Composition and injection molded article

Abstract

To provide: a composition capable of giving a molded article that is suitable for injection molding and has satisfactory magnetic properties; and an injection-molded article having satisfactory magnetic properties.SOLUTION: A composition contains magnetic particles and a thermoplastic resin. At least some of the magnetic particles are provided with coating layers.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a composition and an injection molded article. [Background technology]

[0002] Compacts made of compositions containing a binder and magnetic powder are known as magnetic cores for various magnetic elements such as choke coils and inductors. A widely known method for producing such compacts is a pressure molding method using a thermosetting resin as a binder (see, for example, Patent Document 1). Furthermore, as magnetic powders with excellent magnetic properties, Patent Documents 2 to 4 disclose Fe-based nanocrystalline alloys having magnetic properties such as low coercive force, low magnetostriction, high magnetic permeability, and high saturation magnetic flux density.

[0003] On the other hand, Patent Document 5 discloses a method of injection molding a composition containing a thermoplastic resin and magnetic powder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-10426 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-12699 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-150665 [Patent Document 4] International Publication No. 2011 / 24580 [Patent Document 5] Japanese Patent Application Publication No. 2019-102713 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, when a compact is manufactured by pressure molding using the above-mentioned magnetic powder of the Fe-based nanocrystalline alloy, the core loss (iron loss) may become larger than designed. After extensive research, the present inventors have found that distortion may occur in the magnetic powder during pressure molding.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a composition that is suitable for injection molding and from which a molded article having excellent magnetic properties can be obtained, and an injection molded article having excellent magnetic properties. [Means for solving the problem]

[0007] The composition according to the present invention contains a magnetic powder and a thermoplastic resin, At least a portion of the magnetic powder has a coating layer.

[0008] In the composition, the coating layer may contain one or more selected from glass, silicone resin, and coupling agents.

[0009] In the composition, the coating layer may contain one or more selected from glass, silicone resin, and coupling agents.

[0010] In the composition, the coating layer may contain one or more materials selected from glass and silicone resin.

[0011] In the composition, the coating layer may contain a coupling agent.

[0012] In the composition, the coating layer may have a first layer containing one or more selected from glass and silicone resin, and a second layer containing a coupling agent.

[0013] In the composition, the magnetic powder may contain an Fe-based nanocrystalline alloy.

[0014] In the composition, the magnetic powder may contain an Fe—Si alloy.

[0015] The composition may be such that the magnetic powder includes a first magnetic powder having a median diameter of 1 to 50 μm and a second magnetic powder having a median diameter of 10 to 300 μm, and the median diameter of the second magnetic powder is larger than the median diameter of the first magnetic powder.

[0016] In the composition, the first magnetic powder may be an Fe-based nanocrystalline alloy, and the second magnetic powder may be an Fe—Si alloy.

[0017] In the composition, the mass ratio of the first magnetic powder to the second magnetic powder may be 95:5 to 50:50.

[0018] In the composition, the glass may include a phosphate glass.

[0019] The composition may have a melt flow rate at 330°C of 80 g / 10 min or more.

[0020] The composition may be used in injection molding.

[0021] The injection-molded article according to the present invention is an injection-molded article made from the composition according to the present invention.

[0022] The core loss of the above injection molded body measured under the conditions of a frequency of 20 kHz and an applied magnetic flux density of 100 mT was 350 kW / m 3 It may be the following:

[0023] The core loss of the above injection molded body measured under the conditions of a frequency of 100 kHz and an applied magnetic flux density of 100 mT was 2800 kW / m 3 It may be the following:

[0024] The injection molded article may have a magnetic permeability retention rate of 83% or more at a frequency of 100 kHz and a magnetic field strength of 8 kA / m.

[0025] The injection molded article may have a radial crushing strength of 40 MPa or more.

