1 R&D background
With the continuous development of textile technology, more and more anti-arc fabrics have appeared on the market, which mainly include finishing flame retardant and intrinsic flame retardant Two major categories. Intrinsically flame-retardant products have obvious performance advantages, so they have gradually replaced post-finished flame-retardant products. Commonly used fibers for inherently flame-retardant and arc-proof products include acrylic, flame-retardant viscose, aramid, etc. High-performance flame-retardant fibers such as polyimide, Polydelon, arylsulfone, and PBO are also used.
DL/T 320—2010 “Personal Arc Protective Equipment” “General Technical Requirements” stipulates the level of arc protection, fabric unit area quality and index requirements. ) and material breakopen threshold energy (Material Breakopen Threshold Energy, Ebt value) are clearly stipulated, and are required to meet these two indicators at the same time. The flame retardant performance of the product is only assessed on the afterburning time and damage length, and there is no mandatory requirement on the smoldering time. The American standard NFPA 70E-2018 “Workplace Electrical Safety Standard” is a protective clothing standard for electrical workers exposed to instantaneous arcs and related thermal injuries. It stipulates four levels of arc injury boundaries. ATPV value reflects that the strong effect of the fabric is greater than the thermal protection performance. When the thermal energy that produces second-degree burns is reached, the fabric does not break. Ebt value reflects that the thermal protection performance is better than the strength of the fabric , when the thermal energy to cause second-degree burns is not reached, the fabric ruptures. The smaller of the two indicators is used as the reported value. At the same time, the standard does not specify the smoldering time.
Neither the above national standards nor the American standards have any requirements for flame retardant products Requirements are made for smoldering indicators and comfort indicators. Based on market demand, the research and development of arc-proof fabrics is also developing in the direction of protection and comfort. For this reason, our company has developed a series of comfortable flame-retardant arc-proof fabrics that can meet DL/T 320-2010, NFPA 70E-2018, NFPA 2112 – 2018 “Industrial Fire Resistant Clothing Flame Retardant Performance Test Standard” and GB 8965.1-2009 “Protective Clothing Flame Retardant Protection Part 1 Flame Retardant Clothing” and other relevant requirements.
4.6 Comfort performance
The comfort indicators of materials include air permeability, moisture permeability, itch and elastic elongation, etc. It can be seen from the data in Table 2 that the air permeability of double-layer fabrics is significantly better than that of single-layer fabrics, which is nearly 5 times that of single-layer fabrics. This is because the double-layer fabric has an inner and outer layer structure. The two-layer structure is not dense and tight, and the gaps at the interweaving points are much more than that of a single-layer fabric. It can also be seen from the data in Table 2 that when the fabric structure changes, the moisture permeability also changes, but the difference is not significant. Generally speaking, the moisture permeability of double-layer fabrics is greater than that of single-layer fabrics; this is because for the same unit area of fabrics, the porosity of double-layer fabrics is greater than that of single-layer fabrics, and the mass of water vapor per unit area per unit time increases, and the moisture permeability increases. Larger quantities and improved comfort. The itch of fabric determines the quality of contact comfort, which mainly depends on the prominent hairiness of the fabric and its mechanical properties. When the materials are the same or comparable, the degree of itch is related to the structure of the fabric. The test data in Table 2 also shows that double-layer fabric has less itch and is more comfortable than single-layer fabric.
Elastic fabric is characterized by its stretchability and comfortable fit. It has become a mainstream product of clothing fabrics. Elastic elongation reflects the quality of sports comfort and is the most important functional indicator of elastic fabrics. The greater the elastic elongation of the fabric, the better the elasticity and the more comfortable it will be during movement. The test results in Table 2 show that Sample 1 and Sample 2 are inelastic, while Sample 3 and Sample 4 have a certain elasticity in the weft direction, and the elastic elongation is less than 20%. This is because spandex elastic yarn is added to the weft yarn of sample three and sample four, which is a one-way elastic fabric. Therefore, the fabric has good comfort, flexible movement and easy stretching after being made into clothing.
5 Conclusion
By testing and comparing the functional indicators and comfort indicators of the four samples, it can be seen that sample three and four can meet all the requirements of DL/T 320-2010. To develop comfortable flame-retardant and anti-arc fabrics, fabric specification design is very important. In order to achieve good functionality, the raw materials used and the blending ratio are very critical. Reasonable configuration of the blending ratio according to arc protection requirements can take into account both functionality and cost, especially adding a certain amount Polyimide helps improve the arc protection performance of fabrics, but its strength is low. Compared with the single-layer structure, the double-layer structure is more conducive to improving the arc protection performance and comfort of the fabric. The addition of elastic fibers helps improve the comfort of the fabric.
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