JP2012173976A - Touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circular polarization configuration touch panel in which a transparent conductive film has a low resistance value and optical transparency and a suppression function of reflected light can be improved by improving heat resistance of a phase difference film.SOLUTION: A phase difference film is formed by laminating a phase difference coat layer 121 made of multiple cured photopolymerizable liquid crystal molecules on a surface of an unstretched film base material 120 made of a cyclic olefin resin. The unstretched film base material 120 is manufactured by a cyclic olefin resin made of an ethylene-norbornene copolymer, a rubbing process is performed on its surface, and the phase difference coat layer 121 made of a polymerizable liquid crystal polymer is formed thereon so that the phase difference film can be manufactured. By using a phase difference film with a transparent conductive film, in which a transparent conductive film is formed on the phase difference film, a touch panel is assembled.

Description

  The present invention relates to a circularly polarizing touch panel including a linearly polarizing layer and a retardation layer.

In an electronic device such as a personal digital assistant (PDA), a notebook PC, an OA device, a medical device, or a car navigation system, a touch panel that gives an input function to the surface of these displays is widely used.
A touch panel generally has a configuration in which a transparent film is formed on a surface of a display such as an LCD (Liquid Crystal Display). .

  For example, as shown in Patent Document 1, a typical transparent conductive film type touch panel is a film with a transparent conductive film in which a transparent electrode (transparent conductive film) such as ITO is formed on one side of a transparent base film. When the user presses an arbitrary position on the film with a transparent conductive film with a finger or a pen during driving, the transparent conductive films come into contact with each other at the pressing position. Energization is performed, and the pressing position is detected from the magnitude of the resistance value from the reference position to the contact position of each transparent conductive film.

  In such a touch panel, an optical TTP (surface low reflection touch panel) in which visibility is improved by suppressing reflection of external light has been developed. For example, Patent Document 2 discloses that a circularly polarizing structure in which a circularly polarizing plate and a λ / 4 retardation film are laminated on the upper and lower surfaces of the touch panel layer allows light from the display to be transmitted and external light reflection to be suppressed. Thus, a technique for improving the visibility is disclosed.

Moreover, in such optical TTP, as shown in Patent Document 3, the transparent film of the touch panel is formed on the surface of the λ / 4 retardation film, so that the retardation film also serves as the base film of the touch panel. A thin optical TTP with a reduced touch panel thickness has also been developed.
As described in Patent Document 4, the quarter retardation film is a method of uniaxially stretching and aligning a resin such as vinylon, polyvinyl alcohol, polycarbonate, polystyrene, nylon, butyl cellulose, cellophane, or the like. The stretched and oriented resin can be obtained by a method of laminating with an optically isotropic resin film having a retardation value of 30 nm or less. The optically isotropic polynorbornene-based resin film can be formed with excellent flexibility when it contains a plasticizer.

Patent Document 5 also discloses a retardation film formed by fixing a nematic hybrid aligned liquid crystal compound.
As described above, the linearly polarizing layer, the first retardation layer, the touch panel layer having the transparent conductive film, and the second retardation layer are sequentially laminated to constitute the optical TTP.

JP 2000-89914 A Japanese Patent Laid-Open No. 10-48625 JP-A-11-134112 JP 2006-285332 A JP 2004-309598 A

  When an optical TTP using a retardation film is manufactured in this way, when a transparent conductive film is formed on the retardation film, the retardation film serves as a base film of the touch panel. However, when the transparent conductive film is heated at a high temperature of 150 ° C. or higher in order to make the resistance low, the retardation film is inevitably heated at a high temperature, and its retardation value changes.

And if the touch panel in which the retardation value of the retardation film is changed is pasted on the display, the light transmission from the display is hindered or the effect of suppressing the reflection of external light is impaired.
In such a background, in the conventional circularly polarized touch panel, in the manufacturing process, the heat treatment of the transparent conductive film is not performed at a very high temperature, and therefore it is difficult to form a low-resistance transparent conductive film. There is.

  In view of the above problems, the present invention provides a retardation film in which a retardation value hardly changes even when heated at a high temperature, thereby making a transparent conductive film have a low resistance value and thickness in a circularly polarizing touch panel. It aims at providing the touch panel which can reduce.

