JP2005191443A - Lamination for anti-magnetic wave shield - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamination for an anti-magnetic wave shield which secures the flatness of a base material and is highly reliable. <P>SOLUTION: The lamination for the anti-magnetic wave shield is formed by laminating a transparent base material with a conductive metal foil via an adhesive layer. The adhesive layer contains fine air bubbles (having a diameter of 10 μm or more to 100 μm or less) at a distribution density of 3 bubbles/cm<SP>2</SP>or less, and, preferably, contains a radiation curing resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is for electromagnetic wave shielding for producing an electromagnetic wave shielding transparent laminate used for displays such as plasma display panel (PDP), electroluminescence (EL), cathode ray tube (CRT) and the like. It relates to a laminate.

  In recent years, there has been a remarkable advance in sophistication of society. One of the indispensable items to achieve these is a display. Not only TV but also word processors, personal computers, analyzers, game machines, automobile monitors, mobile phones and so on are widely used. In addition, there is a remarkable increase in size and weight.

  On the other hand, electromagnetic waves radiated from electric and electronic electric devices are becoming a big social problem. There is a risk of noise or malfunction in surrounding equipment due to electromagnetic waves. Since computers are frequently used to increase the number of electronic and electrical devices themselves and control each device, failures are likely to occur, which may lead to serious accidents. In addition, the danger of health problems to the human body has been pointed out. In Europe and the United States, laws and regulations are already in place, and in Japan there are also self-regulations by manufacturer organizations. As a method for shielding (shielding) electromagnetic waves, a method such as making the device casing itself a metal body or a high conductor, inserting a metal plate between the circuit board and the circuit board, or winding a metal foil around the cable, etc. There is.

  The display also needs to shield the electromagnetic wave generated from the front surface. However, the electromagnetic wave radiated from the display surface satisfies the most important “seeing” function of the display by using the method described above. It will disappear. Therefore, an electromagnetic shielding film is installed in order to shield electromagnetic waves from the display surface.

  Since the electromagnetic wave shielding film is installed on the display surface, both high transparency and electromagnetic wave shielding properties are required. In general, it comprises an antireflection layer on the surface, a hard transparent substrate (glass, acrylic plate, etc.) for holding in the middle, and an electromagnetic wave shielding layer.

  Electromagnetic shielding layers include thin metal films formed directly on a hard transparent substrate by vacuum deposition, metal-plated fibers, and metal foils etched, etc. An electromagnetic shielding layer produced by etching a metal foil is judged to be optimal as a method satisfying the properties at a high level. In particular, as disclosed in Patent Document 1, an electromagnetic wave in which a transparent plastic film and a conductive material are bonded via an adhesive, and a geometric figure (simply a mesh shape) is formed on the conductive material by a chemical etching process. It has been found that the method of arranging the shield film on the front surface of the display provides the best characteristics.

  This manufacturing method and material are based on the manufacturing method of a flexible printed wiring board, and are an established method as equipment and method. However, the etched metal foil cannot be handled as a single unit. Therefore, the metal foil is usually bonded in advance using a support such as a film and an adhesive as a base material, and only the metal foil is used with a chemical solution. Etching process.

JP-A-10-41682

  However, the electromagnetic shielding film used for CRT, PDP use, particularly PDP use is not only very large compared to a wiring board including a general-purpose flexible printed circuit board, but also to ensure light transmission and display quality. In addition to using highly transparent materials, it is necessary to form very fine fine lines on the entire surface without defects in patterning the electromagnetic wave shield layer, which does not improve the yield in the manufacturing process and reduces costs. It has become. Of course, since the screen should not be distorted, the electromagnetic wave shielding layer is also required to have high flatness.

  As a factor affecting both the yield improvement and the securing of flatness, there is the quality of the base material used for processing. This base material is generally manufactured by continuously laminating a metal foil such as copper foil and a transparent plastic film such as polyethylene terephthalate (PET) using an adhesive by a hot roll laminating method. . The adhesive used here has high transparency, and in general, an acrylic type, an epoxy type, a polyester type, and a combination thereof are often used. Transparency is a characteristic inherent in adhesives, and if selected, there is no problem, but it is necessary to meet the following requirements.

