COATING COMPOSITION FOR STEEL SHEETS HAVING ZINC AND ZINC ALLOY COATING LAYER, METHOD FOR FORMING COATING LAYER USING THE COATING COMPOSITION AND STEEL SHEET HAVING THE COATING LAYER FORMED THEREOF

摘要

A coating composition for steel sheets having zinc and zinc alloy coating layer is provided to ensure excellent processability, adhesive property and film separation and to coat a coating membrane. A coating composition for steel sheets having zinc and zinc alloy coating layer comprises a hypophosphorous acid 1~30 weight%, manganese 0.1-10 weight%, polyvinyl compound 0.01~5 weight%, alcohol 5.0~20 weight%, zinc oxide and water for balance. The zinc oxide is included so that the amount of NaOH used in neutralization is 10.0 ml or less when the coating composition 50 ml is neutralized with 0.1 N NaOH. The content of free acid among the coating composition is controlled by 10.0 ml or less of NaOH used in neutralization when the coating composition 50 ml is neutralized with 0.1 N NaOH.