JP2018125502A - Composite magnetic powder material, metal composite core and method for manufacturing metal composite core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide composite magnetic powder having a high magnetic property, a metal composite core and a method for manufacturing the metal composite core.SOLUTION: Magnetic powder is arranged by mixing first magnetic powder of 100-200 μm in average particle diameter and second magnetic powder of 5-10 μm in average particle diameter. A method for manufacturing a metal composite core comprises: a coating step of adding 0.25-1.0 wt.% of a titanium phosphate-based oligomer to the magnetic powder to form an insulative coating on the magnetic powder; a mixing step of mixing the magnetic powder with a resin; a molding step of putting the mixture obtained in the mixing step in a predetermined container to mold it; and a curing step of curing the resin in a mold obtained in the molding step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composite magnetic powder material comprising a magnetic powder and a resin, a metal composite core, and a method for producing a metal composite core.

  Reactors are used in various applications such as office automation equipment, solar power generation systems, automobiles, and uninterruptible power supplies. The reactor is used, for example, in a filter that prevents the harmonic current from flowing out to the output system, a voltage raising / lowering converter that raises or lowers the voltage, and the like.

  The reactor is required to have magnetic characteristics such as magnetic permeability, inductance value, and iron loss according to the application. For example, a reactor used for a voltage raising / lowering converter is required to improve energy conversion efficiency, and thus is required to have a small iron loss as an energy loss.

  Moreover, in order to respond | correspond to various uses, there exists a request to shape | mold the core used for a reactor in arbitrary shapes. As a reactor that meets such a demand, there is a reactor equipped with a core type called a metal composite core.

  A metal composite core (hereinafter, also simply referred to as MC core) is a core formed by molding a material obtained by mixing metal magnetic powder and resin into a predetermined shape and solidifying it. The conventional MC core is in the form of a slurry, is easy to pour the material into a container, and has an advantage in moldability that can form a predetermined shape.

JP 2012-33727 A

  The MC core has a flat magnetic characteristic. That is, the MC core is less likely to be magnetically saturated than the ferrite core, and has a characteristic that the permeability is less likely to decrease even when the current flowing through the coil is increased. That is, in other words, the MC core has a characteristic that the initial permeability, that is, the permeability when no current flows through the coil tends to be low. Although the MC core has such excellent characteristics, further improvement in magnetic characteristics is expected in recent years.

  An object of the present invention is to provide a composite magnetic powder material having high magnetic properties, a metal composite core, and a method for producing the metal composite core.

  In order to achieve the above object, a method for producing a metal composite core according to the present invention is a method for producing a metal composite core containing a magnetic powder and a resin, wherein the magnetic powder is a first magnetic material having a predetermined average particle diameter. A powder and a second magnetic powder having an average particle size smaller than the first magnetic powder, and adding 0.25 to 1.0 wt% of a titanium phosphate oligomer to the magnetic powder, A coating step of forming an insulating coating on the magnetic powder; a mixing step of mixing the resin with the magnetic powder; a molding step of molding the mixture obtained in the mixing step in a predetermined container; and the molding step And a curing step for curing the resin in the molded body obtained in (1).

  The metal composite core of the present invention is a metal composite core comprising a magnetic powder and a resin, and the magnetic powder includes a first magnetic powder having an average particle diameter of 100 to 200 μm and an average particle diameter of 5 to 10 μm. Wherein the first magnetic powder is covered with an insulating coating derived from a titanium phosphate oligomer.

  Furthermore, the magnetic powder material of the present invention is a composite magnetic powder material comprising a magnetic powder and a resin, and the magnetic powder has a first magnetic powder having an average particle diameter of 100 to 200 μm and an average particle diameter of 5 to 5. 10 μm of second magnetic powder, wherein the first magnetic powder is covered with an insulating film containing titanium oxide and phosphoric acid.

  ADVANTAGE OF THE INVENTION According to this invention, the magnetic powder material of the outstanding magnetic characteristic which reduced the eddy current loss, the metal composite core, and the manufacturing method of a metal composite core can be provided.

It is a flowchart for demonstrating the manufacturing method of the metal composite core which concerns on embodiment. It is a figure for demonstrating a formation process and a pressurization process. It is a graph which shows the relationship between the addition amount of the titanium phosphate oligomer in the 1st characteristic comparison, and the iron loss Pcv. It is a graph which shows the relationship between the addition amount of the titanium phosphate oligomer in the first characteristic comparison, the initial permeability μ0, and the density. It is a SEM image (x500) of comparative example 1 in the 1st characteristic comparison.

[1. Embodiment]
[1-1. Constitution]
The magnetic powder material of this embodiment includes magnetic powder and resin. Two types of magnetic powders having different average particle diameters are used as the magnetic powder contained in the magnetic powder material. An insulating coating derived from a titanium phosphate oligomer is formed around a powder having a larger average particle size among magnetic powders. Then, two kinds of magnetic powder and resin are mixed to obtain a clay-like magnetic powder material. In addition, the metal composite core of the present embodiment fills a predetermined container with a clay-like magnetic powder material and pressurizes the core into a predetermined shape. The shape of the core can be various shapes such as a toroidal core, an I-type core, a U-type core, a θ-type core, an E-type core, and an EER-type core.

