JP2007227906A - Conductive substrate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive transparent substrate that does not cause Moire phenomena and excels in magnetic field shielding properties in a low frequency region particularly required by a plasma display panel. <P>SOLUTION: This conductive substrate has a random mesh net layer, where micro metallic particle layers are laminated in a random mesh net shape on at least one side of the substrate and plated metallic layers are laminated on the micro metallic particle layers. The thickness of at least one side surface of the plated metallic layer of this conductive substrate is no less than 1.5 μm. The total light transmission rate of the conductive substrate is larger than 65%. Furthermore, the surface resistivity of at least one side surface of the conductive substrate is smaller than 0.5 Ω/SQARE. The foregoing are the main features of this invention. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive substrate that does not cause moire phenomenon, has excellent transparency and electromagnetic wave shielding properties, and particularly has excellent magnetic field shielding properties in a low frequency region that is characteristically required for plasma display panels, and a method for manufacturing the same. It is.

  Conductive substrates are used in various devices as circuit materials, and are used as electromagnetic shielding substrates and solar cell applications.

  The electromagnetic shielding substrate is used for the purpose of suppressing various electromagnetic waves radiated from electronic devices such as home appliances, mobile phones, personal computers, and televisions. Among digital home appliances, which are particularly growing, plasma display panels emit stronger electromagnetic waves than other display panels such as cathode ray tubes and liquid crystals, and there are concerns about the effects on the human body. Since a plasma display observes an image at a relatively close distance and in some cases for a long time, an electromagnetic wave shielding substrate that suppresses these electromagnetic waves is required, and has been intensively studied. Further, it is known that a magnetic field generated by a low frequency region emitted from a display, particularly an electromagnetic wave of 30 MHz or less, adversely affects recording and reproduction of a video tape that is a magnetic recording medium. A video deck, which is a video tape recording / reproducing device, is generally used at a distance close to a display, and therefore a substrate excellent in magnetic field shielding in a low frequency region is required. In plasma display panels that emit stronger electromagnetic waves compared to other display panels, there is a strong demand for substrates having excellent magnetic field shielding properties particularly in this low frequency region.

  As such an electromagnetic wave shielding substrate, a substrate in which a copper foil is laminated in a plastic film shape, and then a copper foil is laminated in a lattice shape by using photolithography and etching techniques is used. Since the grid-like copper foil layer has a regular structure, it has a problem that a moire phenomenon occurs.

  Moiré phenomenon is "a striped pattern that occurs when dots or lines are distributed in a geometrically regular manner", and according to Hiroshige, "the points or lines are distributed in a geometrically regulated manner. Stripe pattern mottles that occur when images are overlapped. This is likely to occur when a halftone print is reproduced using a halftone print as a manuscript. ”In the case of a plasma display, a striped pattern appears on the screen. Will occur. This is because, when a regular pattern such as a grid pattern is provided on the electromagnetic shielding substrate provided on the front surface of the display, it interacts with a regular grid-shaped partition wall that partitions the pixels of each RGB color on the back side of the display. This moire phenomenon occurs. Further, when a regular pattern such as a grid pattern is provided on the electromagnetic wave shield substrate, there is a problem that the moire phenomenon is more likely to occur as the line width of the grid increases.

  On the other hand, as an electromagnetic wave shielding substrate having a different form from the above-mentioned substrate laminated with a grid-like copper foil, an electromagnetic wave shielding substrate in which a mesh is formed using silver fine particles and a plated metal layer is laminated on the mesh is proposed. (Patent Documents 1 to 4).

  However, even with the techniques described in Patent Documents 1 to 4, it has been difficult to eliminate the moire phenomenon and achieve both transparency and magnetic field shielding performance in a low frequency region.

  The technique described in Patent Document 1 is to form a fine network structure such as silver using spray spraying, and the network structure is not regular and may reduce the moire phenomenon. However, since the opening diameter of the mesh by a manufacturing method such as spraying can only be as small as about 50 μm, when the plating metal layer is laminated thickly, most of the opening is blocked and the transparency is poor. Only things could be manufactured. Further, when the transparency is improved, the plating thickness is reduced and the surface specific resistance is inferior, so that it is impossible to achieve both magnetic field shielding and transparency in the low frequency region.

  In the technique described in Patent Document 2, a metal ultrafine catalyst layer made of silver or the like is supported on alumina fine particles, and then kneaded with a binder to make a paste, and an electroless plating metal layer is provided on the printed layer. Technology. However, with this technique, since the line width of the printed layer is a thick grid structure of about 60 μm, moire is likely to occur. In this technology, the silver fine particle content in the printing layer is very low, such as several weight percent or less, and most of the components contained in the printing layer are formed from alumina fine particles and a binder, and the viscosity of the paste becomes high. Therefore, it has been very difficult to reduce the line width of a pattern obtained by printing such a material.

  In the technique described in Patent Document 3, a paste obtained by mixing particles having a particle size larger than 1 μm and a resin component is printed in a regular pattern, and then an electrolytic plating metal layer is provided. However, with this technique, the printed pattern is regular and the line width is as thick as about 20 μm, so that moire is likely to occur. In addition, since particles having a particle size larger than 1 μm are used, there is a problem in that there is a limit to making the print pattern, which is an aggregate, thin.

Patent Document 4 describes a technique in which a silver salt-containing layer is exposed and developed to form a metallic silver network, and then a plated metal layer is provided. However, since this technique creates a mesh pattern created by combining predetermined shapes, the pattern has regularity and the possibility of the occurrence of moire phenomenon. It was. Since this method can easily obtain a relatively thin pattern, it is difficult to see the moire phenomenon when the plating thickness is thin. However, it is not sufficient, and in the low frequency region due to the thin plating thickness. Only inferior magnetic field shielding properties were obtained. Further, when the plating thickness is increased in order to develop magnetic field shielding properties in the low frequency region, the line width becomes thicker due to the plating, so that the moire phenomenon appears strongly.
: JP-A-10-340629 (first page, claims, etc.) : JP-A-11-170420 (first page, claims, etc.) : JP 2000-196286 A (first page, claims, etc.) : JP-A-2004-221564 (first page, claims, etc.)

  The object of the present invention is to eliminate the above-mentioned drawbacks and to be transparent, and not to cause moire phenomenon, which is difficult to solve with the prior art, and particularly to shield magnetic fields in a low frequency region that is characteristically required for plasma display panels. An object of the present invention is to provide a conductive substrate that satisfies the three characteristics of excellent performance.

  The present invention is a conductive substrate having a random network layer in which a metal fine particle layer is laminated in a random network shape on at least one surface of a substrate, and a plated metal layer is laminated on the metal fine particle layer, the electromagnetic wave shield The thickness of the plated metal layer on at least one side of the substrate is 1.5 μm or more, the total light transmittance of the electromagnetic wave shielding substrate is greater than 65%, and the surface specific resistance of at least one side of the electromagnetic wave shielding substrate is 0. The conductive substrate is smaller than 5Ω / □.

  According to the present invention, as described below, it is transparent, does not cause moire phenomenon, and particularly satisfies the three characteristics of being excellent in magnetic field shielding properties in a low frequency region which is characteristically required for a plasma display panel. An electrically conductive substrate can be obtained.

