Method for producing a stabilized oxymethylene copolymer

Abstract

The present invention provides a method for producing an oxymethylene copolymer, which comprises: copolymerizing trioxane and a cyclic ether and/or a cyclic formal in the presence of at least one selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and a coordination compound of an organic compound having an oxygen or a sulphur atom with boron trifluoride, volatilizing the residual polymerization catalyst to decrease its amount, by heating the obtained oxymethylene copolymer in an atmosphere of inert gas at or below its melting point, and/or reducing the pressure, without conducting any operation of deactivating the residual polymerization catalyst before volatilizing the residual polymerization catalyst, and stabilizing terminal moities of the oxymethylene copolymer after deactivating residual catalyst or stabilizing terminal moieties of the oxymethylene copolymer directly. According to the present invention, an oxymethylene copolymer having excellent heat stability, which causes little smell of formaldehyde in melt molding, can be obtained by reducing the amount of residual polymerization catalyst in the oxymethylene copolymer.

Dependencies are inferred from the claim text.