摘要:
Solid state polymerization of partially crystalline polycarbonate oligomers bearing ester-substituted terminal groups occurs at useful reaction rates despite their high level of endcapping. Partially crystalline polycarbonate oligomers having ester substituted terminal groups may be obtained in a single step by reaction of an ester substituted diaryl carbonate such as bis-methyl salicyl carbonate with a dihydroxy aromatic compound such as bisphenol A in the presence of a transesterification catalyst such as sodium hydroxide. Alternatively, amorphous oligomeric polycarbonates incorporating ester substituted endgroups may be obtained through careful control of the melt reaction conditions. The amorphous oligomeric polycarbonates are crystallized upon exposure to solvent vapor and subsequently undergo solid state polymerization at synthetically useful reaction rates.
摘要:
This invention relates to mixed dialkali metal salts of sulfuric acid containing at least one cesium equivalent useful in catalyst systems in melt polymerizations. The catalysts provide product with low branching side reaction products and good properties.
摘要:
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.
摘要:
High yields of ester-substituted diary carbonates such as bis-methyl salicyl carbonate were obtained by the condensation of ester-substituted phenols with phosgene in the presence of a phase transfer catalyst (PTC) and optionally a tertiary amine catalyst in a solvent free reaction system comprising an aqueous phase held at a pH of 8.3 or higher. The optimized conditions of the present invention use an excess of ester-substituted phenol relative to phosgene and high conversion of phosgene to ester-substituted diaryl carbonate is observed. The product ester-substituted diaryl carbonate may be conveniently isolated as a solid by filtration or as a liquid in which the excess ester-substituted phenols serves as solvent. The method represents an attractive route for the manufacture of bis methyl salicyl carbonate and ester-substituted diaryl carbonates generally. The ester-substituted diaryl carbonates are useful for the preparation and modification of polycarbonates.
摘要:
High yields of ester-substituted diary carbonates such as bis-methyl salicyl carbonate were obtained by the condensation of ester-substituted phenols with phosgene in the presence of a phase transfer catalyst (PTC) and optionally a tertiary amine catalyst in a solvent free reaction system comprising an aqueous phase held at a pH of 8.3 or higher. The optimized conditions of the present invention use an excess of ester-substituted phenol relative to phosgene and high conversion of phosgene to ester-substituted diaryl carbonate is observed. The product ester-substituted diaryl carbonate may be conveniently isolated as a solid by filtration or as a liquid in which the excess ester-substituted phenols serves as solvent. The method represents an attractive route for the manufacture of bis methyl salicyl carbonate and ester-substituted diaryl carbonates generally.
摘要:
A method of preparing block copolymers by solid state polymerization is described. A mixture of a partially crystalline polycarbonate having activated terminal aryloxy groups, for example terminal methyl salicyl groups, when heated together with an oligomeric polyester having reactive terminal hydroxy groups under solid state polymerization conditions affords block copolymers. The activated terminal aryloxy groups play a key role in preserving the block lengths of the starting materials. A control sample in which the partially crystalline polycarbonate lacks activated terminal aryloxy groups, for example polycarbonates substituted by phenol, affords a much lower molecular weight, more highly randomized copolymer product. The product block copolymers are useful as “weatherable” plastic materials.
摘要:
In an embodiment, the present invention is directed a method and an apparatus comprising irradiating a polymer sample with at least one wavelength of substantially monochromatic light and monitoring radiation emitted by the polymer sample which is correlated to sample hydrolysis and a change in polymer molecular weight.
摘要:
A method for preparing a molded article includes the steps of (a) obtaining a polycarbonate resin and (b) molding the polycarbonate resin. The polycarbonate resin is made by a transesterification reaction using an activated diaryl carbonate such that the polycarbonate is susceptible to the formation of internal ester linkages (IEL). The method occurs with the proviso that the polycarbonate resin, the molding conditions or both are selected to control the amount of IEL formed during the molding process to a level of less than 0.4 mol %.
摘要:
Polycarbonates incorporating terminal carbonate groups derived from ester-substituted activated carbonates in a transesterification process have unfavorable properties with respect to color, hydrolytic stability and thermal stability, particularly when the polycarbonate containing such end groups is molded. The number of activated carbonate end groups formed during the melt transesterification formation of polycarbonate can be reduced by reacting a dihydroxy compound with an activated diaryl carbonate in the presence of an esterification catalyst to produce a polycarbonate, in the presence of a monohydroxy chainstopper such as para-cumyl phenol in an amount that results in 35 to 65 mol % of the end groups being derived from the monohydroxy chainstopper. Suitably, the reactants are provided such that the molar ratio of activated diaryl carbonate to the total of dihydroxy compound plus ½ the chainstopping reagent that is less than 1.
摘要:
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.