Electromagnetic wave shielding film

Abstract

Provided is an electromagnetic wave shield film from which static electricity that has accumulated during manufacture or transfer can be readily dissipated. An electromagnetic wave shield film of the present invention is characterized by comprising a protection layer disposed in an outermost layer, and a shield layer laminated on the inside of the protection layer, the protection layer having a surface resistivity of 1.0×105 to 2.0×1012 Ω / □, and the protection layer includes a binder resin and carbon particles having an average particle diameter of 0.1-15 μm.

Description

[Technical field]

[0001] The present invention relates to an electromagnetic wave shielding film. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an electromagnetic wave shielding film has been attached to a printed wiring board such as a flexible printed wiring board (FPC) to shield against external electromagnetic waves.

[0003] An electromagnetic wave shielding film usually has a structure in which a conductive adhesive layer, a shielding layer made of a metal thin film or the like, and an insulating layer are laminated in this order. The electromagnetic wave shielding film is superimposed on a printed wiring board and then hot-pressed, whereby the electromagnetic wave shielding film is adhered to the printed wiring board by the adhesive layer to produce a shielded printed wiring board. After this adhesion, components are mounted on the printed wiring board by solder reflow. The printed wiring board is also configured such that the print pattern on the base film is covered with an insulating film.

[0004] As such an electromagnetic wave shielding film, Patent Document 1 discloses an electromagnetic wave shielding film comprising an insulating resin layer, a shielding layer adjacent to the insulating resin layer, and a conductive adhesive layer provided on the shielding layer opposite the insulating resin layer, wherein the shielding layer comprises a plurality of metal layers having a thickness of 1 μm or less, and a non-metallic layer interposed between the plurality of metal layers. Furthermore, Patent Document 2 discloses an electromagnetic wave shielding sheet including a conductive layer and an insulating layer, the insulating layer containing a thermosetting resin, a curing agent, and a black colorant, and the black colorant having an average primary particle size of 20 to 100 nm. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-136437 A [Patent Document 2] JP 2016-143751 A Summary of the Invention [Problem to be solved by the invention]

[0006] When manufacturing the electromagnetic shielding film described in Patent Document 1, the electromagnetic shielding film is transported by roll transport, and static electricity is generated in the insulating layer when the insulating layer comes into contact with the roll. When static electricity is generated in the insulating layer, electricity does not easily flow even if the insulating layer is connected to an earth, and static electricity accumulates. The electromagnetic wave shielding film is then cut or laminated and stored. If static electricity accumulates in the insulating layer, problems may occur, such as the film not being able to be cut properly, or when trying to take the films out individually after storage, they may stick to other electromagnetic shielding films and become difficult to peel off (i.e., a blocking problem).

[0007] In the electromagnetic shielding sheet described in Patent Document 2, although the insulating layer contains a conductive black colorant, when static electricity occurs in the insulating layer, even if the insulating layer is connected to earth, electricity does not flow easily, and the static electricity accumulates. Therefore, the electromagnetic shielding sheet described in Patent Document 2 also has a blocking problem. In addition, since the average particle size of the black colorant is small at 20 to 100 nm, the unevenness of the surface of the insulating layer is reduced, causing the insulating layer to become glossy, and there is a problem that scratches or the like that occur on the surface of the insulating layer are noticeable.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide an electromagnetic wave shielding film that easily dissipates static electricity that accumulates during production or transportation. [Means for solving the problem]

[0009] The electromagnetic wave shielding film of the present invention includes a protective layer disposed as an outermost layer and a shielding layer laminated on the inner side of the protective layer, and the surface resistivity of the protective layer is 1.0×10 5 ~2.0×10 12 The protective layer is characterized in that it contains a binder resin and carbon particles having an average particle size of 0.1 to 15 μm.

