A report for

LUT BJ02A4050 Biomaterials Design and Application

21.2.2015

Anu Hämäläinen

d0365421

anu.hamala (at) gmail.com

Cellulosic

Textile

Fibres

A review

Anu Hämäläinen

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Contents

1. Introduction ..................................................................................................................................... 2

2. World’s fibre production .................................................................................................................. 2

3. Cellulosics textile fibre technologies ................................................................................................. 4

3.1 Viscose ........................................................................................................................................ 5

3.2 Modal ........................................................................................................................................... 5

3.3 Acetate and triacetate ................................................................................................................. 5

3.4 Lyocell .......................................................................................................................................... 6

3.5 New textile fibre production technologies: Ioncell and Biocelcol ............................................ 6

4. Wood as a raw material for textiles .................................................................................................. 8

5. Life cycle assessment of textiles ....................................................................................................... 8

6. Conclusions ...................................................................................................................................... 9

Abbreviations ....................................................................................................................................10

Sources .............................................................................................................................................10

Annexes ..............................................................................................................................................11

Annex 1 World Man-Made Fibres Production ..............................................................................11

Annex 2 Viscose production process scheme ...............................................................................12

Annex 3 Lyocell production process scheme .................................................................................13

Picture on the cover: Textiles made of Lyocell®

http://www.cirfs.org/ManmadeFibres/Fibrerange/Lyocell.aspx cited 17 Feb 2015

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1. Introduction

This review is written as a report for the LUT course LUT BJ02A4050 Biomaterials Design and

Application. Taking into account the writer’s long career and experience in pulp and paper industry, it

aims to familiarize the writer with wood-based textile fibres from the product and business development

point of view, and gives less attention to the recent research activities of textile fibres.

2. World’s fibre production

The first artificial fibers were introduced by the French scientists Hilaire de Chardonnet at the World

Exhibition in Paris in 1889. The material, consisting of nitrocellulose, was extremely flammable and thus

could not reach any importance in the textile industry. In 1892 the first viscose process patent was

granted to the British scientists, Charles Frederick Cross, Edward John Bevan and Clayton Beadle. The

first commercial viscose plant was built by the British company Courtaulds Fibers in 1905, followed by

industrial plants in Central Europe and USA. Although the use of toxic carbon disulfide posed a

significant health and safety risk, the viscose technology succeeded against other fiber production

technologies mainly because of the unique fiber quality and the broad variety of different fiber types

ranging from standard fibers to cotton-like modal and polynosic fibers and very strong technical fibers

such as tyre cord.

The viscose production reached 3.000 tons in 1930. The viscose boom, however, started in the 1930s

with many new installations, triggered by the continuously improved technology and the starting

preparations for war in Germany to become independent on cotton imports. The global viscose

production reached almost 600.000 t in 1940 during World War II. /1/

Parallel to the upturn of viscose fibers, nylon, the first synthetic fiber, was invented by Wallace Carothers

from DuPont. Its production started in 1935. The thermoplastic polymer was first used as a material for

women's stocking, parachutes, ropes and the like before it entered the textile market. Although the

viscose fiber market kept on growing until the late 1970s, the amount of synthetic fibers, complemented

by polyester, polypropylene and acrylic fibers, developed significantly faster. The global production of

synthetic fibers equaled the viscose fiber production already in the late 1960s. The synthetic fiber

production continued to grow by 510% on average per year, while the viscose fibers peaked end of the

1970s before it lost more than 40% of its production in the beginning of 2000. The consumption of

natural fibers, consisting of cotton (78-83%), wool (4%), flax, hemp, jute and ramie (altogether 13%) and

others (silk, abaca, algave, coir, kapok, sisal and silk, altogether 5%), increased by about 65% since

1965. /1/

According to the European Man-made Fibres Association CIFRS, world’s annual textile fibre production

reached about 90 million tons in year 2013, see figure 1. Natural fibres, mainly cotton and wool,

accounted for 30 % of the total, and man-made fibres for 70 %. Man-made fibres include two main sub-

groups: synthetics and cellulosics. The share of man-made fibres has increased since year 2000; while

the average annual fibre production growth was 4,2 % in 2000-2013, the growth of synthetic fibres was

5,2 % and that of cellulosic fibres 5,9 %. In 2011 – 2013 the cellulosic fibre production increase was

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over 10 % per annum. The statistics of world’s annual fibre production in years 1900 – 2013 is

presented in the Annex 1. /2/

Figure 1. World’s textile fibre production in year 2000 and 2013.

