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. Hot brand reactive dyes have low reactivity.

Reaction:

Combination color :

Red = 1.25%
Blue = 0.05%
Yellow = 0.5%

Recipe :

Dye : Blue (CIBA CRON BLUE FN-R) = 0.05%
Dye : Red (CIBA CRON RED FN-R)= 1.25%
Dye : Yellow (CIBA CRON YELLOW FN-R) = 0.5%
Sequestering agent =0.5 g/L
Wetting agent = 1 g/L
Soda = 80g/L
Salt = 20 g/L
M: L = 1:30
P^H= 6-7 for exhaustion = 11 ± 0.5 for fixation
Time = 30 ¢ – 40 ¢ for exhaustion = 45 ¢ – 60 ¢ for fixation.
Temperature = 30⁰ -40⁰C for exhaustion = 50⁰-60⁰C for fixation.

Calculation :

Material weight= 5 gm.
Total liquor = 150 cc.
Required Dye = ( Material Weight x Shade % ) / Stock Solution %
Red = ( 5 x 1.25 ) / 1 % = 6.25 CC
Yellow = ( 5 x 0.5 ) / 1 % = 2.5 CC
Blue = ( 5 x 0.05 ) / 1 % = 0.25 CC
Formula for others chemicals = ( Recipe Amount x Total Liquor ) / ( 1000 x Stock Solution % )
Amount of Wetting Agent = ( 1 x 150 ) / ( 1000 x 1% ) = 15 C.C.
Amount of Squestering Agent = ( 0.5 x 150 ) / ( 1000 x 1% ) = 7.5 C.C.
Amount of Soda = ( 20 x 150 ) / ( 1000 x 20% ) = 15 C.C.
Amount of Salt = ( 80 x 150 ) / ( 1000 x 20% ) = 60 C.C.
Water Required = { 150 – ( 6.25 + 2.5 + 0.25 + 15 + 7.5 + 15 + 60 ) } = 43.5 CC

Dyeing curve :

Procedure :

According to dyeing curve at first auxiliaries and water are added in the dye bath.
Then it is kept for 5 minutes at room temperature.
Then material, dye is added respectively and starts heating for 5 minutes at 30⁰-40⁰C.
Then salt is added.
After adding salt dye bath is kept for 20-30 minute without adding or giving any temperature.
Then alkali is added in the dye bath. After adding alkali the dye bath is heated for 45-60 minute at 80-90⁰C.

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:

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 does the experiment.

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