JP2007113110A - Zinc oxide transparent conductive multilayer body and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive multilayer body good in optical characteristics, adhesion with a zinc oxide transparent conductive film, stability of sheet resistance value and thermal stability by forming the zinc oxide transparent conductive film on an acrylic resin multilayer body whose surface hardness is enhanced by providing an acrylic transparent resin substrate in which the change of birefringence by external force, i.e., a photoelastic coefficient is low with a hard coat layer, and to provide a method for producing the same. <P>SOLUTION: The zinc oxide transparent conductive multilayer body is obtained by forming a zinc oxide transparent conductive film on an acrylic resin multilayer body in which one side or both sides of an acrylic resin transparent substrate are coated with one or more hard coat layers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a zinc oxide-based transparent conductive laminate suitable for touch panels, inorganic dispersion type EL lamps, transparent electromagnetic wave shields and the like, and excellent in optical characteristics and heat resistance, and a method for producing the same.

The transparent conductive film is widely known as a film having both visible light transmittance and electrical conductivity, and a typical example thereof is a tin-added indium oxide film (hereinafter referred to as “ITO film”). A laminate in which an ITO film is laminated on a transparent substrate is widely used as an electrode, a heating element by energization, an electromagnetic wave shielding material, or a translucent body. In recent years, the performance of zinc oxide (ZnO) transparent conductive films has been remarkably improved, and a specific resistance value, one of the main characteristics, can be obtained at a laboratory level that is inferior to that of ITO films. It has become like this. For this reason, there is a risk of depletion of resources, and expectation for a zinc oxide-based transparent conductive film is increasing as a next-generation transparent conductive film that can be replaced with an ITO film containing expensive indium or the like as a component.
However, the high performance of laboratory-level zinc oxide-based transparent conductive films has been achieved by precise film deposition techniques such as laser beam ablation and molecular beam epitaxy. The film formation speed and the film formation area are insufficient.

On the other hand, ITO film production on a transparent resin substrate is performed at a mass production level by a sputtering method or an ion plating method which is excellent in terms of film formation speed and film formation area, while polyethylene terephthalate or A zinc oxide-based transparent conductive film has been invented on polycarbonate (see, for example, Patent Document 1 and Patent Document 2).
As the base material of the transparent conductive film, glass has been mainly used so far. However, as demand and use increase, improvement in workability and productivity has been demanded. Therefore, in recent years, plastics that are lighter than glass and superior in workability and productivity have attracted attention, and polyethylene terephthalate, polycarbonate, cyclic olefin resins, and the like have been used. For electrode substrates used in liquid crystal displays, a polymer material molded body having a smaller birefringence is required even if the total light transmittance is the same, and in recent years, the liquid crystal display has become larger in size and the polymer optical material necessary for it. In order to reduce the birefringence distribution caused by the bias of the external force as the size of the molded product increases, a material having a small change in birefringence due to the external force, that is, a material having a small photoelastic coefficient is required.

Among them, acrylic resins are widely used because of their high transparency. When used as a base material, the acrylic resin base material and the ITO film are used to compensate for insufficient adhesion between the base material and the ITO film. It is known that a three-dimensionally cross-linked acrylic resin-based intermediate layer is interposed between them (for example, see Patent Document 3 and Patent Document 4). However, it is said that a transparent conductive substrate in which an ITO film is formed on an acrylic resin substrate is not stable because the sheet resistance value changes with time.
For electrode substrates used in liquid crystal displays, a polymer material molded body having a smaller birefringence is required even if the total light transmittance is the same, and in recent years, the liquid crystal display has become larger, and the polymer optics required for it. As the size of the molded material increases, a material having a small change in birefringence due to external force, that is, a material having a small photoelastic coefficient is required in order to reduce the distribution of birefringence caused by the bias of external force. An electrode substrate in which a silicon oxide layer is provided on polyarylate or polycarbonate as a transparent optically isotropic base sheet is known (see, for example, Patent Document 5). However, there is no example of a transparent conductive substrate in which a zinc oxide-based transparent conductive film is formed on an acrylic resin base material excellent in optical properties such as transparency and a small photoelastic coefficient.

JP-A-4-176857 Japanese Patent Laid-Open No. 2003-34860 JP-A-62-71111 JP-A-10-244629 Japanese Patent No. 3305022

  The present invention forms a zinc oxide-based transparent conductive film on an acrylic resin laminate having a surface hardness increased by having a hard coat layer on an acrylic transparent resin substrate having a small photoelastic coefficient, that is, a change in birefringence due to external force. Thus, it is an object of the present invention to provide a transparent conductive laminate having good optical properties, adhesion to a transparent conductive film, stability of sheet resistance and heat stability, and a method for producing the same.

As a result of intensive research to solve these problems, optical properties, transparent conductive films and the like can be obtained by forming a zinc oxide transparent conductive film on an acrylic resin laminate having a hard coat layer on an acrylic transparent resin substrate. It was found that a zinc oxide-based transparent conductive laminate excellent in adhesion, sheet resistance and heat resistance stability can be obtained.
That is, the present invention is as follows.
(1) A zinc oxide-based transparent conductive material in which a zinc oxide-based transparent conductive film is formed on an acrylic resin laminate in which one or both hard coat layers are coated on one or both surfaces of an acrylic resin transparent substrate. Laminated body.

