JP2014201465A - Zinc oxide particle, dispersion and cosmetic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide zinc oxide particles capable of achieving an ultraviolet protection effect of PA++++ and to provide a cosmetic having a dispersion obtained using the same and an ultraviolet protection effect.SOLUTION: There are provided zinc oxide particles having a specific surface area of 20 to 30 m/g and a particle size distribution having peaks at 10 to 30 nm and 40 to 50 nm in the particle size distribution measured by a transmission electron microscope.

Description

The present invention relates to zinc oxide particles having a specific particle size distribution, and dispersions and cosmetics obtained using the same.

The adverse effect of ultraviolet rays on the skin has been regarded as a problem for many years, and ultraviolet protective cosmetics are required to prevent this. In such UV protective cosmetics, it is necessary to add a component having an UV shielding effect. As one of such components, zinc oxide particles are used (Patent Document 1, etc.).

As the fine zinc oxide particles, those having a specific surface area of 30 to 50 m ² / g, which is called fine zinc oxide, are generally used in the cosmetics field. However, in recent years, there has been a particular demand for shielding in the wavelength region of 320 to 400 nm called UVA. That is, it is said that ultraviolet rays in such a wavelength region cause loss of skin elasticity and appearance of wrinkles, thereby causing early aging of the skin.

In accordance with this, in recent years, in the PA showing the ability to block ultraviolet A waves, the Japan Cosmetic Industry Association has introduced a stage of PA ++++ with a PFA value of 16 or more. This is based on the fact that it has become possible to provide cosmetics having a high ultraviolet shielding ability as a result of the examination on the shielding ability of ultraviolet A waves. However, such a high ultraviolet shielding ability is often obtained mainly by using an organic ultraviolet shielding ability (for example, Patent Document 2).

Inorganic ultraviolet shielding agents used in cosmetics are also required to have a material that shields such ultraviolet A waves at a high level. However, a material that can achieve such a purpose with an inorganic material. Is not realized. In addition, conventional zinc oxide particles are also said to have UV-absorbing ability in the UVA region, but in order to obtain UV shielding ability at a high level of PA ++++ level, blending at a high concentration is required. It was difficult to achieve such an objective.

Patent Documents 3 and 4 describe zinc oxide particles having a specific surface area of 20 to 30 m ² / g or use thereof in cosmetics. These particles tended to have poor transparency due to a mixture of particles having a large particle size.

JP-A-7-118133 Japanese Patent No. 5001154 JP-A-2-208369 JP-A-2-289506

In view of the above, an object of the present invention is to provide zinc oxide particles capable of realizing PA ++++ level UV protection performance, a dispersion obtained by using the same, and a cosmetic having UV protection effects. To do.

The present invention has a specific surface area of 20 to 30 m ² / g and a particle size having peaks at 10 to 30 nm and 40 to 60 nm in the particle size distribution of primary particles measured by a transmission electron microscope (hereinafter referred to as TEM). Zinc oxide particles characterized by having a distribution.
The present invention has a specific surface area of 20 to 30 m ² / g, and has a particle size distribution having peaks at 10 to 30 nm and 40 to 60 nm in a particle size distribution measured by a transmission electron microscope, It is also zinc oxide particles obtained by oxidizing metal zinc vapor.

The present invention is also a zinc oxide particle dispersion obtained by dispersing the zinc oxide particles in a liquid medium.
The present invention is also an ultraviolet shielding cosmetic, which is obtained by using the zinc oxide particles.

The zinc oxide particles of the present invention have excellent ultraviolet shielding ability in the ultraviolet A wave region, and can be suitably used particularly as an ultraviolet shielding agent for cosmetics.

It is a figure which shows the particle size distribution of the zinc oxide particle of an Example and a comparative example. It is a figure which shows the ultraviolet-ray shielding property of the zinc oxide particle of an Example and a comparative example.

The present invention is described in detail below.
The present invention is zinc oxide particles having a specific surface area and particle size distribution. That is, in the zinc oxide particles having a slightly larger particle diameter than the normally used fine zinc oxide particles, the wavelength region of the ultraviolet rays to be shielded is shifted to the long wavelength region. Furthermore, by having the specific distribution as described above, there is an advantage that the ultraviolet shielding property can be enhanced by the zinc oxide having a small particle size entering between the particles of the zinc oxide having a large particle size.

