Soft magnetic resin composition and molded article using same

Abstract

According to the present embodiment, it is possible to provide a soft magnetic resin composition capable of forming a molded article having excellent physical properties such as heat resistance, bending strength, IZOD impact strength, and the like without deteriorating magnetic properties, and having reduced generation of corrosive gas. A soft magnetic resin composition and a molded article thereof, the soft magnetic resin composition comprising a soft magnetic metal powder, a PPS resin, and a hydrotalcite powder, the content of the hydrotalcite powder being 0.1-15.0 wt% with respect to the PPS resin.

Description

Technical Field

[0001] The present disclosure relates to a soft magnetic resin composition that exhibits excellent physical properties such as heat resistance, flexural strength, and IZOD impact strength without degrading electromagnetic properties, and reduces the generation of corrosive gases. The present disclosure also relates to a molded article using the soft magnetic resin composition. Background Art

[0002] In recent years, with the increasing electrification of automobiles, demands have arisen for automotive components to be high-frequency, compact, lightweight, and fuel-efficient. Currently, soft magnetic materials such as electromagnetic steel sheets and pressed powder cores are primarily used for automotive components (rotors, stators, and other motor components; inductors, transformers, reactors, and other choke coils; and current sensors). From the perspective of further miniaturization, high frequency, and greater molding flexibility, there is a desire to replace these soft magnetic materials with molded articles made from soft magnetic resin compositions.

[0003] Generally, a soft magnetic resin composition is prepared by kneading a rubber or plastic material with a soft magnetic powder, and then molding the mixture into a desired shape using a molding machine such as an injection molding machine.

[0004] Automobile parts are strongly required to have high heat resistance and mechanical strength. Therefore, when using a resin composition, PPS resin is used as a binder resin because it is considered to have high heat resistance and little deterioration in mechanical properties at high temperatures.

[0005] However, in the injection molding of the resin composition using the PPS resin, the corrosive gas (Cl - or SO4 2- ) may increase the number of mold maintenance times during production, shorten the mold life, and deteriorate the molded body of the soft magnetic resin composition due to rusting of the soft magnetic metal powder. Therefore, there is a strong demand for reducing corrosive gases.

[0006] Furthermore, when used in an AC magnetic field, soft magnetic materials are required to have low iron loss characteristics in addition to high magnetic permeability and high saturation magnetization. However, the soft magnetic metal powder contained in the soft magnetic resin composition may deteriorate due to surface oxidation.

[0007] For example, Patent Documents 1 and 2 describe that deterioration of electromagnetic properties and rusting can be suppressed by using a resin composition using a surface-treated soft magnetic metal powder.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 7-235410

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2021-121004 Summary of the Invention

[0012] However, no countermeasures have been taken against rusting of the molding die or the soft magnetic metal powder caused by the corrosive gas from the PPS resin.

[0013] Therefore, the present disclosure sets as a technical object to obtain a soft magnetic resin composition that is excellent in physical properties such as heat resistance, flexural strength, and IZOD impact strength without degrading electromagnetic properties and reduces the generation of corrosive gas, and a molded article using the same.

[0014] The above technical problems can be achieved by the following present embodiment.

[0015] That is, the soft magnetic resin composition of the first embodiment includes soft magnetic metal powder, PPS resin, and hydrotalcite powder, and contains 0.1 to 15.0% by weight of hydrotalcite based on the PPS resin.

[0016] The soft magnetic resin composition of the second embodiment is the soft magnetic resin composition of the first embodiment containing 1.0 to 15.0% by weight of a PPS resin.

[0017] The soft magnetic resin composition of the third embodiment is the soft magnetic resin composition of the first or second embodiment containing 0.001 to 4.0% by weight of hydrotalcite.

[0018] The soft magnetic resin composition of the fourth embodiment is the soft magnetic resin composition of the first to third embodiments in which the hydrotalcite powder is Mg—Al-based hydrotalcite.

[0019] The molded article of the fifth embodiment is a molded article obtained by molding the soft magnetic resin composition of any one of the first to fourth embodiments.

[0020] According to this embodiment, it is possible to avoid reducing J s (saturation magnetization), reduce the generation of corrosive gases. And, the molded article that uses the soft magnetic resin composition of present embodiment to obtain has physical properties such as high flexural strength and high IZOD impact strength. Therefore, this resin combination is suitable for the injection molding of automobile parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a graph showing the effect of suppressing the weight increase caused by rusting of the metal rod due to corrosive gas.

