US4364759A
Expired / Lapsed
US
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Methods for preparing anisotropic hollow fiber membranes comprising polymer of acrylonitrile and styrene and hollow fiber membranes produced therefrom
Assignee: Permea Inc
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Filing: 1980-02-20
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Granted: 1982-12-21
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Expires: 2000-02-20
Abstract
Abstract Anisotropic hollow fiber membranes comprising polymer of acrylonitrile and styrene are prepared by extruding a solution of a hollow fiber-forming polymer comprising polymer of acrylonitrile and styrene in a liquid carrier through an annular spinnerette to form a hollow fiber precursor, and the hollow fiber precursor is coagulated in a liquid coagulant comprising water to form a hollow fiber membrane. The liquid carrier used in the method comprises N,N-dimethylformamide and preferably contains non-solvent for the polymer of acrylonitrile and styrene. The hollow fiber membranes have a homogeneously-formed thin selective skin on an open cellular support and exhibit high resistance to collapse. The membranes are especially useful for the separation of gases.
Inventors
- 👤 Albert A. Brooks
- 👤 Jay M. S. Henis
- 👤 Mary K. Tripodi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:33
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0081; B01D67/0088; B01D69/00; B01D69/02; B01D69/08; B01D71/00; B01D71/06; B01D71/40; B01D71/42; B01D71/421; D; D01; D01D; D01D5/00; D01D5/24; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2973; Y10T428/2975
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
328 words
A dry, integral anisotropic hollow fiber membrane for the separation of at least one gas of a gaseous mixture comprising a homogeneously-formed, thin, exterior, separating layer on an open, cellular support and comprising polymer of acrylonitrile and styrene in which polymer, acrylonitrile comprises at least about 20 mole percent of said polymer and styrene comprises up to about 60 mole percent of said polymer, wherein a volume majority of the wall of said hollow fiber membrane consists of cells having a mean major dimension of less than about 2 microns and said open, cellular support comprising a substantial absence of macrovoids having a major dimension greater than about 3 microns and a ratio of maximum length to maximum width greater than about 10, said hollow fiber membrane exhibiting a ratio of permeability of at least one of hydrogen, helium and ammonia to the permeability constant of the material of the hollow fiber membrane for said gas of at least about 5×10 4 reciprocal centimeters; a permeability ratio of (i) the permeability of a lower molecular weight gas divided by the permeability of a higher molecular weight gas to (ii) the square root of the molecular weight of said lower molecular weight gas divided by the square root of the molecular weight of said higher molecular weight gas of at least about 6, wherein said lower molecular weight gas is one of hydrogen and helium and said high molecular weight gas is one of nitrogen, carbon monoxide and carbon dioxide and has a permeability constant in the polymer at least about 10 times less than the permeability constant of said lower molecular weight gas in said material; and a collapse pressure of at least about 4(T S )(t/D) 3 wherein T S is the tensile strength of the polymer, t is the wall thickness and D is the outside diameter of the hollow fiber membrane, said membrane having a permeability for water of less than about 0.05×10 -6 .
Claim 2
Dependent Claim
328 words
A dry, integral anisotropic hollow fiber membrane for the separation of at least one gas of a gaseous mixture comprising a homogeneously-formed, thin, exterior, separating layer on an open, cellular support and comprising polymer of acrylonitrile and styrene in which polymer, acrylonitrile comprises at least about 20 mole percent of said polymer and styrene comprises up to about 60 mole percent of said polymer, wherein a volume majority of the wall of said hollow fiber membrane consists of cells having a mean major dimension of less than about 2 microns and said open, cellular support comprising a substantial absence of macrovoids having a major dimension greater than about 3 microns and a ratio of maximum length to maximum width greater than about 10, said hollow fiber membrane exhibiting a ratio of permeability of at least one of hydrogen, helium and ammonia to the permeability constant of the material of the hollow fiber membrane for said gas of at least about 5×10 4 reciprocal centimeters; a permeability ratio of (i) the permeability of a lower molecular weight gas divided by the permeability of a higher molecular weight gas to (ii) the square root of the molecular weight of said lower molecular weight gas divided by the square root of the molecular weight of said higher molecular weight gas of at least about 6, wherein said lower molecular weight gas is one of hydrogen and helium and said high molecular weight gas is one of nitrogen, carbon monoxide and carbon dioxide and has a permeability constant in the polymer at least about 10 times less than the permeability constant of said lower molecular weight gas in said material; and a collapse pressure of at least about 4(T S )(t/D) 3 wherein T S is the tensile strength of the polymer, t is the wall thickness and D is the outside diameter of the hollow fiber membrane, said membrane having a permeability for water of less than about 0.05×10 -6 .
