Method for producing oily dispersion and cosmetic containing oily dispersion

Abstract

Provided are: a method for producing an oily dispersion containing inorganic oxide powder and a non-silicone-based oiling agent containing, as a treatment agent, at least one compound selected from an organosilicon compound, a higher fatty acid, a carboxylic acid-modified silicone, and a pyrrolidonecarboxylic acid-modified silicone, the method involving (1) a step for adding the inorganic oxide powder while heating, at a temperature of 40°C-120°C, the non-silicone-based oiling agent containing said treatment agent, and (2) a step for further mixing, at a temperature of 40°C-120°C, a dispersion product obtained by adding the total amount of the non-silicone-based oiling agent and the inorganic oxide powder; and a cosmetic containing the oily dispersion.

Description

Method for producing oily dispersion and cosmetic containing oily dispersion

[0001] The present invention relates to a method for producing an oil dispersion and a cosmetic preparation containing the oil dispersion. More specifically, the present invention relates to a method for producing an oil dispersion that can disperse inorganic oxide powder well in an oil even at a high solids concentration, and to a cosmetic preparation containing the oil dispersion produced by this method.

[0002] In general, in oil dispersions for cosmetics, pigments to be blended in makeup cosmetics such as foundation, eye shadow, and blush, as well as basic cosmetics such as sunscreen cosmetics, hair cosmetics, emulsions, and creams, are highly dispersed in advance in an oil medium. These oil dispersions for cosmetics are widely used due to their good handling properties, such as less scattering and contamination of the pigment during the preparation of the cosmetics, and no need for special mixing equipment because the pigment is already highly dispersed.

[0003] On the other hand, inorganic oxide powders have strong cohesive forces between the powders, making them difficult to disperse in oils as they are. Therefore, pigments used in oil-based dispersions are widely subjected to hydrophobic treatments in order to facilitate the dispersion of the inorganic oxide powder in oils. For example, known methods include coating the pigment surface with higher fatty acids, higher alcohols, hydrocarbons, or silicones such as silicone oils and silicone resins to impart hydrophobicity. Among these, many methods for hydrophobizing pigments using silicones as surface treatment agents have been established to date (see, for example, JP-A-60-163973 and JP-A-62-177070), and oil-based dispersions using these methods are also widely known (see, for example, JP-A-2002-80748, JP-A-2005-171145, and JP-A-2011 / 007668).

[0004] Furthermore, since inorganic oxide powders have a strong cohesive force between the powder particles, in order to suppress re-agglomeration after dispersion and maintain dispersion stability, it is common to disperse the inorganic oxide powder by adding a silicone-based dispersant such as polyether-modified silicone, a surfactant, or the like (see, for example, JP 2007-291379 A and JP 2012-184178 A).

[0005] However, in the method of hydrophobizing inorganic oxide powder, an oil-based dispersion cannot be prepared until the inorganic oxide powder has first been subjected to a step of surface treatment with a surface treatment agent, which presents a problem of complication.

[0006] Furthermore, when an oily dispersion obtained using a dispersant, surfactant, or the like is blended into a cosmetic, it may have adverse effects such as deteriorating the storage stability and cosmetic durability of the cosmetic.

[0007] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a method for producing an oily dispersion that can obtain an oily dispersion with excellent dispersibility of inorganic oxide powder, without the need to previously subject the inorganic oxide powder to surface treatment in order to increase its dispersibility in oil agents, and without the addition of a dispersant, and a cosmetic containing the oily dispersion produced by this method.

[0008] As a result of intensive research aimed at solving the above problems, the present inventors discovered that an oil-based dispersion with high powder dispersibility can be obtained by adding an inorganic oxide powder that has not been hydrophobized to a non-silicone oil agent containing at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones as a treating agent, while heating at a temperature of 40° C. to 120° C., and thus completed the present invention. Thus, the oil-based dispersion of the present invention contains an inorganic oxide powder that has not been hydrophobized (component (A)), a non-silicone oil (component (B)), and at least one compound (component (C)) selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones.