  In the present invention, a metal fine particle layer is laminated in a random network shape, and a plated metal layer is laminated thereon to form a random network layer, so that there is no moire and in a low frequency region, particularly a region of 30 MHz or less. A transparent substrate having excellent magnetic field shielding properties can be obtained.

  The total light transmittance of the conductive substrate in the present invention needs to be larger than 65%, more preferably 70% or more, and further preferably 75% or more. If the total light transmittance is 65% or less, a problem arises in terms of transparency.

  In the present invention, in order to make the total light transmittance of the conductive substrate larger than 65%, it is necessary to make the mesh line of the metal fine particle layer thinner and to enlarge the opening.

  The method for laminating the metal fine particle layer on the substrate is not particularly limited, and a structure in which the metal fine particle layer is connected in a network shape may be formed on at least one surface of the substrate.

  For example, a method of printing a metal fine particle paste or solution in a mesh pattern, a method of applying a metal fine particle paste or solution in a mesh pattern, or after laminating metal fine particles on the entire surface of a substrate, so that the metal particle layer becomes a mesh pattern. A method of physically cutting or chemically etching, digging or embossing a substrate to create a mesh-like groove on at least one side of the substrate in advance, and there are metal fine particles there Various methods such as a method of filling a solution can be selected.

  However, it is difficult to form a random network structure that satisfies the requirements of the present invention by these printing, etching, and groove forming methods. Specifically, since printing has a large line width, transparency may be reduced. Etching and the method of forming a groove tend to provide a straight line, so that the randomness is inferior and moire may appear strongly.

  In addition, in the case of a method in which metal fine particles are laminated on the entire surface of the substrate and then the metal fine particle layer is physically cut so as to form a network or chemically etched, the metal fine particle layer is cut or etched. In the case where the substrate of the opening portion that appears or the surface treatment layer or the adhesive layer is laminated therebetween, the unevenness of the metal fine particles may be transferred to those layers. As a result, the surface roughness of the layer present in the opening is increased, and there may be a case where only the haze is high and the transparency is insufficient. When the haze increases, when the substrate of the present invention is used as a display application, the image of the display observed through the substrate is blurred, and the visibility of the image may be lowered. In the present invention, the haze of the conductive substrate is preferably 20% or less, more preferably 15% or less, and further preferably 10% or less.

  Therefore, instead of the above-described technique for forming printing, etching, and grooves, in the present invention, for example, as described in JP-A-10-340629, a solution for forming a metal fine particle layer is applied to a substrate. Thus, a method of forming a fine particle network using a phenomenon in which fine particles partially gather to form a mesh line, that is, a so-called self-organization phenomenon is preferable. When such a method is used, the mesh is likely to be random, and a substrate having a low haze is easily obtained. That is, it is preferable to use a “self-organizing solution”. Here, the “self-organizing solution” is a solution that spontaneously forms a network structure on a substrate when applied to one surface of the substrate and left to stand. As such a solution for forming the metal fine particle layer, for example, CE103-7 manufactured by Cima NanoTech can be used.

  When forming a network structure using a solution of metal fine particles, for example, printing using a solid solution (metal colloid solution) mainly composed of particles composed of metal fine particles and organic components such as a dispersant. And a method of coating can be suitably used. As a solvent for the metal colloid solution, water and various organic solvents can be used.

  Examples of the method for adjusting the metal fine particles include a chemical method in which metal ions are reduced to metal atoms in a liquid layer to grow into nanoparticles through atomic clusters, or bulk metal is evaporated in an inert gas to form fine particles. A method of trapping the resulting metal with a cold trap, or a method in which a metal thin film obtained by vacuum deposition on a polymer thin film is heated to break the metal thin film, and the metal nanoparticles are dispersed in the polymer in a solid state. A technique or the like can be used.

  As the compound that forms the metal fine particle layer, metal oxide fine particles that are compounds capable of forming metal fine particles, organometallic compounds, or a compound in which two or more of these are mixed are used to finally chemically change to metal fine particles. And a metal fine particle layer may be formed.

  In the present invention, a metal fine particle is prepared by using a compound in which at least one selected from the group consisting of a metal fine particle, a metal oxide fine particle, and an organometallic compound is dispersed or dissolved in a solvent. It is preferable to form a layer. After preparing these solutions, the resin components and other various additives such as antioxidants, heat stabilizers, weathering stabilizers, UV absorbers, organic lubricants, pigments, dyes, organic or inorganic A solution to which fine particles, a filler, an antistatic agent, a nucleating agent and the like are added to such an extent that the properties are not deteriorated can also be suitably used.

  On the other hand, when a compound that can form the above-mentioned metal fine particles is kneaded into the resin component and dispersed in the resin component, the conductivity by organic solvent treatment and acid treatment described later is increased. Since the effect is not sufficiently exhibited and excellent conductivity may not be obtained, it is not preferable. In addition, after dispersing a compound capable of forming metal fine particles in the resin component, the viscosity was adjusted by adding a solvent, or a compound capable of forming metal fine particles was kneaded into the resin component together with the resin component and the solvent. Even if it is a thing, since the effect by the organic solvent process mentioned later and an acid process does not fully express, and the outstanding electroconductivity may not be obtained, it is unpreferable.

  When a solution in which at least one selected from the group consisting of metal fine particles, metal oxide fine particles, and organometallic compounds is dispersed or dissolved in a solvent is used, as described later, a low-concentration acid solution causes The effect of the treatment can be easily obtained, and the conductivity of the metal fine particle layer can be preferably improved. When using a high concentration acid, workability | operativity falls and productivity may deteriorate, and it is unpreferable. When the metal fine particles are kneaded into the resin component and dispersed in the resin component, excellent conductivity may not be obtained even if a low concentration acid solution is used.

  The network structure in the present invention needs to be a random structure. When the product of the present invention is used by being attached to a display, it is possible to obtain one that does not cause a moire phenomenon by making the network structure random.

  The random network structure is identified by an observation image of a scanning electron microscope, and the network structure is observed in a state where the shape and size of the void portion are not uniform in the shape, that is, a random state. Therefore, the portion of the mesh, that is, the shape of the linear portion is not a straight line but is not uniform in line thickness, that is, is observed as a random state. An example of a random network structure is shown in FIGS. 1 and 4, but is not limited thereto.

  The metal fine particles in the present invention are metal particles having a number average particle diameter of 0.001 to 0.3 μm, and the particle diameter is at most less than 1.0 μm. If the number average particle size and the maximum particle size of the metal fine particles exceed this range, it may be difficult to form a metal fine particle layer in a random network and to obtain a substrate having excellent transparency and electromagnetic shielding properties. . The number average particle diameter of the metal fine particles is preferably 0.001 to 0.2 μm, more preferably 0.002 to 0.15 μm. The particle size distribution of the metal fine particles may be large or small, and the particle size may be irregular or uniform, but if the particle size is uniform and the particle size distribution is small, the metal This is preferable because the fine particle layer can be easily formed into a random network.

  The metal used for the metal fine particles is not particularly limited, and examples thereof include platinum, gold, silver, copper, nickel, palladium, rhodium, ruthenium, bismuth, cobalt, iron, aluminum, zinc, and tin. A metal may be used by 1 type and may be used in combination of 2 or more type.

