Prussian blue dispersion for cosmetics, and cosmetics containing the same

Abstract

To provide: a Prussian blue dispersion for cosmetics which has excellent dispersion stability, color-forming properties (high chroma), and storage stability; and cosmetics which include the Prussian blue dispersion and which are suitable for makeup cosmetics such as eye shadow, eye liner, eyebrow makeup, and mascara.SOLUTION: A Prussian blue dispersion for cosmetics according to the present disclosure comprises at least Prussian blue, a water-soluble basic substance, and water. A cosmetic according to the present invention comprises the Prussian blue dispersion.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a Prussian blue dispersion for cosmetics that has excellent dispersion stability, color development (high saturation), and storage stability, and to cosmetics that contain this Prussian blue dispersion and are suitable for makeup cosmetics such as eye shadow, eyeliner, eyebrow pencil, and mascara. [Background technology]

[0002] Traditionally, Prussian blue has been used as a colorant, and mixed with extender pigments to color cosmetics, paints, inks for writing instruments, inks for printing, resins, etc. (see, for example, Non-Patent Document 1). This Prussian blue is made primarily of ferric ferrocyanide, and its general chemical structure is MFe[Fe(CN)6], where M=K, Na, NH4. Most commercially available Prussian blue is ammonium ferrocyanide, which has a deep blue color unique to Prussian blue and a high coloring power for an inorganic pigment. However, its stable pH is low at 4 to 6, and it is unstable in alkaline environments, which poses a problem (see, for example, Patent Documents 1 and 2, and Non-Patent Document 2). Depending on the alkaline conditions, discoloration may occur, and there are issues such as discoloration or loss of color when used in combination with alkaline extender pigments such as calcium carbonate or alumina. Furthermore, Prussian blue loses its blue color when reduced, and when kneaded in a vehicle that is easily oxidized and kept sealed, the Prussian blue acts as an oxidizing agent, which can reduce and cause discoloration.

[0003] On the other hand, in cosmetics and the like, Prussian blue has a greater tinting power than the blue pigment ultramarine, and can produce a highly saturated blue hue. In addition, for example, when used in combination with a yellow legal pigment, a highly saturated green can be produced. Therefore, there is a high demand for Prussian blue as a cosmetic ingredient. However, due to the above-mentioned issues, its use has been limited.

[0004] To solve these problems with Prussian blue, for example, a surface-treated powder (see Patent Document 1) is known, which is characterized by treating a surface-treated Prussian blue-coated powder with either or both of an α-hydroxycarboxylic acid and a coating-forming substance. Also, to use Prussian blue in cosmetics, a pigment dispersion for cosmetics containing black iron oxide, red iron oxide, and Prussian blue (see Patent Document 2) is known. However, the above Patent Document 1 does not have the color development properties of Prussian blue as it should be and has problems such as insufficient dispersion stability, and the above Patent Document 2 is about creating a mixed black dispersion liquid by simply blending three components, black iron oxide, red iron oxide, and Prussian blue, but does not mention the above-mentioned problems with Prussian blue, and is not about preparing a dispersion liquid in which Prussian blue has been previously maintained in dispersion stability and using this dispersion liquid, so the problems and technical ideas of the invention differ from those of the present invention. [Prior art documents] [Patent documents]

[0005] [Non-Patent Document 1] Latest Powder Properties Illustrated Guide (3rd Edition) (June 30, 2004, 3rd Edition, 1st Printing, 343 pages) [Non-patent document 2] "Introductory Course Text for Pigments", Color Material Association, 1970, pp. 114-118) [Patent Document 1] JP 2004-91645 A (claims, detailed description of the invention, etc.) [Patent Document 2] JP 2003-231614 A (claims, detailed description of the invention, etc.) Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above-mentioned problems and current state of the prior art, and aims to solve these problems, and to provide a Prussian blue dispersion for cosmetics that is excellent in dispersion stability, color development (high saturation), and storage stability, and a cosmetic that contains this Prussian blue dispersion and is suitable for makeup cosmetics such as eye shadow, eyeliner, eyebrow pencil, and mascara. [Means for solving the problem]

[0007] In view of the above-mentioned conventional problems, the present inventors have conducted extensive research and have found that the above-mentioned intended Prussian blue dispersion for cosmetics and cosmetics containing this Prussian blue dispersion can be obtained by containing at least Prussian blue, specific components, and water, thereby completing the present invention.

