JPS626568B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses a monoolefin having 2 to 10 carbon atoms and α.
Regarding a method for producing a copolymer with a β-unsaturated dicarboxylic acid anhydride, more specifically, it suppresses the formation of deposits on the walls of a polymerization tank and efficiently produces a monoolefin copolymer.
The present invention relates to a method for producing an α/β-unsaturated dicarboxylic acid anhydride copolymer. A copolymer obtained by radical copolymerization of a monoolefin such as ethylene, propylene, isobutylene, or styrene and an α/β-unsaturated dicarboxylic acid anhydride such as maleic anhydride or itaconic anhydride is a copolymer of monoolefin itself or its alkali. 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 are likely 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 having atactic polypropylene present 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, isobutene, 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 a monoolefin and an 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 method of the invention requires the use of atactic polypropylene as a dispersant. As this atactic polypropylene, one having a molecular weight of 1,000 to 100,000, which is produced as a by-product during the production of polypropylene (crystalline polypropylene), can be used, but the method for producing it is not limited to the above-mentioned method. The amount of the dispersant used is usually 0.1 to 10 parts by weight, preferably 0.3 to 5 parts by weight, per 100 parts by weight of the α/β-unsaturated dicarboxylic acid anhydride used as the monomer. is less effective in suppressing the formation of deposits, and conversely, if the amount is large, it becomes economically disadvantageous. Further, in the present invention, a solvent that does not dissolve the copolymer 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 peroxypivalate, 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.
An alternating copolymer of about 300 to 50,000 molecules having approximately equimolar amounts is 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. A 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 isobrene, 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. In addition, in the following examples, Bistack-L (manufactured by Chiba Fine Chemical Co., Ltd., Atactic Polypropylene) was used as a dispersant, molecular weight: 5000-15000, softening point: 100-155°C.
was used. Furthermore, all parts and percentages in the examples are by weight. Example 1 196 parts of maleic anhydride and 1.0 part of BISTAC-L as a dispersant were charged into a 3-autoclave equipped with a stirrer, the can was sealed, and the system was then purged with nitrogen and 457 parts of isobutylene and 686 parts of cyclohexane were added under reduced pressure. After adding the mixture and further adding 9.8 parts of t-butyl peroxypivalate, the temperature was raised to 75°C, and the mixture was heated and stirred at the same temperature for 3 hours to carry out a polymerization reaction. 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 was 85.0%, 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 and Vistac L as a dispersant were added in an amount of 0.3 parts, 1.0 parts, 3.0 parts, and 6.0 parts, and charged into a 3-autoclave equipped with a stirrer, sealed, and then the inside of the system was After purging with nitrogen, 1143 parts of a _C5 monoolefin fraction was added under reduced pressure, and 9.8 parts of t-butyl peroxypivalate were further added, the temperature was raised to 75°C, and the mixture was heated and stirred at the same temperature for 3 hours. Polymerization was carried out. After the polymerization reaction was completed, the yield of the produced copolymer was measured, and the formation of deposits on the walls of the polymerization vessel was observed. The results are shown in the table.

[Table] From the results, it can be seen that the examples of the present invention have high yields and are highly effective in suppressing the formation of deposits. 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 70.0%, and no deposits were formed. It was not recognized.

Claims (1)

[Claims] 1. Atactic polypropylene 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 resulting polymer. A method for producing a monoolefin-α/β unsaturated dicarboxylic acid anhydride copolymer, characterized in that the copolymer is made to exist in a polymerization system. 2 Atactic polypropylene has a molecular weight of 1000
~100000 Claim 1
The method described in section. 3. The method according to claim 1, wherein the solvent is an aliphatic hydrocarbon. 4. The method according to claim 1, wherein the α/β-unsaturated dicarboxylic acid anhydride used as the monomer is maleic anhydride. 5. 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.