A resin composition including: a magnetic fluid that includes magnetic particles, a dispersant, and a dispersion medium; and a resin or precursor thereof that includes, in a molecule thereof, at least one partial structure selected from the group consisting of a diene skeleton, a silicone skeleton, a urethane skeleton, a 4- to 7-membered ring lactone skeleton, an alkyl group having from 6 to 30 carbon atoms and an alkylene group having from 6 to 30 carbon atoms, a production method thereof, a resin composition molded body obtained by using the resin composition, and a production method thereof.

A forming method of a composite magnetic sheet. The forming method comprises a preparing step, a forming step and a heat-treating step. In the preparing step, magnetic slurry is prepared by mixing at least a soft magnetic powder having a flat shape, a first resin having a solid component and a second resin having a solid component, weight loss of the solid component of the first resin being 4.0% or less at 220° C., weight loss of the solid component of the second resin being 5.0% or more at 220° C. In the forming step, the magnetic slurry is formed into an intermediate body having a sheet-like shape. In the heat-treating step, the intermediate body is heat-treated at a heat-treatment temperature between 220° C. and 400° C. (both inclusive).

A forming method of a composite magnetic sheet. The forming method comprises a preparing step, a forming step and a heat-treating step. In the preparing step, magnetic slurry is prepared by mixing at least a soft magnetic powder having a flat shape, a first resin having a solid component and a second resin having a solid component, weight loss of the solid component of the first resin being 4.0% or less at 220° C., weight loss of the solid component of the second resin being 5.0% or more at 220° C. In the forming step, the magnetic slurry is formed into an intermediate body having a sheet-like shape. In the heat-treating step, the intermediate body is heat-treated at a heat-treatment temperature between 220° C. and 400° C. (both inclusive).

The present invention provides a magnetic multilayer pigment flake and a magnetic coating composition that are relatively safe for human health and the environment. The pigment flake includes one or more magnetic layers of a magnetic alloy and one or more dielectric layers of a dielectric material. The magnetic alloy is an iron-chromium alloy or an iron-chromium-aluminum alloy, having a substantially nickel-free composition. The coating composition includes a plurality of the pigment flakes disposed in a binder medium.

The present invention provides a magnetic multilayer pigment flake and a magnetic coating composition that are relatively safe for human health and the environment. The pigment flake includes one or more magnetic layers of a magnetic alloy and one or more dielectric layers of a dielectric material. The magnetic alloy is an iron-chromium alloy or an iron-chromium-aluminum alloy, having a substantially nickel-free composition. The coating composition includes a plurality of the pigment flakes disposed in a binder medium.

An object of the present invention is to provide a composition that can form a magnetic particle-containing film having excellent magnetic permeability and excellent acid resistance, and has excellent sedimentation stability. Another object of the present invention is to provide a magnetic particle-containing film that relates to the composition, and an electronic component that includes the magnetic particle-containing film.

The composition according to an embodiment of the present invention contains magnetic particles that contain 70% to 90% by mass of Fe atoms and have a crystal structure of Fe, an average particle diameter of 2 to 30 μm, and an aspect ratio less than 8, and a rheology control agent.

An upper end portion and a lower end portion of a second magnetic portion of a coil component are further away from a coil than when a third part and a fifth part are not present. For this reason, a magnetic flux is unlikely to be concentrated in the upper end portion and the lower end portion of the second magnetic portion, so that magnetic saturation is unlikely to occur. Therefore, improvement of direct current superimposition characteristics is realized in the coil component.

A field magnet manufacturing method where a bonded magnet's inner surface press-fitted in a yoke has a certain accuracy irrespective of the accuracy of the yoke's outer circumferential surface. A cylindrical bonded magnet from binding magnet particles with a thermosetting resin is fixed in a tubular yoke of magnetic material. The method includes reheating and softening the bonded magnet after thermal curing; and press-fitting in the bonded magnet after the softening step from a tapered portion on one end side of the yoke to press the bonded magnet's outer circumferential surface against the yoke's inner surface. The press-fitting includes feeding the bonded magnet relatively into the yoke while allowing a relative posture variation between the bonded magnet and the yoke so the bonded magnet's inner surface to be remolded into a shape along the inner surface of the yoke exhibits almost the same accuracy as the yoke's inner surface.

A field magnet manufacturing method where a bonded magnet's inner surface press-fitted in a yoke has a certain accuracy irrespective of the accuracy of the yoke's outer circumferential surface. A cylindrical bonded magnet from binding magnet particles with a thermosetting resin is fixed in a tubular yoke of magnetic material. The method includes reheating and softening the bonded magnet after thermal curing; and press-fitting in the bonded magnet after the softening step from a tapered portion on one end side of the yoke to press the bonded magnet's outer circumferential surface against the yoke's inner surface. The press-fitting includes feeding the bonded magnet relatively into the yoke while allowing a relative posture variation between the bonded magnet and the yoke so the bonded magnet's inner surface to be remolded into a shape along the inner surface of the yoke exhibits almost the same accuracy as the yoke's inner surface.

In a coil component, a second magnetic portion disposed in the vicinity of a coil is designed to have a higher proportion of Fe than a metal magnetic powder-containing resin constituting a first magnetic portion. Therefore, a magnetic flux of the coil flows smoothly. Although the second magnetic portion has a relatively lower withstand voltage than the first magnetic portion, since the second magnetic portion is surrounded by the first magnetic portion, it is not exposed on an outer surface of a magnetic body. For this reason, a situation in which the coil and external terminal electrodes are short-circuited with the second magnetic portion therebetween is effectively curbed, and short-circuiting between the coil and the external terminal electrodes can be curbed.