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Textile Engineering / Mechanism of disperse dyeing
« on: January 18, 2017, 10:37:23 AM »
The dyeing of hydrophobic fibers like polyester fibers with disperse dyes may be considered as a process of dye transfer from liquid solvent (water) to a solid organic solvent (fiber).
Disperse dyes are added to water with a surface active agent to form an aqueous dispersion. The insolubility of disperse dyes enables them to leave the dye liquor as they are more substantive to the organic fiber than to the inorganic dye liquor. The application of heat to the dye liquor increases the energy of dye molecules and accelerates the dyeing of textile fibers.
Heating of dye liquor swells the fiber to some extent and assists the dye to penetrate the fiber polymer system. Thus the dye molecule takes its place in the amorphous regions of the fiber. Once taking place within the fiber polymer system, the dye molecules are held by hydrogen bonds and Van Dar Waals’ force.
Dyeing of hydrophobic fibers like polyester fibers with disperse dyes may be considered as a process of dye transfer from a liquid (water) to a solid organic solvent (fiber) and the dyeing takes place in the following stages—
a) Dispersion of the dye into water by breaking up into molecules (Dissolution in water): The dissolution depends on the disposability and solubility of the dyestuff further aided by the presence of dispersing agents and Raise the temp.
b) Adsorption of the dissolved dye form the solution on to the fiber surface: The dye staff adsorption by the fiber surface is influenced by the solubility of the dye in the dye bath and that in the fiber.
c) Diffusion of the dye molecules from the fiber surface into the interior of the fiber substance towards the center: The diffusion rate governs the overall rate of dyeing. When equilibrium state is reached, the following subsidiary equilibrium are established-
i) Dye dispersion in the dye bath dye dissolved in the dye bath
ii) Dye dispersion in the dye bath dye absorbed on the fiber surface.
iii) Dye absorbed on the fiber surface dye diffused in the fibro
iv) dye diffused in the fiber dye diffused fiber to dye bath.
Disperse dyes are added to water with a surface active agent to form an aqueous dispersion. The insolubility of disperse dyes enables them to leave the dye liquor as they are more substantive to the organic fiber than to the inorganic dye liquor. The application of heat to the dye liquor increases the energy of dye molecules and accelerates the dyeing of textile fibers.
Heating of dye liquor swells the fiber to some extent and assists the dye to penetrate the fiber polymer system. Thus the dye molecule takes its place in the amorphous regions of the fiber. Once taking place within the fiber polymer system, the dye molecules are held by hydrogen bonds and Van Dar Waals’ force.
Dyeing of hydrophobic fibers like polyester fibers with disperse dyes may be considered as a process of dye transfer from a liquid (water) to a solid organic solvent (fiber) and the dyeing takes place in the following stages—
a) Dispersion of the dye into water by breaking up into molecules (Dissolution in water): The dissolution depends on the disposability and solubility of the dyestuff further aided by the presence of dispersing agents and Raise the temp.
b) Adsorption of the dissolved dye form the solution on to the fiber surface: The dye staff adsorption by the fiber surface is influenced by the solubility of the dye in the dye bath and that in the fiber.
c) Diffusion of the dye molecules from the fiber surface into the interior of the fiber substance towards the center: The diffusion rate governs the overall rate of dyeing. When equilibrium state is reached, the following subsidiary equilibrium are established-
i) Dye dispersion in the dye bath dye dissolved in the dye bath
ii) Dye dispersion in the dye bath dye absorbed on the fiber surface.
iii) Dye absorbed on the fiber surface dye diffused in the fibro
iv) dye diffused in the fiber dye diffused fiber to dye bath.