JP5709311B2 - Transparent sheet and transparent touch panel - Google Patents

Description

  The present invention relates to a transparent sheet and a transparent touch panel.

  Conventionally, touch panels are used for display devices such as bank terminals (cash dispensers), ticket machines, personal computers, office automation equipment, electronic notebooks, PDAs, and mobile phones. The touch panel is a sensor that detects where the user touches without disturbing the screen display, and various methods have been devised and put into practical use. Usually, the touch panel and the display device are separate components, and two module components are combined (bonded) and used in a single case.

  As shown in Patent Document 1, a typical resistive film type touch panel has two transparent planar bodies each having a transparent electrode (transparent conductive film) such as ITO formed on one side of a transparent base film. It has a configuration in which transparent conductive films are arranged to face each other at regular intervals.

FIG. 13 is a cross-sectional view of the touch panel. The touch panel 100 includes an upper electrode film 110 and a lower electrode substrate 120, and a dot spacer 1 is interposed in the gap.
0 3 is entered. The upper electrode film 110 includes a retardation film 111 and an ITO electrode 112. The lower electrode substrate 120 includes a glass substrate 121 and ITO electrodes 1 2 2. Retardation film 111 and polarizing plate 101 are adhesive layer 1
It is pasted with 02. The glass substrate 121 and the retardation film 105 are bonded together with an adhesive layer 104.

  In the touch panel 100, the polarizing plate 101 and the retardation films 111 and 105 are used in combination in order to obtain a surface low reflection touch panel that suppresses reflection of external light and improves visibility (see, for example, Patent Document 2). .

  Conventionally, the retardation film 111 is formed of a polycarbonate, a cycloolefin polymer film, or the like.

JP 2000-89914 A Japanese Patent Laid-Open No. 10-48625

  However, a retardation film made of a material having a glass transition point (Tg) of 150 ° C. or lower, such as a polycarbonate or a cycloolefin polymer film, is formed by depositing ITO (indium tin oxide) on the film 111, for example, Tg = When the film temperature is set to 140 ° C. or higher, the retardation of the 150 ° C. film is lowered. Therefore, the film formation temperature and the heat treatment (annealing) temperature after the film formation cannot be increased, and the degree of crystallization of ITO is low. Can only be obtained. As a result, there is a problem that it is difficult to reduce the resistance of the ITO film.

  In addition, when the transparent conductive film is configured to have a predetermined pattern shape (for example, configured to be an aggregate of a plurality of strip-shaped conductive portions), the pattern shape of the transparent conductive film becomes conspicuous and is visually recognized. There was also a problem that the performance decreased. As one of the causes of this problem, it is conceivable that if the ITO is not sufficiently crystallized, the absorption of light having a wavelength of 400 to 450 nm is increased, and the ITO film has a strong yellowish color.

  Further, in order to make the pattern shape of the transparent conductive film inconspicuous, it is necessary to reduce the thickness of the transparent conductive film, but there is also a problem that the resistance value increases when the thickness of the transparent conductive film is reduced.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a transparent planar body and a transparent touch panel that can reduce resistance and improve visibility.

The object of the present invention is a transparent planar body having a transparent conductive film patterned on one side of a transparent substrate, comprising a polarizing plate on the other side of the transparent substrate, Retardation 100 nm ~ comprising an addition (co) polymer of a cyclic olefin having a copolymerization ratio of norbornene and ethylene of 80:20 to 90:10 and MVR (melt volume rate) of 0.8 to 2.0 cm3 / 10 min. It is a 150 nm retardation film, and is achieved by a transparent sheet having a shrinkage ratio of 30% by heat treatment at 160 ° C. for both MD (flow direction) and TD (vertical direction) of 0.5% or less .

  Moreover, an undercoat layer is interposed between the transparent substrate and the transparent conductive film, and the undercoat layer is composed of a laminate of two or more layers having different optical refractive indexes, and is provided on the low refractive index layer side. It is preferable that the transparent conductive film is formed.

  The low refractive index layer is made of silicon oxide, and the high refractive index layer is made of a resin material containing metal oxide particles having an optical refractive index of 2.0 to 2.8. preferable.

  Moreover, the said objective of this invention is a transparent touch panel provided with at least one above-mentioned transparent planar body, Comprising: The transparent conductive film of the said transparent planar body, and the 2nd transparent conductive film different from this transparent conductive film Is achieved by the transparent touch panels arranged in the opposite directions or in the same direction.

  According to the present invention, it is possible to provide a transparent planar body and a transparent touch panel capable of reducing resistance and improving visibility.

It is a schematic sectional drawing of the transparent touch panel which concerns on one Embodiment of this invention. It is a top view which shows a part of transparent touch panel shown in FIG. It is a top view which shows a part of other transparent touch panel shown in FIG. It is a top view which shows a part of modification of the transparent touch panel shown in FIG. It is a top view which shows another part of the modification of the transparent touch panel shown in FIG. FIG. 4 is a diagram showing measurement results of the crystallinity of the ITO film obtained in Example 1. It is a figure which shows the measurement result of the crystallinity degree of the ITO film | membrane obtained in Example 2. FIG. It is a figure which shows the measurement result of the crystallinity degree of the ITO film | membrane obtained in Example 3. FIG. It is a schematic sectional drawing which shows the modification of the transparent touch panel shown in FIG. It is a schematic sectional drawing which shows the other modification of the transparent touch panel shown in FIG. It is a schematic sectional drawing of the transparent planar body sample used for the sensory test. It is a graph which shows the result of the change confirmation experiment of the retardation value at the time of performing heat processing (annealing process) with respect to a transparent substrate. It is a schematic sectional drawing of the conventional touch panel.

