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Textile Effects INTRODUCTION TO PRETREATMENT
52

Pre Treatment

Nov 18, 2014

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Page 1: Pre Treatment

Textile Effects

INTRODUCTION

TO

PRETREATMENT

Page 2: Pre Treatment

Textile Effects

High and even hydrophilicity / rewettability Good desizing effect High degree of whiteness Removal of seed husks Removal of foreign substances from the fibers Lowest possible fiber damage High color yield Neutral pH Levelness of the effects

Aim of the pretreatment

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Textile Effects

Fibres (natural or synthetic materials)

Structure / Makeup / End use (Woven goods, knit goods, yarn ….)

Machine (Continuous, Discontinuous, Semi-continuous)

Chemicals (Wetting-/Washing agents, Complexing agents ….)

Pretreatment processes (Desizing, Scouring, Bleaching ….)

Pretreatment is dependent on

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Textile Effects

POLYAMIDEPOLYAMIDE

VISCOSEVISCOSEWOOLWOOL

SILKSILKLINENLINEN

COTTONCOTTON

POLYESTERPOLYESTERACRYLICACRYLIC

Fibres

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Textile Effects

m in eral fi ber

silk

th ickan im al h airs

w oo l andfi ne an im als h airs

w oo l and h airs

an im al fi ber

fruit fiber leaf fiber

h ard m anson ite b ast fi ber p lan t hair

veg etab le fi ber

n atural fi ber

Asbestosa.o.

SilkTussah

Goat-hairBeef-hairHorse-hair

Wool (sheep’s wool)- Alpaca wool- Lama woolCamel-woolRabbit-hair- Angora woolGoat-hair- Mohair- Kashmir hair- Tibet hair

Coco SisalManila

FlaxHempJuteSunnKenafRamie

CottonKapok

Fibres: Classification of natural fibers

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Textile Effects

Po lyadd ition s-fi ber

Po lym erisation s-fi ber

Po lycon d en sation s-fi ber

ch em ical fib er w ithsynth etic p o lym er

T iereiw eiss-fasern

an im ald erivation

veg etab lep rotein fi ber

g umfi ber

p ap erfi ber

cellu losicfi ber

veg etab led erivation

ch em ical fib er w ithn atural p o lym er

ch em ical fib er

PolyesterPolyamidePolyester-Ether

GumPolyamidePolyacrylPolypropylenePolyethyleneElastodienModal acrylVinylPolystyrolPolychloride

PolyurethaneElasthan

Casein

ZeinArdein

Spinning-paperCellulon

ViscoseCuproAcetateTriacetateModal

Fibres: Classification of synthetics fibers

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Textile Effects

Discontinuoussystems

Semi continuoussystems

Continuoussystems

Pad steam,L/J/U box,

Immersion system,

Pad batch,Pad roll

Jigger,Jet,

Winch and other

Machines

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Textile Effects

Machines: Discontinuous system

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Textile Effects

Machines: Semi-continuous system

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Textile Effects

Machines: Continuous system

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Textile Effects

Ca Mg Fe CuMn

Brazil - Paranah 2700 1100 250 630

- San Paulo 940 760 70 <1 6

Peru 700 440 15 <1<1

USA - Texas 810 365 75<1 <1

- California 600 540 40 <1<1

Russia, Turkey,India, Pakistan 1300 570 110 3

6

Egypt 640 450 11 <1<1

mg/kg (ppm)

Ca Mg Fe CuMn

Brazil - Paranah 2700 1100 250 630

- San Paulo 940 760 70 <1 6

Peru 700 440 15 <1<1

USA - Texas 810 365 75<1 <1

- California 600 540 40 <1<1

Russia, Turkey,India, Pakistan 1300 570 110 3

6

Egypt 640 450 11 <1<1

mg/kg (ppm)

Analyses of different cotton qualities

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Textile Effects

Surfactants (Wetting- and washing

agent)

Complexing agent / Cracking agent

Processor / Stabilizer

Defoamer

Enzyme

Chemicals

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Textile Effects

The classical steps of pretreatment: cotton

woven goods

Singeing Burning down of the protruding fibers

Desizing Removal of sizing agents

Scouring/ Improvement in hydrophilicityAlkaline Cracking Cracking of seed husks

Removal of foreign substances

Acid Cracking Complexing/dispersing/cracking of

alkaline earth metals and heavy metals

Bleaching Destruction of colored substances

Removal of seed husks

Mercerizing/ Modification of the inner surfaceCaustifying

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Textile Effects

To obtain a smooth,clean fabric surface (Napless / pile less finishing)Parameter :

