Indigo and ring dyeing process using sulfur dye as barrier, and material produced thereby

Abstract

A method of ring dyeing a yarn includes the steps of providing a cellulosic yarn chosen from the group consisting of open-end yarns and ring yarns. The yarn is immersed in only one sulfur dye box, the sulfur dye box having a sulfur concentration of 1 to 50 grams/liter. The yarn is skyed for less than 30 seconds after removal from the sulfur dye box. The yarn is rinsed in water after skying. The yarn is dyed in an indigo dye bath, with the indigo dye bath maintained at a pH of 10.8 and 12.8. The yarn is skyed after removal from the indigo dye box.

1 . A method of ring dyeing a yarn, comprising the steps of:
 providing a cellulosic yarn chosen from the group consisting of open-end yarns and ring yarns;   immersing the yarn in only one sulfur dye box, the sulfur dye box having a sulfur concentration of 1 to 50 grams/liter;   skying the yarn for less than 30 seconds after removal from the sulfur dye box;   rinsing the yarn water after skying;   dyeing the yarn in an indigo dye bath, the indigo dye bath maintained at a pH between 10.8 and 12.8; and   skying the yarn after removal from the indigo dye box.   
     
     
         2 . The method as defined in  claim 1 , including maintaining the sulfur dye bath at a temperature of 50 to 100° C. 
     
     
         3 . The method as defined in  claim 2 , including maintaining the sulfur dye bath at a temperature of 65 to 85° C. 
     
     
         4 . The method as defined in  claim 1 , including the step of providing a continuous water flow at room temperature for rinsing the yarn. 
     
     
         5 . The method as defined in  claim 1 , including the step of skying the yarn after removal from the sulfur dye bath for less than 18 seconds. 
     
     
         6 . The method as defined in  claim 1 , including the step of maintaining the indigo dye bath at a pH between 11.4 to 11.6. 
     
     
         7 . The method as defined in  claim 1 , including the step of maintaining the indigo dye bath at −680 to −780 MV. 
     
     
         8 . The method as defined in  claim 7 , including the step of maintaining the indigo dye bath at −715 to −725 MV. 
     
     
         9 . The method as defined in  claim 1 , including the step of skying the yarn for 45 to 120 seconds after removal from the indigo dye bath. 
     
     
         10 . The method as defined in  claim 1 , including the step of maintaining the sulfur dye at a pH of 10.0 and 13.7. 
     
     
         11 . The method as defined in  claim 1 , including the step of maintaining the pH in the sulfur rinse bath under 11.4. 
     
     
         12 . The method as defined  claim 1 , including the step of immersing the yarn in the sulfur dye bath for 6 to 14 seconds. 
     
     
         13 . The method as defined in  claim 1 , including the step of skying the yarn for between 30 to 140 seconds after removal from the indigo dye bath. 
     
     
         14 . A method of ring dyeing a yarn, comprising the steps of:
 providing a cellulosic yarn chosen from the group consisting of open-end yarns and ring yarns;   immersing the yarn in only one sulfur dye bath for between 6 to 14 seconds, the sulfur dye bath having a sulfur concentration of 1 to 50 grams/liter;   skying the yarn for less than 30 seconds after removal from the sulfur dye bath;   rinsing the yarn in water after skying;   thereafter dyeing the yarn in an indigo dye solution for between 6 to 14 seconds, the dye solution maintained at a pH of 10.8 to 12.8; and   thereafter skying the yarn for 30 to 140 seconds.   
     
     
         15 . The method as defined in  claim 14 , wherein the dye solution is one of indigo, sulfur black, and shades of sulfur. 
     
     
         16 . The method as defined in  claim 14 , including the step of maintaining the sulfur dye at a temperature of 50 to 100° C. 
     
     
         17 . The method as defined in  claim 14 , including the step of skying the yarn after removal from the sulfur dye bath for less than 18 seconds. 
     
     
         18 . The method as defined in  claim 14 , including the step of rinsing the yarn with continuous water flow at room temperature. 
     
     
         19 . The method as defined in  claim 14 , wherein skying the yarn lasts for between 45 to 120 seconds after removal from the indigo dye bath. 
     
     
         20 . The method as defined in  claim 14 , including the step of maintaining the sulfur dye at a pH of 10.0 to 13.7. 
     
     
         21 . A method of dyeing yarn, comprising the steps of:
 Providing a cellulosic yarn;   Immersing the yarn in a caustic solution;   Rinsing the yarn in water to remove excess caustic;   Immersing the yarn is sulfur dyes for a limited immersion time;   Skying the yarn after dyeing for a limited time to minimize air oxidation of the dye;   Rinsing the yarn in water to oxidize the sulfur dyes and remove unreacted dyes from the yarn;   Immersing the yarn in indigo for a limited immersion time; and   Skying the yarn for a period sufficient to oxidize the indigo dye.   
     
     
         22 . The method of  claim 14 , including the step of applying the sulfur dye with a MV between −680 and −800. 
     
     
         23 . The method of  claim 22 , including the step of maintaining the MV between −715 and −725 MV. 
     
     
         24 . A garment manufactured from a fabric having yarns dyed as defined in  claim 1 .