  In order to achieve the above object, a touch panel according to the present invention is a touch panel in which a linearly polarizing layer, a first retardation layer, a touch panel layer having a transparent conductive film, and a second retardation layer are sequentially laminated. In addition, at least one of the first retardation layer and the second retardation layer is formed by curing a plurality of photopolymerizable liquid crystal molecules on the surface of an unstretched film formed using a cycloolefin copolymer as a component. A transparent conductive film constituting the touch panel layer is formed on the surface of the retardation film opposite to the surface on which the retardation coating layer is laminated. It is characterized by being.

The first retardation layer may be composed of a plurality of retardation layers.
The retardation coating layer is preferably constituted by a plurality of liquid crystal molecules bonded in a chain form in a state in which the liquid crystal molecules are aligned in the same direction.
It is preferable that the surface of the unstretched film on which the retardation coating layer is laminated is subjected to a rubbing treatment, and a plurality of liquid crystal molecules are aligned along the direction in which the rubbing treatment is performed.

As the cycloolefin copolymer, 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, addition of the cyclic olefin (co ) It is preferable to use a polymer as a component.
The present invention is particularly effective when the touch panel layer is a resistance film type having a pair of transparent conductive films arranged to face each other with a gap therebetween.

  The present invention is also effective when the touch panel layer is a capacitive touch panel having one or two layers of transparent conductive films for position detection.

  In the touch panel according to the present invention, a plurality of photopolymerizable liquid crystal molecules are cured on the surface of an unstretched film in which at least one of the first retardation layer and the second retardation layer is formed using a cycloolefin copolymer as a component. An unstretched film made of this cycloolefin copolymer is superior in heat resistance compared to stretched films conventionally used as retardation films, and has a plurality of liquid crystals. A retardation coat layer obtained by curing molecules is also excellent in heat resistance.

  That is, the film base material is made of a heat-resistant cycloolefin copolymer and is not stretched. Therefore, even when heated at a high temperature, shrinkage and the like are less likely to occur compared to a stretched film, and optical characteristics are also unlikely to change. . Further, since the retardation coating layer is formed by curing a plurality of liquid crystal molecules, the positional relationship between the liquid crystal molecules is maintained even when heated at a high temperature, so that the optical characteristics are hardly changed.

Accordingly, there is little change in the retardation value of the retardation coating layer during heating.
In particular, if the retardation coating layer is configured in such a manner that a plurality of liquid crystal molecules are arranged in a chain with their orientations aligned, the alignment state of the liquid crystal molecules is maintained even during heating. Since the function is maintained, the change in the retardation value due to heating becomes small.
Therefore, in the touch panel of this invention, a transparent conductive film can be made into low resistance value, and the light transmittance and the suppression function of reflected light can also be made favorable.

In the touch panel according to the present invention, the touch panel layer is provided on the surface opposite to the surface on which the retardation coating layer in the retardation film used in the first retardation layer and / or the second retardation layer is laminated. If the transparent conductive film which comprises is formed, since the phase difference film can serve as the base material of a touch panel layer, the thickness of a touch panel can be reduced.
In this way, in the type of touch panel in which the retardation film also serves as a base material for the touch panel layer, the retardation layer is also heated at a high temperature when the transparent conductive film is heated and annealed. Although it is difficult to obtain both effects of suppressing the change in retardation value, the retardation film of the present invention has heat resistance, so the transparent conductive film on the retardation film is heated at a high temperature (for example, 150 degrees or more). By performing the treatment, the transparent conductive film can have a low resistance, and an effect of suppressing the change in retardation value can be obtained.

  In the touch panel of the present invention, if the surface on which the retardation coating layer is laminated is rubbed in the direction in which a plurality of liquid crystal molecules are aligned, the surface is rubbed by coating the surface with a composition of liquid crystal molecules. Since the liquid crystal molecules can be aligned along the streaks formed by the above, a retardation coating layer having a good retardation function can be easily formed.

In the touch panel of the present invention, in particular, as a cycloolefin copolymer, 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 Those containing cyclic olefin addition copolymer as a component are preferable for securing fluidity during film production and securing the strength of the film.

