JP2014135044A - Transparent conductive laminate and image display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive laminate capable of suppressing, in an extremely advanced way, iridescent unevenness from occurring in a displayed image.SOLUTION: A transparent conductive laminate includes at least two transparent base films in a laminated state, and a conductive film is formed at least on one surface of one of the transparent base films. In the at least two transparent base films, a total value of retardation is 4000 nm or more. At least one of the transparent base films has degree of orientation of 3 or more.

Description

The present invention relates to a transparent conductive laminate and an image display device.

Conventionally, a touch panel manufactured by using a transparent conductive laminate in which a metal oxide layer such as ITO is directly laminated as a conductive layer on a transparent base film is widely known. Such a touch panel is disposed on a display panel such as a liquid crystal display panel, and is used as an input unit in, for example, a PDA (Personal Digital Assistants), a portable information terminal, a car navigation system, and the like.

Such a touch panel is often used outdoors, but there is a problem that visibility is easily lowered due to external light reflection on the display screen. In response to such a problem of deterioration in visibility due to reflection of external light, a user often attempts to improve visibility by wearing polarized sunglasses, for example.
However, when the display screen of a conventional touch panel is observed through polarized sunglasses, there is a problem in that unevenness of different colors (hereinafter also referred to as “Nijimura”) occurs on the display screen and display quality is impaired.

For such a problem, for example, in Patent Document 1, two transparent substrate films and a conductive thin film are laminated, and the total retardation value of the two transparent substrate films is 4000 nm or more. A touch panel using the transparent conductive laminate is disclosed.
However, the transparent conductive laminate disclosed in Patent Document 1 may not be able to sufficiently suppress the occurrence of nitrile, and if the generation of nitrite is sufficiently suppressed, the film thickness increases in recent years. It was unsuitable for thinning. For this reason, the transparent conductive laminated body which can suppress generation | occurrence | production of a nidimla more by a thin film more highly was calculated | required.

Japanese Patent No. 4117837

In view of the above-mentioned present situation, the present invention has an object to provide a transparent conductive laminate capable of extremely preventing the occurrence of nitrite in a display image, and an image display device including the transparent conductive laminate. To do.

The present invention is a transparent conductive laminate in which at least two transparent substrate films are laminated and a conductive film is formed on one side of at least one of the transparent substrate films, the at least 2 The total value of the retardation of the transparent substrate film of one sheet is 4000 nm or more, and at least one of the transparent substrate films is a transparent conductive laminate having an orientation degree of 3 or more.
In the transparent conductive laminate of the present invention, it is preferable that at least two transparent substrate films are laminated so that their orientation axes overlap.

Moreover, this invention is also an image display apparatus provided with the transparent conductive laminated body of this invention.
The image display device of the present invention preferably has a light source having a continuous and broad emission spectrum as a backlight light source.
The present invention is described in detail below.
In the present invention, unless otherwise specified, curable resin precursors such as monomers, oligomers, and prepolymers are also referred to as “resins”.

As a result of intensive studies in view of the above-described conventional problems, the present inventors have found that in the transparent conductive laminate having a configuration in which at least two transparent substrate films and a conductive film are laminated, Using the transparent conductive laminate, the total retardation value of the transparent base film is 4000 nm or more, and the degree of orientation of at least one of the two transparent base films is 3 or more. Even when the display screen of the resulting image display device is viewed through polarized sunglasses, it has been found that the occurrence of azimuth can be suppressed to a high degree, and the present invention has been completed.

In the transparent conductive laminate of the present invention, at least two transparent substrate films are laminated, and a conductive film is formed on one side of the at least one transparent substrate film.
In the transparent conductive laminate of the present invention, the transparent substrate film has at least one orientation degree of 3 or more. When the degree of orientation is less than 3, it is not possible to sufficiently suppress the occurrence of nitrite on the display screen of an image display device using the transparent conductive laminate of the present invention.
The preferred lower limit of the degree of orientation is 5, the preferred upper limit is 15, the more preferred lower limit is 7, and the more preferred upper limit is 12.

