Bayer Corporation

Bayer Aktiengesellschaft

Jon M Newcome

Sivaram Krishnan

Ramesh M Pisipati

Jeffrey M Tennant

Wolfgang Ebert

James P Mason

James B Johnson

David M Derikart

Daniel H Bolton

Jeff M Tennant

A thermoplastic molding composition suitable for the preparation of articles having low birefringence is disclosed. Accordingly, the composition contains polycarbonate and a polyester copolymer based on cyclohexane-dimethanol, ethylene glycol and phthalic acid. The invention resides in the findings that the incorporation of a polycarbonate resin having a melt flow index greater than 18 g/10 minutes impart to the composition low birefringence values. The composition is suitable for the preparation of optical storage media, including compact discs.

Compositions having low birefringence

A transparent thermoplastic molding composition having good release properties is disclosed. The composition which contains no magnetic elements contains a polycarbonate resin and 0.01 to 0.3 percent by weight of a mold release agent. The agent is the product of a reaction of a compound represented by formula (I) ##STR1## where R.sub.1 denotes a C.sub.1-30 -alkyl group, with at least one member selected from the group consisting of ##STR2## where R.sub.2 and R.sub.3 independently denote C.sub.1-30 - alkyl or an aryl group, and ##STR3## where n is 1-7.

Polycarbonate compositions having reduced tendency to splay

A thermoplastic molding composition having improved release properties is disclosed. The composition contains a polycarbonate resin and a mold release agent which is a hydroxy ester conforming structurally to ##STR1## where R is a member selected from the group consisting of glycerol, trimethylol propyl and pentaerythritol radicals, R' denotes a C.sub.6-20 hydrocarbon radical having at least one pendant hydroxyl group, and x is 2 to 4.

Polycarbonate compositions having good mold-release properties

Growing community of inventors

Aliquippa, PA, United States of America

Jon M Newcome