JP3539008B2 - Method for producing resin particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to ultraviolet-absorbing resin particles and a method for producing the resin particles. More specifically, the present invention relates to resin particles for protecting the skin by absorbing ultraviolet rays harmful to the skin, for example, by being added to cosmetics, and a method for producing the resin particles.

[0002]

BACKGROUND OF THE INVENTION The sun's rays contain ultraviolet rays that cause erythema (sunburn) on human skin and cause spots, freckles, and the like. Cosmetics containing absorbents have been used.

[0003] Ultraviolet absorbers include inorganic pigments such as titanium dioxide, zinc oxide and iron oxide that block ultraviolet rays, and organic ultraviolet absorbers that absorb ultraviolet rays. The above-mentioned inorganic pigments conceal the skin and shield ultraviolet rays. When such inorganic pigments are applied to the skin, they whiten or color, so that they cannot be incorporated in cosmetics in large amounts.

On the other hand, organic ultraviolet absorbers absorb ultraviolet rays without concealing the skin, so that there is no problem of whitening or coloring. For these reasons, organic UV absorbers have been increasingly used in recent years as UV absorbers.

[0005] However, some organic UV absorbers have irritating properties to the skin. If such organic UV absorbers are used as they are when mixed with other cosmetic base materials, they may irritate the skin. May be undesirable.

In order to prevent such organic UV absorbers from coming into direct contact with the skin, it has been proposed to disperse and restrain the UV absorbers inside resin particles. For example, JP-B-62-51931, JP-A-62
JP-A-198612 discloses resin particles containing such an organic ultraviolet absorber.

[0007] By constraining the organic UV absorber in the resin particles in this manner, the UV absorber becomes less likely to come into direct contact with the skin, and the irritation is reduced as compared with cosmetics containing the UV absorber directly. Therefore, if the resin particles in which the ultraviolet absorbent is constrained as described above are used, the skin irritation caused by the ultraviolet absorbent should be eliminated, but even if such resin particles are actually used, the skin is still still affected by the ultraviolet absorbent. The skin may be irritated.

The present inventor has studied the skin irritation of cosmetics containing such resin particles containing an organic ultraviolet absorber, and as a result, the skin irritation is particularly high when the cosmetic base is an oil. We got the knowledge that there is a tendency.

The above-mentioned resin particles have a spongy porous structure, and the ultraviolet absorbent is uniformly distributed throughout the resin layer of the resin particles having such a structure. That is, such resin particles are produced by emulsion polymerization or suspension polymerization by dispersing a reactive monomer and an ultraviolet absorber in a reaction medium, and polymerize while involving the ultraviolet absorber when the reactive monomer is polymerized. Thereby, the ultraviolet absorber is bound in the resin particles having a spongy porous structure. Therefore, there is almost no concentration gradient of the ultraviolet absorber between the surface of the resin particles and the inside of the resin particles.

However, since such resin particles have a spongy porous structure and the UV absorber has a high lipophilicity, when such resin particles are used as a cosmetic, the surface of the resin particles may be damaged. There has been a problem that the oily cosmetic base material penetrates into the resin particles from the porous portion to elute the ultraviolet absorber, and the eluted ultraviolet absorber irritates the skin.

The present inventor blends an organic ultraviolet absorber in a core material portion, and comprises a (meth) acrylic acid resin and / or a styrene resin containing no organic ultraviolet absorber around the core material portion. Based on the finding that the formation of the surface layer portion can reduce the amount of the organic ultraviolet absorber eluted, the cosmetic particles whose surface layer is coated with such a (meth) acrylic acid resin or styrene resin have already been used. An application has been filed (see Japanese Patent Application No. 6-92613).

Further studies based on such inventions have led to the finding that the formation of the surface layer using a specific resin can further reduce the amount of the organic ultraviolet absorber eluted, and the present invention Was completed.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin particle having a reduced amount of an organic organic ultraviolet absorber eluted without reducing the ultraviolet absorbing effect, and a method for producing the resin particle.

[0014]

SUMMARY OF THE INVENTION The resin particles of the present invention comprise a core portion made of a (meth) acrylic resin and / or a styrene resin containing an organic ultraviolet absorbent, and a surface layer formed on the surface of the core portion. And the surface layer is made of a hydrophilic resin.

The resin particles are obtained by dissolving an organic ultraviolet absorber in a monomer forming a (meth) acrylic resin and / or a styrene resin as a core material, and then adding the organic ultraviolet absorber-containing monomer to an aqueous solution. A polymerization reaction is performed by dispersing the monomer in a medium, and then a monomer that forms a hydrophilic resin in the aqueous medium (the surface of the formed particles is given hydrophilicity).
To form a hydrophobic resin with 10 to 50 parts by weight of the monomer
A monomer that forms a hydrophilic resin on the surface of the polymer particles formed in the above-described step in the aqueous medium, or the particles to be formed. Can impart hydrophilicity to the surface
Can form hydrophobic resin with 10 to 50 parts by weight of monomer
Adding a hydrophilic resin obtained by copolymerizing 90 to 50 parts by weight of a monomer, and attaching the hydrophilic resin to the surface of the polymer particles produced in the above step to form a surface layer portion; Can be manufactured.

