Method for producing oily dispersion and cosmetic blended with the oily dispersion

Abstract

To provide a method for producing an oily dispersion having excellent dispersibility of an inorganic oxide powder without subjecting an inorganic oxide powder to pre-surface treatment to increase dispersibility in a hydrocarbon oil solution and to provide a cosmetic blended with the oily dispersion.SOLUTION: There are provided: an oily dispersion in which an easily coagulable inorganic oxide powder has a characteristic of high dispersibility in a hydrocarbon oil. In addition, the oily dispersion provides a cosmetic having good dispersion stability. There is provided: a method for producing an oily dispersion containing an inorganic oxide powder and a hydrocarbon oil comprising at least one compound selected from an ester oil, an organic titanate compound, a homopolymer of a hydroxylated fatty acid and a lecithin derivative as a treatment agent, which comprises a step (1) of gradually adding an inorganic oxide powder while heating a hydrocarbon oil containing the treatment agent at a temperature of 70°C to 120°C and a step (2) of mixing a dispersion obtained by adding the total amount of the hydrocarbon oil and the inorganic oxide powder at a temperature of 70°C to 120°C; and a cosmetic blended with the oily dispersion produced by the production method.SELECTED DRAWING: None

Description

[Technical Field]

[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 be dispersed in an oil agent even if it has a high solid content by adding an inorganic oxide powder to a hydrocarbon oil containing at least one compound selected from ester oil, an organic titanate compound, a homopolymer of a hydroxy fatty acid, and a lecithin derivative at a specific temperature, and to a cosmetic preparation containing the oil dispersion produced by this production method. [Background technology]

[0002] In general, oil dispersions for cosmetics are prepared by pre-dispersing pigments in an oily medium to a high degree, the pigments being blended in makeup cosmetics such as foundations, eye shadows, and blushes, as well as basic cosmetics such as sunscreen cosmetics, hair cosmetics, emulsions, and creams. For this reason, 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 pigments are already highly dispersed.

[0003] Furthermore, inorganic oxide powders have strong cohesive forces between the powders, making them difficult to disperse in oil solutions as they are. Therefore, pigments used in oil dispersions are widely subjected to hydrophobic treatments to facilitate the dispersion of inorganic oxide powders in oil solutions. For example, methods are known in which the pigment surface is coated with silicones, such as higher fatty acids, higher alcohols, hydrocarbons, 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, Patent Documents 1 and 2), and oil dispersions using these methods are also widely known (see, for example, Patent Documents 3, 4, and 5).

[0004] Furthermore, since inorganic oxide powders have a strong cohesive force between the powder particles, it is common to disperse the inorganic oxide powder by adding a silicone-based dispersant such as polyether-modified silicone or a surfactant in order to suppress re-agglomeration after dispersion and maintain dispersion stability (see, for example, Patent Documents 6 and 7). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 163973 / 1983 [Patent Document 2] Japanese Patent Application Laid-open No. 62-177070 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-80748 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-171145 [Patent Document 5] Re-tabled publication No. 2011 / 007668 [Patent Document 6] Japanese Patent Application Laid-Open No. 2007-291379 [Patent Document 7] Japanese Patent Application Laid-Open No. 2012-184178 Summary of the Invention

[0006] 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. Furthermore, when an oily dispersion obtained using a dispersant, surfactant, or the like is blended into a cosmetic, there is a risk of adverse effects such as a deterioration in the storage stability and cosmetic durability of the cosmetic. The present invention has been made in view of the above-mentioned problems, and aims to provide a method for producing an oil dispersion that can obtain an oil dispersion with excellent dispersibility of inorganic oxide powder without the need to previously subject the inorganic oxide powder to surface treatment to enhance its dispersibility in oil agents and without the addition of a dispersant, and a cosmetic containing the oil dispersion produced by this production method. [Means for solving the problem]

[0007] As a result of intensive research to achieve the above object, 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 hydrocarbon oil containing at least one compound selected from ester oil, organic titanate compound, homopolymer of hydroxy fatty acid, and lecithin derivative as a treatment agent while heating at a temperature of 70 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 hydrocarbon oil (component (B)), and at least one compound (component (C)) selected from ester oil, organic titanate compound, homopolymer of hydroxy fatty acid, and lecithin derivative.

