Patent ID: 7217783

Claim:
A method for purifying an oxytertamethylene glycol copolymer, obtained by copolymerizing tetrahydrofuran and a diol represented by the following formula (1): wherein each of R1 and R2 independently represents a hydrogen atom or a hydrocarbon group having from 1 to 5 carbon atoms; and each of p, q and r independently represents an integer of from 0 to 6, with the proviso that the sum of p, q, and r is not less than 2, from a copolymerization mixture comprising an oxytertamethylene glycol copolymer and the unreacted diol, which comprises subjecting said reaction mixture to continuous distillation in the presence of fresh tetrahydrofuran at a temperature of from 80 to 160° under a pressure of from 5 to 760 Torr, said fresh tetrahydrofuran being added in an amount which is not less than the weight of said unreacted diol contained in the reaction mixture, to thereby distill off said unreacted diol from said reaction mixture together with said fresh tetrahydrofuran.