On the Combined Use of UVA, HALS, Photooxidation, And Fracture Energy Measurements to Anticipate The Long-Term Weathering Performance of Clearcoat/Basecoat Automotive Paint Systems

By J.L. Gerlock, A.V. Kucherov, M.E. Nichols

Transmission UV spectroscopy measurements of clearcoat ultraviolet light absorber (UVA) disposition, electron spin resonance (ESR) spectroscopy measurements of clearcoat and basecoat Active hindered amine light stabilizer (HALS) disposition, and transmission Fourier transform infrared (FTIR) measurements of photooxidation have been carried out on 5 µm thick slices of clearcoat/basecoat/primer/e-coat paint systems on steel panels as a function of outdoor exposure.

These analysis results are combined with clearcoat fracture energy measurements to assess the possibility that a clearcoat/basecoat paint system will resist catastrophic cracking/peeling failure at long times. Taken together, all results indicate that these nontraditional paint weathering performance metrics should be added to the existing repertoire of paint weathering performance metrics to ensure that inferior clearcoat/basecoat automotive paint systems are not introduced into service.