US4234438A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
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Filing: 1979-05-10
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Granted: 1980-11-18
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Expires: 1999-05-10
Abstract
Abstract A magnetic recording medium comprises a substrate coated with a magnetic coating composition comprising nitrocellulose impregnated with a vinyl chloride-vinyl acetate-vinyl alcohol copolymer having a content of vinyl alcohol component of 8 wt. % or more, a magnetic powder, a solvent, and a thermal crosslinking agent.
Inventors
- 👤 Eiji Horigome
- 👤 Hiroshi Ota
- 👤 Hitoshi Azegami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:42
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7023; C; C08; C08G; C08G18/00; C08G18/06; C08G18/28; C08G18/40; C08G18/62; C08G18/6212; C08L; C08L75/00; C08L75/04; G11B5/7021; G11B5/7022
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
66 words
A magnetic recording medium useful as a magnetic coating composition prepared by a process, comprising: removing alcohol from an alcohol impregnated nitrocellulose composition; impregnating said alcohol free nitrocellulose with a vinyl chloride-vinylacetate-vinylalcohol copolymer having a vinyl alcohol content of at least 8 wt.%; blending a magnetic powder, a cross-linkable polymer and a solvent with the impregnated nitrocellulose; and adding a cross-linking agent to said blended mixture.
Claim 2
Dependent Claim
66 words
A magnetic recording medium useful as a magnetic coating composition prepared by a process, comprising: removing alcohol from an alcohol impregnated nitrocellulose composition; impregnating said alcohol free nitrocellulose with a vinyl chloride-vinylacetate-vinylalcohol copolymer having a vinyl alcohol content of at least 8 wt.%; blending a magnetic powder, a cross-linkable polymer and a solvent with the impregnated nitrocellulose; and adding a cross-linking agent to said blended mixture.
Claim 3
Dependent Claim
14 words
The magnetic recording medium of claim 1, wherein said cross-linkable polymer is a polyurethane.
Claim 4
Dependent Claim
14 words
The magnetic recording medium of claim 1, wherein said cross-linkable polymer is a polyester.
Claim 5
Dependent Claim
17 words
The magnetic recording medium of claims 1, 2 or 3 wherein said cross-linking agent is a polyisocyanate.
Claim 6
Dependent Claim
26 words
The magnetic recording medium of claim 1, wherein the content of said vinylalcohol component in said copolymer is in the range of 8 to 30 wt.%.
Claim 7
Dependent Claim
29 words
The magnetic recording medium of claim 1, wherein the weight ratio of nitrocellulose to the mixture of nitrocellulose and said copolymer is in the range of 0.05 to 0.8.
References Cited (Backward Citations)
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Cited
US3810840A
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US4066564A
Cited
US4020236A
Cited
US4135031A
Cited
US4152485A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-11-18 | 1984-05-19 | 1984-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-18 | 1988-05-19 | 1988-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-18 | 1992-05-19 | 1992-11-18 | $7700.00 | Window Closed / Lapsed |