JPH08290515A - Transparent and electrically conductive film and its preparation - Google Patents

Abstract

PURPOSE: To provide good electrical conductivity and transparency and excellent oxygen and steam barrier properties. CONSTITUTION: This transparent and electrically conductive film is characterized by forming a transparent inorg. barrier thin film with substantially non- permeable properties to oxygen and steam and a thickness of 10-100nm on both faces of a transparent film base and forming furthermore a transparent conductive thin film with a thickness of 20-400nm on one of the inorg. barrier thin film.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a transparent film substrate having transparent inorganic barrier thin films formed on both sides thereof, and a transparent conductive thin film formed on one of the inorganic barrier thin films. TECHNICAL FIELD The present invention relates to a transparent conductive film which is electrically impermeable and has good conductivity and transparency, and a method for producing the same.

[0002]

2. Description of the Related Art Due to the widespread popularization of personal computers, word processors, etc., the application and characteristics of liquid crystal display devices are rapidly improving. As the transparent electrode substrate material used for these, glass is generally used.
As an example of a transparent electrode processed on a glass substrate,
For example, a thin layered glass such as tin oxide, or a thin film of a mixture of indium oxide and tin oxide (ITO) I
Known are TO glass, conductive glass on which a conductive metal thin film such as gold and silver is formed, and the like.

However, the glass used as the substrate has drawbacks such as weakness to impact, heavy weight, lack of flexibility, and difficulty in increasing the area, and in order to compensate for these drawbacks, a plastic film or sheet is used as the substrate. The transparent conductive film is also manufactured. The plastic film has advantages such as impact resistance, flexibility, light weight, easy to make large area, and good workability.The transparent conductive film using the plastic film as a substrate is still a liquid crystal. It is used for display devices, touch panels, antistatic films, infrared reflective films, etc.

However, a single plastic film substrate cannot satisfy the various properties such as gas barrier property, water vapor barrier property and solvent resistance. Therefore, a film base material is often subjected to undercoating or surface treatment to form a composite. A known method such as coating or sputtering may be used for compounding, but conventionally compounding by coating has been widely used. However, in the composite by coating, sufficient characteristics could not be obtained due to the limitation of the coating material. In particular, in order to exhibit sufficient barrier properties and reliability, both sides of the film substrate had to be processed with a considerable thickness.

Currently, the conductive thin film used for the transparent conductive film is mainly an ITO thin film which is excellent in both conductivity and transparency and is easy to pattern, and this transparent conductive thin film is used for electronics. Widely used in the display device field. As a method of forming the ITO thin film on a plastic film substrate, a vacuum deposition method,
A sputtering method, an ion plating method, and the like are known, and among them, the vacuum vapor deposition method is often used because of high productivity, inexpensive raw materials, and the like. Further, the magnetron sputtering method is often used because of its good adhesion to a film, good film uniformity, easy control of film quality, and good productivity.

[0006]

In order to impart various properties such as gas barrier property, water vapor barrier property, solvent resistance and the like to a film base material, a coating method is applied to both surfaces of the base material with a considerable thickness. Must. Also, coating only on one side has low reliability, and there are many practical problems. However, when the barrier material is applied to both sides of the substrate with a considerable thickness, bar streaks and uneven coating are generated due to the coating method, which not only impairs the appearance but also greatly affects reliability and yield. Further, when the inorganic barrier layer is formed on only one surface of the substrate film, sufficient characteristics cannot be obtained.
Moreover, the reliability with respect to the generation of minute defects is poor. That is, even if a defect occurs in a part of the barrier layer, the quality characteristics of the entire composite substrate fall to an unacceptable range. Therefore, the present invention provides a transparent conductive film which does not have the above-mentioned drawbacks, has good conductivity and transparency, and has excellent gas barrier property and water vapor barrier property.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of the above-mentioned circumstances, and as a result, formed an inorganic barrier thin film having a specific thickness on both surfaces of a substrate, and further, on one inorganic barrier thin film. It was found that the above-mentioned problems can be solved by forming a transparent conductive thin film having a specific thickness on, and completed the present invention.

That is, the first aspect of the present invention is to form a transparent inorganic barrier thin film having a thickness of 10 to 100 nm, which is substantially impermeable to oxygen and water vapor, on both surfaces of a transparent film substrate. According to a second aspect of the present invention, there is provided a transparent conductive film comprising a transparent conductive thin film having a thickness of 20 to 400 nm formed on the inorganic barrier thin film of
A transparent inorganic barrier thin film that is substantially impermeable to oxygen and water vapor is formed on one side of a transparent film substrate by electron beam evaporation, and the barrier thin film and transparent conductivity are formed on the other side by magnetron sputtering. A method for producing a transparent conductive film, which is characterized by forming a thin film, is included in each of the contents.

