US5800769A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming an electrostatic fibrous filter web
Assignee: Individual
•
Filing: 1997-05-08
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Granted: 1998-09-01
•
Expires: 2017-05-08
Abstract
Abstract There is provided a method for forming a nonwoven electret fiber filter with a nonwoven web of electret fibers needle-punched to an open scrim support. The scrim support material has individual discrete open areas with an average cross-sectional area as viewed from the plane of the filter media of at least 0.25 mm2, preferably 1.0 mm2, and a pressure drop across the scrim support, without the filter web, of less than 1.5 mm H2O measured at 98.4 meters/min gaseous face velocity. The resulting filter has enhanced lifetimes, a low pressure drop and high filtration efficiencies.
Inventors
- 👤 Thomas E. Haskett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:23
CPC Classifications
B; B32; B32B; B32B5/00; B32B5/22; B32B5/24; B32B5/26; B01; B01D; B01D35/00; B01D35/06; B01D39/00; B01D39/08; B01D39/083; B01D39/086; B01D46/00; B01D46/0001; B01D46/0027; B01D46/0032; B01D46/10; B01D46/16; B03; B03C; B03C3/00; B03C3/28; B32B38/00; B32B38/0008; B32B5/02; B32B5/022; B32B5/028; D; D04; D04H; D04H1/00; D04H1/40; D04H1/44; D04H1/46; D04H1/498; D04H3/00; D04H3/02; D04H3/04; B01D2239/00; B01D2239/04; B01D2239/0435; B01D2239/06; B01D2239/0604; B01D2239/0618; B01D2239/0627; B01D2239/065; B01D2239/0654; B01D2239/0659; B01D2239/0686; B01D2239/069; B01D2239/12; B01D2239/1291; B32B2262/00; B32B2262/02; B32B2262/0253; Y; Y10; Y10S; Y10S264/00; Y10S264/48; Y10S55/00; Y10S55/05; Y10S55/39; Y10T; Y10T442/00; Y10T442/10; Y10T442/102; Y10T442/159; Y10T442/16
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
113 words
A method for forming an electret nonwoven filter web comprising the steps of: a) providing at least one nonwoven filter web; b) joining the at least one filter web to a reinforcement scrim said reinforcement scrim having discrete open areas where the average cross-sectional area in the plane of the filter of the open areas is at least 0.25 mm 2 and said scrim having an overall pressure drop of less than 1.5 mm H 2 O at 98.4 meters/min; c) needle punching the at least one filter web and reinforcement scrim to form a filter; and d) providing at least some of the filter fibers of the filter web with electret charges.
Claim 2
Independent Claim
113 words
A method for forming an electret nonwoven filter web comprising the steps of: a) providing at least one nonwoven filter web; b) joining the at least one filter web to a reinforcement scrim said reinforcement scrim having discrete open areas where the average cross-sectional area in the plane of the filter of the open areas is at least 0.25 mm 2 and said scrim having an overall pressure drop of less than 1.5 mm H 2 O at 98.4 meters/min; c) needle punching the at least one filter web and reinforcement scrim to form a filter; and d) providing at least some of the filter fibers of the filter web with electret charges.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein the electret charged fibers of the filter web are formed by fibrillation of an electrostatically charged film.
Claim 4
Dependent Claim
17 words
The method of claim 2 wherein the electret charged fibers are charged while in the filter web.
Claim 5
Dependent Claim
16 words
The method of claim 1 wherein the electret charged fibers are charged by a corona discharge.
Claim 6
Dependent Claim
14 words
The method of claim 1 wherein the electret charged fibers are charged by tribo-charging.
Claim 7
Dependent Claim
19 words
The method of claim 1 wherein the reinforcement scrim is an inner layer between two outer filter web layers.
Claim 8
Dependent Claim
17 words
The method of claim 1 wherein the at least one nonwoven filter web is formed by carding.
Claim 9
Dependent Claim
28 words
The method of claim 1 wherein the electret charge fibers are a polypropylene polymer or copolymer fiber and the scrim reinforcement is a net of cross laminated fibers.
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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) | 2001-08-31 | 2002-03-02 | 2002-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-08-31 | 2006-03-02 | 2006-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-08-31 | 2010-03-02 | 2010-09-01 | $7700.00 | Window Closed / Lapsed |