Data source: European Man-made Fibres Association CIFRS

The total annual textile fibre production in 2013 was about half of the annual wood pulp production,

figure 2. The dissolving pulp production, the major raw material for cellulosic textile fibres, has doubled

since year 2000, and reached about 5,6 million tons in year 2013.

Figure 2. World’s annual pulp production 1998 - 2013, million tons per annum.

According to CIFRS, the man-made fibres’ principal end-use is in clothing, carpets, household textiles

and a wide range of technical products - tyres, conveyor belts, fillings for sleeping bags and cold-weather

clothing, filters for improving the quality of air and water in the environment, fire-resistant materials,

reinforcement in composites used for advanced aircraft production. Fibres are precisely engineered to

give the right combination of qualities required for the end-use in question: appearance, handle, strength,

durability, stretch, stability, warmth, protection, easy care, breathability, moisture absorption and value

for money, for example. In many cases, they are used in blends with natural fibres such as cotton and

wool.

Raw cotton35 %

Raw wool3 %

Synthetics total57 %

Cellulosics total5 %

2000 World's textile fibre production 53 Mtons

Raw cotton29 %

Raw wool1 %

Synthetics total64 %

Cellulosics total6 %

2013 World's textile fibre production 90 Mtons

0

20

40

60

80

100

120

140

160

180

200

Chemical wood pulp

Mechanical wood pulp

Dissolving pulp

Other fibre pulp

Wood pulp total

World'sAnnual Pulp ProductionMillion Tons

Source: FAOSTAT

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Man-made fibres come in two main forms: continuous filament, used for weaving, knitting or carpet

production; and staple, discontinuous lengths of fibre which can be spun into yarn or incorporated in

unspun uses such as fillings or nonwovens.

Major producers of viscose fibres are Aditya Birla Group/IN, Lenzing/AT, Kelheim-fibres/DE, Tanshan

SanYou/CN, Aoyang Technology/CN, Fulida Group/CN, Chengdu Huaming/CN, Sateri (Jiangxi)

Chemical Fibre/CN, Shandong Helon/CN, Silver Hawk/CN, Xinxiang Bailu/CN, Shandong Bohi/CN,

Xiangsheng/CN, Zhejiang YueLong (Somet Fiber)/CN, Jiangsu Sanfangxiang/CN, Nanjing Chemical

Fiber/CN, Manasi Shunqun, Jiujiang Hengsheng Chemical Fiber/CN, Jilin Chemical Fiber/CN and Hubei

Golden Ring/CN. /3, country codes added by the writer/

3. Cellulosics textile fibre technologies

The International Bureau for Standardisation of Man-made Fibres BISFA definition of generic fibre

names is presented in Figure 3. /4/

Figure 3. Generic fibre names with their codes. Copyright by BISFA 2011. /4/

Regulation (EU) No. 1007/2011 of the European Parliament and the Council of 27 September 2011 on

textile fibre names and related labelling and marking of the fibre composition of textile products (Official

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Journal L 272, 18.10.2011, p.1) describes conditions and rules for the labelling of textile products /5/.

The regulation defines the same cellulose based fibres as BISFA.

3.1 Viscose

There are several fibres made from the naturally occurring polymer cellulose, which is present in all

plants. Mostly cellulose from wood is used to produce the fibres but sometimes cellulose from short

cotton fibres, called linters, is the source. By far the most common cellulosic fibre is viscose fibre. /2/

Viscose fibres are made from wood pulp which is ground and reacted with caustic soda. After an

ageing period, the ripening process during which depolymerisation occurs, carbon disulphide is added.

This forms a viscous yellow solution cellulose xanthate, when dissolved in caustic soda. The solution is

pumped through a spinneret, which may contain thousands of holes, into a dilute sulphuric acid bath

where the cellulose is regenerated as fine filaments as the xanthate decomposes. The process scheme

is presented in the Annex 2. /2/

Viscose fibres, like cotton, have a high moisture regain. It dyes easily, it does not shrink when heated,

and it is biodegradable. It is used in many apparel end-uses, often blended with other fibres, and in

hygienic disposables where its high absorbency is of great advantage. In filament yarn form it is

excellent material for linings. It is used very little in home furnishing fabrics but in the industrial field,

because of its thermal stability, a high modulus version is still the main product used in Europe to

reinforce high speed tyres. /2/

3.2 Modal

Modal fibres belong to the second generation of viscose fibres and are high wet modulus fibres made

by a modified viscose process with a higher degree of polymerisation and modified precipitating baths.

