PET生产中二甘醇含量的影响因素分析

Analysis on influential factors on diethylene glycol content during PET production

在300 t/d聚合装置上,采用德国吉玛公司五釜工艺流程直接酯化连续生产聚对苯二甲酸乙二醇酯(PET),探讨了PET生产过程中二甘醇(DEG)的生成及相关影响因素。结果表明:PET生产中DEG的生成主要发生在酯化Ⅰ阶段;原料质量及工艺条件是DEG含量的主要影响因素;生产中,控制精对苯二甲酸(PTA)粒径在165~195μm、酯化Ⅰ温度260~265℃、酯化Ⅱ温度265~270℃、乙二醇(EG)/PTA摩尔比1.58~1.65、酯化Ⅰ压力65~75 k Pa、生产负荷270~330 t/d,可稳定PET产品中DEG含量;相比锑系催化剂,使用钛系催化剂时,DEG生成量较少。

Polyethylene terephthalate（ PET） was prepared on a 300 t/d polymerization plant applying five-reactor continuous direct esterification technology of Zimmer Co.,Germany. The formation of diethylene glycol（ DEG） and the influential factors were discussed during the production process of PET. The result showed that the formation of DEG dominantly occurred at the esterification Ⅰ stage during the production of PET; the primary influential factors on DEG content were the feedstock quality and process conditions; the DEG content of PET could remain stable by controlling purified terephthalic acid（ PTA） particle size of165-195 μm,esterification Ⅰ temperature 260-265 ℃,esterification Ⅱ temperature 265-270 ℃,ethylene glycol（ EG）/PTA mole ratio 1. 58-1. 65,esterification Ⅰ pressure 65-75 k Pa,production load 270-330 t/d; and titanium catalyst provided lower DEG yield than antimony catalyst.