Abstract: A process for the production of a porous organic material, in particular a semi-permeable membrane, comprising a plurality of separate passageways, including dissolving a polymer in a solvent, using a drawplate having needles of a shape conjugate with those of the passageways and of external dimensions between 0.7 and 1.2 times those of the passageways and an extrusion orifice of a shape conjugate those of the extrudate and of internal dimensions comprising between 0.8 and 1.2 times those of the extrudate, injecting around the needles a solution having a viscosity greater than 500 mPa.s and introducing a centering fluid into the interior of these needles, recovering the extrudate at the output of the drawplate in a precipitating medium in such a manner that the extrudate travels in the medium a distance such that 800.times.

Abstract: The invention relates to an extrusion plate for the production of membranes of an organic material including at least one longitudinal passageway. This extrusion plate includes an annular body (1) provided with a cylindrical cavity into which opens at least one radial fluid conduit (5), an upper ferule (3) adapted to be inserted into the cavity of the body and comprising at least one hollow needle (8) extending in the extension of said insert and a longitudinal centering fluid feed conduit (9), and a lower insert (4) adapted to be inserted into the cavity of the body and having a bore (6) defining an extrusion chamber around the needles (8). The upper (3) and lower (4) inserts are in abutment at assembly faces at the level of which open the fluid conduits (5), and a fluid passage (7) is provided on these opposing faces in continuity with the passages (5), for communicating with the extrusion chamber.