[0010] In the electromagnetic wave shielding film of the present invention, the surface resistivity of the protective layer arranged on the outermost layer is 1.0×10 5 ~2.0×10 12 It is Ω / □. When the surface resistivity of the protective layer is within the above range, the protective layer has static electricity diffusion properties, so that even if static electricity accumulates on the protective layer, the static electricity accumulated on the protective layer can be quickly dissipated by connecting it to an earth. As a result, static electricity is less likely to accumulate in the electromagnetic wave shielding film as a whole. The surface resistivity above is 1.0×10 5 If it is less than Ω / □, static electricity can be dissipated instantly, but it is likely to be accompanied by sparks when the static electricity is dissipated. The surface resistivity above is 2.0×10 12 If the resistance exceeds Ω / □, it becomes difficult for current to flow even if the protective layer is connected to earth. Therefore, it becomes difficult for static electricity to dissipate.

[0011] In the electromagnetic wave shielding film of the present invention, the protective layer contains a binder resin and carbon particles having an average particle size of 0.1 to 15 μm. When the protective layer contains carbon particles having an average particle size in the above range, the carbon particles are appropriately exposed on the surface of the protective layer, and the surface resistivity of the protective layer is increased to 1.0×10 5 ~2.0×10 12 In addition, since the surface of the protective layer is uneven, the protective layer can have a low gloss. Therefore, even if the protective layer is scratched, the scratch is not noticeable. If the average particle size of the carbon particles is less than 0.1 μm, the carbon particles will be embedded in the protective layer and will not be easily exposed on the surface of the protective layer, making it difficult for current to flow and for static electricity to dissipate even if the protective layer is connected to earth. If the average particle size of the carbon particles exceeds 15 μm, the surface irregularities of the protective layer become too large.

[0012] In the electromagnetic wave shielding film of the present invention, the content of the carbon particles in the protective layer is preferably 5 to 30% by weight. When the content of the carbon particles is within the above range, the surface resistivity of the protective layer is increased to 1.0×10 5 ~2.0×10 12 In addition, the protective layer can be suitably colored black, improving the hiding power.

[0013] The electromagnetic wave shielding film of the present invention may be formed by laminating, in order, the protective layer, an insulating layer, a metal layer functioning as the shielding layer, and a conductive adhesive layer. The electromagnetic wave shielding film of the present invention may be formed by laminating, in order, the protective layer, the insulating layer, and the conductive adhesive layer functioning as the shielding layer. The electromagnetic wave shielding film having such a configuration has sufficient electromagnetic wave shielding performance. In addition, since a protective layer is formed on the outermost layer, accumulated static electricity can be quickly dissipated. Effect of the Invention

[0014] According to the electromagnetic wave shielding film of the present invention, it is possible to provide an electromagnetic wave shielding film which easily dissipates static electricity that has accumulated during production or transportation. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a first embodiment of the present invention. [Diagram 2]FIG. 2 is a process diagram that illustrates an example of roll transport of the electromagnetic wave shielding film according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The electromagnetic wave shielding film of the present invention will be specifically described below. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope of the present invention.

[0017] (First embodiment) First, an electromagnetic wave shielding film according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a first embodiment of the present invention.

[0018] The electromagnetic wave shielding film 10 shown in FIG. 1 is formed by laminating a protective layer 20, an insulating layer 30, a metal layer 40, and a conductive adhesive layer 50 in this order. The metal layer 40 functions as a shielding layer in the electromagnetic wave shielding film 10. In the electromagnetic wave shielding film 10, the protective layer 20 is disposed as the outermost layer, and the metal layer 40 is disposed inside thereof.

[0019] In the electromagnetic wave shielding film 10, the surface resistivity of the protective layer 20 is 1.0×10 5 ~2.0×10 12 The surface resistivity of the protective layer 20 is 1.0×10 6 ~1.0×10 11 Ω / □ is preferable, and 1.0×10 7 ~1.0×10 9 It is more preferable that it is Ω / □. When the surface resistivity of protective layer 20 is within the above range, protective layer 20 has static electricity diffusion properties, so that even if static electricity accumulates on protective layer 20, the static electricity accumulated on protective layer 20 can be dissipated by connecting it to earth. As a result, the electromagnetic wave shielding film 10 as a whole is less susceptible to static electricity accumulation. The surface resistivity above is 1.0×10 5 If it is less than Ω / □, static electricity can be dissipated instantly, but it is likely to be accompanied by sparks when the static electricity is dissipated. The surface resistivity above is 2.0×10 12 If the resistance exceeds Ω / □, it becomes difficult for current to flow even if the protective layer is connected to earth. Therefore, it becomes difficult for static electricity to dissipate.

