JP3879178B2 - Conductive low reflection laminate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly belongs to the technical field of transparent conductive films and conductive low-reflection films used for displays.
[0002]
[Prior art]
As the transparent conductive film, ITO (Indium Tin Oxide) is mainly used. However, it is optically difficult to achieve both high light transmittance and low resistance, and in particular, it is a serious problem in low-temperature film formation such as when a plastic film is used.
[0003]
The low-reflection film is formed in the outermost layer or a position according to it in a display such as a liquid crystal display (LCD) or a cathode ray tube (CRT), and the display is difficult to see due to reflection of external light such as a fluorescent lamp or sunlight. It is used to prevent this. That is, it refers to a film having a function of reducing the reflectance of visible light on the display surface. Until now, it has been studied to reduce the light reflectance in the visible region by laminating films made of materials having different refractive indexes. In general, an oxide such as silicon oxide, which is a low refractive material, and titanium oxide, which is a high refractive material, is used as a material, and an inorganic multilayer low reflective film is formed in consideration of the refractive index and film thickness.
[0004]
However, in many apparatuses having a display, it is desirable to provide an electromagnetic wave shielding film for shielding electromagnetic waves flying from the outside or preventing leakage of electromagnetic waves generated from the inside of the apparatus.
[0005]
Therefore, it is configured by using ITO for the high refractive index layer of the inorganic multilayer low reflection film, or by laminating ITO thin films on the front and back of the Ag thin film (base material / ITO layer 1 / silver layer / ITO layer 2). Multilayer films are being studied.
[0006]
However, all of the above-described configurations are composed of three or more layers, so that the cost is high and the possibility of a low yield is very high due to the large number of layers.
[0007]
[Problems to be solved by the invention]
The present invention has been made by paying attention to the above-mentioned problems. It achieves both high light transmittance and low resistance, which are difficult to achieve with the ITO 1 layer in terms of the function of the transparent conductive film. In terms of the function of the film, it is an object to provide a laminate having both a low light reflectivity and a low resistance with two layers.
It is an object of the present invention to provide a laminate having a two-layer structure, which has functions of high conductivity, high light transmittance, and low reflectance.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is an electroconductive low-reflection laminated body in which a metal thin film layer / ceramic thin film layer is laminated in this order on a plastic film substrate, and the metal thin film layer comprises an alloy of gold and silver. becomes, and the ceramic thin film layer, tin oxide, a conductive low reflective laminate which is characterized by comprising a mixed oxide of cerium oxide.
[0009]
The invention according to claim 2 is the conductive low-reflection laminate according to claim 1, wherein a hard coat is formed between the substrate and the metal thin film layer.
[0010]
A third aspect of the present invention is the conductive low-reflection laminate according to the first or second aspect, wherein an antifouling layer is formed on the opposite side of the ceramic thin film layer from the metal thin film layer.
[0013]
The present invention is described in detail below.
The high light transmittance and low light reflectance performance of the laminate of the present invention is exhibited by the optical properties of the ceramic thin film layer and the metal thin film layer. Therefore, although the thickness of each layer is not specifically mentioned in the present invention, it is not only the subject of the invention in the present invention, and the laminate obtains high light transmittance and low light reflectance. Therefore, it goes without saying that adjustment of the film thickness of each layer is necessary, and if the material is changed as in the present invention, further adjustment of the film thickness is necessary to obtain high light transmittance and low light reflectance. Needless to say.
[0014]
In the present invention, the ceramic thin film is an inorganic compound thin film, which is a thin film made of oxide, sulfide, fluoride, nitride or the like.
[0015]
Specific examples of oxides include indium oxide, zinc oxide, and tin oxide, or mixed oxides of two or three of them. Any material may be used depending on the purpose and application. good. For example, in addition to the indium oxide, zinc oxide, and tin oxide, there are Group III, Group IV, Lanthanoid oxides such as gallium, magnesium, titanium, aluminum, silicon, and cerium, or mixed oxides thereof.
[0016]
Depending on the film formation method, a non-stoichiometric film may be formed, so that indium oxide, zinc oxide, tin oxide, indium oxide, zinc oxide, tin oxide, gallium, magnesium, titanium Group III, IV, and lanthanoid oxides such as aluminum, silicon, and cerium do not necessarily have a film composition with an elemental composition ratio by a normal chemical reaction. Even if the composition changes continuously or intermittently in one film depending on the film direction, it does not matter as long as it is composed of layers satisfying the above conditions.
Further, a film composition intended by the present invention can be used even if it contains impurities by other components within 10% without departing from the characteristics of the film having this property.
[0017]
The metal thin film layer according to the present invention may be made of any material as long as it is excellent in conductivity. Examples thereof include gold, silver, copper, and alloys thereof. Among these, those mainly composed of silver are excellent in terms of conductivity and optical properties.
