JP6179185B2 - Electrode film for touch panel, touch panel using the same, and image display device - Google Patents

Description

  The present invention relates to an electrode film for a touch panel, a touch panel using the same, and an image display device.

  Image display devices equipped with a touch panel function have been widely put into practical use in mobile phones, tablet terminals, personal computers, PDAs, electronic dictionaries, car navigation systems, music players, digital cameras, digital video cameras, portable game machines, and the like. As image display devices become smaller and lighter, their use is no longer limited to offices and indoors, but is also being used outdoors and while moving by car or train.

  Large-sized image display devices equipped with a touch panel such as an electronic blackboard having a touch panel function and a table-type touch panel display are also on the market. For example, a table-type display can be arranged to spread various materials and contents on the table surface display, and can be viewed by being surrounded by members participating in the conference, or the conference can be advanced while being operated by touch It is like that. In addition, a large-sized image display device capable of 3D image display is expected mainly in the medical field, education, and academic field.

  As the image display device with a large-screen touch panel function is expected to develop in the future, it is possible to obtain an image that is easy to see, has excellent responsiveness even in a large area, and is capable of multi-touch. A touch panel of the type is disclosed (Patent Document 1, Patent Document 2).

In Patent Document 1 and Patent Document 2, a polyethylene terephthalate film is used as a base film of a touch panel, and an electrode made of a mesh-like conductive fine wire is formed on one surface thereof. However, a commercially available polyethylene terephthalate film has a problem that rainbow spots are observed when the screen is observed through a polarizing filter such as sunglasses.

JP 2012-94115 A JP 2012-79238 A

  Even when the screen of the image display device is viewed through a polarizing filter such as sunglasses, the generation of rainbow spots is suppressed and the visibility is excellent. It is an object to provide a touch panel and an image display device.

The representative present invention is as follows.
Item 1.
An electrode film for a touch panel in which an electrode is formed on at least one surface of a polyester film,
The electrode has a mesh shape composed of a grid of conductive thin wires,
The retardation of the polyester film is an electrode film for a touch panel that is 3000 nm or more and 30000 nm or less.
Item 2.
Item 2. The electrode film for a touch panel according to Item 1, wherein the polyester film has a ratio (Re / Rth) of retardation (Re) to thickness direction retardation (Rth) of 0.2 or more.
Item 3.
The polyester film has a ratio (Re / Rth) of retardation (Re) to thickness direction retardation (Rth) of 1.0 or more and a degree of plane orientation (ΔP) of 0.12 or less. 2. The electrode film for a touch panel according to 2.
Item 4.
Item 4. The electrode film for a touch panel according to any one of Items 1 to 3, wherein the polyester film has a tear strength of 50 mN or more.
Item 5.
The touch panel using the electrode film for touchscreens in any one of claim | item 1-4.
Item 6.
(1) a white light source having a continuous emission spectrum;
(2) Image display cell,
(3) The image display apparatus which has a polarizing plate arrange | positioned at the visual recognition side from the said image display cell, and (4) The touch panel of claim | item 5 arrange | positioned at the visual recognition side from the said polarizing plate.

  According to the present invention, the touch panel has excellent visibility with reduced image quality typified by rainbow spots generated when viewing an image through a polarizing filter, and has excellent responsiveness even in a large area. An electrode film, a touch panel, and an image display device can be provided. In this document, “rainbow spot” is a concept including “color spot”, “color shift”, and “interference color”.

It is the figure which showed one example of the arrangement | sequence diagram of the electrode in an electrode layer.

As for the electrode film for touchscreens of this invention, the electrode is formed in the at least one surface of the polyester film.

(Polyester film)
In the present invention, a polyester film is used as the base film of the electrode film for a touch panel. The retardation of the polyester film is 3000 nm or more and 30000 nm or less from the viewpoint of reducing rainbow spots. The lower limit of retardation is preferably 4500 nm or more, more preferably 5000 nm or more, further preferably 6000 nm or more, still more preferably 8000 nm or more, and still more preferably 10,000 nm or more. On the other hand, the upper limit of retardation is not thin even if the retardation is increased further, and the thickness of the film tends to increase according to the height of the retardation. Although it is set to 30000 nm from the viewpoint that it may be contrary to the demand for the conversion, it may be set to a higher value. In this document, when simply described as “retardation”, it means in-plane retardation.

  Retardation is represented by the product of birefringence (ΔNxy) caused by light incident on the film surface (xy plane) and thickness (d). Therefore, a higher retardation is obtained as the value of ΔNxy increases. On the other hand, since the retardation becomes relatively smaller as the film becomes thinner, it is desirable that the value of ΔNxy is larger in order to maintain the retardation value above a certain level while reducing the thickness.

  The smaller the difference between in-plane retardation and thickness direction retardation, the more isotropic the birefringence effect due to the observation angle and the smaller the change in retardation due to the observation angle. It is done. In particular, large displays exceeding 20 inches (20 inches, 22 inches, 26 inches, 28 inches, 30 inches, 32 inches, 37 inches, 40 inches, 42 inches, etc.) such as electronic blackboards and table-type touch panel displays. In the case of 46 inches, 52 inches, 57 inches, 65 inches, 70 inches, etc.), there are many opportunities to observe the screen from an oblique direction. That is, in the case of a large display, even when the screen is viewed from the front, the edge of the screen is observed from an oblique direction. From such a viewpoint, the ratio (Re / Rth) of the retardation (Re) and the thickness direction retardation (Rth) of the polyester film is preferably 0.2 or more, more preferably 0.5 or more, and still more preferably 0. 0.7 or more, particularly preferably 1.0 or more, and particularly preferably 1.1 or more. In addition, thickness direction retardation means the average value of the retardation obtained by multiplying two birefringence (DELTA) Nxz and (DELTA) Nyz when it sees from a film thickness direction cross section by film thickness (d), respectively here.

  The maximum value of the Re / Rth ratio is 2.0 (that is, a complete uniaxial symmetry film), but the machine is in a direction orthogonal to the orientation main axis direction as it approaches 1.0 and a complete uniaxial symmetry film. In such a case, it is preferable to adjust so that the degree of surface orientation described later is a specific numerical value or less. The Re / Rth ratio is preferably higher from the viewpoint of thinning and improving the viewing angle characteristics, but the upper limit is not required to reach the maximum value of 2.0, preferably 1.9 or less, more preferably 1 .8 or less.

