Pickering emulsion with visible light transparency

Abstract

To provide a Pickering emulsion excellent in a cool feeling of appearance and water resistance.SOLUTION: A visible light-translucent Pickering emulsion contains an aqueous phase containing polyol and / or thickener, an oil phase, and powder.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to Pickering emulsions that are visible light transparent. [Background technology]

[0002] Formulations in which amphiphilic solid particles are adsorbed to the interface to form an emulsion have been known as Pickering emulsions, and their use in cosmetics has also been proposed. For example, titanium dioxide, zinc oxide, etc. have been proposed as the solid particles, and it has been proposed to use these solid particles with hydrophobic surfaces in the preparation of Pickering emulsions (Patent Document 1). In addition, oil-in-water emulsions using partially hydrophobized silica have also been proposed, and are considered to have good high-temperature emulsion stability (Patent Document 2).

[0003] Since Pickering emulsions have an oil phase, a water phase, and powder, they generally have a cloudy appearance due to light scattering at the interfaces between these components, and therefore lack a refreshing feeling in appearance and may leave a white cast on the skin after application.

[0004] Incidentally, since the external phase of a water-in-oil emulsion cosmetic is an oil agent, it is easy to impart water resistance, and this formulation is often used for sunscreens, etc. For example, Patent Document 3 discloses a water-in-oil emulsion cosmetic for sunscreen use that contains an ultraviolet absorber, and describes that this cosmetic has excellent water resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2001-518111 [Patent Document 2] JP 2013-129626 A [Patent Document 3] JP 2011-126832 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a Pickering emulsion that has a refreshing feel in appearance and excellent sweat resistance.

[0007] As described above, the water-resistant effect of conventional water-in-oil emulsion cosmetics is due to the property that the oil that constitutes the external phase has no affinity for water. However, the present inventors have discovered that when such water-in-oil emulsion cosmetics come into contact with an aqueous solution containing ions, such as seawater or sweat, the hydrophilic groups of the oil that constitutes the external phase react with the ions to form hydrophilic salts, causing the oil to dissolve. In other words, although conventional water-in-oil emulsion cosmetics claim to have water-resistant properties, they are inferior in resistance to sweat and seawater, making them uneffective.

[0008] In view of the above problems, an object of a preferred embodiment of the present invention is to provide a Pickering emulsion that is resistant to aqueous solutions containing ions, such as seawater and sweat. [Means for solving the problem]

[0009] As a result of intensive research and efforts, the present inventors have made the surprising discovery that a Pickering emulsion endowed with visible light transmittance in order to improve the visual cool feeling is also excellent in sweat resistance at the same time, and have thus completed the present invention. The present invention, which solves the above-mentioned problems, provides a Pickering emulsion having visible light transparency, which comprises an aqueous phase containing a polyol and / or a thickener, an oil phase, and a powder. The Pickering emulsion of the present invention has visible light transmittance, and therefore has an excellent refreshing feel when viewed, and also has excellent sweat resistance.

[0010] In a preferred embodiment of the present invention, the powder has a relative refractive index of 0.7 to 1.3 with respect to the oil phase. By using a powder whose relative refractive index to the oil phase is in the above range, the apparent cool feeling and sweat resistance of the Pickering emulsion can be improved.

[0011] In a preferred embodiment of the present invention, the relative refractive index of the aqueous phase to the oil phase is 0.8 to 1.2. By setting the relative refractive index of the water phase to that of the oil phase within the above range, the Pickering emulsion can have an improved refreshing appearance and sweat resistance.

[0012] In a preferred embodiment of the present invention, the aqueous phase contains 30% by mass or more of a polyol. The Pickering emulsion of the present invention containing a polyol within the above range has better transparency and sweat resistance.

[0013] In a preferred embodiment of the present invention, the aqueous phase contains 0.1% by mass or more of a thickener. The Pickering emulsion of the present invention containing a thickener in the above range has better transparency and sweat resistance.

[0014] In a preferred embodiment of the present invention, the viscosity at 25° C. and 1 atmospheric pressure is 4000 mPa·s or more. The Pickering emulsion of the present invention having such a viscosity has excellent stability.

[0015] In a preferred embodiment of the present invention, the powder is a partially hydrophobized powder in which a part of the surface is coated with a hydrophobizing agent. By using a partially hydrophobic powder, it is possible to provide a Pickering emulsion having excellent sweat resistance and stability. Effect of the Invention

[0016] The Pickering emulsion of the present invention has excellent cool feeling and sweat resistance, and in a preferred embodiment, has excellent moisturizing properties. Furthermore, the Pickering emulsion of the present invention has excellent resistance to aqueous solutions containing ions. [Brief description of the drawings]

