WO2015190428A1 - Laminate and image display device - Google Patents

Abstract

This invention provides a laminate, in which reflective scattering of outside light is minimized despite said laminate containing metal nanowires or a metal mesh, that can be used in an image display device. Said laminate comprises a circularly-polarizing plate and a transparent electrically-conductive film. The circularly-polarizing plate comprises a polarizer, a first retardation layer, and a second retardation layer. The first retardation layer exhibits refractive-index characteristics in which nx > ny ≥ nz, the second retardation layer exhibits refractive-index characteristics in which nz > nx ≥ ny, a multilayer retardation film comprising said first and second retardation layers exhibits an in-plane retardation (Re(550)) between 120 and 160 nm and a thickness-direction retardation (Rth(550)) between 40 and 100 nm, the transparent electrically-conductive film comprises a transparent substrate and a transparent electrically-conductive layer or layers provided on one or both surfaces of said transparent substrate, said transparent substrate exhibits an in-plane retardation (Re) between 1 and 100 nm, and each transparent electrically-conductive layer contains metal nanowires or a metal mesh.

Description

Laminated body and image display device

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

Conventionally, in an image display device having a touch sensor, a transparent conductive film obtained by forming a metal oxide layer such as ITO (indium-tin composite oxide) on a transparent resin film is frequently used as an electrode of the touch sensor. ing. However, the transparent conductive film provided with this metal oxide layer is liable to lose its conductivity due to bending, and has a problem that it is difficult to use in applications that require flexibility such as a flexible display.

On the other hand, a transparent conductive film containing a metal nanowire or a metal mesh is known as a highly flexible transparent conductive film. However, the transparent conductive film has a problem that external light is reflected and scattered by metal nanowires or the like. When such a transparent conductive film is used in an image display device, there are problems that a pattern such as a metal nanowire is visually recognized, contrast is lowered, and display characteristics are inferior.

JP 2004-349061 A JP 2010-243769 A JP 2012-009359 A

The present invention has been made to solve the above-described problems, and an object of the present invention is a laminate that can be used in an image display device, and includes a metal nanowire or a metal mesh, and is capable of receiving external light. It is providing the laminated body by which reflection scattering was suppressed.

The laminate of the present invention includes a circularly polarizing plate and a transparent conductive film, and the circularly polarizing plate, in order from the surface opposite to the transparent conductive film, a polarizer, a first retardation layer, And the second retardation layer, wherein the first retardation layer exhibits a refractive index characteristic of nx> ny ≧ nz, and the second retardation layer has a refractive index of nz> nx ≧ ny. The in-plane retardation Re (550) of the laminated retardation film composed of the first retardation layer and the second retardation layer is 120 nm to 160 nm and the thickness direction retardation Rth ( 550) is 40 nm to 100 nm, the transparent conductive film has a transparent base material, and a transparent conductive layer disposed on at least one side of the transparent base material, and an in-plane retardation of the transparent base material Re is 1 nm to 100 nm, and the transparent conductive layer comprises metal nanowires or metal meshes. No.
In one embodiment, the laminated retardation film does not include an optically anisotropic layer other than the first retardation layer and the second retardation layer.
In one embodiment, the in-plane retardation of the first retardation layer satisfies the relationship Re (450) <Re (550).
In one embodiment, the water absorption rate of the first retardation layer is 3% or less.
In one embodiment, the first retardation layer is obtained by oblique stretching.
In one embodiment, the transparent conductive layer is patterned.
In one embodiment, the metal nanowire is composed of one or more metals selected from the group consisting of gold, platinum, silver, and copper.
According to another aspect of the present invention, an image display device is provided. This image display device includes the laminate and a metal reflector in order from the viewing side.
In one embodiment, the diffuse reflectance is reduced by 90% or more in the laminated portion of the circularly polarizing plate and the transparent conductive film in the image display device.

The laminate of the present invention is a transparent film comprising a circularly polarizing plate having a first retardation layer (nx> ny ≧ nz) and a second retardation layer (nz> nx ≧ ny), and a metal nanowire or a metal mesh. A conductive film. If the laminated body of this invention is used, the emission of the reflected light which external light reflected and produced on the transparent conductive film can be suppressed. Since emission of the reflected light is suppressed, even when a transparent conductive film including metal nanowires or metal meshes is used, a conductive pattern (that is, metal nanowires or metal mesh patterns) is difficult to be recognized, and an image with high contrast is used. A display device can be obtained.

It is a schematic sectional drawing of the image display apparatus by one Embodiment of this invention. It is a schematic sectional drawing which shows an example of the image display apparatus using the laminated body of this invention.

(Definition of terms and symbols)
The definitions of terms and symbols in this specification are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re (550)” is an in-plane retardation measured with light having a wavelength of 550 nm at 23 ° C. Re (550) is obtained by the formula: Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). “Re (450)” is an in-plane retardation measured with light having a wavelength of 450 nm at 23 ° C.
(3) Thickness direction retardation (Rth)
“Rth (550)” is a retardation in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (550) is obtained by the formula: Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film). “Rth (450)” is a retardation in the thickness direction measured with light having a wavelength of 450 nm at 23 ° C.
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.

A. Overall configuration diagram 1 of the laminate is a schematic cross-sectional view of a laminate according to a preferred embodiment of the present invention. The laminate 100 includes a circularly polarizing plate 10 and a transparent conductive film 20 disposed on one side of the circularly polarizing plate 10. The circularly polarizing plate 10 includes a polarizer 11, a first retardation layer 12, and a second retardation layer 13 in order from the surface opposite to the transparent conductive film 20. The first retardation layer 12 exhibits a refractive index characteristic of nx> ny ≧ nz. The second retardation layer exhibits a refractive index characteristic of nz> nx ≧ ny. The transparent conductive film 20 has a transparent substrate 21 and a transparent conductive layer 22 disposed on at least one side of the transparent substrate 21. When the transparent conductive layer is disposed on one side of the transparent substrate, the transparent conductive layer may be disposed on the circular polarizing plate 10 side of the transparent substrate, and is disposed on the opposite side of the circular polarizing plate 10. It may be. Preferably, as shown in FIG. 1, the transparent conductive layer 22 is disposed on the transparent polarizing plate 21 side of the circularly polarizing plate 10. The transparent conductive layer 22 includes the metal nanowire 1. Since the transparent conductive film 20 in this embodiment is comprised from the transparent conductive layer 22 containing the metal nanowire 1, it is excellent in bending resistance, and even if it bends, it is hard to lose electroconductivity. In one embodiment, the metal nanowire 1 can be protected by a protective layer 2 as shown in FIG. In addition, the transparent conductive film 20, the circularly polarizing plate 10, and the first retardation layer 12, the polarizer 11, and the second retardation layer 12 are interposed via any appropriate pressure-sensitive adhesive or adhesive. Can be pasted together (not shown). The laminate of the present invention can be used as a member of an image display device (for example, an electrode of a touch panel, an electromagnetic wave shield). The laminate can be arranged with the circularly polarizing plate side as the viewing side. That is, when this laminated body is applied to an image display device, the circularly polarizing plate 10 and the transparent conductive film 20 are disposed in order from the viewing side, and the polarizer 11 and the first are sequentially disposed from the viewing side. The retardation layer 12 and the second retardation layer 13 are disposed.

The transparent conductive layer may include a metal mesh instead of the metal nanowire or in combination with the metal nanowire. Details of the metal mesh will be described later.

The laminate of the present invention is provided with a circularly polarizing plate on the viewing side of the transparent conductive film, so that (i) external light (natural light) incident on the circularly polarizing plate is converted into circularly polarized light, and (ii) the Circularly polarized light is reflected by the metal nanowire or metal mesh of the transparent conductive film, the circularly polarized state is reversed in the reflected light, and (iii) the reflected light (inverted circularly polarized light) does not pass through the circularly polarizing plate ( That is, the reflected external light can be prevented from being emitted from the laminated body. The circularly polarizing plate has a first retardation layer and a second retardation layer, and the presence of the second retardation layer reduces the angle dependency of the effect of absorbing the reflected light. By using such a circularly polarizing plate, it is possible to prevent emission of reflected light reflected at various angles from the metal nanowire or the metal mesh. In addition, when the laminate of the present invention is applied to an image display device and the laminate is disposed on a reflector with the transparent conductive film facing down, circularly polarized light transmitted through the transparent conductive film is reflected on the reflector. However, by using a transparent substrate having a small in-plane retardation Re as a transparent substrate constituting the transparent conductive film, the circularly polarized state of light transmitted through the transparent conductive film is substantially eliminated. Therefore, the emission of reflected light can be significantly suppressed. As a result of reducing external light reflection in this way, a laminate in which a conductive pattern (that is, a pattern of metal nanowires or metal mesh) is difficult to be recognized is obtained. In addition, when the laminate is used, a display device with high contrast can be obtained.

