False twist beaded yarn

Abstract

To make a monofilament yarn having synthetic polymeric materials, a multifilament or monofilament core yarn is coated with a polymer using a specially designed die during an extrusion process. Flow instabilities created in the die resulting in a yarn that develops a non-uniform cross-sectional beading of the coating material. The beaded material forms a helical pattern around the yarn core, producing a false twist effect.

1 . A polymeric coated yarn, comprising: 
 a core yarn strand; and    a polymeric coating over said core yarn strand;    wherein said coating is non-uniform along a radial direction of said strand.    
   
   
       2 . The yarn of  claim 1 , wherein said coating forms a helical bead along an axial direction of said strand.  
   
   
       3 . The yarn of  claim 2 , wherein said helical bead is non-uniformly distributed along the axial direction, thereby forming a zigzag appearance.  
   
   
       4 . The yarn of  claim 3 , wherein an outer edge of a radial cross section of said coating is substantially circular.  
   
   
       5 . The yarn of  claim 1 , wherein an outer edge of a radial cross section of said coating is substantially circular.  
   
   
       6 . The yarn of  claim 1 , wherein said core yarn strand comprises artificial fibers.  
   
   
       7 . The yarn of  claim 2 , wherein said core yarn strand comprises more than one filament.  
   
   
       8 . The yarn of  claim 7 , wherein each filament comprises a different type of fiber.  
   
   
       9 . The yarn of  claim 1 , wherein said core yarn strand comprises a material different from a polymeric material.  
   
   
       10 . The yarn of  claim 1 , wherein said coating is extruded over said core yarn strand.  
   
   
       11 . The yarn of  claim 10  further comprising a pigment, wherein the coating is extruded with said pigment.  
   
   
       12 . A polymeric yarn, comprising a single polymeric strand having an axial axis, wherein an outer surface of said strand is non-uniform along a radial direction from said axial axis.  
   
   
       13 . A method of coating yarn, comprising: 
 creating an instability in flow of a polymeric coating through a die attached to an extruder;    extruding a core yarn strand with said coating through said die; and    forming a non-uniform coating along a radial direction of said strand.    
   
   
       14 . The method of  claim 13 , further comprising varying one or more processing parameters from the group of extruder pressure, extruder barrel temperature, die temperature, and yarn draw speed.  
   
   
       15 . The method of  claim 13 , further comprising extruding a pigment with said core yarn strand and coating.  
   
   
       16 . The method of  claim 13 , further comprising cooling said coated yarn in a chilled water tank.  
   
   
       17 . The method of  claim 13 , further comprising rolling said coated yarn through nip rollers.  
   
   
       18 . A crosshead extrusion die for forming a polymeric coating over a strand of yarn, comprising: 
 a die head;    a feed zone to admit said strand and said coating;    a flow balance zone to orient a flow of said coating; and    a die cap having an orifice through which said coating and said strand is extruded, and a reservoir to create a flow instability in said coating;    wherein a non-uniform coating along a radial direction of said strand is formed.    
   
   
       19 . The die of  claim 18 , wherein said orifice is circular.  
   
   
       20 . The die of  claim 18 , wherein said die comprises more than one orifice to simultaneously extrude more than one polymeric coated strand of yarn.