JP7695502B2 - Zinc oxide particle dispersion and cosmetic preparation containing same - Google Patents

Description

The present invention relates to a zinc oxide particle dispersion and a cosmetic preparation containing the same.

Traditionally, titanium dioxide particles and zinc oxide particles have been used as UV scattering agents in sunscreen cosmetics and other products due to their high UV shielding properties and transparency. When untreated, these powders have a hydrophilic surface and may be washed away by sweat or rain. For this reason, especially in cosmetics, the particle surface is often treated to make it water repellent. In general, the primary particles of fine inorganic powders tend to aggregate, so they are widely used by dispersing them in a dispersion medium. In the cosmetics industry, silicone oil has been the mainstream formulation, so dispersions in which the surface of fine inorganic powders is silicone-treated and then dispersed in a silicone-based solvent are often used.

However, silicone-based dispersants are designed to have a large molecular weight to stabilize the dispersion, and they have problems in usability such as stickiness and poor spreadability. In recent years, non-silicone formulations have been increasing on the market.
Therefore, in the above-mentioned dispersions, there is a demand for non-silicone-based water-repellent surface treatment agents for inorganic powders and dispersing media.

In the above circumstances, a non-silicone dispersion of fine metal oxide particles surface-treated with trialkoxysilane has been proposed as a dispersion medium using a non-silicone oil agent (Patent Document 1).
Also, a non-silicone dispersion of fine metal oxide particles that have been surface-treated with an alkyl titanate has been proposed (Patent Document 2).

However, the water-repellent surface treatment agents such as the above-mentioned trialkoxysilanes and alkyl titanates are still not satisfactory in terms of cost, etc., and there is still room for improvement.

JP 2012-184178 A JP 2011-225419 A

In view of the above, the present invention aims to provide a non-silicone zinc oxide particle dispersion. It also aims to provide a non-silicone zinc oxide particle dispersion that has excellent dispersibility and stability over time even at high concentrations.

The present invention relates to
The following components (a) to (c):
The zinc oxide particle dispersion is characterized by containing: (a) zinc oxide particles surface-treated with 2.3 to 4.0 mol % of a fatty acid relative to the zinc oxide; (b) polyhydroxystearic acid; and (c) a non-silicone-based oil agent.

The fatty acid in the component (a) is preferably at least one selected from the group consisting of stearic acid, myristic acid, and palmitic acid.
The component (a) is preferably zinc oxide particles which have been surface-treated with one or both of aluminum hydroxide and hydrous silicic acid, and which have been further surface-treated with a fatty acid.

It is preferable that the non-silicone oil of component (c) above is an ester oil or a fruit oil.

The present invention also relates to a cosmetic preparation that contains the above-mentioned zinc oxide particle dispersion.

The present invention provides a non-silicone zinc oxide particle dispersion. Furthermore, the dispersion of the present invention has excellent dispersibility and stability over time even at high concentrations.

The present invention will be described in detail below.
The present invention relates to
The following components (a) to (c):
The zinc oxide particle dispersion is characterized by containing: (a) zinc oxide particles surface-treated with 2.3 to 4.0 mol % of a fatty acid relative to the zinc oxide; (b) polyhydroxystearic acid; and (c) a non-silicone-based oil agent.

The dispersion of the present invention is a non-silicone dispersion of fatty acid-treated zinc oxide particles having excellent dispersibility and stability over time, which can be produced by surface-treating zinc oxide particles with a specific amount of fatty acid in order to produce a dispersion consisting essentially of non-silicone materials. Even if the zinc oxide particles in the dispersion have a relatively high concentration, the dispersion has excellent dispersibility and stability over time.
In particular, by using a non-silicone oil agent and a fatty acid which is a naturally derived component, a dispersion with less environmental impact can be obtained.
Therefore, the dispersant of the present invention is a non-silicone type having high stability, and is suitable for use in cosmetics.

In the present invention, zinc oxide particles, which are inorganic powders that block ultraviolet scattering agents, are used as component (a). Zinc oxide is preferred because it has high transparency and excellent ultraviolet scattering performance.

The zinc oxide particles preferably have an average primary particle size of 100 nm or less. If the particle size of the zinc oxide particles exceeds 100 nm, the hiding power is large, the particles become white, and the transparency is low. The lower limit of the average primary particle size of the zinc oxide particles is not particularly limited, but is usually 5 nm.
The average primary particle size of zinc oxide particles is the average value of 200 particle sizes calculated from the specific surface area value according to the BET method.
The primary particle size of zinc oxide particles corresponds to the diameter of a sphere having the same surface area as the specific surface area determined by the BET method. That is, the particle size is a value calculated by the following formula from the specific surface area: Sg measured by a fully automatic BET specific surface area measurement device Macsorb (manufactured by Mountech) and the true specific gravity: ρ of zinc oxide.
Particle diameter (μm) = [6/(Sg×ρ)]
(Sg (m ² /g): specific surface area, ρ (g/cm ³ ): true specific gravity of particles)
In addition, the true specific gravity ρ of the particles was calculated using 5.6, which is the true specific gravity of zinc oxide.

