JP2006313891A - Conductive substrate and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a conductive substrate which has transparency and high-level conductivity, and is used for an electromagnetic shield film, etc. <P>SOLUTION: In the manufacturing method of the conductive substrate having a metal particulate layer laminated in a mesh shape on at least one surface of the substrate, the metal particulate layer is processed with acid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a conductive substrate excellent in transparency, conductivity, and productivity, and a conductive substrate obtained by the production method. More specifically, for example, a plasma display panel, a liquid crystal television, and the like The present invention relates to a conductive substrate for an electromagnetic wave shielding substrate suitably used for a flat panel display, and a method for producing the conductive substrate.

  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 that are growing rapidly, strong electromagnetic waves are emitted from flat panel displays such as plasma display panels and liquid crystal televisions, and there is concern about the effects on the human body. Since these displays observe images at a relatively short 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.

  In general, a transparent conductive substrate is used for an electromagnetic wave shielding substrate used in a display panel, and various methods are employed for manufacturing a conductive substrate for an electromagnetic wave shielding substrate that is currently used. Yes. For example, a copper foil is bonded to a polyester film, a regular mesh shape is patterned by photolithography, and the copper foil is etched into a mesh shape, thereby creating a mesh-like conductive film whose conductive portion is copper. (Patent Document 1).

In addition, as a method of manufacturing a conductive substrate provided with a patterned conductive layer, for example, a method of providing a conductive layer of metal fine particles by printing a metal fine particle solution on the substrate has been proposed (Patent Document 2). 3). Generally, in order to increase the conductivity of the metal fine particle layer, a heat treatment for a long time or a long time is necessary, but for a heat treatment for a long time at a high temperature, for example, when a thermoplastic resin such as a polyester film is used as a substrate, There were problems such as deformation of the thermoplastic resin. In order to solve this problem, methods for increasing the conductivity of the metal fine particle layer without using high-temperature and long-time heat treatment have been proposed (Patent Documents 2 to 5).
: JP-A-2001-210988 (first page, claims, etc.) : JP 2004-79243 A (first page, claims, etc.) : JP-A-2004-207558 (first page, claims, etc.) : JP-A-2005-32458 (first page, claims, etc.) : JP 2004-127851 A (first page, claims, etc.)

  However, the above-described conventional technique has the following problems.

  The method of etching a copper foil described in Patent Document 1 is an excellent method for obtaining a highly accurate mesh shape, but generally includes a process of bonding a copper foil, a photolithography process, an etching process, and the like. The rate is bad and product loss in each process is likely to occur. In particular, there are many environmental issues such as the generation of harmful waste liquid in the etching process. Furthermore, if copper foil is used as a material and then the copper foil is etched to increase permeability, it is necessary to dissolve a large part of the copper foil by etching to make a waste liquid, which is an aspect of material recycling. But there are many challenges.

  The method for obtaining a conductive layer of metal fine particles by printing a metal fine particle solution described in Patent Documents 2 to 5 requires some kind of treatment because sufficient conductivity cannot be obtained only by printing.

  Patent Document 2 proposes a method for energizing and sintering a metal fine particle layer as a process for enhancing conductivity, but in order to energize, special devices and operations such as connection of a power source and terminals are required. There are problems such as becoming.

  In Patent Documents 3 to 5, as a process for increasing conductivity, an ink-jet receiving layer, an intermediate layer made of a hydrophilic resin with a limited average surface roughness, and a receiving layer containing a porous inorganic filler are used to form a metal. Providing a fine particle layer has been proposed, but it is necessary to provide a special receiving layer and intermediate layer in advance on the base material. there were.

  An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a method for producing a conductive substrate having transparency and conductivity.

  The present invention is a method for manufacturing a conductive substrate in which a metal fine particle layer is laminated on at least one surface of a substrate in a mesh shape, and the metal fine particle layer is treated with an acid.

  The method for producing a conductive substrate of the present invention is excellent in transparency, conductivity, and productivity, and in particular, is a production method preferably used for making a conductive substrate using a thermoplastic resin film as a substrate. . The conductive substrate obtained by the method for manufacturing a conductive substrate of the present invention can be suitably used for an electromagnetic wave shield substrate used in a flat panel display such as a plasma display panel or a liquid crystal television.

