UV absorbers function by competitive absorption of damaging UV radiation. These additives generally absorb UV radiation much more strongly than the polymers that they protect. The excited states formed upon UV absorption relax to the ground state extremely rapidly and efficiently through radiation-less processes, which imparts high stabilization efficiency and excellent photostability.
UV absorbers are categorized by chemical class, for example benzotriazoles, benzophenones, and triazines. Each class has its own UV absorbance characteristics. For example, benzophenone- and triazine-types tend to absorb more strongly in the short wavelength UV-B region than the benzotriazole-types.
These products can be effective when used alone for the light stabilization of PVC and some engineering plastics such as polycarbonate. UV absorbers are also used in plastic packaging applications to protect sensitive package content from the damaging effects of UV radiation. Combinations of UV absorbers and HALS often show synergistic performance and represent the state of the art for light stabilization in styrenic polymers, coatings, and other plastics.
Amfine offers a full range of UV absorbers, including benzotriazole- (LA-29, LA-31RG, LA-32, LA-36), benzophenone- (1413), and triazine-types (LA-46). FDA cleared products are also available for packaging applications.