iron core

Abstract

To provide an iron core in which layers of a plurality of tabular soft magnetic materials are adhered with high adhesiveness.SOLUTION: An iron core 1 concerning the present invention comprises a plurality of tabular soft magnetic materials 2 laminated via thermosetting resin layers 3, and rubber particles 4 are distributed in the thermosetting resin layers 3. The content of the rubber particles 4 preferably exceeds 0 phr and is equal to or less than 8 phr when the content of thermosetting resin is 100 phr. The thermosetting resin layers 3 are preferably epoxy resin, unsaturated polyester resin or acrylic resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an iron core using adhesively laminated soft magnetic materials. [Background technology]

[0002] In recent years, efforts to reduce CO2 emissions have become more common due to environmental issues such as global warming. One such effort is the widespread adoption of electric vehicles (xEVs), such as electric and hybrid vehicles. The motors used in xEVs are required to be even more efficient, and similarly, transformers are also required to have improved conversion efficiency. This has led to active development of soft magnetic materials aimed at reducing loss in the iron cores used in motor stators, rotors, and transformers.

[0003] Currently, electromagnetic steel sheets are the mainstream soft magnetic material used in these cores, and the above-mentioned cores are formed by laminating these plate-shaped electromagnetic steel sheets. Development of new soft magnetic materials, such as amorphous alloys and nanocrystalline alloys, is underway as materials with high magnetic permeability, low iron loss, and other properties that improve efficiency.

[0004] These new soft magnetic materials are manufactured by melting metals of a given composition, homogenizing the molten metal, spreading the homogenized molten metal on a metal plate or roll, and then rapidly cooling and casting it. Therefore, these soft magnetic materials are manufactured as foil strips with a thickness of about several tens of micrometers. In contrast, the thickness of conventional soft magnetic materials, such as electromagnetic steel sheets, is several hundred micrometers, so the new soft magnetic materials described above are much thinner than conventional soft magnetic materials.

[0005] Therefore, when using the new soft magnetic material to form the core of a motor or transformer, more layers are required than with electromagnetic steel sheets. Furthermore, because the new soft magnetic material is thinner than electromagnetic steel sheets, it has lower resistance to deflection and bending due to its own weight. Therefore, when using the new soft magnetic material, care must be taken to prevent deflection and bending during and after lamination in the core formation process.

[0006] For this reason, when using new soft magnetic materials in iron cores, it is possible to bond foil strips of the soft magnetic material together with a resin of your choice so that the material itself is resistant to bending and flexing. Furthermore, iron cores for motors and transformers are expected to be able to withstand the heat generated during use.

[0007] Under these circumstances, a technology described in Patent Document 1 has been proposed. Patent Document 1 describes that at least a part of the magnetic material of a rotor or a stator is composed of a laminate made of amorphous metal magnetic thin ribbons. Patent Document 1 also describes that the magnetic material is composed of amorphous metal magnetic thin ribbon layers and thermoplastic resin layers alternately laminated together.

[0008] Patent Document 2 also proposes a technology. Patent Document 2 describes that in a magnetic core formed by winding an amorphous magnetic foil strip, resin is filled in after each of several windings of the magnetic foil strip. Patent Document 2 also describes that the resin is filled in via a spacer after each of several windings of the magnetic foil strip. Patent Document 2 also describes that a thermoplastic resin or a thermosetting resin is used as the resin, and that silica or alumina may be included to improve heat conduction. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-048859 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-91932 Summary of the Invention [Problem to be solved by the invention]

[0010] However, since the technology described in Patent Document 1 simply uses a thermoplastic resin, there is a possibility that the iron core manufactured using this technology may not have sufficient adhesiveness to the magnetic material. Furthermore, the technology described in Patent Document 2 involves filling resin into the magnetic foil strip after each of several windings, and also involves filling resin through a spacer after each of several windings, which may result in insufficient adhesion of the magnetic foil strip.

[0011] An object of the present invention is to provide an iron core in which a plurality of layers of plate-shaped soft magnetic material are bonded together with high adhesiveness. [Means for solving the problem]

[0012] The iron core according to the present invention, which solves the above-mentioned problems, comprises a plurality of foil strip-shaped soft magnetic materials laminated with thermosetting resin layers interposed therebetween, and rubber particles are dispersed in the thermosetting resin layers, The size of the rubber particles is smaller than the thickness of the thermosetting resin layer, 1 μm or less; The soft magnetic material is Thickness is 50 μm or less Amorphous or nanocrystalline alloys The thickness of the thermosetting resin layer is thinner than the thickness of the soft magnetic material, and the thermosetting resin layer and the soft magnetic material have processed surfaces formed by being punched in a laminated state. It is intended to do so. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an iron core in which a plurality of layers of plate-shaped soft magnetic material are bonded together with high adhesiveness. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a schematic perspective view showing an example of an iron core according to the present embodiment. [Figure 2] FIG. 2 is a partially enlarged cross-sectional view illustrating the laminated structure of the iron core according to the embodiment. [Figure 3] FIG. 2 is a cross-sectional view showing the configuration of a rubber particle that can be suitably used in the present embodiment. [Figure 4] FIG. 2 is a schematic cross-sectional view showing the configuration of a test piece used to evaluate adhesiveness. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of an iron core according to the present invention will be described in detail below with reference to the accompanying drawings as appropriate. Here, FIG. 1 is a schematic perspective view showing an example of an iron core 1 according to this embodiment. FIG. 2 is a partially enlarged cross-sectional view illustrating the laminated structure of the iron core 1 according to this embodiment. FIG. 3 is a cross-sectional view showing the configuration of rubber particles 4 that can be suitably used in this embodiment. Note that in these figures, the shapes and dimensions of each element are exaggerated for ease of viewing and explanation.

[0016] (Iron core 1) The iron core 1 shown in Fig. 1 is a stator of a motor, as an example. However, the iron core 1 may also be a rotor. As shown in Fig. 2, the iron core 1 according to this embodiment includes, for example, a plurality of plate-shaped soft magnetic materials 2 laminated with thermosetting resin layers 3 interposed therebetween. The thermosetting resin layers 3 have rubber particles 4 dispersed within them.

[0017] (Soft magnetic material 2) The soft magnetic material 2 can be produced in the form of a foil strip, for example, by melting a metal of any composition, spreading the homogenized molten metal on a metal plate or metal roll, and then rapidly cooling and casting it. The soft magnetic material 2 produced in this manner is an amorphous soft magnetic material (amorphous alloy) and has low loss. The soft magnetic material 2 may also be produced by, for example, heat-treating the foil strip-shaped soft magnetic material 2 obtained in this manner to microcrystallize it and control the domain walls. A soft magnetic material 2 that has undergone such heat treatment is called a nanocrystalline soft magnetic material (nanocrystalline alloy). The metal composition of these soft magnetic materials 2 is not particularly limited as long as it is produced by the above-mentioned production method, but alloys mainly composed of iron, silicon, and boron, or alloys to which phosphorus, copper, etc. are added, can be used.

[0018] The thickness of the soft magnetic material 2 is not particularly limited, but as described above, it is produced by melting a metal of any composition, spreading the homogenized molten metal on a metal plate or metal roll, and then performing ultra-rapid casting, so that the thickness is generally from several μm to 50 μm.

[0019] (Thermosetting resin layer 3) The thermosetting resin layer 3 is made of a resin composition that is liquid at room temperature before curing. In this embodiment, a resin composition with a lower viscosity is preferable. Examples of such a resin composition include an epoxy resin composition, an unsaturated polyester resin composition, and an acrylic resin composition. These resin compositions can be used to form the thermosetting resin layer 3.

[0020] The epoxy resin composition can be a mixture of an epoxy resin and any curing agent. Any epoxy resin can be selected depending on the heat resistance and adhesiveness. Examples of epoxy resins that can be used include, but are not limited to, bis-A epoxy resins, bis-F epoxy resins, and phenol novolac epoxy resins.

[0021] The curing agent may be any of those commonly used as curing agents for epoxy resins, including, for example, acid anhydrides such as maleic anhydride, phthalic anhydride, and tetrahydrophthalic anhydride, aliphatic amines such as diethylenetriamine, triethylenetetramine, diaminodiphenylmethane, and diaminodiphenylsulfone, polyamines, and aromatic amines.

