among these, cetanol, stearyl alcohol, and behenyl alcohol are preferred, and cetanol is more preferred.

[0117] The amphiphilic solid fats may be used alone or in combination of two or more.

[0118] The content of the amphiphilic solid fat is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of storage stability, moisturizing feeling, moisturizing properties, irritation resistance, etc., and is preferably 1% by mass or less, more preferably 0.75% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, absence of white cast, etc. A specific range is preferably 0.05% by mass or more and 1% by mass or less, more preferably 0.1% by mass or more and 0.75% by mass or less, relative to the total mass of the oil-in-water emulsion composition of the present invention.

[0119] The mass ratio of the amphiphilic solid fat (d4) to the core-shell particles [(d4) / (core-shell particles)] is preferably 0.005 or more, more preferably 0.01 or more, from the viewpoints of storage stability, moisturizing feeling, moisturizing properties, irritation resistance, etc., and is preferably 0.6 or less, more preferably 0.2 or less, from the viewpoints of UV protection effect, absence of white cast, etc. Specifically, the range is preferably 0.005 or more and 0.6 or less, more preferably 0.01 or more and 0.2 or less.

[0120] In addition to the above-mentioned components, the oil-in-water emulsion composition of the present invention may contain basic substances, chelating agents, preservatives, moisturizing agents, pH adjusters, fragrances, cosmetic ingredients, medicinal ingredients, oil gelling agents, bactericides, antioxidants, etc. These may be used alone or in combination of two or more.

[0121] The total content of the liquid phase in the oil-in-water emulsion composition is preferably 55% by mass or more, more preferably 60% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, storage stability, moisturizing feeling, moisturizing ability, irritation resistance, etc.; and from the viewpoints of moisturizing feeling, moisturizing ability, irritation resistance, etc., it is preferably 95% by mass or less, more preferably 90% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention. A specific range is preferably 55% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention. Note that the "total content of the liquid phase" refers to the total mass of the oil-in-water emulsion composition excluding particle and powder components.

[0122] The content mass ratio of the core-shell particles to the liquid phase of the oil-in-water emulsion composition [(core-shell particles) / (liquid phase)] is preferably 0.01 or more, more preferably 0.1 or more, from the viewpoints of UV protection effect, moisturizing feeling, moisturizing property, irritation resistance, etc., and is preferably 0.5 or less, more preferably 0.3 or less, from the viewpoint of storage stability, etc. A specific range is preferably 0.01 or more and 0.5 or less, more preferably 0.1 or more and 0.3 or less.

[0123] The total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition is preferably 4% by mass or more, more preferably 8% by mass or more, and even more preferably 11% by mass or more, based on the total mass of the oil-in-water emulsion composition of the present invention, from the viewpoints of UV protection effect, storage stability, moisturizing property, moisturizing feeling, resistance to irritation, etc.; and from the viewpoints of absence of white cast, storage stability, etc., the total content is preferably 32.5% by mass or less, more preferably 30% by mass or less, even more preferably 27.5% by mass or less, even more preferably 25% by mass or less, even more preferably 22% by mass or less, even more preferably 20% by mass or less, and even more preferably 18% by mass or less, based on the total mass of the oil-in-water emulsion composition of the present invention. Specifically, the content of the hydrophobic treated UV scattering agent in the oil-in-water emulsion composition of the present invention is preferably 4% by mass or more and 32.5% by mass or less, more preferably 8% by mass or more and 30% by mass or less, even more preferably 11% by mass or more and 27.5% by mass or less, even more preferably 11% by mass or more and 25% by mass or less, even more preferably 11% by mass or more and 22% by mass or less, even more preferably 11% by mass or more and 20% by mass or less, and even more preferably 11% by mass or more and 18% by mass or less. Even when the total content of all hydrophobic treated UV scattering agents in the oil-in-water emulsion composition of the present invention is high, it is unlikely to cause a white cast after application to the skin. Furthermore, when the total content of all hydrophobic treated UV scattering agents in the oil-in-water emulsion composition is 11% by mass or more, the UV protection effect, moisturizing property, moisturizing feeling, irritation resistance, and storage stability are further improved.

[0124] The mass ratio of the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition to the total content of all oils that are liquid at 25°C in the oil-in-water emulsion composition (preferably the sum of components (a2) and (d1)) [(total hydrophobized UV scattering agents in the oil-in-water emulsion composition) / (total oils that are liquid at 25°C in the oil-in-water emulsion composition)] is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.4 or more from the viewpoint of UV protection effect, etc., and is preferably 1 or less, more preferably 0.75 or less, even more preferably 0.5 or less, and even more preferably 0.48 or less from the viewpoint of absence of white cast, storage stability, etc. Specific ranges are preferably 0.1 or more and 1 or less, more preferably 0.1 or more and 0.75 or less, more preferably 0.3 or more and 0.5 or less, even more preferably 0.4 or more and 0.48 or less. When the content mass ratio [(total hydrophobized UV scattering agents in the oil-in-water emulsion composition) / (total oil agents that are liquid at 25°C in the oil-in-water emulsion composition)] is set to 0.48 or less, the UV protection effect and storage stability are further improved.

[0125] The content mass ratio of the total water in the oil-in-water emulsion composition to the total hydrophobized UV scattering agents in the oil-in-water emulsion composition [(water in the oil-in-water emulsion composition) / (total hydrophobized UV scattering agents in the oil-in-water emulsion composition)] is preferably 1 or more, more preferably 1.4 or more, even more preferably 1.8 or more, from the viewpoint of storage stability, etc., and is preferably 5.5 or less, more preferably 4.5 or less, even more preferably 3.5 or less, from the viewpoint of UV protection effect, etc. Specific ranges are preferably 1 or more and 5.5 or less, more preferably 1.4 or more and 4.5 or less, and even more preferably 1.8 or more and 3.5 or less. When the content mass ratio [(water in the oil-in-water emulsion composition) / (total hydrophobized UV scattering agents in the oil-in-water emulsion composition)] is 4.5 or less or 3.5 or less, the UV protection effect and storage stability are further improved.

