dyeing presentation

8/7/2019 Dyeing Presentation

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ACETATE FIBERS

PRESENTED BY:

MUHAMMAD AFZAAL SADIQ

06-NTU-077

ADNAN LATIF

06-NTU-103


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ACETATE FIBERS

Word Acetate derived from

Acet Acetic acid

Ate Chemical salt

Hence

Acetate Salt of acetic acid


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CELLULOSE ACETATE

Compound of cellulose and acetic acid

Cellulose Acetate 54 55 % combined acetic acid

Cellulose Triacetate 60 % combined acetic acid


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ACETATE POLYMER These are polymers of cellulose whose OH have

been acetylated

Cellulose triacetate produced first so known asprimary acetate

Primary acetate is then hydrolyzed to produce

cellulose acetate known as secondary acetate


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ACETATE POLYMER

Po ACETATE

40% crystalline

60% amorphous

So ACETATE

60% crystalline

40% amorphous


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HISTORY

First developed in ENGLAND during world war I by

Henri and Camille Dreyfus

Commercial production was begun in US in 1924

under the trade mark of CELANESE


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MANUFACTURING

ACETYLATION OF CELLULOSE

Cotton linters or wood chips are converted into sheets of

pure cellulose

Cellulose is steeped in glacial acetic acid under acontrolled temperatures for a period of time

Then it is mixed with acetic anhydride. A small amount of

sulfuric acid is added as a catalyst

This dope is mixed with excess water, causing the whiteflakes of cellulose acetate to be precipitate


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ACETYLATION OF CELLULOSE

These flakes are then dissolved in acetone and

filtered several times to remove impurities

This result pure white spinning solution

If delustered yarn is to produce small amount oftitanium dioxide is added

Spinning solution is extruded in column of warm air

through spinneret and solvent recovered

Filaments are stretched and wound onto beams, cones,or bobbins ready for use

This technique of spinning is called DRY SPINNING


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PHYSICAL FORMS OF ACETATE

Filament yarn

Monofilament yarn

Multifilament yarn

Textured yarn

Spun yarn(size of filaments are reduced in 1 6

inches)


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TRADEMARKS OF ACETATE FIBERS

TRADE MARK MANUFACTURER TYPE

Avtex acetate Avtex fibers Inc. Multifilament

Celanese acetate Celanese fibers marketing Co. Multifilament , Staple, Tow

Chromspun Eastmen chemical products Inc Multifilament

Estron Eastmen chemical products Inc Multifilament

Estron SIR Eastmen chemical products Inc Multifilament


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GENERAL CAHRACTERISTICS Shrink resistant

Wrinkle resistant

Easily washable

Generally washable at high temperatures Maintains creases and pleats well

Particularly effective in clothing where crease orpleat retention is important, such as skirts and

dresses.


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PHYSICAL PROPERTIES

Handle Soft

Smooth

Crisp and resilient

Comfort Breatheable

Dries quickly

No static cling

Drape

Good


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PHYSICAL PROPERTIESLuster

Light reflection creates a exellent appearance

Performance

Colorfast to perspiration staining

Colorfast to dry cleaning Air and vapor permeable

Tenacity

Weak fiber with breaking tenacity of 1.2 to 1.4g/denier

Rapidly loses strength when wet


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PHYSICAL PROPERTIES

Abrasion

Poor abrasion resistance

Heat setting

Triacetate softens on heating Sticking and glazing can occur during ironing at

temperatures above 180oC

Show more resistant to glazing after heat setting

at high melting point at 300oC


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CHEMICAL PROPERTIES

Effect of acid

Resistant to weak acid

Dissolved in strong acid including glacial acetic acideven at low temperatures

Effect of alkali

Cellulose acetate is saponified by the action of alkali

Triacetate is more resistant to alkali. Only mild surfacesaponification occurs with sosium hydroxide at elevated

temperatures. Delustring occurs at temperatures above 85oC


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CHEMICAL PROPERTIES

Effect of solvent

These fibers are swollen by certain chemicals.

This technique is used in carrier dyeing Tetrachloroethylene solvent is used for dry

cleaning purposes.


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PRE-TREATMENT PROCESSES

Scouring/ Desizing

S- finish

Bleaching

Heat setting


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PRE-TREATMENT

SCOURING

1 2 ml/L detergents at 60oC 80oC are sufficient

pH must not exceed 9.5


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PRE-TREATMENT

S- FINISH Partially saponify the fiber to reduce acetyl value

from 62% to 59%

Carried out with 3 6 g/L sod.hydroxide at 80oC

85oC for 60 90 min depending on machinery typeand liquor ratio

Advantages

Improved soil resistance

Improved resistance to glazing Increased resistance to gas fume fading

Increased fastness to wet and dry rubbing


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PRE-TREATMENT

BLEACHING

Historically sodium chlorite applied at 75 85 oC at pH 4with oxalic or formic acid. This type of bleaching is

followed by anti chlor treatment. Hydrogen peroxide gives low degree of whitness specially

in blends with natural fibers.

pH should not exceed 10

bleach activator may be added to give sufficientwhitness TAED(tetra acetylethylenediamine) SNOBS(sodium nonanoyloxybenzenesulphonate)


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PRE-TREATMENT

HEAT SETTING

Dry heat setting is most common method using hot

air as heat transfer medium at stenters

Air flow must be balanced Wide width must be supported to avoid snagging

and distortion

Occurs rapidly in range 210oC 220oC

Slowly in range of180oC 210oC


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DYEING

PARAMTERS TO CONTROLL DYEING

Addition of chemicals such as alkali ,acid or

electrolyte

Time

Temperature

Most important parameter to controldyeing is TEMPERATURE


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DYE BATH ADDITIVESDispersing agent

To assist in dye size reduction.

