Powder manufacturing method

Abstract

Provided is a powder having excellent concealing power, such that the powder can be used in place of titanium dioxide as a white pigment in a cosmetic. This powder comprises planar crystal particles, the volume D50% diameter thereof is 0.7-8.0 µm, and the coefficient of variation (CV value) of the primary particle diameter is 1.0 or less.

Description

[Technical Field]

[0001] This invention relates to powders, white pigments for cosmetics, and cosmetics. [Background technology]

[0002] White pigments for cosmetics are base pigments used when mixing with other pigments to obtain cosmetic compositions. Traditionally, titanium(IV) dioxide (TiO2, titanium dioxide; hereinafter simply referred to as "titanium dioxide") has been commonly used as a white pigment for cosmetics. This is because titanium dioxide has a high refractive index and excellent opacity.

[0003] Patent Document 1 discloses aggregated rutile titanium dioxide particles, characterized in that they are formed by the aggregation and / or bonding of fan-shaped rutile titanium dioxide particles, which are rod-shaped particles having dimensions of 0.05 to 0.2 μm on the side and 0.02 to 0.1 μm in the thickness direction, and the aggregated particles have a particle size of 0.1 to 5.0 μm and an average coefficient of friction (MIU value) of 0.2 or more and less than 0.7. It is stated that when these aggregated rutile titanium dioxide particles are incorporated into cosmetics, especially makeup cosmetics, they can be applied smoothly to the skin without any squeaky or rough feeling, and provide a natural, bare-skin look without a white cast due to their moderate coloring and concealing power.

[0004] Patent Document 2 describes an oily solid cosmetic composition characterized by containing (A) 5 to 40% by weight of one or more solid waxes selected from microcrystalline wax, polyethylene polypropylene copolymer, polyethylene wax, ceresin wax, and paraffin wax, (B) 1 to 30% by weight of one or more fine powders selected from aluminum oxide and anhydrous silicic acid with a particle size of 0.1 μm or less, and (C) 30 to 80% by weight of a liquid oil, and having a gloss of 40% or more when both the angle of incidence and the angle of reflection are 60°.

[0005] Patent Document 3 describes a solid makeup and / or care cosmetic composition in compact powder form, comprising, in a physiologically acceptable medium, at least one powder phase, one emulsion system, one hydrophilic gelling agent, one organic lake, at least one organopolysiloxane elastomer, and one hygroscopic hydrophilic active agent present in a content between 1% and 40% by mass relative to the total mass of the composition, and having a solid content of 90% by mass or more relative to the total mass of the composition.

[0006] It is also stated that the composition contains 35% by mass or more of a powder phase (filler, pearlescent material, inorganic pigment, reflective particles), and organic lake in total amount from 0.01% by mass to 20% by mass relative to the total mass of the composition, and that the emulsifying system includes sugar esters and ethers, fatty acid esters, oxyalkylene alcohols, fatty alcohols, and silicone compounds, with a solid content between 0.5% and 8% relative to the total weight of the composition, and that the hydrophilic gelling agent can be selected from thickening fillers, polymeric thickeners, and associative polymers. Furthermore, it is stated that a composition of a particular embodiment may advantageously include a chelating agent selected from aminocarboxylic acids such as tetrasodium EDTA.

[0007] Patent Document 4 describes a cosmetic composition in the form of a water-in-oil solid emulsion in which an aqueous phase is dispersed in a lipid phase, wherein the lipid phase comprises at least one type of wax, which is a solid form of needle-shaped crystals with a melting point of 25 to 42°C, an average length of 0.1 to 50 μm, and a shape factor of 2 or more, and the maximum force measured by texturerometry while the probe penetrates the composition is 0.25 Newtons or more.

[0008] It is also stated that the aqueous phase contains 50% by weight of water or a water-miscible organic solvent, and the lipid phase contains 2-65% liquid oil. The composition may also contain a particulate phase, which is present in an amount of 0.01-40% by weight, more preferably 0.01-30% by weight, and particularly 0.05-20% by weight of the total weight of the composition. The particulate phase is said to contain pigments and / or pearl components and / or fillers commonly used in cosmetic compositions. It is also stated that pigments are white or colored mineral or organic particles insoluble in the liquid hydrophilic phase, used to give color and / or opacity to the composition. Fillers are colorless or white mineral or synthetic flake or non-flaky particles. Pearl components are said to be pearly particles produced from shelled mollusks or synthetic pearly particles.

