JP2007149761A - Electromagnetic shielding sheet, and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permeable electromagnetic shielding sheet which can be bent for use, and is excellent in electromagnetic shielding properties, and to provide a method of manufacturing the same. <P>SOLUTION: The electromagnetic shielding sheet consists of a metallic foil and nonwoven fabric. The nonwoven fabric is stuck to at least one of surfaces of the metallic foil via an adhesive, and through-holes are scattered on the foil. The electromagnetic shielding sheet can be manufactured by a step of sticking the nonwoven cloth to one of the surfaces of the metallic foil via the adhesive; and a step in which a low hardness pressing material and the metallic foil come into contact, a high hardness pressing material and the nonwoven fabric are pressed in contact, and the metallic foil is stretched to have the through holes scattered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave shielding sheet and a manufacturing method thereof.

  In recent years, electrical products and electronic devices have become widespread in various places, and along with this, problems such as electromagnetic waves generated from these devices have caused malfunctions and noise in other electrical products and electronic devices. Yes. For this reason, various electromagnetic shielding materials have been proposed so as not to leak electromagnetic waves from these devices and prevent electromagnetic waves from entering these devices.

  For example, in Japanese Patent Laid-Open No. 59-201856, “shape retention is characterized in that a cloth is laminated on at least one surface of a metal foil and the metal foil and the cloth are bonded with an adhesive disposed discontinuously. A sheet-like substance having properties ”is disclosed (Patent Document 1). Japanese Patent Publication No. 4-41882 discloses that “a non-magnetic metal foil provided with a large number of air holes dispersed over the entire surface is dispersed between mats on which small pieces of vegetable fiber formed by applying an adhesive are spread. In addition, a thermocompression-bonded particle board for shielding electromagnetic waves ”is disclosed (Patent Document 2). Furthermore, the entire specification of Japanese Utility Model Publication No. 59-46236 states that “an FRP in which a large number of small holes are formed by stitch needles from both sides of a laminate in which an aluminum foil is sandwiched between mats made of glass fiber bundles. "Reinforcing Material" is disclosed (Patent Document 3).

JP 59-201856 A (Claim 1, Examples, etc.) Japanese Patent Publication No. 4-41882 (Claim 1 etc.) Japanese Utility Model Publication No. 59-46236 (text of utility model registration request, specification, page 5, line 2 to line 14)

  Since the sheet-like substance disclosed in Patent Document 1 described above has a metal foil and a fabric, the sheet-like substance has excellent electromagnetic wave shielding properties. However, the sheet-like substance produced under the conditions described in the Examples of Patent Document 1 Was not breathable. Therefore, when this sheet-like substance is used, for example, as a wall material for a building, condensation is likely to occur, and soot and the like are likely to propagate.

  Further, the particle board disclosed in the above-mentioned Patent Document 2 is literally a board and therefore has no flexibility. Further, since the reinforcing material for FRP disclosed in Patent Document 3 described above has the glass fiber mats joined together by stitch needles, the glass fiber mat and the aluminum foil are easily peeled off when bent. Thus, since it was difficult to bend and use the particle board or the FRP reinforcing material disclosed in Patent Document 2 or 3, the intended use was limited. For example, in order to be used for a housing of an electronic device, it is necessary to deform along the shape of the housing, but it has been difficult to apply to such a use.

  The present invention has been made in order to solve the above-mentioned problems, and provides an electromagnetic wave shielding sheet excellent in electromagnetic wave shielding properties, which is air permeable and can be used by bending, and a method for producing the same. Objective.

  The invention according to claim 1 of the present invention is “an electromagnetic wave shielding sheet comprising a metal foil and a nonwoven fabric, wherein the nonwoven fabric is bonded to at least one surface of the metal foil with an adhesive, and the metal foil has a through-hole. Is an electromagnetic wave shielding sheet characterized by being scattered. "

  The invention according to claim 2 of the present invention is "the electromagnetic wave shielding sheet according to claim 1, wherein the metal foil is in a wrinkled state."

  The invention according to claim 3 of the present invention is “the electromagnetic wave shielding sheet according to claim 1 or 2, wherein the metal foil has a thickness of 20 μm or less”.