The transparent film substrate for forming the transparent conductive film of the present invention is formed of a plastic film and has a thickness of about 20 to 1000 μm, preferably 50 to 2
It is a film having a surface smoothness of about 00 μm, more preferably 75 to 100 μm and a light transmittance of 85% or more, preferably 90% or more. The thickness of the substrate is 50
In the range of up to 200 μm, the light transmittance is 85%.
As described above, a transparent film having a good surface smoothness and a uniform film thickness is easily obtained. Further, when the light transmittance of the substrate is about 90% or more, the transparency of the transparent conductive film is good, the surface property of the thin film is good, and the fine workability such as etching is improved.

The plastic film is not limited to a film made of a single base material, and may be subjected to various undercoats and surface treatments for the purpose of improving adhesion strength, barrier property, solvent resistance and the like. The applied composite film may be used. A known method such as coating, vapor deposition, or sputtering may be used for forming the composite.

Examples of plastics forming the transparent film substrate include, for example, polyarylate (PAR), polyethylene terephthalate (PET), polycarbonate (PC), polyether sulfone (PES), polysulfone, polyamide, cellulose triacetate (T).
AC) and the like, but are not limited thereto. Among the plastics, polyarylate and polycarbonate, which have high transparency and excellent heat resistance, are preferable, and particularly preferable for use in the application of liquid crystal display devices. Particularly preferred are polyarylates and polycarbonates having a substituted or unsubstituted hydroxyphenyl cycloalkane as a bisphenol component and copolymers thereof. Further, these substrate materials are not limited to a single material, and a blend or alloy of two or more kinds can be used.

The inorganic barrier thin film formed on both sides of the transparent conductive film of the present invention has a thickness of 10 to 100 nm,
Preferably 20 to 60 nm, oxygen gas barrier property 5 cc /
m ² / day or less, preferably 1 cc / m ² / day or less, the water vapor barrier properties 5 g / m ² / day or less, preferably 1 g / m ² /
It is a barrier thin film of less than one day. The above-mentioned inorganic barrier thin film means silicon dioxide or a compound containing silicon dioxide as a main component and one or more metal oxides such as silicon monoxide and aluminum oxide, a compound containing aluminum oxide as a main component, and silicon nitride. Alternatively, it is a compound containing this as a main component and one or more kinds of metal nitrides such as aluminum nitride, and specific examples of these compounds include, for example, SiO _x , A1 ₂ O ₃ , SiA1N, and SiA1O.
N, SiMgON, etc. are mentioned.

By forming the above-mentioned inorganic barrier thin film on both sides of the substrate, various characteristics centering on barrier properties,
And reliability is improved. That is, since both surfaces of the substrate are covered with the barrier layer, barrier properties and durability are improved. Further, even if a minute defect occurs on one surface, the barrier layer on the other surface can maintain the characteristics, and the reliability of the entire substrate is improved.

The transparent conductive thin film in the transparent conductive film is selected from conductive metal oxides, and indium oxide is preferably used. The film thickness is 20 to 400 nm, preferably 50 to 200 nm, more preferably 80 to 150 nm, and the light transmittance is 80% or more,
Preferably 85% or more, sheet resistance 100Ω / □ or less,
It is preferably a transparent conductive thin film having a uniform film thickness distribution of 50 Ω / □ or less. The thickness of the transparent conductive thin film is 80 to 15
When it is within the range of about 0 nm, it is easy to adjust both the sheet resistance and the light transmittance within the target range. Further, when the light transmittance of the transparent conductive thin film is about 85% or more, the transparency of the transparent conductive film can be improved.

The metal oxide mainly composed of indium oxide is indium oxide or a main component thereof, specifically, 80% (wt%, the same applies hereinafter) or more, and further 90 to 95.
%, And a compound containing 20% or less, and further 10 to 5% of one or more kinds of other metal oxides such as tin oxide and cadmium oxide. Specific examples of this compound include IT.
O, CdIn ₂ O _{4, and the} like. Among the above-mentioned metal oxides mainly composed of indium oxide, ITO, particularly, 10% or less of tin in terms of metal, preferably 5 to 10%, is preferable from the viewpoint of maintaining high transparency and reducing sheet resistance. .

As described above, the transparent conductive film of the present invention has the sheet resistance and the light transmittance which are equal to or higher than those of the transparent conductive glass. Further, since the transparent film substrate is used, it has features such as impact resistance, light weight, flexibility, easiness of increasing the area, and good workability.
Furthermore, by disposing the gas barrier layer on both sides of the substrate, various characteristics centering on the barrier property and reliability are improved. That is, since both sides of the substrate are covered with the barrier layer, even if a minute defect occurs on one side, the barrier layer on the other side can maintain the characteristics, and the reliability and durability of the entire substrate are improved. .

