KR20140074838A - Transparent conductive layered body and image display device - Google Patents

Abstract

Provided is a transparent conductive laminate which can effectively prevent a rainbow-like luster from forming on a display image. The transparent conductive laminate has at least two transparent base film sheets laminated. A conductive layer is formed on a surface of at least one of the two transparent base film sheets. The total value of retardation of the two or more transparent base film sheets is larger than 4,000 nm. At least one of the two transparent base film sheets has an orientation degree of 3 or more.

Description

TECHNICAL FIELD [0001] The present invention relates to a transparent conductive laminate and an image display device,

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

BACKGROUND ART Conventionally, a touch panel manufactured 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 input means in PDA (Personal Digital Assistants), portable information terminal, car navigation system, and the like.

Although such a touch panel is often used outdoors, there has been a problem that visibility is likely to deteriorate due to reflection of external light on the display screen. In order to solve the problem of visibility deterioration due to such external light reflection, the user often uses polarized sunglasses to improve the visibility.

However, when a display screen of a conventional touch panel is observed over a polarized sunglass, there has been a problem that a display screen has a problem that a display screen has a different color (hereinafter also referred to as " rainbow spot ").

In order to solve such a problem, for example, Patent Document 1 discloses a transparent conductive laminated body obtained by laminating two transparent base film and conductive thin film and having a total retardation value of 4000 nm or more of two transparent base film A touch panel is disclosed.

However, in the transparent conductive laminate disclosed in Patent Document 1, the occurrence of rainbow streaks can not be sufficiently suppressed, and if the occurrence of rainbow streaks can be suppressed sufficiently, the film thickness becomes thick, It was not suitable for thinning. For this reason, there has been a demand for a transparent conductive laminate which is capable of suppressing the occurrence of rainbow stains at a higher degree and in a thinner film.

Japanese Patent No. 4117837

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transparent conductive laminate capable of extremely suppressing occurrence of rainbow stains on a display image in view of the above situation and an image display apparatus provided with the transparent conductive laminate.

A transparent conductive laminate in which at least two transparent base films are laminated and a conductive film is formed on at least one side of the transparent base film, wherein at least two transparent base films Is at least 4000 nm, and at least one of the transparent base films has a degree of orientation of 3 or more.

In the transparent conductive laminate of the present invention, it is preferable that at least two transparent base films are laminated so that their orientation axes overlap each other.

Further, the present invention is also an image display device comprising the transparent conductive laminate of the present invention.

Further, the image display apparatus of the present invention preferably has a light source that is continuous and has a broad emission spectrum as a backlight source.

Hereinafter, the present invention will be described in detail.

In the present invention, unless otherwise specified, curable resin precursors such as monomers, oligomers and prepolymers are also referred to as "resins ".

Means for Solving the Problems The present inventors have intensively studied in view of the above-mentioned conventional problems, and as a result, found that, in a transparent conductive laminate having a structure in which at least two transparent base films and a conductive film are laminated, Of the transparent conductive laminate is 4000 nm or more and the degree of orientation of at least one of the two transparent base films is 3 or more, the display screen of the image display device using the transparent conductive laminate is visually inspected over the polarized sunglasses It has been found that the occurrence of rainbow stains can be suppressed to a high degree, and the present invention has been accomplished.

In the transparent conductive laminate of the present invention, at least two transparent base films are laminated, and at least one conductive film is formed on one side of the transparent base film.

In the transparent conductive laminate of the present invention, at least one orientation degree of the transparent base film is 3 or more. If the degree of orientation is less than 3, the occurrence of rainbow stains on the display screen of the image display apparatus using the transparent conductive laminate of the present invention can not be sufficiently suppressed.

The preferred lower limit of the degree of orientation is 5, the preferred upper limit is 15, the more preferable lower limit is 7, and the more preferable upper limit is 12.

