Flame retardant textile back-coatings. Part 2. Effectiveness of phosphorus-containing flame retardants in textile back-coating formulations

Selected phosphorus-containing flame retardants, including some intumescent s, have been formulated with selected resins and applied as back-coatings t o both cotton and cotton-polyester (35:65) blended fabrics. While all formu lations raise the limiting oxygen index, only those based on ammonium polyp hosphate and a cyclic phosphonate enable samples to pass a small-scale vers ion of the simulated match test, BS5852: 1979, Source 1. As expected, the b ack-coatings containing intumescents promoted higher levels of char formati on, but these did not reflect in their performance to the match test where most incurred failures. Thermogravimetric analysis suggests that the more effective flame retardant s as exemplified by ammonium polyphosphate, are those which liquefy by melt ing and/or decomposition well below 300 degreesC. It is proposed that this enables wetting by these products of the back face of the fabric and their diffusion to the front face where, as the temperature rises towards 300 deg reesC, char formation occurs before ignition of surface fibres can take pla ce. (C) 2000 Society of Chemical Industry.