Developing a Novel Phosphorus–Nitrogen Flame Retardant from Rapeseed Meal and Its Application on Cotton Fabric

In this study, according to the design principle of intumescent flame retardant, rapeseed meal was modified into a phosphorus-nitrogen flame-retardant HPRm by using H 2 O 2 –H 3 PO 4 system, and L9(3 4 ) orthogonal experiment was designed to optimize the modification conditions. Cotton fabric was durably flame-retarded with HPRm via an optimized pad-dry-cure process. With only a 12.74% weight gain, the treated fabric achieved an LOI of 39.4% and a 34 mm damage length in the VFT. In CCT, the PHRR and THR of HPRm cotton decreased significantly. In addition, since HPRm can form multiple covalent bonds with cotton fibers, the LOI of HPRm cotton remained at 35.7% after 50 washing cycles and self-extinguished in VFT. At the same time, the results of TG, TG-IR and char residue analysis confirmed that HPRm changed the pyrolysis pathway of cotton fabric, reduced the production of combustible gas and formed a stable P/N char layer on the surface of cotton fiber, which effectively interrupted the combustion of cotton fabric. HPRm finishing somewhat reduced the fabric’s mechanical properties and softness. This work provides a feasible method for realizing the resource utilization of traditional agricultural by-products and the environmentally friendly and durable flame retardant of cotton fabrics.