  Retardation can be measured according to a known method. Specifically, it can be determined by measuring the refractive index and thickness in the biaxial direction. Moreover, it can also obtain | require using the commercially available automatic birefringence measuring apparatus (For example, KOBRA-21ADH: Oji Scientific Instruments Co., Ltd. make).

  Plane orientation degree (ΔP) from the viewpoint of maintaining retardation and Re / Rth ratio for suppressing rainbow spots and maintaining mechanical strength (tear strength) that can withstand the production of industrial liquid crystal display devices. Is preferably 0.12 or less. In particular, when the Re / Rth ratio is 1.0 or more, the degree of plane orientation (ΔP) is preferably 0.12 or less. Here, the degree of plane orientation is the difference between the average value of the refractive index (Nx) in the longitudinal direction and the refractive index (Ny) in the width direction of the film, and the value of the refractive index (Nz) in the thickness direction, It can be represented by the following formula: ΔP = ((Nx + Ny) / 2) −Nz.

  The upper limit of the degree of plane orientation is more preferably 0.11 or less, still more preferably 0.102 or less, still more preferably 0.1 or less, still more preferably 0.098 or less, and much more. Preferably it is 0.095 or less, More preferably, it is 0.09 or less. On the other hand, the lower limit of the degree of plane orientation is preferably 0.04 or more, more preferably 0.05 or more, and still more preferably 0.06 or more.

  When the plane orientation degree is less than 0.04, the mechanical strength of the film is too low, which is not preferable in terms of workability. In addition, when the degree of plane orientation exceeds 0.12, it is difficult to achieve both retardation and mechanical strength under the thin film condition, and any one of the problems may occur.

  The thickness (d) of the polyester film is not particularly limited, but is preferably 500 μm or less, more preferably 300 μm or less, still more preferably 120 μm or less, and still more preferably 100 μm or less. The lower limit of the thickness of the polyester film is 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and further preferably 25 μm or more, from the viewpoint that it is difficult to maintain sufficient tear strength.

  Even if the polyester film is thin, it is preferable that the polyester film has a mechanical strength that can withstand handling in the manufacture of an industrial image display device. From this viewpoint, the polyester film preferably has a tear strength of 50 mN or more. Preferably, the tear strength is 100 mN or more, more preferably 130 mN or more. The tear strength of the film can be measured according to the method of JIS P-8116 as shown in the examples described later.

The polyester film includes, for example, inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, ultraviolet absorbers, light resistant agents, flame retardants, heat stabilizers, antioxidants. Further, an anti-gelling agent, a surfactant and the like can be added within a range that does not hinder the effects of the present invention and does not impair the transparency.

  A polyester film satisfying the physical properties as described above can be obtained by controlling stretching conditions and the like in general polyester film production conditions. A polyester film is generally produced by the following procedure. That is, the polyester resin is melted, and the non-oriented polyester extruded and formed into a sheet shape is stretched in the machine direction at a temperature equal to or higher than the glass transition temperature, and then stretched in the transverse direction by a tenter. Obtained by heat treatment. Stretching in the machine direction and the transverse direction can be performed separately for each direction, and by extending the clip width while guiding the tenter and changing the speed of the roll to stretch the machine direction and the transverse direction simultaneously. is there.

  In order to obtain a polyester film satisfying the above-described physical properties, it is preferable to perform simple uniaxial stretching. Furthermore, in order to reduce the degree of plane orientation while maintaining a high ratio (Re / Rth) of the retardation (Re) and thickness direction retardation (Rth) of the polyester film, the direction perpendicular to the stretching direction is simultaneously stretched in any direction. It is more preferable to perform a relaxation treatment. More specifically, using a facility generally called a simultaneous biaxial stretching machine, a longitudinal stretching and a transverse relaxation treatment, or a transverse stretching and a longitudinal relaxation treatment are performed, followed by heat treatment. A method can be exemplified. The order of stretching and relaxation treatment is preferably performed at the same time, but it may be performed in the order of relaxing after stretching or stretching after relaxing. A more preferable method is a method in which the stretching in the transverse direction and the relaxation treatment in the longitudinal direction are simultaneously performed. Although it is possible to relax during the heat treatment, it should be noted that heat wrinkles occur when the relaxation rate increases. It is also possible to produce using a sequential biaxial stretching machine. In that case, when relaxing in the longitudinal direction, the roll after stretching is slower than the roll before stretching while being heated by an external heater or the like, and then relaxed in the longitudinal direction and then guided to the tenter and stretched in the lateral direction. Can be implemented. Moreover, when relaxing in the lateral direction, it can be carried out by gradually narrowing the lateral clip width while heating in the tenter after performing longitudinal stretching by the method used in normal biaxial stretching. When a sequential biaxial stretching machine is used, the direction of uniaxial stretching is preferably stretching in the transverse direction. Although stretching in the machine direction is possible, it should be noted that there are problems such as the occurrence of minute scratches on the film surface and the occurrence of stretching unevenness during the longitudinal stretching. Furthermore, using the same principle as described above, the uniaxially stretched film can be subjected to a relaxation treatment with any one of a simultaneous biaxial stretching machine, a tenter, and a roll.

  The film forming conditions (particularly, stretching conditions) of the polyester film will be described more specifically. The stretching temperature is preferably 80 to 130 ° C, particularly preferably 90 to 120 ° C. The longitudinal draw ratio is preferably 1.0 to 3.5 times, particularly preferably 1.0 to 3.0 times. The transverse draw ratio is preferably 2.5 to 6.0 times, and particularly preferably 3.0 to 5.5 times.

When decreasing the plane orientation degree while keeping the ratio (Re / Rth) of the retardation (Re) and thickness direction retardation (Rth) of the polyester film high, the draw ratio is preferably 0.4 to 6 times, particularly preferably 0. .6 times to 5 times. It is preferable to set the stretching ratio in the direction perpendicular to the relaxation direction to be 3 to 6 times so that the stretching ratio in the relaxation direction is 0.4 to 0.97. Furthermore, it is more preferable that one direction is relaxed by 0.6 to 0.9 times and the film is stretched by 3.5 to 5.5 times in the direction perpendicular thereto. In particular, it is preferable that the film is stretched 3 to 6 times in the film width direction and simultaneously relaxed at a magnification of 0.4 to 0.97 in the film longitudinal direction.