Here, the degree of orientation refers to a value represented by the maximum value of the surface alignment parameters Y of the transparent substrate film with Y _max, when the Min as Y _min, Y _max / Y _min, the surface alignment parameter Y is an alignment parameter (I ₁₃₄₀ ) at ₁₃₄₀ cm ^-1 and an absorption intensity at 1410 cm ^-1 on a single reflection spectrum of the FTIR-S polarized light ATR method measured by rotating the surface of the transparent base film every 10 ° in the plane (I ₁₄₁₀ ), which is obtained by Y = I ₁₃₄₀ / I ₁₄₁₀ .

In the transparent conductive laminate of the present invention, at least two of the transparent base films are laminated, and the transparent base film having the degree of orientation of 3 or more may be any transparent base film. Among them, when the transparent conductive film of the present invention is used as an image display device, it is preferable that the degree of orientation of the transparent base film laminated at least on the side opposite to the display screen side is 3 or more.

That is, for example, when the transparent conductive laminate of the present invention is a laminated structure of two transparent base films, the degree of orientation of the transparent base film laminated on the side opposite to the display screen side of the image display device is 3 or more, The transparent conductive laminate having a degree of orientation of the transparent base material film laminated on the screen side of less than 3 is more suitably inferior to the transparent conductive laminate in which the transparent base material film is laminated such that the relationship of degree of orientation is reversed .

In the transparent conductive laminate of the present invention, a structure in which at least two transparent base films are laminated is not particularly limited. For example, a structure in which two transparent base films are laminated via an adhesive layer , And a structure in which two transparent base material films are arranged (arranged via an air layer) with a spacer interposed therebetween.

Examples of the method for obtaining the transparent substrate film having the degree of orientation include a method in which a raw material of a transparent base film is melted and extruded into a sheet form to form an unstretched film at a temperature equal to or higher than the glass transition temperature using a tenter, Followed by stretching, followed by heat treatment.

The transverse stretching magnification of the unstretched film is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. If the transverse stretching magnification exceeds 6.0 times, the transparency of the obtained transparent base film tends to be lowered. If the transverse stretching magnification is less than 2.5 times, the stretching tension also becomes smaller, and the degree of orientation of the obtained transparent base film becomes smaller, The effect of suppressing rainbow stains is reduced.

In the present invention, the stretching in the flow direction (hereinafter also referred to as longitudinal stretching) with respect to the transverse stretching is performed before the transverse stretching of the non-stretched film is performed under the above-described conditions using the biaxial stretching tester . In this case, it is preferable that the longitudinal stretching is two times or less the stretching magnification. When the stretching magnification of the longitudinal stretching exceeds 2 times, the value of the degree of orientation may not be within the preferable range described above.

The transparent base film is not particularly limited and, for example, a film using polycarbonate, acrylic, polyester, or the like as a raw material can be cited. Among them, a polyester film favorable in terms of cost and mechanical strength is suitable Do.

In the transparent conductive laminate of the present invention, the at least two transparent base film may be a film comprising the same material or a film containing different materials.

It is preferable that the transparent base film is one in which "optical axis variation" is suppressed. Such a transparent base film preferably has an 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) of the maximum value and the minimum value of the transmission microwave intensity measured by the transmission type molecular alignment system, and is generally used as a measure of the degree of optical axis variation of the anisotropic film.

In the transparent conductive laminate of the present invention, at least two transparent base films preferably have a birefringence in the plane, but the sum of the retardation values of the at least two transparent base films is 4000 nm or more. When the total value of the retardation is less than 4000 nm, when the transparent conductive laminate of the present invention is used in a liquid crystal display (LCD), iridescence spots occur and the display quality is lowered. On the other hand, the upper limit of the total retardation value of the at least two transparent base material films is not particularly limited, but is preferably about 30,000 nm. If it exceeds 30,000 nm, the film thickness of the transparent base film becomes considerably thick, which is not preferable.

The total retardation value of the at least two transparent base material films is more preferably from 5000 to 25000 nm, and further preferably from 7000 to 20,000 nm from the viewpoint of thinning.