[0009] Patent Document 5 describes a cosmetic composition containing (A) a powder made of Nε-monooctanoyllysine, (B) an inorganic powder, and (C) an oil, wherein the content of component (A) is 0.1 to 95% by weight of the entire cosmetic composition, the content of component (B) is 4 to 99.5% by weight of the entire cosmetic composition, the content of component (C) is 0.01 to 95% by weight of the entire cosmetic composition, the mixing ratio of component (A) to component (B) (weight of component (A):weight of component (B)) is 1:99 to 60:40, and the mixing ratio of component (A) to component (C) (weight of component (A):weight of component (C)) is 15:85 to 75:25.

[0010] Furthermore, examples of inorganic powders include yellow iron oxide, red iron oxide, black iron oxide, fine-particle iron oxide, bismuth oxychloride, carbon black, and zinc oxide. The oils are not particularly limited as long as they are commonly used in cosmetics, and examples include petrolatum, lanolin, and ceresin. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Patent No. 4684970

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0012] However, titanium dioxide may be a carcinogenic substance and will be classified as Carcinogenic Category 2 under the CLP Regulation in the EU. Therefore, it is predicted that its use in cosmetics will be restricted in the future. An object of the present invention is to provide a powder with excellent hiding power that can be used in cosmetics as a white pigment代替 titanium dioxide.

Means for Solving the Problems

[0013] To solve the above problems, one aspect of the present invention provides a powder composed of plate-like crystal particles, wherein the cumulative 50% primary particle diameter (volume D50% diameter) based on volume is 0.7 μm or more and 8.0 μm or less, and the coefficient of variation (CV value = standard deviation / number average primary particle diameter) of the primary particle diameter is 1.0 or less.

Effects of the Invention

[0014] According to this invention, it becomes possible to provide a powder with excellent hiding power that can be used in cosmetics as a white pigment代替 titanium dioxide.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are made to carry out the present invention, but these limitations are not essential requirements of the present invention.

[0016] [First Embodiment] The white pigment for cosmetics in this embodiment is composed of titanium phosphate powder. This titanium phosphate powder is composed of titanium phosphate crystal particles. These titanium phosphate crystal particles are plate-shaped crystal particles. By means of an image analysis method, the longest diagonal line of the plate surface of this plate-shaped crystal was measured as the primary particle diameter, and the value of the volume-based cumulative 50% primary particle diameter (volume D50% diameter) calculated was 0.7 μm or more and 8.0 μm or less, and the coefficient of variation (CV value = standard deviation / number-average primary particle diameter) of the primary particle diameter was 1.0 or less. Also, the thickness of the side surface of this plate-shaped crystal was measured, and the value of the volume-based cumulative 50% thickness (volume D50% thickness) calculated was 0.01 μm or more and less than 1.00 μm, and the aspect ratio (the value obtained by dividing the volume D50% diameter by the volume D50% thickness) was 5 or more.

[0017] The white pigment for cosmetics in this embodiment is composed of a titanium phosphate powder composed of plate-shaped crystal particles of titanium phosphate. The volume D50% diameter of the titanium phosphate powder is 0.7 μm or more and 8.0 μm or less, and the coefficient of variation (CV value) of the primary particle diameter of the titanium phosphate powder is 1.0 or less. Therefore, the cosmetic containing this has excellent hiding power. Also, if the volume D50% thickness of these plate-shaped crystal particles is less than 0.01 μm, plate-shaped particles are not formed, and if it exceeds 1.00 μm, the hiding power decreases. Therefore, the thickness (volume D50% thickness) of the plate-shaped crystal particles is set to 0.01 μm or more and 1.00 μm or less. Furthermore, since the aspect ratio is 5 or more, it also has excellent slipperiness.

