| 摘要 |
PROBLEM TO BE SOLVED: To obtain a compsn. capable of substrate treatment for improving the adhesion to a coating film, coin scratch resistance and corrosion resistance by allowing it to contain a trivalent chromium compd. sol, hexavalent chromium ions, water base resin emulsion and rust preventive pigment as indispensable components and specifying the pH therein. SOLUTION: The pH is 2.5 to 12. Preferably, the weight ratio of the solid contents between the whole chromium/the resin emulsion is controlled to the range of 1/20 to 1/2, and the weight ratio of the solid contents between the trivalent chromium compd. sol/the rust preventive pigment is controlled to the range of 1/5 to 10/1. The rust preventive pigment is preferably selected from chromate rust preventive pigment (strontium chromate, zinc chromate or the like) and non-chromate rust preventive pigment (phosphate rust preventive pigment, molybdate rust preventive pigment or the like), the compsn. contains a silica sol, an alumina sol, a titania sol or the like, and the water base resin emulsion is preferably selected from urethane resins, epoxy resins, acrylic resins or the like. A colored steel sheet free from the need of chemical conversion treatment can be produced.
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