For cotton in India reactive dye maximum demand is there due to its brilliancy, reproducibility and wide range of shade possibility. Before dyeing in reactive dye fabric (ready for dyeing fabric) should be free from residual peroxide, alkali, size etc


Ready for dyeing cotton fabric in exhaust reactive dyeing required:


1)    Fabric absorbency should be less than 3 second by water drop check.

2)    Fabric should be free from residual peroxide or alkali

3)    Fabric Ph should be neutral .PH=6.5-7

4)    Fabric centre side variation checking by water and Ph indicator liquid solution. It should be uniformed throughout.


For lab to bulk correlation following point has to be considered for ready for dyeing fabric (RFD):


1)    Fabric Gsm (Gram secure meter) should be same for lab and bulk. For cabinet dyeing machine running lot pretreatment hank should be taken.

2)    Fabric absorbency should be less than 3 second.

3)    Fabric PH should be neutrals.

4)    Proper dye selection. Maximum try to take trichormy colour for shade matching.

5)    M; L ratio setting in machine and bulk.


For lab: a) for cabinet dyeing and winch machine:-1; 20

            b) For soft flow m/c=1; 10

            c) For Garment Dyeing m/c=1; 15


For Bulk dyeing (select those machine where following parameter is available).


a)    Water level indicator should be available for exact maintaining of material liquor ratio.

b)    Steam auto controller should be available for exact maintaining of dyeing temperature for evenness of shade.

Note: - for jigger dyeing take dyeing exert view for correlation maintaining because jigger dyeing material; liquor ratio will be 1; 1 to 1:2.


6)    Take same salt and soda ash for reactive exhaust dyeing. Quantity of salt and soda ash should for above mentioned machine.


Note: In Jigger dyeing lab salt and soda ash will be entirely different due to its low material; liquor ratio. In practical quantity of salt and soda ash will be entirely different as compared to lab recipe. Take expert view for correlation maintaining


7)    Lab recipe should be taken water bath as a heating medium for exact correlation maintaining because glycerin bath will not be correct for exhaust correlation maintaining.


8)    Soaping and neutralizing is always a variable factor for correlation maintaining in bulk.But for lab take soaping (for dark shade take 2 soaping for example-black ,dk maroon,dk turquoise blue shade, dk navy etc)at 90 degree celcius for 20 minute then hot wash(80 degree celcius ,holding time 10 minute) and dry.


In lab dyeing soaping mentioned bottom side:-


a) for light shade :( no soaping,) only hot wash.

b) For medium shade: only one soapinghot washescold wash.

c) For dark shade: two soapinghot washescold wash.


9)    Soft Water for dyeing should be taken for both Lab to bulk dyeing correlation maintaining. If water hardness is more use suitable sequestering agent available in market for bring down below 20 ppm. Water Ph should also check it should be neutral or slight acidic no problem.


10)   In lab dyeing no need for taking leveling agent /lubricating agent for exhaust dyeing .(But for bulk dyeing leveling agent /lubricating agent is must for soft flow dyeing machine to get entirely evenness in fabric. In cabinet dyeing machine huge quantity of water is used hence it is safer to used leveling /lubricating agent because water movement is also less and material also stationary.)

 

11)   For dark shade mixed alkali system was used for correlation maintaining in both lab to bulk dyeing.


12)  Soda ash holding time in bulk dyeing is a variable factor for exhaust reactive dyeing. But for lab dyeing taken salt holding time 30 minute and soda ash holding time 90 minute.


Note:-some variable factor has to be manipulated from dyeing expert view because lab dyeing sample we can get within 3 hour but bulk dyeing lot will take than 8 hour easily. In bulk each and every stage we can see sample but this is not possible in lab dyeing.


13)   Lab final sample no fixer was used for correlation maintaining.


For correlation maintaining:-


Dye used:-


1)    Corazol RFT Dye (colourtex):-Trichormy shade was selected in taken lab to bulk dyeing in for khakhi shade in soft flow machine (Single jersey cotton knitted quality)and cabinet dyeing machine(20 Cotton count). Variation was only 5% range in first lot.From first lot second lot was adjusted and now it is smoothly running This is excellent dye for different application area for example cabinet dyeing machine, soft flow dyeing machine, and winch machine. This dye is showing excellent result in Isothermal process. For more detail contact product management team (Cotton)


Carazol RFT series: - G.yellow RFT, Red RFT, Blue RFT, Deep red RFT, Navy RFT.


For continuous reproducibility in bulk dyeing following steps to be taken

a.    Standard cutting (As Upper limit for dyeing)

b.    Lab-dip approved sample recipe (Lower limit for dyeing).

c.    Lab recipe taken but matching done with standard cutting. For better reproducibility always matching to be done with standard cutting so that all lot will be in between upper and lower limit only.

2)    Cora fix GD series (Cora fix GD series): - It is excellent dye for dark shade in mixed alkali system. Nearly 2 ton dyeing done in cabinet dyeing machine in tripur (Tamil nadu) region Bulk sample is 15-20% depth more as compared to lab recipe for correlation maintaining. This Cora fixes GD series dye we have to select according to our use.


For continuous reproducibility in bulk dyeing following steps to be taken

a)    Standard cutting (As Upper limit for dyeing)

b)    Lab-dip approved sample recipe (Lower limit for dyeing).

c)    Lab recipe taken but matching done with standard cutting. For better reproducibility always matching to be done with standard cutting so that all lot will be in between upper and lower limit only.


Correlation is must for smoothly running of product in Exhaust reactive dye .Take dyeing expert view for correlation maintaining.


Note: This article has been written in good faith for helping technical people working in dyeing house. Situation from place to place will be not same for example-Panipat and Tripur. Entire selection of dye should be done from working experience expert only.


About the Author:


The author is the Product Manager (Reactive Dyes) in Colourtex. Ind. Ltd having 12 years production experience in cotton, polyester and its blend quality in India and overseas reputed company.


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