[0018] This titanium phosphate powder can be obtained, for example, by the following method. First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid are mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] is between 5 and 21 to obtain a mixture. Next, this mixture is placed in a sealed container and the temperature is maintained within the range of 100°C to 160°C, and the mixture is allowed to react for a predetermined time (for example, 5 hours or more). In other words, hydrothermal synthesis is performed. The pressure inside the sealed container is naturally determined by the pressurizing temperature and is above atmospheric pressure. This yields a slurry containing titanium phosphate crystal particles. Next, the obtained slurry is cooled, and then the solid components (crystalline titanium phosphate particles) are separated from the slurry. The obtained solid components are washed with a washing solution consisting of water or ammonia water (ammonium hydroxide), and then dried.

[0019] [Second Embodiment] The white pigment for cosmetics in this embodiment consists of boron nitride powder. This boron nitride powder consists of boron nitride crystalline particles. These boron nitride crystalline particles are plate-shaped crystalline particles. Using image analysis, the longest diagonal of the plate surface of this plate-like crystal was measured as the primary particle diameter, and the value calculated as the volume-based cumulative 50% primary particle diameter (volume D50% diameter) was between 0.7 μm and 8.0 μm, with a coefficient of variation (CV value = standard deviation / number mean primary particle diameter) of 1.0 or less. In addition, the thickness of the side surface of this plate-like crystal was measured, and the value calculated as the volume-based cumulative 50% thickness (volume D50% thickness) was between 0.01 μm and less than 1.00 μm, with an aspect ratio (volume D50% diameter divided by volume D50% thickness) of 5 or more. The cosmetic composition containing the white pigment for cosmetic composition in this embodiment, like the cosmetic composition containing the white pigment for cosmetic composition in the first embodiment, has excellent opacity and also excellent slipperiness. The white pigment for cosmetics in this embodiment can be obtained by grinding commercially available boron nitride powder.

[0020] [About cosmetics] Examples of cosmetics comprising a composition containing a powdered white pigment (hereinafter referred to as "cosmetic composition") include makeup cosmetics such as foundation, face powder, blush, eye color, nail polish, and lipstick, as well as skincare cosmetics such as whitening powder and body powder. The white pigments of the first and second embodiments are suitable as white pigments for these cosmetic compositions because they have high opacity.

[0021] Furthermore, examples of cosmetics include those described in Patent Documents 2 to 5. The powder according to one embodiment of the present invention can be used as the fine particle powder constituting the oily solid cosmetic composition in Patent Document 2, as the inorganic pigment of the powder phase constituting the solid makeup and / or care cosmetic composition in compact powder form in Patent Document 3, as the pigment of the particle phase constituting the cosmetic composition in the form of a water-in-oil solid emulsion in Patent Document 4, and as the inorganic powder constituting the cosmetic composition in Patent Document 5.

[0022] Furthermore, powders according to one embodiment of the present invention (for example, titanium phosphate powder of the first embodiment, boron nitride powder of the second embodiment) may be used after various polymer treatments or the following treatments to improve cosmetic properties and pigment properties. Examples of these treatment methods include fluorine treatment, silicon treatment, alkylsilane treatment, alkyl titanate treatment, metal soap treatment, lauroyl lysine treatment, ester treatment, and amino acid treatment. For amino acid treatment, proline, hydroxyproline, alanine, glycine, sarcosine, aspartic acid, and glutamic acid can be used.

[0023] A cosmetic composition containing a white pigment made from a powder according to one embodiment of the present invention (for example, titanium phosphate powder in the first embodiment, or boron nitride powder in the second embodiment) may contain other components as needed, as long as the effects of the present invention are not impaired. Other components include those commonly used in cosmetics, such as solvents, oils, surfactants, humectants, organic ultraviolet absorbers, antioxidants, thickeners, fragrances, colorants, physiologically active ingredients, and antibacterial agents. Other ingredients may be used individually or in combination of two or more. The amount of other ingredients is not particularly limited and can be set as appropriate depending on the purpose. The content of the powder according to one embodiment of the present invention (for example, titanium phosphate powder in the first embodiment, or boron nitride powder in the second embodiment) in the cosmetic composition is preferably 0.1% by mass or more and 50% by mass or less of the total cosmetic composition. [Examples]

