Cellulose particle and cosmetic of cellulose particle

Abstract

To provide cellulose particles having excellent hydrophobicity and dispersibility.SOLUTION: Cellulose particles include: mother particles, containing cellulose as a principal component; and a coating layer that coats the mother particles, where the average circularity of the cellulose particles is 0.97 or more, and the relationship between carbon atom amount Cs and oxygen atom amount Os, measured by X-ray photoelectron spectroscopy, satisfies the formula A1: Cs / Os≥2.0.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to cellulose particles and cosmetics. [Background technology]

[0002] Patent Document 1 proposes "resin beads obtained by surface-treating core beads formed of a resin whose main component is cellulose with a solid surface treatment agent, the resin beads having a volume-based cumulative 50% particle size of 50 μm or less, a sphericity of 0.7 to 1.0, a surface smoothness of 70 to 100%, and a crystallinity of 60% or less."

[0003] Patent Document 2 proposes "particles containing cellulose acetate, the particles having an average particle diameter of 80 nm or more and 100 μm or less, a sphericity of 0.7 or more and 1.0 or less, a surface smoothness of 80% or more and 100% or less, and a surface contact angle with water of 100° or more, and a total acetyl substitution degree of the cellulose acetate of 0.7 or more and 2.9 or less."

[0004] Patent Document 3 proposes "biodegradable resin particles having a base particle containing a biodegradable resin, a first layer having on the surface of the base particle the first layer containing at least one cationic resin selected from polyalkyleneimine, polyallylamine and polyvinylamine, and a second layer having on the first layer the second layer containing an anionic or nonionic hydrophobic compound." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6921293 [Patent Document 2] Patent No. 6694559 [Patent Document 3] Patent Publication No. 2022-22947 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide cellulose particles having base particles mainly composed of cellulose and a coating layer covering the base particles, the cellulose particles having a circularity of less than 0.97 and excellent hydrophobicity and dispersibility compared to cellulose particles in which the relationship between the carbon atom amount Cs and the oxygen atom amount Os measured by X-ray photoelectron spectroscopy does not satisfy the formula A1:Cs / Os≧2.0. [Means for solving the problem]

[0007] Means for solving the above problems include the following aspects. <1> A base particle mainly composed of cellulose; a coating layer that coats the base particles; having The average circularity is 0.97 or more, Cellulose particles in which the relationship between the amount of carbon atoms Cs and the amount of oxygen atoms Os, as measured by X-ray photoelectron spectroscopy, satisfies the formula A1: Cs / Os≧2.0. <2> The relationship between the carbon atom amount Cs and the oxygen atom amount Os satisfies formula A2: Cs / Os≧4.0. <1> The cellulose particles according to claim 1. <3> The coating layer contains at least one coating material selected from the group consisting of fatty acids, fatty acid metal salts, amino acids, and amino acid salts. <1> or <2> The cellulose particles according to claim 1. <4> The amount of the coating layer relative to the base particles is 2% by mass or more and 30% by mass or less. <1> ~ <3> The cellulose particles according to any one of claims 1 to 5. <5> The amount of the coating layer relative to the base particles is 4% by mass or more and 15% by mass or less. <4> The cellulose particles according to claim 1. <6> An intermediate layer is provided between the base particles and the coating layer. <1> ~ <5> The cellulose particles according to any one of claims 1 to 5. <7> The intermediate layer contains at least one intermediate material selected from the group consisting of a polyamine compound, a polyquaternium, a polysaccharide compound, and a polyacrylic acid. <6> The cellulose particles according to claim 1. <8> <1> ~ <7> A cosmetic comprising the cellulose particles according to any one of claims 1 to 5. Effect of the Invention

