Paint Weathering Research at Ford

摘要

The object of an accelerated weathering test for automotive paint systems is to provide information on long-term performance well in advance of the results from actual outdoor exposure tests. The use of a trustworthy accelerated weathering test could reduce the lead time for the introduction of new paint systems with lower solvent emissions, with improved acid etch, chip, scratch, and mar performance, and with appearance changes designed to attract new customers. Unfortunately, after more than 50 years of research, a trustworthy accelerated weathering test suitable for all coating chemistries does not yet exist.Specialized tests that can reproduce the in-service weathering performance of specific coating chemistries do exist. Such tests are the end result of combining years of outdoor exposure test results with years of accelerated weathering test results to produce correlations. Once correlations have been established for a given coating chemistry, the test becomes a powerful development tool for that chemistry; however, there is no reason to expect that an accelerated weathering test tailored to fit a specific coating chemistry should necessarily be appropriate for other coating chemistries. In fact, treating specialized weathering tests as if they were generic has lead to costly mistakes. Thus, coating suppliers and their customers are very hesitant to introduce new coating chemistries or even seemingly minor formulation changes on the basis of accelerated weathering test results alone. Most prefer to wait for the results of at least 5 years of outdoor exposure tests from several environmentally different locations before making decisions. Waiting for the results of outdoor exposure tests slows the introduction of new paint technology dramatically. It, therefore, comes as no surprise that research designed to produce a trustworthy accelerated weathering test for automotive coatings remains very active. Several consortia, as well as numerous private industry research groups including a group at Ford Motor Co., are presently addressing this topic.