Surface treatment method for pigment powders

Abstract

To provide a surface treatment method of pigment powder, which can adhere a slightly water-soluble compound uniformly to the pigment surface in a more amount than conventional methods.SOLUTION: The surface treatment method comprises the steps of: mixing a slightly water-soluble compound and pigment powder to obtain a powder mixture; and adding 0.1 mass% to 30 mass% of water to the powder mixture to obtain a powder-water mixture, followed further by heat-aging to remove water by evaporation. The surface treated powder obtained by this surface treatment method becomes surface-treated powder having high water repellency and being coated uniformly with a slightly water-soluble compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for surface-treating a solid compound that is poorly soluble in water on the surface of a pigment powder, and relates to a method for surface-treating a pigment powder incorporated in, for example, makeup cosmetics such as foundation, eyeshadow, and lipstick, or sunscreen cosmetics.

Background Art

[0002] Conventionally, as a method for surface-treating a solid compound that is poorly soluble in water, 1) a mechanochemical method in which the compound and the pigment powder are directly mixed using a machine such as a ball mill or a sand mill for surface treatment, or 2) a method in which the compound serving as a surface treatment agent is dissolved or suspended in an appropriate solvent, mixed with the pigment powder, and then the solvent is removed and pulverization is performed as necessary is known (see Patent Documents 1 and 2).

[0003] However, in the above treatment method 1), due to the mechanochemical treatment, it is difficult to uniformly treat the compound on the pigment surface. In the above treatment method 2), when a compound that is poorly soluble in the solvent is used, uniform treatment is difficult, and there is also a problem that the treatment cannot be performed on the pigment powder in an amount more than a certain level.

[0004] Also, as another surface treatment method, a method is known in which the pigment powder is dispersed in water, a solid compound that is poorly soluble in water and a metal salt that is soluble in water are added thereto, and the metal salt of the compound is adsorbed on the powder surface (see Patent Documents 3 and 4).

[0005] [[ID=二十三]] However, in this method, once the pigment powder is dispersed in water, there are problems in terms of complexity such as subsequent complicated procedures such as filtration and making the compound into a metal salt.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] This invention has been made in view of the aforementioned problems, and aims to provide a surface treatment method for pigment powders that can uniformly adhere solid compounds, which are poorly soluble in water, to the pigment surface, compared to conventional methods. [Means for solving the problem]

[0008] The inventors of the present invention have discovered that by thoroughly mixing a solid compound that is poorly soluble in water with a pigment powder to form a powder mixture, and then adding 0.1% to 30% by mass of water to the powder mixture to form a powder-water mixture, a more uniform coating treatment can be achieved than with conventional methods, and have completed the present invention.

[0009] In short, in order to achieve the above objective, the surface treatment method for pigment powder according to the present invention is characterized by comprising the steps of thoroughly 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, and adding 0.1% by mass or more and 30% by mass or less of water relative to the pigment powder to the powder mixture to form a powder-water mixture.

[0010] In the present invention, the water-insoluble compound is preferably at least one 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 phosphates. [Effects of the Invention]

[0011] According to the present invention's surface treatment method for pigment powders, a water-insoluble compound and pigment powder are thoroughly mixed to form a uniform powder mixture, a specific amount of water is added and mixed to form a powder-water mixture, which causes the water-insoluble compound to adhere uniformly to the pigment powder, and then the water is heated and aged to surface-treat the pigment powder with the water-insoluble compound. Therefore, compared to conventional methods, the water-insoluble compound can be uniformly adhered to the pigment surface. [Modes for carrying out the invention]

[0012] Next, a specific embodiment of the surface treatment method for pigment powder according to the present invention will be described.

[0013] 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 adding 0.1% to 30% by mass of water relative to the pigment powder to the powder mixture to form a powder-water mixture, and then heating and aging the mixture to evaporate and remove the water, and optionally grinding the mixture 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 is a method of drying at a high temperature (70-120°C) for several hours.

[0014] For mixing and dispersing the pigment powder with the water-insoluble compound and water, a reaction vessel with stirring blades, a disper, 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.

