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:
May. 21, 1996
Filed:
Jan. 17, 1995
Masahiro Nukui, Machida, JP;
Takao Tayama, Machida, JP;
Takeshi Kashiwagi, Yokohama, JP;
Masatoshi Kimura, Yokohama, JP;
Hidekazu Shoji, Yokohama, JP;
Mitsubishi Chemical Corporation, Tokyo, JP;
Abstract
A process for preparing an aromatic polycarbonate resin from an aromatic dihydroxy compound and a carbonate diester by transesterification in the presence of a transesterification catalyst comprising; reacting a purified carbonate diester with an aromatic dihydroxy compound in the presence of a transesterification catalyst to form a polycarbonate prepolymer; said carbonate diester containing benzophenone and benzoate ester derivatives having a molecular weight of less than 1,000, each in an amount of 100 ppm or less, said polycarbonate prepolymer having a viscosity average molecular weight of 5,000 to 20,000 at a temperature of 140.degree. to 280.degree. C., the reaction pressure being from 0.1 Torr to normal pressure; polymerizing said prepolymer at a temperature of 240.degree. to 350.degree. C. in a lateral, bi-axial, self-cleaning reactor to obtain an aromatic polycarbonate resin having a viscosity average molecular weight of 15,000 to 60,000. The aromatic polycarbonate is colorless and transparent and is suitable for extrusion molding.