It is a set figure which shows the structural example of the structure of the resistive film type touchscreen 1 with a polarizing plate concerning Embodiment, and LCD combined with this. 2 is a schematic cross-sectional view of the touch panel 1. FIG. It is a cross-sectional schematic diagram of the retardation coating layer with which the touch panel 1 is provided. It is a figure which shows the manufacturing method of the phase difference film. It is a table | surface which shows the change of the retardation value in each temperature about the retardation film concerning an Example and a comparative example. It is a figure explaining the structure of the electrostatic capacitance type touch panel concerning a modification.

FIG. 1 is a set of diagrams illustrating a configuration example of a resistive film type transparent conductive film touch panel 1 with a polarizing plate (hereinafter simply referred to as “touch panel 1”) according to an embodiment and a configuration example of an LCD combined therewith. is there. FIG. 2 is a cross-sectional view taken along the line AA ′ of the touch panel 1.
As illustrated in FIG. 1, the touch panel 1 is configured by laminating a polarizing plate 10, a retardation film 2 a with a transparent conductive film, a spacer 16, a flexible connector 30, and a retardation film 2 b with a transparent conductive film in order from the top. The polarizing plate 50, the LCD main body 20, and the polarizing plate 60 are laminated in the same order under the retardation film 2b with a transparent conductive film of the touch panel 1, and are bonded together with an adhesive (thickness of about 25 μm). As a whole, an LCD integrated touch panel is configured.

The polarizing plate 10, the polarizing plate 50, and the polarizing plate 60 are linear polarizing plates each having a thickness of 200 μm.
The LCD main body 20 is a TFT type LCD substrate, for example, and has a unit configuration in which a transparent layer, a color filter, a liquid crystal molecular layer, a TFT substrate, and a transparent layer (not shown) are laminated from the top to the bottom.
<Configuration of touch panel 1>
In the touch panel 1, the phase difference film 2 a with a transparent conductive film is formed by laminating a transparent conductive film 13 on the surface of the phase difference film 12, and the phase difference film 2 b with a transparent conductive film is transparent on the surface of the phase difference film 15. The conductive film 14 is laminated.

Each of the retardation films 12 and 15 is a λ / 4 retardation film having a thickness of about 75 to 200 μm, and also serves as a base film for the transparent conductive films 13 and 14 constituting the touch panel layer 40. Thereby, the overall thickness of the touch panel can be reduced (about 500 μm).
The transparent conductive films 13 and 14 are made of ITO (Indium Tin Oxide), antimony-added tin oxide, fluorine-added tin oxide, aluminum-added zinc oxide, potassium-added zinc oxide, silicon-added zinc oxide, potassium-added zinc oxide, zinc oxide-tin oxide. It is a film made of a system, indium oxide-tin oxide system, or various metal materials, and has a thickness of about 30 nm.

  As shown in the sectional view of FIG. 2, the gap between the retardation film 2 a with a transparent conductive film 2 a and the retardation film 2 b with a transparent conductive film is defined by a rib spacer 18. A certain gap 17 is secured between the transparent conductive film 13 and the transparent conductive film 14. The rib spacer 18 is formed of, for example, a double-sided tape having an adhesive layer on both sides of a plastic film, and has a height of 50 μm. Further, on the surface of the retardation film 15, spacers 16 are arranged at regular intervals in a matrix along the xy direction, and unnecessary contact between the transparent conductive films 13 and 14 is suppressed.

In the touch panel 1 described above, the touch panel layer 40 is configured by the transparent conductive film 13 and the transparent conductive film 14 arranged with the gap 17 therebetween, and the retardation films 12 and 15 are laminated on the top and bottom of the touch panel layer 40. The polarizing plate 10 and the polarizing plate 50 are laminated on the upper and lower sides of the phase difference films 12 and 15.
Wiring of the touch panel 1 will be described.

  In the example shown in FIG. 1, the transparent conductive films 13 and 14 are formed in a rectangular shape on the opposing surfaces of the retardation films 12 and 15. The transparent conductive films 13 and 14 are provided with lead lines 131, 132, 141, and 142 along the y-axis and the x-axis to form xy orthogonal coordinates. The lead wires 131, 132, 141, 142 are provided with electrode terminals 131a, 132a, 141a, 142a. Reference numeral 133 denotes a connection line that connects the electrode terminal 132 a and the lead-out line 132.