(Magnetic powder)
The magnetic powder is composed of two types of magnetic powders having different average particle diameters. The magnetic powder is composed of a first magnetic powder and a second magnetic powder having an average particle diameter smaller than that of the first magnetic powder. The weight ratio of the first magnetic powder and the second magnetic powder is preferably set to the first magnetic powder: second magnetic powder = 80: 20 to 60:40. By setting it in this range, the density is improved, the magnetic permeability is improved, and the iron loss can be reduced.

  The average particle diameter of the first magnetic powder is preferably 100 μm to 200 μm, and the second magnetic powder is preferably 5 μm to 10 μm. By mixing two kinds of magnetic powders having different average particle diameters, the second magnetic powder having a small average particle diameter enters the gap between the first magnetic powders. Thereby, improvement of density and magnetic permeability and reduction of iron loss can be achieved.

  As the first magnetic powder and the second magnetic powder, soft magnetic powder can be used, and in particular, Fe powder, Fe-Si alloy powder, Fe-Al alloy powder, Fe-Si-Al alloy powder (Sendust), or A mixed powder of these two or more powders can be used. As the Fe—Si alloy powder, for example, Fe-6.5% Si alloy powder and Fe-3.5% Si alloy powder can be used. The average particle diameter (D50) of the soft magnetic powder is preferably 20 μm to 150 μm. In the present specification, the “average particle diameter” refers to D50, that is, the median diameter unless otherwise specified.

  The first magnetic powder and the second magnetic powder are preferably spherical. The circularity of the first magnetic powder is preferably 0.90 or more, and the circularity of the second magnetic powder is preferably 0.94 or more. This is because the gap between the first magnetic powders is reduced and more second magnetic powder can easily enter the gap, and the density and permeability can be improved.

  Note that the types of the first magnetic powder and the second magnetic powder may be the same or different. If different, three or more may be used.

  The first magnetic powder is preferably a pulverized powder or a powder produced by a gas atomizing method. Moreover, you may approximate to a spherical shape by performing the planarization process by a process. The second magnetic powder is preferably produced by a water atomizing method, a gas atomizing method, or a water / gas atomizing method.

(Insulation coating)
The first magnetic powder that molds the core is covered with an insulating coating having insulating properties. The insulating coating is a coating derived from a titanium phosphate oligomer. The thickness of the insulating coating is preferably 10 nm to 100 nm. By coating the titanium phosphate oligomer on the magnetic powder, it becomes possible to form an insulating film of 10 nm to 100 nm. The insulating coating is formed by solidification of the titanium phosphate oligomer and includes titanium oxide and phosphoric acid. As the titanium phosphate oligomer used, a titanium phosphate oligomer having a titanium content of 10.0 wt% is used. Moreover, the addition amount of the titanium phosphate oligomer is preferably in the range of 025 to 1.0 wt% with respect to the first magnetic powder. By adding a predetermined amount of a titanium phosphate oligomer having a predetermined titanium content, an insulating film having a thickness of 10 nm to 100 nm can be formed around the first magnetic powder. On the other hand, when the addition amount of the titanium phosphate oligomer is less than 0.25 wt%, the thickness of the insulating coating becomes thinner than 10 nm, and thus the effect of reducing eddy current loss (Pe) is low. When the added amount of titanium phosphate oligomer exceeds 1.0 wt%, the thickness of the insulating coating becomes thicker than 100 nm, and it is possible to reduce eddy current loss (Pe), but the density of the MC core decreases. This adversely affects the magnetic properties of the MC core. The deterioration of magnetic characteristics is, for example, an increase in Ph and a decrease in initial permeability μ0.

(resin)
The resin is mixed with the magnetic powder and holds the mixed magnetic powder. When the magnetic powder is composed of different types of powders having different average particle sizes, each powder is held in a homogeneously mixed state. As the resin, a thermosetting resin, an ultraviolet curable resin, or a thermoplastic resin can be used. As the thermosetting resin, phenol resin, epoxy resin, unsaturated polyester resin, polyurethane, diallyl phthalate resin, silicone resin and the like can be used. As the ultraviolet curable resin, urethane acrylate, epoxy acrylate, acrylate, and epoxy resins can be used. As the thermoplastic resin, it is preferable to use a resin having excellent heat resistance such as polyimide or fluororesin. An epoxy resin that is cured by adding a curing agent is suitable for the present invention because its viscosity can be adjusted by the amount of the curing agent added. Thermoplastic acrylic resins and silicone resins can also be used.

  It is preferable that 3-5 wt% of resin is contained with respect to the magnetic powder. When the resin content is less than 3 wt%, the bonding strength of the magnetic powder is insufficient and the mechanical strength of the core is lowered. Also, if the resin content is more than 5 wt%, the resin formed between the first magnetic powder enters, the second magnetic powder cannot fill the gap, and the core density decreases, The initial permeability μ0 decreases.

  The viscosity of the resin is preferably 50 to 5000 mPa · s when mixed with the magnetic powder. When the viscosity is less than 50 mPa · s, the resin does not get entangled with the magnetic powder during mixing, the magnetic powder and the resin are easily separated in the container, and the density or strength of the core varies. When the viscosity exceeds 5000 mPa · s, the viscosity becomes too high. For example, the resin formed between the first magnetic powders enters, and the gap cannot be filled with the second magnetic powder. Decreases, and the initial permeability μ0 decreases.

