The scientific name of nylon fiber is polyamide fiber, which was originally the trade name of poly (hexamethylene adipamide) produced by DuPont Company, namely nylon 66. Polyamide fiber is the first commercial synthetic fiber product of synthetic polymer, which was invented by Caarothers of DuPont Company in the United States in 1937, thus opening the first page of synthetic fiber, and it is still the representative of polyamide fiber.
Carothers began to study polyester fiber from 1928. It has completed the basic research of polyester polymer of aliphatic diacid and diol, but its melting point is too low to be practical. However, due to this research, the brilliant success of today's PET polyester fiber has been established. Carothers's reaction of combining many molecules into new macromolecules is called polymerization. The condensation reaction that continues to combine into huge molecules is called polycondensation reaction. Under this idea, carothers began to study the synthesis of chain polymers from 1928, and synthesized chain polymer compounds such as polyamide, polyacetal and polyether through polycondensation. After a lot of basic research, in 1937, poly (hexamethylhexamethylene hexamethylenediamide), nylon hexachloride, was formed by polycondensation of hexamethylenediamine and adipic acid, which was the earliest commercialized polymer synthetic fiber. The first pair of nylon stockings was made in 1937, and DuPont immediately obtained the patent right in September of 1938, and established the first mass production factory under the trade name of "nylon" in 1939. At that time, the production capacity was 4,000 tons/year, and 1944 reached 25,000 tons and 65,434. 195 1 year, increasing to 65,000 tons. At the same time, Britain, France, Italy, West Germany and Japan have also set up factories to produce nylon 66. At the same time, schrack of IG Farben/basf proposed to use caprolactam as raw material in 1938. The abbreviation is CPL), which is a patent for synthesizing polyamide fiber, namely nylon 6, and obtained the trade name perlon. Later, with the development of polyamide fiber industry, fiber material researchers all over the world have studied various polyamide fibers, among which nylon 4-6, nylon 8, nylon 9, nylon 62, nylon 1 1 and so on are more mature. Poly (octylamide), nylon 9, nylon 12- methyl-hexamethylenediamine and nylon 1 1, although there are many kinds.
(A) the performance of polyamide fiber
The most outstanding advantage of polyamide fiber is its superior wear resistance, followed by its good elasticity, and its elastic recovery rate is equivalent to that of wool, and its specific gravity is 1. 14, which is second only to polypropylene (polypropylene, its specific gravity is less than 1) and higher than polyester fiber (its specific gravity is 1.38).
The disadvantage of polyamide fiber is poor optical rotation resistance. For example, if you are exposed to the sun for a long time outdoors, it is easy to turn yellow and the strength will drop. Compared with polyester yarn, its shape retention is poor, so the fabric is not straight enough and the fiber surface is smooth and waxy. In recent years, people have studied various improvement measures, such as adding anti-light agent to improve optical rotation resistance, or making special-shaped section to improve appearance and luster, and processing with DTY or ATY or other fibers.
Various properties of polyamide fiber are detailed as follows:
Abrasion resistance: The abrasion resistance of polyamide fiber is the best among all textile fibers. Under the same conditions, its wear resistance is 10 times that of cotton, 20 times that of wool and 50 times that of rayon. If 15% polyamide fiber is mixed into wool or cotton, its wear resistance is higher than that of pure wool or cotton.
2. Breaking strength: The breaking strength of long polyamide fiber for clothing is 5.0~6.4g/d, the breaking strength of high-strength industrial yarn is 7~9.5 g/d or even higher, and the wet breaking strength is about 85%~90% of the dry one.
3. Elongation at break: The elongation at break of polyamide fiber varies with different varieties. The elongation of high strength yarn is 10~25%, and that of ordinary clothing yarn is 25~40%. The elongation at break in wet state is about 3~5% higher than that in dry state.
4. Elastic recovery rate: the resilience of polyamide fiber is excellent. When the elongation of long fiber is 10%, its elastic recovery rate is 99%, while the elastic recovery rate of polyester is 67% and that of rayon is only 32% under the same conditions.
5. Fatigue resistance: Polyamide fiber has good fatigue resistance due to its good elastic recovery rate, which is close to polyester fiber but higher than other chemical fibers and natural fibers. Under the same experimental conditions, the fatigue resistance of polyester amide fiber is 7-8 times higher than cotton fiber and several times higher than viscose fiber.
6. Hygroscopicity: The hygroscopicity of polyamide fiber is lower than that of natural fiber and nylon fiber, but the hygroscopicity of synthetic fiber is higher than that of other synthetic fibers after PVA. When the temperature is 20 degrees Celsius and the relative humidity is 65%, the moisture content of nylon 66 is 3.4~3.8 and that of nylon 6 is 3.4~5.0, so the moisture absorption of polyamide 6 is slightly higher than that of polyamide 66.
7. Dyeability: The dyeability of polyamide fiber is more difficult than natural fiber and rayon, but it is still easier to dye than other synthetic fibers. Usually dyed with acid dyes.
