Transparent conductive film, method for production thereof and touch panel therewith

The present invention relates to a transparent conductive film having transparency in the visible light region and having a transparent conductor layer provided on a film substrate via an undercoat layer, and a method for producing the same. Furthermore, the present invention relates to a touch panel provided with the transparent conductive film.

The transparent conductive film of the present invention is used for display methods such as liquid crystal displays and electroluminescence displays, transparent electrodes in touch panels, etc., as well as for preventing static electricity and blocking electromagnetic waves of transparent articles. In particular, the transparent conductive film of the present invention is preferably used in touch panel applications. Above all, it is suitable for a capacitance coupling type touch panel application.

The touch panel includes an optical method, an ultrasonic method, a capacitance method, a resistance film method, and the like depending on the position detection method. In the resistive film type touch panel, the transparent conductive film and the glass with the transparent conductor layer are arranged to face each other via a spacer, and a current is passed through the transparent conductive film to measure the voltage in the glass with the transparent conductor layer. It has a structure that makes it possible. On the other hand, the capacitance type touch panel basically has a transparent conductive layer on the base material, is characterized by having no moving parts, and has high durability and high transmittance, so that it can be used in vehicles, etc. It is applied in.

In the touch panel, for example, a first undercoat layer, a second undercoat layer, and a transparent conductor layer are formed in this order from the side of the film base material on one surface of the transparent film base material. Sexual films have been proposed (Patent Document 1).

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2002-326301</text></patcit></p>

<p> The transparent conductive film may pattern a transparent conductor layer. However, the difference between the patterned portion that patterns the transparent conductor layer and the non-patterned portion becomes clear, and the appearance as a display element deteriorates. In particular, in a capacitance coupling type touch panel, since the transparent conductor layer is used on the incident surface side, a display element having a good appearance is required even when the transparent conductor layer is patterned.</p><p> An object of the present invention is to provide a transparent conductive film in which a transparent conductor layer is patterned and has a good appearance, and a method for producing the same. Another object of the present invention is to provide a touch panel provided with the transparent conductive film.</p>

<p> As a result of diligent studies to solve the above problems, the inventors of the present application have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.</p><p> That is, the present invention is a transparent conductive film having a transparent conductor layer via at least one undercoat layer on one side or both sides of a transparent film base material. The present invention relates to a transparent conductive film in which the transparent conductor layer is patterned and the non-patterned portion having no transparent conductor layer has at least one undercoat layer.</p><p> In the transparent conductive film, when there are at least two undercoat layers, at least the undercoat layer farthest from the transparent film base material is preferably patterned in the same manner as the transparent conductor layer. Is.</p><p> When the transparent conductive film has at least two undercoat layers, it is preferable that at least the undercoat layer farthest from the transparent film base material is formed of an inorganic substance. As an undercoat layer formed of an inorganic substance, SiO₂Membranes are suitable.</p><p> In the transparent conductive film, the undercoat layer of the first layer from the transparent film base material is preferably formed of an organic substance.</p><p> In the transparent conductive film, the difference between the refractive index of the transparent conductor layer and the refractive index of the undercoat layer is preferably 0.1 or more.</p><p> In the transparent conductive film, If the patterned transparent conductor layer is provided via two undercoat layers, The undercoat layer, which is the first layer from the transparent film substrate, has a refractive index (n) of 1.5 to 1.7 and a thickness (d) of 100 to 220 nm. The second undercoat layer from the transparent film substrate has a refractive index (n) of 1.4 to 1.5 and a thickness (d) of 20 to 80 nm. The transparent conductor layer has a refractive index (n) of 1.9 to 2.1 and a thickness (d) of 15 to 30 nm. The total optical thickness (n × d) of each layer is preferably 208 to 554 nm.</p><p> Further, the difference (Δnd) between the total optical thickness of the patterned transparent conductor layer and the two undercoat layers and the optical thickness of the undercoat layer in the non-patterned portion is 40 to 130 nm. preferable.</p><p> In the transparent conductive film of the present invention, at least two transparent conductive films are laminated via a transparent adhesive layer so that the patterned transparent conductor layer is arranged on at least one side. You can use what you have.</p><p> Further, in the transparent conductive film of the present invention, a transparent substrate is attached to one side of the transparent conductive film via a transparent pressure-sensitive adhesive layer so that the patterned transparent conductor layer is arranged on one side. The one that is combined can be used.</p><p> The transparent conductive film is preferably used for a touch panel. The touch panel is suitable for a capacitance coupling type touch panel.</p><p> The present invention is a method for producing the transparent conductive film. A step of preparing a transparent conductive film having a transparent conductive layer on one or both sides of a transparent film substrate via at least one undercoat layer, and The present invention relates to a method for producing a transparent conductive film, which comprises a step of etching and patterning the transparent conductor layer with an acid.</p><p> In the above manufacturing method, when there are at least two undercoat layers, After the process of etching and patterning the transparent conductor layer with acid, At least, it has a step of etching the undercoat layer farthest from the transparent film substrate with alkali.</p><p> In the method for producing a transparent conductive film, a step of patterning the transparent conductor layer and then a step of annealing and crystallizing the patterned transparent conductor layer can be included.</p><p> The present invention also relates to a touch panel provided with the transparent conductive film.</p>

<p> In the transparent conductive film, when the transparent conductor layer is provided in a pattern, the gap between the patterns is clarified due to the difference in reflectance between the patterned portion and the non-patterned portion, and the appearance is impaired. In the transparent conductive film of the present invention, the transparent conductor layer is patterned, but the undercoat layer is provided in the non-patterned portion, and the reflectance difference between the patterned portion and the non-patterned portion can be suppressed to a small size. , The problem caused by the clarification between patterns is solved and the appearance is improved. Further, by providing the undercoat layer in the non-patterned portion, the film base material is not exposed, the generation of oligomers in the film base material can be suppressed, and the appearance is good. Further, by providing the undercoat layer in the non-patterned portion, the patterned transparent conductor layers are insulated between each other, and the patterned transparent conductor layer allows the transparent conductive film to be used. Spreads. Such a transparent conductive film is preferably used in a touch panel. In particular, it is preferably used for a capacitance coupling type touch panel.</p>

