US4430239A
Expired / Lapsed
US
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Ferrofluid composition and method of making and using same
Assignee: Ferrofluidics Corp
•
Filing: 1983-02-07
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Granted: 1984-02-07
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Expires: 2003-02-07
Abstract
Abstract A stable liquid composition which comprises a colloidal dispersion of finely-divided, magnetic particles in a liquid polar carrier and a dispersing amount of a surfactant, which surfactant comprises a phosphoric acid ester of a long-chain alcohol, the alcohol compatible with the polar carrier, to provide a stable ferrofluid composition.
Inventors
- 👤 John E. Wyman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:54
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
47 words
A stable ferrofluid composition, which composition comprises a colloidal dispersion of finely-divided magnetic particles in a liquid carrier and a dispersing amount of a dispersing agent, which agent comprises an acid phosphoric acid ester of a long-chain alcohol, the long-chain alcohol compatible with the liquid polar carrier.
Claim 2
Dependent Claim
47 words
A stable ferrofluid composition, which composition comprises a colloidal dispersion of finely-divided magnetic particles in a liquid carrier and a dispersing amount of a dispersing agent, which agent comprises an acid phosphoric acid ester of a long-chain alcohol, the long-chain alcohol compatible with the liquid polar carrier.
Claim 3
Dependent Claim
21 words
The composition of claim 1 wherein the dispersing agent comprises from about 1:1 to 20:1 by volume of the magnetic particles.
Claim 4
Dependent Claim
13 words
The composition of claim 1 wherein the magnetic particles are activated magnetite particles.
Claim 5
Dependent Claim
18 words
The composition of claim 1 wherein the composition has a viscosity of from about 50 to 2000 cps.
Claim 6
Dependent Claim
20 words
The composition of claim 1 wherein the magnetic particles comprise from about 1% to 10% by volume of the composition.
Claim 7
Dependent Claim
21 words
The composition of claim 1 wherein the magnetic particles have an average particle size of from about 20 to 500 Angstroms.
Claim 8
Dependent Claim
17 words
The composition of claim 1 wherein the composition has a gauss of from about 200 to 775.
Claim 9
Dependent Claim
23 words
The composition of claim 1 wherein the dispersing agent comprises a monophosphate or diphosphate ester of a C 6 -C 12 aliphatic alcohol.
Claim 10
Dependent Claim
24 words
The composition of claim 1 wherein the dispersing agent comprises a monophosphate or diphosphate ester of a C 2 -C 3 alkoxylated aliphatic alcohol.
Claim 11
Dependent Claim
20 words
The composition of claim 1 wherein the dispersing agent comprises the monophosphate or diphosphate acid ester of an ethoxylated alkanol.
Claim 12
Dependent Claim
23 words
The composition of claim 1 wherein the dispersing agent comprises a phosphate acid ester of an ethoxylated C 8 -C 10 alkylated phenol.
Claim 13
Dependent Claim
23 words
The composition of claim 1 wherein the magnetic particles are coated with a dispersant which is compatible with a nonpolar organic liquid carrier.
Claim 14
Dependent Claim
12 words
The composition of claim 12 wherein the dispersant comprises a fatty acid.
Claim 15
Dependent Claim
19 words
The composition of claim 1 wherein the dispersing agent comprises a phosphate acid ester of a nonylphenol polyethyleneoxy ethanol.
Claim 16
Dependent Claim
23 words
The composition of claim 1 wherein the liquid carrier is a liquid polar carrier and comprises an organic polyester or a trimellitate ester.
Claim 17
Dependent Claim
24 words
The composition of claim 15 wherein the liquid organic polar carrier comprises a diester or triester of adipic, citric, azeleic, phthalic or trimellitic acid.
Claim 18
Dependent Claim
22 words
The composition of claim 1 wherein the dispersing agent comprises a phosphate acid ester of a C 8 -C 20 fatty alcohol.
Claim 19
Dependent Claim
19 words
The composition of claim 1 wherein the liquid carrier is a nonpolar liquid carrier which comprises a alphaolefinic oil.
Claim 20
Dependent Claim
32 words
The composition of claim 1 wherein the dispersing agent is present in an excess of from about 10 to 90 percent by weight over the stoichiometric dispersing amount of the dispersing agent.
Claim 21
Dependent Claim
27 words
The composition of claim 1 wherein the ferrofluid composition is characterized by being essentially free of magnetic particles having a diameter of about 60 Angstroms or less.
Claim 22
Dependent Claim
45 words
A stable ferrofluid composition, which composition comprises a colloidal dispersion of finely-divided magnetite particles in an organic liquid polar carrier and a dispersing amount of a dispersing agent, which dispersing agent comprises an acid phosphoric acid ester of a C 2 -C 3 alkoxylated alcohol.
Claim 23
Dependent Claim
45 words
A stable ferrofluid composition, which composition comprises a colloidal dispersion of finely-divided magnetite particles in an organic liquid polar carrier and a dispersing amount of a dispersing agent, which dispersing agent comprises an acid phosphoric acid ester of a C 2 -C 3 alkoxylated alcohol.
Claim 24
Dependent Claim
20 words
The composition of claim 21 wherein the dispersing agent comprises a phosphoric acid ester of an ethoxylated aliphatic linear alcohol.
Claim 25
Dependent Claim
19 words
The composition of claim 21 wherein the dispersing agent comprises a phosphoric acid ester of a nonylphenoxy polyethyleneoxy ethanol.
Claim 26
Dependent Claim
20 words
The composition of claim 21 which includes a dispersant coated onto the magnetite particles, the dispersant comprising a fatty acid.
Claim 27
Dependent Claim
25 words
The composition of claim 24 wherein the composition has a minimum viscosity of 50 cps and has a gauss of from about 50 to 775.
Claim 28
Dependent Claim
44 words
A stable ferrofluid composition, which composition comprises a colloidal dispersion of finely-divided magnetic particles in a nonpolar liquid carrier and a dispersing amount of a dispersing agent which dispersing agent comprises an acid phosphoric acid ester of a C 8 -C 20 fatty alcohol.
Claim 29
Dependent Claim
44 words
A stable ferrofluid composition, which composition comprises a colloidal dispersion of finely-divided magnetic particles in a nonpolar liquid carrier and a dispersing amount of a dispersing agent which dispersing agent comprises an acid phosphoric acid ester of a C 8 -C 20 fatty alcohol.
Claim 30
Dependent Claim
20 words
The composition of claim 26 which includes a dispersant coated onto the magnetite particles, the dispersant comprising a fatty acid.
Claim 31
Dependent Claim
14 words
The composition of claim 26 wherein the nonpolar liquid carrier comprises an alphaolefinic oil.
Claim 32
Dependent Claim
19 words
The composition of claim 26 wherein the dispersing agent comprises an acid phosphoric acid ester of a stearyl alcohol.
References Cited (Backward Citations)
GB705050A
Cited
FR1089293A
Cited
FR1236393A
Cited
US3531413A
Cited
US3700595A
Cited
US3764540A
Cited
US3843540A
Cited
US3917538A
Cited
US4333988A
Cited
US4208294A
Cited
US4285801A
Cited
US4315827A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-02-06 | 1987-08-08 | 1988-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-06 | 1991-08-08 | 1992-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-06 | 1995-08-08 | 1996-02-07 | $7700.00 | Window Closed / Lapsed |