Method for producing oily dispersion and cosmetic containing said oily dispersion

Abstract

The present invention addresses the problem of providing: a method for producing an oily dispersion in which an inorganic oxide powder has excellent dispersibility without the need to previously subject the inorganic oxide powder to a surface treatment in order to improve the dispersibility in silicone oils; and a cosmetic containing this oily dispersion. This method is for producing an oily dispersion comprising the following components (A) to (C), and is characterized in that the production process therefore includes a step (1) in which the component (A) is slowly added to a mixture oil while heating the mixture oil at a temperature of 40-120°C, the mixture oil being one obtained by dissolving or dispersing the component (C) in the component (B), and a step (2) in which a dispersion obtained by adding the whole amount of the component (A) is further mixed at a temperature of 40-120°C. (A) An inorganic oxide powder having undergone no hydrophobization treatment, (B) a silicone oil, and (C) at least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organic titanate compounds, and higher fatty acids.

Description

Method for producing oily dispersion and cosmetic containing the oily dispersion

[0001] The present invention relates to a method for producing an oil dispersion and a cosmetic containing the oil dispersion. More specifically, the present invention relates to a method for producing an oil dispersion that is dispersible in an oil agent despite having a high solid content by adding an inorganic oxide powder to a silicone oil containing at least one compound selected from a silicone compound, an organosilicon compound, an organotitanate compound, and a higher fatty acid at a specific temperature, and to a cosmetic containing the oil dispersion produced by this production method.

[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 an oil agent as they are. Therefore, inorganic oxide powders used in oil dispersions are widely subjected to hydrophobic treatment in order to facilitate dispersion of the inorganic oxide powder in an oil agent. For example, a method is known in which the pigment surface is coated with a silicone such as a higher fatty acid, a higher alcohol, a hydrocarbon, a silicone oil, or a silicone resin to impart hydrophobicity. Among these, many methods for hydrophobic treatment of 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, 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, Patent Documents 6 and 7).

[0005] Japanese Patent Laid-Open No. 60-163973 Japanese Patent Laid-Open No. 62-177070 Japanese Patent Laid-Open No. 2002-80748 Japanese Patent Laid-Open No. 2005-171145 Republished No. 2011 / 007668 Japanese Patent Laid-Open No. 2007-291379 Japanese Patent Laid-Open No. 2012-184178

[0006] However, in the method of hydrophobizing inorganic oxide powder, an oil-based dispersion cannot be produced 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.

[0007] 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.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a production method by which an oily dispersion of inorganic oxide powder with excellent dispersibility can be obtained without the need for prior surface treatment to enhance the dispersibility of the inorganic oxide powder in an oil agent and without the addition of a dispersant, and a cosmetic containing the oily dispersion produced by this production method.

[0009] As a result of intensive research conducted by the present inventors to achieve the above object, they discovered that by adding an inorganic oxide powder that has not been hydrophobized to a silicone oil containing at least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organotitanate compounds, and higher fatty acids as a treatment agent while heating the mixture at a temperature of 40°C to 120°C, an oil-based dispersion with high pigment dispersibility can be obtained, and further, high pigment dispersibility can be maintained without the use of a dispersant, thereby completing the present invention.

[0010] A method for producing an oil-based dispersion according to one embodiment of the present invention is characterized by comprising the steps of: (1) adding inorganic oxide powder to a silicone oil containing at least one compound selected from a silicone compound, an organosilicon compound, an organotitanate compound, and a higher fatty acid while heating the silicone oil at a temperature of 40°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 40°C to 120°C.

[0011] In the method for producing the oily 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 above-mentioned production method.

[0012] One embodiment of 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), comprising the steps of: step (1) of adding component (A) to a mixture obtained by dissolving or dispersing component (C) in component (B) while heating the mixture at a temperature of 40 to 120°C; and step (2) of further mixing the dispersion to which the entire amount of component (A) has been added at a temperature of 40 to 120°C, wherein the oil dispersion is cooled after all steps of the production method have been completed, and further dispersed using a wet mixer / disperser: (A) inorganic oxide powder that has not been hydrophobized; (B) silicone oil; and (C) at least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organotitanate compounds, and higher fatty acids.

[0013] In 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.