The shape of the zinc oxide particles can be any shape, such as spherical, rod-like, needle-like, spindle-like, plate-like, etc. For shapes other than spherical, the above average primary particle diameter is determined by the length of the minor axis in the case of rod-like, needle-like, and spindle-like particles, and by the average diameter of the maximum inscribed circle of the surface in the case of plate-like particles.

The zinc oxide that can be used as a raw material is not particularly limited, and zinc oxide produced by known methods such as the French method and the American method can be used, but zinc oxide produced by the French method is particularly preferred because it contains fewer impurities. Zinc oxide produced by the precursor method, in which carbonates are heated and fired, is also more preferred because it has fine particles.

The zinc oxide particles constituting the component (a) of the present invention have a surface treatment layer made of a fatty acid on the surface thereof. As the water-repellent surface treatment agent, a fatty acid having high environmental adaptability is most preferable.
The surface treatment referred to here is a water-repellent treatment for reducing the affinity of the zinc oxide particle surface for water, and surface treatment using a material that is easily soluble in water or disperses in water after treatment does not fall under the "water-repellent treatment" of the present invention.

The fatty acid used in the present invention is preferably one that has strong water repellency. Compounds that form some kind of chemical bond with inorganic powder are preferred, but even compounds that physically adsorb can provide a certain degree of effect.
The fatty acid is preferably a higher fatty acid having 10 to 30 carbon atoms, since this can further improve the dispersibility of titanium dioxide particles in the dispersion. Specifically, it is preferably at least one type selected from saturated fatty acids such as stearic acid, myristic acid, lauric acid, palmitic acid, etc., and unsaturated fatty acids such as oleic acid.
Among these, stearic acid, myristic acid, and palmitic acid are particularly preferred from the viewpoints of their simple structure, low cost, high stability, and strong water repellency.
In order to obtain a dispersant with a smaller environmental impact, it is preferable to use a fatty acid derived from a plant.

The amount of fatty acid coating is preferably such that the zinc oxide particles can be uniformly coated. Specifically, it is preferably 2.3 to 4.0 mol% relative to the zinc oxide. By setting the amount within this range, the zinc oxide particles can be uniformly coated, water repellency can be imparted to the zinc oxide, and sufficient dispersibility and stability over time in the dispersion can be ensured. In addition, by preventing the amount of coating from becoming excessive, it is possible to prevent excess fatty acid from being liberated, which can lead to poor dispersibility or foaming in the dispersion. In addition, it is presumed that the viscosity does not increase due to the small amount of fatty acid liberated.
The lower limit is more preferably 2.5 mol % and the upper limit is more preferably 3.7 mol %.

A method for coating the surface of zinc oxide particles with a fatty acid can be, for example, by adding and mixing the fatty acid and zinc oxide particles in a solvent such as isopropyl alcohol or ethanol, and then drying and pulverizing the mixture.

In addition, the zinc oxide particles used in the present invention are preferably those whose particle surfaces are coated with other inorganic compounds, i.e., the zinc oxide particles that have been surface-treated with other inorganic compounds are preferably further surface-treated with fatty acids.
The coating material may be a known inorganic surface treatment material, for example, one or more of oxides or hydroxides of Al, Si, Zr, Sn, or the like.
By first treating the surface with these, the fatty acid can be more easily attached to the surface of the zinc oxide particles.

In addition, zinc oxide particles have the problem that zinc ions dissolve over time, which can destroy the emulsion system when incorporated into cosmetics, and that the surface catalytic activity of zinc oxide can denature other ingredients. However, coating with an inorganic compound can prevent the zinc ions from leaking out, and for such applications (such as cosmetics), coating with an inorganic compound is preferable.

In particular, it is preferable to use a material that has been surface-treated with one or both of aluminum hydroxide and hydrous silicate, as these are harmless to the environment and human body and have a high degree of activity suppression.

The coating amount of the inorganic surface treatment material is preferably 1 to 30% by mass based on the zinc oxide, since this range provides sufficient activity suppression and has little effect on the properties of the zinc oxide.
The lower limit is more preferably 3% by mass, and the upper limit is more preferably 20% by mass.

The surface treatment method using the inorganic surface treatment material is not particularly limited and can be performed by any commonly known method.

In the present invention, the component (a) is preferably contained in a proportion of 40 to 80% by mass based on the total amount of the dispersion. The effects of the present invention are particularly remarkable within this blending amount range.
The lower limit is more preferably 45% by mass, and further preferably 50% by mass.

