JP2015146244A - Transparent conductive film and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film with improved dimensional stability of the transparent conductive film, and a manufacturing method thereof.SOLUTION: A transparent conductive film 10 at least includes a transparent substrate 1 and a transparent conductive membrane 2 formed on one side of the transparent substrate 1. The transparent conductive membrane 2 is a crystallized indium tin oxide. A shrinkage ratio of the transparent conductive film 10 is 0.25% or less when the transparent conductive film 10 is heated at a condition of 150°C for an hour. Further, a shrinkage ratio of the transparent substrate 1 may be 0.50% or less when the transparent substrate 1 is heated at a condition of 150°C for an hour.

Description

  The present invention relates to a transparent conductive film used for an electrode of a touch panel or a flexible display, and a manufacturing method thereof.

  In recent years, transparent touch panels that allow input by simply touching a display screen with a finger or pressing the display screen with a pen have become widespread. The transparent conductive film used as an electrode of this touch panel generally has a configuration in which a conductive metal oxide film such as indium tin oxide (hereinafter sometimes referred to as “ITO”) is laminated on a glass or polymer film. ing. Particularly in recent years, transparent conductive films using polymer films such as polyethylene terephthalate have been used because they are excellent in flexibility and workability and are lightweight.

  The transparent conductive film in which ITO is formed on the polymer film cannot be sputtered at a high temperature due to the limitation of the heat-resistant temperature of the base material, so that the formed ITO becomes amorphous. Since amorphous ITO has a large resistance change before and after the heat resistance test and low transmittance, a heat treatment (annealing) for crystallization is generally performed. In the sputtering process in which the ITO layer of the transparent conductive film is formed, a method in which ITO is continuously formed while a transparent substrate is conveyed by a roll-to-roll method is generally used. If the subsequent crystallization process of the transparent conductive film can also be performed by a roll-to-roll method, a great merit can be obtained in terms of cost and productivity. However, since the heat treatment time is as long as several tens of minutes to about 2 hours, the amorphous transparent conductive film cut out of the sheet is often heat-treated.

  On the other hand, recently, a crystallization process in which heat treatment is performed by a roll-to-roll method under atmospheric pressure as in Patent Document 1 has been proposed. Thereby, it becomes possible to implement by a roll-to-roll method from the sputtering process and the crystallization process to the touch panel forming process which is a subsequent process, and a great merit is obtained in terms of cost and productivity.

JP 2012-199215 A

  However, the dimensional stability of the transparent conductive film is reduced by the heat treatment in the crystallization step, and thus it may be difficult to align the electrodes and wiring.

  This invention is made | formed in view of the subject of this prior art, The objective aims at providing the transparent conductive film which improved the dimensional stability of the transparent conductive film, and this manufacturing method.

  As a means for solving the above problems, one embodiment of the present invention is a transparent conductive film including at least a transparent substrate and a transparent conductive film formed on one surface of the transparent substrate. The transparent conductive film is crystallized indium tin oxide, and the transparent conductive film has a shrinkage of 0.25% or less when the transparent conductive film is heated at 150 ° C. for 1 hour. It is a transparent conductive film characterized by being.

  In one embodiment of the present invention, the shrinkage rate of the transparent substrate may be 0.50% or less when the transparent substrate is heated at 150 ° C. for 1 hour.

  Another embodiment of the present invention is a method for producing a transparent conductive film comprising at least a transparent substrate and a transparent conductive film formed on one surface of the transparent substrate, wherein the transparent group A film forming step of forming a transparent conductive film made of amorphous indium tin oxide on one surface of the material by a sputtering method, and the transparent substrate on which the transparent conductive film is formed at 120 ° C. or more And an annealing step of continuously heating at a temperature of 175 ° C. or lower. By passing through the annealing step, the shrinkage rate of the transparent conductive film when heated at 150 ° C. for 1 hour is set to 0. It is a manufacturing method of the transparent conductive film characterized by setting it as 25% or less.

  Moreover, in another aspect of the present invention, a pre-deposition annealing step of continuously heating the transparent substrate while transporting the transparent substrate into the chamber may be provided before the film formation step.

  In another aspect of the present invention, the heating temperature in the pre-deposition annealing step may be 80 ° C. or higher and 160 ° C. or lower.

  In another aspect of the present invention, the shrinkage rate of the transparent substrate may be 0.50% or less when heated at 150 ° C. for 1 hour through the pre-deposition annealing step. .

  In another aspect of the present invention, the time during which the transparent substrate is heated in the pre-deposition annealing step may be not less than 20 seconds and not more than 60 seconds.

In another aspect of the present invention, when the thickness of the transparent substrate is d ₀ [μm] and the width of the transparent substrate is w ₀ [m] in the annealing step before film formation, the transparent substrate May be represented by the following formula: T ₀ [N] when the roller is transported by the transport roller.
600 × d ₀ / w ₀ ≦ T ₀ ≦ 4800 × d ₀ / w ₀

  In another aspect of the present invention, in the annealing step, the time during which the transparent base material on which the transparent conductive film is formed is heated may be 2 min or more and 60 min or less.

