Magnetic Sheet

Abstract

To provide a magnetic sheet suitable for a noise counterplan for a cable.SOLUTION: A magnetic sheet 10 is used as noise counterplan means for a cable. The magnetic sheet 10's width is 5 to 15 mm. The magnetic sheet 10 comprises a magnetic layer 100 and a protective layer 300. The magnetic layer 100 includes soft magnetic material powder 110 and a binder 120. The soft magnetic material powder 110 has a flat shape. The ratio of the soft magnetic material powder 110 in the magnetic layer 100 is 35 to 40% by volume with respect to the whole volume of the magnetic layer 100. The binder 120 is acryl rubber or a mixture of acryl rubber and nitrile rubber. The binder 120 binds the soft magnetic material powder 110. The ratio of the binder 120 in the magnetic layer 100 is 35 to 65% by volume with respect to the whole volume of the magnetic layer 100. The protective layer 300 reinforces the magnetic layer 100.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a magnetic sheet for a cable. [Background technology]

[0002] A widely known method of noise countermeasures for cables is to attach ferrite beads or ferrite cores to the cables. However, since ferrite cores are bulky, when multiple cables with ferrite cores attached are bundled together, the attached ferrite cores take up a large amount of space. In addition, in the above-mentioned case, the part where the ferrite cores are attached becomes larger than the other parts of the cable, which causes a problem of impairing the design of the entire cable.

[0003] In order to avoid the above problems, there is a demand for using a sheet-shaped electromagnetic interference suppressor as disclosed in Patent Document 1 as a countermeasure against noise in cables. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-44069 A Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to provide a magnetic sheet that is suitable for suppressing noise in cables. [Means for solving the problem]

[0006] The present invention provides a first magnetic sheet, A magnetic sheet used as a noise suppression means for a cable, The width of the magnetic sheet is 5 to 15 mm, The magnetic sheet includes a magnetic layer and a protective layer, The magnetic layer includes soft magnetic powder and a binder, The soft magnetic powder has a flat shape, The ratio of the soft magnetic powder in the magnetic layer is 35 to 40% by volume with respect to the total volume of the magnetic layer, the binder is an acrylic rubber or a mixture of an acrylic rubber and a nitrile rubber, The binder binds the soft magnetic powder, The ratio of the binder in the magnetic layer is 35 to 65 volume % with respect to the total volume of the magnetic layer, The protective layer reinforces the magnetic layer. A magnetic sheet is provided.

[0007] The present invention also provides a second magnetic sheet comprising a first magnetic sheet, The magnetic layer further includes a flame retardant, The proportion of the flame retardant in the magnetic layer is 20% by volume or less with respect to the total volume of the magnetic layer. A magnetic sheet is provided.

[0008] The present invention also provides a third magnetic sheet, which is the first or second magnetic sheet, The thickness of the magnetic layer is 20 to 100 μm. A magnetic sheet is provided.

[0009] Furthermore, the present invention provides a fourth magnetic sheet, which is any one of the first to third magnetic sheets, The particle diameter D50 at a cumulative volume percentage of 50 volume% in the volume particle size distribution of the soft magnetic powder is 55 to 90 μm. A magnetic sheet is provided.

[0010] The present invention also provides a fifth magnetic sheet, which is the fourth magnetic sheet, The soft magnetic powder has a particle size D10 of 25 to 55 μm at a cumulative volume percentage of 10 volume% in a volume particle size distribution thereof; The particle diameter D90 at a cumulative volume percentage of 90 volume% in the volume particle size distribution of the soft magnetic powder is 100 to 150 μm. A magnetic sheet is provided.

[0011] Furthermore, the present invention provides a sixth magnetic sheet, which is any one of the first to fifth magnetic sheets, The magnetic sheet further comprises an adhesive layer, The adhesive layer bonds the magnetic layer and the protective layer to each other. A magnetic sheet is provided.

