Producing a polyethylene terephthalate based polymer from a lower dialkyl ester of a dicarboxylic acid and a glycol

摘要

A process for producing PET based polyester polymers from a lower dialkyl ester of a dicarboxylic acid and a glycol selected from the class of ethylene glycol, diethylene glycol, polyethylene glycol, blends of ethylene glycol and propane and/or butane diol, or mixtures of two or more of these, using the novel catalyst system and a small amount of dicarboxylic acid is described. The novel catalyst composition includes from about 10 ppm to about 150 ppm manganese; from about 50 ppm to about 250 ppm lithium; preferably from about 10 ppm to about 40 ppm cobalt; and from about 200 ppm to about 400 ppm antimony, all amounts being based upon the expected yield of the polyester based polymer. The process for using the novel catalyst composition to make polyester includes the step of employing an effective catalytic amount of manganese and lithium in an ester interchange reaction where the lower dialkyl ester and glycol produce monomer; and using an effective catalytic amount of cobalt and antimony in the polycondensation reaction and a small effective amount of dicarboxylic acid to convert the monomer to polyester. Using the novel catalyst composition and effective amount of dicarboxylic acid to produce a polyester based polymer drastically increases both the ester interchange rate and the polymerization rate, such that the ester interchange time and the polycondensation time are drastically reduced as compared to more conventional systems for producing polyester.