METHOD FOR TWO-LAYER EXTRUSION MOLDING FOR PROFILE RESIN-COATED STEEL TUBE AND TWO-LAYER-COATED PROFILE RESIN-COATED STEEL TUBE

摘要

PROBLEM TO BE SOLVED: To provide a method for two-layer extrusion molding of an inner layer resin adhering and covering an outer peripheral surface of a thin steel tube and an outer layer resin covering a part or an overall surface of the inner layer resin as a thin and uniform coating layer and two-layer-coated profile resin-coated steel tube. SOLUTION: A flat surface part, a rib or the like in a tubular axial direction is integrally extrusion molded in a size obtained by subtracting a thickness of coating of the outer layer resin by the inner layer resin adhering and covering the outer peripheral surface of the thin steel tube, and the outer layer resin is extrusion molded as a thin uniform coating layer on a site necessary in function of the surface of the inner layer resin or the overall part. As the inner layer resin, a recycled resin of an ABS resin, an ABS, an AAS, an AES or the like or a resin obtained by mixing their recycled resins with a novel ABS resin is used. As the outer layer resin, a novel AAS, the AES, an urethane, a polycarbonate or an acrylic resin is used.