Stacked magnetic material, transformer core, and method for manufacturing stacked magnetic material

Abstract

Provided are a laminated magnetic material, a core for a transformer, and a method for manufacturing a laminated magnetic material, which are advantageous for ensuring heat resistance and reliability and maintain excellent magnetic properties. A laminated magnetic material in which Fe-based soft magnetic rapidly quenched alloy ribbons are layer-bonded with a thermosetting or room-temperature curable resin, wherein the resin has a glass transition temperature measured by a differential scanning calorimeter of 110°C or lower, the peel strength of the laminated magnetic material in a 180° peel test method at room temperature is 0.5 gf / mm or more, and the magnetic flux density B80 at an applied magnetic field of 80 A / m in the longitudinal direction is 1.25 T or more.

Description

Technical Field

[0001] The present invention relates to a laminated magnetic material, a core for a transformer, and a method for manufacturing the laminated magnetic material.

Background Art

[0002] CO 2 In the global trend of emission reduction, higher efficiency of transformers is required. In response to such requirements, soft magnetic rapidly quenched alloy ribbons with lower loss characteristics than grain-oriented electrical steel sheets have attracted attention, and for example, their application to cores for distribution transformers is expected. By the way, while the thickness of electrical steel sheets is about 0.20 to 0.35 mm, the thickness of soft magnetic rapidly quenched alloy ribbons is about 25 μm. Therefore, when manufacturing a core (iron core) of the same size as an electrical steel sheet using a soft magnetic rapidly quenched alloy ribbon, the number of laminations required is more than 10 times, and there has been a problem that the burden on the core manufacturing process is excessive. To solve this problem, for example, as disclosed in Patent Document 1, studies have been made to adhere and laminate a plurality of soft magnetic rapidly quenched alloy ribbons into a plate shape to enable the same handling as an electrical steel sheet.

[0003] However, even in that case, there has been a problem that the magnetic properties of the soft magnetic rapidly quenched alloy ribbon deteriorate due to the adhesive stress generated between the resin (adhesive) and the soft magnetic rapidly quenched alloy ribbon. Therefore, as disclosed in Patent Document 2, attempts have been made to reduce the load on the soft magnetic rapidly quenched alloy ribbon and suppress the deterioration of magnetic properties by using a soft resin (adhesive) with a durometer hardness of D60 or less, such as a polyester resin. Here, the durometer hardness is the hardness of a sample measured with a durometer (rubber hardness meter).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the temperature rise during use of the transformer core cannot be avoided, and thermoplastic resins such as the hot-melt type polyester resin described in Patent Document 2 were not considered to have sufficient heat resistance and long-term reliability. Therefore, a new technology for preventing deterioration of magnetic properties has been demanded.

[0006] In view of the above problems, an object of the present invention is to provide a laminated magnetic material, a transformer core, and a method for manufacturing a laminated magnetic material that are excellent in heat resistance, advantageous for ensuring reliability, and maintain excellent magnetic properties.

Means for Solving the Problems

[0007] The laminated magnetic material of the present invention is a laminated magnetic material in which Fe-based soft magnetic rapidly quenched alloy thin strips are At least one of an epoxy resin, an epoxy-modified silicone resin, and an acrylic resin, which is thermosetting or curable at room temperature interlayer-bonded with a resin, wherein the resin has a glass transition temperature measured by a differential scanning calorimeter of 110°C or less, 180° the peel strength of the laminated magnetic material in the peel test method is At room temperature 0.5 gf / mm or more 0.8 gf / mm or more under a high temperature of 75 °C and the magnetic flux density B80 at an applied magnetic field of 80 A / m in the longitudinal direction is 1.25 T or more, and it is a laminated magnetic material.

[0008] Further, the manufacturing method of the present invention is a method for manufacturing a laminated magnetic material in which Fe-based soft magnetic rapidly quenched alloy thin strips are interlayer-bonded with a thermosetting or room-temperature curable At least one of an epoxy resin, an epoxy-modified silicone resin, and an acrylic resin resin, wherein the step of adjusting the magnetic flux density B80 at an applied magnetic field of 80 A / m in the longitudinal direction of the soft magnetic rapidly quenched alloy thin strip to 1.4 T or more, First and the step of applying the resin to one or both sides of the soft magnetic rapidly quenched alloy thin strip, wherein the resin has a glass transition temperature measured by a differential scanning calorimeter of 110°C or less, and the step of laminating the soft magnetic rapidly quenched alloy thin strips and curing the resin Second and the step of the After the second step soft magnetic rapidly quenched alloy thin strips are laminated and the resin is curedThird Engineering, by means of, Let the thickness of the resin in the laminated magnetic material be h 1 [μm], the thickness of the soft magnetic rapidly quenched alloy ribbon in the laminated magnetic material be h 2 [μm], the flexural modulus of elasticity of the resin at room temperature curing be γ [MPa], the linear thermal expansion coefficient of the resin evaluated at 40 to 50 °C be α 1 [1 / °C], the linear thermal expansion rate of the soft magnetic rapidly quenched alloy ribbon be α 2 [1 / °C], the curing temperature applied to the resin be Ta [°C], the room temperature be RT [°C], and the linear thermal shrinkage rate during curing of the resin be β. When the adhesive stress σ [MPa] represented by the following mathematical formula satisfies 2.5 MPa or less, σ = h 1 / h 2 × γ × {(α 1 -α 2 ) × (Ta - RT) + β} 180° The peel strength of the laminated magnetic material in the peel test method is At room temperature 0.5 gf / mm or more 0.8 gf / mm or more under a high temperature of 75 °C and the magnetic flux density B80 at an applied magnetic field of 80 A / m in the longitudinal direction is 1.25 T or more, which is a method for manufacturing a laminated magnetic material.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a laminated magnetic material having excellent heat resistance, being advantageous for ensuring reliability, and maintaining excellent magnetic properties.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0011] The inventors first used a laminated magnetic material in which Fe-based soft magnetic rapidly quenched alloy ribbons were laminated with a thermosetting or room-temperature curable resin as the basic structure. The Fe-based soft magnetic rapidly quenched alloy ribbon is mainly composed of Fe, that is, it has 50% by mass or more of Fe, so that a high magnetic flux density can be obtained. In addition, the soft magnetic rapidly quenched alloy ribbon can reduce iron loss. In addition, the thermosetting or room-temperature curable resin can improve the heat resistance, which is a problem with thermoplastic resins such as hot-melt type polyester resins. On the other hand, according to the study of the inventors, simply applying a thermosetting or room-temperature curable resin alone was not sufficient to satisfy the requirements in terms of reliability and magnetic properties. Therefore, by adjusting the magnetic properties of the Fe-based soft magnetic rapidly quenched alloy ribbon, selecting the resin, and reducing the adhesive stress, a new laminated magnetic material that solves the above problems was found. Hereinafter, embodiments of the present invention will be described in detail.