[0012] The present invention also provides a seventh magnetic sheet, which is the sixth magnetic sheet, The adhesive layer is made of a polyether adhesive or a polyester adhesive. A magnetic sheet is provided.

[0013] Furthermore, the present invention provides an eighth magnetic sheet, which is any one of the first to seventh magnetic sheets, The protective layer is made of PET (polyethylene terephthalate), The thickness of the protective layer is 12 μm or more. A magnetic sheet is provided.

[0014] Furthermore, the present invention provides a ninth magnetic sheet, which is any one of the first to eighth magnetic sheets, The magnetic sheet further comprises a metal layer and an additional adhesive layer, The material of the metal layer is Al or Cu, The thickness of the metal layer is 7 μm or more, The additional adhesive layer bonds the metal layer and the protective layer together. A magnetic sheet is provided. Effect of the Invention

[0015] The magnetic sheet of the present invention has the following configuration: the ratio of the soft magnetic powder in the magnetic layer is 35 to 40 volume % relative to the total volume of the magnetic layer; the binder is acrylic rubber or a mixture of acrylic rubber and nitrile rubber; the ratio of the binder in the magnetic layer is 35 to 65 volume % relative to the total volume of the magnetic layer. This allows the magnetic sheet of the present invention to be effective in noise countermeasures for cables without being bulky like ferrite cores. In other words, the magnetic sheet of the present invention is suitable for noise countermeasures for cables. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing a magnetic sheet according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing the magnetic sheet of FIG. 1 wrapped around a cable. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] (Magnetic sheet) 1 and 2, the magnetic sheet 10 according to the embodiment of the present invention is used as a noise countermeasure for the cable 700. The width W of the magnetic sheet 10 satisfies 2.5≦W / D with respect to the diameter D of the cable 700. If W / D<2.5, the ratio of the overlapping portion to the width W of the magnetic sheet 10 becomes large when the magnetic sheet 10 is wound around the cable 700, which is not preferable because it is difficult to wind the magnetic sheet 10 around the cable 700. In addition, in order to ensure the flexibility of the cable 700 when the cable 700 around which the magnetic sheet 10 is wound is bent, it is preferable to satisfy W / D≦7.5. Specifically, the width W of the magnetic sheet 10 is 5 to 15 mm. If the width W of the magnetic sheet 10 is less than 5 mm, the ratio of the overlapping portion to the width W of the magnetic sheet 10 becomes large when the magnetic sheet 10 is wound around the cable 700 with a diameter D of 2 mm, which is not preferable because it is difficult to wind the magnetic sheet 10 around the cable 700. In addition, if the width W of the magnetic sheet 10 is less than 15 mm, the ratio of the overlapping portion to the width W of the magnetic sheet 10 becomes large when the magnetic sheet 10 is wound around the cable 700 with a diameter D of 2 mm, which is not preferable. ExceedsIn this case, the flexibility of cable 700 with magnetic sheet 10 wound therearound and having a diameter D of 2 mm cannot be ensured when the cable 700 is bent, which is not preferable.

[0018] As shown in FIG. 1, a magnetic sheet 10 according to an embodiment of the present invention includes a magnetic layer 100 and a protective layer 300.

[0019] (magnetic layer) 1, the thickness T1 of the magnetic layer 100 in this embodiment is 20 to 100 μm. If the thickness T1 of the magnetic layer 100 exceeds 100 μm, cracks will occur in the overlapping portions of the magnetic sheet 10 in the cable 700 having a diameter D of 2 mm around which the magnetic sheet 10 is wound, which is not preferable.

[0020] As shown in FIG. 1, the magnetic layer 100 includes soft magnetic powder 110 and a binder 120 .

[0021] (Soft magnetic powder) 1, the soft magnetic powder 110 of the present embodiment has a flat shape. Although the shape of the soft magnetic powder 110 is not particularly limited, it is preferable that the soft magnetic powder 110 has a flat shape, and it is preferable that the majority of the flat soft magnetic powder 110 is aligned in the magnetic layer 100 so as to be generally parallel to the main surface of the magnetic layer 100.