B. Circularly Polarizing Plate As described above, the circularly polarizing plate includes a polarizer, a first retardation layer, and a second retardation layer. Practically, it may have a protective film that protects the polarizer on at least one side of the polarizer. The polarizer and the protective film can be laminated via any appropriate adhesive or pressure-sensitive adhesive.

Preferably, the circularly polarizing plate has a slow axis of the circularly polarizing plate (substantially, a slow axis of a laminated retardation film composed of a first retardation layer and a second retardation layer). And the absorption axis of the polarizer are arranged so as to be substantially 45 ° (for example, 40 ° to 50 °).

B-1. Polarizer and protective film Any appropriate polarizer is used as the polarizer. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of the polarizer is preferably 0.5 μm to 80 μm.

A uniaxially stretched polarizer by adsorbing iodine to a polyvinyl alcohol film is typically produced by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. The Stretching may be performed after dyeing, may be performed while dyeing, or may be performed after stretching. In addition to stretching and dyeing, for example, treatments such as swelling, crosslinking, adjustment, washing with water, and drying are performed.

Any appropriate film is used as the protective film. Specific examples of the material that is the main component of such a film include cellulose resins such as triacetyl cellulose (TAC), (meth) acrylic, polyester, polyvinyl alcohol, polycarbonate, polyamide, and polyimide. And transparent resins such as polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, and acetate. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Further, a polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition.

B-2. First Retardation Layer As described above, the first retardation layer has a refractive index characteristic of nx> ny ≧ nz. The in-plane retardation Re (550) of the first retardation layer is preferably 80 nm to 200 nm, more preferably 100 nm to 180 nm, and still more preferably 110 nm to 170 nm.

The polarizer and the first retardation layer are laminated so that the absorption axis of the polarizer and the slow axis of the first retardation layer form a predetermined angle. The angle θ formed between the absorption axis of the polarizer and the slow axis of the first retardation layer preferably satisfies the relationship of 35 ° ≦ θ ≦ 55 °, more preferably 38 ° ≦ θ ≦ 52 °, and still more preferably Is 39 ° ≦ θ ≦ 51 °. Within such a range, conversion of incident light into circularly polarized light (above (i)) and absorption of reflected light (above (ii), (iii)) are effectively performed, and the reflected outside light is laminated. Can be prevented from exiting.

In one embodiment, the first retardation layer exhibits the so-called reverse dispersion wavelength dependency. Specifically, in the present embodiment, the in-plane retardation of the first retardation layer satisfies the relationship Re (450) <Re (550). By satisfying such a relationship, an excellent reflection hue can be achieved. Re (450) / Re (550) is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less.

The Nz coefficient of the first retardation layer is preferably 1 to 3, more preferably 1 to 2.5, still more preferably 1 to 1.5, and particularly preferably 1 to 1.3. By satisfying such a relationship, a more excellent reflection hue can be achieved.

The water absorption rate of the first retardation layer is preferably 3% or less, more preferably 2.5% or less, and further preferably 2% or less. By satisfying such a water absorption rate, it is possible to suppress changes in display characteristics over time. In addition, a water absorption rate can be calculated | required based on JISK7209.

The first retardation layer is preferably a stretched polymer film.

Any appropriate resin is used as the resin for forming the polymer film. Specific examples include resins such as cycloolefin resins such as polynorbornene, polycarbonate resins, cellulose resins, polyvinyl alcohol resins, and polysulfone resins. Of these, norbornene resins and polycarbonate resins are preferable.

The polynorbornene refers to a (co) polymer obtained by using a norbornene-based monomer having a norbornene ring as a part or all of a starting material (monomer).

Various products are commercially available as the polynorbornene. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, “Arton” manufactured by JSR, “TOPAS” trade name manufactured by TICONA, and trade names manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

As the polycarbonate resin, an aromatic polycarbonate is preferably used. The aromatic polycarbonate can be typically obtained by a reaction between a carbonate precursor and an aromatic dihydric phenol compound (dihydroxy compound). Specific examples of the carbonate precursor include phosgene, bischloroformate of dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate and the like. Can be mentioned. Among these, phosgene and diphenyl carbonate are preferable.

In one embodiment, the polycarbonate resin includes a structural unit derived from a dihydroxy compound represented by the following general formula (1), and a structural unit derived from a dihydroxy compound represented by the following general formula (2): The dihydroxy compound represented by the following general formula (3), the dihydroxy compound represented by the following general formula (4), the dihydroxy compound represented by the following general formula (5), and the following general formula (6) It includes structural units derived from one or more dihydroxy compounds selected from the group consisting of dihydroxy compounds.

In the general formula (1), each R 1 _- R ₄ are independently a hydrogen atom, a substituted or unsubstituted alkyl group having a carbon number of 1 to 20 carbon atoms, a substituted or unsubstituted C 6 to several 20 carbon atoms Represents a cycloalkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, and X is a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, substituted or unsubstituted 6 carbon atoms. Represents a cycloalkylene group having 20 carbon atoms, or a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, and m and n are each independently an integer of 0 to 5.

 

In the general formula (3), R ₅ represents a substituted or unsubstituted monocyclic cycloalkylene group having 4 to 20 carbon atoms.

In the general formula (4), R ₆ represents a substituted or unsubstituted monocyclic cycloalkylene group having 4 to 20 carbon atoms.

In the general formula (5), R ₇ represents a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, and p is an integer of 2 to 100.

In the general formula (6), R ₈ represents an alkyl group having 2 to 20 carbon atoms or a group represented by the following formula (7).

<Dihydroxy compound represented by general formula (1)>
Specific examples of the dihydroxy compound represented by the general formula (1) include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4-hydroxy-3-ethylphenyl) fluorene, 9,9-bis (4-hydroxy-3-n-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3-isopropylphenyl) ) Fluorene, 9,9-bis (4-hydroxy-3-n-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-sec-butylphenyl) fluorene, 9,9-bis (4-hydroxy) -3-tert-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3-cyclohexylphenyl) fluorene, 9,9-bi (4-hydroxy-3-phenylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-methylphenyl) Fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isopropylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isobutylphenyl) fluorene, 9,9- Bis (4- (2-hydroxyethoxy) -3-tert-butylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-cyclohexylphenyl) fluorene, 9,9-bis (4- (2-Hydroxyethoxy) -3-phenylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3 5-dimethylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert-butyl-6-methylphenyl) fluorene, 9,9-bis (4- (3-hydroxy-2, 2-dimethylpropoxy) phenyl) fluorene and the like are exemplified, preferably 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene 9,9-bis (4- (2-hydroxyethoxy) -3-methylphenyl) fluorene, particularly preferably 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene.

<Dihydroxy compound represented by general formula (2)>
Examples of the dihydroxy compound represented by the general formula (2) include isosorbide, isomannide, and isoide which are in a stereoisomeric relationship. These may be used alone or in combination of two or more. Among these dihydroxy compounds, isosorbide obtained by dehydrating condensation of sorbitol produced from various starches that are abundant as resources and are readily available is easy to obtain and manufacture, optical properties, moldability From the viewpoint of

<Dihydroxy compound represented by general formula (3)>
Examples of the dihydroxy compound represented by the general formula (3) include a compound containing a monocyclic cycloalkylene group (an alicyclic dihydroxy compound). By setting it as a monocyclic structure, the toughness when the polycarbonate-type resin obtained is used as a film can be improved. Representative examples of the alicyclic dihydroxy compound include compounds having a 5-membered ring structure or a 6-membered ring structure. By being a 5-membered ring structure or a 6-membered ring structure, the heat resistance of the obtained polycarbonate resin can be increased. The six-membered ring structure may be fixed in a chair shape or a boat shape by a covalent bond. Specifically, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4- And cyclohexanediol. The dihydroxy compound represented by the general formula (3) may be used alone or in combination of two or more.

