| 摘要 |
<p>A method of stabilizing the molecular ends of an oxymethylene copolymer with the use of an extruder comprising a casing provided with feed and delivery ports and at least two longitudinally extending rotating shafts, the extruder being provided, in the inside, with a melting zone, an end-stabilizing reaction zone and a devolatilizing zone in this order from the feed port toward the delivery port and further provided, in the area having a length of 2-15D (D being the inner diameter of the casing) in the end-stabilizing reaction zone, with a number of kneading elements having a thickness of 0.1-0.3D fixed to the rotating shafts in the longitudinal direction thereof in order to knead a crude oxymethylene copolymer in a molten state in the presence of a basic substance in the above reaction zone to thereby decompose the unstable molecular ends of the crude copolymer. The method enables the molecular ends of a crude oxymethylene copolymer to be stabilized in a short time efficiently and substantially completely.</p> |