  The magnification in the direction of relaxation and the direction of stretching can be arbitrarily set as long as it is within the above range, but uniaxiality increases as the stretching ratio increases, so that the degree of relaxation can be increased. preferable. On the other hand, when the draw ratio is lowered, if the effect is greatly relaxed, the effect of wrinkles cannot be ignored. Therefore, it is preferable to lower the relaxation rate.

  In order to control the retardation within the above range, it is preferable to control the ratio of the longitudinal draw ratio and the transverse draw ratio. If the difference between the vertical and horizontal draw ratios is too small, it is difficult to increase the retardation, which is not preferable. Moreover, if the magnification in the relaxing direction is too low, generation of wrinkles cannot be avoided, which is not preferable. Furthermore, if the magnification in the extending direction is too high, breakage tends to occur, which is not preferable. Setting the stretching temperature low is also a preferable measure for increasing the retardation. In the subsequent heat treatment, the treatment temperature is preferably from 100 to 250 ° C, particularly preferably from 160 to 245 ° C.

  The variation in retardation on the film is preferably small, and in order to suppress the variation, it is preferable to control the thickness variation of the film. Since the stretching temperature and the stretching ratio greatly affect the thickness variation of the film, it is preferable to optimize the film forming conditions from the viewpoint of suppressing the thickness variation. In particular, if the longitudinal stretching ratio is lowered to increase the retardation, the longitudinal thickness unevenness may be deteriorated. Since the vertical thickness unevenness may deteriorate in a specific range of the draw ratio, it is desirable to set the film forming conditions outside such a range.

  From the above viewpoint, the thickness unevenness of the polyester film is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less. It is particularly preferably 0% or less.

  In order to control the retardation of the polyester film within a specific range, the stretching ratio, stretching temperature, and film thickness can be appropriately set. For example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the higher the retardation. Conversely, the lower the stretching ratio, the higher the stretching temperature, and the thinner the film, the lower the retardation. However, when the thickness of the film is increased, the thickness direction retardation tends to increase. Therefore, it is desirable to set the film thickness appropriately within the range described below. In addition to the retardation control, final film forming conditions should be set in consideration of physical properties necessary for processing.

  The polyester resin for obtaining a polyester film satisfying the above physical properties may be any polyester resin used in the art. That is, it can be obtained by condensing an arbitrary dicarboxylic acid and a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and diphenylcarboxylic acid. Acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalate Acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, Dimer , It may be mentioned sebacic acid, suberic acid, dodecamethylene dicarboxylic acid.

  Examples of the diol include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3-propanediol, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone and the like can be mentioned.

  Each of the dicarboxylic acid component and the diol component constituting the polyester film may be used alone or in combination of two or more. Specific polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like, preferably polyethylene terephthalate and polyethylene naphthalate. In particular, since polyethylene naphthalate can increase ΔNxy, it is possible to reduce the film thickness while maintaining high retardation. The polyester resin may contain other copolymer components. From the viewpoint of mechanical strength, the proportion of the copolymer components is preferably 3 mol% or less, preferably 2 mol% or less, more preferably 1.5 mol% or less. .

(electrode)
A plurality of electrodes are provided on at least one surface of a polyester film as a substrate. The electrode has a mesh shape made of a grid of conductive thin wires. For example, a conventionally known electrode such as those described in JP 2012-94115 A or JP 2012-79238 A may be used. it can.

Although the said electrode may be laminated | stacked directly on the polyester film which is a base material, it can be laminated | stacked through an easily bonding layer and / or various other layers. Examples of the other layer include a hard coat layer, an index matching layer, and a low refractive index layer.

Since the electrode which comprises an electrode layer is a mesh electrode by a conductive fine wire, it is necessary to use a low resistance material and it is preferable to use a highly conductive metal or alloy. Examples of such metals include copper, silver, gold, platinum, palladium, nickel, tin, aluminum, cobalt, rhodium, iridium, iron, ruthenium, osmium, manganese, molybdenum, tungsten, niobium, tantel, titanium, and bismuth. , Antimony, lead and the like. Among these, copper, silver, gold, platinum, palladium, nickel, tin, aluminum, and alloys thereof are preferable in terms of excellent conductivity.
For the electrode formation with these metals or alloys, for example, the following forms A to C can be used.
A Use as metal foil or thin film.
To use as a thin film, first form a metal thin film on the base material by vacuum deposition, sputtering, ion plating, or by plating or bonding metal foil. To do. The thickness of the formed metal thin layer can be appropriately adjusted according to a desired resistance value, but is preferably 0.1 μm to 3 μm, and more preferably 0.2 μm to 1 μm. Next, the metal thin film is patterned to form a mesh electrode. When the mesh pattern is formed by photoetching, a photoresist film is formed on the metal thin film, exposed using a photomask, and developed with a developer to form a resist film mesh pattern. This is etched with an etching solution, and the resist film is peeled and removed to form a mesh pattern made of fine metal wires. Alternatively, when forming with a printing resist, a mesh pattern of the resist film is printed on the metal thin film by a method such as screen printing, gravure printing, inkjet, etc., and the resist film is etched except for the resist coating portion in the metal thin film with an etching solution. A fine metal mesh pattern is formed by peeling the film.

  The electrode may be provided with a coating layer. This coating layer is called a blackening layer. The blackened layer has a visual function that makes the metallic luster of the metal or alloy inconspicuous, and a function of improving durability by preventing rust and migration of the metal. The thickness of the blackening layer (coating layer) is preferably 5 μm or less, more preferably 3 μm or less, and particularly preferably 0.2 μm or more and 2 μm or less. Next, by removing the blackened layer on the visual recognition part that does not cover the electrode fine wires in the blackened layer (coating layer), an electrode having a mesh pattern excellent in visibility and durability can be formed. it can.

