WO2023120730A1

WO2023120730A1 - Laminated magnetic material, transformer core, and method for producing laminated magnetic material

Info

Publication number: WO2023120730A1
Application number: PCT/JP2022/047785
Authority: WO
Inventors: 石川湧己; 野口伸; 相牟田京平
Original assignee: 日立金属株式会社
Priority date: 2021-12-24
Filing date: 2022-12-23
Publication date: 2023-06-29

Abstract

The present invention provides: a laminated magnetic material which is excellent in terms of preventing a reduction in heat resistance and magnetic flux density and suppressing an increase in iron loss; and a method for producing a laminated magnetic material.　Provided is a laminated magnetic material in which laminated quenched alloy thin ribbons are bonded in layers with a resin that is heat curable or curable at normal temperature and that has a glass transition temperature of not more than 100°C, said laminated magnetic material being characterized in that the peeling strength of the laminated magnetic material at room temperature is not less than 1.0 gf/mm, and the magnetic flux density B80 of the entirety of the laminated magnetic material at an applied magnetic field of 80 A/m is not less than 1.25 T.

Description

LAMINATED MAGNETIC MATERIAL, TRANSFORMER CORE, AND METHOD FOR MANUFACTURING LAMINATED MAGNETIC MATERIAL

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

Amidst the global trend to reduce _CO2 emissions, there is a demand for higher efficiency power transformers. Grain-oriented electrical steel sheets have been used for the magnetic cores of power transformers. Instead, amorphous alloys, which have a low loss characteristic of about 1/3 to 1/5 that of electrical steel sheets, are being applied to cores for transformers. Expected. Electromagnetic steel sheets have a thickness of about 0.20 to 0.35 mm, whereas amorphous alloys require ultra-quenching during their production, and are supplied in strips having a thickness of about 25 μm, for example. Therefore, when a core of the same size as the magnetic steel sheet is made of an amorphous alloy, there is a problem that the core manufacturing process is overloaded, for example, the number of lamination times is required to be 10 times or more. In order to solve this problem, for example, as disclosed in Patent Document 1, studies have been conducted on bonding and laminating a plurality of amorphous alloy ribbons into a plate shape so that it can be handled in the same manner as an electromagnetic steel sheet.
However, even in this case, there is a problem that the magnetic properties of the amorphous alloy ribbon deteriorate due to adhesive stress generated between the resin (adhesive) and the amorphous alloy ribbon. Therefore, as disclosed in Patent Document 2, an attempt is made to reduce the load on the amorphous alloy ribbon and suppress the deterioration of the magnetic properties by using a soft resin (adhesive) such as a polyester resin having a durometer hardness of D60 or less. has been done. Here, durometer hardness is the hardness of a sample measured with a durometer (rubber hardness tester).

JP-A-2002-151316 WO2019/087932

However, a core for a transformer inevitably rises in temperature during use, and a thermoplastic resin such as the hot-melt polyester resin disclosed in Patent Document 2 cannot be said to have sufficient heat resistance and long-term reliability. Therefore, a new technique for preventing deterioration of magnetic properties has been sought.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a laminated magnetic material, a core for a transformer, and a method for manufacturing the laminated magnetic material, which are advantageous in ensuring heat resistance and reliability and maintain excellent magnetic properties. .

The laminated magnetic material of the present invention is a laminated magnetic material in which the laminated quenched alloy ribbons are thermosetting or room temperature curable and are interlayer-bonded with a resin having a glass transition temperature of 100° C. or less. The peel strength at room temperature is 1.0 gf/mm or more, and the magnetic flux density B80 of the entire laminated magnetic material is 1.25 T or more at an applied magnetic field of 80 A/m.

In addition, the quenched alloy ribbons bonded between layers with the resin have a magnetic flux density B80 of 1.4 T or more at an applied magnetic field of 80 A / m, and an iron loss Pcm of 0.26 W at a frequency of 50 Hz and a maximum magnetic flux density of 1.4 T. /kg or less.

In the present invention, the magnetic material has an elastic modulus of the resin at room temperature γ [MPa], a linear expansion coefficient of the resin below the glass transition temperature α1 [1/K], and a curing temperature of the resin Ta [ K], β is the linear shrinkage rate of the resin when cured, h1 [μm] is the resin thickness of the resin, h2 [μm] is the thickness of the quenched alloy ribbon, and α2 is the linear expansion coefficient of the quenched alloy ribbon. [1/K] and room temperature as RT, the adhesive stress σ [MPa] shown by the following formula is preferably 3 MPa or less.
σ = h1 / h2 × γ × {(α1-α2) × (Ta-RT) + β}
In the present invention, the adhesive stress σ is preferably 0.6 MPa or less.

