Abstract


Cabinetdyeing machine is popular for reactive dyeing of cotton hanks. The maindrawback of this technique is high material to liquor ratio (1:15).Due to highmaterial liquor ratio, it requires high amount of salt to transfer the dye fromliquor to the yarn. The current study aims at reduction of material to liquorratio to as low as 1:1 and eliminate salt during dyeing of cotton hanks usingultra low liquor dyeing machine developed by NITRA. A comparison is also madebetween conventional and newly developed technique. Dyed hanks were alsoevaluated for colour fastness properties. The dyed samples were found to havehigh fixation percentage and excellent color fastness properties. Thetechnology thus developed will not only conserve the resources, but also makethe process eco friendly fulfilling the needs of small and medium scale dyeingunits.


Introduction


Cottonyarns are traditionally dyed either in the form of packages or hanks by batchprocess using exhaust method. The biggest drawback of hank dyeing is generationof total dissolved solids (TDS) due to addition of huge amount of salt at rateof 30-80gpl. For this reason the Australian dyeing company (ADC) adoptedcleaner production method for yarn dyeing i.e. cold-pad-batch dyeing ofreactive dyes (CPB)1. The process has been proven to be moreecologically sound, more cost efficient, and produces better quality productthan conventional method. ADC installed the latest developed continuous yarndyeing equipment for fine counts. This dyeing system works at 1: 0.3 to 0.45 MLR.100% cotton yarns were dyed without addition of salt using cold pad batchmethod. Using the cold pad batch dyeing process for yarn and fabric, ADC wasable to achieve 45% reduction in water consumption, 48% reduction in steam comparison,33% saving in electricity and 100% reduction in salt consumption, totallyremoving salt from the effluent 2. On similar line in the presentstudy a new technique based on semi-continuous principle is developed, whichnot only eliminates use of salt but also reduces material to liquor ratio from1:15 (Cabinet dyeing) to 1:1. The present study was carried out in two parts,improvisation of commercial recipe making suitable for the semi-continuousprocess and consumption of ultra low liquor dyeing processes with that ofconventional exhaust dyeing of cotton hank yarn.


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The authors areassociated with Northern India Textile Research Association, Ghaziabad and Ms.Mona Suri is from the Department of FAS, Lady Irwin College, Delhi University.