Warp knitting uses multiple yarns to form loops in sequence along the longitudinal direction (warp direction) of the cloth surface

Spandex fiber is the abbreviation of polyurethane fiber, and the product name is Lake Lycra (USA, UK, Netherlands, Canada, Brazil), Neolon (Japan), Dorlastan (Germany), etc. It was first successfully researched by the German Bayer Company in 1937, and the American DuPont Company began industrial production in 1959. At present, there are nearly 40 factories and seven lines of production, with a total annual output of about 100,000 tons. my country's existing production capacity is about 10,000 tons. Spandex is a synthetic fiber composed of more than 85% polyurethane.

There are two varieties of spandex fiber. One is a mosaic polymer (referred to as polyester spandex) composed of aromatic diisomerase and polyester segments containing hydroxyl groups. The other is a polymer inlaid with aromatic diisocyanate and polyether segments containing hydroxyl groups (referred to as polyether spandex). Spandex fiber, elastic polyolefin fiber and elastic composite fiber are collectively called elastic fiber.

Synthetic fiber with high elongation at break (more than 400%), low modulus and high elastic recovery rate. Chinese trade name for multi-segmented polyurethane fiber. Also known as elastic fiber. Spandex has high elongation (500% ~ 700%), low elastic modulus (200% elongation, 0.04 ~ 0.12 g/den) and high elastic recovery rate (200% elongation, 95% ~ 99%). In addition to its greater strength, other physical and mechanical properties are very similar to natural latex silk. It is more resistant to chemical degradation than latex silk, has moderate thermal stability, and has a softening temperature above 200°C. Most dyes and finishes used for synthetic and natural fibers are also suitable for dyeing and finishing spandex. Spandex is resistant to sweat, sea water, various dry cleaning agents and most sunscreen oils. It can also fade with long-term exposure to sunlight or chlorine bleach, but the degree of fading varies greatly depending on the type of spandex.

The reason why spandex fiber has such high elasticity is that its polymer chain is composed of low melting point, amorphous "soft" segments as the matrix and high melting point, crystallized "hard" segments embedded in it. Made up of chain segments. The flexible segment molecular chains are cross-linked to form a certain network structure. Due to the small interaction force between the molecular chains, they can expand and contract freely, resulting in large elongation performance. The molecular chain binding force of the rigid segment is relatively large, and the molecular chain will not extend indefinitely, resulting in high resilience. Most of the cross-sections of radon filaments are dog-bone-shaped, and some filaments have smooth or jagged surfaces. The breaking strength is the lowest among all textile fibers, only 0.44~0.88CN/dtex (polyether type has higher strength than 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). The heat resistance varies greatly depending on the variety. Most fibers will not be damaged when stored for a short period of time in the range of 90 to 150°C. The safe ironing temperature is below 150°C, and heating interference and wet cleaning are possible. It has excellent dyeing performance and can be dyed into various colors. The dye has strong affinity for fibers and can be adapted to most types of dyes. It also has good chemical resistance and is resistant to most acids, alkalis, chemicals, organic solvents, It is resistant to dry cleaning agents and bleaches, and is resistant to sunlight, wind and snow, but is not resistant to oxidants, which can easily cause the fibers to turn yellow and reduce their strength.

Spandex is generally not used alone, but is mixed into fabrics in small amounts. This kind of fiber has both rubber and fiber properties. It is mostly used in core-spun yarns with spandex as the core yarn, which is called elastic core-spun yarn. The main features of this kind of yarn are: first, it can obtain good feel and appearance; The outer fiber composed of natural fibers has good hygroscopicity; secondly, only 1-10% spandex filament can be used to produce high-quality elastic yarn; thirdly, the elasticity percentage control range is from 10% to 20%, which can be adjusted according to the use of the product. , choose different elasticity values. It is easy to spin yarns of different thicknesses from 25 to 2500 denier, so it is widely used to make elastic knitted fabrics, such as socks, furniture covers, ski suits, sportswear, medical fabrics, belts, military equipment, elastic parts of space suits, etc. . As people put forward new requirements for fabrics, such as light weight, comfortable fit, soft texture, etc., low-denier spandex fabrics account for an increasing proportion of synthetic fiber fabrics. There are also useful spandex naked yarns and twisted yarns made by combining spandex and other fibers and twisting them. They are mainly used in various warp knitting, weft knitting fabrics, woven fabrics and elastic fabrics.