 In the present invention, it is important that the metal fine particle layers are continuously connected without being divided. Since the metal fine particle layers are connected continuously, if conduction is obtained from a certain point on the metal fine particle layer, it becomes possible to flow electricity over the entire surface of the metal fine particle layer, and good conductivity is exhibited. Furthermore, since the plated metal layer is laminated on the metal fine particle layers that are continuously connected, the plated metal layer can also be continuously connected. As a result, the conductive substrate of the present invention has good conductivity with conduction over the entire surface of the substrate, and can be a substrate excellent in electromagnetic wave shielding properties.

  When the thickness of the metal fine particle layer is thick, the surface specific resistance of the metal fine particle layer becomes small, which is preferable in that the electroplating described later is easily performed. The thickness of the metal fine particle layer in the present invention is preferably 0.2 μm to 7.0 μm, more preferably 0.6 to 4.0 μm. If the thickness is too small, the surface specific resistance may decrease, and if it is too large, the transparency may decrease.

  The surface specific resistance of the metal fine particle layer is preferably 40Ω / □ or less. More preferably, it is 30 ohms / square or less, More preferably, it is 10 ohms / square or less. The surface resistivity is measured, for example, after standing in a normal state (23 ° C., relative humidity 65%) for 24 hours, and in that atmosphere, in accordance with JIS-K-7194, in the form of Loresta-EP (Mitsubishi Chemical Corporation). , Model No .: MCP-T360). When the surface specific resistance is 40Ω / □ or less, it is preferable in that it is easy to perform electrolytic plating described later.

  In the metal fine particle layer in the present invention, in addition to the metal fine particles, various other additives such as a dispersant, a surfactant, a protective resin, an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a pigment, and a dye. Inorganic components such as organic or inorganic fine particles, fillers and antistatic agents, and organic components can also be contained. However, the content of these additives in the metal fine particle layer is preferably less than 50% by weight, that is, the content of the metal fine particles is preferably 50% by weight or more. When the content of the metal fine particles in the metal fine particle layer is 50% by weight or more, the surface specific resistance of the metal fine particle layer tends to be small, which is preferable in terms of easy electroplating described later.

  In the present invention, it is necessary to laminate a plated metal layer on the metal fine particle layer. By laminating the plated metal layer on the metal fine particle layer formed in a random network shape, the random network layer in the present invention is formed. The plated metal layer is a metal layer laminated by electrolytic plating or electroless plating. By laminating the plated metal layer, the conductivity of the conductive substrate becomes good and the electromagnetic wave shielding property becomes good. Moreover, a transparent substrate can be obtained by laminating the plated metal layer only on the metal fine particle layer without laminating the plated metal layer on the opening portion of the mesh formed by the metal fine particle layer.

  Although the metal which comprises a plating metal layer is not specifically limited, Cu, Ni, Cr, Zn, Au, Ag, Al, Sn, Pt, Pd, Co, Fe, In etc. can be used, 1 type or 2 types A combination of the above metals can be used. Among these, it is preferable to use Cu in terms of conductivity, electrolytic plating properties, and the like.

  Since the metal fine particle layer of the present invention has excellent conductivity, it is possible to perform electroplating. In the present invention, the plated metal layer is not laminated on the opening portion of the mesh formed by the metal fine particle layer, but is formed only on the metal fine particle layer to form a transparent substrate. It is preferably formed of an electrically insulating material such as glass or electrically insulating resin.

  As described above, the surface specific resistance of the substrate on which the metal fine particle layer is laminated is preferably 40Ω / □ or less. More preferably, it is 30 ohms / square or less, More preferably, it is 10 ohms / square or less. If it is larger than 40Ω / □, a load due to resistance increases when electrolytic plating is performed, so that it is necessary to apply a high voltage, and as a result, the substrate may be damaged due to heat generation.

  As described above, the content of the metal fine particles contained in the metal fine particle layer is preferably 50% by weight or more. More preferably, it is 70 weight% or more, More preferably, it is 90 weight% or more. When the content of the metal fine particles is 50% by weight or more, the silver fine particle layer tends to have excellent conductivity.

  In the present invention, before performing electroplating on the metal fine particle layer, the conductivity of the metal fine particle layer is increased by using a known method for increasing the conductivity of the metal fine particles, such as heat treatment, light treatment, and current treatment. A treatment for reducing the specific resistance may be performed, and it is particularly preferable to reduce the surface specific resistance by a method of treating metal fine particles with an acid. The method of treating with an acid can be suitably employed even when a material having poor heat resistance and light resistance, such as a thermoplastic resin, is used as the substrate because the conductivity of the metal fine particles can be increased under mild processing conditions. Moreover, since it is a method which does not require a complicated apparatus and process, it is preferable also in terms of productivity.

  A normal temperature is sufficient for the treatment temperature of the acid. When the treatment is performed at a high temperature, acid vapor is generated and the surrounding metal device is deteriorated, which is not preferable. A preferable treatment temperature is 40 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 25 ° C. or lower.

  The acid for treating the metal fine particles is not particularly limited, and can be selected from various organic acids and inorganic acids. Examples of the organic acid include acetic acid, oxalic acid, propionic acid, lactic acid, and benzenesulfonic acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like. These may be strong acids or weak acids. Acetic acid, hydrochloric acid, sulfuric acid, and an aqueous solution thereof are preferred, and hydrochloric acid, sulfuric acid, and an aqueous solution thereof are more preferred.

  The method of treating with an acid is not particularly limited. For example, a substrate in which a metal fine particle layer is laminated in an acid or an acid solution is dipped, an acid or an acid solution is applied on a silver fine particle layer, Alternatively, a method of applying a vapor of an acid solution to the metal fine particle layer is used. Among these, there is a method of directly contacting the substrate and the acid liquid, such as immersing a substrate in which a metal fine particle layer is laminated in an acid solution, or applying an acid or acid solution on the silver fine particle layer. It is preferable because of its excellent conductivity improving effect. In other words, the acid treatment conditions include immersing a substrate in which a metal fine particle layer is laminated in an acid solution at a temperature of 40 ° C. or less, or applying an acid or an acid solution on the silver fine particle layer. Is preferred.

  In the process for producing a conductive substrate, the stage of treatment with acid may be carried out at any stage as long as it is before the plating metal layer is laminated on the metal fine particle layer. For example, a metal fine particle layer may be formed in a network on a substrate and then treated with an acid. A metal group fine particle layer may be laminated on the entire surface of a substrate, then treated with an acid, and then etched to form a metal. The fine particle layer may have a mesh shape. In particular, a method of laminating a metal fine particle layer on a substrate and then treating with an acid is preferably used because it is excellent in the effect of increasing conductivity and is efficient in terms of productivity.

  The treatment time with the acid is sufficient for several minutes or less, and even if the treatment time is made longer, the effect of improving the conductivity may not be increased or the effect of improving the conductivity may be deteriorated. The treatment time with the acid is preferably 15 seconds to 60 minutes, more preferably 15 seconds to 30 minutes, still more preferably 15 seconds to 2 minutes, and particularly preferably 15 seconds to 1 minute.

  When an acid solution is used, the acid concentration is preferably 10 mol / L or less, more preferably 5 mol / L or less, and further preferably 1 mol / L or less. When the concentration of the acid solution is high, workability may deteriorate and productivity may deteriorate, or when a thermoplastic resin film is used as the base material, the base material may be whitened and transparency may be impaired. This is not preferable. In addition, even when the acid concentration is too low, the effect of the treatment with the acid cannot be obtained, so that it is preferably 0.05 mol / L or more, more preferably 0.1 mol / L or more.

