Noise suppression member

Abstract

Provided is a noise suppression member which exhibits excellent magnetic characteristics and in which the amount of flat magnetic powder blended is greater than that of conventional products. The noise suppression member is provided with a composite composition containing flat magnetic powder and a binder. The content of the flat magnetic powder is 88.9% by mass to 90% by mass with respect to 100% by mass of the composite composition. The adhesive contains a hydrogenated nitrile rubber and a polyolefin. The content of the hydrogenated nitrile rubber is 2 mass% to 9 mass% with respect to 100 mass% of the composite composition. The content of the polyolefin is 1% by mass to 8% by mass with respect to 100% by mass of the composite composition.

Description

Technical Field

[0001] The present disclosure relates to noise suppression components. Background Art

[0002] A composite magnetic sheet has been proposed that includes an organic binder and flat magnetic powder dispersed within the organic binder (see, for example, Patent Document 1). According to Patent Document 1, the composite magnetic sheet described in Patent Document 1 can suppress noise exceeding the UHF (Ultra High Frequency) band, for example, noise exceeding 5 GHz.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6405355 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In the composite magnetic sheet disclosed in Patent Document 1, the volume occupancy of the magnetic flat powder in the composite magnetic sheet is 40 vol% to 50 vol%, preferably 45 vol% to 50 vol%. In the composite magnetic sheet of Patent Document 1, a volume occupancy exceeding 50 vol% can lead to degradation of the film quality, reduced flexibility, and decreased surface resistivity of the composite magnetic sheet. Therefore, the volume occupancy is set to 50 vol% or less.

[0008] However, further research by the inventors of this application has led to the discovery that by selecting a specific binder, it is possible to blend magnetic powder in amounts exceeding 50 vol% without compromising the physical properties and processability of the sheet material. Furthermore, they discovered that within the range where the magnetic powder content exceeds 50 vol%, there exists a range of values ​​where the magnetic properties are specifically improved compared to when the magnetic powder content is 50 vol% or less. The technology described below is based on this knowledge.

[0009] One aspect of the present disclosure is to provide a noise suppression member that has a larger compounding amount of flat magnetic powder than existing products and exhibits excellent magnetic characteristics.

[0010] Solutions for solving problems

[0011] Hereinafter, the configuration of the present disclosure will be described.

[0012] (1) One embodiment of the present disclosure is a noise suppression component comprising a composite composition containing flat magnetic powder and a binder. The flat magnetic powder is an alloy powder selected from any one of Fe-Si-Cr alloy, Fe-Si alloy and Fe-Cr alloy, or a mixture of two or more alloy powders. The median particle size of the flat magnetic powder is 10 μm to 30 μm. The content of the flat magnetic powder is 88.9% to 90% by mass relative to 100% by mass of the composite composition. The binder contains hydrogenated nitrile rubber and polyolefin. The content of the hydrogenated nitrile rubber is 2% to 9% by mass relative to 100% by mass of the composite composition. The content of the polyolefin is 1% to 8% by mass relative to 100% by mass of the composite composition.

[0013] In a noise suppression component, when the flat magnetic powder content is adjusted to within a range of 88.9% to 90% by mass, the magnetic permeability of the noise suppression component is specifically improved, as illustrated in the specific examples in the embodiments described below. Furthermore, by setting the hydrogenated nitrile rubber content to 2% or more by mass, the sheet tensile strength required for the manufacturing process can be achieved. By setting the hydrogenated nitrile rubber content to 9% or less by mass, strong rebound during the separation and calendering processes can be suppressed, allowing the sheet to be stretched to an appropriate thickness.

[0014] Furthermore, by setting the polyolefin content in the noise suppression member to 1% by mass or greater, strong springback during the separation and calendering steps can be suppressed, allowing the sheet to be stretched to an appropriate thickness. Furthermore, by setting the polyolefin content in the noise suppression member to 8% by mass or less, adhesion of the sheet to the rollers during heat calendering can be suppressed, resulting in stable sheet production.