[0012] The resin applied in this embodiment has a glass transition temperature measured by a differential scanning calorimeter of 110 °C or less. By lowering the glass transition temperature, the stress in the bonding process is less likely to remain, and the adhesive stress can be made small. In addition, in the laminated magnetic material of this embodiment, the peel strength of the laminated magnetic material in the 180° peel test method at room temperature is defined as 0.5 gf / mm or more. This is because it is recognized as a necessary characteristic when considering handling properties and the like as a laminated magnetic material. And the laminated magnetic material of the present invention realizes a magnetic flux density B80 (hereinafter simply abbreviated as B80) of 1.25 T or more when the applied magnetic field in the longitudinal direction is 80 A / m. In this way, while maintaining the required peel strength, a high magnetic flux density can be realized as a laminated magnetic material, which is particularly useful as a core for a distribution transformer. Further, as the laminated magnetic material of the present invention, more preferably, B80 is 1.39 T or more, the iron loss P CM (hereinafter, P CM14 / 50 is denoted as) is 0.16 W / kg or less.

[0013] In the present invention, when evaluating the laminated magnetic material in terms of the soft magnetic rapidly quenched alloy ribbon portion that constitutes it, P when B80 is 1.4 T or more CM14 / 50 can be 0.26 W / kg or less. Thus, in the laminated magnetic material, it is useful to realize a configuration in which the Fe-based soft magnetic rapidly quenched alloy ribbon can be arranged without significantly deteriorating the performance it inherently has.

[0014] In the present invention, the resin to be applied is preferably at least one of, but not limited to, for example, an epoxy resin, an epoxy-modified silicone resin, and an acrylic resin.

[0015] As the epoxy resin, for example, known monofunctional epoxy resins, polyfunctional epoxy resins, etc. can be used. Specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, aliphatic type epoxy resin, glycidylamine type epoxy resin, modified epoxy resins such as urethane-modified epoxy resin and rubber-modified epoxy resin, etc. can be mentioned. These epoxy resins can be used alone or in combination of two or more.

[0016] The epoxy-modified silicone resin has a very low flexural modulus, so it can greatly reduce the adhesion stress and is preferable. The type of the epoxy-modified silicone resin can be either one in which a part of the functional groups of the modified silicone resin is replaced with an epoxy group, or one in which the epoxy resin and the modified silicone are incompatible and phase-separated to form a sea-island structure.

[0017] The acrylic resin is preferable because the curing process can be shortened due to its fast curing rate, it can be cured by a contact reaction type in which, among two-component room-temperature curing types, even if the two components are not sufficiently mixed, the reaction starts and curing occurs when the two components come into contact (honeymoon adhesion), and there are a rich variety of room-temperature curing methods such as anaerobic adhesion and photo-curing adhesion, making it easy to optimize the adhesion process.

[0018] As the room-temperature curable acrylic resin used in the present invention, second-generation acrylic resin (SGA) may also be used. SGA is a resin in which an elastomer and an acrylic monomer are graft-polymerized and cured. Although it is thermoplastic, it has high heat resistance and the adhesive strength at high temperatures is less likely to decrease. Examples of the components of the acrylic resin include polyacrylic acid and its copolymers, polyacrylic acid esters and their copolymers, polymethacrylic acid and its copolymers, polymethacrylic acid esters and their copolymers, urethane-acrylic acid copolymers, styrene-acrylic acid copolymers, and the like. These acrylic resins may be used alone or in combination of two or more.