The resin particles of the present invention have a structure comprising a core portion and a surface layer formed on the surface of the core portion, and the organic ultraviolet absorber is contained in the core portion. Yes,
It is not substantially contained in the surface layer. Then, by forming the surface layer portion with a hydrophilic resin, the amount of the organic ultraviolet absorbent that elutes through the surface layer portion can be reduced.

The resin particles of the present invention are formed by preliminarily dissolving an organic ultraviolet absorber in a (meth) acrylic monomer and / or a styrene monomer forming a core portion and polymerizing the same. After forming, a monomer that forms a hydrophilic resin ( which can impart hydrophilicity to the surface of the formed particles)
Can form hydrophobic resin with 10 to 50 parts by weight of monomer
A monomer consisting of 90 to 50 parts by weight of a monomer) is separately supplied to the reaction system, and the monomer is polymerized to form a surface layer made of a hydrophilic resin on the surface of the core material, or
Monomer 10 capable of imparting hydrophilicity to the formed particle surface
５０50 parts by weight, and a monomer 90 capable of forming a hydrophobic resin
It can be easily manufactured by adding a hydrophilic resin obtained by copolymerizing with 50 to 50 parts by weight and attaching it to the surface of the core material to form the surface layer portion.

[0018]

Next, the resin particles of the present invention and the method for producing the same will be described in detail. The resin particles of the present invention comprise a core part and a surface part formed on the surface of the core part.

This core portion is made of a (meth) acrylic resin,
It is formed of a styrene-based resin, a mixed resin of a (meth) acrylic-based resin and a styrene-based resin, or a copolymer of a (meth) acrylic-based monomer and a styrene-based monomer. Organic UV absorber is included.

The (meth) acrylic resin forming the core material may be a (co) polymer of (meth) acrylate or a copolymer of (meth) acrylate monomer and another monomer. It is preferred that they are united.

Here, examples of (meth) acrylate-based monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. ) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-propyl (meth) acrylate, chloro
2-hydroxyethyl (meth) acrylate, diethylene glycol mono (meth) acrylate, methoxyethyl (meth) acrylate, glycidyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate and isoboronor (meth) ) Acrylate and the like.

Specific examples of the styrene monomer forming the core of the resin particles of the present invention include styrene,
Alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene and octylstyrene; fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, Mention may be made of halogenated styrenes, such as iodinated styrene and chloromethylstyrene; and nitrostyrene, acetylstyrene and methoxystyrene.

The core material is preferably formed of one of the above-mentioned (meth) acrylic resin and styrene resin alone, but may be formed of a composition comprising these resins. Good. Further, a copolymer of the above (meth) acrylate monomer and a styrene monomer may be used.

Further, the (meth) acrylic resin or the styrene resin is copolymerized with another monomer copolymerizable with the (meth) acrylate ester monomer and / or the styrene monomer. It may be.

Examples of other monomers copolymerizable with the (meth) acrylic ester monomer or the styrene monomer include vinyl monomers and unsaturated carboxylic acid monomers.

Specific examples of the vinyl monomer include vinyl pyridine, vinyl pyrrolidone, vinyl carbazole, vinyl acetate and acrylonitrile; conjugated diene monomers such as butadiene, isoprene and chloroprene; halogens such as vinyl chloride and vinyl bromide. And vinylidene halides such as vinyl chloride and vinylidene chloride.

Specific examples of the unsaturated carboxylic acid monomer include (meth) acrylic acid, α-ethyl (meth) acrylic acid, crotonic acid, α-methyl crotonic acid,
Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as α-ethylcrotonic acid, isocrotonic acid, tiglic acid and ungeric acid; addition of maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid and hydromuconic acid Examples thereof include polymerizable unsaturated aliphatic dicarboxylic acids.

Further, the copolymer of the (meth) acrylic ester may be copolymerized with a bifunctional or polyfunctional monomer, if necessary. Examples of bifunctional or polyfunctional monomers include ethylene glycol di (meth) acrylate, triethylene glycol (meth) acrylate, tetraethylene glycol (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate. ) Acrylates, 1,1,1-trihydroxymethylethane triacrylate, 1,1,1-trishydroxymethylmethylethane triacrylate, 1,1,1-trishydroxymethylpropane triacrylate and vinylbenzene can be mentioned. .

When the core portion is made of a (meth) acrylic resin, a homopolymer of a (meth) acrylic ester monomer is preferable, but not limited thereto. 20 to 100 parts by weight, preferably 40 to 100 parts by weight, a styrenic monomer,
Usually 0 to 80 parts by weight, preferably 0 to 60 parts by weight, 2
A functional or polyfunctional monomer, usually 0 to 20 parts by weight, preferably 0 to 15 parts by weight, a vinyl monomer,
Usually, a copolymer obtained by (co) polymerizing an unsaturated carboxylic acid monomer in an amount of 0 to 50 parts by weight and usually in an amount of 0 to 50 parts by weight has a possibility of being used.

