JP6789168B2 - Transparent conductive film and touch panel using it - Google Patents

Description

The present invention relates to a transparent conductive film having a second cured resin layer, a transparent resin film, a first cured resin layer, and a transparent conductive layer in this order, and a touch panel using the same.

Conventionally, so-called conductive glass in which an indium oxide thin film is formed on glass is well known as a transparent conductive member. However, since the base material of conductive glass is glass, it is inferior in flexibility and processability, and it may be difficult to apply it depending on the application. Therefore, in recent years, transparent conductive films using a plastic film base material such as polyethylene terephthalate have become widespread because of their advantages such as excellent impact resistance and light weight in addition to flexibility and workability.

However, as displays with a transparent touch panel mounted on the liquid crystal display element have become widespread from mobile size to medium to large size, not only the characteristics of the liquid crystal display element have become more sophisticated, but also the transparent conductive film for the touch panel. There is also an increasing demand for improvement of the optical characteristics of the film, and in particular, the transparent conductive film using conventional polyethylene terephthalate has a phase difference of several thousand nm depending on the thickness, so that it may not be used under a polarizing plate. is there.

Therefore, as a base material for a transparent conductive film in which the phase difference is controlled, for example, a cycloolefin-based resin film, a polycarbonate-based resin film, and the like have been proposed (for example, Patent Document 1). However, a base material such as a cycloolefin resin film is soft, and it has been proposed to form a cured resin layer (hard coat layer) on both sides of the base material and carry it by a roll-to-roll method (for example, Patent Document 2). ).

On the other hand, when a transparent conductive layer such as an ITO (indium tin oxide composite oxide) film is formed on a plastic film base material by a roll-to-roll method, it is sputtered at a high temperature due to restrictions due to the heat resistance of the base material. The membrane cannot be made. Therefore, the ITO immediately after the film formation is an amorphous film (a part of the ITO film may be crystallized depending on the film formation temperature). Such an amorphous ITO film has problems such as strong yellowing, poor transparency, and a large change in resistance. Therefore, in general, it is possible to convert an amorphous ITO film into a crystalline ITO film by forming an amorphous ITO film and then heat-treating it in an oxygen atmosphere in the atmosphere by a roll-to-roll manufacturing method. (Crystallization and annealing treatment).

JP-A-2010-162746 Japanese Unexamined Patent Publication No. 2016-081733

However, there are cases where the transparent conductive layer is crystallized and annealed immediately after the film is formed (the former), but due to manufacturing reasons, the transparent conductive layer is not subjected to the crystallization annealing immediately after the film formation and is used in a roll state. In some cases, after storing until, crystallization annealing treatment is performed when necessary (the latter). According to the studies by the present inventors, in the former case (that is, when the amorphous film is crystallized and annealed), no particular problem occurs, but in the latter case (that is, a part of the amorphous film is naturally crystallized by storage). When the transparent conductive layer was crystallized and annealed), it was found that cracks were generated in the transparent conductive layer. In particular, it has been found that when a relatively soft cured resin layer is formed on a substrate having a high coefficient of linear expansion, the above-mentioned crack problem occurs. However, if only a cured resin layer having the same hardness is provided on both sides of the base material to increase the hardness, the film will be formed due to the heat and transfer tension applied in the roll-to-roll transfer process such as the film forming process and the crystallization annealing process. It turned out that it may be easily cracked.

Therefore, an object of the present invention is a case where a substrate having a high linear expansion coefficient is used, and the transparent conductive layer is subjected to crystallization annealing after storage without crystallization annealing immediately after film formation. Even if there is, it is an object of the present invention to provide a transparent conductive film capable of suppressing cracking in the transparent conductive layer and suppressing breakage of the transparent resin film in the roll-to-roll transfer step, and a touch panel using the transparent conductive film.

As a result of diligent studies to solve the problem of preventing cracks, the present inventors first, as a result, the transparent conductive layer partially crystallized naturally has less flexibility than the amorphous film, and is subjected to crystallization annealing treatment. At times, it was not possible to keep up with the thermal expansion of the base material, and I thought that cracks might occur in the transparent conductive layer. In other words, the transparent conductive layer of the amorphous film can follow the thermal deformation of the base material and the cured resin layer during the crystallization annealing treatment, whereas it is partially crystallized and transparent. It was thought that the conductive layer was hard and could not follow the thermal deformation of the base material and the cured resin layer, and cracks were likely to occur on the surface of the transparent conductive layer. Therefore, even if a base material having a high coefficient of linear expansion of the transparent resin film is used, and even if the transparent conductive layer is partially crystallized, the hard first cured resin layer that suppresses thermal deformation is made inorganic. It has been found that the problem of preventing the occurrence of cracks can be solved by the composition by containing a predetermined amount of particles.

Furthermore, as a result of diligent studies to solve the problem of suppressing film breakage while solving the problem of preventing cracks, the present inventors have applied to each cured resin layer formed on both sides of the transparent resin film. It was considered that it is not enough to achieve both of the above problems if the hardness is the same on both sides. Therefore, it was thought that the above problems could be achieved by adjusting the hardness of each cured resin layer on one side in a well-balanced manner. That is, the cured resin layer (first cured resin layer) on the surface side on which the transparent conductive layer is formed contains a predetermined amount of inorganic particles to increase the hardness, which is a characteristic contrary to the flexibility, while increasing the hardness. It was considered that the occurrence of cracks could be prevented by controlling separately from the cured resin layer (second cured resin layer). On the other hand, the second cured resin layer is provided with flexibility, which is a characteristic contrary to the increase in hardness, to improve bending resistance and to be a transparent resin in a transport process such as a film forming process. We thought that it would be possible to prevent the film from breaking. By adjusting the hardness of each cured resin layer on one side in a well-balanced manner in this way, it has been found that the above object can be achieved while achieving both, and the present invention has been completed.

That is, the present invention is a transparent conductive film having a second cured resin layer, a transparent resin film, a first cured resin layer, and a transparent conductive layer in this order, and the transparent resin film is a wire. The expansion coefficient is 5.0 × 10 ^-5 cm / cm · ° C. or more, the hardness of the first cured resin layer by the indentation test is 0.27 GPa or more, and the indentation test of the second cured resin layer is performed. The hardness of the first cured resin layer is less than 0.29 GPa, and the first cured resin layer is a transparent conductive film containing 10 to 70% by weight of inorganic particles. The various physical property values in the present invention are values measured by the method adopted in Examples and the like unless otherwise specified.

As a result, even when a base material having a high coefficient of linear expansion is used, and even when the transparent conductive layer is not crystallized and annealed immediately after film formation but is stored and then crystallized and annealed, it is transparent. Cracks do not occur in the conductive layer, and breakage of the transparent resin film in the roll-to-roll transfer process can be suppressed.

The refractive index of the first cured resin layer in the present invention is preferably 1.45 to 1.50.

In the present invention, it is preferable that the hardness of the first cured resin layer in the indentation test is 0.29 GPa or more, and the hardness of the second cured resin layer in the indentation test is less than 0.29 GPa. As a result, since each cured resin layer has the hardness in the above range, the balance can be adjusted, so that the line running performance at the time of film formation of the transparent conductive layer can be improved, and the handleability in the annealing step and the post-process is improved. This makes processing and transportation easier, and work efficiency can be improved. In addition, it is advantageous in achieving both the problem of preventing crack generation and the problem of suppressing film breakage.

In the present invention, it is preferable that the amount of plastic deformation by the indentation test of the first cured resin layer is 50 nm or less, and the amount of plastic deformation by the indentation test of the second cured resin layer is larger than 50 nm. As a result, the first cured resin layer can be formed harder, and the transparent resin film can be conveyed while being prevented from being thermally deformed due to thermal expansion or the like. Therefore, there are problems of preventing cracks and suppressing film breakage. It is more advantageous to achieve both.

In the present invention, the value obtained by subtracting the hardness of the second cured resin layer by the indentation test from the hardness of the first cured resin layer in the indentation test is preferably greater than 0 GPa and 1.0 GPa or less. Having such a hardness difference is more advantageous in realizing both the above-mentioned effects and effects.

In the present invention, it is preferable to further provide one or more optical adjustment layers between the first cured resin layer and the transparent conductive layer. Since the refractive index can be controlled by the optical adjustment layer, when the transparent conductive layer is patterned, the difference in reflectance between the pattern forming portion and the pattern opening can be reduced, and the transparent conductive layer pattern is difficult to see. Visibility can be improved in a display device such as a touch panel.

