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Rayon is a semi-synthetic fiber, made from natural sources of regenerated
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
, such as wood and related agricultural products. It has the same molecular structure as cellulose. It is also called viscose. Many types and grades of viscose fibers and films exist. Some imitate the feel and texture of natural fibers such as
silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from th ...
,
wool Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal wool. ...
,
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...
, and
linen Linen () is a textile made from the fibers of the flax plant. Linen is very strong, absorbent, and dries faster than cotton. Because of these properties, linen is comfortable to wear in hot weather and is valued for use in garments. It also ...
. The types that resemble silk are often called artificial silk. The fibre is used to make textiles for clothing and other purposes. Rayon production involves
solubilizing Micellar solubilization (solubilization) is the process of incorporating the solubilizate (the component that undergoes solublization) into or onto micelles. Solublization may occur in a system consisting of a solvent, an association colloid (a c ...
cellulose to allow turning the fibers into required form. Three common ways to solubilize are the cuprammonium process, not in use today, using
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...
cal solutions of copper salts; the viscose process, the most common today, using alkali and
carbon sulfide Carbon sulfide may refer to: * Carbon disulfide * Carbon monosulfide * Carbon subsulfide * Sulflower Sulflower (a portmanteau of sulfur and sunflower) is a stable heterocyclic octacirculene based on thiophene. Sulflower does not contain any hydr ...
; and the
Lyocell Lyocell, originally trademarked in 1982 as Tencel, is a form of regenerated cellulose. It consists of cellulose fibers, made by dissolving pulp and then reconstituting it by dry jet-wet spinning. The fiber is used to make textiles for clothing a ...
process, using amine oxide. The last avoids the neurotoxic carbon sulfide of the viscose process but is also more expensive.


Rayon and its variants

Rayon is produced by dissolving cellulose, then converting this solution back to insoluble fibrous cellulose. Various processes have been developed for this regeneration. The most common methods for creating rayon are the cuprammonium method, the viscose method, and the lyocell process. The first two methods have been practiced for more than a century.


Cuprammonium methods

Swiss
chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...
Matthias Eduard Schweizer Matthias Eduard Schweizer (8 August 1818 – 23 October 1860) was a Swiss chemist who in 1857 invented Schweizer's reagent, in which cellulose can be dissolved to produce artificial silk or rayon. He was one of the pioneers of the synthetic tex ...
(1818–1860) discovered that cellulose dissolves in tetraaminecopper dihydroxide. Max Fremery and Johann Urban developed a method to produce
carbon fiber Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
s for use in
light bulb An electric light, lamp, or light bulb is an electrical component that produces light. It is the most common form of artificial lighting. Lamps usually have a base made of ceramic, metal, glass, or plastic, which secures the lamp in the soc ...
s in 1897. Production of cuprammonium rayon for textiles started in 1899 in the Vereinigte Glanzstoff Fabriken AG in Oberbruch near
Aachen Aachen ( ; ; Aachen dialect: ''Oche'' ; French and traditional English: Aix-la-Chapelle; or ''Aquisgranum''; nl, Aken ; Polish: Akwizgran) is, with around 249,000 inhabitants, the 13th-largest city in North Rhine-Westphalia, and the 28th ...
. Improvement by J. P. Bemberg AG in 1904 made the artificial silk a product comparable to real silk.''J. P. Bemberg AG'' was one of the ''
Vereinigte Glanzstoff-Fabriken Vereinigte Glanzstoff-Fabriken (VGF, United Rayon Factories) was a German manufacturer of artificial fiber founded in 1899 that became one of the leading European producers of rayon. During the first thirty years VGF cooperated closely with the Br ...
'' which merged into the Dutch based ''Algemene Kunstzijde Unie'' (AKU)—
AkzoNobel Akzo Nobel N.V., stylized as AkzoNobel, is a Dutch multinational company which creates paints and performance coatings for both industry and consumers worldwide. Headquartered in Amsterdam, the company has activities in more than 80 countries, ...
today.
Cuprammonium rayon has properties similar to viscose; however, during its production, the cellulose is combined with
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
and
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...
( Schweizer's reagent). Due to the detrimental environmental effects of this production method, cuprammonium rayon is no longer being produced in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
. The process has been described as historic, but cuprammonium rayon is still made by one company in Japan. Tetraamminecopper(II) sulfate is also used as a solvent.


