JPH0422165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing fine resin particles having excellent heat resistance and solvent resistance.
The present invention relates to a method for obtaining heat-resistant resin particles having a particle size of 100 microns or less and a relatively narrow particle size distribution by polymerizing in an aqueous medium containing a specific organic solvent.

Fine resin particles have traditionally been widely used as pigments, extender pigments, and filling reinforcing agents for plastics, but some of these particles do not have sufficient heat resistance or solvent resistance, or generate decomposition gas. The current situation is that we are facing a problem.

In view of these circumstances, the present inventors conducted extensive research and found that after polymerizing a polymerizable monomer containing a maleimide compound in an aqueous medium containing a specific organic solvent, The present invention was completed based on the discovery that by separating and drying the aggregate, fine resin particles with a particle size of 100 microns or less, a relatively narrow particle size distribution, and excellent heat resistance can be easily obtained. It is something that

That is, the present invention is based on the general formula (In the formula, R ₁ and R ₂ are each independently hydrogen, halogen, an alkyl group having 1 to 15 carbon atoms, an aryl group, or a substituted aryl group, and R ₃ is hydrogen, an alkyl group having 1 to 15 carbon atoms, or a cyclo A polymerizable monomer comprising a maleimide compound represented by an alkyl group, an aryl group, or a substituted aryl group, and an organic solvent that dissolves the polymerizable monomer and is miscible with water. The present invention relates to a method for producing heat-resistant fine resin particles, which comprises polymerizing in an aqueous medium, followed by separating the polymer from the medium and drying it.

The maleimide compound used in the present invention is represented by the above general formula, and includes, for example, maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, and N-isobutylmaleimide. Maleimide, N-tertiarybutylmaleimide, N-cyclohexylmaleimide, N-laurylmaleimide, N-phenylmaleimide, N-
(2-chlorophenyl)maleimide, N-(3-chlorphenyl)maleimide, N-(4-chlorphenyl)maleimide, N-(4-bromophenyl)
Maleimide, N-(2,4,6-trichlorophenyl)maleimide, N-(2,4,6-tribromophenyl)maleimide, N-(2-methylphenyl)maleimide, N-(3-methylphenyl)
Maleimide, N-(4-methylphenyl)maleimide, N-(2-tertiarybutylphenyl)maleimide, N-(3-tertiarybutylphenyl)
Maleimide, N-(4-tertiarybutylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2-nitrophenyl)maleimide, N-(3-nitrophenyl)maleimide, N-(4-dimethylphenyl)maleimide, -nitrophenyl)maleimide, N
-(2,4-dinitrophenyl)maleimide, N
-(2-hydroxyphenyl)maleimide, N-
(3-hydroxyphenyl)maleimide, N-(4
-hydroxyphenyl)maleimide, N-(2-
methoxyphenyl)maleimide, N-(3-methoxyphenyl)maleimide, N-(4-methoxyphenyl)maleimide, N-(4-ethoxyphenyl)maleimide, N-(2-methoxy-4-chlorophenyl) Maleimide, N-(4-phenylphenyl)maleimide, N-(4-phenyloxyphenyl)maleimide, N-(4-benzylphenyl)maleimide, N-(4-benzyloxyphenyl)maleimide, N-( 4-phenoxymethylphenyl)maleimide, N-(2-chloro-4-
phenoxyphenyl)maleimide, N-naphthylmaleimide, N-(2-carboxyphenyl)maleimide, N-(4-carboxyphenyl)maleimide, α-chloro-N-phenylmaleimide,
Examples include α-methyl-N-phenylmaleimide, and one or more of these can be used.