Further, in the transparent conductive laminate of the present invention, when the sum of the retardation values of the above-mentioned at least two transparent base films is 4000 nm or more, the retardation value of each transparent base film is not particularly limited.

The term "retardation" refers to a refractive index (nx) in the direction of the greatest refractive index (slow axis direction), a refractive index (ny) in the direction perpendicular to the slow axis direction (fast axis direction) The thickness d of the transparent base film is represented by the following formula.

Retardation (Re) = (nx-ny) xd

The retardation can be measured (measurement angle of 0 DEG, measurement wavelength of 589.3 nm) by, for example, KOBRA-WR, KOBRA-IMS manufactured by Oji Keisei Kikuchi Co.,

The refractive index (nx, ny) of the two axes orthogonal to the orientation axis direction was measured using an Abbe's refractive index meter (NAR manufactured by Atago Co., Ltd.) -4T). Here, an axis indicating a larger refractive index is defined as a slow axis. The thickness d (nm) of the transparent base film is measured using an electric micrometer (manufactured by Anritsu Corporation), and the unit is converted into nm. From the product of the refractive index difference (nx-ny) and the thickness d (nm) of the transparent base film, the retardation can be calculated.

The refractive index can be measured using an ellipsometer in addition to the Abbe's refractive index system or by using a spectrophotometer (V7100 type, automatic absolute reflectance measuring unit VAR-7010, manufactured by Nippon Bunko Co., Ltd.) , The 5-degree reflectance (R) of a sample to which a black vinyl tape (for example, Yamato Vinyl Tape No. 200-38-21 38 mm width) was adhered was measured on the surface opposite to the measurement surface of the transparent base film, .

R (%) = (1-n) ² / (1 + n) ²

In the present invention, it is preferable that the nx-ny (hereinafter also referred to as? N) is 0.05 or more. If? N is less than 0.05, the film thickness of the transparent base film necessary for obtaining the above retardation value may become thick. On the other hand, the above-mentioned? N is preferably 0.25 or less. If it is more than 0.25, it is necessary to excessively stretch the transparent base film, so that the transparent base film tends to be cracked, cracked, and the like, and practical utility as an industrial material may be remarkably lowered.

From the above viewpoints, the more preferable lower limit of? N is 0.07, and the more preferable upper limit is 0.20. Further, when? N exceeds 0.20, the durability of the transparent base film in the wet heat resistance test may be poor. Since the durability in the humid heat resistance test is excellent, the more preferable upper limit of? N is 0.15.

When the transparent base film is a polyester film, the material constituting the polyester film is not particularly limited, but a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester- . Specific examples of such polyesters include 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).

The material used for the polyester film may be a copolymer of the above-mentioned polyester, and the polyester may be a main body (for example, 80 mol% or more) and a small proportion (for example, less than 20 mol% ). ≪ / RTI > Among the above-mentioned polyesters, polyethylene terephthalate or polyethylene-2,6-naphthalate is particularly preferable because it has good balance among mechanical properties and optical properties. Particularly, it is preferable that the polyester film includes polyethylene terephthalate (PET). Polyethylene terephthalate is highly versatile and easy to obtain. In the present invention, it is possible to obtain a transparent conductive laminate capable of producing an image display device having high display quality even in a highly versatile film such as PET. Further, PET has excellent transparency, thermal or mechanical properties, can control retardation by stretching, has a large intrinsic birefringence, and can achieve relatively large retardation even if the film thickness is thin.

The method for obtaining the polyester film is not particularly limited as long as it is a method of satisfying the above retardation. For example, a method of melting an unstretched polyester obtained by melting a polyester such as PET or the like, And transversely stretching at a temperature not lower than the glass transition temperature using a tenter or the like, followed by heat treatment.

