JPH11110110A - Transparent conductive film for touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film improved in description resistance, alkali resistance and adhesion by making the linearity lower than a specified value and making the retardation value lower than a specified value after the polyacetal pen of a specified diameter is used and reciprocatively moved plural times with a specified load. SOLUTION: Concerning a touch panel sample, a transparent conductive film 3 is laminated through a spacer 2 onto glass 4 with conductive film 1 and further, a polarizing film 5 with hard coat is laminated through an adhesive layer 4 onto the film 3. When measuring the linearity of the transparent conductive film 3 to be used as the transparent electrode of a touch panel, the film is reciprocatively moved 100,000 times with the load of 250 g (at the speed of 3 reciprocation per second for the distance of 35 mm for one side) while using a polyacetal pen 6 having the diameter of 8 mm. After this transparent conductive film 3 is reciprocatively moved 100,000 times, its linearity is lower than 1.45% and its retardation value is lower than 15 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film which is excellent in writing resistance, alkali resistance and adhesion, has optical isotropy suitable for use in a transparent touch panel, and can be suitably used as a transparent electrode of a touch panel. About.

[0002]

2. Description of the Related Art In recent years, a transparent touch panel that allows input by simply touching a display screen with a finger or pressing with a pen has become widespread. This touch panel has an analog type and a matrix type. In the former analog type, two transparent conductive substrates provided with electrodes at both ends are opposed to each other via a spacer, and a voltage is applied to upper and lower electrodes, and the voltage value at the pressed position is set as the position of the XY coordinate. Detect. In the latter matrix type, two transparent conductive substrates each having a conductive layer formed in a strip shape are arranged in a matrix, and the pressed position is detected by each electrode.

[0003] Since a normal transparent conductive film for a touch panel is used by being superimposed on the uppermost layer of a liquid crystal display element,
Although attention is paid to transparency, optical isotropy is not considered. Therefore, it basically has a configuration in which a conductive layer (mainly an ITO film) is laminated on a glass or polymer film, has a visible light transmittance of at least 80% and a surface resistance of 1000Ω / □ or less. , And excellent writing resistance.

On the other hand, as a material for a next-generation touch panel, it is required to reduce the reflection of light and improve the visibility. However, the above-mentioned conventional laminated structure is required to satisfy these requirements sufficiently. Can not.

[0005] Therefore, to improve the visibility, the installation of a transparent conductive film under a polarizing plate of a liquid crystal display element has been studied, and is expected to be an effective method. In this method, the base film is required to have an optically isotropic function because a transparent conductive film is incorporated under the polarizing plate.

Meanwhile, a conventional conductive film layer is obtained by doping indium oxide or tin oxide with silicon oxide, aluminum oxide, or the like (Japanese Patent Laid-Open No. 4-206403), or obtained by doping indium oxide or tin oxide with nitrogen (particularly, Japanese Patent Laid-Open Publication No. Kaihei 4-3
08612). However, simply forming a transparent conductive film layer on a transparent polymer substrate cannot withstand a 250 g load 100,000 character writing test required for analog use.

Japanese Patent Application Laid-Open No. 6-64105 discloses a gas-barrier transparent conductive laminate in which an oxidized organic silicon polymer layer is laminated on at least one surface of a polymer film and a conductive layer is laminated on one surface. Is described. However, in these examples, a PET film is used, and the retardation value is too large for a next-generation touch panel application of a type installed under a polarizing plate, which is not suitable.

[0008] Films having a low retardation value include polycarbonate, polyether sulfone, polyarylate, polyacrylate, and the like. Resin layers are applied to both surfaces of the film from the viewpoints of chemical resistance, stiffness and workability. Things are being developed. However, when an organosilicon polymer or an ITO film is formed directly on these films, a PET film (50 gf / inch or more) is required.
The adhesiveness was weaker (approximately 30 gf / inch) as compared with that of the prior art, and it was not practically used until now.

