Lyocell fiber
Lyocell fiber is a form of rayon made up of cellulose fiber, which is made from molten
pulp and then reconstituted by dry jet-weight spinning. Fiber is used to make
textiles for clothing and other purposes. Unlike rayon produced by the viscose
process, lyocell production does not use harmful carbon disulfide, which is
toxic to workers and the environment. In 2018, the lyocell fiber process was
more expensive than the most common viscose fiber process for making rayon.
Lyocell
has become a genericized trademark that is used to refer to the process of
making cellulose fibers. The US Federal Trade Commission defines lyocell as a
fiber composed of cellulose made from an organic solution where no substitution
of hydroxyl groups occurs and no chemical mediation is formed. It classifies
fibers as a subclass of rayon.
Lyocell fiber History
The
lyocell process was created in 1972 by a team at the now-defunct American Enka
Fiber facility in Enka, North Carolina. In 2003, the American Association of
Textile Chemists and Colorists (AATCC) awarded Neil E. Frank their Henry E.
Milson Award for lyocell Innovation. In 1966-1968, Eastman Kodak Inc.'s D.L.
Johnson researched NMMO solutions. From 1969 to 1979, the American Enka tried
unsuccessfully to commercialize the process. The operating name for the fiber
within the Enka Company was Newcell and was developed through a pilot plant
scale before the work was discontinued.
The
initial process of dissolving cellulose in NMMO was first described in 1981 in
a Mcorsley patent for Akzona Inc. The patent was licensed to Cortoulds and
Lenzing by Akzo in the 1980s. The fiber was made in the 1980s by Courtaulds
Fibers under the Tencel brand. In 1982, a 100 kg/week pilot plant was built in
Coventry, UK, and in 1984 production increased tenfold. In 1988, a 25-ton/week
semi-commercial production line was opened at the Grimsby, UK, pilot plant.
The
process was first commercialized in Mobile, Alabama, and at the Grimsby Plant
(1998) rayon factory in Courtaulds. In January 1993, the mobile Tencel plant
reached a full production level of 20,000 tons per year, during which time
Courtaulds spent £100 million and 10 years developing the Tencel. Tencel
revenue for 1993 was estimated at £50 million. The second plant was planned on
mobile. By 2004, production had quadrupled to 80,000 tons.
Lyocell fiber properties
i.
Lyocell fiber is similar in many respects to viscose rayon fiber but exhibits
enhanced properties in terms of softness, drapability, dimensional durability,
dye acceptance, and colorfastness.
ii.
Moisture regain of lyocell fiber is about 11%, slightly less than
viscose-rayon.
iii.
The dry tenacity value of lyocell fiber is higher than that of viscose and HWM
rayon fiber.
iv.
It is the only regenerated cellulose fiber that has a wet tensile strength
greater than the wet energy of cotton.
v.
It has a significantly reduced elongation value slightly higher than HWM rayon fiber.
vi.
It has a close to circular cross-section that's longitudinal surface is very
smooth and cylindrical without any striation.
vii.
It can be hand washable
viii.
It is fibrillated during wet processing to produce special textures.
ix.
It is also biodegradable.
Lyocell fiber description
Lyocell
fibers are produced by regenerating cellulose into an organic solvent, N-methyl morpholine-N-oxide hydrate, which is non-toxic and biodegradable, and
almost completely recyclable. The life cycle of a lyocell fiber has a minimal
environmental impact and is significantly more durable than natural fibers such
as synthetic fibers or cotton derived from oil; it uses less land, irrigation,
pesticides, or fertilizers to grow eucalyptus or beech trees from which lyocell
fiber is made if the forests are managed sustainably in the case of cotton.
Lyocell Fiber is available as Tensile, Lyocell, and Newcell; 98% of lyocell
fiber production is responsible for Lenzing.
Due
to their high crystallinity compared to other cellulosic fibers, unchanged
lyocell-type fibers can be easily fibrillated by any mechanical action on the
surface of the woven fabric. Fibrillated lyocell always shows lower visual
color yields than their non-fibrillated counterparts because of lighter
scattering. Fibrillation is usually uneven; so the Lenzing enzyme treats the
fabric to remove the surface fuzz, then gives it a mechanical push to achieve a
more regular effect. Fibrillation is useful for creating the effect of the popular
suede or peach-skin surface, which can be accomplished by dyeing methods
instead of by individual enzyme treatment and mechanical friction. As a result,
lyocell fibers have become popular for certain styles: for example, in the
production of fashion jeans with a pleasing soft handle compared to those made
from cotton.
Lyocell fiber manufacturing process
Lyocell
Fiber was first developed and manufactured by Courtaulds Fibers in the UK in
the 1980s as Tensile Fiber. Lenzing AG, Austria manufactures Lyocell under the
brand name Lyocell by Lenzing. The generic name is lyocell, and the fibers are
manufactured under brand names including special brands including Tencel,
Lanzing Lyocell, Newcell, and Seacell. Lyocell and viscose are made from wood
pulp but have different manufacturing processes. Lyocell is produced by a
direct dissolving process and no derivatives are involved as opposed to viscose
rayon.
A
solution of hot N-Methylmorpholine-N-oxide (NMMO), a cyclic amine oxide that
has proven to be an excellent solvent for cellulose, is used to dissolve wood
pulp. The viscous solution, after being filtered, is spun into a coagulation
bath of the aqueous solution of the amine oxide. The spinning process is
followed by washing and drying the filaments. The process offers the advantage
of a low number of processing stages, about 99% solvent recovery, and the fiber
properties are unmatched by the classic manufacturing processes. Only a very
small amount of NMMO remains in waste water, which is treated more
biologically. Lyocell fibers benefit from their properties and eco-friendly
manufacturing processes. Fibrillation, one of the most important features of
lyocell fibers, can be used to create an attractive fabric touch called the
peach-skin effect.
Lyocell fabric test
The
nature or generic type of cellulosic material can be determined by a burning
test and then the longitudinal feature can be observed by microscopic
examination, which refers to data from fibers like modal, bamboo, chitin,
cotton, and regular viscose fibers. Sodium hypochlorite can be used as a
solvent to further investigate dissolved behavior. Also, a tensile test can be
performed to find out the strength of the fibers, since the strength of the
lyocell fibers is the highest among the cellulosic fibers.
Lyocell fiber advantages
i.
Lyocell fabric is considered a durable fabric because it is made of wood and
therefore biodegradable and compostable.
ii.
It can be blended with other fabrics like cotton, polyester, acrylic, ethical
wool, and peace silk
iii.
It is breathable, strong, and gentle on the skin with a soft, silky texture
iv.
It is stretched and efficient in absorbing moisture, making it a great
alternative to activewear
v.
Instead of viscose and other types of rayon, lyocell is made using a
closed-loop process which means that the chemicals used in the production are
not released into the environment.
Lyocell fiber disadvantages
i.
A major disadvantage is that lyocell is not as economical as other fibers like
cotton at present.
ii.
Although the lyocell itself is compostable if mixed with other synthetic
fibers, the new fabric will not be compostable.
iii.
Uses a lot of energy in the production of lyocell
iv. Lyocell is a delicate fabric so recommend using a cold wash and no dryer.
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