The transverse stretching temperature is preferably 80 to 130 占 폚, more preferably 90 to 120 占 폚. The transverse stretch magnification is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. If the transverse stretching magnification exceeds 6.0 times, the transparency of the obtained polyester film tends to be lowered. If the stretching magnification is less than 2.5 times, the stretching tension is also reduced, and therefore the birefringence of the obtained polyester film becomes small, The total retardation value may not be 4000 nm or more.

In the present invention, the stretching in the flow direction (hereinafter also referred to as longitudinal stretching) with respect to the transverse stretching is performed before the transverse stretching of the non-stretched polyester is performed under the above conditions, using the biaxial stretching tester You can do it. In this case, it is preferable that the longitudinal stretching is two times or less the stretching magnification. If the elongation magnification of the longitudinal stretching exceeds 2 times, the value of? N may not be within the preferable range described above.

The treatment temperature during the heat treatment is preferably 100 to 250 占 폚, more preferably 180 to 245 占 폚.

As a method of controlling the total retardation value of the polyester film produced by the above-described method to 4000 nm or more, a method of appropriately setting the stretching magnification, the stretching temperature, and the film thickness of the polyester film to be produced can be mentioned. Specifically, for example, the higher the stretching magnification, the lower the stretching temperature, and the thicker the film thickness, the easier to obtain higher retardation, the lower the stretching ratio, the higher the stretching temperature, The thinner the thickness, the easier to obtain a low retardation.

The thickness of the polyester film is preferably in the range of 10 to 250 mu m. If it is less than 10 mu m, cracking, cracking and the like are liable to occur, and practical utility as an industrial material may be remarkably lowered. On the other hand, if it exceeds 250 탆, the polyester film is very rigid, and the flexibility inherent to the polymer film lowers and practicality as an industrial material also deteriorates. A more preferable lower limit of the thickness of the polyester film is 25 占 퐉, a more preferable upper limit is 200 占 퐉, and a more preferable upper limit is 150 占 퐉.

In the transparent conductive laminate of the present invention, it is preferable that at least two pieces of the transparent base film are laminated so that their orientation axes overlap each other. By stacking in this way, it is possible to more appropriately prevent occurrence of rainbow stains on the display screen of the image display apparatus using the transparent conductive laminate of the present invention.

The lamination of the alignment axes means that the angle formed by the orientation axes of the respective transparent base films laminated is within ± 15 °.

The orientation axis means an axis along a direction in which the refractive index is maximum in a plane orthogonal to the thickness direction of the transparent base film.

The transmittance of the transparent base film in the visible light region is preferably 80% or more, more preferably 84% or more. Further, the transmittance can be measured by JIS K7361-1 (test method for total light transmittance of plastic-transparent material).

In the present invention, the transparent base film may be subjected to surface treatment such as saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment and flame treatment within a range not deviating from the object of the present invention .

In the transparent conductive laminate of the present invention, a conductive film is formed on one side of at least one transparent base film.

The conductive film is not particularly limited, and for example, a transparent conductive film made of a metal oxide can be given.

As the transparent conductive film comprising the metal oxide, for example tin doped indium oxide (ITO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), tin oxide (SnO ₂ ), Indium oxide (In ₂ O ₃ ), tungsten oxide (WO ₃ ), and the like.

The transparent conductive film may have a pattern similar to that of a known touch panel electrode.

Examples of the method of forming the conductive film include known methods such as a vacuum evaporation method, a sputtering method, and an ion plating method.

The thickness of the conductive film is preferably 100 to 400 Å, for example.

The conductive film on which the above-described pattern is formed can be formed by subjecting the conductive film formed by the above method to a known etching treatment.

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

In the transparent conductive laminate of the present invention, at least two transparent base films are laminated, and at least one conductive film is formed on one side of the transparent base film. Alternatively, a conventionally known functional layer, for example, A hard coat layer, an antireflection layer, an antiglare layer, and an anti-Newton ring layer may be formed.

The transparent conductive laminate of the present invention can be used as a touch panel member.

As the structure of the transparent conductive laminate of the present invention used for the touch panel member, for example, the transparent conductive laminate 1 and the transparent base film 2 ' Are arranged with the spacers 5 interposed therebetween such that the conductive films 3 and the conductive films 3 'formed on one side face each other or the transparent conductive laminate 10 shown in Fig. 2 , A conductive film 13, a transparent base film 12, a conductive film 13 'and a transparent base film 12' are stacked 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. The patterns of the conductive films 3 and 3 'are usually in a stripe shape, and the conductive films 3 and 3' Are arranged so as to be orthogonal to each other. A conventionally known hard coat layer 4 is laminated on the surface of the transparent base film 2 opposite to the conductive film 3 side. When the touch panel member having such a constitution is used in which the surface of the hard coat layer 4 opposite to the transparent base film 2 side is pressed against the elastic force of the spacer 5 by using the input pen 6, The conductive films 3 and 3 'are brought into contact with each other to be in the ON state of the electric circuit and function as a transparent switch structure that returns to the original OFF state when the above pressure is released.

The touch panel member shown in Fig. 2 is a capacitive touch panel member, and the conductive films do not come into direct contact with each other like the resist film type shown in Fig. 1, The cover glass 14 is laminated on the side opposite to the side of the film 12 and the change in capacitance when the surface of the cover glass 14 opposite to the side of the conductive film 13 is pressed by the fingertip 15 or the like And detects the position. In the touch panel member shown in Fig. 2, a conventionally known anti-Newton ring layer may be formed on the surface of the transparent base film 12 'opposite to the conductive film 13'.

An image display device having the transparent conductive laminate of the present invention is also one 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, electronic paper and the like.

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

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. Further, a phase difference plate may be inserted between the liquid crystal display element and the polarizing plate. An adhesive layer may be formed between each layer of the liquid crystal display device, if necessary.

The PDP as the image display device has a surface glass substrate on which electrodes are formed on the surface, and a discharge gas is disposed in confrontation with the surface glass substrate, electrodes and minute grooves are formed on the surface, Green, and blue phosphor layers are formed on the rear glass substrate. When the image display device is a PDP, the transparent conductive laminate of the present invention may be provided on the surface of the surface glass substrate or on the front surface plate (glass substrate or film substrate) thereof.

The image display device includes an ELD device for depositing zinc sulfide, a diamine material, and a light emitting material, which emit light when a voltage is applied, on a glass substrate and controlling the voltage applied to the substrate to perform display, Or an image display device such as a CRT that generates a visible image of the image. In this case, the transparent conductive laminate of the present invention is provided on the surface of each display device or the surface of the front surface plate as described above.

When the image display device is a liquid crystal display device, the backlight source of the liquid crystal display device is not particularly limited, but a light source having a continuous and broad emission spectrum in a wavelength region of 380 to 780 nm is preferable, For example, white light emitting diodes (white LEDs), organic electroluminescence (EL), and the like. Since the backlight source is a light source having such a continuous and broad emission spectrum, it is possible to more appropriately eliminate the occurrence of rainbow stains.

On the other hand, a cold-cathode fluorescent tube (CCFL) is also known as a backlight source of the image display device. However, since CCFL has a peak at a special wavelength, the occurrence of rainbow stains may not be suppressed.

The white LED is a device that emits white light by combining a phosphor or a light emitting diode that emits blue light or ultraviolet light using a phosphor compound, that is, a compound semiconductor. Among them, a white light emitting diode including a light emitting element comprising a combination of a blue light emitting diode using a compound semiconductor and a yttrium aluminum / garnet yellow phosphor has a continuous and broad emission spectrum, and therefore has excellent antireflection performance and spot contrast And is also suitable as the backlight light source because it has excellent light emission efficiency. In addition, since a white LED having a small power consumption can be widely used, it is possible to exhibit the effect of energy saving.

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

INDUSTRIAL APPLICABILITY Since the present invention includes the above-described structure, it is possible to provide a transparent conductive laminate capable of extremely suppressing occurrence of rainbow stains on a display image.

