Desorption Kinetics of Hydrolyzed Reactive Dyes in Continuous Wash Ranges
Continuous wash ranges clear hydrolyzed reactive dye by maximizing thermal diffusion and maintaining steep counter-current concentration gradients across wash stages.
Chemical Wash off Dispersant
Functionality Definition
Auxiliary agents added to post dyeing baths prevent the redeposition of unfixed dye molecules onto the substrate. A chemical wash off dispersant maintains hydrolyzed reactive dyes or disperse dyes in a stable suspension within the liquor. This prevents staining of white grounds or adjacent fibers during the rinsing sequence.
The efficiency of the agent is typically evaluated through wash fastness tests.
Scouring Mechanism
Separation of loose pigments from the fiber surface occurs through the reduction of interfacial tension. This chemical wash off dispersant encapsulates the dye particles to stop them from aggregating or settling back onto the fabric. Effective dispersion is required when processing deep shades like navy or black where the concentration of unfixed dye is high.
The process ends once the liquor remains clear after a hot rinse. By forming a protective barrier around each dye molecule, the agent ensures that the rinse water carries the waste away to prevent migration.
Process Application
Application usually happens during the soaping stage of reactive dyeing on cotton or the reduction clear stage for polyester. Using a chemical wash off dispersant allows for a reduction in the number of rinse cycles. Lower water consumption results from higher dye removal efficiency per bath.
Performance Limit
Temperature sensitivity affects how well these compounds perform. A chemical wash off dispersant might lose its stabilizing properties if the bath temperature exceeds its cloud point. Excessive doses may interfere with certain softeners applied in subsequent steps.