In particular, in the present invention, even if the concentration of component (a) in the dispersion is relatively high, at 45 mass% or more, the dispersibility is good, the viscosity of the dispersion is low, and the viscosity is maintained over time.

The dispersion of the present invention contains polyhydroxystearic acid as component (b), which functions as a dispersant and is preferred in that it allows component (a) to be well dispersed in a non-silicone oil agent.
The use of polyhydroxystearic acid is particularly preferred in that good dispersion can be achieved even with a small amount, and that the ultraviolet-shielding inorganic powder having a water-repellent surface treatment layer is less likely to be washed away by water during use.

The hydroxyl group of hydroxystearic acid is preferably bonded to the carbon at position 12, and the degree of polymerization of hydroxystearic acid is preferably 3 to 12, and more preferably 4 to 8. Commercially available products include Salacos HS-6C (manufactured by Nisshin Oillio Co., Ltd.) and ARLACEL P-100 (manufactured by Uniqema Co., Ltd.).

The amount of polyhydroxystearic acid in the dispersion is preferably 0.1 to 10% by mass. The lower limit is more preferably 1% by mass, and the upper limit is even more preferably 7% by mass or less. The above ratios are particularly preferred in that they increase the solvent content and provide high compatibility with cosmetic formulations.

The dispersion of the present invention contains a non-silicone oil as component (c). The non-silicone oil is a medium for dispersing component (a) and is an oil that does not have a polysiloxane skeleton. A liquid oil that is liquid at room temperature (15 to 25°C) is suitable from the viewpoint of the dispersibility of component (a). Examples include ester oil, fruit oil, and other oils and fats. Among these, ester oil and fruit oil are suitable because they are easy to use when used in cosmetics. Specifically, the following can be mentioned, and one or more types can be used.

The above ester oils include ethylhexyl palmitate, isopropyl isostearate, ethyl oleate, octyldodecyl oleate, octyldodecyl myristate, diisostearyl malate, glyceryl tricaprylate, isooctyl isononanoate, isotridecyl isononanoate, isononyl isononanoate, ethylhexyl isononanoate, propylene glycol dicaprate, neopentylene glycol dicaprate, neopentylene glycol diethylhexanoate, cetyl ethylhexanoate, glyceryl tri-2-ethylhexanoate, jojoba oil, isopropyl myristate, isopropyl palmitate, isotridecyl isononanoate, polyglyceryl diisostearate, diglyceryl triisostearate, glyceryl tribehenate, hexa(hydroxystearic acid/stearic acid /rosin acid) dipentaerythrityl, neopentyl glycol dioctanoate, cholesteryl isostearate, cholesteryl hydroxystearate, cholesteryl stearate, cholesteryl lanoline fatty acid, phytosteryl oleate, N-lauroyl-L-glutamic acid di(cholesteryl, behenyl, octyldodecyl), N-lauroyl-L-glutamic acid di(phytosteryl, 2-octyldodecyl), etc.

The above-mentioned fruit oils include olive fruit oil, lily of the valley fruit oil, fennel fruit oil, caraway fruit oil, pepper fruit oil, coriander fruit oil, juniper fruit oil, vanilla fruit oil, bergamot fruit oil, lemon fruit oil, etc.

Other oils and fats mentioned above include safflower oil, soybean oil, evening primrose oil, grape seed oil, rosehip oil, coconut oil, almond oil, sesame oil, wheat germ oil, corn oil, cottonseed oil, avocado oil, camellia oil, persic oil, castor oil, peanut oil, hazelnut oil, macadamia nut oil, medfoam oil, cocoa butter, shea butter, wood wax, coconut oil, palm oil, palm kernel oil, beef tallow, horse tallow, mink oil, milk fat, egg yolk oil, turtle oil, Japan wax, camellia oil, etc.

The amount of the component (c) in the dispersion is preferably 5 to 60% by mass. This ratio is advantageous in that the component (c) is easily compatible with oils when blended into cosmetics and the like.
The lower limit is more preferably 10% by mass, and the upper limit is more preferably 55% by mass.

In addition to the above components, the dispersion of the present invention may contain preservatives, pH adjusters, pure water, etc., depending on the purpose.

The dispersion of the present invention preferably has an initial viscosity of 2500 mPa·s or less, as determined by the following evaluation method. If the viscosity is in this range, the dispersion has low viscosity and beads can be easily separated after dispersion.
Also, it is more preferable that the viscosity is 2400 mPa·s or less.

(Initial Viscosity Evaluation Method)
7 ml of the dispersion immediately after production was placed in a 9 ml screw bottle, and rotated at 60 rpm using a B-type viscometer (Tokyo Keiki, TVB-10) with a rotor No. 4, and the viscosity (25° C.) was measured 60 seconds after the start of rotation.