The polymerizable monomer used in the present invention contains the above-mentioned maleimide compound, and takes into consideration the required heat resistance and solvent resistance, and impairs the heat resistance and solvent resistance of the resulting fine resin particles. Other monomers copolymerizable with the maleimide compound may be used in combination with the maleimide compound. Preferably, the maleimide compound is used in combination with other monomers in such a proportion that it becomes the main component of the polymerizable monomer. If the amount of other monomers used exceeds the ratio in which the maleimide compound is the main component of the polymerizable monomer, the heat resistance of the resulting resin particles may become insufficient, or the Complicated operations when separating and drying the polymer from the medium, such as spray drying or drying low compression cakes at relatively low temperatures (less than 100°C), facilitate the disintegration of the polymer and produce desirable particles. Care must be taken as this may be necessary in order to obtain resin particles with a fine diameter.

Examples of these other monomers include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, amyl methacrylate,
Isoamyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-phenoxyethyl methacrylate, 3-methacrylate
-C1 or more of alkyl group such as phenylpropyl
Methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, tertiary butyl acrylate, amyl acrylate, isoamyl acrylate, octyl acrylate, Acrylic acid esters having an alkyl group of 1 to 18 carbon atoms such as 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, cyclohexyl acrylate, and benzyl acrylate; styrene, α-methylstyrene, paramethylstyrene, vinyl Vinyl aromatics such as toluene, isopropenylstyrene, chlorstyrene; unsaturated nitriles such as acrylonitrile, methacrylonitrile, ethacrylonitrile, phenyl acrylonitrile; ethylene glycol diacrylate or methacrylate, hexanediol diacrylate or methacrylate, divinyl benzene, trimethylolpropane triacrylate or methacrylate, pentaerythritol tetraacrylate or methacrylate,
Dipentaerythritol hexaacrylate or methacrylate, diacrylate or methacrylate of ethylene oxide or propylene oxide adduct of bisphenol A, diacrylate or methacrylate of ethylene oxide or propylene oxide adduct of halogenated bisphenol A, triacrylate or isocyanurate Polyvalent acrylates or methacrylates such as methacrylate, di- or triacrylate or methacrylate of ethylene oxide or propylene oxide adducts of isocyanurate; polyvalent arylates such as triallyl isocyanurate and diallyl phthalate; furthermore, glycidyl acrylate or methacrylate, Allyl glycidyl ether, acrylic acid, methacrylic acid, itaconic acid,
Examples include functional monomers such as maleic acid, fumaric acid, and half-esterified products thereof, and one or more of these can be used depending on the purpose, but the types and amounts used are Any selection may be made without departing from the purpose of the present invention.

The heat-resistant fine resin particles obtained by the method of the present invention are
They are spherical fine particles with a size of 0.01 to 100 microns. The particles can be easily prepared by polymerizing the polymerizable monomer in an aqueous medium containing an organic solvent that dissolves the polymerizable monomer and is miscible with water.

The polymerization reaction is carried out under autogenous pressure or under pressure from a temperature of 0°C or lower under an inert gas atmosphere.
It is carried out at a temperature of 100°C or higher.

The polymerization initiators used in the polymerization include conventionally known free radical polymerization initiators such as oil-soluble or water-soluble peroxides such as benzoyl peroxide, lauryl peroxide, hydrogen peroxide, potassium persulfate, and ammonium persulfate. Azo compounds such as azobisisobutyronitrile are suitable. It is also possible to use a reducing agent such as dimethylaniline, sodium bisulfite, ascorbic acid, ferrous sulfate, etc. in combination to effectively advance the polymerization reaction.

In the present invention, polymerization of the polymerizable monomer is carried out in an aqueous medium containing an organic solvent that dissolves the polymerizable monomer and is miscible with water. At the initial stage of polymerization, the polymerizable monomer and the initial polymer are dissolved or finely dispersed in the aqueous medium, and as the polymerization progresses, fine particulate polymers with high molecular weight are generated in the aqueous medium. The particulate polymer produced during polymerization will not fuse and become coarse. The organic solvent is amphiphilic to water and the polymerizable monomer, and helps dissolve or finely disperse the polymerizable monomer and the initial polymer at the initial stage of polymerization, resulting in the formation of fine particles of polymer. This contributes to the stability of the produced particles in an aqueous medium.