The transformer core of the present invention preferably has the laminated magnetic material.

In the method for producing a laminated magnetic material of the present invention, the laminated quenched alloy ribbons are thermosetting or room temperature curable, and the laminated magnetic material is laminated with a resin having a glass transition temperature of 100° C. or less. A method for manufacturing a material, comprising the steps of: applying the resin to one or both sides of the quenched alloy ribbon; and laminating the quenched alloy ribbon and curing the resin.
characterized by
In the present invention, the resin is preferably at least one of epoxy resin, epoxy-modified silicone resin and acrylic resin.

According to the present invention, it is possible to provide an excellent laminated magnetic material for a transformer that has excellent heat resistance, is advantageous for ensuring reliability, maintains a high magnetic flux density, and has little iron loss.

1 is a schematic perspective view showing an embodiment of the laminated magnetic material of the present invention; FIG. 1 is a schematic perspective view showing an embodiment of the laminated magnetic material of the present invention in which a resin layer 2 is arranged between two quenched alloy ribbons 1. FIG. It is a schematic diagram of a test piece for a peel test. 1 is a schematic diagram of a peel test measuring device; FIG. 1 is a schematic perspective view showing an embodiment of a transformer core of the invention; FIG.

In forming a laminated magnetic material for a transformer, the present inventor clarified the relationship between the physical properties and adhesion conditions of the resin and the adhesive stress σ determined by the various physical properties of the resin. The present invention has been completed by discovering a laminated magnetic material for a transformer which maintains the magnetic properties of the transformer. A detailed description will be given below.
First, the present inventors made a detailed study of a magnetic material provided with a resin (adhesive) as disclosed in Patent Document 1. When trying to manufacture a laminated magnetic material by applying a resin (adhesive) between amorphous alloy ribbon layers, the volume decreases when the resin (adhesive) hardens, and when it is heated and adhered, Since there is a difference in thermal expansion coefficient between the amorphous alloy ribbon and the adhesive, the resin (adhesive) applies adhesive stress mainly in the in-plane direction to the amorphous alloy ribbon.
Here, when considering a plurality of soft magnetic amorphous alloy ribbons and a resin layer made of a resin (adhesive) disposed between the soft magnetic amorphous alloy ribbons, the elastic modulus of the resin at room temperature is γ [MPa], α1 [1/K] is the linear expansion coefficient of the resin at room temperature, Ta [K] is the curing temperature of the resin, β is the linear shrinkage rate of the resin when cured, h1 [μm] is the resin thickness of the resin, and amorphous When the thickness of the alloy ribbon is h2 [μm], the linear expansion coefficient of the amorphous alloy ribbon is α2 [1/K], and the room temperature is RT, the adhesive stress σ [MPa] shown by the following formula is It is represented by a formula. In addition, [] represents a unit. Here, RT at room temperature is assumed to be 296 [K].

Since the amorphous alloy ribbon has a large magnetostriction, the magnetic domain structure of the amorphous alloy ribbon is disturbed by the adhesive stress, and the magnetic properties of the amorphous alloy ribbon are changed. In particular, when amorphous alloy ribbons are laminated to form a laminated magnetic material, and a laminated core made of these laminated magnetic materials is used as a core for a power transformer in the commercial frequency band (50 Hz, 60 Hz), iron loss increases and a predetermined magnetic field A phenomenon occurs in which the magnetic flux density decreases when is applied. An increase in the iron loss of the core leads to a decrease in efficiency of the transformer, and a decrease in magnetic flux density when a predetermined magnetic field is applied causes a problem of increased noise generated when the transformer is excited. Therefore, when using an amorphous alloy ribbon as a core for a transformer, it is important to control the adhesive stress generated in the amorphous alloy ribbon to be as small as possible.
Also, by grasping the allowable limit of the stress, useful knowledge can be obtained in selecting usable resins. This adhesive stress varies depending on the type of resin forming the adhesive. In other words, it was found that the magnetic properties, particularly the iron loss _PCM and the magnetic flux density B80, could vary greatly depending on the type of resin layer used for lamination. The iron loss P _CM (hereinafter referred to as P _CM14/50 ) is the iron loss [W/kg] at a frequency of 50 Hz and the maximum magnetic flux density of 1.4 T, and the magnetic flux density B80 (hereinafter referred to as B80) is Represents the magnetic flux density [T] when magnetized with an applied magnetic field of 80 A/m. Based on this finding, the present inventor has conceived of a novel magnetic material.

That is, the present invention provides a laminated magnetic material in which laminated quenched alloy ribbons are thermosetting or room temperature curable and are interlayer-bonded with a resin having a glass transition temperature of 100° C. or less,
The laminated magnetic material has a peel strength of 1.0 gf/mm or more at room temperature and a magnetic flux density B80 of 1.25 T or more at an applied magnetic field of 80 A/m for the entire laminated magnetic material.

