core, iron core

Abstract

The present invention provides a core in which a plurality of plate-shaped soft magnetic materials are bonded with high adhesion between layers. The core (1) of the present invention includes a plurality of plate-shaped soft magnetic materials (2) laminated with a thermosetting resin layer (3) interposed therebetween, and rubber particles (4) are dispersed in the thermosetting resin layer (3). The content of the rubber particles (4) is preferably more than 0 phr and 8 phr or less when the content of the thermosetting resin is 100 phr. The thermosetting resin layer (3) is preferably an epoxy resin, an unsaturated polyester resin, or an acrylic resin.

Description

Technical Field

[0001] This invention relates to iron cores using adhesive laminates of soft magnetic materials. Background Technology

[0002] In recent years, due to environmental issues such as global warming, measures to reduce CO2 have become increasingly active. One such measure is the widespread adoption of electric vehicles (xEVs), such as electric cars or hybrid vehicles. Further efficiency improvements are required for the electric motors used in xEVs, and similarly, increased conversion efficiency is needed in transformers. Therefore, the development of low-loss soft magnetic materials for the stators, rotors, and cores used in electric motors and transformers is gaining momentum.

[0003] Currently, electromagnetic steel sheets are the mainstream soft magnetic material used in these iron cores, and the aforementioned iron cores are constructed by stacking these sheet-like electromagnetic steel sheets. As materials with high magnetic permeability and low iron loss characteristics for improving efficiency, the development of new soft magnetic materials such as amorphous alloys and nanocrystalline alloys is underway.

[0004] These new soft magnetic materials are manufactured by spreading a molten, homogenized slurry of any metal composition onto a metal plate or roller, followed by ultra-rapid casting. Therefore, these soft magnetic materials are produced as foil strips with a film thickness of tens of micrometers. In contrast, the film thickness of existing soft magnetic materials on electromagnet steel plates is hundreds of micrometers, making these new soft magnetic materials significantly thinner than existing ones.

[0005] Therefore, when using a new soft magnetic material to form the core of an electric motor or transformer, more layers are required compared to electromagnet steel sheets. Furthermore, the new soft magnetic material is thinner than electromagnet steel sheets, resulting in lower resistance to deflection or bending due to its own weight. Therefore, when using the new soft magnetic material, care must be taken to prevent deflection or bending during and after the layering process in core forming.

[0006] Therefore, when using new soft magnetic materials for iron cores, in order to make them resistant to bending or flexing, it is considered to bond the foil strips of soft magnetic materials together with any resin. Additionally, the iron cores of motors or transformers must be able to withstand the heat generated during operation.

[0007] Under these circumstances, the technology described in Patent Document 1 was proposed. Patent Document 1 describes that at least a portion of the magnetic material of the rotor or stator is composed of a laminate of amorphous metallic magnetic strips. Furthermore, Patent Document 1 describes that the aforementioned magnetic material is formed by alternately laminating layers of amorphous metallic magnetic strips and thermoplastic resin layers.

[0008] Furthermore, the technology described in Patent Document 2 is also proposed. Patent Document 2 describes filling a magnetic core formed by winding an amorphous magnetic foil strip with resin once every few turns of the magnetic foil strip. Additionally, Patent Document 2 describes filling the resin with spacers every few turns of the magnetic foil strip. Patent Document 2 describes using a thermoplastic resin or a thermosetting resin as the resin, and that it may contain silicon dioxide or aluminum oxide to improve thermal conductivity.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2004-048859

[0012] Patent Document 2: Japanese Patent Application Publication No. 2011-91932 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] However, the technology described in Patent Document 1 only uses thermoplastic resin, so the iron core manufactured using this technology may not have sufficient adhesion in the magnetic material.

[0015] Furthermore, in the technology described in Patent Document 2, resin is filled once every multiple turns of the magnetic foil strip, and resin is also filled once via spacers every multiple turns of the magnetic foil strip, so there is a possibility that the adhesion of the magnetic foil strip is not sufficient.

