JP3569557B2 - Transparent conductive sheet for transparent touch panel - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a transparent conductive sheet for an optically isotropic transparent touch panel which is used to be superimposed below a polarizing plate of a liquid crystal display element.
[0002]
[Prior art]
In recent years, transparent touch panels (touch keys, touch switches) that allow input by simply touching a display screen with a finger or pressing with a pen have become widespread. An input is achieved by superimposing a touch panel on a display screen such as a cathode ray tube or the like and directly pressing it with a finger or a pen. The position pressed by a finger or a pen is recognized as XY coordinates and input to a computer. Computers range from electronic organizers and mobile phones to large computers.
[0003]
The transparent conductive sheet used for the above-mentioned transparent touch panel has basically a layer structure of a conductive layer (especially, an ITO layer) / a polymer film. When used as a touch panel, two transparent conductive sheets are used. The conductive layer side of the conductive sheet is used to be opposed to the conductive sheet via a spacer.
[0004]
Japanese Patent Application Laid-Open No. 62-115613 discloses a conventional touch panel in which electrodes are formed by etching the ITO film surfaces of two transparent conductive films having an ITO thin film, and upper and lower electrodes are opposed to each other via a spacer. It is stated that the film has a structure, and in the invention of the publication itself, a conductive film for a touch panel comprising a UV-curable resin hard coat film / a transparent plastic film / a UV-curable visible light transmittance adjusting film / ITO thin film is proposed. are doing. As the transparent plastic film, a polyester film, a polyethersulfone film, a polycarbonate film and the like are used, but in the examples, a polyester film is used.
[0005]
JP-A-5-50561 discloses that a conventional transparent touch panel includes a transparent plastic film such as a polyester film provided with a transparent conductive thin film on an entire surface or a part of one surface thereof, such that the transparent conductive thin film is opposed to the transparent plastic film. It is stated that it is made by arranging via a dot spacer. In the invention of the publication itself, a transparent conductive film having a center line average roughness of 0.05 to 5.0 μm on one surface and a transparent conductive thin film formed on the other surface is used. As the film, polyethylene terephthalate, polycarbonate, polyethersulfone, etc. can be used. In the examples, an upper sheet in which an ITO thin film is formed on one side of a biaxially oriented polyethylene terephthalate film, and a biaxially oriented polyethylene terephthalate A transparent touch panel has been manufactured in which a coating agent containing fine particles is applied to one side of the film, dried, and a lower sheet having an ITO thin film formed on the other side is disposed via a dot spacer so that the ITO thin film faces each other. .
[0006]
JP-A-5-338086 describes the structure of a conventional transparent touch panel in the same manner as described above. In the invention of the publication itself, one surface has a center line average roughness of 0.05 to 5.0 μm. Yes, a transparent conductive film having a transparent conductive thin film formed on its surface is used. As the film, polyethylene terephthalate, polycarbonate, polyethersulfone, polystyrene, cellulose triacetate, and the like can be used. In the examples, a sheet in which an ITO thin film is formed on one surface of a biaxially stretched polyethylene terephthalate film, A transparent touch panel in which a coating agent containing fine particles is applied to one surface of an axially stretched polyethylene terephthalate film, dried, and a sheet having an ITO thin film formed on the coated surface is disposed via a dot spacer so that the ITO thin film faces each other. Has been produced. A biaxially stretched polyethylene terephthalate film is coated with a coating agent containing fine particles on one side, dried, and furthermore, a sheet in which an ITO thin film is formed on the coated surface is disposed via a dot spacer so that the ITO thin film faces each other. A touch panel is also disclosed.
[0007]
Japanese Patent Application Laid-Open No. 62-131416 describes that a laminate of a polyester film and a conductive layer is known as a conventional laminated film for a touch switch. In the invention of the publication itself, an abrasion-resistant layer B having a surface electric resistance of 10 ¹² Ω / □ or less, an organic polymer film substrate A, and a transparent conductive layer C having a surface electric resistance of 3 × 10 ³ Ω / □ or less are used. Use a laminated film for a touch switch laminated in the order of B / A / C. Here, as the organic polymer film substrate A, a polyethylene terephthalate film, polycarbonate, polypropylene or the like is used, but in the examples, a biaxially stretched polyethylene terephthalate film is used.
[0008]
JP-A-63-174212 discloses a transparent electrode sheet having a layer configuration of [transparent insulating layer /] transparent insulating film / transparent electrode / transparent insulating layer, and a transparent touch panel using the same. [] Indicates an arbitrary layer. Although a biaxially stretched polyester film is used in the examples as the transparent insulating film, it is described that polyamide, polyether sulfone, polyarylate, polyolefin, cellulose resin, polyvinyl chloride, and the like can also be used.
