Method for producing magnetic molded body and method for producing anisotropic bonded magnet

Abstract

A method for manufacturing a magnetic molded body according to the present invention comprises: a supply step for supplying a composite containing a magnet powder, a thermosetting resin, and a wax into a mold; a molding step for compressing the composite in the mold while applying a magnetic field to the composite in the mold heated at the molding temperature Tm, thereby forming a molded body from the composite and removing the wax from the molded body; a demagnetizing step for demagnetizing the molded body after the molding step; and a heat curing step in which, after the demagnetizing step, the molded body is heated at a temperature equal to or higher than the heat curing temperature of the thermosetting resin, thereby obtaining a magnetic molded body. The magnet powder contains an Sm-Fe-N-based permanent magnet. The molding temperature Tm is not less than the dropping point of the wax and less than the thermosetting temperature of the thermosetting resin.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a magnetic formed body and a method for manufacturing an anisotropic bonded magnet. Background Art

[0002] Compared with other rare earth magnets such as Sm-Fe-N permanent magnets (samarium-iron-nitrogen permanent magnets) and Nd-Fe-B permanent magnets (neodymium-iron-boron permanent magnets), Sm-Fe-N permanent magnets can be manufactured from inexpensive raw materials and have excellent magnetic properties. On the other hand, since the crystal structure of Sm-Fe-N permanent magnets easily deteriorates at high temperatures (about 500°C), it is difficult to manufacture sintered magnets from Sm-Fe-N permanent magnets. Therefore, Sm-Fe-N permanent magnets are used as raw materials for anisotropic bonded magnets that can be manufactured by heating (thermal curing of a thermosetting resin mixed with magnet powder) at a low temperature that maintains the crystal structure.

[0003] As a raw material for an anisotropic bonded magnet, a composite including magnet powder (a plurality of magnet particles formed from a permanent magnet) and a thermosetting resin is used. In the manufacture of an anisotropic bonded magnet, the composite is supplied into a mold. While applying a magnetic field generated by a coil to the composite in the mold, the composite is compressed with the mold, whereby a formed body is formed from the composite. Each magnet particle (magnetic domain in each magnet particle) in the formed body is magnetized and oriented along the magnetic field. The formed body is demagnetized, and the demagnetized formed body is cured by heating. By magnetizing the cured formed body, an anisotropic bonded magnet is obtained. The residual magnetic flux density (Br), which is one of the important magnetic properties of an anisotropic bonded magnet, is increased by the orientation of the magnet powder in the formed body and the increase in the filling rate of the magnet powder in the formed body.

[0004] In addition to the above manufacturing method, various manufacturing methods using Sm-Fe-N permanent magnets are also known. For example, Patent Document 1 below discloses a method for manufacturing a magnet formed body having a high residual magnetic flux density by cold pressing and forming Sm-Fe-N magnet powder containing a metal binder (such as Zn and Cu) under high pressure (1 to 5 GPa). Patent Document 2 below discloses a method for manufacturing a bonded magnet from a composite including Sm-Fe-N magnet powder and a low-viscosity thermosetting resin. Patent Document 3 below discloses a composite including Sm-Fe-N magnet powder, epoxy resin, and wax as a raw material for a bonded magnet.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-82175

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2021-127515

[0009] Patent Document 3: WO 2019 / 106813

[0010] Patent Document 4: Japanese Unexamined Patent Application Publication No. 2019-48948 Summary of the Invention

[0011] Technical Problem to be Solved by the Invention

[0012] Magnetic powder formed of an Sm-Fe-N-based permanent magnet can have anisotropy. That is, each magnetic particle (magnetic domain in each magnetic particle) constituting the magnetic powder formed of the Sm-Fe-N-based permanent magnet can have an easy magnetization axis (crystal axis) extending in one direction. Therefore, when the magnetic powder is formed of an Sm-Fe-N-based permanent magnet, during the compression process of the composite to which a magnetic field is applied, each magnetic particle in the composite rotates due to the magnetic field, and the easy magnetization axes of each magnetic particle (each magnetic domain) are easily oriented along the direction of the magnetic field. As a result, an anisotropic bonded magnet having a high residual magnetic flux density can be obtained. However, the higher the viscosity of the thermosetting resin in the composite, the more difficult it is for each magnetic particle in the composite to rotate due to the magnetic field, and the more difficult it is for the easy magnetization axes of each magnetic particle (each magnetic domain) to be oriented along the direction of the magnetic field. Even when the viscosity of the thermosetting resin in the composite is high, each magnetic particle in the composite rotates due to the magnetic field by using a pulsed magnetic field having a high intensity. However, in order to generate a pulsed magnetic field, a large magnetic field generating device is required. On the other hand, when a static magnetic field (continuous and constant magnetic field) generated by a small magnetic field generating device is used, it is difficult to sufficiently orient the easy magnetization axes of each magnetic particle in the composite along the magnetic field.

[0013] When the composite contains wax in addition to the magnetic powder and the thermosetting resin, each magnetic particle in the composite easily rotates due to the lubricity of the wax. However, unlike the thermosetting resin (adhesive), wax does not cure by heating and does not bond magnetic particles to each other. Therefore, as the content of wax in the composite increases, the mechanical strength of the formed body formed from the composite decreases, and the mechanical strength of the anisotropic bonded magnet also decreases. For example, the mechanical strength can be referred to as crushing strength or radial crushing strength.

[0014] An object of one aspect of the present invention is to provide a method for manufacturing a magnetic formed body for manufacturing an anisotropic bonded magnet having excellent residual magnetic flux density and mechanical strength, and a method for manufacturing an anisotropic bonded magnet having excellent residual magnetic flux density and mechanical strength.

[0015] Means for Solving Technical Problems

[0016] For example, one aspect of the present invention relates to a method for manufacturing a magnetic compact described in any one of [1] to [8] below and a method for manufacturing an anisotropic bonded magnet described in [9] below.

[0017] [1] A method for manufacturing a magnetic compact, comprising: a supplying step of supplying a composite containing magnet powder, a thermosetting resin, and wax into a mold; a molding step of compressing the composite in the mold while applying a magnetic field to the composite in the mold heated to a molding temperature Tm, thereby forming a compact from the composite and removing the wax from the compact; a demagnetizing step of demagnetizing the compact after the molding step; and a thermal curing step of heating the compact at a temperature equal to or higher than the thermal curing temperature of the thermosetting resin after the demagnetizing step, thereby obtaining a magnetic compact from the compact. The magnet powder contains an Sm-Fe-N based permanent magnet, and the molding temperature Tm is equal to or higher than the dropping point of the wax and lower than the thermal curing temperature of the thermosetting resin.

[0018] [2] The method for manufacturing a magnetic compact according to [1], wherein the molding step includes a first pressing step and a second pressing step immediately following the first pressing step.

[0019] In the first pressing step, the pressure applied to the composite in the mold heated to the molding temperature Tm is maintained at a first pressure P1.

[0020] In the second pressing step, the pressure applied to the composite in the mold heated to the molding temperature Tm is maintained at a second pressure P2.

[0021] The second pressure P2 is higher than the first pressure P1.

[0022] In the second pressing step, the wax is removed from the compact.

[0023] [3] The method for manufacturing a magnetic compact according to [1], wherein in the molding step, the wax is removed from the compact by continuously increasing the pressure applied to the composite in the mold heated to the molding temperature Tm to the second pressure P2.

[0024] [4] The method for manufacturing a magnetic formed body according to any one of [1] to [3] further includes: a cooling step of cooling a mold accommodating the formed body from a molding temperature Tm to a temperature lower than the dropping point.

[0025] Immediately after the molding step, the cooling step is carried out.

[0026] A demagnetization step is carried out after the cooling step.

[0027] [5] The method for manufacturing a magnetic formed body according to any one of [1] to [4], wherein a clearance is formed in the mold.

[0028] The viscosity of the wax at the molding temperature Tm is lower than the viscosity of the thermosetting resin at the molding temperature Tm, and in the molding step, the wax removed from the formed body is discharged out of the mold through the clearance.

[0029] [6] The method for manufacturing a magnetic formed body according to any one of [1] to [5], wherein the sum of the mass of the magnet powder and the mass of the thermosetting resin is represented as M1.

[0030] The mass of the wax in the composite is represented as M2.

[0031] (M2 / M1)×100 is 2 or more and 10 or less.

[0032] [7] The method for manufacturing a magnetic formed body according to any one of [1] to [6], wherein the thermosetting resin contains at least one resin selected from the group consisting of epoxy resin, maleimide compound, polyimide, polyamide, and polyamideimide.

[0033] [8] The method for manufacturing a magnetic formed body according to any one of [1] to [7], wherein the wax contains montanate.

[0034] [9] A method for manufacturing an anisotropic bond magnet, which includes the method for manufacturing a magnetic formed body according to any one of [1] to [8].

[0035] The method for manufacturing the anisotropic bond magnet further includes a magnetizing step of obtaining the anisotropic bond magnet by magnetizing the magnetic formed body.

[0036] That is, the method for manufacturing an anisotropic bonded magnet according to one aspect of the present invention includes: a supply step of supplying a composite material containing magnet powder, a thermosetting resin, and wax into a mold; a molding step of compressing the composite material in the mold while applying a magnetic field to the composite material in the mold heated to a molding temperature Tm, thereby forming a formed body from the composite material and removing the wax from the formed body; a demagnetization step of demagnetizing the formed body after the molding step; a thermosetting step of heating the formed body at a temperature equal to or higher than the thermosetting temperature of the thermosetting resin after the demagnetization step, thereby obtaining a magnetic formed body from the formed body; and a magnetization step of magnetizing the magnetic formed body to obtain an anisotropic bonded magnet. The magnet powder contains an Sm-Fe-N-based permanent magnet, and the molding temperature Tm is equal to or higher than the dropping point of the wax and lower than the thermosetting temperature of the thermosetting resin.

[0037] Advantages of the Invention

[0038] According to one aspect of the present invention, there can be provided a method for manufacturing a magnetic formed body for manufacturing an anisotropic bonded magnet having excellent residual magnetic flux density and mechanical strength, and a method for manufacturing an anisotropic bonded magnet having excellent residual magnetic flux density and mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 (a) in Figure 1 and (b) in are schematic cross-sectional views of a manufacturing apparatus used in the method for manufacturing a magnetic formed body according to an embodiment of the present invention. Figure 1 (a) in Figure 1 and the cross section shown in (b) pass through all of a pair of punches, a die, a composite material, and a pair of coils, and are parallel to the direction (pressing direction) of the pressure applied to the composite material by the pair of punches.

[0040] Figure 2 is a graph showing the change in the mold temperature over time during the molding step and the change in all the pressures acting on the composite material in the mold over time during the molding step.

[0041] Figure 3 is another graph showing the change in the mold temperature over time during the molding step and the change in all the pressures acting on the composite material in the mold over time during the molding step.

[0042] Figure 4 is a schematic cross-sectional view of a magnetic formed body (or anisotropic bonded magnet) according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals are given to the same components. The present invention is not limited to the following embodiments.Figure 1 in (a) of Figure 1 in (b) of Figure 4 The X, Y, and Z shown represent three mutually orthogonal coordinate axes. The directions of the X-axis, Y-axis, and Z-axis are each the same as those in Figure 1 in (a) of Figure 1 in (b) of Figure 4 the same.