Spandex (spandex) Elastic Fiber Instruction Manual

[Chapter 1]

(A) Introduction to Spandex Elastic Fiber

Spandex Translation "Spandex" is a kind of elastic fiber, scientific name is polyurethane fiber (Polyurethane), abbreviation (PU). Called "spandex" in mainland China, it is highly elastic and can be stretched 6 to 7 times, but can quickly return to its original state as the tension disappears. Its molecular structure is like a chain, Soft and stretchable polyurethane whose properties are enhanced by linking together hard segments. Elastic fibers are divided into two categories: one is polyester chain; the other is polyether chain. Polyester elastic fiber has strong resistance to oxidation and oil; polyether elastic fiber has good mildew resistance and detergent resistance.

(B) Development of Spandex

Since DUPONT introduced Spandex for commercial use in 1958 and registered the trademark (LYCRA), which is transliterated in the market as [Lycra], many people have regarded " "Lycra" as the name of Spandex. Later, it was produced all over the world, such as "VYRENE" of U.S. RUBBER CO., "ESPA" of TOYOBO of Japan, Bayer of Germany ( "DORLASTAN" from BAYER, A.G., W.GERMANY), "SPANZELLE" from COURTAULDS, U.K., "ESTANE" from (B.F.GOODRICH

CHEMICAL CO.,LTD), "FUJIBO" from Fujibo, Japan

(Fujiba), "TORAY-DUPONT" ??jointly produced by DUPONT and Japan's Toray, and "CLEARSPAN" from the United States (GLOBE

MANUFACTURING CO.)

"GLOSPAN", "ACELAN" of TAE-KWANG, "TEXLON" of TONGKOOK, "TOPLON" and "CREORA" of HYOSUNG Hyosung are the largest in the world. Japan's Asahi Kasei's "ROICA" (Roica), and then Asahi Kasei cooperated with Taiwan's Formosa Plastics Group in early 1999 to establish "FORMOSA

ASAHI" company, referred to as "FAS" , Japan's Nisshinbo's "MOBILON"

(Mobilon) has also added a production line to produce (TOWNSPAN) Donghua silk in Taiwan, and Taiwan has invested in Xue Hengxing's "SHEIFLEX" (雪飞丝), In mainland China, there are also "New Star" in Yantai and "Aoshen" in Lianyungang, both of which are produced with the equipment and technology of "TOYOBO". The Guangdong Heshan Spandex Factory also started production in 1996, and Changle, Fujian, Haimen, Nantong, Shandong Zibo also began to produce spandex, China's DUPONT cooperated with Huayuan in Shanghai, and Zhejiang Huafeng's "Millennium" brand spandex was also put into production in 2000. In addition, DUPONT also cooperates with other factories (but DUPONT is not involved in production matters) and sells it under the "ELASPAN" brand. All over the world are investing in or expanding the production of spandex, making the elastic fiber market booming.

(C) Spandex production method

Spandex fiber overcomes quality defects such as stress, strain properties, count range and moldability of rubber yarn, that year DUPONT

Dry spinning was first used for production. Today, there are roughly four production methods:

(1) Dry spinning (DRY SPINNING): The solution is heated under hot air flow due to the solvent. A method of volatilizing and solidifying into filaments.

Production process: Solution (passed)----Spinning pump (filtration)

----Drying oven (100℃ hot air blows through to volatilize the solution)-- --Spinning----Winding forming

Spinning speed: from 200 to 800M/min

Spinning temperature: from 200 to 230℃

Fiber fineness: 22.2～1244dtex

Using: DUPONT, Bayer, Toyobo

Characteristics: large process pollution, complex process and high cost.

(2) Melt spinning (MELT-SPINNING): A method in which the polymer is heated above the melting point to form a melt and form filaments.

Production process: Polymer is polymerized without solvent----granulation----slicing at constant temperature----cleaning and impurity removal----drying----dehydration- ---Enter the screw press to form a solution----Spinneret extrusion--Cooled through the cold box--Rolling and forming.

Spinning speed: from 600 to 1600M/min

Spinning temperature: from 160 to 220℃

Fiber fineness: 9 to 1100dtex

Using: Zhongfang, Bayer, Nisshinbo

Features: short process, low cost, less pollution

(3) Wet spinning (WET-SPINNING): A method in which the original solution is solidified into filaments through double diffusion in the coagulation bath.

Production process: Raw solution----Spinning pump (filtration)----Enter warm water (below 90℃) from the spinneret----Regeneration tank coagulation bath----Strip off Solvent----silk washing----drying----winding and forming.

