JP2006139750A - Transparent conductive laminate and touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive laminate that highly satisfies the bending pen input durability for use in a touch panel by further improving its bendability. <P>SOLUTION: The transparent conductive laminate is formed by making a first transparent dielectric thin film, second transparent dielectric thin film and transparent electroconductive thin film overlie one surface of a transparent film base having thickness of 2-120 μm in this order, and by laminating a transparent substrate on the other surface of the film base through a transparent adhesive layer. The second dielectric thin film is an inorganic matter or a mixture of an organic matter and the inorganic matter. The conductive thin film has a crystal content of maximum particle size ≤300 nm and exceeding 50 area% in the crystal of materials forming the thin film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transparent conductive laminate having a film substrate such as a polyethylene terephthalate film and a touch panel using the same.

  Transparent and conductive thin films in the visible light range are used for new display methods such as liquid crystal displays and electroluminescence displays, transparent electrodes for touch panels, etc., as well as for preventing static charges and blocking electromagnetic waves in transparent articles. .

  Conventionally, as such a transparent conductive thin film, so-called conductive glass in which an indium oxide thin film is formed on glass is well known, but because the base material is glass, flexibility and workability are inferior, Depending on the application, it may not be used.

  Therefore, in recent years, transparent conductive thin films based on various plastic films such as polyethylene terephthalate film have advantages such as excellent impact resistance and light weight in addition to flexibility and workability. Is used.

  However, the transparent conductive thin film using such a film substrate has a problem of poor transparency due to the large light reflectance on the surface of the thin film, and also has poor scratch resistance and flex resistance of the conductive thin film, There was a problem that the electrical resistance increased or the wire was broken due to scratches during use.

  In particular, in the case of a conductive thin film for a touch panel, a pair of thin films facing each other through a spacer are in strong contact with each other at a pressing point from the one panel plate side. It is desired to have durability, that is, hitting characteristics, particularly pen input durability. However, the conventional transparent conductive thin film as described above is inferior in durability and has a problem that the life of the touch panel is shortened accordingly.

Thus, attempts have been made to improve the above-described problems of transparent conductive thin films using a film substrate. The applicant also applies a transparent first dielectric thin film, a transparent second dielectric thin film, and a transparent conductive thin film in this order on one surface of a transparent film substrate having a thickness of 2 to 120 μm. A transparent conductive laminate is proposed in which a transparent substrate is laminated on the other surface of the film substrate via a transparent adhesive layer (see Patent Documents 1 and 2).
JP 2002-316378 A (pages 2 to 4) JP 2002-326301 A (pages 2 to 5)

  In the above transparent conductive laminate, a transparent substrate is bonded to the other surface of a film substrate having a conductive thin film on one surface, while the first and second layers are interposed between the conductive thin film and the film substrate. Dielectric thin films are provided, and these thin films are selected so that the refractive index of each light of the film base and the conductive thin film has an appropriate relationship to improve transparency, and the scratch resistance and resistance of the conductive thin film are improved. Flexibility, hitting characteristics for touch panels, especially pen input durability are improved.

  However, further research by the present applicant has revealed that the above transparent conductive laminate may still be insufficient in terms of bending resistance. In other words, in the touch panel market, new applications such as games and smartphones have been expanding in recent years. At that time, the touch panel design is becoming narrower and used in a bent state near the frame. A high bending pen input durability that can be resisted is desired. In addition, it has been used under severer conditions, and high-load pen input durability that can withstand even when input is heavier than conventional input loads is desired. However, it has been found that the above transparent conductive laminate may not sufficiently satisfy this characteristic.

  In light of the above circumstances, the present invention further improves the previously proposed transparent conductive laminate, and is highly satisfied with the hitting characteristics for touch panels, particularly the bending pen input durability, by further improving the bending resistance. At the same time, an object of the present invention is to provide a transparent conductive laminate that satisfies a high load pen input durability and a touch panel using the same.

  In the process of earnest study for the above object, the inventors of the present invention have proposed the conductive thin film crystal grains provided on the film substrate via the first and second dielectric thin films in the transparent conductive laminate. We paid attention to the diameter. The crystal grain size depends on the material configuration of the conductive thin film itself (for example, in the case of an indium oxide thin film containing tin oxide, the increase or decrease of the tin oxide content), and the second dielectric thin film serving as the base of this thin film. It varies depending on the material configuration and further on the method of forming each thin film.

  Therefore, a large number of transparent conductive laminates having different crystal grain sizes of the conductive thin film were produced, and detailed experimental studies were repeated on the performance. As a result, there is a close relationship between the crystal grain size and grain size distribution and the bending resistance of the conductive thin film, and when the content of crystals having a particular grain size is regulated to a specific range, As a result of the improvement in bending resistance, it was found that not only the dot characteristics for a touch panel, particularly pen input durability, but also bending pen input durability can be greatly improved, and the present invention has been completed.

That is, the present invention provides a transparent first dielectric thin film, a transparent second dielectric thin film, and a transparent conductive thin film in this order on one surface of a transparent film substrate having a thickness of 2 to 120 μm. Laminate, and on the other side of the film substrate, a transparent substrate is bonded via a transparent adhesive layer,
The second dielectric thin film is an inorganic substance or a mixture of an organic substance and an inorganic substance,
The conductive thin film relates to a transparent conductive laminate, wherein the crystal content of a maximum particle size of 300 nm or less exceeds 50 area% in the crystal of the material forming the thin film.

