JP5572932B2 - Transparent conductive film and touch panel - Google Patents

Description

  The present invention relates to a transparent conductive film useful as a transparent electrode, a touch panel, and an electromagnetic wave shielding film.

  Transparent conductive films have the property of having both conductivity and optical transparency, and are therefore used industrially as transparent electrodes, electromagnetic shielding films, planar heating films, antireflection films, etc. In recent years, it has attracted attention as an electrode for touch panels.

There are various types of touch panels such as a capacitive coupling type and an optical type. Among them, the transparent conductive film is used in a resistive film type in which a touch position is specified by contact between upper and lower electrodes and a capacitive coupling method in which a change in capacitance is detected. In particular, the former can be used for pen input and is relatively inexpensive, and thus is widely used for portable terminals, portable game machines, and the like. In this method, contact between conductive films is not avoided on the principle of operation, and therefore, in order to extend the hit point life of the touch panel, development of a transparent conductive film having high hit point durability has been advanced.
Further, since it is used as an external display, high light transmission is desired.
In addition, as said background art document, the following patent document 1 is mentioned.
Japanese Patent No. 4086132

  Due to the thin frame of liquid crystal panels and the diversification of usage environments, high durability of touch panels incorporated in displays is required. For that purpose, high durability of the transparent conductive film used as an electrode is indispensable.

  An object of the present invention is to provide a transparent conductive film and a touch panel that improve the pen writing durability and also improve the light transmittance.

The invention according to claim 1 is a transparent conductive film in which a transparent conductive film is provided on at least one surface of a transparent substrate.
In order from the transparent base material, the transparent conductive film is formed by laminating an adhesion layer, a first ITO layer that is an amorphous film, and a second ITO layer that is a crystallized film,
The refractive index n1 of the first ITO layer and the refractive index n2 of the second ITO layer satisfy the relationship of n1> n2 ,
The adhesion layer is made of silicon oxide formed by a direct current magnetron sputtering method having a thickness of 5 to 30 nm , and
The transparent conductive film is characterized in that the total thickness of the first ITO layer and the second ITO layer is 10 nm or more and 50 nm or less .
In the invention according to claim 2 , the tin content of the first ITO layer is 5 wt% to 20 wt%, and the tin content of the second ITO layer is 1 wt% to 4 wt%. The transparent conductive film according to claim 1 .
The invention described in claim 3 is a touch panel using the transparent conductive film described in claim 1 or 2 .

  ADVANTAGE OF THE INVENTION According to this invention, while improving pen-writing durability, the transparent conductive film and touch panel which also improve light transmittance can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the embodiments, the same components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a cross-sectional view of an embodiment of the transparent conductive film of the present invention. In FIG. 1, a transparent conductive film 1 includes an adhesive layer 3 on one surface of a transparent substrate 2, a first ITO layer 4 a that is an amorphous film on the adhesive layer 3, and a crystallized film on the ITO layer 4 a. The second ITO layer 4b is provided.

  The transparent conductive film 1 according to the embodiment of the present invention includes a first ITO layer 4a that is an amorphous film, and a second ITO layer 4b that is a crystallized film thereon. By providing the second ITO layer 4b, which is a crystallized film, on the first ITO layer 4a, which is an amorphous film, pen writing durability and light transmission when the transparent conductive film 1 is mounted on a touch panel Can increase the sex.

  In particular, the durability can be improved by providing the touch panel with the second ITO layer 4b which is a crystallized film.

  In the present invention, the relationship between the refractive index n1 of the first ITO layer 4a, which is an amorphous film, and the refractive index n2 of the second ITO layer 4b, which is a crystallized film, must be n1> n2. There is. By satisfying this relationship, the transmittance can be improved.

  In the present invention, the total thickness of the first ITO layer 4a, which is an amorphous film, and the second ITO layer 4b, which is a crystallized film, is preferably 10 nm to 50 nm. If the film thickness of the transparent conductive film is less than 10 nm, film formation control may not be performed satisfactorily. If it exceeds 50 nm, the resistance value becomes too low, and the detection performance as a touch panel may be deteriorated.

  Further, the transparent conductive film 1 includes an adhesion layer 3 between the transparent substrate 2 and the first ITO layer 4a which is an amorphous film. By providing the adhesion layer 3, the adhesion of the transparent conductive film 1 is improved, and pen writing durability when mounted on the touch panel can be enhanced.

  The material of the transparent substrate 2 includes polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6 and nylon 66; polyimides; polyarylate; polycarbonate; Ether sulfone, polysulfone, and unstretched or stretched plastic films of these copolymers can be used. Also, other plastic films with high transparency can be used. The thickness is about 10 to 200 μm in consideration of the flexibility of the substrate. Of these, polyethylene terephthalate is preferably used.

  As these transparent base materials 2, those in which a primer layer such as a hard coat is laminated on one or both surfaces are preferably used.

  These transparent base materials 2 may be subjected to surface treatment such as easy adhesion treatment, plasma treatment, and corona treatment.

  As a material for forming the adhesion layer 3, a metal or an inorganic compound such as an oxide, sulfide or fluoride thereof can be used. Practically, silicon oxide, aluminum oxide, etc. are particularly preferably used.

  The thickness of the adhesion layer 3 is preferably 5 to 30 nm. When the film thickness is less than 5 nm, it becomes difficult to obtain film uniformity, and when the film thickness exceeds 30 nm, transparency is lowered.

  The conductive materials of the ITO layers 4a and 4b can contain additives such as Al, Zr, Ga, Si, and W as necessary.

  The method for producing the adhesion layer 3 and the ITO layers 4a and 4b according to the present invention is not particularly limited. it can. In addition, after forming the 1st ITO layer 4a and the 2nd ITO layer 4b, the 2nd ITO layer 4b can be crystallized by heating at 150 to 200 degreeC for 1 hour or more.

In the present invention, the tin content of the first ITO layer 4a that is an amorphous film is 5 wt% to 20 wt%, and the tin content of the second ITO layer 4b that is a crystallized film is 1 wt%. It is preferably ˜4% by weight.
When the tin content of the ITO layer 4a is 5 wt% to 20 wt%, good durability can be imparted, and at the same time, the tin content of the ITO layer 4b is 1 wt% to 4 wt% Good transmittance can be obtained.

  As shown in FIG. 4, the touch panel 10 according to the embodiment of the present invention includes a hard coat layer 5 on both sides of the transparent substrate 2, an adhesion layer 3 on one hard coat layer 5, and an adhesion layer 3. A transparent conductive film 1 having a first ITO layer 4a which is an amorphous film, and a second ITO layer 4b which is a crystallized film thereon, and a second crystallized film of the transparent conductive film 1 A transparent conductive film 6 and a substrate 7 are provided to face the ITO layer 4b with a spacer 8 therebetween.

  The transparent conductive film 1 which concerns on embodiment of this invention can be used suitably for the touch panel of a resistance film system among touch panels. The resistive film type touch panel 10 includes a transparent conductive layer 6 and a substrate 7 so as to face the transparent conductive film 4 of the transparent conductive film 1 according to the embodiment of the present invention. The transparent conductive film 4 and the transparent conductive layer 6 are kept away from each other by the spacer 8. The hard coat layer 5 side of the transparent conductive film 1 becomes the front surface of the touch panel 10, and characters and the like are input by the pen 9.

  In the touch panel 10 according to the embodiment of the present invention, when the pen 9 and the hard coat layer 5 are not touched, the two electrodes (the transparent conductive film 4 and the transparent conductive layer 6) are in contact with each other by the spacer 8. Current does not flow. On the other hand, when the hard coat layer 5 is touched with the pen 9, the transparent conductive film 1 bends due to the pressure, and contacts with the electrode (transparent conductive layer 6) on the substrate 7 (glass surface) side, and a current flows. At this time, the position inputted by the pen can be detected by measuring the voltage division ratio due to the resistance between the transparent conductive film 1 of the transparent conductive film 4 and the transparent conductive layer 6 of the substrate 7.