[0014] Furthermore, the cosmetic of the present invention is characterized by containing the oily dispersion produced by the production method of the present invention.

[0015] Next, specific embodiments of the method for producing an oily dispersion according to the present invention and 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, operations are carried out under conditions of room temperature (20°C to 30°C) and a relative humidity of 45 to 55% RH. It should be understood that all combinations of the embodiments are disclosed in this application.

[0016] The method for producing an oil-based dispersion of the present invention is a method for producing an oil-based dispersion containing the following components (A) to (C): (A) inorganic oxide powder that has not been hydrophobized, (B) silicone oil, and (C) at least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organotitanate compounds, and higher fatty acids, the method comprising the steps of: (1) adding component (A) to a mixture obtained by dissolving or dispersing component (C) in component (B) while heating the mixture 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.

[0017] According to the present invention, an oil-based dispersion can be obtained that has high pigment dispersibility and can maintain high dispersibility over time (even without using a dispersant), and further, a cosmetic preparation containing the same can be obtained.

[0018] (Component (A): Non-hydrophobized inorganic oxide powder) Examples of the non-hydrophobized inorganic oxide powder, which is component (A) of the present invention, 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 ultraviolet screening effect, 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 types. Furthermore, one type may be used alone, or two or more types may be used in combination.

[0019] The inorganic oxide powder in component (A) is used without being subjected to a hydrophobic treatment. Here, "hydrophobic treatment" refers to treatment with a known hydrophobic surface treatment agent such as a silicone treatment or a fatty acid treatment. Furthermore, the inorganic oxide powder is preferably an untreated powder. "Untreated powder" refers to powder that has not been surface-treated with a surface treatment agent. In one embodiment, component (A) is at least one selected from the group consisting of untreated iron oxide, untreated titanium oxide, and untreated zinc oxide.

[0020] The particle size of the inorganic oxide powder is, for example, 0.001 to 50 μm, and may be 0.01 to 30 μm. The particle size is based on volume and can be measured using a laser diffraction particle size distribution analyzer.

[0021] The solids concentration in the oil dispersion of the inorganic oxide powder, which is component (A) of the present invention (the content ratio of component (A) to the solids in the oil dispersion) is preferably 25% by mass or more, more preferably 25 to 80% by mass, and even more preferably 30 to 80% by mass. When the solids concentration in the oil dispersion of the inorganic oxide powder is 25% by mass or more, the dispersibility of the inorganic oxide powder becomes good over time, and when it is 80% by mass or less, aggregation of the powder is easily suppressed.

[0022] (Component (B): Silicone Oil) Component (B) is a silicone oil. Here, the silicone oil of component (B) is used as a dispersion medium. By using silicone oil as a dispersion medium, the dispersibility of the inorganic oxide powder is significantly improved. Here, when multiple silicone oils are used in producing the oil-based dispersion, the silicone oil of component (B) that is added in the largest amount is designated as component (B). When there are multiple silicone oils with the largest content, all of the silicone oils are designated as component (B). Specifically, the silicone oil of component (B) is preferably a silicone oil in an amount exceeding 50% by mass relative to the total amount of components (B) and (C).

[0023] In the present invention, the silicone oil of component (B) used as a dispersion medium includes alkyl-modified silicones such as dimethylpolysiloxane (dimethicone), methylphenylpolysiloxane, diphenylpolysiloxane (diphenyldimethicone), diphenylsiloxyphenyltrimethicone, caprylylmethicone, methyltrimethicone, cyclopentasiloxanemethyltrimethicone, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, etc. The silicone oil of component (B) is preferably at least one selected from the group consisting of dimethylpolysiloxane (dimethicone), diphenylsiloxyphenyltrimethicone, decamethylcyclopentasiloxane, and methylphenylpolysiloxane, and more preferably at least one selected from the group consisting of dimethylpolysiloxane (dimethicone), diphenylsiloxyphenyltrimethicone, and decamethylcyclopentasiloxane.

[0024] The silicone oil of component (B) may be either volatile or nonvolatile. The viscosity of the silicone oil of component (B) at 25°C is preferably 50 mPa s or less (lower limit: 1 mPa s or more), and may be 20 mPa s or less. When the viscosity of the silicone oil is 50 mPa s or less, the viscosity of the dispersion becomes appropriate.

