Hollow Fiber Membrane and Method for Manufacturing Thereof
AssigneeGambro Lundia AB
InventorsBernd Krause, Hermann Gohl, Markus Hornung, Carina Kraft
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Abstract
The present invention concerns a semipermeable hollow fiber membrane having an outer wall surface, an inner wall surface and an interior lumen extending along the length thereof and having the selective layer on the outer wall surface with a surface roughness below 10 nm. According to the invention the membrane has the smallest pore size on the outer wall surface, and has an outer wall surface which is smooth, continuous and homogeneous in a nanoscopic scale and four to five distinct layers of different pore size and density. Further the present invention concerns a process for manufacturing thereof and the use thereof.
Claims24
A semipermeable hollow fiber membrane having an outer wall surface, an inner wall surface, and an interior lumen extending along the length thereof and having the selective layer on the outer wall surface, characterized by having the smallest pore size on the outer wall surface, and by having an outer wall surface which is smooth, continuous and homogeneous in a nanoscopic scale, being virtually devoid of roughness with a roughness parameter Ra and Rq of not more than 10 nm, the roughness being measured with the use of atomic force microscope (AFM), and calculating the roughness parameters Ra and Rq using following equations:
- R
- a
- =
- 1
- N
-
- ∑
- i
- =
- 1
- N
-
-
- Z
- i
-
- R
- q
- =
- 1
- N
-
- ∑
- i
- =
- 1
- N
-
- Z
- i
- 2
- with N being the total number of data points and Zi being the height of a data point above the average picture level, and wherein the membrane wall between the outer wall surface and the inner wall surface has at least four layers with different pore sizes and mass densities, and wherein the layer positioned closest to the middle of the membrane wall has a smaller pore size and a higher mass density than the two layers directly adjacent on each side of said layer positioned closes to the middle of the membrane.
(canceled)
A process for manufacturing a semipermeable hollow fiber membrane, comprising the steps of
- extruding a polymer solution through an outer ring slit of a hollow fiber spinning nozzle, simultaneously extruding a bore liquid through the inner bore of the hollow fiber spinning nozzle, into a precipitation bath, wherein
- the polymer solution contains 10-20 wt.-% of polysulphone (PSU), polyethersulphone (PES) or polyarylethersulphone (PAES), 2-15 wt.-% polyvinylpyrrolidone (PVP) and a solvent,
- the bore liquid contains 50-75 wt.-% of a solvent and 25-50 wt.-% of water,
- the precipitation bath contains 50-70 wt.-% of a solvent and 30-50 wt.-% of water and has a temperature within the range of 22-31° C., and
- the distance between a discharge outlet of the hollow fiber spinning nozzle and the surface of the precipitation bath is within the range of 0-10 cm.
(canceled)
Dependencies are inferred from the claim text.