The inventors have found that a cosmetic having remarkably excellent absorption characteristics can be obtained in the UVA wave region when the specific zinc oxide particles described above are used.

The zinc oxide of the present invention has a specific surface area of 20 to 30 m ² / g. If it is less than 20 m ² / g, the zinc oxide particles are too large, which is not preferable from the viewpoint of poor transparency, and if it exceeds 30 m ² / g, it is not preferable from the viewpoint that the ultraviolet shielding efficiency is deteriorated.

The specific surface area in the present specification is a value measured using a fully automatic specific surface area meter Macsorb HM model-1220 manufactured by Mountec Co., Ltd.

The zinc oxide particles of the present invention have a particle size distribution having peaks at 10 to 30 nm and 40 to 60 nm. The use of such a distribution is preferable in that the ultraviolet shielding region is widened. Furthermore, since the one where the peak of 10-30 nm is higher becomes high in transparency, it is preferable.

In the present specification, the particle size distribution refers to a value measured by a method of performing image analysis taken with a TEM and measuring the particle size of 300 primary particles. The particle diameter here means the diameter of the maximum inscribed circle with respect to the particles observed in the image, and the particle size distribution is a number distribution.

“With peaks at 10 to 30 nm and 40 to 60 nm” means that the maximum value is within the range of 10 to 30 nm and 40 to 60 nm when the particle diameter is plotted on the horizontal axis and the frequency is plotted on the vertical axis. It means that there is at least one each in the range. Further, another peak may exist in a particle size region outside the range.

The median diameter calculated from the particle size distribution is preferably 20 to 60 nm. By setting it as the said range, it is preferable at the point that ultraviolet-ray shielding property is high, maintaining visible light transparency.

The peak frequency of 10 to 30 nm calculated from the particle size distribution is preferably 5 to 40%. By setting it as the said range, it is preferable at the point that the shielding of an ultraviolet A wave area | region can be effectively performed, maintaining visible light transparency sufficiently.

The peak frequency of 40 to 60 nm calculated from the particle size distribution is preferably 5 to 40%. By setting it as the said range, it is preferable at the point that the shielding of an ultraviolet A wave area | region can be effectively performed, maintaining visible light transparency sufficiently.

The production method of the zinc oxide particles having the distribution as described above is not particularly limited. For example, in the French method, which is a well-known method for producing zinc oxide particles, various reaction times, reaction temperatures, etc. The zinc oxide particles described above can be obtained by adjusting the conditions.

In the French method, molten metal zinc is heated to about 1000 ° C, the generated zinc vapor is oxidized with air, sent to an air cooling tube with a blower, cooled, and separated and collected with a cyclone and bag filter. Is the method.

The zinc oxide particles as described above can be obtained by appropriately preparing reaction conditions in such a production method by the French method.

In addition to the production method according to the French method, zinc oxide particles having a desired particle size distribution can be obtained by mixing two or more zinc oxide particles having different particle sizes. The zinc oxide particles used in this case can be used in combination with those produced by any known method such as the French method, the American method, or the wet method. Moreover, what mixed the general process of baking etc. as needed after mixing may be used.

Furthermore, if necessary, the particle size distribution may be adjusted by sieving the zinc oxide particles used for mixing and / or the zinc oxide particles after mixing. By combining these various known methods, the above-described particle size distribution can be realized.

The zinc oxide particles obtained in this manner can be blended into cosmetics as they are, but may be further blended by applying a surface treatment by a known method for the purpose of imparting water repellency and oil repellency.

The type of surface treatment may be any material as long as it can be used in cosmetics, and is not particularly limited. For example, oxides such as silicon, zinc, titanium, aluminum, zirconium, tin, or water A coating layer of an inorganic compound such as an oxide, carbonate, or phosphate can also be provided. In addition, for the purpose of imparting water repellency, dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, methylmethoxypolysiloxane, dimethylpolysiloxane dihydrogen, etc. or copolymers thereof, acrylic silicone, triethoxysilyl Ethyl polydimethylsiloxyethyl dimethicone, triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone, alkylsilane, silane coupling agent, titanium coupling agent, aluminum coupling agent, stearic acid, lauric acid, oleic acid and their metal salts (aluminum Salt, zinc salt, magnesium salt, calcium salt, etc.), polyvinyl alcohol, ethylene glycol, propylene glycol, monoethanolamine, aminomethyl Lopanol, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, paraffin wax, polyethylene wax, amino silane, epoxy silane, methacryl silane, vinyl silane, mercapto silane, chloroalkyl silane, alkyl silane, fluoroalkyl silane, Examples include hexamethylsilazane, hexamethylcyclotrisilazane, trimethylolpropane, trimethylolethane, and pentaerythritol. These organic compounds may be used alone or in combination of two or more.

