JP3696661B2 - Transparent conductive sheet for inner touch panel - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a transparent conductive sheet for a light isotropic transparent touch panel (that is, for an inner touch panel) that is used under a polarizing plate of a liquid crystal display element.
[0002]
[Prior art]
Recently, transparent touch panels (touch keys, touch switches) that can be input simply by touching the display screen with a finger or pressing the display screen with a pen have become widespread. If a touch panel is placed on a display screen such as a cathode ray tube and pressed directly with a finger or a pen, input can be achieved. The position pressed by the finger or pen is recognized as XY coordinates and input to the computer. Computers can range from electronic notebooks and mobile phones to large electronic blackboards.
[0003]
The transparent conductive sheet used for the above transparent touch panel basically has a layer structure of a conductive layer (especially ITO layer) / polymer film. When used as a touch panel, two transparent conductive sheets are used. The conductive layer side of the conductive sheet is used so as to be opposed to each other through a spacer.
[0004]
In Japanese Patent Application Laid-Open No. Sho 62-115613, a conventional touch panel is formed by etching an ITO film surface of two transparent conductive films having an ITO thin film, with the upper and lower electrodes facing each other through a spacer. In the invention of the publication itself, a conductive film for a touch panel composed of a UV curable resin hard coat film / transparent plastic film / UV cured 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, or the like is used. In the examples, a polyester film is used.
[0005]
Japanese Patent Laid-Open No. 5-50561 discloses a conventional transparent touch panel in which a transparent conductive thin film is opposed to an entire or part of one surface of a transparent plastic film such as a polyester film. It is stated that it is produced by arranging via dot spacers. In the invention of the publication itself, a transparent conductive film is used in which one surface has a center line average roughness of 0.05 to 5.0 μm and a transparent conductive thin film is formed on the other surface. As the film, polyethylene terephthalate, polycarbonate, polyethersulfone, etc. can be used, but in the examples, an upper sheet in which an ITO thin film is formed on one side of a biaxially stretched polyethylene terephthalate film, and a biaxially stretched polyethylene terephthalate A transparent touch panel in which a coating agent containing fine particles is applied to one side of the film, dried, and the lower sheet on which the ITO thin film is formed on the other side is arranged via dots and spacers so that the ITO thin film faces each other is produced. .
[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 in the range of 0.05 to 5.0 μm. There is a transparent conductive film in which a transparent conductive thin film is formed on the surface. As the film, polyethylene terephthalate, polycarbonate, polyethersulfone, polystyrene, cellulose triacetate, etc. can be used. In the examples, a sheet having an ITO thin film formed on one side of a biaxially stretched polyethylene terephthalate film, A transparent touch panel in which a coating agent containing fine particles is applied to one side of an axially stretched polyethylene terephthalate film, dried, and a sheet on which the ITO thin film is formed is arranged via dots and spacers so that the ITO thin film faces each other Is making. A transparent coating in which a coating agent containing fine particles is applied to one side of a biaxially stretched polyethylene terephthalate film, dried, and sheets with an ITO thin film formed on the coated surface are arranged with dots and spacers so that the ITO thin film faces each other. There is also a disclosure about touch panels.
[0007]
Japanese Patent Application Laid-Open No. 62-131416 states that a polyester film / conductive layer laminate is known as a conventional laminated film for a touch switch. In the invention of the publication itself, the surface electrical resistance 10 ¹² Wear resistance layer B of Ω / □ or less, organic polymer film substrate A, and surface electrical resistance 3 × 10 ^Three A laminated film for a touch switch in which a transparent conductive layer C of Ω / □ or less is laminated in the order of B / A / C is used. 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. [] Is an optional layer. As the transparent insulating film, a biaxially stretched polyester film is used in the examples, but polyamide, polyethersulfone, polyarylate, polyolefin, cellulosic 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 (polyethersulfone, polyetheretherketone, polyester, polycarbonate, polyolefin, especially the first two). On the other hand, the transparent conductive layer 3 and the organic silicon polymer layer 2 subjected to the oxidation treatment are 1/2/3, 2/1/3, 2/1/2/3, 3/2/1/2. A gas barrier transparent conductive laminate laminated in the order of / 3 is shown. Since this laminate is a conductive film having transparency in the visible light region and a low gas permeability such as oxygen and water vapor, it is said to be suitable for application to liquid crystal display elements and the like.
