| 摘要 |
PURPOSE: A high lubrication chromium-free finger printing resistant steel sheet is provided which improves wettability with resin by treating the phosphate surface with weak acid (a mixture of hydrofluoric acid, nitric acid and hydrochloric acid) after improving corrosion resistance by micronizing the structure of a phosphate film through surface cleaning. CONSTITUTION: The high lubrication chromium-free finger printing resistant steel sheet is characterized in that it is manufactured by refining phosphate structure by adding chelate compound to the phosphate solution in surface treatment process for treating 1.0 to 2.5 g/m¬2 of phosphate solution onto electrogalvanized steel, increasing resin wettability by adding about 1.0 to 3.0 g/L of starch to the phosphate solution, etching the surface of the phosphate solution treated electrogalvanized steel with a weak acidic solution prepared by mixing one or more acids selected from the group consisting of hydrofluoric acid, nitric acid and hydrochloric acid, and baking the high lubrication finger printing resistant resin film to a drying temperature of 75 to 90 deg.C after coating a thin film of urethane modified acryl copolymer resin on the etched phosphate film coated electrogalvanized steel in a resin adherence amount of 800 to 1500 mm/m¬2, wherein the urethane modified acryl copolymer resin is prepared by synthesizing 2 to 40 wt.% of ethylenic unsaturated monomer enabling radical polymerization, 1 to 10 wt.% of urethane prepolymer which is chain extended to a low molecular compound having two or more active hydrogens obtained by reacting polyol with polyisocyanate, 4 to 15 wt.% of polypropylene based wax, 10 to 20 wt.% of silica, 2 to 10 wt.% of ethanol or isopropyl alcohol, 0.1 to 5 wt.% of a polymerization initiator for ethylenic monomer which is capable of radical polymerization and selected from t-butyl perbenzoate, lauryl perbenzoate, benzoyl peroxide, t-butylhydroperoxide, azobisisobutyronitrile and azobis dimethylbutyronitrile, and 2 to 15 wt.% of carbodiimide added to polymer for improving curing reaction.
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