For the resin, SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , BN, AlN, ZnO, TiO ₂ or the like can be used as a viscosity adjusting material. The average particle diameter of the filler as the viscosity adjusting material is not more than the average particle diameter of the second magnetic powder, preferably not more than 1/3 of the average particle diameter of the second magnetic powder. This is because when the average particle size of the filler is large, the density of the obtained core decreases. Further, a high thermal conductivity material such as Al ₂ O ₃ , BN, or AlN can be added to the resin.

  The ratio of the apparent density of the core to the true density of the magnetic powder is preferably more than 76.47%, and more preferably 77.5% or more. When the ratio is more than 76.47%, the magnetic permeability can be increased. On the other hand, when the ratio is 76.47% or less, low permeability results in low magnetic permeability.

(coil)
The coil is a conducting wire with an insulating coating, and a copper wire or an aluminum wire can be used as the wire. The coil is formed or mounted by winding a conductive wire around at least a part of the core, and is arranged around at least a part of the core. There are no particular limitations on the method of winding the coil and the material and shape of the wire.

[1-2. Manufacturing method of metal composite core]
The manufacturing method of the metal composite core which concerns on this embodiment is demonstrated referring drawings. As shown in FIG. 1, the manufacturing method of the present metal composite core includes (1) a coating process, (2) a mixing process, (3) a molding process, (4) a pressing process, and (5) a curing process.

(1) Coating process The coating process is a coating process for coating magnetic powder. In the coating step, at least the first magnetic powder is coated with an insulating coating derived from a titanium phosphate oligomer. In the coating step, the first magnetic powder and the titanium phosphate oligomer are mixed and dried to form a film containing titanium oxide and phosphoric acid around the first magnetic powder. The coating step can be performed automatically using a predetermined mixer or manually. The mixing time of each coating step can be set as appropriate and is not particularly limited, but is, for example, 2 minutes. The drying temperature and time in the coating step can be appropriately set as long as the temperature and time are necessary for forming a coating containing titanium oxide and phosphoric acid. By passing through the coating step, an insulating coating containing titanium oxide derived from a titanium phosphate oligomer and phosphoric acid is formed around the first magnetic powder.

(2) Mixing step The mixing step is a step of mixing magnetic powder and resin. In the mixing step, the first magnetic powder and the second magnetic powder having an average particle diameter smaller than that of the first magnetic powder are mixed, and the magnetic powder mixing step for forming the magnetic powder, A resin mixing step of adding 5 wt% resin and mixing the magnetic powder and the resin.

  The mixing in each mixing step can be performed automatically using a predetermined mixer or manually. The mixing time of each mixing step can be set as appropriate, and is not particularly limited.

  By such a mixing step, a mixture of magnetic powder and resin (hereinafter also referred to as a composite magnetic material) can be obtained. In the mixing step, the magnetic powder and the resin may be filled and mixed in a container for molding the composite magnetic material in the molding step. Thereby, it is not necessary to transfer a composite magnetic material to a container, and a manufacturing man-hour can be reduced.

(3) Molding process The molding process is a process in which the composite magnetic powder is put into a container having a predetermined shape and molded into a predetermined shape. In the molding step, a coil may be put together with the composite magnetic powder and molded.

  As a container, the thing of various shapes is used according to the shape of the core to manufacture. When inserting a coil, the container uses a box-type container or a dish-shaped container with an open top so that the coil can be inserted from above. The container used in the molding process can also be used as an outer case of a metal composite core that accommodates the core and the coil as it is. If the container is used as an exterior case, there is an advantage that it is not necessary to take out the container after the composite magnetic powder is cured. When the container is not used as an exterior case, a plurality of metal composite cores may be manufactured with one container. That is, a plurality of recesses may be formed at the bottom of the container, and a plurality of metal composite cores may be manufactured by placing a composite magnetic material and a coil in the recesses. By doing in this way, since a single shaping | molding process may be sufficient with respect to a some metal composite core, manufacturing efficiency can be improved.

  As a container used for a molding process, all or a part thereof can be constituted by a resin molded product. By making the container made of resin, the manufacturing cost can be reduced, and the advantage that the MC core can have any shape can be utilized. That is, since the resin is a comparatively inexpensive material, the cost of manufacturing the container can be suppressed, and a core having an arbitrary shape can be formed by injection molding or the like.

  Moreover, you may comprise all or one part of a container with metals with high heat conductivity, such as aluminum and magnesium. This is because the composite magnetic material can be easily warmed in the pressurizing step, as will be described later.

(3) Pressurization step The pressurization step is a step of pressing the composite magnetic material with a pressing member during the molding step. By pressing the clay-like composite magnetic material contained in the container with the pressing member, the composite magnetic material is expanded to the shape of the container, and the voids contained in the composite magnetic material are reduced, the apparent density, and Improve initial permeability.

  When the coil is not put in the container, the composite magnetic material becomes a shape inside the container by the process. That is, a molded body having a predetermined shape made of a composite magnetic material can be obtained.

