US 5,762,798 AGranted

Hollow fiber membranes and method of manufacture

AssigneeMinntech Corporation

InventorsRandal M. Wenthold, Robert T. Hall, II, Robert G. Andrus, Paul D. Brinda, Louis C. Cosentino, Robert F. Reggin, Daniel T. Pigott

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Abstract

An asymmetrical, microporous, hollow fiber membrane is made from a polymeric dope mixture of polysulfone and polyvinyl pyrrolidone dissolved in an aprotic solvent. The physical morphology of the hollow fiber membrane, i.e., the asymmetric microporous wall, is rapidly formed by passing the polymeric dope mixture through an outer annular orifice of a tube-in-orifice spinneret while simultaneously passing a precipitating solution through the central tube of the spinneret. The emerging hollow fiber travels substantially downward for about 0.01-10 m before submersion into a quenching bath. The asymmetrical, microporous, hollow fiber membrane is biocompatible and suitable for use in, for example, dialysis, hemodialysis, ultrafiltration, and water filtration applications.

Claims90

Dependent claims

An asymmetrical, microporous, hollow fiber comprising a mixture of polysulfone and polyvinyl pyrrolidone which is a product of a process comprising the steps of:

(a) passing, through an outer annular orifice of a tube-in-orifice spinneret, a polymeric solution comprising about 11 to 25 wt-% of a hydrophobic, polysulfone polymer and about 0.1 to 5 wt-% of a polyvinylpyrrolidone polymer dissolved in an aprotic solvent and having a viscosity of about 700 to 3500 cP to form an annular liquid, wherein the tube-in-orifice spinneret has an inner tube, said inner tube and said outer annular orifice each having a cross-sectional area such that the ratio of the respective cross-sectional areas of the outer annular orifice to the inner tube is about 5:1 or greater;
(b) simultaneously passing, through the inner tube of the tube-in-orifice spinneret, into the center of the annular liquid, a precipitating solution comprising:
(i) about 30 to 90 wt-% of a lower alcohol;
(ii) about 10 to 35 wt-% of water;
(c) passing the annular liquid and the precipitating solution in the center of the annular liquid through a vertical drop of at least about 1 meter in an atmosphere or an augmented atmosphere, wherein the precipitating solution interacts with the polymeric solution within the annular liquid to form an annular polymer precipitate;
(d) quenching the annular polymer precipitate in a bath to form a hollow fiber, wherein the spinneret and the quenching bath are separated by a vertical distance of at least about 1 meter;
and
(e) taking up the fiber at a rate of about 90 to 150% of the rate at which it is formed.

5 more elements

A process for the manufacture of an improved microporous hollow fiber membrane having improved flux and rewetting characteristics, the process comprising:

(a) passing, through an outer annular orifice of a tube-in-orifice spinneret, a polymeric solution comprising about 5 to 25 wt-% of a hydrophobic polysulfone polymer and about 1 to 25 wt-% of a hydrophilic polyvinylpyrrolidone polymer dissolved in an aprotic solvent and having a viscosity of about 100 to 10,000 cP to form an annular liquid, wherein the tube-in-orifice spinneret has an inner tube, said inner tube and said outer annular orifice each having a cross-sectional area such that the ratio of the respective cross-sectional areas of the outer annular orifice to the inner tube is about 5:1 or greater;
(b) simultaneously passing, through the inner tube of the spinneret, into the center of the annular liquid a precipitating solution comprising:
(i) about 0.1 to 100 wt-% of an organic solvent;
and
(ii) about 0.1 to 100 wt-% of water as a nonsolvent;
(c) passing the annular liquid and the precipitating solution in the center of the annular liquid through a vertical drop of at least about 1 meter in an atmosphere or an augmented atmosphere, wherein the precipitating solution interacts with the polymeric solution within the annular liquid to form an annular polymer precipitate;
(d) quenching the annular polymer precipitate in a quenching bath comprising from about 0.001 to 10 wt-% of a low molecular weight surfactant to form a hollow fiber, wherein the spinneret and the quenching bath are separated by a vertical distance of at least about 1 meter;
and
(e) taking up the fiber at a rate of about 90 to 150% of the rate at which it is formed;
wherein the fiber has a flux of at least 5.times.10.sup.-5 mL/min/cm.sup.2 /mmHg and rewets by maintaining said flux for at least five use and drying cycles.

