Poly-acetal copolymers prodn.

摘要

Process for prodn. of polyacetal copolymers comprises (a) copolymerising trioxan as principal monomer with a comonomer comprising a cyclic ether or cyclic formal which contains at least one carbon-carbon bond, in the presence of a polymerisation catalyst comprising a heteropolyacid of formula HxMm.M'nOl.yH2O (I) in which M = at least one central element chosen from P and Si, M' = at least one coordinated element chosen from W, Mo and V, l = 10-100, m = 1-10, n = 6-40, x = a whole number /-1 and y = 0-50, or an acid salt of this; (b) deactivating the catalyst by adding 0.01-10 wt. % w.r.t. the resulting crude polymer of a soln. contg. a deactivating agent for the catalyst; (c) reducing the amt. of residual monomers to 10 wt. % or less w.r.t. the total amt. of polymers used originally and (d) subjecting the unwashed crude polymer to a hot melt treatment. Also claimed is a similar process for prodn. of polyacetal copolymers in which the catalyst deactivation in stage (b) i s accomplished by contact with a basic gas.