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:
Sep. 28, 2004
Filed:
Oct. 07, 2002
Patrick Joseph McCloskey, Watervliet, NY (US);
Warren William Reilly, Northville, NY (US);
General Electric Company, Niskayuna, NY (US);
Abstract
The present invention provides a method of preparing polycarbonate, said method comprising (A) oligomerising in the presence of a catalyst at least one dihydroxyaromatic compound at a temperature in a range between about 220-280° C. and a pressure in a range between 180 mbar and 20 mbar, said catalyst comprising a tetraarylphosphonium compound and optionally a co-catalyst, to provide an oligomeric polycarbonate having a number average molecular weight, Mn, in a range between about 1000 and about 6000 daltons; and (B) in a second step heating the oligomeric polycarbonate formed in step (A) at a temperature range between about 280 and about 310° C. and a pressure in a range between about 15 mbar and about 0.1 mbar, to provide a polycarbonate having a weight average molecular weight, in a range between about 15,000 and about 50,000 daltons, said product polycarbonate comprising less than 1000 parts per million Fries product.