JPH03190903A - Production of spherical crosslinked polymer particle - Google Patents

Abstract

PURPOSE:To readily obtain the title particles useful for powder coating compound having uniform particle size in a short time by polymerizing a monomer in a solvent which dissolves the monomer but not a polymer thereof, precipitating a radical built-in polymer, adding a crosslinkable monomer, etc., swelling the polymer and polymerizing. CONSTITUTION:A monomer (e.g. styrene) is radical-polymerized in a solvent (e.g. ethanol) which dissolves the monomer but not a polymer based on the monomer, radical built-in polymer particles are precipitated, further a monomer mixture containing a polyfunctional vinyl compound (e.g. divinylbenzene) is added to the polymer particles, which are swollen with the monomer, the radical built in the polymer particles is brought into contact with the monomer and the monomer is secondarily polymerized to give the objective spherical crosslinked polymer particles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing truly spherical crosslinked polymer particles.

[Background of the invention]

True spherical polymer particles can be used, for example, as raw materials for powder coatings, toners for electronic copying, as fillers for paints and cosmetics that exhibit good spreadability, as fillers for treatments such as adsorption treatment and ion exchange treatment that have high treatment efficiency, or as such fillers. It is currently attracting attention as a useful material for material carriers and fillers for imparting opalescent luster to plastic molded products.

[Conventional technology]

This type of true spherical polymer particles can be obtained by a precipitation polymerization method in which monomers are polymerized in a solvent that dissolves the monomers but does not dissolve the Shigetani bodies based on the monomers to precipitate the polymer. (Y, Almog et al., Polymer Journal Vol. 14, p. 131 (1982)).

Their method involves precipitation polymerization using a polymer soluble in the solvent together with a quaternary ammonium salt as a dispersion stabilizer to obtain true spherical polymer particles with uniform particle size. Furthermore, attempts have been made to obtain truly spherical polymer particles with uniform particle diameters by dispersion polymerizing styrene in various solvents using nonionic cellulose derivatives as dispersion stabilizers (C, , Ober et al., J.]-2-Nal of Bolimer Science, Vol. 23, p. 103 (
1,985)).

[Problem to be solved by the invention]

When using truly spherical polymer particles as fillers for paints, fillers for ion exchange treatment, etc., it is desirable to crosslink them in order to improve solvent resistance and mechanical strength. In order to obtain such crosslinked truly spherical polymer particles, a polyvalent vinyl compound such as divinylbenzene or diallyl phthalate is added to the monomer, but in the above precipitation polymerization method, such When a polyvalent vinyl compound is mixed, there is a problem in that only polymer particles having a low sphericity, a rainbow shape, distortion, and non-uniform particle size are obtained.

[Means to solve the problem]

The present invention, as a means for solving the above-mentioned conventional problems,
A primary polymerization step of polymerizing the monomer in a solvent in which the monomer is dissolved but not the polymer based on the monomer to precipitate polymer particles containing radicals; A secondary polymerization step in which a monomer containing a compound is added to swell the polymer particles with the monomer, and radicals contained in the polymer particles are brought into contact with the monomer to perform polymerization. The present invention provides a method for producing truly spherical crosslinked polymer particles comprising:

[Monomer]

Monomers used in the present invention include methyl acrylate, ethyl acrylate, n-butyl acrylate, 1
so-butyl acrylate, 2-ethylhexyl acrylate-1, cyclohexyl acrylate, tetrahydrofurfurylacryl no 1-, methyl methacrylate,
Ethyl methacrylate, n-butyl methacrylate, 1
so-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, sO-butyl vinyl ether n-butyl vinyl ether, styrene,
α-methylstyrene, acryloni-1-lyl, methacrylate tril, vinyl acetate, vinyl chloride, vinylidene chloride,
Examples include vinyl fluoride, vinylizone fluoride, ethylene, propylene, isoprene, chloroprene, and butadiene. The above examples are not intended to limit the invention.

