Fabric Response Characteristics for Laser Finishing

Abstract

A fabric has enhanced response characteristics for laser finishing. The fabric can be denim for denim apparel such as jeans. Software and lasers are used to finish apparel made of the fabric to produce a desired wear or distressing pattern or other design. The fabric allows for relatively fast color change in response to the laser, color changes in hue from indigo blue to white, many grayscale levels, and maintains strength and stretch properties. A method used to make the fabric includes spinning, dyeing, and weaving yarns in such a way to obtain the desired enhanced response characteristics for laser finishing.

The invention claimed is: 
     
         1 . A method comprising:
 processing a cotton rope comprising cotton yarns using an indigo dye so a cotton yarn will have a cross section comprising an outer ring and an inner core, wherein a thickness of the outer ring is from about 7.5 percent to about 12.5 percent of a total thickness of the yarn, and the outer ring is indigo colored due to being penetrated through by the indigo dye while the inner core is white or off-white colored due to not being penetrated to by the indigo dye; and   weaving the dyed cotton yarn into a denim fabric, wherein the warp yarns comprise dyed cotton and the weft yarns comprise undyed cotton, and the denim fabric is to be finished by exposing the dyed cotton yarn to a laser, and   when exposed to the laser, the laser creates a finishing pattern on a surface of the garment based on a laser input file provided to the laser, and the laser input file comprises a plurality of laser exposure values, each for a different laser pixel location,   for each laser exposure value, the laser removes a depth of material from the surface of the denim material that corresponds to the laser exposure value, and   for lighter pixel locations of the finishing pattern, a greater depth of the indigo ring-dyed cotton yarn is removed, revealing a greater width of an inner core of the dyed yarn, as compared to darker pixel locations of the finishing pattern, where a lesser depth of the indigo ring-dyed cotton yarn is removed, revealing a lesser width of an inner core of the dyed yarn.   
     
     
         2 . The method of  claim 1  wherein the processing a cotton rope comprises:
 immersing the cotton yarn into at least one indigo dye solution having a pH in a range from about 10.7 to about 11.8. 
 
     
     
         3 . The method of  claim 1  wherein the processing a cotton rope comprises:
 immersing the cotton yarn into at least one indigo dye solution having a pH of about 11.8 or less. 
 
     
     
         4 . The method of  claim 1  wherein the processing a cotton rope comprises:
 mercerizing an undyed cotton yarn in an alkaline solution before an initial immersion of the undyed yarn into an indigo dye solution. 
 
     
     
         5 . The method of  claim 1  wherein the processing a cotton rope comprises:
 immersing the cotton yarn into at least one indigo dye solution having a pH in a range from about 10.7 to about 12.0; and 
 maintaining a temperature of the indigo dye solution at about 75 degrees Celsius or less while the cotton yarn is being immersed. 
 
     
     
         6 . The method of  claim 1  wherein the processing a cotton rope comprises:
 immersing the cotton yarn into at least one indigo dye solution having a pH in a range from about 10.7 to about 12.0; and 
 maintaining a temperature of the indigo dye solution at about 88 degrees Celsius or less while the cotton yarn is being immersed. 
 
     
     
         7 . The method of  claim 1  wherein the processing a cotton rope comprises:
 not immersing the cotton yarn into a solution comprising sulfur dyestuff before an initial immersion of the cotton yarn into an indigo dye solution. 
 
     
     
         8 . The method of  claim 1  wherein the laser finishing can produce at least 32 different grayscale levels on the denim fabric. 
     
     
         9 . The method of  claim 1  wherein the laser finishing can produce at least 64 different grayscale levels on the denim fabric. 
     
     
         10 . The method of  claim 1  wherein the laser finishing can produce at least 128 different grayscale levels on the denim fabric. 
     
     
         11 . The method of  claim 1  wherein the cotton yarn comprises a yarn twist of about 4.6 or more twists per inch. 
     
     
         12 . The method of  claim 1  the processing a cotton rope comprises:
 mercerizing an undyed cotton yarn in an alkaline solution before an initial immersion of the undyed yarn into an indigo dye solution; and 
 immersing the mercerized cotton yarn into five or fewer separate dips of indigo dye solution having a pH of about 11.8 or less. 
 
     
     
         13 . A method comprising:
 providing a garment made from fabric panels of a denim material, wherein the fabric panels are sewn together using thread,   the denim material will be finished by using a laser to remove selected amounts of material from a surface of the denim material at selected locations of the garment,   the denim material comprises an indigo ring-dyed cotton yarn having cross section comprising an outer ring and an inner core, a cross-sectional profile of the outer ring relative to the inner core is compatible with the laser to obtain at least 32 different grayscale levels, and the cross-sectional profile comprises a thickness of the outer ring that is from about 7.5 percent to about 12.5 percent of a total thickness of the yarn,   the outer ring is indigo colored due to being penetrated through by an indigo dye while the inner core is white or off-white colored due to not being penetrated to by the indigo dye, and the indigo ring-dyed cotton yarn with laser-compatible cross-sectional profile is obtained by   mercerizing an undyed yarn in an alkaline solution to obtain an mercerized undyed yarn, and   immersing the mercerized undyed yarn into at least one indigo dye solution having a pH in a range from about 10.7 to about 12.0; and   exposing the garment to a laser to create a finishing pattern on a surface of the garment based on a laser input file provided to the laser,   wherein the laser input file comprises a plurality of laser exposure values, each for a different laser pixel location, and   for each laser exposure value, causing the laser to remove a depth of material from the surface of the garment that corresponds to the laser exposure value,   whereby for lighter pixel locations of the finishing pattern, a greater depth of the indigo ring-dyed cotton yarn is removed as compared to darker pixel locations of the finishing pattern, where a lesser depth of the indigo ring-dyed cotton yarn is removed.   
     
     
         14 . The method of  claim 13  wherein based on a value stored in laser input file, the laser removes a selected depth of material starting from the outer surface of the yarn, and as a result, a vertical segment of the inner core is revealed by the laser between outer core segments that is in a range from 0 to about 85 percent of the total thickness of the yarn, thereby producing at least 64 different grayscale levels on the denim material. 
     
     
         15 . The method of  claim 13  wherein undyed yarn comprises a yarn twist from about 4.5 to about 4.8 twists per inch. 
     
     
         16 . The method of  claim 13  wherein the indigo ring-dyed cotton yarn with laser-compatible cross-sectional profile is obtained further by
 maintaining a temperature of the indigo dye solution at about 88 degrees Celsius or less while the mercerized undyed yarn is being immersed. 
 
     
     
         17 . The method of  claim 13  wherein the indigo ring-dyed cotton yarn with laser-compatible cross-sectional profile is obtained further by
 maintaining a temperature of the indigo dye solution at about 88 degrees Celsius or less while the mercerized undyed yarn is being immersed. 
 
     
     
         18 . The method of  claim 13  wherein the indigo ring-dyed cotton yarn with laser-compatible cross-sectional profile is obtained further by
 maintaining a temperature of the indigo dye solution at about 75 degrees Celsius or less while the mercerized undyed yarn is being immersed. 
 
     
     
         19 . The method of  claim 13  wherein the indigo ring-dyed cotton yarn with laser-compatible cross-sectional profile is obtained further by
 not immersing the mercerized undyed yarn into a solution comprising sulfur dyestuff before an initial immersion of the mercerized undyed yarn into an indigo dye solution. 
 
     
     
         20 . The method of  claim 13  wherein sulfur bottoming is not performed on the undyed yarn.