[0022] As the material of the soft magnetic powder 110, magnetic stainless steel (Fe-Cr-Al-Si alloy), Fe-Si-Al alloy such as Sendust (registered trademark), Permalloy (Fe-Ni alloy), silicon copper (Fe-Cu-Si alloy), Fe-Si alloy, Fe-Si-B(-Cu-Nb) alloy, Fe-Ni-Cr-Si alloy, Fe-Si-Cr alloy, Fe-Si-Al-Ni-Cr alloy, Mo-Ni-Fe, amorphous alloy, etc. are preferable. In particular, Sendust is more preferable as the material of the soft magnetic powder 110. Such soft magnetic powder 110 may be used alone or in combination. In particular, a metal alloy with high magnetization is desirable for improving the magnetic permeability characteristics.

[0023] In the magnetic sheet 10 of the present embodiment, the ratio of the soft magnetic powder 110 in the magnetic layer 100 is 35 to 40 volume % with respect to the total volume of the magnetic layer 100.

[0024] In the magnetic sheet 10 of this embodiment, the particle diameter D10 of the soft magnetic powder 110 at a cumulative volume percentage of 10 volume% in the volume particle size distribution is 25 to 55 μm. In addition, in the magnetic sheet 10 of this embodiment, the particle diameter D50 of the soft magnetic powder 110 at a cumulative volume percentage of 50 volume% in the volume particle size distribution is 55 to 90 μm. Furthermore, in the magnetic sheet 10 of this embodiment, the particle diameter D90 of the soft magnetic powder 110 at a cumulative volume percentage of 90 volume% in the volume particle size distribution is 100 to 150 μm.

[0025] (Binder) Referring to FIG. 1, the binder 120 of this embodiment is acrylic rubber or a mixture of acrylic rubber and nitrile rubber. The magnetic sheet 10 using polyurethane as the binder 120 is highly elastic and stiff, so it is difficult to wind it around a small-diameter cable 700 with a diameter D of about 2 mm. In addition, when the magnetic sheet 10 using polyurethane as the binder 120 is wound around a cable 700 with a diameter D of about 2 mm, cracks are more likely to occur in the magnetic sheet 10 compared to when the magnetic sheet 10 using acrylic rubber as the binder 120 is wound around a cable 700 with the same diameter. For these reasons, polyurethane is not preferable as the binder 120.

[0026] As shown in Fig. 1, the binder 120 binds the soft magnetic powder 110. Here, the ratio of the binder 120 in the magnetic layer 100 is 35 to 65 volume % with respect to the total volume of the magnetic layer 100. That is, in the magnetic layer 100, the ratio of the soft magnetic powder 110 is 35 to 40 volume % with respect to the total volume of the magnetic layer 100, and the ratio of the binder 120 is 35 to 65 volume % with respect to the total volume of the magnetic layer 100. The ratio of the soft magnetic powder 110 and the binder 120 in the magnetic layer 100 is the ratio at which the density of the soft magnetic powder 110 in the magnetic layer 100 is the highest when acrylic rubber or a mixture of acrylic rubber and nitrile rubber is used as the binder 120. In order to improve the magnetic properties of the magnetic sheet 10, it is preferable to increase the proportion of soft magnetic powder 110 in the magnetic layer 100 as much as possible. However, if the proportion of soft magnetic powder 110 in the magnetic layer 100 exceeds 40 volume %, the soft magnetic powder 110 becomes difficult to bind with the binder 120, so that the particles of the soft magnetic powder 110 tend to fall off from the manufactured magnetic sheet 10, and the proportion of soft magnetic powder 110 in the magnetic layer 100 decreases during use of the magnetic sheet 10, which is not preferable.