Viscose method

English chemist
Charles Frederick Cross Charles Frederick Cross FRS (11 December 1855 – 15 April 1935) was a British chemist. Born in Brentford, Middlesex, his fatherCharles James Cross (14 October 1827 - 19 November 1910) was a schoolmaster turned soap manufacturer. After graduatin ...
and his collaborators, Edward John Bevan and Clayton Beadle, patented their artificial
silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from th ...
in 1894. They named their material "viscose" because its production involved the intermediacy of a highly viscous solution. The process built on the reaction of
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
with a strong base, followed by treatment of that solution with carbon disulfide to give a xanthate derivative. The xanthate is then converted back to a cellulose fiber in a subsequent step. The first commercial viscose rayon was produced by the UK company Courtaulds Fibres in November 1905. Courtaulds formed an American division, American Viscose (later known as Avtex Fibers), to produce their formulation in the United States in 1910. The name "rayon" was adopted in 1924, with "viscose" being used for the viscous organic liquid used to make both rayon and cellophane. In Europe, though, the fabric itself became known as "viscose", which has been ruled an acceptable alternative term for rayon by the US
Federal Trade Commission The Federal Trade Commission (FTC) is an independent agency of the United States government whose principal mission is the enforcement of civil (non-criminal) antitrust law and the promotion of consumer protection. The FTC shares jurisdiction o ...
(FTC). The viscose method can use
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...
as a source of cellulose, whereas other routes to rayon require
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity a ...
-free cellulose as a starting material. The use of woody sources of cellulose makes viscose cheaper, so it was traditionally used on a larger scale than the other methods. On the other hand, the original viscose process generates large amounts of contaminated wastewater. Newer technologies use less water and have improved the quality of the wastewater. Rayon was produced only as a filament fiber until the 1930s when methods were developed to utilize "broken waste rayon" as staple fiber.


Structurally modified viscose

The physical properties of rayon remained unchanged until the development of high-tenacity rayon in the 1940s. Further research and development led to high-wet-modulus rayon (HWM rayon) in the 1950s. Research in the UK was centred on the government-funded British Rayon Research Association. ''High-tenacity rayon'' is another modified version of viscose that has almost twice the strength of HWM. This type of rayon is typically used for industrial purposes such as tire cord. Industrial applications of rayon emerged around 1935. Substituting cotton fiber in tires and belts, industrial types of rayon developed a totally different set of properties, amongst which tensile strength and elastic modulus were paramount. Modal is a genericized trademark of Lenzing AG, used for (viscose) rayon which is stretched as it is made, aligning the molecules along the fibers. Two forms are available: "polynosics" and "high wet modulus" (HWM). ''High-wet-modulus rayon'' is a modified version of viscose that is stronger when wet. It can be
mercerized Mercerisation is a textile finishing treatment for cellulose fabric and yarn, mainly cotton and flax, which improves dye uptake and tear strength, reduces fabric shrinkage, and imparts a silk-like luster. Development The process was devis ...
like cotton. HWM rayons are also known as "polynosic". Polynosic fibers are dimensionally stable and do not shrink or get pulled out of shape when wet like many rayons. They are also wear-resistant and strong while maintaining a soft, silky feel. They are sometimes identified by the trade name Modal.Joyce A. Smith
"Rayon – The Multi-Faceted Fiber"
Ohio State University Rayon Fact Sheet.
Modal is used alone or with other fibers (often cotton or spandex) in clothing and household items like pajamas, underwear, bathrobes, towels, and bedsheets. Modal can be tumble-dried without damage. The fabric has been known to pill less than cotton due to fiber properties and lower surface friction. Modal is made by spinning beech-tree cellulose and is considered a more eco-friendly alternative to cotton, as the production process uses on average 10–20 times less water.


