CN109307901B

CN109307901B - Optical laminate with touch sensor layer, image display device, and method for manufacturing optical laminate

Info

Publication number: CN109307901B
Application number: CN201810840974.9A
Authority: CN
Inventors: 今野芳美; 伊崎章典; 柳沼宽教; 北村吉绍; 形见普史; 山本真也
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2017-07-28
Filing date: 2018-07-27
Publication date: 2022-04-01
Anticipated expiration: 2038-07-27
Also published as: CN109307901A

Abstract

The invention provides an optical laminate with a touch sensor layer, which can inhibit the increase of thickness and the change of color according to the angle of polarized sunglasses, and consequently can improve the visibility. The optical laminate is formed by laminating a touch sensor layer, a second phase difference layer, a polarizer and a third phase difference layer in this order from a viewing side, wherein the touch sensor layer comprises a first phase difference layer and a transparent conductive layer disposed on one side or both sides of the first phase difference layer, and wherein the touch sensor layer and the second phase difference layer are laminated via an adhesive layer having an ultraviolet absorbing function.

Description

Optical laminate with touch sensor layer, image display device, and method for manufacturing optical laminate

Technical Field

The present invention relates to an optical laminate with a touch sensor layer, an image display device, and a method for manufacturing the optical laminate.

Background

In order to improve visibility when viewing a display screen of an image display device with polarized sunglasses, there is known an image display device using an 1/4 wavelength plate as a protective base material of a viewing side polarizing plate (patent document 1). The image display device of patent document 1 has an 1/4-wavelength plate on the viewing side of the viewing-side polarizing plate, and the angle formed by the absorption axis of the viewing-side polarizing plate and the slow axis of the 1/4-wavelength plate is set to 45 °. As a result, the problem that the display screen becomes dark when the display screen is observed in a state where the transmission axis of the polarized sunglasses is orthogonal to the transmission axis of the viewing-side polarizer can be solved.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 10-10523

Disclosure of Invention

Problems to be solved by the invention

In the conventional image display device, when a display screen is viewed by wearing polarized sunglasses, there is a problem that a hue change and a transmittance change occur depending on an angle of the polarized sunglasses, and visibility is degraded.

In addition, in recent years, image display devices having a touch sensor function have become widespread, but thinning is generally demanded as a general requirement for the entire image display devices.

The present invention has been made to solve the above conventional problems, and has as its main object: provided are an optical laminate with a touch sensor layer, an image display device provided with the optical laminate, and a method for manufacturing the optical laminate, wherein the optical laminate can suppress a change in hue according to the angle of polarized sunglasses while suppressing an increase in thickness, and as a result, the visibility can be improved.

Means for solving the problems

The optical laminate of the present invention is formed by laminating a touch sensor layer, a second phase difference layer, a polarizer, and a third phase difference layer in this order from a viewing side, wherein the touch sensor layer includes a first phase difference layer and a transparent conductive layer disposed on one side or both sides of the first phase difference layer, and wherein the touch sensor layer and the second phase difference layer are laminated via an adhesive layer having an ultraviolet absorbing function.

In one embodiment, the in-plane retardation Re1 of the first retardation layer satisfies Re1(450)/Re1(550) < 1.03, Re1(650)/Re1(550) > 0.97,

the in-plane retardation Re2 of the second retardation layer satisfies Re2(450)/Re2(550) of not less than 1.03 and Re2(650)/Re2(550) of not more than 0.97.

(wherein Re1(450) and Re2(450) represent in-plane retardation measured at 23 ℃ with light having a wavelength of 450nm, Re1(550) and Re2(550) represent in-plane retardation measured at 23 ℃ with light having a wavelength of 550nm, and Re1(650) and Re2(650) represent in-plane retardation measured at 23 ℃ with light having a wavelength of 650 nm.)