<figref num="1">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="2">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="3">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="4">It is sectional drawing which shows the transparent conductive film which concerns on Comparative Example 1. FIG.</figref><figref num="5">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="6">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="7">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="8">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="9">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="10">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="11">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="12">It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention.</figref><figref num="13">It is a top view which shows an example of the pattern of the transparent conductive film of this invention.</figref>

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the transparent conductive film of the present invention. The transparent conductive film of FIG. 1 has a transparent conductor layer 3 on one side of a transparent film base material 1 via an undercoat layer 2. The transparent conductor layer 3 is patterned. In each figure, the fact that the transparent conductor layer 3 is patterned is indicated by having a pattern portion a having the transparent conductor layer 3 and a non-patterned portion b having no transparent conductor layer 3. .. Further, the non-patterned portion b has the undercoat layer 2. Figures 2 and 3 show the case where there are two undercoat layers 2. In FIGS. 2 and 3, undercoat layers 21 and 22 are provided in this order from the side of the transparent film base material 1. FIG. 2 shows a case where the non-patterned portion b has the undercoat layers 21 and 22. In FIG. 3, the undercoat layer 22 farthest from the transparent film substrate 1 is patterned in the same manner as the transparent conductor layer 3. In FIG. 3, the non-patterned portion b has an undercoat layer 21. That is, when the undercoat layer 2 is two layers, the non-pattern portion b has at least the undercoat layer 21 which is the first layer from the side of the transparent film base material 1. Although FIGS. 2 and 3 illustrate the case where the undercoat layer 2 has two layers, the undercoat layer 2 may have three or more layers. Even when the undercoat layer 2 has three or more layers, the non-pattern portion b has at least the undercoat layer 21 which is the first layer from the side of the transparent film base material 1. The undercoat layer above the first layer may or may not be patterned. When the undercoat layer 2 is at least two layers, it is preferable to control the reflectance difference between the pattern portion a and the non-pattern portion b to be small. Especially when the undercoat layer 2 is at least two layers, the undercoat layer farthest from the transparent film substrate (as shown in FIG. 3, when the undercoat layer 2 is two layers, the undercoat layer 22). Is patterned in the same way as the transparent conductor layer 3, but the pattern part a and the non-pattern This is preferable for controlling the difference in reflectance of part b to be small. Note that FIG. 4 shows a case where a patterned transparent conductor layer 3 is provided on one side of the transparent film base material 1 without interposing the undercoat layer 2.

FIG. 5 is also a cross-sectional view showing an example of the transparent conductive film of the present invention. Although FIG. 5 is described with the same configuration as that of FIG. 1, naturally, the same configuration as that described with reference to FIGS. 2 and 3 can be applied to FIG. The transparent conductive film of FIG. 5 has a transparent conductive layer 3 patterned on both sides of the transparent film base material 1 via an undercoat layer 2. The transparent conductive film of FIG. 5 has patterned transparent conductor layers 3 on both sides, but only one side may be patterned. Further, in the transparent conductive film of FIG. 5, the pattern portion a and the non-pattern portion b of the patterned transparent conductor layer 3 on both sides match, but these do not have to match, and various types are required. It can be appropriately patterned on both sides depending on the embodiment. The same applies to other figures.

6 to 9 are also cross-sectional views showing an example of the transparent conductive film of the present invention. In the transparent conductive films of FIGS. 6 to 9, two transparent conductive films shown in FIGS. 1 or 5 are laminated via a transparent adhesive layer 4. Further, the transparent conductive films obtained by laminating in FIGS. 6 to 9 are laminated so that the patterned transparent conductor layer 3 is arranged on at least one surface. In FIGS. 6 to 7, two transparent conductive films shown in FIG. 1 are laminated via a transparent adhesive layer 4. In FIG. 6, a patterned transparent conductor layer 3 of another transparent conductive film is laminated on the transparent film base material 1 of the transparent conductive film shown in FIG. 1 via a transparent pressure-sensitive adhesive layer 4. This is the case. FIG. 7 shows a case where the transparent film base materials 1 of the transparent conductive film shown in FIG. 1 are laminated with each other via the transparent adhesive layer 4. In FIGS. 8 to 9, the transparent conductive film shown in FIG. 1 and the transparent conductive film shown in FIG. 5 are laminated via the transparent adhesive layer 4. In FIG. 8, the patterned transparent conductor layer 3 of the transparent conductive film shown in FIG. 1 and the patterned transparent conductor layer 3 on one side of the transparent conductive film shown in FIG. 5 are transparent adhesive layers. This is the case when they are laminated via 4. In FIG. 9, the transparent film base material 1 of the transparent conductive film shown in FIG. 1 and the patterned transparent conductor layer 3 on one side of the transparent conductive film shown in FIG. 5 are interposed via a transparent adhesive layer 4. This is the case when they are laminated. 6 to 9 illustrate the case where two transparent conductive films shown in FIGS. 1 or 5 are laminated via the transparent adhesive layer 4, but are shown in FIGS. 1 or 5. Three or more transparent conductive films can be appropriately combined according to the aspects of FIGS. 6 to 9 described above. Although FIGS. 6 to 9 have the same configurations as those in FIGS. 1, the same configurations as those described in FIGS. 2 and 3 can be naturally applied to FIGS. 6 to 9.