Lyocell method

The
lyocell Lyocell, originally trademarked in 1982 as Tencel, is a form of regenerated cellulose. It consists of cellulose fibers, made by dissolving pulp and then reconstituting it by dry jet-wet spinning. The fiber is used to make textiles for clothing a ...
process relies on dissolution of cellulose products in a solvent, N-methyl morpholine N-oxide (NMMO). The lyocell process is not widely used because it is more expensive than the viscose process. The process starts with cellulose and involves dry jet-wet spinning. It was developed at the now defunct American Enka Company and
Courtaulds Courtaulds was a United Kingdom-based manufacturer of fabric, clothing, artificial fibres, and chemicals. It was established in 1794 and became the world's leading man-made fibre production company before being broken up in 1990 into Courtaulds ...
Fibres. Lenzing's Tencel is an example of a lyocell fiber. Unlike the viscose process, the lycocell process does not use highly toxic carbon sulfide. "Lyocell" has become a genericized trademark, used to refer to the lyocell process for making cellulose fibers.


Related materials

Related materials are not regenerated cellulose, but esters of cellulose.


Nitrocellulose

Nitrocellulose Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...
is a derivative of cellulose that is soluble in organic solvents. It is mainly used as an explosive or as a
lacquer Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity. Asian lacquerware, which may be c ...
. Many early plastics, including celluloid, were made from nitrocellulose.


Acetate

Cellulose acetate shares many similarities with viscose rayon and was formerly considered as the same textile. However, rayon resists heat, while acetate is prone to melting. Acetate must be laundered with care either by hand-washing or dry cleaning, and acetate garments disintegrate when heated in a tumble dryer. The two fabrics are now required to be listed distinctly on garment labels.


Cellophane

Cellophane is generally made by the viscose process, but dried into sheets instead of fibers.


Major fiber properties

Rayon is a versatile fiber and is widely claimed to have the same comfort properties as natural fibers, although the drape and slipperiness of rayon textiles are often more like
nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from pet ...
. It can imitate the feel and texture of
silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from th ...
,
wool Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal wool. ...
,
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...
and
linen Linen () is a textile made from the fibers of the flax plant. Linen is very strong, absorbent, and dries faster than cotton. Because of these properties, linen is comfortable to wear in hot weather and is valued for use in garments. It also ...
. The fibers are easily
dyed Dyeing is the application of dyes or pigments on textile materials such as fibers, yarns, and fabrics with the goal of achieving color with desired color fastness. Dyeing is normally done in a special solution containing dyes and particular ...
in a wide range of colors. Rayon fabrics are soft, smooth, cool, comfortable, and highly absorbent, but they do not always insulate body heat, making them ideal for use in hot and humid climates, although also making their "hand" (feel) cool and sometimes almost slimy to the touch. The durability and appearance retention of regular viscose rayons are low, especially when wet; also, rayon has the lowest elastic recovery of any fiber. However, HWM rayon (high-wet-modulus rayon) is much stronger and exhibits higher durability and appearance retention. Recommended care for regular viscose rayon is dry-cleaning only. HWM rayon can be machine-washed. Image:Rayon_closeup_1.jpg, A sample of rayon from a skirt photographed with a macro lens. Image:Rayon_closeup_2.jpg, Another skirt with a different texture. Image:Rayon_closeup_3.jpg, A blouse with a texture similar to the second. Regular rayon has lengthwise lines called striations and its cross-section is an indented circular shape. The cross-sections of HWM and cupra rayon are rounder. Filament rayon
yarn Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. Thread is a type of yarn intended for sewing by hand or machine. Modern manu ...
s vary from 80 to 980 filaments per yarn and vary in size from 40 to 5000 denier. Staple fibers range from 1.5 to 15 denier and are mechanically or chemically crimped. Rayon fibers are naturally very bright, but the addition of delustering pigments cuts down on this natural brightness.