In one embodiment, the in-plane retardation Re1(550) of the first retardation layer is 105 to 115nm, the in-plane retardation Re2(550) of the second retardation layer is 190 to 260nm, the angle θ 1 between the absorption axis of the polarizer and the slow axis of the first retardation layer is 19 to 35 °, the angle θ 2 between the absorption axis of the polarizer and the slow axis of the second retardation layer is 77 to 85 °,

or the in-plane retardation Re1(550) of the first retardation layer is 116nm to 125nm, the in-plane retardation Re2(550) of the second retardation layer is 200nm to 260nm, the angle theta 1 formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 DEG to 35 DEG, the angle theta 2 formed by the absorption axis of the polarizer and the slow axis of the second retardation layer is 75 DEG to 85 DEG,

or the in-plane retardation Re1(550) of the first retardation layer is 126 to 135nm, the in-plane retardation Re2(550) of the second retardation layer is 210 to 260nm, the angle theta 1 formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 to 35 DEG, and the angle theta 2 formed by the absorption axis of the polarizer and the slow axis of the second retardation layer is 75 to 85 DEG,

or the in-plane retardation Re1(550) of the first retardation layer is 136nm to 145nm, the in-plane retardation Re2(550) of the second retardation layer is 220nm to 270nm, the angle theta 1 formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 DEG to 31 DEG, and the angle theta 2 formed by the absorption axis of the polarizer and the slow axis of the second retardation layer is 75 DEG to 83 deg.

In one embodiment, the first retardation layer is formed of a stretched polymer film, and the second retardation layer is formed of an oriented cured layer of a liquid crystal compound.

the in-plane retardation Re2 of the second retardation layer satisfies Re2(450)/Re2(550) < 1.03 and Re2(650)/Re2(550) > 0.97.

In one embodiment, the refractive index ellipsoid of the first retardation layer satisfies nx > nz > ny, and the refractive index ellipsoid of the second retardation layer satisfies nx > ny > nz.

In one embodiment, the refractive index ellipsoid of the first retardation layer satisfies nx > ny ═ nz, and the refractive index ellipsoid of the second retardation layer satisfies nx ═ nz > ny.

In one embodiment, the adhesive layer having an ultraviolet absorbing function has an average light transmittance of 5% or less at a wavelength of 300 to 400nm, an average light transmittance of 70% or more at a wavelength of 450 to 500nm, and an average light transmittance of 80% or more at a wavelength of 500 to 780 nm.

According to another aspect of the present invention, an image display apparatus is provided. An image display device of the present invention includes the optical laminate.

According to still another aspect of the present invention, there is provided a method for producing the optical laminate. The method for producing an optical laminate of the present invention comprises the steps of: the touch sensor layer is formed by continuously bonding a first long film constituting the touch sensor layer, a second long film constituting the second phase difference layer, the polarizer, and a third long film constituting the third phase difference layer to adjacent films while conveying them.

Effects of the invention

According to the present invention, by laminating the first retardation layer and the second retardation layer on the viewing side of the polarizer, a change in hue according to the angle of the polarized sunglasses when the polarized sunglasses are worn and a display screen is viewed is suppressed, and as a result, the visibility can be improved. Further, by causing the first retardation layer to function also as a base material of the touch sensor layer, the thickness can be reduced as compared with a case where another touch sensor layer is laminated in addition to the first retardation layer and the second retardation layer. Further, the effect of ultraviolet rays on an image display panel such as a liquid crystal panel is increased by reducing the thickness, but in the present invention, since the touch sensor layer and the second phase difference layer are laminated via the adhesive agent layer having an ultraviolet absorption function, the image display panel can be suitably protected from ultraviolet rays.

Drawings

Fig. 1 is a schematic cross-sectional view showing an optical layered body according to an embodiment of the present invention.

Figure 2 is a schematic cross-sectional view of an optical stack according to another embodiment of the present disclosure.

Fig. 3 is a diagram showing hues obtained by transmittance spectrum measurement performed with the optical layered body of example 1, comparative example 1, and comparative example 2 interposed therebetween.

Fig. 4 is a graph showing the change in transmittance measured by the transmittance spectrum through the optical layered body of example 1, comparative example 1, and comparative example 2.

Description of the symbols

10 touch sensor layer

12 first phase difference layer

14 transparent conductive layer

20 adhesive layer having ultraviolet absorbing function

30 second phase difference layer

40 polarizer

50 third phase difference layer

60 fourth phase difference layer

100 optical stack

Detailed Description

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

(definitions of terms and symbols)

The terms and symbols in the present specification are defined as follows.