[0016] The objective of this invention is to provide an iron core in which multiple layers of plate-shaped soft magnetic materials are bonded together with high adhesiveness.

[0017] Technical solutions for solving the problem

[0018] The iron core of the present invention, which solves the above-mentioned problems, includes a plurality of plate-shaped soft magnetic materials and a thermosetting resin layer that bonds adjacent soft magnetic materials together, wherein rubber particles are dispersed in the thermosetting resin layer.

[0019] Invention Effects

[0020] According to the present invention, it is possible to provide an iron core in which multiple layers of plate-shaped soft magnetic materials are bonded together with high adhesiveness. Attached Figure Description

[0021] Figure 1 This is a schematic perspective view showing an example of the iron core of this embodiment.

[0022] Figure 2This is a partially enlarged cross-sectional view illustrating the stacked structure of the iron core in this embodiment.

[0023] Figure 3 This is a cross-sectional view showing the structure of the rubber particles that can be preferably used in this embodiment.

[0024] Figure 4 It is a schematic cross-sectional view showing the structure of the test piece when evaluating adhesion. Detailed Implementation

[0025] Hereinafter, an embodiment of the iron core of the present invention will be described in detail with appropriate reference to the accompanying drawings. Figure 1 This is a schematic perspective view showing an example of the iron core 1 in this embodiment. Figure 2 This is a partially enlarged cross-sectional view illustrating the laminated structure of the iron core 1 in this embodiment. Figure 3 These are cross-sectional views showing the structure of the rubber granules 4 that can be preferably used in this embodiment. Furthermore, the shapes and sizes of each element are exaggerated for ease of viewing and explanation.

[0026] (Core 1)

[0027] Figure 1 The iron core 1 shown is an example of the stator of an electric motor. Alternatively, the iron core 1 could also be the rotor. Figure 2 As shown, the core 1 of this embodiment includes, for example, a plurality of plate-shaped soft magnetic materials 2 stacked with a thermosetting resin layer 3 in between. Furthermore, rubber particles 4 are dispersed in the thermosetting resin layer 3.

[0028] (Soft magnetic material 2)

[0029] Soft magnetic material 2 can be manufactured into a foil-like strip by spreading a molten lava obtained by melting and homogenizing a metal of any composition on a metal plate or metal roller and then performing ultra-rapid casting. The soft magnetic material 2 manufactured in this way is an amorphous soft magnetic material (amorphous alloy) with low loss. Alternatively, the soft magnetic material 2 can be obtained, for example, by heat-treating the obtained foil-like soft magnetic material 2 to microcrystallize it and control the magnetic domain walls. The soft magnetic material 2 subjected to such heat treatment is called a nanocrystalline soft magnetic body (nanocrystalline alloy). Details regarding the metal composition of these soft magnetic materials 2 are not particularly limited as long as they are formed by the above method; alloys mainly composed of iron, silicon, and boron, or alloys to which phosphorus or copper are added, can be used.

[0030] The thickness of the soft magnetic material 2 is not particularly limited, but as mentioned above, it is generally a few μm to 50 μm because it is manufactured by spreading the molten slurry obtained by melting and homogenizing any metal composition on a metal plate or metal roller and then performing ultra-rapid casting.

[0031] (Thermosetting resin layer 3)

[0032] The thermosetting resin layer 3 is composed of a resin composition that is liquid at room temperature before curing. In this embodiment, the lower the viscosity of the resin composition, the better. Examples of such resin compositions include epoxy resin compositions, unsaturated polyester resin compositions, and acrylic resin compositions. If these resin compositions are used, the thermosetting resin layer 3 can be appropriately formed.

[0033] As a component of epoxy resin, a mixture of epoxy resin and any hardener can be used. The epoxy resin can be selected in any way that corresponds to its heat resistance and adhesion. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic resin, etc., can be used as the epoxy resin, but it is not limited to these.