Manufacture

The raw material for viscose is primarily
wood pulp Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw ...
(sometimes bamboo pulp), which is chemically converted into a soluble compound. It is then dissolved and forced through a
spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and are ...
to produce filaments, which are chemically solidified, resulting in fibers of nearly pure cellulose. Unless the chemicals are handled carefully, workers can be seriously harmed by the carbon disulfide used to manufacture most rayon. To prepare viscose, pulp is treated with aqueous sodium hydroxide (typically 16–19% by mass) to form "alkali cellulose", which has the approximate formula 6H9O4−ONasub>. This material is allowed to depolymerize to an extent. The rate of depolymerization (ripening or maturing) depends on temperature and is affected by the presence of various inorganic additives, such as metal oxides and hydroxides. Air also affects the ripening process, since oxygen causes depolymerization. The alkali cellulose is then treated with carbon disulfide to form sodium cellulose xanthate: Rayon fiber is produced from the ripened solutions by treatment with a mineral acid, such as
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
. In this step, the xanthate groups are hydrolyzed to regenerate cellulose and carbon disulfide: Aside from regenerated cellulose, acidification gives
hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The under ...
(H2S), sulfur, and carbon disulfide. The thread made from the regenerated cellulose is washed to remove residual acid. The sulfur is then removed by the addition of
sodium sulfide Sodium sulfide is a chemical compound with the formula Na2 S, or more commonly its hydrate Na2S·9 H2O. Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are gene ...
solution, and impurities are oxidized by bleaching with sodium hypochlorite solution or
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3 ...
solution. Production begins with processed cellulose obtained from wood pulp and plant fibers. The cellulose content in the pulp should be around 87–97%. The steps: # Immersion: The cellulose is treated with caustic soda. # Pressing. The treated cellulose is then pressed between rollers to remove excess liquid. # The pressed sheets are crumbled or shredded to produce what is known as "white crumb". # The "white crumb" is aged through exposure to
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
. This is a depolymerization step and is avoided in the case of polynosics. # The aged "white crumb" is mixed in vats with carbon disulfide to form the xanthate (see chemical equation above). This step produces "orange-yellow crumb". # The "yellow crumb" is dissolved in a caustic solution to form viscose. The viscose is set to stand for a period of time, allowing it to "ripen". During this stage the molecular weight of the polymer changes. # After ripening, the viscose is filtered, degassed, and then extruded through a
spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and are ...
into in a bath of
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
, resulting in the formation of rayon filaments. The acid is used as a regenerating agent. It converts cellulose xanthate back to cellulose. The regeneration step is rapid, which doesn't allow proper orientation of cellulose molecules. So to delay the process of regeneration, zinc sulfate is used in the bath, which converts cellulose xanthate to zinc cellulose xanthate, thus providing time for proper orientation to take place before regeneration. # ''Spinning.'' The spinning of viscose rayon fiber is done using a wet-spinning process. The filaments are allowed to pass through a coagulation bath after extrusion from the spinneret holes. The two-way mass transfer takes place. # ''Drawing.'' The rayon filaments are stretched, in a procedure known as drawing, to straighten out the fibers. # ''Washing.'' The fibers are then washed to remove any residual chemicals from them. # ''Cutting.'' If filament fibers are desired, then the process ends here. The filaments are cut down when producing staple fibers.


Carbon disulfide toxicity

Carbon disulfide is highly toxic. It is well-documented to have seriously harmed the health of rayon workers in developed countries (see history section), and emissions may also harm the health of people living near rayon plants and their livestock.Supreme Court of Alabama
''Courtaulds Fibers, Inc. v. Horace L. Long, Jr., et al.''; ''Horace L. Long, Jr., et al. v. Courtaulds Fibers, Inc.''
1971996 and 1972028. Decided: September 15, 2000.
Rates of disability in modern factories (mainly in China, Indonesia, and India) are unknown. This has raised ethical concerns over viscose rayon production. , production facilities located in developing countries generally do not provide environmental or worker safety data. Most global carbon disulfide emissions come from rayon production, as of 2008. , about 250 g of carbon disulfide is emitted per kilogram of rayon produced. Control technologies have enabled improved collection of carbon disulfide and reuse of it, resulting in a lower emissions of carbon disulfide. These have not always been implemented in places where it was not legally required and profitable. Carbon disulfide is volatile and is lost before the rayon gets to the consumer; the rayon itself is basically pure
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
.


