JPWO2012153573A1 - Transparent conductive film, transparent conductive laminate, and touch panel - Google Patents

Abstract

Even when two transparent conductive films are laminated, it is an object to provide a transparent conductive film that can maintain excellent colorless transparency and can easily form a patterned electrode portion. . The transparent conductive film according to the present invention is characterized in that a cerium oxide layer, a transparent low refractive index layer having a refractive index of 1.4 or more and less than 1.7, and a transparent conductive layer are sequentially formed on one surface of a transparent film substrate. . The transparent low refractive index layer is preferably a thin film layer made of silicon oxide, and the transparent conductive layer is preferably a thin film layer made of ITO.

Description

  The present invention relates to a transparent conductive film that can be used as a low-resistance transparent electrode used in a touch panel, and more particularly to a transparent conductive film suitable for use as a capacitive touch panel. The present invention also relates to a transparent conductive laminate comprising the two transparent conductive films, and a touch panel including the transparent conductive film or the transparent conductive laminate.

In recent years, with the expansion of the touch panel market, development of transparent conductive films that can be used as low-resistance transparent electrodes for touch panels has been progressing. For example, in Patent Document 1, on a transparent substrate (1), a resistive film layer (2) made of a transparent conductive metal oxide, a thin film layer (3) made of silicon dioxide, and a resistor made of a transparent conductive metal oxide A film layer (4) is laminated in the order of (1), (2), (3), (4), and describes a resistance film type transparent touch panel electrode member (transparent conductive film) Has been.
Further, as the transparent conductive metal oxide, an indium oxide thin film, a thin film in which tin oxide is doped with indium oxide (ITO thin film), etc. can be used, and the resistive film layer (2) and the resistive film layer (4) It is also described that it is preferable to use the same type of transparent conductive metal oxide.

In addition, as a transparent conductive film suitable for a capacitive touch panel, Patent Document 2,
A transparent conductive film in which a first transparent dielectric layer, a second transparent dielectric layer and a transparent conductive layer are formed in this order on one side or both sides of a transparent film substrate from the transparent film substrate side,
The transparent conductive layer is patterned,
When the refractive index of the first transparent dielectric layer is n1, the refractive index of the second transparent dielectric layer is n2, and the refractive index of the transparent conductive layer is n3, the relationship of n2 <n3 <n1 is satisfied. ,
The thickness of the first transparent dielectric layer is 2 nm or more and less than 10 nm,
The second transparent dielectric layer has a thickness of 20 to 55 nm,
A transparent conductive film having a thickness of 15 to 30 nm is disclosed.
Furthermore, it is preferable that the first transparent dielectric layer is made of a complex oxide containing at least indium oxide and cerium oxide, and that the second transparent dielectric layer is preferably made of SiO ₂ . It is disclosed that indium oxide (ITO) containing tin oxide is preferably used as a constituent material of the transparent conductive layer.

If the electrode member (transparent conductive film) for resistance film type transparent touch panel of Patent Document 1 is used, transparency and pen durability are particularly improved, and a touch panel with higher quality and higher performance can be provided. Has been.
When the transparent conductive film of Patent Document 1 is used as a resistive film type touch panel having a surface resistivity of 200 to 250Ω / □, the thickness of the resistive film layer (transparent conductive layer) is relatively thin. Since there is a spacer between the two transparent conductive films, the yellow color mainly caused by the transparent conductive layer is not a problem. However, in the case of using a transparent conductive laminate in which two transparent conductive films are stacked, such as a capacitive touch panel, there is a problem that yellowishness becomes strong and cannot be practically used.
In particular, as the area of a capacitive touch panel is increasing as in recent years, the response when touching the touch panel with a finger becomes worse. Therefore, for the purpose of preventing deterioration of responsiveness, the surface resistivity is 200Ω / □ or less, preferably 150Ω / □, by increasing the thickness of the transparent conductive layer while maintaining the total light transmittance of the touch panel at 85% or more. Attempts have been made to lower it to the extent that there is a problem that the yellowish color becomes stronger due to the thick transparent conductive layer.

  As shown in FIG. 5A, a conventional transparent conductive film represented by the transparent conductive film described in Patent Document 1 usually has a plurality of transparent layers laminated on a transparent film substrate (1 ′). The surface layer is a transparent conductive layer (4 ′). In addition, the transparent conductive film used in the capacitive touch panel is, as shown in FIG. 5B, by removing at least the transparent conductive layer (4 ′) to form a patterned electrode portion (4′P). It is necessary to form. Here, the pattern-like electrode portion refers to a portion in which the transparent conductive layer, which is the outermost layer of the transparent conductive film, is formed in a desired pattern such as a lattice or checkered pattern. The portion other than the electrode portion is at least a portion (non-electrode portion) where a layer containing a conductive substance such as a transparent conductive layer is not formed.

1 and 2 illustrating the transparent conductive film and the transparent conductive laminate according to the present invention, more specifically, the capacitive touch panel is in the X direction as shown in FIG. 1C. A transparent conductive film (left side) having a patterned electrode part (4Px) electrically connected, and a transparent conductive film (right side) having a pattern electrode part (4Py) electrically connected in the Y direction Are laminated with a transparent adhesive to use as a transparent conductive laminate. In FIG. 1C, the patterned electrode portion (4Px) electrically connected in the X direction and the patterned electrode portion (4Py) electrically connected in the Y direction are represented by different colors. However, as shown in FIG. 2, when a transparent conductive laminate is formed by laminating two transparent conductive films, it is convenient for the purpose of easily grasping the positional relationship between the electrode parts. It is color-coded, and the material itself is the same.
In FIG. 2, A is a plan view of the transparent conductive laminate, B is a sectional view taken along line BB in A, and C is an enlarged view of a portion surrounded by a circle C in A. . As shown in FIG. 2, in the transparent conductive laminate used for the capacitive touch panel, a transparent conductive film having a patterned electrode portion electrically connected in the X direction, and electrically in the Y direction. When the transparent conductive films having the connected patterned electrode portions are stacked, basically, the electrode portions (that is, 4Px and 4Py) formed on each transparent conductive film are laminated so as not to overlap each other. However, in reality, due to the structure of the transparent conductive laminate, there is a slight portion (O) where the electrode parts (4Px and 4Py) formed on the upper transparent conductive film and the lower transparent conductive film overlap each other vertically. End up. For this reason, when the surface of the transparent conductive laminate is viewed from the front, the yellow color of the overlapping portion (O) is conspicuous (see FIG. 2C).
Hereinafter, in the present specification, the portion where the electrode portions overlap is formed on the transparent conductive film of the upper layer and the transparent conductive film of the lower layer in the transparent conductive laminate or the capacitive touch panel using the same as described above. The electrode parts (4Px and 4Py) that are made to overlap each other mean the part where the electrode parts overlap each other. In this specification, yellow means the yellowness of the part where the electrode parts overlap.

Since the touch panel covers the display screen, the touch panel is required to be highly colorless and transparent so that the display screen can be clearly seen.
In order for a touch panel (especially a capacitive touch panel with a large area) to withstand the practical use in terms of yellowness, the b * of the part where the electrodes overlap in the touch panel must be +2.5 or less. It is desirable that +2.0 or less (b * is a value indicating a position between yellow and blue in the CIE L * a * b * color space, and a negative value is blue. Close, positive values indicate yellow.)
In order to achieve this requirement, the material used for each layer constituting the transparent conductive film is basically a colorless and transparent substance, but it also absorbs light of a specific wavelength, so that it becomes yellowish. There's a problem.

The invention of Patent Document 2 provides a transparent conductive film suitable for a capacitive touch panel, and in a transparent conductive film in which a transparent conductive layer is patterned, a pattern portion (electrode portion) and a pattern opening ( The difference from the non-electrode part) is suppressed, and a transparent conductive film having a good appearance can be obtained.In particular, a patterned transparent conductive layer (patterned electrode part), such as a capacitive touch panel, is provided. It is described as being suitable for a touch panel formed on the entire surface of the display unit.
However, even with the transparent conductive film of Patent Document 2, the problem that the yellowness becomes strong when two films are laminated has not been solved.

  Further, the transparent conductive film disclosed in Patent Document 1 and Patent Document 2 are both formed by forming three layers on a film substrate, but according to the configuration disclosed in the examples, Since ITO is contained in both the third layer (the layer closest to the film substrate among the above three layers) and the third layer (outermost layer), only the third ITO layer is removed by etching to form a pattern. Even if this electrode part is formed, there is a problem that electricity is passed through the first layer containing ITO. Therefore, in order to prevent undesired energization, it is necessary to remove all of the first to third layers, and there is a problem that a special etching technique is required and costs are increased.

Japanese Patent No. 4132191 JP 2010-23282

  Therefore, the present invention is not only used when one sheet is used, but also when two sheets are used, particularly when a transparent conductive film is laminated on a glass, like a capacitive touch panel, It is an object of the present invention to provide a transparent conductive film capable of maintaining a b * value of +2.5 or less and capable of easily forming a patterned electrode portion.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a transparent film obtained by sequentially forming a cerium oxide layer, a transparent low refractive index layer, and a transparent conductive layer on one surface of a transparent film substrate. When the conductive film exhibits the desired conductivity, and when two sheets are laminated or when two sheets are further laminated on glass, it was found that a low b * value was maintained, and the present invention was completed. .

  That is, the transparent conductive film according to the present invention is characterized in that a cerium oxide layer, a transparent low refractive index layer having a refractive index of 1.4 or more and less than 1.7, and a transparent conductive layer are sequentially formed on one side of the transparent film substrate. To do.

The transparent low refractive index layer is preferably a thin film layer made of silicon oxide, and the silicon oxide thin film layer is preferably formed by a chemical vapor deposition method (CVD method). .
The transparent conductive layer is preferably a thin film layer made of ITO.

  Moreover, it is preferable that a polyester-type anchor coat layer exists between the said transparent film base material and the said cerium oxide layer.

  The thickness of the cerium oxide layer is preferably 5 to 200 nm, the thickness of the transparent low refractive index layer is preferably 5 to 200 nm, and the thickness of the transparent conductive layer is 10 to 500 nm. It is preferable that

  The transparent conductive film may have a lead-out wiring and / or a patterned electrode part formed thereon. The transparent conductive film on which the lead-out wiring and the patterned electrode portion are formed is suitable for use as a transparent conductive laminate by stacking two sheets and bonding them with a transparent adhesive layer.

  The transparent conductive film is suitable for use in a touch panel, and the transparent conductive laminate is particularly suitable for use in a capacitive touch panel.

  The transparent conductive film of the present invention has appropriate electrical characteristics as a transparent conductive film for a touch panel, and is hardly yellowish when two sheets are stacked. Therefore, the transparent conductive film of the present invention is particularly suitable for use in a capacitive touch panel in which a plurality of transparent conductive films are stacked and used.

FIG. 1 is a diagram schematically showing an example of a transparent conductive film according to the present invention, A is a cross-sectional view of a transparent conductive film, and B is a cross-sectional view of a transparent conductive film in which a patterned electrode portion is formed. , C is a transparent conductive film having a patterned electrode portion electrically connected in the X direction (left side), and a transparent conductive film having a patterned electrode portion electrically connected in the Y direction (right side) FIG. FIG. 2 is a diagram schematically showing a transparent conductive laminate of the present invention formed by bonding two transparent conductive films of FIG. 1 with a transparent adhesive layer, where A is a plan view and B is a diagram in A A sectional view taken along line BB, C is an enlarged view of a portion surrounded by a circle C in A. FIG. FIG. 3 shows the touch panel of the present invention (note that the lead-out wiring is not shown) constructed by bonding the transparent conductive laminate of FIG. 2 and glass with a transparent adhesive layer. FIG. 4 is a diagram schematically showing another example of the transparent conductive film according to the present invention, wherein A is a cross-sectional view of the transparent conductive film, and B is an enlarged view of a portion surrounded by a circle B in A. It is. FIG. 5 is a diagram schematically showing a transparent conductive film (a transparent conductive film containing a conductive substance in the first and third layers) according to the prior art, and A shows a cross-sectional view of the transparent conductive film. B is a view in which only the third layer (outermost layer) is partially removed by etching, and an enlarged view of a portion surrounded by a circle, and arrows in the enlarged view indicate the flow of electricity. C shows a state where a patterned electrode portion is formed by partially removing all of the first to third layers by etching.

As shown in FIG.1A, the transparent conductive film (5) of the present invention has at least a cerium oxide layer (2), a transparent low refractive index layer (3), and a transparent conductive layer on the transparent film substrate (1). (4) has a configuration in which the layers are sequentially stacked. The transparent film substrate (1) and the three layers (2 to 4) have a transparency of a total light transmittance of 80% or more (preferably 85% or more) as a single transparent conductive film. Just do it.
In the transparent conductive film of the present invention, the refractive index means a refractive index with respect to light having a wavelength of 550 nm, and can be measured by spectral reflection spectrum measurement. The thickness of each layer means a physical thickness and can be measured by a fluorescent X-ray analyzer.

  The transparent film substrate (1) used for the transparent conductive film of the present invention can be a transparent plastic film such as a polyethylene terephthalate film, a polyethylene naphthalate film, a polypropylene film, an acrylic film, a polycarbonate film, or a fluorine film. From the viewpoint of properties, a polyethylene terephthalate film is preferable.

Further, as shown in FIG. 4, a transparent hard coat layer (10) made of a resin may be formed on one or both sides of the transparent plastic film (9) (FIG. An example in which a coat layer is formed is shown). Thus, what formed the hard-coat layer in the single side | surface or both surfaces is also contained in the transparent film base material (1) based on this invention.
By forming the hard cord layer on the surface of the transparent plastic film, it is possible to fill the scratches inherent in the transparent plastic film and improve the smoothness and surface strength of the surface of the transparent film substrate on which the hard coat layer is formed. Therefore, it is possible to prevent the transparent film base material from being damaged during post-processing. In particular, when the hard coat layer is formed on the surface of the transparent plastic film on the transparent conductive layer side, in addition to the above points, the conductivity of the transparent conductive film of the present invention can be further stabilized.
The resin used for the hard coat layer is preferably such that the hard coat layer has a pencil hardness of 2H or more, and a transparent resin such as a melamine resin, an ultraviolet curable acrylic resin, or a urethane resin can be used. 1-7 micrometers is preferable.
In addition, interference fringes may occur when the hard coat layer is formed.In this case, an interference prevention layer (thickness) made of resin and high refractive index fine particles is formed between the transparent plastic film and the hard coat layer. It is preferable to provide about 10 to 50 nm, preferably about 20 to 30 nm. As the resin, for example, an acrylic resin, a polyester resin, or the like can be used. As the high refractive index fine particles, for example, fine particles made of titanium oxide, zirconium oxide, or the like can be used.
Thus, what has an interference prevention layer between a transparent plastic film and a hard-coat layer is also contained in the transparent film base material concerning this invention.

