Waterborne polyurethane coating material suitable for winter and preparation method thereof

The invention discloses a water-based polyurethane coating material suitable for winter. The water-based polyurethane coating material comprises the following raw material components in percentage by mass: a water-based hydroxy acrylic resin, a polyaspartic acid ester resin, water, a water-oil universal dispersant, a defoaming agent, white carbon black, a pigment, barium sulfate, a pH regulator, a rheological aid, an emulsifier, an accelerant, an ultraviolet absorber, a cosolvent, an HDI curing agent, and PMA. The method comprises the following steps: 1) pressurizing and heating a polyaspartic acid ester resin; (2 adding a water-based hydroxy acrylic resin, water, a water-oil universal dispersant and a defoaming agent into a tank, and stirring; 3), adding an accelerator into the tank; 4) adding a pigment, barium sulfate and white carbon black;5) adding slurry into a grinding machine; 6) adding a polyaspartic acid ester resin into the slurry; and 7) sequentially adding a pH regulator, a cosolvent, an ultraviol