Resin composition and reactor

Abstract

This resin composition includes a base resin, an inorganic filler, and a rubber filler. The base resin and the rubber filler satisfy a first condition and / or a second condition. The first condition is that the tensile elastic modulus of the base resin is 3 GPa or less. The second condition is that the glass transition temperature of the rubber filler is -40°C or less.

Description

Resin composition and reactor

[0001] This disclosure relates to resin compositions and reactors. This application claims priority under Japanese Patent Application No. 2025-031476 dated 28 February 2025, incorporating by reference all the provisions of the said Japanese application.

[0002] Patent documents 1 and 2 disclose a resin composition comprising a resin and an inorganic filler. This resin composition has high thermal conductivity due to the inclusion of the inorganic filler. The inorganic filler consists of at least one selected from the group consisting of metal carbides, metal oxides, and metal nitrides.

[0003] Japanese Patent Publication No. 2024-149637, International Publication No. 2023 / 182395

[0004] The resin composition of this disclosure comprises a base resin, an inorganic filler, and a rubber filler. The base resin and the rubber filler satisfy at least one of a first condition and a second condition. The first condition is that the tensile modulus of the base resin is 3 GPa or less. The second condition is that the glass transition temperature of the rubber filler is -40°C or less.

[0005] Figure 1 is a cross-sectional view of a resin composition according to an embodiment. Figure 2 is a schematic perspective view of a reactor according to an embodiment, seen from diagonally above. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 2. Figure 5 is a schematic configuration diagram showing the power supply system of a hybrid vehicle. Figure 6 is a circuit diagram showing an example of a power conversion device equipped with a converter.

[0006] Molded resin compositions may develop cracks. Residual stress may be generated in the resin composition during molding. If this residual stress is high, cracks are more likely to occur. In addition, if the resin composition is exposed to a low-temperature environment, cracks may occur due to thermal shock. In particular, resin compositions containing inorganic fillers are prone to cracking because their tensile modulus is high.

[0007] One of the objectives of this disclosure is to provide a resin composition that is less prone to cracking.

[0008] The resin composition of this disclosure is less prone to cracking.

[0009] First, the embodiments of this disclosure will be listed and described.

[0010] (1) A resin composition according to an embodiment of the present disclosure comprises a base resin, an inorganic filler, and a rubber filler. The base resin and the rubber filler satisfy at least one of a first condition and a second condition. The first condition is that the tensile modulus of the base resin is 3 GPa or less. The second condition is that the glass transition temperature of the rubber filler is -40°C or less.

[0011] The resin composition described in (1) above can alleviate residual stress generated in the resin composition by including a rubber filler. Furthermore, the resin composition described in (1) above has a low tensile modulus by satisfying at least one of the first and second conditions. Therefore, the resin composition described in (1) above is less prone to cracking.

[0012] Furthermore, the resin composition described in (1) above has high thermal conductivity due to the inclusion of an inorganic filler.

[0013] (2) In the resin composition of (1) above, the rubber filler is made of rubber that satisfies the second condition above, and the material of the rubber filler may be butadiene rubber.

[0014] By using butadiene rubber as the rubber filler material, the tensile modulus of the resin composition can be effectively lowered.

[0015] (3) In the resin composition of (1) or (2) above, the base resin is made of a resin that satisfies the first condition, and the material of the base resin may be a polyamide resin.

[0016] By using a polyamide resin as the base resin material, the tensile modulus of the resin composition can be effectively lowered.

[0017] (4) In any of the resin compositions described in (1) to (3) above, the content of the rubber filler may be 1% by volume or more and 6% by volume or less.

[0018] By having a rubber filler content within the above range, it is easier to lower the tensile modulus of the resin composition.

[0019] (5) In any of the resin compositions described in (1) to (4) above, the content of the inorganic filler may be 20% by volume or more and 75% by volume or less.

[0020] Having an inorganic filler content within the above range makes it easier to improve the thermal conductivity of the resin composition.

[0021] (6) In any of the resin compositions described in (1) to (5) above, the tensile modulus of the resin composition at 25°C may be 5 GPa or less.

[0022] The resin composition described in (6) above is less prone to cracking.

[0023] (7) In any of the resin compositions described in (1) to (6) above, the tensile modulus of the resin composition at -40°C may be 5.6 GPa or less.

[0024] The resin composition described in (7) above can reduce the occurrence of cracks due to thermal shock in low-temperature environments.

[0025] (8) In any of the resin compositions described in (1) to (7) above, the thermal conductivity of the resin composition may be 1 W / m·K or more.

[0026] The resin composition described in (8) above has high thermal conductivity and therefore exhibits excellent heat dissipation properties.

[0027] (9) In any of the resin compositions described in (1) to (8) above, the coefficient of linear expansion of the resin composition is 15 × 10 －６ / ℃ or higher 30 x 10 －６ It is acceptable to have a temperature below / ℃.

[0028] The resin composition described in (9) above can be suitably used, for example, as an insulating material for electrical components such as reactors.

[0029] (10) In any of the resin compositions described in (1) to (9) above, the tensile strength of the resin composition may be 30 MPa or more.

