Today fashion designers are much conscious than ever and have up-to date information about the latest fashion trends . The present –day consumer demands fashionable garments ,which offer comfort and style , stretch and flexibility , freedom and figure enhancement ,as he takes it as the tool of expressing his personality .As far as comfort is concerned ,polyester/cotton blends are more popular than pure polyester . All cotton garments may be comfortable but have wrinkle problems . It is here Spandex comes to our help in offering wrinkle resistance and garment integrity while offering extra comfort . The wearer of Spandex –containing garment feels less fatigued and muscle strain than the one wearing garments without Spandex . This value of Spandex is well recognized by the fabric and apparel manufacturers as well as the consumers .
The development of spandex was started during World War II. At this time, chemists took on the challenge of developing synthetic replacements for rubber. Two primary motivating factors prompted their research. First, the war effort required most of the available rubber for building equipment. Second, the price of rubber was unstable and it fluctuated frequently. Developing an alternative to rubber could solve both of these problems. At first, their goal was to develop a durable elastic strand based on synthetic polymers . In 1940, the first polyurethane elastomers were produced. These polymers produced millable gums, which were an adequate alternative to rubber. Around the same time, scientists at Du Pont produced the first nylon polymers. These early nylon polymers were stiff and rigid, so efforts were begun to make them more elastic. When scientists found that other polyurethanes could be made into fine threads, they decided that these materials might be useful in making more stretchable nylons or in making lightweight garments.
The first spandex fibers were produced on an experimental level by one of the early pioneers in polymer chemistry, Farbenfabriken Bayer. He earned a German patent for his synthesis in 1952. The final development of the fibers were worked out independently by scientists at Du Pont and the U.S. Rubber Company. Du Pont used the brand name Lycra and began full scale manufacture in 1962. They are currently the world leader in the production of spandex fibers. The first spandex fibers were produced on an experimental level by one of the early pioneers in polymer chemistry, Farbenfabriken Bayer. He earned a German patent for his synthesis in 1952. The final development of the fibers were worked out independently by scientists at Du Pont and the U.S. Rubber Company. Du Pont used the brand name Lycra and began full scale manufacture in 1962. They are currently the world leader in the production of spandex fibers.
Spandex, Lycra or elastane, is a synthetic fibe known for its exceptional elasticity. It is one and the same .It is stronger and more durable than rubber, its major non-synthetic competitor. It is a polyurethane-polyurea copolymer that was invented in 1959 by chemist Joseph Shivers at DuPont’s Benger Laboratory in Waynesboro, Virginia. The material was patented by the Spanjian brothers—Robert and Richard—and was further used in their company, Spanjian Sportwear. When first introduced, it revolutionized many areas of the clothing industry.The product name “Spandex” was given to the Spanjian family after DuPont recognized their contributions. “Spandex” is the preferred name in North America and in many European countries it is referred to as “elastane”. In India it is commonly used as Lycra. A brand name associated with spandex is Lycra (owned by Invista). Other spandex trademarks include Elaspan (also Invista’s), creora (Hyosung, ROICA & Dorlastan (Asahi Kasei), Linel (Fillattice), and ESPA (Toyobo).
Materials Used for Spandex Fibers
Many raw materials are used to make the unique stretchable spandex fibers. They include prepolymers which produce the backbone of the fiber, stabilizers which protect the integrity of the polymer, and textile colorants to give attractive shades to the fibers and the spandex fabrics. Two kinds of prepolymers are reacted to produce the spandex fiber polymer back-bone- the flexible macroglycol and the rigid diisocyanate. Macro-glycol can be anything from among polyester, polyether, polycarbonate, polycaprolactone or some combination of these. These are long and flexible chain polymers having hydroxyl groups (-OH) on both ends, responsible for the stretching characteristic of spandex. The polymeric diisocyanate is a shorter and rigid chain polymer, having an isocyanate (-NCO) group on both ends. This molecule provides strength to the spandex fibers. Catalyst such as diazobicyclo octane is used to initiate reaction between the two types of prepolymers. Other low molecular weight amines are used to control the molecular weight of the fibers.
