JP2007115657A - Zinc oxide based transparent conductive substrate by ion plating method and manufacturing method thereof - Google Patents

Abstract

A zinc oxide-based transparent conductive substrate excellent in optical characteristics and heat resistance and a method for producing the same are provided.
On a heat-resistant acrylic resin transparent substrate obtained by copolymerizing 40 to 90% by mass of methyl methacrylate units, 5 to 20% by mass of maleic anhydride units, and 5 to 40% by mass of aromatic vinyl compound units. A zinc oxide-based transparent conductive substrate in which a zinc oxide-based transparent conductive film is directly formed.
[Selection] Figure 1

Description

  The present invention relates to a zinc oxide-based transparent conductive substrate suitable for a touch panel, an inorganic dispersion type EL lamp, a transparent electromagnetic wave shield, etc., and excellent in heat resistance and optical characteristics, 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 comparable to that of an ITO film. 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).
Further, as an attempt to directly adhere the ITO film and the acrylic base material, ethylene glycol diacrylate or the like is copolymerized with methyl methacrylate as a main component in the acrylic base material (see, for example, Patent Document 5).

JP-A-4-176857 Japanese Patent Laid-Open No. 2003-34860 JP-A-62-71111 JP-A-10-244629 Japanese Patent Laid-Open No. 62-173248

  An object of the present invention is to provide a zinc oxide-based transparent conductive substrate excellent in optical characteristics and heat resistance and a method for producing the same.

  As a result of earnest research to solve these problems, the change in birefringence due to external force, that is, the use of a heat-resistant acrylic transparent resin with a small photoelastic coefficient and a polar group on the substrate, There is no need to hard coat the acrylic transparent resin substrate, and by forming the transparent conductive film directly on the heat resistant acrylic resin transparent substrate, a zinc oxide transparent conductive substrate having excellent optical properties and heat resistance can be obtained. I found what I can do.

That is, the present invention is as follows.
(1) On a heat-resistant acrylic resin transparent substrate 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, A zinc oxide-based transparent conductive substrate in which a zinc oxide-based transparent conductive film is directly formed.
(2) 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 substrate according to (1), characterized by containing 15% by mass.

(3) The zinc oxide transparent conductive substrate according to (1) or (2), wherein the heat-resistant acrylic resin transparent substrate is a film or a sheet.
(4) A method for producing a zinc oxide-based transparent conductive substrate, comprising forming a zinc oxide-based transparent conductive film on a heat-resistant acrylic resin transparent substrate by an ion plating method.
(5) A plasma beam is supplied onto a heat-resistant acrylic resin transparent substrate using a pressure gradient type plasma gun, and the plasma beam is evaporated by a beam correction device provided around an evaporation material mainly composed of zinc oxide. The method for producing a zinc oxide-based transparent conductive substrate according to (4), wherein the zinc oxide-based transparent conductive film is formed by an ion plating method for concentrating on the material and evaporating and ionizing the evaporated material,
It is.

  Excellent optical properties and heat resistance by forming a zinc oxide-based transparent conductive film directly on a heat-resistant acrylic resin transparent substrate obtained by copolymerizing methyl methacrylate, maleic anhydride, and aromatic vinyl compounds A transparent conductive laminate can be obtained.

The present invention is described in further detail below.
The present invention relates to a zinc oxide-based transparent conductive film in which a zinc oxide-based transparent conductive film is directly formed on a heat-resistant acrylic resin transparent substrate obtained by copolymerizing methyl methacrylate, maleic anhydride, and an aromatic vinyl compound. Substrate.
The heat-resistant acrylic resin transparent substrate in the present invention is a copolymer comprising 40 to 90% by mass of methyl methacrylate units, 5 to 20% by mass of maleic anhydride units, and 5 to 40% by mass of aromatic vinyl compound units. The ratio of the aromatic vinyl compound unit to the maleic anhydride unit is preferably 1 to 3 times from the viewpoint of heat resistance and photoelastic coefficient. 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 coalescence 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. In the composition in this copolymer, unless the transparency is impaired, it is considered that the greater the amount of maleic anhydride units, the better the adhesion between the zinc oxide film and the heat-resistant acrylic resin transparent substrate.

  Here, the aromatic vinyl compound unit is a nuclear alkyl substitution such as styrene and o-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, o-ethylstyrene, p-ethylstyrene, p-tert-butylstyrene. Α-alkyl-substituted styrene such as styrene, α-methylstyrene, α-methyl-p-methylstyrene and the like. 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 heat-resistant 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 a heat-resistant 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. From this viewpoint, bulk polymerization and solution polymerization without using a suspending agent or an emulsifier are 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, azo compounds 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 Peroxides and azobis initiators that are soluble in the organic solvent to be used are preferable, and specifically, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, cyclohexane par. Oxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 1,1-azobis (1-cyclohexane) Xanthcarbonitrile), 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. As the heat-resistant acrylic resin, two or more types having different molecular weights, compositions, and the like can be used at the same time.

When producing the heat-resistant acrylic resin transparent substrate in the present invention, if necessary, dyes, pigments, heat stabilizers such as hindered phenols and phosphates, benzotriazoles, 2-hydroxybenzophenones, salicylic acid phenyl esters UV absorbers such as, phthalate ester, fatty acid ester, trimellitic acid ester, phosphate ester, polyester plasticizer, higher fatty acid, higher fatty acid ester, higher fatty acid mono, di, or triglyceride 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, phosphorus / bromine flame retardants, reflection 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, and reinforcing agent to prevent glare Acrylic rubber or the like 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 The method of doing is mentioned.