(2) Heat resistance obtained by copolymerizing acrylic resin transparent substrate with 40 to 90% by weight of methyl methacrylate units, 5 to 20% by weight of maleic anhydride units, and 5 to 40% by weight of aromatic vinyl compound units The zinc oxide-based transparent conductive laminate according to (1), which is a resin. (3) The zinc oxide based transparent conductive laminate according to (1) or (2), wherein the acrylic resin transparent substrate is a film or a sheet.
(4) The zinc oxide based transparent conductive film is 0.05 to at least one selected from gallium, aluminum, boron, silicon, tin, indium, germanium, antimony, iridium, rhenium, cerium, zirconium, scandium, and yttrium. The zinc oxide-based transparent conductive laminate according to any one of (1) to (3), wherein the zinc oxide-based transparent conductive laminate is characterized by containing 15% by mass.

(5) The specific resistance of the zinc oxide-based transparent conductive laminate is 1.5 × 10 ⁻³ Ω · cm to 1.0 × 10 ⁻⁴ Ω · cm (1) to (4) ) The zinc oxide-based transparent conductive laminate according to any one of the above.
(6) A method for producing a zinc oxide-based transparent conductive laminate, comprising forming a zinc oxide-based transparent conductive film by an ion plating method on an acrylic resin laminate coated with a hard coat layer.
(7) A plasma beam is supplied onto the acrylic resin laminate coated with the hard coat layer using a pressure gradient type plasma gun, and the plasma is applied by a beam correction device provided around an evaporation material mainly composed of zinc oxide. The zinc oxide-based transparent conductive laminate according to (6), wherein the zinc oxide-based transparent conductive film is formed by an ion plating method in which a beam is concentrated on the evaporation material, and the evaporation material is evaporated and ionized. Body manufacturing method.

(8) A plasma beam is supplied onto an acrylic resin laminate coated with a hard coat layer using a pressure gradient plasma gun, and the plasma is applied by a beam correction device provided around an evaporation material mainly composed of zinc oxide. When a zinc oxide transparent conductive film is formed by an ion plating method in which a beam is concentrated on the evaporation material and the evaporation material is evaporated and ionized, the surface temperature of the acrylic resin laminate covering the hard coat layer is Before forming the zinc oxide-based transparent conductive film, the specific resistance of the zinc oxide-based transparent conductive laminate is 1.5 × 10 ⁻³ Ω · cm to 1.0 × 10 ^-4 Ω · cm, the method for producing a zinc oxide-based transparent conductive laminate according to (6) or (7),
It is.

  By forming a zinc oxide-based transparent conductive film on an acrylic resin laminate with increased surface hardness by having a hard coat layer on the acrylic-based transparent resin substrate, optical properties, adhesion to the transparent conductive film, sheet resistance A transparent conductive laminate having good value stability and heat resistance stability can be obtained.

The present invention is described in further detail below.
The present invention relates to a zinc oxide-based transparent conductive material in which a zinc oxide-based transparent conductive film is formed on an acrylic resin laminate in which one or both hard coat layers are coated on one surface or both surfaces of an acrylic resin transparent substrate. Is a conductive laminate.
The acrylic resin of the acrylic resin transparent substrate in the present invention is methacrylic acid ester such as cyclohexyl methacrylate, t-butyl cyclohexyl methacrylate, methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate. One or more monomers selected from acrylic acid esters such as 2-ethylhexyl acrylate are polymerized. Of these, a homopolymer of methyl methacrylate or a copolymer with other monomers is preferable.

  Examples of monomers copolymerizable with methyl methacrylate include other methallylic acid alkyl esters, acrylic acid alkyl esters, styrene and o-methyl styrene, p-methyl styrene, 2,4-dimethyl styrene, o-ethyl. Aromatic vinyl compounds such as styrene, p-ethyl styrene, p-tert-butyl styrene, etc., alkyl-substituted styrene, α-methyl styrene, α-alkyl-substituted styrene such as α-methyl-p-methyl styrene, acrylonitrile, Vinyl cyanides such as methacrylonitrile, maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide, unsaturated carboxylic acid anhydrides such as maleic anhydride, unsaturated acids such as acrylic acid, methacrylic acid and maleic acid, etc. Is mentioned.

  Among monomers copolymerizable with methyl methacrylate, alkyl acrylates are particularly excellent in thermal decomposition resistance, and methacrylic resins obtained by copolymerizing alkyl acrylates are fluid during molding. Is preferable. The amount of alkyl acrylates used when methyl acrylate is copolymerized with methyl methacrylate is preferably 0.1% by mass or more from the viewpoint of heat decomposability, and 15% from the viewpoint of heat resistance. % Or less is preferable. More preferably, it is 0.2-14 mass%, and it is especially preferable that it is 1-12 mass%. Among these alkyl acrylates, especially methyl acrylate and ethyl acrylate are remarkably most preferable even when they are copolymerized with a small amount of methyl methacrylate. The said monomer which can be copolymerized with methyl methacrylate can also be used 1 type or in combination of 2 or more types.

The heat-resistant acrylic resin preferably used in the present invention includes methacrylic acid ester and / or acrylic acid ester, styrene, o-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, o-ethylstyrene, p-ethyl. Aromatic vinyl compounds such as styrene, nuclear alkyl-substituted styrene such as p-tert-butylstyrene, α-alkyl-substituted styrene such as α-methylstyrene and α-methyl-p-methylstyrene, cyan such as acrylonitrile and methacrylonitrile Vinylimides, maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide, unsaturated carboxylic acid anhydrides such as maleic anhydride, copolymers with unsaturated acids such as acrylic acid, methacrylic acid and maleic acid, etc. Can be given. The methyl methacrylate unit in the copolymer is 40 to 90% by mass, the maleic anhydride unit is 5 to 20% by mass, the aromatic vinyl compound unit is 5 to 40% by mass, and the aromatic vinyl compound unit is based on the maleic anhydride unit. It is preferable from the point of heat resistance and a photoelastic coefficient that the ratio is 1-3 times. More preferably, the methyl methacrylate unit in the copolymer is 42 to 83% by mass, the maleic anhydride unit is 5 to 18% by mass, and the aromatic vinyl compound unit is 12 to 40% by mass. The methyl methacrylate unit in the polymer is 45 to 78% by mass, the maleic anhydride unit is 6 to 15% by mass, and the aromatic vinyl compound unit is 16 to 40% by mass. Preferred is methyl methacrylate-maleic anhydride-styrene copolymer, and this resin is excellent in heat resistance, moisture resistance, gas / water vapor barrier properties, optical properties, and solvent resistance.

