28007961 introduction to dyeing and finishing technology on polyester fibre and its blends

8/4/2019 28007961 Introduction to Dyeing and Finishing Technology on Polyester Fibre and Its Blends

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Dyeing andDyeing andFinishingFinishingtechnology ontechnology on

Polyester fibrePolyester fibre andandits blendsits blends

Wirote SarakarnkosolWirote Sarakarnkosol


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OutlineOutline

Preparation of polyester fiber

Disperse dyes

Dyeing and auxiliary for polyester fiber Finishing on polyester

Polyester blends dyeing


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PolyesterPolyester

Most popular in synthetic fibres

Hydrophobic

High strength and good mechanicalproperty

Rapid growth in fibre blends

Can be modified to variation of finishing


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Variation in market share ofVariation in market share offibresfibres

FiberWorld share (%)

1980 1990 2000 (est) 2010 (est)

Cotton 47 47 40 31

Wool 5.4 4.2 2.6 2.0

Regenerated cellulose

(staple and filament)11.5 8.1 4.8 4.1

Polyester


Nylon(staple and filament)

9.9 9.6 7.3 6.6

Polypropylene


Acrylic 6.8 5.8 5.0 4.6

total 100 100 100 100


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Preparation of polyester fibresPreparation of polyester fibresfor dyeingfor dyeing

Scouring

Bleaching

Weight reduction

Heat setting


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Sizing agents for different substrates


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Scouring :Scouring :

PES contain larger quantities ofprocessing aid and oily dirt

General recipe for washing1 g/l non-ionic detergent

2 g/l soda ash

1 g/l sequestering agent

95oC on a tensionless open-width washing range

Not only remove the size and processingaid : Also developing bulk for texture yarn

Sometime calls RELAXATION


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Bleaching :Bleaching :

Rarely necessary for 100% PES

NaClO2 is only effective

Higher whiteness can be achieved withnonionic FWA

Condition for PES/CEL and PES/WO will

depend on the blends fiber


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AOX values of NaClOAOX values of NaClO22 ononvarious synthetic fibervarious synthetic fiber

Sizes and lubricants are often prime sources of higherAOX values rather than the substrate itself

Effect of surfactant addition on AOX values after chlorite bleaching ofsynthetic fibres


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Alkaline pretreatment for weightAlkaline pretreatment for weightreductionreduction

NaOH has been used to achieved aweight reduction of 10-15%

Result in improve handleand hydrophilicity Degree of weight reduction depend on

concentration of NaOH, Temperature andtreatment time.

Cationic accelerating agent can use as thecatalyst for weight reduction


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Heat setting :Heat setting :

Serve to stabilise polyester fabric and

retain the shape of fabric

Condition are governed by the processinghistory as guide condition

Woven and knitted good of texture filament :

170-190oC

Polyester filament : 185-220oC PES/CEL blends : 190-210oC


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Heat setting :Heat setting :

Should avoid problems with shade

variations during dyeing

Pre-setting has a negative on dye yields. Post-setting generally adversely fastness

and colour change particular for ring

dyeing or incompatible dyestuffs.

Sublimation fastness of selected dyes

should be concerned.


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Disperse dyes : ChemistryDisperse dyes : Chemistry

Hydrophobic and nonionised

Can be classified as Azo dyes

Anthraquinone dyes

Styryl (Methine) dyes

Nitrodiphenylamine dyes

Heterocyclic ring structure dyes

Benzodifuranone dyes Thiophene dyes

Etc. but not phthalocyanine


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Chemical structure present inChemical structure present incolorant of variation of huescolorant of variation of hues

Hue Typically chemical structure

Brillant Yellow Methine ; Coumarin ; Pyridone

Yellow Nitrodiphenylamine ; Heterocyclic ; Azo with pyridone coupler

Orange Azo

Red Azo; Anthraquinone ; Benzodifuranone

Pink Anthraquinone ; Benzodifuranone

Violet Azo; Anthraquinone

Blue Azo; Anthraquinone ; Thiophene

Black Mix of azo


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Classification of Disperse dyesClassification of Disperse dyeswith dyeing propertywith dyeing property

Class A : Low MW , High migration

Low sublimation fastness for acetate fibre

Class B : Slightly Higher MW, Lower migration

Suitable for carrier dyeing on PES

Class C : Higher MW, Lower migration than

Class B

Suitable for HT dyeing on PES Class D : Highest MW, Lowest migration

Suitable for Pad-Thermosol on PES


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Disperse dye :Disperse dye :Commercial nameCommercial name

Dianix (Dystar)

Terasil (Huntmann)

Foron (Clariant) Sumikaron (Sumitomo)


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Alkaline clearable disperse dyesAlkaline clearable disperse dyes

Must control dyeing pH below 5 (or some pH 4)

Avoidance of a reduction clear with dithionite as

conventional disperse dyes.

