Abstract Synthetic fibers, such as polypropylene fibers, are manufactured in a form in which the fibers are of regular dimensions and substantially free from whiskery appendant fibrils, by a controlled fibrillation method which comprises impressing in a web of the polymer composition at a temperature above its crystalline melting point a plurality of grooves disposed in close but spaced-apart relationship to the longitudinal direction of the web by passing the web at said temperature between two rollers having non-yielding surfaces, e.g. steel rollers, at least one of which bears closely spaced, parallel surface ridges each having inwardly directed sides leading to peaks which are rounded off to a small radius, the sides of adjacent ridges forming troughs, chilling the grooved web, and subjecting the chilled web to a fibrillation treatment including stretching said web to orient the polymer.
Apparatus suitable for use in the manufacture of synthetic fibers which comprises 1. a web profiling unit comprising (a) a pair of cooperating rotatable rollers having non-yielding surfaces, at least one of said rollers being adapted to be driven and having a plurality of closely spaced, parallel, surface ridges each having inwardly directed sides leading to a peak, the sides of adjacent ridges forming troughs, the profile of the ridges being such that the pitch of the ridges is within the range 0.003 to 0.05 inches and the depth of the troughs between adjacent ridges is within the range 0.002 to 0.02 inches, and (b) a means for effecting pressure contact between a moving polymer web at a temperature above its crystalline melting point and said roller pair, and 2. a unitary means for uniaxially stretching and fibrillating the profiled polymer web from said profiling unit.
Claim 2
Dependent Claim
146 words
Apparatus suitable for use in the manufacture of synthetic fibers which comprises 1. a web profiling unit comprising (a) a pair of cooperating rotatable rollers having non-yielding surfaces, at least one of said rollers being adapted to be driven and having a plurality of closely spaced, parallel, surface ridges each having inwardly directed sides leading to a peak, the sides of adjacent ridges forming troughs, the profile of the ridges being such that the pitch of the ridges is within the range 0.003 to 0.05 inches and the depth of the troughs between adjacent ridges is within the range 0.002 to 0.02 inches, and (b) a means for effecting pressure contact between a moving polymer web at a temperature above its crystalline melting point and said roller pair, and 2. a unitary means for uniaxially stretching and fibrillating the profiled polymer web from said profiling unit.
Claim 3
Dependent Claim
16 words
a unitary means for uniaxially stretching and fibrillating the profiled polymer web from said profiling unit.
Claim 4
Dependent Claim
16 words
a unitary means for uniaxially stretching and fibrillating the profiled polymer web from said profiling unit.