Sunblock cosmetic

Abstract

To provide sunscreen cosmetics having resistance to physical rubbing.SOLUTION: Sunscreen cosmetics are a Pickering emulsion that contains (A) particulate metal oxides and (B) hydrophilic film-forming polymers.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sunscreen cosmetic.

Background Art

[0002] External compositions containing metal oxide powders are widely known. For example, powders obtained by micronizing metal oxides such as titanium oxide, zinc oxide, zirconium oxide, and cerium oxide have the function of scattering, absorbing, and reflecting ultraviolet rays, and thus are blended into external compositions for sunscreen, such as those for sunscreen, as ultraviolet ray shielding materials (for example, Patent Document 1). In addition, pickering emulsions stabilized by adsorbing metal oxides such as silica at the emulsion interface are known (for example, Patent Document 2).

[0003] The present inventors have disclosed the research result that, as a characteristic of a preparation using a pickering emulsion, when it comes into contact with sweat (ions), the interfacial film of the powder aggregates, so that ultraviolet rays are absorbed more efficiently and the SPF increases (Non-Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, one of the physical properties required for sunscreen cosmetics is resistance to physical rubbing. Therefore, an object of the present invention is to provide a sunscreen cosmetic having resistance to physical rubbing.

Means for Solving the Problems

[0007] The inventors of the present invention made intensive studies by making use of the finding that one of the characteristics of a Pickering emulsion formulation is that it forms a film that is resistant to physical rubbing. As a result, they found that a Pickering emulsion containing fine particle metal oxide and a hydrophilic film-forming polymer has more resistance to physical rubbing, and completed the present invention.

[0008] That is, the present invention for solving the above problems is (A) fine particle metal oxide and (B) a hydrophilic film-forming polymer, and is a Pickering emulsion is a sunscreen cosmetic The sunscreen cosmetic of the present invention is excellent in resistance to rubbing.

[0009] In a preferred form of the present invention, the molecular weight of the film-forming polymer is 2,000 to 20,000.

[0010] In a preferred form of the present invention, the film-forming polymer is an acrylic polymer.

[0011] In a preferred form of the present invention, the fine particle metal oxide is fine particle titanium oxide.

[0012] In a preferred form of the present invention, it further contains (C) silica-based fine particles.

[0013] In a preferred form of the present invention, the (C) is silylated silica.

[0014] In a preferred form of the present invention, the sunscreen cosmetic substantially does not contain a surfactant.

[0015] In a preferred embodiment of the present invention, the sunscreen cosmetic is of the O / W type.

[0016] In a preferred embodiment of the present invention, the sunscreen cosmetic is formulated with an aqueous dispersion of fine particle metal oxide obtained by premixing the above (A) and the above (B).

[0017] Further, the present invention for solving the above problems is (A) Fine particle metal oxide, and (B) A hydrophilic film-forming polymer, and preparing an aqueous dispersion of fine particle metal oxide containing the same, mixing an aqueous phase containing the aqueous dispersion and an oil phase to prepare a pickering emulsion, which is a method for producing a sunscreen cosmetic.

Effect of the Invention

[0018] The sunscreen cosmetic of the present invention is excellent in physical rubbing resistance.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0020] The sunscreen cosmetic of the present invention essentially comprises (A) fine particle metal oxide and (B) a hydrophilic film-forming polymer. Hereinafter, each component will be described in detail.

[0021] (1) (A) Fine particle metal oxide The fine particle metal oxide in the present invention refers to a metal oxide having an average primary particle diameter in the range of 10 to 100 nm as observed by an electron microscope. The average primary particle diameter of the fine particle metal oxide is preferably 5 to 80 nm, more preferably 5 to 50 nm.

[0022] The type of metal oxide in the fine particle metal oxide is not particularly limited, and examples thereof include titanium oxide, zinc oxide, iron oxide, zirconium oxide, cerium oxide, etc. Titanium oxide and zinc oxide are preferable as the metal oxide. The surface of the fine particle metal oxide may be coated with an inorganic compound such as silica or alumina, or an organic compound such as an aliphatic metal soap or silicone.

[0023] The fine particle metal oxide can be produced by a conventional method such as a method of thermally decomposing a metal salt in the gas phase, but commercially available products that are widely available may also be used.

[0024] The content of the fine particle metal oxide is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, still more preferably 0.1 to 8% by mass, and particularly preferably 0.5 to 5% by mass with respect to the total amount of the sunscreen cosmetic.

