US4533582A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stabilized magnetic recording materials and process for tailoring and stabilizing of magnetic recording materials
Assignee: International Business Machines Corp
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Filing: 1983-07-19
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Granted: 1985-08-06
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Expires: 2003-07-19
Abstract
Abstract A storage stable, pre-selected magnetic coercivity is imparted to a recording disk having a film of heat curable magnetic coating composition thereon by curing the composition in an anaerobic atmosphere at a high temperature, and then heating, typically in air, at a lower temperature for a period of time effective to raise the coercivity to the pre-selected higher value.
Inventors
- 👤 Vincent M. DePalma
- 👤 Albert W. Ward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:48
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/74; G11B5/82; G11B5/84; G11B5/842; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31511; Y10T428/31551; Y10T428/31609; Y10T428/31678
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
159 words
A method of imparting a storage stable preselected magnetic coercivity value to a film of a magnetic coating composition on a substrate and including a heat curable binder system having magnetic particles therein, comprising the steps of: curing said coating composition in an anaerobic atmosphere by heating said film at a temperature and for a period of time effective to cure the binder system and raise the magnetic coercivity of said coating composition to a first, storage unstable value lower than said preselected value but substantially higher than the value achievable when said coating composition is cured in air; annealing said cured composition by heating said cured coating composition at a temperature substantially lower than said curing temperature, but higher than standard room temperature, for a period of time effective to further increase the coercivity of said coating composition to the selected value; and cooling said coating composition thereby rendering its magnetic coercivity storage stable at said pre-selected value.
Claim 2
Independent Claim
159 words
A method of imparting a storage stable preselected magnetic coercivity value to a film of a magnetic coating composition on a substrate and including a heat curable binder system having magnetic particles therein, comprising the steps of: curing said coating composition in an anaerobic atmosphere by heating said film at a temperature and for a period of time effective to cure the binder system and raise the magnetic coercivity of said coating composition to a first, storage unstable value lower than said preselected value but substantially higher than the value achievable when said coating composition is cured in air; annealing said cured composition by heating said cured coating composition at a temperature substantially lower than said curing temperature, but higher than standard room temperature, for a period of time effective to further increase the coercivity of said coating composition to the selected value; and cooling said coating composition thereby rendering its magnetic coercivity storage stable at said pre-selected value.
Claim 3
Dependent Claim
25 words
A method as in claim 1 wherein said curing step is conducted at a temperature of about 175° C.-290° C. for at least 1 hour.
Claim 4
Dependent Claim
21 words
A method as in claim 1, wherein said annealing step is conducted at a temperature of up to about 120° C.
Claim 5
Dependent Claim
37 words
A method as in claim 1 wherein said curing step is conducted at a temperature of at least about 220° C. and said annealing step is conducted at a temperature between about 60° C. and 90° C.
Claim 6
Dependent Claim
33 words
A method as in claim 1 wherein in said curing step the coercivity of said composition is raised to about the maximum value possible by curing said coating composition in an anaerobic atmosphere
Claim 7
Dependent Claim
14 words
A method as in claim 1 wherein the annealing step is conducted in air.
Claim 8
Dependent Claim
57 words
A method as in claim 1 wherein the curable binder is an epoxy/phenolic resin, the magnetic particles are γ-Fe 2 O 3 particles, the curing is conducted for about 2 hours at a temperature of at least about 220° C., and the annealing step is conducted at a temperature of about 60° C. to about 90° C.
Claim 9
Dependent Claim
60 words
A method as in claim 1 wherein the curable binder is an epoxy/phenolic resin, the magnetic particles are cobalt-adsorbed 65 -Fe 2 O 3 particles, the curing step is conducted for about 2 hours at a temperature of at least about 220° C., and the annealing step is conducted at a temperature of about 60° C. to about 90° C.
Claim 10
Dependent Claim
58 words
A method as in claim 1 wherein the curable binder is a polyurethane resin, the magnetic particles are cobalt-adsorbed γ-Fe 2 O 3 particles, the curing step is conducted for about 2 hours at a temperature of at least about 200° C., and the annealing step is conducted at a temperature of about 60° C. to 90° C.
Claim 11
Dependent Claim
21 words
A magnetic recording disk comprising a film of a cured magnetic coating composition produced according to the process of claim 1.
Claim 12
Dependent Claim
23 words
A recording disk as in claim 10 wherein said coating composition is γ-Fe 2 O 3 particles dispersed in a cured epoxy/phenolic binder.
Claim 13
Dependent Claim
24 words
A recording disk as in claim 10 wherein said coating composition is cobalt adsorbed-γ-Fe 2 O 3 particles dispersed in a cured epoxy/phenolic binder.
Claim 14
Dependent Claim
22 words
A recording disk as in claim 10 wherein said coating composition is cobalt-adsorbed-γ-Fe 2 O 3 particles in a cured polyurethane resin.
Claim 15
Dependent Claim
32 words
A recording disk as in claim 10 comprising two magnetic recording layers, a first layer comprising a buried servo layer of enhanced stable coercivity, and a second layer of lower stable coercivity.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-08-05 | 1989-02-04 | 1989-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-05 | 1993-02-04 | 1993-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-05 | 1997-02-04 | 1997-08-06 | $7700.00 | Window Closed / Lapsed |