[0034] As the aforementioned curing agent, any general curing agent used for epoxy resins can be used. Examples of such curing agents include anhydrides such as maleic anhydride, phthalic anhydride, and tetrahydrophthalic anhydride, as well as aliphatic amines or polyamines such as diethylenetriamine, triethylenetetramine, diaminodiphenylmethane, and sulfamic acid, and aromatic amines.

[0035] The catalyst can be arbitrarily selected / applied in accordance with the curing temperature of the epoxy resin composition. For example, compounds with an imidazole structure, such as 2-methylimidazole, can be used as such catalysts.

[0036] Regarding these curing agents and catalysts that can be used to cure epoxy resin compositions, as long as the epoxy resin is in a liquid state at room temperature and can be coated on the soft magnetic material 2, the types and proportions of the materials contained therein are not limited in any way.

[0037] Regarding these curing agents and catalysts that can be used to cure epoxy resin compositions, any curing agent and catalyst, including commercially available curing agents and catalysts, can be used, as long as their function can be achieved.

[0038] As a component of unsaturated polyester resin, a mixture of vinyl ester resin with any curing agent and any reaction initiator can be used.

[0039] Examples of hardeners used in this process include reactive diluents. Reactive diluents can include vinyl monomers such as styrene and vinyltoluene, acrylate monomers such as methyl methacrylate, or methacrylate monomers.

[0040] Thermal free radical initiators can be cited as examples of reaction initiators used in this process. Examples of thermal free radical initiators include azo compound derivatives such as 2,2'-azobisbutyronitrile, or organic peroxides such as benzoyl peroxide.

[0041] Regarding these curing agents and reaction initiators that can be used to cure unsaturated polyester resin compositions, as long as the unsaturated polyester resin compositions are liquid at room temperature and can be coated on soft magnetic material 2, the types and proportions of the materials contained therein are not limited in any way.

[0042] Regarding the curing agents and reaction initiators that can be used to cure unsaturated polyester resin compositions, similar to the epoxy resins described above, any curing agent and reaction initiator, including commercially available curing agents and reaction initiators, can be used as long as their functions can be achieved.

[0043] As a component of acrylic resin, any mixture of acrylate monomers and methacrylate monomers can be used. For example, a composition formed by mixing monomers such as ethyl acrylate, hydroxyethyl acrylate, or methyl methacrylate in any proportion can be used as a component of acrylic resin.

[0044] Acrylic resins are synthesized by addition polymerization (free radical polymerization) using free radicals as reaction initiators. Examples of reaction initiators include thermal free radical initiators. Examples of thermal free radical initiators include azo compound derivatives such as 2,2'-azobisbutyronitrile and organic peroxides such as benzoyl peroxide.

[0045] Regarding reaction initiators that can be used for curing compositions of acrylic resins, similar to the epoxy resins described above, any reaction initiator, including commercially available reaction initiators, can be used as long as it can achieve its function.

[0046] The thickness of the thermosetting resin layer 3 is not particularly limited, but in this embodiment, it is preferable to be thinner than the soft magnetic material 2 in the core 1. This allows for an increase in the number of layers of soft magnetic material 2 per unit volume, thus improving the performance of the core 1.

[0047] (Rubber granules 4)

[0048] As described above, regarding the thermosetting resin layer 3, rubber particles 4 are dispersed within the layer. Because the rubber particles 4 are dispersed within the thermosetting resin layer 3, the stress generated during shearing or peeling of the thermosetting resin layer 3 can be reduced, or the progression of resin degradation can be inhibited (i.e., cohesive failure can be suppressed). Therefore, the toughness of the thermosetting resin layer 3 itself is improved, which enhances the adhesion between adjacent soft magnetic materials 2.