[0009]

As described above, the conventional transparent conductive substrate basically has a layer structure of glass or polymer film / conductive layer (mainly ITO film).

[0010] When a glass substrate is used, a chemically stable transparent conductive film layer is formed by heating the substrate to a high temperature.
There is a problem that it is thick. On the other hand, when a polymer substrate (polymer film) is used, the problem unlike the glass substrate does not occur. However, when an optically isotropic transparent polymer substrate is used, the temperature at which the transparent conductive film layer is formed is limited to the heat-resistant temperature of the polymer substrate, and the temperature must be lowered. Therefore, it is not easy to form a transparent conductive film layer having excellent writing resistance and adhesion. Furthermore, when a conventionally proposed polymer substrate is used, optical isotropy,
It is difficult to satisfy all required properties such as transparency, heat resistance, chemical resistance, and adhesion.

That is, an object of the present invention is to provide a transparent conductive film for a touch panel which solves the above-mentioned problems which could not be solved conventionally, and which is particularly excellent in writing resistance, alkali resistance and adhesion. And

[0012]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention described below.

That is, the present invention uses a polyacetal pen having a diameter of 8 mm and performs 100,000 reciprocations (3
The linearity after a round trip / one second and a one-way distance of 35 mm) is 1.5% or less, and the retardation value is 15
a transparent conductive film for a touch panel having a thickness of not more than 10 nm, and a layer (B) made of silicon oxynitride on one main surface of the transparent polymer substrate (A) having the above-mentioned performance,
The transparent conductive film for a touch panel is formed by sequentially laminating a transparent conductive film layer (C) made of indium tin oxide.

Preferably, the transparent polymer substrate (A)
Is subjected to corona discharge treatment and / or glow discharge treatment, and a layer (B) made of silicon oxynitride is laminated on the treated surface, and desirably, one of the transparent polymer substrates (A) On the main surface, a metal thin film layer or a metal oxide thin film layer (D) mainly composed of nickel is laminated, and a layer (B) composed of silicon oxynitride is laminated on the layer (D). One main surface of the polymer substrate (A) is subjected to corona discharge treatment and / or glow discharge treatment, and a metal thin film layer or a metal oxide thin film layer (D) mainly composed of nickel is laminated on the treated surface. A transparent conductive film for a touch panel in which a layer (B) made of silicon oxynitride is laminated on (D), and the thickness of the layer (B) made of silicon oxynitride is preferably 3 to 30 nm.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The transparent conductive film for a touch panel according to the present invention is characterized by having the above-mentioned specific linearity and retardation value. Specifically, such a property is obtained by forming a layer (B) made of silicon oxynitride on one main surface of the transparent polymer substrate (A),
By successively laminating the transparent conductive film layers (C) made of indium tin oxide, a good result can be obtained.

The transparent polymer substrate (A) may be any transparent film having an optically isotropic function, and there is no particular limitation on the material and the like. For example, a polymer substrate composed of a homopolymer such as polycarbonate, polyethersulfone, polyarylate, polyacrylate, and polysulfone, and a copolymer of a monomer of these resins with a copolymerizable monomer, and the like can be given.

Known additives such as a curing agent, a lubricant, an antistatic agent, a hard coating agent, a moisture-proof coating agent, a gas barrier coating agent, a corrosive agent, etc. in or on the transparent polymer substrate (A). May be added or laminated. Further, the surface of the transparent polymer substrate (A) may be subjected to a known surface treatment, for example, a surface roughening treatment, an anchor coat, or the like. The thickness of the transparent polymer substrate (A) is not particularly limited.
It is preferably about 250 μm.