[0008] That is, the Prussian blue dispersion for cosmetics of the present invention is characterized by containing at least Prussian blue, a water-soluble basic substance, and water. When the amount of Prussian blue added is taken as 1 in mass ratio, the amount of the water-soluble basic substance is preferably contained in the range of 0.025 to 0.25. The water-soluble basic substance is preferably at least one selected from ammonia, a compound having an amino group, and an alkali metal hydroxide. When measuring viscosity using a cone-plate viscometer at 25°C, the shear rate was 383 s -1 It is preferable that the viscosity of the ink is 50 mPa·s or less. It is preferable that the average particle size of Prussian blue in the Prussian blue cosmetic dispersion be 200 nm or less as determined by cumulant method analysis in the scattering intensity distribution of Prussian blue. It is also preferable to contain a dispersant. The cosmetic of the present invention is characterized by containing the above-mentioned Prussian blue dispersion for cosmetics. [Effects of the Invention]

[0009] According to the present invention, there are provided a Prussian blue dispersion for cosmetics that has excellent dispersion stability, color development (high saturation), and storage stability, and cosmetics that are suitable for makeup cosmetics such as eye shadow, eyeliner, eyebrow pencil, and mascara that contain this Prussian blue dispersion. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. Both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed. [Brief explanation of the drawings]

[0010] [Figure 1] 1(a) shows an example of the cation arrangement diagram of Prussian blue (konjo), and FIG. 1(b) is an explanatory diagram outlining the mechanism for maintaining the dispersion stability of Prussian blue (konjo) of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes in detail the embodiments of the present invention. However, it should be noted that the technical scope of the present invention is not limited to the embodiments described in detail below, but extends to the inventions set forth in the claims and their equivalents. The Prussian blue cosmetic dispersion of the present invention is characterized by containing at least Prussian blue, a water-soluble basic substance, a dispersant, and water.

[0012] The chemical structure of the iron blue used in the present invention is generally represented by MKFe[Fe(CN)6] (where M is either K, Na or NH4), and the iron ion contains divalent iron (Fe II ) and trivalent iron (Fe III ) and Figure 1 shows the cation configuration of Prussian blue. The Prussian blue used in the present invention is not particularly limited as long as it is a Prussian blue that is commonly used in cosmetics, and preferably has an average particle size of 200 nm or less. Furthermore, ammonium konjo, where M is NH4, is preferred because of its ease of availability. Surface-modified products may also be used, and commercially available products can be used. Commercially available products include MILORI BLUE FX-6940 and FX-9050 manufactured by Dainichiseika Color & Chemicals Co., Ltd., Iron Blue SC manufactured by Daito Kasei Co., Ltd., and C38-7710 Softex Iron Blue manufactured by Sun Chemical Co., Ltd. The term "average particle size" in the present invention refers to the average particle size determined by cumulant analysis of the scattering intensity distribution, as will be described later.

[0013] This Prussian blue dispersion has problems such as a low stable pH of 4 to 6 and becoming unstable in alkaline conditions, and there are issues with productivity and dispersion stability when producing the dispersion, but if the dispersion is made to have the blending characteristics of the present invention, the above problems will be resolved. From the viewpoints of stability after dispersion and convenience in cosmetic production, the content of Prussian blue used is preferably 5 to 50 mass% (hereinafter, "mass%" will be simply referred to as "%"), and more preferably 10 to 30%, of the total amount of Prussian blue dispersion for cosmetics. By setting the content of Prussian blue to 5% or more, productivity will be excellent and the coloring properties when added to cosmetics will be excellent, while by setting it to 50% or less, dispersibility and stability over time will be even better.

