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Functional Fibers — Anti-UV Fibers
After everyday apparel meets people’s demands for comfort and aesthetics, consumers have gradually raised higher requirements for garment functionality. As one typical functional fiber, anti-UV fiber gains growing market attention. Therefore, this article introduces anti-UV fiber in terms of its properties, classifications and practical applications. To define it, anti-UV fiber refers to fibers with inherent UV shielding performance or those blended with anti-UV additives.
UV Resistance of Fibers
UV radiation reduces fiber tensile strength and may even cause molecular degradation. Meanwhile, different fibers respond differently to UV damage. For instance, acrylic fiber features outstanding inherent anti-UV performance. In contrast, polyamide and polypropylene have poor UV resistance. Hence, anti-UV additives or light stabilizers must be incorporated during production to manufacture functional anti-UV fibers.
Mechanism of Anti-Ultraviolet Radiation
When ultraviolet rays hit fabrics, part of the radiation is absorbed, part reflected and the rest transmitted through the material.
The sum of UV transmittance, reflectance and absorptance equals 100%. Accordingly, to protect human skin from UV damage, fabrics are engineered to boost their UV reflectance and absorptance. In this way, only minimal or nearly no ultraviolet rays can reach the skin.
Types of Anti-UV Fibers
Some fibers own intrinsic UV-blocking capability. For example, polyester gains natural UV resistance thanks to its benzene ring structure, and adding nano-ceramic powder further upgrades its anti-UV performance. Besides, acrylic ranks as an excellent anti-UV fiber. Its -CN groups absorb ultraviolet energy and convert it into dissipated heat. As a result, little UV energy remains inside the fiber to harm wearers.
Fibers loaded with anti-UV additives make up another major category. In general, most synthetic fibers feature weak natural UV resistance. Therefore, manufacturers mix a small dosage of anti-UV additives into fiber-forming polymers before spinning to produce anti-UV staple fibers.
1、Inorganic anti-UV additives consist of inorganic substances that scatter ultraviolet rays, including titanium dioxide, zinc oxide, talc, clay and calcium carbonate. These inorganic materials carry high refractive indexes and scatter UV radiation to stop it from penetrating human skin. Among them, titanium dioxide and zinc oxide have low UV transmittance, so most anti-UV fiber products prefer these two raw materials.
2、Next, organic anti-UV additives refer to organic UV absorbers capable of absorbing UV light between 270 nm and 400 nm, with benzophenone and its derivatives as typical examples.
Production of UV Resistant Fibers
1、Copolymerization Method: Manufacturers select proper UV absorbers to copolymerize together with monomers of fiber-forming polymers and generate UV-resistant copolymers, followed by spinning into finished anti-UV fibers.
2、Blending Method: Producers add powdered UV scatterers or absorbers during polymer synthesis or blend them directly for spinning. Alternatively, they first make anti-UV masterbatch before spinning. For example, Kuraray from Japan develops ESMO, a UV-shielding fabric fiber. The brand mixes roughly 0.1μm fine zinc oxide powder into polyester and produces anti-UV polyester staple fiber via melt spinning.
3、Coating Finishing Method: Workers apply single or blended UV absorbers and scatterers onto synthetic fibers via dipping or printing processes to obtain anti-UV fibers. Furthermore, to boost the washing and dry-cleaning fastness of UV additives, enterprises adopt resin microcapsule finishing technology. Specifically, organic UV absorbers are wrapped as core materials inside microcapsules, which effectively prevent the active ingredients from leaking out.
Uses of Anti-UV Functional Fibers
