JPH0456405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a transparent conductive laminate. More specifically, it is a thin film made of an organic polymer on a transparent conductive layer mainly composed of indium oxide formed on a substrate.
The present invention relates to a transparent conductive laminate formed by laminating films of 0.5 μm or less.

Transparent conductive layers are used in contact with semiconductor materials such as photoconductors and phosphors, in contact with organic electronic materials such as liquid crystals, and recently as electrodes in electrochromism. In recent years, its range of applications has been increasing, including its use as an auxiliary electrode for photochemical reactions.

Particularly recently, it has been used as an essential electrode material for recording and display devices in op-electronics applications.

(Prior art) Indium oxide (In ₂ O ₃ ) systems are produced by vapor deposition or sputtering using an indium-tin alloy doped with an appropriate amount of tin oxide (SnO ₂ ) or indium oxide/tin oxide mixed oxide (ITO) as a starting material. Formed by law, etc.

In addition, tin oxide (SnO ₂ ) systems are doped with an appropriate amount of antimony oxide (Sb ₂ O ₃ ), and the substrate temperature is increased to 400°C to 500°C mainly by spraying with chloride (tin chloride solution).
Created at high temperatures of ℃.

(Problems) However, transparent conductive films containing indium oxide as a main component have no chemical durability against acids and alkalis, and their resistance value increases due to the narrow potential range in which they can be used in aqueous electrolytes and changes in usage environmental conditions. A major drawback is that it drifts.

The usage environment conditions here refer to the indoor environment in which an electrical product or the like in which the transparent conductive film is used as a component is used. Electrical products generally range from -10℃ to +60℃
It is required to operate continuously and stably for a long period of time without malfunctions, even when the temperature environment changes by about 30 degrees Fahrenheit or the humidity environment changes from about 50% to 95% relative humidity.
A transparent conductive film whose resistance value fluctuates (drifts) in response to changes in environmental conditions naturally has a limited range of use.

Furthermore, although the tin oxide film is superior to the indium oxide film in terms of the above-mentioned stability, it cannot be said to be perfect yet. Furthermore, in the case of tin oxide-based films,
It is necessary to raise the substrate temperature to 400° C. to 500° C., and the conductivity obtained is approximately an order of magnitude worse than that of indium oxide films, and the transparency is also poor.

(Means) In order to overcome such problems, the present inventors have made extensive studies and found that a transparent conductive layer with a thickness of 0.5 μm or less made of an organic polymer is formed on a transparent conductive layer mainly composed of indium oxide formed on a substrate. By laminating films, the environmental stability is significantly improved without any loss in the properties of the transparent conductive film, especially its transparency and conductivity, and it is virtually unaffected by changes in the environment in which it is used (temperature changes, humidity changes). There is no change in resistance value, and stability over time under the same environmental conditions (e.g. temperature 40°C, relative humidity 80%) is good, making it possible to almost eliminate drift in the resistance value of the transparent conductive film. It became.

In addition, especially when the purpose is to improve environmental stability, the oxygen transparency coefficient is 5 × 10 ^-10 cc・
A remarkable effect was found when using a membrane formed from an organic polymer smaller than cm/ ^cm2・sec・cmHg.
The present invention was achieved by discovering that a transparent conductive laminate having excellent transparency and stable resistance can be obtained.

That is, the present invention provides: (1) a transparent conductive layer mainly composed of indium oxide formed on a substrate;
A transparent conductive laminate formed by laminating films of 0.5 μm or less, especially (2) the organic polymer has an oxygen permeability coefficient of 5×
The laminate according to item 1 above, which is an organic polymer having an Hg of less than 10 ^-10 cc·cm/cm ² ·sec·cmHg.

The substrate in the present invention may be an inorganic substrate such as quartz glass or alkali glass, a natural fiber material such as paper or pulp, or an organic substrate such as a normal sheet, film, molded body, or fiber, depending on the purpose. .

Typical materials for organic substrates include polyethylene terephthalate film, polyethylene naphthalate film, polyamide film,
Thermoplastic resins such as polyimide film, polysulfone film, polyether sulfone film, polyetherimide film, polyarylate film, polyether ether ketone film, and polycarbonate film are preferably used.

In addition, the transparent conductive layer containing indium oxide as a main component in the present invention refers to In ₂ O ₃ alone or a few percent of In ₂ O ₃
A conventionally well-known transparent conductive layer containing _SnO2 ,
or cadmium (Cd) whose main component is In ₂ O ₃ ,
A transparent conductive layer containing a small amount of impurities such as antimony (Sb). Such a transparent conductive layer can be easily formed by conventionally well-known vacuum deposition methods, sputtering methods, ion plating methods, reactive vapor deposition methods, reactive sputtering methods, and the like.