The resins of the present invention should be thermosetting or cold setting. Thermosetting or normal-temperature-setting resins are relatively low-molecular-weight liquid compounds before reaction. It is a resin that initiates a polymerization reaction when it is blocked and comes into contact with an active metal, and when it is polymerized into a polymer compound, it hardens and becomes a solid. Thermosetting or normal-temperature-setting resins have higher heat resistance than hot-melt thermoplastic resins, and their adhesive strength is less likely to decrease even at high temperatures.
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a laminated magnetic material, a transformer core, and a method for manufacturing a laminated magnetic material according to the present invention will be described in detail below with reference to the drawings.

First, an embodiment of the laminated magnetic material of the present invention will be described. FIG. 1(a) is a schematic perspective view showing one embodiment of the laminated magnetic material. A laminated magnetic material 11 of this embodiment includes a plurality of quenched alloy ribbons 1 and a resin layer 2 disposed between the plurality of quenched alloy ribbons 1 . In addition, the form in a figure is shown typically, and does not necessarily correspond with an actual dimension. FIG. 1(b) is a schematic perspective view showing one embodiment of the quenched alloy ribbon 1, which has two main surfaces 1a and 1b facing each other.
Here, the laminated magnetic material 11 preferably has a B80 of 1.25 T or more.

[Quenched alloy ribbon]
The material of the quenched alloy ribbon 1, which constitutes the laminated magnetic material 11 of the present embodiment, is not particularly limited. Fe-based amorphous alloy ribbon can be used. Here, "2605HB1M" is a registered trademark of Hitachi Metals, Ltd. In particular, in the case of the Fe-based amorphous alloy ribbon, the composition is such that when the total amount of Fe, Si, and B is 100 atomic %, Si is 0 atomic % or more and 10 atomic % or less, and B is 10 atomic %. More than 20 atomic % or less is preferable.

The width of the quenched alloy ribbon 1 is not particularly limited, but can be, for example, 100 mm or more. If the width of the ribbon is 100 mm or more, a practical transformer can be favorably produced. More preferably, the width of the ribbon is 125 mm or more. On the other hand, the upper limit of the width of the ribbon is not particularly limited. brittleness, and the magnetic flux density B80 may decrease. More preferably, the width of the ribbon is 275 mm or less.

The thickness of the quenched alloy ribbon 1 is preferably 10 µm or more and 50 µm or less. If the thickness is less than 10 μm, the mechanical strength of the quenched alloy ribbon 1 tends to be insufficient. More preferably, the thickness is 15 μm or more, and more preferably 20 μm or more. On the other hand, when the thickness of the ribbon exceeds 50 μm, it tends to be difficult to stably obtain an amorphous phase. The thickness is more preferably 35 μm or less, and even more preferably 30 μm or less.

The quenched alloy ribbon 1 has no anisotropy derived from the crystal structure and does not have crystal grain boundaries that impede movement of domain walls, so it has excellent soft magnetic properties such as high magnetic permeability and low loss while maintaining high magnetic flux density. have. Further, the quenched alloy ribbon 1 alone preferably has a B80 of 1.48 T or more.

The quenched alloy ribbon 1 can be produced by various known methods. For example, by preparing a molten alloy having the composition described above and discharging the molten alloy onto the surface of the chill roll, a film of the molten alloy is formed on the surface of the chill roll, and the amorphous alloy ribbon 1 formed on the surface is It is obtained by peeling from the surface of the cooling roll by blowing a peeling gas and winding it into a roll shape with a take-up roll.

The quenched alloy ribbon 1 is effective as a transformer ribbon after heat treatment so that the direction of easy magnetization is in the longitudinal direction of the ribbon. As a method for obtaining such a quenched alloy ribbon, in the case of heat treatment, for example, a method of heat treatment while being stretched (tension annealing), or a method of heat treatment while a magnetic field is applied in the longitudinal direction of the ribbon, A method of heat-treating the ribbon while applying a magnetic field in the longitudinal direction of the ribbon while being stretched is preferable. The resin layer 2 is formed on the quenched alloy ribbon 1 subjected to such a heat treatment, and another quenched alloy ribbon 1 is joined to form the laminated magnetic material 11 .

