JP3366864B2 - Transparent conductive film - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transparent conductive film used for a touch panel or the like.

[0002]

2. Description of the Related Art In portable information terminals represented by personal digital assistants (PDAs) and sub-notebook computers, portability and ease of use are generally important, so that they are displayed on a display device such as a liquid crystal display. For example, a resistive touch panel is arranged as an input device. Then, by pressing the touch panel with a finger or a pen, an input is made, and the pressed position is confirmed as XY coordinates.

By the way, the touch-side substrate on which the input operation of the resistive film type touch panel is carried out has a film-like transparent polyethylene terephthale film having a photo-curing acrylic resin layer formed on one or both sides for the purpose of surface protection. Talate or polycarbonate is used, while polyethylene terephthalate, polycarbonate, soda lime glass or tempered glass is used for the display side substrate. Then, on one surface of each substrate, indium tin oxide (hereinafter referred to as ITO) is formed as a transparent conductive layer.
Thin film is formed.

[0004]

The touch panel has a high transparency in the visible light region (especially, a wavelength of 550).
(a high light transmittance in the vicinity of nm) is required. For this, a film forming the conductive layer on the touch side and a film forming the conductive layer on the display side and the transparent conductive layer are provided. A technique for inserting an appropriate metal oxide (hereinafter, referred to as “undercoat layer”) is known. That is, for example, a silicon oxide or silicon oxide-tin oxide-based metal oxide layer is inserted between each substrate and the transparent conductive layer, and the electrodes, the metal oxide layer, the film, and the refractive index are alternately changed. The technology is designed to improve transparency. Although not described in detail, this technique is extremely significant because the fact that the reflectance of light increases in the touch panel, particularly in the portion in contact with air, is a major factor of reducing the light transmittance.

By the way, here, the adhesion between the undercoat layer and the film substrate becomes a problem.

[0006] Therefore, an object of the present invention is to provide a transparent conductive film used for a touch panel or the like having excellent adhesion between the undercoat layer and the film substrate.

In order to achieve the above object, the transparency of the present invention
The conductive film, a conductive layer forming film, a conductive layer,
Consists of a metal oxide formed between the conductive layer-forming film and the conductive layer, and also consists of two layers with different optical properties
Layer, before providing the light transmittance of the entire transparent conductive film and
Undercoat layer for improving the conductivity (having conductivity
And a single metal element contained in the metal oxide formed between the undercoat layer and the conductive layer forming film, or two or more kinds containing at least one kind contained in the metal oxide. And a metal layer made of an alloy of the above metal elements.

This makes it possible to improve the adhesion between the undercoat layer and the conductive layer forming film and prevent the conductive layer from falling off.

The metal layer is preferably made of a metal selected from the group consisting of silicon, titanium, tin and zinc.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION [Embodiment] An embodiment in which the transparent conductive film according to the present invention is applied to a touch panel will be specifically described below.

* Regarding Configuration FIG. 1 is an exploded view showing the structure of the touch panel 1 according to the embodiment, and FIG. 2 is a sectional view taken along the line XX after assembly.

The touch panel 1 is a resistive film type touch panel, and as shown in FIG.
The display-side substrate 20 and the display-side substrate 20 are arranged so as to face each other in a state of forming an air layer 31 via a spacer 30.

The touch side substrate 10 is a planar member on the side of the touch panel 1 that receives an input from an operator using a finger or a device, and is made of a material having excellent flexibility and heat resistance and high transparency. , Hard coat layer 11 on both sides
And the conductive layer forming member 12 formed with the undercoat layer 13 formed on the one surface 11a of the hard coat layer 11 via the undercoat layer 13, and the undercoat layer 13 and the conductive layer 14. It is composed of an adhesion layer 15 that adheres to the layer forming member 12. Two facing conductive layers 14
Electrodes 141 and 142 are provided on the sides. Then, connector electrodes 143, 144 to which a connector (not shown) is connected are formed at the ends of the conductive layer forming member 12, and the connector electrodes 143, 144 and the electrode 14 are formed.
The wiring patterns 145 and 146 are connected between the first and the second wirings 142.