[0044] (Manufacturing apparatus)

[0045] Figure 1 in (a) of Figure 1 in (b) of represent a schematic cross-section of the manufacturing apparatus 10 (forming apparatus) used in the method for manufacturing the magnetic formed body according to the present embodiment.

[0046] The manufacturing apparatus 10 includes: a pair of punches (a first punch p1 and a second punch p2) facing each other; and a cylindrical die d1 into which the pair of punches is inserted. A first opening is formed on the end face of the die d1 opposite to the first punch p1, and the first punch p1 is inserted into the first opening. A second opening is formed on the end face of the die d1 opposite to the second punch p2, and the second punch p2 is inserted into the second opening. The second punch p2 inserted into the die d1 and the die d1 form a cavity (concave type). The first punch p1 functions as a core (convex type). That is, a set of molds is constituted by a pair of punches (a first punch p1 and a second punch p2) facing each other and a cylindrical die d1 into which the pair of punches is inserted.

[0047] The composite 2 as a raw material for the magnetic formed body and the anisotropic bonded magnet is supplied into the cavity formed by the second punch p2 and the die d1. (Refer to Figure 1 (a) of.) The composite 2 in the cavity is clamped between the first punch p1 and the second punch p2, and is pressurized and compressed by the first punch p1 and the second punch p2. (Refer to Figure 1 (b) of.) The directions (pressurizing directions) of the pressures applied by the first punch p1 and the second punch p2 to the composite 2 are parallel to the Z-axis. In the present embodiment, the "pressure acting on the composite in the mold" refers to the pressures applied by the first punch p1 and the second punch p2 to the composite 2 respectively. The "pressure acting on the composite in the mold" is denoted as the forming pressure P.

[0048] A gap 6 is formed in the mold. For example, the gap 6 is formed between the side surfaces of the first punch p1 and the second punch p2 and the inner wall of the die d1. Due to the gap 6, the side surfaces of the first punch p1 and the second punch p2 easily slide on the inner wall of the die d1. As will be described later, a part or all of the wax 4 in the composite 2 is discharged to the outside of the mold (cavity) through the gap 6 during the molding process. The width of the gap 6 is small enough that the magnet powder and the thermosetting resin in the composite 2 do not discharge to the outside of the mold through the gap 6. For example, the width of the gap 6 can be smaller than the particle size of each magnet particle constituting the magnet powder. As long as the inside of the mold (cavity) communicates with the outside of the mold through the gap 6, the position where the gap 6 is formed in the mold is not limited.

[0049] The dimensions and shapes of the first punch p1, the second punch p2, and the die d1 are not limited. For example, the dimensions and shapes of the first punch p1, the second punch p2, and the die d1 can be changed according to the desired dimensions and shapes of the magnetic formed body or the anisotropic bonded magnet. The compositions of the first punch p1, the second punch p2, and the die d1 are not limited. For example, the first punch p1, the second punch p2, and the die d1 can be metals that have sufficient mechanical strength as molds, respectively.

[0050] The manufacturing apparatus 10 includes a pair of coils (the first coil c1 and the second coil c2). The die d1 and the composite 2 in the die d1 are disposed between the pair of coils (the first coil c1 and the second coil c2). The first punch p1 and the second punch p2 do not penetrate the inside of each of the pair of coils (the first coil c1 and the second coil c2).

[0051] The manufacturing apparatus 10 further includes a power supply mechanism. The power supply mechanism is electrically connected to the first coil c1 and the second coil c2, respectively. Through the power supply mechanism, the direction and absolute value of the first current generated in the first coil c1 and the direction and absolute value of the second current generated in the second coil c2 are freely controlled. The power supply mechanism is omitted in each figure.

[0052] The magnetic field H can be synthesized by the magnetic field generated in the first coil c1 and the magnetic field generated in the second coil c2, and the synthesized magnetic field H can also be applied to the composite 2 in the die d1. The magnetic field H generated by only one of the first coil c1 and the second coil c2 can also be applied to the composite 2 in the die d1. The details of the magnetic field H will be described later.

[0053] The central axes of the first coil c1 and the second coil c2 coincide with each other and are parallel to the X-axis. The magnetic field H generated by the first coil c1 and the second coil c2 is also parallel to the X-axis. The direction of the magnetic field H is perpendicular to the pressing direction. That is, the magnetic field H perpendicular to the pressing direction is applied to the composite. However, the direction of the magnetic field H is not limited. The direction of the magnetic field H can be changed by changing the respective configurations of the first coil c1 and the second coil c2. For example, the first punch p1 can pass through the inside of the first coil c1, the second punch p2 can pass through the inside of the second coil c2, the die d1 can be disposed between the first coil c1 and the second coil c2, the central axes of the first coil c1 and the second coil c2 can coincide with each other, and the central axes of the first coil c1 and the second coil c2 can be parallel to the pressing direction. As a result, the magnetic field H parallel to the pressing direction can be applied to the composite 2.

[0054] As long as the first coil c1 and the second coil c2 are conductors respectively, the composition of each of the first coil c1 and the second coil c2 is not limited. The first coil c1 and the second coil c2 can be hollow coils respectively. An iron core (soft iron) can also be provided inside each of the first coil c1 and the second coil c2. The inner diameters and the number of turns (number of coils) of each of the first coil c1 and the second coil c2 are not limited. The inner diameters of the first coil c1 and the second coil c2 can be the same as each other. The inner diameters of the first coil c1 and the second coil c2 can also be different from each other. The number of turns of the first coil c1 and the second coil c2 can be the same as each other. The number of turns of the first coil c1 and the second coil c2 can also be different from each other.

[0055] (Method for manufacturing a magnetic formed body and method for manufacturing an anisotropic bonded magnet)

[0056] The method for manufacturing a magnetic formed body according to the present embodiment includes a supply step, a molding step, (a cooling step,) a demagnetization step, and a thermosetting step. The method for manufacturing an anisotropic bonded magnet according to the present embodiment includes the method for manufacturing a magnetic formed body, and further includes a magnetization step implemented in the thermosetting step. That is, the method for manufacturing an anisotropic bonded magnet according to the present embodiment includes, in addition to the supply step, the molding step, (the cooling step,) the demagnetization step, and the thermosetting step, a magnetization step. Hereinafter, the detailed content of each step will be described.

[0057] "Magnetic molded body" refers to a cured product containing magnet powder and a thermosetting resin, in which the easy magnetization axes in each magnet particle (each magnetic domain in each magnet particle) constituting the magnet powder are oriented in a desired direction (the direction of the magnetic field in the molding process). "Anisotropic bonded magnet" is a magnet that contains a cured product of magnet powder and a thermosetting resin, in which the easy magnetization axes (easy magnetization axis) in each magnet particle (each magnetic domain in each magnet particle) constituting the magnet powder are oriented in a desired direction (the direction of the magnetic field in the molding process), each magnet particle is magnetized in the desired direction, and the entire magnet is magnetized in the desired direction.

[0058] <Supply process>

[0059] In the supply process, a composite 2 containing magnet powder, a thermosetting resin, and wax is supplied into the above-mentioned mold (cavity). (Refer to (a) in Figure 1 .) The magnet powder can be referred to as a plurality of magnet particles formed of a permanent magnet. The magnet powder contains an Sm-Fe-N-based permanent magnet. The magnet powder can be formed only of an Sm-Fe-N-based permanent magnet. The details of the magnet powder will be described later. The temperature of the composite itself supplied into the mold can be room temperature. At room temperature, the composite 2 can be a solid. For example, the composite 2 can be powder. Instead of the composite 2, a tablet formed of the composite 2 can also be supplied into the mold.

[0060] <Molding process>

[0061] In the molding process, while applying a magnetic field H to the composite 2 in the mold heated to the molding temperature Tm, the composite 2 in the mold is compressed. (Refer to (b) in Figure 1 .) Since the molding temperature Tm is above the dropping point of the wax, the wax in the composite 2 is liquefied. Due to the lubricity of the liquefied wax, the magnet particles easily slide relative to each other, the magnet particles magnetized by the magnetic field H easily rotate, and the easy magnetization axes of the magnetic domains in each magnet particle are oriented along the magnetic field H. In other words, each magnet particle 3 is oriented such that the magnetization direction m of each magnet particle 3 is substantially parallel to the magnetic field H. (Refer to Figure 4.) When each magnetic particle 3 is a single crystal grain (single magnetic domain), the magnetization direction m of each magnetic particle 3 is the same as the direction in which the easy magnetization axis of each magnetic particle extends. Since the molding temperature Tm is lower than the thermosetting temperature of the thermosetting resin 5, the thermosetting of the thermosetting resin is suppressed in the molding process, and the rotation and orientation of each magnetic particle 3 driven by the magnetic field H are not easily hindered by the thermosetting of the thermosetting resin 5. As the composite 2 is compressed, a molded body 2A containing magnetic powder and thermosetting resin (uncured material) oriented along the magnetic field H is formed. The magnetization direction M of the entire molded body 2A before demagnetization is substantially parallel to the direction of the magnetic field H applied to the composite 2 in the molding process.

[0062] As described above, due to the lubricity of the wax in the molding process, a molded body 2A with excellent orientation of magnetic powder can be obtained. The state of the magnetic powder orientation is also maintained in the magnetic molded body obtained by demagnetization and thermosetting of the molded body 2A. Therefore, the anisotropic bonded magnet obtained by magnetizing the magnetic molded body can have a high residual magnetic flux density caused by the excellent orientation of the magnetic powder. Moreover, due to the compression of the composite 2 in the molding process (i.e., the increase in the filling rate of the magnetic powder in the molded body 2A), the residual magnetic flux density of the anisotropic bonded magnet increases.

[0063] According to the present embodiment, even when the viscosity of the thermosetting resin is high and the thermosetting resin hinders the rotation and orientation of the magnetic particles, each magnetic particle can rotate and orient due to the lubricity of the liquefied wax. Therefore, according to the present embodiment, it is possible to manufacture an anisotropic bonded magnet using a thermosetting resin (for example, a heat-resistant thermosetting resin with high viscosity) that has been difficult to use for anisotropic bonded magnets in the past. For example, the heat-resistant thermosetting resin may be at least one resin selected from the group consisting of epoxy resin, maleimide compound, polyimide, polyamide, and polyamideimide. The details of the thermosetting resin will be described later.

[0064] As described above, due to the wax, the residual flux density of the anisotropic bonded magnet increases. However, unlike the thermosetting resin (adhesive), the wax does not cure and does not bond the magnet particles to each other. Therefore, due to the wax remaining in the molded body 2A, the mechanical strength of the molded body 2A is reduced. The wax derived from the composite 2 remains in the magnetic molded body obtained from the molded body 2A, whereby the mechanical strength of the magnetic molded body is also reduced. The wax derived from the composite 2 remains in the anisotropic bonded magnet obtained from the magnetic molded body, whereby the mechanical strength of the anisotropic bonded magnet is also reduced. However, in the molding process, the composite 2 is compressed while heating the mold at a molding temperature Tm equal to or higher than the dropping point of the wax. As a result, during the formation process of the molded body 2A (the compression process of the composite 2), a part or all of the liquefied wax in the molded body 2A oozes out from the molded body 2A, and the wax is removed from the molded body 2A. Therefore, according to the present embodiment, it is possible to suppress a decrease in the mechanical strength of the anisotropic bonded magnet caused by the wax that contributes to an increase in the residual flux density of the anisotropic bonded magnet. That is, according to the present embodiment, it is possible to achieve both a high residual flux density and a high mechanical strength.