The dispersion of the present invention preferably has a viscosity after 7 days of 5000 mPa·s or less as measured by the following evaluation method. If the viscosity is within this range, the dispersion is not too high, and the dispersion is easy to take out of a container and easy to handle.
Also, it is more preferable that the viscosity is 4,500 mPa·s or less.

(Method for evaluating viscosity over time)
7 ml of the dispersion immediately after production was placed in a 9 ml screw bottle and stored in a thermostatic chamber at 40° C. for 7 days. The dispersion was rotated at 60 rpm using a B-type viscometer (TVB-10 manufactured by Tokyo Keiki) with a rotor No. 4, and the viscosity (40° C.) was measured 60 seconds after the start of rotation.

The method for producing the dispersion of the present invention is not particularly limited.
Specifically, for example, the components (a) to (c) can be used as raw materials, and the raw materials can be mixed and stirred with other components to obtain the composition.

The dispersion of the present invention is preferably an oil-based dispersion that is substantially free of water. Furthermore, the content of components other than the above-mentioned components (a) to (c) is preferably 1% by weight or less, and more preferably 0.5% by weight or less. The dispersion may also consist of only the above-mentioned components (a) to (c). The dispersion of the present invention can be used particularly as a raw material for the production of cosmetics. For this reason, it is preferable that the dispersion contains as few components other than those mentioned above as possible, so as to avoid any restrictions on the formulation.

The zinc oxide particle dispersion of the present invention may contain inorganic particles other than zinc oxide. The inorganic particles that can be used in combination are not particularly limited, but examples thereof include titanium dioxide.
In particular, when titanium dioxide is used in combination with zinc oxide, the problem of thickening tends to become prominent, and therefore the effect of the present invention becomes more prominent when used in combination with titanium dioxide. When zinc oxide is used as an ultraviolet ray shielding agent in an ultraviolet ray protective cosmetic composition, titanium dioxide particles with a different ultraviolet ray shielding range may be used in combination, and the present invention is also useful in such cases.

In the present invention, the titanium dioxide particles used in combination are not particularly limited, but it is preferable to use titanium dioxide particles whose surface has been treated with a fatty acid.
The amount of fatty acid coated on the titanium dioxide particles is preferably 4.0 to 8.5% by mass relative to the titanium dioxide particles. The type of fatty acid may be the same as that used for zinc oxide.
Similarly to zinc oxide particles, it is preferable to treat the particles with aluminum hydroxide or hydrous silicic acid and then with a fatty acid.

The surface treatment of titanium dioxide particles can be carried out in the same manner as that described above for the treatment of zinc oxide particles.

The titanium dioxide particles preferably have an average primary particle size of 200 nm or less. If the particle size of the titanium dioxide particles exceeds 200 nm, the hiding power is large, the particles become white, and the transparency is low. The lower limit of the average primary particle size of the titanium dioxide particles is not particularly limited, but is usually 5 nm.
The average primary particle size of the titanium dioxide particles is calculated by measuring the particle sizes of 200 randomly selected particles under an electron microscope and averaging the particle sizes.

The shape of titanium dioxide particles is not particularly limited, and any shape such as sphere, rod, needle, spindle, plate, etc. The above-mentioned average primary particle diameter in the case of a shape other than sphere is defined as the average length of the minor axis side in the case of rod-shaped, needle-shaped, and spindle-shaped particles, and is defined as the average diagonal length of the face in the case of plate-shaped particles.
The titanium dioxide particles preferably have a major axis diameter/minor axis diameter (aspect ratio) of not more than 9. The aspect ratio of the titanium dioxide particles is calculated as the average major axis diameter/minor axis diameter value of 200 particles randomly selected under an electron microscope.

When inorganic fine particles other than zinc oxide, such as titanium dioxide, are used, the total amount of component (a) and the inorganic fine particles other than zinc oxide, such as titanium dioxide, is preferably 40 to 70% by weight based on the total amount of the zinc oxide particle dispersion.
Furthermore, when inorganic particles other than zinc oxide, such as titanium dioxide, are used, the inorganic particles may be blended in an amount that does not impair the object of the present invention. For example, the blended amount of inorganic particles other than zinc oxide, such as titanium dioxide, is preferably no more than twice the mass of zinc oxide.

The dispersion of the present invention is preferably a non-silicone dispersion. Non-silicone means that it does not substantially contain silicone-based materials, and preferably does not substantially contain silicone-based oils, silicone-based surfactants, or inorganic particles that have been surface-treated with silicone-based surface treatment agents.

