JP3310408B2 - Transparent conductive film - Google Patents

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 used for a film liquid crystal display device, an organic dispersion type electroluminescence device, a transparent touch panel input device and the like.

[0002]

2. Description of the Related Art Conventionally, a transparent conductive film in which an indium and tin oxide thin film is laminated on a surface of a polyester film or the like by a method such as sputtering has been used for a film liquid crystal display device, an organic dispersion type electroluminescence device, or the like. It is used as a material for a transparent electrode substrate of a transparent touch panel input device. In the process of processing a transparent conductive film into these elements and devices, the greatest advantage of being a film material is that it can be processed continuously by a roll process. Thin films that exhibit a transparent conductive function usually have a thickness of only 0.1 μm or less and are vulnerable to mechanical rubbing and hitting, so careful handling is required. The surface opposite to the surface on which the surface is formed must be protected from scratches because appearance is an important application. Normally, it is possible to prevent the transparent conductive film from being damaged by attaching a protective film to the opposite surface, but it may include a step of heating to a high temperature when processing into an element or device. Since there is no protective film having a high heat resistance, a device such as an air support or a tenter support in a sprocket hole has been considered so as not to come into contact with the support roll surface in the roll process. However, these methods require high capital investment and detract from the advantages of the roll process. Therefore, development of a transparent conductive film having no problem even if it comes into contact with a supporting roll in a roll process is eagerly desired. Conventionally, a transparent conductive film which is not damaged by heat even when a heating step of 120 ° C. or more is added in a processing process has been developed. Thereby, in the film liquid crystal display device, the firing of the alignment film and the sealing resin can be performed at 120 ° C. or higher, and the display quality and durability can be improved. Further, in the case of a dispersion-type electroluminescent element or a transparent touch panel device, printing and baking of silver paste or the like can be performed at 120 ° C. or higher, and an element or device having high adhesion and excellent reliability can be produced. However, when the film is continuously processed by the roll process, there is a problem that the surface opposite to the surface on which the transparent conductive thin film is formed is damaged.

[0003]

According to the present invention, there is no damage due to heat even if a heating step of 120 ° C. or more is applied in the processing process, and there is no damage to the surface opposite to the surface on which the transparent conductive thin film is formed. An object of the present invention is to provide a heat-resistant transparent conductive film that can be continuously processed by a roll process.

[0004]

In order to solve the above-mentioned problems, the present invention provides a heat-resistant transparent conductive film in which a transparent conductive thin film 1 is laminated on a first plastic film 2 having a glass transition temperature of 120 ° C. or higher. On the surface opposite to the surface on which the thin film of the conductive film is formed, the first glass having a glass transition temperature of 120 ° C. or higher
20pp difference in linear expansion coefficient from plastic film
m / ° C. or less, a second plastic film 3 substrate having a thermal decomposition temperature of 120 ° C. or more and an adhesive strength of 50 g
This is solved by bonding a protective film provided with an adhesive layer 4 having a thickness of not more than / cm through the adhesive layer 4.

Examples of the plastic films 2 and 3 having a glass transition temperature of 120 ° C. or higher include films made of resins such as polycarbonate, polyarylate, polysulfone, polyethersulfone, polyetherimide, and polyetheretherketone. Thermal decomposition temperature is 120
Pressure-sensitive adhesive layer 4 having an adhesive strength of 50 g / cm or less
Is selected from acrylic adhesives, silicone-based adhesives, EVA resin-based adhesives, and the like. To provide the adhesive on the surface of the second plastic film 3,
Coating and extrusion lamination techniques are used. The adhesion between the surface of the second plastic film 3 and the adhesive layer 4 must be sufficiently larger than the adhesion between the first plastic film and the adhesive. For that purpose, it is effective to perform corona treatment or primer coating on the surface of the second plastic film. It is also effective to make the surface of the first plastic film poor in adhesion. When the adhesive force between the first plastic film and the adhesive material is 50 g / cm or more, it becomes difficult to peel off, and a special design is required for an automatic peeling mechanism in a roll process, which hinders productivity and also causes transparency when peeling. It is not preferable because the conductive film may be damaged. Second
As for the thickness of the plastic film, a thinner film is more advantageous in terms of cost, but a thicker one is more advantageous in the reinforcing effect of the transparent conductive film in a bonded state. It is preferable that the thickness of the adhesive layer 4 is thin because the heat resistance of the second plastic film is not easily damaged. Even if the glass transition temperature of the pressure-sensitive adhesive is 120 ° C. or lower, the pressure-sensitive adhesive function is not impaired even at a high temperature.