[0020] In the electromagnetic wave shielding film 10, the protective layer 20 contains a binder resin and carbon particles having an average particle size of 0.1 to 15 μm. The average particle size of the carbon particles is preferably 1 to 10 μm. When the protective layer 20 contains carbon particles having an average particle size in the above range, the carbon particles are appropriately exposed on the surface of the protective layer 20, and the surface resistivity of the protective layer 20 is increased to 1.0×10 5 ~2.0×10 12 In addition, since unevenness is formed on the surface of the protective layer 20, a low gloss level can be achieved for the protective layer 20. Therefore, even if scratches or the like occur on the protective layer 20, the scratches or the like are less noticeable. If the average particle size of the carbon particles is less than 0.1 μm, the carbon particles will be embedded in the protective layer and will not be easily exposed on the surface of the protective layer, making it difficult for current to flow and for static electricity to dissipate even if the protective layer is connected to earth. If the average particle size of the carbon particles exceeds 15 μm, the surface irregularities of the protective layer become too large. The carbon particles may form secondary particles, the size of which is preferably 1 to 15 μm.

[0021] In this specification, the average particle diameter of the carbon particles means the average value of the long axis measurements of the surface of the protective layer 20 (length × width = 250 μm × 350 μm) taken at a magnification of 1000 times using a digital microscope (VHX-5000, manufactured by Keyence Corporation), randomly selecting five primary carbon particles from the image taken.

[0022] In the electromagnetic wave shielding film 10, the content of carbon particles in the protective layer 20 is preferably 5 to 30% by weight, and more preferably 10 to 30% by weight. When the content of carbon particles is within the above range, the surface resistivity of the protective layer 20 is increased to 1.0×10 5 ~2.0×10 12 It can be expressed as Ω / □. If the content of the carbon material in the protective layer is less than 5% by weight, it is difficult to obtain a surface resistivity of the protective layer within a favorable range. If the content of the carbon material in the protective layer exceeds 30% by weight, the surface of the protective layer becomes uneven, and the scratch resistance of the protective layer tends to decrease.

[0023] The type of carbon particles is not particularly limited as long as it can adjust the surface resistivity of the protective layer 20, and may be, for example, amorphous carbon or graphite.

[0024] In the electromagnetic wave shielding film 10, the protective layer 20 may contain a carbon material other than carbon particles. The surface resistivity of the protective layer 20 can be adjusted by the carbon material. The shape of the carbon material other than the carbon particles is not particularly limited, but for example, carbon fibers, carbon nanotubes, etc. can be used.

[0025] The binder resin contained in the protective layer 20 is preferably composed of a thermoplastic resin, a thermosetting resin, an active energy ray curable resin, or the like.

[0026] The thermoplastic resin is not particularly limited, but examples thereof include styrene-based resins, vinyl acetate-based resins, polyester-based resins, polyethylene-based resins, polypropylene-based resins, imide-based resins, and acrylic-based resins.

[0027] The thermosetting resin is not particularly limited, but examples thereof include phenol-based resins, epoxy-based resins, urethane-based resins, melamine-based resins, and alkyd-based resins.

[0028] The active energy ray-curable resin is not particularly limited, but examples thereof include polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule.

[0029] The binder resin contained in the protective layer 20 may be a single material or may be two or more materials.

[0030] The protective layer 20 may contain, as necessary, a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity adjuster, an antiblocking agent, and the like.