Here, the degree of orientation is a value represented by Y _max / Y _min when the maximum value of the surface orientation parameter Y of the transparent substrate film is Y _max and the minimum value is Y _min , and the surface The orientation parameter Y is the absorption intensity (I ₁₃₄₀ ) at ₁₃₄₀ cm ⁻¹ on the one-time reflection spectrum of the FTIR-S polarized ATR method measured by rotating the transparent substrate film surface in-plane every 10 ° as the orientation parameter. And the absorption intensity (I ₁₄₁₀ ) at ₁₄₁₀ cm ⁻¹ is obtained by Y = I ₁₃₄₀ / I ₁₄₁₀ .

In the transparent conductive laminate of the present invention, at least two transparent substrate films are laminated, and the transparent substrate film having an orientation degree of 3 or more may be any transparent substrate film. Especially, when it is set as an image display apparatus using the transparent conductive film of this invention, it is preferable that the orientation degree of the transparent base film laminated | stacked at least on the opposite side to the display screen side is 3 or more.
That is, for example, when the transparent conductive laminate of the present invention has a configuration in which two transparent substrate films are laminated, the transparent substrate film laminated on the side opposite to the display screen side of the image display device. In the transparent conductive laminate having an orientation degree of 3 or more and a transparent base film laminated on the display screen side of less than 3, the transparent base film is laminated so that the relationship of the orientation degree is reversed. Compared with the transparent conductive laminate, it is possible to more appropriately prevent the occurrence of nitrile on the display screen.
In the transparent conductive laminate of the present invention, the structure in which at least two transparent substrate films are laminated is not particularly limited. For example, two transparent substrate films are laminated via an adhesive layer. Examples thereof include a structure and a structure in which two transparent substrate films are arranged via a spacer (arranged via an air layer).

As a method for obtaining a transparent substrate film having the above-mentioned degree of orientation, for example, a raw material of the transparent substrate film is melted, and an unstretched film extruded and formed into a sheet is used at a temperature equal to or higher than the glass transition temperature. And a method of performing heat treatment after transverse stretching.
The transverse stretch ratio of the unstretched film is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. When the transverse draw ratio exceeds 6.0 times, the transparency of the obtained transparent base film tends to be lowered, and when the transverse draw ratio is less than 2.5 times, the draw tension becomes small. The degree of orientation of the transparent base film to be obtained is reduced, and the effect of suppressing azimuth is reduced.
Further, in the present invention, before performing the transverse stretching of the unstretched film under the above conditions using a biaxial stretching test apparatus, stretching in the flow direction with respect to the transverse stretching (hereinafter, also referred to as longitudinal stretching) is performed. Also good. In this case, the longitudinal stretching preferably has a stretching ratio of 2 times or less. If the stretching ratio of the longitudinal stretching exceeds 2, the orientation degree value may not be within the preferred range described above.

The transparent substrate film is not particularly limited, and examples thereof include films using polycarbonate, acrylic, polyester, etc. as raw materials. Among them, a polyester film advantageous in terms of cost and mechanical strength is preferable. It is.
In the transparent conductive laminate of the present invention, the at least two transparent substrate films may be films made of the same material or may be films made of different materials.

The transparent substrate film is preferably one in which “optical axis variation” is suppressed. Such a transparent substrate film preferably has a MOR (Maximum Oriented Ratio) value of 1.6 to 2.3, more preferably 1.8 to 2.1. The MOR value is a ratio (maximum value / minimum value) between the maximum value and the minimum value of the transmission microwave intensity measured by a transmission type molecular orientation meter, and is an index of the degree of optical axis variation of the anisotropic film. Is generally used.

In the transparent conductive laminate of the present invention, the at least two transparent substrate films preferably have an in-plane birefringence, but the total retardation value of the at least two transparent substrate films is 4000 nm or more. It is. If the total retardation value is less than 4000 nm, when the transparent conductive laminate of the present invention is used in a liquid crystal display device (LCD), nitrile occurs and the display quality deteriorates. On the other hand, the upper limit of the total retardation of the at least two transparent substrate films is not particularly limited, but is preferably about 30,000 nm. If it exceeds 30,000 nm, the film thickness of the transparent substrate film becomes considerably large, which is not preferable.
The total retardation value of the at least two transparent substrate films is more preferably 5000 to 25000 nm, and still more preferably 7000 to 20,000 nm, from the viewpoint of thinning.
In addition, in the transparent conductive laminated body of this invention, if the sum total of the retardation value of the said at least 2 transparent base film is 4000 nm or more, the retardation value of each transparent base film will not be specifically limited.

