JP5310989B2 - SOFT MAGNETIC MATERIAL, PROCESS FOR PRODUCING THE SAME, AND DUST MAGNETIC CORE CONTAINING THE SOFT MAGNETIC MATERIAL - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soft magnetic material which provides a dust core having small variations in volume resistivity value and strength even when annealed at a temperature of 700&deg;C high enough to eliminate strain generated in a green compact when compacted under high pressure, and to provide a dust core with high volume resistivity which contains the soft magnetic material. <P>SOLUTION: The soft magnetic material is made of composite particle powder having a first insulating layer having an inorganic compound sticking on or covering a particle surface of soft magnetic particle powder and a second insulating layer having an Si-based organic compound sticking on or covering the first insulating layer. The dust core is formed by compacting the soft magnetic material. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention provides a dust core made of a soft magnetic material that does not deteriorate the volume resistivity or strength of the dust core even when annealed at a high temperature to release strain generated during compression molding.

  In recent years, with energy saving and miniaturization of home appliances, electronic devices, and automobiles, there is an increasing demand for miniaturization, high output, and high power conversion efficiency for magnetic core materials used for these. Higher operating frequency is known to be effective in reducing the size of equipment, increasing output, and increasing power conversion efficiency. Even in the high frequency range, high magnetic flux density, magnetic permeability, and low iron loss. There is a strong need for magnetic core materials.

  Conventionally, laminated magnetic cores using silicon steel sheets have been used as such magnetic core materials. However, laminated magnetic cores have a drawback that eddy current loss generated inside the magnetic core increases as the operating frequency increases. have.

  For this reason, in recent years, iron-based metal soft magnetic powder, which has low iron loss in the high-frequency region and superior in three-dimensional formability compared to laminated magnetic cores, is covered with an insulating resin such as phenol resin or epoxy resin and compressed. A dust core made of a molded composite material is widely used as an alternative to a laminated core.

  On the other hand, further miniaturization and higher performance, that is, higher magnetic flux density is desired for the powder magnetic core. For such higher magnetic flux density, the packing density of the soft magnetic powder is increased. Things have been done.

  However, since compression molding is performed at such a high pressure that plastic deformation of the metal powder occurs in order to highly fill the soft magnetic powder, it is known that the soft magnetic powder remains strained and increases hysteresis loss. . Therefore, in order to reduce hysteresis loss due to strain, the molded product is usually annealed.

  By the way, in general, hysteresis loss and eddy current loss are known as main causes of iron loss of a dust core. As described above, it is known that the removal of strain by annealing is effective as a method for reducing hysteresis loss. On the other hand, as a method for reducing eddy current loss, particles are insulated with an insulating resin or the like.

  In general, annealing is considered to be effective at a temperature of 500 ° C. or higher, preferably 600 ° C. or higher. However, when a binding resin as a binder of soft magnetic particle powder or an insulating resin is used for insulation between the above particles, strength deterioration such that when the annealing is performed at a high temperature, the resin decomposes and the molded body becomes brittle. In addition, since the insulating property is lowered, annealing at a high temperature becomes difficult. Therefore, it has been difficult to reduce both hysteresis loss and eddy current loss at the same time with resins that have been studied in the past.

  Up to now, the surface of soft magnetic metal powder is a soft magnetic metal powder (Patent Document 1) in which a phosphate film and a polyimide resin film are formed, or the magnetic powder surface is coated with polyimide resin or polytetrafluoroethylene resin. A technique using magnetic powder (Patent Document 2) as a powder for a powder magnetic core is disclosed.

  Moreover, the technique which uses the iron-type powder coat | covered with the film containing an epoxy resin and an alumina containing silica as powder for powder magnetic cores is disclosed (patent document 3).

  Moreover, the powder magnetic core which combined the iron powder which gave the iron powder or the phosphate compound film on the surface with resin was disclosed (patent document 4).

  Further, a dust core having an insulating layer containing a silicone skeleton and a pigment between magnetic powder particles is disclosed (Patent Document 5).

  Further, it is disclosed that the surface of the soft magnetic powder is coated with a silicone resin and then coated with a higher fatty acid lubricant (Patent Document 6).