[0008] <1> According to the present invention, there is provided cellulose particles having a base particle mainly composed of cellulose and a coating layer covering the base particle, the cellulose particles having a circularity of less than 0.97 and excellent hydrophobicity and dispersibility compared to cellulose particles in which the relationship between the carbon atom amount Cs and the oxygen atom amount Os measured by X-ray photoelectron spectroscopy does not satisfy the formula A1:Cs / Os≧2.0. <2> According to the invention, cellulose particles having excellent hydrophobicity and dispersibility are provided, as compared with those in which the relationship between the carbon atom amount Cs and the oxygen atom amount Os does not satisfy the formula A2: Cs / Os≧4.0. <3> According to the present invention, there are provided cellulose particles which are superior in hydrophobicity and dispersibility as compared with the case where the coating layer contains stearyl stearate. <4> According to the present invention, cellulose particles having excellent hydrophobicity and dispersibility are provided, as compared with the case where the amount of the coating layer relative to the base particles is less than 2% by mass or more than 30% by mass. <5> According to the present invention, cellulose particles having excellent hydrophobicity and dispersibility are provided, as compared with the case where the amount of the coating layer relative to the base particles is less than 4% by mass or more than 15% by mass. <6> According to the present invention, there are provided cellulose particles which are excellent in hydrophobicity and dispersibility compared to the case where no intermediate layer is provided between the base particles and the coating layer. <7> According to the present invention, cellulose particles having superior hydrophobicity and dispersibility are provided as compared with the case where the intermediate layer contains carbomer. <8> According to the invention, there is provided a cosmetic product which is excellent in sweat resistance and smearing resistance compared to the case where cellulose particles having a circularity of less than 0.97 and a relationship between the amount of carbon atoms Cs and the amount of oxygen atoms Os, as measured by X-ray photoelectron spectroscopy, does not satisfy the formula A1:Cs / Os≧2.0, are used, the cosmetic product having such excellent sweat resistance and smearing resistance compared to the case where cellulose particles having a circularity of less than 0.97 and a relationship between the amount of carbon atoms Cs and the amount of oxygen atoms Os, as measured by X-ray photoelectron spectroscopy, does not satisfy the formula A1:Cs / Os≧2.0 are used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described as an example. The description and examples are merely illustrative of the embodiment, and are not intended to limit the scope of the present invention. In the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples.

[0010] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if the composition contains multiple substances corresponding to each component, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0011] <Cellulose particles> The cellulose particles according to this embodiment have base particles containing cellulose as a main component, and a coating layer that coats the base particles. The cellulose particles according to this embodiment have an average circularity of 0.97 or more, and the relationship between the carbon atom amount Cs and the oxygen atom amount Os measured by X-ray photoelectron spectroscopy satisfies the formula A1: Cs / Os≧2.0.

[0012] The cellulose particles according to the present embodiment have the above-mentioned configuration, and are excellent in hydrophobicity and dispersibility. The reason for this is presumed to be as follows.

[0013] By setting the ratio (Cs / Os) of the carbon atom amount Cs to the oxygen atom amount Os in the cellulose particles to 2.0, the number of carbon atoms present on the particle surface increases, enhancing hydrophobicity. On the other hand, by making the average circularity of the cellulose particles, which are formed by forming a coating layer on the base particles mainly composed of cellulose, 0.97 or more, the particles become closer to a perfect sphere, improving the rolling property and therefore the dispersibility.

[0014] From the above, it is presumed that the cellulose particles according to this embodiment have excellent hydrophobicity and dispersibility. In particular, since the cellulose particles according to this embodiment have excellent hydrophobicity and dispersibility, when applied to cosmetics, cosmetics having excellent sweat resistance and smearing resistance can be obtained. The term "makeup smearing" refers to a phenomenon in which cosmetics applied to the skin gather together in parts over time, appearing, for example, in lines.

[0015] (Relationship between carbon atom weight Cs and oxygen atom weight Os) In the cellulose particles according to this embodiment, the relationship between the carbon atom amount Cs and the oxygen atom amount Os measured by X-ray photoelectron spectroscopy satisfies the following formula A1, preferably satisfies the following formula A2, and more preferably satisfies the following formula A3. Formula A1: Cs / Os≧2.0 Formula A2: Cs / Os≧4.0 Formula A3: Cs / Os≧5.0 However, the upper limit of the ratio Cs / Os is, for example, 20 or less.

[0016] When the relationship between the carbon atom amount Cs and the oxygen atom amount Os satisfies formula A1, that is, when the ratio Cs / Os is 2.0 or more, the amount of carbon atoms exposed on the surface of the cellulose particles increases, improving hydrophobicity.

[0017] As a method for adjusting the ratio Cs / Os to fall within the above range, a method in which the surface treatment with a coating material containing carbon is carried out in multiple steps to form a coating layer can be mentioned.

[0018] In the cellulose particles according to this embodiment, the relationship between the carbon atom amount Cs and the silicon atom amount Sis measured by X-ray photoelectron spectroscopy preferably satisfies the following formula B. In other words, the silicon atom amount Sis is preferably 0 atom % or a small amount. Formula B: 0≦Sis / Os≦0.01 By increasing the hydrophobicity of the surface of cellulose particles using carbon atoms rather than silicon atoms, the surface free energy is further reduced, which has the advantage of further increasing resistance to makeup smudging caused by sweat, sebum, etc.

