lecture 4 dyeing basics
TRANSCRIPT
DYEING: DEFINITIONS
DYEING• UNIFORM COLOURATION OF TEXTILE MATERIAL IN
FIBRE, YARN OR FABRIC FORM.• THE COLOUR PRODUCED SHOULD WITHSTAND
EXTERNAL AGENCIES SUCH AS WASHING, LIGHT, RUBBING etc TO WHICH TEXTILE MATERIAL IS SUBJECTED DURING USE.
• THE COLOURATION SHOULD NOT RESTRICT ONLY TO THE FIBRE SURFACE BUT SHOULD PENETRATE THE FIBRE CROSS SECTION.
• THE SURFACE COLOURATION IS KNOWN AS RING DYEING.
DYES AND PIGMENTS
DYES• COLOUR COMPOUND• SOLUBLE IN WATER OR CAN BE MADE SOLUBLE IN
WATER• POSSESSES AFFINITY TO FIBRE TO BE DYED• PENETRATION OF DYE IN FIBRE CROSS-SECTION
UNDER DYEING CONDITIONS• INTERACT WITH FIBRE WITH SUITBLE DYE-FIBRE
INTERACTIVE FORCES DEPENDING ON THE NATURE OF FIBRE AND NATURE OF DYE
• NATURE OF DYE-FIBRE INTERACTION DETERMINES THE FASTNESS PROPERTY OF DYE TO EXTERNAL AGENCIES. THERE SOME EXCEPTIONS TO THIS RULE.
DYES AND PIGMENTS
TINTING COLOURS• DYES HAVING NO AFFINITY TO FIBRE. • EASILY REMOVED DURING WASHING
PIGMENTS• COLOURING COMPOUND• INSOLUBLE IN WATER• NO AFFINITY TO FIBRE• NO INTERACTION WITH FIBRE
AFFINITY OR SUBSTANTIVITY
• ATTRACTION BETWEEN DYE AND FIBRE UNDER GIVEN DYEING CONDITIONS.
• ABILITY OF DYE TO MOVE FROM SOLUTION PHASE TO FIBRE PHASE DURING THE DYEING OPERATION
• THIS MEANS REDUCTION IN DYE CONCENTRATION
IN SOLUTION PHASE AND CORRESPONDING
INCREASE OF DYE CONCENTRATION IN FIBRE
PHASE WITH DYEING TIME.
• DYES HAVE AFFINITY TO FIBRE
• PIGMENT AND TINTING COLOURS HAVE NO AFFINITY
TOWARDS FIBRE.
CLASSIFICATION OF DYES
WATER SOLUBLE SUITABILITY TO FIBRE• DIRECT COTTON, WOOL, SILK, NYLON• ACID WOOL, SILK, NYLON• BASIC OR CATIONIC MAINLY ACRYLIC, LIMITED WOOL,
SILK• REACTIVE MAINLY COTTON, LIMITED WOOL,
SILK• SOLUBILIZED VAT COTTON
WATER INSOLUBLE
• VAT COTTON• SULPHUR COTTON• DISPERSE MAINLY POLYESTER, LIMITED
NYLON, ACRYLIC IN-SITU COLOUR FORMATION
• AZOIC COTTON• OXIDATION COLOURS COTTON
PIGMENT COLOURS ALL FIBRES DEPENDING ON BINDER
THEORETICAL CONCEPT
DYEING PROCESS• FIBRE DYE BATH: DYE, WATER, DYEING
AUXILIARY• INTRODUCTION OF FIBRE IN DYE BATH• DYEING UNDER SUITABLE CONDITIONS FOR
SUITABLE LENGTH OF TIME• ZERO TIME ALL DYE IN DYE BATH• WITH PASSAGE OF TIME INCREASE IN DYE
CONCENTRATION ON FIBRE• CORRESPONDING DECREASE IN DYE
CONCENTRTION IN DYE BATH• THIS PHENOMENON IS KNOWN AS DYE EXHAUSTION
