With the rapid development of national economy, metal powder coatings are increasingly applied in outdoor. As a protective and decorative powder coating, its weather resistance and durability has also aroused more and more attention, especially for the coating of ceiling, wall panels, drinking fountains, air conditioners, washing machines and aluminum. They will have a series of changes in natural environment. Its specific performances are glossy declining of bronze powder (FCu 663), dim color and the rust or cracks on coating surface. Then the chalking emerges.

Coating of metal powder coatings with time, its performance gradually reduce the phenomenon known as aging; in the natural environment, the metal powder coating is surrounded by natural factors such as sun, rain, oxidation, hot and cold change and microorganisms. The role of the aging phenomenon is known as natural aging. Powder coatings to inhibit or delay the natural aging ability known as resistance to natural aging, referred to as the resistance to aging, also known as weathering.

Metal powder coating weatherability of many factors, including resins, hardeners, fillers and other additives, structure and performance of internal factors; and the role of sunlight, atmospheric composition, humidity, temperature changes and other natural factors. UV radiation is the main reason for the natural aging of the metal powder coating, and oxygen in the atmosphere is an important factor in the promotion of natural aging. The role of ultraviolet light and oxygen, causing the metal powder coating auto-oxidation reaction, i.e. oxidation chain reaction, so that the powder coating degradation. Water and heat accelerate this reaction, plays a role photooxidation. Contaminated atmosphere contains trace impurities in the fused ring aromatic compounds and powder raw materials, oxidative degradation of the metal powder coating light sensitive agent. A combination of these reactions and the influence of aging on the powder coating, with the different environment, and also with the differences in the powder coating chemical composition and physical structure is different, resulting in a metal powder coating weathering vary greatly. Therefore, the influence of various factors can not be ignored only by understanding the various factors for powder coatings is how it works, to seize the main contradiction in order to find out to improve their weather resistance countermeasures.

Now the international promotion of two weathering test and evaluation methods: natural exposure and artificial accelerated aging test, and stressed that the two test methods to combine into account, in order to draw more reliable conclusions. First, choose light stabilizers according to the characteristics of the metal powder, and pay attention to the temperature of the light stabilizer; second, to control the amount of light stabilizers, not the more the better. Third, the more effective use complex than a single; in the selection of light stabilizers to consider the synergies with other additives.

Research of weathering of metal powder coating is sill at initial stage. Although China is big painting country, it is still far behind western countries. So the more in-depth study and practice of weathering metal powder coating will be improved continuously with social development, technological progress and development of new materials. Adding light stabilizer is an easy and effective way to improve the weatherability of metal powder coating.Source:http://www.mhcmp.com