Preparation method of super-hydrophilic polyurethane used as long-acting antifogging agent

The invention provides a preparation method of super-hydrophilic polyurethane used as a long-acting antifogging agent, comprising the following steps: adding acrylic acid grafted modified polyester polyol into a reaction kettle; dehydrating at 100 DEG C to 150 DEG C in vacuum for 1h to 4h; after cooling to a room temperature, adding hexamethylene diisocyanate and adding acetone for dissolving; raising the temperature to 80 DEG C to 90 DEG C and dropwise adding a catalyst; reacting for 1.5h to 3h to obtain a pre-polymer; adding 2-hydroxy-3-(2-allyloxy)-1-sodium propylsulfonate salt into the pre-polymer and continually reacting for 0.5h; then adding silicon-containing diol and dihydromethyl propionic acid; raising the temperature to 60 DEG C to 75 DEG C and carrying out a chain extension reaction for 1h to 1.5h; after cooling to the room temperature, adding triethylamine under high-speed stirring and stirring for 5min to 10min; adding water for emulsifying to obtain the super-hydrophilic polyurethane. When bein