[0031] The thickness of the protective layer 20 is not particularly limited and can be appropriately set as necessary, but is preferably 0.1 to 15 μm, and more preferably 1 to 10 μm.

[0032] The protective layer 20 is preferably black in color. When the protective layer 20 is black in color, the concealing properties are improved, and the design is improved. The protective layer 20 is L * a * b * In the color system, L * The value is preferably 10 to 30, * The value is preferably 0.1 to 10, and b * The value is preferably from -5 to 5.

[0033] The scratch hardness of the protective layer 20 in accordance with JIS K 5600-5-4 is preferably H or more, and more preferably 2H or more. When the scratch hardness of the protective layer 20 is H or more, the scratch resistance is improved and the protective layer 20 is less likely to peel off, so that a good appearance can be maintained.

[0034] The surface roughness Ra of the protective layer 20 is preferably 5.0 μm or less, and more preferably 3.0 to 0.1 μm. When the surface roughness Ra of the protective layer 20 is 5.0 μm or less, the protective layer has good scratch resistance.

[0035] The 85° gloss of the protective layer 20 as measured by a BYK-Gardner microterry gloss is preferably 30-80, and more preferably 40-60. When the 85° gloss of the protective layer 20 is within the above range, the surface roughness Ra of the protective layer 20 is small, and the scratch resistance of the protective layer is improved.

[0036] In the electromagnetic wave shielding film 10, the material of the insulating layer 30 is not particularly limited, and is preferably composed of a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable resin composition, or the like.

[0037] Examples of the thermoplastic resin composition include, but are not limited to, a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, an imide-based resin composition, and an acrylic-based resin composition.

[0038] The thermosetting resin composition is not particularly limited, but examples thereof include a phenol-based resin composition, an epoxy-based resin composition, a urethane-based resin composition, a melamine-based resin composition, an alkyd-based resin composition, an imide-based resin composition, and an amide-based resin composition.

[0039] The active energy ray-curable resin composition is not particularly limited, but examples thereof include polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule.

[0040] The insulating layer 30 may be made of one type of material alone, or may be made of two or more types.

[0041] The insulating layer 30 may contain, as necessary, a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity adjuster, an antiblocking agent, and the like.

[0042] The thickness of the insulating layer 30 is not particularly limited and can be appropriately set as necessary, but is preferably 0.1 to 15 μm, and more preferably 1 to 10 μm.

[0043] In this specification, the term "insulating layer" refers to a layer having a surface resistivity of 2.0×10 12 This means a resin layer exceeding Ω / □.

[0044] In the electromagnetic wave shielding film 10, the metal layer 40 may be a metal foil, a metal plating layer, a metal deposition layer, or the like. The material of the metal layer 40 is preferably, for example, gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, zinc, or an alloy thereof, etc. When the metal layer 40 is made of these metals, the shielding property of the metal layer 40 is improved. Among these, a copper layer and a silver layer are preferred from the viewpoint of excellent shielding performance against electromagnetic waves in the high frequency band, and a copper layer is preferred from the viewpoint of economy.

[0045] The thickness of the metal layer 40 is preferably 0.1 to 10 μm, and more preferably 1 to 6 μm. If the thickness of the metal layer 40 is less than 0.1 μm, the shielding properties are likely to decrease. Furthermore, since there is almost no improvement in the shielding properties even if the thickness of metal layer 40 exceeds 10 μm, by making the thickness 10 μm or less, it is possible to maximize the shielding properties while reducing costs, and it is also possible to design electronic devices equipped with the electromagnetic wave shielding film of the present invention to be smaller.

[0046] In the electromagnetic wave shielding film 10, the conductive adhesive layer 50 may have isotropic conductivity or anisotropic conductivity. As described above, the conductive adhesive layer 50 is disposed on the printed wiring board. In such a case, when the conductive adhesive layer 50 having either isotropic conductivity or anisotropic conductivity is brought into contact with the ground wiring of the printed wiring board, the ground wiring of the printed wiring board and the metal layer 40 of the electromagnetic wave shielding film 10 can be electrically connected via the conductive adhesive layer 50. This allows the electromagnetic wave shielding film 10 to suitably shield electromagnetic waves.