[0030] The resin composition described in (10) above is less prone to cracking.

[0031] (11) A reactor according to an embodiment of the present disclosure includes a coil, a magnetic core, and an exterior resin layer. The coil has a wound portion formed by spirally winding a winding wire. The magnetic core includes an inner core portion disposed inside the wound portion and an outer core portion disposed outside the wound portion. The exterior resin layer covers at least a part of an outer circumferential surface of the wound portion. A material of the exterior resin layer is the resin composition according to any one of (1) to (10) above.

[0032] In the reactor of (11) above, since the exterior resin layer is formed of the resin composition described above, cracks are less likely to occur in the exterior resin layer.

[0033] (12) In the reactor of (11) above, a thickness of a portion of the exterior resin layer covering the wound portion may be 2.0 mm or less.

[0034] The reactor of (11) above easily dissipates heat generated in the coil through the exterior resin layer.

[0035] Hereinafter, specific examples of the resin composition and the reactor of the present disclosure will be described. The same reference numerals in the drawings denote the same or corresponding parts. In the drawings, for convenience of explanation, a part of the configuration may be exaggerated or simplified. The shapes, sizes, positional relationships, and the like shown in each drawing are expressed for the purpose of clarifying the explanation, and do not necessarily represent the actual shapes, sizes, positional relationships, and the like.

[0036] [Embodiment 1] <Resin Composition> In this disclosure, "resin composition" refers to the molded product. The resin composition 100 according to the embodiment will be described with reference to Figure 1. Figure 1 shows a cross-section of the molded resin composition 100. The resin composition 100 is used, for example, as an insulating material for electrical components such as reactors. The resin composition 100 includes a base resin 101, an inorganic filler 102, and a rubber filler 103. One of the features of the resin composition 100 is that the base resin 101 and the rubber filler 103 satisfy at least one of the following first and second conditions. The first condition is that the tensile modulus of the base resin 101 is 3 GPa or less. The second condition is that the glass transition temperature (Tg) of the rubber filler 103 is -40°C or less. The composition of the resin composition 100 will be described in detail below.

[0037] The specific combinations of base resin 101 and rubber filler 103 are as follows: (1) The first combination is a case that satisfies only the first condition. In this case, the base resin 101 is a resin with a low modulus of elasticity, and the rubber filler 103 is a rubber with a high Tg. (2) The second combination is a case that satisfies only the second condition. In this case, the base resin 101 is a resin with a high modulus of elasticity, and the rubber filler 103 is a rubber with a low Tg. (3) The third combination is a case that satisfies both the first and second conditions. In this case, the base resin 101 is a resin with a low modulus of elasticity, and the rubber filler 103 is a rubber with a low Tg. Here, a resin with a low modulus of elasticity is a resin with a tensile modulus of elasticity of 3 GPa or less. A resin with a high modulus of elasticity is a resin with a tensile modulus of elasticity greater than 3 GPa. Also, a rubber with a low Tg is a rubber with a Tg of -40°C or less. A rubber with a high Tg is a rubber with a Tg greater than -40°C. Hereafter, "tensile modulus" may simply be referred to as "modulus of elasticity."

[0038] <<Base Resin>> The base resin 101 has electrical insulating properties. The base resin 101 is, for example, made of a low elastic modulus resin that satisfies the first condition. When the rubber filler 103 is made of a low Tg rubber that satisfies the second condition, the material of the base resin 101 may be either a low elastic modulus resin or a high elastic modulus resin. The low elastic modulus resin is, for example, a polyamide resin (PA). The high elastic modulus resin is, for example, a polyphenylene sulfide resin (PPS).

[0039] The lower the elastic modulus of the base resin 101 is, the lower the elastic modulus of the resin composition 100 becomes. That is, the resin composition 100 becomes softer. By forming the base resin 101 from a low elastic modulus resin, not only cracks are less likely to occur when the resin composition 100 is molded, but also the occurrence of cracks due to thermal shock in a low-temperature environment can be reduced. The term "low temperature" as used herein refers to -40°C or lower. The elastic modulus of the low elastic modulus resin is, for example, 0.5 GPa or more and 3 GPa or less. The elastic modulus of the low elastic modulus resin may be 0.5 GPa or more and 2 GPa or less, 0.8 GPa or more and 1.8 GPa or less, and further 1 GPa or more and 1.6 GPa or less. The elastic modulus of the high elastic modulus resin is, for example, more than 3 GPa and 7 GPa or less. The elastic modulus of the high elastic modulus resin may be more than 3 GPa and 6 GPa or less, and further 3.5 GPa or more and 5 GPa or less. The elastic modulus of the base resin 101 referred to herein is the elastic modulus at 25°C.

[0040] The glass transition point of the base resin 101 is, for example, 90°C or higher. The higher the glass transition point of the base resin 101 is, the higher the heat resistance of the resin composition 100 becomes. The glass transition point of the base resin 101 may be 95°C or higher, and further 100°C or higher. The glass transition point of the base resin 101 is, for example, 180°C or lower. The glass transition point of the base resin 101 may be 90°C or more and 180°C or less, 95°C or more and 160°C or less, and further 100°C or more and 150°C or less.

[0041] The tensile strength of the base resin 101 is, for example, 30 MPa or more. The higher the tensile strength of the base resin 101, the higher the tensile strength of the resin composition 100. A resin composition 100 with high tensile strength is less prone to cracking. The tensile strength of the base resin 101 may be 40 MPa or more, and may even be 50 MPa or more. The tensile strength of the base resin 101 is, for example, 160 MPa or less. The tensile strength of the base resin 101 may be 30 MPa to 160 MPa, 40 MPa to 140 MPa, or 50 MPa to 120 MPa. The tensile strength of the base resin 101 referred to here is the tensile strength at 25°C.

[0042] The coefficient of linear expansion of the base resin 101 is, for example, 4 × 10⁻⁶ －５ / ℃ or higher 10 x 10 －５ It is below / °C. The coefficient of linear expansion of the base resin 101 is 5 × 10 －５ / ℃ or higher 8 x 10 －５ It may be below / °C. The coefficient of linear expansion of the base resin 101 referred to here is the coefficient of linear expansion in the temperature range of 0°C to 100°C.

[0043] The content of the base resin 101 is, for example, 24% to 76% by volume, relative to 100% by volume of the entire resin composition 100. A base resin content of 24% or more by volume makes the resin composition 100 easy to mold. A base resin content of 76% or less by volume allows the inorganic filler 102 and rubber filler 103 to be included in a certain or higher proportion.

[0044] ≪Inorganic Filler≫ The inorganic filler 102 is a granular material dispersed in the base resin 101. The inorganic filler 102 enhances the thermal conductivity of the resin composition 100. The inorganic filler 102 has electrical insulation properties and high thermal conductivity. The thermal conductivity of the inorganic filler 102 is higher than that of the base resin 101. The thermal conductivity of the inorganic filler 102 is, for example, 20 W / m·k or higher, and moreover, 30 W / m·k or higher. The material of the inorganic filler 102 is, for example, at least one ceramic selected from the group consisting of metal oxides, metal carbides, and metal nitrides. Examples of metal oxides include magnesium oxide (MgO) and silicon oxide (SiO2). ２ ) or aluminum oxide (Al２ O ３ ). The metal carbide is, for example, silicon carbide (SiC). The metal nitride is, for example, boron nitride (BN), silicon nitride (Si ３ N ４ ) or aluminum nitride (AlN).

[0045] When the entire resin composition 100 is 100% by volume, the content of the inorganic filler 102 is, for example, 20% by volume or more and 75% by volume or less. When the content of the inorganic filler 102 is 20% by volume or more, it is easy to improve the thermal conductivity of the resin composition 100. If the content of the inorganic filler 102 is too high, the resin composition 100 becomes hard and the elastic modulus of the resin composition 100 increases. If the content of the inorganic filler 102 is 75% by volume or less, the elastic modulus of the resin composition 100 is unlikely to become excessively high. In addition, when the content of the inorganic filler 102 is 75% by volume or less, it is easy to mix the inorganic filler 102 with the base resin 101. The content of the inorganic filler 102 may be 20% by volume or more and 70% by volume or less, and may further be 40% by volume or more and 60% by volume or less.

[0046] The shape of the inorganic filler 102 in this example is spherical. The average particle diameter of the inorganic filler 102 is, for example, 150 μm or less. When the average particle diameter of the inorganic filler 102 is 150 μm or less, the inorganic filler 102 is easily uniformly dispersed in the base resin 101. The average particle diameter of the inorganic filler 102 may be 100 μm or less. The average particle diameter of the inorganic filler 102 is, for example, 1 μm or more. The average particle diameter of the inorganic filler 102 is the average value of the particle diameters of the inorganic filler 102. The shape of the inorganic filler 102 may be fibrous or plate-shaped.

[0047] The average particle diameter of the inorganic filler 102 can be obtained, for example, by examining the particle size distribution with a commercially available measuring device using laser diffraction / scattering method, and calculating from the histogram of the obtained particle size distribution.

[0048] The inorganic filler 102 may be surface-treated with a silane coupling agent. Surface treatment of the inorganic filler 102 improves its wettability with the base resin 101, making it easier for the inorganic filler 102 to disperse uniformly in the base resin 101. The silane coupling agent is, for example, at least one selected from the group consisting of vinylsilane, aminosilane, isocyanatesilane, epoxysilane, methacrylicsilane, mercaptosilane, acrylicsilane, and ureidosilane.

[0049] ≪Rubber Filler≫ The rubber filler 103 is a granular material dispersed in the base resin 101. The rubber filler 103 lowers the elastic modulus of the resin composition 100. The rubber filler 103 is made of, for example, a low Tg rubber that satisfies the second condition. If the base resin 101 is made of a low elastic modulus resin that satisfies the first condition, the material of the rubber filler 103 may be a low Tg rubber or a high Tg rubber. A low Tg rubber is, for example, butadiene rubber (BR). A high Tg rubber is, for example, acrylic rubber (ACM).

