| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce a raw material cost, inhibit toxicity, prevent chloride of lime from sticking to the inner face of a pipe, facilitate an engagement from a viewpoint of installation and make it easy to perform the extrusion molding of the pipe by forming a laminated pipe consisting of a combination of a crosslinked polyethylene pipe and a homogeneous crude polyethylene pipe and arranging the crude polyethylene pipe on the internal face part. SOLUTION: Crude polyethylene is extruded in a molten state from an extrusion machine to form a cylindrical C2, and a crosslinked polyethylene is likewiss melt extruded from another extrusion machine, In addition, the cylindrical C2 is discharged from a molding die in such a manner that the cylindrical C2 is encircled with the crosslinked polyethylene on the cylindrical C2 in a confluent part. Consequently, an interface C3 is formed between the inner face C1 of crude polyethylene and the outer face C2 of crosslinked polyethylene. In this case, however, the interface C3 is not clearly defined. Thus the raw material is less costly, and a silane compounding agent and a tin compounding agent as crosslinking agents do not bleed internally, so that this pipe does not cause a toxicity hazard. Besides, it is possible to blend the crude polyethylene with a chlorine separation inhibitor such as an antioxidant as a chloride of lime inhibitor or an ultraviolet absorbent.</p> |
