Abstract: 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.

Abstract: 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.

Abstract: A process for the production of high molecular weight aliphatic polycarbonates is disclosed. The process entails a first stage wherein a low molecular weight aliphatic polycarbonate is prepared and a second stage where the low molecular weight aliphatic polycarbonate is condensed with diaryl carbonate in a melt transesterification process to form a high molecular weight aliphatic polycarbonate. The resulting high molecular weight aliphatic polycarbonate is suitable for the production of extrudates, films and molded articles.

Abstract: A process for the preparation of transparent copolycarbonate is disclosed. The copolycarbonate the molecular structure of which contains more than 35 mole % of units derived from dihydroxydiphenylene is prepared by the melt transesterification process wherein the final temperature of the reaction is reached in less than 40 minutes after reaching the starting temperature.

Abstract: The invention relates to a novel polycarbonate and its use a material in the production of molded articles and semifinished products, especially for transparent articles such as data memories or radio compact discs, slabs, cellular sheets, films, housings, panes, especially panes for motor vehicles, diffusion glasses, but also for electrical applications or the constructions of houses.

Abstract: The present invention provides a two-stage process for the production of polyester carbonates with aliphatic dicarboxylic acids, the polyester carbonates obtained thereby, a process for the production of extrudates and molded articles from the polyester carbonates, and the extrudates and molded articles obtained thereby.

Abstract: A process for the production of phosphonium phenolates is disclosed. The process entails reacting a phosphonium halide and phenol in an aqueous alkaline solution.

Abstract: A transesterification process for producing polyester is disclosed. In a first stage of the process there is heated, in an inert gas atmosphere, a first mixture containing at least one dihydroxy compound and at least one diaryl carbonate to form an oligocondensate. In a second stage there is added to the oligocondensate at least one dicarboxylic acid to form a second mixture. The second mixture is heated to a temperature not higher than 290° C. in the presence of a quaternary onium compound as catalyst to form polyester carbonate. Hydroxyaryl formed throughout the process is distilled-off under reduced pressure.

Abstract: A process for producing a high purity tetraphenylphosphonium phenolate that at room temperature is in liquid form is disclosed. The process entails (i) reacting tetraphenylphosphonium halide with phenol in an aqueous-alkaline solution at temperatures of up to 55° C., at a molar ratio of phenol to tetraphenylphosphonium halide ≧10:1 and at pH values of 9.5 to 11 to obtain a material system containing an organic phase and an aqueous phase and, (ii) upon completion of the reaction adding a solution of water and a sparingly soluble alcohol to separate the aqueous phase from the organic phase. The phosphonium phenolate thus produced is suitable as transesterification catalyst, in particular for solvent-free production of thermoplastic polycarbonate.

Abstract: A process for the production of high molecular weight aliphatic polycarbonates is disclosed. The process entails a first stage wherein a low molecular weight aliphatic polycarbonate is prepared and a second stage where the low molecular weight aliphatic polycarbonate is condensed with diaryl carbonate in a melt transesterification process to form a high molecular weight aliphatic polycarbonate. The resulting high molecular weight aliphatic polycarbonate is suitable for the production of extrudates, films and molded articles.

Abstract: The present invention provides a two-stage process for the production of polyester carbonates with aliphatic dicarboxylic acids, the polyester carbonates obtained thereby, a process for the production of extrudates and molded articles from the polyester carbonates, and the extrudates and molded articles obtained thereby.

Abstract: A process for the synthesis of polycarbonate is disclosed. The process entails reacting in the presence of at least one phosphonium salt as catalyst, at least one diphenol, at least one carbonic acid diester, and at least one alkyl group-substituted phenol chain terminator. The chain terminator is introduced in free form or as a transesterifiable compound under the conditions of the synthesis. The polycarbonate thus produced is suitable for preparing a variety of molded articles.

Abstract: A transesterification process for producing polyester is disclosed. In a first stage of the process there is heated, in an inert gas atmosphere, a first mixture containing at least one dihydroxy compound and at least one diaryl carbonate to form an oligocondensate. In a second stage there is added to the oligocondensate at least one dicarboxylic acid to form a second mixture. The second mixture is heated to a temperature not higher than 290° C. in the presence of a quaternary onium compound as catalyst to form polyester carbonate. Hydroxyaryl formed throughout the process is distilled-off under reduced pressure.

Abstract: A process for determining the suitability of a specific raw material entailed in the melt transesterification of polycarbonate is disclosed. The process entails melting the raw materials including the specific raw material in a reaction vessel and measuring the elapsed time until formation of the first drop of the hydroxyl compound.

Abstract: A process for the preparation of transparent copolycarbonate is disclosed. The copolycarbonate the molecular structure of which contains more than 35 mole % of units derived from dihydroxydiphenylene is prepared by the melt transesterification process wherein the final temperature of the reaction is reached in less than 40 minutes after reaching the starting temperature.

Abstract: The invention relates to a method for producing phosphonium phenolates from phosphonium halogenides and phenols.

Abstract: A process for preparing phosphonium phenolate is disclosed. The process entails a reaction of phosphonium halide with phenol in an aqueous alkaline solution at a temperature of 0 to 55° C. The molar ratio of phenol to phosphonium halide is between 2:1 to 10:1 and the pH of the solution is 9.5 to 11. An optional embodiment entails carrying out the reaction in the further presence of alcohol.

Abstract: A process of producing branched polycarbonates by melt transesterification from at least one diphenol, diaryl carbonate and a branching agent, and in the optional presence of a catalyst is disclosed. The process which is carried out at temperatures between 80 to 400° C. and at pressures between 1 and 0.01 mbar, entails using as branching agent at least one member selected from the group consisting of (i) a specifically structured aliphatic alcohol and (ii) the ether of (i) which is formed by self-condensation.

Abstract: A process for preparing phosphonium phenolate is disclosed. The process entails a reaction of phosphonium halide with phenol in an aqueous alkaline solution at a temperature of 0 to 55° C. The molar ratio of phenol to phosphonium halide is between 2:1 to 10:1 and the pH of the solution is 9.5 to 11. An optional embodiment entails carrying out the reaction in the further presence of alcohol.