[0010]
[Problems to be solved by the invention]
As described in the above-mentioned documents, the transparent touch panel basically includes two transparent conductive sheets having a layer configuration of “conductive layer (especially ITO layer) / polymer film”. It has a structure in which the conductive layer sides are arranged to face each other with a spacer so as to face each other.
[0011]
By the way, a normal transparent touch panel is used by being superimposed on the uppermost layer of the liquid crystal display element. Therefore, although attention should be paid to transparency, light isotropy cannot be considered. Therefore, as a polymer film, a polyester film (that is, a biaxially stretched polyethylene terephthalate film) that takes into account mechanical properties, surface smoothness, hardness, heat resistance, solvent resistance, scratch resistance, moisture permeability, cost, etc. Is usually used, and even if such a film having no optical isotropy is used as a base, no major problem occurs.
[0012]
However, when the transparent touch panel is used in such a manner that it is overlapped on the uppermost layer of the liquid crystal display element, it is inevitable that the reflection of light increases and the visibility becomes insufficient, and the recent advancement is made. It is no longer enough to meet the demand.
[0013]
Therefore, in order to improve the visibility, the use of a transparent touch panel under the polarizing plate of the liquid crystal display element has been studied, and this type of touch panel will be a promising next-generation or second-generation touch panel. Expected to be deaf. In this case, the base film of the transparent conductive sheet is required to have optical isotropy because of being incorporated under the polarizing plate, and is conventionally used as a polyester film (such as biaxially stretched polyethylene terephthalate). A film having no light isotropy cannot be used.
[0014]
The inventors of the present invention have been conducting research on a transparent touch panel installed under a polarizing plate of a liquid crystal display element. However, by using a conventionally known light isotropic film as a base film, the visibility is improved. It was not possible to produce a touch panel having the expected performance in terms of improvement in light resistance, 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 they are used by being superimposed on the uppermost layer of a liquid crystal display element. By forming it on a rough surface with a line average roughness in the range of 0.05 to 5.0 μm, it prevents color fringes and sticking, but reduces the amount of light transmitted due to reflection scattering on the surface. Tend. Moreover, in the Example, since formation of a rough surface is performed by the coating of the resin solution which mix | blended particle | grains, there also exists a disadvantage that the line | wire by a coater tends to be attached.
[0016]
In such a background, the present invention is a transparent conductive sheet for a light isotropic transparent touch panel (that is, for an inner touch panel) that is used under a polarizing plate of a liquid crystal display element. Even when resist formation, exposure, development, etching, and removal of the cured resist are performed on the layer, troubles such as fogging do not occur, visibility is good, and light transmission is large. An object of the present invention is to provide a transparent conductive sheet for an inner touch panel having properties such as heat resistance, solvent resistance, hardness, waist (rigidity), scratch resistance, and moisture permeability.
[0017]
[Means for Solving the Problems]
The transparent conductive sheet for an inner touch panel of the present invention is a transparent conductive sheet for a light isotropic transparent touch panel that is used under a polarizing plate of a liquid crystal display element, and is a light isotropic substrate film (1 ) On at least one side Formulated with a polyisocyanate compound having two or more free NCO groups Non-solvent type with acid and alkali resistance Polyisocyanate compound formulation An acrylic ester-based active energy ray-curable resin cured product layer (2) is provided, and at least one of the layers is provided. Polyisocyanate compound formulation Directly on the active energy ray-curable resin cured material layer (2) or Undercoat A transparent conductive layer (3) is provided through the layer.
[0018]
The present invention will be described in detail below.
[0019]
As the optically isotropic base film (1), films of polycarbonate, polyarylate, polyethersulfone, polysulfone, etc. are used.
[0020]
The photoisotropic substrate film (1) is preferably a film obtained by a casting method from the viewpoint of photoisotropy and adhesion to the active energy ray-curable resin cured material layer (2) described later. . The film exemplified above can be produced by an extrusion method, and such a film can also be used. Even if the film obtained by the extrusion method has optical isotropy, the acrylic ester-based active energy ray is used. Adhesiveness with the curable resin cured product layer (2) is inferior, so a process such as providing an anchor coating layer or corona discharge treatment in advance is required, which is industrially disadvantageous compared with a casting method film. . However, the present invention does not prohibit the provision of an anchor coating layer or corona discharge treatment on the optically isotropic substrate film (1).
