JPS626567B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses a monoolefin having 2 to 10 carbon atoms and α.
Regarding the method for producing a copolymer with β-unsaturated dicarboxylic acid anhydride, in more detail, the production of a copolymer with monoolefin-α
The present invention relates to a method for producing a β-unsaturated dicarboxylic anhydride copolymer. Copolymers obtained by radical copolymerization of monoolefins such as ethylene, propylene, isobutylene, and styrene with α/β-unsaturated dicarboxylic acid anhydrides such as maleic anhydride and itaconic anhydride can be obtained by the radical copolymerization of monoolefins such as ethylene, propylene, isobutylene, and styrene. Dispersants for dyes and pigments in the form of metal salts, ammonium salts, esters, etc., cement admixtures, gypsum dispersants, mud admixtures, floor polishing agents, adhesives, paints, viscosity index improvers, pour point depressants, etc. It is known that it can be used in the fields of These copolymers are generally obtained by carrying out polymerization in a solution or suspension state in a reaction-inert solvent such as ketones, aromatic hydrocarbons, aliphatic hydrocarbons, etc. When polymerization is carried out in a suspended state, deposits tend to form on the inner wall of the polymerization vessel and the stirring blade during polymerization, which not only reduces the yield of the copolymer but also reduces the thermal efficiency of the reaction system. It is also a cause of deterioration in quality. This tendency is particularly noticeable when aliphatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, etc. are used, and is a major obstacle to improving productivity. Therefore, attempts have been made to adjust the particle size of the produced polymer by using dispersants and to suppress the formation of deposits on the walls of the polymerization tank. A method using an equimolar copolymer of 14 to 18 α-olefins and maleic anhydride (US Pat. No. 3,729,451),
- A method using a half-ester or half-amide of a copolymer of olefin and maleic anhydride (JP-A-Sho
No. 51-95489) are known, but the development of even more dispersants was expected. An object of the present invention is to provide a method for efficiently producing a monoolefin-α/β-unsaturated dicarboxylic acid anhydride copolymer by suppressing the formation of deposits on the inner wall of a polymerization vessel, a stirrer, etc. The object of the present invention is to use a monoolefin having 2 to 10 carbon atoms and an α/β-unsaturated dicarboxylic acid anhydride as a dispersant when radically copolymerizing them in a solvent that does not dissolve the resulting polymer. This is achieved by allowing the ethylene-vinyl ester copolymer to exist in the polymerization system. The monomers used in the present invention are monoolefins and α/β-unsaturated dicarboxylic acid anhydrides. Specific examples of monoolefins include ethylene, propylene, isoptene, butene-1, butene-2, pentene-1, pentene-2, 2-methylbutene-1, 2-methylbutene-2, hexene-1, 2. 2,4-trimethylpentene-1,
2,2,4-trimethylpentene-2, decene-
Examples include chain monoolefins such as 1, cyclic monoolefins such as cyclopentene, cyclohexene, and cyclooctene, and aromatic monoolefins such as styrene, α-methylstyrene, and vinyltoluene. No. 6 chain monoolefin is used. In addition, a distillate whose main components are paraffins and monoolefins after separating conjugated diolefins such as butadiene, isoprene, and cyclopentadiene from the C ₄ fraction and C ₅ fraction obtained by naphtha decomposition etc. may be used. However, in this case, the formation of deposits is particularly severe due to the influence of a small amount of remaining conjugated diolefin, so the effect produced by the present invention is even greater. On the other hand, the α/β-unsaturated dicarboxylic acid anhydride may be any one commonly used in this technical field, and specific examples thereof include maleic anhydride, itaconic anhydride, citraconic anhydride, etc. Examples include those having 4 to 10 carbon atoms. Among these, maleic anhydride is prized for its reactivity, quality, and economy. Polymerization of monoolefin and α/β-unsaturated dicarboxylic acid anhydride is carried out according to a conventional method in a solvent that does not dissolve the resulting polymer, but at this time, a specific dispersant is present in the polymerization system. It is necessary to encourage them. The dispersant used has a vinyl ester content of 5% by weight or more, preferably 10 to 50% by weight, and a melt index (MI, ASTM D-1238) of 5.