8. Optical properties: Polyamide fiber has birefringence, which varies greatly with the elongation ratio. After full elongation, the longitudinal refractive index of nylon 66 fiber is 1.528, the transverse refractive index is 1.5 19, the longitudinal refractive index is 1.580, and the transverse refractive index is 6544.
9. Optical rotation resistance: the optical rotation resistance of polyamide fiber is poor, and the optical rotation resistance can be improved by adding an anti-light agent to the fiber during polymerization.
10, heat resistance: polyamide fiber has poor heat resistance. It turns yellow after 5 hours at150℃, softens at 170℃ and melts at 2 15℃. The heat resistance of nylon 66 is better than that of nylon 6, and its safe temperatures are 130 and 90℃ respectively, which can not reach the highest heat setting temperature.
1 1, chemical resistance: polyamide fiber has good alkali resistance, but poor acid resistance. Under normal room temperature adjustment, it can withstand soaking in 7% hydrochloric acid, 20% sulfuric acid, 10% nitric acid and 50% caustic soda, and the result is not corrosive. Therefore, polyamide fiber is suitable for anti-corrosion work clothes, which can be used as fishing nets.
(2) Performance comparison between nylon 6 and nylon 6/use of polyamide fiber
Nylon six and nylon six six fibers account for more than 95% of polyamide fibers. Their main performances are shown in the attached table. Although their physical properties are different, they are very similar in appearance, feel, strength and wear resistance in general use, and it is difficult to distinguish them from their plain fabrics and knitted fabrics, so they can often be replaced with each other. But considering the cost, nylon 6 is more dominant? The shrinkage rate of nylon six filament is slightly higher than that of nylon six filament, which is more suitable for knitted fabrics and pile fabrics? Nylon 66 is softer than nylon 66 because of its lower softening point, but it is more difficult to crimp, so the yarn crimp fastness processed by nylon 66 is better than nylon 66, so nylon 66 is more elastic and durable as pantyhose material? Because the melting point of nylon 66 is higher than that of nylon 66, the shrinkage rate can be lower, so the tire cord fabric used for tires is more resistant to high-speed driving and the tires can travel longer distances? In addition, the melting point of nylon 66 and polyester fiber is close to that of the fabric interwoven with polyester fiber, and it can be dyed with polyester fiber in the same bath at the same temperature, so the dyeing fastness of nylon 66 N/T fabric (nylon and polyester interwoven fabric) is better than that of nylon 66 N/T fabric?
Polyamide fibers can be made into long fibers or short fibers, and their uses are as follows:
1, long fiber: nylon long fiber can be used alone or interwoven with other fibers, and can also be false twisted into processed silk for knitting or flat weaving, which can be used in underwear for men and women, quilt cover fabrics, socks, raincoats, etc? In addition, polyamide fiber is used in the outer and inner layers of astronauts' coats to protect astronauts from the attack of meteorites in outer space with its high strength. Can be used for curtain cloth, shower curtain cloth, umbrella cloth in home decoration, fishing net, filter cloth, cable, tire curtain cloth, tire lining cloth and parachute cloth in industry? Because of its high strength, impact resistance and good wear resistance, the mileage of tires made of tire cord fabric is higher than that of nylon cord fabric. According to the experiment, polyamide tire cord fabric tire can travel about 300,000 kilometers, while nylon tire cord fabric tire can only travel about120,000 kilometers. The long polyamide fiber used in tire cord fabric is nylon 66, accounting for about 50% of the nylon 66 fiber consumption?
2. Short fiber: Compared with long fiber, polyamide short fiber accounts for about 265,438+0% in the United States. Among carpet fibers, short fibers account for more than 90%, while polyamide fibers account for 53% of carpet fibers. In addition, it can be blended with other fibers and used in socks, gabardine fabrics, validine fabrics, blankets, filter cloth and so on?
Performance comparison table of nylon 66 and nylon 6
Fiber variety nylon 66 nylon 6
Filament filament
Performance index common filament strong filament short fiber common filament strong filament
tearing strain
Cn/dtx is 4.94 ~ 5.65 (5.6 ~ 6.4), 5.65 ~ 7.68 (6.4 ~ 7.8), 4. 15 ~ 5.92 (4.7 ~ 6.7), 4.4 ~ 5.65 (5.0 ~ 6.4).
(g/denier) humidity is 3.97 ~ 5.29 (4.5 ~ 6.0), 4.86 ~ 6.89 (5.5 ~ 7.8), 3.44 ~ 5.03 (3.9 ~ 5.7), 3.70 ~ 5.21(4.2 ~) 59667.8666666666067
Knot strength (%), dry strength 80~90 60~70 80~90 70~80.
The dry-wet strength ratio (%) is 90 ~ 95.85 ~ 90.83 ~ 90.84 ~ 92.84 ~ 92.
Elongation at break% dry 26 ~ 4016 ~ 24 38 ~ 50 28 ~ 4216 ~ 25.
Humidity 30 ~ 52 21~ 28 40 ~ 58 36 ~ 52 20 ~ 30
The elastic recovery rate% (at 3% elongation) is 95 ~10098 ~10095 ~10098 ~10098 ~/00.
