Polyolefin-coated steel pipe having high resistance to thermal oxidative degradation and high weatherability and a process for manufacturing the same

摘要

PCT No. PCT/JP97/03895 Sec. 371 Date Jun. 5, 1998 Sec. 102(e) Date Jun. 5, 1998 PCT Filed Oct. 27, 1997 PCT Pub. No. WO98/18619 PCT Pub. Date May 7, 1998In a polyolefin-coated steel pipe having an epoxy primer layer, a maleic anhydride-modified polyolefin layer and a polyolefin layer formed one upon another on the external surface of a steel pipe, the maleic anhydride-modified polyolefin layer contains at least three kinds of specific antioxidants, and the polyolefin layer contains those antioxidants, a specific light stabilizer and a specific inorganic pigment. A process for manufacturing it is also disclosed. The polyolefin-coated steel pipe has both a high level of resistance to deterioration by thermal oxidation and a high level of weatherability. Both of the maleic anhydride-modified polyolefin layer and the polyolefin layer are preferably of an ethylene-propylene block copolymer.