| 摘要 |
<P>PROBLEM TO BE SOLVED: To manufacture a resin pipe having a heat insulating warmth preserving capacity over a long period of time at a low cost. <P>SOLUTION: A resin flow channel 2x, to which an annular bridge 6 is arranged, is filled with a molten foamable vinyl chloride resin through an extruder and the molten resin into a pipe shape while once branched into an inner peripheral side and an outer peripheral side by the bridge 6 before allowed to meet with each other. Then, the inner peripheral surface side and outer peripheral surface side of the molten resin after meeting are cooled to form substantially non-foamed skin layers and the whole is cooled while foaming the molten resin between the inner peripheral surface side skin layer and the outer peripheral surface side skin layer. By this constitution, the resin pipe having the skin layers respectively formed to the inner and outer peripheral surfaces of its foamed layer comprising a vinyl chloride resin foam is molded. <P>COPYRIGHT: (C)2008,JPO&INPIT |
