# US 8,540,929 B2 · Method for producing rare earth sintered magnet

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- Number: US 8,540,929 B2
- Document ID: US8540929B2
- Status: Granted
- Kind: B2
- Application number: 12/951,325
- Filed: 2010-11-22
- Published: 2011-05-26
- Granted: 2013-09-24
- Earliest claimed: 2009-11-25
- Assignees: TDK Corporation
- Applicants: Shuichiro Irie; Raitaro Masaoka; Toshiya Hozumi; Tetsuya Chiba
- Inventors: Shuichiro Irie; Raitaro Masaoka; Toshiya Hozumi; Tetsuya Chiba
- Web page: https://patentgrep.com/patent/US8540929B2

## CPC

- H01F 41/0266: {Moulding; Pressing (H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11)}
- B22F 3/1021: {Removal of binder or filler (removal of binder from ceramics C04B35/638)}
- B22F 3/20: by extruding
- C22C 19/07: based on cobalt
- C22C 33/0285: {with Cr, Co, or Ni having a minimum content higher than 5%}
- C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides}
- C22C 38/06: containing aluminium
- C22C 38/10: containing cobalt
- C22C 38/14: containing titanium or zirconium
- C22C 38/16: containing copper
- H01F 1/0557: {sintered}
- H01F 1/0577: {sintered}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

The present invention relates to a method for producing a rare earth sintered magnet including the steps of: molding a mixture of magnetic powder containing a rare earth compound and oil-extended rubber containing oil and rubber to produce a molded body; removing the oil-extended rubber from the molded body; and calcining the molded body from which the oil-extended rubber is removed to produce a rare earth sintered magnet 10.

## Claims

### Claim 1

A method for producing a rare earth sintered magnet, the method comprising the steps of:
molding a mixture of magnetic powder containing a rare earth compound and oil-extended rubber containing oil and rubber to produce a molded body;
removing the oil-extended rubber from the molded body; and
calcining the molded body from which the oil-extended rubber is removed to produce a rare earth sintered magnet,
wherein the rubber is at least one selected from a group consisting of polyisobutylene, ethylene-propylene rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber and ethylene-propylene diene monomer rubber.

### Claim 2 (depends on 1)

The method for producing a rare earth sintered magnet according to claim 1, wherein in the molding, the molded body is produced by extrusion-molding the mixture.

### Claim 3 (depends on 1)

The method for producing a rare earth sintered magnet according to claim 1, wherein the rubber is made of a polymer containing no oxygen as a constituent element.

### Claim 4 (depends on 1)

The method for producing a rare earth sintered magnet according to claim 1, wherein the rubber is made of a polymer in which bonds between carbons are only single bonds.

### Claim 5 (depends on 1)

The method for producing a rare earth sintered magnet according to claim 1, wherein the content of the magnetic powder in the mixture is 80 to 95% by mass.

### Claim 6 (depends on 1)

The method for producing a rare earth sintered magnet according to claim 1, wherein the removing of the oil-extended rubber comprises the steps of removing mainly the oil from the molded body by heating the molded body, and removing mainly the rubber from the molded body by heating the molded body.