US4948515A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter for liquid and method of filtering liquid
Assignee: Toray Industries Inc
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Filing: 1988-12-22
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Granted: 1990-08-14
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Expires: 2008-12-22
Abstract
Abstract A method for filtering liquids having a dielectric constant less than 10 is disclosed. The method includes the step of filtering a liquid through a porous layer of an electret, the electret consisting of a fibrous sheet having a surface charge density of at least 5×10 -11 coulombs/cm 2 , wherein on the upstream side of the electret is laminated another porous layer having at least a porosity or an average fiber diameter greater than that of the electret layer. The upstream layer may consist of either a fibrous electret layer, or an uncharged fibrous layer.
Inventors
- 👤 Yoshiharu Okumura
- 👤 Katsutoshi Ando
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:01
CPC Classifications
B; B01; B01D; B01D35/00; B01D35/06; B01D39/00; B01D39/14; B01D39/16; B01D39/1607; B01D39/1623; B03; B03C; B03C5/00; B03C5/02; H; H01; H01G; H01G7/00; H01G7/02; H01G7/021; H01G7/023
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
87 words
A method of filtering a liquid comprising the step of filtering a liquid having a dielectric constant of less than 10 through a porous layer of electret, wherein said porous layer comprises a fibrous sheet which has a surface charge density of at least 5×10 -11 coulombs/cm 2 , wherein on the upstream side of said porous layer of electret is laminated another porous layer having at least either a porosity or an average fiber diameter that is greater than that of said porous layer of electret.
Claim 2
Independent Claim
87 words
A method of filtering a liquid comprising the step of filtering a liquid having a dielectric constant of less than 10 through a porous layer of electret, wherein said porous layer comprises a fibrous sheet which has a surface charge density of at least 5×10 -11 coulombs/cm 2 , wherein on the upstream side of said porous layer of electret is laminated another porous layer having at least either a porosity or an average fiber diameter that is greater than that of said porous layer of electret.
Claim 3
Dependent Claim
14 words
A method as in claim 1, wherein said fibrous sheet is a non-woven fabric.
Claim 4
Dependent Claim
22 words
A method as in claim 1, wherein the average fiber diameter of fibers constituting the fibrous sheet is smaller than 50 μm.
Claim 5
Dependent Claim
19 words
A method as in claim 1, wherein said fibrous sheet is a non-woven fabric prepared by a meltblowing process.
Claim 6
Dependent Claim
19 words
A process as in claim 1, wherein said fibrous sheet is a non-woven fabric prepared by a spunbonding process.
Claim 7
Dependent Claim
21 words
A process as in claim 1, wherein said porous layer of electret is a non-woven fabric prepared by a meltblowing process.
Claim 8
Dependent Claim
22 words
A process as in claim 1, wherein said another porous layer on the upstream side has been electrified to be an electret.
Claim 9
Dependent Claim
24 words
A method as in claim 1, wherein the laminated porous layers of the upstream side and the downstream side are adhered to each other.
Claim 10
Dependent Claim
12 words
A method as in claim 1, wherein said liquid is an oil.
Claim 11
Dependent Claim
13 words
A method as in claim 1, wherein said liquid is an organic solvent.
Claim 12
Dependent Claim
30 words
A method as in claim 1, wherein a pair of electrodes are arranged on the upstream side of said filter, and a voltage is applied between said pair of electrodes.
Claim 13
Dependent Claim
49 words
A method as in claim 1, wherein a pair of said filters are arranged in parallel with each other in the direction in which the liquid flows, two electrodes are arranged respectively on the outside of said pair of filters, and a voltage is applied between the two electrodes.
Claim 14
Independent Claim
97 words
A method of filtering a liquid comprising the step of filtering a liquid having a dielectric constant of less than 10 through a porous layer of electret, wherein said porous layer comprises a fibrous sheet which comprises a fibrous material obtained by slitting an electret film having a surface charge density of at least 5×10 -9 coulombs/cm 2 , wherein on the upstream side of said porous layer of electret is laminated another porous layer having at least either a porosity or an average fiber diameter that is greater than that of said porous layer of electret.
Claim 15
Independent Claim
97 words
A method of filtering a liquid comprising the step of filtering a liquid having a dielectric constant of less than 10 through a porous layer of electret, wherein said porous layer comprises a fibrous sheet which comprises a fibrous material obtained by slitting an electret film having a surface charge density of at least 5×10 -9 coulombs/cm 2 , wherein on the upstream side of said porous layer of electret is laminated another porous layer having at least either a porosity or an average fiber diameter that is greater than that of said porous layer of electret.
Claim 16
Dependent Claim
14 words
A method as in claim 13, wherein said fibrous sheet is a non-woven fabric.
Claim 17
Dependent Claim
22 words
A method as in claim 13, wherein the average fiber diameter of fibers constituting the fibrous sheet is smaller than 50 μm.
Claim 18
Dependent Claim
21 words
A process as in claim 13, wherein said porous layer of electret is a non-woven fabric prepared by a meltblowing process.
Claim 19
Dependent Claim
22 words
A process as in claim 13, wherein said another porous layer on the upstream side has been electrified to be an electret.
Claim 20
Dependent Claim
24 words
A method as in claim 13, wherein the laminated porous layers of the upstream side and the downstream side are adhered to each other.
Claim 21
Dependent Claim
12 words
A method as in claim 13, wherein said liquid is an oil.
Claim 22
Dependent Claim
13 words
A method as in claim 13, wherein said liquid is an organic solvent.
Claim 23
Dependent Claim
30 words
A method as in claim 13, wherein a pair of electrodes are arranged on the upstream side of said filter, and a voltage is applied between said pair of electrodes.
Claim 24
Dependent Claim
49 words
A method as in claim 13, wherein a pair of said filters are arranged in parallel with each other in the direction in which the liquid flows, two electrodes are arranged respectively on the outside of said pair of filters, and a voltage is applied between the two electrodes.
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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) | 1993-08-13 | 1994-02-12 | 1994-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-13 | 1998-02-12 | 1998-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-13 | 2002-02-12 | 2002-08-14 | $7700.00 | Window Closed / Lapsed |