聚酯熔体可以用于制备聚酯切片和熔体直接纺丝
涤纶的生产过程包括聚酯熔体合成和熔体纺丝两部分。合成聚酯的原料为聚对苯二甲酸和乙二醇,主要从石油裂解获得,也可从煤和天然气取得。石油加热裂解得到甲苯、二甲苯和乙烯等,经化学加工后可得到对苯二甲酸或对苯二甲酸二甲酯及乙二醇。在早期涤纶生产中由于对苯二甲酸不易精制,曾用对苯二甲酸二甲酯和乙二醇为原料。
Polyester production process includes two parts: polyester melt synthesis and melt spinning. The raw materials for the synthesis of polyester are poly (terephthalic acid) and ethylene glycol, which are mainly obtained from petroleum cracking, and also from coal and natural gas. Toluene, xylene and ethylene can be obtained by pyrolysis of petroleum, and terephthalic acid, dimethyl terephthalate and glycol can be obtained by chemical processing. In the early production of polyester, dimethyl terephthalate and glycol were used as raw materials because terephthalic acid was not easy to refine.
1965年对苯二甲酸的精制获得成功,使涤纶生产工序减少,成本降低。用对苯二甲酸和乙二醇为原料生产的涤纶逐年都有增加。缩聚:将对苯二甲酸二甲酯和乙二醇进行酯交换,生成的对苯二甲酸二乙二醇酯低聚物,在280~290℃和真空条件下缩聚而得聚对苯二甲酸乙二醇酯;或将对苯二甲酸与乙二醇直接酯化,然后对苯二甲酸乙二酯进行缩聚获得聚酯熔体。聚酯熔体可以用于制备聚酯切片和熔体直接纺丝。聚酯切片是将聚酯熔体经铸带、切粒而得到切片 。
In 1965, terephthalic acid was refined successfully, which reduced polyester production process and cost. Polyester produced with terephthalic acid and glycol as raw materials has increased year by year. Polycondensation: poly (ethylene terephthalate) is produced by transesterification of dimethyl terephthalate and ethylene glycol, polycondensation at 280-290 ℃ and vacuum; or directly esterification of terephthalic acid and ethylene glycol, and polycondensation of ethylene terephthalate to obtain polyester melt. Polyester melt can be used to prepare PET chips and melt direct spinning. Polyester chips are made by casting polyester melt into strips and cutting chips.