  Hereinafter, actual forms of the present invention will be described with reference to the accompanying drawings. Each drawing is partially enlarged or reduced to facilitate understanding of the configuration, not the actual size ratio.

  FIG. 1 is a schematic cross-sectional view of a transparent touch panel according to an embodiment of the present invention. The transparent touch panel 100 is a capacitive touch panel and includes a first transparent planar body 1 and a second transparent planar body 2. The first transparent planar body 1 includes a transparent substrate 12 having a transparent conductive film 11 patterned on one surface side, and a polarizing plate 13 disposed on the other surface side of the transparent substrate 12. The polarizing plate 13 is usually attached to the transparent substrate 12 via a general transparent adhesive such as epoxy or acrylic (not shown). The 2nd transparent planar body 2 is provided with the transparent substrate 22 with which the transparent conductive film 21 patterned by the one surface side was formed. The first transparent planar body 1 and the second transparent planar body 2 are attached via the adhesive layer 3 so that the transparent conductive films 11 and 21 are opposed to each other. . In addition, you may arrange | position so that each transparent conductive film 11 and 21 may face the same direction.

  The touch panel 100 having such a configuration is used by being attached to a display device such as a bank terminal (cash dispenser), a ticket vending machine, a personal computer, an OA device, an electronic notebook, a PDA, or a mobile phone. When the touch panel 100 is attached, the touch panel 100 is attached to the display device via a transparent adhesive layer so that the polarizing plate 13 side becomes an exposed surface (touch surface).

Transparent substrate 12, 22, the copolymerization ratio of norbornene and ethylene is 80: 20~90: 10, MVR (melt volume rate) is 0.8 to 2.0 ^3/10 min, a glass transition temperature of 170 It is formed by a retardation film having a retardation of 100 nm to 150 nm made of an addition (co) polymer (cyclic olefin copolymer: COC) of a cyclic olefin at ˜200 ° C. In addition, each transparent substrate 12 and 22 which is a phase difference film is arrange | positioned so that each slow axis may become an angle orthogonal.

As the cyclic olefin copolymer (COC) which is an addition copolymer of norbornene and ethylene, for example, a commercially available product can be used. As a commercial item, the product name "TOPAS" by TOPAS Advanced Polymers (TAP) company etc. can be mentioned. The copolymerization ratio of norbornene and ethylene is preferably 80:20 to 90:10 by mass ratio. By setting it as such a copolymerization ratio, the addition copolymer of the cyclic olefin whose glass transition temperature (Tg) is 170-200 degreeC can be obtained. When the norbornene ratio is set to less than 80% by mass, a high glass transition temperature of 170 ° C. or higher cannot be obtained as shown in Table 1. Moreover, when the ratio of ethylene is set to less than 10% by mass, the strength of the obtained film is lowered, and it is difficult to endure necessary post-processing steps (coating step, thin film forming step, etc.). Here, the glass transition temperature (Tg) is a value measured by a differential scanning calorimeter (DSC-60 manufactured by Shimadzu Corporation) in accordance with JIS K7121.

Further, the cyclic olefin copolymer (COC), MVR is 0.7 cm ^3/10 min, 1.8 cm ^3/10 min, 1.9 cm ^3/10 min, 2.2 cm ^3/10 min, the four types of resins After using and pelletizing, the workability at the time of forming into a film was evaluated. As a result, as shown in Table 2, by way of MVR = 0.7cm ^3/10 min, processing the pelletizing and film interpolymer is difficult. Moreover, in the thing of MVR = 2.2cm < ³ > / 10min, the intensity | strength of the film obtained was low and film formation was difficult. In contrast, those of MVR = 1.8cm ^3/10 min and MVR = 1.9cm ^3/10 min, it was excellent in both workability pelletizing and film reduction. Thus, the MVR of the cyclic olefin copolymer is an addition copolymer of norbornene and ethylene (COC), is preferably from 0.8 to 2.0 ^3/10 min, further, 1.5～2.0Cm it is preferably ^3/10 min. In addition, MVR can be adjusted, for example by heat quantity adjustment at the time of copolymerization.

