US4178157A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for manufacturing a filter of electrically charged electret fiber material and electret filters obtained according to said method
Assignee: 3M Co
•
Filing: 1977-12-21
•
Granted: 1979-12-11
•
Expires: 1997-12-21
Abstract
Abstract A method for forming a filter of electrically charged electret fiber material, consisting of a high molecular weight, nonpolar polymeric substance, comprising drawing, charging, and fibrillating a foil of said high molecular weight substance. The fibrillated foil is wound and then crimping is effected.
Inventors
- 👤 Jan van Turnhout
- 👤 Johannes C. Rieke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:06
CPC Classifications
D; D04; D04H; D04H13/00; D04H13/02; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/1607; B01D39/1623; B01D39/163; D04H1/00; D04H1/04; D04H1/06; D04H1/40; D04H1/42; D04H1/4282; D04H1/4291; B01D2239/00; B01D2239/04; B01D2239/0435; B01D2239/06; B01D2239/0604; B01D2239/0636; B01D2239/069; B01D2239/0695; B01D2239/10; Y; Y10; Y10S; Y10S264/00; Y10S264/48; Y10S55/00; Y10S55/05; Y10S55/39; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2922
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
86 words
A method for manufacturing a filter of electrically charged electret fiber material, consisting of a high-molecular weight, non-polar polymeric substance, comprising the steps of: continuously supplying a foil of said substance, drawing, charging and fibrillating of the foil and the processing of the thus obtained filter material into a filter, selecting the foil and/or the type of drawing to manufacture spontaneously crimpable fiber material, winding said material in uncrimped condition to a fibrous package and subsequently effecting crimping to interlock the fibers of said fibrous package.
Claim 2
Independent Claim
86 words
A method for manufacturing a filter of electrically charged electret fiber material, consisting of a high-molecular weight, non-polar polymeric substance, comprising the steps of: continuously supplying a foil of said substance, drawing, charging and fibrillating of the foil and the processing of the thus obtained filter material into a filter, selecting the foil and/or the type of drawing to manufacture spontaneously crimpable fiber material, winding said material in uncrimped condition to a fibrous package and subsequently effecting crimping to interlock the fibers of said fibrous package.
Claim 3
Dependent Claim
15 words
A method according to claim 1, further comprising the step of heat treating the filter.
Claim 4
Dependent Claim
29 words
A method according to claim 1, wherein a foil is used in which at least two substances with different drawing or crimping characteristics are incorporated in a non-homogeneous mixture.
Claim 5
Dependent Claim
20 words
A method according to claim 3, wherein a foil is used being a laminate of said at least two substances.
Claim 6
Dependent Claim
21 words
A method according to claim 1, further comprising the step of deforming the foil during or after the step of drawing.
Claim 7
Dependent Claim
10 words
A filter produced by the method according to claim 1.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-12-10 | 1983-06-11 | 1983-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-10 | 1987-06-11 | 1987-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-10 | 1991-06-11 | 1991-12-11 | $7700.00 | Window Closed / Lapsed |