[0022] Figure 2This is a graph showing the effect of suppressing the weight increase due to rust of a soft magnetic resin composition molded article (magnetic core) caused by corrosive gas. DETAILED DESCRIPTION

[0023] Hereinafter, this embodiment will be described in detail.

[0024] The soft magnetic resin composition of the present embodiment contains at least soft magnetic metal powder, PPS resin, and hydrotalcite powder.

[0025] The soft magnetic metal powder used in this embodiment is not particularly limited, and any soft magnetic metal powder commonly used in resin compositions can be used, such as FeSi-based, FeSiCr, FeSiAl, and carbonyl iron powder.

[0026] The average particle size of the soft magnetic metal powder is preferably 1.0 to 100.0 μm, more preferably 10.0 to 90.0 μm, and preferably spherical in terms of filling properties and fluidity.

[0027] The soft magnetic metal powder is preferably subjected to various surface treatments in order to prevent deterioration of magnetic properties due to oxidation and to improve compatibility with resins and the strength of molded articles.

[0028] Examples of materials that can be surface treated include silane coupling agents, titanium coupling agents, aluminum coupling agents, siloxane polymers, organic phosphoric acid surface treatment agents, inorganic phosphoric acid surface treatment agents, etc. In particular, by pre-treating the surface of the soft magnetic metal powder with a silane coupling agent, the strength of the molded article can be further improved.

[0029] The hydrotalcite powder used in this embodiment is of the general formula: [M 2+ 1-x M 3+ x (OH)2][A n- x / n ·mH2O](where M 2+ Mg 2+ 、Co 2+ 、Ni 2+ 、Zn 2+ Equivalent metal ions. M 3+ Al 3+ 、Fe 3+ Cr 3+ Etc. trivalent metal ions. n- Indicates OH - 、Cl - 、CO3 2- 、SO4 2-A layered compound represented by (a) anion and an interlayer anion. x satisfies 0<x<1. n is the valence of A. m satisfies 0≤m<1).

[0030] The hydrotalcite powder used in this embodiment preferably contains Mg 2+ As a divalent metal ion, containing Al 3+ Mg-Al based hydrotalcites as trivalent metal ions. Some or all of these metal ions may be substituted with other metal ions.

[0031] The hydrotalcite powder used in this embodiment comprises plate-like particles. The average plate diameter is 0.01 to 1.0 μm, preferably 0.02 to 0.8 μm, and more preferably 0.03 to 0.7 μm. If the average plate diameter is less than 0.01 μm, dispersibility in the resin is insufficient. If the average plate diameter exceeds 1.0 μm, industrial production of plate-like particles is difficult.

[0032] The BET specific surface area of ​​the hydrotalcite powder used in this embodiment is preferably 1 to 150 m 2 / g, more preferably 5 to 100 m 2 / g, more preferably 8 to 50 m 2 / g. With less than 1m 2 It is difficult to obtain hydrotalcite particles with a BET specific surface area of ​​more than 150 m / g in industry. 2 When the particle size is less than 100 μg, the particles aggregate violently, and as a result, it becomes difficult to uniformly disperse the particles in the resin.

[0033] The hydrotalcite powder used in this embodiment may be coated with a surface treatment agent selected from at least one of higher fatty acids, anionic surfactants, higher fatty acid phosphates, coupling agents, and polyol esters, as needed. The surface treatment agent improves the dispersibility of the hydrotalcite powder in the resin.

[0034] The hydrotalcite powder used in this embodiment can be produced by conventional methods. For example, the following method can be used: first, a mixture prepared by mixing a magnesium compound and an aluminum compound is calcined, and then the resulting Mg-Al composite oxide is hydrated with an aqueous solution containing anions. Alternatively, in another example, the hydrotalcite powder can be obtained by adding an aqueous solution of a calcium salt to a mixed aqueous solution prepared by mixing an alkaline aqueous solution containing anions, an aqueous solution of a magnesium salt, and an aqueous solution of an aluminum salt, and then heating and aging the resulting aqueous solution containing the calcium salt.

[0035] The PPS resin used in this embodiment is not particularly limited, but preferably has an average molecular weight of 10,000 to 100,000. When a low-molecular-weight PPS resin is used, its relatively low melt viscosity results in excellent moldability of the injection molding composition, but physical properties such as strength may be poor. Conversely, when a high-molecular-weight PPS resin is used, its relatively high melt viscosity results in excellent physical properties, but moldability may be poor if the soft magnetic metal powder loading is high.

