Electromagnetic wave shielding molded film, manufacturing method of molded body, and manufacturing method of electromagnetic wave shielding molded film

Abstract

To provide a molding film for an electromagnetic wave shield excellent in moldability and electromagnetic wave shield property, a method for manufacturing a molded body, and a method for manufacturing a molding film for an electromagnetic wave shield.SOLUTION: A molding film for an electromagnetic wave shield contains a layer A containing 60 mass% or more and 91 mass% or less of particles and 9 mass% or more and 40 mass% or less of an urethane resin when the whole components constituting the layer A are 100 mass%, in which an average particle diameter of the particles is 0.01 μm or more and less than 3.0 μm, and a surface resistance value of the layer A is 1.0×101 Ω / sq. or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic wave shielding molded film, a method for producing a molded product, and a method for producing an electromagnetic wave shielding molded film. [Background technology]

[0002] In recent years, with the expansion of the IoT society, there has been an increasing demand for electromagnetic wave shielding performance in fields such as mobile phones, electrical appliances, and automobile parts. When using resin for housings, known methods include plating or conductive coating of the molded body. However, these conventional methods require environmental measures such as wastewater treatment and post-treatment of solvents, and various attempts have been made to improve this aspect.

[0003] For example, Patent Document 1 discloses a technique for insert injection molding a thin film sheet having a conductive layer, and Patent Document 2 discloses a technique for TOM molding a laminated film, in which a conductive layer is pre-laminated on a base film, onto a molded body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-175243 [Patent Document 2] Japanese Patent Publication No. 2020-094170 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the techniques described in Patent Documents 1 and 2 have limitations in terms of the shape of the molded body that can be applied, since cracks and tears may occur in the conductive layer and the base film if the molded body has a complex shape.

[0006] An object of the present invention is to improve upon the problems of the prior art and to provide an electromagnetic wave shielding molded film that is excellent in formability and electromagnetic wave shielding properties, a method for producing a molded product, and a method for producing an electromagnetic wave shielding molded film. [Means for solving the problem]

[0007] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have found that the problems can be solved as follows, and have arrived at the present invention. That is, preferred embodiments of the electromagnetic wave shielding molded film, the method for producing a molded product, and the method for producing an electromagnetic wave shielding molded film of the present invention have the following configurations.

[0008] (1) Layer A contains particles in an amount of 60% by mass or more and 91% by mass or less and urethane resin in an amount of 9% by mass or more and 40% by mass or less, where the total mass of all components constituting Layer A is taken as 100% by mass, and the particles have an average particle size of 0.01 μm or more and less than 3.0 μm, and the surface resistivity of Layer A is 1.0 × 10 1 Molded film for electromagnetic wave shielding with a resistance of Ω / □ or less.

[0009] (2) The molded film for electromagnetic wave shielding according to (1), wherein the electromagnetic wave shielding effect is 40 dB or more when measured using the KEC method (electric field) for electromagnetic waves of a frequency of 1 GHz when the layer A is stretched to 1.41 times its length and 1.41 times its width.

[0010] (3) The electromagnetic wave shielding molded film according to (1) or (2), which has the layer A and a substrate film.

[0011] (4) The electromagnetic wave shielding molded film according to (3), wherein the base film contains 50% by mass or more and 99% by mass or less of a cyclic olefin resin relative to 100% by mass of the entire base film.

[0012] (5) The electromagnetic wave shielding molded film according to (3) or (4), which comprises an adhesive layer, the layer A, and the base film in this order, and the adhesive layer is the outermost layer. (6) The electromagnetic wave shielding molded film according to (3) or (4), which comprises an adhesive layer, the base film, and the layer A in this order. (7) A method for producing a molded article, comprising a step of attaching the electromagnetic wave shielding molded film according to any one of (3) to (6) to an article to be molded.

[0013] (8) A method for producing a molded body, comprising the steps of: attaching the electromagnetic wave shielding molded film according to any one of (3) to (5) to a molded body; and peeling off the base film, in this order.

[0014] (9) A method for producing an electromagnetic wave shielding molded film according to any one of (3) to (6), comprising the steps of applying Layer A and an adhesive layer, in this order, to at least one surface of the base film by dip coating, roller coating, wire bar coating, gravure coating, screen printing, comma coating, or die coating, and then subjecting the base film coated with Layer A and the adhesive layer to a heat treatment. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an electromagnetic wave shielding molded film having excellent moldability and electromagnetic wave shielding properties, a method for producing a molded product, and a method for producing an electromagnetic wave shielding molded film. DETAILED DESCRIPTION OF THE INVENTION

[0016] A preferred embodiment of the electromagnetic wave shielding molded film of the present invention comprises Layer A containing particles in an amount of 60% by mass or more and 91% by mass or less and a urethane resin in an amount of 9% by mass or more and 40% by mass or less, where the total mass of all components constituting Layer A is taken as 100% by mass, and the particles have an average particle size of 0.01 μm or more and less than 3.0 μm, and the surface resistivity of Layer A is 1.0 × 10 1The electromagnetic wave shielding molded film has a resistivity of Ω / □ or less. By adopting such an embodiment, the electromagnetic wave shielding molded film has excellent moldability and electromagnetic wave shielding properties after molding. The electromagnetic wave shielding molded film of the present invention will be specifically described below.

[0017] [Layer A] In the present invention, a preferred embodiment of Layer A contains particles in an amount of 60% by mass to 91% by mass and urethane resin in an amount of 9% by mass to 40% by mass, where the total mass of all components constituting Layer A is taken as 100% by mass. By adopting such a configuration, even when stretched during molding, fine cracks do not occur, resulting in excellent moldability. Furthermore, the surface resistivity of Layer A is 1.0 × 10 1 By having a resistivity of Ω / □ or less, even when stretched by molding, fine cracks that would impair the electromagnetic shielding properties do not occur, and the electromagnetic shielding properties after molding can be excellent. In this case, some of the particles play a role in forming a conductive path after molding, but even if Layer A is conductive, if fine cracks are present, the electromagnetic shielding properties may not be sufficient. By adopting the above-mentioned embodiment, even when stretched by molding, fine cracks that would impair the electromagnetic shielding properties do not occur, and the electromagnetic shielding properties after molding can be excellent.

[0018] From the above viewpoint, the content of particles is preferably 60% by mass or more, and more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, to improve the electromagnetic wave shielding properties after molding.

[0019] Furthermore, by containing 91% by mass or less of the particles, the component ratio of the urethane resin can be increased, thereby improving moldability. From the same viewpoint, the content is more preferably 87% by mass or less, and even more preferably 85% by mass or less.

[0020] From the above viewpoints, the particles in the present invention preferably contain 65% by mass or more and 87% by mass or less, and even more preferably 70% by mass or more and 85% by mass or less, when all components constituting Layer A are taken as 100% by mass.

[0021] From the viewpoint of improving moldability and electromagnetic wave shielding properties after molding, the particles in the present invention preferably contain one or more types selected from metal powders of gold, silver, copper, nickel, chromium, palladium, indium, aluminum, zinc, platinum, etc., plated metal powders of these metals, alloys of these metals, inorganic powders coated with these metals, and carbon particles, and more preferably contain particles containing a zero-valent metal. From the viewpoint that the lower the resistivity, the better the electromagnetic wave shielding properties, it is even more preferable to contain one or more types selected from gold, silver, silver-plated copper powder, and silver-copper alloys.

[0022] Whether or not the particles listed above contain a zero-valent metal element can be determined by performing energy dispersive X-ray spectroscopy mapping analysis (hereinafter referred to as EDX mapping analysis) on a cross section obtained by cutting the EMI shielding molded film and determining whether or not a zero-valent metal element is detected in the particle portion. EDX mapping analysis can be performed, for example, using a scanning electron microscope (FEI, XL30 SFEG) equipped with an energy dispersive X-ray spectrometer (EDAX, NEW XL30 132-2.5) at an acceleration voltage of 20 kV and a magnification of 20,000x. The EMI shielding molded film can be cut using a "Cross Section Polisher" (registered trademark) SM-09010 (JEOL), or similar. When using this device, samples are obtained by treating the sample with argon gas at an acceleration voltage of 4 kV and a current of 70 μA for 10 hours. Regarding carbon particles, this refers to particles that have been qualitatively analyzed by performing microscopic Raman mapping analysis on a cross section obtained using the same method as above. The microscopic Raman mapping analysis can be performed using, for example, a microscopic laser Raman spectrometer (manufactured by Horiba, Ltd., "LabRAM" (registered trademark) HR Evolution).

[0023] The thickness of Layer A of the present invention is preferably 5 μm or more and 50 μm or less from the viewpoint of satisfying moldability, processability, and electromagnetic wave shielding properties after molding. Having a thickness of Layer A of 50 μm or less can reduce thermal expansion of Layer A in the electromagnetic wave shielding molded film, thereby improving processability. From the same viewpoint, the thickness of Layer A is more preferably 40 μm or less, and even more preferably 30 μm or less. Furthermore, having a thickness of Layer A of 5 μm or more allows the performance of the urethane resin to be fully exhibited, and allows for sufficient moldability and electromagnetic wave shielding properties after molding. From the same viewpoint, the thickness of Layer A is more preferably 10 μm or more.

[0024] The average particle size of the particles is preferably 0.01 μm or more and less than 3.0 μm from the viewpoint of improving moldability and electromagnetic wave shielding properties after molding. By setting the average particle size of the particles to 0.01 μm or more, the conductivity between particles in Layer A is increased, thereby improving electromagnetic wave shielding properties. From the same viewpoint, the average particle size of the particles is more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. Furthermore, by setting the average particle size of the particles to less than 3.0 μm, the dispersibility of the particles in Layer A can be improved, thereby suppressing the occurrence of cracks in Layer A when molding the electromagnetic wave shielding molded film and improving moldability. Furthermore, even when stretched by molding, fine cracks that would impair the electromagnetic wave shielding properties do not occur, thereby ensuring excellent electromagnetic wave shielding properties after molding. From the same viewpoint, the average particle size of the particles is more preferably 2.0 μm or less, and even more preferably 1.5 μm or less.

[0025] From the above viewpoint, the average particle size of the particles in the present invention is more preferably 0.05 μm or more and 2.0 μm or less, and even more preferably 0.1 μm or more and 1.5 μm or less.

[0026] The average particle size was determined by observing the cross section of layer A at 100,000x magnification using a scanning electron microscope (XL30 SFEG, manufactured by FEI) on a cross section obtained by cutting the electromagnetic wave shielding molded film, and calculating the particle size distribution of the particles present in layer A from the cross section photograph using image analysis software (Image-Pro Plus, manufactured by Nippon Rover Co., Ltd.). Specifically, the diameters (equivalent diameter of a circle with an area) of 200 or more particles randomly selected from the cross section photograph were measured, and a number-based particle size distribution was obtained by plotting the particle diameter on the horizontal axis and the particle abundance ratio on the vertical axis. In the number-based particle size distribution, the particle diameter on the horizontal axis is expressed in 10-nm intervals starting from 0 nm, and the particle abundance ratio on the vertical axis is expressed by the formula "abundance ratio = total number of detected particles with the corresponding particle size / total number of all detected particles." The average particle size at the peak top showing the maximum in the particle abundance ratio chart obtained above was determined. When there are multiple peaks, the peak with the largest vertical axis among the peaks is taken as the average particle size. For example, when the particle size range showing the largest vertical axis peak is 250 nm to 260 nm, the upper limit of the range is adopted as the average particle size value, so that the average particle size value is 260 nm.

[0027] From the viewpoint of improving moldability and electromagnetic wave shielding properties after molding, the aspect ratio of the particles is preferably from 1 to less than 3. The particle shape may be spherical, globular, elliptical, ovoid, kidney-shaped, or the like, and may be used alone or in combination.

[0028] Furthermore, from the viewpoint of improving moldability and electromagnetic wave shielding properties after molding, the particles preferably include insulating particles, and more preferably the particles include at least one selected from metal powders such as gold, silver, copper, nickel, chromium, palladium, indium, aluminum, zinc, and platinum, plated metal powders of these metals, alloys of these metals, inorganic powders coated with these metals, and carbon particles. From the viewpoint of improving moldability and electromagnetic wave shielding properties after molding, Layer A of the present invention preferably contains insulating particles in an amount of 1% by mass to 10% by mass, where the total components constituting Layer A is taken as 100% by mass. By including insulating particles in an amount of 1% by mass or more, the dispersibility of the particles in the urethane resin can be improved, suppressing cracking in Layer A during molding of the electromagnetic wave shielding molded film, thereby improving moldability. Furthermore, by including insulating particles in an amount of 10% by mass or less, the ratio of particles and urethane resin to the total components constituting Layer A can be increased, thereby improving electromagnetic wave shielding properties after molding. By adopting such a configuration, it is possible to easily achieve an electromagnetic wave shielding effect of 40 dB or more when measured using the KEC method (electric field) for electromagnetic waves with a frequency of 1 GHz when Layer A is stretched 1.41 times vertically and 1.41 times horizontally.

[0029] From the viewpoint of dispersibility in urethane resin, it is preferable to use metal oxides such as silica, alumina, titania, etc., or inorganic powders coated with these metal oxides as insulating particles, and these refer to particles whose elements listed above have been qualitatively analyzed using EDX mapping analysis, which is the same method as for the particles.

[0030] The insulating particles preferably have an average particle size of 0.001 μm or more and 1.0 μm or less, from the viewpoint of improving moldability and electromagnetic wave shielding properties.

[0031] By setting the average particle diameter of the insulating particles to 0.001 μm or more, the dispersibility of the particles in the urethane resin can be improved, thereby improving moldability. From the same perspective, it is more preferable to set the average particle diameter of the insulating particles to 0.005 μm or more, and even more preferable to set it to 0.01 μm or more. Furthermore, by setting the average particle diameter of the insulating particles to 1.0 μm or less, the conductivity between particles in Layer A is increased, thereby improving electromagnetic wave shielding properties. From the same perspective, it is more preferable to set the average particle diameter of the insulating particles to 0.5 μm or less, and even more preferable to set it to 0.1 μm or less.

[0032] The average particle size of the insulating particles can be determined in the same manner as the average particle size of the particles.

[0033] From the viewpoint of improving moldability and electromagnetic wave shielding properties after molding, the aspect ratio of the insulating particles is preferably from 1 to less than 3. The insulating particles may be spherical, globular, elliptical, ovoid, kidney-shaped, or the like, and may be used alone or in combination.

[0034] [Urethane resin] In the present invention, from the viewpoint of satisfying both moldability and electromagnetic wave shielding properties after molding, the urethane resin content is preferably 9% by mass or more and 40% by mass or less, where the total mass of all components constituting Layer A is taken as 100% by mass. By containing 9% by mass or more of the urethane resin, it is possible to improve the dispersibility of particles in Layer A and the moldability and flexibility of Layer A as a whole, thereby improving the moldability as an electromagnetic wave shielding molded film. From the same viewpoint, it is more preferable that the urethane resin content be 10% by mass or more, and even more preferable that the urethane resin content be 13% by mass or more.

[0035] Furthermore, by containing 40% by mass or less of a urethane resin, the ratio of particles to all components constituting Layer A can be increased, thereby improving the electromagnetic wave shielding properties after molding. From the same viewpoint, a content of 25% by mass or less is more preferable, and a content of 20% by mass or more is even more preferable.

[0036] From the above viewpoints, when all components constituting Layer A are taken as 100% by mass, the urethane resin in the present invention preferably contains 10% by mass or more and 25% by mass or less of urethane resin, and even more preferably contains 13% by mass or more and 20% by mass or less of urethane resin.

[0037] From the viewpoint of improving the dispersibility of particles in Layer A and the moldability and flexibility of Layer A as a whole, and improving the moldability and electromagnetic shielding properties after molding as an electromagnetic wave shielding molded film, it is preferable to use urethane resins containing acrylic resin and / or acrylic component as a copolymer component, urethane resins containing polyester resin and / or polyester component as a copolymer component, urethane resins containing epoxy resin and / or epoxy component as a copolymer component, urethane resins containing polyamine and / or amine component as a copolymer component, urethane resins containing alkyd resin and / or alkyd component as a copolymer component, ester-based urethane resins, and ether-based urethane resins, either alone or in combination; and from the same viewpoint, it is even more preferable to use urethane resins containing acrylic resin and / or acrylic component as a copolymer component, and urethane resins containing polyester resin and / or polyester component as a copolymer component, either alone or in combination.

