JPH0562064B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a transparent conductive film which is made of a synthetic resin film as a base material and is flexible and has excellent moisture permeability resistance. (Prior art) Products in which a transparent conductive thin film is formed on a transparent substrate such as glass or plastic are used for liquid crystal display elements and EL devices.
Demand is increasing for use in electrical engineering devices such as devices and solar cells, as well as anti-fog glass and antistatic materials. Conventionally, as a transparent conductive film, a film in which a transparent conductive film containing a low oxide of indium metal as a main component is formed on the surface of a polyester film has been proposed, for example, as described in JP-A-54-8670. However, when used as an electrode for an EL element, for example, the function of protecting the EL element from moisture was insufficient. (Problems to be Solved by the Invention) The present invention has been made for the purpose of eliminating the above-mentioned conventional drawbacks, and providing a transparent conductive film that does not impair transparency and has extremely good moisture permeability resistance. be. (Means for Solving the Problems) In the present invention, polyvinyl chloride, polystyrene, polyester, polyvinyl butyral, polyethylene, polypropylene, polyamide, cellophane, etc. are preferably used as the transparent synthetic resin film of the base material. A medium polyethylene terephthalate (PET) film is particularly preferably used in terms of dimensional stability, mechanical strength, and heat resistance. In addition, the transparent synthetic resin film has a thickness of 10~
The film preferably has a flexibility of 300 μm, and more preferably has a thickness of 50 to 200 μm. In order to deposit an oxidizing composition onto a transparent synthetic resin film, a winding process using a cooling roll is normally required, but if the thickness of the transparent synthetic resin film is less than 10 μm, wrinkles and cracks may occur. If the thickness exceeds 300 μm, the flexibility becomes poor and continuous winding becomes difficult. A thin, transparent insulating oxide layer with excellent moisture permeability is formed on at least one side of the transparent synthetic resin film. This transparent insulating oxide layer consists of SiO ₂ ,
The molar ratio of Al ₂ O ₃ and MO (M represents divalent metals such as Mg, Ca, Sr, and Ba) is (SiO ₂ ): (Al ₂ O ₃ ):
(MO) = 1:0.2~0.6:0.2 _~ 0.8, or _SiO2 , _{B2O3 ,} BaO, _Al2O3 in molar ratio _{( SiO2} ):( _B2O3 ): (BaO+ _Al2O3 )= ₂ ~
The composition is 8:0.5 to 4:1. When the molar ratio of the transparent insulating oxide layer is out of the above range, phase separation tends to occur and moisture permeation resistance decreases. If the content of oxides such as PbO and ZrO ₂ as impurities in the above composition is 5% by weight or less, no extreme deterioration in moisture permeation resistance is observed, and the transparent conductive film of the present invention with excellent moisture permeation resistance can be produced. If so, it is desirable to keep the impurities within the above range. A thin, transparent insulating oxide layer made of the oxide of the above composition may be formed by any known method such as sputtering, vacuum evaporation, or ion plating. The most preferred method for forming a transparent insulating oxide layer on the surface of a transparent synthetic resin film is sputtering, and by using the above composition as the sputtering target, a thin and transparent amorphous layer of approximately the same composition can be formed. An insulating oxide layer can be formed. A thin and transparent insulating oxide layer having the above composition can also be formed by vacuum evaporation.
In the case of vacuum evaporation, it is said to be difficult to form a thin film layer using mixed substances having different vapor pressures with the same composition. However, the present inventors have confirmed that if the above composition is melted and solidified in advance in an electric furnace and then used as an evaporation material and evaporated using an electron gun heating method, a deposited film having approximately the same range can be obtained. . Further, a deposited film having the above composition can also be formed by a flash deposition method which is generally used when vacuum depositing a mixture. In the present invention, the adhesion of the transparent insulating oxide layer to the transparent synthetic resin film is good, and the transparency is also good, regardless of whether the sputtering method, vacuum evaporation method, or ion plating method is used. Another feature of the present invention is that curling does not pose a major problem in a film-like transparent synthetic resin body in which a transparent insulating oxide layer is formed by a sputtering method or the like. This is considered to be because the residual stress in the transparent insulating oxide layer is small in the system having the composition of the present invention. The thickness of the transparent insulating oxide layer is preferably in the range of 0.01 to 0.5 μm, more preferably 0.05 to 0.3 μm in order to have good flexibility and adhesion.
It is best to keep it within the range. The thickness of the transparent insulating oxide layer needs to be 0.01 μm or more because it will not form a uniform continuous film unless it is 0.01 μm or more. Also, if the film thickness exceeds 0.5 μm, transparency will not be impaired, but
Curling of the film-like transparent synthetic resin body may become a problem, and the film may easily crack or peel. To form a transparent insulating oxide layer by vacuum evaporation method or ion plating method, usually 2×
It is carried out under a vacuum atmosphere of 10 ^-3 torr or less, but in order to avoid deterioration of performance due to the contamination of impurities,
It is preferable to carry out under a vacuum atmosphere of 10 ^-4 torr or less. A transparent conductive film containing indium oxide as a main component is formed on the transparent insulating oxide layer.
This transparent conductive film is formed by a vacuum deposition method, an ion plating method, a sputtering method, a reactive vapor deposition method, a reactive sputtering method, or the like. For example, to explain the vacuum evaporation method, for example, In ₂ O ₃ containing about 10% SnO ₂ is used as the evaporation source, and the degree of vacuum in the vacuum chamber is set to 10 ^-4 to ^{10 -5} torr.
A thin film of In ₂ O ₃ containing SnO ₂ in a low oxidation state can be formed by resistive heating or vapor deposition using an electron gun. The thickness of the transparent thin film containing In ₂ O ₃ as a main component can be selected from various thicknesses depending on the application. Further, by controlling the film thickness and degree of oxidation, a transparent conductive thin film having arbitrary transmittance and resistance value can be formed. (Example) Examples of the present invention are shown below. Example 1 A mixture of oxides with a molar ratio of SiO ₂ , Al ₂ O ₃ , and CaO of 5:2:3 was melted and solidified in an electric furnace and heated with an electron gun under a vacuum of 5×10 ^-5 torr. A 0.1 μm thick transparent insulating oxide layer was formed on a 100 μm thick polyethylene terephthalate (PET) film by heating and evaporating the film. The thickness of the transparent thin film layer was measured using a crystal oscillation type monitor. The composition of the transparent insulating oxide layer was analyzed using an X-ray microanalyzer and was found to be approximately the same as the composition of the original mixture. A transparent conductive layer mainly composed of In ₂ O ₃ containing 7% by weight of SnO ₂ was formed on this transparent thin film layer by a sputtering method. The sputtering conditions were a pressure of 5 x 10 ^-3 torr, a mixed gas of 90% Ar and 10% O ₂ , and an output of 300W. The transparent conductive film thus formed had a film thickness of 0.05 μm, a surface resistance of Ω/cm ² ,
The visible light transmittance was 82%. The adhesion between the formed insulating oxide layer and the transparent conductive film was checked according to JIS D0202 and was found to be very good. Moisture permeability is 40℃, relative humidity is 90%, JIS Z0208
(Gravimetric method using Cupp). Visible light transmittance (567 nm) was measured according to JIS K-6714. These results are shown in Table 1. Examples 2 to 7 Instead of the oxide mixture composition of Example 1, the first
It is the same as Example 1 except that the composition in the specific mixing range shown in the table was used. These results are also shown in Table 1. Comparative Examples 2 to 5 Instead of the oxide mixture composition of Example 1, the first
Example 1 except that the composition shown in the table was used.
is the same as These results are also shown in Table 1. Comparative Example 1 Without forming the insulating oxide layer of Example 1,
This example is the same as Example 1 except that the transparent conductive layer of Example 1 was directly formed on a polyethylene terephthalate (PET) film having a thickness of 100 μm. These results are also shown in Table 1.