  Since the material for the transparent conductive film 1 has been described above, the material for the substrate 7 and the transparent conductive layer 6 will be omitted. The material of the substrate 7 is not limited to glass and can be used as long as it is transparent. Further, the same material and the same forming method as those of the transparent substrate 2 described above can be used. As the conductive material of the transparent conductive layer 6, oxides such as indium oxide, tin oxide, and zinc oxide and mixed oxides thereof can be used, and the same manufacturing method as the transparent conductive film 4 of the transparent conductive film 1 is used. Can be used. The film thickness can be arbitrarily selected from 10 nm to 50 nm as long as the uniformity of the film is not lost.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Example 1
A transparent conductive film 1 having the layer structure of FIG. 1 was prepared. A PET film having a thickness of 188 μm with a hard coat applied on both sides was used as a transparent substrate 2, and an adhesion layer 3 was formed on one surface of the transparent substrate 2 by direct current magnetron sputtering. At this time, silicon oxide was used for the adhesion layer 3. The film thickness was 10 nm.

  A first ITO layer 4a that is an amorphous film was formed on the adhesion layer 3 by direct current magnetron sputtering. At this time, ITO containing 10% by weight of tin oxide was used as a sputtering target. The film thickness was 10 nm.

  A second ITO layer 4b, which is a crystallized film, is formed on the first ITO layer 4a, which is an amorphous film, by a direct current magnetron sputtering method. At this time, ITO containing 3% by weight of tin oxide was used as a sputtering target. The film thickness was 10 nm.

Example 2
A transparent conductive film 1 having the layer structure of FIG. 2 was prepared. That is, the first ITO layer 4a, which is an amorphous film, was formed in the same manner as in Example 1 except that the first ITO layer 4a was formed directly on the transparent substrate 2. The second embodiment is a reference example.

Comparative Example 1
A transparent conductive film 1 having the layer structure of FIG. 3 was prepared. That is, a 188 μm-thick PET film coated with a hard coat on both sides is used as a transparent substrate 2, and an amorphous transparent conductive film 4 is formed on one side thereof by direct current magnetron sputtering. did. At this time, ITO containing 10% by weight of tin oxide was used as a sputtering target. The film thickness was 20 nm.

  About the above Example and the comparative example, the permeation | transmission characteristic and resistance value were measured. Moreover, as shown in FIG. 4, the touch panel 10 was formed and pen writing durability was evaluated. The pen 9 is a pen with a pen tip radius of 0.8mm made of polyacetal. From the upper surface of the hard coat layer, 250g weight is applied by a plotter, and 100,000 katakana characters from A to N are written. Measurements were made. The results are shown in Table 1.

  The transmission characteristics were measured with a spectrophotometer in a 2-degree field of D65 light source.

  The resistance value was measured by the four probe method.

  For linearity, 5V was applied between the electrodes, the voltage value at each point was measured, and the deviation from the ideal value (linearity) was calculated.

[Table 1]

  From the results shown in Table 1, it can be seen that Examples 1 and 2 having two ITO layers having different crystallinities are superior to Comparative Example 1 in light transmittance and pen writing durability. Moreover, it turns out that Example 1 which has an adhesion layer is further excellent in pen-writing durability compared with Example 2 which does not have an adhesion layer.

It is sectional drawing of one Embodiment of the transparent conductive film of this invention. It is sectional drawing of one Embodiment of the transparent conductive film of this invention. It is sectional drawing of the transparent conductive film of a comparative example. It is sectional drawing of one Embodiment of the touchscreen of this invention.

Explanation of symbols

1 Transparent conductive film
2 Transparent substrate
3 Adhesive layer
4 Transparent conductive film
4a The first ITO layer is an amorphous film
4b Second ITO layer as crystallized film
5 Hard coat layer
6 Transparent conductive layer
7 Base material
8 Spacer
9 pen
10 Touch panel

Claims (3)

In the transparent conductive film provided with a transparent conductive film on at least one surface of the transparent substrate,
In order from the transparent base material, the transparent conductive film is formed by laminating an adhesion layer, a first ITO layer that is an amorphous film, and a second ITO layer that is a crystallized film,
The refractive index n1 of the first ITO layer and the refractive index n2 of the second ITO layer satisfy the relationship of n1> n2 ,
The adhesion layer is made of silicon oxide formed by a direct current magnetron sputtering method having a thickness of 5 to 30 nm , and
The transparent conductive film, wherein a total thickness of the first ITO layer and the second ITO layer is 10 nm or more and 50 nm or less . The tin content of the first ITO layer is 5 wt% to 20 wt%, the tin content of the second ITO layer according to claim 1, characterized in that a 1% to 4% Transparent conductive film. A touch panel using the transparent conductive film according to claim 1 .

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