[0008] A method for producing an oil-based dispersion according to one embodiment of the present invention is characterized by comprising the steps of: (1) gradually adding inorganic oxide powder to a hydrocarbon oil containing at least one compound selected from ester oil, organic titanate compound, homopolymer of hydroxy fatty acid, and lecithin derivative as a processing agent while heating the hydrocarbon oil at a temperature of 70°C to 120°C; and (2) further mixing the dispersion to which the entire amount of inorganic oxide powder has been added at a temperature of 70°C to 120°C.

[0009] In the method for producing the oily dispersion of the present invention, a kneading mixer or a wet mixer disperser is preferably used for dispersion in step (2) of the above-mentioned production method. One embodiment of the method for producing an oil-based dispersion of the present invention is a method for producing an oil-based dispersion, which comprises step (1) of adding inorganic oxide powder to a hydrocarbon oil containing at least one compound selected from ester oil, organic titanate compounds, homopolymers of hydroxy fatty acids, and lecithin derivatives as a processing agent while heating the hydrocarbon oil at a temperature of 70°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 70°C to 120°C, followed by cooling the oil-based dispersion and further dispersing it using a wet mixer / disperser.

[0010] In the method for producing the oil dispersion of the present invention, after step (2) of the above production method, the oil dispersion is preferably cooled to room temperature (20°C to 30°C) and further dispersed using a wet mixer / disperser. In the above aspect, the solid content concentration of the inorganic oxide powder during production of the oily dispersion is preferably 25% by mass or more.

[0011] According to the present invention, the oil dispersion contains an inorganic oxide powder (component (A)) that has not been hydrophobized, a hydrocarbon oil (component (B)), and at least one compound (component (C)) selected from ester oils, organic titanate compounds, homopolymers of hydroxy fatty acids, and lecithin derivatives, 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 with no observed aggregation, and cases in which the dispersed particles in the oil dispersion are nearly uniform with slight observed aggregation. 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.

[0012] 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. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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 procedures are carried out under the conditions of room temperature (20°C to 30°C) and a relative humidity of 45 to 55% RH.

[0014] The method for producing the oil-based dispersion of the present invention comprises mixing the following components (A) to (C): (A) Inorganic oxide powder that has not been hydrophobized (B) Hydrocarbon oil (C) at least one compound selected from ester oils, organic titanate compounds, homopolymers of hydroxy fatty acids, and lecithin derivatives 1. A method for producing an oil dispersion comprising: A step (1) of adding component (A) to an oil solution in which component (C) is dissolved or dispersed in component (B) while heating the oil solution at a temperature of 70°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 70°C to 120°C.

[0015] According to the present invention, an oil-based dispersion with high powder dispersibility can be obtained by gradually adding non-hydrophobized inorganic oxide powder to a hydrocarbon oil solution containing at least one compound selected from ester oil, organic titanate compound, homopolymer of hydroxy fatty acid, and lecithin derivative as a treatment agent while heating at a temperature of 70°C to 120°C, and further, a cosmetic containing the oil-based dispersion can be obtained.

[0016] The inorganic oxide powder that is component (A) of the present invention and that has not been hydrophobized includes inorganic oxides commonly used in cosmetics, such as silicic anhydride (silicon oxide), aluminum oxide, iron oxide (e.g., red iron oxide, yellow iron oxide, black iron oxide), titanium oxide, zinc oxide, cerium oxide, and bismuth oxide. For the purpose of 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 these 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. 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.

[0017] The solids concentration of the inorganic oxide powder, which is component (A) of the present invention, is preferably 25% by mass or more, and more preferably 40 to 80% by mass. If the solids concentration of the inorganic oxide powder is less than 25% by mass, an oil-based dispersion in which the inorganic oxide powder remains well dispersible over time may not be obtained, while if it exceeds 80% by mass, the powder may aggregate, making it impossible to obtain a dispersion at all.