[0126] The mass ratio of the total amount of oils that are liquid at 25°C in the oil-in-water emulsion composition (preferably the total amount of components (a2) and (d1)) to the total amount of water in the oil-in-water emulsion composition [(all oils that are liquid at 25°C in the oil-in-water emulsion composition) / (water in the oil-in-water emulsion composition)] is preferably 0.3 or more and 2 or less, more preferably 0.5 or more and 1.5 or less, from the viewpoints of UV protection effect, absence of white cast, moisturizing feel, moisturizing properties, irritation resistance, etc. When the mass ratio [(all oils that are liquid at 25°C in the oil-in-water emulsion composition) / (water in the oil-in-water emulsion composition)] is 0.5 or more, the UV protection effect and storage stability are further improved.

[0127] Furthermore, the oil-in-water emulsion composition of the present invention can achieve a high UV protection effect even when the content of the UV absorber is reduced or no UV absorber is used. The total content of the UV absorbers is preferably 0% by mass or more and 20% by mass or less, more preferably 0% by mass or more and 5% by mass or less, even more preferably 0% by mass or more and 1% by mass or less, even more preferably 0% by mass or more and 0.1% by mass or less, even more preferably 0% by mass or more and 0.01% by mass or less, and even more preferably 0% by mass, based on the total mass of the oil-in-water emulsion composition of the present invention.

[0128] The viscosity of the oil-in-water emulsion composition of the present invention at 25°C is preferably 6,000 mPa·s or more, more preferably 15,000 mPa·s or more, from the viewpoint of resistance to dripping, etc., and is preferably 100,000 mPa·s or less, more preferably 50,000 mPa·s or less, from the viewpoint of UV protection effect, spreadability upon application, absence of white cast, etc. Specific ranges are preferably 6,000 mPa·s or more and 100,000 mPa·s or less, and more preferably 15,000 mPa·s or more and 50,000 mPa·s or less. The viscosity at 25°C can be measured using a TVB-10 viscometer under the measurement conditions of rotor No. 4, 6 rpm, and 1 min.

[0129] The pH of the oil-in-water emulsion composition of the present invention at 25° C. is preferably 7 or more and 8.5 or less from the viewpoint of storage stability and the like.

[0130] The oil-in-water emulsion composition of the present invention is an oil-in-water emulsion composition in a liquid phase. This provides a fresh and light feel when used and makes it easy to wash off during cleansing. Furthermore, the oil-in-water emulsion composition of the present invention is less likely to produce a white cast after application, even when the oil-in-water emulsion composition contains a high content of a hydrophobized UV scattering agent.

[0131] The oil-in-water emulsion composition of the present invention can be produced by appropriately combining the methods described in JP-A-2017-7969, JP-A-2020-63239, JP-A-2022-186915, JP-A-2022-117486, WO2023 / 286780, etc. For example, the core-shell particles can be produced by: (Step A1) preparing a slurry containing (a1) a hydrophobized UV scattering agent, (a2) an oil agent liquid at 25°C, and optionally (a3) ​​a powder dispersant; (b1) an anionic surfactant, (b2) a hydrophobic amphiphilic substance, and optionally (b3) an oil-based thickener, while heating and mixing; (Step A2) forming an oil-in-water emulsion by adding water dropwise to the composition obtained in Step A1 at 80 to 120°C while circulating the composition in a homogenizer; and (Step A3) cooling the oil-in-water emulsion obtained in Step A2 at a cooling rate of 0.5 to 5°C / second. Examples of cooling methods for Step A3 include continuous rapid cooling using a vibration-type agitation mixer, scraper-type heat exchanger, static mixer, plate-type heat exchanger, double-pipe heat exchanger, or the like, or by agitating and cooling in a general blending vessel.

[0132] Next, the obtained core-shell particles are mixed with (c1) water, (c4) an aqueous thickener, and, if necessary, (c2) a volatile medium other than water or (c3) a polyhydric alcohol, and an oil phase component obtained by mixing or dispersing (d1) a second oil agent that is liquid at 25°C, (d2) a surfactant, (e1) a second hydrophobized UV scattering agent, and, if necessary, other components, is added to the mixture, thereby producing the oil-in-water emulsion composition of the present invention.

[0133] Furthermore, when applied to skin, the oil-in-water emulsion composition of the present invention exhibits moisturizing properties and a moisturizing feel, exhibits excellent UV protection effects, is less likely to produce white cast, and can suppress irritation when the surface of the applied area is rubbed. While the reasons for these effects are not entirely clear, the present inventors speculate that the oil-in-water emulsion composition of the present invention is likely to be due to the fact that, even when applied to skin and the moisture evaporates, the core-shell particles are less likely to collapse and maintain their thickness, the core-shell particles and the hydrophobized UV scattering agent therein do not aggregate with each other and remain dispersed, and furthermore, the coating film containing the core-shell particles is more likely to maintain a uniform and appropriate thickness. The present inventors also speculate that one of the mechanisms for the moisturizing feel and moisturizing properties is the ease with which the core-shell particles retain moisture. Furthermore, since the hydrophobized UV scattering agent in the core-shell particles is more likely to be uniformly distributed, even when the content of the hydrophobized UV scattering agent in the core-shell particles is increased, the composition is more likely to exhibit excellent UV protection effects and is less likely to produce white cast.

[0134] Therefore, the oil-in-water emulsion composition of the present invention is useful as a cosmetic (for example, sunscreen, foundation, makeup base, lotion, emulsion, cream, gel, serum, sheet-type cosmetic), and is particularly useful as a sunscreen. The oil-in-water emulsion composition of the present invention is also useful for skin (preferably skin excluding the scalp, more preferably the face, body, hands, feet, etc.), and can be used as a sunscreen by applying it to the skin using a method appropriate for the type of formulation. The method of use is not particularly limited, but application by hand or with an applicator is preferred.

[0135] In relation to the above-described embodiments, the present invention further discloses the following oil-in-water emulsion compositions, etc.: <1> An oil-in-water emulsion composition comprising core-shell particles, the core of which contains the following components (a1) and (a2): (a1) a hydrophobized ultraviolet scattering agent, and (a2) an oil agent that is liquid at 25°C, and the shell of which contains the following components (b1) and (b2): (b1) an anionic surfactant, and (b2) a hydrophobic amphiphilic substance, (e1) a second hydrophobized ultraviolet scattering agent, and (c4) an aqueous thickener, in which the core-shell particles and (e1) the second hydrophobized ultraviolet scattering agent are dispersed.