The thickness of the transparent film substrate (1) is preferably 10 to 300 μm, more preferably 50 to 260 μm, particularly preferably 50 μm to 200 μm.
If the thickness is less than 10 μm, especially when used for touch panels, the strength of the plastic film is not sufficient when inputting with a finger or pen, etc., so the deformation of the transparent conductive film becomes too large and the transparent conductive layer ( Since cracks occur in 4) and the surface resistivity becomes unstable as a result, it is not preferable. In addition, the transparent conductive film is curled, and as a result, workability is deteriorated in subsequent operations such as incorporating the transparent conductive film into the touch panel.
On the other hand, if the thickness is more than 300μm, when used for a resistive touch panel, when inputting with a finger or pen, it is more than necessary to bring the transparent conductive film into contact with the opposing transparent conductive film. The problem arises that a load must be applied to the. Moreover, since the cost of a transparent conductive film goes up, it is not preferable.

  The cerium oxide layer (2) formed on the transparent conductive film of the present invention is the layer closest to the transparent film substrate (1) among the three layers (2-4). The cerium oxide layer (2) is a transparent high refractive index layer, and its refractive index is about 1.7 to less than 2.5 (more preferably 2.0 to 2.2), and is refracted more than the adjacent transparent low refractive index layer (3). The rate is high. Thus, it is considered that transparency is improved by laminating two layers (2 and 3) having different light refractive indexes. In particular, the difference in refractive index between the cerium oxide layer (2) and the transparent low refractive index layer (3) is preferably 0.2 or more. Furthermore, the use of the cerium oxide layer suppresses the enhancement of yellowness when two transparent conductive films are stacked, compared to the case where a transparent high refractive index layer other than the cerium oxide layer is used. The

The thickness of the cerium oxide layer (2) is preferably 5 nm to 200 nm. If the thickness is less than 5 nm, the characteristics as a transparent high refractive index layer are not sufficiently exhibited, the difference in refractive index from the transparent low refractive index layer (3) becomes small, and the role as a transparent high refractive index layer (transparent This is not preferable because the combination of the low refractive index layer and the transparent layer increases the transparency). On the other hand, if it exceeds 200 nm, it is not preferable because cracks are likely to occur due to film stress.
The thickness of the cerium oxide layer (2) is more preferably 10 nm to 50 nm.

Cerium oxide (cerium oxide) is expressed as CeO ₂ in the theoretical composition formula, and the element ratio of Ce and O is preferably 1: 2 in the present invention. However, the element ratio of Ce and O is not necessarily strictly 1: 2, and the element ratio of Ce and O is slightly larger or smaller (specifically, in the composition formula CeOx, x In the range of 1.6 to 2.1) is also included in the cerium oxide used in the transparent conductive film of the present invention. In the present specification, CeOx (1.6 ≦ x ≦ 2.1) is represented as CeO ₂ as a representative.

The transparent low refractive index layer (3) formed in the transparent conductive film of the present invention is formed between the cerium oxide layer (2) and the transparent conductive layer (4), and the transparency of the transparent conductive film of the present invention It plays a role to improve.
In order to fulfill the above role, the refractive index is preferably 1.4 or more and less than 1.7 (more preferably 1.4 to 1.5), and the thickness is preferably 5 to 200 nm.
If the thickness is less than 5 nm, the characteristics as a transparent low refractive index layer are not sufficiently exhibited, the difference in refractive index from the cerium oxide layer (2) is reduced, and the role as a transparent low refractive index layer (transparent high refractive index layer). This is not preferable because the transparency cannot be sufficiently achieved by the combined use with the refractive index layer.
On the other hand, if it exceeds 200 nm, it is not preferable because cracks are likely to occur due to film stress. A more preferable thickness of the transparent low refractive index layer is 10 nm to 50 nm.

The transparent low refractive index layer (3) is not particularly limited as long as the transparent low refractive index layer (3) satisfies the above refractive index and thickness range, and is an inorganic oxide thin film layer, such as a silicon oxide (SiO ₂ ) thin film layer, An inorganic compound thin film layer such as a magnesium fluoride (MgF ₂ ) thin film layer, a resin thin film layer made of a resin such as a fluorine resin or a silicone resin, or the like can be used.
In particular, the transparent low refractive index layer (3) is preferably a silicon oxide thin film layer from the viewpoint of heat resistance and wet heat resistance.

Silicon oxide (silicon oxide) is expressed as SiO ₂ in the theoretical composition formula, but the element ratio of Si and O is not necessarily strictly 1: 2, and satisfies the above refractive index. In the range, the element ratio of Si and O is somewhat larger or smaller (specifically, in the composition formula SiOx, x is in the range of 1.6 to 2.1), Included in silicon oxide used in film. In this specification, the above SiOx (1.6 ≦ x ≦ 2.1) is represented as SiO ₂ .

  If the transparent low refractive index layer (3) is a layer composed of an electrically insulating substance (such as the above-mentioned inorganic oxide thin film layer, inorganic compound thin film layer, resin thin film layer, etc.), a patterned electrode Since only the transparent conductive layer has to be removed by etching when forming the portion, the time and cost for etching can be reduced. That is, in the transparent conductive film of the present invention, the layer closest to the transparent film substrate (1) is the cerium oxide layer (2) having electrical insulation, so the transparent low refractive index layer (3) is also electrically insulated. If it is made of a material having a property, the transparent conductive layer (4) is the only layer that needs to be patterned. However, the transparent low refractive index layer used in the present invention is not limited to those having electrical insulating properties, and is within the range satisfying the refractive index, polythiophene-based, polyacetylene-based, polyaniline-based, It may be a conductive polymer such as polypyrrole, or a conductive resin thin film layer in which transparent conductive fine particles such as ITO and tin oxide are mixed in a resin. When the transparent low refractive index layer has conductivity, it is necessary to etch away the layer when forming the patterned electrode portion.

The transparent conductive layer (4) formed on the transparent conductive film of the present invention is a layer formed on the outermost layer of the transparent conductive film, and consists of a thin film of a transparent conductive metal oxide. It plays the role which provides electroconductivity.
The transparent conductive metal oxide thin film used for the transparent conductive layer (4) includes indium oxide thin film, tin oxide thin film, zinc oxide thin film, cadmium oxide thin film, thin film in which indium oxide is doped with tin oxide (ITO thin film), etc. A conductive metal oxide thin film conventionally used as a transparent conductive layer of a transparent conductive film can be used.
Among these, an ITO thin film excellent in conductivity is particularly preferable.