[0024] [Synthesis of titanium phosphate] Six types of titanium phosphate (A-F) were synthesized using the following method. <Synthetic product A> First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid were mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] was 9.0 to obtain a mixture. Next, this mixture was placed in a 1.4 L autoclave and reacted for 5 hours while maintaining the temperature at 110°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature. Then, it was removed from the container and the solid component was separated from the slurry by filtration. This solid component was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0025] Analysis of the obtained powder using an X-ray diffractometer confirmed that the particles constituting the powder are crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. Observation of the obtained powder using a scanning electron microscope revealed that the particles constituting the powder were plate-shaped, and that many of them were hexagonal plate-shaped. By analyzing the scanning electron microscope images using "Mac-View ver.4," image analysis software manufactured by Mountec Co., Ltd., the volume D50% diameter, CV value (standard deviation / number mean primary particle diameter), and volume D50% thickness of the crystalline particles constituting the obtained powder were measured. The volume D50% diameter was found to be 0.29 μm, the CV value 0.45, and the volume D50% thickness 0.030 μm. Furthermore, calculations using the measured values ​​of volume D50% thickness and volume D50% diameter (0.29 / 0.030) showed that the aspect ratio of the crystalline particles constituting the obtained powder was 10.

[0026] <Synthetic product B> First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid were mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] was 10.7 to obtain a mixture. Next, this mixture was placed in a 1.4 L autoclave and reacted for 5 hours while maintaining the temperature at 110°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature. Then, it was removed from the container and the solid component was separated from the slurry by filtration. This solid component was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0027] Analysis of the obtained powder using an X-ray diffractometer confirmed that the particles constituting the powder are crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. Observation of the obtained powder using a scanning electron microscope revealed that the particles constituting the powder were plate-shaped, and that many of them were hexagonal plate-shaped. Furthermore, using the same method as for synthesized product A, the volume D50% diameter, CV value (standard deviation / number mean primary particle diameter), and volume D50% thickness of the crystalline particles constituting the obtained powder were measured. The volume D50% diameter was 0.53 μm, the CV value was 0.34, and the volume D50% thickness was 0.065 μm. Furthermore, calculations using the measured values ​​of volume D50% thickness and volume D50% diameter (0.53 / 0.065) showed that the aspect ratio of the crystalline particles constituting the obtained powder was 8.

[0028] <Synthetic product C> First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid were mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] was 10.4 to obtain a mixture. Next, this mixture was placed in a 1.4 L autoclave and reacted for 5 hours while maintaining the temperature at 110°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature. Then, it was removed from the container and the solid component was separated from the slurry by filtration. This solid component was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0029] Analysis of the obtained powder using an X-ray diffractometer confirmed that the particles constituting the powder are crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. Observation of the obtained powder using a scanning electron microscope revealed that the particles constituting the powder were plate-shaped, and that many of them were hexagonal plate-shaped. Furthermore, using the same method as for synthesized product A, the volume D50% diameter, CV value (standard deviation / number mean primary particle diameter), and volume D50% thickness of the crystalline particles constituting the obtained powder were measured. The volume D50% diameter was 0.74 μm, the CV value was 0.42, and the volume D50% thickness was 0.090 μm. Furthermore, calculations using the measured values ​​of volume D50% thickness and volume D50% diameter (0.74 / 0.090) showed that the aspect ratio of the crystalline particles constituting the obtained powder was 8.

[0030] <Synthetic product D> First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid were mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] was 10.2 to obtain a mixture. Next, this mixture was placed in a 200 L autoclave and reacted for 5 hours while maintaining the temperature at 110°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature. Then, it was removed from the container and the solid component was separated from the slurry by filtration. This solid component was washed with 29% aqueous ammonia (aqueous solution of ammonium salt), and then dried (at 105°C for 24 hours) to obtain a powder.

[0031] Analysis of the obtained powder using an X-ray diffractometer confirmed that the particles constituting the powder are crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed with a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, and that many of them were hexagonal plate-shaped. Furthermore, using the same method as for synthesized product A, the volume D50% diameter, CV value (standard deviation / number mean primary particle diameter), and volume D50% thickness of the crystalline particles constituting the obtained powder were measured, and the volume D50% diameter was 1.11 μm, the CV value was 0.33, and the volume D50% thickness was 0.143 μm. Furthermore, calculations using the measured values ​​of volume D50% thickness and volume D50% diameter (1.11 / 0.143) showed that the aspect ratio of the crystalline particles constituting the obtained powder was 8.

