Spandex fiber is the abbreviation of polyurethane fiber, and its trade names are Lycra (USA, UK, Netherlands, Canada, Brazil), Neolon (Nylon, Japan), Dorlastan, Germany, etc. First, 1937 Bayer Company in Germany succeeded in research, and 1959 DuPont Company in the United States began industrial production. At present, there are nearly 40 factories and 7 production lines, with an annual total output of about 654.38+10,000 tons. The existing production capacity in China is about 1 10,000 tons. Spandex is a kind of synthetic fiber, which contains more than 85% polyurethane.
There are two kinds of spandex fibers, one is a polymer with aromatic diisocyanate and hydroxyl-containing polyester segments (polyester spandex for short), and the other is a polymer with aromatic diisocyanate and hydroxyl-containing polyether segments (polyether spandex for short). Spandex fiber, elastic polyolefin fiber and elastic composite fiber are collectively called elastic fibers.
Synthetic fiber with high elongation at break (above 400%), low modulus and high elastic recovery rate. China trade name of multiblock polyurethane fiber. Also called elastic fiber. Spandex has high elongation (500% ~ 700%), low elastic modulus (200% elongation, 0.04 ~ 0. 12g/ denier) and high elastic recovery (200% elongation, 95% ~ 99%). In addition to high strength, other physical and mechanical properties are very similar to those of natural latex yarn. It is more resistant to chemical degradation than latex wire, with moderate thermal stability and softening temperature above 200℃. Most dyes and finishing agents used for synthetic fibers and natural fibers are also suitable for dyeing and finishing spandex. Spandex is sweat-resistant, seawater-resistant, resistant to all kinds of dry cleaners and most sunscreen oils. Long-term sun exposure or chlorine bleach will also fade, but the degree of fading varies with the type of spandex.
The reason why spandex fiber has such high elasticity is that its polymer chain consists of low melting point amorphous "soft" segments as matrix and high melting point crystalline "hard" segments embedded in it. The molecular chains of flexible segments are crosslinked to form a certain network structure. Because the interaction between molecular chains is very small, they can expand and contract freely, resulting in great elongation. The molecular connecting force of the rigid segment is relatively large, and the molecular chain will not extend indefinitely, so the elasticity is high. Most of the cross sections of radon nylon wires are dog-bone-shaped, and some wires have smooth or serrated surfaces. The breaking strength is the lowest among all textile fibers, only 0.44 ~ 0.88 cn/dtex (the strength of polyether type is higher than that of polyester type). The moisture absorption range is small, generally 0.3- 1.2% (the moisture absorption rate of multifilament is slightly higher than that of monofilament). Heat tolerance varies greatly with different varieties. Most fibers will not be damaged when stored for a short time in the range of 90 ~ 150℃. The safe ironing temperature is below 150℃, which can be heated and disturbed and wet washed. It has excellent dyeing performance, can be dyed in various shades, has strong affinity for fibers, can adapt to most kinds of dyes, has good chemical resistance, is resistant to most acids, alkalis, chemicals, organic solvents, dry cleaners and bleaches, is resistant to sun and snow, but is not resistant to oxides, and is easy to make fibers yellow and reduce strength.
Generally, spandex is not used alone, but a small amount is mixed into the fabric. This kind of fiber has both rubber properties and fiber properties, and is often used in core-spun yarn with spandex as the core, which is called elastic core-spun yarn. The main characteristics of this kind of yarn are: first, it can obtain good hand feel and appearance, and the outer fiber is composed of natural fiber, which has good hygroscopicity; Second, only 1- 10% spandex filament can produce high-quality elastic yarn; 3. The control range of elasticity percentage is from 10% to 20%, and different elasticity values can be selected according to the product use. It is easy to spin silk with different thickness of 25 ~ 2500 denier, so it is widely used to make elastic knitted fabrics, such as socks, furniture covers, ski clothes, sportswear, medical fabrics, belts, military equipment, elastic parts of spacesuits and so on. As people put forward new requirements for fabrics, such as lightness, comfort and softness, the proportion of low denier spandex fabrics in synthetic fiber fabrics is also increasing. There are nude spandex yarns and twisted yarns formed by combining spandex with other fibers, which are mainly used in various warp-knitted and weft-knitted fabrics, woven fabrics and elastic fabrics.