  The acrylic resin preferably has a weight average molecular weight of 50,000 to 200,000. The weight average molecular weight is desirably 50,000 or more from the viewpoint of the strength of the molded product, and desirably 200,000 or less from the viewpoint of molding processability and fluidity. A more desirable range is 70,000 to 150,000. In the present invention, isotactic polymethacrylate and syndiotactic polymethacrylate can be used simultaneously. As a method for producing an acrylic resin, for example, generally used polymerization methods such as cast polymerization, bulk polymerization, suspension polymerization, solution polymerization, emulsion polymerization, and anionic polymerization can be used. It is preferable to avoid mixing of foreign substances as much as possible. From this viewpoint, bulk polymerization or solution polymerization without using a suspending agent or an emulsifier is desirable. When solution polymerization is performed, a solution prepared by dissolving a mixture of monomers in an aromatic hydrocarbon solvent such as toluene or ethylbenzene can be used. In the case of polymerizing by bulk polymerization, the polymerization can be started by irradiation with free radicals or ionizing radiation generated by heating, as is usually done.

  As the initiator used in the polymerization reaction, any initiator generally used in radical polymerization can be used. For example, an azo compound such as azobisisobutylnitrile, benzoyl peroxide, lauroyl peroxide, t-butylperoxy -When an organic peroxide such as 2-ethylhexanoate is used and the polymerization is carried out particularly at a high temperature of 90 ° C or higher, solution polymerization is common, so the 10-hour half-life temperature is 80 Preferred are peroxides, azobis initiators, etc. that are soluble in the organic solvent used at a temperature of not lower than ° C., specifically 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, cyclohexane per Oxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 1,1-azobis (1-cyclohex Sancarbonitrile), 2- (carbamoylazo) isobutyronitrile, and the like. These initiators are used in the range of 0.005 to 5% by mass. As the molecular weight regulator used as necessary in the polymerization reaction, any one used in general radical polymerization is used, for example, mercaptan compounds such as butyl mercaptan, octyl mercaptan, dodecyl mercaptan, 2-ethylhexyl thioglycolate and the like. It is mentioned as preferable. These molecular weight regulators are added in a concentration range such that the degree of polymerization is controlled within the above range. As a method for producing the heat-resistant acrylic resin, the method described in JP-B-63-1964 can be used. Two or more kinds of acrylic resins having different molecular weights, compositions, etc. can be used at the same time.

In order to produce an acrylic resin transparent substrate in the present invention, a dye, pigment, heat stabilizer such as hindered phenol or phosphate, benzotriazole, 2-hydroxybenzophenone, salicylic acid phenyl ester, if necessary UV absorbers such as phthalates, fatty esters, trimellitic esters, phosphate esters, polyesters, etc., higher fatty acids, higher fatty acid esters, higher fatty acid mono-, di- or triglycerides Mold release agents such as, higher fatty acid esters, polyolefin-based lubricants, polyether-based, polyether ester-based, polyether ester amide-based, alkyl sulfonate, alkylbenzene sulfonate, and other antistatic agents, phosphorus-based, Phosphorus / chlorine and phosphorus / bromine flame retardants and glare from reflected light Acrylic rubber obtained by multistage polymerization as an organic light diffusing agent such as methyl methacrylate / styrene copolymer beads, inorganic light diffusing agent such as barium sulfate, titanium oxide, calcium carbonate, talc, etc. Etc. may be used. When these additives are blended, it can be carried out by a known method. For example, a method in which an additive is dissolved in a monomer mixture in advance and polymerized, or an additive is dry-blended with a mixer or the like in a molten state, bead-like or pellet-like resin, and kneaded and granulated using an extruder And the like.

The hard coat layer in the present invention contributes to imparting properties such as scratch resistance, surface hardness, moisture resistance, heat resistance and solvent resistance to the acrylic resin transparent substrate.
Examples of the hard coat layer of the present invention include those obtained by curing a film made of a compound having at least two functional groups in the molecule. Examples of the functional group for forming the hard coat layer include a group having an unsaturated double bond such as a (meth) acryloyloxy group, a reactive substituent such as an epoxy group or a silanol group, and the like. . Among these, a group having an unsaturated double bond is preferably used because it can be easily cured by irradiation with an activation energy ray such as an ultraviolet ray or an electron beam. Examples of the compound having at least two groups having an unsaturated double bond in the molecule include polyfunctional acrylate compounds. Here, the polyfunctional acrylate compound refers to a compound having at least two acryloyloxy groups and / or methacryloyloxy groups in the molecule. Hereinafter, the acryloyloxy group and the methacryloyloxy group are collectively referred to as a (meth) acryloyloxy group.

