Ultraviolet Absorbers

Definition: These additives protect plastics against UV effects by preferentially absorbing the incident UV radiation and dissipating the associated energy in a harmless manner such as transformation into longer wavelength less energetic radiation. The use of absorbers is often required because exposure of many plastics to UV radiation, especially that in the near-violet region, can cause changes such as loss of gloss, crazing, chalking, discoloration, changes in electrical characteristics, embrittlement, and disintegration. The term is usually used to describe compounds which do not affect transparency to visible light. Such UV absorbers are a class of stabilizers which have intense absorption up to 350 to 370 nm, but are transparent in the visible. Also known as UV SCREENING AGENTS and ULTRAVIOLET STABILIZERS.