Carpet yarn desensitized to variable ambient environmental conditions and methods and systems of making the same

Abstract

Carpet yarn is provided which is significantly less sensitive to changing ambient environmental conditions. As such, the carpet yarns exhibit substantially uniform wet bulk properties across a wide range of ambient temperature and/or atmospheric moisture conditions so as to reduce significantly (if not eliminate entirely) visible streaks in carpets formed of such yarns. In especially preferred embodiments, the carpet yarns when made are subjected to a substantially higher draw ratio and a substantially higher precrimp temperature prior to being brought into contact with water supplied by means of a non-peristaltic, continuous pressure, steady stream pump. The resulting yarn moisture content is increased to a greater level as compared to conventional carpet yarns not possessing the environmental desensitivity exhibited by the yarns of the present invention.

1 . A method of making environmentally desensitized polymeric yarn comprising the sequential steps of: 
 (i) melt-spinning a polymer to form a multi-filament yarn;    (ii) drawing and texturizing the melt-spun yarn;    (iii) applying an environmentally desensitizing sufficient amount of water to the drawn and textured yarn by bringing the yarn into contact with a substantially constant flow of water supplied to the yarn by a non-peristaltic pump; and thereafter    (iv) collecting the drawn and texturized yarn.    
   
   
       2 . The method of  claim 1 , wherein step (iii) is practiced so as to apply greater than about 3.5 wt. % water add-on to the yarn, based on total yarn weight.  
   
   
       3 . The method of  claim 2 , wherein the water add-on is between about 4 to about 10 wt. %.  
   
   
       4 . The method of  claim 2 , wherein the water add-on is between about 5.0 to about 8.0 wt. %.  
   
   
       5 . The method of  claim 2 , wherein the step (i) comprises melt-spinning a nylon-6 or nylon 6,6 polymer, and wherein the water add-on according to step (iii) is between about 6.0 to about 7.0 wt. %.  
   
   
       6 . The method of  claim 1 , wherein step (ii) is practiced by drawing the yarn between first and second heated rolls to achieve a draw ratio of between about 1.4 to about 3.6.  
   
   
       7 . The method of  claim 6 , comprising heating the first and second rolls so that the second roll is between about 70° C. to about 190° C. greater than the first roll.  
   
   
       8 . The method of  claim 7 , wherein the multifilament yarn is nylon-6 and wherein the first roll is heated to a temperature of between about 50 to about 70° C., and wherein the second roll is heated to a temperature between about 170 to about 200° C.  
   
   
       9 . The method of  claim 7 , wherein the multifilament yarn is nylon 6,6 and wherein the first roll is heated to a temperature of between about 50 to about 100° C., and wherein the second roll is heated to a temperature between about 170 to about 240° C.  
   
   
       10 . The method of  claim 1 , wherein step (iv) comprising winding the yarn onto a spool.  
   
   
       11 . The method of  claim 10 , further comprising the step of (v) placing the yarn spool in a moisture controlled environment.  
   
   
       12 . The method of  claim 11 , wherein said step (v) comprises wrapping the yarn spool in a moisture-proof plastics film.  
   
   
       13 . A system for making environmentally desensitized polymeric yarn comprising: 
 a melt-spinning unit to form a melt-spinnable polymer into multi-filament yarn;    a draw texturing unit for drawing and texturizing the melt-spun yarn;    a water applicator unit for applying an environmentally desensitizing sufficient amount of water to the drawn and textured yarn, said water applicator unit comprising a yarn guide having a surface against which the yarn is adapted to contact, an aperture having an opening onto the yarn guide surface to allow water to contact the yarn, and a non-peristaltic pump for supplying a substantially constant flow of water to the aperture in the yarn guide; and    (iv) a winder for collecting the drawn and texturized yarn.    
   
   
       14 . The system of  claim 13 , wherein said draw texturing unit comprises first and second heated rolls operable to achieve a draw ratio of between about 1.4 to about 3.6.  
   
   
       15 . The system of  claim 13 , wherein the water applicator unit comprises a stationary applicator guide having a convex guide surface for guiding the drawn and textured yarn, an inlet port for receiving the constant uninterrupted stream of water from the non-peristaltic pump, and a supply channel fluid-connecting the inlet port to the guide surface wherein water is supplied to the drawn and textured yarn being guided thereby.  
   
   
       16 . The system of  claim 15 , further comprising a head tank for providing an available supply of water to the nonperistaltic pump at substantially a constant pressure.  
   
   
       17 . The system of  claim 16 , wherein the head tank maintains the supply of water at a relatively low pressure of less than about 10 inches-H 2 O.  
   
   
       18 . A drawn and textured yarn exhibiting less environmental sensitivity which is made by the method of any one of claims  1 - 9 .  
   
   
       19 . A yarn spool made by the method of any one of claims  10 - 13 .