In another aspect of the present invention, when the thickness of the transparent substrate is d ₁ [μm] and the width of the transparent substrate is w ₁ [m] in the annealing step, the transparent substrate is a transport roller. The tension T ₁ [N] at the time of being conveyed may be represented by the following formula.
600 × d ₁ / w ₁ ≦ T ₁ ≦ 2100 × d ₁ / w ₁

  ADVANTAGE OF THE INVENTION According to invention, the transparent conductive film which improved the dimensional stability of the transparent conductive film, and this manufacturing method can be provided.

It is sectional drawing which shows 1st embodiment of the transparent conductive film of this invention. It is sectional drawing which shows 2nd embodiment of the transparent conductive film of this invention. It is a front view of the apparatus for performing the annealing process (or annealing process) before film-forming of this invention. It is a flowchart which shows each process of 1st embodiment of the manufacturing method of the transparent conductive film of this invention. It is a flowchart which shows each process of 2nd embodiment of the manufacturing method of the transparent conductive film of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and modifications such as design changes can be made based on the knowledge of those skilled in the art, and such modifications have been added. Embodiments are also included in the scope of the present invention.

[Transparent conductive film]
<First embodiment>
First, the transparent conductive film of 1st embodiment is demonstrated. The transparent conductive film 10 of 1st embodiment is comprised from the transparent base material 1 and the transparent conductive film 2 formed in one surface of the transparent base material 1, as shown in FIG.

  When the transparent conductive film 10 is heated at 150 ° C. for 1 hour, the shrinkage rate of the transparent conductive film 10 is preferably 0.25% or less. When the shrinkage rate of the transparent conductive film 10 is in this range, the dimensional stability is good and the positional accuracy required when assembling as a touch panel can be obtained. When the shrinkage rate of the transparent conductive film 10 exceeds 0.25%, the dimensional stability is poor and the positional accuracy required when assembling as a touch panel cannot be obtained. In addition, the lower limit of the shrinkage rate of the transparent conductive film 10 is not particularly limited, but it is preferable to make the shrinkage rate as small as possible.

  The transparent substrate 1 is made of a plastic film. The plastic film has a refractive index in the range of 1.45 or more and 1.60 or less, has a sufficient strength in the film forming process of each layer described later and the processes after the film forming process, and has a good surface smoothness. If there is, it will not be specifically limited. Specific examples include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, polysulfone, polyarylate, cyclic polyolefin, polyimide, and triacetylrose. The thickness of the transparent substrate 1 is preferably about 10 μm or more and 200 μm or less in consideration of the thinning of the member and the flexibility of the substrate. In particular, when the touch panel is required to be optically isotropic, it is preferable to select a film having a low retardation such as a cycloolefin polymer, a cycloolefin copolymer, a polycarbonate, or triacetyl cellulose.

  When the transparent substrate 1 is heated at 150 ° C. for 1 hour, the shrinkage rate of the transparent substrate 1 is preferably 0.50% or less. When the shrinkage rate of the transparent substrate 1 is within this range, a transparent conductive film having a shrinkage rate of 0.25% or less can be obtained without excessive heating in an annealing step described later. When the shrinkage percentage of the transparent substrate 1 exceeds 0.50%, excessive heating is required during annealing in order to obtain a transparent conductive film of 0.25% or less. There is an adverse effect of occurrence and discoloration.

  Further, the shrinkage rate of the transparent base material 1 can be controlled to 0.50% or less by passing through a pre-deposition annealing process described later, but the shrinkage rate of the transparent base material 1 is 0.50% or less. If so, it is not necessary to perform pre-deposition annealing. In addition, although there is no restriction | limiting about the minimum of the shrinkage | contraction rate of the transparent base material 1, when a general base material is used, it will become 0.30% or more in many cases.

  The transparent conductive film 2 is made of indium tin oxide. What is necessary is just to select arbitrarily the content rate of the tin oxide doped by indium oxide according to the specification calculated | required by the device. When low resistance is required for the transparent conductive film 2, it is preferable that the content ratio of tin oxide is in the range of 2% by mass or more and 10% by mass or less.

  The transparent conductive film 2 is preferably made of crystallized indium tin oxide. The crystallized indium tin oxide is formed by forming an amorphous transparent conductive film on the transparent substrate 1 and then annealing (heating) to crystallize the transparent conductive film. .

The definition of “amorphous transparent conductive film” is that X-rays from the (222) plane of the transparent conductive film before and after heating when the transparent conductive film is heated at 150 ° C. under atmospheric pressure for 1 hour. Assume that the analysis strength is in the relationship of the following expression (1). Note that the X-ray analysis intensity before heating is I ₀ , and the X-ray analysis intensity after heating is I ₁ .
I ₀ / I ₁ ≦ 0.1 (1)

On the other hand, the definition of “crystallization of a transparent conductive film” is a case where one of the following two conditions is satisfied. The first condition is that the surface resistance value of the transparent conductive film before and after immersing the target transparent conductive film in hydrochloric acid having a concentration of 1 mass% for 30 minutes is in the relationship of the following formula (2). Suppose that there is. Here, R ₀ is a surface resistance value before being immersed in hydrochloric acid, and R ₁ is a surface resistance value after being immersed in hydrochloric acid.
_{R 1 / R 0 ≦ 1.4 ···} (2)

The second condition is that the X-ray analysis intensity from the (222) plane of the transparent conductive film is in the relationship of the following formula (3). Incidentally, X-rays analysis the intensity of the transparent conductive film of the transparent conductive film to be the I _2, at the time of a transparent conductive film not been annealed I ₃ was heated for 30 minutes at 0.99 ° C. at atmospheric pressure The X-ray analysis intensity of the transparent conductive film is used.
0.8 ≦ I ₃ / I ₂ (3)

  If the condition of “crystallization of transparent conductive film” is not satisfied, sufficient characteristics may not be obtained in terms of surface resistance value and heat resistance test resistance of the transparent conductive film.

