Through-dyeing of cotton warp yarns with indigo

Abstract

The present invention relates to a process for through-dyeing of cotton warp yarns with indigo in an indigo dyeing range, which comprises dyeing in one pass at a dyeing temperature of 30 to 90° C. and an indigo concentration of 10-60 g/l.

1 . A process for through-dyeing of cotton warp yarns with indigo in an indigo dyeing range, which comprises dyeing in one pass at a dyeing temperature of 30 to 90° C. and an indigo concentration of 5-500 g/l.  
     
     
         2 . A process according to  claim 1  that utilizes indigo in the form of a solution of leuco indigo.  
     
     
         3 . A process according to  claim 2  wherein the leuco indigo has been produced from indigo by catalytic hydrogenation.  
     
     
         4 . A process according to  claim 1  wherein the process is further carried out in the presence of a wetting agent.  
     
     
         5 . A process according to  claim 4  wherein the wetting agent is used in amounts of 5 to 50 g/l.  
     
     
         6 . A textile article comprising cotton warp yarns dyed by the process according to  claim 1 .  
     
     
         7 . A process according to  claim 3 , wherein the process is further carried out in the presence of a wetting agent.  
     
     
         8 . A process according to  claim 7 , wherein the wetting agent is used in amounts of 10 to 25 g/l.  
     
     
         9 . A process according to  claim 1 , wherein said indigo concentration is 10-50 g/l.  
     
     
         10 . A process according to  claim 1 , wherein said indigo is a pre-reduced indigo.  
     
     
         11 . A process according to  claim 10 , wherein the pre-reduced indigo is produced from an indigo without the use of a reducing agent.  
     
     
         12 . A process according to  claim 2 , wherein the temperature is from 50 to 70° C.  
     
     
         13 . A process according to  claim 1 , wherein the dyeing is conducted at a pH from 10.5 to 13.5.  
     
     
         14 . A process according to  claim 8 , wherein the wetting agent is fatty alcohol ethoxylate, alkanesulfonate, sulfonsuccinate, alkyl phosphate, paraffin, hydrocarbon or mixtures thereof.  
     
     
         15 . A process according to  claim 8 , wherein the wetting agent is a salt of phosphoric esters.