Dapawan Kunwong, Natthawadee Sumanochitraporn and Supranee Kaewpirom

pp. 201 - 207

Abstract

A hybrid organic-organic urethane acrylate oligomer was synthesized by the reaction of polypropyleneglycol (PPG),
2,4-toluene diisocyanate (TDI) and 2-hydroxyethyl methacrylate (HEMA) using dibutyltin dilaurate (DBTDL) as a catalyst.
The urethane acrylate oligomer’s structure was characterized by nuclear magnetic resonance (NMR) and Fourier transform
infrared spectroscopy (FT-IR). Two UV-curable coatings were prepared by blending the urethane acrylate oligomer, a reactive
monomer (1,6- hexanediol diacrylate (HDDA) or trimethylol propane triacrylate (TMPTA)) and a photoinitiator (2,2-dimethoxy-2-phenyl acetophenone). The UV curing process of such coatings was monitored by FT-IR and determination of the
gel fraction. It was found that as the UV dose increased, the specific peaks at 1635 cm^-1 and 810 cm^-1, related to the carboncarbon double (C=C) bond, decreased. Gel fraction of the cured coating film was found to increase with increasing radiation
time. Thermal properties of the cured coating were also investigated using differential scanning calorimetry (DSC) and
thermal gravimetric analysis (TGA).

Keywords

• UV-curable coating
• urethane acrylate oligomer
• gel fraction
• reactivemonomer
• thermal properties