  In addition, as described above, when a compound capable of forming metal fine particles, such as metal fine particles, metal oxide fine particles, and organometallic compounds, is kneaded into the resin component and dispersed in the resin component. In some cases, excellent conductivity may not be obtained with a low concentration acid solution as described above.

  On the other hand, when a solution in which at least one selected from metal fine particles, metal oxide fine particles, and organometallic compounds is dispersed or dissolved in a solvent is used, excellent conductivity can be obtained even with a low concentration acid solution.

  If a compound in which a compound capable of forming metal fine particles is dispersed in a resin component is used, excellent conductivity may not be obtained even if a low concentration acid solution as described above is used. On the other hand, when a solution in which at least one selected from metal fine particles, metal oxide fine particles, and organometallic compounds is dispersed or dissolved in a solvent is used, the effect of improving conductivity is exhibited by a low-concentration acid solution. The mechanism to do this is not clear, but is presumed as follows.

  In other words, the dispersion state in the resin component is formed because the portion where the concentration of the compound capable of forming the metal fine particles is high or low is likely to be generated, and the dispersion state of the compound capable of forming the metal fine particles is uneven. In addition, even when the amount of the resin component added is small, the metal fine particle layer has a place where the amount of the resin component that fills the space between the metal fine particles is extremely large, and in order to remove the resin, the resin component is removed with a high concentration of acid. An etching process may be required. On the other hand, in a solution in which at least one selected from metal fine particles, metal oxide fine particles, and organometallic compounds is dispersed or dissolved in a solvent, the compounds capable of forming the metal fine particles have no uneven concentration depending on the location. Since a uniform dispersed state is likely to occur, the formed metal fine particle layer is less likely to have a place where the amount of other insulating components filling the space between the metal fine particles is extremely large. Therefore, it is presumed that a treatment that etches other insulating components with a high concentration of acid is not required, and a sufficient treatment effect is exhibited even with a low concentration acid solution.

  Moreover, it is preferable to treat the metal fine particle layer with an organic solvent before treating with the acid. If the metal fine particle layer is treated with an organic solvent before being treated with an acid, more excellent conductivity can be easily obtained.

  The step of treating the metal fine particle layer with the organic solvent may be performed by laminating the metal fine particle layer on the substrate in a network and then treating with the organic solvent. After laminating the metal fine particles on the entire surface of the substrate, the organic solvent Then, the metal fine particle layer may be formed into a network by etching or the like. Among these, a method of laminating metal fine particles on a substrate in a network and then treating with an organic solvent is preferably used because it is excellent in the effect of increasing conductivity and is efficient in terms of productivity. Before or after the treatment with the organic solvent, another layer may be printed on or coated on the substrate on which the metal fine particle layer is laminated. Further, before or after the treatment with the organic solvent, the substrate on which the metal fine particle layer is laminated may be dried, heat-treated, or subjected to an ultraviolet irradiation treatment.

  The treatment temperature of the organic solvent is sufficient at room temperature. When the treatment is performed at a high temperature, when a thermoplastic resin film is used as the base material, the base material may be whitened and transparency may be impaired. A preferable treatment temperature is 40 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 25 ° C. or lower.

  The method of treating with an organic solvent is not particularly limited. For example, the substrate on which the metal fine particle layer is laminated is immersed in a solution of the organic solvent, the organic solvent is applied on the metal fine particle layer, or the vapor of the organic solvent is applied to the metal. A method of hitting the fine particle layer is used. Among these, a method of immersing a substrate in which a metal fine particle layer is laminated in an organic solvent or coating an organic solvent on the metal fine particle layer is preferable because of its excellent conductivity improving effect.

  Examples of organic solvents include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol, 3-methoxy-3-methyl-1-butanol, 1,3-butanediol, 3-methyl-1,3- Alcohols such as butanediol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and cyclopentanone, esters such as ethyl acetate and butyl acetate, alkanes such as hexane, heptane, decane and cyclohexane, N-methyl Dipolar aprotic solvents such as -2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, toluene, xylene, aniline, ethylene glycol butyl ether, ethylene glycol, ethyl ether, ethylene glycol Ether, chloroform and the like, and mixed solvents thereof can be used. Among these, when ketones, esters, and toluene are contained, the conductivity improving effect is excellent, which is preferable, and ketones are particularly preferable.

  An organic solvent diluted with water may be used. The mixing ratio of the organic solvent and water is preferably 5/95 or more by weight, more preferably 50/50 or more, still more preferably 70/30 or more, and most preferably 100/0.

  In addition, when the metal fine particle layer is formed of noble metal fine particles, it acts as a catalyst for electroless plating, so that electroless plating can be performed. Examples of the noble metal include Au, Ag, Pt, Pd, Rh, Os, Ru, and Ir.

 In the present invention, the plated metal layer is not laminated on the opening portion of the mesh formed by the metal fine particle layer, but is formed only on the metal fine particle layer to form a transparent substrate. It is preferable that no compound such as Au, Ag, Pt, Pd, or the like that can serve as a catalyst for electroless plating is not present in.

  In electroless plating, it is necessary to lengthen the plating time in order to increase the thickness of the plated metal layer. In this case, plating nuclei are formed on the foreign matter adhering to the opening, and plating is formed on the opening. May occur. When plating occurs also in the opening portion, the problem that transparency is lowered occurs. Therefore, when it is desired to increase the thickness of the plating metal layer, it is more preferable to laminate the plating metal layer by electrolytic plating. .

  At least the thickness of the plated metal layer on one side needs to be 1.5 μm or more. Preferably it is 2.0 micrometers or more, More preferably, it is 3.0 micrometers or more. The upper limit is not particularly limited. However, if the thickness of the plated metal layer is increased, the line width of the plated metal layer is likely to be increased at the same time. As a result, the transparency of the substrate is lowered. More preferably, it is 10 μm or less. In the present invention, by setting the thickness of the plated metal layer to 1.5 μm or more, the magnetic field shielding property in the low frequency region can be excellent.

  When the thickness of the plated metal layer is 1.5 μm or more, the spread in the width direction of the plated metal layer inevitably increases. Therefore, when a regular pattern is used, a moire phenomenon is likely to occur. However, since a random layer is formed in the present invention, no moire occurs even if the plating metal layer thickness is increased. As a result, it is possible to achieve both magnetic field shielding properties in a low frequency region.

  As described above, in the present invention, since the thickness of the plated metal layer is 1.5 μm or more, the spread of the plated metal layer in the width direction inevitably increases, and the line width of the random network layer tends to be large. However, considering the effect of improving the magnetic field shielding property in the low frequency region, it is preferable that the plated metal layer is thick and the random mesh layer has a large line width. In the present invention, since the mesh layer is random, the moire phenomenon does not occur even if the line width of the random mesh layer is large, and thus such a form can be taken.

  The line width of the random network layer is preferably larger than 15 μm in order to obtain good electromagnetic shielding properties. More preferably, it is larger than 15 μm and not larger than 50 μm, more preferably larger than 20 μm and not larger than 45 μm, particularly preferably larger than 25 μm and not larger than 40 μm. When the line width is larger than 50 μm, the transparency may be lowered.