[0027] (Flame retardant) 1, the magnetic layer 100 of the present embodiment further contains a flame retardant 130. The flame retardant 130 of the present embodiment is melamine cyanurate. However, the present invention is not limited thereto, and the flame retardant Agent 130 The material may be any material having flame retardancy, but is preferably a nitrogen-based compound having a decomposition temperature of 300° C. or higher. Examples of nitrogen-based compounds suitable for the material of the flame retardant 130 include, for example, tetrazole-based compounds, melamine-based compounds, and mixtures thereof. Examples of particularly preferred materials for the flame retardant 130 include bistetrazole diammonium (C2H8N10) as a tetrazole-based compound, and melamine cyanurate as a melamine-based compound.

[0028] The proportion of the flame retardant 130 in the magnetic layer 100 is 20 volume % or less with respect to the total volume of the magnetic layer 100.

[0029] (protective layer) 1, the protective layer 300 of the present embodiment reinforces the magnetic layer 100. The protective layer 300 of the present embodiment is made of PET (polyethylene terephthalate). However, the present invention is not limited to this, and any flexible sheet-like member may be used, and resins other than PET, such as polyvinyl chloride (PVC), polyurethane (PU), polyimide (PI), etc.

[0030] 1, the thickness T3 of the protective layer 300 is 12 μm or more. If the thickness T3 of the protective layer 300 is less than 12 μm, the protective layer 300 is prone to stretching, which is inconvenient to handle, and is therefore undesirable. In addition, the thickness T3 of the protective layer 300 is preferably 100 μm or less, taking into consideration ease of winding the protective layer 300 around a small-diameter cable 700.

[0031] As shown in FIG. 1, the magnetic sheet 10 of this embodiment further includes an adhesive layer 200. Note that the present invention is not limited thereto, and the magnetic sheet 10 may not include the adhesive layer 200. That is, in the magnetic sheet 10, the magnetic layer 100 and the protective layer 300 may be directly bonded to each other. More specifically, the magnetic sheet 10 may be a magnetic sheet in which the magnetic layer 100 and the protective layer 300 are in close contact with each other, the magnetic sheet 10 being produced by directly applying a slurry produced by mixing the soft magnetic powder 110 and the binder 120 onto the protective layer 300 by any one of a doctor blade method, a spray coating method, a dip coating method, a roll coating method, a spin coating method, a curtain coating method, and a screen printing method. However, in this case, since the magnetic layer 100 is formed directly on the protective layer 300 without the adhesive layer 200, there is a risk that the magnetic layer 100 may peel off from the protective layer 300. Therefore, in order to generate an adhesive force between the magnetic layer 100 and the protective layer 300, the magnetic sheet 10 preferably has an adhesive layer 200.

[0032] (adhesive layer) As shown in FIG. 1, the adhesive layer 200 of this embodiment bonds the magnetic layer 100 and the protective layer 300 together. The adhesive layer 200 is made of a polyether adhesive or a polyester adhesive. In addition, in consideration of the adhesiveness to the magnetic layer 100 using acrylic rubber or a mixture of acrylic rubber and nitrile rubber as the binder 120, a polyether adhesive is particularly preferable for the adhesive layer 200. Note that an acrylic adhesive is not preferable as a material for the adhesive layer 200 because it has poor adhesiveness to the magnetic layer 100 using acrylic rubber or a mixture of acrylic rubber and nitrile rubber as the binder 120.

[0033] Since a magnetic sheet 10 with a thin adhesive layer 200 is easier to wind around a small-diameter cable 700, it is preferable that the thickness of the adhesive layer 200 is as thin as possible. That is, the upper limit of the thickness of the adhesive layer 200 is 5 μm, and it is preferable that it is less than 1 μm, for example. However, in order to ensure that the magnetic layer 100 is well formed on the protective layer 300 and to increase the adhesion between the magnetic layer 100 and the protective layer 300, it is preferable that the adhesive layer 200 has a certain degree of thickness, and for example, the thickness of the adhesive layer 200 is preferably 0.5 μm or more.