The layer (B) made of silicon oxynitride (SiOxNy) has 2x + y ≦ 4, x = 0.05 to 2, y = 0.
It is preferable to satisfy 5 to 4. It is preferable that the reaction gas at the time of film formation is kept at nitrogen / argon = 0.6 to 4. If the nitrogen / argon ratio is 0.6 or more, good results in terms of transparency and alkali resistance can be obtained.
If the amount of argon is set to 4 or less, good results can be obtained in terms of sputtering speed and the like. Further, a small amount of oxygen may be added to improve transparency by lowering the refractive index, and hydrogen may be added to prevent excessive oxidation.

The thickness of the layer (B) made of silicon oxynitride is preferably about 3 to 30 nm. By setting the thickness within this range, better results can be obtained in both surface resistance and visible light transmittance.

As a method for forming the layer (B) made of silicon oxynitride, any of the conventionally known techniques such as a vacuum deposition method, a sputtering method, and an ion plating method can be adopted. In the sputtering method, silicon or silicon nitride may be used for the target.

The transparent conductive film layer (C) may be made of indium tin oxide. Considering the specific resistance and the visible light transmittance, the tin content is preferably 3 to 50% by weight.
Since the thickness affects the surface resistance and the visible light transmittance, the thickness may be appropriately determined according to the required surface resistance and the visible light transmittance. Usually, about 10 to 50 nm is preferable.

The surface resistance of the transparent conductive film layer (C) is preferably about 200 to 1000 Ω / □.

As a method of forming the transparent conductive film layer (C),
Any of the conventionally known techniques such as a vacuum deposition method, a sputtering method, and an ion plating method can be adopted. In the sputtering method, indium tin oxide or an indium tin alloy may be used as a target.

In the present invention, one main surface of the transparent polymer substrate (A) is subjected to a corona discharge treatment and / or a glow discharge treatment, and a layer (B) made of silicon oxynitride is laminated on the treated surface. It is desirable to do. By these treatments, the surface of the transparent polymer substrate (A) is activated and cleaned, and the adhesion to the layer (B) made of silicon oxynitride is further improved.

There are no particular restrictions on the conditions of the corona discharge treatment, but usually, the treatment is carried out in the atmosphere at 10 to 100 kV.
The conditions for the glow discharge treatment are not particularly limited, but usually are 2
Under a reduced pressure of 0 Pa or less, a gas such as oxygen, nitrogen, nitrogen monoxide, argon, or hydrogen may be used.

In the present invention, a metal thin film layer or a metal oxide thin film layer (D) mainly composed of nickel is laminated on one main surface of the transparent polymer substrate (A). It is desirable to laminate a layer (B) made of silicon oxynitride on the substrate. By interposing such a layer (D) between the transparent polymer substrate (A) and the layer (B) made of silicon oxynitride, the alkali resistance becomes better, and a step of using an alkali for etching or the like. It is extremely effective when there is.

This layer (D) is mainly formed of nickel, and may be an alloy with a metal such as chromium or iron. Also, a metal thin film or a metal oxide thin film may be used.
Instead of a continuous film, an island-shaped discontinuous film may be used. The thickness may be appropriately determined as long as the thickness does not impair the alkali resistance, particularly considering the visible light transmittance. The calculated thickness is usually preferably about 0.2 to 3 nm.
When the thickness is 0.2 nm or more, the effect of alkali resistance is more favorably obtained, and when the thickness is 3 nm or less, transparency is further improved.

As the method for forming the layer (D), any of the conventionally known techniques such as a vacuum deposition method, a sputtering method, and an ion plating method can be adopted.

In the present invention, one main surface of the transparent polymer substrate (A) is further subjected to a corona discharge treatment and / or a glow discharge treatment, and a metal thin film layer or a metal oxide mainly composed of nickel is formed on the treated surface. It is desirable that a thin film layer (D) be laminated, and a layer (B) made of silicon oxynitride be laminated on this layer (D). As a result, the effect of improving the adhesion by the specific treatment described above and the effect of improving the alkali resistance by the layer (D) can be simultaneously exhibited, and a better product can be obtained.