Further, these surface treatments may be performed in one kind or in combination of several kinds.

The coating amount of the surface treatment agent is preferably in the range of 0.1 to 30% by weight and more preferably in the range of 0.1 to 20% by weight with respect to the zinc oxide particles. When the content is 0.1% by weight or more, the effect of improving the functionality due to the surface treatment can be exhibited, and when the content is 30% by weight or less, the treatment can be performed without impairing the original lubricity. Is advantageous from a general point of view.

The surface treatment method is not particularly limited, but it can be coated by adding an inorganic compound or an organic compound in an aqueous dispersion of zinc oxide particles and optimizing the pH. In addition, to coat organic compounds that are not water-soluble or compounds that are difficult to adhere in water, surface treatment can be performed by adding the compound dry, grinding and mixing, and heating as necessary. .

The present invention is also a dispersion in which the above-described zinc oxide particles are dispersed in a liquid medium. That is, in order to achieve the object of the present invention and obtain a composition having a good ultraviolet shielding ability, it is necessary that the above-described zinc oxide particles are stably dispersed in a liquid medium. Usually, the ultraviolet shielding cosmetic has a form such as liquid, cream or cake, and the above-described zinc oxide particles are dispersed in a liquid medium. In order for the cosmetic to have a high PA value, in this dispersed state, the particle size distribution of zinc oxide is preferably in a specific controlled state.

In addition, storage and transportation from the production of zinc oxide raw materials to the production of cosmetics are required. When such storage and transportation is performed in the form of zinc oxide particles, there is a high possibility that aggregation between particles occurs and the specific surface area and particle size distribution cannot be within the above-described preferred range of the present invention. . For this reason, it is preferable at the point which can obtain cosmetics which have high ultraviolet-ray protection performance by storing and conveying in the state of the said dispersion as a dispersion disperse | distributed in the liquid medium.

The liquid medium is not particularly limited, and examples thereof include water, decamethylcyclopentasiloxane, alcohol, ester oil such as ethylhexyl palmitate, liquid paraffin such as hydrogenated polyisobutene, and dimethicone. Among these, it is preferable to use decamethylcyclopentasiloxane.

The dispersion preferably contains the zinc oxide particles in a proportion of 5 to 60% by weight with respect to the total amount of the dispersion.

The dispersion of the present invention preferably contains a dispersant. Thereby, the zinc oxide particles can be uniformly dispersed in the medium. The type of the dispersant that can be used in the present invention is not particularly limited. For example, polycarboxylic acid or a salt thereof, alkylsulfonic acid or a salt thereof, alkylbenzenesulfonic acid or a salt thereof, naphthalenesulfonic acid or a salt thereof, Polyether alkyl sulfonic acid or its salt, alkyl betaine, polyether or its derivative, polyether alkyl ether, polyoxyalkylene alkenyl phenyl ether, sorbitan fatty acid ester, polyether sorbitan fatty acid ester, polyether fatty acid ester, glycerin fatty acid ester, poly Ether hardened castor oil, polyether alkylamine, polyether modified silicone, polyglycerin modified silicone, polyhydric alcohols, alkyl modified polyhydric alcohol, etc. . Any of anionic, cationic, and nonionic materials may be used, but nonionic materials are preferred in order to prevent chemical reaction with zinc oxide particles. Two or more kinds of dispersions may be used in combination.

Especially as said dispersing agent, when using a silicone type material for a dispersion medium, it is preferable to use polyether modified silicone and polyglycerin modified silicone for a dispersing agent.

The amount of the dispersant is preferably 2 to 15% by weight with respect to the total amount of the dispersion. If the amount is less than this, it is difficult for the powder to adjust to water, and if it is more than this, the cost becomes disadvantageous.

Moreover, the manufacturing method of a dispersion is not specifically limited, It can obtain by the normal method of mixing and stirring each component mentioned above.

