| 摘要 |
PURPOSE:To obtain the titled copolymer having good thermal stability with good productivity using a simple apparatus, by copolymerizing trioxane with a specific cyclic ether, heat-treating the resultant crude oxymethylene copolymer below the melting temperature under reduced pressure and melting the heat- treated copolymer while heating in an extruder. CONSTITUTION:Trioxane is copolymerized with a cyclic ether, e.g. ethylene oxide, etc., having C-C bond in the molecule in the presence of a catalyst, e.g. boron trifluoride n-butyl etherate, etc., to give crude oxymethylene copolymer. The resultant granular or powdery crude oxymethylene copolymer is then heat- treated at a temperature 5-35 deg.C lower than the melting temperature of the copolymer under reduced pressure, fed from a raw material feed port 1 of an extruder into a melting zone (A) consisting of screw type paddles to discharge the residual trioxane in the raw material from a vent hole 2. Unstable end groups are decomposed in an extrusion shaft zone (D) consisting of kneading disk type paddles to discharge decomposition products from a vent hole 3 and the melt is extruded to afford the aimed copolymer. |
