Eco-friendly coating based on an intumescent flame-retardant system for viscose fabrics with multi-function properties: Flame retardancy, smoke suppression, and antibacterial properties

Ammonium phytate and chitosan were chosen as eco-friendly flame retardants to improve the flame retardancy and antibacterial properties of viscose fabrics. The flame-retardant viscose fabrics exhibited sharp improvements in thermal stability at the higher temperature zone, and 2BLviscose retained 39.0% char residues at 700 °C. 2BL/viscose obtained a limiting oxygen index value of 29% and self-extinguished in the vertical flame test. The fire behaviors of the flame-retardant viscose fabrics were also enhanced; even the addition of CS decreased the total smoke production value from 0.6 to 0.3 m2. Flame-retardant viscose fabrics released less flammable substances and more H2O, resulting in combustion choking. Meanwhile, the flame-retardant samples formed stable char residues, which were mainly constituted by graphite. Meanwhile, the viscose fabrics coated with CS/AP exhibited excellent antimicrobial properties, and 2BL/viscose obtained a 99.99% antibacterial rate for both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli).