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采用熔融酯交换法,以碳酸二苯酯(DPC)和双酚A(BPA)为原料合成聚碳酸酯(PC).考察了乙酰丙酮(HACAC)类金属配合物催化剂的活性,以及催化剂活性与相应金属离子螯合配位作用的关系.以不同乙酰丙酮金属配合物为催化剂合成的PC的特性黏数([η])对相应金属离子二苯甲酰甲烷(DBM)配合物的稳定常数的对数值(lgβ1)作图,得到1个双火山型曲线,证明DPC与BPA的熔融酯交换缩聚反应是受乙酰丙酮阴离子的碱性作用和金属离子的螯合配位作用共同影响的.通过比较用各种催化剂合成的PC的性质,发现乙酰丙酮锂(LiACAC)是一种优良的催化剂,可以用来合成分子量超过40000([η]=0.710 dL.g-1)、低支化物(Fries产物)含量、低分散(PDI=2.12)的PC.以LiACAC为催化剂,考察了催化剂用量、反应物配比、酯交换阶段压力以及温度等条件对反应的影响.最佳反应条件为,LiACAC的用量为1.5×10-4mol/mol BPA、原料配比nDPC∶nBPA=1.08、酯交换阶段压力设在4000 Pa、缩聚反应阶段反应温度为260℃.
Polycarbonate (PC) was synthesized by melt transesterification method using diphenyl carbonate (DPC) and bisphenol A (BPA) as raw materials.The activity of the catalyst of metal acetylacetone (HACAC) The corresponding metal ion chelating coordination relationship between the different acetylacetone metal complex as a catalyst for the synthesis of PC intrinsic viscosity ([η]) of the corresponding metal ion dibenzoylmethane (DBM) complex stability constants The logarithm value (lgβ1) is plotted to get a double volcano curve, which proves that the melt transesterification polycondensation reaction between DPC and BPA is influenced by both the basic effect of acetylacetone anion and chelating coordination of metal ions. LiACAC, an excellent catalyst, was found to be useful as a catalyst for synthesizing PC with molecular weights of more than 40,000 ([η] = 0.710 dL.g-1), low branchers (Fries product ), Low dispersion (PDI = 2.12) of PC.The LiACAC catalyst was used to study the influence of the amount of catalyst, the ratio of reactants, the pressure of transesterification stage and the temperature on the reaction.The optimum reaction conditions were the amount of LiACAC 1.5 × 10-4mol / mol BPA, with raw materials nDPC:nBPA = 1.08, the transesterification stage pressure was set at 4000 Pa, the polycondensation reaction stage the reaction temperature was 260 ℃.