The display side substrate 20 is formed on a support member 22 having hard coat layers 21 formed on both sides thereof, and a conductive layer forming member 23 and an undercoat layer 24 on one surface 21a of the hard coat layer 21. The conductive layer 25 located in the central portion of the panel and the adhesion layer 26 that adheres the undercoat layer 24 and the conductive layer forming member 23 to each other.
The conductive layer forming member 23 is adhered to the surface of the hard coat layer 21 via the adhesive layer 27. The electrodes 1 formed on the conductive layer 14 on the two opposite sides of the conductive layer 25.
Electrodes 251 and 252 are formed on the sides of 41 and 142 in the direction orthogonal to the facing direction. Then, a pair of connector electrodes 253 and 254, which are connected to the connector, are formed at the end portions of the conductive layer forming member 23, and further, the connector electrodes 253 and 254 and the electrode 25 are formed.
Wiring patterns 255 and 256 for connecting 1 and 252 are formed. Further, on the surface of the conductive layer 25, for example,
Dot-shaped spacer 3 made of photocurable acrylic resin
Zeros (height: about 10 μm, diameter: 10 to 50 μm) are arranged at predetermined intervals (several mm intervals).

The touch-side substrate 10 and the display-side substrate 20 are bonded to each other by an adhesive 40 at their peripheral portions in a state where the conductive layers 14 and 25 face each other in parallel.

* About the hard coat layer The hard coat layer is formed by applying a photo-curing type silicone, acrylic, cellulose, melamine or urethane type resin to the base material (conductive layer forming member 12, support member 22). Then
Then, a thin layer having a thickness of several μm is formed by irradiating with ultraviolet rays and attaching the entire surface.

The hardness of the surface of the conductive layer forming member 12 on which the hard coat layer 11 is formed is determined by a pencil hardness measuring method from the viewpoint of durability against friction, adhesion of the transparent conductive layer, and appropriate rigidity to the conductive layer. It is preferably H or more and 3
More than H is more preferable.

It is preferable to provide the hard coat layer 11 because the durability of the panel itself is improved, but it is not necessary to provide it.

Also, such a hard coat layer can be formed on the surface of the conductive layer forming member 23.

* About the conductive layers 14 and 25 The conductive layers 14 and 25 are transparent and conductive metal oxides. The conductive layers 14 and 25 have ITO,
Indium oxide, antimony-added tin oxide, fluorine-added tin oxide, aluminum-added zinc oxide, potassium-added zinc oxide, silicon-added zinc oxide, or zinc oxide-tin oxide system,
Indium oxide-tin oxide-based and zinc oxide-indium oxide-magnesium oxide-based metal oxides can be used.

The pattern in which the conductive layers 14 and 25 are located in the central portion of the panel has a pattern of the undercoat layers 13 and 2.
4 is formed by wet etching after forming a conductive film on the entire surface.

Next, the electrodes 141, 142, 1 are formed by coating printing using a silver ink or a mixed ink of silver and carbon.
43, 144, 251, 252, 253, and wiring patterns 145, 146, 255, 256 are formed.

* Undercoat layers 13 and 24, adhesion layer 1
5 and 26, the undercoat layer 13 (24) is the conductive layer 14 (25)
Two insulating layers 13a (24a) and 13b (24) made of metal oxides having different refractive indices in the order of
b). Here, the conductive layer and the undercoat layer (upper and lower two layers) have higher refractive indexes in order,
It is designed to be low and high so that the light transmittance of these laminated structures is higher.

The layer 13b (24b) is the adhesion layer 15 (2
6) via the hard coat layer 11 (conductive layer forming member 2).
It is in close contact with 3). The adhesion layer 15 (26) is a metal layer composed of a single metal element or an alloy of two or more metal elements, and is preferably formed of a single element of silicon, titanium, tin or zinc, or an alloy thereof. .

The thickness of the adhesion layers 15 and 25 is preferably thinner than the adhesion layer made of silicon oxide (SiO _x ; X≤2) which has been generally used in the past, and is preferably set to 10Å to 50Å. This is because if it exceeds 50 Å, the light transmittance is lowered, and the significance of interposing the undercoat layer is lost. On the other hand, if it is less than 10 Å, sufficient adhesion cannot be obtained.