Examples of the polyfunctional acrylate compound include the following.
Ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate, pentaglycerol Triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerin triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris (acryloyloxyethyl) isocyanurate Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane tetramethacrylate, pentaglycerol Trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerin trimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, tris (acrylo (Luoxyethyl) isocyanurate, a phosphazene (meth) acrylate compound in which a (meth) acryloyloxy group is introduced into the phosphazene ring of the phosphazene compound, a polyisocyanate compound having at least two isocyanate groups in the molecule and at least one (meta ) A urethane (meth) acrylate compound obtained by reacting an acryloyloxy group and a polyol compound having at least one hydroxyl group, a carboxylic acid halide having at least two carbonyl groups in the molecule and at least one (meta ) A polyester (meth) acrylate compound obtained by reacting with a polyol compound having an acryloyloxy group.
These compounds can be used alone or in admixture of two or more. Moreover, oligomers, such as a dimer of this each compound and a trimer, may be sufficient.

  The hard coat layer can be provided by a normal method, for example, by applying a hard coat agent to the surface of the resin base material to form a film and irradiating it with an activation energy ray. Examples of the coating method include a micro gravure coating method, a roll coating method, a dipping coating method, a spin coating method, a die coating method, a flow coating method, and a spray coating method. The thickness of the hard coat layer is preferably 0.5 to 50 μm, more preferably 1 to 20 μm, and more preferably 2 to 10 μm. When the thickness is 0.5 to 50 μm, the scratch resistance is good and cracks are less likely to occur.

  The hard coat layer of the present invention may be an antistatic hard coat layer. Examples of the antistatic hard coat layer include a hard coat layer in which conductive particles are dispersed and a hard coat layer containing a surfactant. Examples of the hard coat layer in which conductive particles are dispersed include a layer in which conductive particles are dispersed in a cured film obtained by curing a compound having at least two unsaturated double bonds. Examples of the conductive particles include oxides of metals such as tin, antimony, titanium, and indium, and composite oxides of these metals such as particles of indium tin composite oxide (ITO) and antimony-doped tin oxide. Can be mentioned. The particle diameter of the conductive particles is usually about 0.001 to 0.1 μm in terms of primary particle diameter. Within this range, transparency tends to be maintained.

In order to improve the abrasion resistance of the coating film and to reduce the volume shrinkage during curing, inorganic fine particles may be contained. As the inorganic fine particles, fine particles made of a metal oxide such as silica and titanium oxide are preferable. The content of the inorganic fine particles is preferably 20 to 60% by mass, and the average particle size of the inorganic fine particles is preferably 100 μm or less. Within this content range, the curling of the product film can be suppressed, and the occurrence of cracks due to poor stretchability and bending of the hard coat resin can also be reduced. The average particle size is preferably 100 nm or more.
In order to improve the hard coat property (scratch prevention property) of the antireflection layer, it is preferable to introduce a photosensitive group having photopolymerization reactivity on the surface of the inorganic fine particles. This photosensitive group is preferably a monofunctional or polyfunctional acrylate.
The surface of the hard coat layer in the present invention preferably has a pencil hardness of 4H or higher.

The acrylic resin transparent substrate is preferably a film or a sheet.
The film / sheet of the acrylic resin transparent substrate in the present invention is only a difference in thickness, the film means a thickness of 300 μm or less, and the sheet exceeds 300 μm. The thickness of the acrylic transparent resin substrate is preferably a film or sheet in the range of 0.01 to 10.0 mm. A film or sheet in the range of 0.01 to 10.0 mm is hard to be deformed during panel processing and easy to handle. Further, since deformation due to the load on the substrate is less likely to occur, a double image becomes prominent when the liquid crystal display element is assembled, and the display quality is unlikely to be impaired. A more preferred thickness is in the range of 0.1 to 5.0 mm.
The acrylic resin transparent substrate film or sheet must have transparency, and it is preferable that the total light transmittance is 80% or more and the haze value is 5% or less as an index of the transparency. More preferably, the total light transmittance is 85% or more and the haze value is 2% or less.

The film or sheet of the acrylic resin transparent substrate is preferably one having excellent optical isotropy, the retardation value is 30 nm or less, the variation of the slow axis is within 40 degrees, more preferably the retardation value is 20 nm or less, the variation of the slow axis. Is preferably within 20 degrees. Here, the retardation value is represented by a product Δn · d of a refractive index difference Δn of birefringence at a wavelength of 590 nm and a film thickness d measured using a known measuring apparatus.
The film or sheet of the acrylic resin transparent substrate needs to have heat resistance capable of withstanding the operation temperature when a metal vapor deposition film is formed on the surface by sputtering or vacuum vapor deposition. As an indicator of its heat resistance, when allowed to stand for about 30 minutes in an atmosphere at a temperature of 80 ° C.,
It is preferable that there is no warp or deformation. More preferably, there is no warping or deformation when left standing for about 1 hour in an atmosphere of 90 ° C.

The film or sheet of the heat-resistant acrylic resin transparent substrate in the present invention preferably has an absolute value of the photoelastic coefficient of less than 3.0 × 10 ⁻¹² / Pa. If the photoelastic coefficient is within this range, the change in birefringence due to stress is small, so that the contrast and the uniformity of the screen are excellent when used in a liquid crystal display device or the like.
The photoelastic coefficient is described in various documents (for example, Macromolecules).
2004, 37, 1062-1066), and is defined by the following equation.
| CR | = | Δn | / σR | Δn | = | n1-n2 |
(Where: | CR |: absolute value of photoelastic coefficient, σR: stretching stress, | Δn |: absolute value of birefringence, n1: refractive index in stretching direction, n2: refractive index perpendicular to stretching direction)
The closer the value of the photoelastic coefficient is to zero, the smaller the change in birefringence due to external force, which means that the change in birefringence designed for each application is small.

