US4604204A
Expired / Lapsed
US
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Porous, semipermeable membranes of chemically modified cellulose acetate
Assignee: Aligena AG
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Filing: 1983-11-23
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Granted: 1986-08-05
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Expires: 2003-11-23
Abstract
Abstract Cellulose acetate containing membranes which have pore diameters of about 10 to 1000 Å are modified by reacting these membranes (a) with (b) an at least difunctional compound, e.g. cyanuric chloride, (c) a polyfunctional oligomer or polymer, e.g. polyethyleneimine, and then with (d) a compound which contains at least one ionic group and one group capable of reaction with component (c). Reactant (d) is necessary only if the polyfunctional component (c) does not already contain sufficient ionic groups. The novel membranes are suitable for ultrafiltration and can be used for example for separating monovalent ions of low ionic weight from polyvalent ions of low or relatively high ionic weight of from monovalent ions of relatively high ionic weight and for separating ionic compounds (salts) from non-ionic (organic) compounds or from ionic compounds which have a different molecular weight or opposite charge. They can be used for example for separating salts from organic compounds (dyes) or in waste-water treatment.
Inventors
- 👤 Charles Linder
- 👤 Mordechai Perry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:52
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/08; B01D71/12; B01D71/14; B01D71/16
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
240 words
A porous, modified cellulose acetate membrane having a structure suitable for ultrafiltration and reverse osmosis, said membrane being prepared by a sequence of chemical reactions consisting essentially of steps (1) to (3), wherein: step (1) is reacting (a) a cellulose acetate containing membrane having a pore diameter in the range of from 10 to 1000 Å, with (b) an organic compound which contains at least one group (b 1 ) capable of reaction with hydroxyl groups of the membrane (a), and at least one group (b 2 ) capable of reaction with component (c), to bond the hydroxyl groups to a group (b 1 ), such that a membrane obtained from step (1) has at least one reactive group (b 2 ), step (2) is reacting group (b 2 ) of said membrane with (c) a polyfunctional linear or branched polymer containing functional groups (c 1 ) and (c 2 ), to bond group (b 2 ) to group (c 1 ), and thereby introduce said polymer into said membrane, and step (3) is reacting (d) a compound which contains at least one ionic group and at least one group (d 1 ) capable of reaction with group (c 2 ), provided that said polyfunctional linear or branched polymer (c) itself does not already possess sufficient ionic groups, to bond group (d 1 ) to group (c 2 ) to form a membrane containing said at least one ionic group.
Claim 2
Dependent Claim
240 words
A porous, modified cellulose acetate membrane having a structure suitable for ultrafiltration and reverse osmosis, said membrane being prepared by a sequence of chemical reactions consisting essentially of steps (1) to (3), wherein: step (1) is reacting (a) a cellulose acetate containing membrane having a pore diameter in the range of from 10 to 1000 Å, with (b) an organic compound which contains at least one group (b 1 ) capable of reaction with hydroxyl groups of the membrane (a), and at least one group (b 2 ) capable of reaction with component (c), to bond the hydroxyl groups to a group (b 1 ), such that a membrane obtained from step (1) has at least one reactive group (b 2 ), step (2) is reacting group (b 2 ) of said membrane with (c) a polyfunctional linear or branched polymer containing functional groups (c 1 ) and (c 2 ), to bond group (b 2 ) to group (c 1 ), and thereby introduce said polymer into said membrane, and step (3) is reacting (d) a compound which contains at least one ionic group and at least one group (d 1 ) capable of reaction with group (c 2 ), provided that said polyfunctional linear or branched polymer (c) itself does not already possess sufficient ionic groups, to bond group (d 1 ) to group (c 2 ) to form a membrane containing said at least one ionic group.