1 is a cross-sectional view schematically showing an example of a resistive film-type touch panel member using the transparent conductive laminate of the present invention.
2 is a cross-sectional view schematically showing an example of a capacitive type touch panel member using the transparent conductive laminate of the present invention.
3 is a graph showing the emission spectrum of the white LED used in Example 1. Fig.
4 is a graph showing the emission spectrum of CCFL used in Reference Example 1. Fig.

The content of the present invention will be explained by the following examples, but the content of the present invention is not limited to these embodiments. Unless otherwise stated, " part " and "% " are based on mass.

<Retardation of Transparent Substrate Film>

The retardation of the transparent base film was measured by KOBRA-IMS manufactured by Oji Keisoku Kagaku (measurement angle of 0 °, measurement wavelength: 589.3 nm).

<Orientation>

The degree of orientation of the transparent base film (polyester film) was measured by the following method using UVIR FTS600 (manufactured by Bio-Rad, FT-IR).

The degree of orientation of the transparent base film is defined by the orientation parameter Y, and the orientation parameter Y is measured by infrared absorption spectrum analysis in one reflection of the FTIR-S polarized light ATR method.

That is, the measurement surface of the transparent base film (polyester film) was set in the reflective ATR accessory device once, the spectrum of one reflection was measured, and the absorption intensity at 1340 cm ^-1 (I ₁₃₄₀ ) and the absorption intensity at ₁₄₁₀ cm ^-1 (I ₁₄₁₀ ). Here, the absorption band is 1340㎝ ^-1, ωCH ₂ in the longitudinal vibration, indicates the presence of a trans-isomer, its strength is quantitatively represented by the concentration, i.e. the poly strong elongated, alignment of ester molecules of the trans-isomer. The absorption band at 1410 cm ^-1 is intended to normalize the absorption intensity as a reference band since the absorption intensity at the rotation in the plane becomes constant due to C = C stretching vibration. Further, the orientation parameter Y is expressed by the following formula, and the orientation distribution is rotated in the in-plane direction at every 10 degrees starting from the fast axis direction or the slow axis direction of the transparent base film, do.

Y = I ₁₃₄₀ / I ₁₄₁₀

Thus, a 18-point orientation parameter Y from the maximum value of Y _max, Min of the measurement by the Y _min, Y _max is the / Y _min a degree of orientation of the transparent substrate film.

Further, the starting point in the measurement of the orientation distribution of the transparent base film may be either the fast axis direction or the slow axis direction, and the degree of orientation obtained is the same even when the direction is used as the starting point.

(Example 1)

(Production of transparent base film 1)

The polyethylene terephthalate material was melted at 290 占 폚, extruded into a sheet form through a film forming die, brought into close contact with a cooling quenching drum cooled by water cooling, and cooled to prepare an unstretched film. The unoriented film was preheated at 120 DEG C for 1 minute by a biaxial stretching tester (manufactured by TOYO SEKI Co., Ltd.), and then stretched at 120 DEG C at a stretch magnification of 1.5 times (longitudinal stretch) (Transverse stretching) at a draw ratio of 4.5 times in the direction of the thickness direction of the substrate 1 to obtain a transparent base film 1 having an orientation degree of 10.1, a film thickness of 50 占 퐉, and a retardation (Re) of 5000 nm.

(Formation of conductive film 1)

On one side of the transparent base film 1, indium oxide and tin oxide of 30 nm in thickness were formed by a reactive sputtering method using an indium-tin alloy in an atmosphere of 0.5 Pa containing 80% of argon gas and 20% of oxygen gas A transparent conductive film 1 (hereinafter also referred to as an ITO film) including a complex oxide was formed to obtain a transparent base film 1 having a conductive film.

(Production of transparent base film 2)

A transparent base material film 2 having an orientation degree of 10.1, a film thickness of 100 mu m, and a retardation (Re) of 10,000 nm was obtained in the same manner, except that the transparent base film 1 and the stretching magnification were adjusted.

(Formation of conductive film 2)

A conductive film 2 was formed on one side of the transparent base film 2 in the same manner as the formation of the conductive film 1 except that the transparent base film 2 was used to obtain a transparent base film 2 having a conductive film.

(Formation of hard coat layer)

Pentaerythritol triacrylate (PETA) was dissolved in a MIBK solvent in an amount of 30% by mass and a photopolymerization initiator (Irg184, manufactured by BASF) was added to the surface of the transparent base film 2 having the conductive film on which the conductive film 2 was not formed, To 5% by mass of the composition for a hard coat layer was applied by a bar coater so that the film thickness after drying was 5 占 퐉 to form a coating film. Subsequently, the formed coating film was heated at 70 占 폚 for 1 minute to remove the solvent, and the coated surface was irradiated with ultraviolet rays to fix the transparent substrate film 2 with the hard coat layer and the conductive film.

(Production of transparent conductive laminate)

A transparent base material film 1 having a conductive film and a transparent base material film 2 having a hard coat layer and a conductive film are laminated so that the slow axis of the transparent base material film 1 and the slow axis of the transparent base material film 2 become parallel, And the conductive film 2 were opposed to each other with an adhesive layer interposed therebetween, thereby producing a transparent conductive laminate.

(Evaluation of rainbow stains)

A transparent conductive laminate was disposed on a polarizing plate on the observer side of a liquid crystal monitor (FLATORON IPS226V (manufactured by LG Electronics Japan)) using a white LED as a backlight light source so that the transparent base film 1 was on the observer side, and a liquid crystal display device was manufactured . The angle formed by the slow axis of the transparent base film 1 and the transparent base film 2 of the transparent conductive laminate and the absorption axis of the polarizing plate on the observer side of the liquid crystal monitor was 45 °.

Then, the display image was observed from the front and the oblique direction (about 50 degrees) over the polarized sunglasses at the cow and spot (400 lux at the periphery of the liquid crystal monitor), and the presence or absence of rainbow stains was evaluated according to the following criteria. Observation is performed by 10 people, and the maximum number of evaluations are observed. The results are shown in Table 1. 3 shows the emission spectrum of the white LED.

◎: Rainbow stain is not observed

○: Rainbow stains are observed, but no problem in actual use level

X: Rainbow stains were observed, and there were problems in use

××: Rainbow stain strongly observed

(Example 2)

A transparent substrate film 1 having an orientation degree of 10.1, a film thickness of 20 占 퐉, a retardation (Re) of 2000 nm and a transparent substrate having an orientation degree of 10.1, a film thickness of 25 占 퐉 and a retardation (Re) of 2500 nm were prepared by adjusting the film thickness and the stretch magnification. A transparent conductive laminate was produced in the same manner as in Example 1 except that the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Example 3)

A transparent base material film 1 having an orientation degree of 7.3, a film thickness of 50 占 퐉, a retardation (Re) of 4000 nm and a transparent substrate having an orientation degree of 7.3, a thickness of 100 占 퐉 and a retardation (Re) of 8,000 nm were prepared by adjusting the film thickness and the stretch magnification. A transparent conductive laminate was produced in the same manner as in Example 1 except that the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Example 4)

A transparent base material film 1 having an orientation degree of 3.5, a film thickness of 50 占 퐉, a retardation (Re) of 2500 nm and an orientation degree of 10.1, a film thickness of 100 占 퐉 and a retardation (Re) of 10,000 nm A transparent conductive laminate was produced in the same manner as in Example 1 except that the base film 2 was used and the transparent base film 1 and the transparent base film 2 were used. The results are shown in Table 1.

(Example 5)

A transparent base material film 1 having an orientation degree of 2.0, a film thickness of 50 占 퐉, a retardation (Re) of 2000 nm and an orientation degree of 10.1, a film thickness of 100 占 퐉 and a retardation (Re) of 10,000 nm A transparent conductive laminate was produced in the same manner as in Example 1 except that the base film 2 was used and the transparent base film 1 and the transparent base film 2 were used. The results are shown in Table 1.

