Method for producing polycarbonates

A process for producing polycarbonates by reacting a monomeric carbonate component with at least one diphenol or dialcohol in the presence of a transesterification catalyst, wherein the molten components are mixed with the transesterification catalyst by stirring and a transesterification product is produced, which is polycondensated, characterized in that 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series and having a substantially horizontal driven shaft with stirrers attached thereto, and the polycarbonate being withdrawn from the final reactor, that in its interior each reactor has a ratio of the horizontal length L to the diameter D of 1.2:1 to 10:1, that in the preliminary reactor and in the final reactor a dwell time of the melt of 5 minutes to 30 minutes is maintained, that the temperatures in the preliminary reactor are maintained in the range from 220 to 300° C. and in the final reactor in the range from 240 to 350° C., and that from each reactor vapors are withdrawn, the pressure in the preliminary reactor being maintained in the range from 100 to 900 mbar and in the final reactor in the range from 0.1 to 50 mbar.