[0009]
Although there is no description about the use of the touch panel, JP-A-6-64105 discloses a transparent polymer film substrate 1 (polyether sulfone, polyether ether ketone, polyester, polycarbonate, polyolefin, especially the first two). In contrast, the transparent conductive layer 3 and the oxidized organosilicon polymer layer 2 were separated from each other by 1/2/3, 2/1/3, 21/2/3, 3/21/2. 3 shows a gas-barrier transparent conductive laminate laminated in an order such as / 3. Since this laminate is a conductive film having transparency in the visible light region and low transmittance of gases such as oxygen and water vapor, it is said to be suitable for application to liquid crystal display devices and the like.
[0010]
[Problems to be solved by the invention]
As described in the above-mentioned literature, a transparent touch panel basically includes two transparent conductive sheets each having a layer structure of “conductive layer (especially, ITO layer) / polymer film”, and has a conductive structure. It has a structure in which the layers are opposed to each other with a spacer interposed therebetween.
[0011]
By the way, a normal transparent touch panel is used so as to be superimposed on the uppermost layer of a liquid crystal display element. Therefore, attention must be paid to transparency, but optical isotropy cannot be considered. Therefore, as a polymer film, a polyester film (that is, a biaxially stretched polyethylene tertalate film) is considered in consideration of mechanical properties, surface smoothness, hardness, heat resistance, solvent resistance, scratch resistance, moisture permeability and cost. ) Is generally used, and even if such a film having no optical isotropy is used as a base, no serious problem occurs.
[0012]
However, when a transparent touch panel is used in such a manner that the transparent touch panel is superimposed on the uppermost layer of the liquid crystal display element, the reflection of light is inevitably increased and visibility becomes insufficient. The demands have not been fully met.
[0013]
In order to improve visibility, a method of installing a transparent touch panel under a polarizing plate of a liquid crystal display element is being studied, and this type of touch panel will be a promising next-generation or second-generation touch panel. It is expected to be deaf. In this case, the base film of the transparent conductive sheet is required to have optical isotropy because of the incorporation under the polarizing plate, and is required to be a polyester film (biaxially stretched polyethylene terephthalate or the like) conventionally used. A film having no high optical isotropy cannot be used.
[0014]
The present inventors have been studying a transparent touch panel installed under a polarizing plate of a liquid crystal display element for some time, but the visibility is improved only by using a conventionally known optical isotropic film as a base film. It was not possible to produce a touch panel having the expected performance in terms of improvement in light reflection, prevention of light reflection, and other basic characteristics.
[0015]
The inventions of JP-A-5-50561 and JP-A-5-338086 are based on the premise that the liquid crystal display element is used by being superimposed on the uppermost layer of the liquid crystal display element. By forming on a rough surface with a line average roughness in the range of 0.05 to 5.0 μm, the occurrence of color fringes and the occurrence of sticking are prevented, but the amount of light transmitted is reduced due to reflection scattering on the surface. Tend. Further, in this embodiment, since the rough surface is formed by coating with a resin solution containing particles, there is also a disadvantage that a streak is easily formed by a coater.
[0016]
Under such a background, the present invention is a transparent conductive sheet for an optically isotropic transparent touch panel which is used to be superimposed under a polarizing plate of a liquid crystal display element, and has visibility and light transmission amount. A transparent conductive sheet for a transparent touch panel that can be remarkably improved and has properties such as heat resistance, solvent resistance, hardness, stiffness (rigidity), scratch resistance, adhesion of a transparent conductive layer, and moisture permeability. The purpose is to provide.
[0017]
[Means for Solving the Problems]
The transparent conductive sheet for a transparent touch panel of the present invention is a transparent conductive sheet for an optically isotropic transparent touch panel which is used to be superimposed under a polarizing plate of a liquid crystal display element, and includes an optically isotropic substrate film (1 ) double-sided provided with a non-solvent type of the active energy ray curable resin cured product layer (2) on the surface is fine in diameter from 1 to 100 microns m its one radiation-curable resin cured layer (2a) Characterized by being formed on a convex rough surface having hemispherical ridges (p), and further provided with a transparent conductive layer (3) on the other active energy ray-curable resin cured layer (2b). It is.
[0018]
Hereinafter, the present invention will be described in detail. In the following, the “small gap” in “a pair of rolls arranged in parallel with a slight gap” refers to “a small gap enough to hold two films described below and a resin liquid described later”. ".