Young's coefficient (kg/mm? ) 235~3 18 373~447 100~250 200~450 280~5 10
Specific gravity 1. 14
Moisture absorption rate (%)20℃ air humidity 65% 3.4~3.8 3.5~5.0
Humidity 95% 5.8~6. 1 8.0~9.0
The heat-resistant softening point is 235℃, 150℃, the 5hr yellowing melting point is 260℃, the softening point is 180℃, and the melting point is 2 15~220℃. At the same time, it burns slowly without spontaneous combustion.
Weathering resistance, long-term exposure, strength reduction, yellowing, long-term exposure, strength reduction, yellowing, slightly worse than nylon 66.
When the thermal stability is zero, the temperature is 240℃, generally 193~ 195℃.
Optimum set temperature℃ dry state 130 93
Wet steam (saturated steam) > 140 137
In the water 98 95
Maximum ironing temperature℃ 205 150
(3) Development trend and application of new polyamide and nylon fibers.
Nylon fiber is superior to polyester fiber in softness, elastic recovery, wear resistance, alkali resistance, hygroscopicity and light weight, but its cost is about twice as high as that of polyester fiber, and nylon 66 is 20~40% higher than that of nylon 6. Therefore, whether nylon fiber can surpass polyester fiber in the future development depends on reducing raw material cost. Dupont Company of the United States and BASF Company of Germany, the leader of nylon 66, jointly researched and successfully developed the open-loop free technology, which can produce nylon 6 and nylon 66 raw materials at the same time. They are all made of butadiene. This new raw material process can save about one third of the cost, thus further reducing the price of nylon fiber and improving it. However, due to the high R&D cost of new process investment, it is estimated that it will take 9 to 10 years to break even, and then the price will be reduced. Therefore, nylon fiber products must develop in the direction of high added value and high performance in the near future in order to compete with polyester fiber? The development and application trends of new nylon fibers are summarized as follows:
1. conductivity: antistatic performance is one of the necessary properties in clothing and carpet applications. Polyether was added in the early stage, but it was not ideal at low temperature. Recently, conductive particles such as carbon black can be coated or removed from the inside to eliminate static electricity, which is rapidly expanding in carpet applications?
2. High strength and high modulus fiber: The cord used for tire cord fabric has the characteristics of high strength, high modulus and fatigue resistance. Due to the folded structure of polyamide molecules, the actual strength and modulus of nylon 66 and nylon 6 polyamide fibers only reach 65,438+00% of the theoretical value, so the development of liquid crystal spinning and the "kevler" fiber developed and mass-produced by Dubang Company are an aromatic polyamide fiber.
3. Silk-like material for clothing: the fiber for clothing requires a comfortable and delicious appearance. In addition to the antistatic properties mentioned above, it is also necessary to improve gloss, softness and hygroscopicity. The gloss can be improved by increasing the addition of matting agent titanium dioxide to 2-3% to achieve the matting effect similar to that of cotton fiber, which has luster similar to that of spun silk, bright particles and triangular or star-shaped cross section. Because the elastic recovery rate of nylon fiber is better than that of polyester fiber, with nylon blended fibers with different shrinkage rates (such as 40d/68f+30d/ 12f with high shrinkage), fine denier of 0.6d appears on the fabric surface after dyeing and finishing, so the fabric has soft luster and soft hand feel. Fine denier improves the softness of the fabric, while mixed weaving with different shrinkage improves the richness and uniqueness of the fabric. So the fiber processing of nylon fiber must develop towards this trend in the future?
4. Lightweight new nylon material: the proportion of nylon fiber is lighter than that of polyester, so the fabric has the characteristics of lightness. If hollow cross-section spinning is used, the fiber will have a lighter feeling, and the processed fiber will have a better fluffy feeling and thermal insulation. Therefore, how to develop high hollow ratio nylon fiber is an important research and development topic for nylon fiber factory.
5. Elastic new composite material: the two-component composite fiber composite spinning with pu elastic fiber as the core and nylon as the sheath has the advantages of high elasticity of pu and light weight of nylon, and will naturally curl after heat treatment, so its fabric has good elastic comfort and natural and transparent skin color effect, and is suitable for women's underwear and super elastic pantyhose?
6. Waterproof and breathable new material: nylon 6 or nylon 66 and polyester are compounded and spun, and its cross section is orange cake-shaped, so-called segmented shape. With the increase of the number of segments, the waterproof and breathable properties of the fabric will also increase, and the current production process can reach 64 segments.
7. Antibacterial and deodorizing materials: A special ceramic material is mixed in the nylon spinning process, which will release a small amount of silver ions and achieve a good antibacterial effect. By mixing, the durability of antibacterial agents can be improved. After processing, weaving, dyeing and finishing, the antibacterial properties of the fiber will not be destroyed, and the antibacterial effect can still be maintained after at least 50 washes?
8. Health care materials: nylon fibers are mixed with ceramic particles that can release far infrared rays, which can improve the warmth and comfort of fabrics. Far infrared rays are electromagnetic waves with a wavelength of 4 to 50 mm, which can promote blood circulation and keep warm?