Lyocell

History of Lyocell

In the early 1990s, the UK/US based textile manufacturer Courtaulds (now Acordis) developed an innovative technology for producing a biodegradable, 100% cellulose-based fibre from wood. Through this process, water consumption is strongly lowered compared with cotton and the solvent used is 99.6% recyclable.

Lenzing Fibres, another major manufacturer of rayon, has also entered the Lyocell market. This product is marketed as Lenzing Lyocell.

Lyocell was designated by BISFA (Bureau International pour la Standardisation de la Rayonne et des Fibres Synthetiques) as belonging to a new generic class, and was the first new generic fibre group to be approved by the Federal Trade Commission in 30 years.
Lyocell fibres were predicted to have a big future, and industry today has fulfilled this prediction. Garments containing Tencel are available from numerous shops in the UK and US.
The most notable example to date is Levis Engineered Jeans, which are manufactured with a mixture of 70% cotton and 30% Tencel fibre.

Chemistry and Production

The fibres are produced by a process called NMMO, where wood cellulose is dissolved directly in n-methyl-morpholine-n-oxide at high temperature and pressure. The cellulose precipitates in fibre form as the solvent is diluted, and can then be purified and dried. The solvent is later removed and recycled.

The first Lyocell-type fibre to be produced commercially was Acordis Tencel in 1992. These fibres have a higher wet and dry tensile strength than any other cellulosic fibres. They exhibit low shrinkage in water and have a high number of crystalline regions, which gives rise to the characteristic fibrillation. The fibres become abraded in the wet state causing surface fibrils to peel away, but remain attached to the fibre’s surface. The fibrils splitting away from the fibre surface manifest as a frosty-looking surface, preventing the true dyed colour from emerging.
Early on, this was deemed an unacceptable fabric appearance and texture, but enzyme and mechanical treatments were developed to vary the extent of fibrillation, giving rise to special effects such as ‘peach skin’, soft touch, sand-washed and the ‘used’ look.

Potential uses for Lyocell fall into many categories. Woven apparel for sportswear and bedding, due to high moisture absorption and dissipation are foremost. Lyocell fibres can be blended with most natural fibres, and can be dyed with indigo to produce a fabric that looks like denim but has a silky feel - this was not previously possible, with any other cellulosic fibre except cotton. Acordis and Lenzing are now producing new non-fibrillating versions, called TencelA100 and Lyocell LF, respectively.

References

GRIEVE, M.C., 1999, New Fibre Types, Forensic Examination of Fibres, Taylor and Francis Publishing, London, 399 – 419.

ACORDIS, 2003, Information from the website of Acordis http://www.tencel.com, April 2003.

Adapted from my research essay entitled "Forensic examination of new fibres" University of Auckland

Lyocell is a fiber made from the cellulose in wood pulp. This fiber is used to create yarns that are then made into fabrics from which clothing and other textile items can be made. It is considered to be an environmentally friendly product. The wood pulp comes from managed forests, the low-impact production process uses non-toxic materials, and the final product is biodegradable.

Lyocell clothing is usually machine washable on the gentle cycle, but check the tags, as linings or other aspects of its fabrication may require the item to be hand washed or dry cleaned. Drip dry, though you can usually put the already dry article into a clothes dryer with a damp towel for a few minutes to loosen it up. It dries very quickly, resists shrinkage, is wrinkle-resistant and it wears like iron.

I can tell you from personal experience that it is lightweight, breathes well, and is very soft. It is absorbent, but yet it doesn't race to show perspiration, either. It looks, drapes, and feels like heavy silk — in other words, it is outrageously comfortable. If I could, I’d have all my clothing made from it!

A common trade name for lyocell is Tencel®.

Reference: www.tencel.com