[0009] A method for producing an oil dispersion according to one embodiment of the present invention is characterized by comprising the steps of: (1) adding an inorganic oxide powder to a non-silicone oil agent while heating the non-silicone oil agent, which contains as a processing agent at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones, at a temperature of 40°C to 120°C; and (2) further mixing the dispersion to which the entire amount of the inorganic oxide powder has been added at a temperature of 40°C to 120°C.

[0010] In one embodiment of the method for producing an oil-based dispersion of the present invention, it is preferable to use a kneading mixer or a wet mixer / disperser for dispersion in step (2) of the production method.

[0011] One embodiment of the method for producing an oil-based dispersion of the present invention is a method for producing an oil-based dispersion, comprising: step (1) of adding inorganic oxide powder to a non-silicone-based oil, while heating the non-silicone-based oil, which contains as a processing agent at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidonecarboxylic acid-modified silicones, at a temperature of 40°C to 120°C; and step (2) of further mixing the dispersion to which the entire amount of inorganic oxide powder has been added at a temperature of 40°C to 120°C, followed by cooling the oil-based dispersion and further dispersing the mixture using a wet mixer / disperser.

[0012] In one embodiment of the method for producing the oil dispersion of the present invention, after step (2) of the above-mentioned production method, the oil dispersion is preferably cooled to room temperature (20°C to 30°C), and further dispersed using a wet mixer / disperser to produce the oil dispersion.

[0013] In the above aspect of the present invention, the solid content concentration of the inorganic oxide powder during production of the oil dispersion is preferably 25% by mass or more.

[0014] According to the present invention, the oil dispersion contains an inorganic oxide powder (component (A)) that has not been hydrophobized, a non-silicone oil (component (B)), and at least one compound (component (C)) selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones, in which component (A) is uniformly or substantially uniformly dispersed at a solids concentration of 25% by mass or more. Here, "uniformly or substantially uniformly dispersed" includes cases in which the dispersed particles in the oil dispersion are uniform and no aggregation is observed, and cases in which the dispersed particles in the oil dispersion are nearly uniform but slight aggregation is observed. The solids concentration of component (A) can preferably be 40% by mass or more and 80% by mass or less. Alternatively, the solids concentration of component (A) can be 40% by mass or more and 70% by mass or less.

[0015] Furthermore, the present invention relates to a cosmetic preparation containing the above-mentioned oily dispersion, or a cosmetic preparation containing the oily dispersion produced by the production method of the present invention.

[0016] Next, a method for producing an oily dispersion according to the present invention and specific embodiments of a cosmetic containing the oily dispersion produced by this method will be described. In this specification, the range "X to Y" means "X or more, Y or less." Unless otherwise specified, the operations are carried out under the conditions of room temperature (20°C to 30°C) and a relative humidity of 45 to 55% RH.

[0017] The method for producing an oil dispersion of the present invention is a method for producing an oil dispersion containing the following components (A) to (C): (A) inorganic oxide powder that has not been hydrophobized, (B) a non-silicone oil agent, and (C) at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones, the method comprising the steps of: (1) adding component (A) to an oil agent obtained by dissolving or dispersing component (C) in component (B) while heating the oil agent at a temperature of 40°C to 120°C; and (2) further mixing the dispersion to which the entire amount of component (A) has been added at a temperature of 40°C to 120°C.

[0018] According to the present invention, by adding an inorganic oxide powder that has not been hydrophobized while heating at a temperature of 40°C to 120°C to a non-silicone oil agent containing at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones as a treatment agent, an oil dispersion with a high solids concentration and high powder dispersibility can be obtained, and a cosmetic containing the same can be obtained.

[0019] The inorganic oxide powder that is not hydrophobized, which is component (A) of the present invention, is not particularly limited, but examples include inorganic oxides commonly used in cosmetics, such as silicic anhydride (silicon oxide), aluminum oxide, iron oxide (red iron oxide, yellow iron oxide, black iron oxide, etc.), titanium oxide, zinc oxide, cerium oxide, and bismuth oxide. When the objective is to achieve UV protection, fine particles of inorganic oxides such as titanium oxide, zinc oxide, iron oxide, cerium oxide, and bismuth oxide are used. These can also be used as a composite of two or more of these. However, none of them should be hydrophobized. Here, hydrophobization refers to a process in which the surface of the inorganic oxide powder is coated with an organic substance, such as a higher fatty acid, a higher alcohol, a hydrocarbon, or a silicone such as silicone oil or silicone resin, to impart hydrophobicity.

