RARE-EARTH BONDED MAGNET, RARE-EARTH BONDED MAGNETIC COMPOSITION AND METHOD FOR MANUFACTURING RARE-EARTH BONDED MAGNET

摘要

A rare earth bond magnet formed by combining a rare earth magnet powder with a bonding resin is produced by extrusion molding or injection molding. The rare earth bonded magnet produced by extrusion molding has a content of rare earth magnet powder in the range of 78.1 to 83 vol%. In addition, the rare earth bonded magnet produced by injection molding has a content of rare earth magnet powder of 68 to 76 vol%. As the rare earth magnet powder, for example, Sm-Co-based alloys, R-Fe-B-based alloys (wherein R is at least one of the rare earth elements containing Y), and at least one of the Sm-Fe-N-based alloys are suitable. Is used. As said thermoplastic resin, polyamide, a liquid crystal polymer, and PPS are used suitably, for example. In this rare earth bonded magnet, the preferred porosity is 2 vol% or less. Such rare earth bonded magnets are kneaded with a rare earth bonded magnet composition formed by mixing a rare earth magnet powder and a thermoplastic resin, and are produced by extrusion molding or injection molding using the kneaded product. The rare earth bonded magnet composition provided for extrusion molding contains 77.6 to 82.5 vol% of the rare earth magnet powder, and the rare earth bonded magnet composition provided for injection molding contains 67.6 to 75.5 vol% of the rare earth magnet powder. Moreover, it is preferable that such a rare earth bond magnet composition contains antioxidant, such as a chelating agent. With the above structure, a rare earth bonded magnet with a high amount of mechanical properties and high mechanical strength can be obtained with a small amount of bonding resin.