Further, the transparent conductive film of the present invention can be used in a mode in which the pressure-sensitive adhesive layer 4 is provided. The pressure-sensitive adhesive layer 4 is laminated so that the patterned transparent conductor layer 3 is arranged on one side of the transparent conductive film. FIG. 10 shows a case where the transparent pressure-sensitive adhesive layer 4 is laminated on the transparent film base material 1 of the transparent conductive film shown in FIG. FIG. 11 shows a case where the transparent adhesive layer 4 is laminated on the patterned transparent conductor layer 3 on one side of the transparent conductive film shown in FIG. In FIGS. 10 and 11, the separator S is provided on the pressure-sensitive adhesive layer 4. Similarly, in the case where two or more transparent conductive films are laminated as shown in FIGS. 6 to 9, the patterned transparent conductor layer 3 is similarly arranged on one side of the transparent conductive film. The pressure-sensitive adhesive layer 4 can be laminated as described above.

Further, the transparent substrate 5 can be attached to one side of the transparent conductive film via the transparent adhesive layer 4. In the transparent conductive film to which the transparent substrate 5 is attached, the transparent substrate 5 is attached so that the patterned transparent conductor layer 3 is arranged on one side. FIG. 12 shows a structure in which the transparent substrate 5 is bonded to the transparent film substrate 1 (the surface on which the transparent conductor layer 3 is not provided) of the transparent conductive film of FIG. 1 via the transparent adhesive layer 4. It is a transparent conductive film. The transparent substrate 5 may be made of one substrate film, or may be a laminate of two or more substrate films (laminated via a transparent adhesive layer). Further, FIG. 12 shows a case where the hard coat layer (resin layer) 6 is provided on the outer surface of the transparent substrate 5. Although FIG. 12 is an example of the transparent conductive film of FIG. 1, the same structure can be applied to the transparent conductive film of FIGS. 2 and 3. It can also be applied to a transparent conductive film having the structures shown in FIGS. 5 to 9.

The film base material 1 is not particularly limited, but various transparent plastic films are used. For example, as the material, polyester resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth) acrylic resin, polyvinyl chloride resin, poly Examples thereof include vinylidene chloride-based resin, polystyrene-based resin, polyvinyl alcohol-based resin, polyarylate-based resin, and polyphenylene sulfide-based resin. Of these, polyester-based resins, polycarbonate-based resins, and polyolefin-based resins are particularly preferable.

Further, a polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, a thermoplastic resin having a substituted and / or unsubstituted imide group in the (A) side chain and a (B) side chain. Examples thereof include resin compositions containing a thermoplastic resin having a substituted and / unsubstituted phenyl and a nitrile group. Specifically, a polymer film having a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be used.

The thickness of the film substrate 1 is preferably in the range of 2 to 200 μm, and more preferably in the range of 2 to 100 μm. If the thickness of the film base material 1 is less than 2 μm, the mechanical strength of the film base material 1 is insufficient, and the film base material 1 is rolled to form the undercoat layer 2 and the transparent conductor layer 3 continuously. Operation may be difficult. On the other hand, if the thickness exceeds 200 μm, it may not be possible to improve the scratch resistance of the transparent conductor layer 3 and the striking characteristics for a touch panel.

The surface of the film base material 1 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 undercoat layer 2 provided on the film base material 1 The adhesion to the film base material 1 may be improved. Further, before providing the undercoat layer 2, dust may be removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

In the present invention, even when the transparent conductor layer 3 is patterned, by having the undercoat layer 2, it is possible to obtain a display element having a good appearance. From this point of view, the refractive index of the undercoat layer 2 is preferably such that the difference between the refractive index of the transparent conductor layer 3 and the refractive index of the undercoat layer is 0.1 or more. The difference between the refractive index of the transparent conductor layer 3 and the refractive index of the undercoat layer is preferably 0.1 or more and 0.9 or less, and more preferably 0.1 or more and 0.6 or less. The refractive index of the undercoat layer 2 is usually 1.3 to 2.5, more preferably 1.38 to 2.3, and further preferably 1.4 to 2.3.

The undercoat layer 2 can be formed of an inorganic substance, an organic substance, or a mixture of an inorganic substance and an organic substance. For example, as inorganic substances, NaF (1.3), Na₃AlF₆(1.35), LiF (1.36), MgF₂(1.38), CaF₂(1.4), BaF₂(1.3), SiO₂(1.46), LaF₃(1.55), CeF₃(1.63), Al₂O₃Examples include inorganic substances such as (1.63) [the numerical value in parentheses of each of the above materials is the refractive index of light]. Among these, SiO₂, MgF₂, A1₂O₃Etc. are preferably used. In particular, SiO₂Is preferable. In addition to the above, a composite oxide containing about 10 to 40 parts by weight of cerium oxide and about 0 to 20 parts by weight of tin oxide can be used with respect to indium oxide.

Examples of the organic substance include acrylic resin, urethane resin, melamine resin, alkyd resin, siloxane-based polymer, and organic silane condensate. At least one of these organic substances is used. In particular, as the organic substance, it is desirable to use a thermosetting resin composed of a mixture of a melamine resin, an alkyd resin and an organic silane condensate.

The undercoat layer 2 is provided between the transparent film base material 1 and the transparent conductor layer 3, and does not have a function as a conductor layer. That is, the undercoat layer 2 is provided as a dielectric layer so that it can be insulated between the patterned transparent conductor layers 3. Therefore, the undercoat layer 2 usually has a surface resistance of 1 × 10.⁶Ω / or more, preferably 1 × 10⁷Ω / or more, more preferably 1 × 10⁸Ω / or more. There is no particular upper limit on the surface resistance of the undercoat layer 2. Generally, the upper limit of the surface resistance of the undercoat layer 2 is the measurement limit, 1 × 10.¹³Ω / , but 1 × 10¹³It may exceed Ω / .