  The invention according to claim 4 of the present invention is "the electromagnetic wave shielding sheet according to any one of claims 1 to 3, wherein the average fineness of the nonwoven fabric constituting fibers is 1.5 dtex or more". is there.

  The invention according to claim 5 of the present invention is that "a step of bonding a non-woven fabric to one side of a metal foil with an adhesive, a low-hardness pressing material having a hardness (type A durometer hardness test) of 50 or less, and a metal foil. A high hardness pressing material having a hardness (type A durometer hardness test) of 90 or more and a non-woven fabric in contact with each other, pressing the metal foil, and extending the metal foil to disperse the through holes. "The manufacturing method of the electromagnetic wave shielding sheet."

  According to the first aspect of the present invention, since the metal foil is provided, the electromagnetic shielding property is excellent, and the metal foil is excellent in air permeability because the through holes are scattered. Furthermore, the metal foil is reinforced with a non-woven fabric, and since the non-woven fabric and the metal foil are bonded with an adhesive, the metal foil and the non-woven fabric are not peeled even when bent, or the metal foil is not damaged and bent. Is an electromagnetic shielding sheet that can also be used.

  According to the second aspect of the present invention, the metal foil is in a state of wrinkles, and even if the metal foil is bent, the wrinkles only extend, so that the metal foil is not easily cracked. In addition, no abnormal noise is generated when bent. Furthermore, it has excellent design properties.

  According to claim 3 of the present invention, since the thickness of the metal foil is 20 μm or less, the metal foil and the nonwoven fabric can be in close contact with each other, and even when bent, the metal foil and the nonwoven fabric are difficult to peel off. It is.

  According to claim 4 of the present invention, since the average fineness of the nonwoven fabric constituting fibers is as thick as 1.5 dtex or more, the metal foil and the nonwoven fabric can be in close contact with each other, and the metal foil and the nonwoven fabric are peeled even when bent. It is hard to do.

  According to claim 5 of the present invention, the electromagnetic wave shielding sheet according to claim 1 or claim 2 can be easily manufactured.

  The electromagnetic wave shielding sheet of the present invention includes a metal foil so that electromagnetic waves can be shielded. The metal constituting the metal foil is not particularly limited as long as it can shield electromagnetic waves. For example, aluminum, iron, silver, copper, nickel, stainless steel, lead, zinc, tin, or any of these metals Mention may be made of alloys. Among these, aluminum is particularly preferable because it is versatile, inexpensive, and practical.

  The thickness of the metal foil is not particularly limited, but it is preferably 20 μm or less and is preferably 15 μm or less so that the metal foil and the nonwoven fabric can be easily adhered to each other as described later and hardly peeled even when bent. Is more preferable, and it is still more preferable that it is 12 micrometers or less. In addition, when the thickness of the metal foil is less than 5 μm, the metal foil is easily damaged when bent, so that the thickness is preferably 5 μm or more, and more preferably 6 μm or more. The thickness of the metal foil in the present invention refers to a value measured by JIS-B-7502 outside micrometer 0-25 mm electronic digital display.

  Since the metal foil in the electromagnetic wave shielding sheet of the present invention has through holes dispersed therein and has air permeability, it can be used for applications that require air permeability. For example, no condensation occurs even when used as a wall material for a building. Since this through hole imparts air permeability, its shape is not particularly limited. However, if the size of one through-hole exceeds 10 mm, the electromagnetic wave shielding property is lowered, so that it is preferably 10 mm or less, more preferably 5 mm or less, still more preferably 3 mm or less. More preferably, it is as follows. On the other hand, the size of one through-hole is preferably 10 μm or more so as not to impair the air permeability. Moreover, since such through-holes should just have air permeability, they may be scattered regularly or irregularly. The size of one through hole means the diameter when the shape of the through hole is circular, and the longest length of the through holes when the shape of the through hole is non-circular. It means one half of the sum of the length (major axis) that can be taken and the length (minor axis) that can take the shortest length among the through holes.

