US4541972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of cellulose acetate membrane and its use for polar solvent-oil separation
Assignee: ExxonMobil Technology and Engineering Co
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Filing: 1983-12-14
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Granted: 1985-09-17
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Expires: 2003-12-14
Abstract
Abstract It has been discovered that cellulose acetate membranes, fabricated using nonaqueous solvent systems, can be used for the separation of polar solvents, especially ketone dewaxing solvents from dewaxed oil. The cellulose acetate membranes so prepared are of a reduced acetyl content and exhibit very good resistance to ketone solvents. The specific fabrication procedure avoids exposing the cellulose acetate to even transient mixtures of ketone and alcohol or ketone and water. Although the cellulose acetate polymer is insoluble in pure water, alcohol, or ketone it is soluble in mixtures of ketone-alcohol and ketone-water. The resulting membrane is an effective means for separating ketone dewaxing solvent from dewaxed oil.
Inventors
- 👤 David L. Wernick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:18
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/08; B01D71/12; B01D71/14; B01D71/16; B01D67/00; B01D67/0002; B01D67/0009; B01D67/0011; B01D67/00111; B01D67/0081; B01D67/0083; B01D2323/00; B01D2323/12; B01D2323/30
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
215 words
A method for producing a cellulose 1.7-1.8 acetate membrane comprising: (a) dissolving 5 to 40 weight percent cellulose 1.7-1.8 acetate polymer in a dual casting solvent system comprising 15 to 50 weight percent solvent A and 20 to 80 weight percent solvent B wherein solvent A is more volatile than solvent B and wherein solvent B is a nonsolvent for the polymer while solvent A is either a solvent or nonsolvent for the polymer, but the mixture A plus B is a solvent for the polymer; (b) casting a film using the solution of step (a); (c) evaporating a portion of the more volatile solvent A from the film; and (d) gelling the partially evaporated film in a gelation solvent C which does not dissolve the polymer but is miscible with solvents A and B and further wherein the solvent combination of B+C is a nonsolvent for the polymer, wherein solvent A possesses three dimensional solubility parameters in the range of δ D =7 to 10, δ P =1 to 10 and δ H =6 to 12 and solvents B and C possess three dimensional solubility parameters in the range of δ D =7 to 10, δ P =0 to 10 and δ H <2.5, wherein all δ's are in (cal/cm 3 ) 1/2 .
Claim 2
Independent Claim
215 words
A method for producing a cellulose 1.7-1.8 acetate membrane comprising: (a) dissolving 5 to 40 weight percent cellulose 1.7-1.8 acetate polymer in a dual casting solvent system comprising 15 to 50 weight percent solvent A and 20 to 80 weight percent solvent B wherein solvent A is more volatile than solvent B and wherein solvent B is a nonsolvent for the polymer while solvent A is either a solvent or nonsolvent for the polymer, but the mixture A plus B is a solvent for the polymer; (b) casting a film using the solution of step (a); (c) evaporating a portion of the more volatile solvent A from the film; and (d) gelling the partially evaporated film in a gelation solvent C which does not dissolve the polymer but is miscible with solvents A and B and further wherein the solvent combination of B+C is a nonsolvent for the polymer, wherein solvent A possesses three dimensional solubility parameters in the range of δ D =7 to 10, δ P =1 to 10 and δ H =6 to 12 and solvents B and C possess three dimensional solubility parameters in the range of δ D =7 to 10, δ P =0 to 10 and δ H <2.5, wherein all δ's are in (cal/cm 3 ) 1/2 .
Claim 3
Dependent Claim
90 words
The process of claim 1 further comprising the step of annealing the gelled membrane in a solvent D which is the same as, or is miscible with, solvent C, which does not dissolve the polymer and wherein the solvent pair D+C (if D is different from C) is not a solvent for the polymer, wherein solvent D possesses three dimensional solubility parameters in the range of δ D =7 to 10, δ P =0 to 10 and δ H <2.5 wherein all δ's are in (cal/cm 3 ) 1/2 .
Claim 4
Dependent Claim
35 words
The process of claim 1 wherein solvent A is selected from methanol, ethanol, propanol, and isopropanol, and solvents B, C and D are selected from cyclohexanone, propylene carbonate, methyl isobutyl ketone, tetralin, chlorobenzene and toluene.
References Cited (Backward Citations)
US3140256A
Cited
US3673084A
Cited
US3412184A
Cited
US3483282A
Cited
GB1272574A
Cited
US3585126A
Cited
US3620970A
Cited
US3669954A
Cited
US3837900A
Cited
US3864289A
Cited
US3762566A
Cited
US3884801A
Cited
US3878276A
Cited
DE2413157A1
Cited
US4186238A
Cited
US4200558A
Cited
US4194024A
Cited
US4171987A
Cited
GB1430323A
Cited
JPS50136356A
Cited
JPS5382670A
Cited
US4130403A
Cited
US4145295A
Cited
JPS553859A
Cited
JPS5524506A
Cited
US4239545A
Cited
US4305824A
Cited
EP0012630A1
Cited
JPS56119809A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-09-16 | 1989-03-18 | 1989-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-16 | 1993-03-18 | 1993-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-16 | 1997-03-18 | 1997-09-17 | $7700.00 | Window Closed / Lapsed |