The transparent plastic film used as the substrate generally has low heat resistance, and it is preferable that the temperature at the time of bonding with the copper foil is as low as possible. In view of price, transparency, and surface smoothness, PET film is the most powerful material. However, in order to use this film, it is necessary to bond at a temperature of 120 ° C. or lower. Above this temperature, the film itself is deformed due to the influence of heat and pressure, and the smoothness of the substrate is not ensured. In order to ensure the above-mentioned quality, the lamination temperature is ideally room temperature.
In the etching process of the metal foil, there is a high temperature treatment process of acid and alkali, and it is necessary to withstand it.

More specifically, the liquid used for etching the metal foil is a strong acid and has a liquid temperature of about 40 ° C. The etching resist used is removed with a strong alkaline solution at a temperature of about 40 ° C. When the chemical resistance of the adhesive is low, discoloration or floating occurs during the processing of this etching step, surface alteration occurs, and transparency is lost.
In addition, the obtained base material requires long-term reliability, and this depends on the final product configuration, but is generally 80 ° C. × 1000 hours. It is evaluated by a treatment such as a treatment at 60 ° C. × 95% × 1000 hours. There should be no visible alteration such as discoloration or blistering when processed under these conditions.

  In a conventional method for producing an electromagnetic wave shielding material, a thermoplastic resin is continuously applied as an adhesive on a transparent plastic film, and is thermally laminated with a metal foil such as a copper foil. In this thermal lamination, only the adhesive is softened by heat. As a result, in order to ensure the adhesion between the metal foil and the adhesive, it is necessary to sufficiently soften the adhesive. This adhesion force is considered to be at least about 100 gf / cm in consideration of circuit peeling of the metal foil during processing and product reliability.

  In the case of thermal lamination, the heating time at the time of bonding is instantaneous. In order to achieve both sufficient softening of the adhesive and a short heating time, the temperature of the hot roll during production needs to be set significantly higher than the Tg of the adhesive, and the pressure must also be set to a large setting.

  Furthermore, in order to satisfy the above-mentioned conditions for electromagnetic shielding film applications, heat resistance, chemical resistance, and reliability are regarded as important. Therefore, the adhesive used mainly contains a high molecular weight material having a relatively high Tg. Is preferred. In such a formulation, the softening temperature of the adhesive increases and the degree of softening decreases. Moreover, in order to embed the softened adhesive on the rough surface of the copper foil, a high pressure is required. However, when pasting together with a high pressure, it is difficult to smoothly laminate a thin metal foil and a transparent plastic with an adhesive softened by heat. At this time, when the transparent plastic with adhesive sags, the pressure is not applied smoothly, and microbubbles (φ10 μm or more and φ100 μm or less) exist in the adhesive at the low pressure portion. If these microbubbles are densely packed, they may be observed with the naked eye.

  As a result, the temperature and pressure at the time of bonding of the copper foil / transparent plastic film are increased, and among the materials, the plastic film having poor heat resistance is deformed, making it difficult to ensure the flatness of the substrate.

The present invention has been made in view of the above problems, and is a laminated body for electromagnetic wave shielding that ensures smoothness and has reliability, and is a laminated body for producing an electromagnetic wave shielding transparent laminated body. , Relating to:
1. In the laminate for an electromagnetic wave shield in which the conductive metal foil is laminated on the transparent substrate via the adhesive layer, the number of microbubbles (φ10 μm to φ100 μm) in the adhesive layer is 3 / cm ² or less. A laminate for electromagnetic wave shielding, characterized in that it is present.
2. Item 2. The laminate for electromagnetic wave shielding according to Item 1, wherein the adhesive layer contains a radiation curable resin.

  The laminate for electromagnetic wave shielding according to the present invention and the electromagnetic shielding transparent laminate produced therefrom have high reliability.

  The transparent substrate in the present invention is preferably a transparent plastic film, and examples of the material include acrylic resin, polycarbonate, polyethylene, polypropylene, and polyester. The transparent plastic film may be a single layer or a multilayer body having two or more layers. Polyester films, particularly PET films are preferred because of transparency, smoothness of the film, ease of handling, price, availability of various thickness products, and the like. The term “transparent” as used herein means that having a visible light (400 to 700 nm) average transmittance of 87% or more. Moreover, the presence or absence of coloring will not be ask | required if it prescribes | regulates by the average transmittance | permeability. The thickness is preferably 25 to 250 μm, and more preferably 50 to 150 μm.

As the adhesive in the present invention, a thermoplastic resin, a thermosetting resin, a radiation curable resin, or the like can be used.
As the thermoplastic resin, natural rubber (n = 1.52: n represents a refractive index, the same shall apply hereinafter), polyisoprene (n = 1.521), poly-1,2-butadiene (n = 1.50) , Polyisobutene (n = 1.505 to 1.51), polybutene (n = 1.513), poly-2-heptyl-1,3-butadiene (n = 1.50), poly-2-t-butyl- (Di) enes such as 1,3-butadiene (n = 1.506) and poly-1,3-butadiene (n = 1.515), polyoxyethylene (n = 1.456), polyoxypropylene ( n = 1.450), polyethers such as polyvinyl ethyl ether (n = 1.454), polyvinyl hexyl ether (n = 1.659), polyvinyl butyl ether (n = 1.456), polyvinyl acetate (n = 1 . 67), polyesters such as polyvinyl propionate (n = 1.467), polyvinyl butyral resin (n = 1.52), EVA resin (n = 1.48-1.49), polyvinyl acetate resin (n = 1.5), polyurethane (n = 1.5 to 1.6), polyester polyurethane (n == 1.5 to 1.6), ethyl cellulose (n = 1.479), polyvinyl chloride (n = 1) .54 to 1.55), polyacrylonitrile (n = 1.52), polymethacrylonitrile (n = 1.52), polysulfone (n = 1.633), polysulfide (n = 1.6), phenoxy resin (N = 1.5 to 1.6), polyethyl acrylate (n = 1.469), polybutyl acrylate (n = 1.466), poly-2-ethylhexyl acrylate (n = 1.463) , Poly-t-butyl acrylate (n = 1.464), poly-3-ethoxypropyl acrylate (n = 1.465), polyoxycarbonyltetramethacrylate (n = 1.465), polymethyl acrylate (n = 1) .472-1.480), polyisopropyl methacrylate (n = 1.473), polydodecyl methacrylate (n = 1.474), polytetradecyl methacrylate (n = 1.475), poly-n-propyl methacrylate (n = 1.484), poly-3,3,5-trimethylcyclohexyl methacrylate (n = 1.484), polyethyl methacrylate (n = 1.485), poly-2-nitro-2-methylpropyl methacrylate (n = 1.487), poly-1,1-diethylpropyl methacrylate (n = 1.4) 89) and poly (meth) acrylic acid esters such as polymethyl methacrylate (n = 1.490) can be used. Two or more kinds of these acrylic polymers may be copolymerized as required, or two or more kinds may be blended and used.

As the thermosetting resin, epoxy acrylate (n = 1.48 to 1.60), urethane acrylate (n = 1.5 to 1.6), polyether acrylate (n = 1.48 to 1.49), Polyester acrylate (n = 1.48 to 1.54) or the like can also be used. In particular, urethane acrylate, epoxy acrylate, and polyether acrylate are excellent from the viewpoint of adhesiveness. As the epoxy acrylate, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, allyl alcohol diglycidyl ether, resorcinol (Meth) acrylic such as diglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol tetraglycidyl ether An acid adduct is mentioned. A polymer which reacts like an epoxy acrylate or originally has a hydroxyl group in the molecule is effective for improving the adhesion. These thermosetting resins can be used in combination of two or more as required.
It is preferable that a curing agent is used in combination with the thermosetting resin. Such curing agents include amines such as triethylenetetramine, xylenediamine, N-aminotetramine, diaminodiphenylmethane, phthalic anhydride, maleic anhydride, dodecyl succinic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, etc. Acid anhydride, diaminodiphenylsulfone, tris (dimethylaminomethyl) phenol, polyamide resin, dicyandiamide, ethylmethylimidazole, and the like can be used. These may be used alone or in combination of two or more. The addition amount of these curing agents is preferably 0.1 to 50 parts by weight, particularly 1 to 30 parts by weight, based on 100 parts by weight of the reactive resin.
The thermosetting resin can be used in combination with the thermoplastic resin.

  The refractive index of the adhesive layer used in the present invention is preferably in the range of 1.35 to 1.70. This is because when the refractive index of the plastic support and the resin layer used in the present invention is different, the visible light transmittance is lowered. When the refractive index is 1.35 to 1.70, the visible light transmittance is lowered. The refractive index of the above-mentioned polymer which is small and good is within this range.

