JPH09187877A - Transparent conductive resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive resin film provided with a transparent conductive film in which film quality such as transparency is not changed by alkali treatment and is chemically stable and both dispersion and change of resistance are hardly caused. SOLUTION: A transparent conductive film layer having a thickness of >=15nm is provided on a transparent resin film. The transparent conductive film layer consists of high resistance transparent conductive film having specific resistance of >=2×10<-3> Ω.cm and a thickness of 5-50nm and of low resistance transparent conductive film having specific resistance of <=1×10<-3> Ω.cm and a thickness of 5-50nm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transparent conductive resin film. More specifically, it relates to a transparent conductive resin film that can be suitably used as a film for a touch panel used for a liquid crystal display device, for example.

[0002]

2. Description of the Related Art In recent years, liquid crystal display elements have been drawing attention as image display elements, and are expected to be applied to, for example, portable electronic notebooks, portable information terminals and the like.

For example, as an input device such as the portable information terminal, there is one in which a transparent touch panel is mounted on a liquid crystal display element. A resistance type touch panel is generally used for the input device, particularly from the viewpoint of price, and as such a resistance type touch panel,
A film having a structure in which a transparent conductive film and a glass plate on which a transparent conductive film is formed are separated by an appropriate distance is widely used.

The transparent conductive film is, for example, 5 to 1
A sputtered film is used in which indium oxide added with about 0% by weight of tin oxide is formed at a low temperature near room temperature using a DC sputtering device. Such a sputtered film usually has a specific resistance of 5 × 10 ^−. It is about ⁴ Ω · cm.

Here, the following relationship is established among the specific resistance, sheet resistance and film thickness of the sputtered film (conductive film).

When the specific resistance is ρ, the sheet resistance is R, the area of the electrodes is A, and the distance between the electrodes formed on the same conductive film is x, the relation between them is as follows:

[0007]

[Equation 1]

The relationship expressed by Since the sheet resistance R of such a conductive film is not a resistance in the thickness direction but a resistance in the surface direction, the area A of the electrode is the product of the product of the electrode length l and the conductive film thickness t. It is represented by t. Therefore, among the sheet resistance R, the specific resistance ρ, the distance x between the electrodes, the length l of the electrodes, and the thickness t of the conductive film, the following equation is obtained:

[0009]

[Equation 2]

The relationship represented by That is,
The sheet resistance R of such a conductive film is proportional to the specific resistance ρ and inversely proportional to the thickness t.

Normally, a touch panel requires a large sheet resistance of about 500 Ω / □. When the sputtered film is used in such a touch panel, since the specific resistance of the sputtered film is about 5 × 10 ⁻⁴ Ω · cm as described above, a sheet resistance as large as described above is applied to the sputtered film. In order to be provided, the film thickness must be reduced to about 10 nm.

By the way, it is generally known that the vapor-deposited thin film such as the sputtered film usually has an extremely large electric resistance when the film thickness becomes very thin, about 5 nm or less. This is considered to be because in the case of a very thin film, a part of the film is discontinuous.

On the other hand, as used in a touch panel,
Since the film in the film thickness region having a thickness of about 0 nm is usually a continuous film, there is no problem regarding the resistance of the film as described above, but when a touch panel is manufactured using such a sputtered film, an alkali is used. It was revealed that the treatment caused a change in the film quality. Such a change in film quality is not observed when the film thickness is, for example, about 20 nm or more, and therefore is caused by the fact that the thickness of about 5 to 10 nm is the transition region from the discontinuous film to the continuous film. Presumed to be.

In order to eliminate the chemical instability of the sputtered film as described above, it is easily inferred that the film thickness should be increased to several tens of nm to form a completely continuous film. However, from the relationship between the sheet resistance, the specific resistance, and the film thickness, in order to increase the film thickness without reducing the sheet resistance, it is necessary to adjust the film forming conditions and increase the specific resistance of the film.

However, the specific resistance of the sputtered film is
It has become clear that when trying to make the specific resistance larger than that of itself, the dispersion of the specific resistance becomes extremely large, which adversely affects the original function of the touch panel.

That is, although it depends on the sputtering apparatus used, in general, if the ratio of oxygen to argon gas in the sputtering apparatus is in the range of 0.5 to 2% by weight, which is usually used, the oxygen content is reduced. The specific resistance of the sputtered film does not change significantly due to the change in the ratio, but when the ratio of oxygen to argon gas exceeds 3% by weight, the specific resistance is remarkably large even if the ratio of oxygen is slightly high. Change. Therefore, the specific resistance of the sputtered film is, for example, 2
When increasing the oxygen concentration to increase to about 10 ⁻³ Ω · cm, even if the oxygen concentration in the chamber slightly fluctuates, the specific resistance varies greatly.
In an extreme case, the specific resistance varies by one digit or more, and the sheet resistance of the conductive film also varies.

