Last updated on July 16th, 2023 at 12:23 am
The machine was originally developed for solvent dyeing. The goods are placed in a rotating drum (D), which is rotated by a motor (M). The dye liquor is made up in the mixing tank (T). The drum is set in motion. The dye liquor is pumped via valve (V) and pump (P) and is sprayed onto the rotating load with the help of a sprayer (S) to give a pick-up of about 100% on wt of dry goods. The dye liquor contains:
The consumption of the foaming agent is not revealed, but sodium salt of lauryl sulphuric ester of an ethylene oxide condensate and nonylphenyl pentadecaglycol ether are quoted as possible foaming agents. In addition a foam stabilizer is required.
When the whole of the liquor has been discharged through the spray into the drum, the rotation is continued at cold for 15 minutes during which the foam bearing the dye is distributed uniformly throughout the charge. After 15 minutes, the temperature is raised to 1000C or at the temperature required for the particular dye-class, either with steam or hot air or both, and the machine is allowed to run at the temp. for 30-45 minutes during which fixation takes place.
The cycle may be programmed to carry out any desired sequence of operations such as dyeing, rinsing, finishing, centrifuging and drying. As the necessary amount of water is significantly lower is conventional process, the Sancowad technique resulted in substantial savings, in both water consumption and the energy required for heating.
The Sancowad foam-dyeing principle has been extended from batch wise to continuous dyeing systems and thus approaches to the saving of water and energy has been proved appropriate for the dyeing of pole fabrics and carpets.