Oriented profile fibers

Claim 1

Oriented non-circular fibers comprising elongate spun fibers having a non-circular cross-section defined by: SRF=X.sub.orf /X.sub.fib <1.3 where X is defined as the ratio of the fiber or orifice cross-sectional area (A) to the square of the fiber or orifice diameter (D), and SRF2=Y.sub.orf /Y.sub.fib <3.5 for fibers formed from dies where Y orf /4π>20, or SRF2=Y.sub.orf /Y.sub.fib <2.0 for fibers formed from dies where Y orf /4π<20, where Y is defined as the ratio of the fiber or orifice perimeter squared to the fiber or orifice cross-sectional area, said fibers formed by a process comprising the steps of: heating at least a portion of a contained flow path formed by a conduit means, said flow path defining conduit means having at least one thermoplastic material inlet and at least one thermoplastic material outlet, providing a non-circular profiled orifice at said at least one thermoplastic material outlet which orifice is in communication with a second fluid region, passing a thermoplastic material through said heated portion of said contained flow path such as to heat said material to a temperature about 10°-90° C. above its crystalline phase transition temperature or minimum flow viscosity to form a fluid thermoplastic stream, forming said fluid thermoplastic stream into a profiled stream substantially corresponding to the shape of said orifice while passing said stream from said flow path into said second fluid region, orienting said profiled stream in said second fluid region by drawing said profiled stream at a draw down rate of at least 10 while cooling said profiled stream with a quenching fluid in said second fluid region, wherein a fiber is formed having a profile substantially identical to that of said profiled thermoplastic stream.