Moreover, the air volume measured using the Frazier type tester based on JIS L1096A is 1-500 cm < ³ > / cm so that the air permeability of metal foil is excellent in air permeability and electromagnetic shielding properties. ² · s is preferable, and 1 to 300 cm ³ / cm ² · s is more preferable.

  In the electromagnetic wave shielding sheet of the present invention, the metal foil is preferably in a wrinkled state. This is because, by being in such a state, the metal foil is not easily cracked only by extending the wrinkles even when bent, and does not emit abnormal noise when bent, and further has excellent design. Such wrinkled state is preferably wrinkled as a result of deformation along the surface of the nonwoven fabric constituting fiber. This is because when the metal foil is deformed along the surface of the nonwoven fabric constituting fiber, the adhesion between the metal foil and the nonwoven fabric is high, and the metal foil and the nonwoven fabric are difficult to peel off.

  The electromagnetic wave shielding sheet of the present invention is provided with a non-woven fabric in addition to the metal foil as described above, whereby the metal foil is reinforced by the non-woven fabric and can be used without being broken even if it is repeatedly bent. The nonwoven fabric is in close contact with the metal foil, and the average fineness of the constituent fibers is preferably 1.5 dtex or more, and more preferably 3 dtex or more so that the metal foil and the nonwoven fabric are not easily peeled even when bent. The upper limit of the average fineness of the constituent fibers is not particularly limited, but is preferably 200 dtex or less. Moreover, the fiber length of the nonwoven fabric constituting fiber is not particularly limited, but may be 1 mm to 100 mm. Further, the nonwoven fabric constituting fiber is not particularly limited, but it is composed of, for example, organic fiber such as polyamide fiber, polyester fiber, polyolefin fiber, acrylic fiber, polyurethane fiber, aromatic polyamide fiber, or inorganic fiber or metal fiber. Can do. In addition, in addition to electromagnetic wave shielding properties, when using fibers with a functional material, such as using a fiber with a flame retardant (for example, antimony oxide, phosphorus compound, etc.) as a nonwoven fabric constituent fiber, Since the derived performance is also retained, it can be easily applied to various applications.

The “average fineness” in the present invention means the sum of the fineness when the number of fibers constituting the nonwoven fabric is one, and the weight average of the fineness of each fiber when the number is two or more. For example, the average fineness of a nonwoven fabric composed of fibers a% with fineness A, fibers b% with fineness B, and fibers c% with fineness C is a value obtained from the following equation.
Average fineness (dtex) = A × a / 100 + B × b / 100 + C × c / 100

  It should be noted that when the polymer water-absorbing powder is thermally bonded to the nonwoven fabric of the present invention, the water-absorbing properties are increased, which is useful as a submarine cable coating material, and when the calcium hydroxide powder is thermally bonded to the nonwoven fabric, self-extinguishing properties can be imparted. Various functional substances can be imparted to the nonwoven fabric.

The basis weight and thickness of the nonwoven fabric constituting the electromagnetic wave shielding sheet of the present invention vary depending on the intended use of the electromagnetic wave shielding sheet, and are not particularly limited. However, the basis weight is preferably 10 to 1000 g / m ² , and the thickness Is preferably 0.1 to 25 mm. In addition, by making the thickness of a nonwoven fabric into 5-25 mm, metal foil may have a through-hole and can provide sound absorption performance to an electromagnetic wave shield sheet.

The electromagnetic wave shielding sheet of the present invention comprises a nonwoven fabric and a metal foil as described above, and the nonwoven fabric is bonded to at least one surface of the metal foil, that is, one surface or both surfaces of the metal foil with an adhesive. Thus, since it adhere | attaches with the adhesive agent, even if it bends, metal foil and a nonwoven fabric peel, or a metal foil is not damaged, It is an electromagnetic wave shield sheet which can be used even if bent. The adhesive is not particularly limited as long as the metal foil and the nonwoven fabric can be firmly bonded to each other, and examples thereof include ethylene-methacrylic acid copolymer, ethylene-acrylic acid ester-maleic anhydride ternary copolymer. Polymers, ionomer resins and the like can be used. Among these, an ethylene-methacrylic acid copolymer can be suitably used because of its excellent adhesiveness to metal. The adhesive may be an emulsion type, a suspension type, a powder type, a film type, a molten film extruded from a T die, or a nonwoven fabric constituting fiber. When the adhesive is an emulsion type, a suspension type, a powder type, a film type, or a molten film extruded from a T die, the amount is 5 to 50 g / m so that the adhesive is excellent and does not peel even when bent. ² is preferred.

