US4399189A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
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Filing: 1981-12-11
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Granted: 1983-08-16
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Expires: 2001-12-11
Abstract
Abstract A magnetic recording medium comprises a substrate coated with a magnetic layer comprising a magnetic powder and a first non-magnetic powder of Al 2 O 3 and/or Cr 2 O 3 at a ratio of 0.5 to 15 wt. % based on said magnetic powder; a second non-magnetic powder of TiO 2 , SiC, SiO 2 , ZrO 2 and/or CeO 2 at a ratio of 0.5 to 15 wt. % based on said magnetic powder and a total of said non-magnetic powders of less than 20 wt. % based on said magnetic powder.
Inventors
- 👤 Yutaka Nakashima
- 👤 Akira Okada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:03
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
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
148 words
The method of improving the still characteristic of a magnetic tape without undesirably increasing the wearing of the head of a recorder, comprising: applying to a tape substrate a magnetic layer comprising a mixture of a magnetic powder in a synthetic resin binder and a non-magnetic powder component consisting essentially of a first non-magnetic powder of Al 2 O 3 , Cr 2 O 3 or mixtures thereof and a second non-magnetic powder of TiO 2 , SiC, SiO 2 , ZrO 2 , CeO 2 or mixtures thereof, both of said non-magnetic powders being present in said magnetic layer in an amount ranging from 0.5 to 15 weight % with the total of said non-magnetic powders being less than 20 weight % based on the magnetic powder, wherein the average particle diameter of said first and second non-magnetic powders is in the range of 0.1 to 2μ.
Claim 2
Independent Claim
148 words
The method of improving the still characteristic of a magnetic tape without undesirably increasing the wearing of the head of a recorder, comprising: applying to a tape substrate a magnetic layer comprising a mixture of a magnetic powder in a synthetic resin binder and a non-magnetic powder component consisting essentially of a first non-magnetic powder of Al 2 O 3 , Cr 2 O 3 or mixtures thereof and a second non-magnetic powder of TiO 2 , SiC, SiO 2 , ZrO 2 , CeO 2 or mixtures thereof, both of said non-magnetic powders being present in said magnetic layer in an amount ranging from 0.5 to 15 weight % with the total of said non-magnetic powders being less than 20 weight % based on the magnetic powder, wherein the average particle diameter of said first and second non-magnetic powders is in the range of 0.1 to 2μ.
Claim 3
Dependent Claim
49 words
The method of claim 1, wherein the amount of said first non-magnetic powder is in a range of 1 to 15 wt% based on the magnetic powder and the amount of said second nonmagnetic powder is in a range of 1 to 15 wt% based on said magnetic powder.
Claim 4
Independent Claim
40 words
The method of claims 1 or 2, wherein said magnetic powder is powdered Co-adsorbed on iron oxide, γ-Fe 2 O 3 , Fe 3 O 4 , Co-adsorbed on Fe 3 O 4 , ferromagnetic alloy or a mixture thereof.
Claim 5
Dependent Claim
24 words
The method of claim 1, wherein said first nonmagnetic powder is Al 2 O 3 and said second non-magnetic powder is TiO 2 .
References Cited (Backward Citations)
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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) | 1986-08-15 | 1987-02-14 | 1987-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-15 | 1991-02-14 | 1991-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-15 | 1995-02-14 | 1995-08-16 | $7700.00 | Window Closed / Lapsed |