[0026] The injection molded article has a resistance of 1×10 13 It may be Ω or more. [Effects of the Invention]

[0027] The present invention provides a composition that is suitable for injection molding and that can give a molded article having excellent magnetic properties, and an injection molded article having excellent magnetic properties. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a magnetic powder having a coating layer. [Figure 2] FIG. 10 is a schematic cross-sectional view showing another example of magnetic powder having a coating layer. [Figure 3] FIG. 1 is a schematic cross-sectional view showing an example of an injection-molded body. [Figure 4] 1 is a cross-sectional SEM image of the injection-molded article of Example 1. [Figure 5] 1 is a cross-sectional SEM image of the injection-molded article of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been simplified as appropriate, and the scale of each element in the drawings may differ significantly for illustrative purposes. Furthermore, unless otherwise specified, the symbol "to" indicating a range of values ​​includes the lower and upper limits.

[0030] [Composition] The composition according to the present invention is characterized by containing a magnetic powder and a thermoplastic resin, and having a coating layer on at least a portion of the magnetic powder. The use of magnetic powder having a coating layer in the composition improves the fluidity of the composition when the thermoplastic resin is heated above its melting point. This makes the composition suitable for injection molding. Because a molded body can be formed by injection molding, the problem of magnetic powder distortion that can occur during pressure molding does not occur, resulting in a molded body with excellent magnetic properties. Furthermore, the use of magnetic powder having a coating layer improves the adhesion between the magnetic powder and the thermoplastic resin, thereby improving the mechanical strength of the molded body, such as its radial crushing strength.

[0031] The composition contains at least a magnetic powder having a coating layer and a thermoplastic resin, and may further contain other components as long as the effects of the present invention are achieved. Each component will be described below.

[0032] <Magnetic powder> The magnetic powder can be appropriately selected from known magnetic powders used for cores of magnetic elements according to the required magnetic properties, etc. From the viewpoint of magnetic properties, soft magnetic powder is preferred, and soft magnetic powder containing iron (Fe) as the main component (50 at% or more) is preferred.

[0033] The magnetic powder may be composed of iron alone or may be an alloy containing iron and other elements, such as boron (B), nitrogen (N), carbon (C), oxygen (O), phosphorus (P), silicon (Si), nickel (Ni), chromium (Cr), aluminum (Al), copper (Cu), titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W), chromium (Cr), cobalt (Co), manganese (Mn), silver (Ag), zinc (Zn), tin (Sn), arsenic (As), antimony (Sb), bismuth (Bi), yttrium (Y), and rare earth elements such as samarium (Sm).

[0034] Specific examples of soft magnetic powders include carbonyl iron, Fe-Si alloys, Fe-Ni alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-based amorphous alloy powders containing at least Fe-B, and Fe-based nanocrystalline alloys containing at least Fe-BP-Cu. The Fe-based amorphous alloys are amorphous alloys that do not have a crystalline structure. The Fe-based nanocrystalline alloys are alloys obtained by heat-treating the Fe-based amorphous alloys to precipitate fine α-Fe crystals in the amorphous phase. The magnetic powders can be used singly or in combination of two or more types. The magnetic powder in this composition preferably contains an Fe-based nanocrystalline alloy and / or an Fe-Si alloy, and more preferably an Fe-based nanocrystalline alloy. The Fe-based nanocrystalline alloy reduces magnetocrystalline anisotropy due to the presence of highly magnetized α-Fe phase as fine nanocrystals, and reduces magnetostriction due to the mixed phase of positive magnetostriction of the amorphous phase and negative magnetostriction of the α-Fe phase, resulting in good magnetic properties such as high saturation magnetic flux density (Bs) and low loss.

