Minebea Company, Limited

Toshihiko Miura

Noboru Menjo

Shinsaku Nishimura

Shunji Suzuki

Shuichi Nishida

Masahito Kawasaki

In a rare earth bonded magnet comprising a mixture of rare earth magnetic powder, thermosetting resin, and lubricant, the lubricant is constituted by amino-acid compound, specifically either N-lauroyl-L-lysine or N-lauroyl-asparaginic acid. The content of the amino-acid compound as lubricant in the mixture is set to range between 0.01 wt % and 1.0 wt % of the magnetic powder. Since the amino-acid compound has a high decomposition point, the resultant magnet after heat-curing treatment has a sufficient mechanical strength. Also, the amino-acid compound is nonhygroscopic, and therefore oxidation resistance and humidity resistance are good enough. Further, since the amino-acid compound produces a small amount of outgas, the resultant magnet can be suitably and reliably used in a hard disk drive which has stringent requirements, especially on outgas.

Rare earth bonded magnet including amino-acid compound as lubricant

A resin bonded rare earth magnet, compression molded from rare earth-transition alloy powder and thermosetting resin, having a magnetcomprising a mixture of thermosetting resin and rare earth-transition alloy powder with a particle size of between 20 and 300 microns, a filling materialwith particle size between 0.1 and 15 microns which is used to fill in the depressionson the surface of said magnetand is then fixed with said thermosetting resin, and a corrosion inhibiting coatmade from synthetic resin applied to the surface of said magnetwhich has been rendered smooth by the application of said filling material into the depressions on its surface.

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Iwata-gun, Japan

Toshihiko Miura