[0049] The size (particle diameter) of the rubber particles 4 is preferably smaller than the thickness of the thermosetting resin layer 3. This results in smaller rubber particles 4, which are less likely to interfere with the adhesion between adjacent soft magnetic materials 2. Therefore, the thickness of the thermosetting resin layer 3 can be reduced while simultaneously improving adhesion.

[0050] The size of the rubber particles 4 can be, for example, 10 nm or more and 1 μm or less. Because the size of the rubber particles 4 is sufficiently small, it is less likely to hinder the adhesion between adjacent soft magnetic materials 2. Furthermore, because the size of the rubber particles 4 is sufficiently small, it is less likely to form unevenness on the surface of the thermosetting resin layer 3. Moreover, because the size of the rubber particles 4 is sufficiently small, the thickness of the thermosetting resin layer 3 can be reliably reduced. The size of the rubber particles 4 can be, for example, 50 nm or more, 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or more. The size of the rubber particles 4 can also be 900 nm or less, 800 nm or less, 700 nm or less, or 600 nm or less.

[0051] Regarding the rubber particles 4, rubber particles formed from any material can be used to correspond with the heat resistance and adhesion of the thermosetting resin layer 3. The rubber particles 4 are preferably formed from, for example, butadiene rubber, acrylic rubber, methacrylic rubber, silicone rubber, styrene rubber, or copolymers or mixtures of these rubbers, MBS (methacrylic-butadiene-styrene) rubber, or ABS (acrylic-butadiene-styrene) rubber. Furthermore, to further improve heat resistance, the rubber particles 4 can also be formed from fluororubber having fluorine atoms in the molecular structure constituting the rubber. Examples of such fluororubbers include vinylidene fluoride rubber, tetrafluoroethylene-perfluorovinyl ether rubber, and tetrafluoroethylene-propylene rubber, or combinations of these fluororubbers, or mixtures with one of the aforementioned rubber particles. When the rubber particles 4 are formed from these materials, compared to inorganic particles, the rubber particles 4 have a similar specific gravity to the thermosetting resin 4, and therefore can be dispersed relatively stably without settling before curing. Therefore, the adhesion between adjacent soft magnetic materials 2 is further improved.

[0052] In addition, such as Figure 3As shown, the rubber particle 4 is preferably a multilayer rubber particle 4a having a rubber particle core 4b and a coating layer 4c covering the surface of the rubber particle core 4b. Furthermore, the coating layer 4c is preferably a resin layer or a surface modification layer of the rubber particle core 4b. This improves the dispersibility of the resin composition to the thermosetting resin layer 3 before thermosetting. In this case, the rubber particle core 4b can be formed using the aforementioned material. Regarding the resin layer and the surface modification layer, any resin layer and surface modification layer can be used as long as it improves the dispersibility of the resin composition. Such rubber particles 4 (4a) are commercially available as core-shell rubber (CSR) and can be appropriately selected and used in the lamination of the soft magnetic material 2 and the iron core 1 in this embodiment.

[0053] Furthermore, regarding the content of rubber particles 4 dispersed in the thermosetting resin layer 3, when the content of the thermosetting resin is 100 phr, it is preferable to exceed 0 phr and be less than 8 phr. Here, phr is short for per hundred resin, a unit representing the amount of other materials (rubber particles 4) mixed when the weight of the resin is 100. phr is sometimes also expressed as parts by weight. When the content of rubber particles 4 is within this range, the adhesion between adjacent soft magnetic materials 2 can be further improved by the rubber particles 4 dispersed in the layer. From the viewpoint of improving adhesion, the more rubber particles 4 in this range, the better. However, even within this range, as the content of rubber particles approaches the upper limit, the aggregation of rubber particles 4 is prone to occur. When the aggregation of rubber particles 4 occurs, the surface becomes uneven, thus deteriorating the feel and appearance, or increasing the thickness of the thermosetting resin layer 3. Therefore, to suppress these problems, the content of rubber particles 4 is preferably less than 8 phr, 7 phr or less, 6 phr or less, or 5 phr or less when the content of thermosetting resin is 100 phr. On the other hand, to improve adhesion, the content of rubber particles 4 is preferably 1 phr or more, 2 phr or more, or 3 phr or more when the content of thermosetting resin is 100 phr. The most preferred content of rubber particles 4 is 4 phr when the content of thermosetting resin is 100 phr.

