Synthesis of triethylenetetramine phosphonate ammonium flame retardant and its application to cotton fabrics

A novel flame retardant, Triethylenetetramine phosphonate ammonium (TECHPA), containing phosphonate and ammonium phosphate groups, was synthesized and characterized by 1H, 13C, and 31P nuclear magnetic resonance (NMR) spectroscopy. The results showed that the Limiting oxygen index (LOI) of cotton fabric treated with 40 g/L TECHPA reached 36.8%, which remained at 31.1% after 50 laundering cycles. The infrared spectra and durability test results suggested that the flame retardant was grafted onto the cotton fibers through P–O–C covalent bonds. TG and cone calorimetry results indicated that the cotton fabrics treated with TECHPA flame retardant showed excellent flame retardancy. The SEM and XRD results suggested that the cotton fibers retained their original structures. For treated cotton fabrics, their stiffness increased slightly, their tensile strength decreased a little, and their crease recovery was greatly improved. No formaldehyde was detected in the cotton fabric after treatment. Overall, simultaneously introducing phosphonate and ammonium phosphate groups provided an effective method to increase the durability of treated cotton fabrics.