Theory
Disperse dyes are non-ionic in nature and are insoluble in water. To hydrolyze it, high temperature is required. There are more crystalline regions in polyester. In acidic conditions, dyes are simply mechanically trapped in the fiber or fabric structure during dyeing. Thus, dispersed dyeing is done.
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Recipe
Recipe Calculation
Sample weight: 2 gm
Total liquor: 2 ✕ 20 = 40 ml
Dye = (Shade % ✕ Sample wt.) / (Stock solution%)
Disperse Red = (0.60 ✕ 2) / 1% = 1.2 ml
Disperse Blue = (0.40 ✕ 2) / 1% = 0.8 ml
Disperse Yellow = (0.80 ✕ 2) / 1% = 1.6 ml
Chemicals = (g/L ✕ Total liquor) / 1000
Dispersing agent = (1 ✕ 40) / 1000 = 0.04 gm
Acetic acid = (1 ✕ 40) / 1000 = 0.04 ml
Total = (1.2 + 0.8 + 1.6 + 0.04) = 3.64 ml
Freshwater = ( 200 - 3.64) = 36.36 ml
Functions of the Chemicals Required
Dispersing agent: It is used in polyester dyeing to distribute the dye molecules into the substrate.
Acetic acid: Its function is to control the pH and neutralize the solution of the dye bath.
Shade Attachment
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| Polyester Part Dyed Sample |
Dyeing Curve
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| Polyester Part Dyeing Curve |
Conclusion
The addition of dispersing agents increases the dye solubility and accelerates the dye diffusion into the swelled fiber structure. The high temperature helps in breaking the crystalline regions of the polyester fabric.