Performance enhancement of fire retardant finish with environment friendly bio cross-linker for cotton

N-methylol dimethylphosphonopropionamide, commercially famous as Pyrovatex, is among the most commonly used fire retardant for cotton fabric. Unfortunately, Pyrovatex has the issue of releasing formaldehyde and further requires formaldehyde based cross-linkers to improve the fire retardancy, durability, and easy care performance. Consequently, toxic formaldehyde level is significantly increased in the treated cotton fabric. In our research, one bath, par-dry-cure method was used for the application and fixation of the fire retardant and cross-linker. Citric acid was used as a formaldehyde free cross-linking agent for cotton. Sodium hypophosphite (SHP) was used as catalyst for cross-linking of citric acid with cotton. In the presence of citric acid and catalyst with Pyrovatex, fire retardancy of the fabric was increased due to the enhanced bonding of Pyrovatex with cotton. In addition, phosphorous based catalyst SHP further increased the phosphorous in the system; consequently, fire retardancy is further improved. Therefore, only 200 g/L of Pyrovatex with citric acid and catalyst exhibited much better fire retardancy than using 400 g/L of the Pyrovatex alone. The crease recovery angle of the 200 g/L Pyrovatex treated fabric was raised from 188° to 239° when 80 g/L of citric acid was also incorporated into the recipe. Washing durability and tensile performance of the combination treated samples were better as compared to standard fabric.