[0018]
As the optically isotropic substrate film (1), a film of polycarbonate, polyarylate, polyether sulfone, polysulfone or the like is used, and a polycarbonate film is particularly important.
[0020]
As the optically isotropic substrate film (1), a film obtained by a casting method is preferably used from the viewpoint of optical isotropicity and adhesion to an active energy ray-curable resin cured material layer (2) described below. Can be The film exemplified above can also be manufactured by an extrusion method.However, even if the film obtained by the extrusion method has optical isotropy, the film has good adhesion to the active energy ray-curable resin cured product layer (2). Therefore, a step of providing an anchor coating layer in advance is required, which is industrially disadvantageous.
[0021]
The optically isotropic substrate film (1) has a retardation value of 15 nm or less (preferably 10 nm or less), a visible light transmittance at 550 nm of 70% or more (preferably 80% or more), and a glass transition point of 100 ° C. It is particularly desirable that this is the case. When the retardation value exceeds 15 nm, optical isotropy is lost to cause coloring and interference light, and the amount of light reflection increases, resulting in reduced image visibility. If the visible light transmittance is less than 70%, the brightness when used for a touch panel is insufficient. When the glass transition point is lower than 100 ° C., heat resistance and dimensional stability are insufficient, and it is difficult to form a transparent conductive layer such as ITO, and even if it can be formed, its adhesiveness is insufficient. .
[0022]
The thickness of the optically isotropic substrate film (1) is not limited, but is usually 20 to 250 μm, preferably 50 to 180 μm.
[0023]
The active energy ray-curable resin constituting the non-solvent type active energy ray-curable resin cured material layer (2) includes adhesiveness to both the optically isotropic substrate film (1) and the transparent conductive layer (3), In consideration of heat resistance, solvent resistance, hardness, stiffness (rigidity) and the like, silicone acrylate, epoxy acrylate or urethane acrylate is suitably used, and silicone acrylate is particularly important.
[0024]
Although the thickness of the active energy ray-curable resin cured product layer (2) is not particularly limited, it is often 2 to 100 μm, particularly 3 to 50 μm.
[0025]
When providing a non-solvent type active energy ray-curable resin cured material layer (2) on both sides of the optically isotropic substrate film (1), first, a pair of rolls arranged in parallel with a slight gap isotropic substrate film (1) and the first mold film (S ₁₎ is supplied, together with ejecting the active energy ray-curable resin liquid non-solvent type towards the gap of the roll, the direction of biting the both rolls together , So that the active energy ray-curable resin liquid is sandwiched between the optically isotropic base film (1) and the first mold film (S ₁ ). It is desirable to form an active energy ray-curable resin cured product layer (2) by irradiating a ray (ultraviolet ray or electron beam) to cure the resin liquid. After the active energy ray irradiation, heat treatment may be performed as necessary to complete the curing. Thus, a laminated film having a layer structure of an optical isotropic substrate film (1) / active energy ray curable resin cured product layer (2) / the first mold film (S ₁₎ is obtained.
[0026]
Next, the laminated film obtained above is supplied to a pair of rolls arranged in parallel with a slight gap so that the optically isotropic substrate film (1) is on the inner side, and the second mold film is provided. (S ₂ ) is also supplied, and both rolls are rotated in a direction to bite each other, so that the active energy ray-curing type is formed between the optically isotropic substrate film (1) side of the laminated film and the second mold film (S ₂ ). The resin liquid is sandwiched, and the active energy ray (ultraviolet ray or electron beam) is irradiated in such a sandwiched state to cure the resin liquid. I do. After the active energy ray irradiation, heat treatment may be performed as necessary to complete the curing. As a result, a laminated film having a layer structure of (S ₂ ) / (2) / (1) / (2) / (S ₁ ) is obtained, and the mold film (S ₁ ), ( S ₂ ) is peeled off.
[0027]
As the mold film (S) ((S ₁ ), (S ₂ )) in the above, a biaxially oriented polyester film, a biaxially oriented polypropylene film, or the like is suitably used. When these films are used as a mold film (S), they can be smoothly separated from the interface between (S) and (2) after the formation of the active energy ray-curable resin cured material layer (2).
[0028]
In addition, by adopting the method of forming the active energy ray-curable resin cured material layer (2) using the mold film (S) as described above, the film thickness accuracy is improved and the active energy ray-curable resin liquid is formed of silicone acrylate. Such a material that absorbs moisture in the air and easily causes cloudiness does not cause such trouble. Therefore, it is industrially advantageous as compared with the case where the active energy ray-curable resin cured material layer (2) is formed by a coating method.
