| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To obtain an ethylene polymer for a pipe excellent in moldability and particularly excellent in long-life property, and to provide a pipe molded product made of the ethylene polymer. <P>SOLUTION: The ethylene polymer for the pipe has an intrinsic viscosity [η] (dl/g) of 2.7-4.1 as measured in decalin at 135°C, a density (d) (kg/m<SP>3</SP>) of 952-962 kg/m<SP>3</SP>for a sample which is straightly cooled down to room temperature in one hour after one hour annealing at 120°C as measured using a density gradient tube, a weight-average molecular weight(Mw)/number-average molecular weight (Mn) ratio of at least 11 and at most 50 as measured by GPC (gel permeation chromatography), and the actual stress (S) (MPa) of 19.4-27.2 when the number of cycles until breakage in the tensile fatigue characteristics is measured at 23°C is 10,000. The pipe is made of the ethylene polymer. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