g/10min or more, preferably 10-1000g/10min
It is an ethylene-vinyl ester copolymer. Vinyl ester, which is a monomer component of this ethylene-vinyl ester copolymer, is a vinyl ester of a carboxylic acid having an alkyl group having 1 to 4 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl valerate. It is an ester, especially vinyl acetate. The amount of dispersant used is
It is usually 0.1 to 10 parts by weight, preferably 0.3 to 5 parts by weight, per 100 parts by weight of α/β-unsaturated dicarboxylic acid anhydride used as a monomer, and if the amount used is small, the formation of deposits is suppressed. If the effect is small, and if there is too much, it will be economically disadvantageous. Further, in the present invention, a solvent that does not dissolve the copolymer to be produced is used as a polymerization solvent. Specific examples of such solvents include linear, branched or cyclic aliphatic hydrocarbons such as butane, pentane, hexane, heptane, ligroin, cyclohexane, etc., aromatic hydrocarbons such as benzene, toluene, xylene, etc. Examples include hydrogen, and aliphatic hydrocarbons, particularly aliphatic hydrocarbons having 4 to 6 carbon atoms, are preferred from the viewpoint of safety, ease of separation, and economic efficiency. Moreover, it is also possible to make the monoolefin used as a monomer exist in excess and use it as a polymerization solvent. In the present invention, polymerization is carried out according to a conventional method in the presence of the above-mentioned solvent and dispersant.
Catalysts used in the reaction include organic peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, diisopropyl peroxydicarbonate, t-butyl peroxybivalate, etc., α・α′- Azobisisobutyronitrile, α・α′-azo-α-
A radical initiator such as an azobis compound such as ethylbutyronitrile, a redox catalyst, etc., and is not particularly limited as long as it is a radical initiator. The amount of such a catalyst used is usually 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the α/β-unsaturated dicarboxylic anhydride. Polymerization is usually carried out at 5 to 150°C, preferably 20 to 120°C.
It is carried out in suspension for 0.5 to 12 hours.
At this time, when using a solvent that does not dissolve α/β-unsaturated dicarboxylic acid anhydride,
It is necessary to polymerize at a temperature higher than the melting point of the α/β-unsaturated dicarboxylic acid anhydride, and it is particularly preferable to polymerize at a temperature higher than the melting point of the dispersant. The charging ratio of monoolefin and α/β-unsaturated dicarboxylic acid anhydride can be selected arbitrarily, but from the viewpoint of reactivity, the amount of monoolefin should be set at 80%.
~40 mol%, preferably 70-50 mol% is suitable. Further, in order to increase productivity, it is preferable to make the monomer concentration as high as possible, and it is appropriate to polymerize at a monomer concentration of 10% by weight or more, more preferably 20% by weight or more. After the polymerization is completed, the produced polymer is separated from the solvent according to a conventional method, and the number average molecular weight is determined.
Approximately equimolar alternating copolymers of about 300 to 50,000 are obtained. According to the present invention, since almost no deposits are observed on the inner walls of the polymerization can or the stirrer, stable operation is possible without cleaning the polymerization can over a long period of time, resulting in high yields. The copolymer can be obtained efficiently at a high rate. Next, the present invention will be explained in more detail with reference to Examples. The _C5 monoolefin fraction used in the examples refers to pentene-1 and pentene-1 obtained by separating conjugated diolefins such as isoprene, 1,3-pentadiene, and cyclopentadiene from the _C5 fraction.