[0032] <Synthetic product E> First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid were mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] was 6.9 to obtain a mixture. Next, this mixture was placed in a 1.4 L autoclave and reacted for 5 hours while maintaining the temperature at 120°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature. Then, it was removed from the container and the solid component was separated from the slurry by filtration. This solid component was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0033] Analysis of the obtained powder using an X-ray diffractometer confirmed that the particles constituting the powder are crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed with a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, and that many of them were hexagonal plate-shaped. Furthermore, using the same method as for synthesized product A, the volume D50% diameter, CV value (standard deviation / number mean primary particle diameter), and volume D50% thickness of the crystalline particles constituting the obtained powder were measured, and the volume D50% diameter was 2.07 μm, the CV value was 0.37, and the volume D50% thickness was 0.302 μm. Furthermore, calculations using the measured values ​​of volume D50% thickness and volume D50% diameter (2.07 / 0.302) showed that the aspect ratio of the crystalline particles constituting the obtained powder was 7.

[0034] <Synthetic product F> First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid were mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] was 10.8 to obtain a mixture. Next, this mixture was placed in a 200 L autoclave and reacted for 5 hours while maintaining the temperature at 130°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature. Then, it was removed from the container and the solid component was separated from the slurry by filtration. This solid component was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0035] Analysis of the obtained powder using an X-ray diffractometer confirmed that the particles constituting the powder are crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed with a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, and that many of them were hexagonal plate-shaped. Furthermore, using the same method as for synthesized product A, the volume D50% diameter, CV value (standard deviation / number mean primary particle diameter), and volume D50% thickness of the crystalline particles constituting the obtained powder were measured, and the volume D50% diameter was 7.44 μm, the CV value was 0.36, and the volume D50% thickness was 0.856 μm. Furthermore, calculations using the measured values ​​of volume D50% thickness and volume D50% diameter (7.44 / 0.856) showed that the aspect ratio of the crystalline particles constituting the obtained powder was 9.

[0036] [Preparation of powders] The synthesized titanium phosphate powders A to F were mixed in the proportions shown in Table 1 below to obtain titanium phosphate powders No. 1 to No. 9. Titanium phosphate powders No. 1 to 3 and No. 7 are the same as synthesized titanium phosphate powders A to D, respectively. Since titanium phosphate powders No. 4 to No. 6, No. 8, and No. 9 are mixtures, the diameter at volume D50%, CV value, and thickness at volume D50% were measured using the method described above, and the aspect ratio was calculated. Furthermore, commercially available boron nitride powder (No. 10) with a volume D50% diameter of 9.94 μm was prepared and pulverized in a pot mill to obtain boron nitride powders No. 11 to No. 14 with the configurations shown in Table 2. For these boron nitride powders as well, the volume D50% diameter, CV value, and volume D50% thickness were measured using the method described above, and the aspect ratio was calculated. Furthermore, commercially available titanium dioxide powder (No. 15) was prepared.

[0037] In addition, titanium phosphate powder No. 16 was synthesized by the following method. First, an aqueous solution of titanyl sulfate and an aqueous solution of phosphoric acid were mixed in a ratio [P] / [Ti] such that the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] was 18.1 to obtain a mixture. Next, this mixture was placed in a 200 L autoclave and reacted for 10 hours while maintaining the temperature at 130°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature. Then, it was removed from the container and the solid component was separated from the slurry by filtration. This solid component was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0038] Analysis of the obtained powder using an X-ray diffractometer confirmed that the particles constituting the powder are crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. Observation of the obtained powder using a scanning electron microscope revealed that the particles constituting the powder were plate-shaped, and that many of them were hexagonal plate-shaped. Furthermore, using the same method as for synthesized product A, the volume D50% diameter, CV value (standard deviation / number mean primary particle diameter), and volume D50% thickness of the crystalline particles constituting the obtained powder were measured. The volume D50% diameter was 8.87 μm, the CV value was 0.38, and the volume D50% thickness was 0.930 μm. Furthermore, calculations using the measured values ​​of volume D50% thickness and volume D50% diameter (8.87 / 0.930) showed that the aspect ratio of the crystalline particles constituting the obtained powder was 10. Table 2 shows the volume D50% diameter, CV value, volume D50% thickness, and aspect ratio for each powder.