[0035] (Fe-based nanocrystalline alloy) The Fe-based nanocrystalline alloy preferably contains at least Fe, B, P, and Cu. From the viewpoints of magnetic properties and ease of production, the Fe-based nanocrystalline alloy preferably has a composition that satisfies the following formula (1) or (2): B, P, Si, and C are elements that contribute to the formation of an amorphous phase, and Cu is an element that contributes to nanocrystallization. Fe w B x P y Cu z ···(1) Fe a B b Si c P d C e Cu f ···(2) In formula (1), w is 76 to 88 at%, x is 4 to 13 at%, y is 1 to 10 at%, z is 0.5 to 1.5 at%, and w+x+y+z is 100 at%, In formula (2), a is 76 to 88 at%, b is 4 to 13 at%, c is 0 to 8 at%, d is 0.1 to 10, e is 0 to 5 at%, f is 0.4 to 1.4 at%, and a+b+c+d+e+f is 100 at%.

[0036] The above formulas (1) and (2) may contain other elements such as Ti, Zr, Hf, Nb, Ta, Mo, W, Cr, Co, Ni, Al, Mn, Ag, Zn, Sn, As, Sb, Bi, Y, N, O, S, and rare earth elements in an amount of 3 at% or less of the total composition. In this case, w in formula (1) and a in formula (2) represent the total content of iron and the other elements.

[0037] The shape of the Fe-based nanocrystalline alloy is preferably spherical in terms of magnetic properties, injection moldability, and ease of alloy production. In this embodiment, spherical means that the aspect ratio of the alloy observed in a cross-sectional SEM (scanning electron microscope) image of the injection-molded article is 1 to 3, and preferably 1 to 2. The median diameter (D50) of the Fe-based nanocrystalline alloy is preferably 1 to 50 μm from the viewpoints of magnetic properties, injection moldability, and ease of manufacturing the alloy. In this embodiment, the median diameter is a value calculated from the particle size distribution measured by laser diffraction.

[0038] The Fe-based nanocrystalline alloy can be produced by, for example, referring to JP 2012-12699 A, JP 2010-150665 A, WO 2011 / 24580, etc. Specifically, the alloy can be produced by preparing an alloy composition that satisfies the above formula (1) or (2) and has an amorphous phase as the main phase, forming it into powder by atomization or the like, and then heat-treating it at a predetermined temperature. According to the above method, spherical particles with a median diameter of 1 to 50 μm can be obtained.

[0039] (Fe-Si alloy) The magnetic powder is preferably an Fe-Si alloy, either alone or in combination with the Fe-based nanocrystalline alloy, which allows for injection-molded articles with relatively high magnetic permeability and low loss. The content of Si in the Fe—Si alloy is preferably 2 to 10 mass %, more preferably 3 to 7 mass %, based on the total amount of the Fe—Si alloy. The Fe-Si alloy may further contain other elements such as Cr, Al, Mn, Ni, C, O, N, S, P, B, and Cu. The content of these other elements is preferably 3% by mass or less, and more preferably 1% by mass or less, based on the total amount of the Fe-Si alloy.

[0040] The Fe-Si alloy preferably has a spherical shape in terms of magnetic properties and injection moldability. The median diameter (D50) of the Fe—Si alloy is preferably 1 to 500 μm in terms of magnetic properties and injection moldability.

[0041] The Fe—Si alloy can be obtained by preparing an alloy having the above composition and powdering it by atomization, etc. Alternatively, a commercially available product having the desired composition and particle size may be used.

[0042] In this embodiment, the magnetic powder may be a combination of a first magnetic powder having a median diameter of 1 to 50 μm and a second magnetic powder having a median diameter of 10 to 300 μm, preferably 60 to 300 μm. By combining a second magnetic powder having a larger median diameter than the first magnetic powder, a composition with excellent fluidity and injection moldability can be obtained even when the composition contains a high proportion of magnetic powder. When the first magnetic powder and the second magnetic powder are combined, the proportion of magnetic powder in the composition can be 70 to 85% by volume, preferably 70 to 80% by volume. Furthermore, the ratio of the median diameter d502 of the second magnetic powder to the median diameter d501 of the first magnetic powder (d502 / d501) is preferably 1.5 or more. When d502 / d501 is 1.5 or more, the fluidity of the composition is likely to be further improved.