  As described above, the electromagnetic wave shielding sheet of the present invention is excellent in air permeability, bendability and electromagnetic wave shielding properties, and therefore can be used as an electromagnetic wave shielding material in various fields. For example, building wall materials, electronic device casing materials, electronic device casing joint members, electronic device cover materials, curtain materials, apron materials, magnetic card holder materials, wallet materials, bag materials such as bags It can be used in various fields such as cable coating materials. In addition, the electromagnetic wave shield sheet can be used in an aspect according to various fields. For example, it can be used in a state of being cut into a tape shape, or can be used in a state of being deformed into a desired shape due to the shape retention of the metal foil.

  An electromagnetic wave shielding sheet comprising one metal foil layer and one nonwoven fabric layer of the present invention can be produced, for example, as follows. First, a metal foil, a nonwoven fabric and an adhesive as described above are prepared. In addition, an adhesive agent is unnecessary when bonding metal foil and a nonwoven fabric by fusing the nonwoven fabric constituent fiber.

  Next, the step of applying an adhesive to the metal foil and / or the nonwoven fabric, laminating the metal foil and the nonwoven fabric via the adhesive on one side of the metal foil, and bonding the metal foil and the nonwoven fabric with the adhesive is performed. To do. Adhesion varies depending on the type of adhesive. In the case of an emulsion type or suspension type, the solvent is adhered by drying and removing, and a powder type, a film type, or a nonwoven fabric constituting fiber is used as the adhesive. In some cases, the adhesive can be bonded by heating to a temperature at which the adhesive melts. Moreover, in the case of the molten film extruded from T-die, after supplying a molten film between metal foil and a nonwoven fabric, it can press and adhere | attach.

  Subsequently, the laminate of the metal foil and the nonwoven fabric is brought into contact with a low hardness pressing material having a hardness (type A durometer hardness test) of 50 or less and the metal foil, and the hardness (type A durometer hardness test) is 90 or more. The electromagnetic wave shielding sheet of the present invention can be manufactured by pressing the high hardness pressing material and the non-woven fabric in contact with each other, and extending the metal foil to disperse the through holes. That is, when a metal foil is pressed with a low-hardness pressing material, the low-hardness pressing material is deformed along the surface of the nonwoven fabric constituting fiber, and the metal foil can be brought into close contact with the nonwoven fabric, while the metal foil is pressed with a low-hardness pressing material. Although the metal foil is not stretchable and is bonded to the nonwoven fabric, it cannot fully follow the deformation caused by the pressing of the low-hardness pressing material, and the metal foil is partially torn. The through holes are scattered. Therefore, the metal foil in the electromagnetic wave shield sheet manufactured by such a method has irregularly scattered through holes whose shapes are not constant, and the metal foil is deformed along the surface of the nonwoven fabric constituting fiber. In a state where wrinkles are expressed. In addition, it is easy to deform | transform along the nonwoven fabric structure fiber surface as the thickness of metal foil is 20 micrometers or less as mentioned above, and it is easy to manufacture the electromagnetic wave shield sheet of the contact | adhered state. Further, when the average fineness of the nonwoven fabric constituting fiber is 1.5 dtex or more, the low-hardness pressing material is likely to be deformed along the surface of the nonwoven fabric constituting fiber, so that the metal foil is also easily deformed along the surface of the nonwoven fabric constituting fiber. It is easy to manufacture an electromagnetic wave shielding sheet in a state of being closely attached.

