Polymer filaments having profiled cross-section

Abstract

The invention provides a profiled polymer filament having an open hollow cross-sectional shape normal to the longitudinal axis of the filament, wherein the cross-section is dimensioned to prevent the filament from interlocking with a second filament of the same cross-section. The invention also provides methods of manufacture of such filaments by melt spinning a polyamide, and spinnerets suitable for use in melt spinning such filaments.

1 - 38 . (canceled)  
     
     
         39 . A process for making a polymer yarn comprising: 
 extruding a polyamide melt through a spinneret;    cooling the extruded melt in a cross flow of air to form solid filaments;    optionally passing the quenched filaments through a steam atmosphere, applying a fibre finish oil;    optionally interlacing the yarn, passing the yarn over feed roll and draw roll pair, said feed and draw rolls differing in surface speed by a fixed amount within the range of 10 to 100% of said feed roll;    treating the draw yarn to reduce the final yarn shrinkage for good yarn package formation; and    optionally applying a fibre finish oil, interlacing the yarn and winding up the filaments at a speed greater than 3000 m/min,    wherein the polymer yarn comprising at least a single profiled filament having an open hollow cross-sectional profile shape normal to the longitudinal axis of the filament, said cross-sectional profile shape having a central arcuate portion and first and second elongated leg portions, each of said leg portions having proximal and distal end portions, said proximal end portions joining to said central portion and said distal end portions joining to foot portions on each leg portion, said foot portions having a dimension F, said leg portions and said central arcuate portion defining an open portion, said leg portions oriented in a substantially parallel relationship, and said foot portions defining an aperture leading to said open portion; said aperture having a dimension D, wherein dimension D is less than dimension F,    and wherein the profiled single filament linear density is less than 20 dtex and the yarn elongation to break is about 20 to 50% and the tenacity is about 25 to 60 cN/tex.    
     
     
         40 . A process for making a polymer yarn comprising: 
 extruding a polyamide melt through a spinneret;    cooling the extruded melt in a cross flow of air to form a solid filament;    optionally passing the quenched filaments through a steam atmosphere, applying a fibre finish oil;    optionally passing the yarn over tension control rolls; and    optionally interlacing the yarn and winding up the filament at a speed greater than 3000 m/min,    wherein the polymer yarn comprising at least a single profiled filament having an open hollow cross-sectional profile shape normal to the longitudinal axis of the filament, said cross-sectional profile shape having a central arcuate portion and first and second elongated leg portions, each of said leg portions having proximal and distal end portions, said proximal end portions joining to said central portion and said distal end portions joining to foot portions on each leg portion, said foot portions having a dimension F, said leg portions and said central arcuate portion defining an open portion, said leg portions oriented in a substantially parallel relationship, and said foot portions defining an aperture leading to said open portion; said aperture having a dimension D, wherein dimension D is less than dimension F,    and wherein the profiled single filament linear density is less than 20 dtex and the yarn elongation to break is about 55 to 85% and the tenacity is about 25 to 40 cN/tex.