The dispersion of the present invention is suitable for use in cosmetics. The type of cosmetic is not particularly limited, but it can be blended into skin care products, hair products, makeup products, UV protection products, and other cosmetics that are applied externally to the skin or hair. There is also no particular limit to the form of the product, but it can be applied in the form of a milky lotion, cream, solid, paste, gel, multi-layered, mousse, spray, etc.

The cosmetic of the present invention may be used in combination with any aqueous or oily component that can be used in the field of cosmetics as other raw materials of the dispersion of the present invention. The aqueous and oily components are not particularly limited, and examples thereof include oils, surfactants, moisturizing agents, higher alcohols, sequestering agents, water-soluble natural and semi-synthetic, synthetic polymers, water-soluble and oil-soluble polymers, organic ultraviolet screening agents, various extracts, etc.
In addition, as necessary, various powders such as inorganic and organic pigments, inorganic and organic clay minerals, inorganic and organic pigments treated with metal soap or silicone, coloring agents such as organic dyes, and other medicinal ingredients such as preservatives, antioxidants, coloring agents, thickeners, emulsifying thickeners, pH adjusters, fragrances, cooling agents, antiperspirants, germicides, skin activators, anti-inflammatory agents, whitening agents, and film-forming agents may be contained. Specifically, the cosmetic preparation of interest can be produced by a conventional method by arbitrarily mixing one or more of the ingredients listed below. The amount of these ingredients is not particularly limited as long as it is within a range that does not impair the effects of the present invention.
Furthermore, inorganic powders of ultraviolet scattering agents such as titanium dioxide and cerium oxide may be used as long as they do not impair the object of the present invention.
The cosmetic preparation of the present invention may be a non-silicone-based formulation, or may be a formulation containing silicone-based materials, such as silicone-based oils, including methyl silicone and methyl phenyl silicone, depending on the purpose.

The oils are not particularly limited, and examples thereof 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, 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, cacao butter, coconut oil, horse tallow, hydrogenated coconut oil, palm oil, beef tallow, mutton tallow, hydrogenated beef tallow, palm kernel oil, lard, beef bone fat, Japan wax kernel oil, hydrogenated oil, beef leg fat, Japan wax, hydrogenated castor oil, beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, and bayberry wax. Examples include botara wax, whale wax, montan wax, bran wax, lanolin, kapok wax, lanolin acetate, liquid lanolin, sugar cane wax, lanoline fatty acid isopropyl, hexyl laurate, reduced lanolin, jojoba wax, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanoline fatty acid polyethylene glycol, POE hydrogenated lanolin alcohol ether, liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, propylene glycol dicaprate, ethylhexyl palmitate, isotridecyl isononanoate, etc.

The surfactant is not particularly limited, and examples thereof include lipophilic nonionic surfactants, hydrophilic nonionic surfactants, and other surfactants.
The lipophilic nonionic surfactant is not particularly limited, and examples thereof include sorbitan fatty acid esters such as sorbitan monooleate, sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, diglycerol sorbitan penta-2-ethylhexyl acid, and diglycerol sorbitan tetra-2-ethylhexyl acid; glycerin monocottonseed oil fatty acid glycerin, glycerin monoerucate, glycerin sesquioleate, glycerin monostearate, α,α'-oleic acid pyroglutamic acid glycerin, and glycerin monostearate malic acid; propylene glycol fatty acid esters such as propylene glycol monostearate; hydrogenated castor oil derivatives; and glycerin alkyl ethers.

The hydrophilic nonionic surfactant is not particularly limited, and examples thereof include POE sorbitan fatty acid esters such as POE sorbitan monooleate, POE sorbitan monostearate, and POE sorbitan tetraoleate (e.g., polysorbate 60), POE sorbitan fatty acid esters such as POE sorbitan monolaurate, POE sorbitan monooleate, POE sorbitan pentaoleate, and POE sorbit monostearate, POE sorbitan fatty acid esters such as POE glycerin monostearate, POE glycerin monoisostearate, and POE glycerin triisostearate. POE glycerin fatty acid esters such as stearate, POE fatty acid esters such as POE monooleate, POE distearate, POE dioleate, and ethylene glycol distearate, POE alkyl ethers such as POE lauryl ether, POE oleyl ether, POE stearyl ether, POE behenyl ether, POE 2-octyldodecyl ether, and POE cholestanol ether, and POE alkyl phenyl ethers such as POE octylphenyl ether, POE nonylphenyl ether, and POE dinonylphenyl ether. POE·POP alkyl ethers such as POE·POP cetyl ether, POE·POP 2-decyltetradecyl ether, POE·POP monobutyl ether, POE·POP hydrogenated lanolin, POE·POP glycerin ether, etc.; tetraPOE·tetraPOP ethylenediamine condensates such as Tetronic, POE castor oil, POE hydrogenated castor oil, POE hydrogenated castor oil monoisostearate, POE hydrogenated castor oil triisostearate, POE hydrogenated castor oil monopyroglutamic acid monoisostearyl Examples of such fatty acids include POE hydrogenated castor oil diesters, POE hydrogenated castor oil derivatives such as POE hydrogenated castor oil maleic acid, POE beeswax/lanolin derivatives such as POE sorbitol beeswax, coconut oil fatty acid diethanolamide, lauric acid monoethanolamide, alkanolamides such as fatty acid isopropanolamide, POE propylene glycol fatty acid esters, POE alkylamines, POE fatty acid amides, sucrose fatty acid esters, POE nonylphenyl formaldehyde condensates, alkylethoxydimethylamine oxides, and trioleyl phosphates.