[0017] [Figure 1] 1 is a bar graph showing the zeta potential of partially hydrophobized silica when dispersed in pure water and seawater. [Diagram 2] 1 is a bar graph showing the amount of ethylhexyl methoxycinnamate dissolved into seawater from the coating films of the emulsions of Reference Example 1 and Comparative Example 4. [Diagram 3] Electron microscope photographs showing the cross sections of the coating films of the emulsions of Reference Example 1 and Comparative Example 4 before and after immersion in seawater. [Figure 4] 1 is a bar graph showing the SPF values ​​of coating films of the emulsions of Reference Example 1 and Comparative Example 4 after immersion in seawater, based on the SPF values ​​before immersion in seawater. [Diagram 5] 1 is a graph showing the scattering rate of ultraviolet light of a coating film of the emulsion of Reference Example 1 before and after contact with seawater. [Figure 6] 1 is an electron microscope photograph of the Pickering emulsion of Reference Example 2. [Figure 7] Electron microscope photographs showing the cross sections of the coating films of the emulsions of Reference Example 1 and Comparative Example 5 after immersion in seawater. [Figure 8] Electron microscope photographs showing the cross section of the coating film of the Pickering emulsion of Reference Example 1 before and after immersion in pure water or seawater. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention relates to a Pickering emulsion which comprises an aqueous phase containing a polyol and / or a thickener, an oil phase, and a powder, and which has visible light transparency. The components, composition, etc. of the Pickering emulsion of the present invention will be described in detail below. In the present invention, a Pickering emulsion refers to an emulsion composition stabilized by using a powder. If the powder contributes to emulsion stability, the emulsion composition is called a Pickering emulsion even if it contains other surfactants.

[0019] The Pickering emulsion of the present invention has visible light transmittance. Here, "having visible light transmittance" means that the transmittance of visible light is not 0% when the optical path length is 1 cm. The visible light transmittance of the Pickering emulsion of the present invention is preferably 20% or more, more preferably 50% or more, even more preferably 70% or more, and still more preferably 80% or more, when the optical path length is 1 cm. The Pickering emulsion of the present invention, which contains a polyol and / or a thickener and has visible light transmittance, not only has an excellent refreshing feel to the eye, but also has excellent water resistance.

[0020] The aqueous phase is not particularly limited as long as it has visible light transparency. In a preferred embodiment of the present invention, the relative refractive index of the aqueous phase to the oil phase is preferably 0.8 to 1.2, more preferably 0.9 to 1.1, and even more preferably 0.95 to 1.05. It is particularly preferred that the refractive index of the aqueous phase is substantially the same as that of the oil phase. By setting the refractive index of the aqueous phase within the above range, it is possible to provide a Pickering emulsion that is highly transparent and has an excellent refreshing feel in appearance, and also to improve the sweat resistance of the Pickering emulsion. The relative refractive index of the aqueous phase to the oil phase refers to the value obtained by dividing the refractive index of the aqueous phase by the refractive index of the oil phase. The refractive index of the aqueous phase can be adjusted by adding various additives to the aqueous phase, but it is preferable to adjust it by adjusting the polyol content and / or the thickener content, or by adding a salt that ionizes in water, such as sodium chloride or magnesium sulfate.

[0021] In a preferred embodiment of the present invention, the content of the polyol in the aqueous phase is preferably 30% by mass or more, more preferably 30 to 90% by mass, even more preferably 40 to 80% by mass, and more preferably 50 to 70% by mass. By setting the polyol content within the above range, the transparency and sweat resistance of the Pickering emulsion can be improved.

[0022] The polyol content in the entire Pickering emulsion is preferably 5% by mass or more, more preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably 30 to 50% by mass. By setting the polyol content within the above range, the moisture retention of the Pickering emulsion can be improved.

[0023] 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 and 1,3-butylene glycol are preferred.

[0024] In a preferred embodiment of the present invention, the content of the thickener is preferably 0.1% by mass or more, more preferably 0.1 to 5% by mass, and even more preferably 0.3 to 2% by mass, based on the aqueous phase. By setting the content of the thickener within the above range, the transparency and sweat resistance of the Pickering emulsion can be improved.

[0025] The content of the thickener in the entire Pickering emulsion is preferably 0.05% by mass or more, more preferably 0.05 to 5% by mass, and even more preferably 0.1 to 1% by mass.

[0026] Thickening agents 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, Examples of suitable polysaccharides include keratosulfuric acid, locust bean gum, succinoglucan, caronic acid, chitin, chitosan, carboxymethylchitin, agar, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, sodium polyacrylate, polyethylene glycol, sodium acrylate grafted starch, stearoxy hydroxypropyl methylcellulose, and bentonite, and more preferably, water-soluble polysaccharides such as xanthan gum and guar gum, agar, sodium acrylate grafted starch, and stearoxy hydroxypropyl methylcellulose. More preferably, water-soluble polysaccharides such as xanthan gum and guar gum, and agar are preferred.

[0027] The oil constituting the oil phase in the Pickering emulsion of the present invention is not particularly limited as long as it has visible light transmittance, and may contain liquid oils and fats, solid oils and fats, wax, hydrocarbon oils, higher fatty acids, higher alcohols, ester oils, silicone oils, etc.

[0028] Examples of 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, 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 giri oil, Japanese tung oil, jojoba oil, germ oil, triglycerin, glycerin trioctanoate, and glycerin triisopalmitate.

[0029] 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.

[0030] 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.

