To obtain a colorless polyester which has a low crystallization rate and an be spun at a high speed into fibers by subjecting a monomer formed by the esterification of a dicarboxylic acid or by the alcoholysis of an alkyl ester of a dicarboxylic acid to polycondensation.
A monomer (e.g. ethylene terephthalate) is produced by the esterification of a dicarboxylic acid (e.g. terephthalic acid) or by the alcoholysis of an alkyl ester of a dicarboxylic acid. The monomer is subjected to polycondensation in the presence of a catalyst system to give a colorless polyester having a low crystallization rate. A suitable catalyst system contains an antimony or germanium compd. (e.g. antimony acetate) in such an amt. that the finally resulting polymer contains 5-149.9ppm antimony or germanium and a compd. of a metal selected from among metals of the groups I-IVa, I-VIIb, VIII, and lanthanoids (e.g. cobalt acetate) in such an amt. that the finally resulting polymer contains 0.1-90ppm above-selected metal, subject to the condition that the total amt. of metals contained in the finally resulting polymer is lower than 150ppm.
RUIJI PEROSHIINI
ERUNESUTO OTSUKIERURO
UUGO ROMAANO