[0043] In this case, from the viewpoint of ease of production, the first magnetic powder is preferably an Fe-based nanocrystalline alloy, and the second magnetic powder is preferably an Fe—Si alloy. Furthermore, the mass ratio of the first magnetic powder to the second magnetic powder is preferably 95:5 to 50:50, more preferably 80:20 to 70:30, from the viewpoint of magnetic properties and fluidity.

[0044] On the other hand, when the ratio of magnetic powder in the composition is less than 70% by volume, it is preferable to use the Fe-based nanocrystalline alloy alone in terms of magnetic properties and the like.

[0045] When using an Fe-based nanocrystalline alloy alone, the ratio of magnetic powder in the composition is preferably 60 to 70 volume % relative to 100 volume % of the composition, more preferably 62 to 68 volume %, in order to achieve both injection moldability and magnetic properties.

[0046] <Coating layer> In this embodiment, the magnetic powder has a coating layer on at least a portion thereof. FIGS. 1 and 2 are schematic cross-sectional views showing an example of a magnetic powder 100 having a coating layer. As in the example of FIGS. 1 and 2, a coating layer 20 is formed on the surface of the magnetic powder 10. As in the example of FIG. 1, the coating layer 20 may be a single layer, or as in FIG. 2, the coating layer 20 may have a laminated structure of two or more layers having a first layer 1 and a second layer 2. The coating layer 20 may also be a single layer containing two or more components. The coating layer 20 may cover the entire surface of the magnetic powder, or may have intermittent portions.

[0047] The material of the coating layer is preferably selected from materials having at least one of the functions of improving fluidity, improving insulation, and improving adhesion to the thermoplastic resin. Specific examples include glass, silicon resin, and coupling agents.

[0048] From the viewpoint of insulation, the coating layer preferably contains glass or silicone resin. By providing a coating layer containing glass or silicone resin, direct contact between magnetic powder particles is suppressed, improving insulation. Examples of glass include silicate glass, borate glass, borosilicate glass, and phosphate glass, among which phosphate glass is preferred. The coating layer containing phosphate glass improves the fluidity of the composition. The phosphate glass may also contain other inorganic oxides such as ZnO, SiO2, Bi2O3, and Al2O3. The coating amount of the glass and silicone resin is preferably 0.3 to 5% by volume, more preferably 0.5 to 3% by volume, relative to 100% by volume of the present composition.

[0049] In order to improve adhesion to the thermoplastic resin and improve the mechanical strength of the injection-molded article, the coating layer preferably contains a coupling agent. Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, and a zirconium coupling agent, and the silane coupling agent is preferred. The organic group of the silane coupling agent may be appropriately selected in consideration of affinity depending on the type of thermoplastic resin. Specific examples of silane coupling agents include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, dimethoxydiphenylsilane, trifluoropropyltrimethoxysilane, n-propyltriethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ureidopropyltrialkoxysilane, 3-isocyanatepropyltriethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, and 3-mercaptopropylmethyldimethoxysilane. These may be used alone or in combination of two or more. The coating amount of the coupling agent is preferably 0.3 to 3% by volume, more preferably 0.5 to 2% by volume, and even more preferably 0.6 to 1.2% by volume, relative to 100% by volume of the present composition.

[0050] From the viewpoints of fluidity, insulation, and improved adhesion to thermoplastic resins, the coating layer preferably has a laminated structure having a first layer containing one or more selected from glass and silicone resin, and a second layer containing a coupling agent, and more preferably the first layer contains glass. In this case, as shown in the example of Figure 2, the layer structure is magnetic powder 10, first layer 1, and second layer 2. The coupling agent in the second layer has excellent adhesion to the glass or silicone resin of the first layer and affinity with the thermoplastic resin, thereby improving adhesion between the magnetic powder and the thermoplastic resin and improving the mechanical strength of the injection-molded body.