Apart from the basic prepolymers, catalysts etc. stabilizers, such as antioxidants, are added to protect the fibers from damaging sources like heat, light, atmospheric contaminants, and chlorine. Ultraviolet (UV) screeners such as hydroxybenzotriazoles are added to protect it against light degradation. Other stabilizers such as for preventing discoloration caused by atmospheric pollutants may also be used. As spandex is often used for making swim wear, antimildew additives are also added to it. Stabilizers added to the spandex fibers, are resistant to solvent exposure as this could have a damaging effect on the fiber. Dispersed and acid dyes are typically used for giving color to spandex fibers. However, special dyeing methods are adopted if the spandex fibers are interwoven with other fibers such as nylon fiber or polyester fiber.
A variety of raw materials are used to produce stretchable spandex fibers. This includes prepolymers which produce the backbone of the fiber, stabilizers which protect the integrity of the polymer, and colorants.
Two types of prepolymers are reacted to produce the spandex fiber polymer back-bone. One is a flexible macroglycol while the other is a stiff diisocyanate. The macro-glycol can be a polyester, polyether, polycarbonate, polycaprolactone or some combination of these. These are long chain polymers, which have hydroxyl groups (-OH) on both ends. The important feature of these molecules is that they are long and flexible. This part of the spandex fiber is responsible for its stretching characteristic. The other prepolymer used to produce spandex is a polymeric diisocyanate. This is a shorter chain polymer, which has an isocyanate (-NCO) group on both ends. The principal characteristic of this molecule is its rigidity. In the fiber, this molecule provides strength.
When the two types of prepolymers are mixed together, they interact to form the spandex fibers. In this reaction, the hydroxyl groups (-OH) on the macroglycols react with the isocyanates. Each molecule gets added on to the end of another molecule, and a long chain polymer is formed. This is known as a step-growth or addition polymerization. To initiate this reaction, a catalyst such as diazobicyclo[2.2.2]octane must be used. Other low molecular weight amines are added to control the molecular weight of the fibers.
Spandex fibers are vulnerable to damage from a variety of sources including heat, light atmospheric contaminants, and chlorine. For this reason, stabilizers are added to protect the fibers. Antioxidants are one type of stabilizer.
Various antioxidants are added to the fibers, including monomeric and polymeric hindered phenols. To protect against light degradation, ultraviolet (UV) screeners such as hydroxybenzotriazoles are added. Compounds which inhibit fiber discoloration caused by atmospheric pollutants are another type of stabilizer added. These are typically compounds with tertiary amine functionality, which can interact with the oxides of nitrogen in air pollution. Since spandex is often used for swimwear, antimildew additives must also be added. All of the stabilizers that are added to the spandex fibers are designed to be resistant to solvent exposure since this could have a damaging effect on the fiber.
When they are first produced, spandex fibers are white. Therefore, colorants are added to improve their aesthetic appearance. Dispersed and acid dyes are typically used. If the spandex fibers are interwoven with other fibers such as nylon or polyester, special dying methods are required
Spandex fibers are produced in four different ways including melt extrusion, reaction spinning, solution dry spinning, and solution wet spinning. Each of these methods involve the initial step of reacting monomers to produce a prepolymer. Then the prepolymer is reacted further, in various ways, and drawn out to produce a long fiber. Since solution dry spinning is used to produce over 90% of the world’s spandex fibers, it is described.
- The first step in the production of spandex is the production of the prepolymer. This is done by mixing a macroglycol with a diisocyanate monomer. The compounds are mixed in a reaction vessel and under the right conditions they react to form a prepolymer. Since the ratio of the component materials produces fibers with varying characteristics, it is strictly controlled. A typical ratio of glycol to diisocyanate may be 1:2.
- In dry spinning fiber production, the prepolymer is further reacted with an equal amount of diamine. This is known as a chain extension reaction. The resulting solution is diluted with a solvent to produce the spinning solution. The solvent helps make the solution thinner and more easily handled. It can then be pumped into the fiber production cell.
Producing the fibers
- The spinning solution is pumped into a cylindrical spinning cell where it is cured and converted into fibers. In this cell, the polymer solution is forced through a metal plate, called a spinneret, which has small holes throughout. This causes the solution to be aligned in strands of liquid polymer. As the strands pass through the cell, they are heated in the presence of a nitrogen and solvent gas. These conditions cause the liquid polymer to chemically react and form solid strands.
- As the fibers exit the cell, a specific amount of the solid strands are bundled together to produce the desired thickness. This is done with a compressed air device that twists the fibers together. In reality, each fiber of spandex is made up of many smaller individual fibers that adhere to one another due to the natural stickiness of their surface.
- The fibers are then treated with a finishing agent. This may be magnesium stearate or another polymer such as poly(dimethyl-siloxane). These finishing materials prevent the fibers from sticking together and aid in textile manufacture. After this treatment, the fibers are transferred through a series of rollers onto a spool. The windup speed of the entire process can be anywhere from 300-500 mi (482.7-804.5 km) per minute depending on the thickness of the fibers.
- When the spools are filled with fiber, they are put into final packaging and shipped to textile manufacturers and other customers. Here, the fibers may be woven with other fibers such as cotton or nylon to produce the fabric that is used in clothing manufacture. This fabric can also be dyed to produce a desired color.
Properties of Spandex Fibre-
The most significant characteristic of Spandex is its stretchability. It can be stretched to a great length and then also recovers its near to original shape. It can, in fact, be stretched to almost 500% of its length. It is lightweight, soft, smooth, supple and more durable and has higher retractive ability than rubber. As such, when Spandex is used for making any clothing, it gives the best fit and comfort and also prevents bagging and sagging of the garment. It is also heat-settable which means that it facilitates transforming puckered fabrics into flat fabrics, or flat fabrics into permanent rounded shapes. Spandex fibers or fabrics can be easily dyed and they also resist damage by body oils, perspiration, lotions or detergents. These fabrics are also abrasion resistant. When Spandex is sewn, the needle causes little or no damage from “needle cutting” compared to the older types of elastic materials. The Spandex fiber diameters range from 10 denier to 2500 denier and can be found in both, clear and opaque lusters..
Lycra T-400 is a new elastic fibre based on bicomponent technology, which offers improved comfort, handle, wrinkle-resistance and easy-care properties in knitted and woven fabrics. Lycra T-400 is normally dyed under HT conditions at 130 degree centigrade. Good tone-in-tone dyeing of the single components can be achieved at this temperature, without significant loss of stretch recovery properties. DyStar recommends for Lycra T-400.
Strength: 0.55-1.0 gpd
Extension at Break: 520-610 %
Specific Gravity: 1.20-1.25
Set % at 600% stretch: 70%
Moisture Regain: 0.8-1.2
It is a thermoplastic fibres which sticks at 170 deg C and melts at 230 deg C
It has an excellent resistance to sunlight
It is resistant to insects and microorganisms.
It is resistant to common solvents such as dry cleaning solvents and saturated hydrocarbons.
It has good resistance to cold dilute Acids, Hot concentrated acids slightly yellow it.