The transparent resin film in the present invention is preferably a cycloolefin resin film or a polycarbonate resin film. Since the cycloolefin-based resin film or the polycarbonate-based resin film is generally a base material having a low retardation, it can be used even under a polarizing plate, and its use as a transparent conductive film is greatly expanded. Can be done.

The inorganic particles in the present invention are preferably silica particles. By using silica particles, the transparency is high and the resin can be uniformly dispersed, and the first cured resin layer can be formed harder, so that thermal deformation due to thermal expansion of the transparent resin film can be prevented. Therefore, it is more advantageous to achieve both the problem of preventing crack generation and the problem of suppressing film breakage.

The transparent conductive film of the present invention is preferably used for an inner touch panel. By using the transparent conductive film of the present invention for the inner touch panel that is laminated under the polarizing plate of the liquid crystal display element, the influence of the optical characteristics is less than that of the outer type that is laminated on the polarizing plate of the liquid crystal display element. , It is more advantageous in terms of the pattern appearance of the transparent conductive layer.

The touch panel of the present invention preferably contains the transparent conductive film. By using the transparent conductive film, even when a substrate having a high linear expansion coefficient is used, the transparent conductive layer is crystallized and annealed after storage without being crystallized and annealed immediately after film formation. Even in this case, it is possible to prevent cracks from occurring in the transparent conductive layer, and it is possible to improve the quality of the touch panel. In addition, the line running performance at the time of film formation of the transparent conductive layer can be improved, and the breakage of the transparent resin film in the roll-to-roll transfer process can be suppressed, so that the handleability in the annealing process and the post-process can be improved, and the processing transfer can be performed. Is easy and work efficiency can be improved.

It is a schematic sectional view of the transparent conductive film which concerns on one Embodiment of this invention. It is a schematic sectional view of the transparent conductive film which concerns on other embodiment of this invention. It is a schematic side view for demonstrating the procedure of a 180 ° bending test. It is a photograph of a laser microscope (× 50 times) after a crack confirmation test in Comparative Example 1. It is a photograph of the non-contact three-dimensional surface measurement after the crack confirmation test in Comparative Example 1. It is a photograph of a laser microscope (× 50 times) after a crack confirmation test in Example 1.

An embodiment of the transparent conductive film of the present invention will be described below with reference to the drawings. However, in some or all of the figures, parts unnecessary for explanation are omitted, and some parts are enlarged or reduced for ease of explanation. The terms indicating the positional relationship such as top and bottom are used merely for the sake of facilitation of explanation, and there is no intention of limiting the configuration of the present invention.

<Transparent conductive film>
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing an embodiment of the transparent conductive film of the present invention. The transparent conductive film 10 has a second cured resin layer 2', a transparent resin film 1, a first cured resin layer 2, and a transparent conductive layer 3 in this order. The first cured resin layer 2 is formed on the first main surface S1 side of the transparent resin film 1, and the second cured resin layer 2'is on the side opposite to the first main surface S1 of the transparent resin film 1. It is formed on the second main surface S2 side. That is, the first cured resin layer 2 and the second cured resin layer 2'are formed on both sides of the transparent resin film 1. The first cured resin layer 2 and the second cured resin layer 2'include those that function as an anti-blocking layer and a hard coat layer. Although not shown in FIG. 1, one layer or two or more transparent conductive layers are provided on the side of the second cured resin layer 2 ′ opposite to the surface on the transparent resin film 1 side, if necessary. be able to.

In the transparent conductive film 11 shown in FIG. 2, in addition to the layer structure of the transparent conductive film 10 shown in FIG. 1, one optical adjusting layer 4 is provided between the first cured resin layer 2 and the transparent conductive layer 3. It is also provided. The one-layer optical adjustment layer 4 may be two or more optical adjustment layers 4. Although not shown in FIG. 2, if necessary, one layer or two or more optical adjustment layers are provided on the side of the second cured resin layer 2 ′ opposite to the surface on the transparent resin film 1 side. Can be done. A transparent conductive layer can be further provided on the optical adjustment layer.

Although not shown in FIGS. 1 and 2, a carrier film having an adhesive layer on one surface side of the protective film is transparently conductive via the adhesive layer from the viewpoint of facilitating roll-to-roll transfer. The films 10 and 11 can be laminated. In this case, the surface side of the transparent conductive films 10 and 11 on which the second cured resin layer 2'is formed can be bonded to the pressure-sensitive adhesive layer to form a transparent conductive film laminate.

(Transparent resin film)
As the transparent resin film, one used as a base material of the transparent conductive film can be used. When the coefficient of linear expansion of the transparent resin film is 5.0 × 10 ⁻⁵ cm / cm · ° C. or higher, the transparent conductive film formed on the resin film tends to have cracks, and the present invention has a tendency to cause the cracks. The effect will be noticeable. If the linear expansion coefficient of the transparent resin film becomes too large, the hardness of the first cured resin layer in the indentation test becomes too high to suppress the cracks, and the flexibility of the transparent conductive film is impaired. The linear expansion coefficient of the transparent resin film is preferably 1.0 × 10 ^-4 cm / cm · ° C. or less. The coefficient of linear expansion of the transparent resin film is preferably 6.0 × 10 ⁻⁵ cm / cm · ° C. to 9.0 × 10 ⁻⁵ cm / cm · ° C.

The tensile breaking strength of the transparent resin film is not particularly limited, but from the viewpoint of requiring a cured resin layer on both sides, 100 MPa or less is preferable, 95 MPa or less is more preferable, 90 MPa or less is further preferable, and 85 MPa or less is particularly preferable. Although the lower limit of the tensile breaking strength is not particularly limited, it is preferably 10 MPa or more, more preferably 30 MPa or more, from the viewpoint of enabling transportation by the roll-to-roll manufacturing method.

As the transparent resin film, various transparent plastic films are used. For example, as the transparent resin film, polyester resin film, cycloolefin resin film, polycarbonate resin film, acetate resin film, polyether sulfone resin film, polyamide resin film, polyimide resin film, polyolefin resin film, etc. Examples thereof include (meth) acrylic resin film, polyvinyl chloride resin film, polyvinylidene chloride resin film, polystyrene resin film, polyvinyl alcohol resin film, polyarylate resin film, polyphenylene sulfide resin film and the like. From the viewpoints of linear expansion coefficient, tensile breaking strength, high transparency and low water absorption, cycloolefin-based resin films or polycarbonate-based resin films are preferable. Further, from the viewpoint of using under a polarizing plate, a cycloolefin-based resin film is particularly preferable.

The cycloolefin-based resin film is formed of a cycloolefin-based resin and has properties such as high linear expansion coefficient, high transparency, low phase difference, and low water absorption, but has low tensile breaking strength and is roll-to-roll. It also has the property of being easily cracked and easily damaged during such a transport process. By adopting a cycloolefin-based resin film, it is possible to control the optical characteristics of the transparent conductive film.

The cycloolefin-based resin that forms the cycloolefin-based resin film is not particularly limited as long as it is a resin having a monomer unit composed of a cyclic olefin (cycloolefin). The cycloolefin-based resin used for the cycloolefin-based resin film may be either a cycloolefin polymer (COP) or a cycloolefin copolymer (COC). The cycloolefin copolymer refers to a non-crystalline cyclic olefin resin which is a copolymer of a cyclic olefin and an olefin such as ethylene.

As the cyclic olefin, there are a polycyclic cyclic olefin and a monocyclic cyclic olefin. Examples of such polycyclic cyclic olefins include norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, etilidennorbornene, butylnorbornene, dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, and tetracyclododecene. , Methyltetracyclododecene, dimethylcyclotetradodecene, tricyclopentadiene, tetracyclopentadiene and the like. Examples of the monocyclic cyclic olefin include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctadiene, cyclododecatriene and the like.

The optical film made of the above cycloolefin resin is also available as a commercial product. For example, Topas manufactured by Polyplastics, Arton manufactured by JSR, ZEONOR, ZEONEX manufactured by Zeon Corporation, Appel manufactured by Mitsui Chemicals, etc. Can be mentioned.

