Magnetic body-containing resin composition, magnetic body-containing resin sheet, and cured body

Abstract

[Problem] To solve a problem wherein it is necessary to compound with a large amount of magnetic powder in order to increase magnetic permeability, but it is difficult to obtain stable production.　[Solution] Provided are a magnetic body-containing resin composition, a magnetic body-containing resin sheet, and a cured body that contain 100 parts by mass of (a) an organopolysiloxane, 500-900 parts by mass of (b) a soft magnetic body, 1-5 parts by weight of (c) an alkoxysilane, and (d) a curing agent required to cure the organopolysiloxane.

Description

Magnetic material-containing resin composition, magnetic material-containing resin sheet, and cured product

[0001] The present invention relates to a magnetic material-containing resin composition, a magnetic material-containing resin sheet, and a cured product.

[0002] With the spread of electric vehicles and plug-in hybrid vehicles, research and development into wireless power transfer systems that are easy to operate and have low maintenance costs is progressing. While electric field coupling in the 400 kHz band and magnetic field coupling in the 6.7 MHz band are used for low-power applications such as mobile devices, magnetic field coupling in the 85 kHz band (79-90 kHz) is used for electric vehicles.

[0003] In recent years, magnetic resonance methods that utilize the resonance conditions of coils have been attracting attention. It has been agreed that the international 85 kHz band will be the operating frequency band for power supply systems for electric vehicles. Wireless power transfer uses the magnetic field generated by the coil to transmit power. However, this magnetic field generates eddy currents in nearby metals, leading to loss of transmitted power and heat generation. To prevent this, it is common to place a magnetic material with high magnetic permeability and low conductivity around the coil.

[0004] Known electromagnetic wave absorbers using such soft magnetic sheets include those containing soft ferrite, flat soft magnetic metal powder, magnetite, and silicone gel (see, for example, Patent Document 1). Also known is a coil module that includes a magnetic shield layer having a magnetic resin layer containing magnetic particles and a spiral coil, with at least a portion of the spiral coil embedded in the magnetic resin layer (see, for example, Patent Document 2).

[0005] JP 2005-286193 A JP 2014-027094 A

[0006] However, the above-mentioned conventionally known wireless power supply systems have the following problems. The electromagnetic wave absorber disclosed in Patent Document 1 is a technology that excels particularly in the high-frequency range but is not suitable for the long-wave range. Furthermore, the module disclosed in Patent Document 2 has a problem in that cracks occur in the magnetic sheet made of hard ferrite when the receiving unit is bent and mounted. In other words, to increase magnetic permeability, it is necessary to incorporate a large amount of magnetic powder, but stable production has been difficult.

[0007] An object of the present invention is to solve the above problems, that is, to stably produce a magnetic-substance-containing resin sheet and a cured product thereof that are suitable for long-waveband characteristics and have rubber elasticity.

[0008] (1) To achieve the above object, a magnetic material-containing resin composition according to one embodiment comprises 100 parts by mass of (a) organopolysiloxane, 500 to 900 parts by mass of (b) soft magnetic material, 1 to 5 parts by weight of (c) alkoxysilane, and (d) a curing agent required for curing the organopolysiloxane. (2) A magnetic material-containing resin composition according to another embodiment may preferably further comprise 1 to 33 parts by weight of (e) silica. (3) In a magnetic material-containing resin composition according to another embodiment, the (c) alkoxysilane may preferably be one having the following structural formula: R-Si(OR' ３) (R: C4 or larger alkyl group, R': C1 to C3 alkyl group) (4) In a magnetic material-containing resin composition according to another embodiment, preferably, (c) the alkoxysilane may be a one-terminal trimethoxy-modified silane or decyltrimethoxysilane. (5) In a magnetic material-containing resin composition according to another embodiment, preferably, (b) the soft magnetic material may be an Mn-Zn or Mn-Mg-Zn soft magnetic powder. (6) In a magnetic material-containing resin composition according to another embodiment, preferably, the volume ratio of (b) the soft magnetic material to the magnetic material-containing resin composition may be 48 to 65 vol%. (7) A magnetic material-containing resin sheet according to an embodiment for achieving the above object is a sheet-shaped cured product of any of the magnetic material-containing resin compositions described above. (8) In a magnetic material-containing resin sheet according to another embodiment, preferably, the magnetic permeability (μ') at a frequency of 85 kHz may be 8 or greater. (9) In a cured product according to an embodiment for achieving the above object, the cured product is any of the magnetic material-containing resin compositions described above. (10) In the magnetic body according to another embodiment, it may preferably be a case in which a coil is disposed.