[0054] (Manufacturing method of iron core 1)

[0055] Next, the manufacturing method of the iron core 1 in this embodiment will be described.

[0056] The manufacturing method of the iron core 1 in this embodiment includes a first step of preparing a resin composition that is liquid at room temperature by dispersing rubber particles 4; a second step of coating the prepared resin composition onto the surface of a soft magnetic material 2; a third step of stacking the soft magnetic material 2 plates coated with the resin composition, and then heating them in this state until the resin composition is cured to form a thermosetting resin layer 3 and holding them thereafter; and a fourth step of processing the laminate with the thermosetting resin layer 3 into the iron core 1.

[0057] The first step is carried out according to a general preparation method corresponding to the resin composition. In addition, in the first step, rubber particles 4 are added to and dispersed in the resin composition. The addition and dispersion of the rubber particles 4 to the resin composition can be carried out using appropriate methods such as stirring with a stirrer, mechanical dispersion by shearing, or stirring by ultrasound, depending on the dispersibility of the rubber particles 4 and the viscosity of the resin composition.

[0058] In the second process, the soft magnetic material 2 is coated on the surface of the resin material 2 according to the required thickness of the resin composition and the thermosetting resin layer 3 formed, using a wire bar coater or slot coater, reverse printing, screen printing, etc.

[0059] In the second step, the soft magnetic material 2 is laminated onto a resin composition coated on its surface to create a laminate. During this second step, the laminated soft magnetic material 2 can be pressurized using a press and rollers as needed. Furthermore, in the second step, a resin composition can be further coated onto the laminated soft magnetic material 2 as needed to further laminate the soft magnetic material 2. That is, the number of laminations in the second step is not particularly limited and can be performed as needed.

[0060] In the third step, the laminated body prepared above is placed in a constant temperature bath to maintain the temperature at which the resin composition hardens, thereby hardening the resin composition. When the resin composition hardens, it becomes a thermosetting resin layer 3 containing dispersed rubber particles 4, which can bond and retain the soft magnetic material 2.

[0061] In addition, in this embodiment, the second and third processes can be repeated any number of times as needed to form a thicker laminate.

[0062] In the fourth step, the laminated and bonded body is machined by punching or other mechanical processes into a shape corresponding to its application, becoming the core 1 of this embodiment.

[0063] The iron core 1 of this embodiment described above can be used in larger applications requiring high efficiency, such as iron cores for motor vehicles or transformers, and also in applications requiring heat resistance. Furthermore, the iron core 1 of this embodiment is not limited to these applications and can also be used in current sensors or noise countermeasures in household appliances and industrial appliances.

[0064] The iron core 1 described above can be bonded to adjacent soft magnetic materials 2 with high adhesion using a thermosetting resin layer 3 in which rubber particles 4 are dispersed. In this embodiment, because the soft magnetic materials 2 are bonded with high adhesion in this way, the soft magnetic materials 2 are not easily peeled off even when punching or other processes are performed during the shaping of the iron core 1.

[0065] Furthermore, the core 1 in this embodiment uses a thermosetting resin that does not melt or dissolve due to the curing reaction progressing with heating. On the other hand, there are also cases, as described in Patent Document 1, where a thermoplastic resin that becomes malleable by heating and then hardens again upon cooling is used.

[0066] When using thermoplastic resins, it is necessary to melt the resin, which has a higher melting point than the required heat resistance for the iron core (e.g., 180°C), and bond it to the soft magnetic material. Therefore, a high-temperature (approximately 180–250°C) bonding process is required, making production difficult.