Polycarbonate-based resins have a high coefficient of linear expansion and properties such as low phase difference. The polycarbonate-based resin is not particularly limited, and examples thereof include aliphatic polycarbonate, aromatic polycarbonate, and aliphatic-aromatic polycarbonate. Specifically, for example, as polycarbonate (PC) using bisphenols, bisphenol A polycarbonate, branched bisphenol A polycarbonate, foamed polycarbonate, copolycarbonate, blockcopolycarbonate, polyester carbonate, polyphosphonate carbonate, diethylene glycol bisallyl carbonate (CR- 39) and the like. Polycarbonate-based resins also include those blended with other components such as bisphenol A polycarbonate blends, polyester blends, ABS blends, polyolefin blends, and styrene-maleic anhydride copolymer blends. Examples of commercially available polycarbonate resin products include "Opcon" manufactured by Ewa Co., Ltd., "Panlite" manufactured by Teijin Co., Ltd., and "Iupilon (polycarbonate containing an ultraviolet absorber)" manufactured by Mitsubishi Gas Chemical Company.

The surface of the transparent resin film is subjected to etching treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc., and undercoating treatment in advance, and the cured resin layer or transparent formed on the transparent resin film. The adhesion with the conductive layer or the like may be improved. Further, before forming the cured resin layer or the transparent conductive layer, the surface of the transparent resin film may be dust-removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

The thickness of the transparent resin film is preferably in the range of 20 to 150 μm, more preferably in the range of 25 to 100 μm, and further preferably in the range of 30 to 80 μm. If the thickness of the transparent resin film is less than the lower limit of the above range, the mechanical strength of the transparent resin film may be insufficient, and it may be difficult to roll the film base material to continuously form the transparent conductive layer. is there. On the other hand, if the thickness exceeds the upper limit of the above range, it may not be possible to improve the scratch resistance of the transparent conductive layer and the spotting characteristics for a touch panel.

The refractive index of the transparent resin film is preferably 1.45 or more, more preferably 1.45 to 1.70, and more preferably 1.50 to 1.65 from the viewpoint of ensuring transparency. Is more preferable, and 1.52 to 1.60 is particularly preferable.

(Curing resin layer)
The cured resin layer includes a first cured resin layer provided on one surface side of the transparent resin film and a second cured resin layer provided on the other surface side. Since the transparent resin film is easily scratched in each process such as forming the transparent conductive layer, patterning the transparent conductive layer, or mounting the transparent resin film on an electronic device, as described above, the first cured resin is formed on both sides of the transparent resin film. A layer and a second cured resin layer are formed.

In the present invention, the hardness of the first cured resin layer in the indentation test is 0.27 GPa or more, and the hardness of the second cured resin layer in the indentation test is less than 0.29 GPa. The hardness of the first cured resin layer by the indentation test is preferably larger than the hardness of the second cured resin layer by the indentation test. From the viewpoint of achieving both crack generation prevention and film fracture suppression, the hardness of the first cured resin layer in the indentation test is 0.29 GPa or more, and the hardness of the second cured resin layer in the indentation test is 0.29 GPa or more. , Preferably less than 0.29 GPa. The lower limit of the hardness by the indentation test of the first cured resin layer is preferably larger than the hardness by the indentation test of the second cured resin layer, and is preferably 0.20 GPa or more from the viewpoint of preventing cracks from occurring. It is preferably .27 GPa or more, more preferably 0.29 GPa or more, and further preferably 0.31 GPa or more. Although the upper limit of the hardness of the first cured resin layer by the indentation test is not particularly limited, it is preferably 1.0 GPa or less, preferably 0.8 GPa or less, from the viewpoint of preventing film breakage in roll-to-roll transfer. More preferably, it is more preferably 0.7 GPa or less.

On the other hand, the upper limit of the hardness of the second cured resin layer in the indentation test is not particularly limited, but is preferably 0.40 GPa or less, preferably 0.30 GPa or less, from the viewpoint of preventing film breakage during roll-to-roll transfer. It is more preferably less than or equal to, more preferably less than 0.29 GPa, and particularly preferably 0.285 GPa or less. Although the lower limit of the hardness of the second cured resin layer by the indentation test is not particularly limited, it is preferably 0.10 GPa or more, preferably 0.15 GPa or more, from the viewpoint of preventing film damage during roll-to-roll transfer. More preferably.

Further, from the viewpoint of both preventing crack generation and suppressing film breakage, a value obtained by subtracting the hardness of the second cured resin layer from the indentation test of the first cured resin layer (difference in hardness). = Hardness by indentation test of first cured resin layer-Hardness by indentation test of second cured resin layer) is preferably greater than 0 GPa and 1.0 GPa or less, more preferably 0.01 GPa or more and 0.5 GPa or less. It is preferable, and more preferably 0.02 GPa or more and 0.4 GPa or less.

It is preferable that the amount of plastic deformation of the first cured resin layer by the indentation test is 50 nm or less, and the amount of plastic deformation of the second cured resin layer by the indentation test is larger than 50 nm. Although the upper limit of the amount of plastic deformation by the indentation test of the first cured resin layer is not particularly limited, it is preferably 50 nm or less from the viewpoint of preventing cracks and scratches in roll-to-roll transport, preferably 45 nm. It is more preferably less than or equal to 40 nm or less. Although the lower limit of the amount of plastic deformation by the indentation test of the first cured resin layer is not particularly limited, from the viewpoint of both preventing film breakage and crack generation during roll-to-roll transfer, and further from the viewpoint of crack generation prevention. It is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more.

On the other hand, the lower limit of the amount of plastic deformation by the indentation test of the second cured resin layer is not particularly limited, but is preferably 40 nm or more, and is larger than 45 nm from the viewpoint of preventing film breakage during roll-to-roll transfer. Is more preferable, it is more preferably larger than 50 nm, and particularly preferably 52 nm or more. Although the upper limit of the amount of plastic deformation by the indentation test of the second cured resin layer is not particularly limited, it is preferably 150 nm or less, preferably 100 nm or less, from the viewpoint of both preventing film breakage and film scratching. Is more preferable.

Further, from the viewpoint of both preventing crack generation and suppressing film breakage, a value obtained by subtracting the amount of plastic deformation obtained by the pushing test of the second cured resin layer from the amount of plastic deformation obtained by the pushing test of the first cured resin layer. (Difference in amount of plastic deformation = amount of plastic deformation by pushing test of the first cured resin layer-amount of plastic deformation by pushing test of the second cured resin layer) is preferably -100 nm to 0 nm, preferably -50 nm to 0 nm. −5 nm is more preferable, and −40 nm to −10 nm is further preferable.

The refractive index of the first cured resin layer is preferably 1.45 to 1.50, more preferably 1.47 to 1.50, and 1.49 to 1 from the viewpoint of being used for the inner touch panel. It is more preferably .50. The refractive index of the second cured resin layer is preferably 1.40 to 1.60, more preferably 1.45 to 1.55, and 1.50 to 1.50 from the viewpoint of being used for the inner touch panel. It is more preferably 53.

The thicknesses of the first cured resin layer and the second cured resin layer are preferably 0.5 μm to 5 μm, more preferably 0.7 μm to 3 μm, and even more preferably 0.8 μm to 2 μm, respectively. The thickness of each cured resin layer may be the same or different, but is preferably the same from the viewpoint of work efficiency. By setting the thickness of each cured resin layer within the above range, the scratch resistance and crack resistance of the cured resin layer can be suitably balanced. If the cured resin layer is too thin, it cannot function as a hard coat layer, and scratch resistance and crack resistance cannot be obtained. On the other hand, if the cured resin layer is too thick, the flexibility of the cured resin layer as a whole is lowered, and sufficient crack resistance cannot be obtained.

(Resin composition)
The cured resin layer is a layer obtained by curing the resin composition. Here, the cured resin layer is, for example, a component A having three or more polymerizable functional groups in the molecule and having a weight average molecular weight of 200 or more and 1000 or less, and a polymerizable functional group per unit molecular weight in the molecule. A layer in which a resin composition containing a component B having a smaller number than the component A and a weight average molecular weight of more than 1000 and not more than 100,000 can be cured. In the cured resin layer, the structure derived from the component A having a weight average molecular weight of 200 or more and 1000 or less acts as a hard segment, thereby contributing to scratch resistance and crack prevention, and at the same time, the weight average molecular weight is larger than 1000 and 100,000 or less. The structure derived from the component B acting as a soft segment can contribute to crack resistance.

As the resin composition for forming each cured resin layer, one containing the above-mentioned specific components A and B is preferable, and a transparent one having sufficient strength as a film after forming the cured resin layer can be used without particular limitation. .. The resin composition forming the cured resin layer may have an increased amount of solid content of component A from the viewpoint of increasing hardness to prevent damage to the film and preventing cracks in the transparent conductive layer. By doing so, the monomer reaction points can be increased, and the hardness of the cured resin layer can be sufficiently increased. In relation to the composition of the second cured resin layer, the composition of the first cured resin layer preferably contains more component A than the second cured resin layer.