<Dihydroxy compound represented by general formula (4)>
Examples of the dihydroxy compound represented by the general formula (4) include a compound containing a monocyclic cycloalkylene group (an alicyclic dihydroxy compound). By setting it as a monocyclic structure, the toughness when the polycarbonate-type resin obtained is used as a film can be improved. As a typical example of the alicyclic dihydroxy compound, R ₆ in the above general formula (4) is the following general formula (Ia) (wherein R ₉ is a hydrogen atom, or substituted or unsubstituted carbon number 1 to carbon number) Represents an alkyl group of 12)). Preferable specific examples of such isomers include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and the like. These are easily available and excellent in handleability. The dihydroxy compound represented by the general formula (4) may be used alone or in combination of two or more.

 

In addition, the compound illustrated above regarding the dihydroxy compound represented by general formula (3) and (4) is an example of the alicyclic dihydroxy compound which can be used, and it is not limited to these at all.

<Dihydroxy compound represented by general formula (5)>
Specific examples of the dihydroxy compound represented by the general formula (5) include diethylene glycol, triethylene glycol, and polyethylene glycol (molecular weight: 150 to 2000).

<Dihydroxy compound represented by general formula (6)>
Specific examples of the dihydroxy compound represented by the general formula (6) include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and spiroglycol represented by the following formula (8). Of these, propylene glycol, 1,4-butanediol, and spiroglycol are preferable.

Structural unit derived from dihydroxy compound represented by general formula (3), structural unit derived from dihydroxy compound represented by general formula (4), derived from dihydroxy compound represented by general formula (5) Among the structural units derived from the dihydroxy compound represented by the general formula (4) and / or the structural unit derived from the dihydroxy compound represented by the general formula (4) It is preferable that the structural unit derived from the dihydroxy compound represented by this is included, and it is more preferable that the structural unit derived from the dihydroxy compound represented by the said General formula (5) is included. By including the structural unit derived from the dihydroxy compound represented by the general formula (5), the stretchability can be improved.

The polycarbonate-based resin of the present embodiment may further contain structural units derived from other dihydroxy compounds.
<Other dihydroxy compounds>
Examples of other dihydroxy compounds include bisphenols. Examples of bisphenols include 2,2-bis (4-hydroxyphenyl) propane [= bisphenol A], 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis ( 4-hydroxy-3,5-diethylphenyl) propane, 2,2-bis (4-hydroxy- (3,5-diphenyl) phenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) ) Propane, 2,2-bis (4-hydroxyphenyl) pentane, 2,4'-dihydroxy-diphenylmethane, bis (4-hydroxyphenyl) methane, bis (4-hydroxy-5-nitrophenyl) methane, 1,1 -Bis (4-hydroxyphenyl) ethane, 3,3-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydride) Loxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone, 2,4′-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3 Examples include '-dichlorodiphenyl ether and 4,4'-dihydroxy-2,5-diethoxydiphenyl ether.

In the polycarbonate resin, the structural unit derived from the dihydroxy compound represented by the general formula (1) is preferably 18 mol% or more, more preferably 20 mol% or more, and further preferably 25 mol% or more. It is. If it is such a range, the 1st phase difference layer which has the wavelength dependence of reverse dispersion can be obtained.

The dihydroxy compound represented by the general formula (3), the dihydroxy compound represented by the general formula (4), the dihydroxy compound represented by the general formula (5) and the dihydroxy represented by the general formula (6) The structural unit derived from one or more dihydroxy compounds selected from the group consisting of compounds is preferably 25 mol% or more, more preferably 30 mol% or more, still more preferably 35 mol% in the polycarbonate-based resin. That's it. If the number of structural units is too small, the toughness of the film may be poor.

The glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 150 ° C. or lower, more preferably 120 ° C. or higher and 140 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to deteriorate, and there is a risk of dimensional change after film formation. If the glass transition temperature is excessively high, the molding stability at the time of film molding may be deteriorated, and the transparency of the film may be impaired. The glass transition temperature is determined according to JIS K 7121 (1987).

The molecular weight of the polycarbonate resin can be represented by a reduced viscosity. The reduced viscosity is measured using a Ubbelohde viscometer at a temperature of 20.0 ° C. ± 0.1 ° C., using methylene chloride as a solvent, precisely adjusting the polycarbonate concentration to 0.6 g / dL. The lower limit of the reduced viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more. The upper limit of the reduced viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, still more preferably 0.80 dL / g. If the reduced viscosity is smaller than the lower limit, there may be a problem that the mechanical strength of the molded product is reduced. On the other hand, if the reduced viscosity is larger than the above upper limit value, the fluidity during molding is lowered, which may cause a problem that productivity and moldability are lowered.

The first retardation layer is produced by stretching a polymer film in at least one direction as described above. Any appropriate method can be adopted as a method for forming the polymer film. For example, a melt extrusion method (for example, a T-die molding method), a cast coating method (for example, a casting method), a calendar molding method, a hot press method, a co-extrusion method, a co-melting method, a multilayer extrusion method, an inflation molding method, etc. It is done. Preferably, a T-die molding method, a casting method, and an inflation molding method are used.

The thickness of the polymer film (unstretched film) can be set to any appropriate value according to desired optical characteristics, stretching conditions described later, and the like. The thickness is preferably 50 μm to 300 μm.

Any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) may be employed for the stretching. Specifically, various stretching methods such as free end stretching, fixed end stretching, free end contraction, and fixed end contraction can be used singly or simultaneously or sequentially. The stretching direction can also be performed in various directions and dimensions such as a horizontal direction, a vertical direction, a thickness direction, and a diagonal direction. The stretching temperature is preferably Tg-30 ° C to Tg + 60 ° C, more preferably Tg-10 ° C to Tg + 50 ° C, with respect to the glass transition temperature (Tg) of the polymer film.

The first retardation layer having the desired optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient) can be obtained by appropriately selecting the stretching method and stretching conditions.

In one embodiment, the first retardation layer is produced by uniaxially stretching a polymer film or uniaxially stretching a fixed end. As a specific example of the fixed end uniaxial stretching, there is a method of stretching in the width direction (lateral direction) while running the polymer film in the longitudinal direction. The draw ratio is preferably 1.1 to 3.5 times.

In another embodiment, the first retardation layer is produced by continuously stretching a long polymer film obliquely in the direction of an angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of θ with respect to the longitudinal direction of the film (slow axis in the direction of angle θ) can be obtained. For example, when laminating with a polarizer Roll-to-roll is possible, and the manufacturing process can be simplified.

Examples of the stretching machine used for the oblique stretching include a tenter type stretching machine capable of adding feed forces, pulling forces, or pulling forces at different speeds in the lateral and / or longitudinal directions. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as a long resin film can be continuously stretched obliquely.

The thickness of the first retardation layer (stretched film) is preferably 20 μm to 100 μm, more preferably 30 μm to 80 μm, and still more preferably 30 μm to 65 μm.

B-3. Second Retardation Layer As described above, the second retardation layer exhibits a relationship in which the refractive index characteristic is nz> nx ≧ ny. If the second retardation layer having such a refractive index characteristic is provided, the angle dependency of the effect of absorbing the reflected light is reduced, and the reflected light reflected from the metal nanowire or the metal mesh at various angles is reduced. Thus, the emission can be prevented.

The thickness direction retardation Rth (550) of the second retardation layer is preferably −260 nm to −10 nm, more preferably −230 nm to −15 nm, and further preferably −215 nm to −20 nm. If it is such a range, the said effect will become remarkable.

In one embodiment, the second retardation layer has a refractive index of nx = ny. Here, “nx = ny” includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. Specifically, Re (550) is less than 10 nm. In another embodiment, the second retardation layer exhibits a relationship in which the refractive index is nx> ny. In this case, the in-plane retardation Re (550) of the second retardation layer is preferably 10 nm to 150 nm, more preferably 10 nm to 80 nm.

The second retardation layer can be formed of any appropriate material. A liquid crystal layer fixed in homeotropic alignment is preferable. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the liquid crystal layer include the liquid crystal compounds and methods described in JP-A-2002-333642, [0020] to [0042]. In this case, the thickness is preferably 0.1 μm to 5 μm, more preferably 0.2 μm to 3 μm.

As another preferred specific example, the second retardation layer may be a retardation film formed of a fumaric acid diester resin described in JP 2012-32784 A. In this case, the thickness is preferably 5 μm to 50 μm, more preferably 10 μm to 35 μm.

B-4. Laminated retardation film A laminated retardation film is constituted by the first retardation layer and the second retardation layer. Preferably, the laminated retardation film does not include an optically anisotropic layer other than the first retardation layer and the second retardation layer. The optically anisotropic layer is a layer having an in-plane retardation Re (550) exceeding 10 nm and / or a thickness direction retardation Rth (550) being less than −10 nm or exceeding 10 nm.

The in-plane retardation (550) Re of the laminated retardation film composed of the first retardation layer and the second retardation layer is 120 nm to 160 nm, more preferably 130 nm to 150 nm. Preferably, it is 135 nm to 145 nm. Within such a range, conversion of incident light into circularly polarized light (above (i)) and absorption of reflected light (above (ii), (iii)) are effectively performed, and the reflected outside light is laminated. Can be prevented from exiting.

Thickness direction retardation Rth (550) of the laminated retardation film composed of the first retardation layer and the second retardation layer is 40 nm to 100 nm, more preferably 50 nm to 90 nm, Preferably, it is 60 nm to 80 nm. If it is such a range, it can apply to a display apparatus and can obtain the laminated body which can improve a viewing angle characteristic and can suppress the change of a display characteristic.

B-5. Method for Producing Circular Polarizing Plate As a method for producing the circular polarizing plate, any appropriate method can be adopted. In one embodiment, the longitudinal direction of the polarizer and the polarizer having an absorption axis in the longitudinal direction and the elongated first or second retardation layer in the longitudinal direction are respectively conveyed in the longitudinal direction. Laminating while aligning the longitudinal direction of the retardation layer to obtain a laminated film, and laminating the laminated film and the elongated second or first retardation layer while transporting each in the longitudinal direction And a step of laminating so that the longitudinal direction of the film and the longitudinal direction of the retardation layer are aligned. A long retardation film and a long retardation film are produced by laminating a long first retardation layer and a long second retardation layer. You may manufacture by laminating | stacking. Here, the angle θ formed between the absorption axis of the polarizer and the slow axis of the first retardation layer preferably satisfies the relationship of 35 ° ≦ θ ≦ 55 °, more preferably 38 ° ≦ θ ≦ 52 °, more preferably 39 ° ≦ θ ≦ 51 °.

The long first retardation layer may have a slow axis in the direction of an angle θ with respect to the longitudinal direction. According to such a configuration, as described above, roll-to-roll is possible in manufacturing the polarizing plate, and the manufacturing process can be significantly shortened.

C. Transparent conductive film The transparent conductive film includes a transparent substrate and a transparent conductive layer disposed on at least one side of the transparent substrate. The transparent conductive layer includes metal nanowires or metal mesh.

The total light transmittance of the transparent conductive film is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. By providing a transparent conductive layer containing metal nanowires or metal mesh, a transparent conductive film having a high total light transmittance can be obtained.

The surface resistance value of the transparent conductive film is preferably 0.1Ω / □ to 1000Ω / □, more preferably 0.5Ω / □ to 500Ω / □, and particularly preferably 1Ω / □ to 250Ω / □. It is. By providing a transparent conductive layer containing metal nanowires or metal mesh, a transparent conductive film having a small surface resistance value can be obtained. In addition, when forming a transparent conductive layer containing metal nanowires, a small amount of metal nanowires can exhibit excellent conductivity with a small surface resistance, as described above. A conductive film can be obtained.

C-1. Transparent substrate The in-plane retardation Re of the transparent substrate is 1 nm to 100 nm, preferably 1 nm to 50 nm, more preferably 1 nm to 10 nm, still more preferably 1 nm to 5 nm, and particularly preferably. 1 nm to 3 nm. The in-plane retardation Re of the transparent substrate is preferably as small as possible. If a transparent base material having a small in-plane retardation is used, depolarization in the transparent conductive film is prevented, and emission of reflected light can be suppressed.

The absolute value of the thickness direction retardation Rth of the transparent substrate is preferably 100 nm or less, more preferably 75 nm or less, still more preferably 50 nm or less, particularly preferably 10 nm or less, and most preferably 5 nm or less.

The thickness of the transparent substrate is preferably 20 μm to 200 μm, more preferably 30 μm to 150 μm. If it is such a range, a transparent base material with a small phase difference can be obtained.

The total light transmittance of the transparent substrate is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more.

Any appropriate material can be used as the material constituting the transparent substrate. Specifically, for example, a polymer substrate such as a film or a plastics substrate is preferably used. Excellent smoothness of transparent substrate and wettability to transparent conductive composition (metal nanowire dispersion, protective layer forming composition), and productivity can be greatly improved by continuous production using rolls. It is. Preferably, a material capable of expressing the in-plane retardation Re in the above range is used.

The material constituting the transparent base material is typically a polymer film mainly composed of a thermoplastic resin. Examples of the thermoplastic resin include cycloolefin resins such as polynorbornene; acrylic resins; low retardation polycarbonate resins. Among these, a cycloolefin resin or an acrylic resin is preferable. If these resins are used, a transparent substrate having a small retardation can be obtained. Moreover, these resins are excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like. You may use the said thermoplastic resin individually or in combination of 2 or more types.

Specific examples of the polynorbornene are as described in the above section B-2.

The acrylic resin refers to a resin having a repeating unit derived from (meth) acrylic acid ester ((meth) acrylic acid ester unit) and / or a repeating unit derived from (meth) acrylic acid ((meth) acrylic acid unit). . The acrylic resin may have a structural unit derived from a (meth) acrylic acid ester or a (meth) acrylic acid derivative.

In the acrylic resin, the total content of the structural units derived from the (meth) acrylic acid ester unit, (meth) acrylic acid unit, and (meth) acrylic acid ester or (meth) acrylic acid derivative is the acrylic resin. The amount is preferably 50% by weight or more, more preferably 60% by weight to 100% by weight, and particularly preferably 70% by weight to 90% by weight with respect to all the structural units constituting the resin. If it is such a range, the transparent base material of a low phase difference can be obtained.

The acrylic resin may have a ring structure in the main chain. By having a ring structure, it is possible to improve the glass transition temperature while suppressing an increase in retardation of the acrylic resin. Examples of the ring structure include a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, an N-substituted maleimide structure, and a maleic anhydride structure.

The acrylic resin may have other structural units. Examples of other structural units include styrene, vinyl toluene, α-methyl styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, vinyl acetate, methallyl alcohol, allyl alcohol, 2-hydroxymethyl-1-butene, α- 2- (hydroxyalkyl) acrylic acid ester such as hydroxymethylstyrene, α-hydroxyethylstyrene, methyl 2- (hydroxyethyl) acrylate, 2- (hydroxyalkyl) acrylic acid such as 2- (hydroxyethyl) acrylic acid, etc. And a structural unit derived from the monomer.

Specific examples of the acrylic resin include, in addition to the acrylic resins exemplified above, JP-A No. 2004-168882, JP-A No. 2007-261265, JP-A No. 2007-262399, and JP-A No. 2007-297615. Examples thereof also include acrylic resins described in JP-A-2009-039935, JP-A-2009-052021, and JP-A-2010-284840.

The glass transition temperature of the material constituting the transparent substrate is preferably 100 ° C. to 200 ° C., more preferably 110 ° C. to 150 ° C., and particularly preferably 110 ° C. to 140 ° C. If it is such a range, the transparent conductive film excellent in heat resistance can be obtained.

The transparent substrate may further contain any appropriate additive as necessary. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. Etc. The kind and amount of the additive used can be appropriately set according to the purpose.

