JPH02276106A - Transparent conductive film - Google Patents

Abstract

PURPOSE:To offer a transparent conductive film with high adhesion of a base film to a conductive layer and excellent durability by providing the underlying layer of coat forming agent including thermoplastic polyester group resin between the base film and the conductive layer. CONSTITUTION:A specially recommended example of a synthetic resin film as a base film is polyethylene terephthalate film. For a conductive layer which is formed on the base film via an underlying layer, metal and/or metal oxide such as gold, silver, copper, palladium, indium oxide, tin oxide, zinc oxide, or etc., preferably indium oxide, tin oxide or these mixed oxide are adapted. For the main element of coat forming agent including polyester group resin for the underlying layer formed to improve adhesion of the conductive layer, polyethylene terephthalate that ethylene glycol is transformed in part by polyglycol is suitable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transparent conductive film in which a conductive layer is formed on a base film, and more specifically, a transparent conductive film with improved adhesion of the conductive layer to the base film. Regarding conductive films.

[Prior Art] Conventionally, display elements such as liquid crystal cells, electroluminescence, and electrochromic touch panels generally include:
Transparent conductive materials such as Nesa Glass, which are made by forming a conductive layer on glass, have been used, but in recent years, transparent conductive films that use a synthetic resin film as a base material and have a conductive layer formed thereon have been used. The use of is increasing. Those using synthetic resin film as the base material are flexible,
In addition to being easy to work with, it is lightweight and does not break like glass. The synthetic resin film used for the base material may be selected from various types depending on the purpose, but polyethylene terephthalate is usually used from the viewpoint of transparency and strength.

[Problems to be Solved by the Invention] However, in transparent conductive films based on synthetic resin films, the adhesion between the base film and the conductive layer is insufficient, making it difficult to apply them to display element products such as the aforementioned liquid crystal cells. In this case, the conductive layer may peel off during use of the product, or cracks may occur in the conductive layer due to operations such as pen input, resulting in low durability of the product.

An object of the present invention is to solve the above-mentioned conventional problems and provide a transparent conductive film with high adhesiveness between a base film and a conductive layer and excellent durability.

[Means for Solving the Problem] The transparent conductive film of claim (1) is a transparent conductive film in which a conductive layer is formed on a base film made of a synthetic resin film, in which the base film and the conductive layer are bonded together. Between,
The transparent conductive film of claim (2), characterized in that a base layer of a coating film forming agent containing a thermoplastic polyester resin is provided, is the transparent conductive film of claim (1), wherein the thermoplastic polyester resin is polyethylene terephthalate. It is characterized by being a modified ether type polyester resin in which 5 to 50 mol% of the ethylene glycol component of is substituted with polyethylene glycol.

The present invention will be explained in detail below.

The present inventors have conducted intensive studies to improve the adhesion between the base film and the conductive layer and to provide a transparent conductive film with excellent durability.
By providing a base layer of a coating film forming agent containing a thermoplastic polyester resin (hereinafter simply referred to as the "base layer"), the adhesion between the conductive layer and the base film is improved, and the durability of the product is increased. They have found that this is a significant improvement and have completed the present invention.

In the present invention, preferred examples of the synthetic resin film for the base film include commonly known transparent plastic films such as polyethylene terephthalate, polysulfone, polycarbonate, polyethersulfone, and polybutylene terephthalate, among which polyethylene terephthalate film is preferred. Particularly preferred. The thickness of this film is usually preferably 30 to 200 μm.

The conductive layer formed on the base film via the base layer is made of metal and/or metal oxide, such as gold, silver, copper, palladium, indium oxide, tin oxide, zinc oxide, etc., preferably indium oxide (In20s). ), tin oxide (S
n02) or a mixed oxide thereof (hereinafter referred to as rITOJ).

Suitable examples of the coating film forming agent containing the thermoplastic polyester resin for the base layer formed to improve the adhesion of the conductive layer include those that are usually commercially available as coating agents or adhesives. The main component of the coating film forming agent containing these polyester resins is preferably one in which a part of the ethylene glycol component of polyethylene terephthalate is modified with polyglycol or the like. Specifically, a modified ether type polyester resin represented by the following structural formula, in which 5 to 50 mol % of the ethylene glycol component of polyethylene terephthalate is replaced with polyethylene glycol, can be mentioned.

An appropriate amount of epoxy resin, polyvinylidene chloride resin, etc. may be blended with such thermoplastic polyester resin for the purpose of improving the heat resistance, moisture resistance, chemical resistance, flexibility, etc. of the base layer.

In this case, as the epoxy resin, for example, common (epoxy) resins such as bisphenol A type and alicyclic type, or mixtures thereof are suitably used. The amount of epoxy resin blended is 10 to 901% by weight based on the thermoplastic polyester resin.
In particular, the content is preferably 30 to 70% by weight. If the amount of epoxy resin is too large, the adhesiveness of the thermoplastic polyester resin to the base material and the i! i
! - Reasonability is impaired, and the original flexibility of thermoplastic polyester resin is impaired, and I! This makes it easier for cracks to occur in the conductive layer.