[0020] The particle size of the inorganic oxide is not particularly limited, but is, for example, in the range of 0.001 to 50 μm. The particle size is based on volume and can be measured using a laser diffraction particle size distribution analyzer.

[0021] The solids concentration of the inorganic oxide powder (component (A)) in the oil dispersion is not particularly limited, but is preferably 25% by mass or more, and more preferably 40 to 80% by mass, or 40 to 70% by mass. If the solids concentration of the inorganic oxide powder is less than 25% by mass, an oil dispersion in which the inorganic oxide powder has good dispersibility over time may not be obtained, while if it exceeds 80% by mass, the powder may aggregate and the dispersion itself may not be obtained.

[0022] In the present invention, the non-silicone oil agent of component (B) used as a dispersion medium is a medium for dispersing component (A), and is not particularly limited as long as it does not have a polysiloxane skeleton, and may be of any origin such as animal oil, vegetable oil, or organic oil, or may be in any state such as solid oil, semi-solid oil, liquid oil, or volatile oil, but liquid oils that are liquid at room temperature are preferred from the viewpoint of the dispersibility of component (A). For example, hydrocarbons, oils and fats, hardened oils, ester oils, lanolin derivatives, etc. can be used, and more specifically, hydrocarbons such as liquid paraffin, light liquid isoparaffin, dodecane, isododecane, tetradecane, isotetradecane, hexadecane, isohexadecane, squalane, vegetable squalane, petrolatum, polyisobutylene, polybutene, etc.; cetyl octanoate, isononyl isononanoate, isodecyl isononanoate, isotridecyl isononanoate, isononane Tricyclodecane methyl ester, (caprylic / capric acid) coconut alkyl ester, hexyl laurate, methylheptyl laurate, caprylyl laurate, decyl laurate, isopropyl myristate, methylheptyl myristate, 2-hexyldecyl myristate, octyldodecyl myristate, isopropyl palmitate, methylheptyl palmitate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, ethyl isostearate, isostearate Monoester oils such as isopropyl isostearate, isobutyl isostearate, decyl isostearate, methylheptyl isostearate, 2-hexyldecyl isostearate, 2-ethylhexyl hydroxystearate, octyldodecyl oleate, oleyl oleate, octyldodecyl ricinoleate, alkyl benzoate, and glyceryl isostearate; di(caprylic / capric)propanediol, neopentyl glycol diisononanoate, dicaprylate diester oils such as neopentyl glycol phosphate, propylene glycol dicaprate, glyceryl diisostearate, polyglyceryl diisostearate, propanediol diisostearate, di(phytosteryl / octyldodecyl) lauroyl glutamate, di(cholesteryl / behenyl / octyldodecyl) lauroyl glutamate, di(octyldodecyl / phytosteryl / behenyl) lauroyl glutamate, and neopentyl glycol dioctanoate;Examples include triester oils such as trimethylolpropane triisostearate, diglyceryl triisostearate, caprylic / capric triglyceride, glyceryl trioctanoate, macadamia nut oil, olive oil, castor oil, jojoba oil, avocado oil, and sunflower oil; ester oils such as pentaerythrityl tetraoctanoate, diglyceryl tetraisostearate, dipentaerythrityl tetraisostearate, and pentaerythritol tetraisostearate; and oil-soluble UV absorbers such as ethylhexyldimethyl p-aminobenzoate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, octocrylene, and dineopentyl-4'-methoxybenzalmalonate. One or more of these may be used. Of these, hydrocarbons and various ester oils are preferred.

[0023] In one embodiment of the present invention, the content of component (B) in the oil dispersion is not particularly limited, but is preferably 20 to 70% by mass, more preferably 25 to 65% by mass, from the viewpoint of dispersibility effects.

[0024] As component (C) of the present invention, at least one compound selected from the group consisting of organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidonecarboxylic acid-modified silicones is used as a treating agent. These may be used in combination of two or more types.