The radiation curable resin used in the present invention is transparent, requires chemical resistance in the etching process of the metal foil, and is required to withstand a reliability test after commercialization. Examples of the resin curing system include a radical polymerization system and a cationic polymerization system. Examples of the radiation curable resin include materials in which an acrylic resin, an epoxy resin, a polyester resin, a urethane resin, or the like is used as a base polymer and a radically polymerizable or cationically polymerizable functional group is added to each. As radically polymerizable functional groups, there are carbon-carbon double bonds such as acryl group (acryloyl group), methacryl group (methacryloyl group), vinyl group, allyl group, etc., and highly reactive acrylic group (acryloyl group) is suitable. Used for. As the cationically polymerizable functional group, an epoxy group (glycidyl ether group, glycidylamino group) is representative, and a highly reactive alicyclic epoxy group is preferably used. Specific materials include acrylic urethane, epoxy (meth) acrylate, epoxy-modified polybutadiene, epoxy-modified polyester, polybutadiene (meth) acrylate, and acrylic-modified polyester. Moreover, the composition which added the photosensitive agent and the sensitizer to these as needed is used. When the radiation is ultraviolet rays, known materials such as benzophenone, anthraquinone, benzoin, sulfonium salt, diazonium salt, onium salt, halonium salt are used as a photosensitizer or photoinitiator added during ultraviolet curing. can do.
The radiation curable resin can be used in combination with the thermoplastic resin.

  The radiation referred to in the present invention refers to ionizing radiation such as ultraviolet rays and α rays, β rays, γ rays, neutron rays, and accelerated electron rays. In the case of ultraviolet rays, the wavelength range is about 180 to 460 nm, and suitable sources include metal halide lamps, low to ultra high pressure mercury lamps, mercury arcs, and the like. In the case of ionizing radiation, the dose can be used in the range of 0.1 to 50 Mrad. However, considering the cost of capital investment and safety management, ultraviolet curing is most preferable.

  In the adhesive layer in the present invention, an infrared absorber, an ultraviolet absorber, a filler, a tackifier dispersant, a thixotropic agent, an antifoaming agent, a leveling agent, a diluent, a plasticizer, and an oxidation agent, if necessary. You may mix | blend additives, such as an inhibitor, a metal deactivator, a coupling agent, and a filler. These resins or resin compositions can be dissolved in an ordinary general-purpose solvent or used without a solvent.

The softening temperature of the resin for the adhesive layer and, if necessary, the resin composition containing the above additives is preferably 200 ° C. or less, and more preferably 150 ° C. or less from the viewpoint of handleability. 80 to 120 ° C. is most preferable from the viewpoint of manufacturing a structure in which a plastic support, a resin layer, and a conductive metal foil are sequentially laminated, and workability in the case of covering from a geometric figure. The thermosetting resin or radiation curable resin is also preferably softened or fluidized at such a temperature before curing. The softening temperature is a temperature at which the viscosity becomes 10 ¹² poises or less, and normally, the flow is recognized within a time of about 1 to 10 seconds at that temperature.
The adhesive layer preferably has an adhesive function by flowing and exhibiting fluidity by heating or pressurization (for example, heating at 200 ° C. or lower or pressurization at 1 Kgf / cm ² or higher).

  The adhesive layer contains the radiation curable resin, and is therefore preferably a layer (photosensitive resin layer) that is cured by irradiation with radiation. As described below, the photosensitive resin layer is preferably composed of a transparent substrate, an adhesive layer, and a conductive metal foil that are sequentially laminated before or after forming a geometric figure drawn with a conductive metal. Further, it can be cured by irradiation with radiation. After that, the photosensitive resin layer may be cured by irradiating with radiation after forming an electromagnetic wave shielding body or display which is an adherend of the electromagnetic wave shielding transparent laminate. It is also possible to slightly advance the degree of curing in advance by irradiation before adhering to the adherend. In this case, the melt viscosity of the resin layer after progressing the degree of curing is a numerical value measured with a rotational viscometer at 200 ° C. and is preferably 10000 poise or less. This is because the fluidity of the adhesive layer is ensured in order to enable processing such as adhesion by pasting even after the degree of curing of the adhesive layer is advanced. Any adhesive layer may be used as long as the adhesive layer can exhibit fluidity and adhesiveness even in a completely cured state.