As a method for obtaining the transparent substrate, any suitable molding method is used, for example, compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method. , And a solvent casting method and the like can be appropriately selected. Among these production methods, an extrusion molding method or a solvent casting method is preferably used. This is because the smoothness of the obtained transparent substrate can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used.

If necessary, various surface treatments may be performed on the transparent substrate. As the surface treatment, any appropriate method is adopted depending on the purpose. For example, low-pressure plasma treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment may be mentioned. In one embodiment, the transparent base material is surface-treated to hydrophilize the transparent base material surface. If the transparent substrate is hydrophilized, the processability when coating a composition for forming a transparent conductive layer (metal nanowire dispersion, composition for forming a protective layer) prepared with an aqueous solvent is excellent. Moreover, the transparent conductive film which is excellent in the adhesiveness of a transparent base material and a transparent conductive layer can be obtained.

C-2. Transparent conductive layer The transparent conductive layer includes a metal nanowire or a metal mesh.

(Metal nanowires)
The metal nanowire is a conductive material having a metal material, a needle shape or a thread shape, and a diameter of nanometer. The metal nanowire may be linear or curved. If a transparent conductive layer composed of metal nanowires is used, a transparent conductive film having excellent bending resistance can be obtained. In addition, if a transparent conductive layer composed of metal nanowires is used, the metal nanowires are formed in a mesh shape, so that a good electrical conduction path can be formed even with a small amount of metal nanowires. Can be obtained. Furthermore, when the metal wire has a mesh shape, an opening is formed in the mesh space, and a transparent conductive film having a high light transmittance can be obtained.

The ratio between the thickness d and the length L of the metal nanowire (aspect ratio: L / d) is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 100,000. 10,000. If metal nanowires having a large aspect ratio are used in this way, the metal nanowires can cross well and high conductivity can be expressed by a small amount of metal nanowires. As a result, a transparent conductive film having a high light transmittance can be obtained. In the present specification, the “thickness of the metal nanowire” means the diameter when the cross section of the metal nanowire is circular, and the short diameter when the cross section of the metal nanowire is elliptical. In some cases it means the longest diagonal. The thickness and length of the metal nanowire can be confirmed by a scanning electron microscope or a transmission electron microscope.

The thickness of the metal nanowire is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably 10 nm to 100 nm, and most preferably 10 nm to 50 nm. If it is such a range, a transparent conductive layer with a high light transmittance can be formed.

The length of the metal nanowire is preferably 2.5 μm to 1000 μm, more preferably 10 μm to 500 μm, and particularly preferably 20 μm to 100 μm. If it is such a range, a highly conductive transparent conductive film can be obtained.

As the metal constituting the metal nanowire, any appropriate metal can be used as long as it is a highly conductive metal. The metal nanowire is preferably composed of one or more metals selected from the group consisting of gold, platinum, silver and copper. Among these, silver, copper, or gold is preferable from the viewpoint of conductivity, and silver is more preferable. Alternatively, a material obtained by performing a plating process (for example, a gold plating process) on the metal may be used.

Any appropriate method can be adopted as a method for producing the metal nanowire. For example, a method of reducing silver nitrate in a solution, a method in which an applied voltage or current is applied to the precursor surface from the tip of the probe, a metal nanowire is drawn out at the probe tip, and the metal nanowire is continuously formed, etc. . In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by liquid phase reduction of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Uniformly sized silver nanowires are described in, for example, Xia, Y. et al. etal. , Chem. Mater. (2002), 14, 4736-4745, Xia, Y. et al. etal. , Nano letters (2003) 3 (7), 955-960, mass production is possible.

In the transparent conductive layer, the metal nanowire may be protected by a protective layer.

Any appropriate resin can be used as a material for forming the protective layer. Examples of the resin include acrylic resins; polyester resins such as polyethylene terephthalate; aromatic resins such as polystyrene, polyvinyltoluene, polyvinylxylene, polyimide, polyamide, and polyamideimide; polyurethane resins; epoxy resins; Resin; Acrylonitrile-butadiene-styrene copolymer (ABS); Cellulose; Silicon resin; Polyvinyl chloride; Polyacetate; Polynorbornene; Synthetic rubber; Preferably, polyfunctionality such as pentaerythritol triacrylate (PETA), neopentyl glycol diacrylate (NPGDA), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane triacrylate (TMPTA), etc. A curable resin composed of acrylate (preferably an ultraviolet curable resin) is used.

The protective layer may be made of a conductive resin. Examples of the conductive resin include poly (3,4-ethylenedioxythiophene) (PEDOT), polyaniline, polythiophene, and polydiacetylene.

The protective layer may be made of an inorganic material. As the inorganic materials, for example, silica, mullite, _{alumina, SiC, MgO-Al 2 O} 3 -SiO 2, Al 2 O 3 -SiO 2, MgO-Al 2 O 3 -SiO 2 -Li 2 O , and the like .

The transparent conductive layer may be formed by applying a dispersion liquid (metal nanowire dispersion liquid) obtained by dispersing the metal nanowires in a solvent on the transparent substrate, and then drying the coating layer. it can.

Examples of the solvent contained in the metal nanowire dispersion liquid include water, alcohol solvents, ketone solvents, ether solvents, hydrocarbon solvents, and aromatic solvents. From the viewpoint of reducing the environmental load, it is preferable to use water.

The dispersion concentration of the metal nanowires in the metal nanowire dispersion liquid is preferably 0.1% by weight to 1% by weight. If it is such a range, the transparent conductive layer which is excellent in electroconductivity and light transmittance can be formed.

The metal nanowire dispersion may further contain any appropriate additive depending on the purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of the metal nanowires, and a surfactant that prevents aggregation of the metal nanowires. The type, number and amount of additives used can be appropriately set according to the purpose. In addition, the metal nanowire dispersion liquid may contain any appropriate binder resin as necessary as long as the effects of the present invention are obtained.

Any appropriate method can be adopted as a method of applying the metal nanowire dispersion. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, slot die coating, letterpress printing method, intaglio printing method, and gravure printing method. Any appropriate drying method (for example, natural drying, air drying, heat drying) can be adopted as a method for drying the coating layer. For example, in the case of heat drying, the drying temperature is typically 100 ° C. to 200 ° C., and the drying time is typically 1 to 10 minutes.

When the transparent conductive layer has a protective layer, for example, after forming the metal nanowire portion as described above, the protective layer further includes the protective layer forming material or the precursor of the protective layer forming material (the resin Can be formed by applying a composition for forming a protective layer containing the monomer), followed by drying and, if necessary, curing treatment. As a coating method, a method similar to that of the dispersion liquid can be adopted. Any appropriate drying method (for example, natural drying, air drying, heat drying) may be employed as the drying method. For example, in the case of heat drying, the drying temperature is typically 100 ° C. to 200 ° C., and the drying time is typically 1 to 10 minutes. The curing treatment can be performed under any appropriate condition depending on the resin constituting the protective layer.

The protective layer forming composition may contain a solvent. Examples of the solvent contained in the protective layer forming composition include alcohol solvents, ketone solvents, tetrahydrofuran, hydrocarbon solvents, and aromatic solvents. Preferably the solvent is volatile. The boiling point of the solvent is preferably 200 ° C. or lower, more preferably 150 ° C. or lower, and further preferably 100 ° C. or lower.

The composition for forming a protective layer may further contain any appropriate additive depending on the purpose. Examples of the additive include a crosslinking agent, a polymerization initiator, a stabilizer, a surfactant, and a corrosion inhibitor.

When the transparent conductive layer includes metal nanowires, the thickness of the transparent conductive layer is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 3 μm, and particularly preferably 0.1 μm to 1 μm. It is. If it is such a range, the transparent conductive film excellent in electroconductivity and light transmittance can be obtained.

When the transparent conductive layer contains metal nanowires, the total light transmittance of the transparent conductive layer is preferably 85% or more, more preferably 90% or more, and further preferably 95% or more.

The content ratio of the metal nanowires in the transparent conductive layer is preferably 30% by weight to 96% by weight and more preferably 43% by weight to 88% by weight with respect to the total weight of the transparent conductive layer. If it is such a range, the transparent conductive film excellent in electroconductivity and light transmittance can be obtained.

