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US4963303A
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US
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Ultrafiltration polyimide membrane and its use for recovery of dewaxing aid
Assignee: ExxonMobil Technology and Engineering Co
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Filing: 1989-12-29
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Granted: 1990-10-16
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Expires: 2009-12-29
Abstract
Abstract Polyimide ultrafiltration membranes made using a single solvent and containing a pore forming agent have been produced and have been found to be useful for recovering dewaxing aid used in dewaxing process.
Inventors
- 👤 Bryce P. Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 02:00
CPC Classifications
B; B01; B01D; B01D61/00; B01D61/14; B01D61/145; B01D71/00; B01D71/06; B01D71/58; B01D71/62; B01D71/64; C; C10; C10G; C10G73/00; C10G73/02; C10G73/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
86 words
A method for producing a polyimide ultrafiltration membrane comprising the steps of dissolving a fully imidized polyimide polymer in a pro solvent and adding a pore forming agent characterized by having 43% more molar volume than the solvent used, a solubility parameter equal to or greater than that of the solvent and a polar end and substantial hydrocarbon character, to produce a casting solution, using said casting solution to produce a thin layer of said polyimide polymer/solvent/pore former, and quenching the layers in a quenching solvent.
Claim 2
Independent Claim
86 words
A method for producing a polyimide ultrafiltration membrane comprising the steps of dissolving a fully imidized polyimide polymer in a pro solvent and adding a pore forming agent characterized by having 43% more molar volume than the solvent used, a solubility parameter equal to or greater than that of the solvent and a polar end and substantial hydrocarbon character, to produce a casting solution, using said casting solution to produce a thin layer of said polyimide polymer/solvent/pore former, and quenching the layers in a quenching solvent.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein the polyimide polymer is based on 5(6)-amino-1-(4'-aminophenyl)-1,3,3-trimethylindane.
Claim 4
Dependent Claim
30 words
The method of claim 1 or 2 wherein the casting solution comprises 14-22 wt % polymer, about 6 to 20 wt % pore former and the balance is the solvent.
Claim 5
Dependent Claim
32 words
The method of claim 1 or 2 wherein the solvent used is selected from methylene chloride, ethylene chloride, chloroform, tetrachloroethane, acetophenone, cyclohexanone, m-cresol, dimethylformamide, N-methylpyrrolidone (NMP), or dimethylacetamide (DMAC) and mixtures thereof.
Claim 6
Dependent Claim
12 words
The method of claim 1 or 2 wherein the solvent is dimethylformamide.
Claim 7
Dependent Claim
12 words
The method of claim 5 wherein the pore former is epsilon caprolactam.
Claim 8
Dependent Claim
24 words
The method of claim 1 wherein the pore former is characterized by having at least about 50% more molar volume than the solvent used.
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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) | 1993-10-15 | 1994-04-16 | 1994-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-15 | 1998-04-16 | 1998-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-15 | 2002-04-16 | 2002-10-16 | $7700.00 | Window Closed / Lapsed |