Magnetic resin composition, magnetic paste, magnetic sheet, and molded body

Abstract

The present disclosure addresses the problem of providing a magnetic resin composition which is capable of simultaneously achieving improvement of magnetic characteristics, improvement of fluidity, and suppression of deformation such as warpage that may occur in a cured product thereof. This magnetic resin composition contains: a thermosetting resin (A); an elastomer (B) which includes a thermoplastic resin (B-1) that is in a liquid state at 25°C; and a magnetic filler (C). The thermoplastic resin (B-1) includes at least one resin that is selected from the group consisting of polyester polyol resins and (meth)acrylic resins. The content of the elastomer (B) is 0.05 mass% to 1.50 mass% inclusive with respect to the total amount of the solid content of the magnetic resin composition.

Description

Magnetic resin composition, magnetic paste, magnetic sheet, and molded article

[0001] This disclosure generally relates to magnetic resin compositions, magnetic pastes, magnetic sheets, and molded articles, and more particularly to magnetic resin compositions containing magnetic fillers, magnetic pastes, magnetic sheets, and molded articles made from magnetic resin compositions.

[0002] Patent Document 1 discloses a resin composition containing (A) a thermosetting resin, (B) a curing agent, (C) a thermoplastic resin, (D) a magnetic filler, and (E) an inorganic filler other than a magnetic filler, wherein when the mass of component (D) is d1 and the mass of component (E) is e1, e1 / d1 is 0.02 or more and 0.19 or less. The adhesive film obtained using the above resin composition has excellent lamination properties, and the cured product of the resin composition has excellent flame retardancy, suppresses warping, and in particular can improve relative permeability in the frequency range of 10 to 200 MHz.

[0003] When attempting to further improve the relative permeability of the cured resin composition as described above, one method is to increase the content of (D) magnetic filler. However, increasing the amount of (D) magnetic filler contained in the resin composition may reduce the fluidity of the resin composition, or make it more difficult to suppress deformation such as warping that occurs in the cured product. Therefore, there is a problem in that it is difficult to simultaneously achieve improved magnetic properties, improved fluidity, and suppression of deformation such as warping that occurs in the cured product with the above resin composition.

[0004] International Publication No. 2018 / 194100

[0005] The object of this disclosure is to provide a magnetic resin composition, magnetic paste, magnetic sheet, and molded article that can simultaneously achieve improved magnetic properties, improved fluidity, and suppression of deformation such as warping that occurs in the cured product.

[0006] The magnetic resin composition of this disclosure comprises a thermosetting resin (A), an elastomer (B) containing a thermoplastic resin (B-1) that is liquid at 25°C, and a magnetic filler (C), wherein the thermoplastic resin (B-1) comprises at least one selected from the group consisting of polyester polyol resins and (meth)acrylic resins. The content of the elastomer (B) is 0.05% by mass or more and 1.50% by mass or less, based on the total amount of solids in the magnetic resin composition.

[0007] The magnetic paste of this disclosure comprises the magnetic resin composition.

[0008] The magnetic sheet of this disclosure includes the magnetic resin composition or a semi-cured product of the magnetic resin composition.

[0009] The molded article of this disclosure includes a cured product of the magnetic resin composition.

[0010] Embodiments of this disclosure will now be described. Note that the embodiments described below are only a selection of the various embodiments of this disclosure. Furthermore, the embodiments described below can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. Also, the mechanisms of operation described below are speculative, and this disclosure is not bound by the following explanation of the mechanisms of operation. In the following description, "(meta)acrylic" is a general term encompassing "acrylic" and "methacrylic," and refers to either "acrylic" or "methacrylic," or "acrylic" and "methacrylic."

[0011] 1. Overview The magnetic resin composition according to the embodiment (hereinafter also referred to as composition (M)) is a magnetic resin composition containing a thermosetting resin (A), an elastomer (B) containing a thermoplastic resin (B-1) that is liquid at 25°C, and a magnetic filler (C), wherein the thermoplastic resin (B-1) includes at least one selected from the group consisting of polyester polyol resin and (meth)acrylic resin. The content of elastomer (B) is 0.05% by mass or more and 1.50% by mass or less, based on the total amount of solids in composition (M).

[0012] According to the above configuration, composition (M) can simultaneously achieve improved magnetic properties, improved fluidity, and suppression of deformation such as warping that occurs in the cured product. In other words, because composition (M) contains a magnetic filler (C), it can improve magnetic properties. On the other hand, when composition (M) contains a magnetic filler (C), fluidity tends to decrease, or deformation such as warping that occurs in the cured product tends to occur. However, in contrast to this, composition (M) contains an elastomer (B) containing a thermoplastic resin (B-1) that is liquid at 25°C and contains a specific compound, in a specific proportion. Therefore, even if composition (M) contains a magnetic filler (C), it can suppress a decrease in fluidity and suppress deformation such as warping that occurs in the cured product. In this disclosure, deformation such as warping that occurs in the cured product refers to deformation such as warping that occurs due to shrinkage that occurs when a cured product manufactured by heating and curing composition (M) cools down.