  In the transparent conductive laminate, the transparent conductive thin film preferably has a crystal content with a maximum particle size of 200 nm or less in a crystal of a material forming the thin film exceeding 50 area%.

  In the transparent conductive laminate, the transparent conductive thin film preferably has a hardness of 1.5 GPa or more and an elastic modulus of 6 GPa or more.

  In the transparent conductive laminate, the conductive thin film can be formed of indium oxide containing tin oxide, and the content of tin oxide with respect to the total of indium oxide and tin oxide is 2 to 50% by weight. Is preferred. Furthermore, it is preferable that content of the tin oxide with respect to the sum total of an indium oxide and a tin oxide is 3 to 15 weight%.

In the transparent conductive laminate, the refractive index of light of the film substrate is n ₁ , the refractive index of light of the first dielectric thin film is n ₂ , the refractive index of light of the second dielectric thin film is n ₃ , When the refractive index of light of the conductive thin film is n ₄ ,
Their refractive indices satisfy the relationship n ₃ <n ₂ ≦ n ₁ <n ₄ ,
The thickness of the first dielectric thin film is 100 to 250 nm,
It is preferable that the thickness of the second dielectric thin film is 15 to 100 nm.

  In the transparent conductive laminate, the first dielectric thin film may be an organic material or a mixture of an organic material and an inorganic material.

  In the transparent conductive laminate, the second dielectric thin film is preferably an inorganic material formed by a vacuum deposition method.

  Further, the present invention provides a touch panel in which a pair of panel plates having conductive thin films are arranged to face each other through a spacer so that the conductive thin films are opposed to each other, and at least one of the panel plates has the above-described configuration. The present invention relates to a touch panel comprising a transparent conductive laminate.

  Thus, the transparent conductive laminate of the present invention relates to a conductive thin film provided on one surface of a film substrate via the first and second dielectric thin films, and the second dielectric thin film is made of an inorganic substance or Scratch resistance of the conductive thin film by forming the mixture of organic and inorganic materials and making the content of the crystal having a specific particle size within a specific range in the crystal of the material forming the conductive thin film At the same time, by further improving the bending resistance, the durability is further improved, and in addition to the hit point characteristics for the touch panel, particularly the pen input durability, the bending pen input durability is highly satisfied. In addition, the transparent conductive laminate of the present invention can satisfy various characteristics such as transparency by selecting the thickness and refractive index of each thin film to have an appropriate relationship.

  The material for the film substrate in the present invention is not particularly limited, and an appropriate material can be used. Specifically, polyester resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, polyvinyl chloride resins, polystyrene resins, polyvinyl resins Examples thereof include alcohol resins, polyarylate resins, polyphenylene sulfide resins, polyvinylidene chloride resins, and (meth) acrylic resins. Among these, polyester resins, polycarbonate resins, polyolefin resins and the like are particularly preferable.

  The thickness of these film base materials needs to be in the range of 2 to 120 μm, and particularly preferably in the range of 6 to 100 μm. If the thickness is less than 2 μm, the mechanical strength as a film substrate is insufficient, and the operation of continuously forming a thin film such as a dielectric thin film or a conductive thin film or a pressure-sensitive adhesive layer in the form of a roll is possible. It becomes difficult. On the other hand, if the thickness exceeds 120 μm, it becomes impossible to improve the scratch resistance of the conductive thin film based on the cushioning effect of the pressure-sensitive adhesive layer, which will be described later, and the dot characteristics for touch panels.

  Such a film substrate is subjected to an etching process such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation or undercoating on the surface in advance, and a first dielectric provided thereon. You may make it improve the adhesiveness with respect to the film base material of a body thin film. Further, before providing the first dielectric thin film, dust may be removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

  In the present invention, before the transparent conductive thin film is provided on one surface of the film base thus configured, the transparent first dielectric thin film and the transparent second dielectric are used as the foundation. The thin films are stacked in this order. The second dielectric thin film is formed of an inorganic material or a mixture of an organic material and an inorganic material. By laminating the base thin film in this way, the transparency and the scratch resistance and the flex resistance of the conductive thin film are improved, and good results are obtained in improving the spot characteristics for touch panels.

The materials of the first dielectric thin film and the second dielectric thin film include NaF (1.3), Na ₃ A1F ₆ (1.35), LiF (1.36), MgF ₂ (1.38), CaF ₂ (1.4), BaF ₂ (1.3), BaF ₂ (1.3), SiO ₂ (1.46), LaF ₃ (1.55), CeF (1.63), A1 ₂ O ₃ (1.63) and other inorganic substances (numbers in parentheses indicate the refractive index of light), acrylic resin, urethane resin, melamine resin, alkyd resin having a refractive index of light of about 1.4 to 1.6 And organic substances such as siloxane-based polymers, and mixtures of the inorganic substances and the organic substances.