  The thickness of the transparent conductive film 2 is not particularly limited, and may be appropriately adjusted according to the target characteristics. For example, it is preferably in the range of 10 nm to 50 nm, preferably in the range of 15 nm to 50 nm.

<Second Embodiment>
As shown in FIG. 2, the transparent conductive film of the second embodiment includes a first transparent thin film layer 3 provided between the transparent substrate 1 and the transparent conductive film 2, and the transparent substrate 1. The transparent conductive film 20 provided with the 2nd transparent thin film layer 4 provided in the other surface may be sufficient.

  It is preferable that the shrinkage rate of the transparent conductive film 20 when the transparent conductive film 20 is heated at 150 ° C. for 1 hour is 0.25% or less. When the shrinkage rate of the transparent conductive film 20 is within this range, the dimensional stability is good and the positional accuracy required when assembling as a touch panel can be obtained. When the shrinkage rate of the transparent conductive film 20 exceeds 0.25%, the positional accuracy required when assembling as a touch panel cannot be obtained. In addition, the lower limit of the shrinkage rate of the transparent conductive film 20 is not particularly limited, but it is preferable to make the shrinkage rate as small as possible.

  The first transparent thin film layer 3 has a function of adjusting the transmittance and hue of the transparent conductive film 20 and is a layer for improving visibility. When the 1st transparent thin film layer 3 consists of inorganic compounds, inorganic compounds, such as an oxide, sulfide, fluoride, nitride, can be used, for example. The first transparent thin film layer 3 made of such an inorganic compound has a refractive index different depending on its material (type of compound), and the first transparent thin film layer 3 having a different refractive index is formed with a specific film thickness. As a result, the optical characteristics can be adjusted. The first transparent thin film layer 3 is not limited to a single layer, and may be a plurality of layers according to the target optical characteristics.

  Examples of the inorganic compound having a low refractive index include magnesium oxide (1.6), silicon dioxide (1.5), magnesium fluoride (1.4), calcium fluoride (1.3 to 1.4), and fluorine. Examples thereof include cerium chloride (1.6) and aluminum fluoride (1.3). Examples of the inorganic compound having a high refractive index include titanium oxide (2.4), zirconium oxide (2.4), zinc sulfide (2.3), tantalum oxide (2.1), and zinc oxide (2. 1), indium oxide (2.0), niobium oxide (2.3), tantalum oxide (2.2), and the like. However, the numerical value in the parenthesis represents a refractive index.

  The thickness of the 1st transparent thin film layer 3 does not have limitation in particular, What is necessary is just to specify together with the kind of inorganic compound to be used according to the target optical characteristic. For example, a range of 10 nm to 100 nm is preferable.

  The second transparent thin film layer 4 is a layer for imparting mechanical strength to the transparent conductive film. Although the material which comprises the 2nd transparent thin film layer 4 is not specifically limited, Resin which has transparency, moderate hardness, and mechanical strength is preferable. Specifically, a photocurable resin such as a monomer or a crosslinkable oligomer having a tri- or higher functional acrylate as a main component that can be expected to be three-dimensionally cross-linked is preferable. The second transparent thin film layer 4 is preferably formed on the surface of at least one of the transparent substrates 2, and may be formed on both surfaces of the transparent substrate 2. However, as shown in FIG. 2, it is preferable that the second transparent thin film layer 4 is formed on the surface of the transparent substrate 1 where the first transparent thin film layer 3 is not provided.

  Trifunctional or higher acrylate monomers include trimethylolpropane triacrylate, isocyanuric acid EO-modified triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate Ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, polyester acrylate and the like are preferable. Particularly preferred are isocyanuric acid EO-modified triacrylate and polyester acrylate. These may be used alone or in combination of two or more. In addition to these tri- or higher functional acrylates, so-called acrylic resins such as epoxy acrylate, urethane acrylate, and polyol acrylate can be used in combination.

  As the crosslinkable oligomer, acrylic oligomers such as polyester (meth) acrylate, polyether (meth) acrylate, polyurethane (meth) acrylate, epoxy (meth) acrylate, and silicone (meth) acrylate are preferable. Specific examples include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bisphenol A type epoxy acrylate, polyurethane diacrylate, and cresol novolac type epoxy (meth) acrylate.

  The second transparent thin film layer 4 may additionally contain additives such as particles and a photopolymerization initiator.

