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

Patent metadata

Field	Value
Publication number	US-2023078224-A1
Application number	US-202217984519-A
Country	US
Kind code	A1
Filing date	Nov 10, 2022
Priority date	Oct 2, 2013
Publication date	Mar 16, 2023
Grant date	—

Abstract

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/cm 3 and less than 0.6 g/cm 3 and 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.

First claim

1 . A process for producing ferrite particles comprising:
(a) blending and mixing raw material particles at a predetermined mixing ratio; (b) calcining the resulting mixed raw material particles from (a) at a temperature of 900 to 1250° C. in atmospheric air; (c) subjecting the particles obtained from (b) to pulverization and washing with water; (d) subjecting the resulting particles from (c) to annealing heat treatment at a temperature of 700 to 1100° C. in atmospheric air; (e) subjecting the obtained particles from (d) to compaction and grinding; and (f) subjecting the obtained particles from (e) to deaggregation treatments.

2 . The process for producing ferrite particles according to claim 1 , wherein the ferrite particles have a bulk density of not less than 0.5 g/cm 3 and less than 0.6 g/cm 3 and a degree of compaction of not less than 65%.

3 . The process for producing ferrite particles according to claim 1 , wherein the ferrite particles have an average particle diameter of 0.9 to 3.0 μm.

4 . The process for producing ferrite particles according to claim 1 , wherein the ferrite particles are magnetoplumbite-type ferrite particles.

5 . The process for producing ferrite particles according to claim 1 , wherein a coercive force Hc of the ferrite particles is 206.9 to 279 kA/m (2600 to 3500 Oe) and the ferrite particles are magnetoplumbite-type ferrite particles.

6 . The ferrite particles obtained by the process of claim 1 .

Assignees

• Toda Kogyo Corp

Inventors

• Nishio Yasushi
• Sakurai Hiromitsu
• Fukushina Norihiro
• Fujii Yasuhiko

Classifications

• C04B2235/6022

  Injection moulding · CPC title

• C01P2004/20

  extending in two dimensions, e.g. plate-like · CPC title

• C04B35/6261

  Milling · CPC title

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C01P2006/11

  Powder tap density · CPC title