[0031] Examples of the hydrocarbon oil include liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, and microcrystalline wax.

[0032] Examples of higher fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, undecylenic acid, and tall acid.

[0033] Examples of higher alcohols include cetyl alcohol, stearyl alcohol, behenyl alcohol, batyl alcohol, myristyl alcohol, and cetostearyl alcohol.

[0034] 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 of the ethyl acetate 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.

[0035] Examples of silicone oils include chain polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and diphenylsiloxyphenyltrimethicone, and cyclic polysiloxanes such as pentasiloxane, decamethylpolysiloxane, dodecamethylpolysiloxane, and tetramethyltetrahydrogenpolysiloxane.

[0036] Among them, silicone oil, ester oil, liquid oil, solid oil and wax are preferably used, and particularly, diphenylpolysiloxane, cetyl ethylhexanoate, etc. One or more kinds of oils can be used.

[0037] In the present invention, a powder can be used which can form a Pickering emulsion and has visible light transmittance when its surface is wetted with an oil phase component. Such powders preferably have the following refractive indexes. That is, it is preferable to use a powder whose relative refractive index to the oil phase is preferably 0.7 to 1.3, more preferably 0.8 to 1.2, and even more preferably 0.90 to 1.1. In particular, it is preferable to use a powder whose refractive index is substantially the same as that of the oil phase. By using such a powder, it is possible to provide a Pickering emulsion having high transparency and excellent refreshing feeling in appearance, and also to improve the sweat resistance of the Pickering emulsion. The relative refractive index of the powder with respect to the oil phase refers to the value obtained by dividing the refractive index of the powder by the refractive index of the oil phase.

[0038] Examples of such powders include inorganic powders (e.g., talc, kaolin, mica, sericite, white mica, gold mica, synthetic mica, red mica, black mica, vermiculite, magnesium carbonate, calcium carbonate, aluminum silicate, barium silicate, calcium silicate, magnesium silicate, strontium silicate, tungstate metal salts, magnesium, silica, zeolite, barium sulfate, calcined calcium sulfate (calcined gypsum), calcium phosphate, fluorapatite, hydroxyapatite, ceramic powder, etc.), metal soaps (e.g., zinc myristate, calcium palmitate, aluminum stearate), boron nitride, titanium dioxide, zinc oxide, iron oxide, etc.); organic polymer powders such as polyacrylic acid and its derivatives, polymethacrylic acid and its derivatives, silicone and its derivatives, polyethylene, polypropylene, polyvinyl acetate, vinyl chloride, nylon, polyester, polystyrene, polycarbonate, polyvinyl alcohol, polyoxyethylene, sucrose and its derivatives; pearl pigments (for example, titanium oxide coated mica, titanium oxide coated bismuth oxychloride, titanium oxide coated talc, colored titanium oxide coated mica, bismuth oxychloride, fish scale foil, etc.), and the like, which can be used alone or in combination of two or more types. Also usable are composite powders obtained by coating powder with metal oxide or the like, and powders whose surfaces have been treated with compounds or the like.

[0039] In the present invention, it is preferable to use hydrophobic powder whose surface is entirely or partially covered with a hydrophobic treatment agent. Here, "the surface of the powder is entirely or partially coated" refers not only to a state in which the surface of the powder is coated by physically adhering thereto a hydrophobic treatment agent, but also to a state in which hydrophobic groups derived from the hydrophobic treatment agent are covalently bonded to functional groups exposed on the surface of the powder. When silica or metal oxide is used as the powder, the hydrophobic powder can be prepared by reacting the powder with a hydrophobic treatment agent to add hydrophobic groups to hydroxyl groups present on the surface of the powder through covalent bonds, or by coating the surface of the powder by physically adhering the hydrophobic treatment agent.

[0040] When silica fine particles are used as the powder, either so-called dry silica powder produced by vapor phase oxidation of silicon halide, or so-called wet silica powder produced from water glass or the like may be used. As the dry silica powder, for example, the Aerosil series (Nippon Aerosil Co., Ltd.), CAB-O-SIL series (Cabot Corporation), and HDK series (Wacker Asahi Kasei Silicone Co., Ltd.) can be used. As the wet silica powder, for example, the Nipsil series (Tosoh Silica Corporation), HI-SIL series (PPG), and other commercially available products can be used.

[0041] The hydrophobic treatment may be carried out by treating the 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 powder with an organosilicon compound or silicone as a hydrophobic treatment agent.

[0042] Examples of the organosilicon compound include hexamethyldisilazane, monomethylsilane, dimethylsilane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, palmitylsilane, etc. These may be used alone or in combination of two or more. In a preferred embodiment of the present invention, a hydrophobized powder is used in which a powder is treated with trimethylsilane and trimethylsilyl groups are added to the surface, and it is particularly preferred to use partially hydrophobized silica in which silica fine particles are treated with trimethylsilane and trimethylsilyl groups are partially added to the surface.

[0043] Examples of silicones include dimethyl silicone, methylphenyl silicone, α-methylstyrene modified silicone, chlorophenyl silicone, and fluorine modified silicone.