[0025] Examples of the organosilicon compound, component (C) of the present invention, include silylating agents or silane coupling agents having an organic group introduced therein, such as tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, isobutyltrimethoxysilane, n-decyltrimethoxysilane, n-octyltrimethoxysilane, octyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, dimethylpolysiloxysilazane, triethoxysilylethyl polydimethylsiloxyethyl dimethicone, and triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone.

[0026] The higher fatty acid, component (C) of the present invention, is not particularly limited, but is usually a fatty acid having 12 or more carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, palmitoleic acid, oleic acid, and linoleic acid. Isostearic acid, palmitoleic acid, oleic acid, and linoleic acid, which are liquid at room temperature, are preferred because they can reduce the viscosity of the oil dispersion.

[0027] The carboxylic acid-modified silicone, component (C) of the present invention, can be produced by known methods, such as a method of subjecting a dimethylpolysiloxane having Si—H groups to an addition reaction with an unsaturated carboxylic acid ester compound in the presence of a platinum catalyst, followed by saponification to form a carboxylic acid; a method of subjecting a dimethylpolysiloxane having Si—H groups to an addition reaction with an unsaturated carboxylic acid silyl ester or allyloxycarboxylic acid silyl ester in the presence of a platinum catalyst, followed by post-reaction hydrolysis to obtain the target product; and a method of subjecting a bis(hydroxycarbonylethyl)tetramethyldisiloxane to an equilibration reaction using a cyclic siloxane and an acidic catalyst to obtain a silicone modified at both ends with a carboxylic acid (Silicone Handbook, edited by Ito Kunio, Nikkan Kogyo Shimbun, pp. 166-167). A particularly suitable carboxylic acid-modified silicone for use in the present invention is, for example, ES-5800 Formulation Aid (manufactured by Dow Toray).

[0028] The pyrrolidone carboxylic acid-modified silicone, component (C) of the present invention, refers to a compound in which some of the siloxanes in a polymethylsiloxane are methyl(N-alkyl-pyrrolidone carboxylic acid)siloxanes or di(N-alkyl-pyrrolidone carboxylic acid)siloxanes, and is described as "PCA DIMETHICONE" in the "International Nomenclature of Cosmetic Ingredients" (INCI). A particularly suitable pyrrolidone carboxylic acid-modified silicone for the present invention is, for example, SENSASIL PCA-LQ-(AP) (Croda Japan).

[0029] In one embodiment of the present invention, the amount of component (C) in the oil dispersion is not particularly limited, but is preferably in the range of 1 to 10 parts by mass when the concentration of the inorganic oxide powder is 100 parts by mass. If the amount is less than 1 part by mass, the inorganic oxide powder may not be uniformly dispersed in the non-silicone oil agent, while if it exceeds 10 parts by mass, the feel and stability of the cosmetic may be impaired when the oil dispersion is incorporated into the cosmetic. Note that when two or more types of component (C) are used, the viscosity of the oil dispersion of the present invention can be reduced.

[0030] The method for producing the oil dispersion of the present invention is a production method which is carried out in the following order: Step (1) and Step (2).

[0031] Step (1): In step (1), the non-silicone oil of component (B), which contains at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones, dissolved or dispersed as component (C), is heated at a temperature of 40°C to 120°C, while the intended amount of inorganic oxide powder of component (A) is added to the non-silicone oil of component (B). Here, it is preferable to gradually add the inorganic oxide powder to the non-silicone oil. That is, it is preferable to add the inorganic oxide powder in multiple portions over a predetermined addition time rather than adding the entire amount all at once.

[0032] The temperature of the non-silicone oil is preferably maintained within the above temperature range while the inorganic oxide powder is being added. It is preferable to heat the non-silicone oil using an appropriate heating means so that the temperature is maintained within the above temperature range.

[0033] The time for adding the inorganic oxide powder to the non-silicone oil is, for example, 1 minute to 100 minutes.

[0034] The dispersion method for obtaining the oil dispersion in step (1) can be a method in which the inorganic oxide powder is added while stirring the non-silicone oil agent using a stirrer such as a homomixer or a disper. The rotation speed during stirring is not particularly limited as long as the dispersion proceeds well, but is, for example, 1000 rpm to 5000 rpm.