Next, an example of the method for producing the transparent conductive film of the present invention will be described. As the material used for film formation,
For the transparent inorganic barrier thin film, as described above, other metal oxides mainly composed of silicon oxides such as aluminum oxide, and metal nitrides mainly composed of aluminum oxide or silicon nitride such as aluminum nitride are mixed and burned. A knot is used. For the transparent conductive thin film, indium oxide or a composite oxide sintered body containing this as a main component and another metal oxide such as tin oxide is used. In particular, it is desirable to use a sintered body of ITO (a mixture of indium oxide and tin oxide). As described above, the ratio of indium oxide to tin oxide of ITO is preferably 10% or less of tin in terms of metal.

In the case of the sputtering method, the power source used is preferably a high frequency power source (RF) in the case of a transparent inorganic barrier thin film due to the physical properties of the target, and a direct current source (DC) in the case of a transparent conductive thin film from the viewpoint of productivity. ) Is desirable.
Sputtering is performed by controlling the power input to the target while taking into account the above conditions. In the case of a transparent inorganic barrier thin film, it is desirable to form the film with a power density of RF1 to 4 W / cm ² . If it is less than this, the non-adhesive force becomes insufficient and peeling easily occurs, and if it is more than this, curling becomes severe and insufficient cooling of the target occurs, resulting in damage to the target. The thickness of the barrier thin film is 10 to 100 nm, preferably 20 to 60 nm. DC0.1-2W / cm ^{2 for} transparent conductive thin film
It is desirable to form the film below, more preferably 1.2 W / cm ² or less. When it exceeds, the internal stress of the ITO thin film increases, the curl increases, and peeling easily occurs. On the other hand, the lower limit should be determined in consideration of productivity. The thickness of the transparent conductive thin film is 20 to 400 nm, preferably 50 to 200 nm, more preferably 80 to 150 nm.
nm. The thicker the thickness, the lower the electric resistance, which is preferable, but cracks and the like are likely to occur during bending. In the case of the vapor deposition method, it is desirable to use an electron beam vapor deposition apparatus capable of vaporizing at a high temperature in consideration of the high melting point of the vapor deposition material.

Regarding the order of forming the thin film, in order to avoid the adverse effect of the plasma generated by the RF power source used during the formation of the transparent inorganic barrier thin film layer on the substrate film and the transparent conductive thin film, the transparent conductive film is formed after the barrier layers are formed on both sides. It is desirable to form a thin film layer. In the production of a transparent inorganic barrier thin film layer, it is preferable to use a vapor deposition method with high productivity and a magnetron sputtering method with high adhesiveness of a thin film in consideration of industrial productivity. At this time, considering the required durability, it is desirable to use the magnetron sputtering method on the side on which the transparent conductive thin film layer is formed and the vapor deposition method on the opposite side.

[0020]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited thereto.
The evaluations in the examples were carried out by the following methods. [Oxygen gas barrier property] US made by Modern Control Co. O
It was measured using X-TRAN100 and displayed in units of cc / m ² / day. [Water vapor barrier property] It was measured according to the moisture permeability test method (cup method) JIS-Z-0208 of the moisture-proof packaging material. [Sheet resistance] The sheet resistance was measured according to the four-probe resistivity measurement method. [Light transmittance] Wavelength 550n with air as reference
The transmittance including the film substrate in m was expressed as a percentage. [Bending Stability] A sample was wound 50 times around a round bar having a diameter of 15 mm, and the ratio of oxygen permeability before and after the winding was determined (R50 / R0). R50 indicates the oxygen permeability after 50 times of winding, and R0 indicates the oxygen permeability before winding.

Example 1 A transparent inorganic barrier thin film was first formed on one surface of a film substrate using a magnetron sputtering device equipped with three 200 × 660 mm targets, using a 100 μm polyarylate transparent film roll as a substrate. ,
Further, a gas barrier thin film and a transparent conductive thin film were sequentially formed on the other surface of the film substrate. SiO _{2 is} used as the target for the transparent inorganic barrier thin film, ITO with a tin oxide ratio of 10% is used as the target for the transparent conductive thin film, and the barrier thin film is 100 sccm of argon flow and 1 sc of oxygen as the sputtering gas.
The total gas pressure is 2.0 mTorr in cm, the transparent conductive thin film has argon 350 sccm, oxygen 3.5 sccm, total gas pressure 5 mTorr, and the power condition is that the barrier thin film has RF 3 kW (2.27).
W / cm ² ), transparent conductive thin film is DC 5.0A, 250V
The film was formed so as to be (0.96 W / cm ² ).
The barrier thin film was treated for 3 minutes to 45 nm, and the transparent conductive thin film was treated for 3 minutes to obtain a transparent conductive film having a thickness of 100 nm. As shown in Table 1, the sheet resistance is 50 Ω / □, the light transmittance is 80%, the oxygen permeability is 0.5 cc / m ² / day, the water vapor permeability is 0.1 g / m ² / day, and the bending stability is 1.1. A good transparent conductive film was obtained.

