Photo-curable waterborne polyurethane acrylates with low VOCs and low odor by devolatilization and deodorizing

In order to remove VOCs in paints and coatings as more as possible, photo-curable waterborne polyurethane acrylates (WPUAs) were synthesized and an easy process to obtain low VOCs and low odor by the devolatilization technology was investigated. It was found that VOCs contents and WPUAs odors were significantly reduced by using the deionized water as the devolatilization aid chemical. With the conditions that the temperature was 75 °C, vacuum degree was 0.085 MPa, and the added deionized water content was 3 wt%, the VOCs content of WPUA was 33.6 mg/g with odor level 2 after devolatilization. Moreover, in the process of devolatilization, the increasing temperature strengthened the mass transfer process, thus the removal efficiency of VOCs was improved. Comparison with the WPUA coatings without devolatilization, the photo-cured films of deodorized WPUA coatings showed good thermal stability and excellent mechanical properties due to most of the solvents and small molecular impurities were removed. The WPUA coatings with low VOCs not only reduced environmental pollution, but also improved their coatings quality. At the same time, the devolatilization technology had the characteristics of simplicity and efficiency. Therefore, it was suitable for industrial production of organic photo-curable coatings in order to protect both environment and people's health as much as possible.