[0035] Step (2): The oil dispersion obtained in step (1) is further mixed at a temperature of 40°C to 120°C to obtain an oil-based dispersion. The mixing time in step (2) is preferably 2 hours or more from the viewpoint of dispersibility of the inorganic oxide powder in the non-silicone oil agent, and more preferably 2 to 10 hours, and even more preferably 2 to 5 hours, from the viewpoint of saturation of the effect. In step (2), dispersion may be continued using a homomixer, disperser, or the like, but it is preferable to use a kneading mixer capable of applying a higher shear force, such as a kneader mixer, Henschel mixer, roll kneader, or extruder kneader, or a wet mixer / disperser such as a propeller mixer, high-speed mixer, dissolver, ultemizer, wet jet mill, colloid mill, mass colloider, (wet) bead mill, sand mill, basket mill, or AD mill.

[0036] As for the temperature conditions during production in steps (1) and (2), it is preferable to heat the non-silicone oil and oil dispersion to a temperature of 40°C to 120°C. Temperatures below 40°C are not preferable because the inorganic oxide powder cannot be uniformly dispersed in the non-silicone oil. However, when a volatile hydrocarbon oil is used, it is preferable to carry out the heating at 60°C or less to prevent the hydrocarbon oil from volatilizing. Temperatures above 120°C are not preferable because yellow iron oxide and black iron oxide in the inorganic oxide powder may discolor.

[0037] After steps (1) and (2), it is preferable to cool the oil dispersion and then perform an additional dispersion step, since this further microparticulates the inorganic oxide powder and results in a more uniformly dispersed state in the oil agent. Cooling is preferably performed until the temperature drops below 40°C, and preferably to room temperature (20°C to 30°C). Examples of cooling methods include a method in which the dispersion is left to cool while continuing to stir; and a method in which the oil dispersion is cooled using a cooling means while continuing to stir. From the viewpoint of improving the dispersibility of the inorganic oxide powder in the oil dispersion, a wet mixer disperser is preferred as the disperser used for dispersion after cooling, and a wet bead mill is particularly preferred. Specific examples of wet mixer dispersers are as described above. The dispersion time for dispersion after cooling is, for example, 15 minutes to 5 hours, and may be 30 minutes to 3 hours.

[0038] Next, the cosmetic of the present invention will be described. By blending the oily dispersion prepared by the above-described production method, the cosmetic of the present invention can be prepared into a sunscreen or other cosmetic product that has a high solids concentration, good stability over time, and a high SPF value and transparency. Specific examples of the cosmetic product include makeup cosmetics such as foundation, eye shadow, and blush, as well as sunscreen cosmetics, hair cosmetics, emulsions, creams, and other basic cosmetics. The amount of the oily dispersion blended in the cosmetic product is not particularly limited, but is preferably 0.1 to 90% by mass of the cosmetic product.

[0039] Furthermore, the cosmetic of the present invention may contain ingredients that are commonly used in cosmetics, such as powders, surfactants, oils, gelling agents, polymers, cosmetic ingredients, moisturizers, pigments, preservatives, and fragrances, within the scope of not impairing the effects of the present invention.

[0040] The cosmetic composition of the present invention may be in any form, such as powder, emulsion, cream, stick, solid, spray, or multi-layered separated type.

[0041] Next, the present invention will be explained in more detail based on examples and comparative examples of an oil dispersion produced by the production method of the present invention and a cosmetic composition containing this oil dispersion, but the present invention is not limited to the following examples.

[0042] Example 1 1.2 g of isostearic acid (RADIACID0909, manufactured by Oleon) and 38.8 g of squalane were mixed and heated to 60°C. After confirming that the temperature had reached 60°C, 60 g of titanium oxide (MP-1133, manufactured by Teica Corporation) was added little by little over 10 minutes while stirring at 2000 rpm using a disper. After the entire amount of titanium oxide was added, the mixture was further stirred at 2000 rpm using a disper at 60°C for 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0043] Example 2 An oil dispersion of red iron oxide having a solid content of 60% by mass was obtained in the same manner as in Example 1, except that red iron oxide (R-516HP, manufactured by Titan Kogyo Co., Ltd.) was used instead of titanium oxide.

