Bayer Materialscience Ag

Helmut Einberger

Wolfgang Ebert

Alexander Meyer

Wilfried Haese

Uli Franz

Michael Prein

Hermann Kauth

Stephan Konrad

Bert Ruytinx

Stefaan De Vos

Andreas Frankenau

Christian Eh

The present invention provides a polycarbonate resin produced by the continuous interfacial process characterized in that after alkaline hydrolysis with sodium hydroxide, the polycarbonate resin contains an amount of 0.01 to 150 ppm of carbamate compounds according to formula (1) said amount measured by high pressure liquid chromatography, wherein Rand Rindependently of one another denote hydrogen or C-C-alkyl, or together denote C-C-alkylidene, and Rand Rindependently of one another denote hydrogen. C-C-alkyl or phenyl, or together with the carbon atom to which they are bonded form cyclohexyl or trimethylcyclohexyl, the process comprising phosgene reacting with at least one bisphenol at 8 to 17% molar excess of phosgene relative to the bisphenol.

Polycarbonates with good wettability

An improvement to the phase interface process of preparing aromatic polycarbonate is disclosed. The process is characterized in that the phosgenation is carried out at 0 to 40&#xb0; C., and in that the temperature of the reaction mixture at the time of addition of the catalyst at 10 to 40&#xb0; C., and in that the molar ratio of aromatic dihydroxy compounds to phosgene at 1:1.05 to 1:1.20. The polycarbonate thus produced is characterized in its low content of carbamates, making it particularly suitable for the preparation of optical storage media.

Process for the preparation of polycarbonates

Growing community of inventors

Odenthal, Germany

Helmut Einberger