The invention relates to a preparation method of high
solid content waterborne
polyurethane. The waterborne
polyurethane is higher than common
organic solvent in
latent heat of
evaporation, and water
solvent type
polyurethane in waterborne polyurethane of the same
solid content is slow in
solvent evaporation and needs long
drying time. The preparation method comprises the steps of mixing
polymer polyol with polyisocyanates under the protection of
nitrogen, stirring evenly and then adding catalyst for reacting; adding a hydrophilic chain
extender for reacting; cooling, adding a
solvent and a neutralizer so as to obtain a
prepolymer and stirring at high speed so as to disperse in deionized water; adding the chain
extender, stirring, reducing pressure and removing the solvent through
steaming so as to obtain the waterborne polyurethane
emulsion; and preparing the
prepolymer of different size distribution, dispersing in the waterborne polyurethane
emulsion along with velocity mixing, and stirring for 1-4 hours. The waterborne polyurethane
emulsion has wide size distribution and low
viscosity, is stable, and can solve the key technical problems of high latent of
evaporation, slow volatilization, long
drying time, low production efficiency and the like in the field of research of the waterborne polyurethane.