  The resin of the adhesive layer preferably has a glass transition temperature (Tg) of 40 ° C. or higher after being cured or solidified. The reason is to prevent coloring in the etching process. This is because if this layer has a low Tg, it may be softened by the high-temperature treatment liquid exposed in the following etching step, and the color of the liquid may adhere. The processing solution temperature in a general etching process is about 40 ° C., and if the Tg of the adhesive layer after curing is about 40 ° C., there is no fear of coloring. Also, by lowering the etching solution temperature in the process, the softening of the adhesive layer is suppressed and the color becomes difficult to adhere, but it is necessary to reduce the process speed as well, so that the productivity is inferior.

  In the laminate for electromagnetic wave shielding in the present invention, an adhesive is applied on a transparent base material, a conductive metal foil, or both, and then the transparent base material and the conductive metal foil are bonded by a laminating method with the adhesive interposed therebetween. It can be manufactured by stacking together. At that time, a high temperature and a large pressure are not required by using an adhesive containing a radiation-curable resin that is soft at room temperature. Therefore, since deformation of the base material can be suppressed, it is possible to stably manufacture a base material having a three-layer structure smoothly. As a result, pressure is applied smoothly to the adhesive containing the radiation curable resin applied on the metal foil or the transparent plastic film and the other side to be bonded, so that microbubbles (φ10 μm or more in the adhesive) It is easy to adjust so that (φ100 μm or less) does not occur.

  The method for applying the adhesive is not particularly limited, but a continuous application method is preferable from the viewpoint of productivity. Examples of the system include a roll coater, a die coater, a gravure coater, a doctor blade, and the like, but are not particularly limited. The resin contained in the adhesive of the present invention may be either a solventless type or a solvent dilution type. In general, the solvent-free type does not require a solvent drying furnace, so that it can be manufactured in a relatively small-scale facility and is more useful. In addition, the solvent dilution type needs attention because the transparent base material or the conductive metal foil may be deformed by heat at the time of solvent drying.

  When ultraviolet rays are selected as the radiation, there is a concern about deformation of the transparent base material due to radiant heat from the ultraviolet lamp at the time of ultraviolet irradiation, so the lamp and the transparent base material are separated and a transparent base is introduced by introducing a cooling device or the like. It is preferable to keep the material at 40 ° C. or lower. In order to suppress the deformation of the transparent substrate, it is important not to apply a temperature as much as possible during the production of the substrate.

  The thickness of the adhesive layer after curing is preferably thin because the production speed can be improved. However, if the thickness is too thin, the probability of occurrence of a coating film defect increases. Generally about 0.5-50 micrometers is preferable. More preferably, it is 5-25 micrometers.

  The adhesive application step is preferably performed continuously from the viewpoint of productivity. In this case, the transparent base material and the conductive metal foil are sent out from another roll, and are applied, laminated, and UV cured. It is preferable to wind in a roll shape.

  If the polyester film which is a preferable material in the present invention is formed while stretching in two directions in the plane at the time of producing the film, the stress existing inside is released when subjected to high temperature treatment, and there is a possibility that deformation such as shrinkage or distortion may occur. is there.

In order to ensure reliability in the final product, it is preferable to use a relatively high Tg (40 ° C. or higher) thermoplastic resin as an adhesive in the electromagnetic shielding laminate.
If an attempt is made to bond a transparent base material (particularly preferably a polyester film) to which a conductive metal foil and an adhesive are continuously applied using this resin, the roll surface temperature during thermal lamination is 130 ° C. or higher. Necessary, deformation of the transparent substrate occurs, causing distortion and wrinkling, and lowering the production yield. On the other hand, by using a radiation curable resin as an adhesive, it is possible to manufacture at a low temperature and low pressure, and it is possible to manufacture a high-quality base material with almost no deformation, and further increase the production speed and man-hours. Reduction in production cost can be suppressed. When a radiation curable resin is used as an adhesive, it is possible to produce a high-quality electromagnetic shielding laminate with almost no deformation, and it is possible to reduce production costs by improving production speed or reducing man-hours.

  The conductive metal foil is not limited as long as it is a metal foil made of copper, nickel, aluminum, or the like, but copper foil is considered optimal in view of price, fine wire workability, and productivity. Moreover, although the thickness of copper foil does not have limitation in particular, the thickness of 9-20 micrometers is preferable.