[0051] The method for forming the coating layer may be selected appropriately depending on the type of coating material. In the case of a glass agent, a glass layer can be formed on the surface of the magnetic powder by a thin film formation method such as a sol-gel method, or by a method in which a magnetic powder and a glass powder are mixed while applying mechanical stress. In the case of a silicone resin or a coupling agent, a solution or dispersion containing the coating material can be prepared and applied by various coating methods or immersion methods.

[0052] <Thermoplastic resin> The thermoplastic resin can be appropriately selected depending on the injection moldability, heat resistance, mechanical strength, etc. required for the injection molded article. Specific examples of the thermoplastic resin include polyvinyl chloride, polystyrene, acrylonitrile-butadiene-styrene (ABS) resin, polyamide including aromatic polyamide, polyethylene, polypropylene, methacrylic resin, polycarbonate, polyimide, polyamideimide, polyether ether ketone, polyphenylene sulfide, etc., and these can be used alone or in combination of two or more. In this embodiment, from the viewpoint of mechanical strength and the like, the thermoplastic resin preferably contains polyamide, polyphenylene sulfide, or polyether ether ketone, and more preferably contains polyamide.

[0053] The ratio of the thermoplastic resin in the composition is preferably 20 to 40% by volume, more preferably 25 to 35% by volume, and even more preferably 30 to 35% by volume, relative to 100% by volume of the composition, in order to achieve both injection moldability and magnetic properties.

[0054] <Optional ingredients> The composition may further contain other components within the range in which the effects of the present invention are achieved. Examples of other components include stabilizers such as antioxidants, lubricants, UV absorbers, metal deactivators, HALS, and PVC stabilizers, and function-imparting agents such as plasticizers, flame retardants, nucleating agents, fillers, compatibilizers, curing agents, photoinitiators, antistatic agents, anti-fog agents, conductive agents, clarifying agents, lubricants, and antibacterial agents. These may be used alone or in combination of two or more.

[0055] From the viewpoint of injection moldability, the composition preferably has a melt flow rate of 80 g / 10 min or more, more preferably 90 g / 10 min or more, at 330° C. The melt flow rate is measured in accordance with JIS K 7210 using a melt indexer with a die (nozzle) having an inner diameter of 1.05 mm and a length of 4 mm, at a measurement temperature of 330° C. and a test pressure of 20 kg. The melt flow rate of the composition can be adjusted by the type and content of the thermoplastic resin, the particle size and content of the magnetic powder, and the like.

[0056] The method for producing the composition is not particularly limited, and it can be obtained, for example, by adding magnetic powder having a coating layer and each component used as needed to a heated thermoplastic resin and kneading them.

[0057] The present composition has excellent injection moldability due to the combination of magnetic powder having a coating layer and a thermoplastic resin, and is suitable as an injection molding composition for forming cores for various magnetic elements.

[0058] [Injection molded product] The injection-molded article according to the present invention is a molded article obtained by injection molding the composition. Fig. 3 is a schematic cross-sectional view showing an example of this injection-molded article. As shown in the example of Fig. 3, this injection-molded article 200 is molded in a state in which magnetic powder 100 having a coating layer is dispersed in thermoplastic resin 30. This injection-molded article is molded without pressure, and does not suffer from the problem of magnetic powder distortion that can occur during pressure molding, and is a molded article with excellent magnetic properties. The components that can be contained in the injection molded article and the content ratios thereof are the same as those in the above-mentioned composition, and therefore a description thereof will be omitted here.

[0059] The injection molding method is not particularly limited, and for example, an injection-molded article can be obtained by filling a molten thermoplastic resin composition into a mold cavity using a cylinder and cooling it. Also, a molded article with an embedded coil may be formed by referring to JP 2019-102713 A or the like.