[0029]
In the present invention, as described above, the non-solvent type active energy ray-curable resin cured material layer (2) is provided on both sides of the optically isotropic substrate film (1). the surface of the object layer (2a) is formed in a convex shape rough surface (p) having raised fine hemispherical diameter from 1 to 100 microns m.
[0030]
In this case, formation of the convex rough surface on the surface of the one radiation-curable resin cured layer (2a) (p) is, as the template film (S), the particle size from 1 to 100 microns m by embossing This can be achieved by using a film having a concave rough surface (d) obtained by pressing the fine spherical projections.
[0031]
In addition, the formation of the convex rough surface (p) of the surface of the active energy ray-curable resin cured material layer (2a) is within ± 0.05 of the refractive index of the cured product as the active energy ray-curable resin liquid. can be achieved by using a resin solution obtained by blending a fine and transparent spherical particles of a particle size from 1 to 100 microns m (b) providing a very close refractive index of. As the spherical particles (b) at this time, inorganic particles, organic particles obtained by dropping or dispersing a resin liquid in a dispersion medium and then cured, organic particles obtained by a suspension polymerization method, and the like are used. Spherical fine spherical particles are suitable. The blending amount of the spherical particles (b) is, for example, often about 5 to 50% by weight. The formation of the active energy ray-curable resin cured product layer (2a) by this method is also performed while holding the resin liquid between the optically isotropic base film (1) and the mold film (S), so that the force in the direction of displacement is reduced. It does not work, so there is no risk of streaking as in the coating method.
[0032]
The surface of the other active energy ray-curable resin cured product layer (2b) is usually formed on a smooth surface using a smooth film as a mold film (S). The surface of the energy ray-curable resin cured product layer (2b) may be formed in a similar rough surface, and the transparent conductive layer (3) may be provided thereon.
[0033]
Further, in the present invention, when the refractive index of the optically isotropic substrate film (1) is n ₁ and the refractive index of the active energy ray-curable resin cured product layer (2) is n ₂ ,
n ₂ <1.5 (i)
n ₁ −n ₂ > 0.1 (ii)
It is desirable to select and set the types and forming conditions of the optically isotropic substrate film (1) and the active energy ray-curable resin cured material layer (2) so as to satisfy both of the above relationships. The condition (i) is a measure to reduce the surface reflection of the incident light. The condition (ii) is a method for reducing the reflection at the interface between the active energy ray-curable resin cured product layer (2) and the optically isotropic substrate film (1).
[0034]
After obtaining the laminated film having the layer configuration of (S) / (2a) / (1) / (2b) / (S) as described above, the mold film (S) is peeled off at an appropriate stage. Removed to (2a) / (1) / (2b) (the (S) on the (2a) side may be left) and transparent on the other active energy ray-curable resin cured layer (2b) A conductive layer (3) is provided. Thereby, a transparent conductive sheet for a transparent touch panel having a layer configuration of (2a) / (1) / (2b) / (3) is obtained.
[0035]
Here, examples of the transparent conductive layer (3) include layers such as ITO, InO ₂ , SnO ₂ , ZnO, Au, Ag, Pt, and Pd, and ITO is particularly important. The layer is formed by a sputtering method, a vacuum evaporation method, an ion plating method, a sol-gel method, a coating method, or the like, and is particularly preferably formed by a sputtering method. This transparent conductive layer (3) can be multi-layered.
[0036]
The thickness of the transparent conductive layer (3) is often, for example, 100 to 700 angstroms, particularly 150 to 600 angstroms, for example, when ITO is used. The surface resistance of the sheet at this time is, for example, 100 to 1000 Ω / □, and preferably 200 to 600 Ω / □.
[0037]
The transparent conductive layer (3) is used as a whole electrode or a pattern electrode by forming a resist and etching after forming the whole electrode, depending on the intended use.
[0038]
When producing a transparent touch panel, typically, a transparent conductive sheet having a layer configuration of (2a) / (1) / (2b) / (3) obtained as described above, separately the same method Transparent conductive sheet having a layer configuration of (2b) / (1) / (2b) / (3) (in some cases, a layer configuration of (2a) / (1) / (2b) / (3)) It is sufficient that the transparent conductive layer (3) side of the two sheets is opposed to each other and that a dot spacer having a thickness of, for example, about 0.02 to 1.0 mm is interposed between the two sheets.
