Editing Lyocell

{{Short description|Regenerated cellulose fibre made from dissolving pulp}}
{{EngvarB|date=May 2025}}
{{Use dmy dates|date=May 2025}}
[[File:Lyocell Vital fabric.jpg|thumb|upright|Mattress with Lyocell as cover material]]
[[File:Lyocell.jpg|thumb|upright|Label of a coat containing Tencel (a brand of Lyocell)]]

'''Lyocell''' is a [[Fiber#Semi-synthetic fibers|semi-synthetic fibre]] used to make textiles for clothing and other purposes.<ref>{{Ullmann |first1=Hans |last1=Krässig |first2=Josef |last2=Schurz |first3=Robert G. |last3=Steadman |first4=Karl |last4=Schliefer|first5=Wilhelm|last5=Albrecht|first6=Marc|last6=Mohring|first7=Harald |last7=Schlosser |title=Cellulose |date=2002 |doi=10.1002/14356007.a05_375.pub2 }}</ref> It is a form of regenerated cellulose made by [[dissolving pulp]] and [[dry jet-wet spinning]]. Unlike [[rayon]], which is made by the more common [[Rayon#Viscose method|viscose]] processes, Lyocell production does not use [[carbon disulfide]],<ref name="brief">{{cite journal |date=2018 |title=Regenerated cellulose by the Lyocell process, a brief review of the process and properties :: BioResources |url=https://bioresources.cnr.ncsu.edu/resources/regenerated-cellulose-by-the-lyocell-process-a-brief-review-of-the-process-and-properties/ |journal=BioRes}}</ref><ref name=thesis>{{cite thesis |last1=Tierney |first1=John William |title=Kinetics of Cellulose Dissolution in N-MethylMorpholine-N-Oxide and Evaporative Processes of Similar Solutions |date=2005 |url=https://trace.tennessee.edu/utk_gradthes/2553/ }}{{pn|date=April 2025}}</ref> which is toxic to workers and the environment.<ref name=Blanc>{{cite news |last1=Swan |first1=Norman |last2=Blanc |first2=Paul |title=The health burden of viscose rayon |url=http://www.abc.net.au/radionational/programs/healthreport/the-health-burden-of-viscose-rayon/8286870 |work=ABC Radio National |date=20 February 2017}}</ref><ref>{{cite news |last1=Nijhuis |first1=Michelle |title=Bamboo Boom: Is This Material for You? |url=https://www.scientificamerican.com/article/bamboo-boom/ |work=Scientific American |date=June 2009 }}</ref><ref name=brief/> Lyocell was originally trademarked as Tencel in 1982.  

"Lyocell" has become a [[Generic trademark|genericised trademark]] used to refer to the Lyocell process for making cellulose fibres.<ref name=thesis/><ref name=merge/> The U.S. [[Federal Trade Commission]] defines Lyocell as "a fiber composed of cellulose precipitated from an organic solution in which no substitution of the [[hydroxy group]]s takes place, and no chemical intermediates are formed". It classifies the fibre as a sub-category of rayon.<ref>{{Cite web |url=http://www.ecfr.gov/cgi-bin/text-idx?SID=bd623b0d99d64f680f4d2b376e0c4d06&node=16:1.0.1.3.27.0.12.7&rgn=div8 |title=16 CFR 303.7(d) |website=ecfr.gov }}</ref>

==Names==
Other trademarked names for Lyocell fibres are '''Tencel''' ([[Lenzing AG]]),<ref>{{Cite web |url=https://www.tencel.com/about|title=What is TENCEL fibers fabric made of? About TENCEL Lyocell & Modal fibers }}</ref> '''Newcell''' ([[Akzo Nobel]]), and '''Seacell''' (Zimmer AG).<ref name=O&A>{{cite book |doi=10.1533/9780857099174.2.174 |chapter=Wet spinning of synthetic polymer fibers |title=Advances in Filament Yarn Spinning of Textiles and Polymers |date=2014 |last1=Ozipek |first1=B. |last2=Karakas |first2=H. |pages=174–186 |isbn=978-0-85709-499-5 }}</ref> The [[Aditya Birla Group]] also sells it under the brand name '''Excel'''.<ref name=good/>
There are other manufacturers like [[Sateri]] which sell their product under generic name '''Lyocell'''<ref>{{Cite web |url=https://www.sateri.com/products/lyocell-fibre/ |title=[:en]Lyocell Fibre[:zh]莱赛尔[:] }}</ref>

