US4379803A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
•
Filing: 1981-09-29
•
Granted: 1983-04-12
•
Expires: 2001-09-29
Abstract
Abstract A magnetic recording medium having a substrate coated with a magnetic layer comprises a binder, a magnetic powder and a metal phosphide at a ratio of 0.2 to 5.0 wt. % based on said magnetic powder.
Inventors
- 👤 Kiminori Tamai
- 👤 Masashi Hayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:06
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; G11B5/706; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/259
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
53 words
A magnetic recording medium, comprising: a substrate coated with a magnetic layer, said magnetic layer comprising a synthetic binder, a magnetic powder and at least one Group VIII metal phosphide with the amount of said metal phosphide in said magnetic layer ranging from 0.2 to 5.0 wt. % based on said magnetic powder.
Claim 2
Dependent Claim
53 words
A magnetic recording medium, comprising: a substrate coated with a magnetic layer, said magnetic layer comprising a synthetic binder, a magnetic powder and at least one Group VIII metal phosphide with the amount of said metal phosphide in said magnetic layer ranging from 0.2 to 5.0 wt. % based on said magnetic powder.
Claim 3
Dependent Claim
16 words
The magnetic recording medium of claim 1, wherein said magnetic layer further comprises a particulate abrasive.
Claim 4
Dependent Claim
50 words
The magnetic recording medium of claim 2, wherein said particulate abrasive has a Mohs' hardness of at least 6, an average particle size of no more than 3 μm, and is present in said layer in an amount of no more than 0.5 wt. % based on said magnetic powder.
Claim 5
Dependent Claim
22 words
The magnetic recording medium of claim 2, wherein said particulate abrasive is chromium oxide, alumina, silicon carbide, titanium dioxide or silicon dioxide.
Claim 6
Dependent Claim
19 words
The magnetic recording medium of claim 1, wherein said metal phosphide is nickel phosphide, cobalt phosphide or iron phosphide.
Claim 7
Dependent Claim
17 words
The magnetic recording medium of claim 1, wherein said magnetic powder is γ-Fe 2 O 3 .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-04-11 | 1986-10-11 | 1987-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-04-11 | 1990-10-11 | 1991-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-04-11 | 1994-10-11 | 1995-04-12 | $7700.00 | Window Closed / Lapsed |