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. 27, 2003
Filed:
Oct. 25, 2001
John Patrick Lemmon, Delanson, NY (US);
Ronald James Wroczynski, Schenectady, NY (US);
Oltea Puica Siclovan, Rexford, NY (US);
General Electric Company, Niskayuna, NY (US);
Abstract
The present invention relates to a synthetic method comprising contacting at least one diaryl carbonate with one or more dihydroxy aromatic compounds in the presence of a transesterification catalyst under melt polymerization conditions to afford a product polycarbonate. The transesterifcation catalysts used according to the method of the present invention are alkali metal salts and alkaline earth metal salts of organic polyacids in combination with tetraalkyl ammonium or tetraalkyl phosphonium compounds which serve as co-catalysts. The transesterification catalysts are derived from polyacids containing both CO H groups and SO H groups and from polyacids containing exclusively CO H groups or exclusively SO H groups. The catalysts employed according to the method of the present invention provide polycarbonates having reduced levels of Fries rearrangement product relative to conventionally employed catalysts such as sodium hydroxide.