==History==
The development of Tencel was motivated by environmental concerns; researchers sought to manufacture rayon by means less harmful than the [[viscose]] method.<ref name=chen>{{cite book |doi=10.1016/B978-1-84569-931-4.00004-0 |chapter=Synthetic Textile Fibers |title=Textiles and Fashion |date=2015 |last1=Chen |first1=J. |pages=79–95 |isbn=978-1-84569-931-4 }}</ref>

The Lyocell process was developed in 1972 by a team at the now defunct [[American Enka Company|American Enka]] fibres facility at [[Enka, North Carolina]]. In 2003, the [[American Association of Textile Chemists and Colorists]] (AATCC) awarded Neal E. Franks their Henry E. Millson Award for Invention for Lyocell.<ref>{{cite web |title=Millson Award for Invention |url=https://aatcc.org/millson/#tab-1 |website=AATCC }}</ref> In 1966–1968, D. L. Johnson of Eastman Kodak Inc. studied [[NMMO]] solutions. From 1969 to 1979, American Enka tried unsuccessfully to commercialise the process.<ref name=chen/> The operating name for the fibre inside the Enka organisation was "Newcell", and the development was carried through a 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<ref name=chen/><ref>{{cite patent|country=US|number=4246221|title=Process for Shaped Cellulose Article Prepared from Solution Containing Cellulose Dissolved in a Tertiary Amine N-oxide Solvent|status=|pubdate=1981|inventor=Mcorsley, C.|url=|class=}} New York, New York, Akzona Incorporated.</ref> (the holding company of Akzo). In the 1980s the patent was licensed by [[Akzo]] to Courtaulds and Lenzing.<ref name=merge/> 

The [[fibre]] was developed by [[Courtaulds]] Fibres under the brand name "Tencel" in the 1980s. In 1982, a 100-kg/week pilot plant was built in Coventry, UK, and production  increased tenfold (to a ton/week) in 1984. In 1988, a 25-ton/week semi-commercial production line opened at the [[Courtaulds, Grimsby|Grimsby, UK, pilot plant]].<ref>{{Cite web|url=http://www.tencel-lyocell.com/p/introducing-tencel.html|title=Introducing Tencel lyocell}}</ref><ref name=chen/>

The process was first<ref name=chen/> commercialised at Courtaulds' rayon factories at [[Mobile, Alabama]]<ref name=nyt/> (1990<ref name=chen/>), and at the Grimsby plant (1998).<ref name=chen/> 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. The second plant in Mobile was planned.<ref name=nyt>{{cite news |last1=Ipsen |first1=Erik |title=International Manager: Freed of Textile Business, Courtaulds Is Doing Fine |url=https://www.nytimes.com/1993/02/25/business/worldbusiness/IHT-international-manager-freed-of-textile-business.html |work=The New York Times |agency=International Herald Tribune |date=25 February 1993 }}</ref> By 2004, production had quadrupled to 80,000 tons.<ref name=merge/> 

Lenzing began a pilot plant in 1990,<ref name=chen/> and commercial production in 1997, with 12 metric tonnes/year made in a plant in [[Heiligenkreuz im Lafnitztal]], Austria.<ref name=chen/><ref name=merge/><ref>{{Cite web |title=Lenzing Group |url=https://www.lenzing.com/lenzing-group/history |access-date=28 July 2022 |website=www.lenzing.com |language=en-US}}</ref> 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.<ref>{{cite news |last1=Beacham |first1=Will |title=Explosion and fire halts 'Lyocell' output at Lenzing's Heiligenkreuz, Austria plant |url=https://www.icis.com/explore/resources/news/2003/09/23/521175/explosion-and-fire-halts-lyocell-output-at-lenzing-s-heiligenkreuz-austria-plant/ |work=ICIS Explore}}</ref> In 2004 Lenzing was producing 40,000 [[ton]]s [''sic'', probably metric tonnes].<ref name=merge/> In 1998, Lenzing and Courtaulds reached a patent dispute settlement.<ref name=merge/>

In 1998, Courtaulds was acquired by competitor [[Akzo Nobel]],<ref name=Europa>{{cite web|url=http://europa.eu/bulletin/en/9806/p103050.htm|title=Bulletin EU 6-1998 (en): 1.3.50 {{!}} Akzo Nobel/Courtaulds |work=Europa|access-date=13 November 2015 |archive-url=https://web.archive.org/web/20080922035918/http://europa.eu/bulletin/en/9806/p103050.htm |archive-date=22 September 2008 |url-status=dead}}</ref> who combined the Tencel division with other fibre divisions under the Accordis banner, then sold them to private equity firm [[CVC Partners]]. In 2000, CVC sold the Tencel division to [[Lenzing AG]], who combined it with their "Lenzing Lyocell" business, but maintained the brand name Tencel.<ref name=merge>{{Cite web |url=http://www.fibersource.com/F-Info/More_News/lenzing-050504.htm |title=Lenzing Acquires TENCEL®, 2004 |access-date=13 January 2010 |archive-url=https://web.archive.org/web/20100323063249/http://www.fibersource.com/f-info/More_News/lenzing-050504.htm |archive-date=23 March 2010 |url-status=dead }}</ref> They took over the plants in Mobile and Grimsby, and by 2015 was the largest Lyocell producer at 130,000 tonnes/year.<ref name=chen/>