Therefore, the variation in resistance in the resistance type touch panel directly leads to a reduction in the position detection accuracy. Therefore, it is not possible to use a transparent conductive film having a large specific resistance for the touch panel in order to increase the film thickness. There's a problem.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above prior art, and is chemically stable without changing the film quality such as transparency due to the treatment with an alkali. An object of the present invention is to provide a transparent conductive resin film provided with a transparent conductive film that hardly causes variations and changes in resistance.

[0019]

The present invention provides a high-resistivity transparent conductive film having a specific resistance of 2 × 10 ⁻³ Ω · cm or more and a thickness of 5 to 50 nm and a specific resistance on a transparent resin film. 1 x 10
^A transparent conductive resin film having a transparent conductive film layer having a thickness of 5 nm or more and a low resistance transparent conductive film having a thickness of 5 nm to 50 nm, and having a thickness of 15 nm or more.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the transparent conductive resin film of the present invention has a high specific resistance of 2 × 10 ⁻³ Ω · cm or more and a thickness of 5 to 50 nm on the transparent resin film. Resistive transparent conductive film with a specific resistance of 1 × 10 ⁻³ Ω · cm or less,
A low-resistance transparent conductive film having a thickness of 5 to 50 nm is provided, and a transparent conductive film layer having a thickness of 15 nm or more is provided.

A major feature of the present invention is that a transparent conductive film layer having a specific thickness is provided on a transparent resin film, which is composed of two layers of a film exhibiting high resistance and a film exhibiting low resistance. There is one.

Although the sheet resistance of the transparent conductive film layer is about the same as the sheet resistance of the low resistance transparent conductive film, its thickness is the total thickness of the two kinds of transparent conductive films. Since at least one of the film exhibiting high resistance and the film exhibiting low resistance used for the film layer is a chemically stable and completely continuous film, the transparent conductive film is transparent by treatment with an alkali. The quality of the film does not change and it becomes chemically stable.

The sheet resistance of the entire transparent conductive film layer can be explained as follows, for example.

The sheet resistance R of the transparent conductive film layer is expressed by the following equation, where R ₁ is the sheet resistance of the low resistance transparent conductive film and R ₂ is the sheet resistance of the high resistance transparent conductive film.

[0025]

(Equation 3)

From the above equation,

[0027]

(Equation 4)

In this case, that is, when the difference between the sheet resistance R ₂ of the high resistance transparent conductive film and the sheet resistance R ₁ of the low resistance transparent conductive film is sufficiently large, the sheet resistance R of the high resistance transparent conductive film is large. _{Since 2} has almost no effect on the sheet resistance R of the entire transparent conductive film layer, the sheet resistance R is expressed by the formula:

[0029]

(Equation 5)

As represented by, the sheet resistance R ₁ of the transparent conductive film having a low resistance is substantially equal to the sheet resistance R ₁ .

On the other hand, the high-resistance transparent conductive film and the low-resistance transparent conductive film are films having substantially the same composition except that the oxygen concentration supplied during sputtering is slightly different. The layers have a substantially uniform chemistry.

As described above, the transparent conductive resin film of the present invention has a transparent conductive film layer having a two-layer structure of a high resistance transparent conductive film and a low resistance transparent conductive film, each having a specific thickness. Although the transparent conductive film layer is required for practical use and has a chemically stable thickness of 15 nm or more, for example, about 500 Ω / □ normally required for a touch panel used for a liquid crystal display device. It has a sheet resistance of.

The transparent conductive resin film of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing the structure of the transparent conductive resin film of the present invention.

As shown in FIG. 1, in the transparent conductive resin film of the present invention, a transparent conductive film layer 4 composed of a high resistance transparent conductive film 2 and a low resistance transparent conductive film 3 is formed on a transparent resin film 1. It is provided.

In FIG. 1, a transparent conductive resin in which a high resistance transparent conductive film 2 is formed on a transparent resin film 1 and a low resistance transparent conductive film 3 is further formed on the high resistance transparent conductive film 2. Although a film is shown, the order in which the high resistance transparent conductive film 2 and the low resistance transparent conductive film 3 are formed is not particularly limited, and contrary to FIG. The resistance transparent conductive film 3 may be formed, and the high resistance transparent conductive film 2 may be further formed on the low resistance transparent conductive film 3.