The material used for the zinc oxide-based transparent conductive film in the present invention is at least one selected from aluminum, gallium, boron, silicon, tin, indium, germanium, antimony, iridium, rhenium, cerium, zirconium, scandium, and yttrium. A zinc oxide-based transparent conductive film containing can be used.
Aluminum, gallium, boron, silicon, tin, indium, germanium, antimony, iridium, rhenium, cerium, zirconium, scandium, and yttrium are added to the zinc oxide transparent conductive film. In this case, the atomic ratio of these materials to zinc is preferably in the range of 0.05 to 15%. When added at such a ratio, the conductivity and transparency of the film can be maintained well. Moreover, when adding multiple types of these materials, the range of 15% or less of the whole addition amount of the material to add with respect to zinc is preferable. Among these materials, zinc oxide to which digallium trioxide is added is more suitable for the conductivity and transparency of the film.

The zinc oxide-based transparent conductive laminate preferably has a total light transmittance of 70% or more and a haze value of 10% or less. In this range, the transparency is good. More preferably, the total light transmittance is 80% or more and the haze value is 5% or less.
In the zinc oxide-based transparent conductive laminate, the thickness of the zinc oxide-based transparent conductive film is preferably in the range of 10 nm to 1000 nm. In this film thickness range, although it varies depending on the application, it is possible to obtain a continuous film in which flexibility is maintained.
Although the sheet resistance value of a zinc oxide type transparent conductive laminated body changes with uses, the thing of the range of 5-10000 ohms / square is preferable as an electroconductive material. More preferably, the range of 10 to 300Ω / □ is preferable.

The temperature of the substrate before forming the zinc oxide on the resin substrate is preferably a low temperature equal to or lower than the glass transition temperature, and the specific resistance value of the zinc oxide-based transparent conductive laminate is 1.5 × 10 ⁻³ Ω · The range of cm to 1.0 × 10 ⁻⁴ Ω · cm is preferable. Furthermore, the thing of the range of 1.0 * 10 < ^-3 > (omega | ohm) * cm-1.0 * 10 < ^-4 > (omega | ohm) * cm is preferable as an electroconductive material. In addition, when the temperature of the substrate before forming the zinc oxide is a low temperature below the glass transition temperature, the glass is the same as in the case of forming the zinc oxide-based transparent conductive film on the acrylic resin laminate coated with the hard coat layer. Even on the substrate, the value of the specific resistance value with respect to the film thickness of the zinc oxide-based transparent conductive film is almost the same. Furthermore, even when the temperature of the substrate before forming the zinc oxide-based transparent conductive film is a low temperature not higher than the glass transition temperature, the specific resistance value of the zinc oxide-based transparent conductive laminate can be minimized by the amount of oxygen introduced. .

In the method for producing a zinc oxide-based transparent conductive laminate formed by forming a zinc oxide-based transparent conductive film, the film forming method is not particularly limited, and a sputtering method, a vacuum deposition method, or a CVD method may be used. However, the most preferred method is by ion plating.
In the ion plating method, zinc oxide containing a dopant is disposed as a film forming material on a hearth or the like disposed in a film forming chamber, and the zinc oxide is irradiated with, for example, argon plasma to form zinc oxide. Is heated, evaporated, and each particle of zinc oxide that has passed through the plasma is deposited on a transparent resin film or sheet placed at a position facing the hearth or the like.
The ion plating method has less kinetic energy of particles than, for example, sputtering, so damage to the substrate and the zinc oxide film deposited on the substrate when the particles collide is small, and the crystallinity It is known that a good film can be obtained. Furthermore, it can be formed at high speed and is used industrially.

An ion plating apparatus suitable for carrying out a method for forming a zinc oxide-based transparent conductive film according to the present invention (hereinafter simply referred to as a film forming method) will be described with reference to FIG.
The ion plating apparatus 10 includes a vacuum vessel 12 that is a film forming chamber, a plasma gun (plasma beam generator) 14 that is a plasma source that supplies a plasma beam PB into the vacuum vessel 12, and a bottom portion in the vacuum vessel 12. An anode member 16 that is disposed and on which the plasma beam PB is incident is provided, and a transport mechanism 18 that appropriately moves a substrate holding member WH that holds a substrate W to be deposited above the anode member 16.

The plasma gun 14 is of a pressure gradient type, and its main body portion is provided on the side wall of the vacuum vessel 12. By adjusting the power supply to the cathode 14a, the intermediate electrodes 14b and 14c, the electromagnet coil 14d and the steering coil 14e of the plasma gun 14, the intensity and distribution state of the plasma beam PB supplied into the vacuum vessel 12 are controlled.
Reference numeral 20a indicates a carrier gas introduction path made of an inert gas such as Ar, which is the source of the plasma beam PB.

The anode member 16 includes a hearth 16a as a main anode for guiding the plasma beam PB downward, and an annular auxiliary anode 16b disposed around the hearth 16a.
The hearth 16a is controlled to an appropriate positive potential, and sucks the plasma beam PB emitted from the plasma gun 14 downward. In the hearth 16a, a through hole TH is formed at a central portion where the plasma beam PB is incident, and a vapor deposition material 22 is loaded in the through hole TH. The vapor deposition material 22 is a tablet formed into a columnar shape or a rod shape, and is heated and sublimated by an electric current from the plasma beam PB to generate a vapor deposition material. The hearth 16a has a structure for gradually raising the vapor deposition material 22, and the upper end of the vapor deposition material 22 always protrudes from the through hole TH of the hearth 16a by a certain amount.