Here, the phenomenon in which light incident on an anisotropic material is separated into two lights (ordinary ray and extraordinary ray) having vibration directions perpendicular to each other is called birefringence. Retardation is ordinary ray and extraordinary ray. Phase difference (also called phase delay). In the present invention, when the refractive index in the MD direction (flow direction) in the film plane is nx, the refractive index in the TD direction (vertical direction) is ny, and the film thickness is d, the retardation (Re) is the MD direction. The difference (Δn) between the refractive index (nx) and the refractive index (ny) in the TD direction and the thickness (d) of the film is expressed by the equation (1). For example, an automatic birefringence meter KOBRA manufactured by Oji Scientific Instruments
It can be measured with 21-ADH. Although the retardation is controlled by stretching the copolymer film of norbornene and ethylene, the stretching technique is not particularly limited. The stronger the external stress, the greater the birefringence and the greater the retardation.
Re = Δnd = | nx−ny | × d (1)

Moreover, it is preferable that the shrinkage rate by heat treatment at 160 ° C. for 30 minutes is 0.5% or less for both MD (flow direction) and TD (vertical direction). If the shrinkage rate exceeds 0.5%, for example, when sputtering is performed at a high temperature such as 150 ° C. to form a highly crystalline transparent conductive film (ITO film), the flatness of the film cannot be maintained and the film is deformed. In addition, there is a problem that cracks occur in the ITO film formed on the surface. The means for suppressing the shrinkage ratio to 0.5% or less is not particularly limited, but the copolymerization ratio of norbornene and ethylene is 80:20 to 90:10, and MVR (melt volume rate) is 0.8 to 2. 0 cm ³ /
The cyclic olefin addition (co) polymer having a glass transition temperature of 170 to 200 ° C., which is 10 minutes, is used, for example, by stretching at 180 ° C. or higher.

  The materials of the transparent conductive films 11 and 21 include indium tin oxide (ITO), indium oxide, antimony-added tin oxide, fluorine-added tin oxide, aluminum-added zinc oxide, potassium-added zinc oxide, silicon-added zinc oxide, and zinc oxide. -Transparent conductive materials such as tin oxide, indium oxide-tin oxide, zinc oxide-indium oxide-magnesium oxide, zinc oxide and tin oxide, or metal materials such as tin, copper, aluminum, nickel and chromium, metals An oxide material can be exemplified, and two or more of these may be formed in combination. In addition, a simple metal weak against acid or alkali can be used as a conductive material.

  Further, a transparent conductive film 11, a composite material in which ultrafine conductive carbon fibers such as carbon nanotubes, carbon nanohorns, carbon nanowires, carbon nanofibers, and graphite fibrils, or ultrafine conductive fibers made of silver are dispersed in a polymer material that functions as a binder. It can also be used as 21 materials. Here, a conductive polymer such as polyaniline, polypyrrole, polyacetylene, polythiophene, polyphenylene vinylene, polyphenylene sulfide, poly p-phenylene, polyheterocyclic vinylene, PEDOT: poly (3,4-ethylenedioxythiophene) should be adopted as the polymer material. Can do. Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetheretherketone (PEEK), polycarbonate (PC), polypropylene (PP), polyamide (PA), polyacrylic (PAC) ), Non-conductive polymers such as polyimide, epoxy resin, phenol resin, aliphatic cyclic polyolefin, norbornene-based thermoplastic transparent resin can be employed.

  When a carbon nanotube composite material in which carbon nanotubes are dispersed in a non-conductive polymer material is employed as the material of the transparent conductive films 11 and 21, the carbon nanotubes generally have a diameter of 0.8 nm to 1.4 nm ( Since it is extremely thin (around 1 nm), it is possible to prevent the carbon nanotubes from obstructing light transmission by dispersing them one by one or in bundles in the non-conductive polymer material, thereby ensuring the transparency of the transparent conductive films 11 and 21. Is preferable.

  Examples of methods for forming the transparent conductive films 11 and 21 include PVD methods such as sputtering, vacuum deposition, and ion plating, CVD, coating, and printing. Specifically, a transparent conductive film is formed on a transparent substrate (retardation film) having the above characteristics by sputtering or the like while keeping the temperature of the substrate at 140 ° C. or higher. Alternatively, on the transparent substrate (retardation film) having the above characteristics, a transparent conductive film is formed by sputtering or the like while maintaining the temperature of the film at −10 ° C. to 150 ° C., and then heat-treated at a temperature of 140 to 180 ° C. Can be formed. Regarding the thickness, for example, when an ITO film is formed by sputtering, the thickness of the transparent conductive films 11 and 21 is preferably 60 nm or less, and more preferably 30 nm or less. Note that when the film thickness is 5 nm or less, it is difficult to form a continuous film, and it is difficult to form a stable conductive layer.

  As shown in FIGS. 2 and 3, the transparent conductive films 11 and 21 are each formed as an aggregate of a plurality of strip-shaped conductive portions 11 a and 21 a extending in parallel, and the strip-shaped conductive portions of the transparent conductive films 11 and 21 are formed. 11a and 21a are arrange | positioned so that it may mutually orthogonally cross. The transparent conductive films 11 and 21 are connected to an external drive circuit (not shown) through a routing circuit (not shown) made of conductive ink or the like. The pattern shape of the transparent conductive films 11 and 21 is not limited to that of the present embodiment, and may be any shape as long as a contact point such as a finger can be detected. For example, as shown in FIGS. 4 and 5, the transparent conductive films 11 and 21 have a configuration in which a plurality of rhombus-shaped conductive portions 11 b and 21 b are linearly connected, and the rhombus-shaped conductivity in each of the transparent conductive films 11 and 21. The connecting directions of the portions 11b and 21b may be orthogonal to each other and arranged so that the upper and lower rhombus-shaped conductive portions 11b and 21b do not overlap in plan view. As for the operation performance such as the resolution of the transparent touch panel 100, a configuration is adopted in which when the first transparent planar body 1 and the second transparent planar body 2 are overlapped, the area where no conductive portion is present is reduced. Is better. From such a viewpoint, the pattern shape of the transparent conductive films 11 and 21 is preferably a configuration in which a plurality of rhombus-shaped conductive portions 11b and 21b are connected in a straight line rather than a rectangular configuration.

