| 摘要 |
PURPOSE:To obtain the titled steel pipe that is superior to a prior bituminous substance-coated steel pipe in adhesive strength under shear and handling durability, by sticking a specified polyolefin resin powder on the molten polyethylene coating before it is hardened after being extruded. CONSTITUTION:In coating a steel pipe by an extrusion method, before the molten polyethylene coating is hardened, the powder of a polyolefin resin (e.g., a polyolefin, a modified polyolefin, an ethylene/vinyl acetate copolymer, ethylene/ethyl acrylate copolymer, etc.) having a particle size of 28-150 mesh, a melt index of 0.1-15g/10min is stuck to its surface by spraying or the like in an amount of 25-250g/m<2> to make the surface rugged. The thus obtained steel pipe has large resistance against sliding on the outer layer of mortar, concrete, or the like, and its commodity value is retained during its transportation. |
