| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyacetal copolymer excellent in toughness, rigidity, and heat resistance by thermally treating a linear polyacetal copolymer at a specified temperature in the presence of a specified amount of a quaternary ammonium compound to decompose and remove unstable terminal moieties and impart a specified MFI to the copolymer. SOLUTION: A polyacetal copolymer is melted and thermally treated at its melting point or higher but not higher than 260 deg.C in the presence of a quaternary ammonium compound of the formula: [R1R2R3R4N+]nX-n in an amount of 0.05-50 ppm (in terms of the amount of N represented by the formula: P×14/Q) based on the sum of the salt and the copolymer to thereby decompose and remove unstable terminal moieties and impart an MFI (190 deg.C, 2169 g) of 1.0 g/10 min to the copolymer. In the formulas, R1 to R4 are each 1-30C alkyl, 6-20C aryl, or the like; n is 1-3; X is OH, a 1-20C carboxylic acid group, or the like; P is the amount (ppm) of the quaternary ammonium compound based on the sum of it and the oxymethylene copolymer; 14 is the atomic wt. of N; and Q is the mol.wt. of the quaternary ammonium compound. |
