What is reactive dye?
A water – soluble dye moderately substantive to cell-OH, protein and polyamide fibres and which is capable of reacting chemically with the fibre to form a covalent bond.
Or,
A dye, which is capable of reacting chemically with a substrate to form a covalent dye substrate linkage, is known as reactive dye. reactive dye can be dyed such as cotton, wool, and silk materials. reactive dye are make a proper covalent linkage with fibre. but there are different types of dyes are used in textile process house for colouration of textile goods. dyes have specific quality to dyed a particular textile fibre/materials.
For examples,
Reactive dye ;
This dyes have specific quality for colouration of specially cellulose (Cotton) materials. this dyes give good results on cotton materials. so, this dyes are used for colouration of cotton materials in textile process house.
Reactive dye is more suitable and profitable for cellulose materials. and it’s gives positive effect on cellulose materials. this is the reason that, reactive dyeing is windly used for dyeing of cellulose materials in textile industry. reactive dye have capability to makes covalent linkage with the fibre. and work as a integral part of fibre.
This covalent is formed between the dye molecules and the OH hydroxyl group of cellulosic fibers on between the dye molecules and the terminal -NH2 group of polymer.
Read More – Vat dyeing Process, dyeing of cotton with vat dye?
Reactive dye properties
Chemicals is used in reactive dyeing
Salt –
(a) Increases absorption.
(b) Decrease hydrolysis rate of dyes.
(c) help in extra energy for pantration.
(d) NaCl is widely used for reactive dyeing.
(e) improve affinity energy of dye.
PH –
(a) high PH is required in reactive dyeing because without high PH,
Dye will not fixed properly or permanently to the materials.
Sodium carbonate is used to maintain PH in case of reactive dyeing.
Time –
The role of time is very important in case of Dyeing because accurate or proper fixation is depand upon time. If increase of the time then fixation of dye will increase.
Its give good, wash fastness, rubbing fastness, light fastness, perspiration fastness.
Temp –
In case of cellulose materials, if used high temperature caused the cotton material to have no or poor ability to be dyed. It effects on cellulose materials. Cellulose materials is not gives good results.
And increase the ability to reaction mechanism during dyeing.
Two phases occur during dyeing
1. Exhaustion phase
( Proper dye absorption)
2. Fixation phases
(Proper dye reactions)
Shade is devlop with the help of salt and soda ash during dyeing
The role of salt and soda ash in reactive dyeing is very important because its gives proper shade
On dyed materials.
There are three types of shade is devlop with the help of salt and soda ash.
• Light shade
• medium shade
• deep shade
But it is depand upon quantity of salt and soda ash during dyeing.
Reactive dye having capacity to dyed textile goods such as,
• cotton ( yarn, knit, woven)
• natural fibre ( cellulose materials)
Read More – Direct dyeing Process, Dyeing of cotton with direct dye, eco – friendly direct dyes?
Reactive dyes classification
1. Reactivity system in dyeing
PH is maintained 11-12 by using Na2CO3 in dye bath.
PH is maintained 10-11
2. temperature system of dyeing
a) cold brand
this type of dyes contain reactive group of moderate reactivity so dye is done in higher temperature then
b) Hot brand
Reactive dyes machanism
Function of NaCl
Fixation system of reactive dye
In case of reactive dyeing, maintain PH with the help of alkali. If alkali is add in dye bath its creat proper PH in dye bath. In other words, it is also called dye fixing agent.
Washing system of reactive dye
If dyeing is completed then washing is must be required for textile materials because if unfixed dyes persent on the surface of the materials it is easily removed with the help of washing. and it’s also help in wash-fastness.
It is done with the help of hot washing and then again cold wash.and after this soaping is also required for textile materials.
Reactive dyeing methods
(a) Discontinuous methods
• Hot brand
• Cold brand
(b) Continuous methods
• Pad system methods
• Pad thermo fixation methods
(c) Semi – continuous methods
• pad roller methods
• pad jigger dyeing methods
recipe of cold brand reactive dyeing methods
• Dye – 1- 3%
• salt – 60 gm/c
• soda ash – 15 gm/c
• H2O – 10 times
• Temp – 40°C
• Time – 1 hours
Procedure
start
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take required water in dye bath
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Add soda ash in dye bath
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After 10 mint add salt
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Add materials in dye bath
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Continue Dyeing at 40°C for – 1 hours
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Wash
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Dry
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End
amount of acid used is
Conclusion:
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