[0036] The melt viscosity of the PPS resin can be appropriately adjusted depending on the soft magnetic metal powder. The preferred melt viscosity is 5 to 200 Pa·s at 310°C. If the melt viscosity at 310°C is less than 5 Pa·s, the mechanical strength of the resulting soft magnetic resin composition may be reduced. On the other hand, if the melt viscosity at 310°C exceeds 200 Pa·s, the fluidity of the soft magnetic resin composition is significantly reduced, making injection molding difficult.

[0037] There are no particular restrictions on the molecular structure of the PPS resin. Specifically, its molecular structure can be, for example, either a cross-linked or linear structure. Furthermore, the PPS resin can be compounded with various elastomers such as rubber or elastic resins as needed.

[0038] The soft magnetic resin composition of this embodiment contains hydrotalcite powder at a content of 0.1 to 15.0% by weight relative to the PPS resin. If the hydrotalcite content is less than 0.1% by weight relative to the PPS resin, the effect of reducing corrosive gases is insufficient. If the hydrotalcite content exceeds 15.0% by weight relative to the PPS resin, mechanical properties, magnetic properties, and fluidity are reduced. The hydrotalcite content is more preferably 0.5 to 13.0% by weight relative to the PPS resin, and even more preferably 1.0 to 10.0% by weight.

[0039] The soft magnetic resin composition of this embodiment preferably contains 0.001 to 4.0% by weight of hydrotalcite powder. If the content of hydrotalcite powder is less than 0.001% by weight, the effect of reducing corrosive gases is insufficient. If the content of hydrotalcite powder exceeds 4.0% by weight, the non-magnetic component increases. As a result, mechanical properties, magnetic characteristics, and fluidity may be reduced. The content of hydrotalcite powder is preferably 0.005 to 3.5% by weight, and more preferably 0.01 to 3.0% by weight.

[0040] The soft magnetic resin composition of this embodiment preferably contains 1.0 to 15.0% by weight of PPS resin. If the PPS resin content is less than 1% by weight, the soft magnetic resin composition may not have sufficient fluidity. In this case, it is difficult to obtain a good molded product. If the PPS resin content exceeds 15% by weight, the electromagnetic properties may be reduced. The PPS resin content is more preferably 2.0 to 12.0% by weight, and even more preferably 3.0 to 10.0% by weight.

[0041] The content of the soft magnetic metal powder in the soft magnetic resin composition of this embodiment is preferably 82.0 to 98.5% by weight. If the content of the soft magnetic metal powder is less than 82.0% by weight, the desired magnetic properties may not be obtained. If the content of the soft magnetic metal powder exceeds 98.5% by weight, the mechanical strength of the resulting molded body may be reduced, and the moldability such as fluidity and reusability may be extremely reduced. The content of the soft magnetic metal powder is more preferably 85.0 to 97.0% by weight, and even more preferably 90.0 to 95.0% by weight.

[0042] Next, a method for producing the soft magnetic resin composition according to the present embodiment will be described.

[0043] The soft magnetic resin composition of the present embodiment can be obtained by a known method for producing a soft magnetic resin composition. For example, first, a soft magnetic metal powder, a PPS resin component, and a hydrotalcite powder are uniformly mixed and then melt-kneaded using a mixing extruder or the like. The resulting mixture is then crushed or cut into granular or particulate forms to obtain a soft magnetic resin composition.

[0044] The soft magnetic resin composition of the present embodiment may appropriately contain a lubricant for plastic molding, various stabilizers, and the like in order to achieve effects such as improved moldability, improved heat resistance, and prevention of oxidative degradation and rust.

[0045] Examples of lubricants include saturated and unsaturated fatty acids such as propionic acid, stearic acid, linoleic acid, oleic acid, malonic acid, glutaric acid, adipic acid, maleic acid, and fumaric acid, and their derivatives. Examples of derivatives include metal soaps such as calcium stearate, magnesium stearate, and lithium stearate; and fatty acid amides such as hydroxystearic acid amide, ethylenebislauric acid amide, and ethylenebisoleic acid amide. Other examples include waxes such as paraffin, polysiloxanes such as dimethylpolysiloxane and silicone oil, and fluorine compounds such as fluorine-containing oils.

[0046] To suppress thermal degradation, it is preferable to add an antioxidant as a stabilizer. Examples of antioxidants include hindered amine stabilizers. Other examples include hindered / lowly hindered phenol-based antioxidants such as pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; metal deactivators such as N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionylhydrazine]; and antioxidants such as phosphite and thioether. The combined use of hindered / lowly hindered phenol-based antioxidants and phosphite antioxidants or metal deactivators is particularly effective.

[0047] The antioxidant is contained in an amount of preferably 0.1 to 1.0 wt%, more preferably 0.2 to 0.8 wt%, based on the total amount of the resin composition.