[0013] The solid content of composition (M) refers to the components remaining after removing volatile components such as solvents from composition (M), and includes the resin component (R) and the magnetic filler (C). Therefore, the solvent is not included in the resin component (R).

[0014] 2. Magnetic Resin Composition The magnetic resin composition according to the embodiment will be described.

[0015] 2.1 Composition As described above, composition (M) contains a resin component (R) and a magnetic filler (C). The resin component (R) contains a thermosetting resin (A) and an elastomer (B).

[0016] (Thermosetting resin) As described above, composition (M) contains thermosetting resin (A). When composition (M) is heated, the thermosetting resin (A) hardens, and a cured product of composition (M) can be produced.

[0017] The thermosetting resin (A) may be liquid or solid at 25°C, but it is preferable that it be liquid. In this case, the fluidity of composition (M) can be improved. The thermosetting resin (A) may also consist of a liquid component and a solid component.

[0018] The thermosetting resin (A) includes at least one selected from the group consisting of, for example, epoxy resin (A-1), silicone resin, polyphenylene ether resin, phenol resin, maleimide resin, and benzoxazine resin. Among these, epoxy resin (A-1) is preferred. In other words, it is preferable that the thermosetting resin (A) includes epoxy resin (A-1). In this case, the curing of the thermosetting resin (A) proceeds more easily.

[0019] Epoxy resins (A-1) include, for example, alkylphenol novolac type epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins; naphthol novolac type epoxy resins; phenol aralkyl type epoxy resins having a phenylene skeleton, biphenylene skeleton, etc.; biphenyl aralkyl type epoxy resins; naphthol aralkyl type epoxy resins having a phenylene skeleton, biphenylene skeleton, etc.; polyfunctional epoxy resins such as triphenolmethane type epoxy resins and alkyl-modified triphenolmethane type epoxy resins; triphenylmethane type epoxy resins; tetrakisphenolethane type epoxy resins; dicyclop The epoxy resin (A-1) is preferably in liquid form, but is not limited to liquid form and may be in solid form.

[0020] The thermosetting resin (A) may contain a curing agent. It is sufficient that the curing agent can cure the thermosetting components, such as the thermosetting resin, in composition (M). The curing agent includes, for example, at least one selected from the group consisting of phenolic curing agents, acid anhydride curing agents, amine curing agents, imidazole curing agents, and phosphorus curing agents. Among these, amine curing agents are preferably used. Examples of amine curing agents include dicyandiamide and aromatic amines.

[0021] (Elastomer) As described above, composition (M) contains elastomer (B), and the elastomer (B) content is 0.05% by mass or more relative to the total amount of solids in composition (M). This suppresses deformation such as warping that occurs in the cured product. The reason why deformation such as warping that occurs in the cured product can be suppressed by including elastomer (B) in a specific proportion has not been precisely clarified, but it is presumed to be due to the following reasons.

[0022] When a composition containing magnetic particles and a thermosetting component is heated, the thermosetting component hardens, forming a cured product of the composition. When the heated and formed cured product cools, shrinkage occurs in the hardened thermosetting component, and this shrinkage causes deformation such as warping to occur throughout the cured product of the composition.

[0023] In contrast, in this embodiment, composition (M) contains elastomer (B) in a specific proportion. In this case, the elastic modulus of the cured product can be reduced, making it easier to suppress deformation such as warping that occurs throughout the cured product. Furthermore, the cured product of such composition (M) may have a continuous phase formed from cured thermosetting resin (A) and a dispersed phase formed from elastomer (B). In other words, a sea-island structure may be formed in the cured product, with the cured thermosetting resin (A) as the sea and the elastomer (B) as the islands. When this cured product cools, shrinkage may occur in the cured thermosetting resin (A) and elastomer (B), but elastomer (B) tends to shrink more than the cured thermosetting resin (A). Therefore, a force may be generated in the elastomer (B) that forms the dispersed phase, pulling the cured thermosetting resin (A) that forms the continuous layer inward. This can mitigate the shrinkage that occurs in the cured thermosetting resin (A) and reduce the coefficient of linear expansion of the cured product. As a result, deformations such as warping that occur throughout the hardened material can be more easily suppressed.

[0024] Through this mechanism, by incorporating elastomer (B) into composition (M) in a specific proportion, deformation such as warping that occurs in the cured product can be suppressed. The elastomer (B) content is 1.50% by mass or less relative to the total amount of solids in composition (M). As a result, composition (M) can suppress the bleed-out of elastomer (B) during the curing reaction.

[0025] Furthermore, the elastomer (B) content is preferably 0.10% by mass or more, and more preferably 0.20% by mass or more, based on the total amount of solids in composition (M). The elastomer (B) content is preferably 1.20% by mass or less, more preferably 1.00% by mass or less, and even more preferably 0.60% by mass or less, based on the total amount of solids in composition (M).