  Examples of the particles to be added include organic or inorganic particles, but it is preferable to use organic particles in consideration of transparency. Examples of the organic particles include particles made of acrylic resin, polystyrene resin, polyester resin, polyolefin resin, polyamide resin, polycarbonate resin, polyurethane resin, silicone resin, and fluorine resin.

  The average particle diameter of the particles varies depending on the thickness of the second transparent thin film layer 4, but for reasons of appearance such as haze, the lower limit is 2 μm or more, more preferably 5 μm or more, and the upper limit is 30 μm or less, preferably 15 μm or less. Use one. Moreover, it is preferable that content of particle | grains is 0.5 mass% or more and 5 mass% or less with respect to resin for the same reason.

  When a photopolymerization initiator is added, radical generating photopolymerization initiators include benzoin and its alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyl methyl ketal, acetophenone, 2, 2 , -Dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, and other acetophenones, methylanthraquinone, 2-ethylanthraquinone, 2-amylanthraquinone and other anthraquinones, thioxanthone, 2,4-diethylthioxanthone, 2, 4 -Thioxanthones such as diisopropylthioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal, benzophenone, 4,4-bismeth Le benzophenones such aminobenzophenone and azo compounds, and the like. These can be used alone or as a mixture of two or more thereof, and further, tertiary amines such as triethanolamine and methyldiethanolamine, benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate, etc. It can be used in combination with a photoinitiator aid or the like.

  The addition amount of the photopolymerization initiator is 0.1% by mass or more and 5% by mass or less, and preferably 0.5% by mass or more and 3% by mass or less with respect to the main component resin. If it is less than the lower limit, curing of the second transparent thin film layer 4 becomes insufficient, which is not preferable. Moreover, when exceeding an upper limit, since yellowing of the 2nd transparent thin film layer 4 will be produced or a weather resistance will fall, it is unpreferable. The light used to cure the photocurable resin is ultraviolet rays, electron beams, or gamma rays, and in the case of electron beams or gamma rays, it is not always necessary to contain a photopolymerization initiator or a photoinitiator aid. As these radiation sources, high pressure mercury lamps, xenon lamps, metal halide lamps, accelerated electrons, and the like can be used.

  Although the thickness of the 2nd transparent thin film layer 4 is not specifically limited, The range of 0.5 micrometer or more and 15 micrometers or less is preferable. Further, the refractive index of the second transparent thin film layer 4 is more preferably the same as or similar to the refractive index of the transparent substrate 1, and is preferably about 1.45 or more and 1.75 or less.

  Unlike the transparent conductive film 10, the transparent conductive film 20 includes the first transparent thin film layer 3 and the second transparent thin film layer 4. For example, the transparent conductive film 10 includes the first transparent thin film layer. The structure which added only 3 and the structure which added only the 2nd transparent thin film layer 4 to the transparent conductive film 10 are also contained in the transparent conductive film of this invention.

  The transparent conductive film of this embodiment can be used suitably as a structural member of a touch panel.

[Method for producing transparent conductive film]
<First embodiment>
Next, the manufacturing method of a transparent conductive film is demonstrated. As shown in FIG. 4, the manufacturing method of the transparent conductive film of 1st embodiment is a transparent conductive film which is an amorphous indium tin oxide at least on one surface of a transparent base material by sputtering method. The film forming step (S1) to be formed and the transparent base material on which the transparent conductive film is formed are continuously heated at a temperature of 120 ° C. or higher and 175 ° C. or lower while being transferred into a chamber having an atmospheric pressure of 5 Pa or lower. Annealing step (S2). Moreover, you may provide the pre-deposition annealing process (S0) which heats the transparent base material before forming a transparent conductive film as a pre-process of a film-forming process.

(Annealing process before film formation)
In the step before the film forming step for forming the transparent conductive film, which will be described later, the transparent base material is preferably put into the annealing step before film formation in the form of a roll. By performing annealing on the transparent substrate before the film forming step, the residual stress of the transparent substrate is reduced, and there is an effect of suppressing a decrease in dimensional stability of the transparent conductive film due to the annealing step described later. All the annealing steps before film formation can be performed in a chamber by a roll-to-roll method.

  FIG. 3 is an example of a front view of the apparatus 30 for performing the pre-deposition annealing step, and conceptually illustrates the pre-deposition annealing step.

  In the apparatus of FIG. 3, the pre-deposition annealing process for the transparent substrate is all performed inside the chamber 31 by the roll-to-roll method. The chamber 31 includes an exhaust mechanism (not shown) for keeping the inside at an arbitrary pressure. A transparent base material is arrange | positioned at the unwinding part 32 with the roll form, and is wound up by the winding part 34 through the conveyance rollers 33a-33i. Heaters 35 and 36 are installed in the conveyance path, and the transparent substrate can be heated in a non-contact manner.

  In the annealing process before film formation, the roll-shaped transparent base material is unwound in the chamber 31, heated by the heaters 35 and 36 while being conveyed by the conveyance roller, and then again wound into the roll shape.