The transparent conductive film of the present invention has a diameter of 8 m.
m with a 250 g load using a 10 m polyacetal pen.
The linearity after every reciprocation (3 reciprocations / 1 second, one-way distance 35 mm) is 1.5% or less. Hereinafter, this linearity measurement method (writing characteristic evaluation method)
This will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing a state of measuring the linearity of a touch panel sample of the present invention. In this figure, in the touch panel sample, a transparent conductive film 3 is laminated on a glass 1 with a conductive film via a spacer 2, and a polarizing film 5 with a hard coat is further laminated thereon via an adhesive layer 4. It becomes.
When measuring the linearity of the transparent conductive film 3 used as a transparent electrode of this touch panel, as shown in FIG. 1, a 100,000 reciprocation with a 250 g load (speed: 3) using a polyacetal pen 6 having a diameter of 8 mm. Round trip / 1
Second, one-way distance 35 mm).

FIG. 2 is a schematic plan view showing a state of measuring the linearity of the touch panel sample of the present invention. When sliding the polyacetal pen 6, as shown in FIG. 2, the sliding between the electrodes 9 (sliding portion 8) is reciprocated.

FIG. 3 is a graph for explaining a method of measuring linearity. When the relationship between the distance from one electrode 9 to the measurement point and the voltage is measured, it should ideally be a straight line (ideal voltage) as shown by the chain line in FIG. However, actually, the relationship between the distance and the voltage is a curve (measured voltage) as shown by the solid line in FIG. Where 10
The relationship between the distance and voltage after 10,000 round trips is represented by a graph,
The deviation from the ideal voltage value (ΔV and ΔV ′) is calculated, and the larger value (ΔVmax) of ΔV and ΔV ′ and the ideal voltage value (V) at that distance are used. The linearity is calculated from the following equation.

Linearity (%) = (△ Vmax / V) × 100 In the measurement of the linearity, specifically, as shown in FIG. 2, a voltage of 5 V is applied in a 9 cm direction of a sample cut into a 5 cm × 9 cm square. The voltage may be measured at 1 cm intervals, and the deviation from the ideal value (ΔV and ΔV ′) may be calculated.

Further, the transparent conductive film of the present invention is characterized in that the retardation value is 15 nm or less. The retardation value is calculated by calculating the difference (Δn) between the refractive index in the TD direction and the refractive index in the MD direction of the base film, and using the following equation.

Retardation (nm) = d × Δn That is, the retardation value is determined by the TD of the base film.
It is a value obtained by multiplying the difference between the refractive index in the MD direction and the refractive index in the MD direction by the thickness of the base film.

[0037]

The present invention will be described in more detail with reference to the following examples.

<Example 1> A film 1 was formed by a casting method.
00 µm thick polycarbonate film (Teijin Corporation)
A non-solvent type acrylic ester-based curable resin (manufactured by Nippon Zeon Co., Ltd., trade name: Quinbeam-7008) coated on both sides of a transparent polymer base material having a thickness of 10 μm,
Oxygen glow discharge treatment (1.3 Pa, 900 W, 1 minute)
Was given.

Next, the reaction gas was nitrogen / argon = 1.
Then, a layer made of silicon oxynitride having a thickness of 16 nm was formed by a DC magnetron sputtering method under an atmosphere of 0.5 Pa.

Continuously, using an indium tin alloy containing 20% by weight of tin as a target, a reaction gas was introduced at a ratio of argon / oxygen = 40, and a DC magnetron sputtering method was performed under an atmosphere of 0.4 Pa. A transparent conductive film of the present invention was produced by forming indium tin oxide to a thickness (20 nm) with a surface resistance of 500 Ω / □ to form a transparent conductive film layer.

<Example 2> Instead of the oxygen glow discharge treatment, a corona discharge treatment (applied voltage: 3.5 kV, speed: 3 m /
A transparent conductive film was prepared under the same conditions as in Example 1 except that the above steps were performed.