[0136] <2> The oil-in-water emulsion composition according to <1>, wherein component (a1) is preferably a hydrophobized fine particle metal oxide, more preferably one or more fine particle metal oxides selected from zinc oxide, titanium oxide, cerium oxide, iron oxide, and chromium oxide that have been hydrophobized, even more preferably one or more fine particle metal oxides selected from zinc oxide, titanium oxide, and cerium oxide that have been hydrophobized, even more preferably one or more fine particle metal oxides selected from zinc oxide and titanium oxide that have been hydrophobized, and even more preferably hydrophobized fine particle titanium oxide. <3> The oil-in-water emulsion composition according to <1> or <2>, wherein the hydrophobization treatment of component (a1) is preferably a hydrophobization treatment selected from treatment with a fluorine compound, silicone treatment, silicone resin treatment, pendant treatment, treatment with a silane coupling agent, treatment with a titanium coupling agent, treatment with an oil, treatment with an N-acylated lysine, treatment with polyacrylic acid, treatment with a metal soap, treatment with an amino acid, treatment with an inorganic compound, plasma treatment, mechanochemical treatment, treatment with a silane compound, and treatment with a silazane compound, and more preferably a hydrophobization treatment selected from treatment with a silicone resin, treatment with a silane compound, treatment with a silazane compound, and treatment with a metal soap.

[0137] <4> The oil-in-water emulsion composition according to any one of <1> to <3>, wherein the content of component (a1) is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2.5% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 18% by mass or more, relative to the total mass of the core-shell particles, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, relative to the total mass of the core-shell particles. <5> The oil-in-water emulsion composition according to any one of <1> to <3>, wherein the content of component (a1) is preferably 0.1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less, even more preferably 2.5% by mass or more and 25% by mass or less, even more preferably 5% by mass or more and 25% by mass or less, even more preferably 10% by mass or more and 25% by mass or less, and even more preferably 18% by mass or more and 25% by mass or less, relative to the total mass of the core-shell particles.

[0138] <6> The oil-in-water emulsion composition according to any one of <1> to <5>, wherein the content of the hydrophobized UV scattering agent in the core-shell particles is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.5% by mass or more, and even more preferably 2.5% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 24% by mass or less, more preferably 18% by mass or less, even more preferably 12% by mass or less, and even more preferably 5% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <7> The oil-in-water emulsion composition according to any one of <1> to <6>, wherein the mass ratio of the content of the hydrophobized UV scattering agent in the core-shell particles of component (a1) to the sum of all hydrophobized UV scattering agents in the oil-in-water emulsion composition [(a1) / (total hydrophobized UV scattering agents)] is preferably 0.05 or more and 1 or less, more preferably 0.1 or more and 0.9 or less, even more preferably 0.1 or more and 0.8 or less, and even more preferably 0.2 or more and 0.29 or less.

[0139] <8> The oil-in-water emulsion composition according to any one of <1> to <7>, wherein the component (a2) is preferably a non-volatile oil, more preferably one or more non-volatile oils selected from the group consisting of non-volatile hydrocarbon oils, non-volatile silicone oils, non-volatile fatty acid ester oils, and C12-15 alkyl benzoates. <9> The oil-in-water emulsion composition according to any one of <1> to <8>, wherein the content of the oil that is liquid at 25°C in the core-shell particles is preferably 40% by mass or more, more preferably 50% by mass or more, relative to the total mass of the core-shell particles, and is preferably 80% by mass or less, more preferably 75% by mass or less, relative to the total mass of the core-shell particles.

[0140] <10> The oil-in-water emulsion composition according to any one of <1> to <9>, wherein the content of the oil in a liquid state at 25°C in the core-shell particles is preferably 0.5% by mass or more, more preferably 1% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 25% by mass or less, more preferably 20% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <11> The oil-in-water emulsion composition according to any one of <1> to <10>, wherein the mass ratio of component (a1) to component (a2) [(a1) / (a2)] is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, and preferably 2 or less, more preferably 1 or less, even more preferably 0.5 or less.

[0141] <12> The oil-in-water emulsion composition according to any one of <1> to <11>, wherein the core of the core-shell particle preferably further contains (a3) ​​a powder dispersant, more preferably one or more selected from polyether-modified silicone, polyhydroxy fatty acid, dipentaerythrityl tri-polyhydroxy fatty acid, and diglycerin difatty acid ester. <13> The oil-in-water emulsion composition according to any one of <1> to <12>, wherein component (b1) is preferably one or more selected from fatty acid salts, alkyl sulfate salts, polyoxyethylene alkyl ether sulfate salts, N-acylsarcosinates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, dialkyl sulfosuccinates, N-alkyloylmethyl taurines, and N-acyl glutamates; more preferably one or more selected from N-acyl glutamates having an acyl group of 12 to 24 carbon atoms, N-alkyloylmethyl taurines having an alkyloyl group of 12 to 24 carbon atoms, fatty acid salts having 12 to 24 carbon atoms, and polyoxyethylene alkyl ether phosphates having 12 to 24 carbon atoms; even more preferably one or more selected from N-acyl glutamates having an acyl group of 12 to 24 carbon atoms, and N-alkyloylmethyl taurines having an alkyloyl group of 12 to 24 carbon atoms.

[0142] <14> The oil-in-water emulsion composition according to any one of <1> to <13>, wherein the content of component (b1) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 3% by mass or less, more preferably 1.5% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <15> The oil-in-water emulsion composition according to any one of <1> to <14>, wherein component (b2) is preferably one or more selected from higher alcohols, ceramides, linear saturated fatty acids having 10 to 24 carbon atoms, polyhydric alcohol mono-C10-24 fatty acid esters, sorbitan di-C10-24 fatty acid esters, and polyhydric alcohol mono-C10-24 alkyl ethers, more preferably one or more selected from monohydric alcohols having 10 to 24 carbon atoms, natural ceramides, pseudo-ceramides, linear saturated fatty acids having 12 to 24 carbon atoms, glycerin mono-C10-24 fatty acid esters, sorbitan mono-C10-24 fatty acid esters, and sorbitan di-C10-24 fatty acid esters, and even more preferably one or more selected from monohydric alcohols having 10 to 24 carbon atoms, glycerin mono-C10-24 fatty acid esters, and sorbitan di-C10-24 fatty acid esters.