[0044] When the Pickering emulsion is an oil-in-water type, the M value of the hydrophobized powder can be 0-9, more preferably 0-5, even more preferably 0-3, even more preferably 0-2, and even more preferably 0-1.

[0045] When the Pickering emulsion is a water-in-oil type, the lower limit of the M value of the hydrophobized powder can be preferably 0 or more, more preferably 2 or more, even more preferably 5 or more, and even more preferably 15 or more. When the Pickering emulsion is a water-in-oil type, the upper limit of the M value of the hydrophobized powder can be preferably 100 or less, more preferably 80 or less, and further preferably 60 or less.

[0046] The M value indicates the degree of hydrophobicity of the particles, and the higher the M value, the higher the hydrophobicity. The M value is expressed as the volume ratio of the minimum amount of methanol required to uniformly disperse the measurement sample in a mixed solution of water and methanol, and can be calculated using the following method.

[0047] [M value calculation method] 0.2 g of the measurement sample (hydrophobic powder particles) is added to 50 mL of water in a 250 mL beaker, and then methanol is slowly added dropwise from a burette. The solution in the beaker is constantly stirred with a magnetic stirrer, and the end point is when the entire amount of the measurement sample is uniformly suspended in the solution. The volume percentage of methanol in the water-methanol mixture in the beaker at this end point is the M value. The M value of the hydrophobized powder can be adjusted by its hydrophobization rate. The M value or hydrophobization rate can be adjusted by appropriately setting the mixing ratio of the powder and the hydrophobizing agent and the treatment time.

[0048] It is preferable to use a hydrophobized powder having a charged surface. The surface charge of the hydrophobized powder may be positive or negative, but is preferably negative. In this case, the hydrophobized powder only needs to be charged at least in an emulsified state, that is, in a state in contact with water, and does not need to have a charge before the emulsion is prepared.

[0049] Preferred examples of the hydrophobic powder having a charged surface include silica, and hydrophobic metal oxides such as titanium oxide, zinc oxide, and iron oxide, and particularly preferably partially hydrophobic metal oxides. Silica powder is negatively charged in water, and metal oxides are positively and negatively charged in water.

[0050] The average primary particle size of the powder can be approximately 1 to 1000 nm, preferably 3 to 100 nm, and more preferably 5 to 30 nm.

[0051] The average secondary particle size of the powder can be preferably set as a guide of 1 μm or less, preferably 500 nm or less, more preferably 200 nm or less, and even more preferably 50 nm or less. By setting the average secondary particle size within the above range, the emulsified particle size can be made smaller, the degree of aggregation of the coating film after contact with an aqueous solution containing ions can be improved, and the resistance to the aqueous solution can be further increased.

[0052] Furthermore, by setting the average secondary particle size within the above range, the emulsion particle size can be made smaller, and the emulsion stability can be improved.

[0053] Here, the average primary particle size and the average secondary particle size can be determined by measuring the maximum diameters of 2500 or more particles on a scanning electron microscope image and calculating the number average. The average secondary particle size can be adjusted by the stress applied to the composition during emulsification.

[0054] In a preferred embodiment of the present invention, the powder content can be preferably 0.3 to 5.0 mass %, more preferably 0.4 to 4.0 mass %, even more preferably 0.5 to 3.0 mass %, and particularly preferably 1.0 to 2.0 mass %, based on the total mass of the emulsion.

[0055] In a preferred embodiment of the present invention, the viscosity at 25°C and 1 atmospheric pressure is preferably 4000 mPa s or more, and more preferably 4000 to 100000 mPa s. The viscosity can be measured, for example, with a cone-plate viscometer (apparatus model name: RE-80R, manufacturer: Toki Sangyo, conditions: rotor: 3°×R14, measurement temperature: 25°C, rotation speed: 50 rpm, measurement time: 3 minutes).

