Basics Of Color Perception And Measurement

Dyeing of Textiles

S.Periyasamy Dept. of Textile Technology PSG College of Technology

Dyeing Theory

Definition of Dye and Color Perception

Spectral Power Distribution of Sunlight

300

450

550

650

1000

150

Daylight Relative 100 Energy

50

0 400

500

600

Wavelength - Nanometers [nm]

700

Light Interaction with School Bus Paint Incident Light Diffuse Reflection

Specular Reflection

A Dye Molecule to Exhibit Color

Should have specific absorption and reflection characteristics in the visible region of the electromagnetic spectrum

Color Perception Color Perceived

Voilet

Wavelength (nm) Reflected 390 – 430

Blue

430 – 460

Blue-Green

460 – 500

Green

500 – 570

Yellow

570 – 590

Orange

590 – 610

Red

610 – 700

Dyeing

• Why not we apply by our Hand? • Why not we paint by brush?

Dyeing

Why to dissolve the dye in water and bother with the effluent treatment?

Dyeing

Uniformity!!!

Dyeing

Uniform application of dye molecule throughout the textile substrate diffusing through individual fibres How can we do it?

Dyeing • What actually dyeing?

happens

• Does the dye stay – in between the yarns? – in between the fibres?

during

Dyeing • No!!!

• Inside the Fibre! • Then, what is a Fibre?

Dyeing • Fibre – Unit of Matter Characterized by • Fineness • Flexibility • Strength • Temperature stability • Light resistance

• This is just a definition • What it is actually made of?

Dyeing • It is made of Polymer • What is a Polymer? – It is a Macromolecule

• Macromolecule?

– It means the size of a molecule

• What does it mean?

Dyeing • Simple molecule – Ethylene alcohol

• Macromolecule – Polyethylene

Relative length of the molecule

Very Large

Relative length of the molecule

Very Small

Dyeing • Then how would a fibre structure be?

10 µm

Textile Fibre Long Polymer Molecule Medium Polymer Molecule

Small Polymer Molecule

• How do dye molecules penetrate inside the fibres?

Dyeing Through

Adsorption & Diffusion

Dye Molecules

10 µm

Textile Fibre

Adsorption 10 µm

Textile Fibre

Diffusion 10 µm

Textile Fibre

10 µm

Textile Fibre

Diffusion & Fixation 10 µm

Dyed Textile Fibre

The

The Dyed Fibre

The

Fabric

Composed of the Yarns

Yarn

composed of the fibres

Dye – Fibre Combinations

Dyeing Major Textile Fibres • Cellulose fibres

– Cotton, linen, hemp, ramie, bamboo, rayon

• Protein fibres – Wool, Silk

• Synthetic Fibres

– Polyester, Nylon, Acrylic

• 50 % of World Consumption is Cotton – King of Fibres

• Cotton – Synonym of Textile

–White Gold

Dyeing Dyes for Textiles

• Till the end of 19th Century –Natural Dyes

• Later

–Synthetic Dyes

Dyeing Natural Dyes • Plant-based dyes such as woad (Isatis tinctoria), indigo, saffron, and madder were raised commercially and were important trade goods in the economies of Asia and Europe • Important Natural Dyes – Plant • • • • • • • • • •

Indigofera plant (blue) Madder root (red, pink, orange) Myrabolan fruit (yellow, green, black) Pomegranate peel (yellow) Weld herb (yellow) Catechu or Cutch tree (brown) Gamboge tree resin (dark mustard yellow) Himalayan rubhada root (yellow) Kamala tree (red) Larkspur plant (yellow)

– Animal • • • • •

Cochineal insect (red) Cow urine (Indian yellow) Lac insect (red, violet) Murex snail (purple) Cuttlefish (sepia brown)

Dyeing • Indigo is among the oldest dyes to be used for textile dyeing and printing • Indigo Indigofera tinctoria was used in India

– Earliest / Oldest major center for its production and processing

• The species was domesticated in India • Indigo remained a rare commodity in Europe throughout the Middle Ages. • Woad, a chemically identical dye derived from the plant Isatis tinctoria (Brassicaceae), was used instead. • In the late 15th century, the Portuguese explorer Vasco da Gama discovered a sea route to India – Indigo then was Imported from India

• Because of its high value as a trading commodity, indigo was often referred to as

blue gold

Procedure of Dyeing • Typically, the dye material is put in a pot of water and • Then the textiles to be dyed are added to the pot, which is heated and stirred until the color is transferred. • Most textiles are "yarn-dyed" or "piece-dyed" after weaving • Many natural dyes require the use of chemicals called mordants to bind the dye to the textile fibres – Tannin from oak galls, salt, natural alum, vinegar, and ammonia from stale urine were used by early dyers

– Many mordants, and some dyes themselves, produce strong odors

Synthetic Dyes • Dyes are Classified based on – Chemistry • • • • • • • • •

Azo Stilbene Diphenyl Methane Quinoline Thiazole Azine Sulphur Indigoid Anthraquinone

