Preparation of Flame-Retardant Wool/Nylon Fabrics With Superior Washing Durability by Covalently Grafting of Bio-Resourced Pyridoxal Phosphate

Flame-retardant fabrics require both washing durability and skin affinity. However, their development faces significant challenges due to the weak interaction between flame retardants and fabrics, and the generally high mass loading needed to achieve effective flame retardancy. Herein, we developed halogen- and formaldehyde-free flame-retardant wool/nylon (W/N) fabric through covalent grafting of bio-resourced pyridoxal phosphate (PP). The grafting achieved a very low weight gain of 3.3%, yet the resulting W/N-PP fabric exhibited a high limiting oxygen index (LOI) of 31.3%, corresponding to an 18.1% increase over pristine W/N fabric. Meanwhile, the peak heat release rate (PHRR) and total heat release (THR) of the obtained W/N-PP were reduced by 46.4% and 17.2%, respectively. Benefiting from the covalent linkage established via the Schiff base reaction between PP and the W/N fabric, the W/N-PP demonstrates superior washing durability. After 24 h of washing, the flame-retardant performance of W/N-PP was retained. Moreover, W/N-PP also retains the outstanding mechanical properties of pure W/N fabric. This facile and environmental process provided a powerful basis for technology and potential industrial applications.