Spinning speed: from 50 to 150M/min

Spinning temperature: warm water below 90°C

Fiber fineness: 44 to 440dtex

Adopted: Japan Fujibo

Characteristics: The production process of this method is highly polluting, the spinning speed is slow, and the cost is high.

(4) Chemical reaction method: A method in which a polymer solution is chemically reacted with a chain extender and solidified into filaments.

Production process: solution ---- through spinneret to coagulation liquid ---- add chain extender (chemical reaction) ---- winding and forming ---- hardening --- treatment into network fibers.

Spinning speed: from 50 to 150M/min

Fiber fineness: 44 to 80dtex

Adopted: American Universal

Characteristics: The production process of this method is highly polluting and costly.

(D) Forms of Spandex

Spandex production is also divided into different brightness forms, usually: (Take DUPONT as an example)

Transparent (CLEAR -

LUSTER): The surface fiber is relatively smooth, so the reflection becomes transparent, the friction rate is low, the evenness of the evenness is poor, and the coloring is also poor. It is suitable for the production of short fiber materials and is used in many warp fabrics. .

DULL-LUSTER: The original white color, the surface fibers are uneven, the friction surface is large, the coloring effect is good, and it is suitable for long-fiber production, and the roots are thick. Used mostly in bra products and accessories.

Translucent (BRIGHT-LUSTER): Added titanium dioxide and anti-slip agent, strong resistance to chemical agents, often used in swimming suits,

because of its anti-chlorine function.

Matt color (MATT- LUSTER): It is between natural white and translucent. It is matte white and suitable for knitting.

Spandex has different uses and product forms, mainly divided into three types: bare yarn, core-spun yarn, covered or twisted yarn.

Each different combination corresponds to a different purpose.

Bare yarn:

It is 100% spandex yarn. Bare yarn is generally not used directly on fabrics. Most of them are produced with the same materials as rival materials and need to be used. Special device production. Knitwear is the most commonly used, such as swimsuits, sportswear, etc., generally 22-78Dtex.

Core spun yarn

A yarn with bare yarn as the core and other materials as the outer skin, referred to as CSY.

For example, when using cotton as a core, a drafted bare yarn is usually inserted into the spinning wheel of a ring-spinning machine. The elongation of the bare yarn wrapped around the core yarn must be adjusted appropriately, and its expansion rate is suppressed to 2 to 3 times. Today, core-spun yarns are divided into hard-core yarns and soft-core yarns. The rival materials of core-spun yarns include cotton, polyester, polyester, etc. It is widely used in fabrics, knitwear, bandages, socks, underwear, and jeans, generally 22-235Dtex.

General core-spun yarn count and mixing rate (%):

60s cotton bale 22dtex = cotton 92% spandex 8%

80s cotton bale 22dtex = 90% cotton, 10% spandex

55s cotton bag 33dtex = 91% cotton, 9% spandex

60s cotton bag 33dtex = 90% cotton, 10% spandex

30s cotton bag 44dtex = 92% cotton, 8% spandex

40s cotton bag 44dtex = 90% cotton, 10% spandex

50s cotton bag 44dtex = 87% cotton, 13% spandex

12s cotton bag 78dtex = cotton 96% spandex 4%

16s cotton bag 78dtex = cotton 95% spandex 5%

20s cotton bag 78dtex = cotton 93% spandex 7 %

30s cotton bag 78dtex = 90% cotton, 10% spandex

40s cotton bag 78dtex = 87% cotton, 13% spandex

50s cotton bag 78dtex = cotton 84% spandex 16%

20s cotton bag 122dtex = cotton 93% spandex 7%

36s cotton bag 122dtex = cotton 91% spandex 9%

8s cotton Bag 155dtex = 95% cotton, 5% spandex

20s cotton bag 155dtex = 88% cotton, 12% spandex

36s cotton bag 155dtex = 79% cotton, 21% spandex

< p>40s cotton bale 155dtex = cotton 77% spandex 23%

Covered or twisted yarn: nylon, polyester and other long fibers, when weaving elastic fabrics, mostly covered yarn and twisted yarn are naked yarns It is twisted with a rival yarn. Usually, in order to improve the covering degree of spandex, two or three yarns can be twisted together with the rival yarn. The yarn wrapped with one layer is called single covered yarn (SCY), and the one with two layers is called single covered yarn (SCY). Double covered yarn (DCY), thicker name (FTY), mainly uses 44-620Dtex, and is used for underwear and underwear accessories.

