Patent ID: 7928184

Claim:
A method of manufacturing a stabilized polyacetal resin, comprising the steps of: providing a polyacetal resin having an unstable terminal group, the polyacetal resin being the copolymerization reaction product of trioxane as a main monomer with cyclic ether and/or cyclic formal as a comonomer in the presence of a cationic polymerization catalyst, and applying a heat treatment to the polyacetal resin in the presence of an unstable terminal group decomposer selected from the following Group I, Group II, and Group III, thereby decreasing the unstable terminal group: unstable terminal group decomposer of Group I: (I) a quaternary ammonium salt of an acidic cyclic amide compound; unstable terminal decomposer of group II: (II) a quaternary ammonium salt of a polycarboxylic acid intramolecularly having four or more carboxyl groups and/or a quaternary ammonium salt of an aminocarboxylic acid intramolecularly having one or more carboxyl groups; unstable terminal group decomposer of Group III: (III) a quaternary ammonium salt, wherein a compound providing a counter-anion of a quaternary ammonium salt is at least one selected from the group consisting of the following (i) and (ii): (i) an acidic enol-based compound; and (ii) an acidic azole based compound.