Patent US4722795A successfully refreshed from Google Patents.
US4722795A
Expired / Lapsed
US
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Polyamide hollow fiber filtration membrane having barrier layer
Assignee: Gambro Dialysatoren GmbH and Co KG
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Filing: 1985-09-30
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Granted: 1988-02-02
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Expires: 2005-09-30
Abstract
Abstract A filtration membrane is disclosed which has an ultrafiltration rate of between 200×10 -4 and 500×10 -4 ml/sec.×cm 2 ×bar at 20° C. and which is substantially impermeable to albumin of a molecular weight of about 44,000 or greater. A process for producing a filtration membrane is also disclosed in which a polymer solution is extruded with a center liquid under conditions such that the ratio of the volume of polymer solution to the volume of center liquid is within the range of from about 2:1 to about 4:1 to form a membrane extrudate.
Inventors
- 👤 Hermann J. Gohl
- 👤 Georg B. Mayer
- 👤 Gunther F. Geiling
- 👤 Claes-Ake Gullberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:44
CPC Classifications
D; D01; D01D; D01D5/00; D01D5/24; B; B01; B01D; B01D69/00; B01D69/02; B01D69/08; B01D71/00; B01D71/06; B01D71/56
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
177 words
A filtration membrane in the form of a hollow fiber prepared by extruding a polymer solution containing a bicompatible polyamide in the form of a hollow fiber in an amount of from 5 to 20% by weight and having a viscosity of 100 to 3000 cps. measured at 20° C. in the presence of a center liquid so as to provide a hollow fiber membrane having a barrier layer on one surface thereof, an inner diameter to wall thickness ratio within the range of from about 2.9:1 to 4.1:1 and having an ultrafiltration rate for water of between 200×10 -4 and 500×10 -4 ml/sec.×cm 2 ×bar at 20° C., said polyamide having repeating units of the following chemical formula: ##STR2## wherein R 1 is hydrogen and R 2 , R 3 and R 4 are independently selected lower-alkyl groups, or wherein R 3 is hydrogen and R 1 , R 2 and R 4 are independently selected lower-alkyl groups, said hollow fiber membrane being substantially impermeable to albumin of a molecular weight of about 44,000 or greater.
Claim 2
Dependent Claim
177 words
A filtration membrane in the form of a hollow fiber prepared by extruding a polymer solution containing a bicompatible polyamide in the form of a hollow fiber in an amount of from 5 to 20% by weight and having a viscosity of 100 to 3000 cps. measured at 20° C. in the presence of a center liquid so as to provide a hollow fiber membrane having a barrier layer on one surface thereof, an inner diameter to wall thickness ratio within the range of from about 2.9:1 to 4.1:1 and having an ultrafiltration rate for water of between 200×10 -4 and 500×10 -4 ml/sec.×cm 2 ×bar at 20° C., said polyamide having repeating units of the following chemical formula: ##STR2## wherein R 1 is hydrogen and R 2 , R 3 and R 4 are independently selected lower-alkyl groups, or wherein R 3 is hydrogen and R 1 , R 2 and R 4 are independently selected lower-alkyl groups, said hollow fiber membrane being substantially impermeable to albumin of a molecular weight of about 44,000 or greater.
Claim 3
Dependent Claim
29 words
A membrane according to claim 1, wherein said membrane has a wall thickness of from 40 to 100 μm and has a molecular weight cut-off of about 30,000 Daltons.
Claim 4
Dependent Claim
13 words
A filtration membrane according to claim 1, wherein the membrane has been washed.
Claim 5
Dependent Claim
26 words
A filtration membrane according to claim 1, wherein said polymer solution comprises said polymer and a polar, non-protonic, organic solvent in which said polymer is soluble.
Claim 6
Dependent Claim
19 words
A filtration membrane according to claim 4, wherein said polymer solution contains about 11% by weight of said polymer.
Claim 7
Dependent Claim
14 words
A filtration membrane according to claim 1, wherein said lower-alkyl groups are methyl groups.
Claim 8
Dependent Claim
22 words
A filtration membrane according to claim 1, wherein said polymer solution has a viscosity of about 300 cps. measured at 20° C.
Claim 9
Dependent Claim
51 words
A filtration membrane according to claim 1, wherein said polymer solution is extruded with a center liquid under conditions such that the ratio of the volume of polymer solution to the volume of center liquid is within the range of from about 1.4:1 to about 4:1 to form a membrane extrudate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-01 | 1991-08-03 | 1992-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-01 | 1995-08-03 | 1996-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-01 | 1999-08-03 | 2000-02-02 | $7700.00 | Window Closed / Lapsed |