[0018] In the present invention, the hydrocarbon oil of component (B) used as a dispersion medium is a medium for dispersing component (A) and may be in any form, such as solid oil, semi-solid oil, or liquid oil, but a liquid oil that is liquid at room temperature is preferred from the viewpoint of the dispersibility of component (A). Examples of such a liquid oil include liquid paraffin, squalane, vegetable squalane, petrolatum, polyisobutylene, and polybutene.

[0019] In the present invention, component (C) is at least one compound selected from the group consisting of ester oils, organic titanate compounds, homopolymers of hydroxy fatty acids, and lecithin derivatives, used as a treatment agent.

[0020] The ester oil of component (C) of the present invention is an ester oil having 8 to 22 carbon atoms in the portion derived from a fatty acid, and examples thereof include isononyl isononanoate, isodecyl isononanoate, isotridecyl isononanoate, tricyclodecanemethyl isononanoate, coconut (caprylate / caprate), hexyl laurate, methylheptyl laurate, caprylyl laurate, decyl laurate, isopropyl myristate, methylheptyl myristate, 2-hexyldecyl myristate, octyldodecyl myristate, and iso palmitate. Monoesters such as propyl, methylheptyl palmitate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, ethyl isostearate, isopropyl isostearate, isobutyl isostearate, decyl isostearate, methylheptyl isostearate, 2-hexyldecyl isostearate, 2-ethylhexyl hydroxystearate, octyldodecyl oleate, oleyl oleate, octyldodecyl ricinoleate, octyl p-methoxycinnamate, alkyl benzoate, and glyceryl isostearate. Sterile Oil; Dicaprylic / Capric Dipropanediol, Neopentyl Glycol Diisononanoate, Neopentyl Glycol Dicaprate, Propylene Glycol Dicaprate, Glyceryl Diisostearate, Polyglyceryl Diisostearate, Propanediol Diisostearate, Phytosteryl / Octyldodecyl Lauroyl Glutamate, Cholesteryl / Behenyl / Octyldodecyl Lauroyl Glutamate, Phytosteryl / Behenyl / Octyldodecyl Lauroyl Glutamate, Dioctyldodecyl Dioctanoate diester oils such as dipentyl glycol; triester oils such as trimethylolpropane triisostearate, diglyceryl triisostearate, diglyceryl triisostearate, caprylic / capric triglyceride, glyceryl trioctanoate, macadamia nut oil, olive oil, castor oil, jojoba oil, avocado oil, and sunflower oil; pentaerythrityl tetraoctanoate, diglyceryl tetraisostearate, dipentaerythrityl tetraisostearate, and pentaerythrityl tetraisostearate.

[0021] The organic titanate compound, component (C) of the present invention, is preferably a long-chain carboxylic acid type having an alkyl group having 8 to 24 carbon atoms. Specific examples of alkyl titanates include isopropyl triisostearoyl titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, and diisostearoyl ethylene titanate.

[0022] The hydroxy fatty acid homopolymer, component (C) of the present invention, is a polymer (homopolymer) formed solely from hydroxy fatty acids, without copolymerization with any other component. Here, the hydroxy fatty acid is a fatty acid in which at least one hydrogen atom has been substituted with a hydroxy group, and may be either linear or branched. The number of carbon atoms in the fatty acid of the hydroxy fatty acid is preferably 12 to 20. Having a fatty acid with a carbon number of 12 to 20 can improve the dispersibility of component (A) in an oil-based dispersion. Examples of fatty acids in such hydroxy fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid. A preferred hydroxy fatty acid is hydroxystearic acid, and a preferred hydroxy fatty acid homopolymer is polyhydroxystearic acid.