  Patterning of the transparent conductive films 11 and 21 is performed by forming a mask portion having a desired pattern shape on the surface of the transparent conductive films 11 and 21 formed on the silicon-containing layer or the transparent substrate, respectively, and removing the exposed portion with an acid solution. Etching and removal can be performed by dissolving the mask portion with an alkaline solution or the like.

  The polarizing plate 13 is configured, for example, by stacking a cellulose triacetate layer (TAC layer) as a protective layer on both sides of a layer obtained by stretching polyvinyl alcohol (PVA) and staining with iodine as a polarizer. As long as the transmittance in the transmission axis direction is high and the transmittance in the absorption axis direction is low, a hydrophilic polymer film other than PVA, a dichroic dye other than iodine, and a transparent film material other than TAC are used. The polarizing plate 13 may be configured. Such a polarizing plate 13 is bonded so that the transmission axis and the slow axis of the transparent substrate 12 which is a retardation film form an angle of 45 degrees. Moreover, in order to protect the exposed surface of the polarizing plate 13, as shown in FIG. 1, you may comprise so that the coating layer 4 may be provided on the said exposed surface. The coating layer 4 is preferably made of a highly transparent material, specifically, polyethylene terephthalate (PET), polyimide (PI), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherether. Ketone (PEEK), polycarbonate (PC), polypropylene (PP), polyamide (PA), polyacryl (PAC), acrylic, amorphous polyolefin resin, cyclic polyolefin resin, aliphatic cyclic polyolefin, norbornene thermoplastic Examples thereof include a flexible film such as a transparent resin, a laminate of two or more of these, and glass. The exposed surface of the polarizing plate 13 or the coating layer 4 may be subjected to a surface treatment for improving scratch resistance, abrasion resistance, fingerprint resistance, antireflection, and non-glare properties. In addition, the coating layer is usually attached to the polarizing plate 13 via a general transparent adhesive such as epoxy or acrylic (not shown).

  The adhesive layer 3 may be made of a general transparent adhesive such as epoxy or acrylic, and may include a core made of a norbornene resin transparent film. Further, the adhesive layer 3 may be formed by overlapping a plurality of sheet-like adhesive materials, and further, a plurality of types of sheet-like adhesive materials may be overlapped. The thickness of the pressure-sensitive adhesive layer 3 is not particularly specified, but is practically preferably 200 μm or less. Moreover, 1.40-1.70 are preferable and, as for the optical refractive index of the adhesion layer 3, it is still more preferable that it is 1.46-1.57. When the refractive index of the adhesive layer is made close to (higher) the refractive index of the transparent conductive film, the difference in refractive index at the interface is reduced, and the effect of making the pattern shape inconspicuous increases, but the refractive index of the adhesive layer 3 is increased. Requires the addition of fine particles of high refractive material, and there is a problem that the transmittance as a transparent sheet is lowered. Moreover, the adhesion layer 3 is in contact with the transparent conductive film, and it is not preferable to include a material that damages the transparent conductive film such as an acid.

Here, the copolymer of norbornene and ethylene, which is the material of the transparent substrates 12 and 22 according to the present invention, has a water absorption rate (23 ° C./24 hours) of usually about 0.005 to 0.1%. Preferably there is. If the water absorption rate (ISO 62 compliant, 23 ° C./24 hours) exceeds 0.1%, the dimensional stability of the resulting substrate tends to decrease. The photorefractive index (based on JIS K7142) of the norbornene and ethylene copolymer used in the transparent substrates 12 and 22 is usually about 1.49 to 1.55, and the light transmittance (based on JIS K7361-1 ( Nippon Denshoku Industries Co., Ltd.-Measured with a meter NDH5000)) is about 90.8% to 93.0%. Various known additives such as an ultraviolet absorber, an inorganic or organic antiblocking agent, a lubricant, an antistatic agent, and a stabilizer may be added to the copolymer of norbornene and ethylene for the purpose. MVR (melt volume rate) Temperature 260 ° C., it is preferred that the discharge volume per 10 minutes under a load of 2.16 kg (cm ³⁾ is 0.8 to 2.0 cm ^3/10 min. The 0.8cm less than ^3/10 min, the pressure of the molding machine can not be prepared too high at the time or a film raw material production. Also, 2.0 cm ³ /
When the time is longer than 10 minutes, the strength of the obtained retardation film is too weak to withstand the processing (sputtering or the like) process required for the touch panel or the like.