[0015] 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 aggregate, making it difficult to obtain a well-mixed powder-water mixture, and it will take a long time to dry the water sufficiently, resulting in reduced productivity. The minimum required amount of aqueous solvent is 0.1% by mass relative to the powder mixture. If it is less than 0.1% by mass, the effect of surface treatment by the water-insoluble compound will not be obtained, which is undesirable.

[0016] In the present 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.

[0017] The water-insoluble compounds, which are ceramides, according to the present invention can be one or more selected from natural ceramides and pseudo-ceramides. Specifically, the ceramides described in Japanese Patent Application Publication No. 2013-53146 can be used. Examples of commercially available natural 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 (manufactured by Quest International Co., Ltd.), DS-Ceramide VI, DS-CLA-Phytoceramide, C6-Phytoceramide, DS-ceramide Y3S (manufactured by Doosan Inc.), and CERAMIDE2 (manufactured by Sederma Inc.).

[0018] Examples of water-insoluble compounds, or higher fatty acids, according to the present invention include lauric acid, myristic acid, palmitic acid, and stearic acid, which are solid at room temperature.

[0019] Examples of the water-insoluble compounds, or higher alcohols, according to the present invention include myristyl alcohol, cetanol, cetearyl alcohol, stearyl alcohol, arachidyl alcohol, and behenyl alcohol, which are saturated aliphatic alcohols with 14 or more carbon atoms that are solid at room temperature.

[0020] The alkylglyceryl ethers, which are poorly water-soluble compounds according to the present invention, are a general term for compounds in which an ether bond is formed between the hydroxyl group of glycerol and an alcohol, and which have an alkyl group.

[0021] The above alkyl glyceryl ether may be any of monoalkyl glyceryl ether, dialkyl glyceryl ether, or trialkyl glyceryl ether, or a mixture thereof. Among these, monoalkyl glyceryl ether is preferred, and it preferably has a linear or branched alkyl group, and more preferably has 14 to 22 carbon atoms in the alkyl group. This alkyl glyceryl ether is solid at room temperature, and examples thereof include batyl alcohol and chimyl alcohol.

[0022] The fatty acid ester, which is a water-insoluble compound according to the present invention, is an ester of a fatty acid that is solid at room temperature and a higher alcohol, and examples thereof include myristyl myristate and cetyl palmitate.

[0023] The propylene glycol fatty acid ester, which is a water-insoluble compound according to the present invention, is an ester of propylene glycol and a fatty acid, and examples thereof include propylene glycol monopalmitate and propylene glycol monostearate that are solid at room temperature.

[0024] The glycerin fatty acid ester, which is a water-insoluble compound according to the present invention, is an ester of glycerin and a fatty acid, and examples thereof include glyceryl myristate and glyceryl stearate, which are esters of a linear higher fatty acid that is solid at room temperature.

[0025] The polyglycerol fatty acid ester, which is a water-insoluble compound according to the present invention, is an ester of polyglycerol obtained by polymerizing glycerin and a fatty acid, and the degree of polymerization of glycerin is preferably 4 or less. When the degree of polymerization of glycerin exceeds 4, the hydrophilicity increases, and the water repellency of the surface-treated powder may not be obtained. Examples of the polyglycerol fatty acid ester include polyglyceryl-2 stearate and polyglyceryl-4 stearate that are solid at room temperature.

[0026] The sorbitan fatty acid esters, which are poorly water-soluble compounds according to the present invention, are esters of sorbitan and fatty acids, and include sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquistearate, and sorbitan tristearate, which are esters of linear higher fatty acids that are solid at room temperature.

[0027] The lecithin derivative, which is a poorly water-soluble compound according to the present invention, is a "hydrogenated lecithin" compound obtained by adding hydrogen to lecithin, which mainly consists of phospholipids, a major component of biological membranes. Those made from egg yolks are broadly classified as "egg yolk lecithin" and those made from soybeans as "soybean lecithin," and hydrogenated soybean lecithin, which is obtained by adding hydrogen to soybean lecithin, is also mentioned.

[0028] The alkyl phosphate, which is a poorly water-soluble compound according to the present invention, is an ester of phosphoric acid and an alcohol, and is preferably an ester with a linear higher alcohol having 16 or more carbon atoms, such as monocetyl phosphate, dicetyl phosphate, and distearyl phosphate.