[0014] According to the findings of the present inventors, the water-soluble basic substance used in the present invention converts Prussian blue into NH4 as shown in FIG. 1(b) when the dispersion of Prussian blue progresses in the dispersion liquid. + is eliminated, and NH4 + From H + The pH of the dispersion tends to decrease, and the absolute value of the zeta potential of Prussian blue at low pH tends to decrease. + The use of a water-soluble basic substance that acts as an alkaline agent to supplement the surface potential maintains the surface potential, dispersion stability, and microparticulation. Specific examples of water-soluble basic substances that can be used include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal carbonates such as potassium carbonate and sodium carbonate, ammonia, amines such as monomethylamine, dimethylamine, triethylamine, monoethylamine, diethylamine, ethylenediamine, monoethanolamine, diethanolamine, and triethanolamine, which are compounds having an amino group, basic amino acids such as aminomethylpropanol (2-amino-2-methyl-1-propanol), trishydroxymethylaminomethane, arginine, and lysine, aminoethylpropanolamine, aminomethylpropanediol, and aminoethylpropanediol, which can be used in combination, or at least one of the following (each alone or in combination: a mixture of two or more). In particular, the use of aminomethylpropanol and potassium hydroxide is preferred in order to minimize discoloration and aggregation of Prussian blue and to achieve further effects of the present invention.

[0015] In terms of dispersibility of Prussian blue and prevention of high viscosity, the content of the water-soluble basic substance used is preferably in the range of a mass ratio of 0.025 to 0.25, more preferably 0.05 to 0.13, and particularly preferably 0.05 to 0.10, when the mass of Prussian blue is taken as 1. If the mass ratio of this water-soluble basic substance is less than 0.025, gelation occurs during dispersion, and the effects of the present invention cannot be achieved. On the other hand, if the mass ratio exceeds 0.25, the viscosity after dispersion becomes high, reducing the degree of freedom in ink design.

[0016] The dispersant that can be used in the present invention is contained in order to adjust the viscosity and further improve the dispersion stability of Prussian blue, and examples thereof include at least one of surfactants, polymer dispersants, and the like. The surfactant may be any of commonly used surfactants such as anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, and polymer surfactants, or may be a mixture of two or more of these. Of these surfactants, nonionic surfactants are preferred from the viewpoints of obtaining more stable dispersibility of Prussian blue, low irritation, and elimination of influence on the dispersion state. Preferred nonionic surfactants include polyoxyethylene alkyl ethers such as laureths (polyoxyethylene lauryl ethers), ceteths (polyoxyethylene cetyl ethers), steareths (polyoxyethylene stearyl ethers), and beheneths (polyoxyethylene behenyl ethers), which can be used alone or in combination of two or more. Among these, the use of beheneth-30, ceteth-20, and laureth-21 is preferred in terms of their molecular structure and hydrophilicity.

[0017] The polymer dispersant may contain at least one selected from the group consisting of polyaspartic acid, polyglutamic acid, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and styrene-α-methylstyrene-acrylic acid copolymer, or one or more salts thereof. Examples of the salts include alkali salts such as sodium, potassium, and lithium salts, ammonium salts, and alkanolamine salts such as mono-, di-, and triethanolamine salts and triisopropanolamine salts. Among these polymer dispersants, polyaspartic acid, polyglutamic acid, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-α-methylstyrene-acrylic acid copolymer, and at least one of their salts are particularly preferred as they have excellent dispersion stability, and sodium polyaspartate (Na) is particularly preferred.

[0018] The content of these dispersants is preferably 0 to 5%, and more preferably 0 to 3%, of the entire liquid cosmetic (total amount). If the content of this dispersant exceeds 5%, it is not preferable because it will have a negative effect on the stability of the cosmetic.

[0019] The remainder of the dispersion is prepared with water (purified water, distilled water, ion-exchanged water, pure water, tap water, etc.). The Prussian blue dispersion for cosmetics of the present invention contains at least the above-mentioned Prussian blue, a water-soluble basic substance, and water. However, in order to further improve dispersibility and the dissolution stability of each component, a viscosity adjuster, a chelating agent, a dispersant, a pH adjuster, etc. may be appropriately used as needed.

[0020] The Prussian blue dispersion for cosmetics of the present invention can be prepared by blending the components containing at least the above-mentioned Prussian blue, the water-soluble basic substance, the dispersant, and water in the above-mentioned content ranges, and stirring and mixing the mixture uniformly. For example, the Prussian blue dispersion for cosmetics can be prepared by stirring the Prussian blue, the water-soluble basic substance, the dispersant, and a solvent such as water until the mixture is homogenous using a general-purpose disperser or the like, and then further stirring the mixture with a homomixer or the like until the mixture is homogenous using a disperser or the like, or by mixing and dispersing using various types of stirrers and dispersers such as a disperser, an ultrasonic disperser, a planetary mixer, a three-roll mill, a ball mill, a bead mill, and a jet mill. The optimum mixer and disperser are selected depending on the types and ratios of the ingredients, the viscosity of the dispersion liquid after stirring, etc. The dispersion conditions do not need to be specially set, and the dispersion can be carried out under known conditions (peripheral speed, time, etc.).