(1) Refractive index (nx, ny, nz)

"nx" is a refractive index in a direction in which the in-plane refractive index is maximum (i.e., slow axis direction), "ny" is a refractive index in a direction orthogonal to the slow axis in the plane (i.e., fast axis direction), and "nz" is a refractive index in the thickness direction.

(2) In-plane retardation (Re)

"Re (. lamda)" is an in-plane retardation measured at 23 ℃ with light having a wavelength of. lamda.nm. For example, "Re (550)" is an in-plane retardation measured at 23 ℃ with light having a wavelength of 550 nm. Re (λ) is obtained by the formula Re (λ) ═ nx-ny × d when the thickness of the layer (film) is d (nm).

(3) Retardation in thickness direction (Rth)

"Rth (λ)" is a phase difference in the thickness direction measured at 23 ℃ with light having a wavelength of λ nm. For example, "Rth (550)" is a phase difference in the thickness direction measured at 23 ℃ with light having a wavelength of 550 nm. Rth (λ) is obtained from the expression Rth (λ) ═ nx-nz × d when the thickness of the layer (film) is d (nm).

(4) Coefficient of Nz

The Nz coefficient is obtained from Nz ═ Rth/Re.

A. Integral construction of optical laminate

Figure 1 is a schematic cross-sectional view of an optical stack according to one embodiment of the present invention. The optical layered body 100a has a structure in which a touch sensor layer 10, a second retardation layer 30, a polarizer 40, and a third retardation layer 50 are sequentially layered. The touch sensor layer 10 includes a first retardation layer 12 and a transparent conductive layer 14, and the transparent conductive layer 14 is disposed on one side of the first retardation layer 12. The touch sensor layer 10 is laminated with the second retardation layer 30 via the adhesive layer 20. Although not shown, the other layers are typically laminated via an arbitrary appropriate adhesive layer (e.g., an adhesive layer or an adhesive layer). In the illustrated example, the touch sensor layer 10 is disposed so that the transparent conductive layer 14 is on the second retardation layer 30 side, but the configuration is not limited to this, and the touch sensor layer may be disposed so that the first retardation layer 12 is on the second retardation layer 30 side.

The optical layered body 100a typically uses an image display device (typically, a liquid crystal display device or an organic EL display device). The optical laminate 100a is disposed on the image display device so that the touch sensor layer 10 is visible. That is, in a state where the optical laminate 100a is disposed in the image display device, the touch sensor layer 10, the second retardation layer 30, the polarizer 40, and the third retardation layer 50 are disposed in this order from the viewing side of the image display device.

In one embodiment, the first retardation layer exhibits a flat wavelength dispersion characteristic in which the in-plane retardation value hardly changes regardless of the wavelength of the measurement light, and the second retardation layer exhibits a positive wavelength dispersion characteristic in which the in-plane retardation value becomes smaller as the wavelength of the measurement light becomes larger. The in-plane retardation Re1 of the first retardation layer and the in-plane retardation Re2 of the second retardation layer preferably satisfy the following formulas (1) to (4).

Re1(450)/Re1(550)＜1.03 (1)

Re1(650)/Re1(550)＞0.97 (2)

Re2(450)/Re2(550)≥1.03 (3)

Re2(650)/Re2(550)≤0.97 (4)

When the first retardation layer exhibits a flat wavelength dispersion characteristic and the second retardation layer exhibits a positive wavelength dispersion characteristic, the in-plane retardation Re1(550) of the first retardation layer, the in-plane retardation Re2(550) of the second retardation layer, the angle θ 1 formed by the absorption axis of the polarizer and the slow axis of the first retardation layer, and the angle θ 2 formed by the absorption axis of the polarizer and the slow axis of the second retardation layer preferably satisfy the following arbitrary conditions (a) to (D).

(A) Re1(550) is 105 nm-115 nm, Re2(550) is 190 nm-260 nm, theta 1 is 19-35 degrees, and theta 2 is 77-85 degrees.

(B) Re1(550) is 116nm to 125nm, Re2(550) is 200nm to 260nm, theta 1 is 15 to 35 degrees, and theta 2 is 75 to 85 degrees.

(C) Re1(550) is 126-135 nm, Re2(550) is 210-260 nm, theta 1 is 15-35 degrees, and theta 2 is 75-85 degrees.