When the core material is made of a styrene resin, a homopolymer of a styrene monomer is preferable.
Not limited to this, the styrene-based monomer is usually used in an amount of 20 to 1
00 parts by weight, preferably 40 to 100 parts by weight, (meth)
The acrylate ester monomer is usually 0 to 80 parts by weight, preferably 0 to 60 parts by weight, and the bifunctional or polyfunctional monomer is usually 0 to 20 parts by weight, preferably 0 to 1 part by weight.
There is a possibility that a copolymer obtained by (co) polymerizing 5 parts by weight of a vinyl monomer in an amount of usually 0 to 50 parts by weight and an unsaturated carboxylic acid monomer in an amount of usually 0 to 50 parts by weight may be used. ing.

When the core is composed of a copolymer of a (meth) acrylate monomer and a styrene monomer, the (meth) acrylate monomer is usually 20 to 80 parts by weight, preferably 20 to 80 parts by weight. 40-60 parts by weight,
It is possible to use a copolymer obtained by copolymerizing a styrene-based monomer in an amount of usually 20 to 80 parts by weight, preferably 40 to 60 parts by weight. The functional monomer is usually used in an amount of 0 to 20.
Parts by weight, preferably 0 to 15 parts by weight, of a vinyl-based monomer, usually 0 to 50 parts by weight, and an unsaturated carboxylic acid monomer usually (co) polymerized in an amount of 0 to 50 parts by weight. Has the potential to be used.

Further, a poly (meth) acrylate polymer obtained by polymerizing a (meth) acrylate monomer alone, or a poly (meth) acrylate polymer obtained by copolymerizing a plurality of types of (meth) acrylate monomers. Acrylate copolymers are particularly preferred, and polystyrene resins obtained by polymerizing styrene monomers alone or polystyrene copolymers obtained by copolymerizing a plurality of types of styrene monomers are particularly preferred. A core made of a resin formed from the above monomer is insoluble in water (that is, lipophilic rather than hydrophilic).

The core material contains an organic UV absorber. In the present invention, as an organic ultraviolet absorber, 4-tert-butyl-4′-methoxy-dibenzoylmethane,
Effectiveness of p-dimethylaminooctyl benzoate, p-methoxycinnamic acid ester of glycerin as shown by the following formula, 2-hydroxy-4-methoxybenzophenone and 2 (2'-hydroxy-5-methylphenyl) benzotriazole Especially high.

[0034]

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Here, 4-tert-butyl-4'-methoxy-dibenzoylmethane has a high ability to absorb ultraviolet light having an A wavelength of 320 to 400 nm, and octyl p-dimethylaminobenzoate, glycerin represented by the above formula P-methoxycinnamate, 2-hydroxy-4-methoxybenzophenone, has a high ability to absorb ultraviolet light having a B wavelength of 280 to 320 nm, and 2 (2'-hydroxy-5-methylphenyl) benzotriazole has It has a high ability to absorb ultraviolet light over both A and B wavelengths.

In the present invention, the above-mentioned organic ultraviolet absorbers can be used alone or in combination of two or more. Further, in the present invention, in addition to the above-mentioned ultraviolet absorber, aminobenzoate ultraviolet absorber, salicylate ultraviolet absorber, benzophenone ultraviolet absorber, benzotriazole ultraviolet absorber, cinnamate ultraviolet absorber, nickel Use other UV absorbers such as chelate UV absorbers, hindered amine UV absorbers, urocanic acid UV absorbers and vitamin UV absorbers alone or in combination with the above three organic UV absorbers You can also. In addition, these UV absorbers
It can be used alone or in combination with the above-mentioned ultraviolet absorber. In particular, in the present invention, it is preferable to use a UV absorber that is soluble in the monomer used to produce the resin forming the core part, and in particular, an aminobenzoate UV absorber, a salicylate UV absorber, and a cinnamate UV absorber UV absorbers, benzophenone UV absorbers, urocanic acid UV absorbers, and vitamin UV absorbers are preferred.

Examples of the aminobenzoate-based ultraviolet absorber used herein include 2-ethylhexyl-p-dimethylaminobenzoate, amyl-p-dimethylaminobenzoate, glyceryl-p-aminobenzoate, and ethyl-p-dimethyl. Mention may be made of aminobenzoate, ethyl-p-diethylaminobenzoate and glyceryl-mono-p-aminobenzoate.

Examples of salicylate-based ultraviolet absorbers include p-tert-butyl salicylate, p-octylphenyl salicylate and dipropylene glycol salicylate.

Examples of the cinnamate-based ultraviolet absorber include 2-ethoxyethyl-p-methoxycinnamate, 2,2'-
Bis- (p-methoxystyryl) -ethyl-p-methoxycinnamate, 2-ethoxyethyl-p-methoxycinnamate and methyl-2,5-diisopropylcinnamate can be mentioned.

Examples of the benzophenone type ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, sodium
-2,2'-hydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone,
2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone and 2,2'-dihydroxy-4,4'-
Dimethoxybenzophenone can be mentioned.

Examples of the urocanic acid-based ultraviolet absorber include urocanic acid and ethyl urocanate. Furthermore, examples of vitamin UV absorbers include vitamin A ₁ , vitamin A ₂ , vitamin A ₃ , vitamin B ₂ and vitamin B ₁₂ .

The above-mentioned organic ultraviolet absorber is usually added to the core part in an amount of 1 to 100 parts by weight of the resin forming the core part.
It is contained in an amount of up to 40 parts by weight, preferably 10 to 30 parts by weight.

