JPH0556364B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION The present invention relates to a novel method for producing a maleimide copolymer with high efficiency using (N-substituted) maleamic acid and a vinyl compound as starting materials. Copolymers consisting of maleic anhydride and aromatic vinyl compounds have long been known as polymers with excellent heat resistance, and are widely used alone or in compositions mixed with other resins.
It has the disadvantage of being prone to thermal decomposition during granulation or molding. Furthermore, polymers with better heat resistance are required in the field of use. For this reason, in recent years, thermal stability and heat resistance have been improved by polymerizing maleic anhydride-based polymers and then imidizing the acid anhydride groups of the polymers at high temperatures using ammonia or primary amines. Technology for producing maleimide copolymers (opening 56-39651, opening
57-55901, open 57-100104, open 57-125242, open 58
-180506, etc.), but since maleic anhydride is hydrolyzed to maleic acid in an aqueous system, it is difficult to produce a maleic anhydride-based copolymer, such as a maleic anhydride-styrene copolymer, in an aqueous system. cannot be used, and is limited to bulk polymerization systems or organic solvent systems. In addition, imidization of acid anhydride groups requires a long reaction time, and
It has the problem that it is extremely difficult to convert it to 100% maleimide. Structure of the Invention As a result of intensive research in view of the above-mentioned problems in the method for producing maleimide copolymers, the present inventors found that
In copolymerization of (N-substituted) maleamic acid and vinyl compound, before, during or after polymerization
By adding _C1-3 carboxylic acid alkali metal salt and acetic anhydride and then imidizing _,
We have developed a manufacturing method to obtain maleimide copolymers with high efficiency. Furthermore, the polymerization and maleimidization of the present invention can be carried out in an aqueous system, which has conventionally been impossible when maleic anhydride is used as a starting material. The present invention will be explained in more detail. Rubbers that can be present during the copolymerization of (N-substituted) maleamic acid and a vinyl compound include conjugated diene rubbers such as polybutadiene, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, and ethylene-propylene rubber. Examples include ethylene-propylene rubber such as propylene-nonconjugated diene rubber, acrylic rubber such as butyl acrylate rubber, chlorinated polyethylene, and ethylene-vinyl acetate rubber. o Maleamic acid and N-substituted maleamic acid The (N-substituted) maleamic acid used in the present invention is a compound represented by the following general formula. (However, R represents hydrogen, an alkyl group, or an aryl group.) Specifically, maleamic acid, N-methylmaleamic acid, N-ethylmaleamic acid, N-isopropylmaleamic acid, N-butylmaleamine acid, N
-hexylmaleamic acid, N-octylmaleamic acid, N-laurylmaleamic acid, N-cyclohexylmaleamic acid, N-2,3 or 4-methylphenylmaleamic acid, N-2,3 or 4-
Ethylmaleamic acid, N-2,3 or 4-butylphenylmaleamic acid, N-2,6-dimethylmaleamic acid, N-2,3 or 4-chlorophenylmaleamic acid, N-2,3 or 4-bromophenylmaleamic acid, N-2,5-dichloromaleamic acid, N-3,4-dichloromaleamic acid, N-2,5-dibromomaleamic acid, N-
3,4-dibromomaleamic acid, N-2,4,6
- trichloromaleamic acid, N-2,4,6-tribromomaleamic acid, N-2,3 or 4-hydroxyphenylmaleamic acid, N-2,3 or 4-methoxyphenylmaleamic acid, N-2,
3 or 4-carboxyphenyl maleamic acid,
N-4-nitrophenylmaleamic acid, N-4-
Diphenylmaleamic acid, N-1-naphthylphenylmaleamic acid, N-4-cyanophenylmaleamic acid, N-4-phenoxyphenylmaleamic acid, N-4-benzylphenylmaleamic acid ,
Examples include N-2-methyl-5-chlorophenylmaleamic acid and N-2-methoxy-5-chlorophenylmaleamic acid, and one or more of these may be used.
Preference is given to N-substituted maleamic acids, especially N-phenylmaleamic acids. o Vinyl compound The vinyl compound copolymerized with the above-mentioned (N-substituted) maleamine compound is one or more compounds selected from the group consisting of aromatic vinyl compounds, vinyl cyanide compounds, and unsaturated carboxylic acid alkyl ester compounds. be. Examples of aromatic vinyl compounds include styrene, α-
Methylstyrene, α-chlorostyrene, Pt-
Examples include butylstyrene, P-methylstyrene, O-chlorostyrene, P-chlorostyrene, 2,5-dichlorostyrene, 3,4-dichlorostyrene, and styrene is particularly preferred. Examples of vinyl cyanide compounds include acrylonitrile and methacrylonitrile, with acrylonitrile being particularly preferred. Furthermore, examples of the unsaturated carboxylic acid alkyl ester compound include acrylic ester compounds and methacrylic ester compounds such as methyl, ethyl, propyl, butyl, benzyl, and hexyl, and methyl methacrylate is particularly preferred. There are no restrictions on the ratio of (N-substituted) maleamic acid and vinyl compound, but (N-substituted) maleamic acid 1 to 80% by weight and vinyl compound 99 to 20% by weight.
It is preferable from the viewpoint of heat resistance etc. In addition,
When polymerized in the presence of rubber, the rubber is (N-
Substitution) Maleamic acid and vinyl compound total 100
Preferably, the amount is 5 to 200 parts by weight. The polymerization of the (N-substituted) maleamic acid and the vinyl compound can be carried out by a known emulsion polymerization method, suspension polymerization method, bulk polymerization method, solution polymerization method, or a combination thereof. o Alkali metal salts of carboxylic acids having 1 to 3 carbon atoms In the copolymerization of (N-substituted) maleamic acid and vinyl compounds, as alkali metal salts of C ₁ to ₃ carboxylic acids added before, during, or after polymerization. Examples include sodium acetate, potassium acetate, sodium formate, potassium propionate, etc.
One or more types can be used. There is no particular restriction on the amount of the alkali metal salt of _C1-3 carboxylic acid added, but from the viewpoint of imidization of maleamic acid, the amount of (N _- substituted) maleamic acid used is
It is preferably 0.01 to 0.5 molar equivalent. o _There is no particular restriction on the amount of acetic anhydride added together with the alkali metal salt of acetic acid _C1-3 carboxylic acid.
Used for imidization of maleamic acid (N
-Substituted) maleamic acid is preferably 1 molar equivalent or more. C ₁ to ₃ carboxylic acid alkali metal salts and acetic anhydride may be mixed with (N-substituted) maleamic acid and a vinyl compound before copolymerization, or may be added during copolymerization, and furthermore, may be added during copolymerization. It may be added to the polymerization tank after completion. Of course, it may be added after recovering the copolymer. Furthermore, the alkali metal salt of C ₁ to ₃ carboxylic acid and acetic anhydride can be used at the same time or can be added at different times. o Imidization After adding the _C1-3 carboxylic acid alkali metal salt and acetic anhydride, the (N _- substituted) maleamic acid-vinyl compound polymer is easily imidized. This imidization is easily carried out without heating the copolymer system, but imidization is promoted by heat treatment. Examples include a method of further heating the copolymer in the polymerization tank after completion of polymerization, a method of heating the recovered copolymer in an organic solvent, and a method of heating the copolymer by passing it through an extruder etc. be done. There is no particular limit to the imidization temperature, but it is 60℃.
It is preferable that it is above. The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Note that parts and % indicate parts by weight and % by weight. Examples 1 to 3 100 parts of methyl ethyl ketone and a predetermined amount of styrene were charged into 10 autoclaves equipped with a turbine type stirrer, and the temperature was maintained at 85°C while t-
Butyl peroxy-2-ethylhexanoate
A solution of 0.5 parts of t-dodecylmercaptan, 0.2 parts of t-dodecylmercaptan, and a predetermined amount of N-phenylmaleamic acid dissolved in 100 parts of methyl ethyl ketone was added continuously over 5 hours. Thereafter, polymerization was carried out at 85°C for 3 hours.
At this time, a solution of sodium acetate and acetic anhydride shown in Table 1 was added before the start of polymerization, and 5 minutes after the start of polymerization.
It was added continuously over time or after the completion of polymerization. After polymerization, the mixture was further heated at 90° C. for 5 hours to imidize N-phenylmaleamic acid. After the reaction, the polymer solution was precipitated in metal to recover the polymer. These results are shown in Table 1.

[Table] Comparative Examples 1 to 2 Polymers were obtained in the same manner as in Example 1, except that acetic anhydride and sodium acetate were not added. The results are shown in Table 1. Example 4 100 parts by weight of a copolymer powder consisting of 35% by weight of N-phenylmaleamic acid, 50% by weight of styrene and 15% by weight of acrylonitrile obtained by a known emulsion polymerization method was placed in a glass flask in Step 3. ,
To this was added 1.5 parts of sodium acetate and 200 parts of acetic anhydride, and the mixture was heated at 85° C. for 7 hours with stirring to imidize. After the reaction, the copolymer was washed with methanol and then dried. As a result, a copolymer with an imidization rate of 97% was obtained. Comparative Example 3 The method of Example 4 was repeated except that no sodium acetate was added. As a result, the imidization rate of the copolymer was only 41%. Example 5 Styrene, acrylonitrile, methyl methacrylate and N-phenylmaleamic acid were polymerized in the presence of polybutadiene (85% gel) based on a known emulsion polymerization method. Salting out - 40% polybutadiene, 15% styrene recovered through drying process,
Acrylonitrile 9%, methyl methacrylate 20%
%, a polymer consisting of 16% N-phenylmaleamic acid (graft polymer particle size 0.4 μ, graft ratio 75
%) Place 100 parts of the powder in a glass flask from Step 3.
2.0 parts of sodium acetate and 200 parts of acetic anhydride were added to this, and the mixture was heated at 85° C. for 7 hours with stirring to imidize. After the reaction, the copolymer was washed with methanol and then dried. As a result, a polymer with an imidization rate of 97% was obtained. Comparative Example 4 The method of Example 5 was repeated except that no sodium acetate was added. As a result, the imidization rate of the polymer was only 39%. Effects of the invention In the copolymerization of (N-substituted) maleamic acid and a vinyl compound, a maleimide copolymer can be obtained with high efficiency by using an alkali metal salt of a _C1-3 carboxylic acid and acetic anhydride _. can.

Claims (1)

[Claims] 1 Maleamic acid and/or N-substituted maleamic acid (a) represented by the following general formula, an aromatic vinyl compound, a vinyl cyanide compound, and an unsaturated carboxylic acid in the presence or absence of rubber. In copolymerization with one or more vinyl compounds (b) selected from the group consisting of alkyl ester compounds, an alkali metal salt of a carboxylic acid having 1 to 3 carbon atoms (c) and acetic anhydride are used before, during or after polymerization. A method for producing a maleimide copolymer, which comprises adding (d) and then imidizing it. (However, R represents hydrogen, an alkyl group, or an aryl group.)