The transparent conductive layer (4) plays a role of determining most of the surface resistivity of the transparent conductive film of the present invention, and the surface resistivity is preferably about 5 to 1000Ω / □, preferably 200Ω / □. The following is more preferable.
Further, the thickness of the transparent conductive layer (4) may be a thickness that has the above-mentioned surface resistivity, and is preferably about 10 nm to 500 nm although it depends on the type of the metal oxide thin film layer to be used.
If the thickness is less than 10 nm, the surface resistivity tends to be difficult to stabilize, and the desired conductivity cannot be obtained stably.
On the other hand, if the thickness is greater than 500 nm, the film stress may cause cracks in the transparent conductive layer (4), resulting in poor conductivity.
A more preferable thickness of the transparent conductive layer (4) is 15 nm to 100 nm.

The cerium oxide layer (2), the transparent low-refractive index layer (3), and the transparent conductive layer (4) can be formed by a conventionally known formation method, such as a vacuum evaporation method, a sputtering evaporation method, an electron beam evaporation method, An evaporation method such as a CVD method or a coating method such as a sol-gel method can be used.
In particular, when the transparent low refractive index layer (3) is a silicon oxide layer, the b * value of the portion where the electrode portions overlap each other in the touch panel can be further reduced by forming it by the CVD method.
This is because when the silicon oxide layer is formed by the CVD method, the cerium oxide layer (2) on the silicon oxide layer side is oxidized, so that the degree of oxidation of the cerium oxide layer (2) becomes a transparent film. This is considered to be because the total light transmittance of the cerium oxide layer (2) becomes higher as a result of the higher the silicon oxide layer side than the base material side.

Moreover, in order to use the transparent conductive film of this invention for an electrostatic capacitance type touch panel, you may form leader wiring. The lead-out wiring is a thin line shown as symbol 8 in FIG. 1C, is made of metal, and is usually provided only on the outer peripheral portion of the transparent conductive film. Conventionally, the lead wiring has been mainly formed by patterning the transparent conductive layer and then printing silver paste (screen printing, etc.), but recently, the lead wire (both ends of the transparent conductive film on the left side of FIG. In order to reduce the width of the lead wires (8) bundle existing in the substrate, a method of forming a finer lead wire by etching after forming a thin film of copper or copper alloy on the transparent conductive layer was taken. Yes.
For example, as a method of forming a lead wiring made of copper by etching, a copper layer is laminated on the entire surface by a sputtering vapor deposition method on a transparent conductive layer, and a resist material is applied to the shape of the lead wiring thereon, and then a resist material The copper layer on the portion where the coating is not applied is removed by etching, and only the portion of the copper layer on which the resist material is applied is left, and then the resist material is removed to form copper on the transparent conductive layer. A method of forming a lead wiring is mentioned. The lead wiring generally requires a surface resistance value of about 0.4Ω / □ or less. In order to achieve a surface resistance value of 0.4 Ω / □ or less in the copper lead-out wiring, the copper thickness is preferably set to 100 nm or more.

Further, in order to use the transparent conductive film of the present invention for a capacitive touch panel, at least the transparent conductive layer (4) is formed as a patterned electrode portion electrically connected in the X direction or the Y direction. You may keep it.
Moreover, in order to be usable not only for a touch panel but also for a transparent electrode such as a solar battery or an organic EL, a circuit having at least a transparent conductive layer (4) may be formed.
Examples of methods for forming patterned electrode portions and circuits include etching using chemicals and lasers, and methods using a water-soluble resin layer.

  For example, in the method of forming a patterned electrode portion by etching, a cerium oxide layer (2), a transparent low refractive index layer (3), and a transparent conductive layer (4) are sequentially formed on the entire surface of the transparent film substrate. After forming, on the transparent conductive layer (4), a resist material is applied in the shape of a patterned electrode part, and an etching solution (such as ferric chloride aqueous solution, iodic acid aqueous solution, hydrochloric acid, aqua regia, oxalic acid aqueous solution, etc. For the portion where the resist material is not applied (the portion that becomes the non-electrode portion), only the transparent conductive layer (4) is removed (i.e., the cerium oxide layer (2) and the transparent The refractive index layer (3) is left), and the three layers (2-4) are left on the portion where the resist material is applied (the portion that becomes the electrode portion). Thereafter, by removing the resist material, the cerium oxide layer (2) and the transparent low refractive index layer (3) are formed on the entire surface on the transparent film substrate, and on the transparent conductive layer (4), The transparent conductive film of this invention in which the pattern-shaped electrode part which becomes this can be manufactured.

Incidentally, the transparent conductive film according to the present invention is common with the transparent conductive film described in Patent Document 1 and Patent Document 2 in that it has three layers on the transparent film substrate, but Patent Document 1 and Patent In the transparent conductive film described in the example of Document 2, the layer closest to the film substrate (first layer) contains ITO, which is a conductive substance, and therefore the outermost layer (three layers) of the transparent conductive film. If only the eye (conductive layer) is etched, current is passed through the first layer (see FIG. 5B). Therefore, it is necessary to remove all the layers from the first layer to the third layer (see FIG. 5C), but there is a problem that a special etching technique is necessary and cost is required to remove the first layer. On the other hand, in the transparent conductive film of the present invention, since the first layer is made of cerium oxide having no conductivity, it is not necessary to remove the entire layer by etching, and the formation of a patterned electrode portion by etching is not necessary. It can be performed in a short time and at a low cost. In particular, the second layer of the transparent low refractive index layer (3), be constructed of a material having electrical insulation properties as SiO _2, the third layer transparent conductive layer only (4) only it is removed by etching Therefore, the formation of the patterned electrode portion by etching can be performed in a shorter time and at a lower cost.

  Further, as a method of forming a patterned electrode part using a water-soluble resin layer, for example, on one side of a transparent film substrate, on a part other than the part that forms the electrode part (part that becomes the non-electrode part) A water-soluble resin layer is formed, and then a cerium oxide layer (2), a transparent low refractive index layer (3), and a transparent conductive layer (4) are sequentially formed on the entire surface, and then immersed in water. Then, the three layers (2 to 4) on the water-soluble resin layer and the water-soluble resin layer are removed, and the three layers (2 which are electrode portions) where the water-soluble resin layer is not formed (2 The method of leaving ~ 4) is mentioned. Also by this method, the present invention in which a patterned electrode portion comprising a cerium oxide layer (2), a transparent low refractive index layer (3), and a transparent conductive layer (4) is formed on one side of a transparent film substrate. The transparent conductive film can be manufactured.

  In addition, in the transparent conductive film of the present invention, not only a film in which the above three layers (2 to 4) are laminated on the entire surface on one side of a transparent film substrate, but also a patterned electrode portion is formed as described above. And those in which lead wires are formed.

The transparent conductive film of the present invention in which the lead wiring and the patterned electrode portion are formed is particularly suitable when two sheets are stacked and used as a transparent conductive laminate. Such a transparent conductive laminate includes a non-conductive treatment surface of the upper transparent conductive film (i.e., a surface on the transparent film substrate (1) side) and a conductive treatment surface of the lower transparent conductive film (i.e., the transparent conductive layer). (4) side surface) can be laminated so as to face each other, and can be manufactured by pasting together with a transparent adhesive layer.
As a transparent adhesive used for a transparent adhesive layer, the normal transparent adhesive currently used in order to stick a transparent conductive film in the said field | area can be used. For example, transparent adhesives such as acrylic adhesives and polyether adhesives. The transparent adhesive layer is preferably formed so as to be a uniform layer interposed between two transparent conductive films. To achieve a uniform layer, use a commercially available optically high transparency adhesive (OCA) transfer sheet with a uniform transparent adhesive layer formed between two plastic sheets. It is preferable to transfer the transparent adhesive layer.

