JPH06218864A - Transparent conductive laminate and touch panel - Google Patents

Abstract

PURPOSE:To provide a transparent conductive laminate having sufficient transparency, scratch resistance, and strength for use as a touch panel. CONSTITUTION:A transparent conductive laminate is constituted by forming a transparent dielectric membrane 2 on one surface of a transparent film base material with a thickness of 2-120mum and further forming a transparent conductive membrane 3 on the membrane and, when the light refractive index of the film base material is set to n1 and the light refractive index of the dielectric membrane 2 is set to n2 and that of the conductive membrane 3 is set to n3, the relation of n1<n3<n2 is satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive laminate having a film base material and a touch panel using the same.

[0002]

2. Description of the Related Art Generally, a thin film which is transparent in a visible light region and has conductivity is used for a new display system such as a liquid crystal display and an electroluminescence display, a transparent electrode in a touch panel, and an antistatic material for a transparent article. It is used to block electromagnetic waves.

Conventionally, as such a transparent conductive thin film,
A so-called conductive glass in which an indium oxide thin film is formed on glass is well known, but since the base material is glass, it is inferior in flexibility and workability and may not be preferable for some applications. .

Therefore, in recent years, in addition to flexibility and workability, it has excellent impact resistance and is lightweight,
Transparent conductive thin films based on various plastic films such as polyethylene terephthalate film have been used for awards.

[0005]

However, the conventional transparent conductive thin film using such a film substrate has a problem that it is inferior in transparency due to a large light ray reflectance on the surface of the thin film. There was a problem in that the thin film of the conductive film was inferior in scratch resistance, scratched during use, electrical resistance increased, and wire breakage occurred.

Particularly in a conductive thin film for a touch panel, a pair of thin films opposed to each other via a spacer are strongly in contact with each other at a pressing point from the panel plate side of one of them, and therefore, this is counteracted. It is desired that the conventional transparent conductive thin film has a good durability property, that is, a hitting property, which is inferior to such a property and the life of the touch panel is shortened accordingly.

In view of the above conventional problems, the present invention improves the transparency and scratch resistance of the conductive thin film in a transparent conductive thin film using a film substrate such as polyethylene terephthalate film. The purpose is to improve the dot characteristics for touch panels.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above object. As a result, a film base material having a specific thickness is used, and a transparent conductive film is formed on one surface of the base material. Thin film is formed through a transparent dielectric thin film having a larger refractive index of light than this thin film, while another transparent substrate is attached to the other surface through a transparent pressure-sensitive adhesive layer. The inventors have found that the scratch resistance of the conductive thin film can be improved and that the dot properties for touch panels can be improved, and the present invention has been completed.

That is, the first aspect of the present invention is that the thickness is 2 to
A transparent dielectric thin film is formed on one surface of a 120 μm transparent film substrate, and a transparent conductive thin film is formed on the transparent dielectric thin film.
A transparent electroconductive laminate comprising a transparent substrate adhered to the other surface via a transparent adhesive layer, wherein the film substrate has a light refractive index of n ₁ , and the dielectric thin film has a light refraction index. the rate n _2, and the refractive index of light of the conductive thin film was n _3, which relates to a transparent conductive laminate according to satisfy the relation of _{n 1 <n 3 <n 2} .

A second aspect of the present invention is a touch panel in which a pair of panel plates having a conductive thin film are opposed to each other via a spacer so that the conductive thin films face each other. The touch panel is characterized in that the panel plate is made of the transparent conductive laminate according to the first aspect of the present invention.

[0011]

As the film base material used in the present invention, various transparent plastic films can be used. Specific examples thereof include polyethylene terephthalate, polyimide, polyether sulfone, polyether ether ketone, polycarbonate, polypropylene, polyamide, polyacryl and cellulose propionate.

The thickness of these film base materials is 2 to 120.
It is necessary to be in the range of μm, particularly preferably 6 to 1
It is preferably in the range of 00 μm. If the thickness is less than 2 μm, the mechanical strength of the substrate is insufficient, and it becomes difficult to continuously form a dielectric thin film, a conductive thin film, and an adhesive layer by making this substrate into a roll shape. On the other hand, when it 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 properties for a touch panel.