[0047] When the conductive adhesive layer 50 has anisotropic conductivity, the transmission characteristics of high frequency signals transmitted through the signal circuits of the printed wiring board are improved compared to when the conductive adhesive layer 50 has isotropic conductivity.

[0048] The conductive adhesive layer 50 includes a conductive filler and an adhesive resin.

[0049] The conductive filler of the conductive adhesive layer 50 is not particularly limited, but may be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating copper powder, fine particles of polymer particles or glass beads coated with metal, etc. Among these, from the viewpoint of economy, copper powder or silver-coated copper powder, which is inexpensively available, is preferable.

[0050] The shape of the conductive filler is not particularly limited, and can be appropriately selected from spherical, flake, scale, dendrite, rod, fiber, etc. Among these, the flake shape is preferable. When the conductive filler is a flake-shaped conductive filler, the conductive filler also bends when the electromagnetic shielding film 10 is bent, and contact between the conductive filler particles is easily maintained, so that the conductivity of the conductive adhesive layer is less likely to decrease.

[0051] The average major axis of the conductive filler is not particularly limited, but is preferably 0.5 to 15.0 μm, and more preferably 5 to 13.0 μm. When the average major axis of the conductive filler is 0.5 μm or more, the conductive adhesive layer has good electrical conductivity. When the average major axis of the conductive filler is 15.0 μm or less, the conductive adhesive layer can be made thin. In this specification, the average major axis of the conductive filler refers to a value measured by the following method. A scanning electron microscopy (SEM) image of the cross section of the conductive adhesive layer is obtained. The average long diameter of the conductive filler means the average value of the long diameters of any five conductive fillers in the SEM image.

[0052] The weight percentage of the conductive filler contained in the conductive adhesive layer 50 is preferably 10 to 80% by weight. When the conductive adhesive layer 50 has anisotropic conductivity, the weight percentage of the conductive filler contained in the conductive adhesive layer 50 is preferably 10 to 40% by weight, and more preferably 15 to 35% by weight.

[0053] The thickness of the conductive adhesive layer 50 is not particularly limited and can be appropriately set as necessary, but is preferably 0.5 to 30.0 μm. If the thickness of the conductive adhesive layer is less than 0.5 μm, it becomes difficult to obtain good electrical conductivity. If the thickness of the conductive adhesive layer exceeds 30.0 μm, the entire electromagnetic shielding film becomes thick and difficult to handle.

[0054] The material of the adhesive resin contained in the conductive adhesive layer 50 is not particularly limited, but examples of the material that can be used include thermoplastic resins such as styrene-based resins, vinyl acetate-based resins, polyester-based resins, polyethylene-based resins, polypropylene-based resins, imide-based resins, amide-based resins, and acrylic-based resins, and thermosetting resins such as phenol-based resins, epoxy-based resins, urethane-based resins, melamine-based resins, and alkyd-based resins. The adhesive resin material of the conductive adhesive layer 50 may be one of these alone or a combination of two or more of them.

[0055] Next, the principle by which static electricity in the electromagnetic wave shielding film of the present invention quickly dissipates will be described with reference to the drawings. FIG. 2 is a process diagram that illustrates an example of roll transport of the electromagnetic wave shielding film according to the first embodiment of the present invention.

[0056] As shown in FIG. 2, when the electromagnetic shielding film 10 is transported by a roll device 60, if the roll device 60 and the electromagnetic shielding film 10 come into contact with each other, static electricity is generated in the electromagnetic shielding film 10 due to friction. As shown in FIG. 2, by connecting the roll device 60 to the ground, a current flows from the protective layer arranged on the outermost layer of the electromagnetic shielding film 10 to the ground, and static electricity can be quickly dissipated.

