AbstractThe photostability of a coil‐coating composite consisting of layers of plasticized PVC and a methylmethacrylate/ethylacrylate/acrylic acid copolymer as well as of several model systems was investigated. Changes of the UV irradiated samples were characterized by UV‐vis spectroscopy, the determination of the remaining thermal stability of PVC, and checking the adhesion strength. Photooxidation may cause failure of the coating especially by degradation in the interface layer of the primer to the metal.