(D) Re1(550) is 136 nm-145 nm, Re2(550) is 220 nm-270 nm, theta 1 is 15-31 degrees, and theta 2 is 75-83 degrees.

In another embodiment, the first retardation layer exhibits a flat wavelength dispersion characteristic in which the in-plane retardation value hardly changes regardless of the wavelength of the measurement light, and the second retardation layer similarly exhibits a flat wavelength dispersion characteristic in which the in-plane retardation value hardly changes regardless of the wavelength of the measurement light. The in-plane retardation Re1 of the first retardation layer and the in-plane retardation Re2 of the second retardation layer preferably satisfy the following formulas (5) to (8).

Re1(450)/Re1(550)＜1.03 (5)

Re1(650)/Re1(550)＞0.97 (6)

Re2(450)/Re2(550)＜1.03 (7)

Re2(650)/Re2(550)＞0.97 (8)

Typically, one of the first phase difference layer and the second phase difference layer is a refractive index ellipsoid satisfying nx > nz > ny, and the other is a refractive index ellipsoid satisfying nx > ny > nz. That is, one of the first phase difference layer and the second phase difference layer is a negative a plate, and the other is a positive a plate. Typically, the first retardation layer is composed of a stretched polymer film, and the second retardation layer is composed of an oriented cured layer of a liquid crystal compound. The third retardation layer is typically a refractive index ellipsoid satisfying nx > nz > ny. When the optical laminate according to the embodiment of the present invention is applied to an image display device in which a touch sensor layer (first retardation layer), a second retardation layer, a polarizer, and a third retardation layer are arranged in this order from the viewing side, it is possible to suppress a change in hue according to the angle of polarized sunglasses when the polarized sunglasses are worn and a display screen is viewed, and as a result, it is possible to improve the visibility. Note that the description of "ny ═ nz" in the positive a plate or "nx ═ nz" in the negative a plate need not completely coincide with the in-plane refractive index (nx or ny) and the refractive index nz in the thickness direction. For example, a positive a plate with ny ═ Nz can be considered when the Nz coefficient is greater than 0.9 and less than 1.1, and a negative a plate with nx ═ Nz can be considered when the Nz coefficient is greater than-0.1 and less than 0.1.

The optical laminate 100a may practically have a surface protective layer such as a cover glass on the side opposite to the second retardation layer 30 of the touch sensor layer 10, and may have an adhesive layer on the side opposite to the polarizer 40 of the third retardation layer 50. In addition, the optical stack 100a may have a protective layer disposed on one side or both sides of the polarizer 40. Alternatively, the second retardation layer 30 and/or the third retardation layer 50 may also function as a protective layer for the polarizer.

Figure 2 is a schematic cross-sectional view of an optical stack according to another embodiment of the present disclosure. The optical layered body 100b has a structure in which a touch sensor layer 10, a second retardation layer 30, a polarizer 40, a third retardation layer 50, and a fourth retardation layer 60 are sequentially layered. The touch sensor layer 10 and the second phase difference layer 30 are laminated via an adhesive layer 20 having an ultraviolet absorbing function. In the present embodiment, the refractive index ellipsoid of the third retardation layer 50 typically satisfies nx > ny > nz, and the refractive index ellipsoid of the fourth retardation layer 60 typically satisfies nz > nx > ny.

The optical laminate may be sheet-shaped or long.

B. Touch sensor layer

The touch sensor layer can function as a touch sensor for a touch panel. The touch sensor layer includes a first phase difference layer and a transparent conductive layer disposed on one side or both sides of the first phase difference layer.

B-1. first phase difference layer

The first retardation layer preferably exhibits a flat wavelength dispersion characteristic in which the in-plane retardation value hardly changes regardless of the wavelength of measurement light, and has Re1(450)/Re1(550) of less than 1.03 and Re1(650)/Re1(550) of more than 0.97. Re1(450)/Re1(550) is more preferably 0.98 to 1.02, and Re1(650)/Re1(550) is more preferably 0.98 to 1.02.

The thickness of the first retardation layer can be set so as to obtain a desired in-plane retardation. Specifically, the thickness is preferably 1 to 80 μm, more preferably 10 to 60 μm, and most preferably 30 to 50 μm.