[0023] The lecithin derivative, component (C) of the present invention, is a "hydrogenated lecithin," a compound obtained by adding hydrogen to lecithin, whose main component is phospholipid, a major component of biological membranes. Lecithin is broadly divided into "egg yolk lecithin" made from egg yolk and "soybean lecithin" made from soybeans, and examples thereof include hydrogenated soybean lecithin obtained by adding hydrogen to soybean lecithin.

[0024] The amount of component (C) in the oil dispersion of the present invention is preferably in the range of 1% by mass to 10% by mass relative to the concentration of the inorganic oxide powder. If the amount is less than 1% by mass, the inorganic oxide powder may not be uniformly dispersed in the hydrocarbon oil, while if it exceeds 10% 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.

[0025] The method for producing the oily dispersion of the present invention is a production method that is carried out in the following order: Step (1) and Step (2).

[0026] process(1); In step (1), a hydrocarbon oil containing at least one compound selected from ester oil, organic titanate compound, homopolymer of hydroxy fatty acid, and lecithin derivative is heated at a temperature of 70° C. to 120° C. while adding inorganic oxide powder to the hydrocarbon oil until the desired amount is added. It is preferable to gradually add the inorganic oxide powder to the hydrocarbon oil. The temperature of the hydrocarbon oil is preferably maintained within the above temperature range while the inorganic oxide powder is being added. It is preferable to heat the hydrocarbon oil using an appropriate heating means so that the temperature is maintained within the above temperature range. The time for adding the inorganic oxide powder to the hydrocarbon oil is, for example, 1 minute to 100 minutes. The dispersion method for obtaining the oil dispersion in step (1) includes a method in which the inorganic oxide powder is added while stirring the hydrocarbon oil 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.

[0027] Process (2); The oil dispersion obtained in step (1) is further mixed at a temperature of 70°C to 120°C to obtain an oil-based dispersion. The dispersion time in step (2) is preferably 2 hours or more from the viewpoint of dispersibility of the inorganic oxide powder in the hydrocarbon oil, 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. However, it is preferable to use a wet mixer / disperser capable of applying a higher shear force, such as a kneader mixer, Henschel mixer, roll mixer, or extruder mixer, or 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.

[0028] In the steps (1) and (2), the temperature conditions during production are preferably such that the hydrocarbon oil and oil dispersion are heated to a temperature of 70° C. to 120° C. Temperatures below 70° C. are not preferred because the inorganic oxide powder cannot be uniformly dispersed in the hydrocarbon oil, while temperatures above 120° C. are not preferred because yellow iron oxide and black iron oxide in the inorganic oxide powder may discolor.

[0029] After steps (1) and (2), it is preferable to cool the oil dispersion and 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 to 40°C or below, and preferably to room temperature (20°C to 30°C). Examples of cooling methods include a method in which the mixture is left standing while stirring, and a method in which the oil dispersion is cooled using a cooling means while stirring. From the viewpoint of improving the dispersibility of the inorganic oxide powder in the oil dispersion, a wet mixer disperser is preferred, 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.

[0030] Next, the cosmetic of the present invention will be described. The cosmetic of the present invention uses a highly safe hydrocarbon oil by blending the oil dispersion prepared by the above-mentioned production method, and therefore can be made into a cosmetic such as a sunscreen that is compatible with other cosmetic ingredients, has good stability over time despite a high solids concentration, and has a high SPF value and transparency. Specific examples of the cosmetic include makeup cosmetics such as foundation, eye shadow, and blush, sunscreen cosmetics, hair cosmetics, emulsions, creams, and other basic cosmetics. The amount of the oil dispersion blended is not particularly limited, but is preferably 0.1 to 90% by mass in the cosmetic.

[0031] 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.

[0032] The cosmetic composition of the present invention may be in the form of a powder, emulsion, cream, stick, or solid. Any dosage form such as a mold, spray, or multi-layer separation type may be used. [Example]

[0033] 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 containing this oil dispersion, but the present invention is not limited to the following examples.

