US4824587A
Expired / Lapsed
US
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Composites of coercive particles and superparamagnetic particles
Assignee: Dow Chemical Co
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Filing: 1985-03-18
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Granted: 1989-04-25
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Expires: 2005-03-18
Abstract
Abstract Composites of coercive particles and superparamagnetic particles comprise an intimate admixture of said particles in a dielectric matrix. The particles are admixed in such a fashion as to provide a composite which exhibits a coercivity which behaves as if the coercive particles and the superparamagnetic particles interact. Composites exhibiting such controlled coercivity are useful in the manufacture of transformers, magnets and magnetic tapes.
Inventors
- 👤 O'Dae Kwon
- 👤 Jitka Solc
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:18
CPC Classifications
B; B82; B82Y; B82Y25/00; H; H01; H01F; H01F1/00; H01F1/0036; H01F1/0045; H01F1/0054; H01F1/0063; H01F1/01; H01F1/03; H01F1/12; H01F1/34; H01F1/36; H01F1/37; H01F1/44
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
50 words
A stable, fluid aqueous dispersion comprising a mixture of (1) coercive particles and (2) a magnetic latex of from about 5 to about 70 weight percent of superparamagnetic particles in a hydrophobic polymer matrix wherein the hydrophobic polymer matrix maintains the superparamagnetic particles in an essentially discrete, spaced apart relationship.
Claim 2
Dependent Claim
50 words
A stable, fluid aqueous dispersion comprising a mixture of (1) coercive particles and (2) a magnetic latex of from about 5 to about 70 weight percent of superparamagnetic particles in a hydrophobic polymer matrix wherein the hydrophobic polymer matrix maintains the superparamagnetic particles in an essentially discrete, spaced apart relationship.
Claim 3
Dependent Claim
12 words
A magnetic composite prepared by drying the aqueous dispersion of claim 1.
Claim 4
Dependent Claim
13 words
The composite of claim 2 in the form of a film or powder.
Claim 5
Dependent Claim
35 words
The composite of claim 2 wherein the coercive particles are of a size within a range such that said particles exhibit a coercivity great enough to exhibit interaction effects when combined with said superparamagnetic particles.
Claim 6
Dependent Claim
21 words
The composite of claim 2 wherein the coercive particles are of a size very nearly equal to the single domain stage.
Claim 7
Dependent Claim
23 words
The composite of claim 2 wherein the coercive particles exhibit a grain size which ranges from about 0.05 μm to about 25 μm.
Claim 8
Dependent Claim
33 words
The composite of claim 2 wherein the amount of coercive particles relative to the amount of superparamagnetic particles range from about 99:1 to about 50:50, based on the weights of said particle components.
Claim 9
Dependent Claim
43 words
The composite of claim 2 wherein the coercive particles are maintained in an essentially discrete spaced apart relationship in the dielectric material and wherein the superparamagnetic particles can behave as if such particles are uniformly dispersed so as to encapsulate the coercive particles.
Claim 10
Dependent Claim
18 words
The composite of claim 2 wherein said coercive particles are spinel ferrites, magnetoplumbite ferrites, garnets or ferromagnetic alloys.
Claim 11
Dependent Claim
18 words
The composite of claim 2 wherein said superparamagnetic particles are spinel ferrites, magnetoplumbite ferrites, garnets or ferromagnetic alloys.
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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) | 1992-04-24 | 1992-10-24 | 1993-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-24 | 1996-10-24 | 1997-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-24 | 2000-10-24 | 2001-04-25 | $7700.00 | Window Closed / Lapsed |