Abstract: A process for producing optical fibers is disclosed. The fibers that are characterized in having a core that contain an amorphous transparent thermoplastic polymer are prepared by a process entailing melting the polymer in an apparatus the surfaces of which that come into contact with the molten polymer are first rendered at least partially inert.

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: The present invention relates to a process for working up solutions of polymers in organic solvents contaminated by alkaline constituents, using homogeneously soluble acids, especially by the introduction of an acid gas, and subsequent washing, and to the polymers so obtainable, which are distinguished by the fact that, on treatment with moist heat (sterilisation), only few defects caused by decomposition are formed, to the use thereof in the production of extrudates and molded specimen, and to the extrudates and molded specimen produced from those polymers themselves.

Abstract: 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° C. and a pH of 7.5-10.5 and a temperature <50° C. in the second stage.

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 branched polycarbonate resin suitable for making containers is disclosed. The polycarbonate is characterized in that at 260° C. and shear rate of 10 s−1 it has a melt viscosity of 5500 to 900 Pas, and in that at 260° C. and shear rate of 1000 s−1 it has a melt viscosity of 880 tom 1500 Pas, and in that it has a melt flow index (MFR) of 0.1 to 3.0 g/10 min. A container made of the polycarbonate exhibits great breaking strength.

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 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: An improvement to the interfacial boundary process for producing carbonic acid diaryl esters is disclosed. In the two-stage process that entails phosgene and monophenols reaction in an inert solvent, in the presence of alkali and in the presence of a nitrogen base catalyst, the improvement comprising maintaining a temperature below 50° C. in the first and second stages.

Abstract: The present invention relates to a process for working up solutions of polymers in organic solvents contaminated by alkaline constituents, using homogeneously soluble acids, especially by the introduction of an acid gas, and subsequent washing, and to the polymers so obtainable, which are distinguished by the fact that, on treatment with moist heat (sterilisation), only few defects caused by decomposition are formed, to the use thereof in the production of extrudates and molded specimen, and to the extrudates and molded specimen produced from those polymers themselves

Abstract: 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° C. and a pH of 7.5-10.5 and a temperature below <50° C. in the second stage.

Abstract: An improvement to the interfacial boundary process for producing carbonic acid diaryl esters is disclosed. In the two-stage process that entails phosgene and monophenols reaction in an inert solvent, in the presence of alkali and in the presence of a nitrogen base catalyst, the improvement comprising maintaining a temperature below 50° C. in the first and second stages.

Abstract: An improvement to the transesterification process for the production of aromatic polycarbonates is disclosed. Into the melt which contains diphenols, carbonic acid diaryl esters and optionally branching agents and at temperatures of 130.degree. C. to 400.degree. C. and in the presence of catalysts there is mixed or passing thereover inert gas in a quantity of at least 0.5 Nm3 per kg of polycarbonate melt.

Abstract: The present invention provides a transesterification process for the production of thermoplastic, solvent-free polycarbonates by the use of catalysts that are derived from guanidine.

Abstract: The invention relates to a two-stage process for the production of thermoplastic, solvent-free lightly branched polycarbonates in the melt using ammonium and/or phosphonium catalysts in the first stage and alkali metal and/or alkaline earth metal catalysts in the second stage.

Abstract: A process for the production of polycarbonates is disclosed. Accordingly, oligocarbonate in the melt is passed through a heated tube and inert gas is simultaneously introduced by injecting to the melt.

Abstract: A process for the production of polycarbonates by melt transesterification is disclosed. Accordingly, polycarbonate waste is dissolved in monophenols and at an elevated temperature and in the presence of a catalyst degraded to yield oligocarbonates, diaryl carbonates and diphenols. Following the optional separation of fillers and other additives there is produced by partial recondensation and the distillation of monophenol a higher viscosity oligocarbonate having a OH and aryl carbonate terminal groups and a weight average molecular weight of 8000 to 18000, the oligocarbonate thus produced is then polycondensed to form a polycarbonate resin.

Abstract: A two step solvent-free process for the preparation of polycarbonates having a low degree of branching is disclosed. Accordingly, the process comprise(i) transesterifying in the melt, at temperatures of from 80.degree. to 250.degree. C. and under atmospheric pressure and for a time of up to five hours of diphenols and carbonic acid diaryl esters in the presence of a catalyst to form an oligocarbonate having a weight average molecular weight of from 8,000 to 18,000 and an OH-end group content of from 25 to 50%, and(ii) polycondensing of said oligocarbonate at temperatures of from 250.degree. C. to 295.degree. C. and pressures of from <500 mbar to 0. 01 mbar,said catalyst being present in an amount of 10.sup.-1 to 10.sup.-8 tool of a catalyst per tool of diphenol, said catalyst being at least one member selected from the group consisting of quaternary ammonium compounds and quaternary phosphonium compounds.

Abstract: The present invention relates to a process for isolating polycarbonates in which a solution of polycarbonate in an organic solvent is dispersed with steam and which is characterized in that the resulting suspension of polycarbonate particles, condensed water and water/solvent vapor is subsequently dried in a tube with cross-sectional constrictions.

Abstract: The object of the present invention is to provide a process for the preparation of aromatic polycarbonates in the molten state using fluoride catalysts.