The first phase difference layer preferably has a photoelastic coefficient of 2X 10 in absolute value^-11m²A value of not more than N, more preferably 2.0X 10^-13m²/N～1.5×10^-11m²More preferably 1.0X 10^-12m²/N～1.2×10^-11m²A resin of/N. When the absolute value of the photoelastic coefficient is in such a range, the phase difference is less likely to change when the shrinkage stress during heating occurs.

As described above, the first retardation layer is typically a stretched polymer film. The glass transition temperature (Tg) of the resin constituting the polymer film is preferably 50 to 200 ℃, more preferably 60 to 180 ℃, and still more preferably 70 to 160 ℃. When the glass transition temperature of the resin constituting the polymer film is within such a range, deterioration in forming the transparent conductive layer can be prevented.

The polymer film may further contain any suitable additive as required. Specific examples of the additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, solubilizers, crosslinking agents, and tackifiers. The kind and amount of the additive to be used may be appropriately set according to the purpose.

Various surface treatments may be applied to the first retardation layer as necessary. The surface treatment may be carried out by any appropriate method depending on the purpose. Examples thereof include low-pressure plasma treatment, ultraviolet irradiation treatment, corona treatment, inflammation treatment, and acid or alkali treatment. One embodiment is to hydrophilize the surface of the film. When the surface of the film is hydrophilized, the film is excellent in processability when coated with a conductive composition (described later) prepared from an aqueous solvent. In addition, the adhesion between the first retardation layer as a base material and the transparent conductive layer can be improved.

The total light transmittance of the first retardation layer is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more.

In one embodiment, the refractive index ellipsoid of the first retardation layer satisfies a relationship of nx > ny ═ Nz, and the Nz coefficient of the first retardation layer exceeds 0.9 and is less than 1.1, for example. Another embodiment is that the refractive index ellipsoid of the first retardation layer satisfies the relationship of nx ═ Nz > ny, and the Nz coefficient of the first retardation layer is, for example, greater than-0.1 and less than 0.1.

B-1-1. first retardation layer having refractive index ellipsoid satisfying nx > ny ═ nz relationship

The first retardation layer in which the refractive index ellipsoid satisfies the relationship of nx > ny ═ nz may be composed of any suitable material capable of satisfying the optical characteristics and mechanical characteristics as described above. The first retardation layer may be formed of, for example, a resin film containing a cycloolefin resin.

The cycloolefin-based resin is a general term for a resin obtained by polymerizing a cycloolefin as a polymerization unit, and examples thereof include those described in Japanese patent laid-open Nos. 1-240517, 3-14882, and 3-122137. Specific examples thereof include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with α -olefins such as ethylene and propylene (typically random copolymers), graft-modified products obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrogenated products thereof. Specific examples of the cyclic olefin include a norbornene-based monomer. Examples of the norbornene-based monomer include those described in Japanese patent laid-open publication No. 2015-210459 and the like.

In the present invention, other cycloolefins capable of ring-opening polymerization may be used in combination within a range not impairing the object of the present invention. Specific examples of such a cycloolefin include compounds having one reactive double bond such as cyclopentene, cyclooctene, and 5, 6-dihydrodicyclopentadiene.

The cyclic olefin resin preferably has a number average molecular weight (Mn) of 25000 to 200000, more preferably 30000 to 100000, and most preferably 40000 to 80000, as measured by a toluene solvent-based Gel Permeation Chromatography (GPC) method. When the number average molecular weight is in the above range, a resin excellent in mechanical strength and good in solubility, moldability and casting workability can be obtained.

Various cycloolefin resins are commercially available. Specific examples thereof include trade names "ZEONEX" and "ZEONOR" manufactured by japan rui-wen corporation, trade name "Arton" manufactured by JSR corporation, trade name "TOPAS" manufactured by TICONA corporation, and trade name "APEL" manufactured by mitsui chemical co.

The first retardation layer is obtained by, for example, stretching a film made of the above-mentioned cycloolefin-based resin. As a method for forming a film from a cycloolefin resin, any appropriate molding method can be employed. Since the cycloolefin resin is commercially available in a large amount as a film product, the commercially available film may be subjected to a stretching treatment as it is.

