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:
Jul. 16, 2002
Filed:
Jul. 24, 2001
Patrick Joseph McCloskey, Watervliet, NY (US);
James Day, Scotia, NY (US);
Paul Michael Smigelski, Schenetady, NY (US);
John Lester Maxam, Saratoga Springs, NY (US);
John Aibangbee Osaheni, Clifton Park, NY (US);
General Electric Company, Schenectady, NY (US);
Abstract
Extrusion of a mixture of an ester-substituted diaryl carbonate, such as bis-methyl salicyl carbonate, a dihydroxy aromatic compound such as bisphenol A and a transesterification catalyst such as tetrabutyl phosphonium acetate (TBPA) affords polycarbonate having a weight average molecular weight of greater than 20,000 Daltons. The extruder is equipped with one or more vacuum vents to remove by-product ester-substituted phenol. Similarly, a precursor polycarbonate having ester-substituted phenoxy endgroups, for example methyl salicyl endgroups, when subjected to extrusion affords a polycarbonate having a significantly increased molecular weight relative to the precursor polycarbonate. The reaction to form a higher molecular weight polycarbonate may be catalyzed by residual transesterification catalyst present in the precursor polycarbonate, or by a combination of any residual catalyst and an additional catalyst such as TBPA introduced in the extrusion step. Fries rearrangement products are not observed in the product polycarbonates.