  The atmospheric pressure in the chamber 31 during the pre-deposition annealing step is preferably 5 Pa or less. By heating the chamber 31 in a low pressure state, the water contained in the transparent base material is reduced, and indium tin oxide, which is a transparent conductive film, is formed by sputtering from the transparent base material into the atmosphere. Thus, the amount of water discharged is reduced, the crystallization of the transparent conductive film proceeds, and the resistance value can be reduced. However, if the water in the atmosphere at the time of sputtering film formation can be sufficiently reduced by exhaust, the annealing step before film formation may be performed at atmospheric pressure.

  Heaters 35 and 36 for heating the transparent base material are installed in the transparent base material conveyance path. The heaters 35 and 36 are not particularly specified as long as the conveyed transparent substrate can be heated in a non-contact manner, and a halogen heater, a quartz tube heater, or the like is appropriately used. By measuring the temperature of the heated transparent base material with a temperature sensor and feeding it back to the heater control device, the temperature of the transparent base material being transported can be maintained at an arbitrary set value. The temperature sensor at this time is not particularly specified as long as the temperature of the conveyed substrate can be measured in a non-contact manner, but an infrared sensor such as an infrared thermocouple is preferable.

  It is preferable that the temperature of the transparent base material conveyed is maintained in the range of 80 ° C. or higher and 160 ° C. or lower. When the temperature is lower than 80 ° C., the effect of suppressing a decrease in the dimensional stability of the transparent conductive film due to an annealing process described later does not sufficiently appear. The dimensional stability of the transparent conductive film by an annealing process may deteriorate, or discoloration of a transparent substrate may occur.

Any of the transport rollers 33a to 33i for transporting the transparent base material is provided with a mechanism for controlling the transport speed to an arbitrary set value. It is preferable that the time during which the transparent substrate is heated can be expressed by the following formula (4) by controlling the conveyance speed. Note that the time during which the transparent substrate is heated is t ₀ [sec], the conveyance speed is V ₀ [m / min], and the length of the portion where the transparent substrate is heated by the heaters 35 and 36 is L ₀ [m]. And
20 ≦ t ₀ = L ₀ / V ₀ × 60 ≦ 60 (4)

If t ₀ is less than 20 sec, the effect of suppressing the decrease in dimensional stability of the transparent conductive film due to the annealing step described later does not sufficiently appear. If t ₀ exceeds 60 sec, wrinkles are formed on the transparent substrate being conveyed. In some cases, the dimensional stability of the transparent conductive film by the annealing process described later may deteriorate, or the transparent substrate may be discolored.

Any of the transport rollers 33a to 33i for transporting the transparent base material is provided with a mechanism for controlling the tension of the base material. The thickness of the transparent base material is d ₀ [μm], and the width of the transparent base material is set. When w ₀ [m] is set, the tension T ₀ [N] when the transparent base material is transported by the transport roller is represented by the following formula (5).
600 × d ₀ / w ₀ ≦ T ₀ ≦ 4800 × d ₀ / w ₀ (5)

When T is less than 600 × d ₀ / w ₀ , the transparent base material may come into contact with a part other than the transport roller in the apparatus during transport, and when T exceeds 4800 × d ₀ / w ₀ , it is heated and transported. There is a problem that the residual stress of the transparent substrate is increased, the transparent substrate being transported is wrinkled, and the effect of suppressing the decrease in dimensional stability of the transparent conductive film due to the annealing process described later is not sufficiently exhibited. is there.

  By passing through the pre-deposition annealing step described above, the shrinkage rate of the transparent substrate can be controlled to 0.50% or less when the transparent substrate is heated at 150 ° C. for 1 hour. When the shrinkage rate of the transparent substrate is within this range, a transparent conductive film having a shrinkage rate of 0.25% or less can be obtained without excessive heating in the annealing step described later. When the shrinkage rate of the transparent substrate exceeds 0.50%, excessive heating is required during annealing to obtain a transparent conductive film of 0.25% or less, and wrinkles of the transparent conductive film are generated. There is an adverse effect of causing discoloration. As a means for controlling the shrinkage rate of the transparent substrate to 0.50% or less, it is preferable to control the heating temperature in the annealing step before film formation. Specifically, it is preferable to keep the heating temperature in the range of 80 ° C. or higher and 160 ° C. or lower.

(Film formation process)
A transparent conductive film made of amorphous indium tin oxide is formed on one surface of the transparent substrate by a sputtering method. It is preferable to implement the manufacturing method which forms a transparent conductive film on a transparent base material by the roll-to-roll method excellent in cost and productivity. In addition, as a method for forming the transparent conductive film, it is preferable to form the transparent conductive film by a sputtering method that can stabilize the process and can densify the thin film.

(Annealing process)
As described above, the transparent base material on which the amorphous transparent conductive film is formed is put into the annealing process while being in the form of a roll. The annealing process is all performed by a roll-to-roll method in the chamber.

  The annealing process can be performed using the apparatus 30 for performing the above-described annealing process before film formation. Hereinafter, the annealing process will be described using the apparatus shown in FIG.

  In the apparatus of FIG. 3, the annealing process for the transparent substrate on which the amorphous transparent conductive film is formed is all performed inside the chamber 31. The chamber 31 includes an exhaust mechanism (not shown) for keeping the inside at an arbitrary pressure. The transparent base material on which the amorphous transparent conductive film is formed is disposed in the unwinding unit 32 in a roll form, and is wound up by the winding unit 34 through the transport rollers 33a to 33i. Heaters 35 and 36 are installed in the conveyance path, and the transparent base material on which the amorphous transparent conductive film is formed can be heated in a non-contact manner.