[0025] In terms of the effects of the present invention, the content of component (B) in the oil dispersion is preferably 25% by mass or more, more preferably 25 to 80% by mass, and even more preferably 25 to 70% by mass.

[0026] (Component (C): At least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organic titanate compounds, and higher fatty acids) Component (C) of the present invention is at least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organic titanate compounds, and higher fatty acids. Component (C) is used as a treatment agent. By adding inorganic powder while heating it in a state where component (C) is dissolved and dispersed in component (B), the dispersibility of the inorganic powder is improved and good dispersibility is maintained. Here, component (C) does not include component (B).

[0027] The silicone compound serving as component (C) of the present invention is not particularly limited as long as it can be used in cosmetics, and examples thereof include methylhydrogenpolysiloxane, amino-modified silicone, polyether-modified silicone, polyglycerin-modified silicone, carboxylic acid-modified silicone, alkyl-modified and polyether-modified silicone, alkyl-modified and polyglycerin-modified silicone (e.g., lauryl polyglyceryl-3 polydimethylsiloxyethyl dimethicone), pyrrolidone carboxylic acid-modified silicone, triethoxysilylethyl polydimethylsiloxyethyl dimethicone, triethoxysilylethyl polydimethylsiloxyethyl hexyl dimethicone, etc. Note that although some of the above are included in the category of silicone oil, as mentioned above, the silicone oil of component (B) refers to the silicone oil with the highest content, and is therefore distinguished from the silicone oil of component (C).

[0028] The silicone compound as component (C) is preferably liquid at room temperature (for example, 25°C). Here, liquid refers to a compound that has flowability at 25°C.

[0029] Examples of the organosilicon compound that is component (C) of the present invention include silylating agents and silane coupling agents into which an organic group has been introduced. Examples include alkoxysilanes such as tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, isobutyltrimethoxysilane, n-decyltrimethoxysilane, n-octyltrimethoxysilane, octyltriethoxysilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane; and silazanes such as dimethylpolysiloxysilazane.

[0030] The organic titanate compound, component (C) of the present invention, includes alkyl titanates such as long-chain carboxylic acid type, pyrophosphate type, phosphorous acid type, and amino acid type. Among these, the organic titanate compound 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 dimethacrylisostearoyl titanate, isopropyl isostearoyl diacryl titanate, and diisostearoyl ethylene titanate.

[0031] Examples of the higher fatty acid that is component (C) of the present invention include lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, palmitoleic acid, oleic acid, and linoleic acid. Of these, isostearic acid, palmitoleic acid, oleic acid, and linoleic acid, which are liquid at room temperature (e.g., 25°C), are preferred because they can reduce the viscosity of the oil dispersion.

[0032] Among these, component (C) is preferably at least one selected from the group consisting of methylhydrogenpolysiloxane, carboxylic acid-modified silicone, alkyl-modified and polyglycerin-modified silicone, pyrrolidonecarboxylic acid-modified silicone, amino-modified silicone, polyglycerin-modified silicone, alkoxysilane, isopropyl triisostearoyl titanate, and higher fatty acid.

[0033] The component (C) may be used alone or in combination of two or more types.

[0034] The amount of component (C) in the oil dispersion (the total amount when two or more types of component (C) are used) is preferably 1 to 15 mass % relative to component (A), and more preferably 2 to 10 mass %. When the amount of component (C) is at least the above lower limit, the inorganic oxide powder is easily dispersed uniformly in silicone oil, and when the amount is at most the above upper limit, the feel and stability of the cosmetic when the oil dispersion is incorporated into the cosmetic is likely to be good.

[0035] Furthermore, in terms of the effects of the present invention, the content of component (C) in the oil dispersion is preferably 0.5 to 10% by mass, and more preferably 1 to 8% by mass.

[0036] In addition, when two or more kinds of component (C) are used, the viscosity of the oil dispersion of the present invention can be reduced in some cases, and this is a preferred embodiment. For example, as component (C), a combination of a silicone compound and a higher fatty acid, a combination of an organosilicon compound and a higher fatty acid, or a combination of a silicone compound and an organosilicon compound are preferred embodiments.