Transparent resin film 1 used in the present invention
Is preferably a resin film having physical properties such as heat resistance and impact resistance required for a film for a touch panel used in a liquid crystal display element, for example.

Examples of the transparent resin film 1 include polyarylate, polycarbonate, polysulfone,
Examples include films made of resins such as thermoplastic resins such as polyether sulfone, but the present invention is not limited to these examples.

Among these, a film made of polyarylate is particularly preferable because it has excellent heat resistance and excellent adhesion to the transparent conductive film layer 4. The polyarylate is not particularly limited, but those obtained by polycondensing terephthalic acid and / or isophthalic acid with a divalent phenol are preferable because the raw materials are easily available.

Specific examples of the dihydric phenol include:
For example, 2,2'-bis (4-hydroxyphenyl) propane, 4,4 '-(α-methylbenzylidene) bisphenol, bis (4-hydroxyphenyl) methane,
2,2'-bis (4-hydroxyphenyl) butane,
3,3'-bis (4-hydroxyphenyl) pentane,
4,4'-bis (4-hydroxyphenyl) heptane,
4,4'-bis (4-hydroxyphenyl) 2,5-dimethylheptane, bis (4-hydroxyphenyl) methylphenylmethane, bis (4-hydroxyphenyl) diphenylmethane, 2,2'-bis (4-hydroxyphenyl) ) Octane, bis (4-hydroxyphenyl) -4
-Fluorophenylmethane, bis (3,5-dimethyl-
4-hydroxyphenyl) methane, 2,2'-bis (3,5-dimethyl-4-hydroxyphenyl) propane, bis (3,5-dimethyl-4-hydroxyphenyl) phenylethane, bis (3-methyl-4) -Hydroxyphenyl) diphenylmethane, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, etc. Alternatively, two or more kinds may be mixed and used, but the present invention is not limited to these examples.

For example, the method of forming a resin such as the thermoplastic resin into a film is not particularly limited. For example, a method of extruding the resin using an ordinary extruder or a method of dissolving the resin in a solvent is used. Examples of the method include casting a solution, and the casting method is more preferable because the thickness of the obtained film can be made more uniform.

The thickness of the transparent resin film 1 thus obtained is not particularly limited, but usually 10 to 200 in consideration of the use of the finally obtained transparent conductive resin film.
It is desirable that the thickness is μm, preferably 40 to 100 μm.

By forming the transparent conductive film layer 4 on the transparent resin film 1 as described above, the transparent conductive resin film of the present invention can be obtained.

As described above, the transparent conductive film layer 4 is formed by laminating the high resistance transparent conductive film 2 and the low resistance transparent conductive film 3.

The transparent conductive film layer 4 may be made of a metal oxide such as indium oxide, tin oxide, or a composite oxide of indium oxide and tin oxide. It is particularly preferable to use indium oxide or a composite oxide of indium oxide and tin oxide from the viewpoint of high cost.

In the present invention, the high resistance transparent conductive film 2 and the low resistance transparent conductive film 3 may be made of the same metal oxide or may be of different types. There is no limit.

The method for forming the transparent conductive film layer 4 is not particularly limited and, for example, a vacuum vapor deposition method, a sputtering method, an ion plating method or the like can be adopted. Resin film 1
The sputtering method is particularly preferable from the viewpoint of high adhesiveness with.

The transparent conductive film layer 4 is preferably formed by the sputtering method at room temperature to about 100 ° C. while flowing an inert gas such as argon gas containing oxygen.

In the present invention, the heat resistance of the transparent resin film 1 can be improved by forming the transparent conductive film layer 4 at a film forming temperature of 100 ° C. or lower by the DC magnetron sputtering method using a DC magnetron sputtering device. It is preferable for consideration.

The high resistance transparent conductive film 2 and the low resistance transparent conductive film 3 forming the transparent conductive film layer 4 can be respectively formed by appropriately adjusting film forming conditions such as oxygen concentration.

For example, when the conductive film is formed, the ratio of oxygen to argon gas in the sputtering apparatus is set to about 0.5 to 2% by weight, and the optimum film forming conditions are set so that the conductivity is maximized. , The specific resistance is 1 × 10 ^-3
When a conductive film having a resistance of Ω · cm or less is used as a more optimal film forming condition, a conductive film having a specific resistance of about 5 × 10 ⁻⁴ Ω · cm and a small resistance distribution, that is, a low-resistance transparent conductive film 3 Can be formed. On the contrary, when the conductive film is formed, the ratio of oxygen to the argon gas in the sputtering apparatus is set to about 3% by weight or more so as to deviate from the optimum conditions, so that the specific resistance is 2 × 10 ^{−. 3} Ω
A conductive film of cm or more, that is, the high resistance transparent conductive film 2 can be formed.

