Polyolefin-covered steel pipe possessing excellent resistances to thermally oxidative deterioration and weathering and process for manufacturing the same

摘要

A polyolefin-covered steel pipe comprising a steel pipe and an epoxy primer layer, a maleic anhydride-modified polyolefin layer, and a polyolefin layer laminated in that order on the circumferential surface of the steel pipe, wherein the maleic anhydride-modifed polyolefin layer contains at least three predetermined antioxidants, the polyolefin layer contains the above antioxidants in combination with predetermined photostabilizer and inorganic pigment. The steel pipe combines high resistance to thermally oxidative deterioration with high weathering resistance. It is preferable to prepare both the maleic anhydride-modified polyolefin layer and the polyolefin layer from an ethylene/propylene block copolymer.