Minimal cross-staining of the cellulosic fibre

Minimal processing time because the alkaline

fixation for reactive dyes clears the disperse dye

stain. Good washing fastness performance after heat

setting during finishing.


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Mechanism of alkali clearingMechanism of alkali clearing

Undergoes hydrolyse

under relatively mild

alkaline conditions to give

a water-soluble structure

Lability of the thienyl ring

system are easy to alkali

clearing than normal

Undergoes hydrolyse

under relatively mild

alkaline conditions to give

a pigment and cant stain

on fabric


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Essencial auxiliary for disperseEssencial auxiliary for dispersedyeingdyeing

Dispersing agents

pH control and sequestering agents

Electrolytes Levelling agents

Carriers

Antireduction


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Dispersing agentDispersing agent Disperse dyes being an

overall tendency of fineparticles to formation oflarger particles

Beam and packagedemands on initialdispersion andsubsequent stabilityunder adverse conditions

Jig dyeing with a high

concentration of dye in avery short liquor (as fornavy blues and blacks)can also be the source ofdispersion stabilityproblems.


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Effect of temperature changes on theparticle size distribution in a dyebathcontaining 0.6% CI Disperse Orange 13


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Typical conventional dispersing agentTypical conventional dispersing agentcondensation product of naphthalene-2-

sulphonic acid and formaldehyde

lignosulphonate

condensation products ofp-cresol and 2-naphthol-6-

sulphonic acid with formaldehyde and sodium bisulphitecondensation products of phenols withformaldehyde and sodium sulphite


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Dependence of dispersion thermalstability on dispersing agent structure


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Effect on reduction of sensitiveEffect on reduction of sensitivedyesdyes

LignosulphonatePresence in lignin of catechol residues

and other easily oxidised functional groups

Naphthalene-sulphonate

condensation types

Higher promote

reduction

of sensitive dyes


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pH control:

Many disperse dyes give good results over an

extensive pH range (pH 29)

Some will only give satisfactory results over a

narrower acidic range (pH 26)

Few require careful control (pH 4 - 5.5)

Practically all dyes

provide good results

at pH 5


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pH control:pH control: pH value of some common acid in distilled water.pH value of some common acid in distilled water.

Normality2 N 1 N 0.1 N x N 0.01 N 0.001 N

Material

Hydrochloric acid g/l - 36.5 3.65 1 g/l 0.37 0.037

HCl pH - 0.11 1.08 1.61 2.00 3.00

Sulphuric acid g/l - 49.0 4.9 1 g/l 0.49 0.049

H2SO4 pH - 0.24 1.17 1.79 2.05 3.00

Formic acid g/l 92.0 46.0 4.60 1 g/l 0.46 0.046

HCOOH pH 1.61 1.79 2.32 2.76 2.85 3.42

Lactic acid g/l 180.0 90.0 9.00 1 g/l 0.90 0.090

C3H6O3 pH 1.78 1.97 2.43 2.94 2.95 3.50

Acetic acid g/l 120.0 60.0 6.00 1 g/l 0.60 0.060

CH3COOH pH 2.18 2.40 2.87 3.27 3.37 3.89


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Alkaline dyeing of polyesterAlkaline dyeing of polyester

Mitsubishi kasei (Dystar japan) announce

in 1993

Over 30% oligomer reduction

Cleaner machinery

Time saving (270 min to 190 min)

Reduced BOD/COD in effluent

Water and energy saving (2/3 cost with

normal condition)


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EEssential primary requirementfor alkaline dyeing

Selecting disperse dyes that are stable to

pH 9.5 at least

Use the buffer which can Stabilise the dyes

Provide adequate buffering

Chelate metal ions

Assist dissolution of oligomers


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Alkaline buffer for alkalineAlkaline buffer for alkalinedyeingdyeing

Extensive range of amino acid derivatives applied in

combination with an alkali

N,N-bis(hydroxyethyl)glycine in combination with sodium

hydroxide

N,N-dimethylglycine, N-methylglycine and N-

methylalanine are also listed as preferred compounds

N,N-bis(hydroxyethyl)glycine


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Sequestering agentSequestering agent and importantand importantfactors for selectionfactors for selection

Sequestering power. Ability for removal or the neutralizing of harmful metal ions

(water hardening substances, heavy metal ions) from thewater.

