JP7802909B2 - Crosslinked polymer particles for cosmetics or quasi-drugs - Google Patents

Description

The present invention relates to crosslinked polymer particles for use in cosmetics or quasi-drugs.

Various thickeners are used in cosmetics and quasi-drugs to improve the feel when applied to the skin. Specifically, thickening agents such as carboxyvinyl polymer, xanthan gum, cellulose, guar gum, and polyacrylic acid are used. By using these agents for different purposes and varying the amounts and ingredients, it is possible to create cosmetics with a viscosity ranging from low to thick, like a lotion, to solid gels like hair tics.

Among these thickeners, carboxyvinyl polymer is widely used because it is inexpensive, has a high thickening effect, and gels in small amounts. However, carboxyvinyl polymer has problems such as being sticky when applied to the skin when the amount added is increased to achieve a thickening effect.

To address these issues, for example, Patent Document 1 describes a viscous composition containing an alkyl-modified carboxyl group-containing water-soluble polymer and a polyalkylene oxide modification, which exhibits high thickening properties even when incorporated in small amounts. Furthermore, Patent Document 2 describes a cosmetic containing a water-absorbent resin obtained by reverse-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a petroleum-based hydrocarbon dispersion medium in the presence of a surfactant and a water-soluble radical polymerization initiator, and describes the provision of a cosmetic with excellent spreadability and feel upon application.

Japanese Patent Publication No. 2016-74758 Japanese Patent Publication No. 2012-241000

While cosmetics or quasi-drugs that use thickeners have been developed to achieve both thickening effects and reduced stickiness on the skin, it has been discovered that cosmetics that use the polymers described in Patent Documents 1 and 2 have the problem that increasing the amount added to improve the thickening effect reduces the feel of the product when applied to the skin.

The inventors conducted research in light of the above-mentioned problems and discovered that crosslinked polymer particles for cosmetics or quasi-drugs, which have a content of structural units derived from (meth)acrylic acid (salt) of 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of crosslinked polymer, and which have a volume average particle diameter of 8 μm or more and 20 μm or less, and a half-value width of 3 μm or more and less than 20 μm, can achieve both a thickening effect and a pleasant feel when applied to the skin, thereby completing the present invention.

The present invention provides crosslinked polymer particles for cosmetics or quasi-drugs that can achieve both a thickening effect and a pleasant feel when applied to the skin.

FIG. 1 is a graph showing the results of UV resistance evaluation of crosslinked polymer particles. FIG. 1 is a graph showing the results of evaluating the UV resistance of crosslinked polymer particles when a chelating agent is added. FIG. 1 is a graph showing the results of stability evaluation of crosslinked polymer particles under fluorescent light. FIG. 1 is a graph showing the results of stability evaluation of crosslinked polymer particles under fluorescent light when a chelating agent is added.

The crosslinked polymer particles according to one embodiment of the present disclosure are crosslinked polymer particles for use in cosmetics or quasi-drugs, having a structural unit derived from (meth)acrylic acid (salt) of 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the crosslinked polymer, a volume average particle diameter of 8 μm or more and 20 μm or less, and a half-value width of 3 μm or more and less than 20 μm.

In this disclosure, unless otherwise specified, the numerical range "A to B" means "greater than or equal to A and less than or equal to B."

In this disclosure, "acid (salt)" means "acid and/or its salt," and "(meth)acrylic" means "acrylic and/or methacrylic." In other words, "(meth)acrylic acid (salt)" means "acrylic acid (salt) and/or methacrylic acid (salt)."

In this disclosure, the term "resin" refers to a broader concept than polymer. A resin may contain one or more polymers, and may also contain materials other than polymers, such as additives, as needed.

In this disclosure, the term "crosslinked polymer particles" refers to particles primarily composed of a crosslinked polymer. Crosslinked polymer particles may be composed of one or more types of crosslinked polymers. Furthermore, crosslinked polymer particles may contain, if necessary, materials other than the crosslinked polymer, such as additives.

The structural unit derived from (meth)acrylic acid (salt) in one embodiment of the present disclosure may be formed by polymerizing (meth)acrylic acid (salt), or the structure may be formed by post-modification.

Examples of the (meth)acrylic acid (salt) according to one embodiment of the present disclosure include acrylic acid (salt) and methacrylic acid (salt), with acrylic acid (salt) being more preferred.

The (meth)acrylic acid according to one embodiment of the present disclosure is not particularly limited, and known (meth)acrylic acid may be used. This known (meth)acrylic acid can be obtained, for example, by capturing gaseous (meth)acrylic acid obtained by catalytic vapor-phase oxidation with a solvent such as water, and then purifying the resulting product by distillation, crystallization, or the like. The (meth)acrylic acid may contain trace amounts of components such as polymerization inhibitors and impurities.

The content ratio of structural units derived from (meth)acrylic acid (salt) per 100 parts by mass of the crosslinked polymer according to one embodiment of the present disclosure is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, and may be 70 parts by mass or more, or 90 parts by mass or more, with 100 parts by mass being particularly preferred.

The (meth)acrylic acid salt of the present disclosure is obtained by neutralizing the above-mentioned (meth)acrylic acid with the following basic compound.

(Basic Compound)
In one embodiment of the present disclosure, specific examples of the "basic compound" include alkali metal carbonates, alkali metal bicarbonates, alkali metal hydroxides, ammonia, organic amines, etc. Among these, from the viewpoint of the physical properties of the resulting crosslinked polymer particles, preferably, a compound exhibiting strong basicity is selected as the basic compound. That is, more preferably, a hydroxide of an alkali metal such as sodium, potassium, or lithium is used as the basic compound, and even more preferably, sodium hydroxide is used.

(neutralization)
In one embodiment of the present disclosure, the neutralization rate of (meth)acrylic acid is appropriately set within the range of preferably 10 mol% to 90 mol%, more preferably 40 mol% to 85 mol%, even more preferably 50 mol% to 80 mol%, and particularly preferably 60 mol% to 75 mol%, based on the acid groups of the monomer. If the neutralization rate is less than 10 mol%, the thickening property may decrease. On the other hand, if the neutralization rate exceeds 90 mol%, the pH of the crosslinked polymer particles may become excessively high. Note that when a monomer having an acid group other than (meth)acrylic acid is used, the neutralization rate is applied as the average neutralization rate of all monomers containing an acid group, including (meth)acrylic acid.
The crosslinked polymer particles of the present disclosure may be crosslinked polymer particles having 20 parts by mass or more of structural units derived from (meth)acrylic acid (salt) per 100 parts by mass of the crosslinked polymer, and may also contain structural units derived from a monomer other than (meth)acrylic acid (salt). When a monomer other than (meth)acrylic acid (salt) is used, a water-soluble monofunctional unsaturated monomer other than (meth)acrylic acid (salt) is preferred, and for example, a monofunctional unsaturated monomer having a carboxyl group other than (meth)acrylic acid (salt) can be suitably used.

A monofunctional unsaturated monomer specifically means a compound having one ethylenically unsaturated group per molecule.

The crosslinked polymer according to one embodiment of the present disclosure may contain structural units derived from monomers other than (meth)acrylic acid (salt). Examples of monomers other than (meth)acrylic acid (salts) include anionic unsaturated monomers and salts thereof, such as maleic acid (anhydride), itaconic acid, cinnamic acid, vinyl sulfonic acid, allyl toluene sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, 2-(meth)acryloylpropanesulfonic acid, and 2-hydroxyethyl (meth)acryloyl phosphate; mercaptan group-containing unsaturated monomers; phenolic hydroxyl group-containing unsaturated monomers; amide group-containing unsaturated monomers such as (meth)acrylamide, N-ethyl(meth)acrylamide, and N,N-dimethyl(meth)acrylamide; and amino group-containing unsaturated monomers such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylamide. Among these, (meth)acrylamide is preferably used. In one embodiment of the present disclosure, the content of the structural unit derived from (meth)acrylamide per 100 parts by mass of the crosslinked polymer is preferably 50 parts by mass or more and 80 parts by mass or less.

The crosslinked polymer particles according to one embodiment of the present disclosure are crosslinked polymer particles having 20 to 100 parts by mass of structural units derived from (meth)acrylic acid (salt) per 100 parts by mass of the crosslinked polymer, and preferably have a content of structural units derived from (meth)acrylic acid (salt) of 50 to 100 parts by mass per 100 parts by mass of the crosslinked polymer particles, and/or a content of structural units derived from (meth)acrylamide of 50 to 80 parts by mass per 100 parts by mass of the crosslinked polymer.

The crosslinked polymer according to an embodiment of the present disclosure may be crosslinked using a crosslinking agent. Furthermore, the crosslinked polymer particles according to an embodiment of the present disclosure may have a crosslinked structure at least inside the crosslinked polymer that constitutes the crosslinked polymer particle, and may also have a crosslinked structure on the surface of the crosslinked polymer that constitutes the crosslinked polymer particle, in other words, on the particle surface of the crosslinked polymer particle. From the viewpoint of water retention, it is preferable that the crosslinked polymer particles according to an embodiment of the present disclosure have a crosslinked structure on the particle surface.

As a crosslinking agent according to one embodiment of the present disclosure, an internal crosslinking agent that crosslinks the interior of the resulting crosslinked polymer particles, or a surface crosslinking agent that crosslinks the surface of the crosslinked polymer particles, can be used depending on the purpose. When a crosslinking agent is used, either the interior or the particle surface may be crosslinked, or both the interior and the particle surface may be crosslinked.

Specific examples of crosslinking agents that can be used as internal crosslinking agents in accordance with one embodiment of the present disclosure include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, N,N'-methylenebis(meth)acrylamide, triallyl isocyanurate, trimethylolpropane di(meth)allyl ether, triallylamine, tetraallyloxyethane, and glycerolpropoxytriacrylate. Compounds having two or more ethylenically unsaturated groups in one molecule; polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl alcohol, diethanolamine, tridiethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, sorbitol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,5-hexanediol, trimethylolpropane, sorbit, sorbitan, glucose, mannite, mannitan, sucrose, and glucose. polyglycidyl ethers such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and glycerin triglycidyl ether; polyvalent amine compounds such as diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, and triethylenetetramine; polyvalent glycidyl compounds such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether; 2,4-tolylene diisocyanate, ethylene carbonate (1,3-dioxolan-2-one), and propylene carbonate (4-methyl-1,3-dioxolan-2-one). polyhydric aziridine compounds such as 4,5-dimethyl-1,3-dioxolan-2-one, (poly, di, or mono)2-oxazolidinone, epichlorohydrin, epibromohydrin, diglycol silicate, and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate]; haloepoxy compounds such as epichlorohydrin and α-methylchlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; polyamines such as ethylenediamine; hydroxides, halides, carbonates, oxides, and borates such as borax of metals in Groups 2A, 3B, and 8 of the Periodic Table such as calcium hydroxide, calcium chloride, calcium carbonate, calcium oxide, borax magnesium chloride, magnesium oxide, aluminum chloride, zinc chloride, and nickel chloride; and polyvalent metal compounds such as aluminum isopropylate. As the internal crosslinking agent, a compound having two or more ethylenically unsaturated groups in one molecule is more preferred, and a compound having two or more ethylenically unsaturated groups in one molecule such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, etc. is even more preferred. In other words, the crosslinked polymer is preferably crosslinked with a compound having two or more ethylenically unsaturated groups in one molecule.

The amount of the internal crosslinking agent used is preferably set appropriately within the range of 0.0001% to 10% by mass, more preferably 0.001% to 1% by mass, and even more preferably 0.01% to 1% by mass, based on the total amount of monomer. By using an amount of the internal crosslinking agent within this range, a crosslinked polymer with the desired thickening properties can be obtained. Conversely, using an amount outside this range is not preferred, as it results in a decrease in gel strength, an increase in water-soluble content, a decrease in thickening properties, and a decrease in handleability after absorption.

The crosslinking agent that can be used as the surface crosslinking agent according to one embodiment of the present disclosure is not particularly limited, and examples include organic and inorganic surface crosslinking agents. Among these, organic surface crosslinking agents that react with carboxyl groups are preferred from the viewpoints of the physical properties of the resulting crosslinked polymer and the ease of handling of the surface crosslinking agent. Specific examples include polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 2,5-hexanediol, and trimethylolpropane; polyhydric amine compounds such as diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, and triethylenetetramine; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and glycerol. Examples of the surface cross-linking agent include polyvalent glycidyl compounds such as polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether; and polyvalent aziridine compounds such as 2,4-tolylene diisocyanate, ethylene carbonate (1,3-dioxolan-2-one), propylene carbonate (4-methyl-1,3-dioxolan-2-one), 4,5-dimethyl-1,3-dioxolan-2-one, (poly, di, or mono)2-oxazolidinone, epichlorohydrin, epibromohydrin, diglycol silicate, and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate], but are not limited to these compounds. Furthermore, these surface cross-linking agents may be used alone or in combination of two or more.

One or more surface cross-linking agents are selected from these, taking into consideration reactivity, etc.

In addition, from the viewpoint of ease of handling of the surface cross-linking agent and the absorption performance of the cross-linked polymer, a compound having two or more functional groups that react with a carboxyl group and that forms a covalent bond upon reaction with the carboxyl group is preferably selected. Specific examples of such organic compounds include polyhydric alcohol compounds, epoxy compounds, polyamine compounds, condensates of polyamine compounds and haloepoxy compounds, oxazoline compounds, oxazolidinone compounds, alkylene carbonate compounds, polyglycidyl compounds, oxetane compounds, vinyl ether compounds, and cyclic urea compounds.

The amount of the surface cross-linking agent used (the total amount when multiple agents are used) is appropriately set within the range of preferably 0.001 to 10 parts by mass, and more preferably 0.01 to 5 parts by mass, per 100 parts by mass of the cross-linked polymer. By keeping the amount of the surface cross-linking agent used within this range, an optimal cross-linked structure can be formed in the surface layer of the cross-linked polymer, resulting in cross-linked polymer particles that are easy to handle.

The crosslinked polymer particles according to one embodiment of the present disclosure may contain additives for various purposes. For example, to improve powder handling and the feel of the gel, they may contain organic or inorganic water-insoluble fine particles, water-soluble polymers, surfactants, polyhydric alcohols, or water-soluble polyvalent metal salts. They may also contain chelating agents, reducing agents, antioxidants, or hydroxycarboxylic acids (salts) to prevent deterioration or discoloration of the gel. They may also contain UV absorbers, dyes, pigments, or fragrances. The content of additives in the crosslinked polymer particles according to one embodiment of the present disclosure (the total content when multiple types are used) is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

From the viewpoint of the feel when the crosslinked polymer particle formulation is applied to the skin, the volume average particle diameter D10 of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 6 μm or more, and preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. Furthermore, from the above viewpoints, the volume average particle diameter D10 of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 1 μm to 20 μm, more preferably 3 μm to 15 μm, and even more preferably 6 μm to 10 μm.