This invention is also the cosmetics obtained using the said zinc oxide particle. By blending such zinc oxide particles, a cosmetic having high UV protection performance can be obtained. More specifically, PA ++++ can be achieved by using an inorganic UV protection agent in the state of a cosmetic composition.

The cosmetic of the present invention preferably contains zinc oxide particles as described above in a proportion of 1 to 90% by weight. When the content is less than 1% by weight, it is not preferable in that the above-described effects cannot be obtained sufficiently. When the content exceeds 90% by weight, the powder according to the present invention becomes excessive, and the degree of freedom in blending as a cosmetic becomes small, which is not preferable. The upper limit is more preferably 60% by weight, still more preferably 40% by weight.

The cosmetic material of the present invention preferably has an ultraviolet transmittance of 20% or less at 380 nm. Thus, ultraviolet rays in a wavelength region that could not be sufficiently shielded by a conventional cosmetic containing zinc oxide can be sufficiently shielded by the cosmetic of the present invention.

Examples of the cosmetic of the present invention include foundations, makeup bases, eye shadows, blushers, mascara, lipsticks, sunscreen agents, and the like. The cosmetics of the present invention can be in any form of oily cosmetics, aqueous cosmetics, O / W type cosmetics, and W / O type cosmetics. Especially, it can be used especially suitably in makeup cosmetics and sunscreen agents such as foundations, makeup bases, and eye shadows.

The cosmetic of the present invention may be used in combination with any aqueous component or oily component that can be used in the cosmetic field, in addition to the components constituting the mixture. The aqueous component and the oil component are not particularly limited, and examples thereof include oils, surfactants, moisturizers, higher alcohols, sequestering agents, natural and synthetic polymers, water-soluble and oil-soluble polymers, UV shielding agents, Various extracts, inorganic and organic pigments, various powders such as inorganic and organic clay minerals, inorganic and organic pigments treated with metal soap or silicone, organic dyes and other colorants, preservatives, antioxidants, dyes, You may contain components, such as a thickener, a pH adjuster, a fragrance | flavor, a cooling agent, an antiperspirant, a disinfectant, and a skin activator. Specifically, it is possible to produce any desired cosmetic by a conventional method by arbitrarily blending one or more of the blending ingredients listed below. The compounding amounts of these compounding components are not particularly limited as long as the effects of the present invention are not impaired.

The oil content is not particularly limited. For example, 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, flaxseed oil, safflower oil, cottonseed oil, eno oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, cinnagari oil, Japanese kiri oil, jojoba oil, germ oil, triglycerin, glycerin trioctanoate, Glycerin triisopalmitate, cocoa butter, coconut oil, horse fat, hydrogenated coconut oil, palm oil, beef tallow, sheep fat, hydrogenated beef tallow, palm kernel oil, pork tallow, beef bone oil, owl kernel oil, hydrogenated oil, cow leg Fat, Owl, Hardened castor oil, Beeswax, Candelilla wax, Cotton wax, Carnauba wax, Bayberry wax, Ibotaro, Whale wax, Montan wax, Nukarou, Norin, Kapok wax, Lanolin acetate, Liquid lanolin, Sugar cane 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 POE hydrogenated lanolin alcohol ether, liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax and the like.

The lipophilic nonionic surfactant is not particularly limited. For example, sorbitan monooleate, sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate. Sorbitan fatty acid esters such as diglycerol sorbitan penta-2-ethylhexylate, diglycerol sorbitan tetra-2-ethylhexylate, mono-cotton oil fatty acid glycerin, glyceryl monoerucate, glyceryl sesquioleate, glyceryl monostearate, α, α Glycerol polyglycerin fatty acids such as glycerin '-oleic acid pyroglutamate, glyceryl monostearate malate, propylene glycol monostearate, etc. It can be exemplified glycol fatty acid esters, hardened castor oil derivatives, glycerin alkyl ether.

The hydrophilic nonionic surfactant is not particularly limited. For example, POE sorbitan fatty acid esters such as POE sorbitan monooleate, POE sorbitan monostearate, POE sorbitan tetraoleate, POE sorbite monolaurate, and POE sorbite mono POE sorbite fatty acid esters such as oleate, POE sorbite pentaoleate, POE sorbite monostearate, POE glycerin fatty acid esters such as POE glycerol monostearate, POE glycerol monoisostearate, POE glycerol triisostearate, POE POE fatty acid esters such as monooleate, POE distearate, POE monodiolate, ethylene glycol stearate, POE lauryl ether, POE POE alkyl ethers such as yl ether, POE stearyl ether, POE behenyl ether, POE 2 -octyldodecyl ether, POE cholestanol ether, POE alkyl phenyl ethers such as POE octyl phenyl ether, POE nonyl phenyl ether, POE dinonyl phenyl ether Pluronic type such as brulonic, POE / POP cetyl ether, POE / POP2-decyltetradecyl ether, POE / POP monobutyl ether, POE / POP hydrogenated lanolin, POE / POP alkyl ethers such as POE / POP glycerin ether, Tetronic PEO / TetraPOP ethylenediamine condensates, POE castor oil, POE hydrogenated castor oil, POE hydrogenated castor oil monoisos POE castor oil triisostearate, POE cured castor oil monopyroglutamic acid monoisostearic acid diester, POE castor oil cured castor oil derivatives such as POE cured castor oil maleic acid, POE beeswax and lanolin derivatives such as POE sorbite beeswax, Alkanolamides such as coconut oil fatty acid diethanolamide, lauric acid monoethanolamide, fatty acid isopropanolamide, POE propylene glycol fatty acid ester, POE alkylamine, POE fatty acid amide, sucrose fatty acid ester, POE nonylphenyl formaldehyde condensate, alkylethoxydimethylamine Examples thereof include oxide and trioleyl phosphate.

Examples of other surfactants include anionic surfactants such as fatty acid soaps, higher alkyl sulfates, POE lauryl sulfate triethanolamine, alkyl ether sulfates, alkyltrimethylammonium salts, alkylpyridinium salts, alkyl quaternary salts. Stabilizes cationic surfactants such as ammonium salts, alkyldimethylbenzylammonium salts, POE alkylamines, alkylamine salts, polyamine fatty acid derivatives, and amphoteric surfactants such as imidazoline-based amphoteric surfactants and betaine-based surfactants. And you may mix | blend in the range which does not have a problem in skin irritation.

The moisturizing agent is not particularly limited, and examples thereof include xylitol, sorbitol, maltitol, chondroitin sulfate, hyaluronic acid, mucoitin sulfate, caronic acid, atelocollagen, cholesteryl-12-hydroxystearate, sodium lactate, bile salt, dl- Examples thereof include pyrrolidone carboxylate, short-chain soluble collagen, diglycerin (EO) PO adduct, Izayoi rose extract, yarrow extract, and merirot extract.

The higher alcohol is not particularly limited, and examples thereof include linear alcohols such as lauryl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, myristyl alcohol, oleyl alcohol, cetostearyl alcohol, monostearyl glycerin ether (batyl alcohol), 2-decyl. Examples thereof include branched chain alcohols such as tetradecinol, lanolin alcohol, cholesterol, phytosterol, hexyldodecanol, isostearyl alcohol, octyldodecanol, and the like.

The sequestering agent is not particularly limited. For example, 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid tetrasodium salt, sodium citrate, sodium polyphosphate, metaphosphoric acid Examples thereof include sodium, gluconic acid, phosphoric acid, citric acid, ascorbic acid, succinic acid, edetic acid and the like.

The natural water-soluble polymer is not particularly limited. For example, arabia gum, tragacanth gum, galactan, guar gum, carob gum, caraya gum, carrageenan, pectin, agar, quince seed (malmello), alge colloid (guckweed extract), starch (rice, rice, Corn, potato, wheat), plant polymers such as glycyrrhizic acid, microbial polymers such as xanthan gum, dextran, succinoglucan and pullulan, and animal polymers such as collagen, casein, albumin and gelatin. .

The semi-synthetic water-soluble polymer is not particularly limited. For example, starch-based polymers such as carboxymethyl starch and methylhydroxypropyl starch, methylcellulose, nitrocellulose, ethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose, sodium cellulose sulfate, Examples thereof include cellulose polymers such as hydroxypropylcellulose, sodium carboxymethylcellulose (CMC), crystalline cellulose, and cellulose powder, and alginic acid polymers such as sodium alginate and propylene glycol alginate.

