Water-soluble cyclophosphazenes provide effective, wash-resistant fire resistance to 50:50 “nyco” blend fabric. The novel phosphorus-nitrogen PIN compound, hexa (allylamine) cyclotriphosphazene (CPZ), see Mayer-Gall et al. in pinfa Newsletter n°106, was reacted with derivatives of glycerol or thioglycerol to introduce water-soluble moieties. Loading of 30% was applied to the textile in aqueous solution at pH4, using a melamine derivate as cross-linker, followed by curing at 120 °C. The treated textile showed LOI (Limiting Oxygen Index) increased from 20% (pure nyco) to 23% (glycerol derived) or 27.5% (thioglycerol derived) and passed the ISO 15025 flammability test, self-extinguishing performance even after 10 wash cycles at 80 °C. Analysis suggested that sulphur (thioglycerol derived) was acting in the gas phase and phosphorus was mainly active in the condensed phase, resulting in increased char formation.
“Water-Soluble Cyclophosphazenes as Durable Flame-Retardant Finishes for Nylon/Cotton Blend Fabrics”, O. Zilke et al., ACS Appl. Polym. Mater. 2022, https://doi.org/10.1021/acsapm.2c01257