[0143] <16> The oil-in-water emulsion composition according to any one of <1> to <15>, wherein the content of the hydrophobic amphiphilic substance of component (b2) in the core-shell particles is preferably 0.025% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.075% by mass or more, and even more preferably 0.1% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <17> The oil-in-water emulsion composition according to any one of <1> to <16>, wherein the core-shell particles preferably have an α-gel structure.

[0144] <18> The oil-in-water emulsion composition according to any one of <1> to <17>, wherein the core-shell particles preferably contain one or more components selected from (b3) an oil-based thickener and (b4) water, more preferably further contain at least component (b3), and even more preferably contain components (b3) to (b4). <19> The oil-in-water emulsion composition according to <18>, wherein the component (b3) is preferably one or more selected from a sugar fatty acid ester-based oil-based thickener, polyglyceryl isostearate, glyceryl behenate / eicosanedioate, and an organically modified clay mineral, more preferably a sugar fatty acid ester-based oil-based thickener, even more preferably a dextrin fatty acid ester, even more preferably one or more selected from dextrin myristate, dextrin palmitate, dextrin stearate, dextrin palmitate / 2-ethylhexanoate, and dextrin palmitate / hexyldecanoate.

[0145] <20> The oil-in-water emulsion composition according to <18> or <19>, wherein the content of the oil-based thickener in the core-shell particles is preferably 0.0075% by mass or more, more preferably 0.01% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <21> The oil-in-water emulsion composition according to any one of <1> to <20>, wherein the average particle size of the core-shell particles is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.075 μm or more, even more preferably 0.1 μm or more, and is preferably 15 μm or less, more preferably 7.5 μm or less, even more preferably 5 μm or less, even more preferably 2.5 μm or less, and even more preferably 0.5 μm or less.

[0146] <22> The oil-in-water emulsion composition according to any one of <1> to <21>, wherein the content of the core-shell particles is preferably 3% by mass or more, more preferably 7.5% by mass or more, even more preferably 12.5% ​​by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 27.5% by mass or less, even more preferably 20% by mass or less, relative to the total mass of the oil-in-water emulsion composition.

[0147] <23> The oil-in-water emulsion composition according to any one of <1> to <22>, wherein the component (e1) is preferably a hydrophobized fine particle metal oxide, more preferably one or more fine particle metal oxides selected from zinc oxide, titanium oxide, cerium oxide, iron oxide, and chromium oxide that have been hydrophobized, even more preferably one or more fine particle metal oxides selected from zinc oxide, titanium oxide, and cerium oxide that have been hydrophobized, even more preferably one or more fine particle metal oxides selected from zinc oxide and titanium oxide that have been hydrophobized, and even more preferably hydrophobized fine particle titanium oxide. <24> The oil-in-water emulsion composition according to any one of <1> to <23>, wherein the hydrophobization treatment of component (e1) is preferably a hydrophobization treatment selected from treatment with a fluorine compound, silicone treatment, silicone resin treatment, pendant treatment, treatment with a silane coupling agent, treatment with a titanium coupling agent, treatment with an oil, treatment with an N-acylated lysine, treatment with polyacrylic acid, treatment with a metal soap, treatment with an amino acid, treatment with an inorganic compound, plasma treatment, mechanochemical treatment, treatment with a silane compound, and treatment with a silazane compound, and more preferably a hydrophobization treatment selected from treatment with a silicone resin, treatment with a silane compound, treatment with a silazane compound, and treatment with a metal soap.

[0148] <25> The oil-in-water emulsion composition according to any one of <1> to <24>, wherein the content of component (e1) is preferably 3% by mass or more, more preferably 5% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 25% by mass or less, more preferably 22.5% by mass or less, even more preferably 20% by mass or less, even more preferably 18% by mass or less, and even more preferably 15% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <26> The oil-in-water emulsion composition according to any one of <1> to <25>, wherein component (c4) is preferably at least one or more selected from the group consisting of a poly(meth)acrylamide aqueous thickener, a polysaccharide aqueous thickener, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, a carboxyvinyl polymer, and an acrylic acid / alkyl acrylate copolymer, more preferably at least a poly(meth)acrylamide aqueous thickener, and even more preferably a combination of a poly(meth)acrylamide aqueous thickener and a polysaccharide aqueous thickener.

[0149] <27> The oil-in-water emulsion composition according to any one of <1> to <26>, wherein the content of component (c4) is, relative to the total mass of the oil-in-water emulsion composition, preferably 0% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, and even more preferably 0.85% by mass or more, and is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, even more preferably 1.5% by mass or less, and even more preferably 1% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <28> The oil-in-water emulsion composition according to any one of <1> to <27>, preferably further containing one or more selected from (c2) a volatile medium other than water, (c3) a polyhydric alcohol, (d2) a second surfactant, (d3) a second powder dispersant, and (d4) an amphiphilic solid fat, more preferably further containing component (d2), even more preferably further containing components (d2) and (d4), and even more preferably further containing component (c3) and components (d2) to (d4).

[0150] <29> The oil-in-water emulsion composition according to <28>, comprising (d1) a second oil that is liquid at 25° C., wherein component (d1) is preferably a non-volatile oil, more preferably one or two or more non-volatile oils selected from non-volatile hydrocarbon oils, non-volatile silicone oils, non-volatile fatty acid ester oils, and C12-15 alkyl benzoates. <30> The oil-in-water emulsion composition according to <28> or <29>, wherein component (d2) is preferably one or two or more selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants, more preferably nonionic surfactants, even more preferably one or two or more selected from sorbitan fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene alkyl ethers, and polyoxyalkylene hydrogenated castor oils, even more preferably polyoxyalkylene sorbitan fatty acid esters.

[0151] <31> The oil-in-water emulsion composition according to any one of <28> to <30>, wherein the content of component (d2) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 5% by mass or less, more preferably 2.5% by mass or less, relative to the total mass of the oil-in-water emulsion composition. <32> The oil-in-water emulsion composition according to any one of <28> to <31>, wherein component (c3) is preferably one or more selected from glycols and glycerins, more preferably a glycol, and even more preferably an alkylene glycol.

