POLYETHYLENE COATED STEEL PIPE

摘要

PURPOSE:To enhance impact resistance and scratch resistance by successively laminating and applying a colorless polyethylene layer with specific density and a specific melt index and a crosslinked colored polyethylene layer having specific density and containing a specific wt.% of pigment to the surface of a substrate treated steel pipe through a modified polyethylene layer. CONSTITUTION:A colorless polyethylene layer 5 with density of 0.920-0.955 and a melt index of 0. 10-0.80 and an electron beam crosslinked colored polyethylene layer 7 with density of 0.930-0.945 containing 0.1-7wt.% of pigment are successively laminated to the surface of a steel pipe subjected to substrate treatment through a modified polyethylene layer 4. That is, before modified polyethylene is applied to the steel pipe, substrate treatment consisting of a chromate film 2 and an epoxy primer film 3 is applied to the steel pipe. A chromate treatment agent is applied to the surface of the steel pipe from which scale is removed by blasting treatment, pickling or degreasing using a roll or a brush and the coated steel pipe is heated and baked to form a chromate layer.