It is preferable that the undercoat layer of the first layer from the transparent film base material 1 is formed of an organic substance in order to pattern the transparent conductor layer 3 by etching. Therefore, when the undercoat layer 2 is one layer, it is preferable that the undercoat layer 2 is formed of an organic substance.

Further, when there are at least two undercoat layers 2, at least the undercoat layer farthest from the transparent film base material 1 is formed of an inorganic substance, and the transparent conductor layer 3 is patterned by etching. It is preferable to do so. When the undercoat layer 2 has three or more layers, it is preferable that the undercoat layer above the second layer from the transparent film base material 1 is also formed of an inorganic substance.

The undercoat layer formed of an inorganic substance can be formed as a dry process such as a vacuum deposition method, a sputtering method, an ion plating method, or a wet method (coating method). As the inorganic substance forming the undercoat layer, as described above, SiO₂Is preferable. In the wet method, SiO is applied by applying silica sol or the like.₂A film can be formed.

From the above, when two undercoat layers 2 are provided, it is preferable that the first undercoat layer 21 is formed of an organic substance and the second undercoat layer 22 is formed of an inorganic substance.

The thickness of the undercoat layer 2 is not particularly limited, but is usually about 1 to 300 nm, preferably 5 to 300 nm, from the viewpoint of optical design and the effect of preventing oligomer generation from the film substrate 1. Is. When two or more undercoat layers 2 are provided, the thickness of each layer is about 5 to 250 nm, preferably 10 to 250 nm.

As described above, the transparent conductor layer 3 preferably has a refractive index difference of 0.1 or more from that of the undercoat layer 2. The refractive index of the transparent conductor layer 3 is usually about 1.95 to 2.05.

The constituent material of the transparent conductor layer 3 is not particularly limited, and is selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, and tungsten. Metal oxides of at least one metal are used. The metal oxide may further contain the metal atoms shown in the above group, if necessary. For example, indium oxide containing tin oxide, tin oxide containing antimony, and the like are preferably used.

The thickness of the transparent conductor layer 3 is not particularly limited, but its surface resistance is 1 × 10.³In order to form a continuous coating having good conductivity of Ω / or less, 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 is less than 15 nm, the surface electrical resistance becomes high and it becomes difficult to form a continuous coating. In addition, if it exceeds 35 nm, the transparency will decrease.

The method for forming the transparent conductor layer 3 is not particularly limited, and a conventionally known method can be adopted. Specifically, for example, a vacuum vapor deposition method, a sputtering method, and an ion plating method can be exemplified. Further, an appropriate method can be adopted depending on the required film thickness. After the transparent conductor layer 3 is formed, it can be crystallized by subjecting it to an annealing treatment in the range of 100 to 150 ° C, if necessary. Therefore, the film base material 1 preferably has a heat resistance of 100 ° C. or higher, more preferably 150 ° C. or higher. In the present invention, the transparent conductor layer 3 is etched and patterned. Since etching may become difficult when the transparent conductor layer 3 is crystallized, it is preferable to perform the annealing treatment of the transparent conductor layer 3 after patterning the transparent conductor layer 3. Further, when the undercoat layer 2 is etched, it is preferable to perform the annealing treatment of the transparent conductor layer 3 after the etching of the undercoat layer 2.

The transparent conductor layer 3 is patterned on the undercoat layer 2. In the patterning, various patterns can be formed depending on the application to which the transparent conductive film is applied. The patterning of the transparent conductor layer 3 forms a patterned portion and a non-patterned portion, and examples of the shape of the patterned portion include a striped shape and the like. FIG. 13 is an example of a case where the transparent conductor layer 3 is formed in a striped shape according to the top view of the transparent conductive film of the present invention, and the pattern portion a and the non-pattern portion b of the transparent conductor layer 3 are striped. It is formed in a shape. In FIG. 13, the width of the pattern portion a is larger than the width of the non-pattern portion b, but the width is not limited to this range.

The method for producing a transparent conductive film of the present invention is not particularly limited as long as the undercoat layer and the transparent conductor layer have the above-mentioned structure on one side or both sides of the transparent film base material. For example, as usual, a transparent conductive film having a transparent conductor layer is prepared on one side or both sides of a transparent film base material from the side of the film base material via at least one undercoat layer, and then the transparent film base material is prepared. It can be manufactured by etching and patterning the conductor layer. At the time of etching, the transparent conductor layer is covered with a mask for forming a pattern, and the transparent conductor layer is etched with an etching solution.

Since indium oxide containing tin oxide and tin oxide containing antimony are preferably used as the transparent conductor layer, an acid is preferably used as the etching solution. Examples of the acid include inorganic acids such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid and phosphoric acid, organic acids such as acetic acid, mixtures thereof, and aqueous solutions thereof.

When there are at least two undercoat layers, only the transparent conductor layer can be etched and patterned, and the transparent conductor layer is etched with an acid and patterned, and then at least a transparent film. The undercoat layer farthest from the substrate can be etched and patterned in the same manner as the transparent conductor layer. Preferably, a transparent conductor layer other than the first undercoat layer can be etched and patterned from the transparent film base material in the same manner as the transparent conductor layer.

When etching the undercoat layer, the undercoat layer is covered with a mask for forming a pattern similar to that when the transparent conductor layer is etched, and the undercoat layer is etched with an etching solution. As described above, the undercoat layer above the second layer is SiO₂Since an inorganic substance such as the above is preferably used, an alkali is preferably used as the etching solution. Examples of the alkali include aqueous solutions of sodium hydroxide, potassium hydroxide, ammonia, tetramethylammonium hydroxide and the like, and mixtures thereof. The transparent conductor layer of the first layer is preferably formed of an organic substance that is not etched by an acid or an alkali.

