Knit-deknit yarn and method and apparatus for making same

Abstract

An improved heavy denier fibrillated polymer carpet yarn is densely knit, deknit and heat treated. An improved carpet face yarn is provided in an omnidirectional carpet pile.

We claim:  
     
         1 . A process for making a carpet face yarn comprising: 
 providing a fibrillated polypropylene yarn greater than 7000 in Denier;    knitting the yarn on a knitting machine with a needle spacing less than 0.75 inch to form a knitted fabric;    pulling the knitted fabric from the knitting machine;    heat treating the knitted fabric to set the yarn in a kinked form with a stitch length less than about one inch;    deknitting the fabric; and    heat treating the yarn in situ in the carpet.    
     
     
         2 . The process of  claim 1 , wherein the yarn is knit into a sock on a circular knitting machine with a circumferential needle spacing of less than 0.67 inch.  
     
     
         3 . The process of  claim 2 , wherein the yarn in the sock is heat set into an approximately sinusoidal form having a wavelength λ of about 0.5 inches or less.  
     
     
         4 . The process of  claim 3 , wherein the deknitted yarn is wound.  
     
     
         5 . The process of  claim 4 , wherein the deknitted yarn is essentially straightened during winding.  
     
     
         6 . The process of  claim 1 , wherein, after heat treatment in situ the yarn has a generally sinusoidal form and wherein the pile height of the carpet above the backing is at least as great as the wavelength,λ, of the yarn after the carpet is heat treated.  
     
     
         7 . The process of  claim 1 , wherein the yarn is from 7600 D to 8000 D.  
     
     
         8 . A carpet yarn for a carpet product having a pile height of about one inch or less, the yarn being polymeric in composition and having a Denier of at least 7000, wherein the yarn is heat set into a repeating curvilinear form with a repeat length in the carpet product approximately equal to or less than the pile height.  
     
     
         9 . The carpet yarn of  claim 8 , wherein the yarn is heat set into an approximately sinusoidal form and wherein the repeat length of yarn is on the average less than one inch.  
     
     
         10 . The carpet yarn of  claim 9 , wherein the yarn is from 7600 to 8000 D.  
     
     
         11 . Apparatus for making carpet yarn comprising: 
 a supply of polymer yarn of at least 7000 D;    an applicator for applying a lubricant to the yarn;    a multi-needle circular knitting machine for receiving the lubricated yarn and knitting the yarn into a sock with a needle spacing of less than ⅔ inch;    variable drive system to pull the sock from the knitting machine at a selectable tension to inhibit breakage of the knitting machine needles;    an autoclave for heat treating the sock; and    mechanism for winding the yarn as the sock is deknitted.    
     
     
         12 . The apparatus of  claim 11 , wherein the circular knitting machine is a 90 slot, 6.25 inch diameter knitting machine, configured with 30 needles, one in every third slot.  
     
     
         13 . The apparatus of  claim 11 , wherein the lubricant is a silicone or oil.  
     
     
         14 . The apparatus of  claim 11 , wherein the applicator is a rotating coating roller in a reservoir of lubricant.  
     
     
         15 . The apparatus of  claim 11 , wherein the knitted sock contains yarn formed in repeating loops of less than about ¼″ edge to edge.  
     
     
         16 . The apparatus of  claim 11 , wherein the yarn in the heat treated sock has a heat set, generally sinusoidal form.  
     
     
         17 . The apparatus of  claim 16 , further comprising means for heating yarn tufted in the carpet to cause it to partially recover its sinusoidal form.  
     
     
         18 . A carpet product comprising: 
 a backing, and    a carpet yarn tufted with the backing, the carpet yarn having a Denier of at least 7000 and having heat set, repeating open loops with a repeat length approximately equal to or less than a pile height of the carpet, wherein the yarn loops have an average amplitude comparable to a separation distance between tufts in the carpet.