Dyeing of Woolen Yarns with Indigo Dyes

摘要

This research work involves the dyeing of woolen yarn with Indigo dye in package dyeing machine. Indigo, "Blue of Blue Denim" has been mostly applied using conventional method that use very high pH (11-12) to dye cotton [1]. Indigo is insoluble in water, to use it must be chemically reduced to a water soluble form (Yellowish -Green Color) which have affinity for the fiber after adsorption of reduced dye on the surface. It is oxidized back using chemical or air oxidation to convert it back to insoluble Blue form where dye remains in relative permanence [2]. Whereas, dyeing of wool is normally carried out in acidic conditions as chances of chemical attack on peptide & cysteine linkages is very high in alkaline condition causing deterioration of wool. In present work, dyeing of woolen yarns is carried out using Indigo at different depths in package dyeing machine. After dyeing, yarn breakage at loom was normal & both rubbing, and the washing fastness was found acceptable.