| 摘要 |
PURPOSE:To efficiently obtain a long-sized cylindrical compound magnet having excellent magnetic characteristics, dimensional stability and thermal shock resistance by a method wherein an ethylene-vinyl acetate copolymer having specific characteristics is used as base resin. CONSTITUTION:A long-sized anisotropic compound magnet molded body is mainly composed of ferromagnetic powder and ethylene-vinyl acetate copolymer, the content of vinyl acetate of the copolymer is 10wt% or less, the compound magnet molded body has no warpage and, at the same time, it has excellent magnetic characteristics. Also, in the long-sized anisotropic compound magnet molded body, it has the melt index (ASTM D1238) containing ethylene-vinyl acetate copolymer of 3g/10min or above, and it has the weight ratio of 80-96:20-4 between ferromagnetic powder and ethylene-vinyl acetate copolymer. The long- sized compound magnet can have an arbitrary shape of cross-section, but a cylindrical shape is desirable for the reason that it is easy to manufacture. The length-diameter ratio of the cylindrical compound magnet is ordinarily about 5 or above, but it is substantially about 10 or above when it is used for a magnet roll. |