Approximately 40% by weight of monoolefin containing 2,2-methylbutene-1 and 2-methylbutene-2 as main components,
It means a mixture consisting of about 1% by weight of conjugated diolefin mainly composed of 1,3-butadiene, isoprene, 1,3-pentadiene and cyclopentadiene, and about 59% by weight of paraffin mainly composed of n-pentane. In addition, the numerical values indicating the formation status of deposits in Examples and Comparative Examples refer to the state without deposits.
The evaluation was divided into five stages from (1) to (5) where a large amount of deposits were observed. Table 1 also shows the types of ethylene-vinyl ester copolymers used in the following examples.

[Table] Furthermore, all parts and percentages in the examples are based on weight. Example 1 196 parts of maleic anhydride and 1.0 part of the ethylene-vinyl acetate copolymer () shown in Table 1 as a dispersant were charged into a 3-autoclave equipped with a stirrer, the autoclave was sealed, and the system was replaced with nitrogen. A mixture of 457 parts of isobutylene and 686 parts of cyclohexane was added under reduced pressure, and further 9.8 parts of t-butyl peroxypivalate was added.
After adding 50% of the mixture, the temperature was raised to 75°C, and the polymerization reaction was carried out by heating and stirring at the same temperature for 3 hours. The condition inside the autoclave after the completion of the polymerization reaction was at stage (1), with almost no deposits observed on the inner walls or stirring blades. The conversion rate of maleic anhydride in this reaction is
The yield was 82.0%, and since no deposits were formed, the yield based on maleic anhydride was also approximately the same. Comparative Example 1 Polymerization was carried out according to Example 1 except that no dispersant was used, and the conversion rate of maleic anhydride was 43.8%, but the amount of deposits formed was extremely large (5). Because of the heat, the desired copolymer could hardly be obtained. Example 2 196 parts of maleic anhydride, ethylene-vinyl acetate copolymer () shown in Table 1 as a dispersant
1.0 part of () was charged into a 3-autoclave equipped with a stirrer, the can was sealed, and the inside of the system was purged with nitrogen. 1143 parts of _C5 monoolefin fraction was added under reduced pressure, and an additional 9.8 parts of t-butylperoxypivalate was added. After adding 50% of the mixture, the temperature was raised to 75°C, and the mixture was heated and stirred at the same temperature for 3 hours to effect polymerization. After the polymerization reaction was completed, the yield of the produced copolymer was measured, and the state of deposits on the walls of the polymerization vessel was observed. The results are shown in Table 2.

[Table] From the results, it can be seen that in the case of the examples of the present invention, the yield was high and, moreover, the formation of deposits was hardly observed. Example 3 An experiment was carried out in the same manner as in Example 1, except that 555 parts of cyclopentene was used in place of the isobutylene used in Example 1. The conversion rate of maleic anhydride was 72.0%, and no deposits were formed. It was not recognized.

Claims (1)

[Scope of Claims] 1. Ethylene-vinyl ester is used as a dispersant when radical copolymerizing a monoolefin having 2 to 10 carbon atoms and an α/β-unsaturated dicarboxylic acid anhydride in a solvent that does not dissolve the produced polymer. A method for producing a monoolefin-α/β unsaturated dicarboxylic acid anhydride copolymer, which comprises causing the copolymer to exist in a polymerization system. 2. The ethylene-vinyl ester copolymer has a vinyl ester content of 5 to 50% by weight and a melt index (MI) of 5 to 1000 g/10 min.
The manufacturing method according to claim 1. 3. The manufacturing method according to claim 2, wherein the ethylene-vinyl ester copolymer is an ethylene-vinyl acetate copolymer. 4. The manufacturing method according to claim 1, wherein the solvent is an aliphatic hydrocarbon. 5. The method according to claim 1, wherein the α/β-unsaturated dicarboxylic acid anhydride used as the monomer is maleic anhydride. 6. The method according to claim 1, wherein the amount of the dispersant used is 0.1 to 10 parts by weight per 100 parts by weight of the α/β-unsaturated dicarboxylic anhydride.