Example 3 An epoxy acrylate resin (trade name: TUR1776HV, manufactured by Teikoku Chemical Industry Co., Ltd.) was used in place of the acrylic ester-curable resin, and the thickness of the silicon oxynitride layer was 10 nm. A transparent conductive film was produced under the same conditions as in Example 1 except for the above.

Example 4 A transparent conductive film was produced under the same conditions as in Example 1 except that the thickness of the layer made of silicon oxynitride was 10 nm.

Example 5 A transparent conductive film was produced under the same conditions as in Example 1 except that the thickness of the layer made of silicon oxynitride was changed to 20 nm.

<Embodiment 6> After performing the glow discharge treatment,
A transparent conductive film was manufactured under the same conditions as in Example 1 except that a 1-nm-thick nickel-chromium alloy film was formed on the surface subjected to the glow discharge treatment before forming the layer made of silicon oxynitride.

Example 7 A transparent conductive film was produced under the same conditions as in Example 6, except that the thickness of the nickel-chromium alloy film was changed to 2 nm.

Example 8 A transparent conductive film was produced under the same conditions as in Example 1 except that the glow discharge treatment was not performed.

<Embodiment 9> The glow discharge condition was 650 W
(0.5 A, 1300 V)
Under the same conditions as above, a transparent conductive film was produced.

Example 10 A transparent conductive film was produced under the same conditions as in Example 1 except that the glow discharge gas was air.

Example 11 A transparent conductive film was produced under the same conditions as in Example 1 except that the reaction gas used for forming the silicon oxynitride layer was changed to nitrogen / argon = 2.

Example 12 A transparent conductive film was produced under the same conditions as in Example 1 except that the reaction gas used for forming the silicon oxynitride layer was changed to nitrogen / argon = 4.

Example 13 A transparent conductive film was produced under the same conditions as in Example 1 except that the transparent conductive film layer made of indium tin oxide was formed to have a surface resistance of 350 Ω / □. .

Comparative Example 1 A transparent conductive film was produced under the same conditions as in Example 1 except that the thickness of the layer made of silicon oxynitride was changed to 2 nm.

<Comparative Example 2> A transparent conductive film was produced under the same conditions as in Example 1 except that the reaction gas at the time of forming the silicon oxynitride layer was nitrogen / argon = 0.5. .

Comparative Example 3 The thickness of the transparent conductive film layer made of indium tin oxide was 5 nm, and the surface resistance value was 2 k.
A transparent conductive film was produced under the same conditions as in Example 1 except that the film was formed to have a resistance of Ω / □.

<Evaluation> The surface resistance, transmittance, writing characteristics (linearity), retardation value, adhesion, and alkali resistance of the transparent conductive films produced in each of the examples and comparative examples were evaluated by the following methods. . The evaluation results are shown in Table 1 below.

[Surface resistance (R, Ω / □)] Measured by a four-terminal method.

[Transmittance (Tvis,%)] The transmittance was measured using a spectrophotometer U-3500 manufactured by Hitachi, Ltd.

[Writing Characteristics (Linearity%)] As shown in FIGS. 1 and 2, an adhesive is provided on the transparent conductive film 3 and the polarizing film 5 with a hard coat is attached thereto.
The transparent conductive film 3 side was overlapped with the glass 1 with a conductive film provided with the spacer 2, and the linearity of the polarizing film 5 side of this sample was evaluated with a polyacetal pen. The sliding conditions were 250 g load, 100,000 reciprocations (3 reciprocations / 1 second,
(One-way distance 35 mm). Glass with conductive film 1
Is a SnO ₂ film, the material of the spacer 2 is an acrylic resin, the width is 100 μm, the height is 200 μm, and the adhesive 4
Was 20 μm, the hardness of the polarizing film 5 with a hard coat was 2 H or more, and the thickness was 180 μm.