Examples of suitable methods for laminating the black part include plating and chemical etching. Any known so-called black plating may be used as the plating treatment, such as black ni plating, black Cr plating, black Sn-ni alloy plating, Sn-ni-Cu alloy plating, black zinc chromate treatment, etc. As mentioned. Specifically, black plating bath (trade name, Nikka Black, Sn-ni alloy system) manufactured by Nippon Chemical Industry Co., Ltd., black plating bath (trade name, Ebony-Chromium 85 series manufactured by Metal Chemical Industry Co., Ltd.) -Cr, Cr) and dip sole Co., Ltd. chromate agent (trade name, ZB-541, galvanized black chromate agent) can be used. The plating method may be either electroless plating or electrolytic plating, and may be mild or high-speed plating. Although the thickness is not limited as long as the plating thickness can be recognized as black, the normal plating thickness is preferably 1 μm to 5 μm.

  A black part can also be formed by oxidizing or sulfurating a part of the conductive metal part. For example, when the conductive metal part is copper, examples of the blackening treatment agent on the copper surface include: Meltex Co., Ltd., trade name Enplate MB438A, B, Mitsubishi Gas Chemical Co., Ltd., trade name: nPE- 900, manufactured by Mec Co., Ltd., trade name: Mec Etch Bond BO-7770V, manufactured by Isolate Chemical Laboratory, trade name: Copa-Black CuO, CuS, selenium-based Copa-Black no. 65 etc. can be used. In addition to the above, for example, it is possible to treat the sulfide to generate hydrogen sulfide (H 2 S) and to blacken the copper surface as copper sulfide (CuS). The thickness of the treatment is not limited as long as it can be recognized as black, but it is preferably 3 μm or less, more preferably 0.2 μm to 2 μm.

B is a method of printing a mesh pattern with an ink (or paste) containing conductive nanoparticles. In addition to the above metal fine particles, carbon may be used as the conductive nanoparticles. The conductive nanoparticles are preferably particles containing gold, silver, palladium, platinum, copper, carbon, or a mixture thereof. The average particle size of the nanoparticles is 2 μm or less, preferably 200 nm to 500 nm, and those having a particle size smaller than that of conventional micron particles are preferable for forming a mesh pattern. Screen printing or gravure printing is used for mesh pattern printing. The conductive material included in the ink (or paste) may be conductive fibers instead of metal particles. The conductive fiber includes a metal wire, a fibrous substance called nanowire, a hollow structure tube, and a nanotube. The average minor axis length of the metal nanowire (sometimes referred to as “average minor axis diameter” or “average diameter”) is preferably 100 nm or less, more preferably 1 nm to 50 nm, still more preferably 10 nm to 40 nm, and even more preferably 15 nm. -35 nm is particularly preferred. In the case of forming a conductive layer using conductive fibers, for example, JP2009-215594, JP2009-242880, JP2009-299162, JP2010-84173, JP2010-87105, JP2010. It can be formed by combining the techniques disclosed in -86714.

  When ink (or paste) containing conductive nanoparticles is used (B), the mesh pattern can be directly printed on the transparent substrate layer that also serves as the insulating layer.

C This is a method of using a silver halide photographic light-sensitive material used in photography, and subjecting this material to mesh pattern exposure, followed by development and fixing treatment to obtain a conductive fine line pattern with developed silver. The method for obtaining a conductive fine line pattern in the present invention includes the following three forms depending on the photosensitive material and the form of development processing.
(1) A mode in which a photosensitive silver halide black-and-white photosensitive material not containing physical development nuclei is chemically developed or thermally developed to form a metallic silver portion on the photosensitive material.
(2) An embodiment in which a photosensitive silver halide black-and-white photosensitive material containing physical development nuclei in a silver halide emulsion layer is dissolved and physically developed to form a metallic silver portion on the photosensitive material.
(3) A photosensitive silver halide black-and-white photosensitive material containing no physical development nuclei and an image receiving sheet having a non-photosensitive layer containing physical development nuclei are overlapped and developed by diffusion transfer, and the metallic silver portion is non-photosensitive image-receiving sheet. Form formed on top.

The aspect (1) is an integrated black-and-white development type, and a light-transmitting conductive film such as a light-transmitting conductive film is formed on the photosensitive material. The resulting developed silver is chemically developed silver or heat developed silver, and is highly active in the subsequent plating or physical development process in that it is a filament with a high specific surface.
In the above aspect (2), the light-transmitting conductive film such as a light-transmitting conductive film is formed on the photosensitive material by dissolving silver halide grains close to the physical development nucleus and depositing on the development nucleus in the exposed portion. A characteristic film is formed. This is also an integrated black-and-white development type. Although the development action is precipitation on the physical development nuclei, it is highly active, but developed silver is a sphere with a small specific surface.
In the above aspect (3), the silver halide grains are dissolved and diffused in the unexposed area and deposited on the development nuclei on the image receiving sheet, whereby a light transmitting conductive film or the like is formed on the image receiving sheet. A conductive film is formed. This is a so-called separate type in which the image receiving sheet is peeled off from the photosensitive material.

  In either embodiment, either negative development processing or reversal development processing can be selected (in the case of the diffusion transfer method, negative development processing is possible by using an auto-positive type photosensitive material as the photosensitive material). .

The chemical development, thermal development, dissolution physical development, and diffusion transfer development mentioned here have the same meanings as are commonly used in the industry, and are general textbooks of photographic chemistry such as Shinichi Kikuchi, “Photochemistry” (Kyoritsu Publishing) (Published in 1955), C.I. E. K. It is described in "The Theory of Photographic Processes, 4th ed." Edited by Mees (Mcmillan, 1977). Although this case is an invention related to liquid processing, a technique of applying a thermal development system as another development system can also be referred to. For example, the technique described in each specification of Unexamined-Japanese-Patent No. 2004-184893, 2004-334077, 2005-010752, 2004-085655 is applicable.
In addition, regarding the material and the conductive pattern manufacturing method used in the present invention, the description and technology of JP-A-2006-352073, which is an invention of a mesh-like electromagnetic wave shielding film, and Japanese Patent Application No. 2009, which is an invention of a capacitive touch panel -265467 and the technique described therein can be used.

Although a typical electrode layer is shown and demonstrated in FIG. 1, this invention is not limited to this. As shown in FIG. 1A, the electrode layer has a plurality of electrodes (r-1, r-2, r-3, r-4, r-5,..., Ri). The width rw of the electrode ri is preferably 2 mm or more and 8 mm or less, and more preferably 3 mm or more and 7 mm or less.