  On the other hand, it is preferable that the volume resistivity of the dust core is high. If the volume resistivity of the dust core is high, the permeability hardly changes even in a high frequency range, but if the volume resistivity is low, the frequency is high. In the region, the magnetic permeability tends to decrease rapidly.

  As means for increasing the volume resistivity, soft magnetic powders in which a soft magnetic metal powder is subjected to a phosphate treatment to form a phosphate coating are disclosed (Patent Documents 7 to 8).

JP 2005-317937 A JP 2004-146804 A JP 2003-166004 A JP 2002-246219 A JP 2002-343657 A JP 2000-223308 A JP-A-62-222410 JP-A-63-70504

  Even when annealed at a high temperature, a dust core soft magnetic material having a small change in volume resistivity and a small decrease in strength is currently most demanded, but has not yet been obtained.

  That is, in Patent Documents 1 and 2, a soft magnetic metal powder magnetic powder in which a phosphate film and a polyimide resin film or a polytetrafluoroethylene resin film are formed on the surface of the soft magnetic metal powder is compacted. It is described that it is used as a magnetic core powder. The maximum possible annealing temperature is 550 ° C.

  Patent Document 3 describes that an iron-based powder coated with a coating containing an epoxy resin and alumina-containing silica is used as a powder for a powder magnetic core, and Patent Document 4 describes iron powder or phosphorus. Although the powder magnetic core which combined the iron powder which gave the acid compound film on the surface with the resin is described, the rate of change of the volume resistivity value before and after annealing of the pressure-molded body is 10 to 94%, both It is expensive.

  Patent Document 5 describes a dust core having an insulating layer containing a silicone skeleton and a pigment between magnetic powder particles. However, since a silicone resin is used for the insulating layer, depending on the pressure, Compressed. For this reason, the rate of change in compression density showing compressibility is high, and distortion of the magnetic particles tends to remain during pressure molding.

  Patent Document 6 describes that a soft magnetic particle powder is coated with a silicone resin, but the resin used in the examples does not have a carbon-carbon multiple bond and is resistant to heat. It is difficult to obtain an excellent soft magnetic material.

  Patent Documents 7 to 8 describe amorphous magnetic alloy powders in which a phosphate coating such as zinc phosphate, magnesium phosphate, calcium phosphate, and iron phosphate is formed. The heat resistance temperature that can be processed for annealing is about 500 ° C., and if the salt coating is annealed at a temperature higher than that, it is difficult to maintain the insulating properties.

  Therefore, the present invention has as a technical problem to obtain a soft magnetic material capable of obtaining a dust core with little change in volume resistivity and lowering of strength even when annealed at a high temperature of 700 ° C.

  As a result of intensive studies to solve the above problems, the present inventors formed a first insulating layer made of an inorganic compound on the particle surface of the soft magnetic particle powder, and the surface of the first insulating layer was heat resistant. Is a soft magnetic material composed of a composite particle powder formed with a second insulating layer composed of an extremely high Si-based organic compound, and the volume resistivity even when the dust core obtained by the soft magnetic material is annealed at a high temperature It has been found that there is little change in the value and strength and has a high volume resistivity, and the present invention has been made.

  That is, the present invention has a first insulating layer in which an inorganic compound is attached or coated on the surface of soft magnetic particle powder, and a Si-based organic compound is attached or coated on the surface of the first insulating layer. A soft magnetic material comprising a composite particle powder having a second insulating layer, wherein the Si-based organic compound contains a Si-H bond and a carbon-carbon multiple bond in the molecule. It is a magnetic material (Invention 1).

  In the present invention, the inorganic compound forming the first insulating layer on the particle surface of the soft magnetic particle powder is one selected from aluminum, silicon, calcium, zirconium, titanium, magnesium, zinc, iron, or phosphorus. Or a soft magnetic material according to the first aspect of the present invention, comprising a compound containing two or more elements (the second aspect of the present invention).

  The present invention also includes a step of forming a first insulating layer while adding and mixing a solution of an inorganic compound in a suspension in which soft magnetic particle powder is dispersed in an organic solvent, and forming the first insulating layer. The present invention is characterized in that the second insulating layer is formed while mixing the soft magnetic particle powder and the Si-based organic compound solution dissolved in a predetermined amount of organic solvent, and then dried at 60 to 120 ° C. A method for producing a soft magnetic material according to any one of Invention 1 and Invention 2 (Invention 3).

