| 摘要 |
PROBLEM TO BE SOLVED: To improve an earthquake resistance while maintaining deformation followability by using a metallocene compound containing a transition metal as a polymerization catalyst. SOLUTION: After a high density polyethylene compound is, for example, introduced into an extruder so that a billet 2 is manufactured, the billet 2 is biaxially oriented simultaneously in circumferential and axial directions by a radially enlarged structure of a mandrel 12 and a die 13, and a biaxially oriented polyethylene resin tube is formed. At this time, at least 40 wt.% of the resin of the tube is the high density polyethylene compound manufactured by polymerizing by using a metallocene catalyst. Accordingly, even if a large force is applied, a crack scarcely occurs. The billet 2 is oriented in axial or circumferential direction, and hence a strength of the tube can be enhanced. ESCR characteristics, a tensile breaking elongation and the like are enhanced, and deformation followability can be improved. |
