Flame retardant modacrylic fiber is a high-performance functional textile fiber produced by copolymerizing acrylonitrile with flame-retardant vinyl monomers. Unlike conventional acrylic fiber, which is highly flammable and releases massive smoke and toxic gases during combustion, this modified fiber locks flame-retardant elements on its molecular chains to achieve permanent and stable flame resistance. It mainly includes two categories: modacrylic fiber and vinylidene chloride-acrylic fiber. Featuring a high limiting oxygen index, non-melting and non-dripping carbonization performance, as well as low smoke and low toxicity, the fiber inhibits combustion by absorbing heat and forming a dense protective char layer to isolate oxygen and heat transfer. In addition, it inherits superior softness, bulkiness, dyeability and chemical stability, and some grades deliver excellent UV resistance and thermal insulation. Proper maintenance including low-temperature washing, drying and ironing,