The surface of this film substrate is previously subjected to etching treatment such as sputtering, corona discharge, flame, ultraviolet ray irradiation, electron beam irradiation, chemical conversion, oxidation or the like, or an undercoating treatment, and the above-mentioned dielectric thin film is provided thereon. You may make it improve the adhesiveness with respect to a base material. Further, before providing the dielectric thin film, if necessary, it may be removed by dusting or cleaning by solvent cleaning or ultrasonic cleaning.

In the present invention, a transparent dielectric thin film is formed on one surface of such a film substrate. It is necessary that the refractive index n ₂ of light of this thin film is larger than the refractive index n ₃ of light of the conductive thin film provided on this thin film.
Since the refractive index n ₃ of light of a conductive thin film is usually about 2, the refractive index n ₂ of light of a dielectric thin film is usually 2.0.
It is preferably about 5 to 2.4. By forming this dielectric thin film, mainly the transparency and the scratch resistance of the conductive thin film are greatly improved, and good results are also obtained in the improvement of the dot characteristics for the touch panel.

Examples of materials for such a dielectric thin film include CeO ₂ (2.3), Nd ₂ O ₃ (2.15),
Sb ₂ O ₃ (2.1), TiO ₂ (2.35), Ta ₂
O ₅ (2.1), ZrO ₂ (2.05), ZnO (2.
1), ZnS (2.3), etc. [the numerical value in () of each of the above materials is the refractive index n ₂ of light], and these inorganic materials and acrylic resins, urethane resins, siloxane polymers, etc. There are mixtures with organic substances. Among these, CeO ₂ , TiO ₂ , ZnS and the like having a light refractive index n ₂ of about 2.3 to 2.4 are particularly suitable for practical use.

The thickness of the dielectric thin film is preferably 50 Å or more, preferably 100 to 3,000 Å, particularly preferably 400 to 1,600 Å. When it is less than 50Å, 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 cracking may occur, which is not preferable.

As the method for forming the dielectric thin film, there are, for example, a vacuum vapor deposition method, a sputtering method, an ion plating method, a coating method and the like, and an appropriate method is adopted depending on the kind of the above material and the required film thickness. can do.

In the present invention, after the transparent dielectric thin film is formed as described above, the transparent conductive thin film is further formed on this thin film. As a method for forming the conductive thin film,
The same technique as in the case of the dielectric thin film can be adopted. The thin film material used is not particularly limited, and for example, indium oxide containing tin oxide and tin oxide containing antimony are preferably used.

The light refractive index n ₃ of the conductive thin film made of these materials is usually about 2 as described above, and the light refractive index n ₁ of the film base material is usually 1.4 to 1.7. Due to the degree, it becomes larger than this refractive index n ₁ . Therefore, the relationship between these and the light refractive index n ₂ of the dielectric thin film is n ₁ <
n ₃ <n ₂ .

The thickness of this conductive thin film is preferably 50 Å or more, and if it is thinner than this, the surface resistance is 10 ³ Ω /
□ It is difficult to form a continuous film with good conductivity below. Further, if it is made too thick, the transparency may be deteriorated. Therefore, a particularly preferable thickness is 100 to 3,0.
It is good to set it to about 00Å.

A transparent substrate is attached to the other surface of the film substrate on which such a transparent dielectric thin film and a transparent conductive thin film are sequentially formed, with a transparent adhesive layer interposed therebetween. For this bonding, the above-mentioned pressure-sensitive adhesive layer may be provided on the transparent substrate and the above-mentioned film base material may be bonded thereto, or conversely, the above-mentioned pressure-sensitive adhesive layer may be bonded to the film base material. May be provided and a transparent substrate may be attached thereto. The latter method is more advantageous in terms of productivity because the pressure-sensitive adhesive layer can be continuously formed by making the film substrate into a roll shape.

