The invention provides an antimicrobial fiber which exhibits excellent antimicrobial properties even without the addition of antimicrobial agents and can remain antimicrobial even after repeated washing. The antimicrobial fiber comprises a fiber having on a surface thereof a polyacetal copolymer (X) containing oxyalkylene groups, the molar amount of oxyalkylene groups in the polyacetal copolymer (X) being 0.2 to 5 mol % relative to the total of the molar amount of oxymethylene groups and the molar amount of oxyalkylene groups.

The present invention provides a trioxane composition which comprises trioxane as a main component, an antioxidant, and at least one alkaline organic compound selected from the group consisting of an amine compound having an alcoholic hydroxy group in the molecule thereof, a thiocarbamate compound, and an organophosphorus compound, wherein the amount of the alkaline organic compound contained is 0.01 to 10 ppm, based on the trioxane, and wherein the trioxane composition is a liquid.

The present invention provides a trioxane composition which comprises trioxane as a main component, an antioxidant, and at least one alkaline organic compound selected from the group consisting of an amine compound having an alcoholic hydroxy group in the molecule thereof, a thiocarbamate compound, and an organophosphorus compound, wherein the amount of the alkaline organic compound contained is 0.01 to 10 ppm, based on the trioxane, and wherein the trioxane composition is a liquid.

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 high-quality polyacetal copolymer produced by a simple process in an economical manner. The process includes supplying a raw material including trioxane and the like to a reaction device; setting the polymerization environmental temperature to no more than 100 C. until the reaction device conversion rate becomes 0.5, and then carrying out further polymerization; vaporizing and separating unreacted monomers from the reaction mixture at an environmental temperature of at least 115 C. and less than 140 C.; supplying the separated monomers to the raw material supply; and recovering the polyacetal copolymer from the reaction mixture.

A high-quality polyacetal copolymer produced by a simple process in an economical manner. The process includes supplying a raw material including trioxane and the like to a reaction device; setting the polymerization environmental temperature to no more than 100 C. until the reaction device conversion rate becomes 0.5, and then carrying out further polymerization; vaporizing and separating unreacted monomers from the reaction mixture at an environmental temperature of at least 115 C. and less than 140 C.; supplying the separated monomers to the raw material supply; and recovering the polyacetal copolymer from the reaction mixture.