The adhesion layers 15 and 26 can be formed by applying a vacuum thinning technique such as a conventional general sputtering method, resistance vapor deposition method, electron beam vapor deposition method.

The metal oxides forming the undercoat layers 13 and 24 include silicon oxide, titanium oxide, tin oxide, tin oxide-hafnium oxide type, silicon oxide-tin oxide type, and
A zinc oxide-tin oxide type, a tin oxide-titanium oxide type, or the like can be used. By providing such layers having different refractive indexes, the light transmittance of the panel itself can be further improved.

The undercoat layers 13 and 24 can also be formed by applying a vacuum thinning technique such as a sputtering method, a resistance vapor deposition method, an electron beam vapor deposition method or the like, but an oxide of two or more kinds of metals can be formed by the sputtering method. When forming each of the undercoat layers 13 and 24 composed of, the sputtering efficiency is improved when an alloy of these metals is used as a raw material than when a simple substance of those metals is used as a raw material for sputtering. When set to, it is desirable because productivity is improved.

* About Adhesive Layer 27 The adhesive layer 27 is a thin layer made of a mixture of an adhesive and a plasticizer and having a predetermined thickness (for example, 5 to 100 μm). Examples of the adhesive include a rubber-based adhesive, an acrylic-based adhesive,
A silicone adhesive or the like can be used.

When an input operation by pressing is performed, the pressing is also transmitted to the conductive layer 25 on the display side, and a part of the conductive layer 25 is elastically deformed into a concave shape. If this elastic deformation is repeated, in the worst case, the restorability of the conductive layer itself is lost. In this case, the recess remains on the surface of the conductive layer 25, and the input operation using the touch panel cannot be performed properly. Here, the adhesive layer 27 plays a role of imparting elasticity to the conductive layer 25 and contributes to avoiding such a problem.

* Conductive Layer Forming Member 12, Support Member 22, and Conductive Layer Forming Member 23 The conductive layer forming members 12 and 23 include polyolefin resin, polycarbonate resin, acrylic resin such as polymethylmethacrylate, and polyethylene terephthalate. A transparent sheet made of such materials as described above can be used.

As the support member 22, a glass substrate, an acrylic resin substrate such as polycarbonate or polymethylmethacrylate, or a polyolefin resin substrate can be used.

However, considering impact resistance and lightness due to dropping, it is preferable to use an acrylic resin such as polycarbonate or polymethylmethacrylate, polyethylene terephthalate or a polyolefin resin substrate, and also considering heat resistance. Polycarbonate and polyolefin resin are more preferable.

* The reason why the adhesion between the undercoat layer and the hard coat layer and the conductive layer forming member is improved. If the adhesion layer is made of a metal such as silicon as described above, the adhesion layer has a reactivity due to the metal. Since the metal layer itself remains reactive even after formation, it chemically bonds with the undercoat layer, the hard coat layer and the conductive layer forming member with which the metal layer contacts. This is the same whether it is a single metal element or an alloy composed of a plurality of metal elements. On the other hand, in the case of conventional silicon oxide, the adhesion layer itself has poor reactivity. Therefore, it is considered that when the adhesion layer is formed of a metal such as silicon, high adhesion between the undercoat layer, the hard coat layer and the conductive layer forming member can be obtained.

* Others The present invention is not limited to the embodiments described above, and the following modifications are possible.

(1) In the above structure, the undercoat layer is formed in a plurality of layers, but this is one layer (silicon oxide or the like).
Of course, it doesn't matter.

(2) In the above panel structure, the conductive layer forming member 23 is made of resin, but not limited to this, it is made of an inorganic material such as glass, and ITO or the like is directly applied to the member. It is also possible to form a conductive layer and to attach it to a support member on which an adhesive layer is formed in advance.
In this case, the conductive layer forming member 23 made of glass also serves as the undercoat layer.

