What components does the coating system of color steel coils usually include?

The coating system of color steel coils is usually divided into substrate, chemical pretreatment layer, primer layer and topcoat layer from the inside out. Some high-end products will also add a protective film/back paint layer outside the topcoat layer.
– Substrate: Mostly cold-rolled sheets or hot-dip galvanized sheets, serving as the basic load-bearing layer of color steel coils.
– Chemical Pretreatment Layer: Generally a phosphating layer or passivation layer, which improves the adhesion between the substrate and the primer and enhances rust resistance.
– Primer Layer: It plays a connecting role, further preventing rust and improving the adhesion effect of the topcoat.
– Topcoat Layer: It determines the appearance color and weather resistance of color steel coils. Common types include polyester (PE) and polyvinylidene fluoride (PVDF).