Presentation_WPT CLT IV

8/2/2019 Presentation_WPT CLT IV

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DYES FOR POLYESTER FIBRE


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Members Md. Arifur Rahman

Roll-08

Paritosh Chandra Dash

Roll-20 Md. Abdur Rashid

Roll-35

Hazrat Ali

Roll-41 Md. Shihabul Islam

Roll-44


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Man made fibre

85% or more ester of substituted aromatic carboxylic acid.

Produce by reacting ethylene glycol with either terephtalicacid or its methyl ester in the presence of an antimonycatalyst.

Temperature 300C

Five to eight hours.


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Wallace Carothers in 1920 first introduce filamentproduction process.

Polyester was first produce in 1940 byCalico PrintersAssociation in Great Britain.

Polyester was commercialized in the 1950.


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Tensile Strength:

High tenacity filament: 7,350-8,750 kg/cm2 (105,000-

125000 lb/in2

) Medium tenacity filament: 4,900-5,950 kg/cm2

(70,000-85,000 lb/in2)

High tenacity staple: 5,250-7,350 kg/cm2 (75,000-

105,000 lb/in2) Medium tenacity staple: 4,900-5,950 kg/cm2 (70,000-

85,000 lb/in2)


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Elongation:

High tenacity filament: 8-11 per cent (depending ontype)

Medium tenacity filament: 15-30 per cent High tenacity staple: 20-30 per cent

Medium tenacity staple: 30-50 per cent

The extension at break is virtually unaffected by

moisture.


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Elastic Recovery:

Terylene fibres have a good recovery from stretch, and

from compression, bending and share.


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Average Toughness:

High tenacity filament: 0.325 g.-cm./denier-cm

Medium tenacity filament: 0.50 g.-cm./denier-cm

Medium tenacity staple: 0.61 g.-cm./denier-cm


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Abrasion resistance:

For identically constructed materials, the abrasion

resistance of standard Terylne is of a high ordercompared with that of most textile fibres, both naturaland man-made, being exceeded only by nylon amongthe commoner fibres.


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Specific Gravity:

1.38

Thermal Properties: Softening point: 260C, approx

Sticking temp: 230-240C

Specific heat: 0.27cal./g.deg.C.at 20C


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Effect of sunlight:

Terylene has a high resistance to degradation bylight. After prolonged exposure, it suffers a gradualloss of s Heat:

The fibre becomes tacky at 235 C and melts at 250 C

trength, but does not discolour.


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Bleaches:

Not affect by oxidizing or reducing bleaches.

Stains:

Resistance to water borne. Flammability:

Burns slowly will shrink away from flame, yet willexhibit melt drip.

Dye ability:

Disperse and azoic dyes and some pigments are used.


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Acids: Polyester is very resistant, even to mineral acid and thus has this

advantage over the polyamides concentrated sulfuric aciddisintegrate the fibre.

Alkalis: Resistance to alkali, although an ester, the relatively

impenetrable structure restricts alkaline attack to the surface.Strong hot alkalis results in a slow thinning of the diameter bysaponification.

Organic solvent: Adequate all round resistance including dry cleaning solvents.


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Azoic Dyestuffs-Produce bright reds &marrons,a black & a navy blue.

-Good fastness to washing but poor rubbing fastnessafter steam/heat setting in case of azoic red & marrons.

Vat Dyestuffs-Limited range of shades

-Build up to only medium depths

Disperse Dyestuffs

-A wide range of shades is available-Color fastness to wash, light,rubbing etc .is good

- mainly use for polyester fibre dyeing


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Non ionic dyes Insoluble in water

Suitable for dyeing hydrophobic fibres

Mainly used for dyeing synthetic fibres speciallyacetate & polyester fibres

Carrier or dispersing agents are used

Fair to good light fastness

Moderate to good wash fastnessApplied in acidic medium

Smallest molecular size


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According to Chemical structure:

a). Nitro dyes

b). Amino ketone dyes

c). Anthraquinonoid dyes

d). Mono azo dyese). Di-azo dyes

According to Fastness properties:

a). Group A (Excellent dyeing & good fastness properties)

b). Group B (Excellent in HT & Carrier dyeing with moderatefastness)

c). Group C ( Moderate in HT & Carrier dyeing with higherfastness properties than Group B)

d). Group D ( Excellent fastness to heat)


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According to energy level:

a). Low energy dyes ( Used to dye with carrier,poor resistance to sublimation, 77C tem required)

b). Medium energy dyes (Required temp. 104-110C,better sublimation fastness than low energydyes)

c). High energy dyes ( suitable for continuous

dyeing, temp. above 129C , all round fastnessproperties)


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Mono azo dyes = 50%Anthraquinonoid dyes = 25%

Di azo dyes = 10%

Methyne dyes = 3%

Styryl dyes = 3%

Acrylene benzimidazol = 3%

Quinonaphthalon dyes = 3%

Amino napthyl amide = 1%Naphthaquinone amine = 1%

Nitro disperse dyes = 1%


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Normal dyeing method:dyeing temp.80-100c

