Preparation of flame-retardant/dyed cotton fabrics: flame retardancy, dyeing performance and flame retardant/dyed mechanism

An environmentally friendly phosphorous-nitrogen synergistic flame retardant, 6-monochloro-1,3,5-triazine-4-p-aminobenzenesulfonate-2-methylphosphinic acid dimethyl ester (CTSGP), was synthesized and applied to improve the thermal stability of cotton fabrics. The chemical structure of GTSGP was analyzed by Fourier transform infrared spectroscopy, and the appearance of its group characteristic peaks indicated that the compound was successfully prepared. The flame retardant reacted with the hydroxyl groups of cotton fabrics to constitute covalent bonds that bunch firmly to the surface. The flame retardancy of the treated cotton fabrics was evaluated by the limiting oxygen index (LOI) and vertical flammability test. The results showed that the LOI value of cotton fabrics treated by CTSGP increased from 18.0 to 29.0%, the length of char residue was only 62 mm without after-flame time and after-glow time. The thermogravimetric and cone calorimetry test results showed that the char-forming ability of the treated cotton fabrics was significantly improved and the peak heat release rate decreased from 144.23 to 11.64 kW/m2. Besides, the mixed dyeing behavior of GTSGP and reactive dyes showed that the cotton fabrics can obtain the ideal color and flame retardant performance at the same time. The color fastness to wet rubbing of the flame-retardant/dyed fabrics reaches 4, and the softness is slightly improved compared with untreated cotton fabrics. The non-flammable nitrogen gas and organophosphate carbon layer generated by the treated cotton fabrics during combustion contribute to the flame resistance of fabrics. A reactive phosphor-nitrogen flame retardant (CTSGP) was synthesized and applied to cotton fabrics to obtain excellent flame retardant property.