  A method for obtaining a film for the transparent substrates 12 and 22 from a copolymer of norbornene and ethylene is not particularly limited, and examples thereof include a solution casting method, an extrusion method, and a calendar method. As for the thickness of the copolymer film of norbornene and ethylene, 20-300 micrometers is preferable, More preferably, it is 40-200 micrometers. If the film strength is too thin, the film strength tends to be insufficient, and if the film strength is sufficient, it is not necessary to make it thicker than necessary.

  To improve the wettability and adhesion of the copolymer film of norbornene and ethylene, surface modification such as flame treatment, ultraviolet irradiation treatment, corona discharge treatment, plasma treatment, itro treatment, primer treatment, chemical treatment, etc. Processing may be performed. The corona discharge treatment and the ultraviolet irradiation treatment can be performed in air, nitrogen gas, rare gas, or the like. By such surface modification treatment, the wetting tension on the surface of the cyclic olefin resin film is preferably 450 μN / cm (23 ° C.) or more, and more preferably 500 μN / cm (23 ° C.) or more.

  The shrinkage rate was measured by measuring the length of four sides of a film cut into a size of 100 × 100 mm in units of 0.001 mm using a length measuring machine, and then measuring the measured film in an oven set at 160 ° C. for 30 minutes. Then, the length of the four sides of the film was measured again in units of 0.001 mm using a length measuring device, and the amount of change in the length of each of the four sides was determined. Two sheets were measured, the average value was obtained for each of the MD direction and the TD direction, and the shrinkage was obtained. A negative value means contraction, and a positive value means expansion.

  The method for controlling the retardation by stretching a copolymer film of norbornene and ethylene is not particularly limited, and examples thereof include a roll stretching method, a tenter clip stretching method, and a rolling method.

  In order to evaluate the transparent substrate 12 (22) having the above-described configuration, the present inventors formed a transparent conductive film (ITO film) on the transparent substrate 12 (22), and measured the crystallinity of the transparent conductive film. The results will be described.

First, the copolymerization ratio of norbornene and ethylene is 82:18, a glass transition temperature of 180 ° C., and a copolymer with MVR = 1.5 is melt extruded to have a resin temperature of 300 ° C. and a take-up roll temperature of 130 ° C. And the film was created so that thickness might be set to 100 micrometers. Next, stretching is performed by running between two metal rolls having a roll peripheral speed of 7.0 m / min and a roll peripheral speed of 14.0 m / min while maintaining the film temperature at 190 ° C. A retardation film having a magnification of 2.0 times, a retardation of 138 nm, an Nz coefficient of 1.0, and a film thickness of 86 μm was obtained. The Nz coefficient is one of indices indicating the magnitude relationship between the refractive index components nx, ny, and nz, and is defined by an expression (Expression 2). Here, nx and ny are refractive indexes in the film plane, and nz is a refractive index in a direction perpendicular to the film plane.
Nz = (nx−nz) / | nx−ny | Expression (2)
The dimensional change rate of the obtained retardation film at 160 ° C. in 30 minutes was MD = −0.46% and TD = 0.22%. The strength of the obtained retardation film was sufficiently usable.

  Next, on both surfaces of the obtained retardation film, an ultraviolet curable acrylic paint was used, and a hard coat layer was provided so that the thickness was 6 μm on each side. The pencil hardness of the surface of the obtained film was HB.

An ITO transparent conductive film having a resistance value of 256Ω / □ was formed on one side of the film obtained above by a sputtering method with the film temperature kept at 150 ° C. The measurement result of the crystallinity of the obtained ITO film (Example 1) is shown in FIG.
In addition, an ITO transparent conductive film having a resistance value of 450Ω / □ was formed on one side of the film obtained above by a sputtering method while maintaining the film temperature at 90 ° C. Further, an ITO transparent conductive film having a resistance value of 240Ω / □ was formed by heat treatment at a temperature of 165 ° C. for 1 hour. The measurement result of the crystallinity of the obtained ITO film (Example 2) is shown in FIG.

  Further, the copolymerization ratio of norbornene and ethylene is 82:18, a glass transition temperature of 180 ° C., and a copolymer having an MVR = 1.5 is melt extruded and a resin temperature of 300 ° C. and a take-up roll temperature of 130 ° C. And the film was created so that thickness might be set to 200 micrometers. Next, with a tenter clip type stretching machine, the film was transversely stretched at a speed of 1.0 m / min, a stretching ratio of 2.0 times, and a film temperature of 185.5 ° C., whereby retardation 138 nm, Nz coefficient = 1.5, film A retardation film having a thickness of 95 μm was obtained. The dimensional change rate of the obtained retardation film at 160 ° C. in 30 minutes was MD = −0.06% and TD = −0.12%. The strength of the obtained retardation film was sufficiently usable.

An ultraviolet curable acrylic paint was used on both surfaces of the obtained retardation film, and hard coat layers were provided so that the thicknesses of the front and back surfaces were 6 μm. The pencil hardness of the surface of the obtained film was HB. The film temperature is 1 on one side of the film obtained above.
An ITO transparent conductive film having a resistance value of 236Ω / □ was formed by sputtering while maintaining the temperature at 50 ° C. The measurement result of the crystallinity of the obtained ITO film (Example 3) is shown in FIG.