[0019] -Measuring atomic weights using X-ray photoelectron spectroscopy- The method for measuring each atomic weight (atom%) by X-ray photoelectron spectroscopy (XPS) is as follows. The measurement is performed on cellulose particles. The XPS measurement device used is an ULVAC-PHI PHI5000 Versa Probe II, and the measurement is performed using monochromatic AlKα radiation as the X-ray source and an acceleration voltage of 15 kV. Specifically, the analysis area is set to 100 μmφ, and the number of each atom (carbon atom, silicon atom, and oxygen atom) is calculated based on the spectrum of each measured atom (carbon atom, silicon atom, and oxygen atom), and the weight of each atom (carbon atom weight, silicon atom weight, and oxygen atom weight) relative to the total atomic weight in the measurement area is calculated.

[0020] The amounts of carbon atoms, silicon atoms and oxygen atoms measured on the surface of the cellulose particles are calculated as the amount of carbon atoms Cs, the amount of silicon atoms Sis and the amount of oxygen atoms Os. However, when the compound contained in the coating layer does not contain silicon atoms, the amount of silicon atoms is 0 atom %.

[0021] (Average circularity) The average circularity of the cellulose particles according to this embodiment is 0.97 or more, and from the viewpoint of improving hydrophobicity and dispersibility, it is preferably 0.98 or more, and more preferably 0.99 or more. The average circularity of the cellulose particles is ideally 1.

[0022] As a method for adjusting the average circularity to be within the above range, there may be mentioned a method in which the surface treatment with a coating material is carried out in several separate steps to form a coating layer.

[0023] The circularity of a cellulose particle is calculated by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)]. Specifically, it is a value measured by the following method. First, the cellulose particles to be measured are sucked and collected, flattened, and a still image is captured by instantaneous strobe light emission, and the particle image is analyzed using a flow-type particle image analyzer (FPIA-3000, manufactured by Sysmex Corporation). The number of samples to be sampled when calculating the circularity is 3500, and the arithmetic average is calculated to obtain the average circularity.

[0024] (base particle) The base particles are particles on which a coating layer is to be formed, and contain cellulose as a main component. Here, "containing cellulose as a main component" means that the content of cellulose in the base particle is 90% by mass or more (preferably 95% by mass or more, 98% by mass or more, or 100% by mass).

[0025] The number average molecular weight of the cellulose is preferably 37,000 or more, and more preferably 45,000 or more. The upper limit of the number average molecular weight of the cellulose is not particularly limited, but may be, for example, 100,000 or less.

[0026] The number average molecular weight of cellulose was measured by gel permeation chromatography (differential refractometer Optilab T-rEX / Wyatt Technology, multi-angle light scattering detector) The measurement is performed using a DAWN HELEOS II (Wyatt Technology) and columns (TSKgel α-M, α-3000, Tosoh) in dimethylacetamide (with 0.1M lithium chloride added) as the solvent.

[0027] -Other ingredients- The base particles may contain other components. Examples of other components include plasticizers, flame retardants, compatibilizers, release agents, light resistance agents, weather resistance agents, colorants, pigments, modifiers, anti-drip agents, antistatic agents, hydrolysis inhibitors, fillers, reinforcing agents (glass fibers, carbon fibers, talc, clay, mica, glass flakes, milled glass, glass beads, crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, etc.), acid acceptors for preventing release of acetic acid (oxides such as magnesium oxide and aluminum oxide; metal hydroxides such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, and hydrotalcite; calcium carbonate; talc; etc.), and reactive trapping agents (for example, epoxy compounds, acid anhydride compounds, carbodiimides, etc.). The content of each of the other components is preferably 0% by mass or more and 5% by mass or less based on the total amount of the base particles, where "0% by mass" means that no other components are included.

[0028] (covering layer) The coating layer preferably contains a coating material selected from hydrophobic compounds. Specifically, the coating layer preferably contains a coating material selected from compounds having a carboxyl group, and more preferably contains at least one coating material selected from the group consisting of fatty acids, fatty acid metal salts, amino acids, and amino acid metal salts, and more preferably contains at least one coating material selected from the group consisting of fatty acid metal salts and amino acid metal salts. These coating materials (particularly metal salts) have a ratio Cs / Os within the above range, which increases the hydrophobicity of the coating layer, and also increases the circularity and improves dispersibility. It is preferable that the coating layer does not contain a Si-containing compound as a coating material, or if it does contain one, the amount of the Si-containing compound is 1 mass % or less relative to the coating layer.

[0029] -fatty acid- The fatty acids are linear or branched, saturated or unsaturated fatty acids. The fatty acids may also be mixtures of saturated and unsaturated fatty acids. The fatty acid is preferably a fatty acid having 14 to 22 carbon atoms (preferably 14 to 20 carbon atoms). Specific examples of linear fatty acids having 14 to 22 carbon atoms include behenic acid, arachidic acid, palmitic acid, stearic acid, isostearic acid, and myristic acid.

