Synthesis of a novel flame retardant phosphorus/nitrogen/siloxane and its application on cotton fabrics

A novel flame retardant containing phosphorus, nitrogen and silicon was synthesized in this study. Its structure was characterized by Fourier transformed infrared spectrometry and 1H nuclear magnetic resonance. The flammability and thermal stability of the cotton fabric treated by the flame retardant was systematically evaluated by the limiting oxygen index (LOI) method, vertical combustion method and thermogravimetric analysis (TGA). The breaking strength, tearing strength and wrinkle recovery angle (WRA) of the treated fabric were also investigated to analyze the effects of the flame retardant on the original cotton fabric. The optimal parameters of the anti-flame finishing process conditions were flame retardant phosphorus/nitrogen/siloxane of 200 g/L, catalyzer of 25 g/L, curing temperature of 170℃, curing time of 3 min, pH 5.The results showed that the treated fabric was an excellent flame retardant, LOI was improved from 18.0 to 27.1 and its anti-crease property was obviously improved, as WRA increased from 80° to 98°. The TGA curves also suggested that the flame retardant had a good ability of char formation due to the synergistic effect of phosphorus, nitrogen and silicon. Through the wash fastness analysis, the LOI value of the treated sample remained at 23.3 compared with 18.0 of the untreated sample, which meant a durability flame-retarding effect.