The film constituting the first retardation layer may be in the form of a sheet or a long film. In one embodiment, the first retardation layer is produced by cutting the resin film stretched in the longitudinal direction at a predetermined angle with respect to the longitudinal direction. In another embodiment, the first retardation layer is produced by continuously obliquely stretching the long resin film in a direction at a predetermined angle with respect to the long direction. In another embodiment, the first retardation layer is produced by obliquely stretching a laminate of a support base and a resin layer laminated on the support base, and transferring the obliquely stretched resin layer (resin film) to another layer. By employing oblique stretching, a long stretched film having an orientation angle (slow axis in the direction of the angle) of a predetermined angle with respect to the longitudinal direction of the film can be obtained, and for example, when the film is laminated with another layer, roll-to-roll can be realized, and the production process can be simplified. The predetermined angle may be an angle formed by the absorption axis (longitudinal direction) of the polarizer and the slow axis of the first retardation layer.

As the stretching machine for oblique stretching, for example, a tenter type stretching machine capable of applying feeding force or stretching force or drawing force at different speeds in the horizontal and/or longitudinal directions can be cited. The tenter type stretching machine includes a transverse uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, and any suitable stretching machine may be used as long as it can continuously stretch the long resin film obliquely.

By appropriately controlling the left and right speeds in the stretching machine, the first retardation layer having the desired in-plane retardation and the slow axis in the desired direction can be obtained.

The stretching temperature of the film may vary depending on the desired in-plane retardation value and thickness of the first retardation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably from Tg-30 ℃ to Tg +30 ℃, more preferably from Tg-15 ℃ to Tg +15 ℃, and most preferably from Tg-10 ℃ to Tg +10 ℃. By stretching at such a temperature, a first retardation layer having an in-plane retardation that can suitably exhibit the effects of the present invention can be obtained. Further, Tg is the glass transition temperature of the constituent material of the film.

B-1-2. first retardation layer having refractive index ellipsoid satisfying nx ═ nz > ny relationship

The first retardation layer in which the refractive index ellipsoid satisfies the relationship of nx ═ nz > ny may be composed of any suitable material capable of satisfying the optical characteristics and mechanical characteristics as described above. In one embodiment, the first retardation layer may be formed of any appropriate resin film containing a thermoplastic resin having a negative intrinsic birefringence as a main component. A thermoplastic resin having negative intrinsic birefringence means a resin in which, when oriented by stretching or the like, the refractive index in the orientation direction is relatively small. Examples of the thermoplastic resin having negative intrinsic birefringence include resins having a side chain of a polymer introduced with a chemical bond or a functional group having a large polarization anisotropy such as an aromatic group or a carbonyl group, and specific examples thereof include acrylic resins, styrene resins, maleimide resins, and fumarate resins.

The first retardation layer is obtained by, for example, stretching a resin film containing the thermoplastic resin having a negative intrinsic birefringence value as a main component. As the stretching method, any suitable stretching method may be adopted. The method is preferably a method in which a shrinkable film and a resin film containing a thermoplastic resin as a main component are bonded on both sides and are heated and stretched by a longitudinal uniaxial stretching method using a roll stretcher. The shrinkable film is used to impart a shrinking force in a direction perpendicular to the stretching direction during heat stretching and to increase the refractive index (nz) in the thickness direction. The method of bonding the two surfaces of the shrinkable film and the resin film is not particularly limited, and a method of providing and bonding an acrylic adhesive layer containing a (meth) acrylic polymer as a base polymer between the resin film and the shrinkable film is preferable from the viewpoint of excellent workability and economy. The method for forming a resin film constituting a first retardation layer according to the present embodiment is described in detail in jp 2007-193365 a. The contents of the publication are incorporated herein by reference. In one embodiment, the first retardation layer is produced by continuously obliquely stretching the long resin film in a direction at a predetermined angle with respect to the long direction. In this case, the following method is preferable: the resin film to which the shrinkable film is bonded is laminated on a support base, the laminate is obliquely stretched, and the obliquely stretched resin film is transferred to another layer.

B-2 transparent conductive layer

The transparent conductive layer can function as an electrode of a touch sensor. The transparent conductive layer may also be patterned. As the patterning method, any appropriate method may be adopted depending on the form of the transparent conductive layer. The pattern shape of the transparent conductive layer may be any suitable shape according to the application. Examples of the pattern include those described in Japanese patent publication Nos. 2011-511357, 2010-164938, 2008-310550, 2003-511799 and 2010-541109. The transparent conductive layer may be patterned by any appropriate method according to the form of the transparent conductive layer after being formed on the substrate (for example, the first retardation layer).