  The surface specific resistance of at least one surface of the conductive substrate in the present invention needs to be smaller than 0.5Ω / □. Preferably it is 0.2 ohm / square or less, More preferably, it is 0.1 ohm / square or less, More preferably, it is 0.05 ohm / square or less. When the surface specific resistance is 0.5Ω / □ or more, the magnetic field shielding property in the low frequency region cannot be exhibited well.

 Although it does not specifically limit in order to make the surface specific resistance of an electroconductive board | substrate 0.5 ohm / square or less, As a metal which comprises a plating metal layer, Cu, Ni, Cr, Zn, Au, Ag, Al, Sn, Pt, It is preferable to use one or a combination of two or more metals selected from Pd, Co, Fe, and In, and among these, Cu is preferably used. By using the above metal, the surface specific resistance can be suitably 0.5 Ω / □ or less by setting the thickness of the plated metal layer to 1.5 μm or more.

  The substrate in the present invention is not particularly limited, and various substrates such as glass and resin can be used. Further, a combination of two or more substrates such as glass and resin may be used.

  When a board | substrate is a thermoplastic resin film, it is preferable at points, such as transparency, a softness | flexibility, and workability. When a process for increasing the conductivity of the silver fine particle layer is required when a thermoplastic resin film is used as the substrate, the above-described treatment with an acid can be suitably used. If the treatment with an acid is performed, the conductivity of the silver fine particle layer can be increased without the need for heat treatment for a long time at such a high temperature that the thermoplastic resin film melts and deforms.

  The thermoplastic resin film as used in the present invention is a general term for films that are melted or softened by heat, and is not particularly limited, but representative examples include polyolefins such as polyester films, polypropylene films, and polyethylene films. Films, polylactic acid films, polycarbonate films, acrylic films such as polymethyl methacrylate films and polystyrene films, polyamide films such as nylon, polyvinyl chloride films, polyurethane films, fluorine films, polyphenylene sulfide films, and the like can be used.

  These may be homopolymers or copolymerized polymers. Of these, polyester films, polypropylene films, polyamide films and the like are preferable in terms of mechanical properties, dimensional stability, transparency, and polyester films are particularly preferable in terms of mechanical strength and versatility.

  In the polyester film, polyester is a general term for polymers having an ester bond as a main bond chain, and includes ethylene terephthalate, propylene terephthalate, ethylene-2,6-naphthalate, butylene terephthalate, propylene-2,6. -What uses as a main structural component at least 1 sort (s) chosen from naphthalate, ethylene-alpha, beta-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate etc. can be used preferably. . These constituent components may be used alone or in combination of two or more. However, when quality, economy and the like are comprehensively judged, polyester having ethylene terephthalate as a main constituent, that is, polyethylene terephthalate is used. It is particularly preferable to use it. In addition, when heat or shrinkage stress acts on the substrate, polyethylene-2,6-naphthalate having excellent heat resistance and rigidity is more preferable. These polyesters may further be partially copolymerized with other dicarboxylic acid components and diol components, preferably 20 mol% or less.

  The polyester also contains various additives such as antioxidants, heat stabilizers, weathering stabilizers, UV absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents. An agent, a nucleating agent, etc. may be added to such an extent that the properties are not deteriorated.

  The intrinsic viscosity (measured in o-chlorophenol at 25 ° C.) of the above polyester is preferably 0.4 to 1.2 dl / g, more preferably 0.5 to 0.8 dl / g. This is suitable for carrying out the present invention.

  The polyester film using the polyester is preferably biaxially oriented. A biaxially oriented polyester film is generally an unstretched polyester sheet or film that is stretched about 2.5 to 5 times in the longitudinal direction and in the width direction, and then subjected to heat treatment to complete crystal orientation. It is a thing which shows a biaxially oriented pattern by wide-angle X-ray diffraction.

  The thickness of the polyester film is not particularly limited and is appropriately selected depending on the application and type, but from the viewpoint of mechanical strength, handling properties, etc., it is usually preferably 10 to 500 μm, more preferably 38 to 250 μm, most preferably 75 to 150 μm. Further, the polyester film substrate may be a composite film by coextrusion. On the other hand, the obtained film can also be used by bonding by various methods.

  Various layers may be laminated on the conductive substrate of the present invention in addition to the substrate, the metal fine particle layer, and the plated metal layer. For example, although not particularly limited, an undercoat layer for improving adhesion may be provided between the substrate and the metal fine particle layer, or a protective layer may be provided on the plated metal layer. In addition, an adhesive layer, a release layer, a protective layer, an adhesion-imparting layer, a weather-resistant layer, or the like may be provided on one side or both sides of the substrate.

  Further, the metal fine particle layer or the plated metal layer may be subjected to an antiglare treatment or may be provided with an antiglare layer. For example, blackening treatment by metal oxidation, black plating such as chromium alloy and nickel alloy, and application of black or dark ink can be performed.

  In the present invention, an antiglare treatment is performed on the plated metal layer or the antiglare layer is laminated, so that the maximum reflectance of the visible light region on at least one surface of the surface on which the random network layer is laminated is 20% or less. It is preferable. When such an anti-glare property is imparted, for example, when it is used as a display electromagnetic wave shielding substrate provided on the front surface of the display, it is preferable because the problem that it becomes difficult to see images and characters due to the reflection of the substrate is improved. If the maximum reflectance in the visible light region is greater than 20%, images and characters may be difficult to see due to the reflection of the substrate. The maximum reflectance in the visible light region is preferably 15% or less, more preferably 10% or less, and further preferably 5% or less.

 Although the manufacturing method of the electroconductive board | substrate of this invention is illustrated and demonstrated more concretely, it is not limited to this.

  A silver fine particle paste is printed on a biaxially stretched polyester film in a random network by screen printing, and a silver fine particle layer is laminated in a random network structure.

  Thereafter, in order to treat the silver fine particle layer with an acid, the biaxially stretched polyester film is placed in 1N hydrochloric acid and allowed to stand for several seconds to 60 minutes. Thereafter, the biaxially stretched polyester film is taken out, washed with water and dried.

  Next, the conductive substrate of the present invention can be prepared by immersing the biaxially stretched polyester film in an electrolytic plating bath made of a copper sulfate solution and energizing it, and laminating a plated metal layer on the silver fine particle layer.

  The conductive substrate of the present invention is a conductive substrate that satisfies the three characteristics of being transparent, free of moire phenomenon, and having excellent magnetic field shielding properties in a low frequency region.

[Characteristic measurement method and effect evaluation method]
The method for measuring the characteristics of the conductive substrates prepared in each of the examples and comparative examples and the method for evaluating the effects are as follows.

(1) Number average particle diameter and maximum particle diameter of metal fine particles A solution in which metal fine particles are dispersed is applied on a copper mesh and observed with a transmission electron microscope (H-7100FA type, manufactured by Hitachi, Ltd.). Thus, the number average particle diameter and the maximum particle system of the metal fine particles were obtained. The particle diameter of 100 metal fine particles was measured, and the number average particle diameter was an average value of the 100 particle diameters. The maximum particle size was the maximum of the 100 particle sizes.

(2) Surface observation The surface of the conductive substrate was observed with an electron microscope (LEICA DMLM manufactured by Leica Microsystems) at a magnification of 100 to observe the shape of the mesh.

