US 2007/0163950 A1 · High-flux dialysis membrane with improved separation behaviour

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 porous separating layer and an open-pored supporting layer adjoining the separating layer, and has an ultrafiltration rate in albumin solution of 25 to 60 ml/(h·m2·mmHg). The hollow-fibre membrane is free from pore-stabilising additives, and has a minimum sieving coefficient for cytochrome c of 0.8 and maximum sieving coefficient for albumin of 0.005. Method for the preparation of such membranes based on coagulation induced by a non-solvent, whereby a spinning solution of a synthetic first polymer and possibly a hydrophilic second polymer is extruded into a hollow fibre through the annular slit of a hollow-fibre die with simultaneous extrusion of a coagulation medium as the interior filler through the central opening of the hollow-fibre die, the interior filler initiating coagulation in the interior of the hollow fibre as a result of which a separating layer on the inner surface of the hollow-fibre membrane is formed as well as the membrane structure, the method being characterised in that the interior filler contains a polyelectrolyte with negative fixed charges.

Claims20

Dependent claims

A hydrophilic, water-wettable, semipermeable hollow-fibre membrane, based on a synthetic first polymer, particularly for hemodialysis, hemodiafiltration and hemofiltration, the membrane possessing an open-pored, integrally asymmetric structure across its wall, a porous separating layer with a thickness of 0.1 to 2 urn on its inner surface facing the lumen, and an open-pored supporting layer adjoining the separating layer, and having an ultrafiltration rate in albumin solution in the range of 25 to 60 ml/(h-m2-mmHg), characterised in that, after prior drying, the hollow-fibre membrane has a minimum sieving coefficient for cytochrome c of 0.8 combined with a maximum sieving coefficient for albumin of 0.005, whereby the hollow-fibre membrane in the dry state is free from pore-stabilising additives in the membrane wall.

A method for producing a hydrophilic, water-wettable, semipermeable hollow-fibre membrane, the method comprising the following steps:

a. preparing a homogeneous spinning solution comprising 12 to 30 wt. % of a synthetic first polymer and, if applicable, other additives in a solvent system,
b. extruding the spinning solution through the annular slit of a hollow-fibre die to give a hollow fibre,
c. extruding an interior filler through the central opening of the hollow-fibre die, the interior filler being a coagulation medium for the synthetic first polymer and comprising a solvent and a non-solvent for the synthetic first polymer,
d. bringing the interior filler into contact with the inner surface of the hollow fibre, to initiate coagulation in the interior of the hollow fibre and for formation of a separating layer on the inner surface of the hollow fibre and formation of the membrane structure,
e. passing the hollow fibre through a coagulation bath to complete the formation of the membrane structure if necessary, and to fix the membrane structure,
f. extracting the hollow-fibre membrane thus formed, to remove the solvent system and soluble substances,
g. drying the hollow-fibre membrane, characterised in that the interior filler contains a polyelectrolyte with negative fixed charges, as a result of which a hollow-fibre membrane is obtained with a minimum sieving coefficient for cytochrome c of 0.80 combined with a maximum sieving coefficient for albumin of 0.005.

4 more elements

Dependencies are inferred from the claim text.

High-flux dialysis membrane with improved separation behaviour

Life of this patent

High-flux dialysis membrane with improved separation behaviour

Life of this patent

Abstract

Claims20