From the viewpoint of imparting flexibility and preventing film breakage in the resin composition forming the second cured resin layer, the solid content of the component B is preferably larger than the solid content of the component A. .. In the resin composition forming the second cured resin layer, the amount of the solid content of the component B is 70% by weight to 90% by weight with respect to the total amount of the solid content of the component A and the solid content of the component B. Is more preferable, and is more preferably 75% by weight to 85% by weight, and the solid content of the component A is preferably 10% by weight to 30% by weight, and preferably 15% by weight to 25% by weight. More preferred. By setting the amounts of the component A and the component B in the resin composition forming the second cured resin layer within the above ranges, appropriate flexibility can be imparted, and in the transport process by the roll-to-roll manufacturing method. It is possible to prevent the film from breaking.

Examples of the resin used in the resin composition include thermosetting resins, thermoplastic resins, ultraviolet curable resins, electron beam curable resins, and two-component mixed resins. Among these, curing treatment by ultraviolet irradiation Therefore, an ultraviolet curable resin that can efficiently form each cured resin layer by a simple processing operation is preferable.

Examples of the ultraviolet curable resin include various types such as polyester type, acrylic type, urethane type, amide type, silicone type, and epoxy type, and include ultraviolet curable type monomers, oligomers, polymers, and the like. The ultraviolet curable resin preferably used is one having an ultraviolet polymerizable functional group such as an acryloyl group, and among them, an acrylic monomer or oligomer having two or more, particularly 2 to 6 such polymerizable functional groups in the molecule. Examples thereof include those containing a level component and a polymer level component as component A and component B. Further, the ultraviolet curable resin contains an ultraviolet polymerization initiator. A three-dimensional crosslinked structure is formed after the resin composition is cured by such a polyfunctional high molecular weight component and a polyfunctional low molecular weight component, and the polyfunctional low molecular weight component mainly serves as a starting point for cross-linking of the crosslinked structure. The polyfunctional high molecular weight component, which contributes to hardness and has a smaller number of polymerizable functional groups per unit molecular weight, mainly contributes to flexibility as a soft segment.

In the present embodiment, urethane (meth) acrylate can be preferably used as the ultraviolet curable resin.

As the urethane (meth) acrylate, those containing (meth) acrylic acid, (meth) acrylic acid ester, polyol, and diisocyanate as constituent components are used. For example, by using at least one monomer of (meth) acrylic acid and (meth) acrylic acid ester and a polyol, a hydroxy (meth) acrylate having one or more hydroxyl groups is prepared, and this is reacted with diisocyanate. Urethane (meth) acrylate can be produced. One type of urethane (meth) acrylate may be used alone, or two or more types may be used in combination.

Examples of the (meth) acrylic acid ester include (meth) alkyl acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate and butyl (meth) acrylate; and cyclocyclo (meth) acrylate and the like. Alkyl (meth) acrylate and the like can be mentioned.

The polyol is a compound having at least two hydroxyl groups, for example, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1 , 4-Butandiol, 1,6-hexanediol, 1,9-Nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5- Pentandiol, hydroxypivalate neopentyl glycol ester, tricyclodecanedimethylol, 1,4-cyclohexanediol, spiroglycol, tricyclodecanedimethylol, hydrogenated bisphenol A, ethylene oxide-added bisphenol A, propylene oxide-added bisphenol A, Trimethylol ethane, trimethylol propane, glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol, glucoses, polypropylene glycol, polybutylene glycol, 1,2-butylene oxide At least one diol selected from the group consisting of a copolymer of ethylene oxide and a copolymer of propylene oxide and ethylene oxide, an aliphatic or cyclic polyether polyol, a polyester polyol, a polycarbonate polyol, a polycaprolactone polyol, and the like. Be done.

As the diisocyanate, for example, various aromatic, aliphatic or alicyclic diisocyanates can be used, and for example, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4, 4-diphenyl diisocyanis, 1,5-naphthalenediis diisis, 3,3-dimethyl-4,4-diphenyl diisocyanis, xylene diisocyanis, trimethylhexamethylene diisocyanate, 4,4-diphenylmethane diisocyanate, etc. Can be mentioned.

The blending ratio of urethane (meth) acrylate in the resin composition is not particularly limited. From the viewpoints of the flexibility of each cured resin layer, the hardness of each cured resin layer, the adhesion to the transparent resin film, etc., the blending ratio of the urethane (meth) acrylate is, for example, 10 to 90 with respect to the total weight of the resin composition. It is in the range of% by weight, preferably in the range of 20 to 80% by weight.

As the curable resin used in the resin composition for forming the curable resin layer, a reactive diluent may be provided in addition to each of the above components. Reactive diluents include 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol (meth) acrylate, and pentaerythritol, which have relatively low viscosity. Bifunctional or higher functional monomers and oligomers such as tri (meth) acrylate, trimethylolpropan tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, neopentyl glycol di (meth) acrylate, and monofunctional monomers such as N-vinyl. Acrylate esters such as pyrrolidone, ethyl acrylate and propyl acrylate, methacrylic acid esters such as ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, isooctyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate and nonylphenyl methacrylate. Kind, derivatives such as tetrahydrofurfuryl methacrylate and caprolactone variants thereof, styrene, q-methylstyrene, acrylic acid and the like, or mixtures thereof and the like can be used.

In addition to the above-mentioned materials, the resin composition shall contain commonly used additives such as plasticizers, surfactants, antioxidants, ultraviolet absorbers, leveling agents, thixotropy agents, antistatic agents, and photopolymerization initiators. Can be done. The use of thixotropy is advantageous for the formation of protruding particles on the finely uneven surface when the cured resin layer contains particles. Examples of the thixotropy agent include silica and mica having a thickness of 0.1 μm or less. The content of these additives is usually preferably about 15 parts by weight or less, preferably 0.01 to 15 parts by weight, based on 100 parts by weight of the ultraviolet curable resin.

(particle)
Each cured resin layer may independently contain particles. The first cured resin layer contains inorganic particles from the viewpoint of preventing crack generation and imparting high hardness.

As the inorganic particles contained in the first cured resin layer, transparent inorganic particles such as various metal oxides and glass can be used without limitation. For example, examples of the inorganic particles include inorganic oxide particles such as silicon oxide (silica particles) particles, hollow nanosilica particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, zirconium oxide particles, and calcium oxide particles. Therefore, one type may be used alone, or two or more types may be used in combination. The inorganic particles contained in the first cured resin layer are preferably silica particles from the viewpoint of imparting hardness and preventing the occurrence of cracks. Inorganic particles are used in combination with crosslinked or uncrosslinked organic particles or silicone-based particles made of various polymers such as polymethylmethacrylate, polystyrene, polyurethane, acrylic resin, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate. Can also be used.

The average particle size of the inorganic particles is preferably 5 to 100 nm, more preferably 10 to 50 nm, and even more preferably 20 to 40 nm from the viewpoint of transparency. In the present specification, the "average particle size" is the average particle size (D ₅₀ ) of the particle size distribution based on the volume, and is obtained by measuring a solution in which the particles are dispersed in water by a light diffraction / scattering method. Be done.

The content of the inorganic particles in the first cured resin layer is 10 to 70 in the first cured resin layer after curing from the viewpoint of preventing the occurrence of cracks and suppressing the breakage of the film. It is by weight%, preferably 15 to 60% by weight, and more preferably 20 to 55% by weight. If the content of the inorganic particles in the first cured resin layer is less than 10% by weight, the crack resistance is insufficient due to insufficient hardness, and if it exceeds 70% by weight, the flexibility is insufficient and the film breaks. May occur. Further, the amount of inorganic particles contained in the first cured resin layer is preferably larger than the content of the particles in the second cured resin layer. A resin composition containing such inorganic particles can be obtained as a commercially available product. For example, KZ6518, KZ6506, KZ6519, Z7503 manufactured by JSR Corporation and the like can be mentioned.

The particles contained in the second cured resin layer may be the same particles as the particles contained in the first cured resin layer as described above, but may be different particles. The particles contained in the second cured resin layer are preferably organic particles as described above from the viewpoint of blocking resistance and imparting flexibility, and specifically, acrylic resin particles are preferable from the viewpoint of refractive index.

(Coating composition)
The coating composition used to form the cured resin layer comprises the above resins, particles, and solvent.