[0152] <33> The oil-in-water emulsion composition according to any one of <1> to <32>, wherein the total content of the liquid phase in the oil-in-water emulsion composition is preferably 55% by mass or more, more preferably 60% by mass or more, based on the total mass of the oil-in-water emulsion composition, and is preferably 95% by mass or less, more preferably 90% by mass or less, based on the total mass of the oil-in-water emulsion composition. <34> The oil-in-water emulsion composition according to any one of <1> to <32>, wherein the mass ratio of the core-shell particles to the liquid phase in the oil-in-water emulsion composition [(core-shell particles) / (liquid phase)] is preferably 0.01 or more, more preferably 0.1 or more, and preferably 0.5 or less, more preferably 0.3 or less.

[0153] <35> The oil-in-water emulsion composition according to any one of <1> to <34>, wherein the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition is preferably 4% by mass or more, more preferably 8% by mass or more, even more preferably 11% by mass or more, relative to the total mass of the oil-in-water emulsion composition, and is preferably 32.5% by mass or less, more preferably 30% by mass or less, even more preferably 27.5% by mass or less, even more preferably 25% by mass or less, even more preferably 22% by mass or less, even more preferably 20% by mass or less, even more preferably 18% by mass or less, relative to the total mass of the oil-in-water emulsion composition.

[0154] <36> The oil-in-water emulsion composition according to any one of <1> to <34>, wherein the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition is 11% by mass or more, based on the total mass of the oil-in-water emulsion composition. <37> The oil-in-water emulsion composition according to any one of <1> to <34>, wherein the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition is 11% by mass or more and 25% by mass or less, based on the total mass of the oil-in-water emulsion composition. <38> The oil-in-water emulsion composition according to any one of <1> to <26> and <28> to <34>, wherein the content of component (c4) is 0.5% by mass or more and 1.5% by mass or less, based on the total mass of the oil-in-water emulsion composition, and the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition is 11% by mass or more and 25% by mass or less, based on the total mass of the oil-in-water emulsion composition.

[0155] <39> The oil-in-water emulsion composition according to any one of <1> to <38>, wherein the mass ratio of the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition to the total content of all oil agents that are liquid at 25°C in the oil-in-water emulsion composition (preferably the total of components (a2) and (d1)) [(total hydrophobized UV scattering agents in the oil-in-water emulsion composition) / (total oil agents that are liquid at 25°C in the oil-in-water emulsion composition)] is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and is preferably 1 or less, more preferably 0.75 or less, even more preferably 0.5 or less, even more preferably 0.48 or less.

[0156] <40> The oil-in-water emulsion composition according to any one of <1> to <38>, wherein the mass ratio of the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition to the total content of all oil agents that are liquid at 25°C in the oil-in-water emulsion composition (preferably the total of components (a2) and (d1)) [(total hydrophobized UV scattering agents in the oil-in-water emulsion composition) / (total oil agents that are liquid at 25°C in the oil-in-water emulsion composition)] is 0.3 or more and 0.48 or less. <41> The oil-in-water emulsion composition according to any one of <1> to <26> and <28> to <38>, wherein the content of component (c4) is from 0.5% by mass to 1.5% by mass, relative to the total mass of the oil-in-water emulsion composition; and the mass ratio of the content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition to the total content of all oil agents in the oil-in-water emulsion composition that are liquid at 25°C (preferably the sum of components (a2) and (d1)) [(total hydrophobized UV scattering agents in the oil-in-water emulsion composition) / (total oil agents in the oil-in-water emulsion composition that are liquid at 25°C)] is from 0.3 to 0.48. <42> The oil-in-water emulsion composition according to any one of <1> to <25> and <28> to <38>, wherein component (c4) is a combination of a poly(meth)acrylamide aqueous thickener and a polysaccharide aqueous thickener, the content of component (c4) is 0.5% by mass or more and 1.5% by mass or less, relative to the total mass of the oil-in-water emulsion composition, and the mass ratio of the content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition to the total amount of oil agents in the oil-in-water emulsion composition that are liquid at 25°C (preferably the total amount of components (a2) and (d1)) [(total hydrophobized UV scattering agents in the oil-in-water emulsion composition) / (total oil agents in the oil-in-water emulsion composition that are liquid at 25°C)] is 0.3 or more and 0.48 or less.

[0157] <43> The oil-in-water emulsion composition according to any one of <1> to <42>, wherein the mass ratio of the total water content in the oil-in-water emulsion composition to the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition [(water in the oil-in-water emulsion composition) / (total hydrophobized UV scattering agents in the oil-in-water emulsion composition)] is preferably 1 or more, more preferably 1.4 or more, even more preferably 1.8 or more, and is preferably 5.5 or less, more preferably 4.5 or less, even more preferably 3.5 or less.

[0158] <44> The oil-in-water emulsion composition according to any one of <1> to <42>, wherein the mass ratio of the total water content in the oil-in-water emulsion composition to the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition [(water in the oil-in-water emulsion composition) / (total hydrophobized UV scattering agents in the oil-in-water emulsion composition)] is 1.4 or more and 4.5 or less.

[0159] <45> The oil-in-water emulsion composition according to any one of <1> to <44>, wherein the mass ratio of the total content of all oil agents that are liquid at 25°C in the oil-in-water emulsion composition (preferably the sum of components (a2) and (d1)) to the total content of water in the oil-in-water emulsion composition [(all oil agents that are liquid at 25°C in the oil-in-water emulsion composition) / (water in the oil-in-water emulsion composition)] is preferably from 0.3 to 2, more preferably from 0.5 to 1.5.

[0160] <46> The oil-in-water emulsion composition according to any one of <1> to <45>, wherein the total content of the ultraviolet absorbers is, relative to the total mass of the oil-in-water emulsion composition, preferably from 0 to 20% by mass, more preferably from 0 to 5% by mass, even more preferably from 0 to 1% by mass, even more preferably from 0 to 0.1% by mass, even more preferably from 0 to 0.01% by mass, and still more preferably 0% by mass.

[0161] <47> The oil-in-water emulsion composition according to any one of <1> to <45>, wherein the total content of the ultraviolet absorbers is 0% by mass, based on the total mass of the oil-in-water emulsion composition.

