US4287249A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Textured surface polypropylene film
Assignee: General Electric Co
•
Filing: 1979-04-16
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Granted: 1981-09-01
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Expires: 1999-04-16
Abstract
Abstract A thin polypropylene film with improved surface impregnation properties for dielectric fluids is disclosed. The film has one predetermined textured surface consisting essentially of fibroids intertwined and overlapping, and coextensive and uniform over its continuous length and is characterized by a space factor of above about 5%.
Inventors
- 👤 John W. Eustance
- 👤 Stanley Y. Hobbs
- 👤 Emilie L. Carley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:44
CPC Classifications
B; B29; B29D; B29D7/00; B29D7/01; B29C; B29C55/00; B29C55/28; B29C59/00; B32; B32B; B32B27/00; B32B27/32; H; H01; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/14; H01G4/18; H01G4/32; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/31
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
73 words
An improved flat film with improved surface impregnation properties for dielectric fluids which comprises a thin polypropylene film having one predetermined textured surface which is coextensively and uniformly covered by an overlapping pattern of fibroid irregularities comprising predominantly a stretched layer of Type I and Type II polypropylene crystal structure, and said film being characterized by a space factor of greater than about 5% and a haze measurement of greater than about 20%.
Claim 2
Dependent Claim
73 words
An improved flat film with improved surface impregnation properties for dielectric fluids which comprises a thin polypropylene film having one predetermined textured surface which is coextensively and uniformly covered by an overlapping pattern of fibroid irregularities comprising predominantly a stretched layer of Type I and Type II polypropylene crystal structure, and said film being characterized by a space factor of greater than about 5% and a haze measurement of greater than about 20%.
Claim 3
Dependent Claim
42 words
The film of claim 1, produced by the steps of extruding polypropylene into a stalk, cooling the stalk to crystallize the polypropylene, passing the stalk through a heating zone and biaxially stretching the stalk through a heating zone into a thin film.
Claim 4
Dependent Claim
58 words
The film of claim 2, wherein said stalk emanating from the extruder has a section primarily temperature controlled to the stalk velocity to cause extensive, continuous and uniform spherulite formation wtih a predominantly type III polypropylene crystal structure on the outer surface of the stalk, which upon subsequent inflation of the stalk causes the desired texture to occur.
Claim 5
Dependent Claim
12 words
The film of claim 1, wherein said polypropylene consists of isotactic polypropylene.
Claim 6
Dependent Claim
49 words
The film of claim 4, wherein one surface of the film is substantially smooth and flat and opposite surface is a textured surface which is substantially uniform over the film to provide a space factor of above about 10% of the film which is between 12.5μ and 20μ thickness.
Claim 7
Dependent Claim
17 words
The film of claim 4, wherein said film has a textured surface as shown in FIG. 3.
Claim 8
Dependent Claim
17 words
The film of claim 4, wherein said film has a textured surface as shown in FIG. 4.
Claim 9
Dependent Claim
17 words
The film of claim 4, wherein said film has a textured surface as shown in FIG. 5.
Claim 10
Dependent Claim
34 words
The film of claim 4, wherein the textured surface consists essentially of raised fibroids elevated 2 to 3 microns above the ordinary gage thickness of the film and coextensive over said one textured surface.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-08-31 | 1985-03-02 | 1985-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-31 | 1989-03-02 | 1989-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-31 | 1993-03-02 | 1993-09-01 | $7700.00 | Window Closed / Lapsed |