Patent ID: 7893140
Filing Date: 2011-02-22
Classification: C08K,C08L

Abstract:
1. A polyacetal resin composition which comprises a blend of: (A) 100 parts by weight of a polyacetal copolymer having 1.0 mmol/kg or smaller quantity of a hemiformal terminal group, 2.0 mmol/kg or smaller quantity of a formyl terminal group, and 0.5% by weight or smaller quantity of unstable terminal groups which decompose in response to exposure to heat and a base to form formaldehyde; (B) 0.03 to 0.30 parts by weight of a hindered phenol-based antioxidant; (C) 0.05 to 0.8 parts by weight of at least one compound selected from the group consisting of (c-1) a guanamine compound and (c-2) a hydrazide compound; (D) 0.2 to 1 part by weight of at least one hindered amine stabilizer selected from the group consisting of tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butane tetracarboxylate, condensation products of 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β,β,β′,β′-tetramethyl-3,9-(2,4,8,10-tetraoxaspiro[5,5]undecane)-diethanol; and polymerization products of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol; and (E) 0.2 to 1 part by weight of a UV absorber, wherein the hindered phenol-based antioxidant (B) and the hindered amine stabilizer (D) are present in amounts to achieve a mixing ratio (B/D) within the range of 0.03 to 0.5, and wherein the hindered amine stabilizer (D) and the UV absorber (E) are present in amounts to achieve a mixing ratio (D/E) within the range of 0.5 to 2.0, and wherein the total amount (D+E) of the hindered amine stabilizer (D) and the UV absorber (E) is within the range of 0.5 to 1.5 parts by weight.