[0019] In the present invention, the resin can be disposed by providing a step of coating one or both surfaces of the soft magnetic rapid-quenching alloy ribbon. At this time, the method of coating the resin is not particularly limited. For example, a method of coating the resin by a flexographic printing method, or a method of preparing an adhesive containing the resin and a solvent, coating the adhesive with a spray or a coater, and then evaporating the solvent can be applied. Further, after the step of coating the resin, by providing a step of laminating the soft magnetic rapid-quenching alloy ribbons and curing the resin, the laminated magnetic material of the present embodiment can be obtained. For example, when laminating, the soft magnetic rapid-quenching alloy ribbons are overlapped and crimped with a roller or the like, and then heated and cured as necessary according to the curing temperature of the resin.

[0020] As the Fe-based soft magnetic rapid-quenching alloy ribbon applied to the present embodiment, for example, an amorphous alloy or a nanocrystalline alloy can be used. In particular, the Fe-Si-B system (Si: 0 atomic % or more and 10 atomic % or less, B: 10 atomic % or more and 20 atomic % or less, the balance being Fe and impurities) has a high saturation magnetic flux density Bs [T] and is preferable. The above-described soft magnetic rapid-quenching alloy ribbon can be manufactured by using a single-roll method in which a molten alloy is poured onto the cylindrical surface of a casting roll that rotates at high speed, and is rapidly cooled at the moment it touches the surface of the casting roll to obtain a continuous ribbon. The cooling rate at this time is about 10 6It is very fast at ℃ / s and can be made into a thin strip without crystallizing the molten alloy. Generally, after being manufactured, it is slit into a predetermined dimensional width and wound into a coil.

[0021] The width of the soft magnetic rapidly quenched alloy thin strip (hereinafter also referred to as ribbon) is not particularly limited, but for example, it can be 100 mm or more. When the width of the ribbon is 100 mm or more, a practical core for a distribution transformer can be preferably manufactured. The width of the ribbon is more preferably 125 mm or more. On the other hand, the upper limit of the width of the ribbon is not particularly limited. However, for example, when the manufacturing width in the single roll method exceeds 300 mm, it may not be possible to obtain a ribbon with a uniform thickness in the width direction. As a result, due to the non-uniform shape, it may be partially embrittled or the B80 may decrease. The width of the ribbon is more preferably 275 mm or less. Also, it is possible to adjust the width by slitting the ribbon according to the required transformer characteristics.

[0022] The thickness of the soft magnetic rapidly quenched alloy thin strip is preferably 10 μm or more and 50 μm or less, and more preferably 15 μm or more and 35 μm or less. This is because if it is too thin, the mechanical strength will be impaired, and if it is too thick, it will be difficult to stably obtain an amorphous layer.

[0023] The soft magnetic rapidly quenched alloy thin strip has no anisotropy derived from the crystal structure and has no crystal grain boundaries that impede the movement of magnetic walls. Therefore, it has excellent soft magnetic properties of high magnetic permeability and low loss while having a high magnetic flux density. The soft magnetic rapidly quenched alloy thin strip preferably has a B80 of 1.4 T or more, preferably 1.48 T or more, as a single body.

[0024] It is effective as a ribbon for a transformer that the soft magnetic rapidly quenched alloy thin strip has an easy magnetization direction in the longitudinal direction of the thin strip. Therefore, in the manufacturing method of the present embodiment, as a step of obtaining the above-described soft magnetic rapidly quenched alloy thin strip, a step of adjusting B80 to 1.4 T or more is required. Specifically, for example, a method of heat treatment (tension annealing) in a stretched state, a method of heat treatment in a state where a magnetic field is applied in the longitudinal direction of the thin strip, a method of heat treatment in a state where a magnetic field is applied in the longitudinal direction of the thin strip while being stretched, etc. are suitable.

[0025] By providing a step of pre-adjusting to a high magnetic flux density in the material before interlayer bonding, it is only necessary to substantially consider the deterioration during bonding in terms of magnetic properties, and additional processing for magnetic properties can be avoided. More preferably, B80 is adjusted to 1.48 T or more.

[0026] In the present embodiment, from the viewpoint of maintaining excellent magnetic properties of the laminated magnetic material, it is preferable to increase the occupancy rate as much as possible. Specifically, it preferably has an occupancy rate of 90% or more and 99% or less. Also, the thickness of the resin layer is preferably 5 μm or less, more preferably 3.0 μm or less, and even more preferably 2.0 μm or less. On the other hand, if the resin layer is too thin, sufficient adhesive strength may not be exhibited, so 1 μm or more is preferable, and 1.5 μm or more is more preferable.

[0027] In the present embodiment, when the flexural modulus of elasticity of the resin at room temperature is γ [MPa], the linear thermal expansion coefficient of the resin evaluated at 40 to 50 °C is α 1 [1 / °C], the curing temperature applied to the resin is Ta [°C], the linear thermal shrinkage rate of the resin during curing is β [dimensionless], the thickness of the resin in the laminated magnetic material is h 1 [μm], the thickness of the soft magnetic rapidly quenched alloy ribbon in the laminated magnetic material is h 2 [μm], the linear thermal expansion rate of the soft magnetic rapidly quenched alloy ribbon is α 2 [1 / °C], and when the room temperature is RT [°C], it is preferable that the adhesive stress σ [MPa] represented by the following formula is 2.5 [MPa] or less. More preferably, the adhesive stress σ is 0.4 [MPa] or less. (Equation 1) σ = h 1 / h 2 ×γ × {(α 1 -α 2 ) × (Ta - RT) + β}

[0028] Next, an explanation will be added regarding the stress σ. When attempting to obtain a laminated magnetic material by laminating and joining soft magnetic rapidly quenched alloy ribbons with a thermosetting or room temperature curable resin, the volume decreases when the resin cures. Also, when heating and bonding, a difference in the linear thermal expansion coefficients between the soft magnetic rapidly quenched alloy ribbon and the adhesive occurs. Due to these factors, adhesive stress mainly remains in the in-plane direction with respect to the soft magnetic rapidly quenched alloy ribbon.