[Resin layer]
The resin layer 2 of the laminated magnetic material 11 of this embodiment is arranged on at least one of the two principal surfaces 1a and 1b of the quenched alloy ribbon 1 . FIG. 2 is a schematic perspective view showing a laminated magnetic material 12 in which a resin layer 2 is arranged between two quenched alloy ribbons 1. As shown in FIG. Here, the resin constituting the resin layer 2 has an elastic modulus of the resin at room temperature γ [MPa], a linear expansion coefficient of the resin at room temperature α1 [1/K], a curing temperature of the resin Ta [K], and the resin β is the linear shrinkage rate at the time of curing, h1 [μm] is the resin thickness of the resin, h2 [μm] is the thickness of the quenched alloy ribbon, and α2 [1 / K] is the linear expansion coefficient of the quenched alloy ribbon. , room temperature is RT, the adhesive stress σ [MPa] calculated by the above equation 1 is preferably 3 MPa or less, and is preferably formed using a thermosetting or room temperature curable resin.

Here, the following physical property values are used for the physical properties of the resin used for calculating the adhesive stress.
The bending elastic modulus at room temperature (=296 K) is used as the elastic modulus γ [MPa] of the resin. The flexural modulus was measured by pouring resin into a strip-shaped mold and curing the resin. mm] (=40 mm), a three-point bending test is performed using a measuring device conforming to the JISK7171 method. The distance L between the fulcrums is 30 mm when the bending elastic modulus of the resin exceeds 700 MPa, 14 mm when the bending elastic modulus is 70 MPa or more and 700 MPa or less, and 8 mm when the bending elastic modulus is less than 70 MPa. do. The test speed was set to 0.48 mm/min, and the load F [N] continuously applied to the sample until the bending strain ε derived from Equation 2 below exceeded 0.0025, and the deflection D [mm] at that time were measured. do. Bending stress τ and bending strain ε are calculated from the measured load and deflection using the following formulas (Equations 2 and 3) to obtain a stress-strain curve. The stress curve in the bending strain section 0.0005≦ε≦0.0025 of the stress-strain curve is linearly regressed by the method of least squares, and the slope thereof is defined as the bending elastic modulus [MPa].

The linear expansion coefficient α1 [1/K] of the resin at room temperature is measured using a thermomechanical analyzer (TMA). The linear shrinkage rate β of the cured resin is calculated using the following formula from the specific gravity of the uncured resin and the specific gravity of the cured resin.

The specific gravity of the uncured resin and the specific gravity of the cured resin are measured according to the JISK6833 specific gravity cup method and the JISK7122 water substitution method.
In addition, the uncured specific gravity in the case of a two-liquid mixing type adhesive is calculated by the following method. Assuming that two-liquid mixed adhesives are A agent and B agent, the respective specific gravities of A agent and B agent are measured using the JISK6833 specific gravity cup method. Based on the recommended mixing mass ratio of the two-liquid mixing type adhesive, the masses of the components A and B to be mixed are determined and calculated according to the following formula.

In the present invention, the adhesive stress σ is preferably 3 MPa or less. The reason for this is that the magnetic domain structure of the quenched alloy ribbon changes due to the adhesive stress acting on the quenched alloy ribbon from the resin, but if the adhesive stress is 3 MPa or less, the influence on the magnetic domain structure can be reduced. This is because it is possible to prevent deterioration of the magnetic properties of the quenched alloy ribbon.
When the adhesive stress σ of the resin is 3 MPa or less, the laminated magnetic material for a transformer has good magnetic properties such that the B80 of the entire laminated magnetic material is 1.25 T or more and the _PCM14/50 is 0.26 W/kg or less. wood is obtained. Furthermore, the adhesive stress σ is more preferably 0.6 MPa or less. By using a thermosetting or room-temperature-setting resin whose adhesive stress is within this range, the B80 of the entire laminated magnetic material is 1.39 T or more, and the _PCM14/50 is 0.16 W/kg or less. A laminated magnetic material for a transformer having magnetic properties is obtained.

In general, thermosetting or normal-temperature-setting resins have higher heat resistance than hot-melt thermoplastic resins, and their adhesive strength is less likely to decrease at high temperatures. Transformer cores inevitably rise in temperature during use, so hot-melt thermoplastic resins had concerns about their heat resistance and long-term reliability. For this reason, it is desirable to use a thermosetting or room-temperature-setting resin with excellent heat resistance. Moreover, it is desirable that the laminated magnetic material for transformers has a high space factor of 90% or more. Hot-melt thermoplastic resins must be dissolved in an organic solvent for coating such thin films, and the use of organic solvents raises concerns about the effects on the human body and the environment. Also, in the production process, it is necessary to install a local exhaust system, etc., and take anti-explosion measures, etc., in order to prevent contamination and diffusion of the solvent vapor into the working environment. On the other hand, a thermosetting or normal-temperature-setting resin is a liquid compound with a relatively low molecular weight before curing, and therefore has a low viscosity and can be applied thinly without using a solvent such as an organic solvent. Therefore, there is little influence on the human body and the environment, and there is an advantage that the production process can be simplified.

The thermosetting or room-temperature-setting resin used in this embodiment may be of any composition. Typical thermosetting or room temperature setting resins include epoxy resins, acrylic resins, modified silicone resins, silicone resins, unsaturated polyester resins, vinyl ester resins, and the like. The resin layer of the laminated magnetic material of the present invention is a resin composition containing at least one of these thermosetting or room temperature setting resins as a component. Other components may include curing agents, and if necessary, other resins, curing accelerators, fillers, solvents, plasticizers, and the like. The thermosetting or normal temperature setting resin is preferably at least one of epoxy resin, epoxy-modified silicone resin and acrylic resin.

Epoxy resins are the most widely used thermosetting resins or room temperature curing resins, and are particularly preferable because they come in many types and are highly practical, including from an economic standpoint. The epoxy resin used in this embodiment is not particularly limited, but known monofunctional epoxy resins, polyfunctional epoxy resins, and the like can be used. Examples thereof include modified epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, aliphatic type epoxy resin, glycidylamine type epoxy resin, urethane modified epoxy resin, and rubber modified epoxy resin. These epoxy resins may be used alone or in combination of two or more. The content of the epoxy resin in the resin layer is preferably at least 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more, in order to develop high adhesive strength peculiar to epoxy resins. On the other hand, if the content is too large, the elastic modulus increases and the adhesive stress applied to the soft magnetic amorphous alloy ribbon 1 increases.

There are many types of acrylic resins, and in addition to being thermosetting resins or room temperature curing resins that are highly practical from an economic standpoint, the curing speed is fast, so the bonding process can be shortened. Among the curing types, even if the two liquids are not thoroughly mixed, the reaction can start and cure when the two liquids come into contact (honeymoon adhesion). Since there are many types of room-temperature curing methods such as adhesion and photocurable adhesion, it is preferable because the adhesion process can be easily optimized. The acrylic resin used in the present invention is thermosetting or room temperature setting. Room temperature curing acrylic resins include second generation acrylic resins (SGA). SGA is a resin that is hardened by graft polymerization of an elastomer and an acrylic monomer. Although it is thermoplastic, it has high heat resistance and does not easily lose adhesive strength at high temperatures. Examples of acrylic resin components include polyacrylic acid and its copolymer, polyacrylic acid ester and its copolymer, polymethacrylic acid and its copolymer, polymethacrylic acid ester and its copolymer, urethane-acrylic Examples include acid copolymers, styrene-acrylic acid copolymers, and the like. These acrylic resins may be used alone or in combination of two or more. The content of the acrylic resin in the resin layer is preferably at least 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more, in order to develop high adhesive strength peculiar to acrylic resins.

Epoxy-modified silicone resin is preferable because it has an extremely low elastic modulus and can greatly reduce adhesive stress. The type of epoxy-modified silicone resin can be either one in which some of the functional groups of the modified silicone resin are substituted with epoxy groups, or one in which the epoxy resin and the modified silicone are incompatible and phase-separated to form a sea-island structure. good. The content of the epoxy-modified silicone resin in the epoxy-modified silicone resin composition is preferably at least 10% by mass or more.

From the viewpoint of maintaining excellent magnetic properties of the laminated magnetic material, it is preferable to increase the space factor as much as possible and have a space factor of 90% or more. The thickness of the resin layer 2 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 2 is too thin, sufficient adhesive strength cannot be exhibited, so the thickness is preferably 1 μm or more, more preferably 1.5 μm or more.

(Space factor calculation method)
The space factor is calculated by the following formula.
Here, when displaying the space factor in percentage (%), the following formula is multiplied by 100.

The resin layer 2 is preferably adhered to at least one of the main surfaces 1a and 1b of the quenched alloy ribbon 1 so as not to be easily peeled off. The resin layers 2 may be arranged on the two main surfaces 1a and 1b of the quenched alloy ribbon 1, respectively. The resin layer 2 may be arranged on the entire main surfaces 1a, 1b, or may be arranged on the main surfaces 1a, 1b in stripes, dots, or the like, where the resin layer 2 is arranged, and the resin layer 2 is arranged. It may be provided in a predetermined pattern including a region that does not

(Laminate magnetic material for peel strength evaluation)
FIG. 3 shows a schematic diagram of the laminated magnetic material 12 (laminated magnetic material for peel strength evaluation) used for the peel strength test. As shown in FIG. 3, the laminated magnetic material 12 is a laminated magnetic material in which a portion of one surface of the quenched alloy ribbon 1a and a portion of one surface of the quenched alloy ribbon 1b are adhered together. In other words, the laminated magnetic material is a laminated magnetic material that is not bonded (bonded) at one end in the longitudinal direction. The width of the laminated magnetic material is 25 mm, and the length of the bonded portion is 100 mm.

(Peel strength measurement method)
The peel strength of the laminated magnetic material is the force required to separate the laminated quenched alloy ribbons 1a and 1b, that is, the peel strength or holding force. Methods for measuring peel strength include, for example, the 90° or 180° peel test method (K6854: 1999).
As a specific example of the 180° peel test method, the peel strength can be measured using a peel strength measuring device 3 as shown in FIG. First, the other surface (the surface not coated with the resin) of the quenched alloy ribbon constituting the laminated magnetic material 12, for example, the other surface of the quenched alloy ribbon 1a, is attached to the metal base 3d with a double-faced tape 3e. fixed. Next, one end of the laminated magnetic material 12 that is not attached is gripped by a clip 3a, and the clip 3a is pulled at a constant speed by a force gauge 3b fixed via a linear guide 3c, and the load at that time is measured. Thus, the peel strength of the laminated magnetic material can be measured. Here, in this embodiment, the pulling speed was set to 90 mm/min.
For each test piece, load measurement is performed over a peel length of at least 40 mm excluding the first 25 mm, and the maximum load is taken as the peel strength [gf/mm] of the laminated magnetic material.

In the method for producing a laminated magnetic material according to the present embodiment, the laminated quenched alloy ribbons are thermosetting or room temperature curable, and are laminated with a resin having a glass transition temperature of 100° C. or less. A method for manufacturing a magnetic material, comprising the steps of: applying the resin to one or both sides of the quenched alloy ribbon; and laminating the quenched alloy ribbon and curing the resin.
Here, the resin in the manufacturing method of the laminated magnetic material of the present embodiment, that is, the thermosetting or normal temperature setting resin is the resin described above.

The step of applying a resin is a step of placing a resin on one side or both sides of the quenched alloy ribbon 1 to form the resin layer 2 . The method for forming the resin layer 2 is not particularly limited. After that, there is a method of evaporating the solvent.
In particular, the method of forming the resin layer 2 by applying a resin using a flexographic printing method is often used when applying a thermosetting resin that does not contain a solvent.

In the step of curing the resin, after the step of applying the resin, another quenched alloy ribbon 1 is superimposed on the surface of the quenched alloy ribbon 1 coated with the resin, pressed with a roller or the like, and heated to the curing temperature of the resin. It is a process of heating and hardening.

Next, a transformer core that is an embodiment of the present invention will be described. In the transformer core of the present embodiment, a plurality of laminated magnetic materials 11 are arranged so that the end surfaces perpendicular to the lamination direction of the plurality of laminated magnetic materials 11 abut against each other to form an annular transformer core. FIG. 5 is a perspective view showing one embodiment of a transformer core, which is an embodiment of the present invention. Four laminated magnetic materials 11 are used to form a rectangular transformer core as a whole. Here, the shape of the transformer core is not limited to this embodiment.

As the quenched alloy ribbon 1, a soft magnetic amorphous alloy ribbon made of 2605HB1M manufactured by Hitachi Metals, Ltd. and having a length of 120 mm, a width of 25 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 induced magnetic anisotropy in which the direction is the direction of easy magnetization.
Here, the coefficient of linear expansion of 2605HB1M is 4.3×10 ⁻⁶ [1/K].
It was also confirmed that _PCM14/50 and B80, which are the magnetic properties of the soft magnetic amorphous alloy ribbon, are 0.114 W/kg and 1.55 T, respectively.

Examples and comparative examples of laminated magnetic materials were produced by bonding two soft magnetic amorphous alloy ribbons described above using resins having various adhesive stresses, and _PCM14/50 and magnetic flux density B80 were measured for each. .

As for the resin, as shown in Table 1 below, nine kinds of resins a1, b1, c1, d1, e1, f1, g1, h1, i1 and j1 were prepared. Resins a1, b1, c1, d1 and e1 were used in Examples, and resins f1, g1, h1 and i1 were used in Comparative Examples.
Here, the curing temperature, curing type, durometer hardness, resin layer thickness, elastic modulus, linear expansion coefficient, thermal contraction coefficient, linear contraction coefficient during curing, and adhesive stress of each resin are as shown in Table 1. The modulus of elasticity, the coefficient of linear expansion, and the coefficient of linear shrinkage during curing are based on the results measured by the above-described measurement methods. The thermal contraction rate δ is expressed by the following formula, where α1 is the linear expansion coefficient of the resin, Ta is the curing temperature of the resin, α2 is the linear expansion coefficient of the amorphous alloy ribbon, and RT (=296 K) is the room temperature. be.

For the linear expansion coefficient α2 of the amorphous alloy ribbon, 4.3×10 ⁻⁶ [1/K] was used.

As for the curing type, there are a one-liquid type that contains a curing agent in advance and cures by heating, and a two-liquid type that cures by mixing a curing agent and a main agent at the time of use.
Durometer hardness is measured by using a durometer hardness tester (rubber hardness tester) to press a type D (A) indentation against the surface of the test piece with a specified spring force. It is the hardness obtained from the depth, and refers to the value measured by the test method specified in JIS K7215.
The adhesive stress σ [MPa] uses the elastic modulus, linear expansion coefficient, linear shrinkage coefficient at the time of curing, and curing temperature of each resin shown in Table 1, and the linear expansion coefficient of the amorphous alloy ribbon is 4.3 × 10 ⁻⁶ [1/K], and the room temperature is 300 [K], and the value is calculated from the above formula (Equation 1).

[Preparation of sample]
The resins of Examples 1 to 5 and Comparative Examples 1 to 4 shown in Table 1 were applied to the entire surface of the soft magnetic amorphous alloy ribbon using a flexographic printing method, the other soft magnetic amorphous alloy ribbon was superimposed, and a roller was applied. crimped with Here, for the two-liquid type resin, the curing agent and main agent were mixed until uniform, and then applied by flexographic printing. After press-bonding, the materials that were cured at each curing temperature by heating or at room temperature were allowed to stand at room temperature for sufficient curing, and samples of Examples 1 to 5 and Comparative Examples 1 to 4 were prepared. A sample of Comparative Example 5 was prepared by laminating two soft magnetic amorphous alloy ribbons under their own weight without forming a resin layer.

As can be seen from Table 1, the thickness of the resin layer 2 after curing is between 1.9 μm and 4.9 μm in Examples 1 to 5, and between 2.9 μm and 6 in Comparative Examples 1 to 4. .7 μm.

(Magnetic properties)
_PCM14/50 and magnetic flux density B80 were measured for the prepared samples. Each magnetic property was measured in consideration of the cross-sectional area and mass of only the portion of the soft magnetic amorphous alloy ribbon bonded between the layers with the resin among the laminated magnetic materials. For _PCM14/50 , each sample was excited at a frequency of 50 Hz and a maximum magnetic flux density of 1.4 T, and iron loss (W/kg) at that time was measured. For B80, a magnetic field with a frequency of 50 Hz and 80 A/m was applied, and the magnetic flux density B80 was measured. In particular, the B80 of the entire laminated magnetic material is obtained by multiplying the magnetic flux density B80 measured in consideration of the cross-sectional area of only the portion of the soft magnetic amorphous alloy ribbon that is interlayer-bonded with resin by the space factor of the laminated magnetic material. calculated as

For each measurement, a BH loop analyzer SY8218 manufactured by Iwasaki Tsushinki Co., Ltd. was used as an AC magnetic characteristic measuring device, and an amplifier SY-5001 manufactured by PMK was used. Also, as a measuring jig, a frame for measurement was manufactured and used with reference to JISC2556 "Method for measuring magnetic properties of an electromagnetic steel strip using a single plate tester". The jig construction consists of a MnZn ferrite yoke, a resin bobbin and polyurethane-coated copper wire. A primary winding (exciting coil) (wire diameter: 0.5 mm) and a secondary winding (B coil) (wire diameter: 0.5 mm) were applied to a resin bobbin with 57 and 100 turns of polyurethane-coated copper wire, respectively. A ribbon was inserted and a magnetic field was applied to the ribbon with a bobbin length of 36.2 mm. In the measurement, the ribbon was sandwiched between upper and lower MnZn ferrite yokes. By sandwiching the ribbon between the MnZn ferrite yokes, the flow of the magnetic flux is made into a closed magnetic path, and the generation of the demagnetizing field in the ribbon can be prevented. In addition, the background caused by the MnZn ferrite yoke and the air gap between the coil and the magnetic material was measured by connecting a compensating coil between the jig and the SY8218 and applying a magnetic field of 8000 A/m. The number of turns of the compensating coil was adjusted so that the output of was zero.
Table 2 shows the measurement results of each sample.