[0030] -Fatty acid metal salts- The fatty acid metal salt is a metal salt of a linear or branched, saturated or unsaturated fatty acid. The fatty acid metal salt may be a mixture of a saturated fatty acid metal salt and an unsaturated fatty acid metal salt. Examples of the fatty acid metal salt include metal salts of fatty acids having 14 to 22 carbon atoms (preferably 14 to 20 carbon atoms). Examples of the metal salts of fatty acids having 14 to 22 carbon atoms include metal salts of stearic acid, behenic acid, palmitic acid, myristic acid, etc. The metal in the fatty acid metal salt includes a divalent or higher metal. Examples of metals in fatty acid metal salts include magnesium, calcium, aluminum, barium, and zinc.

[0031] -amino acid- The amino acid may be an amino acid having 12 to 30 carbon atoms (preferably 18 to 24 carbon atoms). Specific examples of amino acids include lauroyl lysine, lauryl arginine, myristyl leucine, and stearoyl glutamic acid.

[0032] -Amino acid metal salts- The amino acid metal salts include metal salts of amino acids having 12 to 30 carbon atoms (preferably 18 to 24 carbon atoms). Specific examples of amino acids include metal salts of lauroyl lysine, lauryl arginine, myristyl leucine, stearoyl glutamic acid, and the like. The metal in the amino acid metal salt includes a divalent or higher metal. Examples of the metal in the amino acid metal salt include magnesium, calcium, aluminum, barium, and zinc.

[0033] From the viewpoint of improving hydrophobicity and dispersibility, the amount of the coating layer on the base particles is preferably from 2 to 30% by mass, more preferably from 4 to 15% by mass, and even more preferably from 10 to 30% by mass. Here, the content of the coating material in the entire coating layer is preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less.

[0034] -Middle class- In the cellulose particles according to the present embodiment, it is preferable to have an intermediate layer between the base particle and the coating layer. When the intermediate layer is provided, carbon atoms are oriented on the surface of the coating layer, the ratio Cs / Os is easily within the above range, and hydrophobicity is enhanced.

[0035] The intermediate layer preferably contains at least one intermediate material selected from the group consisting of a polyamine compound, a polyquaternium, a polysaccharide compound, and a polyacrylic acid.

[0036] A polyamine compound is a general term for an aliphatic hydrocarbon having two or more primary amino groups. Examples of the polyamine compound include polyalkyleneimine, polyallylamine, polyvinylamine, and polylysine. From the viewpoint of improving biodegradability, the polyalkyleneimine is preferably a polyalkyleneimine having a structural unit with an alkylene group having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms), and more preferably polyethyleneimine. Examples of polyallylamine include homopolymers or copolymers of allylamine, allylamine amide sulfate, diallylamine, dimethylallylamine, and the like. An example of the polyvinylamine is one produced by hydrolyzing poly(N-vinylformamide) with an alkali, and a specific example is "PVAM-0595B" manufactured by Mitsubishi Chemical Corporation. The polylysine may be one extracted from a natural product, one produced by a transformed microorganism, or one chemically synthesized.

[0037] Examples of polyquaterniums include polyquaternium-6, polyquaternium-7, polyquaternium-10, polyquaternium-11, polyquaternium-51, polyquaternium-61, and polyquaternium-64. The content of the polyquaternium is preferably 0.2% by mass or more and 2% by mass or less based on the total mass of the cellulose particles.

[0038] Examples of polysaccharide compounds include chitin, chitosan, carboxymethylcellulose, etc. Examples of polysaccharide compounds include polysaccharides having sulfate or phosphoric acid, polysaccharides having uronic acid (e.g., glucuronic acid, iduronic acid, galacturonic acid, mannuronic acid), or polysaccharides having both of these acid structures. Specifically, examples of polysaccharides include hyaluronic acid, gellan gum, deacylated gellan gum (DAG), rhamsan gum, diutan gum, xanthan gum, carrageenan, xanthan gum, hexuronic acid, fucoidan, pectin, pectic acid, pectinic acid, heparan sulfate, heparin, heparitin sulfate, keratosulfate, chondroitin sulfate, dermatan sulfate, rhamnan sulfate, and alginic acid.

[0039] The coverage of the intermediate layer on the base particles is preferably from 0.1% by mass to 20% by mass, more preferably from 0.2% by mass to 2% by mass, from the viewpoint of improving hydrophobicity and dispersibility. The content of the intermediate material in the entire intermediate layer is preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less.