  As the touch panel of the present invention, a capacitive touch panel using the transparent conductive laminate is particularly preferable. For example, such a capacitive touch panel described above includes a glass substrate and the transparent conductive laminate. It can be configured by bonding with a transparent adhesive layer, connecting the lead-out wiring and the terminal, and connecting to a touch panel control driver (semiconductor or the like) via a flexible printed wiring.

  The transparent conductive film of the present invention is not only when two sheets are stacked to form a transparent conductive laminate, but also when a transparent conductive laminate is arranged on a glass substrate like an actual capacitive touch panel. However, it is possible to achieve a b * value of +2.5 or less (the lower limit is not particularly limited, but is generally about −3.0). The b * value can be measured with a color difference meter.

As described above, when the transparent conductive film of the present invention is used for a capacitive touch panel, it needs to be bonded to another transparent conductive film or a glass substrate with a transparent adhesive layer. If the adhesion between the transparent film substrate / cerium oxide layer / transparent low refractive index layer / transparent conductive layer constituting the transparent conductive film is low, peeling is likely to occur. There is a problem of becoming.
In particular, when the lead-out wiring is made of copper, the adhesive property with the transparent adhesive is high, and as a result, the transparent conductive film strongly adheres to other members and peels within the transparent conductive film (particularly, the transparent film Peeling between the substrate and the cerium oxide layer is likely to occur.

In order to solve this problem, it is necessary to improve the adhesion between the transparent film substrate and the cerium oxide layer.In the present invention, as shown in FIG. 4, the transparent film substrate (1) and cerium are used. By providing a polyester-based anchor coat layer (11) between the oxide layers (2), the total light transmittance and b * value are maintained in a desired range, while the transparent film substrate and the cerium oxide layer are disposed. It is possible to improve the adhesion.
When the polyester-based anchor coat layer is provided, it is more preferable that the transparent film substrate has a hard coat layer on at least a surface on which the cerium oxide layer is formed. In other words, it is more preferable to form a polyester anchor coat layer on the hard coat layer.

The polyester anchor coat layer can be formed, for example, by curing a hydroxyl group-containing polyester resin with a curing agent that reacts with a hydroxyl group. Examples of the hydroxyl group-containing polyester resin include polyester polyol, and examples of the curing agent include polyisocyanate and / or polyisocyanate prepolymer.
Although the adhesion between the transparent film substrate and the cerium oxide layer is presumed to be reduced by moisture, the polyester-based anchor coat layer formed by curing the polyester polyol and the polyisocyanate and / or polyisocyanate prepolymer, Since it is excellent in water-resistant adhesion, stable adhesion can be achieved without change over time. In addition, because it has excellent heat resistance, it is not easily affected by heat generated in each film forming process (cerium oxide layer, transparent low refractive index layer, transparent conductive layer forming process) performed after the formation of the polyester-based anchor coat layer. (Heat-induced whitening and cracking are unlikely to occur).
Examples of preferred polyisocyanates and / or polyisocyanate prepolymers include IPDI, XDI, and HDI polyisocyanates and / or polyisocyanate prepolymers. By using these, it is possible to form a polyester-based anchor coat layer that does not easily yellow. Here, the IPDI system means isophorone diisocyanate and its modified form, the XDI system means xylylene diisocyanate and its modified form, and the HDI system means hexameletin diisocyanate and its modified form. . Examples of modified forms include trimethylolpropane (TMP) adducts, isocyanurates, burettes, allophanates, and the like.

  The thickness of the polyester anchor coat layer is preferably 5 to 100 nm. If the thickness exceeds 100 nm, the b * value of the transparent conductive film (or transparent conductive laminate or touch panel) may not be maintained in a desired range. On the other hand, when the thickness is less than 5 nm, the adhesion between the transparent film substrate and the cerium oxide layer cannot be sufficiently improved.

  Moreover, the transparent conductive film of this invention can also be used for touch panels other than an electrostatic capacitance type, for example, when setting it as a resistive film type touch panel, the transparent conductive layer formed in the glass surface, and the transparent conductive film of this invention Draw a spacer between the transparent conductive layers of the film facing each other, or between the two transparent conductive films of the present invention so that the transparent conductive layer surfaces face each other, with a dot spacer interposed It can be configured by forming wiring. The transparent conductive film used at this time may be formed with or without a patterned electrode portion.

EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to an Example.
[Example 1] Production of transparent conductive film (transparent film substrate / CeO ₂ layer / SiO ₂ layer (CVD) / ITO layer) On both sides of a 125 μm thick polyethylene terephthalate film (transparent plastic film) by reverse coating method A transparent hard coat layer having a thickness of 2 μm made of an acrylic resin was formed to produce a double-sided hard coat film (transparent film substrate).
Next, a CeO ₂ thin film layer (transparent high refractive index layer, refractive index: 2.1), which is a cerium oxide layer having a thickness of 17 nm, is formed on one side of the double-sided hard coat film by a vacuum deposition method using Ce as a raw material. did.
Next, by using hexamethyldisiloxane as a raw material and oxygen gas as a reaction gas, a 40 nm thick SiO ₂ thin film layer (transparent low refractive index layer, refractive index: 1.5) is formed by chemical vapor deposition (CVD). Formed.
Next, an ITO thin film layer (transparent conductive layer) having a thickness of 30 nm was formed by sputtering vapor deposition using ITO as a raw material to produce the transparent conductive film of the present invention.
Each of the above layers was formed on the entire surface of one side of a transparent film substrate (double-sided hard coat film).

[Example 2] Production of transparent conductive film (transparent film substrate / CeO ₂ layer / SiO ₂ layer (sputter) / ITO layer) Instead of the CVD method of Example 1, Si as a raw material, argon gas as a process gas, Except that a 40 nm thick SiO ₂ thin film layer was formed by sputtering vapor deposition using oxygen gas as the reaction gas, in the same manner as in Example 1, on one side of the transparent film substrate (double-sided hard coat film), The transparent conductive film of the present invention in which a CeO ₂ layer (transparent high refractive index layer, refractive index: 2.1), an SiO ₂ thin film layer (transparent low refractive index layer, refractive index: 1.5), and an ITO layer (transparent conductive layer) are sequentially formed. Manufactured.
The process gas is a gas for generating plasma used for sputtering (striking out the raw material), and the reaction gas is a gas for reacting with the sputtered raw material.