[0044] Example 3 An oil dispersion of yellow iron oxide having a solid content of 60% by mass was obtained in the same manner as in Example 1, except that yellow iron oxide (LL-100HP, manufactured by Titan Kogyo Co., Ltd.) was used instead of titanium oxide.

[0045] Example 4 An oily dispersion of black iron oxide with a solid content of 60% by mass was obtained in the same manner as in Example 1, except that black iron oxide (BL-100HP, manufactured by Titan Kogyo Co., Ltd.) was used instead of titanium oxide.

[0046] (Example 5) The oil dispersion obtained in Example 1 was cooled to room temperature (25°C) by leaving it to stand while continuing to stir, and then further dispersed and mixed for 1 hour using a wet bead mill (DYNO-MILL manufactured by Shinmaru Enterprises) under conditions of a peripheral speed of 10 m / s, φ0.5 mm zirconia beads, and a packing ratio of 70%, to obtain an oil dispersion of titanium oxide with a solid content concentration of 60 mass%. The obtained oil dispersion showed good dispersibility and storage stability at high temperatures.

[0047] Example 6 4 g of isostearic acid (RADIACID0909, manufactured by Oleon) and 46 g of isododecane were mixed and heated to 50°C. After confirming that the temperature had reached 50°C, 50 g of titanium dioxide microparticles (MT-100SA, manufactured by Teika Corporation) were added little by little over 9 minutes while stirring at 2000 rpm using a disper. After the entire amount of titanium dioxide microparticles was added, the mixture was dispersed for 2 hours using a wet bead mill (DYNO-MILL, manufactured by Shinmaru Enterprises) under conditions of a peripheral speed of 10 m / s, φ0.5 mm zirconia beads, a filling rate of 70%, and a temperature of 50°C, to obtain an oil-based dispersion of titanium dioxide microparticles with a solids concentration of 50% by mass. The obtained oil-based dispersion exhibited good dispersibility and storage stability at high temperatures.

[0048] Example 7 An oil dispersion of titanium oxide having a solid content concentration of 60 mass % was obtained in the same manner as in Example 1, except that the heating temperature was changed to 90°C.

[0049] Example 8 1.2 g of isostearic acid (RADIACID0909, manufactured by Oleon) and 38.8 g of cetyl octanoate were mixed and heated to 60°C. After confirming that the temperature had reached 60°C, 60 g of titanium oxide (MP-1133, manufactured by Teica Corporation) was added little by little over 10 minutes while stirring at 2000 rpm using a disper. After the entire amount of titanium oxide was added, stirring was continued for an additional 3 hours at 60°C, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0050] Example 9 An oily dispersion of titanium oxide having a solid content concentration of 60 mass % was obtained in the same manner as in Example 8, except that glyceryl trioctanoate was used instead of cetyl octanoate.

[0051] Example 10 2 g of octyltriethoxysilane (triethoxycaprylylsilane, AES-3083, manufactured by Shin-Etsu Chemical Co., Ltd.) and 58 g of light liquid isoparaffin were heated to 50°C. After confirming that the temperature had reached 50°C, 40 g of fine zinc oxide particles (MZ-500, manufactured by Teika Co., Ltd.) was added little by little over 8 minutes while stirring at 2000 rpm using a disper. After the entire amount of fine zinc oxide particles was added, stirring was continued for another 3 hours at a temperature of 50°C, and an oil-based dispersion of fine zinc oxide particles with a solids concentration of 40% by mass was obtained.

[0052] Example 11 1.4 g of octyltriethoxysilane (triethoxycaprylylsilane, AES-3083, manufactured by Shin-Etsu Chemical Co., Ltd.) and 28.6 g of light liquid isoparaffin were heated to 40°C. After confirming that the temperature had reached 40°C, 70 g of zinc oxide (ZnO-S05, manufactured by Sumitomo Osaka Cement Co., Ltd.) was added little by little over 11 minutes while stirring at 2000 rpm using a disper. After the entire amount of zinc oxide was added, stirring was continued for an additional 3 hours at a temperature of 40°C, and an oil-based dispersion of zinc oxide with a solids concentration of 70% by mass was obtained.

[0053] Example 12 1.2 g of octyltriethoxysilane (triethoxycaprylylsilane, AES-3083, manufactured by Shin-Etsu Chemical Co., Ltd.) and 38.8 g of liquid paraffin were heated to 110°C. After confirming that the temperature had reached 110°C, 60 g of titanium oxide (MP-1133, manufactured by Teika Co., Ltd.) was added little by little over 10 minutes while stirring at 2000 rpm using a disper. After the entire amount of titanium oxide was added, the mixture was further stirred at a temperature of 110°C for 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0054] Example 13 An oil dispersion of titanium oxide having a solid content concentration of 60 mass % was obtained in the same manner as in Example 12, except that the heating temperature was changed to 120°C.

[0055] Example 14 2 g of oleic acid and 58 g of liquid paraffin were heated to 90°C. After confirming that the temperature had reached 90°C, 40 g of finely divided zinc oxide particles (MZ-500, manufactured by Teika Corporation) were gradually added over 8 minutes while stirring at 2000 rpm using a disper. After the entire amount of finely divided zinc oxide was added, stirring was continued for another 3 hours at 90°C, yielding an oil-based dispersion of finely divided zinc oxide particles with a solids concentration of 40% by mass.

[0056] Example 15 1.0 g of isostearic acid (RADIACID0909, manufactured by Oleon) and 59.0 g of ethylhexyl methoxycinnamate were mixed and heated to 50°C. After confirming that the temperature had reached 50°C, 40 g of titanium oxide (MP-1133, manufactured by Teica Corporation) was added little by little over 8 minutes while stirring at 2000 rpm using a disper. After the entire amount of titanium oxide was added, the mixture was further stirred at a temperature of 50°C for 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 40% by mass.

[0057] Example 16 1.2 g of carboxylic acid-modified silicone (ES-5800 Formulation Aid, manufactured by Dow Toray Industries, Inc.) and 38.8 g of isododecane were mixed and heated to 50°C. After confirming that the temperature had reached 50°C, 60 g of titanium oxide (MP-1133, manufactured by Teica Corporation) was added little by little over 10 minutes while stirring at 2000 rpm using a disper mixer. After the entire amount of titanium oxide was added, the mixture was further stirred at 2000 rpm using a disper mixer at 50°C for 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0058] Example 17 1.2 g of pyrrolidone carboxylic acid-modified silicone (SENSASIL PCA-LQ-(AP), Croda Japan) and 38.8 g of isododecane were mixed and heated to 50°C. After confirming that the temperature had reached 50°C, 60 g of titanium oxide (MP-1133, manufactured by Teica Corporation) was added little by little over 10 minutes while stirring at 2000 rpm using a disper. After the entire amount of titanium oxide was added, the mixture was further stirred at 2000 rpm at 50°C for 3 hours using a disper, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0059] Comparative Example 1 An oil dispersion of titanium oxide having a solid content concentration of 60% by mass was obtained in the same manner as in Example 1, except that the temperature was changed from 60°C to 30°C.

[0060] (Comparative Example 2) Without using a treatment agent, 40 g of squalane was heated to 60°C. After confirming that the temperature had reached 60°C, 60 g of titanium oxide (MP-1133, manufactured by Teika Corporation) was added little by little over 10 minutes while stirring at 2000 rpm using a disper. After the entire amount of titanium oxide was added, stirring was continued for an additional 3 hours at a temperature of 60°C, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0061] (Comparative Example 3) Without using any treating agent, 40 g of isododecane was heated to 50°C. After confirming that the temperature had reached 50°C, 60 g of titanium oxide (OTS-2 CR-50, manufactured by Daito Kasei Kogyo Co., Ltd.) surface-treated with octyltriethoxysilane was added little by little over 10 minutes while stirring at 2000 rpm using a disper. After the entire amount of surface-treated titanium oxide was added, stirring was continued for an additional 3 hours at a temperature of 50°C, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0062] Next, the method for evaluating dispersion stability used in the examples will be described. The redispersibility of samples left one day after preparation and samples stored at 40°C for one month was visually observed (if particles had settled, the samples were shaken thoroughly).

[0063] Evaluation criteria after 1 day: ◯: Dispersed particles were uniform and no aggregation was observed. Δ: Dispersed particles were almost uniform, but slight aggregation was observed. ×: Dispersed particles were not uniform and significant aggregation was observed.