This leads to fibres with improved properties such as better wear, higher dry and wet strengths and

better dimensional stability. /2/

Modal fibres are smooth and soft, making it very suitable for body conscious clothing, like intimate

apparel. Modal fibres are highly absorbent and quickly soak up water so that it still feels dry even when

holding a considerable amount of water. /2/

3.3 Acetate and triacetate

The acetate fibres are made from cellulose acetate. The difference between acetate and triacetate fibres

lies in the number of the cellulose hydroxyl groups that are acetylated. For acetate fibres the number lies

between 75% and 92%, for triacetate fibres it is more than 92%. /2/

Wood pulp is dissolved by acetic acid and then converted to cellulose acetate using acetic anhydride

which is then dissolved in acetone. The resulting viscous solution is pumped through spinnerets into

warm air to form filaments. The acetone evaporates and is recovered. The filaments are then wound up

as filament yarns or collected as a tow. /2/

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Acetate and triacetate fibres’ major difference to viscose is their thermoplasticy. They are generally dyed

using disperse dyes, absorb little water and can be textured. Although the dry strength of the two types

are similar, triacetate has a higher wet strength. It also has a high melting point, 300o C, compared with

250o C for diacetate. Main end-uses for the filament yarns are linings and dresswear. There is very little

staple fibre made from these fibres but acetate tow is the major product used for cigarette filters. /2/

3.4 Lyocell

The increasing environmental awareness has initiated the development of new technologies to replace

the tradional visocose process using the highly poisonous carbon disulphide as a solvent. A new

generation of cellulosic appeared in the market in December 1992 when a commercial plant in the USA

started to make a lyocell staple fibre. Subsequently, two European production plants have opened.

Lyocell fibres are made in solvent spinning process, see Annex 3. The cellulose is directly dissolved in

the solvent N-methylmorpholine n-oxide (NMMO) containing water. The solution is then filtered and spun

through spinnerets to make the filaments, which are spun into water. The NMMO solvent is recovered

from this aqueous solution and reused./2/

The lyocell fibres, like other cellulosics, are moisture absorbent and biodegradable. They have a dry

strength higher than other cellulosics and approaching that of polyester. They also retain 85% of their

strength when wet. Under certain conditions lyocell fibres fibrillate which enables fabrics to be developed

with interesting aesthetics. Non- fibrillating versions are also available. Lyocell fibres are mostly used for

apparel fabrics, especially outerwear, but it has been shown that, due to the fibrillating property some

very interesting nonwoven fabrics can be made as well./2/

Currently, the NMMO-based Lyocell technology is completely covered by Lenzing AG and the company's

policy prevents that this technology can be licensed by other companies. /1/

3.5 New textile fibre production technologies: Ioncell and Biocelcol

NMMO as a cellulose solvent has some intrinsic shortcomings such as its chemical and thermal

instability, causing runaway reactions. The extension of the Lyocell spinning technology to direct

cellulose solvents of high thermal and chemical stability is very attractive from a safety, environmental

and economic point of view. /1/

After the rediscovery of ionic liquids (ILs) as powerful cellulose solvents in 2002 by Rogers and his co-

workers new research efforts were initiated to design task specific ILs aiming at the substitution of

NMMO as the only commercial direct cellulose solvent. The ionic liquids, which proved to be effective

cellulose solvents and thus have been used for the preparation of spinning dopes, were all imidazolium-

based. It was shown that the direct dissolution of cellulose is more easily controlled, the process is

inherently safer, and fibers with properties equal to those produced from NMMO solution were obtained.