The core material usually has a thickness of 0.05 to 15 μm.
m, preferably polymer particles having an average particle size of 0.05 to 6 μm. In the resin particles of the present invention, a surface layer portion made of a resin having hydrophilicity is formed on the surface of the core material portion containing the ultraviolet absorbent as described above.

In the present invention, a hydrophilic resin is defined as a coating resin that can be operated as described below so that the sieving residue of the coated PMMA particles is less than 0.5% by weight. That is, when the powder coated with the hydrophobic resin and the powder coated with the hydrophilic resin are compared, the dispersibility of both in water is remarkably different, and the powder coated with the hydrophilic resin is uniform in water. In contrast, powder coated with a hydrophobic resin has low wettability with water, making it difficult to uniformly disperse it in water. I do. Therefore, the hydrophilic resin can be defined by quantifying the difference between the two behaviors with respect to water.

A test for specifying the hydrophilic resin in the present invention is performed as described below. First, methyl methacrylate (MMA) and methacrylic acid (MA)
A) with sample A = 50: 50, sample B = 80: 20, sample C = 90: 10, sample D
= 95: 5, sample E = 100: 0 in an aqueous medium to produce particles having an average particle size of 1 μm.
Here, MMA is a monomer used to form a hydrophobic resin, and MAA is a monomer used to impart hydrophilicity to the particle surface.

A dispersant or the like is adhered to the surface of the particles thus produced.
25 parts by weight of these particles are ultrasonically dispersed in 75 parts by weight of purified water, and a dispersant or the like adhering to the above particles is reduced using a Nutsche or cross-flow filtration device.

The amount of the dispersant is reduced so that the amount of the residual dispersant calculated according to the following equation is 0.001% by weight or less.

[0048]

(Equation 1)

In the above equation, V ₀ is the initial charge (liter), X is nV / 100, C ₀ is the initial dispersant concentration, C∞ is the dispersant concentration during washing, V is the amount of wash water and C is the final dispersant concentration.

Based on the above formula, for example, particles containing a dispersant in an amount of 1% by weight were nV = 25, V / V ₀ = 8 (number of times)
When the washing is performed under the conditions described above, the content of the dispersant calculated from the above formula becomes 0.0002% by weight, and the influence of the dispersant can be neglected.

The test particles are prepared as described above, and the openings are 36 μm (corresponding to 400 mesh).
, A drier that can be heated to 70 ° C., a desiccator large enough to accommodate the sieve, and an electronic balance are prepared.

10 g of the particles from which the dispersant has been removed in advance and 70 g of purified water are mixed, and the particles are dispersed in purified water by applying ultrasonic waves. The sieve weighed in advance is wetted with methanol, and the dispersion in which the particles are dispersed is sieved using a sieve wetted with methanol.

The particles adhering in or around the sieve are poured with water and these particles are also sieved. The particles that cannot be permeated through the sieve by the above operation are giant particles or aggregated particles.

The sieve was placed in a drier heated to 70 ° C. for 1 hour and dried, and then dried in a desiccator for at least 30 hours.
Store for a minute and cool to room temperature. The thus cooled sieve is accurately weighed, and the weight of the initially weighed sieve itself is subtracted from this value to determine the weight of the particles remaining in the sieve.

From the amount of residual particles determined as described above and the weight of the sample (20 g) used in this test,
Determine the weight ratio of the residual particles. The sieve residue obtained as described above is shown in the table below.

[0056]

[Table 1]

Based on the values shown in Table 1, the hydrophilic resin in the present invention is defined as a resin having a sieve residue of 0.5% by weight or less. Examples of the functional group introduced into such a hydrophilic resin are shown below.

(1) -COOX (where X is -H, -K, -Na, = Ca _1/2 , ≡Al
_1/3, is either = Mg _1/2 or -NH _4. ), (2) —OH, (3) —NH ₂ or —N (R) ₃ ⁺ X ⁻ (where X is any of —H, —Cl or —Br, and R is each independently hydrogen. represents an atom or a hydrocarbon _{group.), (4) -SO 3} X ( where X is, -H, is either -Na or _{-NH 4.), (5)} -OSO 3 X ( in the formula X is -H, is either -Na or _{-NH 4.), (6)} -O-R-H ( wherein R is a group derived from an alkylene oxide such as ethylene oxide and propylene oxide , and the specifically _{- [CH 2 CH 2 0]} n -, - [CH 2
CH ₂ CH ₂ 0] _n- (n is an arbitrary integer). ).

In the present invention, the above-mentioned functional groups may be independently introduced into the hydrophilic resin, or a plurality of types of functional groups may be introduced. Representative examples of the hydrophilic resin having the above functional group are shown below.

A resin comprising methyl methacrylate (MMA) and acrylic acid (AA). A resin having the following structure obtained by copolymerizing MMA = 90 to 50 parts by weight and AA = 10 to 50 parts by weight.

[0061]

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In the above formula, a: b = 60 mol: 40
Is a mole. In the above formula, p + m + n is 3
１1200. Further, the weight average molecular weight of this resin is 1,000 to 400,000.