[0056] In the Pickering emulsion of the present invention, in addition to the above-mentioned components, optional components that are usually used in cosmetics can be contained within a range that does not impair the effects of the invention. Examples of such optional components include anionic surfactants such as fatty acid soaps (sodium laurate, sodium palmitate, etc.), potassium lauryl sulfate, and alkyl sulfate triethanolamine ethers, cationic surfactants such as stearyl trimethylammonium chloride, benzalkonium chloride, and laurylamine oxide, imidazoline-based amphoteric surfactants (2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, etc.), betaine-based surfactants (alkyl betaine, aliphatic triethanolamine, etc.), and the like. midobetaine, sulfobetaine, etc.), amphoteric surfactants such as acylmethyltaurine, 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 ether, POE sorbitan fatty acid esters (POE sorbitan monooleate, polyoxyethylene sorbitan monostearate, etc.), POE Sorbitol fatty acid esters (POE-sorbitol 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 nonylphenyl ether, etc.), Pluronic 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, anhydrous silicic acid (silica), aluminum oxide, barium sulfate, etc., which may be surface-treated, inorganic pigments such as cobalt oxide, ultramarine blue, Prussian blue, and zinc oxide, which may be surface-treated,Composite pigments such as sintered iron oxide titanium dioxide, which may be surface-treated; pearling agents such as titanium mica, fish phosphorus foil, and 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, and Red No. 204, which may be laked; organic powders such as polyethylene powder, polymethyl methacrylate, nylon powder, and organopolysiloxane elastomer; lower alcohols such as ethanol and isopropanol; vitamin A or its derivatives; vitamin B6 hydrochloride, vitamin B6 tripalmitate, vitamin B6 dioctanoate, vitamin B2 or its derivatives, vitamin B, 12 , Vitamin B 15or its derivatives, vitamin B group, α-tocopherol, β-tocopherol, γ-tocopherol, vitamin E acetate and other vitamins, vitamin D group, vitamin H, pantothenic acid, pantethine, pyrroloquinoline quinone and other vitamins, para-aminobenzoic acid, para-aminobenzoic acid monoglycerol ester, N,N-dipropoxypara-aminobenzoic acid ethyl ester, N,N-diethoxypara-aminobenzoic acid ethyl ester, N,N-dimethylpara-aminobenzoic acid Benzoic acid derivatives such as ethyl benzoate, N,N-dimethyl paraaminobenzoic acid butyl ester, N,N-dimethyl paraaminobenzoic acid ethyl ester, and diethylaminohydroxybenzoylbenzoic acid hexyl; anthranilic acid derivatives such as homomenthyl-N-acetylanthranilate; salicylic acid and its sodium salts, amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, salicylic acid derivatives such as p-isopropanolphenyl salicylate, p-isopropanolphenyl salicylate, etc.; octyl cinnamate, ethyl 4-isopropyl cinnamate, methyl 2,5-diisopropyl cinnamate, ethyl 2,4-diisopropyl cinnamate, methyl 2,4-diisopropyl cinnamate, propyl p-methoxycinnamate, isopropyl p-methoxycinnamate, isoamyl p-methoxycinnamate, 2-ethylhexyl p-methoxycinnamate, cinnamic acid derivatives such as cinnamate (ethylhexyl methoxycinnamate, octyl paramethoxycinnamate), 2-ethoxyethyl-p-methoxycinnamate (cinoxate), cyclohexyl-p-methoxycinnamate, ethyl-α-cyano-β-phenylcinnamate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate (octocrylene), glyceryl mono-2-ethylhexanoyl-di-paramethoxycinnamate, ferulic acid and its derivatives;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 benzophenone derivatives such as 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)benzo Triazole;2-(2'-hydroxy-5'-methylphenylbenzotriazole;Dibenzalazine;Dianisoylmethane;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;2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 1-(3,4-dimethoxyphenyl Preferred examples of the ultraviolet absorbers include hydantoin derivatives such as 2-ethylhexyl dimethoxybenzylidene dioxoimidazolidinepropionate, phenylbenzimidazolazole sulfonic acid, terephthalidenedicamphor sulfonic acid, drometrizole trisiloxane, methyl anthranilate, bisethylhexyloxyphenol methoxyphenyl triazine, rutin and its derivatives, and oryzanol and its derivatives.

[0057] As described above, the Pickering emulsion of the present invention may contain a surfactant, but the content of the surfactant is preferably as small as possible. The content of the surfactant is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0% by mass.

[0058] The Pickering emulsion of the present invention is suitable for use as an external preparation for the skin, and is particularly preferably used as a sunscreen external preparation for the skin by taking advantage of the function of the ultraviolet absorbing agent. Among these, it is preferable to use it in cosmetics, and it is preferable to use it as a sunscreen, a makeup base, etc. EXAMPLES

[0059] In the following examples, partially hydrophobized silica was used as the hydrophobized powder. The partially hydrophobized silica was obtained by mixing silica fine particles (manufactured by AEROSIL, average primary particle diameter 12 nm (measurement method as described above)) with trimethylsilyl hydrophobizing agent. The M value of the partially hydrophobized silica was measured by the above-mentioned method and was 0. At room temperature (25°C), the emulsifying component (ii) (partially hydrophobic silica or surfactant) was dispersed in the aqueous phase component (i) shown in Table 1, and the oil phase component (iii) was added thereto with stirring to emulsify, thereby producing the oil-in-water emulsion compositions of the Examples and Comparative Examples.

[0060] [Table 1]

[0061] The above-mentioned method was able to produce the emulsion compositions of Example 1 and Comparative Examples 1 and 2. However, the above-mentioned production method was unable to produce the emulsion composition of Comparative Example 3. This result indicates that when the aqueous phase contains a large amount of polyol, it is preferable to form a Pickering emulsion in which the emulsion is emulsified with a powder rather than a surfactant.

[0062] The viscosity of the compositions of the examples and comparative examples was also measured. The results are shown in Table 1. The viscosity was measured using a cone-plate type viscometer (device model name: RE-80R, manufacturer: Toki Sangyo, conditions: rotor: 3°×R14, measurement temperature: 25° C., rotation speed: 50 rpm, measurement time: 3 minutes).

[0063] The emulsion compositions of Example 1 and Comparative Examples 1 and 2 that were successfully produced were subjected to the following tests.