  This low-hardness pressing material is deformed as described above and has a hardness of 50 or less so that the metal foil can be brought into close contact with the nonwoven fabric and a through-hole can be formed. The lower the hardness is, the better the above effect is. Therefore, it is preferably 40 or less, more preferably 30 or less. On the other hand, when the hardness is less than 1, the deformation of the low-hardness pressing material itself is so large that the low-hardness pressing material does not recover to the original thickness, and therefore it is preferably 3 or more. The shape of such a low hardness pressing material can be, for example, a roll shape, a flat plate shape, or a belt shape. The low-hardness pressing material may be made of any material as long as the above hardness is satisfied, and is not particularly limited, but is preferably made of silicone rubber or foamed silicone rubber.

  On the other hand, since the high hardness pressing material needs to be hard so that the low hardness pressing material is easily deformed, the hardness is 90 or more. In addition, since the high hardness press material should just be hard so that it may not deform | transform, the upper limit of hardness is not specifically limited. The shape of the high-hardness pressing material can be, for example, a roll shape, a flat plate shape, or a belt shape, and need not be the same shape as the low-hardness pressing material. Further, the high-hardness pressing material may be made of any material as long as it satisfies the above hardness, and is not particularly limited, but is preferably made of stainless steel, steel, cotton, viton rubber, or ceramic. In addition, the hardness in this invention means the hardness obtained by the type A durometer hardness test prescribed | regulated to JISK6253.

  The pressing force of the laminate by the low hardness pressing material and the high hardness pressing material is the type of metal foil, the type of nonwoven fabric, the type of low hardness pressing material and the type of high hardness pressing material, the size of the through hole, the number of through holes Alternatively, the pressing force that can disperse the through holes in the metal foil changes depending on the air permeability, and is not particularly limited. This pressing force can be determined by repeating the experiment. The pressing can be performed at room temperature. By adjusting this pressing force, the size of one through hole in the metal foil can be adjusted.

  In addition, the process which adhere | attaches metal foil and a nonwoven fabric by heating at the time of a press, and the process of making a through-hole scatter in metal foil can also be performed simultaneously.

  The above is a method for producing an electromagnetic shielding sheet comprising one metal foil layer and one nonwoven fabric layer. The electromagnetic shielding sheet provided with the nonwoven fabric layers on both sides of the metal foil of the present invention is a nonwoven fabric on one side of the metal foil as described above. After manufacturing an electromagnetic wave shielding sheet having a layer, it can be manufactured by bonding a non-woven fabric to the other surface of the metal foil with an adhesive, and after bonding or simultaneously with bonding, a pair of pressing materials similar to those described above It can be manufactured by pressing. The method of adhering the nonwoven fabric to the other surface of the metal foil with an adhesive and the method of pressing with a pair of pressing materials can be carried out in exactly the same manner as described above.

  In addition, various post-processing can also be implemented so that the electromagnetic wave shielding sheet of this invention may suit various fields. For example, it can be cut into a tape shape, or can be deformed into a desired shape by utilizing the shape retention of the metal foil.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples. The air permeability is a value measured using a Frazier type tester according to JIS L 1096A, and the flexibility is a bending resistance measured using a Gurley type tester according to JIS L 1096A method (Gurley method). The electric field shielding rate is a value at 1000 MHz measured by the KEC method (abbreviation of Kansai Electronics Promotion Industrial Center). The size of the through hole and the number of through holes are the maximum value and the minimum value measured at 10 basic units each consisting of 1 cm square.

Example 1
First, an aluminum foil having a thickness of 9 μm is composed of 100% of a core-sheath type composite fiber A (average fineness: 7.2 dtex, fiber length: 51 mm) having polypropylene as a core component and polyethylene as a sheath component. fusing the dry nonwoven fabric (basis weight: 120 g / ^{m 2,} thickness: 0.35 mm), and ethylene - methacrylic acid copolymer as the sheath component, the core-sheath type composite fibers B which polypropylene as a core component (average fineness: A fiber web (weight per unit area: 15 g / m ² ) composed of 2.4 dtex and fiber length: 5 mm was prepared.

  Subsequently, after interposing a fiber web between the dry nonwoven fabric and the aluminum foil, the dry nonwoven fabric and the dry nonwoven fabric under the conditions of a temperature of 100 ° C. and a pressure of 0.196 MPa by a reliant press machine (JP-1000LTS, manufactured by Asahi Textile Machinery Co., Ltd.) The aluminum foil was bonded.

