US3841492A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of semipermeable polybenzimidazole membranes
Assignee: Celanese Corp
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Filing: 1973-06-29
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Granted: 1974-10-15
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Expires: 1993-06-29
Abstract
Abstract A process is provided for forming an improved reverse osmosis membrane of unusually high physical durability and chemical stability. The membrane is formed of the specific polybenzimidazole chemical structure indicated in the claims. In a preferred embodiment the membrane is formed of poly-2,2''-(mphenylene)-5,5''-bibenzimidazole. The membrane is formed by (a) providing a solution of the polybenzimidazole polymer of the formula indicated, (b) depositing a film of the solution upon a support, (c) evaporating an amount of solvent from the film sufficient to allow the formation of a thin solid layer on the exposed surface of the film having a density which is substantially greater than that of the remaining portion of the film on which the solid layer of increased density is formed, and (d) washing the resulting film with a non-solvent for the polymer to remove residual solvent. The reverse osmosis membranes exhibit performance characteristics which are more highly resistant to deterioration upon the passage of time, are capable of operation at high pressures (e.g., 1,000 psi and up), are capable of operation at elevated temperatures (e.g., 100*C), and exhibit outstanding chemical stability.
Inventors
- 👤 W Brinegar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:29
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/58; B01D71/62; C; C08; C08G; C08G73/00; C08G73/06; C08G73/18
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
34 words
A PROCESS FOR PRODUCING AN IMPROVED REVERSE OSMOSIS MEMBRANE OF UNUSUALLY HIGH PHYSICAL DURABILITY AND CHEMICAL STABILITY COMPRISING: A. PROVIDING A SOLUTION OF A POLYBENZIMIDAZOLE POLYMER CONSISTING ESSENTIALLY OF RECURRING UNITS OF THE FORMULA
Claim 2
Dependent Claim
34 words
A PROCESS FOR PRODUCING AN IMPROVED REVERSE OSMOSIS MEMBRANE OF UNUSUALLY HIGH PHYSICAL DURABILITY AND CHEMICAL STABILITY COMPRISING: A. PROVIDING A SOLUTION OF A POLYBENZIMIDAZOLE POLYMER CONSISTING ESSENTIALLY OF RECURRING UNITS OF THE FORMULA
Claim 3
Dependent Claim
12 words
A process according to claim 1 wherein said polybenzimidazole polymer is poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole.
Claim 4
Dependent Claim
29 words
A process according to 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 5
Dependent Claim
12 words
A process according to claim 1 wherein said solvent is N,N-dimethyl acetamide.
Claim 6
Dependent Claim
34 words
A process according to claim 4 wherein said polybenzimidazole polymer is present in said solvent in a concentration of about 5 to 30 percent by weight based upon the total weight of the solution.
Claim 7
Dependent Claim
23 words
A process according to claim 1 wherein said film is deposited on said support in a thickness of about 1 to 30 mils.
Claim 8
Dependent Claim
33 words
A process according to claim 1 wherein said thin solid layer formed upon the surface of said film by the evaporation of said solvent has a thickness of about 0.01 to 20 microns.
Claim 9
Dependent Claim
25 words
A process according to claim 1 wherein said resulting film is washed in water to remove residual solvent and thereby produce a reverse osmosis Membrane.
Claim 10
Dependent Claim
19 words
A process according to claim 8 wherein said water is present at a temperature of about 5* to 30*C.
Claim 11
Dependent Claim
33 words
A process for producing an improved reverse osmosis membrane of unusually high physical durability and chemical stability comprising: a. providing a solution of polybenzimidazole polymer consisting essentially of recurring units of the formula:
Claim 12
Dependent Claim
33 words
A process for producing an improved reverse osmosis membrane of unusually high physical durability and chemical stability comprising: a. providing a solution of polybenzimidazole polymer consisting essentially of recurring units of the formula:
Claim 13
Dependent Claim
12 words
A process according to claim 10 wherein said polybenzimidazole polymer is poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole.
Claim 14
Dependent Claim
12 words
A process according to claim 10 wherein said solvent is N,N-dimethyl acetamide.