[0065] In the molding process, the wax 4 removed from the molded body 2A is discharged to the outside of the mold through the gap 6 formed in the mold. (Refer to Figure 1 (b) in the figure.) The molding temperature Tm is equal to or higher than the dropping point of the wax and lower than the thermosetting temperature of the thermosetting resin. Therefore, the viscosity of the wax at the molding temperature Tm is lower than the viscosity of the thermosetting resin at the molding temperature Tm, the wax is more easily flowable than the thermosetting resin at the molding temperature Tm, and the wax and the thermosetting resin are not easily miscible at the molding temperature Tm. As a result, the wax 4 is easily separated from the thermosetting resin in the molding process, and only the wax 4 is selectively removed from the molded body 2A, and only the wax 4 is easily selectively discharged to the outside of the mold through the gap 6. On the other hand, the thermosetting resin is not easily removed from the molded body 2A, and the thermosetting resin is not easily discharged to the outside of the mold through the gap 6.

[0066] The dropping point of the wax is the temperature at which the wax starts to liquefy by heating. For example, the dropping point of the wax is the temperature of the wax at the moment when the wax in a container having an opening with a specified inner diameter starts to liquefy by heating and the liquefied wax starts to drip from the opening. For example, the dropping point of the wax can be measured according to JIS (Japanese Industrial Standards) K 2220 or ASTM (America Society for Testing and Materials) standards D-566 and D-2265.

[0067] The dropping point of the wax is a value depending on the composition of the wax and is not limited. The thermosetting temperature of the thermosetting resin is a value depending on the composition of the thermosetting resin and is not limited. The molding temperature Tm is a value depending on the combination of the wax and the thermosetting resin and is not limited. For example, the molding temperature Tm is 60°C or higher and 150°C or lower, preferably 70°C or higher and 110°C or lower, and more preferably 80°C or higher and 100°C or lower.

[0068] The molding process may include a first pressing process and a second pressing process immediately following the first pressing process. As Figure 2 shown, in the first pressing process, the pressure (molding pressure P) acting on the composite material in the mold heated to the molding temperature Tm continuously increases from 0 MPa to a first pressure P1 (unit: MPa) and is maintained at the first pressure P1 for a specified time. As Figure 2 shown, in the second pressing process, the pressure (molding pressure P) acting on the composite material in the mold heated to the molding temperature Tm continuously increases from the first pressure P1 to a second pressure P2 (unit: MPa) and is maintained at the second pressure P2 for a specified time. That is, the second pressure P2 is higher than the first pressure P1. By pressing the composite material with a relatively low first pressure P1 in the first pressing process, excessive compression of the composite material is suppressed, and friction or contact between the respective magnet particles is suppressed. Each magnet particle in the composite material is easily rotated, and each magnet particle is easily oriented along the magnetic field. In the second pressing process, the formed body (composite material) is pressed with a relatively high second pressure P2, whereby the wax is easily removed from the formed body.

[0069] For example, the first pressure P1 may be greater than 0 MPa and less than 500 MPa. For example, the second pressure P2 may be 500 MPa or higher and 2000 MPa or lower, preferably 700 MPa or higher and 2000 MPa or lower, and more preferably 980 MPa or higher and 2000 MPa or lower. The lower the first pressure P1, the easier it is to suppress excessive compression of the composite material, the easier it is for each magnet particle in the composite material to rotate, and the easier it is for the magnetization directions of the respective magnet particles to be oriented substantially parallel to the magnetic field. The higher the second pressure P2, the easier it is to compress the formed body (composite material), and the easier it is to remove the wax from the formed body.

[0070] As Figure 3 shown, in the molding process, the wax can be removed from the formed body by continuously increasing the pressure (molding pressure P) acting on the composite material in the mold heated to the molding temperature Tm from 0 MPa to the second pressure P2. In Figure 3 the shown molding process, the molding pressure P may also be maintained at the second pressure P2 for a specified time.

[0071] The total mass of the magnet powder and the mass of the thermosetting resin is represented as M1 (unit: g). The mass of the wax in the composite is represented as M2 (unit: g). (M2 / M1)×100 can be 2 or more and 10 or less, 2.5 or more and 8 or less, 2 or more and 5 or less, 2.0 or more and 4.0 or less. When (M2 / M1)×100 is 2 or more, due to the lubricity of the wax 4, each magnet particle 3 rotates easily, and each magnet particle 3 easily aligns along the magnetic field H. When (M2 / M1)×100 is 10 or less, in the molding process, almost all of the wax is easily removed from the molded body, the wax hardly remains in the anisotropic bonded magnet, and the anisotropic bonded magnet easily has high mechanical strength. For example, when a magnetic molded body and an anisotropic bonded magnet are manufactured from a composite in which (M2 / M1)×100 is 2 or more and 10 or less, the wax content in the magnetic molded body can be 0.0 mass% or more and 0.1 mass% or less, and the wax content in the anisotropic bonded magnet can also be 0.0 mass% or more and 0.1 mass% or less.

[0072] The mass M3 of the wax in the molded body (magnetic molded body) after the molding process is less than the mass M2 of the wax in the composite, and the mass of the wax removed from the molded body (composite) through the molding process is M2 - M3. On the other hand, in the molding process, the total mass M1 of the magnet powder and the thermosetting resin in the composite (molded body) remains substantially unchanged. Therefore, M2 - M3 is substantially equal to the difference between the mass of the composite supplied into the mold and the mass of the molded body after the molding process. That is, the wax content in the magnetic molded body (or in the anisotropic bonded magnet) can be calculated based on the difference between the mass of the composite supplied into the mold and the mass of the molded body after the molding process.

[0073] In the molding process, after the temperature of the heated mold reaches the molding temperature Tm, a magnetic field can be applied to the composite in the mold. As a result, due to the lubricity of the liquefied wax, the magnet particles easily slide relative to each other, each magnet particle rotates easily, and each magnet particle easily aligns along the magnetic field.

[0074] In the molding process, a magnetic field can be applied to the composite material in the mold simultaneously with the compression of the composite material in the mold. The application of the magnetic field to the composite material in the mold can start earlier than the compression of the composite material in the mold. When the application of the magnetic field to the composite material in the mold starts earlier than the compression of the composite material in the mold, in a state where the compression of the composite material is suppressed, each magnetic particle in the composite material is likely to rotate. As a result, each magnetic particle is likely to be oriented along the magnetic field. In the molding process, the application of the magnetic field to the composite material in the mold can be stopped at the moment when the molding pressure P starts to decrease. That is, the application of the magnetic field to the composite material in the mold can be stopped simultaneously with the end of the second pressing process. The application of the magnetic field to the composite material in the mold can be stopped simultaneously with the start of the second pressing process. That is, the application of the magnetic field to the composite material in the mold can be stopped at the moment when the molding pressure reaches the second pressure P2.

[0075] The magnetic field H can be a static magnetic field (continuous and constant magnetic field). The magnetic field H can be a pulsed magnetic field (magnetic field in a pulsed mode). The higher the intensity of the magnetic field H, the higher the orientation of the magnet powder in the formed body. The longer the time for applying the magnetic field H to the composite material in the mold, the higher the orientation of the magnet powder in the formed body. The more times the magnetic field H is applied to the composite material in the mold, the higher the orientation of the magnet powder in the formed body.

[0076] The intensity of the static magnetic field for manufacturing the anisotropic bonded magnet is lower than that of the pulsed magnetic field. When the magnetic field H is a static magnetic field, by applying the magnetic field H to the composite material in the mold for a sufficiently long time, each magnetic particle in the composite material is sufficiently oriented along the magnetic field. For example, the intensity of the static magnetic field can be 0.5 T (tesla) or more and 2.5 T or less, preferably 1.0 T or more and 2.5 T or less, more preferably 2.0 T or more and 2.5 T or less. For example, the time for applying the static magnetic field to the composite material in the mold can be 0.08 minutes or more and 4 minutes or less, preferably 0.5 minutes or more and 4 minutes or less, more preferably 1 minute or more and 4 minutes or less.

[0077] The pulsed magnetic field for manufacturing the anisotropic bonded magnet has a higher intensity than the static magnetic field. Since the pulsed magnetic field is generated instantaneously, the amount of heat generated by the current required to generate the pulsed magnetic field (Joule heat in the coil) can be suppressed. By instantaneously applying a pulsed magnetic field with a high intensity to the composite material in the mold, each magnetic particle in the composite material is instantaneously and sufficiently oriented along the magnetic field. Considering the limit of the intensity of the pulsed magnetic field that can be generated by a commercially available pulsed magnetic field generating device and the cost, the upper limit value of the intensity of the pulsed magnetic field is about 12 T. For example, the intensity of the pulsed magnetic field can be 4 T or more and 12 T or less or 8 T or more and 12 T or less. The number of times the pulsed magnetic field is applied to the composite material can be once or more. For example, a pulsed magnetic field with an intensity of 4 T or more can be applied to the composite material once or more.

[0078] <Cooling process>

[0079] As described above, the method for manufacturing a magnetic formed body may further include a cooling process. The cooling process immediately follows the above-mentioned forming process. The demagnetization process may be carried out after the cooling process. In the cooling process, the mold containing the formed body is cooled from the forming temperature Tm to a temperature lower than the dropping point of the wax (for example, room temperature). In the cooling process, it is not necessary to apply a magnetic field H to the formed body in the mold. However, in the cooling process, a magnetic field H may be applied to the formed body in the mold.

[0080] The thermosetting resin (uncured material) in the formed body is softened by the heating of the mold in the forming process. The softened thermosetting resin in the formed body is cured by the cooling process. When wax remains in the formed body during the forming process, the liquefied wax in the formed body is solidified by the cooling process. For these reasons, the mechanical strength of the formed body is increased in the cooling process, and deformation and breakage of the formed body in each process after the cooling process are suppressed. As a result, the mechanical strength of the finally obtained anisotropic bonded magnet is easily increased. When the demagnetization process is carried out before the thermosetting resin (uncured material) and wax in the formed body are sufficiently solidified, the positions and orientation directions of the respective magnet particles in the formed body are likely to change with the application of a magnetic field to the formed body in the demagnetization process, and the orientation of the magnet powder in the formed body may be impaired. That is, when the demagnetization process is carried out after the forming process without carrying out the cooling process, the orientation of the magnet powder in the formed body may be impaired in the demagnetization process.

[0081] For example, the method of cooling the mold containing the formed body may be natural cooling of the mold. As Figure 2 and Figure 3 shown, in the cooling process (the process in which the temperature T of the mold is reduced to room temperature), the forming pressure P may be gradually reduced from the second pressure P2 to 0 MPa. At the start time of the cooling process (the end time of the forming process), the forming pressure P may disappear instantaneously. That is, at the start time of the cooling process (the end time of the forming process), the forming pressure P may be instantaneously reduced from the second pressure P2 to 0 MPa.