  The size of the metal fine particles in the present invention is not particularly limited, but the number average particle diameter is preferably 0.001 to 5.0 μm. When the number average particle system of the metal fine particles exceeds this range, it may be difficult to form a metal layer in a network shape. Preferably it is 0.001-2.0 micrometers, More preferably, it is 0.002-1.5 micrometers, Most preferably, it is 0.002-0.2 micrometers. When the number average particle diameter is smaller than 0.001 μm, continuous contact between the metal fine particles is often interrupted, and as a result, sufficient conductivity may not be obtained. When the number average particle diameter is larger than 5.0 μm, the effect of increasing the conductivity in the treatment with the acid of the present invention described later cannot be obtained, and sufficient conductivity may not be obtained. The particle size distribution of the metal fine particles contained in the metal fine particle layer may be large or small, and the particle sizes may be irregular or uniform. 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.

  The metal fine particle layer in the present invention is a layer composed of the metal fine particles as described above, and in addition to the metal fine particles, various other additives such as a dispersant, a surfactant, a protective resin, an antioxidant, An inorganic component such as a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a pigment, a dye, organic or inorganic fine particles, a filler, an antistatic agent, and the like can be contained.

  In the present invention, a transparent and conductive substrate can be obtained by laminating metal fine particle layers in a network. The total light transmittance of the conductive substrate produced by the production method of the present invention is preferably 50% or more, more preferably 60% or more. If the light transmittance is less than 50%, there may be a problem in terms of transparency of the conductive substrate.

  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, as a solution of a compound capable of forming metal fine particles, a method of printing a solution of metal fine particles, a solution of metal oxide fine particles, a solution of an organic metal compound, or a mixture of two or more of these in a mesh pattern , A method of applying the above-described solution in a network, a method of physically cutting the metal fine particle layer into a network after laminating the above-described solution over the entire surface of the substrate, or performing a chemical etching process, Various methods can be selected, such as a method of creating a mesh-like groove on at least one surface of a substrate in advance by digging or embossing the substrate and filling the above-described solution therewith.

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

  In the present invention, it is preferable to use a solution in which at least one compound selected from compounds capable of forming metal fine particles, for example, metal fine particles, metal oxide fine particles, and organometallic compounds, is dispersed or dissolved in a solvent. 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 the compound capable of forming the metal fine particles is kneaded into the resin component and dispersed in the resin component, the effect of increasing the conductivity by the acid treatment of the present invention described later is used. Is not sufficiently exhibited, and excellent conductivity may not be obtained. 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 acid treatment of this invention is not fully expressed and the outstanding electroconductivity may not be obtained, it is unpreferable.

  Surprisingly, 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 treatment with the acid of the present invention is carried out with a low-concentration acid solution. It has been found that the effect of can be easily obtained. 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 mixing ratio of the metal fine particles and the resin component contained in the metal fine particle layer is preferably 900 parts by weight or more, more preferably 1900 parts by weight or more, further preferably 100 parts by weight of the resin component. It is 4900 parts by weight or more, and most preferably, it does not contain a resin component.

  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.

  The network structure may be a regular structure or an irregular (random) structure. When the conductive substrate manufactured by the manufacturing method of the present invention is used as, for example, an electromagnetic wave shielding substrate of a flat panel display, it is preferable to make the network structure random, since moire phenomenon does not occur. 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. Striped pattern that occurs when the images are overlapped. This is likely to occur when a halftone is reproduced using a halftone print as a manuscript. ”For flat panel displays, the striped pattern appears on the screen. The pattern appears. This is because when the mesh-like metal fine particle layer of the conductive substrate provided on the front surface of the display has a regular structure, the display body interacts with the regular grid-like partition walls that partition the pixels of each color of RGB. Moire phenomenon occurs. These are regularly arranged with respect to each other. In particular, the grid-like partition walls that partition the pixels cannot change the regular shape. Therefore, as one effective method for solving the moire phenomenon, the conductive barrier is used. And a method of randomizing the network structure of the conductive substrate. 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. Is. Therefore, the portion constituting the mesh, that is, the linear portion is also observed in an irregular state, that is, a random state. An example of a random network structure is shown in FIG. 1, but the present invention is not limited to this.

  In the present invention, the conductivity of the metal fine particle layer can be increased by treating the metal fine particle layer with an acid.

  The acid in the present invention 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.

  In the production process of the conductive substrate, the stage in which the metal fine particle layer is treated with an acid is not particularly limited, and the metal fine particle layer may be formed in a network on the substrate and then treated with an acid. The metal fine particles may be laminated on the entire surface of the substrate and then treated with an acid, and then the metal fine particle layer may be formed into a network by etching or the like. However, the metal fine particles are laminated on the substrate in a network. The method of treating with acid 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 an acid, 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 an acid, 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 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.