[0064] <Test Example 1> Evaluation of sweat resistance The sweat resistance of the emulsion compositions of Example 1 and Comparative Examples 1 and 2 was evaluated by the following method. Each composition was applied to a 50 mm x 50 mm polymethylmethacrylate (PMMA) plate at a concentration of 0.2 g / cm 2 The PMMA plate was then immersed in artificial sweat and stirred at 150 rpm for 2 hours, after which it was removed from the water and the SPF value was measured in the same manner. The SPF value after immersion was divided by the SPF value before immersion to obtain the residual SPF value (%), which was used as an index of sweat resistance. The results are shown in Table 2.

[0065] <Test Example 2> Evaluation of high temperature stability The emulsion compositions of Example 1 and Comparative Examples 1 and 2 were evaluated for emulsion stability at high temperatures by the following method. After preparation, the emulsion was left to stand at 20°C for 24 hours, and then the emulsion particle size was measured (initial emulsion particle size). The emulsion particle size was determined by calculating the number average of the maximum diameters of 10 emulsion particles observed at 20°C under a magnification of 400x (10x eyepiece-40x objective) with an optical microscope OLYMPUS BX51. Subsequently, the emulsion composition was stored at 40°C for one week, and the average particle size of the oil phase in the emulsion composition (particle size after storage) was measured by the same method. As a result, the particle size after storage was 2 times or more the initial particle size as ×, 1.5 to 2.0 times as △, and 1.5 times or less as ◯, as shown in Table 2. The prepared emulsion composition was left to stand for one month at 40° C., and then the viscosity was measured by the above-mentioned method. The results are shown in Table 2.

[0066] <Test Example 3> Evaluation of transparency The visible light transmittance was measured for each of the emulsion compositions of Example 1 and Comparative Examples 1 and 2. The visible light transmittance was measured using a UV-Visible Spectrophotometer V660 (JASCO) and was defined as the visible light transmittance of 400 to 800 nm, which is generally known as visible light. The results are shown in Table 2.

[0067] <Test Example 4> Evaluation of apparent cool feeling The emulsion compositions of Example 1 and Comparative Examples 1 and 2 were subjected to a sensory evaluation of the apparent refreshing feeling and moisturizing property. The evaluation was carried out by 10 experienced researchers engaged in the sensory evaluation of cosmetics, who rated each evaluation item on a 5-point scale according to the following criteria, and the average score was taken as the evaluation score for each evaluation item. The results are shown in Table 2.

[0068] (Refreshing appearance) 5 points: Feels a very strong cooling sensation. 4 points: Feels very cool and refreshing. 3 points: A cooling sensation is felt, but weakly. 2 points: I finally feel a sense of coolness. 1 point: No cooling sensation.

[0069] (moisturizing properties) 5 points: Remains extremely moist even after a certain amount of time has passed after application. 4 points: Remains moist even after a certain amount of time has passed after application. 3 points: After application, skin feels slightly dry after a certain amount of time has passed. 2 points: After application, a feeling of dryness may be felt after a certain period of time has passed. 1 point: After application, a noticeable feeling of dryness is felt after a certain amount of time has passed.

[0070] [Table 2]

[0071] The Pickering emulsion of Example 1, which contains a total of 40 mass% polyol (62.5 mass% relative to the aqueous phase), has visible light transmittance, whereas the Pickering emulsion of Comparative Example 1, which contains a total of only 15 mass% polyol (23 mass% relative to the aqueous phase), and the emulsion composition of Comparative Example 2 do not have visible light transmittance. This result is believed to be due to the fact that the refractive index of the aqueous phase of the Pickering emulsion in Example 1 changes due to the large amount of polyol contained therein, and the refractive index becomes almost the same as the relative refractive index to the oil phase. As described above, the formulation of Comparative Example 3, which contained the same amount of polyol as in Example 1, was unable to form an emulsion composition. From the above, in order to form an emulsion composition having visible light transmittance, it is preferable to make it into the form of a Pickering emulsion emulsified with a powder.

[0072] In addition, the emulsion composition of Comparative Example 2, which was emulsified with a surfactant, showed an increase in emulsion particle size upon storage at high temperatures, while the emulsion compositions of Example 1 and Comparative Example 1, which are Pickering emulsions, showed a small increase in emulsion particle size (Table 2). Furthermore, when comparing the viscosity of the emulsion composition immediately after preparation shown in Table 1 with the viscosity of the emulsion composition after being left to stand for one month at 40°C shown in Table 2, a significant decrease in viscosity was observed in the emulsion composition of Comparative Example 2, which was emulsified with a surfactant, whereas no decrease in viscosity was observed in the emulsion compositions of Example 1 and Comparative Example 1, which are Pickering emulsions. This result indicates that, also from the viewpoint of high-temperature stability, in order to form an emulsion composition having visible light transmittance, it is preferable to make it in the form of a Pickering emulsion emulsified with a powder.

[0073] In addition, the Pickering emulsion of Example 1, which has permeability and an excellent visible cool feeling, has better sweat resistance than the Pickering emulsion of Comparative Example 1, which does not have permeability and has an inferior visible cool feeling (Table 2). This result indicates that the permeable Pickering emulsion of the present invention not only has a refreshing feel in appearance, but also has excellent sweat resistance.