[0067] In contrast, the core 1 of this embodiment uses a thermosetting resin, so when bonding the soft magnetic material 2, it is only necessary to heat it to a temperature that allows a cross-linking reaction to occur (this temperature is lower than the temperature required for the heat resistance of the core 1, and is around 120 to 170°C), making it easy to manufacture.

[0068] Furthermore, thermoplastic resins have higher viscosity compared to thermosetting resins, making it difficult to thin the resin layer (thermoplastic resin layer). Therefore, it is impossible to increase the number of layers of soft magnetic material per unit volume, thus hindering the improvement of the core's performance.

[0069] On the other hand, in this embodiment, the core 1 is formed using a thermosetting resin with lower viscosity than thermoplastic resin to form a thermosetting resin layer 3, thus allowing for a thinner layer thickness. Therefore, the number of layers of soft magnetic material 2 per unit volume can be increased, improving the performance of the core 1.

[0070]

Example

[0071] Next, embodiments and comparative examples are shown, and the iron core of this embodiment will be described in further detail. However, the scope of the present invention is not limited thereto.

[0072] The materials used in the examples and comparative examples are shown below. Additionally, regarding the rubber granules used herein, according to the manufacturer's specifications, they are methacrylic acid-butadiene-styrene (MBS) rubber with an average particle size of 190 nm.

[0073] Thermosetting resin: Epoxy resin (Mitsubishi Chemical Corporation, JER-828)

[0074] Hardener: Acid anhydride (Hitachi Chemical Co., Ltd., HN-2200)

[0075] Hardening catalyst: Imidazole compounds (Shikoku Chemical Industry Co., Ltd., 2E4Mz-CN)

[0076] Rubber granules: Multi-layered rubber granules (Dow Japan Holdings, BTA-731)

[0077] The materials for each component of the comparative examples, Examples 1 and 2 shown in Table 1 were weighed in glass bottles and stirred at room temperature. They were then placed in a vacuum dryer at room temperature for vacuum degassing.

[0078] During vacuum degassing, the resin composition of the comparative example was kept under vacuum until the bubbles disappeared. For the resin compositions of Examples 1 and 2, in order to remove the air trapped in the rubber particles, the operation of restoring the vacuum state to normal pressure was performed multiple times until the trapped air was eliminated.

[0079] In Table 1, "-" indicates that there is no corresponding item.

[0080] Table 1

[0081]

[0082] The resin compositions prepared in this manner for Comparative Examples 1 and 2 were applied to the surface of an amorphous alloy (Hitachi Metals Corporation, 2605SA1) using a wire bar coater (RDSPECIALTIES, No. 5). In this study, the surface of the amorphous alloy was not specially cleaned or otherwise treated, and it was used in its original, post-purchase condition.

[0083] Next, the amorphous alloy, coated with each resin component, is bonded together in a manner that prevents air bubbles from entering. It is then sandwiched between 5mm thick SUS plates that have undergone demolding treatment and heated at 150°C for 1 hour.

[0084] After cooling, the laminated amorphous alloy was removed from between the SUS plates, and each resin component was applied again to the surface of the laminated amorphous alloy using a wire bar coater. Then, the operation of clamping the laminated amorphous alloy between the SUS plates that had undergone demolding and heating it at 150°C for 1 hour was repeated to confirm that samples (laminated bodies) of the cores of Comparative Examples 1 and 2, which were laminated and bonded as described above, could be manufactured.

[0085] The adhesion of the core samples from Comparative Examples 1 and 2 was evaluated as described below. Furthermore, the heat resistance of the thermosetting resin layer of the core samples from Comparative Examples 1 and 2 was evaluated as described below.

