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:
Nov. 14, 1995
Filed:
Mar. 11, 1994
Tatsuya Kanno, Hyogo, JP;
Yutaka Fukuda, Hyogo, JP;
Daicel Chemical Industries, Ltd., Osaka, JP;
Abstract
A process for preparing a substantially chloride-ion-free, high-molecular-weight, colorless and transparent polycarbonate by melt-polycondensing a dihydric phenol with a carbonic diester, which comprises using a carbonic diester which is substantially free from (A) phenyl salicylate, o-phenoxybenzoic acid and phenyl o-phenoxybenzoate, (B) tin ion, (C) methyl phenyl carbonate or (D) phenyl salicylate and o-phenoxybenzoic acid. A process for preparing a thermally stable polycarbonate by melt-polycondensing a dihydric phenol with a carbonic diester, which comprises using a borate or, a compound selected from the group consisting of electron-donative amines and salts thereof as a catalyst, and optionally an acidic substance.