Carrier dyeing method :dyeing temp.80-100c

High temp.dyeing method: dyeing temp.105-140c

Thermasol dyeing method: continuous method ofdyeing,dyeing temp.180-220c

Pad roll method:semi continuous dyeing method

Pad steam method: continuous dyeing method


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1. Available dyeing machines

2. Required color effect

3. Required color fastness

4. Type of material to be dyed5. Cost of dye,chemicals & auxiliaries

6. Overall economy of the syestem

7. Dyeing temperature


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Temperature:

In case of high temperature dyeing method ,temperature above 100 C is required for swelling offibers

In case of carrier dyeing method swelling occurs at 85-90C

In case of thermosol dyeing method, if temperature is

kept more, fabric is kept for less time in thermosolunit. If it is kept more time dye sublimation and loss offabric strength may occur


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In high temperature solubility of disperse dye increase

PH :

PH should be 4.5-5.5

For maintaining PH

generally acetic acid is used At this pH dye exhaustion is satisfactory

Correct pH should be maintained otherwise fastnesswill be inferior and colour will be unstable.


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To modify crystalline structure.

To improve dimensional stability.

To resist creasing during dyeing and washing. To increase safe ironing temperature.

To avoid shade variation.

Affect water inhibition.


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By reduction cleaning surface dye molecules or unfixeddye molecules are strippd after dyeing and this resultin level dyeing .

It also improves wash fastness

A typical recipe for reduction cleaning-

Detergent = 1g/l

Hydrose = 2g/l

Caustic soda = 2-3 g/l


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The dyeing is considered to take place in the followingsimultaneous steps:

Diffusion of dye in solid phase into water by breakingup into individual molecules. This diffusion depends

on dispersibility and solubility of dyestuff and is aidedby the presence of dispersing agents and increasingtemperature.

Adsorption of the dissolved dye from the solution onto

the fibre surface. This dyestuff adsorption by fibresurface is influenced by the solubility of the dye in thedye bath and that in the fibre.


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Diffusion of the adsorbed dye from the fibre surface into theinterior of the fibre substance towards the centre. In normalcondition, the adsorption rate is always higher than the diffusionrate. And this is the governing step of dyeing.

When equilibrium dyeing is reached, the following equilibria arealso established:

Dye dispersed in the bath Dye dissolved in thebath

Dye dissolved in the bath Dye adsorbed on thefibre Dye adsorbed on the fibre Dye diffused in the

fibre


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There are mainly three method

1.Carrier Dyeing Method2.High temp. & High pressure Method3.Thermasol Method


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Dye - For light shade1.5%

Carrier (phenol) : 2-5%

Acetic acid : 1gm/lit Dispersing agent:1- 2gm/lit

Sequestering agent: 1-2gm/lit

pH :4-5.5

M:L : 1:10 Time : 60-120 min

Temperature : 90-100C


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It creates dye film on fibre surface.

Carrier takes dye inside the fibre from dye carrierassociation.

It increases the solubility of dye in the dye bath. Carriers penetrate inside the fibre polymer chain and

thereby reduce inter-chain attraction. Thus polymerchains become movable and so dye molecules may

enter the polymer system of fibre. It increases fibre swelling.


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The absorbed carrier increases the rate of dye uptakeby creating liquid co-fibre.

It increases the absorbency power of fibre.

It lubricates the thermally agitated fibre molecules. 2-10 gm/lit carrier is used depending on material and

liquor ratio and depth of shade


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Dye : 3%

Dispersing agent: 1-2gm/lit

Sequestering agent:1-2 gm/lit Acetic acid : 1gm/lit

Time : 60 min

Temperature : 130C

pH : 4-5.5

M:L : 1:10


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Thermasol method is continuous methods of dyeingwith disperse dye. Here dyeing is performed at hightemperature like 180-220C in a close vessel. Here timeof dyeing should be maintained very carefully to get

required shade and to retain required fabric strength. It requires only a few seconds to 1 min and

temperature about 200-230C.


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The sequence of operation is:

Padding drying Thermofixing Aftertreatment


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At first the fabric is padded with dye solution usingabove recipe in a three bowl padding mangle.

Then the fabric is dried at 100C temperature in dryer.For dyeing, infra red drying method is an ideal methodby which water is evaporated from fabric in vaporform. This eliminates the migration of dye particles.


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Then the fabric is passed through thermasol unitwhere thermo fixing is done at about 205C temp for60-90 seconds depending on type of fibre, dye anddepth of shade. In thermasol process about 75-90%

dye is fixed on fabric. After thermo fixing the unfixed dyes are washed off

along with thickener and other chemicals by warmwater.

Then soap wash or reduction cleaning is done ifrequired.


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Presentation_WPT CLT IV