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Spandex
- May 15, 2018 -

basic introduction



Spandex (spandex)



Spandex is an abbreviation of polyurethane fiber and is a synthetic fiber consisting of a polyurethane containing more than 85% of its components. Trade names include Lycra (Lycra, United States, United Kingdom, Netherlands, Canada, Brazil), Nylon (Neolon, Japan), Dorlastan (Dorlastan, Germany), etc. Firstly, it was successfully studied by Bayer Company in Germany in 1937. DuPont began industrial production in 1959 and now sells its spandex industry to Koch Industries, with a total capacity of about 100,000 tons. At present, the total global spandex production capacity is about 600,000 tons, while the production capacity of spandex production of Korea Hyosung Company is close to 120,000 tons, making it the world's first. China's first spandex company is Yantai Spandex Factory and began production in 1989. The current production capacity in mainland China is about 350,000 tons, which is the largest spandex producer in the world.



There are two varieties of spandex, one is a mosaic copolymer of aromatic diisocyanate and hydroxyl-containing polyester segments (referred to as polyester spandex), and the other is a combination of aromatic diisocyanate and hydroxyl-containing polyether segments. Copolymer (polyether spandex). Spandex fibers, elastic polyolefin fibers and elastic composite fibers are collectively referred to as elastic fibers.



Physical characteristics



Synthetic fiber with high elongation at break (above 400%), low modulus and high elastic recovery. Multi-block polyurethane fibers in Chinese trade names. Also known as elastic fiber. Spandex has high extensibility (500% to 700%), low elastic modulus (200% elongation, 0.04 to 0.12 g/denier), and high elastic recovery (200% elongation, 95% to 99%). In addition to the higher strength, other physical and mechanical properties are very similar to natural latex filaments. It is more resistant to chemical degradation than latex filaments and has moderate thermal stability with a softening temperature above about 200°C. Most dyes and finishing agents for synthetic fibers and natural fibers are also suitable for the dyeing and finishing of spandex. Spandex is resistant to sweat, seawater, and a variety of dry cleaners and most sunscreens. Exposure to sunlight or chlorine bleach may also fade, but the degree of discoloration varies with the type of spandex.



Spandex fiber has such a high elasticity because its polymer chain is composed of a low-melting, amorphous "soft" segment as a parent and a high-melting, crystalline "hard" segment embedded therein. Due to the certain cross-linking between the molecular chains of the soft segment, a certain network structure is formed. Since the interaction force between the molecular chains is small, it can flex freely, resulting in a large elongation performance. The binding force of the rigid chain molecular chain is relatively large, and the molecular chain does not extend without limitation, resulting in high resilience. Most of the cross-sections of the yamlon filaments are dog-bone-shaped and some filaments have a smooth or serrated surface. The breaking strength is the lowest among all textile fibers, only 0.44 to 0.88 CN/dtex (polyether type is stronger than polyester type). The moisture absorption range is small, generally 0.3-1.2% (the multifilament moisture absorption rate is slightly higher than the monofilament). The heat resistance varies greatly depending on the variety. Most fibers are stored for a short period of time in the range of 90 to 150°C. Fibers are not damaged. The safe ironing temperature is 150°C or less, which can interfere with heating and wet washing. Dyeing performance is excellent, can be dyed into a variety of color, dye-fiber affinity, can adapt to the vast majority of varieties of dyes, and has good chemical resistance, resistance to most of the acid and alkali, chemicals, organic solvents, Dry cleaners and bleaches, as well as sun and snow, but not resistant to oxides, tend to yellow and weaken fibers.



Spandex is generally not used alone, but is incorporated into the fabric in small amounts. This kind of fiber has both rubber properties and fiber properties. Most of them are used as core-spun yarns with spandex as the core yarn. They are called elastic core-spun yarns. The main characteristics of these yarns are that they have good feel and appearance. The external fiber composed of natural fibers has good hygroscopicity; second, only 1-10% of spandex filaments can be used to produce high-quality stretch yarns; thirdly, the percentage of elasticity is controlled from 10% to 20% and can be used according to the purpose of the product. , Select different elasticity values. It is easy to spin 25~2500 denier yarns with different thicknesses, so it is widely used to make elastic braids, such as socks, furniture covers, ski clothes, 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, and soft texture, the proportion of low-denier spandex fabrics in synthetic fabrics is also increasing. It is also used for twisted spandex yarn and spandex combined with other fibers. It is mainly used for warp knitting, weft knitting, woven fabric and elastic cloth.