[0037] (Other Components) The oil dispersion of the present invention preferably does not contain components other than components (A), (B), and (C) in a proportion of more than 20% by mass in the oil dispersion, but may contain other components in a proportion of 20% by mass or less relative to the oil dispersion, as long as the performance of the oil dispersion is not impaired, more preferably 10% by mass or less, and may be 5% by mass or less, 3% by mass or less, 1% by mass or less, or 0% by mass (the oil dispersion is composed of components (A), (B), and (C)). However, it is preferable not to add compounds that may impair the stability of the oil dispersion.

[0038] (Production Method) The method for producing the oil-based dispersion of the present invention is a production method that is carried out in the following order: Step (1) and Step (2).

[0039] Step (1): In step (1), a mixture (hereinafter simply referred to as the mixture) of at least one compound (component (C)) selected from the group consisting of silicone compounds, organosilicon compounds, organotitanate compounds, and higher fatty acids and silicone oil (component (B)) is heated at a temperature of 40°C to 120°C, while an inorganic oxide powder is added to the silicone oil until the desired amount is completely added.

[0040] The silicone oil of component (B) is a dispersion medium, and component (C) is dissolved or dispersed in component (B).

[0041] The mixture of component (B) and component (C) is heated to a predetermined temperature. The heating temperature is 40 to 120°C. If the heating temperature is below 40°C, pigment dispersibility will be significantly reduced. However, if a volatile silicone oil is used, it is preferable to heat the mixture at 60°C or below to prevent the silicone oil from volatilizing. Furthermore, if the heating temperature exceeds 120°C, yellow iron oxide and black iron oxide, among the inorganic oxide powders, will discolor, which is undesirable.

[0042] The temperature of the mixture is preferably maintained within the above temperature range while the inorganic oxide powder is being added. It is preferable to heat the mixture using an appropriate heating means so that the temperature is maintained within the above temperature range.

[0043] It is preferable to gradually add the inorganic oxide powder to the mixture, for example, over a period of 1 to 100 minutes.

[0044] 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 silicone oil phase (mixture) using a homomixer, disper, etc. 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.

[0045] In view of the effects of the present invention, it is preferable not to use a dispersant in step (1). Examples of dispersants include polyhydroxystearic acid, glyceryl hydroxystearate, polyglyceryl-2 diisostearate, polyglyceryl-2 triisostearate, polyglyceryl-2 tetraisostearate, erythrityl triethylhexanoate, and sorbitan sesquiisostearate.

[0046] 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 dispersion time in step (2) is preferably 2 hours or more from the viewpoint of dispersibility of the inorganic oxide powder in the silicone 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, but it is more 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, bead mill, sand mill, basket mill, or AD mill.

[0047] In view of the effects of the present invention, it is preferable not to use a dispersant in step (2) either.

[0048] In steps (1) and (2), the temperature conditions during production are preferably such that the mixture and dispersion are heated to a temperature of 40°C to 120°C. A temperature below 40°C is not preferred because the inorganic oxide powder cannot be uniformly dispersed in the silicone oil. However, when a volatile silicone oil is used, it is preferable to carry out the production at 60°C or less to prevent the silicone oil from volatilizing. Temperatures above 120°C are not preferred because yellow iron oxide and black iron oxide in the inorganic oxide powder may discolor. The heating temperature may be 40°C to 100°C.

[0049] After steps (1) and (2), it is preferable to add a cooling and dispersion step, since the inorganic oxide powder is further atomized and more uniformly dispersed in the oil agent. Cooling is preferably carried out until the temperature drops to 40°C or lower, 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 is continued, and a method in which the oil dispersion is cooled using a cooling means while stirring is continued.

[0050] The dispersing machine used for dispersing after cooling is preferably a wet mixer disperser, and among these, a wet bead mill is preferred, from the viewpoint of improving the dispersibility of the inorganic oxide powder in the oil dispersion. Specific examples of wet mixer dispersers are as described above. The dispersing time for dispersing after cooling is, for example, 15 minutes to 5 hours, and may be 30 minutes to 3 hours.