[0050] The lower the Tg of the rubber filler 103, the lower the elastic modulus of the resin composition 100. In other words, the resin composition 100 becomes softer. Low-Tg rubber does not harden even at low temperatures of -40°C, and maintains a soft rubber state. When the rubber filler 103 is made of low-Tg rubber, the elastic modulus of the resin composition 100 is low even in low-temperature environments. By making the rubber filler 103 of low-Tg rubber, not only is it difficult for cracks to occur when the resin composition 100 is molded, but the occurrence of cracks due to thermal shock in low-temperature environments can also be reduced. The Tg of low-Tg rubber may be -40°C or lower, -60°C or lower, or even -80°C or lower. For example, the Tg of low-Tg rubber may be -140°C or higher. The Tg of high-Tg rubber may be above -40°C, or even above -30°C. For example, the Tg of high-Tg rubber may be below 0°C.

[0051] The content of the rubber filler 103 is, for example, 1% to 6% by volume, with the total resin composition 100 being 100% by volume. A rubber filler content of 1% or more by volume makes it easier to lower the elastic modulus of the resin composition 100. A rubber filler content of 6% or less by volume makes it easier to mix with the base resin 101. The rubber filler content may also be 1% to 5% by volume.

[0052] In this example, the shape of the rubber filler 103 is spherical. The average particle size of the rubber filler 103 is, for example, 20 μm or less. Having an average particle size of 20 μm or less makes it easier for the rubber filler 103 to disperse uniformly in the base resin 101. The average particle size of the rubber filler 103 may also be 10 μm or less. The average particle size of the rubber filler 103 is, for example, 0.1 μm or more. The average particle size of the rubber filler 103 is the average value of the particle sizes of the rubber filler 103. The shape of the rubber filler 103 may also be fibrous or plate-like.

[0053] The average particle size of the rubber filler 103 can be determined, in the same way as the inorganic filler 102, by examining the particle size distribution using a commercially available measuring device that employs laser diffraction and scattering methods, and then obtaining the resulting histogram of the particle size distribution.

[0054] <<Other Components>> In addition to the base resin 101, inorganic filler 102, and rubber filler 103, the resin composition 100 may contain other components as needed. These other components are additives such as flame retardants, colorants, curing agents, and coupling agents. The content of these other components is not particularly limited as long as it does not significantly impair the effects of the present disclosure. The content of these other components is, for example, less than 1% by mass when the base resin 101 is considered to be 100% by mass.

[0055] ≪Characteristics of the Resin Composition≫ The resin composition 100 has a low modulus of elasticity because the base resin 101 is made of a resin with a low modulus of elasticity, or the rubber filler 103 is made of rubber with a low Tg. A resin composition 100 with a low modulus of elasticity is less prone to cracking. In addition, the resin composition 100 has high thermal conductivity because it contains an inorganic filler 102. A resin composition 100 with high thermal conductivity has excellent heat dissipation properties.

[0056] [Tensile Modulus] The elastic modulus of the resin composition 100 at 25°C is, for example, 5 GPa or less. Having an elastic modulus of 5 GPa or less at 25°C makes it difficult for cracks to occur in the resin composition 100. The elastic modulus at 25°C may also be 4.8 GPa or less. Furthermore, the elastic modulus of the resin composition 100 at -40°C is, for example, 5.6 GPa or less. Having an elastic modulus of 5.6 GPa or less at -40°C reduces the occurrence of cracks in low-temperature environments. The elastic modulus at -40°C may be 5.5 GPa or less, and even 5 GPa or less.

[0057] [Tensile Strength] The tensile strength of the resin composition 100 is, for example, 30 MPa or more. A tensile strength of 30 MPa or more makes it difficult for cracks to occur in the resin composition 100. The tensile strength of the resin composition 100 may be 40 MPa or more, and even 50 MPa or more. The tensile strength of the resin composition 100 is, for example, 160 MPa or less. The tensile strength of the resin composition 100 may be 30 MPa or more and 160 MPa or less, 40 MPa or more and 140 MPa or less, or 50 MPa or more and 120 MPa or less. The tensile strength of the resin composition 100 referred to here is the tensile strength at 25°C.

[0058] [Thermal Conductivity] The thermal conductivity of the resin composition 100 is, for example, 1 W / m·K or higher. A thermal conductivity of 1 W / m·K or higher improves the heat dissipation of the resin composition 100. The thermal conductivity may be 2 W / m·K or higher, 3 W / m·K or higher, or even 5 W / m·K or higher.

[0059] [Coefficient of linear expansion] The coefficient of linear expansion of the resin composition 100 is, for example, 15 × 10⁻⁶. －６ / ℃ or higher 30 x 10 －６ It is below / °C. When the outer resin layer 6 of the reactor 1 (see Figure 2), which will be described later, is formed from the resin composition 100, residual stress is generated in the outer resin layer 6 due to the difference in the coefficient of linear expansion between the resin composition 100 and the coil 2. Since the coefficient of linear expansion is within the above range, the residual stress due to the difference in the coefficient of linear expansion is small, making it easier to reduce the occurrence of cracks in the outer resin layer 6. The coefficient of linear expansion is 20 × 10 －６ / ℃ or higher 30 x 10 －６ It may be less than / °C. The coefficient of linear expansion of the resin composition 100 referred to here is the coefficient of linear expansion in the temperature range of 0°C to 100°C.

