Reactive dye is mostly give even dyeing of cellulose materials in textile industry.
Helo, reders welcome to “textilesgreen.in” today I m going to explain about reactive dye, reactive dyeing process, properties, classification and types.
Let’s get started,
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, silk. reactive dye make a proper covalent linkage with fibre.
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.
Reactive dye properties
1. Reactive dyes are soluble in water.
2. Reactive dyes are comparatively cheap and best.
3. Easy dyeing methods and it require less time for dyeing
4. It require low temperature for dyeing
5. Reactive dye having good perspiration fastness with rating 4-5.
6. Reactive dyes have very good wash fastness but has moderate
7. Reactive dyes have very good light fastness with rating 6.
8. reactive dyes are found in power, liquid and print past form.
9. Reactive dyes are anionic dyes, which are used for dyeing
cellulose, protein, and polyamide fibers
10. Dyes have stable electron arrangement and can protect the degrading effect of ultra-violet ray.
11. Easy methods
12. dyeing with low temperature.
13. Reactive dyes are also found in liquid and print paste form.
14. Cheap process
15. Make a covalent bond with the fibre and work as a integral part of the fibres.
16. reactive dyeing is gives positive effect on cellulose materials.
17. reactive dyes have more solubility in water.
18. light fastness is good
19. Washing fastness is also good.
20. rubbing fastness is moderate.
Here, i m going to explain about reactive dyes types.
1. Hot brand reactive dye
2. Cold brand reactive dye
3. Lower temperature reactive dyes
4. HE brand reactive dye
Chemicals is used in reactive dyeing
• soda ash
• sodium alginate
(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.
(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.
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.
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
• cotton ( yarn, knit, woven)
• natural fibre ( cellulose materials)
Reactive dyes classification
1. Reactivity system in dyeing
a)In case of reactive dyeing, there are two phases are work. Lower reactive dyes and medium reactive dyes. in case of reactive dyeing,
PH is maintained 11-12 by using Na2CO3 in dye bath.
b)in case of higher reactive dyes,
PH is maintained 10-11
by using Na2CO3 in dye bath.
2. temperature system of dyeing
a) cold brand
In case of cold brand reactive dye, Dyes contain reactive group of high reactivity. so dyeing can be done in lower temperature (320-360).
this type of dyes contain reactive group of moderate reactivity so dye is done in higher temperature then
that of cold brand dyes, in between 600-710C.
b) Hot brand
This type of dye contains reactive group of least reactivity. so high temperature is required for dyeing
i.e. 720-930 C
for example pricion H cibacron are hot brand dyes.
Reactive dyes machanism
Function of NaCl
Here, if you used NaCl as the electrolyte. this electrolyte is properly neutralize absorption. so when the textile material is introduces to dye liquor the dye is properly exhausted on to the fiber.
Fixation system of reactive dye
In case of reactive dyeing, The reactive group of dye is directly reacted with terminal OH or -NH2 group of fibre. and its gives strong covalent bond with the fibre.
Alkali is also very important role in reactive dyeing. Because alkali create proper PH in dye bath.
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
take required water in dye bath
Add soda ash in dye bath
After 10 mint add salt
Add materials in dye bath
Continue Dyeing at 40°C for – 1 hours
Stripping ia also necessary when uneven dyeing occurs.
In case of reactive dyeing
partial stripping is obtained by treating the dye fabric
with dilute acetic acid or formic acid. here, in case of stripping of reactive dyeing. temperature
is raised to 70-100C and treatment is continued until
shade is product of hydrolysis.
amount of acid used is
Glacial acetic acid – 5-10 parts
water – 1000 parts
In case of reactive dyeing
, we came to know the reactive dye are of the least reactivity because
they take more temperature and more time for dyeing.