From the viewpoint of the feel when the crosslinked polymer particle formulation is applied to the skin, the volume average particle diameter D50 of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 8 μm or more, more preferably 9 μm or more, even more preferably 10 μm or more, and preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 15 μm or less. Furthermore, from the above viewpoints, the volume average particle diameter D50 of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 8 μm to 20 μm, more preferably 9 μm to 18 μm, and even more preferably 10 μm to 15 μm.

From the viewpoint of the feel when the crosslinked polymer particle formulation is applied to the skin, the volume average particle diameter D90 of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 9 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 25 μm or less. Furthermore, from the above viewpoints, the volume average particle diameter D90 of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 9 μm to 50 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 25 μm.

In this disclosure, the volume average particle diameter "D10" means the particle diameter at which the cumulative frequency of the volume average particle diameter is 10% by volume, the volume average particle diameter "D50" means the particle diameter at which the cumulative frequency of the volume average particle diameter is 50% by volume, and the volume average particle diameter "D90" means the particle diameter at which the cumulative frequency of the volume average particle diameter is 90% by volume.

The volume average particle size of the crosslinked polymer particles in this disclosure can be measured using known methods, and can also be measured by the following method, for example. Measurement is performed using a HORIBA LA-950 laser diffraction scattering particle size distribution analyzer. Ethyl acetate is used as the circulating solvent during measurement, with the refractive index of the dispersion being 1.59 and the refractive index of the dispersion medium being 1.371. The median diameter (μm) is calculated from the volume-based particle size distribution obtained by measurement, and this is used as the volume average particle size.

The half-value width of the volume average particle diameter of the crosslinked polymer particles in one embodiment of the present disclosure is preferably 3 μm to 20 μm, more preferably 5 μm to 19 μm, even more preferably 7 μm to 18 μm, and particularly preferably 8 μm to 16 μm, from the viewpoint of the feel when the crosslinked polymer particle formulation is applied to the skin.

By having the half-value width of the volume average particle diameter of the crosslinked polymer according to one embodiment of the present disclosure within the above range, a good usability can be expected, with no slimy feeling when applied to the skin or stickiness when drying.

Furthermore, when the half-value width of the volume average particle diameter of the crosslinked polymer according to one embodiment of the present disclosure exceeds the above upper limit range, there is a concern that the feel of use may deteriorate, such as poor compatibility with the skin or increased squeaking sensation.

The half-value width of the volume average particle diameter of the crosslinked polymer particles disclosed herein can be measured using known techniques. For example, the half-value width can be calculated based on a particle size distribution graph obtained by measuring the volume average particle diameter. Specifically, the half-value of the frequency is calculated from the maximum frequency value, and the volume average particle diameter at half-value is calculated from the approximation curve between two points including the half-value. The difference between the calculated volume average particle diameters at the two points can then be taken as the half-value width.

From the viewpoint of the transparency of the crosslinked polymer particle blend, the turbidity of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 50% or less, more preferably 25% or less, and even more preferably 10% or less. The lower limit of the turbidity of the crosslinked polymer particles according to one embodiment of the present disclosure is not particularly limited and may be, for example, 0.01% or more, 0.1% or more, or 1% or more, but is preferably 0%.

The turbidity of the crosslinked polymer particles disclosed herein can be measured using known techniques, for example, by the following method.

The turbidity of crosslinked polymer particles can be measured using a Nippon Denshoku NDH7000 haze meter. A 1% by weight dispersion of crosslinked polymer particles is prepared as the measurement solution by rotating a HEIDON Three-One motor at 600 rpm for 30 minutes. The solution is then filled into a quartz cell with an optical path length of 10 mm, and the turbidity is measured at 25°C.

The crosslinked polymer particles according to one embodiment of the present disclosure may be crosslinked polymer particles that are water-swellable. The crosslinked polymer particles being water-swellable means that the water absorption capacity under no load (sometimes referred to as "water absorption capacity in physiological saline") for the following physiological saline solution (0.9% by mass sodium chloride aqueous solution) is 5 g/g or more.

The water absorption capacity without load of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 10 (g/g) or more, more preferably 20 (g/g) or more, and even more preferably 30 (g/g) or more. A saline water absorption capacity of 10 (g/g) or more allows for sufficient absorption of liquid to form a soft gel. Furthermore, the saline water absorption capacity of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 100 (g/g) or less, more preferably 60 (g/g) or less. A saline water absorption capacity of the crosslinked polymer particles of 100 (g/g) or less prevents excessive stickiness. Because the crosslinked polymer particles according to one embodiment of the present disclosure can absorb sufficient liquid and prevent excessive stickiness, the water absorption capacity without load of the crosslinked polymer particles according to one embodiment of the present disclosure is preferably 10 (g/g) to 100 (g/g), more preferably 20 (g/g) to 60 (g/g), and even more preferably 30 (g/g) to 60 (g/g).

In this disclosure, the method for measuring the saline water absorption capacity of crosslinked polymer particles is as follows. Unless otherwise specified, measurements of various performance characteristics of crosslinked polymer particles in this disclosure were performed indoors at a temperature of 25°C and a relative humidity of 40-50%, using an AC 100V, 60Hz power source.

As a pretreatment for measurement, the crosslinked polymer particles are dried at 80°C for 3 hours in a vacuum dryer with the pressure reduced to 5 kPa.

5 g of cross-linked polymer particles and 5 g of hydrophilic silica (Tokuyama; Reolosil-QS20) were placed in a 225 ml mayonnaise bottle and mixed by shaking for 30 minutes using a paint shaker (Toyo Seiki Seisakusho Co., Ltd., AC 100 V, single-phase 60 Hz, reference standard JIS K 5101-1-2:2004) to obtain a mixed sample for measurement (approximately 10 g).

A glass filter (120 mm diameter, JIS No. 0 pore size, 5 mm height) is placed in the center of a tray (SUS, square, D20 cm x L20 cm x H10 mm) and 200 g of 0.9% by weight sodium chloride aqueous solution is added. Filter paper (ADVANTEC No. 2, 110 mm) is placed on top of the glass filter, and then a 6 cm diameter cylindrical cylinder (Machintek C-207431-D-2 with screen (400 mesh)) with a 400 mesh stainless steel mesh attached to one opening is placed on top.

The measurement mixture sample (WS 0.2 g) is evenly dispersed in the cylinder over 20 seconds. After dispersing, the cylinder is left to stand for 30 minutes, and then the total mass of the cylinder (WS1) containing the post-measurement sample is measured. Additionally, as a blank measurement, a sample containing only hydrophilic silica (WBS 0.1 g) is measured.

Using the above measurement results, calculate the saline water absorption capacity (g/g) of the crosslinked polymer particles using the following formula.

Water absorption capacity of the crosslinked polymer particles in physiological saline solution (g/g) = (WS2 - WSS × FGAB) ÷ WSA
The definitions of the variables in the above formula are as follows:

WBC: Cylinder mass (g)
WBS: Mass of silica used in blank test (g)
WBS1: Total mass (g) of the cylinder after immersion for 30 minutes in the blank test
WBS2: Water absorption amount in blank test (g) = WBS1 - (WBC + WBS)
FGAB: Silica water absorption capacity (g/g) obtained from blank test = WBS2/WBS
WSS1: mass of silica (g) used to prepare the mixed sample for measurement
WSA1: Mass (g) of crosslinked polymer particles used to prepare the mixed sample for measurement
RSS1: silica mass ratio in the measurement mixed sample (-) = WSS1 ÷ (WSS1 + WSA1)
RSA1: mass ratio of crosslinked polymer particles in the measurement mixed sample (-) = WSA1 ÷ (WSS1 + WSA1)
WS: mass (g) of the mixed sample used in the measurement
WSS: mass of silica in the measurement mixed sample used for measurement (g) = WS × RSS1 WSA: mass of crosslinked polymer particles in the measurement mixed sample used for measurement (g) = WS × RSA1
WS1: Total mass of the cylinder after immersion for 30 minutes (g)
WS2: Water absorption amount (g) = WS1-(WBC+WS).

The crosslinked polymer particles according to one embodiment of the present disclosure preferably have a deionized water absorption capacity under no pressure (sometimes referred to as "deionized water absorption capacity") of 10 (g/g) or more, more preferably 20 (g/g) or more, and even more preferably 30 (g/g) or more. A deionized water absorption capacity of 10 (g/g) or more allows the particles to absorb a sufficient amount of liquid to form a soft gel. The upper limit of the deionized water absorption capacity of the crosslinked polymer particles according to one embodiment of the present disclosure is not particularly limited, but may be, for example, 150 (g/g) or less, 100 (g/g) or less, or 50 (g/g) or less.

As a method for measuring the deionized water absorption capacity of crosslinked polymer particles in the present disclosure, there can be mentioned a method for measuring the saline water absorption capacity described above, in which deionized water is used instead of a 0.9% by mass sodium chloride aqueous solution.

The ratio of the deionized water absorption capacity of the crosslinked polymer particles to the physiological saline water absorption capacity is preferably 1 to 10 times, more preferably 1 to 8 times, and even more preferably 1 to 5 times. By keeping the ratio of deionized water absorption capacity to physiological saline water absorption capacity within this range, the sensation of use is stable regardless of whether or not the particles come into contact with sweat containing salt.

The crosslinked polymer particles according to one embodiment of the present disclosure preferably have a soluble content of 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, per 100% by mass of the crosslinked polymer particles. Setting the soluble content to 50% by mass or less prevents excessive stickiness. The lower limit of the soluble content of the crosslinked polymer particles according to one embodiment of the present disclosure is not particularly limited, but may be, for example, 0.01% by mass or more, 0.1% by mass or more, or 1% by mass or more.

The method for measuring the soluble content of crosslinked polymer particles in this disclosure is as follows.

As a pretreatment for measurement, the crosslinked polymer particles are dried at 80°C for 3 hours in a vacuum dryer with the pressure reduced to 5 kPa.

500 g of 0.9% by weight NaCl aqueous solution was placed in a 500 mL beaker, and a stirrer (8 mm diameter x 30 mm, no ring) was placed in the beaker and adjusted to rotate at 600 rpm. 2.000 g of crosslinked polymer particles were placed in the beaker over 1 minute, stirred at 25 ° C for 3 hours, and then filtered using filter paper (ADVANTEC, No. 2). If the filtration was slow, the filtrate may be divided and filtered using multiple funnels. 80 g of the obtained filtrate was weighed into a 100 mL beaker previously weighed at 140 ° C., and dried for 16 hours in a hot air dryer (Espec Corporation, PHH102) at 140 ° C., and the mass of the filtrate solids, Wa (g), was measured. The above procedure was repeated without using the crosslinked polymer particles, and the mass of the filtrate solids, Wb (g), was measured. The soluble content was calculated using the following formula:
Soluble content of crosslinked polymer particles (mass %)=[((Wa−Wb)/80)×500/2]×100.

The viscosity of a formulation in which the crosslinked polymer particles according to one embodiment of the present disclosure are blended with purified water to a concentration of 1% by mass is preferably 5,000 mPa·s or more, more preferably 10,000 mPa·s or more, and even more preferably 20,000 mPa·s or more, from the viewpoint of thickening properties when used as a cosmetic or quasi-drug; and is preferably 50,000 mPa·s or less, more preferably 30,000 mPa·s or less, and even more preferably 25,000 mPa·s or less, from the viewpoint of usability. Furthermore, since suitable thickening properties and a good feel when used as a cosmetic or quasi-drug can be achieved at the same time, the viscosity of a blend obtained by blending the crosslinked polymer particles according to an embodiment of the present disclosure with purified water to give a concentration of 1% by mass is preferably 5,000 mPa·s to 50,000 mPa·s, more preferably 10,000 mPa·s to 30,000 mPa·s, and even more preferably 20,000 mPa·s to 25,000 mPa·s.

The viscosity of a compound containing the crosslinked polymer particles of the present disclosure can be measured using known methods, for example, using a Toki Sangyo Co., Ltd. B-type viscometer TVB-10 under conditions of rotor TM4, rotation speed of 6 rpm, measurement time of 60 seconds, and temperature of 25°C.

In addition, for high viscosity formulations that are difficult to measure under the above conditions, it is possible to measure them by changing the rotation speed to 1.5 rpm.

The crosslinked polymer particles according to an embodiment of the present disclosure preferably contain silicon dioxide, as this can improve the feel when used as a cosmetic. From the viewpoint of achieving an excellent feel when used as a cosmetic, the content of silicon dioxide per 100 parts by mass of the crosslinked polymer particles according to an embodiment of the present disclosure is preferably 0.5 parts by mass or less, more preferably 0.3 parts by mass or less, and even more preferably 0.1 parts by mass or less. When the crosslinked polymer particles according to an embodiment of the present disclosure contain silicon dioxide, the lower limit of the content of silicon dioxide per 100 parts by mass of the crosslinked polymer particles is not particularly limited, but may be, for example, 0.0001 parts by mass or more, 0.001 parts by mass or more, or 0.01 parts by mass or more.

<Method of producing crosslinked polymer particles>
Hereinafter, the method for producing crosslinked polymer particles of the present disclosure will be described in detail using an example, but the method for producing crosslinked polymer particles of the present disclosure is not limited thereto.

(i) Step of Preparing an Aqueous Monomer Solution This step is a step of preparing an aqueous solution of a monomer (hereinafter referred to as "aqueous monomer solution"). In addition to the monomer, an internal crosslinking agent and other substances described below may be added to the aqueous monomer solution, if necessary.

For convenience, this section describes an aqueous monomer solution, but a monomer slurry solution can also be used as long as the water absorption performance of the crosslinked polymer particles obtained as the final product is not reduced.

(monomer)
In one embodiment of the present disclosure, from the viewpoint of the physical properties and productivity of the crosslinked polymer, a monomer composition containing (meth)acrylic acid and/or a (meth)acrylic acid salt is used as a monomer. The (meth)acrylic acid and/or (meth)acrylic acid salt of the present disclosure is as described above. That is, the monomer composition according to one embodiment of the present disclosure is a composition containing 20 parts by mass or more and 100 parts by mass or less of (meth)acrylic acid (salt) per 100 parts by weight of the monomer composition.

The "(meth)acrylic acid" is not particularly limited, and known (meth)acrylic acids can be used. Such known (meth)acrylic acid can be obtained, for example, by capturing gaseous (meth)acrylic acid obtained by catalytic vapor-phase oxidation with a solvent such as water, and then purifying it by distillation, crystallization, or other methods. (Meth)acrylic acid may contain trace amounts of components such as polymerization inhibitors and impurities.

The "(meth)acrylic acid salt" used is the (meth)acrylic acid described above neutralized with the basic compound described below. However, the (meth)acrylic acid salt may be a commercially available (meth)acrylic acid salt (e.g., sodium (meth)acrylate) or may be one obtained by neutralizing (meth)acrylic acid in a crosslinked polymer manufacturing plant.