  In the annealing process, a transparent base material on which a roll-shaped amorphous transparent conductive film is formed is unwound in a chamber 31 under a low pressure, and is heated by heaters 35 and 36 while being conveyed by a conveying roller. After the crystalline transparent conductive film is crystallized, it is wound into a roll form again.

  The atmospheric pressure in the chamber 31 during the annealing step is preferably 5 Pa or less. By reducing the pressure in the chamber 31 to reduce the water in the atmosphere when the amorphous transparent conductive film is heated, crystallization proceeds and the resistance value of the transparent conductive film is reduced. be able to. If the atmospheric pressure in the chamber 31 exceeds 5 Pa, crystallization is hindered by the influence of water in the atmosphere, and the above formula (2) or formula (3) may not be satisfied.

  Heaters 35 and 36 for heating the transparent substrate on which the amorphous transparent conductive film is formed are installed on the transport path of the transparent substrate on which the amorphous transparent conductive film is formed. ing. The heaters 35 and 36 are not particularly specified as long as the transparent substrate on which the amorphous transparent conductive film to be transported is formed can be heated in a non-contact manner, and a halogen heater, a quartz tube heater, or the like is appropriately used. The temperature of the transparent substrate on which the heated amorphous transparent conductive film is formed is measured by a temperature sensor and fed back to the heater control device, so that the amorphous transparent conductive film being transported is The temperature of the formed transparent substrate is kept at an arbitrary set value. The temperature sensor at this time is not particularly specified as long as the temperature of the conveyed substrate can be measured in a non-contact manner, but an infrared sensor such as an infrared thermocouple is preferable.

  The temperature of the transparent base material on which the amorphous transparent conductive film to be conveyed is formed is preferably maintained in the range of 120 ° C. or higher and 175 ° C. or lower. When the temperature is lower than 120 ° C., the amorphous transparent conductive film is not crystallized. When the temperature is higher than 175 ° C., the transparent base material on which the amorphous transparent conductive film being transported is formed is wrinkled. In some cases, discoloration of the transparent substrate on which the amorphous transparent conductive film is formed may occur.

Any of the transport rollers 33a to 33i for transporting the transparent base material on which the amorphous transparent conductive film is formed has a mechanism for controlling the transport speed to an arbitrary set value. By controlling the conveyance speed, it is preferable that the time during which the transparent base material on which the amorphous transparent conductive film is formed is heated can be expressed by the following formula (6). Note that the time during which the transparent base material on which the amorphous transparent conductive film is formed is heated is t ₁ [min], the conveyance speed is V ₁ [m / min], and the amorphous transparent conductive material is heated with a heater. Let L ₁ [m] be the length of the heated portion of the transparent substrate on which the film is formed.
2 ≦ t ₁ = L ₁ / V ₁ ≦ 60 (6)

When t ₁ is less than 2 min, the amorphous transparent conductive film is not crystallized, and when t ₁ exceeds 60 min, the transparent substrate on which the amorphous transparent conductive film being transported is formed is formed. In some cases, the dimensional stability is lowered, or discoloration of the transparent substrate on which the amorphous transparent conductive film is formed may occur.

Any one of the transport rollers 33a to 33i for transporting the transparent base material on which the amorphous transparent conductive film is formed has a mechanism for controlling the tension of the base material. When the thickness of the transparent substrate on which the conductive film is formed is d ₁ [μm] and the width of the transparent substrate on which the amorphous transparent conductive film is formed is w ₁ [m] The tension T ₁ [N] when the transparent base material on which the crystalline transparent conductive film is formed is transported by the transport roller is represented by the following formula (7).
600 × d ₁ / w ₁ ≦ T ₁ ≦ 2100 × d ₁ / w ₁ (7)

When T ₁ is less than 600 × d ₁ / w ₁ , the transparent base material on which the amorphous transparent conductive film is formed may come into contact with a part other than the transport roller in the apparatus during transport. _{When 1} exceeds 2100 × d ₁ / w ₁ , the residual stress of the transparent base material on which the amorphous transparent conductive film being heated and transported is increased, and when heated in the touch panel process of the subsequent process This causes a problem that the heat shrinkage increases.

  By passing through the above annealing step, the shrinkage rate of the transparent conductive film when the transparent conductive film is heated at 150 ° C. for 1 hour can be controlled to 0.25% or less. By controlling the shrinkage rate of the transparent conductive film to 0.25% or less, it is possible to facilitate alignment of electrodes and wiring performed in a later step. If the shrinkage rate of the transparent conductive film exceeds 0.25%, the alignment of the transparent conductive film will be difficult when positioning the electrodes and wirings performed in the subsequent process, making alignment difficult. As a means for controlling the shrinkage rate of the transparent conductive film to 0.25% or less, it is preferable to control the heating temperature in the annealing step. Specifically, it is preferable to keep the heating temperature in the range of 120 ° C. or higher and 175 ° C. or lower.