[0025] As will be described later, in the sunscreen cosmetic of the present invention, the fine particle metal oxide of (A) does not necessarily have to be particles for adsorbing at the interface between the aqueous phase and the oil phase to form a Pickering emulsion, and may contain particles for separately forming a Pickering emulsion. On the other hand, the fine particle metal oxide of (A) may contribute to the formation of a Pickering emulsion.

[0026] (2) (B) Hydrophilic film-forming polymer In the present specification, "hydrophilic" means the property of dissolving or dispersing in water. Also, "film-forming polymer" means a polymer having film-forming properties when dried.

[0027] The type of the hydrophilic film-forming polymer is not particularly limited, and examples thereof include vinyl polymers such as polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone, and vinyl acetate-vinyl pyrrolidone copolymer, and acrylic polymers such as polyacrylic acid, sodium polyacrylate, and alkyl acrylate copolymer. Among them, acrylic polymers are preferred, and polyacrylic acid or its salt is more preferred.

[0028] The molecular weight of the film-forming polymer is not particularly limited, but in terms of weight average molecular weight, it is preferably 2,000 to 20,000, more preferably 3,000 to 10,000, and still more preferably 4,000 to 8,000.

[0029] The content of the film-forming polymer is preferably 0.001 to 20% by mass based on the total amount of the sunscreen cosmetic.

[0030] (3) Dosage form The sunscreen cosmetic of the present invention is in the form of a Pickering emulsion. A Pickering emulsion refers to an emulsified composition stabilized using particles. As long as the particles contribute to the emulsion stability, even if other surfactants are contained, it is called a Pickering emulsion, but the sunscreen cosmetic of the present invention preferably substantially does not contain a surfactant. The content of the surfactant is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, particularly preferably 0.01% by mass or less, and most preferably not contained, based on the total amount of the sunscreen cosmetic.

[0031] The Pickering emulsion preparation is excellent in resistance to physical rubbing as compared with an emulsion preparation using a surfactant.

[0032] The particles contributing to the emulsion stability of the Pickering emulsion may be the fine particle metal oxides of (A) or other particles. As the other particles, (C) silica fine particles are preferred.

[0033] When using silica-based fine particles, for example, any of so-called dry silica particles produced by vapor-phase oxidation of silicon halides and so-called wet silica particles produced from water glass or the like may be used. As the dry silica particles, for example, Aerosil series (Nippon Aerosil Co., Ltd.), CAB-O-SIL series (Cabot Corporation), HDK series (Asahi Kasei Wacker Silicone Co., Ltd.) can be used, and as the wet silica powder, for example, Nipsil series (Tokyo Chemical Industry Co., Ltd.), HI-SIL series (PPG) and other commercially available products can be used. The surface of the silica-based fine particles is preferably hydrophobized. The hydrophobized silica-based fine particles can be prepared by reacting the silica-based fine particles with a hydrophobizing agent and adding a hydrophobic group to the hydroxyl groups present on the surface of the powder by covalent bond, or by coating the surface of the silica-based fine particles by physically adhering a hydrophobizing agent.

[0034] Examples of the hydrophobization treatment include a method of treating a metal oxide powder with a hydrophobizing agent such as an organosilicon compound, silicone, hydrocarbon oil, fatty acid, fatty acid amide, fatty acid ester, higher alcohol, polyoxyalkylene compound, etc. Particularly preferably, an organosilicon compound or silicone is used as a hydrophobizing agent to treat metal oxide particles.

[0035] Examples of the organosilicon compound include hexamethyldisilazane, monomethylsilane, dimethylsilane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, palmitysilane, etc. These are used alone or as a mixture of two or more.

[0036] Examples of the silica-based fine particles include hydrophobized silica fine particles having a hydrophobic group such as a monomethylsilyl group, dimethylsilyl group, trimethylsilyl group, octylsilyl group and the like, an alkylsiloxane group such as a dimethylsiloxane group, an alkylpolysiloxane group such as a dimethylpolysiloxane group, an aminoalkylsilyl group, and a methacrylsilyl group added to the surface. Among them, silylated silica having an alkylsilyl group added to the surface is preferable, and silylated silica having a trimethylsilyl group added is more preferable.

[0037] The emulsification form of the sunscreen cosmetic of the present invention is not particularly limited, and may be a W / O type or an O / W type. The sunscreen cosmetic of the present invention is preferably of the O / W type.

