Water-borne hyperbranched structure modified polyurethane polymer and preparation method thereof, and self-repair diffuse reflection coating composition

The invention discloses a water-borne hyperbranched structure modified polyurethane polymer and a preparation method thereof, and a self-repair diffuse reflection coating composition. The preparationof the polymer comprises the following steps: performing reduced pressure vacuumization on aliphatic polyether diol and aliphatic polyester glycol at a temperature of 90-150 DEG C, cooling to 60-90 DEG C, and adding a catalyst and aliphatic diisocyanate; adding a hydrophilic chain extender for reacting for 1-3 hours; adding a hydroxy-terminated hyperbranched polymer, and reacting for 1-2 hours; adding a hydrophilic chain extender, and reacting for 1-2 hours; cooling to a normal temperature, and adding a neutralizer to regulate the pH value to 7-9; adding a sulfonate hydrophilic chain extenderand deionized water for reacting for 0.5-1 hour, thereby obtaining the water-borne hyperbranched structure modified polyurethane polymer. The self-repair diffuse reflection coating composition disclosed by the invention compri