JPS631966B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an impact-resistant copolymer,
Specifically, the present invention relates to a method for efficiently producing a rubber-containing styrene-maleic anhydride copolymer with excellent impact resistance and heat resistance through simple operations. Generally, a styrene-maleic anhydride copolymer containing reinforcing rubber is known as a styrene resin with excellent impact resistance and heat resistance. However, the copolymerization reaction between aromatic vinyl compounds such as styrene and maleic anhydride tends to produce alternating copolymers due to the high reactivity of maleic anhydride, and the content of maleic anhydride units has to be kept within a specified amount. It is not possible to produce homogeneous and useful copolymers by conventional methods. Therefore, as a method for producing such a useful copolymer, (1) maleic anhydride is added to styrene in which the rubber is dissolved under stirring at a rate lower than the polymerization rate of styrene, so that the monomeric anhydride is dissolved. (2) Adding acrylonitrile as a third component when copolymerizing styrene and maleic anhydride in the presence of rubber (Japanese Patent Publication No. 55-7849). Method of continuously post-adding maleic anhydride
48213) and (3) ethylene-propylene-
A method is known in which a diene rubber is used and a polar vinyl compound such as acrylonitrile is added to styrene and maleic anhydride for copolymerization in a hydrocarbon solvent (Japanese Unexamined Patent Publication No. 49-28693). However, methods (1) and (2) above have the disadvantage of requiring complicated polymerization control operations such as sequential addition of maleic anhydride, and if the control is incorrect, it may be difficult to obtain a copolymer of satisfactory quality. Moreover, it is difficult to carry out an industrially advantageous continuous polymerization method. Furthermore, since the methods (2) and (3) require a third component such as acrylonitrile, the styrene-maleic anhydride copolymer itself cannot be obtained, but a different type of copolymer is obtained. Therefore, the present inventors have overcome the drawbacks of the above-mentioned conventional techniques and have developed a method for continuously producing a styrene-maleic anhydride copolymer with excellent physical properties, particularly impact resistance and heat resistance, with simple operations. We conducted extensive research to develop this. As a result, if maleic acid half ester is used instead of maleic anhydride and copolymerized with an aromatic vinyl compound such as styrene, then the copolymerized maleic acid half ester unit is dealcoholized and cyclized. It has been found that a copolymer can be obtained. The present invention was completed based on this knowledge. That is, the present invention provides an impact-resistant copolymer characterized in that an aromatic vinyl compound and a maleic acid half ester are copolymerized in the presence of rubber, and then the maleic acid half ester units are dealcoholized and cyclized. The present invention provides a method for manufacturing a combination. The aromatic vinyl compound used in the present invention is
This is the main raw material for the resulting copolymer, and specific examples include styrene-α-methylstyrene, dimethylstyrene, diethylstyrene, monochlorostyrene, dichlorostyrene, vinyltoluene, and mixtures thereof. The maleic acid half ester to be copolymerized with the above-mentioned aromatic vinyl compound is a monoester in which an alcohol having about 1 to 8 carbon atoms is added to maleic anhydride, and usually maleic anhydride and a specified alcohol are mixed in approximately equal moles. Add at a ratio of 1 at below 100℃
It can be obtained by reacting for ~3 hours. Specifically, monomethyl maleate, monoethyl maleate, mono-n-propyl maleate,
Examples include mono-n-butyl maleate. Compared to maleic anhydride, this maleic acid half ester has
Since the copolymerization reactivity with the aromatic vinyl compound is low, the maleic acid content can be kept within the specified amount even if it is added all at once without sequential or divided addition. In the method of the present invention, the ratio of the aromatic vinyl compound and maleic acid half ester to be used is not particularly limited and may be appropriately selected depending on the physical properties of the desired copolymer.
98% by weight of maleic acid half esters, 40-2% by weight of maleic acid half esters, particularly preferably 70-95% by weight of aromatic vinyl compounds and 30-5% by weight of maleic acid half esters. Furthermore, in the method of the present invention, when copolymerizing the above-mentioned aromatic vinyl compound and maleic acid half ester, it is necessary to have rubber present in the reaction system. There are various types of rubber used here, including butadiene rubber, styrene-butadiene rubber, isoprene rubber, butadiene-acrylonitrile rubber, and the like. The amount of this rubber to be used may be determined as appropriate depending on various conditions, but it is usually 2 to 30 parts by weight based on 100 parts by weight of the aromatic vinyl compound and maleic acid half ester.
It may be expressed as a proportion of parts by weight. In the present invention, a vinyl compound can also be added if necessary. Specifically, acrylonitrile, methacrylonitrile, acrylic acid,
Examples include acrylic esters and methacrylic esters. There is no particular restriction on the amount of this vinyl compound used, but usually the total amount of the above aromatic vinyl compound and maleic acid half ester is used.
It may be determined within a range of 40 parts by weight or less per 100 parts by weight. Further, in the method of the present invention, a catalyst or a polymerization regulator can be appropriately added to the reaction system in order to promote the polymerization reaction or adjust the degree of polymerization. Here, a radical generator or the like is usually used as a catalyst.
