Preparation and Properties of Flame Retardant Waterborne Polyurethane Emulsion
A series of modified waterborne polyurethane emulsions(ZWPU)were prepared with phthalic anhydride polyester diol(PH-56),neopentyl adipate(PNA),isophorone diisocyanate(IPDI)and dimethylolpropionic acid(DMPA)as basic raw materials,and trimethylolphosphate oxide(THPO)as crosslinking agent.The structure of the films was characterized by Fourier transform infrared spectroscopy(FTIR).The properties of the films were analyzed by mechanical properties and flame retardant test.The results show that with the increase of THPO contents,the hardness of film pencil decreases,the limiting oxygen index and vertical combustion increase first and then decrease,the thermal stability increases and the water resistance decreases.When the THPO content is 0.77%(the mass ratio to polyurethane prepolymer),the hardness of the film pencil is 3H,the adhesion is 0,the limiting oxygen index is 24%,the vertical combustion is V-1,the heat release rate is reduced by13.86%,the tensile strength is49.98 MPa,and the elongation at break is 461.41%.