The auxiliary anode 16b is composed of an annular container disposed concentrically around the hearth 16a, and a permanent magnet 24a and a coil 24b are accommodated in the container. The permanent magnet 24a and the coil 24b are magnetic field control members, and form a cusp-like magnetic field directly above the hearth 16a, whereby the direction of the plasma beam PB incident on the hearth 16a is controlled and corrected.
The transport mechanism 18 has a large number of rollers 18b arranged in the transport path 18a at equal intervals in the horizontal direction to support the substrate holding member WH, and rotates the rollers 18b to move the substrate holding member WH horizontally at a predetermined speed. And a drive device (not shown) to be moved. The substrate W is held by the substrate holding member WH. In this case, the substrate W may be fixedly disposed above the inside of the vacuum vessel 12 without providing the transport mechanism 18 for transporting the substrate W. The oxygen gas in the oxygen gas container 19 is supplied to the vacuum container 12 while the flow rate is adjusted to a predetermined amount by the mass flow meter 21.
Reference numeral 20b indicates a supply path for supplying an atmospheric gas other than oxygen, and reference numeral 20c indicates a supply path for supplying an inert gas such as Ar to the hearth 16a. Reference numeral 20d denotes an exhaust system.

An ion plating method using the ion plating apparatus 10 configured as described above will be described.
First, the vapor deposition material 22 is attached to the through hole TH of the hearth 16a disposed at the lower part of the vacuum vessel 12. On the other hand, the substrate W is disposed at an opposing position above the hearth 16a. Next, a process gas corresponding to the film forming conditions is introduced into the vacuum vessel 12. A DC voltage is applied between the cathode 14a of the plasma gun 14 and the hearth 16a. Then, a discharge is generated between the cathode 14a of the plasma gun 14 and the hearth 16a, thereby generating a plasma beam PB.

  The plasma beam PB reaches the hearth 16a by being guided by a magnetic field determined by the steering coil 14 and the permanent magnet 24a in the auxiliary anode 16b. At this time, since argon gas is supplied around the vapor deposition material 22, the plasma beam PB is easily attracted to the hearth 16a. The vapor deposition material 22 exposed to the plasma is gradually heated. When the vapor deposition material 22 is sufficiently heated, the vapor deposition material 22 sublimates and the vapor deposition material evaporates (emits). The vapor deposition material is ionized by the plasma beam PB, adheres (incides) to the substrate W, and is formed into a film. In addition, since the flight direction of the vapor deposition material can be controlled by controlling the magnetic field above the hearth 16a by the permanent magnet 24a and the coil 24b, the plasma activity distribution and the reactivity of the substrate W above the hearth 16a. The film formation speed distribution on the substrate W can be adjusted in accordance with the distribution, and a thin film having a uniform film quality can be obtained over a wide area.

In the method of manufacturing a zinc oxide-based transparent conductive film according to the present embodiment using the ion plating apparatus 10 described above, zinc oxide (ZnO) in which digallium trioxide (Ga 2 O 3) is added as a gallium source as the evaporation material 22 is used. And ion plating while adjusting the oxygen partial pressure of the vacuum vessel 12 to 0.012 Pa or less. Alternatively, a plurality of plasma beams may be prepared as necessary, and film formation may be continuously performed in a plurality of partitioned vacuum chambers.
According to this method for producing a zinc oxide-based transparent conductive film, a large-area zinc oxide-based transparent conductive film having a good balance between transparency and specific resistance and excellent film uniformity can be obtained at a high film formation rate. be able to.

  In particular, when a film is formed on a transparent resin film or sheet, the transparent resin film or sheet may be deformed because it is greatly affected by the plasma beam resistance and heat resistance. Here, when the transparent resin film or sheet is moved at a high speed of 1.0 m / min or more, the influence (plasma, heat) received from the plasma beam can be minimized and minimized. The influence can also be suppressed in reducing the discharge current value. Moreover, when forming a zinc oxide type transparent conductive film, an influence can be suppressed by making the surface temperature of the board | substrate W into low temperature below a glass transition temperature previously. Specifically, a temperature range of −20 ° C. to 50 ° C. is preferable.

In particular, it is most effective to increase the transport speed of the transparent resin film or sheet in order to shorten the influence (plasma, heat) received from the plasma beam. In this case, the discharge current value is high and the transparent resin to be formed is formed. Film formation is possible even when the distance between the film or sheet and the evaporation material is short, which is advantageous as an industrial process.
Furthermore, when forming a film on a transparent resin film, it is tensioned while controlling the unwinding speed and the winding speed in order to disperse and homogenize the damage received on the transparent resin film in the roll-to-roll film formation performed in the industry. It is preferable to form a film in a state where stress is applied, and there is a case where the film is formed in a state where a transparent resin film or sheet is heated in advance. Alternatively, the transparent resin film or sheet may be cooled during film formation.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The unit displayed in parts represents parts by mass.
<Evaluation method>
(1) Total light transmittance, haze It evaluated based on JISK6711.
(2) Measurement of in-plane retardation (Re) In-plane retardation (Re) at 23 ° C. was measured by a rotating analyzer method using a birefringence measuring apparatus RETS-100 manufactured by Otsuka Electronics Co., Ltd.

(3) Appearance evaluation of zinc oxide film The surface of the zinc oxide transparent conductive laminate was magnified 800 times with a microscope, and when no cracks were observed in the zinc oxide film, it was evaluated as “Good” (good). When it was recognized, it was evaluated as “x” (bad).
(4) Adhesion evaluation As a method for evaluating adhesion, a peel test is performed by bringing the adhesive surface of an adhesive tape (1.8 cm wide cello tape (registered trademark) made by Nichiban) into close contact with the zinc oxide film of the transparent conductive laminate. evaluate. The case where the zinc oxide film did not peel at all was indicated as “◯” (good), and the case where the entire surface was peeled off was indicated as “x” (defective).

(5) Measurement of change in sheet resistance with time 4-probe method (contact type): Evaluation was performed according to JIS R 1637.
The sheet resistance value of the zinc oxide-based transparent conductive laminate was measured immediately after film formation and after standing in a laboratory for several days.
(6) Durability test 1: Measurement of time-dependent change in sheet resistance after heat test After standing at 80 ° C. in a thermostatic chamber for 300 hours, the temperature was returned to room temperature, and then measured by the same method as in (5).

