Pre-painted galvanized steel coil (PPGI) is a composite steel product made by using hot-dip galvanized steel coil as the substrate, which undergoes surface pretreatment, followed by continuous roller coating with organic paint and baking curing. Due to its advantages of corrosion resistance, weather resistance, and decorative properties, it is widely used in construction, home appliances, rolling shutter doors, billboards, and other fields, serving as the main material for building envelopes and home appliance exterior trim.