US4865898A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polyester film for magnetic recording media
Assignee: Mitsubishi Chemical Corp
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Filing: 1987-08-12
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Granted: 1989-09-12
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Expires: 2007-08-12
Abstract
Abstract Disclosed herein is a biaxially oriented polyester film for magnetic recording media, containing uniformly carbon black particles and having the following specific properties: T900 </= 50% (1) 0.003 mu m </= Ra </= 0.025 mu m (2) <IMAGE> (3) n2 </= 10 (4) wherein T900 represents a light transmittance of the film at a wavelength of 900 nm, Ra represents an average surface roughness of the film n1 represents the number of protuberances of 0.81 to 1.08 mu m in height existing on the surface of the film per film area of 25 cm2, and n2 represents the number of protuberances of more than 1.08 mu m in height existing on the surface of the film per film area of 25 cm2.
Inventors
- 👤 Yujiro Fukuda
- 👤 Shigeo Utsumi
- 👤 Kichinojyo Tomitaka
- 👤 Toshifumi Takisawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:15
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; G11B5/73935; G11B5/84; G11B5/8404; Y; Y02; Y02P; Y02P20/00; Y02P20/50; Y02P20/582; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24372; Y10T428/25; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
116 words
A biaxially oriented polyester film for magnetic recording media, containing uniformly dispersed carbon black particles of an average particle diameter of 10 to 30 mm and having the following specific properties: ##EQU8## wherein T 900 represents the light transmittance of the film at a wavelength of 900 nm, Ra represents an average surface roughness of the film, n 1 represents the number of protuberance of 0.81 to 1.08 μm in height existing on the surface of the film per film area of 25 cm 2 , and n 2 represents the number of protuberance of more than 1.08 μm in height existing on the surface of the film per film area of 25 cm 2 .
Claim 2
Dependent Claim
116 words
A biaxially oriented polyester film for magnetic recording media, containing uniformly dispersed carbon black particles of an average particle diameter of 10 to 30 mm and having the following specific properties: ##EQU8## wherein T 900 represents the light transmittance of the film at a wavelength of 900 nm, Ra represents an average surface roughness of the film, n 1 represents the number of protuberance of 0.81 to 1.08 μm in height existing on the surface of the film per film area of 25 cm 2 , and n 2 represents the number of protuberance of more than 1.08 μm in height existing on the surface of the film per film area of 25 cm 2 .
Claim 3
Dependent Claim
24 words
A biaxially oriented polyester film for magnetic recording media according to claim 1, further containing inert inorganic particles other than the carbon black particles.
Claim 4
Dependent Claim
28 words
A biaxially oriented polyester film for magnetic recording media according to claim 2, wherein said inert inorganic particles other than the carbon black particles are titanium oxide particles.
Claim 5
Dependent Claim
20 words
A biaxially oriented polyester film for magnetic recording media according to claim 1, wherein Ra is 0.005 to 0.02 μm.
Claim 6
Dependent Claim
21 words
A biaxially oriented polyester film for magnetic recording media according to claim 1, wherein n 2 is not more than 5.
Claim 7
Dependent Claim
25 words
A biaxially oriented polyester film for magnetic recording media according to claim 1, wherein said intrinsic viscosity (η) of the film is 0.45 to 0.70.
Claim 8
Dependent Claim
39 words
A biaxially oriented polyester film for magnetic recording media according to claim 1, wherein the sum of F 5 values in the machine direction and the transverse direction of the film is not less than 15 kg/cm 2 .
Claim 9
Dependent Claim
26 words
A biaxially oriented polyester film for magnetic recording media according to claim 1, wherein the content of said carbon black is 0.05 to 5 wt %.
Claim 10
Dependent Claim
28 words
A biaxially oriented polyester film for magnetic recording media according to claim 2, wherein the average particle diameter of said inert inorganic particles is 0.05 to 5 μm.
Claim 11
Dependent Claim
28 words
A biaxially oriented polyester film for magnetic recording media according to claim 3, wherein the average particle diameter of said titanium oxide particles is 0.05 to 3 μm.
Claim 12
Dependent Claim
29 words
A biaxially oriented polyester film for magnetic recording media according to claim 1, wherein n 1 is not more than the lesser of 40 log 80/T 900 and 60.
References Cited (Backward Citations)
FR2242417A1
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JPS58168526A
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JPS5971357A
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US4680217A
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JPH05152808A
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JPH05330447A
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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) | 1992-09-11 | 1993-03-13 | 1993-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-11 | 1997-03-13 | 1997-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-11 | 2001-03-13 | 2001-09-12 | $7700.00 | Window Closed / Lapsed |