Showing posts with label Dyeing. Show all posts
Showing posts with label Dyeing. Show all posts

Dyeing of cotton with mordant dye(alizarin dye)



The dyeing procedure of cotton with mordant dye(alizarin dye) is describe below:
            i.            At first cotton fabric is boiled in the solution of
Ø  1 part TR Oil &
Ø  10 part water for 12 hours.


          ii.            Then the fabric is dried at 40-60°C
        iii.            Treated again with al-acetate at 60°C for 2 hours.
        iv.            Then dry at 40-60°C.
          v.            Again treated with 2 parts Na-phosphate and 10 parts water at 40-40°C for 40 min.
        vi.            1-1.5% dye ( on the weight of fabric) is added in the solution with ca-acetate at room temperature for 30 minutes.
      vii.            Then fabric is hot rinsed (at 70°C) for 30 minutes.
    viii.            Finally the fabric is washed with soap solution and water and then dried.

Disperse dyeing effected by ph



Disperse dyeing effected by Temperature



In case of dyeing with disperse dye temperature plays an important role.for the swelling of fibre temperature about 100°C is required if high temperature dyeing method is applied. Again in case of carrier dyeing this swelling occurs at 85-90°C . Incase of thermosol dyeing method if temperature is kept more, fabric is kept for less time in thermosol unit. Because in higher temperature, less time is enough for thermofixation of dye. If it is kept for more time at high temperature dye submation and loss of fabric strength occur.

Dyeing mechanism of disperse dye



The dyeing of hydrophobic fabric with disperse dyes may be considered as a process of dye transfer from a liquire solvent ( water ) to a solid organic solvent(fibre).
Disperse dyes are added to water with a surface active agent to form an aqueous dispersion. The insolubility of disperse dyes enablethem to leave the dye liquor as they are more substantive to the application of that to the dye liquor increases the energy of dye molecules and accelerates the dyeing of textile fibres.
Heating the dye liquor swell the fibre to some extent and assists the dye to penetrate the fibre polymer system. Thus the dye nolecule takes its place in the amorphous regions of the fibre.withine the fibre polymer system, the dye molecules are held by hydrogen bonds and van der waals force.
The dyeing is considered to take place in the following simultaneous steps :-
1)      Diffusion of dye in solid phase, into water by breaking up into individual molecules. This diffusion depends on dispersibility and solubility of dyestuff and is aided by the presence of dispersing agent and increasing temperature.
2)      Adsorption of the dissolved dye from the solution onto the fibre surface. This dyestuff adsoeption by in the dye bath and that in the fibre.