[0015] The noise suppression component thus constructed comprises a composite composition containing flat magnetic powder and a binder comprising hydrogenated nitrile rubber and polyolefin mixed in the aforementioned composition ratio. Therefore, unlike conventional techniques where the volume fraction of magnetic powder must be 50 vol% or less, the composite composition can contain magnetic powder in an amount exceeding 50 vol%.

[0016] More specifically, in the present disclosure, the flat magnetic powder is a powder of one alloy selected from Fe-Si-Cr alloys, Fe-Si alloys, and Fe-Cr alloys, or a mixture of two or more alloy powders. The flat magnetic powder has a median particle size of 10 μm to 30 μm. The content of the flat magnetic powder is 88.9% to 90% by mass relative to 100% by mass of the composite composition.

[0017] This mass ratio of 88.9% to 90% by mass corresponds to a volume occupancy of 52.5% to 54.5% by volume in the context of the present disclosure. In other words, the composite composition constituting the noise suppression member contains more than 50% by volume of magnetic powder. However, as described above, since the binder contains hydrogenated nitrile rubber and polyolefin mixed in the aforementioned composition ratio, even when the composite composition is processed into a sheet, degradation of the sheet's physical properties and processability can be minimized.

[0018] Furthermore, when the flat magnetic powder content in the noise suppression member is adjusted to the aforementioned range of 88.9% to 90% by mass, a noise suppression member exhibiting high magnetic permeability in the high-frequency band of 3 GHz to 6 GHz can be formed. The relationship between the flat magnetic powder content and magnetic permeability will be described in detail in the embodiments described below.

[0019] It should be noted that the present disclosure also has the following configurations.

[0020] (2) In one embodiment of the present disclosure, the content of the flat magnetic powder may be 89.2% by mass to 89.5% by mass relative to 100% by mass of the composite composition.

[0021] According to this configuration, a noise suppression member can be configured that exhibits high magnetic permeability in a high frequency band of 3 GHz to 6 GHz.

[0022] (3) In one aspect of the present disclosure, the noise suppression member may be formed in a sheet shape having a thickness of 0.3 mm to 0.5 mm.

[0023] (4) In one aspect of the present disclosure, the noise suppression member may have a complex magnetic permeability μ' (real part) of 1 or more in a frequency band of 3 GHz to 6 GHz.

[0024] (5) In one embodiment of the present disclosure, the surface resistance of the noise suppression member may be 1×10 6 Ω / □(Ω / sq) or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a graph showing the relationship between the content of flat magnetic powder and the measured value of the complex magnetic permeability μ' (real part) of the noise suppression member at a frequency of 6 GHz.

[0026] Figure 2 This is a graph showing measured values ​​of the complex magnetic permeability μ' (real part) and the complex magnetic permeability μ" (imaginary part) of the noise suppression member in the frequency band of 0.1 GHz to 6 GHz. DETAILED DESCRIPTION

[0027] Next, the above-mentioned noise suppression member will be described with reference to exemplary embodiments.

[0028] [Manufacturing Example of Noise Suppression Member]

[0029] Noise suppression members (Sample 1 to Sample 7) were produced according to the procedure described below.

[0030] First, hydrogenated nitrile rubber, polyolefin, and lubricant were weighed to the mass ratios shown in Table 1 and kneaded in a kneader to prepare an adhesive composition. Next, flat magnetic powder was weighed to the mass ratios shown in Table 1, and the flat magnetic powder and the adhesive composition were kneaded in a kneader. When kneading the flat magnetic powder and adhesive composition, the materials were preheated and kneaded at a temperature of 70°C to 90°C.

[0031] The flat magnetic powder is any alloy powder selected from the group consisting of Fe-Si-Cr alloy, Fe-Si alloy, and Fe-Cr alloy, or a mixture of two or more alloy powders. The flat magnetic powder has a median particle size of 10 μm to 30 μm. The flat magnetic powder has an aspect ratio of 10 to 40. It should be noted that the aspect ratio in this embodiment is the value obtained by dividing the long diameter dimension of the flat magnetic powder by the thickness dimension of the flat magnetic powder.