However, the imidazolium-based ionic liquids have shown to be not inert towards cellulose. Depending

on the substituent’s on the imidazolium ring and the chemical nature of the anion, cellulose undergoes

severe degradation, especially at higher temperatures (>90°C) which is controlled by adding

stabilizers./1, 6/

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A group of researchers at Helsinki University and Aalto University have developed a novel cellulose

spinning solvent consisting of a superbase / acid ion pair. The optimum rheological properties of the

cellulose dope for spinning are attained at moderate temperatures at which uncontrolled cellulose

degradation can be avoided. The mechanical properties of the resulting fibers are outstanding and reach

the highest level known for commercial regenerated cellulose fibers (tensile strength 700 - 870 MPa,

elastic modulus 25 - 35 GPa). Figure 4 underlines the superior mechanical properties of the novel Ioncell

fiber. /1/ An amount of about 1 kg of Ioncell fibres from Finnish brich kraft pulp was produced at lab

scale in several institutes in Finland and Sweden. The dress shown in Figure 5 was designed by Tuula

Pöyhönen from Marimekko® and presented on the occasion of the fashion show in Helsinki Central

Railway Station's ticket hall on March 13, 2014. /1/

cccccc

Figure 4. Stress-strain curve of the Ioncell-fiber and Figure 5. A dress made of Ioncell fibres

of commercial regenerated cellulose fibers. (Courtesy to Marimekko®).

A group of researchers at Tampere University of Technology have published an enzyme treatment

based process to produce textile fibres called Biocelsol. A comparison of viscose process and Biocelsol

process is presented in Figure 6. /7/

Figure 6. Viscose process versus enzyme assisted Biocelsol process. /7/

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4. Wood as a raw material for textiles

In average, the stem wood fibres’ dry weight is composed of 95 % of high molecular mass substances:

lignin (25 % of the grand total) and polysaccharides: cellulose (40%), hemicelluloses (30 %) and minor

amount of others, as well as 5 % low molecular mass substances, such as extractives 3,5 % and

inorganic material 0,5 %. The latter consists of several elements, such as potassium, calcium,

magnesium, phosphor, fluorides, sodium, silicon, sulphur, manganese, iron, zinc and barium. /6/

From the textile manufacturing point of view, only cellulose is of interest, and the other components of

the wood fibres should be removed during the wood pulp process. Both sulphite and kraft pulp process

are suitable for textile fibre/dissolving pulp production; typical properties of dissolving pulp are given in

the table 2./8/

Table 2. Dissolving pulp grades and typical properties/8, p. 1040/

Sulfite pulps Pre-

hydrolysis

kraft pulp

Standard Super I Super II

Alfa cellulose content, % 91 92 93 95…97,5

Alkali resistance R18 % (ISO R 699) 93 94 95,2 96…99

Extractives content, DCM % (ISO 624) 0,10…0,35 0,01…0,1

Ash content % (ISO R 1762 0,03…0,10 0,03…0,06

Viscocity, cP 18…22 10…17

Viscocity, dm3/kg (SCAN C15/62) 540…595 380…520

Brightness, % (ISO R 2470) 90…95 86…92

Dissolving pulp has high alpha cellulose content in comparison to chemical pulps aimed for paper and

board production, which contain hemicelluloses, too. /6,8/ The degree of polymerization (DP) in the

native wood cellulose is about 10.000 (cotton’s DP is about 15.000); that of typical paper and board

chemical pulp’s DP is in the range of 1000-2000, and that of dissolving pulp is in the range of 500./6/

During the recent years, traditional paper and board pulp producers have started to offer their products

to textile industry, e.g. Stora Enso’ Enocell mill has rapidly created a turnover of about 150 M€ by year

2013 with pulp sales to viscose manufacturers. /9/

Several wood species are suitable for textile fiber pulp, such as spruce, birch and eucalyptus /7/. Also

other plants, such as bamboo, have successfully been introduced as raw material to textile fibres /10/.

5. Life cycle assessment of textiles

During the past few decades various consumer products’ life cycles have been assessed. Textile fibres

are no exception: e.g. Greenpeace has raised serious concerns about the high water and pesticide

consumption of cotton crops /11/. Chapman /12/ points out that the Life cycle assessments (LCA) of

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textile fibres are difficult to compare due to limited consistency and number of the studies. Typically, the

textile fibre LCA has been limited to ‘cradle-to-gate, i.e. covering only the harvesting and production of

textiles, and reporting only primary energy consumption or ecotoxicity. He points out that the consumer

phase has a remarkable environmental impact: the method and frequency of washing clothes makes a

major input into ‘cradle-to-grave’ footprint of a garment.