[0034] Example 1 1.2 g of caprylic / capric triglyceride and 38.8 g of squalane were mixed and heated to 90°C. After confirming that the temperature had reached 90°C, 60 g of titanium oxide (MP-1133, manufactured by Teika Corporation) was added little by little over 10 minutes while stirring with a disperser at 2000 rpm. After the entire amount of titanium oxide was added, the mixture was further stirred at 90°C and 2000 rpm for an additional 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0035] Example 2 An oil dispersion of red iron oxide with a solid content concentration of 60 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.

[0036] Example 3 An oil dispersion of yellow iron oxide with a solid content concentration of 60 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.

[0037] Example 4 An oily dispersion of black iron oxide with a solid content concentration of 60 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.

[0038] 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) at 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 of 60 mass%. The obtained oil dispersion showed good dispersibility and storage stability at high temperatures.

[0039] Example 6 4 g of polyhydroxystearic acid and 46 g of squalane were mixed and heated to 70°C. After confirming that the temperature had reached 70°C, 50 g of titanium dioxide microparticles (MT-100SA, manufactured by Teika Corporation) were gradually added over 9 minutes while stirring at 2000 rpm with a disperser. After the entire amount of titanium dioxide microparticles was added, it was dispersed for 2 hours using a wet bead mill (DYNO-MILL, manufactured by Shinmaru Enterprises) at a peripheral speed of 10 m / s, φ0.5 mm zirconia beads, a filling rate of 70%, and a temperature of 70°C, yielding an oil-based dispersion of titanium dioxide microparticles with a solids concentration of 50% by mass. The resulting oil-based dispersion exhibited good dispersibility and storage stability at high temperatures.

[0040] Example 7 1.2 g of polyhydroxystearic acid and 38.8 g of squalane were mixed and heated to 110°C. After confirming that the temperature had reached 80°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 with a disper. After the entire amount of titanium oxide was added, the mixture was stirred at 110°C for an additional 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0041] Example 8 1.2 g of isopropyl triisostearoyl titanate (Plenact KR-TTS, manufactured by Ajinomoto Fine-Techno Co., Inc.) and 38.8 g of liquid paraffin were mixed and heated to 100°C. After confirming that the temperature had reached 100°C, 60 g of titanium oxide (MP-1133, manufactured by Teika Corporation) was added little by little over 10 minutes while stirring with a disper at 2000 rpm. After the entire amount of titanium oxide was added, the mixture was stirred at 100°C for an additional 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0042] Example 9 An oily dispersion of titanium oxide with a solid content concentration of 60 mass % was obtained in the same manner as in Example 8, except that the heating temperature was changed to 120°C.

[0043] Example 10 2.0 g of 2-ethylhexyl palmitate and 58.0 g of liquid paraffin were mixed and heated to 80°C. After confirming that the temperature had reached 80°C, 40 g of finely divided zinc oxide particles (MZ-500, manufactured by Teika Corporation) were added little by little over 8 minutes while stirring with a disper at 2000 rpm. After the entire amount of finely divided zinc oxide was added, the mixture was stirred at 80°C for an additional 3 hours, yielding an oil-based dispersion of finely divided zinc oxide particles with a solids concentration of 40% by mass.

[0044] Example 11 1.4 g of polyhydroxystearin and 28.6 g of liquid paraffin were heated to 90°C. After confirming that the temperature had reached 90°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 with a disper at 2000 rpm. After the entire amount of zinc oxide was added, the mixture was stirred at 90°C for an additional 3 hours, yielding an oil-based dispersion of zinc oxide with a solids concentration of 70% by mass.

[0045] Example 12 An oily dispersion of titanium oxide with a solid content concentration of 60% by mass was obtained in the same manner as in Example 1, except that hydrogenated lecithin (NIKKOL Resinol S-10, manufactured by Nikko Chemicals) was used instead of caprylic / capric triglyceride.

[0046] (Comparative Example 1) An oily dispersion of titanium oxide with a solid content concentration of 60 mass % was obtained in the same manner as in Example 1, except that the temperature was changed from 90°C to 60°C.

