| abstract |
In a process for preparing an open-pored polysulphonamide microfiltration membrane, a film is formed from a pouring solution of a polysulphonamide in a polar solvent, a precipitant for the polymer, possibly a pore former and a swelling agent. The film is then treated as follows: before it is immersed in the precipitant bath, a current of air at a temperature of at least 20 DEG C is passed over it, and it is then coagulated with a liquid which is miscible with the polar organic solvent but is nevertheless a precipitant for the polysulphonamide. The membrane obtained by this process, which possesses a foam structure, has a pore size between 0.1 and 5 mu m, which increases continuously from one side to the opposite side. The membrane can be wetted with water and is used preferably for static filtration. |