[0064] Evaluation criteria after 1 month storage: ◯: Dispersed particles were uniform and no aggregation was observed. Δ: Dispersed particles were almost uniform, but slight aggregation was observed. ×: Particles were not redispersed, and sedimentation or significant aggregation was observed.

[0065] The oil dispersions of Examples 1 to 17 and Comparative Examples 1 to 3 were evaluated by the above-mentioned evaluation methods, and the results are shown in Table 1.

[0066]

[0067] The oil dispersions of Examples 1 to 17, which are products of the present invention, showed good dispersibility both one day after production and after storage at 40°C for one month. It was also found that the oil dispersions of the present invention were superior in dispersibility, particularly in dispersibility over time, to the oil dispersions of Comparative Examples 1 to 3. It was also found that the oil dispersions of the present invention were superior in dispersibility over time to the case where a surface-treated inorganic oxide powder was used (Comparative Example 3).

[0068] Example 18: Oil-based foundation An oil-based foundation was obtained by dispersing and mixing the formulations shown in Table 2 using a homomixer. The dispersion stability of the oil-based foundation of Example 18 was good.

[0069]

[0070] Example 19: Sunscreen cream A sunscreen cream was obtained by the following method using the formulation shown in Table 3. The sunscreen cream of Example 19 had good dispersion stability.

[0071]

[0072] (Production method) Components (1) to (5) were mixed together. To this mixture, an aqueous solution of components (6) to (9), which had been mixed and dissolved in advance, was added while stirring with a homomixer to obtain the desired water-in-oil sunscreen cream.

[0073] The oil-based foundation of Example 18 and the sunscreen cream of Example 19 were cosmetics with good pigment dispersion stability.

[0074] The oil dispersion produced by the production method of the present invention is characterized by high uniform dispersibility of inorganic oxide powders, which tend to aggregate, in oil agents. Furthermore, this oil dispersion can provide cosmetics with good dispersion stability, and has great industrial applicability.

Claims

1. A method for producing an oil dispersion containing the following components (A) to (C): (A) inorganic oxide powder that has not been hydrophobized, (B) a non-silicone oil solution, and (C) at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones, the method comprising the steps of: (1) adding component (A) to an oil solution prepared by dissolving or dispersing component (C) in component (B) while heating the oil solution at a temperature of 40°C to 120°C; and (2) further mixing the dispersion to which the entire amount of component (A) has been added at a temperature of 40°C to 120°C.

2. The method for producing an oil dispersion according to claim 1, wherein the solids concentration of component (A) in the oil dispersion is 25% by mass or more.

3. The method for producing an oil-based dispersion according to claim 1 or 2, wherein a kneading mixer or a wet mixer / disperser is used for mixing in step (2).

4. The method for producing an oil-based dispersion according to claim 1 or 2, wherein after step (2), the oil-based dispersion is cooled and further dispersed using a wet mixer / disperser.

5. A method for producing an oil dispersion according to claim 3, wherein after all steps of the production method according to claim 3 have been completed, the oil dispersion is cooled and further dispersed using a wet mixer / disperser.

6. A cosmetic preparation containing an oily dispersion produced by the production method described in claim 1 or 2.

7. A cosmetic preparation containing the oily dispersion produced by the method of claim 3.

8. A cosmetic preparation containing the oily dispersion produced by the method of claim 4.

9. A cosmetic preparation containing the oily dispersion produced by the method of claim 5.

10. An oil-based dispersion comprising: (A) inorganic oxide powder that has not been hydrophobized; (B) a non-silicone oil; and (C) at least one compound selected from organosilicon compounds, higher fatty acids, carboxylic acid-modified silicones, and pyrrolidone carboxylic acid-modified silicones, in which component (A) is uniformly or substantially uniformly dispersed at a solids concentration of 25% by mass or more.

11. The oil dispersion of claim 10, wherein the solids concentration of component (A) is 40% by mass or more and 80% by mass or less of the oil dispersion, the content of component (B) is 20 to 70% by mass of the oil dispersion, and the content of component (C) is 1 to 10 parts by mass per 100 parts by mass of component (A).

12. A cosmetic preparation containing the oily dispersion according to claim 10 or 11.

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