INTRODUCTION TO TEXTILE INTRODUCTION TO TEXTILE WET PROCESSING WET PROCESSING

T.KARTHIKEYAN

WHY WET PROCESSING?WHY WET PROCESSING?TO IMPART WEARING

COMFORTABILITY

TO IMPART APPEARANCE

TO IMPART HANDLE

TYPES OF WET TYPES OF WET PROCESSINGPROCESSINGCONTINIOUS PROCESS

SEMI CONTINOUS PROCESS

BATCH PROCESS

PROCESS SEQUENCE PROCESS SEQUENCE (COTTON)(COTTON)

GI STICHING SHEARING & CROPPING SINGEING (OPTION) DESIZING SCOURING BLEACHING MERCERIZING DYEING FINISHING

FIBER BLENDSFIBER BLENDS

To facilitate processingTo improve properties Abrasion resistance Strength Absorbency Bulk and warmth Hand Dimensional stability Resistance to wrinkling

To produce multi-colored fabricsTo reduce costs

Objectives in PreparationObjectives in Preparation

Preparation is the process of preparing fiber, yarn or fabric for subsequent steps such as dyeing, printing, finishing, and/or special processes for apparel and non-apparel end uses. The primary function of preparation is to

remove impurities that will interfere with overall processing through all dyeing and finishing functions

Objectives in PreparationObjectives in PreparationProduce a Substrate that Has:Uniform extraction of impurities, such as

sizes, seed husks, pectin's, waxes, chemicals, catalytic substances, etc. Uniform standards of whiteUniformly swollen fibers for transport of

dyes and chemicals (absorption)Minimal fiber damageRapid imbibing of waterA constant pHUniform residual moisture content

Preparation ProcessesPreparation ProcessesSingeingDesizingScouringBleachingEnzyme Processes (cellulosics only)Mercerizing (cotton only)Heatsetting (synthetics only)

Grey inspectionGrey inspectionPerching - Visual inspection and marking

the areas of flaws, stain,knots etc,. Burling - Removal of yarn knots and

other imperfections.Mending - Actual repair of imperfections.Means - By manually or laser beam.

10

INSPECTION MACHINEINSPECTION MACHINE(WOVEN)(WOVEN)

INSPECTION INSPECTION MACHINEMACHINE(KNITTED)(KNITTED)

11

INSPECTION INSPECTION MACHINEMACHINE(WOVEN)(WOVEN)

SHEARING & CROPPINGSHEARING & CROPPINGREMOVAL OF PROTRUDING YARNS ON THE RAW MATERIAL

SHEARING -- RAISING OF PROTRUDING YARNS

CROPPING -- CUTTING OF PROTRUDING YARNS

SingeingSingeingBurning off of the short fiber ends on

the surface of fabrics to produce smooth fabric appearance and minimize pilling.

The Process

y Fabric is passed by gas flames at high speed (up to 250 yd/min)

y Fabric may be passed over Heated plates or rolls Heated wires

WATER REQUIREMENTWATER REQUIREMENTCLEAR & ODOURLESSCHLORINE FREELOW HARDNESS(40PPM)

DESIZINGDESIZING

REMOVAL OF SIZING CHEMICALS

METHODS:ACID STEEPING METHOD

ENZYME STEEPING METHOD

OXIDATION METHOD

ENZYMATIC DESIZINGENZYMATIC DESIZING

pH 5.5 to 6.5Temperature - 60CBacterial enzyme 1.5 2 g/lCommon salt 1 2 g/lWetting agent 1 2 g/l

The Scouring ProcessThe Scouring ProcessPurposeDestruction and/or removal of

oils, fats, and waxes from textile fibers.

Why?These impurities inhibit:xRapid wetting of fibersxAbsorbency of fibersxAbsorption of dye and chemical

solutions

SCOURINGSCOURING--Techniques for Techniques for RemovalRemoval

Saponification (Fats and Oils) Hot Sodium Hydroxide

Emulsification Surfactants Extraction Organic Solvents

SCOURING PROCESSSCOURING PROCESS

CAUSTIC BOILINGSOLVENT ASSISTED

CAUSTIC BOILING

SOAP-SODA BOILINGENZYMATIC SCOURING

SCOURING RECIPESCOURING RECIPESodium hydroxide 2-3%Wetting Agent 0.5%Sequestering Agent 0.03%

