PAINTED THERMOPLASTIC OLEFIN SYSTEM - ASSESSING THE VARIABILITY OF ADHESION PROMOTER ADHESION PERFORMANCE FOLLOWING UV EXPOSURE

The development of test methods for assessing fundamental properties o f materials which influence in-service coating adhesion is important f or screening potential material candidates. The main focus of this stu dy was to develop a methodology for screening adhesion-promoting prime r materials used on thermoplastic olefin (TPO) systems as to their sus ceptibility to UV degradation. This work assesses the adhesion perform ance of a single unfortified (no UVA or HALS additives) 2K polyester-m ethane topcoat over a number of commercially available adhesion promot er systems following ambient UV exposure. Adhesion performance is corr elated with the relative photodegradation of the adhesion promoter mat erials. This study was specifically designed to simulate conditions of thin topcoat application and/or loss of light stabilizers in the pain t by adventitious processes that would render the adhesion promoter/to pcoat interface exposed to ambient UV radiation. Results of the adhesi on testing showed that there is a wide range in the performance of the adhesion promoters used in this study. Adhesion loss following ambien t exposure to UV radiation was observed in as little as 100 h to great er than 6300 h of exposure. The variation in the performance of the ad hesion promoters was found to correlate with the degree of photooxidat ion of the materials. These results suggest that this type of a method ology would be useful in assessing the relative sensitivity of polymer s used in adhesion promoter formulations when exposed to ambient weath ering conditions.