If we talk about the vacuum evaporation method, for example, a few percent
In ₂ O ₃ ^{containing SnO} ₂ of
A thin film of In ₂ O ₃ containing SnO ₂ in a low oxidation state can be deposited on a substrate. By subjecting such a thin film to an appropriate oxidation treatment such as heat treatment, a transparent conductive film containing In ₂ O ₃ as a main component can be obtained. The thickness of the transparent conductive film containing In ₂ O ₃ as a main component can be selected from various thicknesses depending on the application. Moreover, by controlling the film thickness and degree of oxidation, a transparent conductive film having arbitrary transmittance and resistance value can be formed.

It is known that In ₂ O ₃ doped with an appropriate amount of Sn ₂ O ₂ exhibits a specific resistance value of about 8×10 ⁻⁴ Ωcm to 2×10 ⁻³ Ωcm. For example, a transparent conductive film whose main component is In ₂ O ₃ with a thickness of 200 Å is 400 Å.
It has a surface resistance ranging from Ω/mouth to approximately 1000Ω/mouth. For example, when it is formed on a polyester film with a thickness of 50 μm, the visible light transmittance will be in the range of about 80% to 86% at 550 nm.

Furthermore, indium oxide In ₂ O ₃ as used in the present invention does not specify the compound itself, but InxOy
It is used as a general term for (0≦x2, 0≦y≦3). Therefore, indium oxide in the present invention
In ₂ O ₃ is a generic term that comprehensively includes lower oxides of indium, non-stoichiometric compounds, and the like. Similarly to the above, tin oxide Sn ₂ O ₂ is a general term for compounds of tin and oxygen.

The organic polymer film laminated on the transparent conductive film containing In ₂ O ₃ as a main component is an organic polymer that is soluble in a suitable solvent, especially an organic solvent, and provides a uniform and transparent coating film. It can be formed from For example, acrylate resins such as polymethyl methacrylate and polyethyl methacrylate, acrylic resins such as polyacrylonitrile and polymethacrylonitrile, fluororesins such as vinyl fluoride/hexafluoropropylene copolymer, vinyl chloride, and vinyl acetate. Resins such as vinyl resins, polyvinyl alcohol resins, polyvinyl butyral resins, phenoxy resins, polycarbonate resins, polyester resins, polyurethane resins, and mixtures and copolymers thereof are preferably used.

In particular, when environmental stability (low temperature and temporal drift of resistance value) is required for a transparent conductive film containing In ₂ O ₃ as the main component, a film made of an organic polymer has a low oxygen permeability coefficient. , 5×10 ^-10 cc・cm/cm ²・
It is preferred to use an organic polymer membrane formed from an organic polymer having a property of less than sec.cm ₈ Hg.

Examples of organic polymers that meet this requirement include polystyrene resin, polycarbonate resin, polyvinyl butyral resin, styrene/acrylonitrile copolymer resin, vinyl acetate resin, polymethyl methacrylate resin, vinyl chloride resin, and vinylidene chloride/acrylonitrile copolymer resin. Examples include polyacrylonitrile resin, polymethacrylonitrile resin, and polyvinyl alcohol resin. Regarding the oxygen permeability of organic polymers, for example, see Fumio Osawa's ``Function of Membranes,'' Kyoritsu Kagaku Library, published in 1978.
This can be determined using the table etc. on pages 176 to 178. Polyacrylonitrile resins and polymethacrylonitrile resins have particularly low permeability.

What kind of effects does a film made of organic polymer have?
It is not clear whether this contributes to the stabilization of the transparent conductive film whose main component is In ₂ O ₃ , but by controlling the permeation of oxygen to some extent, the oxidation state of the transparent conductive film whose main component is In ₂ O ₃ can be improved. It is thought that this keeps the surface condition constant and stabilizes it.

The thicker the film made of organic polymer, the greater the stabilizing effect. However, the thicker the transparent conductive film is, the higher the surface resistance, which is a characteristic of the transparent conductive film, does not meet the intended use of the transparent conductive film.

The film thickness of the organic polymer is determined by balancing these two effects. The thickness is preferably 0.5 μm or less, particularly preferably 0.3 μm or less. In particular, when the demand for conductivity is high, a thickness of 0.1 μm or less is most preferably used.

Further, the lower limit of the film thickness of the organic polymer is not particularly limited as long as its stabilizing effect is exhibited, but the lower limit of the effect is 50 Å or more, preferably 100 Å.
A film thickness greater than or equal to that is required.

In this case, if the same level of stabilizing effect is expected, the film thickness can be made thinner by using an organic polymer with a lower oxygen permeability. In this way, the organic polymer film according to the present invention can appropriately control the stability and conductivity of the transparent conductive film containing In ₂ O ₃ as the main component by appropriately selecting its oxygen permeability and film thickness. things are possible.