[0057] If the electromagnetic shielding film does not have a protective layer and has an insulating layer as the outermost layer, the insulating layer does not allow current to flow easily, and even if the roll device is connected to earth, static electricity accumulated in the insulating layer does not easily flow to earth. Therefore, static electricity tends to remain accumulated.

[0058] In FIG. 2, the roll device 60 is connected to the ground, but the position where it is connected to the ground is not particularly limited as long as static electricity can be dissipated from the electromagnetic wave shielding film of the present invention.

[0059] Second embodiment Next, an electromagnetic wave shielding film according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a second embodiment of the present invention.

[0060] The electromagnetic wave shielding film 110 shown in FIG. 3 is formed by laminating a protective layer 120, an insulating layer 130, and a conductive adhesive layer 150 in this order. The conductive adhesive layer 150 functions as a shielding layer in the electromagnetic wave shielding film 110. In the electromagnetic wave shielding film 110, the protective layer 120 is disposed as the outermost layer, and the conductive adhesive layer 150 is disposed inside thereof.

[0061] In the electromagnetic wave shielding film 110, the preferred structures of the protective layer 120 and the insulating layer 130 are the same as the preferred structures of the protective layer 20 and the insulating layer 30 in the electromagnetic wave shielding film 10 described above.

[0062] In the electromagnetic wave shielding film 110, the conductive adhesive layer 150 has isotropic conductivity and functions as a shielding layer. Apart from this configuration and function, the conductive adhesive layer 150 preferably has the same configuration as the conductive adhesive layer 50 of the electromagnetic wave shielding film 10.

[0063] Like the electromagnetic wave shielding film 10, the electromagnetic wave shielding film 110 is capable of quickly dissipating accumulated static electricity.

[0064] (Other embodiments) In the electromagnetic wave shielding films according to the first and second embodiments, an insulating layer is formed between the protective layer and the shielding layer (metal layer or conductive adhesive layer). However, in the electromagnetic wave shielding film of the present invention, the protective layer and the shielding layer may be in direct contact with each other. EXAMPLES

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0066] Example 1 First, a support film made of polyethylene terephthalate that had been subjected to a release treatment was prepared.

[0067] Next, 80 parts by weight of polyester melamine as a binder resin and 20 parts by weight of graphite particles (average particle size: 5 μm) as a carbon material were mixed together to prepare a composition for a protective layer. The average particle size of the graphite particles is shown as a result of measurement based on the above-mentioned method for measuring the average particle size of carbon particles after preparing the protective layer composition. Thereafter, the composition for protective layer was applied to a support film to a thickness of 5 μm to form a protective layer.

[0068] Next, an adhesive resin made of epoxy resin was applied onto the protective layer to a thickness of 5 μm to form an insulating layer.

[0069] Next, a copper foil with a thickness of 1 μm was placed on the insulating layer to form a metal layer.

[0070] Next, 35% by weight of epoxy resin, which is an adhesive resin, and 65% by weight of copper powder, which is a conductive filler, were mixed together to prepare a conductive adhesive. Thereafter, the conductive adhesive was coated on the metal layer to a thickness of 5 μm, and a conductive adhesive layer was formed by using a lip coating method.

[0071] Through the above steps, the electromagnetic wave shielding film according to Example 1 was produced.

[0072] (Example 2) to (Example 5) The electromagnetic wave shielding films according to Examples 2 to 5 were produced in the same manner as in Example 1, except that the content of the graphite particles contained in the protective layer was set as shown in Table 1.

[0073] Comparative Example 1 An electromagnetic wave shielding film according to Comparative Example 1 was produced in the same manner as in Example 1, except that no protective layer was formed.

[0074] [Table 1]

[0075] (Surface resistivity measurement) The surface resistivity of the protective layer of the electromagnetic shielding film according to each Example and the insulating layer of the electromagnetic shielding film according to Comparative Example 1 was measured using an ADCMT 8340A Ultra High Resistance Meter. The results are shown in Table 1.

