Patent ID: 7816433

Claim:
A polyacetal resin composition comprising: (A) 100 parts by mass of polyacetal resin having a generation amount of formaldehyde of not more than 100 ppm when heated at a temperature of 200° C. for 50 minutes under nitrogen atmosphere, and (B) 0.01 to 5 parts by mass of a hydrazide compound, represented by the following formula (3): H 2 NNHCO—R 5 —CONHNH 2 (3) wherein R 5 represents a C 2 -C 20 hydrocarbon, wherein the polyacetal resin (A) is a polyacetal copolymer obtained through a heat treatment of unstable terminal groups as defined by the following: the polyacetal copolymer is subjected to heat treatment in a molten state at a temperature in the range of from the melting point of said polyacetal copolymer to 260° C. in the presence of at least one quaternary ammonium compound represented by the formula (1) below: [R 1 R 2 R 3 R 4 N + ] n X −n (1) wherein each of R 1 , R 2 , R 3 and R 4 independently represents an unsubstituted or substituted C 1 -C 30 alkyl group, a C 6 -C 20 aryl group, an aralkyl group wherein an unsubstituted or substituted C 1 -C 30 alkyl group is substituted with at least one C 6 -C 20 aryl group, or an alkylaryl group wherein a C 6 -C 20 aryl group is substituted with at least one unsubstituted or substituted C 1 -C 30 alkyl group, wherein said unsubstituted or substituted alkyl group is linear, branched, or cyclic, and said substituted alkyl group has at least one substituent selected from the group consisting of a halogen atom, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, and an amide group, and wherein at least one hydrogen atom of each of said unsubstituted alkyl group, said aryl group, said aralkyl group, and said alkylaryl group is optionally replaced by a halogen atom; n represents an integer of from 1 to 3; and X represents a hydroxyl group, or an acid residue of a C 1 -C 20 carboxylic acid, a hydroacid excluding a hydrogen halide, an oxoacid, an inorganic thioacid or a C 1 -C 20 organic thioacid; in an amount of from 0.05 to 50 ppm by mass in terms of the amount of the nitrogen ascribed to the quaternary ammonium compound, based on the total mass of the polyacetal copolymer and the quaternary ammonium compound, wherein the amount of the nitrogen is represented by the formula (2) below: P×14/Q (2) wherein P represents the amount (ppm by mass) of the quaternary ammonium compound, based on the total mass of the polyacetal copolymer and the quaternary ammonium compound, 14 is the atomic weight of nitrogen, and Q represents the molecular weight of the quaternary ammonium compound.