  Among the materials described above, the material of the first dielectric thin film is desirably an organic material or a mixture of an organic material and an inorganic material. In particular, it is desirable to use a thermosetting resin made of a mixture of a melamine resin, an alkyd resin, and an organosilane condensate as the organic substance.

The material of the second dielectric thin film is an inorganic material or a mixture of an organic material and an inorganic material. In particular, SiO ₂ , MgF ₂ , A1 ₂ O ₃ or the like is preferably used as the inorganic substance.

  The first dielectric thin film and the second dielectric thin film can be formed by using the above materials by a vacuum deposition method, a sputtering method, an ion plating method, a coating method, or the like. In particular, as a method for forming the second dielectric thin film, a vacuum deposition method is preferable. If a transparent conductive thin film is formed on the second dielectric thin film formed by this method, the crystal constituting the transparent conductive thin film is formed. The particle size distribution can be easily within the preferred range. Examples of the heating method of the film forming material in the vacuum deposition method include a heat beam heating method and a resistance heating method.

  The first dielectric thin film has a thickness of 100 to 250 nm, preferably 130 to 200 nm. The second dielectric thin film may have a thickness of 15 to 100 nm, preferably 20 to 60 nm. By setting the thicknesses of the first and second dielectric thin films within the above ranges, it is easy to achieve characteristics such as transparency, scratch resistance, and bending resistance.

  In the present invention, after laminating the first and second dielectric thin films to be the base thin film on one surface of the film base material in this way, a transparent conductive thin film is provided thereon. The conductive thin film can be formed by the same method as in the first and second dielectric thin films. The thin film material to be used is not particularly limited, and for example, indium oxide containing tin oxide, tin oxide containing antimony, or the like is preferably used. In particular, indium oxide containing tin oxide is preferable.

The conductive thin film has a thickness of usually 10 nm or more, preferably 10 to 300 nm. If the thickness is less than 10 nm, it is difficult to form a continuous film having good electrical conductivity with a surface electrical resistance of 10 ³ Ω / □ or less.

  In the present invention, the conductive thin film formed as described above is formed of crystals, and the content of crystals having a maximum grain size of 300 nm or less exceeds 50 area% in the crystal of the material forming the thin film. So that it is controlled. The maximum grain size and distribution of the crystal are determined by observing the surface of the conductive thin film with a field emission transmission electron microscope (FE-TEM). The maximum crystal grain size is the largest diagonal or diameter in each observed polygonal or oval region. In addition, the content of the crystal having the maximum grain size is specifically the area occupied by the crystal of each grain size per unit area (1.5 μm × 1.5 μm) in the electron microscope image.

  In the conductive thin film, it is preferable that the crystal of the material forming the thin film further has a crystal content of a maximum particle size of 200 nm or less exceeding 50 area%. Furthermore, it is preferable that the crystal content in the range of the maximum particle size of 100 nm or less exceeds 50 area%. The crystal content is preferably 70 area% or more, and more preferably 80 area% or more. It has been found that by controlling the crystals in the conductive thin film in this way, the bending resistance can be further improved, the occurrence of cracks during bending can be suppressed, and the bending pen input durability for touch panels can be greatly improved. It was done. In addition, if the crystal grain size of the conductive thin film becomes too small, there will be a portion similar to the amorphous state in the conductive thin film, and the reliability and pen durability will decrease, so the crystal grain size will become extremely small. It is desirable not to be too much. From this viewpoint, the maximum crystal grain size is preferably 10 nm or more, and more preferably 30 nm or more.

  In addition, it is preferable that the material for forming the conductive thin film does not exceed the maximum crystal grain size of 300 nm. Furthermore, when the distribution of the maximum grain size of the crystal of the material forming the conductive thin film is divided into, for example, 100 nm or less, 100 to 200 nm, 200 to 300 nm, the crystals are concentrated in each distribution width. Instead, it is preferable to have at least two distribution widths from the viewpoint of balance of durability. Each of the at least two distribution widths preferably has a crystal content of at least 5 area%. In particular, it is preferable to have a crystal content of at least 5 area% in a distribution width of 100 nm or less and a distribution width of more than 100 to 200 nm. Most preferably, the crystal content with a distribution width of 100 nm or less exceeds 50 area%, further 70 area% or more, further 80 area% or more, and the remaining crystals exist in a distribution width of more than 100 to 200 nm. The case is preferred. The average grain size of the maximum grain size of the crystal of the material forming the conductive thin film is preferably 50 to 250 nm, more preferably 60 to 150 nm, and even more preferably 70 to 100 nm.

  In order to regulate the crystal grain size and grain size distribution of the conductive thin film as described above, the material configuration of the conductive thin film and the method of forming the thin film may be appropriately selected. For example, when the conductive thin film is formed of indium oxide (ITO) containing tin oxide, it is possible to increase the content ratio of crystals having a small particle size by increasing the tin oxide content in ITO. it can. The tin oxide content in ITO (content of tin oxide relative to the sum of indium oxide and tin oxide) is preferably 2 to 50% by weight, more preferably 3 to 15% by weight, and particularly 3 to 10% by weight.