In addition, monomers having a functional group such as a carboxyl group, a hydroxyl group, a methylol group, an amino group, an acid amide group, or a glycidyl group may be mixed with the monomers mentioned above. As monomers having the above functional groups, those having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, etc., and those having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β -Hydroxypropyl methacrylate-1~, allyl alcohol, etc. Those with a methylol group are N-methylol acrylamide, N-methylol methacrylamide, etc. Those with an amino group are dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, etc. Examples of those having an amide group include acrylamide and methacrylamide, and examples of those having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, and glycidyl allyl ether. ”-The above examples are not intended to limit the present invention.

Furthermore, in the present invention, monomers having a hydrolyzable silyl group, such as γ-
Methacryloxypropyltrimethoxysilane, vinyl 1
Heliacetoxylan, vinyltrimethoxysilane, etc. can also be used. The above examples are also not intended to limit the invention.

[Polyvalent vinyl compound] Examples of the polyvalent vinyl compound containing two or more vinyl groups used in the present invention include divinylbenzene, diallyl phthalate, ethylene glycol diacrylate, ethyl nonglycol dimethacrylate I note, and propylene glycol dimethacrylate. to ray-1, propylene glycol diacrylate-1-1I to rimethylolpropane trimethacrylate-
1, trimethylolpropane triacrylate-1, glycerin trimethacrylate-1, and the like. The above-mentioned polyvalent vinyl compound is usually added to the monomer in an amount of 0.01% by weight or more. Further, these polyvalent vinyl compounds may be used alone or in combination.

〔solvent〕

The solvent used in this method is one in which the above-mentioned heavy body is dissolved and the q
The copolymer based on the t-heavy weight substance does not dissolve, and it cannot be dissolved in a lower alcohol such as methanol, ethanol, impropatol, or n-butanol, or a mixed solvent of the lower alcohol and water, or n-hexane, rhohebutane, etc. Examples include non-polar solvents. - The above examples are not intended to limit the invention.

[Dispersion stabilizer]

As the dispersion stabilizer, polymers soluble in the above solvents are used, such as polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyvinyl alcohol, polyvinyl alkyl ether, etc. If desired, a surfactant may be used in addition to the above polymers. May be used together. Any of anionic, nonionic, and cationic surfactants can be used as the surfactant. Examples of anionic surfactants include higher alcohol sulfur-1 (Na salt or amine salt).
, alkylaryl sulfonate (Na salt), alkylnaphthalene sulfonate, alkyl phosphate,
Dialkyl sulfosuccinate, rosin soap, nonionic polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether,
Polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkyl amide, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester, trimethylaminoethyl alkylamide halogenide as a cationic one,
Examples include alkylpyridinium sulfate and alkyltrimethylammonium halide. The above examples are also not intended to limit the invention.

” The polymer mentioned above is usually 0.5 to 20% by weight in the above solvent,
The above-mentioned surfactant is usually dissolved in the above-mentioned solvent in an amount of about 0.1 to 3%. The above-mentioned polymer and the above-mentioned surfactant may be mixed together.

7- [Polymerization] Examples of polymerization initiators used in the polymerization of the above comonomers include lauroyl peroxide, hensyl peroxide, cumene hydroperoxide, azobisisobutyronitrile, and 2,2'-azobis( An oil-soluble or oil-water soluble initiator such as 2-methyl-N-phenylpropionamidine) dihydrochloride is used. The oil-soluble or oil-water soluble initiator is usually used in an amount of 0.0% relative to the comonomer.
It is twisted by 1 to 8% by weight.

In the primary polymerization step, the above monomer is usually used in an amount of 1-0 to 65% by weight based on the solvent. The mixture of the 1-mer and the above-mentioned solvent is then heated and stirred using the above-mentioned oil-soluble or oil-water-soluble initiator in a reactor equipped with a stirrer, condenser, thermometer, etc., usually at a temperature of about 50 to 80°C. and polymerize. At this time, in order to smooth the polymerization, it is desirable to replace most of the air in the reactor with an inert gas such as nitrogen gas or argon gas.