A resin comprising methyl methacrylate (MMA) and methacrylic acid (MAA). A resin having the following structure by copolymerizing MMA = 90 to 50 parts by weight and MAA = 10 to 50 parts by weight:

[0064]

Embedded image

In the above formula, a: b = 70-90 mol: 30-30-10 mol. In the above equation, p
+ M + n is 3-1200. Further, the weight average molecular weight of this resin is 1,000 to 400,000.

A copolymer of methyl methacrylate (MMA) and 2-hydroxyethyl acrylate (HEA). A resin having the following structure obtained by copolymerizing MMA = 90 to 50 parts by weight and HEA = 10 to 50 parts by weight:

[0067]

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In the above formula, a: b = 70-90 mol: 30-30-10 mol, and p + m + n is 3-120
0. Furthermore, the weight average molecular weight of this resin is usually 1
000 to 400,000.

A copolymer of methyl methacrylate (MMA) and acrylamide (AM). A resin having the following structure obtained by copolymerizing MMA = 90 to 50 parts by weight and AM = 10 to 50 parts by weight:

[0070]

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In the above formula, m is 6 to 2400 and n is 7 to 2200. The resin has a weight average molecular weight of 1,000 to 400,000. Among the hydrophilic resins having a functional group as described above, a resin having a carboxyl group represented by (1) is particularly preferable.

The weight average molecular weight of the above-mentioned hydrophilic resin is usually in the range of 1,000 to 800,000, preferably in the range of 5,000 to 400,000. When the characteristics of the resin are made hydrophilic by introducing a functional group as described above, among the introduced functional groups, there are an acidic group and a basic group. When is introduced, it can be used after neutralization. In particular, when the resin particles of the present invention are used by being blended in a cosmetic, by neutralizing so that the pH value of the aqueous medium in which the resin particles of the present invention are dispersed is about 6 to 9,
It is possible to reduce irritation to the skin when the resin particles of the present invention are incorporated into a cosmetic.

The surface layer made of such a hydrophilic resin is
Usually it has an average layer thickness of 0.01 to 5 μm, preferably 0.02 to 2 μm. If the average layer thickness of the surface layer part is out of the above range and is thin, the elution of the ultraviolet absorbent from the core material may not be effectively prevented. Often.

The average particle size of the resin particles of the present invention having such a layer structure is usually in the range of 0.06 to 20 μm, preferably 0.07 to 8 μm. In the resin particles of the present invention, the organic UV absorber is contained in the core material portion, and the surface of the particles that come into contact with the component that elutes the organic UV absorber such as an oil base material has an affinity for such an oil base material. Since it is made of a hydrophilic resin having no organic resin, the hydrophilic resin does not substantially contain an organic ultraviolet absorber. Further, the ultraviolet absorber contained in the core portion of the resin particles of the present invention is usually oily, and often does not show affinity for the hydrophilic resin forming the surface layer portion,
Therefore, it is extremely difficult for the organic ultraviolet absorber contained in the core material to elute through the surface layer made of the hydrophilic resin.

The resin particles of the present invention are obtained by forming a core material containing an organic ultraviolet absorbent in an aqueous medium, and then adding a monomer capable of forming a hydrophilic resin to the aqueous medium. It can be produced by a method of polymerizing at the outer periphery (first method) or a method of forming a core material and then adding a hydrophilic resin to adhere to the outer periphery of the core material (second method).

The first method is to dissolve an organic ultraviolet absorber in a monomer forming a (meth) acrylic resin, and then disperse the organic ultraviolet absorber-containing monomer in fine particles in an aqueous medium for polymerization. Then, the obtained particles are further polymerized with a monomer for forming a (meth) acrylic resin.

In the method of the present invention, first, an organic ultraviolet absorber is blended with a monomer for forming the core portion, and the organic ultraviolet absorber is dissolved in the monomer. Next, the monomer in which the organic ultraviolet absorber is dissolved is dispersed in an aqueous medium. Here, water is usually used as the aqueous medium, but the aqueous medium may be mixed with a water-soluble organic solvent such as alcohol.

In dispersing the above-mentioned monomer in which the organic ultraviolet absorbent is dissolved in an aqueous medium, an emulsifier, a dispersion stabilizer and the like can be used. Therefore, the core portion can be formed by emulsion polymerization, soap-free emulsion polymerization, suspension polymerization, or seed polymerization. Examples of emulsifiers used in the case of emulsion polymerization include, for example, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; polyethylene glycol alkyl ethers such as polyethylene glycol nonylphenyl ether; and vinyl, acryloyl and allyl. Examples include a reactive emulsifier having a reactive group such as a group, and examples of the dispersion stabilizer include water-soluble polymer compounds such as polyvinyl alcohol and polyacrylate. The emulsifier and the dispersion stabilizer are usually used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the monomer.

The monomer in which the organic ultraviolet absorber is dissolved is usually dispersed in an aqueous medium using a dispersing device such as a homomixer. Further, in this aqueous medium, the reaction initiator is usually dispersed and polymerized. Examples of the reaction initiator that can be used here include azo compounds such as azobisisobutyronitrile, organic peroxides such as benzoyl peroxide and lauryl peroxide, and persulfates such as potassium persulfate and ammonium persulfate. Salts may be mentioned. Such initiators are usually used in amounts of 0.1 to 5 parts by weight per 100 parts by weight of monomer.