(3) Line width of random network layer The surface of the conductive substrate was observed with an electron microscope (LEICA DMLM manufactured by Leica Microsystems) at a magnification of 100 times, and the observed image was image processing software (manufactured by Inspector Matrox). Was used to determine the line width of the random network layer.

  The image observed with a microscope is displayed on a display having pixels that are square (this display image is used as an original image, see FIG. 1). Then, using the above processing software, the random mesh layer portion was binarized to black and white so that the other portion (mesh opening portion) was white (this binarized image was binarized image) (See FIG. 2). At this time, the threshold value for the binarization process is selected so that the line width of the random mesh layer portion in the central portion of the original image and the line width of the random mesh layer portion in the central portion of the binarized image are the same. Next, after performing the black and white reversal processing of the binarized image, the number of pixels in which the random mesh layer portion (white portion) of the black and white reversal image was drawn was obtained. The obtained number of pixels was multiplied by the area per pixel to obtain the area (S) of the random mesh layer.

 Next, using the above-described processing software, thinning processing is performed on the random mesh layer portion (white portion) of the binarized image subjected to the black and white inversion processing, and the random mesh layer portion (white portion) corresponds to one pixel. Thinned until. Then, the number of pixels depicting the thinned random mesh layer portion (white portion) of the thinned image was obtained. The obtained number of pixels is multiplied by the length per pixel, and this is used as the length (L) of the random mesh layer (in FIG. 3, the random mesh layer is black, and other portions (mesh openings) The thinned image is further subjected to black-and-white reversal processing so that becomes white.

  As described in the new experimental image processing (published by Links Publishing Division), the thinning process is a process of connecting components until the width becomes 1 (one pixel in the present invention). This is an operation to remove one peripheral pixel in order from the one that can be erased (one pixel can be erased means that the number of connected components and the number of holes in the image change even if that pixel is erased) It means not.)

Using the values of S and L determined above, the line width of the random network layer was determined by the following formula (1).
-Line width of random network layer = S / L (1).

  The length and area per pixel described above were obtained as follows.

  A scale with a scale of 10 μm was observed at a magnification of 100 times with an electron microscope (LEICA DMLM manufactured by Leica Microsystems). A length of 100 μm was taken from the observed image, and a line having a length corresponding to the length was drawn on the image. Next, an image in which only the line is projected is created, and the image is binarized into black and white using the above-described processing software so that the line is white and the other part is black. Thinning processing was performed until the thickness of the portion (white portion) became the thickness of one pixel. Then, the number of pixels of the thinned line portion (white portion) was obtained, and the length per pixel was obtained by dividing the line length of 100 μm by the obtained number of pixels.

  Furthermore, since the measurement was performed using a display having a square pixel, the area per pixel was the square of the length per pixel.

(4) Thickness of silver fine particle layer and plated metal layer After cutting out the cross section of the conductive substrate, the cross section is observed with a field emission scanning electron microscope in the same manner as (2) surface observation. The thickness of was observed.

In one cross section, the thickness of the portion where the total thickness of the metal fine particle layer and the plated metal layer is maximum is _Tt, and the thickness of the portion where the thickness of the metal fine particle layer is maximum is _Tm . Then, (T _t −T _m ) is the thickness of the plated metal layer in this section, and T _m is the thickness of the metal fine particle layer in this section. This was performed at 10 cross-sections, and the average value at 10 locations was defined as the thickness of the metal particle layer of the conductive substrate and the thickness of the plated metal layer.

  Here, when the random network layer was laminated on both surfaces of the substrate, the average of one surface and the average of the other surface were determined, and the thickness of each surface was determined.

(5) Total light transmittance The total light transmittance was measured under the normal condition (23 ° C., relative humidity 65%) after leaving the conductive substrate for 2 hours, and then fully automatic direct reading haze computer “HGM-” manufactured by Suga Test Instruments Co., Ltd. 2DP ". The average value measured three times was defined as the total light transmittance of the conductive substrate. In addition, when the random network layer was laminated | stacked only on the single side | surface of the board | substrate, the electroconductive board | substrate was installed so that light may enter from the surface side which laminated | stacked the random network layer.

(6) Surface specific resistance The surface specific resistance was measured by leaving the conductive substrate in a normal state (23 ° C., relative humidity 65%) for 24 hours and then in the atmosphere in accordance with JIS-K-7194. -EP (Mitsubishi Chemical Corporation make, model number: MCP-T360) can be used for measurement. However, in this application, the number of samples to be measured was one, five points were measured for each sample, and the average of the five points was defined as the surface specific resistance. Moreover, when the random network layer is laminated on both surfaces of the substrate, the average of the five points measurement on one side and the average of the five points measurement on the other side were obtained, respectively, and the surface specific resistance for each side was obtained. .

(7) Moire-resistant phenomenon The anti-moire phenomenon is caused by using a high-definition plasma display TH-42PHD7 manufactured by Matsushita Electric Industrial Co., Ltd. as a plasma display, and the screen and the conductive substrate are almost parallel in front of the screen on which the image is projected. The substrate was held in such a manner that the substrate was rotated 360 ° while keeping the screen and the substrate surface substantially parallel, and it was evaluated by visually observing whether the moire phenomenon occurred during the rotation. The case where moiré was not observed was marked with ◯, and the case where moire was observed was marked with x. In addition, when the random network layer was laminated | stacked only on the single side | surface of the board | substrate, the electroconductive board | substrate was held so that the surface side which has not laminated | stacked the random network layer may oppose a display screen.

(8) Electromagnetic wave shielding property The conductive substrate was cut into 20 cm × 20 cm, and the electromagnetic wave shielding property was measured by the KEC method of Kansai Electronics Industry Promotion Center. The measurement was performed in a frequency range from 0.1 to 1000 MHz. Regarding the electric field shielding property, the electric field shielding property at 300 MHz was evaluated. Regarding the magnetic field shielding property, the magnetic field shielding property at 10 MHz was evaluated in order to evaluate the magnetic field shielding property in the low frequency region. In the evaluation of the KEC method, an electrode having an electrolytic shielding effect of 40 dB or more at 300 MHz and a magnetic field shielding effect of 5 dB or more at 10 MHz was regarded as acceptable. In addition, both the electrolytic shielding property and the magnetic field shielding property were measured three times for one sample, and the average was obtained.

(9) Maximum reflectance in the visible light region The maximum reflectance in the visible light region was determined by measuring the random mesh layer side of the conductive substrate using a U-3410 type self-recording spectrophotometer manufactured by Hitachi, Ltd. . Measurement was performed in the visible light range of 380 nm to 780 nm, and the highest reflectance in the measurement range was defined as the maximum reflectance in the visible light region. Measurement was performed three times for each sample, and the average was obtained.

 The test specimen for measurement was colored with black magic ink (registered trademark) on the back surface of the measurement surface in order to eliminate back surface reflection.

  In addition, when random mesh layers were laminated on both sides, the measurement was performed on each side, so separate test pieces were prepared and measured on each side.

(10) Anti-glare A high-definition plasma display manufactured by Matsushita Electric Industrial Co., Ltd. A TH-42PHD7 is connected to a notebook computer, the screen background is white, and there is a black gothic font with a size of 40 points. An image depicting one character was projected so that the image was displayed on the entire plasma display screen. The size of the letters “A” projected was about 4 cm in width and about 3.5 cm in length.