• fabric speed (up to 250 m/min)• flame intensity (gas-/air-mixture; 1200-1300°C)• burner distance / burner position

receipt of goods brushing singeing tension beater impregnation batching

Singeing: Parex-Mather

Singeing

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Textile Effects

Starch is a polysacharide and consist of:

• 14 - 27% amylose (water soluble)• 73 -86% amylopectin (water insoluble)

starch- amylosecontent in the starch

potato 20% 23%maniok/tapioka 25% 18%sago 27% 26%wheat/maize 60% 25%rice 75% 19%

Natural sizes Natural sizes (water insoluble)(water insoluble) Synthetic sizes Synthetic sizes (water soluble)(water soluble)

Polyvinyl alcohol size (PVA)Polyacrylate size (PAC)Polyester size (PES)

Carboxymethyl cellulose (CMC)

Desizing: Sizes

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Textile Effects

DESIZING

Starches

Starches in combination withwater soluble sizes

Water soluble sizes Starches

Starches in combination withwater soluble sizes

ENZYMATIC

OXIDATIVE

SURFACTANT

Desizing: Starch size

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Textile Effects

Advantages of enzymatic desizing

• No fibre damage

• No use of aggressive chemicals

• A lot of process possibilities

• High biological degradability

Disadvantages of enzymatic desizing

• Low additional cleaning and cracking effect

• Low effects on certain starches, e.g. tapioca starches

• Effects can be reduced by certain size additives and other

impurities

Enzymatic Desizing - Advantages / Disadvantages

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Textile Effects

Surfactants are water-soluble,

surface active agents

Surfactants are used in textile applications as,

Detergent Wetting agent Emulsifier Softener Lubricant

What are surfactants ?

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Textile Effects

air

waterhydrophilic

hydrophobic

material

oil, wax or soil

Detergency / Washing power

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Textile Effects

Boiling out is the treatment of cellulose under strong alkaline conditions.

Raw cotton contains a great number of foreign substances such as hemicelluloses, proteins, lignins, pectins, fats, waxes, natural dyes and seed husks. These are partly water-soluble, partly only removable by an alkaline process. In some cases an acid treatment is necessary.

Seed husks and cotton waxes can only be eliminated by longer alkaline boiling or kier boiling. This process is important to improve the hydrophilicity (a must for continuous dyeing and printing). A boiling process is also useful to reduce the danger of a catalytic damage in a subsequent peroxide bleach.

Scouring / Alkaline Cracking

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Textile Effects

Bleaching means, to destroy the natural dyestuff in the fibre.

There are two chemically different bleaching processes:

Oxidative bleaching with hydrogen peroxide, sodium hypochlorite, sodium chlorite or peracetic acid Reductive bleaching with stabilized hydrosulphite preparations and sulphoxylates.

The choice of chemicals depends on the required degree of whiteness, on technological and ecological aspects, on the machinery and on economic aspects.

Overdosing of the bleaching chemicals, insufficient temperature regulation, too long bleaching times, existence of catalysts, insufficient stabilizing, etc. may lead to damaging of fibers.

Bleaching

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Textile Effects

Bleaching agents, e.g. hydrogen peroxide, are “stabilized” during manufacture. In bleach liquors which contain hydrogen peroxide, bleaching only occurs after activation, e.g. by the addition of alkali or/and by increased temperature.

This bleaching activity must be “regulated” to prevent rapid, spontaneous decomposition of the bleach and to minimize damage to the fibre, to avoid waste of bleaching chemicals as well as undesirable side reactions.

This process of regulation or control is also called as stabilization.

Processor / Stabilizer

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Textile Effects

Tinoclarite CBB/G-I

PROCESSOR

INHIBITIONof

precipitations

ENCAPSULATIONand INACTIVATION

of catalysts /heavy metal ions

STABILITY in hot oxidizing

and alkaline bath

DISPERSINGof impurities

ACTIVATION andREGULATION of

bleachingactive peroxide

THRESHOLD EFFECTCPS principle

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Textile Effects

Peroxide Killing

The leftover peroxide can cause serious problems in further reactive dyeing

The depth of certain dyes can be lost up to 40%

Turquoise, blues and reds are especially sensitive to peroxide

For peroxide killing either a reductive base product or a catalase enzyme based product can be used.