User manual of spandex elastic fiber
[Chapter I]
(1) Introduction of spandex elastic fiber
Spandex, translated as "spandex", is an elastic fiber, the scientific name is polyurethane fiber, or PU for short. Chinese mainland called it.
"Spandex", with high elasticity, can be stretched 6-7 times, and can quickly recover to its original state with the disappearance of tension. Its molecular structure is chain-like, soft and malleable polyurethane, and its characteristics are enhanced by connecting with hard segments. Elastic fibers are divided into two categories: one is polyester chain; One is polyether chain. Polyester elastic fiber has strong oxidation resistance and oil resistance; Polyether elastic fiber has good mildew resistance and detergent resistance.
(B) the development of spandex
Since 1958 DuPont introduced spandex into commercial use and registered its trademark as (Lycra), the market transliteration was [Lycra], many people took "LYCRA" as the name of spandex. Since then, it has been produced all over the world, such as American rubber.
Co.), ESPA of Toyobo of Japan, DORLASTAN of Bayer of Germany and West Germany, Spanzelle of COURTAULDS of England (B.
"ESTANE" from Japan Chemical Company and "FUJIBO" from Fuji Textile Company.
(Fuji), DuPont and Toray Japan's "Toray-DuPont" (Global
Manufacturing company)
CLEARSPAN and GLOSPAN of TAE Light in Korea, ACELAN, TEXLON of TONGKOOK, TOPLON and CREORA of Xiaoxing are the largest in the world. Japan Asahi Kasei
ROIKO, and then Asahi Kasei cooperated with Formosa Plastics Group of Taiwan Province Province to start Formosa Plastics in early 1999.
Asahi Company, referred to as "FAS", is the "Mobil" of Nisshin Textile in Japan.
(Mobil Long) has also increased its production line in Taiwan Province Province to produce Donghua yarn, Taiwan Province Province has invested in SHEIFLEX from Xue Heng, Chinese mainland also has Xinxing from Yantai and Aoshen from Lianyungang, all of which are produced by the equipment and technology of Dongfang Spinning, and Guangdong Heshan spandex factory is also located at 1996. In addition, DuPont also cooperates with other factories (but DuPont is not involved in production matters) and sells them under the brand "ELASPAN". All parts of the world have invested in or increased the production of spandex, making the spandex market prosperous.
(3) production method of spandex
Polyurethane fiber overcomes the quality defects of rubber yarn such as stress, strain performance, count range and modulus, and is similar to DuPont.
Dry spinning was originally used for production. Today, there are roughly four production methods:
(1) dry spinning: a method in which a solution solidifies into filaments due to solvent volatilization under hot air flow.
Production process: solution (passing through)-spinning pump (filtering)
-drying oven (blowing hot air at 100℃ to volatilize the solution)-spinning-winding forming.
Spinning speed: from 200 to 800 m/min.
Spinning temperature: 200 ~ 230℃
Fiber size: 22.2 ~ 1244 decitex
Adoption: DuPont, Bayer and Toyo Textile.
Features: process pollution, complex process and high cost.
(2) Melt spinning: a method of heating a polymer above the melting point to become a melt and spinning it into filaments.
Production technology: solvent-free polymer polymerization-granulation-constant temperature slicing-cleaning and impurity removal-drying-dehydration-solution entering screw press mechanism-spinneret extrusion-cold box cooling-winding molding.
Spinning speed: from 600 to 1600 m/min.
Spinning temperature: 160 ~ 220℃
Fiber size: 9 ~ 1 100 decitex
Uses: Bell spinning, Bayer spinning and Nissin spinning.
Features: short process, low cost and little pollution.
(3) Wet spinning: a method in which the stock solution is solidified into filaments through secondary diffusion in a solidification bath.
Production technology: stock solution-spinning pump (filtration)-warm water from spinneret (below 90℃)-coagulation bath in regeneration tank-desolventizing-silk washing-drying-winding molding.
Rotation speed: from 50 to150m/min.
Spinning temperature: warm water below 90℃
Fiber size: 44 ~ 440 decitex
Adoption: Japanese Fuji spinning.