The above-mentioned other surfactants may include, for example, anionic surfactants such as fatty acid soaps, higher alkyl sulfate ester salts, POE triethanolamine lauryl sulfate, and alkyl ether sulfate ester salts; cationic surfactants such as alkyl trimethyl ammonium salts, alkyl pyridinium salts, alkyl quaternary ammonium salts, alkyl dimethyl benzyl ammonium salts, POE alkyl amines, alkyl amine salts, and polyamine fatty acid derivatives; and amphoteric surfactants such as imidazoline-based amphoteric surfactants and betaine-based surfactants, within a range that does not cause problems in terms of stability and skin irritation.

The above-mentioned moisturizing agents are 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 salts, dl-pyrrolidone carboxylate, short-chain soluble collagen, diglycerin (EO) PO adduct, Rosa rugosa extract, Achillea millefolium extract, and Melilot extract.

The above-mentioned higher alcohols are not particularly limited, and examples thereof include straight-chain alcohols such as lauryl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, myristyl alcohol, oleyl alcohol, and cetostearyl alcohol, and branched-chain alcohols such as monostearyl glycerin ether (batyl alcohol), 2-decyltetradecinol, lanolin alcohol, cholesterol, phytosterol, hexyldodecanol, isostearyl alcohol, and octyldodecanol.

The sequestering agent is not particularly limited, and examples thereof include 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid tetrasodium salt, sodium citrate, sodium polyphosphate, sodium metaphosphate, gluconic acid, phosphoric acid, citric acid, ascorbic acid, succinic acid, edetic acid, etc.

The above-mentioned natural water-soluble polymers are not particularly limited, and examples thereof include plant-based polymers such as gum arabic, tragacanth gum, galactan, guar gum, carob gum, karaya gum, carrageenan, pectin, agar, quince seed, algae colloid (cassow extract), starch (rice, corn, potato, wheat), and glycyrrhizic acid; microbial polymers such as xanthan gum, dextran, succinoglucan, and pullulan; and animal-based polymers such as collagen, casein, albumin, and gelatin.

Semi-synthetic water-soluble polymers are not particularly limited, and examples thereof include starch-based polymers such as carboxymethyl starch and methylhydroxypropyl starch, cellulose-based polymers such as methyl cellulose, nitrocellulose, ethyl cellulose, methylhydroxypropyl cellulose, hydroxyethyl cellulose, sodium cellulose sulfate, hydroxypropyl cellulose, sodium carboxymethyl cellulose (CMC), crystalline cellulose, and cellulose powder, and alginic acid-based polymers such as sodium alginate and propylene glycol alginate.

Synthetic water-soluble polymers are not particularly limited, and examples include vinyl polymers such as polyvinyl alcohol, polyvinyl methyl ether, and polyvinylpyrrolidone; polyoxyethylene polymers such as polyethylene glycol 20,000, 40,000, and 60,000; polyoxyethylene-polyoxypropylene copolymer polymers; acrylic polymers such as sodium polyacrylate, polyethyl acrylate, and polyacrylamide; polyethyleneimine; and cationic polymers.

Inorganic water-soluble polymers are not particularly limited, but examples include bentonite, AlMg silicate (beegum), laponite, hectorite, and silicic anhydride.