AND OCCURS DUE TO AFFINITY OF DYE FOR FIBRE
DYEING MECHANISM• DIVISION OF DYE SYSTEM IN THREE PHASES• DYE IN SOLUTION • FIBRE SURFACE• INTERIOR OF FIBRE• DURING DYEING THREE TYPES OF EQUILIBRIA EXIST• DYE IN SOLUTION DYE ON FIBRE SURFACE DYE IN THE
INTERIOR OF FIBRE• FIRST EQUILIBRIA TRANSFER OF DYE FROM SOLUTION TO
FIBRE SURFACE• SECOND EQUILIBRIA PENETRATION OF DYE FROM FIBRE
SURFACE TO FIBRE INTERIOR• DISTURBANCE IN FIRST EQUILIBRIA• PROCESS CONTINUE TILL THREE PHASES ARE IN EQUILIBRIUM
DYE FIBRE INTERACTION
CLASSIFICATION OF ATTRACTIVE FORCES
ATTRACTIVE FORCES BETWEEN DYE AND FIBRE2. VAN DER WAAL’S FORCES OR DISPERSION FORCES
4. HYDROGEN BONDS
6. ELECTROSTATIC ATTRACTION
8. CO-VALENT BOND
DYE-FIBRE INTERCTION
FORCES OF ATTRACTIONDYE CLASS FORCE OF ATTRACTION
CELLULOSIC (COTTON, JUTE, VISCOSE)DIRECT, VAT, SULPHUR VANDER WAAL, H-BONDSOLUBILIZED VATREACTIVE CO-VALENT BOND
WOOL, SILK, NYLONDIRECT, ACID, METAL IONIC OR ELECTROSTATICCOMPLEXREACTIVE IONIC/COVALENT
POLYESTERDISPERSE VANDER WAAL, H-BOND
ACRYLICCATIONIC INONIC OR ELECTROSTTIC
FORCE OF ATTRACTION AND WASH FASTNESS
• DYED FIBRE MUST MEET CERTAIN FASTNESS REQUIREMENT TO VARIOUS AGENCIES LIKE WASHING, LIGHT, RUBBING
• FASTNESS PROPERTY DEPENDS ON SEVERAL FACTORS• WASH FASTNESS DEPENDS ON • FORCE OF ATTRACTION BETWEEN DYE AND FIBRE• PHYSICAL STATE OF DYE INSIDE THE FIBRE• PHYSICAL STRUCTURE OF FIBRE
• BOND ENERGY• COVALENT BOND > ELECTROSTATIC BOND > H-BOND >
VANDER WAAL FORCE
• WASH FASTNESS• REACTIVE DYE > ACID, METAL COMPLEX, CATIONIC > DIRECT,
VAT, SULPHUR, DISPERSE
EXCEPTIONS
• VAT DYES ON COTTON• EXCELLENT WASH FASTNESS PROPERTY
REASONS• DYE INSIDE FIBRE WATER INSOLUBLE FORM• STATE OF DYE INSIDE FIBRE AGGREGATED (VERY HIGH
MOLECULAR WEIGHT)• BOTH THESE FACTORS LEAD TO VERY HIGH WASH
FASTNESS ON COTTON THOUGH WEAK FORCES OF DYE-FIBRE INTERACTION
DISPERSE DYES ON POLYESTER• DYE INSIDE FIBRE WATER INSOLUBLE FORM• VERY COMPACT PHYSICAL STRUCTURE OF FIBRE• DYE UNABLE TO DIFFUSE OUT UNDER WASHING CONDITIONS
100 YEARS OF CHRONOLOGICAL DEVELOPMENTS OF SYNTHEIC DYES
• 1856 FIRST SYNTHETIC DYE (PURPLE ), PERKIN• 1858 DISCOVERY OF THE PROCESS OF DIAZOTIZATION
AND COUPLING, PETER GREISS• 1859 MAGENTA DYE, FRENCH CHEMIST VERGUIN• 1862 FIRST SULPHONATED DYE• 1863 ANILINE BLACK, NICHOLSON• 1880 IN SITU AZOIC COLOUR FORMATION, READ