Next, the dry nonwoven fabric and aluminum foil laminate is formed at room temperature by using a flat low hardness pressing material (hardness: 15) made of foamed silicone rubber and a flat high hardness pressing material (hardness: 100) made of steel. The electromagnetic wave shielding sheet of the present invention was manufactured by pressing at a pressure of 39.2 MPa. The aluminum foil in this electromagnetic wave shielding sheet has wrinkles deformed along the surface of the dry nonwoven fabric constituting fiber, and the aluminum foil has through holes (shape: indeterminate, through hole size: 0.1 to 0.3 mm, The number of through holes: 120 to 180 / cm ² ) was scattered irregularly. The electromagnetic shielding sheet has an air permeability of 9.6 cm ³ / cm ² · s, a bending resistance of 8.9 mN, an electric field shielding ratio of 75.6 dB, and excellent air permeability, flexibility and electromagnetic shielding properties. Met.

(Example 2)
First, an aluminum foil having a thickness of 7 μm, the same dry nonwoven fabric as in Example 1 (weight per unit: 120 g / m ² , thickness: 0.35 mm), and an ethylene-vinyl acetate copolymer fiber manufactured by melt extrusion from a nozzle ( A fiber web (weight per unit area: 20 g / m ² ) having an average fineness: 12 dtex) was prepared.

  Next, after interposing a fiber web between the dry nonwoven fabric and the aluminum foil, the dry nonwoven fabric and the aluminum were conditioned at a temperature of 120 ° C. and a pressure of 0.196 MPa by a Reliant press machine (Asahi Textile Machinery Co., Ltd., JP-1000LTS). The foil was glued.

Next, the dry nonwoven fabric and aluminum foil laminate is formed at room temperature by using a flat low hardness pressing material (hardness: 15) made of foamed silicone rubber and a flat high hardness pressing material (hardness: 100) made of steel. The electromagnetic wave shielding sheet of the present invention was manufactured by pressing at a pressure of 39.2 MPa. The aluminum foil in this electromagnetic wave shielding sheet has wrinkles deformed along the surface of the dry nonwoven fabric constituting fiber, and the aluminum foil has through holes (shape: indeterminate, through hole size: 0.1 to 0.3 mm, The number of through-holes: 100 to 160 holes / cm ² ) was scattered irregularly. The electromagnetic shielding sheet has an air permeability of 11.3 cm ³ / cm ² · s, a bending resistance of 10.5 mN, an electric field shielding ratio of 75.4 dB, and excellent air permeability, flexibility and electromagnetic shielding properties. Met.

(Example 3)
First, an adhesive comprising an aluminum foil having a thickness of 7 μm, the same dry nonwoven fabric as in Example 1 (weight per unit: 120 g / m ² , thickness: 0.35 mm), and an ethylene-acrylate-maleic anhydride terpolymer. A film (weight per unit area: 20 g / m ² , thickness: 20 μm) was prepared.

  Next, after interposing an adhesive film between the dry nonwoven fabric and the aluminum foil, the dry nonwoven fabric and the dry nonwoven fabric were conditioned at a temperature of 115 ° C. and a pressure of 0.196 MPa using a Reliant press machine (JP-1000LTS, manufactured by Asahi Textile Machinery Co., Ltd.). The aluminum foil was bonded.

Next, the dry nonwoven fabric and aluminum foil laminate is formed at room temperature by using a flat low hardness pressing material (hardness: 15) made of foamed silicone rubber and a flat high hardness pressing material (hardness: 100) made of steel. Then, the electromagnetic wave shielding sheet of the present invention was manufactured by pressing at a pressure of 49 MPa. The aluminum foil in this electromagnetic wave shielding sheet has wrinkles deformed along the surface of the dry nonwoven fabric constituting fiber, and the aluminum foil has through holes (shape: indeterminate, through hole size: 0.1 to 0.2 mm, The number of through-holes: 30 to 100 / cm ² ) was scattered irregularly. The electromagnetic shielding sheet has an air permeability of 6.2 cm ³ / cm ² · s, a bending resistance of 13.5 mN, an electric field shielding ratio of 75.7 dB, and has excellent air permeability, flexibility and electromagnetic shielding properties. Met.