A flexible connector 30 is interposed between the transparent conductive films 13 and 14 at a predetermined position. In the flexible connector 30, wirings 302 to 305 are disposed on the surface of the flexible substrate 301, and electrode terminals 302 a to 305 a are formed on the wirings 302 to 305.
<Operation of touch panel 1>
When the touch panel 1 is driven, first, a DC voltage of about 0 to 5 V is applied between the lead lines 131 and 132 along the y axis, and when a user inputs, the lead line 141 along the x axis, Position data in the y-axis direction is acquired using 142 as a voltage detection electrode. Next, voltage is applied between the lead lines 141 and 142 along the x axis, and the lead lines 131 and 132 along the y axis are used as voltage detection electrodes to obtain position data in the x axis direction. Get both x and y coordinate information.

The touch panel 1 alternately repeats such detection steps, thereby sequentially acquiring input information from the user and exhibiting a function as a GUI (Graphical User Interface).
<Antireflection function in the touch panel 1>
The linearly polarized light that is emitted upward from the LCD body 20 and passes through the polarizing plate 50 passes through the retardation film 15 to become circularly polarized light, and further passes through the retardation film 12 to become linearly polarized light and passes through the polarizing plate 10. And emitted upward.

  External light incident from above the polarizing plate 10 becomes linearly polarized light at the polarizing plate 10, passes through the retardation film 12, and becomes circularly polarized light. And when this circularly polarized light is reflected by the touch panel layer 40, the reflected circularly polarized light passes through the retardation film 12 again and becomes linearly polarized light, and is incident on the polarizing plate 10, but the vibration plane of this reflected linearly polarized light is Since it is perpendicular to the vibration plane of the incident linearly polarized light, it cannot pass through the polarizing plate 10. Therefore, reflected light is suppressed.

<Configuration of retardation films 12 and 15>
As shown in FIG. 3, the retardation film 12 used in the touch panel 1 is polymerized on the surface of an unstretched film substrate 120 formed of a cyclic olefin-based resin made of an ethylene-norbornene copolymer. The phase difference coating layer 121 made of a liquid crystalline polymer is formed.

The retardation coating layer 121 has a structure in which a plurality of liquid crystal molecules are bonded in a chain shape with their orientations aligned.
The retardation film 15 has the same configuration as that of the retardation film 12.
<Method for Manufacturing Touch Panel 1>
(Method for producing retardation film)
A method for manufacturing the retardation films 12 and 15 used in the touch panel 1 will be described.

Here, a method for producing the retardation film 12 will be described with reference to FIG.
The retardation film 12 is made of a cyclic olefin-based resin made of an ethylene-norbornene copolymer to produce an unstretched film as a film substrate, and the surface is rubbed to form a layer of a polymerizable liquid crystal polymer thereon. To manufacture. Each step will be described in detail below.

Production of unstretched film:
The resin used as the material for the film substrate is a cyclic olefin resin made of an ethylene-norbornene copolymer.
A commercial item can be used for the ethylene-norbornene copolymer. As a commercial item, TOPAS Advanced Polymers company make, brand name "TOPAS" etc. can be mentioned.

  Regarding the copolymerization ratio of norbornene and ethylene, the ratio of norbornene is preferably 80% or more in order to obtain a high glass transition temperature of 170 ° C. or higher. Further, in order to obtain the strength of the film, the ethylene ratio is preferably 10% or more. Therefore, attention should be paid to the weight ratio of ethylene and norbornene. Regarding this point, Table 1 shows heat resistance evaluation data when the weight ratio of norbornene to ethylene is changed. As an evaluation method, the film was cut into A5 size (148 mm × 210 mm), and then placed in a hot air circulating furnace set at 150 ° C. for 30 minutes to examine whether the film was deformed. In addition, when the film was placed on pins raised at the four corners and the central part of the film was hung down, it was judged that deformation due to softening of the film occurred.

* “TOPAS” manufactured by TAP (Polyplastics) Co., Ltd. is used as a cyclic olefin copolymer (COC) film. Copolymers of norbornene and ethylene, UV absorbers, inorganic and organic antiblocking agents, lubricants, antistatic agents Various known additives such as stabilizers may be added.
The water absorption rate (23 ° C./24 hours) of a copolymer of norbornene and ethylene is usually preferably about 0.005 to 0.1%.

