US3839240A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High melt index microporous films
Assignee: Celanese Corp
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Filing: 1973-05-21
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Granted: 1974-10-01
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Expires: 1993-05-21
Abstract
Abstract Microporous films having improved permeability and heat stability are prepared from a precursor film which is based upon a polymer having a melt index of about 5 to about 50 and a weight average molecular weight of about 100,000 to 240,000. Such films are useful as filters, flow control devices and in other areas where improved heat stability and permeability and increased pore sizes are desired.
Inventors
- 👤 D Zimmerman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:56
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/26; B01D71/262; B01D39/00; B01D39/14; B01D39/16; B01D39/1692; B01D67/00; B01D67/0002; B01D67/0023; B01D67/0025; B01D67/0027; B29; B29C; B29C55/00; B29C55/02; B29C55/04; B29C55/06; B29C55/065; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10S521/00; Y10S521/918
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
134 words
IN A PROCESS FOR PREPARING AN OPEN-CELLED MICROPOROUS POLYPROPYLENE FILM UTILIZING A NON-POROUS CRYSTALLINE ELASTIC POLYPROPYLENE STARTING FILM HAVING AN ELASTIC RECOVERY FROM A 50 PERCENT EXTENTION AT 25*C. OF AT LEAST 40 PERCENT AND A PERCENT CRYSTALLINITY OF AT LEAST 20 PERCENT, WHICH PROCESS COMPRISES STRETCHING SAID STARTING FILM UNTIL AN OPEN-CELLED MICROPOROUS STRUCTURE IS FORMED IN SAID FILM AND HEAT SETTING THE RESULTING STRETCHED FILM, TO STABILIZE THE OPEN-CELL STRUCTURE IN THE STRETCHED FILM, TO IMPROVEMENT WHICH COMPRISES UTILIZING A POLYPROPYLENE POLYMER HAVING A MELT INDEX IN THE RANGE OF FROM ABOUT 8 TO ABOUT 30 AND A WEIGHT AVERAGE MOLECULAR WEIGHT OF ABOUT 100,000 TO 240,000 WHEREIN THE RESULTING FILM EXHIBITS IMPROVED HEAT STABILITY, IMPROVED PERMEABILITY AND LARGER PORES SIZES OVER CORRESPONDING FILMS HAVING LOWER MELT INDEXES AND HIGHER MOLECULAR WEIGHTS.
Claim 2
Dependent Claim
134 words
IN A PROCESS FOR PREPARING AN OPEN-CELLED MICROPOROUS POLYPROPYLENE FILM UTILIZING A NON-POROUS CRYSTALLINE ELASTIC POLYPROPYLENE STARTING FILM HAVING AN ELASTIC RECOVERY FROM A 50 PERCENT EXTENTION AT 25*C. OF AT LEAST 40 PERCENT AND A PERCENT CRYSTALLINITY OF AT LEAST 20 PERCENT, WHICH PROCESS COMPRISES STRETCHING SAID STARTING FILM UNTIL AN OPEN-CELLED MICROPOROUS STRUCTURE IS FORMED IN SAID FILM AND HEAT SETTING THE RESULTING STRETCHED FILM, TO STABILIZE THE OPEN-CELL STRUCTURE IN THE STRETCHED FILM, TO IMPROVEMENT WHICH COMPRISES UTILIZING A POLYPROPYLENE POLYMER HAVING A MELT INDEX IN THE RANGE OF FROM ABOUT 8 TO ABOUT 30 AND A WEIGHT AVERAGE MOLECULAR WEIGHT OF ABOUT 100,000 TO 240,000 WHEREIN THE RESULTING FILM EXHIBITS IMPROVED HEAT STABILITY, IMPROVED PERMEABILITY AND LARGER PORES SIZES OVER CORRESPONDING FILMS HAVING LOWER MELT INDEXES AND HIGHER MOLECULAR WEIGHTS.
Claim 3
Dependent Claim
23 words
The process of claim 1 wherein said stretching operation comprises the steps of cold stretching and hot stretching the crystalline elastic polypropylene film.
References Cited (Backward Citations)
US3679538A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-30 | 1978-04-01 | 1978-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-30 | 1982-04-01 | 1982-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-30 | 1986-04-01 | 1986-10-01 | $7700.00 | Window Closed / Lapsed |