| abstract |
Integral polyether sulfone membrane with a pore system open at the outer boundaries in the form of flat foils, tubular foils or hollow fibers with a maximum pore diameter of 0.02 µm to 2 µm, the pore system being continuously cellular with polyhedral symmetrically delimited cells and the cells from one surface to the other of the membrane are arranged asymmetrically, the asymmetry factor AF relating to the maximum pore diameter being 0.01 to 2.0, and the ratio of the maximum mean free path length of the flow path to the diameter of the maximum pore being greater than 3 and from one surface to the other surface the cell size changes evenly.n n n The membrane is produced by dissolving 12 to 35% by weight, based on the total solution, of polyether sulfone in a mixture consisting of 15 to 65 wt .-% ε-caprolactam, 0 to 85 wt .-% latent solvent, 0 to 15 wt .-% thickener and 0 to 50 wt .-% non-solvent, optionally up to 1 wt. % Auxiliaries, shaping the solution into flat films, tubular films or hollow fibers (these preferably with the aid of an internal liquid), and transfer into the solid phase and removal of the mixture forming the solvent.n n n The membrane is used for ultrafiltration and microfiltration. |