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INTRODUCTION

what are reactive dyes

classification of reactive dyes

According to modes of control:

  • Reactive dyes are the dyes which react chemically with the textile substrate i.e. forming covalent bond with the substrate .
  • Reactive dyes can be applied to various textile substrate i.e.wool,silk,cotton,viscose,polyammide e.t.c.
  • Alkalie controllable.
  • Salt controllable.
  • Temperature contrllable.

VENDOR AND CHEMICAL CLASS F REACTIVE DYES

According to reactive systems

Properties of Reactive dyes

  • Tri-azinyl type ring system.
  • B-sulphatoethyl sulphone type.

reactive group

Vendor

Trade name

  • Solubility.
  • Substantivity.
  • React chemically.
  • varied reactivity.
  • fastness properties.
  • process application.
  • Remazol
  • synozol.
  • vivizol.
  • sumufix.
  • Dystar.
  • kisc and kisco.
  • Eksoy.
  • sumitomo.

vinyl sulphone group

CONCLUSION

DYE FIBRE CHEMISTRY

Basic dye-fiber reaction

BASIC STRUCTURE OF REACTIVE DYES

PROCESS FOLLOWED IN THE UNIT

synthesis of cynuric chloride

mono-chloro triazine dye

  • Adsorption.
  • Absorption.
  • Diffusion.
  • Fixation.
  • Semi-continuous process
  • Continuous process.

vinyl sulphone group

dry

batch roll

pad

  • Since 1956 still develo- pments are going on in reactive dye processing.
  • Important part of textile dyeing.
  • Becomes important to understand the chemistry and properties of reactive dyeing.

Reaction of dye with fiber and water

Reaction of cellulose with vinyl sulphone

mono-chloro tri azyne dye

pad

R

wash

D

  • Rate of hydrolysis.
  • Effect of alkalie.
  • Objective of dyeing.
  • percentage of dyeing.
  • procion and HE dyes shows this kind of property.

CL

  • Neucleophilic addition.
  • suitable for CPB.
  • Poor affinity towards cellulose.
  • Brilliant shade and good fastness properties.
  • Good fastness properties.

oH-

cellulose o-

R

steam

oH

O.cellulose

Chemistry involved in pad steam process

FACTORS AFFECTING REACTIVE DYES

  • Initial stage of dyeing.
  • One bath two-step process.
  • Rate of hydrolysis.
  • Bath stability.

REACTIVE DYES

  • Affinity.
  • liquor ratio.
  • Concentration of electolyte.
  • PH.
  • Dyeing temperature and reactivity.
  • Time of dyeing.
  • Nature of dyeing.

multifunctional

bi-functional

monofunctional

hetro-bifunctional

homo-bifunctional

factors affecting reactive dyes.

Affinity

Liquor ratio

PH during dyeing of reactive dyes

  • Liquor ratio has powerful effect on level dyeing.
  • low liquor ratio less chances of hydrolysis.
  • Therefore liquor ratio should be low as much as possible.
  • Chances of hydrolysis is low in case of continuos and semi continuos process.
  • Depends upon temperature and dwell time.
  • Optimum PH for reactive dyeing 10.8-11.
  • cold brand-soda ash.
  • Hot brand or vinyl sulphone-TSP or caustic.
  • Amount of alkalie depends upon the depth of shade and class of reactive dyes.
  • High affinity for H-E brand dyes.
  • Posses low affinity towards cotton because of hydrolysis.
  • Dyeing takes place with 70%reaction therefore soaping is essential.
  • for continuos dyeing less affinity of dyes are required to avoid tailing effect.

Dyeing temperature and reactivity

Exhaution and fixation curve for reactive dyeing

Time of dyeing

  • Dwell time of the process.
  • Pressure given during padding of dye liquor.
  • Speed of the fabric.
  • Concentration of the dye bath.
  • High temperature provides both substantivity as well as level dyeing properties.
  • Reactivity of dye can be increased by two means-

1.By increasing alkalinity.

2.By raising the temperature.

  • substantivity and affinity both can be manipulated by varying the temperature.

CHEMISTRY INVOLVED IN THE PROCESS OF REACTIVE DYEING

PRESENTATION BY R.J YADAV.

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