US4192838A
Expired / Lapsed
US
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Process for producing filter material
Assignee: Celanese Corp
•
Filing: 1978-08-28
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Granted: 1980-03-11
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Expires: 1998-08-28
Abstract
Abstract A non-woven cellulose ester fibrous filter sheet material comprising cellulose ester staple fibers and cellulose ester fibrets which exhibits improved filtration properties and the method of its preparation.
Inventors
- 👤 Charles H. Keith
- 👤 Richard O. Tucker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:30
CPC Classifications
A; A24; A24D; A24D3/00; A24D3/06; A24D3/08; A24D3/10; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/18; D; D01; D01D; D01D5/00; D01D5/06; D01F; D01F2/00; D01F2/24; D01F2/28; D21; D21H; D21H13/00; D21H13/02; D21H13/06
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
114 words
A process for the production of an opaque, voidy, fibrillar structure which comprises the steps of preparing a dope formulation containing a cellulose ester dissolved in a solvent which consists essentially of non-solvent liquid which is miscible with the solvent for said cellulose ester and a co-miscible organic solvent for said cellulose ester; passing the cellulose ester dope through a capillary needle situated in or above the throat of a venturi through which a coagulation liquid is passed, at a velocity sufficient to attenuate the extrudate issuing from said capillary needle, said coagulation liquid being a non-solvent for said cellulose ester, whereby a precipitate is obtained in the form of a cellulose ester fibret.
Claim 2
Dependent Claim
114 words
A process for the production of an opaque, voidy, fibrillar structure which comprises the steps of preparing a dope formulation containing a cellulose ester dissolved in a solvent which consists essentially of non-solvent liquid which is miscible with the solvent for said cellulose ester and a co-miscible organic solvent for said cellulose ester; passing the cellulose ester dope through a capillary needle situated in or above the throat of a venturi through which a coagulation liquid is passed, at a velocity sufficient to attenuate the extrudate issuing from said capillary needle, said coagulation liquid being a non-solvent for said cellulose ester, whereby a precipitate is obtained in the form of a cellulose ester fibret.
Claim 3
Dependent Claim
12 words
The process of claim 1 wherein said cellulose ester is cellulose acetate.
Claim 4
Dependent Claim
11 words
The process of claim 2, wherein said coagulation liquid is water.
Claim 5
Dependent Claim
20 words
The process of claim 3, wherein the precipitate is homogenized to reduce the particle size of the precipitated cellulose ester.
References Cited (Backward Citations)
US2925412A
Cited
US2875473A
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US2988782A
Cited
US3342921A
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US3785918A
Cited
US3885014A
Cited
US3879335A
Cited
US3833438A
Cited
US4040856A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-03-11 | 1983-09-10 | 1984-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-11 | 1987-09-10 | 1988-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-11 | 1991-09-10 | 1992-03-11 | $7700.00 | Window Closed / Lapsed |