[0039]
The transparent touch panel thus obtained has a liquid crystal display in which the (2a) side of the transparent conductive sheet having the layer configuration of (2a) / (1) / (2b) / (3) is on the incident light side. It is incorporated under the polarizing plate on the incident light side of the element. If a transparent conductive sheet with a transparent conductive layer (3) formed on both sides as in (3) / (2b) / (1) / (2b) / (3) is used as the lower sheet of the transparent touch panel, The touch panel can also serve as an electrode substrate on the incident light side of the cell.
[0040]
[Action]
In the transparent transparent conductive sheet for a touch panel of the present invention, convex rough surface having raised fine hemispherical surface diameter from 1 to 100 microns m of one of the active energy ray curable resin cured layer (2a) (p), and its surface is to be the surface on the incident light side when the touch panel is assembled, so that it passes through the polarizing plate and forms the surface of the active energy ray-curable resin cured material layer (2a). The incident light that has reached the rough convex surface (p) enters the active energy ray-curable resin cured product layer (2a) without being reflected regardless of the direction from which it enters.
[0041]
In addition, the refractive index n ₂ and the n ₂ of a refractive index n ₁ and the active energy ray curable resin cured layer of the optical isotropic substrate film (1) (2) <1.5 (i)
n ₁ −n ₂ > 0.1 (ii)
(I) further reduces the surface reflection of incident light, and (ii) cures the active energy ray-curable resin cured material layer (2) and the optically isotropic substrate film (1). The reflection at the interface with the surface becomes small.
[0042]
Therefore, a transparent touch panel using this transparent conductive sheet can be used not only to be superimposed under a polarizing plate of a liquid crystal display element, but also to significantly improve visibility and light transmission. Moreover, since the active energy ray-curable resin cured material layer (2) is provided on both sides of the optically isotropic substrate film (1), even if a film such as polycarbonate is used as the optically isotropic substrate film (1), heat resistance is high. , Solvent resistance, hardness, stiffness (rigidity), scratch resistance, adhesion of the transparent conductive layer, and moisture impermeability.
[0043]
【Example】
Next, the present invention will be further described with reference to examples.
[0044]
Example 1
FIG. 1 is an explanatory view showing one example of a production process of a transparent conductive sheet for a transparent touch panel of the present invention. FIG. 2 is an enlarged sectional view of the transparent conductive sheet for a transparent touch panel of the present invention. FIG. 3 is a schematic sectional view of a liquid crystal display device incorporating a transparent touch panel.
[0045]
As an example of the optically isotropic substrate film (1), a film having a thickness of 100 μm obtained by casting a polycarbonate film was prepared. The retardation value was 4%, the visible light transmittance at 550 nm was 90%, and the glass transition point was 140 ° C.
[0046]
As the first mold film (S _1), a biaxially stretched polyethylene terephthalate film having a concave rough surface (d) was obtained by pressing the fine spherical convex portion of the range of particle size from 1 to 100 microns m by embossing Was prepared. A biaxially stretched polyethylene terephthalate film having a smooth surface was prepared as the second mold film (S ₂ ).
[0047]
The above-mentioned optically isotropic substrate film (1) and the first mold film (S ₁ ) are supplied to a pair of rolls arranged in parallel with a slight gap, and a non-solvent type is directed toward the gap between the rolls. A non-solvent type polyisocyanate compound ("Coronate HK" manufactured by Nippon Polyurethane Industry Co., Ltd.) in a weight ratio of 50: 3 to a silicone acrylate-based ultraviolet-curable resin ("C-E611" manufactured by NRC). While discharging the mixed resin liquid, the two rolls are rotated in a direction to bite each other, so that the ultraviolet-curable resin liquid is sandwiched between the optically isotropic base film (1) and the first mold film (S ₁ ). to so that, in a state where so sandwiched, output 120 W / cm, 1 lamp, lamp distance 150 mm, after performing ultraviolet ray irradiation to cure the resin solution under conditions of integrated quantity of light 850mJ / cm ² By heat treatment for 10 minutes at 140 ° C., it was without the active energy ray-curable resin layer having a thickness of 16 [mu] m (2a).
[0048]
Subsequently, the laminated film having the layer configuration of (1) / (2a) / (S ₁ ) and the second mold film (S ₂ ) obtained above were placed on a pair of rolls arranged in parallel with a slight gap. ), So that the same ultraviolet-curable resin liquid as described above is sandwiched between the optically isotropic substrate film (1) side of the laminated film and the second mold film (S ₂ ). In this state, the resin liquid was cured by irradiating ultraviolet rays under the same conditions as above, and then heat-treated at 140 ° C. for 10 minutes to form an active energy ray-curable resin layer (2b) having a thickness of 16 μm. .