[0060] [Embodiment 2] <Reactor> A reactor 1 according to an embodiment will be described with reference to Figures 2 to 4. As shown in Figure 2, the reactor 1 comprises a coil 2, a magnetic core 3, and an outer resin layer 6. In Figure 2, the outer resin layer 6 is shown by a dashed line so that the shapes of the coil 2 and the magnetic core 3 can be seen. The reactor 1 may further comprise two spacers 4 and 5. The configuration of the reactor 1 will be described below.

[0061] <Coil> The coil 2 has a winding section 21. The coil 2 in this example has one winding section 21. The winding section 21 is formed by winding the winding wire 7 in a spiral shape. The winding wire 7 has a conductor wire 70 and an insulating coating 76 that covers the outer circumference of the conductor wire 70. The conductor wire 70 is made of, for example, copper, a copper alloy, aluminum, or an aluminum alloy. The insulating coating 76 is made of, for example, enamel. The winding wire 7 in this example is a flat rectangular wire. The shape of the cross-section perpendicular to the length of the conductor wire 70 is rectangular. The winding section 21 in this example is formed by winding the winding wire 7, which is a flat rectangular wire, edgewise. The winding section 21 may also be formed by winding the flat rectangular wire flatwise. The winding wire 7 may also be a round wire.

[0062] In this example, the winding portion 21 is rectangular in shape. The winding portion 21 has a flattened shape when viewed from a direction along its axis. As shown in Figure 4, the cross-sectional shape perpendicular to the axis of the winding portion 21 is rectangular. The cross-sectional shape perpendicular to the axis of the winding portion 21 may also be oval. An oval-shaped winding portion, when viewed from a direction along its axis, consists of two parallel straight sections and two curved sections. The two curved sections connect the ends of the two straight sections, respectively. Each curved section is semicircular in shape.

[0063] Here, the direction in the reactor 1 is defined with respect to coil 2. First, the direction along the axis of the winding portion 21 is direction X. Direction X1 is the direction along the axis of the winding portion 21 from the first end to the second end of the winding portion 21. Direction Y1 is the direction from the first side surface to the second side surface of the winding portion 21. Direction Y1 is perpendicular to direction X1. The first side surface and the second side surface are the surfaces that form the short side when the flattened winding portion 21 is viewed in direction X1. Direction Z1 is the direction perpendicular to both direction X1 and direction Y1. Directions X2, Y2, and Z2 are the opposite directions of direction X1, Y1, and Z1, respectively.

[0064] The winding portion 21 in this example has a thin, flattened shape in direction Z1. The flattened winding portion 21 has a first surface 21A facing direction Z1 and a second surface 21B facing direction Z2. The second surface 21B is located on the opposite side of the first surface 21A. The first surface 21A and the second surface 21B are parallel to each other. The ratio H / W of the width W (see Figure 2) to the height H (see Figure 3) of the winding portion 21 is, for example, 1 / 20 or more and less than 1. The width W is the length of the winding portion 21 along direction Y1. The height H is the length of the winding portion 21 along direction Z1. As shown in Figure 3, in this example, the first surface 21A of the winding portion 21 and the surface of the outer core portion 32 facing direction Z1 are contained in one virtual plane, and the second surface 21B of the winding portion 21 and the surface of the outer core portion 32 facing direction Z2 are contained in one virtual plane. Therefore, the height H of the winding portion 21 is equal to the height of the outer core portion 32. The ratio H / W may be 1 / 15 or more and less than 1, or 1 / 10 or more and less than 1. A coil 2 having such a flattened winding portion 21 allows for a thinner reactor 1.

[0065] The ends 22 and 23 of the winding 7 are drawn out from the winding section 21. In this example, as shown in Figure 2, both ends 22 and 23 are drawn out from the winding section 21 in direction Y2. The insulating coating 76 is stripped from ends 22 and 23, exposing the conductor wires 70. A terminal member (not shown) is connected to the exposed conductor wires 70. The terminal member is connected to a power source, for example. Ends 22 and 23 are within the height H range of the winding section 21. Therefore, ends 22 and 23 do not increase the dimensions of the winding section 21 in direction Z1.

[0066] ≪Magnetic Core≫ A closed magnetic path is formed in the magnetic core 3 when current flows through the coil 2. The magnetic core 3 has an inner core portion 31 and an outer core portion 32. In Figure 3, the boundary between the inner core portion 31 and the outer core portion 32 is shown by a dashed line. The inner core portion 31 is the part located inside the winding portion 21. The inner core portion 31 extends along the axis of the winding portion 21. The number of inner core portions 31 is the same as the number of winding portions 21. In this example, there is one inner core portion 31. In this example, both ends of the portion of the magnetic core 3 that lies along the axis of the winding portion 21 protrude from the end face of the winding portion 21. These protruding portions are also part of the inner core portion 31.

