Sumitomo Chemical Company, Limited

Satoshi Shimogama

Masahiko Moritani

Toyomitsu Shimizu

Takashi Kumagai

Disclosed is a process for producing a methacrylate polymer, wherein a monomer feed composed of methyl methacrylate or a mixture of at least 70 weight % of methyl methacrylate and not more than 30 weight % of one or more vinyl monomers copolymerizable with methyl methacrylate is continuously bulk polymerized in a substantially perfect mixing state to give a polymer composition having a polymer content of 40-70% by weight in a continuous manner, which comprises carrying out the bulk polymerization in the reactor which is filled up with the polymer composition leaving substantially no gas phase therein and which is maintained in a thermally insulated state allowing substantially no exchange of heat with the external environment at a polymerization temperature of 120.degree.-180.degree. C. with an average residence time of 15 minutes to 2 hours using a radical initiator having a half-life of not more than 1 minute at the polymerization temperature at a concentration which is equal to C (mol/100 g monomer) satisfying the following relation:

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Niihama, Japan

Satoshi Shimogama