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US4512894A
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Process for the production of semipermeable polybenzimidazole membranes and the resultant product
Assignee: Celanese Corp
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Filing: 1982-12-17
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Granted: 1985-04-23
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Expires: 2002-12-17
Abstract
Abstract A membrane cast in the form of either a hollow filament or a flat film formed of a polybenzimidazole polymer is subjected to an annealing process by contacting the membrane with a non-aqueous annealing medium comprised of a solvent for the polymer and a non-solvent for the polymer. Such an annealing step can advantageously occur at an annealing temperature below about 125° C. (e.g., below 100° C.) These polybenzimidazole membranes find particular utility in reverse osmosis desalination processes. The annealing step of the present invention improves the mechanical and separative properties of the membrane.
Inventors
- 👤 Donald G. J. Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:14
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/58; B01D71/62
Claims Analysis
Total Claims: 58
Claim 1
Independent Claim
106 words
In a process for the production of a semipermeable polybenzimidazole membrane wherein a film or hollow filament is formed from a solution of a polybenzimidazole polymer and subsequently subjected to an annealing step at elevated temperatures in the presence of an annealing medium, the improvement comprising conducting said annealing step in the presence of a non-aqueous annealing medium at a temperature below about 125° C. comprised of a solvent for said polymer and a non-solvent for said polymer whereby said membrane exhibits enhanced separative properties in contrast to a membrane having been annealed in an annealing medium which does not comprise a solvent for said polymer.
Claim 2
Dependent Claim
106 words
In a process for the production of a semipermeable polybenzimidazole membrane wherein a film or hollow filament is formed from a solution of a polybenzimidazole polymer and subsequently subjected to an annealing step at elevated temperatures in the presence of an annealing medium, the improvement comprising conducting said annealing step in the presence of a non-aqueous annealing medium at a temperature below about 125° C. comprised of a solvent for said polymer and a non-solvent for said polymer whereby said membrane exhibits enhanced separative properties in contrast to a membrane having been annealed in an annealing medium which does not comprise a solvent for said polymer.
Claim 3
Dependent Claim
90 words
The process of claim 1 wherein said polybenzimidazole polymer consists essentially of recurring units of the formula: ##STR4## wherein R is a tetravalent aromatic nucleus, with the nitrogen atoms forming the polybenzimidazole rings paired upon adjacent carbon atoms of said aromatic nucleus, and R' is selected from the group consisting of (1) an aromatic ring, (2) an alkylene group having from four to eight carbon atoms, and (3) a heterocyclic ring selected from the group consisting of (a) pyridine, (b) pyrazine, (c) furan, (d) quinoline, (e) thiophene, and (f) pyran.
Claim 4
Dependent Claim
11 words
The process of claim 1 wherein said polybenzimidazole polymer is poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole.
Claim 5
Dependent Claim
28 words
The process of claim 1 wherein said solvent capable of dissolving said polymer is selected from the group consisting of N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone.
Claim 6
Dependent Claim
11 words
The process of claim 1 wherein said solvent is N,N-dimethyl acetamide.
Claim 7
Dependent Claim
24 words
The process of claim 1 wherein said annealing step is conducted for a period of time ranging from about 30 seconds to 20 minutes.
Claim 8
Dependent Claim
25 words
The process of claim 1 wherein said non-solvent comprises a polyhydroxy aliphatic alcohol having two to three hydroxy groups and two to six carbon atoms.
Claim 9
Dependent Claim
11 words
The process of claim 1 wherein said non-solvent comprises ethylene glycol.
Claim 10
Dependent Claim
10 words
The process of claim 1 wherein said non-solvent comprises glycerol.
Claim 11
Dependent Claim
11 words
The process of claim 1 wherein said non-solvent comprises 1,3-butylene glycol.
Claim 12
Dependent Claim
18 words
The process of claim 1 wherein said. annealing step is conducted at a temperature below about 100° C.
Claim 13
Dependent Claim
15 words
The process of claim 1 wherein said non-solvent comprises a plasticizer for said polybenzimidazole polymer.
Claim 14
Dependent Claim
32 words
The process of claim 1 wherein said annealing medium comprises from about 1 to 50 percent by weight of said solvent and about 99 to 50 percent by weight of said non-solvent.
Claim 15
Dependent Claim
32 words
The process of claim 13 wherein said annealing medium comprises from about 1 to 30 percent by weight of said solvent and about 70 to 99 percent by weight of said non-solvent.
Claim 16
Dependent Claim
12 words
A semipermeable membrane produced in accordance with the process of claim 1.