The synthetic water-soluble polymer is not particularly limited, and examples thereof include vinyl polymers such as polyvinyl alcohol, polyvinyl methyl ether, and polyvinyl pyrrolidone, and polyoxyethylene polymers such as polyethylene glycol 20,000, 40,000, and 60,000. Examples include polymers, polyoxyethylene polyoxypropylene copolymer polymers, acrylic polymers such as sodium polyacrylate, polyethyl acrylate, and polyacrylamide, polyethyleneimine, and cationic polymers.

The inorganic water-soluble polymer is not particularly limited, and examples thereof include bentonite, silicate AlMg (beegum), laponite, hectorite, and silicic anhydride.

The ultraviolet screening agent is not particularly limited. For example, paraaminobenzoic acid (hereinafter abbreviated as PABA), PABA monoglycerin ester, N, N-dipropoxy PABA ethyl ester, N, N-diethoxy PABA ethyl ester, N, N-dimethyl Benzoic acid UV screening agents such as PABA ethyl ester and N, N-dimethyl PABA butyl ester; Anthranilic acid UV screening agents such as homomenthyl-N-acetylanthranylate; Amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate , Salicylic acid UV screening agents such as phenyl salicylate, benzyl salicylate, p-isopropanol phenyl salicylate; octylcinnamate, ethyl-4-isopropylcinnamate, methyl-2,5- Isopropyl cinnamate, ethyl-2,4-diisopropyl cinnamate, methyl-2,4-diisopropyl cinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-methoxycinnamate, 2- Ethoxyethyl-p-methoxycinnamate, cyclohexyl-p-methoxycinnamate, ethyl-α-cyano-β-phenylcinnamate, 2-ethylhexyl-α-cyano-β-phenylcinnamate, glyceryl mono-2-ethylhexa Cinnamic acid-based ultraviolet screening agents such as noyl-diparamethoxycinnamate; 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone , 2, 2 ', 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4 -Benzophenone-based UV shielding agents such as phenylbenzophenone, 2-ethylhexyl-4'-phenyl-benzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, 4-hydroxy-3-carboxybenzophenone; (4′-methylbenzylidene) -d, l-camphor, 3-benzylidene-d, l-camphor, urocanic acid, urocanic acid ethyl ester, 2-phenyl-5-methylbenzoxazole, 2,2′-hydroxy- 5-methylphenylbenzotri Sol, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenylbenzotriazole), dibenzalazine, dianisoylmethane, 4-methoxy-4′- Examples thereof include t-butyldibenzoylmethane and 5- (3,3-dimethyl-2-norbornylidene) -3-pentan-2-one.

Other drug components are not particularly limited and include, for example, vitamin A oil, retinol, retinol palmitate, inosit, pyridoxine hydrochloride, benzyl nicotinate, nicotinamide, nicotinic acid DL-α-tocopherol, magnesium ascorbate phosphate, 2 Vitamins such as -O-α-D-glucopyranosyl-L-ascorbic acid, vitamin D2 (ergocaciferol), dl-α-tocopherol, dl-α-tocopherol acetate, pantothenic acid, biotin; estradiol, ethinylestradiol, etc. Hormones; amino acids such as arginine, aspartic acid, cystine, cysteine, methionine, serine, leucine and tryptophan; anti-inflammatory agents such as allantoin and azulene; whitening agents such as arbutin; astringents such as tannic acid; L Menthol, cooling agents and sulfur camphor such as, lysozyme chloride, can be mentioned pyridoxine chloride, and the like.

There are no particular limitations on the various extracts, for example, Dokudami extract, Oat extract, Merirot extract, Odorikosou extract, Licorice extract, Peonies extract, Soap extract, Loofah extract, Kina extract, Yukinoshita extract, Clara extract, Kouhone extract, Fennel Extract, Primrose Extract, Rose Extract, Giant Extract, Lemon Extract, Shikon Extract, Aloe Extract, Shobu Root Extract, Eucalyptus Extract, Horsetail Extract, Sage Extract, Thyme Extract, Tea Extract, Seaweed Extract, Cucumber Extract, Clove Extract, Raspberry Extract, Melissa Extract , Carrot extract, marronnier extract, peach extract, peach leaf extract, mulberry extract, cornflower extract, hamamelis extract, placenta extract, thymus extract, silk extract, licorice Mention may be made of the kiss and the like.