The retardation is a refractive index (nx) in a direction having the largest refractive index (slow axis direction) in the plane of the transparent substrate film, and a direction (fast axis direction) orthogonal to the slow axis direction. The refractive index (ny) and the thickness (d) of the transparent substrate film are represented by the following formula.
Retardation (Re) = (nx−ny) × d
The retardation can be measured (measurement angle 0 °, measurement wavelength 589.3 nm) by, for example, KOBRA-WR, KOBRA-IMS manufactured by Oji Scientific Instruments.
Also, using two polarizing plates, the orientation axis direction (major axis direction) of the transparent substrate film is obtained, and the refractive indexes (nx, ny) of two axes orthogonal to the orientation axis direction are Abbe's refraction. Obtained by a rate meter (NAR-4T manufactured by Atago Co., Ltd.). Here, an axis showing a larger refractive index is defined as a slow axis. The thickness d (nm) of the transparent substrate film is measured using an electric micrometer (manufactured by Anritsu), and the unit is converted to nm. Retardation can also be calculated from the product of the difference in refractive index (nx-ny) and the thickness d (nm) of the transparent substrate film.
The refractive index can be measured by using an ellipsometer in addition to the Abbe refractometer, or by using a spectrophotometer (V7100 type, automatic absolute reflectance measurement unit VAR-7010 manufactured by JASCO Corporation) 5 degree reflectivity (R) of a sample in which a black vinyl tape (for example, Yamato vinyl tape No200-38-21 38 mm width) is pasted on the surface opposite to the measurement surface of the transparent substrate film in polarized light (S polarized light) measurement. ) And can be obtained from the following formula.
R (%) = (1-n) ² / (1 + n) ²

In the present invention, the nx-ny (hereinafter also referred to as Δn) is preferably 0.05 or more. When the Δn is less than 0.05, the film thickness of the transparent substrate film necessary for obtaining the retardation value described above may be increased. On the other hand, the Δn is preferably 0.25 or less. If it exceeds 0.25, it becomes necessary to stretch the transparent substrate film excessively, so that the transparent substrate film is liable to be torn and torn, and the practicality as an industrial material may be significantly reduced.
From the above viewpoint, the more preferable lower limit of Δn is 0.07, and the more preferable upper limit is 0.20. In addition, when said (DELTA) n exceeds 0.20, durability of the transparent base film in a moist heat resistance test may be inferior. Since the durability in the heat and humidity resistance test is excellent, a more preferable upper limit of Δn is 0.15.

When the transparent substrate film is a polyester film, the material constituting the polyester film is not particularly limited, but is synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Examples include linear saturated polyester. Specific examples of such polyester include, for example, polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, polyethylene naphthalate (PEN) and isomers thereof (for example, 2,6-PEN, 1,4-PEN, 1,5- PEN, 2,7-PEN, and 2,3-PEN).
Further, the material used for the polyester film may be a copolymer of the above-described polyester, and the polyester is a main component (for example, a component of 80 mol% or more), and a small proportion (for example, less than 20 mol%). It may be blended with other types of resins. Among these polyesters, polyethylene terephthalate or polyethylene-2,6-naphthalate is particularly preferable because of a good balance between mechanical properties and optical properties. In particular, the polyester film is preferably made of polyethylene terephthalate (PET). This is because polyethylene terephthalate is highly versatile and easily available. In the present invention, a transparent conductive laminate capable of producing an image display device with high display quality can be obtained even with a highly versatile film such as PET. Furthermore, PET is excellent in transparency, heat or mechanical properties, can control the retardation by stretching, has a large intrinsic birefringence, and can obtain a large retardation relatively easily even when the film thickness is small.

The method for obtaining the polyester film is not particularly limited as long as the above-described retardation is satisfied. For example, the polyester such as the material PET is melted, and the unstretched polyester extruded into a sheet is subjected to a glass transition. The method of heat-processing after transverse stretching using a tenter etc. at the temperature more than temperature is mentioned.
The transverse stretching temperature is preferably 80 to 130 ° C, more preferably 90 to 120 ° C. Further, the transverse draw ratio is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. When the transverse draw ratio exceeds 6.0 times, the transparency of the resulting polyester film tends to be lowered, and when the draw ratio is less than 2.5 times, the stretching tension becomes small. Birefringence becomes small, and the total value of the retardation described above may not be 4000 nm or more.
Further, in the present invention, before the transverse stretching of the unstretched polyester is performed under the above conditions using a biaxial stretching test apparatus, stretching in the flow direction with respect to the transverse stretching (hereinafter, also referred to as longitudinal stretching) is performed. Also good. In this case, the longitudinal stretching preferably has a stretching ratio of 2 times or less. When the draw ratio of the above-mentioned longitudinal stretching exceeds twice, the value of Δn may not be within the preferred range described above.
The treatment temperature during the heat treatment is preferably 100 to 250 ° C, more preferably 180 to 245 ° C.

Examples of the method for controlling the total retardation value of the polyester film produced by the above-described method to 4000 nm or more include a method of appropriately setting the draw ratio, the draw temperature, and the film thickness of the produced polyester film. Specifically, for example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain high retardation. The lower the stretching ratio, the higher the stretching temperature, and the film thickness. The thinner, the easier it is to obtain low retardation.

The thickness of the polyester film is preferably in the range of 10 to 250 μm. If it is less than 10 μm, tearing, tearing and the like are likely to occur, and the practicality as an industrial material may be significantly reduced. On the other hand, if it exceeds 250 μm, the polyester film is very rigid, the flexibility specific to the polymer film is lowered, and the practicality as an industrial material is also lowered, which is not preferable. The minimum with more preferable thickness of the said polyester film is 25 micrometers, a more preferable upper limit is 200 micrometers, and a still more preferable upper limit is 150 micrometers.

In the transparent conductive laminate of the present invention, it is preferable that at least two of the transparent substrate films are laminated so that their respective orientation axes overlap. By being laminated in this manner, it is possible to more suitably prevent the occurrence of nitrite on the display screen of the image display device using the transparent conductive laminate of the present invention.
The term “laminated so that the orientation axes overlap” means that the angle formed by the orientation axes of the laminated transparent substrate films is within ± 15 °.
Moreover, the said orientation axis means the axis | shaft along the direction with the largest refractive index in the surface orthogonal to the thickness direction of the said transparent base film.

The transparent substrate film preferably has a transmittance in the visible light region of 80% or more, and more preferably 84% or more. In addition, the said transmittance | permeability can be measured by JISK7361-1 (The test method of the total light transmittance of a plastic-transparent material).

In the present invention, the transparent substrate film is subjected to surface treatment such as saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, and flame treatment without departing from the spirit of the present invention. Also good.

In the transparent conductive laminate of the present invention, a conductive film is formed on one side of at least one transparent substrate film.
The conductive film is not particularly limited, and examples thereof include a transparent conductive film made of a metal oxide.
Examples of the transparent conductive film made of the metal oxide include tin-doped indium oxide (ITO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and tin oxide (SnO ₂ ). And a film made of indium oxide (In ₂ O ₃ ), tungsten oxide (WO ₃ ), or the like.
The transparent conductive film may be formed with a pattern similar to a known touch panel electrode.

Examples of the method for forming the conductive film include known methods such as a vacuum deposition method, a sputtering method, and an ion plating method.
The film thickness of the conductive film is preferably 100 to 400 mm, for example.
Further, the conductive film on which the above-described pattern is formed can be formed by performing a known etching process on the conductive film formed by the above method.

The conductive film is formed on one side of at least one transparent substrate film. Examples of such a transparent conductive laminate of the present invention include a structure in which the conductive film is formed between two laminated transparent substrate films.

In the transparent conductive laminate of the present invention, at least two transparent substrate films are laminated, and a conductive film is formed on one side of at least one transparent substrate film. Known functional layers such as a hard coat layer, an antireflection layer, an antiglare layer, and an anti-Newton ring layer may be provided.

The transparent conductive laminate of the present invention can be used as a touch panel member.
As a structure of the transparent conductive laminated body of this invention used for the said touch panel member, transparent base film 2 and transparent base film 2 'like transparent conductive laminated body 1 shown in FIG. 1, for example. A configuration in which the conductive film 3 and the conductive film 3 ′ provided on one side of each face each other through the spacer 5, or the transparent conductive laminate 10 shown in FIG. 2. Examples include a configuration in which the conductive film 13, the transparent base film 12, the conductive film 13 ′, and the transparent base film 12 ′ are laminated in this order.
1 and 2 are cross-sectional views schematically showing an example of a touch panel member using the transparent conductive laminate of the present invention.

