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EP0055065A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Magnetic fluid

Assignee: Panasonic Holdings Corp
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Filing: 1981-12-15
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Granted: —
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Expires: 2001-12-15
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Abstract

Abstract This invention provides a magnetic fluid having a rich hue and containing an organic compound as dispersion medium. The magnetic fluid of this invention is constructed by mixing, into a magnetic dispersion, a colorant prepared by beforehand treating a coloring material with a solubilizing treating agent or a dispersibilizing treating agent. Said solubilizing treating agent or dispersibilizing treating agent has a hydrophobic group and a functional group adsorbable or linkable to said coloring material. As said coloring material, a dyestuff, an organic pigment or an inorganic pigment is used. A colorant prepared by subjecting an intermediate of said coloring material to said treatment is also usable. Further, a colorant prepared by pretreating a coloring material so as to give the coloring material an adsorbability or a linkability to said solubilizing treating agent or dispersibilizing treating agent and then subjecting the beforehand pretreated coloring material to said treatment is also usable. The magnetic fluid of this invention can retain its initial hue stably for a long period of time, and its hue can be changed without substantially changing the properties of magnetic fluid such as magnetization, viscosity and the like. Accordingly, the magnetic fluid of this invention can be applied extensively to all the use fields of magnetic dispersions, and it exhibits a particularly great effect when applied to uses of developer or ink in the field of printing and recording.

Inventors

  • 👤 Keiichi Yubakami
  • 👤 Mamoru Soga
  • 👤 Nobuo Sonoda
  • 👤 Wataru Shimotsuma

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-29 22:03
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44; H01F1/445

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 52 words
A magnetic fluid characterized by being constructed from a mixture consisting of a magnetic dispersion prepared by dispersing magnetic fine particles into an organic dispersion medium by the aid of a surfactant and a colorant prepared by beforehand treating a coloring material with a solubilizing treating agent or a dispersibilizing treating agent.
Claim 2
Dependent Claim 52 words
A magnetic fluid characterized by being constructed from a mixture consisting of a magnetic dispersion prepared by dispersing magnetic fine particles into an organic dispersion medium by the aid of a surfactant and a colorant prepared by beforehand treating a coloring material with a solubilizing treating agent or a dispersibilizing treating agent.
Claim 3
Dependent Claim 42 words
A magnetic fluid according to Claim 1, wherein said magnetic, fine particle is a ferrite compound and s.aid organic dispersion medium is at least one member selected from the group consisting of hydrocarbon compounds, ether compounds, ester compounds and fluorinated hydrocarbon compounds.
Claim 4
Dependent Claim 28 words
A magnetic fluid according to Claim 2, wherein said hydrocarbon compound is an aliphatic hydrocarbon compound having 8-20 carbon atoms either alone or in the form of mixture.
Claim 5
Dependent Claim 35 words
A magnetic fluid according to Claim 1 or Claim 2, wherein said solubilizing treating agent or said dispersibilizing treating agent has a hydrophobic group and a functional group adsorbable or linkable to the coloring material.
Claim 6
Dependent Claim 31 words
A magnetic fluid according to Claim 4, wherein said hydrophobic group is at least one member selected from the group consisting of alkyl groups, cycloalkyl groups, alkenyl groups and aralkyl groups.
Claim 7
Dependent Claim 63 words
A magnetic fluid according to Claim 4, wherein said functional group of solubilizing treating agent or dispersibilizing treating agent adsorbable or linkable to coloring material is at least one member selected from the group consisting of carboxyl group, carboxylic acid anhydride group, carbonyl chloride group, carbonyl bromide group, sulfonic acid group, sulfonyl chloride group, primary amino group, secondary amino group and phenyl group.
Claim 8
Dependent Claim 51 words
A magnetic fluid according to Claim 1 or Claim 2, wherein said coloring material is a coloring material which has been pretreated by at least one reaction selected from the group consisting of amination, carboxylation, hydroxylation, conversion of carboxyl group to carbonyl chloride and conversion of carboxyl group to carbonyl bromide.
Claim 9
Dependent Claim 20 words
A magnetic fluid according to Claim 1 or Claim 2, wherein said coloring material is an intermediate of coloring material.
Claim 10
Dependent Claim 50 words
A magnetic fluid according to any of Claim 1 and Claim 2, wherein the linkage between the solubilizing treating agent or dispersibilizing treating agent and the coloring material is at least one member selected from the group consisting of amide linkage, sulfonamide linkage, ester linkage, N-alkyl linkage and acyl linkage.

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