US4784880A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for modifying asymmetric membranes by endo-treating
Assignee: Albany International Corp
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Filing: 1986-07-25
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Granted: 1988-11-15
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Expires: 2006-07-25
Abstract
Abstract A method of upgrading the selectively of a dry asymmetric permselective membrane comprising a porous barrier layer adjacent to a porous main body, where the barrier layer has an external obverse surface. The method comprises maintaining the barrier layer surface in a drying atmosphere while applying a wetting liquid which is not a solvent for the bulk of the membrane to the obverse surface to wet interstices of the bulk of the membrane, and drying the membrane by continuing the exposure of the external surface of the barrier layer to the drying atmosphere as the wetting liquid moves from the obverse surface through the membrane main body and the barrier layer.
Inventors
- 👤 Myron J. Coplan
- 👤 R. Douglas Burchesky
- 👤 Salvatore Giglia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 01:45
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0081; B01D67/0088; B01D53/00; B01D53/22; B01D53/228; B01D67/0083; B01D67/0093; B01D69/00; B01D69/02; B01D2325/00; B01D2325/02; B01D2325/022
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
106 words
The method of upgrading the selectivity of a dry asymmetric permselective membrane comprising a porous barrier layer adjacent to a porous main body, the barrier layer having an external surface and the main body having an external obverse surface, comprising: (a) a wetting liquid which is not a solvent for the bulk of the membrane to said obverse surface to wet interstices of the bulk of the membrane; and (b) drying the membrane by continuing the exposure of the external surface of the barrier layer to a drying atmosphere, the wetting liquid moving from said obverse surface through the membrane main body and the barrier layer.
Claim 2
Independent Claim
106 words
The method of upgrading the selectivity of a dry asymmetric permselective membrane comprising a porous barrier layer adjacent to a porous main body, the barrier layer having an external surface and the main body having an external obverse surface, comprising: (a) a wetting liquid which is not a solvent for the bulk of the membrane to said obverse surface to wet interstices of the bulk of the membrane; and (b) drying the membrane by continuing the exposure of the external surface of the barrier layer to a drying atmosphere, the wetting liquid moving from said obverse surface through the membrane main body and the barrier layer.
Claim 3
Dependent Claim
17 words
The process of claim 1 in which the wetting liquid comprises a dilute solution of a polymer.
Claim 4
Dependent Claim
25 words
The process of claim 1 in which the wetting liquid has the capability to dissolve a minor fraction of the material comprising the asymmetric membrane.
Claim 5
Dependent Claim
43 words
The process of claim 1 in which the wetting liquid consists of two or more miscible liquids in such proportions that the more volatile components are in the majority and the less volatile components have a mild plasticizing action on the barrier layer.
Claim 6
Dependent Claim
19 words
The process of claim 1 in which the wetting liquid comprises a highly diluted suspension of colloidally dispersed species.
Claim 7
Dependent Claim
19 words
The process of claim 1 in which the wetting liquid comprises a dilute solution of high molecular weight dye.
Claim 8
Dependent Claim
18 words
The process of claim 1 in which the wetting liquid comprises a dilute solution of an inorganic salt.
Claim 9
Dependent Claim
29 words
The process of claim 1 in which the wetting liquid comprises a dilute solution of a reactive agent capable of chemically modifying the parent substance of the asymmetric membrane.
Claim 10
Dependent Claim
15 words
The process of claim 1 in which the dry asymmetric membrane is inorganic in nature.
Claim 11
Dependent Claim
23 words
The process of claim 2 in which the membrane is comprised of a polymer different from the polymer dissolved in the wetting solution.
Claim 12
Dependent Claim
27 words
The process of claim 3 in which the asymmetric membrane comprises a mixture of substances selected to provide a fraction which is soluble in the wetting liquid.
Claim 13
Dependent Claim
18 words
The process of claim 9 in which the wetting liquid is a dilute sol of an inorganic oxide.
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) | 1991-11-15 | 1992-05-16 | 1992-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-15 | 1996-05-16 | 1996-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-15 | 2000-05-16 | 2000-11-15 | $7700.00 | Window Closed / Lapsed |