History


Viscoses

French scientist and industrialist
Hilaire de Chardonnet Louis-Marie Hilaire Bernigaud de Grange, Count (''Comte'') de Chardonnet (1 May 1839 – 11 March 1924) was a French engineer and industrialist from Besançon, and inventor of artificial silk. In the late 1870s, Chardonnet was working with Lo ...
(1838–1924), inventor of the first artificial textile fiber, ''artificial silk'', created viscose. British scientists
Charles Frederick Cross Charles Frederick Cross FRS (11 December 1855 – 15 April 1935) was a British chemist. Born in Brentford, Middlesex, his fatherCharles James Cross (14 October 1827 - 19 November 1910) was a schoolmaster turned soap manufacturer. After graduatin ...
and Edward John Bevan took out British Patent No. 8,700, "Improvements in Dissolving Cellulose and Allied Compounds" in May, 1892. In 1893, they formed the Viscose Syndicate to grant licences and, in 1896, formed the British Viscoid Co. Ltd. to exploit the process. Studies from the 1930s show that 30% of American rayon workers suffered severe health effects from carbon disulfide exposure.
Courtaulds Courtaulds was a United Kingdom-based manufacturer of fabric, clothing, artificial fibres, and chemicals. It was established in 1794 and became the world's leading man-made fibre production company before being broken up in 1990 into Courtaulds ...
worked hard to prevent this information being published in Britain. During the
Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...
, political prisoners in
Nazi Germany Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...
were made to work in appalling conditions at the Phrix rayon factory in
Krefeld Krefeld ( , ; li, Krieëvel ), also spelled Crefeld until 1925 (though the spelling was still being used in British papers throughout the Second World War), is a city in North Rhine-Westphalia, Germany. It is located northwest of Düsseldorf, ...
. Nazis used forced labour to produce rayon across occupied Europe. In the 1990s, viscose rayon producers faced lawsuits for negligent environmental pollution. Emissions abatement technologies had been consistently used. Carbon-bed recovery, for instance, which reduces emissions by about 90%, was used in Europe, but not in the US, by Courtaulds. Pollution control and worker safety started to become cost-limiting factors in production. Japan has reduced carbon disulfide emissions per kilogram of viscose rayon produced (by about 16% per year), but in other rayon-producing countries, including China, emissions are uncontrolled. Rayon production is steady or decreasing except in China, where it is increasing, . Rayon production has largely moved to the developing world, especially China, Indonesia and India. Rates of disability in these factories are unknown, , and concerns for worker safety continue.


Lyocell

The development of lyocell was motivated by environmental concerns; researchers sought to manufacture rayon by means less harmful than the viscose method.Johnathan Y. Chen. Textiles and fashion: materials, design and technology, 2015. As quote
by Elsevier
/ref> The lyocell process was developed in 1972 by a team at the now defunct American Enka fibers facility at
Enka, North Carolina Enka is an unincorporated community in Buncombe County, North Carolina, United States. It lies on U.S. Routes 19, 23, and 74 Business near the interchange of Interstates 26, 40, and 240. It has a post office with the ZIP code 28728. Histo ...
. In 2003, the
American Association of Textile Chemists and Colorists AATCC—the American Association of Textile Chemists and Colorists— is a 501(c)(6) not-for-profit professional association that provides test method development, quality control materials, educational development, and networking for textile and a ...
(AATCC) awarded Neal E. Franks their Henry E. Millson Award for Invention for lyocell. In 1966–1968, D. L. Johnson of Eastman Kodak Inc. studied NMMO solutions. In the decade 1969 to 1979, American Enka tried unsuccessfully to commercialize the process. The operating name for the fibre inside the Enka organization was "Newcell", and the development was carried through pilot plant scale before the work was stopped. The basic process of dissolving cellulose in NMMO was first described in a 1981 patent by Mcorsley for Akzona Incorporated (the holding company of Akzo). In the 1980s the patent was licensed by Akzo to Courtaulds and Lenzing. The fibre was developed by
Courtaulds Courtaulds was a United Kingdom-based manufacturer of fabric, clothing, artificial fibres, and chemicals. It was established in 1794 and became the world's leading man-made fibre production company before being broken up in 1990 into Courtaulds ...
Fibres under the brand name "Tencel" in the 1980s. In 1982, a 100kg/week pilot plant was built in Coventry, UK, and production was increased tenfold (to a ton/week) in 1984. In 1988, a 25 ton/week semi-commercial production line opened at the Grimsby, UK, pilot plant. The process was first commercialised at Courtaulds' rayon factories at
Mobile, Alabama Mobile ( , ) is a city and the county seat of Mobile County, Alabama, United States. The population within the city limits was 187,041 at the 2020 census, down from 195,111 at the 2010 census. It is the fourth-most-populous city in Alabama ...
(1990), and at the Grimsby plant (1998). In January 1993, the Mobile Tencel plant reached full production levels of 20,000 tons per year, by which time Courtaulds had spent £100 million and 10 years on Tencel development. Tencel revenues for 1993 were estimated as likely to be £50 million. A second plant in Mobile was planned. By 2004, production had quadrupled to 80,000 tons. Lenzing began a pilot plant in 1990, and commercial production in 1997, with 12 metric tonnes/year made in a plant in Heiligenkreuz im Lafnitztal, Austria. When an explosion hit the plant in 2003 it was producing 20,000 tonnes/year, and planning to double capacity by the end of the year. In 2004 Lenzing was producing 40,000
ton Ton is the name of any one of several units of measure. It has a long history and has acquired several meanings and uses. Mainly it describes units of weight. Confusion can arise because ''ton'' can mean * the long ton, which is 2,240 pounds ...
s ic, probably metric tonnes In 1998, Lenzing and Courtaulds reached a patent dispute settlement. In 1998 Courtaulds was acquired by competitor Akzo Nobel, which combined the Tencel division with other fibre divisions under the Accordis banner, then sold them to private equity firm
CVC Partners CVC may refer to: Science and technology * Compact Video Cassette, a quarter-inch video cassette format * Card verification code, a security feature on credit cards * Card Verifiable Certificate, a format for digital certificates usable by smar ...
. In 2000, CVC sold the Tencel division to Lenzing AG, which combined it with their "Lenzing Lyocell" business, but maintained the brand name Tencel. It took over the plants in Mobile and Grimsby, and by 2015 were the largest lyocell producer at 130,000 tonnes/year. , the lyocell process is not widely used, because it is still more expensive than the viscose process.