The crystal grain size and grain size distribution of the conductive thin film can also be regulated by selecting the material configuration of the first and second dielectric thin films that form the base of this thin film and the method of forming the same. is there. For example, when a SiO ₂ thin film is formed as the second dielectric thin film, a crystal having a smaller particle size in the conductive thin film is formed by the vacuum evaporation method by electron beam heating than by the silica coating method. The content of can be increased.

In the present invention, the refractive index of light of the film substrate is usually about 1.4 to 1.7, and the refractive index of light of the conductive thin film is usually about 2. The refractive index of light of the film substrate is n ₁ , the refractive index of light of the first dielectric thin film is n ₂ , the refractive index of light of the second dielectric thin film is n ₃ , and the refractive index of light of the conductive thin film. the when the n _4, their refractive index _{n 3 <n 2 ≦ n 1} < desirably satisfy the n ₄ relationships. The first dielectric thin film and the second dielectric thin film satisfy the above-described relationship of the refractive index of light, that is, the refractive index n _{2 of} the first dielectric thin film has a _second refractive index n ₂ . An appropriate material is selected from the above materials so that it is larger than the refractive index n ₃ of the light of the dielectric thin film and equal to or less than the refractive index n ₁ of the light of the film substrate. desirable.

  In the present invention, the transparent substrate is provided on the other surface of the film base material provided with the transparent conductive thin film on the one surface through the first and second dielectric thin films as described above. Paste together. For this bonding, the above-mentioned pressure-sensitive adhesive layer may be provided on the transparent substrate, and the film base material may be bonded to this, or conversely, the above-mentioned pressure-sensitive adhesive layer is provided on the film base material. In addition, a transparent substrate may be bonded to this. In the latter method, the pressure-sensitive adhesive layer can be formed continuously with the film substrate as a roll, which is more advantageous in terms of productivity.

The pressure-sensitive adhesive layer only needs to have transparency, and for example, an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or the like is used. The pressure-sensitive adhesive layer has a function of improving the scratch resistance of the conductive thin film provided on one surface of the film base material and the hitting characteristics for a touch panel by the cushion effect after the transparent substrate is bonded. In order to perform this function better, it is desirable to set the elastic modulus of the pressure-sensitive adhesive layer in the range of 1 to 100 N / cm ² and the thickness in the range of 1 μm or more, usually 5 to 100 μm.

When the elastic modulus of the pressure-sensitive adhesive layer is less than 1 N / cm ² , the pressure-sensitive adhesive layer becomes inelastic, so that it is easily deformed by pressurization, causing irregularities in the film substrate and thus the conductive thin film, and the processed cut surface. The adhesive is likely to protrude from the surface, and further, the effect of improving the scratch resistance of the conductive thin film and the dot characteristics as a touch panel is reduced. On the other hand, if it exceeds 100 N / cm ² , the pressure-sensitive adhesive layer becomes hard and the cushioning effect cannot be expected, and the scratch resistance of the conductive thin film and the dot characteristics as a touch panel cannot be improved.

  When the thickness of the pressure-sensitive adhesive layer is less than 1 μm, the cushioning effect cannot be expected, so that it is not possible to expect the scratch resistance of the conductive thin film and the improvement of the dot characteristics as a touch panel. On the other hand, if the pressure-sensitive adhesive layer is too thick, the transparency is impaired, and it is difficult to obtain good results in terms of formation of the pressure-sensitive adhesive layer, bonding workability of the transparent substrate, and cost.

  A transparent substrate bonded through such a pressure-sensitive adhesive layer imparts good mechanical strength to the film substrate and contributes particularly to the prevention of curling and the like. However, when it is required to be flexible, a plastic film of about 6 to 300 μm is usually used. When flexibility is not particularly required, a glass plate or film of about 0.05 to 10 mm is usually used. A plate-like plastic is used. Examples of the plastic material include the same materials as those described above.

  If necessary, an antiglare treatment layer or an antireflection layer for the purpose of improving visibility may be provided on the outer surface of the transparent substrate (the surface opposite to the pressure-sensitive adhesive layer), or the outer surface may be protected. A target hard coat layer may be provided. As the latter hard coat layer, for example, a cured film made of a curable resin such as a melanin resin, a urethane resin, an alkyd resin, an acrylic resin, or a silicon resin is preferably used.

  As described above, the transparent conductive laminate of the present invention has a specific crystal grain size and particle size distribution via the transparent first and second dielectric thin films on one side of the transparent film substrate. A transparent conductive thin film is laminated, and the transparent base is bonded to the other surface of the film base material via a transparent adhesive layer.

  The transparent conductive laminate has a physical property on the conductive thin film side of which the hardness on the conductive thin film side is preferably 1 GPa or more, particularly 1.5 GPa, and the elastic modulus on the conductive thin film side is 5 GPa or more, particularly 6 GPa. The above is preferable. By having such physical properties, even if the transparent conductive laminate is bent, the conductive thin film is not cracked or the electric resistance value is not deteriorated, and the bending resistance is high. As a transparent conductive laminated body, it can be conveniently used for the board | substrate of optoelectronics fields, such as a touchscreen. The upper limit of the hardness on the conductive thin film side is preferably 5 GPa or less, more preferably 4 GPa or less from the viewpoint of crack resistance, and the elastic modulus on the conductive thin film side is also from the point of crack resistance. 20 GPa or less, more preferably 16 GPa or less.

  The hardness and elastic modulus on the conductive thin film side can be measured by an indentation test (indenter indentation test) using, for example, a scanning probe microscope (JEOL. LTD / JEOL: JSPM-4200). . In the thin film hardness measurement, it is generally necessary that the indentation depth of the indenter be within about one-tenth of the film thickness.

  In the indentation test, an indenter is pressed against the DUT (that is, the conductive thin film side of the transparent conductive laminate) by applying a load to obtain an indentation curve (load-indentation depth curve). Based on the ratio of the maximum load Pmax and the projected contact area A between the indenter and the test object, the hardness H of the test object can be obtained from the following equation (1). Further, from the initial gradient S of the unloading curve of the indentation curve, the composite elastic modulus Er of the test object is obtained from the following equation (2). Further, the Young's modulus Es of the specimen is obtained from the following formula (3) from the Young's modulus Ei of the indenter, the Poisson's ratio vi of the indenter, and the Poisson's ratio vs of the specimen.

Here, in the following formula (2), β is a constant. The indenter is diamond, and its Young's modulus Ei is 1,140 GPa and Poisson's ratio is 0.07.
H = Pmax / A (1)
S = (2 / √π) · Er · β · √A (2)
Er = 1 / {(1-vs2) / Es + (1-vi2) / Ei} (3)
Here, since the Poisson's ratio vs of the conductive thin film as the test object is unknown, the above composite elastic modulus Er is defined as the elastic modulus referred to in the present invention. For details of the measurement, see, for example, W.H. C. Oliver and G.M. M.M. Phar, J .; Meter. Res. , Vol. 7, no. 6, June 1992, Handbook of Micro / Nanotriology, etc., and can be measured by a known method.

  FIG. 1 shows an example of a transparent conductive laminate according to the present invention, in which a transparent first dielectric thin film 2 and a transparent second dielectric thin film are formed on one surface of a transparent film substrate 1. 3. A transparent conductive thin film 4 is laminated in this order, and a transparent substrate 6 is bonded to the other surface via a transparent adhesive layer 5.

  FIG. 2 shows another example of the transparent conductive laminate of the present invention, in which a hard coat layer 7 is provided on the outer surface of the transparent substrate 6, and the other components are as follows. This is exactly the same as in FIG. 1, and the same numbers are assigned and description thereof is omitted.

  FIG. 3 shows an example of a touch panel using the transparent conductive laminate of the present invention. That is, a touch panel in which a pair of panel plates P1 and P2 having conductive thin films 4a and 4b are arranged to face each other via the spacer 8 so that the conductive thin films 4a and 4b provided to be orthogonal to each other face each other. 1 uses the transparent conductive laminate shown in FIG. 2 as one panel plate P1.

  In this touch panel, when the pressing point is touched with the input pen from the panel board P1, the conductive thin films 4a and 4b come into contact with each other and the electric circuit is turned on. Back, function as a transparent switch horizontal body. In that case, since the panel board P1 consists of said transparent conductive laminated body, it is excellent in the abrasion resistance of a conductive thin film, bending resistance, etc., and can maintain the said function stably over a long period of time.

  In addition, in said FIG. 3, the panel board P1 may be a transparent conductive laminated body shown in FIG. The panel plate P2 is formed by providing a conductive thin film 4b on a transparent substrate 9 made of a plastic film, a glass plate or the like. The transparent conductive laminate shown in FIG. 1 or FIG. 2 is the same as the panel plate P1. The body may be used.

  Hereinafter, examples of the present invention will be described in comparison with comparative examples, and will be described more specifically. In the following, “parts” means parts by weight.

  The crystal grain size and particle size distribution of the conductive thin film were evaluated by observing the surface of the conductive thin film with a field emission transmission electron microscope (FE-TEM, Hitachi, HF-2000). Specifically, the maximum grain size of the crystal was measured by the following method. First, an ITO film is formed on a polyester film by sputtering. This is left still in a petri dish, hexafluoroisopropanol is poured gently, and the polyester film is dissolved and removed. Then, the ITO thin film is scooped with a platinum mesh and fixed to the sample stage of a transmission electron microscope. This was photographed at a magnification of about 50,000 to 200,000 times according to each example, and the maximum grain size of crystals existing per 1.5 μm × 1.5 μm area was observed and evaluated.

Example 1
On one side of a transparent film substrate (light refractive index n ₁ = 1.66) made of a polyethylene terephthalate film (hereinafter referred to as PET film) having a thickness of 25 μm, a melamine resin: alkyd resin: organosilane condensate = 2: 2: 1 (weight ratio) of a cured film (light refractive index n ₂ = 1.54) formed of a thermosetting resin having a thickness of 150 nm, and a transparent first dielectric thin waist did.

Next, a second dielectric thin film made of a SiO ₂ thin film was formed on the first dielectric thin film by a silica coating method. That is, silica sol (“Colcoat P” manufactured by Colcoat Co.) diluted with ethanol so that the solid content concentration is 2% is applied on the first dielectric thin film, and dried at 150 ° C. for 2 minutes. And cured to form a SiO ₂ thin film (light refractive index n ₃ = 1.46) having a thickness of 30 nm, thereby forming a transparent second dielectric thin film.