In the transparent conductive film of the present invention, when a patterned transparent conductor layer is provided via two undercoat layers, the refractive index (n) and thickness (d) of each layer in the pattern portion are provided. ) And the total optical thickness (n × d) of each of the layers are as follows, which is preferable from the viewpoint that the difference in reflectance between the patterned portion and the non-patterned portion can be designed to be small.

The undercoat layer of the first layer from the transparent film substrate preferably has a refractive index (n) of 1.5 to 1.7, more preferably 1.5 to 1.65, and further preferably 1.5 to 1.6. The thickness (d) is preferably 100 to 220 nm, more preferably 120 to 215 nm, and further preferably 130 to 210 nm.

The undercoat layer of the second layer from the transparent film substrate preferably has a refractive index (n) of 1.4 to 1.5, more preferably 1.41 to 1.49, and further preferably 1.42 to 1.48. The thickness (d) is preferably 20 to 80 nm, more preferably 20 to 70 nm, and further preferably 20 to 60 nm.

The transparent conductor layer preferably has a refractive index (n) of 1.9 to 2.1, more preferably 1.9 to 2.05, and further preferably 1.9 to 2.0. The thickness (d) is preferably 15 to 30 nm, more preferably 15 to 28 nm, and further preferably 15 to 25 nm.

The total optical thickness (n × d) of each of the above layers (first undercoat layer, second undercoat layer, transparent conductor layer) is preferably 208 to 554 nm, more preferably 230 to 500 nm, and further. Is preferably 250 to 450 nm.

Further, it is preferable that the difference (Δnd) between the total optical thickness of the pattern portion and the optical thickness of the undercoat layer of the non-pattern portion is 40 to 130 nm. The difference in optical thickness (Δnd) is preferably 40 to 120 nm, more preferably 40 to 110 nm.

As described above, in the transparent conductive film of the present invention, at least two sheets are laminated via the transparent adhesive layer 4 so that the patterned transparent conductor layer 3 is arranged on at least one side. Can be done. Further, the transparent adhesive layer 4 can be laminated on the transparent conductive film of the present invention so that the patterned transparent conductor layer 3 is arranged on one side.

Further, on one side of the transparent conductive film of the present invention, the transparent pressure-sensitive adhesive layer 4 is arranged so that the patterned transparent conductor layer 3 is arranged on one side of the transparent conductive film to which the transparent substrate 5 is attached. The transparent substrate 5 can be attached to the transparent substrate 5 via the above. The transparent substrate 5 may have a composite structure in which at least two transparent substrate films are bonded by a transparent adhesive layer. The patterning of the transparent conductor layer 3 can also be applied to the transparent conductive film having such a structure.

The thickness of the transparent substrate 5 is usually preferably 90 to 300 μm, and more preferably controlled to 100 to 250 μm. Further, when formed by a plurality of substrate films forming the transparent substrate 5, the thickness of each substrate film is 10 to 200 μm, further 20 to 150 μm, and the transparent substrate including the transparent pressure-sensitive adhesive layer in these substrate films. The total thickness as 5 is controlled so as to fall within the above range. Examples of the substrate film include those similar to the film substrate 1 described above.

When the transparent conductive film (for example, the film base material 1) and the transparent base material 5 are bonded together, the pressure-sensitive adhesive layer 4 is provided on the transparent base material 5 side, and the film base material 1 is bonded to the pressure-sensitive adhesive layer 4. Alternatively, conversely, the pressure-sensitive adhesive layer 4 may be provided on the film base material 1 side, and the transparent base material 5 may be attached to the pressure-sensitive adhesive layer 4. In the latter method, the pressure-sensitive adhesive layer 4 can be formed continuously by rolling the film base material 1 into a roll shape, which is more advantageous in terms of productivity. Further, the transparent substrate 5 can be laminated on the film substrate 1 by sequentially laminating a plurality of substrate films with an adhesive layer. As the transparent pressure-sensitive adhesive layer used for laminating the substrate film, the same transparent pressure-sensitive adhesive layer 4 as described below can be used. Further, when the transparent conductive films are bonded to each other, the laminated surface of the transparent conductive film on which the pressure-sensitive adhesive layer 4 is laminated can be appropriately selected, and the transparent conductive films can be bonded to each other.

The pressure-sensitive adhesive layer 4 can be used without particular limitation 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 appropriate wettability, cohesiveness, adhesiveness, and other adhesive properties, and is also excellent in weather resistance, heat resistance, and the like.

Depending on the type of pressure-sensitive adhesive that is the constituent material of the pressure-sensitive adhesive layer 4, it is possible to improve the anchoring force by using an appropriate pressure-sensitive adhesive undercoat. Therefore, when such a pressure-sensitive adhesive is used, it is preferable to use a pressure-sensitive adhesive undercoat.

The adhesive undercoating agent is not particularly limited as long as it is a layer capable of improving the anchoring force of the adhesive. Specifically, for example, a silane coupling agent having a reactive functional group such as an amino group, a vinyl group, an epoxy group, a mercapto group, and a chlor group in the same molecule and a hydrolyzable alkoxysilyl group, the same molecule. A titanate-based coupling agent having a hydrolyzable hydrophilic group containing titanium and an organic functional group, and aluminum having a hydrolyzable hydrophilic group containing aluminum in the same molecule and an organic functional group. So-called coupling agents such as nate-based coupling agents, and resins having an organic reactive group such as epoxy-based resins, isocyanate-based resins, urethane-based resins, and ester-urethane-based resins can be used. From the viewpoint of industrial ease of handling, a layer containing a silane coupling agent is particularly preferable.