【table】

【table】
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〓Visible light transmittance: 88%
As is clear from Table 1, in the case of the Examples of the present application, compared to the Comparative Examples, both transparency and
It has extremely good moisture permeability without impairing conductivity, and especially when an insulating oxide layer is formed from a specific oxide mixture composition, it has extremely good moisture permeability and gas permeation resistance. It also has excellent conductivity. (Effects of the invention) The transparent conductive film of the present invention with excellent moisture permeability resistance is
A transparent insulating oxide layer is formed on at least one side of the transparent synthetic resin film, and a transparent conductive film containing indium oxide as a main component is formed on the layer, so that the transparent conductivity of the film is improved. It has excellent moisture resistance and resistance to permeation of gases such as oxygen.

Claims (1)

[Claims] 1. On at least one side of a transparent synthetic resin film,
The molar ratio of SiO ₂ , Al ₂ O ₃ , and MO (M represents divalent metals such as Mg, Ca, Sr, and Ba) is (SiO ₂ ):
( _Al2O3 ):( _MO )=1:0.2 _~ 0.6:0.2 _~ 0.8 composition or SiO2, _{B2O3 ,} BaO, _Al2O3 in molar ratio, ( _SiO2 ): (B ₂ O ₃ ): (BaO + Al ₂ O ₃ )=2
Consisting of a composition with a ratio of ~8:0.5 to 4:1,
A transparent conductive film with excellent moisture permeability resistance, which is formed by forming a transparent insulating oxide layer and forming a transparent conductive film containing indium oxide as a main component on the layer. 2. A transparent conductive film with excellent moisture permeability resistance according to claim 1, wherein the insulating oxide layer is formed by a sputtering method. 3. The transparent conductive film with excellent moisture permeability resistance according to claim 1, wherein the insulating oxide layer is formed by a vacuum evaporation method. 4. The transparent conductive film with excellent moisture permeability resistance according to claim 1, wherein the insulating oxide layer is formed by an ion plating method.