Scouring Process for Ring Dyed Denim Fabric and Material Produced Thereof

Abstract

Ring dyeing of yarn with indigo dye to produce an improved white core, An outer surface of the yarn is scoured prior to applying the indigo dye, and then applying the indigo dye is applied. Scouring parameters of the dyeing are used to limit a penetration of the indigo into the white core, so that the white core has mostly sections of white yarn, and the yarn has indigo dye on the outer surface, said parameters comprising limiting scouring parameters to at least 10% below current parameters used to scour the yarn.

What is claimed is: 
     
         1 . A method comprising
 dyeing yarn with indigo dye that has an improved white core,   said dyeing comprising scouring an outer surface of the yarn prior to applying the indigo dye, and then applying the indigo dye; and   using scouring parameters of the dyeing to limit a penetration of the indigo into the white core, so the white core has mostly sections of white yarn, and the yarn has indigo dye on the outer surface, said parameters comprising limiting scouring parameters to at least 10% below current parameters used to scour the yarn.   
     
     
         2 . The method as in  claim 1 , wherein the parameters, include limiting a temperature of the dyeing. 
     
     
         3 . The method as in  claim 2 , wherein the temperature is limited to 30-45° C. 
     
     
         4 . The method as in  claim 2 , wherein the temperature is a highest room temperature experienced year round. 
     
     
         5 . The method as in  claim 1 , wherein the parameters include reducing a concentration of the chemicals used within the scouring stage, including reducing a concentration of wetting agents, which act as a lubricant in the scour vat to about 2 g/L. 
     
     
         6 . The method as in  claim 1 , wherein the parameters include a caustic concentration of 8 g/L or less of 50% concentration. 
     
     
         7 . The method as in  claim 1 , wherein the parameters include reducing immersion time in a scour vat in which the yarn is initially cleaned. 
     
     
         8 . The method as in  claim 7 , wherein the immersion time is reduced by modifying rollers used to immerse the yarn in the scour vat. 
     
     
         9 . The method as in  claim 8 , wherein the modifying includes at least one of skipping rollers, changing a path of rollers, changing a diameter of the rollers, removing rollers, or reducing a collective volume of chemicals relative to a size of the vat. 
     
     
         10 . The method as in  claim 1 , wherein the scouring parameters include reducing a dwell time between a scour vat and a rinse tank. 
     
     
         11 . The method as in  claim 10 , wherein the dwell time is reduced by threading the yarns to travel directly to the rinse tank from the scour tank. 
     
     
         12 . The method as in  claim 1 , wherein the scouring parameters include using a scour tank to scour the yarn, and using a rinse tank with a desired proximity to the scour tank to more accurately control a scour potential by limiting a dwell time. 
     
     
         13 . The method as in  claim 1 , wherein the scouring parameters include increasing a nip pressure on rollers where the yarn is pinched between the nip rollers to creates a wringing and squeezing action, reducing the volume of chemistry that would otherwise remain on the yarn during the dwell stages and pollute the subsequent tanks or vats. 
     
     
         14 . The method as in  claim 13 , wherein the nip pressures are increased to a range of about 5.0 to 7.0 bar throughout scour, dye, and rinse stages of processing the yarn. 
     
     
         15 . The method as in  claim 1 , wherein the scouring parameters include increasing a nip pressure on rollers used to convey the yarn to around 5.8 bar, scouring with 100% caustic flake at about 4 g/l, and using a scour wetter of about 2 g/L. 
     
     
         16 . The method as in  claim 1 , wherein the scouring parameters include increasing a nip pressure on rollers to around 4.8 bar, scouring in a 100% flake caustic at 4 g/l, and using a scour wetter of 2 g/L. 
     
     
         17 . The method as in  claim 1 , wherein the scouring parameters limiting the scour to reduce an area that the dye can effectively penetrate as a function of yarn diameter, so that smaller diameter yarns are exposed to a reduced scour potential. 
     
     
         18 . A method comprising
 dyeing yarn using an indigo dye,   said dyeing comprising scouring an outer surface of the yarn prior to applying the indigo dye, and then applying the indigo dye; and   using scouring parameters of the dyeing, including at least multiple of:   temperature of the dyeing,   reducing a concentration of wetting agents,   reducing immersion time in a scour vat in which the yarn is initially cleaned, reducing a dwell time between the scour vat and a rinse tank,   increasing a nip pressure to limit a penetration of the indigo into the white core, so the white core has mostly sections of white yarn, and the yarn has indigo dye on the outer surface, said parameters comprising limiting scouring parameters to reduce an amount of the yarn that allows the dye to penetrate.   
     
     
         19 . The method of  claim 18  where dye penetration and fastness is more uniform then that for standard dyed yarns. 
     
     
         20 . The method of  claim 19  where the uniformity means that the dye experiences both similar penetration and oxidized fixation in a shape that more closely follows the outer surface outline of a given warp yarn 
     
     
         21 . The method of  claim 1  where sulphur dyes may be used before or after the indigo dyes 
     
     
         22 . The method of  claim 1  where the brightness achieved when using potassium permanganate spray (PP spray) on a garment can be replicated with CleanKore and laser treatment thus eliminating the need for PP spray. 
     
     
         23 . A method to achieve improved white cores in dyed yarn comprising
 dyeing yarn using an indigo dye,   said dyeing comprising scouring an outer surface of the yarn prior to applying the indigo dye, and then applying the indigo dye; and   using scouring parameters of the dyeing, including at least multiple of:   reduce the scouring temperature to room temperature or 30-45° C.   reducing a concentration of wetting agents to 1-4 g/L caustic,   reducing caustic concentration to 4-60 g/L of 50% concentration,   reducing immersion time in a scour vat in which the yarn is initially cleaned by 10-60% from normal practices,   reducing a dwell time between the scour vat and a rinse tank of at least 10% from normal practices,   reducing the number of rinse vats to less than 3 and   increasing a nip pressure on rollers used to convey the yarn to 5.0-7.0 bar.