JPH11140139A - Spherical fine particle of polymer having wrinkle structure on its surface and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spherical fine particle of polymer, with an average particle diameter of 2 to 300 μm, having a regular wrinkle structure on its surface. SOLUTION: A styrene elastomer is dissolved in an amt. of 5 to 30 pts.wt. in a mixture of 40 to 90 pts.wt. hydrophobic polymerizable vinyl monomer with 1 to 40 pts.wt. crosslinkable monomer, followed by suspension polymn. in an aq. medium to prepare a spherical fine particle of a polymer having a regular wrinkle structure on its surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to polymer fine particles having a wrinkled structure on the surface of the particles. These polymer microparticles are effective for adding to paints and cosmetics to give them viscous properties, light scattering properties and unique surface properties.

[0002]

2. Description of the Related Art Polymer fine particles having an average particle diameter of 2 to 300 μm are usually prepared by forcibly dispersing a polymerizable vinyl monomer in an aqueous medium in the presence of a dispersion stabilizer using a homomixer or the like to form droplets. It is manufactured by having In the production of polymer fine particles by suspension polymerization,
The liquid polymerizable vinyl monomer is usually spherical due to its surface tension in an aqueous medium, and the polymer fine particles obtained by polymerization are also spherical fine particles having a smooth surface. As a method for producing irregularly shaped polymer particles that are not spherical or whose surface is not smooth, a hydrophilic vinyl monomer is used as a polymerizable vinyl monomer, and a crosslinkable monomer is subjected to suspension polymerization in the presence of an oil-soluble substance to form a bowl-shaped polymer fine particle. (JP-A-61-87734 and JP-A-2-255704) are known.
However, spherical polymer fine particles having a regular wrinkle-like structure on the particle surface have not yet been known.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide novel polymer fine particles having a regular wrinkle-like structure on the surface of the polymer fine particles.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to obtain the above polymer fine particles, and as a result, dissolved a styrene elastomer in a mixture of a hydrophobic polymerizable vinyl monomer and a crosslinkable monomer, It has been found that when suspension polymerization is carried out in a medium, novel spherical polymer fine particles having a fine wrinkle-like structure on the surface of the fine particles can be obtained, thereby completing the present invention. That is, the present invention provides (1) spherical polymer fine particles having a regular wrinkle-like structure on the surface, (2) the spherical polymer fine particles according to the above (1) having an average particle diameter of 2 to 300 μm, and (3) hydrophobicity. A styrene-based elastomer is dissolved in a mixture of 40 to 90 parts by weight of a polymerizable vinyl monomer and 1 to 40 parts by weight of a crosslinkable monomer, and the suspension is subjected to suspension polymerization in an aqueous medium. And (4) the method wherein the polymerizable vinyl monomer is an alkyl (meth) acrylate.
The production method described.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrophobic polymerizable vinyl monomer used in the present invention includes, for example, aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene;
Alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, etc .; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate; vinyl ester such as vinyl acetate and vinyl propionate Monomer, vinyl cyanide monomer such as (meth) acrylonitrile, vinyl chloride,
A hydrophobic vinyl monomer having no hydrophilic group such as a hydroxyl group, a carboxyl group, an amino group, or a sulfonic acid group in a molecule such as a halogenated vinyl monomer such as vinylidene chloride can be used. Examples of the crosslinkable vinyl monomer used in the present invention include aromatic divinyl compounds such as divinylbenzene and divinyltoluene; glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate and diethylene glycol di (meth) acrylate; Examples thereof include compounds having two or more polymerizable unsaturated bonds in one molecule such as tri (meth) acrylate such as methylolpropane tri (meth) acrylate and pentaerythritol tetra (meth) acrylate, and tetra (meth) acrylate.

