JP2005235678A - Transparent conductive laminate and touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive laminate which fully satisfies pen input durability when used as an input pen for a touch panel as a result of further improvement on durability. <P>SOLUTION: In the transparent conductive laminate, substrate of a thickness of 2 to 120 μm, a first transparent dielectric thin film, a transparent metal thin film or a metal oxide thin film, a second transparent dielectric thin film, and a transparent conductive thin film are laminated on a face of one side of a transparent film in this order, and transparent substrates are pasted together on the face of the other side of the film substrate, by interposing transparent bonding agent layers. Refractive indices satisfies a relationship of n<SB>3</SB><n<SB>2</SB>≤n<SB>1</SB><n<SB>4</SB>, when the refractive index of the film substrate is expressed as n<SB>1</SB>, that of the first dielectric body thin film is expressed as n<SB>2</SB>, that of the second dielectric body thin film is expressed as n<SB>3</SB>, and that of the conductive thin film is expressed as n<SB>4</SB>. The transparent metal thin film or the metal oxide thin film is of a thickness of 1 to 5 nm. <P>COPYRIGHT: (C)2005,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, Some applications cannot be used.

For this reason, in recent years, transparent conductive thin films based on various plastic films including 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 opposed to each other through a spacer are in strong contact with each other at a press hitting point with a pen from one panel plate side. It is desired to have good durability, that is, pen input durability. However, the conventional transparent conductive thin film as described above is inferior in pen input durability, and there is a problem that the life as a touch panel is shortened.

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).
Japanese Patent Laid-Open No. 2002-316378 (pages 2 to 4) Japanese Patent Laid-Open No. 2002-326301 (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 material and the conductive thin film has an appropriate relationship to improve transparency, and the scratch resistance of the conductive thin film, It improves the bending resistance and pen input durability for touch panels.

However, subsequent studies by the present applicant have found that the above transparent conductive laminate may still be insufficient in terms of pen input durability.

In light of the above circumstances, the present invention further improves the previously proposed transparent conductive laminate, and further improves the durability, and further improves the pen input durability for touch panels and the transparent conductive laminate. An object is to provide a touch panel used.

As a result of intensive studies to achieve the above object, the present inventors have found that in the previously proposed transparent conductive laminate, the first dielectric thin film provided as the base of the conductive thin film on the film substrate and the second dielectric thin film When a transparent metal thin film or metal oxide thin film is further provided between the dielectric thin film, the thickness of the thin film and the light refractive index of each thin film are selected so as to have an appropriate relationship. As well as satisfying various characteristics such as transparency, the durability of the conductive thin film provided on these thin films has been further improved, and the pen input durability for touch panels can be highly satisfied. As a result, the present invention has been completed.

That is, the present invention provides a transparent first dielectric thin film, a transparent metal thin film or metal oxide thin film, a transparent second dielectric on one surface of a transparent film substrate having a thickness of 2 to 120 μm. A thin film and a transparent conductive thin film are laminated in this order, and a transparent substrate is bonded to the other surface of the film base material via a transparent adhesive layer. Is.

In particular, the present invention has a refractive index of light of the film substrate n ₁ , a refractive index of light of the first dielectric thin film n ₂ , a refractive index of light of the second dielectric thin film n ₃ , and conductivity. When the refractive index of the light of the thin film is n ₄ , the transparent conductive laminate, the transparent metal thin film, or the metal oxide having the above structure satisfying the relationship of n ₃ <n ₂ ≦ n ₁ <n ₄ The transparent conductive laminate having the above-described configuration having a thin film thickness of 1 to 5 nm, and the transparent conductive laminate having the above-described configuration in which the first and second dielectric thin films are an organic substance, an inorganic substance, or a mixture of an organic substance and an inorganic substance. Can be provided.

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 spacers so that the conductive thin films are opposed to each other, and at least one of the panel plates has the above-described configuration. A touch panel comprising a transparent conductive laminate can be provided.

Thus, in the present invention, by providing a transparent metal thin film or metal oxide thin film between the film substrate and the conductive thin film, the thickness of the thin film and the refractive index of each thin film have an appropriate relationship. The transparent conductive laminate satisfying various characteristics such as transparency, and further improving the durability of the conductive thin film, and highly satisfying the pen input durability for touch panels. A touch panel using this can be provided.

The material for the film substrate in the present invention is not particularly limited, and an appropriate material can be used. Specifically, polyester resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyolefin Resin, polyvinyl alcohol resin, polyarylate resin, polyphenylene sulfide resin, polyvinylidene chloride resin, (meth) acrylic resin, and the like. 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, 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 pen input durability for the touch panel cannot be improved.

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

In the present invention, before providing a transparent conductive thin film on one surface of such a film substrate, a transparent first dielectric thin film, a transparent metal thin film or a metal oxide thin film, A transparent second dielectric thin film is laminated in this order. By laminating the base thin film in this way, the transparency and the scratch resistance and the bending resistance of the conductive thin film are improved, and good results are obtained in improving pen input durability for touch panels.

Each of the first dielectric thin film and the second dielectric thin film is preferably an organic substance, an inorganic substance, or a mixture of an organic substance and an inorganic substance.