[0074] <Test Example 5> Surface potential of partially hydrophobic silica Silica fine particles (manufactured by AEROSIL, average primary particle diameter 12 nm (measurement method as described above), hereinafter also referred to as untreated silica) and partially hydrophobized silica obtained by mixing the silica fine particles with a trimethylsilyl hydrophobizing agent were prepared.

[0075] This partially hydrophobic silica was dispersed in pure water or seawater (artificial seawater, GEX) at a concentration of 0.001 g / mL, and the zeta potential was measured using a zeta potential analyzer (ELS-Z, Otsuka Electronics). As a result, the zeta potentials of the partially hydrophobicized silica when dispersed in pure water and seawater were 16.84±2.18mV and 4.16±1.26mV, respectively (Figure 1).

[0076] This result indicates that the partially hydrophobic silica has a surface charge in the absence of ions, but becomes hydrophobic in the presence of ions as the surface charge is neutralized.

[0077] <Test Example 6> Seawater resistance test Using the partially hydrophobized silica used in Test Example 5, oil-in-water emulsions of Reference Example 1 and Comparative Example 4 were prepared according to the formulations shown in Table 3.

[0078] [Table 3]

[0079] The emulsions of Reference Example 1 and Comparative Example 4 were each mixed at 2.0 mg / cm 2 The plate was immersed in 150 mL of seawater and stirred for 2 hours at 150 rpm and 25° C. The amount of ethylhexyl methoxycinnamate dissolved in the seawater was then measured using HPLC.

[0080] As a result, the amount of ethylhexyl methoxycinnamate dissolved into seawater from the plate coated with the emulsion of Comparative Example 4 was 1327 μg. On the other hand, the amount of ethylhexyl methoxycinnamate dissolved into seawater from the plate coated with the emulsion of Reference Example 1 was 113.9 μg, which was 1 / 11 of the amount dissolved from the emulsion of Comparative Example 4 (FIG. 2).

[0081] This result indicates that the Pickering emulsion emulsified in pure water by partially hydrophobized silica with a surface charge has excellent resistance to aqueous solutions containing ions.

[0082] <Test Example 7> Observation of the cross section of the coating film (1) The cross-sectional appearances of the coating films of the emulsions of Reference Example 1 and Comparative Example 4 formed on the PMMA plates before and after immersion in seawater by the method of Test Example 6 were observed with a scanning electron microscope (SEM) (FIG. 3).

[0083] 3, most of the coating film of the emulsion of Comparative Example 4 peeled off after immersion in seawater, whereas the coating film of the emulsion of Reference Example 1 remained on the plate even after immersion in seawater.

[0084] The results of Test Examples 5 to 7 show that when the emulsion of Reference Example 1 comes into contact with an aqueous solution containing ions, the partially hydrophobic silica loses its surface charge and becomes hydrophobic, causing the emulsion coating film itself to aggregate, thereby improving the physical strength.

[0085] <Test Example 8> SPF measurement The SPF values ​​of the coating films of the emulsions of Reference Example 1 and Comparative Example 4 applied onto a PMMA plate were measured with an SPF analyzer before and after immersion in seawater in the same manner as in Test Example 6.

[0086] As a result, the SPF value of the coating film of the emulsion of Comparative Example 4 decreased to 70% after immersion in seawater, whereas the SPF value of the coating film of the emulsion of Reference Example 1 surprisingly increased to 140% after immersion in seawater (FIG. 4).

[0087] <Test Example 9> Measurement of scattering rate The emulsion of Reference Example 1 was applied to a quartz plate to a certain thickness, and the scattering rate of ultraviolet light before and after contact with seawater was measured using a spectrophotometer (V-600, JASCO). As a result, it was surprising that the coating film of the emulsion of Reference Example 1 showed an increased scattering rate of light in the ultraviolet region after contact with seawater (FIG. 5).

[0088] Considering the results of Test Example 5, the results of Test Example 9 show that the scattering rate of ultraviolet light increases due to aggregation of partially hydrophobic silica that has lost its surface charge and become hydrophobic after coming into contact with an aqueous solution containing ions.

[0089] In addition, when the results of Test Example 8 are taken into consideration together with the results of Test Example 9, it is shown that the scattering rate of ultraviolet light increased after contact with the aqueous solution containing ions, thereby increasing the optical path length within the coating film, and as a result, the efficiency of ultraviolet light absorption by the ultraviolet absorber (ethylhexyl methoxycinnamate) was improved.

[0090] The results of Test Examples 5 to 9 show that the Pickering emulsion of the present invention has excellent resistance to an aqueous solution containing ions.

[0091] <Test Example 10> Observation by electron microscope The oil-in-water Pickering emulsion of Reference Example 2, which was prepared according to the formulation shown in Table 4 using partially hydrophobized silica treated with a trimethylsilyl hydrophobizing agent in the same manner as in Test Example 1, was observed under a scanning electron microscope. The electron microscope image is shown in FIG.