[0040] The ratio of the coating amount of the coating layer to the coating amount of the intermediate layer (i.e., ratio = coating amount of coating layer / coating amount of intermediate layer) is preferably 0.05 or more and 400 or less, more preferably 1.5 or more and 150 or less, and even more preferably 5 or more and 150 or less, from the viewpoint of improving hydrophobicity and dispersibility.

[0041] -External additives- The cellulose particles according to the present embodiment may contain inorganic particles. When inorganic particles are added, secondary aggregation between particles is suppressed, and the particles are more likely to exhibit their inherent properties. Therefore, hydrophobicity and dispersibility are more likely to be improved.

[0042] The external additive may be at least one selected from the group consisting of silicon-containing compound particles and metal oxide particles.

[0043] The silicon-containing compound particles refer to particles that contain silicon. The silicon-containing compound particles may be particles containing only silicon, or may be particles containing silicon and other elements.

[0044] The silicon-containing compound particles are preferably silica particles. The silica particles may be crystalline or amorphous as long as they are particles that are mainly composed of silica, i.e., SiO2. The silica particles may be particles manufactured from silicon compounds such as water glass and alkoxysilane as raw materials, or may be particles obtained by crushing quartz. As the metal oxide, oxides of metals other than silicon can be used. Examples of metal oxides include zinc oxide, magnesium oxide, iron oxide, and aluminum oxide.

[0045] The volume average particle size of the external additive is preferably from 1 nm to 100 nm, more preferably from 5 nm to 30 nm, from the viewpoint of texture (specifically, feel on the skin). The volume average particle diameter of the external additive is measured in the same manner as the volume average particle diameter of the cellulose.

[0046] The amount of the external additive added is preferably 0.1% by mass or more and 2% by mass or less with respect to the total mass of the cellulose particles (cellulose particles to which no external additive has been added).

[0047] (Volume average particle size) The volume average particle size of the cellulose particles according to this embodiment is preferably from 1 μm to 100 μm, more preferably from 2 μm to 20 μm, and further preferably from 4 μm to 10 μm. By adjusting the volume average particle size of the cellulose particles according to this embodiment to be 1 μm or more and 100 μm or less, the particle size becomes appropriate, and the hydrophobicity and dispersibility are improved.

[0048] The volume average particle size of the cellulose particles is measured as follows. The particle size is measured using an LS particle size distribution analyzer "Beckman Coulter LS13 320 (manufactured by Beckman Coulter)" and the cumulative particle size distribution is plotted from the smallest diameter side on a volume basis. The particle size at 50% of the cumulative distribution is determined as the volume average particle size.

[0049] <Method of manufacturing cellulose particles> The method for producing cellulose particles according to this embodiment includes, for example, a step of obtaining base particles mainly composed of cellulose (hereinafter referred to as the "cellulose particle (base particle) production step") and a step of coating the base particles with a coating material and, if necessary, an intermediate material (hereinafter referred to as the "intermediate layer and coating layer formation step"). Specifically, the method for producing cellulose particles according to this embodiment is, for example, as follows. -Mother particle manufacturing process- (1) First, cellulose acylate is dissolved in a water-soluble organic solvent A to prepare a cellulose acylate solution A. (2) Next, the cellulose acylate solution A is added to a calcium carbonate dispersion obtained by dispersing calcium carbonate in water, and the mixture is stirred to prepare a cellulose acylate solution B. (3) Next, the cellulose acylate solution B is added to a mixed solution of carboxymethyl cellulose, the water-soluble organic solvent B, and water, and the mixture is stirred at high speed to prepare a cellulose acylate solution C. (4) Next, sodium hydroxide is added to the cellulose acylate solution C, and then the cellulose acylate dispersion C is heated to remove the water-soluble organic solvents A and B, and hydrochloric acid is added to form cellulose acylate particles. The cellulose acylate particles are then filtered, and the filtered cellulose acylate particles are dispersed in water to prepare a cellulose acylate particle dispersion. (5) Next, sodium hydroxide is added to the cellulose acylate particle dispersion, and the cellulose acylate particle dispersion is heated and stirred in a weak alkaline environment to saponify the cellulose acylate particles, thereby preparing a base particle suspension. (6) Next, hydrochloric acid is added to the base particle suspension to adjust the pH of the suspension to near neutral (for example, in the range of 6.5 to 7), and then the base particles are filtered and washed with pure water repeatedly. Then, after the electrical conductivity of the filtrate reaches 10 μs / cm or less, the filtered base particles are dried.

