An improved interfacial polycondensation polycarbonate process, the improvement comprising an initial equilibrated pH range of 11 to 13, a temperature range of 15.degree. to 40.degree. C., a carbonyl halide rate of addition of 0.03 to 0.3 moles per minute per mole of aromatic dihydroxy compound, and a chain stopper content of 0.02 to 0.05 moles per mole of aromatic dihydroxy compound. The resulting aromatic polycarbonate exhibits improved chemical and physical properties having a weight average molecular weight within a range of from about 25,000 to 65,000, and a monocarbonate content of less than about 400 parts per million.
METHOD FOR REDUCING METAL ION CONCENTRATION IN BRINE SOLUTION
申请人:——
公开号:US20010011645A1
公开(公告)日:2001-08-09
This invention relates to a method for removing impurities from a brine solution, the brine solution comprising a water soluble chelating agent, the method comprising the steps of:
a) adjusting the pH of the brine solution to a pH of from about 2 to about 4;
b) passing the brine solution through a first functionalized resin; the first functionalized resin having functional groups capable of removing multivalent metal cations from the brine solution;
c) adjusting the pH of the brine solution to a pH of from about 9 to about 11.5; and
d) passing the brine solution through a second functionalized resin; the second functionalized resin having functional groups capable of removing alkaline earth metal cations from the brine solution.
Aromatic polycarbonate chain terminated with a cyclic ester.
带有环酯结尾的芳香族聚碳酸酯链。
Aromatic polycarbonate end capped with branched chain alkyl acyl halide
申请人:General Electric Company
公开号:US04431793A1
公开(公告)日:1984-02-14
Aromatic polycarbonates end-capped with branched alkyl acyl halides and/or acids from four to seven carbon atoms, inclusive, provide higher heat resistance and better impact resistance after aging at elevated temperature compared with normal alkyl acyl agents. The resins of the invention are injection molded.
This invention relates to an extrusion method preparing polycarbonates from a solution of an oligomeric polycarbonate. A mixture of bis(methyl salicyl) carbonate (BMSC), BPA and a transesterification catalyst are first equilibrated at moderate temperatures to provide a solution of polycarbonate oligomer in methyl salicylate. The solution is then fed to a devolatilizing extruder, where the polymerization reaction is completed and the methyl salicylate solvent is removed. The solution comprising the oligomeric polycarbonate can also be pre-heated under pressure to a temperature above the boiling point of methyl salicylate and subsequently fed to a devolatilizing extruder equipped for rapid flashing off the solvent. The method provides polycarbonate with greater efficiency than the corresponding process in which unreacted monomers are fed to the extruder. Additionally, the method of the invention does not require the isolation of a precursor polycarbonate comprising ester-substituted phenoxy terminal groups.