COATING TYPE CHROMATE-RESIN SOLUTION HAVING SUPERIOR WELDABILITY AND FINGER PRINTING RESISTANCE, AND METHOD FOR MANUFACTURING FINGER PRINTING RESISTANT STEEL SHEET USING THE SAME

摘要

PURPOSE: A coating type chromate-resin solution is provided which not only has stability (storage property) of a resin solution for a finger printing resistant steel sheet but also forms a chromium-resin mixed film after coating the solution on the steel sheet, and a method is provided to secure weldability and finger printing resistance of the steel sheet using the resin solution. CONSTITUTION: The coating type chromate-resin solution having superior weldability and finger printing resistance comprises a main solvent resin in which 40 to 50 wt.% of butylacrylate, 40 to 49 wt.% of methylmethacrylate and 1 to 20 wt.% of methacrylic acid are polymerized and an average particle size is 0.05 to 0.1 microns; colloidal silica coated with alumina in which a weight ratio of the main solvent resin to silica is 4:6 to 1.5:8.5; chromium aqueous solution in which a constituent ratio of trivalent chromium in 10 to 30 g/l of chromium constituent is 0.3 to 0.5 based on the total volume of chromium aqueous solution; and 0.5 to 5 g/l of N-β(aminoethyl)γ-aminopropyl trimethoxysilane coupling agent based on the total volume of chromate-resin solution. The method comprises the steps of preparing the coating type chromate-resin solution by adding a main solvent resin to a mixed solution of alumina coated colloidal silica, chromium aqueous solution and silane coupling agent; coating the chromate-resin solution on both sides of a steel sheet to be plated; and forming a chromium-resin mixed film layer comprising 30 to 50 mg/m2 and 400 to 700 mg/m2 on the steel sheet by bake drying the steel sheet at a temperature of 140 to 150 deg.C.