Process for Dyeing of Wool or Silk and Their Blends with Indigo

Abstract

A process for pretreatment of wool, silk or blends thereof rendering it receptive for the subsequent step of indigo dyeing. The pretreatment steps comprise in the step of cationization for imparting cationic charge and generating other dye combining sites.

1 - 8 . (canceled) 
   
   
       10 . A process for on line pretreatment of a substrate comprising:
 providing a substrate, wherein the substrate is selected from the group consisting of wool, silk, and blends thereof; and   pretreating the substrate, wherein pretreatment of the substrate comprises generating dye combining sites by treatment with at least caustic soda and for a period sufficient to generate said sites and without damaging said substrate.   
   
   
       11 . The process of  claim 10 , wherein the pretreatment step further includes the step of cationizing by passing the substrate through a pretreatment bath followed by aeration to provide a dwell period for the pretreated substrate. 
   
   
       12 . The process of  claim 11 , wherein the pretreatment step comprises treatment with caustic soda and a cationizing agent. 
   
   
       13 . The process of  claim 10 , wherein the step of pretreatment in the bath is carried out for 5 to 30 seconds and aeration for a period of 30 to 180 seconds. 
   
   
       14 . The process of  claim 11 , wherein the pretreatment bath comprises 3 to 80 gallons per liter of a cationizing compound and 3 to 25 gallons per liter of caustic soda. 
   
   
       15 . The process of  claim 11 , wherein the pretreatment bath comprises 3 to 25 gallons per liter of caustic soda. 
   
   
       16 . The process of  claim 10 , wherein pretreatment of the substrate is carried out at ambient temperature. 
   
   
       17 . The process of  claim 10 , wherein pretreatment of the substrate is carried out at 12-15° C.