Chemical fiber is a fiber with textile properties that is made from natural polymer compounds or synthetic polymer compounds as raw materials through the preparation of spinning solution, spinning and post-processing. Common textiles, such as viscose cloth, polyester khaki, nylon stockings, acrylic wool and polypropylene carpets, are all made of chemical fibers.
Since the first artificial silk was extracted in the 18th century, chemical fiber varieties, fiber-forming methods and spinning Silk technology has made great progress. It is widely used in the manufacture of clothing fabrics, filter cloths, conveyor belts, hoses, ropes, fishing nets, electrical insulated wires, medical sutures, tire cord fabrics and parachutes, etc.
Short fibers of man-made fibers are always called “fibers” (such as viscose fiber, rich fiber), synthetic Short fibers are always called “fiber” (such as nylon, polyester). If it is filament, add “silk” or “filament” at the end (such as viscose, polyester, acrylic filament). Or change “Lun” and “Fibre” to “Silk”.
Man-made fibers
Chemical fiber made from natural polymer compounds (such as cellulose). Man-made fibers mainly include viscose fiber, nitrate fiber, acetate fiber, cupro ammonium fiber and artificial protein fiber.
The main varieties of man-made fibers are:
⑴ Viscose fiberIn 1848, J. Mercer discovered that the sensitivity of chemical reactions increased after cotton cellulose was impregnated with concentrated alkali. . After that, the British C. Cross and E. Bevin used carbon disulfide and alkali fiber to obtain soluble cellulose xanthate, thereby producing viscose fiber. Later, the centrifugal tank winder appeared, which provided the conditions for industrial production of viscose fiber.
⑵ New viscose fiberWith the development of science and technology, the output and quality of man-made fibers continue to increase. Since then, several new viscose fibers with outstanding properties have been developed. Among them are:
① High wet modulus fiberThe structure is close to cotton The cross-sectional shape of the fiber is close to that of wool. The strength ratio between wet and dry conditions is 70%. It has small water absorption and low alkali solubility. In the early 1950s, Japanese Masayuki Ishikawa improved the viscose fiber preparation process conditions and stretched the nascent wet silk strips at high times to obtain high-strength viscose fiber, which was named “tiger kapok”. This fiber combines the advantages of cotton and viscose.
② Super viscose fiber is a series of high-strength, Viscose fiber with high toughness and fatigue resistance. This kind of fiber has small grains and the skin structure accounts for more than 60% of the cross-section, and some even reach 100%. Therefore, the fiber has high strength and fatigue resistance and can be used to make automotive tire cords.
③ Permanently crimped viscose fiberUse viscose fiber to have a sheath core The characteristics of the structure and the adoption of appropriate process conditions make the cross-sectional shape of the fiber asymmetric and the distribution of the thickness of the cortex uneven, resulting in different internal stresses on the cross-section, thereby causing the fiber to form a curled shape.
⑶ Nitrate fiber Also known as nitrate rayon. In 1855, the British nitrated cellulose, dissolved it into glue, and extruded it into silk. In 1884, the denitrification method was successfully researched, and the production of rayon using the nitric acid method was officially put into production.
⑷ Acetate fiberCombine cotton linters with glacial acetic acid as the The main reagent is acetified to form cellulose acetate, which is dissolved in a slurry of chloroform and spun to obtain triacetate fiber. If cellulose acetate is partially saponified, cellulose acetate soluble in acetone is obtained. The fiber obtained after spinning is called diethyl acetate fiber.
⑸ Cuprammonium fiber Use tetraammonium copper hydroxide solution as solvent , rayon made by dissolving cotton linters into slurry spinning. The silk quality is fine and beautiful, but the cost is high.
⑹ Artificial protein fiber The British were the first to study extraction from animal glue Protein makes artificial protein fibers. In 1935, someone in Italy experimented with extracting casein from cow’s milk to make artificial wool. Since then, some countries have succeeded in producing artificial fibers from soybean protein and peanut protein. Due to problems with practical properties and manufacturing costs of this type of fiber, very little is produced.
2. Synthetic fibers
Synthetic fibers are chemical fibers made from artificially synthesized polymer compounds. Commonly used synthetic fibers include polyester, Nylon, acrylic, chlorine, vinylon, spandex,Deformation occurs and prevents relative slippage between molecules, thus giving the fiber higher resilience. Elastic fibers can be used to make tights, swimsuits, elastic bands, sock cuffs, surgical socks, etc.
⒍ Functional fiber: Change the shape and structure of the fiber to have a certain Special functions, such as making cuprammonium fiber or polyacrylonitrile fiber into a hollow form, can be used medically as a material for artificial kidney dialysis against blood viruses. Polyamide 66 hollow fibers are used as seawater desalination dialyzers, and polyester hollow fibers are used as reverse osmosis equipment for concentrating, purifying and separating various gases.
⒎ Inorganic fiber:The development of modern industry requires high temperature resistance and high temperature resistance. Special materials with strength, electrical insulation and corrosion resistance. For this reason, people have tried to produce a series of inorganic fibers, such as glass fiber, aluminum silicate fiber, boron fiber, potassium titanate fiber, ceramic fiber, quartz fiber, silica fiber, etc. Glass fiber can be used as flameproof, anti-corrosion, anti-radiation and plastic reinforcement materials. It is also an excellent electrical insulation material. Potassium titanate and aluminum silicate fibers are insulating materials at high temperatures of 1200°C.
5. Modified fiber
Although synthetic fibers have good physical and mechanical properties, due to their smooth surface, poor water absorption and dyeability, the use of fabrics Does not perform as well as natural fiber fabrics. In order to make synthetic fibers have the characteristics of natural fibers, research on the modification of synthetic fibers was carried out in the 1950s, mainly using physical or chemical methods to improve the hygroscopic, dyeing, antistatic, anti-flammable, anti-fouling, anti-pilling and other properties of synthetic fibers. At the same time, The variety of chemical fibers has also been increased.
⑴ Chemical modification:Mainly include grafting denaturation and copolymerization denaturation There are three methods including chemical treatment and denaturation of fibrils.
⑵ Physical modification: Mainly by changing the shape of the spinneret Spun special-shaped fibers; using the thermoplasticity of synthetic fibers to change straight fibers into curled deformed fibers (such as bulked yarn and elastic yarn); extruding two types of polymer fluids with different properties from the same spinneret Made of composite fibers.