[0082] <Demagnetization process>

[0083] The demagnetization process is carried out after the molding process. In the demagnetization process, the molded body is demagnetized by applying a magnetic field (reverse magnetic field) in the direction opposite to the magnetic field H used in the molding process to the molded body. For the above reasons, the demagnetization process can be carried out after the cooling process immediately following the molding process. The demagnetization process can be carried out simultaneously with the cooling process. That is, the molded body accommodated in the mold can be demagnetized by applying a reverse magnetic field in parallel with the cooling of the mold. After the molded body is demagnetized simultaneously with the cooling process, the molded body is taken out of the mold. The demagnetization process can be carried out by the above-mentioned manufacturing device 10 (molding device) used in the molding process. After the cooling process, the molded body taken out of the mold can be demagnetized by another magnetic field applying device.

[0084] <Thermosetting process>

[0085] The thermosetting process is carried out after the demagnetization process. In the thermosetting process, the molded body is heated to a temperature equal to or higher than the thermosetting temperature of the thermosetting resin. As a result, the thermosetting resin in the molded body is cured, and a magnetic molded body is obtained from the molded body. The magnet powder in the magnetic molded body is bonded to each other by the cured product of the thermosetting resin, and each magnet particle is fixed in the magnetic molded body. In the thermosetting process, a plurality of molded bodies that have undergone the demagnetization process can be heated together.

[0086] In the thermosetting process, the temperature of the molded body increases from room temperature to a temperature equal to or higher than the thermosetting temperature of the thermosetting resin. In the thermosetting process, at the moment before the temperature of the molded body reaches the thermosetting temperature, the thermosetting resin (and wax) in the molded body is softened, and the molded body itself is softened. The positions and orientations of the respective magnet particles in the softened molded body are not sufficiently fixed by the softened thermosetting resin. Assuming that the thermosetting process is carried out without performing the demagnetization process, due to the magnetic force possessed by the molded body itself, the positions and orientations of the respective magnet particles in the softened molded body change, and thus the orientation of the magnet powder in the molded body is impaired. As a result, it is difficult for the anisotropic bonded magnet to have a high residual magnetic flux density. For example, each magnet particle located near the surface of the softened molded body protrudes from the surface of the molded body along with the thermosetting resin (and wax). That is, one or more protrusions containing magnet particles and thermosetting resin are formed on the surface of the molded body. This is because, in the portion of the surface of the molded body that has not undergone the demagnetization process and has a high magnetic flux density, the magnetic force easily acts on the magnet particles located near the surface of the molded body.

[0087] <Magnetization process>

[0088] The magnetization process is carried out after the thermosetting process. In the magnetization process, a magnetic field in the same direction as the magnetic field H used in the molding process is applied to the magnetic molded body. As a result, the magnetic molded body is magnetized and becomes an anisotropic bonded magnet. As Figure 4As shown, the magnetization direction M of the entire anisotropic bonded magnet 2B is substantially parallel to the direction of the magnetic field H applied to the composite (formed body) in the forming process. In other words, the magnetization direction m of each magnet particle 3 in the anisotropic bonded magnet 2B is substantially parallel to the magnetic field H.

[0089] <Analysis Method>

[0090] In order to analyze and determine the respective compositions of the magnetic formed body and the anisotropic bonded magnet, samples obtained by pulverizing the magnetic formed body and the anisotropic bonded magnet can be analyzed. In order to retrospectively analyze and determine the composition of the composite itself from the magnetic formed body and the anisotropic bonded magnet, samples obtained by pulverizing the magnetic formed body and the anisotropic bonded magnet can be analyzed. Moreover, the samples obtained by pulverization are dissolved in an organic solvent, and the magnet powder constituting the sample can be separated from the resin composition dissolved in the organic solvent. The resin composition and the magnet powder separated from each other can be analyzed separately.

[0091] In the case of analyzing and determining the composition of the uncured composite, the composite can also be dissolved in an organic solvent, and the magnet powder can be separated from the resin composition dissolved in the organic solvent. The resin composition and the magnet powder separated from each other can be analyzed separately.

[0092] For example, each component (such as a thermosetting resin and wax) constituting the resin composition can be analyzed and determined by one or more analysis methods selected from the group consisting of infrared spectroscopy (IR), nuclear magnetic resonance (NMR), mass spectrometry (MS), gas chromatography (GC), and high-performance liquid chromatography (HPLC).

[0093] For example, the magnet powder can be analyzed and determined by one or more analysis methods selected from the group consisting of X-ray fluorescence analysis (XRF), inductively coupled plasma (ICP) emission spectroscopy, photoelectron spectroscopy (X-ray photoelectron spectroscopy; XPS), energy dispersive X-ray spectroscopy (EDS or EDX), and mass spectrometry.

[0094] The residual magnetic flux density Br1 of the magnetic formed body (or anisotropic bonded magnet) and the residual magnetic flux density Br2 of the magnet powder itself can satisfy the following mathematical formula 1.

[0095] Br1 = Br2 × (V2 / V1) × D (mathematical formula 1)

[0096] In mathematical formula 1, V1 is the volume of the entire magnetic formed body (or anisotropic bonded magnet). V2 in mathematical formula 1 is the volume of the magnet powder itself contained in the magnetic formed body (or anisotropic bonded magnet). V2 / V1 is equivalent to the filling rate of the magnet powder in the magnetic formed body (or anisotropic bonded magnet). D in mathematical formula 1 is the orientation degree of the magnet powder in the magnetic formed body (or anisotropic bonded magnet). According to the above mathematical formula 1, the orientation degree D is expressed as Br1 / {Br2 × (V2 / V1)}. That is, the orientation degree D can be determined based on the measurements of Br1, Br2, V1, and V2 respectively. A high orientation degree means that the easy magnetization axes in each magnet particle constituting the magnet powder contained in the magnetic formed body are oriented. In other words, a high orientation degree means that the magnetization directions of each magnet particle constituting the magnet powder contained in the anisotropic bonded magnet are oriented. For example, the orientation degree D (unit: %) of the magnet powder in the magnetic formed body (or anisotropic bonded magnet) can be 80% or more and 100% or less.

[0097] (Composite)

[0098] <Magnet Powder>

[0099] As described above, the magnet powder is a powder containing Sm-Fe-N-based permanent magnet (SmFeN powder). For example, the SmFeN powder can be a powder containing Sm2Fe 17 N3 (alloy) as the main phase. For example, at least a part of the SmFeN powder can be an anisotropic magnet powder containing Th2Zn-type crystal (rhombohedral crystal) as the main phase. The anisotropic magnet powder refers to a magnet powder in which each magnet particle constituting the magnet powder is a single crystal, or each magnet particle constituting the magnet powder is composed of multiple fine single crystal grains (magnetic domains), and the directions of the easy magnetization axes of each grain are aligned with a specific direction. For example, at least a part of the SmFeN powder can be an isotropic magnet powder containing TbCu7-type crystal (hexagonal crystal) as the main phase. The isotropic magnet powder refers to a magnet powder in which each magnet particle constituting the magnet powder is composed of multiple fine single crystal grains (magnetic domains), and the directions of the easy magnetization axes of each grain are disordered.

[0100] The method for manufacturing SmFeN powder is not limited. For example, the method for manufacturing SmFeN powder may include a step of forming an alloy powder containing Sm and Fe by mechanical alloying, and a step of heating the alloy powder in nitrogen to obtain SmFeN powder. SmFeN powder can be manufactured by rapid solidification method. In the rapid solidification method, the molten alloy is supplied to the surface of a rotating water-cooled roll. As a result, the molten alloy is rapidly cooled and solidified on the surface of the water-cooled roll. SmFeN powder is obtained by pulverizing the solidified alloy. Also, SmFe powder can be manufactured by the HDDR (Hydrogenation Disproportionation Desorption Recombination) method.

[0101] As the SmFeN powder, for example, non-pulverized powder (spherical magnet powder) obtained by the lamination method of Nichia Corporation can be used. By subjecting each magnet particle constituting the SmFeN powder to surface treatment, the surface of each magnet particle can be covered with a film of an inorganic substance. For example, the film of an inorganic substance may contain a phosphate or a silica-based compound.

[0102] The average particle diameter d of the SmFeN powder 50 is preferably 0.5 μm or more and 100 μm or less, more preferably 1 μm or more and 10 μm or less, and still more preferably 2 μm or more and 3 μm or less. The average particle diameter of the SmFeN powder can be measured by a laser diffraction particle size distribution measuring instrument.

[0103] <Wax>

[0104] For example, the wax may be at least one composition selected from the group consisting of synthetic waxes, saturated fatty acids, saturated fatty acid salts, and saturated fatty acid esters. For example, the wax may be at least one wax selected from the group consisting of polyethylene wax, amide wax, and montan wax. As commercially available products of polyethylene wax, at least one selected from the group consisting of Licolub H12, Licowax PE520, and Licowax PED191 (the above are product names manufactured by Clariant Chemicals Co., Ltd.) can be used. As commercially available products of amide wax, at least any one of Licolub FA1 (product name manufactured by Clariant Chemicals Co., Ltd.) and DISPARLON 6650 (product name manufactured by Kusumoto Chemicals, Ltd.) can be used. As commercially available products of montan wax, at least one selected from the group consisting of Licowax E, Licowax OP, Licolub E, and Licolub WE40 (the above are product names manufactured by Clariant Chemicals Co., Ltd.) can be used. Licowax E, Licowax OP, Licolub E, and Licolub WE40 are all montan acid esters.

[0105] The wax can be appropriately selected according to the orientation of the magnet powder in the molding process, the mold release property of the molded body, the molding temperature and pressure, and the matters required in the design of the composite such as the melting point, dropping point, and melt viscosity of the wax. From the viewpoint of easily improving the orientation of the magnet powder in the molding process, the above wax is preferably montan wax (montan acid ester), and particularly preferably Licowax E. The dropping point of Licowax E (montan acid ester) is 82 °C, and the melt viscosity of Licowax E (montan acid ester) at 100 °C is 30 mPa·s.

[0106] The composite may contain one of the above waxes. The composite may also contain a plurality of the above waxes.

[0107] <Resin composition>

[0108] In the present embodiment, the "resin composition" refers to the remaining part (non-volatile component) of the composite except for the magnet powder and the wax. The resin composition contains at least a thermosetting resin. The resin composition may further contain at least one component selected from the group consisting of a curing agent, a curing accelerator, a coupling agent, a flame retardant, and a flow aid. The composite itself may contain an organic solvent.

[0109] The resin composition functions as a binding material (adhesive) for binding multiple magnet particles that constitute the bonded magnet to each other. That is, the resin composition imparts mechanical strength to the anisotropic bonded magnet manufactured from the composite. For example, in the above molding process, the resin composition is filled between multiple magnet particles and binds the magnet particles to each other. Through the thermal curing of the resin composition, the cured product of the resin composition binds the magnet particles to each other more firmly.