(7) Durability test 2: Measurement of time-dependent change in sheet resistance value after cold resistance test After standing at −20 ° C. freezer for 500 hours and returning to room temperature, measurement was performed in the same manner as in (5).
(8) Deformation Evaluation of Substrate 1: Thermal Oven Test The substrate was left to stand for about 30 minutes in an atmosphere at a temperature of 80 ° C., and the warpage and deformation were evaluated visually. When the transparent conductive laminate is not deformed or warped at all, “◯” (good), when it is slightly deformed / warped, “△” (possible), and when deformed / warped, “×”. (Bad) is displayed.
(9) Deformation evaluation of substrate 2: Thermal oven test The substrate was left to stand for about 1 hour in an atmosphere at a temperature of 90 ° C, and the warpage and deformation were evaluated visually. When the transparent conductive laminate is not deformed or warped at all, “◯” (good), when it is slightly deformed / warped, “△” (possible), and when deformed / warped, “×”. (Bad) is displayed.

(10) Measurement of photoelastic coefficient A birefringence measuring device described in detail in Macromolecules 2004, 37, 1062-1066 was used. A sheet piece tensioning device was placed in the laser beam path, and birefringence was measured while applying an extensional stress at 23 ° C. The strain rate during stretching was 20% / min (chuck interval: 30 mm, chuck moving speed: 6 mm / min), and the test piece width was 7 mm. From the relationship between birefringence (Δn) and tensile stress (σR), the photoelastic coefficient (CR) is calculated by finding the slope of the straight line in the linear region by least square approximation, and the absolute value (| CR |) of the photoelastic coefficient is obtained. It was. The smaller the absolute value of the slope is, the closer the photoelastic coefficient is to 0, indicating a preferable optical characteristic.
| CR | = | Δn | / σR | Δn | = | n1-n2 |
(CR: photoelastic coefficient, σR: stretching stress, Δn: birefringence, n1: refractive index in the stretching direction, n2: refractive index perpendicular to the stretching direction)

<Raw materials used>
(A) Acrylic resin 1,1-di-t-butylperoxy-3 was added to a monomer mixture consisting of 96.7 parts by weight of methyl methacrylate, 2.1 parts by weight of methyl acrylate, and 1 part by weight of xylene. , 3,3-trimethylcyclohexane 0.0294 parts by mass and n-octyl mercaptan 0.28 parts by mass are added and mixed uniformly. This solution is continuously supplied to a closed pressure-resistant reactor having an internal volume of 10 liters, polymerized with stirring at an average temperature of 130 ° C. and an average residence time of 2 hours, and then continuously sent to a reservoir connected to the reactor. The volatile matter is removed under a certain condition, and further transferred to the extruder in a molten state. The acrylic resin (methyl methacrylate / methyl acrylate) copolymer pellets used in the following examples Obtained. The resulting copolymer had a methyl acrylate content of 2.0%, a weight average molecular weight of 102,000, and a melt flow value at 230 ° C. and a load of 3.8 kg measured according to ASTM-D1238 was 2.0 g / min. Met.

(B) Heat-resistant acrylic resin A methyl methacrylate-maleic anhydride-styrene copolymer was obtained by the method described in JP-B 63-1964. The composition of the obtained copolymer was methyl methacrylate 74% by mass, maleic anhydride 10% by mass, styrene 16% by mass, copolymer melt flow rate value (ASTM-D1238; 230 ° C., 3.8 kg load). ) Was 1.6 g / 10 min.
(C) Creation of each resin transparent substrate A flat plate (80 mm × 80 mm × 2 mmt) was prepared for each resin using an F40 injection molding machine manufactured by Crockner. The molding temperature of each resin was as follows: heat-resistant acrylic resin: 270 ° C., acrylic resin: 260 ° C.

[Example 1]
(A) Acrylic resin injection-molded acrylic transparent resin substrate sheet (80 mm x 80 mm x 2 mmt) is immersed in a commercially available JPC hard coat solution TKH-36A, pulled up, and irradiated with ultraviolet rays. A hard coat layer was formed on the sheet surface. The film thickness of the hard coat layer was adjusted to about 4 μm.
The acrylic resin laminate covered with the hard coat layer was dried in advance by a vacuum dryer at 60 ° C. for about 1 hour before film formation to remove trace impurities such as moisture.

(Deposition conditions)
Tablet: Size of zinc oxide sintered acrylic resin laminate sheet to which 3% by mass of digallium trioxide was added: Temperature of 80 mm × 80 mm × 2 mmt flat acrylic resin laminate sheet: about 20 ° C. (room temperature)
Discharge voltage: 65V
Discharge current: 143A
Acrylic resin laminate sheet transport speed: 20 mm / sec
Pressure during film formation: 6.0 × 10 ⁻¹ Pa
Atmospheric gas conditions: Ar flow rate introduced / Oxygen flow rate introduced = 20/1
Zinc oxide was deposited on the acrylic resin laminate as a transparent conductive film by an ion plating method to obtain a zinc oxide-based transparent conductive laminate. The film thickness of the transparent conductive film was adjusted to about 45 nm. The specific resistance value of the zinc oxide-based transparent conductive laminate was 1.12 × 10 ⁻³ Ω · cm. The evaluation results of the zinc oxide-based transparent conductive laminate are also shown in Table 1. Furthermore, a micrograph (800 times) for appearance evaluation of the zinc oxide film is shown in FIG.

