Production method of polyacetal resin composition

A method for producing a polyacetal resin composition, the polyacetal resin composition comprising at least:

• 100 parts by mass of a polyacetal polymer (A);
• 0.01 to 0.50 parts by mass of an aliphatic carboxylic acid hydrazide (B);
• 0.001 to 0.50 parts by mass of a hydantoin compound having two hydrazinocarbonylalkyl groups (C);
• and
• 0.001 to 0.30 parts by mass of an alkaline earth metal salt of aliphatic carboxylic acid (D),
• wherein
• a total amount of the components (B) and (C) with respect to 100 parts by mass of the polyacetal polymer (A) is 0.03 to 0.55 parts by mass, and
• wherein the polyacetal polymer (A) is a polyacetal copolymer obtained by copolymerizing trioxane as a principal monomer (a) with one or more types of compounds selected from a cyclic ether having at least one carbon-carbon bond and a cyclic formal having at least one carbon-carbon bond as a comonomer (b) using a heteropolyacid represented by general formula (1) as a polymerization catalyst (c) to obtain a reaction product, adding a carbonate, hydrogen carbonate, or carboxylate of an alkali metal element or an alkaline earth metal element, or a hydrate thereof, or a hydroxide of an alkali metal element or an alkaline earth metal element (d) to the reaction product to obtain a mixture, and subjecting the mixture to melt kneading treatment to deactivate the polymerization catalyst (c),
• Hm[M1x.M2yOz].nH2O (1)
• wherein in the formula (1), M1 represents a central element consisting of one type or two types of elements selected from P and Si;
• M2 represents at least one coordination element selected from W, Mo and V;
• x represents an integer of 1 or greater and 10 or less;
• y represents an integer of 6 or greater and 40 or less;
• z represents an integer of 10 or greater and 100 or less;
• m represents an integer of 1 or greater;
• and n represents an integer of 0 or greater and 50 or less.