A lattice-like mesh structure which is a detailed structure of the electrode ri is shown in FIG. The electrode has a lattice-like mesh structure made of conductive thin wires. The mesh electrode can be formed in a polygon or indefinite shape other than the orthogonal lattice as shown in the figure, but a simple lattice is most preferable. An orthogonal lattice may be sufficient and a rhombus may be sufficient. The line width of the conductive thin wire rm is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 8 μm or less. The length of one side of the lattice constituting the mesh is preferably from 100 μm to 700 μm, and more preferably from 200 μm to 600 μm.

When the electrode film for a touch panel of the present invention is used as an upper electrode film of a capacitive touch panel, a large number of openings can be formed in the electrode by making the electrode ri mesh-shaped, and through this opening, Capable of electrostatic coupling between the touched finger and the lower electrode, improving responsiveness.

The non-conductive boundary region rd between the electrodes is formed by providing a disconnection portion in a continuous uniform mesh-like conductive thin wire, thereby forming a non-conductive boundary region rd and blocking conduction between adjacent electrodes. doing. The non-conductive boundary area between the electrodes is usually an elongated band in the prior art. The width of this band is a minute width that is difficult to be visually recognized. It may be perceived as irregularity with regularity due to a difference in light transmittance between the electrode portion and the non-conductive portion, a difference in reflectance, a difference in intrinsic color including gloss, and the like. For this reason, it is also preferable to dispose the isolated conductive fine wires in the non-conductive boundary region to make the distribution of the conductive fine wires in the plane uniform.

From the viewpoint of visibility, it is also preferable to change the width of the non-conductive boundary region randomly in the extending direction of the electrodes, that is, to form a band-like body having an irregular width and no linearity. The width rd (average value) of the belt-like body is preferably 15 μm or more and 350 μm or less from the viewpoint of interelectrode conduction and visibility.

  In response to an increase in the size of an image display device using a touch panel, an increase in the size of the touch panel itself is also required. In order to increase the size, it is necessary to reduce the parasitic capacitance between the electrodes as well as the resistance of the electrodes. Therefore, it is preferable to dispose dummy electrodes between the electrodes. FIG. 1A shows an example in which an original electrode (sensor electrode) and a dummy electrode are arranged. A dummy electrode is arranged across the sensor electrode. Both the sensor electrode and the dummy electrode are electrodes composed of fine mesh wires. The width of the dummy electrode is preferably 2 mm or less. The ET of the sensor electrode r-i represents a terminal for connection with the external control unit, and the dummy electrode is an isolated electrode group without connection with the external control unit. However, the dummy electrode may be grounded.

(Touch panel)

  The image display device may include a touch panel. The type and method of the touch panel are not particularly limited, and examples include a resistive touch panel and a capacitive touch panel. The touch panel usually has one or two or more electrode films regardless of the method. At least one of the electrode films preferably uses the electrode film for a touch panel of the present invention. As a usage form of the electrode film for a touch panel of the present invention, it can be used by a conventionally known method as an electrode film for a touch panel, but is particularly preferably used as an upper electrode film of a projected capacitive touch panel. When only one of the two electrode films uses the electrode film for a touch panel of the present invention, the base film of the other electrode film is another film or glass plate conventionally used as a base film for a touch panel. A rigid plate such as can be used.

  Examples of other films conventionally used as the base film include various resin films having transparency. For example, polyester resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth) acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, polyarylate A film obtained from one or more kinds of resins selected from the group consisting of resins and polyphenylene sulfide resins can be used. Among these, polyester resins, polycarbonate resins, and polyolefin resins are preferable, and polyester resins are preferable.

  When two polyester films of 3000 to 30000 nm are used as the base film of the electrode film, the orientation main axes of the polyester films are preferably close to each other. For example, the angle formed by the orientation axes of two polyester films is preferably 0 ° ± 30 °, preferably 0 ° ± 15 °, preferably 0 ° ± 10 °, preferably 0 ° ± 5 °, preferably It is 0 ° ± 3 °, preferably 0 ° ± 2 °, preferably 0 ° ± 1 °, preferably 0 °. When deviating from the substantially parallel relationship, the retardation difference between the two polyester films is preferably 1800 nm or more, preferably 2500 nm or more, preferably 3500 nm or more, preferably 4000 nm or more, preferably 5000 nm or more.

(Image display device)
The image display device typically includes (1) a white light source having a continuous emission spectrum, (2) an image display cell, (3) a polarizing plate disposed on the viewing side from the image display cell, and (4) A touch panel is provided on the viewing side of the polarizing plate. A liquid crystal cell or an organic EL cell is typically used as the image display cell. In this specification, it is assumed that the organic EL cell is obtained by integrating (1) a white light source having a continuous emission spectrum and (2) an image display cell.

  The image display device preferably includes a white light source having a continuous and broad emission spectrum from the viewpoint of suppressing rainbow spots. When the image display device includes a liquid crystal cell, the image display device preferably includes such a light source as a light source independent of the image display cell. On the other hand, in the case of an organic EL cell, since the organic EL cell itself has a function of a light source, it is preferable that the organic EL cell itself emits light having a continuous and broad emission spectrum. The method and structure of the light source having a continuous and broad emission spectrum are not particularly limited, and may be, for example, an edge light method or a direct type. “Continuous and broad emission spectrum” means an emission spectrum in which there is no wavelength region where the light intensity becomes zero in the wavelength region of at least 450 to 650 nm, preferably in the visible light region. The visible light region is, for example, a wavelength region of 400 to 760 nm, and may be 360 to 760 nm, 400 to 830 nm, or 360 to 830 nm.

  As a white light source having a continuous and broad emission spectrum, for example, a white light emitting diode (white LED) can be exemplified. White LEDs include phosphor-type LEDs (that is, elements that emit white light by combining a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor and a phosphor) and organic light emitting diodes (Organic light-emitting diodes). : OLED). A white light-emitting element that combines a blue light-emitting diode using a compound semiconductor with a yttrium, aluminum, and garnet-based yellow phosphor from the viewpoint of having a continuous and broad emission spectrum and excellent luminous efficiency. Light emitting diodes are preferred.

