Prepainted steel coil coating is mainly classified as two parts. One is Primer coating, the other one is finish coating.
The classicisation of the primer includes epoxy, polyester, acrylic acid, polyurethane, etc.
Usually speaking, the chosen of the primer shall be matched with the end usage, environment condition, processing stage and finish coat. The thickness of the primer is usually 5~7 um.
Among all the ingredients of coating, resin and pigment mainly effect for duration. The primers usually is polyester (PE), silicon modified polyester(SMP), Poly Vinylidene Fluoride (PVDF), High Durability Polyurethane(HDP), etc.