Fire hazards are everywhere. Tens of thousands of fires occur in my country every year. Textile materials are widely used in clothing and household life. In many cases, textiles become ignition sources, releasing toxic gases and directly endangering human health. In certain special situations, such as the work clothes worn by firefighters, steelworkers, welders, chemical plant workers, oil refinery workers, and oilfield drilling workers, as well as the combat uniforms of military personnel, flame-retardant properties are required. Furthermore, the flame-retardant properties must be free of molten droplets to prevent secondary burns. In many civilian applications, such as decorations in hotels, auditoriums, and stages, as well as seat covers, curtains, bedding, and children’s clothing in vehicles like airplanes, trains, and automobiles, flame-retardant properties are also essential.
History of Flame Retardant Technology Development
China’s flame retardant technology began in the 1950s with research on temporary flame-retardant finishing of cotton fabrics, but development was slow. Durable flame-retardant pure cotton textiles only emerged in the 1960s. In the 1970s, flame retardants were developed, and research began on flame retardant technology for synthetic fibers and blended fabrics. In the 1980s, flame-retardant fabrics entered a new development period, with many organizations developing flame retardants and finishing technologies for cotton, polyester, and blended fabrics, as well as flame-retardant synthetic fibers. Overall, flame-retardant fiber products are in a stage of rapid development and research.
Definition
Fibers that do not burn upon contact with a heat source (such as glass fiber), or whose combustion reaction is incomplete, producing only a small flame (such as chlorofiber), and whose flame extinguishes itself relatively quickly after the heat source is removed, can be called flame-retardant fibers. Based on the limiting oxygen index (LOI) value of the fiber, it is generally considered that an OX < 22 is flammable, an OX between 22 and 27 is combustible, and an OX > 27 is flame-retardant.
Type
There are many types of flame-retardant fibers, and extensive research has proven that fabrics made from flame-retardant fibers possess certain advantages. Below, we will introduce different types of flame-retardant fibers and their applications.
- Flame-retardant Viscose Fiber The main methods for flame-retardant modification of viscose fibers include grafting, blending, and copolymerization. Among these, blending is currently a commonly used method. Flame-retardant viscose fibers do not burn when exposed to fire, forming a dense carbonized layer that protects the fiber from oxygen, eventually extinguishing itself. Because cellulose fibers themselves do not melt, flame-retardant viscose fibers also have a non-drip effect.
Flame-retardant viscose fiber can be woven into comfortable apparel fabrics for underwear, sleepwear, and bedding. It can also be blended with various flame-retardant fibers—acrylic chlorofiber, chlorofiber, flame-retardant polyester, etc.—and such blends can be used in interior decoration and accessories.
Nomex fiber
Nomex, produced by DuPont in the 1960s, has a limiting oxygen index of around 32. It possesses permanent flame retardancy, does not melt at high temperatures, and exhibits excellent thermal stability. Nomex also boasts excellent chemical resistance, good mechanical properties, a soft hand feel, good spinnability, and excellent radiation resistance. It has wide applications in fire-resistant workwear and fire suits.
PSA (Pyramidal Sulfone)
Belonging to the para-aramid series, it has a limiting oxygen index of 33, is flame-retardant, self-extinguishing, and rarely exhibits smoldering or afterburning. The smoldering and afterburning time, damage length, and other indicators of aramid fiber can meet the flame-retardant requirements of various thermal protective clothing.
Flame-retardant polyester fiber
There are three main methods for weaving flame-retardant polyester fibers: copolymer flame-retardant modification, blend flame-retardant modification, and flame-retardant finishing. The fibers do not burn when exposed to fire, but they will still melt and produce molten droplets.
FBI Fiber
Polybenzimidazole (PBI) fiber is a non-thermoplastic flame-retardant fiber developed in 1963 by the American Aerodynamics Materials Laboratory and Celanese Corporation. It does not burn in air, has a limiting oxygen index as high as 40, and shrinks only 10% after prolonged exposure to a 600°C flame, while the fabric remains intact and soft. It possesses good chemical resistance, moisture absorption, and a pleasant hand feel, as well as good textile processing properties, making it highly suitable for use in firefighting clothing.
Flame-retardant acrylic fiber
Acrylic fibers can be modified through copolymer flame retardant modification, blend flame retardant modification, thermal oxidation, flame retardant finishing, and post-treatment flame retardant modification. Currently, most industrial products are woven using the copolymer method.
In Conclusion
Over the past decade, China has seen a surge in the construction of high-rise residential buildings and hotels, leading to increasingly stringent requirements for the flame retardancy of interior decoration materials. Some industrialized countries established flame retardant regulations for textiles long ago, stipulating that curtains and draperies in public places such as theaters, hospitals, and hotels, as well as clothing fabrics for the elderly, children, and disabled, must meet certain flame retardant standards. The development and application of flame-retardant fibers and textiles are receiving increasing attention from society.
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