[0110] For example, the thermosetting resin contained in the resin composition may be at least one resin selected from the group consisting of epoxy resins, phenolic resins (including phenol novolac resins), maleimide compounds, polyimides, polyamides, and polyamide-imides. When the composite contains both an epoxy resin and a phenolic resin, the phenolic resin can function as a curing agent for the epoxy resin. The thermosetting resin in the composite may be at least any one of an uncured resin and a semi-cured resin.

[0111] The mass of the magnet powder in the composite is represented as Mm (unit: g), and the total mass of the resin composition in the composite is represented as Mr (unit: g). The occupancy rate is defined as M / (Mm + Mr)×100. The duty factor may be 90.0 or more and 99.9 or less, preferably 95.0 or more and 99.5 or less, and more preferably 96.0 or more and 98.0 or less. When the duty factor is 90.0 or more, the anisotropic bonded magnet is likely to have a sufficiently high residual magnetic flux density. When the duty factor is 99.9 or less, the anisotropic bonded magnet is likely to have a sufficiently high mechanical strength.

[0112] <Epoxy Resin>

[0113] Any epoxy resin can be used as long as it has two or more epoxy groups in one molecule. From the viewpoint of improving the heat resistance (mechanical strength at high temperatures) of the anisotropic bonded magnet, heat-resistant epoxy resins such as naphthalene-type epoxy resins are preferred.

[0114] For example, the epoxy resin can be selected from biphenyl epoxy resin, stilbene epoxy resin, diphenylmethane epoxy resin, sulfur-containing epoxy resin, novolac epoxy resin, dicyclopentadiene epoxy resin, salicylaldehyde epoxy resin, naphthol-phenol copolymerized epoxy resin, aralkyl phenol resin epoxide, bisphenol epoxy resin, alcohol glycidyl ether epoxy resin, p-xylene modified phenolic resin and / or m-xylene modified phenolic resin glycidyl ether epoxy resin, terpene modified phenolic resin glycidyl ether epoxy resin. At least one member selected from the group consisting of epoxy resins, cyclopentadiene-based epoxy resins, glycidyl ether-based epoxy resins of polycyclic aromatic ring-modified phenolic resins, glycidyl ether-based epoxy resins of naphthalene-containing phenolic resins, glycidyl ester-based epoxy resins, glycidyl or methylglycidyl-based epoxy resins, alicyclic epoxy resins, halogenated phenol novolac-based epoxy resins, o-cresol novolac-based epoxy resins, hydroquinone-based epoxy resins, trimethylolpropane-based epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefinic bonds with a peracid such as peracetic acid. Examples of epoxy resins with high crystallinity include hydroquinone-based epoxy resins, bisphenol-based epoxy resins, thioether-based epoxy resins, and biphenyl-based epoxy resins.

[0115] At least a portion of the epoxy resin may be a naphthalene-type epoxy resin having a naphthalene structure. Naphthalene-type epoxy resins are solid at room temperature. When the composite contains a naphthalene-type epoxy resin, the anisotropic bonded magnet tends to have high mechanical strength at room temperature and high temperatures. For example, the naphthalene-type epoxy resin may be at least one epoxy resin selected from the group consisting of naphthalene diepoxides, naphthylene ether-type epoxy resins, naphthalene novolac-type epoxy resins, methylene-bonded dimers of naphthalene diepoxides, and methylene-bonded products of naphthalene monoepoxides and naphthalene diepoxides.

[0116] The naphthalene-type epoxy resin is preferably at least one of a trifunctional epoxy resin and a tetrafunctional epoxy resin. The naphthalene-type epoxy resin is more preferably a tetrafunctional epoxy resin. When the naphthalene-type epoxy resin contained in the composite is at least one of a trifunctional epoxy resin and a tetrafunctional epoxy resin, the naphthalene-type epoxy resins are three-dimensionally cross-linked with each other during the above-mentioned thermal curing process to form a strong cross-linked network. As a result, the movement of the naphthalene-type epoxy resin in the anisotropic bonded magnet is easily suppressed at high temperatures. That is, the glass transition temperature of each of the trifunctional epoxy resin and the tetrafunctional epoxy resin is higher than the glass transition temperature of the bifunctional epoxy resin. Therefore, when the naphthalene-type epoxy resin contained in the composite is at least one of a trifunctional epoxy resin and a tetrafunctional epoxy resin, the anisotropic bonded magnet is likely to have high mechanical strength at high temperatures.

[0117] For example, as a trifunctional naphthalene-type epoxy resin or a tetrafunctional naphthalene-type epoxy resin, commercially available products such as HP-4700, HP-4710, HP-4770, EXA-5740, or EXA-7311-G4 manufactured by DIC Corporation can be used. The naphthalene-type epoxy resin contained in the composite can be a difunctional epoxy resin. As the difunctional naphthalene-type epoxy resin, commercially available products such as HP-4032 or HP-4032D can be used. The naphthalene-type epoxy resin contained in the composite powder can be a β-naphthol-type epoxy resin.

[0118] The composite can contain one of the above epoxy resins. The composite can also contain a plurality of the above epoxy resins.

[0119] <Curing Agent / Phenolic Resin>

[0120] Curing agents are classified into curing agents that cure epoxy resins in the range from low temperature to room temperature and heat-curing type curing agents that cure epoxy resins upon heating. Curing agents that cure epoxy resins in the range from low temperature to room temperature are, for example, aliphatic polyamines, polyaminoamides, and polythiols. Heat-curing type curing agents are, for example, aromatic polyamines, acid anhydrides, phenol novolac resins, and dicyandiamide (DICY).

[0121] When using a curing agent that cures epoxy resins in the range from low temperature to room temperature, the glass transition point of the cured product of the epoxy resin tends to be low, and the cured product of the epoxy resin tends to be soft. As a result, the anisotropic bonded magnet manufactured from the composite also easily becomes soft. Therefore, from the viewpoint of improving the heat resistance of the anisotropic bonded magnet, the curing agent is preferably a heat-curing type curing agent, more preferably a phenolic resin, and further preferably a phenol novolac resin. In particular, by using a phenol novolac resin as the curing agent, it is easy to obtain a cured product of an epoxy resin having a high glass transition point. As a result, the heat resistance of the anisotropic bonded magnet is easily improved.

[0122] For example, the phenolic resin can be at least one selected from the group consisting of aralkyl-type phenolic resins, dicyclopentadiene-type phenolic resins, salicylaldehyde-type phenolic resins, novolac-type phenolic resins, copolymer-type phenolic resins of benzaldehyde-type phenols and aralkyl-type phenols, p-xylene and / or m-xylene modified phenolic resins, melamine modified phenolic resins, terpene modified phenolic resins, dicyclopentadiene-type naphthol resins, cyclopentadiene modified phenolic resins, polycyclic aromatic ring modified phenolic resins, biphenyl-type phenolic resins, and triphenylmethane-type phenolic resins. The phenolic resin can be a copolymer composed of two or more of the above phenolic resins.

[0123] A phenol novolak resin can be, for example, a resin obtained by condensing or co - condensing phenols and / or naphthols and aldehydes under an acidic catalyst. The phenols constituting the phenol novolak resin can be, for example, at least one selected from the group consisting of phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. The naphthols constituting the phenol novolak resin can be, for example, at least one selected from the group consisting of α - naphthol, β - naphthol, and dihydroxynaphthalene. The aldehydes constituting the phenol novolak resin can be, for example, at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde.

[0124] The curing agent can also be, for example, a compound having two phenolic hydroxyl groups in one molecule. The compound having two phenolic hydroxyl groups in one molecule can be, for example, at least one selected from the group consisting of resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted bisphenols.

[0125] As commercially available phenolic resins, for example, Tamanol 758 and 759 manufactured by Arakawa Chemical Industries, Ltd., HP - 850N manufactured by Showa Denko Materials co., Ltd., etc. can be cited.

[0126] The composite can contain one of the above - mentioned phenolic resins. The composite can contain a plurality of the above - mentioned phenolic resins.

[0127] The ratio of the hydroxyl equivalent of the phenolic resin to the epoxy equivalent of the epoxy resin can be 0.5 or more and 1.5 or less, 0.9 or more and 1.4 or less, 1.0 or more and 1.4 or less, or 1.0 or more and 1.2 or less. That is, with respect to 1 equivalent of epoxy groups in the epoxy resin, the ratio of the active groups (phenolic OH groups) in the phenolic resin that react with the epoxy groups in the epoxy resin can be preferably 0.5 equivalent or more and 1.5 equivalents or less, more preferably 0.9 equivalent or more and 1.4 equivalents or less, further preferably 1.0 equivalent or more and 1.4 equivalents or less, and particularly preferably 1.0 equivalent or more and 1.2 equivalents or less. When the ratio of the active groups in the phenolic resin is less than 0.5 equivalent, the amount of OH per unit weight of the cured epoxy resin decreases, and the curing rate of the resin composition (epoxy resin) decreases. Also, when the ratio of the active groups in the phenolic resin is less than 0.5 equivalent, the glass transition temperature of the obtained cured product tends to decrease, and it is difficult to obtain a sufficient elastic modulus of the cured product. On the other hand, when the ratio of the active groups in the phenolic resin is 1.5 equivalents or less, the anisotropic bonded magnet is likely to have high mechanical strength.

[0128] <Maleimide compounds: Bismaleimide, and aminophenol adducts>

[0129] The maleimide compound is at least one compound among bismaleimide and an aminophenol adduct of bismaleimide. The imide ring constituting bismaleimide is rigid. The phenyl ring constituting the aminophenol adduct of bismaleimide is also rigid. Due to these molecular structures, the maleimide compound has excellent heat resistance and is not easily thermally expanded compared with conventional thermosetting resins (for example, epoxy resins). In particular, the crosslinking density of the aminophenol adduct is relatively high. Based on the above characteristics of the maleimide compound, the maleimide compound (in particular, the aminophenol adduct) has excellent heat resistance and is not easily thermally expanded compared with conventional thermosetting resins (for example, epoxy resins). In other words, the maleimide compound (in particular, the aminophenol adduct) is difficult to soften and deform at high temperatures. Therefore, the anisotropic bonded magnet manufactured from the composite containing the maleimide compound (in particular, the aminophenol adduct) can have high mechanical strength at high temperatures (for example, 150 °C).

[0130] Bismaleimide (the following bismaleimide class (a)) is a compound (for example, monomer or polymer) containing a structural unit having two or more maleimide groups. The aminophenol adduct of bismaleimide is an addition reaction product (for example, addition polymer) of bismaleimide class (a) and aminophenol class (b). That is, the aminophenol adduct of bismaleimide can be obtained by the addition reaction (for example, addition polymerization reaction) of bismaleimide class (a) and aminophenol class (b). For example, one molecule of the aminophenol adduct can be synthesized by the reaction of one molecule of bismaleimide class (a) with one or more molecules of aminophenol class (b). An epoxy compound (c) (epoxy resin) can be added to the maleimide compound (particularly the aminophenol adduct). By the thermal curing of the maleimide compound (particularly the aminophenol adduct) added with the epoxy compound (c), the maleimide compound (particularly the aminophenol adduct) is modified by the epoxy compound (c) to form a complex network structure composed of the maleimide compound (particularly the aminophenol adduct) and the epoxy compound (c). As a result, the glass transition temperature of the cured product formed by the maleimide compound (particularly the aminophenol adduct) and the epoxy compound (c) is liable to increase, and the mechanical strength of the anisotropic bonded magnet at high temperatures is liable to become high.