[0038] One method for qualitative and quantitative analysis of urethane resins is to scrape off only layer A from a molded film for electromagnetic wave shielding, freeze-dry the resulting sample of layer A, and then perform qualitative and quantitative analysis of the recovered dried material using gas chromatography mass spectrometry (P&T-GC / MS) equipped with a purge and trap sampler (thermal desorption device).

[0039] [Surface resistance value / electromagnetic wave shielding] The electromagnetic wave shielding molded film of the present invention includes Layer A containing particles in an amount of 60% by mass or more and 91% by mass or less when all components constituting Layer A are taken as 100% by mass, and the surface resistance of Layer A is 1.0 × 10 1It is preferable that the resistance is Ω / □ or less. By adopting such a form, when stretched by molding processing, the electromagnetic wave shielding effect can be made 40 dB or more when measured using the KEC method (electric field) for electromagnetic waves with a frequency of 1 GHz.

[0040] As described above, the above-described embodiment can be achieved by including Layer A containing 60% to 91% by mass of particles and 9% to 40% by mass of a urethane resin, where the total mass of all components constituting Layer A is taken as 100% by mass, and the particles have an average particle size of 0.01 μm to less than 3.0 μm, and the particles include one or more selected from metal powders of gold, silver, copper, nickel, chromium, palladium, indium, aluminum, zinc, platinum, etc., plated metal powders of these metals, alloys of these metals, inorganic powders coated with these metals, and carbon particles. Among these, the layer A more preferably contains 65% to 87% by mass, and even more preferably 70% to 85% by mass, of particles of one or more selected from metal powders of gold, silver, copper, nickel, chromium, palladium, indium, aluminum, zinc, platinum, etc., plated metal powders of these metals, alloys of these metals, metal oxides of these metals, inorganic powders coated with these metals, and carbon particles.

[0041] In the electromagnetic wave shielding molded film of the present invention, the surface resistance of Layer A is 1.0 × 10 1 By making the surface resistance Ω / □ or less, the conductivity between particles in Layer A is high, and the electromagnetic wave shielding property can be improved. The surface resistance value of Layer A can be determined by the method described in the examples.

[0042] The KEC method, established by the Kansai Electronics Industry Development Center, evaluates the shielding effectiveness of electromagnetic waves generated in the near field by separating them into electric and magnetic fields. Measurements using this method can be performed by transmitting electromagnetic waves from a transmitting antenna (transmitting fixture) through an electromagnetic shielding film (measurement sample) and receiving them with a receiving antenna (receiving fixture). The KEC method measures the electromagnetic waves that pass through (transmitted by) the electromagnetic shielding film at the receiving antenna. In other words, it measures how much the transmitted electromagnetic waves (signal) are attenuated by the electromagnetic shielding film at the receiving antenna side. Therefore, the electromagnetic shielding ability to block (shield) electromagnetic waves can be determined by combining the reflective component that reflects the electromagnetic waves and the absorbing component that absorbs the electromagnetic waves.

[0043] The electromagnetic wave shielding molded film of the present invention preferably has an electromagnetic wave shielding effect of 40 dB or more when Layer A is stretched 1.41 times vertically and 1.41 times horizontally, as measured by the KEC method (electric field) for electromagnetic waves with a frequency of 1 GHz. This embodiment makes it possible to impart an excellent electromagnetic wave shielding effect when the electromagnetic wave shielding molded film of the present invention is used for molding, and to increase the degree of freedom in the shape of the molding and the processability of the molding step.

[0044] [Base film] One embodiment of the electromagnetic wave shielding molded film of the present invention includes a substrate film having the above-mentioned Layer A. From the viewpoint of achieving both moldability and processability, the substrate film used in the present invention preferably contains 50% by mass or more and 99% by mass or less of a cyclic olefin resin relative to 100% by mass of the entire substrate film.

[0045] By containing 50% by mass or more of a cyclic olefin resin, the elastic modulus of the substrate film can be significantly reduced during molding processing, thereby improving the moldability of the electromagnetic wave shielding molded film. From the same viewpoint, a content of 60% by mass or more is more preferable, and a content of 70% by mass or more is even more preferable.

[0046] Furthermore, by containing 99% by mass or less of a cyclic olefin resin, the brittleness of the base film can be reduced, and defects such as film breakage during processing of Layer A can be reduced, thereby improving processability during application of Layer A. From the same viewpoint, the content is more preferably 97% by mass or less, and even more preferably 95% by mass or less.

[0047] From the above viewpoints, the cyclic olefin resin in the base film of the present invention preferably contains 60% by mass or more and 97% by mass or less of the cyclic olefin resin, and even more preferably 75% by mass or more and 95% by mass or less of the cyclic olefin resin, relative to 100% by mass of the entire base film.

[0048] Here, the term "cyclic olefin resin" refers to a resin having an alicyclic structure in the polymer main chain, and containing a total of 50% to 100% by mass of components derived from cyclic olefin monomers per 100% by mass of the polymer. Here, the term "cyclic olefin monomer" refers to a hydrocarbon compound having a cyclic structure formed by carbon atoms and having a carbon-carbon double bond in the cyclic structure. From the viewpoints of productivity and surface appearance when the film is used for decoration, bicyclo[2,2,1]hept-2-ene (hereinafter referred to as "norbornene"), cyclopentadiene, 1,3-cyclohexadiene, and derivatives thereof are preferably used as the cyclic olefin monomer, with norbornene being more preferred.

[0049] As long as the above requirements are satisfied, the cyclic olefin resin in the present invention may be any of a resin obtained by polymerizing only one type of cyclic olefin monomer, a resin obtained by copolymerizing multiple types of cyclic olefin monomers, and a resin obtained by copolymerizing one or more types of cyclic olefin monomers with one or more types of chain olefin monomers. Here, the chain olefin monomer refers to a hydrocarbon compound having a carbon-carbon double bond and not having a cyclic structure formed by carbon atoms. The combination of the cyclic olefin monomer and the chain olefin monomer is not particularly limited as long as it does not impair the effects of the present invention. A single type of cyclic olefin resin may be used, or multiple types may be used in combination. When multiple types of cyclic olefin resins are used in combination, the content of the cyclic olefin resin is calculated by adding together all the cyclic olefin resins.

[0050] [Adhesive layer] One embodiment of the electromagnetic wave shielding molded film of the present invention has an adhesive layer, Layer A, and the base film in this order. From the viewpoint of adhering Layer A to the body to be molded, it is preferable that the adhesive layer, Layer A, and the base film are present in this order, with the adhesive layer being the outermost layer. Here, the adhesive layer serves to adhere Layer A, which has been transferred to the body to be molded, to the body to be molded, and refers to a layer that has an adhesive strength of 5 N / 10 mm or more when Layer A is forcibly peeled off from the body to be molded at 180° using a tensile tester (manufactured by Orientec Co., Ltd., "Tensilon" (registered trademark) UCT-100).

[0051] The resin used in the adhesive layer in the electromagnetic wave shielding molded film of the present invention, i.e., the resin contained in the adhesive layer, is used for the purpose of imparting adhesion to the molded body to Layer A. For this purpose, heat-sensitive resins or pressure-sensitive resins can be used as materials suitable for the resin contained in the adhesive layer, and the material for the adhesive layer can be selected appropriately depending on the material of the molded body.

[0052] The resin contained in the adhesive layer is preferably, for example, an acrylic resin, a polyester resin, a polyphenylene oxide-polystyrene resin, a polycarbonate resin, a polystyrene resin, a styrene copolymer resin, a polyamide resin, a chlorinated polyolefin resin, a chlorinated ethylene-vinyl acetate copolymer resin, a cyclized rubber, a coumarone-indene resin, or the like, used alone or in combination, but is not limited to these, as long as the effects of the present invention are not impaired.

[0053] [Molded film for electromagnetic wave shielding] The electromagnetic wave shielding molded film of the present invention has excellent moldability and electromagnetic wave shielding properties, making it possible to easily add an electromagnetic wave shielding layer to a molded body having, for example, a curved surface, uneven ribs, hinges, bosses, or hollow shapes.

[0054] From the above viewpoint, the applications are not limited as long as the effects of the present invention are not impaired. For example, the composition can be suitably used to impart electromagnetic wave shielding properties to personal computers, displays, office automation equipment, mobile phones, personal digital assistants, optical equipment, audio equipment, air conditioners, lighting equipment, entertainment equipment, toys, other home appliances, electronic equipment, semiconductor materials, electrical components and internal parts of automobiles, electrical components and internal parts of aircraft, electrical components and internal parts of motorcycles, etc.

[0055] The electromagnetic wave shielding molded film of the present invention preferably has Layer A and a base film, and when the electromagnetic wave shielding layer is added to the molded body without leaving the base film after molding processing, it is more preferable that the adhesive layer, Layer A, and base film are present in this order, with the adhesive layer being the outermost layer, from the viewpoint of adhering the electromagnetic wave shielding layer to the molded body.

[0056] When an electromagnetic wave shielding layer is added to the molded body together with a base film after molding processing, it is more preferable to have an adhesive layer, the base film, and layer A in this order from the viewpoint of adhering the base film to the molded body.

[0057] In the present invention, the base film may have Layer A on both sides or only one side, but from the viewpoint of adhering Layer A or the base film to the molded body, it is preferable to have Layer A on only one side.

[0058] [Manufacturing method for electromagnetic wave shielding molded film] The method for producing the electromagnetic wave shielding molded film of the present invention can include, for example, the following exemplary materials, amounts used, treatment contents, treatment procedures, etc.

[0059] The electromagnetic wave shielding molded film of the present invention can be produced, for example, by applying the resin composition of Layer A and the resin composition of the adhesive layer in this order to at least one surface of a substrate film, and then subjecting the film to a heat treatment.

[0060] The resin composition of Layer A of the present invention can be obtained by mixing particles, a urethane resin, and an organic solvent for mixing to obtain a resin mixture, and then mixing with an organic solvent for dilution.

[0061] The particles used in the resin mixture of the present invention preferably account for 60% by mass or more and 91% by mass or less of the total components constituting Layer A, taking the total mass of all components constituting Layer A as 100%. The particles also preferably have an average particle size of 0.01 μm or more and less than 3.0 μm, as calculated by laser diffraction / scattering particle size distribution measurement. Examples of devices used for laser diffraction / scattering particle size distribution measurement include a scattering particle size distribution measurement device (LA950, manufactured by Horiba, Ltd.).

[0062] The urethane resin used in the resin mixture of Layer A of the present invention preferably contains 9% by mass or more and 40% by mass or less of urethane resin when all components constituting Layer A are taken as 100% by mass.