  When putting a coil in a container, as shown in FIG. 2, a composite magnetic material is put in a container, and a composite magnetic material is spread in the shape of a container by a pressing member. Thereafter, the coil is inserted into the space formed by pressing the composite magnetic material, and further filled with the composite magnetic material, and the composite magnetic material is pressed together with the coil from above by the pressing member. Alternatively, the composite magnetic material may be placed in a container, and then the coil may be embedded in the composite magnetic material, and the composite magnetic material may be pressed together with the coil from above. Thus, by pressing a composite magnetic material with a coil, the space | gap contained in the composite magnetic material can be reduced and an apparent density and a magnetic permeability can be improved. In addition, you may make it press only a composite magnetic material, avoiding the part in which a coil exists. In this way, a molded body of a composite magnetic material having a predetermined shape including a coil can be obtained by this process.

  Thus, the pressurizing step may press the composite magnetic material with the pressing member to make the material into the shape of the container. In this case, the pressurizing step can be regarded as the pressurizing step and the molding step. .

The pressure for pressing the composite magnetic material is preferably 2.0 kg / cm ² or more. If it is less than this value, the pressure to press is small and the effect of improving the apparent density is small. Moreover, even if it is more than the said value, it is preferable that it is 10.0 kg / cm < ² > or less. This is because even if pressing exceeds this value, the effect of improving the apparent density is small.

  The time for pressing the composite magnetic material can be appropriately changed depending on the resin content and viscosity. For example, it can be 10 seconds.

  The pressing step may be performed by setting the pressing member that presses the container or the composite magnetic material to a temperature higher than normal temperature (for example, 25 ° C.). By raising the temperature of the container or the pressing member, the resin is warmed and softened. Therefore, the composite magnetic material can easily flow into the gap in the container, and the moldability can be improved, and the material can easily flow into the voids in the composite magnetic material, and the apparent density can be improved. The temperature of the pressing member that presses the container or the composite magnetic material is preferably higher than the softening point of the resin contained in the composite magnetic material. This is because the resin can be effectively softened. The pressurizing step may be performed while maintaining the temperature of the pressing member that presses the container or the composite magnetic material.

  In the pressurizing step, the temperature of the container or the pressing member may be raised, or the composite magnetic material itself may be heated to press the composite magnetic material. The temperature of the pressing member that presses the container or the composite magnetic material may be maintained, and the composite magnetic material itself may be warmed and pressed.

(4) Curing step The curing step is a step of curing the resin in the molded body obtained in the molding step. In the case of curing by drying the resin in the molded body, the drying atmosphere can be an air atmosphere. In the curing step, the resin is cured by a drying profile that controls the drying temperature and time based on the dry state of the resin. Although drying time can be suitably changed according to the kind of resin, content, drying temperature, etc., for example, although it can be made into 1 hour-4 hours, it is not limited to this. Although drying temperature can be suitably changed according to the kind of resin, content, drying time, etc., for example, although it can be set as 85 to 150 degreeC, it is not limited to this. The drying temperature is the temperature of the drying atmosphere.

  The curing of the resin is not limited to drying, and the curing method varies depending on the type of resin. For example, if the resin is a thermosetting resin, the resin is crossed by applying heat, and if the resin is an ultraviolet curable resin, the resin is cured by irradiating the molded body with ultraviolet rays.

  In the curing step, the step of curing the molded body for a predetermined time at a predetermined temperature may be repeated a plurality of times. Further, for example, when the resin is cured by drying, the drying temperature or the drying time may be changed every time the resin is repeated a plurality of times.

[1-3. Action / Effect]
(1) The method for producing a metal composite core of the present embodiment is a method for producing a metal composite core comprising a core containing magnetic powder and resin, and a coil attached to the core. It consists of the 1st magnetic powder of a particle diameter, and the 2nd magnetic powder whose average particle diameter is smaller than the 1st magnetic powder. A coating step of adding 0.25 to 1.0 wt% of a titanium phosphate oligomer to the magnetic powder to form an insulating coating containing titanium oxide and phosphoric acid on the magnetic powder; A mixing step of mixing the resin, a molding step of molding the mixture obtained in the mixing step in a predetermined container, and a curing step of curing the resin in the molded body obtained in the molding step. I made it.

(Suppression of contact between powders)
Thereby, the metal composite core of the outstanding magnetic characteristic which reduced the eddy current loss can be obtained. In the MC core, stress is applied to the magnetic powder in the molding process and the pressing process. This stress may cause the magnetic powders to contact each other. By covering the surface of the soft magnetic powder with an insulating film containing phosphoric acid of titanium oxide derived from a titanium phosphate oligomer, contact between the soft magnetic powders can be suppressed. Since an eddy current corresponding to the size of the soft magnetic powder is generated, a larger eddy current is generated when the soft magnetic powders are in contact with each other. This does not matter the type of soft magnetic powder. Further, the number of magnetic powders in contact is not limited. That is, a larger eddy current may be generated when a plurality of magnetic powders come into contact with each other. In the metal composite core of this embodiment, it becomes possible to suppress generation | occurrence | production of a big eddy current by suppressing the contact of magnetic powder with an insulating film. The effect of suppressing the eddy current loss by the insulating coating is not limited to the case where only the first magnetic powder is covered with the insulating coating. That is, eddy current loss is also suppressed when both the first magnetic powder and the second magnetic powder are covered with an insulating coating. Further, although the effect is limited, the effect of suppressing eddy current loss can be expected even when only the second magnetic powder is covered with an insulating film. On the other hand, in the manufacture of the MC core, the density decreases as the proportion of the titanium phosphate oligomer and the resin increases.

(Titanium phosphate oligomer)
The insulating coating formed around the magnetic powder of this embodiment contains titanium oxide derived from a titanium phosphate oligomer and phosphoric acid. In the coating step in the MC core, an insulating film having a thickness of 10 to 100 nm can be formed around the magnetic powder by using a titanium phosphate oligomer. Thereby, it becomes possible to suppress the eddy current loss of the MC core while suppressing the decrease in density. Titanium phosphate oligomers have good film formability. Therefore, generation | occurrence | production of the void at the time of coating | covering the surface of a magnetic powder with a titanium phosphate type oligomer can be suppressed in a coating process. Moreover, since the titanium phosphate oligomer is difficult to decompose, generation of voids due to decomposition of the titanium phosphate oligomer can also be suppressed. Further, the formed insulating film is formed of an oxide film of titanium which is a stable metal. Therefore, it becomes an insulating film having strength and resistance. Moreover, since the insulating coating contains phosphoric acid, a rust prevention effect is obtained.

(2) In the coating step of the present embodiment, the first magnetic powder and the titanium phosphate oligomer are mixed to form an insulating film containing titanium oxide and phosphoric acid on the first magnetic powder. In the MC core, an eddy current corresponding to the size of the magnetic powder is generated. In the first magnetic powder having a large average particle size, a large eddy current is generated, which has an advantageous effect on the eddy current loss in the MC core. When the first magnetic powders come into contact with each other, a larger eddy current is generated, which adversely affects eddy current loss in the MC core. According to this embodiment, the periphery of the first magnetic powder is covered with the insulating coating. As a result, the contact between the first magnetic powders can be suppressed, and the generation of a large eddy current due to the contacted first magnetic powder can be suppressed, thereby realizing an MC core with low eddy current loss. can do.

(3) The magnetic powder is a mixture of the first magnetic powder and the second magnetic powder having an average particle diameter smaller than that of the first magnetic powder, and the added amount of the first magnetic powder in the magnetic powder is 70 wt. %, And the second magnetic powder was 30 wt%. Thereby, the second magnetic powder enters the gap between the first magnetic powders, and the density and magnetic permeability can be improved and the iron loss can be reduced.

(4) As the resin, a thermosetting resin, an ultraviolet curable resin, or a thermoplastic resin can be used, but it is particularly preferable to use a resin having good heat resistance. By using a resin having high heat resistance such as an epoxy resin, an MC core having good heat resistance can be manufactured.

(5) A pressing step of pressing the mixture is provided during the molding step. Thereby, the density of a core can be improved. Moreover, it is desirable that the pressurizing pressure in the pressurizing step is 2.0 to 10.0 kg / cm ² . Thereby, the apparent density can be improved. As a result of pressurization at a pressurization pressure of 2.0 to 10.0 kg / cm ² , the apparent density of the MC core becomes more than 76.47%.

(6) The pressurizing step was performed by setting the member that presses the container or the mixture to a temperature higher than room temperature. Thereby, the resin in the composite magnetic material which is the mixture is warmed and softened. For this reason, the composite magnetic material can easily flow into every corner of the container and the moldability can be improved, and the material can easily flow into the voids in the composite magnetic material, and the density can be improved.

(7) The pressurizing step was performed by putting the mixture warmed to a temperature higher than normal temperature into the container. Thereby, the same effect as said (6) can be acquired.

[1-4. Example]
Examples of the present invention will be described below with reference to Tables 1 to 3 and FIGS. 3 to 5.
(1) Measurement items Measurement items are density, magnetic permeability, iron loss, and inductance value (L value). A 40-turn winding was applied to each of the prepared core samples with a copper wire of φ1.2 mm to prepare a metal composite core. The shape of each core sample was a toroidal shape having an outer diameter of 35 mm, an inner diameter of 20 mm, and a height of 11 mm. Moreover, the magnetic permeability of the produced reactor and the iron loss were computed on condition of the following.

<Density>
The density of the core is the apparent density. That is, the outer diameter, inner diameter, and height of the sample of each core were measured, and the volume (cm ³ ) of the sample was calculated from these values based on π × (outer diameter ² −inner diameter ² ) × height. Then, the mass of the sample was measured, and the density of the core was calculated by dividing the measured mass by the calculated volume.

<Permeability and iron loss>
The measurement conditions for magnetic permeability and iron loss were a frequency of 20 kHz and a maximum magnetic flux density Bm = 30 mT. The magnetic permeability was the amplitude magnetic permeability when the maximum magnetic flux density Bm was set when measuring the iron loss Pcv. The iron loss was calculated using a BH analyzer (Iwatori Measurement Co., Ltd .: SY-8232), which is a magnetic measurement device. This calculation was performed by calculating the hysteresis loss coefficient and the eddy current loss coefficient of the iron loss frequency curve by the following method (1) to (3) by the least square method.

Pcv = Kh × f + Ke × f ² (1)
Phv = Kh × f (2)
Pev = Ke × f ² (3)
Pcv: Iron loss Kh: Hysteresis loss coefficient Ke: Eddy current loss coefficient f: Frequency Phv: Hysteresis loss Pev: Eddy current loss

In this example, the average particle diameter and the circularity of each powder are the average values of 3000 pieces using the following apparatus. The powder is dispersed on a glass substrate, and a powder photograph is taken with a microscope. Each shot was automatically measured from the image.
Company name: Malvern
Device name: morphologic G3S
The specific surface area was measured by the BET method.

[First characteristic comparison (comparison of added amount of titanium phosphate oligomer)]
In the first characteristic comparison, the characteristics are compared by changing the amount of the titanium phosphate oligomer mixed with the first magnetic powder.

(2) Sample preparation method As the core sample, a plurality of samples were prepared by changing the addition amount of the titanium phosphate oligomer as described below. These production methods and the results are shown below in order.

  As the first magnetic powder, Fe6.5Si having an average particle diameter of 123 μm is used. 0.001 to 1.25% of a titanium phosphate oligomer is mixed with the first magnetic powder, and then dried at 150 ° C. for 2 hours. Generate.

  Next, Fe6.5Si having an average particle diameter of 5.1 μm is prepared as the second magnetic powder. Then, the first magnetic powder and the second magnetic powder having an insulating coating formed around them are mixed at a weight ratio of 70:30 to obtain a mixture of two magnetic powders having different average particle diameters. And the said magnetic powder was put into the aluminum cup, 3.5% of epoxy resin was added with respect to the said magnetic powder, and it mixed manually using the spatula for 2 minutes. This obtained the composite magnetic material which is a mixture of magnetic powder and resin.

Next, the composite magnetic material obtained in the mixing step is filled into a resin container having a toroidal space, and the composite magnetic material in the container is pressed with a 600 N press pressure (surface pressure 9.4 kg) using a hydraulic press. / Cm ² ) for 10 seconds to produce a toroidal shaped molded body. During this pressing, the temperature of the container was kept at 25 ° C.

  Thereafter, the copper wire was wound for 30 turns on the obtained molded body to form a coil, and a reactor as a base was produced.

  Then, the reactor is dried in the atmosphere at 85 ° C. for 2 hours, then dried at 120 ° C. for 1 hour, further dried at 150 ° C. for 4 hours to cure the resin, and a toroidal core as a sample is produced. Samples of Examples 1 to 5 and Comparative Examples 1 to 3 were obtained. The difference between Examples 1 to 5 and the comparative example is the addition amount of the titanium phosphate oligomer, and is 0.0 to 1.25 wt%, respectively.

Table 1 is a table showing the addition amount, density, initial magnetic permeability, magnetic permeability μ12000, iron loss Pcv (iron loss Pcv, hysteresis loss Phv, eddy current loss Pev) of the titanium phosphate oligomer. The permeability in Table 1 is the amplitude permeability, and was calculated from the inductance of the strength of each magnetic field at 20 kHz and 1.0 V by using the impedance analyzer described above. “Μ0” in Table 1 indicates the initial permeability when DC is not superimposed, that is, when the magnetic field strength is 0 H (A / m). “Μ12000” in Table 1 indicates the magnetic permeability when the magnetic field strength is 12 kH (kA / m).

  Based on Table 1, the graphs of FIGS. 3 and 4 were prepared. FIG. 3 is a graph showing the iron loss Pcv (iron loss Pcv, hysteresis loss Phv, eddy current loss Pev) with respect to the addition amount of the titanium phosphate oligomer, and FIG. 4 shows the initial transparency with respect to the addition amount of the titanium phosphate oligomer. It is a graph which shows a magnetic permeability and a density.

(Relationship between added amount of titanium phosphate oligomer and eddy current loss)
FIG. 5 is an SEM photograph (500 times) of the core cross section of Comparative Example 1. In FIG. 5, the code | symbol 1 shows the 1st magnetic powder with a large average particle diameter, and the code | symbol 2 shows the 2nd magnetic powder with a small average particle diameter. As shown in FIG. 5, in the sample of Comparative Example 1, the first magnetic powder, which is a large powder, and the first magnetic powder are partially in direct contact (region A). For this reason, the two first magnetic powders are electrically connected. Therefore, an eddy current due to the size of the two first magnetic powders is generated.

  As shown in Table 1 and FIG. 3, the effect of the insulating coating for suppressing the contact of the first magnetic powder is that the eddy current loss Pev in the case of not adding (Comparative Example 1) is 6.0 vs. When the addition amount of the titanium acid oligomer is 0.10% (Comparative Example 2), the eddy current loss is 5.8, and the effect is small. On the other hand, when the addition amount of the titanium phosphate oligomer is 0.25% or more, the eddy current loss Pev is 5.4 or less and the effect of suppressing the eddy current loss is exhibited, and the addition amount of the titanium phosphate oligomer is 0. Saturates at 75%.

  This is considered to be the result of suppressing the contact between the first magnetic powders by the insulating coating coated with the first magnetic powder. The magnitude of the eddy current generated in the magnetic powder is proportional to the size of the powder. For example, when a plurality of first magnetic powders come into contact with each other, an eddy current derived from a large magnetic powder is generated. In contrast, the addition of 0.25% or more of the titanium phosphate oligomer to the first magnetic powder to form an insulating film containing titanium oxide and phosphoric acid suppresses contact between the magnetic powders. As a result, low eddy current loss can be realized.

(Relationship between added amount of titanium phosphate oligomer and density)
There is a correlation between the thickness of the coating film formed around the first magnetic powder and the density of the sample. That is, as the amount of the titanium phosphate oligomer is increased and the thickness of the insulating coating is increased, the MC core density gradually decreases. The decrease in the density of the MC core affects the hysteresis loss Phv, the initial permeability, and the permeability (12 kH / m).

Hysteresis loss Phv As shown in Table 1 and FIG. 4, the hysteresis loss Phv when the insulating film is not formed around the first magnetic powder (Comparative Example 1) is 18.7. On the other hand, by adding 0.25 to 1.00% of the titanium phosphate oligomer and forming an insulating film around the first magnetic powder, the density is reduced but the hysteresis loss Phv is 17.6. It decreases to ˜18.3. However, when the addition amount of the titanium phosphate oligomer exceeds 1.00%, the hysteresis loss Phv becomes 19.8. This is because the hysteresis loss Phv due to the decrease in density increases more than the effect of reducing the hysteresis loss Phv by the insulating coating.

-Initial permeability and permeability (12 kH / m) As shown in Table 1 and FIG. 4, by adding a titanium phosphate oligomer and reducing the density of the MC core, the initial permeability and permeability ( 12 kH / m) decreases. When the added amount of the titanium phosphate oligomer exceeds 1.00%, the density becomes less than 5.81. For this reason, it turns out that it has a bad influence with respect to initial permeability and permeability (12 kH / m).

  As described above, from this characteristic comparison, it is preferable to add 0.25% or more of the titanium phosphate oligomer to the first magnetic powder from the viewpoint of low eddy current loss. From the viewpoint of magnetic permeability and magnetic permeability, it is possible to derive a result that the addition amount of the titanium phosphate oligomer is preferably 1.00% or less.

[Second characteristic comparison (characteristic comparison by the difference in magnetic powder forming the insulating coating)]
In the second characteristic comparison, the characteristics are compared by changing the magnetic powder forming the insulating coating.

(2) Sample preparation method In the second characteristic comparison, in addition to the core samples of Comparative Example 1 and Examples 2 and 4 used in the first characteristic comparison, A plurality of samples were prepared by changing the addition amount. These production methods and the results are shown below in order.

  As samples of Examples 7 and 8, Fe6.5Si having an average particle diameter of 123 μm is prepared as the first magnetic powder, and Fe6.5Si having an average particle diameter of 5.1 μm is prepared as the second magnetic powder. Then, 0.50% and 1.0% titanium phosphate oligomers were mixed with the first and second magnetic powders, and then dried at 150 ° C. for 2 hours to form an insulating film around the periphery. A first magnetic powder is produced. Then, the toroidal core used as a sample was produced by performing the same processing as other examples.

  As samples of Comparative Examples 8 and 9, Fe6.5Si having an average particle diameter of 123 μm is prepared as the first magnetic powder. As the second magnetic powder, Fe6.5Si having an average particle diameter of 5.1 μm is prepared. Then, 0.50% and 1.0% titanium phosphate oligomers were mixed with the second magnetic powder, and then dried at 150 ° C. for 2 hours, thereby forming an insulating coating around the second magnetic powder. Produces magnetic powder. Then, the toroidal core used as a sample was produced by performing the same processing as other examples.

Table 2 is a table showing the added amount, density, initial permeability, permeability μ12000, iron loss PcPcv (iron loss Pcv, hysteresis loss Phv, eddy current loss Pev) of the titanium phosphate oligomer.

(Relationship between magnetic powder forming insulating film and eddy current loss)
The effect of reducing eddy current loss is greatly influenced by the insulating film of the first magnetic powder. That is, as shown in Table 2, when the titanium phosphate oligomer is not added (Comparative Example 1), the eddy current loss is 6.0, while the titanium phosphate oligomer is 0 with respect to the first magnetic powder. When 0.5% to 1.0% is added (Examples 2 and 4), the eddy current loss Pev is 5.3 to 5.4. When 0.5% to 1.0% of the titanium phosphate oligomer was added to the first and second magnetic powders (Examples 7 and 8), the eddy current loss Pev was 5.3. Become. Furthermore, when 0.5% to 1.0% of the titanium phosphate oligomer is added to the second magnetic powder, the eddy current loss Pev is 5.4 to 5.8.

  As described above, in all of Examples 2, 4, 7, and 8, the eddy current loss Pev is reduced by forming the insulating film. On the other hand, in Comparative Examples 8 and 9, it is possible to suppress the contact of the second magnetic powder by forming a film only on the second magnetic powder. Since the generated eddy current is not large, the effect of reducing the eddy current loss Pev is limited.

(Relationship between magnetic powder and density forming insulating film)
Differences in the magnetic powder forming the insulating coating affect the density. That is, as shown in Table 2, when the titanium phosphate oligomer was not added (Comparative Example 1), the density was 6.06, and the titanium phosphate oligomer was 0.5 with respect to the first magnetic powder. In Examples 2 and 4 where% to 1.0% is added, the density is 5.71 to 5.90. In Examples 7 and 8, in which 0.5% to 1.0% of the titanium phosphate oligomer was added to the first and second magnetic powders, the density was 5.56 to 5.61.

  In each of Examples 2, 4, 7, and 8 and Comparative Examples 8 and 9, the density is reduced by forming any insulating film. The reduction rate is small in Examples 2 and 4 in which the film is formed only on the first magnetic powder, and small in Examples 7 and 8 in which the film is formed on the first magnetic powder and the second magnetic powder. . Furthermore, in Comparative Examples 8 and 9 in which a film is formed only on the second magnetic powder, the reduction rate is large.

