06506871 is referenced by 45 patents and cites 3 patents.

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 tetrabutylphosphonium 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.

Title
Extrusion method for making polycarbonate
Application Number
10/167903
Publication Number
6506871 (B1)
Application Date
June 12, 2002
Publication Date
January 14, 2003
Inventor
Mark Howard Giammattei
Selkirk
NY, US
James Day
Scotia
NY, US
Patrick Joseph McCloskey
Watervliet
NY, US
Norberto Silvi
Clifton Park
NY, US
Agent
Noreen C Johnson
US
Andrew J Caruso
US
Assignee
General Electric Company
NY, US
IPC
C08G 64/00
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