[0026] The elastomer (B) may be liquid or solid, but it is preferably liquid. In this case, the fluidity of composition (M) can be improved. The elastomer (B) can be a combination of liquid and solid components.

[0027] The viscosity of elastomer (B) is preferably 1000 Pa·s or less at 25°C. In this case, the fluidity of composition (M) can be further improved. This viscosity is more preferably 500 Pa·s or less, even more preferably 300 Pa·s or less, and particularly preferably 100 Pa·s or less. Furthermore, from the viewpoint of suppressing the bleed-out of elastomer (B) during the curing reaction, this viscosity is preferably 0.1 Pa·s or more.

[0028] The elastomer (B) preferably contains at least one selected from the group consisting of polyester polyol resin and (meth)acrylic resin. The (meth)acrylic resin is a copolymer of (meth)acrylate. The (meth)acrylate includes, for example, at least one selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. Among these, butyl acrylate is preferred. The glass transition temperature of the thermoplastic resin can be lowered. This makes it easier to suppress deformation such as warping that occurs in the cured product.

[0029] Furthermore, polyester polyol resin is a condensation polymer of glycol and dicarboxylic acid. The glycol includes, for example, at least one selected from the group consisting of ethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, polypropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol. Among these, polypropylene glycol is preferably used. The dicarboxylic acid includes, for example, at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phthalic acid, terephthalic acid residue, and isophthalic acid residue. Among these, isophthalic acid and sebacic acid are preferably used. Therefore, the polyester polyol resin is preferably a condensation polymer of polypropylene glycol, isophthalic acid, and sebacic acid.

[0030] In this embodiment, the elastomer (B) comprises a thermoplastic resin (B-1) that is liquid at 25°C, and the thermoplastic resin (B-1) comprises at least one selected from the group consisting of polyester polyol resin and (meth)acrylic resin. In this case, deformation such as warping that occurs in the cured product can be suppressed, and the fluidity of the composition (M) can be improved.

[0031] Examples of molecular forms for the thermoplastic resin (B-1) include oligomers, prepolymers, or polymers, but oligomers are preferred. In this case, it is easier to improve the fluidity of composition (M) and suppress deformation such as warping that occurs in the cured product, and composition (M) can suppress the bleed-out of elastomer (B) during the curing reaction.

[0032] Incidentally, the weight-average molecular weight of the thermoplastic resin (B-1) is preferably 1,000 or more and 9,000 or less. When the weight-average molecular weight is 1,000 or more, it is easy to suppress deformation such as warping that occurs in the cured product, and the composition (M) can suppress the bleed-out of the elastomer (B) during the curing reaction. When the weight-average molecular weight is 9,000 or less, it is easy to improve the fluidity of the composition (M). This weight-average molecular weight is more preferably 1,500 or more. This weight-average molecular weight is more preferably 9,000 or less, and even more preferably 5,000 or less. The weight-average molecular weight refers to the weight-average molecular weight in terms of standard polystyrene measured using gel permeation chromatography (GPC).

[0033] The content of the thermoplastic resin (B-1) is 2% by mass or more and 30% by mass or less with respect to the total amount of the resin component (R) of the composition (M). If this content is 2% by mass or more, it is easy to suppress deformation such as warping that occurs in the cured product. If this content is 30% by mass or less, it is easy to improve the fluidity of the composition (M), and the composition (M) can suppress the bleed-out of the elastomer (B) during the curing reaction. This content is more preferably 5% by mass or more, and even more preferably 10% by mass or more. This content is more preferably 25% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less.

[0034] The viscosity of the thermoplastic resin (B-1) at 25°C is preferably 1,000 Pa·s or less. In this case, the fluidity of the composition (M) can be further improved. This viscosity is more preferably 500 Pa·s or less, even more preferably 300 Pa·s or less, and particularly preferably 100 Pa·s or less. Incidentally, from the viewpoint of suppressing the bleed-out of the elastomer (B) during the curing reaction, this viscosity is preferably 0.5 Pa·s or more.

[0035] The glass transition temperature of the thermoplastic resin (B-1) is preferably -10°C or lower. In this case, deformation such as warping occurring in the cured product can be suppressed. The glass transition temperature is more preferably -20°C or lower, and even more preferably -40°C or lower. Note that the glass transition temperature may be -120°C or higher, and may be -100°C or higher. In this case, the effects of the present disclosure are easily obtained.

[0036] In addition, the elastomer (B) may contain at least one selected from the group consisting of a polyester resin, a styrene resin, a silicone resin, a butadiene resin, a polycarbonate resin, etc., in addition to the polyester polyol resin and the (meth)acrylic resin.