Claim 17
Dependent Claim
140 words
A process for the production of a semi-permeable polybenzimidazole membrane comprising: (a) providing a solution of a polybenzimidazole polymer in a solvent capable of dissolving said polymer; (b) depositing a film of said solution upon a support; (c) removing an amount of solvent from said film sufficient to result in the formation of a solid layer on the exposed surface of said film having a density which exceeds that of the remaining portion of said film on which said solid layer of increased density is formed; (d) washing the resulting film with a non-solvent for said polymer to remove residual solvent thereby producing a semipermeable membrane; and (e) annealing the resulting semipermeable membrane while in contact with a non-aqueous annealing medium at a temperature below about 125° C. comprising a solvent for said polymer and a non-solvent for said polymer.
Claim 18
Dependent Claim
140 words
A process for the production of a semi-permeable polybenzimidazole membrane comprising: (a) providing a solution of a polybenzimidazole polymer in a solvent capable of dissolving said polymer; (b) depositing a film of said solution upon a support; (c) removing an amount of solvent from said film sufficient to result in the formation of a solid layer on the exposed surface of said film having a density which exceeds that of the remaining portion of said film on which said solid layer of increased density is formed; (d) washing the resulting film with a non-solvent for said polymer to remove residual solvent thereby producing a semipermeable membrane; and (e) annealing the resulting semipermeable membrane while in contact with a non-aqueous annealing medium at a temperature below about 125° C. comprising a solvent for said polymer and a non-solvent for said polymer.
Claim 19
Dependent Claim
90 words
The proces of claim 16 wherein said polybenzimidazole polymer consists essentially of recurring units of the formula: ##STR5## wherein R is a tetravalent aromatic nucleus, with the nitrogen atoms forming the benzimidazole rings paired upon adjacent carbon atoms of said aromatic nucleus, and R' is selected from the group consisting of (1) an aromatic ring, (2) an alkylene group having from four to eight carbon atoms, and (3) a heterocyclic ring selected from the group consisting of (a) pyridine, (b) pyrazine, (c) furan, (d) quinoline, (e) thiophene, and (f) pyran.
Claim 20
Dependent Claim
11 words
The process of claim 16 wherein said polybenzimidazole polymer is poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole.
Claim 21
Dependent Claim
26 words
The process of claim 16 wherein said solvent for said polymer is selected from the group consisting of N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone.
Claim 22
Dependent Claim
11 words
The process of claim 16 wherein said solvent is N,N-dimethyl acetamide.
Claim 23
Dependent Claim
36 words
The process of claim 19 wherein said polybenzimidazole polymer is present in said solvent in step (a) in a concentration of about 5 to 30 percent by weight based upon the total weight of the solution.
Claim 24
Dependent Claim
22 words
The process of claim 16 wherein said film is deposited on said support in a thickness of about 1 to 30 mils.
Claim 25
Dependent Claim
25 words
The process of claim 16 wherein said film is washed with water in step (d) to remove residual solvent and thereby produce a semipermeable membrane.
Claim 26
Dependent Claim
22 words
The process of claim 23 wherein said water is employed in step (d) at a temperature of about 5 to 30° C.
Claim 27
Dependent Claim
24 words
The process of claim 16 wherein said annealing step is conducted for a period of time ranging from about 30 seconds to 20 minutes.
Claim 28
Dependent Claim
25 words
The process of claim 16 wherein said non-solvent comprises a polyhydroxy aliphatic alcohol having two to three hydroxy groups and two to six carbon atoms.
Claim 29
Dependent Claim
11 words
The proces of claim 16 wherein said non-solvent comprises ethylene glycol.
Claim 30
Dependent Claim
10 words
The process of claim 16 wherein said non-solvent comprises glycerol.
Claim 31
Dependent Claim
11 words
The process of claim 16 wherein said non-solvent comprises 1,3-butylene glycol.
Claim 32
Dependent Claim
18 words
The process of claim 16 wherein said annealing step is conducted at a temperature below about 100° C.
Claim 33
Dependent Claim
21 words
The process of claim 16 wherein said annealing step is conducted under conditions wherein said semipermeable membrane is free to shrink.
Claim 34
Dependent Claim
15 words
The process of claim 16 wherein said non-solvent comprises a plasticizer for said polybenzimidazole polymer.
Claim 35
Dependent Claim
33 words
The process of claim 16 wherein said annealing medium comprises from about 1 to 50 percent by weight of said solvent and from about 99 to 50 percent by weight of said non-solvent.
Claim 36
Dependent Claim
33 words
The process of claim 33 wherein said annealing medium comprises from about 1 to 30 percent by weight of said solvent and from about 70 to 99 percent by weight of said non-solvent.
Claim 37
Dependent Claim
12 words
A semipermeable membrane produced in accordance with the process of claim 16.