(Basic Compound)
In one embodiment of the present disclosure, specific examples of the "basic compound" include alkali metal carbonates, alkali metal bicarbonates, alkali metal hydroxides, ammonia, organic amines, and the like. Among these, from the viewpoint of the physical properties of the resulting crosslinked polymer, preferably, a compound exhibiting strong basicity is selected as the basic compound. That is, more preferably, a hydroxide of an alkali metal such as sodium, potassium, or lithium is used as the basic compound, and even more preferably, sodium hydroxide is used. Note that, from the viewpoint of handleability, the basic compound is preferably in the form of an aqueous solution.

(neutralization)
When using acrylic acid neutralized in a crosslinked polymer production plant as the acrylic acid salt, the timing of neutralization can be the following (1) to (3): (1) neutralization of acrylic acid (before polymerization), (2) neutralization during the crosslinking polymerization of acrylic acid (during polymerization), and (3) neutralization of a hydrogel-like crosslinked polymer obtained by crosslinking polymerization of acrylic acid (after polymerization). In one embodiment of the present disclosure, any of (1) to (3) can be selected or used in combination as the timing of neutralization. Furthermore, these neutralizations can be performed continuously or batchwise, and are not particularly limited; however, continuous neutralization is preferred from the viewpoint of crosslinked polymer production efficiency.

In one embodiment of the present disclosure, the neutralization rate of (meth)acrylic acid is as described above. The above-described range of neutralization rate applies to any of the neutralizations before, during, and after polymerization. The above-described neutralization rate also applies to various forms of crosslinked polymers in the crosslinked polymer manufacturing process, including the crosslinked polymer as a final product (e.g., hydrogel-like crosslinked polymer after polymerization, dried polymer after drying, crosslinked polymer particles before surface crosslinking, crosslinked polymer particles after surface crosslinking, etc.).

Regarding the neutralization device and neutralization conditions such as neutralization temperature and residence time, the conditions described in International Publication No. 2009/123197, etc., apply to one embodiment of the present disclosure.

(Other monomers)
In one embodiment of the present disclosure, a monomer other than the above-mentioned acrylic acid (salt) (hereinafter referred to as "other monomer") can be used in combination with acrylic acid (salt) as needed. In other words, the monomer composition may be a mixture of (meth)acrylic acid (salt) and other monomer. The compound and composition used as the other monomer are as described above.

(Internal crosslinking agent)
The compound and composition used as the internal crosslinking agent in the method for producing crosslinked polymer particles according to one embodiment of the present disclosure are as described above.

In one embodiment of the present disclosure, a method is preferably employed in which the internal cross-linking agent is added in advance when preparing the aqueous monomer solution, and the cross-linking reaction (cross-linking polymerization) is carried out simultaneously with the polymerization reaction. However, as long as the polymer interior can be cross-linked, this method is not limited to this. A method may also be employed in which polymerization is carried out without adding an internal cross-linking agent, and then an internal cross-linking agent is added during or after the polymerization to effect cross-linking. These methods may also be used in combination.

(Other substances added to the aqueous monomer solution)
In one embodiment of the present disclosure, from the viewpoint of improving the physical properties of the resulting crosslinked polymer particles, the following substances can be added at one or more of the following points: when preparing the monomer aqueous solution, during the polymerization process, and after the polymerization process. The substances are not particularly limited, but examples include hydrophilic polymers such as starch, starch derivatives, cellulose, cellulose derivatives, polyvinyl alcohol, polyacrylic acid (salts), and crosslinked polyacrylic acid (salts). Alternatively, the substances may be compounds such as carbonates, azo compounds, foaming agents such as bubbles, surfactants, and chain transfer agents. These substances may be added alone or in combination of two or more.

The amount of the hydrophilic polymer added is appropriately set within the range of preferably 50% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less (lower limit: 0%), based on the total amount of the monomers (including other monomers). Furthermore, the amount of the compound added is appropriately set within the range of preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less (lower limit: 0%), based on the total amount of the monomers (including other monomers).

When a water-soluble resin or cross-linked polymer is used as the hydrophilic polymer, a graft polymer or cross-linked polymer composition (e.g., starch-acrylic acid polymer, PVA-acrylic acid polymer, etc.) is obtained, and these polymers and cross-linked polymer compositions are also included in the category of cross-linked polymers in one embodiment of the present disclosure.

(Monomer component concentration)
In this step, the above-described components are appropriately selected depending on the purpose, and predetermined amounts of each component satisfying the above-described ranges are mixed to prepare an aqueous monomer solution. The monomer containing acrylic acid (salt) is preferably used as an aqueous solution or in a state dissolved in a mixed solvent of water and a hydrophilic solvent, more preferably as an aqueous solution. The concentration of the monomer component in the aqueous monomer solution is not particularly limited, but is appropriately set within a range of preferably 10% by mass to 80% by mass, more preferably 20% by mass to 75% by mass, and even more preferably 30% by mass to 70% by mass, from the viewpoint of the physical properties of the crosslinked polymer.
The "monomer component concentration" is a value calculated from the following formula 1, and in formula 1, the mass of the aqueous monomer solution does not include the mass of the graft component, the crosslinked polymer, or the hydrophobic organic solvent in the reversed-phase suspension polymerization.

Concentration of monomer component (mass%)=(mass of monomer component)/(mass of aqueous monomer solution)×100 (Equation 1)
(ii) Polymerization Step This step is a step of polymerizing the aqueous monomer solution obtained in the aqueous monomer solution preparation step to obtain a hydrogel-like crosslinked polymer (hereinafter, sometimes referred to as "hydrogel").

(Polymerization initiator)
The polymerization initiator used in this step may be a thermally decomposable polymerization initiator, a photodecomposable polymerization initiator, or a redox-based polymerization initiator used in combination with a reducing agent that promotes the decomposition of these polymerization initiators. For example, polymerization initiators described in U.S. Pat. No. 7,265,190 or the like may be used. One or more polymerization initiators are selected from these, taking into consideration factors such as the polymerization form. Furthermore, from the viewpoint of the ease of handling of the polymerization initiator and the physical properties of the crosslinked polymer, the polymerization initiator is preferably a peroxide or an azo compound, more preferably a peroxide, and even more preferably a persulfate.

The amount of the polymerization initiator used is preferably set within a range of 0.001 to 1 part by mass, and more preferably 0.001 to 0.5 parts by mass, relative to 100 parts by mass of the total amount of monomers (including other monomers). Furthermore, the amount of the reducing agent used is preferably set within a range of 0.0001 to 0.02 parts by mass, relative to the total amount of monomers (including other monomers). By keeping the amounts of the polymerization initiator and reducing agent used within these ranges, a crosslinked polymer with the desired performance can be obtained.

The polymerization reaction of one embodiment of the present disclosure may also be initiated by irradiation with active energy rays such as radiation, electron beams, or ultraviolet rays. Alternatively, irradiation with the active energy rays may be used in combination with the polymerization initiator.

(polymerization form)
The polymerization form of the aqueous monomer solution used in the polymerization step according to an embodiment of the present disclosure is not particularly limited, and examples include aqueous solution polymerization, reversed-phase suspension polymerization, spray polymerization, droplet polymerization, bulk polymerization, and precipitation polymerization. Among these, taking into consideration the controllability of polymerization and the water absorption performance of the crosslinked polymer, aqueous solution polymerization or reversed-phase suspension polymerization is preferably selected, more preferably aqueous solution polymerization, and even more preferably continuous aqueous solution polymerization. Specific examples of continuous aqueous solution polymerization include continuous belt polymerization, as described in U.S. Pat. No. 4,893,999, and continuous kneader polymerization, as described in U.S. Pat. No. 6,987,151. Crosslinked polymers can be produced with high productivity by these continuous aqueous solution polymerizations.

While each of the above polymerization methods can be carried out in an air atmosphere, they are preferably carried out in an inert gas atmosphere such as nitrogen or argon (e.g., an oxygen concentration of 1% by volume or less) to prevent discoloration of the resulting crosslinked polymer. Dissolved oxygen in the aqueous monomer solution is also preferably sufficiently replaced with an inert gas (e.g., the amount of dissolved oxygen is less than 1 mg/L).

The polymerization process according to one embodiment of the present disclosure can also be described as a process for polymerizing a monomer composition containing 20 parts by mass or more and 100 parts by mass or less of (meth)acrylic acid (salt) per 100 parts by mass of total monomers.

(iii) Gel Crushing Step This step is a step of crushing the hydrogel obtained in the polymerization step to obtain a particulate hydrogel (hereinafter referred to as "particulate hydrogel"). The "gel crushing" refers to crushing the hydrogel into particles using a gel crusher such as a kneader, meat chopper, or cutter mill. Regarding the embodiments and conditions of gel crushing, for example, the contents described in International Publication No. 2011/126079 and the like are applicable to one embodiment of the present disclosure.

When kneader polymerization is selected as the polymerization method, the polymerization process and gel crushing process are carried out simultaneously. Furthermore, when a particulate hydrogel is obtained during the polymerization process, such as in reverse-phase suspension polymerization or droplet polymerization, the gel crushing process may not be carried out.

Therefore, the hydrogel obtained in the polymerization step is subjected to the subsequent drying step either in the form of particles or in the form of particles obtained by gel pulverization. The mass average particle diameter (D50) of the particulate hydrogel (measured in accordance with paragraph [0255] (d) of WO 2011/126079, "Weight average particle diameter (D50) and logarithmic standard deviation (σζ) of particle size distribution") is appropriately set, from the viewpoint of drying efficiency, preferably within the range of 0.1 mm to 50 mm, more preferably 0.1 mm to 10 mm, and even more preferably 0.2 mm to 5 mm.

(iv) Drying Step This step is a step of drying the particulate hydrogel obtained in the polymerization step or the particulate hydrogel obtained in the gel crushing step to a desired solid content range to obtain a dried polymer. The desired solid content range is preferably 80% by mass or more, more preferably 85% to 99% by mass, even more preferably 90% to 98% by mass, and particularly preferably 92% to 97% by mass. Here, the "solid content" is a value calculated from the loss on drying (the change in mass when 1 g of sample is dried at 180 ° C. for 3 hours) and is calculated from the following (Equation 2).
Solid content (mass%) = (mass of sample (1 g) - loss on drying) / (mass of sample (1 g)) × 100 (Equation 2)
The drying method in one embodiment of the present disclosure is not particularly limited, and examples thereof include heat drying, hot air drying, reduced pressure drying, fluidized bed drying, infrared drying, microwave drying, drum dryer drying, drying by azeotropic dehydration with a hydrophobic organic solvent, high-humidity drying using high-temperature water vapor, etc. Among these, from the viewpoint of drying efficiency, hot air drying is preferably selected, and more preferably band drying in which hot air drying is performed on a ventilated belt is selected.

While the drying temperature in this process is not particularly limited, it is preferably set within the range of 120°C to 250°C, more preferably 150°C to 200°C, from the viewpoints of drying efficiency and the color tone of the crosslinked polymer. Furthermore, the drying time is preferably set within the range of 10 to 120 minutes, more preferably 20 to 90 minutes, and even more preferably 30 to 60 minutes. Setting the drying temperature and drying time within these ranges allows for the modification of the polymer chains within the crosslinked polymer and reduces damage, resulting in a high-physical property crosslinked polymer with a suppressed increase in soluble content. In other words, by setting the drying temperature and drying time within these ranges, the physiological saline water absorption capacity and soluble content of the crosslinked polymer can be adjusted to the desired range. The drying temperature is typically determined by the temperature of the heat medium (e.g., in the case of hot air drying, it is determined by the temperature of the hot air). However, in cases where the temperature cannot be determined by the temperature of the heat medium, such as microwave drying, it is determined by the temperature of the particulate hydrogel. The drying temperature may be constant or may be changed as appropriate during drying.

Drying conditions other than the drying temperature and drying time may be set appropriately depending on the moisture content of the particulate hydrogel, the amount of particulate hydrogel supplied to the drying process, the desired solid content, etc. When band drying is selected, the conditions described in, for example, International Publication No. 2006/100300, etc., are applicable to one embodiment of the present disclosure.

(v) Pulverization step, classification step In this step, the dried polymer obtained in the drying step is pulverized (pulverization step) and adjusted to a particle size within a desired range (classification step) to obtain crosslinked polymer particles having a desired particle size. Note that this pulverization step differs from the gel pulverization step (iii) in that the dried polymer to be pulverized has undergone a drying step. Note that in this specification, the crosslinked polymer particles that have undergone the drying step before surface crosslinking are sometimes referred to as "crosslinked polymer powder before surface crosslinking" or "crosslinked polymer powder A".

The mill used in this process may be either continuous or batch type. Specific examples include roll mills, vibration mills, ball mills, hammer mills, pin mills, flash mills, and jet mills. The term "ball mill" is not limited to ball mills, but rather encompasses rod mills and compound mills. Preferred mills are those that break the material suspended or falling in the air upon impact and prevent contact between mill components. Specific examples include pin mills, flash mills, and jet mills. These three preferred mill types offer the advantages of minimal temperature rise in the material during milling, thereby minimizing deterioration of the crosslinked polymer particles. Furthermore, the mill itself is virtually free of wear and damage, resulting in minimal contamination of the milled product. Jet mills include fluidized-bed jet mills, impactor-type jet mills, and rotary mechanical mills. Fluidized-bed jet mills, particularly airflow jet mills, are preferred. When an air jet mill is used, the grinding pressure is, for example, 0.01 MPa or more, preferably 0.05 MPa or more, more preferably 0.1 MPa or more, and for example, 3 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less.

Because the particle size of the crosslinked polymer particles according to one embodiment of the present disclosure is very fine, they are preferably pulverized in multiple stages. That is, they are first coarsely pulverized (first pulverization step), and then further finely pulverized (second and subsequent pulverization steps). Preferably, the multi-stage pulverization is performed using multiple types of pulverizers in combination. The combination of pulverizers varies depending on the particle size before pulverization and the target particle size, but the first-stage pulverizer is preferably a roll mill, vibration mill, hammer mill, or pin mill. Furthermore, to obtain a crosslinked polymer having the average particle size of the present invention, a jet mill or ball mill, more preferably a jet mill, is preferably used in the final pulverization step. Note that, in this specification, the final pulverization step may also be referred to as fine pulverization.

It is also preferred to use a flash mill between the first and final grinding steps.
From the viewpoint of pulverization efficiency, it is preferable to adjust the temperature of the pulverization chamber inner wall in each pulverization step, and the temperature is preferably 30 to 150° C., more preferably 35 to 120° C., and particularly preferably 40 to 100° C. By adjusting the temperature to the above range, adhesion of the crosslinked polymer particles is less likely to occur, and they can be easily discharged from the pulverizer.

The relative humidity inside the grinding chamber is preferably 70% RH or less, more preferably 50% RH or less, and even more preferably 30% RH or less. In grinders that supply gas to the grinding chamber, such as jet mills, the dew point of the gas is preferably 0°C or less, more preferably -5 to -80°C, and particularly preferably -10 to -50°C. Other operating conditions can be set appropriately taking into account the particle size and processing volume of the material to be ground, the size of the grinder, etc.

In addition, coarse particles can be removed by introducing a classification process. The equipment (classifier) used in the classification process is not particularly limited, but examples include a sieve classifier and an air classifier. Furthermore, a device with a grinding function, such as a Turbo Screener (manufactured by Matsubo Co., Ltd.), can also be used, in which case the grinding and classification processes are carried out simultaneously. The classification process can be carried out simultaneously with the grinding process, before the grinding process to remove coarse particles that are difficult to grind, and/or after the grinding process to remove particles larger than the desired particle size for the crosslinked polymer of the present disclosure. Furthermore, when grinding is performed in multiple stages, it can also be carried out between grinding processes. Large particles removed in the classification process are preferably ground again to reduce loss.

The irregularly pulverized crosslinked polymer particles obtained in this manner have the particle size described above. Furthermore, the particle size can be adjusted appropriately not only during this process (pulverization process and classification process) but also during the polymerization process (particularly in the case of reverse-phase suspension polymerization or droplet polymerization).

(vi) Surface Cross-Linking Step This step is carried out for the purpose of improving the water absorption rate and liquid dispersibility of the cross-linked polymer particles after drying and pulverization. This step further provides a high cross-link density portion on the surface layer of the cross-linked polymer particles after drying, and is composed of, for example, a mixing step and a heat treatment step. In this surface cross-linking step, radical cross-linking and/or monomer polymerization is carried out in the surface layer of the cross-linked polymer particles, or a cross-linking reaction between the surface layer of the cross-linked polymer particles and a surface cross-linking agent is carried out, thereby obtaining surface-cross-linked cross-linked polymer particles. This step is also carried out for the purpose of improving the handleability of the cross-linked polymer particles after drying during pulverization, and may be carried out on cross-linked polymer particles before pulverization to the particle size of the final product, for example, on pulverized intermediates. In this case, the surface cross-linked layer of this step may not remain on the surface of the cross-linked polymer particles of the final product.

(vi-1) Mixing Step This step is a step in which a surface cross-linking agent is mixed with the cross-linked polymer particles after drying and pulverization to obtain a moistened mixture.

(Surface cross-linking agent)
The compound and composition used as the surface cross-linking agent in one embodiment of the present disclosure are as described above.

The surface cross-linking agent is preferably added to the cross-linked polymer particles as an aqueous solution (surface cross-linking agent solution). In this case, the amount of the surface cross-linking agent solution used is appropriately set within the range of preferably 0.1 to 20 parts by mass, more preferably 0.3 to 15 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the cross-linked polymer particles. By keeping the amount of water used within this range, the handleability of the surface cross-linking agent solution is improved, and the surface cross-linking agent can be evenly mixed with the cross-linked polymer particles.

(vi-2) Heat Treatment Step This step is a step in which the humidified mixture obtained in the mixing step is heat treated to obtain surface-crosslinked crosslinked polymer particles.

(Heat treatment method)
The method for heating the humidified mixture is not particularly limited, and the humidified mixture may be heated in a stationary state or by using a mixing means such as stirring. From the viewpoint of ensuring uniform heating throughout the humidified mixture, heating under stirring and mixing is preferred. Preferred examples of the apparatus used in this step include a mortar mixer, a paddle dryer, a multi-fin processor, and a tower dryer.

The heating temperature in this process is not particularly limited and may be set depending on the type and amount of surface cross-linking agent used, the desired absorption performance of the cross-linked polymer particles, etc., but is preferably set appropriately within the range of 70°C to 250°C, more preferably 90°C to 210°C, as the heat medium temperature. The heating time is also not particularly limited, but is preferably set appropriately within the range of 1 minute to 2 hours.

(viii) Step of Adding Other Additives In one embodiment of the present disclosure, additives other than those described above can be added to the crosslinked polymer particles to impart various functions. Specific examples of other additives include polyvalent metal salt compounds, α-hydroxycarboxylic acid compounds, surfactants, compounds containing phosphorus atoms, oxidizing agents, organic reducing agents, water-insoluble inorganic fine particles, organic powders such as metal soaps, pulp and thermoplastic fibers, deodorants, antibacterial agents, disinfecting components, fragrances, foaming agents, pigments, dyes, plasticizers, adhesives, fertilizers, salts, cationic polymers, hydrophilic polymers such as polyethylene glycol and polyethyleneimine, hydrophobic molecules such as paraffin, thermoplastic resins such as polyethylene and polypropylene, and thermosetting resins such as polyester resins and urea resins. The surfactants preferably include compounds disclosed in International Publication No. 2005/075070.

The amount of additive used (added amount) is determined appropriately depending on the application and is not particularly limited, but is preferably 3 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of crosslinked polymer particles. Alternatively, the additive can be added to the crosslinked polymer particles in a separate step (other additive addition step) separate from the above step.

(ix) Other Steps In one embodiment of the present disclosure, in addition to the steps described above, a humidifying step, a granulating step, a sizing step, a fine powder removal step, a fine powder recycling step, etc. may be provided as needed. Furthermore, one or more steps such as a transporting step, a storage step, a packaging step, and a preservation step may be further included. The "sizing step" includes a fine powder removal step subsequent to the surface crosslinking step, and a step of classifying and pulverizing the crosslinked polymer when it aggregates and exceeds the desired size. The humidifying step is a step of adding water to the crosslinked polymer particles to increase the water content, which may improve handleability. The added water may be liquid water or water vapor, or may be an aqueous solution or a fine particle dispersion.

<Application>
The crosslinked polymer particles according to an embodiment of the present disclosure are expected to provide an excellent feel when used as a cosmetic or quasi-drug. That is, in one embodiment of the present disclosure, a cosmetic or quasi-drug (sometimes simply referred to as a "cosmetic or quasi-drug") using the crosslinked polymer particles according to an embodiment of the present disclosure is provided. A cosmetic or quasi-drug using the crosslinked polymer particles can also be said to be a cosmetic or quasi-drug containing the crosslinked polymer particles.

In one embodiment of the present disclosure, the cosmetic or quasi-drug is preferably used as a skin cosmetic or quasi-drug.

Skin cosmetics and quasi-drugs for the skin may be in any form, such as liquid, gel, cream, semi-solid, solid, stick, or powder, and can be skin cosmetics and quasi-drugs such as emulsions, creams, lotions, serums, packs, facial cleansers, and makeup cosmetics.

Cosmetics according to one embodiment of the present disclosure include skin cosmetics, topical skin preparations, hair cosmetics, topical hair preparations, etc.

The content of the crosslinked polymer particles in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more, from the viewpoint of obtaining a thickening effect. The upper limit of the content of the crosslinked polymer particles in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is not particularly limited, but may be, for example, 20.0 parts by mass or less, 10.0 parts by mass or less, or 5.0 parts by mass or less.

A cosmetic or quasi-drug according to an embodiment of the present disclosure may contain compounds other than the crosslinked polymer particles according to an embodiment of the present disclosure. Examples of compounds other than the crosslinked polymer particles include thickeners, powder components, pH adjusters, nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, oils, moisturizers, water-soluble polymers, antioxidants, UV absorbers, chelating agents, preservatives, antibacterial agents, colorants, and fragrances.

Examples of thickeners in accordance with one embodiment of the present disclosure include dextrin, sodium pectinate, sodium alginate, PVM (methyl vinyl ether), locust bean gum, tamarind gum, dialkyldimethylammonium cellulose sulfate, aluminum magnesium silicate, bentonite, hectorite, AlMg silicate (beegum), laponite, and silicic anhydride.

The content of the thickener contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.05 parts by mass or more, and preferably 3 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less. The content of the thickener contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 to 3 parts by mass, more preferably 0.005 to 1 part by mass, and even more preferably 0.05 to 0.5 parts by mass.

Examples of powder components according to an embodiment of the present disclosure include inorganic powders (e.g., talc, kaolin, mica, sericite, muscovite, phlogopite, synthetic mica, lepidolite, biotite, vermiculite, magnesium carbonate, calcium carbonate, aluminum silicate, barium silicate, calcium silicate, magnesium silicate, strontium silicate, metal tungstate, magnesium, silica, zeolite, barium sulfate, calcined calcium sulfate (calcined gypsum), calcium phosphate, fluorapatite, hydroxyapatite, ceramic powder, and metal soaps (e.g., zinc myristate, calcium palmitate, aluminum stearate), boron nitride, etc.); organic powders (for example, polyamide resin powder (nylon powder), polyethylene powder, polymethyl methacrylate powder, polystyrene powder, styrene-acrylic acid copolymer resin powder, benzoguanamine resin powder, polytetrafluoroethylene powder, cellulose powder, etc.); inorganic white pigments (for example, titanium dioxide, zinc oxide, etc.); inorganic red pigments (for example, iron oxide (red iron oxide), iron titanate, etc.); inorganic brown pigments (for example, γ-iron oxide, etc.); inorganic yellow pigments (for example, yellow iron oxide, yellow ochre, etc.) etc.); inorganic black pigments (e.g., black iron oxide, low-order titanium oxide, etc.); inorganic purple pigments (e.g., mango violet, cobalt violet, etc.); inorganic green pigments (e.g., chromium oxide, chromium hydroxide, cobalt titanate, etc.); inorganic blue pigments (e.g., ultramarine, Prussian blue, etc.); pearl pigments (e.g., titanium oxide-coated mica, titanium oxide-coated bismuth oxychloride, titanium oxide-coated talc, colored titanium oxide-coated mica, bismuth oxychloride, fish scale foil, etc.); metal powder pigments (e.g., aluminum powder, copper powder, etc.); zirconium, Examples of organic pigments include barium or aluminum lakes (e.g., organic pigments such as Red No. 201, Red No. 202, Red No. 204, Red No. 205, Red No. 220, Red No. 226, Red No. 228, Red No. 405, Orange No. 203, Orange No. 204, Yellow No. 205, Yellow No. 401, and Blue No. 404, as well as Red No. 3, Red No. 104, Red No. 106, Red No. 227, Red No. 230, Red No. 401, Red No. 505, Orange No. 205, Yellow No. 4, Yellow No. 5, Yellow No. 202, Yellow No. 203, Green No. 3, and Blue No. 1); natural pigments (e.g., chlorophyll, β-carotene, etc.); and the like.

Examples of pH adjusters in accordance with one embodiment of the present disclosure include mixtures of hydroxycarboxylic acids and their alkali metal salts, such as lactic acid-sodium lactate and citric acid-sodium citrate; mixtures of dicarboxylic acids and their alkali metal salts, such as succinic acid-sodium succinate; alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, ammonia (which may be aqueous ammonia), citric acid, tartaric acid, lactic acid, phosphoric acid, neutral amino acids (e.g., threonine, cysteine, etc.), sodium acyl sarcosine (sodium lauroyl sarcosine), acyl glutamate, sodium acyl-β-alanine, glutathione, and pyrrolidone carboxylic acid.

A cosmetic or quasi-drug containing the crosslinked polymer particles according to one embodiment of the present disclosure has excellent dispersibility of inorganic white pigments, and preferably also excellent dispersibility of titanium dioxide. Since this allows for the provision of formulations (particularly sun care formulations) that are highly stable and have an excellent feel when used, it is preferable that the cosmetic or quasi-drug containing the crosslinked polymer particles according to one embodiment of the present disclosure contain an inorganic white pigment.

The mass ratio of the crosslinked polymer particles to the inorganic white pigment (mass of crosslinked polymer particles/mass of inorganic white pigment) in a cosmetic or quasi-drug according to one embodiment of the present disclosure may be 1/3 to 1/30, 1/5 to 1/20, or 1/8 to 1/15. Here, the mass of the crosslinked polymer particles refers to the mass of dried crosslinked polymer particles. Specifically, the dried crosslinked polymer particles can be obtained by drying the crosslinked polymer particles in a hot air dryer at a temperature of 150°C to 200°C for a certain period of time (e.g., approximately 30 to 90 minutes), as described in the Examples.

The content of the pH adjuster contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, and preferably 3 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less. The content of the pH adjuster contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 to 3 parts by mass, more preferably 0.005 to 1 part by mass, and even more preferably 0.01 to 0.5 parts by mass.

Nonionic surfactants according to one embodiment of the present disclosure include POE sorbitan fatty acid esters (e.g., POE sorbitan monooleate, POE sorbitan monostearate, POE sorbitan monooleate, POE sorbitan tetraoleate, etc.); POE sorbitol fatty acid esters (e.g., POE sorbitol monolaurate, POE sorbitol monooleate, POE sorbitol pentaoleate, POE sorbitol monostearate, etc.); POE glycerin fatty acid esters (e.g., POE monooleates such as POE glycerin monostearate, POE glycerin monoisostearate, POE glycerin triisostearate, etc.); POE fatty acid esters (e.g., POE distearate, POE monodioleate, POE monostearate, etc.); esters (such as PEG-20 stearate, ethylene glycol distearate, etc.); POE alkyl ethers (such as POE lauryl ether, POE oleyl ether, POE stearyl ether, POE-behenyl ether, POE-2-octyldodecyl ether, POE cholestanol ether, etc.); Pluronic (registered trademark) molded agents, etc.; POE-POP alkyl ethers (such as POE-POP cetyl ether, POE-POP-2-decyltetradecyl ether, POE-POP monobutyl ether, POE-POP hydrogenated lanolin, POE-POP glycerin ether, etc.); tetraPOE-tetraPOP ethylenediamine condensates (such as Tetronic, etc.); POE castor oil, POE hydrogenated castor oil, or derivatives thereof (such as POE hydrogenated castor oil, etc.); Examples of suitable oleic acid esters include: maltose oil, POE hydrogenated castor oil, POE hydrogenated castor oil monoisostearate, POE hydrogenated castor oil triisostearate, POE hydrogenated castor oil monopyroglutamic acid monoisostearate diester, POE hydrogenated castor oil maleic acid, etc.; POE beeswax or POE lanolin derivatives (e.g., POE sorbitol beeswax, etc.); alkanolamides (e.g., coconut oil fatty acid diethanolamide, lauric acid monoethanolamide, fatty acid isopropanolamide, etc.); POE propylene glycol fatty acid esters; POE alkylamines; POE fatty acid amides; sucrose fatty acid esters; alkylethoxydimethylamine oxide; trioleyl phosphate, sorbitan fatty acid esters (e.g., sorbitan monooleate, sorbitan monoisostearate, sorbitan sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, diglycerol sorbitan penta-2-ethylhexylate, diglycerol sorbitan tetra-2-ethylhexylate, etc.); glycerin fatty acids (for example, glycerin monocottonseed oil fatty acid, glycerin monoerucate, glycerin sesquioleate, glycerin monostearate, α,α'-oleic acid pyroglutamate, glycerin monostearate malate, polyglyceryl monoisostearate, polyglyceryl diisostearate, etc.); propylene glycol fatty acid esters (for example, propylene glycol monostearate, etc.); hydrogenated castor oil derivatives; glycerin alkyl ethers, etc. The above "POE" represents a polyethylene glycol residue (when two hydroxyl groups are bonded, it becomes a polyoxyethylene unit; when one hydroxyl group is bonded, it becomes a polyoxyethylene unit having a hydroxyl group at its terminal), and the above "POP" represents a polypropylene glycol residue (when two hydroxyl groups are bonded, it becomes a polyoxypropylene unit; when one hydroxyl group is bonded, it becomes a polyoxypropylene unit having a hydroxyl group at its terminal). POE·POP means POE or POP.