The coating composition can be prepared by mixing the above resin and particles with a solvent, an additive, a catalyst and the like, if necessary. The solvent in the coating composition is not particularly limited, and is timely selected in consideration of the resin to be used, the material of the portion to be the base for coating, the coating method of the composition, and the like. Specific examples of the solvent include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, acetone, methyl isobutyl ketone and cyclohexanone; diethyl ether, isopropyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether and ethylene glycol. Ether solvents such as diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, anisole, phenetol; ester solvents such as ethyl acetate, butyl acetate, isopropyl acetate, ethylene glycol diacetate; dimethylformamide, diethylformamide, N -Amid solvents such as methylpyrrolidone; cellosolve solvents such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; alcohol solvents such as methanol, ethanol and propanol; halogen solvents such as dichloromethane and chloroform; and the like. These solvents may be used alone, or two or more of them may be used in combination. Of these solvents, ester solvents, ether solvents, alcohol solvents and ketone solvents are preferably used.

In the coating composition, the particles are preferably dispersed in the solution. As a method of dispersing the particles in the solution, various known methods such as a method of adding the particles to the resin composition solution and mixing them, a method of adding the particles previously dispersed in the solvent to the resin composition solution, and the like are used. Can be adopted.

The solid content concentration of the coating composition is preferably 1% by weight to 70% by weight, more preferably 2% by weight to 50% by weight, and most preferably 5% by weight to 40% by weight. If the solid content concentration is too low, the unevenness of the ridges on the surface of the cured resin layer becomes large in the drying step after coating, and the haze may increase. On the other hand, if the solid content concentration becomes too large, the contained components tend to aggregate, and as a result, the aggregated portion may become apparent and the appearance of the transparent conductive film may be impaired.

(Applying and curing)
Each cured resin layer can be formed by applying the above coating composition on a transparent resin film. The coating composition may be applied directly on the transparent resin film, or may be applied on an undercoat layer or the like formed on the transparent resin film.

Each cured resin layer is cured by applying a coating composition on a transparent resin film, drying the solvent if the coating composition contains a solvent, and applying heat, active energy rays, or both. Obtained by letting. Known means such as an air circulation oven and an IR heater can be used for heat, but the heat is not limited to these methods. Examples of active energy rays include ultraviolet rays, electron beams, gamma rays, etc., but are not particularly limited.

The coating method of the coating composition can be selected in a timely manner according to the situation of the coating composition and the coating process. For example, a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, and a gravure It can be applied by a coating method, a die coating method, an extrusion coating method, or the like.

A cured resin layer can be formed by curing the coating film after applying the coating composition. When the resin composition is photocurable, it can be cured by irradiating it with light using a light source that emits light having a wavelength as required. As the light to be irradiated, for example, light having an exposure amount of 150 mJ / cm ² or more, preferably light having an exposure amount of 150 mJ / cm ^{2 to} 1000 mJ / cm ² can be used. The wavelength of the irradiation light is not particularly limited, but for example, irradiation light having a wavelength of 380 nm or less can be used. It should be noted that heating may be performed during the photocuring treatment.

(Optical adjustment layer)
An optical adjustment layer can be provided between the first cured resin layer and the transparent conductive layer for the purpose of controlling the adhesion and reflection characteristics of the transparent conductive layer. The optical adjustment layer reduces the difference in reflectance between the pattern forming portion where the transparent conductive layer is formed and the pattern opening where the transparent conductive layer is removed by adjusting the difference in reflectance, and the pattern is formed. It can be provided for the purpose of making it difficult to see.

The optical adjustment layer may be one layer, two layers or more. The optical adjustment layer is formed of an inorganic substance, an organic substance, or a mixture of an inorganic substance and an organic substance. Materials for forming the optical adjustment layer include NaF (1.3), Na ₃ AlF ₆ (1.35), LiF (1.36), MgF ₂ (1.38), CaF ₂ (1.4), and the like. BaF ₂ (1.3), BaF ₂ (1.3), SiO ₂ (1.46), LaF ₃ (1.55), CeF (1.63), Al ₂ O ₃ (1.63), TIO ₂ , Ta ₂ O ₅ , ZrO ₂ , ZnO, ZnS, SiO _x (x is 1.5 or more and less than 2) and other inorganic substances [values in parentheses indicate refractive index] and refractive index is 1.4 to 1.4 to Examples thereof include organic substances such as acrylic resin, urethane resin, melamine resin, alkyd resin, and siloxane-based polymer of about 1.6. In particular, as the organic substance, it is preferable to use a thermosetting resin composed of a mixture of a melamine resin, an alkyd resin and an organic silane condensate. The optical adjustment layer can be formed by a coating method such as a gravure coating method or a bar coating method, a vacuum vapor deposition method, a sputtering method, an ion plating method, or the like using the above materials.

The thickness of the optical adjustment layer is preferably 10 nm to 200 nm, more preferably 20 nm to 150 nm, and even more preferably 20 nm to 130 nm. If the thickness of the optical adjustment layer is excessively small, it is difficult to form a continuous film. Further, if the thickness of the optical adjustment layer is excessively large, the transparency of the transparent conductive film tends to decrease, and cracks tend to easily occur in the optical adjustment layer.

The optical adjusting layer may have nanoparticles having an average particle size of 1 nm to 500 nm. The content of the nanoparticles in the optical adjustment layer is preferably 0.1% by weight to 90% by weight. The average particle size of the nanoparticles used in the optical adjustment layer is preferably in the range of 1 nm to 500 nm as described above, and more preferably 5 nm to 300 nm. Further, the content of the nanoparticles in the optical adjustment layer is more preferably 10% by weight to 80% by weight, further preferably 20% by weight to 70% by weight. By containing the nanoparticles in the optical adjustment layer, the refractive index of the optical adjustment layer itself can be easily adjusted.

Examples of the inorganic oxide forming the nanoparticles include fine particles such as silicon oxide (silica), hollow nanosilica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, and zirconium oxide. Among these, fine particles of silicon oxide (silica), titanium oxide, aluminum oxide, zinc oxide, tin oxide, and zirconium oxide are preferable. One of these may be used alone, or two or more thereof may be used in combination.

(Transparent conductive layer)
The transparent conductive layer can be provided on the first cured resin layer provided on one surface side of the transparent resin film. Further, the transparent conductive layer may be provided via the optical adjustment layer. The transparent conductive layer is one in which at least one transparent conductive layer is formed, and may have two or more transparent conductive layers. The transparent conductive layer is a thin film containing a conductive oxide of a metal as a main component, or a thin film containing a composite metal oxide containing a main metal and one or more impurity metals as a main component. As long as these conductive thin films are transparent and have conductivity, their constituent materials are not particularly limited, and Sc, Y, Si, Zr, Hf, V, Nb, Ta, Cr, Mo, W. , Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Mg, Ga, Ti, Ge, In, Sn, Pb , As, Sb, Bi, Se, Te, and I. A metal oxide containing one kind of metal as a main component selected from the group is preferably used. From the viewpoint of transparency and conductivity of the transparent conductive layer, the main metal element is preferably any of In, Zn, and Sn, and the indium-based composite oxide is most preferable. When the transparent conductive layer is a composite metal oxide containing a main metal and an impurity metal, one or more metals selected from the above group are preferably used as the impurity metal. The refractive index of the transparent conductive layer is usually about 1.95 to 2.05.

From the viewpoint of lowering the resistance of the transparent conductive layer, the impurity metal in the composite metal oxide preferably has a larger number of valence electrons than the main metal. Examples of such composite metal oxides include indium-tin composite oxide (ITO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and indium-doped zinc oxide (IZO). ) Etc. can be mentioned. Among them, indium-tin composite oxide is most preferably used from the viewpoint of forming a transparent conductive layer having low resistance and high transparency. Such an indium-tin composite oxide has a feature that the transmittance is high in the visible light region (380 nm to 780 nm) and the surface resistance value per unit area is low.

When an indium-tin composite oxide is used as the transparent conductive layer, the amount of SnO ₂ may be 0.5% by weight to 15% by weight based on the weight of In ₂ O ₃ and SnO ₂ added. It is preferably 1 to 10% by weight, more preferably 2 to 6% by weight. If the amount of SnO ₂ is too small, the durability of the ITO film may be inferior. Further, if the amount of SnO ₂ is too large, the time required for crystallization tends to be long.

The transparent conductive layer may be crystalline or amorphous. For example, when a transparent resin film is used as a base material and an ITO film is formed as a transparent conductive layer by a sputtering method, sputter film formation cannot be performed at a high temperature due to restrictions due to the heat resistance of the base material. Therefore, the transparent conductive layer immediately after film formation is often an amorphous film (a part of which may be crystallized depending on the film formation temperature). Such an amorphous transparent conductive layer has a lower transmittance than a crystalline one, and may cause problems such as a large change in resistance after a humidification heat test. From this point of view, an amorphous transparent conductive layer may be formed once and then converted into a crystal film by heating in the presence of oxygen in the atmosphere (crystallization annealing treatment). By crystallizing the transparent conductive layer, the transparency is improved, the resistance is lowered, and the humidification heat reliability is improved.