Specific examples thereof include organic peroxides such as dicumyl peroxide, lauroyl peroxide, and benzoyl peroxide, and azo polymerization initiators such as azobisisobutyronitrile. On the other hand, examples of polymerization initiators include mercaptans. Furthermore, in the method of the present invention, since the reaction proceeds sufficiently by bulk polymerization, a medium such as water or an organic solvent is not necessarily required for the reaction, but it is also possible to add a small amount of solvent or to use solution polymerization. can. The solvent used in this solution polymerization is as follows:
Ketones such as acetone and methyl ethyl ketone,
Aromatics such as toluene and benzene, or cyclohexane are suitable. In the method of the present invention, first, a predetermined amount of an aromatic vinyl compound, rubber, and maleic acid half ester are added to the reaction system in an appropriate order, and if necessary, a vinyl compound, a catalyst, a polymerization regulator, etc. are added. ~
The copolymerization reaction is allowed to proceed at 180°C, preferably from 70 to 160°C. Various types of polymerization are possible, such as bulk polymerization and solution polymerization. Further, it may be carried out either continuously or batchwise. In addition, in the method of the present invention, the entire amount of maleic acid half ester can be added to the reaction system at once. In the conventional method, the reactivity of the maleic anhydride used was too high, and it was not possible to obtain a copolymer with the desired maleic anhydride unit content unless the maleic anhydride units were added sequentially. Since the reactivity of the ester is lower than that of maleic anhydride, it has become possible to produce the desired copolymer even if the entire amount is added at once. Of course, if it is necessary to make the maleic anhydride unit content in the copolymer obtained by the method of the present invention more uniform, the maleic acid half ester can also be added in portions to the reaction system. However, the divided addition in this case is also sufficient for three times or less, which is completely different from the conventional sequential addition. A rubber-modified aromatic vinyl-maleate ester copolymer is obtained by the above reaction, but in the method of the present invention, this copolymer is further processed using a flasher, a thin film evaporator, an extruder, etc. The copolymer is dealcoholized by drying under reduced pressure, heated and melted, and the maleic acid half ester units in the copolymer are cyclized and converted into maleic anhydride units. By such treatment, the desired rubber-modified aromatic vinyl-maleic anhydride copolymer can be efficiently obtained. As described above, in the method of the present invention, the desired copolymer can be obtained even if the entire amount of the reaction raw materials is added at once without adding them sequentially. Therefore, the method is easy to operate and requires simple equipment. This is an extremely industrially advantageous method. In addition, continuous bulk polymerization is possible and there is no polymer precipitation during polymerization.
Manufacturing efficiency is extremely high. Moreover, since the content of maleic anhydride units in the resulting copolymer can be arbitrarily adjusted within the range of 40% by weight or less, it is possible to improve not only impact resistance but also heat resistance or melt flowability depending on the purpose of use. An aromatic vinyl-maleic anhydride copolymer with excellent properties such as the following can be obtained. The copolymer thus obtained can be effectively used as an industrial material, building material or packaging material. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Styrene was placed in a complete mixing reactor with an internal volume of 2.
1240 g, polybutadiene rubber (trade name: 35AS, manufactured by Asahi Kasei Corporation) 89 g, mono-n-butyl maleate 112.7 g, dicumyl peroxide 1.56 g and toluene 220 g were charged, and the reaction was carried out at 117°C for 2 hours. Summer. (Conversion rate 30%). Next, 82.6 g of mono-n-butyl maleate was added to this reaction system, and the reaction was continued for 3 hours (conversion rate 50%). Subsequently, 56.6 g of mono-n-butyl maleate was further added to this reaction system, and the reaction was continued for 3.5 hours. Thereafter, the reaction product was purified by reprecipitation in petroleum ether and dried under reduced pressure to obtain a rubber-modified styrene-mono-n-butyl maleate copolymer. The final conversion rate was 82%. Finally, this copolymer was dealcoholized in a vacuum dryer at 210°C to perform a cyclization reaction to obtain a rubber-modified styrene-maleic anhydride copolymer.
The properties of this product are shown in Table 1. Example 2 Styrene was placed in a complete mixing reactor with an internal volume of 2.
1240 g, polybutadiene rubber (trade name: 35AS, manufactured by Asahi Kasei Corporation) 89 g, mono-n-butyl maleate 248 g, dicumyl peroxide 1.56 g, and toluene 220 g were charged and the reaction was carried out at 117°C for 10 hours. . The reaction product was then purified by reprecipitation in petroleum ether and dried under reduced pressure to obtain a rubber-modified styrene-mono-n-butyl maleate copolymer. The conversion rate was 85%. Finally, this copolymer was heated to 210°C.
A rubber-modified styrene-maleic anhydride copolymer was obtained by dealcoholization and cyclization reaction in a vacuum dryer. The properties of this product are shown in Table 1.

[Table] * Commercially available impact-resistant polystyrene ** Measured at a temperature of 230℃ and a load of 2160g *** Measured at 18.6Kg/cm ²

Claims (1)

[Claims] 1. Impact resistance characterized by copolymerizing an aromatic vinyl compound and a maleic acid half ester in the presence of rubber, and then dealcoholizing and cyclizing the maleic acid half ester unit. Method for producing copolymer. 2 Add the aromatic vinyl compound to the reaction system in a proportion of 60 to 98% by weight and 40 to 2% by weight of the maleic acid half ester, and add rubber to the total amount of the aromatic vinyl compound and maleic acid half ester of 100 parts by weight. 2. The method according to claim 1, wherein 2 to 30 parts by weight are present.