Compositions – Magnetic – With wax – bitumen – resin – or gum
Patent
1987-02-09
1989-02-28
Robinson, Ellis P.
Compositions
Magnetic
With wax, bitumen, resin, or gum
428403, 428407, 428328, 428329, 428900, G11B 568
Patent
active
048083267
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a magnetic composition to be used as a magnetic core for a transformer or for high-frequency welding of a laminated tube and a process for producing a magnetic molding from the magnetic composition, and more particularly to a resin-bonded magnetic composition prepared by bonding magnetic powder with synthetic resin, which enables molding of materials of complicated form at low temperatures, and further which improves heat resistance, mechanical strength, mechanical workability and initial magnetic permeability of obtained moldings and to a process for producing a magnetic molding from the magnetic composition.
BACKGROUND ART
In recent years, in accordance with the diversification and microminiaturization of electronic devices, parts and the like, the developments of magnetic moldings having complicated forms or microstructures are intensily required in various technical fields.
Generally, moldings produced by pressing ferromagnetic powder such as ferrite powder and then sintering the pressed ferromagnetic powder at a high temperature of at least 1000.degree. C. are usually used. However, the moldings are largely contracted when the pressed ferromagnetic powder is sintered, and a great cost for producing is needed since the yield or the like is remarkably lowered when producing moldings having complicated forms or microstructures. Further, such magnetic moldings have many problems that it is difficult to be mechanically processed, that is, the obtained magnetic moldings are easily chipped off and brittle. Therefore, the developments of a resin-bonded magnetic composition having highly effective properties are required to solve these problems in various technical fields.
Hence, a known resin-bonded magnetic composition used as a magnetic core for a transformer and the like is produced by mixing iron powder or ferrite powder with resin components such as polyphenylene sulfide, epoxy resin, polyalkylene terephthalate, polyethylene, polypropylene, polybutene, polyvinyl chloride, ABS resin and AS resin and molding the mixture by hot-pressing.
However, since prior magnetic moldings produced by mixing resin components such as polyphenylene sulfide and epoxy resin and molding the mixture by hot-pressing have many problems in that the heat resistance is not sufficient, the mechanical strength is low and the initial magnetic permeability is low, the range of their uses is limited to a core of a coil used in a toy which does not need high reliabilities and high properties, and the like. Therefore, the fact is that the magnetic moldings have not yet been applied to industrial electronic devices and the like.
As the results of the present inventors' researches, the inventors have eventually found a resin-bonded magnetic composition having excellent heat resistance, moldability, mechanical workability, mechanical strength and initial magnetic permeability and a process for producing a magnetic molding from the magnetic composition, and the present invention was accomplished.
DISCLOSURE OF THE INVENTION
A resin-bonded magnetic composition of the present invention comprises 80 to 95 weight % of ferromagnetic powder, 5 to 20 weight % of highly heat-resistant thermosetting resin powder and 0.1 to 1 weight % of metal chelate compound.
Examples of the above-mentioned ferromagnetic powder are, for instance, ferrite powder, iron powder, Co-compound powder such as borocube, permalloy powder, alnico magnetic powder, neodymium magnetic powder, amorphous magnetic powder, and the like. These powders may be employed alone or in admixture thereof. Among them, since ferrite powder is excellent in moldability, the ferrite powder is preferably used in the present invention. These ferromagnetic powders are usually ground to have a particle size within the range of 50 to 300 mesh.
Examples of the highly heat-resistant thermosetting resin powder are, for instance, prepolymer obtained by reacting a bisimide compound of unsaturated dicarboxylic acid with a polyamine compound having at lea
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Kizaki Takeo
Nakazawa Yukio
Tanino Katsumi
Robinson Ellis P.
Takeuchi Press Industries Co., Ltd.
Toyama Prefecture
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