  The above annealing process can also be applied to crystallization of indium composite oxide films other than indium tin oxide.

<Second Embodiment>
As described above, the transparent conductive film of the present invention is provided on the first transparent thin film layer 3 provided between the transparent substrate 1 and the transparent conductive film 2 and on the other surface of the transparent substrate 1. Moreover, the transparent conductive film 20 provided with the 2nd transparent thin film layer 4 may be sufficient. Hereinafter, a method for forming the first transparent thin film layer 3 and the second transparent thin film layer 4 will be described.

  The manufacturing method of the transparent conductive film of 2nd embodiment is the 2nd transparent thin film layer formation process (S10) which forms the 2nd transparent thin film layer 4 in one surface of a transparent base material, as shown in FIG. ), A first transparent thin film layer forming step (S11) for forming the first transparent thin film layer 3 on the other surface of the transparent substrate, and a transparent conductive film made of amorphous indium tin oxide is sputtered. The film forming step (S1) formed by the method and the transparent base material on which the transparent conductive film is formed are continuously conveyed at a temperature of 120 ° C. or higher and 175 ° C. or lower while being transferred into a chamber having an atmospheric pressure of 5 Pa or lower. And an annealing step (S2) for heating. Moreover, you may provide the pre-deposition annealing process (S0) which heats the transparent base material before a transparent conductive film is formed as a pre-process of a 1st transparent thin film layer formation process.

  The first transparent thin film layer 3 may be formed by any film forming method as long as the film thickness can be controlled, and the thin film dry coating method is particularly excellent. For this, a vacuum vapor deposition method, a physical vapor deposition method such as sputtering, or a chemical vapor deposition method such as a CVD method can be used. In particular, in order to form a thin film having a uniform film quality over a large area, a sputtering method in which the process is stable and the thin film becomes dense is preferable.

  The second transparent thin film layer 4 is formed by dissolving a resin as a main component in a solvent, a die coater, curtain flow coater, roll coater, reverse roll coater, gravure coater, knife coater, bar coater, spin coater, It forms with well-known coating methods, such as a micro gravure coater.

  The solvent is not particularly limited as long as it dissolves the main component resin and the like. Specifically, as a solvent, ethanol, isopropyl alcohol, isobutyl alcohol, benzene, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, n-butyl acetate, isoamyl acetate, ethyl lactate, methyl cellosolve, ethyl cellosolve, Examples include butyl cellosolve, methyl cellosolve acetate, and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination of two or more.

  As mentioned above, although the manufacturing method of the transparent conductive film of 2nd embodiment was demonstrated, this process is not limited to said process, Other processes, such as another layer being laminated | stacked on a transparent conductive film, are included. It may be provided.

  Next, specific examples of the present invention will be described.

[Evaluation method]
Evaluation in Examples and Comparative Examples was performed by the following method.
<Shrinkage rate>
(Measuring method)
The shrinkage rate s of the produced transparent conductive film is determined as follows. First, the distance d ₁ between any two points on the transparent conductive film is measured, and then the transparent conductive film is heated at 150 ° C. for 1 hour, cooled to room temperature, and then the distance d between the two points described above again. ₂ is measured and input into the following formula to calculate.
s = (d ₂ −d ₁ ) / d ₁
It should be noted that a general base material has different shrinkage rates in the MD direction and the TD direction, and the MD direction often has a higher shrinkage rate than the TD direction, and this paper describes the shrinkage rate in the MD direction.
<Dimensional stability>
(Measuring method)

  The dimensional stability of the transparent conductive film was evaluated as follows. Cut out two films in the MD direction from the roll of transparent conductive film at 300 mm square, attach the adhesive layer to the second transparent thin film layer surface of one of the cut out films, and the second transparent thin film layer surface of the other film And pasted together. Next, the alignment mark of the pattern is registered in the screen printer. This time, they were registered in a screen printer by screen printing on discarded film in advance. The print position does not change unless the position of the screen plate is changed. Next, a resist was applied to the indium tin oxide surface with a screen printer on one side of the bonded film, and cured by heat drying. The alignment mark displacement was measured when the surface on which the resist was not printed after setting at room temperature was set on a screen printer, and this was used as an index of dimensional stability. If the misalignment of the alignment mark is 50 μm or less, the touch panel process can pass and the dimension is stable.

[Example]
As a transparent substrate, PET (made by Toray Industries, Inc.) having a film thickness of 50 μm and a width of 1250 mm was used. And the transparent conductive film was produced through the following annealing processes before film-forming, a film-forming process, and an annealing process.

<Annealing process before film formation>
A pre-deposition annealing process for heating the transparent substrate was performed by a roll-to-roll method using the apparatus having the configuration shown in FIG. At this time, the pressure in the chamber was 5 Pa, and the heating temperature was 120 ° C. Further, the time t ₀ during which the transparent base material is heated was set to 30 seconds, the conveyance speed V ₀ was set to 20 m / min, and the length L _{0 of the} portion where the transparent base material was heated by the heaters 35 and 36 was set to 10 m. Further, the tension T ₀ when the transparent base material was transported by the transport roller was set to 50N.

