PPGI corrugated roofing sheets may age after being used for a long time or if they are not used for a long time. Why do you say that? Long-term construction or storage will inevitably be exposed to the sun. After prolonged exposure to light, aging will occur, which we cannot avoid, but we can prevent and reduce the rate of aging in advance. What should we do?
The first necessary condition for the aging or photochemical reaction of the color-coated plate is that the surface components of the ppgi corrugated roofing sheets can absorb radiation; secondly, when the radiation energy absorbed by the molecules is greater than the molecular bond energy, the color-coated sheet coating can be degraded. Because the shorter the wavelength of light, the higher the energy it contains.
According to the above theory, the aging of ppgi corrugated roofing sheets in the atmospheric environment is that the coating molecules absorb the energy of the ultraviolet light band higher than the molecular bond energy of the sunlight, which leads to the degradation of the coating molecules. With the aging of the coating film, the body of the base material is gradually lost, and the surface of the coating gradually becomes rough and loses its gloss. This loss of binder ultimately leaves more stable pigment particles, which remain on the surface of the coating film in the form of unbonded powder. This process is called chalking.
In summary, polyester ppgi corrugated roofing sheets with different coating thicknesses have great differences in aging resistance. Thin-coated color-coated sheets have poor aging resistance, and coatings with normal thickness have relatively good aging resistance.
Therefore, it is not feasible to reduce the production cost of ppgi corrugated roofing sheets by thinning the coating, which will inevitably lead to serious quality problems. At the same time, it is also proved from the side that the coating thickness is clearly indicated in the order contract of foreign color-coated sheet importers.