[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. This is particularly desirable. When the retardation value exceeds 15 nm, the optical isotropy is lost to cause coloring and interference light, and the amount of reflected light increases, resulting in a decrease in image visibility. When the visible light transmittance is less than 70%, the brightness when used for a touch panel is insufficient. When the glass transition point is less than 100 ° C., heat resistance and dimensional stability are insufficient, and it becomes difficult to form a transparent conductive layer such as ITO, and even if it can be formed, its adhesion is insufficient. .
[0022]
The thickness of the optically isotropic substrate film (1) is not limited, but is usually 20 to 250 μm, and preferably 50 to 180 μm.
[0023]
As the active energy ray-curable resin constituting the non-solvent type active energy ray-curable resin cured product layer (2), in the present invention, non-solvent type acrylic ester-based active energy ray-curable resin having acid and alkali resistance is used. Resin is used. The cured layer of this resin has good adhesion to the optically isotropic substrate film (1), and is advantageous in terms of heat resistance, solvent resistance, hardness, waist (rigidity), and the like.
[0024]
And in the present invention, this The acrylic ester-based active energy ray-curable resin is blended with a polyisocyanate compound to form an acrylic ester-based active energy ray-curable resin cured material layer (2). Provide. The formation of a transparent conductive layer (3) is necessary to connect the upper and lower substrates of the touch panel, but an acrylic ester-based active energy ray-curable resin cured material layer (2 This is because the adhesion when forming the transparent conductive layer (3) from above the acrylic ester-based active energy ray-curable resin cured product layer (2) is improved.
[0025]
Here, various polyisocyanates such as hexamethylene diisocyanate, tolylene diisocyanate, and diphenylmethane diisocyanate are used as the polyisocyanate compound. The compounding amount of the polyisocyanate compound with respect to 100 parts by weight of the acrylic ester-based active energy ray-curable resin is usually 50 parts by weight or less, preferably 1 to 30 parts by weight, more preferably 3 to 25 parts by weight, especially 5 to 20 parts by weight. In this range, the adhesiveness of the transparent conductive layer (3) can be improved without impairing the properties of the acrylic ester-based active energy ray-curable resin cured product layer (2).
[0026]
Having acid and alkali resistance refers to various steps of resist formation, exposure, development, pattern formation by etching, and removal and removal of the cured resist film when the transparent conductive layer (3) is subsequently provided on the cured product layer (2). Means that no trouble such as cloudiness occurs. Even if a general active energy ray-curable resin is an acrylic resin, the acid-alkali resistance is often insufficient even though other properties are satisfied.
[0027]
above Polyisocyanate compound formulation The thickness of the acrylic ester-based active energy ray-curable resin cured product layer (2) is not particularly limited, but is usually 2 to 100 μm, particularly 3 to 50 μm.
[0028]
Non-solvent type on at least one side of the optically isotropic substrate film (1) Polyisocyanate compound formulation When the acrylic ester-based active energy ray-curable resin cured product layer (2) is provided, first, the optically isotropic base film (1) and the first mold film are placed on a pair of rolls arranged in parallel with a slight gap. (S1) and non-solvent type Polyisocyanate compound formulation While discharging the acrylic ester-based active energy ray-curable resin liquid and rotating both rolls in the direction of biting each other, active energy rays are generated between the optically isotropic substrate film (1) and the first mold film (S1). By curing the resin liquid by irradiating active energy rays (ultraviolet rays or electron beams) in such a state that the curable resin liquid is sandwiched Polyisocyanate compound formulation The acrylic ester-based active energy ray-curable resin cured product layer (2) is desirable. After the active energy ray irradiation, the curing can be completed by performing a heat treatment as necessary. As a result, optically isotropic substrate film (1) / Polyisocyanate compound formulation A laminated film having a layer structure of acrylic ester-based active energy ray-curable resin cured material layer (2) / first mold film (S1) is obtained.
