Process for making hollow fibers
AssigneeShell Oil Company
InventorFrank M. Aspin
Life of this patent
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Abstract
Process and apparatus for the manufacture of hollow fibers are disclosed in which at least two layers of molecularly orientable thermoplastic material are together passed through a pressure nip between two rollers, each of which has in its periphery annular grooves with lands therebetween, the grooves in the respective rollers being accurately aligned, whereby the layers are caused to form at least the boundaries of enlarged portions which are connected by thin integral portions or completely severed from each other. Any interconnected enlarged portions are then separated by mechanical means.
Claims6
A process for making hollow fibers which comprises (a) simultaneously passing at least two molecularly orientable plastic films through a pressure nip between two rollers, said plastic films being at or above their fusion temperature at least at the point where the films come in contact with said rollers, said rollers having from 15 to 60 peripheral annular grooves per inch with lands of no more than about 0.0015 inch width therebetween, the grooves in the respective rollers being accurately aligned so that the lands of each roller are in the same planes cutting the circumference of the roller, so that the films are fused together at the point they contact the lands and are kept apart by air trapped between the films in the non-fused area, (b) cooling the fused films below the fusion temperature of the molecularly orientable plastic, (c) stretching the fused films and treating the stretched film so as to cause the fused films to fibrillate.
Dependencies are inferred from the claim text.