Features: This method has the advantages of heavy pollution, slow spinning speed and high cost.
(4) Chemical reaction method: a method in which a solution made of high polymer undergoes a chemical reaction through a chain extender and is solidified into filaments.
Production technology: solution-from spinneret to solidification solution-adding chain extender (chemical reaction)-winding forming-hardening-processing into mesh fiber.
Rotation speed: from 50 to150m/min.
Fiber size: 44 ~ 80 decitex
Adoption: Universal Picture, USA
Features: This method has high pollution and high cost.
(D) the form of spandex
There are also different brightness forms in spandex production, which usually include: (taking DuPont as an example)
Transparent (clear-
Gloss): the surface fiber is smooth, so the light is reflected as transparent, with low friction rate, poor uniformity and chromatic aberration. Suitable for producing short fiber materials, widely used in warp knitted fabrics.
Dark light: white in nature, with uneven surface fibers, large friction surface and good coloring effect, suitable for blending.
Long fiber production, used for thick roots, bust and other products and accessories
Glossy: titanium dioxide and anti-slip agent are added, which has strong chemical resistance and is widely used in swimsuits.
Because it has anti-chlorine function.
Sub-gloss: between the original white and translucent, it is dumb white and suitable for knitting.
Spandex has different uses and various product forms, which are mainly divided into bare yarn, core-spun yarn, covered yarn or twisted yarn.
Each different combination corresponds to a different purpose.
Bare yarn:
For 100% spandex yarn, bare yarn is generally not directly used for fabric, and it is mostly made of hand-made material, which requires special equipment for production. Knitwear is the most commonly used, such as swimsuit and sportswear, generally 22-78Dtex.
covering yarn
The yarn spun with bare yarn as the core and other materials as the skin is called CSY for short. If the stretched bare yarn is inserted into the ring spinning frame with cotton core, the elongation of the bare yarn of core-spun yarn must be properly adjusted to restrain its expansion rate to 2 ~ 3 times. Nowadays, core-spun yarn can be divided into hard core yarn and soft core yarn. The competitive raw materials of core-spun yarn are cotton, polyester and acrylic fiber. Widely used in fabrics, knitwear, bandages, socks, underwear, jeans, generally 22-235Dtex.
Count and blending ratio of common core-spun yarn (%);
60' s cotton bales 22dtex = 92% cotton spandex 8%
In 1980s, cotton bales were 22dtex = 90% cotton spandex 10%.
55s cotton bale 33dtex = cotton 9 1% spandex 9%
In 1960s, cotton bales were 33dtex = 90% cotton spandex 10%.
30 seconds cotton bale 44 decitex = cotton 92% spandex 8%
40s cotton bale 44 dtex = 90% cotton spandex 10%
50s cotton bale 44dtex = 87% cotton spandex 13%.
12s cotton bale 78 dtex = cotton 96% spandex 4%
16s cotton bale 78 dtex = 95% cotton and 5% spandex.
78 decitex for 20 seconds cotton bale = 93% cotton and 7% spandex.
30 seconds cotton bale 78 dtex = 90% cotton spandex 10%
40s cotton bale 78 dtex = cotton 87% spandex 13%
50s cotton bale 78 dtex = 84% cotton spandex 16%
20s bales 122dtex = 93% cotton and 7% spandex.
36s cotton bale 122dtex = cotton 9 1% spandex 9%
8s bales 155 decitex = 95% cotton and 5% spandex.
20s cotton bales 155 decitex = cotton 88% spandex 12%
36s cotton bale 155 dtex = cotton 79% spandex 2 1%
40s cotton bales 155 decitex = cotton 77% spandex 23%
Covered yarn or twisted yarn: When weaving elastic fabrics with nylon and polyester fibers of equal length, the covered yarn is often twisted with the opponent yarn. Usually in order to improve the coverage of spandex, two or three hand yarns can be twisted. The yarn that the other side has a layer of coating is called single coated yarn (SCY), and the double coated yarn is called double coated yarn (DCY), which is roughly called (FTY), mainly using 44.
