Synthesis and Characterization of Aliphatic Tri-functional Oligomeric Urethane Methacrylate used for UV-Curable Aluminum Pigmented Coatings

Abstract

A new UV-curable coating with aluminum pigments was developed as part of an effort to replace chromium coatings, which raise health and environmental concerns. For achieving this, aliphatic tri-functional oligomeric urethane methacrylate (ATOUA) was synthesized using trimethylol propane (TMP), isophorone diisocyanate (IPDI), hydroxyethyl methacrylate (HEMA) and dibutyltin dilaurate (DBTDL) as a catalyst. In order to obtain a metallic shine effect, leafing and non-leafing aluminum pigments were formulated with ATOUA to obtain a series of coatings. The UV-curable aluminum pigmented coatings were prepared by blending ATOUA, 1,6-hexanediol diacrylate (HDDA) and trimethylol propane triacrylate (TMPTA) as reactive diluents, benzophenone as photoinitiator, N-methyl diethanolamine as co-initiator, aluminum pigments, and wetting and dispersing agent (OA 10EO). Surface morphology of the coatings was investigated through SEM. FTIR; 1H-NMR and 13C-NMR spectroscopes were used to characterize composition of the synthesized oligomer. Physical, chemical and mechanical properties of surface coatings have been determined using König hardness, cross cut, impact, gloss, mandrel, cupping and salt spray test. Thermal properties of the cured coating were also investigated by means of DSC and TGA.