When the transparent conductive layer is not crystallized and annealed immediately after film formation (that is, when it is crystallized and annealed after storage), the amorphous film is affected by storage conditions (temperature, humidity, etc.) over time. Some of them may crystallize naturally. The state in which a part of the amorphous film is naturally crystallized can be imitated by heating the transparent conductive layer of the amorphous film under the condition of 50 ° C. for 5 days as described in Examples described later. When the crystallization annealing treatment is performed using a transparent conductive layer in which a part of the transparent conductive layer is naturally crystallized, cracks often occur on the surface of the transparent conductive layer. By using the first cured resin layer containing a predetermined amount of inorganic particles, it is possible to suppress the generation of cracks as described above due to the heat applied during the crystallization annealing treatment or the like.

The surface resistance value of the transparent conductive layer is preferably 400 Ω / □ or less, more preferably 350 Ω / □ or less, and further preferably 300 Ω / □ or less. In such a transparent conductive film having a small surface resistance value, for example, an amorphous layer of an indium tin oxide-based composite oxide is formed on a cured resin layer by a sputtering method or a vacuum vapor deposition method, and then the temperature is 80 ° C. to 200 ° C. It is obtained by heat-treating at ° C. for about 30 to 90 minutes to change the amorphous transparent conductive layer into crystalline material (crystallization annealing treatment). The means for converting is not particularly limited, but an air circulation oven, an IR heater, or the like is used.

Regarding the definition of "crystalline", a transparent conductive film having a transparent conductive layer formed on a transparent resin film is immersed in hydrochloric acid at 20 ° C. and a concentration of 5% by weight for 15 minutes, then washed with water and dried for 15 mm. The resistance between terminals is measured with a tester, and if the resistance between terminals does not exceed 10 kΩ, it is assumed that the conversion of the ITO film to crystalline material is completed.

The thickness of the transparent conductive layer is not particularly limited, but in order to form a continuous coating having a surface resistance of 1 × 10 ³ Ω / □ or less and having good conductivity, the thickness is preferably 10 nm or more. If the film thickness becomes too thick, the transparency will decrease. Therefore, the film thickness is preferably 15 to 35 nm, more preferably 20 to 30 nm. If the thickness of the transparent conductive layer is less than 15 nm, the electrical resistance of the film surface becomes high and it becomes difficult to form a continuous film. Further, if the thickness of the transparent conductive layer exceeds 35 nm, the transparency may be lowered.

The method for forming the transparent conductive layer is not particularly limited, and a conventionally known method can be adopted. Specifically, for example, a dry process such as a vacuum deposition method, a sputtering method, or an ion plating method can be exemplified. Further, an appropriate method can be adopted depending on the required film thickness.

For example, when the transparent conductive layer is formed by a sputtering method, the temperature of the transparent resin film is preferably 80 to 180 ° C. Depending on the film formation temperature, a part of the amorphous film may crystallize. In the present specification, the "temperature of the transparent resin film" is the set temperature of the base of the transparent resin film at the time of sputter film formation. For example, the temperature of the transparent resin film when the sputtering film is continuously formed by the roll sputtering apparatus is the temperature of the can roll in which the sputtering film formation is performed. Further, the substrate temperature in the case of performing sputter film formation by the single-wafer type (batch type) is the temperature of the substrate holder on which the substrate is placed.

Further, the transparent conductive layer may be patterned by etching or the like. For example, in a transparent conductive film used for a capacitance type touch panel or a matrix type resistance film type touch panel, it is preferable that the transparent conductive layer is patterned in a stripe shape. When the transparent conductive layer is patterned by etching, if the transparent conductive layer is crystallized first, it may be difficult to pattern the transparent conductive layer by etching. Therefore, the annealing treatment of the transparent conductive layer is preferably performed after the transparent conductive layer is patterned.

<Transparent conductive film>
The transparent conductive film of the present embodiment can be a transparent conductive film wound body in which a long transparent conductive film is wound in a roll shape. As the winding body of the long transparent conductive film, a roll-shaped winding body of the long transparent resin film is used, and additional layers such as the above-mentioned cured resin layer, optical adjustment layer, and transparent conductive layer are added. , Both can be formed by forming by a roll-to-roll method. In forming such a wound body, a protective film (separator) having a weak adhesive layer is attached to the surface of the transparent conductive film in consideration of slipperiness and blocking resistance, and then rolled into a roll shape. It may be wound.

<Touch panel>
The transparent conductive film of the present invention can be suitably applied to a touch panel of, for example, a capacitance type or a resistance film type.

As the touch panel, an "inner touch panel type" touch panel is preferable from the viewpoint that even a transparent conductive film having a low refractive index layer can be used. In the case of the inner touch panel, even when a first cured resin layer or the like having a relatively low refractive index is used (for example, the refractive index of the first cured resin layer = 1.45 to 1.50). Even in some cases), it does not have a large effect on visibility and can be used without problems. The configuration or type of the touch panel is not particularly limited, and it is also used for a so-called "F / F type" touch panel, a so-called "F / G type" touch panel, a so-called "F / F / P type" touch panel, and the like. be able to.

The "inner touch panel method" is a method in which the polarizing plate and the retardation plate on the upper part of the LCD module are arranged on the upper part of the touch panel. That is, in a PDA (Personal Digital Assistant) or the like equipped with a resistive touch panel as an input device, a resistive touch panel is usually mounted on an LCD module, so that an upper electrode and a lower portion are mounted. An air layer exists between the electrodes, and the decrease in transmittance due to reflection on this air layer is an obstacle to high brightness, low power consumption, etc., and as a method for solving this, " "Inner touch panel method" has been proposed.

An example of the usage mode applied to the inner touch panel method is as follows. A touch panel made of two transparent conductive films and an LCD module are attached via a double-sided adhesive sheet, and the LCD module is attached to the other surface (the surface opposite to the touch panel) of the LCD module. Further, a backlight is attached to the lower surface side surface (the surface opposite to the LCD module) of the polarizing plate via a frame-shaped double-sided adhesive tape. On the other hand, a retardation plate and a polarizing plate are provided in this order on the upper surface or the surface side surface (the surface opposite to the LCD module) of the touch panel.

When forming the touch panel, another base material such as glass or a polymer film can be attached to one or both main surfaces of the transparent conductive film via a transparent adhesive layer. For example, a laminate in which a transparent substrate is bonded to a surface of a transparent conductive film on the side where the transparent conductive layer is not formed may be formed via a transparent adhesive layer. The transparent substrate may consist of one substrate film, or may be a laminate of two or more substrate films (for example, one laminated via a transparent adhesive layer). Further, a hard coat layer can be provided on the outer surface of the transparent substrate to be attached to the transparent conductive film.

The pressure-sensitive adhesive layer used for bonding the transparent conductive film and the base material is not particularly limited as long as it has transparency. Specifically, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxys, fluorines, natural rubbers, synthetic rubbers and other rubbers, etc. A polymer based on the above polymer can be appropriately selected and used. In particular, an acrylic pressure-sensitive adhesive is preferably used because it has excellent optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness, and adhesiveness, and is also excellent in weather resistance, heat resistance, and the like.

When the transparent conductive film according to the present invention is used for forming a touch panel, it is excellent in handleability when forming a touch panel. Therefore, it is possible to manufacture a touch panel having excellent transparency and visibility with high productivity.

<Image display device>
The transparent conductive film of the present embodiment can be incorporated into an image display device. The image display device includes an image display element and the touch panel described above. The image display element generally includes a color filter on the visual side of the image display cell and a polarizing plate on the side opposite to the visual side. The image display device is not particularly limited, and examples thereof include a cathode ray tube, a plasma display, an EL display, and the like, in addition to a liquid crystal display device (LCD module). The display surface of the LCD module may be made of triacetyl cellulose (TAC) or glass. Further, the display device may be provided with a polarizing plate. Therefore, the display surface of the display device (the surface to which the double-sided adhesive sheet is attached) is usually the surface of a glass plate or a TAC film.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

(1) Push-in test (hardness, amount of plastic deformation)
A indentation test was carried out under the following conditions, and the hardness [GPa] and the amount of plastic deformation [nm] of the first cured resin layer and the second cured resin layer were measured. The sample was measured after the transparent conductive film prepared as described below was immersed in 10 wt% hydrochloric acid for 5 min, and the transparent conductive layer was etched.