The pressure-sensitive adhesive layer can be used without particular limitation as long as it has transparency. For example, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive and the like can be used. This 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 dot properties for a touch panel by the cushioning effect after the transparent base material is adhered. From the viewpoint of better exhibiting this function, its elastic coefficient is set to 1 × 10 ⁵ to 1 × 10.
Range of ⁷ dyn / cm ² , thickness of 1 μm or more, usually 5-10
It is desirable to set in the range of 0 μm.

When the above elastic modulus is less than 1 × 10 ⁵ dyn / cm ² , the pressure-sensitive adhesive layer becomes inelastic, so that it is easily deformed by pressurization to cause unevenness on the film substrate and hence the conductive thin film. Moreover, the pressure-sensitive adhesive is likely to protrude from the processed cut surface, and the effect of improving the scratch resistance of the conductive thin film and the dot properties for a touch panel is reduced. On the other hand, when the elastic modulus exceeds 1 × 10 ⁷ dyn / cm ² , the pressure-sensitive adhesive layer becomes hard and the cushioning effect cannot be expected, so that the scratch resistance of the conductive thin film and the dot property for a touch panel cannot be improved. .

If the thickness of the pressure-sensitive adhesive layer is less than 1 μm, the cushioning effect cannot be expected, so that the abrasion resistance of the conductive thin film and the hitting property for a touch panel cannot be expected to be improved. If the thickness is too large, the transparency may be impaired, and it may be difficult to obtain good results in terms of workability of forming the pressure-sensitive adhesive layer and bonding of the transparent substrate and cost.

The transparent substrate adhered via such an adhesive layer imparts good mechanical strength to the film substrate and particularly contributes to the prevention of curling. If it is required to be flexible even after being attached, a plastic film of about 6 to 300 μm is usually used. If flexibility is not particularly required, a glass plate of about 0.05 to 10 mm is usually used. A film-shaped or plate-shaped plastic is used. As the material for the plastic, the same materials as those for the above-mentioned film base material can be mentioned.

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

FIG. 1 shows an example of the transparent electroconductive laminate of the present invention. A transparent dielectric thin film 2 is formed on one surface of a transparent film substrate 1 and a transparent electroconductive thin film is formed on the transparent dielectric thin film 2. 3 is formed, and the transparent substrate 5 is attached to the other surface of the transparent substrate 5 via the transparent adhesive layer 4. FIG. 2 shows another example of the transparent conductive laminate of the present invention, in which the hard coat treatment layer 6 is provided on the outer surface of the transparent substrate 5, and The configuration is exactly the same as in FIG.

FIG. 3 shows an example of a touch panel using the transparent conductive laminate of the present invention, in which a pair of panel plates P1 and P2 having conductive thin films P _1d and P _2d are arranged in stripes orthogonal to each other. In the touch panel in which the conductive thin films P _1d and P _2d formed in a strip shape are opposed to each other with the spacer S interposed therebetween, the transparent conductive film shown in FIG. A laminated body is used.

When the touch panel is pressed against the elastic force of the spacer S by the finger M of the hand from the panel plate P1 side, the conductive thin films P _1d and P _2d come into contact with each other to generate electricity. When the circuit is turned on and the above pressure is released, the original O
It functions as a transparent switch structure that returns to the FF state. At this time, since the panel plate P1 is made of the above-mentioned transparent conductive laminate, the conductive thin film has excellent scratch resistance and hitting property, and the above functions can be stably maintained over a long period of time.

In FIG. 3, the panel plate P1 may be the transparent conductive laminate shown in FIG. The panel plate P2 is a transparent substrate 5'made of a plastic film or a glass plate and a conductive thin film _P2d provided on the transparent substrate 5 '. The transparent conductive film shown in FIG. A layered product may be used.

[0031]

As described above, according to the present invention, the scratch resistance of the conductive thin film and the hitting property as a touch panel are improved based on the hard effect of the dielectric thin film and the cushioning effect of the adhesive layer. It is possible to provide a transparent conductive laminate having significantly improved transparency due to the antireflection effect based on the combination of the dielectric thin film and the conductive thin film, and to provide a touch panel using the same.

[0032]

EXAMPLES Examples of the present invention will be described below for more specific description. In the following, "parts" means "parts by weight".