[Example 2]
(B) A zinc oxide-based transparent conductive laminate was obtained in the same manner as in Example 1 except that a heat-resistant acrylic resin was used. The specific resistance value of the zinc oxide-based transparent conductive laminate is 1.05 × 10 ⁻³ Ω · c
m. The evaluation results of the zinc oxide-based transparent conductive laminate are also shown in Table 1. Furthermore, a micrograph (800 times) for appearance evaluation of the zinc oxide film is shown in FIG.
[Example 3]
(B) Using a heat-resistant acrylic resin, film formation was repeated three times under the same film formation conditions as in Example 1 to obtain a zinc oxide-based transparent conductive laminate. The film thickness of the transparent conductive film was about 136 nm. The specific resistance value of the zinc oxide-based transparent conductive laminate was 6.21 × 10 ⁻⁴ Ω · cm.
[Comparative Example 1]
(A) An acrylic resin injection molded acrylic transparent resin substrate sheet (80 mm × 80 mm × 2 mmt) was directly formed under the same film formation conditions as in Example 1 to obtain a zinc oxide-based transparent conductive laminate. It was. The evaluation results of the zinc oxide-based transparent conductive laminate are also shown in Table 1.

  Zinc oxide-based transparent conductive substrate on which the zinc oxide-based transparent conductive film of the present invention is formed, that is, excellent in optical characteristics, transparent conductive film adhesion, heat resistance, and various functions (conductivity, electromagnetic shielding product, near infrared absorption Zinc oxide-based transparent conductive laminates with UV-cutting properties, etc., transparent electrodes such as liquid crystal displays, plasma displays, inorganic EL (electroluminescence) displays, organic EL displays, and electronic paper, and photoelectric conversion of solar cells Use in combination with other metal films / metal oxide films as device window electrodes, electrodes of input devices such as transparent touch panels, electromagnetic shielding films of electromagnetic shields, transparent radio wave absorbers, ultraviolet absorbers, and transparent semiconductor devices Can do.

It is a schematic explanatory drawing of the ion plating apparatus used in the Example of this invention. It is a figure of the microscope picture of the zinc oxide type transparent conductive film on the acrylic resin transparent substrate surface. It can be seen in the micrograph of Comparative Example 1 (magnification: 800 times) that a fine line indicating a crack is running.

Explanation of symbols

10 Ion plating device 12 Vacuum vessel PB Plasma beam 14 Plasma gun (plasma beam generator)
14a Plasma gun cathodes 14b, 14c Intermediate electrode 14d Electromagnetic coil 14e Steering coil 16 Anode member 16a Hearth 16b as main anode Ring auxiliary anode W Substrate WH Substrate holding member 18 Transport mechanism 18a Transport path 18b Roller 19 Oxygen gas container 20a Ar Carrier gas introduction path 20b made of inert gas such as supply path 20c for supplying atmospheric gas other than oxygen Supply path 20d for supplying inert gas such as Ar to Hearth Exhaust system TH Through port 21 Mass flow meter 22 Vapor deposition material 24a Permanent magnet 24b Coil

Claims (8)

  A zinc oxide-based transparent conductive laminate in which a zinc oxide-based transparent conductive film is formed on an acrylic resin laminate in which one or more hard coat layers are coated on one or both surfaces of an acrylic resin transparent substrate.   An acrylic resin transparent substrate is a heat-resistant resin obtained by copolymerizing methyl methacrylate units 40 to 90% by mass, maleic anhydride units 5 to 20% by mass, and aromatic vinyl compound units 5 to 40% by mass. The zinc oxide-based transparent conductive laminate according to claim 1.   The zinc oxide-based transparent conductive laminate according to claim 1 or 2, wherein the acrylic resin transparent substrate is a film or a sheet.   The zinc oxide-based transparent conductive film is 0.05 to 15% by mass of at least one selected from gallium, aluminum, boron, silicon, tin, indium, germanium, antimony, iridium, rhenium, cerium, zirconium, scandium, and yttrium. The zinc oxide-based transparent conductive laminate according to any one of claims 1 to 3, which is included. 5. The specific resistance of the zinc oxide-based transparent conductive laminate is 1.5 × 10 ⁻³ Ω · cm to 1.0 × 10 ⁻⁴ Ω · cm. 5. The zinc oxide-based transparent conductive laminate according to item 1.   A method of producing a zinc oxide-based transparent conductive laminate, comprising forming a zinc oxide-based transparent conductive film on an acrylic resin laminate coated with a hard coat layer by an ion plating method.   A plasma beam is supplied onto the acrylic resin laminate coated with the hard coat layer using a pressure gradient type plasma gun, and the plasma beam is applied to the plasma beam by a beam correction device provided around an evaporation material mainly composed of zinc oxide. The zinc oxide-based transparent conductive laminate according to claim 6, wherein the zinc oxide-based transparent conductive film is formed by an ion plating method in which the evaporation material is concentrated and evaporated to ionize the evaporated material. Method. A plasma beam is supplied onto the acrylic resin laminate coated with the hard coat layer using a pressure gradient type plasma gun, and the plasma beam is applied to the plasma beam by a beam correction device provided around an evaporation material mainly composed of zinc oxide. When the zinc oxide transparent conductive film is formed by an ion plating method in which the evaporation material is evaporated and ionized by concentrating on the evaporation material, the surface temperature of the acrylic resin laminate covering the hard coat layer is zinc oxide Before forming the transparent conductive film, the specific resistance of the zinc oxide-based transparent conductive laminate at a low temperature below the glass transition temperature is 1.5 × 10 ⁻³ Ω · cm to 1.0 × 10 ⁻⁴ Ω. The method for producing a zinc oxide-based transparent conductive laminate according to claim 6 or 7, characterized in that it is cm.

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