Vinylidene chloride-based resins are usually copolymerized with vinylidene chloride as the main ingredient, and copolymerized with copolymerizable components such as acrylonitrile, vinyl chloride, acrylic esters, and methacrylic esters. suitable. The proportion of the vinylidene chloride component in this copolymer is usually preferably 60 to 99 mol%, especially 70 to 95 mol%.The blending amount of the vinylidene chloride resin is 0.0% to the thermoplastic polyester resin.
It is preferably 1 to 20% by weight, particularly 0.1 to 10% by weight. If the blending amount of the vinylidene chloride resin is too large, the inherent adhesion of the thermoplastic polyester resin to the base material and the adhesion to the conductive layer will be impaired.

Next, a method for manufacturing the transparent conductive film of the present invention will be explained.

To manufacture the transparent conductive film of the present invention, first, a base layer is formed on a base film. As a method for forming the base layer, for example, a thermoplastic polyester resin and, if necessary, an appropriate amount of epoxy resin, vinylidene chloride resin, etc., are dissolved in an organic solvent, and the resulting resin stock solution is applied to the surface of the base film. A method of coating and then heat treatment can be adopted. The organic solvent used here is not particularly limited as long as it dissolves the resin, but if the boiling point is too low or too high, unevenness may occur during coating.
Since defects such as sagging and repelling are likely to occur, these points should be taken into consideration when selecting an appropriate material. Specifically, methyl ethyl ketone, toluene, ethylene glycol monomethyl ether,
Ethylene glycol monoethyl ether, ethyl acetate,
Preferably, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 4-methoxy-4-methylpentanone-2, and mixtures thereof are used. The amount of such organic solvent used is usually such that the resin concentration is 1 to It is appropriately determined to be 5% by weight.

For example, a bar coater can be used to apply the resin stock solution.
Various coating methods can be employed, such as coating using a doctor blade or the like, or coating using a spin coater, gravure coater, forward rotation coater, reverse coater, etc.

As the heat treatment method, a method of heating the entire base film coated with the resin stock solution at a temperature of 120 to 200°C is usually suitable. This heat treatment dries and hardens the coating liquid, forming a resin base layer.

In the present invention, the thickness of the base layer formed in this way is usually preferably about 0.01 to 1 μm.

Next, a conductive layer made of the metal and/or metal oxide is formed on this base layer. The conductive layer is preferably formed using a sputtering method. In the sputtering method, a target is usually installed on the cathode electrode, and
It is carried out by applying a voltage of about 100 to 500 V in an atmosphere of an inert gas such as argon whose pressure is reduced to about 10 -2 Torr. At this time, the ionized argon atoms are accelerated toward the target and collide with each other, so that atoms, molecules, etc. constituting the target are knocked out and stacked on the base layer.

In the present invention, the target material used is particularly one in which the ratio of indium oxide to tin oxide is 9°:10 to 90:5.
(% by weight) lTo is preferred.

In addition, when using argon gas, the pressure in the reaction system is as follows:
Normally, it is about 10''a to 10-'T or r, but at the same time oxygen gas is
It is preferable to introduce at a pressure of about r.

In the present invention, the thickness of the conductive layer is preferably in the range of 50 to 2000 A, but since this thickness is correlated with the resistance value of the conductive layer, it is appropriately selected depending on the purpose.

In addition, in this invention, such a base layer and a conductive layer may be formed on one side of a base film, or may be formed on both sides.

[Function] The base layer of the coating film forming material containing the thermoplastic polyester resin has very high adhesion to both the base film and the conductive layer. Moreover, the base layer according to the present invention does not impair the transparency of the film.

Therefore, by forming such a base layer, the adhesion of the conductive layer is improved, and a transparent conductive film with excellent durability can be obtained.

In particular, by employing the thermoplastic polyester resin according to claim (2), a remarkable effect of improving adhesion can be obtained.

[Examples] The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Biaxially stretched polyethylene terephthalate film (thickness 1
A commercially available thermoplastic polyester resin adhesive ("Stafix" manufactured by Fuji Photo Film ■) was applied to one side of the 75 μm)
(Resin concentration 30% by weight) 10g was mixed with a mixed solvent of methyl ethyl ketone and 2-methoxyethyl acetate (1:1 weight ratio)9
After applying the resin stock solution dissolved at 0g with a bar coater,
The resin was cured by heat treatment at 140° C. for 3 minutes in a hot air dryer to form a base layer with a thickness of 0.1 μm. On this base layer, a DC magnetron sputtering device was used to apply a pressure of 3X10-'Torr and a voltage of about 320
Indium oxide (95 Ii mass%) and tin oxide (5
A transparent conductive film was produced by forming an ITO conductive layer with a thickness of about 250 Å consisting of 1% by weight).

The properties of this film are shown in Table 1.