Further, the pressure-sensitive adhesive layer 4 can contain a cross-linking agent according to the base polymer. Further, the pressure-sensitive adhesive layer 4 may be filled with, for example, natural or synthetic resins, glass fibers, glass beads, metal powder or other inorganic powder, pigments, colorants, antioxidants, etc., if necessary. Appropriate additives can also be blended. Further, the pressure-sensitive adhesive layer 4 may be provided with transparent fine particles to impart light diffusivity.

The transparent fine particles include, for example, conductive inorganic fine particles such as silica, calcium oxide, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle size of 0.5 to 20 μm. One or more suitable particles such as crosslinked or uncrosslinked organic fine particles made of an appropriate polymer such as polymethylmethacrylate and polyurethane can be used.

The pressure-sensitive adhesive layer 4 is usually used as a pressure-sensitive adhesive solution in which a base polymer or a composition thereof is dissolved or dispersed in a solvent and has a solid content concentration of about 10 to 50% by weight. As the solvent, an organic solvent such as toluene or ethyl acetate or a solvent depending on the type of pressure-sensitive adhesive such as water can be appropriately selected and used.

For example, after the transparent substrate 5 is adhered, the pressure-sensitive adhesive layer 4 has scratch resistance of the transparent conductor layer provided on one surface of the film substrate 1 and a dot for a touch panel due to its cushioning effect. It has the function of improving the characteristics, so-called pen input durability and surface pressure durability. From the viewpoint of exerting this function better, the elastic modulus of the adhesive layer 4 is set to 1 to 100 N / cm.²It is desirable to set the range and thickness of 1 μm or more, usually 5 to 100 μm. When the thickness is the same, the above effect is sufficiently exhibited, and the adhesion between the transparent substrate 5 and the film substrate 1 is also sufficient. If it is thinner than the above range, the durability and adhesion cannot be sufficiently ensured, and if it is thicker than the above range, problems such as transparency may occur. The elastic modulus and thickness of the pressure-sensitive adhesive layer 4 applied to the transparent conductive film are the same as described above in other embodiments.

The elastic modulus is 1 N / cm²If it is less than, the pressure-sensitive adhesive layer 4 becomes inelastic, so that it is easily deformed by pressure to cause unevenness on the film base material 1 and the transparent conductor layer 3. In addition, the adhesive tends to squeeze out from the machined cut surface, and the scratch resistance of the transparent conductor layer 3 and the effect of improving the spotting characteristics for a touch panel are reduced. On the other hand, the elastic modulus is 100 N / cm²If it exceeds, the adhesive layer 4 becomes hard and its cushioning effect cannot be expected. Therefore, it is difficult to improve the scratch resistance of the transparent conductor layer 3, the pen input durability for the touch panel, and the surface pressure durability. Tends to be.

Further, if the thickness of the adhesive layer 4 is less than 1 μm, the cushioning effect cannot be expected. Therefore, the scratch resistance of the transparent conductor layer 3, the pen input durability for the touch panel, and the surface pressure durability should be improved. Tends to be difficult. On the other hand, if it is too thick, the transparency will be impaired, and it will be difficult to obtain good results in terms of the formation of the adhesive layer 4, the workability of bonding the transparent substrate 5, and the cost.

The transparent substrate 5 bonded via the adhesive layer 4 imparts good mechanical strength to the film substrate 1, and in addition to pen input durability and surface pressure durability, in particular, curls. It contributes to the prevention of such occurrences.

When the pressure-sensitive adhesive layer 4 is transferred using the separator S, for example, as such a separator S, a migration prevention layer and / or a release layer is laminated on at least a surface of a polyester film that adheres to the pressure-sensitive adhesive layer 4. It is preferable to use a polyester film or the like.

The total thickness of the separator S is preferably 30 μm or more, and more preferably 60 to 100 μm. This is to suppress deformation (dents) of the pressure-sensitive adhesive layer 4, which is expected to be generated by foreign matter or the like that has entered between the rolls when the pressure-sensitive adhesive layer 4 is stored in a roll state after being formed.

The migration prevention layer can be formed of an appropriate material for preventing the migration of the migration component in the polyester film, particularly the low molecular weight oligomer component of the polyester. As the material for forming the migration prevention layer, an inorganic substance, an organic substance, or a composite material thereof can be used. The thickness of the migration prevention layer can be appropriately set in the range of 0.01 to 20 μm. The method for forming the migration prevention layer is not particularly limited, and for example, a coating method, a spray method, a spin coating method, an in-line coating method, or the like is used. Further, a vacuum vapor deposition method, a sputtering method, an ion plating method, a spray pyrolysis method, a chemical plating method, an electroplating method and the like can also be used.

As the release layer, one made of an appropriate release agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide can be formed. The thickness of the release layer can be appropriately set from the viewpoint of the release effect. In general, from the viewpoint of handleability such as flexibility, the thickness is preferably 20 μm or less, more preferably 0.01 to 10 μm, and particularly preferably 0.1 to 5 μm. .. The method for forming the release layer is not particularly limited, and the same method as the method for forming the migration prevention layer can be adopted.

In the coating method, spray method, spin coating method, and in-line coating method, ionizing radiation curable resins such as acrylic resin, urethane resin, melamine resin, and epoxy resin, and aluminum oxide and silicon dioxide on the resin. , Mica and the like can be mixed. When using the vacuum deposition method, sputtering method, ion plating method, spray thermal decomposition method, chemical plating method or electroplating method, gold, silver, platinum, palladium, copper, aluminum, nickel, chromium, titanium, iron, Metal oxides made of cobalt or tin, alloys thereof and the like, and other metal compounds made of steel iodide and the like can be used.

