US3640839A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter paper for oil filters
Assignee: Tokyo Roki Co Ltd
•
Filing: 1968-09-05
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Granted: 1972-02-08
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Expires: 1988-09-05
Abstract
Abstract A filter paper for oil filters has a coarse web capable of passing particles of granular size of about 40 Mu maximum diameter and a plurality of dense web strips superposed in parallel upon the coarse web and combined therewith at fixed intervals, the dense web being capable of passing particles of granular size of about 15 Mu maximum diameter.
Inventors
- 👤 Tuguo Ochiai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:04
CPC Classifications
B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/18
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
36 words
A filter paper in accordance with claim 1, wherein the ratio of planar exposed surface area of the plurality of dense web strips to that of coarse web is in the range of 10:5 to 10:10.
References Cited (Backward Citations)
US2675127A
Cited
US3322617A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-07 | 1975-08-09 | 1976-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-07 | 1979-08-09 | 1980-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-07 | 1983-08-09 | 1984-02-08 | $7700.00 | Window Closed / Lapsed |