Disclosed is a method for producing polyesters by polymerizing terephthalic acid and/or its ester-forming derivative, and a glycol and/or its ester-forming derivative in a plant comprising an esterification device and a polycondensation device in series, while partly or wholly recycling the distillate from the esterification device and/or the polycondensation device that consists essentially of a glycol and/or its ester-forming derivative. The method comprises a step of continuously or intermittently measuring the content of at least one of water, the glycol and its ester-forming derivative in the distillate to be recycled, determining the amounts of the raw materials to be fed to the intended reaction device, on the basis of the data thus measured, and feeding the thus-determined amounts of the raw materials to the reaction device; or comprises a step of storing the distillate, prior to being recycled for the starting material, in a storing tank that has a capacity corresponding to the amount of the glycol and/or its ester-forming derivative to be fed to the esterification device for a period of 10 hours or more.
本发明公开了一种通过聚合
对苯二甲酸和/或其
酯类衍
生物以及
乙二醇和/或其
酯类衍
生物来生产聚酯的方法,聚合装置包括一个串联的酯化装置和一个缩聚装置,同时部分或全部回收来自酯化装置和/或缩聚装置的主要由
乙二醇和/或其
酯类衍
生物组成的馏分。该方法包括以下步骤:连续或间歇地测量待回收馏分中
水、
乙二醇及其酯形成衍
生物中至少一种物质的含量,根据所测量的数据确定送入预定反应装置的原料量,并将由此确定的原料量送入反应装置;或包括一个步骤,即在回收馏出物作为起始原料之前,将其储存在一个储存罐中,该储存罐的容量与将送入酯化装置的
乙二醇和/或其酯化衍
生物的量相当,储存时间为 10 小时或更长时间。