<Film formation process>
Next, a transparent conductive film was formed on one surface of the transparent substrate by a DC magnetron sputtering method. At this time, ITO containing 8% by weight of tin oxide was used as a material for the transparent conductive film. The thickness of the transparent conductive film was 30 nm.

<Annealing process>
An annealing process for heating the transparent base material on which the amorphous transparent conductive film was formed was performed by a roll-to-roll method using the apparatus having the configuration shown in FIG. At this time, the atmospheric pressure in the chamber was set to 5 Pa, and the heating temperature was set to four conditions of 120 ° C., 135 ° C., 160 ° C., and 175 ° C. In addition, the Example according to each heating temperature was made into Examples 1-4, respectively. Further, the time t ₀ for heating the transparent base material was 2 min, the conveyance speed V ₀ was 5 m / min, and the length L _{0 of the} portion where the transparent base material was heated by the heaters 35 and 36 was 10 m. Further, the tension T ₀ when the transparent base material was transported by the transport roller was set to 50N.

[Comparative Examples 1 and 2]
In the annealing step of the example, the conditions were the same as those of the example except that the heating temperature was 110 ° C. and 190 ° C.

  The evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

  From Examples 1 to 4 and Comparative Examples 1 and 2 in Table 1, it can be seen that the higher the annealing heating temperature, the lower the shrinkage rate of the transparent conductive film and the smaller the alignment mark deviation. The heating temperature needs to be 120 ° C or higher where the alignment mark shift is 50 μm or less, which is necessary for the touch panel process, but at 190 ° C wrinkles and discoloration of the base material occur, and these do not occur It is necessary to make it 175 ° C. or lower. From the above, the heating temperature during annealing is 120 ° C. or higher and 175 ° C. or lower in order to obtain a transparent conductive film in which the base material is not wrinkled or discolored and the alignment mark deviation is 50 μm or less and the dimensional stability is good. It was confirmed that the shrinkage rate of the transparent conductive film needs to be 0.25% or less at that time.

DESCRIPTION OF SYMBOLS 1 ... Transparent base material 2 ... Transparent conductive film 3 ... 1st transparent thin film layer 4 ... 2nd transparent thin film layer 10, 20 ... Transparent conductive film 30 ... Composition Apparatus 31 for performing pre-annealing annealing process (or annealing process)... Chamber 32... Unwinding section 33a to 33i... Transport roller 34.

Claims (10)

A transparent conductive film comprising at least a transparent substrate and a transparent conductive film formed on one surface of the transparent substrate,
The transparent conductive film is crystallized indium tin oxide,
A transparent conductive film, wherein the transparent conductive film has a shrinkage of 0.25% or less when the transparent conductive film is heated at 150 ° C. for 1 hour.   The transparent conductive film according to claim 1, wherein the transparent base material has a shrinkage rate of 0.50% or less when the transparent base material is heated at 150 ° C. for 1 hour. At least a method for producing a transparent conductive film comprising a transparent substrate and a transparent conductive film formed on one surface of the transparent substrate,
A film forming step of forming a transparent conductive film made of amorphous indium tin oxide on one surface of the transparent substrate by a sputtering method;
An annealing step of continuously heating the transparent substrate on which the transparent conductive film is formed at a temperature of 120 ° C. or higher and 175 ° C. or lower;
With
By passing through the said annealing process, the shrinkage | contraction rate of the said transparent conductive film when heated on conditions of 150 degreeC and 1 hour shall be 0.25% or less, The manufacturing method of the transparent conductive film characterized by the above-mentioned.   The method for producing a transparent conductive film according to claim 3, further comprising a pre-deposition annealing step in which the transparent base material is continuously heated while being transported into the chamber before the film formation step. .   The method for producing a transparent conductive film according to claim 4, wherein the heating temperature in the pre-deposition annealing step is 80 ° C. or higher and 160 ° C. or lower.   6. The shrinkage rate of the transparent base material is 0.50% or less when heated at 150 ° C. for 1 hour by passing through the annealing step before film formation. The manufacturing method of the transparent conductive film of description.   The method for producing a transparent conductive film according to any one of claims 4 to 6, wherein, in the pre-deposition annealing step, the time during which the transparent substrate is heated is 20 sec or more and 60 sec or less. . Tension when the transparent substrate is transported by the transport roller when the thickness of the transparent substrate is d ₀ [μm] and the width of the transparent substrate is w ₀ [m] in the pre-deposition annealing step. T 0 _[N] are provided methods for producing the transparent conductive film according to any one of claims 4 to 7, characterized by being represented by the following formula.
600 × d ₀ / w ₀ ≦ T ₀ ≦ 4800 × d ₀ / w ₀   4. The method for producing a transparent conductive film according to claim 3, wherein, in the annealing step, the time during which the transparent base material on which the transparent conductive film is formed is heated is 2 minutes or more and 60 minutes or less. . In the annealing step, when the thickness of the transparent substrate is d ₁ [μm] and the width of the transparent substrate is w ₁ [m], the tension T ₁ [ N] is represented by a following formula, The manufacturing method of the transparent conductive film of Claim 9 characterized by the above-mentioned.
600 × d ₁ / w ₁ ≦ T ₁ ≦ 2100 × d ₁ / w ₁

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