[0038] (4) Sunscreen cosmetic As described above, the sunscreen cosmetic of the present invention is a pickering emulsion containing (A) fine particle metal oxide and (B) a hydrophilic film-forming polymer as essential components. The oil phase in the sunscreen cosmetic of the present invention is not particularly limited, and may contain liquid oils and fats, solid oils and fats, waxes, hydrocarbon oils, higher fatty acids, higher alcohols, ester oils, silicone oils and the like.

[0039] Examples of the liquid oils and fats include avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, southern camellia oil, castor oil, linseed oil, safflower oil, cottonseed oil, eno oil, meadowfoam oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, sinagiri oil, Japanese cedar oil, jojoba oil, germ oil, triglyceride, glyceryl trioctanoate, glyceryl triisopalmitate and the like.

[0040] Examples of the solid oils and fats include cocoa butter, coconut oil, horse fat, hydrogenated coconut oil, palm oil, beef tallow, mutton fat, hydrogenated beef tallow, palm kernel oil, lard, beef bone fat, mokuro kernel oil, hydrogenated oil, beef foot fat, mokuro, hydrogenated castor oil and the like.

[0041] Examples of waxes include beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, ibota wax, sperm wax, montan wax, rice bran wax, lanolin, kapok wax, lanolin acetate, liquid lanolin, sugarcane wax, isopropyl lanolin fatty acid, hexyl laurate, reduced lanolin, jojoba wax, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, polyethylene glycol lanolin fatty acid, POE hydrogenated lanolin alcohol ether, etc. Examples of hydrocarbon oils include liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, etc.

[0042] Examples of higher fatty acids include, for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, undecylenic acid, toluic acid, etc.

[0043] Examples of higher alcohols include, for example, cetyl alcohol, stearyl alcohol, behenyl alcohol, batyl alcohol, myristyl alcohol, cetostearyl alcohol, etc.

[0044]

[0045] ​Examples of ester oils include isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, sucrose stearate, sucrose oleate, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glycerin di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, pentaerythritol tetra-2-ethylhexanoate, glycerin tri-2-ethylhexanoate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, glycerin trimyristate, glyceride tri-2-heptylundecanoate, methyl ester of castor oil fatty acid, oleic acid oil, cetostearyl alcohol, acetoglyceride, 2-heptylundecyl palmitate, cetyl palmitate, diisobutyl adipate, 2-octyldodecyl N-lauroyl-L-glutamate, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, 2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, triethyl citrate, etc.

[0046] Examples of silicone oils include linear polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, diphenylsiloxyphenyltrimethicone, and cyclic polysiloxanes such as pentasiloxane, decamethylpolysiloxane, dodecamethylpolysiloxane, tetramethyltetrahydrogenpolysiloxane, etc.

[0047] As the oil phase, one or more of the above-described oils can be used.

[0048] The aqueous phase in the pickering emulsion of the present invention can contain, without particular limitation, components usually used in cosmetics. For example, it preferably contains the following components. Examples of the polyol include polyethylene glycol, glycerin, 1,3-butylene glycol, erythritol, sorbitol, xylitol, maltitol, propylene glycol, dipropylene glycol, diglycerin, isoprene glycol, 1,2-pentanediol, 2,4-hexylene glycol, 1,2-hexanediol, 1,2-octanediol, etc. Among them, glycerin, 1,3-butylene glycol, and sorbitol are preferably mentioned.

[0049] Moreover, it may contain a thickener. Examples of the thickener include xanthan gum, gellan gum, guar gum, quince seed, carrageenan, galactan, gum arabic, pectin, mannan, starch, curdlan, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylhydroxypropylcellulose, chondroitin sulfate, dermatan sulfate, glycogen, heparan sulfate, hyaluronic acid, sodium hyaluronate, tragacanth gum, keratan sulfate, chondroitin, mucitin sulfate, hydroxyethyl guar gum, carboxymethyl guar gum, dextran, kerato sulfate, locust bean gum, succinoglucan, carroninic acid, chitin, chitosan, carboxymethyl chitin, agar, polyvinyl alcohol, polyvinyl pyrrolidone, carboxyvinyl polymer, sodium polyacrylate, polyethylene glycol, sodium acrylate graft starch, stearoxyhydroxypropylmethylcellulose, bentonite, etc.