Further, if necessary, a hard coat layer (resin layer) 6 for the purpose of protecting the outer surface may be provided on the outer surface of the transparent substrate 5 (the surface opposite to the adhesive layer 4). .. As the hard coat layer 6, for example, a cured film made of a curable resin such as a melanin resin, a urethane resin, an alkyd resin, an acrylic resin, or a silicone resin is preferably used. The thickness of the hard coat layer 6 is preferably 0.1 to 30 μm. If the thickness is less than 0.1 μm, the hardness may be insufficient. Further, if the thickness exceeds 30 μm, cracks may occur in the hard coat layer 6 or curls may occur in the entire transparent substrate 5.

Further, the transparent conductive film of the present invention may be provided with an antiglare treatment layer or an antireflection layer for the purpose of improving visibility. When used for a resistive touch panel, an antiglare treatment layer or an antireflection layer is provided on the outer surface of the transparent substrate 5 (the surface opposite to the adhesive layer 4) as in the case of the hard coat layer 6. be able to. Further, an antiglare treatment layer and an antireflection layer can be provided on the hard coat layer 6. On the other hand, when used in a capacitive touch panel, the antiglare treatment layer and the antireflection layer may be provided on the transparent conductor layer 3.

The constituent material of the antiglare treatment layer is not particularly limited, and for example, an ionizing radiation curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used. The thickness of the antiglare treatment layer is preferably 0.1 to 30 μm.

As the antireflection layer, titanium oxide, zirconium oxide, silicon oxide, magnesium fluoride and the like are used. In order to further exhibit the antireflection function, it is preferable to use a laminate of a titanium oxide layer and a silicon oxide layer. In the laminated body, a titanium oxide layer having a high refractive index (refractive index: about 1.8) is formed on the hard coat layer 6, and a silicon oxide layer having a low refractive index (refractive index: about 1.45) is formed on the titanium oxide layer. The formed two-layer laminate, and further, a four-layer laminate in which a titanium oxide layer and a silicon oxide layer are formed in this order on the two-layer laminate is preferable. By providing the antireflection layer of such a two-layer laminate or a four-layer laminate, it is possible to uniformly reduce the reflection of visible light in the wavelength region (380 to 780 nm).

The transparent conductive film of the present invention can be suitably applied to touch panels such as an optical method, an ultrasonic method, a capacitance method, and a resistance film method. In particular, it is suitable for a capacitive touch panel. Further, the transparent conductive film of the present invention is, for example, an electrophoresis method, a twist ball method, a thermal rewritable method, an optical writing liquid crystal method, a polymer dispersion type liquid crystal method, a guest host liquid crystal method, a toner display method, a chromism method. , Can be suitably used for flexible display elements such as electric field precipitation method.

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. Further, in each example, parts and% are all based on weight.

&lt;Refractive index&gt; The refractive index of each layer was measured by using an Abbe refractometer manufactured by Atago Co., Ltd. so that the measurement light was incident on various measurement surfaces and by a predetermined measurement method shown on the refractometer.

&lt;Thickness of each layer&gt; For films having a thickness of 1 μm or more, such as a film substrate, a transparent substrate, a hard coat layer, and an adhesive layer, measurements were performed with a microgauge type thickness gauge manufactured by Mitutoyo. In the case of layers such as a hard coat layer and an adhesive layer where it is difficult to directly measure the thickness, the total thickness of the base material provided with each layer is measured, and the film thickness of each layer is calculated by subtracting the thickness of the base material. did.

The thickness of the first undercoat layer, the second undercoat layer, the ITO film, etc. is based on the interference spectrum using MCPD2000 (trade name), which is an instantaneous multi-photometric system manufactured by Otsuka Electronics Co., Ltd. Calculated based on the waveform.

&lt;Surface resistance of undercoat layer&gt; The surface electrical resistance (Ω / ) of the undercoat layer was measured using a surface high resistance tester manufactured by Mitsubishi Chemical Corporation in accordance with the double ring method conforming to JIS K 6911 (1995).

(Example 1) (Formation of undercoat layer) A thermosetting resin with a weight ratio of 2: 2: 1 melamine resin: alkyd resin: organic silane condensate on one surface of a film substrate made of polyethylene terephthalate film (hereinafter referred to as PET film) with a thickness of 25 μm. The first undercoat layer having a thickness of 185 nm was formed by the refractive index n = 1.54) of light. Next, silica sol (Colcoat P, manufactured by Colcoat Co., Ltd.) is diluted with ethanol so that the solid content concentration becomes 2%, and is applied onto the undercoat layer of the first layer by the silica coating method, and then 150. Dry and cure at ° C for 2 minutes to obtain a second undercoat layer (SiO) with a thickness of 33 nm.₂A film and a refractive index of light 1.46) were formed. The surface resistance after forming the undercoat layer of the first layer and the second layer is 1 × 10 for both.¹²It was Ω / or higher.

(Formation of transparent conductor layer) Next, on the second undercoat layer, a sintered material of 97% by weight of indium oxide and 3% by weight of tin oxide was applied in an atmosphere of 0.4 Pa consisting of 98% argon gas and 2% oxygen gas. By the reactive sputtering method used, an ITO film having a thickness of 22 nm (refractive index of light of 2.00) was formed to obtain a transparent conductive film.

(Formation of hard coat layer) As a material for forming the hard coat layer, 100 parts of acrylic / urethane resin (Unidic 17-806 manufactured by Dainippon Ink and Chemicals Co., Ltd.) and hydroxycyclohexylphenyl ketone as a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd.) Irgacure 184) 5 parts were added to prepare a toluene solution diluted to a concentration of 30% by weight.

The material for forming the hard coat layer was applied to one surface of a transparent substrate made of a PET film having a thickness of 125 μm, and dried at 100 ° C. for 3 minutes. Immediately after that, ozone type high pressure mercury lamp (energy density 80W / cm)², 15 cm condensing type) UV irradiation was performed with two lamps to form a hard coat layer with a thickness of 5 μm.