  A normal temperature is sufficient for the treatment temperature of the acid. If the treatment is performed at a high temperature, acid vapor is generated and the surrounding metal device is deteriorated. When a thermoplastic resin film is used as the base material, the base material is whitened and the transparency is impaired. Since there is a case, it 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 method of treating with an acid is not particularly limited. For example, the substrate in which a metal fine particle layer is laminated in an acid or an acid solution is immersed, or an acid or an acid solution is applied on the metal 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 are methods in which a substrate and an acid liquid are brought into direct contact, such as immersing a substrate in which a metal fine particle layer is laminated in an acid solution, or applying an acid or an acid solution on the metal 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 lower, or applying an acid or an acid solution on the metal fine particle layer. Is preferred.

  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 the case of a metal fine particle layer composed of metal fine particles having a number average particle diameter of 0.2 μm or less, the effect of the treatment with the acid of the present invention is sufficiently exhibited even with the above low concentration of acid. The number average particle diameter of the metal fine particles is particularly preferably 0.2 μm or less.

  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. 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. 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 metalized. 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.
Regarding the conductivity of the metal fine particle layer in the present invention, the surface specific resistance is preferably 30 Ω / □ or less. More preferably, it is 20 ohms / square or less, More preferably, it is 10 ohms / square or less. When the surface specific resistance is 30 Ω / □ or less, since the load due to the resistance is reduced when it is used as a conductive substrate, heat generation is suppressed, and it can be used at a low voltage. preferable. Further, for example, when used as a conductive substrate for an electromagnetic wave shielding substrate of a flat panel display such as a plasma display panel or a liquid crystal television, it is preferable because the electromagnetic wave shielding property is improved. The surface resistivity is measured, for example, after standing for 24 hours in a normal state (23 ° C., relative humidity 65%), and in that form in accordance with JIS-K-7194, Loresta-EP (manufactured by Mitsubishi Chemical Corporation). , Model No .: MCP-T360).

  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.

  In the present invention, a thermoplastic resin film can be used as the substrate because heat treatment for a long time at a high temperature is not required to increase the conductivity of the metal fine particle layer. When a board | substrate is a thermoplastic resin film, it is preferable at points, such as transparency, a softness | flexibility, and workability. 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. Those having at least one component selected from -naphthalate, ethylene-α, β-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate as the main component can be preferably used. . 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. 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 polyester described above 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 other than the substrate and the metal fine particle layer may be laminated on the conductive substrate of the present invention. 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 metal fine particle 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.

  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 solution is printed in a lattice shape on a biaxially stretched polyester film, and the silver fine particle layer is laminated in a lattice network structure. Thereafter, in order to treat the silver fine particle layer with an acid, the biaxially stretched polyester film is placed in 0.1N hydrochloric acid and left for several seconds to 60 minutes. Thereafter, the biaxially stretched polyester film is taken out, washed with water and dried.

  If the manufacturing method of the electroconductive board | substrate of this invention is used, the electroconductive board | substrate which has transparency and a high level electroconductivity can be obtained by the method excellent in productivity.

  Since the conductive substrate obtained by the method for manufacturing a conductive substrate of the present invention has transparency and a high level of conductivity, an electromagnetic wave shielding film used for flat panel displays such as plasma display panels and liquid crystal televisions. In addition, it can be suitably used for various conductive substrate applications such as circuit material applications and solar cell applications.

[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 of metal fine particles A solution in which metal fine particles are dispersed is dropped on a copper mesh and observed with a transmission electron microscope (H-7100FA type, manufactured by Hitachi, Ltd.). The number average particle size was determined. The particle diameter of 100 metal fine particles was measured, and the average value was defined as the number average particle diameter.

(2) Surface observation The metal fine particle layer of the conductive substrate was observed using a field emission scanning electron microscope (JSM-6700F type, manufactured by JEOL Ltd.), and the shape of the mesh and the width of the mesh portion were observed. Moreover, after cutting out the cross section of a conductive substrate, the cross section was similarly observed with the field emission scanning electron microscope, and the thickness of the mesh part was observed.

(3) Conductivity The conductivity of the metal fine particle layer of the conductive substrate was measured by the surface specific resistance. The surface resistivity was measured after standing for 24 hours in a normal state (23 ° C., relative humidity 65%), and in that atmosphere in accordance with JIS-K-7194, Loresta-EP (manufactured by Mitsubishi Chemical Corporation, model number : MCP-T360). The unit is Ω / □. In addition, this measuring device can measure below 1 × 10 ⁶ Ω / □. If the surface specific resistance is 30Ω / □ or less, the conductivity is good.

