JP7691041B2 - Sunscreen cosmetics - Google Patents

Description

The present invention relates to a sunscreen cosmetic.

Compositions for external use that contain metal oxide powders are widely known. For example, fine particles of metal oxides such as titanium oxide, zinc oxide, zirconium oxide, and cerium oxide have the function of scattering, absorbing, and reflecting ultraviolet rays, and are therefore incorporated as ultraviolet shielding materials in compositions for external use such as sunscreens (for example, Patent Document 1).
Also known is a Pickering emulsion which is stabilized by adsorbing a metal oxide such as silica to the emulsion interface (for example, Patent Document 2).

The inventors have disclosed research results showing that a characteristic of formulations using Pickering emulsions is that when they come into contact with sweat (ions), the interfacial membrane of the powder aggregates, absorbing UV rays more efficiently and increasing the SPF (Non-Patent Document 1).

JP 2017-014300 A Special table 2017-503643 publication

Abstracts of the IFSCC 2016 Orlando Conference and International Reporting Session "Development of ion-responsive sunscreen formulations using Pickering emulsions"

Meanwhile, one of the physical properties required for a sunscreen cosmetic is resistance to physical friction.
Therefore, an object of the present invention is to provide a sunscreen cosmetic composition that is resistant to physical abrasion.

The inventors of the present invention have conducted intensive research based on the knowledge that one of the characteristics of Pickering emulsion preparations is that they form a film that is resistant to physical abrasion. As a result, they have discovered that a Pickering emulsion containing fine metal oxide particles and a hydrophilic film-forming polymer is more resistant to physical abrasion, and have completed the present invention.

That is, the present invention which solves the above problems is:
(A) a fine particle metal oxide;
(B) a hydrophilic film-forming polymer,
It is a Pickering emulsion.
It is a sunscreen cosmetic.
The sunscreen cosmetic composition of the present invention has excellent resistance to rubbing.

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

In a preferred embodiment of the present invention, the film-forming polymer is an acrylic polymer.

In a preferred embodiment of the present invention, the fine particle metal oxide is fine particle titanium oxide.

In a preferred embodiment of the present invention, the composition further contains (C) silica-based fine particles.

In a preferred embodiment of the present invention, (C) is silica silylate.

In a preferred embodiment of the present invention, the sunscreen cosmetic is substantially free of surfactants.

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

In a preferred embodiment of the present invention, the sunscreen cosmetic is formulated with an aqueous dispersion of fine metal oxide particles in which (A) and (B) are premixed.

Further, the present invention which solves the above-mentioned problems is as follows:
(A) a fine particle metal oxide;
(B) preparing an aqueous dispersion of a particulate metal oxide comprising a hydrophilic film-forming polymer;
and mixing an aqueous phase containing the aqueous dispersion with an oil phase to prepare a Pickering emulsion.
A method for producing a sunscreen cosmetic.

The sunscreen cosmetic of the present invention has excellent physical resistance to rubbing.

FIG. 1 is a diagram showing a mechanism for forming a film resistant to physical abrasion. 1 is a graph showing the results of an evaluation test of resistance to rubbing.

The sunscreen cosmetic of the present invention contains as essential components (A) a finely divided metal oxide and (B) a hydrophilic film-forming polymer.
Each component will be described in detail below.

(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 size in the range of 10 to 100 nm as determined by observation with an electron microscope.
The average primary particle size of the fine particle metal oxide is preferably 5 to 80 nm, and more preferably 5 to 50 nm.

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

Fine particle metal oxides can be produced by standard methods such as thermally decomposing metal salts in the gas phase, but many commercially available products can also be used.

The content of the fine particle metal oxide is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, even more preferably 0.1 to 8% by mass, and particularly preferably 0.5 to 5% by mass, based on the total amount of the sunscreen cosmetic.

As will be described later, in the sunscreen cosmetic of the present invention, the fine particle metal oxide (A) does not necessarily have to be particles that are adsorbed to the interface between the aqueous phase and the oil phase to form a Pickering emulsion, and may also contain particles that are used to form a Pickering emulsion separately.
On the other hand, the fine particle metal oxide of (A) may contribute to the formation of a Pickering emulsion.

(2) (B) Hydrophilic Film-Forming Polymer In this specification, the term "hydrophilic" means the property of being soluble or dispersible in water.
Moreover, the term "film-forming polymer" refers to a polymer that has film-forming properties when dried.