As the monomer polymerizes, the monomer becomes a polymer and is precipitated in the solvent as true spherical particles. The monomer polymer has terminal radicals during growth, but the radicals are confined within the polymer particles rather than emerging on the surface of the particles.

Therefore, at a stage where polymerization has progressed to a certain extent, radicals are contained approximately in the center of the precipitated polymer particles. At this point, a secondary polymerization step begins.

In the secondary polymerization process, the monomers used are the same or different from those used in the primary polymerization process, but the polymers produced in the primary polymerization process that contain the above polyvalent vinyl compound It is necessary that the particles swell. The monomer used in the secondary polymerization step usually contains 0.01% by weight or more of the above-mentioned polyvalent vinyl compound, and the amount of the monomer is usually 1 to 1% of the polymer particles produced in the secondary polymerization step. It is said to be about 200% heavy view. In the secondary polymerization process, the monomer added swells the polymer particles produced in the secondary polymerization process, penetrates into the interior, reaches the center, and comes into contact with the radicals built into the polymer particles. Polymerization is initiated in this way, and secondary polymerization is carried out in this way.

Since the secondary polymerization step can be performed successively to the primary polymerization step, the primary polymerization step can be performed in the same reactor without changing the reactor or isolating the polymer particles produced in the secondary polymerization step. Immediately after the completion of the polymerization, monomers to be used in the secondary polymerization step are added to the reactor. The reaction temperature in the secondary polymerization step is usually about 50 DEG -80 DEG C. as in the secondary polymerization step, and preferably the polymerization is carried out under an inert gas atmosphere as in the primary polymerization step. After the completion of the secondary polymerization process, the obtained truly spherical crosslinked polymer particles are separated into five units.
After separation from the solvent by centrifugation or the like and washing if desired, drying is carried out at room temperature or with heating.

In this way, the true spherical crosslinked polymer particles of the present invention are obtained, and the diameter of the true spherical crosslinked polymer particles is influenced by the type of monomer and solvent or the amount of polyvalent vinyl compound added, but approximately It is in the range of about 0.5 to 10 μm and is uniform.

[Effect]

The polymer particles produced in the primary polymerization step contain radicals approximately in the center. In the secondary polymerization step, the polymer particles are swollen with a monomer containing a polyvalent vinyl compound, but even in the swollen state, the polymer particles maintain their original true spherical shape and swell. do. The monomer that has swollen the polymer particles and penetrated into the inside of the particles does not start polymerization until it comes into contact with radicals in the center of the particles. Therefore, in the secondary polymerization step, polymerization of the monomer occurs because the polymer particles are completely swollen with the monomer. In this way, the crosslinked polymer particles of the present invention are obtained when the monomer that has permeated the polymer particles is completely polymerized.
The crosslinked polymer particles inherit the true spherical shape of the original combined particles produced in the primary polymerization step, and have a size that is expanded by swelling.

〔Effect of the invention〕

Therefore, in the present invention, crosslinked polymer particles having a nearly perfect spherical shape and having a uniform particle size can be obtained easily and quickly in two consecutive steps in one reactor.

1 [Example] Example 1 (-Subpolymerization step) A solution of 4 parts by weight of -30 dissolved in polyvinylpyrrolidone in 160 parts by weight of ethanol was placed in a reactor equipped with a stirrer, a condenser, a thermometer, and a gas introduction tube. After filling the tank with 0.6 parts by weight of benzoyl peroxide dissolved in a comonomer prepared by mixing 60 parts by weight of styrene and 2 parts by weight of methacrylic acid, the tank was replaced with nitrogen through the gas introduction pipe.
When polymerization is carried out for 24 hours by heating the internal temperature to 70° C. while stirring and mixing at a rotational speed of 35 Qrpm, polymer particles containing radicals are precipitated.