[0029] This adhesive stress disturbs the magnetic domain structure of the soft magnetic rapidly quenched alloy ribbon and deteriorates the magnetic properties of the soft magnetic rapidly quenched alloy ribbon. In particular, when used as a core for a distribution transformer in the commercial frequency band (50 Hz, 60 Hz), phenomena such as an increase in iron loss and a decrease in magnetic flux density when a predetermined magnetic field is applied occur. An increase in the iron loss of the core leads to a decrease in the efficiency of the transformer, and when the magnetic flux density decreases when a predetermined magnetic field is applied, a problem occurs in that the noise generated when the transformer is excited becomes large. Therefore, when using a soft magnetic rapidly quenched alloy ribbon as a core for a transformer, it is effective to control the adhesive stress generated in the soft magnetic rapidly quenched alloy ribbon to be as small as possible.

[0030] Also, in the manufacturing method of the present embodiment, it is desirable to select a soft magnetic rapidly quenched alloy ribbon, resin, curing temperature, etc. in accordance with the specified value of the above adhesive stress σ.

[0031] Hereinafter, the laminated magnetic material of the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a schematic perspective view for explaining an embodiment of the laminated magnetic material of the present embodiment. FIG. 1(a) is a schematic perspective view showing an embodiment of the laminated magnetic material and does not necessarily match the actual dimensions. Also, FIG. 1(a) shows an example in which the soft magnetic rapidly quenched alloy ribbon is three layers, but in the present embodiment, the number of layers is not limited.

[0032] The laminated magnetic material 11 of the present embodiment includes a plurality of soft magnetic rapidly quenched alloy ribbons 1 and resin layers 2 disposed between the plurality of soft magnetic rapidly quenched alloy ribbons 1. FIG. 1(b) is a schematic perspective view showing an embodiment of the soft magnetic rapidly quenched alloy ribbon 1, and there are two opposing main surfaces 1a, 1b.

[0033] FIG. 2 is a schematic perspective view showing a laminated magnetic material 12 in which a resin layer 2 is disposed between two soft magnetic rapid-quenching alloy ribbons 1. As described above, the resin layer 2 is disposed on at least one of the main surfaces 1a and 1b of the soft magnetic rapid-quenching alloy ribbon 1. The resin layer 2 may be disposed on each of the two main surfaces 1a and 1b of the soft magnetic rapid-quenching alloy ribbon 1. The resin layer 2 may be disposed over the entire main surfaces 1a and 1b, or may be provided in a predetermined pattern including a region where the resin layer 2 is disposed, such as in a stripe shape or a dot shape, and a region where the resin layer 2 is not disposed, on the main surfaces 1a and 1b.

[0034] Hereinafter, the measurement and evaluation techniques applied to the examples of the present embodiment will be described. (1. Adhesive stress σ) The adhesive stress σ [MPa] can be evaluated by the above-described (Equation 1). Hereinafter, the method for deriving each factor for calculating the adhesive stress σ will be described.

[0035] (1-1. Flexural modulus γ of the resin cured product) Hereinafter, a resin cured under predetermined conditions for use in a laminate will be referred to as a resin cured product. The flexural modulus γ [MPa] of the resin cured product uses the flexural modulus at room temperature (=23±5°C). The flexural modulus γ of the resin cured product is measured by a three-point bending test with reference to JIS K7171:2016. As the apparatus for the bending test, an autograph AGX-100kN manufactured by Shimadzu Corporation is prepared. The test piece is produced by pouring resin into a mold having a rectangular cross-section and a strip shape and curing the resin. The size at this time is set to thickness T×width W×length l =: 2 mm×25 mm×40 mm. The number of test pieces is three for each resin.

[0036] The distance L between the supports in the three-point bending test is 30 mm. The test speed is 1 mm / min, and the load F [N] applied to the sample continuously and the deflection D [mm] at that time are measured until the bending strain ε derived from the following (Equation 2) exceeds 0.0025.

[0037] From the measured load F and deflection D, bending stress τ and bending strain ε are calculated using the following (Equation 2) and (Equation 3), and a stress-strain curve is obtained. Linear regression by the least squares method is performed on the stress curve in the bending strain range of 0.0005 ≦ ε ≦ 0.0025 of the stress-strain curve, and the slope is taken as the bending elastic modulus γ. The measurement is repeated three times for each resin using different test pieces, and the average value is taken as the bending elastic modulus γ of the resin at room temperature. (Equation 2) ε = (6 × T / L 2 ) × D (Equation 3) τ = (3 × F × L) / (2 × W × T 2 )

[0038] As shown in (Equation 1), in order to reduce the adhesion stress σ, it is effective to have a low bending elastic modulus γ. In order to lower the bending elastic modulus γ, it is effective to use a resin with a low glass transition temperature Tg. The bending elastic modulus γ is preferably 2600 MPa or less, more preferably 1000 MPa or less, and even more preferably 100 MPa or less. In order to obtain these bending elastic moduli γ, the glass transition temperature Tg is preferably 110 °C or less, more preferably 70 °C or less, and even more preferably room temperature or less.

