UV-curable organic-inorganic hybrid hard coatings for metal sheets

摘要

A new type of UV-curable organic-inorganic hybrid oligomer was synthesized from vinyltrimethoxysilane (VTMS), tetraethylorthosilicate, and colloidal silica (CS) using a sol-gel method. UV-curable hybrid hard coating formulations were then prepared by mixing the organic-inorganic hybrid oligomer and acrylic monomers, trimethylolpropane triacrylate and tetrahydrofurfuryl acrylate, with a levelling agent and a photoinitiator. The oligomer was hydrolyzed and condensed from alkoxysilane and CS to obtain the UV-cured hybrid films. The hybrid oligomer and resulting hybrid films were characterized by Fourier transform infrared spectroscopy, Si-29 nuclear magnetic resonance spectroscopy, scanning electron microscopy, and ultraviolet-visible spectrophotometry to confirm the chemical functionality, oxo-silicon signal, cross-sectional morphology, and transparency, respectively. When the concentration of the CS/VTMS mixture in the organic-inorganic hybrid oligomer was 0.50 mol, remarkable pencil hardness (up to 5H) with excellent transparency was observed. The hardness and transparency of the UV-cured hybrid coating films were improved significantly by increasing the CS content in the organic-inorganic hybrid oligomer.