– Application • • • • • • • •

Direct Dye Reactive Dyes Vat Disperse Dyes Acid Basic Mordant Dyes Azoic Dyes

Dye Fibre Combinations • Cotton (Cellulosics) – – – –

Reactive Vat Sulphur Direct

• Silk

– Acid – Reactive – Complex Dyes

• Wool

– Acid – Reactive – Complex Dyes

• Polyester

– Disperse

• Nylon

– Disperse – Reactive – Acid

• Acrylic

– Disperse – Basic

Most widely used Dyes

Reactive Vat Sulphur Disperse As because Cotton & Polyester are the Dominant Fibres

Dyeing Principles

• Exhaust Principle

• Dye actively get exhausted from bath to the fabric

Dyeing Principles

• Padding Principle

• Dye molecules are passively deposited over the fabric and made to penetrate through squeezing

Dyeing technology • The goal of every dyeing is – A colored textile in the desired shade – Homogeneous in hue and depth of shade – Produced by an economic process and which

– Exhibits satisfactory fastness properties in the finished state

Typical Dyeing Cycle – Reactive Dyes • Dye : 2% • NaCl : 30 gpl • Na2CO3 : 15 gpl • Temp : 60 - 100 °C • Time :1h

Typical Dyeing Cycle – Disperse Dyes

Sequence of Operations in

Woven Dyeing

Sequence of Operations in

Woven Dyeing

• Dyeing Auxiliaries

– Wetting agent – Detergent – Sequestering agent – Leveling agent – Anti foaming agent – Dispersing agent – Anti creasing agent – Carrier – Exhausting Agents – Fixing Agents – Retarding Agents

Quality Parameter of Dyed Textiles

Quality Parameter of Dyed Textiles • Fastness

– Ability to withstand fading of dyes from fabrics due to various • Commercial factors – – – – – –

Washing Perspiration Rubbing Sublimation Chlorine Solvents

• Environmental factors

– Light – Microbe – Weather / Atmosphere / Ozone

• Cross-Staining during Washing

Quality Parameter of Dyed Textiles • Shade Matching

– Computer Color Matching systems

Quality Parameter of Dyed Textiles Uniform Dyeing Uneven Dyeing

Spots

Dye Spots Patchy Dyeing

Pin Marks

Poorly adjusted stenter pin

Holes

by defective machine elements

Stain

Excessive oil, dirt

Dyeing Machines

Package Yarn Dyeing Machine (Vertical Type):

Package Yarn Dyeing Machine (Horizontal Type):

Winch Dyeing Machine:

Figure: Roto Master (Thies Winch Dyeing Machine)

Figure: Schematic view Roto Master (Thies Winch Dyeing Machine)

Technical Details:

Jigger Dyeing Machine:

Figure: Thies Jigger

Feature: Atmospheric (up to 98°C) & HT Economical dyeing & Low liquor ratio PLC Controlled Fabric tension: 50-800 N Fabric speed: 10-150 m/min Fabric width: max. 5400 mm Roller width: max. 5600 mm

Sanforizing Machine:

OWER-SHRINK Sanforizing machine (Brückner)

Airflow Dyeing Machine

Garment Dyeing

Why Garment dyeing? • Traditionally, garments are constructed from fabrics that are predyed (piece dyed) before the actual cutting and sewing. • The advantage of this process is the cost effectiveness of mass producing identical garments of particular colors. • A major drawback with this approach is the risk associated with carrying a large inventory of a particular style or color in today's dynamic market.

Which type of Products

• Pants, pullovers, t-shirts, jeans, sweaters, dresses, bathrobes, casual jackets, shirts, skirts, hosieries

Requirements of Garment Dyeing Machines

• Should be gentle • Should dye uniformly • Should be defects

free

• Should not accessories

affect

from

machine

the

garment

Garment Dyeing Machines

Garment Dyeing Machines

Advantages

• Quick response and rapid turnaround • Flexibility towards dye shades and finishes • Flexibility of lot size • Flexibility of items to be dyed • Comparatively less rejection • Low inventory • Less capital investments • Fancy effects

Disadvantages • Poor appearance

• Poor reproducibility of shades • Special care in the selection of fittings • More material handling

Eco-Friendly Dyes and Chemicals

Problems with the Present Dyes • Dyes that

– Release banned amines – Require formaldehyde fixing agents – Has metals in its structure

• Use of large quantities of auxiliaries, e.g. – – – –

NaCl Na2CO3 Surfactants Sodium sulfate, softeners

acids,

alkalis,

sequesterents,

• Release of large quantities of polluted water • Pentachlorophenol – in sizing • Formaldehyde – Dye fixing agent and finishing agent • Brominated flame retardants, etc.

List of Banned Amines

Eco-friendly approach

• Select dyes that

– Do not release banned amines – Do not contain metals – Do not require any fixing treatments – Use high exhausting dyes

• Use of alternative chemicals and methods like • Plasma processing processing • Foam applications, etc

–

As

dry

Thank you