PURPOSE: To enhance oxygen barrier properties by reacting diglycidyl ether of a divalent aromatic compd. and other dihydric phenol.

CONSTITUTION: Solid thermoplastic polyether having a repeating unit represented by formula I (wherein A is carbonylphenylene, m-phenylene, sufonyldiphenylene, p-phenylene or a divalent aromatic part selected from combinations of them; B is divalent aromatic parts other than A or a combination thereof; R is H or monovalent hydrocarbon, x is a number sufficient to reduce oxygen permeability of copolyether to a value lower to a degree possible to measure than the value of polyether of the repeating unit represented by a formula II but 0.85 or less when A is carbonyldiphenylene, sulfonyldiphenylene or p-phenylene) is obtained by reacting diglicydil ether of a divalent aromatic compd. with other dihydric phenol.