Examples of anionic surfactants according to one embodiment of the present disclosure include fatty acid soaps (e.g., sodium laurate, sodium palmitate, etc.); higher alkyl sulfate ester salts (e.g., sodium lauryl sulfate, potassium lauryl sulfate, etc.); alkyl ether sulfate ester salts (e.g., POE triethanolamine lauryl sulfate, POE sodium lauryl sulfate, etc.); N-acyl sarcosinates (e.g., sodium lauroyl sarcosinate, etc.); higher fatty acid amide sulfonates (e.g., sodium N-myristoyl-N-methyl taurate, sodium coconut oil fatty acid methyl tauride, sodium lauryl methyl tauride, etc.); phosphate ester salts (sodium POE oleyl ether phosphate, POE stearyl ether phosphate, etc.); sulfosuccinates (e.g., sodium di-2-ethylhexyl sulfosuccinate, sodium monolauroyl monoethanolamide polyoxyethylene sulfosuccinate, lauryl polypropylene glycol sodium sulfosuccinate, etc.); alkylbenzenesulfonates (for example, sodium linear dodecylbenzenesulfonate, triethanolamine linear dodecylbenzenesulfonate, linear dodecylbenzenesulfonic acid, etc.); higher fatty acid ester sulfate salts (for example, sodium hydrogenated coconut oil fatty acid glycerin sulfate, etc.); N-acylglutamates (for example, monosodium N-lauroylglutamate, disodium N-stearoylglutamate, monosodium N-myristoyl-L-glutamate, etc.); sulfated oils (for example, turmeric oil, etc.); POE alkyl ether carboxylic acids; POE alkyl allyl ether carboxylate salts; α-olefin sulfonates; higher fatty acid ester sulfonates; secondary alcohol sulfate salts; higher fatty acid alkylolamide sulfate salts; sodium lauroylmonoethanolamide succinate; ditriethanolamine N-palmitoyl aspartate; sodium caseinate; and the like.

Examples of cationic surfactants according to one embodiment of the present disclosure include alkyltrimethylammonium salts (e.g., stearyltrimethylammonium chloride, lauryltrimethylammonium chloride, etc.); alkylpyridinium salts (e.g., cetylpyridinium chloride, etc.); distearyldimethiammonium chloride dialkyldimethylammonium salts; poly(N,N'-dimethyl-3,5-methylenepiperidinium) chloride; alkyl quaternary ammonium salts; alkyldimethylbenzylammonium salts; alkylisoquinolinium salts; dialkylmorphonium salts; POE alkylamines; alkylamine salts; polyamine fatty acid derivatives; amyl alcohol fatty acid derivatives; benzalkonium chloride; benzethonium chloride; and the like.

Examples of amphoteric surfactants according to one embodiment of the present disclosure include imidazoline-based amphoteric surfactants (e.g., 2-undecyl-N,N,N-(hydroxyethylcarboxymethyl)-2-imidazoline sodium, 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, etc.); betaine-based surfactants (e.g., 2-heptadecyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, lauryldimethylaminoacetic acid betaine, alkyl betaine, amido betaine, sulfobetaine, etc.); and the like.

The content of surfactants contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure (when multiple types of surfactants are contained, the total amount of surfactants) is preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, even more preferably 0.001 parts by mass or more, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less. The content of surfactants contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.0001 parts by mass to 3 parts by mass, more preferably 0.0005 parts by mass to 1 part by mass, and even more preferably 0.001 parts by mass to 0.5 parts by mass.

The oil agent in one embodiment of the present disclosure is not particularly limited, but examples include fatty acids, fats and oils, ester oils, silicone oils, hydrocarbon oils, etc. These components may be used alone or in appropriate combinations of two or more types.

Examples of fatty acids in one embodiment of the present disclosure include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, undecylenic acid, lanolin, and isostearic acid.

Examples of oils and fats in accordance with one embodiment of the present disclosure include coconut oil, palm oil, hydrogenated palm oil, avocado oil, sesame oil, olive oil, kukui nut oil, grape kernel oil, safflower oil, almond oil, corn oil, cottonseed oil, sunflower seed oil, grape seed oil, hazelnut oil, macadamia nut oil, meadowfoam oil, and rosehip oil.

Examples of ester oils in accordance with one embodiment of the present disclosure include ethyl oleate, isopropyl myristate, isopropyl palmitate, myristyl myristate, cetyl palmitate, oleyl oleate, octyldodecyl myristate, octyldodecyl oleate, ethyl isostearate, isopropyl isostearate, cetyl 2-ethylhexanoate, cetostearyl 2-ethylhexanoate, glyceryl tri-2-ethylhexanoate, caprylic/capric triglyceride, glyceryl triisopalmitate, pentaerythritol tetra-2-ethylhexanoate, isocetyl octanoate, isostearyl octanoate, isocetyl isostearate, octyldodecyl isostearate, and octyldodecyl dimethyloctanoate.

Examples of silicone oils according to one embodiment of the present disclosure include methylpolysiloxane, highly polymerized methylpolysiloxane, methylphenylpolysiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, methylcyclopolysiloxane, alcohol-modified silicone, alkyl-modified silicone, amino-modified silicone, and epoxy-modified silicone.

Examples of hydrocarbon oils in accordance with one embodiment of the present disclosure include liquid paraffin, olive squalane, rice squalane, squalane, pristane, white petrolatum, paraffin wax, ozokerite, ceresin, and microcrystalline wax.

Examples of moisturizing agents in accordance with one embodiment of the present disclosure include glycerin, 1,3-butylene glycol, chondroitin sulfate, hyaluronic acid, mucoitin sulfate, caronic acid, atelocollagen, cholesteryl-12-hydroxystearate, sodium lactate, bile salts, dl-pyrrolidone carboxylate, short-chain soluble collagen, diglycerin (EO)PO adduct, Rosa robur extract, yarrow extract, and melilot extract.

Examples of water-soluble polymers according to an embodiment of the present disclosure include plant-based polymers (e.g., gum arabic, tragacanth gum, galactan, guar gum, carob gum, karaya gum, carrageenan, pectin, agar, quince seed (marmella), algae colloid (kasso extract), starch (rice, corn, potato, wheat), glycyrrhizic acid); microbial-based polymers (e.g., xanthan gum, dextran, succinoglucan, pullulan, etc.); animal-based polymers (e.g., collagen, casein, albumin, gelatin, etc.); starch-based polymers (e.g., carboxymethyl starch, methylhydroxypropyl starch, etc.); cellulose-based polymers (methylcellulose, ethylcellulose, methylhydroxypropylcellulose, hydrolyzed starch, etc.); Examples of suitable polymers include hydroxyethyl cellulose, sodium cellulose sulfate, hydroxypropyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, crystalline cellulose, and cellulose powder; alginic acid polymers (e.g., sodium alginate and propylene glycol alginate); vinyl polymers (e.g., polyvinyl alcohol, polyvinyl methyl ether, polyvinylpyrrolidone, and carboxyvinyl polymer (carbomer)); polyoxyethylene polymers (e.g., polyethylene glycol 20,000, 40,000, and 60,000); acrylic polymers (e.g., sodium polyacrylate, polyethyl acrylate, and polyacrylamide); polyethyleneimine; and cationic polymers.

The content of the water-soluble polymer contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.05 parts by mass or more, and preferably 3 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less. The content of the water-soluble polymer contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 to 3 parts by mass, more preferably 0.005 to 1 part by mass, and even more preferably 0.05 to 0.5 parts by mass.

Examples of antioxidants in accordance with one embodiment of the present disclosure include tocopherols, dibutylhydroxytoluene, butylhydroxyanisole, and gallic acid esters.

Examples of UV absorbers according to one embodiment of the present disclosure include benzoic acid-based UV absorbers (e.g., para-aminobenzoic acid (hereinafter abbreviated as PABA), PABA monoglycerin ester, N,N-dipropoxy PABA ethyl ester, N,N-diethoxy PABA ethyl ester, N,N-dimethyl PABA ethyl ester, N,N-dimethyl PABA butyl ester, N,N-dimethyl PABA ethyl ester, etc.); anthranilic acid-based UV absorbers (e.g., homomenthyl-N-acetylanthranilate, etc.); salicylic acid-based UV absorbers (e.g., amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, etc.); cinnamic acid-based ultraviolet absorbers (e.g., octyl cinnamate, ethyl-4-isopropyl cinnamate, methyl-2,5-diisopropyl cinnamate, ethyl-2,4-diisopropyl cinnamate, methyl-2,4-diisopropyl cinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-methoxycinnamate, octyl-p-methoxycinnamate (2-ethylhexyl-p-methoxycinnamate), 2-ethoxyethyl-p-methoxycinnamate, cyclohexyl-p-methoxycinnamate, ethyl-α-cyano-β-phenylcinnamate, 2-ethyl-α-cyano-β-phenyl cinnamate, ethylhexyl-α-cyano-β-phenylcinnamate, glyceryl mono-2-ethylhexanoyl-diparamethoxycinnamate, etc.); benzophenone-based ultraviolet absorbers (e.g., 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone, 2-ethylhexyl-4'-phenyl-benzophenone-2-carbo xylate, 2-hydroxy-4-n-octoxybenzophenone, 4-hydroxy-3-carboxybenzophenone, etc.); 3-(4'-methylbenzylidene)-d,L-camphor, 3-benzylidene-d,l-camphor; 2-phenyl-5-methylbenzoxazole; 2,2'-hydroxy-5-methylphenylbenzotriazole; 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole; 2-(2'-hydroxy-5'-methylphenylbenzotriazole; dibenzalazine; dianisoylmethane; 4-methoxy-4'-t-butyldibenzoylmethane; 5-(3,3-dimethyl-2-norbornylidene)-3-pentan-2-one; and the like.

Examples of chelating agents in accordance with one embodiment of the present disclosure include 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid tetrasodium salt, disodium edetate, trisodium edetate, tetrasodium edetate, sodium citrate, sodium polyphosphate, sodium metaphosphate, gluconic acid, phosphoric acid, citric acid, ascorbic acid, succinic acid, edetic acid, and trisodium ethylenediaminehydroxyethyltriacetate.

Examples of preservatives and antibacterial agents according to one embodiment of the present disclosure include parabens such as ethylparaben, isopropylparaben, butylparaben, and benzylparaben, and their sodium salts; benzoic acid, benzoates, alkyldiaminoethylglycine hydrochloride, photosensitizers, chlorcresol, chlorobutanol, salicylic acid, salicylates, sorbic acid and its salts, dehydroacetic acid and its salts, trichlorohydroxydiphenyl ether (also known as triclosan), phenoxyethanol, phenol, sodium lauryldiaminoethylglycine, resorcinol, zinc, Examples of the antibacterial agent include ammonia-silver composite substituted zeolite, pantothenyl ethyl ether benzoate, isopropylmethylphenol, cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride, chlorhexidine hydrochloride, orthophenylphenol, sodium orthophenylphenol, silver-copper zeolite, chlorhexidine gluconate, cresol, chloramine T, chloroxylenol, chlorphenesin, chlorhexidine, 1,3-dimethylol-5,5-dimethylhydantoin, alkylisoquinolinium bromide, thianthol, and thymol.

The content of the preservative and/or antibacterial agent contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, even more preferably 0.05 parts by mass or more, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less. The content of the preservative and/or antibacterial agent contained in 100 parts by mass of a cosmetic or quasi-drug according to one embodiment of the present disclosure is preferably 0.001 to 5 parts by mass, more preferably 0.001 to 3 parts by mass, and even more preferably 0.05 to 1 part by mass.

Fragrances according to one embodiment of the present disclosure include, for example, terpenes and terpenoids such as citral, menthol, camphor, salvinorin A, cannabinoids, hinokitiol, limonene, farnesol, and vitamin A; aromatic alcohols such as phenoxyethanol; phenols such as eugenol and shogaol; esters such as butyrate esters and propionate esters; lactones such as gamma-nonalactone and gamma-undecalactone; and aldehydes having 6 to 20 carbon atoms. In the present invention, components that can be classified as both polyhydric alcohols and fragrances are classified as fragrances.

<Others>
An embodiment of the present disclosure may include the following aspects.

[1] Crosslinked polymer particles for use in cosmetics or quasi-drugs, wherein the content of structural units derived from (meth)acrylic acid (salt) per 100 parts by mass of the crosslinked polymer is 20 parts by mass or more and 100 parts by mass or less, the volume average particle diameter D50 of the crosslinked polymer particles is 8 μm or more and 20 μm or less, and the half-value width of the volume average particle diameter is 3 μm or more and less than 20 μm.

[2] Crosslinked polymer particles for cosmetics or quasi-drugs described in [1], having a turbidity of 50% or less.

[3] Crosslinked polymer particles for cosmetics or quasi-drugs described in [1] or [2], in which the crosslinked polymer is crosslinked with a compound having two or more ethylenically unsaturated groups in one molecule.

[4] A cosmetic or quasi-drug product using the crosslinked polymer particles described in any one of [1] to [3].

[5] A cosmetic or quasi-drug described in [4] that is for use on the skin.

[6] The cosmetic or quasi-drug described in claim 4 or 5, further comprising an inorganic white pigment.

[7] A method for producing crosslinked polymer particles for cosmetics or quasi-drugs, wherein the crosslinked polymer is obtained by polymerizing 20 parts by mass or more and 100 parts by mass or less of (meth)acrylic acid (salt) per 100 parts by mass of total monomers, and the volume average particle diameter of the crosslinked polymer is 8 μm or more and 20 μm or less, and the half-value width of the volume average particle diameter is 3 μm or more and less than 20 μm.

[8] The method for producing crosslinked polymer particles for cosmetics or quasi-drugs described in [7], wherein a compound having two or more ethylenically unsaturated groups in one molecule is used in the polymerization.

[9] A method for producing crosslinked polymer particles for cosmetics or quasi-drugs according to [8] or [9], wherein the crosslinked polymer is pulverized after the polymerization.

[10] A method for producing crosslinked polymer particles for cosmetics or quasi-drugs described in [9], in which the crosslinked polymer is dried between the polymerization and the grinding.

