US4874399A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electret filter made of fibers containing polypropylene and poly(4-methyl-1-pentene)
Assignee: 3M Co
•
Filing: 1988-01-25
•
Granted: 1989-10-17
•
Expires: 2008-01-25
Abstract
Abstract A fibrous electret filter better sustains electret filtration enhancement upon exposure to aerosol oils when made of fibers containing polypropylene and at least one percent by weight of poly(4-methyl-1-pentene). Even better stability is attained when the poly(4-methyl-1-pentene) content of the electret filter is ten percent by weight of total polyolefin. When used as an air filter, such as in a respirator, the electret filter has surprisingly better filtration performance than does a comparable electret filter made of 100% polypropylene fibers. The electret filter can be made either of melt-blown microfibers or of fibers of fibrillated film.
Inventors
- 👤 John F. Reed
- 👤 Marvin E. Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:56
CPC Classifications
B; B01; B01D; B01D39/00; B01D39/02; B01D39/04; B03; B03C; B03C3/00; B03C3/28; B01D39/14; B01D39/16; B01D39/1607; B01D39/1623; H; H01; H01G; H01G7/00; H01G7/02; H01G7/021; H01G7/023; Y; Y10; Y10S; Y10S55/00; Y10S55/35; Y10S55/39
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
29 words
Method of removing particulate matter from a gaseous fluid comprising passing the fluid through an electret filter comprising electret fibers containing at least one percent by weight of poly(4-methyl-1-pentene).
Claim 2
Dependent Claim
29 words
Method of removing particulate matter from a gaseous fluid comprising passing the fluid through an electret filter comprising electret fibers containing at least one percent by weight of poly(4-methyl-1-pentene).
Claim 3
Dependent Claim
28 words
Method as defined in claim 1 wherein the said electret fibers comprise by weight from 80 to 99 percent of polypropylene and from 1 to 20 percent poly(4-methyl-1-pentene).
Claim 4
Dependent Claim
13 words
Method as defined in claim 1 wherein said electret fibers comprise melt-blown microfibers.
Claim 5
Dependent Claim
22 words
Electret filter comprising electret fibers containing polypropylene and at least one percent by weight of poly(4-methyl-1-pentene) per 100 parts of total polyolefin.
Claim 6
Dependent Claim
22 words
Electret filter comprising electret fibers containing polypropylene and at least one percent by weight of poly(4-methyl-1-pentene) per 100 parts of total polyolefin.
Claim 7
Dependent Claim
26 words
Electret filter as defined in claim 4 wherein the amount of the poly(4-methyl-1-pentene) is up to 50 parts by weight per 100 parts of total polyolefin.
Claim 8
Dependent Claim
17 words
Electret filter as described in claim 5 wherein a portion of the electret fibers are 100% polypropylene.
Claim 9
Dependent Claim
19 words
Electret filter as defined in claim 4 wherein the electret fibers are mixtures of melt-blown microfibers and fibrillated film.
Claim 10
Dependent Claim
19 words
Electret filter as defined in claim 4 wherein the electret fibers are mixtures of melt-blown microfibers and staple fibers.
Claim 11
Dependent Claim
26 words
Electret filters as defined in claim 4 wherein the amount of the poly(4-methyl-1-pentene) is up to 20 parts by weight per 100 parts of total polyolefin.
Claim 12
Dependent Claim
22 words
Electret filter as defined in claim 4 wherein each of the electret fibers has a polypropylene core and poly(4-methyl-1-pentene) at its surface.
Claim 13
Dependent Claim
14 words
Electret filter as defined in claim 4 wherein the electret fibers are fibrillated film.
Claim 14
Dependent Claim
23 words
Electret filter as defined in claim 11 wherein the electret fibers comprise strata, one of which is 100% polypropylene while another comprises poly(4-methyl-1-pentene).
Claim 15
Dependent Claim
19 words
Electret air filter element comprising polyolefin electret fibers, at least one percent by weight of the polyolefin being poly(4-methyl-1-pentene).
Claim 16
Dependent Claim
19 words
Electret air filter element comprising polyolefin electret fibers, at least one percent by weight of the polyolefin being poly(4-methyl-1-pentene).
Claim 17
Dependent Claim
21 words
Electret air filter element as defined in claim 13 wherein at least 50 percent by weight of the polyolefin is polypropylene.
Claim 18
Dependent Claim
28 words
Electret air filter element as defined in claim 14 wherein the amount of the poly(4-methyl-1-pentene) is up to 20 parts by weight per 100 parts of total polyolefin.
Claim 19
Dependent Claim
21 words
Electret air filter element as defined in claim 15 wherein at least 80 percent by weight of the polyolefin is polypropylene.
Claim 20
Dependent Claim
22 words
Electret air filter element as defined in claim 13, the basis weight of which is from 5 to 1000 g/m 2 .
Claim 21
Dependent Claim
16 words
Electret air filter element as defined in claim 13 wherein said filter element comprises a respirator.
Claim 22
Dependent Claim
14 words
Respirator as defined in claim 18 and further comprising a semi-rigid, porous, cup-shaped shell.
Claim 23
Dependent Claim
13 words
Respirator as defined in claim 18 wherein the electret fibers comprise melt-blown microfibers.
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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) | 1992-10-16 | 1993-04-17 | 1993-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-16 | 1997-04-17 | 1997-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-16 | 2001-04-17 | 2001-10-17 | $7700.00 | Window Closed / Lapsed |