[0162] <48> The oil-in-water emulsion composition according to any one of <1> to <47>, wherein the core-shell particles are dispersed in the aqueous phase of the oil-in-water emulsion composition, and component (e1) is dispersed in the oil phase of the oil-in-water emulsion composition.

[0163] <49> The oil-in-water emulsion composition according to any one of <1> to <48>, which is a cosmetic product, preferably a sunscreen, foundation, makeup base, lotion, emulsion, cream, gel, serum, or sheet-type cosmetic product, and more preferably a sunscreen. <50> The oil-in-water emulsion composition according to any one of <1> to <49>, which is preferably for skin, more preferably for skin excluding the scalp, and even more preferably for the face, body, hands, and feet.

[0164] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, the components used in these examples are as shown in Table 1 below.

[0165]

[0166] Various measurements and evaluations of the core-shell particles and the cosmetic were carried out by the following methods.

[0167] (Average particle size of core-shell particles) The average particle size (volume median diameter: D50) of the core-shell particles was measured using a dynamic light scattering particle size distribution analyzer "LB-500" manufactured by Horiba, Ltd. Three drops of an aqueous dispersion of the core-shell particles were dropped into a 1 cm square measurement cell, and then diluted with approximately 2 mL of ion-exchanged water to prepare a measurement sample, which was used to measure the average particle size at 25°C (N=1). The refractive index of the sample was 1.582, and the refractive index of the dispersion medium was 1.333 for water.

[0168] (α-Gel Structure of Core-Shell Particles) The core-shell particles were subjected to wide-angle X-ray diffraction, and when a sharp diffraction peak appeared at a Bragg angle of approximately 21 to 22°, it was determined that the particles had an α-gel structure.

[0169] (Imaging of the cross section of core-shell particles) The cosmetic of Example 3 was aspirated using a glass capillary, then rapidly frozen and fractured so that the cross section could be observed. The sample was subjected to a sublimation treatment at -90°C for 20 minutes to prepare a specimen for observation. This specimen for observation was observed and imaged using a cryo-SEM at an accelerating voltage of 1.0 kV and a magnification of 30,000 times. The captured SEM image is shown in Figure 1. As shown in Figure 1, a core portion in which (a1) a hydrophobized ultraviolet scattering agent was dispersed in (a2) a liquid oil at 25°C was encapsulated in a shell portion having α-gel.

[0170] (UV Protection Effect (SPF Value)) A cosmetic was applied to a PMMA plate (PMMA Plate HD6, manufactured by Helioscreen Cosmetic Science) at a concentration of 1.3 mg / cm. 2The sample was uniformly applied for 1 minute so that the absorbance was 100% and then dried in a cool, dark place for 15 minutes. After drying, the transmittance (%) of the absorption spectrum was measured at a total of nine points on the square PMMA plate, namely the midpoint, each vertex, and the midpoint of the side connecting the vertices, using an SPF analyzer (SPF Analyzer UV-2000S, manufactured by Labsphere), and the average of the nine points was calculated. The SPF value was calculated from this transmittance (%) and evaluated according to the following criteria. The higher the SPF value, the higher the ultraviolet protection effect, and a rating of C was considered to be acceptable.

[0171] (Evaluation criteria for UV protection effect) A: 55 or more B: 50 or more to less than 55 C: 40 or more to less than 50 D: 30 or more to less than 40 E: Less than 30

[0172] (No white cast) Three expert panelists applied 2 mg / cm of cosmetic product to a 3 cm square area on the inside of the forearm. 2 After 20 minutes had passed from the application of the cosmetic composition at 25°C and 40% RH, a visual sensory evaluation was performed to determine whether or not the applied area appeared white. An average value was calculated from the following evaluation values, and the average value of the three judges was converted into a score of A to E below. The higher the average value, the less likely white cast would occur, and a score of C was considered acceptable.

[0173] Evaluation value (absence of whitish cast) 4: No whitish cast at all. 3: No whitish cast. 2: Slightly whitish cast, but within the acceptable range. 1: Whitish cast. Table converting evaluation value to score (absence of whitish cast) A: 3.5 or more and 4.0 or less B: 3.0 or more and less than 3.5 C: 2.0 or more and less than 3.0 D: 1.6 or more and less than 2.0 E: 1.0 or more and less than 1.6

[0174] (Irritation resistance) Three expert panelists washed their faces, allowed them to acclimate for 15 minutes, and then applied 2 mg / cm of the cosmetic to the lower half of the face. 2The sample was applied and dried at 25°C and 45% RH for 15 minutes. Itching caused by fiber irritation was evaluated with reference to the evaluation method described in <Evaluation Case 2> of JP 2023-20017 A. Itching was quantified by expert panelists marking the line between 1 and 10 on the evaluation sheet, with 1 representing no itching at all and 10 representing the most itchy sensation imaginable. The average VAS evaluation before and after application was calculated, and the inhibition rate was calculated by dividing the VAS value after application by the VAS value before application, to calculate the average inhibition rate for the three subjects. The average value was converted into a score from A to E. It can be said that the smaller the average value, the less irritation there is when rubbed, and a rating of C was considered acceptable.

[0175] Table for converting evaluation values ​​into scores (irritation resistance) A: 0.1 or more and less than 0.6 B: 0.6 or more and less than 0.7 C: 0.7 or more and less than 0.8 D: 0.8 or more and less than 0.85 E: 0.85 or more and less than 1.0

[0176] (Moisturizing Feeling (Sensory Evaluation)) Three expert panelists applied 2 mg / cm of a cosmetic to a 3 cm square area on the inside of the forearm at 20°C and 40% RH. 2 The coating was applied and allowed to dry for 15 minutes. A sensory evaluation was performed on the moisturizing sensation based on the feel of the coating film after drying. An average value was calculated from the following evaluation values, and the average value of the three judges was converted into a score of A to E below. The higher the average value, the more moisturizing sensation was felt, and a score of C was considered to be acceptable.