[0029]
Non-solvent type on both sides of light isotropic substrate film (1) Polyisocyanate compound formulation When the acrylic ester-based active energy ray-curable resin cured product layer (2) is provided, the laminated film obtained above is placed on a pair of rolls arranged in parallel with a slight gap between the optically isotropic base film (1 ) Supply the second mold film (S2) with the side facing the inner surface side, rotate both rolls in the direction of biting each other, and the optically isotropic base film (1) side of the laminated film and the second Between the mold film (S2) Polyisocyanate compound formulation By allowing the acrylic ester-based active energy ray-curable resin liquid to be sandwiched, and irradiating active energy rays (ultraviolet rays and electron beams) in such a state to cure the resin liquid. Polyisocyanate compound formulation The acrylic ester-based active energy ray-curable resin cured product layer (2) is used. After the active energy ray irradiation, the curing can be completed by performing a heat treatment as necessary.
[0030]
As a result, a laminated film having a layer structure of (1) / (2) / (S1) or a laminated film having a layer structure of (S2) / (2) / (1) / (2) / (S1) is obtained. Therefore, the mold films (S1) and (S2) are peeled and removed at an appropriate stage after dripping.
[0031]
Here, as the mold film (S) ((S1), (S2)), a biaxially stretched polyester film, a biaxially stretched polypropylene film, or the like is preferably used. When these films are used as the mold film (S), they can be smoothly peeled off from the interface between (S) and (2) after the formation of the acrylic ester-based active energy ray-curable resin cured product layer (2).
[0032]
Also, using the mold film (S) like this Polyisocyanate compound formulation Adopting the method of forming the acrylic ester-based active energy ray-curable resin cured material layer (2) improves the film thickness accuracy, Polyisocyanate compound formulation Even if the acrylic ester-based active energy ray-curable resin liquid contains a substance that easily absorbs moisture in the air, such as a polyisocyanate compound, no trouble occurs. Therefore, by coating method Polyisocyanate compound formulation Compared with the case where the acrylic ester-based active energy ray-curable resin cured product layer (2) is formed, it is industrially more advantageous.
[0033]
In the present invention, as described above, the non-solvent type is provided on at least one side (preferably both sides) of the optically isotropic substrate film (1). Polyisocyanate compound formulation An acrylic ester-based active energy ray-curable resin cured product layer (2) is provided, but at least one of the layers is provided. Polyisocyanate compound formulation The surface of the acrylic ester-based active energy ray-curable resin cured product layer (2) can also be made smooth by using a smooth film as the mold film (S), and it has fine and smooth hemispherical bumps. It can also be formed on a convex rough surface.
[0034]
Formation of the latter convex rough surface can be achieved by using, as the mold film (S), a film having a concave rough surface obtained by pressing fine spherical convex portions by an embossing method. Moreover, the formation of the convex rough surface is Polyisocyanate compound formulation As an acrylic ester-based active energy ray-curable resin liquid, a fine and transparent spherical particle having a particle size of about 1 to 100 μm that gives a refractive index very close to that of the cured product (for example, a refractive index within ± 0.05 of the refractive index of the cured product). This can also be achieved by using a resin liquid in which (especially true spherical) particles are blended.
[0035]
After obtaining a laminated film having a layer structure of (1) / (2) / (S1) or (S2) / (2) / (1) / (2) / (S1) as described above Remove the mold film (S1), (S2) at an appropriate stage (in the latter case, (S) on one side may be left) Polyisocyanate compound formulation A transparent conductive layer (3) is formed on the acrylic ester-based active energy ray-curable resin cured product layer (2). Thereby, a transparent conductive sheet for a transparent touch panel having a layer structure of (1) / (2) / (3) or (2) / (1) / (2) / (3) is obtained.
[0036]
If necessary, an undercoat layer made of a metal oxide or the like can be formed prior to the formation of the transparent conductive layer (3). This is because the installation of the undercoat layer is positive for preventing curling and improving reliability in the patterning process and washing process of the transparent conductive layer (3). In addition, after the formation of the transparent conductive layer (3), an overcoat can be applied thereon if necessary.
[0037]
As the transparent conductive layer (3), ITO, InO ₂ , SnO ₂ , ZnO, Au, Ag, Pt, Pd, etc., and ITO is particularly important. The layer is formed by a sputtering method, a vacuum deposition method, an ion plating method, a sol-gel method, a coating method, or the like, and is particularly preferably formed by a sputtering method. The transparent conductive layer (3) can be a multilayer.
