Spandex or elastane is a synthetic fiber known for its exceptional elasticity. It is strong, but less durable than its major non-synthetic competitor, natural latex. It is a polyurethane-polyurea copolymer that was invented in 1959 by chemists C. L. Sandquist and Joseph Shivers at DuPont's Benger Laboratory in Waynesboro, Virginia. When first introduced, it revolutionized many areas of the clothing industry.
The name "spandex" is an anagram of the word "expands". It is the preferred name in North America; in continental Europe it is referred to by variants of "elastane", i.e. elasthanne (France), elastan (Germany), elastano (Spain and Portugal), elastam (Italy) and Elasthaan (Netherlands), and is known in the UK, Ireland, Brazil, Argentina, Australia, New Zealand and Israel primarily as Lycra. Brand names for spandex include Lycra (made by Koch subsidiary Invista, previously a part of DuPont), Elaspan (also Invista), Acepora (Taekwang), Creora (Hyosung), INVIYA (Indorama Corporation), ROICA and Dorlastan (Asahi Kasei), Linel (Fillattice), and ESPA (Toyobo).
Spandex fibers production
Spandex fibers are produced in four different ways: melt extrusion, reaction spinning, solution dry spinning, and solution wet spinning. All of these methods include the initial step of reacting monomers to produce a prepolymer. Once the prepolymer is formed, it is reacted further in various ways and drawn out to make the fibers. The solution dry spinning method is used to produce over 94.5% of the world's spandex fibers.
Solution dry spinning
Step 1: The first step is to produce the prepolymer. This is done by mixing a macroglycol with a diisocyanate monomer. The two compounds are mixed in a reaction vessel to produce a prepolymer. A typical ratio of glycol to diisocyanate is 1:2.
Step 2: The prepolymer is further reacted with an equal amount of diamine. This reaction is known as chain extension reaction. The resulting solution is diluted with a solvent (DMAc) to produce the spinning solution. The solvent helps make the solution thinner and more easily handled, and then it can be pumped into the fibre production cell.
Step 3: The spinning solution is pumped into a cylindrical spinning cell where it is cured and converted into fibres. In this cell, the polymer solution is forced through a metal plate called a spinneret. 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. This process causes the liquid polymer to react chemically and form solid strands.
Step 4: As the fibres exit the cell, an amount of solid strands are bundled together to produce the desired thickness. Each fibre of spandex is made up of many smaller individual fibres that adhere to one another due to the natural stickiness of their surface.
Step 5: The resulting fibres are then treated with a finishing agent which can be magnesium stearate or another polymer. This treatment prevents the fibres' sticking together and aids in textile manufacture. The fibres are then transferred through a series of rollers onto a spool.
Major spandex fibre uses
Because of its elasticity and strength (resistance to 600% elongation before rupture), spandex has been incorporated into a wide range of garments, especially in skin-tight garments. A benefit of spandex is its significant strength and elasticity and its ability to return to the original shape after stretching and faster drying than ordinary fabrics.
The types of garments which incorporate spandex include:
- Apparel and clothing articles where stretch is desired, generally for comfort and fit, such as:
- athletic, aerobic, and exercise apparel
- bra straps and side panels
- competitive swimwear
- cycling jerseys and shorts
- dance belts worn by male ballet dancers and others
- netball bodysuits
- orthopaedic braces
- rowing unisuits
- cross country race suits
- ski pants
- skinny jeans
- socks and tights
- swimsuits/bathing suits
- Compression garments such as:
- foundation garments
- motion capture suits
- Shaped garments such as:
- Home furnishings, such as microbead pillows
For clothing, spandex is usually mixed with cotton or polyester, and accounts for a small percentage of the final fabric, which therefore retains most of the look and feel of the other fibers. In North America it is rare in men's clothing, but prevalent in women's. An estimated 80% of clothing sold in the United States contained spandex in 2010.
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