JP-7855198-B2 - Surface treatment method for pigment powders

Inventors

• 長谷 昇
• 秦 萌

Assignees

• 日光ケミカルズ株式会社

Dates

Publication Date

20260508

Application Date

20221102

Claims (2)

1. A method for producing a surface-treated powder in which the surface of a pigment powder is treated with at least one water-poorly soluble compound selected from the group consisting of ceramides, higher fatty acids, higher alcohols, alkyl glyceryl ethers, fatty acid esters, propylene glycol fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, lecithin derivatives, and alkyl phosphoric acid, wherein the manufacturing process includes a step of mixing the water-poorly soluble compound and the pigment powder to make a powder mixture, a step of adding 20 % to 30% by mass of water to the powder mixture to make a powder-water mixture, and further heating and aging to evaporate and remove the water.
2. The surface treatment method for pigment powder according to claim 1, characterized in that the amount of the water-poorly soluble compound coating the pigment powder is 0.1 to 10% by mass.

Description

This invention relates to a method for surface-treating the surface of pigment powder with a solid compound that is poorly soluble in water, and more particularly to a method for surface-treating pigment powder used in makeup cosmetics such as foundation, eyeshadow, blush, or sunscreen cosmetics. Conventionally, methods for surface-treating solid compounds that are poorly soluble in water include: 1) a mechanochemical method in which the compound and pigment powder are directly mixed using a machine such as a ball mill or sand mill, and then the surface treatment is performed; or 2) a method in which the compound to be used as a surface treatment agent is dissolved or suspended in a suitable solvent, mixed with the pigment powder, and then the solvent is removed and pulverization is performed as necessary (see Patent Documents 1 and 2). However, in the above treatment method 1), due to its mechanochemical nature, it is difficult to uniformly treat the pigment surface with the compound. In the above treatment method 2), when using compounds that are poorly soluble in solvents, uniform treatment is difficult, and there is also the problem that it is not possible to treat more than a certain amount of pigment powder. Another known surface treatment method involves dispersing pigment powder in water, adding a solid compound that is sparingly soluble in water and a metal salt that is soluble in water, and then adsorbing the metal salt of the compound onto the powder surface (see Patent Documents 3 and 4). However, this method had problems due to the complexity of the process, which involved dispersing the pigment powder in water, followed by cumbersome steps such as filtration, and the need to convert the compound into a metal salt. Japanese Patent Publication No. 2001-181136Japanese Patent Publication No. 2007-238690Japanese Patent Application Publication No. 184571/1983Japanese Patent Application Publication No. 1987-190705 Next, a specific embodiment of the surface treatment method for pigment powders according to the present invention will be described. The present invention relates to a surface treatment method for pigment powders, which involves mixing a water-insoluble compound that is solid at room temperature and has ester bonds and/or hydroxyl groups in its molecular structure with the pigment powder to form a powder mixture. Then, water in an amount of 0.1% to 30% by mass relative to the pigment powder is added to the powder mixture to form a powder-water mixture. The mixture is then heated and aged to evaporate and remove the water, and in some cases, the mixture is pulverized to perform the surface treatment. Furthermore, the method for evaporating and removing the water is not particularly limited as long as the water can be removed, but it generally involves drying at a high temperature (70-120°C) for several hours. For mixing and dispersing the pigment powder, the water-insoluble compound, and water, a reaction vessel with stirring blades, a disperser, a Henschel mixer, a Redigge mixer, a kneader, a V-type mixer, a roll mill, etc., can be selected. Furthermore, when grinding is performed, conventional grinders such as hammer mills, ball mills, sand mills, and jet mills can be used. Since equivalent quality can be obtained with any of these grinders, there is no particular limitation. The amount of aqueous solvent used in this invention is preferably between 0.1% by mass and 30% by mass relative to the powder mixture. If the amount exceeds 30% by mass, the powder mixture will agglomerate, making it difficult to obtain a sufficiently mixed powder-water mixture. Furthermore, the time required for the water to dry completely will be long, reducing productivity. The minimum required amount of aqueous solvent is 0.1% by mass relative to the powder mixture. Amounts less than 0.1% by mass are undesirable because the surface treatment effect of the water-insoluble compound cannot be obtained. In this invention, examples of water-insoluble compounds that are solid at room temperature and have ester bonds and/or hydroxyl groups in their molecular structure, which are surface-treated onto pigment powders, include ceramides, higher fatty acids, higher alcohols, alkyl glyceryl ethers, fatty acid esters, propylene glycol fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, lecithin derivatives, alkyl phosphates, and the like. The water-insoluble ceramide compounds according to the present invention can be one or more selected from natural-type ceramides and pseudo-type ceramides. Specifically, the ceramides described in Japanese Patent Application Publication No. 2013-53146 can be used. Examples of commercially available natural-type ceramides include Ceramide I, Ceramide III, Ceramide IIIA, Ceramide IIIB, Ceramide IIIC, Ceramide VI (all manufactured by Cosmo Farm Co., Ltd.), Ceramide TIC-001 (manufactured by Takasago International Corporation), CERAMIDE II