[0022] A catalyst can be selected and applied as desired depending on the curing temperature of the epoxy resin composition. Examples of such catalysts include compounds having an imidazole structure, such as 2-methylimidazole.

[0023] The curing agents and catalysts that can be used to harden these epoxy resin compositions are not limited in any way in terms of the types of materials contained therein and their composition ratios, as long as the epoxy resins are liquid at room temperature and can be applied to the soft magnetic material 2. Any curing agent and catalyst, including commercially available ones, can be used for curing these epoxy resin compositions, as long as they perform their functions.

[0024] The unsaturated polyester resin composition may be a mixture of a vinyl ester resin, an optional curing agent, and an optional reaction initiator. Examples of the curing agent used include reactive diluents, such as vinyl monomers such as styrene and vinyl toluene, and acrylic acid ester monomers and methacrylic acid ester monomers such as methyl methacrylate. Examples of the reaction initiator used in this case include thermal radical generators, such as azo compound derivatives such as 2,2'-azobisbutyronitrile and organic peroxides such as benzoyl peroxide.

[0025] The curing agent and reaction initiator that can be used to harden these unsaturated polyester resin compositions are not limited in any way in terms of the types of materials contained therein and their composition ratios, as long as the unsaturated polyester resin composition is liquid at room temperature and in a state that can be applied to the soft magnetic material 2. As with the epoxy resins described above, any curing agent and reaction initiator can be used to cure these unsaturated polyester resin compositions, including commercially available ones, as long as they perform their functions.

[0026] The acrylic resin composition can be a mixture of any acrylic acid ester monomer and any methacrylic acid ester monomer, such as ethyl acrylate, hydroxyethyl acrylate, or methyl methacrylate, mixed in any ratio. Acrylic resins are synthesized by addition polymerization (radical polymerization) using radical species as a reaction initiator. Examples of reaction initiators include thermal radical generators. Examples of thermal radical generators that can be used include azo compound derivatives such as 2,2'-azobisbutyronitrile and organic peroxides such as benzoyl peroxide. As with the epoxy resins described above, any initiator can be used for curing the acrylic resin composition, including commercially available ones, as long as it functions as such.

[0027] Although there are no particular limitations on the thickness of the thermosetting resin layer 3, it is desirable that in the iron core 1 according to this embodiment, the thickness is thinner than the thickness of the soft magnetic material 2. This allows for a larger number of layers of the soft magnetic material 2 per given volume, thereby improving the performance of the iron core 1.

[0028] (Rubber particles 4) As described above, the thermosetting resin layer 3 has rubber particles 4 dispersed therein. The presence of the rubber particles 4 dispersed therein reduces stress that occurs when the thermosetting resin layer 3 is sheared or peeled off, and can suppress the progression of resin failure (i.e., suppress cohesive failure). This improves the toughness of the thermosetting resin layer 3 itself, and can increase the adhesion between adjacent soft magnetic materials 2.

[0029] The size (particle diameter) of the rubber particles 4 is desirably smaller than the thickness of the thermosetting resin layer 3. In this way, the small size of the rubber particles 4 does not hinder adhesion between adjacent soft magnetic materials 2. Therefore, it is possible to increase adhesion while reducing the thickness of the thermosetting resin layer 3.

[0030] The size of the rubber particles 4 can be, for example, 10 nm or more and 1 μm or less. In this case, the size of the rubber particles 4 is sufficiently small, so that they are less likely to interfere with the adhesion between adjacent soft magnetic materials 2. In addition, the size of the rubber particles 4 is sufficiently small, so that unevenness is less likely to occur on the surface of the thermosetting resin layer 3. Furthermore, the size of the rubber particles 4 is sufficiently small, so that 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. In addition, the size of the rubber particles 4 can be 900 nm or less, 800 nm or less, 700 nm or less, or 600 nm or less.