Example 2 A 100 μm polyarylate transparent film roll was used as a substrate, and a barrier thin film was formed on one side of the film substrate using an electron beam heating type vacuum vapor deposition apparatus. Al ₂ O ₃ was used as the vapor deposition material for the barrier thin film. The degree of vacuum during film formation was 5 × 10 ⁻⁵ Torr, and electron beam irradiation treatment was performed for 20 seconds to obtain a barrier thin film 45 nm. Next, a barrier thin film and a transparent conductive thin film were sequentially formed on the upper surface of the film substrate by using a magnetron sputtering apparatus equipped with three 200 × 600 mm targets on the other surface of the film substrate. The target for the sputter barrier thin film is SiO ₂ , the target for the transparent conductive thin film is ITO with a tin oxide ratio of 10%, the sputtering thin film is an argon flow rate of 100 sccm, the oxygen is 1 sccm, and the total gas pressure is 2.0 mTorr. The transparent conductive thin film is argon. 350scc
m, oxygen 3.5 sccm, total gas pressure 5 mTorr, power conditions, the barrier thin film is RF 3 kW (2.27 W / cm ² ),
Transparent conductive thin film is DC 5.0A, 250V (0.96W
/ Cm ² ). Barrier thin film is processed for 3 minutes, 45 nm, transparent conductive thin film is processed for 3 minutes,
A transparent conductive film having a thickness of 100 nm was obtained. As shown in Table 1, sheet resistance 50Ω / □, light transmittance 80%, oxygen permeability 0.8cc / m ² / day, water vapor permeability 0.2g /
A good transparent conductive film having m ² / day and bending stability of 1.1 was obtained. Furthermore, the barrier thin film formation rate by the vapor deposition method is about 9 times as high as the barrier thin film formation rate by the sputtering method, which shows that there is a very large effect from the viewpoint of productivity.

Comparative Example 1 A transparent conductive film with a barrier thin film was prepared in the same manner as in Example 1 except that the barrier thin film was only on the transparent conductive thin film layer side. As shown in Table 1, since the barrier thin film has one surface, the oxygen permeability is particularly deteriorated, and the bending stability is 2.
A transparent conductive film deteriorated up to 9 times was obtained.

Comparative Example 2 A transparent conductive film with a barrier thin film was prepared in the same manner as in Example 1 except that the barrier thin film was only on the side opposite to the transparent conductive thin film layer. As shown in Table 1, as in Comparative Example 1, a transparent conductive film was obtained in which the oxygen permeability was deteriorated and the bending stability was deteriorated up to 2.7 times.

[0025]

[Table 1]

[0026]

The transparent conductive film of the present invention has high conductivity, good transparency, and excellent oxygen and water vapor barrier properties.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G02F 1/1343 G02F 1/1343 H01B 5/14 H01B 5/14 A 13/00 503 13/00 503B

Claims (8)

[Claims] 1. A transparent inorganic barrier thin film having a thickness of 10 to 100 nm, which is substantially impermeable to oxygen and water vapor, is formed on both surfaces of a transparent film substrate, and further, on one inorganic barrier thin film. 20 transparent conductive thin film on
A transparent conductive film having a thickness of 400 nm. 2. The inorganic barrier thin film has an oxygen permeability of 5 cc.
/ M ² / day or less, the transparent conductive film according to claim 1, wherein water vapor permeability is less than 5 g / m ² / day. 3. The transparent conductive film according to claim 1, wherein the transparent conductive thin film is a metal oxide mainly composed of indium oxide. 4. The inorganic barrier thin film is selected from the group consisting of a metal oxide mainly composed of silicon oxide, a metal oxide mainly composed of aluminum oxide, and a metal nitride mainly composed of silicon nitride. The transparent conductive film according to any one of claims 1 to 3. 5. The sheet resistance value of the transparent conductive thin film is 100.
The transparent conductive film according to claim 1, which has a light transmittance of 70% or more including the transparent film substrate and the inorganic barrier thin film. 6. The transparent conductive film according to claim 1, wherein the transparent film substrate is an aromatic polyester. 7. The transparent conductive film according to claim 1, wherein the transparent film substrate is aromatic polyarylate or polycarbonate. 8. A transparent inorganic barrier thin film having substantially impermeability to oxygen and water vapor is formed on one surface of a transparent film substrate by an electron beam evaporation method, and the barrier is formed on the other surface by a magnetron sputtering method. A method for producing a transparent conductive film, which comprises sequentially forming a thin film and a transparent conductive thin film.