[0029] In the present invention, among the water-insoluble compounds used, ceramides, alkyl glyceryl ethers, lecithin derivatives, and alkyl phosphates are particularly preferred because they provide excellent usability for surface-treated powders.

[0030] Examples of pigment powders used in the present invention include inorganic powders, organic powders, surfactant metal salt powders (metal soaps), colored pigments, pearl pigments, tar dyes, and the like.

[0031] Examples of inorganic powders include titanium dioxide, zirconium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, calcium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, talc, mica, kaolin, sericite, muscovite, synthetic mica, phlogopite, rose mica, biotite, lithium mica, silicic acid, anhydrous silicic acid, aluminum silicate, magnesium silicate, aluminum magnesium silicate, calcium silicate, barium silicate, strontium silicate, tungstate metal salts, hydroxyapatite, vermiculite, hydylite, bentonite, montmorillonite, hectorite, zeolite, ceramic powder, dicalcium phosphate, alumina, aluminum hydroxide, boron nitride, boron nitride, silica, and the like.

[0032] Examples of organic powders include polyamide powder, polyester powder, polyethylene powder, polypropylene powder, polystyrene powder, polyurethane powder, benzoguanamine powder, polymethylbenzoguanamine powder, polytetrafluoroethylene powder, polymethyl methacrylate powder, cellulose, silk powder, nylon powder, nylon 12, nylon 6, acrylic powder, acrylic elastomer, styrene-acrylic acid copolymer, divinylbenzene-styrene copolymer, vinyl resin, urea resin, phenolic resin, fluororesin, silicon resin, acrylic resin, melamine resin, epoxy resin, polycarbonate resin, microcrystalline fiber powder, starch powder, and lauroyl lysine.

[0033] Examples of surfactant metal salt powders (metal soaps) include zinc stearate, aluminum stearate, calcium stearate, magnesium stearate, zinc myristate, magnesium myristate, zinc cetyl phosphate, calcium cetyl phosphate, and sodium zinc cetyl phosphate.

[0034] Examples of colored pigments include inorganic red pigments such as iron oxide, iron hydroxide, and iron titanate; inorganic brown pigments such as γ-iron oxide; inorganic yellow pigments such as yellow iron oxide and ochre; inorganic black pigments such as black iron oxide and carbon black; inorganic purple pigments such as manganese violet and cobalt violet; inorganic green pigments such as chromium hydroxide, chromium oxide, cobalt oxide, and cobalt titanate; inorganic blue pigments such as Prussian blue and ultramarine; fine particle powders such as fine particle titanium dioxide, fine particle cerium oxide, and fine particle zinc oxide; lake-formed tar-based dyes; lake-formed natural dyes; and synthetic resin powders that are composites of these powders.

[0035] Examples of pearl pigments include titanium dioxide-coated mica, bismuth oxychloride, titanium dioxide-coated bismuth oxychloride, titanium dioxide-coated talc, fish scale foil, and titanium dioxide-coated colored mica; examples of metal powder pigments include powders selected from aluminum powder, copper powder, stainless steel powder, etc.

[0036] Examples of tar dyes include Red No. 3, Red No. 104, Red No. 106, Red No. 201, Red No. 202, Red No. 204, Red No. 205, Red No. 220, Red No. 226, Red No. 227, Red No. 228, Red No. 230, Red No. 401, Red No. 505, Yellow No. 4, Yellow No. 5, Yellow No. 202, Yellow No. 203, Yellow No. 204, Yellow No. 401, Blue No. 1, Blue No. 2, Blue No. 201, Blue No. 404, Green No. 3, Green No. 201, Green No. 204, Green No. 205, Orange No. 201, Orange No. 203, Orange No. 204, Orange No. 206, Orange No. 207, etc.; Examples of natural pigments include pigments selected from carminic acid, laccaic acid, calsamine, brazilin, crocin, etc.

[0037] The amount of water-insoluble compound used in this invention coating the pigment powder varies depending on the particle size of the pigment powder, but is preferably 0.1 to 10% by mass. If this coating amount is less than 0.1% by mass, sufficient water repellency may not be obtained, and if it exceeds 10% by mass, the texture may become heavy. [Examples]

[0038] Next, representative embodiments of the present invention will be described. Note that these embodiments do not limit the technical scope of the present invention.