[0037] (Magnetic filler) As described above, the composition (M) contains a magnetic filler (C). The magnetic filler (C) can improve the magnetic properties of the composition (M) and the cured product of the composition (M). The form of the magnetic filler (C) may be crystalline, amorphous, or nanocrystalline. Note that the nanocrystalline system is one in which a small crystal phase is partially precipitated in an amorphous matrix.

[0038] The magnetic filler (C) contains at least one selected from the group consisting of iron, an iron-based alloy, a ferrite-based alloy, and a cobalt-based alloy. The iron contains, for example, high-purity iron (pure iron) with a purity of 99.90 to 99.95%. Specifically, the iron contains at least one selected from the group consisting of, for example, carbonyl iron, Armco iron, sponge iron, and electrolytic iron.

[0039] Iron-based alloys include, for example, soft magnetic iron alloys. Soft magnetic iron alloys include, for example, iron (Fe)-silicon (Si) alloys, iron (Fe)-silicon (Si)-boron (B) alloys, iron (Fe)-nitrogen (N) alloys, iron (Fe)-carbon (C) alloys, iron (Fe)-boron (B) alloys, iron (Fe)-phosphorus (P) alloys, iron (Fe)-aluminum (Al) alloys, iron (Fe)-aluminum (Al)-silicon (Si) alloys, It includes at least one selected from the group consisting of permendur (Fe-Co), iron (Fe)-cobalt (Co)-vanadium (V) alloy, iron (Fe)-silicon (Si)-chromium (Cr) alloy, iron (Fe)-silicon (Si)-chromium (Cr)-boron (B) alloy, and iron (Fe)-silicon (Si)-niobium (Nb)-boron (B)-copper (Cu) alloy, etc.

[0040] The average particle size of the magnetic filler (C) is preferably 0.2 μm or more and 40.0 μm or less. If the average particle size is 0.2 μm or more, the permeability of the cured product can be easily increased. If the average particle size is 40.0 μm or less, the increase in the loss coefficient (μ'' / μ') of the cured product can be suppressed, and the attenuation of permeability in the high-frequency range can be suppressed. The average particle size refers to the particle size (50% particle diameter, median diameter) corresponding to 50% of the volume-based integrated value calculated from the measured particle size distribution by laser diffraction and scattering method.

[0041] The content of magnetic filler (C) is 85% by mass or more and 98% by mass or less, relative to the total amount of solids in composition (M). If the content is 85% by mass or more, the magnetic properties can be further improved. If the content is 98% by mass or less, the fluidity of composition (M) and the suppression of warping and other issues occurring in the cured product can be further improved. The content is more preferably 90% by mass or more, and even more preferably 93% by mass or more.

[0042] The magnetic filler (C) may contain only one type of filler, or it may contain two or more types of fillers. For example, the magnetic filler (C) may include a first magnetic filler (C-1) (hereinafter also referred to as the first magnetic filler (C-1)) with an average particle size greater than 3.0 μm and 40.0 μm or less, and a second magnetic filler (C-2) (hereinafter also referred to as the second magnetic filler (C-2)) with an average particle size of 0.1 μm or more and 3.0 μm or less. The average particle size of the first magnetic filler (C-1) is larger than the average particle size of the second magnetic filler (C-2). In this case, the magnetic properties of the composition (M) and the cured product can be further improved without impairing the fluidity of the composition (M). For example, the average particle size of the first magnetic filler (C-1) is about 10 times the average particle size of the second magnetic filler (C-2). The form of the first magnetic filler (C-1) may be, for example, crystalline or amorphous. In other words, the first magnetic filler (C-1) may include nanocrystals or amorphous alloys. The average particle size of the first magnetic filler (C-1) is more preferably 3.5 μm or larger, and even more preferably 5.0 μm or larger. The average particle size of the first magnetic filler (C-1) is more preferably 30 μm or smaller, and even more preferably 20 μm or smaller. The average particle size of the second magnetic filler (C-2) is more preferably 0.2 μm or larger. The average particle size of the second magnetic filler (C-2) is even more preferably 2.0 μm or smaller. Note that the average particle size of the first magnetic filler (C-1) and the average particle size of the second magnetic filler (C-2) refer to the particle size (50% particle diameter, median diameter) corresponding to 50% of the volume-based integrated value calculated from the measured particle size distribution by laser diffraction and scattering method.

[0043] The surface of the first magnetic filler (C-1) is preferably insulated. Insulation means forming a uniform insulating film with a thickness of about 1 nm to 50 nm on the surface of the metal filler. For example, the insulating film is formed by phosphate coating or silica coating with tetraethoxysilane, tetramethoxysilane, or sodium silicate. By forming an insulating film, even if the particles of the magnetic filler (C) are in contact with each other in the composition (M), the electrical conduction paths between the particles of the magnetic filler (C) are closed. This can increase the resistance of the composition (M). When the electrical resistance of the composition (M) increases, the magnetic loss term (μ'') decreases and the generation of eddy currents can be suppressed. As a result, a magnetic material with high efficiency and low heat generation can be obtained from the composition (M).