A simple method for forming a film made of an organic polymer is to select an appropriate resin, dissolve it in a solvent that can dissolve the resin at an appropriate concentration, apply it, and then evaporate the solvent to form a film. It is. Specifically, there are methods using a bar coater, doctor knife, etc., methods such as spin coating, spraying, etc., and coating methods using equipment such as a gravure roll coater, Meyer bar coater, reverse roll coater, etc. Depending on the shape of the sample, etc. It is sufficient to select an appropriate method.

By controlling the properties and thickness of the organic polymer films laminated in this manner, a transparent conductive laminate having desirable environmental stability, transmittance, and display resistance can be obtained.

That is, in the present invention (1) a transparent conductive layer formed on a substrate and made of an organic polymer on a transparent conductive layer containing indium oxide as a main component;
A transparent conductive laminate made of layers of 0.5 μm or less, and (2) a film made of an organic polymer, has an oxygen permeability coefficient of 5×10 ^-10 cc・cm/cm ²・sec・cmHg. The laminate described in item 1, which is a film with a thickness of 0.5 μm or less formed from a small organic polymer, has environmental stability and stability over time without impairing the properties of the transparent conductive layer whose main component is indium oxide. This provides a transparent conductive laminate with excellent properties.

The present invention will be specifically explained below with reference to Examples.

Method for measuring film thickness of organic polymer film Cut the sample coated with organic polymer into a size of 10 cm x 10 cm, then further cut into about 2 cm x 2 cm, and add 10 to 20 ml of a solvent capable of dissolving the organic polymer. Elute the organic polymer in a glass container for 30 minutes.
Further elute completely in an ultrasonic cleaner for 10 minutes. The remaining substrate, such as a PET film, is removed from the solution while being washed with a solution, and the container is left to stand and evaporated to dryness. The amount of organic polymer is determined by FT-NMR method using the dry residue, and the thickness is determined by converting it into area.

Example 1 A polyethylene terephthalate film with a thickness of 75 μm was used as a substrate and was deposited on the substrate by sputtering method.
A transparent conductive layer was formed whose main component was In ₂ O ₃ containing several percent of Sn ₂ O ₂ . The sputtering conditions are shown in the table below.

Target: In ₂ O ₃ ; 93 mol%, Sn ₂ O ₂ ; 7 mol
% Gas: Ar; 90%, O ₂ ; 10% Pressure: 5×10 ^-3 Torr Output: 300W Substrate temperature: 40°C The transparent conductive film formed in this way has a film thickness of 400
Å, surface resistance 350Ω/hole, visible light transmittance 80% at 550nm. A polyacrylonitrile thin film layer with a thickness of 500 Å made of polyacrylonitrile was laminated on this transparent conductive film.

The polyacrylonitrile thin film layer was obtained by applying an N.N' dimethylformamide solution in which 1% by weight of polyacrylonitrile was dissolved using a bar coater, and then drying at 130°C for 2 minutes.

The surface resistance of the transparent conductive laminate made of polyacrylonitrile is 400Ω/hole, and the visible light transmittance is
It was 82%.

Place the obtained laminate in a 90°C oven for 100°C.
The surface resistance was measured after a period of time, and the rate of change in surface resistance was within 10% of the initial value.

Example 2 A polymethacrylonitrile thin film layer with a thickness of 700 Å was formed on the In ₂ O ₃ transparent conductive film containing Sn ₂ O ₂ used in Example 1. Polymethacrylonitrile thin film layer contains 0.8% by weight of polymethacrylonitrile
Coat a mixed solvent of 1 part of dissolved cyclohexanone and 1 part of methyl ethyl ketone with a bar coater,
Thereafter, it was dried at 130°C for 2 minutes. The resulting transparent conductive laminate in which polymethacrylonitrile was laminated had a surface resistance of 430 Ω/hole and a visible light transmittance of 81%.

Place the obtained laminate in an oven at 90℃ for 100 minutes.
The resistance was measured after a period of time, and the rate of change in surface resistance was within 10% of the initial value.

Comparative Example 1 A transparent conductive layer composition mainly composed of In ₂ O ₃ containing several percent of SnO ₂ was formed on a polyethylene terephthalate film in the same manner as in Example 1, and then placed in an oven at 90°C for 100 hours. The subsequent surface resistance was measured. The rate of change in surface resistance varied by more than 50% from the initial value.

Comparative Example 2 A transparent conductive layer mainly composed of In ₂ O ₃ containing several percent of SnO ₂ was formed on a polyethylene terephthalate film in the same manner as in Example 1, and a transparent conductive layer with a thickness of 800 Å was formed on the polyethylene terephthalate film.
A transparent conductive laminate was obtained by laminating thin film layers formed from dimethylsiloxane condensates.