The refractive index of the copolymer of norbornene and ethylene is usually about 1.49 to 1.55, and the light transmittance is about 93.0 to 90.8%.
MVR (melt volume rate), temperature 260 ° C. in conformity with JIS K7210, the discharge volume per 10 minutes under a load of 2.16 kg (cm ³⁾ is, in the following 0.8 cm ^3/10 min, fluidity The pressure in the molding machine becomes too high at the time of raw material production or film production, and cannot be produced. In the MVR is 2.0 cm ^3/10 minutes or more, strength of the resulting film becomes weak, processing (coating, film formation, etc.) can not withstand the step after required. Therefore, an appropriate MVR value should be used. About this point, the sensory test in manufacture in each MVR value was done, and the obtained data are shown in Table 2.

* “TOPAS” manufactured by TAP (Polyplastics) Co., Ltd. is used as the cyclic olefin copolymer (COC) film. The cyclic olefin-based resin is formed into a film to produce an unstretched film. Examples of the film forming method include a solution casting method, an extrusion method, and a calendar method. The thickness of the film is preferably 20 μm to 300 μm.

The surface of the film may be subjected to surface modification treatment such as corona treatment.
Rubbing process:
The surface of the film base material prepared as described above is rubbed.
FIG. 4A is a diagram showing how the rubbing process is performed.
A film base material is placed on a horizontally movable stage.

Above the stage, there is a roller whose rotational axis is fixed, and a rubbing cloth (for example, a cloth made of rayon) is wound around the peripheral surface. The stage is moved horizontally in the direction of arrow b while rotating this roller in the direction of arrow a at a constant speed. As the horizontal movement proceeds, the rubbing cloth around the rotating roller rubs the surface of the film substrate.
Thereby, the damage | wound along a rubbing direction is formed in the whole surface of a film base material.

Application of liquid crystal polymer composition:
Next, a liquid crystal polymer composition is applied on the surface of the film substrate that has been rubbed and cured to form a retardation coat layer 121 made of a liquid crystal polymer.
As the liquid crystal polymer composition, a polyfunctional liquid crystal polymer composition or a mixture of liquid crystal and a photocurable monomer is used.

In the polyfunctional liquid crystalline polymer composition, the photopolymerizable liquid crystal monomer composition includes liquid crystal molecules and monomers.
The photopolymerizable liquid crystal monomer composition is composed of a material having at least one photopolymerizable group and at least one mesogen structure. For example, a liquid crystal polymer composed of a monofunctional liquid crystal acrylate having one acrylic group and one biphenyl group is diluted with a bifunctional liquid crystal acrylate having two acrylic groups and one biphenyl group, and is a photopolymerizable initiator. The composition etc. which mixed can be used.

More specifically, the photopolymerizable liquid crystal monomer composition disclosed in JP 2010-132724 A can be used.
As a method for applying the liquid crystal polymer composition onto the film substrate 120, a spin coating method, a bar coating method, a die coater method, a screen printing method, a spray coater method, a gravure coating method and the like are generally known. A coating method can be used.

As shown in FIG. 4B, the applied liquid crystal polymer composition layer 121a contains a large number of liquid crystal molecules, and each liquid crystal molecule is rubbed in the rubbing direction on the surface of the film substrate 120. Orientated along the direction.
The liquid crystal molecules are aligned in this way because the surface of the film substrate 120 has scratches along the rubbing direction, and each liquid crystal molecule is more stable when facing the direction along the scratches. This is probably because of this.

Curing the applied composition:
The solvent is removed from the liquid crystal polymer composition layer 121a and dried to fix the liquid crystal polymer composition layer 121a.
The liquid crystal polymer composition layer 121a is polymerized by irradiation with light.
As a light source for light irradiation, a xenon lamp, a high-pressure mercury lamp, an excimer laser, a sodium lamp, a halogen lamp, a black light, or the like can be used.

By irradiating with ultraviolet rays, the photocurable monomer reacts to crosslink the aligned liquid crystal molecules. It is fixed in a state where the orientations of the aligned liquid crystal molecules are aligned.
Thus, a retardation film in which the retardation coat layer 121 is laminated on the film substrate 120 is produced.
In addition, about the application quantity in the application | coating process of said liquid crystal polymer composition, the retardation value of the phase difference coating layer 121 formed becomes about 138 nm which is 1/4 of wavelength (lambda) = 550 nm which acts most visually. Set to.