[Comparative Example 1] Production of transparent conductive film (transparent film substrate / ITO layer / SiO ₂ layer (sputter) / ITO layer) Transparent conductive film (single layer) having the same structure as the transparent conductive film disclosed in Patent Document 1 Eyes made ITO layer). Specifically, on one side of a double-sided hard coat film produced in the same manner as in Example 1, an ITO thin film layer having a thickness of 17 nm (transparent high refractive index layer, refractive index: 2.1, using ITO as a raw material) ) Was formed.
Next, a SiO ₂ thin film layer (transparent low refractive index layer, refractive index: 1.5) having a thickness of 40 nm was formed in the same manner as in Example 2. Next, in the same manner as in Example 1, the thickness was 13 nm. The ITO thin film layer (transparent conductive layer) was formed, and the transparent conductive film of Comparative Example 1 was produced.

[Comparative Example 2] Production of transparent conductive film (transparent film substrate / SiOx layer / SiO ₂ layer (sputter) / ITO layer) Instead of CeO ₂ layer in Example 2, Si as a raw material, argon gas as a process gas, Comparative Example 2 was the same as Example 2 except that a 25 nm thick SiOx thin film layer (transparent high refractive index layer, refractive index: 1.75) was formed by sputtering deposition using oxygen gas as the reaction gas. A transparent conductive film was obtained.

[Comparative Example 3] Production of transparent conductive film (transparent film substrate / ZnS layer / SiO ₂ layer (sputter) / ITO layer) Instead of CeO ₂ layer of Example 2, by using vacuum evaporation method using ZnS as a raw material A transparent conductive film of Comparative Example 3 was obtained in the same manner as in Example 2 except that a 36 nm thick ZnS thin film layer (transparent high refractive index layer, refractive index: 2.1) was formed.

[Measurement of physical properties]
The surface resistivity, total light transmittance, and b * value of the transparent conductive films obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were measured. The surface resistivity was measured using Loresta-GP MCP-T600 manufactured by Mitsubishi Chemical Corporation, the total light transmittance was measured using Haze Meter NDH 2000 manufactured by Nippon Denshoku Industries Co., Ltd., and the b * value was Measurement was performed using a SpeCtro Color Meter SQ2000 manufactured by Nippon Denshoku Industries Co., Ltd.
Furthermore, in order to investigate whether or not the adhesion between each layer formed on the transparent conductive film is practically problematic, the tape adhesion was examined by the following method. First, after the cellophane tape is adhered to the transparent conductive layer (ITO layer), the cellophane tape is peeled off and confirmed, and any layer of the transparent high refractive index layer, the transparent low refractive index layer, and the transparent conductive layer is checked from the transparent conductive film. Also, the case where no peeling occurred was evaluated as ◯, and the case where any of the transparent high refractive index layer, the transparent low refractive index layer and the transparent conductive layer was peeled off from the transparent conductive film was evaluated as x.

Moreover, when actually manufacturing the transparent conductive laminate and the touch panel using the transparent conductive films obtained in Examples 1 and 2 and Comparative Examples 1 to 3, the b * value of the portion where the electrode portions overlap each other In order to grasp the value of the total light transmittance, the laminated body in which the electrode portions overlap each other (that is, a laminate of two transparent conductive films that do not form a patterned electrode portion), and the laminated body A panel having the same was manufactured, and b * value and total light transmittance were measured.
First, for each of the transparent conductive films obtained in Examples 1 and 2 and Comparative Examples 1 to 3, a laminate was produced by laminating two transparent conductive films with a transparent adhesive layer. The transparent adhesive layer uses a highly transparent adhesive transfer tape (product number: 8146-4 manufactured by Sumitomo 3M Limited) in which a uniform acrylic transparent adhesive layer is formed between two plastic sheets. It formed by transferring to a transparent conductive film. This laminate is bonded so that the non-conductive treatment surface (transparent film substrate side surface) of the upper transparent conductive film faces the conductive treatment surface (ITO layer side surface) of the lower transparent conductive film. It has been.
The total light transmittance and b * value were measured in the same manner as described above for the laminate composed of the two transparent conductive films thus obtained.

In addition, a panel having a structure in which the laminate was laminated on a colorless and transparent plate-like glass having a thickness of 2 mm was formed. The glass and the laminate were bonded together using the acrylic transparent adhesive layer. The panel made of the laminate and glass thus obtained was measured for the total light transmittance and b * value in the same manner as described above. Table 1 shows the measurement results.
The laminate and the panel are the transparent conductive laminate shown in FIG. 2B, except that the patterned electrode portion made of the transparent conductive layer is not formed (the transparent conductive layer is formed on the entire surface). And it has the same structure as the touch panel shown in FIG.

As can be seen from Table 1, the transparent conductive films of Examples 1 and 2 and Comparative Examples 1 to 3 each had a b * value of +2.5 or less.
However, when a laminate was formed by stacking two sheets, the transparent conductive films of Comparative Example 1 and Comparative Example 2 had a b * value exceeding +2.5. The transparent conductive film of Comparative Example 3 was able to achieve a b * value of +2.5 or less, but had poor tape adhesion and could not withstand practical use.
Furthermore, when a panel made of two transparent conductive films laminated on glass is used, the b * value of the panel using the transparent conductive films of Comparative Examples 1 to 3 greatly exceeds +2.5, and it is strongly yellowish. It was.

On the other hand, the transparent conductive film of the present invention of Example 1 and Example 2 is a case where a panel is formed by laminating two transparent conductive films on glass even when a laminate is formed by stacking two sheets. In addition, the b * value +2.5 or less could be maintained, and the desired colorless transparency could be realized.
In addition, when the transparent conductive film is in the form of a touch panel, it is preferable to achieve a total light transmittance of 85% or more, but both panels using the transparent conductive film of Example 1 and Example 2 This criterion was met. In contrast, the total light transmittance of the panel using the transparent conductive film of Comparative Example 3 did not reach 85%.

Further, Table 1 shows a comparison between Example 1 in which the second layer (transparent low refractive index layer) SiO ₂ layer was formed by the CVD method and the transparent conductive film in Example 2 formed by the sputtering vapor deposition method. As described above, in the case of the transparent conductive film or laminate, the b * value was smaller in Example 2, but in the case of the panel, the b * value was smaller in Example 1, and the phenomenon of reversal was observed. . In addition, the total light transmittance was higher in Example 1 than in Example 2 in any of the transparent conductive film, the laminate, and the panel. It performed several times additional test for this has been compared SiO ₂ layer formed by the SiO ₂ layer and the sputtering deposition method was formed by a CVD method, similarly to the above embodiments, is better to form the SiO ₂ layer by the CVD method, the panel As a result, the total light transmittance was high and the b * value was low. From these results, it was found that the transparent conductive film in which the SiO ₂ layer (transparent low refractive index layer) was formed by the CVD method was more suitable for a capacitive touch panel.
When differences in the method of forming the SiO ₂ layer is to consider the causes that affect the total light transmittance and b * value, it is better to form the SiO ₂ layer by CVD than sputtering deposition method, an SiO ₂ layer of CeO ₂ layer oxidation degree side surface is oxidized is increased, as a result, the CeO ₂ oxide layer, oxidation degree of the inclination occurs (CeO ₂ layer of oxidation degree is higher in the SiO ₂ layer side of the transparent film substrate side ), Which is considered to contribute to the improvement of the total light transmittance and the b * value.

[Formation of patterned electrode by etching]
About the transparent conductive film manufactured in Example 1 and Comparative Example 1, patterned electrode portions electrically connected in the X or Y direction were formed by an etching method.

