Preparation method of water-based polyurethane for grinding Y-type branched zero-VOC (Volatile Organic Compounds) special color paste

The invention discloses a preparation method of Y-type branched zero-VOC (volatile organic compound) waterborne polyurethane for special color paste grinding, and particularly relates to the technical field of macromolecules, the waterborne polyurethane has a Y-type structure, the Y-type structure is obtained from trihydric alcohol or amine containing reactive hydrogen, the waterborne polyurethane comprises a hydrophilic polyhydric alcohol chain segment and a hydrophobic polyhydric alcohol chain segment, and the hydrophilic polyhydric alcohol chain segment and the hydrophobic polyhydric alcohol chain segment are in a Y-type structure. The end group in the structure is polyhydric alcohol and polyamine containing reactive hydrogen for low-temperature end sealing, a low-temperature end sealing technology is adopted, side reaction is avoided, intermolecular crosslinking is avoided, meanwhile, energy consumption is reduced, reaction time is shortened, in the three-branched molecular structure, a star chain is prov