US3837900A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semi-permeable membrane
Assignee: KORATEC Inc
•
Filing: 1973-01-22
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Granted: 1974-09-24
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Expires: 1993-01-22
Abstract
Abstract A treated cellulosic reverse osmosis membrane having decreased compaction and better resistance to flux rate decrease with time as compared with an untreated membrane. An untreated membrane is contacted with cross-linking resins such as methylolated melamines and subjected to microwave radiation.
Inventors
- 👤 R Englert
- 👤 L Berriman
- 👤 J Rendall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:14
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0081; B01D67/0093; B01D71/00; B01D71/06; B01D71/08; B01D71/12; B01D2323/00; B01D2323/30
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
30 words
The process of claim 1, wherein the combined membrane is insulated to prevent loss of heat generated within said membrane during curing while permitting vapor to escape from said membrane.
Claim 2
Dependent Claim
37 words
The process of claim 1, wherein the combined membrane is held at a temperature on the order of the curing temperature of the cross-linking agent during a time when the combined membrane is subjected to microwave radiation.
Claim 3
Dependent Claim
21 words
The process of claim 1, wherein the combined membrane is continually moved while the microwave radiation is applied to the membrane.
Claim 4
Dependent Claim
16 words
The method of claim 3, wherein the temperature is held between about 140* to about 500*F.
Claim 5
Dependent Claim
14 words
The process of claim 1, wherein the cross-linking agent is a urea-type formaldehyde reactant.
Claim 6
Dependent Claim
14 words
The process of claim 1, wherein the chemical blocking agent is a monomethylolated amide.
Claim 7
Dependent Claim
34 words
The process of claim 1 in which said blocking agent is chemically reactive with said cellulosic membrane and is selected from the group consisting of monomethylolated amides, monomethylolated ureas, cyclic ureas and methylolated melamines.
Claim 8
Dependent Claim
34 words
The process of claim 8 in which the treatment medium comprises about 0.5 to about 10.0 weight percent, based on the total weight of solids in the treatment medium, of said chemical blocking agent.
Claim 9
Dependent Claim
32 words
The process of claim 6 in which said crosslinking agent comprises about 0.5 to about 10.0 weight percent of the treatment medium, based on the total weight of solids in such medium.
Claim 10
Dependent Claim
38 words
The process of claim 9 in which the crosslinking agent is a urea-type formaldehyde reactant and comprises about 0.5 to about 10.0 weight percent of the treatment medium, based on the total weight of solids in such medium.
Claim 11
Dependent Claim
39 words
The process of claim 11 in which the semi-permeable membrane is combined with said crosslinking agent, catalyst and chemical blocking agent by impregnation with a solution of such components having a pH of from about 3.8 to about 4.2.
Claim 12
Dependent Claim
98 words
A process for decreasing the compaction of cellulosic semi-permeable membranes comprising combining an untreated membrane with a urea-type formaldehyde cross-linking agent, a catalyst and a chemical blocking agent selected from the group consisting of monomethylolated amides, monomethylolated ureas and cyclic ureas; placing the combined membrane in an environment which prevents any substantial loss of heat generated within said membrane which at the same time permits the escape of water vapor from the contacted membrane; and subjecting the resulting combined membrane to microwave radiation sufficient to result in a substantial reaction between the cross-linking agent and the cellulosic membrane.
Claim 13
Dependent Claim
18 words
The process of claim 13, wherein said environment is an oven heated from about 140* to about 500*F.
Claim 14
Dependent Claim
27 words
The process of claim 14 wherein said environment is a heat insulator placed over said membrane which insulator permits the escape of water vapor from said membrane.
Claim 15
Dependent Claim
83 words
A process for reducing flux rate loss in a cellulosic semi-permeable membrane comprising blocking the polymer molecules of said membrane with a chemical blocking agent to prevent a substantial coming together of said molecules during curing, contacting said membrane with a resin system containing a crosslinking agent capable of reacting with cellulose, and subjecting the resulting contacted membrane to microwave energy at a frequency of at least about 900 megacycleS per second over an interval of from about ten to about 300 seconds.
Claim 16
Dependent Claim
14 words
The process of claim 16 wherein the cross-linking agent is a urea-type formaldehyde reactant.
Claim 17
Dependent Claim
14 words
The process of claim 16 wherein the chemical blocking agent is a monomethylolated amide.
Claim 18
Dependent Claim
13 words
The process of claim 16 wherein the chemical blocking agent is metholated melamine.
Claim 19
Dependent Claim
13 words
The process of claim 17 wherein said cross-linking system contains an acid catalyst.
Claim 20
Dependent Claim
26 words
The process of claim 20 wherein said acid catalyst is added to said contacted membrane by soaking said contacted membrane in a solution containing said catalyst.
Claim 21
Dependent Claim
12 words
The process of claim 21 wherein said acid catalyst is zinc nitrate.
Claim 22
Dependent Claim
12 words
The process of claim 20 wherein said acid catalyst is hydrochloric acid.
Claim 23
Dependent Claim
13 words
The process of claim 20 wherein said acid catalyst is an organic catalyst.
Claim 24
Dependent Claim
12 words
The process of claim 24, wherein said acid catalyst is citric acid.
Claim 25
Dependent Claim
15 words
A cellulosic semi-permeable membrane of improved compaction resistance produced by the method of claim 1.
Claim 26
Dependent Claim
46 words
A process for decreasing compaction and reducing flux rate loss in cellulosic semi-permeable membranes comprising impregnating a cellulosic membrane with a resin system containing a chemical blocking agent and a crosslinking agent capable of reacting with cellulose, and thereafter subjecting the impregnated membrane to microwave radiation.
Claim 27
Dependent Claim
61 words
The process of claim 27 in which the treatment medium is at a pH of from about 3.8 to about 4.2 and comprises from about 0.5 to about 10.0 weight per cent of said chemical blocking agent and about 0.5 to about 10.0 weight per cent of said crosslinking agent, based on the total weight of solids in the treatment medium.
References Cited (Backward Citations)
US2689806A
Cited
US3428584A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |