| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a piping material which is classified as PE 100 according to the ISO 9080 standard, requires a 100-year guarantee, is excellent in long-term properties under a high temperature acceleration condition, rigidity, elongation properties, impact resistance and moldability and furthermore is excellent in long-life reinforcement and surface properties of the SCG (slow crack growth), and to provide a pipe and a joint particularly.SOLUTION: The piping material contains a polyethylene resin composition which contains an ethylene homopolymer and/or a copolymer of ethylene andα-olefin having 3-20 carbon atoms and satisfies the following conditions (1)-(4). The condition (1) is that the density thereof is 948-952 kg/m. The condition (2) is that the melt flow rate (code T) thereof is equal to or higher than 0.15 g/10 minutes and lower than 0.30 g/10 minutes. The condition (3) is that the molecular weight distribution thereof is equal to or wider than 15 and narrower than 25. The condition (4) is that when a hot internal pressure creep test to be stipulated in ISO 9080 is applied thereto at 20°C and a plotted line of logarithms of rupture times versus those of hoop pressures is drawn, an inclination ratio of the plotted line satisfies the following relationship. (the inclination before 1,000 hours)/(that after 1,000 hours)>1.5.</p> |