[0050] Here, cellulose acylate is a cellulose derivative in which at least one hydroxyl group in cellulose is substituted (acylated) with an aliphatic acyl group. AC (R AC represents an aliphatic hydrocarbon group. The water-soluble organic solvent A is a solvent in which 0.1% by mass to 10% by mass of water is dissolved at 25° C., and examples thereof include ethyl acetate and butyl acetate. The water-soluble organic solvent B is a solvent in which 0.1% by mass to 10% by mass of water is dissolved at 25° C., and examples thereof include methyl ethyl ketone and acetone.

[0051] - Intermediate layer and covering layer formation process - First, an aqueous dispersion of the base particles is prepared. Before preparing the aqueous dispersion, it is preferable to wash the base particles with an acid.

[0052] Next, the aqueous dispersion in which the base particles are dispersed is mixed with an aqueous solution containing an intermediate material that constitutes the intermediate layer. As a result, for example, the hydroxyl groups of the cellulose contained in the base particles react with the amine sites, carboxyl groups, amino groups, etc. of the compound that constitutes the intermediate layer, or the hydroxyl groups form hydrogen bonds, thereby forming the intermediate layer. It is preferable to carry out the operation of forming the intermediate layer multiple times. However, if no intermediate layer is formed, this operation is not carried out.

[0053] Then, after heating the aqueous dispersion in which the base particles on which the intermediate layer is formed are dispersed, the coating material constituting the coating layer is added and stirred. This forms the coating layer. It is preferable to carry out the operation of forming the coating layer several times. Here, when forming the coating layer, the coating amount of the coating layer is controlled by the heating temperature, the amount of coating material added, the addition time of the coating material, and the stirring time after the addition of the coating material.

[0054] The base particles with the coating layer formed thereon are then taken out from the mixed solution. The base particles with the coating layer formed thereon are taken out, for example, by filtering the mixed solution. The base particles with the coating layer formed thereon that have been taken out are preferably washed with water. This makes it possible to remove unreacted intermediate material and coating material. The base particles with the coating layer formed thereon are then dried to obtain the cellulose particles according to this embodiment.

[0055] -External addition process- An external additive may be added to the obtained cellulose particles. The external addition step may be, for example, a process in which an external additive is added to cellulose particles using a mixing mill, a V-type blender, a Henschel mixer, a Loedige mixer, or the like.

[0056] <Application> Applications of the cellulose particles according to this embodiment include granular materials such as cosmetics, rolling agents, abrasives, scrubbing agents, display spacers, materials for forming beads, light diffusing particles, resin reinforcing agents, refractive index control agents, biodegradation promoters, fertilizers, water absorbing particles, toner particles, and anti-blocking particles.

[0057] <Cosmetics> The cosmetic product according to this embodiment is a cosmetic product containing the cellulose particles according to this embodiment.

[0058] Examples of cosmetics according to the present embodiment include base makeup cosmetics (e.g., makeup base, concealer, foundation, face powder, etc.); makeup cosmetics (e.g., lipstick, gloss, lip liner, blush, eye shadow, eyeliner, mascara, eyebrows, nails, nail care cosmetics, etc.); skin care cosmetics (e.g., facial cleanser, cleansing, lotion, milky lotion, serum, pack, face mask, eye and mouth care cosmetics, etc.); and the like. In particular, the cosmetic product according to this embodiment is preferably a makeup cosmetic product since it has high sweat resistance and resistance to makeup smudging. EXAMPLES

[0059] Examples will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, all "parts" and "%" are based on mass.

[0060] <Preparing each ingredient> The following materials were prepared:

[0061] <Examples 1 to 17 and Comparative Examples 1 to 3> - Formation of mother particles - 130 parts of cellulose acylate (DAC "L-50" manufactured by Daicel Corporation, cellulose diacetate, weight average degree of polymerization 570) was completely dissolved in 870 parts of ethyl acetate. This was added to a dispersion in which 50 parts of calcium carbonate was dispersed in 500 parts of pure water, and the mixture was stirred for 3 hours. This was added to a dispersion in which 4 parts of carboxymethylcellulose and 200 parts of methyl ethyl ketone were dispersed in 600 parts of pure water, and the mixture was stirred for 5 minutes with a high-speed emulsifier. 10 parts of sodium hydroxide was added to this, and the mixture was stirred at 80°C for 3 hours to remove ethyl acetate and methyl ethyl ketone. 10 parts of dilute hydrochloric acid was added to this to dissolve calcium carbonate. The residue was filtered and dispersed again in pure water to obtain a slurry of cellulose acylate particles. 17.5 parts of 20% sodium hydroxide aqueous solution was added to 500 parts of cellulose acylate particle slurry (solid content 10%), and the mixture was stirred at 30°C for 6 hours to saponify the cellulose acylate particles. Hydrochloric acid was added dropwise to the slurry until the pH of the slurry became 7. The slurry was then filtered, and the filtered product was washed with an excess amount of pure water, and the filtering and washing were repeated until the electrical conductivity of the filtrate became 10 μs / cm or less. Finally, the obtained cake-like filtered product was filtered, and the filtered product was freeze-dried to obtain saponified cellulose mother particles.