SCOURING SYNTHETICSSCOURING SYNTHETICS

These fibers may contain spinning, knitting, or coning oils

Many of these oils are self-emulsifiable

They disperse in water without use of surfactant

For solid fabrics, may process at 160 degrees F with:0.2 % Surfactant

BLEACHINGBLEACHING Two Main Bleaching SystemsTwo Main Bleaching Systems

Chlorine Chlorine Peroxide Peroxide

GoalsGoals Complete removal of nonComplete removal of non--fibrous matterfibrous matter Extraction of colored impurities of indeterminate typeExtraction of colored impurities of indeterminate type Hydrolysis, oxidation, and removal of residual sizeHydrolysis, oxidation, and removal of residual size Achievement of requisite degree of whiteness with the least Achievement of requisite degree of whiteness with the least

possible damage to the fiberpossible damage to the fiber Improved absorbencyImproved absorbency

ProblemsProblems Leftover BleachLeftover Bleach Yellowing (strength loss)Yellowing (strength loss) HolesHoles

BLEACHING PROCESSBLEACHING PROCESS

OBJECTIVES:Destruction of color impurities in

fibers to produce a uniform bright white fabric that is free of motesUsually involves oxidation of the

color impuritiesCan involve reduction of the color

impurities

BLEACHING PROCESSBLEACHING PROCESS

Major Bleaching Agents Oxidative Bleachesx Sodium Hypochlorite (NaOCl)x Hydrogen Peroxide (H2O2)x Sodium Chlorite (NaClO2)

Other Peroxygensx Sodium Perborate (NaBO2H2O23H2O)x Sodium Percarbonate (2Na2CO33H2O2)x Peracetic Acid (CH3COOH)

Reductive Bleachesx Sulfur Dioxide (SO2) and its derivativesx Sodium Hydrosulfite

Hydrogen PeroxideHydrogen PeroxideRecipey Hydrogen peroxide 0.5 - 0.8%y Sodium silicate 0.5 - 1.0% y Sodium carbonate 0.5 - 1.0%y Sequesting agent 0.02 0.05%y pH 9.5 10.5

Chlorine bleachingChlorine bleaching Low priced bleachWhite effect not completely satisfactory Slight danger of damage to Cellulosic fibres;

great danger to Synthetic fibresCorrosion resistant equipment is necessaryUnpleasant odours in the factoryContinuous and discontinuous processes are

possible Stabilization is by adjusting the pH value

Peroxide BleachingPeroxide BleachingTolerable costly bleachWhite effect is good and permanentSlight danger of damage to Cellulose and

Synthetic fibresNo danger of equipment corrosionNo unpleasant odoursStabilization plays a decisive role

BLEACHING PROCESSBLEACHING PROCESS

Parameters Affecting Bleaching Bleach concentration Time of process Temperature of process pH of bleach solution

1, 2, and 3 are interrelated pH is important in controlling concentration

of active bleaching agent Bleaching also degrades fiber.

Must control conditions to Maximize whitening Minimize fiber degradation

CONTINOUS BLEACHING CONTINOUS BLEACHING PROCESSPROCESS

CONTINOUS PROCESSCONTINOUS PROCESS

CONTINOUS PROCESS

ROPE SCOUR & BLEACH ROPE SCOUR & BLEACH RANGERANGE

COMBINATION HYDROGEN PEROXIDE & CAUSTIC SODA OR SODA ASH

MAINLY FOR KNITS MAINLY FOR BLENDS & SYNTHETICS FOR MEDIUM SHADES ON 100%

COTTON

COMBINED SCOURING & COMBINED SCOURING & BLEACHINGBLEACHING

MERCERIZINGMERCERIZING(FOR COTTON (FOR COTTON & ITS BLENDS)& ITS BLENDS)

DEFINITION:

Mercerization is the treatment of cotton with a strong caustic solution. This is performed on yarn or fabric, both woven and knits. Tension may or may not be used.

Purpose:Improves absorption, increase in dye affinity and yieldImproves breaking strength (improved up to 20%)Improves dimensional stabilityImproves chemical reactivityImproves fabric smoothnessCovers immature cotton fibersLuster is increased

When to Mercerize Greige Any step during preparation After bleaching

Observable Changes Deconvolution Fibers become rounder, smoother, and more

uniform

Mercerization Processing Mercerization Processing ParametersParameters

Caustic concentration48-54oTw (25-30%) ; (Lower-Less luster, Higher-No effect)

Wetting agent (Penetrant) Necessary for grey mercerization Stable and effective in strong alkali

Temperature 70-100oF Wet Pickup 100% WPU ;( 30 seconds ; (< 30 sec. Incomplete mercerization, > 30 sec. No effect) Framing ;Frame speed no more than 5% greater than padder Washing Caustic solution concentration in fabric should be reduced to less than 5% on frame

If not Shrinkage Low luster

Fabric should not shrink as it comes off the frame Rinsing

Caustic should be thoroughly rinsed Neutralize in weak acid solution

Unmercerized vs. Mercerized Unmercerized vs. Mercerized FibersFibers

MERCERISING RANGELINE DIAGRAME

MERCERISING RANGE

HEATSETTING HEATSETTING Applying High Temperature (350-400oF) above Tgto

stabilize fabric.

