RESIN CHROMATE BATH AND SURFACE TREATED STEEL SHEET

摘要

PROBLEM TO BE SOLVED: To provide a resin chromate bath having an excellent bath life and to produce a surface treated steel sheet having films provided with excellent bare corrosion resistance, coating material adhesion property and chromium elution resistance. SOLUTION: This resin chromate bath consists of an aq. soln. which contains 40 to 65wt.% chromic acid having a chromium reduction rate of [tervalent Cr/(tervalent Cr + hexad Cr)×100], phosphoric acid and resin and has a phosphoric acid/resin (weight) ratio of 0.3 to 1.0. The surface treated steel sheet has this resin chromate films formed from the bath on a cold rolled steel sheet or Zn or Zn alloy plated steel sheet.