Patent US3686637A successfully refreshed from Google Patents.
US4074012A
Expired / Lapsed
US
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Fine-metal-particle-based magnetic recording medium of improved environmental stability
Assignee: 3M Co
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Filing: 1975-08-29
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Granted: 1978-02-14
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Expires: 1995-08-29
Abstract
Abstract Magnetic recording media having a magnetizable layer that comprises fine metal particles based on iron, cobalt, or nickel dispersed in a nonmagnetizable binder material have improved environmental stability because of the presence in the magnetizable layer of an organic compound that bears sterically unhindered aliphatic amine functionality.
Inventors
- 👤 Duane G. Heikkinen
- 👤 Thomas M. Kanten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:30
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7028; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/31504; Y10T428/31511; Y10T428/31529; Y10T428/31551; Y10T428/31565; Y10T428/31609; Y10T428/31678; Y10T428/31692; Y10T428/31699
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
130 words
Magnetic recording medium comprising a magnetizable layer carried on a nonmagnetizable support, the magnetizable layer comprising (a) a nonmagnetizable organic polymeric binder material; (b) fine magnetizable particles that comprise at least 75 weight-percent metal, at least a majority of which is iron, cobalt, or nickel, uniformly and thoroughly dispersed in the binder material; and (c) an organic compound having a molecular weight of less than 500 and providing, per gram of particles, at least 0.0001 gram-equivalent of sterically unhinered aliphatic tertiay amine which is located in terminal groups on the organic compound, is not reacted with said binder material and has a pK a of at least 8 when measured in an aqueous solution at 25° C, whereby the recording medium exhibits improved resistance to corrosion of said magnetizable particles.
Claim 2
Dependent Claim
130 words
Magnetic recording medium comprising a magnetizable layer carried on a nonmagnetizable support, the magnetizable layer comprising (a) a nonmagnetizable organic polymeric binder material; (b) fine magnetizable particles that comprise at least 75 weight-percent metal, at least a majority of which is iron, cobalt, or nickel, uniformly and thoroughly dispersed in the binder material; and (c) an organic compound having a molecular weight of less than 500 and providing, per gram of particles, at least 0.0001 gram-equivalent of sterically unhinered aliphatic tertiay amine which is located in terminal groups on the organic compound, is not reacted with said binder material and has a pK a of at least 8 when measured in an aqueous solution at 25° C, whereby the recording medium exhibits improved resistance to corrosion of said magnetizable particles.
Claim 3
Dependent Claim
14 words
Magnetic recording medium of claim 1 in which the binder material comprises a polyurethane.
Claim 4
Dependent Claim
23 words
Magnetic recording medium of claim 1 in which the magnetizable layer further includes an acidic organic surfactant for assisting to disperse the particles.
Claim 5
Dependent Claim
26 words
Magnetic recording medium of claim 1 in which the particles carry a chromium-based outer layer formed prior to dispersion of the particles in the binder material.
Claim 6
Dependent Claim
16 words
Magnetic recording medium of claim 1 in which the aliphatic-amine-bearing oganic compound comprises tris-2,4,6-(dimethyl-amino methyl) phenol.
Claim 7
Dependent Claim
18 words
Magnetic recording medium of claim 1 which the particles constitute at least 70 weight-percent of the magnetizable layer.
Claim 8
Dependent Claim
46 words
Magnetic recording medium of claim 1 in which the aliphatic-amine-bearing organic compound is included in an amount providing, per gram of particles, at least 0.0003 gram-equivalent of sterically unhindered aliphatic amine having a pK a of at least 8 in an aqueous soluton at 25° C.
Claim 9
Dependent Claim
27 words
Magnetic recording medium of claim 1 in which said organic compound is included in an amount of less than 0.07 gram/gram of particles included in the medium.
Claim 10
Dependent Claim
20 words
Magnetic recording medium of claim 1 in which at least 75 weight-percent of the metal in said particles is iron.
Claim 11
Dependent Claim
15 words
Magnetic recording medium of claim 8 in which said particles carry a chromium-based outer layer.
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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) | 1981-02-13 | 1981-08-15 | 1982-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-13 | 1985-08-15 | 1986-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-13 | 1989-08-15 | 1990-02-14 | $7700.00 | Window Closed / Lapsed |