The type of hydrophilic film-forming polymer is not particularly limited, and examples include vinyl polymers such as polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, polyvinylpyrrolidone, and vinyl acetate-vinylpyrrolidone copolymers, and acrylic polymers such as polyacrylic acid, sodium polyacrylate, and alkyl acrylate copolymers.
Of these, acrylic polymers are preferred, and polyacrylic acid or a salt thereof is more preferred.

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

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

(3) Formulation The sunscreen cosmetic of the present invention is in the form of a Pickering emulsion.
A Pickering emulsion is an emulsion composition stabilized by particles. If the particles contribute to emulsion stability, the emulsion composition is called a Pickering emulsion even if it contains other surfactants. However, it is preferable that the sunscreen cosmetic of the present invention does not substantially contain any surfactants.
The content of the surfactant is preferably 1 mass % or less, more preferably 0.5 mass % or less, even more preferably 0.1 mass % or less, particularly preferably 0.01 mass % or less, based on the total amount of the sunscreen cosmetic, and most preferably none is contained.

Pickering emulsion preparations have better resistance to physical abrasion than emulsion preparations that use surfactants.

The particles that contribute to the emulsion stability of the Pickering emulsion may be the fine particle metal oxide (A) or other particles.
As the other particles, (C) silica-based fine particles are preferred.

When silica-based fine particles are used, either so-called dry silica particles produced by vapor phase oxidation of silicon halide, or so-called wet silica particles produced from water glass or the like may be used.
As the dry silica particles, for example, the Aerosil series (Nippon Aerosil Co., Ltd.), the CAB-O-SIL series (Cabot Corporation), and the HDK series (Wacker Asahi Kasei Silicone Co., Ltd.) can be used. As the wet silica powder, for example, the Nipsil series (Tosoh Silica Corporation), the 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 to add hydrophobic groups to hydroxyl groups present on the surface of the powder through covalent bonds, or by physically attaching the hydrophobizing agent to the surface of the silica-based fine particles to cover them.

The hydrophobic treatment may be carried out by treating the metal oxide powder with a hydrophobic treatment agent such as an organosilicon compound, silicone, hydrocarbon oil, fatty acid, fatty acid amide, fatty acid ester, higher alcohol, or polyoxyalkylene compound.
It is particularly preferable to treat the metal oxide particles with an organosilicon compound or silicone as a hydrophobic treatment agent.

Organosilicon compounds include hexamethyldisilazane, monomethylsilane, dimethylsilane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, palmitylsilane, etc. These may be used alone or in a mixture of two or more.

Examples of silica-based fine particles include hydrophobic silica fine particles having hydrophobic groups added to the surface thereof, such as alkylsilyl groups, such as monomethylsilyl groups, dimethylsilyl groups, trimethylsilyl groups, and octylsilyl groups, alkylsiloxane groups, such as dimethylsiloxane groups, alkylpolysiloxane groups, such as dimethylpolysiloxane groups, aminoalkylsilyl groups, and methacrylsilyl groups.
Among these, silylated silica having an alkylsilyl group added to the surface is preferred, and silylated silica having a trimethylsilyl group added is more preferred.

The emulsion 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 composition of the present invention is preferably an O/W type.

(4) Sunscreen Cosmetic The sunscreen cosmetic of the present invention is, as described above, a Pickering emulsion containing (A) 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, wax, hydrocarbon oils, higher fatty acids, higher alcohols, ester oils, silicone oils, and the like.

Examples of liquid oils 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, sasanqua oil, castor oil, linseed oil, safflower oil, cottonseed oil, perilla oil, meadowfoam oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, Chinese tung oil, Japanese tung oil, jojoba oil, germ oil, triglycerin, glycerin trioctanoate, glycerin triisopalmitate, etc.

Examples of solid fats and oils include cacao butter, coconut oil, horse tallow, hardened coconut oil, palm oil, beef tallow, mutton tallow, hardened beef tallow, palm kernel oil, lard, beef bone fat, Japan Rice Kernel Oil, hardened oil, beef foot fat, Japan Rice, and hardened castor oil.

Examples of waxes include beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, ivory wax, whale wax, montan wax, bran wax, lanolin, kapok wax, lanolin acetate, liquid lanolin, sugarcane wax, lanolin fatty acid isopropyl, hexyl laurate, reduced lanolin, jojoba wax, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, and POE hydrogenated lanolin alcohol ether.