As the transparent conductive thin film 1 in the present invention, an oxide of indium containing 5 to 10% by weight of tin (I
TO) is most suitable, but oxides such as gold, silver, palladium, nickel, cadmium, antimony, and zinc can also be selected. As a method of laminating these thin films on a plastic film, a vacuum evaporation method, a sputtering method,
The ion plating method is selected. Before forming the transparent conductive thin film, it is also effective to apply an undercoating to the surface of the plastic film in order to improve the adhesion.

[0007]

【Example】

(Example 1) Roll-shaped polyetherimide film (Sumilite FS-1450 manufactured by Sumitomo Bakelite Co., Ltd.)
Glass transition temperature 216 ° C, linear expansion coefficient 62ppm / ° C,
(Thickness: 25 μm) was coated with an acrylic pressure-sensitive adhesive to a thickness of 5 μm to form a heat-resistant protective film. This heat-resistant protective film was undercoated with a roll-shaped polyethersulfone film (Sumilite FS-5300, manufactured by Sumitomo Bakelite Co., Ltd., glass transition temperature: 223 ° C., linear expansion coefficient: 54 ppm / ° C., thickness: 100 μm). ITO is deposited on the surface to a thickness of 0.
The transparent conductive film formed to have a thickness of 03 μm was bonded to the polyethersulfone film surface. The roll of the laminated film was heated at 150 ° C. for 10 minutes through a heating furnace designed so that only the surface on which the heat-resistant protective film was stuck was in contact with the support roll or the like while unwinding, and was wound again. The heat-resistant protective film was not peeled off or deformed in the heating furnace and until it was wound after passing.

(Example 2) Polycarbonate resin (GE
Pexan 141, glass transition point 145 ° C., linear expansion coefficient 67 ppm / ° C.) are formed into a 300 μm film by an extrusion film forming method, and EVA resin (Evaflex manufactured by DuPont Mitsui) is formed on one surface of the film. Was extruded and laminated to form a heat-resistant protective film, which was wound into a roll. A roll-shaped polycarbonate film (glass transition temperature: 145 ° C., coefficient of linear expansion: 67 ppm / ° C., thickness: 300) also extruded from this heat-resistant protective film.
μm), and an ITO was adhered to the surface of the polycarbonate film of the transparent conductive film formed to a thickness of 0.1 μm on the surface by sputtering. The roll of the laminated film was heated at 150 ° C. for 10 minutes through a heating furnace designed so that only the surface on which the heat-resistant protective film was stuck was in contact with the support roll or the like while unwinding, and was wound again. The heat-resistant protective film was not peeled off or deformed in the heating furnace and until it was wound after passing.

Comparative Example 1 The heating of Example 1 was performed without attaching a heat-resistant protective film to the polyethersulfone film surface. Numerous scratches generated by rubbing with a support roll or the like were observed on the wound film. (Comparative Example 2) The heating of Example 1 was repeated except that the glass transition temperature was 80%.
When a protective film (sanitect E manufactured by San-A Chemical Industry Co., Ltd.) having a polyester film having a linear expansion coefficient of 12 ppm / ° C. at the base and coated with an acrylic adhesive was used instead of the heat-resistant protective film. The polyester film contracted inside the dryer, the transparent conductive film was deformed, and the ITO surface was damaged. (Comparative Example 3) The heating of Example 1 was repeated except that the glass transition temperature was -1.
Using a polyethylene film having a linear expansion coefficient of 100 ppm / ° C. at 25 ° C. as a base, and using a protective film (SANITECT PAC manufactured by San-A Kagaku Kogyo Co., Ltd.) in which an EVA resin is coextruded and laminated instead of the heat-resistant protective film. However, after leaving the dryer, the polyethylene film shrank, and the entire laminated film was greatly curled and bent and damaged by the support roll.

[0010]

According to the present invention, a process requiring a heating step can be performed on a transparent conductive thin film of a transparent conductive film having high heat resistance by a continuous process in a roll shape.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of one embodiment of the present invention.

Claims (1)

(57) [Claims] 1. A thin film having a transparent conductivity is laminated on a first plastic film substrate having a glass transition temperature of 120 ° C. or higher, and a glass transition temperature is formed on a surface opposite to a surface on which the thin film is laminated. 120 ° C. or higher, and the difference in linear expansion coefficient from the first plastic film is 20 ppm / ° C.
And a protective film provided with an adhesive layer having a thermal decomposition temperature of 120 ° C. or higher and an adhesive force of 50 g / cm or lower is bonded to the second plastic film substrate, which is within, through the adhesive layer. Characteristic transparent conductive film.