Complex stability constant. Equilibrium constant of COMPLEX : FREE LIGAND.

Dispersibility. Ability to distributed the solid particle in liquid.

Buffer capacity. Maintain the pH of solution as narrow or constant.


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Typical of sequestering agentTypical of sequestering agentfor disperse dyeingfor disperse dyeing

Aminopolycarboxylate Advantages:

High selectivity for heavy metal ions

Good stability at increased temperatures Good alkali resistance.

Organic phosphonate Advantages:

High calcium, magnesium and iron binding capacity

Very selective effect on polyvalent heavy metal ions

Effective in the lower stoichiometric region.


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ElectrolyteElectrolyte

Unnecessary for the application of

disperse dyes alone.

High concentration of salt often used withreactive dyes can have an adverse effect

on dispersion stability.

Electrolyte-stable formulations of

disperse dyes or auxiliaries should be

selected.


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Levelling agentsLevelling agents

Dispersing agents Promote level dyeing by control of exhaustion during the

heating phase of dyeing

Higher concentrations have a greater retarding effect.

Few promote dye migration.

Levelling agents Tend to solubilise the dye much more effectively

Contribute to level dyeing both by a retarding effect and

through the promotion of migration.

Generally more powerful levelling effects.


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Levelling agentLevelling agent

Non-ionic levelling agent tend to be separated at hightemperature but can increase dyes solubilisation (Lowcloud point)

Anionic levelling agent can increase the cloud point ofnonionic agent

Should synergistic mixing together

7-10% of B in A can increase cloud point of A alone(105oC) to 150oC

Fully effective at pH >7 (Carefully selection of dyes)

(A) fatty acid ethoxylate (B) sodiumdodecylbenzenesulphonate


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Levelling agent for disperse dyesLevelling agent for disperse dyes

Modified nonionic (or Modified anionic,

Weakly anionic)

Phosphate ester ethoxylation

High temperature stability

Protect hardness and trace metal ion

Stabilise under high concentration of electrolyte

Fully effective at pH 4-5 (pH of disperse dyeing)


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Levelling agent for disperse dyesLevelling agent for disperse dyes

Oligo-soaps or Ethoxylated multi-ester

compounds. More stable dye dispersion at high temperature

Solubilisation take place at a lower temperature

Dyeing rate at lower temp. is much slower

Solubilisation of oligomer and acrylic size

Low foaming


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CarriersCarriers

Although polyester fibres are normally

dyed at high temperatures, their blends

with wool are still dyed at or near the boil.

Qualities of texturised polyester that suffer

loss of crimp at 130 C.


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Harmful effects from carrierdyeing : 3 ways

Residual carrier in the dyebath contributes to

effluent pollution and may be environmentally

harmful

Carrier that is volatilised during dyeing orsubsequent heat setting becomes an

atmospheric contaminant

Residual carrier in the fibre can be a health

hazard, as well as causing an unpleasant odour

on heating or during storage.


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Typical and properties of someTypical and properties of somecarrier based.carrier based.

o-Phenylphenol, tend to lower the light fastness of manydyes if carrier residues remain in the dyed fibre.

Chlorobenzenes, have no effect on this property, butstrong odour and are both toxic and difficult to

biodegrade. Biphenyl is relatively non-toxic to river life but is not

readily biodegradable.

Methylnaphthalene, also of low toxicity, is moderatelybiodegradable.