==Uses==
[[File:Patagonia, OutDoor 2018, Friedrichshafen (1X7A0346).jpg|thumb|Shirt made from Lyocell]]

It is used in many everyday fabrics. [[Staple (textiles)|Staple fibres]] are used in clothes such as [[denim]], [[Chino cloth|chino]], underwear, casual wear, and towels. Filament fibres, which are generally longer and smoother than staple fibres,{{sfn|Yates|2002|p={{pn|date=April 2025}}}} are used in items that have a silkier appearance such as women's clothing and men's [[dress shirt]]s. Lyocell may be blended with a variety of other fibres such as [[silk]], cotton, rayon, polyester, [[linen]], [[nylon]], and [[wool]]. When mixed with other fibres, the resulting fabric is much stronger and more resistant to wear, tear, and pilling.<ref>Sewport Support Team. (n.d.). What is Lyocell Fabric: Properties, how its made and where. Sewport. https://sewport.com/fabrics-directory/lyocell-fabric</ref> Lyocell also is used in [[conveyor belts]], speciality [[paper]]s, and [[medical dressings]].{{sfn|Kadolph|Langford|2001|p={{pn|date=April 2025}}}}

==Properties==
[[File:Fibrillation of lyocell fibre.png|thumb|Fibrillation of Lyocell may produce a "peach-fuzz" feel.]]

Lyocell shares many properties with other fibres such as [[cotton]], [[linen]], [[silk]], [[ramie]], [[hemp]], and [[viscose rayon]] (to which it is very closely related chemically). Lyocell is 50% more absorbent than cotton, <ref>{{Cite web |url=https://www.theguardian.com/fashion/2019/nov/18/pulp-fabric-everything-you-need-to-know-about-lyocell |title=Pulp fabric: Everything you need to know about lyocell |website=[[TheGuardian.com]] |date=18 November 2019 }}</ref> and has a longer wicking distance compared to modal fabrics of a similar weave.<ref>{{cite journal |last1=Ozdemir |first1=Hakan |title=Permeability and Wicking Properties of Modal and Lyocell Woven Fabrics Used for Clothing |journal=Journal of Engineered Fibers and Fabrics |date=March 2017 |volume=12 |issue=1 |doi=10.1177/155892501701200102 |doi-access=free }}</ref>

Compared to cotton, consumers often say Lyocell fibres feel softer and "airier", due to their better ability to wick moisture. Industry claims of higher resistance to wrinkling are as yet unsupported. Lyocell fabric may be machine washed or dry cleaned. It drapes well and may be dyed many colours, needing slightly less dye than cotton to achieve the same depth of colour. <ref>{{Cite web |url=http://www.fibersource.com/f-tutor/lyocell.htm |title=FiberSource }}</ref><ref name=good/>

==Manufacturing process==
The Lyocell process uses a direct solvent rather than indirect dissolution such as the xanthation-regeneration route in the viscose process. Lyocell fibre is produced from [[dissolving pulp]], which contains [[cellulose]] in high purity with little [[hemicellulose]] and no [[lignin]]. Hardwood logs (such as [[oak]] and [[birch]]{{better source needed|date=May 2024}}<ref name="madehow" />) are chipped into squares about the size of postage stamps. The chips are digested chemically, either with the prehydrolysis-[[kraft process]] or with [[sulfite process]], to remove the [[lignin]] and hemicellulose. The pulp is bleached to remove the remaining traces of lignin, dried into a continuous sheet and rolled onto spools. The pulp has the consistency of thick [[posterboard]] paper and is delivered in rolls weighing some 500&nbsp;lb (230&nbsp;kg).

