UV-curing of titanium dioxide pigmented epoxy acrylate coating on ceramic tiles

An experiment on surface coating of ceramic tiles with titanium dioxide (TiO2) pigmented acrylate formulations have been done using UV-curing system. A coating formulation is the mixture of epoxy acrylate resin (80 mass% aromatic epoxy acrylate in 20 mass% hexandiol diacrylate), tripropylene glycol diacrylate (TPGDA) monomer, titanium dioxide pigment and photoinitiator of 2,2-dimethyl-2-hydroxy acetophenone (Darocur 1173). Coating on ceramics was carried out with a wire bar coater to get film thickness of around 150 μm. UV-curing was conducted by using 80 Watt/cm intensity UV-source at a fixed photoinitiator concentration and exposure time (represented by conveyor speed). Concentrations of titanium dioxide and TPGDA in the coating formulation were varied to evaluate their effect on physical, mechanical and chemical properties of cured films. A fixed photoinitiator concentration and conveyor speed used in the experiment were determined after evaluating the pendulum hardness of cured films in a sequence of experiments. Parameters observed were viscosity, contact angle, pendulum hardness, gloss, adhesion, color value, and chemical, solvent and stain resistance.