Hydrocarbon oils include liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, etc.

Examples of higher fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, undecylenic acid, tallic acid, etc.

Examples of higher alcohols include cetyl alcohol, stearyl alcohol, behenyl alcohol, batyl alcohol, myristyl alcohol, and cetostearyl alcohol.

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-ethylhexylate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glycerin di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexylate, trimethylolpropane triisostearate, pentane tetra-2-ethylhexylate, Lithritol, glycerin tri-2-ethylhexyl acid, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, glycerin trimyristate, tri-2-heptylundecanoic acid glyceride, castor oil fatty acid methyl ester, oleic acid oil, cetostearyl alcohol, acetoglyceride, 2-heptylundecyl palmitate, cetyl palmitate, adipose Examples include diisobutyl phosphate, N-lauroyl-L-glutamic acid-2-octyldodecyl ester, 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, and triethyl citrate.

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

The oil phase can use one or more of the oils listed above.

The aqueous phase in the Pickering emulsion of the present invention may contain any component typically used in cosmetics without any particular limitation, but it is preferable that it contains, for example, the following components:
Examples of polyols 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, and 1,2-octanediol. Of these, glycerin, 1,3-butylene glycol, and sorbitol are preferred.

Thickeners may also be included. Examples of thickeners 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, mucoitin sulfate, hydroxyethyl guar gum, carboxymethyl guar gum, dextran, keratosulfuric acid, locust bean gum, succinoglucan, caronic acid, chitin, chitosan, carboxymethyl chitin, agar, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, sodium polyacrylate, polyethylene glycol, sodium acrylate grafted starch, stearoxy hydroxypropyl methylcellulose, and bentonite.

The sunscreen cosmetic composition of the present invention may contain an ultraviolet absorbing agent.
Examples of ultraviolet absorbents include benzoic acid derivatives such as paraaminobenzoic acid, paraaminobenzoic acid monoglycerin ester, N,N-dipropoxy paraaminobenzoic acid ethyl ester, N,N-diethoxy paraaminobenzoic acid ethyl ester, N,N-dimethyl paraaminobenzoic acid ethyl ester, N,N-dimethyl paraaminobenzoic acid butyl ester, N,N-dimethyl paraaminobenzoic acid ethyl ester, and diethylaminohydroxybenzoyl hexyl benzoate; anthranilic acid derivatives such as homomenthyl-N-acetylanthranilate; salicylic acid and its sodium salt, salicylic acid derivatives such as amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, and p-isopropanol phenyl salicylate; octyl cinnamate, ethyl-4-isopropyl cinnamate, methyl-2,5-diisopropyl Pilcinnamate, ethyl 2,4-diisopropylcinnamate, methyl 2,4-diisopropylcinnamate, propyl p-methoxycinnamate, isopropyl p-methoxycinnamate, isoamyl p-methoxycinnamate, 2-ethylhexyl p-methoxycinnamate (ethylhexyl methoxycinnamate, octyl p-methoxycinnamate), 2-ethoxyethyl p-methoxycinnamate (cinoxate), cyclo cinnamic acid derivatives such as hexyl-p-methoxycinnamate, ethyl-α-cyano-β-phenylcinnamate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate (octocrylene), glyceryl mono-2-ethylhexanoyl-di-para-methoxycinnamate, ferulic acid and its derivatives; 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-di Benzophenone derivatives such as methoxybenzophenone, 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, and 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'-methylphenyl)benzotriazole;dibenzoylmethane;5-(3,3-dimethyl-2-norbornylidene)-3-pentan-2-one; dibenzoylmethane derivatives such as 4-t-butylmethoxydibenzoylmethane; octyl triazone; 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, and 2-ethylhexyl dimethoxybenzylidene dioxoimidazolidinepropionate; phenylbenzimidazol sulfonic acid, terephthalidene dicamphor sulfonic acid, drometrizole trisiloxane, methyl anthranilate, bisethylhexyloxyphenol methoxyphenyl triazine, rutin and derivatives thereof, and oryzanol and derivatives thereof are preferred.