The touch panel member shown in FIG. 1 is a resistive film type touch panel member, and the patterns of the conductive films 3 and 3 ′ are usually striped, and the conductive films 3 and 3 ′ are striped. The opposing patterns are arranged so as to be orthogonal to each other. A conventionally known hard coat layer 4 is laminated on the side surface of the transparent base film 2 opposite to the conductive film 3 side. When the touch panel member having such a structure is pressed against the elastic force of the spacer 5 using the input pen 6 on the surface opposite to the transparent base film 2 side of the hard coat layer 4, the conductive film 3 And 3 ′ come into contact with each other, and the electric circuit is turned on, and when the pressing is released, it returns to the original off state and functions as a transparent switch structure.
Further, the touch panel member shown in FIG. 2 is a capacitance type touch panel member, and the conductive films are not in direct contact with each other as in the resistive film type as shown in FIG. A cover glass 14 is laminated on the side opposite to the transparent substrate film 12 side, and the change in capacitance when the surface opposite to the conductive film 13 side of the cover glass 14 is pressed with a fingertip 15 or the like. Detect and detect the position. In the touch panel member shown in FIG. 2, a conventionally known anti-Newton ring layer may be provided on the surface opposite to the conductive film 13 ′ side of the transparent base film 12 ′.

An image display device including the transparent conductive laminate of the present invention is also one aspect of the present invention.
The image display device may be an image display device such as LCD, PDP, FED, ELD (organic EL, inorganic EL), CRT, tablet PC, touch panel, and electronic paper.

The LCD, which is a typical example of the above, includes a transmissive display body and a light source device that irradiates the transmissive display body from the back. When the image display device is an LCD, the transparent conductive laminate of the present invention is formed on the surface of the transmissive display.

When the image display device is a liquid crystal display device, the light source of the light source device is irradiated from the lower side of the transparent conductive laminate of the present invention. Note that a retardation plate may be inserted between the liquid crystal display element and the polarizing plate. An adhesive layer may be provided between the layers of the liquid crystal display device as necessary.

The PDP as the image display device has a surface glass substrate on which an electrode is formed on the surface and a discharge gas sealed between the surface glass substrate to form the electrode and minute grooves on the surface. And a rear glass substrate on which red, green and blue phosphor layers are formed in the groove. When the image display device is a PDP, the surface of the surface glass substrate or the front plate (glass substrate or film substrate) is provided with the transparent conductive laminate of the present invention.

The above image display device is a zinc sulfide or diamine substance that emits light when a voltage is applied: a light emitting material is deposited on a glass substrate, and an ELD device that performs display by controlling the voltage applied to the substrate, or converts an electrical signal into light Alternatively, it may be an image display device such as a CRT that generates an image visible to human eyes. In this case, the transparent conductive laminate of the present invention is provided on the surface of each display device as described above or the surface of the front plate.

Here, when the image display device is a liquid crystal display device, the backlight light source in the liquid crystal display device is not particularly limited, but a light source having a continuous and broad emission spectrum in a wavelength range of 380 to 780 nm is preferable. , White light emitting diode (white LED), organic electroluminescence (EL) and the like. When the backlight light source is a light source having such a continuous and wide emission spectrum, the occurrence of nitrite can be more preferably eliminated.
On the other hand, a cold cathode fluorescent tube (CCFL) is also known as a backlight light source of the image display device. However, since CCFL has a peak at a special wavelength, it may not be possible to suppress the occurrence of nitrite.
The white LED is an element that emits white by combining a phosphor with a phosphor system, that is, a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor. In particular, white light-emitting diodes, which consist of light-emitting elements that combine blue light-emitting diodes using compound semiconductors with yttrium, aluminum, and garnet yellow phosphors, have a continuous and broad emission spectrum, so they have anti-reflection performance. In addition, it is effective for improving contrast in bright places and is excellent in luminous efficiency, and is therefore suitable as the backlight light source. Further, since white LEDs with low power consumption can be widely used, it is possible to achieve an energy saving effect.

In any case, the transparent conductive laminate of the present invention can be used for display display of a television, a computer, electronic paper, a touch panel, a tablet PC or the like. In particular, it can be suitably used for the surface of high-definition image displays such as CRT, liquid crystal panel, PDP, ELD, FED and the like.