[0031] The rubber particles 4 can be made of any material depending on the heat resistance and adhesiveness of the thermosetting resin layer 3. The rubber particles 4 are preferably made of, for example, butadiene rubber, acrylic rubber, methacrylic rubber, silicone rubber, styrene rubber, copolymers or mixtures of these rubbers, MBS (methacryl-butadiene-styrene) rubber, or ABS (acrylic-butadiene-styrene) rubber. Furthermore, to further improve heat resistance, the rubber particles 4 may be made of fluororubber, which has fluorine atoms in its molecular structure. Examples of such fluororubbers include vinylidene fluoride rubber, tetrafluoroethylene-perfluorovinyl ether rubber, and tetrafluoroethylene-propylene rubber, or mixtures of these fluororubbers with each other or with any of the above rubber particles. When the rubber particles 4 are made of these materials, their specific gravity is closer to that of the thermosetting resin than inorganic particles, allowing them to be dispersed relatively stably without settling before curing. This enhances the adhesion between adjacent soft magnetic materials 2.

[0032] As shown in FIG. 3, the rubber particles 4 are preferably multilayer rubber particles 4a having a rubber particle core 4b and a coating layer 4c covering the surface of the rubber particle core 4b. The coating layer 4c is preferably a resin layer or a surface-modified layer of the rubber particle core 4b. This enhances the dispersibility of the thermosetting resin layer 3 in the resin composition before thermal curing. In this case, the rubber particle core 4b can be formed from the materials described above. Any resin layer or surface-modified layer can be used as long as it enhances dispersibility in the resin composition. Such rubber particles 4 (4a) are commercially available as core-shell rubber (CSR), and can be appropriately selected and used for the laminations and iron core 1 of the soft magnetic material 2 in this embodiment.

[0033] Furthermore, the content of the rubber particles 4 dispersed in the thermosetting resin layer 3 is preferably greater than 0 phr and not more than 8 phr, assuming that the content of the thermosetting resin is 100 phr. Note that phr is an abbreviation for per hundred resin, and is a unit that represents the amount of other material (rubber particles 4) blended when the weight of the resin is 100. phr is also sometimes expressed as parts by weight. When the content of the rubber particles 4 is within this range, the rubber particles 4 dispersed in the layer can further improve the adhesion between adjacent soft magnetic materials 2. From the perspective of improving adhesion, the higher the content of the rubber particles 4 within this range, the more preferable it is. However, even within this range, as the content of the rubber particles approaches the upper limit, the more likely the rubber particles 4 to aggregate. Aggregation of the rubber particles 4 causes unevenness on the surface, which can result in a poor feel and appearance and an increase in 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 enhance adhesiveness, 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 content of rubber particles 4 is most preferably 4 phr, when the content of thermosetting resin is 100 phr.

[0034] (Manufacturing method of iron core 1) Next, a method for manufacturing the iron core 1 according to this embodiment will be described. The manufacturing method of the iron core 1 according to this embodiment includes a first step of preparing a resin composition that is liquid at room temperature and has rubber particles 4 dispersed therein; a second step of applying the prepared resin composition to the surface of the soft magnetic material 2; a third step of stacking sheets of the soft magnetic material 2 to which the resin composition has been applied, heating them in this state, and holding them there until the resin composition has completely hardened and the thermosetting resin layer 3 has been formed; and a fourth step of processing the laminate with the thermosetting resin layer 3 formed thereon into the iron core 1.

[0035] The first step is carried out according to a general preparation method suitable for the resin composition. In the first step, rubber particles 4 are added to the resin composition and dispersed. The addition and dispersion of the rubber particles 4 into the resin composition may be carried out by an appropriate method, such as stirring using a stirrer, mechanical dispersion by shearing, or ultrasonic stirring, depending on the dispersibility of the rubber particles 4 and the viscosity of the resin composition.

[0036] In the second step, the resin composition is applied to the surface of the soft magnetic material 2 by a bar coater, a slit coater, reverse printing, screen printing, or the like, depending on the viscosity of the resin composition and the desired thickness of the thermosetting resin layer 3 to be formed. In the second step, a soft magnetic material 2 is laminated on the resin composition applied to the surface of the soft magnetic material 2 to produce a laminate. At this time, in the second step, the laminated soft magnetic material 2 may be pressed using a press, roller, or the like, as needed. In the second step, if needed, a resin composition may be further applied on the laminated soft magnetic material 2 to laminate the soft magnetic material 2. In other words, the number of laminations in the second step is not particularly limited, and may be performed as needed.

