INTRODUCTION
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
- Adsorption.
- Absorption.
- Diffusion.
- Fixation.
- 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
- Rate of hydrolysis.
- Effect of alkalie.
- Objective of dyeing.
- percentage of dyeing.
- procion and HE dyes shows this kind of property.
- Neucleophilic addition.
- suitable for CPB.
- Poor affinity towards cellulose.
- Brilliant shade and good fastness properties.
- Good fastness properties.
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.
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.