  As shown in FIGS. 6 to 8, from the measurement results of the degree of crystallinity of the ITO film by X-rays, Examples 1 to 3 all have X-ray intensities due to the (222) orientation unique to ITO around 2θ = about 30 °. It was confirmed that the peak was strong and the crystallinity of the obtained film quality was high.

  In the transparent touch panel 100 having the above configuration, the touch position detection method is the same as that of a conventional capacitive touch panel, and when an arbitrary position on the surface side of the first transparent planar body 1 is touched with a finger or the like. The transparent conductive films 11 and 21 are grounded through the capacitance of the human body at the contact position, and the coordinates of the contact position are calculated by detecting the current value flowing through the transparent conductive films 11 and 21.

Transparent planar member according to the present invention 1 and 2, the copolymerization ratio of norbornene and ethylene is 80: 20~90: 10, MVR (melt volume rate) is 0.8 to 2.0 ^3/10 min The transparent substrates 12 and 22 which are retardation films of retardation 100 nm to 150 nm made of an addition (co) polymer of cyclic olefin having a glass transition temperature of 170 to 200 ° C. are transparent on the transparent substrates 12 and 22. When the conductive films 11 and 21 are formed, or when heat treatment (annealing) after the film formation, the temperature of the transparent substrates 12 and 22 can be set to 140 ° C. or higher. The crystallinity of 11 and 21 can be increased. As a result, the resistance of the transparent conductive films 11 and 21 can be reduced.

  Moreover, as a result of increasing the crystallinity of the transparent conductive films 11 and 21, it is possible to prevent the ITO film from having a strong yellowish color, making the pattern shape of the transparent conductive film less noticeable and the transparent surface The visibility of the body and the touch panel can be improved. Furthermore, since the crystallinity of the transparent conductive films 11 and 21 can be increased and the resistance can be lowered, the thickness of the transparent conductive film can be further reduced, and the visibility can be further improved.

  Furthermore, since the transparent planar body 1 of this embodiment is provided with the polarizing plate 13 on the other surface side (the side opposite to the surface on which the transparent conductive film 11 is formed) of the transparent substrate 12 that is a retardation film. Thus, it is possible to effectively prevent external light incident from the polarizing plate 13 side from being reflected by the surfaces of the patterned transparent conductive films 11 and 21 and passing through the polarizing plate 13 again. Specifically, external light incident on the touch panel 100 (external light incident from the side of the coating layer 4 in FIG. 1) is polarized into horizontal linearly polarized light when passing through the polarizing plate 13 and from the retardation film. The incident light enters the transparent substrate 12. The horizontal linearly polarized light incident on the transparent substrate 12 is polarized into clockwise circularly polarized light, and the surfaces of the patterned transparent conductive films 11 and 21 or the transparent substrate 12 on which the transparent conductive films 11 and 21 are not formed, Reflected on the surface of 22. The reflected clockwise circularly polarized light becomes counterclockwise circularly polarized light at the time of reflection, and is incident on the transparent substrate 12 which is a retardation film again. The counterclockwise circularly polarized light incident on the transparent substrate 12 is polarized into vertical linearly polarized light when passing through the transparent substrate 12 and is incident on the polarizing plate 13. Since the vertical linearly polarized light incident on the polarizing plate 13 cannot pass through the polarizing plate 13, the surfaces of the patterned transparent conductive films 11 and 21 and the transparent substrate on which the transparent conductive films 11 and 21 are not formed. Reflected light on the surfaces of 12 and 22 becomes invisible. By providing such a circularly polarized light structure, it is possible to prevent external light reflection, and as a result, the pattern shape of the patterned transparent conductive films 11 and 21 can be made inconspicuous, and character information displayed by a display device on which a touch panel is installed And image information can be made easier to see.

As mentioned above, although embodiment of the transparent planar bodies 1 and 2 which concern on this invention, and the transparent touch panel 100 which uses this was demonstrated, a specific structure is not limited to the said embodiment. For example, as shown in FIG. 9, the transparent substrate 22 of the second transparent planar body 2 has a copolymerization ratio of norbornene and ethylene of 80:20 to 90:10, and an MVR (melt volume rate) of 0.8. a ~2.0cm ^3/10 min, with a glass transition temperature formed by the light isotropic film made of addition (co) polymer of a cyclic olefin of 170 to 200 ° C., polycarbonate (PC) film or polyvinyl alcohol ( A transparent touch panel may be configured by disposing the retardation film 5 provided with birefringence by stretching the PVA) film.

  Moreover, in the said embodiment, as shown in FIG. 10, the structure by which the undercoat layers 14 and 24 are interposed between the transparent substrates 12 and 22 and the transparent conductive films 11 and 21 is employable. The undercoat layers 14 and 24 are each composed of a laminate of low refractive index layers 14a and 24a and high refractive index layers 14b and 24b having a higher optical refractive index than the low refractive index layers 14a and 24a. It arrange | positions so that the transparent conductive films 11 and 21 may be formed in the refractive index layers 14a and 24a side.

