Coatings are subject to photoaging during their lifetime. Ultraviolet radiations absorbing additives (UVAs) and hindered amine light stabilisers (HALS) often are added to improve their performance. To improve performance of coatings, it is important to use optimum quantity of such additives.
In this study, hydroxyl‐terminated polyester was synthesised and then crosslinked using isophoronediisocyanate. These clear coats were then stabilised with various additives such as Tinuvin 1130, 123 and 292. The synergistic effect of these additives was also studied. The optical properties of coatings such as yellowness, whiteness and gloss of coatings were studied after exposing these coatings to various environments such as QUV weathering, direct UV and xenon arc.
The results showed that the coatings stabilised with combination of additives performed better than the unstabilised coatings as well as single additive coatings. A synergism was observed when using a combination of the UVAs and HALS.
The additives used were found to be compatible with the binder systems under study and was not found to be universally compatible with all resins.
UV degradation is a major concern in coatings both aesthetically and functionally. This study aimed at optimising the concentrations of UV stabilisers in order to increase the effective life time of exterior coatings.
UV stabilisers are routinely used in coatings for exterior applications. However, our aim was to optimise the concentrations of these additives in the coating so as to reduce the cost while keeping the performance of the coatings unaffected. By studying the synergy of the additives, we have also optimised their concentrations to further increase the life of the coatings.
