Determination of ultraviolet light absorber longevity and distribution in automotive paint systems using ultraviolet micro-spectroscopy

摘要

Ultraviolet light absorber additives (UVAs) are added to the basecoat and clearcoat layers of modern, multi-layer, automotive paint systems in order to protect the clearcoat and screen the underlying layers from harmful UV light. Unfortunately, these UVAs are subject to photodegradation resulting in diminished UV protection as a paint system weathers. This paper describes an ultra- violet micro-spectroscopic technique that has been developed to measure ultraviolet light absorber content, location, and longevity in the clearcoat layer of complete, intact, automotive, paint systems. Three automotive paint systems containing different UVAs were examined initially and after exposure in Florida. UVA content and distribution were determined in each of the paint systems with weathering and the longevity was determined. This work demonstrates an accurate, unambiguous technique for quantifying UVA loss in coatings.