[0032] Next, since the material kneaded in the kneader contains some agglomerated parts, it is crushed so that the particles contained in the material are of roughly the same size. Next, separation is carried out using separation rolls heated to approximately 40°C to 60°C. The separated material is then rolled using calender rolls heated to approximately 40°C to 60°C, forming it into a sheet with a thickness of approximately 0.3mm to 0.5mm.

[0033] Next, the rolled sheet was cut into long strips and vacuum pressed for 5 minutes at 150° C. This vacuum pressing promoted degassing from the sheet, thereby increasing the density of the sheet and promoting crosslinking in the material.

[0034] [Table 1]

[0035]

[0036] [Performance test]

[0037] The following performance tests were performed on the above-mentioned samples 1 to 7.

[0038] The above-mentioned samples 1 to 7 were used as measurement objects to measure the complex magnetic permeability. In the measurement, a commercially available RF impedance analyzer (manufactured by Agilent Technologies, E4991A) was used. When performing the measurement, a ring-shaped measurement sample with an outer diameter of 18 mm and an inner diameter of 6 mm was cut out from the sample for measurement. As the measurement condition for measuring the complex magnetic permeability, the measurement frequency was set to 0.1 GHz to 6 GHz. The relationship between the content of flat magnetic powder and the measured value of the complex magnetic permeability μ' (real part) of the noise suppression component at a frequency of 6 GHz is shown in FIG. Figure 1 and Table 2.

[0039] [Table 2]

[0040] Sample No. 1 2 3 4 5 6 7 μ' / 6GHz 0.8 0.9 1.5 2.1 2.0 1.0 -0.3 Remark Comparative Example Comparative Example Example Example Example Example Comparative Example

[0041] according to Figure 1 As shown in Table 2, the complex magnetic permeability μ' (real part) values ​​for Samples 3-6 were 1 or greater, indicating their effectiveness as noise suppression components. In particular, the complex magnetic permeability μ' (real part) values ​​for Samples 4 and 5 were 2 or greater, demonstrating excellent noise suppression performance. The flat magnetic powder content in Samples 3-6 ranged from 88.9% to 90% by mass, equivalent to a volume occupancy of 52.5% to 54.5% by volume.

[0042] That is, the composite compositions constituting Samples 3 through 6 contain more than 50 vol% of flat magnetic powder. However, as described above, since the binder contains hydrogenated nitrile rubber and polyolefin blended in the aforementioned composition ratio, even when the composite compositions are processed into sheets, degradation of the sheet's physical properties and processability is minimized.

[0043] Next, for Sample 4, which had the highest value of complex permeability μ' (real part) in the above test, the measured values ​​of the complex permeability μ' (real part) and the complex permeability μ" (imaginary part) of the noise suppression member in the frequency band of 0.1 GHz to 6 GHz are shown in FIG. Figure 2 .from Figure 2 It is found that the complex magnetic permeability μ' (real part) of Sample 4 is maintained at 1 or higher in the frequency band of 3 GHz to 6 GHz, and is effective for noise suppression up to 6 GHz.

[0044] Next, the surface resistance value of the above-mentioned sample 4 was measured in accordance with JIS K 6911. A commercially available surface resistivity meter (manufactured by Mitsubishi Chemical Corporation, trade name: Hiresta-UP MCP-HT450) was used for the measurement. During the measurement, a probe (electrode) was pressed against the sample surface, and the surface resistance value was measured based on the current flowing through the surface. The surface resistance value of sample 4 was 6×10 6Ω / □.

