JPH0611770B2 - Method for producing dispersion of heat-resistant fine resin particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a dispersion liquid of fine resin particles having excellent heat resistance and solvent resistance, more specifically, a maleimide compound as a main component. The present invention relates to a method for obtaining a dispersion of heat-resistant resin particles having a particle size of 100 μm or less and having a relatively narrow particle size distribution by emulsion-polymerizing or suspension-polymerizing a polymerizable monomer.

(Problems to be Solved by Conventional Techniques and Inventions) Fine resin particles have been conventionally used as pigments and fillers such as molded products, paints and adhesives. At present, there are problems such as insufficient solvent properties and generation of decomposition gas.

In view of these facts, the present inventors have earnestly studied, as a result of emulsion polymerization or suspension polymerization of a solution prepared by dissolving a polymerizable monomer containing a maleimide compound in a specific organic solvent, the particle diameter Of 100 micron or less, it was found that a dispersion containing fine resin particles having a relatively narrow particle size distribution and excellent heat resistance and solvent resistance can be easily obtained, and the present invention was completed. It is a thing.

(Means and Effects for Solving Problems) That is, the present invention has 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, R ₃ is hydrogen, an alkyl group having 1 to 15 carbon atoms, A cycloalkyl group, an aryl group or a substituted aryl group.) A polymerizable monomer containing a maleimide compound represented by The present invention relates to a method for producing a dispersion of heat-resistant fine resin particles, which comprises subjecting a solution obtained by dissolving a polymer obtained in a hydrophobic organic solvent to emulsion polymerization or suspension polymerization.

The maleimide compound used in the present invention is represented by the above general formula, for example, maleimide, N-
Methyl maleimide, N-ethyl maleimide, N-propyl maleimide, N-isopropyl maleimide, N-butyl maleimide, N-isobutyl maleimide, N-tertiary butyl maleimide, N-cyclohexyl maleimide, N-lauryl maleimide, N-phenyl maleimide, N- (2-chlorophenyl) maleimide, N- (3
-Chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, N- (4-bromophenyl) maleimide, N- (2,4,6-trichlorophenyl) maleimide, N- (2,4,6-tri) Bromophenyl) maleimide, N- (2-methylphenyl) maleimide, N-
(3-Methylphenyl) maleimide, N- (4-methylphenyl) maleimide, N- (2-tert-butylphenyl) maleimide, N- (3-tertiarybutylphenyl) maleimide, N- (4-tertiarybutyl) Phenyl) maleimide, N- (2,6-dimethylphenyl) maleimide, N- (2-nitrophenyl) maleimide, N
-(3-Nitrophenyl) maleimide, N- (4-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-
Examples thereof include N-phenylmaleimide and α-methyl-N-phenylmaleimide, and of these, one kind or two or more kinds can be used.

The polymerizable monomer used in the present invention comprises the above-mentioned maleimide compound, and in consideration of the required heat resistance and solvent resistance, the heat resistance of the obtained fine resin particles and the solvent resistance are impaired. Other monomers that can be copolymerized with the maleimide compound can be used in combination as long as the amount does not exist. Preferably, another monomer is used in combination in such a proportion that the maleimide compound is the main component of the polymerizable monomer. When the amount of the other monomer used exceeds the ratio of the maleimide compound as the main component of the polymerizable monomer, the heat resistance of the resulting resin particles may be insufficient in some cases, or the solvent resistance There is a case where the sex is deteriorated.

As these other monomers, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, C1-C18 alkyl groups such as octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-phenoxyethyl methacrylate, 3-phenylpropyl methacrylate, etc. Methacrylic acid esters having; methyl acrylate, ethyl acrylate, propyl acrylate, persopropyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, Acrylic esters having an alkyl group having 1 to 18 carbon atoms such as amyl lylate, isoamyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, cyclohexyl acrylate, and benzyl acrylate; Vinyl aromatics such as styrene, α-methylstyrene, paramethylstyrene, vinyltoluene, isopropenylstyrene and chlorostyrene; unsaturated nitriles such as acrylonitrile, methacrylonitrile, ethacrylonitrile and phenylacrylonitrile; ethylene glycol diacrylate Or methacrylate, hexanediol diacrylate or methacrylate, divinylbenzene, trimethylolpropane triacrylate or methacrylate, pentaerythritol tetraacryiate Rate or methacrylate, dipentaerythritol hexaacrylate or methacrylate, diacrylate or methacrylate of ethylene oxide or propylene oxide adduct of bisphenol A, halogenated bisphenol A
Polyacrylates or methacrylates such as diacrylates or methacrylates of ethylene oxide or propylene oxide adducts, triacrylates or methacrylates of isocyanurates, di- or triacrylates of isocyanurates ethylene oxide or propylene oxide adducts; Polyvalent allylates such as allyl isocyanurate and diallyl phthalate; further functional units such as glycidyl acrylate or methacrylate, allyl glycidyl ether, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid or their half-esterified products The body and the like can be mentioned, and one or more of these can be used according to the purpose, but the types and the amounts used are within the range not departing from the object of the present invention. It may be set-option.

