|
Abstract:
|
Pad/batch dyeing is commonly used for the application of reactive dyes. In most
plants, the dye solution is padded onto dry fabric in a wet-on-dry process. In a wet-onwet
process, the dye solution is padded onto wet fabric directly after bleaching with no
intermediate drying step. Elimination of the drying step before dye application in the
wet-on-wet process lowers production costs. However, the wet-on-wet dyeing process
is susceptible to shade tailing, a decrease in the shade depth along the length of the
dyed fabric due to dyebath dilution.
The feasibility of wet-on-wet pad/batch dyeing was evaluated in this research. The
effect of the water content of the fabric entering the dye pad and the wet pickup in the
dye pad on dyebath dilution was examined. The possibility of preventing dyebath
dilution by altering the concentration of the dye solution used in dyebath reconstitution
was also investigated. Quality of the dyed goods was examined based upon fabric
lightfastness, washfastness, crockfastness, shade, and shade variability.
Several conclusions were drawn from this research. Shade tailing was prevented in
wet-on-wet pad/batch dyeing by modifying the concentration of the reconstitution
stream. Shade variation of the wet-on-wet dyed goods was no worse than that of the
wet-on-dry dyed goods. No difference was found between wet-on-wet and wet-on-dry
dyed goods with respect to lightfastness, washfastness, or crockfastness properties.
|