[0044] When the magnetic filler (C) includes a first magnetic filler (C-1) and a second magnetic filler (C-2), the mass ratio of the second magnetic filler (C-2) to the first magnetic filler (C-1) is preferably 1 / 1 or more and 20 / 1 or less. In this case, the viscosity of composition (M) is easily reduced, and the fluidity of composition (M) can be further improved. This ratio is more preferably 2 / 1 or more, and even more preferably 4 / 1 or more. This ratio is more preferably 20 / 1 or less, and even more preferably 10 / 1 or less.

[0045] (Additives) Composition (M) may further contain additive (D) in addition to the thermosetting resin (A), elastomer (B), and magnetic filler (C). Additive (D) is included in the resin component (R).

[0046] Additive (D) includes at least one selected from the group consisting of, for example, silane coupling agents, dispersants, leveling agents, adhesion promoters, and antistatic agents.

[0047] The silane coupling agent includes, for example, at least one selected from the group consisting of epoxy group-containing alkoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, mercapto group-containing alkoxysilane compounds such as γ-mercaptopropyltriethoxysilane, and amino group-containing alkoxysilane compounds such as γ-(2-aminoethyl)aminopropylmethyldimethoxysilane.

[0048] As a dispersant, various dispersants commonly used as dispersants can be used. The dispersant includes, for example, at least one selected from the group consisting of superbranched polyesters, hydroxyl group-containing carboxylic acid esters, alkylammonium salts of polymer copolymers, and phosphate ester salts.

[0049] (Solvent) Composition (M) may contain a solvent in addition to the thermosetting resin (A), elastomer (B), magnetic filler (C), and additive (D), from the viewpoint of ease of handling of composition (M). However, the solvent content is preferably 5% by mass or less, and more preferably 3% by mass or less, based on the total amount of composition (M).

[0050] (Non-magnetic filler) Composition (M) may contain a non-magnetic filler different from the magnetic filler (C). The non-magnetic filler preferably contains a metal oxide filler such as silica or alumina, and more preferably silica. By including a non-magnetic filler in composition (M), the coefficient of thermal expansion of the cured product of composition (M) can be reduced, and warping can be suppressed. The average particle size of the silica is preferably 0.1 μm or more and 1.0 μm or less. When such silica is used, the gaps that occur between the particles of the magnetic filler (C) can be filled with silica. This reduces the coefficient of thermal expansion of the cured product of composition (M), and thus reduces warping of the cured product. The average particle size of the non-magnetic filler, like that of the magnetic filler (C), refers to the particle size (50% particle diameter, median diameter) corresponding to 50% of the volume-based integrated value calculated from the measured particle size distribution by laser diffraction and scattering method.

[0051] The content of the non-magnetic filler is preferably 0.1% by mass or more and 5.0% by mass or less, relative to the total amount of solids in composition (M). Furthermore, while the shape of the non-magnetic filler is not particularly limited, it is preferably spherical or perfectly spherical. Such a shape allows for efficient filling of the gaps between the magnetic filler (C) particles.

[0052] 2.2 The properties of the characteristic composition (M) and its cured product will be described below. The following properties can be achieved by appropriately adjusting the composition of composition (M) within the range described above.

[0053] (Melting Viscosity) It is preferable that the melting viscosity of composition (M) is adjusted to a specific range. Specifically, it is preferable that the melting viscosity of composition (M) at 175°C is 5000 Pa·s or less. If this melting viscosity is within the above range, the fluidity of composition (M) can be improved. It is more preferable that this melting viscosity is 1000 Pa·s or less, and even more preferable that it is 500 Pa·s or less. From the viewpoint of handling, this melting viscosity may be 100 Pa·s or more. Note that melting viscosity refers to the viscosity of composition (M) when it is heated to a certain temperature and becomes molten.

[0054] (Magnetic Properties) Composition (M) and its cured product have enhanced magnetic properties, specifically permeability, due to the inclusion of a magnetic filler (C). However, if the magnetic filler content is too high, the fluidity of composition (M) deteriorates, and if a magnetic filler with a large average particle size is used, the loss coefficient (μ" / μ') increases. As a result, there is a risk of attenuation of permeability and an increase in the loss coefficient in the high-frequency range. Specifically, the permeability of the cured product of composition (M) at a frequency of 10 MHz is preferably 8 or higher, and more preferably 20 or higher. This allows molded products containing the cured product of composition (M) to exhibit high permeability. It is more preferable if the permeability of the cured product of composition (M) at a frequency of 10 MHz is 22 or higher. Furthermore, it is preferable that the loss coefficient of the cured product of composition (M) at a frequency of 10 MHz is 0.11 or less, and more preferably 0.06 or less.

[0055] Also, it is preferable that the permeability of the cured product of the composition (M) at a frequency of 100 MHz is 8 or more. Thereby, the molded product containing the cured product of the composition (M) can exhibit a higher permeability. Also, it is preferable that the loss factor of the cured product of the composition (M) at a frequency of 100 MHz is 0.06 or less.