Furthermore, the durability of this film was evaluated by measuring the uniformity (linearity) of the surface electrical resistance before and after the dot test using the method described below. The results are shown in Table 1.

Sample 1 is 10100mm x 10mm as shown in Figure 1.
0, and electrodes IA and IB with a width of 5 mm were prepared by applying silver paste to both ends of the side surface on which the conductive layer was formed. A DC voltage (5 V) 2 is applied between the electrodes IA and IB, and a total of 49 potentials are applied at intervals of 2 mm in the vertical and horizontal directions in a range 3 of 6 mm in length and 30 mm in width at the center of the sample (the range surrounded by the broken line in Figure 1).
Measurements were made at 6 points. Then, the computer outputs the deviation between the theoretical voltage at each point and the actual measured value when the surface electrical resistance of the sample is assumed to be completely uniform (see Figure 3), and this is calculated as the gluability before the dot test. did.

Next, as shown in FIG. 2, the sample 1 was placed on the conductive surface 1a with a distance d of 50 μm from the Nesa glass 4.

Comrades 4a were fixed facing each other. In this state, 40 points were scored in a straight line at the center of the sample 1 at an inch pitch using a polyacetal ben 5 (tip diameter: 0.8).

The scoring was done by hitting each point P 10 times with a force of 10 mJ. After this, the deviation between the theoretical voltage at each point and the actual measured value was outputted to the computer in the same manner as above (see FIG. 4). This was defined as the degree of friction after the RBI test.

In the gauging nearness before the dot test shown in FIG. 1, the distance of the part where the distance between adjacent lines is the largest is Wo, and the distance after the dot test is WI, WI/w.

Durability was evaluated.

Example 2 As a resin stock solution, 10 g of the thermoplastic polyester resin adhesive used in Example 1, epoxy resin (rKTX-911-2J manufactured by Asahi Denka Kogyo ■, resin concentration 100% by weight) 0
．． 6g, and epoxy curing agent (rCP manufactured by Asahi Denka Kogyo ■)
A transparent conductive film was produced in the same manner as in Example 1, except that a resin stock solution was used in which 0.018 g of -77J, resin concentration 100% by weight was dissolved in 100 g of the mixed solvent used in Example 1.

Table 1 shows the properties and durability test results of the obtained film.

Example 3 As a resin stock solution, 10 g of the thermoplastic polyester resin adhesive used in Example 1 and 0.3 g of vinylidene chloride resin (Saran Resin R202J, solid content 100% by weight, manufactured by Asahi Denka Kogyo ■) were added to Example 1. A transparent conductive film was produced in the same manner as in Example 1, except that a resin stock solution dissolved in 100 g of the mixed solvent used in Example 1 was used.

Table 1 shows the properties and durability test results of the obtained film.

Comparative Example 1 A transparent conductive film was produced in the same manner as in Example 1, except that no base layer was formed.

When the obtained film was subjected to a durability test in the same manner as in Example 1, the surface electrical resistance ratio (W+/Wo) before and after the dot test was 15, and the durability was poor.

Comparative Example 2 Epoxy resin (rCP- manufactured by Asahi Denka Kogyo ■) as resin stock solution
77J, resin concentration 100% by weight) 0.3g toluene 9
A transparent conductive film was produced in the same manner as in Example 1, except that the base layer was formed using a resin stock solution dissolved in 0 g.

When the obtained film was subjected to a durability test in the same manner as in Example 1, the surface electrical resistance ratio (W+/Wo) before and after the dot test was 19, and the durability was poor.

From Table 1, it is clear that according to the present invention, the adhesion of the conductive layer is improved without impairing transparency and conductivity, and a transparent conductive film with extremely excellent durability is provided. be.

[Effects of the Invention] As detailed above, the transparent conductive film of the present invention has excellent transparency and conductivity, and also has extremely high adhesion between the conductive layer and the base film. A highly durable, high-performance transparent conductive film with almost no problems such as peeling or breakage is provided.

In addition, when the thermoplastic polyester resin of claim (2) is employed, the above-mentioned adhesiveness becomes even more excellent.

Therefore, by using the transparent conductive film of the present invention, the lifespan of various display element products etc. can be significantly extended.

[Brief explanation of drawings]

FIG. 1 is a plan view illustrating the durability test method, FIG. 2 is a sectional view of the same, and FIGS. 3 and 4 are computer analysis diagrams of the voltage before and after the test, respectively. 1...Sample, 4...Nesa Glass, 5...Pen. Figure 1

Claims (2)

[Claims] (1) In a transparent conductive film in which a conductive layer is formed on a base film made of a synthetic resin film, a base layer of a coating film forming agent containing a thermoplastic polyester resin is placed between the base film and the conductive layer. A transparent conductive film characterized by: (2) The transparent conductive film according to claim 1, wherein the thermoplastic polyester resin is a modified ether type polyester resin obtained by replacing 5 to 50 mol% of the ethylene glycol component of polyethylene terephthalate with polyethylene glycol. .