(Comparative Example 1)
First, an aluminum foil having a thickness of 7 μm, composed of 100% of core-sheath type composite fiber A (average fineness: 7.2 dtex, fiber length: 51 mm) having polypropylene as a core component and polyethylene as a sheath component, Core-sheath type composite fiber B (average fineness: average fiber size) having a fused dry nonwoven fabric (weight per unit: 120 g / m ² , thickness: 0.35 mm) and ethylene-methacrylic acid copolymer as a sheath component and polypropylene as a core component. A fiber web (weight per unit area: 15 g / m ² ) composed of 2.4 dtex and fiber length: 5 mm was prepared.

Then, after interposing a fiber web between the dry nonwoven fabric and the aluminum foil, the dry nonwoven fabric and the dry nonwoven fabric under the conditions of a temperature of 100 ° C. and a pressure of 0.196 MPa by a reliant press machine (JP-1000LTS, manufactured by Asahi Textile Machinery Co., Ltd.) An aluminum foil was bonded to obtain an electromagnetic wave shielding sheet. In this electromagnetic wave shielding sheet, the aluminum foil was deformed along the surface of the dry nonwoven fabric constituting fiber, but the aluminum foil had no through holes. The electromagnetic shielding sheet has an air permeability of 0 cm ³ / cm ² · s, a bending resistance of 10.2 mN, and an electric field shielding ratio of 76.4 dB, which is excellent in flexibility and electromagnetic shielding properties, but has no air permeability. It was easy to condense.

(Comparative Example 2)
After impregnating an acrylic ester binder emulsion with a 9 μm thick aluminum foil and a fiber web (weight per unit: 150 g / m ² ) made of polyethylene terephthalate fiber (average fineness: 6.0 dtex, fiber length: 51 mm), the temperature is 145 ° C. ^Two dry nonwoven fabrics (weight per unit area: 200 g / m ² , thickness: 1.4 mm) prepared by heat treatment for 5 minutes and heat crosslinking were prepared.

Next, after sandwiching the aluminum foil between the dry nonwoven fabrics, through holes were made by a needle punch machine, and the dry nonwoven fabric and the aluminum foil were integrated to obtain an electromagnetic wave shielding sheet. Through holes (shape: triangle, size of through holes: 0.4 to 0.7 mm, number of through holes: 3 to 7 / cm ² ) were scattered irregularly in the aluminum foil of this electromagnetic wave shielding sheet. . Note that the air permeability of the electromagnetic wave shielding sheet 1.9cm ³ / ^cm 2 · s, stiffness is 54 mN, the electric field shielding factor has breathable 75.3DB, although excellent in electromagnetic shielding, The adhesive strength between the dry nonwoven fabric and the aluminum foil was insufficient, and it was easily peeled off simply by bending. Moreover, when pulling and bending are repeated, the nonwoven fabric is deformed, but the aluminum foil cannot follow the deformation and is torn.

Claims (5)

An electromagnetic wave shielding sheet comprising a metal foil and a non-woven fabric, wherein the non-woven fabric is bonded to at least one side of the metal foil with an adhesive, and through holes are scattered in the metal foil. Shield sheet. 2. The electromagnetic wave shielding sheet according to claim 1, wherein the metal foil is in a wrinkled state. The electromagnetic wave shielding sheet according to claim 1 or 2, wherein the metal foil has a thickness of 20 µm or less. The electromagnetic wave shielding sheet according to any one of claims 1 to 3, wherein the nonwoven fabric constituting fibers have an average fineness of 1.5 dtex or more. The process of adhering the non-woven fabric with an adhesive to one side of the metal foil, the low hardness pressing material having a hardness (type A durometer hardness test) of 50 or less, and the metal foil abut, and the hardness (type A durometer hardness test) is The manufacturing method of the electromagnetic wave shielding sheet characterized by including the process which presses in the state which 90 or more high-hardness pressing material and a nonwoven fabric contact | abut, and extends metal foil and makes a through-hole scatter.