  As the liquid crystal cell, any liquid crystal cell that can be used in a liquid crystal display device can be appropriately selected and used, and the method and structure thereof are not particularly limited. For example, a liquid crystal cell such as a VA mode, an IPS mode, a TN mode, an STN mode, or a bend alignment (π type) can be appropriately selected and used. Therefore, the liquid crystal cell can be used by appropriately selecting a known liquid crystal material and a liquid crystal made of a liquid crystal material that can be developed in the future. In one embodiment, a preferred liquid crystal cell is a transmissive liquid crystal cell.

  As the organic EL cell, an organic EL cell known in the technical field can be appropriately selected and used. An organic EL cell is a light emitter (organic electroluminescence light emitter), and typically has a structure in which a transparent electrode, an organic light emitting layer, and a metal electrode are laminated in this order on a transparent substrate. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, and such A laminate of an electron injection layer composed of a light emitting layer and a perylene derivative or the like can be given. Thus, since an organic EL cell has a function as an image display cell and a function as a light source, when the image display device includes an organic EL cell, an independent light source is unnecessary. That is, the light source and the image display device in the image display device may be independent from each other or may be integrated as long as their functions are exhibited.

  A conventionally well-known polarizing plate can be used for the polarizing plate used for this invention. The polarizing plate has a structure in which both sides of a film-like polarizer are sandwiched between two protective films (sometimes referred to as “polarizer protective film”). As the polarizer, any polarizer (or polarizing film) used in the technical field can be appropriately selected and used. Representative polarizers include those obtained by dyeing a dichroic material such as iodine on a polyvinyl alcohol (PVA) film or the like, but are not limited to this, and are known and will be developed in the future. A polarizer to be obtained can be appropriately selected and used.

  The kind of polarizer protective film is arbitrary, and a film conventionally used as a protective film can be appropriately selected and used. From the viewpoint of handling and availability, for example, a triacetyl cellulose (TAC) film, an acrylic film, and a cyclic olefin-based film (for example, a norbornene-based film), a polypropylene film, and a polyolefin-based film (for example, TPX), It is preferable to use one or more films not having birefringence selected from the group consisting of polyester films and the like. Moreover, in one Embodiment, the optical compensation film which has an optical compensation function may be sufficient as the light source side protective film of a visual recognition side polarizer, and the visual recognition side protective film of a light source side polarizer. Since the optical compensation film is commercially available, they can be appropriately selected and used. For example, “Wideview-EA” and “Wideview-T” (made by Fujifilm) for TN system, “Wideview-B” (made by Fujifilm) for VA system, VA-TAC (Konica Minolta, Inc.) ), “ZEONOR FILM” (manufactured by ZEON CORPORATION), “ARTON” (manufactured by JSR), “X-plate” (manufactured by Nitto Denko), and “Z-TAC” (manufactured by FUJIFILM Corporation) for the IPS system ), “CIG” (manufactured by Nitto Denko Corporation), “P-TAC” (manufactured by Okura Kogyo Co., Ltd.), and the like.

  When an organic EL cell is used as the image display cell, the polarizing plate in the image display device is not essential. However, since the thickness of the organic light emitting layer is as thin as about 10 nm, external light is reflected by the metal electrode and emitted again to the viewing side. When viewed from the outside, the display surface of the organic EL display device looks like a mirror surface. May be visible. In order to shield such specular reflection of external light, it is preferable to provide a polarizing plate and a quarter-wave plate on the viewing side of the organic EL cell.

The touch panel of the present invention is preferably arranged on the viewing side with respect to the viewing side polarizing plate.

The angle formed by the orientation main axis of the electrode film for a touch panel and the polarization axis of the polarizer of the viewing side polarizing plate (assuming that the polyester film and the polarizer are in the same plane) is not particularly limited. From the viewpoint of reducing the temperature, it is preferably close to 45 degrees. For example, the angle is preferably 45 ° ± 25 ° or less, and preferably 45 ° ± 20 ° or less. In particular, from the viewpoint of reducing rainbow spots when the image display device is observed from an oblique direction through a polarizing film such as sunglasses, the angle is preferably 45 degrees ± 15 degrees or less, preferably 45 degrees ± 10 degrees or less, It is preferably 45 ° ± 5 ° or less, preferably 45 ° ± 3 ° or less, 45 ° ± 2 ° or less, 45 ° ± 1 ° or less, 45 °. In this document, the term “below” means that only the value following “±” is applied. That is, “45 degrees ± 15 degrees or less” means that a fluctuation in the range of 15 degrees above and below 45 degrees is allowed.

  Arranging the polyester film so as to satisfy the above conditions is, for example, a method of arranging the cut polyester film so that its orientation main axis is at a specific angle with the polarizer, or obliquely stretching the polyester film By doing so, it can be performed by a method of disposing it at a specific angle with respect to the polarizer.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and can be appropriately modified within a scope that fits the gist of the present invention. They are all included in the technical scope of the present invention.

(1) Retardation (Re)
Retardation is the direction of each axis when the thickness direction is the z-axis with respect to the film surface, and the two axis directions perpendicular to the z-axis and perpendicular to each other are the x-axis and the y-axis. Is a phase difference represented by the product of birefringence caused by the refractive index (Nx, Ny, Nz) and the film thickness d. Here, the longitudinal direction (MD) is the x axis and the width direction (TD) is the y axis, and the birefringence (ΔNxy) and thickness (d) generated by light incident on the polyester film surface (xy plane) The in-plane retardation which is the product was defined as retardation (Re). Accordingly, the birefringence (Δxy) and retardation (Re) were determined by the following formulas for each. Each refractive index was measured using an Abbe refractometer. The unit of retardation is nm.
ΔNxy = | Nx−Ny |
Re = ΔNxy × d

(2) Thickness direction retardation (Rth)
Thickness direction retardation indicates retardation generated by light incident from the thickness direction. Here, it calculated | required from following Formula as a product of the average of two birefringences of a xz plane and a yz plane, and film thickness (d). The unit is nm.
Rth = (| Nx−Nz | + | Ny−Nz |) / 2 × d

(3) Degree of plane orientation (ΔP)
Using the values of the refractive index (Nx) in the longitudinal direction, the refractive index (Ny) in the width direction, and the refractive index (Nz) in the thickness direction of the polyester film, the plane orientation degree (ΔP) was calculated according to the following formula.
ΔP = ((Nx + Ny) / 2) −Nz