[0038]
Taking the case where ITO is used as an example, the thickness of the transparent conductive layer (3) is, for example, often 100 to 700 angstroms, particularly 150 to 600 angstroms. The surface resistance value of the sheet at this time is, for example, 100 to 1000Ω / □, preferably 200 to 600Ω / □.
[0039]
When producing a transparent touch panel, typically, the transparent conductive layer (3) side of the two transparent conductive sheets obtained as described above are opposed to each other, and about 0.02 to 1.0 mm, for example, between both sheets. It is sufficient to interpose a dot spacer (DS) having a thickness of.
[0040]
In this case, the transparent conductive layer (3) of one transparent conductive sheet is usually a full surface electrode, and the transparent conductive layer (3) of the other transparent conductive sheet is usually a patterned electrode. The transparent conductive sheet is formed by patterning by resist formation, exposure, development, and etching after the entire surface electrode is formed, and stripping and removing the cured resist. As the processing solution at this time, for example, a dilute aqueous solution of alkali such as sodium carbonate or potassium carbonate as a developing solution, an aqueous solution of ferric chloride or cupric chloride or an aqueous solution of an acid such as hydrochloric acid as an etching solution, or curing. As the resist stripping solution, an alkali stripping solution made of an aqueous solution having a concentration of 1 to 5% by weight such as sodium hydroxide or potassium hydroxide is used.
[0041]
The transparent touch panel thus produced is incorporated under the polarizing plate on the incident light side of the liquid crystal display element. If a transparent conductive sheet with a transparent conductive layer (3) formed on both sides as in (3) / (2) / (1) / (2) / (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 liquid crystal cell.
[0042]
[Action]
In the transparent conductive sheet for the inner touch panel of the present invention, the non-solvent type having acid and alkali resistance on at least one side of the optically isotropic substrate film (1). Polyisocyanate compound formulation An acrylic ester-based active energy ray-curable resin cured product layer (2) is provided.
[0043]
this Polyisocyanate compound formulation The acrylic ester-based active energy ray-curable resin cured product layer (2) has good adhesion to the optically isotropic substrate film (1) and has acid and alkali resistance, so the transparent conductive layer (3) Even if resist formation, exposure, development, pattern formation by etching, and removal and removal of the cured resist are performed, troubles such as fogging do not occur.
[0044]
Also Polyisocyanate compound formulation Due to the presence of the acrylic ester-based active energy ray-curable resin cured material layer (2), even if a film such as polycarbonate is used as the optically isotropic substrate film (1), heat resistance, solvent resistance, hardness, waist (rigidity) And it comes to have both scratch resistance and moisture permeability.
[0045]
Therefore, the transparent touch panel using the transparent conductive sheet of the present invention can be used by being superimposed under the polarizing plate of the liquid crystal display element, has good visibility, and has a large amount of light transmission. In addition, Polyisocyanate compound formulation The surface of the acrylic ester-based active energy ray-curable resin cured product layer (2) is formed into a convex rough surface with fine and smooth hemispherical ridges, and the surface is the surface on the incident light side when the touch panel is assembled Then, the incident light that has passed through the polarizing plate and reached the convex rough surface of the active energy ray-curable resin cured material layer (2) is not reflected from any direction. Polyisocyanate compound formulation Since it enters the acrylic ester-based active energy ray-curable resin cured product layer (2), visibility and light transmission are further improved.
[0046]
【Example】
The following examples further illustrate the invention.
[0047]
Example 1
FIG. 1 is an explanatory view showing an example of a manufacturing process of a transparent conductive sheet for an inner touch panel of the present invention. FIG. 2 is a schematic cross-sectional view of a liquid crystal display element incorporating an inner touch panel. 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.
[0048]
As an example of the optically isotropic base film (1), a film having a thickness of 100 μm obtained by casting a polycarbonate was prepared. The retardation value was 4%, the visible light transmittance at 90 nm was 90%, and the glass transition point was 140 ° C.
[0049]
A biaxially stretched polyethylene terephthalate film having a smooth surface was prepared as the first mold film (S1) and the second mold film (S2).