[0051] (Cosmetics) Next, the cosmetics of the present invention will be described. By incorporating the oily dispersion prepared by the above-described production method, the cosmetics of the present invention become cosmetics that feel good to the touch because they contain silicone oil that is pleasant to use. Moreover, despite having a high solids concentration, cosmetics such as sunscreens that have good stability over time and high SPF values ​​and transparency can be produced. Specific examples of cosmetics that can be used include makeup cosmetics such as foundations, eye shadows, and blushes, as well as basic cosmetics such as sunscreen cosmetics, hair cosmetics, emulsions, and creams. The amount of oily dispersion incorporated is not particularly limited, but is preferably 0.1 to 90% by mass in the cosmetics.

[0052] 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.

[0053] The cosmetic composition of the present invention may be in any form, such as powder, emulsion, cream, stick, solid, spray, or multi-layer separated type.

[0054] 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.

[0055] Example 1 1.2 g of alkyl-modified and polyglycerin-modified silicone (lauryl polyglyceryl-3 polydimethylsiloxyethyl dimethicone, KF-6105, manufactured by Shin-Etsu Chemical Co., Ltd.) and 38.8 g of dimethicone (KF-96A-6CS, 6 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) 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 Disper at 2000 rpm. After the entire amount of titanium oxide was added, the mixture was further stirred at 2000 rpm at 90°C for 3 hours to obtain an oil-based dispersion of titanium oxide (solids concentration of titanium oxide: 60% by mass).

[0056] Example 2 An oil dispersion of red iron oxide (solid content of red iron oxide: 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.

[0057] Example 3 An oil-based dispersion of yellow iron oxide (solid content concentration of yellow iron oxide: 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.

[0058] Example 4 An oil-based dispersion of black iron oxide (solid content of black iron oxide: 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.

[0059] (Example 5) The oil dispersion obtained in Example 1 was allowed to stand while stirring was continued to cool to room temperature (25°C), and further dispersed and mixed for 1 hour using a wet bead mill (DYNO-MILL, 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 (solid content concentration of titanium oxide: 60% by mass).

[0060] Example 6 4 g of isostearic acid (RADIACID0909, manufactured by Oleon) and 46 g of dimethicone (KF-96L-2CS, 2 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and heated to 60°C. After confirming that the temperature had reached 60°C, 50 g of titanium dioxide fine particles (MT-100SA, manufactured by Teika Corporation) was added little by little over 9 minutes while stirring with a disper at 2000 rpm. After the entire amount of titanium dioxide fine particles 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 60°C, to obtain an oil-based dispersion of titanium dioxide fine particles (solid concentration of titanium dioxide fine particles: 50% by mass).

[0061] Example 7 1.2 g of pyrrolidone carboxylic acid-modified silicone (Gransil PCA-C, manufactured by Grant Industries, Inc.) and 38.8 g of dimethicone (KF-96L-2CS, 2 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) 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 with a disper. After the entire amount of titanium oxide was added, the mixture was further stirred at a temperature of 60°C for 3 hours to obtain an oil-based dispersion of titanium oxide (solid content concentration of titanium oxide: 60% by mass).

[0062] Example 8 An oil-based dispersion of titanium oxide (solids concentration of titanium oxide: 60% by mass) was obtained in the same manner as in Example 7, except that a carboxylic acid-modified silicone (ES-5800, manufactured by Dow-Toray Industries, Inc.) was used instead of the pyrrolidone carboxylic acid-modified silicone.

[0063] Example 9 An oily dispersion of titanium oxide (solids concentration of titanium oxide: 60% by mass) was obtained in the same manner as in Example 7, except that amino-modified silicone (SF8452C, manufactured by Dow-Toray) was used instead of pyrrolidone carboxylic acid-modified silicone.

[0064] Example 10 2 g of octyltriethoxysilane (triethoxycaprylylsilane, AES-3083, manufactured by Shin-Etsu Chemical Co., Ltd.) and 58 g of decamethylcyclopentasiloxane (KF-995, 4 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and 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.) were added little by little over 8 minutes while stirring with a disper at 2000 rpm. After the entire amount of fine zinc oxide particles was added, the mixture was further stirred at a temperature of 50°C for 3 hours to obtain an oil-based dispersion of fine zinc oxide particles (solids concentration of fine zinc oxide particles: 40% by mass).