HOLLIDAY• 1884 FIRST DIRECT DYE, CONGO RED, BOTTIGER• 1893 FIRST SULPHUR DYE• 1897 SYNTHETIC INDIGO• 1890 METAL COMPLEX DYE• 1901 VAT DYE• 1922 DISPERSE DYE• 1956 REACTIVE DYE
NATURAL DYES BEFORE 1856 ABOUT 100SYNTHETIC DYES TODAY 2000-3000
DYEING METHODS
BATCHWISE OR EXHAUST DYEING• FIBRE• YARN • FABRIC
SEMI-CONTINUOUS DYEING• FABRIC
CONTINUOUS DYEING• FABRIC• YARN IN WARP SHEET FORM (INDIGO DYEING FOR
DENIM)
EXHAUST DYEING
MATERIAL TO LIQUOR RATIO (M:L RATIO)• VOLUME OF WATER TAKEN IN RELATION TO WEIGHT OF
MATERIAL (FIBRE, YARN OR FABRIC)e.g. M:L :: 1:10 MEANS FOR 1 kg OF TEXTILE MATERIAL 10 LITRES OF WATER TAKEN FOR DYEING
% DYEBATH EXHAUSTION• AMOUNT OF DYE GONE FROM SOLUTION PHASE TO FIBRE
PHASE AT THE END OF DYEING PERIOD EXPRESSED IN TERMS OF %. IT IS A MEASURE OF DYE SUBSTANTIVITY. THE TERM IS MAINLY APPLICABLE TO BATCHWISE DYEING.
• % FIXATION: AMOUNT OF DYE FIXED (INTERACTED) WITH FIBRE AFTER WASHING/SOAPING.
% SHADE• AMOUNT OF DYE TAKEN FOR DYEING ON THE BASIS OF
WEIGHT OF MATERIAL• e.g. 2% SHADE MEANS 2 gm DYE TAKEN FOR DYEING 100 gm
MATERIAL i.e TEXTILE FIBRE, YARN OR FABRIC.
BATCHWISE DYEING• DYEING IN SMALL BATCHES, 100-300 kg FABRIC
FABRIC DYEING EQUIPMENTSDESIGNED ON THREE PRINCIPLES
FABRIC MOVING, DYE LIQUOR STATIONARY• JIGGER (FABRIC IN OPEN WIDTH FORM) • WINCH (FABRIC IN ROPE FORM)
FABRIC STATIONARY, DYE LIQUOR MOVING• BEAM DYEING MACHINE FOR DYEING POLYESTER OR
POLYESTER/COTTON BLENDS (FABRIC IN OPEN WIDTH)
BOTH FABRIC AND DYE LIQUOR MOVINGJET DYEING MACHINE (FABRIC IN ROPE FORM)
CONTINUOUS DYEING
PADDING• SATURATION OF FABRIC BY DYE SOLUTION AND SQUEEZING
THE EXCESS LIQUOR BY PRESSING BETWEEN SQUEEZ ROLLERS
• MACHINE: PADDING MANGLE• TERMS COMMON FOR CONTINUOUS DYEING OF FABRIC.
EXPRESSION• %INCREASE IN WEIGHT OF DRY FABRIC AFTER PADDING e.g.• DRY FABRIC WEIGHT 1kg• FABRIC WEIGHT AFTER PADDING 1.8 kg• INCREASE IN DRY FABRIC WEIGHT 0.8 kg• % INCREASE IN WEIGHT 80%• EXPRESSION 80%• HIGHER THE VALUE OF % EXPRESSION LESS IS LIQUOR
SQUEEZING BY PADDING MANGLE AND VICE VERSA
DYEING MACHINES
Fibre dyeing machine Hank dyeing machine
Cheese/Cone dyeing machine
Winch
Jet Dyeing
Beam dyeing Jigger
Padding mangles
Pad-batch (Semi continuous
Pad- steam-wash (Continuous)