  Moreover, this invention is a powder magnetic core formed by compression-molding the soft magnetic material according to any one of the present invention 1 or the present invention 2 (Invention 4).

  The soft magnetic material according to the present invention is suitable as a soft magnetic material for a dust core because the powder magnetic core obtained by using the soft magnetic material has little change in volume resistivity and strength even when annealed at a high temperature of 700 ° C. It is.

  By using the soft magnetic material, the dust core according to the present invention has a high volume resistivity and excellent strength, and even when annealed at a high temperature of 700 ° C., the volume resistivity and strength are high. Since the change is small, it is also suitable as a high-performance dust core used at high frequencies.

  The configuration of the present invention will be described in more detail as follows.

  First, the soft magnetic material according to the present invention will be described.

  The soft magnetic material according to the present invention has a first insulating layer to which an inorganic compound is attached or coated on the particle surface of the soft magnetic particle powder, and the Si-based organic compound is attached to or coated on the first insulating layer. The composite particle powder having the second insulating layer.

  The inorganic compound that forms the first insulating layer on the particle surface of the soft magnetic particle powder according to the present invention is not particularly limited as long as it is generally used. When considering the heat resistance of the soft magnetic particle powder and the binding property with the Si-based organic compound, one or more kinds selected from aluminum, silicon, calcium, zirconium, titanium, magnesium, zinc, iron, or phosphorus are used. It is preferable to consist of a compound containing an element.

  The total coating amount of the inorganic compound forming the first insulating layer of the soft magnetic material according to the present invention is preferably 0.001 to 10% by weight in terms of each element. When the amount is less than 0.001% by weight, the effect of the present invention cannot be obtained. Since the effect of the present invention can be sufficiently obtained by the addition amount of 0.001 to 10% by weight, it is meaningless to add more than 10% by weight more than necessary. In consideration of the volume resistivity and strength of the dust core obtained by using the soft magnetic material according to the present invention, it is more preferably 0.010 to 5% by weight, still more preferably 0.050 to 2% by weight. It is.

  The Si-based organic compound forming the second insulating layer on the particle surface of the soft magnetic particle powder according to the present invention contains Si—H bonds and carbon-carbon multiple bonds in the molecule.

  The coating amount of the Si-based organic compound forming the second insulating layer of the soft magnetic material according to the present invention is preferably 0.01 to 30% by weight in terms of C. If it is less than 0.01% by weight, the effect of the present invention cannot be obtained. Since the effect of the present invention can be sufficiently obtained by the addition amount of 0.01 to 30% by weight, it is meaningless to add more than necessary beyond 30% by weight. When considering the volume resistivity of the dust core obtained using the soft magnetic material according to the present invention, and the strength, the coating amount of the Si-based organic compound is more preferably 0.02 to 20% by weight in terms of C, Even more preferably, it is 0.05 to 8% by weight.

  Next, a method for producing a soft magnetic material according to the present invention will be described.

  The soft magnetic material according to the present invention forms a first insulating layer while adding a solution of an inorganic compound to a suspension obtained by dispersing soft magnetic particle powder, which is a particle powder to be processed, in an organic solvent, and rotating and mixing the solution. 60-120 after performing the process and the process of forming the 2nd insulating layer, adding the Si type organic compound solution dissolved in the organic solvent to the soft-magnetic particle powder which formed this 1st insulating layer, and carrying out rotation mixing. It can be obtained by drying at ° C.

  As the soft magnetic particle powder in the present invention, iron powder, silicon steel powder, sendust powder, permalloy powder, permender powder and the like by various production methods such as atomized iron powder, reduced iron powder, and carbonyl iron powder can be used. Considering the magnetic flux density of the obtained dust core, iron powder and permender powder are preferable. The average particle size of the soft magnetic particle powder is preferably 1.0 to 500.0 μm, more preferably 2.0 to 400.0 μm, and still more preferably 3.0 to 300.0 μm.

