A method for manufacturing multiple channel membranes includes extruding a
polymer solution through an extrusion nozzle wherein several needles are
arranged through which a gas or liquid containing a coagulating agent is
injected during extrusion, wherein the outer side of the extruded material
is first brought into contact with a mild coagulation agent and
subsequently with a strong coagulation agent. By using the method a
membrane is obtained having parallel channels extending in extrusion
direction, in which an active layer is situated in the channels, whereas
the outer surface with respect to the active layer has no or hardly any
resistance to flows of liquid. By using the method it is possible to make
shapes, such as recessed portions, in the membrane circumference. Also
disclosed is the use of such membranes in filtration and separation
techniques.
