Dye range, improved dye range processes, and yarns and fabrics produced therefrom

Abstract

The present invention relates to yarn dyeing, such as denim dyeing. A process provides a dyed yarn having reduced dye penetration and a white core at lower cost. The improved process for yarn dyeing is referred to herein as the CleanKore technology. The CleanKore technology improves one or more steps in dye ranges to achieve dyeing of the yarn while retaining a white core at the center of the yarn. When viewing a cross-section of a yarn, the peripheral portion is dyed while the center remains white (not dyed). The CleanKore technology modifies the scouring stage (or phase), the scour rinsing stage, the dyeing stage, and/or the dye rinsing phase of existing dye ranges. The modifications may be applied individually or any combinations thereof to the existing dye range.

1 . A method for dying yarns, comprising the steps of
 a. providing a dye range comprising a scouring stage, a scour rinsing stage, a dyeing stage, an oxidation stage, and a dye rinsing stage; and   b. modifying the dye range by three or more of the following steps to provide a modified dye range:
 i. reducing an immersion time of the single scouring vat in a range of about 4 total seconds to about 20 total seconds, 
 ii. maintaining a temperature in the single scouring vat at approximately equal to a temperature of the highest tap water temperature for the location of the dye range, 
 iii. maintaining a caustic concentration of about 0.5 to about 40 g/L in the scouring stage, 
 iv. maintaining a pH range of about 11 to about 12.2 in the scouring stage, 
 v. reducing a wetting agent in the scouring state to about 0.7 to about 4 g/L, 
 vi. reducing the scour rinsing stage to a single scour rinsing vat; 
 vii. reducing an immersion time in the scour rinsing vat to a range of about 4 total seconds to about 20 total seconds, 
 viii. optimizing water flow in the dye rinsing stage(s) to maintain a pH range of about 7 to 11 in the dye rinsing stage, 
 ix. eliminating the scouring stage and/or the scour rinsing stage, 
 x. reducing dwell time of the yarns, 
 xi. maintaining a temperature of dyeing stage within 5° C. of the highest tap water temperature for the location of the dye range, 
 xii. adjusting an immersion time of the yarn in the dyeing stage to about 7 to about 18 seconds, 
 xiii. removing or reducing any wetting agents in the dyeing stage, 
 xiv. maintaining a dye immersion time to oxidation time ratio of about 1:6 to about 1:18, and 
 xv. providing a first dye rinsing vat and a second dye rising vat in the dye rinsing stage, the first dye rinsing vat has an immersion time of about 4 to about 12 seconds, and the second dye rising vat has an immersion time of about 7 to about 22 seconds. 
   
     
     
         2 . The method of  claim 1 , wherein steps i, vii, x, xii, xiv, and xiv are accomplished by changing the threading path of the yarns through rollers in the dye range and/or removing some of the rollers. 
     
     
         3 . The method of  claim 1 , wherein step i has an immersion time of about 5 seconds to about 13 seconds. 
     
     
         4 . The method of  claim 1 , wherein the mV of dying stage is maintained in a range between −675 mV and −750 mV. 
     
     
         5 . The method of  claim 1 , wherein step x is accomplished by threading the yarns to provide the shortest path between the scouring step and the scour rinsing step, and between the scour rinsing step and the dyeing step. 
     
     
         6 . The method of  claim 1 , wherein the caustic concentration in the scouring stage is maintained in a range of about 0.5 g/L to 8 g/L. 
     
     
         7 . The method of  claim 1 , wherein the dyeing stage uses indigo dye or sulphur dye. 
     
     
         8 . The method of  claim 7 , wherein the sulphur dye is heated to a temperature range of 70° C. to 80° C. 
     
     
         9 - 13 . (canceled) 
     
     
         14 . A method for modifying a dye range, said dye range includes a sulphur dye and scouring combination stage, a sulphur scour combination rinsing stage, indigo dyeing stage, oxidation stage, and an indigo dye rinsing stage, the method comprises the following steps:
 i. reduce an immersion time of the sulphur scour combination tank to range of about 4 seconds to about 15 seconds   ii. reducing a wetting agent in the sulphur scour combination stage in a range of about 0.7 g/L to about 4 g/L,   iii. adjusting an immersion time of the yarn in the indigo dyeing immersion stage to range of about 7 to about 18 seconds,   iv. removing wetting agents in the indigo dyeing stage,   v. optimizing water flow in the indigo dye rinsing stage to maintain a pH range of about 7 to about 11 in the dye rinsing stage.   
     
     
         15 . The method of  claim 14 , wherein the water flow to the sulphur scour combination rinsing stage is maintain a pH in the range of about 7 to about 11. 
     
     
         16 . The method in  claim 14 , wherein the time ratio of dye immersion and air oxidation is within a range from 1:7 to 1:15 
     
     
         17 . The method of  claim 14 , where in the temperature of the sulphur dye and scouring combination stage is maintained between 70° C. and 80° C. 
     
     
         18 . The method of  claim 14 , where in the sulphur scour combination rinsing stage is not additionally heated beyond the tap water temperature. 
     
     
         19 . The method of  claim 14 , wherein yarns are threaded in the shortest path between the sulphur dye and scouring combination stage nip roller and the sulphur scour combination rinsing stage. 
     
     
         20 . The method of  claim 14 , wherein the water flow is such that the pH of the indigo dye rinsing stage is maintain in a range between 9.5 and 10.2. 
     
     
         21 . The method of  claim 14 , wherein the solution used in the indigo dyeing stage is heated within about 5° C. of the highest tap water temperature experienced at a respective dye range in a typical year. 
     
     
         22 . A method of dyeing a yarn having a cleaned periphery and an uncleaned center core, comprising the steps of:
 a. providing a cotton yarn having impurities distributed throughout the yarn;   b. passing the yarn through a scour bath so that only some of the impurities are removed from the yarn, the remaining impurities being situated within the central area of the yarn;   c. passing the scoured yarn through at least one dye bath so that the dye infiltrates the scoured portion of the yarn;   d. fixing the dye to the yarn.   
     
     
         23 . The method of  claim 22 , including the steps of passing the yarn through a plurality of dye baths and/or through a plurality of rinse baths and/or through a plurality of oxidizing stages. 
     
     
         24 . The method of  claim 22 , including the step of passing the yarns through at least one scour bath, the at least one scour bath including dye. 
     
     
         25 . The method of  claim 22 , including the steps of:
 a. providing a dye bath that contains indigo dye stuffs;   b. dyeing the yarn with the indigo dye; and   c. oxidizing the dyed yarn after it exits the dye bath.   
     
     
         26 - 30 . (canceled)