Equipment: Hysiron Inc. Nano indenter used Indenter: Berkovich (triangular pyramid type)
Measurement method: Single push measurement Measurement temperature: 25 ° C
Push-in depth setting: 200 nm
Pushing speed: 10 nm / sec
Measurement atmosphere: In air Sample size: 1 cm x 1 cm
(Measuring method)
Using the above device, after holding at room temperature (25 ° C.) for 1 hour, the Berkovich diamond indenter was pushed vertically from the surface of the sample center to a depth of 200 nm to cure the first cured resin layer and the second cured resin layer. The hardness [GPa] and the amount of plastic deformation [nm] of the resin layer were measured. Using the analysis software "Triboscan Ver. 9.2.12.0", the surface indentation depth (plastic deformation amount) is obtained from the displacement and load obtained when the indenter is indented and the theoretically calculated indentation area. ) And hardness were determined. Here, the indentation depth is an index indicating the degree to which the deformed sample surface does not return to the initial state (elastic recovery does not occur) even when the indenter load becomes 0, that is, the amount of plastic deformation of the sample in the loading process. The measurement results are shown in Table 1. The formulas for calculating the difference in hardness and the difference in the amount of plastic deformation are shown below.

Difference in hardness = Hardness of the first cured resin layer-Hardness of the second cured resin layer Difference in the amount of plastic deformation = Amount of plastic deformation of the first cured resin layer-Amount of plastic deformation of the second cured resin layer (2) ) Crack confirmation test The transparent conductive film (initial resistance value 340Ω / □) immediately after film formation prepared as described below was heated under 50 ° C. conditions for 5 days to crystallize a part of the amorphous film (resistance). Value 130Ω / □). Furthermore, a sample (resistance value 100Ω / □) completely crystallized by heating at 130 ° C. for 90 minutes (crystallization annealing treatment) is subjected to a shape analysis laser microscope (KEYENCE, VK-X200, shape analysis application "VK-H1XA". , Crack observation was performed in a field of view of 1 μm × 1 μm). The measurement results are shown in FIGS. 4 to 6 and Table 1. The case where a crack occurred was evaluated as "◯", and the case where no crack did not occur was evaluated as "x".

(3) Evaluation of scratch resistance The surface of the prepared first cured resin layer was slid 10 times with a length of 10 cm while applying a load of 100 g of steel wool (φ25 mm), and then the first cured resin layer was formed. The condition of the surface was visually observed to evaluate the degree of scratches. No scratches were evaluated as "○", thin scratches on the entire surface were evaluated as "Δ", and significant scratches on the entire surface were evaluated as "x". The measurement results are shown in Table 1.

(4) Measurement of thickness The thickness was measured with a microgauge type thickness gauge (manufactured by Mitutoyo Co., Ltd.) for those having a thickness of 1 μm or more. For those having a thickness of less than 1 μm, the calculation was made based on the waveform of the interference spectrum using an instantaneous multi-photometric system (MCPD2000 manufactured by Otsuka Electronics Co., Ltd.).

(5) Linear expansion coefficient According to ASTM E831, the measurement was performed by thermomechanical analysis under the measurement conditions of 25 ° C. to 150 ° C.

(6) Measurement of surface resistance value Measured by the 4-terminal method according to JIS K7194.

(7) Measurement of Weight Average Molecular Weight The weight average molecular weight of the components in the prepared resin composition solution was measured by gel permeation chromatography (GPC). The measurement conditions of GPC are as follows.

Measuring equipment: Tosoh's trade name HLC-8120
GPC column: Tosoh's product name G4000H _XL + product name G2000H _XL + product name G1000H _XL (7.8 mmφ x 30 cm each, 90 cm in total)
Column temperature: 40 ° C
Eluent: tetrahydrofuran Flow velocity: 0.8 ml / min Inlet pressure: 6.6 MPa
Standard sample: polystyrene

(8) 180 ° Bending Test The sample was measured after immersing a transparent conductive film prepared as described below in 10 wt% hydrochloric acid for 5 min and etching the transparent conductive layer. That is, a sample having a width of 50 mm and a length of 100 mm was cut out from the COP film on which the first cured resin layer and the second cured resin layer were formed. Next, with the first cured resin layer on the inside, as shown in FIG. 3, this sample S is folded in half, the ends are bonded to each other with a commercially available adhesive tape, and this is used as a base B. It was placed. A circular weight W (500 g) having a bottom surface of 50 mm in diameter was allowed to stand on a surface having a width of 50 mm and a length of 50 mm obtained by folding in half for 10 seconds, and it was confirmed whether or not the film was broken at that time. The case where the film was not broken was evaluated as "◯", the case where the film was broken but both ends were not separated was evaluated as "Δ", and the case where the film was broken and both ends were separated was evaluated as "x". The measurement results are shown in Table 1.

(9) Transportability by roll-to-roll When a transparent conductive film was produced as described later, the transportability by an actual roll-to-roll manufacturing method was evaluated. That is, as described later, when the transparent conductive layer is formed by the roll-to-roll method, if the transparent conductive film can be conveyed without breaking, "○" is displayed, and if the transparent conductive film is broken and cannot be conveyed. Was evaluated as "x". The evaluation results are shown in Table 1.

(10) Refractive index The refractive index of each layer is specified by using an Abbe refractometer manufactured by Atago Co., Ltd. so that measurement light (sodium D line) is incident on various measurement surfaces. The measurement was performed by the measuring method. The refractive index at the measurement wavelength of 400 nm was defined as the refractive index in the present specification.

(11) Evaluation of Tensile Breaking Strength After cutting the transparent resin film base material to a width of 10 mm and a length of 130 mm, "Autograph-1kNG" (manufactured by Shimadzu Corporation) was used as a tensile tester to test samples. A tensile test was performed at a tensile speed of 300 mm / min, a distance between chucks of 50 mm, and room temperature (23 ° C.) to obtain a stress-strain curve. The stress when the transparent resin film base material was broken was calculated and used as the tensile breaking strength.

<Example 1>
(Formation of second cured resin layer)
As a material for forming the second cured resin layer, 80 parts by weight of DIC Corporation's product name "Unidic ELS-888" and 20 parts by weight of DIC Corporation's product name "Unidic RS28-605" A resin composition solution was prepared by mixing the parts. When the weight average molecular weight of the prepared resin composition solution was confirmed by gel permeation chromatography (GPC), the weight average molecular weight of the prepared resin composition solution was 200 or more and 1000 or less with respect to all the resin components. 20% by weight and 80% by weight of component B having a weight average molecular weight of 1000 to 100,000 was contained.

The prepared resin composition solution is used as a base film for a norbornene-based resin film having a thickness of 40 μm (manufactured by Nippon Zeon Corporation, trade name “Zeonoa film”, hereinafter referred to as “COP film”. Linear expansion coefficient: 7.0 × Apply to one surface of ^10-5 cm / cm · ° C, tensile breaking strength = 76 MPa, refractive index = 1.53), dry at 80 ° C for 1 minute, and immediately ozone type high pressure mercury lamp (UV intensity 180 mW / A ^second cured resin layer (refractive index = 1.51) having a thickness of 1.0 μm was formed by irradiating with ultraviolet rays at cm ² and integrated light amount: 230 mJ / cm ² ).

(Formation of first cured resin layer)
A resin composition having ultraviolet curability (manufactured by JSR Corporation, "KZ6518", 20 wt by weight of SiO ₂ particles having an average particle diameter of 20 nm is formed on the surface of the COP film on which the second cured resin layer is formed. %) Is applied, dried at 80 ° C. for 1 minute, and then immediately irradiated with ultraviolet rays with an ozone type high-pressure mercury lamp (UV intensity 160 mW / cm ² , integrated light intensity: 230 mJ / cm ² ) to a thickness of 1.0 μm. The cured resin layer of 1 was formed. The refractive index of the first cured resin layer was 1.50.

(Film formation of transparent conductive layer)
The COP film having the cured resin layers formed on both sides was put into a take-up sputtering apparatus, and a sintered body target containing indium oxide and tin oxide in a 90:10 weight ratio was attached to the first. A transparent conductive layer (refractive index = 2.00) made of amorphous indium tin oxide having a thickness of 25 nm was formed on the surface of the cured resin layer by reactive sputtering. In the obtained transparent conductive film, the surface resistance value of the transparent conductive layer was 340 Ω / □.