Examples of the various powders include bengara, yellow iron oxide, black iron oxide, titanium mica, iron oxide-coated mica titanium, titanium oxide-coated glass flakes and other bright colored pigments, mica, talc, kaolin, sericite, titanium dioxide, Examples thereof include inorganic powders such as silica and organic powders such as polyethylene powder, nylon powder, crosslinked polystyrene, cellulose powder, and silicone powder. Preferably, a part or all of the powder component is hydrophobized by a known method with a substance such as silicones, fluorine compounds, metal soaps, oils, acyl glutamates in order to improve sensory characteristics and cosmetic durability. May be used.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[Example 1]
Mix 5 kg of zinc oxide (specific surface area 15 m ² / g) obtained by oxidizing metal zinc vapor and 300 g of zinc oxide (specific surface area 52 m ² / g) obtained by heating zinc carbonate at 400 ° C. for 2 hours. By mixing, zinc oxide powder 1 (specific surface area 17 m ² / g) was obtained.

[Example 2]
Metal zinc vapor was oxidized to obtain zinc oxide powder A (specific surface area 10 m ² / g) and zinc oxide powder B (specific surface area 22 m ² / g). Zinc oxide powder 2 (specific surface area 18 m ² / g) was obtained by thoroughly mixing 2 kg of zinc oxide powder A and 4 kg of zinc oxide powder B with a mixer.

[Comparative Example 1]
Zinc carbonate was heated at 470 ° C. for 2 hours to obtain zinc oxide (zinc oxide 3: specific surface area 30 m ² / g).

(Particle size distribution)
Images taken with a transmission electron microscope were analyzed, the particle size of 300 primary particles was measured, and the number particle size distribution was measured. The results are shown in FIG. The particle diameter here means the diameter of the maximum inscribed circle with respect to the particles observed in the image, and the particle size distribution is a number distribution.

(Ultraviolet shielding)
15 g of zinc oxide powder, 2.5 g of a dispersant (Nopcosperth 44-C manufactured by San Nopco), 82.5 g of pure water, and 100 g of φ0.5 mm zirconia beads were placed in a mayonnaise bottle and dispersed for 30 minutes with a paint shaker. This liquid was diluted 0.09 wt% in pure water mixed with 1 wt% of a dispersant, placed in a 10 mm optical path length disposable cell, and the ultraviolet transmittance was measured with a spectrophotometer (V-570 manufactured by JASCO Corporation). The result is shown in FIG.

  The results shown in FIG. 2 indicate that the zinc oxide particles having a particle size distribution having peaks at 10 to 30 nm and 40 to 60 nm in the particle size number distribution have extremely excellent ultraviolet shielding properties.

(Sunscreen prescription)
A sunscreen was made with the following formulation.

No. No. 1 to 7 mixture. Add 11-14 mixture and stir well. No. 8-10 dispersions were added and stirred well to obtain an emulsion.

  The coating film of the obtained emulsion was made on a quartz plate with a wire bar (6 μm), and after drying, the transmission spectrum was measured with a spectrophotometer (JASCO V-600). Table 3 shows the results of confirming in vitro the PFA value of the prescribed sunscreen by converting the data with conversion software (manufactured by JASCO).

(PFA value evaluation in vivo)
As a result of measuring the PFA value based on the method of ISO 24442 Cosmetics-Sun protection test method-In vivo determination of sunscreen UVA protection of Formulation 1, the average of 10 samples was PFA 16.18.

Since the zinc oxide particles of the present invention have excellent shielding ability particularly in the ultraviolet A wave region, they can be suitably used particularly as an ultraviolet shielding agent for cosmetics.

Claims (4)

Specific surface area 20-30 m ² / g,
Zinc oxide particles characterized by having a particle size distribution having peaks at 10 to 30 nm and 40 to 60 nm in a particle size distribution measured by a transmission electron microscope. Specific surface area 20-30 m ² / g,
Zinc oxide particles obtained by oxidizing metal zinc vapor, characterized by having a particle size distribution having peaks at 10 to 30 nm and 40 to 60 nm in a particle size distribution measured by a transmission electron microscope. A zinc oxide particle dispersion obtained by dispersing the zinc oxide particles of claim 1 or 2 in a liquid medium. An ultraviolet shielding cosmetic obtained by using the zinc oxide particles according to claim 1.