A polyoxymethylene multi-copolymer obtainable by copolymerizing (a) trioxane, (b) at least one cyclic ether or formal compound chosen from the group of ethylene oxide, 1,3-dioxolane, 1,3-dioxepane, 1,3,5-trioxepane and 1,3,6-trioxocane, and (c) at least one compound chosen from the group of glycidyl phenyl ether, styrene oxide and glycidyl naphthyl ether, and characterized in that the number average molecular weight of said polyoxymethylene multi-copolymer is from 10,000 to 100,000, that the melting point (Tm) and crystallization temperature (Tc) there of are in a relationship of Tm - Tc