7 more elements

A process for the manufacture of an improved microporous hollow fiber membrane having improved flux and rewetting characteristics, the process comprising:

(a) passing, through an outer annular orifice of a tube-in-orifice spinneret, a polymeric solution comprising about 5 to 25 wt-.% of a hydrophobic polysulfone polymer and about 1 to 25 wt-% of a hydrophilic polyvinylpyrrolidone polymer dissolved in an aprotic solvent and having a viscosity of about 100 to 10,000 cP to form an annular liquid, wherein the tube-in-orifice spinneret has an inner tube, said inner tube and said outer annular orifice each having a cross-sectional area such that the ratio of the respective cross-sectional areas of the outer annular orifice to the inner tube is about 5:1 or greater;
(b) simultaneously passing, through the inner tube of the spinneret, into the center of the annular liquid a precipitating solution comprising:
(i) about 0.1 to 100 wt-% of an organic solvent;
and
(ii) about 0.1 to 100 wt-% of water as a nonsolvent;
(c) passing the annular liquid and the precipitating solution in the center of the annular liquid through a vertical drop of at least about 1 meter in an atmosphere or an augmented atmosphere, wherein the precipitating solution interacts with the polymeric solution within the annular liquid to form an annular polymer precipitate;
(d) quenching the annular polymer precipitate in a quenching bath to form hollow fibers, wherein the spinneret and the quenching bath are separated by a vertical distance of at least about 1 meter;
(e) taking up the fibers at a rate of about 90 to 150% of the rate at which they are formed;
(f) cutting and forming the fibers into bundles;
and
(g) contacting the bundles with a solution comprising from about 0.001 to 10 wt-% of a low molecular weight surfactant;
wherein the resultant fibers have a flux of at least 5.times.10.sup.-5 mL/min/cm.sup.2 /mmHg, contain from about 1.0.times.10.sup.-5 g to about 0.1 g of surfactant per gram of fibers and rewet by maintaining said flux for at least five use and drying cycles.

9 more elements

A process for the manufacture of an improved microporous hollow fiber membrane having improved flux and rewetting characteristics, the process comprising:

(a) passing, through an outer annular orifice of a tube-in-orifice spinneret, a polymeric solution comprising about 5 to 25 wt-% of a hydrophobic polysulfone polymer, from about 0.001 to about 10 wt-% of a low molecular weight surfactant and about 1 to 25 wt-% of a hydrophilic polyvinylpyrrolidone polymer dissolved in an aprotic solvent, and having a viscosity of about 100 to 10,000 cP to form an annular liquid, wherein the tube-in-orifice spinneret has an inner tube, said inner tube and said outer annular orifice each having a cross-sectional area such that the ratio of the respective cross-sectional areas of the outer annular orifice to the inner tube is about 5:1 or greater;
(b) simultaneously passing, through the inner tube of the spinneret, into the center of the annular liquid a precipitating solution comprising:
(i) about 0.1 to 100 wt-% of an organic solvent;
and
(ii) about 0.1 to 100 wt-% of water as a nonsolvent
(c) passing the annular liquid and the precipitating solution in the center of the annular liquid through a vertical drop of at least about 1 meter in an atmosphere or an augmented atmosphere, wherein the precipitating solution interacts with the polymeric solution within the annular liquid to form an annular polymer precipitate;
(d) quenching the annular polymer precipitate in a bath to form a hollow fiber;
and
(e) taking up the fiber at a rate of about 90 to 150% of the rate at which it is formed;
wherein the fiber has a flux of at least about 5.times.10.sup.-5 mL/min/cm.sup.2 /mmHg and rewets by maintaining said flux for at least five use and drying cycles.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/058,904Filed 6 May 1993 · continuation in part
Priority: 12 Apr 1991
Granted: 9 Jun 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification33 codes

B01D 71/64
Polycondensates having nitrogen-containing heterocyclic rings in the main chain: polyimides; Polyamide-imides; Polyester-imides; Polyamide acids…
A61M 1/1672
Apparatus for preparing dialysates: using membrane filters, e.g. for sterilising the dialysate
B01D 61/30
Dialysis ; Membrane extraction: accessories; Auxiliary operation
B01D 69/02
Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes…:…