The styrenic elastomer used in the present invention must be soluble in a mixture of a hydrophobic polymerizable vinyl monomer and a crosslinkable monomer at room temperature or under heating. Examples include styrene and butadiene,
And copolymer elastomers such as isoprene. Among them, styrene-butadiene-styrene, styrene-isoprene-styrene, styrene- (ethylene /
Particularly preferred are block copolymer elastomers such as butylene) -styrene and styrene- (ethylene / propylene) -styrene. The molecular weight of these styrene-based elastomers is not particularly limited as long as they can be dissolved in a mixed solution of a hydrophobic polymerizable vinyl monomer at room temperature or by heating, but the viscosity of a toluene solution having a polymer concentration of 25% is 1000 mPa · s.
The viscosity of a toluene solution having a polymer concentration of 15% is 5
It is preferably up to 000 mPa · s. These styrene elastomers can be used alone or in combination of two or more. The amount of each of the hydrophobic polymerizable vinyl monomer, crosslinkable monomer and styrene-based elastomer used is usually 40 to 90: 1 to 40: 5 to 3 by weight.
0, preferably 45 to 80: 3 to 30:10 to 25. If the amount of the hydrophobic polymerizable vinyl monomer, cross-linkable monomer or styrene-based elastomer is out of the above range, spherical polymer fine particles having a sufficient and regular wrinkle structure on the particle surface cannot be obtained.

[0007] In order to increase the solubility of the styrenic elastomer in the mixture of the hydrophobic polymerizable vinyl monomer and the crosslinkable monomer, and to promote the phase separation in the droplets occurring during the polymerization, the styrene-based elastomer must be compatible with the monomer mixture if necessary. An oil-soluble solvent, a low crystalline elastomer such as polybutene, polybutadiene, polyisoprene, or a liquid rubber may be used in combination. Examples of the oil-soluble solvent include esters such as methyl acetate, ethyl acetate, butyl butyrate, and isoamyl butyrate; ketones such as diethyl ketone and methyl ethyl ketone; and aromatic hydrocarbons such as benzene, toluene, and xylene: butane and pentane. And hydrocarbons such as hexane: long-chain alkyl derivatives such as olive oil, rat oil, coconut oil and castor oil. These oil-soluble solvents, low-crystalline elastomers and liquid rubbers are used in an amount of about 5 to 20 parts by weight based on 100 parts by weight of the monomer mixture. The dispersion obtained by dispersing a solution in which each of the monomers and the styrene-based elastomer used in the present invention are dissolved into an aqueous medium is subjected to suspension polymerization in the next step, but the dispersibility of the raw material droplets and the produced polymer particles is improved. Therefore, an appropriate amount of a dispersion stabilizer such as various surfactants and polymer protective colloids is used.

Examples of the dispersion stabilizer include surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, water-soluble polymers such as gelatin, methylcellulose, hydroxyethylcellulose, polyvinyl alcohol and polyacrylate, tricalcium phosphate, and the like. A poorly water-soluble inorganic substance such as magnesium carbonate is used. These dispersion stabilizers can be used alone or in combination of two or more. These dispersion stabilizers can stably carry out the polymerization in the amounts used during normal suspension polymerization. In the suspension polymerization of the present invention, an appropriate amount of a chain transfer agent, a polymerization inhibitor, or the like may be used, if necessary, in addition to the weight initiator. As the polymerization initiator, those usually used in this type of reaction, for example, peroxide initiators such as benzoyl peroxide and lauroyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-iso An azo polymerization initiator such as valeronitrile is exemplified. These polymerization initiators are used after being dissolved in a polymerizable monomer. Chain transfer agents may also be those commonly used in this type of reaction, such as monothiol, polythiol, xanthogen disulfide, thiuram disulfide, mercaptoacetic acid 2-ethylhexyl ester,
Octanoic acid 2-mercaptoethyl ester, mercaptoacetic acid methoxybutyl ester, mercaptopropionic acid methoxybutyl ester, α-methylstyrene dimer, terpinolene and the like are preferably used. As the polymerization inhibitor, an appropriate amount of a commonly used polymerization inhibitor such as sodium nitrite, sodium sulfite, cupric chloride or the like is used.

