Light resistance and weather resistance of pigments

The light resistance and weather resistance of pigments are important indicators of the application performance of the scale. Light fastness mainly refers to the ability to resist sunlight (especially ultraviolet rays); weather resistance refers to the ability to resist atmospheric erosion (including sunlight). Light fastness level 8 is better, level 1 is the worst; weather resistance level 5 is better, level 1 is the worst.

Pigments are exposed to sunlight, rain, etc. for a long time, and their chemical composition will change to some extent (photochemical reaction ) . Darken (darker). The main factors that determine the light resistance and weather resistance of pigments are the chemical composition and structure of the pigments, and also have a certain relationship with the surrounding medium, pigment particle size distribution and surface treatment.

Generally speaking, the light fastness and weather fastness of inorganic pigments are better than organic pigments, but not very. There are also some inorganic pigments whose chemical composition changes after being colored by light, and the color will change obviously. For example: the light resistance of Minghuang and Yaoguohong is only 4-5, and the weather resistance is 3. The light resistance of Minghuang and aluminum pick red after surface coating treatment can reach 8, and the weather resistance is 4-4. Level 5. Some polycyclic organic pigments have excellent light resistance and weather resistance, which are even higher than most inorganic pigments, such as guanidine red (PR122), DPP red (PR 254), onionyl red (PR168), isophthalic acid The light can reach 7-8 grades, and the weather resistance can reach 4-5 grades. Organic pigments with the same structure have slightly different light resistance and weather resistance due to different crystal forms, particle size distributions, surface coatings and use media.