[0056] Note that the permeability means the real part (μ ｒ ') of the complex relative permeability (μ ｒ ). The complex relative permeability (μ ｒ ) is represented by the formula μ ｒ = μ / μ ０ (μ: complex permeability, μ ０ : permeability of vacuum). The complex permeability (μ) is represented by the formula μ = μ' - iμ" (μ': real part, μ": imaginary part, i: imaginary unit). In the embodiment, "permeability" mainly means the real part (μ ｒ ') of the complex relative permeability (μ ｒ ). That is, the real part (μ ｒ ') of the complex relative permeability (μ ｒ ) is represented by the formula μ ｒ ' = μ' / μ ０ . The imaginary part (μ ｒ ") of the complex relative permeability (μ ｒ ) is represented by the formula μ ｒ " = μ" / μ ０ . Also, the loss factor (tanδ) is represented by the formula tanδ = μ ｒ " / μ ｒ ' = μ" / μ'. The relational expressions of the complex relative permeability (μ ｒ ) are summarized as follows.

[0057]

[0058] 3. Manufacturing method The composition (M) according to the embodiment can be manufactured by uniformly mixing raw materials including a thermosetting resin (A), an elastomer (B), a magnetic filler (C), etc. General mixers can be used for mixing the raw materials.

[0059] 4. By appropriately changing the form of the composition (M), it can be easily applied to various uses. For example, the composition (M) can be formed into a paste or a sheet and used. In other words, the magnetic paste according to the embodiment includes the composition (M). The magnetic sheet according to the embodiment includes the composition (M) or a semi-cured product of the composition (M). Here, a semi-cured product is a state in which the composition (M) has been partially cured to the extent that it can be further cured. For example, when the composition (M) according to the embodiment is heated, the viscosity gradually decreases at the beginning of heating, but as the curing of the composition (M) begins, the viscosity gradually increases. Thus, the semi-cured product is a state in which the composition (M) has been partially cured, and is what is called a B-staged composition (M).

[0060] Magnetic paste can be manufactured by adding other components in addition to those listed in "2.1 Composition" above, so that it can be applied to a variety of uses.

[0061] A magnetic sheet can be formed by applying composition (M) onto a support film. At this time, the composition (M) applied onto the support film may be heated and dried as necessary, such as to remove the solvent (E).

[0062] 5. The molded article according to the embodiment includes a cured product of composition (M). The cured product can impart excellent magnetic properties to the molded article. Furthermore, since deformation such as warping that occurs in the cured product is suppressed, there is an advantage in that the reliability of the molded article can be improved.

[0063] Examples of molded products include inductor components and inductors embedded in circuit boards.

[0064] An inductor component comprises a coil-shaped wiring and an insulating layer covering the coil-shaped wiring. The insulating layer includes a cured product of composition (M). Examples of inductor components include coils, inductors, filters, reactors, or transformers. The applications of inductor components are not particularly limited, but examples include noise filter components, impedance matching circuit components, and voltage conversion components. Examples of noise filters include low-pass filters and common-mode choke coils. Examples of voltage conversion components include DC-DC converters, AC-DC converters, and voltage regulators.

[0065] Furthermore, the substrate-embedded inductor comprises a substrate and an insulating layer. The insulating layer includes a cured product of composition (M). When manufacturing the substrate-embedded inductor, the insulating layer can be produced by applying composition (M) to the substrate, i.e., by applying a magnetic paste, or by forming composition (M) into a sheet and then placing a magnetic sheet. The substrate of the substrate-embedded inductor may have vias or through-holes, but because the fluidity of composition (M) is enhanced, it can efficiently fill vias or through-holes with composition (M). Also, the substrate of the substrate-embedded inductor may have bumps, but because the fluidity of composition (M) is enhanced, it can cover the bumps without gaps. Therefore, using composition (M) to produce the insulating layer has the advantage of making it less likely for voids to form in the insulating layer.

[0066] 6. Aspects As will be clear from the embodiments described above, the present disclosure includes the following aspects.

[0067] A composition (M) according to a first aspect of the present disclosure is a composition (M) comprising a thermosetting resin (A), an elastomer (B) containing a thermoplastic resin (B-1) that is liquid at 25°C, and a magnetic filler (C), wherein the thermoplastic resin (B-1) comprises at least one selected from the group consisting of polyester polyol resins and (meth)acrylic resins. The content of the elastomer (B) is 0.05% by mass or more and 1.50% by mass or less, based on the total amount of solids in the composition (M).

[0068] According to this embodiment, it is possible to simultaneously achieve improved magnetic properties, improved fluidity, and suppression of deformation such as warping that occurs in the cured product.

[0069] In the second aspect of the present disclosure, the composition (M) has, in the first aspect, a magnetic filler (C) content of 85% by mass or more and 98% by mass or less based on the total amount of solids in the composition (M).

