PREPARATION OF CROSSLINKED POLYETHYLENE PIPE

摘要

PURPOSE:To increase a crosslinking degree by reacting a compounded composition wherein a radical generating agent and a silane compound are added to specific powdery polyethylene in specific amounts and the ratio of silane compound/radical generating agent is specified under heating and extruding the same into a pipe to coat the surface of an extruded molded body with polyolefin containing a siloxane condensing catalyst to bring the polyolefin into contact with moisture. CONSTITUTION:0.15 - 0.50 pts.wt. of a radical generating agent and 1.5 - 15 pts.wt. of a silane compound are added to 100 pts.wt. of powdery polyethylene wherein the number of double bonds per 1,000 carbon atoms is 0.5 or more and a melt index is 1.0 g/10 min or less so as to set the ratio of silane compound/radical generating agent to 10 - 100 to prepare a compounded composition. This composition is reacted in an extruder under heating to extrude the reaction product into a pipe. At the same time, polyolefin containing a siloxane condensing catalyst is extruded by using a sub-extruder in the crosshead part of the extruder to coat the surface of the extruded molded body and the extruded molded body is brought into contact with moisture.