Crosslinked hollow-fibre membranes and new process for manufacturing the same

A process for manufacturing a hollow-fibre membrane, comprising:

• (a) spinning a hollow-fibre membrane by:
• (a1) extruding through an orifice of a hollow-fibre die a phase (a1) composition comprising:
• (a1.i) a polymer selected from the group consisting of:
• polyimides, copolyimides;
• block-copolyimides;
• polyetherimides;
• polyamidoimides;
• and mixtures and blends thereof;
• and
• (a1.ii) a solvent or a solvent mixture for said polymer (a1.i);
• (a2) co-extruding through a central orifice of the hollow-fibre die and/or through an outer orifice of a hollow-fibre die a phase (a2) composition comprising:
• (a2.i) an amine based crosslinker, with at least two amino groups;
• (a2.ii) a non-solvent or a non-solvent mixture for the polymer (a1.i);
• (b) passing the hollow-fibre membrane through a coagulation bath;
• (c) drying the hollow-fibre membrane to an overall water and/or residual solvent content of from 0% to 5% by weight;
• (d) thermally treating the hollow-fibre membrane at an annealing temperature of 150 to 280° C.;
• wherein annealing takes place in a surrounding atmosphere with less than 0.5% oxygen by volume.