[0131] Bismaleimide class (a) is represented by the following chemical formula A.

[0132]

[0133] R in the above chemical formula A 1 is an n-valent organic group. X in the above chemical formula A 1 and X 2A monovalent atom or monovalent organic group selected from hydrogen or a halogen. X 1 and X 2 may be the same, and X 1 and X 2 may be different from each other. n in the above chemical formula A is an integer of 2 or more.

[0134] For example, the bismaleimide (a) may be at least one compound selected from the group consisting of ethylenebismaleimide, hexamethylenebismaleimide, m-phenylenebismaleimide, p-phenylenebismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane (alias; bisphenol A bis(4-maleimidophenyl ether)), 4,4'-bismaleimidodiphenylmethane (alias; 4,4'-diphenylmethane bismaleimide), 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 4,4'-dicyclohexylmethane bismaleimide, m-xylylene bismaleimide, p-xylylene bismaleimide, and 4,4'-phenylenebismaleimide. The composite powder may further contain monomaleimides as needed. The monomaleimides may be, for example, N-3-chlorophenylmaleimide or N-4-nitrophenylmaleimide.

[0135] The above aminophenols (b) constituting the aminophenol adduct of bismaleimide are represented by the following chemical formula B.

[0136]

[0137] R in Chemical Formula B 2 represents a monovalent atom or monovalent organic group selected from hydrogen or a halogen. m in Chemical Formula B is an integer of 1 or more and 5 or less.

[0138] The aminophenol adduct represented by the following chemical formula C can be synthesized from the bismaleimides (a) represented by the above chemical formula A and the aminophenols (b) represented by the above chemical formula B.

[0139] α in the following chemical formula C is an integer of 1 or more and n or less.

[0140] R in the following chemical formula C 1 is an n-valent organic group. X in the following chemical formula C 1 and X 2 are each a monovalent atom or monovalent organic group selected from hydrogen or a halogen. X 1 and X 2 may be the same, and X 1 and X 2 may be different from each other. n of the following chemical formula C is an integer of 2 or more.

[0141] In the following chemical formula C, R 2 is a monovalent atom or a monovalent organic group selected from hydrogen or a halogen. In the following chemical formula C, m is an integer of 1 or more and 5 or less.

[0142]

[0143] For example, the aminophenols (b) may be at least one compound selected from the group consisting of o-aminophenol, m-aminophenol, p-aminophenol, o-aminocresol, m-aminocresol, p-aminocresol, aminoxylenol, aminochlorophenol, aminobromophenol, aminocatechol, aminoresorcinol, aminobis(hydroxyphenol) propane, and aminooxybenzoic acid.

[0144] The composite powder may further contain a compound other than the aminophenols (b) as a copolymer polymerized with the bismaleimides (a). For example, the composite powder may further contain at least one compound selected from the group consisting of aromatic amines, vinyl compounds, allyl compounds, allylphenols, and isocyanates other than the aminophenols (b) as a comonomer polymerized with the bismaleimides (a).

[0145] The above epoxide (c) added to the maleimide compound may have two or more epoxy groups in the molecule. For example, the epoxide (c) may be at least one compound selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, glycidyl ester resin of polycarboxylic acid, polyglycidyl ether of polyol, polyurethane-modified epoxy resin, fatty acid type polyepoxide obtained by epoxidizing an unsaturated compound, alicyclic polyepoxide obtained by epoxidizing an unsaturated compound, epoxy resin having a heterocycle, epoxy resin having an isocyclic ring, and epoxy resin obtained by glycidylating ammonia.

[0146] With respect to 100 parts by mass of the bismaleimides (a), the mass ratio of the aminophenols (b) may be 0 to 40 parts by mass, 5 to 40 parts by mass, preferably 10 to 30 parts by mass. When the mass ratio of the aminophenols (b) is 5 parts by mass or more, the compatibility of the addition reaction product with the above epoxide (c) is sufficient. When the mass ratio of the aminophenols (b) is 40 parts by mass or less, the number of amino groups in the aminophenol adduct is moderately suppressed, and the aminophenol adduct easily has excellent heat resistance. The reaction temperature of the bismaleimides (a) and the aminophenols (b) may be, for example, 50 to 200°C, preferably 80 to 180°C. The reaction time of the bismaleimides (a) and the aminophenols (b) can be appropriately adjusted within the range of several minutes to several tens of minutes.

[0147] The proportion of the maleimide compound in all the thermosetting resins contained in the composite powder can be, for example, 30 to 100% by mass or 30 to 80% by mass.

[0148] As the resin composition containing the aminophenol adduct of bismaleimide, at least one commercially available product selected from KIR-3, KIR-30, KIR-50, and KIR-100 (the above are product names manufactured by KYOCERA Corporation) can be used. KIR-3 is an example of an aminophenol adduct that does not contain the epoxy compound (c) (epoxy resin). KIR-30 is an example of an aminophenol adduct to which the epoxy compound (c) (epoxy resin) is added.

[0149] For example, KIR-3 and KIR-30 contain 4,4'-diphenylmethane bismaleimide represented by the following Chemical Formula 1 as the bismaleimide.

[0150]

[0151] For example, KIR-3 and KIR-30 contain m-aminophenol represented by the following Chemical Formula 2.

[0152]

[0153] For example, KIR-30 contains bisphenol A type epoxy resin represented by the following Chemical Formula 3 as the epoxy compound (epoxy resin). n in the following Chemical Formula 3 is an integer of zero or more.

[0154]

[0155] For example, KIR-3 and KIR-30 contain the aminophenol 1 adduct represented by the following Chemical Formula 4. The aminophenol 1 adduct is synthesized by the addition reaction of one molecule of 4,4'-diphenylmethane bismaleimide and one molecule of m-aminophenol.

[0156]

[0157] For example, KIR-3 and KIR-30 contain the aminophenol 2 adduct represented by the following Chemical Formula 5. The aminophenol 2 adduct can be synthesized by the addition reaction of one molecule of 4,4'-diphenylmethane bismaleimide and two molecules of m-aminophenol. The aminophenol 2 adduct can be synthesized by the addition reaction of one molecule of the above aminophenol 1 adduct and one molecule of m-aminophenol.

[0158]

[0159] <Polyimide>

[0160] For example, the polyimide may be a dehydration condensate of a tetracarboxylic dianhydride and 4,4'-bis(3-aminophenoxy)biphenyl. The polyimide may be at least one resin selected from AURUM PL450C, AURUM PL500A, AURUM PL6200, AURUM PD450L (products manufactured by Mitsui Chemicals, Inc.), SolverPI-5600 (a product manufactured by Solvar), and THERPLIM (a product manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0161] <Polyamide>

[0162] For example, the polyamide may be at least any one of particles of nylon 6 obtained from ε-caprolactam and particles of nylon 12 obtained from laurolactam. For example, the polyamide may be at least one resin selected from the group consisting of particles formed of nylon 6 (TR-1 and TR-2 manufactured by Toray Industries, Inc.); and particles formed of nylon 12 (SP-500 and SP-10 manufactured by Toray Industries, Inc.).

[0163] <Polyamideimide>

[0164] For example, the polyamideimide may be a polyamideimide having a siloxane structure. The polyamideimide may have two or more carboxyl groups at at least one of the two ends of the molecular chain of the polyamideimide. The polyamideimide may be the polyamideimide described in Japanese Unexamined Patent Application Publication No. 2019-48948.

[0165] <Other Resins>

[0166] The resin composition may contain the above-mentioned various thermosetting resins. In addition to the above thermosetting resins, the resin composition may also contain other resins. For example, as long as the mechanical strength of the anisotropic bonded magnet is not impaired, the resin composition may contain a thermoplastic resin in addition to the thermosetting resin. For example, the resin composition may also contain at least one other resin selected from the group consisting of polyphenylene sulfide resin, acrylic resin, methacrylic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and silicone resin.

[0167] <Curing Accelerator>

[0168] For example, the curing accelerator may contain imidazoles. For example, the imidazole-based curing accelerator may be at least one compound selected from 1-cyanoethyl-2-undecylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-phenylimidazole. As commercially available products of the imidazole-based curing accelerator, for example, 2MZ-H, C11Z, C17Z, 1,2DMZ, 2E4MZ, 2PZPW, 2P4MZ, 1B2MZ, 1B2PZ, 2MZ-CN, C11Z-CN, 2E4MZ-CN, 2PZ-CN, C11Z-CNS, 2P4MHZ, TPZ, and SFZ (the above are product names manufactured by Shikoku Chemicals Corporation) etc. can be cited. Among these, C17Z is preferred. By using the above-mentioned curing accelerator, an anisotropic bonded magnet excellent in heat resistance can be obtained.

[0169] The curing accelerator may contain a tetra-substituted phosphonium·tetra-substituted borate. The tetra-substituted phosphonium·tetra-substituted borate may be a compound represented by the following formula (I-0).

[0170]

[0171] In formula (I-0), R 51 ~R 58 are each independently an organic group having 1 to 18 carbon atoms. R 51 ~R 58 may all be the same, and R 51 ~R 58 may also be different from each other.

[0172] In the above general formula (I-0), R 51 ~R 58 may be at least one organic group selected from the group consisting of a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aliphatic hydrocarbon oxy group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted oxycarbonyl group, a substituted or unsubstituted carbonyloxy group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted aromatic hydrocarbon oxy group.

[0173] For example, the substituted or unsubstituted aliphatic hydrocarbon group may be an aliphatic hydrocarbon group such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, decyl, dodecyl, aryl, and vinyl, and an organic group obtained by substituting these with an alkyl group, an alkoxy group, an aryl group, a hydroxyl group, an amino group, and a halogen atom etc.

[0174] The substituted or unsubstituted aliphatic hydrocarbon group includes a substituted or unsubstituted alicyclic hydrocarbon group. For example, the substituted or unsubstituted alicyclic hydrocarbon group may be cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl, cyclohexenyl, etc., and organic groups obtained by substituting them with an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a hydroxyl group, an amino group, a halogen atom, etc.

[0175] For example, the substituted or unsubstituted aromatic hydrocarbon group may be

[0176] an aryl group such as phenyl and tolyl;

[0177] an alkyl-substituted aryl group such as dimethylphenyl, ethylphenyl, butylphenyl, and tert-butylphenyl;

[0178] an alkoxy-substituted aryl group such as methoxyphenyl, ethoxyphenyl, butoxyphenyl, and tert-butoxyphenyl; and

[0179] an organic group obtained by substituting these with an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group, a halogen atom, etc.

[0180] In the above general formula (I-0), R 51 ~R 54 may be a substituted or unsubstituted aliphatic hydrocarbon group, and R 55 ~R 58 may also be a substituted or unsubstituted aromatic hydrocarbon group.

