Abstract: The invention relates to polycarbonates with extremely low residual levels of volatile constituents and thermal degradation products, and also improved optical properties, especially Yellowness Index (YI) and good thermal stability, from solvent-containing polymer melts. The invention further relates to an apparatus and a process for preparing these polycarbonates with the aid of a devolatilizing extruder with at least three devolatilizing zones, and zones for introducing entraining agent into dispersion are present upstream of at least three devolatilizing zones.

Abstract: 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.

Abstract: The present invention relates to a process for continuously preparing diaryl carbonates from dialkyl carbonates and at least one monohydroxyl compound in the presence of catalysts, and to the use thereof for preparation of polycarbonates. The alkylene glycol obtained in the preparation of the dialkyl carbonate used is recycled by oxidative carbonylation with carbon monoxide in the presence of a catalyst to give the cyclic alkylene carbonate which is in turn converted to the dialkyl carbonate. More particularly, the process utilizes the alkylene glycol obtained for the diphenyl carbonate preparation process (DPC process).

Abstract: The present invention relates to a method for automatically determining the relative solution viscosity and/or the melt volume flow rate of a polymer, during a phase of the process for producing the polymer, where the polymer is in a solution with 10 to 20% by weight of the polymer in an organic solvent. The method includes continuously removing a substream of the polymer solution from a component of the process for producing the polymer, wherein the polymer solution is essentially free from inorganic salts; removing a sample having a volume of from 1 to 10 ?l from the substream; introducing the sample into a gel permeation chromatography apparatus and determining the gel permeation chromatography data for the polymer; and automatically determining the relative solution viscosity and/or the melt volume flow rate of the polymer from the data obtained from the gel permeation chromatogram, on the basis of calibration relationships.

Abstract: Disclosed are random copoly(phosphonate carbonate)s with the high molecular weight and narrow molecular weight distribution exhibiting a superior combination of properties compared to prior art.

Abstract: A process is described for producing polycarbonate and utilizing at least some of the process waste water by concentrating the sodium chloride-containing waste water phases for the electrolysis using osmotic membrane distillation, if appropriate with simultaneous dilution of the sodium hydroxide solution obtained from the electrolysis for the polycarbonate production process.

Abstract: Processes comprising: reacting a dialkyl carbonate and an aromatic hydroxy compound in the presence of a transesterification catalyst in a first reaction column, the first reaction column comprising a top section, a bottom section, a rectifying section in an upper portion of the column and a reaction zone below the rectifying section; feeding a bottom product from the first reaction column to a further reaction column; the bottom product comprising a diaryl carbonate, an alkylaryl carbonate, or both, and residual unreacted dialkyl carbonate and aromatic hydroxy compound; the further reaction column comprising a top section, a rectifying section in an upper portion of the column and a reaction zone below the rectifying section; and reacting the residual unreacted dialkyl carbonate and aromatic hydroxy compound in the further reaction column; feeding a process stream to a distillation column, the process stream comprising a mixture of unreacted dialkyl carbonate and one or more reaction-product alcohols drawn f

Abstract: The invention relates to a process for extruding plastic compositions, in particular polymer melts and mixtures of polymer melts, above all thermoplastics and elastomers, particularly preferably polycarbonate and polycarbonate blends, also with the incorporation of other substances such as for example solids, liquids, gases or other polymers or other polymer blends with improved optical characteristics, with the assistance of a multi-screw extruder with specific screw geometries.

Abstract: Processes comprising: transesterifying a dialkyl carbonate and an aromatic hydroxyl compound in the presence of a transesterification catalyst to provide a diaryl carbonate product comprising the transesterification catalyst as an impurity; subjecting the diaryl carbonate product to distillation in a first distillation column having an upper part and a lower part, wherein the upper part comprises a rectifying section and the lower part comprises a stripping section; and withdrawing a first sidestream from the first distillation column, wherein the first sidestream comprises a purified diaryl carbonate.

Abstract: The invention provides a process for the preparation of diaryl carbonates and/or alkylaryl carbonates from dialkyl carbonates and aromatic hydroxy compounds using one or more intermediate condensers for improving heat integration.

Abstract: The invention provides a process for the preparation of diaryl carbonates and/or alkylaryl carbonates from dialkyl carbonates and aromatic hydroxy compounds using one or more intermediate condensers for improving heat integration.

Abstract: The invention relates to a process for the pretreatment of material surfaces in order to minimize the interaction between polycarbonate and metal and, in the processing and synthesis of polycarbonate, to obtain a high-quality polymer which in particular does not become discoloured and is free of insoluble constituents.

Abstract: The invention relates to a process for extruding plastic compositions, in particular polymer melts and mixtures of polymer melts, above all thermoplastics and elastomers, particularly preferably polycarbonate and polycarbonate blends, also with the incorporation of other substances such as for example solids, liquids, gases or other polymers or other polymer blends with improved optical characteristics, with the assistance of a multi-screw extruder with specific screw geometries.

Abstract: The invention relates to a process for extruding plastic compositions. The process in particular relates to the conveying, kneading and/or mixing of plastic compositions, in particular of polymer melts and mixtures of polymer melts, above all thermoplastics and elastomers, particularly preferably polycarbonate and polycarbonate blends, also with the incorporation of other substances such as for example solids, liquids, gases or other polymers or other polymer blends.

Abstract: 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.

Abstract: 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.

Abstract: The invention relates to a combined process for the preparation of polycarbonate by the phase boundary process and downstream electrolysis of sodium chloride-containing process wastewater.

Abstract: A process is described for producing polycarbonate and utilizing at least some of the process waste water by concentrating the sodium chloride-containing waste water phases for the electrolysis using osmotic membrane distillation, if appropriate with simultaneous dilution of the sodium hydroxide solution obtained from the electrolysis for the polycarbonate production process.

Abstract: 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.

Abstract: The invention relates to a process for preparing diaryl carbonates and/or alkyl aryl carbonates from dialkyl carbonates and aromatic hydroxy compounds using a reactive dividing wall column.