(4) Erythema Evaluation An image display device provided with a touch panel having the following configuration was produced according to a conventional method, and a white filter was displayed on the viewing side surface by arranging a polarizing filter so as to be parallel to the viewing side surface. While maintaining the parallel state, while rotating the polarizing filter within a range of 360 ° with respect to the angle formed by the polarizing axis of the polarizing filter and the polarizing axis of the viewing side polarizer of the image display device, a white image is transmitted through the polarizing filter. The presence / absence and extent of rainbow spots were checked and evaluated according to the following criteria. ◎, ○, and △ are acceptable levels.
<Evaluation criteria>
A: There is no generation of rainbow spots from any direction.
○: No rainbow spots are observed from the vicinity of the front direction, and very thin rainbow spots may be observed when observed from an oblique direction.
(Triangle | delta): The erythema may not be observed from the front direction vicinity, but when observed from the diagonal direction, an erythema may be observed.
X: Iris can be clearly observed when observed from the front and oblique directions.
<Configuration of image display device>
(A) Backlight light source: White LED
(B) Image display cell: Liquid crystal cell (c) Polarizing plate: A polarizing plate in which a TAC film is used as a polarizer protective film for a polarizer composed of PVA and iodine.
(D) Touch panel: A touch panel using the electrode film for a touch panel obtained in each example described later as an upper electrode film (the lower electrode substrate is glass). The angle between the main orientation axis of the polyester film and the polarization axis of the polarizing plate was 45 °.

(5) Tear strength The tear strength of each polyester film was measured according to JIS P-8116 using an Elmendorf tear tester manufactured by Toyo Seiki Seisakusho. The tearing direction was performed so as to be parallel to the orientation main axis direction of the polyester film, and evaluation was performed according to the following criteria. The measurement in the orientation main axis direction was performed with a molecular orientation meter (MOA-6004 type molecular orientation meter, manufactured by Oji Scientific Instruments).
○: Tear strength is 50 mN or more ×: Tear strength is less than 50 mN

Below, the manufacturing method of polyester used in the Example is shown.
(Production Example 1-Polyester resin A)
When the temperature of the esterification reactor was raised to 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged and 0.017 parts by mass of antimony trioxide as a catalyst while stirring. 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine were charged. Next, the pressure was raised and the pressure esterification reaction was carried out under the conditions of gauge pressure 0.34 MPa and 240 ° C., then the esterification reaction can was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Furthermore, it heated up to 260 degreeC over 15 minutes, and 0.012 mass part of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was performed with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can and subjected to polycondensation reaction at 280 ° C. under reduced pressure.

  After completion of the polycondensation reaction, it is filtered through a NASRON filter with a 95% cut diameter of 5 μm, extruded into a strand from a nozzle, and cooled and solidified using cooling water that has been filtered (pore diameter: 1 μm or less) in advance. And cut into pellets. The obtained resin had an intrinsic viscosity of 0.62 dl / g and contained substantially no inert particles and internally precipitated particles. Hereinafter, the polyethylene terephthalate resin thus obtained is abbreviated as PET (A).

(Production Example 2—Adhesion Modified Coating Solution Adjustment)
Using a transesterification reaction and a polycondensation reaction by a conventional method, as a dicarboxylic acid component (based on the whole dicarboxylic acid component), 46 mol% of terephthalic acid, 46 mol% of isophthalic acid, and 8 mol% of sodium 5-sulfonatoisophthalate A water-dispersible sulfonic acid metal group-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as a glycol component (based on the entire glycol component) was prepared. Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, and 0.06 parts by mass of a nonionic surfactant were mixed. Then, the mixture was heated and stirred, and when the temperature reached 77 ° C., 5 parts by mass of the water-dispersible sulfonic acid metal base-containing copolymer polyester resin was added, and stirring was continued until the resin no longer solidified. Thereafter, the resin water dispersion was cooled to room temperature to obtain a uniform water dispersible copolyester resin liquid having a solid concentration of 5.0% by mass. Furthermore, after dispersing 3 parts by mass of aggregated silica particles (Silicia 310, manufactured by Fuji Silysia Co., Ltd.) in 50 parts by mass of water, 99.46 parts by mass of the water-dispersible copolyester resin liquid was mixed with 0.54 parts by mass of the aqueous dispersion was added, and 20 parts by mass of water was added with stirring to obtain an adhesive modified coating solution.

Example 1
PET (A) resin pellets containing no particles were dried by a conventional method, supplied to an extruder, and dissolved at 285 ° C. This polymer is filtered with a filter material of stainless sintered body (nominal filtration accuracy 10 μm particles 95% cut), extruded into a sheet form from the die, and then applied to a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. It was wound and solidified by cooling to make an unstretched film.

Next, the above-mentioned adhesive property-modified coating solution was applied on both sides of this unstretched PET film by a reverse roll method so that the coating amount after drying was 0.08 g / m ^2, and then dried at 80 ° C. for 20 seconds. did.

  The unstretched film on which this coating layer is formed is guided to a simultaneous biaxial stretching machine, and the end of the film is held by a clip while being guided to a hot air zone at a temperature of 90 ° C. so that the magnification is 0.8 times in the vertical direction It was relaxed and simultaneously stretched 4.0 times in the transverse direction. Next, it was treated at a temperature of 170 ° C. for 30 seconds and further subjected to a relaxation treatment of 3% in the width direction to obtain a polyester film 1 having a film thickness of about 50 μm.

Thereafter, the surface of the above-described polyester film 1 (A4 size) was neutralized and cleaned by air blowing. Next, a thin layer of metal copper having a thickness of 2 μm was provided on the surface of the polyester film 1 by an electrolytic plating method using an electrolytic copper sulfate plating bath. Next, a photoresist film is formed on the copper thin film formed as described above, a photomask is superimposed on the photoresist film, exposed, and developed with a developing solution, whereby the resist film mesh pattern in which the exposed portion is cured. Formed. This was etched with a ferric chloride etchant, and the cured resist film was peeled and removed to form a sensor electrode composed of conductive fine wires in a mesh pattern. The parameters of the pattern used as a photomask are as follows. In FIG. 1, the sensor electrode width rw is 4 mm, the dummy electrode width dpw is 1 mm, the electrode length and the dummy electrode length are 200 mm, and the sensor electrode mesh conductive thin wire The width of the mesh is 4 μm, the side length of the mesh lattice is 500 μm, the inclination angle of the fine mesh wire with the X axis is 45 °, and the width of the non-conductive boundary area (disconnection) between the sensor electrode and the dummy electrode is random and average The value is 30 μm (the maximum width of the boundary area is 45 μm, the minimum value is 15 μm, the ratio of the standard deviation of the width to the average value of the width is 0.35), and 20 electrodes are formed on an A4 size polyester film. It was a pattern to be formed.

