Patent US4956113A successfully refreshed from Google Patents.
US4956113A
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Process for preparing a magnetic fluid
Assignee: Nok Corp
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Filing: 1989-02-14
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Granted: 1990-09-11
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Expires: 2009-02-14
Abstract
Abstract A magnetic fluid containing fine particles of ferrite stably dispersed in a low vapor pressure base oil is prepared by adding N-polyalkylenepolyamine-substituted alkenylsuccinimide (and a low vapor pressure base oil) to a suspension of fine particles of surfactant-adsorbed ferrite dispersed in a low boiling point hydrocarbon solvent, heating the resulting mixture, separating the hydrocarbon solvent therefrom, adding a low vapor pressure base oil and a specific dispersing agent to the fine particles of N-polyalkylenepolyamine-substituted alkenylsuccinimide-coated ferrite as the residues and subjecting the resulting mixture to a dispersion treatment.
Inventors
- 👤 Takao Kanno
- 👤 Yutaka Koda
- 👤 Hirokazu Nagato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:43
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
155 words
A process for preparing a magnetic fluid which comprises: (a) dispersing particles of surfactant-adsorbed ferrite having particle sizes of about 50 Å to about 300 Å in a hydrocarbon solvent having a boiling point of about 60° C. to about 200° C. to thereby form a suspension, (b) admixing said suspension with a N-polyalkylenepolyamine-substituted alkenylsuccinimide, (c) heating the resulting mixture at a temperature of at least 70° C. to thereby remove said hydrocarbon solvent from said mixture, and recovering particles of N-polyalkylene-polyamine-substituted alkenylsuccinimide-coated ferrite; (d) admixing said recovered particles of ferrite with: (1) a base oil having a vapor pressure of not more than 0.1 mm Hg at 25° C., and (2) a dispersing agent selected from the group consisting of (i) N-polyalkylenepolyamine-substituted alkenyl succinimide, (ii) a phosphoric acid ester having a mono- or di-oxyalkylene substituent group, and (iii) a nonionic surfactant and (e) subjecting the mixture resulting from step (d) to a dispersion treatment.
Claim 2
Dependent Claim
155 words
A process for preparing a magnetic fluid which comprises: (a) dispersing particles of surfactant-adsorbed ferrite having particle sizes of about 50 Å to about 300 Å in a hydrocarbon solvent having a boiling point of about 60° C. to about 200° C. to thereby form a suspension, (b) admixing said suspension with a N-polyalkylenepolyamine-substituted alkenylsuccinimide, (c) heating the resulting mixture at a temperature of at least 70° C. to thereby remove said hydrocarbon solvent from said mixture, and recovering particles of N-polyalkylene-polyamine-substituted alkenylsuccinimide-coated ferrite; (d) admixing said recovered particles of ferrite with: (1) a base oil having a vapor pressure of not more than 0.1 mm Hg at 25° C., and (2) a dispersing agent selected from the group consisting of (i) N-polyalkylenepolyamine-substituted alkenyl succinimide, (ii) a phosphoric acid ester having a mono- or di-oxyalkylene substituent group, and (iii) a nonionic surfactant and (e) subjecting the mixture resulting from step (d) to a dispersion treatment.
Claim 3
Dependent Claim
32 words
A process according to claim 1 wherein the concentration of the particles of surfactant-adsorbed ferrite dispersed in the said hydrocarbon solvent in step (a) is about 0.01 to about 30% by weight.
Claim 4
Dependent Claim
42 words
A process according to claim 1 wherein in step (b) about 0.1 to about 10% by weight, on the basis of said hydrocarbon solvent that forms the suspension, of the N-polyalkylenepolyamine-substituted alkenylsuccinimide is added to the suspension dispersed in said hydrocarbon solvent.
Claim 5
Dependent Claim
23 words
A process according to claim 1 wherein the heating in step (c) is carried out at the reflux temperature of said hydrocarbon solvent.
Claim 6
Dependent Claim
23 words
A process according to claim 4 wherein in step (c) said hydrocarbon solvent is distilled off by the heating at the reflux temperature.
Claim 7
Dependent Claim
17 words
A process according to claim 1, wherein said base oil in step (d) is a natural oil.
Claim 8
Dependent Claim
17 words
A process according to claim 1 wherein said base oil in step (d) is a synthetic oil.
Claim 9
Dependent Claim
29 words
A process according to claim 7 wherein said synthetic oil is a polybutene, a dicarboxylic acid diester, a polyol, a polyolpolyester, a phosphoric acid triester or a lubricating oil.
