Prepainted steel coil or PPGI PPGL steel coil is coated with organic layer, which provides higher anti-corrosion property and a longer lifespan than that of galvanized steel sheets. The base metals for prepainted steel sheet consist of cold rolled steel, hot dip galvanized steel, gavalume steel and electro-galvanized steel. The finish coats of prepainted steel sheets can be classified into groups as follows: polyester (PE), silicon modified polyesters (SMP), high-durability polyester (HDP) and polyvinylidene fluoride (PVDF), etc.