Compound for bonded magnet, bonded magnet, method of producing same, and resin composition for bonded magnets

Patent metadata

Field	Value
Publication number	US-12230438-B2
Application number	US-202117455155-A
Country	US
Kind code	B2
Filing date	Nov 16, 2021
Priority date	Nov 18, 2020
Publication date	Feb 18, 2025
Grant date	Feb 18, 2025

Abstract

A method of producing a compound for bonded magnets, the method including: heat-curing a thermosetting resin and a curing agent having a ratio of the number of reactive groups of the curing agent to the number of reactive groups of the thermosetting resin of at least 2 but not higher than 11 to obtain an additive for bonded magnets; and kneading the additive for bonded magnets, magnetic powder, and a thermoplastic resin to obtain a compound for bonded magnets in which a filling ratio of the magnetic powder is at least 91.5% by mass.

First claim

What is claimed is:

1. A method of producing a compound for thermoplastic resin-containing bonded magnets, the method comprising:
heat-curing a thermosetting resin and a curing agent having a ratio of a number of reactive groups of the curing agent to a number of reactive groups of the thermosetting resin of at least 2 but not higher than 11 to obtain an additive for thermoplastic resin-containing bonded magnets,
wherein the additive for thermoplastic resin-containing bonded magnets is a cured product of the thermosetting resin and the curing agent; and
kneading the additive for thermoplastic resin-containing bonded magnets, magnetic powder, and a thermoplastic resin to obtain the compound for thermoplastic resin-containing bonded magnets in which a filling ratio of the magnetic powder is at least 91.5% by mass.

2. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the magnetic powder includes NdFeB-based magnetic powder and SmFeN-based anisotropic magnetic powder.

3. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the magnetic powder includes SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate.

4. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the kneading comprises:
kneading the additive for thermoplastic resin-containing bonded magnets and a thermoplastic resin to obtain a resin composition for thermoplastic resin-containing bonded magnets; and
kneading the resin composition for thermoplastic resin-containing bonded magnets and magnetic powder to obtain the compound for thermoplastic resin-containing bonded magnets.

5. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the thermoplastic resin is a nylon resin.

6. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the magnetic powder has a monodisperse particle size distribution.

7. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the magnetic powder contains Sm, Fe, and N.

8. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the compound for thermoplastic resin-containing bonded magnets comprises an organic pigment.

9. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 1 ,
wherein the magnetic powder is phosphate-coated SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate, and
the method further comprises performing a phosphate treatment comprising adding an inorganic acid to a slurry containing SmFeN-based anisotropic magnetic powder, water, and a phosphate compound so that the slurry is adjusted to have a pH of at least 1 but not higher than 4.5 to obtain the phosphate-coated SmFeN-based anisotropic magnetic powder.

10. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 9 ,
wherein the phosphate-coated SmFeN-based anisotropic magnetic powder has a phosphate content of more than 0.5% by mass.

11. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 9 ,
wherein, in the performing the phosphate treatment, the slurry is adjusted to have a pH of at least 1 but not higher than 4.5 for at least 10 minutes.

12. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 9 ,
wherein, in the performing the phosphate treatment, the slurry is adjusted to have a pH of at least 1.6 but not higher than 3.9.

13. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 9 , further comprising
heat-treating the phosphate-coated SmFeN-based anisotropic magnetic powder at a temperature of at least 150° C. but not higher than 250° C. in an oxygen-containing atmosphere.

14. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 9 ,
wherein the phosphate-coated SmFeN-based anisotropic magnetic powder has a DSC exothermic onset temperature of 170° C. or higher and a phosphate content of more than 0.5% by mass.

15. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 9 ,
wherein the phosphate-coated SmFeN-based anisotropic magnetic powder has a XRD diffraction pattern in which a ratio (I)/(II) of a diffraction peak intensity (I) of a (110) plane of αFe to a peak intensity (II) of a (300) plane of the SmFeN-based magnetic powder is not higher than 2.0×10 −2 .

16. The method of producing a compound for thermoplastic resin-containing bonded magnets according to claim 9 ,
wherein the phosphate-coated SmFeN-based anisotropic magnetic powder has a carbon content of not higher than 1,000 ppm.

17. A method of producing a thermoplastic resin-containing bonded magnet, the method comprising:
heat-curing a thermosetting resin and a curing agent having a ratio of a number of reactive groups of the curing agent to a number of reactive groups of the thermosetting resin of at least 2 but not higher than 11 to obtain an additive for thermoplastic resin-containing bonded magnets, wherein the additive for thermoplastic resin-containing bonded magnets is a cured product of the thermosetting resin and the curing agent;
kneading the additive for thermoplastic resin-containing bonded magnets, magnetic powder, and a thermoplastic resin to obtain a compound for thermoplastic resin-containing bonded magnets in which a filling ratio of the magnetic powder is at least 91.5% by mass; and
injection-molding the compound for thermoplastic resin-containing bonded magnets.

Assignees

• Nichia Corp

Inventors

• Yamanaka Satoshi
• Yano Takayuki
• Tada Shuichi
• Abe Masahiro
• Iwai Kenta

Classifications

• B29C45/0001

  characterised by the choice of material · CPC title

• B29K2505/00

  Use of metals, their alloys or their compounds, as filler · CPC title

• B29K2077/00

  Use of {PA, i.e.} polyamides, e.g. polyesteramides {or derivatives thereof}, as moulding material · CPC title

• B29K2995/0008

  Magnetic or paramagnetic · CPC title

• B29B7/88 Primary

  Adding charges {, i.e. additives} · CPC title