Research is on-going to improve the properties of textile fibres. As examples Fahmy & al. /13/ have

studied the impact of Tinosan CEL, silver and titan dioxide treatment on viscose fibres ‘Easy care’

finishing. In their report they also mention ultra violet light and number of other chemicals as possible

finishing treatment methods. El-Gabry & al. /14/ have studied silicon dioxide nanoparticles treatment for

improving the antibacterial and coloration properties of viscose and polyester fabrics. However, the

reports do not indicate the clothing LCA impact of the tested chemicals.

6. Conclusions

As the population and their income level is growing in the world, it can be expected that the consumption

of textile fibres will increase in the future. Wood pulp is both economically and environmentally a

feasible raw material source for textile fibres. Some of the kraft pulp capacity has already been

converted from paper and board pulp grades to dissolving/textile fibre grades.

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Abbreviations

AT Austria

CN China

DE Germany

DP Degree of polymerisation

IL Ionic liquids

IN India

LCA Life cycle assessment

LUT Lappeenranta University of Technology

NMMO N-methylmorpholine n-oxide (solvent)

Sources

1. Sixta, H. 2014. IONCELL-F, a novel Man-made Cellulosic Fiber. Available at: http://puu.aalto.fi/en/midcom-

serveattachmentguid-1e44f95c44218204f9511e4a12b01d1437b57775777/regeneroidut_kuidut.pdf

2. CIRFS web site: http://www.cirfs.org/ManmadeFibres/Aboutmanmadefibres.aspx Cited on 17 Feb 2015

3. Deep Research Reports. 2014. Global and China Viscose Fiber Industry Report 2013-2016. Abstract

available at http://www.reportlinker.com/p0797120-summary/Global-and-China-Viscose-Fiber-Industry-

Report.html Cited on 5 Feb 2015

4. BISFA web site: http://www.bisfa.org/GENERICFIBRENAMES/Existingnames.aspx Cited on 17 Feb 2015

5. Regulation (EU) No. 1007/2011 of the European Parliament and the Council. Available at:

http://ec.europa.eu/enterprise/sectors/textiles/single-market/reg-1007-1011/index_en.htm

6. Alen, R. (ed.) 2011. Biorefining of Forest resources. Papermaking Science and Technology, Book 20.

Paper Engineers’ Association/Paperi ja Puu Oy. 381 p.

7. Nousiainen, P. & al. 2011. Enzymatic modification of pulp cellulose to regenerated fibers and films via

aqueous alkaline solutions. Seminar presentation in 7th International Conference on Polymer and

Textile Biotechnology, March 3-5 2011, Milan, Italy.

8. Kekki, R. & Leppäkoski, H. 1983. Liuko- ja erikoissellut. SPIY oppi- ja käsikirja Osa II, Puumassan

valmistus. Toim. N-E. Virkola. 1106 p.

9. Harlin, A. Oral communication. Forest Bio Economy Rosdshow, Imatra, 18 September 2013.

10. Tausif, M. & al. 2015. A comparative study of mechanical and comfort properties of bamboo viscose as

an eco-friendly alternative to conventional cotton fibre in polyester blended knitted fabrics. Journal of

Cleaner Production 89 (2015), pages 110 – 115. Available at www.elsevier.com

11. Tirado, R. 2010. Picking cotton - The choice between organic and genetically-engineered cotton for

farmers in South India. Available at www.greenpeace.org, cited on 15 January 2015.

12. Chapman, A. 2010. Mistra Future Fashion – Review of Life Cycle Assessments of Clothing. The

Foundation for Strategic Envinronmental Research. www.mistra.org. Cited on 15 February 2015.

13. Fahmy, H.M. & al. 2013. Enhancing some functional properties of viscose fabric. Carbohydrate

Polymers 92(2013), pages 1539 – 1545. Available at www.elsevier.com

14. El-Gabry, L.K. & al. 2013. Surface functionalizations of viscose and polyester fabrics towards

antibacterial and coloration properties. Carbohydrate Polymers 92(2013), pages 353 – 359. Available at

www.elsevier.com

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Annexes

Annex 1 World Man-Made Fibres Production

http://www.cirfs.org/KeyStatistics/WorldManMadeFibresProduction.aspx cited 17 Feb 2015

12

Annex 2 Viscose production process scheme

http://www.cirfs.org/ManmadeFibres/Fibrerange/Viscose.aspx cited 17 Feb 2015

13

Annex 3 Lyocell production process scheme

http://www.cirfs.org/ManmadeFibres/Fibrerange/Lyocell.aspx cited 17 February 2015