Hysteresis loss Phv As shown in Table 2, the hysteresis loss Phv when the insulating film is not formed around the first magnetic powder (Comparative Example 1) is 18.7. On the other hand, the hysteresis loss of Example 2 and Example 4 is 17.1 to 18.3. In Examples 7 and 8 in which 0.5% to 1.0% of a titanium phosphate oligomer was added to the first and second magnetic powders, the hysteresis loss was 20.3% to 25.1. This is because the hysteresis loss Phv due to the decrease in density increases more than the effect of reducing the hysteresis loss Phv by the insulating coating.

  As described above, this characteristic comparison effectively suppresses eddy currents by forming an insulating film on the first magnetic powder regardless of the presence or absence of the insulating film of the second magnetic powder. It is understood that is possible. When Example 2 and Example 5 are compared, the effect of suppressing eddy currents hardly changes. On the other hand, when paying attention to the density, Example 2 in which a film is formed only on the first magnetic powder has a higher density. Therefore, it is more desirable to form a film only on the first powder.

[2. Other Embodiments]
The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  For example, in each embodiment, in order to reduce eddy current loss (Pe) while suppressing deterioration of magnetic characteristics, in order to form an insulating film of 10 nm to 100 nm around the first magnetic powder, On the other hand, although the titanium phosphate oligomer was added, it is not limited thereto. That is, if it is possible to form an insulating film having a thickness of 10 nm to 100 nm around the first magnetic powder, it is possible to substitute a titanium phosphate monomer.

  For example, in the embodiment, as a method of providing a coil in a reactor, a method of placing a coil in a container and embedding it in a composite magnetic material in a molding process has been described. However, a molded body of a predetermined shape made of a composite magnetic material is molded in advance. Alternatively, a method including a winding step of winding a conducting wire constituting the coil around the molded body may be adopted.

DESCRIPTION OF SYMBOLS 1 ... 1st magnetic powder 2 ... 2nd magnetic powder

Claims (16)

A method for producing a metal composite core containing magnetic powder and resin,
The magnetic powder is
A first magnetic powder having a predetermined average particle size;
A second magnetic powder having an average particle size smaller than the first magnetic powder;
Including
A coating step of adding 0.25 to 1.0 wt% of a titanium phosphate oligomer to the magnetic powder and forming an insulating coating on the magnetic powder;
A mixing step of mixing the resin with the magnetic powder;
A molding step of molding the mixture obtained in the mixing step into a predetermined container; and
A curing step of curing the resin in the molded body obtained in the molding step;
Providing
A method for producing a metal composite core characterized by In the coating step,
The method for producing a metal composite core according to claim 1, wherein the first magnetic powder and the titanium phosphate oligomer are mixed to form an insulating film on the first magnetic powder. The average particle diameter of the first magnetic powder is 100 to 200 μm,
3. The method for producing a metal composite core according to claim 1, wherein an average particle diameter of the second magnetic powder is 5 to 10 μm.   The addition amount of the first magnetic powder in the magnetic powder is 60 to 80 wt%, and the second magnetic powder is 20 to 40 wt%. Manufacturing method of metal composite core.   The method for producing a metal composite core according to any one of claims 1 to 4, wherein the resin is an epoxy resin. Including a pressing step of pressing the mixture during the molding step;
The method for producing a metal composite core according to any one of claims 1 to 5, wherein: The method for producing a metal composite core according to claim 6, wherein the pressurizing pressure in the pressurizing step is 2.0 to 10.0 kg / cm ² . The pressurizing step is performed by maintaining the member or the container for pressing the mixture at a temperature higher than room temperature;
The method for producing a metal composite core according to claim 6 or 7, wherein: The pressurizing step is performed by putting the mixture heated to a temperature higher than room temperature into the container,
The method for producing a metal composite core according to any one of claims 6 to 8. A metal composite core comprising magnetic powder and resin,
The magnetic powder is
A first magnetic powder having a predetermined average particle size;
A second magnetic powder having an average particle size smaller than the first magnetic powder;
Including
The metal composite core, wherein the first magnetic powder is covered with an insulating film derived from a titanium phosphate oligomer.   The metal composite core according to claim 10, wherein the insulating coating is a solidified product of the titanium phosphate oligomer.   The thickness of the said insulating film is 10-100 nm, The metal composite core of Claim 10 or Claim 11 characterized by the above-mentioned. The average particle diameter of the first magnetic powder is 100 to 200 μm,
13. The metal composite core according to claim 10, wherein an average particle diameter of the second magnetic powder is 5 to 10 μm.   The addition amount of the first magnetic powder in the magnetic powder is 60 to 80 wt%, and the second magnetic powder is 20 to 40 wt%. Metal composite core.   The metal composite core according to any one of claims 10 to 14, wherein an apparent density of the core is more than 76.47%. A composite magnetic powder material comprising magnetic powder and resin,
The magnetic powder is
A first magnetic powder having a predetermined average particle size;
A second magnetic powder having an average particle size smaller than the first magnetic powder;
Including
The composite magnetic powder material, wherein the first magnetic powder is covered with an insulating film containing titanium oxide and phosphoric acid.