[Example 3]
First, on the transparent conductive film of the present invention (transparent film substrate / CeO ₂ layer / SiO ₂ layer (CVD) / ITO layer) produced in Example 1, a resist material (Ares SPR manufactured by Kansai Paint Co., Ltd.) is patterned. of was applied to the shape of the electrode portion, using 2% aqueous hydrochloric acid solution as an etching solution, wet etching treatment for 70 seconds at 40 ° C., the portion where the resist material is not applied is CeO ₂ by removing only ITO layer Layer / SiO ₂ layer was left, and CeO ₂ layer / SiO ₂ layer / ITO layer was left in the portion where the resist material was applied. Thereafter, the resist material is removed with a 2% aqueous sodium hydroxide solution to form a CeO ₂ layer / SiO ₂ layer on the entire surface of the transparent film substrate, and ITO electrically connected in the X direction thereon. The transparent conductive film of this invention in which the pattern-shaped electrode part which consists of layers was formed was manufactured.
The portions other than the patterned electrode portions are non-electrode portions composed of a CeO ₂ layer / SiO ₂ layer.
The transparent conductive film of Example 1 has the desired properties by etching and removing only the third (outermost layer) ITO layer because the CeO ₂ layer and the SiO ₂ layer are both insulating. A transparent conductive film having a patterned electrode portion was obtained.
Further, in the same manner as described above, a transparent conductive film of the present invention in which a patterned electrode portion electrically connected in the Y direction was formed was also produced.

[Comparative Example 4]
In place of the transparent conductive film of the present invention produced in Example 1, the transparent conductive film produced in Comparative Example 1 (transparent film substrate / ITO layer / SiO ₂ layer / ITO layer) was used except that In the same manner as in Example 3, a transparent conductive film of Comparative Example 4 in which a patterned electrode portion composed of ITO layer / SiO ₂ layer / ITO layer electrically connected in the X direction was formed was produced.
The portions other than the patterned electrode portions are non-electrode portions where no ITO layer / SiO ₂ layer / ITO layer remains (see FIG. 5C).
Further, in the same manner as described above, a transparent conductive film of Comparative Example 4 in which a patterned electrode portion electrically connected in the Y direction was formed was also produced.
When etching the transparent conductive film produced in Comparative Example 1, only the third (outermost layer) ITO layer was removed by etching, and there was a problem that electricity would be passed through the first ITO layer. (See arrows in the partially enlarged view of FIG. 5B). For this reason, in order to obtain a transparent conductive film in which a patterned electrode portion having desired characteristics is formed, it is necessary to etch and remove all layers from the first layer to the third layer. However, since the second SiO ₂ layer is difficult to remove by etching, it is necessary to use a special etching method such as laser etching to remove the first layer, and only the third layer is removed by etching. Compared to the case, more cost and time were required.

  From the above results, it was proved that the transparent conductive film of the present invention has an advantage that a patterned electrode portion can be formed by etching in a short time and at low cost.

[Production of transparent conductive laminate]
[Example 4]
The transparent conductive film of the present invention in which a patterned electrode portion electrically connected in the X direction, which was manufactured in Example 3, was formed, and a patterned electrode portion electrically connected in the Y direction was formed. The transparent conductive film of the present invention was produced by bonding the transparent conductive film of the present invention to the transparent adhesive layer formed using the highly transparent pressure-sensitive adhesive transfer tape (see FIG. 2). ). Although it laminated | stacked so that the electrode parts formed in each transparent conductive film might not overlap as much as possible, the part which electrode parts slightly overlapped on the structure of the transparent conductive laminated body arose. As shown in FIG.2B, this transparent conductive laminate is composed of a non-conductive treatment surface (surface on the transparent film substrate (1) side) of the upper transparent conductive film and a conductive treatment surface (ITO) of the lower transparent conductive film. The layers (4) side) are bonded so that they face each other.

[Comparative Example 5]
Instead of using the transparent conductive film in which the patterned electrode portion manufactured in Comparative Example 4 was used instead of the transparent conductive film of the present invention in which the patterned electrode portion manufactured in Example 3 was formed, In the same manner as in Example 4, a transparent conductive laminate of Comparative Example 5 was produced.

When the transparent conductive laminate of the present invention produced in Example 4 and the transparent conductive laminate produced in Comparative Example 5 were compared visually, the transparent conductive laminate produced in Comparative Example 5 was overlapped with each other. It was clearly confirmed that the portion was yellowish.
On the other hand, in the transparent conductive laminate of the present invention produced in Example 4, the yellowness of the portion where the electrode portions overlap each other was hardly felt visually, and the existence thereof was not known at all.

[Manufacture of capacitive touch panel]
[Example 5]
A transparent transparent plate formed by transferring the colorless transparent plate-like glass having a thickness of 2 mm and the transparent conductive layer surface (conductive treatment surface) of the transparent conductive laminate of the present invention using the highly transparent adhesive transfer tape. While sticking together with an adhesive layer, the lead-out wiring and the terminal were connected, and the touch panel control driver was connected through the flexible printed wiring, and the capacitive touch panel of the present invention was manufactured. The transparent conductive laminate has the same configuration as the transparent conductive laminate produced in Example 4 except that lead wires are formed on each transparent conductive film.
The lead wiring was formed of Ag or Cu.
When forming the lead wiring made of Ag, the same process as in Example 3 was performed to produce a transparent conductive film on which the patterned electrode portion made of the ITO layer was formed, and then a screen printing method using an Ag paste. Formed by.
When forming a lead wire made of Cu, a 120 nm thick Cu layer is laminated on the entire surface of the ITO layer by sputtering deposition, and then a resist material (Ares SPR made by Kansai Paint Co., Ltd.) is formed on top of it. By applying a 5% copper chloride aqueous solution as an etching solution for Cu and performing a wet etching process at 40 ° C. for 60 seconds, only the Cu layer where the resist material is not applied is removed, and the resist material is For the applied part, the Cu layer was left. Thereafter, the resist material was removed with a 2% aqueous sodium hydroxide solution to produce a lead wiring made of Cu on the ITO layer. After forming the lead-out wiring, the same treatment as in Example 3 was performed to manufacture a transparent conductive film on which a patterned electrode portion made of an ITO layer was formed.

[Comparative Example 6]
Instead of the transparent conductive laminate of the present invention, a transparent conductive laminate of a comparative example (having the same configuration as the transparent conductive laminate produced in Comparative Example 5 except that the lead-out wiring described above is formed). A capacitive touch panel of Comparative Example 6 was produced in the same manner as Example 5 except that it was used.

When comparing the capacitance type touch panel of the present invention manufactured in Example 5 and the capacitance type touch panel manufactured in Comparative Example 6 with the naked eye, the capacitance type touch panel manufactured in Comparative Example 6 is It was clearly confirmed that the portion where the electrode portions overlap each other is yellowish.
On the other hand, in the capacitive touch panel of the present invention produced in Example 5, the yellowness of the portion where the electrode portions overlap each other was hardly felt visually, and the existence thereof was not known at all.