[0177] Evaluation value (moisturizing feeling) 4: Very high moisturizing feeling. 3: High moisturizing feeling. 2: Neither moisturizing feeling nor moisturizing feeling. 1: Low moisturizing feeling. Table converting evaluation value to score (moisturizing feeling) A: 4.0 or more and 5.0 or less B: 3.0 or more and less than 4.0 C: 2.0 or more and less than 3.0 D: 1.6 or more and less than 2.0 E: 1.0 or more and less than 1.6

[0178] (Moisturizing property (skin test)) A moisturizing test was carried out on the cosmetics of Example 3 and Comparative Example 1. That is, after washing the face, the subject was allowed to acclimate for 15 minutes at 20°C and 40% RH, and the moisture content of the stratum corneum before application was measured using a Corneometer (Corneometer CM825, manufactured by Courage+Khazaka). The cosmetic of Example 3 or Comparative Example 1 was applied to half of the face of the subject at a concentration of 2 mg / cm.2 The moisture content of the stratum corneum was measured 8 hours later. The moisture content of the stratum corneum before application was subtracted from the moisture content of the stratum corneum 8 hours later to calculate the change in moisture content 8 hours after application. The results are shown below. Example 3: 8.52 Comparative Example 1: 1.66

[0179] (Ease of washing off) Three expert panelists applied 2 mg / cm of cosmetic to an area of ​​3 cm square on the inside of the forearm. 2 After application, the cosmetic was allowed to dry at room temperature for 15 minutes, and then washed off with soap. After washing, a sensory evaluation was conducted on a four-point scale from 1 to 4 to determine whether any white residue remained on the skin. The average value of the three judges was converted into a score of A to E as follows:

[0180] Evaluation value (ease of rinsing) 4: No white residue at all. 3: No white residue. 2: Some white residue is felt, but within the acceptable range. 1: White residue is felt. Table converting evaluation value to score (ease of rinsing) A: 4.0 or more and 5.0 or less B: 3.0 or more and less than 4.0 C: 2.0 or more and less than 3.0 D: 1.6 or more and less than 2.0 E: 1.0 or more and less than 1.6

[0181] (Formulation feasibility) After production, the formulation was observed under a microscope to confirm whether it maintained its O / W form. If it was an O / W type where titanium oxide was observed in the internal phase, it was rated as ◯, and if it was a W / O type where titanium oxide was observed in the external phase, it was rated as ×, meaning that it could not be formulated due to phase inversion. O / W: ◯ W / O: ×

[0182] (Storage Stability) A storage stability test was conducted on the cosmetics of Examples 1 to 5, 11 to 16 and Comparative Examples 1 to 4. 50 g of the cosmetic was placed in a 50 mL glass bottle, sealed, and stored at 50°C for one month. The viscosity was then measured to confirm any change in viscosity from immediately after production. A TVB-10 viscometer manufactured by Toki Sangyo Co., Ltd. was used for viscosity measurement, and the measurement conditions were rotor No. 4, 6 rpm, 1 min, and 25°C. The amount of change in viscosity from immediately after production was scored from A to E.

[0183] Evaluation value (storage stability) A: Viscosity change immediately after application is less than 10,000 mPa·s B: Viscosity change immediately after application is 10,000 mPa·s or more and less than 40,000 mPa·s C: Viscosity change immediately after application is 40,000 mPa·s or more and less than 70,000 mPa·s D: Viscosity change immediately after application is 70,000 mPa·s or more and less than 110,000 mPa·s E: Viscosity change immediately after application is 110,000 mPa·s or more or separation occurs

[0184] (Film Thickness Measurement) Film thickness measurements were carried out for the cosmetics of Example 3 and Comparative Example 1. That is, equal amounts of the cosmetics of Example 3 and Comparative Example 1 were each applied to commercially available artificial leather and allowed to dry. The coating film was cut along with the artificial leather so that the cross section could be observed, and the film was observed under a microscope, and the average film thickness was calculated. The results are shown in Figures 2 and 3. It was observed that the coating film was thicker when the cosmetic of Example 3 was used.

[0185] Example 1: Oil-in-Water Sunscreen Cosmetic A sunscreen cosmetic was produced using the ingredients shown in Table 2 in the following manner. 1) Production of Core-Shell Particles A titanium oxide dispersion (a composition of a mixture of fine titanium oxide particles, aluminum hydroxide, and stearic acid, caprylic / capric triglyceride, and polyhydroxystearic acid), dextrin palmitate, and the "shell component" in Table 2 were mixed and heated to 80-90°C with stirring to obtain an oil phase. This oil phase and the "aqueous phase component 1" in Table 2 were used to form an oil-in-water emulsion in accordance with the method described in JP 2017-7969 A. Specifically, the emulsion droplets were refined using a homomixer so that the average particle size of the core-shell particles reached the desired value (0.31 μm), and the emulsion was then continuously cooled to 40°C while stirring to obtain an aqueous dispersion of core-shell particles. The average particle size of the core-shell particles was measured, and the α-gel structure was confirmed. The results are shown in Table 2.

[0186] 2) Production of Oil-in-Water Sunscreen Cosmetic The aqueous dispersion of core-shell particles obtained above was added at 25°C to a blending tank containing purified water (purified water designated "Aqueous Phase Component 2" in Table 2). An aqueous phase was prepared by adding "Aqueous Phase Component 2 (excluding phenoxyethanol and purified water)" in Table 2. Meanwhile, "Oil Phase Component 2 (excluding Titanium Dioxide Microparticle, Aluminum Hydroxide, and Stearic Acid Mixture (2))" in Table 2 was heated, dissolved, and mixed at a temperature of approximately 60°C, to which was added "Titanium Dioxide Microparticle, Aluminum Hydroxide, and Stearic Acid Mixture (2)" in Table 2, and dispersed using a disperser to prepare an oil phase. This oil phase was cooled to 35°C, added to the aqueous phase obtained above, and the mixture was stirred using a homomixer. Phenoxyethanol was then added, followed by fine emulsification using a homomixer to produce an oil-in-water sunscreen cosmetic, which was then subjected to various evaluations. The results are shown in Table 2.

[0187] (Examples 2 to 13, Comparative Example 3 Oil-in-water sunscreen cosmetics) Sunscreen cosmetics were produced and various evaluations were carried out in the same manner as in Example 1, except for using the amounts of ingredients shown in Tables 2 to 4 and 6 for Examples 2 to 13. The results are shown in Tables 2 to 4 and 6.

