Pretreatment of zinc plated steel plate substrate for coating

PURPOSE:Pretreatment of zinc plated steel plate substrate forcoating to eliminate the formation of roping, etc. by coating the surface of zinc plated steel plate with a specific surface treating agent by using applicator roll having specific hardness and drying the steel plate. CONSTITUTION:The surface of zinc plated steel plate is coated with a water coating type metal surface treating agent containing aqueous resin and insoluble white corbon or comentional surface treating agent by natural roll coating method by using an applicator roll having a hardness of 40 to 60 degree finished with sand paper of 60 to 240 mesh or with a material having almost the same surface abrasive degree as the sand paper, and then dried. The steel plate thus treated is free from problems such as roping after coating, and has excellent paint-adhesion property, anticorrosion property, etc. This process does not produce the treated waste water, sludge, etc, and contributes to prevent environmental pollution. The reduction in the cost of treatment becomes possible.