| 摘要 |
<p>PROBLEM TO BE SOLVED: To cope with consumption of an antioxidant in fusing so as to secure heat resistance in a fused part after fusion by setting concentration of an antioxidant in an area including a resistance heating wire embedded in a connection pipe coupling part in a joint main body to be higher than that of an antioxidant contained in the area other than this area. SOLUTION: In a fusion joint 2, a plurality of resistance electrical heating wires 4, to which electricity can be supplied via respective terminals 9a, 9b, are embedded in a connection pipe coupling part of a joint main body 1 made of a thermoplastic resin. Concentration of an antioxidant in an area 11 affected by influence of heat from the resistance heating wire 4 in a fusion time is set to be higher than that of an antioxidant in an area 12 other than the area 11. For example, the resistance heating wire 4 covered with a covering agent made of a polyethylene resin containing an antioxidant is wound on a cylindrical core die and mounted to a metal die, and then, injection molding of polyethylene resin containing an antioxidant with a selected concentration is carried out. In this way, heat resistance can be secured after an antioxidant is consumed by heat in a fusion time.</p> |