It has a good resistance to weak and cold alkalies. It has good resistance to cosmetic oils and lotions. Chlorites and hypochlorites attack the fibre. When heated the fibres fuse and do not shrink from the flame. They burn and produce soft fluffy black ash. Spandex is a man-made elastic fibre invented and produced only by DuPont®.It’s remarkable properties of stretch and recovery enhance all fabrics and garments in which it is used, adding easy comfort and freedom of movement and improving fit and shape retention. Swimwear and lingerie owe their figure-flattering fit to Spandex. All types of hosiery are softer, smoother-fitting and more durable thanks to Spandex. In short, a little bit of Spandex makes all types of apparel fit better, feel better and look better. Spandex belongs to the generic elastane classification of man-made fibres(known as spandex in the US and Canada) and is described in technical terms as a segmented polyurethane it is composed of “soft”, or flexible, segments bonded together with “hard”, or rigid, segments. This gives the fibre it’s built-in, lasting elasticity. Spandex can be stretched four to seven times its initial length, yet springs back to it’s original length once tension is released.
While Spandex appears to be a single continuous thread, it is in reality a bundle of tiny filaments.
Spandex is never used alone; it is always combined with another fiber (or fibers), natural or man-made. Fabrics enhanced with Spandex retain the appearance of the majority fibre.
The type of fabric and it’s end use determine the amount and type of Spandex required to ensure optimum performance and aesthetics. As little as 2 percent Spandex is enough to improve a fabric’s movement, drape and shape retention, while fabrics for high-performance garments such as swimwear and active sportwear may contain as much as 20-30 percent Spandex. Weaving or knitting techniques, together with fabric type and end use, determine whether Spandex is used in a bare or covered yarn form.
The material used in the making of the Cotton-Lycra line of Snob underwear consist of:
There are many advantages of nylon/Lycra warp knitted fabrics,( Lycra 10-20% ) such as good tenacity and abrasion resistance due to the nylon, and excellent elastic recovery property due to the Lycra. The fabrics also have a fine moisture releasing, soft hand-feeling. Moreover, clothings, which are sewed with this kind of fabrics give people a feeling of pressure-free comfort, and help to build a perfect figure. The fabric selected is the nylon and Lycra blend. The dyestuff used for dyeing is acid dyestuff and the dyeing method is one-bath-two-section.
USES OF SPANDEX FIBRE-
Spandex is used in a variety of different clothing types. Since it is lightweight and does not restrict movement, it is most often used in athletic wear. This includes such garments as swimsuits, bicycle pants, and exercise wear. The form-fitting properties of spandex makes it a good for use in under-garments. Hence, it is used in waist bands, support hose, bras, and briefs. Spandex is a synthetic fiber that has an exceptional characteristic of elasticity due to which it is also known as elastane. It is lightweight, soft, strong and very stretchable. In fact, spandex fiber was developed as an alternative to rubber but has a better quality than it. The name Lycra has also come to be a synonymous of spandex. However, Lycra is the trademark brand but it has become so popular that all the varieties of spandex are popularly referred to as Lycra. Due to its durability and stretchability, spandex is mostly used to make sports wear and work wear, specially for factory workers. It wears like a second skin and for risk involved jobs like that of machine operators, Lycra clothing is like a boon.
Spandex Fiber is mainly used to make such garments that require great comfort and fit. As such, they find applications in manufacturing of hosiery, swimsuits, aerobic or exercise wear, netball body suits ,ski pants, disco jeans , skinny jeans , belts, underwear ,zentai, golf jackets, disposable diaper, gloves ,slacks , hosiery, leggings,socks,diapers , waist bands, bra straps and bra side panels etc. They are even great for making shaped garments like bra cups. Spandex fabrics are also used to make compression garments, such as surgical hose, support hose, bicycle pants, foundation garments,dance belts worn by male ballet dancers and others ,wrestling singlet ,rowing unisuit , motion capture suits shaped garments such as bra cups etc. Home furnishings, such as microbead pillows .
In clothing it usually appears as a small percentage of total material. In North America it is rare in men’s clothing, but prevalent in women’s. It is used more often in women’s as their clothes are usually more form-fitting. It is usually mixed with a greater percentage of one other textile such as cotton or polyester. This reduces the reflection of light to hardly noticeable levels.
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