[0060] The injection-molded article can be used as a low-loss core. For example, the injection-molded article has a core loss of 350 kW / m, measured under conditions of a frequency of 20 kHz and an applied magnetic flux density of 100 mT. 3 It can achieve 310kW / m 3 Preferably less than 300kW / m 3 The following is more preferred: For example, the core loss of this injection molded product measured under conditions of a frequency of 100 kHz and an applied magnetic flux density of 100 mT is 2800 kW / m 3 It can achieve 2700kW / m 3 Less than 2400kW / m is preferable. 3 The following is more preferred:

[0061] The injection-molded article has excellent DC bias characteristics. For example, the injection-molded article can achieve a magnetic permeability retention rate of 83% or more at a frequency of 100 kHz and a magnetic field strength of 8 kA / m, preferably 83.5% or more, and more preferably 85% or more. The magnetic permeability retention rate is a value calculated from the magnetic permeability μ measured under the condition of a magnetic field strength of 0 and the magnetic permeability μ' measured under the above conditions using the following formula (3): Retention rate (%)=(μ' / μ)×100 (3)

[0062] The injection-molded article has excellent adhesion between the magnetic powder and the thermoplastic resin and high mechanical strength. For example, the injection-molded article can achieve a radial crushing strength of 35 MPa or more, preferably 40 MPa or more, and more preferably 42 MPa or more. In this embodiment, the radial crushing strength is a value determined according to the radial crushing strength testing method of JIS Z2507.

[0063] Furthermore, the injection molded article has excellent insulating properties. For example, the resistance value of the injection molded article is 1×10 13 It is possible to achieve Ω or more.

[0064] The injection-molded article having the above-described properties can be suitably used in any of the conventionally known applications, and can be suitably used, for example, as a magnetic core for various magnetic elements such as choke coils and inductors. [Example]

[0065] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these descriptions.

[0066] Example 1 The magnetic powders prepared were the Fe-based nanocrystalline alloy A described below and an Fe-Si alloy (Si content 6.5 mass%, D50: 150 μm), and each was coated with phosphate glass in an amount of 1.9% by volume relative to 100% by volume of the composition described below to form coating layer 1. Next, 3-aminopropyltriethoxysilane (a silane coupling agent; KBE-903 manufactured by Shin-Etsu Silicones Co., Ltd.) was coated in an amount of 0.6% by volume relative to 100% by volume of the composition described below to form coating layer 2, thereby obtaining magnetic powder with a coating layer. Next, the Fe-based nanocrystalline alloy and the Fe-Si alloy were added to molten aromatic polyamide (thermoplastic resin; PA9T (N1000A) manufactured by Kuraray Co., Ltd.) in a mass ratio of 8:2 to obtain a composition with a magnetic powder ratio of 70% by volume. The composition was injection molded using an injection molding machine (STX-10S2V) manufactured by Nissei Plastics Co., Ltd. to obtain a ring-shaped molded body having an outer diameter of 13 mm and an inner diameter of 8 mm.

[0067] Examples 2 to 14 Molded articles having the above shapes were obtained in the same manner as in Example 1, except that the compositions of the compositions in Example 1 were changed as shown in Tables 1 to 3. In the tables, when coating layer 1 or coating layer 2 is marked with "-", this indicates that neither coating layer 1 nor coating layer 2 was present, and the coating layer was a single layer.

[0068] (Comparative Example 1) A molded article having the above shape was obtained in the same manner as in Example 1, except that the composition of the composition was changed as shown in Table 1.

[0069] (Comparative Example 2) The composition of the composition was changed as shown in Table 3, and instead of injection molding, 5 ton / cm 2 The mixture was subjected to pressure molding at a molding pressure of 1000 kJ / cm 2 , to obtain a molded article having the same shape as in Example 1. The phenol resin is a thermosetting resin.