[0009] According to the present invention, it is possible to provide a magnetic material-containing resin sheet and a cured product thereof that contain a magnetic material and have high flexibility and do not require surface treatment.

[0010] Next, an embodiment of the present invention will be described. Note that the embodiment described below does not limit the invention according to the claims, and not all of the elements and combinations thereof described in the embodiment are necessarily essential to the solution of the present invention.

[0011] 1. Magnetic Material-Containing Resin Composition A magnetic material-containing resin composition according to one embodiment of the present invention contains (a) an organopolysiloxane, (b) a soft magnetic material, (c) an alkoxysilane, and (d) a curing agent. The magnetic material-containing resin composition may preferably further contain (e) silica. Below, the components (a) to (e) and (f) other components will be mainly described.

[0012] (a) Organopolysiloxane Examples of organopolysiloxanes include organopolysiloxanes represented by the following average composition formula (1). There are no particular restrictions on the average degree of polymerization of the organopolysiloxane, but it is preferably 3,000 to 12,000. When the average degree of polymerization is 3,000 or more and 12,000 or less, blending workability is good and the dispersibility of additives can be improved. R ｎ SiO （４－ｎ）／２ ...(1) [R represents an optionally substituted monovalent hydrocarbon group. The hydrocarbon group preferably has 1 or more and 12 or less carbon atoms, more preferably 1 or more and 8 or less carbon atoms. Multiple Rs may be the same or different. n represents a number of 1.95 or more and 2.05 or less.]

[0013] Examples of R in the above formula (1) include alkyl groups such as a methyl group, ethyl group, propyl group, butyl group, hexyl group, and dodecyl group; cycloalkyl groups such as a cyclohexyl group; alkenyl groups such as a vinyl group, allyl group, butenyl group, and hexenyl group; aryl groups such as a phenyl group and tolyl group; aralkyl groups such as a β-phenylpropyl group; and organic groups in which some or all of the hydrogen atoms bonded to carbon atoms of the above groups have been substituted with halogen atoms, cyano groups, or the like, such as a chloromethyl group, a trifluoropropyl group, and a cyanoethyl group.

[0014] The organopolysiloxane is preferably an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule. For example, in the above formula (1), at least two R's are preferably alkenyl groups. The organopolysiloxane more preferably contains vinyl groups.

[0015] Specific examples of organopolysiloxanes include dimethylpolysiloxane and diphenylpolysiloxane. The molecular chain terminals of the organopolysiloxane are preferably blocked with trimethylsilyl groups, dimethylvinylsilyl groups, dimethylhydroxysilyl groups, trivinylsilyl groups, etc. One type of organopolysiloxane may be used alone, or two or more types differing in molecular structure, degree of polymerization, etc. may be used in combination.

[0016] (b) Soft Magnetic Material Examples of soft magnetic materials include soft iron, electromagnetic steel, permalloy, and soft ferrite. Examples of soft ferrite include soft magnetic powders such as Fe—Cr, Fe—Si, Fe—Ni, Fe—Al, Fe—Co, Fe—Al—Si, Fe—Cr—Si, Fe—Si—Ni, Ni—Zn, Mn—Zn, Cu—Zn, and Mn—Mg—Zn. The soft magnetic powders may be surface-treated. The soft magnetic powders may be used alone or in combination of two or more. For use in the long-wave band (30 to 300 kHz), Mn—Zn and / or Mn—Mg—Zn soft magnetic powders are particularly preferred.

[0017] The content of the soft magnetic material is preferably 500 to 900 parts by weight (500 parts by weight or more and 900 parts by weight or less) per 100 parts by weight of the organopolysiloxane. When the magnetic-material-containing resin composition contains 500 parts by weight or more of the soft magnetic material, the magnetic permeability of the magnetic-material-containing resin sheet molded from the magnetic-material-containing resin composition can be further increased. On the other hand, when the magnetic-material-containing resin composition contains 900 parts by weight or less of the soft magnetic material, kneading with the organopolysiloxane becomes easy. However, when an organic solvent such as toluene is added to the magnetic-material-containing resin composition to form a paste and then coated on a release film, the amount of the soft magnetic material blended into the magnetic-material-containing resin composition can be increased up to 1,200 parts by weight per 100 parts by weight of the organopolysiloxane.

[0018] By increasing the amount of soft magnetic material, it is possible to improve the magnetic permeability of the magnetic material-containing resin sheet, but this reduces the processability when processing the magnetic material-containing resin composition into a magnetic material-containing resin sheet. To obtain a magnetic permeability (μ'): 8 required in the market, it is sufficient to compound 500 parts by weight or more and 800 parts by weight or less of soft magnetic material with 100 parts by weight of organopolysiloxane.