Disposal and biodegradability

The biodegradability of various fibers in soil burial and sewage sludge was evaluated by Korean researchers. Rayon was found to be more biodegradable than cotton, and cotton more than acetate. The more water-repellent the rayon-based fabric, the more slowly it will decompose.
Silverfish The silverfish (''Lepisma saccharinum'') is a species of small, primitive, wingless insect in the order Zygentoma (formerly Thysanura). Its common name derives from the insect's silvery light grey colour, combined with the fish-like appearance ...
—like the
firebrat The firebrat (''Thermobia domestica'') is a small hexapod (typically 1–1.5 cm), in the order Zygentoma. Habitat Firebrats prefer higher temperatures and require some humidity, and can be found in bakeries and near boilers or fur ...
—can eat rayon, but damage was found to be minor, potentially due to the heavy, slick texture of the tested rayon. Another study states that "artificial silk .. asreadily eaten" by the grey silverfish. A 2014 ocean survey found that rayon contributed to 56.9% of the total fibers found in deep ocean areas, the rest being
polyester Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natura ...
, polyamides, acetate and
acrylic Acrylic may refer to: Chemicals and materials * Acrylic acid, the simplest acrylic compound * Acrylate polymer, a group of polymers (plastics) noted for transparency and elasticity * Acrylic resin, a group of related thermoplastic or thermosett ...
.Abundance of microplastics in the world's deep seas
(2014-12-16). Retrieved on 2014-12-17.
A 2016 study found a discrepancy in the ability to identify natural fibers in a marine environment via Fourier transform infrared spectroscopy. Later research of oceanic microfibers instead found cotton being the most frequent match (50% of all fibers), followed by other cellulosic fibers at 29.5% (e.g., rayon/viscose, linen, jute, kenaf, hemp, etc.). Further analysis of the specific contribution of rayon to ocean fibers was not performed due to the difficulty in distinguishing between natural and man-made cellulosic fibers using FTIR spectra.