[0045] [Effect]

[0046] As described above, the noise suppression member can contain magnetic powder in an amount exceeding 50 vol% in the composite composition constituting the noise suppression member. Furthermore, because the binder contains hydrogenated nitrile rubber and polyolefin mixed in the aforementioned composition ratio, even when the composite composition is processed into a sheet, degradation of the sheet's physical properties and processability can be minimized.

[0047] Furthermore, since the content of the flat magnetic powder is adjusted to be within the range of 88.9 mass % to 90 mass %, a noise suppression member exhibiting high magnetic permeability in a high frequency band of 3 GHz to 6 GHz can be formed.

[0048] [Other embodiments]

[0049] While the noise suppression member has been described above using exemplary embodiments, the aforementioned embodiments are merely provided as examples of one aspect of the present disclosure. Specifically, the present disclosure is not limited to the aforementioned exemplary embodiments and can be implemented in various forms without departing from the technical spirit of the present disclosure.

[0050] [Technical Ideas Disclosed in This Specification]

[0051] [Project 1]

[0052] A noise suppression component, wherein:

[0053] A composite composition comprising flat magnetic powder and a binder,

[0054] The flat magnetic powder is any one alloy powder selected from Fe-Si-Cr alloy, Fe-Si alloy and Fe-Cr alloy, or a mixture of two or more alloy powders.

[0055] The median particle size of the flat magnetic powder is 10 μm-30 μm,

[0056] The content of the flat magnetic powder is 88.9% by mass to 90% by mass relative to 100% by mass of the composite composition.

[0057] The adhesive contains hydrogenated nitrile rubber and polyolefin,

[0058] The content of the hydrogenated nitrile rubber is 2% to 9% by mass relative to 100% by mass of the composite composition.

[0059] The content of the polyolefin is 1% by mass to 8% by mass based on 100% by mass of the composite composition.

[0060] [Project 2]

[0061] The noise suppression member according to item 1, wherein

[0062] The content of the flat magnetic powder is 89.2% by mass to 89.5% by mass relative to 100% by mass of the composite composition.

[0063] [Item 3]

[0064] The noise suppression member according to item 1 or item 2, wherein

[0065] The noise suppression member is configured in a sheet shape with a thickness of 0.3 mm to 0.5 mm.

[0066] [Item 4]

[0067] The noise suppression member according to any one of items 1 to 3, wherein

[0068] The noise suppression member has a complex magnetic permeability μ', ie, a real part, of 1 or more in a frequency band of 3 GHz to 6 GHz.

[0069] [Item 5]

[0070] The noise suppression member according to any one of items 1 to 4, wherein

[0071] The surface resistance of the noise suppression member is 1×10 6 Ω / □ or more.

Claims

1. A noise suppression member, wherein: A composite composition comprising flat magnetic powder and a binder, The flat magnetic powder is any one alloy powder selected from Fe-Si-Cr alloy, Fe-Si alloy and Fe-Cr alloy, or a mixture of two or more alloy powders. The median particle size of the flat magnetic powder is 10 μm-30 μm, The content of the flat magnetic powder is 88.9% by mass to 90% by mass relative to 100% by mass of the composite composition. The adhesive contains hydrogenated nitrile rubber and polyolefin, The content of the hydrogenated nitrile rubber is 2% to 9% by mass relative to 100% by mass of the composite composition. The content of the polyolefin is 1% by mass to 8% by mass based on 100% by mass of the composite composition.

2. The noise suppression member according to claim 1, wherein The content of the flat magnetic powder is 89.2% by mass to 89.5% by mass relative to 100% by mass of the composite composition.

3. The noise suppression member according to claim 1 or 2, wherein The noise suppression member is configured in a sheet shape with a thickness of 0.3 mm to 0.5 mm.

4. The noise suppression member according to claim 1 or 2, wherein The noise suppression member has a complex magnetic permeability μ', ie, a real part, of 1 or more in a frequency band of 3 GHz to 6 GHz.

5. The noise suppression member according to claim 1 or 2, wherein The surface resistance of the noise suppression member is 1×10 6 Ω / □ or more.

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