Hollow fibres

Abstract

A hollow fiber is provided possessing a continuous longitudinally extending channel free from macromolecular material, said fiber consisting essentially of a copolymer of acrylonitrile and an olefinically unsaturated comonomer containing an optionally salified sulphonic acid group, and possessing micropores of average diameter less than about 100 A, between 40% and 80% of walls of the fiber being empty space. This fiber can be prepared by injecting a solution of a copolymer of acrylonitrile and an olefinically unsaturated comonomer containing an optionally salified sulphonic acid group in at least one polar organic solvent into a spinneret with an annular orifice, and immediately coagulating the inside and the outside of the nascent hollow fibre issuing from the spinneret with a coagulating fluid which is selected from: A. a less than saturated aqueous solution of an inorganic salt, said solution optionally containing up to 40% of a miscible polar organic solvent, and B. at least one polar organic solvent which is a non-solvent for the acrylonitrile copolymer and is miscible with the solvent for the copolymer, the coagulation inside the fiber being carried out by injecting coagulating fluid inside the nascent fiber. Such fibers possess excellent permeability to water which makes them particularly useful in ultrafiltration as well as dialysis, especially haemodialysis.

Dependencies are inferred from the claim text.