When the metal nanowire is a silver nanowire, the density of the transparent conductive layer is preferably 1.3 g / cm ³ to 7.4 g / cm ³ , more preferably 1.6 g / cm ³ to 4.8 g / cm ³ . If it is such a range, the transparent conductive film excellent in electroconductivity and light transmittance can be obtained.

(Metal mesh)
The transparent conductive layer containing a metal mesh is formed by forming fine metal wires in a lattice pattern on the transparent substrate. The transparent conductive layer containing a metal mesh can be formed by any appropriate method. The transparent conductive layer is formed, for example, by applying a photosensitive composition (a composition for forming a transparent conductive layer) containing a silver salt on the laminate, and then performing an exposure process and a development process to form a predetermined thin metal wire. It can obtain by forming in the pattern of. The transparent conductive layer can also be obtained by printing a paste containing metal fine particles (a composition for forming a transparent conductive layer) in a predetermined pattern. Details of such a transparent conductive layer and a method for forming the transparent conductive layer are described in, for example, Japanese Patent Application Laid-Open No. 2012-18634, and the description thereof is incorporated herein by reference. Another example of the transparent conductive layer composed of a metal mesh and a method for forming the transparent conductive layer includes a transparent conductive layer and a method for forming the transparent conductive layer described in JP-A-2003-331654.

When the transparent conductive layer includes a metal mesh, the thickness of the transparent conductive layer is preferably 0.1 μm to 30 μm, more preferably 0.1 μm to 9 μm, and further preferably 1 μm to 3 μm. .

When the transparent conductive layer contains a metal mesh, the transmittance of the transparent conductive layer is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more.

The transparent conductive layer can be patterned into a predetermined pattern. The shape of the pattern of the transparent conductive layer is preferably a pattern that operates well as a touch panel (for example, a capacitive touch panel). For example, JP 2011-511357 A, JP 2010-164938 A, and JP 2008-A No. 310550, JP-T 2003-511799, JP-T 2010-541109, and the like. After the transparent conductive layer is formed on the transparent substrate, it can be patterned using a known method. In this invention, it can prevent that the pattern of the transparent conductive layer patterned in this way is visually recognized.

C-3. Other layer The said transparent conductive film may be equipped with arbitrary appropriate other layers as needed. Examples of the other layers include a hard coat layer, an antistatic layer, an antiglare layer, an antireflection layer, and a color filter layer.

The hard coat layer has a function of imparting chemical resistance, scratch resistance and surface smoothness to the transparent substrate.

Any appropriate material can be adopted as the material constituting the hard coat layer. Examples of the material constituting the hard coat layer include an epoxy resin, an acrylic resin, a silicone resin, and a mixture thereof. Among these, an epoxy resin excellent in heat resistance is preferable. The hard coat layer can be obtained by curing these resins with heat or active energy rays.

D. In one embodiment of the image display device, an image display device using the laminate of the present invention is provided. FIG. 2 is a schematic cross-sectional view showing an example of an image display device using the laminate of the present invention. The image display device 200 includes a stacked body 100 and a display element 110 in order from the viewing side. As described above, the laminate 100 includes the circularly polarizing plate 10 and the transparent conductive film 20 in order from the viewing side. The circularly polarizing plate includes a polarizer 11, a first retardation layer 12, and a second retardation layer 13 in order from the viewing side. The transparent conductive film 20 has a transparent substrate 21 and a transparent conductive layer 22 disposed on at least one side of the transparent substrate 21. The transparent conductive film 20 includes the metal nanowire 1 or a metal mesh. The transparent conductive film 20 can function as, for example, an electrode of a touch panel, an electromagnetic wave shield, or the like in an image display device. As the display element 110, a display element including a metal reflector is used. A typical example of such a display element is an organic EL element including a reflective electrode (reflector). If an organic EL element is used as the display element, an image display device having excellent flexibility can be obtained. In addition, the transparent conductive film 20, the circularly polarizing plate 10, and / or the display element 110 can be bonded together via arbitrary appropriate adhesives (not shown). In addition, the image display device of the present invention may further include any appropriate other member depending on the application or the like.

In the image display device using the laminate of the present invention, the circularly polarizing plate is disposed closer to the viewing side than the transparent conductive film containing metal nanowires or metal meshes, thereby reflecting light from the reflector of the display element, And the reflected light from a metal nanowire or a metal mesh is reduced. Originally, metal nanowires or metal meshes cause an increase in reflectivity. According to the present invention, even if metal nanowires or metal meshes are included, an increase in reflectivity due to the metal nanowires or metal meshes can be suppressed. . As a result, the difference in light intensity between the external light reflected by the metal nanowire or metal mesh and the external light reflected by a portion other than the metal nanowire or metal mesh is reduced, and the conductive pattern (ie, the metal nanowire or metal mesh pattern) is recognized. It is possible to obtain an image display device that is difficult to perform.

Preferably, the diffuse reflectance is reduced by 90% or more in the laminated portion of the circularly polarizing plate and the transparent conductive film in the image display device of the present invention. Thus, the diffuse reflectance is reduced because the laminate composed of the circularly polarizing plate and the transparent conductive film is placed on an aluminum reflector for evaluation, and predetermined light is incident and reflected. Quantitative evaluation can be made based on the relationship between the diffuse reflectance A when measured by the above and the diffuse reflectance B measured when the light is incident and reflected on the aluminum reflector. In the present specification, when the diffuse reflectance A and the diffuse reflectance B have a relationship of A ≦ (100% −X%) × B, “the circularly polarizing plate and the transparent conductive film in the image display device” In the laminated portion, the diffuse reflectance is reduced by X% or more. ” The relationship between the diffuse reflectance A and the diffuse reflectance B is preferably A ≦ 0.1B. Further, the relationship between the diffuse reflectance A and the diffuse reflectance B is more preferably A ≦ 0.05B, further preferably A ≦ 0.03B, and particularly preferably A ≦ 0.01B. That is, in the laminated portion of the circularly polarizing plate and the transparent conductive film in the image display device of the present invention, the diffuse reflectance is more preferably 95% or more, more preferably 97% or more, It is particularly preferable that the reduction is 99% or more. Thus, the image display apparatus in which the scattering reflection is reduced can be obtained by arranging a circularly polarizing plate on the viewing side from the display element including the reflector and the transparent conductive film. A method for measuring the diffuse reflectance will be described later.

The difference (A−C) between the diffuse reflectance A and the diffuse reflectance C measured by placing only the circularly polarizing plate on the aluminum reflector with the polarizer facing outside is preferably 0. It is 17% or less, more preferably 0.15% or less, and still more preferably 0.01% to 0.12%. A small (AC) means that an increase in reflectance due to the metal nanowire or the metal mesh is suppressed.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The evaluation methods in the examples are as follows. The thickness was measured using a digital gauge cordless type “DG-205” manufactured by Ozaki Seisakusho Co., Ltd.

(1) Retardation value A sample of 50 mm × 50 mm was cut out from each retardation layer, used as a measurement sample, and measured using Axoscan manufactured by Axometrics. The measurement wavelength was 550 nm and the measurement temperature was 23 ° C.
Moreover, the average refractive index was measured using an Abbe refractometer manufactured by Atago Co., Ltd., and the refractive indexes nx, ny, and nz were calculated from the obtained retardation values.
(2) Surface resistance value It measured using the product name "EC-80" made from NAPSON. The measurement temperature was 23 ° C.
(3) Total light transmittance, haze Measured at 23 ° C. using a trade name “HR-100” manufactured by Murakami Color Research Laboratory. The average value of 3 repetitions was taken as the measured value.
(4) Diffuse Reflectance Using a trade name “CM-2600d” manufactured by Konica Minolta, measurement was carried out by a D65 light source in a non-regular (SCE) method. The measurement temperature was 23 ° C. The average value of 2 repetitions was taken as the measured value.
In Examples and Comparative Examples, the diffuse reflectance A measured by placing a laminate composed of a circularly polarizing plate and a transparent conductive film on an aluminum reflector, and the metal nanowire from the transparent conductive film of the laminate The diffuse reflectance A ′ measured after removing was measured.