The particle size of a small amount of the obtained polymer particles was measured using a scanning electron microscope photograph, and the particle size was 7.1±0.5 μm.

(Secondary polymerization step) After the above-mentioned secondary polymerization step, 10 parts by weight of styrene, 0.5 parts by weight of methacrylic acid, and 10 parts by weight of divinylbenzene were immediately mixed while maintaining the internal temperature at 70°C. The body was put into a reactor and secondary polymerization was carried out for 6 hours.

After the above secondary polymerization reaction, the resulting polymer particles were cooled to room temperature and collected in a separate furnace, washed with isopropanol and heated to 60°C.
Dry with ventilation for 2 hours. The particle size of 100 randomly selected polymer particles obtained in this way was measured using a scanning electron microscope photograph, and the result was 7.6 ± 0.5 μm.
It was found to be perfectly spherical with a uniformly distributed particle size of .

Example 2 (-Next Polymerization Step) A reactor similar to Example 1 was charged with 160 parts by weight of isopropanol in which 4 parts by weight of polyacrylic acid was dissolved, and 0.3 parts by weight of benzoyl peroxide was dissolved therein. A comonomer of 30 parts by weight of styrene and 2 parts by weight of β-hydroxyethyl methacrylate was further charged and polymerization was carried out in the same manner as in Example 1.

When the particle size of the obtained polymer particles was measured in the same manner as in Example 1, it was found to be 5.2±0.3 μm.

13-4- (Secondary polymerization step) -1-- After the second polymerization step, 20 parts by weight of divinylbenzene is charged into the reactor in the same manner as in Example 1 to carry out secondary polymerization.

The resulting polymer particles were perfectly spherical with a uniformly distributed particle size of 5.7±0.3 μm.

Example 3 (-・Next polymerization process) Polyvinyl methyl ether 3 was placed in the same reactor as in Example].
Parts by weight, filled with polyoxyethylene alkyl needle 1 - methanol in which the heavy weight part is dissolved] - 60 weight part,
A comonomer with 20 parts by weight of styrene, 10 parts by weight of acrylonitrile, and 1-2 parts by weight of dimethylaminoethyl methacrylate in which 0.5 parts by weight of azobisisobutyronitrile is dissolved. It is further filled and polymerized in the same manner as in Example 1.

The particle size of the obtained polymer particles was measured in the same manner as in Example 1--, and the particle size was 3.3±0.2 μm.

(Secondary polymerization step) After the above-mentioned secondary polymerization step, 30 parts by weight of styrene, 0 parts by weight of divinylbenzene, and 1 to 2 parts by weight of dimethylaminoethyl methacrylate were added to the reactor in the same manner as in Example]. to carry out secondary polymerization.

The resulting polymer particles were perfectly spherical with a uniformly distributed particle size of 4.2±0.2 μm.

Example 4 (-Next polymerization step) A reactor similar to Example 1 was charged with 1-60 parts by weight of methanol in which 1 part by weight of sodium alkylbenzenesulfonate was dissolved, and 0.5 parts by weight of benzoyl peroxide was dissolved therein. Example 1
It polymerizes in the same way as.

The particle size of the obtained polymer particles was measured in the same manner as in Example 1, and the particle size was 3.0±0.2 μm.

(Second polymerization step) 15 6 -I- After the second polymerization step, 1 to 10 parts by weight of methyl methacrylate and divinylbenzene were added in the same manner as in Example 1.
Part by weight is charged into a reactor to perform secondary polymerization.

The resulting polymer particles were perfectly spherical with a uniformly distributed particle size of 3.4±0.2 μm.

Claims (1)

[Claims] A primary polymerization step of polymerizing the monomer in a solvent in which the monomer is dissolved but not the polymer based on the monomer to precipitate polymer particles containing radicals; A secondary polymerization step in which a monomer containing a compound is added to swell the polymer particles with the monomer, and radicals contained in the polymer particles are brought into contact with the monomer to perform polymerization. A method for producing true spherical crosslinked polymer particles characterized by comprising: