Development of lignin-based waterborne polyurethane materials for flame retardant leather application

A series of lignin-based biological waterborne polyurethanes (LBWPU) with excellent properties were synthesized by prepolymerization with different contents of sodium lignosulfonate aqueous solution (NaLS) as dispersant. Biological isocyanate (1, 5-pentamethylene diisocyanate), biological polyether polyol (H-2000) and castor oil were used as the main reaction materials to prepare waterborne polyurethane with biological content up to 70%, which had excellent storage stability. The effects of different contents of NaLS on the thermo-mechanical properties, mechanical properties and thermal stability of polyurethane films were studied. With the increase in NaLS content, the mechanical properties, storage modulus and water resistance of LBWPU films were significantly enhanced. Meanwhile, the limiting oxygen index of the prepared LBWPU could reach 24.7% after blending with the flame retardant, showing good flame retardancy. In this work, the water-based polyurethane materials with high bio-base content could be used as a film-forming agent in the field of leather finishing agent, which has an important influence on improving the flame retardant of leather. Graphical abstract