[0067] The outer core portion 32 is the part located on the outside of the winding portion 21. The shape of the outer core portion 32 is not particularly limited as long as it connects the ends of the inner core portion 31. As shown in Figure 2, the outer core portion 32 in this example has a first end core portion 32a, a second end core portion 32b, and a side core portion 32c. The first end core portion 32a is positioned to face the end face in direction X1 of the winding portion 21. The second end core portion 32b is positioned to face the end face in direction X2 of the winding portion 21. The side core portion 32c is positioned to face the side surface in direction Y1 of the winding portion 21. The outer core portion 32 has an angular C-shape when viewed in direction Z2. Unlike this example, there may be two side core portions. In that case, the outer core portion 32 has a side core portion facing the side surface in direction Y2 of the winding portion 21 in addition to the side core portion 32c. Such an outer core portion 32 is rectangular and annular when viewed in direction Z2. In addition, when the number of winding portions 21 and the number of inner core portions 31 are two, the outer core portion 32 is formed by, for example, a first end core portion connecting the ends of the two inner core portions in direction X1 and a second end core portion connecting the ends of the two inner core portions in direction X2.

[0068] The magnetic core 3 is made of, for example, a compacted powder or a molded composite material. The magnetic core 3 may be formed by combining a core piece made of a compacted powder and a core piece made of a molded composite material, or it may be formed by covering the outer circumference of a core piece made of a compacted powder with a composite material. In this example, the magnetic core 3 is made of a molded composite material.

[0069] The compacted body is formed by pressure molding a raw material powder containing soft magnetic powder. The soft magnetic powder is, for example, pure iron or an iron alloy. The iron alloy is, for example, an Fe (iron)-Si (silicon) alloy or an Fe-Ni (nickel) alloy. The raw material powder may contain a lubricant. The soft magnetic powder content in the compacted body is, for example, more than 80% by volume, and more specifically 85% or more by volume, when the entire compacted body is considered as 100% by volume.

[0070] A molded composite material is produced by filling a mold with a mixture of soft magnetic powder and unsolidified resin, and then solidifying the resin. In the molded composite material, the soft magnetic powder is dispersed in the resin. The resin is, for example, PPS. The content of soft magnetic powder in the composite material is, for example, 30% to 80% by volume when the total volume of the composite material is considered to be 100% by volume. The content of soft magnetic powder in the composite material may be 50% or more by volume, 60% or more by volume, or even 70% or more by volume.

[0071] <Outer Resin Layer> The outer resin layer 6 covers at least a portion of the outer surface of the winding portion 21. The outer resin layer 6 may be placed on only one of the first surface 21A and the second surface 21B of the winding portion 21, or on both surfaces. As shown in Figures 3 and 4, in this example, the outer resin layer 6 covers not only the first surface 21A and the second surface 21B, but the entire assembly of the coil 2 and the magnetic core 3. The coefficient of linear expansion of the coil 2 is, for example, 18 × 10⁻⁶. －６ It is approximately / °C. The coefficient of linear expansion of the molded composite material forming the magnetic core 3 is, for example, 17 × 10⁻⁶. －６ It is approximately / ℃.

[0072] The material of the exterior resin layer 6 in this example is the resin composition 100 according to the embodiment described above. Because the exterior resin layer 6 is made of the resin composition 100, cracks are less likely to occur in the exterior resin layer 6. In addition, because the exterior resin layer 6 has a high thermal conductivity, it is easy to dissipate the heat generated in the coil 2.

[0073] The thickness of the outer resin layer 6 covering the winding portion 21 is, for example, 2.0 mm or less. A thickness of 2.0 mm or less in the outer resin layer 6 makes it easier to dissipate heat generated in the coil 2. The thickness of the outer resin layer 6 may also be 1.5 mm or less. The thickness of the outer resin layer 6 is, for example, 0.5 mm or more. A thickness of 0.5 mm or more in the outer resin layer 6 makes it easier to electrically insulate the coil 2. The thickness of the outer resin layer 6 may also be 0.6 mm or more and 1.5 mm or less.

[0074] The outer resin layer 6 can be formed by injection molding. The outer resin layer 6 is formed, for example, as follows: The assembly of the coil 2 and the magnetic core 3 is placed in a mold, a mixture of molten base resin, inorganic filler and rubber filler is filled into the mold, and the resin composition is molded by cooling and solidifying. The outer resin layer 6 may also be formed by transfer molding.

[0075] Spacers are components that electrically insulate the coil 2 from the magnetic core 3. Spacer 4 is placed between the end face of the winding portion 21 and the first end core portion 32a of the outer core portion 32. Spacer 5 is placed between the end face of the winding portion 21 and the second end core portion 32b of the outer core portion 32. Spacers 4 and 5 electrically insulate the winding portion 21 from the outer core portion 32.

[0076] [Embodiment 3] <Converter / Power Conversion Device> The reactor 1 according to the above embodiment can be used for applications that satisfy the following energizing conditions. For example, the energizing conditions are that the maximum DC current is approximately 100A to 1000A, the average voltage is approximately 100V to 1000V, and the operating frequency is approximately 5kHz to 100kHz. The reactor 1 is typically used as a component of a converter installed in a vehicle such as an electric vehicle or a hybrid vehicle, or as a component of a power conversion device equipped with this converter.

