US3880966A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Corona treated microporous film
Assignee: Celanese Corp
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Filing: 1973-08-27
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Granted: 1975-04-29
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Expires: 1993-08-27
Abstract
Abstract Crystalline elastic polymeric films having a crystallinity of at least 20 percent and an elastic recovery of at least 40 percent after subjection to a 50 percent extension at 25*C. and 65 percent relative humidity are subjected to a corona discharge treatment rendering the films permeable. The films are subsequently rendered microporous by stretching and heat setting operations to further increase permeability. Or this treatment to render the crystalline elastic film microporous may be first used on the film before the corona treatment. The films are useful as filters, flow control devices, and the like.
Inventors
- 👤 Daniel Zimmerman
- 👤 Stephen Schulze
- 👤 Stanley Wolfowitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:55
CPC Classifications
B; B29; B29D; B29D7/00; B01; B01D; B01D67/00; B01D67/0081; B01D67/009; B01D69/00; B01D69/12; B01D69/125; B01D69/127; B01D71/00; B01D71/06; B01D71/26; B01D71/261; B01D71/262; B01D71/48; B01D71/56; B01D71/72; B26; B26F; B26F1/00; B26F1/26; B26F1/28; B29C; B29C59/00; B29C59/10
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
155 words
A PROCESS FOR PREPARING A MICROPOROUS FILM SELECTED FROM THE GROUP CONSISTING OF POLYOLEFINS, POLYACETAL HOMOPOLYMERS AND COPOLYMERS, POLYALKYLENE SULFIDES, POLYARYLENE OXIDES, POLYAMIDES AND POLYESTERS OF INCREASED POROSITY AND PORE SIZE WHICH COMPRISE SUBJECTING TO A CORONA DISCHARGE TREATMENT A CRYSTALLINE NON-POROUS ELASTUC STARTING FILM HAVING AN ELASTIC RECOVERY WHEN SUBJECTED TO A 50 PERCENT EXTENTION AT 25*C. AND 65 PERCENT RELATIVE HUMIDITY OF AT LEAST 20 PERCENT, SAID COR AND A PERCENT CRYSTALLINITY OF AT LEAST 20 PERCENT, SAID CORONA DISCHARGE TREATMENT SUFFICIENT TO PERFORATE SAID FILM WITH HOLES OF UP TO ABOUT 20 MICRONS, SAID CORONA DISCHARGE CARRIED OUT USING A VOLTAGE OF UP TO ABOUT 15,000 VOLTS, AND RENDERING SAID CORONA-TREATED FILM MICROPOROUS BY A SERIES OF STEPS WHICH COMPRISE COLD STRETCHING THE FILM TO A LENGTH 10 TO 300 PERCENT OF ITS ORIGINAL LENGTH AT A TEMPERATURE LESS THAN THE TEMPERATURE AT WHICH MELTING OF THE FILM BEGINS AND HEAT SETTING.
Claim 2
Dependent Claim
155 words
A PROCESS FOR PREPARING A MICROPOROUS FILM SELECTED FROM THE GROUP CONSISTING OF POLYOLEFINS, POLYACETAL HOMOPOLYMERS AND COPOLYMERS, POLYALKYLENE SULFIDES, POLYARYLENE OXIDES, POLYAMIDES AND POLYESTERS OF INCREASED POROSITY AND PORE SIZE WHICH COMPRISE SUBJECTING TO A CORONA DISCHARGE TREATMENT A CRYSTALLINE NON-POROUS ELASTUC STARTING FILM HAVING AN ELASTIC RECOVERY WHEN SUBJECTED TO A 50 PERCENT EXTENTION AT 25*C. AND 65 PERCENT RELATIVE HUMIDITY OF AT LEAST 20 PERCENT, SAID COR AND A PERCENT CRYSTALLINITY OF AT LEAST 20 PERCENT, SAID CORONA DISCHARGE TREATMENT SUFFICIENT TO PERFORATE SAID FILM WITH HOLES OF UP TO ABOUT 20 MICRONS, SAID CORONA DISCHARGE CARRIED OUT USING A VOLTAGE OF UP TO ABOUT 15,000 VOLTS, AND RENDERING SAID CORONA-TREATED FILM MICROPOROUS BY A SERIES OF STEPS WHICH COMPRISE COLD STRETCHING THE FILM TO A LENGTH 10 TO 300 PERCENT OF ITS ORIGINAL LENGTH AT A TEMPERATURE LESS THAN THE TEMPERATURE AT WHICH MELTING OF THE FILM BEGINS AND HEAT SETTING.
Claim 3
Dependent Claim
46 words
The process of claim 1 wherein after cold stretching the film is hot stretched 10 to 300% of its original length at a temperature above the temperature at which melting begins, the total cold and hot stretching being within 10 to 300% of the original length.
Claim 4
Dependent Claim
18 words
The process of claim 1 wherein said starting film has a thickness of about 0.005 to 0.01 inch.
Claim 5
Dependent Claim
10 words
The process of claim 1 wherein said film is polypropylene.
Claim 6
Dependent Claim
10 words
The process of claim 1 wherein said film is polyethylene.
Claim 7
Dependent Claim
14 words
The process of claim 1 wherein said film is a polyacetal homopolymer or copolymer.
Claim 8
Dependent Claim
25 words
The process of claim 1 wherein said corona discharge is carried out at a voltage in the range of between about 13,000 and 15,000 volts.
Claim 9
Dependent Claim
28 words
The process of claim 7 wherein said corona discharge treatment of said film occurs at a rate of about 3 to 5 seconds per square inch of film.
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) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |