JP2918659B2 - Laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] Transparent conductive films are used as transparent electrodes for liquid crystals and touch panels. The present invention is transparent, conductive,
The present invention relates to a transparent conductive laminated film having excellent durability.

[Conventional technology]

Conventionally known transparent conductive films formed on polymer films are metal thin films such as gold, silver, copper, and palladium Compound semiconductors such as indium oxide, tin oxide, and copper iodide, and gold, silver, and copper There is known a laminated film in which a conductive metal film such as palladium is combined with a transparent conductor film so as to be transparent in a visible light region.

However, transparent conductive films having performances applicable to liquid crystal electrodes and touch panels have not been industrially manufactured at low cost.

That is, since the metal thin film has high reflectivity or absorptivity over a wide wavelength range, when the light transmittance is increased, the film becomes thin, and it is difficult to obtain a film having high conductivity and durability.

The compound semiconductor thin film is, for example, a vacuum deposition method,
It can be formed on a polymer film by a thin film formation method in a vacuum such as a sputtering method. A transparent and highly conductive film is usually obtained at a high temperature of 400 ° C. or higher. However, a polymer film has less heat resistance than a glass substrate, and cannot form a thin film at a high temperature. For this reason, when several thousand angstroms are laminated in order to increase the conductivity, curling of the polymer film and cracking of the thin film occur. In addition, in order to uniformly control the characteristics of the coating film, it is necessary to slow down the film formation speed, which lowers the productivity and significantly increases the manufacturing cost.

A typical configuration of the above-mentioned transparent conductive film includes a laminated film formed on a polymer film by sandwiching a metal film with a high refractive film.

For example, Bi ₂ O ₃ / Au / Bi ₂ O ₃ / polymer film formed by vacuum evaporation, reactive evaporation or reactive sputtering, ZnS
/ Ag / ZnS / laminated film of a polymer film or TiO ₂ / Ag / TiO ₂ / polymer film such sandwich structures have been proposed. In particular, those using gold or silver as the metal layer are materials having excellent transparency in the visible light region due to the optical characteristics of gold and silver themselves, and also having favorable characteristics in terms of conductivity. As particularly good. However, silver is chemically unstable and a formed film has poor durability, and gold is expensive and has a problem in terms of cost.

[Problems to be solved by the invention]

It is an object of the present invention to provide an excellent transparent conductive film including various characteristics peculiar to the film, such as warpage, transparency, conductivity and durability of the laminated film.

[Means for solving the problem]

Metal oxide thin film layer, metal thin film layer on a polymer film having a coating layer of an epoxy acrylate ultraviolet curable resin containing a silane coupling agent on at least one side,
A silver alloy comprising a metal oxide thin film layer sequentially laminated and having a sheet resistance of 50Ω / port or less, a light transmittance of 70% or more, and the metal thin film layer containing 3% to 30% by weight of palladium based on the total weight. A laminated film characterized by being a metal thin film layer.

The present invention has excellent transparency, conductivity, flatness, and durability without the above-mentioned drawbacks in the prior art, and has obtained a laminated film having the following structure as a result of studying a laminate having strong adhesion. I have reached.

 Hereinafter, the present invention will be described in detail.

The polymer film used in the present invention is a transparent film or sheet having flexibility, and for example, a polyester film such as polyethylene terephthalate and a sulfone film such as polysulfone and polyethersulfone can be used.

As the resin of the organic coating layer forming the coating film on the film, the adhesive force is required for both the polymer film metal oxide and is achieved when the silane coupling agent is added to the epoxy acrylate prepolymer. I found something. The amount of silane coupling agent added is 0.
5 to 1% by weight is desirable. Examples of the silane coupling agent include KMB-503, KMB-603 and KMB of Shin-Etsu Chemical Co., Ltd.
-803, A-187 of Nihon Unicar Co., Ltd. is used,
Particularly, those having an epoxy group, an amino group, and a mercapto group are preferable. The epoxy acrylate prepolymer preferably has a melting point of 50 ° C. or higher.

The laminated film of the present invention is obtained by sequentially laminating a metal oxide thin film layer, a metal thin film layer, and a metal oxide thin film layer on the organic coating. It is a silver alloy metal thin film containing 30% by weight of palladium.

When trying to use silver for the metal layer as the conductive layer of the transparent conductive film, silver is poor in durability, and as a result of studying to improve the durability to the extent that it can withstand practical use, silver was replaced with silver palladium alloy Is found to be effective.

The thickness of the metal thin film is not particularly limited as long as it has the required performance as transparent conductivity. However, in order to have conductivity, it is necessary to have continuity in at least a certain region. As a film thickness that shifts from an island structure to a continuous structure
50 mm or more and 500 mm or less are desirable from the viewpoint of transparency. When the ratio of palladium to silver is 3% by weight or more, the target laminate does not whiten even when left in an atmosphere of 80 ° C. and 90% HR for 200 hours. Preferably, when the palladium content is 5% by weight or more, the wet heat resistance is further improved. Durability tends to increase as the palladium content increases, but transparency decreases. For this reason, when the content of palladium is 30% by weight or more, the transparency is significantly reduced. The content of palladium is preferably from 5 to 15% by weight from the viewpoint of harmonizing the durability of the electrical and optical characteristics of the target laminate. What constitutes the metal oxide layer is not particularly limited as long as it has a transparent high refractive index and a low specific resistance, but the refractive index is 1.6 or more, preferably 1.7 or more with respect to visible light. It is effective that the sheet resistance is 300 Ω / port or less and the light transmittance is 80% or more. Those satisfying these conditions include indium, oxides of tin alloys, and tin oxide.

The present invention is used as a laminated film in which a laminate in which a thin layer of silver or a palladium alloy is used as a metal layer and both sides of which are covered with an indium oxide thin film is provided on polyethylene terephthalate coated with an epoxy acrylate prepolymer as a coating resin.

That is, a polymer film such as a polyethylene terephthalate film has a drawback that the adhesiveness with a metal oxide thin film is low, and as a result, the durability of the laminated film is poor. By applying an excellent organic coating, the durability could be improved.

When the laminated film according to the present invention is used for a liquid crystal or the like, it is necessary to prevent the transmission of air from the film side. When air passes through, air bubbles are generated in the liquid crystal, which is fatal in appearance.

Due to optical characteristics, polyethersulfone, which is an amorphous polymer, is suitable for liquid crystal applications. However, amorphous polymer films generally have high air permeability, and it is difficult to prevent liquid crystal from deteriorating. Therefore, in such a case, a polyethersulfone film having an organic coating layer having a gas barrier property, heat resistance, hydrochloric acid resistance, and strong adhesion to polyethersulfone can be used. As the organic coating layer, for example, a layer in which a urethane-based resin layer, a polyvinyl alcohol resin layer, and an epoxy-based thermosetting resin layer are sequentially laminated on polyethersulfone can be used. Unless otherwise specified, the light transmittance indicates a value at a wavelength of 600 nm.

Example 1 A biaxially stretched polyethylene terephthalate film having a light transmittance of 86% and a thickness of 75 μm was used as a polymer film, and an epoxy acrylate prepolymer having a molecular weight of about 1040 and a melting point of 55 ° C. (showa polymer UR-9 manufactured by Corporation
0) 100 parts by weight, 200 parts by weight of diethylene glycol, 100 parts by weight of ethyl acetate, 2 parts by weight of benzene ethyl ether,
1 part by weight of silane coupling agent is dissolved by stirring at 50 ° C, and a uniform solution is applied on both sides by dipping, heated at 80 ° C for 10 minutes and irradiated with ultraviolet rays to form an organic coating layer. An ITO film having a thickness of 300 mm is formed by a reactive sputtering method, and a silver alloy film containing 7.5% by weight of palladium is formed as a third layer by a sputtering method to a thickness of 150 mm.
As the fourth layer, an ITO film having a thickness of 300 mm was formed by a reactive sputtering method in the same manner as the second layer to obtain a laminated film.

The light transmittance of this laminated film is 71%, sheet resistance
It was 20Ω / mouth. In an atmosphere with a temperature of 80 ° C and a humidity of 90% HR
When the laminated film was allowed to stand for 400 hours, the change in sheet resistance was 1.1 times or less, and no change was observed in appearance.

(Comparative example)

Same laminated film except that organic coating was not applied and silver of metal layer and palladium alloy were replaced by silver alone.
When the laminated film was left for 400 hours, the change in the sheet resistance value was 1.5 times or more, and purple spots were generated in the thin film portion on the laminated film.

Examples 2 to 5 Transparent conductive films were produced in the same manner as in Example 1 except that the composition of the metal thin film layer was changed as shown in Table 1. Table 1 shows the changes in palladium (Pd) ratio, light transmittance, sheet resistance, and appearance after the wet heat test at 80 ° C./90%/200 hours.

[Effects of the Invention] The transparent conductive laminated film of the present invention has good adhesion between layers, and has excellent transparency and conductivity.

Claims (1)

(57) [Claims] 1. A sheet resistance in which a metal oxide thin film layer, a metal thin film layer, and a metal oxide thin film layer are sequentially laminated on a polymer film having an epoxy acrylate ultraviolet curable resin coating layer containing a silane coupling agent on at least one surface. A lamination characterized in that the metal thin film layer is a silver alloy metal thin film layer having a light transmittance of 70% or more and a metal thin film layer containing 3 to 30% by weight of palladium based on the total weight. the film.