US4367511A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rough electrical insulating film of polypropylene and process for the manufacture thereof
Assignee: Hoechst AG
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Filing: 1980-10-10
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Granted: 1983-01-04
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Expires: 2000-10-10
Abstract
Abstract Disclosed is a film for use in the field of electrical insulation comprising a biaxially stretched rough polypropylene film comprising a plurality of first zones of high roughness, the first zones having a relatively high number of α-crystallites; and a plurality of second zones of substantially lesser roughness, the second zones having a substantially lesser number of α-crystallites than the first zones, the first zones being adjacent to the second zones and the adjacent first and second zones forming fine channels between each other. Also disclosed is a method for producing this film.
Inventors
- 👤 Gunther Crass
- 👤 Hartmut Hensel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:26
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; H; H01; H01B; H01B3/00; H01B3/18; H01B3/30; H01B3/44; H01B3/441; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/14; H01G4/18; H01G4/20; H01G4/22; B; B29; B29C; B29C48/00; B29C48/001; B29C48/0018; B29C48/03; B29C48/07; B29C48/08; B29K; B29K2995/00; B29K2995/0037; B29K2995/0072; C08J2323/00; C08J2323/02; C08J2323/10; C08J2323/12; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24479; Y10T428/24521; Y10T428/24537; Y10T428/24545; Y10T428/2457; Y10T428/31; Y10T428/31504; Y10T428/31678; Y10T428/31692
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
82 words
A film for use in the field of electrical insulation comprising a biaxially stretched rough polypropylene film comprising a plurality of first zones of high roughness, said first zones having a relatively high number of α-crystallites; and a plurality of second zones of substantially lesser roughness, said second zones having a substantially lesser number of α-crystallites than said first zones, said first zones being adjacent to said second zones and said adjacent first and second zones forming fine channels between each other.
Claim 2
Dependent Claim
82 words
A film for use in the field of electrical insulation comprising a biaxially stretched rough polypropylene film comprising a plurality of first zones of high roughness, said first zones having a relatively high number of α-crystallites; and a plurality of second zones of substantially lesser roughness, said second zones having a substantially lesser number of α-crystallites than said first zones, said first zones being adjacent to said second zones and said adjacent first and second zones forming fine channels between each other.
Claim 3
Dependent Claim
117 words
A film according to claim 1, produced by the process comprising the steps of: extruding a pre-film of polypropylene; cooling the extruded pre-film to a temperature which is sufficient to produce β-crystallites in the pre-film; generating a substantially higher number of β-crystallites in said first zone in comparison to said second zone by causing different temperatures in said first and said second zones; converting said β-crystallites to α-crystallites by stretching the pre-film both transversely and longitudinally at a temperature sufficient to produce α-crystallites in the resulting stretched film whereby said first zones having a relatively high number of α-crystallites and said second zones have a substantially lesser number of α-crystallites are produced; and heat setting the film.
Claim 4
Dependent Claim
44 words
The film according to claim 2, wherein said extruded pre-film is cooled on a take-up roll, and said step of causing different temperatures in first and second zones comprises differently cooling said first and second zones while the pre-film is on said take-up roll.
Claim 5
Dependent Claim
31 words
The film according to claim 2, wherein said step of causing different temperatures in said first and second zones comprises heating said first and second zones prior to said stretching step.
Claim 6
Dependent Claim
22 words
The film according to claim 2, wherein said stretching step comprises first longitudinally stretching said pre-film followed by transversely stretching said pre-film.
Claim 7
Dependent Claim
22 words
The film according to claim 2, wherein said stretching step comprises first transversely stretching said pre-film followed by longitudinally stretching said pre-film.
Claim 8
Dependent Claim
17 words
The film according to claim 2, further comprising the step of metallizing one side of said film.
Claim 9
Dependent Claim
18 words
The film according to claim 2, further comprising the step of re-stretching said film prior to heat setting.
Claim 10
Dependent Claim
63 words
The film according to claim 5, wherein said stretching step is carried out between about 120° C. and 160° C., the ratio of longitudinal stretching is from about 1:4 to 1:6.5, the ratio of transverse stretching is from about 1:8 to 1:12 and wherein the biaxially stretched film is then heat set at a temperature of from about 150° C. to 180° C.
Claim 11
Dependent Claim
77 words
The film according to claim 1, wherein both sides of said film comprise a plurality of first zones of high roughness, said first zones have a relatively high number of α-crystallites; and a plurality of second zones of substantially less roughness, said second zones having a substantially lesser number of α-crystallites than said first zones, said first zones being adjacent to said second zones and said adjacent first and second zones forming fine channels between each other.
Claim 12
Dependent Claim
20 words
The film according to claim 9, wherein said stretching step is carried out between about 135° C. and 150° C.
Claim 13
Dependent Claim
21 words
The film according to claim 1, wherein said first and second zones are regularly distributed, over the surface of the film.
Claim 14
Dependent Claim
28 words
A film according to claim 1, wherein the degree of roughness of the higher-roughness zones and the lower-roughness zones differ by a factor of about 1.5 to 5.0.
Claim 15
Dependent Claim
17 words
A film according to claim 1, wherein the size of said zones is ≧0.1 mm 2 .
Claim 16
Dependent Claim
16 words
A film according to claim 1, wherein the higher-roughness zones predominate as against the lower-roughness zones.
Claim 17
Dependent Claim
35 words
A film according to claim 1, wherein the mean roughness height R z ranges between 1.0 μm and 4.0 μm in the higher-roughness zones and between 0.1 μm and 1.0 μm in the lower-roughness zones.
Claim 18
Dependent Claim
24 words
A film according to claim 1, wherein said fine channels run in the transverse direction with respect to the longitudinal axis of the film.
Claim 19
Dependent Claim
15 words
A film according to claim 1, further comprising a layer of metal on one surface.
Claim 20
Dependent Claim
26 words
A capacitor, comprising alternating layers of a dielectric material and a metallic conductive material, wherein the dielectric material comprises the film as defined by claim 1.
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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) | 1986-01-03 | 1986-07-05 | 1987-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-03 | 1990-07-05 | 1991-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-03 | 1994-07-05 | 1995-01-04 | $7700.00 | Window Closed / Lapsed |