Since this invention consists of an above-mentioned structure, it can provide the transparent conductive laminated body which can suppress very much that a display image produces a nidimla.

Sectional drawing which showed typically an example of the resistive film type touch panel member using the transparent conductive laminated body of this invention. Sectional drawing which showed typically an example of the electrostatic capacitance type touch panel member using the transparent conductive laminated body of this invention. 3 is a graph showing an emission spectrum of a white LED used in Example 1. 6 is a graph showing an emission spectrum of CCFL used in Reference Example 1.

The contents of the present invention will be described with reference to the following examples, but the contents of the present invention should not be construed as being limited to these embodiments. Unless otherwise specified, “part” and “%” are based on mass.

<Retardation of transparent substrate film>
The retardation of the transparent substrate film was measured by KOBRA-IMS manufactured by Oji Scientific Instruments (measurement angle 0 °, measurement wavelength 589.3 nm).

<Orientation degree>
The degree of orientation of the transparent substrate film (polyester film) was measured by the following method using UVIR FTS600 (Bio-Rad, FT-IR).
The degree of orientation of the transparent base film is defined by the orientation parameter Y, and the measurement of the orientation parameter Y is based on an infrared absorption spectrum analysis in a single reflection of the FTIR-S polarized ATR method.
That is, the measurement surface of the transparent base film (polyester film) is set in a once-reflective ATR accessory device, the spectrum of one-time reflection is measured, and after the baseline is optimized, the absorption intensity at ₁₃₄₀ cm ⁻¹ (I ₁₃₄₀ ) And the absorption intensity (I ₁₄₁₀ ) at ₁₄₁₀ cm ⁻¹ are quantified. Here, the absorption band of 1340 cm ⁻¹ is ωCH ₂ pitch vibration, which indicates the presence of the trans isomer, and its intensity quantitatively indicates the concentration of the trans isomer, that is, the state of strong orientation in which the polyester molecules are stretched. Is. The absorption band of 1410 cm ⁻¹ is C = C stretching vibration, and the absorption intensity in in-plane rotation is constant, so that the absorption intensity is normalized as a reference band. The orientation parameter Y is represented by the following formula, and the orientation distribution is in the range of 0 ° to 170 ° by in-plane rotation every 10 ° starting from the fast axis direction or slow axis direction of the transparent substrate film. Measure in the same way.
Y = I ₁₃₄₀ / I ₁₄₁₀
The maximum value among the 18 orientation parameters Y thus measured is Y _max , the minimum value is Y _min , and Y _max / Y _min is the degree of orientation of the transparent substrate film.
In addition, the starting point in the measurement of the orientation distribution of the transparent substrate film may be either the fast axis direction or the slow axis direction, and the degree of orientation required even when the starting point is any direction. Are the same.

Example 1
(Preparation of transparent substrate film 1)
The polyethylene terephthalate material was melted at 290 ° C., extruded through a film-forming die, into a sheet form, closely adhered onto a water-cooled and cooled rotating quenching drum, and cooled to produce an unstretched film. This unstretched film was preheated at 120 ° C. for 1 minute in a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), then stretched at 120 ° C. at a stretch ratio of 1.5 times (longitudinal stretching), The stretching direction was stretched at a stretching ratio of 4.5 times in the direction of 90 degrees (transverse stretching) to obtain a transparent base film 1 having an orientation degree of 10.1, a film thickness of 50 μm, and a retardation (Re) = 5000 nm. .

(Formation of conductive film 1)
One side of the transparent substrate film 1 is oxidized with 30 nm thick indium oxide and oxidized by a reactive sputtering method using an indium-tin alloy in an atmosphere of 0.5 Pa composed of 80% argon gas and 20% oxygen gas. A transparent conductive film 1 (hereinafter also referred to as an ITO film) made of a complex oxide with tin was formed to obtain a transparent base film 1 with a conductive film.

(Preparation of transparent substrate film 2)
A transparent base film 2 having an orientation degree of 10.1, a thickness of 100 μm, and a retardation (Re) = 10,000 nm was obtained in the same manner except that the thickness and the draw ratio of the transparent base film 1 were adjusted. .

