Synthesis and application of a sulfur-containing phosphoric amide flame retardant for nylon fabric

A sulfur-containing flame retardant (SFR) was synthesized from polyphosphoric acid, epoxy chloropropane, and thiourea. Using a water-soluble isocyanate-terminated (WIT) cross-linker, the flame retardant was applied as a flame-retardant finishing on nylon fabric. WIT is a compound that not only cross-links SFR and nylon cellulose but also contains no formaldehyde. Comparisons of the main performances of SFR with those of N-methyloldimethylphosphonopropionamide (known as Pyrovatex CP') and a bicyclic phosphonite (known as Antiblaze 19T') indicate that the presence of sulfur in SFR plays a crucial role in decreasing the flammability of the nylon fabric. The limiting oxygen index value and damaged carbon length of the finished nylon fabric were 29.4% and 5.7cm, respectively, when the concentrations of SFR and WIT were 200 and 40g/L, respectively, and the baking temperature and time were 150 degrees C and 3min, respectively. After 10 laundry cycles, the fabric still retains some flame retardancy. Copyright (c) 2016 John Wiley & Sons, Ltd.