US4673418A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing an integral, asymmetric membrane and the resultant membrane
Assignee: GKSS Forshungszentrum Geesthacht GmbH
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Filing: 1985-05-31
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Granted: 1987-06-16
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Expires: 2005-05-31
Abstract
Abstract A method for producing integral, asymmetric membranes for separating mixtures of gases is disclosed. A membrane forming polymer, a solvent for the polymer, and a swelling agent are mixed to form a pourable liquid mixture; the solvent has a lower boiling point than the other components in the mixture, the polymer is not soluble in the swelling agent, and the swelling agent does not react with the polymer or the solvent. The liquid mixture is spread to form a thin film, the film is exposed to air or an inert gas to form a surface skin by evaporation and is thereafter contacted with a precipitation agent. A preferred integral, asymmetric membrane is produced when the membrane forming polymer is a polyetherimide, the solvent is a halogenated hydrocarbon and the swelling agent is one or more compound selected from the group consisting of an alkyl substituted benzene, an aliphatic carboxylic acid, and a chlorinated hydrocarbon.
Inventors
- 👤 Klaus-Viktor Peinemann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:53
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/58; B01D71/62; B01D71/64; B01D71/643; B01D69/00; B01D69/12
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
188 words
A method for producing integral, asymetrical membranes for separating gases in mixtures comprising: mixing together a polyether imide membrane forming polymer which forms membranes that are permeable to at least one gas in a mixture of gases, a volatile solvent for the polymer having a lower boiling point than any other component in the mixture, and an organic liquid swelling agent in which the polymer is not soluble and which does not react with either the polymer or the solvent to form a pourable liquid mixture, pore-free membranes that are permeable to at least one gas in the mixture of gases, the solvent is selected to have a lower boiling point than the other components in the mixture, and the swelling agent is selected to be an organic liquid in which the polymer is not soluble and which does not react with the polymer or the solvent; spreading said liquid mixture to form a thin film; exposing said film to air or an inert gas to form a surface skin by evaporation, and contacting said film with a precipitation agent to form an integral, asymmetric polyether imide membrane.
Claim 2
Independent Claim
188 words
A method for producing integral, asymetrical membranes for separating gases in mixtures comprising: mixing together a polyether imide membrane forming polymer which forms membranes that are permeable to at least one gas in a mixture of gases, a volatile solvent for the polymer having a lower boiling point than any other component in the mixture, and an organic liquid swelling agent in which the polymer is not soluble and which does not react with either the polymer or the solvent to form a pourable liquid mixture, pore-free membranes that are permeable to at least one gas in the mixture of gases, the solvent is selected to have a lower boiling point than the other components in the mixture, and the swelling agent is selected to be an organic liquid in which the polymer is not soluble and which does not react with the polymer or the solvent; spreading said liquid mixture to form a thin film; exposing said film to air or an inert gas to form a surface skin by evaporation, and contacting said film with a precipitation agent to form an integral, asymmetric polyether imide membrane.
Claim 3
Dependent Claim
39 words
The method of claim 1, wherein the film is contacted with a precipitation agent consisting of an organic liquid in which the polymer is not soluble and is thereafter dried in the presence of air or an inert gas.
Claim 4
Dependent Claim
17 words
The method of claim 1, wherein the surface skin of the membrane is covered with an elastomer.
Claim 5
Dependent Claim
31 words
The method of claim 1, wherein the solvent and swelling agent are miscible, and the solvent is present in an amount sufficient to completely dissolve the polymer and the swelling agent.
Claim 6
Dependent Claim
46 words
The method of claim 1, wherein the membrane forming polymer is a polyetherimide, the solvent is a halogenated hydrocarbon and the swelling agent is one or more compound selected from the group consisting of an alkyl substituted benzene, an aliphatic carboxylic acid, and a chlorinated hydrocarbon.
Claim 7
Dependent Claim
13 words
The method of claim 1, wherein the membrane has an open cell substructure.
Claim 8
Dependent Claim
10 words
The method of claim 3, wherein the elastomer is silicone.
Claim 9
Dependent Claim
25 words
The method of claim 5, wherein the halogenated hydrocarbon solvent is one or more compound selected from the group consisting of dichloromethane, 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane.
Claim 10
Dependent Claim
28 words
The method of claim 5, wherein the swelling agent is one or more compound selected from the group consisting of formic acid, acetic acid, toluene, xylene and trichloroethylene.
Claim 11
Dependent Claim
24 words
The method of claim 9, wherein the concentration of the swelling agent in the pourable liquid mixture is between 5 and 40 weight percent.
Claim 12
Dependent Claim
11 words
The method of claim 5, wherein the precipitation agent is acetone.
Claim 13
Dependent Claim
10 words
A membrane produced according to the method of claim 1.
Claim 14
Dependent Claim
21 words
The membrane of claim 12, produced in the form of a plate, a tube, a coil module or a hollow fiber.
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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) | 1990-06-15 | 1990-12-15 | 1991-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-15 | 1994-12-15 | 1995-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-15 | 1998-12-15 | 1999-06-16 | $7700.00 | Window Closed / Lapsed |