[0181] For example, the tetra-substituted phosphonium·tetra-substituted borate may be at least one compound selected from the group consisting of tetrabutylphosphonium·tetraphenylborate, n-butyltriphenylphosphonium·tetraphenylborate, tetraphenylphosphonium·tetraphenylborate, trimethylphenylphosphonium·tetraphenylborate, diethylmethylphenylphosphonium·tetraphenylborate, diallylmethylphenylphosphonium·tetraphenylborate, (2-hydroxyethyl)triphenylphosphonium·tetraphenylborate, ethyltriphosphonium·tetraphenylborate, p-xylene bis(triphenylphosphonium·tetraphenylborate), tetraphenylphosphonium·tetraethylborate, tetraphenylphosphonium·triethylphenylborate, and tetraphenylphosphonium·tetrabutylborate. Among these, from the viewpoint of the storage stability of the complex, tetrabutylphosphonium tetraphenylborate is preferred.

[0182] As the compound represented by the above general formula (I-0), PX-4PB (manufactured by HOKKO CHEMICAL INDUSTRY CO., Ltd., product name) can be cited.

[0183] By using the above curing accelerator, an anisotropic bonded magnet excellent in heat resistance can be obtained. The complex may contain one of the above curing accelerators. The complex may contain a plurality of the above curing accelerators.

[0184] The compounding quantity of the curing accelerator is not particularly limited as long as it is an amount capable of obtaining a curing acceleration effect. Among them, from the viewpoints of the curability of the thermosetting resin and the orientation of the magnet powder in the magnetic field, the compounding quantity of the curing accelerator is preferably 0.1 part by mass or more and 30 parts by mass or less, more preferably 1 part by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the epoxy resin. When the compounding quantity of the curing accelerator is less than 0.1 part by mass, it is difficult to obtain a sufficient curing acceleration effect. When the compounding quantity of the curing accelerator exceeds 30 parts by mass, the storage stability of the composite is liable to decrease. The content of the curing accelerator is preferably 0.001 part by mass or more and 5 parts by mass or less relative to the total mass of the epoxy resin and the curing agent (such as a phenolic resin).

[0185] <Coupling agent>

[0186] The coupling agent may be a coupling agent that reacts with the glycidyl group possessed by a resin composition such as an epoxy resin (epoxy compound). The coupling agent improves the adhesion between the magnet particles and the resin composition and improves the mechanical strength of the anisotropic bonded magnet. The coupling agent that reacts with the glycidyl group may be, for example, a silane-based compound (silane coupling agent). For example, the silane coupling agent may be at least one selected from the group consisting of epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, acid anhydride-based silane (for example, silane having a succinic anhydride group), and vinyl silane.

[0187] The composite may contain one of the above coupling agents. The composite may contain a plurality of the above coupling agents.

[0188] <Flame retardant>

[0189] For the environmental safety, recyclability, molding processability, and low cost of the composite, the resin composition may contain a flame retardant. For example, the flame retardant may be at least one compound selected from the group consisting of bromine-based flame retardants, phosphorus-based flame retardants, hydrated metal compound-based flame retardants, silicone-based flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics. The composite may contain one of the above flame retardants or may include a plurality of the above flame retardants.

[0190] <Production of composite>

[0191] The composite is obtained by mixing the magnet powder, the resin composition, and the wax. The mass of each of the magnet powder, the components constituting the resin composition, and the wax is adjusted to be consistent with the composition of the above composite. The magnet powder, all the components constituting the resin composition, and the wax may be mixed together. After previously preparing a mixture of the magnet powder and the resin composition, the mixture and the wax may be mixed.

[0192] After coating the surface of each magnet particle constituting the magnet powder with a resin composition, the magnet powder and wax can be mixed to obtain a composite in the following manner.

[0193] A resin solution is prepared by uniformly stirring and mixing the resin composition in an organic solvent. The resin solution may contain, in addition to the thermosetting resin, a curing agent, a curing accelerator, a coupling agent, a flame retardant, a flow aid, a reactive diluent, etc. The organic solvent is not particularly limited as long as it is a liquid that dissolves the resin composition. For example, the organic solvent may be at least one solvent selected from the group consisting of acetone, N-methylpyrrolidone (N-methyl-2-pyrrolidone), γ-butyrolactone, dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone, methyl isobutyl ketone, toluene, and xylene.

[0194] After stirring and mixing the above resin solution and magnet powder, the organic solvent is removed from the resin solution, whereby a mixed powder formed of the magnet powder and the resin composition can be obtained. As the organic solvent is removed from the resin solution, the resin composition adheres to the surface of each magnet particle constituting the magnet powder. The resin composition may adhere to the entire surface of each magnet particle. The resin composition may adhere only to a part of the surface of each magnet particle. The method for removing the organic solvent from the resin solution is not particularly limited. For example, by drying the mixture of the resin solution and the magnet powder, the organic solvent can be removed from the resin solution. For example, the method for drying the resin solution may be vacuum drying.

[0195] A composite can be obtained by further mixing the above mixed powder formed of the magnet powder and the resin composition and wax.

[0196] <Fabrication of small pieces>

[0197] Small pieces formed of the composite can be fabricated by compression molding the composite filled into a mold. The size and shape of the small pieces are not particularly limited. For example, the tablet may be cylindrical. For example, the diameter of the cylinder may be 5 mm or more, and the height of the cylinder may be 5 mm or more. From the viewpoint of easily maintaining the shape of the small pieces, the molding pressure for fabricating the small pieces is preferably 100 MPa or more. When the molding pressure for fabricating the small pieces is too high, it is difficult for the magnet powder to rotate and be oriented in the above molding process. For this reason, the molding pressure for fabricating the small pieces is preferably 600 MPa or less.

[0198] The present invention is not necessarily limited to the above-described embodiments. Various modifications of the present invention can be made without departing from the gist of the present invention, and these modification examples are also included in the present invention.

[0199] Examples

[0200] The present invention will be described in detail by the following examples and comparative examples. The present invention is not limited to the following examples.

[0201] (Example 1)

[0202] In a plastic bottle, magnet powder, a thermosetting resin, a curing accelerator, and wax were mixed for 1 hour to produce the composite (powder) of Example 1. The capacity of the plastic bottle was 500 ml.

[0203] As the magnet powder, SmFeN powder containing a main phase formed by Sm2Fe 17 N3 was used. The magnet powder was manufactured by Sumitomo Metal Mining Co., Ltd.

[0204] As the thermosetting resin, an epoxy resin and a phenol novolak resin were used.

[0205] As the epoxy resin, YX-4000H manufactured by Mitsubishi Chemical Corporation was used. YX-4000H is a biphenyl type epoxy resin.

[0206] As the phenol novolak resin, HP-850N manufactured by Showa Denko Materials co., Ltd. was used.

[0207] As the curing accelerator, C17Z manufactured by SHIKOKU CHEMICALS CORPORATION was used. C17Z is an imidazole-based curing accelerator.

[0208] As the wax, Licowax E manufactured by Clariant Chemicals Co., Ltd. was used. Licowax E is a montanate. The dropping point of Licowax E was 82°C.

[0209] The mass of the magnet powder in the composite is shown in Table 1 below.

[0210] The mass of YX-4000H in the composite is shown in Table 1 below.

[0211] The mass of HP-850N in the composite is shown in Table 1 below.

[0212] The mass of C17Z in the composite is shown in Table 1 below.

[0213] The mass of Licowax E in the composite is shown in Table 1 below.

[0214] The unit of the mass recorded in Table 1 below is grams (g).

[0215] (M2 / M1)×100 is shown in Table 1 below. The definition of (M2 / M1)×100 is as described above.

[0216] By the following method, a magnetic formed body and an anisotropic bonded magnet were produced from the composite of Example 1. As the molding device (hydraulic stamping device), a TM-MPH10525-10A2TM type manufactured by TAMAGAWA Ltd. was used.

[0217] In the supply process, about 2 g of the composite was supplied into the mold of the molding device. The shape of the mold (cavity) was a cube, and the capacity of the mold (cavity) was 7 mm × 7 mm × 7 mm.

[0218] In the molding process, the mold was heated for 3 to 5 minutes until the temperature of the mold reached the molding temperature Tm. The molding temperature Tm was 100 °C. That is, the molding temperature Tm was higher than the dropping point of the wax (82 °C) and lower than the thermal curing temperature of the thermosetting resin in the composite.

[0219] As the molding process, the following first pressing process and the second pressing process immediately following the first pressing process were carried out. In the first pressing process, while applying a static magnetic field to the composite in the mold heated to the molding temperature Tm, the composite in the mold was compressed for 1 minute at 10 MPa (first pressure P1). The intensity of the static magnetic field was maintained at 1.0 T. In the second pressing process, the composite (formed body) in the mold heated to the molding temperature Tm was compressed at 1000 MPa (second pressure P2) for 5 minutes.

[0220] Through the above molding process, a formed body was formed from the composite. In the second pressing process, the wax was removed from the formed body. In the second pressing process, the wax removed from the formed body was discharged out of the mold (cavity) through the gap formed in the mold.

[0221] In the cooling process immediately following the molding process, the mold containing the formed body was cooled from 100 °C (molding temperature Tm) to 50 °C (a temperature lower than the dropping point of the wax). The mold was cooled in the atmosphere for about 10 minutes. After the cooling process, the formed body was taken out of the mold.

[0222] In the demagnetization process after the cooling process, the formed body was demagnetized by applying a reverse magnetic field to the formed body. The direction of the reverse magnetic field was opposite to the direction of the static magnetic field used in the molding process.

[0223] In the thermosetting process after the demagnetization process, a magnetic formed body was obtained by heating the formed body at 180 °C (a temperature above the thermal curing temperature of the thermosetting resin) for 20 minutes.

[0224] In the magnetization process after the thermosetting process, an anisotropic bonded magnet was obtained by applying a magnetic field to the magnetic compact. The direction of the magnetic field used in the magnetization process was the same as the direction of the static magnetic field used in the molding process.

[0225] <Measurement of Residual Flux Density>

[0226] The residual flux density Br (unit: tesla) of the anisotropic bonded magnet was measured. In the measurement of Br, a vibrating sample type magnetometer (Vibrating Sample Magnetometer; VSM) of the high-sensitivity type constant-conductivity electromagnet type (electromagnet type) was used. The vibrating sample type magnetometer was manufactured by TAMAGAWA Ltd. The residual flux density Br of the anisotropic bonded magnet of Example 1 is shown in Table 1 below.

[0227] <Measurement of Crushing Strength>

[0228] A compressive pressure was applied to the end face of the anisotropic bonded magnet using a universal compression testing machine. That is, in the height direction of the anisotropic bonded magnet, a compressive pressure was applied to the anisotropic bonded magnet. The compressive pressure was increased, and the compressive pressure at which the anisotropic bonded magnet was destroyed was measured. The compressive pressure at which the anisotropic bonded magnet was destroyed is the crushing strength (unit: MPa). As the universal compression testing machine, AG-10TRB manufactured by SHIMADZU CORPORATION was used. The speed of the crosshead in the measurement of the crushing strength was 0.5 mm / minute. The measurement of the crushing strength was carried out at room temperature. The crushing strength of the anisotropic bonded magnet of Example 1 is shown in Table 1 below.

