PURPOSE: To improve adhesion, shock resistance, water resistance and heat deterioration resistance of a coating layer, by a method wherein an adhesive polyethylene coating layer and polyethylene pellet layer are formed after formation of a foundation treatment layer by applying chemical conversion treatment and/or primer coating to a Zn plated layer of a steel material.
CONSTITUTION: A chemical conversion treatment layer and/or a primer layer are provided as a foundation treatment layer 3 on a Zn plated steel material having a Zn plated layer 2 on the outer surface of a foundation steel material 1. An adhesive polyethylene layer 4 is formed on the same by sticking and fusing a polyethylene powdery body onto the same. Then the same is put into a post-heating furnace to smoothen the surface of the polyethylene by fusing the polyethylene powdery body sufficiently to the same. Polyethylene pellets are sprayed on the polyethylene in a molten state and the pellets are stuck to the polyethylene. Reheating is performed after surplus polyethylene pellets have been shaken off. The adhesive polyethylene layer 4 of a lower layer and pellets are fused together, the pellets turn disklike and fused in all directions. After reheating, a polyethylene pellet layer 5 is formed by letting stand to cooling.
MUKOHARA FUMINORI
TAKEUCHI HIDEO
