Abstract: The present invention relates to a distillation process for the purification of carbonic acid diaryl esters.

Abstract: The present invention relates to a process for the continuous production of diaryl carbonates by reaction of aromatic hydroxy compounds with phosgene in the presence of heterogeneous catalysts.

Abstract: The invention relates to a transesterification process for the production of thermoplastic, solventless oligo-/polycarbonates in which aromatic diphenols and carbonic acid diaryl esters are combined and reacted in gaseous form.

Abstract: The present invention provides a two-stage melt process for the manufacture of thermoplastic, solvent-free, low-branched polycarbonates with low OH end-group contents with the use of ammonium or phophonium catalysts in the first stage and alkali and alkaline earth catalysts in the second stage.

Abstract: The invention relates to a process for the chemical recycling of polycarbonates by catalyzed reaction with diaryl carbonates to oligocarbonates which are crystallized, purified and then polycondensed back to polycarbonates, insoluble constituents optionally being removed before the crystallization step.

Abstract: The present invention provides a melt process for the manufacture of thermoplastic solvent-free polycarbonates with the use of a continuously operated tubular reactor for monophenol vaporization.

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: A continuous process for splitting an aromatic polycarbonate resin is disclosed. Accordingly there are reacted in a distillation column and in the presence of a catalyst(i) a polycarbonate resin in solution with(ii) methanolto produce a dihydroxy compound and dimethyl carbonate. The solution which contains polycarbonate and monohydroxy compound solvent exclusive of methanol is fed into the upper section of said column and the methanol is fed into the lower section of the column. The methanol is fed in the form of a mixture containing methanol and about 1-50 weight percent of dimethyl carbonate. The dimethyl carbonate thus produced is removed from an upper section of the column and the dihydroxy compound is removed from a lower section of the column.

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 is disclosed for cleaving polycarbonates into bisphenols and diaryl carbonates by transesterifying with phenols in the presence of catalysts. The process entails isolating bisphenols from the product of the transesterification, and subjecting the remaining mixture which contains phenols and diaryl carbonates to flash distillation. The phenols and diaryl carbonates are distilled off and separated, and the diaryl carbonates are recovered.

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

Abstract: A process for the continuous splitting of polycarbonates into dihydroxy compounds and carbonic acid esters is disclosed. Accordingly there are reacted in a distillation column a polycarbonate resin and a monohydroxy compound in the presence of a transesterification catalyst. The polycarbonate, in molten form or as a solute, is continuously fed into the upper part of the column and the monohydroxy compound in vapor phase is continuously fed into the lower part of the column. The resulting carbonic acid ester and dihydroxy compounds are continuously being removed from the column. The process is eminently suitable for the recycling of polycarbonate waste.

Abstract: Crosslinked copolymers ofA) cyclic aliphatic esters andB) cyclic aliphatic carbonatesin which part of B contains crosslinking-active side groups,their production and their use for the production of films.