The organic UV blocking agent is not particularly limited, and examples thereof include benzoic acid UV blocking agents such as para-aminobenzoic acid (hereinafter abbreviated as PABA), PABA monoglycerin ester, N,N-dipropoxy PABA ethyl ester, N,N-diethoxy PABA ethyl ester, N,N-dimethyl PABA ethyl ester, and N,N-dimethyl PABA butyl ester; anthranilic acid UV blocking agents such as homomenthyl-N-acetylanthranilate; and salicylic acid UV blocking agents such as amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, and p-isopropanol phenyl salicylate. Agent: Ethylhexyl p-methoxycinnamate, 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-ethoxyethyl p-methoxycinnamate, cyclohexyl p-methoxycinnamate, ethyl α-cyano-β-phenylcinnamate, 2-ethylhexyl α-cyano-β-phenylcinnamate, glyceryl mono-2-ethylhexanoyl di-para-methoxycinnamate cinnamate and other cinnamic acid-based ultraviolet screening agents; 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-phenylbenzophenone, 2-ethylhexyl-4'-phenyl-benzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, 4-hydroxy-3-carboxybenzophenone Benzophenone-based ultraviolet screening agents such as benzophenone; 3-(4'-methylbenzylidene)-d,l-camphor, 3-benzylidene-d,l-camphor, urocanic acid, urocanic acid ethyl ester, 2-phenyl-5-methylbenzoxazole, 2,2'-hydroxy-5-methylphenylbenzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, dibenzalazine, dianisoylmethane, 4-methoxy-4'-t-butyldibenzoylmethane, 5-(3,3-dimethyl-2-norbornylidene)-3-pentan-2-one, etc.

The various extracts are not particularly limited, and examples thereof include Houttuynia cordata extract, Phellodendron bark extract, Melilot extract, Lamium extract, Licorice extract, Peony extract, Soapwort extract, Loofah extract, Cinchona extract, Saxifrage extract, Sophora flavescens extract, Water hyacinth extract, Fennel extract, Primrose extract, Rose extract, Rehmannia extract, Lemon extract, Lithospermum root extract, Aloe extract, Calamus root extract, Eucalyptus extract, Horsetail extract, Sage extract, Thyme extract, Tea extract, Seaweed extract, Cucumber extract, Clove extract, Rubus idaeus extract, Melissa extract, Carrot extract, Horse chestnut extract, Peach extract, Peach leaf extract, Mulberry extract, Cornflower extract, Hamamelis extract, Placenta extract, Thymus extract, Silk extract, Licorice extract, etc.

The above-mentioned various powders include luster color pigments such as red iron oxide, yellow iron oxide, black iron oxide, titanium mica, iron oxide-coated titanium mica, and titanium oxide-coated glass flakes; inorganic powders such as mica, talc, kaolin, sericite, titanium dioxide, and silica; and organic powders such as polyethylene powder, nylon powder, cross-linked polystyrene, cellulose powder, and silicone powder. Preferably, in order to improve sensory properties and cosmetic durability, part or all of the powder components may be treated to be water-repellent by a known method with substances such as silicones, fluorine compounds, metal soaps, oils, and acyl glutamates.

Other medicinal ingredients are not particularly limited, and examples include vitamins such as vitamin A oil, retinol, retinol palmitate, inositol, pyridoxine hydrochloride, benzyl nicotinate, nicotinamide, DL-α-tocopherol nicotinate, magnesium ascorbyl phosphate, 2-O-α-D-glucopyranosyl-L-ascorbic acid, vitamin D2 (ergocaciferol), dl-α-tocopherol, dl-α-tocopherol acetate, pantothenic acid, and biotin; hormones such as estradiol and ethinyl estradiol; 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; cooling agents such as L-menthol and camphor, sulfur, lysozyme chloride, and pyridoxine chloride.

The cosmetic of the present invention is not particularly limited in its manufacturing method, and may be manufactured by a manufacturing method that corresponds to the form of the cosmetic. Specifically, for example, the cosmetic can be obtained by mixing the dispersion of the present invention with other components.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" are by mass % and "parts by mass" without any particular limitation.

(Production Examples 1 to 12)
Surface-treated zinc oxide particles having the composition shown in Table 1 were prepared by the manufacturing method described below, and each powder was evaluated for "water repellency," and the results are also shown in Table 1. The mol % of fatty acid in Table 1 is based on zinc oxide alone excluding Al and silicic acid.

(Note 1) FINEX-40A (manufactured by Sakai Chemical Industry Co., Ltd.) (zinc oxide average primary particle size 27 nm, aluminum hydroxide 4.5%, hydrous silicic acid 4.5%)
(Note 2) Reagent grade stearic acid, plant-derived (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
(Note 3) Reagent grade myristic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

(Manufacturing method)
Component 2 or 3 was mixed with isopropyl alcohol in an amount three times the amount (by mass) of the respective component, and dissolved by stirring with a stirrer. The solution of component 2 or 3 and component 1 were thoroughly mixed in a plastic bag, and heat-treated at 120°C for 16 hours in a vent-type dryer. The dried product was pulverized in a coffee mill to obtain fatty acid-treated zinc oxide particles.

(Evaluation Method 1) Water Repellency: 50 mL of distilled water was placed in a 100 mL beaker, 1.0 g of fatty acid-treated zinc oxide particles was floated therein, and the water was stirred 10 times with a spatula, and the turbidity of the water was visually observed and evaluated according to the following evaluation criteria.
〇: The water is clear and not cloudy. △: The water is slightly cloudy and translucent. ×: The water is cloudy.