[0049]
As a result, a laminated film having a layer configuration of (S ₂ ) / (2b) / (1) / (2a) / (S ₁ ) was obtained. The refractive index n ₁ of the optically isotropic substrate film (1) is 1.6, and the refractive index n ₂ of each of the active energy ray-curable resin cured product layers (2a) and (2b) is 1.43,
n ₂ <1.5 (i)
n ₁ −n ₂ > 0.1 (ii)
Conditions were both satisfied.
[0050]
In the case of a film having a layer structure of (2b) / (1) / (2a) obtained by peeling the mold films (S ₁ ) and (S ₂ ) from the laminated film, the active energy ray-curable resin layer (2a) side The fine concave rough surface (d) of the first mold film (S ₁ ) is transferred to the surface of the first mold film (S ₁ ), and the surface on the side of the active energy ray-curable resin layer (2a) has a convex rough surface having a fine hemispherical protrusion. Formed on the surface (p).
[0051]
Further, the film having the layer constitution of (2b) / (1) / (2a) had the following characteristics. The solvent resistance was evaluated by the change in appearance when the sample film was immersed in a solvent of each of acetone, methyl ethyl ketone, ethanol, isopropanol, toluene and cellosolve acetate at a temperature of 25 ° C. for 5 minutes. The heat deformation temperature by the heat sag method is as follows. A test piece having a width of 15 mm, a length of 30 mm and a thickness of 50 μm is used, and the test piece is projected 15 mm from an end of the table. Plot the amount of change (mm), which is the sag height at that time, on the axis, draw a curve, extend the tangent line at the rising inflection point of the curve to find the intersection with the level of change 0 mm, Temperature (° C.) is defined as the heat distortion temperature.
-Visible light transmittance at 550 nm: 89%
・ Haze (JIS K7105): 0.1%
・ Retardation value: 8nm
・ Surface hardness (JIS K5400, 100g load): 3H
Heat distortion temperature by heat sag method: 155 ° C
-Solvent resistance: No abnormalities-Heat shrinkage (130 ° C x 1 hour): MD direction 0.1%, TD direction 0.05%
[0052]
Next, the mold film (S ₂ ) was peeled off from the laminated film, and a 400 Å-thick transparent conductive layer (3) of ITO was formed on the exposed surface of the active energy ray-curable resin cured material layer (2b) by a sputtering method. (The adhesion of ITO was good), and the remaining mold film was peeled off. Thus, a transparent conductive sheet having a layer configuration of (2a) / (1) / (2b) / (3) was obtained.
[0053]
Separately, a transparent conductive sheet having a layer configuration of (2b) / (1) / (2b) / (3) was produced in the same manner as described above.
[0054]
The thus obtained transparent conductive sheet having the layer configuration of (2a) / (1) / (2b) / (3) and the layer configuration of (2b) / (1) / (2b) / (3) And a transparent conductive sheet having a dot spacer (DS) formed on the transparent conductive layer (3) surface of one of the two sheets in accordance with a conventional method. A transparent touch panel was produced with the conductive layer (3) side facing the other.
[0055]
The transparent touch panel thus obtained was assembled under the polarizing plate of the liquid crystal display element as shown in FIG. 3 to produce a liquid crystal display element, and its performance was evaluated. It was found that the visibility was improved by 30 to 40% and the light transmission amount was also significantly improved as compared with the touch panel. In addition, since the active energy ray-curable resin cured material layers (2a) and (2b) are provided, despite using a polycarbonate film as the optically isotropic substrate film (1), heat resistance, solvent resistance, The hardness, waist (rigidity), scratch resistance, adhesion of the transparent conductive layer, and moisture impermeability were good. In FIG. 2, (DS) is a dot spacer, (FP) is a polarizing plate, (B) is an electrode substrate of a liquid crystal cell, (LC) is a liquid crystal, and (AD) is an adhesive layer.
[0056]
Example 2
FIG. 4 is an enlarged sectional view showing another example of the transparent conductive sheet for a transparent touch panel of the present invention.
[0057]
As the first mold film (S ₁ ) and the second mold film (S ₂ ), a biaxially stretched polyethylene terephthalate film having a smooth surface was prepared.
[0058]
A non-solvent type silicone acrylate UV-curable resin (“C-E611” manufactured by RC Japan Co., Ltd.) is diluted with isopropanol, and then dispersed by spraying in a non-solvent. The liquid was cured. As a result , true spherical transparent spherical particles (b) having a particle size of 4 to 26 μm were obtained.