(Manufacturing of laminated transparent conductive film) Next, on the surface of the transparent substrate opposite to the hard coat layer forming surface, a thickness of about 20 μm and an elastic modulus of 10 N / cm.²A transparent acrylic pressure-sensitive adhesive layer was formed. The pressure-sensitive adhesive layer composition is composed of 100 parts of an acrylic copolymer having a weight ratio of butyl acrylate, acrylic acid and vinyl acetate of 100: 2: 5 and 1 part of an isocyanate-based cross-linking agent. Using. The transparent conductive film (the side on which the transparent conductive layer is not formed) was bonded to the pressure-sensitive adhesive layer side to prepare a laminated transparent conductive film.

(Patterning by etching ITO film) A photoresist patterned in a stripe pattern is applied to the transparent conductor layer of the laminated transparent conductive film, dried and cured, and then immersed in 5% hydrochloric acid (hydrogen chloride aqueous solution) at 25 ° C for 1 minute. Then, the ITO film was etched.

(Patterning by etching the second undercoat layer) After etching the ITO film, the photoresist was continuously laminated and immersed in a 2% sodium hydroxide aqueous solution at 45 ° C for 3 minutes to etch the second undercoat layer. Then, the photoresist was removed.

(Crystallization of transparent conductor layer) After etching the second undercoat layer, the ITO film was crystallized by heat treatment at 140 ° C. for 90 minutes.

Example 2 In Example 1, the same operation as in Example 1 was performed except that the undercoat layer of the second layer was not patterned by etching, to prepare a laminated transparent conductive film in which the ITO film was patterned.

Example 3 In Example 1, the same operation as in Example 1 was performed except that the thickness of the undercoat layer of the first layer was changed to 35 nm and the undercoat layer of the second layer was not formed. A laminated transparent conductive film in which the film was patterned was produced.

Example 4 In Example 1, the same operation as in Example 1 was performed except that the thickness of the undercoat layer of the first layer was changed to 150 nm, and a laminated transparent conductive film in which the ITO film was patterned was produced.

Example 5 In Example 1, the same operation as in Example 1 was performed except that the thickness of the undercoat layer of the first layer was changed to 150 nm and the pattern was not formed by etching the undercoat layer of the second layer. , A laminated transparent conductive film in which an ITO film was patterned was produced.

In Examples 2 to 5, the surface resistance after forming the undercoat layer of the first layer and the second layer is 1 × 10 for both.¹²It was Ω / or higher.

Comparative example 1 In Example 1, the same operation as in Example 1 was performed except that the undercoat layer of the first layer and the undercoat layer of the second layer were not formed, and the ITO film was patterned. A film was made.

Comparative example 2 In Example 1, an ITO film having a thickness of 33 nm was provided instead of the undercoat layer of the first layer, the thickness of the undercoat layer of the second layer was changed to 60 nm, and the second layer was formed. The same operation as in Example 1 was performed except that the undercoat layer was not patterned by etching to prepare a laminated transparent conductive film in which the ITO film (transparent conductor layer on the surface) was patterned. The surface resistance after forming the first undercoat layer (ITO film) is 2 × 10.²The surface resistance after forming the second undercoat layer, which was Ω / , was 4 × 10.²It was Ω / .

The laminated transparent conductive films (samples) of Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2.

&lt;Surface resistance value of ITO film&gt; The surface electrical resistance (Ω / ) of the ITO film was measured using the two-terminal method.

&lt;Resistance between ITO film patterns&gt; The electrical resistance (Ω) of the independently existing pattern part of the ITO film was measured by a tester to evaluate whether or not it was insulated. 1x10⁶If it is Ω or more, it can be judged that it is insulated. The tester used was a custom digital tester "CDM-2000D".

&lt;Light transmittance&gt; The visible light transmittance at a light wavelength of 550 nm was measured using a spectrophotometer UV-240 manufactured by Shimadzu Corporation.

&lt;Average reflectance of 450 to 650 nm, Y value of reflection&gt; Using the integrating sphere measurement mode of the spectrophotometer U4100 manufactured by Hitachi, Ltd., the reflection spectrum was measured at a reflection incident angle of 10 degrees, and the average reflectance and Y value in the 450 to 650 nm region were calculated. In the above measurement, a light-shielding layer is formed on the back surface side (hard coat layer side) of the laminated transparent conductive film (sample) by using a black spray, and there is almost no reflection of the back surface of the sample or light incident from the back surface side. The measurement was performed in the state. The calculation of reflected color is the standard light D specified in JIS Z 8720.₆₅Was adopted, and the measurement was performed under the condition of a double field of view. The average reflectance and the Y value were measured for the patterned part (ITO film) and the non-patterned part (etched part), respectively. Table 2 also shows the difference in reflectance between the patterned portion and the non-patterned portion (Δreflectance) and the difference in Y value (ΔY value).

&lt;Appearance evaluation&gt; The sample was placed on a black plate with the transparent conductor layer side facing up, and whether or not the patterned portion and the non-patterned portion could be visually distinguished was evaluated according to the following criteria. : It is difficult to distinguish between the patterned part and the non-patterned part. : The patterned part and the non-patterned part can be slightly distinguished. X: The patterned part and the non-patterned part can be clearly distinguished.

<tables num="1"><img file="JP5422575B2_D0001.tif" /></tables>

In Table 1, AC (layer) indicates an undercoat layer.

<tables num="2"><img file="JP5422575B2_D0002.tif" /></tables>

From Tables 1 and 2, it can be seen that the transparent conductive film of the present invention has a patterned transparent conductor layer, but has a good appearance.

1 Film base material 2 Undercoat layer 3 Transparent conductor layer 4 Adhesive layer 5 transparent substrate 6 hard coat layer a Pattern part b Non-patterned part