Spandex Elastic Fiber Instruction Manual



[Chapter One]



Introduction to Spandex Elastic Fiber



Spandex's name is Spandex. It is a kind of elastic fiber, and its name is Polyurethane, PU. Chinese mainland



"Spandex", which is highly elastic, can stretch 6 to 7 times, but can quickly return to its original state with the disappearance of tension. Its molecular structure is a chain-like, soft and extensible polyurethane. The ester enhances its properties by linking it with hard segments. Elastic fibers are divided into two categories: one is a polyester chain; the other is a polyether chain. Polyester elastic fibers have strong anti-oxidation and oil resistance; polyether type elastic fibers have mildew resistance and anti-detergent.



Spandex development



Since DUPONT introduced the Spandex into commercial use in 1958 with a registered trademark of (LYCRA) and the market transliteration of [Lycra], many people have used "Lycra" as the name of Spandex. Since then, it has been produced all over the world, such as U.S. RUBBER



"VYRENE" of CO.), "ESPA" of TOYOBO of Japan, "DORLASTAN" of Bayer AG (BAYER, AG, W.GERMANY), "COURTAULDS" of UK COURTAULDS, "SPANZELLE" of UK, (BFGOODRICH



"ESTANE" of CHEMICAL CO., LTD), "FUJIBO" of Fujifilm, Japan



(Fujiba), DUPONT and TORAY-DUPONT, Japan (GLOBE)



MANUFACTURING CO.)



"CLEARSPAN" and "GLOSPAN", "ACELAN" of Korea TAE-KWANG, "TEXLON" of TONGKOOK, "TOPLON" of "HYOSUNG" and "CREORA" are the largest in the world. Asahi Kasei



"ROICA" (罗依可), after which Asahi Kasei cooperated with Taiwan Formosa Plastics Group to start "FORMOSA" in early 1999.



ASAHI "Company", "FAS" for short, "MOBILON" of Nisshinbo, Japan



(Mobiron) also added TOWNSPAN Donghuasi in Taiwan, while Taiwan itself invests in Xuehengxing’s “SHEIFLEX” (Snowy Silk), and in mainland China, Yantai’s “Newcastle” and Lianyungang’s "Ao Shen" was produced by "TOYOBO" Toyobo Equipment and Technology, and the Guangdong Heshan Spandex Factory was put into operation in 1996. Fujian Changle, Nantong Haimen, Shandong Zibo also started production of spandex, and China DUPONT cooperates with Huayuan in Shanghai. , And Zhejiang Huafeng "Thousands of years" brand spandex was put into production in 2000. In addition, DUPONT also cooperates with other factories (but DUPONT does not participate in production issues) and sells it under the "ELASPAN" brand. The production of spandex has been invested or expanded worldwide, making the elastic fiber market prosperous.



Spandex Production Method



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



The first use of dry spinning production, to date, there are roughly four production methods:



(1) DRY SPINNING: A method in which a solution is solidified into a filament by volatilization of a solvent under a hot gas flow.



Production process: solution (after)----spinning pump (filter)



----Drying box (100°C hot air blows to make the solution evaporate)----spinning----winding forming



Spinning speed: from 200 to 800 M/min



Spinning temperature: 200 ~ 230 °C



Fiber denier: 22.2 to 1244dtex



Adopted: DUPONT, Bayer, Toyobo



Characteristics: Large process pollution, complicated process, high cost.



(2) Melt-spinning (MELT-SPINNING): A method in which a polymer is heated to a melting point or higher and becomes a melted filament.