(Deposition of transparent conductive film)
A transparent conductive film 13 is formed on the surface of the produced film base 120 with a transparent electrode material such as ITO. This film-forming process can be performed by various thin film formation methods, such as sputtering, the CVD, BVD, the vacuum evaporation method, the plasma method, etc. using a transparent conductive film material.
In general, during film formation, it is preferable to form a thin film on the surface of the film substrate 120 while heating it.

Thus, the retardation film 2a with a transparent conductive film in which the transparent conductive film 13 is laminated on the retardation film 12 is formed. A retardation film 2b with a transparent conductive film in which the transparent conductive film 14 is laminated on the retardation film 15 is also formed in the same manner.
In addition, it can also carry out by roll-to-roll continuously from the process of producing said film base material to a transparent conductive film formation process.

Moreover, in order to adjust the optical characteristic of a transparent conductive film, you may heat and anneal a retardation film with a transparent conductive film after film-forming.
In general, by annealing the transparent conductive film at a high temperature of 150 ° C. or higher, the resistance of the transparent conductive film can be reduced.
(Assembly of touch panel 1)
A retardation film 2a with a transparent conductive film in which the transparent conductive film 13 is formed on the retardation film 12 produced as described above, and a retardation film 2b with a transparent conductive film in which the transparent conductive film 14 is formed on the retardation film 15 Use to assemble the touch panel 1.

In this assembly process, the polarizing plate 10, the retardation film 2 a with transparent conductive film, the spacer 16, the flexible connector 30, and the retardation film 2 b with transparent conductive film are laminated and bonded together with a transparent adhesive. 1 is produced.
<Effect by embodiment>
According to the touch panel 1, the retardation film 12 is formed by laminating the retardation coating layer 121 formed by curing a plurality of photopolymerizable liquid crystal molecules on the surface of an unstretched film substrate 120 made of a cyclic olefin resin. The retardation film 15 is also the same.

The unstretched film made of this cyclic olefin resin is excellent in heat resistance as compared with the stretched film. That is, an unstretched film made of a cyclic olefin resin hardly shrinks even when heated at a high temperature, and its optical characteristics hardly change.
In addition, since the retardation coating layer is formed by curing a plurality of liquid crystal molecules, the positional relationship between the liquid crystal molecules is maintained even when heated at a high temperature. In particular, since the retardation coating layer 121 has a structure in which a plurality of liquid crystal molecules are arranged in a chain with their orientations aligned, the alignment state of the liquid crystal molecules is maintained even during heating. The retardation function is maintained. Therefore, even if the retardation films 12 and 15 are heated at a high temperature of 150 ° C. or higher, the retardation value hardly changes.

Thus, since the phase difference films 12 and 15 have heat resistance, after forming the transparent conductive films 13 and 14 on the phase difference films 12 and 15, annealing is performed at a high temperature of 150 ° C. or higher to obtain a transparent conductive film. The resistance of the film can be reduced, and the change in retardation value is small and stable.
Therefore, when the retardation films 12 and 15 are used, a low-resistance transparent conductive film can be formed on the surface, and a retardation film with a transparent conductive film having a stable retardation value can be formed.

Therefore, the touch panel 1 using the retardation films 12 and 15 can make the transparent conductive film have a low resistance, and can also have a good light transmission and reflected light suppressing function.
<Modifications>
1. In the above-described embodiment, the retardation films 12 and 15 also serve as the base film that supports the transparent conductive films 13 and 14 constituting the touch panel layer 40, but the transparent conductive films 13 and 14 are supported in the touch panel layer 40. The base film to be used may be provided separately from the retardation films 12 and 15. Alternatively, only one of the retardation films 12 and 15 may serve as a base film that supports the transparent conductive film, and the other may be provided with a base film separately.

2. In the said embodiment, although the transparent conductive film type touch panel 1 was comprised using the retardation films 12 and 15, several photopolymerization was carried out on the retardation film similar to retardation films 12 and 15, ie, an unstretched film. A capacitive touch panel can also be configured using a retardation film in which a retardation coating layer formed by curing a liquid crystalline molecule is laminated.
In the case of the capacitance type, in the touch panel layer 40, (1) a transparent conductive film for position detection of two layers is provided via an insulating layer, or (2) a transparent conductive film for position detection of one layer is provided. A membrane is provided.