[0059]
The above-mentioned optically isotropic substrate film (1) and the first mold film (S ₁ ) are supplied to a pair of rolls arranged in parallel with a slight gap, and a non-solvent type is directed toward the gap between the rolls. A non-solvent type polyisocyanate compound ("Coronate HK" manufactured by Nippon Polyurethane Industry Co., Ltd.) in a weight ratio of 50: 3 to a silicone acrylate-based ultraviolet-curable resin ("C-E611" manufactured by NRC). While mixing, the resin liquid containing 20% by weight of the above spherical particles (b) is discharged, and both rolls are rotated in a direction to bite each other, so that the optically isotropic base film (1) and the first mold are rotated. as UV-curable resin liquid is sandwiched between the film (S _1), in a state where so sandwiched, output 120 W / cm, 1 lamp, lamp distance 150 mm, the accumulated amount 85 After performing the ultraviolet irradiation to cure the resin solution under the condition of mJ / cm ^2, by heat treatment for 10 minutes at 140 ° C., it was without the active energy ray-curable resin layer having a thickness of 12 [mu] m (2a).
[0060]
Subsequently, the laminated film having the layer configuration of (1) / (2a) / (S ₁ ) and the second mold film (S ₂ ) obtained above were placed on a pair of rolls arranged in parallel with a slight gap. ), So that the same ultraviolet-curable resin liquid as described above is sandwiched between the optically isotropic substrate film (1) side of the laminated film and the second mold film (S ₂ ). In this state, the resin liquid was cured by irradiating ultraviolet rays under the same conditions as described above, and then heat-treated at 140 ° C. for 10 minutes to form an active energy ray-curable resin layer (2b) having a thickness of 12 μm.
[0061]
As a result, a laminated film having a layer configuration of (S ₂ ) / (2b) / (1) / (2a) / (S ₁ ) was obtained. The refractive index n ₁ of the optically isotropic substrate film (1) is 1.6, and the refractive index n ₂ of each of the active energy ray-curable resin cured product layers (2a) and (2b) is 1.43,
n ₂ <1.5 (i)
n ₁ −n ₂ > 0.1 (ii)
Conditions were both satisfied. The refractive index of the spherical particles (b) was also 1.43.
[0062]
Thereafter, a transparent touch panel was produced in the same manner as in Example 1. As a result, a transparent conductive sheet for a transparent touch panel having the same good characteristics as in Example 1 was obtained.
[0063]
Examples 3 and 4
Instead of the silicone acrylate-based UV-curable resin, an epoxy acrylate-based UV-curable resin ("TUR1776HV" manufactured by Teikoku Chemical Industry Co., Ltd.) (Example 3), and a urethane acrylate-based UV-curable resin (manufactured by Mitsubishi Rayon Co., Ltd.) “FS-1296”) (Example 4) was used, but in each case, a transparent conductive sheet for a transparent touch panel having good characteristics according to Example 1 was obtained.
[0064]
【The invention's effect】
As mentioned in the section of the action, in the transparent transparent conductive sheet for a touch panel of the present invention, a fine hemispherical surface diameter from 1 to 100 microns m of one of the active energy ray curable resin cured layer (2a) The active energy ray-curable resin passes through the polarizing plate because it is formed on the convex rough surface (p) having a convex shape, and this surface is the surface on the incident light side when the touch panel is assembled. The incident light that has reached the convex rough surface (p) of the surface of the cured material layer (2a) enters the active energy ray-curable resin cured material layer (2a) without being reflected regardless of which direction it enters. Go.
[0065]
In addition, the refractive index n ₂ and the n ₂ of a refractive index n ₁ and the active energy ray curable resin cured layer of the optical isotropic substrate film (1) (2) <1.5 (i)
n ₁ −n ₂ > 0.1 (ii)
(I) further reduces the surface reflection of incident light, and (ii) cures the active energy ray-curable resin cured material layer (2) and the optically isotropic substrate film (1). The reflection at the interface with the surface becomes small.
[0066]
Therefore, the transparent touch panel using the transparent conductive sheet can be used to be superimposed below the polarizing plate of the liquid crystal display element, and the visibility and the light transmission amount are remarkably improved. Moreover, since the active energy ray-curable resin cured material layers (2a) and (2b) are provided on both sides of the optically isotropic substrate film (1), a film such as polycarbonate is used as the optically isotropic substrate film (1). In addition, they also have heat resistance, solvent resistance, hardness, stiffness (rigidity), scratch resistance, adhesiveness of the transparent conductive layer, and moisture impermeability.
