Synthesis and Characterization of Halogen-Free Flame Retardant Two-Component Waterborne Polyurethane by Different Modification

Diethyl <i>N</i>,<i>N</i>-bis­(2-hydroxyethyl)­aminomethyl­phosphonate and halogen-free poly­(phosphate) as reactive halogen-free flame retardants and soft or hard segment modifiers were compounded to waterborne polyurethane polyols after being emulsified and then were mixed with isophorone diisocyanate and dimethylol­propionic acid to synthesize two-component waterborne polyurethanes having fire resistance. As a result, the rheological behavior of prepolymer emulsion really accords with characteristics of non-Newtonian fluid. The highest limit oxygen index is 27.8% in two-component system modified by hard segment, which was 527.5% than the clean; meanwhile, one is 28.6% in another two-component system, which was 627.6% than the clean. The hardness, solvent resistance, and mechanical property in both of the two-component systems are outstanding. Adding flame retardant can effectively improve the flame resistance, tensile strength, and pot-life of two-component waterborne polyurethanes, especially in being modified by soft segment