Scientists in Korea synthesized tetrafunctional urethane acrylates based on different types of diisocyanates and then prepared a series of five UV-cured hard coatings on polycarbonate (PC) substrate. The coating syrups consisted of the urethane acrylate with reactive hardening acrylic monomer (PETA; pentaerythritol tetraacrylate) and reactive diluent (hydroxyethyl acrylate). The tribological properties and transparency of the UV-cured hard coatings were investigated.
When the content of PETA was increased in all of the UV-cured hard coating series, better tribological properties were obtained. The surface hardness order of the UV-cured hard coating series was toluene diisocyanate (TDI) > toluene diisocyanate (IPDI) > 4,4′-methylenebis(phenyl isocyanate) (MDI) > 4,4′-methylenebis(cyclohexyl isocyanate) (HMDI) > 4,4′-methylenebis(cyclohexyl isocyanate) (HDI). All UV-cured hard coatings had a transmittance of over 89% in the visible wavelength range.
This article is published on Polymer Bulletin, pp 1–13.