HOLLOW FIBER CAPILLARY MEMBRANE AND METHOD FOR THE PRODUCTION THEREOF

• US 20100163488A1
• Filed: 04/21/2008
• Published: 07/01/2010
• Est. Priority Date: 04/23/2007
• Status: Active Grant

• Current Assignee: Holger Lichau, Igor Raiko, Klaus Heilmann, Rainer Fislage, Roland Sander, Torsten Keller
• Original Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius SE & Co. KGaA)
• Inventors: Sander, Roland, Keller, Torsten, Heilmann, Klaus, Lichau, Holger, Raiko, Igor, Fislage, Rainer
• Granted Patent: US 9,149,770 B2
• Time in Patent Office: Days
• US Class Current: 210/646
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: B01D 2325/0283 Pore size
• CPC Class Codes: B01D 61/027 Nanofiltration
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 69/088 Co-extrusion; Co-spinning
• CPC Class Codes: B01D 69/1212 Coextruded layers
• CPC Class Codes: B01D 71/441 Polyvinylpyrrolidone
• CPC Class Codes: B01D 71/68 Polysulfones; Polyethersulfones

Abstract

A hollow fiber membrane made of two coextruded layers A and B, wherein layer B has a non-woven type structure having a mesh size of 0.1 to 10 μm and layer A has a porous structure. A method for producing a membrane according to the invention and the use thereof is also disclosed.

Claims

1. Hollow fibre membrane, consisting of two co-extruded layers A and B, wherein layer B has a non-woven type structure with a mesh size of 0.1 to 10 μ

m and layer A has a porous structure.

2. Hollow fibre membrane according to claim 1, wherein layer A consists of at least 3 zones A1, A2, A3 of different porosity.

3. Hollow fibre membrane according to claim 2, wherein zone A1 forms the surfaces of layer A and has pores with an average pore size of 0.7-2 μ

m.

4. Hollow fibre membrane according to claim 3, wherein zone A3 is adjacent to layer B and has a pore-size gradient towards layer B, wherein the pore size increases towards layer B.

5. Hollow fibre membrane according to claim 4, wherein zone A2 is arranged between zones A1 and A3 and has pore sizes of >

200 nm.

6. Hollow fibre membrane according to claim 1, wherein the internal diameter of the hollow fibre membrane is 280 to 400 μ

m.

7. Hollow fibre membrane according to claim 1, wherein the total wall width of the hollow fibre membrane is 40 to 80 μ

m.

8. Hollow fibre membrane according to claim 1, wherein the ratio of the layer thicknesses of layer A to layer B lies in the range of 4:

1 to 6;

1.

9. Hollow fibre membrane according to claim 1, wherein both layer A and layer B consist of a mixture of at least two polymers.

10. Hollow fibre membrane according to claim 9, wherein the polymers are selected from polysulfone (PSU), polyvinylpyrrolidone (PVP), polyethersulfone (PES), polyetherimide (PEI), polyamide (PA), polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide (PI), and/or polyurethane (PU).

11. Hollow fibre membrane according to claim 10, wherein the material of layers A and B is a mixture of polysulfone (PSU) and polyvinylpyrrolidone (PVP).

12. Hollow fibre membrane according to claim 11, wherein the elutable portion of free residual polyvinylpyrrolidone in the finished membrane is less than 5 mg/0.6-m² membrane surface.

13. Hollow fibre membrane according to claim 12, wherein the LDL screening coefficient of the hollow fibre membrane is greater than 0.9.

14. Method for the production of a hollow fibre membrane according to claim 1, comprising the steps of:

(a) preparing two spinning mass solutions A and B, wherein the viscosity of spinning mass solution A is higher than the viscosity of spinning mass solution B;

(b) setting the precipitation bath temperature at >

70°

C.;

(c) bringing the two spinning mass solutions A and B into contact with an internal precipitant through a hollow fibre spinneret;

(d) precipitating the hollow fibre membrane.

15. Method according to claim 14, wherein the viscosity of spinning mass solution A lies in the range of 8000 to 15000 mPa·

s.

16. Method according to claim 15, wherein spinning mass solution A contains 15 to 35% polysulfone, 4 to 8% polyvinylpyrrolidone, the remainder being precipitant.

17. Method according to claim 14, wherein the viscosity of spinning mass solution B is less than 1000 mPa·

s.

18. Method according to claim 17, wherein spinning mass solution B contains 8 to 14% polysulfone, 3 to 6% polyvinylpyrrolidone, the remainder being solvent.

19. Method according to claim 14, wherein the spinning speed is 200 to 400 mm/s.

20. Method according to claim 19, wherein the spinning block temperature is set to 50 to 90°

C.

21. Method according to claim 20, wherein the precipitant is a mixture of dimethylacetamide and water.

22. Use of a hollow fibre membrane according to claim 1 for separation processes in the nanofiltration and ultrafiltration ranges.

23. Use of a membrane according to claim 1 for haemodialysis, haemodiafiltration and haemofiltration.