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Textile Effects

Influence of peroxide on reactive dyeing

With Invatex PC Without Invatex PC

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Textile Effects

Merckoquant® 1.10011.

Peroxide - Testanalytical test strips

O2 2-

MERCK 0 0.5 2 5 10

25mg/l H2O2

Residual peroxidein bath or on materialcan be tested withMerckoquant® test strips

no residual peroxidein bath

30 mg/l H2O2

in bath

5 mg/l H2O2

in bath

Rel. Depth 100 %

Rel. Depth 89 % Rel. Depth 76 %

Rel. Depth 100 %

WithoutCiba® TINOZYM® CAT

WithCiba® TINOZYM® CAT

Rel. Depth 100 %

Influence of peroxide on reactive dyes

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Textile Effects

Bleaching agent: Derivate of sulphurous acids

sodium di-thionite (Na2S2O4)

stab. sodium di-thionitesodium bi-sulfite

Usually stab. sodium di-thionite (e.g. Ciba® CLARIT® PS) is used Application only efficient as pre- or subsequent bleach Low importance for cellulose fibers Use for PA and wool No full white possible

Reductive bleach

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Textile Effects

Caustic concentration 270 - 330 g/l NaOH 100% (28-32 °Bé)Caustic temperature 15 - 20 °C (hot mercerization 60 - 90 °C)Reaction time 45 - 60 sec. (hot: shorter time)

Tension against shrinkageStabilizing up to about 50 g/l NaOH 100%Mercerizing wetting agent for quick and even wettingPretreatment raw, desized, boiled off, bleached

Mercerizing

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Textile Effects

Mercerizing Effects

Increase in colour depth: By modification of the inner fibre surface, the number of absorption places for the dye uptake is increased. Depending on the class and type of dyestuff savings of up to 40 % are possible.

Covering immature and dead cotton:Fibres which died off before maturity, so-called dead cotton, as well as immature cotton which has been picked too early, form small knots during the spinning process. These knots are differently dyed or not dyed at all in the dyeing process. Mercerizing and a suitable selection of dyestuff can level out these differences.

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Textile Effects

Mercerizing Effects

Dimensional Stability:The latent tensions in the fabric are eliminated. During the washing process after mercerization new hydrogen bonds are formed, which "set" the fabric. An optimal dimensional stability of the goods can only be obtained, if the alkali concentration in the fabric is decreased below 50 g/kg NaOH 100 %, before leaving the stabilizing zone.

Increase in tensile strength:Due to the transformed orientation of the cellulose chains in the cotton fibres their mechanical properties are changed. This leads to an improvement of the tensile strength. In the case of yarn mercerization the tensile strength may increase up to 40 %.

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Textile Effects

Degree of desizing Water soluble / Residual fat content Hydrophilicity / rewetting effect Ca-, Mg-, Fe-content Degree of whiteness Remove of seed husk DP-value, fiber damage value pH value on the fabric Mercerizing effect

Assessment of the pretreatment effects: General

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Textile Effects

Target: Assessment of the degradation degree of starch size

Procedure: Put fabric sample in iodine solution for about 1 min, short

washing out with cold water, dap with filter paper and

compare immediately with violet scale.

TEGEWA-Violet scale

Assessment of the pretreatment effects: Desizing

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Textile Effects

Water extract

(2x20 min. after petrol

ether extract)

grey fabric 6 - 10 %

good desized < 0.7 %

moderate desized 0.7 - 0.9 %

Water extract

(2x20 min. after petrol

ether extract)

grey fabric 6 - 10 %

good desized < 0.7 %

moderate desized 0.7 - 0.9 % Reference for 100% cotton

Assessment of the pretreatment effects: Water soluble

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Textile Effects

Assessment of the pretreatment effects: Residual fats

Petrol ether

extraction (3

h extraction in soxhlet)

grey fabric 0.8 - 1.2 %

good scouring/bleaching < 0.4 %

moderate scouring/bleaching 0.4 - 0.6 %

Petrol ether

extraction (3

h extraction in soxhlet)

grey fabric 0.8 - 1.2 %

good scouring/bleaching < 0.4 %

moderate scouring/bleaching 0.4 - 0.6 %

Reference for 100% cotton

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Textile Effects

Several methods: TEGEWA-drop testWicking-test“modified wicking-test”