The heat-resistant acrylic resin transparent substrate of the present invention is preferably a film or a sheet.
The film / sheet of the heat-resistant 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 heat-resistant 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 film or sheet of the heat-resistant acrylic resin transparent substrate in the present invention must have transparency, and as a transparency index, it is preferable that the total light transmittance is 80% or more and the haze value is 5% or less. More preferably, the total light transmittance is 85% or more and the haze value is 2% or less.
The film or sheet of the heat-resistant acrylic resin transparent substrate in the present invention preferably has excellent optical isotropy, the retardation value is 30 nm or less, the variation of the slow axis is within 40 degrees, and more preferably the retardation value is 20 nm or less. It is preferable that the phase axis variation is 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 in the present invention needs to have heat resistance that can withstand the operation temperature when the zinc oxide-based transparent conductive film is formed on the surface thereof. As an index of the heat resistance, it is preferable that there is no warpage or deformation when left 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 film containing can be used.
The content of aluminum, gallium, boron, silicon, tin, indium, germanium, antimony, iridium, rhenium, cerium, zirconium, scandium, yttrium added to the zinc oxide film, when adding one of these, The atomic ratio of these materials to zinc oxide 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 total addition amount of the material to add with respect to zinc oxide 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 substrate 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 substrate, 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. Furthermore, the film thickness of the transparent conductive film of the present invention is desirably 20 to 500 nm depending on the application.

Although the sheet resistance value of a zinc oxide type transparent conductive substrate 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.
In the method for producing a zinc oxide-based transparent conductive substrate 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 can also be used. However, the most preferable method is based on the ion plating method.

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, the sputtering method, so that the damage to the substrate and the zinc oxide-based transparent conductive film deposited on the substrate when the particles collide is small. It is known that a film having good crystallinity 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.

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. Further, the influence can be suppressed by lowering 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.
Furthermore, you may laminate | stack the layer of arbitrary resin or an inorganic compound 1 layer or 2 layers or more as an outermost layer in the zinc oxide type transparent conductive laminated body of this invention. Such an outermost layer can have a role of a protective film, an antireflection film, a filter, or the like, or functions such as adjustment of the viewing angle of liquid crystal and anti-fogging.

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) Appearance evaluation of zinc oxide-based transparent conductive film When the surface of the zinc oxide-based transparent conductive substrate is magnified 800 times with a microscope and no cracks are found in the zinc oxide-based transparent conductive film, “○” (good) When the crack was recognized, it evaluated as "x" (defect).

(3) Measurement of change in sheet resistance with time 4-probe method (contact type): Evaluated according to JIS R 1637.
The sheet resistance value of the zinc oxide-based transparent conductive substrate was measured immediately after film formation and after standing in the laboratory for several days.
(4) Thermal oven test It left still for about 1 hour in the atmosphere of a temperature of 90 degreeC, and evaluated the curvature and deformation | transformation visually.

(5) Measurement of photoelastic coefficient A birefringence measuring apparatus 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) 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.

(B) 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.

(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 and Comparative Example 1]
(A) Heat-resistant acrylic resin, (b) Acrylic transparent resin substrate sheet (80 mm × 80 mm × 2 mmt) formed by extrusion molding of acrylic resin. After drying for a while, trace impurities such as moisture were removed.
(Deposition conditions)
Tablet: Zinc oxide sintered acrylic transparent resin substrate sheet added with 3% by mass of digallium trioxide Size: 80 mm × 80 mm × 2 mmt Flat acrylic transparent resin substrate sheet temperature: about 20 ° C. (room temperature)
Discharge voltage: 65V
Discharge current: 143A
Acrylic transparent resin substrate 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 directly formed on an acrylic transparent resin substrate as a transparent conductive film by an ion plating method to obtain a zinc oxide transparent conductive substrate. The film thickness of the transparent conductive film was adjusted to about 45 nm. The evaluation results of the zinc oxide based transparent conductive substrate are also shown in Table 1. Moreover, the microscope picture (800 times) for external appearance evaluation of a zinc oxide type transparent conductive film was shown in FIG.

  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 properties, transparent conductive film adhesion, heat resistance, and various functions (conductivity, electromagnetic shielding, near infrared absorption Zinc oxide-based transparent conductive substrate having 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 elements for solar cells Window electrodes, electrodes for input devices such as transparent touch panels, electromagnetic shielding films for electromagnetic shields, transparent radio wave absorbers, ultraviolet absorbers, and transparent semiconductor devices that can be used in combination with other metal films / metal oxide films it can.

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 (5)

  Directly zinc oxide on a heat-resistant acrylic resin transparent substrate obtained by copolymerizing 40 to 90% by mass of methyl methacrylate units, 5 to 20% by mass of maleic anhydride units and 5 to 40% by mass of aromatic vinyl compound units Zinc oxide-based transparent conductive substrate formed by forming a transparent transparent conductive film.   The zinc oxide-based transparent conductive film contains 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 substrate according to claim 1, which is contained.   The zinc oxide-based transparent conductive substrate according to claim 1 or 2, wherein the heat-resistant acrylic resin transparent substrate is a film or a sheet.   A method for producing a zinc oxide-based transparent conductive substrate, comprising: forming a zinc oxide-based transparent conductive film on a heat-resistant acrylic resin transparent substrate by an ion plating method.   A plasma beam is supplied on a heat-resistant acrylic resin transparent substrate using a pressure gradient plasma gun, and the plasma beam is concentrated on the evaporation material by a beam correction device provided around the evaporation material mainly composed of zinc oxide. The method of manufacturing a zinc oxide-based transparent conductive substrate according to claim 4, wherein the zinc oxide-based transparent conductive film is formed by an ion plating method in which the evaporation material is evaporated and ionized.

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