Preparation of high-solid, low-viscosity waterborne polyurethane: based on multiparticle size composite emulsification

In this paper, waterborne polyurethane (WPU-SL) with high solid content and low viscosity was successfully prepared by compounding large particle size emulsion (WPU-L) with a variety of small particle size emulsions (WPU-S) by investigating the effects of small particle size type, particle size ratio, and volume ratio on the emulsion properties. A series of characterization techniques of the waterborne polyurethane was carried out by FTIR, DSC, contact angle, viscometer, particle size meter, and universal testing machine. The results show that the WPU-L/WPU-S = 5/1 emulsion has a high solid content, good emulsion stability, and excellent coating film properties. When WPU-S 1 and WPU-S 3 , two small particle size emulsions with a particle size ratio of 2.45 and 3.79, were emulsified with WPU-L, the solid content was up to 61.23%, the viscosity was only 342 mPa s, the tensile strength reached 20.97 MPa, and the adhesion grade was 5B, which was the most excellent overall performance, showing satisfactory results. Graphical