After sliding 100,000 reciprocations, as shown in FIG.
A voltage of 5 V was applied in the 9 cm direction of the sample cut into a square of 9 cm square, the voltage was measured at 1 cm intervals, and the deviation from the ideal value (ΔV and ΔV ′) was calculated to determine the linearity.

[Retardation value] KOBRA-21ADH manufactured by Shin-Oji Paper Co., Ltd. according to the parallel Nicol rotation method.
Was used to calculate the difference in the refractive index between the TD direction and the MD direction of the base film, and this value was multiplied by the thickness of the base film to obtain a retardation value.

[Adhesion (gf / inch)] JIS K
According to 6854, the peeling was performed at 90 ° × 5 mm / min using Shimadzu Autograph AGS-100A. Generally, 50 gf / inch or more is a passing criterion.

[Alkali Resistance] The resistance change rate after immersion in 3.5% KOH for 3 minutes (23 ° C.) was measured, and (R / R 0) ≦
1.1 is defined as “◎”, and 1.1 <(R / R0) <1.3.
Was evaluated as “「 ”and 1.3 ≦ (R / R0) was evaluated as“ × ”.

[0064]

[Table 1]

[0065]

As described above, according to the present invention,
In particular, it is possible to provide a transparent conductive film for a touch panel excellent in writing resistance, alkali resistance and adhesion.

The transparent conductive film of the present invention has the above-mentioned excellent properties. For example, the transparent conductive film may be applied to a touch panel having a structure in which a transparent conductive film is provided under a polarizing plate of a liquid crystal display element in order to improve visibility. It can be used very effectively.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a state of measuring the linearity of a touch panel sample according to the present invention.

FIG. 2 is a schematic plan view showing a state of measuring the linearity of the touch panel sample of the present invention.

FIG. 3 is a graph for explaining a linearity measurement method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass with conductive film 2 Spacer 3 Transparent conductive film 4 Adhesive 5 Polarizing film with hard coat 6 Polyacetal pen 8 Sliding part 9 Electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuichiro Harada 2-1-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi Inside Mitsui Toatsu Chemicals Co., Ltd. (72) Akira Suzuki 2-chome Tango-dori, Minami-ku, Nagoya-shi, Aichi No. 1 Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Akemi Nakajima 2-1-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi Prefecture

Claims (6)

[Claims] 1. The linearity after 100,000 reciprocations (3 reciprocations / 1 second, one-way distance 35 mm) with a load of 250 g using a polyacetal pen having a diameter of 8 mm is 1.5% or less, and the retardation value is 15 nm. The following transparent conductive film for touch panels. 2. A transparent polymer substrate (A) having one main surface
The transparent conductive film for a touch panel according to claim 1, wherein a layer (B) made of silicon oxynitride and a transparent conductive film layer (C) made of indium tin oxide are sequentially laminated. 3. A main surface of the transparent polymer substrate (A) is subjected to a corona discharge treatment and / or a glow discharge treatment, and a layer (B) made of silicon oxynitride is laminated on the treated surface.
The transparent conductive film for a touch panel according to the above. 4. The method according to claim 1, wherein one of the main surfaces of the transparent polymer substrate (A) is
The transparent conductive film for a touch panel according to claim 2, wherein a metal thin film layer or a metal oxide thin film layer (D) mainly composed of nickel is laminated, and a layer (B) composed of silicon oxynitride is laminated on the layer (D). . 5. One of the main surfaces of the transparent polymer substrate (A) is subjected to a corona discharge treatment and / or a glow discharge treatment, and a metal thin film layer or a metal oxide thin film layer (D) mainly composed of nickel is formed on the treated surface. 3. The transparent conductive film for a touch panel according to claim 2, wherein a layer (B) made of silicon oxynitride is laminated on the layer (D). 6. A layer (B) made of silicon oxynitride having a thickness of 3
The transparent conductive film for a touch panel according to any one of claims 1 to 5, wherein the thickness is from 30 to 30 nm.