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:
Oct. 21, 2003
Filed:
Dec. 10, 1998
Kiyoshi Kono, Ichihara, JP;
Kazutoyo Uno, Chiba, JP;
Satoru Minami, Ichihara, JP;
Tomoaki Shimoda, Ichihara, JP;
General Electric Company, Schenectady, NY (US);
Abstract
A method for manufacturing polycarbonate by melt-polycondensing bisphenol and carbonic acid diester uses as catalyst an alkali metal compound and/or alkaline earth metal compound (a). The catalyst is added to the bisphenol prior to the melt polycondensation, in an effective amount, i.e., the amount of alkali metal compound and/or alkaline earth metal compound (a) that acts effectively as a catalyst, is contained in said bisphenol, and is controlled to have the same catalytic activity as 1×10 to 1×10 mole of bisphenol disodium salt per mole of pure bisphenol A. The method conducts the reaction efficiently from the initial stage in a stable manner to obtain polycarbonate with good color, good heat stability and color stability during molding and the like.