Mixing ratio of common coated yarn and twisted yarn (%):
56 decitex nylon bag 78 decitex = nylon 88% spandex 12%
78 decitex nylon bag 78 decitex = nylon 92% spandex 8%
78 dtex nylon bag 33dtex = nylon 88% spandex 12%
78 dtex nylon bag 44 dtex = nylon 63% spandex 14%
78 decitex nylon bag 78 decitex = nylon 78% spandex 22%
83dtex nylon bag 22dtex = nylon 92% spandex 8%
83dtex nylon bag 33dtex = nylon 89% spandex 1 1%
83dtex nylon bag 44dtex = nylon 86% spandex 14%
83dtex nylon bag 78dtex = nylon 78% spandex 22%
Mixing rate of special target fiber (%)
20s/2 cotton bale 44 decitex = 98% cotton and 2% spandex.
30 seconds /2 cotton bales 44 decitex = 97% cotton and 3% spandex.
40s/2 cotton bale 44 decitex = 96% cotton and 4% spandex.
20s/2 pack of 78 decitex = 96% cotton and 4% spandex.
30 seconds /2 bales of 78 decitex = 95% cotton and 5% spandex.
40s/2 cotton bale 78 dtex = cotton 93% spandex 7%
30s/2 polyester package 44dtex = 97% polyester and 3% spandex.
(e) Physical properties of elastic fibers
Spandex is generally composed of multiple filaments, generally 10d/ root, and now there are 15d/ root, or even 20D/ root. The less the theoretical number, the better the uniformity. DMAC, the production solution of dry spinning, is harmful to human liver because there is less chance of morphological overlap, and the content of 10d/ root is generally controlled at 0.5mg/ root. When producing spandex, special attention should be paid to the winding tension, the number of counts on the cylinder, the breaking strength, the elongation at break, the forming degree, the oil sticking rate and the elastic recovery rate. These problems directly affect knitting, especially when knitting one-sided cloth.
(1) packaging tension (packaging draft
%): The winding tension of elastic fiber is very important, and it should be uniform from the inside out. If the tension is uneven, it will directly affect the weaving effect. The best winding Zhang Liwei is 8%- 12%. The tension error of each spool should not exceed 3%.
(2) The number of branches on the cylinder (DTEX)
Bobbin): The count on the reel is controlled by the winding tension. For example, the winding Zhang Liwei of 44dtex is 10%, that is, the actual count on the reel is 40dtex, that is, it is thinned 10%. At present, some spandex manufacturers believe that spandex with high winding tension will undoubtedly have longer length, more weaving length and lighter fabric under the same weight of spandex brands, so it is necessary to pay attention to the requirements of their own products.
(3) Breaking strength (BERAKING
Toughness): Generally, the strength performance of each different brand or series of spandex is different. The test method can be tested with a powerful machine in a conditional environment, 50mm, 100%(SS 100), 200%(SS200) and 300%(SS300), five times each.
(4) Fracture elongation (BERAKING
Elongation): When measuring the breaking strength, you can measure the elongation at break. Generally speaking, the greater the elongation, the less the fabric content.
(5) Molding degree: Through the appearance test, if the molding is not good, each bobbin has different shapes and sizes, which are all unqualified.
(6)
Oil content: The optimum oil content of spandex is 5%(+/-2%). The more oil content or the longer the time, the oil in the outer layer will penetrate into the inner layer and accumulate at the bottom of the needle cylinder, which will affect the knitting tension and loss. The general oil component is silicone oil, which contains metal stearate ions.
(7)
Elastic recovery rate: Generally, the fiber elongation is above 100%, which is called elastic fiber. It means that the length increases under the action of tension, and then returns to the original length after release. The difference rate between the original length and the recovery length is elastic recovery rate, which is generally more than 95%.
Specific gravity: The specific gravity of spandex is 1. 10.
(9) Official moisture regain: generally 1.3(ASTM).
(10) Softening temperature: generally, it is 190 degrees Celsius /390 degrees Fahrenheit.
(1 1) melting temperature: generally 250 degrees Celsius /437 degrees Fahrenheit.
