US4618536A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Maxell Ltd
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Filing: 1984-09-04
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Granted: 1986-10-21
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Expires: 2004-09-04
Abstract
Abstract A magnetic recording medium having a high durability with good electro-magnetic properties, which comprises a base material and a magnetic layer provided thereon, the magnetic layer containing magnetic particles and a binder, characterized in that the magnetic layer further comprises alpha-Fe2O3 particles, Al2O3 particles and Cr2O3 particles.
Inventors
- 👤 Akira Morioka
- 👤 Takeshi Matsuura
- 👤 Yoshiyuki Takahira
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:46
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G02; G02B; G02B6/00; G02B6/44; G02B6/4401; G02B6/4415; G02B6/4427; G02B6/4428; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/2419; Y10T428/24215; Y10T428/24231; Y10T428/2424; Y10T428/24248; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
134 words
An abrasion resistant magnetic recording medium comprising a base material and a magnetic layer provided thereon, said magnetic layer containing magnetic particles, a binder, and a mixture of abrasion resistant particles consisting essentially of alpha-Fe 2 O 3 particles having an average particle size of from 0.4 to 2.0 microns in an amount of from 2 to 10% by weight to the weight of the magnetic particles, Al 2 O 3 particles having an average particle size of from 0.2 to 0.7 micron in an amount of from 2 to 4% by weight to the weight of the magnetic particles and Cr 2 O 3 particles having an average particle size of from 0.4 to 1.5 microns in an amount of from 0.2 to 1.0% by weight to the weight of the magnetic particles.
Claim 2
Dependent Claim
134 words
An abrasion resistant magnetic recording medium comprising a base material and a magnetic layer provided thereon, said magnetic layer containing magnetic particles, a binder, and a mixture of abrasion resistant particles consisting essentially of alpha-Fe 2 O 3 particles having an average particle size of from 0.4 to 2.0 microns in an amount of from 2 to 10% by weight to the weight of the magnetic particles, Al 2 O 3 particles having an average particle size of from 0.2 to 0.7 micron in an amount of from 2 to 4% by weight to the weight of the magnetic particles and Cr 2 O 3 particles having an average particle size of from 0.4 to 1.5 microns in an amount of from 0.2 to 1.0% by weight to the weight of the magnetic particles.
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) | 1989-10-20 | 1990-04-21 | 1990-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-20 | 1994-04-21 | 1994-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-20 | 1998-04-21 | 1998-10-21 | $7700.00 | Window Closed / Lapsed |