Lightfastness of Paperboards Coated with UV-Cured Varnish

UV cured varnish is gaining wider acceptance in packaging, as it offers very high gloss and excellent scratch resistance to the surface. Such packages are displayed in retail environments with varying lighting conditions. And it is important to understand the lightfastness of such materials. Two different commercially available UV varnishes have been coated on paperboards manufactured with & without fluorescent whitening agent (FWA). Accelerated lightfastness tests were conducted on those samples and results are interpreted in terms change in CIELAB color coordinates and the shifts in reflectance spectrum. The UV varnished paperboard samples demonstrated a significant yellowing, independently of the presence of fluorescent whitening agents in the paperboard.