[0070] In a third aspect of the present disclosure, the composition (M) is, in the first or second aspect, a thermoplastic resin (B-1) having a viscosity of 1000 Pa·s or less at 25°C.

[0071] In the composition (M) according to the fourth aspect of the present disclosure, in any one of the first to third aspects, the content of thermoplastic resin (B-1) is 2% by mass or more and 30% by mass or less, based on the total amount of resin component (R) of composition (M).

[0072] In the fifth aspect of the present disclosure, the composition (M) is characterized in that, in any one of the first to fourth aspects, the glass transition temperature of the thermoplastic resin (B-1) is -10°C or lower.

[0073] In the sixth aspect of the present disclosure, the composition (M) is, in any one of the first to fifth aspects, a thermoplastic resin (B-1) having a weight-average molecular weight of 1,000 or more and 9,000 or less.

[0074] A composition (M) according to a seventh aspect of the present disclosure, in any one of the first to sixth aspects, comprises an epoxy resin (A-1) as the thermosetting resin (A).

[0075] A composition (M) according to the eighth aspect of the present disclosure, in any one of the first to seventh aspects, comprises a magnetic filler (C) which includes a first magnetic filler (C-1). The first magnetic filler (C-1) comprises a nanocrystal or an amorphous alloy.

[0076] In the composition (M) according to the ninth aspect of the present disclosure, the surface of the first magnetic filler (C-1) is insulated in the eighth aspect.

[0077] A magnetic paste according to the tenth aspect of the present disclosure comprises a composition (M) according to any one of the first to ninth aspects.

[0078] A magnetic sheet according to the eleventh aspect of the present disclosure comprises a composition (M) or a semi-cured product of composition (M) according to any one of the first to ninth aspects.

[0079] A molded article according to a twelfth aspect of the present disclosure comprises a cured product of a composition (M) according to any one of the first to ninth aspects.

[0080] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to the following examples.

[0081] 1. After preparing the magnetic resin composition, the magnetic resin compositions of the examples and comparative examples were prepared by mixing the components shown in the table below. Details of the components shown in the table are as follows.

[0082] (Thermosetting resins) - Thermosetting resin #1: Bisphenol F type epoxy resin (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., product name YDF8170, viscosity at 25°C 1000-1500 mPa·s, epoxy equivalent 158 ​​g / eq.) - Thermosetting resin #2: Trifunctional epoxy compound (manufactured by Printec, Inc., product name VG3101L, epoxy equivalent 210 g / eq.) - Thermosetting resin #3: Polyfunctional solid epoxy resin (manufactured by Nippon Kayaku Co., Ltd., product name: NC3000) - Thermosetting resin #4: Dicyandiamide.

[0083] (Elastomer) - Elastomer #1: Liquid polyester polyol resin (manufactured by DIC Corporation, product name FPS-100, viscosity at 25°C 252.00 Pa·s, glass transition temperature -20°C, weight-average molecular weight 2000).

[0084] - Elastomer #2: Liquid polyester polyol resin (manufactured by DIC Corporation, product name FPS-120, viscosity at 25°C 0.95 Pa·s, glass transition temperature -67°C, weight-average molecular weight 2000).

[0085] - Elastomer #3: Liquid (meth)acrylic resin (manufactured by Toagosei Co., Ltd., product name ARUFON US6100, viscosity at 25°C 2.30 Pa·s, glass transition temperature -58°C, weight-average molecular weight 2500).

[0086] - Elastomer #4: Liquid (meth)acrylic resin (manufactured by Toagosei Co., Ltd., product name ARUFON UP1021, viscosity at 25°C 0.40 Pa·s, glass transition temperature -71°C, weight-average molecular weight 1600).

[0087] - Elastomer #5: Solid (meth)acrylic resin (manufactured by Kuraray Co., Ltd., product name Clarity LA2140, glass transition temperature -25°C, weight-average molecular weight tens of thousands to hundreds of thousands).

[0088] - Elastomer #6: Solid silicone resin (manufactured by Dow Chemical Co., Ltd., product name DOWSIL EP2601, glass transition temperature -100°C).

[0089] (Magnetic filler) - Magnetic filler #1: Iron (Fe)-Silicon (Si)-Niobium (Nb)-Boron (B)-Copper (Cu) alloy (average particle size 27 μm, nanocrystalline alloy, surface treated with phosphoric acid).

[0090] - Magnetic filler #2: Iron (Fe)-Silicon (Si)-Chromium (Cr)-Boron (B) alloy (average grain size 3 μm, amorphous alloy, surface treated with phosphoric acid).

[0091] (Additives) - Additive #1: Wetting and dispersing agent (manufactured by BIC Chemie Japan Co., Ltd., product name DISPERBY K-W9010).

