A brief analysis of newly developed flame-retardant viscose/flame-retardant acrylic textile products
The promotion and application of fire-retardant fabrics are restricted by the fire resistance, functionality, comfort and price of existing fire-retardant fabrics. This article introduces the application of newly developed fire-retardant viscose/fire-retardant polyacrylonitrile fabric products in this field. Achievements achieved.
1 Market research and product development positioning
1.1 Market demand for fire-resistant fabric products
Fire-retardant fabrics have been promoted rapidly and are now widely used in high-rise buildings, hotels, cinemas, hospitals, home decoration, as well as interior decoration of airplanes, ships, trains, and automobiles and the protection of special personnel. At the same time, our country is also formulating and implementing regulations and measures for the mandatory use of fire-resistant fabrics. For example, the national standard GB20286–2006 “Combustion Performance Requirements and Labeling of Fire Protection Products and Main Components in Public Places” stipulates that after July 1, 2008, the Fire Protection Bureau of the Ministry of Public Security strictly requires that any product that does not meet the requirements of the standard must be inspected by the fire protection department. Any project that fails the acceptance inspection or fire inspection will not be approved.
According to expert predictions, for protective work clothing alone, my country’s metallurgical and firefighting departments need 400,000 sets of fireproof clothing every year, and hydropower, nuclear industry, geological and mining and other departments need 2 million sets of fireproof clothing, plus military uniforms and other other needs fireproofing Serving 3 million sets is a large market capacity.
1.2 Research Focus on Fire-Retardant Fabric Products
The fire resistance, functionality, comfort and price of fire-retardant fabrics are still the keys to their mass application. The early research and development in our country were fire-retardant fabrics made from ordinary fabrics after fire-retardant finishing. They did not have permanent fire resistance because they were not resistant to cleaning. Some fire-resistant synthetic fibers developed later, although they have permanent fire resistance, their limiting oxygen index also reached a good level. , but the wearability is poor, and it is easy to produce molten drippings in the event of a fire, which will cause secondary damage to on-site personnel; fabrics made of Nomex1313 fiber have particularly good fire protection effects, but are expensive and stained Difficult, generally used for extraordinary products with high requirements. In summary, the large number of applications of fire-retardant fabrics are restricted by the fire resistance, functionality, comfort and price of existing fire-retardant fabrics.
1.3 Development and research positioning of fire-resistant fabrics
The new fire-resistant fiber product of a long-term cooperative unit of our company, fire-resistant viscose fiber, has passed the appraisal. This product is a new high-tech fiber material with fireproof and droplet resistance developed based on the research results of the national “863” program. Adopting a new generation of fire protection technology – sol-gel technology, the inorganic polymer fire retardant exists in an interpenetrating network state in the organic macromolecules of the viscose fiber, which not only ensures the excellent physical properties of the fiber, but also achieves low smoke, It is non-toxic, does not melt and drip but only carbonizes. It has a self-extinguishing effect. After carbonization, it can still maintain the original shape of the fiber and avoid secondary damage to personnel caused by high-temperature melt dripping. The physical properties of this fireproof viscose fiber are similar to those of general viscose. The fibers are similar, have good moisture absorption and breathability, and are easy to color. The fabric has good hand feel and wearing comfort. The fiber limiting oxygen index LOI is greater than 28%, and has permanent fire resistance. The waste can be naturally degraded and is green and environmentally friendly. The company decided to take the lead in developing this fire-resistant fiber fabric product.
Through careful research and screening, we selected fire-resistant polyacrylonitrile fiber and fire-resistant viscose fiber blended chemical fiber fabrics. The limiting oxygen index of fireproof polyacrylonitrile fiber fiber is 28% to 34.6%. The fireproof effect will not change due to the cleaning, ironing and wear of the fabric, and it is permanently fireproof. It is difficult to burn fire-resistant polyacrylonitrile fiber or its fabric, that is, it cannot maintain combustion, nor can it spread flames or molten droplets. When the flame leaves, it will burn out on its own. When directly ignited, there will be no molten droplets to char, thus forming an additional fire protection Layer; The physical properties of fireproof polyacrylonitrile fiber are very close to those of ordinary polyacrylonitrile fiber. The specific gravity is greater than that of ordinary polyacrylonitrile fiber, similar to wool, and the moisture regain is less than 2%. It has the characteristics of high strength, good elasticity and dimensional stability; It also has particularly good coloring properties and strong chemical resistance, including most inorganic acids and salts, organic acid oxidants and organic chemicals, except dimethylformamide, dimethylacetamide, dimethyl Except for sulfoxide and acetone, most organic solvents cannot dissolve it. It is better than most natural fibers and man-made fibers and has good protective function.