Butyl benzoate are relatively efficient in promotingmigration on PES/WO blends

N-alkylphthalimide have no odour and good efficiency


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Dyeing of polyesterDyeing of polyester

Carrier dyeing at near or at boiling

temperature

HT dyeing at 120 140o

C Pad-Thermosol dyeing


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Mechanism of disperse dyeingMechanism of disperse dyeingduring processduring process

Temperature

TimeDiffusion

phase

Migration

phase

Relaxation

phase

Boiling with carrier/

130oC without carrier

CDT

CDT ; Critical dyeing temperature

Range of 80 120o

C


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Troubleshooting during dyeingTroubleshooting during dyeing

Disperse dye reduction in the dyebath

Disperse dye hydrolysis in the

dyebath


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Disperse dye reduction in thedyebath:

The amines resulting from A and B do not dye polyester, or only dye it a

weak yellowish shade.


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Unfavourable conditions ofreduction of disperse azo dyes

Risk for dyes

pH > 6

anaerobicdyeing

conditions

Blend fibres

containing

reducing

groups

Reducing

metal ions

(Cu+

, Fe++

)

Phenolic

dispersing

agents

slower

dyeing

High

density

fiber

auxiliaries

to solubilise

the dye too

much


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Disperse dye hydrolysis in thedyebath.

A: The hydrolysed dye gives bluer red dyeings than the esterified on polyester.

B: The hydrolyzed dye dyes polyester only a little.


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How to solve?How to solve?

Reduction during dyeing Remove trace metal ion (Sequestering agent)

Replace the lignosulphonate/napthalene

sulphonate with others (Levelling agent) Accelerate to the appropriate dyeing rate (Carrier

or Accelerating agent)

Hydrolysation during dyeing Control to acidic pH range (pH controller)

Accelerate to the appropriate dyeing rate (Carrier

or Accelerating agent)


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Reduction clearingReduction clearing Reducing agent with appropriate condition

Alkaline condition Hydros stabilise (conventional)

Thiourea dioxide

Acidic condition

Reducing agent with acidic pH (formulated reducing agent) e.g.sulphinic acid derivative with suitable catalyst

No pH changes needed,

Low COD, high biodegradability, low toxicity,

Savings of time and water consumption

Washing fastness as the hydros/caustic soda for disperse azo dyes.

But not for anthraquinone or other chemical type.

Temperature should not > 70oC (higher than wet-Tg ofpolyester)

Surfactant can increase the efficiency of reductionclearing.


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Reduction clearing of Disperse azoReduction clearing of Disperse azodyesdyes

CI Disperse Orange 5

Example

l

l

O

H

H H OH

HH

l

l

O H

H

H H OH

+


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Reducing agent :Reducing agent :Fastness of black polyester dyeings after various reduction clearingFastness of black polyester dyeings after various reduction clearingtreatmentstreatments


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Moisture management of polyesterMoisture management of polyester(PES)(PES)

Hydrophobic interaction with oil.

Electric static force provide the soil and

uncomfortable wearing. Chemical should provide the hydrophilicity

on the fiber surface.


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Schematic of Short chainSchematic of Short chainhydrophilic polyester action on PEShydrophilic polyester action on PES


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Typical short chain hydrophilicTypical short chain hydrophilicpolyesterpolyester

> 51,000 Patents

Very complex area


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Detergency with & without a soilDetergency with & without a soilrelease polymer (SRP)release polymer (SRP)


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ThermomigrationThermomigration

Degree of thermomigration depend on structureof a dye, MW, diffusion coefficient or fastness tosublimation.

Temperature has a greater effect than time in

promoting thermomigration. Silicone softener and hydrophilic polyester can

increase thermomigration.

The application by padding of an organotin

catalyst along with any other finishing agentsgives rise to a reducing effect during subsequentdry heat treatment.


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Cause of wash fastnessCause of wash fastnessproblems on polyesterproblems on polyester

Polyester fiber Dye on fiber surface Heat set/

Chemical finish

dyeing Reduction

clear

Pressing/

storage

Consumer

washing

Staining on white adjacent


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Colour change after heat settingColour change after heat settingof incompatible dyesof incompatible dyes

Heat setting

Dyeing with blends of

Low diffusion blue/

High diffusion yellow

Blue migrate to inside

Yellow migrate to surface

Greener

Colour change


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Conclusion :Conclusion :

Polyester can be dyed with disperse dyes

which can adsorb as the solid solution.

The optimum dyeing conditions of

disperse dyes are depend on the disperse

dyes type and fabric type.

The quality of water and careful auxiliaries

selection is the important parameter forreproducibility.


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28007961 introduction to dyeing and finishing technology on polyester fibre and its blends

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