To maintain uniform dispersion during dyeing.

Although dispersing agent is grinded with disperse

dye yet additional dispersing agent is added as a

wise precaution.


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DYE BATH ADDITIVES

Leveling agent

Increased migration.

Increased leveling.

Increased fiber penetration.

Less tendency of listing and ending in jigger

machine.


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DYE BATH ADDITIVES

Carrier

Preferably used for triacetate fibers.

Use for dark to medium shades with disperse dye Improved penetration of dye

Improved wet fastness

Diethyl phthalate mostly recommended


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DYE FIBER INTERACTION

The dye-fibre affinity is the result of different types of

interactions:

Hydrogen bonds

Dipole-dipole interactions

Van der Waals forces


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DYE FIBER INTERACTION

Hydrogen bonds

Disperse dyes have hydrogen atoms in their molecule, which

are capable of forming hydrogen bonds with oxygen and

nitrogen atoms on the fiber.

Dipole-dipole interactions

Dipole-dipole interactions result from the asymmetrical

structure of the dye molecules, which makes possibleelectrostatic interactions between dipoles on the dye

molecules and polarized bonds on the fiber.


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DYE FIBER IN

TERACTION

Van der Waals forces

Van der Waals forces take effect when the molecules

of the fibre and colourant are aligned and close toeach other. These forces are very important in

polyester fibres.


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ACETATE PRODUCTS TO BE DYE

Loose fiber/stock

Yarn Fabric

Dyeing on jigger

Dyeing winch

Dyeing on jet


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LOOSE FIBER/STOCK DYEING

Liquor is circulated for a short time under ambienttemperature, then drained

Dye bath is set at 40oC with dispersing agent and pH

5 6 with acetic acid or buffer

Temperature is raised to

85oC for acetate

98oC for triacetate

110

o

C in case of pressurized machine Liquor flow is from in to out throughout the dyeing

process


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LOOSE FIBER/STOCK DYEING

Temperature is maintained atleast for 1 hour

Dyebath then drained

Rinse cold

Rinse warm at 40oC Heavy shade are soaped or mild reduction clear

2 g/L sod.hydrosulphite

2 g/L sod carbonate

Detergent (non ionic) Temperature 40oC for acetate and 55oC for triacetate

Neutralizing and washing


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YARN DYEING

Wound on a perforated cone Winding density is kept low

Same conditions are given as in case of loose

fiber/stock


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FABRIC DYEING ON JIGGER

Half of dispersed and sieved dye is added

pH is adjusted to 5 6

Temperature is raised

At dyeing temperature rest of the half dye is added

Appropriate time is given depending on shade depth

Dyebath is drained

Rinsing through warm water


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PROBLEMS IN JIG DYEING Tension under hot, wet conditions lead to fabric

extension

Open jiggers leads to cooling of fabric rolls Reduced dyeing rate

Specially at selvedges

Ending is more common

REMEDIES

Use saturated steam

Used high pressure jigger or close lid jigger


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FABRIC DYEING ON WINCH

Dyebath is set at 40oC and pH 5 6 with suitable

dispersing agent

Fabric lubricant and anti crease agents must be added

Circulation time for 10 min are given Dispersed and sieved dye is added

Temperature is raised to 85oC for acetate

to boil for triacetate

Temperature must be raised at rate of 1oC /min


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FABRIC DYEING ON WINCH Appropriate dyeing time is given depending on

shade depth (30 60 min)

Dyeing bath then cooled at rate of 2oC / min at

55oC and then drained

Rinsing followed by reduction clearing

SPAECAIL CARES IN WINCH DYEING

Fabric must not prone to rope creasing or

formation of crack mark Care must be taken to avoid crease formation

Fabrics must be pre relaxed to dyeing


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FABRIC DYEING ON JET

Same procedure as followed in winch dyeing but

soft gentle action must be given in jet

SPECAILITY

Temperature can be raised to130oC

Dyeing can be carried without carrier

Wide range of dyestuff can be used


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FASTNESS PROPERTIES

Wet fastness Poor to moderate

Light fastness

Moderate to good


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LIGHT FASTNESS Catalytic fading

Individual dye show good light fastness but

combination shade show poor light fastness

Anomalous fading

In combination shade fading of one dye is

catalyzed by other dye

Tetra substituted anthraquinone derivatives mostfrequently act as activator


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ABNORMAL FADING

Gas fume fading

Also known as abnormal fading

Fading on long term storage Anthraquinone based dye show this type of fading

To prevent this gas fading inhibitor is used, mostly

based on diphenylacetamide.


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THANKS

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