Two-stage process for the production of thermoplastic polycarbonate

US5399659A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

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

Key dates

• Filing date: Apr 7, 1994
• Grant date: Mar 21, 1995
• Expiry date: Apr 7, 2014

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G64/307
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The invention relates to a two-stage process for the production of thermoplastic, solvent-free lightly branched polycarbonates in the melt using ammonium and/or phosphonium catalysts in the first stage and alkali metal and/or alkaline earth metal catalysts in the second stage.