US4283453A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Biaxially stretched polypropylene composite film and electrical insulating film made therefrom
Assignee: Hoechst AG
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Filing: 1979-11-29
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Granted: 1981-08-11
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Expires: 1999-11-29
Abstract
Abstract Disclosed is a biaxially stretched, composite polypropylene film suitable for use as an electrical insulating film, comprising a first layer comprising a first propylene polymer and having a maximum roughness height R z of its exposed surface of about 0.5 μm, and a second layer contiguous to the first layer comprising a second propylene polymer having a composition different from the first propylene polymer and having a roughness height R z on its exposed surface ranging between about 0.2 μm and 0.4 μm, with the composite film having a modulus of elasticity of at least about 2000 N/mm 2 in all directions of the plane of the film and a DC dielectric strength of at least about 650 V/μm. Also disclosed is a capacitor comprised of a plurality of these composite films having a metal surface layer and being laminated with one another.
Inventors
- 👤 Walter Siefried
- 👤 Siegfried Janocha
- 👤 Gunther Crass
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:57
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/32; B32B27/30; B32B27/302; B32B27/308; C; C08; C08J; C08J7/00; C08J7/04; C08J7/0427; H; H01; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/20; B29; B29K; B29K2995/00; B29K2995/0037; B29K2995/0072; B32B2255/00; B32B2255/10; B32B2255/20; B32B2255/205; B32B2307/00; B32B2307/20; B32B2307/206; B32B2307/50; B32B2307/51; B32B2307/514; B32B2307/518; B32B2307/538; B32B2323/00; B32B2323/10; B32B2457/00; B32B2457/16; C08J2323/00; C08J2323/02; C08J2323/10; C08J2323/12; C08J2423/00; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/29; Y10T428/2913; Y10T428/2933; Y10T428/294; Y10T428/31; Y10T428/31504; Y10T428/31678; Y10T428/31692; Y10T428/31855; Y10T428/31909; Y10T428/31913; Y10T428/31938
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
171 words
A biaxially stretched, composite polypropylene film suitable for use as an electrical insulating film, comprising a first layer comprising a first propylene polymer and having a maximum roughness height R z of its exposed surface of about 0.15 μm, and a second layer contiguous to said first layer comprising a second propylene polymer having a composition different from said first propylene polymer and having a roughness height R z on its exposed surface ranging between about 0.2 μm and 0.4 μm, said composite film being biaxially stretched and having a modulus of elasticity of at least about 2000 N/mm 2 in all directions of the plane of the film and a DC dielectric strength of at least about 650 V/μm, said composite film having been produced by the steps consisting essentially of joining said first and second layers together and subjecting the resulting composite film to biaxial stretching, and wherein the differences in said first and second propylene polymers are sufficient to produce said different roughness heights during said biaxial stretching.
Claim 2
Dependent Claim
171 words
A biaxially stretched, composite polypropylene film suitable for use as an electrical insulating film, comprising a first layer comprising a first propylene polymer and having a maximum roughness height R z of its exposed surface of about 0.15 μm, and a second layer contiguous to said first layer comprising a second propylene polymer having a composition different from said first propylene polymer and having a roughness height R z on its exposed surface ranging between about 0.2 μm and 0.4 μm, said composite film being biaxially stretched and having a modulus of elasticity of at least about 2000 N/mm 2 in all directions of the plane of the film and a DC dielectric strength of at least about 650 V/μm, said composite film having been produced by the steps consisting essentially of joining said first and second layers together and subjecting the resulting composite film to biaxial stretching, and wherein the differences in said first and second propylene polymers are sufficient to produce said different roughness heights during said biaxial stretching.
Claim 3
Dependent Claim
23 words
A film according to claim 1, wherein said first layer comprises more than about 50% of the total thickness of the composite film.
Claim 4
Dependent Claim
18 words
A film according to claim 1 or claim 2, wherein said second layer comprises a propylene block copolymer.
Claim 5
Dependent Claim
26 words
A film according to claim 1 or claim 2, wherein said second layer comprises a mixture of a propylene polymer with at least one other polymer.
Claim 6
Dependent Claim
39 words
A film according to claim 4, wherein said polymer mixture comprises from about 80 to 99% by weight of polypropylene and from about 20 to 1% by weight of polystyrene, polymethyl methacrylate or high density or low density polyethylene.
Claim 7
Dependent Claim
34 words
A film according to claim 3, wherein said block copolymer comprises from about 80 to 99% by weight of propylene and from about 20 to 1% by weight of styrene, methyl methacrylate or ethylene.
Claim 8
Dependent Claim
18 words
A film according to claim 1, further comprising a layer of metal on one of its exposed surfaces.
Claim 9
Dependent Claim
30 words
A film according to claim 7, wherein said metal layer has a thickness ranging from about 20 nm to 50 nm and a resistivity of from about 1 to 5Ω/□.
Claim 10
Dependent Claim
21 words
A film according to claim 8, wherein said metal layer is on the exposed surface of said first propylene polymer layer.
Claim 11
Dependent Claim
11 words
A film according to claim 9, wherein said metal comprises aluminum.
Claim 12
Dependent Claim
18 words
A capacitor, comprising a plurality of composite polypropylene films as defined by claim 7 laminated with one another.
Claim 13
Dependent Claim
36 words
A film according to claim 1, wherein said biaxial stretching comprises longitudinal stretching at a stretching ratio of between about 4 and 7 and transverse stretching at a stretching ratio of between about 7 and 11.
Claim 14
Dependent Claim
36 words
A film according to claim 12, wherein said biaxial stretching comprises longitudinal stretching at a stretching ratio of between about 4.5 and 6 and transverse stretching at a stretching ratio of between about 8 and 10.
Claim 15
Dependent Claim
40 words
A film according to claim 12, wherein said longitudinal stretching is carried out at a temperature between about 125° C. and 160° C. and said transverse stretching is carried out at a temperature between about 145° C. and 175° C.
Claim 16
Dependent Claim
28 words
A film according to claim 14, wherein said biaxially stretched film is heat set at a temperature between about 140° C. and 170° C. after said biaxially stretching.
Claim 17
Dependent Claim
20 words
A film according to claim 5, wherein said second polypropylene polymer comprises a blend of polypropylene and low density polyethylene.
Claim 18
Dependent Claim
19 words
A film according to claim 16, wherein said blend contains between about 3% and 9% of low density polyethylene.
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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) | 1984-08-10 | 1985-02-09 | 1985-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-10 | 1989-02-09 | 1989-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-10 | 1993-02-09 | 1993-08-11 | $7700.00 | Window Closed / Lapsed |