Claim 3
Dependent Claim
13 words
The hollow fiber membrane of claim 1 having a substantial absence of macrovoids.
Claim 4
Dependent Claim
35 words
The hollow fiber membrane of claim 1 in which at least about 90 volume percent of the wall of the hollow fiber membrane consists of cells having a major dimension less than about 2 microns.
Claim 5
Dependent Claim
35 words
The hollow fiber membrane of claim 1 in which at least about 90 volume percent of the wall of the hollow fiber membrane consists of cells having a major dimension less than about 1 micron.
Claim 6
Dependent Claim
32 words
The hollow fiber membrane of claim 1 in which the void volume of the wall of the hollow fiber membrane is at least about 40 and up to about 70 volume percent.
Claim 7
Dependent Claim
32 words
The hollow fiber membrane of claim 5 in which the void volume of the wall of the hollow fiber membrane is greater than about 45 and up to about 65 volume percent.
Claim 8
Dependent Claim
50 words
The hollow fiber membrane of claim 1 or 5 in which the collapse pressure of the hollow fiber membrane is greater than about 10 (φ)(T S )(t/D) 3 wherein φ is the volume fraction of the material of the hollow fiber membrane in the wall of the hollow fiber membrane.
Claim 9
Dependent Claim
117 words
The hollow fiber membrane of claim 1 or 5 which exhibits a relationship of (i) the quotient of the difference between the permeabilities of a more readily permeated gas and a less readily permeated gas divided by the permeability of the less readily permeated gas times (ii) the ratio of the permeability constant of the less readily permeated gas to the permeability constant of the more readily permeated gas of at least about 0.01, wherein the more readily permeated gas has a permeability constant at least about 5 times greater than the permeability constant of the less readily permeated gas and the more readily permeated gas and less readily permeated gas have approximately the same molecular weight.
Claim 10
Dependent Claim
21 words
The hollow fiber membrane of claim 1, 2 or 5 in which the external skin is less than about 1000 angstroms.
Claim 11
Dependent Claim
21 words
The hollow fiber membrane of claim 1, 2 or 5 in which the external skin is less than about 500 angstroms.
Claim 12
Dependent Claim
19 words
The hollow fiber membrane of claim 1 or 5 in which the permeability ratio is at least about 7.5.
Claim 13
Dependent Claim
29 words
The hollow fiber membrane of claim 1 in which the material of the hollow fiber membrane exhibits a tensile strength of at least about 350 kilograms per square centimeter.
Claim 14
Dependent Claim
19 words
The hollow fiber membrane of claim 1 wherein acrylonitrile comprises about 30 to 80 mole percent of the polymer.
Claim 15
Dependent Claim
27 words
The hollow fiber membrane of claim 1 or 13 wherein the polymer of acrylonitrile and styrene has a weight average molecular weight of about 75,000 to 500,000.
Claim 16
Dependent Claim
21 words
The hollow fiber membrane of claim 1, 2 or 13 wherein the polymer consists essentially of polymer of acrylonitrile and styrene.
Claim 17
Dependent Claim
33 words
The hollow fiber membrane of claim 2, 5 or 9 wherein styrene comprises about 10 to 50 mole percent of the polymer and acrylonitrile comprises about 30 to 80 percent of the polymer.
Claim 18
Dependent Claim
34 words
The hollow fiber membrane of claim 1, 2 or 13 wherein the outside diameter is about 300 to 800 microns and the ratio of wall thickness to outside diameter is about 0.15 to 0.4.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-12-20 | 1986-06-21 | 1986-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-12-20 | 1990-06-21 | 1990-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-12-20 | 1994-06-21 | 1994-12-21 | $7700.00 | Window Closed / Lapsed |