| 摘要 |
PROBLEM TO BE SOLVED: To provide a lightweight, fireproof double-layer pipe and its method of manufacture, with which good strength, heat insulation, and easiness to execute works. SOLUTION: A lightweight, fireproof double-layer pipe is structured so that a polyvinyl chloride pipe 2 or a connecting pipe for pipe 2 is covered with a non-combustible phenol resin foaming substance having minute projections 3 in the internal longitudinal direction in a pipe or a half-split die prepared by dividing a pipe into two segments. The foaming substance chiefly contains resor type phenol resin, foaming agent, hardening agent, hollow particulates of ceramic, glass powder, and aluminum hydroxide, wherein the hollow particulates of ceramic have a compression strength of 600kgf/cm<2> or more, a bulk specific gravity of 0.3-0.5g/cm<3> , and a melting point of 1500 deg.C or more. To these chief constituents, water and a thickening agent are added, and the obtained material is subjected to an extrusion molding or pressurized cast molding process. |
