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

Patent metadata

Field	Value
Publication number	US-9249033-B2
Application number	US-53096308-A
Country	US
Kind code	B2
Filing date	Mar 14, 2008
Priority date	Mar 14, 2007
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

The present invention relates to ferrite particles for bonded magnets and a resin composition for bonded magnets which exhibit a good moldability, in particular, a good mechanical strength even when rapidly quenched upon injection-cooling, and is capable of producing a bonded magnet molded product having excellent magnetic properties, as well as a bonded magnet molded product such as a magnet roll using the ferrite particles and the resin composition. There are provided ferrite particles for bonded magnets which comprise phosphorus adsorbed and/or incorporated in ferrite, in which a content of the phosphorus in the ferrite is 120 to 5000 mg/kg (0.012 to 0.50% by weight) in terms of P; a resin composition for bonded magnets; and a magnet roll.

First claim

The invention claimed is:

1. A resin composition for a bonded magnet, comprising an organic binder component and magnetoplumbite-type ferrite magnetic particles for bonded magnets in which the magnetic particles are coated with a coating agent consisting of a phosphorus compound and a silane coupling agent,
a content of the magnetic particles in the resin composition for bonded magnets being 70 to 95% by weight based on the weight of the resin composition;
a content of the phosphorus compound in the resin composition being 100 to 1060 mg/kg (0.010 to 0.1060% by weight) in terms of P wherein the phosphorus compound is selected from orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, triphosphoric acid and tetraphosphoric acid; and
a content of silicon in the resin composition being 1000 to 10000 mg/kg (0.10 to 1.0% by weight) in terms of SiO 2 .

2. The resin composition for a bonded magnet of claim 1 , wherein the magnetoplumbite-type ferrite particles are Sr-based ferrite particles, Ba-based ferrite particles or a mixture thereof.

3. The resin composition for a bonded magnet of claim 1 , wherein the BET specific surface area value of the ferrite particles is 1.0 to 3.0 m 2 /g.

4. The resin composition for a bonded magnet of claim 1 , wherein the coercive force Hc of the ferrite particles is 135 to 279 kA/m (1700 to 3500 Oe).

5. A resin composition for a bonded magnet, comprising an organic binder component and magnetoplumbite-type ferrite particles for bonded magnets in which the magnetic particles are coated with a coating agent consisting of a phosphorus compound and a silane coupling agent,
a content of the magnetic particles in the resin composition for bonded magnets being 70 to 95% by weight based on the weight of the resin composition;
a content of the phosphorus in the resin composition being 100 to 1060 mg/kg (0.010 to 0.1060% by weight) in terms of P wherein the phosphorus compound is selected from sodium pyrophosphate, sodium metaphosphate, potassium metaphosphate and sodium hexametaphosphate; and
a content of silicon in the resin composition being 1000 to 10000 mg/kg (0.10 to 1.0% by weight) in terms of SiO 2 .

6. The resin composition for a bonded magnets of claim 5 , wherein the magnetoplumbite-type ferrite particles are Sr-based ferrite particles, Ba-based ferrite particles or a mixture thereof.

7. The resin composition for a bonded magnets of claim 5 , wherein the BET specific surface area value of the ferrite particles is 1.0 to 3.0 m 2 /g.

8. The resin composition for a bonded magnets of claim 5 , wherein the coercive force Hc of the ferrite particles is 135 to 279 kA/m (1700 to 3500 Oe).

9. The resin composition for a bonded magnet of claim 5 , having a bending strength of a molded product comprising the resin composition of 980 N or more.

Assignees

• Fujii Yasuhiko
• Nishio Yasushi
• Kanefuji Kazuhisa
• Ishida Tatsuya
• Takaragi Shigeru
• Toda Kogyo Corp

Inventors

• Fujii Yasuhiko
• Nishio Yasushi
• Kanefuji Kazuhisa
• Ishida Tatsuya
• Takaragi Shigeru

Classifications

• C04B35/2683

  Other ferrites containing alkaline earth metals or lead · CPC title

• C04B2235/444

  Halide containing anions, e.g. bromide, iodate, chlorite · CPC title

• C01G49/0036 Primary

  containing one alkaline earth metal, magnesium or lead · CPC title

• C04B2235/5436

  micrometer sized, i.e. from 1 to 100 micron · CPC title

• C04B2235/3215

  Barium oxides or oxide-forming salts thereof · CPC title