[Example 1]
(Preparation of first retardation layer)
A stretched film (1) to be the first retardation layer was produced as follows.
A norbornene-based cycloolefin film (trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.) was stretched in a uniaxial direction so that the in-plane retardation Re (550) was 140 nm to obtain a stretched film (1). The thickness direction retardation Rth (550) of the film (1) was 141 nm, and the film (1) exhibited refractive index characteristics of nx> ny = nz.

(Preparation of second retardation layer)
20 parts by weight of a side chain type liquid crystal polymer represented by the following chemical formula (I) (numbers 65 and 35 in the formula indicate mol% of the monomer units and are represented by block polymer for convenience: weight average molecular weight 5000), Dissolve 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Palicolor LC242) and 5 parts by weight of a photopolymerization initiator (trade name: Irgacure 907, manufactured by Ciba Specialty Chemicals) in 200 parts by weight of cyclopentanone. Thus, a liquid crystal coating solution was prepared. And after apply | coating the said coating liquid to a base film (norbornene-type resin film: Nippon Zeon Co., Ltd. make, brand name "ZEONEX") with a bar coater, a liquid crystal is dried by heating at 80 degreeC for 4 minutes. Oriented. The liquid crystal layer was irradiated with ultraviolet rays to cure the liquid crystal layer, thereby forming a liquid crystal solidified layer (thickness: 0.58 μm) serving as the second retardation layer on the substrate. The in-plane retardation Re (550) of this layer is 0 nm, the thickness direction retardation Rth (550) is −71 nm (nx: 1.5326, ny: 1.5326, nz: 1.6550), and nz> The refractive index characteristic of nx = ny was shown.

(Production of circularly polarizing plate)
After the liquid crystal solidified layer (second retardation layer) is bonded to the stretched film (1) (first retardation layer) via an acrylic adhesive, the base film is removed. A laminated retardation film in which the liquid crystal solidified layer was transferred to the stretched film (1) was obtained. The in-plane retardation Re (550) of the obtained laminated retardation film was 141 nm, and the thickness direction retardation Rth (550) was 70 nm.
Next, the stretched film (1) (first retardation layer) and a linear polarizer (manufactured by Nitto Denko Corporation, trade name “polarizing plate SEG1425”) having an adhesive layer are bonded together to form a circularly polarizing plate ( 1) was obtained. The stretched film (1) and the linear polarizer were bonded together so that the slow axis of the stretched film (1) was 45 ° counterclockwise with respect to the absorption axis of the linear polarizer.

(Synthesis of silver nanowire and preparation of silver nanowire dispersion)
In a reaction vessel equipped with a stirrer, at 160 ° C., 5 ml of anhydrous ethylene glycol and 0.5 ml of an anhydrous ethylene glycol solution of PtCl ₂ (concentration: 1.5 × 10 ⁻⁴ mol / L) were added. After 4 minutes, the obtained solution was mixed with 2.5 ml of an anhydrous ethylene glycol solution (concentration: 0.12 mol / l) of AgNO ₃ and an anhydrous ethylene glycol solution (concentration: 0.36 mol) of polyvinylpyrrolidone (MW: 5500). / L) 5 ml was dropped at the same time over 6 minutes to produce silver nanowires. This dropping was performed at 160 ° C. until AgNO ₃ was completely reduced. Then, acetone is added to the reaction mixture containing silver nanowires obtained as described above until the volume of the reaction mixture becomes 5 times, and then the reaction mixture is centrifuged (2000 rpm, 20 minutes), Silver nanowires were obtained.
The obtained silver nanowires had a minor axis of 30 nm to 40 nm, a major axis of 30 nm to 50 nm, and a length of 30 μm to 50 μm.
The silver nanowire (concentration: 0.2 wt%) and dodecyl-pentaethylene glycol (concentration: 0.1 wt%) were dispersed in pure water to prepare a silver nanowire dispersion.

(Preparation of protective layer forming composition)
A mixture of isopropyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) and diacetone alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) at a weight ratio of 1: 1 was used as a solvent. In the solvent, dipentaerythritol hexaacrylate (DPHA) (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “A-DPH”) 3.0% by weight, and photoinitiator (Ciba Japan Co., Ltd., product name “Irgacure 907” )) 0.09 wt% was added to prepare a protective layer forming composition.

(Preparation of transparent conductive film (1))
A norbornene-based cycloolefin film (manufactured by Nippon Zeon Co., Ltd., trade name “Zeonor”, in-plane retardation Re = 1.7 nm, thickness direction retardation Rth = 1.8 nm) was used as a transparent substrate.
On this transparent base material, the said silver nanowire dispersion liquid was apply | coated using the bar coater (the product name "Bar Coater No. 10" by Daiichi Science Co., Ltd.), and it was made to dry for 2 minutes within a 120 degreeC ventilation dryer. . Then, the said protective layer formation composition was apply | coated with the slot die by 4 micrometers of wet film thickness, and was dried for 2 minutes within the 120 degreeC ventilation drying machine. Next, the protective layer-forming composition is cured by irradiating ultraviolet light with an integrated illuminance of 400 mJ / cm ² with an ultraviolet light irradiation device (Fusion UV Systems) having an oxygen concentration of 100 ppm to form a protective layer, and transparent conductive Film (1) [transparent substrate / transparent conductive layer (including metal nanowires and protective layer)] was obtained.
This transparent conductive film (1) had a surface resistance value of 151 Ω / □, a total light transmittance of 91.4%, and a haze of 2.0%.

(Measurement of diffuse reflectance A)
The said circularly-polarizing plate (1) and the said transparent conductive film (1) were bonded together through the translucent adhesive (Nitto Denko Co., Ltd. make, brand name "CS9662"), and the laminated body I was obtained. At this time, the second retardation layer of the circularly polarizing plate (1) and the transparent conductive layer of the transparent conductive film (1) were bonded to face each other. Further, the laminate I was placed on an aluminum reflector such that the circularly polarizing plate was on the outside (incident side of external light), and the diffuse reflectance A was measured according to the method (4). The results are shown in Table 2.
Separately, when the diffuse reflectance B of the aluminum reflector alone was measured according to the method of (4) above, the diffuse reflectance B was 59.16%.

(Measurement of diffuse reflectance A ′)
The transparent conductive film (1) was etched to remove metal nanowires. The etching treatment was performed by immersing the transparent conductive film (1) in an etchant (product name “mixed acid Al etching solution” manufactured by Kanto Chemical Co., Inc.) heated to 40 ° C. for 15 seconds. The surface resistance value of the film after the etching treatment was not less than the measurement upper limit (1,500Ω / □) of the apparatus, the total light transmittance was 92.1%, and the haze was 1.7%.
The circularly polarizing plate (1) and the film after the etching treatment were bonded to each other via a translucent adhesive (manufactured by Nitto Denko Corporation, trade name “CS9662”) to obtain a laminate I ′. At this time, the second retardation layer of the circularly polarizing plate (1) was bonded to face the protective layer of the film after the etching treatment. Further, the laminate I ′ was placed on an aluminum reflector (diffuse reflectance B: 59.16%) so that the circularly polarizing plate was on the outer side, and the diffuse reflectance A ′ was according to the method of (4) above. Was measured. The results are shown in Table 2.

[Example 2]
(Production of circularly polarizing plate)
In the same manner as in Example 1, a first retardation layer and a second retardation layer were produced, and a circularly polarizing plate was further produced.

(Preparation of transparent conductive film (2))
A norbornene-based cycloolefin film (manufactured by Nippon Zeon Co., Ltd., trade name “Zeonor”, in-plane retardation Re = 1.7 nm, thickness direction retardation Rth = 1.8 nm) was used as a transparent substrate. The surface of the norbornene-based cycloolefin film was subjected to corona treatment to make the surface hydrophilic.
Thereafter, a metal mesh was formed on one side of the norbornene-based cycloolefin film by a screen printing method using a silver paste (trade name “RA FS 039” manufactured by Toyochem Co., Ltd.) (line width: 8.5 μm, pitch) Sintered at 120 ° C. for 10 minutes to obtain a transparent conductive film (2) [transparent substrate / transparent conductive layer (including metal mesh)].
The transparent conductive film had a surface resistance value of 155Ω / □, a total light transmittance of 88.1%, and a haze of 7.0%.