Claim 3
Dependent Claim
48 words
A membrane according to claim 1, wherein said organic compound (b) is cyanuric chloride, said polymer (c) is polyethylene imine and said compound (d) is a reactive azo dyestuff containing sulphonic acid or carboxyl groups and as reactive groups monochlorotriazinyl, dichlorotrazinyl, 2,4-dichloropyrimidinyl, vinylsulphonyl, β-sulfatoethylsulfonyl, β-chloroethylsulfonyl or β-sulfatoethylaminosulfonyl radicals.
Claim 4
Dependent Claim
20 words
A membrane according to claim 1, wherein the pore diameter of the membrane (a) is 10 to 500 521 .
Claim 5
Dependent Claim
19 words
A membrane according to claim 3, wherein the pore diameter of the membrane (a) is 10 to 200 Å.
Claim 6
Dependent Claim
23 words
A membrane according to claim 1, wherein the acetate content of the cellulose acetate membrane (a) is 36 to 41 percent by weight.
Claim 7
Dependent Claim
15 words
A membrane according to claim 5, wherein the membrane (a) is made of cellulose 21/2-acetate.
Claim 8
Dependent Claim
25 words
A membrane according to claim 1, wherein said organic compound (b) is a cyclic carbonic acid imide halide, or an isocyanate, isothiocyanate or N-methylol compound.
Claim 9
Dependent Claim
24 words
A membrane according to claim 7, wherein said organic compound (b) is a halogeno-diazine or -triazine compound which contains at least 2 reactive substituents.
Claim 10
Dependent Claim
16 words
A membrane according to claim 8, wherein said organic compound (b) is cyanuric chloride or tetrachloropyrimidine.
Claim 11
Dependent Claim
21 words
A membrane according to claim 1, wherein said polymer (c) contains aliphatic or aromatic amino groups, hydroxyl groups or thiol groups.
Claim 12
Dependent Claim
20 words
A membrane according to claim 10, wherein said polymer (c) comprises polyethyleneimines, polyvinyl alcohols, polyvinylamines, vinylamine/vinyl sulfonate copolymers or polyvinylanilines.
Claim 13
Dependent Claim
30 words
A membrane according to claim 1, wherein said compound (d) is a colorless or colored compound which contains sulfonic acid groups, carboxylic acid groups or ammonium groups as ionic groups.
Claim 14
Dependent Claim
25 words
A membrane according to claim 1, wherein said compound (d) is a reactive azo dye containing sulfonic acid groups, carboxylic acid groups or ammonium groups.
Claim 15
Dependent Claim
34 words
A membrane according to claim 13, wherein said compound (d) is a reactive azo dyestuff containing sulphonic acid or carboxyl groups and as reactive groups monochlorotriazinyl, dichlorotriazinyl, 2,4-dichloropyrimidinyl, vinylfulphonyl, β-sulfatoethylsulfonyl, β-chloroethylsulfonyl or β-sulfatoethylaminosulfonyl radicals.
Claim 16
Dependent Claim
22 words
A membrane according to claim 1, wherein said organic compound (b) is cyanuric chloride and said polymer (c) is a vinylamine/vinylsulphonate copolymer.
Claim 17
Dependent Claim
35 words
A composite semipermeable membrane for ultrafiltration and reverse osmosis which comprises a microporous support and a superficially thin film having semipermeable properties, said film being a chemically modified cellulose acetate membrane according to claim 1.
Claim 18
Dependent Claim
19 words
A membrane according to claim 16, wherein the microporous support is of polyolefis, polyacrylonitriles, polyamides, polysulfones or cellulosic material.
Claim 19
Dependent Claim
13 words
A membrane according to claim 17, wherein the microporous support is of polypropylene.
Claim 20
Dependent Claim
19 words
A membrane according to claim 16, wherein the semipermeable film has a thickness of at least about 0.5 micron.
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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) | 1989-08-04 | 1990-02-03 | 1990-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-04 | 1994-02-03 | 1994-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-04 | 1998-02-03 | 1998-08-05 | $7700.00 | Window Closed / Lapsed |