Method for producing an oxymethylene copolymer

Abstract

Provided is a method for producing an oxymethylene copolymer having excellent extrusion moldability and reduced voids in a molded article without lowering the inherent performance of an oxymethylene copolymer. Provided is a method for producing an oxymethylene copolymer, including: a step for copolymerizing a monomer raw material containing trioxane and 5-7 mass % of 1,3-dioxolane relative to the trioxane, in the presence of 0.025-0.07 mmol of boron trifluoride per mol of trioxane and 0.006-2.0 mass % of sterically hindered phenol relative to the trioxane; a step for adding a polymerization terminator to the reaction system when the polymerization yield of this copolymer has reached 92% or higher, and terminating polymerization; and a thermal stabilization step for heating and melting the crude oxymethylene copolymer in the presence of 0.05-5 mass % of an antioxidant and 0.005-5 mass % of a nitrogen-containing compound relative to the crude oxymethylene copolymer.

Dependencies are inferred from the claim text.