[0067]
In addition, when the method of forming the active energy ray-curable resin cured product layer (2) using the mold film (S) ((S ₁ ) or (S ₂ )) is employed, the film thickness accuracy is improved and the active energy Such a trouble does not occur even if a linear curable resin liquid that absorbs moisture in the air and easily causes cloudiness, such as silicone acrylate, is used. Then, the formation of the convex rough surface (p) of the surface of one active energy ray-curable resin cured product layer (2a) is defined as an active energy ray-curable resin liquid within ± 0.05 of the refractive index of the cured product . even when done by using a resin solution obtained by blending a fine and transparent spherical particles of a particle size from 1 to 100 microns m (b) providing a very close refractive index, the active energy ray curable resin cured layer (2a) Is formed while the resin liquid is sandwiched between the optically isotropic substrate film (1) and the mold film (S), so that no force is applied in the direction of displacement, and therefore there is a possibility that a streak is formed as in the coating method. There is no.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an example of a production process of a transparent conductive sheet for a transparent touch panel of the present invention.
FIG. 2 is an enlarged sectional view of a transparent conductive sheet for a transparent touch panel of the present invention.
FIG. 3 is a schematic sectional view of a liquid crystal display device incorporating a transparent touch panel.
FIG. 4 is an enlarged sectional view showing another example of the transparent conductive sheet for a transparent touch panel of the present invention.
[Explanation of symbols]
(1)… optical isotropic substrate film,
(2), (2a), (2b) ... active energy ray-curable resin cured material layer,
(p) ... convex convex surface,
(b)… spherical particles,
(3) ... transparent conductive layer,
(S), (S ₁ ), (S ₂ )… mold film,
(d)… concave concave surface,
(DS) ... dot spacer
(FP)… Polarizing plate,
(B)… the electrode substrate of the liquid crystal cell,
(LC)… Liquid crystal,
(AD)… Adhesive layer

Claims (7)

A transparent conductive sheet for an optically isotropic transparent touch panel that is used under the polarizing plate of a liquid crystal display element.It is a non-solvent type active energy ray-cured on both sides of the optically isotropic substrate film (1) mold cured resin layer provided with a (2), convex rough surface surface of the one radiation-curable resin cured layer (2a) is having raised fine hemispherical diameter from 1 to 100 microns m (p A transparent conductive sheet for a transparent touch panel, wherein a transparent conductive layer (3) is further provided on the other active energy ray-curable resin cured material layer (2b). The optically isotropic substrate film (1) is a film obtained by a casting method, and has a retardation value of 15 nm or less, a visible light transmittance at 550 nm of 70% or more, and a glass transition point of 100 ° C. or more. The transparent conductive sheet for a transparent touch panel according to claim 1. When the refractive index of the optically isotropic substrate film (1) is n ₁ and the refractive index of the active energy ray-curable resin cured material layer (2) is n ₂ ,
n ₂ <1.5 (i)
n ₁ −n ₂ > 0.1 (ii)
2. The transparent conductive sheet for a transparent touch panel according to claim 1, wherein the following relationship is satisfied. 2. The transparent conductive sheet for a transparent touch panel according to claim 1, wherein the active energy ray-curable resin constituting the non-solvent type active energy ray-curable resin layer (2) is silicone acrylate, epoxy acrylate or urethane acrylate. The formation of the active energy ray-curable resin cured material layer (2) on the optically isotropic substrate film (1) is performed in parallel with a slight gap enough to sandwich the two films described below and the resin liquid described later. A pair of rolls arranged in the above are supplied with a photo-isotropic base film (1) and a mold film (S), and a non-solvent type active energy ray-curable resin liquid is discharged toward a gap between the rolls. By rotating both rolls in the direction of biting each other, the active energy ray-curable resin liquid was sandwiched between the optically isotropic base film (1) and the mold film (S), and the sandwich was performed as such. The transparent conductive sheet for a transparent touch panel according to claim 1, wherein the transparent conductive sheet is formed by irradiating active energy rays in the state to cure the resin liquid. Forming convex rough surface on the surface of one of the active energy ray curable resin cured layer (2a) (p) is, as a template film (S), the shape of pressed fine spheres having a particle size of from 1 to 100 microns m The transparent conductive sheet for a transparent touch panel according to claim 5, wherein the transparent conductive sheet is formed by using a film having a concave rough surface (d). The formation of the convex rough surface (p) on the surface of the active energy ray-curable resin cured material layer (2a) is very close to the active energy ray-curable resin liquid within ± 0.05 of the refractive index of the cured product. fine, transparent spherical particles (b) according to claim 5 the transparent conductive sheet for a transparent touch panel according in which was performed using a blended resin solution having a particle size of from 1 to 100 microns m giving the refractive index.

Images