[0021] In the cosmetic Prussian blue dispersion of the present invention, the viscosity was measured at 25°C using a cone-plate viscometer, and the shear rate was 383 s -1 From the viewpoints of proper viscosity, dispersion stability of Prussian blue, improved blendability into cosmetics, and improved outflow from collector-type pen-type applicators, the viscosity of the emulsion is preferably 50 mPa·s or less, more preferably 10 mPa·s or less, even more preferably 2 to 8.5 mPa·s, and particularly preferably 2 to 6 mPa·s. The viscosity range (50 mPa·s or less) can be adjusted by appropriately adjusting the amount of each of the above components used, the type and amount of the above-mentioned preferably used dispersant, the type and amount of the pH adjuster, etc.

[0022] Furthermore, the Prussian blue dispersion for cosmetics used in the present invention has an average particle size of 200 nm or less, preferably 130 nm or less, and more preferably 80 to 130 nm, as determined by cumulant method analysis in the scattering intensity distribution of the dispersed Prussian blue. By making the average particle size of this Prussian blue 200 nm or less, preferably 130 nm or less, it is possible to achieve better dispersion stability and vivid color development. The lower the lower limit of the average particle size, the better, but from the viewpoints of manufacturability, cost, etc., it is preferable that it be 80 nm or more. In the present invention, examples of measuring devices include a dynamic light scattering method using an FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.), a laser diffraction / scattering method using a Microtrac (manufactured by Nikkiso Co., Ltd.), and an image imaging method using a MacView (manufactured by Mountec Co., Ltd.).

[0023] The Prussian blue cosmetic dispersion used in the present invention is preferably adjusted to a pH of 7.5 or less, more preferably 4 to 7.2, from the viewpoints of improving coloring properties, preventing skin irritation, and dispersion stability. In the present invention, the pH of the dispersion can be adjusted using an acidic substance such as citric acid or a basic substance such as 2-amino-2-methyl-1-propanol.

[0024] The pigment dispersion for cosmetics of the present invention, which is configured in this manner, contains at least Prussian blue, a water-soluble basic substance, and water, and thereby solves problems such as a decrease in the absolute value of the zeta potential of Prussian blue, aggregation, and discoloration, and can maintain the surface potential of the Prussian blue, dispersion stability, and microparticulation, thereby resulting in a Prussian blue dispersion for cosmetics that has excellent dispersion stability, color development (high saturation), and storage stability over time. Furthermore, the resulting Prussian blue dispersion for cosmetics of the present invention can be used as a new dispersion method for Prussian blue, which allows for the production of a highly saturated blue hue, and due to the improved microparticulation and dispersion stability, can be used in applicators for aqueous cosmetics such as direct-loading eyeliners.Furthermore, by using it in combination with a dispersion of red iron oxide or a yellow legal pigment, it is possible to obtain highly saturated green, pigment dispersions of various colors (increasing the variety of mixed colors), and cosmetics, and therefore it can be suitably used as a pigment component for aqueous cosmetics, etc.

[0025] The obtained Prussian blue cosmetic dispersion is suitable for use in cosmetics that use Prussian blue, compositions for body markers, and the like. Preferred uses for cosmetics include skin care cosmetics, makeup cosmetics, nail cosmetics, and the like, and examples thereof include makeup cosmetics such as foundation, eye shadow, eyeliner, eyebrows, mascara, blush, nail color, treatment nails, various gel nails, and lipstick, as well as hair color, and examples of body marker compositions include body paint, etc. There are also no particular limitations on the form of the product, but since it is a dispersion (aqueous), it can be applied to aqueous forms such as liquid, emulsion, cream, paste, gel, mousse, and spray. In particular, due to the dispersibility of the pigment dispersion for cosmetics of the present invention, it is preferably used in aqueous liquid cosmetics such as eye makeup cosmetics such as eye shadow, eye liner, eyebrow pencil, and mascara, and aqueous nail colors.

