The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 29, 1992
Filed:
Aug. 12, 1991
Hiroyuki Ikeda, Toyama, JP;
Michitoshi Shinka, Toyama, JP;
Suehiro Tayama, Otake, JP;
Tetuya Sawano, Otake, JP;
Masahiro Saruta, Otake, JP;
Mitsubishi Rayon Co., Ltd., , JP;
Abstract
A monomer comprising methyl methacrylate either alone or in combination with another acrylic or methacrylic ester monomer is partially polymerized to prepare a syrup, to which an initiator including a peroxide having a 10-hour half-life temperature of 50.degree. to 58.degree. C. and 2,2'-azobisisobutyronitrile are added. The resulting syrup, after being poured into a mold, is initially polymerized in a first step at a temperature of 75.degree. to 90.degree. C. for a period of 5 to 15 minutes, then further polymerized in a second step at a temperature 3.degree. to 12.degree. C. lower than the temperature of the first step polymerization until a conversion of monomer to polymer of 80 to 95% is attained. The polymerization product which is now in the form of a sheet is then heat-treated at a temperature of 95.degree. to 140.degree. C. to obtain a methacrylic resin sheet. According to this process, methacrylic resin sheets having little residual monomer and being substantially free of defects can be manufactured with high productivity.