The surface resistance of the obtained transparent conductive laminate was 420
Ω/It was hot with my mouth. The obtained laminate was placed in an oven at 90°C and the surface resistance was measured after 100 hours. The rate of change in surface resistance varied by more than 50% of its initial value.

Example 3 Using a polyethylene terephthalate film having a thickness of 75 μm as a substrate, a transparent conductive layer mainly composed of In ₂ O ₃ containing SnO ₂ was formed on the substrate by a sputtering method. The sputtering conditions are shown in the table below.

Target: In 95% by weight, Sn 5% by weight Gas: Ar; 80%, O ₂ 20% Pressure: 5×13 ^-3 Torr Output: 400W Substrate temperature: 40℃ Transparent conductive film formed in this way is film thickness 230
Å, surface resistance was 470Ω/mouth, and visible light transmittance was 84%. A thin film made of polymethyl methacrylate with a thickness of 700 Å was formed on the obtained transparent conductive film.

The 700 Å thick polymethyl methacrylate layer is
A transparent conductive film was spin-coated with a solvent consisting of 1 part of toluene and 0.5 parts of methyl ethyl ketone containing 1.5% by weight of polymethyl methacrylate, and then dried at 120° C. for 2 minutes.

The surface resistance of the obtained transparent conductive laminate was 500
Ω/mouth, visible light transmittance was 85%.

The surface resistance of the transparent conductive laminate was measured after 100 hours by placing it in an oven at 90°C, and the rate of change from the initial value remained within 20%. Also, temperature
The surface resistance was measured after being left in an atmosphere of 22℃ and 45% humidity for one year, but the rate of change in surface resistance was 15% from the initial value.
It was within %.

Comparative Example 3 A polyethylene terephthalate film formed in the same manner as in Example 3 containing a substrate and SnO ₂
A structure comprising a transparent conductive layer containing In ₂ O ₃ as a main component was evaluated in the same manner as in Example 3.

The rate of change in surface resistance after 100 hours of heat treatment at 90°C was over 70%, and the rate of change in surface resistance after being left indoors for one year was approximately 50%.

Example 4 A polyethylene terephthalate film having a thickness of 75 μm was used as a substrate, and a transparent conductive layer mainly composed of In ₂ O ₃ containing several percent of SnO ₂ was formed on the substrate by a sputtering method. The sputtering conditions are as follows.

Target: In ₂ O ₃ ; 93 mol%, Sn ₂ O ₂ ; 7 mol
% Gas: Ar; 95%, O ₂ ; 5% Pressure: 5×10 ^-3 Torr Output: 250W Substrate temperature: 30℃ The transparent conductive film formed in this way has a thickness of 220 mm.
Å, surface resistance of 440Ω/hole, and visible light transmittance of 85%.

A thin film layer having a thickness of 800 Å made of acrylonitrile-styrene copolymer (molar ratio acrylonitrile/styrene = 26/74) was laminated on the transparent conductive film.

A membrane made of acrylonitrile-styrene copolymer is made of acrylonitrile-styrene copolymer.
A solution of a mixed solvent (consisting of 2 parts of cyclohexanone, 1 part of methyl ethyl ketone, and 1 part of toluene) in which 0.8 wt% was dissolved was coated using a bar coater, and then dried at 120° C. for 2 minutes to obtain a sample.

The surface resistance of such a transparent conductive laminate is 510Ω/
The visible light transmittance was 86%.

The obtained transparent conductive laminate was placed in a chamber maintained at 60° C. and 95% humidity, and the surface resistance was measured after 200 hours, and the rate of change in surface resistance was 15% or less.

Comparative Example 4 Example 4 except that an 800 Å thick layer of poly(4-methylpentene-1) was laminated instead of using the acrylonitrile-styrene copolymer film.
A transparent conductive structure was obtained in the same manner as above. poly(4
-Methylpentene-1) 800 Å thick layer contains 0.8% by weight of poly(4-methylpentene-1)
The dissolved cyclohexene solution was coated with a bar coater and dried at 120° C. for 3 minutes to obtain a coating. The surface resistance of the obtained transparent conductive laminate was 470Ω/hole, and the visible light transmittance was 86%.

As a result of evaluating this transparent conductive laminate in the same manner as in Example 4, the rate of change in surface resistance was 80%.

Claims (1)

[Claims] 1 A transparent conductive layer mainly composed of indium oxide formed on a substrate has an oxygen permeability coefficient of 5×
10 ^-10 A transparent conductive laminate made of layers of organic polymer films with a thickness of 50 Å or more and 0.5 μm or less at a temperature smaller than ² sec cmHg.