US4668568A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1986-06-20
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Granted: 1987-05-26
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Expires: 2006-06-20
Abstract
Abstract This invention provide a magnetic recording medium with well-balanced excellent properties as to video head abrasion, still life, video S/N and drop out, which comprises a non-magnetic support and a magnetic recording layer containing a ferromagnetic powder, a binder and (A) at least one inorganic compound powder selected from the group consisting of Cr 2 O 3 , SiC and mixtures thereof and (B) at least one inorganic compound powder selected from the group consisting of Al 2 O 3 , TiO 2 , SiO 2 , ZnO and mixtures thereof.
Inventors
- 👤 Masaaki Fujiyama
- 👤 Nobuo Tsuji
- 👤 Nobutaka Yamaguichi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:16
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/259; Y10T428/31504; Y10T428/31551; Y10T428/31609; Y10T428/31971
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
167 words
A magnetic recording medium comprising a non-magnetic support and a magnetic recording layer containing a ferromagnetic powder, a binder and (A) 0.1 to 0.4% by weight based on the weight of the ferromagnetic powder of at least one inorganic powder selected from the group consisting of Cr 2 O 3 , SiC and mixtures thereof and (B) at least 3.0% by weight based on the weight of the ferromagnetic powder of at least one inorganic powder selected from the group consisting of Al 2 O 3 , TiO 2 , SiO 2 , and ZnO and mixtures thereof; the inorganic powder (A) having a particle size of 0.2 to 5 microns and a Mohs' hardness of 8.5 to 9.5, the inorganic powder (B) having a particle size of at most 1 micron and smaller than that of the inorganic powder (A) and a Mohs' hardness smaller than that of the inorganic powder (A), and the binder consisting of a nitrocellulose resin, a urethane resin and a polyisocyanate.
Claim 2
Dependent Claim
167 words
A magnetic recording medium comprising a non-magnetic support and a magnetic recording layer containing a ferromagnetic powder, a binder and (A) 0.1 to 0.4% by weight based on the weight of the ferromagnetic powder of at least one inorganic powder selected from the group consisting of Cr 2 O 3 , SiC and mixtures thereof and (B) at least 3.0% by weight based on the weight of the ferromagnetic powder of at least one inorganic powder selected from the group consisting of Al 2 O 3 , TiO 2 , SiO 2 , and ZnO and mixtures thereof; the inorganic powder (A) having a particle size of 0.2 to 5 microns and a Mohs' hardness of 8.5 to 9.5, the inorganic powder (B) having a particle size of at most 1 micron and smaller than that of the inorganic powder (A) and a Mohs' hardness smaller than that of the inorganic powder (A), and the binder consisting of a nitrocellulose resin, a urethane resin and a polyisocyanate.
Claim 3
Dependent Claim
29 words
The magnetic recording medium of claim 1, wherein the quantity of the inorganic powder (B) is at least 10 times as much as that of the inorganic powder (A).
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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) | 1990-05-25 | 1990-11-24 | 1991-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-25 | 1994-11-24 | 1995-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-25 | 1998-11-24 | 1999-05-26 | $7700.00 | Window Closed / Lapsed |