Introduction To Wet Processing-dyeing Printing Lecture

TEX 110 DYEING AND PRINTING

BRIEF COURSE OUTLINE Introduction Process Flows & Substrates

Water & Effluents

Pretreatment Singeing

Desizing

Scouring

Bleaching

Mercerization

Coloration Color & Colorants

Dyeing

Printing

Finishing Finishing Types

Evaluation of Finishing

EVALUATION SCHEME

True perfection is an unreachable aim, but however is worth to be pursued with all our strength

Principles of Textile Coloration,, SDC, UK, 2001 Coloration LWC Miles, Textile Printing, Revised 2nd Ed., SDC, UK, 2003 D Heywood, Textile Finishing, SDC, UK, 2003

Readings

AD Broadbent, Basic

Web

Textbook

ACADEMIC RESOURCES EPG Gohl & LD Vilensky Vilensky,, Textile Science, 2nd Ed. Longman, India, 1987

Textile Terms and Definitions, 11th Ed. The

Textile Institute, UK, 2002 RM Christie, Environmental

Aspects of Textile Dyeing, Dyeing, Woodhead,, UK, 2007 Woodhead

www.pdfcoke.com www.e--textile.org www.e

INTRODUCTION TO WET PROCESSING

TEXTILE MANUFACTURING PROCESS

Fabrication/ Dry Processing

Wet Processing

TEXTILE RAW MATERIALS

Manufacturing process starts with the production or harvesting of raw fiber. Fibers used in textile processing can be harvested from natural sources or manufactured from natural or synthetic polymer.

GLOBAL FIBER PRODUCTION BY TYPE AND ENDEND-USE

GLOBAL FIBER PRODUCTION BY TYPE AND ENDEND-USE

TEXTILE MANUFACTURING SEQUENCE Fiber

Yarn Formation Fabric Formation

• Staple Yarn • Filament Yarn • Grey Woven Fabric • Grey Knit Fabric

Wet Processing

• Finished Woven Fabric • Finished Knit Fabric

End-Product EndManufacture

• Apparel • Home Tex, Technical Tex

Fibers usually undergo four main processing stages in textile mills. In addition to apparel as endend-product, home or technical textile are also produced within these stages but in different ways.

WET PROCESSING OF TEXTILES

The third stage involve wet operations which consume large amount of water and chemicals and also generates enormous amount of wastewater or effluents.

WET PROCESSING STAGES

PROCESSING ROUTE BASED ON SUBSTRATE

WET PROCESSING OF COTTON Staple

Yarn

Fabric

Singeing & Mercerization

Singeing & Desizing

Scour & Bleach

Scour & Bleach

Yarn Dyeing

Mercerization Dyeing &/or Printing

Not For Knits

Finishing

WET PROCESSING OF POLYESTER Staple or Filament Yarn

Woven/Knit Fabric

Scour & Dyeing

Scouring

Presetting

Dyeing &/or Printing

Finishing

WET PROCESSING OF POLYESTER

WET PROCESSING TERMINOLOGY

A series of operations that prepare the textile product for subsequent finishing treatments such as dyeing, printing and finishing. The main operations are singeing, desizing, scouring, bleaching & mercerization.

WET PROCESSING TERMINOLOGY

WET PROCESSING TERMINOLOGY

The process of burning protruding fibers to deliver a smooth fabric surface. An oxidizing flame that does not leave any sooty residue on fibers is used and then passed through a quenching unit. Desizing units are usually used in conjunction with the singeing process.

WET PROCESSING TERMINOLOGY

This treatment is carried out on woven fabrics to remove sizing ingredients from the warp so that the fabric absorb the liquor of subsequent processes homogenously. Enzymes are used to biologically degrade starch and transform it into water soluble byby-products.

WET PROCESSING TERMINOLOGY

The process of removing impurities such as wax, oil, fat from fiber to render it absorbent is called scouring. This is carried out in alkaline conditions (with NaOH NaOH)) under high pressure and temperature (above 100 oC) in presence of detergent, sequestering agent and wetting agent.

WET PROCESSING TERMINOLOGY

The removal of natural coloring matters from fiber to achieve whiteness is called bleaching. The most common bleaching agent is stabilized alkaline solution of hydrogen peroxide. After treatment, the bleaching agent must be removed by washing or through the use of enzyme.

WET PROCESSING TERMINOLOGY

The treatment of cotton with strongly alkaline solution to improve tensile strength, luster and dye uptake is called mercerization. It is usually carried out after scouring and/or bleaching in cold condition.

WET PROCESSING TERMINOLOGY

WET PROCESSING TERMINOLOGY

Dyeing is employed to give an allall-over shade to the fabric. In dyeing process, dye molecules come into contact with fiber surface, form a thin layer and diffuse into it. Dyeing may be carried out in batch or semisemicontinuous or continuous technique and in fiber or yarn or fabric state.

WET PROCESSING TERMINOLOGY

WET PROCESSING TERMINOLOGY

Printing is a process by which colored patterns are produced on the fabric. The color is applied to the fabric according to planned design and then treated with heat, steam or chemicals to fix the color on the fabric. Finally the fabric is washed to remove any excess paste and then dried.

WET PROCESSING TERMINOLOGY

WET PROCESSING TERMINOLOGY

It includes the final operations necessary for making the textile attractive and suitable for endend-use. It imparts the final aesthetic, chemical and mechanical properties to the fabric as per endend-use requirements. Examples include drying, softening, calendaring etc.

WET PROCESSING TERMINOLOGY