Purpose: Establishes fabric memory Polyester, nylon, triacetate Not rayon, cotton, or acrylics

Problems: Shade change (before or after dyeing) Yellowing Width variation Side-center-side heat history variation Excessive moisture in fabric prevents fiber from

reaching heat-setting temperatures

Factors influencing heatset: Time Temperature Moisture Tension

Heatsetting examples: Resistance to wrinkling during water Resistance to shrinkage during washing and dry

cleaning Provides wash-wear properties Reduces pilling tendency Provides permanent pleats and creases

COLORCOLOR

PSYCHOPHYSICAL PHENOMENAELECTROMAGNETIC RADIATIONDUE TO PHOTO-CHEMICAL REACTIONS IN THE EYEVISUAL EXPERIENCE INDEPENDENT OF SHAPE OR DURATION

COLORCOLOR

REQUIREMENTS LIGHT SOURCE OBJECT OBSERVER

OBJECT COLOROBJECT COLOR

Mixing of Colors Mixing of Colors AdditiveAdditive

Mixing of ColorsMixing of Colors--SubtractiveSubtractive

METAMERISMMETAMERISM

Objects which appear to match or evoke the same color under at least one light source, but have different spectral reflectance curves appear mismatched under a different light source are metameric objects or exhibit metamerism.

Variations: Illuminant metamerism Observer metamerism Geometric metamerism Instrument metamerism

COLOR MEASUREMENTCOLOR MEASUREMENT

COLORIMETER-MEASURES THE AMOUNT OF VISUAL RED, GREEN, AND BLUE COMPONENTS REFLECTED FROM A PARTICULAR COLOR SAMPLE. TRI-STIMULUS VALUES, X, Y, Z REVEALS METAMERISM

SPECTROPHOTOMETER-GIVES NON-METAMERIC COLOR MATCHES-SPECTRAL REFLECTANCE

COLOR EYE-COMBINATION OF A COLORIMETER AND A SPECTROPHOTOMETER

COMPUTER COLOR MATCHINGCOMPUTER COLOR MATCHING

Reduce the number of production addsMatch colors at lower costsProvide consistent distribution of

shadesControl dye inventory levelsMonitor dye quality

Sources of Color VariationsSources of Color Variations

y Raw Materials Substrate (fiber, yarn, or fabric) Preparation of substrate Dyes Dyeing Assistants (chemical auxiliaries) Water

y Processing Time Temperature Machine speed Steam Quality Liquor Ratio Etc. (including subsequent processing, i.e. finishing)

DYEINGDYEINGMaterials Dyed

y Fibers Stock dyeing Dope dyeing

y Yarns Skein dyeing Package dyeing Beam dyeing

y Fabrics Piece dyeing Printing Roller application, resist, discharge Flat Screen Rotary Tie Dyeing

y Garments Garment dyeing

DYEINGDYEING

OBJECTIVES OF DYEING SHADE FASTNESS PROPERTIES COST

y FACTORS THAT AFFECT THE APPARENT SHADE LIGHT SOURCE SURROUNDINGS AGE OF OBSERVER EMOTIONS EYE FATIGUE FABRIC SURFACE

y KEYS TO GOOD QUALITY CONSISTENCY UNIFORMITY KNITS-LOW TENSION WOVENS-PENETRATION

TYPES OF DYEING SYSTEMSTYPES OF DYEING SYSTEMS

Aqueous-in waterNon-aqueous-in organic solventsSublimation-thermosol, heat

transfer

DYEING DYEING -- REQUIREMENTSREQUIREMENTS

ABSORBENCY SHOULD BE BELOW 3 SECONDS.

pH SHOULD BE NEUTRAL ( 7.0 )

WHITENESS INDEX SHOULD BE ABOVE 50

Factors Which Influence DyeingFactors Which Influence Dyeing

Liquor ratioMachine parametersFiber structure and compositionTemperatureDye purityDyebath conditions

Causes of NonCauses of Non--Level DyeingsLevel Dyeings

Too little agitationToo low liquor ratioRate of dyeing too highUneven pick-up in paddingUneven moisture penetrationMigration during dyeingChemical or mechanical barre in the

fabricDyebath instabilityConstruction

FACTORS IN SELECTING FACTORS IN SELECTING DYESDYES

EconomyShade (brightness or dullness)Fastness requirementsLevel dyeing propertiesBarre controlEase of dispersion/dissolvingDustingEnvironmental issues

Different Types of DyeingDifferent Types of Dyeing

Fiber: Method where bundles of cotton fibers are typically dyed in baskets. Dyed fibers are typically blended in yarn manufacturing to obtain the final shade. This is necessary for specific textile styles.