[0048] Furthermore, a known mold release agent such as zinc stearate or calcium stearate may be added to the resin as needed.

[0049] Furthermore, in order to improve the impact resistance and the like, a known resin modifier such as silicone rubber, acrylic rubber, or butadiene rubber may be added to the resin as needed.

[0050] The molding method for obtaining the molded product using the soft magnetic resin composition of this embodiment is not particularly limited. Depending on the material properties, molding purpose and use of the soft magnetic resin composition, any of the known methods such as transfer molding, injection molding, extrusion, expansion molding, calendering, T-die method, blow molding, vacuum method, lamination, injection molding, foaming, die-to-die molding and SMC method can be utilized. In addition, among these methods, multiple methods can also be combined for use. In particular, the preferred molding method for the soft magnetic resin composition using PPS resin as a thermoplastic resin is injection molding or extrusion. These molding methods can be applied to most industrial components. In addition, through these molding methods, continuous high-speed and large-scale production can be achieved.

[0051] Example

[0052] Representative examples of the present embodiment are shown below, but the present embodiment is not limited to these examples.

[0053] The average plate surface diameter of the hydrotalcite powder is determined based on the transmission electron microscope photograph of the observation sample. The average value of the measured values ​​is defined as the average plate surface diameter of the hydrotalcite powder. The transmission electron microscope used is "JEM-1200EXII (manufactured by JEOL)". A solution containing hydrotalcite powder dispersed in water or alcohol is injected onto a sieve. The observation sample is prepared by drying the particles attached to the sieve. Within the observation sample, particles (200 points) whose plate surfaces are horizontally attached to the sieve are selected. The plate surface diameter of the selected particles is measured.

[0054] The BET specific surface area value of the hydrotalcite powder was measured using "Monosorb MS-21 (manufactured by QUANTA CHROME)".

[0055] The mold density of the soft magnetic resin composition was determined using an "Electronic Density Meter EW-120SG" (manufactured by Yasuda Seiki Co., Ltd.). Specifically, the density of a magnetic core obtained by molding the melted soft magnetic resin composition in a mold with a diameter of 25 mm and a height of 10.5 mm was measured using the electronic density meter.

[0056] Magnetic properties of soft magnetic resin compositions (saturation magnetization J s ) was determined using the following method. First, a soft magnetic resin composition melted in a 25 mm diameter, 10.5 mm high mold was molded to produce a magnetic core. The magnetic properties of the resulting core were measured using a "DC Magnetization Characteristics Automatic Recorder 3257" (manufactured by Yokogawa Hokushin Electric Co., Ltd.) in a magnetic field of 1114.1 kA / m (14 kOe).

[0057] About the amplitude permeability μ a and iron loss P cv The soft magnetic resin composition was injection molded using a J55AD injection molding machine manufactured by Japan Steel Works, Ltd. to obtain a toroidal core with an outer diameter of φ32mm, an inner diameter of φ19mm, and a height of 7mm. The amplitude permeability μ of the obtained toroidal core is a and iron loss P cv The measurement was performed using a BH analyzer SY-8218 manufactured by Iwasaki Communication Equipment Co., Ltd. under the conditions of Bm=50 mT and 10 kHz.

[0058] The soft magnetic resin composition was injection molded using a J55AD injection molding machine manufactured by Nippon Steel Works, Ltd., to produce a molded article for strength testing with a total length of 80 mm, a total width of 12.7 mm, and a thickness of 3.2 mm. The injection moldability of the soft magnetic resin composition was determined based on the injection pressure recorded during injection molding of the test piece.

[0059] The flexural strength and IZOD impact strength of the molded articles used in the strength test using the soft magnetic resin composition were measured in accordance with ASTM D790 and D256. More specifically, the molded articles were produced using a J55AD injection molding machine manufactured by Japan Steel Works, Ltd. The flexural strength and IZOD impact strength of the molded articles were then measured using a computer-controlled precision universal testing machine AG-1 manufactured by Shimadzu Corporation and a No. 158 manufactured by Yasuda Seiki Seisakusho Co., Ltd.

[0060] Example 1

[0061] 0.28 parts by weight of aminoalkyl silane coupling agent was added to 92.7 parts by weight of Fe6.5Si powder (average particle size D50 = 75 μm). The mixture was heated and mixed at 120°C until the resulting mixture became uniform. In this way, a surface-treated powder was obtained. 6.4 parts by weight of PPS resin (average molecular weight: 41,000, melt viscosity: 60 Pa·s at 310°C) and Mg-Al hydrotalcite powder (average plate diameter: 0.24 μm, BET value: 11 m 2 The obtained mixture was thoroughly mixed with a Henschel mixer to obtain a mixture of a soft magnetic resin composition.