Claim 38
Dependent Claim
160 words
A process for the production of a semi-permeable polybenzimidazole membrane in the form of a hollow filament comprising: (a) providing a solution of a polybenzimidazole polymer in a solvent capable of dissolving said polymer; (b) extruding at least one hollow filament through a concentric jet spinnerette from said solution; (c) coagulating the thus-formed filament in a coagulation bath; (d) removing an amount of solvent from said filament sufficient to result in the formation of a solid layer on the exposed surface of said filament having a density which exceeds that of the remaining portion of said filament on which said solid layer of increased density is formed; (e) washing the filament with a non-solvent for said polymer to remove residual solvent thereby producing a semipermeable membrane in the form of a hollow filament; and (f) annealing the resulting membrane while in contact with a non-aqueous annealing medium comprised of a solvent for said polymer and a non-solvent for said polymer.
Claim 39
Dependent Claim
160 words
A process for the production of a semi-permeable polybenzimidazole membrane in the form of a hollow filament comprising: (a) providing a solution of a polybenzimidazole polymer in a solvent capable of dissolving said polymer; (b) extruding at least one hollow filament through a concentric jet spinnerette from said solution; (c) coagulating the thus-formed filament in a coagulation bath; (d) removing an amount of solvent from said filament sufficient to result in the formation of a solid layer on the exposed surface of said filament having a density which exceeds that of the remaining portion of said filament on which said solid layer of increased density is formed; (e) washing the filament with a non-solvent for said polymer to remove residual solvent thereby producing a semipermeable membrane in the form of a hollow filament; and (f) annealing the resulting membrane while in contact with a non-aqueous annealing medium comprised of a solvent for said polymer and a non-solvent for said polymer.
Claim 40
Dependent Claim
90 words
The process of claim 36 wherein said polybenzimidazole polymer consists essentially of recurring units of the formula: ##STR6## wherein R is a tetravalent aromatic nucleus, with the nitrogen atoms forming the benzimidazole rings paired upon adjacent carbon atoms of said aromatic nucleus, and R' is selected from the group consisting of (1) an aromatic ring, (2) an alkylene group having from four to eight carbon atoms, and (3) a heterocyclic ring selected from the group consisting of (a) pyridine, (b) pyrazine, (c) furan, (d) quinoline, (e) thiophene, and (f) pyran.
Claim 41
Dependent Claim
11 words
The process of claim 36 wherein said polybenzimidazole polymer is poly-2,2'(m-phenylene)-5,5'-bibenzimidazole.
Claim 42
Dependent Claim
28 words
The process of claim 36 wherein said solvent capable of dissolving said polymer is selected from the group consisting of N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone.
Claim 43
Dependent Claim
11 words
The process of claim 39 wherein said solvent is N,N-dimethyl acetamide.
Claim 44
Dependent Claim
36 words
The process of claim 39 wherein said polybenzimidazole polymer is present in said solvent in step (a) in a concentration of about 5 to 30 percent by weight based upon the total weight of the solution.
Claim 45
Dependent Claim
22 words
The process of claim 36 wherein said film is deposited on said support in a thickness of about 1 to 30 mils.
Claim 46
Dependent Claim
26 words
The process of claim 36 wherein said resulting film is washed with water in step (e) to remove residual solvent and thereby produce a semipermeable membrane.
Claim 47
Dependent Claim
22 words
The process of claim 43 wherein said water is employed in step (e) at a temperature of about 5 to 30° C.
Claim 48
Dependent Claim
24 words
The process of claim 36 wherein said annealing step is conducted for a period of time ranging from about 30 seconds to 20 minutes.
Claim 49
Dependent Claim
25 words
The process of claim 36 wherein said non-solvent comprises a polyhydroxy aliphatic alcohol having two to three hydroxy groups and two to six carbon atoms.
Claim 50
Dependent Claim
11 words
The process of claim 36 wherein said non-solvent comprises ethylene glycol.
Claim 51
Dependent Claim
10 words
The process of claim 36 wherein said non-solvent comprises glycerol.
Claim 52
Dependent Claim
11 words
The process of claim 36 wherein said non-solvent comprises 1,3-butylene glycol.
Claim 53
Dependent Claim
18 words
The process of claim 36 wherein said annealing step is conducted at a temperature below about 125° C.
Claim 54
Dependent Claim
21 words
The process of claim 36 wherein said annealing step is conducted under conditions wherein said semipermeable membrane is free to shrink.
Claim 55
Dependent Claim
15 words
The process of claim 36 wherein said non-solvent comprises a plasticizer for said polybenzimidazole polymer.
Claim 56
Dependent Claim
33 words
The process of claim 36 wherein said annealing medium comprises from about 1 to 50 percent by weight of said solvent and from about 99 to 50 percent by weight of said non-solvent.
Claim 57
Dependent Claim
32 words
The process of claim 53 wherein said annealing medium comprises from about 1 to 30 percent by weight of said solvent and about 70 to 99 percent by weight of said non-solvent.
Claim 58
Dependent Claim
12 words
A semipermeable membrane produced in accordance with the process of claim 36.
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) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |