Here the dye contains a reactive group and this reactive group makes covalent bond with the fibre polymer and act as an integral part of fibre. This covalent bond is formed between the dye molecules and the terminal –OH (hydroxyl) group of cellulosic fibres on between the dye molecules and the terminal –NH₂ (amino) group of polyamide or wool fibres. Reactive dyes forms covalent bond with fibre polymer and thus attach itself with fibre. It is now a days mostly used for dyeing cotton yarn and fabric. It is a cationic dye. Cold brand reactive dyes have higher reactivity.

Reaction:

D-SO₂-CH₂-CH₂-OSO₃Na +OH-cell ⇒ D-SO₂-CH₂-CH₂-O-cell + NaHSO₃

D-SO₂-CH₂-CH₂-OSO₃Na + NH₂– wool ⇒ D-SO₂-CH₂-CH₂-NH-Wool + NaHSO₃

Here,

D= dye part.
Wool = wool polymer.
Cell = cellulosic polymer

Cold brand reactive dye:

These types of dyes contain reactive group of high reactivity. So dyeing can be done in lower temperature i.e. 32⁰-60⁰C.

For example: PROCION M, LIVAFIX E.

Recipe:

Dye ( ) = 1%
Wetting agent = 1 g/L
Soda ash = 20 g/L
Common Salt = 30 g/L
M: L = 1:20
P^H= 6-7 for exhaustion = 11± 0.5 for fixation
Time =35 ‘ -45 ‘ for exhaustion = 40 ‘ -60 ‘ for fixation.
Temperature = 40⁰ -50⁰C for exhaustion = 50⁰-60⁰C for fixation.

Calculation:

Material weight= 14 gm.
Total liquor = 280 c.c.
Required Dye = Meterial weight x shade %
Dye = 14 x 1% = .14 gm
Amount of wetting agent =(1 x 280 ) / 1000 = 0.28 c.c.
Amount of sequestering agent = (1 x 280 ) / 1000 = 0.28 c.c.
Amount of leveling agent = (1 x 280 ) / 1000 = 0.28 c.c.
Amount of soda =(10 x 280 ) / 1000 = 2.8 c.c.
Amount of salt = (30 x 280 ) / 1000 = 8.4 c.c.

Dyeing Curve:

Procedure:

According to dyeing curve at first auxiliaries and water are added in the dye bath.
And it is kept for 5 minute.
Then material, dye is added respectively.
Then after 10 minutes salt is added.
After adding salt dye bath is heated to 40⁰-50⁰C kept for 20-30 minutes. This is the exhaustion period of dyeing.
Then alkali is added in the dye bath.
After adding alkali the dye bath is heated for 40-60 minute at 50-60⁰ This is the fixation period.

After treatment:

After dyeing operation is completed the dye material is put into a bath containing 1% stock solution of acetic acid. This operation is done for neutralizing the fabric. This operation is performed at 60⁰C for 10 minutes.
Secondly the material is treated with a 1g/L soap solution, which removes the unfixed dye from fabric surface, and makes the surface clean.
Thirdly material is treated with a hot water bath.
Fourthly material is treated with a cold-water bath.
Finally the material is dried in a drier.

Remark:

We have done the practical as well as possible. The sample of the dyed material seems to have correct shade and it shows good fastness especially wash fastness. So it is proved that maintaining proper temperature and time makes the experiment better.

Conclusion:

Now a days Reactive dye is used for dyeing cellulosic fibres which is mostly used in most of the dyeing industry. Cold brand reactive dye has reactive group of high reactivity. We come to know about the function of the ingredients of dyeing solution used for dyeing with cold reactive dye By this experiment we came to know that cold brand reactive dyes that are of the high reactivity because they take less temperature and less time for dyeing. This practical will help us in our study life as well as job life. Especial thanks to our teacher and his assistants for great co-operation.

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