β-二酮铝和β-二酮酯铝催化合成聚对苯二甲酸乙二醇酯

Catalytic synthesis of poly(ethylene terephthalate)in presence of aluminum β-diketones and aluminum β-ketoesters

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 aluminum β-diketones and aluminum β-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 aluminum β-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）.