The specific resistance of the high resistance transparent conductive film 2 thus formed is 2 × 10 ⁻³ Ω · cm or more, but the sheet resistance of the high resistance transparent conductive film 2 is the sheet resistance of the entire transparent conductive film layer 4. 5x to reduce the impact on
It is preferably 10 ⁻³ Ω · cm or more. The upper limit of the specific resistance of the high resistance transparent conductive film 2 is not particularly limited.

Further, the thickness of the high resistance transparent conductive film 2 is a region where the entire thickness of the transparent conductive film layer 4 is chemically stable.
In order to make it 5 nm or more, 5 nm or more, preferably 1
0 nm or more, and 50 nm or less, preferably 4 nm or less in order to further reduce the influence of the sheet resistance of the high resistance transparent conductive film 2 on the sheet resistance of the entire transparent conductive film layer 4.
0 nm or less.

The low resistance transparent conductive film 3 has a resistance distribution in consideration of the fact that the sheet resistance of the low resistance transparent conductive film 3 has a great influence on the sheet resistance of the entire transparent conductive film layer 4 as described above. The specific resistance is 1 × 10 ⁻³ Ω · c under the optimum film formation conditions that produce few and good reproducibility.
m or less, preferably within the range of the minimum value of about 5 × 10 ⁻⁴ Ω · cm.

The thickness of the low resistance transparent conductive film 3 may be adjusted so that the transparent conductive film layer 4 has a desired sheet resistance in consideration of its specific resistance, and it is 5 nm or more, preferably 10 nm or more. And 50 nm or less, preferably 40
nm or less.

The thickness of the low resistance transparent conductive film 3 is
It is determined from the total thickness of the transparent conductive film layer 4 and the thickness of the high resistance transparent conductive film 2, and is 5 nm or more in consideration of the function of the conductive film itself.

Further, when the obtained transparent conductive resin film is used as a film for a touch panel, for example, the sheet resistance of the transparent conductive film layer 4 is 300Ω / □.
Considering that the above is desirable and the sheet resistance of the transparent conductive film layer 4 is greatly affected by the sheet resistance of the low resistance transparent conductive film 3, for example, the specific resistance of the low resistance transparent conductive film 3 is 1 or less. When it is × 10 ^-3 Ω · cm, the film thickness may be about 33 nm or less.

The total thickness of the transparent conductive film layer 4 composed of the high resistance transparent conductive film 2 and the low resistance transparent conductive film 3 is chemically stable, and there is no fear of becoming a discontinuous film. 15n in order to obtain the desired sheet resistance.
m or more, preferably 20 nm or more, and the total thickness of the transparent conductive film layer 4 is 100 nm or less.

Further, the sheet resistance of the transparent conductive film layer 4 is
As described above, when the sheet resistance of the high resistance transparent conductive film 2 is sufficiently larger than the sheet resistance of the low resistance transparent conductive film 3, the sheet resistance of the low resistance transparent conductive film 3 should be approximately the same. In consideration of the fact that the sheet resistance of the high resistance transparent conductive film 2 is 7 times or more than the sheet resistance of the low resistance transparent conductive film 3,
It is preferably 10 times or more.

As described above, the transparent conductive resin film of the present invention has a specific thickness composed of two types of transparent conductive films 2 and 3 each having a specific resistivity and a specific thickness on the transparent resin film 1. Since the transparent conductive film layer 4 is provided, it is chemically stable as compared with the conventional conductive resin film in which a single transparent conductive film is provided on the resin film, and variations and changes in resistance are caused. Rarely occurs.

[0061]

EXAMPLES Next, the transparent conductive resin film of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 A composite oxide of indium oxide and tin oxide (indium oxide containing 10% by weight of tin oxide) was used as a target on a transparent polyarylate film having a thickness of 75 μm, and 5% by weight of oxygen was added. In an argon gas atmosphere
A thickness of 10 n is obtained by a DC magnetron sputtering method using a DC magnetron sputtering device at 50 ° C.
m high resistance transparent conductive film (sputtered film) was formed.

The sheet resistance of the formed high resistance transparent conductive film was measured by using a sheet resistance measuring film (Loresta AP manufactured by Mitsubishi Yuka Co., Ltd.) with a film for resistance monitoring which was separately placed in a DC magnetron sputtering device. It was 5000-10000 ohms / square when it measured using. The specific resistance of the high resistance transparent conductive film calculated from the sheet resistance and the thickness was 5 × 10 ⁻³ to 1 × 10 ⁻² Ω · cm.