  As the material for the low refractive index layers 14a and 24a, a composition comprising a combination of inorganic oxides such as silicon-tin oxide, silicon oxide, aluminum oxide and the like, a fluorine-based organic material, or a silicon oxide-based material. Examples thereof include sol-gel materials, silicon oxide-based and fluorine-based microporous materials, and those having an optical refractive index of 1.3 to 1.5 are particularly preferable from the viewpoint of improving visibility and productivity. is there. The low refractive index layers 14a and 24a can be formed by sputtering, resistance vapor deposition, electron beam vapor deposition, various wet coating methods, and the like.

  The high refractive index layers 14b and 24b preferably have an optical refractive index of 1.60 to 1.80, more preferably more than 1.65 and not more than 1.80. When the refractive index is less than 1.60, it becomes difficult to approximate the optical characteristics of the portion with and without the transparent conductive film, the pattern shape of the transparent conductive film becomes conspicuous, and good visibility is difficult to obtain. When the optical refractive index exceeds 1.65, very good visibility can be obtained. When the optical refractive index exceeds 1.80, the refractive index difference between the transparent substrates 12 and 22 and the adhesive layer 3 increases, and the reflected light at the material interface, the high refractive index layers 14b and 24b, and the low refractive index. As a result of strong occurrence of interference spots due to optical interference with the reflected light at the interfaces with the layers 14a and 24a, the pattern shape of the transparent conductive films 11 and 21 becomes easy to see and visibility is deteriorated. In addition, there is also a fact that it is difficult to obtain a material and method that can industrially efficiently form a layer having a refractive index exceeding 1.8 and having a hardness and thickness that can improve scratch resistance. Examples of the hard coat material for the high refractive index layers 14b and 24b having a refractive index exceeding 1.65 and not more than 1.80 include resin materials such as acrylic ultraviolet curable resins and thermosetting resins. These resin materials include titanium oxide (refractive index: 2.5 to 2.8), zirconium oxide (refractive index: 2.4), cerium oxide (refractive index: 2.2), and antimony oxide (refractive index: 2). Examples include those obtained by adding fine particles of a metal oxide having a high refractive index such as 0.0 to 2.3). In this case, it is necessary that the metal oxide fine particles to be added have a particle size of about several tens of nanometers so as not to disturb the transparency. The thickness of the high refractive index layers 14b and 24b is preferably 3 μm or more. If it is less than 3 μm, optical interference between the reflected light at the interface with the transparent substrates 12 and 22 and the adhesive layer 3 and the reflected light at the interface between the high refractive index layers 14b and 24b and the low refractive index layers 14a and 24a. As a result of the strong occurrence of interference spots due to the above, the pattern shape of the transparent conductive films 11 and 21 becomes easy to see and visibility is deteriorated, which is not preferable.

  By interposing the undercoat layers 14, 24 having such a configuration between the transparent substrates 12, 22 and the transparent conductive films 11, 21, the transparent conductive film 11, in the visible wavelength range of 450 nm to 700 nm. The difference between the transmission spectrum of the light transmitted through the portion (pattern forming region) 21 and the transmission spectrum of the light transmitted through the portion (non-pattern forming region) where the transparent conductive films 11 and 21 are not formed is reduced. Therefore, it is possible to obtain the transparent planar bodies 1 and 2 and the transparent touch panel 100 with good visibility, in which the pattern shapes of the transparent conductive films 11 and 21 are not noticeable. In addition to the above thin film configuration, the same applies to any configuration that reduces the difference between the transmission spectrum of light transmitted through the pattern formation region and the transmission spectrum of light transmitted through the non-pattern formation region in the visible wavelength range of light. The effect is obtained.

The inventors have prepared a sample having a structure shown in FIG. 11 in which the undercoat layer 14 is interposed between the transparent substrate 12 and the transparent conductive film 11, and when the sample is irradiated with transmitted light, A sensory test was performed to determine whether the pattern shape of the film 11 was not noticeable, and a sheet resistance value was measured.
[Example 1]
This sample has the structure shown in FIG. 11, and the low refractive index layer 14a and the high refractive index layer 14b constituting the undercoat layer 14 are each made of an SiO ₂ thin film (refractive index: 1.46) and a high refractive index hard coat layer (refractive index: 1.65) formed by coating a hard coat agent (Rioduras manufactured by Toyo Ink Manufacturing Co., Ltd.) containing zirconium oxide fine particles. . The patterned transparent conductive film was formed by etching an ITO film formed by sputtering. The thickness of the low refractive index layer 14a (SiO ₂ thin film) is 7.5 nm, the thickness of the high refractive index layer 14b (high refractive index hard coat layer) is 5 μm, and the thickness of the transparent conductive film (ITO film) is 20 nm. . Moreover, the thickness of the adhesion layer 3 is 25 micrometers, and the refractive index of the adhesion layer 3 is 1.47. The transparent substrate 12 has a copolymerization ratio of norbornene and ethylene of 82:18, a glass transition temperature of 180 ° C., and a MVR = 1.5 copolymer at a resin temperature of 300 ° C. by a melt extrusion method. A film was formed so that the thickness was 100 μm at a take-up roll temperature of 130 ° C., and then two different metal rolls with a roll peripheral speed of 7.0 m / min and a roll peripheral speed of 14.0 m / min. By running the film while keeping the film temperature at 190 ° C., a retardation film having a draw ratio of 2.0 times, a retardation of 138 nm, an Nz coefficient of 1.0, and a film thickness of 86 μm is formed. The dimensional change rate of the obtained retardation film at 160 ° C. in 30 minutes is MD = −0.46% and TD = 0.22%. In addition, the refractive index of this retardation film (transparent substrate 12) is 1.53. A hard coat layer 6 made of an acrylic UV curable resin is disposed on the other surface of the transparent substrate 12 (the surface on which the transparent conductive film 11 is not formed). The thickness of this hard coat layer is 5 μm.