When polymerizing the monomer dispersed in the aqueous medium as described above, it is preferable to purge the inside of the reaction vessel with an inert gas such as nitrogen gas. After purging the inside of the reaction vessel with the inert gas, the polymerization reaction proceeds by heating the temperature of the reaction solution to 60 to 80 ° C. Then, as the monomer is polymerized, the organic ultraviolet absorbent dissolved in the monomer precipitates and is sealed in the core material portion by the resin forming the core material portion. When the ultraviolet absorbent is dissolved in the monomer in advance and then polymerized, the concentration of the organic ultraviolet absorbent in the surface portion of the resin particles generated by the polymerization tends to be lower than that in the central portion.

Under the above reaction conditions, the reaction time required to produce the polymer particles forming the core is usually 3 to 6 hours. A monomer forming a hydrophilic resin is added to a reaction solution containing particles (core material) containing an organic ultraviolet absorber formed in this manner,
The surface layer can be formed by copolymerizing this monomer and precipitating it around the core particles.

Specifically, in the reaction solution in which the polymer particles forming the core portion are dispersed as described above, the monomer forming the hydrophilic resin is mixed with the monomer used to form the core portion. 10 to 200 parts by weight is added to 100 parts by weight, and the mixture is stirred with a stirring device such as a homomixer. Usually, a reaction initiator is further added to the aqueous medium.

It is considered that the monomer thus added at least partially adheres to the surface of the polymer particles produced in the above step. After the addition of the monomer, the reaction solution is heated to 60 to 80 ° C. to polymerize the monomer on the surface of the polymer particles to form a surface layer. The reaction time for forming the surface layer is usually 3 to 6 hours.

Since the organic UV absorber is not dissolved in the hydrophilic resin forming the surface layer thus formed, the surface layer does not substantially contain the organic UV absorber. After forming the surface layer as described above, if necessary, particles generated by filtration or centrifugation are separated.

If necessary, the obtained resin particles are washed and used. In the second method of the present invention, instead of the monomer used in the first method, a hydrophilic resin obtained by polymerizing such a monomer is separately manufactured, and this hydrophilic resin is directly used in a reaction solution. To make the hydrophilic resin adhere to the surface of the polymer particles as the core material.

The amount of the hydrophilic resin used here is usually from 1 to 3 per 100 parts by weight of the polymer particles as the core material.
0 parts by weight, preferably about 3 to 10 parts by weight. At least a part of the hydrophilic resin thus mixed adheres to the surface of the polymer particles as the core material to form a surface layer.

The resin particles thus produced can be provided as a dispersion in an aqueous medium, or can be further separated from the aqueous medium, dried, and then crushed to provide a powder. it can.

In the present invention, when producing the resin particles as described above, the polymerization reaction of the monomer can be carried out in the presence of a pigment, for example, an extender or a pearl pigment. When the polymerization is carried out in the presence of the constitutional content, a composite in which the surface of the pigment is coated with the resin particles of the present invention can be obtained.

In this method, for example, when the production method of the present invention is carried out in the coexistence of an extender or a pearl pigment, the amount of the resin particles of the present invention generated per 100 parts by weight of the extender or the pearl pigment is 110 Parts by weight or less, preferably 100 parts by weight or less, more preferably 98 to 5 parts by weight
By adjusting the amount of the monomer so as to be within the range of parts by weight, the surface of the extender or the pearl pigment can be coated with the resin particles of the present invention. The extender pigment or pearl pigment whose surface is coated with the resin particles of the present invention has improved properties such as fluidity and glossiness of the extender pigment depending on the amount of the resin particles coated.

In the resin particles of the present invention, since the surface layer is formed on the outer periphery of the core containing the organic ultraviolet absorbent, the organic ultraviolet absorbent can be sealed in the core. Therefore, even if the resin particles are used together with an oil material capable of dissolving an organic ultraviolet absorber such as an ester oil, the organic ultraviolet absorber mainly contained in the core of the resin particles of the present invention. Does not penetrate into the surface layer portion made of the hydrophilic resin, and the amount of the organic ultraviolet absorbent eluted from the surface of the resin particles of the present invention is extremely small.

The resin particles of the present invention can be blended in cosmetics as an ultraviolet ray inhibitor, and the surface of the resin particles is coated with a hydrophilic resin. Thereby, ultraviolet rays can be blocked and cosmetics can be given a wet feeling.

The resin particles of the present invention comprise a core material containing an organic ultraviolet absorbent and a surface layer made of a hydrophilic resin formed on the outer periphery of the core. The organic ultraviolet absorbent is as described above. An organic UV inhibitor is an essential component, but as the UV absorber, an inorganic UV shielding agent such as titanium dioxide, iron oxide, zinc oxide, barium sulfate, etc. is used in combination with the above organic UV ultraviolet absorber. You may. Such an inorganic ultraviolet shielding agent is insoluble in the monomer that forms the core portion, but can be stably retained in the core portion by finely dispersing it in the monomer.

The resin particles of the present invention can be used as they are with other cosmetic raw materials as they are, or can be used for treating other cosmetic raw materials, for example, by coating other cosmetic raw materials such as extender pigments as described above. And can be used with other cosmetic ingredients thus treated.

