JP3310409B2 - 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. However, a thin film exhibiting a transparent conductive function usually has a thickness of only 0.1 μm or less, and is susceptible to mechanical rubbing and hitting. By bonding a protective film during transportation and storage, it is possible to prevent this thin film from being damaged.However, processing into elements and devices may involve a step of heating to a high temperature. Since there is no high heat resistance, the transparent conductive thin film is cut into cut sheets and fixed to a glass plate or the like so that the surface of the transparent conductive thin film is not rubbed or hit. In addition, an undercoat layer is applied between the transparent conductive thin film and the base film so as not to be damaged even if rubbed or hit, and the type, composition, and crystal structure of the transparent conductive thin film are improved. ing. However, processing with single wafers loses the greatest advantage of allowing the film to be processed in a roll process as a continuous body, and there is no problem with contacting the transfer roll in the roll process. The development of is eager. on the other hand,
Examination of undercoats and thin films has not yet yielded satisfactory results. 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. This makes it possible to form a barrier layer on the back surface of the film on which the transparent conductive thin film is laminated by a heating process, or to laminate a heat-resistant polarizing plate or a retardation film in a heating step. However, when the film is continuously processed by the roll process, there is a problem that the transparent conductive thin film is damaged.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a heat-resistant film which can be processed continuously by a roll process which is free from damage due to heat even if a heating step of 120 ° C. or more is added in the processing process and does not damage the transparent conductive thin film. It is to provide a transparent conductive film.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by providing a thin film of a heat-resistant transparent conductive film in which a thin film 1 having transparent conductivity is laminated on a plastic film 2 having a glass transition temperature of 120 ° C. or higher. A protective film comprising a plastic film 3 having a glass transition temperature of 120 ° C. or higher and an adhesive layer 4 having a thermal decomposition temperature of 120 ° C. or higher and an adhesive force of 50 g / cm or lower provided on a base through the adhesive layer. It was solved by bonding together.

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
The adhesive used in the above is selected from an acrylic adhesive, a silicone adhesive, an EVA resin adhesive, and the like. To provide the adhesive on the surface of the plastic film, coating or extrusion lamination is used. The adhesion between the plastic film surface and the adhesive must be sufficiently greater than the adhesion between the transparent conductive thin film 1 and the adhesive layer 4.
For that purpose, it is effective to perform corona treatment or primer coating on the surface of the plastic film.
The adhesive strength between the transparent conductive thin film 1 and the adhesive layer 4 is 50 g / cm.
Above, the peeling becomes difficult, a special design is required for the automatic peeling mechanism in the roll process, and the productivity is hindered. Further, the transparent conductive thin film may be damaged at the time of peeling, which is not preferable. As for the thickness of the plastic film, the thinner is advantageous in terms of cost, but the thicker is more advantageous in the reinforcing effect of the transparent conductive film in the state of being bonded. It is preferable that the thickness of the pressure-sensitive adhesive layer 4 be small, since the heat resistance of the plastic film as the base material is not easily damaged. The glass transition temperature of the adhesive is 120 ° C.
Even if the temperature is below, the 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.)
An acrylic pressure-sensitive adhesive was coated to a thickness of 5 μm on a glass transition temperature of 216 ° C. and a thickness of 25 μm) to prepare 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., thickness: 100 μm), and ITO was sputtered on its surface. With thickness 0.0
The transparent conductive film formed to 3 μm was bonded to the ITO surface. The roll of this laminated film is unwound, and the surface on which the heat-resistant protective film is not stuck is coated with a barrier varnish containing polyvinyl alcohol as a main component by a reverse coater, and is continuously dried in a dryer at 150 ° C. for 10 minutes. After being transported and dried, it was wound again. The heat-resistant protective film was not peeled or deformed in the dryer. Although there were 50 support rolls in contact with the heat-resistant protective film side of this coating and drying machine, the heat-resistant protective film of the wound laminated film was peeled off, and the ITO surface was magnified 100 times with a polarizing microscope equipped with a differential interference device. No scratch was observed on the ITO surface.

(Example 2) Polycarbonate resin (GE
Pexan 141, glass transition point 145 ° C.) is formed into a 300 μm film by an extrusion film forming method, and EVA resin (Evaflex manufactured by DuPont Mitsui) is extruded and laminated on one surface of the film. A protective film was prepared and wound into a roll. This heat-resistant protective film was extruded into a roll-shaped polycarbonate film (glass transition temperature: 145 ° C., thickness: 300 μm).
m) was undercoated, and ITO was bonded to the ITO surface of the transparent conductive film formed on the surface thereof to a thickness of 0.1 μm by a sputtering method. A phase difference plate (thickness: 1) formed by applying an epoxy resin-based adhesive to the surface of the laminated film roll to which the heat-resistant protective film is not adhered while unwinding and uniaxially stretching the polycarbonate film.
00 μm), and bonded by a belt-type continuous heating press at 120 ° C. under a heating condition of ² kg / cm ² for 5 minutes,
I rolled it up again. After the pressing, the heat-resistant protective film was not peeled off or deformed. The belt surface was in full contact with the surface on the heat-resistant protective film side,
Peeling off the heat-resistant protective film of the wound laminated film, I
Even when the TO surface was observed at 100 times with a polarizing microscope equipped with a differential interference device, no scratch was observed on the ITO surface.

Comparative Example 1 The barrier coating of Example 1 was performed without attaching a heat-resistant protective film to the ITO surface. When the ITO surface after coating was observed at 100 times with a polarizing microscope equipped with a differential interference device, a myriad of scratches considered to have occurred due to contact with the support roll of the coating / drying machine were observed on the ITO surface. (Comparative Example 2) A protective film (sanitect E manufactured by San-A Kagaku Kogyo Co., Ltd.) having a polyester film having a glass transition temperature of 80 ° C as a base and coated with an acrylic adhesive was heat-resistant. When the polyester film was used in place of the protective film, the polyester film shrunk inside the dryer and uneven coating of the coating film occurred. (Comparative Example 3) The barrier coating of Example 1 was heat-resistant using a polyethylene film having a glass transition temperature of -125 ° C as a base, and a protective film (SANITECT PAC manufactured by San-A Chemical Industry Co., Ltd.) on which an EVA resin was coextruded and laminated. When the film was used in place of the protective film, the polyethylene film shrank after leaving the dryer, and the entire laminated film was greatly curled and bent and damaged by the support roll.

[0010]

According to the present invention, it is possible to perform a process requiring a heating step on a back surface of a transparent conductive thin film having high heat resistance on which a transparent conductive thin film is formed by a continuous process in a roll shape. Become.

[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 plastic film substrate having a glass transition temperature of 120 ° C. or higher, and a plastic decomposition substrate having a glass transition temperature of 120 ° C. or higher is formed on the thin film. Is 120 ° C
A transparent conductive film, characterized in that a protective film provided with an adhesive layer having an adhesive strength of 50 g / cm or less and being adhered to each other via an adhesive layer.