(Comparative Example 1)

A transparent substrate film 1 having an orientation degree of 2.0, a film thickness of 50 占 퐉, a retardation (Re) of 2000 nm and an orientation degree of 2.0, a film thickness of 100 占 퐉 and a retardation (Re) of 4000 nm were prepared by adjusting film thickness and stretching magnification A transparent conductive laminate was produced in the same manner as in Example 1 except that the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Comparative Example 2)

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

(Comparative Example 3)

A transparent base material film 1 having an orientation degree of 10.1, a film thickness of 15 占 퐉, retardation (Re) = 1500 nm and an orientation degree of 10.1, a film thickness of 20 占 퐉, and a retardation (Re) A transparent conductive laminate was produced in the same manner as in Example 1 except that the transparent substrate film 1 and the transparent substrate film 2 were used. The results are shown in Table 1.

(Reference Example 1)

A liquid crystal monitor (LCD2090 UXi (manufactured by NEC)) using CCFL as a backlight light source was used in place of the transparent conductive laminate fabricated in the same manner as in Example 3, and in the same manner as in Example 1, . In addition, FIG. 4 shows the emission spectrum of CCFL.

(Reference Example 2)

By using the transparent base film 1 and the transparent base film 2 produced in Example 1 and making the slow axis of the transparent base film 1 and the slow axis of the transparent base film 2 orthogonal to each other, the total retardation (Re) , A transparent conductive laminate was produced in the same manner as in Example 1, and the irregular smudge evaluation was carried out in the same manner as in Example 1.

As shown in Table 1, in the liquid crystal monitor using the transparent conductive laminate according to the embodiment, in which the total retardation value of the transparent base film was 4000 nm or more and the orientation degree of at least one of the transparent base films was 3 or more, All were excellent in evaluating rainbow stains.

On the other hand, even if the total retardation of the transparent base film was 4000 nm or more, the liquid crystal monitor using the transparent conductive laminate of Comparative Examples 1 and 2 in which the degree of orientation of the transparent base film was less than 3 And the total retardation value of the transparent base film was less than 4000 nm, the liquid crystal monitor using the transparent conductive laminate of Comparative Example 3 was inferior to the evaluation of the rainbow stain even if the degree of orientation of the transparent base film was all 3 or more.

In addition, from the comparison between Example 3 and Reference Example 1, it was confirmed that the backlight source of the image display apparatus is preferable in that a light source having a continuous and broad emission spectrum is preferable from the viewpoint of preventing rainbow stains.

In addition, when the results of Example 2 and Reference Example 2 were compared, although the evaluation of rainbow stains was the same, the total film thickness of the transparent base film 1 and the transparent base film 2 was 45 m in Example 2, 150 m in Reference Example 2 , And it was confirmed that the transparent conductive laminate could be formed 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.

INDUSTRIAL APPLICABILITY When the transparent conductive laminate of the present invention is used in an image display apparatus, occurrence of iridescence irregularities on a display image can be suppressed to a high degree.

1, 10: transparent conductive laminate
2, 2 ', 12, 12': transparent substrate film
3, 3 ', 13, 13': conductive film
4: Hard coat layer
5: Spacer
6: Input pen
14: Cover glass
15: Hand tip

Claims (4)

Wherein at least two transparent base films are laminated and at least one transparent base film has a conductive film formed on one side thereof,
Wherein the total value of the retardations of the at least two transparent base films is 4000 nm or more,
Wherein at least one of the transparent base films has an orientation degree of 3 or more. The method according to claim 1,
Wherein at least two transparent base films are laminated so that their orientation axes overlap each other. An image display apparatus comprising the transparent conductive laminate according to claim 1 or 2. The method of claim 3,
An image display apparatus having a light source having a continuous and broad emission spectrum as a backlight source.

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