Defination
UV absorber is a light stabilizer, can absorb sunlight and fluorescent light source in the ultraviolet part, and itself does not change. It can protect the plastic from the photo-oxidative degradation caused by the ultraviolet ray irradiation, thus prolongs the service life of the products greatly. Under the sunlight or fluorescence, plastics and other polymer materials are oxidized automatically due to the effect of ultraviolet light that lead to deterioration of polymer substance thereby damage the appearance and mechanical functions respectively. The ultraviolet absorber can selectively absorb this high-energy ultraviolet light, making it harmless energy release or consumption. Depending on the type of the polymer, the wavelength of ultraviolet radiation is not the same. Different ultraviolet absorbers absorb ultraviolet light of different wavelengths. When we use it, UV absorbers should be selected according to the types of polymer.
Requirements to be UV absorbers
1. strongly absorbing ultraviolet light (especially the wavelength of 290-400nm);
2.good thermal stability, even in the processing will not change due to heat, thermal volatile small;
3. good chemical stability, no adverse reaction with the material components in the product;
4.good compatibility, can be evenly dispersed in the material, do not spray frost, not ooze;
5.absorbent itself has good photochemical stability, does not decompose or change color;
6.colorless, non-toxic, and odorless;
7.resistant to immersion;
8.cheap, easy to get.
UV absorbers by chemical structure can be divided into the following categories: salicylic acid esters, benzophenones, benzotriazoles, substituted acrylonitrile, triazine and other categories. UV absorbers can be used for plastics, coatings, dyes, automotive windshields, cosmetics, pharmaceuticals, sunscreen and so on.
Common UV absorbers
Phenyl ester of salicylate(Component: phenyl o-hydroxybenzoate);
UV-absorber UV-P(Component: o-nitroaniline, p-cresol reaction products);
UV-absorbing agent UV-O(Component: 2,4-dihydroxybenzophenone);
Ultraviolet absorber UV-9(Component: 2-hydroxy-4-methoxybenzophenone);
UV-absorbing agent UV-531(Component: 2-hydroxy-4-n-octoxybenzophenone);
UV absorber UVP-327(Component: 2-(2'-hydroxy-3 ', 5'-di-tert-phenyl)-5-chlorobenzotriazole);
UV absorbers(Component: resorcinol monobenzoate);
Light stabilizer AM-101(Composition: 2,2'-thiobis (4-t-octylphenoxy) nickel);
Light stabilizer GW-540(Component: tris (1,2,2,6,6-pentamethylpiperidyl) phosphite);
Light stabilizer 744(Component: 4-benzoyloxy-2,2,6,6-tetramethylpiperidine);
Light stabilizer HPT (Ingredients: hexamethylphosphoric triamide).
Appilication
It is used in plastics, chemical fiber, paints and petroleum products, especially for light-colored transparent products; used in paint and various plastic products. It is especially effective for PVC, polyester, acrylic, resin, polystyrene and light-colored transparent furniture. It is also a good cosmetic additive. The amount is 0.1-0.5%; used as Cu (II) gravimetric determination reagent. Benzophenone UV absorbers are excellent stabilizer for polyethylene and other synthetic plastics, the amount is about 0.5 to 1.5%, and it can also be used for paint, pigment, paint industry, fine white wax and daily cosmetics.