Next, a film having a thickness of 15 nm is formed on the high resistance transparent conductive film under the same film forming conditions as the high resistance transparent conductive film except that sputtering is performed in an argon gas atmosphere containing 1% by weight of oxygen. The transparent conductive resin film was obtained by forming the low resistance transparent conductive film of

The sheet resistance of the formed low resistance transparent conductive film (sputtered film) was measured in the same manner as the sheet resistance of the high resistance transparent conductive film, and it was 500 ± 10 Ω / □. The specific resistance of the low resistance transparent conductive film calculated from the sheet resistance and the thickness was about 7.5 × 10 ⁻⁴ Ω · cm.

The sheet resistance of the entire transparent conductive film layer formed on the polyarylate film was 500 Ω / □, which was almost the same as the sheet resistance of the low resistance transparent conductive film.

Next, the obtained transparent conductive resin film was used and its alkali resistance was examined according to the following method. Table 1 shows the results.

(Alkali resistance) The transparent conductive resin film was immersed in a 2.5% aqueous sodium hydroxide solution heated to 40 ° C. for 5 minutes and then washed with running water.

The appearance of the transparent conductive resin film after washing was visually observed, and the sheet resistance of the transparent conductive film layer was measured in the same manner as above.

Comparative Example 1 In Example 1, the high resistance transparent conductive film was not formed,
A transparent conductive resin film was obtained in the same manner as in Example 1 except that only the low-resistance transparent conductive film having a thickness of 15 nm was formed on the polyarylate film.

The sheet resistance of the formed low-resistance transparent conductive film was measured in the same manner as in Example 1 to find 540 ± 10.
Ω / □. The specific resistance of the low resistance transparent conductive film calculated from the sheet resistance and the thickness is about 8.1 × 10 ⁻⁴ Ω.
Cm.

Next, the obtained transparent conductive resin film was used, and its alkali resistance was examined in the same manner as in Example 1. Table 1 shows the results.

In Table 1, the appearance of the transparent conductive resin film before the alkali resistance test and the sheet resistance of the transparent conductive film layer are shown together.

[0074]

[Table 1]

From the results shown in Table 1, the transparent conductive resin film of Comparative Example 1 in which only the low resistance transparent conductive film was formed lost its transparency and became cloudy after the alkali treatment. In addition to the appearance change that occurs, the sheet resistance of the transparent conductive film rises remarkably, whereas the transparent conductive film layer including the high resistance transparent conductive film and the low resistance transparent conductive film is formed in Example 1. It can be seen that the transparent conductive resin film (1) does not lose its transparency even after being subjected to the alkali treatment and the sheet resistance of the transparent conductive film layer hardly increases.

[0076]

EFFECTS OF THE INVENTION The transparent conductive resin film of the present invention does not change the film quality such as transparency due to the treatment with alkali, is chemically stable, and hardly causes variations and changes in resistance. A transparent conductive film is provided.

Therefore, the transparent conductive resin film of the present invention can be preferably used as a film for a touch panel used for a liquid crystal display device, for example.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of a transparent conductive resin film of the present invention.

[Explanation of symbols]

 1 transparent resin film 2 high resistance transparent conductive film 3 low resistance transparent conductive film 4 transparent conductive film layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C23C 14/08 C23C 14/08 N

Claims (5)

[Claims] 1. A specific resistance of 2 × 1 on a transparent resin film.
A high resistance transparent conductive film having a thickness of 5 to 50 nm and a resistance of 0 ^-3 Ω · cm or more, and a low resistance transparent conductive film having a specific resistance of 1 × 10 ^-3 Ω · cm or less and a thickness of 5 to 50 nm. Consists of 1 thickness
A transparent conductive resin film provided with a transparent conductive film layer having a thickness of 5 nm or more. 2. The transparent conductive resin film according to claim 1, wherein the sheet resistance of the high resistance transparent conductive film is 7 times or more the sheet resistance of the low resistance transparent conductive film. 3. The transparent conductive resin film according to claim 1, wherein the transparent resin film is a film made of polyarylate. 4. The transparent conductive resin film according to claim 1, wherein the transparent conductive film layer is made of indium oxide or a composite oxide of indium oxide and tin oxide. 5. The transparent conductive resin film according to claim 1, 2, 3 or 4, wherein the transparent conductive film layer is formed by a DC magnetron sputtering method at a film forming temperature of 100 ° C. or lower.