(4) Total light transmittance The total light transmittance was measured in the normal state (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. If the total light transmittance is 50% or more, the transparency is good. In the case of a conductive substrate in which a metal fine particle layer is laminated only on one side of the substrate, the conductive substrate was placed so that light enters from the surface side on which the metal fine particle layer was laminated.

(5) Moire-resistant phenomenon The anti-moire phenomenon is to hold a substrate in front of a flat panel display screen on which an image is projected so that the screen and the conductive substrate surface are approximately parallel, and the screen and the substrate surface are approximately parallel. While maintaining this state, the substrate was rotated 360 °, and it was evaluated by visually observing whether or not the moire phenomenon occurred during the rotation. Evaluation was performed using a 15-inch TFT liquid crystal monitor E152FPb manufactured by Dell as a flat panel display. In the case of a conductive substrate in which a metal fine particle layer was laminated only on one side of the substrate, the conductive substrate was held so that the surface side on which the metal fine particle layer was not laminated was opposed to the display screen.

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

(Metal fine particle layer forming solution 1)
Monoethanolamine was dropped into an aqueous solution of silver nitrate to obtain an aqueous solution of a silver alkanolamine complex (aqueous solution 1). Separately from this solution, an aqueous solution in which monoethanolamine was added to an aqueous solution in which quinone was dissolved as a reducing agent was prepared (aqueous solution 2). Next, the aqueous solution 1 and the aqueous solution 2 were simultaneously poured into a plastic container, and the silver alkanolamine complex was reduced to form silver fine particles. The mixture was filtered, washed with water, and dried to obtain silver fine particles. Furthermore, the silver fine particle solution was obtained by re-dissolving the silver fine particles in water. The number average particle system of the silver fine particles was 1.4 μm.

(Metal fine particle layer forming solution 2)
As the metal fine particle layer forming solution, XA-9053 manufactured by Fujikura Kasei Co., Ltd., which is a silver fine particle layer forming solution, was used. The number average particle diameter of the silver fine particles was 0.04 μm.

(Metal fine particle layer forming solution 3)
As the metal fine particle layer forming solution 3, CE102-2 manufactured by Cima NanoTech, which is a silver fine particle layer forming solution, was used. Example 1
On one side of a biaxially stretched polyethylene terephthalate film ("Lumirror" U94 manufactured by Toray Industries, Inc.), the metal fine particle layer forming solution 1 was printed by screen printing in a lattice shape having a line thickness of 3 μm, a line width of 50 μm, and a pitch of 300 μm. The printed metal fine particle forming solution 1 was dried at 120 ° C. for 1 minute to obtain a laminated substrate on which silver fine particle layers having a regular lattice network were laminated. In order to treat the silver fine particle layer of this multilayer substrate with an acid, the multilayer substrate was immersed in 0.1 N (0.1 mol / L) hydrochloric acid (N / 10-hydrochloric acid manufactured by Nacalai Tesque) for 2 minutes. Thereafter, the laminated substrate was taken out, washed with water, and then dried for 1 minute at 120 ° C. in order to remove moisture to obtain a conductive substrate. The surface resistivity of this conductive substrate was 8Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon occurred.

(Example 2)
Instead of 0.1N (0.1 mol / L) hydrochloric acid, 97% (about 18 mol / L) sulfuric acid (Ishizu Pharmaceutical Co., Ltd., sulfuric acid 97% reagent special grade) was used in the same manner as in Example 1. Thus, a conductive substrate was obtained. The surface resistivity of this conductive substrate was 10Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon occurred.

(Example 3)
Conductivity was obtained in the same manner as in Example 1 except that acetic acid (acetic acid reagent grade 1 manufactured by Ishizu Pharmaceutical Co., Ltd.) (about 17.5 mol / L) was used instead of 0.1 N (0.1 mol / L) hydrochloric acid. A substrate was obtained. The surface resistivity of this conductive substrate was 20Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon occurred.