In the present invention, in order to initiate polymerization in an aqueous medium, for example, a polymerizable monomer is added to an aqueous medium containing the organic solvent and mixed well to dissolve or finely disperse the polymerizable monomer. The method may be such that the polymerization is started later, or a solution of the polymerizable monomer dissolved in the organic solvent is added all at once to an aqueous medium or an aqueous medium containing the organic solvent, and then the polymerization is started. However, in order to further increase the stability of the produced polymer particles and thus obtain heat-resistant fine resin particles with a narrow particle size distribution, it is necessary to add the polymerizable monomer to the aqueous medium or the aqueous medium. A method in which polymerization is started after adding the organic solvent solution all at once is preferred.

The organic solvent used in the present invention is not particularly limited as long as it dissolves the polymerizable monomer and is miscible with water, such as methanol, ethanol, propanol, isopropanol, t-
Butanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate,
Methyl cellosolve acetate, diethyl carbitol, methyl carbitol, carbitol acetate, dioxane, tetrahydrofuran, dimethyl formamide, dimethyl form oxide, methyl ethyl ketone, acetone, methyl acetate, ethyl acetate, ethylene glycol, diethylene glycol, etc., and one type of these Or use two or more types.

In the present invention, polymerization is carried out in an aqueous medium containing the above-mentioned specific organic solvent, but in some cases, a small amount of a known emulsifier or suspending agent may be used in combination during the polymerization. However, when an emulsifier or a suspending agent is used in combination, care must be taken because the resulting fine resin particles often have high hygroscopicity, which may lead to a decrease in electrical properties of electrical insulation. According to the method of the present invention, heat-resistant resin particles having a relatively narrow particle size distribution can be easily obtained without using emulsifiers or suspending agents. Examples of emulsifiers include anionic emulsifiers such as potassium oleate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate; polyoxyethylene nonyl phenyl ether, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene sorbitan ester, etc. nonionic emulsifiers; cationic emulsifiers such as lauryltrimethylammonium chloride; suspending agents include, for example, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, water-soluble salts of acrylic acid or methacrylic acid copolymers, and the above-mentioned nonionic emulsifiers. Examples include organic suspending agents such as ionic emulsifiers; inorganic suspending agents such as magnesium carbonate, calcium carbonate, and barium sulfate. One or more of these may be used as appropriate. In addition, known PH regulators, various salts, etc. can be used to maintain the stability of fine particles during polymerization, or to use them as auxiliary agents for particle size control.

There is no particular restriction on the molecular weight of the polymer obtained by polymerization, but a higher one is preferable from the viewpoint of heat resistance. If it is necessary to adjust the molecular weight, a known chain transfer agent such as butyl mercaptan, tertiarydodecyl mercaptan, mercaptoethanol, carbon tetrachloride, etc. may be used.

The polymer obtained by polymerization as described above can be separated from the aqueous medium and dried to obtain fine resin particles by any conventional method, such as vacuum drying; spray drying; Any method can be adopted, such as adding an electrolyte or the like to an aqueous medium to salt out the polymer, and then passing through the steps of filtration, washing with water, and drying to obtain fine resin particles.

The heat-resistant fine resin particles obtained by the method of the present invention are spherical fine particles with a diameter ranging from 0.01 to 100 microns and a relatively narrow particle size distribution. In addition, it has excellent heat resistance, solvent resistance, lubricity, electrical properties, etc., and is hard, so it can be used for various purposes by taking advantage of these characteristics.
For example, it can be used as a heat resistance improver for various plastics, a molding processability improver, a filling reinforcing agent, tapes such as magnetic tape, and a slip agent for films.

Next, the present invention will be explained in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples. Note that in the examples, parts represent parts by weight, and % represents weight %.