  Any organic solvent may be used as long as it is generally used, and it is not particularly limited. Specifically, alcohol solvents such as ethyl alcohol, propyl alcohol or butyl alcohol, ketone solvents such as acetone or methyl ethyl ketone, aromatic solvents such as benzene, toluene, xylene, phenol and benzoic acid, and ether solvents such as tetrahydrofuran Solvent, glycol ether solvent such as methyl cellosolve, ethyl cellosolve, propyl cellosolve or butyl cellosolve, oxyethylene such as diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol or tripropylene glycol, polypropylene glycol, oxypropylene addition polymer, ethylene Alkylene glycol such as glycol, propylene glycol or 1,2,6-hexanetriol, glycerin, N-methyl pyridine Etc. can be suitably used pyrrolidone. A preferable solvent in the step of forming the first insulating layer of the soft magnetic particle powder with the solution of the inorganic compound is a water-soluble organic solvent, such as an alcohol solvent such as ethyl alcohol, propyl alcohol, or butyl alcohol, acetone, methyl ethyl ketone, or the like. It is a ketone solvent. A preferable solvent in the step of forming the second insulating layer of the soft magnetic particle powder with the Si-based organic compound solution is an organic solvent such as benzene, toluene, tetrahydrofuran, or N-methylpyrrolidone.

  As the inorganic compound used when forming the first insulating layer of the soft magnetic material according to the present invention, any inorganic compound may be used as long as it is generally used. In order to reduce impurities in the insulating layer, it is preferable to use a metal alkoxide.

  As the metal element constituting the metal alkoxide used in the present invention, aluminum, zirconium, titanium, silicon, magnesium, iron, vanadium, germanium, tantalum, tungsten, indium, molybdenum, barium and the like can be used, preferably aluminum, Silicon, calcium, zirconium, titanium, magnesium, zinc and iron. Moreover, as a kind of alkoxide, methoxide, ethoxide, propoxide, isopropoxide, oxyisopropoxide, butoxide, etc. can be used. In consideration of the uniformity of the treatment and the effect of the present invention, aluminum triisopropoxide, tetraethoxysilane, calcium diethoxide, zirconium tetraisopropoxide, titanium tetraisopropoxide and the like are preferable.

  The metal alkoxide is preferably used after being dispersed or dissolved in advance in the above-mentioned organic solvent in order to perform a more uniform treatment.

  In addition, the hydrolysis of the metal alkoxide does not require any particular addition of water in order to attach or cover a finer inorganic compound to the particle surface of the soft magnetic particles. It is preferable to perform hydrolysis with moisture.

  The addition amount of the metal alkoxide varies depending on the specific surface area of the soft magnetic particle powder, but is usually 0.001 to 100 parts by weight in terms of each element per 100 parts by weight of the soft magnetic particle powder. When the amount is less than 0.001 part by weight, the effect of the present invention cannot be obtained. Since the effect of this invention is fully acquired by the addition amount of 0.001-100 weight part, it is meaningless to add more than necessary exceeding 100 weight part. In consideration of the volume resistivity value and strength of the dust core obtained by using the soft magnetic material according to the present invention, 0.002 to 75 parts by weight is preferable, and 0.005 to 50 parts by weight is more preferable. .

  In the present invention, a phosphoric acid solution or a phosphate solution may be added instead of the metal alkoxide. More preferably, the phosphoric acid solution or the phosphate solution is added to the suspension to which the metal alkoxide solution is added.

  The phosphoric acid used in the present invention is an acid formed by hydrating diphosphorus pentoxide, and metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, triphosphoric acid, and tetraphosphoric acid can be used, preferably orthophosphoric acid. is there.

  The amount of phosphoric acid or phosphate added in the present invention varies depending on the specific surface area of the soft magnetic particle powder, but is usually 0.001 to 100 parts by weight in terms of P per 100 parts by weight of the soft magnetic particle powder. When the amount is less than 0.001 part by weight, the effect of the present invention cannot be obtained. Since the effect of this invention is fully acquired by the addition amount of 0.001-100 weight part, it is meaningless to add more than necessary exceeding 100 weight part. In consideration of the volume resistivity value and strength of the dust core obtained by using the soft magnetic material according to the present invention, 0.002 to 75 parts by weight is preferable, and 0.005 to 50 parts by weight is more preferable. .

  When adding phosphoric acid or phosphate as an aqueous solution, it is preferable to add a small amount in order to prevent hydrolysis from proceeding rapidly.