[0050]
The above-mentioned optically isotropic base film (1) and the first mold film (S1) are supplied to a pair of rolls arranged in parallel with a slight gap between them, and the 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.) and an acrylic ester UV curable resin (“Queen Beam-7008” manufactured by Nippon Zeon Co., Ltd.) at a weight ratio of 100: 10. The mixed resin liquid is discharged, and both rolls are rotated in the direction of biting each other, so that the ultraviolet curable resin liquid is sandwiched between the optically isotropic base film (1) and the first mold film (S1). In such a state, the output is 120 W / cm, one lamp, the lamp distance is 150 mm, and the integrated light quantity is 900 mJ / cm. ² The resin solution was cured by irradiating with ultraviolet rays under the conditions described above to obtain an active energy ray-curable resin layer (2) having a thickness of 10 μm.
[0051]
Subsequently, on a pair of rolls arranged in parallel with a slight gap, the laminated film having the layer structure of (1) / (2) / (S1) obtained above and the second mold film (S2) In the state where the same resin liquid is sandwiched between the optically isotropic substrate film (1) side of the laminated film and the second mold film (S2), The resin solution was cured by irradiating with ultraviolet rays under the same conditions as described above to obtain an active energy ray-curable resin layer (2) having a thickness of 10 μm. Finally, a heat treatment was performed at a temperature of 130 ° C. for 20 minutes to complete the curing.
[0052]
As a result, a laminated film having a layer structure of (S2) / (2) / (1) / (2) / (S1) was obtained. A film having a layer structure of (2) / (1) / (2) obtained by peeling and removing the mold films (S1) and (S2) from the laminated film had the following characteristics. The solvent resistance was evaluated by the change in appearance when the sample film was immersed in each solvent of acetone, methyl ethyl ketone, ethanol, isopropanol, toluene, and cellosolve acetate at a temperature of 25 ° C. for 15 minutes. The heat resistance was evaluated using the tan δ peak temperature obtained using a viscoelasticity measuring apparatus as an index.
-Visible light transmittance at 550 nm: 89%
・ Haze (JIS K7105): 0.1%
・ Retardation value: 8nm
・ Surface hardness (JIS K5400, 100g load): 3H
-Heat resistance (tan δ peak temperature by viscoelasticity measurement): 150 ° C
・ Solvent resistance: No abnormalities
Heat shrinkage rate (120 ° C x 1 hour): MD direction 0.1%, TD direction 0.05%
[0053]
Next, the mold film (S2) was peeled off from the laminated film and exposed. Polyisocyanate compound formulation Acrylic ester-based active energy ray-curable resin cured material layer (2) After forming a transparent conductive layer (3) with a thickness of 400 angstroms by ITO on one side of the surface (ITO adhesion was good) The remaining mold film (S1) was peeled and removed. As a result, a transparent conductive sheet having a layer structure of (2) / (1) / (2) / (3) was obtained. Prior to the formation of the transparent conductive layer (3), an undercoat layer made of a metal oxide can be formed.
[0054]
For one of the two transparent conductive sheets thus obtained, the transparent conductive layer (3) is patterned on the transparent conductive layer (3) by conventional methods, such as resist formation, exposure, development, etching, and removal of the cured resist. However, there was no trouble such as cloudiness.
[0055]
Next, using the transparent conductive sheet having the whole surface electrode obtained above and the transparent conductive sheet having the pattern electrode, the transparent conductive layer (3) of one of the two sheets is preliminarily formed on the surface of one of the two sheets according to a conventional method. After forming the dot spacer (DS), a transparent touch panel was prepared by making the transparent conductive layer (3) side of the two sheets face each other.
[0056]
The obtained transparent touch panel is incorporated under the polarizing plate of the liquid crystal display element as shown in FIG. 2 to produce a liquid crystal display element, and its performance is evaluated. As a result, the conventional touch panel in which the transparent touch panel is placed on the liquid crystal display element is used. In comparison, it was found that the visibility was greatly improved and the amount of light transmission was also improved.