[0037] In the third step, the laminate is placed in a thermostatic chamber maintained at a temperature at which the resin composition is cured, and the resin composition is cured. When the resin composition is cured, it becomes a thermosetting resin layer 3 in which rubber particles 4 are dispersed, and can adhere and hold the soft magnetic material 2. In this embodiment, the second and third steps may be repeated any number of times as necessary to form a thicker laminate.

[0038] In the fourth step, the laminated and bonded body is formed into a shape according to the intended use by machining such as punching, to form the iron core 1 according to this embodiment.

[0039] The iron core 1 according to the present embodiment described above can be used in applications requiring relatively large sizes and heat resistance, such as the aforementioned iron cores for automobile motors and transformers that require high efficiency. Furthermore, the iron core 1 according to the present embodiment is not limited to these applications, but can also be used in current sensors and noise suppression for household electrical appliances and industrial electrical appliances.

[0040] In the iron core 1 according to the present embodiment described above, adjacent soft magnetic materials 2 can be bonded together with high adhesiveness by the thermosetting resin layer 3 having dispersed therein rubber particles 4. In the present embodiment, the soft magnetic materials 2 are bonded together with such high adhesiveness, so that the soft magnetic materials 2 are unlikely to peel off even when punching or the like is performed to form the shape of the iron core 1.

[0041] Furthermore, the iron core 1 according to this embodiment uses a thermosetting resin that undergoes a hardening reaction when heated and becomes insoluble and infusible. On the other hand, as in the technology described in Patent Document 1, there are also techniques that use a thermoplastic resin that softens and becomes plastic when heated and hardens again when cooled. When using thermoplastic resin, it is necessary to melt the thermoplastic resin, which has a melting point higher than the heat resistance temperature (for example, 180°C) required for the iron core, and then bond it to the soft magnetic material. This requires a high-temperature (approximately 180 to 250°C) bonding process, making production difficult. In contrast, the iron core 1 of this embodiment uses a thermosetting resin, so when adhering the soft magnetic material 2, it only needs to be heated to a temperature that can cause a cross-linking reaction (this temperature is lower than the heat resistance temperature required of the iron core 1, around 120 to 170°C), making production easy.

[0042] Furthermore, because thermoplastic resins have higher viscosity than thermosetting resins, it is difficult to reduce the thickness of the resin layer (thermoplastic resin layer), which means that the number of layers of soft magnetic material per given volume cannot be increased, making it difficult to improve the performance of the iron core. On the other hand, in the iron core 1 according to this embodiment, the thermosetting resin layer 3 is formed using a thermosetting resin that has a lower viscosity than a thermoplastic resin, so the layer thickness can be made thinner. This allows the number of layers of soft magnetic material 2 per given volume to be increased, thereby improving the performance of the iron core 1. [Example]

[0043] Next, the iron core according to this embodiment will be described in more detail with reference to examples and comparative examples, although the technical scope of the present invention is not limited to these. The materials used in the examples and comparative examples are listed below. The rubber particles used here were methacrylic-butadiene-styrene (MBS) rubber with an average particle size of 190 nm, according to the manufacturer's specifications. Thermosetting resin: Epoxy resin (Mitsubishi Chemical Corporation, jER-828) Hardener: Acid anhydride (Hitachi Chemical Co., Ltd., HN-2200) Curing catalyst: Imidazole compound (Shikoku Chemicals Corporation, 2E4Mz-CN) Rubber particles: Multilayered rubber particles (Dow Japan Holdings Co., Ltd., BTA-731)

[0044] The ingredients of the comparative example, examples 1 and 2 shown in Table 1 were weighed into glass bottles and stirred at room temperature. Each of these was placed in a vacuum dryer at room temperature and vacuum degassed. In carrying out the vacuum degassing, the resin composition according to the comparative example was maintained in a vacuum state until bubbles disappeared. For the resin compositions according to Examples 1 and 2, in order to remove air entrapment by the rubber particles, the operation of maintaining the vacuum state and then returning to normal pressure was carried out multiple times until air entrapment disappeared. "-" in Table 1 indicates that there is no applicable item.

