Accelerated weathering degradation behaviour of polyester thermosetting powder coatings

The development of new products and their introduction in the market need rapid and reliable accelerated durability tests have the capacity to predict the service lifetimes of the materials. In this paper we report time-consuming standardised procedures in order to study the durability and the stability of typical polyester powder coatings, used as surface and structure white decorative finish in external architecture. SUNTEST, UVA and UVB accelerated aging tests were done in order to compare the resistance to weathering degradation of different kinds of coatings, four of standard durable and seven of superdurable type. The stability of the single formulation was determined through the evaluation of some chemicals and physical changes on aged samples respect the unaffected one. ATR measurements showed as the degradation differ mainly on the specific type of reactive binder system meanwhile the DSC measurements showed if the accelerate aging processes involved hydrolysis or an increase of the degree of polymerization. A good resistance, in term of gloss and colour retention, were also determined.