[0188] Example 14 Oil-in-water sunscreen cosmetic A sunscreen cosmetic was produced in the same manner as in Example 3, except that the stirring speed during the micronization treatment using a homomixer was adjusted so that the average particle size of the core-shell particles would be 0.25 μm, and various evaluations were carried out. The results are shown in Table 5.

[0189] Example 15 Oil-in-water sunscreen cosmetic A sunscreen cosmetic was produced in the same manner as in Example 3, except that the stirring speed during the micronization treatment using a homomixer was adjusted so that the average particle size of the core-shell particles would be 0.41 μm, and various evaluations were carried out. The results are shown in Table 5.

[0190] (Comparative Examples 1 and 2 Oil-in-water Sunscreen Cosmetics) Sunscreen cosmetics of Comparative Examples 1 and 2 were produced according to standard methods using the amounts of ingredients shown in Table 6, and various evaluations were carried out. The results are shown in Table 6.

[0191] Here, the numbers in parentheses in each table indicate the content of the active ingredient. Furthermore, since SIMULGEL EG QD contains, in addition to sodium acrylate-sodium acryloyldimethyltaurate copolymer (37.5%), isohexadecane (22.5%), water (30%), sorbitan oleate (2.5%), and polysorbate 80 (7.5%), the total content of oils that are liquid at 25°C, the mass ratio [(total hydrophobized UV scattering agent in the oil-in-water emulsion composition) / (total oils that are liquid at 25°C in the oil-in-water emulsion composition)], the mass ratio [(water in the oil-in-water emulsion composition) / (total hydrophobized UV scattering agent in the oil-in-water emulsion composition)], and the mass ratio [(total oils that are liquid at 25°C in the oil-in-water emulsion composition) / (water in the oil-in-water emulsion composition)] were calculated taking into account the isohexadecane (22.5%) and water (30%) carried over from this composition.

[0192]

[0193]

[0194]

[0195]

[0196]

[0197] (Comparative Example 4: Cosmetic) A cosmetic was prepared according to the description of Preparation Example 4 in JP 2022-184817 A so as to have the composition shown in Table 7 below. Next, a cosmetic was produced according to the formulation shown in Table 8 and in accordance with the method of "2) Production of oil-in-water sunscreen cosmetic" in Example 1, and evaluated. The results are shown in Table 8.

[0198]

[0199]

[0200] (Formulation Example 1: Oil-in-water sunscreen cosmetic) The oil-in-water sunscreen cosmetic of Formulation Example 1 was produced by a conventional method according to the formulation shown in Table 9. When evaluated for UV protection effect, absence of white cast, resistance to irritation, moisturizing feel, ease of rinsing, feasibility as a formulation, and storage stability, the oil-in-water sunscreen cosmetic of Formulation Example 1 was found to be excellent in all respects.

[0201]

Claims

1. An oil-in-water emulsion composition comprising core-shell particles whose core comprises the following components (a1) and (a2): (a1) a hydrophobized ultraviolet scattering agent, and (a2) an oil solution that is liquid at 25°C, and whose shell comprises the following components (b1) and (b2): (b1) an anionic surfactant, and (b2) a hydrophobic amphiphilic substance; (e1) a second hydrophobized ultraviolet scattering agent; and (c4) an aqueous thickener, in which the core-shell particles and (e1) the second hydrophobized ultraviolet scattering agent are dispersed.

2. The oil-in-water emulsion composition according to claim 1, wherein component (a1) is a hydrophobically treated metal oxide fine particle.

3. The oil-in-water emulsion composition according to claim 1 or 2, wherein the content of component (a1) is 0.1% by mass or more and 40% by mass or less based on the total mass of the core-shell particles.

4. The oil-in-water emulsion composition according to any one of claims 1 to 3, wherein the mass ratio of component (a1) to component (a2) [(a1) / (a2)] is 0.01 or more and 2 or less.

5. The oil-in-water emulsion composition according to any one of claims 1 to 4, wherein the average particle size of the core-shell particles is 0.01 µm or more and 15 µm or less.

6. The oil-in-water emulsion composition according to any one of claims 1 to 5, wherein the core-shell particles have an α-gel structure.

7. The oil-in-water emulsion composition according to any one of claims 1 to 6, further comprising (d1) a second oil agent that is liquid at 25°C.

8. The oil-in-water emulsion composition according to any one of claims 1 to 7, wherein the content of the core-shell particles is 3% by mass or more and 35% by mass or less, based on the total mass of the oil-in-water emulsion composition.

9. The oil-in-water emulsion composition according to any one of claims 1 to 8, wherein the total content of the ultraviolet absorbers is from 0% by mass to 20% by mass, based on the total mass of the oil-in-water emulsion composition.

10. The oil-in-water emulsion composition according to any one of claims 1 to 9, wherein the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition is 11 mass% or more, based on the total mass of the oil-in-water emulsion composition.

11. The oil-in-water emulsion composition according to any one of claims 1 to 10, wherein the content mass ratio of the total of all hydrophobized UV scattering agents in the oil-in-water emulsion composition to the total of all oil agents in the oil-in-water emulsion composition that are liquid at 25°C [(total hydrophobized UV scattering agents in the oil-in-water emulsion composition) / (total oil agents in the oil-in-water emulsion composition that are liquid at 25°C)] is 0.1 or more and 0.75 or less.

12. The oil-in-water emulsion composition according to any one of claims 1 to 11, wherein the mass ratio of the total water content in the oil-in-water emulsion composition to the total content of all hydrophobized UV scattering agents in the oil-in-water emulsion composition [(water in the oil-in-water emulsion composition) / (total hydrophobized UV scattering agents in the oil-in-water emulsion composition)] is 1 or more and 5.5 or less.

13. The oil-in-water emulsion composition according to any one of claims 1 to 12, wherein the total content of the ultraviolet absorbers is 0% by mass, based on the total mass of the oil-in-water emulsion composition.

14. The oil-in-water emulsion composition according to any one of claims 1 to 13, wherein the core-shell particles are dispersed in the aqueous phase of the oil-in-water emulsion composition, and component (e1) is dispersed in the oil phase of the oil-in-water emulsion composition.

15. The oil-in-water emulsion composition according to any one of claims 1 to 14, which is a sunscreen cosmetic.

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