[0019] The volume ratio of the soft magnetic material in the magnetic material-containing resin composition is preferably 48 to 65% by volume (48% by volume or more and 65% by volume or less).

[0020] The average particle size of the soft magnetic powder is preferably 0.1 μm or more and 50 μm or less, more preferably 1 μm or more and 20 μm or less. Furthermore, by selecting and blending two or more soft magnetic powders with different peaks (most common particle sizes) in the particle size distribution, it becomes easier to achieve high loading of the soft magnetic powder. Note that the "average particle size" in this application refers to the average particle size obtained by laser diffraction particle size distribution measurement.

[0021] (c) Alkoxysilane Alkoxysilane is a component (also referred to as a material) necessary for improving the affinity between the soft magnetic material and the organopolysiloxane and for filling them uniformly and in large quantities.

[0022] Examples of alkoxysilanes include methyldimethoxysilane, dimethoxysilane, diethoxymethylsilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, hexyltriethoxysilane, tetramethoxysilane, and tetrapropoxysilane.

[0023] The alkoxysilane preferably has the following structural formula (2): R—Si(OR′ ３ ) (2) [R: an alkyl group having 4 or more carbon atoms (C4), R': an alkyl group having 1 to 3 carbon atoms (C1 to C3)] R' is more preferably a methoxy group.

[0024] The alkoxysilane is preferably a silicone compound having a hydrolyzable silyl group at one end of a hydrophobic group, such as a trimethoxy-modified silane or decyltrimethoxysilane.

[0025] The content of alkoxysilane is preferably 1 to 5 parts by weight (1 part by weight or more and 5 parts by weight or less) per 100 parts by weight of organopolysiloxane. When 1 part by weight or more of alkoxysilane is added to 100 parts by weight of organopolysiloxane, it is easy to knead the soft magnetic material into the organopolysiloxane, and it is easy to obtain a magnetic-substance-containing resin sheet that maintains sufficient elasticity and softness. Furthermore, when 5 parts by weight or less of alkoxysilane is added to 100 parts by weight of organopolysiloxane, it is possible to reduce the amount of alkoxysilane that is released from the magnetic-substance-containing resin sheet, which is more than enough to improve the affinity between the soft magnetic material and the organopolysiloxane. This reduces the risk of contaminating other parts that come into contact with the sheet and the risk of altering the properties and characteristics of the magnetic-substance-containing resin sheet itself from its initial state.

[0026] (d) Curing Agent Any curing agent (also called a crosslinking agent) can be used without particular restrictions, as long as it is capable of crosslinking the organopolysiloxane to cure the silicone composition. Examples of curing agents include peroxide-based crosslinking agents and addition reaction-based crosslinking agents.

[0027] Examples of peroxide-based crosslinking agents include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-bis(2,5-t-butylperoxy)hexane, di-t-butyl peroxide, t-butyl perbenzoate, and 1,6-hexanediol-bis-t-butylperoxycarbonate. An example of an addition reaction-based crosslinking agent is hydrogenated organopolysiloxane. Examples of organic groups bonded to silicon in hydrogenated organopolysiloxane include alkyl groups (methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.), aryl groups (phenyl, tolyl, xylyl, etc.), and halogenated alkyl groups (3-chloropropyl, 3,3,3-trifluoropropyl, etc.). Of the above organic groups, methyl groups are preferred. Examples of the molecular structure of this component include straight chain, partially branched straight chain, branched chain, network, and dendritic.

[0028] Examples of hydrogenated organopolysiloxanes include polydimethylsiloxanes terminated at both molecular chain terminals with dimethylhydrogensiloxy groups, polymethylhydrogensiloxanes terminated at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminated at both molecular chain terminals with trimethylsiloxy groups, cyclic polymethylhydrogensiloxanes, (CH ３ ) ２ HSiO １／２ and a siloxane unit represented by SiO ４／２ and organopolysiloxanes in which at least a portion of the methyl groups of these organopolysiloxanes have been substituted with alkyl groups (e.g., ethyl groups, propyl groups), aryl groups (e.g., phenyl groups, tolyl groups), or halogenated alkyl groups (e.g., 3,3,3-trifluoropropyl groups), as well as mixtures of two or more of these organopolysiloxanes.