Production process: Polymers are polymerized in a solvent-free manner--Pelletizing----Cut at constant temperature----Cleaning and impurity removal ----Drying----Dehydration----Enter the screw press Made into a solution ---- spinneret extrusion ---- through cold box cooling ---- coiling.



Spinning speed: from 600 to 1600 M/min



Spinning temperature: 160~220°C



Fiber denier:9~1100dtex



Use: Bell spinning, Bayer, Nisshinbo



Features: short process, low cost, low pollution



(3) WET-SPINNING: The method of solidifying filaments by double diffusion in the coagulation bath.



Production process: raw liquid - spinning pump (filtration) --- from the spinneret into the warm water (below 90 °C) --- regeneration bath coagulation bath --- remove solvent --- filament Washing ---- Drying ---- Winding.



Spinning speed: from 50 to 150 M/min



Spinning temperature: below 90 °C warm water



Fiber denier:44~440dtex



Adopted by: Japan Fuji spinning



Characteristics: This method produces large pollution, slow spinning speed and high cost.



(4) Chemical reaction method: A method in which a polymer is made into a solution and subjected to a chemical reaction by a chain extender to be solidified into a filament.



Production process: solution ---- through the spinneret to the coagulation liquid --- add chain extender (chemical reaction) ---- roll forming --- hardening --- processing into a mesh fiber.



Spinning speed: from 50 to 150 M/min



Fiber denier: 44~80dtex



Adopted by: US Global



Characteristics: This method produces large pollution and high costs.



The shape of Spandex



Spandex production also has different brightness patterns, usually: (Using 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 strip is poor, and the coloring is also poor, and it is suitable for the production of staple fiber materials.



DULL-LUSTER: This is white, the surface fiber is uneven, the friction surface is large, and the color effect is good.



Long fiber production, coarse branching, such as bust products and accessories used more.



BRIGHT-LUSTER: Titanium dioxide and anti-slip agent are added inside, and it is more resistant to chemical agents.



Because of the anti-chlorine function.



Matte color (MATT-LUSTER): between the white and translucent, matte white, suitable for knitting.



Spandex is used in a variety of applications and has a variety of product forms, which can be divided into three main types: bare yarns, core-spun yarns, covered or twisted yarns.



Each different combination corresponds to different uses.



Bare yarn:



For 100% spandex yarn, bare yarn is not generally used directly on fabrics. Most of them are produced together with the opponent's materials and must be produced using special equipment. Knitwear is the most commonly used, such as swimwear, sportswear, etc., generally based on 22-78Dtex.



Core spun yarn



The yarn is used as the core, and other materials are yarns spun from the outer skin, abbreviated as CSY. For example, a cotton core is generally inserted into the spinning yarn of the ring yarn spinning machine, and the bare yarn of the covering core yarn must be properly adjusted, and its stretching rate is limited to 2 to 3 times. Core yarns are divided into hard core yarns and soft core yarns. The opponent core yarns are cotton, polyester, and clear. Is widely used in fabrics, knitwear, bandages, socks, underwear, jeans, generally based on 22-235Dtex.



General core yarn count and mix rate (%):



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



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



55s bale 33dtex = cotton 91% spandex 9%



60s bale 33dtex = cotton 90% spandex 10%



30s bale 44dtex = cotton 92% spandex 8%



40s bale 44dtex = cotton 90% spandex 10%



50s bale 44dtex = cotton 87% spandex 13%



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



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



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



30s bales 78dtex = cotton 90% spandex 10%



40s cotton bale 78dtex = cotton 87% spandex 13%



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



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



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



8s bale 155dtex = cotton 95% spandex 5%



20s bale 155dtex = cotton 88% spandex 12%



36s bale 155dtex = cotton 79% spandex 21%



40s cotton bale 155dtex = cotton 77% spandex 23%



Wrapping or twisting yarns: Long fibers such as nylon and polyester, and woven elastic fabrics are mostly made of twisted yarns covered with twisted yarns and twisted yarns, usually in order to increase the coated degree of spandex. Two or three yarns can also be combined, the opponent yarn package is called a single coated yarn (SCY), double package called double coated yarn (DCY), relatively thick (FTY), mainly used