Research On Synthesis And Performance Of UV Cured Waterbornepolyurethane Acrylate Containing Sulfonic-carboxylic Groups

As legislation of volatile organic compounds(VOC) emission is becoming more and more strictly in recent years, solvent-based coatings are gradually substituted and new environmentally friendly coatings become the hot spot of research and development. UV-curing has the merit of efficient, energy saving and environmental. UV-curable waterborne polyurethane combines the advantages of UV curing and waterborne polyurethane, so it gives coatings more excellent properties.Waterborne polyurethane acrylate(WPUA) was synthesized with polyester sulfonate glycol, polyether glycol(DL2000), isophorone diisocyanate(IPDI), 2-hydroxyethyl methacrylate(HEMA), 2,2-dimethylol propionic acid(DMPA) being raw material in this thesis. The reaction conditions of preparation for the prepolymer were optimized. Firstly polyester/polyether glycol and IPDI reacted at 60~65℃ for 2hrs, then DMPA was added and the temperature was kept for 3hrs, at last HEMA was added and the temperature raised to 70℃ for 3hrs. And also, the structure of prepolymer was characterized by Infrared Spectroscopy(FTIR). Molar ratio of polyester/polyether glycol, Molar ratio of NCO/OH, DMPA content and the degree of neutralization on the performance of the WPUA dispersion were researched, such as appearance, average particle size and viscosity.The conditions of UV curing were studied and obtained conclusions as follows: photoinitiator 1173 was chosen as photoinitiator and optimal usage amount was 3%. The UV cured films were cured in 2min. The effects of molar ratio of polyester /polyether glycol, molar ratio of NCO/OH and photoinitiator usage amount on water resistance, acid and alkali resistance, thermal analysis, pencil hardness, tensile strength and elongation at break were researched. The properties of UV cured films were characterized through FTIR, thermogravimetry analysis(TGA), differential scanning calorimetry(DSC) and tension tester. The results were that water resistance, acid and alkali resistance were more affected by DMPA content when the sulfonic group content(0.8%) was constant. When the DMPA content was 3%, these properties of films were best. Molar ratio of NCO/OH, DMPA content and crosslinking density were the main influences of thermal analysis and mechanical property of the films. UV cured films were more thermostable, more flexible and had higher tensile strength, lower elongation at break and hardness in the case of less molar ratio of NCO/OH or DMPA content.