[0029] (e) Silica Silica is not an essential compounding material for the magnetic material-containing resin composition according to this embodiment, but is a compounding material that is preferably added. By adding silica to the magnetic material-containing resin composition, the magnetic material-containing resin sheet can be given appropriate hardness and mechanical strength such as tensile strength. As the silica, a silica having a specific surface area of ​​at least 50 m is preferable. ２ / g or more, especially 100 to 400m ２ / g of silica powder can be used. Examples of such silica include fumed silica, calcined silica, precipitated silica, etc. These silicas can be used alone or in combination of two or more.

[0030] These silicas may also be surface-treated with reactive organosilicon compounds such as linear organopolysiloxanes, cyclic organopolysiloxanes, hexamethyldisilazane, and dichlorodimethylsilane. Such silica is blended in an amount of 33 parts by weight or less, particularly 5 parts by weight or less, per 100 parts by weight of organopolysiloxane. When the amount of silica blended is 33 parts by weight or less, the compound of the magnetic material-containing resin composition can be prevented from becoming excessively hard, thereby improving the flowability of the compound during molding.

[0031] (f) Other Components Examples of other components that can be added to the above (a) to (e) include auxiliaries (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardancy improvers, thermal conductivity improvers, release agents, solvents, etc.

[0032] 2. Magnetic Material-Containing Resin Sheet A magnetic material-containing resin sheet according to one embodiment of the present invention is a sheet-shaped cured product of the magnetic material-containing resin composition described above. Next, a method for producing the magnetic material-containing resin sheet will be exemplified.

[0033] The magnetic-material-containing resin composition containing the above-mentioned (a) to (d), preferably (e) and / or (f), is converted into a soft-magnetic-material-containing silicone composition using, for example, a kneader. There are no particular restrictions on the kneader, and a two-roll kneader is an example. After dispensing, the soft-magnetic-material-containing silicone composition is molded. There are no particular restrictions on the molding method, and mold molding is an example. Another example of a molding method is a method involving heating. Taking into consideration the curing of the organopolysiloxane, a temperature in the range of 170 to 200°C is preferred as the heating temperature during molding. In the case of mold molding, a magnetic-material-containing resin sheet can be produced by using a mold with an internal space capable of obtaining a sheet-shaped molded product. Further heating may be performed after molding. The temperature during further heating is preferably higher than the molding temperature, and is preferably in the range of 190 to 220°C.

[0034] The magnetic permeability (μ′) of the magnetic material-containing resin sheet is preferably 8 or more at a frequency of 85 kHz. For measuring the magnetic permeability, for example, an impedance analyzer E4990A and a measuring jig 16454A manufactured by Keysight Corporation can be used. The measurement is preferably performed in an environment of 25° C. with the measurement frequency set to 85 kHz.

[0035] 3. Cured Product A cured product according to one embodiment of the present invention is a cured product of the magnetic material-containing resin composition described above. The cured product is, for example, a case in which a coil is placed. For example, the coil can be one that enables contactless charging.

[0036] Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

[0037] Example 1 100 parts by weight of organopolysiloxane (methylvinylpolysiloxane, product number: KE-78VBS, manufactured by Shin-Etsu Chemical Co., Ltd.), 500 parts by weight of Mn—Zn-based soft magnetic powder (product number: BSF-547, manufactured by Toda Kogyo Co., Ltd.), 2 parts by weight of 2.5 dimethyl-2.5 bis(tertiarybutylperoxy)hexane (product number: C-8, manufactured by Shin-Etsu Chemical Co., Ltd.) as a crosslinking agent, and 1 part by mass of one-end trimethoxy-modified silane (product number: X-24-9011, manufactured by Shin-Etsu Chemical Co., Ltd.) as an alkoxysilane were kneaded and blended in a kneader mixer, and further kneaded with a two-roll mill to improve dispersibility, thereby blending a soft magnetic material-containing silicone composition. Next, the blended soft magnetic material-containing silicone composition was dispensed and then placed in a frame measuring 150 mm × 210 mm and 3.0 mm thick, and pressure-molded in a sheet molding die at 180°C for 5 minutes. Next, the pressure-molded soft magnetic material-containing silicone rubber sheet was placed in a gear oven and heated at 200°C for 4 hours. The specific gravity and magnetic permeability of the completed soft magnetic material-containing silicone rubber sheet were measured. The magnetic permeability measurement was performed using an impedance analyzer E4990A and a measuring jig 16454A manufactured by Keysight Technologies, Inc., at a measurement frequency of 85 kHz and an environment of 25°C. For the measurement, the magnetic resin sheet was punched into a ring-shaped sample having a thickness of 3 mm, an outer diameter of 30 mm, and an inner diameter of 20 mm.