In addition to the above-mentioned components, the sunscreen cosmetic of the present invention may contain optional components that are generally used in cosmetics, provided that the effects of the present invention are not impaired. Examples of such optional components include anionic surfactants such as fatty acid soaps (sodium laurate, sodium palmitate, etc.), potassium lauryl sulfate, and alkyl triethanolamine ether sulfate, cationic surfactants such as stearyltrimethylammonium chloride, benzalkonium chloride, and laurylamine oxide, imidazoline-based amphoteric surfactants (2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, etc.), betaine-based surfactants (alkyl betaines, amido betaines, sulfobetaines, etc.), and amphoteric surfactants such as acyl methyl taurine, sorbitan fatty acid esters (sorbitan monostearate, sesquioleate, etc.), and the like. sorbitan phosphate, 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 sorbitan fatty acid esters (POE-sorbitan 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 ter, etc.), POE alkyl phenyl ethers (POE nonylphenyl ether, etc.), Pluronic (registered trademark) types, POE/POP alkyl ethers (POE/POP 2-decyltetradecyl ether, etc.), Tetronics, POE castor oil/hydrogenated castor oil derivatives (POE castor oil, POE hydrogenated castor oil, etc.), sucrose fatty acid esters, nonionic surfactants such as alkyl glucosides, moisturizing ingredients such as sodium pyrrolidone carboxylate, lactic acid, sodium lactate, etc., powders such as mica, talc, kaolin, synthetic mica, calcium carbonate, magnesium carbonate, silicic anhydride (silica), barium sulfate, etc., which may be surface-treated, inorganic substances such as ultramarine and Prussian blue, etc. Pigments, composite pigments such as sintered iron oxide titanium dioxide which may be surface-treated, pearling agents such as titanium mica, fish phosphorus foil, bismuth oxychloride which may be surface-treated, organic dyes such as 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 which may be laked, organic powders such as polyethylene powder, polymethyl methacrylate, nylon powder, organopolysiloxane elastomer, lower alcohols such as ethanol, isopropanol, vitamin A or its derivatives, vitamin B Preferred examples of the vitamin B _group include vitamin _B6 hydrochloride, vitamin _B6 tripalmitate, vitamin _B6 dioctanoate, vitamin B2 or a derivative thereof, vitamin _B12 , vitamin _B15 or a derivative thereof, etc.; vitamin E group including α-tocopherol, β-tocopherol, γ-tocopherol, vitamin E acetate, etc.; vitamin D group, vitamin H, pantothenic acid, pantethine, pyrroloquinoline quinone, etc.

(5) Method for Producing Sunscreen Cosmetic The sunscreen cosmetic of the present invention can be produced by mixing and emulsifying an aqueous phase containing fine particle metal oxide, a hydrophilic film-forming polymer, and, if necessary, particles for forming a Pickering emulsion, with an oil phase.

In a preferred embodiment of the present invention, it is preferred that a fine particle metal oxide is mixed with a hydrophilic film-forming polymer in advance to prepare an aqueous dispersion of the fine particle metal oxide, and this dispersion is used as the aqueous phase component.
That is, a fine particle metal oxide is mixed with a hydrophilic film-forming polymer and an aqueous medium such as water to prepare an aqueous dispersion (aqueous dispersion paste), which is then mixed with other aqueous phase components.

In this way, the sunscreen cosmetic produced by the process of preparing an aqueous dispersion containing fine metal oxide particles and a film-forming polymer in advance forms a film on the surface of the coating that is dried after application, in which the film-forming polymer is oriented, and the film has excellent resistance to physical abrasion.

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

The content of the aqueous dispersion relative to the total amount of the sunscreen cosmetic is preferably 0.1 mass % or more, more preferably 0.3 mass % or more, even more preferably 0.5 mass % or more, particularly preferably 0.8 mass % or more, and most preferably 1 mass % or more.
The content of the aqueous dispersion relative to the total amount of the sunscreen cosmetic is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, particularly preferably 2% by mass or less, and most preferably 1.5% by mass or less.

To aid in understanding the present invention, the film-forming mechanism of a sunscreen cosmetic composition containing titanium oxide as (A), polyacrylic acid as (B), and silica silylate as (C) will be explained with reference to FIG. 1.
In the sunscreen cosmetic preparation or immediately after application, polyacrylic acid, which is a hydrophilic film-forming polymer, orients to titanium oxide, which is a fine particle metal oxide, which is also hydrophilic.
When the sunscreen cosmetic is applied to the skin and the film dries, the fine metal oxide particles and the silica silylate particles used to form Pickering emulsions are oriented toward the skin, and the polyacrylic acid is oriented toward the interface with the air.
In this way, a dry film is formed in which the hydrophilic film-forming polymer is oriented on the surface of the dry film, and thus a film that is more resistant to physical abrasion can be formed.

