Bayer Materialscience Ag

Bayer Intellectual Property Gmbh

Covestro Deutschland Ag

Marc Buts

Johan Vanden Eynde

Pieter Ooms

Andreas Bulan

Johann Rechner

Rainer Weber

Helmut-Werner Heuer

Karl-Heinz Köhler

Melanie Möthrath

Lydia Simon

Rolf Wehrmann

Uwe Hucks

Thomas König

Torsten Hagen

Stephan Konrad

Daniel Koch

Lothar Bunzel

Michael Traving

Thomas Pfingst

Heinrich Hähnsen

Peter Snobl

Frank Guldentops

Karl-Heinz KÖHLER

A process for preparing diaryl carbonate and utilizing at least part of the process wastewater by increasing the concentration of the wastewater phases containing sodium chloride for the electrolysis by means of osmotic membrane distillation with simultaneous dilution of the sodium hydroxide solution obtained from the electrolysis for the diaryl carbonate production process (diphenyl carbonate process) is described.

Process for preparing diaryl carbonate

The invention relates to a polycarbonate composition having reduced subsequent yellowing of the mouldings produced therefrom on heat ageing and having good optical properties of the polycarbonate composition on processing.

Polycarbonate composition having improved heat stability

The invention relates to a process for production of diaryl carbonate combined with the electrolysis of the resultant alkali metal chloride-containing process wastewater. The process according to the invention makes possible, inter alia, improved utilization in electrolysis of the alkali metal chloride-containing solution obtained in the production of diaryl carbonate.

Process for production of diaryl carbonate

A combined process for the preparation of polycarbonate from bisphenols and diaryl carbonates, the monophenol liberated being reacted again for the preparation of the diaryl carbonate and the alkali metal halide forming in the preparation of the diaryl carbonate being converted by electrochemical oxidation, optionally over a gas diffusion electrode, into chlorine and alkali hydroxide solution, the chlorine being recycled into the preparation of the phosgene and the alkali hydroxide solution being recycled into the preparation of the diaryl carbonate.

Process for the preparation of polycarbonate

The invention relates to a polycarbonate composition with improved melt-flowability together with good optical properties and together with good hydrolysis resistance.

Polycarbonate composition with improved melt-flowability

A multi stage process for the production of polycarbonates having low monomer content is disclosed. The process entails, in sequence, (i) transesterifying in the melt at least one dihydroxyaryl compound with at least one diaryl carbonate in the presence of at least one onium catalyst to produce a polycondensate that contains monomers, (ii) introducing into the polycondensate an inhibitor in an hypostoichiometric amount in relation to the catalyst and (iii) reducing in a finishing reactor the content of monomers in said polycondensate. The polycarbonate thus produced is characterized in that it contains less than 350 ppm of diphenyl carbonate, less than 40 ppm of 2,2-bis-(4-hydroxyphenyl)propane and less than 150 ppm of phenol.

Transesterification process for the production of polycarbonates having a low content of volatile compounds

An improvement to the melt transesterification process for the preparation of polycarbonate is disclosed. The improvement entails adding to the process between its medium viscosity reactor and a high viscosity reactor at least one bridged ester of organic sulphur-containing acid.

Inhibition of catalytically active impurities in polycarbonate by the melt transesterification process

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Duffel, Belgium

Marc Buts