[0045] [Table 1]

[0046] The resin compositions prepared in this manner according to the Comparative Example, Examples 1 and 2 were applied to the surface of an amorphous alloy (Hitachi Metals, Ltd., 2605SA1) using a bar coater (RD SPECIALTIES, No. 5). In this study, the surface of the amorphous alloy was not particularly cleaned, and the alloy was used as purchased.

[0047] Next, an amorphous alloy was laminated onto the amorphous alloy coated with each resin composition, taking care not to trap air bubbles. This was then sandwiched between 5 mm thick release-treated SUS plates and heated at 150°C for 1 hour. After cooling, the laminated and bonded amorphous alloy was removed from between the SUS plates, and each resin composition was again applied to the surface of the laminated and bonded amorphous alloy using a bar coater.Then, the amorphous alloy was sandwiched between release-treated SUS plates and heated at 150°C for 1 hour, and this operation was repeated.It was confirmed that the iron core samples (laminates) according to the comparative example, examples 1 and 2, which were laminated and bonded as described above, could be manufactured.

[0048] The adhesiveness of the iron core samples according to the comparative example and examples 1 and 2 was evaluated as follows. Also, the heat resistance of the thermosetting resin layer of the iron core samples according to the comparative example and examples 1 and 2 was evaluated as follows.

[0049] (Adhesiveness) FIG. 4 is a schematic cross-sectional view showing the configuration of a test piece used to evaluate adhesion. To evaluate adhesion, as shown in FIG. 4, an adhesive 42 (ThreeBond, TB1360) was applied to a 25 mm × 100 mm × 2 mm SPCC (cold-rolled steel) plate 41 used as a substrate using a bar coater (RDSPECIALTIES, No. 5). A 25 mm × 100 mm amorphous alloy 43 (Hitachi Metals, Ltd., 2605SA1) was then placed on top of the adhesive and cured at room temperature for one day to bond the two plates. Two of these plates were prepared. Next, one of the resin compositions 44 listed in Table 1 was applied to a portion of one side of the amorphous alloy 43 of one of the SPCC plates 41 to which the amorphous alloy 43 was adhered. The application area of ​​the resin composition 44 was 25 mm × 50 mm. Next, the amorphous alloy 43 of another SPCC plate 41, to which an amorphous alloy 43 had been adhered, was adhered so as to face the portion to which the resin composition 44 had been applied. The plate was then heated at 150°C for 1 hour to cure the resin composition 44, thereby producing a test piece 46 having a thermosetting resin layer 45 as shown in Figure 4. Then, this test piece 46 was pulled at a pulling speed of 30 mm / min using a tensile tester (Shimadzu Corporation, AG-100kNX), and the maximum breaking strength was measured and taken as the adhesive strength.

[0050] (Heat resistance) An arbitrary amount of the resin composition according to Comparative Example, Example 1, and Example 2 shown in Table 1 was filled into a release-treated aluminum cup. This was then heated at 150°C for 1 hour to produce a plate material on which a thermosetting resin layer was formed. This plate material was then cut into a size of approximately 5 mm x 5 mm x 1 mm to prepare a test piece. Then, this test piece was subjected to thermogravimetric measurement using a thermogravimetric measuring device (TA Instrument, Q500) in the temperature range of 100°C to 500°C under an air flow (10 mL / min) at a heating rate of 10°C / min, and the 5% mass loss temperature at which the mass decreased by 5% compared to the initial mass was defined as the heat resistance.

[0051] Table 2 shows the rubber particle content (simply referred to as "rubber particle content" in Table 2) and adhesive strength when the thermosetting resin content is 100 phr. Table 2 also shows the 5% mass loss temperature as an evaluation result of heat resistance, and findings regarding the uniformity of the rubber particles as confirmed by visual inspection. Note that "-" in Table 2 indicates that no findings regarding the uniformity of the rubber particles were found because no rubber particles were contained. Regarding findings regarding the uniformity of the rubber particles, "good" indicates that no agglomeration was observed and the surface was smooth, and "agglomeration" indicates that agglomeration was observed and the surface was uneven.