[0092] 2. Preparation of Magnetic Sheets In each example and comparative example of the magnetic resin composition, the content of methyl ethyl ketone / N,N-dimethylformamide mixed solvent (mixing ratio 70 / 30) was adjusted to 3% of the total amount of the magnetic resin composition. Each adjusted magnetic resin composition was applied onto a PET film using a comma coater (Hirano Texseed Co., Ltd.), and a magnetic sheet with a thickness of 100 μm was prepared by drying at 120°C for 10 minutes.

[0093] 3. Evaluation The following evaluation tests were performed on the prepared magnetic sheets. The results are shown in the table below. (1) Melt viscosity at 175°C The melt viscosity of the magnetic sheet at 175°C was measured using a flow tester viscometer (Shimadzu Corporation, product name: CFT-500D). A die with a nozzle diameter of 1 mm and a nozzle length of 2 mm was used for the measurement.

[0094] In the case of Comparative Example 1, measurement was not possible because the melt viscosity value was too high.

[0095] (2) Warpage Amount A magnetic sheet was prepared and placed on a circular silicon wafer (dimensions 150 mmφ, thickness 525 mm) so that the side with the composition was in contact with the silicon wafer. Then, it was molded using a vacuum laminator manufactured by Nikko Material at a temperature of 100°C, a vacuum time of 60 seconds, a pressure of 0.7 MPa, and a molding time of 5 minutes. After molding, it was allowed to cool to room temperature, the PET film was peeled off, and it was cured in an oven at 100°C for 120 minutes, followed by curing at 175°C for 240 minutes. After curing, it was left at room temperature for 12 hours, and then the amount of warpage of the obtained magnetic sheet was measured. The measurement was taken with the orientation flat surface of the silicon wafer facing downwards, and four points on the top, bottom, left, and right of the circle were measured using a taper gauge or metal ruler. The average value of the four points was taken as the amount of warpage.

[0096] (3) Appearance after lamination The surface appearance of the cured magnetic sheet formed on the silicon wafer surface using the method described in "(2) Warpage" was observed and evaluated according to the following criteria.

[0097] A: No color unevenness due to phase separation of the elastomer during curing is observed. B: Color unevenness due to phase separation of the elastomer during curing is observed.

[0098] (4) Permeability and loss coefficient The prepared magnetic sheet was hardened by pressing to obtain a ring-shaped molded product (outer diameter 20 mm, inner diameter 9 mm, thickness 0.75 mm). The pressing conditions (temperature / pressure) were 175°C / 10 MPa for 20 minutes, followed by an additional curing at 175°C for 90 minutes. Subsequently, the permeability (complex ratio permeability (μ)) of the molded product at 10 MHz was measured using a Keysight Impedance / Material Analyzer, part number E4991B. ｒ The real part (μ) ｒ The ')) and loss factor (tanδ) were measured.

[0099]

[0100]

Claims

1. A magnetic resin composition comprising a thermosetting resin (A), an elastomer (B) containing a thermoplastic resin (B-1) that is liquid at 25°C, and a magnetic filler (C), wherein the thermoplastic resin (B-1) comprises at least one selected from the group consisting of polyester polyol resins and (meth)acrylic resins, and the content of the elastomer (B) is 0.05% by mass or more and 1.50% by mass or less with respect to the total amount of solids in the magnetic resin composition.

2. The magnetic resin composition according to claim 1, wherein the content of the magnetic filler (C) is 85% by mass or more and 98% by mass or less based on the total amount of solids in the magnetic resin composition.

3. The magnetic resin composition according to claim 1, wherein the viscosity of the thermoplastic resin (B-1) at 25°C is 1000 Pa·s or less.

4. The magnetic resin composition according to claim 1, wherein the content of the thermoplastic resin (B-1) is 2% by mass or more and 30% by mass or less, based on the total amount of resin components of the magnetic resin composition.

5. The magnetic resin composition according to claim 1, wherein the glass transition temperature of the thermoplastic resin (B-1) is -10°C or lower.

6. The magnetic resin composition according to claim 1, wherein the weight-average molecular weight of the thermoplastic resin (B-1) is 1,000 or more and 9,000 or less.

7. The magnetic resin composition according to claim 1, wherein the thermosetting resin (A) comprises an epoxy resin (A-1).

8. The magnetic resin composition according to claim 1, wherein the magnetic filler (C) comprises a first magnetic filler (C-1) having a volume-based cumulative 50% particle size (D50) of 2.0 μm or more and 40.0 μm or less in the particle size distribution, and the first magnetic filler (C-1) comprises nanocrystals or amorphous alloys.

9. The magnetic resin composition according to claim 8, wherein the surface of the first magnetic filler (C-1) is insulated.

10. A magnetic paste comprising the magnetic resin composition according to any one of claims 1 to 9.

11. A magnetic sheet comprising a magnetic resin composition according to any one of claims 1 to 9 or a semi-cured product of the magnetic resin composition.

12. A molded article comprising a cured product of the magnetic resin composition according to any one of claims 1 to 9.

Images