 Subsequently, the conductive substrate cut to 5 cm × 5 cm was bonded to the display so as to overlap the characters on the display.

  Next, the conductive substrate bonded to the display was illuminated with a flashlight using a high-top bean cucumber (0.72 V, 0.7 A) at a distance of 10 cm from the front.

  At this time, at a position 50 cm away from the substrate, characters on the back of the substrate were visually observed from above 45 ° with respect to the substrate surface to determine whether or not the characters could be recognized, and the antiglare property was evaluated.

  When the conductive substrate was bonded to the display so as to overlap the characters of the display, the bonding was performed so that the surface on which the random mesh layer was laminated was on the viewer side.

 Moreover, when the random network layer was laminated | stacked on both surfaces of the board | substrate, it bonded together so that a surface with the smaller maximum reflectance of a visible light area | region may become an observer side.

  Next, the present invention will be described based on examples.

(Metal fine particle layer forming paste)
As the fine metal particle layer forming paste, XA-9053 manufactured by Fujikura Kasei Co., Ltd., which is a fine silver particle layer forming paste, was used. The number average particle size of the silver fine particles was 0.04 μm, and the maximum particle size was 0.2 μm or less.

(Metal fine particle layer forming solution)
As the metal fine particle layer forming solution, CE103-7 manufactured by Cima NanoTech, which is a silver fine particle layer forming solution, was used. (Electrolytic Cu plating solution 1)
6 L of a copper sulfate solution SG (Meltex Co., Ltd.) was added to 7 L of water and stirred. Next, 2.1 L of 97% sulfuric acid (Ishizu Pharmaceutical Co., Ltd., 97% sulfuric acid reagent grade) was added, and then 28 mL of 1N hydrochloric acid (N / 1-hydrochloric acid manufactured by Nacalai Tesque) was added. Further, 100 mL each of Capper Gream CLX-A and CLX-C manufactured by Roll & Haas Electronic Materials Co., Ltd. was added in this order as a copper sulfate plating brightener to this solution, and finally water was added to complete the entire solution. 20L.

Example 1
A metal fine particle layer-forming paste is printed on one side of a biaxially stretched polyethylene terephthalate film (Lumirror (registered trademark) U94 manufactured by Toray Industries, Inc.) in a random mesh pattern by screen printing and dried at 180 ° C. for 1 minute. Then, a laminated substrate in which silver fine particle layers were laminated in a random network shape was obtained. The mesh had a line thickness of 2 μm and a line width of 35 μm.

  Subsequently, in order to treat the silver fine particle layer of this film with an acid, the film was immersed in 1N hydrochloric acid (N / 1-hydrochloric acid manufactured by Nacalai Tesque) at 25 ° C. for 1 minute, and then the film was taken out and washed with water. After that, the film was dried at 150 ° C. for 1 minute in order to remove moisture. The surface specific resistance of this film was 1Ω / □.

In order to laminate a plated metal layer on the silver fine particle layer of this film, electrolytic Cu plating solution 1 was used, and an electric current of 0.3 A was applied per 100 cm ^{2 of} film to perform electrolytic Cu plating for 27 minutes. Thereafter, the film was taken out and washed with water, and then the film was dried at 120 ° C. for 1 minute in order to remove moisture, thereby obtaining the conductive substrate of the present invention.

 The total light transmittance of this substrate was 67%, and it was a substrate with excellent transparency. The maximum reflectance in the visible light region was 35%, and as a result of anti-glare evaluation, characters could not be recognized.

(Example 2)
A sample was prepared in the same manner as in Example 1 except that the electrolytic Cu plating time was 7 minutes. This substrate had a total light transmittance of 73% and was a substrate excellent in transparency. The maximum reflectance in the visible light region was 29%, and as a result of anti-glare evaluation, characters could not be recognized.

(Example 3)
A sample was prepared in the same manner as in Example 2 except that the fine metal particle layer forming paste was screen-printed so that the mesh line thickness was 0.6 μm. This substrate had a total light transmittance of 73% and was a substrate excellent in transparency. The maximum reflectance in the visible light region was 29%, and as a result of anti-glare evaluation, characters could not be recognized.

Example 4
In order to further anti-glare the plated metal layer on the substrate prepared in Example 2, the substrate was immersed in Meltex Co., Ltd. Enplate MB-438 at 80 ° C. for 3 minutes to perform an oxidation blackening treatment. It was. This substrate had a total light transmittance of 73% and was a substrate excellent in transparency. The maximum reflectance in the visible light region was 5%, and as a result of evaluating the antiglare property, characters could be recognized.

(Example 5)
As an anti-glare treatment, a current of 0.1 A per 100 cm ^{2 of} film was passed using an enplate electrolytic Ni plating solution Z-80 manufactured by Meltex Co., Ltd., and electrolytic blackening Ni plating was performed at 28 ° C. for 5 minutes. A sample was prepared in the same manner as in Example 4 except that a dark color antiglare layer was laminated. The maximum reflectance in the visible light region was 9%, and as a result of evaluating the antiglare property, characters could be recognized.

(Example 6)
In order to further anti-glare the plated metal layer on the substrate prepared in Example 1, the substrate was immersed in Meltex Co., Ltd. Enplate MB-438 at 80 ° C. for 3 minutes to perform an oxidation blackening treatment. It was. The total light transmittance of this substrate was 67%, and it was a substrate with excellent transparency. The maximum reflectance in the visible light region was 5%, and as a result of evaluating the antiglare property, characters could be recognized.

(Example 7)
As an anti-glare treatment, a current of 0.1 A per 100 cm ^{2 of} film was passed using an enplate electrolytic Ni plating solution Z-80 manufactured by Meltex Co., Ltd., and electrolytic blackening Ni plating was performed at 28 ° C. for 5 minutes. A sample was prepared in the same manner as in Example 6 except that a dark antiglare layer was laminated. The maximum reflectance in the visible light region was 9%, and as a result of evaluating the antiglare property, characters could be recognized.

(Example 8)
One minute elapsed at 25 ° C after applying the metal fine particle layer forming solution on the hydrophilized layer of a biaxially stretched polyethylene terephthalate film (Lumirror (registered trademark) U46 manufactured by Toray Industries, Inc.) that had been hydrophilized on one side Then, the silver fine particles were self-assembled into a mesh shape, and a silver fine particle layer was laminated in a random network shape, and then treated at 150 ° C. for 1 minute. Next, each film was immersed in 25 ° C. acetone (special grade manufactured by Nacalai Tesque Co., Ltd.) for 30 seconds, the film was taken out, and dried at 25 ° C. for 3 minutes. Subsequently, the whole film was immersed in 1N (1 mol / L) hydrochloric acid (N / 10-hydrochloric acid manufactured by Nacalai Tesque Co., Ltd.) at 25 ° C. for 1 minute, taken out, washed with water, and dried at 150 ° C. for 1 minute. The surface specific resistance of this film was 4Ω / □.

In order to laminate a plating metal layer on the silver fine particle layer of this film, electrolytic Cu plating solution 1 was used, and an electric current of 0.3 A was applied per 100 cm ^{2 of} film to perform electrolytic Cu plating for 14 minutes. Thereafter, the film was taken out and washed with water, and then the film was dried at 120 ° C. for 1 minute in order to remove moisture, thereby obtaining the conductive substrate of the present invention.