  In this sample, the transparent conductive film 11 (ITO film) was formed by sputtering at a temperature of 140 ° C., and then heat treatment (annealing treatment) was performed at a temperature of 140 ° C. for 30 minutes.

  In the case where the sample was irradiated with transmitted light, the pattern shape of the transparent conductive film 11 could not be confirmed in any case, and the result that the visibility was good was obtained. The pattern shape was confirmed by irradiating transmitted light with a three-wavelength fluorescent lamp (27 W) and setting the distance between this sample and the eyes to 20 cm. Further, the determination was performed such that the background of the three-wavelength fluorescent lamp was a white background.

Further, the sheet resistance value was 200Ω / □ or less, and the resistance of the transparent sheet was reduced (see Table 3). The sheet resistance value is Lorester EP, a resistivity meter manufactured by Mitsubishi Chemical Corporation.
Measurement was performed with a four-probe probe.

[Comparative Example 1]
As a comparative example of the above sample, a comparative sample in which the transparent substrate was changed to a ZEONOR film [ZM series manufactured by Nippon Zeon Co., Ltd.] in the configuration of the transparent sheet shown in FIG. The transparent conductive film 11 (ITO film) was formed by sputtering at a temperature of 120 ° C., and then heat-treated (annealed) for 30 minutes at a temperature of 120 ° C. A sensory test was performed to determine whether the pattern shape of the transparent conductive film 11 was not noticeable when irradiated with transmitted light. In Comparative Example 1, the pattern shape of the transparent conductive film 11 was confirmed, and the visibility was poor. (See Table 3). This is thought to be because the ITO film had a strong yellowish color due to insufficient crystallization of the ITO film, and thus the pattern was visually recognized.

  Moreover, since the present inventors conducted the experiment which confirms the change of the retardation value at the time of performing the heat processing (annealing treatment) for 30 minutes at each predetermined temperature about the transparent substrate in Example 1 and Comparative Example 1, The results will be described below. FIG. 12 shows the experimental results. From FIG. 12, the transparent substrate in Example 1 shows a high retardation value of about 134 nm even when the annealing temperature is 150 ° C., whereas the transparent substrate in Comparative Example 1 has an annealing temperature of 140 ° C. It is found that the retardation value is drastically lowered when the temperature exceeds 1, and the retardation value becomes about 128 nm at an annealing temperature of 150 ° C.

  Thus, it turns out that the transparent substrate 12 which comprises the transparent planar body based on this invention can maintain the retardation value also in the high temperature environment over 140 degreeC. As a result, the temperature of the transparent substrates 12 and 22 should be set to 140 ° C. or higher when the transparent conductive films 11 and 21 are formed on the transparent substrates 12 and 22 or when heat treatment (annealing) is performed after the film formation. It is understood that the crystallinity of the transparent conductive films 11 and 21 to be formed can be increased, and the resistance of the transparent conductive films 11 and 21 can be reduced.

DESCRIPTION OF SYMBOLS 100 Transparent touch panel 1 1st transparent planar body 2 2nd transparent planar body 11,21 Transparent electrically conductive film 12,22 Transparent substrate 13 Polarizing plate 14,24 Undercoat layer 14a, 24a Low refractive index layer 14b, 24b High refractive index Layer 3 Adhesive layer

Claims (4)

A transparent planar body having a transparent conductive film patterned on one side of a transparent substrate,
A polarizing plate is provided on the other side of the transparent substrate,
The transparent substrate is a cyclic olefin addition (co) polymer having a copolymerization ratio of norbornene and ethylene of 80:20 to 90:10 and MVR (melt volume rate) of 0.8 to 2.0 cm3 / 10 min. A retardation film having a retardation of 100 nm to 150 nm, and having a shrinkage ratio by heat treatment at 160 ° C. for 30 minutes of 0.5% or less in both MD (flow direction) and TD (vertical direction). Planar body. An undercoat layer is interposed between the transparent substrate and the transparent conductive film,
2. The transparent planar body according to claim 1 , wherein the undercoat layer is composed of a laminate of two or more layers having different optical refractive indexes, and the transparent conductive film is formed on the low refractive index layer side. The low refractive index layer is formed of silicon oxide,
The transparent planar body according to claim 2 , wherein the high refractive index layer is formed of a resin material including metal oxide particles having a light refractive index of 2.0 to 2.8. A transparent touch panel comprising at least one transparent sheet according to any one of claims 1 to 3 , wherein the transparent conductive film of the transparent sheet and a second transparent conductive film different from the transparent conductive film Are arranged in directions facing each other or in the same direction.

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