Abstract: A method for the manufacture of a polycarbonate which comprises reacting a carbonate precursor with a dihydroxy compound in the presence of an aqueous base in an inert organic solvent optionally containing a molecular weight regulator to form an oligomeric polycarbonate, wherein the reaction between the dihydroxy compound and the carbonate precursor is about 80 to about 99% completed; removing the inert organic solvent and the aqueous base to isolate the oligomeric polycarbonate; and transesterifying the isolated oligomeric polycarbonate to form a polymeric polycarbonate at a temperature and pressure effective to remove trace amounts of residual solvent. This method eliminates some of the problems of the prior art such as the removal of solvent from high molecular weight polycarbonate, which is both cumbersome, energy intensive and expensive.

Abstract: A method for producing a thermoplastic sheet includes extruding a composition including a melt polycarbonate resin having a Fries content of about 10 ppm to about 2000 ppm. The composition enables the sheet to be extruded with excellent uniformity.

Abstract: A method for producing a thermoplastic sheet includes extruding a composition including a melt polycarbonate resin having a Fries content of about 10 ppm to about 2000 ppm. The composition enables the sheet to be extruded with excellent uniformity.

Abstract: A process for preparing an end-capped polycarbonate comprises melt reacting an aromatic dihydroxy compound, a carbonic acid diester, and optionally a catalyst in a prepolymerization vessel to form a polycarbonate product; transferring the polycarbonate product from the prepolymerization vessel; mixing the polycarbonate product with an end-capping agent under hermetic seal at a pressure of at least about 760 mm Hg; and transferring the polycarbonate product and end-capping agent mixture to a postpolymerization vessel to endcap the polycarbonate product.

Abstract: A process for preparing an end-capped polycarbonate comprises melt reacting an aromatic dihydroxy compound, a carbonic acid diester, and optionally a catalyst in a prepolymerization vessel to form a polycarbonate product; transferring the polycarbonate product from the prepolymerization vessel; mixing the polycarbonate product with an end-capping agent under hermetic seal at a pressure of at least about 760 mm Hg; and transferring the polycarbonate product and end-capping agent mixture to a postpolymerization vessel to endcap the polycarbonate product.

Abstract: Brine produced in an interfacial polycarbonate plant can be treated to render it useful for recycle to the electrolytic cell, which is used in the production of chlorine. The waste brine stream is combined with ozone to produce an ozonated brine in which the amounts of organic contaminants such as phenol, bisphenol A and chloromethyltrimetlhyl ammonium chloride is reduced. The ozonated brine is then acidified to remove carbonates and produce a decarbonated brine which is then concentrated to produce a treated brine in which the concentration of NaCl is at least 10 wt % NaCl. A filtration step may be included prior to the ozonation to remove particulate impurities. When used in an interfacial polycarbonate plant in combination with chlorine, phosgene and polycarbonate producing facilities, this allows recycling of the brine waste stream and this provides an environmentally superior and highly cost effective method for the producing polycarbonate.

Abstract: A method of preparing polycarbonate by the melt process comprising the steps of: a) melting a dihydric phenol and a diester of carbonic acid for a time and at a temperature sufficient to form a melt; and thereafter introducing a catalyst composition comprising a tetraorganophosphonium salt or a derivative thereof and 1) an alkali and/or alkali earth metal compound or derivative thereof or 2) a less active alkali and/or alkali earth metal derivative thereof into the melt; and b) oligomerizing the product from step a) to a number average molecular weight of from about 3000 to about 7500; and c) polymerizing the product from step b) to a number average molecular weight of from about 16,000 to about 35,000.