HOW FOAM DYEING PROCESS TAKES PLACE…
The foam dyeing technology consist of three sequential chambers: the purge chamber, application chamber and kinetic chamber so as to ensure anaerobic environment for dyeing.
Purge Chamber removes oxygen from the yarns before entering into the application chamber. This eliminates the use of sulphur reducing compounds which are primarily used during the conventional wet dyeing.
Application Chamber controls the delivery of foambased dye liquor to deliver the dye liquid from the collapsed foam. It enables the control of dye uptake and penetration.
Kinetic Chamber is mainly responsible for modulating dye absorption so as to minimise the amount of detrimental surface indigo as well as wasted indigo. It also enhances the darkness of blue colour and improves the colour-fastness property.
For reliable foam dyeing process along with the chambers, there should be a yarn handling system. Since yarns do not behave as structured fabric, thus in this case, foam dyeing technique is highly effective along with the reactive and other nonoxidising dyestuff. Consistent quality requires consistent control of both yarns as well as foam.
The yarn handling system is responsible for delivering yarns from a small beam through the dyeing system and rewinding the dyed yarns onto another beam. It provides computerised control of yarn tensions from the beginning to end. Also a yarn creel with computerised control of yarn tensions is attached to the system just to ensure the yarn packages are consistently fed into the yarn handling system.
The system also contains a foam generator for fabrication. The generator delivers metered foam directly on the sheets when it passes over a sequence of rollers. It is connected with the yarn handling system so that constant yarn tension is maintained throughout. It also enables real-time adjustment of the foam blow ratios as well as wet pick-up levels.
The oxidation and the drying rack which is present inbetween the kinetic chamber and the yarn take-up beam is mainly responsible for the oxidation process of the dyed yarns. Yarns need time to oxidise before drying as moisture is required for oxidation to take place. The process of oxidation happens quite rapidly and the design of the rack is adequate enough even when running at high speed.
Royo stated that it is a system that is entirely free of water, that is, a dry dyeing process in which indigo is applied using foam. This breathtaking technology not only saves water but also cuts down on the consumption of chemicals by 90 per cent. What is more, energy consumption is also reduced tremendously. He added that the future of indigo dyeing lies in sustainable production.