[0070] The abbreviations in the table regarding the compositions are as follows: Alloy A: Fe-based nanocrystalline alloy A (Fe 84.3 B6P9Cu 0.7 (at%), D50:30μm) Alloy B: Fe-based nanocrystalline alloy B (Fe 84.3 B9P6Cu 0.7 (at%), D50:30μm) Fe-6.5Si:Fe-Si alloy (Si content 6.5% by mass, D50: 150μm) KBE-903: 3-aminopropyltriethoxysilane

[0071] [evaluation] <Melt flow rate MFR> Using a melt indexer (Toyo Seiki Co., Ltd. Melt Indexer (Type C 50590)), the composition before molding was measured for melt flow rate using a die (nozzle) with an inner diameter of 1.05 mm and a length of 4 mm, under conditions of a measurement temperature of 330°C and a test pressure of 20 kg, in accordance with JIS K 7210.

[0072] <density> The density of the molded body was calculated as an apparent density from the volume and weight of the molded body.

[0073] <Ring crushing strength> The compression test of the molded body was carried out using a small tabletop tester (LITTLE SENSTARLS C-02 / 300-2) manufactured by Tokyo Testing Machines Co., Ltd., in accordance with the radial crushing strength test method of JIS Z2507, and the radial crushing strength was calculated and evaluated using formula (4). K = [F × (De)] / (L × e 2 ) :Formula (4) K: Radial crushing strength (MPa) F: Maximum load at break (N) L: Length of hollow cylinder (mm) D: Outer diameter of hollow cylinder (mm) e: Wall thickness of hollow cylinder (mm)

[0074] <Insulation resistance> The insulation resistance of the molded body was measured using a Keysight resistance meter (B2985A) by applying a voltage of 100 V to electrodes with a diameter of 1 mm placed on the top and bottom surfaces of the molded body.

[0075] <Saturation magnetization Js> The calculation was made from the BH curve obtained using a BH analyzer (BH5501) manufactured by Denshi Jiku Kogyosha.

[0076] <Magnetic permeability μ, μ', and retention rate Δμ> The magnetic permeability was measured by winding 10 turns of copper wire around a ring-shaped molded body having an outer diameter of 13 mm and an inner diameter of 8 mm, and measuring the magnetic permeability μ and μ' using an HP LCR meter (4284A) under the conditions of a frequency of 100 kHz, a magnetic field strength of 0, and a magnetic field strength of 8 kA / m, and then calculating the retention rate Δμ based on the above formula (3).

[0077] <Core Loss Pcv> Core loss was measured using an Iwasaki BH analyzer (SY8219) under the following two conditions. These are designated Pcv1 and Pcv2, respectively. (1) Frequency: 20 kHz, applied magnetic flux density: 100 mT (2) Frequency: 100 kHz, applied magnetic flux density: 100 mT The evaluation results are shown in Tables 1 to 3.

[0078] [Table 1]

[0079] [Table 2]

[0080] [Table 3]

[0081] The molded body of Example 1 was also cut, and the cut surface was observed using an SEM. The SEM images are shown in Figures 4 and 5. As shown in Figure 5, the molded body of Example 1 has excellent wettability of the thermoplastic resin to the coating layer, and the coating layer and the thermoplastic resin are in close contact with each other. As shown in Figure 4, although small gaps are sometimes observed between the magnetic powder and the thermoplastic resin in the molded body of Example 1, they are generally in close contact with each other, and it is estimated that their strength will be improved. The composition and molded article of Comparative Example 1, which used magnetic powder having no coating layer, were inferior to those of the Examples in terms of melt flow rate, insulation resistance, DC bias characteristics, and core loss. In Comparative Example 2, in which pressure molding was performed using a thermosetting resin, it was shown that the core loss was particularly large even though the magnetic powder was the same as in Example 1. This was presumed to be due to distortion of the magnetic powder during pressure molding. The molded article of Example 4, which used magnetic powder having a coating layer of a silane coupling agent, was shown to be superior to Comparative Example 1, particularly in terms of radial crushing strength and suppression of core loss. Furthermore, the molded body of Example 3, which used magnetic powder having a coating layer of phosphate glass, was shown to be superior to Comparative Example 1 in terms of particularly improved melt flow rate and suppression of core loss. The molded bodies of Examples 1 to 2 and Examples 5 to 15, which were injection molded using a composition containing a magnetic powder with two coating layers and a thermoplastic resin, were shown to have excellent performance in terms of radial crushing strength, insulation resistance, DC bias characteristics, and core loss. In this way, the injection molded article of this embodiment can be suitably used as a magnetic core for various magnetic elements such as choke coils and inductors. [Explanation of symbols]

