US5013471A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic fluid, method for producing it and magnetic seal means using the same
Assignee: Panasonic Holdings Corp
•
Filing: 1989-05-31
•
Granted: 1991-05-07
•
Expires: 2009-05-31
Abstract
Abstract Disclosed herein are a magnetic fluid, a method for the production thereof, and a magnetic seal apparatus using the same, characterized in that the surfaces of ferromagnetic particles are covered with a monomolecular adsorbed film composed of a chloro-silane type surfactant, and the coated particles are dispersed in an oil. A magnetic seal apparatus using such a magnetic fluid.
Inventors
- 👤 Kazufumi Ogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:58
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44; B; B82; B82Y; B82Y30/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
51 words
A magnetic fluid comprising particles of a ferromagnetic material having their surfaces covered with a monomolecular chemically adsorbed film formed from a chloro-silane surfactant, wherein the number of carbons in the hydrocarbon chain of the chloro-silane surfactant is 10 to 25, said particles of magnetic material being dispersed in an oil.
Claim 2
Dependent Claim
51 words
A magnetic fluid comprising particles of a ferromagnetic material having their surfaces covered with a monomolecular chemically adsorbed film formed from a chloro-silane surfactant, wherein the number of carbons in the hydrocarbon chain of the chloro-silane surfactant is 10 to 25, said particles of magnetic material being dispersed in an oil.
Claim 3
Dependent Claim
35 words
A magnetic fluid according to claim 1, wherein some of the hydrogen atoms of the hydrocarbon chain of the chloro-silane surfactant are substituted by fluorine atoms, and a fluorinated oil is used as the oil.
Claim 4
Dependent Claim
34 words
A magnetic fluid according to either claim 1 or 2, wherein the chloro-silane surfactant is chemically bonded to the ferromagnetic material with --Si-O- bond at the surfaces of the particles of the ferromagnetic material.
Claim 5
Independent Claim
78 words
A method for producing a magnetic fluid comprising chemically adsorbing a chloro-silane surfactant on the surfaces of particles of a ferromagnetic material in a non-aqueous organic solvent so that silicon of said surfactant will be chemically bonded to the ferromagnetic material with --Si-O- bond at the surface of said particles of magnetic material to form a monomolecular film, said method including the step of dispersing said particles of ferromagnetic material formed with a monomolecular film in an oil.
Claim 6
Independent Claim
78 words
A method for producing a magnetic fluid comprising chemically adsorbing a chloro-silane surfactant on the surfaces of particles of a ferromagnetic material in a non-aqueous organic solvent so that silicon of said surfactant will be chemically bonded to the ferromagnetic material with --Si-O- bond at the surface of said particles of magnetic material to form a monomolecular film, said method including the step of dispersing said particles of ferromagnetic material formed with a monomolecular film in an oil.
Claim 7
Dependent Claim
21 words
The method for producing a magnetic fluid according to claim 4, wherein a molecule of the chloro-silane surfactant contains --SiCl group.
Claim 8
Dependent Claim
40 words
The method for producing a magnetic fluid according to claim 5, wherein a chemical substance represented by the formula CH 3 --(CH 2 ) n -SiCl 3 (n being an integer) of 10 to 25 is used as chloro-silane surfactant.
Claim 9
Dependent Claim
28 words
The method for producing a magnetic fluid according to claim 5 or 6, wherein the particles of ferromagnetic material are those of magnetite (Fe 3 O 4 ).
Claim 10
Dependent Claim
39 words
The method for producing a magnetic fluid according to claim 6, wherein a fluorinated oil is used as the oil, and some of the hydrogen atoms of a hydrocarbon chain in the chloro-silane surfactant are substituted by fluorine atoms.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-05-06 | 1994-11-05 | 1995-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-06 | 1998-11-05 | 1999-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-06 | 2002-11-05 | 2003-05-07 | $7700.00 | Window Closed / Lapsed |