Preparation of branched polycarbonate from oligomeric cyclic polycarbonate and polyhydric phenol

Abstract

Branched polycarbonates are prepared by melt equilibration of aromatic cyclic polycarbonate oligomers with a polyhydric phenol having more than two hydroxy groups per molecule, preferably 1,1,1-tris-(4-hydroxyphenyl)ethane, in the presence of a carbonate equilibration catalyst, preferably tetrabutylammonium tetraphenylborate. In an additional embodimetn of the invention, a linear aromatic polycarbonate is added to the reaction mixture. Branched polycarbonates prepared according to this inventin have high melt strength and high shear sensitivity characteristics and are useful in extrusion and injection molding processing applications and particularly useful in blow molding applications for preparing relatively large articles and panels.

Dependencies are inferred from the claim text.