[11] A method for producing crosslinked polymer particles for cosmetics or quasi-drugs according to any one of [7] to [10], in which 50 parts by mass or more and 100 parts by mass or less of (meth)acrylic acid (salt) and/or 50 parts by mass or more and 80 parts by mass or less of acrylamide are polymerized per 100 parts by mass of all monomers.

[12] A method for producing crosslinked polymer particles for cosmetics or quasi-drugs described in any one of [7] to [11], further comprising adding an inorganic white pigment to the crosslinked polymer.

The present invention will now be described in further detail based on examples, but the present invention is not limited to these examples.

Production Example [Production Example 1]
A reaction solution was prepared by dissolving 4.79 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added: 9) as an internal crosslinking agent in 5,500 g of a 33 wt % aqueous solution of sodium acrylate with a neutralization rate of 75 mol %. Next, this reaction solution was degassed for 30 minutes under a nitrogen gas atmosphere (dissolved oxygen in the reaction solution was expelled by blowing nitrogen gas into the reaction solution for 30 minutes). The reaction solution was then supplied to a reactor formed by attaching a lid to a jacketed stainless steel double-arm kneader with two sigma blades and an internal volume of 10 L, and the system was purged with nitrogen gas while maintaining the reaction solution at 25 ° C. Subsequently, while stirring the reaction solution, 2.4 g of ammonium persulfate and 0.12 g of L-ascorbic acid were added as polymerization initiators, and polymerization began approximately 1 minute later. Polymerization was then carried out at 25 to 90 ° C., and the reaction was terminated 40 minutes after the start of polymerization, and a hydrogel-like crosslinked polymer was extracted.
The resulting hydrogel crosslinked polymer was fragmented to a diameter of about 5 mm. This fragmented hydrogel crosslinked polymer (particulate hydrogel) was spread on a 50-mesh wire netting (opening size: 300 μm) and dried with hot air at 170° C. for 70 minutes to obtain a dried polymer.

The resulting dried polymer was then pulverized using a vibration mill and classified using a JIS standard sieve with an opening of 850 μm to obtain the sieve-passing material. This series of operations yielded pulverized intermediate (1).

[Production Example 2]
100 parts by weight of the pulverized intermediate (1) obtained in Production Example 1 was mixed with an aqueous surface cross-linking agent solution consisting of 0.7 parts by weight of propylene glycol, 0.02 parts by weight of ethylene glycol diglycidyl ether, 2 parts by weight of water, and 0.7 parts by weight of ethyl alcohol. The mixture was heat-treated at 185°C for 40 minutes to obtain a surface-cross-linked pulverized intermediate (1). Next, 0.3 g of hydrophilic silicon dioxide (trade name: Aerosil 200 (average particle size of primary particles: approximately 12 nm); manufactured by Nippon Aerosil Co., Ltd.) as an inorganic powder was added to 100 g of the surface-cross-linked pulverized intermediate (1) and mixed (dry blended) to obtain a pulverized intermediate (2).

[Production Example 3]
7.5 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added: 9) was dissolved in 5,500 g of an aqueous solution of sodium acrylate (monomer concentration: 38% by mass) having a neutralization rate of 75 mol% to prepare a reaction solution. The reaction solution was then fed into a reactor formed by attaching a lid to a jacketed stainless steel double-arm kneader with an internal volume of 10 L and two sigma-type blades. The system was purged with nitrogen gas while maintaining the reaction solution at 30°C to remove dissolved oxygen. Subsequently, while stirring the reaction solution, 29.8 g of a 10% by mass aqueous solution of sodium persulfate and 1.5 g of a 1% by mass aqueous solution of L-ascorbic acid were added, and polymerization began approximately 1 minute later. The polymerization peak temperature reached 86°C 17 minutes after the start of polymerization, and the hydrogel-like crosslinked polymer was removed 60 minutes after the start of polymerization. The obtained hydrogel-like crosslinked polymer was fragmented into particles of approximately 1 to 4 mm.

This finely divided hydrogel crosslinked polymer (particulate hydrogel) was spread on a 50 mesh (opening size 300 μm) wire netting and dried with hot air at 160° C. for 60 minutes to obtain a dried polymer.
The resulting dried polymer was then pulverized using a roll mill and further classified using a JIS standard sieve with a mesh size of 450 μm. Particles with a size of 450 μm or larger were again pulverized using a roll mill and classified using a JIS standard sieve with a mesh size of 450 μm, and the particles passing through the two sieves were combined. This series of operations yielded a pulverized intermediate (3).

[Production Example 4]
100 parts by mass of the pulverized intermediate (3) obtained in Production Example 3 was mixed with 0.7 parts by mass of a surface-crosslinking agent aqueous solution consisting of 0.1 parts by mass of ethylene glycol diglycidyl ether, 0.3 parts by mass of propylene glycol, and 0.3 parts by mass of water. The mixture was heat-treated for 20 minutes in a mortar mixer heated to 210°C to obtain a surface-crosslinked pulverized intermediate (3). 100 parts by mass of the obtained surface-crosslinked pulverized intermediate (3) was spray-mixed with a mixed solution consisting of 0.01 parts by mass of sodium diethylenetriaminepentaacetate, 0.1 parts by mass of a 15% by mass aqueous solution of leaf extract of a plant of the Theaceae family (product name: FS-80MO, sold by Shirai Matsushin Pharmaceutical Co., Ltd. (location: 37-1 Ukawa, Minakuchi-cho, Koka-gun, Shiga Prefecture)), and 3 parts by mass of water. The obtained mixture was heated and cured at 60°C for 1 hour while maintaining a water content of 3% by mass, and then passed through a wire mesh with an opening of 600 μm. To 100 parts by mass of the obtained polymer composition, 0.3 parts by mass of finely divided silicon dioxide (trade name: Aerosil 200) as an inorganic powder was added and mixed (dry blended) to obtain a pulverized intermediate (4).

[Production Example 5]
A 2-liter polypropylene container was charged with 421.7 g of acrylic acid, 2.4 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added: 9) as an internal crosslinking agent, 11.3 g of a 1.0 wt% aqueous solution of trisodium diethylenetriaminepentaacetic acid, 140.4 g of a 48.5 wt% aqueous solution of sodium hydroxide, 4.4 g of a 1.0 wt% aqueous solution of polyoxyethylene (20) sorbitan monostearate (manufactured by Kao Corporation), and 390.3 g of deionized water (ion-exchanged water), and mixed to prepare an aqueous monomer solution (a'). The temperature of the aqueous monomer solution (a') rose to 62.9°C due to the heat of neutralization in the first stage immediately after preparation. Next, the aqueous monomer solution (a') was cooled with stirring. When the liquid temperature reached 38°C, 211.9 g of a 48.5 wt% aqueous sodium hydroxide solution adjusted to 40°C was added to the aqueous monomer solution (a') and mixed to prepare an aqueous monomer solution (a). At this time, the temperature of the aqueous monomer solution (a) rose to 81.7°C due to the heat of neutralization generated in the second stage immediately after preparation. Immediately after starting to mix the 48.5 wt% aqueous sodium hydroxide solution, a precipitate was observed, but it gradually dissolved to form a transparent, homogeneous solution. Next, nitrogen gas was introduced into the aqueous monomer solution (a) at 0.1 L/min for 5 seconds using a Kinoshita glass bowl filter (filter particle No. 4/Kinoshita Rika Kogyo Co., Ltd.). Next, 17.6 g of a 4.0 wt% aqueous sodium persulfate solution was added to the stirred aqueous monomer solution (a), and the mixture was immediately poured into a stainless steel bat-shaped container (bottom 340 x 340 mm, height 25 mm, inner surface: Teflon (registered trademark) coated) in an open-to-air system. The time from the start of the second-stage neutralization to pouring the aqueous monomer solution (a) into the bat-shaped container was 55 seconds, and the bat-shaped container was heated using a hot plate (NEOHOTPLATEHI-1000/Iuchi Seieido Co., Ltd.) until the surface temperature reached 40°C. The polymerization reaction began 60 seconds after the aqueous monomer solution (a) was poured into the bat-shaped container. The polymerization reaction proceeded by expanding and foaming in all directions while generating steam, and then contracted to a size slightly larger than the bat-shaped container. Three minutes after the start of the polymerization reaction, the hydrogel-like crosslinked polymer (hereinafter referred to as "hydrogel") was removed. This series of operations was carried out in an open-air system. The peak temperature during polymerization was 108°C.

The hydrogel obtained from the polymerization reaction was crushed using a meat chopper (HL-3225N, plate aperture: 8.0 mm/Remacom Co., Ltd.) to produce a particulate hydrogel. The hydrogel was added at a rate of 230 g/min, and deionized water adjusted to 90°C was added at 50 g/min while the hydrogel was being added. The resulting particulate hydrogel was spread on a stainless steel wire mesh with an 850 μm mesh size and dried by ventilating with hot air at 180°C for 30 minutes to obtain a dried polymer. The dried polymer obtained from the drying operation was then crushed using a roll mill (WL-type roll crusher/Inoguchi Giken Co., Ltd.) and classified using a JIS standard sieve with an aperture of 710 μm to obtain the sieve-passing material. This series of operations yielded the crushed intermediate (5).

[Production Example 6]
A surface crosslinking agent solution consisting of 0.3 parts by weight of ethylene carbonate, 0.6 parts by weight of propylene glycol, 3.0 parts by weight of deionized water (ion-exchanged water), and 0.001 parts by weight of polyoxyethylene (20) sorbitan monostearate (Kao Corporation) (10 ppm relative to the pulverized intermediate (5)) was added to 100 parts by weight of the pulverized intermediate (5) obtained in Production Example 5 and mixed uniformly. Thereafter, the mixture was heat-treated at 208°C for 40 minutes to perform surface crosslinking.

After the heat treatment, the resulting surface-crosslinked pulverized intermediate (5) was crushed until it passed through a JIS standard sieve with a mesh size of 850 μm, thereby obtaining pulverized intermediate (6).

[Production Example 7]
A reaction solution was prepared by dissolving 2.83 g of trimethylolpropane triacrylate as an internal crosslinking agent in 5,500 g of a 33 wt % aqueous solution of sodium acrylate with a neutralization rate of 75 mol %. Next, this reaction solution was degassed for 30 minutes under a nitrogen gas atmosphere (nitrogen gas was blown into this reaction solution for 30 minutes to expel dissolved oxygen in the reaction solution). Next, the reaction solution was supplied to a reactor formed by attaching a lid to a jacketed stainless steel double-arm kneader with two sigma-type blades and an internal volume of 10 L, and the system was purged with nitrogen gas while maintaining the reaction solution at 25 ° C. Next, while stirring the reaction solution, 2.4 g of ammonium persulfate and 0.12 g of L-ascorbic acid were added as polymerization initiators, and polymerization began approximately 1 minute later. Then, polymerization was carried out at 25 to 90 ° C., and the reaction was terminated 40 minutes after the start of polymerization, and a hydrogel-like crosslinked polymer was taken out.

The resulting hydrogel-like cross-linked polymer was broken down into particles approximately 5 mm in diameter. This broken down hydrogel-like cross-linked polymer (particulate hydrogel) was spread on a 50-mesh wire mesh (opening size 300 μm) and dried with hot air at 170°C for 70 minutes to obtain a dried polymer.

The resulting dried polymer was then pulverized using a vibration mill and classified using a JIS standard sieve with an opening of 850 μm to obtain the sieve-passing material. This series of operations yielded pulverized intermediate (7).

[Production Example 8]
An aqueous surface crosslinking agent solution consisting of 0.7 parts by weight of propylene glycol, 0.02 parts by weight of ethylene glycol diglycidyl ether, 2 parts by weight of water, and 0.7 parts by weight of ethyl alcohol was mixed with 100 parts by weight of the pulverized intermediate (7) obtained in Production Example 7. The mixture was heat-treated at 185°C for 40 minutes to obtain a pulverized intermediate (8).

[Example]
Each of the pulverized intermediates (1) to (8) was pulverized by one of the pulverization methods described below to obtain finely pulverized crosslinked polymer particles 1 to 8.

[Pulverization Example 1]
The intermediate product was finely pulverized using a supersonic jet pulverizer LJ-3 (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) at a pulverization pressure of 0.6 MPa.

[Pulverization Example 2]
The intermediate product was finely pulverized using a Super Jet Mill SJ-500 (manufactured by Nisshin Engineering Co., Ltd.) at a pulverization pressure of 0.6 MPa.

[Pulverization Example 3]
The pulverized intermediate was finely pulverized using a Silfeed Mill SIW-10 (manufactured by Dalton Co., Ltd.) [Pulverization Example 4]
400 g of the ground intermediate product and 3 kg of 10 mm SUS balls were placed in a SUS pot mill (volume: 3 L) and milled at 30 rpm for 24 hours to finely grind the mixture.

The grinding intermediates and grinding methods used to prepare each of the finely ground crosslinked polymer particles are listed in Tables 1 and 2.

Comparative Production Example 1
Crosslinked polymer particles were obtained by reverse phase suspension polymerization with reference to Production Examples 2 to 7 of JP 2015-151336 A, and comparative crosslinked polymer particles 1 were produced without a pulverization step. The volume average particle diameter of the obtained comparative crosslinked polymer particles 1 was 26.51 μm, and the half width was 21.18 μm.

Comparative Production Example 2
Crosslinked polymer particles were obtained by reverse phase suspension polymerization with reference to Examples 1 to 11 of Japanese Patent No. 3023110, and comparative crosslinked polymer particles 2 were produced without a pulverization step. The volume average particle diameter of the obtained comparative crosslinked polymer particles 2 was 7.59 μm, and the half width was 2.51 μm. Turbidity and viscosity measurements, as well as sensory evaluation, were carried out by adjusting a 1% by mass aqueous solution of the produced comparative crosslinked polymer particles 2 to a pH of 5 to 8 with a 10% aqueous NaOH solution.

[Method for measuring volume average particle size and half-value width]
Measurement was performed using a laser diffraction scattering particle size distribution analyzer LA-950 manufactured by HORIBA Co., Ltd. Ethyl acetate was used as the circulating solvent during measurement, and the refractive index of the dispersion was 1.59, and the refractive index of the dispersion medium was 1.371. The median diameter (μm) was calculated from the particle size distribution on a volume basis obtained by measurement, and this was taken as the volume average particle diameter D50.

The half-value width was calculated based on the particle size distribution graph obtained from the volume average particle size measurement. Specifically, the half-value frequency was calculated from the maximum frequency value, and the particle size at half-value was calculated from the approximate curve equation for the region including the half-value. The difference between the particle sizes at the two points was taken as the half-value width.

[Method for measuring turbidity]
Measurement was performed using a haze meter NDH7000 manufactured by Nippon Denshoku Co., Ltd. A 1% aqueous solution of the crosslinked polymer particles was prepared and filled into a quartz cell with an optical path length of 10 mm, and measurement was performed at a measurement temperature of 25°C using a haze meter NDH7000 manufactured by Nippon Denshoku Co., Ltd.