[0082] 1 1st layer (covering layer), 2 2nd layer (covering layer), 10 magnetic powder, 20 coating layer, 30 thermoplastic resin, 100 Magnetic powder with coating layer, 200 Injection molded body.

Claims

1. Contains magnetic powder and thermoplastic resin, The magnetic powder contains an Fe-based nanocrystalline alloy having a composition that satisfies the following formula (1) or (2): At least a portion of the magnetic powder has a coating layer, The composition, wherein the coating layer comprises one or more selected from glass, silicone resin, and coupling agents. Fe ｗ B ｘ P ｙ Cổ ｚ ・・・(1) ｦe ａ B ｂ ｳi ｃ P ｄ 3 ｅ Cu ｆ ・・・(2) In formula (1), w is 76 to 88 at%, x is 4 to 13 at%, y is 1 to 10 at%, z is 0.5 to 1.5 at%, and w+x+y+z is 100 at%, In formula (2), a is 76 to 88 at%, b is 4 to 13 at%, c is 0 to 8 at%, d is 0.1 to 10, e is 0 to 5 at%, f is 0.4 to 1.4 at%, and a+b+c+d+e+f is 100 at%.

2. The composition of claim 1 , wherein the coating layer comprises one or more selected from glass and silicone resin.

3. The composition of claim 1 , wherein the coating layer comprises a coupling agent.

4. The composition according to any one of claims 1 to 3, wherein the coating layer has a first layer containing one or more selected from glass and silicone resin, and a second layer containing a coupling agent.

5. The composition according to any one of claims 1 to 4, wherein the magnetic powder further comprises an Fe-Si alloy.

6. The composition according to any one of claims 1 to 5, wherein the magnetic powder comprises a first magnetic powder having a median diameter of 1 to 50 μm and a second magnetic powder having a median diameter of 10 to 300 μm, and the median diameter of the second magnetic powder is larger than the median diameter of the first magnetic powder.

7. 7. The composition of claim 6, wherein the first magnetic powder is an Fe-based nanocrystalline alloy and the second magnetic powder is an Fe-Si alloy.

8. 8. The composition according to claim 6, wherein the ratio of the first magnetic powder to the second magnetic powder is 95:5 to 50:50 by mass.

9. The composition of any one of claims 1 to 8, wherein the glass comprises a phosphate glass.

10. The composition according to any one of claims 1 to 9, having a melt flow rate at 330°C of 80 g / 10 min or more.

11. The composition according to any one of claims 1 to 10, which is for injection molding.

12. An injection molded article of the composition according to any one of claims 1 to 11.

13. The core loss measured under the conditions of a frequency of 20 kHz and an applied magnetic flux density of 100 mT was 350 kW / m ３ 13. The injection molded body according to claim 12, wherein:

14. The core loss measured under the conditions of a frequency of 100 kHz and an applied magnetic flux density of 100 mT was 2800 kW / m ３ 14. The injection-molded article according to claim 12 or 13, wherein:

15. The injection molded article according to any one of claims 12 to 14, wherein the retention rate of magnetic permeability is 83% or more at a frequency of 100 kHz and a magnetic field strength of 8 kA / m.

16. The injection molded article according to any one of claims 12 to 15, having a radial crushing strength of 40 MPa or more.

17. Resistance is 1 x 10 １３ The injection molded article according to any one of claims 12 to 16, having a modulus of elasticity of Ω or more.

Images