Zimmer Aktiengesellschaft

Rudolf Kaempf

Fritz Wilhelm

Heinz-Dieter Schumann

Klaus Mackensen

Walter Wenzel

Polycarbonates are produced by reacting a monomeric carbonate component with at least one diphenol or dialcohol in the presence of a transesterification catalyst, wherein the molten component is mixed with the transesterification catalyst by stirring and a transesterification product is produced, which is polycondensated. For polycondensation, the transesterification product is passed through a preliminary reactor, at least one intermediate reactor and one final reactor, the reactors being connected in series and having a substantially horizontal driven shaft with stirrers attached thereto. It is ensured that in the preliminary reactor and in the final reactor a dwell time of the melt of 5 minutes to 2 hours is maintained, that the temperatures in the preliminary reactor are maintained in the range from 220 to 300&#xb0; C. and in the final reactor in the range from 240 to 350&#xb0; C., and that the pressure in the preliminary reactor is maintained in the range from 100 to 800 mbar and in the final reactor in the range from 0.1 to 50 mbar.

Method for producing polycarbonates

Process for generating a vacuum and separating the condensable components of the vapors of melt-phase polycondensation in the production of polycarbonate, where at least one or two vapor jets with a downstream spray condenser are connected to the intake side of the polycondensation reactor to be evacuated, and the motive vapor is diphenyl carbonate vapor, and the spray liquid is liquid diphenyl carbonate.

Process for generating a vacuum in production of polycarbonate

A process for the reduction of the carboxyl end groups of linear polyester through reaction with alkylene carbonate in the melt phase in the presence of 40 to 160 ppm of allyltriphenyl phosphonium bromide, based on the weight of the polyester.

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Gruendau, Germany

Rudolf Kaempf