Improved process for preparing poly(ethylene terephthalate)

Abstract From the Canadian patent

A continuous process is disclosed for direct esterfication of terephthalic acid with ethylene glycol followed, by low-pressure polymerization in a continuous polymerizer and in a finisher polymerizer to produce polyester suitable for melt-spinning into yarn for textile uses. Vapors from the polymerizers are condensed in spray condensers to recover glycol liquid, which is recycled to the direct esterification reaction. Efficient operation of the spray condensers at absolute pressures of less than 60 millimeters of mercury is achieved by addition of substantially dry ethylene glycol to lower the water content of condensate used in the sprays.