[0050] The sunscreen cosmetic of the present invention may contain an ultraviolet absorber. Examples of ultraviolet absorbers include benzoic acid derivatives such as para-aminobenzoic acid, monoglycerin ester of para-aminobenzoic acid, ethyl N,N-dipropoxy para-aminobenzoate, ethyl N,N-diethoxy para-aminobenzoate, ethyl N,N-dimethyl para-aminobenzoate, butyl N,N-dimethyl para-aminobenzoate, ethyl N,N-dimethyl para-aminobenzoate, hexyl diethylamino hydroxybenzoyl benzoate; anthranilic acid derivatives such as homomethyl-N-acetylanthranilate; salicylic acid and its sodium salt, amyl salicylate, menthyl salicylate, homomethyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, p-isopropanol phenyl salicylate and other salicylic acid derivatives; cinnamic acid derivatives such as octyl cinnamate, ethyl 4-isopropyl cinnamate, methyl 2,5-diisopropyl cinnamate, ethyl 2,4-diisopropyl cinnamate, methyl 2,4-diisopropyl cinnamate, propyl p-methoxy cinnamate, isopropyl p-methoxy cinnamate, isoamyl p-methoxy cinnamate, 2-ethylhexyl p-methoxy cinnamate (ethylhexyl methoxycinnamate, octyl paramethoxycinnamate), 2-ethoxyethyl-p-methoxy cinnamate (sinoxate), cyclohexyl-p-methoxy cinnamate, ethyl α-cyano-β-phenyl cinnamate, 2-ethylhexyl 2-cyano-3,3-diphenyl acrylate (octocrylene), glyceryl mono-2-ethylhexanoyl-diparamethoxy cinnamate, ferulic acid and its derivatives;Benzophenone derivatives such as 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone (oxybenzone-3), 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone, 2-ethylhexyl-4'-phenyl-benzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, 4-hydroxy-3-carboxybenzophenone; 3-(4'-methylbenzylidene)-d,l-camphor, 3-benzylidene-d,l-camphor; 2-phenyl-5-methylbenzoxazole; 2,2'-hydroxy-5-methylphenylbenzotriazole; 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole; 2-(2'-hydroxy-5'-methylphenylbenzotriazole; dibenzalazine; dianisoylmethane; 5-(3,3-dimethyl-2-norbornylidene)-3-pentan-2-one; dibenzoylmethane derivatives such as 4-t-butylmethoxydibenzoylmethane; octyltriazone; urocanic acid derivatives such as urocanic acid and ethyl urocanate; hydantoin derivatives such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 1-(3,4-dimethoxyphenyl)-4,4-dimethyl-1,3-pentanedione, 2-ethylhexyl dimethoxybenzylidene dioxoimidazolidine propionate; phenylbenzimidazolesulfonic acid, terephthalylidene dicamphorsulfonic acid, droxmetrizole trisiloxane, methyl anthranilate, bisethylhexyloxyphenol methoxyphenyltriazine, rutin and its derivatives, oryzanol and its derivatives are preferably mentioned.;

[0051] In addition, the sunscreen cosmetic of the present invention can contain optional components normally used in cosmetics, as long as the effects of the invention are not impaired, in addition to the above components. Such optional components include, for example, fatty acid soaps (sodium laurate, sodium palmitate, etc.), anionic surfactants such as potassium lauryl sulfate and triethanolamine alkyl sulfate ether, cationic surfactants such as stearyl trimethyl ammonium chloride, benzalkonium chloride, and lauryl amine oxide, imidazoline-based amphoteric surfactants (2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy 2 sodium salt, etc.), betaine-based surfactants (alkyl betaine, amide betaine, sulfobetaine, etc.), amphoteric surfactants such as acylmethyl taurine, sorbitan fatty acid esters (sorbitan monostearate, sorbitan sesquioleate, etc.), glycerin fatty acids (glycerin monostearate, etc.), propylene glycol fatty acid esters (propylene glycol monostearate, etc.), hydrogenated castor oil derivatives, glycerin alkyl ethers, POE sorbitan fatty acid esters (POE sorbitan monooleate, polyoxyethylene sorbitan monostearate, etc.), POE sorbit fatty acid esters (POE-sorbit monolaurate, etc.), POE glycerin fatty acid esters (POE-glycerin monoisostearate, etc.), POE fatty acid esters (polyethylene glycol monooleate, POE distearate, etc.), POE alkyl ethers (POE 2-octyldodecyl ether, etc.), POE alkyl phenyl ethers (POE nonyl phenyl ether, etc.), pluronic (registered trademark) types, POE·POP alkyl ethers (POE·POP 2-decyltetradecyl ether, etc.), tetronic types, POE castor oil·hydrogenated castor oil derivatives (POE castor oil, POE hydrogenated castor oil, etc.), sucrose fatty acid esters, nonionic surfactants such as alkyl glucoside, humectants such as sodium pyrrolidone carboxylate, lactic acid, and sodium lactate, powders such as mica, talc, kaolin, synthetic mica, calcium carbonate, magnesium carbonate, anhydrous silicic acid (silica), and barium sulfate, which may be surface-treated, inorganic pigments such as ultramarine and navy blue, which may be surface-treated,Composite pigments such as iron oxide titanium dioxide sintered bodies, which may be surface-treated, pearl agents such as mica titanium, fish scale foil, bismuth oxychloride, etc., Red No. 202, Red No. 228, Red No. 226, Yellow No. 4, Blue No. 404, Yellow No. 5, Red No. 505, Red No. 230, Red No. 223, Orange No. 201, Red No. 213, Yellow No. 204, Yellow No. 203, Blue No. 1, Green No. 201, Purple No. 201, Red No. 204, etc., which may be lake-colored, organic pigments, organic powders such as polyethylene powder, polymethyl methacrylate, nylon powder, organopolysiloxane elastomer, etc., lower alcohols such as ethanol, isopropanol, etc., vitamin A or its derivatives, vitamin B, 6 hydrochloride, vitamin B 6 tripalmitate, vitamin B 6 dioctanoate, vitamin B 2 or its derivatives, vitamin B 12 , vitamin B 15 or derivatives thereof, such as vitamin Bs, vitamin Es such as α-tocopherol, β-tocopherol, γ-tocopherol, vitamin E acetate, etc., vitamin Ds, vitamin H, pantothenic acid, pantethine, pyrroloquinoline quinone, etc., vitamins can be preferably exemplified.