The common features of the two fire-resistant fibers are: (1) The limiting oxygen index LOI is greater than 28%, which is a flame-retardant fiber; (2) It has low smoke, non-toxic, does not melt and drip when exposed to fire, and only carbonizes, sparing people. Secondary damage; (3) Resistant to cleaning, with permanent fire resistance; (4) Easy to color, bright color, good coloring performance; (5) Physical properties are similar to natural fibers, fireproof viscose is similar to cotton, fireproof polypropylene Nitrile fiber is similar to wool and has good skin-friendly properties.
The differences in the performance of the two fibers are: (1) Fire-resistant viscose fiber has good hygroscopicity, with a moisture regain rate of 12% to 14%, while fire-resistant polyacrylonitrile fiber fiber has low moisture absorption, with a moisture regain rate of 1.2% to 2.0%; (2) ) Fireproof polyacrylonitrile fiber fiber has strong chemical resistance; (3) Fireproof polyacrylonitrile fiber fiber has a higher limiting oxygen index LOI (up to 34.6%). The two types of fire-resistant fibers have outstanding advantages in common and complement each other; their differences complement each other and complement each other; they are suitable for reasonably designed blended chemical fiber fabrics based on different needs.Ratio (combined with price factors at the same time). For example, if underwear needs to be moisture-absorbent, breathable, and skin-friendly, then the mixing ratio of fire-retardant viscose should be higher; for protective clothing, if it requires good fire-retardant effect, good protective function, and good shape retention, then the mixing ratio of fire-retardant polyacrylonitrile fiber should be higher (at the same time , the price and cost are also lower). 2 Product trial production and process technology design 2.1 Selection of fire-resistant fiber raw materials Fire-resistant adhesive: 1.67 dtex×40 mm, dry strength 2.18 cN/dtex, wet strength 1.12 cN/dtex, elongation at break 14.7%, LOI≥ 28%. Fire-resistant polyacrylonitrile fiber: 1.67 dtex×40 mm, breaking strength 2.10 cN/dtex, elongation at break 34.65%, LOI 34.2%. 2.2 Design of typical mixed ratio spinning yarn products (see Table 1)
2.3 Fabric design with different tissue specifications (see Table 2) After research and experiments, we have grasped the technological characteristics of two kinds of fire-proof fiber spinning and weaving, and successfully produced the series of spinning yarns listed in Table 2 and Table 3 and fabrics.
3 Fire performance inspection results and analysis
The oxygen limiting index of three fabrics tested by the National Fire Equipment Quality Supervision and Inspection Center is 32.4% ~ 32.5%, and the combustion characteristics are carbonization, which meets the requirements of GB/T 5454 fabric fire protection level one oxygen index ≥ 32.0%; vertical combustion The legal damage length is 87~98 mm, the warp and weft afterburning time is O, and the smoldering time is 0. It reaches the GB/T 5455 fabric fire protection level one damage length ≤ 150 mm, afterburning time ≤ 5 s, and smoldering time. The time is ≤5 s, and the burning drippings do not cause the burning and smoldering requirements of the absorbent cotton. The test results are shown in Table 3.
4 Conclusion
(1) The developed fabric complies with the technical requirements for fireproof Bl level combustion performance of fireproof woven fabrics of the People’s Republic of China GB 17591-1998; (2) The fireproof viscose mixing ratio ranges from 30% to 70%, and the corresponding fireproof polypropylene The fire-proof performance of this series of products is not significantly affected by changes in the nitrile fiber mixing ratio from 70% to 30% or changes in fabric tissue specifications. The fire-proof performance of this series of products is stable.
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