[0086] (Adhesiveness)

[0087] Figure 4 This is a schematic cross-sectional view showing the structure of the test piece used to evaluate adhesion. When evaluating adhesion, such as... Figure 4 As shown, an adhesive 42 (ThreeBond, TB1360) was applied to a 25mm × 100mm × 2mm SPCC (cold-rolled steel sheet) sheet 41 used as a substrate using a wire rod coater (RDSPECIALTIES, No. 5). Next, a 25mm × 100mm amorphous alloy 43 (Hitachi Metals Corporation, 2605SA1) was overlapped thereon and cured at room temperature for 1 day for bonding. Two portions of this product were prepared. Next, on a portion of one side of the amorphous alloy 43 of the SPCC sheet 41 to which the amorphous alloy 43 was bonded, one of the resin compositions 44 shown in Table 1 was applied. The coating area of ​​the resin composition 44 was set to 25mm × 50mm. Next, for the portion coated with the resin composition 44, the amorphous alloy 43 of the SPCC sheet 41 to which the other amorphous alloy 43 was bonded was bonded in a manner opposite to it. Then, the resin composition 44 was hardened by heating at 150°C for 1 hour, and a product was made as shown. Figure 4 The test piece 46 shown has a thermosetting resin layer 45.

[0088] Then, the test piece 46 was stretched using a tensile testing machine (Shimadzu Corporation, AG-100kNX) at a tensile speed of 30 mm / min, and its maximum breaking strength was determined and used as the adhesive strength.

[0089] (Heat resistance)

[0090] After demolding, an arbitrary amount of the resin composition of the comparative examples, Example 1, and Example 2 shown in Table 1 was filled into an aluminum cup. The cup was then heated at 150°C for 1 hour to produce a sheet with a thermosetting resin layer. The sheet was then cut into pieces approximately 5mm × 5mm × 1mm in size as test pieces.

[0091] Then, for the test piece, thermogravimetric analysis was performed using a thermogravimetric analyzer (TA Instrument, Q500) in an air flow (10 mL / min) within a temperature range of 100°C to 500°C, with a heating rate of 10°C / min. The temperature at which the mass decreases by 5% relative to the initial mass is reduced by 5% is defined as the heat resistance.

[0092] Table 2 shows the rubber particle content (referred to as "rubber particle content" only) and adhesive strength when the thermosetting resin content is 100 phr. Additionally, Table 2 also lists the 5% mass reduction temperature as an evaluation result of heat resistance, and opinions on the visually confirmed uniformity of the rubber particles. Furthermore, "-" in Table 2 indicates that since no rubber particles are present, there is no opinion on the uniformity of the rubber particles. Regarding opinions related to the uniformity of the rubber particles, "Good" indicates that no agglomeration was observed and the surface is smooth, while "Agglomeration" indicates that agglomeration was observed and the surface is uneven.

[0093] Table 2

[0094]

[0095] Regarding adhesion, the test pieces of Comparative Examples and Examples 1 and 2 did not experience delamination between the layers of the soft magnetic material (amorphous alloy) and showed good adhesion. However, as shown in Table 2, Examples 1 and 2, because they contained rubber particles dispersed in the thermosetting resin layer, exhibited significantly improved adhesion strength compared to the Comparative Examples which did not contain rubber particles. Therefore, it has been confirmed that adding rubber particles is very effective in improving adhesion when using thermosetting resin for bonding soft magnetic materials.

[0096] In addition, in Example 1, the content of rubber particles is appropriate (4 phr when the content of thermosetting resin is 100 phr), so not only is the adhesion high, but the surface is also smooth.

[0097] On the other hand, in Example 2, the rubber particle content was 8 phr when the thermosetting resin content was 100 phr. Therefore, although the adhesion was highest, agglomeration occurred, resulting in an uneven surface and slightly poor uniformity of the rubber particles. This is presumably due to the agglomeration of rubber particles. Furthermore, the heat resistance was slightly lower in Example 2 compared to Example 1. This is presumably because deterioration progressed in the agglomerated areas of the rubber particles. Based on these observations, it is considered that Example 2 is sufficient when adhesion is important. However, considering the appearance and heat resistance of the iron core, it is preferable that the rubber particle content when the thermosetting resin content is 100 phr is less than 8 phr, and more preferably 7 phr or less, 6 phr or less, or 5 phr or less. Furthermore, the higher the rubber particle content, the higher the adhesion; therefore, it is considered that the rubber particle content when the thermosetting resin content is 100 phr is preferably more than 0 phr, and more preferably 1 phr or more, 2 phr or more, or 3 phr or more.