[0052] (5) Method for producing sunscreen cosmetics The sunscreen cosmetics of the present invention can be produced by mixing and emulsifying an aqueous phase containing fine particle metal oxides, a hydrophilic film-forming polymer, and particles for forming a pickering emulsion, if necessary, with an oil phase.

[0053] In a preferred form of the present invention, it is preferable to mix fine particle metal oxides and a hydrophilic film-forming polymer in advance, prepare an aqueous dispersion of the fine particle metal oxides, and use this as an aqueous phase component. That is, fine particle metal oxides are mixed with a hydrophilic film-forming polymer and an aqueous medium such as water to prepare an aqueous dispersion (aqueous dispersion paste). Then, the aqueous dispersion is mixed with other aqueous phase components.

[0054] Thus, a sunscreen cosmetic produced through a process of preparing an aqueous dispersion containing fine particle metal oxide and film-forming polymer in advance forms, as a film formed after drying upon application, a film in which the film-forming polymer is oriented on the film surface, and the film is excellent in resistance to more physical rubbing.

[0055] The content of the fine particle metal oxide with respect to the total amount of the aqueous dispersion is preferably 10 to 50% by mass. The content of the film-forming polymer with respect to the total amount of the aqueous dispersion is preferably 10 to 50% by mass.

[0056] The content of the aqueous dispersion with respect to the total amount of the sunscreen cosmetic is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.5% by mass, particularly preferably 0.8% by mass or more, and most preferably 1% by mass or more. Also, the content of the aqueous dispersion with respect to the total amount of the sunscreen cosmetic is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 5% by mass or less, particularly preferably 2% by mass or less, and most preferably 1.5% by mass or less.

[0057] To aid in the understanding of the present invention, the film formation mechanism of a sunscreen cosmetic containing titanium oxide as (A), polyacrylic acid as (B), and silylated silica as (C) will be described with reference to FIG. 1. In the sunscreen cosmetic formulation or immediately after application, polyacrylic acid, which is a hydrophilic film-forming polymer, is oriented on titanium oxide, which is a fine particle metal oxide that is also hydrophilic. After the sunscreen cosmetic is applied to the skin and the film dries, the fine particle metal oxide and silylated silica, which are particles for forming a pickering emulsion, are oriented toward the skin side, and polyacrylic acid is oriented toward the interface side with air. Thus, by forming a dry film in which the hydrophilic film-forming polymer is oriented on the dry film surface, a film that is more resistant to physical rubbing can be formed.

Examples

[0058] <Test Example 1> Preparation of Sunscreen Cosmetics According to the formulations shown in Table 1, sunscreen cosmetics in the form of a pickering emulsion (O / W type) for Examples 1 and Comparative Example 1 were prepared. Further, an O / W type sunscreen cosmetic emulsified with a surfactant containing polysorbate 60 instead of silylated silica was prepared (Comparative Example 2). As the "aqueous dispersion of fine particle titanium oxide", a paste-like dispersion containing fine particle titanium oxide and sodium polyacrylate was used.

