Effects of Small Molecular Weight Silicon-Containing Acrylate on Kinetics, Morphologies, and Properties of Free-Radical/Cationic Hybrid UV-Cured Coatings

摘要

A series of UV-curable, silicon-containing mixtures were prepared by adding different micro amounts of small molecular weight silicon-containing acrylate KH570 to an interpenetrating polymer network system composed of cycloaliphatic polyurethane acrylate, trimethylolpropane triacrylate, cycloaliphatic epoxy resin, free-radical photoinitiator Irgacure 754 and cationic photoinitiator Irgacure 250 with a weight ratio of 15 : 15 : 65 : 1 : 4. Hybrid coatings with different addition amounts of KH570 (0.2, 0.6, 1.0 wt %) were cured from the mixtures by UV-initiated free-radical/cationic dual curing technique. Final reactant conversions and photopolymerization rates of the hybrid UV-cured coatings were improved with the increase of KH570 content, as evaluated by conversion profiles. The morphologies and microstructures were characterized by scanning electron micro-scopic, atomic force micrographic, and fourier transform infrared spectrophotometer measurements. Thermal, mechanical, and surface properties of the hybrid UV-cured coatings were investigated. The increase in KH570 content caused a decrease in mechanical properties besides the breaking elongation. Thermo-gravimetric analysis revealed that the incorporation of silicon into cross-linked network structure resulted in high thermal stability. The surface properties of hybrid UV-cured coatings, such as hardness, contact angle, flexibility, and glossiness were also examined. It is found that transparent hybrid coating with the addition of 1.0 wt % KH570 exhibited a relatively higher contact angle as a direct result of a relatively higher hydrophobic surface. These researches showed that micro amounts of small molecular weight silicon-containing acrylate could greatly influence the morphologies of liquid nitrogen quenching cross sections and properties of hybrid UV-cured coatings and could be used to modify UV-cured coatings for some superior properties.