[Viscosity measurement method]
Each crosslinked polymer particle was blended with purified water to prepare a blend of 1% by mass, and the viscosity was measured using a B-type viscometer TVB-10 manufactured by Toki Sangyo Co., Ltd. under the conditions of a rotor TM4, a rotation speed of 1.5 rpm or 6 rpm, a measurement time of 60 seconds, and a temperature of 25°C.

[Sensory evaluation using crosslinked polymer blends]
The average particle size, half-value width, turbidity, and viscosity of crosslinked polymer particles 1 to 8 and comparative crosslinked polymer particles 1 to 2, as well as the results of sensory evaluation by expert panelists when each crosslinked polymer particle and comparative crosslinked polymer particle was applied to the skin, are shown in Tables 3 and 4.

The sensory evaluation was carried out as follows. A 1% by mass aqueous solution of each of the obtained crosslinked polymer particles was prepared, and a sensory evaluation was carried out by a panel of experts when the solution was applied to the inside of the forearm. The spreadability upon application, compatibility with the skin, moisture, stickiness, stickiness upon drying, and squeaking sensation were scored on a 5-point scale (5: very good, 4: good, 3: normal, 2: bad, 1: very bad), and the average value (rounded up) was used as the overall evaluation.

As shown in Tables 3 and 4, the crosslinked polymer particles 1 to 8, each having a volume average particle size of 8 μm or more and 20 μm or less and a half-value width of 3 μm or more and less than 20 μm, were found to have an excellent feel when applied to the skin in sensory evaluation. In particular, they were found to be excellent in that they were free from slimy feeling when applied and from sticky or squeaky feeling when dried.

Furthermore, for comparative crosslinked polymer particles 1, which were used as a comparison product and had a volume average particle diameter of more than 20 μm and a half-value width of 20 μm or more, sensory evaluation revealed that they did not blend well with the skin when applied, and were slimy, sticky when drying, and had a squeaky feel, making them unsuitable for use. Furthermore, comparative crosslinked polymer particles 2, which had a volume average particle diameter of less than 8 μm and a half-value width of less than 3 μm, were found to have an unsuitable feel for use in that they were slimy when applied to the skin and sticky when drying, making them unsuitable for use.

[Suncare preparation containing crosslinked polymer particles]
Crosslinked polymer particles 1 to 8, comparative crosslinked polymer particles 1 to 2, purified water, and DIS-AB-10W ( titanium dioxide , hydrated silica, hydrogen dimethicone, water, BG, PEG-9 dimethicone; Sakai Chemical Industry Co., Ltd.) were blended to prepare sun care preparations incorporating each crosslinked polymer particle. The formulations of the sun care preparations are shown in Tables 5 and 6 below.

The results of appearance evaluation and sensory evaluation of sun care preparations 1 to 10 prepared according to the formulations shown in Tables 5 and 6 are shown in Tables 7 and 8.

As shown in Tables 7 and 8, it was revealed that suncare preparations 1 to 8, which contain crosslinked polymer particles 1 to 8 having a volume average particle size of 8 μm or more and 20 μm or less and a half-value width of 3 μm or more and less than 20 μm, have excellent dispersibility of titanium dioxide, have a unique appearance like whipped cream, and are smooth to the touch when applied.

In addition, Suncare Formulation 9, which contains comparative crosslinked polymer particles 1, which have a volume average particle size of more than 20 μm and a half-value width of 20 μm or more, used as a comparison product, yields a gel-like dispersion, but tends to be sticky when applied. Furthermore, Suncare Formulation 10, which contains comparative crosslinked polymer particles 2, which have a volume average particle size of less than 8 μm and a half-value width of less than 3 μm, yields a gel-like dispersion, but was found to have a strong squeaky feeling when applied.

[Evaluation of UV resistance by adding a chelating agent]
Each crosslinked polymer particle was blended with purified water to prepare a formulation at 1% by mass. Similarly, comparative crosslinked polymer particles 1 were blended with purified water to prepare a formulation at 0.4% by mass. Comparative crosslinked polymer particles 2 were also blended with a 0.4% by mass aqueous solution, and a formulation was prepared by adjusting the pH of the 0.4% by mass aqueous solution to 5 to 8 with a 10% NaOH aqueous solution. The stability of each blend over time under sunlight was evaluated by measuring the viscosity using a Toki Sangyo Co., Ltd. B-type viscometer TVB-10 with a rotor TM4 at a rotation speed of 6 rpm, a measurement time of 60 seconds, and a temperature of 25°C. The results are shown in Figure 1.

As shown in Figure 1, the viscosity of each crosslinked polymer particle formulation and Comparative Crosslinked Polymer Particle 1 formulation reached zero within seven days. On the other hand, Comparative Crosslinked Polymer Particle 2 formulation showed a decrease in viscosity over time, but still maintained a viscosity of approximately 10,000 mPa·s even after 30 days. Each of the above formulations was blended with 0.1% chelating agent EDTA·2Na, and stability over time under sunlight was evaluated using the same method. The results are shown in Figure 2.

As shown in Figure 2, each crosslinked polymer particle formulation and the comparative crosslinked polymer particle 2 formulation maintained their viscosity at the start of measurement, demonstrating that UV resistance is improved by the effect of the chelating agent. On the other hand, the comparative crosslinked polymer particle 1 formulation lost its viscosity when 0.1% of the chelating agent EDTA-2Na was added.

[Evaluation of stability under fluorescent light with the addition of a chelating agent]
Each crosslinked polymer particle was blended with purified water to prepare a formulation at 1% by mass. Similarly, comparative crosslinked polymer particles 1 were blended with purified water to prepare a formulation at 0.4% by mass, and comparative crosslinked polymer particles 2 were blended by adjusting a 0.4% by mass aqueous solution to a pH of 5 to 8 with a 10% NaOH aqueous solution. Stability over time under fluorescent light was evaluated by measuring the viscosity using a Toki Sangyo Co., Ltd. B-type viscometer TVB-10 with a rotor TM4, a rotation speed of 6 rpm, a measurement time of 60 seconds, and a temperature of 25°C. The results are shown in Figure 3.

As shown in Figure 3, each crosslinked polymer particle formulation and Comparative Crosslinked Polymer Particle 1 formulation showed a decrease in viscosity over time. On the other hand, Comparative Crosslinked Polymer Particle 2 formulation maintained its viscosity before and after the start of the test, demonstrating high stability.

The chelating agent EDTA-2Na was added to each of the above formulations at a concentration of 0.1%, and the stability over time under fluorescent light was evaluated using the same method. The results are shown in Figure 4.

As shown in Figure 4, each crosslinked polymer particle formulation and the comparative crosslinked polymer particle 2 formulation maintained their viscosity at the start of the measurement, demonstrating that the effect of the chelating agent improves light resistance under fluorescent light. On the other hand, the comparative crosslinked polymer particle 1 formulation lost its viscosity when 0.1% of the chelating agent EDTA-2Na was added.

[Lotion]
Using the crosslinked polymer particles 1 obtained, a lotion having the formulation shown in Table 9 below was prepared.

(Preparation method)
After mixing components 2 to 4, component 1 was added and dispersed for 1 minute at 500 rpm using a Three-One Motor. Then, components 5 and 6 were added in order and dispersed for 2 minutes at 500 rpm using a Three-One Motor, and finally component 7 was added and dispersed for 15 minutes at 500 rpm using a Three-One Motor to obtain a lotion. This lotion had excellent moisturizing power and long-lasting effect.

[Gel]
Using the obtained crosslinked polymer particles 2, a gel having the formulation shown in Table 10 below was prepared.

(Preparation method)
Component 2 was added to component 1 and dispersed for 30 minutes at 700 rpm using a Three-One motor. Components 3 to 5 were uniformly dispersed, added to the mixture of components 1 and 2, and then mixed by hand. After thorough uniform mixing, components 6 and 7 were added in sequence and mixed uniformly by hand to obtain a gel. This gel had excellent moisturizing power and long-lasting properties.

[Emulsion]
Using the obtained crosslinked polymer particles 3, an emulsion having the formulation shown in Table 11 below was prepared.

(Preparation method)
Component 15 in Table 11 was added to a portion of component 16 and stirred to form a viscous liquid (Part A). Next, components 1 to 8 were heated to approximately 70°C and dissolved (Part B). Components 9 to 14 and the remaining component 16 were heated to approximately 70°C and dissolved (Part C). Part C was added to Part B with stirring to emulsify, and then cooled to approximately 50°C. Part A was added and stirred until uniform, yielding an emulsion. This emulsion was excellent in imparting a moist feeling.

[Beauty serum]
Using the obtained crosslinked polymer particles 4, a cosmetic liquid having the formulation shown in Table 12 below was prepared.

(Manufacturing method)
First, the components listed in Table 12 were mixed uniformly for each section to obtain mixtures (Parts A to C). Parts A and C were dissolved at 80°C. Part B was gradually added to Part A while stirring and mixed, and then Part C was added and stirred to make uniform, followed by cooling to obtain a serum. This serum had a high moisturizing effect, softened the skin, and maintained a fresh, smooth, and moisturized feel for a long time.

[Introducing serum]
Using the obtained crosslinked polymer particles 5, an introduction beauty serum having the formulation shown in Table 13 below was prepared.

(Manufacturing method)
The components listed in Table 13 were mixed uniformly for each section to obtain a mixture (Parts A and C). Part B was gradually added to Part A while stirring and mixed, and then Parts C to H were added in order and stirred until uniform, obtaining an introduction serum. This introduction serum had a high penetration and moisturizing effect, softened the skin, and kept the skin fresh, smooth, and moisturized for a long time.

[Massage cream]
Using the obtained crosslinked polymer particles 6, a massage cream having the formulation shown in Table 14 below was prepared.

(Preparation method)
Components 1 to 17 in Table 14 were heated to approximately 70°C and uniformly dissolved (Part A). Next, components 18 to 22 were heated to approximately 70°C and uniformly dissolved (Part B). Part B was added to Part A with stirring, and the mixture was emulsified and then cooled to obtain a massage cream. This massage cream had a high massage effect and was excellent in providing a moist feeling.

[Emollient cream]
Using the obtained crosslinked polymer particles 7, an emollient cream having the formulation shown in Table 15 below was prepared.

(Preparation method)
Components 1 to 10 in Table 15 were added and heated to approximately 80°C until dissolved (Part A). Components 11 to 15 were placed in a separate container and heated to approximately 80°C until uniformly dissolved (Part B). Part B was added to Part A, emulsified using a homomixer, and then cooled to 40°C to obtain an emollient cream. This emollient cream was excellent in imparting a moist feeling.

[Anti-aging cream]
Using the obtained crosslinked polymer particles 8, an anti-aging cream having the formulation shown in Table 16 below was prepared.

(Manufacturing method)
The components of Part A were heated to about 80°C and dissolved uniformly (Part A). The components of Part B were heated to about 80°C and dissolved uniformly (Part B). Part B was gradually added to Part A while stirring with a homomixer at about 80°C, and after emulsification, the mixture was mixed uniformly and cooled to about 30°C to obtain an anti-aging cream. This anti-aging cream spreads well and has an excellent effect of imparting a moist feeling.

[Base cream]
Using the obtained crosslinked polymer particles 1, a base cream having the formulation shown in Table 17 below was prepared.

(Preparation method)
The components listed in Table 17 were mixed uniformly for each section to obtain mixtures (Parts A to C). Part A was heated to 80°C, and Part B was added and mixed. Part C was added to the obtained mixture, emulsified, and then mixed uniformly. After stirring, the mixture was cooled to 40°C to obtain a base cream. This base cream spreads well, provides good foundation adhesion and staying power, and provides a smooth feel.

[Foundation]
Using the obtained crosslinked polymer 2, a foundation having the formulation shown in Table 18 below was prepared.

(Preparation method)
The components were mixed uniformly under high speed stirring to obtain a foundation, which had excellent color development and a moist feel.

[lipstick]
Using the obtained crosslinked polymer 3, a lipstick having the formulation shown in Table 19 below was prepared.

(Preparation method)
Components 11 to 14 in Table 19 were kneaded with components 1 and 2 (Part A). Components 3 to 10 were added to a separate container and heated to approximately 80°C to dissolve (Part B). Part A was added to Part B at approximately 80°C, and after dissolution, the mixture was rapidly cooled to obtain a lipstick. This lipstick had a fresh, moist feel and good adhesion.

[Lip gloss]
Using the obtained crosslinked polymer 4, a lip gloss having the formulation shown in Table 20 below was prepared.

(Preparation method)
Components 1 and 2 in Table 20 were heated to 100-110°C and dissolved uniformly. Components 3 to 6 were then added and dissolved uniformly at approximately 80°C to obtain a lip gloss. This lip gloss had a moisturizing taste and good adhesion.

[mascara]
Using the obtained crosslinked polymer particles 5, a mascara having the formulation shown in Table 21 below was produced.

(Preparation method)
Component 1 was added to component 9 in Table 21 and dispersed using a homomixer, followed by addition of component 3, which was heated and maintained at 70°C (aqueous phase). The other components were mixed, heated, and maintained at 70°C (oil phase). The aqueous phase was added to the oil phase, and the mixture was uniformly emulsified and dispersed using a homomixer to obtain the desired mascara. This mascara had good adhesion, a pleasant feel when used, and good stability.

[Eyeshadow]
Using the obtained crosslinked polymer particles 6, an eye shadow was produced according to the formulation shown in Table 22 below.

(Preparation method)
Components 1 to 3 in Table 22 were mixed in a blender and then processed in a pulverizer (powder portion). Components 11 to 16 were heated and dissolved at 70 to 75°C (aqueous phase portion). Furthermore, components 4 to 10 were heated and dissolved at 70 to 80°C (oil phase portion). The powder portion was added to the aqueous phase portion and mixed with stirring. To this, the oil phase portion was added with stirring, dispersed using a homomixer, and cooled to room temperature with stirring to obtain the desired eye shadow. This emulsified eye shadow had good adhesion, a good feel when used, and also had good emulsion stability.

[shampoo]
Using the obtained crosslinked polymer particles 7, a shampoo having the formulation shown in Table 23 below was prepared.

(Preparation method)
Components 1 to 5 in Table 23 were heated to about 80°C and dissolved uniformly (Part A). Next, components 6 to 8 were heated to about 80°C and dissolved uniformly (Part B). Part B was added to Part A and the mixture was stirred and mixed at about 80°C until uniform, and then cooled to obtain a shampoo. This shampoo was able to impart a moist feeling to hair and was excellent in imparting a smooth feel to the hair.

[Treatment]
Using the obtained crosslinked polymer particles 8, a treatment according to the formulation in Table 24 below was prepared.

