Curing behaviour of uv-led curable urethane acrylate coating

Abstract

Recently, UV radiation coating has been tremendously utilized in coating as it demonstrated fast curing and solvent free formulation. In this study, UV-LED technology was employed as a new alternative to conventional UV coating with safer environment and better perfomance. The UV curable coating was prepared based on aliphatic urethane acrylate oligomer, 2-ethylhexyl acrylate (2-EHA), methyl methacrylate (MMA), trimethylopropane triacrylate (TMPTA) and hydroxyphenyl ketone photoinitiator (Chivacure 300). The effect of UV-LED irradiation time on curing behaviour was investigated using Attenuated Total Reflectance- Fourier Transform Infra-Red (ATR-FTIR) and gel fraction determination. In addition, the C=C absorption peat at 1635 cm-1 was found to be decreased after UV curing. The degree of conversion (DC) was also calculated from the FTIR spectra and it was found that the DC increased with the increasing of UV irradiation time. Gel fraction of the cured coating was sharply increased after exposed to UV-LED irradiation. However, the gel fraction did not achieve 100% due to the entrapment of monomer in polymer network. In brief, UV-LED will steer the key interest of this research in order to pursue green aspects in phopolymerization technology.