The preparation of high solid content waterborne polyurethane by special physical blending

On the basis of small-particle waterborne polyurethane(WPU-S) and large-particle waterborne polyurethane(WPU-L) which were both narrow in particle size distribution, high solid content waterborne polyurethane(WPU-H) with particle bimodal distribution was prepared by the special physical blending method. Three kinds of waterborne polyurethane were characterized by FTIR, DSC and TEM and the particle size, viscosity and solid content of the emulsion samples were measured and compared. The result showed that the WPU-H contained two kinds of particles from WPU-L and WPU-S and showed a higher solid content than WPU-L or WPU-S. Different combinations led to different high solid content, especially WPU-H-4 reached a high solid content of 66.07% and a low viscosity of 285 mPa.s by mixing WPU-L-1 and WPU-S-4.