(Formation of conductive film 2)
Except having used the transparent base film 2, the conductive film 2 was formed in the one side of the transparent base film 2 like the formation of the conductive film 1, and the transparent base film 2 with a conductive film was obtained.

(Formation of hard coat layer)
30% by mass of pentaerythritol triacrylate (PETA) is dissolved in a MIBK solvent on the surface of the transparent base film 2 with a conductive film where the conductive film 2 is not formed, and a photopolymerization initiator (Irg184, manufactured by BASF). ) Was added by a bar coater so that the film thickness after drying was 5 μm to form a coating film. Subsequently, the formed coating film was heated at 70 ° C. for 1 minute to remove the solvent, and the coated surface was fixed by irradiating with ultraviolet rays to obtain a transparent base film 2 with a hard coat layer and a conductive film. .

(Preparation of transparent conductive laminate)
The transparent base film 1 with a conductive film, the hard coat layer and the transparent base film 2 with a conductive film, and the slow axis of the transparent base film 1 and the slow axis of the transparent base film 2 are parallel to each other. Moreover, it laminated | stacked through the adhesion layer so that the transparent base film 1 and the electroconductive film 2 might oppose, and the transparent electroconductive laminated body was produced.

(Evaluation of Nijimura)
On the polarizing plate on the observer side of a liquid crystal monitor (FLATRON IPS226V (manufactured by LG Electronics Japan)) using a white LED as a backlight light source so that the transparent substrate film 1 is on the observer side, a transparent conductive laminate The body was placed to prepare a liquid crystal display device. In addition, it arrange | positioned so that the angle which the slow axis of the transparent base film 1 and the transparent base film 2 of a transparent conductive laminated body and the absorption axis of the polarizing plate by the side of the observer of a liquid crystal monitor may become 45 degrees. .
The display image was observed through polarized sunglasses from the front and oblique directions (about 50 degrees) in a dark place and a bright place (liquid crystal monitor peripheral illuminance of 400 lux), and the presence or absence of nidimra was evaluated according to the following criteria. The observation is performed by 10 people, and the largest number of evaluations are the observation results. The results are shown in Table 1. FIG. 3 shows the emission spectrum of the white LED.
◎: Nijimura is not observed ○: Nizimura is observed, but there is no problem in practical use ×: Nizimura is observed, there is a problem in use XX: Nizimura is strongly observed

(Example 2)
The film thickness and the draw ratio are adjusted, the transparent base film 1 having an orientation degree of 10.1, a film thickness of 20 μm and a retardation (Re) = 2000 nm, and an orientation degree of 10.1, a film thickness of 25 μm and a retardation (Re) = 2500 nm. A transparent conductive laminate was prepared in the same manner as in Example 1 except that the transparent substrate film 2 was prepared and the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Example 3)
The transparent base film 1 having an orientation degree of 7.3, a film thickness of 50 μm, and a retardation (Re) = 4000 nm, and an orientation degree of 7.3, a film thickness of 100 μm, and a retardation (Re) = 8000 nm are adjusted. A transparent conductive laminate was prepared in the same manner as in Example 1 except that the transparent substrate film 2 was prepared and the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Example 4)
The film thickness and the draw ratio are adjusted, the transparent base film 1 having an orientation degree of 3.5, a film thickness of 50 μm, and a retardation (Re) = 2500 nm, and an orientation degree of 10.1, a film thickness of 100 μm, and a retardation (Re) = 1. A transparent conductive laminate was prepared in the same manner as in Example 1 except that a transparent substrate film 2 having a thickness of 10,000 nm was prepared, and the transparent substrate film 1 and the transparent substrate film 2 were used. . The results are shown in Table 1.

(Example 5)
The film thickness and the draw ratio are adjusted, the transparent base film 1 having an orientation degree of 2.0, a film thickness of 50 μm, and a retardation (Re) = 2000 nm, and an orientation degree of 10.1, a film thickness of 100 μm, and a retardation (Re) = 1. A transparent conductive laminate was prepared in the same manner as in Example 1 except that a transparent substrate film 2 having a thickness of 10,000 nm was prepared, and the transparent substrate film 1 and the transparent substrate film 2 were used. . The results are shown in Table 1.