  (1) When the touch panel layer 40 has a structure in which two transparent conductive films are laminated via an insulating layer, for example, as shown in FIG. A film 70 with a transparent electrode in which a transparent electrode pattern 71a is formed, and a film 80 with a transparent electrode in which a transparent electrode pattern 81 for Y-direction detection is formed on a base film as shown in FIG. The touch panel layer 40 is configured by stacking the layers.

In this case, the shape of each of the transparent electrode patterns 71 and 81 may be a simple line shape. However, in order to improve the sensitivity at the time of touching, each of the transparent electrode patterns 71 and 81 has rhombus portions 71a and 81a on a straight line. It is formed side by side.
The rhombus portions 71a and 81a are arranged in a matrix as a whole, and the rhombus portions 71a of the X direction detection pattern 71 and the rhombus portions 81 of the Y direction detection pattern 81 are arranged so as not to overlap each other.

Also in this capacitive touch panel layer, the same retardation film as the retardation films 12 and 15 can be used as a base film for forming each transparent electrode pattern.
(2) When one layer of the transparent conductive film is formed on the touch panel layer 40, as shown in FIGS. 6C and 6D, the X-direction detecting transparent electrode pattern 91 and Y are formed on one base film. A direction detecting transparent electrode pattern 92 is provided.

The transparent electrode patterns 91 and 92 are formed with rhombus portions 91a and 92a side by side.
The rhombus portions 91a and 92a are arranged in a matrix shape as a whole, and the rhombus portions 91a and 92a are arranged so as not to overlap each other.
In the transparent electrode pattern 91, the conductive portion 91b exists between the rhombus portions 91a, and also in the transparent electrode pattern 92, the conductive portion 92b exists between the rhombus portions 92a. The conduction portion 91 b in the X-direction detection transparent electrode pattern 91 and the conduction portion 92 b in the Y-direction detection transparent electrode pattern 92 intersect with each other through the insulating pattern layer 93.

As described above, the X-direction detecting transparent electrode pattern 91 and the Y-direction detecting transparent electrode pattern 92 are insulated with the insulating pattern layer 93 interposed therebetween at the intersections.
Also in this capacitive touch panel layer, a retardation film similar to the retardation film 12 can also be used as a base film for forming a transparent electrode pattern.
3. In the above embodiment, the orientation of the liquid crystal molecules contained in the composition applied on the surface of the film substrate 120 is aligned using a method of rubbing the surface of the unstretched film substrate 120. Even with a method other than the treatment, it is considered that the orientation of the liquid crystal molecules can be similarly controlled if a fine scratch is made in one direction on the surface of the film substrate 120.

  Further, as a method of aligning the orientation of the liquid crystal molecules, in addition to scratching the surface of the film substrate 120, for example, a method of orienting the chemical structure of the surface of the film substrate 120 in one direction by chemical rubbing, or nanoimprint Thus, it is considered that the orientation of the liquid crystal molecules can be aligned even by a method of forming a fine line along one direction on the surface of the film substrate 120.

Based on the said embodiment, the retardation film concerning an Example and a comparative example was produced, and it tested about the heat resistance.
Example:
As materials for forming the film base 120, the following two types A and B were used.
A: a copolymer having a trade name “TOPAS” (manufactured by TOPAS Advanced Polymers), a copolymerization ratio of norbornene and ethylene of 82:18, a glass transition temperature (Tg) of 180 ° C. and MVR = 1.5 Was formed by a melt extrusion method at a resin temperature of 300 ° C. and a take-up roll temperature of 130 ° C. to produce a film having a thickness of 100 μm (film substrate A).

Here, the glass transition point (Tg) was measured with a differential scanning calorimeter (DSC-60 manufactured by Shimadzu Corporation) in accordance with JIS K7121.
As a material for forming the retardation coating layer 121, a photopolymerizable liquid crystalline polymer composition (SIR series) manufactured by Osaka Organic Chemical Industry Co., Ltd. was used.
After coating the above-mentioned retardation coating material on the film substrate A subjected to corona treatment by the bar coating method, it is dried at 100 ° C. for 5 minutes, and irradiated with ultraviolet rays having an integrated light quantity of 100 mJ / cm ² with a high-pressure mercury lamp. And a retardation coating layer having a thickness of 1 μm was formed. Retardation was 138 nm as measured by an automatic birefringence meter KOBRA 21-ADH manufactured by Oji Scientific Instruments.