After laminating the base thin film on the film base in this way, an atmosphere of 4 × 10 ⁻³ Pa consisting of 80% argon gas and 20% oxygen gas is further formed thereon (on the second dielectric thin film). Then, a composite oxide of indium oxide and tin oxide (light) having a thickness of 20 nm is formed by sputtering using a sintered body of a mixture of indium oxide and tin oxide (97% by weight of indium oxide, 3% by weight of tin oxide). A transparent conductive thin film (ITO thin film) having a refractive index of n ₄ = 2.00) was formed and heated at 150 ° C. for 1.5 hours. Table 2 shows the crystal grain size distribution of the conductive thin film.

Next, on the other surface of the PET film, a transparent acrylic pressure-sensitive adhesive layer (butyl acrylate: acrylic acid: vinyl acetate having a weight ratio of 100: 2: 5) having an elastic modulus adjusted to 10 N / cm ² is used. An acrylic pressure-sensitive adhesive comprising 1 part of an isocyanate-based crosslinking agent in 100 parts of a copolymer of a monomer mixture is formed to a thickness of about 20 μm, and further, a PET film having a thickness of 125 μm is formed thereon. A transparent substrate consisting of

  Next, 100 parts of acrylic / urethane resin (trade name “Unidic 17-806” manufactured by Dainippon Ink & Chemicals, Inc.) on the transparent substrate, hydroxycyclohexyl phenyl ketone (Ciba Specialty Chemicals) as a photopolymerization initiator. 5 parts of the product name “Irgacure 184” manufactured by the company was added, and a toluene solution diluted to a concentration of 50% by weight was applied. After drying at 100 ° C. for 3 minutes, an ozone-type high-pressure mercury lamp (80 W / cm, 15 cm collection) (Light type) By irradiating ultraviolet rays with two lamps and forming a hard coat layer having a thickness of 5 μm, a transparent conductive laminate having the structure shown in FIG. 2 was produced.

  This transparent conductive laminate is used as one panel plate, and as the other panel plate, an ITO thin film having a thickness of 30 nm is formed on a glass slope by the same method as described above. So that the gap between the two panel plates is 150 μm through a spacer having a thickness of 20 μm, and a touch panel as a switch structure was manufactured. In addition, each ITO thin film of both panel boards was previously formed so that it might mutually orthogonally cross prior to said opposing arrangement | positioning.

Example 2
A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that the thickness of the first dielectric thin film (cured coating) was changed to 200 nm. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Example 3
A transparent conductive laminate and a touch panel using the transparent conductive laminate were produced in the same manner as in Example 1 except that the thickness of the second dielectric thin film (SiO ₂ thin film) was changed to 60 nm. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Example 4
In the formation of the second dielectric thin film (SiO ₂ thin film), instead of the silica coating method, SiO ₂ is vacuum deposited by an electron beam heating method at a vacuum degree of 1 × 10 ^{−2 to} 3 × 10 ⁻² Pa. A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that a 30 nm thick SiO ₂ thin film was formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Example 5
In the formation of a conductive thin film (ITO thin film), a sintered body of a mixture of indium oxide and tin oxide (90% by weight of indium oxide, 10% by weight of tin oxide) is used as an evaporation material, and ITO having a thickness of 20 nm. A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that a thin film was formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Example 6
In the formation of the second dielectric thin film (SiO ₂ thin film), instead of the silica coating method, SiO ₂ is vacuum deposited by an electron beam heating method at a vacuum degree of 1 × 10 ^{−2 to} 3 × 10 ⁻² Pa. In forming a SiO ₂ thin film having a thickness of 30 nm and forming a conductive thin film (ITO thin film), a sintered body of a mixture of indium oxide and tin oxide (90% by weight of indium oxide, 10% by weight of tin oxide) as a deposition material %), A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that an ITO thin film having a thickness of 20 nm was formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Example 7
In the formation of the second dielectric thin film (SiO ₂ thin film), instead of the silica coating method, SiO ₂ is vacuum deposited by an electron beam heating method at a vacuum degree of 1 × 10 ^{−2 to} 3 × 10 ⁻² Pa. In the formation of a 30 nm thick SiO ₂ thin film and the formation of a conductive thin film (ITO thin film), a sintered body of a mixture of indium oxide and tin oxide (95% by weight of indium oxide, 5% by weight of tin oxide) is used as a deposition material. %), A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that an ITO thin film having a thickness of 20 nm was formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Comparative Example 1
A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that the first dielectric thin film (cured coating) was not formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Comparative Example 2
A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that the second dielectric thin film (SiO ₂ thin film) was not formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Comparative Example 3
In the formation of a conductive thin film (ITO thin film), a sintered body of a mixture of indium oxide and tin oxide (99% by weight of indium oxide, 1% by weight of tin oxide) is used as an evaporation material, and ITO having a thickness of 20 nm A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that a thin film was formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

Comparative Example 4
A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 5 except that the second dielectric thin film (SiO ₂ thin film) was not formed. Table 2 shows the crystal grain size distribution of the conductive thin film.

