Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1988-05-27
1990-04-10
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526 81, 526262, 526342, 526347, C08F 218
Patent
active
049161962
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for producing a heat resistant resin composition. More particularly, it relates to a process for producing a heat resistant resin composition having residues of a maleimide monomer in the molecular chains and being capable of providing a molded product having excellent transparency and mechanical strength.
For the production of styrene-type heat resistant resins having high heat distortion tempertures, a number of proposals have been made for producing copolymers comprising a styrene monomer, a maleimide monomer and a vinyl monomer copolymerizable therewith.
In general, in the copolymerization reaction of a styrene monomer with a maleimide monomer, an alternating copolymer is likely to form even when the proportion of the maleimide monomer is small, and the maleimide monomer tends to be consumed first. If the polymerization is continued further, a polymer containing a large amount of the styrene monomer will form. In such a case, the copolymer containing a large amount of the maleimide monomer formed during the earlier stage of the polymerization and the polymer of the styrene monomer formed during the later stage of the polymerization are usually poor in the compatibility to each other, and it has been difficult to obtain a resin composition capable of providing a molded product having excellent heat resistance and mechanical properties. Therefore, in order to obtain a copolymer having a uniform composition, it is necessary to conduct the polymerization reaction while continuously adding the maleimide monomer. On the other hand, if the maleimide monomer content in the formed copolymer is large, the copolymer is likely to precipitate from the styrene monomer solution, and it is impossible to conduct the polymerization reaction in a homogeneous system. In such a case, it is common to use a solvent. However, if a solvent is used, it is necessary to remove it from the polymerization system, and such is not industrially advantageous.
As a method for solving such problems, it has been proposed to conduct the copolymerization of the styrene monomer with the maleimide monomer in the presence of a vinyl cyanide monomer and conducting the polymerization reaction by adjusting the mixing proportions of the monomers to certain specific ranges, whereby a resin composition having high heat resistance with good compatibility can be obtained (Japanese Unexamined Patent Publication No. 79019/1985).
However, the method disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 79019/1985 had drawbacks such that when the polymerization reaction was conducted by suspension polymerization, the suspension stability was inadequate, and the suspension system tended to be unstable whereby the polymerization reaction product tended to agglomerate, or if the suspension state was maintained, the suspending agent was likely to be included in the resulting resin composition and if such a resin composition was used as a material for a molded product, the transparency of the molded product tended to be poor. Thus, it was necessary to improve the disclosed method.
The present inventors have conducted extensive research to overcome the above drawbacks and to provide an industrially advantageous process for producing a maleimide copolymer resin composition having particularly excellent transparency in addition to excellent heat resistance and strength, and as a result, have found it possible to obtain a resin composition having the desired quality by separately adding a monomer mixture having certain specific proportions of monomers and a suspending agent to the polymerization system. The present invention has been accomplished on the basis of this discovery.
The present invention provides a process for producing a heat resistant resin composition, which comprises polymerizing by suspension polymerization a monomer mixture comprising from 30 to 80% by weight of an aromatic vinyl monomer, from 10 to 50% by weight of an N-substituted maleimide monomer, from 10 to 40% by weight of a v
REFERENCES:
Chemical Abstracts, vol. 101, No. 22, 26-Nov.-1984, (Columbus, Ohio, U.S.A.), see p. 38, abstract 193041z, & JP A, 59135210 (Denki Kagaku Kogyo K.K.), Aug 3, 1984.
Chemical Abstracts, vol. 100, No. 14, 2-Apr.-1984, (Columbus, Ohio, U.S.A.), see p. 13, abstract 104081b, & JP A, 58162616 (Toray Industries, Inc.), Sep. 27, 1983.
Aoki Yuji
Miyazaki Hiroaki
Mitsubishi Monsanto Chemical Company
Schofer Joseph L.
Walker Alex H.
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