[Examination on Adhesion of Transparent Film Base / CeO ₂ Layer]
When a capacitive touch panel is manufactured, if the lead wiring is made of Ag, delamination (transparent film substrate / CeO ₂ layer / transparent low refractive index layer / transparent conductive layer) is a practical problem for the transparent conductive film. No peeling between the transparent film substrate and the CeO ₂ layer was observed when the lead wiring was made of Cu. This is because the lead wire made of Cu has higher adhesion to the transparent adhesive than the lead wire made of Ag, so the surface of the transparent conductive film is stronger than other members (another transparent conductive film or glass). As a result, it is considered that peeling is likely to occur between the transparent film substrate having the lowest adhesion (adhesion) in the transparent conductive film and the CeO ₂ layer.

To improve the adhesion between the transparent film substrate and the CeO ₂ layer, we first considered modifying the surface of the transparent film substrate (introducing hydroxyl groups) by corona discharge, ion beam irradiation, and plasma treatment. Even when this surface processing method was used, the adhesiveness between the transparent film substrate and the CeO ₂ layer was lowered as compared with the case where the surface processing was not performed.
The adhesion between the transparent film substrate and the CeO ₂ layer deteriorated due to the introduction of a hydroxyl group, and when the transparent conductive film was heat-treated (140 ° C., 10 minutes), a tendency to improve the adhesion was observed. Therefore, it is considered that the adhesion between the transparent film substrate and the CeO ₂ layer is lowered by moisture.

Next, an anchor coat layer was provided on the transparent film substrate to investigate the adhesion between the transparent film substrate and the CeO ₂ layer. The results are shown in Table 2.
The transparent film substrate used in Example 6-1 and Example 6-2 has a transparent hard coat layer having a thickness of 2 μm made of an acrylic resin on both sides of a polyethylene terephthalate film having a thickness of 125 μm by a reverse coating method. Formed. Thereafter, a polyester anchor coat layer having a thickness of 20 nm was formed only on the transparent film substrate of Example 6-2 by the gravure method (one side only).
The transparent film base material used in Example 6-3 and Example 6-4 has a 2 μm thick transparent hard coat layer made of urethane resin by reverse coating on both sides of a 125 μm thick polyethylene terephthalate film. Formed. Thereafter, a polyester anchor coat layer having a thickness of 20 nm was formed only on the transparent film substrate of Example 6-4 by the gravure method (one side only).

  The above-mentioned polyester-based anchor coat layer uses VM Anchor P331S of Toyo Ink Co., Ltd. (containing polyester polyol and nitrocellulose in a 1: 1 weight ratio in the solvent) as the main agent, and Mitsui Chemicals, Inc. as the curing agent Using the company's Takenate D-140N (including IPDI polyisocyanate prepolymer [adduct of IPDI and TMP] in the solvent) so that the solid content ratio of the main agent and curing agent is 1: 1.33 And the mixture was cured.

For each transparent film substrate of Examples 6-1 to 6-4, a CeO ₂ thin film layer, a SiO ₂ thin film layer, an ITO thin film layer are formed in the same manner as in Example 1, and the transparent conductive film of the present invention is formed. did.
Then, about each transparent film, the external appearance evaluation was performed visually and the thing which cannot be used practically by generation | occurrence | production of whitening and a crack was set to x, and others were set to (circle).
Further, the surface resistivity, tape adhesion, total light transmittance, and b ^* value were measured for each transparent film by the same method as in paragraph [0054].
Further, by the same method as in paragraphs [0055] and [0056], a laminate composed of two transparent conductive films and a panel composed of the laminate and glass were produced, and the total light transmittance and b * value were determined. It was measured.

Furthermore, in order to examine the degree of delamination in the transparent conductive film when the lead wiring made of Cu was formed, a 120 nm thick Cu layer was formed on the surface of the ITO layer side of each transparent conductive film by sputtering vapor deposition. Was laminated on the entire surface, and adhesion (adhesion) was evaluated by a cross-cut method in accordance with JIS K5600-5-6 (ISO 2409). In JIS K5600-5-6, the test is conducted at 25 masses. In this test, in order to examine the adhesion in more detail, the test was conducted at 100 masses, and the Cu layer, ITO layer, SiO ₂ layer were tested. In addition, 90 or more of 100 portions where no CeO ₂ layer was peeled were evaluated as ◎, 60 or more as ○, 30 or more as Δ, and less than 30 as ×. The evaluation ○ or higher is at a level where there is no practical problem.

The results are shown in Table 2.

As shown in Table 2, when a polyester-based anchor coat layer was provided (Examples 6-2 and 6-4), compared to a case where no anchor coat layer was provided (Examples 6-1 and 6-3), Cross-cut adhesion improved. In addition, the transparent conductive film, the laminate, and the panel all had a total light transmittance of 85% or more and a b * value of +2.5 or less.
In contrast, when the anchor coat layer made of epoxy resin was provided, the total light transmittance and b * value tended to deteriorate compared to the case where the anchor coat layer was not provided. There was a tendency for adhesion and cross-cut adhesion to deteriorate.

The transparent conductive film of the present invention is not yellowish even when it is used in a stack of two sheets, so even when two transparent conductive films are stacked and used like a capacitive touch panel, display The screen can be clearly seen, which is very useful.
In addition, since it is easy to form a patterned electrode portion by etching, the patterned electrode portion can be formed at low cost and in a short time.

1, 1 'transparent film substrate
2 Cerium oxide layer
2 'Transparent high refractive index layer containing conductive material
3, 3 'transparent low refractive index layer
4, 4 'transparent conductive layer
4P, 4'P Transparent electrode layer pattern electrode
4Px Patterned electrode part consisting of a transparent conductive layer and electrically connected in the X direction
4Py Patterned electrode part made of a transparent conductive layer and electrically connected in the Y direction
5, 5 'transparent conductive film
6 Transparent adhesive layer
7 Glass
8 Lead wiring
9 Transparent plastic film
10 Hard coat layer
11 Polyester anchor coat layer

Claims (10)

  A transparent conductive film, wherein a cerium oxide layer, a transparent low refractive index layer having a refractive index of 1.4 or more and less than 1.7, and a transparent conductive layer are sequentially formed on one surface of a transparent film substrate.   2. The transparent conductive film according to claim 1, wherein the transparent low refractive index layer is a thin film layer made of silicon oxide.   The transparent conductive film according to claim 1 or 2, wherein a polyester-based anchor coat layer is present between the transparent film substrate and the cerium oxide layer.   The transparent conductive film according to claim 2 or 3, wherein the silicon oxide thin film layer is formed by a chemical vapor deposition method (CVD method).   The transparent conductive film of any one of Claims 1-4 whose said transparent conductive layer is a thin film layer which consists of ITO.   The thickness of the cerium oxide layer is 5 to 200 nm, the thickness of the transparent low refractive index layer is 5 to 200 nm, and the thickness of the transparent conductive layer is 10 to 500 nm. The transparent conductive film of any one of these.   The transparent conductive film of any one of Claims 1-6 in which the extraction wiring and / or the electrode part of pattern shape are formed.   The transparent conductive laminated body formed by laminating | stacking two transparent conductive films of any one of Claims 1-6 in which the lead-out wiring and the pattern-like electrode part are formed, and bonding together with a transparent adhesive layer.   The touch panel provided with the transparent conductive film of any one of Claims 1-7.   A capacitive touch panel comprising the transparent conductive laminate according to claim 8.