| abstract |
To prepare a thermally very stable polyacetal copolymer containing a very small amount of unstable parts in a high yield according to a simple process wherein an isopolyacid or an acid salt thereof is used as the polymerization catalyst in the copolymerization of trioxane as the principal monomer with a comonomer copolymerizable therewith, and wherein deactivation of the catalyst can be effected simply without fail through contact with a basic gas after polymerization without the necessity for any washing step. In the preparation of a polyacetal copolymer by the copolymerization of trioxane as the principal monomer with a cyclic ether or cyclic formal having at least one carbon-carbon bond as a comonomer, the copolymerization is effected using an isopolyacid or an acid salt thereof as the polymerization catalyst, followed by contact with a basic gas as a deactivator to deactivate the catalyst, and subsequent heat-melting treatment of the resulting crude polymer intact without washing thereof. |