[0039] [Measurement of Hiding Power] The hiding powers of Powders No. 1 to No. 16 were measured by the following method. First, 1.4 g of ethanol and 5.6 g of a 10% collodion solution were added to 3 g of each powder and mixed to obtain a slurry. Next, the obtained slurry was applied and dried on a black-and-white hiding rate test paper with a film thickness of 100 μm in accordance with JIS K5600-4 (General Test Methods for Paints - Test Methods for Visual Properties of Paint Films) to obtain test samples. Next, using a spectrophotometer (Konica Minolta's "CM-512m3A"), the light incident on the obtained test sample at an angle of 45° was received directly above (0°) to perform colorimetry on a white background and a black background, and the color difference (ΔE) in the L * , a * , b * color system was calculated. (L * 1, a * 1, b * 1) are the colorimetric values on the black background, and (L * 2, a * 2, b * 2) are the colorimetric values on the white background. The hiding power was calculated from Equation (2) using ΔE. The results are also shown in Table 2. ΔE = √{(L * 2 - L * 1) 2 + (a * 2 - a * 1) 2 + (b * 2 - b * 1) 2}…(1)[[ID=U+217]] Hiding power = 100 / ΔE…(2)

[0040]

Table 1

[0041]

Table 2

[0042] From these results, the following can be understood. The titanium phosphate powders and boron nitride powders No. 3-5, No. 7-9, and No. 12-14, which consist of plate-like crystalline particles, have a volume D50% diameter of 0.7 μm or more and 8.0 μm or less, a coefficient of variation (CV value) of primary particle diameter of 1.0 or less, and a volume D50% thickness of 0.01 μm or more and less than 1.00 μm, have a high hiding power of 20 to 36. In particular, the hiding power of titanium phosphate powder No. 7 was higher than that of titanium dioxide powder No. 15. In contrast, the opacity of titanium phosphate powders No. 1 and No. 2, boron nitride powder No. 11, which have a volume D50% diameter of less than 0.7 μm, titanium phosphate powder No. 6, which has a CV value greater than 1.0, titanium phosphate powder No. 16, which has a volume D50% diameter greater than 8.0 μm, and boron nitride powder No. 10, which has a volume D50% diameter greater than 8.0 μm, was low, at 15, 14, 9, 7, 12, and 18, respectively.

[0043] In other words, titanium phosphate powders No. 3-5, No. 7-9, and No. 12-14, as well as boron nitride powders, were powders with excellent opacity that could be used in cosmetics as a white pigment to replace titanium dioxide. Furthermore, having an aspect ratio of 5 or higher also provides the effect of excellent slipperiness. Furthermore, titanium phosphate powders No. 5, No. 7, and No. 12, and boron nitride powders had particularly high hiding power of 29 or higher. In other words, powders consisting of plate-like crystalline particles with a volume-based cumulative 50% primary particle diameter (volume D50% diameter) of 0.97 μm or more and 1.84 μm or less are preferred because they have particularly high hiding power. Also, titanium phosphate powders consisting of plate-like crystalline particles with a volume-based cumulative 50% thickness (volume D50% thickness) of plate-like crystalline particles of 0.142 μm or more and 0.143 μm or less are preferred because they have particularly high hiding power.

[0044] [Formulation of cosmetic compositions] When cosmetic compositions containing titanium phosphate powders No. 3-5, No. 7-9, and No. 12-14, and boron nitride powders as white pigments were formulated, they exhibited high opacity, resulting in an enhanced effect of covering skin color and adjusting skin tone.