[0047] (Comparative Example 2) Without using any treatment agent, 40 g of squalane was heated to 90°C. After confirming that the temperature had reached 90°C, 60 g of titanium oxide (MP-1133, manufactured by Teika Corporation) was added little by little over 10 minutes while stirring with a disper at 2000 rpm. After the entire amount of titanium oxide was added, the mixture was stirred at 90°C for an additional 3 hours, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0048] (Comparative Example 3) Without using any treating agent, 40 g of squalane was heated to 90°C. After confirming that the temperature had reached 90°C, 60 g of titanium oxide (OTS-2 CR-50, manufactured by Daito Kasei Kogyo Co., Ltd.) surface-treated with octyltriethoxysilane was gradually added over 10 minutes while stirring with a disperser at 2000 rpm. After the entire amount of surface-treated titanium oxide was added, the mixture was further stirred at 90°C for 3 hours to obtain an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass.

[0049] Next, the method for evaluating dispersion stability used in the examples will be described. The redispersibility of the sample was visually observed one day after preparation and the sample stored at 40°C for one month (if particles have settled, shake well). Evaluation criteria after 1 day ○: The dispersed particles were uniform and no aggregation was observed. △: Dispersed particles were almost uniform, but slight aggregation was observed. ×: Dispersed particles were not uniform and significant aggregation was observed. Evaluation criteria after 1 month storage ○: The dispersed particles were uniform and no aggregation was observed. △: Dispersed particles were almost uniform, but slight aggregation was observed. ×: The particles were not redispersed, and sedimentation or significant aggregation was observed.

[0050] The results of evaluation of Examples 1 to 12 and Comparative Examples 1 to 3 by the above evaluation methods are shown in Table 1.

[0051] [Table 1]

[0052] The products of the present invention, Examples 1 to 12, showed good dispersibility one day after production and after storage at 40°C for one month. It was also found that the products of the present invention were superior in dispersibility, particularly in dispersibility over time, compared to 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).

[0053] Example 13: 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 Example 13 was good.

[0054] [Table 2]

[0055] Example 14: Sunscreen cream A sunscreen cream was obtained using the formulation shown in Table 3 and the following manufacturing method. The dispersion stability of Example 14 was good.

[0056] [Table 3]

[0057] (Manufacturing method) Components (1) to (5) were mixed together, and an aqueous solution of components (6) to (9), which had been mixed and dissolved in advance, was added to the mixture while stirring with a homomixer to obtain the desired water-in-oil sunscreen cream.

[0058] The cosmetics of Examples 13 and 14 had good pigment dispersion stability. [Industrial Applicability]

[0059] The oil dispersion produced by the production method of the present invention is characterized by high dispersibility of inorganic oxide powders that tend to aggregate in oil agents. Furthermore, this oil dispersion can provide cosmetics with good dispersion stability, and has great industrial applicability.

Claims

1. The following components (A) to (C): (A) Inorganic oxide powder that has not been hydrophobized (B) Hydrocarbon oil (C) At least one compound selected from ester oils, organic titanate compounds, homopolymers of hydroxy fatty acids, and lecithin derivatives 1. A method for producing an oil dispersion comprising: A step (1) of adding component (A) to an oil solution in which component (C) is dissolved or dispersed in component (B) while heating the oil solution at a temperature of 70°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 70°C to 120°C.

2. The method for producing an oil-based dispersion according to claim 1, wherein the solids concentration of component (A) in the oil-based 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 the step (2).

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

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

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

7. A cosmetic preparation containing the oily dispersion produced by the production method according to claim 3.

8. A cosmetic preparation containing the oily dispersion produced by the production method according to claim 4.

9. A cosmetic preparation containing the oily dispersion produced by the production method according to claim 5.

10. (A) Inorganic oxide powder that has not been hydrophobized (B) Hydrocarbon oil (C) At least one compound selected from ester oils, organic titanate compounds, homopolymers of hydroxy fatty acids, and lecithin derivatives wherein component (A) is uniformly or substantially uniformly dispersed at a solids concentration of 25% by mass or more.

11. The oil dispersion according to 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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