Dialysis membrane having improved average molecular distance

Abstract

A hydrophilic semipermeable hollow-fibre membrane for blood treatment, with an integrally asymmetric structure based on a synthetic polymer. The hollow-fibre membrane possesses on its inner surface a separating layer and an adjoining open-pored supporting layer, and has an ultrafiltration rate in albumin solution of 5 to 25 ml/(h·m2·mmHg). The hollow-fibre membrane is free from pore-stabilizing additives and has a maximum sieving coefficient for albumin of 0.005 and a sieving coefficient for cytochrome c that satisfies the equation SCCC≧5·10−5·UFRAlb3−0.004·UFRAlb2+1.081·UFRAlb−0.25 A method for producing such membranes by a coagulation process induced by a non-solvent, in which a spinning solution comprising a synthetic first polymer and possibly a hydrophilic second polymer is extruded through the annular slit of a hollow-fibre die to give a hollow fibre, and a coagulation medium that initiates coagulation in the interior of the hollow fibre is simultaneously extruded through the central opening of the hollow-fibre die, the coagulation medium initiating coagulation in the interior of the hollow fibre for formation of a separating layer on the inner surface of the hollow fibre and formation of the membrane structure, the method being characterized in that the interior filler contains a polyelectrolyte with negative fixed charges.

Dependencies are inferred from the claim text.