[0039] (1 - 2. Linear thermal expansion coefficient α of the resin cured product 1 ) The linear thermal expansion coefficient α of the resin cured product 1 [1 / °C] is measured using a thermomechanical analyzer (TMA) with reference to JIS K7197:1991. As a device that can raise the temperature of the test piece at a constant rate and measure in the compression mode in a certain atmosphere, the DIL402 thermomechanical analyzer manufactured by NETZSCH is used. This device has a space for inserting a jig with a sample set in a cylindrical furnace, and the linear thermal expansion coefficient α of the sample attached to this jig 1 can be measured. Also, in this device, a sample with a length of 15 mm is required, but it is difficult to form such a size with the resin to be measured. Therefore, a resin piece with a size of 4.2 mm square × 5 mm in length and an alumina spacer with a known linear thermal expansion coefficient of φ6 mm × 10 mm in length are connected in series to form a 15 mm sample, and this is used as the measurement object.

[0040] As the measurement conditions, the heating rate is about 1 °C / min, and the measurement temperature range is 35 °C to 55 °C. The average linear thermal expansion coefficient in the range of 40 °C to 50 °C during the heating process is calculated by the method described in JIS K7197:1991, and this average linear expansion coefficient is used as the linear thermal expansion coefficient α of the resin. 1 The measurement is repeated three times for different test pieces for each resin, and the average value is taken as the linear thermal expansion coefficient α of the resin. 1 This is used.

[0041] (1-3. Linear thermal shrinkage rate β during resin curing) The linear thermal shrinkage rate β [dimensionless] during resin curing is calculated from the specific gravity Sg of the uncured resin i and the specific gravity Sg of the cured resin f using the following approximate formula (Equation 4). (Equation 4) β ≒ (1 - (Sg i / Sg f )) / 3

[0042] (For Equation 4), the specific gravity Sg of the uncured resin i and the specific gravity Sg of the cured resin f are measured in accordance with the specific gravity cup method described in JIS K6833-1:2008 and the water displacement method described in JIS K7112:1999. In addition, for the uncured specific gravity in the case of a two-component mixed adhesive, it is calculated by the following method. If the two-component mixed adhesive is designated as Agent A and Agent B, the specific gravity Sg A of Agent A before curing and the specific gravity Sg B of Agent B before curing are measured using the specific gravity cup method described in JIS K6833-1:2008. Based on the recommended mixing mass ratio of the two-component mixed adhesive, the masses of Agent A and Agent B to be mixed (the mass M A of Agent A and the mass M B of Agent B) are determined and calculated according to the following (Equation 5). (Equation 5) Sg i = (M A + M B ) / (M A / Sg A + M B / Sg B )

[0043] (1-4. Thickness h of the resin in the laminated magnetic material 1 and thickness h of the soft magnetic rapidly solidified alloy ribbon in the laminated magnetic material 2 ) The thickness of the soft magnetic rapidly solidified alloy ribbon is h 2 and is evaluated by obtaining the thickness per sheet from the density derived by the water substitution method and multiplying by the number of laminations. The thickness of the resin in the laminated magnetic material is h 1 and is calculated by the weight M of the laminated magnetic material after adhesion lam , the weight M of only the magnetic material in the laminated magnetic material mag , the specific gravity Sg of the cured resin evaluated in (Equation 4) f and the coated area A of the resin using the following formula. (Equation 6) h 1 =(M lam -M mag ) / (Sg f ×A)

[0044] (2. Glass transition temperature Tg) The glass transition temperature Tg of the cured resin is measured by the heat flux differential scanning calorimetry method using a differential scanning calorimeter (DSC) with reference to JIS K7121:2012. As the measuring apparatus, DSC, 3500 Sirius manufactured by NETZSCH is prepared. An aluminum pan for DSC measurement containing about 10 mg of the cured resin sample is set in this apparatus, and measurement is performed under an argon atmosphere with a flow rate of 50 ml / min.

[0045] The temperature scanning is performed as follows. First, the temperature is raised from near room temperature to about 50 °C or more higher than the expected glass transition temperature Tg of the sample (up to 60 °C for those whose glass transition temperature is expected to be below room temperature) at a heating rate of 20 °C / min, and held at that temperature for 10 minutes. Next, the temperature is lowered to -140 °C at a cooling rate of 20 °C / min, and held at that temperature for 10 minutes. Subsequently, the temperature is raised to 220 °C at a heating rate of 20 °C / min. The DSC curve measured in this second heating process is used for the analysis of the glass transition temperature Tg.

[0046] The method for obtaining the glass transition temperature Tg is as follows. First, the temperature of the intersection of the straight line obtained by extending the baseline on the low-temperature side to the high-temperature side with respect to the stepwise change portion of the glass transition in the DSC curve and the tangent line drawn at the point where the gradient of the curve of the stepwise change portion of the glass transition becomes maximum is defined as the extrapolated glass transition start temperature. Next, the intersection of the straight line obtained by extending the baseline on the high-temperature side to the low-temperature side and the tangent line drawn at the point where the gradient of the curve of the stepwise change portion of the glass transition becomes maximum is defined as the extrapolated glass transition end temperature. The temperature midway between the extrapolated glass transition start temperature and the extrapolated glass transition end temperature is defined as the midpoint glass transition temperature, and the midpoint glass transition temperature is defined as the glass transition temperature Tg of the resin. In addition, when multiple glass transitions are observed in the measurement temperature range of -140 to 220 °C, the portion where the largest stepwise change of the glass transition occurs is analyzed as the glass transition temperature of the main component of the resin, and it is defined as the typical glass transition temperature Tg of the resin.