Example 1 TiO ₂ was formed on one surface of a 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.
(1-2) × 10 ⁻⁴ Tor by electron beam heating method
Vacuum-deposited at a vacuum degree of r to obtain Ti with a thickness of about 1,000Å
A transparent dielectric thin film (hereinafter referred to as TiO ₂ thin film) made of O ₂ (light refractive index n ₂ = 2.35) was formed.

Next, 4 × 10 ⁻³ T consisting of 80% argon gas and 20% oxygen gas was formed on the TiO ₂ thin film.
In an atmosphere of orr, a compound oxide of indium oxide and tin oxide having a thickness of 300 Å (refractive index n _{3 of} light = _{3) was} formed by a reactive sputtering method using an indium-tin alloy.
A transparent conductive thin film (hereinafter referred to as an ITO thin film) made of 2.00) was formed.

Then, on the other surface of the PET film, an acrylic transparent pressure-sensitive adhesive layer (weight of butyl acrylate, acrylic acid and vinyl acetate) whose elastic modulus was adjusted to 1 × 10 ⁶ dyn / cm ² was used. 100 parts acrylic copolymer having a ratio of 100: 2: 5 and 1 part isocyanate-based cross-linking agent) are formed to a thickness of about 20 μm, and a PET film having a thickness of 125 μm is formed thereon. A transparent substrate composed of the above was bonded to produce a transparent conductive laminated film having a structure shown in FIG.

This transparent conductive laminated film was used as one panel plate and the other panel plate with a thickness of 3 on a glass plate.
Using a 00 Å ITO thin film formed by the same method as above, both panel plates are arranged facing each other with a spacer of 100 μm in thickness so that the ITO thin films face each other to form a switch structure. A touch panel was manufactured. The ITO thin films on both panel plates were formed in advance in stripes orthogonal to each other prior to the above facing arrangement.

Example 2 On one side of a PET film having a thickness of 125 μm, 100 parts of an acrylic / urethane type resin [UNIDIK 17-806 manufactured by Dainippon Ink and Chemicals, Inc.] was added to hydroxycyclohexyl as a photopolymerization initiator. Add 5 parts of phenylketone [Irgakiure 184 manufactured by Ciba-Geigy Co., Ltd.],
Apply a toluene solution diluted to a concentration of 50% by weight,
After drying at 100 ° C. for 3 minutes, ultraviolet rays were immediately irradiated with two ozone type high pressure mercury lamps (80 W / cm, 15 cm condensing type) to form a hard coat treatment layer having a thickness of 5 μm.

PET formed with this hard coat treated layer
The film is used as a transparent substrate, and the transparent substrate is
In the same manner as in Example 1 except that the surface opposite to the doctrine-treated layer was adhered via an adhesive layer,
A transparent conductive laminated film having the structure shown in FIG. 2 was produced.
Further, using this laminated film, a touch panel having a structure shown in FIG. 3 was produced in the same manner as in Example 1.

Examples 3, 4 The thickness of the TiO ₂ thin film was 400 Å (Example 3), 1, 60
Two types of transparent conductive laminated films having the structure shown in FIG. 2 were produced in the same manner as in Example 2 except that the thickness was changed to 0Å (Example 4). Also, using these laminated films, two types of touch panels having the structure shown in FIG. 3 were produced in the same manner as in Example 1.

Example 5 ZnS was replaced by an electron beam heating method in place of the TiO ₂ thin film,
(1 to 2) × 10 ⁻⁴ Torr vacuum-deposited at a vacuum degree,
ZnS having a thickness of about 1,000Å (refractive index of light n ₂ = 2.
A transparent conductive laminated film having the structure shown in FIG. 2 was produced in the same manner as in Example 2 except that the transparent dielectric thin film consisting of 3) was formed. Further, using this laminated film, a touch panel having a structure shown in FIG. 3 was produced in the same manner as in Example 1.

Comparative Example 1 A transparent conductive laminated film was prepared in the same manner as in Example 1 except that the formation of the TiO ₂ thin film and the pressure-sensitive adhesive layer and the bonding of the transparent substrate were not performed, and this film was used. Then, a touch panel was produced in the same manner as in Example 1.