Claim 15
Dependent Claim
22 words
A process according to claim 10 wherein said resulting film is washed with water having a temperature of about 5* to 30*C.
Claim 16
Dependent Claim
171 words
A process for producing an improved reverse osmosis membrane of unusually high physical durability and chemical stability suitable for use in a desalination separation comprising: a. providing a solution of poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole in N,N-dimethyl acetamide wherein said polymer is present in a concentration of about 10 to 20 percent by weight based upon the total weight of said solution, b. depositing a film of said solution upon a support in a thickness of about 2 to 10 mils, c. evaporating an amount of said N,N-dimethyl acetamide from said film sufficient to allow the formation of a thin solid layer having a thickness of about 0.1 to 5 microns on the exposed surface of said film having a density which is substantially greater than that of the remaining portion of said film on which said solid layer of increased density is formed, and d. washing the resulting film with water having a temperature of about 5* to 30*C. to remove residual solvent thereby producing a semipermeable membrane suitable for a reverse osmosis separation.
Claim 17
Dependent Claim
171 words
A process for producing an improved reverse osmosis membrane of unusually high physical durability and chemical stability suitable for use in a desalination separation comprising: a. providing a solution of poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole in N,N-dimethyl acetamide wherein said polymer is present in a concentration of about 10 to 20 percent by weight based upon the total weight of said solution, b. depositing a film of said solution upon a support in a thickness of about 2 to 10 mils, c. evaporating an amount of said N,N-dimethyl acetamide from said film sufficient to allow the formation of a thin solid layer having a thickness of about 0.1 to 5 microns on the exposed surface of said film having a density which is substantially greater than that of the remaining portion of said film on which said solid layer of increased density is formed, and d. washing the resulting film with water having a temperature of about 5* to 30*C. to remove residual solvent thereby producing a semipermeable membrane suitable for a reverse osmosis separation.
Claim 18
Dependent Claim
22 words
An improved reverse osmosis polybenzimidazole membrane of unusually high physical durability and chemical stability consisting essentially of recurring units of the formula:
Claim 19
Dependent Claim
22 words
An improved reverse osmosis polybenzimidazole membrane of unusually high physical durability and chemical stability consisting essentially of recurring units of the formula:
Claim 20
Dependent Claim
14 words
An improved reverse osmosis membrane in accordance with claim 15 consisting essentially of poly-2,2''-(m-phenylene)-5,5''-benzimidazole.
Claim 21
Dependent Claim
17 words
An improved reverse osmosis membrane in accordance with claim 15 wherein said membrane is a flat film.
Claim 22
Dependent Claim
17 words
An improved reverse osmosis membrane in accordance with claim 15 wherein said membrane is a hollow filament.
Claim 23
Dependent Claim
33 words
An improved reverse osmosis membrane in accordance with claim 18 wherein said filament has an outer diameter of about 25 to 1,000 microns, and an inner diameter of about 12 to 500 microns.
Claim 24
Dependent Claim
40 words
An improved reverse osmosis membrane of unusually high physical durability and chemical stability in the form of a flat film consisting essentially of poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole having an inherent viscosity in 97 percent sulfuric acid at 25*C. of at least about 0.4.
Claim 25
Dependent Claim
40 words
An improved reverse osmosis membrane of unusually high physical durability and chemical stability in the form of a flat film consisting essentially of poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole having an inherent viscosity in 97 percent sulfuric acid at 25*C. of at least about 0.4.
Claim 26
Dependent Claim
56 words
An improved reverse osmosis membrane of unusually high physical durability and chemical stability in the form of a hollow filament consisting essentially of poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole having an inherent viscosity in 97 percent sulfuric acid of at least about 0.5, an outer diameter of about 25 to 1,000 microns, and an inner diameter of about 12 to 500.
Claim 27
Dependent Claim
56 words
An improved reverse osmosis membrane of unusually high physical durability and chemical stability in the form of a hollow filament consisting essentially of poly-2,2''-(m-phenylene)-5,5''-bibenzimidazole having an inherent viscosity in 97 percent sulfuric acid of at least about 0.5, an outer diameter of about 25 to 1,000 microns, and an inner diameter of about 12 to 500.
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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) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |