Methods of producing bonded magnet and compound for bonded magnets

A method of preparing a bonded magnet, the method comprising:

• coating a magnetic material having an average particle size of 10 μm or less with a thermosetting resin and a curing agent at a ratio of the equivalent weight of the curing agent to the equivalent weight of the thermosetting resin of 2.2 or higher and 10 or lower to obtain a coated material;
• granulating the coated material by compression to obtain a granulated product;
• milling the granulated product to obtain a milled product;
• the method either comprising heat curing the granulated product between the granulation and the milling to obtain a cured product, or comprising heat curing the milled product to obtain a cured product;
• surface treating the cured product with a silane coupling agent to obtain a compound for bonded magnets so that the silane coupling agent exists on a surface of the cured product;
• orientation injection molding the compound for bonded magnets to obtain a molded product;
• and
• magnetizing the molded product in a magnetizing field of 25 kOe or higher.

A method of preparing a compound for bonded magnets, the method comprising:

• coating a magnetic material having an average particle size of 10 μm or less with a thermosetting resin and a curing agent at a ratio of the equivalent weight of the curing agent to the equivalent weight of the thermosetting resin of 2.2 or higher and 11.09 or lower to obtain a coated material;
• granulating the coated material by compression to obtain a granulated product;
• milling the granulated product to obtain a milled product;
• the method either comprising heat curing the granulated product between the granulation and the milling to obtain a cured product, or comprising heat curing the milled product to obtain a cured product;
• and
• surface treating the cured product with a silane coupling agent to obtain a compound for bonded magnets so that the silane coupling agent exists on a surface of the cured product.