[0059]

Table 1

[0060] <Test Example 2> Evaluation Test for Resistance to Rubbing The prepared sunscreen cosmetic was applied to a PMMA plate HD6 for SPF analyzer measurement simulating skin so as to be 2 mg / cm 2 and dried for 15 minutes. Thereafter, a pressure of 300 g was applied to the applied sunscreen cosmetic, and it was rubbed 3 times with a cloth. Before rubbing and each time after rubbing once, the SPF was measured using an SPF analyzer, and with the SPF value before rubbing taken as 100%, the maintenance rate of the SPF value after rubbing was determined. This was repeated 3 times for each formulation, and the average value of the maintenance rate was calculated. The results are shown in Figure 2.

[0061] As shown in Figure 2, the sunscreen cosmetic of Example 1, which is a pickering emulsion containing fine particle metal oxide and a hydrophilic film-forming polymer, was superior in the SPF maintenance rate after rubbing compared to the sunscreen cosmetics of Comparative Example 1 and Comparative Example 2 through the first, second, and third times of rubbing.

[0062] From the comparison between Example 1 and Comparative Example 1, it was found that even for a pickering emulsion, a pickering emulsion containing fine particle metal oxide and a hydrophilic film-forming polymer (aqueous dispersion of fine particle metal oxide) is more excellent in resistance to rubbing.

[0063] Further, from the comparison with Example 1 and Comparative Example 2, it was found that Example 1, which is a pickering emulsion, is superior in resistance to rubbing compared to Comparative Example 2, which is a sunscreen cosmetic containing fine particle metal oxide and a hydrophilic film-forming polymer and emulsified with a surfactant.

[0064] From the above results, it was found that a sunscreen cosmetic containing fine particle metal oxide and a hydrophilic film-forming polymer and being a pickering emulsion is excellent in resistance to physical rubbing.

Industrial Applicability

[0065] The present invention can be applied to a formulation excellent in resistance to physical rubbing.

Claims

1. (A) Fine particle titanium oxide, (B) A hydrophilic film-forming polymer, and (C) silica-based fine particles, wherein the film-forming polymer is an acrylic polymer having a molecular weight of 2,000 to 20,000, the content of the film-forming polymer is 0.001 to 20% by mass based on the total amount of the sunscreen cosmetic, and it is a pickering emulsion, A sunscreen cosmetic.

2. The sunscreen cosmetic according to claim 1, wherein the content of the fine particle titanium oxide is 0.01 to 20% by mass based on the total amount of the sunscreen cosmetic.

3. The sunscreen cosmetic according to claim 1 or 2, wherein (C) is silylated silica.

4. The sunscreen cosmetic according to any one of claims 1 to 3, which substantially does not contain a surfactant.

5. The sunscreen cosmetic according to any one of claims 1 to 4, which is of the O / W type.

6. It is formulated with an aqueous dispersion obtained by premixing (A) and (B), The sunscreen cosmetic according to any one of claims 1 to 5, wherein the content of the film-forming polymer based on the total amount of the aqueous dispersion is 10 to 50% by mass.

7. It is formulated with an aqueous dispersion obtained by premixing (A) and (B), the content of the film-forming polymer based on the total amount of the aqueous dispersion is 10 to 50% by mass, and the content of the fine particle titanium oxide based on the total amount of the aqueous dispersion is 10 to 50% by mass. The sunscreen cosmetic according to any one of claims 1 to 5.

8. It is formulated with an aqueous dispersion obtained by premixing (A) and (B), The sunscreen cosmetic according to any one of claims 1 to 5, wherein the content of the aqueous dispersion based on the total amount of the sunscreen cosmetic is 0.1% by mass or more and 10% by mass or less.

9. A step of preparing an aqueous dispersion of fine particle metal oxide containing (A) fine particle titanium oxide and (B) a hydrophilic film-forming polymer, A step of mixing the aqueous phase containing the aqueous dispersion and an oil phase to prepare a pickering emulsion, the pickering emulsion contains (C) silica-based fine particles, the film-forming polymer is an acrylic polymer having a molecular weight of 2,000 to 20,000, the content of the film-forming polymer is 0.001 to 20% by mass based on the total amount of the sunscreen cosmetic, A method for producing a sunscreen cosmetic.

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