Studies on the interaction of photoreactive light stabilizers and UV-absorbers

Coatings, like all organic substances, are submitted to photoageing during their life time. Ultraviolet light absorbing additives (UVAs) and hindered amine light stabilizers (HALS) often are added to improve their performance. These additives can be lost by migration to the surface, where they are exposed to physical depletion, as well as through photodegradation of the molecule itself. Modifying hindered amine light stabilizers by introducing a photoreactive site gives the possibility to fix the stabilizing molecule onto the polymer matrix. The influence of the presence and the type of UV absorbers onto the photografting reaction will be discussed.