[0052] [Table 2]

[0053] Regarding adhesion, the test pieces according to the comparative example and examples 1 and 2 all showed good adhesion without any peeling between the layers of soft magnetic material (amorphous alloy). However, as shown in Table 2, examples 1 and 2 contained rubber particles dispersed in the thermosetting resin layer, and therefore had significantly higher adhesive strength than the comparative example, which did not contain rubber particles. This confirmed that adding rubber particles when using a thermosetting resin to bond soft magnetic materials is extremely effective in improving adhesion.

[0054] In addition, in Example 1, the content of rubber particles was appropriate (4 phr when the content of thermosetting resin was 100 phr), so not only was the adhesiveness high but the surface was also smooth. On the other hand, in Example 2, the rubber particle content was 8 phr when the thermosetting resin content was 100 phr, so although the adhesiveness was the highest, aggregation occurred, resulting in an uneven surface and slightly inferior rubber particle uniformity. This is presumably due to the agglomeration of rubber particles. Furthermore, Example 2 also exhibited slightly lower heat resistance compared to Example 1. This is presumably due to the progress of deterioration in the areas where the rubber particles aggregated. Based on these findings, Example 2 is recommended when adhesiveness is important. However, when the appearance and heat resistance of the core are taken into consideration, it is preferable to set the rubber particle content to less than 8 phr when the thermosetting resin content is 100 phr, and more preferably 7 phr or less, 6 phr or less, or 5 phr or less. Furthermore, since the adhesiveness increases as the rubber particle content increases, it is preferable that the rubber particle content exceed 0 phr when the thermosetting resin content is 100 phr, and it is more preferable that the rubber particle content be 1 phr or more, 2 phr or more, or 3 phr or more.

[0055] The above results show that dispersing rubber particles in a thermosetting resin layer is effective for laminating and bonding soft magnetic materials to form an iron core. Furthermore, from the above results, although the effects were demonstrated in Examples 1 and 2 using resin compositions in which an epoxy resin was used as the thermosetting resin and an acid anhydride compound was used as its curing agent, it was believed that compounds other than acid anhydride compounds could also be used as curing agents. Furthermore, it was believed that unsaturated polyester resins and acrylic resins could also be used as thermosetting resins other than epoxy resins. Furthermore, according to this embodiment, it is possible to improve adhesion and at the same time reduce the stress applied to the foil material, thereby preventing an increase in loss in new soft magnetic materials such as amorphous alloys and nanocrystalline alloys.

[0056] Although the iron core according to the present invention has been described in detail above through embodiments and examples, the gist of the present invention is not limited to these and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0057] 1 iron core 2 Soft magnetic materials 3 Thermosetting resin layer 4, 4a Rubber particles 4b Rubber particle core 4c coating layer 41 SPCC plate material 42 Adhesive 43 Amorphous alloy 44 Resin composition 45 Thermosetting resin layer 46 test specimens

Claims

1. a plurality of foil strip-shaped soft magnetic materials laminated with thermosetting resin layers interposed therebetween; 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, 1 μm or less; the soft magnetic material is an amorphous alloy or a nanocrystalline alloy having a thickness of 50 μm or less; the thickness of the thermosetting resin layer is smaller than the thickness of the soft magnetic material; The iron core is characterized in that the thermosetting resin layer and the soft magnetic material have machined surfaces formed by punching these layers in a laminated state.

2. 2. The iron core according to claim 1, wherein the content of the rubber particles is more than 0 phr and not more than 8 phr when the content of the thermosetting resin is taken as 100 phr.

3. 2. The iron core according to claim 1, wherein the thermosetting resin layer is an epoxy resin, an unsaturated polyester resin, or an acrylic resin.

4. The iron core according to claim 1, characterized in that the rubber particles are butadiene rubber, acrylic rubber, methacrylic rubber, silicone rubber, styrene rubber, or a copolymer or mixture of these rubbers, methacrylic-butadiene-styrene rubber, acrylic-butadiene-styrene rubber, or fluororubber.

5. 2. The iron core according to claim 1, wherein the rubber particles have a rubber particle core and a coating layer that coats the surface of the rubber particle core.

6. 6. The iron core according to claim 5, wherein the coating layer is a resin layer or a surface-modified layer of the rubber particle core.

Images