[0065] Example 11 1.4 g of octyltriethoxysilane (triethoxycaprylylsilane, AES-3083, manufactured by Shin-Etsu Chemical Co., Ltd.) and 28.6 g of decamethylcyclopentasiloxane (KF-995, 4 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and 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 with a disper at 2000 rpm. After the entire amount of zinc oxide was added, the mixture was further stirred at a temperature of 40°C for 3 hours, yielding an oil-based dispersion of zinc oxide (solids concentration of zinc oxide: 70% by mass).

[0066] Example 12 1.2 g of isopropyl triisostearoyl titanate (Plenact KR-TTS, manufactured by Ajinomoto Fine-Techno Co., Ltd.) and 38.8 g of diphenylsiloxyphenyl trimethicone (KF-56A, 15 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) 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 at 2000 rpm with a disper. After the entire amount of titanium oxide was added, the mixture was further stirred at a temperature of 90°C for 3 hours, and an oil-based dispersion of titanium oxide (solid content concentration of titanium oxide: 60% by mass) was obtained.

[0067] Example 13 An oil-based dispersion of titanium oxide (solids concentration of titanium oxide: 60% by mass) was obtained in the same manner as in Example 12, except that methylhydrogenpolysiloxane (KF-9901, manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of isopropyl triisostearoyl titanate.

[0068] Example 14 1.5 g of triethoxysilylethyl polydimethylsiloxyethyl dimethicone (KF-9908, manufactured by Shin-Etsu Chemical Co., Ltd.) and 68.5 g of dimethicone (KF-96A-6CS, 6 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and heated to 70°C. After confirming that the temperature had reached 70°C, 30 g of fine red iron oxide particles (TRR-100HP, manufactured by Titan Kogyo Co., Ltd.) was added little by little over 5 minutes while stirring with a disper at 2000 rpm. After the entire amount of fine red iron oxide particles was added, the mixture was further stirred at a temperature of 70°C for 3 hours to obtain an oil-based dispersion of fine red iron oxide particles (solids concentration of fine red iron oxide particles: 30% by mass).

[0069] Example 15 3 g of isostearic acid (RADIACID0909, manufactured by Oleon), 2 g of polyglycerin-modified silicone (polyglyceryl-3 polydimethylsiloxyethyl dimethicone, KF-6106, manufactured by Shin-Etsu Chemical Co., Ltd.), and 45 g of dimethicone (KF-96L-2CS, 2 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and heated to 60°C. After confirming that the temperature had reached 60°C, 50 g of titanium dioxide microparticles (MT-100SA, manufactured by Teika Co., Ltd.) was added little by little over 9 minutes while stirring with a disper at 2000 rpm. After the entire amount of titanium dioxide microparticles was added, the mixture was further stirred at a temperature of 60°C for 3 hours, and an oil-based dispersion of titanium dioxide microparticles (solids concentration of titanium dioxide microparticles: 50% by mass) was obtained.

[0070] Example 16 1.2 g of palmitic acid (NAA-160, manufactured by NOF Corporation) and 38.8 g of dimethicone (KF-96A-6CS, 6 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) 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 further stirred at a temperature of 100°C for 2 hours, and an oil-based dispersion of titanium oxide with a solid content concentration of 60% by mass (solid content concentration of titanium oxide: 60% by mass) was obtained.

[0071] Comparative Example 1 An oil dispersion of titanium oxide having a solid content of 60 mass % was obtained in the same manner as in Example 1, except that the temperature was changed from 90° C. to 30° C.

[0072] (Comparative Example 2) Without using a treatment agent, 40 g of dimethicone (KF-96A-6CS, 6 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) was heated to 90°C. After confirming that the temperature had reached 90°C, 60 g of titanium oxide (MP-1133, manufactured by Teika Co., Ltd.) was added little by little while stirring with a disper at 2000 rpm. After the entire amount of titanium oxide was added, stirring was continued for an additional 3 hours at a temperature of 90°C, yielding an oil-based dispersion of titanium oxide with a solids concentration of 60% by mass. (Comparative Example 3) Without using a treatment agent, 30 g of decamethylcyclopentasiloxane (KF-995, 4 mPa s, manufactured by Shin-Etsu Chemical Co., Ltd.) was heated to 40°C. After confirming that the temperature had reached 40°C, 70 g of titanium oxide surface-treated with octyltriethoxysilane (OTS-2 CR-50, manufactured by Daito Kasei Kogyo Co., Ltd.) was added little by little while stirring with a disper at 2000 rpm. After the entire amount of surface-treated titanium oxide was added, stirring was continued for an additional 3 hours at a temperature of 40°C, yielding an oil-based dispersion of titanium oxide with a solid content concentration of 70% by mass.