Example 4
On one side of a biaxially stretched polyethylene terephthalate film ("Lumirror" U94 manufactured by Toray Industries, Inc.), the metal fine particle layer forming solution 1 was printed in a random network by screen printing. And the printed metal fine particle layer forming solution 1 was dried at 120 degreeC for 1 minute, and the laminated substrate which laminated | stacked the silver fine particle layer on the random mesh shape was obtained. The mesh had a line thickness of 3 μm, a line width of 50 μm, and a light transmittance of 70%. In order to treat the silver fine particle layer of this multilayer substrate with an acid, the multilayer substrate was immersed in 0.1 N (0.1 mol / L) hydrochloric acid (N / 10-hydrochloric acid manufactured by Nacalai Tesque) for 2 minutes. Thereafter, the laminated substrate was taken out, washed with water, and then dried for 1 minute at 120 ° C. in order to remove moisture to obtain a conductive substrate. The surface resistivity of this conductive substrate was 8Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Example 5)
Instead of 0.1N (0.1 mol / L) hydrochloric acid, 97% (about 18 mol / L) sulfuric acid (Ishizu Pharmaceutical Co., Ltd., sulfuric acid 97% reagent special grade) was used in the same manner as in Example 4. Thus, a conductive substrate was obtained. The surface resistivity of this conductive substrate was 10Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Example 6)
Conductivity was obtained in the same manner as in Example 4 except that acetic acid (acetic acid reagent grade 1 manufactured by Ishizu Pharmaceutical Co., Ltd.) (about 17.5 mol / L) was used instead of 0.1 N (0.1 mol / L) hydrochloric acid. A substrate was obtained. The surface resistivity of this conductive substrate was 20Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Example 7)
A conductive substrate was obtained in the same manner as in Example 4 except that the time for immersion in 0.1N (0.1 mol / L) hydrochloric acid was 15 seconds. The surface resistivity of this conductive substrate was 15Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Example 8)
A conductive substrate was obtained in the same manner as in Example 4 except that the time for immersion in 0.1N (0.1 mol / L) hydrochloric acid was 60 minutes. The surface resistivity of this conductive substrate was 28Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

Example 9
A conductive substrate was obtained in the same manner as in Example 4 except that the immersion time in 0.1N (0.1 mol / L) hydrochloric acid was 120 minutes. The surface resistivity of this conductive substrate was 40Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Example 10)

The metal fine particle layer forming solution 2 was printed in a random mesh pattern on one side of a biaxially stretched polyethylene terephthalate film (Lumirror (registered trademark) U94 manufactured by Toray Industries, Inc.) by screen printing. And the printed metal fine particle layer forming solution 2 was dried at 150 degreeC for 1 minute, and the laminated substrate which laminated | stacked the silver fine particle layer on the random mesh shape was obtained. The mesh had a line thickness of 2 μm and a line width of 50 μm.

Subsequently, in order to treat the silver fine particle layer of this film with an acid, the film was immersed in 1N (1 mol / L) hydrochloric acid (N / 1-hydrochloric acid manufactured by Nacalai Tesque) at 25 ° C. for 1 minute. Thereafter, the film was taken out, washed with water, and dried at 150 ° C. for 1 minute. This film had a surface specific resistance of 30Ω / □ and a total light transmittance of 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur. (Example 11)
The metal fine particle layer forming solution 2 is printed in a random network by screen printing, dried at 150 ° C. for 1 minute, and then dipped in acetone (special grade manufactured by Nacalai Tesque) for 30 seconds together with the film. The film was taken out and dried at 25 ° C. for 3 minutes. Thereafter, it was treated with an acid in the same manner as in Example 10, washed with water and dried. The surface specific resistance of this film was 5Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Example 12)

A conductive substrate was obtained in the same manner as in Example 11 except that it was treated with 5N (5 mol / L) hydrochloric acid (5N-hydrochloric acid, manufactured by Nacalai Tesque) at 25 ° C. The surface specific resistance of this film was 5Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur. (Example 13)

A conductive substrate was obtained in the same manner as in Example 11 except that it was treated with 5N (5 mol / L) hydrochloric acid (5N-hydrochloric acid, manufactured by Nacalai Tesque) at 40 ° C. The surface specific resistance of this film was 5Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur. (Example 14)