[0063] The mixing organic solvent used in the resin mixture of Layer A of the present invention is preferably 5% by mass or more and 50% by mass or less, from the viewpoint of achieving good mixing and dispersion of the particles and the urethane resin, when the total components of the resin mixture comprising the particles, urethane resin, and mixing organic solvent are taken as 100% by mass. From the viewpoint of suppressing the evaporation of the organic solvent for mixing when mixing the particles and the urethane resin and suppressing the thickening of the conductive paste, it is more preferable to use, alone or in combination, the following organic solvents for mixing: N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethyl sulfoxide, γ-butyrolactone, ethyl lactate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate (hereinafter referred to as "DMEA"), diethylene glycol monobutyl ether, diethylene glycol, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0064] The dilution organic solvent used in the resin composition of Layer A of the present invention is preferably 10% by mass or more and 80% by mass or less, based on 100 mass of the total components of the resin composition constituted by the resin mixture and the dilution organic solvent, from the viewpoint of achieving both coatability when the resin composition of Layer A is applied to a substrate film and the thickness of Layer A. Examples of the mixing organic solvent include ethyl methyl ketone, methyl isobutyl ketone, butyl acetate, ethyl acetate, methanol, isopropanol, cyclohexanone, toluene, and xylene.

[0065] In the resin mixture of Layer A of the present invention, the particles, urethane resin, and mixing organic solvent can be mixed using any known mixing and dispersing method, such as a three-roll mill, ultrasonic disperser, sand mill, attritor, pearl mill, super mill, ball mill, impeller, desparger, KD mill, colloid mill, dynatron, planetary mill, or pressure kneader.

[0066] In the resin composition of Layer A of the present invention, the resin mixture and the organic solvent for dilution can be mixed using known mixing and dispersing methods such as a magnetic stirrer, a homodisper, ultrasonic irradiation, vibration dispersion, and manual mixing and dispersion.

[0067] The resin composition for the adhesive layer of the present invention can be obtained by mixing an adhesive layer resin, such as an acrylic resin, a polyester resin, a polyphenylene oxide-polystyrene resin, a polycarbonate resin, a polystyrene resin, a styrene copolymer resin, a polyamide resin, a chlorinated polyolefin resin, a chlorinated ethylene-vinyl acetate copolymer resin, a cyclized rubber, or a coumarone-indene resin, alone or in combination, with a diluent organic solvent. Examples of diluent organic solvents include ethyl methyl ketone, methyl isobutyl ketone, butyl acetate, ethyl acetate, methanol, isopropanol, cyclohexanone, toluene, and xylene. The adhesive layer resin and the diluent organic solvent can be mixed using known mixing and dispersion methods such as a magnetic stirrer, a homodisperser, ultrasonic irradiation, vibration dispersion, and manual mixing and dispersion.

[0068] As a method for applying the resin composition of Layer A and the resin composition of the adhesive layer in this order to at least one surface of the base film, it is preferred to form Layer A and the adhesive layer by coating using a comma coating method, applicator method, dip coating method, roller coating method, wire bar coating method, reverse coating method, kiss coating method, gravure coating method, die coating method (U.S. Pat. No. 2,681,294), etc., and from the viewpoint of processability, the applicator method, comma coating method, reverse coating method, and die coating method are more preferred.

[0069] [Object to be molded] Examples of the molded body of the present invention include components containing resins such as polypropylene, acrylic, polystyrene, polyacrylonitrile-styrene, and polyacrylonitrile-butadiene-styrene (ABS), components in which carbon fiber or glass fiber is impregnated or mixed and dispersed in these resins, and components whose main component is glass.

[0070] [Method for manufacturing molded body] In the case where an electromagnetic wave shielding layer is added to a molded body together with a substrate film after the molding process of the present invention, a preferred method for producing the molded body is a production method including a step of attaching the electromagnetic wave shielding molded film of the present invention to the molded body.

[0071] In order to easily attach the electromagnetic shielding molded film of the present invention to a molded body in the step of attaching the electromagnetic shielding molded film of the present invention to a molded body, the electromagnetic shielding molded film of the present invention preferably has, in this order, an adhesive layer, the base film, and Layer A. Use of such an electromagnetic shielding molded film makes it easy to attach the electromagnetic shielding molded film with the adhesive layer facing the molded body.

[0072] On the other hand, in the case where an electromagnetic wave shielding layer is added to a molded body without leaving a base film after the molding process of the present invention, a manufacturing method for the molded body preferably includes a step of attaching the electromagnetic wave shielding molded film of the present invention to the molded body, and a step of peeling off the base film, in this order.

[0073] In order to easily attach the electromagnetic shielding molded film of the present invention to the body to be molded in the step of attaching the electromagnetic shielding molded film of the present invention to the body to be molded, the electromagnetic shielding molded film of the present invention preferably has an adhesive layer on the outermost layer on the side of Layer A. By using such an electromagnetic shielding molded film, it becomes easy to attach the electromagnetic shielding molded film with the adhesive layer facing the body to be molded.

[0074] As a process for attaching the electromagnetic wave shielding molded film to a molded body, a known thermoforming method that can attach the electromagnetic wave shielding molded film to a molded body having a three-dimensional shape, such as vacuum forming, pressure forming, and vacuum pressure forming, is preferably used.

[0075] In the step of peeling off the base film, the electromagnetic wave shielding molded film is attached to the object to be molded, and then the base film is peeled off to obtain a molded object having the object to be molded and Layer A. Furthermore, in the electromagnetic wave shielding molded film of the present invention, the base film can be easily peeled off by setting the peel strength between Layer A and the base film to 0.005 N / 10 mm or more and 5 N / 10 mm or less. [Example]

[0076] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to these examples.

[0077] The measurement and evaluation methods used in the present examples are as follows.

[0078] (1) Thickness of Layer A The thickness (μm) of Layer A was determined by taking a cross-sectional photograph of the electromagnetic wave shielding molded film at a magnification of 100x using a metallurgical microscope "Leica" (registered trademark) DMLM manufactured by Leica Microsystems, and measuring any five points on the obtained photograph and calculating the average value of the obtained values.