[0039] 980g of titanium dioxide pigment and 20g of the water-insoluble compounds shown in Table 1 were placed in a Henschel mixer and uniformly dispersed. 200g of water was then added and stirred until uniformly dispersed. The mixture was then dried at 90°C for 6 hours, and pulverized in an atomizer to obtain the surface-treated powders for Examples 1-7 and Comparative Example 1 as shown in Table 1.

[0040] (Example 8) 980g of zinc oxide and 20g of myristyl myristate were placed in a Henschel mixer and uniformly dispersed. 200g of water was then added and stirred until uniformly dispersed. The mixture was then dried at 90°C for 6 hours, and pulverized in an atomizer to obtain myristyl myristate surface-treated powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0041] (Example 9) 980g of talc and 20g of propylene glycol monostearate were placed in a Henschel mixer and dispersed uniformly. 200g of water was then added and stirred until uniformly dispersed. The mixture was then dried at 120°C for 6 hours, and pulverized in an atomizer to obtain a surface-treated propylene glycol monostearate powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0042] (Example 10) 980g of nylon powder and 20g of glyceryl stearate were placed in a Henschel mixer and dispersed uniformly. 200g of water was then added and stirred to further disperse uniformly. The mixture was then dried at 90°C for 6 hours, and pulverized in an atomizer to obtain glyceryl stearate surface-treated powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0043] (Example 11) 980g of magnesium stearate and 20g of polyglyceryl-2 stearate were placed in a Henschel mixer and uniformly dispersed. Further mixing and uniform dispersion were achieved by adding 200g of water. The mixture was then dried at 90°C for 6 hours, and pulverized in an atomizer to obtain polyglyceryl-2 stearate surface-treated powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0044] (Example 12) 980g of red iron oxide and 20g of sorbitan tristearate were placed in a Henschel mixer and dispersed uniformly. 200g of water was then added and stirred to further disperse uniformly. The mixture was then dried at 110°C for 6 hours, and pulverized in an atomizer to obtain sorbitan tristearate surface-treated powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0045] (Example 13) 980g of titanium dioxide-coated mica and 20g of behenyl alcohol were placed in a Henschel mixer and uniformly dispersed. Further mixing and uniform dispersion were achieved by adding 200g of water. The mixture was then dried at 110°C for 6 hours, pulverized in an atomizer, and a behenyl alcohol surface-treated powder was obtained. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0046] (Example 14) 980g of Red No. 202 and 20g of monocetyl phosphate were placed in a Henschel mixer and dispersed uniformly. Further mixing and dispersion were carried out by adding 200g of water. The mixture was then dried at 90°C for 6 hours, and pulverized in an atomizer to obtain monocetyl phosphate surface-treated powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0047] (Example 15) 950g of fine titanium dioxide (MT-05, manufactured by Teika Co., Ltd.) and 50g of hydrogenated lecithin (NIKKOL Lesinol S-10, manufactured by Nikko Chemicals Co., Ltd.) were placed in a Henschel mixer and uniformly dispersed. 300g of water was then added and stirred to further uniform dispersion. The mixture was then dried at 90°C for 6 hours and pulverized in an atomizer to obtain a hydrogenated lecithin surface-treated powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0048] (Example 16) A stearic acid surface-treated powder was obtained in the same manner as in Example 4, except that the titanium dioxide pigment was changed to 990 g and the stearic acid to 10 g. The results of the water repellency evaluation of the surface-treated powder are shown in Table 1.

[0049] (Example 17) A natural ceramide surface-treated powder was obtained in the same manner as in Example 1, except that the titanium dioxide pigment was changed to 920 g and the natural ceramide to 80 g. The evaluation results of the water repellency and usability (spreadability) of the surface-treated powder are shown in Table 1.

[0050] (Example 18) 900g of titanium dioxide pigment and 100g of myristyl myristate were placed in a Henschel mixer and uniformly dispersed. 200g of water was then added and stirred until uniformly dispersed. Afterward, the mixture was dried at 90°C for 6 hours, and then pulverized in an atomizer to obtain myristyl myristate surface-treated powder. The results of the water repellency evaluation of this surface-treated powder are shown in Table 1.