[Example] Based on the above-mentioned embodiment, a transparent conductive film comprising a conductive layer forming member, a conductive layer, an undercoat layer and an adhesion layer as shown in Table 1 below was produced.

[0039]

[Table 1] Films are transparent conductive films according to the examples, and films are comparative examples.

That is, in the film, polyethylene terephthalate (PET) was used for the conductive layer forming member, the adhesion layer was a silicon film having a thickness of 10Å, the undercoat layer was a silicon oxide film having a thickness of 500, and the conductive layer was a thickness of 300Å. ITO
It is composed of each film.

Like the film, polyethylene terephthalate (PET) is used for the conductive layer forming member of the film, the adhesion layer is made of a silicon film having a thickness of 10 Å, and the conductive layer is made of an ITO film having a thickness of 300 Å. The undercoat layer is composed of two layers, a zinc oxide-tin oxide based film having a thickness of 600Å is arranged on the side closer to the conductive layer forming member, and a silicon oxide film having a thickness of 450Å is arranged as an upper layer. .

The film has the same structure as the film except that the adhesion layer is made of an alloy of zinc and tin.

The film has the same structure as the film, except that the adhesion layer is composed of an alloy of silicon and tin.

The film is a film in which the adhesion layer is not arranged in the film structure.

The film is a film in which the adhesion layer is not provided in the constitutions of film to.

The visible light transmittances of the wavelengths of 550 nm of the respective films are, as described in the rightmost column of Table 1, 90.5% for the film, 90.7% for the film, and 95.1 for the film. %, The film is set to 95.2%, the film is set to 94.8%, and the film is set to 95.0%. Above all, in the case of film, by forming the undercoat layer into two layers, it is more than in the case of one layer. The light transmittance is set higher to improve the transparency of the film.

The following experiments were carried out using the films having the above-mentioned structures to examine their characteristics.

Experiment 1 (alkali resistance experiment): Each film prepared in a 2% aqueous solution of NaCl (under 25 ° C.) was subjected to a predetermined time (5
(15 minutes, 15 minutes, 5 hours, 15 hours), after immersion, and after washing with water, the tape peeling test was performed, and the ITO electrode surface was observed under a microscope and the resistance value of the ITO electrode surface was also measured.

In the tape peeling test, an adhesive tape is attached to the ITO electrode side of the transparent conductive film, and this is peeled off only once.

Experiment 2 (high temperature and high humidity resistance experiment): In this experiment, each of the produced films was left in a high temperature and high humidity environment of 80 ° C. and 90% humidity for a predetermined time (24 hours, 120 hours, 500 hours). After that, the ITO electrode surface of the tape peeling test was observed under a microscope, and the resistance value of the ITO electrode surface was also measured.

By the experiments 1 and 2, the adhesion between the PET film, which is a conductive layer forming member, and the adhesion layer is evaluated.

Results of Experiments; Results of Experiments 1 and 2 are shown in Table 2 below.

[0053]

[Table 2] In addition, in this table, in the column of the result of the microscope observation, ○, △, ×
These symbols represent the difference in the degree of change in the surface state of the conductive layer. ○ indicates no change, and △ indicates that the conductive layer is not peeled but cracks occur on the surface. The symbol x indicates that the conductive layer is peeled off. In addition, the resistance value is the initial value (320Ω /
Unit area, film: 300Ω / unit area, film: 302Ω / unit area, film: 310Ω / unit area, film: 305Ω / unit area, film: 298Ω / unit area. ).

As is apparent from the results shown in this table,
A film according to a comparative example, which is not provided with an adhesion layer,
Did not give very good results in the alkali tolerance experiment. That is, with these films, as a result of microscopic observation, the film was immersed in an alkaline aqueous solution for 5 minutes.
A crack was generated on the surface of the conductive layer, and if it was immersed in an alkaline aqueous solution for 5 hours, the conductive layer was clearly peeled off. In addition, the surface resistance of the conductive layer increased as the immersion time became longer, and both of them increased to such an extent that they could not be measured after 15 hours of immersion. It was

[0055] On the other hand, the fill-time according to the first embodiment,
In and, good results were obtained. That is, 15
Even when immersed in an alkaline aqueous solution for a period of time, peeling was not observed to the extent that cracks were found in the film and the resistance value was only 1.13 times the initial value even after 15 hours. It wasn't.