The surface resistance value of the transparent conductive layer is preferably 0.1. omega./sq to 1000. omega./sq, more preferably 0.5. omega./sq to 500. omega./sq, and particularly preferably 1. omega./sq to 250. omega./sq.

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.

One embodiment is that the transparent conductive layer is formed directly on the first retardation layer. Specific examples of the present embodiment include a method in which a metal oxide layer is formed on the first retardation layer by any suitable film formation method (for example, vacuum deposition, sputtering, CVD, ion plating, spraying, or the like) to obtain a transparent conductive layer. The metal oxide layer may be used as a transparent conductive layer as it is, or may be further heated to crystallize the metal oxide. The temperature during the heating is, for example, 120 to 200 ℃. The transparent conductive layer containing a metal oxide can be patterned by an etching method, a laser method, or the like.

Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferable.

The thickness of the transparent conductive layer is preferably 50nm or less, and more preferably 35nm or less. When the amount is within such a range, a transparent conductive layer having excellent light transmittance can be obtained. The lower limit of the thickness of the transparent conductive layer is preferably 1nm, and more preferably 5 nm.

As another method for directly forming the transparent conductive layer on the first retardation layer, for example, the following methods can be mentioned: coating a composition for forming a transparent conductive layer containing metal nanowires on the first retardation layer; a step of forming a metal mesh by applying a photosensitive composition (composition for forming a transparent conductive layer) containing a silver salt onto the first retardation layer, and then performing exposure treatment and development treatment to form a metal thin wire into a predetermined pattern; a composition for forming a transparent conductive layer containing a conductive polymer is applied on the first retardation layer.

C. Second phase difference layer

In one embodiment, the second phase difference layer exhibits positive wavelength dispersion characteristics in which the in-plane retardation value is smaller as the wavelength of the measurement light is larger, and Re2(450)/Re2(550) is 1.03 or more, and Re2(650)/Re2(550) is 0.97 or less. Re2(450)/Re2(550) is more preferably 1.03 to 1.15, and Re2(650)/Re2(550) is more preferably 0.90 to 0.97. In another embodiment, the second phase difference layer exhibits a flat wavelength dispersion characteristic in which the in-plane phase difference value hardly changes regardless of the wavelength of measurement light, and Re2(450)/Re2(550) is less than 1.03, and Re2(650)/Re2(550) is greater than 0.97. Re2(450)/Re2(550) is more preferably 0.98 to 1.02, and Re2(650)/Re2(550) is more preferably 0.98 to 1.02.

C-1. second retardation layer exhibiting positive wavelength dispersion characteristics

When the first retardation layer exhibits a flat wavelength dispersion characteristic and the second retardation layer exhibits a positive wavelength dispersion characteristic, Re1(550), Re2(550), θ 1, and θ 2 preferably satisfy any one of the following (a) to (D) as described above.

When the first retardation layer exhibits flat wavelength dispersion characteristics and the second retardation layer exhibits positive wavelength dispersion characteristics, Re1(550), Re2(550), θ 1, and θ 2 are more preferably any of the following (E) to (G).

(E) Re1(550) is 105 nm-115 nm, Re2(550) is 210 nm-250 nm, theta 1 is 19-35 degrees, and theta 2 is 77-85 degrees.

(F) Re1(550) is 116nm to 135nm, Re2(550) is 220nm to 260nm, theta 1 is 19 to 31 degrees, and theta 2 is 77 to 83 degrees.

(G) Re1(550) is 136 nm-145 nm, Re2(550) is 220 nm-260 nm, theta 1 is 19-27 degrees, and theta 2 is 77-81 degrees.

When the first retardation layer exhibits a flat wavelength dispersion characteristic and the second retardation layer exhibits a positive wavelength dispersion characteristic, Re1(550), Re2(550), θ 1, and θ 2 most preferably satisfy any of the following (H) to (K).

(H) Re1(550) is 105nm to 115nm, Re2(550) is 220nm to 230nm, theta 1 is 23 to 27 degrees, and theta 2 is 79 to 81 degrees.