The resin particles contained in the dispersion liquid of the heat-resistant fine resin particles obtained by the method of the present invention are spherical fine particles having a size of 0.01 to 100 μm. The dispersion liquid of the fine particles can be easily obtained by way of emulsion polymerization or suspension polymerization of the polymerizable monomer. In the polymerization, a hydrophobic liquid which dissolves the polymerizable monomer but does not dissolve the polymer is obtained. It is obtained by polymerizing a solution in which the polymerizable monomer is dissolved in a polar organic solvent by the polymerization method.

Most maleimide compounds are solid at room temperature. Therefore, the conventional method has various restrictions when emulsion-polymerizing or suspension-polymerizing a monomer containing a maleimide compound as a main component. For example, after heating the maleimide compound above the melting point,
It is necessary to polymerize in an emulsified state or in a suspended state, or it is necessary to dissolve the maleimide compound in a larger amount of other polymerizable monomer than necessary and then subject it to polymerization.
In addition, there is also a constraint that the process becomes complicated, for example, a complicated operation is required for controlling the particle size distribution of the fine resin particles contained in the obtained dispersion liquid. However, the method of the present invention in which a monomer containing a maleimide compound as a main component is polymerized into a solution in which a polymer that dissolves the monomer is dissolved in a hydrophobic organic solvent that is not dissolved does not use an organic solvent. There is no penalty as in the case of the method. That is, the polymerization can proceed at any polymerization temperature regardless of the melting point of the maleimide compound, and since the organic solvent does not dissolve the polymer, polymer particles of the obtained emulsion or suspension are fused. And the control of the particle size of the resin particles finally obtained becomes extremely easy.

In the conventional method, when polymerizing at a temperature higher than the melting point of the maleimide compound, there is a problem that the emulsion or suspension polymerization system becomes unstable and a dispersion containing fine resin particles having a desired particle size cannot be obtained, or more than necessary. When a large amount of other polymerizable monomer is used in combination, the heat resistance of the resulting fine resin particles is inferior, whereas according to the method of the present invention, a high melting point maleimide compound is used. It is possible to easily obtain fine resin particles having a desired particle size from the polymerizable monomer contained in, and as a result, the heat resistance of the resin particles can be made extremely high.

The organic solvent solution concentration of the polymerizable monomer depends on the type of the monomer, the type of the organic solvent and the temperature at the time of dissolution, but the particle size of the obtained polymer, the molecular weight of the polymer, the polymerization conditions and the economical efficiency. The conditions may be appropriately selected in consideration of the above. For example, various choices can be made, such as when the monomer is dissolved in an organic solvent at room temperature and then polymerized, or when the monomer is dissolved under heating and then polymerized.

The organic solvent used in the present invention is particularly a hydrophobic organic solvent which dissolves a polymerizable monomer containing a maleimide compound but does not dissolve a polymer obtained by polymerizing the polymerizable monomer. Without limitation, for example, hexane, heptane, cyclohexane, decane, benzenetoluene, xylene, ethylbenzene, p-cymene, decalin, solvent naphtha, and other aliphatic or aromatic hydrocarbons; chloroform,
Halogenated hydrocarbons such as trichloroethane; amyl alcohol, n-butanol, sec-butanol, n-
Alcohols such as hexanol, cyclohexanol and benzyl alcohol; ketones such as methyl isobutyl ketone, isophorone and methyl cyclohexanone; esters such as butyl acetate, isobutyl acetate, methyl acetoacetate, ethyl acetoacetate and butyl carbitol acetate. These can be used alone or in combination of two or more.

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

The polymerization initiator used in the polymerization is a conventionally known free radical polymerization initiator such as benzoyl peroxide, lauryl peroxide, hydrogen peroxide, potassium peroxide, and an oil-soluble or water-soluble peroxide such as ammonium persulfate. Azo compounds such as azobisisobutyronitrile are suitable. It is also possible to effectively proceed with the polymerization reaction by using a reducing agent such as dimethylaniline, sodium hydrogen sulfite, ascorbic acid and ferrous sulfate together.

Examples of emulsifiers used in emulsion polymerization include anionic emulsifiers such as potassium oleate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate;
Polyoxyethylene polyoxypropylene block copolymer, nonionic emulsifiers such as polyoxyethylene sorbitan ester; cationic emulsifiers such as lauryltrimethylammonium chloride may be used as appropriate,
Of these, it is preferable to mainly use an anionic emulsifier.

Examples of the suspending agent used in suspension polymerization include polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, water-soluble salts of acrylic acid or methacrylic acid copolymers, organic suspending agents such as the above nonionic emulsifiers; magnesium carbonate, Inorganic suspension agents such as calcium carbonate and barium sulfate may be used.

The molecular weight of the polymer obtained by the polymerization is not particularly limited, but it is preferably higher from the viewpoint of heat resistance.
When it is necessary to control the molecular weight, known chain transfer agents such as butyl mercaptan, tert-dodecyl mercaptan, mercaptoethanol, carbon tetrachloride and the like may be used.

