Patent ID: 7193011

Claim:
A method of preparing water-dispersible poly (urethane-urea) having aliphatic-aromatic isocyanate comprising the steps of: reacting polyester polyol comprising at least 30 wt % of crystalline polyol having a melting point of higher than 30° C. and dimethylol propionic acid (DMPA) at 50 to 60° C. at 90 to 120 rpm/min, and further reacting for 20 to 40 minutes after adding an aromatic isocyanate compound to prepare a hydroxyl (OH)-terminated prepolymer; heating said the OH-terminated prepolymer to 70 to 80° C. and adding excess aliphatic isocyanate compound to prepare an isocyanate (NCO)-terminated prepolymer; cooling said NCO-terminated prepolymer to 50 to 70° C. and neutralizing it for 20 to 30 minutes by adding tertiary amine; and water-dispersing said neutralized NCO-terminated prepolymer by adding water while stirring at a rate of 600 to 1000 rpm/mm and chain extending it for 2 to 4 hours by adding a chain extender.