Coating Composition for Pre-Sealed Steel Sheet And Preparing Method of Pre-Sealed Steel Sheet Having Improved Corrosion Resistance Electro-Painting Properties and Weldability

摘要

PURPOSE: A resin composition for a pre-sealed steel sheet and a method for preparing a pre-sealed steel sheet by using the composition are provided, to improve corrosion resistance, electrodepositing property and weldability. CONSTITUTION: The resin composition comprises an epoxy resin having a number average molecular weight of 3,000-7,000 dispersed or emulsified in water; 5-20 phr of a melamine resin; 13-30 phr of a water-dispersive colloidal silica; 1-5 phr of a wax; and 80-300 phr of at least one metal powder having a particle size of 0.5-4 mm and selected from the group consisting of Al, Cu, Ni, Zn, Fe2P, Fe, Mn, Co, Ti and Sn. Preferably the wax is selected from the group consisting of polyolefin-based waxes, carnauba waxes, Teflon-based waxes and silicone-based waxes; and the metal powder is needle-shaped or plate-shape one having a length of major axis of 0.5-4 mm.