(Crystallization annealing of transparent conductive layer)
Then, the COP film on which the amorphous layer of indium tin oxide was formed was put into an air circulation oven by a roll-to-roll method, and heat-treated at 130 ° C. for 90 minutes to remove the transparent conductive layer. A transparent conductive film having a surface resistance value of 100 Ω / □ was prepared by converting from crystalline material to crystalline material.

<Example 2>
In Example 1, as the resin composition of the first cured resin layer, 40% by weight of the resin composition shown in Table 1 (“KZ6506” manufactured by JSR Corporation, SiO ₂ particles having an average particle diameter of 20 nm is contained. ) Was used, and a transparent conductive film was produced in the same manner as in Example 1. The refractive index of the first cured resin layer was 1.495.

<Example 3>
In Example 1, as the resin composition of the first cured resin layer, 60% by weight of the resin composition shown in Table 1 (“KZ6519” manufactured by JSR Corporation, SiO ₂ particles having an average particle diameter of 20 nm is contained. ) Was used, and a transparent conductive film was produced in the same manner as in Example 1. The refractive index of the first cured resin layer was 1.49.

<Comparative example 1>
In Example 1, except that the resin composition shown in Table 1 (manufactured by JSR Corporation, “KZ6524”, which does not contain SiO ₂ particles) was used as the resin composition of the first cured resin layer. A transparent conductive film was produced in the same manner as in Example 1. The refractive index of the first cured resin layer was 1.52.
..

<Comparative example 2>
In Example 1, as the resin composition of the first cured resin layer, 75% by weight of the resin composition shown in Table 1 (“Z7503” manufactured by JSR Corporation, SiO ₂ particles having an average particle diameter of 20 nm is contained. ) Was used, and a transparent conductive film was produced in the same manner as in Example 1. The refractive index of the first cured resin layer was 1.49.

(Results and discussion)
First, the relationship between the transparent resin film base material and the coefficient of linear expansion was examined. As a result, the linear expansion coefficient of each base material was 7.0 × 10 ^-5 cm / cm · ° C. for the cycloolefin resin film (COP film) and 6.6 × 10 for the polycarbonate resin film (PC film). ^The temperature was ^-5 cm / cm · ° C, and the polyester resin film (PET film) was 2.0 × 10 ^-5 cm / cm · ° C. When a base material having a low coefficient of linear expansion such as PET film is used, the influence on crack generation due to thermal expansion is small. Further, when a hard substrate having a high tensile breaking strength such as a PET film is used (the tensile breaking strength of the PET film = 217 MPa), it is often not necessary to form a cured resin layer on both sides of the substrate.

On the other hand, when a base material having a high coefficient of linear expansion and easy thermal expansion such as a COP film or a PC film is used, cracks are likely to occur. In the present invention, in particular, even when a substrate having a high coefficient of linear expansion such as a COP film or a PC film is used, the first curing which contains 10 to 70% by weight of inorganic particles and has a certain degree of hardness. It is considered that the formation of the resin layer can prevent thermal deformation and prevent the occurrence of cracks. Further, when a soft substrate having a low tensile breaking strength such as a COP film or a PC film is used (the tensile breaking strength of the COP film = 76 MPa, the tensile breaking strength of the PC film = 98 MPa), the cured resin is applied to both sides of the substrate. Since it is necessary to form a layer, it is considered useful in the present invention to adjust the hardness and flexibility of each cured resin layer by containing inorganic particles or the like.

Next, the obtained evaluation results are shown in Table 1. When the content of the inorganic particles in the first cured resin layer is 20 to 60% by weight as in Examples 1 to 3, it is a case where a base material having a high coefficient of linear expansion such as a COP film is used. Even when the first cured resin layer is subjected to crystallization annealing after being heated and stored at 50 ° C. for 5 days (that is, using an ITO film in which a part of the amorphous film is crystallized), the first cured resin layer is to some extent. Since it can be made hard and can prevent thermal deformation, it is possible to prevent cracks from being generated on the surface of the ITO film. Furthermore, by containing a predetermined amount of the inorganic particles, no scratches were generated in the evaluation of the scratch resistance on the first cured resin layer, and good results were obtained.

Further, in Examples 1 to 3, when the content of the inorganic particles in the first cured resin layer was 20 to 60% by weight, relatively good results of ◯ or Δ were obtained in the 180 ° bending test. .. In addition, even when used in an actual machine, the transparent conductive film could be conveyed by the roll-to-roll manufacturing method without breaking. By setting the content of the inorganic particles in the first cured resin layer to 20 to 60% by weight, the hardness of the first cured resin layer can be increased to some extent, and the second cured resin layer has flexibility. It is considered that the film can be prevented from breaking due to the above, and the occurrence of cracks can be prevented by the first cured resin layer having high curability. As a result, it is possible to achieve both the problem of preventing crack generation and the problem of suppressing film breakage.

On the other hand, when inorganic particles were not contained as in Comparative Example 1, the film could be transported roll-to-roll without breaking in the 180 ° bending test, but after being heated and stored at 50 ° C. for 5 days (that is, one of the amorphous films). When the crystallization annealing treatment was performed (using an ITO film in which the part was crystallized), cracks were generated on the surface of the ITO film. Further, in the evaluation of the scratch resistance of the first cured resin layer, scratches were also generated, and good results could not be obtained.

On the other hand, when the content of the inorganic particles in the first cured resin layer was as high as 75% by weight as in Comparative Example 2, the tendency opposite to that in Comparative Example 1 was observed. That is, although cracks did not occur on the surface of the ITO film, the surface of the ITO film was broken in the 180 ° bending test, and roll-to-roll transfer was not possible. It is presumed that the cause of the breakage in the actual machine test is that the film wrinkles occur after passing through the heating roll, the film is locally bent, and the breakage occurs.

The photographs at the time of crack occurrence are shown in FIGS. 4 to 5. FIG. 4 is a photograph of a laser microscope (× 50 times) after the crack confirmation test in Comparative Example 1. It was visually confirmed that cracks were generated on the surface of the ITO film. Further, FIG. 5 is a photograph of an optical microscope after the crack confirmation test in Comparative Example 1. Further, although not shown, in the cracks, the base material and the first cured resin layer thermally expand due to the heat applied during the crystallization annealing treatment, whereas the transparent conductive layer does not easily expand thermally. It was found that it was formed due to this difference in thermal expansion. On the other hand, FIG. 6 is a photograph of a laser microscope (× 50 times) after the crack confirmation test in Example 1, and it was visually confirmed that the occurrence of cracks could be suppressed.

1 Transparent resin film 2 First cured resin layer 2'Second cured resin layer 3 Transparent conductive layer 4 Optical adjustment layer 10, 11 Transparent conductive film

Claims (10)

A transparent conductive film having a second cured resin layer, a transparent resin film, a first cured resin layer, and a transparent conductive layer in this order.
The transparent resin film has a coefficient of linear expansion of 5.0 × 10 ^-5 cm / cm · ° C. or higher.
The hardness of the first cured resin layer in the indentation test is 0.27 GPa or more, and the hardness of the second cured resin layer in the indentation test is less than 0.29 GPa.
The first cured resin layer is a transparent conductive film containing 10 to 70% by weight of inorganic particles. The transparent conductive film according to claim 1, wherein the refractive index of the first cured resin layer is 1.45 to 1.50. The transparency according to claim 1 or 2, wherein the hardness of the first cured resin layer by the indentation test is 0.29 GPa or more, and the hardness of the second cured resin layer by the indentation test is less than 0.29 GPa. Conductive film. Any one of claims 1 to 3, wherein the amount of plastic deformation of the first cured resin layer by the indentation test is 50 nm or less, and the amount of plastic deformation of the second cured resin layer in the indentation test is larger than 50 nm. The transparent conductive film according to. Any one of claims 1 to 4, wherein the value obtained by subtracting the hardness of the second cured resin layer from the indentation test of the first cured resin layer from the hardness of the first cured resin layer in the indentation test is greater than 0 GPa and 1.0 GPa or less. The transparent conductive film according to the item. The transparent conductive film according to any one of claims 1 to 5, further comprising one or more optical adjustment layers between the first cured resin layer and the transparent conductive layer. The transparent conductive film according to any one of claims 1 to 6, wherein the transparent resin film is a cycloolefin resin film or a polycarbonate resin film. The transparent conductive film according to any one of claims 1 to 7, wherein the inorganic particles are silica particles. The transparent conductive film according to any one of claims 1 to 8, which is used for an inner touch panel. A touch panel including the transparent conductive film according to any one of claims 1 to 9.