Fabrication of Flame-Retardant and Anti-dripping Waterborne Polyurethane Containing Phosphorus/Silicon via a Green and Feasible Strategy

Waterborne polyurethane (WPU), a green polymer material, has been widely applied in various fields. Unfortunately, the development of WPU is severely restricted by its flammability and melt flow. A flame-retardant and anti-dripping PAS-WPU emulsion has been manufactured by introducing flame-retardant modified WPU and phytic acid-APTES solution (PAS). Benefiting from the complex cross-linked network formed among phytic acid, APTES, and WPU, the flame-retardant and anti-dropping performance of the PAS-WPU film is significantly improved, and its strength is increased from 6.5 to 9.2 MPa. Due to a high limiting oxygen index of 34.1%, the PAS-WPU film cannot be ignited in the vertical combustion test and the formation of melt droplets is not observed. The cone calorimetry test demonstrates that the peak heat release rate, total heat release, and total smoke production for combustion of the PAS-WPU film are decreased by 48, 30, and 30%, respectively, compared to the behavior of WPU. In addition, the PAS-WPU emulsion can be applied as a flame-retardant finishing for polyester fabrics. The flame retardancy and mechanical properties of the treated polyester fabrics are dramatically better than those of untreated fabrics. A feasible and green solution for manufacturing flame-retardant and antidripping waterborne polyurethane has been demonstrated.