[0229] (Example 2)

[0230] In the production of the composite of Example 2, KIR-30 was used as the thermosetting resin. As described above, KIR-30 is a product manufactured by Kyocera Corporation. KIR-30 contains a mixture of an aminophenol adduct of bismaleimide and an epoxy resin (uncured resin).

[0231] The mass of KIR-30 in the composite of Example 2 is shown in Table 1 below.

[0232] The mass of Licowax E in the composite of Example 2 is shown in Table 1 below.

[0233] (M2 / M1)×100 of Example 2 is shown in Table 1 below.

[0234] Except for the above matters, the composite, magnetic compact, and anisotropic bonded magnet of Example 2 were produced in the same manner as in Example 1. The Br and crushing strength of the anisotropic bonded magnet of Example 2 were measured in the same manner as in Example 1. The measurement results of Example 2 are shown in Table 1 below.

[0235] (Example 3)

[0236] In the production of the composite of Example 3, KIR-30 was used as the thermosetting resin.

[0237] The mass of KIR-30 in the composite of Example 3 is shown in Table 1 below.

[0238] The mass of Licowax E in the composite of Example 3 is shown in Table 1 below.

[0239] (M2 / M1)×100 of Example 3 is shown in Table 1 below.

[0240] Except for the above matters, the composite, magnetic compact, and anisotropic bonded magnet of Example 3 were produced in the same manner as in Example 1. The Br and crushing strength of the anisotropic bonded magnet of Example 3 were measured in the same manner as in Example 1. The measurement results of Example 3 are shown in Table 1 below.

[0241] (Example 4)

[0242] In the production of the composite of Example 4, KIR-30 was used as the thermosetting resin.

[0243] The mass of KIR-30 in the composite of Example 4 is shown in Table 1 below.

[0244] The mass of Licowax E in the composite of Example 4 is shown in Table 1 below.

[0245] (M2 / M1)×100 of Example 4 is shown in Table 1 below.

[0246] Except for the above matters, the composite, magnetic compact, and anisotropic bonded magnet of Example 4 were produced in the same manner as in Example 1. The Br and crushing strength of the anisotropic bonded magnet of Example 4 were measured in the same manner as in Example 1. The measurement results of Example 4 are shown in Table 1 below.

[0247] (Example 5)

[0248] The mass of the magnet powder in the composite of Example 5 is shown in Table 1 below.

[0249] The mass of YX-4000H in the composite of Example 5 is shown in Table 1 below.

[0250] The mass of HP-850N in the composite of Example 5 is shown in Table 1 below.

[0251] The mass of Licowax E in the composite of Example 5 is shown in Table 1 below.

[0252] (M2 / M1)×100 of Example 5 is shown in Table 1 below.

[0253] Except for the above matters, the composite, magnetic formed body, and anisotropic bonded magnet of Example 5 were produced in the same manner as in Example 1. In the same manner as in Example 1, Br and crushing strength of the anisotropic bonded magnet of Example 5 were measured. The measurement results of Example 5 are shown in Table 1 below.

[0254] (Comparative Example 1)

[0255] The molding temperature Tm in the molding process of Comparative Example 1 was 60°C. That is, the molding temperature Tm of Comparative Example 1 was lower than the dropping point of the wax (82°C).

[0256] Except for the above matters, the composite, magnetic formed body, and anisotropic bonded magnet of Comparative Example 1 were produced in the same manner as in Example 1. In the same manner as in Example 1, Br and crushing strength of the anisotropic bonded magnet of Comparative Example 1 were measured. The measurement results of Comparative Example 1 are shown in Table 1 below.

[0257] (Comparative Example 2)

[0258] The second pressure P2 in the second pressing process of Comparative Example 2 was 500 MPa. In the second pressing process of Comparative Example 2, the wax did not discharge out of the mold through the gap formed in the mold. That is, in the molding process of Comparative Example 2, the wax was not substantially removed from the formed body.

[0259] Except for the above matters, the composite, magnetic formed body, and anisotropic bonded magnet of Comparative Example 2 were produced in the same manner as in Example 1. In the same manner as in Example 1, Br and crushing strength of the anisotropic bonded magnet of Comparative Example 2 were measured. The measurement results of Comparative Example 2 are shown in Table 1 below.

[0260] (Comparative Example 3)

[0261] The second pressure P2 in the second pressing process of Comparative Example 3 was 500 MPa. In the second pressing process of Comparative Example 3, the wax did not discharge out of the mold through the gap formed in the mold. That is, in the molding process of Comparative Example 3, the wax was not substantially removed from the formed body.

[0262] Except for the above matters, a composite, a magnetic molded body, and an anisotropic bonded magnet of Comparative Example 3 were produced in the same manner as in Example 2. The Br and crush strength of the anisotropic bonded magnet of Comparative Example 3 were measured in the same manner as in Example 1. The measurement results of Comparative Example 3 are shown in Table 1 below.

[0263] (Comparative Example 4)

[0264] The demagnetization process of Comparative Example 4 was not carried out. Except for the demagnetization process, the production of the magnetic molded body and the anisotropic bonded magnet of Comparative Example 4 was attempted in the same manner as in Example 1. However, in the thermosetting process of Comparative Example 4, the surface of the molded body fluffed. As a result, the shape of the molded body and the orientation of the magnet powder in the molded body were impaired, and the magnetic molded body and the anisotropic bonded magnet of Comparative Example 4 could not be produced.

[0265] [Table 1]

[0266] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Magnet powder [g] 980 980 980 980 960 980 980 980 980 YX-4000H [g] 12.8 0 0 0 25.6 12.8 12.8 0 12.8 HP-850N [g] 7.2 0 0 0 14.4 7.2 7.2 0 7.2 KIR-30 [g] 0 20 20 20 0 0 0 20 0 Licowax E [g] 25 30 20 40 30 25 25 30 25 CZ17 [g] 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 (M2 / M1)×100 [-] 2.5 3.0 2.0 4.0 3.0 2.5 2.5 3.0 2.5 Br [T] 1.03 1.02 1.02 1.02 0.81 0.44 0.61 0.81 - Crushing strength [MPa] 58 37 38 37 54 52 45 29 -

[0267] Industrial Applicability

[0268] For example, according to one aspect of the present invention, an anisotropic bonded magnet excellent in residual magnetic flux density and mechanical strength can be provided.

[0269] Symbol Explanation

[0270] 2 - Composite, 2A - Molded body, 2B - Anisotropic bonded magnet, 3 - Magnet particles (magnet powder), 4 - Wax, 5 - Thermosetting resin (resin composition), 6 - Gap, 10 - Manufacturing apparatus (molding apparatus), c1 - First coil, c2 - Second coil, d1 - Die, H - Magnetic field, m - Magnetization direction of magnet particles, M - Magnetization direction of anisotropic bonded magnet, p1 - First punch, p2 - Second punch, P1 - First pressure, P2 - Second pressure.

Claims

1. A method for manufacturing a magnetic formed body, comprising: a supply step of supplying a composite containing magnet powder, a thermosetting resin, and wax into a mold; a molding step of compressing the composite in the mold while applying a magnetic field to the composite in the mold heated to a molding temperature Tm, thereby forming a formed body from the composite and removing the wax from the formed body; a demagnetization step of demagnetizing the formed body after the molding step; and a thermosetting step of heating the formed body to a temperature equal to or higher than the thermosetting temperature of the thermosetting resin after the demagnetization step, thereby obtaining a magnetic formed body, wherein the magnet powder contains an Sm-Fe-N-based permanent magnet, and the molding temperature Tm is equal to or higher than the dropping point of the wax and lower than the thermosetting temperature of the thermosetting resin.

2. The method for manufacturing a magnetic formed body according to claim 1, wherein the molding step includes a first pressing step and a second pressing step immediately following the first pressing step, in the first pressing step, the pressure applied to the composite in the mold heated to the molding temperature Tm is maintained at a first pressure P1, in the second pressing step, the pressure applied to the composite in the mold heated to the molding temperature Tm is maintained at a second pressure P2, the second pressure P2 is higher than the first pressure P1, and in the second pressing step, the wax is removed from the formed body.

3. The method for manufacturing a magnetic formed body according to claim 1, wherein in the molding step, the wax is removed from the formed body by continuously increasing the pressure applied to the composite in the mold heated to the molding temperature Tm to the second pressure P2.

4. The method for manufacturing a magnetic formed body according to any one of claims 1 to 3, further comprising: a cooling step of cooling the mold containing the formed body from the molding temperature Tm to a temperature lower than the dropping point, wherein the cooling step is performed after the molding step, and the demagnetization step is performed after the cooling step.

5. The method for manufacturing a magnetic formed body according to any one of claims 1 to 3, wherein a gap is formed in the mold, the viscosity of the wax at the molding temperature Tm is lower than the viscosity of the thermosetting resin at the molding temperature Tm, and in the molding step, the wax removed from the formed body is discharged out of the mold through the gap.

6. The method for manufacturing a magnetic formed body according to any one of claims 1 to 3, wherein the sum of the mass of the magnet powder and the mass of the thermosetting resin is represented as M1, the mass of the wax in the composite is represented as M2, (M2 / M1)×100 is 2 or more and 10 or less.

7. The method for manufacturing a magnetic formed body according to any one of claims 1 to 3, wherein the thermosetting resin contains at least one resin selected from the group consisting of epoxy resins, maleimide compounds, polyimides, polyamides, and polyamide-imides.

8. The manufacturing method of the magnetic formed body according to any one of claims 1 to 3, wherein, the wax contains montanic acid ester.

9. A manufacturing method of an anisotropic bonded magnet, which includes the manufacturing method of the magnetic formed body according to any one of claims 1 to 3, the manufacturing method of the anisotropic bonded magnet further includes a magnetization step of obtaining an anisotropic bonded magnet by magnetizing the magnetic formed body.

10. A manufacturing method of an anisotropic bonded magnet, which includes the manufacturing method of the magnetic formed body according to claim 4, the manufacturing method of the anisotropic bonded magnet further includes a magnetization step of obtaining an anisotropic bonded magnet by magnetizing the magnetic formed body.

11. A manufacturing method of an anisotropic bonded magnet, which includes the manufacturing method of the magnetic formed body according to claim 5, the manufacturing method of the anisotropic bonded magnet further includes a magnetization step of obtaining an anisotropic bonded magnet by magnetizing the magnetic formed body.

12. A manufacturing method of an anisotropic bonded magnet, which includes the manufacturing method of the magnetic formed body according to claim 6, the manufacturing method of the anisotropic bonded magnet further includes a magnetization step of obtaining an anisotropic bonded magnet by magnetizing the magnetic formed body.

13. A manufacturing method of an anisotropic bonded magnet, which includes the manufacturing method of the magnetic formed body according to claim 7, the manufacturing method of the anisotropic bonded magnet further includes a magnetization step of obtaining an anisotropic bonded magnet by magnetizing the magnetic formed body.

14. A manufacturing method of an anisotropic bonded magnet, which includes the manufacturing method of the magnetic formed body according to claim 8, the manufacturing method of the anisotropic bonded magnet further includes a magnetization step of obtaining an anisotropic bonded magnet by magnetizing the magnetic formed body.

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