| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a multi-coated steel pipe coated with a protection layer having proper adhesiveness and peeling performance at the external face of an anticorrosion layer which is coated on the external surface of the steel pipe. <P>SOLUTION: In the multi-coated steel pipe coated with the anticorrosion layer composed of a polyethylene resin layer and a protection layer composed of a polypropylene resin layer as an upper layer of the anticorrosion layer at the external surface of the steel pipe which is a base material, a polypropylene resin forming the protection layer is used as a copolymer resin containing 19 to 23 mol% of an ethylene component, a melt flow rate is set as 0.53 to 0.60g/10min, shearing viscosity at a temperature of 280°C is set as 1.7×10<SP POS="POST">3</SP>to 2.0×10<SP POS="POST">3</SP>Pa s when measured at a shearing speed of 10/sec, and set as 5.3×10<SP POS="POST">2</SP>to 6.0×10<SP POS="POST">2</SP>Pa s when measured at a shearing speed of 100/sec. <P>COPYRIGHT: (C)2012,JPO&INPIT |