[0062] -Surface treatment- The cake-like cellulose base particles, which had been repeatedly filtered and washed until the electrical conductivity of the filtrate reached 10 μs / cm or less, were reslurried in pure water to obtain a base particle slurry. To 500 parts of base particle slurry (solid content 10%), the type and amount of intermediate material shown in Table 1 was added, and while maintaining the temperature at 35° C., stirring was continued for the stirring time shown in Table 1. This treatment was carried out the number of times shown in Table 1 (number of treatments in the table). As a result, an intermediate layer with the coating amount shown in Table 1 was formed on the base particles. Next, the base particle slurry on which the intermediate layer was formed was heated to a temperature of 80° C., and the type and amount of coating material shown in Table 1 was added, followed by stirring for the stirring time shown in Table 1. This treatment was carried out the number of times shown in Table 1 (number of treatments in the table). As a result, a coating layer with the coating amount shown in Table 1 was formed on the intermediate layer. Thereafter, the base particles on which the intermediate layer and the coating layer were formed were repeatedly filtered and washed until the filtrate had an electric conductivity of 10 μs / cm or less. After washing, the resulting cake was dried to obtain cellulose particles having an intermediate layer and a coating layer. The obtained particles were mixed in an FM mixer (FM40, manufactured by Nippon Coke and Engineering Co., Ltd.) for 4000 min while maintaining the mixer temperature at 25°C. -1 The mixture was stirred at a rotation speed of 1000 for 2 hours to tan the surface of the coating layer.

[0063] In addition, as indicated by "-" in Table 1, in some cases, cellulose particles were prepared without forming an intermediate layer, or without forming an intermediate layer and a coating layer.

[0064] <Comparative Examples 4 to 5> The following commercially available cellulose particles were used as the cellulose particles of Comparative Examples 4 and 5, respectively. Comparative example 4: Daito Kasei Kogyo Co., Ltd. “S-STM CELLULOBEADS D-5” Comparative example 5: Daito Kasei Kogyo Co., Ltd. “OTS-0.5A CELLULOBEADS D-10”

[0065] <Evaluation> (Particle properties) For the cellulose particles obtained in each example, the following particle properties were measured according to the methods described above. The ratio of the atomic weight of carbon atoms, Cs, to the atomic weight of oxygen, Os (Cs / Os), measured by X-ray photoelectron spectroscopy Average circularity Volume average particle size of cellulose particles (referred to as "particle size" in the table)

[0066] (Artificial sweat contact angle) Using the cellulose particles of each example, a liquid foundation was obtained according to the formulation shown in Table 2 by a known method. A liquid foundation was applied to the artificial skin and left to stand at room temperature for 1 hour. Artificial sweat was dropped onto the artificial skin using a contact angle measuring device, and the contact angle of the artificial sweat was measured. The evaluation criteria were as follows: A:100°≦Contact angle B:90°≦Contact angle≦100° C: Contact angle <90°

[0067] (Makeup smudged) Using the cellulose particles of each example, a liquid foundation was obtained according to the formulation shown in Table 2 by a known method. Ten test subjects were asked to apply 5g of liquid foundation to the back of their hands, spread it, and after 8 hours, rate the degree of makeup smudging on a 10-point scale, with 10 being the best and 0 being the worst. The scores of the 10 test subjects were then averaged to evaluate the results.

[0068] [Table 1-1]

[0069] [Table 1-2]

[0070] [Table 2]

[0071] From the above results, it is apparent that the cellulose particles of this Example are superior in sweat resistance and makeup smudging resistance to the cellulose particles of the Comparative Example. This also shows that the cellulose particles of this example are superior in hydrophobicity and dispersibility to the cellulose particles of the comparative example.