By processing the conductive metal foil of the electromagnetic wave shielding laminate so as to draw a geometric figure, an electromagnetic wave shielding transparent laminate can be produced.
In the above, as a method used when drawing a geometric figure on a conductive metal foil, a microlithographic method that is effective in terms of the accuracy of processing of a circuit corresponding to the geometric figure and the efficiency of processing of the circuit is used. Can do. At this time, there is a pattern forming process using a mask material for etching such as photoresist, and this includes a method including a photoresist layer forming process, an exposure process and a pattern forming process by etching, and an ink that is a mask material for etching. A printing method using a resist (for example, a letterpress reverse offset printing method, a screen printing method, a planographic offset printing method, an intaglio offset printing method, etc.) can be used. The photolithographic method is excellent because it is excellent in line formation with high accuracy of 50 μm or less. The relief reversal offset method is a method in which an ink resist is filled in a concave portion of a plate, the ink resist is once transferred to a blanket, and then printed on a conductive metal foil.

  Examples of the microlithographic method include a photolithographic method, an X-ray lithographic method, an electron beam lithographic method, and an ion beam lithographic method. Among these, the photolithographic method is the most efficient in terms of its simplicity and mass productivity. Of these, the photolithographic method using the chemical etching method is most preferable from the viewpoint of its simplicity, economy, and circuit processing accuracy. In the photolithographic method, in addition to the chemical etching method using an etchant solution, a conductive circuit is formed on the resist pattern by electroless plating or electroplating on the resist pattern, or conductive by electroless plating or electroplating. It is also possible to combine the method of forming a circuit with the chemical etching method.

  When the number of microbubbles present in the adhesive layer exceeds 3 in the laminate for electromagnetic wave shielding in the present invention, when the electromagnetic wave shielding transparent laminate is used, not only the transparency is impaired, but also 40 to 60 ° C. Swelling may occur at a relatively high temperature. In this case, transparency is further lowered, and smoothness and reliability are impaired.

A copper foil for printed wiring board having a thickness of 12 μm (trade name: PBR-10A, manufactured by Nippon Electrolytic Co., Ltd., hereinafter abbreviated as “copper foil 1”) is used as the conductive metal foil, and a polyester film having a thickness of 125 μm is used as the transparent plastic film. The product (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd., hereinafter abbreviated as film A) was used.
First, an ultraviolet curable resin (1) (trade name: Adekaoptomer KRX-400, manufactured by Asahi Denka Co., Ltd., radical polymerization solventless type) is applied to film A as an adhesive, and then copper foil 1 is ultraviolet cured. Lamination (roll surface temperature 25 ° C.) was performed on the surface of the mold resin (1). Immediately thereafter, curing was performed by ultraviolet irradiation (ultra-high pressure mercury lamp, 1000 mJ / cm ² ) to produce a laminate having a three-layer structure. The thickness of the ultraviolet curable resin was 10 μm.

  These were continuously applied, laminated and cured. An outline of a manufacturing apparatus for this purpose is shown in FIG. The copper foil 1 and the transparent plastic film 2 are unwound from the roll 3 and the roll 4, respectively, and the transparent plastic film 2 is coated with an adhesive containing a radiation curable resin by a coating device. The transparent plastic film 2 coated with the metal foil 1 and the adhesive is laminated by a laminating roll 6, and the obtained laminate is irradiated with radiation by a radiation radiating device 7 to cure the adhesive, and the laminate is wound up. Take up by 8.

  The speed at which the laminate was produced was fixed at 5 m / min in consideration of productivity (the same applies to the following examples).

  A laminate having a three-layer structure was prepared in the same manner as in Example 1 except that the ultraviolet curable resin (1) was applied as an adhesive to the copper foil 1 and then the film A was laminated on the surface of the ultraviolet curable resin (1). Produced.

A 12 μm thick copper foil for printed wiring boards (trade name: SQ-VLP, manufactured by Mitsui Mining & Smelting Co., Ltd., hereinafter abbreviated as “copper foil 2”) is used as the conductive metal foil, and the polyester film has a thickness of 125 μm. (Product: O3PFW, manufactured by Teijin DuPont Films, Ltd., hereinafter abbreviated as Film B) was used.
First, UV curable resin (2) (trade name: MGS-105, manufactured by Nippon Kayaku Co., Ltd., radical polymerization solventless type) is applied as an adhesive to film B, and then copper foil 2 is applied to UV curable resin. (2) Laminated on the surface (roll surface temperature 25 ° C.). Immediately thereafter, curing was performed by ultraviolet irradiation (ultra-high pressure mercury lamp, 1000 mJ / cm ² ) to produce a laminate having a three-layer structure. The thickness of the ultraviolet curable resin was 10 μm. The outline of the manufacturing apparatus is as shown in FIG.