[0077] As shown in Figure 5, a vehicle 1200 such as a hybrid vehicle or electric vehicle includes a main battery 1210, a power converter 1100 connected to the main battery 1210, and a drive motor 1220 that drives the wheels using power supplied from the main battery 1210. The motor 1220 is typically a three-phase AC motor, which drives the wheels 1250 during driving and functions as a generator during regeneration. In the case of a hybrid vehicle, the vehicle 1200 is equipped with an engine 1300 in addition to the motor 1220. In Figure 5, the charging point of the vehicle 1200 is an inlet, but it may also be equipped with a plug.

[0078] The power conversion device 1100 includes a converter 1110 connected to the main battery 1210 and an inverter 1120 connected to the converter 1110 that performs mutual conversion between DC and AC. In this example, the converter 1110 boosts the input voltage of the main battery 1210, which is approximately 200V to 300V, to approximately 400V to 700V when the vehicle 1200 is running, and supplies power to the inverter 1120. During regeneration, the converter 1110 steps down the input voltage output from the motor 1220 via the inverter 1120 to a DC voltage suitable for the main battery 1210, thereby charging the main battery 1210. The input voltage is a DC voltage. When the vehicle 1200 is running, the inverter 1120 converts the DC voltage boosted by the converter 1110 into a predetermined AC voltage and supplies power to the motor 1220. During regeneration, it converts the AC output from the motor 1220 into DC voltage and outputs it to the converter 1110.

[0079] As shown in Figure 6, the converter 1110 comprises a plurality of switching elements 1111, a drive circuit 1112 that controls the operation of the switching elements 1111, and a reactor 1115, and converts the input voltage by repeatedly switching ON / OFF. In this case, the input voltage conversion is step-up or step-down. Power devices such as field-effect transistors and insulated-gate bipolar transistors are used as switching elements 1111. The reactor 1115 utilizes the coil property that tries to oppose changes in the current that is about to flow through the circuit, and has the function of smoothing the change when the current tries to increase or decrease due to the switching operation. The reactor 1115 is provided as reactor 1 according to the embodiment.

[0080] In addition to the converter 1110, the vehicle 1200 is equipped with a power supply device converter 1150 connected to the main battery 1210, and an auxiliary power converter 1160 connected to the main battery 1210 and a sub-battery 1230 which serves as a power source for auxiliary equipment 1240, and which converts the high voltage of the main battery 1210 to a low voltage. The converter 1110 typically performs DC-DC conversion, while the power supply device converter 1150 and the auxiliary power converter 1160 perform AC-DC conversion. Some power supply device converters 1150 also perform DC-DC conversion. The reactors of the power supply device converter 1150 and the auxiliary power converter 1160 have the same configuration as reactor 1, etc. according to the embodiment, and reactors with appropriately changed size and shape can be used. Furthermore, reactor 1, etc. according to the embodiment can also be used for converters that convert input power, such as converters that only perform boosting or converters that only perform step-down.

[0081] [Test Example] A sample of a resin composition was prepared. The materials of the resin composition were a base resin, an inorganic filler, and a rubber filler, all of which were commercially available. PA or PPS was used as the base resin. The PA used was PA9T. The properties of PA9T and PPS are shown in Table 1.

[0082]

[0083] MgO powder was used as the inorganic filler. The particle size of the MgO powder was 300 μm or less. The average particle size of the MgO powder was 70 μm. In addition, the MgO powder was surface-treated with a vinyl-based silane coupling agent.

[0084] The rubber filler used was either BR powder or ACM powder. The Tg of BR is -110°C to -90°C. The Tg of ACM is -20°C to -10°C. The particle size of both the BR powder and the ACM powder is 20 μm or less. The average particle size of the BR powder is 0.18 μm. The average particle size of the ACM powder is 5 μm.

[0085] A resin composition was prepared by mixing a base resin, an inorganic filler, and a rubber filler, and then molding the resulting material to produce a molded resin body. The resin composition was molded by injection molding. In this test example, the base resin material, the base resin content, the rubber filler material, and the rubber filler content were all varied to produce the samples shown in Table 2. In Table 2, the unit of the content percentage is "volume %".

[0086] The elastic modulus, tensile strength, thermal conductivity, and coefficient of linear expansion were measured for molded articles of the manufactured resin composition.

[0087] The modulus of elasticity and tensile strength were measured in accordance with JIS K 7161-1:2014 and JIS K 7161-2:2014. A Shimadzu AGS-1kNX benchtop precision universal testing machine was used for the measurements of modulus of elasticity and tensile strength. The modulus of elasticity was measured at 25°C and -40°C. The modulus of elasticity at 25°C and -40°C are shown in Table 2. The tensile strength was measured at 25°C. The tensile strength is shown in Table 2.

[0088] Thermal conductivity was measured using the laser flash method. A TC-9000 laser flash thermal constant measuring device manufactured by ULVAC, Inc. was used for the measurement. The measurement was performed at 25°C. The thermal conductivity values ​​are shown in Table 2.

