A combination of citric acid and sodium hypophosphite (CA and SHP, two inorganic chemicals) was tested as an alternative cross-linker for application of Pyrovatex CP New (an organophosphorus PIN flame retardant for textiles), for lyocell fabric.
Lyocell is a cellulose microfibre with environmental, moisture transport, aesthetic and comfort properties, but which is readily flammable. The CA-SHP effectively replaced the standard cross-linker used with Pyrovatex (methylated melamine), in both cases also with phosphoric acid, showing in most cases good fire performance even after ten washes, with a 75% reduction in formaldehyde release. Low formaldehyde is required by regulation in some countries and by ecolabels such as OEKO-TEX 100.
“Citric acid based durable and sustainable flame retardant treatment for lyocell fabric”, Mengal et al., Carbohydrate polymers 153 (2016) 78–88 http://dx.doi.org/10.1016/j.carbpol.2016.07.074