A conductive substrate was obtained in the same manner as in Example 11 except that it was treated with 2N (2 mol / L) hydrochloric acid (2N-hydrochloric acid manufactured by Nacalai Tesque) at 40 ° C. The surface specific resistance of this film was 5Ω / □, and the total light transmittance was 70%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur. (Example 15)
A conductive substrate was obtained in the same manner as in Example 11 except that it was immersed in 97% (about 18 mol / L) sulfuric acid at 50 ° C. (sulfuric acid 97% reagent special grade manufactured by Ishizu Pharmaceutical Co., Ltd.) for 5 seconds. The surface specific resistance of this film was 5Ω / □. In this example, the acid treatment caused whitening of the polyethylene terephthalate film, and the total light transmittance was 50%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Example 16)
A metal fine particle layer forming solution 3 is applied on the hydrophilic treatment layer of a biaxially stretched polyethylene terephthalate film that has been subjected to a hydrophilic treatment on one side and then allowed to pass for 10 minutes at 25 ° C., thereby laminating a silver fine particle layer in a random network shape. And then treated at 120 ° 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 film was immersed in 0.1N (0.1 mol / L) hydrochloric acid (N / 10-hydrochloric acid manufactured by Nacalai Tesque) at 25 ° C. for 2 minutes, the film was taken out, washed with water, and then washed at 120 ° C. with 1 Dried for minutes. The surface specific resistance of this film was 7Ω / □, and the total light transmittance was 80%. As a result of the evaluation of the anti-moire phenomenon, the moire phenomenon did not occur.

(Comparative Example 1)
On one side of a biaxially stretched polyethylene terephthalate film ("Lumirror" U94 manufactured by Toray Industries, Inc.), the metal fine particle layer forming solution 1 was printed by screen printing in a lattice shape having a line thickness of 3 μm, a line width of 50 μm, and a pitch of 300 μm. And the printed metal fine particle formation solution 1 was dried at 120 degreeC for 1 minute, and the laminated substrate which laminated | stacked the silver fine particle layer on the grid | lattice form was obtained. The surface resistivity of this laminated substrate was larger than the measurement limit (greater than 1 × 10 ⁶ Ω / □), and did not show conductivity.

In Examples 1 to 3, since a regular lattice network was formed, a moire phenomenon was expressed. On the other hand, in Examples 4 to 17, the moire phenomenon did not occur due to the random mesh.
In Examples 8 and 9, since the treatment time with acid was long, the surface specific resistance was slightly high. On the other hand, in Examples 4 and 7, a more preferable surface specific resistance was obtained by shortening the treatment time with the acid.
Compared with Example 10, in Example 11, the more preferable surface specific resistance was obtained by performing the process by the organic solvent (acetone) before performing the process by an acid.
In Example 15, the treatment temperature with the acid was high and the concentration of the acid solution was high, so the film was whitened and the total light transmittance was slightly lowered. On the other hand, in Examples 11 to 13, the treatment temperature with the acid was lowered, and the concentration of the acid solution was lowered, so that whitening did not occur and a more preferable total light transmittance was obtained.

  If the manufacturing method of the electroconductive board | substrate of this invention is used, the electroconductive board | substrate which has transparency and a high level electroconductivity can be obtained by the method excellent in productivity.

 The conductive substrate manufactured by the method for manufacturing a conductive substrate of the present invention has transparency and a high level of conductivity. Therefore, for example, it can be suitably used for flat panel displays such as plasma display panels and liquid crystal televisions.

An example of a metal fine particle layer having a random network structure.

Claims (11)

  A method for producing a conductive substrate, wherein a metal fine particle layer is laminated on at least one surface of a substrate in a mesh shape, wherein the metal fine particle layer is treated with an acid.   The process for producing a conductive substrate according to claim 1, wherein the metal fine particle layer is treated with an acid so that the surface specific resistance of the metal fine particle layer is 30 Ω / □ or less.   The method for producing a conductive substrate according to claim 1, wherein the substrate is a thermoplastic resin film.   The method for producing a conductive substrate according to claim 1, wherein the number average particle diameter of the metal fine particles contained in the metal fine particle layer is 0.2 μm or less.   The treatment according to any one of claims 1 to 4, wherein the treatment of the metal fine particle layer with an acid is to immerse the conductive substrate in an acid solution and / or to apply an acid solution to the conductive substrate. Of manufacturing a conductive substrate.   The method for producing a conductive substrate according to claim 1, wherein the treatment is performed with an acid solution at 40 ° C. or lower.   The conductive substrate according to claim 1, wherein the metal fine particle layer is laminated using 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. Manufacturing method.   The method for producing a conductive substrate according to claim 1, 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 1, wherein the metal fine particle layer is treated with an organic solvent and then treated with an acid.   The electroconductive board | substrate which can be obtained by the manufacturing method of the electroconductive board | substrate in any one of Claims 1-9.   The electroconductive board | substrate of Claim 10 whose total light transmittance is 50% or more.

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