Next, looking at the results of the high temperature and high humidity resistance experiment, the film according to the comparative example did not give very good results. That is, in these films
As a result of microscopic observation at 20 hours, a crack was generated on the surface of the conductive layer, and an increase in the resistance value was observed as the time of keeping in the high temperature and high humidity environment was increased. At 500 hours, the initial resistance value was 4%. It was almost double.

[0057] On the other hand, the fill-time according to the first embodiment,
In and, good results were obtained. That is, 50
Even when the film was placed in a high temperature and high humidity environment for 0 hours, no deformation was observed in all the films, and the resistance value was 500 times maximum, which was 1.15 times the initial value.

The results of these experiments are shown in
And , and, as compared with the film according to the comparative example, and shows that the adhesion of the conductive layer is very high, therefore,
This shows the effectiveness of the adhesion layer made of metal.

The rate of increase of the resistance value of the film was smaller than that of the film of the comparative example in both the alkali resistance test and the high temperature and high humidity resistance test. This indicates that one layer of the undercoat layer provided on the film slightly contributes to the improvement of the adhesion to the PET film.

As described above, the transparent conductive material of the present invention
The conductive film, a conductive layer forming film, a conductive layer, a layer composed of a metal oxide formed between the conductive layer forming film and the conductive layer and two layers having different optical characteristics
Therefore, compared with before setting the light transmittance of the entire transparent conductive film.
Undercoat layer to increase overall
And a single metal element contained in the metal oxide formed between the undercoat layer and the conductive layer forming film or at least 1 contained in the metal oxide.
And a metal layer made of an alloy of two or more kinds of metal elements including seeds.

This makes it possible to improve the adhesion between the undercoat layer and the transparent conductive film and prevent the conductive layer from falling off.

[Brief description of drawings]

FIG. 1 is an exploded view of a touch panel to which a transparent conductive film according to an embodiment is applied.

FIG. 2 is a cross-sectional view of the touch panel.

[Explanation of symbols]

1 touch panel 10 Touch side substrate 11 Hard coat layer 12 Conductive layer forming member 13 Undercoat layer 14 Conductive layer 15 Adhesion layer 20 Display side board 21 Hard coat layer 22 Support member 23 Conductive layer forming member 24 Undercoat layer 25 Conductive layer 26 Adhesion layer 27 Adhesive layer 30 spacers 31 Air layer 40 adhesive 141,142 electrodes 143, 144 Connector electrode 145,146 Wiring pattern 251,252 electrodes 253,254 Connector electrode 255,256 wiring pattern

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kotaro Tanimura, 163 Morikawahara-cho, Moriyama-shi, Shiga Gunze Co., Ltd. Research and Development Department (56) Reference JP 9-24574 (JP, A) JP 4-28114 (JP, A) JP 8-267645 (JP, A) JP 10-323932 (JP, A) JP 11-20076 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) B32B 1/00-35/00 H01B 5/14 EUROPAT (QUESTEL) WPI / L (QUESTEL)

Claims (3)

(57) [Claims] 1. A layer composed of a conductive layer forming film, a conductive layer, and a metal oxide formed between the conductive layer forming film and the conductive layer, and two layers having different optical characteristics.
Therefore, compared with before setting the light transmittance of the entire transparent conductive film.
Undercoat layer to increase overall
And a single metal element contained in the metal oxide formed between the undercoat layer and the conductive layer forming film or at least 1 contained in the metal oxide.
A transparent conductive film, comprising a metal layer made of an alloy of two or more metal elements including a seed. 2. The undercoat layer is composed of two layers having different photorefractive indexes, and the layer having the low photorefractive index is closer to the conductive layer than the layer having the high photorefractive index. The transparent conductive film according to claim 1. 3. The transparent conductive film according to claim 1, wherein the metal layer is made of a metal selected from the group consisting of silicon, titanium, tin and zinc.