[0047] (3. Occupancy ratio) The occupancy ratio SF is the thickness h of the resin in the laminated magnetic material 1 and the thickness h of the soft magnetic rapidly quenched alloy ribbon in the laminated magnetic material 2 From these, the calculation is performed using the following formula. Here, when the occupancy ratio SF is expressed as a percentage (%), it is assumed that 100 is multiplied by the following formula. (Equation 7) SF = h 2 / (h 1 + h 2 )

[0048] (4. Peel strength at room temperature) The peel strength of the laminated magnetic material at room temperature refers to the peel strength evaluated by the T-peel test among the 180° peel test methods and is measured in accordance with JISK6854-3:1999. The apparatus used for the T-peel test is the Autograph AGX-100kN V manufactured by Shimadzu Corporation. A load cell with a capacity of 50 N is used.

[0049] Figure 3 is a diagram for explaining a test piece of the T-peel test used in the example of this embodiment. A two-layer laminated magnetic material with a minimum length of 200 mm × width of 25 ± 0.5 mm is fabricated, and one side (part B: length 50 mm) is peeled off to obtain a test piece. The number of test pieces is 5 for each resin.

[0050] The test is performed at room temperature (23 °C) by grasping the tip 25 mm of part B and pulling it in the direction of the arrow in the figure. The peeling speed is kept constant at 100 mm / min, and pulling continues until the entire adhesive part (part C: length 150 mm) is peeled off. The evaluation range of the measurement results is the range excluding the part peeled off at the start of peeling of part C (part E 1 : 25 mm) and the part peeled off at the end of peeling of part C (part E 2 : 25 mm). For each individual test piece, the average peeling force in this evaluation range is recorded. The measurement is repeated 5 times for different test pieces for each resin, and the average value of the average peeling strength of each test piece is taken as the peel strength [gf / mm] at room temperature of the laminated magnetic material using that resin.

[0051] (5. Peel strength at high temperature) The peel strength of the laminated magnetic material at 75 °C is measured by changing some of the measurement conditions from the above peel strength measurement at room temperature. As the apparatus for the T-peel test, Autograph AGX-100kN manufactured by Shimadzu Corporation is prepared. A load cell with a capacity of 50 N is used. Also, a thermostatic chamber TCE-N300 manufactured by Shimadzu Corporation is prepared.

[0052] A test piece is prepared by fabricating a two-layer laminated magnetic material with a minimum length of 200 mm × width of 25 ± 0.5 mm, and one side (part B: length 50 mm) is peeled off to obtain a test piece. The number of test pieces is 5 for each resin. The test is carried out by installing the gripping jig of the autograph and the test piece in an air atmosphere heated to 75 °C in the above thermostatic chamber and measuring. The peeling speed is kept at a constant speed of 100 mm / min, and pulling continues until the adhesive part (part C: length 72.5 mm) is peeled off. The evaluation range of the measurement results is the part peeled off at the start of peeling of part C (part E 1Evaluate within the range excluding the part (20 mm). Record the average peel force in this evaluation range for each test piece. The measurement is repeated 5 times for different test pieces for each resin, and the average value of the average peel strength of each test piece is taken as the peel strength [gf / mm] at room temperature of the laminated magnetic material using that resin.

[0053] (6. Magnetic properties B80 and P CM14 / 50 ) Two types of evaluation values are derived for the magnetic properties, namely the evaluation value as a laminated magnetic material and the evaluation value as the soft magnetic rapidly quenched alloy ribbon part constituting the laminated magnetic material. When deriving as the soft magnetic rapidly quenched alloy ribbon part, the cross-sectional area and mass of the soft magnetic rapidly quenched alloy ribbon part are used as the criteria. Each magnetic property was measured with reference to JISC2556:2015. The measurement principle was measured using the excitation current method described in JISC2556:2015. As the measurement device, an alternating magnetic property measurement device, BH loop analyzer SY8218 manufactured by Iwasaki Telecommunications Co., Ltd., was used, and as the amplifier, a power amplifier SY-5001 manufactured by PMK was used. Also, as a measurement jig, a measurement frame was fabricated with reference to JISC2556:2015 and used.

[0054] The measurement frame is composed of an MnZn ferrite yoke, a resin bobbin, and a polyurethane-coated copper wire. The MnZn ferrite yoke is U-shaped, and two yokes of the same shape are used. During measurement, the sample was sandwiched from above and below using two MnZn ferrite yokes for measurement. By sandwiching the ribbon with the MnZn ferrite yoke, the flow of magnetic flux can be made into a closed magnetic circuit, preventing the generation of a demagnetizing field in the ribbon, and ensuring the uniformity of the magnetic field distribution applied to the test piece and the magnetic flux distribution within the test piece.

