Abstract: Provided is a method using a molded article in direct contact with a liquid containing an acidic component which includes (i) producing a resin composition comprising (A) 100 parts by weight of a polyacetal resin, (B) 0.01 to 5 parts by weight of an antioxidant, (C) 0.01 to 10 parts by weight of a calcium or zinc metal salt of a C10 to C34 long chain fatty acid, and (D) 0.001 to 5 parts by weight of a nitrogen-containing compound which is selected from the group consisting of melamine or its derivatives, guanamine or its derivatives, melamine formaldehyde resins, hydrazide compounds, polyamides and polyacrylamides; (ii) producing a molded article comprising the composition; and (iii) bringing a liquid containing an acidic component into direct contact with the molded article.

Abstract: Provided is a polyacetal resin molded article having an excellent acid resistance, used for parts contacting with a liquid containing an acidic substance. Specifically, a molded article having excellent durability under direct contact with a liquid containing an acidic component is obtained by molding the composition of (A) 100 parts by weight of a polyacetal resin, (B) 0.01 to 5 parts by weight of an antioxidant, and (C) 0.01 to 10 parts by weight of a metal salt of fatty acid.