[0051] (Comparative Example 2) 980g of titanium dioxide pigment and 20g of hydrogenated lecithin (NIKKOL Lesinol S-10, manufactured by Nikko Chemicals Co., Ltd.) were placed in a Henschel mixer and uniformly dispersed. The mixture was dried at 90°C for 6 hours and then pulverized in an atomizer to obtain hydrogenated lecithin surface-treated powder. The results of the water repellency evaluation of this surface-treated powder are shown in Table 1.

[0052] (Comparative Example 3) 980g of titanium dioxide pigment was placed in a Henschel mixer. 20g of hydrogenated lecithin (NIKKOL Lesinol S-10, manufactured by Nikko Chemicals Co., Ltd.) was previously dispersed in 200g of water. This aqueous dispersion was gradually added to the Henschel mixer while stirring, and mixed until uniform. After that, it was dried at 90°C for 6 hours and then pulverized in an atomizer to obtain hydrogenated lecithin surface-treated powder. The results of the water repellency evaluation of this surface-treated powder are shown in Table 1.

[0053] (Comparative Example 4) 980g of titanium dioxide pigment and 20g of hydrogenated lecithin (NIKKOL Lesinol S-10, manufactured by Nikko Chemicals Co., Ltd.) were placed in a Henschel mixer and uniformly dispersed. 0.9g of water was then added and stirred until uniformly dispersed. The mixture was then dried at 90°C for 6 hours and pulverized in an atomizer to obtain hydrogenated lecithin surface-treated powder. Table 1 shows the results of the water repellency evaluation of this surface-treated powder.

[0054] (Comparative Example 5) A natural ceramide surface-treated powder was obtained in the same manner as in Example 1, except that the titanium dioxide pigment was changed to 800 g and the natural ceramide to 200 g. The evaluation results of the water repellency and usability (spreadability) of the surface-treated powder are shown in Table 1.

[0055] [Table 1] <Water repellency> Weigh 0.2g of powder and press it in an IR tablet press at 100kgf / cm². 2 The powder was compressed for 5 minutes using a specific force to form pellets with a diameter of 1 cm. One drop of deionized water was dropped onto the surface of each pellet using a microsyringe, and the contact angle was measured three times 30 seconds after dropping to determine the water repellency of the powder. Note that NIKKOL in the table is manufactured by Nikko Chemicals Co., Ltd. <Sensation> Sensory evaluation tests regarding usability (spreadability) were conducted on the surface-treated powders of Example 1, Example 17, and Comparative Example 5 using five female panelists. The test was conducted in the form of a questionnaire, with each item assigned a score between 0 and 5 points, where 0 was considered poor and 5 was considered excellent. The results were expressed as the average score of all panelists.

[0056] From a comparison of Examples 1-18 and Comparative Examples 1-5 shown in Table 1, it is clear that the method according to the present invention, which includes the steps of thoroughly mixing a water-insoluble compound that is solid at room temperature and has ester bonds and / or hydroxyl groups in its molecular structure with a pigment powder to form a powder mixture, and adding 0.1% to 30% by mass of water relative to the pigment powder to the powder mixture to form a powder-water mixture, significantly increases the water repellency of the surface-treated powder compared to methods that do not add water to the powder mixture, methods that disperse the treatment agent in water beforehand and then add it, or methods that add a small amount of water to the powder mixture. This is because the water-insoluble compound is uniformly treated on the surface of the pigment powder by using the manufacturing method of the present invention. Furthermore, if the amount of coating with the water-insoluble compound exceeds 10% by mass, the texture may become heavy, so 10% by mass or less is preferable. [Industrial applicability]

[0057] Surface-treated pigment powders obtained by the manufacturing method of the present invention, which are solid at room temperature and contain water-insoluble compounds with ester bonds and / or hydroxyl groups in their molecular structure, are suitable for incorporation into makeup cosmetics such as foundations, eyeshadows, and blushes, or sunscreen cosmetics, and have great industrial potential.

Claims

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 production step includes a step of mixing the water-poorly soluble compound and the pigment powder to make a powder mixture, and a step of adding 20% ​​by mass or more and 30% by mass or less 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-insoluble compound coating the pigment powder is 0.1 to 10% by mass.

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