  The equipment for mixing the soft magnetic particle powder and the metal alkoxide solution and / or phosphoric acid or phosphate solution includes a high-speed agitate mixer, specifically a Henschel mixer, a speed mixer, a ball cutter, a power mixer, A hybrid mixer or the like may be used.

The Si-based organic compound used when forming the second insulating layer of the soft magnetic material according to the present invention has at least one Si—H bond and at least one carbon-carbon multiple bond in the repeating unit. It is a polymer, and this repeating part occupies at least 1/3 or more of the entire polymer.
Examples of the carbon-carbon multiple bond include —C≡C— and —C═C—, and —C≡C— is more preferable.

  Specific examples may be compounds having repeating units represented by the following chemical formulas 1 to 5. (Itoh M. et al., Polym. Sci. Part A: Polym. Chem. 39, 2658-2669 (2001); ) -Based Polymers Containing Hydrophilic Groups and Unsufficient Carbon-Carbon Bonds. ", Processeds of the 5th European Technical Symptom s Montpellier (France), 3May 1999, Poreddy Narsi Roddy et al., Chemistry Letters, 254 (2000), Yamashita H.and Uchimaru Y.Chem.Commun., 1763 (1999)

Here, in the formula, R, R ¹ , R ² and R ³ are each independently selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, an alkynyl group, an aromatic group such as a phenyl group and a naphthyl group. Group. These groups may contain a substituent selected from a halogen atom, a hydroxyl group, an amino group, and a carboxyl group. X and y are both positive integers, and x / y is preferably in the range of 0.01 to 100, more preferably 0.1 to 10.

That is, as a more specific example of the Si-based organic compound, the repeating unit is poly (methylsilyleneethynylene-1,4-phenyleneethynylene), poly (methylsilinyleneethynylene-1,2-phenyleneethylene). Nylene), poly (methylsilyleneethynylene-1,3-phenyleneethynylene) (see Formula 6), poly (phenylsilyleneethynylene-1,3-phenyleneethynylene) (see Formula 7),
Poly (phenylsilyleneethynylene-1,2-phenyleneethynylene), poly (phenylsilyleneethynylene-1,4-phenyleneethynylene),
Poly (phenylsilyleneethynylene-1,2,3-phenyleneethynylene), poly (silyleneethynylene-1,4-phenyleneethynylene), poly (silyleneethynylene-1,2-phenyleneethynylene), poly ( Silyleneethynylene-1,3-phenyleneethynylene) (see Chemical Formula 8),
Poly (silylene ethynylene),
Poly (phenylsilyleneethynylene-1,2-phenyleneethynylene), poly (hexylsilyleneethynylene-1,3-phenyleneethynylene), poly (vinylsilyleneethynylene-1,3-phenyleneethynylene),
Poly (phenylsilyleneethynylene-1,4-phenyleneoxy-1 ′, 4′-phenyleneethynylene) (see Chemical Formula 9),
Moreover, the conventionally well-known thing etc. which are the compounds shown to Chemical formula 10-Chemical formula 13 etc. are mentioned.

  In addition, although there is no restriction | limiting in particular about a weight average molecular weight, Preferably it is 500-500000. The form of these Si-based organic compounds is solid or liquid at room temperature, and can be used alone or in admixture of two or more.

  Moreover, as a manufacturing method of Si type organic compounds represented by the above chemical formulas 1 to 5, dehydrogenation of a diethynyl compound and a silane compound using a metal compound such as a basic oxide, a metal hydride, or a metal alkoxide as a catalyst. A method for carrying out copolymerization (for example, JP-A-7-090085, JP-A-11-158187), a method for carrying out dehydrogenation polymerization of an ethynylsilane compound using a basic oxide as a catalyst (JP-A-9-143271) ), A method of reacting an organomagnesium reagent and dichlorosilanes (Japanese Patent Laid-Open No. 7-102069), a method of dehydrogenating copolymerization of a diethynyl compound and a silane compound using cuprous chloride and a tertiary amine as a catalyst. (Hua Qin Liu and John F. Harrod, The Canadian Journal of Chem. stry, Vol.68,1100-1105 (1990)) can conventionally known production methods utilizing such, and is not particularly limited.

  The Si-based organic compound is described in detail in JP-A No. 2004-162128.

  The Si-based organic compound is preferably used after being dissolved in the above-mentioned organic solvent such as toluene in order to perform a more uniform film treatment.

  The addition amount of the Si-based organic compound varies depending on the specific surface area of the soft magnetic particle powder, but is usually 0.01 to 50 parts by weight in terms of C per 100 parts by weight of the soft magnetic particle powder. If the amount is less than 0.01 parts by weight, the Si-based organic compound is too small to uniformly coat the surface of the soft magnetic particle powder, and the effect of the present invention cannot be obtained. Since the effect of the present invention is sufficiently obtained by the addition amount of 50 parts by weight, there is no meaning to add more than necessary beyond 50 parts by weight. In consideration of the electric resistance value and strength of the dust core obtained by using the soft magnetic material according to the present invention, 0.02 to 30 parts by weight is preferable, and 0.05 to 10 parts by weight is more preferable.

  As a device for mixing the soft magnetic particle powder and the Si-based organic compound solution, a general-purpose mixer, specifically a Henschel mixer, a universal stirrer, a hybrid mixer, or the like may be used.

  When the Si-based organic compound solution is added to the soft magnetic particle powder, it is preferable to add the Si-based organic compound solution by a small amount by spraying while rotating and mixing the soft magnetic particle powder for uniform adhesion.

  The obtained soft magnetic particle powder can be obtained by drying in a draft at room temperature for 3 to 24 hours and then drying in a temperature range of 60 to 120 ° C. for 1 to 24 hours.

  Next, the dust core according to the present invention will be described.

  The powder magnetic core according to the present invention is obtained by mixing the soft magnetic material according to the present invention with an additive such as a lubricant such as zinc stearate, if necessary, and compression-molding the mixed particle powder, followed by heat treatment. Can be obtained by:

  The compression molding can be performed by a compression molding method using a mold that is usually performed. In addition, what is necessary is just to select a shaping | molding pressure suitably according to a use.

  The annealing temperature for strain relief after compression molding is desirably a high temperature at which the magnetic particles themselves do not cause particle growth due to thermal diffusion. In this examination, 600 degreeC and 700 degreeC were employ | adopted as temperature which the Si type organic compound used accept | permitted.

  The volume resistivity of the dust core according to the present invention is preferably 200 mΩ · cm or more, more preferably 300 mΩ · cm or more at room temperature. The volume resistivity value after heating at 700 ° C. for 60 minutes in an inert gas atmosphere such as nitrogen or Ar gas is preferably 400 mΩ · cm or more. That is, it is not preferable that the volume specific resistance value of the dust core is easily lowered by annealing.

  The strength of the powder magnetic core according to the present invention is preferably 15 MPa or more, more preferably 20 MPa or more at room temperature. The strength of the dust core after annealing (treatment in an inert gas such as nitrogen gas or Ar gas at 700 ° C. for 60 minutes) is preferably 30 MPa or more. That is, it is necessary to ensure the strength without reducing the strength of the dust core.

<Action>
The most important point in the present invention is that the surface of the soft magnetic particle powder has a first insulating layer on which an inorganic compound is attached or coated, and the surface of the first insulating layer is attached or covered with a Si-based organic compound. The fact that the dust core formed by using the soft magnetic material composed of the composite particle powder having the second insulating layer is not reduced in volume resistivity or strength even when annealed at a high temperature.

  The reason why the heat resistance of the soft magnetic material according to the present invention is excellent is that the surface of the soft magnetic material has a first coating layer made of a heat-resistant inorganic compound, and a second coating layer is formed. Since Si-based organic compounds have carbon-carbon multiple bonds and Si-H bonds in the molecule, it is estimated to be a composite inorganic material consisting of SiC fine particles and amorphous carbon as the heat treatment temperature rises. doing.

  It is a fact that the dust core obtained by using the soft magnetic material according to the present invention has a high volume resistivity.

  The reason why the dust core according to the present invention has a high volume resistivity value is that an inorganic compound having excellent insulating properties and a Si-based organic compound are used for the insulating coating material.

  Further, as a reason why the volume specific resistance value and strength of the powder magnetic core obtained by using the soft magnetic material according to the present invention do not decrease even when annealed at a high temperature, the present inventor By having the first coating layer made of a compound, the hydroxyl group on the surface of the soft magnetic material is increased, and the Si-based organic compound having excellent heat resistance and strength that forms the second coating layer is more uniformly and firmly coated. It is presumed that it is highly related to this.