Comparative Example 5
In the formation of the second dielectric thin film (SiO ₂ thin film), instead of the silica coating method, SiO ₂ is vacuum deposited by an electron beam heating method at a vacuum degree of 1 × 10 ^{−2 to} 3 × 10 ⁻² Pa. In forming a SiO ₂ thin film having a thickness of 30 nm and forming a conductive thin film (ITO thin film), a sintered body of a mixture of indium oxide and tin oxide (99% by weight of indium oxide, 1% by weight of tin oxide) is used as an evaporation material. %), A transparent conductive laminate and a touch panel using the same were produced in the same manner as in Example 1 except that an ITO thin film having a thickness of 20 nm was formed. The grain size distribution of the conductive thin film crystals is shown in Table 2.

  Table 1 shows the material, refractive index, thickness and the like of each layer (thin film) for each of the transparent conductive laminates of Examples 1 to 7 and Comparative Examples 1 to 5. Table 2 shows the grain size distribution of the crystals of the conductive thin film.

  Moreover, about each transparent conductive laminated body, the hardness and elastic modulus by the side of an electroconductive thin film were measured with the following method with film resistance and light transmittance. These results were as shown in Table 3.

  In the measurement of the hardness and elastic modulus, a laminate in which the adhesive layer and the transparent substrate are not provided on the back surface of the film substrate (PET film), that is, one of the film substrates 1 as shown in FIG. A laminate in which a conductive thin film (ITO thin film) 4 was formed on the surface via a base thin film (first dielectric thin film 2 and / or second dielectric thin film 3) was used as a test object.

<Film resistance>
Using a four-terminal method, the surface electrical resistance (Ω / □) of the film was measured.

<Light transmittance>
The visible light transmittance at a light wavelength of 550 nm was measured using a spectroscopic analyzer UV-240 manufactured by Shimadzu Corporation.

<Hardness and elastic modulus on the conductive thin film side>
By an indentation test, the hardness and elastic modulus on the conductive thin film side were measured by the method described in detail herein. That is, as shown in FIG. 4, the device under test was fixed to the sample stage 20 with its conductive thin film (ITO thin film) 4 facing up. In this fixed state, the indenter 21 was pushed into the conductive thin film 4 side with a load in the vertical direction to obtain an indentation curve (load-push-in depth curve). From this, the hardness and elastic modulus on the conductive thin film side were calculated based on the formulas (1) and (2).

  The measurement used the scanning probe microscope (JEOL.LTD/JEOL:JSPM-4200). The indenter 21 was a diamond indenter (triangular pyramid) (TI-037 90 °). Using this indenter, indentation (indenter indentation) was performed once for 3 seconds with a load of 20 μN in the vertical direction, and the average value was obtained by measuring 5 times per sample. In each measurement, a sufficient distance between the measurement points was taken so that the influence of indentation would not occur.

  Next, about each touch panel of said Examples 1-7 and Comparative Examples 1-5, the hitting point characteristic, pen input durability, and bending pen input durability were measured with the following method. These results were as shown in Table 3.

<Spot characteristics>
Film resistance (Rd) after hitting the center hitting point 1 million times with a load of 100g from the panel plate side made of transparent conductive laminate using a 40 degree hardness urethane rubber rod (key tip 7R) Was measured, the rate of change (Rd / Ro) with respect to the initial film resistance (Ro) was determined, and the hit point characteristics were evaluated. In addition, the measurement of the said film resistance is performed about the contact resistance at the time of hitting of the electroconductive thin films arrange | positioned facing each other, and is represented by the average value.

<High-load pen input durability>
(A): From the panel plate side constituted by the transparent conductive laminate, sliding was performed 300,000 times with a load of 500 g using a pen made of polyacetal (pen tip R 0.8 mm). After sliding, the linearity was measured as follows, and the high load pen input durability was evaluated.

[Measurement method of linearity]
A voltage of 5 V was applied to the transparent conductive laminate, and the output voltage between terminal A (measurement start position) and terminal B (measurement end position) to which voltage was applied in the transparent conductive laminate was measured.
The linearity is calculated as follows when the output voltage at the measurement start position A is E _A , the output voltage at the measurement end position B is E _B , the output voltage at each measurement point X is E _X , and the theoretical value is E _XX. Can be obtained from
E _XX (theoretical value) = {X · (E _B −E _A ) / (B−A)} + E _A
Linearity (%) = _{[(E XX -E X) / (} E B -E A) ] × 100

  The outline of the linearity measurement is as shown in FIG. In an image display device using a touch panel, the position of the pen displayed on the screen is determined from the resistance value of the contact portion between the upper panel and the lower panel by being pressed with the pen. The resistance value is determined on the assumption that the output voltage distribution on the upper and lower panel surfaces is a theoretical line (ideal line). Then, if the voltage value deviates from the theoretical line as shown in the actual measurement value of FIG. 5, the pen position on the screen determined by the actual pen position and the resistance value is not well synchronized. The deviation from the theoretical line is linearity, and the larger the value, the greater the deviation between the actual pen position and the pen position on the screen.

  (B): Sliding was performed 100,000 times with each load using a pen (pen tip R0.8 mm) made of polyacetal from the panel plate side constituted by the transparent conductive laminate. The maximum load where the linearity after sliding was 1.5% or less was determined. The heavier the load, the better the pen input durability characteristics.