Example 1 270 parts of deionized water and 270 parts of butyl cellosolve were placed in the four-necked stainless steel flask equipped with a stirrer in 1, heated to 50° C. under a nitrogen gas atmosphere, and maintained at this temperature. A solution prepared by dissolving 60 parts of N-ethylmaleimide and 0.6 parts of Perbutyl H (manufactured by NOF Corporation) in 180 parts of butyl cellosolve was added to a four-necked flask, and then 0.6 part of Rongalit was added to initiate polymerization. Thereafter, the internal temperature was raised to 70°C, and polymerization was continued for 3 hours.

The obtained aqueous liquid was dried under conditions of 100° C. and 10 mmHg to obtain fine resin particles.

When the obtained fine resin particles were observed using an electron microscope, they were found to be spherical particles with a particle size in the range of 0.1 to 10 microns.

In addition, the melting point measured with a Mettler melting point meter is
The temperature was over 300℃.

Example 2 270 parts of deionized water and 270 parts of butyl cellosolve were placed in the stainless steel flask equipped with a stirrer from 1.
It was heated to 60°C under nitrogen gas atmosphere and maintained at this temperature. 40 parts of N-cyclohexylmaleimide,
20 parts of methyl methacrylate to butyl cellosolve
A solution of 180 parts was added to the flask, and then 0.6 parts of azobisisobutyronitrile was added to initiate polymerization. After that, the internal temperature was raised to 70℃,
Polymerization was carried out at this temperature for 3 hours.

The obtained aqueous liquid was dried under the same conditions as in Example 1 to obtain fine resin particles. When observed with an electron microscope, it was found that the particles were spherical particles with a particle size in the range of 0.1 to 10 microns.

Moreover, the melting point was 300°C or higher.

Example 3 270 parts of deionized water was placed in the stainless steel flask equipped with a stirrer in step 1, and heated to 90°C under a nitrogen gas atmosphere.
and maintained at this temperature. 30 parts of N-phenylmaleimide, Perbutyl H (manufactured by NOF Corporation)
A solution of 0.3 parts dissolved in 270 parts of Cellosolve was added to the flask, followed by a 10% aqueous solution of Rongarit.
Polymerization was started by adding 1.5 parts. Polymerization start 1
After an hour, 1.5 parts of a 10% Rongalit aqueous solution was further added, and the polymerization was continued for 2 hours.

The obtained aqueous liquid was dried under the same conditions as in Example 1 to obtain fine resin particles. When this was observed using an optical microscope, it was found that it was a spherical particle with a size in the range of 0.5 to 15 microns.

It also showed high heat resistance, with a melting point of over 300°C.

Example 4 270 parts of deionized water and 270 parts of Cellosolve were placed in the stainless steel flask equipped with a stirrer from 1, and after heating to 85°C under a nitrogen gas atmosphere, 60 parts of N-cyclohexylmaleimide was added and dissolved. .

Next, 0.6 parts of Perbutyl H (manufactured by NOF Corporation) and 3 parts of a 10% aqueous solution of Rongarit were added to initiate polymerization. 1 hour after the start of polymerization, add 10% Rongalit
3 parts of aqueous solution was added and polymerization was continued for an additional 2 hours.

The obtained aqueous liquid was dried under the same conditions as in Example 1 to obtain fine resin particles. When this was observed with an optical microscope, it was found to be spherical particles with a particle size in the range of 0.5 to 15 microns.

It also showed high heat resistance, with a melting point of over 300°C.

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ and R ₂ are each independently hydrogen, halogen, an alkyl group having 1 to 15 carbon atoms, an aryl group, or a substituted aryl group, and R ₃ is hydrogen or a substituted aryl group having 1 to 15 carbon atoms.)
-15 alkyl, cycloalkyl, aryl or substituted aryl groups. ) is polymerized in an aqueous medium containing an organic solvent that dissolves the polymerizable monomer and is miscible with water, and then the medium A method for producing heat-resistant fine resin particles, characterized by separating and drying a polymer.