[0038] (Example 2) A sheet was produced under the same conditions as in Example 1, except that 900 parts by weight of Mn-Zn based soft magnetic powder (product number: BSF-547, manufactured by Toda Kogyo Co., Ltd.) was used, and 5 parts by weight of decyltrimethoxysilane (product number: KBM-3103C, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the alkoxysilane, and measurements similar to those in Example 1 were carried out.

[0039] (Example 3) A sheet was manufactured under the same conditions as in Example 1, except that the soft magnetic powder was changed to 773 parts by weight of Mn-Mg-Zn based soft magnetic powder (product number: FRX-843, manufactured by Toda Kogyo Co., Ltd.) and 3 parts by weight of decyltrimethoxysilane (product number: KBM-3103C, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the alkoxysilane, and measurements similar to those in Example 1 were carried out.

[0040] (Example 4) A sheet was manufactured under the same conditions as in Example 3, except that 300 parts by weight of Mn-Zn based soft magnetic powder (product number: BSF-547, manufactured by Toda Kogyo Co., Ltd.) and 360 parts by weight of Mn-Mg-Zn based soft magnetic powder (product number: FRX-843, manufactured by Toda Kogyo Co., Ltd.) were used as the soft magnetic powder, and measurements similar to those in Example 1 were carried out.

[0041] (Example 5) As the soft magnetic powder, 773 parts by weight of Mn-Zn based soft magnetic powder (product number: BSF-547, manufactured by Toda Kogyo Co., Ltd.) was used, and 1 part by weight of silica (product name: Aerosil R-972, manufactured by Nippon Aerosil Co., Ltd.) was added. The conditions were the same as in Example 3, except that a sheet was produced, and measurements similar to those in Example 1 were carried out.

[0042] (Example 6) The silica (trade name: Aerosil R-972, manufactured by Nippon Aerosil Co., Ltd.) was changed to 33 parts by weight, and the alkoxysilane was changed to 5 parts by weight of decyltrimethoxysilane (product number: KBM-3103C, manufactured by Shin-Etsu Chemical Co., Ltd.). The conditions were the same as those in Example 5, except that a sheet was produced, and measurements similar to those in Example 1 were carried out.

[0043] Comparative Example 1 A sheet was produced under the same conditions as in Example 6, except that no alkoxysilane was added, and measurements similar to those in Example 1 were carried out.

[0044] Table 1 shows the manufacturing conditions and measurement results for Examples 1 to 6 and Comparative Example 1.

[0045]

[0046] The sheets obtained under the conditions of each example were crack-free and flexible. On the other hand, the sheets obtained under the conditions of Comparative Example 1, which did not contain alkoxysilane, were prone to cracking and difficult to dispense at a constant thickness. For this reason, continuous production of the sheets obtained under the conditions of Comparative Example 1 was not possible.

[0047] The present invention can be used in, for example, a wireless charging system.

Claims

1. A magnetic material-containing resin composition comprising: 100 parts by mass of (a) organopolysiloxane having an average degree of polymerization of 3,000 to 12,000; 500 to 900 parts by mass of (b) soft magnetic material; 1 to 5 parts by weight of (c) alkoxysilane; and (d) a curing agent necessary for curing the organopolysiloxane.

2. The magnetic material-containing resin composition according to claim 1 further contains 1 to 33 parts by weight of (e) silica.

3. In the magnetic material-containing resin composition according to claim 1 or 2, (c) the alkoxysilane has the following structural formula: R-Si(OR' ３ ) (R: C4 or higher alkyl group, R': C1 to C3 alkyl group) 4. In the magnetic material-containing resin composition according to claim 3, (c) the alkoxysilane is a silane modified with one end trimethoxy or decyltrimethoxysilane.

5. A magnetic material-containing resin composition according to any one of claims 1 to 4, wherein (b) the soft magnetic material is an Mn-Zn based soft magnetic powder or an Mn-Mg-Zn based soft magnetic powder.

6. A magnetic material-containing resin composition according to any one of claims 1 to 5, wherein (b) the volume ratio of the soft magnetic material to the magnetic material-containing resin composition is 48 to 65 vol %.

7. A magnetic material-containing resin sheet which is a sheet-shaped cured product of the magnetic material-containing resin composition according to any one of claims 1 to 6.

8. The magnetic material-containing resin sheet according to claim 7 has a magnetic permeability (μ') of 8 or more at a frequency of 85 kHz.

9. A cured product of the magnetic material-containing resin composition according to any one of claims 1 to 6.

10. The hardened body of claim 9, wherein the hardened body is a case for arranging a coil.

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