(Preparation method)
Components 1 to 6 in Table 24 were heated to approximately 80°C and uniformly dissolved (Part A). Next, components 7 to 11 were heated to approximately 80°C and uniformly dissolved (Part B). Part B was added to Part A and mixed uniformly with stirring, and then cooled to room temperature to obtain a treatment. This treatment was able to impart a moist and soft feel to hair.

[Moisturizing Rinse]
Using the obtained crosslinked polymer particles 1, a moisturizing rinse was prepared according to the formulation in Table 25 below.

(Preparation method)
Components 1 to 12 in Table 25 were heated to approximately 80°C and dissolved (Part A). In a separate container, components 14 and 15 were heated to approximately 80°C and dissolved (Part B). Part B was gradually added to Part A while stirring, and mixed uniformly. Component 13 was then added, and the mixture was stirred and then rapidly cooled to obtain a moist rinse. This moist rinse was a rinse that was not sticky, imparted a moist feeling to hair, and made it easy to run your fingers through.

[Straight perm agent (cationic type)]
Using the obtained crosslinked polymer particles 2, first and second liquids of a straight permanent agent (cationic type) having the formulations shown in Tables 26 (first liquid) and 27 (second liquid) below were prepared.

(Preparation method: 1 liquid)
Most of the component 15 in Table 26 was heated to about 80°C (Part A). Components 1 to 8 were added to a separate container.
The remaining ingredients in component 15 were added to a separate container, which was then heated and dissolved (Part B). The remainder of component 15 and ingredients 9 to 13 were added to a separate container and dissolved uniformly (Part C). Part B was added to Part A, and the mixture was stirred and mixed. At approximately 45°C, Part C was added and mixed uniformly. After cooling to room temperature, component 14 was added to obtain a first solution of a straight perm agent.

(Preparation method: 2 liquids)
Components 1 to 7 in Table 27 were mixed and heated to approximately 70°C and dissolved (Part A). Most of component 11 was placed in a separate container and heated to approximately 70°C, and components 8 and 9 were added and dissolved (Part B). The remaining portion of component 11 was placed in a separate container and heated to approximately 60°C, and component 10 was added and dissolved (Part C). Part B was added to Part A at approximately 70°C and stirred until the viscosity increased. The mixture was cooled to 60°C, and Part C was added while stirring and mixed uniformly. After the temperature was reduced to approximately 50°C, the mixture was rapidly cooled to obtain a second solution of the straight perm agent. The resulting straight perm solution had high adhesion to hair and strong setting power, allowing for a reliable straight perm.

[Hair bleach (two-component)]
Using the obtained crosslinked polymer particles 3, hair bleaches (two-component type) having the formulations shown in Tables 28 and 29 below were prepared.

(Preparation method: 1st agent)
The components listed in Table 28 were stirred and mixed uniformly to obtain a first agent of a hair bleaching agent.

(Preparation method: 2nd agent)
The components listed in Table 29 were mixed uniformly and the pH was adjusted to 3.5 to 4.0 with citric acid to obtain two hair bleaching agents.

(Preparation method: hair bleach)
A hair bleaching agent was obtained by blending the first and second agents obtained in the following blending ratio.

(Mixing ratio)
1st agent:2nd agent = 1:7.

This hair bleach (two-component type) was a bleach that, when applied to hair, reduced the feeling of damage to the hair after bleaching and gave the hair a good feel, such as softness, moistness, and smoothness.

[Oxidative hair dye]
Using the obtained crosslinked polymer particles 4, oxidation hair dyes (two-component type) having the formulations shown in Tables 30 and 31 below were prepared.

(Preparation method: 1st agent)
The components listed in Table 30 were mixed uniformly to obtain a first agent of an oxidation hair dye.

(Preparation method: 2nd agent)
The components listed in Table 31 were mixed uniformly and the pH was adjusted to 3.5 to 4.0 with citric acid to obtain two oxidative hair dye agents.

(Preparation method: oxidation hair dye)
An oxidation hair dye was obtained by blending the first and second agents obtained in the following blending ratio.

(Mixing ratio)
1st drug:2nd drug = 1:1.

This oxidation hair dye (two-component type) was an oxidation hair dye that, when applied to hair, reduced the feeling of damage to the hair after dyeing and gave the hair a good feel, such as softness, moistness, and smoothness.

[Curling agent]
Using the obtained crosslinked polymer particles 5, curling agents having the formulations shown in Tables 32 and 33 below were produced.

(Preparation method: 1 liquid)
Components 1 to 3 were added to a portion (20%) of component 16 in Table 32 and dissolved. Components 14 and 15 had been dissolved in a separate container (10%), and this was added at approximately 40°C to form a uniform solution (Part A). The remainder of component 16 was heated to approximately 75°C in a separate container (Part B). Components 8 to 13 were then placed in a separate container and heated to approximately 75°C to form a uniform solution (Part C). Part B was added to Part C to emulsify the mixture and thoroughly stirred. The mixture was then cooled to 40°C, and Part A was added and stirred uniformly. Next, component 7 was added and stirred, followed by components 5 and 6, and then component 4 was added and stirred uniformly. The pH was adjusted to 9.0 to 9.5 to obtain the desired curling agent solution 1.

(Preparation method: 2 liquids)
Components 4 to 7 in Table 33 were heated to about 80°C and dissolved (Part A). A portion of Component 9 (70%) and Components 1 and 8 were added to a separate container and heated to about 80°C and dissolved (Part B). The remainder of Component 9 and Components 2 and 3 were added to a separate container and heated to about 50°C and dissolved (Part C). Part B was added to Part A, and the mixture was uniformly mixed and stirred to emulsify. Once the temperature reached 40°C, Part C was added and mixed well, and the mixture was adjusted to a pH of 6.5 to 6.8 at room temperature, yielding two solutions of the desired curling agent.

By applying the first and second liquids of the curling agent thus prepared to hair, curls could be obtained with good flexibility, smoothness, moist texture and a good finish.

[Hair cream]
Using the obtained crosslinked polymer particles 6, a hair cream having the formulation shown in Table 34 below was prepared.

(Preparation method)
Components 1 to 6 in Table 34 were heated to approximately 80°C and dissolved (Part A). Components 7 to 10 were added to a separate container, heated to approximately 80°C, and dissolved (Part B). Part B was added to Part A and mixed with stirring to obtain a hair cream. This hair cream was glossy, not sticky, retained moisture in the hair, and provided a smooth feel.

[Leave-on treatment]
Using the obtained crosslinked polymer particles 7, a leave-on treatment (for hair) was prepared according to the formulation in Table 35 below.

(Preparation method)
Components 1 to 7 in Table 35 were heated to about 80°C and dissolved (Part A). Components 8 and 9 were placed in a separate container and heated to about 80°C and dissolved (Part B). Part B was gradually added to Part A and mixed uniformly to obtain a leave-on treatment (for hair). This leave-on treatment (for hair) had a smooth feel and was able to impart softness and smoothness to hair. It also had good stability.

[Hair Essence]
Using the obtained crosslinked polymer particles 8, a hair essence having the formulation shown in Table 36 below was prepared.

(Preparation method)
Components 1 to 7 in Table 36 were heated to approximately 80°C and dissolved (Part A). Components 8 and 9 were placed in a separate container and heated to approximately 80°C and dissolved (Part B). Part B was gradually added to Part A and mixed uniformly to obtain a hair essence. This hair essence had a refreshing feel, was not sticky, and was able to impart softness and smoothness to hair.

[Hair growth agent]
Using the obtained crosslinked polymer particles 1, a hair growth agent having the formulation shown in Table 37 below was prepared.

(Manufacturing method)
A hair growth agent was obtained by uniformly mixing the components shown in Table 37. This hair growth agent was able to prevent hair loss, dandruff, and itching.

[Perm agent]
Using the obtained crosslinked polymer particles 2, perm agents having the formulations shown in Tables 38 and 39 below were prepared.

(Preparation method: 1 liquid)
Component 11 was dissolved in most of component 13 in Table 38, then component 12 was added little by little and dissolved, and then components 8 to 10 were added and dissolved (Part A). The remainder of component 13 was placed in a separate container, and components 6 and 7 were added, heated and dissolved (Part B). Components 1 to 5 were added to another container, heated to about 50°C and dissolved (Part C). Part B was added to Part A and mixed uniformly, and then Part C was gradually added and mixed uniformly to obtain one solution of a perm agent.

(Preparation method: 2 liquids)
Most of component 10 in Table 39 was taken and heated to approximately 60°C. Components 1 to 3 were added and dissolved, and then component 4 was added and dissolved. Components 5 and 6 were then added and heated to dissolve, and while slowly cooling to around 40°C, components 7 to 9 were added and mixed uniformly. The remainder of component 10 was added, mixed uniformly, and cooled to obtain a second solution of the perm agent.

This perm agent was a perm agent that imparted smoothness and softness to hair when applied to the hair.

[Bath additives (bubble bath)]
Using the obtained crosslinked polymer particles 3, a bath agent having the formulation shown in Table 40 below was prepared.

(Manufacturing method)
Each component listed in Table 40 was mixed uniformly for each section to obtain a mixture (Part A and Part B). Part A was dissolved in a portion of Part C and homogenized. The remaining Parts C and B were added to this mixture and kneaded well to obtain a bath agent. This bath agent had the effect of moisturizing the skin and improving its luster.

[Cleansing oil]
Using the obtained crosslinked polymer particles 4, a cleansing oil having the formulation shown in Table 41 below was prepared.

(Preparation method)
A cleansing oil was obtained by heating, dissolving, and mixing all of the ingredients listed in Table 41. This cleansing oil was transparent, viscous, and did not drip during use. It also had a refreshing feel and blended well with foundation, makeup, and other makeup, allowing it to quickly remove these.

[Liquid facial cleanser]
Using the obtained crosslinked polymer particles 5, a liquid facial cleanser having the formulation shown in Table 42 below was prepared.

(Manufacturing method)
Components 3 and 10 in Table 42 were heated to approximately 80°C and dissolved (Part A). Components 1, 2, 4 to 9, and 11 to 13 were added to Part A, heated to approximately 80°C until uniformly dissolved, and then cooled to obtain a liquid facial cleanser. A blank formulation was prepared by omitting only component 9. Ten panelists evaluated the feel of the skin after using the facial cleanser. The evaluation results showed that the product was superior to the blank in both the smooth feeling and moist feeling categories.

[Body shampoo]
Using the obtained crosslinked polymer particles 6, a body shampoo having the formulation shown in Table 43 below was prepared.

(Manufacturing method)
Component 1 and a portion of component 11 in Table 43 were heated to about 80°C and mixed uniformly (Part A). Components 2 to 10 and the remainder of component 11 were heated to about 80°C and mixed uniformly (Part B). Part A was gradually added to Part B while stirring, and mixed uniformly to obtain a body soap. A blank formulation was prepared by omitting only component 8. Ten panelists evaluated the feel of the skin after use of the body shampoo. The results were superior to the blank in both evaluation categories of smoothness and moisturizing feel.

[soap]
Using the obtained crosslinked polymer particles 7, a soap having the formulation shown in Table 44 below was prepared.

(Manufacturing method)
All of the components listed in Table 44 were heated to 80°C to dissolve, cooled with stirring, poured into a mold and allowed to stand, to obtain soap. In addition, an unblended soap was prepared from a recipe that excluded only component 1. The soap containing component 1 (crosslinked polymer particles 7) was found to be superior as a greasing agent, imparting a moist feeling and a smooth, slippery feeling to the skin compared to the unblended soap.

Claims (11)

Crosslinked polymer particles for cosmetics or quasi-drugs,
the crosslinked polymer particles have a content of structural units derived from (meth)acrylic acid (salt) of 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the crosslinked polymer,
the crosslinked polymer particles have a volume average particle diameter D50 of 8 μm or more and 20 μm or less, and a half width of the volume average particle diameter of 3 μm or more and less than 20 μm;
The (meth)acrylic acid (salt) is (meth)acrylic acid or a (meth)acrylic acid salt obtained by neutralizing the (meth)acrylic acid with a basic compound,
the neutralization rate of the (meth)acrylic acid (salt) is 60 mol % to 75 mol %;
the basic compound is at least one selected from the group consisting of alkali metal carbonates, alkali metal hydrogencarbonates, alkali metal hydroxides, ammonia, and organic amines ;
The crosslinked polymer particles for use in cosmetics or quasi-drugs have a water absorption capacity for deionized water of 150 g/g or less without pressure . The crosslinked polymer particles for cosmetics or quasi-drugs according to claim 1 have a turbidity of 50% or less. The crosslinked polymer particles for cosmetics or quasi-drugs according to claim 1 or 2, wherein the crosslinked polymer is crosslinked with a compound having two or more ethylenically unsaturated groups per molecule. A cosmetic or quasi-drug containing the crosslinked polymer particles described in claim 1 or 2. The cosmetic or quasi-drug according to claim 4, which is for use on the skin. The cosmetic or quasi-drug according to claim 4, further comprising an inorganic white pigment. A method for producing crosslinked polymer particles for cosmetics or quasi-drugs, comprising:
the crosslinked polymer is obtained by polymerizing 20 parts by mass or more and 100 parts by mass or less of (meth)acrylic acid (salt) per 100 parts by mass of all monomers,
During the polymerization, a hydrophilic polymer is added in an amount of 5% by mass or less relative to the mass of the total monomers,
the crosslinked polymer particles have a volume average particle size of 8 μm or more and 20 μm or less, and a half width of the volume average particle size of 3 μm or more and less than 20 μm;
the (meth)acrylic acid (salt) is (meth)acrylic acid and/or a (meth)acrylic acid salt obtained by neutralizing the (meth)acrylic acid with a basic compound,
the basic compound is at least one selected from the group consisting of alkali metal carbonates, alkali metal hydrogencarbonates, alkali metal hydroxides, ammonia, and organic amines ;
the crosslinked polymer particles have a water absorption capacity for deionized water under no pressure of 150 g/g or less;
The method for producing crosslinked polymer particles for cosmetics or quasi-drugs comprises pulverizing the crosslinked polymer after the polymerization . The method for producing crosslinked polymer particles for cosmetics or quasi-drugs according to claim 7, wherein the polymerization uses a compound having two or more ethylenically unsaturated groups per molecule. The method for producing crosslinked polymer particles for cosmetics or quasi-drugs according to claim 7 or 8 , wherein the crosslinked polymer is dried between the polymerization and the pulverization. The method for producing crosslinked polymer particles for cosmetics or quasi-drugs according to claim 7 or 8, wherein 50 parts by mass or more and 100 parts by mass or less of (meth)acrylic acid (salt) or 50 parts by mass or more and 80 parts by mass or less of acrylamide are polymerized per 100 parts by mass of all monomers. A method for producing a cosmetic or a quasi-drug, comprising:
A method for producing a cosmetic or quasi-drug, further comprising the step of adding an inorganic white pigment to the crosslinked polymer particles for cosmetic or quasi-drug use according to claim 1 or 2.