Preparation of UV curable polyurethane-acrylate emulsion and its strengthening effect for paper

Waterborne UV curable polyurethane-acrylate emulsion was prepared with isophorone diisocyanate (IPDI), polycaprolactone diols (PCL1000), 2, 2-dimethylolbuty ricacid (DMBA), pentaerythritol triacrylate (PETA) and acetone as raw materials. And the emulsions were utilized for paper surface sizing. Fourier transform infrared spectrometer (FT-IR) and light scattering were used to analyze the structure of emulsion; effects of n (NCO)/n (OH) (R value) on the emulsion properties were systematically studied, as well as the water resistance and mechanical property of corresponding films. In addition, effects of UV curing on paper physical properties were discussed. The results showed that the emulsions were stable and the films displayed good water resistance and mechanical property, the water absorption decreased to 3.66% when n (NCO)/n (OH) =1.6, m (PETA) =12.6%. After UV curing, the wet strength of paper increased to 41.65%, and the ring crush index of paper reached 5.25 N &middot m/g.