For wear-resistant, cut-resistant and flame protective garments used in industrial high-temperature operations, apart from fiber substrates, flame retardants serve as key functional components to deliver fabric protection. Flame retardants interfere with combustion reactions through physical and chemical mechanisms, restrain flame spread, enable fabrics to self-extinguish rapidly upon contact with sparks or high-temperature heat sources, while preserving the fabric’s cut-resistant mechanical performance. Flame retardants of different types vary greatly in flame-retardant mechanism, wash resistance and smoke toxicity. During material selection, working conditions in industrial workshops must be considered to balance flame-retardant efficiency, wearing comfort and long-term stability.

　　Textile flame retardants fall into two major categories: intrinsic flame-retardant systems incorporated via fiber copolymerization and post-finishing flame retardants for fabrics. Intrinsic flame retardancy introduces flame-retardant monomers into the polymer backbone during fiber polymerization and spinning. The flame-retardant components become part of the fiber molecular structure and are not easily lost through washing or friction. Typical examples include aramid and flame-retardant modacrylic. No extra flame-retardant coating is required, delivering high durability suitable for heavy-duty industrial protection with repeated cleaning. By contrast, post-finishing flame retardants are applied onto fabric surfaces or embedded inside fibers via padding or coating processes, mostly used for flame modification of cotton substrates. They feature lower cost and flexible application, yet some grades have poor wash resistance; flame protection gradually degrades after repeated laundering.

　　Phosphorus-nitrogen intumescent flame retardants are widely adopted for garment post-finishing. When heated, their components react synergistically to promote fiber dehydration and carbonization, forming a dense porous char layer on the fabric surface. Acting as a thermal barrier, the char layer blocks oxygen, heat and outward diffusion of combustible volatiles to terminate combustion chain reactions. This type of flame retardant releases low volumes of smoke with relatively controllable toxicity, suitable for semi-enclosed working environments such as automotive workshops. Phosphorus catalyzes carbonization while nitrogen components release inert gas upon heating to dilute oxygen concentration and suppress flame propagation. However, formula ratios require precise tuning. Excess additives stiffen fabrics, reduce flexibility and weaken the suit’s cut and abrasion resistance.

　　Inorganic flame retardants are mainly metal hydroxides. They absorb heat through thermal decomposition and release water vapor to cool the substrate, while forming high-temperature resistant solid oxides covering fiber surfaces and blocking heat transfer. Such flame retardants feature good stability, low smoke and low toxicity, and are commonly compounded with phosphorus-nitrogen flame retardants. Their drawback is the high loading requirement, which strongly affects fabric hand feel. Used alone, they hardly maintain fabric softness. Therefore, they are rarely adopted as the primary flame-retardant system for protective garment fabrics, and are mostly applied for auxiliary coating modification to improve resistance against high-temperature splashes.

　　Traditional halogenated flame retardants offer high flame-retardant efficiency but release large amounts of corrosive, toxic smoke during combustion, so they are gradually phased out in industrial protective garment applications. Modern fabric formulation prioritizes low-smoke, halogen-free systems to protect operators’ respiratory safety under high heat. Flame retardant compounding technology is the core research focus. A single flame retardant can hardly satisfy multiple requirements including flame resistance, cut resistance and wash resistance. Compound formulations combining phosphorus-nitrogen and silicon-based components can complement each other, improving char density while reducing additive dosage and minimizing negative impacts on fabric mechanical properties.

　　Formulation design for flame retardants must consider not only flame resistance but also the cut resistance of protective suits. Excessive filling of yarn gaps by chemicals changes friction between fibers, making fabrics brittle and prone to cracking under cutting impact. During production testing, fabrics undergo both vertical flame tests and cut-resistance mechanical tests to verify that cut resistance does not drop significantly after flame-retardant treatment. Wash aging tests are also essential to simulate repeated cleaning cycles in workshops and detect changes in damage length and afterflame time after multiple washes, evaluating the fixation stability of flame retardants.

　　Environmental and safety assessment of flame retardants cannot be overlooked. Industrial protective garments stay in long-term skin contact, so chemicals must not contain irritants. Thermal decomposition products under high heat require strict control. In formulation development, low-migration flame-retardant ingredients are preferred to prevent chemical precipitation and skin irritation. Volatile organic compounds are controlled to reduce potential health risks within workshops.

　　In summary, flame retardants represent the core chemical components enabling thermal protection for cut-resistant flame protective fabrics. Different flame-retardant systems have their own pros and cons. Intrinsic flame retardancy provides superior durability, while post-finishing flame retardants support a wider range of substrates. When developing industrial protective garments, flame retardant formulations must balance flame-retardant efficiency, low smoke toxicity and wash resistance without compromising the fabric’s inherent cut and abrasion resistance. Proper selection of flame retardant types and compound recipes, verified through multi-dimensional tests for combustion, mechanical performance and aging, ensures stable protective performance against high-temperature sparks and safeguards operators.