More rapid mixed acid polyesters prodn. - by reacting aromatic acid with only a portion of the polyol in a first stage, then adding remainder and aliphatic acid

摘要

A 2-stage process for making polyesters (I) comprises reacting in a first stage isophthalic or terephthalic acid with sufficient of the polyol (II) to form an agitatable mixt but slightly less than the theoretical amt. needed to react with aromatic acid and the (subsequently added) (un)satd. aliphatic polycarboxylic acid (III). The mixt. is heated at >=190-230 degrees C, than the rest of (II) is added such that the temp. does not fall below 190 degrees C to give a Y2-ester mixt. This mixt. is than reacted in a second stage with (III) to produce (I). Processing time in the first stage, and thus in the overall process, is reduced, e.g. from 11 1/4 to 7 1/2 in the examples.