Toda Kogyo Corporation

Hiromitsu Sakurai

Yasuhiko Fujii

Koso Aoki

Yoji Okano

Kazumi Yamamoto

Yasushi Nishio

Shinji Uemoto

Tomohiro Dote

Norihiro Fukushina

Nobuya Shimo

Satoshi Nomura

Kazushi Nishimoto

The present invention relates to ferrite particles for bonded magnets and a resin composition for bonded magnets which can provide a bonded magnet molded product capable of realizing a high magnetic force and a complicated multipolar waveform owing to such a feature that the ferrite particles are readily and highly oriented against an external magnetic field in a flowing resin upon injection molding, as well as a bonded magnet molded product obtained by injection-molding the above composition. According to the present invention, there are provided ferrite particles for bonded magnets which have a crystallite size of not less than 500 nm as measured in an oriented state by XRD, and an average particle diameter of not less than 1.30 μm as measured by Fisher method; a resin composition for bonded magnets; and a molded product obtained by injection-molding the composition.

Ferrite particles for bonded magnets, resin composition for bonded magnets, and molded product using the same

The present invention relates to ferrite particles for bonded magnets and a resin composition for bonded magnets which can provide a bonded magnet molded product capable of realizing a high magnetic force and a complicated multipolar waveform owing to such a feature that the ferrite particles are readily and highly oriented against an external magnetic field in a flowing resin upon injection molding, as well as a bonded magnet molded product obtained by injection-molding the above composition. According to the present invention, there are provided ferrite particles for bonded magnets which have a crystallite size of not less than 500 nm as measured in an oriented state by XRD, and an average particle diameter of not less than 1.30 &#x3bc;m as measured by Fisher method; a resin composition for bonded magnets; and a molded product obtained by injection-molding the composition.

According to the present invention, there are provided ferrite particles for bonded magnets and a resin composition for bonded magnets which are capable of producing a bonded magnet molded product having a good tensile elongation and exhibiting excellent magnetic properties, as well as a bonded magnet molded product such as a rotor which is obtained by using the resin composition. The present invention relates to ferrite particles for bonded magnets having a bulk density of not less than 0.5 g/cmand less than 0.6 g/cmand a degree of compaction of not less than 65%, a resin composition for bonded magnets using the ferrite particles, and a molded product obtained by using the ferrite particles and the resin composition.

The object of the present invention relates to ferrite particles for bonded magnets and a resin composition for bonded magnets which is capable of obtaining a bonded magnet molded product having a good magnetic force and a magnetic waveform as well as high iHc and Hk by injection molding. The present invention aims at providing a bonded magnet molded product using the ferrite particles and the resin composition. The aforementioned object of the present invention can be achieved by ferrite particles for bonded magnets which have a crystal distortion of not more than 0.14 as measured by XRD, and an average particle diameter of not less than 1.30 &#x3bc;m as measured by Fisher method; a resin composition for bonded magnets; and a molded product obtained by injection-molding the resin composition.

The present invention relates to ferrite particles for bonded magnets having a bulk density of not more than 0.75 g/cmand a degree of compaction of not less than 65%, a resin composition for bonded magnets using the ferrite particles and the composition, and a rotor. The ferrite particles for bonded magnets and the resin composition for bonded magnets according to the present invention are capable of providing a bonded magnet molded product having a good tensile elongation and an excellent magnetic properties.

Black iron-based particles comprise a FeTiO&#x2014;FeOsolid solution or a mixed composition of a FeTiO&#x2014;FeOsolid solution and an iron-based oxide having a spinel structure, and having a Ti content of from more than 10.0 atm % to 40.0 atm %, calculated as Ti, based on whole Fe, and a blackness (L* value) of 6 to 13.

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Otake, Japan

Hiromitsu Sakurai