β-二酮铝和β-二酮酯铝催化合成聚对苯二甲酸乙二醇酯

摘要

采用对苯二甲酸(TPA)和乙二醇(EG)为原料,以自制的β-二酮铝和β-二酮酯铝为催化剂经酯化、缩聚,制得聚对苯二甲酸乙二醇酯(PET).探讨了反应条件对合成反应的影响.结果表明:β-二酮酯铝和乙酰丙酮铝优于其他β-二酮铝.EG与TPA的摩尔比为1.2∶1、催化剂的用量为0.5%(与TPA的摩尔比),酯化反应温度为260 ℃,缩聚反应温度为280℃,可制得PET,其特性黏度为0.82 dL/g,二甘醇为8.5 mol/t和端羧基值为66.36μmol/g.对β-二酮铝和β-二酮酯铝的催化机理也做了初步探讨,红外(IR)和核磁(NMR)表征了催化剂及产品PET的结构.%Poly ( ethylene terephthalate) (PET) was prepared from purified terephthalic acid (TPA) and ethylene glycol (EG) with self-made aluminumβ-diketones and aluminumβ-ketoesters as catalyst via esterification and polycondensation. The effects of reaction conditions on the synthesis were discussed. The results show that aluminum acetylacetonate and aluminum β-ketoesters have higher catalytic activity than other aluminum β-diketones. The PET with intrinsic viscosity of 0.82 dL/g, diethylene glycol (DEG) of 8.5 mol/t and carboxyl terminal group value of 66.36 μmol/g can be produced under the conditions as follows: molar ratio 1.2∶ 1 of EG to TPA, catalyst content of 0. 5％ based on 1 mol TPA, esterification temperature 260 ℃, polycondensation temperature 280 ℃. The catalytic mechanism of aluminumβ-diketones and β-ketoesters was proposed to explain these observations. PET sample and catalyst were characterized by infrared spectrophotometer (FTIR) and nuclear magnetic resonance (NMR).