Claim 10
Dependent Claim
41 words
A process according to claim 1 wherein said base oil in step (d) is used in such an amount as to make a dispersion concentration of the particles of ferrite in the magnetic fluid about 10 to about 50% by weight.
Claim 11
Dependent Claim
30 words
A process according to claim 1 wherein in step (d) about 1 to about 20% by weight, on the basis of the base oil, of the dispersing agent is used.
Claim 12
Dependent Claim
21 words
A process according to claim 1 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 13
Dependent Claim
21 words
A process according to claim 2 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 14
Dependent Claim
21 words
A process according to claim 3 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 15
Dependent Claim
21 words
A process according to claim 4 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 16
Dependent Claim
21 words
A process according to claim 5 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 17
Dependent Claim
21 words
A process according to claim 6 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 18
Dependent Claim
21 words
A process according to claim 7 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 19
Dependent Claim
21 words
A process according to claim 8 wherein the temperature in step (c) is from about 200° C. to about 300° C.
Claim 20
Dependent Claim
42 words
A process according to claim 9 wherein said base oil is used in step (d) in an amount so as to make a dispersion concentration of the particles of ferrite in the magnetic fluid of about 10 to about 50% by weight.
Claim 21
Dependent Claim
34 words
A process according to claim 10 wherein in step (d) about 10 to about 20% by weight, on the basis of said base oil, of said dispersing agent is added to said base oil.
Claim 22
Dependent Claim
103 words
A process for preparing a magnetic fluid which comprises: (a) dispersing particles of surfactant-adsorbed ferrite having particle size of about 50 Å to about 300 Å in a hydrocarbon solvent having a boiling point of about 60° C. to about 200° C. to thereby form a suspension, (b) admixing said suspension with a N-polyalkylenepolyamine-substituted alkenylsuccinimide and a base oil having a vapor pressure of not more than 0.1 mm Hg at 25° C., and (c) heating the resulting mixture at a temperature of at least 70° C. to thereby remove said hydrocarbon solvent from said mixture, and recovering particles of N-polyalkylene-polyamine-substituted alkenylsuccinimide-coated ferrite.
Claim 23
Dependent Claim
103 words
A process for preparing a magnetic fluid which comprises: (a) dispersing particles of surfactant-adsorbed ferrite having particle size of about 50 Å to about 300 Å in a hydrocarbon solvent having a boiling point of about 60° C. to about 200° C. to thereby form a suspension, (b) admixing said suspension with a N-polyalkylenepolyamine-substituted alkenylsuccinimide and a base oil having a vapor pressure of not more than 0.1 mm Hg at 25° C., and (c) heating the resulting mixture at a temperature of at least 70° C. to thereby remove said hydrocarbon solvent from said mixture, and recovering particles of N-polyalkylene-polyamine-substituted alkenylsuccinimide-coated ferrite.
Claim 24
Dependent Claim
32 words
A process according to claim 21 wherein a dispersion concentration of said particles of surfactant-adsorbed ferrite dispersed in said hydrocarbon solvent in step (a) is about 0.1 to about 30% by weight.
Claim 25
Dependent Claim
37 words
A process according to claim 21 wherein in step (b) about 0.1 to about 10% by weight, on the basis of said hydrocarbon solvent that forms said suspension, of the N-polyalkylenepolyamine-substituted alkenylsuccinimide is added to said suspension.
Claim 26
Dependent Claim
17 words
A process according to claim 21 wherein said base oil in step (b) is a natural oil.
Claim 27
Dependent Claim
17 words
A process according to claim 21 wherein said base oil in step (b) is a synthetic oil.
Claim 28
Dependent Claim
29 words
A process according to claim 25 wherein said synthetic oil is a polybutene, a dicarboxylic acid diester, a polyol, a polyolpolyester, a phosphoric acid triester or a lubricating oil.
Claim 29
Dependent Claim
38 words
A process according to claim 21 wherein said base oil is used in such an amount as to make a dispersion concentration of the particles of ferrite in the magnetic fluid about 10 to about 50% by weight.
Claim 30
Dependent Claim
31 words
A process according to claim 21 wherein about 1 to about 20% by weight, on the basis of said base oil, of a dispersing agent is added to said base oil.
Claim 31
Dependent Claim
20 words
A process according to claim 21 wherein said heating is carried out at the reflux temperature of said hydrocarbon solvent.
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