  Hereinafter, the present invention will be described in detail with reference to examples.

  The average particle diameter of each particle powder was measured by measuring the particle diameter of 350 particles shown in the transmission electron micrograph, and the average value was shown.

  The amount of the element (Si, Al, P, Ca, Ti) in the insulating layer adhered or coated on the particle surface of the soft magnetic particle powder is “X-ray fluorescence analyzer 3063M type” (manufactured by Rigaku Corporation) ) In accordance with JIS K0119 “General Rules for Fluorescence X-ray Analysis”.

  The amount of Si-based organic compound coated on the surface of the soft magnetic particle powder should be measured using a “Horiba Metal Carbon / Sulfur Analyzer EMIA-2200 Model” (manufactured by Horiba, Ltd.). Determined by

  In order to measure the volume resistivity value and strength of the powder magnetic core obtained by using the soft magnetic particle powder, 6.0 g of the soft magnetic particle powder was first measured and coated with zinc stearate having an outer diameter of 20 mm and an inner diameter of 10 mm. Using a ring molding die, pressure molding was performed at a molding pressure of 686 MPa with a 10-ton press to produce a plurality of ring molded bodies.

  The volume resistivity of the powder magnetic core obtained using the soft magnetic particle powder is 10 V on the press surface of the ring molded body by a 4-terminal electrical resistance measuring device (Loresta GP / MCP-T600, manufactured by Mitsubishi Kasei) with a pitch of 1 mm. The voltage was applied and measured.

The volume specific resistance value at each heat treatment temperature of the powder magnetic core obtained using the soft magnetic particle powder is 600, respectively, in an N ₂ atmosphere using an atmosphere adjustment heat treatment furnace for the two produced ring molded bodies. Using the ring molded body after heat treatment for 1 hour at a temperature of 700 ° C., the volume specific resistance value was determined by the method described above.

  As an evaluation of the strength of the powder magnetic core obtained using the soft magnetic particle powder, the above-described ring molded body was produced in the same manner, and the crushing strength was measured based on the JIS Z 2507 rule. The measurement of the crushing strength was obtained from the pressure at the time of fracture occurrence using a compression tester (Digital Force Gauge / ZP-500N, manufactured by Imada Seisakusho) with the ring molded body standing. An average value obtained from 10 ring molded bodies in consideration of variation was collected.

The strength at each heat treatment temperature of the dust core is 10 ring molded bodies after heat treatment at 600 and 700 ° C. for 1 hour in an N ₂ atmosphere using an atmosphere adjustment heat treatment furnace. Thus, it was determined by the method for measuring the crushing strength described above.

<Example 1: Production of soft magnetic material>
Acetone solution in which 180 g of tetraethoxysilane is dispersed is added to 10 kg of particle 1 (iron powder, particle shape: granular, average particle diameter 115 μm, water atomized powder), and then mixed while rotating using a mixer. 100 g of an aqueous phosphoric acid solution (phosphoric acid content: 85% by weight) was dropped into the solution, and the mixture was stirred and mixed for 20 minutes at a reaction temperature of 45 ° C. in a N ₂ stream.

  The obtained mixed solution was dried under reduced pressure at 45 ° C. to obtain particles 4 that are soft magnetic materials coated with an inorganic compound containing silicon and phosphorus. The surface treated product adhering to or covering the particles 4 was 0.24% by weight in terms of Si and 0.26% by weight in terms of P.

Next, after adding a toluene solution in which 200 g of Si-based organic compound, which is poly (phenylsilyleneethynylene-1,3-phenyleneethynylene), is added to 10 kg of particles 4, while rotating and mixing using a mixer, The mixture was stirred and mixed for 20 minutes at a reaction temperature of 45 ° C. under a N ₂ stream.

  The obtained mixed solution was dried under reduced pressure at 45 ° C., and the obtained soft magnetic particle powder coated with the Si-based organic compound was dried at 80 ° C. for about 12 hours using a ventilating drier. Example 1) was obtained. The Si-based organic compound adhering to or covering the obtained soft magnetic material (Example 1) was 0.93% by weight in terms of C.