(Comparative Example 1)
The transparent base film 1 having an orientation degree of 2.0, a thickness of 50 μm, and a retardation (Re) = 2000 nm, and an orientation degree of 2.0, a thickness of 100 μm, and a retardation (Re) = 4000 nm are adjusted by adjusting the thickness and the draw ratio. A transparent conductive laminate was prepared in the same manner as in Example 1 except that the transparent substrate film 2 was prepared and the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Comparative Example 2)
The film thickness and the draw ratio are adjusted, the transparent base film 1 having an orientation degree of 2.0, a film thickness of 50 μm, and a retardation (Re) = 2000 nm, and an orientation degree of 2.0, a film thickness of 250 μm, and a retardation (Re) = 1. A transparent conductive laminate was prepared in the same manner as in Example 1 except that a transparent substrate film 2 having a thickness of 10,000 nm was prepared, and the transparent substrate film 1 and the transparent substrate film 2 were used. . The results are shown in Table 1.

(Comparative Example 3)
The film thickness and the draw ratio are adjusted, the transparent base film 1 with an orientation degree of 10.1, a film thickness of 15 μm and a retardation (Re) = 1500 nm, and an orientation degree of 10.1, a film thickness of 20 μm and a retardation (Re) = 2000 nm. A transparent conductive laminate was prepared in the same manner as in Example 1 except that the transparent substrate film 2 was prepared and the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Reference Example 1)
The same method as in Example 1 was used, except that a transparent conductive laminate produced in the same manner as in Example 3 was used and a liquid crystal monitor (LCD2090 UXi (manufactured by NEC)) using CCFL as a backlight light source was used. Nizimura evaluation was conducted. FIG. 4 shows the emission spectrum of CCFL.

(Reference Example 2)
By using the transparent substrate film 1 and the transparent substrate film 2 produced in Example 1, the slow axis of the transparent substrate film 1 and the slow axis of the transparent substrate film 2 are orthogonal to each other, A transparent conductive laminate was prepared in the same manner as in Example 1 except that the total retardation (Re) was set to 5000 nm, and evaluated in the same manner as in Example 1.

As shown in Table 1, the transparent conductive laminate according to the example in which the total retardation value of the transparent substrate film was 4000 nm or more and the degree of orientation of at least one transparent substrate film was 3 or more. All of the liquid crystal monitors that used the were excellent in evaluating Nijimura.
On the other hand, in the liquid crystal monitor using the transparent conductive laminate according to Comparative Examples 1 and 2 in which the degree of orientation of the transparent base film was less than 3, the total value of the retardation of the transparent base film was 4000 nm or more. However, the liquid crystal monitor using the transparent conductive laminate according to Comparative Example 3 inferior to the evaluation of Nizimura and the total retardation value of the transparent substrate film was less than 4000 nm, Even if it was 3 or more, it was inferior to Nizimura's evaluation.
Further, from the comparison between Example 3 and Reference Example 1, it was confirmed that the backlight source of the image display device is preferably a continuous light source having a wide emission spectrum from the viewpoint of preventing azimuth.
Moreover, when the results of Example 2 and Reference Example 2 were compared, the Nizimura evaluation was equivalent, but the total film thickness of the transparent base film 1 and the transparent base film 2 was 45 μm in Example 2, and Reference Example 2 was 150 μm, and it was confirmed that the transparent conductive laminate could be produced with a thinner film when the transparent base films 1 and 2 were arranged so that the slow axes of the transparent base films 1 and 2 were parallel.

When the transparent conductive laminate of the present invention is used in an image display device, it is possible to highly suppress the occurrence of nitrite spots in a display image.

1, 10 Transparent conductive laminate 2, 2 ', 12, 12' Transparent base film 3, 3 ', 13, 13' Conductive film 4 Hard coat layer 5 Spacer 6 Input pen 14 Cover glass 15 Fingertip

Claims (4)

A transparent conductive laminate in which at least two transparent substrate films are laminated, and a conductive film is formed on one side of at least one transparent substrate film,
The total retardation of the at least two transparent substrate films is 4000 nm or more,
At least one of the transparent substrate films has a degree of orientation of 3 or more, and is a transparent conductive laminate. The transparent conductive laminate according to claim 1, wherein at least two transparent substrate films are laminated so that their respective orientation axes overlap. An image display device comprising the transparent conductive laminate according to claim 1. The image display device according to claim 3, wherein the backlight source includes a light source having a continuous and broad emission spectrum.

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