[0079] (2) Average particle size The electromagnetic wave shielding molded film was cut perpendicular to its thickness using a manual rotary microtome (Leica Microsystems' HistoCore BIOCUT® R) to obtain a cross section of the electromagnetic wave shielding molded film. The cross section of layer A was observed using a scanning electron microscope (FEI's XL30 SFEG) at an acceleration voltage of 20 kV and a magnification of 100,000 times. The particle size distribution of the particles present in layer A was calculated from the cross-sectional photograph using image analysis software (Nippon Rover Co., Ltd.'s Image-Pro Plus). Specifically, the diameters (area-equivalent diameters) of 200 or more particles randomly selected from the cross-sectional photograph were measured, and a number-based particle size distribution was obtained by plotting the particle diameter on the horizontal axis and the particle abundance ratio on the vertical axis. In the number-based particle size distribution, the particle diameters on the horizontal axis are classified in 10 nm intervals starting from 0 nm, and the abundance ratio of particles on the vertical axis is expressed by the formula "abundance ratio = total number of detected particles with the corresponding particle diameter / total number of all detected particles." From the particle abundance ratio chart obtained above, the average particle diameter of the peak top showing the maximum was taken as the average particle diameter. If there are multiple peak tops, the peak with the largest vertical axis among the peak tops was taken as the average particle diameter.

[0080] (3) Processability when applying Layer A When the coating composition for forming Layer A was applied to the substrate film, the processability of the film was visually observed and evaluated according to the following criteria. A: No change in the Layer A / substrate film laminate after coating and drying of Layer A. Good results. B: After coating and drying Layer A, there is waviness in the Layer A / substrate film laminate, or there is a crack in part of Layer A. This does not pose a problem in practical use. C: There is a tear in the Layer A / substrate film laminate after coating and drying of Layer A. Or, particles slide off from Layer A. Not suitable for practical use.

[0081] (4) Structure of the electromagnetic wave shielding molded film Layer A and the adhesive layer were applied to the base film in this order and dried, resulting in the following structure of the molded film for electromagnetic wave shielding. A: adhesive layer / layer A / substrate film. B: adhesive layer / substrate film / layer A.

[0082] (5) Formability of Electromagnetic Wave Shielding Film The electromagnetic wave shielding film was attached to the molded body using vacuum and compressed air molding, and the resulting structure of molded body / adhesive layer / Layer A / base film or molded body / adhesive layer / base film / Layer A was visually observed and evaluated according to the following criteria. A: Layer A and the base film conform to the molded body. Good results. B: Layer A and the base film conform to the molded body, but cracks are observed in parts of Layer A or the base film. No practical problems. C: Layer A and the base film do not conform to the molded body, or tears are observed in Layer A or the base film. Not suitable for practical use.

[0083] (6) Surface resistance of layer A The surface resistance of Layer A after coating and drying was measured using a low resistivity meter (Mitsubishi Chemical Analytech's "Loresta" (registered trademark) AX MCP-T370, TFP probe). The evaluation criteria are as follows: A: 1.0 x 10 0 Ω / □ or less is a good result. B: 1.0 x 10 0 Ω / □ or greater than 1.0×10 1 Ω / □ or less, no practical problems. C:1.0×10 1 Larger than Ω / □ and not practical.

[0084] (7) Electromagnetic wave shielding effect at a frequency of 1 GHz The electromagnetic wave shielding molded film was cut into a 120mm x 120mm sample and measured using the KEC method (electric field).The electromagnetic wave shielding effectiveness (dB) at a frequency of 1GHz was measured using a spectrum analyzer, and the result was taken as the electromagnetic wave shielding effectiveness at a frequency of 1GHz.The higher the electromagnetic wave shielding effectiveness, the better the electromagnetic wave shielding properties.

[0085] (8) Electromagnetic wave shielding effect at a frequency of 1 GHz when stretched 1.41 times vertically and 1.41 times horizontally The electromagnetic wave shielding molded film was cut into 120mm x 120mm pieces and subjected to simultaneous biaxial stretching of 1.41 times lengthwise and 1.41 times widthwise using a Bruckner KARO 5.0 lab stretcher to produce samples. Measurements were then carried out using the KEC method (electric field), and the electromagnetic wave shielding effectiveness (dB) at a frequency of 1 GHz was measured using a spectrum analyzer, and the results obtained were taken as the electromagnetic wave shielding effectiveness at a frequency of 1 GHz. A higher electromagnetic wave shielding effectiveness indicates better electromagnetic wave shielding properties.

[0086] The materials used are as follows:

[0087] (Cyclic olefin resin) "TOPAS" (registered trademark) 7010F-600 manufactured by Polyplastics Co., Ltd.

[0088] (Polyethylene resin) "Evolue" (registered trademark) SP2540 manufactured by Prime Polymer Co., Ltd.

[0089] (Particle A) Silver particles (DOWA Electronics Co., Ltd., Ag-2-1C, average particle size 0.8 μm, spherical).

[0090] (Particle B) Silver particles (Fukuda Metal Foil and Powder Co., Ltd., AgG-204B, average particle size 1.8 μm, kidney-shaped).

[0091] (Particle C) Silver particles (AGC-201Z, average particle size 4 μm, flake shape, manufactured by Fukuda Metal Foil and Powder Co., Ltd.).

[0092] (Urethane resin A) Urethane resin containing a polyester component as a copolymer component (manufactured by Toyobo Co., Ltd., "Vylon" (registered trademark) 200, glass transition temperature 67°C).

