US4944854A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electret process and products
Assignee: Invista North America LLC
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Filing: 1985-09-30
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Granted: 1990-07-31
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Expires: 2005-09-30
Abstract
Abstract Continuous processes for the preparation of electrets and the products produced thereby, including filter fabrics, are disclosed. The process employs a continuous film or continuous filaments in the form of a tightly packed warp having a warp density as determined by light transmission of not more than 40%. The continuous film or continuous filament in the form of a tightly packed warp are continuously fed one or more times through a corona charging station having electrodes disposed on both sides of the material being treated, the material being treated being simultaneously heated while being subjected to a corona discharge of from 6 KV to 20 KV direct current.
Inventors
- 👤 Clinton D. Felton
- 👤 Baylor D. Gibson
- 👤 Charles E. Jamison
- 👤 William O. McWhorter
- 👤 George A. Serad
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:36
CPC Classifications
B; B01; B01D; B01D39/00; B01D39/08; B01D39/083; H; H01; H01G; H01G7/00; H01G7/02; H01G7/021; H01G7/023; B01D2239/00; B01D2239/04; B01D2239/0435; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2973
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
76 words
A method for the manufacture of electrets which comprises passing a polymeric film or a warp beam of tightly packed synthetic yarn having a warp density as determined by light transmission of not more than 40% through a corona charging station a plurality of times while in a heated and tensioned condition, said corona charging station subjecting the film or yarn to corona discharge treatments generated between an upper grid member and a lower grid member.
Claim 2
Independent Claim
76 words
A method for the manufacture of electrets which comprises passing a polymeric film or a warp beam of tightly packed synthetic yarn having a warp density as determined by light transmission of not more than 40% through a corona charging station a plurality of times while in a heated and tensioned condition, said corona charging station subjecting the film or yarn to corona discharge treatments generated between an upper grid member and a lower grid member.
Claim 3
Dependent Claim
17 words
The method of claim 1 wherein said polymeric film or yarn is a polyolefinic film or yarn.
Claim 4
Dependent Claim
15 words
The method of claim 1 wherein said polymeric film or yarn is a polypropylene yarn.
Claim 5
Dependent Claim
30 words
The method of claim 1 wherein said plurality of corona discharge treatments each employ direct current corona discharge in the range of from 6 K. volts to 20 K. volts.
Claim 6
Dependent Claim
22 words
The method of claim 1 wherein said corona discharge is generated by applying a charge of common polarity to both grid members.
Claim 7
Dependent Claim
29 words
The method of claim 1 wherein said corona discharge is generated by applying a negative charge to one grid member and a positive charge to the other grid member.
Claim 8
Dependent Claim
14 words
The method of claim 6 wherein said continuous filament is a polyolefin continuous filament.
Claim 9
Dependent Claim
14 words
The method of claim 1 wherein said continuous filament is a polyolefin continuous filament.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-30 | 1994-01-29 | 1994-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-30 | 1998-01-29 | 1998-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-30 | 2002-01-29 | 2002-07-31 | $7700.00 | Window Closed / Lapsed |