:[[File:NMO.png|thumb|left|148px|[[N-Methylmorpholine N-oxide|''N''-Methylmorpholine ''N''-oxide]] is a key solvent in the Lyocell process ]]

At the Lyocell mill, rolls of pulp are broken into one-inch squares and dissolved in [[N-Methylmorpholine N-oxide|''N''-methylmorpholine ''N''-oxide]] (NMMO<ref name=brief/>), giving a solution called "dope". The filtered cellulose solution is then pumped through [[Spinneret (polymers)|spinnerets]], devices used with a variety of synthetic fibres. The spinneret is pierced with small holes rather like a shower head; when the solution is forced through it, continuous strands of filament come out. The fibres are drawn in air to align the cellulose molecules, giving the Lyocell fibres its characteristic high strength. The fibres are then immersed into a water bath, where desolvation of the cellulose sets the fibre strands. The bath contains some dilute amine oxide in a steady state concentration. Then the fibres are washed with demineralised water. Next, the Lyocell fibre passes to a drying area, where the water is evaporated from it.

Manufacture then follows the same route as with other kinds of fibres such as viscose. The strands pass to a finishing area, where a lubricant, which may be a soap or silicone or other agents, depending on the future use of the fibre, is applied. This step is a detangler, prior to carding and spinning into yarn. At this stage, the dried, finished fibres are in a form called tow, a large, untwisted bundle of continuous lengths of filament. The bundles of tow are taken to a crimper, a machine that compresses the fibre, giving it texture and bulk. The crimped fibre is then carded by mechanical carders, which perform a combing action to separate and order the strands. The carded strands are then cut and baled for shipment to a fabric mill. The entire manufacturing process, from unrolling the raw cellulose to baling the fibre, takes roughly two hours. After this, the Lyocell may be processed in many ways. It may be spun with another fibre, such as cotton or wool. The resulting yarn can be woven or knitted like any other fabric, and may be given a variety of finishes, from soft and suede-like to silky.{{sfn|Kadolph|Langford|2001|p={{pn|date=April 2025}}}}

The [[amine oxide]] used to dissolve the cellulose and set the fibre after spinning (NMMO) is recycled. Typically,<ref name="madehow">{{Cite web |title=How lyocell is made - material, manufacture, making, used, processing, steps, industry, machine |url=http://www.madehow.com/Volume-5/Lyocell.html |access-date=28 July 2022 |website=www.madehow.com}}</ref> 99 per cent of the amine oxide is recovered.<ref name="good">{{Cite web|date=27 July 2018|title=Material Guide: How Ethical is Tencel?|url=https://goodonyou.eco/how-ethical-is-tencel/|access-date=21 July 2020|website=Good On You|language=en}}</ref> NMMO biodegrades without producing harmful products.<ref name=brief/> Since there is little waste product, this process is relatively eco-friendly, though it is energy-intensive.<ref name="good" />

===Future research===
Lyocell's lack of antibacterial properties limits its uses in the medical field. Due to its biodegradability, low toxicity, and comfort, Lyocell would become a useful material for antibacterial garments. Several approaches have been tested to introduce antibacterial capabilities. Three general approaches have been studied to achieve this: physical blending, chemical reaction, and post-treatment. Physical blending methods introduce antibacterial agents into the spinning dope. In chemical reaction methods, antibacterial additives are crosslinked into the Lyocell fibres and therefore giving antimicrobial properties. In post-treatment methods, antibacterial additives are being deposited on Lyocell fibre surfaces through physical coating, padding, or impregnation processes. Physical blending and post-treatment methods appear to be the most promising for large-scale manufacturing. Careful consideration of cost, preparation time, and antibacterial effectiveness is required to select the best method. Creating successful modification of Lyocell fibres to enhance antibacterial properties would allow to manufacture products for health care (such as lab coats, caps, gowns), hygiene products (scrubs, sanitary napkins), and clothing (socks, underwear).<ref>{{cite journal |last1=Edgar |first1=Kevin J. |last2=Zhang |first2=Huihui |date=December 2020 |title=Antibacterial modification of Lyocell fiber: A review |journal=Carbohydrate Polymers |volume=250 |pages=116932 |doi=10.1016/j.carbpol.2020.116932 |pmid=33049845 }}</ref>

==See also==
* [[Modal (textile)]]

==References==
{{Reflist}}

==Sources==
* {{cite book |last1=Kadolph |first1=Sara J. |last2=Langford |first2=Anna |title=Textiles |date=2001 |publisher=Prentice Hall |isbn=978-0-13-025443-6 }}
* {{cite book |last=Yates |first=Marypaul |date=2002 |title=Fabrics: A Hanbook For Interior Designers And Architects |publisher=W. W. Norton & Company |isbn=978-0-393-73062-3 }}

==Further reading==
* {{cite book |last=Blanc |first=Paul David |title=Fake Silk: The Lethal History of Viscose Rayon |date=2016 |publisher=Yale University Press |isbn=978-0-300-20466-7 }}

{{Fibers}}

[[Category:Cellulose]]
[[Category:Synthetic fibers]]