Comparative Example 2 A transparent conductive laminated film was produced in the same manner as in Example 1 except that the TiO ₂ thin film was not formed, and this film was used in the same manner as in Example 1. A touch panel was produced.

Comparative Example 3 A transparent conductive laminated film was prepared in the same manner as in Example 1 except that the pressure-sensitive adhesive layer was not formed and the transparent substrate was not adhered. A touch panel was produced in the same manner as in 1.

Comparative Example 4 A transparent conductive laminated film was prepared in the same manner as in Example 1 except that a PET film having a thickness of 125 μm was used as a film base material, and this film was also used.
A touch panel was produced in the same manner as in Example 1.

For each of the transparent conductive laminated films of Examples 1 to 5 and Comparative Examples 1 to 4 described above, the film resistance, the light transmittance and the scratch resistance of the conductive thin film were measured by the following methods. In addition, Examples 1 to 5 and Comparative Examples 1 to 4 described above
With respect to each of the touch panels, the dot properties were measured by the following method. The results are shown in Table 1.

<Film Resistance> The surface electric resistance (Ω / □) of the film was measured by the two-terminal method.

<Light Transmittance> A visible light transmittance at a light wavelength of 550 nm was measured by using a spectrophotometer UV-240 manufactured by Shimadzu Corporation.

<Abrasion resistance of conductive thin film> Using Hayden surface property measuring instrument TYPE-HEIDON14 manufactured by Shinto Kagaku Co., Ltd., abrasion: gaze (Japanese Pharmacopoeia type I), load: 100 g / cm ² , Scratch rate: 30 cm / min, number of scratches: 100 times (50 reciprocations), the film resistance (Rs) was measured after rubbing the surface of the conductive thin film, and the rate of change with respect to the initial film resistance (Ro) (Rs / Ro)
Then, the scratch resistance was evaluated.

<Spotting Characteristics> From a panel plate side composed of a transparent conductive laminated film, a rod (key point 7R) made of urethane rubber having a hardness of 40 degrees is used and a load of 100 g is applied to 100.
After performing the center dot for 10,000 times, the film resistance (R
d) was measured, the rate of change (Rd / Ro) with respect to the initial film resistance (Ro) was determined, and the dot characteristics were evaluated. The film resistance is measured by measuring the contact resistance of the conductive thin films arranged opposite to each other at the time of hitting, and is represented by an average value thereof.

[0050]

[Table 1]

From the results shown in Table 1, the transparent conductive laminated film of the present invention has good conductivity and transparency, and the conductive thin film has excellent scratch resistance, and the transparent conductive laminated film is also excellent. It is obvious that the touch panel having excellent hitting properties can be manufactured by using.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a transparent conductive laminate of the present invention.

FIG. 2 is a cross-sectional view showing another example of the transparent conductive laminate of the present invention.

FIG. 3 is a sectional view showing an example of the touch panel of the present invention.

[Explanation of symbols]

1 Transparent Film Substrate 2 Transparent Dielectric Thin Film 3 Transparent Conductive Thin Film 4 Transparent Adhesive Layer 5 Transparent Substrates P1, P2 Pair of Panel Plates P _1d , P _2d Conductive Thin Film S Spacer

Claims (2)

[Claims] 1. A transparent film substrate having a thickness of 2 to 120 μm, wherein a transparent dielectric thin film is formed on one surface of the transparent film substrate, and a transparent conductive thin film is formed on the transparent dielectric thin film, and a transparent adhesive layer is formed on the other surface. A transparent conductive laminate obtained by bonding a transparent substrate via a transparent substrate, the refractive index of light of the film base material is n ₁ , the refractive index of light of the dielectric thin film is n ₂ , and the conductive thin film is When the refractive index of light of n is ₃ , the transparent electroconductive laminate is characterized by satisfying the relationship of n ₁ <n ₃ <n ₂ . 2. A pair of panel plates having a conductive thin film,
A touch panel in which conductive thin films are opposed to each other via a spacer so that at least one panel plate is made of the transparent conductive laminate according to claim 1.