<Bend pen input durability>
(A): Sliding was performed 50,000 times at a load of 250 g using a pen (pen tip R0.8 mm) made of polyacetal from the panel plate side constituted by the transparent conductive laminate. At that time, as shown in FIG. 6, the gap between P1 and P2 of both panels is set to 300 μm, and the pen sliding angle θ is 4.0 ° when the input pen 10 is slid from the panel plate P1 side. did. After this sliding, the linearity of the transparent conductive laminate was measured in the same manner as described above, and the bending pen input durability was evaluated.

  (B): Sliding was performed 100,000 times with a load of 250 g using a pen (pen tip R0.8 mm) made of polyacetal from the panel plate side constituted by the transparent conductive laminate. At that time, as shown in FIG. 6, the angle θ is changed by adjusting the distance between P1 and P2 of both panels, and after sliding the input pen 10 is slid from the panel plate P1 side at each angle. The angle θ at which the linearity is 1.5% or less was determined. The larger this angle, the better the bending pen input durability characteristics.

  As is clear from the results of Table 3 above, the transparent conductive laminates of Examples 1 to 7 of the present invention have good transparency and satisfactory conductivity, and the hardness on the conductive thin film side is as follows. 1.5 GPa or more, elastic modulus on the conductive thin film side is 6 GPa or more, and has excellent characteristics. A touch panel using this has excellent hit point characteristics and pen input durability, and also has excellent bending pen input durability. It turns out that it is excellent.

  On the other hand, in Comparative Examples 1, 2, and 4 in which the first dielectric thin film or the second dielectric thin film was not formed, the transparency of the transparent conductive laminate was inferior, and the durability as a touch panel was improved. Inferior. Further, in Comparative Examples 3 and 5 in which the content of crystals having a particle size exceeding 300 nm exceeds 50 area% in the crystals of the conductive thin film, the bending pen input durability is poor.

It is sectional drawing which shows an example of the transparent conductive laminated body of this invention. It is sectional drawing which shows the other example of the transparent conductive laminated body of this invention. It is sectional drawing which shows the touch panel using the transparent conductive laminated body of this invention. It is explanatory drawing which shows the outline of the measurement of the hardness and elastic modulus by the side of a transparent conductive thin film. It is explanatory drawing which shows the outline of a linearity measurement. It is explanatory drawing which shows the outline of a measurement of bending pen input durability.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent film base material 2 Transparent 1st dielectric thin film 3 Transparent 2nd dielectric thin film 4 (4a) Transparent conductive thin film 5 Transparent adhesive layer 6 Transparent base | substrate 7 Hard-coat layer P1 Panel board P2 Panel plate 8 Spacer 4b Conductive thin film 9 Transparent substrate 10 Input pen 20 Sample stand 21 Indenter

Claims (9)

A transparent first dielectric thin film, a transparent second dielectric thin film, and a transparent conductive thin film are laminated in this order on one surface of a transparent film substrate having a thickness of 2 to 120 μm. A transparent substrate is bonded to the other surface of the material via a transparent adhesive layer,
The second dielectric thin film is an inorganic substance or a mixture of an organic substance and an inorganic substance,
The said conductive thin film is a transparent conductive laminated body characterized by the crystal | crystallization content whose maximum particle size is 300 nm or less exceeding 50 area% in the crystal | crystallization of the material which forms this thin film.   2. The transparent conductive laminate according to claim 1, wherein the transparent conductive thin film has a crystal content of a maximum particle size of 200 nm or less in a crystal of a material forming the thin film exceeding 50 area%.   The transparent conductive laminate according to claim 1 or 2, wherein the transparent conductive thin film has a hardness of 1.5 GPa or more and an elastic modulus of 6 GPa or more.   The conductive thin film is formed of indium oxide containing tin oxide, and the content of tin oxide with respect to the total of indium oxide and tin oxide is 2 to 50 weights. The transparent conductive laminate according to any one of the above.   The transparent conductive laminate according to claim 4, wherein the content of tin oxide is 3 to 15% by weight based on the total of indium oxide and tin oxide. The refractive index of light of the film substrate is n ₁ , the refractive index of light of the first dielectric thin film is n ₂ , the refractive index of light of the second dielectric thin film is n ₃ , and the refractive index of light of the conductive thin film. Is n ₄ ,
Their refractive indices satisfy the relationship n ₃ <n ₂ ≦ n ₁ <n ₄ ,
The thickness of the first dielectric thin film is 100 to 250 nm,
The transparent conductive laminate according to claim 1, wherein the second dielectric thin film has a thickness of 15 to 100 nm.   The transparent conductive laminate according to claim 1, wherein the first dielectric thin film is an organic material or a mixture of an organic material and an inorganic material.   The transparent conductive laminate according to claim 1, wherein the second dielectric thin film is an inorganic material formed by a vacuum deposition method.   The touch panel which arrange | positions a pair of panel board which has an electroconductive thin film through a spacer so that electroconductive thin films may oppose, At least one of a panel board is in any one of Claims 1-8. A touch panel comprising a transparent conductive laminate.

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