Process for producing oligocarbonates

US6835797B2 · kind B2 · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Uwe Hucks · Alpen, DE
• Rolf Bachmann · Busswil, CH
• Franz Ferdinand Rhiel · Dormagen, DE
• Thomas Fischer · Graz, AT
• Silke Kratschmer · Krefeld, DE

Key dates

• Filing date: Mar 22, 2002
• Grant date: Dec 28, 2004
• Expiry date: Sep 9, 2022

Classification

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

Abstract

A continuous process for producing oligocarbonate is disclosed. The process entails in sequence the steps of a) reacting a dihydroxyaryl compound with a diaryl carbonate in the presence of a catalyst to obtain a melt and avoiding removal of released monohydroxyaryl compound and b) withdrawing the monohydroxyaryl compound by flash evaporation and c) heating the melt obtained under vacuum in an evaporator equipped with sump receiver and d) repeating at least once steps b) and then c) each at gradually increased temperatures and lowered pressures.