[0092] [Table 4]

[0093] The secondary particle size of the partially hydrophobized silica in the Pickering emulsion of Reference Example 2 was calculated based on Fig. 6. As a result, the average secondary particle size of the silica was 50 nm or less. The Pickering emulsions of Reference Example 2 and Examples were produced by the same method using the same partially hydrophobized silica. Therefore, from the results of observation of the Pickering emulsion of Reference Example 2 with a scanning electron microscope, it can be inferred that the average secondary particle size of silica in the Pickering emulsions of Examples is also 50 nm or less.

[0094] <Test Example 11> Observation of the cross section of the coating film (2) Using partially hydrophobized silica treated with a trimethylsilyl hydrophobizing agent in the same manner as in Test Example 1, an emulsion of Comparative Example 5 was prepared according to the formulation shown in Table 5. The emulsions of Comparative Example 5 and Reference Example 1 prepared above were immersed in seawater in the same manner as in Test Example 6. Thereafter, the cross-section of the coating film of the emulsion after immersion was observed by a scanning electron microscope in the same manner as in Test Example 7. The electron microscope image is shown in FIG.

[0095] [Table 5]

[0096] As shown in Table 5, the emulsion of Comparative Example 5 contains a sufficient amount of surfactant (PEG-25 stearate) to maintain the emulsion system. Therefore, in the emulsion of Comparative Example 5, the partially hydrophobic silica is not adsorbed to the interface between the water phase and the oil phase, and is dispersed in the water phase by the action of the surfactant. In other words, the emulsion of Comparative Example 5 is not a Pickering emulsion. Therefore, when the coating film of the emulsion of Comparative Example 5 was brought into contact with seawater, the partially hydrophobic silica dispersed in the aqueous phase formed aggregates (areas surrounded by dotted lines in FIG. 7), but aggregation and hydrophobization of the entire coating film did not occur (FIG. 7).

[0097] This result indicates that the effect of the present invention cannot be obtained by simply dispersing surface-charged emulsified powder into an emulsion.

[0098] On the other hand, Reference Example 1 is a Pickering emulsion in which the emulsified state is stabilized by the adsorption of partially hydrophobic silica to the interface between the water phase and the oil phase. After the coating film of the Pickering emulsion of Reference Example 1 comes into contact with seawater, the emulsion droplets with partially hydrophobic silica adsorbed at the interface aggregate, causing the coating film itself to condense and become hydrophobic (Figure 7).

[0099] The above results indicate that the effect of the present invention, namely, excellent resistance to aqueous solutions containing ions, is brought about by the form of a Pickering emulsion stabilized by surface-charged emulsified powder.

[0100] <Test Example 8> Observation of the cross section of the coating film (3) The coating film of the Pickering emulsion of Reference Example 1 was immersed in pure water and seawater in the same manner as in Test Example 6. Electron microscope images of the cross section of the coating film before and after immersion in pure water or seawater are shown in FIG.

[0101] As shown in FIG. 8, the coating film of the Pickering emulsion of Reference Example 1 did not peel off even after immersion in seawater or pure water, and the porous structure was maintained. This result indicates that the coating film of the Pickering emulsion of the present invention also has excellent water resistance.

[0102] In addition, the thickness of the film separating the pores in the porous structure that appears in the cross section of the coating film of the Pickering emulsion in Reference Example 1 is approximately three times that of the film that separates the pores when immersed in seawater. This result indicates that the coating film of the Pickering emulsion of the present invention becomes highly aggregated upon contact with an aqueous solution containing ions, thereby increasing the hydrophobicity of the entire film. [Industrial Applicability]

[0103] The present invention is suitable for cosmetics.

Claims

1. The composition comprises an aqueous phase containing a polyol, an oil phase, and a powder, The powder is partially hydrophobized silica having an average secondary particle size of 200 nm or less, The visible light transmittance is 20% or more when the optical path length is 1 cm. A Pickering emulsion in which the emulsified state is stabilized by the partially hydrophobic silica being adsorbed to the interface between the water phase and the oil phase. (Note that the average secondary particle diameter is determined by measuring the maximum diameters of 2,500 or more secondary particles on a scanning electron microscope image and calculating the number average.)

2. 2. The Pickering emulsion according to claim 1, wherein the powder has a relative refractive index of 0.7 to 1.3 with respect to the oil phase.

3. 3. The Pickering emulsion according to claim 1, wherein the relative refractive index of the aqueous phase to the oil phase is from 0.8 to 1.

2.

4. The Pickering emulsion according to any one of claims 1 to 3, comprising 30% by mass or more of a polyol relative to the aqueous phase.

5. The Pickering emulsion according to any one of claims 1 to 4, comprising 0.1% by mass or more of a thickener relative to the aqueous phase.

6. The Pickering emulsion according to any one of claims 1 to 5, characterized in that the viscosity at 25°C and 1 atmospheric pressure is 4000 mPa·s or more.

7. The Pickering emulsion according to any one of claims 1 to 6, wherein the powder is a partially hydrophobized powder in which a portion of the surface is coated with a hydrophobizing agent.

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