[0094]

The resin particles of the present invention have a structure comprising a core portion and a surface layer portion, and the resin particles further comprise a highly transparent (meth) acrylic resin and / or styrene resin. Is formed from. In the resin particles, the organic ultraviolet absorbent is contained in the core material portion, and the surface layer portion contains substantially no organic ultraviolet absorbent. Moreover, since the surface layer is formed of a hydrophilic resin, and the ultraviolet absorber contained in the core material is organic and does not exhibit hydrophilicity, the organic ultraviolet absorber penetrates into the surface layer. Hateful.

Accordingly, it is possible to reduce the irritation caused by the eluted organic ultraviolet absorber, for example, the irritation caused by the elution of the organic ultraviolet absorber when the resin particles of the present invention are used in cosmetics. it can.

Further, the surface layer constituting the resin particles of the present invention is formed of a hydrophilic resin, and since this layer itself has a water retention property, by using the resin particles of the present invention for cosmetics, The water retention of the water is improved.

The cosmetic containing the cosmetic particles of the present invention uses a highly transparent (meth) acrylic resin or styrene resin so that ultraviolet rays are reliably absorbed by the core of the particles. Therefore, it has an ultraviolet absorbing effect equivalent to that of a cosmetic containing the same amount of an organic ultraviolet absorbing agent.

The cosmetic particles of the present invention contain an organic ultraviolet absorber dissolved in a (meth) acrylic monomer or a styrene monomer in advance, and then contain the organic ultraviolet absorber (meth). By dispersing and polymerizing an acrylic monomer or a styrene monomer in an aqueous medium, first, a core portion containing an organic ultraviolet absorber is formed, and then a monomer capable of forming a hydrophilic resin in the aqueous medium is formed. It can be easily formed by blending and polymerizing at least a part of these monomers on the surface of the core material, or by blending a hydrophilic resin and attaching it to the surface of the core material.

[0099]

EXAMPLES Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited to these examples.

[0100]

Example 1 90 g of methyl methacrylate (MMA)
After completely dissolving 10 g of 4-tert-butyl-4'-methoxydibenzoylmethane (organic ultraviolet absorber), 1 g of azobisisobutyronitrile (AIBN) was further added and dissolved.

Separately, 500 ml of purified water was placed in a round-bottom separable flask, and 1 g of sodium dodecylbenzenesulfonate as an emulsifier was added thereto, and the mixture was sufficiently mixed and dispersed using a homomixer.

To purified water in which the emulsifier was dispersed as described above, MMA in which the organic ultraviolet absorbent obtained in the above step was dissolved was added and emulsified by a homomixer. After the emulsification, the emulsion in the flask was sealed with nitrogen gas for 30 minutes, and then a polymerization reaction was performed for 5 hours while stirring at a temperature of 73 ° C. After 5 hours, the reaction was cooled to room temperature.

The average particle size of the obtained particles was 0.8 μm. Next, 30 g of MMA, 30 g of acrylic acid and azobisisobutyronitrile (AIBN) 1 were added to the reaction solution.
g, and the mixture was sufficiently stirred.
The mixture was heated to 3 ° C. and reacted for 5 hours.

After a lapse of 5 hours, NaOH was added to the reaction solution to adjust the pH value of the reaction solution to 7, followed by cooling to room temperature. Next, the generated particles and the reaction solution were separated by filtration.

The average particle size of the obtained particles is 0.90 μm.
The particles have an average thickness of 0.1 on the surface of the core material.
A surface layer made of a hydrophilic resin having a thickness of 0 μm is formed, and this surface layer contains substantially no organic ultraviolet absorber.

One part by weight of the obtained particles was dispersed in 999 parts by weight of an ester oil in which the organic ultraviolet absorbent was soluble and the polyacrylate resin was insoluble by applying ultrasonic waves for 3 minutes. After allowing to stand for 24 hours, the supernatant was separated and the particles contained therein were separated by centrifugation at 2000 rpm for 20 minutes. The absorbance of the obtained oil is measured, the amount of the eluted organic ultraviolet absorber is determined from a calibration curve prepared in advance, and the amount of the eluted organic ultraviolet absorber is used.
It was expressed as a relative value to

Table 2 shows the results.

[0108]

Example 2 Particles were produced in the same manner as in Example 1, except that 30 g of methacrylic acid was used instead of 30 g of acrylic acid.

The average particle size of the obtained particles is 0.90 μm.
m. In these particles, a surface layer made of a hydrophilic resin having an average thickness of 0.10 μm is formed on the surface of the core portion, and the surface layer substantially contains an organic ultraviolet absorber. Absent.

[0110] The particles obtained in the manner described in Example 1 were used.
The dissolution test of the organic ultraviolet absorbent was carried out in the same manner as described above.
Table 2 shows the results.

[0111]

Example 3 Particles were produced in the same manner as in Example 1, except that 30 g of acrylic acid was used instead of 30 g of acrylic acid.

The average particle size of the obtained particles is 0.90 μm.
m. In these particles, a surface layer made of a hydrophilic resin having an average thickness of 0.10 μm is formed on the surface of the core portion, and the surface layer substantially contains an organic ultraviolet absorber. Absent.

[0113] The particles thus obtained were prepared in Example 1
The dissolution test of the organic ultraviolet absorbent was carried out in the same manner as described above.
Table 2 shows the results.

