Preparation and Study on Properties of Castor Oil based Waterproof UV- curable Waterborne Polyurethane Coatings

Compared with solvent based coatings, the waterresistance of UV- curable waterborne polyurethane is poorer. To solve this problem, a kind of UV- curable waterborne polyurethane(UVWPU) whose backbone and end groups were both provided with unsaturated double bonds were prepared by controlling the ratio of n(OH(CO)) and n(NCO), and using castoroil(CO)and isophorone diisocyanate as the main materials. Particle size of UVWPU, waterresistance, thermostability, and mechanical properties of polyurethane films were studied. Experiment results showed that the particle size of UVWPU increased along with n(OH(CO))/n(NCO) increase. In addition, waterresistance, thermal stability and tensile strength of the films were all improved.The waterabsorption were 8% when n(OH(CO))/n(NCO) were 0.38. Meanwhile, the weightlessness temperature T5% could reach 280 ℃, the gel were 65%, and the tensile strength at break were 6.5 MPa. The gel ofcastoroil- based UVWPU films were lowerthan otherfilms, but theirwaterresistance were better.