(Measurement of diffuse reflectance A)
A laminate II was obtained in the same manner as in Example 1 except that the transparent conductive film (2) was used instead of the transparent conductive film (1), and the diffuse reflectance A was measured for the laminate II. The results are shown in Table 2.

(Measurement of diffuse reflectance A ′)
The transparent conductive film (2) was etched to remove the metal mesh. The etching treatment was performed by immersing the transparent conductive film in an etchant (product name “mixed acid Al etching solution” manufactured by Kanto Chemical Co., Inc.) heated to 40 ° C. for 15 seconds. The surface resistance value of the film after the etching treatment was not less than the measurement upper limit (1,500Ω / □) of the apparatus, the total light transmittance was 92.4%, and the haze was 0.7%.
The scattering reflectance A ′ was measured in the same manner as in Example 1 for the film after the etching treatment. The results are shown in Table 2.

[Example 3]
(Production of polycarbonate resin film)
37.5 parts by weight of isosorbide (ISB), 91.5 parts by weight of 9,9- [4- (2-hydroxyethoxy) phenyl] fluorene (BHEPF), 8.4 parts by weight of polyethylene glycol (PEG) having an average molecular weight of 400, First, 105.7 parts by weight of diphenyl carbonate (DPC) and 0.594 parts by weight of cesium carbonate (0.2% by weight aqueous solution) as a catalyst were put into a reaction vessel, respectively, and the first stage of the reaction in a nitrogen atmosphere. In this step, the temperature of the heat medium in the reaction vessel was set to 150 ° C., and the raw materials were dissolved while stirring as necessary (about 15 minutes).

Next, the pressure in the reaction vessel was changed from normal pressure to 13.3 kPa, and the generated phenol was extracted out of the reaction vessel while the temperature of the heat medium in the reaction vessel was increased to 190 ° C. over 1 hour.
After holding the reaction vessel temperature at 190 ° C. for 15 minutes, as a second step, the pressure in the reaction vessel is set to 6.67 kPa, and the heat medium temperature of the reaction vessel is increased to 230 ° C. in 15 minutes. The generated phenol was extracted out of the reaction vessel. Since the stirring torque of the stirrer increased, the temperature was raised to 250 ° C. in 8 minutes, and the pressure in the reaction vessel was reduced to 0.200 kPa or less in order to remove the generated phenol. After reaching a predetermined stirring torque, the reaction was terminated, and the formed reaction product was extruded into water, and then pelletized to obtain BHEPF / ISB / PEG = 42.9 mol% / 52.8 mol% / 4.3. A polycarbonate-based resin A containing a structural unit derived from a dihydroxy compound at a mol% ratio was obtained.
The obtained polycarbonate resin A had a glass transition temperature of 126 ° C. and a reduced viscosity of 0.372 dL / g.

The obtained polycarbonate-based resin A was vacuum-dried at 80 ° C. for 5 hours, and then a single-screw extruder (made by Isuzu Chemical Industries, screw diameter 25 mm, cylinder set temperature: 220 ° C.), T die (width 300 mm, set temperature) : 220 ° C.), a film forming apparatus equipped with a chill roll (set temperature: 120 to 130 ° C.) and a winder, a polycarbonate resin film having a length of 3 m, a width of 300 mm and a thickness of 120 μm was produced.
The obtained polycarbonate resin film had a water absorption rate of 1.2%.

(Preparation of first retardation layer)
The obtained polycarbonate-based resin film was cut into a length of 300 mm and a width of 300 mm, and longitudinally stretched at a temperature of 136 ° C. and a magnification of 2 times using a lab stretcher KARO IV (manufactured by Bruckner), and a stretched film (2) Got.
Re (550) of the obtained stretched film (2) is 141 nm, Rth (550) is 141 nm (nx: 1.5969, ny: 1.5942, nz: 1.5942), and nx> ny = nz. Refractive index characteristics are shown. Moreover, Re (450) / Re (550) of the obtained stretched film (2) was 0.89.

(Production of circularly polarizing plate)
A circularly polarizing plate (2) was obtained in the same manner as in Example 1 except that the stretched film (2) was used as the first retardation layer. The in-plane retardation Re (550) of the laminated retardation film composed of the first retardation layer and the second retardation layer is 141 nm, and the thickness direction retardation Rth (550) is 70 nm. there were.

(Preparation of transparent conductive film)
A transparent conductive film was obtained in the same manner as Example 1.

(Measurement of diffuse reflectance A, A ')
A laminate was prepared in the same manner as in Example 1 except that the circularly polarizing plate (2) was used instead of the circularly polarizing plate (1), and the diffuse reflectances A and A ′ were measured. The results are shown in Table 2.

[Example 4]
A circularly polarizing plate, a conductive film and a laminate were produced as in Example 2 except that the stretched film (2) produced in Example 3 was used as the first retardation layer, and diffuse reflectance A , A ′ was measured. The results are shown in Table 2.

[Comparative Example 1]
Example 1 except that a circularly polarizing plate produced without using the second retardation layer, that is, a circularly polarizing plate having only the stretched film (1) (first retardation layer) was used as the retardation layer. A laminate was prepared in the same manner as described above, and the diffuse reflectances A and A ′ were measured. The results are shown in Table 2.

[Comparative Example 2]
Example 2 except that a circularly polarizing plate produced without using the second retardation layer, that is, a circularly polarizing plate having only the stretched film (1) (first retardation layer) was used as the retardation layer. A laminate was prepared in the same manner as described above, and the diffuse reflectances A and A ′ were measured. The results are shown in Table 2.

Table 1 summarizes the configurations used for the measurement of diffuse reflectance A in Examples 1 to 4 and Comparative Examples 1 and 2.

[Supplement under rule 26 13.08.2015]

As is apparent from Table 1, the diffuse reflectance A is reduced when the laminate of the present invention is used. In the image display device including the laminate according to the present invention, the intensity of the external light reflected on the metal nanowire is low, and the difference in light intensity between the external light reflected on the metal nanowire and the external light reflected on a portion other than the metal nanowire is small. The conductive pattern is difficult to see. Moreover, since there is little external light reflection, contrast is high.

DESCRIPTION OF SYMBOLS 1 Metal nanowire 2 Protective layer 10 Circularly polarizing plate 11 Polarizer 12 1st phase difference film 13 2nd phase difference film 20 Transparent conductive film 21 Transparent base material 22 Transparent conductive layer

Claims (9)

1. A laminate comprising a circularly polarizing plate and a transparent conductive film,
   The circularly polarizing plate has a polarizer, a first retardation layer, and a second retardation layer in order from the surface opposite to the transparent conductive film,
   The first retardation layer exhibits a refractive index characteristic of nx> ny ≧ nz;
   The second retardation layer exhibits a refractive index characteristic of nz> nx ≧ ny,
   The in-plane retardation Re (550) of the laminated retardation film composed of the first retardation layer and the second retardation layer is 120 nm to 160 nm, and the thickness direction retardation Rth (550) is 40 nm. ~ 100nm,
   The transparent conductive film has a transparent base material and a transparent conductive layer disposed on at least one side of the transparent base material,
   The in-plane retardation Re of the transparent substrate is 1 nm to 100 nm,
   The transparent conductive layer comprises metal nanowires or metal mesh;
   Laminated body.
2. The laminate according to claim 1, wherein the laminated retardation film does not contain an optically anisotropic layer other than the first retardation layer and the second retardation layer.
3. The laminate according to claim 1, wherein an in-plane retardation of the first retardation layer satisfies a relationship of Re (450) <Re (550).
4. The laminate according to claim 1, wherein the water absorption of the first retardation layer is 3% or less.
5. The laminate according to claim 1, wherein the first retardation layer is obtained by oblique stretching.
6. The laminate according to claim 1, wherein the transparent conductive layer is patterned.
7. The laminate according to claim 1, wherein the metal nanowire is composed of one or more metals selected from the group consisting of gold, platinum, silver, and copper.
8. An image display device comprising the laminate according to claim 1 and a metal reflector in order from the viewing side.
9. The image display device according to claim 8, wherein the diffuse reflectance is reduced by 90% or more in a laminated portion of the circularly polarizing plate and the transparent conductive film in the image display device.
   

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