A polyacetal resin composition which exhibits resistance to hot water, and contains 100 parts by mass of a polyacetal resin, 1 to 100 parts by mass, inclusive, of glass fibers subjected to a surface treatment with a blocked isocyanate compound and an aminosilane coupling agent, and 0.001 to 1.0 parts by mass, inclusive, of boric acid.

The present invention relates to a method for the deactivation of an acid catalyst during the production process of a polyoxymethylene copolymer (cPOM) by adding triisopropanolamine (tris(2-hydroxypropyl)amine) to a mixture which comprises the polyoxymethylene copolymer (cPOM) and the acid catalyst.

The present invention relates to a method for the deactivation of an acid catalyst during the production process of a polyoxymethylene copolymer (cPOM) by adding triisopropanolamine (tris(2-hydroxypropyl)amine) to a mixture which comprises the polyoxymethylene copolymer (cPOM) and the acid catalyst.

Poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof are used in molding materials comprising polyoxymethylene or a copolymer containing a majority of oxymethylene units, for improving the flexural toughness of moldings formed from the molding materials.

Poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof are used in molding materials comprising polyoxymethylene or a copolymer containing a majority of oxymethylene units, for improving the flexural toughness of moldings formed from the molding materials.

A method for producing an oxymethylene copolymer which gives molded articles that are inhibited from emitting formaldehyde and can be reduced in yellowness is provided. In producing an oxymethylene copolymer, an effective polymerization initiator amount is regulated to a value within a given range, the amount being calculated from the amount of perchloric acid or a derivative thereof contained in the polymerization initiator and the amount of triethanolamine contained in all the monomers comprising trioxane and comonomers, which are starting materials for the copolymer.

A method for producing an oxymethylene copolymer which gives molded articles that are inhibited from emitting formaldehyde and can be reduced in yellowness is provided. In producing an oxymethylene copolymer, an effective polymerization initiator amount is regulated to a value within a given range, the amount being calculated from the amount of perchloric acid or a derivative thereof contained in the polymerization initiator and the amount of triethanolamine contained in all the monomers comprising trioxane and comonomers, which are starting materials for the copolymer.

The present invention addresses the problem of providing a polyacetal resin composition which can minimize degradation of a molded product produced from the acetal resin composition, when the molded product is in contact with an acidic cleaner. Said problem is solved by a polyacetal resin composition, comprising: polyacetal copolymer (A) in an amount of 100 parts by mass, wherein said polyacetal copolymer (A) has a hemiformal terminal group content of 0.8 mmol/kg or less; hindered phenol-based antioxidant (B) in an amount of 0.1 to 1.0 part by mass; and at least one selected from an oxide of magnesium or zinc or a hydroxide of magnesium or zinc (C) in an amount more than 2.0 parts by mass and 30 parts by mass or less.

The present invention addresses the problem of providing a polyacetal resin composition which can minimize degradation of a molded product produced from the acetal resin composition, when the molded product is in contact with an acidic cleaner. Said problem is solved by a polyacetal resin composition, comprising: polyacetal copolymer (A) in an amount of 100 parts by mass, wherein said polyacetal copolymer (A) has a hemiformal terminal group content of 0.8 mmol/kg or less; hindered phenol-based antioxidant (B) in an amount of 0.1 to 1.0 part by mass; and at least one selected from an oxide of magnesium or zinc or a hydroxide of magnesium or zinc (C) in an amount more than 2.0 parts by mass and 30 parts by mass or less.

An oxymethylene-copolymer manufacturing method includes: polymerizing a polymerization raw material containing trioxane and a comonomer in the presence of an acid catalyst in a quantity that is 1.010.sup.8 moles to 5.010.sup.6 moles with respect to 1 mole of trioxane; adding a hydroxylamine compound represented by general formula (1) (in the formula, R.sup.1 and R.sup.2 are, independently of each other, a hydrogen atom or an organic group having 1-20 carbon atoms) to a reaction product obtained during the polymerizing of the polymerization raw material at 50-5000 times the quantity of the acid catalyst, in terms of the molar quantity, and mixing the hydroxylamine compound with the reaction product; and for subjecting the mixture of the reaction product and the hydroxylamine compound, which is obtained during the adding of the hydroxylamine compound, to an additional melt-kneading.

##STR00001##