[0045] [Measurement of whiteness, refractive index, oil absorption, and specific surface area] The whiteness, refractive index, oil absorption, and specific surface area of ​​each powder from No. 1 to No. 16 were measured using the following method. Whiteness was measured using a UV-Vis spectrophotometer "UV-2450" manufactured by Shimadzu Corporation, under illumination D65 and field of view 2°. In other words, the whiteness of each powder was measured in accordance with JIS Z 8715. To determine the refractive index, first, each of the obtained powders was mixed with polymethyl methacrylate (film substrate: a transparent resin that forms the base of the film) in N-methylpyrrolidone (a solvent capable of dissolving the film substrate) to disperse the powders and obtain a liquid in which the polymethyl methacrylate was dissolved. Multiple such liquids were obtained by varying the powder content. Using these liquids, a coating film with a thickness of 600 μm was formed on a PET film and dried at 80°C to form a film consisting only of powder and resin. After cooling, this film was peeled off the PET film.

[0046] The refractive indices of the multiple films obtained in this manner were measured using a Metricon Prism Coupler Model 2010 / M refractometer with a helium-neon laser light source of 632.8 nm wavelength. The measured refractive indices of the multiple films were plotted on a graph with powder content (volume %) on the x-axis and refractive index on the y-axis, and each plot was approximated by a straight line. The refractive index value at the point where this straight line was extrapolated to the point where the powder content reached 100% was defined as the refractive index of the powder.

[0047] Oil absorption was measured per 100g according to the method conforming to JIS K 5101-13. Specific surface area was measured using the BET flow method with Mountec Co., Ltd.'s fully automatic specific surface area measuring device "Macsorb(registered trademark) HM-1210". Furthermore, using these measured values, the specific surface area (m²) of the crystalline particles in each powder was calculated. 2 The ratio of oil absorption (ml / 100g) to oil absorption (oil absorption / specific surface area) was calculated. The results are shown in Table 3. In Table 3, SA represents the specific surface area.

[0048] [Table 3]

[0049] From these results, we can conclude the following: Each of the powders No. 1-9 and No. 16 has a high whiteness of 92.91 or higher, as measured in accordance with JIS Z 8715, allowing them to exhibit high functionality as base pigments. Furthermore, each of the powders No. 1-9 and No. 16 has a refractive index of 1.67 to less than 1.80, which is moderately higher than the refractive index of human skin (1.5). Therefore, by using a cosmetic composition in which each of these powders is blended, a natural finish can be obtained with moderate coverage without a white cast. In addition, each of the powders No. 1-9 and No. 16 has a specific surface area (m²) of crystalline particles. 2 Since the ratio of oil absorption (ml / 100g) to (saturation) (oil absorption / SA) is 4.0 or higher, the cosmetic composition in which each powder is blended results in a less sticky coating film and good makeup retention.

Claims

1. A method for producing a powder containing plate-shaped crystalline particles made of titanium phosphate, A step of preparing a mixed solution obtained by mixing titanium and phosphorus in a ratio [P] / [Ti] such that the ratio of the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti] is 6.9 or more and 10.8 or less, The process includes producing a powder containing plate-shaped crystalline particles made of titanium phosphate from the aforementioned mixture, In the powder obtained, The volume-based cumulative 50% primary particle diameter (volume D50% diameter) is between 0.7 μm and 8.0 μm. A method for producing powder in which the coefficient of variation (CV value) of the primary particle size is 1.0 or less.

2. The volume-based cumulative 50% thickness (volume D50% thickness) of the aforementioned plate-like crystalline particles is 0.01 μm or more and less than 1.00 μm. The method for producing powder according to claim 1, wherein the aspect ratio, which is the value obtained by dividing the volume-based cumulative 50% primary particle diameter of the plate-like crystalline particles by the volume-based cumulative 50% thickness, is 5 or more.

3. The method for producing powder according to claim 1 or 2, wherein the plate-like crystalline particles are hexagonal plate-like crystalline particles.

4. A method for producing powder according to any one of claims 1 to 3, wherein the cumulative 50% primary particle diameter (volume D50% diameter) based on the volume is 0.97 μm or more and 1.97 μm or less.

5. The method for producing powder according to any one of claims 1 to 4, wherein the coefficient of variation (CV value) of the primary particle size is 0.48 or less.

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