Manufacture of synthetic fibers and yarns

Claim 1

In the process for the manufacture of synthetic fibers of regular dimension and substantially free from whiskers which comprises bringing a sheet-like mass of a molecularly-orientable thermoplastic material at a temperature above its crystalline melting point into pressure contact with a profiling element to form a profiled polymer web having a plurality of longitudinal grooves disposed in close but spaced apart relationship in at least one surface thereof, said profiling element having a plurality of closely spaced, parallel, surface ridges each having inwardly directed sides leading to a peak, chilling the profiled web and stretching to effect orientation thereof, and subjecting the profiled molecularly oriented web to a controlled fibrillation to form said synthetic fibers, the improvement which comprises contacting the ungrooved surface of the profiled web while above its crystalline melting point with a chill roller which is drivably mounted in a position below the profiling element such that the profiled web travels substantially vertically downwards to impinge tangentially on the roller surface, thereby chilling the profiled web to a temperature below the melting point of the polymer, while at the same time imparting a drawing movement to the web parallel with the direction of extrusion between the profiling element and the chill roller, thereby subjecting the web to a melt draw-down parallel to the direction of extrusion and reducing the cross-sectional area of the profile web.