CONTINUOUS PROCESS FOR PRODUCING BIS(3-HYDROXYPROPYL) TEREPHTHALATE

摘要

A process for the continuous production of at least one of bis(3-hydroxypropyl) terephthalate and low molecular weight oligomers of 1,3-propanediol and terephthalic acid is disclosed. According to the process, preheated 1,3-propanediol (about 150 ~C to about 200 ~C) and preheated lower dialkyl esters of terephtalic acid (about 150 ~C to about 220 ~C) are combined in a mole ratio of about 1.2:1 to about 2.3:1 and fed to an ester exchange vessel where the mixture undergoes a continuous transesterification reaction. The liquid reaction mixture is continuously heated and mixed, at a temperature of about 215 ~C to about 250 ~C, and a pressure of about 800 mm Hg to about 1,000 mm Hg. Gaseous reaction products are continuously separated from the liquid reaction mixture, and a stream of liquid reaction products containing bis(3-hydroxypropyl) terephthalate and low molecular weight oligomers of 1,3-propanediol and terephthalic acid is continuously removed from a base portion of the ester exchange vessel.