  UV curable resin (2) (trade name: MGS-105, manufactured by Nippon Kayaku Co., Ltd., radical polymerization solventless type) UV curable resin (3) (trade name: FOP-1800, Nippon Kayaku) A laminate having a three-layer structure was produced according to Example 3 except that Yakuhin Co., Ltd. (radical polymerization solventless type) was used.

(Comparative Example 1)
A copper foil 12 μm thick product for printed wiring boards (trade name: PBY-10A, manufactured by Nippon Electrolytic Co., Ltd., hereinafter abbreviated as “copper foil 1”) is used as the metal foil, and a polyester plastic 125 μm thick product ( Product: Emblet S, manufactured by Unitika Ltd., hereinafter abbreviated as film C).
First, a thermoplastic resin (1) (trade name: Byron UR-1400, manufactured by Toyobo Co., Ltd., polyester resin) is continuously applied on the film C as an adhesive, and dried to obtain a film α with a thermoplastic resin. Produced. The drying conditions were 120 ° C. × 1 minute, and the thickness of the adhesive layer after drying was 20 μm. The thermoplastic resin (1) has a Tg of 83 ° C.
Next, the film α with the thermoplastic resin and the copper foil were continuously roll-laminated. In addition, it laminated by the laminating machine which has a preheating apparatus before lamination. In this preheating device, when the object to be laminated suddenly comes into contact with the heating / pressurizing roll, it deforms due to a rapid temperature change and gets wrinkled, so that the object to be laminated is heated in advance to moderate the temperature change. It is an indispensable facility when processing films, thin metals, and the like.
The speed during lamination was fixed at 2 m / min. At other speeds, the flow of the thermoplastic resin was insufficient, and it was difficult to produce a substrate having a three-layer structure. Lamination conditions were 115 to 130 ° C., a laminate roll surface temperature of 150 ° C., and a pressure of 1.0 MPa.

(Comparative Example 2)
The same metal foil and film as those in Comparative Example 1 were used. Thermoplastic resin (2) (trade name: Dianal BR-64, manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin) was used. The Tg of this resin is 55 ° C.
First, a thermoplastic resin (2) as an adhesive was continuously applied onto the film C and dried to prepare a film β with a thermoplastic resin. The drying conditions were 120 ° C. × 1 minute, and the thickness of the adhesive layer after drying was 20 μm. Next, the film β with thermoplastic resin and the copper foil were continuously roll-laminated. The speed during lamination was fixed at 2 m / min. Regarding the laminating conditions, the temperature of an object to be laminated by preheating was 100 to 110 ° C, the surface temperature of the laminating roll was 120 ° C, and the pressure was 0.8 Mpa.

  Table 1 shows examples and comparative examples obtained as described above.

(Test method)
The test method was carried out under the following conditions.
[Micro bubbles]
Using an stereo microscope (× 140), the adhesive layer is observed from the transparent plastic film surface of the produced three-layer laminate.

[Copper foil / resin adhesion]
A line having a width of 0.5 mm is processed by etching the produced copper foil of the three-layer base material.

    Peel between 0.5 mm wide copper and adhesive in the direction of 90 degrees at a speed of 50 mm / min, and measure the peel strength.

[Adhesion between transparent plastic film / adhesive layer]
A cut is made into a width of 10 mm with a cutter on the transparent plastic film side of the laminate having the three-layer structure. The transparent plastic film and the adhesive layer are peeled in the horizontal direction (T peel) at a speed of 50 mm / min, and the peel strength is measured.

  The test results obtained are shown in Table 2.

The schematic diagram of an example of the substrate manufacture device for carrying out the present invention.

Explanation of symbols

1: Metal foil 2: Transparent plastic film 3: Roll 4: Roll 5: Adhesive application device 6: Laminate roll 7: Radiation emission device 8: Winding device

Claims (2)

In the laminate for an electromagnetic wave shield in which the conductive metal foil is laminated on the transparent substrate via the adhesive layer, the number of microbubbles (φ10 μm to φ100 μm) in the adhesive layer is 3 / cm ² or less. A laminate for electromagnetic wave shielding, characterized in that it is present. The laminate for electromagnetic wave shielding according to claim 1, wherein the adhesive layer contains a radiation curable resin.

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