Sustainable forestry

For several years, there have been concerns about links between rayon manufacturers and deforestation. As a result of these concerns, FSC and PEFC came on the same platform with CanopyPlanet to focus on these issues. CanopyPlanet subsequently started publishing a yearly Hot Button report, which puts all the man-made cellulosics manufacturers globally on the same scoring platform. The scoring from the 2020 report scores all such manufacturers on a scale of 35, the highest scores having been achieved by Birla Cellulose (33) and
Lenzing Lenzing is a small town of approximately 5,000 residents, three kilometers north of Lake Attersee in Austria, It is located in the Upper Austrian part of the Salzkammergut. Lenzing's economy is partly based on tourism, but the town is much mo ...
(30.5).


Producers and brandnames

In 2018, viscose fiber production in the world was approximately 5.8 million tons, and
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
was the largest producer with about 65% of total global production. Trade names are used within the rayon industry to label the type of rayon in the product. Viscose Rayon was first produced in Coventry England in 1905 by Courtaulds. ''Bemberg'' is a trade name for cupramonium rayon developed by J. P. Bemberg. Bemberg performs much like viscose but has a smaller diameter and comes closest to silk in feel. Bemberg is now only produced in Japan. The fibers are finer than viscose rayon. '' Modal'' and '' Tencel'' are widely used forms of rayon produced by Lenzing AG. Tencel, generic name ''lyocell'', is made by a slightly different solvent recovery process, and is considered a different fiber by the US FTC. Tencel lyocell was first produced commercially by Courtaulds' Grimsby plant in England. The process, which dissolves cellulose without a chemical reaction, was developed by Courtaulds Research. Birla Cellulose is also a volume manufacturer of rayon. They have plants located in
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
,
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
and
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
. Accordis was a major manufacturer of cellulose-based fibers and yarns. Production facilities can be found throughout Europe, the U.S. and
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
. ''Visil rayon'' and HOPE FR are flame retardant forms of viscose that have
silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
embedded in the fiber during manufacturing. North American Rayon Corporation of
Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. Tennessee is the List of U.S. states and territories by area, 36th-largest by ...
produced viscose rayon until its closure in the year 2000.North American Rayon Corporation and American Bemberg Corporation
in the Tennessee Encyclopedia
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
is one of the largest producers of rayon in the world, and Asia Pacific Rayon (APR) of the country has an annual production capacity of 0.24 million tons.


See also

* Cellophane – sheet-extruded viscose rayon *
Hilaire de Chardonnet Louis-Marie Hilaire Bernigaud de Grange, Count (''Comte'') de Chardonnet (1 May 1839 – 11 March 1924) was a French engineer and industrialist from Besançon, and inventor of artificial silk. In the late 1870s, Chardonnet was working with Lo ...
– inventor of artificial silk *
Nitrocellulose Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...
– another form of modified cellulose *
Polyester Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natura ...
– another synthetic fiber frequently used for textiles *
Ray P. Dinsmore Ray Putnam Dinsmore (24 April 1893 – 26 October 1979) was a rubber scientist, known for pioneering the use of rayon as a reinforcing material in auto tires. In 1928, Dinsmore patented the first water-emulsion synthetic rubber in the United Stat ...
– pioneered use of Rayon in tires


References


Further reading

* *Gupta, VB; Kothari, VK and Sengupta, AK eds. (1997) ''Manufactured Fibre Technology''. Chapman & Hall, London. . * For a review of all rayon production methods and markets se
"Regenerated Cellulose Fibres"
(book – Edited by C R Woodings) Hardback 2001, , Woodhead Publishing Ltd. * For a description of the production method at a factory in Germany in
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, see Agnès Humbert (tr. Barbara Mellor) ''Résistance: Memoirs of Occupied France'', London, Bloomsbury Publishing PLC, 2008 (American title: ''Resistance: A Frenchwoman's Journal of the War'', Bloomsbury, USA, 2008) pp. 152–155 * For a complete set of photographs of the process se
"The Story of Rayon" published by Courtaulds Ltd (1948)
* Arnold Hard, the textile journalist, produced two books documenting the experiences of some of the pioneers in the early British rayon industry the Hard, Arnold. H. (1933). ''The Romance of Rayon''. Whittaker & Robinson, Manchester and Hard, Arnold (1944) ''The Story of Rayon'', United Trade Press Ltd, London


External links


{{Authority control Organic polymers Cellulose Synthetic fibers Products introduced in 1891 Articles containing video clips Pulp and paper industry