[0026] The cosmetic of the present invention is characterized by containing the above-mentioned Prussian blue dispersion for cosmetics, and various types of cosmetic can be prepared by blending the Prussian blue dispersion for cosmetics of the present invention with general-purpose ingredients for each application, such as skin care cosmetics, makeup cosmetics, and nail cosmetics. For example, when preparing an eyeliner as a cosmetic containing the Prussian blue cosmetic dispersion, the cosmetic contains at least 1 to 60% of the Prussian blue cosmetic dispersion, a solvent, a pH adjuster, and 5 to 30% of a film-forming agent. However, other raw materials such as solvents, thickeners, various surfactants other than those mentioned above (POE alkyl ethers), preservatives (phenoxy ethers, parabens), UV absorbers, antioxidants, anti-reducing agents, chelating agents, oily components, fragrances, animal and plant extracts, etc. may also be contained in appropriate amounts within the range that does not impair the effects of the present invention. In the present invention, the remainder (residue) of the cosmetic is adjusted with water (purified water, distilled water, ion-exchanged water, pure water, tap water, etc.).

[0027] When using the cosmetic of the present embodiment configured as described above, a general-purpose applicator used for eyeliner and the like can be used, and the shape, structure, etc. of the applicator to be used are not particularly limited, and examples include applicators equipped with a knock-type valve device, direct liquid type applicators equipped with a collector function, tube-type applicators, and applicators equipped with a piston pressing mechanism.

[0028] The cosmetic of the present embodiment, configured as described above, contains a cosmetic pigment dispersion containing at least the above-mentioned Prussian blue, a water-soluble basic substance, and water, as well as, for example, a film-forming agent, a pH adjuster, a dispersing (stabilizing) agent, and a preservative, and therefore has excellent dispersibility stability, color development (high saturation), and storage stability of Prussian blue.Therefore, it is possible to stably disperse the Prussian blue used in the cosmetic, and to obtain a cosmetic that has excellent dispersion stability, storage stability, ease of use, and application. [Example]

[0029] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0030] [Examples 1 to 9 and Comparative Examples 1 to 4] A Prussian blue dispersion for cosmetics was prepared using the formulation shown in Table 1 below and dispersion by the method described below. The obtained Prussian blue dispersion for cosmetics was evaluated for viscosity, pH, and average particle size by the methods described below, and the color development and storage stability of cosmetics using this Prussian blue dispersion for cosmetics were evaluated by the evaluation methods described below. The results are shown in Table 1 below.

[0031] (Distribution method) Using a general-purpose disperser, Prussian blue, basic substance, water, and optionally a dispersant were stirred and mixed in the formulation shown in Table 1 below, and the mixture was passed through a bead mill disperser (LMZ015: manufactured by Ashizawa Finetech Co., Ltd.) and the dispersion was carried out while adjusting the dispersion conditions (circumferential speed) while observing the dispersion state. In the table, the dispersion conditions (peripheral speed) are "medium" at 6 to 10 m / s and dispersion time at 30 to 300 minutes, and "strong" at "medium" or higher.

[0032] (pH measurement method) The pH at 25°C of each Prussian blue solution for cosmetics before dispersion and each Prussian blue dispersion for cosmetics obtained by the dispersion method described below was measured using a glass electrode pH meter. (Viscosity measurement method) The viscosity of each of the cosmetic Prussian blue dispersions obtained by the above method was measured at 25°C using a cone-plate viscometer (TVE-25, manufactured by Toki Sangyo Co., Ltd.). The shear rate was 383 s -1 The viscosity was measured under the following conditions. (Method for measuring average particle size) The average particle size was measured by dynamic light scattering using FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.).

[0033] (Method for evaluating color development) Cosmetics were prepared using each of the obtained Prussian blue cosmetic dispersions, adding a solvent (1,3-butylene glycol), a pH adjuster (2-amino-2-methyl-1-propanol), a preservative (phenoxy ether, parabens), a film-forming resin (aqueous emulsion), and water (purified water). The cosmetics were filled into Mitsubishi Pencil Co., Ltd. UC-76B containers, and the color development was evaluated according to the following evaluation criteria. Evaluation criteria: ◯: Easy to discharge from the container and good color development. △: The product was not easily discharged from the container and the color was not very good. ×: Less discharge from the container and poor color development.