[0093] (Urethane resin B) Urethane resin containing acrylic component as a copolymer component (manufactured by Taisei Fine Chemical Co., Ltd., 8UA-301, glass transition temperature 60°C).

[0094] (acrylic resin) Acrylic resin (Taisei Fine Chemical Co., Ltd., 1BR-305, glass transition temperature 90°C).

[0095] (insulating particles) Silica particles (manufactured by Nippon Aerosil Co., Ltd., "AEROSIL" (registered trademark) R202, average particle size 0.012 μm).

[0096] [Example 1] <Preparation of base film> The raw materials for obtaining the base film were prepared using the compositions shown in Table 1 and fed into a single-screw extruder (feed temperature 230°C), extruded from a T-die onto a metal shaping roll in the form of a sheet, and nipped with a rubber shaping roll to produce a base film with a thickness of 100 μm.

[0097] <Preparation of Coating Composition for Layer A> The raw materials for obtaining Layer A were prepared as shown in Table 1, dispersed or dissolved in an organic solvent, and kneaded in a three-roll mill to obtain a coating composition for Layer A.

[0098] <Production of molding film for electromagnetic wave shielding> The coating composition for Layer A was applied to the surface of the metal shaping roll of the substrate film by wet coating (bar coating) and dried to laminate Layer A with a thickness of 15 μm.

[0099] Furthermore, a coating composition for the adhesive layer (polyester-based hot melt adhesive GM-3 manufactured by Jujo Chemical Co., Ltd.) was applied onto the above-mentioned layer A by a wet coating method (bar coating method), dried, and cured to laminate an adhesive layer with a thickness of 10 μm, thereby obtaining a molded film for electromagnetic wave shielding having configuration A.

[0100] <Production of molded body> The above-mentioned electromagnetic wave shielding molded film was heated to 120°C using a far-infrared heater at 400°C, and then vacuum-pressure molded (pressure 0.2 MPa) was performed along with an ABS resin molded body (bottom diameter 150 mm, maximum molding magnification 200%) heated to 60°C, to obtain an ABS resin adherend / adhesive layer / Layer A / base film structure. Only the base film was forcibly peeled off from the obtained structure to obtain a molded body.

[0101] [Examples 2 to 10, Comparative Examples 1 to 5] An electromagnetic wave shielding molded film was produced in the same manner as in Example 1, except that the particles, urethane resin, acrylic resin, insulating particles, crosslinking agent, cyclic olefin resin, polyethylene resin, and electromagnetic wave shielding molded film were configured as shown in Table 1.

[0102] In Example 10, after laminating Layer A, a 10 μm thick adhesive layer was laminated on the base layer, not on Layer A, using the same method as above to obtain an electromagnetic wave shielding molded film having Structure B.

[0103] [Table 1] [Industrial Applicability]

[0104] By using the electromagnetic wave shielding molded film and molded body manufacturing method of the present invention, electromagnetic wave shielding properties can be imparted to molded bodies in various molding methods such as vacuum molding, pressure molding, and vacuum / pressure molding. Therefore, the electromagnetic wave shielding molded film and molded body manufacturing method of the present invention can be suitably used to impart electromagnetic wave shielding properties to molded bodies such as mobile phones, electrical appliances, and automobile parts.

Claims

1. a urethane resin that is a polyester resin and / or a urethane resin containing a polyester component as a copolymer component; a surface resistivity of Layer A that is 1.0 x 10 Ω / □ or less; and a surface resistivity of Layer A that is 1.0 x 10 Ω / □ or less. The insulating particles are selected from the group consisting of gold, silver, copper, nickel, chromium, palladium, indium, aluminum, zinc, and platinum; a plated metal powder of any of these metals; a metal powder of an alloy of any of these metals; and an inorganic powder coated with any of these metals. The insulating particles have an average particle diameter of 0.1 μm or more and 1.5 μm or less and are shaped like a sphere, a sphere, an ellipsoid, an ovoid, or a kidney. The insulating particles have an average particle diameter of 0.01 μm or more and 0.1 μm or less. The urethane resin is a polyester resin and / or a urethane resin containing a polyester component as a copolymer component. The surface resistivity of Layer A is 1.0 x 10 Ω / □ or less. The insulating particles are silica or alumina particles.

2. 2. The electromagnetic wave shielding molded film according to claim 1, wherein the electromagnetic wave shielding effect is 40 dB or more when measured using the KEC method (electric field) for electromagnetic waves of a frequency of 1 GHz when the layer A is stretched to 1.41 times its length and 1.41 times its width.

3. The electromagnetic wave shielding molded film according to claim 1 or 2, comprising the layer A and a substrate film.

4. 4. The electromagnetic wave shielding molded film according to claim 3, wherein the base film contains 50% by mass or more and 99% by mass or less of a cyclic olefin resin relative to 100% by mass of the entire base film.

5. 5. The electromagnetic wave shielding molded film according to claim 3, comprising an adhesive layer, the layer A, and the base film in this order, the adhesive layer being the outermost layer.

6. A method for producing a molded body, comprising a step of attaching the electromagnetic wave shielding molded film according to any one of claims 3 to 5 to a body to be molded.

7. A method for producing a molded body, comprising the steps of: attaching the electromagnetic wave shielding molded film according to any one of claims 3 to 5 to a molded body; and peeling off the base film, in this order.

8. 6. A method for producing an electromagnetic wave shielding molded film according to any one of claims 3 to 5, comprising the steps of applying Layer A and an adhesive layer, in this order, to at least one surface of the base film by dip coating, roller coating, wire bar coating, gravure coating, screen printing, comma coating, or die coating, and then subjecting the base film coated with Layer A and the adhesive layer to a heat treatment.

Images