As can be seen from Tables 1 and 2, in Examples 1 to 5 in which the adhesive stress is 3 MPa or less, the B80 of the soft magnetic amorphous alloy ribbon portion bonded between layers with resin is 1.4 T or more, and the _PCM14/50 is 0. 0.26 W/kg or less, and had good magnetic properties for use in commercial frequency band transformers. In particular, in Examples 1 and 2 at 0.6 MPa or less, the B80 of the portion of the soft magnetic amorphous alloy ribbon bonded between the layers with the resin is 1.5 T or more, and the B80 of the entire laminated magnetic material is 1.4 T or more, and the P _CM14/50 of 0.16 W/kg or less, which indicates a B80 of 90% or more versus the unbonded Comparative Example 5, and an increase in _PCM14/50 of 17% or less, which is very good. It shows magnetic properties.
Here, as in Examples 1 to 5, it was found that good magnetic properties were obtained when a resin having an elastic modulus of 2600 MPa or less was used. Further, from Tables 1 and 2, it can be seen that the linear shrinkage rate of the cured resin is preferably 0.8% or less. It is also found that the heat shrinkage rate δ of the resin is preferably 0.3% or less.

(Peel strength evaluation)
Table 3 shows the peel strength evaluation results of the samples of Examples 1 to 5 and Comparative Examples 1 to 4 using the peel strength measurement method described above. As Comparative Example 6, a two-layer laminate was produced using polyester resin j1, which is a hot-melt thermoplastic resin, and its peel strength was also evaluated. In addition, in order to evaluate the heat resistance, the peel strength at a high temperature of 70° C. was measured for Examples 1 to 5 and Comparative Example 6.

Examples 1 to 5 and Comparative Example 6 exhibit sufficient peel strength of 1.0 gf/mm or more at room temperature. On the other hand, at a high temperature of 70 ° C., Examples 1 to 5 maintained a peel strength of 1.0 gf / mm or more, and the peel strength change rate (vs. Room temperature ratio) also confirmed an increase in peel strength of less than 90%. However, in Comparative Example 6, the peel strength was less than 1.0 gf/mm, and a large decrease in peel strength was confirmed even at room temperature. Therefore, it can be seen that the thermosetting or normal-temperature-setting resins such as those of Examples 1 to 5 are adhesives with excellent heat resistance, in which the peel strength is less likely to decrease even at high temperatures.

As described above, according to the present embodiment, it is possible to provide an excellent laminated magnetic material, a core for a transformer, and a method for manufacturing the laminated magnetic material, which are excellent in heat resistance, maintain a high magnetic flux density, and have little iron loss.

Although the present invention has been described using the above embodiments, the technical scope of the present invention is not limited to the above embodiments.

1 Quenched alloy ribbons 1a, 1b Main surface of quenched alloy ribbon 2 Resin layer 3 Peel strength measuring device 3a Clip 3b Force gauge 3c Linear guide 3d Metal base 3e Double-

sided tape

11, 12 Laminated magnetic material

Claims

A laminated magnetic material in which the laminated quenched alloy ribbons are thermosetting or room temperature curable and interlayer bonded with a resin having a glass transition temperature of 100 ° C. or less,
A laminated magnetic material having a peel strength of 1.0 gf/mm or more at room temperature and a magnetic flux density B80 of 1.25 T or more at an applied magnetic field of 80 A/m for the entire laminated magnetic material. material.
The magnetic flux density B80 of the quenched alloy ribbon bonded between layers with the resin is 1.4 T or more at an applied magnetic field of 80 A/m, and the iron loss Pcm at a frequency of 50 Hz and a maximum magnetic flux density of 1.4 T is 0.26 W/kg. The laminated magnetic material according to claim 1, characterized by:
γ [MPa] is the elastic modulus of the resin at room temperature, α1 [1/K] is the linear expansion coefficient of the resin at room temperature, Ta [K] is the curing temperature of the resin, and Ta [K] is the linear shrinkage rate of the resin when cured. When β, the resin thickness of the resin is h1 [μm], the thickness of the quenched alloy ribbon is h2 [μm], the linear expansion coefficient of the quenched alloy ribbon is α2 [1/K], and the room temperature is RT 2. The laminated magnetic material according to claim 1, wherein the adhesive stress σ [MPa] represented by the following formula is 3 MPa or less.
σ = h1 / h2 × γ × {(α1-α2) × (Ta-RT) + β}
The laminated magnetic material according to claim 3, wherein the adhesive stress σ is 0.6 MPa or less.
The laminated magnetic material according to any one of claims 1 to 4, wherein the resin is at least one of epoxy resin, epoxy-modified silicone resin, and acrylic resin.
A transformer core comprising the laminated magnetic material according to claim 5.
A method for manufacturing a laminated magnetic material in which laminated quenched alloy ribbons are bonded between layers with a resin that is thermosetting or room temperature setting and has a glass transition temperature of 100° C. or less,
a step of applying the resin to one side or both sides of the quenched alloy ribbon;
A method for producing a laminated magnetic material, comprising: laminating the quenched alloy ribbons and curing the resin.
The method for manufacturing a laminated magnetic material according to claim 7, wherein the resin is at least one of epoxy resin, epoxy-modified silicone resin, and acrylic resin.