[0055] A primary winding (excitation coil) (wire diameter 0.5 mm) and a secondary winding (B coil) (wire diameter 0.5 mm) were each wound 57 and 100 turns around a resin bobbin with a polyurethane-coated copper wire. A sample was inserted between the bobbins, and a magnetic field was applied to a ribbon with a bobbin length of 36.2 mm. Also, the background generated due to the air gap between the MnZn ferrite yoke and the coil and the magnetic material was corrected by connecting a compensation coil between the jig and the BH loop analyzer and adjusting the number of turns of the compensation coil so that the output without a sample became zero when a magnetic field of 8000 A / m was applied.

[0056] An example of the core for a transformer according to this embodiment will be described. FIG. 4 is a perspective view showing an embodiment of the core for a transformer according to this embodiment. Four laminated magnetic materials 11 are arranged such that the end faces perpendicular to the plurality of lamination directions are butted against each other to form a rectangular core for a transformer as a whole. However, the shape of the core for a transformer is not limited to this embodiment.

Example

[0057] As an Fe-based soft magnetic rapidly quenched alloy ribbon, a ribbon of 2605HB1M (registered trademark), which is an amorphous alloy manufactured by Proterial Co., Ltd. by the single-roll method with a length of 120 mm, a width of 25 mm ± 0.5 mm, and a thickness of 25 μm, was prepared. Before bonding, a tension of 40 MPa was applied in the longitudinal direction of the ribbon, and tension annealing was performed at 450°C to impart an induced magnetic anisotropy such that this direction became the easy magnetization direction. As a result, B80 could be adjusted to 1.55 T. Also, the linear thermal expansion coefficient α of the ribbon alone before this bonding 2 was 4.3×10 -6 [1 / °C], and it was confirmed that P CM14 / 50 was 0.114 W / kg.

[0058] Next, two pieces of the above-mentioned soft magnetic rapid-quenching alloy ribbons were bonded using nine types of resins having various adhesive stresses (for convenience, these resins are referred to as a, b, c, d, e, f, g, h, and i), and Examples 1 to 6 and Comparative Examples 1 to 4 of the laminated magnetic materials were produced. The bonding was applied to the entire surface of the soft magnetic rapid-quenching alloy ribbon using the flexographic printing method, and the other soft magnetic rapid-quenching alloy ribbon was overlaid and crimped with a roller. After crimping, it was heated at each curing temperature, or for those cured at room temperature, it was left at room temperature and cured sufficiently. Then, for each laminate, B80 and P CM14 / 50 were measured.

[0059] The type of resin used in each sample and each factor related to bonding are shown in Tables 1 to 2. Note that the linear thermal shrinkage rate δ [%] in Table 2 is the linear thermal expansion coefficient α of the resin cured product 1 [10 -6 / °C], the linear thermal expansion rate α of the soft magnetic rapid-quenching alloy ribbon 2 (4.3×10 -6 / °C), the curing temperature Ta [°C] of the resin, and room temperature RT (23°C), and is obtained by multiplying the value obtained using the following (Equation 8) by 100. (Equation 8) is a part of the terms of the formula for adhesive stress σ (Equation 1). (Equation 8) δ = (α 1 −α 2 ) × (Ta − RT)

[0060]

Table 1

[0061]

Table 2

[0062] Based on each factor shown in the above table, the adhesive stress σ was derived based on (Equation 1), and the magnetic properties of the samples were measured. The results are shown in Table 3. Note that in Table 3, the magnetic properties evaluated for the soft magnetic rapid-quenching alloy ribbon part constituting the laminated magnetic material are also shown.

[0063]

Table 3

[0064] B80 and P in the entire laminated magnetic material shown in Table 3 CM14 / 50 will be described. In Examples 1 to 6, a resin having a glass transition temperature Tg of the resin cured product of 110°C or lower and a flexural modulus γ of the resin cured product of 2600 MPa or lower was used. As a result, as can be seen from Tables 1 to 3, the adhesive stress σ was 2.5 MPa or lower, the B80 was as high as 1.25 T or more compared to the comparative example, and P CM14 / 50 was suppressed to 0.26 W / kg or lower. This is an appropriate magnetic property as a core for a distribution transformer using a commercial frequency band.

[0065] Furthermore, in Examples 1 to 3, a resin having a glass transition temperature Tg of the resin cured product of 50°C or lower and a flexural modulus γ of the resin cured product of 1000 MPa or lower was used. As a result, as can be seen from Tables 1 to 3, the adhesive stress σ was 0.5 MPa or lower, the B80 was very high at 1.4 T or more, and P CM14 / 50 was very much suppressed to 0.18 W / kg or lower. This is an even more appropriate magnetic property as a core for a distribution transformer using a commercial frequency band.

[0066] Using the peel strength measurement method at room temperature and high temperature of 75°C described above, the peel strength of each sample of Examples 1 to 6 was measured. Further, as Comparative Example 5, a two-layer laminate similar to the example was prepared using a polyester resin (for convenience, referred to as resin k), which is a hot-melt type thermoplastic resin, and the peel strength was similarly measured. The results are shown in Table 4.

[0067]

Table 4

[0068] The peel strengths of Examples 1 to 6 were 0.5 gf / mm or more at room temperature and 0.8 gf / mm or more under high temperature of 75°C. A peel strength of 0.5 gf / mm or more is a strength at which problems such as crumbling during handling do not occur, and a peel strength of 0.8 gf / mm or more is a more preferable strength. Further, in Examples 1 to 6, the peel strength does not significantly decrease with an increase in temperature as in Comparative Example 5 using a polyester resin, and the ratio of the peel strength at 75°C to the peel strength at room temperature is 0.4 or more, indicating that it can withstand practical use.