[0062] The resulting soft magnetic resin composition mixture was quantitatively fed into a twin-shaft kneader and kneaded at a temperature at which the PPS resin melted. The kneaded product was cut into pellets. Thus, a soft magnetic resin composition was obtained.

[0063] Table 1 shows the composition, molding density, and electromagnetic properties of the obtained soft magnetic resin composition.

[0064] Table 2 shows the results of measuring the injection pressure during injection molding of the soft magnetic resin composition and the flexural strength and IZOD impact strength of the molded article for a strength test obtained by the injection molding.

[0065] Examples 2 to 4, Comparative Examples 1 to 2

[0066] Soft magnetic resin compositions were prepared in the same manner as in Example 1 except that the blending ratios of the soft magnetic powder, PPS resin, and hydrotalcite powder were variously changed as shown in Table 1.

[0067] [Table 1]

[0068]

[0069] [Table 2]

[0070]

[0071] The rusting of the metal rod caused by the corrosive gas was evaluated as follows. 20 g of particles obtained by pre-drying the particles of the soft magnetic resin composition (140°C×3hr) were put into a test tube. The metal rod passed through the open rubber plug, and the test tube was sealed with the rubber plug. The test tube was heated at 350°C×3hr in a solder bath (POT-28C) manufactured by Dayang Electric Industry Co., Ltd. At this time, the corrosive gas generated by the particles in the test tube adhered to the metal rod. Then, the metal rod was taken out of the test tube and exposed to the conditions of 23°C×95%RH for 16 days using a constant temperature and humidity controller LH-114 manufactured by ESPEC Co., Ltd. The weight increase caused by the rusting of the metal rod was calculated by subtracting the weight before exposure from the weight after exposure. The results are recorded in Tables 3 and Figure 1 .

[0072] [Table 3]

[0073]

[0074] Can confirm that along with the increase of the addition amount of hydrotalcite, the weight gain of metal bar reduces. In addition, also can find out from the outward appearance of metal bar that by adding hydrotalcite, can suppress rust. That is, the soft magnetic resin composition of present embodiment is compared with the soft magnetic resin composition of comparative example 1 that does not contain hydrotalcite powder, can confirm the effect of suppressing the corrosion of peripheral metal. Should explain, can see that the intensity of the flexural strength and IZOD impact strength of the molded body of the soft magnetic resin composition of comparative example 2 reduces.

[0075] The rusting of the soft magnetic metal powder in the molded article caused by corrosive gas was evaluated as follows. A magnetic core formed by melting the soft magnetic resin composition in a mold with a diameter of 25 mm and a height of 10.5 mm was exposed to the conditions of temperature: 85°C and humidity: 90% RH for 1000 hours using a thermohygrostat LH-114 manufactured by ESPEC Co., Ltd. The weight increase of the magnetic core was calculated by subtracting the weight before exposure from the weight after exposure. The results are recorded in Tables 4 and Figure 2 .

[0076] [Table 4]

[0077]

[0078] Can confirm that along with the increase of the addition amount of hydrotalcite, the weight gain of magnetic core reduces.In addition, also can find out from the outward appearance of magnetic core that by adding hydrotalcite, can suppress rusting.That is, used the molded body of the soft magnetic resin composition of present embodiment owing to containing hydrotalcite, can suppress the deterioration caused by the rusting of the soft magnetic metal powder in the molded body.

[0079] Industrial applicability

[0080] Therefore, the use of the soft magnetic resin composition of this embodiment can provide a molded article that maintains high electromagnetic and mechanical properties while reducing the generation of corrosive gas. Therefore, the soft magnetic resin composition is suitable as a soft magnetic resin composition for automobile parts, for example.

Claims

1. A soft magnetic resin composition, The invention comprises soft magnetic metal powder, PPS resin and hydrotalcite powder, wherein the hydrotalcite is contained in an amount of 0.1 to 15.0 wt % based on the PPS resin.

2. The soft magnetic resin composition according to claim 1, wherein Contains 1.0 to 15.0% by weight of PPS resin.

3. The soft magnetic resin composition according to claim 1 or 2, wherein Contains 0.001 to 4.0% by weight of hydrotalcite.

4. The soft magnetic resin composition according to claim 1 or 2, wherein The hydrotalcite powder is Mg-Al hydrotalcite. 5 . A molded body obtained by molding the soft magnetic resin composition according to claim 1 .

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