“modified wicking-test” (measurement of the capillary

rise)

time goodness of the hydrophilicity(sec/cm)

- 3 extremely high3 - 5 very good5 - 8 good, acceptable8 - process to be examined

“modified wicking-test” (measurement of the capillary

rise)

time goodness of the hydrophilicity(sec/cm)

- 3 extremely high3 - 5 very good5 - 8 good, acceptable8 - process to be examined

Reference for 100% cotton

Assessment of the pretreatment effects: Hydrophilicity

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Textile Effects

Assessment of the pretreatment effects: Whiteness

Whiteness is a relative term , measured with the help of an instrument known as – SPECTROPHOTOMETER

The instrument helps to measure the reflectance data of the substrate ( without color) and using this data in formulas coverts it into various whiteness readings such as :

GanzCIEStensbyBergerISO/Tappi .. etc

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Textile Effects

Assessment of the pretreatment effects: pH value

The pH value of textile material is determined by the extraction into a neutral medium – 0.1M KCl and then checking on the pH meter .

Alternately the pH on textiles can also be checked by dropping a drop of universal indicator & immediately matching the color obtained with the standard scale .

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Textile Effects

Assessment of the pretreatment effects: Iron content

The iron content on textiles can be determined qualitative by spotting with nitric acid + pottasium thiocyanate .

The presence of iron will be indicated by the appearance of a red color. The higher the intensity of the the coloration more is the amount of iron present.

calcium / iron

magnesium

grey 600 - 2500 ppm 10 - 100 ppm

good pretreatment < 300 ppm < 10 ppm

calcium / iron

magnesium

grey 600 - 2500 ppm 10 - 100 ppm

good pretreatment < 300 ppm < 10 ppm

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Textile Effects

Assessment of the pretreatment effects: Residual peroxide

The residual peroxide on the textile material can be evaluated by spotting with 0.1M Titanum Chloride . The orange coloration in presence of hydrogen peroxide is the matched with the T scale .

The reading of which will immediately give approximately the

mg of H2O2/ kg of fabric.

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Textile Effects

Relaxation

Heat-setting

Scouring / Bleaching

Dyeing / Printing / Finishing / Whitening

Typical process route for Typical process route for

ElastaneElastane

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Textile Effects

Typical process route for LyocellTypical process route for Lyocell

Woven goodsWoven goods

Singeingwide

Desizingwide

+/- Bleachingwide

+/- Singeingwide

Fibrillationrope

Defibrillationrope

Dyeingrope / wide

Finishingrope / wide

T-I-O Processwide

+/- Caustifyingwide

Knit goodsKnit goods

Pre-washrope

+/- Bleachingrope

Fibrillationrope

Defibrillationrope

Dyeingrope / wide

Finishingrope / wide

+/- Defibrillation

rope

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Textile Effects

Cotton Linen/flax

cellulose 90 – 95 % 60 – 65 %

pectines/hemicelluloses 1 – 5 % ~ 20 %

lignins - ~ 3 %

waxes ~ 0.6 % ~ 1 %

watersoluble parts ~ 2.5 % ~ 12 %

With cellulose representing more than 90% of the total fiber composition, cotton is a relatively pure raw product in contrast to linen, which contains only around 60% cellulose. Many more impurities need to be removed from linen.

Linen / flaxAdjacent substances

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Textile Effects

Objectives

Removal of:- sizes- incrustations- alkaline earth and heavy

metal ions High degree of whiteness Good hydrophilicity High fiber protection Reproducibility well-balanced cost-benefit ratio Consideration of environmental

aspects

Objectives

Removal of:- sizes- incrustations- alkaline earth and heavy

metal ions High degree of whiteness Good hydrophilicity High fiber protection Reproducibility well-balanced cost-benefit ratio Consideration of environmental

aspects

Possible pretreatment steps

Enzymatic Desizing/Cracking

Alkaline Cracking Oxidative Cracking Acid Cracking Peroxide Bleach (+/-

silicate) MEGA Bleach Hypochlorite/Chlorite

Bleach Mercerizing

Ammonia treatment

Possible pretreatment steps

Enzymatic Desizing/Cracking

Alkaline Cracking Oxidative Cracking Acid Cracking Peroxide Bleach (+/-

silicate) MEGA Bleach Hypochlorite/Chlorite

Bleach Mercerizing

Ammonia treatment

Linen / flaxObjectives / Pretreatment steps

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Textile Effects

Soft handle Harsh handle (e.g. dress goods /drapery) (e.g. table cloth)

