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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