Standard method for storage and use of spandex:
Spandex should be stored in a constant temperature and humidity environment, and the temperature is between 18-20 degrees Celsius. The lower the temperature, the longer the storage period, and the relative humidity is 60%-70%. It should not be exposed to the sun, nor should it be stored with chemical products such as sulfur dioxide and nitrogen oxides, resulting in its decomposition.
Storage life: at the end of 20D(3 months), 30D(4 months), 40D-70D(6 months), 100D-280D(9 months),
It is thicker than 420D( 12 months), and the thicker the spandex, the longer the shelf life.
In the weaving process, spandex should be unpacked at least 16 hours in advance from the constant temperature warehouse to the workshop, and put in the weaving workshop for moisture regain to reduce yarn breakage in the weaving process.
(g) Simple test method for spandex:
1, boiling water shrinkage test
(1) Take four spandex samples, remove the surface layer, and then take three sections with the length of 10cm, and mark the distance with a colored pen.
(2) Put the sample in boiling water (65438 000℃) for 65438 00 minutes,
Then take it out to dry at room temperature, and measure its shrinkage length after 5 minutes.
(3) According to the difference before and after boiling water, calculate the boiling water shrinkage rate, and the standard rate is 10-15%.
Boiling water shrinkage (%)=( 10cm- test length)/10x100%
Conclusion: The boiling water shrinkage exceeds (10- 15%), which indicates that the stability of spandex is poor.
2. Elasticity test of spandex.
(1) Take four spandex samples, remove the surface layer, and then take three sections with the length of 10cm respectively, and mark the distance with a colored pen.
(2) Connect the samples end to end, put them on a single yarn strength machine, and stretch them at a speed of 50cm/ min.
(3) firstly, the sample is stretched for three times, respectively 100%, 150%, 200%, 250% and 300%,
Then the tensile stress (cn) and elastic recovery rate are calculated for the fourth time.
Elastic recovery rate% =( 10cm- test length)/10 X 100%.
Conclusion: Different products require different elasticity of spandex. Some products require low elongation, high elasticity or high elongation, low elasticity or low elongation, low elasticity or high elongation and high elasticity.
Therefore, different kinds of fabrics should choose different suitable spandex. Compared with other brands, the compliance rate is 300%, and the quality of spandex used by enterprises is consistent.
(h) Various functional categories of elastic fibers:
Each brand of conventional spandex has different extensibility and strength, so we can choose suitable spandex to produce suitable elastic fabrics according to the requirements of the final product. In addition to the conventional spandex, various brands have recently developed some spandex products with special functions, which gives users more choices and is more suitable for the requirements of the final product. For example: (1)
Special elasticity and comfort function: LYCAR-SOFT produced by DuPont is the first product, which is characterized by the fact that the fabric will not feel tight when worn. Dupont also has strict requirements for Lycra-soft fabrics, and only qualified fabrics can be listed. Generally, the fabric will be tensile tested on INSTRON tensile machine first, and the eligibility criteria are as follows:
Warp-knitted fabric: minimum 70% working recovery slope is 5.0.
Or less.
(b) Weft knitted fabric: minimum 70% working recovery slope is
10.0 or less
Asahi Kasei's ROICA HS system also has proximity function.
(2) Special chlorine resistance: ROICA-SP from Asahi Kasei, T- 162 from DuPont and ESPA from Toyo Textile.
T- 365, Mobil -k of Nisshin Insurance, Cleola of Xiaoxing.
C-200 and so on
(3) Special high temperature resistance: suitable for chemical fibers, such as T- 169 of DuPont and ESPA of Toyo Textile.
Nisshin's T-765, Mobil -P, and Xiaoxing's CREORA C-300, etc.
(4) Special low-temperature function: it is suitable for hand-feel materials that are not resistant to high temperature, such as wool and nylon, or yarn-dyed fabrics that are afraid of high-temperature discoloration or bleaching and yellowing, such as ESPA-M of Dongyang Spinning, Mobil -R of Nissin Spinning and U-shape of Fuji Spinning.
(5) Special moisture absorption: RIOCA-BZ from Asahi Kasei, EM from Fuji Bao, etc.
(6) Durability and wear resistance: for example, ESPA T-70 of Dongyang Textile and E-type of Fuji Textile.
(7) Other special functions: such as KA, UA, EF far infrared ray, etc.