JPH05237453

PURPOSE:To enhance the adhesion or durability of a coating layer and to achieve the possibility of the repairing thereof by arranging a polyolefin coating layer on the surface of a steel material and applying a primer having a specific compsn. to the upper surface of the coating layer and welding both layers before applying a colored topcoat layer to the primer layer. CONSTITUTION:At the time of production, a polyolefin coating layer is arranged on the surface of a steel material for civil engineering at first and a primer having a specific compsn. is subsequently applied to the upper surface of the polyolefin coating layer. Continuously, the coated steel material is heated to the softening point of the polyolefin coating layer or higher to weld the polyolefin layer and the primer layer. Thereafter, a colored topcoat layer is applied. The primer is obtained by adding 5-70 pts.wt. of chlorosulfonated polyolefin and 2-25 pts.wt. of a vulcanizing agent to 5-50 pts.wt. of chlorinated polyolefin (a) and 5-50 pts.wt. of a graft polymer (b) of unsaturated dicarboxylic acid and an ethylene/vinyl acetate copolymer or a polymer obtained by chlorinating said graft polymer to crosslink the obtained compsn.