Let the retardation film produced using the said film base material A be A1.
Comparative Example 1:
B: As the film substrate 120, a film substrate (ZF-16 manufactured by Nippon Zeon Co., Ltd.) having a thickness of 100 μm and a glass transition temperature (Tg) of 160 ° C. was prepared (film substrate B). ). A retardation film produced by forming a retardation coating layer having a thickness of 1 μm on the film substrate B in the same manner as in Example 1 is designated as B1. When retardation was measured, it was 138 nm.

Comparative Examples 2 and 3:
By stretching the two types of film base materials 120, A and B, retardation films A2 (thickness 86 μm) and B2 (thickness 91 μm) according to the comparative example were produced. When retardation was measured, all were 138 nm.
(Method of heat test)
About retardation film A1, B1 concerning the produced Example, and retardation film A2, B2 concerning a comparative example, the test piece cut into the size of 35 mm square is produced, respectively, The test piece is 110 to 170 degreeC. It heated for 30 minutes at each temperature, the retardation value before and after a heating was measured, and the change of the retardation in each temperature was calculated | required.

Table 3 and FIG. 5 are graphs showing changes in retardation values at various temperatures for the retardation films A1, B1, A2, and B2 according to Examples and Comparative Examples.
This change in retardation value indicates how much the value of λ / 4 in the retardation film has changed from 138 nm after heating compared to before heating. When the change in retardation value is large, the retardation value When the touch panel is assembled using a film, the transparency of the touch panel is lowered or the antireflection effect is lowered.

From FIG. 5, in the retardation films A1 and B1 according to the comparative example, the change in the retardation value is remarkably observed at the heating temperature of 150 ° C. or higher, whereas the retardation films A1 and B1 have the retardation value even at 150 ° C. or higher. It can be seen that the change in is small.
This result shows that, compared with a retardation film produced by stretching a film material, a retardation film in which a retardation coating layer formed by curing a plurality of photopolymerizable liquid crystal molecules on an unstretched film is laminated. Indicates that the heat resistance is superior.

Moreover, although retardation film A1 and B1 both had the change of the retardation value small even 150 degreeC or more, as for retardation film B1 concerning a comparative example, when 150 degreeC or more, the deformation | transformation of the film was confirmed visually.
Therefore, it is proved that by using the retardation films of the examples as the retardation films 12 and 15, the light transmittance of the touch panel and the function of suppressing reflected light can be favorably obtained.

  The touch panel according to the present invention is suitable as a device for providing an input function to the surface of a display such as an LCD.

DESCRIPTION OF SYMBOLS 1 Touch panel 2a, 2b Phase difference film with a transparent conductive film 10, 50, 60 Polarizing plate 12, 15 Phase difference film 13, 14 Transparent conductive film 16 Spacer 20 LCD main body 30 Flexible connector 40 Touch panel layer 120 Film base material 121 Phase difference coating Layer 121a liquid crystal polymer composition layer

Claims (6)

A linearly polarizing layer, a first retardation layer, a touch panel layer having a transparent conductive film, and a second retardation layer are sequentially laminated,
At least one of the first retardation layer and the second retardation layer is
It comprises a retardation film in which a retardation coating layer formed by curing a plurality of photopolymerizable liquid crystal molecules is laminated on the surface of an unstretched film formed using a cycloolefin copolymer as a component,
A touch panel, wherein a transparent conductive film constituting the touch panel layer is formed on a surface of the retardation film opposite to a surface on which the retardation coating layer is laminated. The retardation coating layer is
The touch panel according to claim 1, wherein the plurality of liquid crystal molecules are combined in a chain shape in a state where the liquid crystal molecules are aligned in the same direction. The surface on which the retardation coating layer in the unstretched film is laminated is subjected to a rubbing treatment,
The touch panel according to claim 1, wherein the plurality of liquid crystal molecules are aligned along a direction in which a rubbing process is performed. The cycloolefin copolymer is
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, to a component addition copolymer of cyclic olefin The touch panel according to any one of claims 1 to 3.   The touch panel according to any one of claims 1 to 4, wherein the touch panel layer is formed of a resistive film type touch panel having a pair of transparent conductive films arranged to face each other with a gap therebetween.   The touch panel according to any one of claims 1 to 4, wherein the touch panel layer is a capacitive touch panel having a transparent conductive film for position detection of one layer or two layers.

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