Count mixing rate (%) of general covered and twisted yarns:

56dtex nylon package 78dtex = nylon 88% spandex 12%

78dtex nylon Bag 78dtex = 92% nylon, 8% spandex

78dtex nylon bag 33dtex = 88% nylon, 12% spandex

78dtex nylon bag 44dtex = 63% nylon, 14% spandex

< p>78dtex nylon bag 78dtex = nylon 78% spandex 22%

83dtex nylon bag 22dtex = nylon 92% spandex 8%

83dtex nylon bag 33dtex = nylon 89% spandex 11%< /p>

83dtex nylon bag 44dtex = 86% nylon, 14% spandex

83dtex nylon bag 78dtex = 78% nylon, 22% spandex

Special fiber mixing rate (% )

20s/2 cotton bales 44dtex = 98% cotton, 2% spandex

30s/2 cotton bales 44dtex = 97% cotton, 3% spandex

40s/ 2 cotton bales 44dtex = cotton 96% spandex 4%

20s/2 cotton bales 78dtex = cotton 96% spandex 4%

30s/2 cotton bales 78dtex = cotton 95% spandex 5 %

40s/2 cotton bag 78dtex = 93% cotton, 7% spandex

30s/2 polyester bag 44dtex = 97% polyester, 3% spandex

(E )Physical properties of Spandex

Spandex is generally composed of multiple filaments, usually 10D/filament. Now there are 15D/filament, or even 20D/filament. The smaller the theoretical number of filaments, the better the evenness of the yarn. , because the chance of overlapping forms is less, the production solution DMAC of dry spinning is harmful to the human liver. Generally, 10D/root contains 0.5mg/kg, such as 15D/root contains 0.7mg/kg, which exceeds the standard. When producing Spandex, special attention must be paid to winding tension, count on the barrel, breaking strength, breaking elongation, formability, oil adhesion, elastic recovery rate, etc. These problems directly affect knitting, especially knitting production. Pay more attention to single-sided fabrics.

(1) Packing tension (PACKAGE DRAFT

%): The winding tension on elastic fibers is very important. The tension should be kept even from the inside to the outside. If the tension is uneven, It directly affects the effect of woven cloth. The optimal rolling tension is 8%-12%. The tension error of each package cannot exceed 3%.

(2) Number of counts on the tube (DTEX ON

CHEESE): The number of counts on the tube is controlled by the rolling tension. For example: the rolling tension of 44dtex is 10%, that is The actual count on the tube is 40dtex, which is 10% thinner. Nowadays, some spandex manufacturers believe that when the weights of each brand of spandex are the same, the spandex with higher rolling tension will undoubtedly have a longer length, a longer weaving length, and a lighter fabric. You must pay attention to this point in your own products. Select according to requirements.

(3) Breaking strength (BERAKING

TENACITY): Usually different brands or different series of spandex have different strength performance. The test method can be in a conditioned environment. Take 50mm and test it with a strong machine. Test 100% (SS100), 200% (SS200), and 300% (SS300) five times each. Generally, observe the stability of the 200% (SS200) data and other data. The greater the strength. , the elongation force of the fabric is large, and the knitting speed can also be faster.

(4) BERAKING

ELONGATION: When measuring the breaking strength, the elongation at break can be measured. Generally, the greater the elongation, the less the fabric content. Some.

(5) Forming degree: Tested by appearance. If the forming is poor, the shape of each package is different, and the size is different, it will be deemed unqualified.

(6)

Oil adhesion: The best oil content of spandex is 5% (+/-2%). The more oil content or the longer the time, the more oily the outer layer will be. The inner layer is soaked and accumulated at the bottom of the tube, affecting the braiding tension and causing large losses. The general oil component is silicone oil, containing stearic acid metal ions.

(7)

Elastic recovery rate: Generally, fibers that stretch by 100% or more are called elastic fibers. They mean that the length increases under tension and returns to the original length after release. The difference between the original length and the recovery length is the elastic recovery rate, which is generally 95% or above.

(8) Specific gravity: The specific gravity of spandex is 1.10.

(9) Official moisture regain rate: generally 1.3 (ASTM).

(10) Softening temperature: generally 190 degrees Celsius/390 degrees Fahrenheit.

(11) Melting temperature: generally 250 degrees Celsius/437 degrees Fahrenheit.