[0114]

[Reference Example 1] To 80 g of methyl methacrylate (MMA)
After completely dissolving 10 g of 4-tert-butyl-4'-methoxydibenzoylmethane (organic ultraviolet absorber), 1 g of azobisisobutyronitrile (AIBN) was added and dissolved.

Separately, 500 ml of purified water was placed in a round-bottom separable flask, and 1 g of sodium dodecylbenzenesulfonate as an emulsifier was added thereto and sufficiently mixed and dispersed using a homomixer.

To purified water in which the emulsifier was dispersed as described above, MMA in which the organic ultraviolet absorber obtained in the above step was dissolved was added and emulsified by a homomixer. After the emulsification, the emulsion in the flask was sealed with nitrogen gas for 30 minutes, and then a polymerization reaction was performed for 2 hours while stirring at a temperature of 73 ° C.

This reaction solution was heated to 80.degree. This 80
10 g of polyacrylic acid as a hydrophilic resin
(Weight in terms of solid content) was added, and the reaction solution was stirred at 80 ° C. for 2 hours.

After 2 hours, the pH of the reaction solution was adjusted to 7 by adding NaOH to the reaction solution, and the solution was cooled to room temperature. The produced particles and the reaction solution were separated by filtration.

The average particle size of the obtained particles is 0.60 μm.
The particles have an average thickness of 0.0 on the surface of the core material.
A surface layer made of polyacrylic acid (partially neutralized) as a hydrophilic resin having a thickness of 2 μm is formed, and this surface layer does not contain an organic ultraviolet absorber.

[0120] The particles obtained in the manner described in Example 1 were used.
The dissolution test of the organic ultraviolet absorbent was carried out in the same manner as described above.
Table 2 shows the results.

[0121]

Comparative Example 1 Particles were prepared in the same manner as in Example 1 except that the operation of forming the surface layer using a hydrophilic resin was not performed, and the operation of adjusting the pH value of the reaction solution with an aqueous NaOH solution was not performed. Manufactured.

The average particle size of the obtained particles was 0.50 μm.
m. No surface layer made of a hydrophilic resin is formed on these particles. The dissolution test of the organic ultraviolet absorber was performed on the particles thus obtained in the same manner as in Example 1.

Table 2 shows the results.

[0124]

[Table 2]

As is clear from Table 2 above, the particles of the present invention are covered with the hydrophilic resin, so that the ultraviolet absorbent is hardly eluted from the resin particles.

[0126]

Reference Example 2 The particles produced in Examples 1 to 3 and Reference Example 1 were added in an amount of 10% by weight based on the total amount of the foundation.
It was subjected to an irritant blended in an amount of, but rough like that might be due to the UV absorber does not occur, and had a good sunscreen performance.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08F 257/02 C08F 265/06 C08J 7/04

Claims (4)

(57) [Claims] 1. An organic ultraviolet absorbent is dissolved in a monomer forming a (meth) acrylic resin and / or a styrene resin as a core material, and then the organic ultraviolet absorbent-containing monomer is dispersed in an aqueous medium. To form a hydrophilic resin in the aqueous medium (a monomer 1 capable of imparting hydrophilicity to the surface of the formed particles).
0 to 50 parts by weight and a monomer 9 capable of forming a hydrophobic resin
It was added to the monomer) consisting of 0-50 parts by weight, or polymerizing monomers to form a hydrophilic resin on the surface of the polymer particles produced in the above Step in the aqueous medium, or the particle surface formed Monomer 10 capable of imparting hydrophilicity
５０50 parts by weight, and a monomer 90 capable of forming a hydrophobic resin
Resin particles obtained by adding a hydrophilic resin obtained by copolymerization of the polymer particles with 50 to 50 parts by weight and attaching the hydrophilic resin to the surface of the polymer particles produced in the above step to form a surface layer portion. Manufacturing method. 2. The method according to claim 1, wherein the hydrophilic resin comprises at least one of the following:
The method for producing resin particles according to claim 1, wherein the resin has a functional group selected from the group consisting of (1) to (6); (1) -COOX (where X is- H, -K, -Na, = Ca1 _{/ 2} , ≡Al
_1/3, is either = Mg _1/2 or -NH _4. ), (2) —OH, (3) —NH ₂ or —N (R) ₃ ⁺ X ⁻ (where X is any of —H, —Cl or —Br, and R is each independently hydrogen. represents an atom or a hydrocarbon _{group.), (4) -SO 3} X ( where X is, -H, is either -Na or _{-NH 4.), (5)} -OSO 3 X ( in the formula X is -H, is either -Na or _{-NH 4.), (6)} -O-R-H ( wherein R is a group derived from an alkylene oxide.). 3. The method according to claim 1, wherein the hydrophilic resin comprises : (a) acrylic acid;
Any one of monomers 10 selected from methacrylic acid, 2-hydroxyethyl acrylate, and acrylamide
To 50 parts by weight, and (b) methyl methacrylate 90 to 5
The method for producing resin particles according to claim 1 or 2, wherein the resin is a resin obtained by copolymerizing 0 parts by weight. 4. The method for producing resin particles according to claim 1, wherein said resin particles are blended into a cosmetic.