As shown in Table 1, Production Examples 2 to 6 and 8 to 12, which have a fatty acid content of 2.3 mol% or more, exhibited excellent water repellency, while Production Examples 1 and 7, which have a fatty acid content of less than 2.3 mol%, produced slightly cloudy water and had insufficient water repellency.

(Examples 1 to 8 and Comparative Examples 1 to 9)
Dispersions of fatty acid-treated zinc oxide particles having the compositions shown in Tables 2 and 3 were prepared by the manufacturing method described below. Each sample was evaluated for "initial viscosity" and "viscosity after aging at 40°C". The results are also shown in Tables 2 and 3.
(Production of fatty acid-treated titanium dioxide particles used in Examples 7 and 8)
5 g of stearic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 15 g of isopropyl alcohol and dissolved by stirring with a stirrer. The resulting solution was thoroughly mixed with 100 g of fine titanium dioxide particles (manufactured by Sakai Chemical Industry Co., Ltd., STR-100C, particle diameter: minor axis 20 nm, major axis 100 nm, aluminum hydroxide 10%) in a plastic bag and heat-treated at 120°C for 16 hours in a vent-type dryer. The dried product was pulverized with a coffee mill to obtain fatty acid-treated titanium dioxide particles (fatty acid content relative to titanium dioxide: 5.6%).

(Note 1) ARLACEL P-100 (Uniqema)
(Note 2) CROPURE OL (manufactured by Croda Japan)
(Note 3) PALMESTER 1543 (manufactured by Miyoshi Oil Co., Ltd.)

(Note 1) ARLACEL P-100 (Uniqema)
(Note 2) CROPURE OL (manufactured by Croda Japan)
(Note 3) PALMESTER 1543 (manufactured by Miyoshi Oil Co., Ltd.)

(Manufacturing method)
The fatty acid-treated zinc oxide particles, component 12 or 13, and polyhydroxystearic acid were placed in a mayonnaise bottle in the proportions shown in Tables 2 and 3, and φ0.5 mm zirconia beads were added in the same amount as the total amount of the above components, and then mixed and treated with a paint shaker (manufactured by Red Devil Co., Ltd.) for 30 minutes. The beads were then separated to obtain a fatty acid-treated zinc oxide particle dispersion.

(Evaluation method 2) 7 ml of the dispersion immediately after production was placed in a screw bottle with an initial viscosity of 9 ml, and rotated at 60 rpm using a B-type viscometer (Tokyo Keiki, TVB-10) with a rotor No. 4, and the viscosity (25° C.) was measured 60 seconds after the start of rotation.

(Evaluation method 3) After viscosity dispersion at 40°C, 7 ml of the dispersion immediately after production was placed in a 9 ml screw bottle and stored in a 40°C thermostatic chamber for 7 days. The viscosity was then measured at 60 seconds after the start of rotation using a B-type viscometer (Tokyo Keiki, TVB-10) with a rotor No. 4 at 60 rpm.

From the results of the above Examples and Comparative Examples, it was found that the dispersion of the present invention had good dispersibility of the surface-treated zinc oxide particles and was stable over time, even when the concentration of the surface-treated zinc oxide particles was high.
In contrast, in the dispersions of the comparative examples, the surface-treated zinc oxide particles were not uniformly dispersed compared to those of the examples, or aggregated over time, and were therefore not suitable as dispersants.
In addition, the dispersions of the comparative examples had high initial viscosities, and some had viscosities so high that beads could not be separated after dispersion, or the viscosity increased significantly over time, turning into a gel, making it impossible to measure the viscosity.

The dispersion of the present invention can be suitably used by incorporating it into cosmetics.

Claims (5)

The following components (a) to (c):
A zinc oxide particle dispersion comprising: (a) zinc oxide particles surface-treated with 2.3 to 4.0 mol % of a fatty acid relative to the zinc oxide; (b) polyhydroxystearic acid; and (c) a non-silicone oil agent. The zinc oxide particle dispersion according to claim 1, characterized in that the fatty acid in component (a) is at least one selected from the group consisting of stearic acid, myristic acid, and palmitic acid. The zinc oxide particle dispersion according to claim 1 or 2, characterized in that the component (a) is zinc oxide particles that have been surface-treated with one or two of aluminum hydroxide and hydrous silicate, and further surface-treated with a fatty acid. The zinc oxide particle dispersion according to any one of claims 1 to 3, characterized in that the non-silicone oil agent of component (c) is an ester oil or a fruit oil. A cosmetic preparation comprising the zinc oxide particle dispersion according to any one of claims 1 to 4.