US4990276A
Expired / Lapsed
US
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Magnetic dispersion
Assignee: Eastman Kodak Co
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Filing: 1990-02-01
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Granted: 1991-02-05
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Expires: 2010-02-01
Abstract
Abstract A dispersion consisting essentially of magnetic particles, a dialkylester of phthalic acid which functions as a dispersing medium, and optionally, a dispersing agent is particularly useful as a precursor to a composition suitable for casting onto a cellulose acid ester support film to form a transparent magnetic recording layer for use in photographic films. The dispersion provides magnetic recording layers exhibiting fewer particle agglomerations and reduced light scattering and photographic prints prepared from films containing such magnetic layers exhibit virtually no increase in graininess attributable to the magnetic recording layer.
Inventors
- 👤 John F. Bishop
- 👤 Robert O. James
- 👤 Diane E. Kestner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:26
CPC Classifications
H; H01; H01F; H01F41/00; H01F41/14; H01F41/16; G; G11; G11B; G11B5/00; G11B5/62; G11B5/633; G11B5/68; G11B5/70; G11B5/7013
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
47 words
A dispersion consisting essentially of magnetic particles, a dialkylester of phthalic acid, and a dispersing agent "said dialkylester being present in the amount of between 25 and 75% by weight and said dispersing agent being present up to 10% by weight with the balance being magnetic particles."
Claim 2
Dependent Claim
47 words
A dispersion consisting essentially of magnetic particles, a dialkylester of phthalic acid, and a dispersing agent "said dialkylester being present in the amount of between 25 and 75% by weight and said dispersing agent being present up to 10% by weight with the balance being magnetic particles."
Claim 3
Dependent Claim
19 words
The dispersion of claim 1, wherein the alkyl portion of said dialkylester contains from 4 to 8 carbon atoms.
Claim 4
Dependent Claim
10 words
The dispersion of claim 1, wherein said ester is dibutylphthalate.
Claim 5
Dependent Claim
19 words
The dispersion of claim 1, wherein said magnetic particles consist of cobalt surface treated γ-Fe 2 O 2 particles.
Claim 6
Dependent Claim
19 words
The dispersion of claim 1, wherein said magnetic particles have an average length of less than about 0.3 micron.
Claim 7
Dependent Claim
14 words
The dispersion of claim 1, wherein said dispersing agent is a phosphoric acid ester.
Claim 8
Dependent Claim
34 words
The dispersion consisting essentially of magnetic particles and a dialkyl ester of phthalic acid "said dialkylester being present in the amount of between 25 and 75% by weight and the balance being magnetic particles".
Claim 9
Dependent Claim
34 words
The dispersion consisting essentially of magnetic particles and a dialkyl ester of phthalic acid "said dialkylester being present in the amount of between 25 and 75% by weight and the balance being magnetic particles".
References Cited (Backward Citations)
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US3653962A
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US3634137A
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US3767464A
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US3782947A
Cited
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Cited
US4677030A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-04 | 1994-08-06 | 1995-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-04 | 1998-08-06 | 1999-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-04 | 2002-08-06 | 2003-02-05 | $7700.00 | Window Closed / Lapsed |