The first prerequisite for the aging or photochemical reaction of the color steel coil is that the surface composition of the color steel coil can digest and absorb radiation; secondly, when the radiant energy absorbed by the digestion and absorption of the molecular structure exceeds the bond energy of the molecular structure, the color steel coil coating can be dissolved. Because the light source has fewer wavelengths, the more kinetic energy it contains.
According to this basic theory, the embrittlement of color steel coils caused by air pollution is that the molecular structure of the coating digests and absorbs the kinetic energy of the ultraviolet wavelength band higher than the bond energy of its molecular structure in natural light, resulting in the dissolution of the molecular structure of the coating. With the aging of the polyurethane coating, the base material itself is gradually lost, and the surface of the coating layer gradually becomes rough and loses its luster. This type of absence of base material ends up leaving relatively smooth color paste bodies, which are left in the form of an unbonded powder to the surface of the polyurethane coating, a process known as delamination.
In general, polyester color steel coils with different coating thicknesses have great differences in anti-aging properties. The anti-aging properties of thin-coated color steel coils are weak, and the anti-aging properties of all normal thin-thickness coatings are relatively good.