[0034] As shown in FIG. 1, the magnetic sheet 10 of this embodiment further comprises a metal layer 500 and an additional adhesive layer 400 .

[0035] (metal layer) 1, the material of the metal layer 500 in this embodiment is Al or Cu. The thickness T5 of the metal layer 500 is 7 μm or more. If the thickness T5 of the metal layer 500 is thinner than 7 μm, sufficient shielding performance cannot be obtained, which is not preferable. In addition, the thickness T5 of the metal layer 500 is preferably 30 μm or less in consideration of ease of winding the metal layer 500 around a small-diameter cable 700.

[0036] (additional adhesive layer) 1, the additional adhesive layer 400 of this embodiment bonds the metal layer 500 and the protective layer 300 to each other. Since a magnetic sheet 10 with a thin additional adhesive layer 400 is easier to wind around a small-diameter cable 700, it is preferable that the thickness of the additional adhesive layer 400 is as thin as possible. That is, the upper limit of the thickness of the additional adhesive layer 400 is 5 μm, and it is preferable that the thickness is less than 1 μm, for example.

[0037] (Method of manufacturing magnetic sheet) An example of a method for manufacturing the magnetic sheet 10 will be described in detail below.

[0038] First, a flat Sendust (registered trademark) powder was prepared as the soft magnetic powder 110, and an acrylic rubber was prepared as the binder 120. Here, in the Sendust (registered trademark) powder, the particle diameter D10 at a cumulative volume percentage of 10 volume% in the volume particle size distribution was 40 μm, the particle diameter D50 at a cumulative volume percentage of 50 volume% in the volume particle size distribution was 75 μm, and the particle diameter D90 at a cumulative volume percentage of 90 volume% in the volume particle size distribution was 130 μm. Next, a viscous slurry was prepared by mixing the Sendust (registered trademark) powder and the acrylic rubber. The above slurry was applied to a carrier film made of PET resin by a doctor blade method and dried, and the coating film after drying was rolled with a roller and then peeled off from the carrier film to obtain a magnetic thin film. Note that the present invention is not limited to this, and the coating film after drying may be peeled off from the carrier film as it is without rolling it with a roller to obtain a magnetic thin film.

[0039] The magnetic thin film thus produced is adhered to a PET film with a polyether adhesive, resulting in the magnetic thin film becoming the magnetic layer 100, the PET film becoming the protective layer 300, and the polyether adhesive becoming the adhesive layer 200.

[0040] The composite thin film made up of the magnetic layer 100, adhesive layer 200 and protective layer 300 is adhered to a metal thin film made of Al with a polyether adhesive. As a result, the metal thin film becomes the metal layer 500, and the polyether adhesive between the composite thin film and the metal layer 500 becomes the additional adhesive layer 400, and the magnetic sheet 10 is manufactured.

[0041] In the produced magnetic sheet 10, the width W was 5 mm, the thickness T1 of the magnetic layer 100 was 50 μm, the thickness T3 of the protective layer 300 was 12 μm, and the thickness T5 of the metal layer 500 was 7 μm. In the produced magnetic sheet 10, the ratio of the soft magnetic powder 110 in the magnetic layer 100 was 38 volume % with respect to the entire volume of the magnetic layer 100, the ratio of the binder 120 in the magnetic layer 100 was 45 volume % with respect to the entire volume of the magnetic layer 100, and the remainder was voids.

[0042] The above-mentioned magnetic sheet 10 was manufactured by adhering a magnetic thin film made by a doctor blade method to a PET film different from the carrier film, but the present invention is not limited to this. For example, the magnetic sheet 10 may be manufactured by adhering a carrier film on which a magnetic thin film is cast to a metal thin film with an adhesive, without going through a process of adhering the magnetic thin film to a PET film with an adhesive. The magnetic sheet 10 manufactured in this way does not have an adhesive layer 200. That is, in the magnetic sheet 10 manufactured in this way, the magnetic layer 100 made of the magnetic thin film and the protective layer 300 made of the carrier film are directly adhered to each other.

