Improved transesterification process for the production of polycarbonates

US5444148A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Wolfgang Alewelt · Krefeld, DE
• Steffen Kuhling · Meerbusch, DE
• Hermann Kauth · Krefeld, DE

Key dates

• Filing date: Nov 19, 1993
• Grant date: Aug 22, 1995
• Expiry date: Nov 19, 2013

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P20/582
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

An improvement to the transesterification process for the production of aromatic polycarbonates is disclosed. Into the melt which contains diphenols, carbonic acid diaryl esters and optionally branching agents and at temperatures of 130.degree. C. to 400.degree. C. and in the presence of catalysts there is mixed or passing thereover inert gas in a quantity of at least 0.5 Nm3 per kg of polycarbonate melt.