1 – 2oxidative bleaches

2 – 3oxidative bleaches

2 – 4oxidative bleaches

treatment with NaOH

+ Cracking Agent

treatment with soda ash

+ Cracking Agent

Pretreatment processes for linen / flax

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Textile Effects

grey material

Acid Cracking + Peroxide Bleach whiteness Berger 30

Alkaline Cracking + Peroxide Bleachwhiteness Berger 47

Peroxide Bleach + Peroxide Bleach whiteness Berger 53

Acid Cracking + Chlorite Bleach whiteness Berger 73

+ Peroxide Bleach

grey material

Acid Cracking + Peroxide Bleach whiteness Berger 30

Alkaline Cracking + Peroxide Bleachwhiteness Berger 47

Peroxide Bleach + Peroxide Bleach whiteness Berger 53

Acid Cracking + Chlorite Bleach whiteness Berger 73

+ Peroxide Bleachmaterial: 100% linen rovecountry: Lithuania

material: 100% linen rovecountry: Lithuania

Bulk trialsCirculation apparatus

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Textile Effects

Aim removing of

Washing to remove Dirt and extrenous matter Degumming Oxidative Bleaching Reductive bleaching

Principle The washing is done

in discontinuous or continuous machinery as detergent or solvent scouring

Aim removing of

Washing to remove Dirt and extrenous matter Degumming Oxidative Bleaching Reductive bleaching

Principle The washing is done

in discontinuous or continuous machinery as detergent or solvent scouring

Pretreatment of Silk

Page 47: Pre Treatment

Textile Effects

22%

9%

21%

48%

grease suint sand, dirt, nat. impurities wool fibre

wool type: superfine merino

WoolWoolRaw wool - impurities (example)Raw wool - impurities (example)

Page 48: Pre Treatment

Textile Effects

Washing / scouring

Crabbing / potting

Milling

Carbonizing

Chlorinating

Bleaching(oxidative, reductive)

WoolWoolPretreatment processesPretreatment processes

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Textile Effects

Typical process route for viscoseTypical process route for viscoseg

rey s

tate

dyein

g,

pri

nti

ng

, fi

nis

hin

g Washing/Desizing

Washing/Desizing Caustifying

Caustifying Washing

Washing/Desizing Caustifying Bleaching

VISCO-COMBI-BATCH Washing

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Textile Effects

combines the conventional sequence of processing:

Desizing (oxidative)

Cleaning (removal of spinning oils and preparations)

Bleaching

Caustifying

VISCO – COMBI – BatchAn ace in Ciba preparation

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Textile Effects

A combination of different steps (desizing - caustifying -

bleaching)

which results in a considerable rationalization of water

consumption,

energy and time

No special separate machinery is required

Extremely clean fabric with a very good removal of all

disturbing

residuals such as size, oils, waxes, sulphuric components,

inorganic and metallic impurities, ….

Avoidance of folding and creasing as it is an open-width

batching process

An almost complete caustifying effect in terms of color yield

enhancement

can be obtained while safeguarding a soft and bulky handle

Benefits of the VISCO – COMBI – Batch

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Textile Effects

PB ENZ PB CPB VCB VCB with silicate/16h 16h

16h

Ciba® TINOZYM® AL g/l 10 - - -

Ciba® ULTRAVON® CN g/l 5 5 5 5Ciba® INVATEX® CRA g/l - 3 3 3Ciba® TINOCLARITE® BS g/l - 5 -

-Ciba® TINOCLARITE® CBB g/l - - 12

12silicate 38°Bé ml/l - 8 - -NaOH 100% g/l - 10 40 40H2O2 35% ml/l - 30 10 30

Color Strength in %Printing - green (reactive) 100 82 130 105 - orange (reactive) 100 88 124 115 - brown (reactive) 100 86 142 128Dyeing - red (direct) 100 92 113 110 - blue (reactive) 100 108 131

128

Color yield improvement on viscoseAfter different processes