MANUFACTURE OF ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE PIPE AND PIPE MOLDING DIE

摘要

PURPOSE:To obtain the pipe with excellent accuracy of thickness uniformity by a method wherein fused ultra-high-molecular-weight polyethylene is heated and compressed between a spider die and the inlet of a heating die and fusion- welded while being lowered its temperature progressively within a specified temperature range and then cooled and set up. CONSTITUTION:An ultra-high-molecular-weight polyethylene, the intrinsic viscosity of which measure at 135 deg.C in decalin solution is 10dl/g or more, is fused in a screw extruder and dispersed by a breaker plate 1 and then heated and compressed between the spider die 2 and the inlet of the heating die 5 and at the same time adjusted the thickness uniformity and, after that, fusion-welded while being lowered its temperature progressively within 250-150 deg.C in the heating die 5 and then cooled and set up while being lowered its temperature progressively within the range from 100 deg.C to normal temperature in a taper type cooling and sizing die 6 in order to manufacture the ultra-high-molecular-weight polyethylene pipe. The surface texture of the pipe results to be fine at its inside and outside and the variation of the thickness of the pipe small.