Such dielectric thin film materials 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 ₃ (1.63), A1 ₂ O ₃ (1.63), etc. Inorganic materials (numbers in parentheses indicate the refractive index of light), organic materials such as acrylic resin, urethane resin, and siloxane polymer having a refractive index of light of about 1.4 to 1.6, and the inorganic material and the above A mixture of organic substances can be mentioned.

The first dielectric thin film and the second dielectric thin film can be formed using the above materials by a vacuum deposition method, a spuck ring method, an ion plating method, a coating method, or the like.

The first dielectric thin film has a thickness of usually 10 nm or more, preferably 10 to 3,000 nm. If the thickness is less than 10 nm, it is difficult to form a continuous film, and if it is too thick, there is a problem in bending resistance. The thickness of the second dielectric thin film is usually 10 nm or more, preferably 10 to 300 nm, more preferably 20 to 120 nm. If the thickness is less than 10 nm, it is difficult to form a continuous film, and improvement in transparency and scratch resistance cannot be expected so much. If it is too thick, improvement in transparency cannot be expected, and cracks are likely to occur.

The metal thin film or the metal oxide thin film is provided between the first dielectric thin film and the second dielectric thin film, and contributes to improving the adhesion between the two thin films. This greatly contributes to the improvement of pen input durability of the conductive thin film provided on the substrate.

Such metal thin film or metal oxide thin film materials include indium, tin, cadmium, zinc, titanium, antimony, aluminum, tungsten, molybdenum, chromium, tantalum, nickel, platinum, gold, silver, copper, palladium, etc. One kind or two or more kinds of metals or alloys selected from the above or oxides thereof may be mentioned.

The metal thin film or the metal oxide thin film can be formed using the above materials by a vacuum deposition method, a spuck ring method, an ion plating method, or the like.

The metal thin film or metal oxide thin film preferably has a thickness of 1 to 5 nm, particularly preferably 2 to 4 nm. This thin film may be a continuous thin film or a discontinuous thin film. When the thickness of the thin film is reduced, it becomes difficult to form the film uniformly, and there are cases where the film is not formed, that is, it is formed in the form of islands, but there is no particular problem. When the thickness of the thin film becomes too thick, the transparency is deteriorated, the flexibility is deteriorated, and cracks are generated to deteriorate the durability.

In the present invention, after laminating the base thin film on one surface of the film base in this way, a transparent conductive thin film is provided thereon.

The conductive thin film can be formed by the same method as that for the base thin film. The thin film material to be used is not particularly limited, and for example, indium oxide containing tin oxide, tin oxide containing antimony, and the like are preferably used.

The thickness of the conductive thin film is 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, and if it is too thick, the transparency tends to decrease.

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, it is desirable their refractive index satisfies a relationship _{n 3 <n 2 ≦ n 1} <n 4.

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 bonded to the other surface of the film base material provided with the transparent conductive thin film on one surface via the base thin film via the transparent adhesive layer.

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 continuously formed 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 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 substrate and the pen input durability 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 × 10 ⁵ to 1 × 10 ⁷ dyn / 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 × 10 ⁵ dyn / cm ² , the pressure-sensitive adhesive layer becomes inelastic, so that it is easily deformed by pressurization, causing unevenness in the film substrate and thus the conductive thin film, In addition, the adhesive tends to protrude from the cut surface, and the effect of improving the scratch resistance of the conductive thin film and the pen input durability as a touch panel is reduced. On the other hand, if it exceeds 1 × 10 ⁷ dyn / cm ² , the pressure-sensitive adhesive layer becomes hard and the cushion effect cannot be expected, and the scratch resistance of the conductive thin film and the pen input durability 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 improve the scratch resistance of the conductive thin film and the pen input durability 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 the formation of the pressure-sensitive adhesive layer, the bonding workability of the transparent substrate, and the cost.

A transparent substrate bonded through such an adhesive layer gives 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.

FIG. 1 shows an example of a transparent conductive laminate according to the present invention, in which a transparent first dielectric thin film 2, a transparent metal thin film or a metal oxide is formed on one surface of a transparent film substrate 1. A thin film 3, a second dielectric thin film 4, and a transparent conductive thin film 5 are laminated in this order, and a transparent substrate 7 is bonded to the other surface via a transparent adhesive layer 6.

FIG. 2 shows another example of the transparent conductive laminate of the present invention, in which a hard coat layer 8 is provided on the outer surface of the transparent substrate. The same reference numerals are assigned and the 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 5a and 5b are arranged to face each other via the spacer 9 so that the conductive thin films 5a and 5b provided so as 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 input pen 10 is pressed against the elastic force of the spacer 9 from the panel plate P1 side, the conductive thin films 5a and 5b come into contact with each other, and the electric circuit is turned on. When the pressure is released, the transparent switch structure returns to the original OFF state. At that time, since the panel plate P1 is composed of the above-described transparent conductive laminate, the conductive thin film has excellent scratch resistance and bending resistance, and has high pen input durability. The function can be maintained stably.

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 5b on a transparent substrate 11 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.

Weight ratio of melamine resin: alkyd resin: organosilane condensate on one surface of a transparent film substrate (light refractive index n ₁ = 1.66) made of polyethylene terephthalate film (PET film) having a thickness of 25 μm A cured film made of a 2: 2: 1 thermosetting resin (light refractive index n ₂ = 1.54) was formed to a thickness of 180 nm to form a transparent first dielectric thin film.

Next, a palladium thin film having a thickness of 3 nm was laminated on the first dielectric thin film by sputtering using palladium as a target to obtain a transparent metal thin film. Next, SiO ₂ (refractive index of light n ₃ = 1.46) is vacuum-deposited on the metal thin film by an electron beam heating method at a vacuum degree of (1-2) × 10 ⁻⁴ Torr. Was a transparent second dielectric thin film (SiO ₂ thin film) having a thickness of 40 nm.

After laminating the base thin film on the film substrate in this way, on this (on the second dielectric thin film), in an atmosphere of 4 × 10 ³ Torr further comprising 80% argon gas and 20% oxygen gas. A transparent conductive thin film (ITO thin film) made of a composite oxide of indium oxide and tin oxide (light refractive index n ₄ = 2.00) having a thickness of 20 nm by a reactive sputtering method using an indium-tins alloy Formed.

Next, on the other surface of the PET film, a transparent acrylic pressure-sensitive adhesive layer having an elastic modulus adjusted to 1 × 10 ⁶ dyn / cm ² (weight ratio of butyl acrylate: acrylic acid: vinyl acetate 100: 2 : Acrylic pressure-sensitive adhesive prepared by blending 1 part of an isocyanate-based crosslinking agent into 100 parts of a copolymer of 5 monomer mixture, and having a thickness of about 20 μm. A transparent conductive laminate having the structure shown in FIG. 1 was prepared by laminating a transparent substrate made of a 125 μm PET film.

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.

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 palladium thin film that was a metal thin film was not laminated.

When the scratch resistance of the ITO thin film was examined for each of the transparent conductive laminates of Example 1 and Comparative Example 1, the transparent conductive laminate of Example 1 was changed to the transparent conductive laminate of Comparative Example 1. In comparison, it was confirmed that the performance is equivalent or better.

Next, with respect to each touch panel of Example 1 and Comparative Example 1, the pen input durability test was performed by the following method, and the linearity (Rd) after the durability test was measured. The results were as shown in Table 1.

<Pen input durability test>
From the panel board side which consists of a transparent conductive laminated body of a touch panel, 300,000 times of sliding was performed by the load of 500 g using the pen (pen tip R0.8mm) which consists of polyacetal. After sliding, linearity was measured as follows, and pen input durability was evaluated.

<Measuring 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 can be obtained from the following calculation, assuming that the output voltage at the measurement start position A is EA, the output voltage at the measurement end position B is EB, the output voltage at each measurement point X is EX, and the theoretical value is EXX.
EXX (theoretical value) = (distance between A and X) × (EB−EA) / (distance between B and A)
+ EA

Linearity (%) = [(EXX−EX) / (EB−EA)] × 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, when the voltage value deviates from the theoretical line as shown in the actual measurement value of FIG. 4, 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.

In addition, the value of the following Table 1 shows the maximum value of the linearity in an Example and a comparative example.

Table 1
┌────┬─────────────────────┐
│ │ Pen input durability test │
│ │ [Linearity (Rd)] (%) │
├────┼─────────────────────┤
│Example 1│ 0.02 │
├────┼─────────────────────┤
│Comparative example 1│ 0.13 │
└────┴─────────────────────┘

As is clear from the results of Table 1 above, the touch panel of Example 1 of the present invention has a further improved linearity (Rd) after the durability test as compared with the touch panel of Comparative Example 1. It turns out that it has pen input durability.

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 a linearity measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent film base material 2 Transparent 1st dielectric thin film 3 Transparent metal thin film or metal oxide thin film 4 Transparent 1st dielectric thin film 5 (5a) Transparent conductive thin film 6 Transparent adhesive layer 7 Transparent base 8 Hard coat layer P1 Panel board P2 Panel board 9 Spacer 10 Input pen 5b Conductive thin film 11 Transparent base

Claims (5)

A transparent first dielectric thin film, a transparent metal thin film or metal oxide thin film, a transparent second dielectric thin film and a transparent conductive material are provided on one side of a transparent film substrate having a thickness of 2 to 120 μm. A transparent conductive laminate, wherein thin films are laminated in this order, and a transparent substrate is bonded to the other surface of the film substrate via a transparent adhesive layer.
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, the transparent conductive multilayer body according to claim 1 in which their refractive index satisfies a relationship _{n 3 <n 2 ≦ n 1} <n 4.
The transparent conductive laminate according to claim 1 or 2, wherein the transparent metal thin film or metal oxide thin film has a thickness of 1 to 5 nm.
The transparent conductive laminate according to claim 1, wherein the first and second dielectric thin films are an organic substance, an inorganic substance, or a mixture of an organic substance and an inorganic substance.
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 1-4. A touch panel comprising a transparent conductive laminate.

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