The average particle size of the polymer fine particles is approximately the same as the dispersion-stabilized droplet diameter of a mixed solution of a hydrophobic polymerizable vinyl monomer, a crosslinkable monomer, and a styrene-based elastomer. Obtained by reaction. The size of the droplet diameter can be arbitrarily controlled by selecting the type and amount of the dispersion stabilizer and the rotation speed of a forced disperser such as a homomixer. By adjusting droplets having a desired particle size and subsequently polymerizing, polymer fine particles of 2 to 300 μm can be arbitrarily produced. The polymerization temperature in the polymerization reaction of the present invention varies depending on the type of the polymerization initiator used, the monomer and the polymerization inhibitor optionally added, the chain transfer agent and the like, but is usually 30 to 100 ° C, preferably 50 to 100 ° C. 90 ° C. After the suspension polymerization, the spherical polymer fine particles are separated by filtration, washed with water, and dried to obtain fine particles having a regular wrinkle-like structure on the particle surface.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, "parts" represents parts by weight. Example 1 In a mixed solution of 75 parts of methyl methacrylate and 5 parts of ethylene glycol dimethacrylate, 20 parts of a styrene-butadiene-styrene block copolymer (KX408P, manufactured by Shell Japan K.K.) and 0.5 part of azobisisovaleronitrile were dissolved. 25 parts of a 10% aqueous solution of polyvinyl alcohol (PVA205, manufactured by Kuraray Co., Ltd.), 1 part of a 1% ethylene oxide-propylene oxide nonionic surfactant (Pronon 208, manufactured by NOF Corporation) and ion-exchanged water 275 parts were injected.
The resulting mixture is mixed with a homomixer (Special Kika Kogyo Co., Ltd.)
Was stirred at 7,000 rpm for 20 minutes to prepare a raw material dispersion. This raw material dispersion was charged into a polymerization reaction vessel equipped with a stirrer and a reflux condenser, and the temperature was raised to 80 ° C. while stirring under a nitrogen stream to carry out polymerization for 3 hours. The obtained polymer fine particle dispersion was dehydrated, washed, dried, and sieved to obtain 85 parts by weight of polymer fine particles having an average particle diameter of 36 μm and having a wrinkle-like structure on the surface of the particles (FIG. 1).

Example 2 A mixture of 75 parts of methyl methacrylate and 5 parts of ethylene glycol dimethacrylate was mixed with 15 parts of a styrene-isoprene-styrene block copolymer (D-1107CP, manufactured by Shell Japan KK) and polybutene (Nippon Petrochemical Co., Ltd.). 5 parts of Nisseki Polybutene HV300) and 0.5 part of azobisisovaleronitrile were dissolved in the same manner as in Example 1 (however, the rotation speed of the homomixer was 9,000 rpm) to obtain an average particle size. 86 parts by weight of polymer fine particles having a wrinkle-like structure on the surface with a diameter of 21 μm (FIG. 2) were obtained. Example 3 To the monomer mixture of Example 1 was added 5 parts of toluene,
Otherwise, the same operation was performed to obtain 86 parts by weight of polymer fine particles having an average particle diameter of 30 μm and having slightly larger wrinkles on the particle surface. Comparative Example 1 The same operation was performed as in Example 1 except that the amount of the block copolymer was changed from 20 parts to 1 part, but spherical polymer fine particles having a smooth particle surface and a wrinkle-like structure could be obtained. Did not. Comparative Example 2 The same operation was performed as in Example 1 except that 5 parts of ethylene glycol dimethacrylate was not added, but the particle surface was smooth, and polymer fine particles having a wrinkle-like structure could not be obtained.

[0012]

According to the present invention, a styrene-based elastomer is dissolved in a mixture of a hydrophobic polymerizable vinyl polymer and a crosslinkable monomer, and this is subjected to suspension polymerization in an aqueous medium to form a regular surface on the mixture. Spherical polymer fine particles having a wrinkle structure can be obtained. The spherical polymer particles having a unique surface structure obtained in this way give a uniform composition that does not cause layer separation when blended in, for example, paints and cosmetics, and change its viscosity, light scattering and surface properties. , Can be advantageously used for adjustment. In particular, it exerts its power as a matting agent in paints.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of the polymer fine particles obtained in Example 1.

FIG. 2 is an electron micrograph of the polymer fine particles obtained in Example 2.

Claims (4)

[Claims] 1. Spherical polymer fine particles having a regular wrinkle-like structure on the surface. 2. The spherical polymer fine particles according to claim 1, having an average particle size of 2 to 300 μm. 3. A hydrophobic polymerizable vinyl monomer 40 to 90.
A method for producing spherical polymer fine particles having a regular wrinkle-like structure on the surface by dissolving 5 to 30 parts by weight of a styrene-based elastomer in a mixture of 1 part by weight and 1 to 40 parts by weight of a crosslinkable monomer and suspension polymerizing in an aqueous medium . 4. The method according to claim 3, wherein the polymerizable vinyl monomer is an alkyl (meth) acrylate.