[0072] The present embodiment includes the following aspects. (((1))) A base particle mainly composed of cellulose; a coating layer that coats the base particles; having The average circularity is 0.97 or more, Cellulose particles in which the relationship between the amount of carbon atoms Cs and the amount of oxygen atoms Os, as measured by X-ray photoelectron spectroscopy, satisfies the formula A1: Cs / Os≧2.0. (((2))) The cellulose particles according to (((1))), wherein the relationship between the carbon atom amount Cs and the oxygen atom amount Os satisfies formula A2: Cs / Os≧4.0. (((3))) The cellulose particles according to (((1))) or (((2))), wherein the coating layer comprises at least one coating material selected from the group consisting of fatty acids, fatty acid metal salts, amino acids, and amino acid salts. (((4))) The cellulose particles according to any one of ((1))) to (((3))), wherein the amount of the coating layer relative to the base particles is 2% by mass or more and 30% by mass or less. (((5))) The cellulose particles according to (((4))), wherein the amount of the coating layer relative to the base particles is 4% by mass or more and 15% by mass or less. (((6))) The cellulose particles according to any one of ((1))) to (((5))), which have an intermediate layer between the base particle and the coating layer. (((7))) The cellulose particles according to (((6))), wherein the intermediate layer contains at least one intermediate material selected from the group consisting of polyamine compounds, polyquaterniums, polysaccharide compounds, and polyacrylic acids. (((8))) A cosmetic comprising the cellulose particles according to any one of (((1))) to (((7))).

[0073] The advantages of the above aspect are as follows. According to the invention of (((1))), there is provided cellulose particles having base particles mainly composed of cellulose and a coating layer covering the base particles, the cellulose particles having a circularity of less than 0.97 and excellent hydrophobicity and dispersibility compared to cellulose particles in which the relationship between the carbon atom amount Cs and the oxygen atom amount Os measured by X-ray photoelectron spectroscopy does not satisfy the formula A1:Cs / Os≧2.0. According to the invention related to (((2))), cellulose particles are provided which are superior in hydrophobicity and dispersibility compared to those in which the relationship between the carbon atom amount Cs and the oxygen atom amount Os does not satisfy the formula A2: Cs / Os≧4.0. According to the invention related to (((3))), cellulose particles are provided which are superior in hydrophobicity and dispersibility compared to the case where the coating layer contains stearyl stearate. According to the invention related to (((4))), cellulose particles having excellent hydrophobicity and dispersibility are provided, as compared with the case where the amount of the coating layer relative to the base particles is less than 2 mass % or more than 30 mass %. According to the invention related to (((5))), cellulose particles are provided which are superior in hydrophobicity and dispersibility compared to cases in which the amount of the coating layer applied to the base particles is less than 4 mass % or exceeds 15 mass %. According to the invention related to (((6))), cellulose particles are provided which are superior in hydrophobicity and dispersibility compared to the case where no intermediate layer is provided between the base particles and the coating layer. According to the invention (((7))), cellulose particles are provided which are superior in hydrophobicity and dispersibility compared to when the intermediate layer contains carbomer. According to the invention related to (((8))), there is provided a cosmetic product which is excellent in sweat resistance and smearing resistance compared to the case where cellulose particles are used which have a circularity of less than 0.97 and in which the relationship between the amount of carbon atoms Cs and the amount of oxygen atoms Os, as measured by X-ray photoelectron spectroscopy, does not satisfy the formula A1:Cs / Os≧2.0, in which the cellulose particles have a base particle mainly composed of cellulose and a coating layer which coats the base particle.

Claims

1. A base particle mainly composed of cellulose; a coating layer that coats the base particles; having The average circularity is 0.97 or more, Cellulose particles, in which the relationship between the carbon atom amount Cs and the oxygen atom amount Os, as measured by X-ray photoelectron spectroscopy, satisfies the formula A1: Cs / Os≧2.

0.

2. 2. The cellulose particles according to claim 1, wherein the relationship between the carbon atom amount Cs and the oxygen atom amount Os satisfies formula A2: Cs / Os≧4.

0.

3. 2. The cellulose particles according to claim 1, wherein the coating layer comprises at least one coating material selected from the group consisting of fatty acids, fatty acid metal salts, amino acids, and amino acid salts.

4. 2. The cellulose granule according to claim 1, wherein the amount of the coating layer relative to the base particle is 2% by mass or more and 30% by mass or less.

5. The cellulose granules according to claim 4 , wherein the amount of the coating layer relative to the base particles is 4% by mass or more and 15% by mass or less.

6. The cellulose particles according to claim 1 , further comprising an intermediate layer between the base particle and the coating layer.

7. 7. The cellulose particle according to claim 6, wherein the intermediate layer contains at least one intermediate material selected from the group consisting of a polyamine compound, a polyquaternium, a polysaccharide compound, and a polyacrylic acid.

8. A cosmetic comprising the cellulose particles according to any one of claims 1 to 7.

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