| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat insulating pipe whose inner pipe is made out of a hard synthetic resin, which is easy to manufacture, excellent in quality, and has a stable structure preventing heat insulating material from being protruded or drawn out from cut-ends. SOLUTION: An inner pipe 1 is formed up by letting belt shaped hard synthetic resin material 1' in a semi-fused state be wound up in a spiral form, and a heat insulating layer 2 is formed up by letting belt shaped heat insulating material 2' made out of a foamed polyethylene resin which is non-adhesive or hardly bonded to the inner pipe 1 made out of a hard synthetic resin, be similarly wound up in a spiral form over the inner pipe 1, and concurrently, the outer and inner end parts themselves wound up in advance at the joining surface of the belt shaped heat insulating portion and the belt shaped heat insulating portion wound up later on, are mutually fused so as to be integrally bonded with each other 4 and 5, and an outer pipe 3 is formed up by letting belt shaped material 3' made out of a soft synthetic resin by wound up furthermore over the heat insulating material layer 2. |
