Apparatus and method for multicomponent fibers

Abstract

Disclosed herein is an apparatus for forming sheath-and-core fibers, the apparatus comprising a series of stacked distribution plates comprising channels arranged to convey first and second fluidized polymers separately and comprising a restriction zone for distributing the second fluidized polymer around the first polymer as a sheath. Also disclosed is a method for forming such sheath-and-core fibers. The apparatus and method are well suited to forming sheath-and-core fibers having very low percentage of sheath component.

1 . An apparatus for the production of extruded multicomponent fibers, said apparatus comprising: 
 a) a series of stacked distribution plates, said stacked distribution plates comprising channels arranged to conduct a first fluid along at least one vertical flow path, and said stacked distribution plates comprising channels arranged to conduct a second fluid along first and second lateral flow paths, then along a plurality of vertical paths, then along a second plurality of lateral paths, then along a second plurality of vertical paths, said second plurality of vertical paths terminating in an annular-shaped lateral channel;    b) a restriction zone for receiving said second fluid from said annular-shaped lateral channel, said restriction zone arranged between two of said stacked distribution plates; and,    c) a spin plate comprising at least one extrusion capillary arranged to receive said first fluid and said second fluid.    
   
   
       2 . The apparatus of  claim 1  wherein said fiber is a sheath-and-core fiber having a fiber cross-sectional area comprising a sheath cross-sectional area and a core cross-sectional area, and wherein said restriction zone is adapted to result in a substantially continuous sheath around said core and wherein said sheath cross-sectional area is less than about 25 percent of said fiber cross-sectional area.  
   
   
       3 . The apparatus of  claim 2  wherein said sheath cross-sectional area is less than about 20 percent of said fiber cross-sectional area.  
   
   
       4 . The apparatus of  claim 3  wherein said sheath cross-sectional area is less than about 15 percent of said fiber cross-sectional area.  
   
   
       5 . The apparatus of  claim 4  wherein said sheath cross-sectional area is 10 percent or less of said fiber cross-sectional area.  
   
   
       6 . The apparatus of  claim 1  wherein said restriction zone comprises a depth and a width and wherein said depth is from about 0.05 millimeters to about 0.4 millimeters, and wherein said width is from about 0.5 millimeters to about 3.0 millimeters.  
   
   
       7 . The apparatus of  claim 6  wherein said depth is from about 0.05 millimeters to about 0.15 millimeters, and wherein said width is from about 1.0 millimeter to about 2.0 millimeters.  
   
   
       8 . An apparatus for the production of extruded multicomponent fibers, said apparatus comprising: 
 a) at least one extrusion capillary;    b) a first distribution plate configured to conduct a first polymer along a vertical central path, and configured to conduct a second polymer along first and second lateral paths, then along a plurality of vertical paths, then along a plurality of lateral paths;    c) a second distribution plate configured to conduct said first polymer along a vertical path, and configured to conduct said second polymer along a plurality of vertical paths, then along a plurality of lateral paths, said lateral paths forming an annular path, and said second distribution plate forming the upper portion of a restriction zone; and    d) a third distribution plate forming the lower portion of said restriction zone and said third distribution plate configured to conduct said first polymer and said second polymer to said extrusion capillary.    
   
   
       9 . A method for forming a sheath-and-core multicomponent fiber, said method comprising: 
 a) providing a plurality of stacked distribution plates and a spin plate comprising a plurality of extrusion capillaries;    b) providing a first fluidized polymer and a second fluidized polymer;    c) conveying said first polymer along a first vertical path through said stacked distribution plates to said extrusion capillary;    d) conveying said second polymer along second paths through said stacked distribution plates, said second paths terminating in an annular-shaped lateral channel;    e) conveying said second polymer through a restriction zone between said annular-shaped lateral channel and said first vertical path to envelop said first polymer with said second polymer; and    f) extruding said first polymer and said second polymer from said extrusion capillary.    
   
   
       10 . The method of  claim 9  wherein said first fluidized polymer and said second fluidized polymer are molten thermoplastic polymers.  
   
   
       11 . The method of  claim 10  wherein said first fluidized polymer is an elastomeric polymer.  
   
   
       12 . The method of  claim 11  wherein said second fluidized polymer is polyolefin.  
   
   
       13 . The method of  claim 9  wherein said sheath-and-core fiber comprises a fiber cross-sectional area comprising a sheath cross-sectional area and a core cross-sectional area, and wherein said restriction zone is adapted to result in a substantially continuous sheath around said core and wherein said sheath cross-sectional area is less than about 25 percent of said fiber cross-sectional area  
   
   
       14 . The method of  claim 13  wherein said sheath cross-sectional area is less than about 15 percent of said fiber cross-sectional area.  
   
   
       15 . The method of  claim 14  wherein said sheath cross-sectional area is 10 percent or less of said fiber cross-sectional area.  
   
   
       16 . A sheath-and-core fiber produced in accordance with the method of  claim 9 .  
   
   
       17 . A nonwoven web comprising a plurality of the fibers of  claim 16 .  
   
   
       18 . A sheath-and-core fiber produced in accordance with the method of  claim 11 .  
   
   
       19 . A nonwoven web comprising a plurality of the fibers of  claim 18 .  
   
   
       20 . A sheath-and-core fiber produced in accordance with the method of  claim 15.