Waterborne And Dual Curable UV Coatings With High Solid Content

UV curing technology has been an efficient and energy saving technology, whichhas been developed since the nineteen sixties. It has lots of preferred advantages such as a lowVOC emissions, protection of volatile solvent, fast curing speed, energy saving, goodcomprehensive performance of the cured film and so on. Dual curing technology is a mixedcuring technology, which combines the UV curing technology and other kinds of curingtechnology. Since the UV curing itself has varieties of disadvantages. The UV cured materialsconfine to the capacity of UV transmission. It applies only in the compound materials whichconsist of transparent reinforced material and transparent resin. It is difficult for applicationsin the color system. It subjects to the shape of objects for the shade part can’t be cured. Dualcuring method combines various polymerization advantages and shows good synergisticeffect. Dual curing is an innovation method for the modification of polymer materials.The UV curable waterborne polyurethane dispersions (PUD) with50%solid contentwere synthesized with isophorone diisocyanate (IPDI), polyester diols (PBA) as the main rawmaterials, which were modified with epoxy resin. The reaction of hydroxypropyl acrylate(HPA) and pentaerythritoltriacrylate (PETA) on the polyurethane macromolecules of theoligomers let their PUD have carbon-carbon double bonds and make them to bephotosensitive. The tensile strength, hardness, size and other performance of UV curingwaterborne polyurethane films were investigated. Meanwhile, the dynamic mechanicalanalysis (DMA) and cross section structure characterization with SEM of the coating filmswere tested. The results showed that the tensile strength and hardness of UV coating increasedwhen the double bond content increased. DMA tests showed that when the content of doublebond decreased, the soft segment Tg (s) transferred to low temperatures and the hard segmentTg (h) transferred to the high-temperature. Thus, the phase separation tended to be completed.SEM tests showed that when the degree of cross-linked resin increased, the degree ofresistance to fracture increased.In addition, the epoxy acrylate resins could be both UV-cured and heat-cured, whichwere prepared with epoxy resin and acrylic acid. Because the initiator and accelerator wereadded into the resin, the resin could be cured fast under the ultraviolet light radiation andcould be cured during one hour under the heating condition when the temperature is100centigrade. The influencing factors of UV-curing films, heat-curing films and the propertiesof the cured film were studied and tested. The structure of the product was characterized by FTIR. The heat resistance of the cured film was analyzed by DSC–TG. The results showedgood properties and good heat resistance either in the condition of UV-curing or heat-curing。...