The effectiveness of UV-LED photopolymerisation over conventional UV-mercury for polyurethane acrylate coating

• Main Authors: Ghazali, Siti Khairunisah, Syaiful Azim, Fatria Syaimima, Adrus, Nadia, Jamaluddin, Jamarosliza
• Format: Article
• Published: Tokai University 2019
• Subjects: TP Chemical technology
• Online Access: http://eprints.utm.my/id/eprint/87471/; http://dx.doi.org/10.2494/photopolymer.32.705
• Institution: Universiti Teknologi Malaysia

This paper presents the effect of UV-LED and UV-mercury as the light source toward curing behaviour of urethane acrylate coating. The UV-curable coating was prepared based on aliphatic urethane acrylate oligomer, 2-ethylhexyl acrylate (2-EHA), methyl methacrylate (MMA), trimethylolpropane triacrylate (TMPTA), and commercial photoinitiator. The effect of irradiation time on curing behaviour was investigated using Fourier Transform Infra-Red (FTIR) and the percentage of C=C conversion was calculated. From the ATR-FTIR spectra, the C=C absorption peak at 810 cm-1 and 1635 cm-1 was found to be decreased after UV irradiation, indicated the proceeding of the polymerisation reaction. In term of C=C conversion, UV-LED irradiation showed better results with 97-99% than UV-mercury irradiation which is 86-96%. It was also observed that the tackiness of the coating reduced via UV-LED irradiation, suggesting higher conversion of monomers. Gel fraction of the coating also measured and higher gel fraction values, > 98% in this study was associated with higher cross-linking density. The results of this study depicted that UV-LED is a viable alternative to replace UV-mercury-based lamp in the coating industry.