Yarn: Technique where yarn is dyed on packages in skeins, hanks, or beams. This method is necessary to produce stripes, plaids, or jacquard patterns.

Fabric: Method where fabrics are dyed using batch machines, pad-batch systems, or continuous ranges. The specific process chosen depends on fabric style, production requirements, and other quality/cost considerations. Textile printing is a specialized form of fabric dyeing. This is the most versatile and highest productivity method.

Garment: Dyeing process where sewn garments are dyed in batch machines. This technique has both advantages, disadvantages, and limitations because of the garment form. This method allows for the quickest response to changes in the color market.

Four Steps in the Dyeing ProcessFour Steps in the Dyeing Process

Exhaustion DyeingExhaustion Dyeing

Purpose of Dyeing MachineryPurpose of Dyeing Machinery

Batch Dyeingy Move the dye liquor through the goodsy Move the goods through the dye liquorContinuous dyeingy Apply a concentrated solution of dye

evenly uniformly to the goods with thorough penetration

FIBRE/YARN PROCESSINGFIBRE/YARN PROCESSING

Package DyeingPackage Dyeing

FIBRE/YARN PROCESSINGFIBRE/YARN PROCESSING

FOR KNITTED FOR KNITTED

FABRIC PROCESSINGFABRIC PROCESSING

JET DYEINGJET DYEING

SOFT OVER FLOW DYEING MACHINELINE DIAGRAME

SOFTFLOW M/CSOFTFLOW M/C

CLOSED JIGGER

Continuous DyeingContinuous Dyeing

Definition-a dyeing method where concentrated dye solution is applied across the full width of the fabric by padding or foam application continually followed by subsequent fixation of the dye by chemical or thermal means.

Pad/Continuous DyeingPad/Continuous Dyeing

Long runs-High speedUniform pad pressureConstant and accurate bath

concentration% Wet pickup

Reactive DyesReactive DyesProperties y Soluble in watery Two types

HOT BRAND COLD BRAND

y Excellent washfastness-dye chemically bonded to cellulose

y Good lightfastnessy Fair-good fastness to bleaching (not with

chlorine)y Fair-good crockfastness

Disperse DyesDisperse DyesPropertiesInsoluble in waterWater dispersibleNonionicDyes all synthetic fibersSublime when heatedStains cellulose fibersStains protein fibers

Batch Dyeing PolyesterBatch Dyeing Polyester

Thermosol Dyeing of PolyesterThermosol Dyeing of Polyester

Important Factors in Dyeing Important Factors in Dyeing BlendsBlends

Dye selectivityDyebath conditions

Dye auxiliaries Dyebath temperature Stress on fabric

Dyestuff blockage Retarding agents Dye-molecule blockage

Determination on dyeing on various fibers

Fiber DyeingFiber DyeingPositivesy Novel dye effectswithin yarnwithin fabricy Blends of fiber with cross dyeing capability

different fiber typesdifferent types of cotton

y Negativesy Highest dye costsy Expensive colored wastey Small lot dyeing variabilityy Impacts yarn spinning qualityy short fiber flyy lower spinning efficiencyy Fiber contaminantsy Blending, net dyeing, for shade

Yarn DyeingYarn Dyeing Positivesy Novel color effects

stripes, plaidsjacquards

y Smoother initial fabric surfacey High color quality for pattern effectsy Multiple styling possibilities for 100% cotton fabrics

Negativesy High dyeing costsy Color variability within and between yarnsy Expensive colored wastey Colored fly contamination in knittingy High inventory costsy Somewhat count limited

Fabric DyeingFabric Dyeing Positivesy Versatile, multiple fabric types

knits,wovens &non-conventionaly High productions, economy of scaley High quality of colorationy Low costs, non-colored wastey Good use of water, energy, and chemicals Negativesy Solid colors for 100% cotton fabricsy No true heathersy Fuzzy fabric surfacey Increased fabric shrinkage and distortiony Greater chance of color defectsstreaksblotchesrope

marks

Garment DyeingGarment Dyeingy Positivesy Quick response to markety Just-in-time processingy Possible garment finishing at lower costsy Minimum garment shrinkagey Lower total waste

y Negativesy Lower productivityy Issues with the garment

mixed panelspuckered seamssurface abrasionuniform dye penetration

y Stricter requirements for garment assemblyy Ultimate preparation requirementsy Higher overall dyeing costs

THANK U