 This substrate had a total light transmittance of 73% and was a substrate excellent in transparency. The maximum reflectance in the visible light region was 31%, and as a result of anti-glare evaluation, characters could not be recognized.

Example 9
A sample was prepared in the same manner as in Example 8 except that the electrolytic Cu plating time was 9 minutes. The total light transmittance of this substrate was 75%, and the substrate was excellent in transparency. The maximum reflectance in the visible light region was 30%, and as a result of anti-glare evaluation, characters could not be recognized.

(Example 10)
A substrate was prepared in the same manner as in Example 8 except that the treatment with acetone was not performed. The surface specific resistance of the film before laminating the plating metal layer was 12Ω / □. The total light transmittance of the substrate after the plating metal layer was laminated was 73%, and the substrate was excellent in transparency. The maximum reflectance in the visible light region was 31%, and as a result of anti-glare evaluation, characters could not be recognized.

(Example 11)
In order to further anti-glare the plated metal layer on the substrate prepared in Example 8, the substrate was immersed in Meltex Co., Ltd. Enplate MB-438 at 58 ° C. for 5 minutes to perform an oxidation blackening treatment. It was. This substrate had a total light transmittance of 73% and was a substrate excellent in transparency. The maximum reflectance in the visible light region was 5%, and as a result of evaluating the antiglare property, characters could be recognized.

(Comparative Example 1)
A sample was prepared in the same manner as in Example 1 except that the electrolytic Cu plating time was 4 minutes. In this substrate, the thickness of the plated metal layer was thin, and the magnetic field shielding property in the low frequency region was insufficient.
The maximum reflectance in the visible light region was 28%, and as a result of evaluating the antiglare property, characters could not be recognized.

(Comparative Example 2)
A sample was prepared in the same manner as in Example 1 except that the metal fine particle layer forming paste was screen-printed so that the line width of the mesh was 40 μm. The total light transmittance of this substrate was 65%, and the transparency was insufficient. The maximum reflectance in the visible light region was 35%, and as a result of anti-glare evaluation, characters could not be recognized.

(Comparative Example 3)
In order to further blacken the plated metal layer on the substrate prepared in Example 3, the substrate was immersed in Meltex Co., Ltd. Enplate MB-438 at 80 ° C. for 5 minutes to perform an oxidation blackening treatment. . This substrate was inferior in surface resistivity, and the magnetic field shielding property in the low frequency region was insufficient. The maximum reflectance in the visible light region was 5%, and as a result of evaluating the antiglare property, characters could be recognized.

(Comparative Example 4)
A silver paste AGEP-201X manufactured by Sumitomo Electric Industries, Ltd. was screen-printed on a biaxially stretched polyethylene terephthalate film (Lumirror (registered trademark) U94 manufactured by Toray Industries, Inc.). The maximum particle system of silver powder contained in the silver paste is Since it was 1 μm or more, a line width of 50 μm and a thick mesh were printed. Next, electrolytic copper plating was performed on the obtained silver powder network layer in the same manner as in Comparative Example 1 to prepare a sample. This substrate has a problem that the total light transmittance is 65% and the transparency is insufficient, the thickness of the plated metal layer is thin, and the magnetic field shielding property in the low frequency region is insufficient. The maximum reflectance in the visible light region was 28%, and as a result of evaluating the antiglare property, characters could not be recognized.

(Comparative Example 5)
A thermosetting conductive silver paste DW-250H-5 manufactured by Toyobo Co., Ltd. was screen-printed on a biaxially stretched polyethylene terephthalate film (Lumirror (registered trademark) U94 manufactured by Toray Industries, Inc.) to obtain a line thickness of 3 μm and a line width of 50 μm. A sample was prepared in the same manner as in Example 2 except that a grid having a pitch of 300 μm was printed, heat-treated at 150 ° C. for 30 minutes, and a regular lattice network was laminated. This substrate was moire.

  The evaluation results of Examples 1 to 11 and Comparative Examples 1 to 5 are shown in Table 1.

  Table 2 shows the evaluation results of the maximum reflectance and the antiglare property in the visible light region of Examples 1 to 11 and Comparative Examples 1 to 4.

  The conductive substrate of the present invention is transparent, does not cause a moiré phenomenon, and is excellent in magnetic field shielding properties particularly in a low frequency region that is characteristically required for a plasma display panel. Therefore, it can be suitably used as an electromagnetic shielding member of a plasma display panel, and since it has excellent transparency and conductivity, it can be suitably used for various circuit boards and solar cell applications.

It is a figure explaining the line | wire width measurement of a random mesh layer part. (Original image. The black part is the random mesh layer.) It is a figure explaining the line | wire width measurement of a random mesh layer part. (Binarized image. Black part is random mesh layer part.) It is a figure explaining the line | wire width measurement of a random mesh layer part. (Thinned image. Black part is random mesh layer part.) It is an example of a random network structure.

Claims (12)

A conductive substrate having a random network layer in which a metal fine particle layer is laminated in a random network shape on at least one surface of the substrate, and a plating metal layer is laminated on the metal fine particle layer,
The thickness of the plated metal layer on at least one side of the conductive substrate is 1.5 μm or more;
The total light transmittance of the conductive substrate is larger than 65%, and the surface specific resistance of at least one surface of the conductive substrate is smaller than 0.5Ω / □,
Conductive substrate.   The conductive substrate according to claim 1, wherein a line width of the random network layer laminated on at least one surface of the substrate is larger than 15 μm.  The conductive substrate according to claim 1 or 2, wherein a maximum reflectance of a visible light region in at least one surface of the surface on which the random network layer is laminated is 20% or less.   The electromagnetic wave shield substrate for plasma displays using the electroconductive board | substrate in any one of Claims 1-3.   After the metal fine particle layer is laminated in a random network shape on at least one surface of the substrate, the metal fine particle layer is subjected to an acid treatment, and the metal layer is laminated on the metal fine particle layer by plating to form a random network layer. The manufacturing method of the electroconductive board | substrate in any one of Claims 1-3.   The method for producing a conductive substrate according to claim 5, wherein the plated metal layer is laminated by electrolytic plating.   7. The acid treatment of the metal fine particle layer is to immerse a substrate on which the metal fine particle layer is laminated in an acid solution and / or to apply an acid solution to the substrate on which the metal fine particle layer is laminated. The manufacturing method of the electroconductive board | substrate of description.   The method for producing a conductive substrate according to claim 5, wherein the treatment is performed with an acid solution at 40 ° C. or lower.   The method for producing a conductive substrate according to claim 5, wherein the treatment is performed with an acid solution of 5 mol / L or less.   The method for producing a conductive substrate according to claim 5, wherein the metal fine particle layer is treated with an organic solvent and then treated with an acid.   The metal fine particle layer is laminated by applying a solution in which at least one selected from the group consisting of metal fine particles, metal oxide fine particles, and organometallic compounds is dispersed or dissolved in a solvent to the substrate. The manufacturing method of the electroconductive board | substrate in any one.   The method for producing a conductive substrate according to claim 11, wherein the solution applied to the substrate is a solution that self-assembles into a mesh shape.

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