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Bayer Aktiengesellschaft

Bayer Antwerpen N.v.

Dirk Van Meirvenne

Franky Bruynseels

Steffen K&uuml;hling

Michael B&ouml;diger

Steffen Kühling

René De Cleyn

Ren&eacute; De Cleyn

Friedrich-Karl Bruder

Wilfried Haese

Wolfgang Alewelt

Johan Vanden Eynde

Thomas Bieringer

Michael Bödiger

Ren&euml; De Cleyn

A process for the preparation of optical data carriers made of a particualr polycarbonate is disclosed. The polycarbonate is prepared by the phase boundary process that entails reacting at least one dihydroxydiarylalkane in the form of its alkali metal salts with phosgene in the heterogeneous phase in the presence of sodium hydroxide solution and an organic solvent. The process is characterized in that the feedstock have but low content of Fe, Cr, Ni, Zn, Ca, Mg, Al metals or homologues thereof, and in that the organic solvent is separated off, and in that the polycarbonate which is obtained is worked up. The resulting polycarbonate is particularly useful in producing optical data carriers.

Optical data carriers and method for producing the same

Polycarbonate substrates, the preparation of which is based on 1,1-bis-(4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, and their use for producing shaped articles with particularly high purity and extremely high surface brilliance and also the shaped articles which can be produced from the polycarbonate substrate are described.

Polycarbonate substrates

A process for the preparation of polycarbonate by the phase boundary process is disclosed. The process entails reacting at least one dihydroxydiarylalkane in the form of its alkali metal salts with phosgene in the heterogeneous phase in the presence of sodium hydroxide solution and an organic solvent. The process is characterized in that the feedstock have but low content of Fe, Cr, Ni, Zn, Ca, Mg, Al metals or homologues thereof, and in that the organic solvent is separated off, and in that the polycarbonate which is obtained is worked up. The resulting polycarbonate is particularly useful in producing transparent shaped articles.

Method of producing polycarbonates

Polycarbonate substrates having low concentration of defects are disclosed. The substrates are suitable for producing molded articles characterized by low cloudiness.

Polycarbonate substrates, the preparation of which is based on 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexanone, and their use for producing shaped articles with particularly high purity and extremely high surface brilliance and also the shaped articles which can be produced from the polycarbonate substrate are described.

An improvement to the interfacial boundary process for continuous production of carbonic acid diaryl esters is disclosed. The process that entails a reaction of monophenols in an inert solvent, in the presence of an alkaline solution and a nitrogen base catalyst, is carried out in two stages. In the first stage phosgene, inert solvent and phenol in solution are combined to form a material system and a second stage the reaction to form carbonic acid diaryl ester is completed. The improvement comprising maintaining in the first stage a pH of 11.0 to 12.0 and a temperature below 40&deg; C. and a pH of 7.5-10.5 and a temperature <50&deg; C. in the second stage.

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Chonburi, Thailand

Dirk Van Meirvenne