Abstract: A process for the isolation of polycarbonate produced by the interfacial polymerization process is disclosed. Accordingly, the process entails (a) evaporating the organic solvent from the solution that contains solvent and polycarbonate to obtain a material system that contains 90 to 99.95% polycarbonate, the percent being relative to the weight of the system, and (b) passing the material system through inlet openings of a separating vessel to obtain a plurality of streams of polycarbonate, on entry into the inlet openings said material system being supersaturated with volatile constituents to an extent of at least 1 bar and having a temperature of 250° to 340° C. and a flow rate of 0.1 to 20 kg/hour, and (c) degassing the streams in the separating vessel wherein the pressure is 0.1 to 20 mbar to effect degassing of the polycarbonate.

Abstract: The invention describes a process for the preparation of polycarbonate. The process includes (a) transesterifying at least one aromatic dihydroxyaryl compound and a diaryl carbonate in the melt in the presence of a catalyst, (b) mixing the melt obtained in step (a) with a foaming agent (c) passing the mixture at 250 to 340° C. through inlet openings of a separating vessel at a rate of 0.1 to 20 kg/hour, to obtain a plurality of streams of foamed polycarbonate and degassing the streams of foamed polycarbonate in the separating vessel wherein the pressure is 0.1 to 20 mbar.

Abstract: Polycarbonate substrates, the preparation of which is based on 1,1-bis-(4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, and their use for producing shaped articles with particularly high purity and extremely high surface brilliance and also the shaped articles which can be produced from the polycarbonate substrate are described.

Abstract: A process for the preparation of optical data carriers made of a particualr polycarbonate is disclosed. The polycarbonate is prepared by the phase boundary process that entails reacting at least one dihydroxydiarylalkane in the form of its alkali metal salts with phosgene in the heterogeneous phase in the presence of sodium hydroxide solution and an organic solvent. The process is characterized in that the feedstock have but low content of Fe, Cr, Ni, Zn, Ca, Mg, Al metals or homologues thereof, and in that the organic solvent is separated off, and in that the polycarbonate which is obtained is worked up. The resulting polycarbonate is particularly useful in producing optical data carriers.

Abstract: A process for the preparation of polycarbonate by the phase boundary process is disclosed. The process entails reacting at least one dihydroxydiarylalkane in the form of its alkali metal salts with phosgene in the heterogeneous phase in the presence of sodium hydroxide solution and an organic solvent. The process is characterized in that the feedstock have but low content of Fe, Cr, Ni, Zn, Ca, Mg, Al metals or homologues thereof, and in that the organic solvent is separated off, and in that the polycarbonate which is obtained is worked up. The resulting polycarbonate is particularly useful in producing transparent shaped articles.

Abstract: Polycarbonate substrates having low concentration of defects are disclosed. The substrates are suitable for producing molded articles characterized by low cloudiness.

Abstract: A process for producing polymer pellets is disclosed. The process that is particular suitable for making polycarbonate pellets entails extruding a polymer melt, cooling the extrudate by contacting it with a cooling fluid and pelletizing the solidified polymer. The process is characterized in that the cooling fluid has a solids particle content of at most 10 ppm.

Abstract: A method for producing polycarbonate based on 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexanone and 4,4-(metaphenylene diisopropyl) diphenol is disclosed. The method is characterized in that the recovery and/or further processing of the polycarbonate is performed at temperatures below 290° C. The polycarbonate thus produced has high purity and high transmission and is suitable for the manufacture of optical data stores.

Abstract: An improvement to the melt transesterification reaction of diaryl carbonate with dihydroxy aryl compound is disclosed.

Abstract: Polycarbonate substrates, the preparation of which is based on 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexanone, and their use for producing shaped articles with particularly high purity and extremely high surface brilliance and also the shaped articles which can be produced from the polycarbonate substrate are described.

Abstract: A method for producing bisphenol A in prill form is disclosed. Molten bisphenol is top-fed into a prilling tower via a plate containing a plurality of nozzles. A gas coolant guided through a circuit is led into said tower in a counter flow direction. The prills are cooled to about room temperature, collected at the bottom of the tower and removed. Also disclosed is the device for carrying out the inventive method and the prills thus produced.

Abstract: A container made of polycarbonate resin is disclosed. The container is characterized in that the polycarbonate is prepared by the phase interface process that is characterized in that the aqueous solution of an alkali salt of a bisphenol used, contains dissolved oxygen in an amount less than 150 ppb. The process for making the container is also disclosed.

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: The present invention provides the use of impact resistant, stress cracking resistant copolycarbonates with particularly good low temperature properties for applications in which particularly good low temperature properties are required, e.g., for automobile construction or external applications, and new copolycarbonates themselves.

Abstract: The present invention provides the use of impact resistant, stress cracking resistant copolycarbonates with particularly good low temperature properties for applications in which particularly good low temperature properties are required, e.g., for automobile construction or external applications, and new copolycarbonates themselves.

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: A two stage interfacial polycondensation process for the production of carbonic acid diaryl ester is disclosed. The invention concerns an improvement to the process that entails forming in a first stage a reaction mixture that contains an inert solvent, at least one monophenol, phosgene, and aqueous alkali hydroxide solution, passing said reaction mixture to a second stage through at least one constriction at a velocity of 3 to 15 m/s under conditions designed to expose the mixture to a pressure drop of 0.1 to 2.5 bar, and in said second stage passing said mixture through at least one dispersing element at a velocity of 2 to 10 m/s under conditions designed to expose the mixture to a pressure drop of 0.1 to 0.5 bar. The resulting product is characterized by its purity and suitability for the manufacture of polycarbonates in the melt transesterification process.

Abstract: A process of preparing bisphenol A having low residual contents of oxygen and phenol is described. The process involves: (a) melting mixed crystals of bisphenol A and phenol under a nitrogen atmosphere at a temperature of 100° C. to 120° C.; (b) feeding continuously the melt formed in step (a) into the top of a distillation unit under conditions of 120° C. to <160° C. and a pressure of >80 mbar to 200 mbar; (c) feeding contemporaneously with step (b) nitrogen into the bottom of the distillation unit; (d) allowing the melted feed material and the nitrogen feed to contact each other within the distillation unit, thereby forming a concentrated melt material having (i) a phenol content reduced to 10 to 25 wt. %, and (ii) a reduced oxygen content (e.g., an oxygen content of <1 ppm); and (e) optionally passing a stream of nitrogen through the concentrated melt material under conditions of at least atmospheric pressure, 180° C. to 220° C. and a nitrogen partial pressure of 1 to 1.

Abstract: A process for the preparation of polycarbonate resins having a low yellowness index is described. The process involves converting phosgene with a sodium bisphenolate solution by means of a phase interface process performed with the exclusion of oxygen. The sodium bisphenolate solution used in the process has a dissolved oxygen content of <150 ppb. Also described are optical data storage media prepared from the polycarbonate of the present invention.

Abstract: A process for producing bis(4-hydroxyaryl)alkane is disclosed. The process comprise in sequence the steps of (a) passing inert gas through a melt at 150 to 230° C. that contains bis(4-hydroxyaryl)alkane and other aromatic hydroxy compounds, under conditions designed to remove said other aromatic hydroxy compounds from said melt and to obtain a stream of inert gas that contains said other aromatic hydroxy compounds (b) condensing the stream obtained in (a) to remove said other aromatic hydroxy compound, and to obtain a stream of inert gas, and (c) purifying and compressing the stream of inert gas obtained in (b), and recycling to step (a).