[0098] Based on the above results, it is shown that dispersing rubber particles in a thermosetting resin layer is effective for laminating, bonding, and forming a core of soft magnetic materials.

[0099] Furthermore, based on the above results, Examples 1 and 2 demonstrated the effectiveness of resin compositions using epoxy resin as the thermosetting resin and anhydride compounds as the curing agent. However, it is believed that compounds other than anhydride compounds can also be used as curing agents. Additionally, it is believed that unsaturated polyester resins or acrylic resins can also be used as thermosetting resins other than epoxy resins.

[0100] Furthermore, according to this embodiment, it is possible to improve adhesion while reducing the stress applied to the foil, thereby preventing increased loss of new soft magnetic materials such as amorphous alloys and nanocrystalline alloys.

[0101] The embodiments and examples of the iron core of the present invention have been described in detail above, but the spirit of the present invention is not limited thereto, and various modifications are included. For example, the above embodiments are described in detail for the purpose of easily understanding the present invention, and are not limited to having all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of a certain embodiment. Furthermore, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0102] Explanation of reference numerals in the attached figures

[0103] 1 Iron core

[0104] 2. Soft magnetic materials

[0105] 3. Thermosetting resin layer

[0106] 4,4a rubber granules

[0107] 4b Rubber granule core

[0108] 4c coating layer

[0109] 41 SPCC sheet

[0110] 42 Adhesives

[0111] 43 Amorphous alloy

[0112] 44 Resin Composition

[0113] 45. Thermosetting resin layer

[0114] 46. ​​Test pieces.

Claims

1. A core, characterized in that: It includes multiple foil-shaped soft magnetic materials stacked together with layers of thermosetting resin. The thermosetting resin layer is composed of thermosetting resin and rubber particles, wherein the rubber particles are dispersed in the thermosetting resin layer. The size of the rubber particles is smaller than the thickness of the thermosetting resin layer, less than 1 μm. The thickness of the soft magnetic material is less than 50 μm. The thickness of the thermosetting resin layer is thinner than the thickness of the soft magnetic material. The thermosetting resin layer and the soft magnetic material have a processed surface formed by punching while being stacked.

2. The iron core as described in claim 1, characterized in that: The content of the rubber particles is greater than 0 phr and less than 8 phr when the content of the thermosetting resin is 100 phr.

3. The iron core as described in claim 1, characterized in that: The content of the rubber particles is between 3 phr and 5 phr when the content of the thermosetting resin is 100 phr.

4. The iron core as described in claim 1, characterized in that: The thermosetting resin layer is epoxy resin, unsaturated polyester resin, or acrylic resin.

5. The iron core as described in claim 1, characterized in that: The rubber particles are butadiene rubber, acrylic rubber, methacrylic rubber, silicone rubber, styrene rubber, or copolymers or mixtures of these rubbers, methacrylic-butadiene-styrene rubber, acrylic-butadiene-styrene rubber, or fluororubber.

6. The iron core as described in claim 1, characterized in that: The rubber particle includes a rubber particle core and a coating layer covering the surface of the rubber particle core.

7. The iron core as described in claim 6, characterized in that: The coating layer is a resin layer or a surface-modified layer of the rubber particle core.

8. The iron core as described in any one of claims 1 to 7, characterized in that: The soft magnetic material is an amorphous alloy.

9. The iron core as described in any one of claims 1 to 7, characterized in that: The soft magnetic material is a nanocrystalline alloy.

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