[0089] The coefficient of linear thermal expansion was measured in accordance with JIS K 7197:2012. A thermomechanical analyzer TMA7100C manufactured by Hitachi High-Tech Science Corporation was used for the measurement of the coefficient of linear thermal expansion. The coefficient of linear thermal expansion was measured in the temperature range of 0°C to 100°C. The coefficients of linear thermal expansion are shown in Table 2.

[0090]

[0091] As shown in Table 2, samples No. 1 to No. 6 have lower elastic moduli compared to sample No. 0. The elastic moduli of samples No. 1 to No. 6 at 25°C are 5 GPa or less. Furthermore, the elastic moduli of samples No. 1 to No. 6 at -40°C are 5.6 GPa or less. The reasons why the elastic moduli of samples No. 1 to No. 6 are lower than those of sample No. 0 are thought to be as follows: Samples No. 1 to No. 3 use BR as the rubber filler material. It is thought that the elastic moduli of the resin composition are lower because the rubber filler is made of low Tg rubber. Samples No. 4 to No. 6 use PA9T as the base resin material. It is thought that the elastic moduli of the resin composition are lower because the base resin is made of a resin with a low elastic moduli.

[0092] Furthermore, the results shown in Table 2 indicate that, given the same base resin material, a higher proportion of rubber filler results in a lower elastic modulus of the resin composition.

[0093] The tensile strength of samples No. 1 to No. 6 is 30 MPa or higher. Samples No. 1 to No. 6 have relatively high tensile strength while having a low modulus of elasticity, making them less prone to cracking.

[0094] The thermal conductivity of samples No. 1 to No. 6 is 2 W / m·K or higher. Since samples No. 1 to No. 6 have relatively high thermal conductivity, they also have excellent heat dissipation properties.

[0095] The coefficients of linear thermal expansion for samples No. 1 through No. 6 are 15 × 10⁻⁶. －６ / ℃ or higher 30 x 10 －６ The temperature is below / °C. Samples No. 1 to No. 6 are suitable as materials for the outer resin layer of the reactor because their coefficients of linear expansion satisfy the above range.

[0096] It should be understood that the present invention is not limited to these examples, but is as indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included. At least one configuration or feature described in each embodiment and example can be combined with other embodiments and examples, or modified in various ways.

[0097] 1 Reactor 2 Coil 3 Magnetic core 4 Spacer 5 Spacer 6 Outer resin layer 7 Winding 21 Winding section 21A First surface 21B Second surface 22, 23 End sections 31 Inner core section 32 Outer core section 32a First end core section 32b Second end core section 32c Side core section 70 Conductor wire 76 Insulation coating 100 Resin composition 101 Base resin 102 Inorganic filler 103 Rubber filler 1100 Power conversion device 1110 Converter 1111 Switching element 1112 Drive circuit 1115 Reactor 1120 Inverter 1150 Converter for power supply device 1160 Converter for auxiliary power supply 1200 Vehicle 1210 Main battery 1220 Motor 1230 Sub-battery 1240 Auxiliary equipment 1250 Wheels 1300 Engine H Height W Width

Claims

1. A resin composition comprising a base resin, an inorganic filler, and a rubber filler, wherein the base resin and the rubber filler satisfy at least one of a first condition and a second condition, the first condition being that the tensile modulus of the base resin is 3 GPa or less, and the second condition being that the glass transition temperature of the rubber filler is -40°C or less.

2. The resin composition according to claim 1, wherein the rubber filler is made of rubber that satisfies the second condition, and the material of the rubber filler is butadiene rubber.

3. The resin composition according to claim 1 or claim 2, wherein the base resin is made of a resin that satisfies the first condition, and the material of the base resin is a polyamide resin.

4. The resin composition according to claim 1 or claim 2, wherein the content of the rubber filler is 1% by volume or more and 6% by volume or less.

5. The resin composition according to claim 1 or claim 2, wherein the inorganic filler content is 20% by volume or more and 75% by volume or less.

6. The resin composition according to claim 1 or claim 2, wherein the tensile modulus of the resin composition at 25°C is 5 GPa or less.

7. The resin composition according to claim 1 or claim 2, wherein the tensile modulus of the resin composition at -40°C is 5.6 GPa or less.

8. The resin composition according to claim 1 or claim 2, wherein the thermal conductivity of the resin composition is 1 W / m·K or more.

9. The coefficient of linear expansion of the resin composition is 15 × 10 －６ / ℃ or higher 30 x 10 －６ The resin composition according to claim 1 or claim 2, wherein the temperature is below / ℃.

10. The resin composition according to claim 1 or claim 2, wherein the resin composition has a tensile strength of 30 MPa or more.

11. A reactor comprising a coil, a magnetic core, and an outer resin layer, wherein the coil has a winding portion in which the windings are wound in a spiral shape, the magnetic core has an inner core portion disposed inside the winding portion and an outer core portion disposed outside the winding portion, the outer resin layer covers at least a part of the outer circumferential surface of the winding portion, and the material of the outer resin layer is the resin composition according to claim 1 or claim 2.

12. The reactor according to claim 11, wherein the thickness of the portion of the outer resin layer that covers the winding portion is 2.0 mm or less.

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