(F) Standard methods for storage and use of Spandex:

Spandex should be stored in an environment with constant temperature and humidity, between 18-20 degrees Celsius. The lower the temperature, the The storage period is relatively long, and the relative humidity is 60%-70%. It should not be placed in places exposed to sunlight. It should not be stored with chemical products such as sulfur dioxide and nitrogen oxides, which may cause their decomposition.

Storage period: below 20D (3 months), 30D (4 months), 40D-70D (6 months), 100D-280D (9 months),

Thicker than 420D (12 months), the thicker the Spandex, the longer the storage period.

When Spandex is weaving, the cartons are opened at least 16 hours in advance from the constant-temperature warehouse to the workshop and placed in the weaving workshop to regain moisture to reduce yarn breakage during weaving.

(G) Simple test method for Spandex:

1. Boiling water shrinkage test

(1) Take four spandex samples, remove the surface layer, and then separate Take three paragraphs 10cm long and mark the distance with a colored pen.

(2) Put the sample into boiling water (100℃) for 10 minutes,

then take it out and hang it to dry at room temperature. After 5 minutes, measure its length after shrinkage .

(3) Calculate the boiling water shrinkage rate based on the difference before and after boiling water. The standard rate is 10-15%.

Boiling water shrinkage (%) = (10cm - test length) /10×100%

Conclusion: Boiling water shrinkage exceeds (10-15%), indicating poor stability of spandex .

2. Spandex elasticity test.

(1) Take four spandex samples, remove the surface layer, then take three sections of 10cm in length, and mark the distance with a color pen.

(2) Join the head and tail of the sample, place it on a single yarn strength machine, and stretch it at a speed of 50cm/minute.

(3) First, stretch the sample 3 times by 100%, 150%, 200%, 250%, and 300%.

Then calculate the tensile strength after the fourth time. Tensile stress (cn) and elastic recovery rate.

Elastic recovery rate %= (10cm - test length) / 10 X 100%

Conclusion: Different products have different elastic requirements for spandex, and some products require low stretch for spandex Long, high elasticity or high elongation, low elasticity or low elongation, low elasticity or high elongation, high elasticity,

Therefore, different types of fabrics require different suitable spandex. The standard rate is compared with the 300% data of other brands. The quality of the spandex used by Uibao Enterprises is consistent.

Various functional categories of (H)Spandex:

Each brand of conventional spandex has different elongation and strength. You only need to select the appropriate one according to the requirements of the final product. With spandex, suitable elastic fabrics can be produced. In addition to regular spandex, various brands have recently developed spandex products with special functions, giving users more choices and more suitable for the final product requirements.

For example: (1)

Special elastic comfort function: LYCAR-SOFT produced by DUPONT is first recommended. Its characteristic is that the fabric does not feel tight when worn, and DUPONT is also suitable for LYCRA-SOFT fabrics. There are strict requirements, and the fabric will be listed only after passing the test. Generally, the fabric is first tested on the INSTRON stretching machine for tensile and recovery rates. The qualification standards are:

(a) Warp knitted fabric: MINIMUM 70% WORK RECOVERY SLOPE OF 5.0

OR LESS

(b)Weft knitted fabric: MINIMUM 70% WORK RECOVERY SLOPE OF

10.0 OR LESS

Asahi Kasei's ROICA HS system also has similar functions.

(2) Special anti-chlorine function: such as Asahi Kasei's ROICA-SP, DUPONT's T-162, TOYOBO's ESPA

T-365, NISSHINBO's MOBILON-K, HYOSUNG's CREORA

C-200 etc.

(3) Special high temperature resistance function: suitable for chemical fibers, such as DUPONT's T-169, TOYOBO's ESPA

T-765, NISSHINBO's MOBILON-P, HYOSUNG's CREORA C-300 etc.

(4) Special low temperature function: suitable for materials that are not resistant to high temperatures, such as wool, nylon, or yarn-dyed fabrics that are afraid of high temperature discoloration or bleaching and yellowing, such as TOYOBO's ESPA-M, NISSHINBO MOBILON-R, FUJIBO U-shaped, etc.

(5) Special moisture absorption and moisture permeability functions: such as Asahi Kasei's RIOCA-BZ, FUJIBO's EM type, etc.

(6) Durable wear resistance function: such as TOYOBO's ESPA T-70, FUJIBO's E type, etc.

(7) Other special functions: such as FUJIBO's KA and UA type antibacterial and deodorant, EF type far infrared rays, etc.