Further, for the purpose of maintaining the stability of the particles during the polymerization and controlling the particle size, known pH adjusters, various salts and the like can be supplementarily used.

The heat-resistant fine resin particles contained in the dispersion obtained by the method of the present invention are spherical fine particles having a diameter in the range of 0.01 to 100 microns. Since it is preferable that the particle size distribution of the fine resin particles is practically narrow, in order to control the particle size distribution,
By combining various requirements such as the type of organic solvent, the polymerization temperature, the polymerization initiator, the emulsifier or the suspending agent, the monomer concentration, the auxiliary, and the stirring, it is sufficient to obtain resin particles having a predetermined particle size distribution range. .

The fine resin particles contained in the dispersion liquid obtained by the method of the present invention have a relatively narrow particle size distribution, and are excellent in heat resistance, solvent resistance, lubricity, electrical characteristics, etc. It can be used for various purposes, for example, as a heat resistance improving agent for various plastics, a molding processability improving agent, a filling reinforcing agent, a tape such as a magnetic tape, a slip agent for films and the like.

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

Example 1 A 4-necked stainless steel flask equipped with a stirrer of 1 was charged with 411 parts of deionized water and 3 parts of sodium lauryl sulfate,
The mixture was heated to 60 ° C. under a nitrogen gas atmosphere to dissolve sodium lauryl sulfate and maintained at this temperature. Separately, a solution prepared by dissolving 124 parts of N-phenylmaleimide in 76 parts of toluene at 60 ° C. was added to a 4-necked flask and emulsified. After the internal temperature was raised to 70 ° C., 0.6 part of “Perbutyl H” (manufactured by NOF CORPORATION) as a polymerization initiator and 0.6 part of Rongalit as a reducing agent were added to initiate polymerization, and then 2 The temperature was maintained at 70 ° C. for another hour and further at 80 ° C. for 1 hour.

The obtained emulsion was a white emulsion having a viscosity of about 50 centipoise.

Observation of the fine resin particles contained in this emulsion with an electron microscope revealed that they were spherical particles having a particle diameter in the range of 0.1 to 0.3 micron. Further, the fine resin particles had a melting point of 300 ° C. or higher (Mettler melting point measuring device) and were insoluble in toluene.

Example 2 566.5 parts of deionized water and 5 parts of sodium dodecylbenzenesulfonate were charged into a 4-necked stainless steel flask equipped with a stirrer of 1, and heated to 50 ° C. under a nitrogen gas atmosphere to sodium dodecylbenzenesulfonate. Was dissolved and maintained at this temperature. Separately, a solution prepared by dissolving 125 parts of N-cyclohexylmaleimide, 67.5 parts of methyl methacrylate and 1.25 parts of "Perbutyl H" (manufactured by NOF CORPORATION) in 57.5 parts of cyclohexane was added to a 4-neck flask. Emulsified. Then, an aqueous solution prepared by dissolving 1.25 parts of Rongalite in 10 parts of deionized water was added to initiate polymerization, and then the internal temperature was raised to 60 ° C. and kept at this temperature for 3 hours. During this period, 2 parts of the Rongalit aqueous solution was added in 6 batches to complete the polymerization.

The resulting dispersion was an emulsion with a viscosity of about 70 centipoise.

As a result of measuring the fine resin particles contained in this dispersion with an electron microscope, the particles were spherical particles having a particle diameter in the range of 0.1 to 0.3 micron. Further, the fine resin particles had a melting point of 300 ° C. or higher and were insoluble in cyclohexane.

Example 3 To a stainless steel flask equipped with a stirrer according to Example 1, 500.3 parts of an aqueous solution prepared by dissolving 0.3 part of polyvinyl alcohol in 500 parts of deionized water was charged, and the mixture was placed under a nitrogen gas atmosphere at 50 parts.
Warmed to ° C. Then, a solution prepared by dissolving 20 parts of N- (2-chlorophenyl) maleimide and 0.5 part of azobisisobutyronitrile in a mixed solvent of 40 parts of cyclohexane and 20 parts of toluene was charged into a flask and uniformly suspended. . The inner temperature of the flask was raised to 65 ° C. and kept at this temperature for 3 hours, and then the inner temperature was further raised to 75 ° C. and kept for 1 hour.

The obtained aqueous suspension was a low-viscosity sedimentary emulsion. When the fine resin particles contained in this emulsion were observed with a microscope, it was found that the particle diameter was in the range of 10 to 30 microns. The melting point was 300 ° C or higher.

Claims (1)

[Claims] 1. A 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, cyclo An alkyl group, an aryl group or a substituted aryl group.) A polymerizable monomer comprising a maleimide compound represented by the formula (1) is obtained by dissolving the polymerizable monomer and polymerizing the polymerizable monomer. A method for producing a dispersion of heat-resistant fine resin particles, which comprises subjecting a solution prepared by dissolving a polymer to be dissolved in a hydrophobic organic solvent which is not dissolved to emulsion polymerization or suspension polymerization.