Moreover, even if it contains impurities by components other than gold, silver and copper within 10% without departing from the characteristics of the film having this property, it can be said to be a film composition intended by the present invention.
[0018]
The substrate according to the present invention may be made of any material, and is not limited to a flat plate shape but may have any shape, and may or may not be flexible. And plastic film. Here, the plastic means an organic substance and a polymer.
[0019]
The film forming method according to the present invention may be any method as long as the target thin film can be formed, but film forming methods such as sputtering, vapor deposition, ion plating, and CVD (chemical vacuum film forming method) are suitable. Yes.
[0020]
As used in the present invention, a laminate in which a metal thin film layer / ceramic thin film layer is laminated in this order on a substrate means that the metal thin film layer / ceramic thin film layer is continuously formed on the substrate as a result. Any treatment or film formation on both sides or one side of the substrate and the opposite side of the ceramic thin film layer to the metal thin film layer may be used as long as the target properties are not substantially adversely affected. no problem.
[0021]
For example, a layer such as a hard coat, an oxygen and water vapor barrier film, or an adhesion layer may be interposed between the substrate and the metal thin film layer. Further, a layer such as a water repellent layer or an antifouling layer may be formed on the opposite side of the ceramic layer from the metal thin film layer.
The metal thin film layer and the ceramic thin film layer need not be pre-treated, post-treated, or surface-treated at all, but may be subjected to treatment (plasma treatment, ion bombardment treatment, etc.) as necessary.
DETAILED DESCRIPTION OF THE INVENTION
[0022]
Embodiments will be described with reference to examples.
In FIG. 1, the laminated body Example of this invention is shown. Each of the metal thin film layer and the ceramic thin film layer is configured in consideration of conditions necessary for designing an optical film such as a film thickness, a refractive index, and an absorption coefficient.
【Example】
[0023]
A PET (polyethylene terephthalate) film having a thickness of 100 μm was used for the substrate, a tin oxide or cerium oxide mixed oxide was used for the ceramic thin film layer, and an alloy of silver and copper was used for the metal thin film layer.
[0024]
The oxide ratio of the ceramic thin film was tin oxide: cerium oxide = 95: 5% by weight, and the metal thin film layer was mixed with silver: copper = 98: 2 atomic%. As the film forming method, a DC (direct current) magnetron sputtering method was used for the metal thin film layer, and a plasma assist EB (electron beam) evaporation method was used for the ceramic film. The target film thickness of each layer was about 30 nm for the ceramic thin film layer and about 7 nm for the metal thin film layer.
[0025]
A graph of light transmittance and light reflectance of the formed laminate is shown in FIG. 2 together with that of the PET film as the substrate. Each value at a wavelength of 550 nm is 83.3% (base material only: 86.0%) and light reflectivity of 0.8% (base material only: 6.7%), respectively. A transmittance and a low reflectance were obtained.
[0026]
Moreover, when the surface resistance of the laminated body was measured, it was 15 Ω / □ (by the four-terminal method in consideration of the film thickness and shape). This resistance value is extremely low considering the film thickness and light transmittance.
[0027]
FIG. 3 shows the analysis results in the depth direction by X-ray photoelectron spectroscopy in order to clarify that the laminate has a two-layer structure. In the analysis, Sn indicating a ceramic thin film layer, Ag indicating a metal thin film layer, and C indicating a PET film as a substrate were analyzed. From this measurement result, it was clarified that the laminate has a two-layer structure.
【The invention's effect】
[0028]
According to the laminated body of the present invention, the laminated body is formed in the order of the metal thin film layer / the ceramic thin film layer on the substrate in consideration of the conditions necessary for the design of the optical film such as the film thickness, refractive index, absorption coefficient, etc. This makes it possible to achieve both high light transmittance and low resistance, both of which are difficult to achieve with the ITO 1 layer in terms of the function of the transparent conductive film. Further, in terms of the function of the conductive low reflection film, the number of layers is as low as two layers. A laminate having both light reflectivity and low resistance can be obtained. In addition, since the number of layers is small, a dramatic cost reduction and a marked improvement in yield can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an embodiment of the present invention.
FIG. 2 is a graph showing light transmittance and light reflectance of an example.
FIG. 3 is a graph showing the results of depth direction analysis by photoelectron spectroscopy showing that an example has a two-layer structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Metal thin film layer 3 ... Ceramic thin film layer

Claims (3)

A conductive low-reflection laminate that is laminated in the order of a metal thin film layer / ceramic thin film layer on a plastic film substrate, the metal thin film layer is made of an alloy of gold and silver, and the ceramic thin film layer is A conductive low-reflection laminate comprising a mixed oxide of tin oxide and cerium oxide . The conductive low-reflection laminate according to claim 1, wherein a hard coat is formed between the substrate and the metal thin film layer. 3. The conductive low reflection laminate according to claim 1, wherein an antifouling layer is formed on the opposite side of the ceramic thin film layer from the metal thin film layer.

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