(Example 2)
A polyester film 2 was obtained in the same manner as in Example 1 except that the thickness of the unstretched film was changed to about 58 μm and relaxed at a magnification of 0.9 times in the longitudinal direction. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Example 3)
By changing the thickness of the unstretched film, the thickness was about 38 μm, the thickness was relaxed at a magnification of 0.7 times, and the heat treatment was performed at a temperature of 180 ° C. for 30 seconds, as in Example 1. A polyester film 3 was obtained. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

Example 4
By changing the thickness of the unstretched film, the thickness was about 25 μm, the transverse stretch ratio was 5.0 times, and the polyester was treated in the same manner as in Example 1 except that it was heat-treated at 180 ° C. for 30 seconds. Film 4 was obtained. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Example 5)
By changing the thickness of the unstretched film, the thickness was about 80 μm, relaxed at a magnification of 0.85 times in the longitudinal direction, the stretching temperature was 95 ° C., and heat treatment was performed at a temperature of 180 ° C. for 30 seconds. Except for the above, a polyester film 5 was obtained in the same manner as in Example 1. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Example 6)
A polyester film 6 was obtained in the same manner as in Example 1 except that the thickness of the unstretched film was changed to about 38 μm and the thickness was relaxed by 0.6 times in the longitudinal direction. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Comparative Example 1)
The unstretched film produced by the same method as in Example 1 was guided to a tenter stretching machine, and the end of the film was guided with a clip while being guided to a hot air zone at a temperature of 125 ° C., and stretched 4.0 times in the width direction. . Next, while maintaining the width stretched in the width direction, the film was treated at a temperature of 225 ° C. for 30 seconds and further subjected to a relaxation treatment of 3% in the width direction to obtain a polyester film 7 having a film thickness of about 25 μm. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Comparative Example 2)
In the same manner as in Example 1, the polyester film 8 was stretched 3.6 times in the running direction and 4.0 times in the width direction, the heat setting temperature was 240 ° C., and a film thickness of about 38 μm was obtained. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Example 7)
In the same manner as in Comparative Example 1, the polyester film 9 having a film thickness of about 100 μm was obtained by stretching 4.0 times in the running direction and 1.0 times in the width direction. Due to the uniaxially stretched film, minute scratches were observed on the film surface. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Example 8)
A polyester film 10 was obtained in the same manner as in Example 1 except that the thickness of the unstretched film was changed to about 50 μm and the longitudinal relaxation treatment was not performed. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

Example 9
A polyester film 11 was obtained in the same manner as Example 3 except that the thickness of the unstretched film was changed to about 38 μm and the longitudinal relaxation treatment was not performed. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

(Comparative Example 3)
A polyester film 12 was obtained in the same manner as Example 4 except that the thickness of the unstretched film was changed to about 25 μm and the longitudinal relaxation treatment was not performed. Thereafter, in the same manner as in Example 1, an electrode composed of conductive fine wires having a mesh pattern was formed on the polyester film.

The physical properties of each polyester film and the results of rainbow spot evaluation are shown in Table 1 below. However, Example 7 shall be read as Reference Example 7.

As described above, when the polyester films 1 to 6 and 9 to 11 were used as the base film, it was confirmed that generation of rainbow spots was significantly suppressed and a liquid crystal display device having excellent visibility was obtained. In addition, the polyester films 1 to 6 and 9 to 11 are not only capable of providing an image display device with excellent visibility, but also have a sufficient tear strength despite being relatively thin. Therefore, it was confirmed that it was suitable for use in the manufacture of industrial image display devices. On the other hand, when the polyester films 7, 8, and 12 were used as substrate films, rainbow spots were produced when observed from the front, and good visibility could not be obtained. Although the polyester film 9 had no problem in visibility, the tear strength was insufficient. This is presumably because the polyester film 9 has a relatively high Re value and Re / Rth ratio but a high ΔP value. Since the polyester film 12 has a high ΔP value, the tear strength was insufficient.
If the screen must be observed from a considerably deep oblique direction on a large screen image display device such as an electronic blackboard or a table-type touch panel display, the result of rainbow mark evaluation is ◎, ○ level Is considered preferable.

  ADVANTAGE OF THE INVENTION According to this invention, provision of the electrode film for touch panels excellent in visibility, a touch panel, and an image display apparatus is attained. Therefore, the industrial applicability of the present invention is extremely high.

dp-i Indicates a dummy electrode number.
dpw Indicates the width of the dummy electrode.
ET electrode terminal rd Indicates the width of the nonconductive boundary region between the electrodes of the rd electrode.
The number of the ri electrode (sensor electrode) is shown.
rm Electrode mesh thin conductive wire is shown.
θ Indicates the angle formed by the electrode mesh fine line and the electrode arrangement direction.

Claims (6)

An electrode film for a touch panel in which an electrode is formed on at least one surface of a polyester film,
The electrode has a mesh shape composed of a grid of conductive thin wires,
Retardation of the polyester film state, and are more 30000nm less 3000 nm, is a surface orientation degree ([Delta] P) is 0.12 or less, the electrode film for a touch panel. The electrode film for a touch panel according to claim 1, wherein the polyester film has a ratio (Re / Rth) of retardation (Re) to thickness direction retardation (Rth) of 0.2 or more. The polyester film, the ratio between the retardation (Re) and the thickness direction retardation (Rth) (Re / Rth) is 1.0 or more, a touch panel electrode film according to claim 1 or 2. The electrode film for touchscreens in any one of Claims 1-3 whose tear strength of the said polyester film is 50 mN or more. The touch panel using the electrode film for touch panels in any one of Claims 1-4. (1) a white light source having a continuous emission spectrum;
(2) Image display cell,
(3) A polarizing plate disposed on the viewing side from the image display cell, and (4) an image display device having the touch panel according to claim 5 disposed on the viewing side from the polarizing plate.