[0043] In addition, instead of the above manufacturing method, the magnetic sheet 10 may be manufactured as follows. First, a slurry prepared by mixing the soft magnetic powder 110 and the binder 120 is applied to a PET film without a release agent by a doctor blade method or the like, dried, and the dried coating film is rolled with a roller. As a result, a composite thin film is obtained in which the magnetic layer 100 is formed directly on the PET film that is the protective layer 300. Next, a metal thin film made of copper coated with a polyether adhesive is bonded to the PET film of the obtained composite thin film. As a result, the metal thin film becomes the metal layer 500, and the polyether adhesive interposed between the composite thin film and the metal layer 500 becomes the additional adhesive layer 400, and a magnetic sheet 10 without an adhesive layer 200 is manufactured. In this manufacturing method, the coating film after drying is rolled with a roller, but the coating film after drying may be directly used as a composite thin film without being rolled with a roller.

[0044] Although the present invention has been specifically described above with reference to the embodiment, the present invention is not limited to this and various modifications and changes are possible. [Explanation of symbols]

[0045] 10 Magnetic sheet 100 magnetic layer 110 Soft magnetic powder 120 Binder 130 Flame retardants 200 Adhesive layer 300 protective layer 400 Additional adhesive layer 500 metal layers 700 Cable D diameter T1 Thickness T3 Thickness T5 Thickness W width

Claims

1. A magnetic sheet used as a noise suppression means for a cable, The width of the magnetic sheet is 5 to 15 mm, The magnetic sheet includes a magnetic layer and a protective layer, The magnetic layer includes soft magnetic powder and a binder, The soft magnetic powder has a flat shape, the ratio of the soft magnetic powder in the magnetic layer is 35 to 40 volume % with respect to the total volume of the magnetic layer; the binder is an acrylic rubber or a mixture of an acrylic rubber and a nitrile rubber, The binder binds the soft magnetic powder, the ratio of the binder in the magnetic layer is 35 to 65 volume % with respect to the total volume of the magnetic layer; the protective layer reinforces the magnetic layer, The magnetic sheet further comprises a metal layer and an additional adhesive layer, The material of the metal layer is Al or Cu, The thickness of the metal layer is 7 μm or more, The additional adhesive layer bonds the metal layer and the protective layer together. Magnetic sheet.

2. 2. The magnetic sheet according to claim 1, The magnetic layer further includes a flame retardant, The proportion of the flame retardant in the magnetic layer is 20% by volume or less with respect to the total volume of the magnetic layer. Magnetic sheet.

3. The magnetic sheet according to claim 1 or 2, The thickness of the magnetic layer is 20 to 100 μm. Magnetic sheet.

4. A magnetic sheet according to any one of claims 1 to 3, The particle diameter D of the soft magnetic powder having a cumulative volume percentage of 50 volume% in the volume particle size distribution ５０ is 55 to 90 μm Magnetic sheet.

5. The magnetic sheet according to claim 4, The particle diameter D of the soft magnetic powder is 10% by volume in the cumulative volume percentage in the volume particle size distribution of the soft magnetic powder. １０ is 25 to 55 μm, The particle diameter D of the soft magnetic powder is 90% by volume in the cumulative volume percentage in the volume particle size distribution of the soft magnetic powder. ９０ is 100 to 150 μm Magnetic sheet.

6. A magnetic sheet according to any one of claims 1 to 5, The magnetic sheet further comprises an adhesive layer, The adhesive layer bonds the magnetic layer and the protective layer to each other. Magnetic sheet.

7. 7. The magnetic sheet according to claim 6, The adhesive layer is made of a polyether adhesive or a polyester adhesive. Magnetic sheet.

8. A magnetic sheet according to any one of claims 1 to 7, The protective layer is made of PET (polyethylene terephthalate), The thickness of the protective layer is 12 μm or more. Magnetic sheet.

Images