[0034] (Method for evaluating storage stability) Cosmetics were prepared for each of the obtained Prussian blue cosmetic dispersions in the same manner as in the evaluation of color development described above, filled into Mitsubishi Pencil Co., Ltd. UC-76B containers, and evaluated for storage stability according to the following evaluation criteria. Storage stability evaluation criteria: ○: There is little settling of the pigment during storage, and the difference in concentration from the initial level is not large. △: There is considerable settling of pigment during storage, and the concentration differs greatly from the initial concentration. ×: The cosmetic material was poorly discharged and was difficult to use.

[0035] [Table 1]

[0036] The results in Table 1 above reveal that Examples 1 to 9, which fall within the scope of the present invention, are superior in color development and storage stability to Comparative Examples 1 to 4, which fall outside the scope of the present invention. In contrast, Comparative Examples 1 to 4 did not contain any water-soluble basic substance, and only Comparative Example 4 further contained a dispersant. However, Comparative Examples 1 and 2 had poor storage stability, and Comparative Examples 3 and 4 thickened (gelled) and could not be microparticulated. Looking at the results of Examples 1 to 9 above, it was surprisingly confirmed that the dispersion state was stable even when the pH of the dispersion was basic, and the average particle size itself could be micronized to approximately 100 nm to 200 nm (preferably 130 nm or less), and that the color development and storage stability were excellent.

[0037] Furthermore, when each of the cosmetics obtained in Examples 1 to 4, 7, and 9 above was placed in a cosmetic applicator (applicator configuration: applicator part; brush tip, equipped with collector function, UC-76C; manufactured by Mitsubishi Pencil Co., Ltd.) and applied to the eyelids, it was confirmed that despite the low viscosity, the cosmetics did not smudge, and even though extremely thin lines could be drawn, they were a vivid blue color and were clearly defined. [Industrial Applicability]

[0038] A Prussian blue dispersion for cosmetics having excellent dispersion stability, color development (high saturation) and storage stability can be obtained, and by using this Prussian blue dispersion, cosmetics suitable for base makeup cosmetics such as foundation and under makeup, point makeup cosmetics such as eye shadow, eyeliner, mascara, eyebrow pencil, and nail color can be obtained, which have unprecedented color development (high saturation) and excellent storage stability.

Claims

1. A cosmetic Prussian blue dispersion comprising Prussian blue, a water-soluble basic substance, and water.

2. A cosmetic Prussian blue dispersion comprising Prussian blue, a water-soluble basic substance, water, and a nonionic surfactant.

3. 3. The Prussian blue dispersion for cosmetics according to claim 1, wherein the water-soluble basic substance is contained in an amount ranging from 0.025 to 0.25 when the Prussian blue content is taken as 1 in terms of mass ratio.

4. 4. The Prussian blue dispersion for cosmetics according to claim 1, wherein the water-soluble basic substance is at least one selected from the group consisting of ammonia, a compound having an amino group, and an alkali metal hydroxide.

5. When viscosity was measured using a cone-plate viscometer at 25°C, the shear rate was 383 s －１ 5. The Prussian blue dispersion for cosmetics according to claim 1, wherein the viscosity of the dispersion is 50 mPa·s or less.

6. The Prussian blue dispersion for cosmetics according to any one of claims 1 to 5, characterized in that the Prussian blue has an average particle size of 200 nm or less in a scattering intensity distribution determined by a cumulant method analysis.

7. a step of producing a cosmetic Prussian blue dispersion comprising Prussian blue, a water-soluble basic substance, and water; Next, the method for producing a cosmetic comprises the step of producing a cosmetic containing the Prussian blue dispersion for cosmetics, and at least a solvent, a pH adjuster, and a film-forming agent.

8. A step of producing a Prussian blue dispersion for cosmetics comprising Prussian blue, a water-soluble basic substance, water, and a nonionic surfactant; Next, the method for producing a cosmetic comprises the step of producing a cosmetic containing the Prussian blue dispersion for cosmetics, and at least a solvent, a pH adjuster, and a film-forming agent.

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