Process for improving stain resistance and lightfastness of carpet yarn

Abstract

Disclosed is a method for dyeing solution dyed bulk continuous filament (BCF) fibers. The BCF fibers are twisted together to form a 2 or more ply strand prior to dyeing. After twisting the fibers together, the fiber is preferably spaced dyed to provide a multi-colored pattern along the length of the strand. Following the space dyeing step, the strand is heat set.

What is claimed is: 
     
         1 . A method for dyeing carpet fibers comprising the following steps, carried out in the following order:
 A. providing two or more solution dyed bulk continuous filament (BCF) fibers;   B. twisting the two or more BCF fibers to form a 2 or more ply strand;   C. space dyeing the twisted non-heat set strand; and   D. heat setting the twisted space dyed strand.   
     
     
         2 . The method of  claim 1  wherein the BCF fibers are formed using a cationic-based polymer. 
     
     
         3 . The method of  claim 2  wherein the BCF fibers are formed using cationic-based polyamide polymer. 
     
     
         4 . The method of  claim 1  wherein a pre-metalized dye is applied during the space dyeing step (i.e., Step C). 
     
     
         5 . The method of  claim 4  wherein the pre-metalized dye has a pH level of 2.5 to 3.0. 
     
     
         6 . The method of  claim 1  further comprising applying two or more different colors along the length of the strand during dyeing step (i.e., Step C). 
     
     
         7 . The method of  claim 1  wherein the space dyed strand is heat set in an atmospheric controlled climate to between 88° C. and 96° C. dew point temperature. 
     
     
         8 . The method of  claim 1  wherein the BCF fibers are formed from nylon type 6. 
     
     
         9 . The method of  claim 8  wherein the twisted space dyed strand is heat set using a temperature set point of 177° C. to 205° C. 
     
     
         10 . The method of  claim 1  wherein the BCF fibers are formed from nylon type 6.6. 
     
     
         11 . The method of  claim 10  wherein the twisted space dyed strand is heat set using a temperature set point of 193° C. to 215° C. 
     
     
         12 . The method of  claim 1  wherein a heat setting dwell time is between 45 and 65 seconds. 
     
     
         13 . The method of  claim 1  wherein the two or more BCF fibers are twisted using a direct cable machine, the strand is spaced dyed using a continuous yarn space dyeing apparatus, or the strand is heat set using a continuous heat setting apparatus. 
     
     
         14 . The method of  claim 1  further comprising the following steps, carried out in the following order after Step C and before Step D:
 E. washing the space dyed and heat set strand; and 
 F. steam setting the washed strand. 
 
     
     
         15 . The method of  claim 9  wherein the space dyed and heat set strand is washed at Step E in water having a temperature of at least 63° C. 
     
     
         16 . The method of  claim 10  wherein the washed strand is steam set at Step F in steam to a temperature of at least 98° C. over a water bath that is heated to at least 100° C. 
     
     
         17 . The method of  claim 10  wherein the washed strand is steam set at Step F for at least 4 minutes. 
     
     
         18 . A fabric comprising:
 a solution dyed strand formed from two or more bulk continuous filament (BCF) fibers twisted together; and   a dye applied to the solution dyed strand after the strand has been formed.   
     
     
         19 . The fabric of  claim 18  wherein the dye comprises two or more colors applied to the strand; 
     
     
         20 . The fabric of  claim 18  wherein the two or more colors repeat on the strand.