[0073] Comparative Example 4 An oily dispersion of titanium oxide having a solid content of 60% by mass was obtained in the same manner as in Example 1, except that squalane was used instead of dimethicone.

[0074] Next, the method for evaluating dispersion stability used in the examples will be described.

[0075] The redispersibility of the sample one day after preparation and the sample stored at 40°C for one month was visually observed (if particles had settled, the sample was shaken well).

[0076] 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.

[0077] 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.

[0078] The results of evaluation of Examples 1 to 16 and Comparative Examples 1 to 4 by the above evaluation methods are shown in Table 1.

[0079]

[0080] The products of the present invention, Examples 1 to 16, exhibited 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 4. It was also found that the oil-based 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).

[0081] Example 17 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 17 was good.

[0082]

[0083] (Example 18: Sunscreen cream) A sunscreen cream was obtained by the following manufacturing method using the formulation shown in Table 3. The dispersion stability of Example 18 was good (no aggregation or sedimentation of the powder occurred over time).

[0084]

[0085] (Production 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.

[0086] The cosmetics of Examples 17 and 18 had good pigment dispersion stability (no aggregation or settling of the powder occurred over time).

[0087] 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 silicone oil. Furthermore, this oil dispersion can provide cosmetics with good dispersion stability, and has great industrial applicability.

[0088] The present invention includes the following aspects.

[0089] 1. A method for producing an oil dispersion containing the following components (A) to (C), comprising the steps of: (1) adding component (A) to a mixture prepared by dissolving or dispersing component (C) in component (B) while heating the mixture 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: (A) inorganic oxide powder that has not been hydrophobized, (B) silicone oil, and (C) at least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organotitanate compounds, and higher fatty acids.

[0090] 2. The method for producing an oil-based dispersion according to 1., wherein the solids concentration of component (A) in the oil-based dispersion is 25% by mass or more.

[0091] 3. The method for producing an oil-based dispersion according to 1. or 2., wherein a kneading mixer or a wet mixer / disperser is used for mixing in step (2).

[0092] 4. The method for producing an oil-based dispersion according to any one of 1. to 3., wherein after step (2), the oil-based dispersion is cooled and further dispersed using a wet mixer / disperser.

[0093] 5. The method for producing an oil-based dispersion according to 3., wherein after all the steps of the production method according to 3. are completed, the oil-based dispersion is cooled and further dispersed using a wet mixer / disperser.

[0094] 6. A method for producing an oil-based dispersion according to any one of 1. to 5., wherein the oil-based dispersion consists solely of components (A) to (C).

[0095] 7. A cosmetic preparation containing an oily dispersion produced by the production method described in any one of 1. to 6.

[0096] This application is based on Japanese Patent Application No. 2023-091279, filed on June 2, 2023, the disclosure of which is hereby incorporated by reference in its entirety.

Claims

1. A method for producing an oil dispersion containing the following components (A) to (C), comprising the steps of: (1) adding component (A) to a mixture prepared by dissolving or dispersing component (C) in component (B) while heating the mixture 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: (A) inorganic oxide powder that has not been hydrophobized, (B) silicone oil, and (C) at least one compound selected from the group consisting of silicone compounds, organosilicon compounds, organotitanate compounds, and higher fatty acids.

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 mass% or more.

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

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. A method for producing the oil dispersion according to claim 3, comprising cooling the oil dispersion after all the steps of the method for producing the oil dispersion according to claim 3, and dispersing the oil dispersion using a wet mixer / disperser.

6. The method for producing the oil dispersion according to claim 1 or 2, which is an oil dispersion consisting of only the components (A) to (C).

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

8. A cosmetic preparation containing the oil dispersion produced by the method of claim 3.

9. A cosmetic preparation containing the oil dispersion produced by the method according to claim 4.

10. A cosmetic preparation containing the oil dispersion produced by the method of claim 5.

11. A cosmetic preparation containing the oil dispersion produced by the method according to claim 6.

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