Provided is a method of manufacturing a polyacetal copolymer including: a step of copolymerizing 100 parts by mass of trioxane (A), 0.05 to 5 parts by mass of a cyclic acetal compound (B), and 0.001 to 1 parts by mass of an aliphatic glycidyl ether compound (C) having a chlorine content of 1 to 500 mass ppm, in the presence of a linear formal compound (D) as a molecular weight regulator, in which in the step, when a total mass (g) of the trioxane (A), the compound (B), and the compound (C) is “a”, a molar number of the linear formal compound (D) is “b”, and total molar numbers of water and methanol contained in the trioxane (A), the compound (B), and the compound (C) are respectively “c” and “d”, setting is performed to satisfy (b+c+d)/a=1.5 to 7 μmol/g.

Provided is a method of manufacturing a polyacetal copolymer including: a step of copolymerizing 100 parts by mass of trioxane (A), 0.05 to 5 parts by mass of a cyclic acetal compound (B), and 0.001 to 1 parts by mass of an aliphatic glycidyl ether compound (C) having a chlorine content of 1 to 500 mass ppm, in the presence of a linear formal compound (D) as a molecular weight regulator, in which in the step, when a total mass (g) of the trioxane (A), the compound (B), and the compound (C) is “a”, a molar number of the linear formal compound (D) is “b”, and total molar numbers of water and methanol contained in the trioxane (A), the compound (B), and the compound (C) are respectively “c” and “d”, setting is performed to satisfy (b+c+d)/a=1.5 to 7 μmol/g.

The present invention is to provide a process for producing an oxymethylene copolymer, in which deteriorate due to oxidation hardly occurs, an amount of formaldehyde generated from the product when stored for a long time under environment of high temperature and high humidity is reduced, and occurrence of mold deposit during molding is small. A process for producing an oxymethylene copolymer includes Step 1 of polymerizing polymer raw materials containing trioxane and a comonomer in the presence of a specific amount of an acid catalyst, Step 2 of adding a hydroxylamine compound represented by the following general formula (1): ##STR00001##
to a product obtained in the Step 1 in an amount of 1 to 20-fold mol based on an amount of the acid catalyst and mixing these, and
Step 3 of further melting and kneading a mixture of the product and the hydroxylamine compound obtained in the Step 2.

The present invention is to provide a process for producing an oxymethylene copolymer, in which deteriorate due to oxidation hardly occurs, an amount of formaldehyde generated from the product when stored for a long time under environment of high temperature and high humidity is reduced, and occurrence of mold deposit during molding is small. A process for producing an oxymethylene copolymer includes Step 1 of polymerizing polymer raw materials containing trioxane and a comonomer in the presence of a specific amount of an acid catalyst, Step 2 of adding a hydroxylamine compound represented by the following general formula (1): ##STR00001##
to a product obtained in the Step 1 in an amount of 1 to 20-fold mol based on an amount of the acid catalyst and mixing these, and
Step 3 of further melting and kneading a mixture of the product and the hydroxylamine compound obtained in the Step 2.

A method of producing dimethoxymethane oligomers (DMMn), the method comprising: reacting a formaldehyde source and dimethoxymethane monomer (DMM1) in the presence of an acidic catalyst to produce a reaction effluent comprising DMMn and unreacted DMM1; and separating, from the reaction effluent, DMM1-2 including unreacted DMM1 and DMMn having a chain length n equal to 2 (DMM2), dimethoxymethane oligomers having a chain length n in the range of from 2-5 (DMM2-5), dimethoxymethane oligomers having a chain length n of ≥5 (DMM5+), or a combination thereof, wherein the separating comprises distillation in the presence of at least one alcohol, a distillate fuel, or both.

A method of producing dimethoxymethane oligomers (DMMn), the method comprising: reacting a formaldehyde source and dimethoxymethane monomer (DMM1) in the presence of an acidic catalyst to produce a reaction effluent comprising DMMn and unreacted DMM1; and separating, from the reaction effluent, DMM1-2 including unreacted DMM1 and DMMn having a chain length n equal to 2 (DMM2), dimethoxymethane oligomers having a chain length n in the range of from 2-5 (DMM2-5), dimethoxymethane oligomers having a chain length n of ≥5 (DMM5+), or a combination thereof, wherein the separating comprises distillation in the presence of at least one alcohol, a distillate fuel, or both.

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.