Test Example 1: Preparation of Sunscreen Cosmetics Pickering emulsions (O/W type) of sunscreen cosmetics of Example 1 and Comparative Example 1 were prepared according to the formulations shown in Table 1. In addition, an O/W type sunscreen cosmetic emulsified with a surfactant containing polysorbate 60 instead of silica silylate was prepared (Comparative Example 2).
As the "aqueous dispersion of fine titanium dioxide particles", a paste-like dispersion containing fine titanium dioxide particles and sodium polyacrylate was used.

<Test Example 2> Evaluation test of resistance to rubbing The prepared sunscreen cosmetic was applied to a PMMA plate HD6 for SPF analyzer measurement simulating skin to a thickness of 2 mg/ ^cm2 , and dried for 15 minutes. Then, a pressure of 300 g was applied to the applied sunscreen cosmetic, and the cosmetic was rubbed three times with a cloth. The SPF was measured using an SPF analyzer before rubbing and after each rub, and the SPF value retention rate after rubbing was calculated, with the SPF value before rubbing being set at 100%. This was repeated three times for each formulation, and the average retention rate was calculated.
The results are shown in Figure 2.

As shown in Figure 2, the sunscreen cosmetic of Example 1, which is a Pickering emulsion containing fine metal oxide particles and a hydrophilic film-forming polymer, had a superior SPF retention rate after rubbing compared to the sunscreen cosmetics of Comparative Examples 1 and 2 throughout the first, second, and third rubbing cycles.

Compared with Example 1 and Comparative Example 1, it was found that Pickering emulsions, which contain fine metal oxide particles and a hydrophilic film-forming polymer (aqueous dispersion of fine metal oxide particles), have better resistance to abrasion.

In addition, a comparison between Example 1 and Comparative Example 2 revealed that Example 1, which is a Pickering emulsion, contains fine metal oxide particles and a hydrophilic film-forming polymer, and has superior resistance to rubbing compared to Comparative Example 2, which is a sunscreen cosmetic emulsified with a surfactant.

These results show that sunscreen cosmetics that contain fine metal oxide particles and a hydrophilic film-forming polymer and are Pickering emulsions have excellent resistance to physical abrasion.

The present invention can be applied to preparations that have excellent resistance to physical abrasion.

Claims (9)

(A) fine particle titanium dioxide ;
(B) a hydrophilic film-forming polymer; and
(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;
It is a Pickering emulsion.
Sunscreen cosmetics. 2. The sunscreen cosmetic according to claim 1, wherein the content of said fine particle titanium dioxide is 0.01 to 20% by mass based on the total amount of the sunscreen cosmetic. 3. The sunscreen cosmetic according to claim 1 , wherein the (C) is silica silylate. The sunscreen cosmetic composition according to any one of claims 1 to 3 , which is substantially free of a surfactant. The sunscreen cosmetic composition according to any one of claims 1 to 4 , which is an O/W type. The composition is prepared by blending an aqueous dispersion in which the (A) and the (B) are mixed in advance,
6. The sunscreen cosmetic according to claim 1, wherein the content of the film-forming polymer is 10 to 50% by mass based on the total amount of the aqueous dispersion. The composition is prepared by blending an aqueous dispersion in which the (A) and the (B) are mixed in advance,
the content of the film-forming polymer relative to the total amount of the aqueous dispersion is 10 to 50% by mass,
6. The sunscreen cosmetic according to claim 1, wherein the content of said fine particle titanium dioxide is 10 to 50 mass % based on the total amount of said aqueous dispersion. The composition is prepared by blending an aqueous dispersion in which the (A) and the (B) are mixed in advance,
6. The sunscreen cosmetic according to claim 1, wherein the content of said aqueous dispersion is from 0.1% by mass to 10% by mass based on the total amount of the sunscreen cosmetic. A method for producing a particulate metal oxide aqueous dispersion comprising: (A) particulate titanium dioxide ; and (B) a hydrophilic film-forming polymer;
and mixing an aqueous phase containing the aqueous dispersion with 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.