# US 2014/0197911 A1 · Rare-earth permanent magnet and method for manufacturing rare-earth permanent magnet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197911 A1 - Document ID: US20140197911A1 - Status: Published application - Kind: A1 - Application number: 14/232,351 - Filed: 2013-03-08 - Published: 2014-07-17 - Earliest claimed: 2012-03-12 - Assignees: Nitto Denko Corporation - Applicants: Nitto Denko Corporation - Inventors: Takashi Ozaki; Katsuya Kume; Toshiaki Okuno; Izumi Ozeki; Tomohiro Omure; Keisuke Taihaku; Takashi Yamamoto - Web page: https://patentgrep.com/patent/US20140197911A1 ## CPC - B22F 3/22: for producing castings from a slip - C22C 33/0278: {with at least one alloying element having a minimum content above 5%} - C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60} - C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides} - H01F 1/0536: {sintered} - H01F 1/0577: {sintered} - H01F 41/02: for manufacturing cores, coils, or magnets (H01F41/14 takes precedence; for dynamo-electric machines H02K15/00) - H01F 41/0273: {Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003)} - B22F 2998/10: Processes characterised by the sequence of their steps - B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy - C22C 2202/02: Magnetic - 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) - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract There are provided a rare-earth permanent magnet and a manufacturing method of a rare-earth permanent magnet capable of improving magnetic properties by optimizing magnetic field orientation. In the method, magnet material is milled into magnet powder. Next, the magnet powder and a binder are mixed to obtain a mixture 12. The thus prepared mixture 12 is then formed into a long-sheet-like shape on a supporting base 13 by hot-melt molding so as to obtain a green sheet 14. The thus formed green sheet 14 is heated to soften and a magnetic field is applied to the heated green sheet 14 for magnetic field orientation. The green sheet 14 subjected to the magnetic field orientation is sintered and thereby a permanent magnet 1 is obtained. ## Claims ### Claim 1 A manufacturing method of a rare-earth permanent magnet comprising steps of: milling magnet material into magnet powder; preparing a mixture of the magnet powder and a binder; obtaining a green sheet through thermally melting and forming the mixture into a sheet-like shape; heating the green sheet and simultaneously/subsequently applying a magnetic field to the heated green sheet for magnetic field orientation; and sintering the green sheet subjected to the magnetic field orientation. ### Claim 2 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein, the binder is any one of a thermoplastic resin, a long-chain hydrocarbon and a fatty acid methyl ester, or any combination thereof, and in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the green sheet is heated to a temperature equal to or higher than a glass-transition point or melting point of the binder. ### Claim 3 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein, in the step of obtaining a green sheet, a base that is continuously conveyed is coated with the mixture, so as to form the green sheet on the base, and in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the green sheet is continuously conveyed together with the base. ### Claim 4 (depends on 3) The manufacturing method of a rare-earth permanent magnet according to claim 3, wherein, in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the green sheet conveyed together with the base is made to pass through a solenoid charged with electric current. ### Claim 5 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein: the green sheet has a long sheet-like shape; and in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the magnetic field is applied in an in-plane and machine direction of the green sheet. ### Claim 6 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein: the green sheet has a long sheet-like shape; and in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the magnetic field is applied in an in-plane and transverse direction of the green sheet. ### Claim 7 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein, in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the magnetic field is applied in a direction perpendicular to a plane of the green sheet. ### Claim 8 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein, before the step of sintering the green sheet, the binder is decomposed and removed from the green sheet by holding the green sheet for a predetermined length of time at binder decomposition temperature in a non-oxidizing atmosphere. ### Claim 9 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein: the binder is a thermoplastic resin made of a polymer or a copolymer consisting of one or more kinds of monomers selectable from possible monomers expressed with a general formula (1): wherein R1 and R2 represent a hydrogen atom, a lower alkyl group, a phenyl group or a vinyl group. ### Claim 10 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein the binder comprises: polyisobutylene; or a styrene-isoprene copolymer. ### Claim 11 (depends on 1) The manufacturing method of a rare-earth permanent magnet according to claim 1, wherein, in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the green sheet is heated by a heating device having a heat carrier as a heat source. ### Claim 12 (depends on 11) The manufacturing method of a rare-earth permanent magnet according to claim 11, wherein the green sheet is heated by the heating device through a heater element inside which the heat carrier heated to a predetermined temperature is circulated so as to heat the heater element. ### Claim 13 (depends on 12) The manufacturing method of a rare-earth permanent magnet according to claim 12, wherein the heater element is arranged making direct contact with or having a predetermined clearance from the green sheet. ### Claim 14 (depends on 11) The manufacturing method of a rare-earth permanent magnet according to claim 11, wherein the heat carrier is silicone oil. ### Claim 15 (depends on 4) The manufacturing method of a rare-earth permanent magnet according to claim 4, wherein, in the step of heating the green sheet and simultaneously/subsequently applying a magnetic field, the green sheet is heated by a heating device having a heat carrier as a heat source, and the heating device is arranged inside the solenoid. ### Claim 16 A rare-earth permanent magnet manufactured through steps of: milling magnet material into magnet powder; preparing a mixture of the magnet powder and a binder; obtaining a green sheet through thermally melting and forming the mixture into a sheet-like shape; heating the green sheet and simultaneously/subsequently applying a magnetic field to the heated green sheet for magnetic field orientation; and sintering the green sheet subjected to the magnetic field orientation.