<Manufacture of dust core>
6.0 g of the obtained soft magnetic material (Example 1) was weighed and compression-molded into a ring shape (φ20 × φ10 mm) at a molding pressure of 686 MPa using a die coated with zinc stearate. Molded body) was obtained. The ring molded body had a volume specific resistance value (25 ° C.) of 309 mΩ · cm and a crushing strength value (25 ° C.) of 35 MPa.

  The volume resistivity value before and after the heat treatment was measured as the heat resistance evaluation of the powder magnetic core (ring molded body) produced above, and the pressure ring strength value was measured as the strength evaluation. The heat treatment was performed at 600 and 700 ° C. for 60 minutes in nitrogen gas.

  The volume specific resistance values after heat treatment at 600 ° C. and 700 ° C. of the ring molded body produced above were 412 mΩ · cm and 515 mΩ · cm, respectively. Further, the crushing strength values after heat treatment at 600 and 700 ° C. of the ring molded body were 78 MPa and 97 MPa, respectively.

  In the same manner as in Example 1, a soft magnetic material and a dust core were produced. Various characteristics of each manufacturing condition, the obtained soft magnetic material, and the dust core are shown.

Soft magnetic material: particles 2-3
A soft magnetic particle powder having the characteristics shown in Table 1 was prepared as a particle to be treated.

Surface-treated soft magnetic particle powder: particles 5 to 7
A first coated surface-treated soft magnetic particle powder was obtained in the same manner as the particles 4 except that the type of soft magnetic particle powder, the type of surface treatment agent in the surface treatment step, and the amount added were variously changed.

  Table 2 shows the production conditions and various properties of the obtained soft magnetic particle powder.

Surface-treated soft magnetic particle powder: Examples 2 to 4
A soft magnetic material for a dust core and a dust core were obtained in the same manner as in Example 1 except that the type and addition amount of the Si-based organic compound were variously changed.

  Table 3 shows the manufacturing conditions at this time, and various properties of the obtained soft magnetic material for the dust core and the dust core.

Surface-treated soft magnetic particle powder: Comparative Example 1
The particles 1 were not treated with an inorganic compound or Si-based organic compound.

Surface-treated soft magnetic particle powder: Comparative Example 2
The inorganic compound treatment was not performed on the particles 1, and only the Si-based organic compound treatment was performed.

Surface-treated soft magnetic particle powder: Comparative Example 3
The surface treatment of the polyimide which is known to be excellent in heat resistance described in Patent Documents 1 and 2 was performed on the particles 4 subjected to the inorganic compound treatment on the particles 1.

  Table 3 shows the production conditions of Comparative Examples 1 to 3, and the characteristics of the obtained soft magnetic particle powder and the dust core.

  Even when the soft magnetic material according to the present invention is annealed at a high temperature of 700 ° C. sufficient to eliminate the distortion of the dust core during compression molding, there is little change in the electrical resistance value or strength of the dust core. It is suitable as a soft magnetic material for a powder magnetic core.

By using the soft magnetic material, the dust core according to the present invention has a higher volume resistivity and strength, and even when annealed at a high temperature of 700 ° C., the volume resistivity and strength. Therefore, it is suitable as a high-performance dust core used at a high frequency.

Claims (4)

The first insulating layer has an inorganic compound adhered or coated on the surface of the soft magnetic particle powder, and the second insulating layer has an Si-based organic compound adhered or coated on the surface of the first insulating layer. A soft magnetic material comprising a composite particle powder, wherein the Si-based organic compound contains a Si-H bond and a carbon-carbon multiple bond in a molecule. The inorganic compound forming the first insulating layer on the particle surface of the soft magnetic particle powder is one or more elements selected from aluminum, silicon, calcium, zirconium, titanium, magnesium, zinc, iron or phosphorus. The soft magnetic material according to claim 1, comprising a compound to be contained. A step of adding and mixing a solution of an inorganic compound in a suspension in which soft magnetic particle powder is dispersed in an organic solvent to form a first insulating layer; a soft magnetic particle powder having the first insulating layer formed; After performing the step of forming the second insulating layer while mixing with an organic solvent in which a Si-based organic compound having a Si—H bond and a carbon-carbon multiple bond in the molecule is dissolved, drying at 60 to 120 ° C. The method for producing a soft magnetic material according to claim 1, wherein: A dust core formed by compression-molding the soft magnetic material according to claim 1.