Corrosion begins from the exposed surface and damages the material layer by layer. A layer of coating will be more protective. It can keep the base metal from corrosion, chemical damage, and UV light to prolong its service life. At the same time, it can make the metal surface smooth and good-looking. That's why the coating process is necessary.
For example, color coated steel (PPGI and PPGL) consists of zinc coating or Al-Zn coating, prime coating, and finish coating. Commonly, both two sides are coated. Compared to the top coating, the coating for the back side is called back coating. Let's review the function of each layer of paint.
Color Coated Steel Structure
Types of Paints
The commonly-used paints are PE, SMP, PVDF, HDP. Below is a short introduction to the paint.
PE (polyethylene)
It has good comprehensive performance and its good weather ability meets the basic requirements of exterior building. It is usually applied to the range of industrial buildings, commercial buildings such as roofs, and external walls.
SMP (Silicone Modified Polyester)
It has ultra-weathering pigments to ensure the permanent brightness of the color. Moreover, the SMP paint provides a special silicone structure to enhance the hardness of coating which can not only increase wear resistance and metal scratching but also withstand the deep processing of stamping.
PVDF (polyvinylidene fluoride)
The PVDF paint has more than 70% of the polyvinylidene fluoride content, It gives the coating good weather resistance, acid and alkali, and environmental pollution performance. The PVDF paint uses advanced inorganic ceramic pigments to block the UV and maintain a gloss color for coating.
HDP (High durability polyester)
HDP has more colors than PVDF. Due to this paint's special polyester structure and good hydrolysis resistance, HDP also has excellent chemical resistance and durability.
You can choose the paints according to the intended uses, service environment, your budget, the surroundings, etc.