Method for producing branched polycarbonates

US6307006A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Annett Konig · Krefeld, DE
• Lothar Bunzel · Kempen, DE
• Uwe Hucks · Alpen, DE

Key dates

• Filing date: Dec 14, 1999
• Grant date: Oct 23, 2001
• Expiry date: Dec 14, 2019

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G64/30
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process of producing branched polycarbonates by melt transesterification from at least one diphenol, diaryl carbonate and a branching agent, and in the optional presence of a catalyst is disclosed. The process which is carried out at temperatures between 80 to 400.degree. C. and at pressures between 1 and 0.01 mbar, entails using as branching agent at least one member selected from the group consisting of (i) a specifically structured aliphatic alcohol and (ii) the ether of (i) which is formed by self-condensation.