[0057]
Example 2
Example 1 was repeated except that a biaxially stretched polyethylene terephthalate film having a concave rough surface obtained by pressing a fine spherical convex portion by an embossing method was used as the first mold film (S1). A film having a layer structure of / (1) / (2) was obtained. In this film, one side Polyisocyanate compound formulation The fine concave rough surface of the first mold film (S1) is transferred to the surface of the acrylic ester-based active energy ray-curable resin layer (2). Polyisocyanate compound formulation The surface on the acrylic ester-based active energy ray-curable resin layer (2) side was formed into a convex rough surface having fine and smooth hemispherical ridges.
[0058]
A transparent conductive sheet in which a transparent conductive layer (3) is provided on the smooth surface side of a film having a layer structure of (2) / (1) / (2) having one surface formed as a convex rough surface, and Example 1 A transparent touch panel was prepared using the transparent conductive sheet having the layer structure of (2) / (1) / (2) / (3) prepared in Example 1, and the performance superior to that of Example 1 was further improved. It was played.
[0059]
【The invention's effect】
In the transparent conductive sheet for the inner touch panel of the present invention, the non-solvent type having acid and alkali resistance on at least one side of the optically isotropic substrate film (1). Polyisocyanate compound formulation An acrylic ester-based active energy ray-curable resin cured product layer (2) is provided. this Polyisocyanate compound formulation The acrylic ester-based active energy ray-curable resin cured product layer (2) has good adhesion to the optically isotropic substrate film (1) and has acid and alkali resistance, so the transparent conductive layer (3) Even if resist formation, exposure, development, pattern formation by etching, and removal and removal of the cured resist are performed, troubles such as fogging do not occur.
[0060]
Also Polyisocyanate compound formulation Due to the presence of the acrylic ester-based active energy ray-curable resin cured material layer (2), even if a film such as polycarbonate is used as the optically isotropic substrate film (1), heat resistance, solvent resistance, hardness, waist (rigidity) And it comes to have both scratch resistance and moisture permeability.
[0061]
Therefore, the transparent touch panel using the transparent conductive sheet of the present invention can be used by being superimposed under the polarizing plate of the liquid crystal display element, has good visibility, and has a large amount of light transmission.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an example of a manufacturing process of a transparent conductive sheet for an inner touch panel of the present invention.
is there.
FIG. 2 is a schematic cross-sectional view of a liquid crystal display element incorporating an inner touch panel.
[Explanation of symbols]
(1)… light isotropic substrate film,
(2)… Polyisocyanate compound formulation Acrylic ester-based active energy ray-curable resin cured product layer,
(3) ... transparent conductive layer,
(S), (S1), (S2)… mold film,
(DS) ... dot spacer
(FP) ... Polarizing plate,
(B) ... electrode substrate of liquid crystal cell,
(LC) ... Liquid crystal,
(AD)… Adhesive layer

Claims (4)

A transparent conductive sheet for an optically isotropic transparent touch panel that is used under a polarizing plate of a liquid crystal display element, wherein at least one free NCO is provided on at least one surface of the optically isotropic substrate film (1). A non-solvent type polyisocyanate compound with an acid / alkali resistance compounded with a group-containing polyisocyanate compound and an acrylic ester-based active energy ray-curable resin cured material layer (2), and at least one polyisocyanate compound compound activity A transparent conductive sheet for an inner touch panel, wherein the transparent conductive layer (3) is provided directly or via an undercoat layer on the energy ray curable resin cured product layer (2).   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 inner touch panels according to claim 1. The formation of the polyisocyanate compound-containing acrylic ester-based active energy ray-curable resin cured material layer (2) on the optically isotropic substrate film (1) is applied to a pair of rolls arranged in parallel with a slight gap between them. The isotropic substrate film (1) and the mold film (S) are supplied, and the non-solvent type polyisocyanate compound-containing acrylic ester-based active energy ray-curable resin liquid is discharged toward the gap between the rolls. Rotate in the direction of biting into each other so that the polyisocyanate compound-containing acrylic ester-based active energy ray-curable resin liquid is sandwiched between the optically isotropic substrate film (1) and the mold film (S). 2. The inner tack according to claim 1, wherein the resin layer is cured by irradiating active energy rays while being sandwiched between the two. Transparent conductive sheet for a panel. Polyisocyanate compound-containing acrylic ester-based active energy ray-curable resin cured product layer (2) Thickness of 2-100μ m The transparent conductive sheet for an inner touch panel according to claim 1.

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