COMPOSITION FOR CR-FREE COATING MATERIAL AND SURFACE TREATED STEEL SHEET WITH SUPERIOR BLACKENING-RESISTANCE AND CORROSION-RESISTANCE

摘要

Provided is a chrome-free coating composition with excellent blackening resistance and corrosion resistance, which is composed of: 20-70 wt% of a silane-modified water-dispersible urethane resin; 0.5-5 wt% of a hardening agent; 0.5-5 wt% of a blackening preventing agent; 0.5-5 wt% of an anti-rust agent; 0.5-5 wt% of a lubricant; and a residual solvent. Thus, it is possible to secure processability and improve blackening resistance, corrosion resistance, alkali resistance, solvent resistance, and fingerprint resistance of magnesium-containing steel sheets.