Patent · US Expired

Process for the preparation of high molecular thermoplastic polycarbonates of low flammability

US4098754A · kind A · utility

9Cited by

4References

14Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Dieter Neuray · Krefeld, DE
Hugo Vernaleken · Walsrode, DE
Claus Wulff · Krefeld, DE
Ralf Lange · Krefeld, DE

Key dates

Filing date	Dec 11, 1975
Grant date	Jul 4, 1978
Priority date	—
Expiry date	Dec 11, 1995

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY10S260/24
WIPO fieldMacromolecular chemistry, polymers
WIPO sectorChemistry

Abstract

The present invention is concerned with a process for the production of high molecular weight thermoplastic ppolycarbonates having improved flame resistance and in conjunction with glass fibres, improved mechanical properties and the polycarbonates so produced. A solution polycarbonate is reacted with an alkali metal salt soluble in the melt of the polycarbonate until the Staudinger Index has increased by about 3 to 30 cm.sup.3 /g. This usually requires about 0.0001 to 0.1 wt. % of the salt, based on the weight of polycarbonate and a temperature of about 250.degree. to 400.degree. C for between about 1 and 30 minutes. In a preferred embodiment the reaction is conducted in a self-cleaning twin screw extruder.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.