[0076] (Steel wool adhesion test) The electromagnetic wave shielding film according to each of the Examples and Comparative Examples was cut into a size of 250 mm length×250 mm width to prepare a test piece. Steel wool powder was placed on the protective layer of the test piece (insulating layer in the test piece of Comparative Example 1) to the extent that the protective layer was no longer visible, and then the test piece was turned upside down to remove the steel wool powder. After the steel wool powder was removed, the protective layer of the test piece was visually inspected to see if any steel wool powder had adhered thereto due to static electricity. The results are shown in Table 1. The evaluation criteria are as follows: ◯: The area of ​​adhesion of steel wool powder was less than 30% of the entire surface of the protective layer (insulating layer). Δ: The area of ​​the steel wool powder adhered to was 30% or more and less than 50% of the entire surface of the protective layer (insulating layer). ×: The area of ​​the steel wool powder adhered to was 50% or more of the entire surface of the protective layer (insulating layer).

[0077] (Scratch hardness measurement) The scratch hardness of the protective layer of the electromagnetic shielding film according to each Example and the insulating layer of the electromagnetic shielding film according to Comparative Example 1 was measured in accordance with JIS K 5600-5-4 under conditions of load: 750±10 g, pencil angle: 45°, scratch speed: 0.5 to 1.0 mm / s, and pencil used: Uni manufactured by Mitsubishi Pencil Co., Ltd. The results are shown in Table 1.

[0078] (surface roughness measurement) The surface roughness Ra of the protective layer of the electromagnetic shielding film according to each Example and the insulating layer of the electromagnetic shielding film according to Comparative Example 1 was measured using a PTELICS H1200 manufactured by Lasertec Corp. The results are shown in Table 1.

[0079] (85° gloss measurement) The 85° gloss of the protective layer of the electromagnetic shielding film according to each Example and the insulating layer of the electromagnetic shielding film according to Comparative Example 1 was measured using a BYK-Gardner Micro Tally Gloss. The results are shown in Table 1.

[0080] (Opacity test) The concealing properties of the electromagnetic wave shielding films according to the respective Examples and Comparative Examples were evaluated visually. The evaluation criteria were as follows. The results are shown in Table 1. ◯: No metal layer was observed when visually observed from the protective layer side (insulating layer side in Comparative Example 1). Δ: When visually observed from the protective layer side (insulating layer side in Comparative Example 1), a slight metal layer was observed. ×: A metal layer was confirmed when visually observed from the protective layer side (insulating layer side in Comparative Example 1).

[0081] As shown in Table 1, in the electromagnetic wave shielding film according to each example, the surface resistivity of the protective layer is 1.0×10 5 ~2.0×10 12 It was confirmed that the resistance to static electricity was Ω / □. In addition, the results of the steel wool powder adhesion test revealed that the electromagnetic wave shielding films according to the respective examples easily dissipate static electricity. [Explanation of symbols]

[0082] 10, 110 Electromagnetic wave shielding film 20, 120 protective layer 30, 130 Insulation layer 40 metal layer 50, 150 Conductive adhesive layer 60 Roller device

Claims

1. A protective layer disposed on the outermost layer; a shielding layer laminated on the inner side of the protective layer, The surface resistivity of the protective layer is 1.0×10 ５ ~2.2 x 10 １０ Ω / □, the protective layer contains a binder resin and carbon particles having an average particle size of 0.1 to 15 μm; An electromagnetic wave shielding film, characterized in that a black adhesive layer composed of a black pigment and an adhesive component is not formed on the surface of the shielding layer on the protective layer side.

2. 2. The electromagnetic wave shielding film according to claim 1, wherein the content of the carbon particles in the protective layer is 5 to 30% by weight.

3. 3. The electromagnetic shielding film according to claim 1, wherein the electromagnetic shielding film is formed by laminating in order the protective layer, an insulating layer, a metal layer functioning as the shielding layer, and a conductive adhesive layer.

4. 3. The electromagnetic shielding film according to claim 1, wherein the electromagnetic shielding film is formed by laminating the protective layer, an insulating layer, and a conductive adhesive layer functioning as the shielding layer in this order.

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