[0069] From the above, according to the present embodiment, it is possible to provide an excellent laminated magnetic material having excellent heat resistance, maintaining a high magnetic flux density and having little iron loss, a core for a transformer, and a method for manufacturing a laminated magnetic material.

[0070] As described above, the present invention has been described using the above embodiments, but the technical scope of the present invention is not limited to the above embodiments.

Explanation of reference numerals

[0071] 1: Soft magnetic rapidly quenched alloy ribbon 1a, 1b: Main surfaces of the soft magnetic rapidly quenched alloy ribbon 2: Resin layer 11, 12: Laminated magnetic material B: Peeling portion C: Adhesive portion E 1 : Peeling start portion E 2 : Peeling end portion

Claims

1. A laminated magnetic material in which Fe-based soft magnetic quenched alloy ribbons are interlayer-bonded with at least one resin selected from the group consisting of a thermosetting or room temperature curing epoxy resin, an epoxy-modified silicone resin, and an acrylic resin, The resin has a glass transition temperature of 110° C. or less as measured by a differential scanning calorimeter; A laminated magnetic material characterized in that the peel strength of the laminated magnetic material is 0.5 gf / mm or more at room temperature and 0.8 gf / mm or more at a high temperature of 75°C in a 180° peel test method, and the magnetic flux density B80 when a magnetic field of 80 A / m is applied in the longitudinal direction is 1.25 T or more.

2. When the laminated magnetic material is evaluated by the soft magnetic quenched alloy ribbon portion constituting the laminated magnetic material, The magnetic flux density B80 in the longitudinal direction when the magnetic field is 80 A / m is 1.4 T or more. Iron loss P at a frequency of 50 Hz and a maximum magnetic flux density of 1.4 T ＣＭ１４／５０ is 0.26 W / kg or less, 2. The laminated magnetic material according to claim 1,

3. The Fe-based soft magnetic quenched alloy ribbon has a thickness of 10 μm or more and 50 μm or less.

2. The laminated magnetic material according to claim 1.

4. The thickness of the resin in the laminated magnetic material is h １ [μm], the thickness of the soft magnetic quenched alloy ribbon in the laminated magnetic material is h ２ [μm], the bending modulus of the resin when cured at room temperature is γ [MPa], the linear thermal expansion coefficient of the resin evaluated at 40 to 50 ° C. is α １ [1 / °C], the linear thermal expansion coefficient of the soft magnetic quenched alloy ribbon is α ２ [1 / °C], the curing temperature applied to the resin is Ta [°C], room temperature is RT [°C], and the linear thermal shrinkage rate of the resin when cured is β, the adhesive stress σ [MPa] expressed by the following formula is 2.5 MPa or less. σ=M １ / / ２ ×γ×{(a １ -a ２ )×(Ta-RTT)+β]

5. 5. The laminated magnetic material according to claim 4, wherein the adhesive stress σ is 0.4 MPa or less.

6. A transformer core comprising the laminated magnetic material according to any one of claims 1 to 5.

7. A method for producing a laminated magnetic material in which Fe-based soft magnetic quenched alloy ribbons are interlayer-bonded with at least one resin selected from the group consisting of a thermosetting or room temperature curing epoxy resin, an epoxy-modified silicone resin, and an acrylic resin, comprising the steps of: A first step of adjusting the magnetic flux density B80 of the soft magnetic quenched alloy ribbon to 1.4 T or more when a magnetic field of 80 A / m is applied in a longitudinal direction; a second step of applying the resin, the glass transition temperature of which is 110° C. or lower as measured by a differential scanning calorimeter, to one or both sides of the soft magnetic quenched alloy ribbon; a third step of stacking the soft magnetic quenched alloy ribbons that have been subjected to the second step and hardening the resin; Due to a thickness of the resin in the laminated magnetic material is h 1 [μm], a thickness of the soft magnetic quenched alloy ribbon in the laminated magnetic material is h 2 [μm], a flexural modulus of the resin when cured at room temperature is γ [MPa], a linear thermal expansion coefficient of the resin evaluated at 40 to 50° C. is α 1 [1 / ° C.], a linear thermal expansion coefficient of the soft magnetic quenched alloy ribbon is α 2 [1 / ° C.], a curing temperature applied to the resin is Ta [° C.], room temperature is RT [° C.], and a linear thermal contraction coefficient of the resin when cured is β, an adhesive stress σ [MPa] represented by the following formula is within a range of 2.5 MPa or less, σ=h 1 / h 2 ×γ×{(α 1 −α 2 )×(Ta−RT)+β} The peel strength of the laminated magnetic material in a 180° peel test method is 0.5 gf / mm or more at room temperature and 0.8 gf / mm or more at a high temperature of 75°C, and the magnetic flux density B80 when a magnetic field of 80 A / m is applied in the longitudinal direction is 1.25 T or more.

2. A method for producing a laminated magnetic material comprising the steps of:

8. 8. The method for producing a laminated magnetic material according to claim 7, wherein the step of adjusting the magnetic flux density B80 to 1.4 T or more is performed by tension annealing.

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