(I) Re1(550) is 116nm to 125nm, Re2(550) is 220nm to 250nm, theta 1 is 19 to 27 degrees, and theta 2 is 77 to 81 degrees.

(J) Re1(550) is 126-135 nm, Re2(550) is 230-250 nm, theta 1 is 19-27 DEG, and theta 2 is 77-81 deg.

(K) Re1(550) is 136 nm-145 nm, Re2(550) is 245 nm-255 nm, theta 1 is 19-23 degrees, and theta 2 is 77-79 degrees.

The thickness of the second retardation layer may be set so as to obtain a desired in-plane retardation. Specifically, the thickness is preferably 1 μm to 80 μm. When the second retardation layer is composed of an alignment cured layer of a liquid crystal compound, the thickness is more preferably 1 μm to 10 μm, and still more preferably 1 μm to 6 μm.

In one embodiment, the refractive index ellipsoid of the second retardation layer satisfies a relationship of nx ═ Nz > ny, and the Nz coefficient of the second retardation layer is, for example, greater than-0.1 and less than 0.1. Another embodiment is that the refractive index ellipsoid of the second retardation layer satisfies a relationship of nx > ny ═ Nz, and the Nz coefficient of the second retardation layer is, for example, more than 0.9 and less than 1.1.

C-1-1. second retardation layer in which an ellipsoid of refractive index satisfies the relationship nx > ny ═ nz

The second retardation layer in which the refractive index ellipsoid satisfies the relationship of nx > ny ═ nz may be composed of any suitable material capable of satisfying the optical characteristics and mechanical characteristics as described above. One embodiment is that the second retardation layer may be composed of an alignment cured layer of a liquid crystal compound. By using the liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be made remarkably larger than that of a non-liquid crystal material, and therefore the thickness of the retardation layer for obtaining a desired in-plane retardation can be remarkably reduced. As a result, the optical laminate (eventually, the image display device) can be further thinned. The "alignment cured layer" refers to a layer in which a liquid crystal compound is aligned in a prescribed direction within the layer and the alignment state thereof is fixed in this specification. In this embodiment, the rod-like liquid crystal compound is typically aligned in the slow axis direction of the second phase difference layer (horizontal alignment). Examples of the liquid crystal compound include a liquid crystal compound in which a liquid crystal phase is a nematic phase (nematic liquid crystal). As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The mechanism of expression of liquid crystallinity of the liquid crystal compound may be either of a lyotropic type or a thermotropic type. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. The reason for this is that: by polymerizing or crosslinking the liquid crystal monomer, the alignment state of the liquid crystal monomer can be fixed. After the liquid crystal monomers are aligned, for example, in the case of polymerizing or crosslinking the liquid crystal monomers with each other, the above-described alignment state can be fixed thereby. Here, the polymer is formed by polymerization, and a three-dimensional network structure is formed by crosslinking, and these are non-liquid crystalline. Therefore, the formed second retardation layer does not undergo transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change, which is typical of a liquid crystalline compound, for example. As a result, the second retardation layer becomes a retardation layer having extremely excellent stability against temperature change.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the kind thereof. Specifically, the temperature range is preferably 40 to 120 ℃, more preferably 50 to 100 ℃, and most preferably 60 to 90 ℃.

As the liquid crystal monomer, any suitable liquid crystal monomer can be used. For example, polymerizable mesogenic compounds described in Japanese patent application laid-open No. 2002-533742(WO00/37585), EP358208(US5211877), EP66137(US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, GB2280445 and the like can be used. Specific examples of such polymerizable mesogenic compounds include trade name LC242 manufactured by BASF corporation, trade name E7 manufactured by Merck corporation, and trade name LC-Sillicon-CC3767 manufactured by Wacker-Chem corporation. The liquid crystal monomer is preferably a nematic liquid crystal monomer, for example.

The alignment cured layer of the liquid crystal compound may be formed by: the method for producing a liquid crystal display device includes applying an alignment treatment to a surface of a predetermined substrate, applying a coating liquid containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the aligned state. In one embodiment, the substrate is any suitable resin film and the oriented cured layer formed on the substrate can be transferred to the surface of the touch sensor layer.

As the alignment treatment, any appropriate alignment treatment may be adopted. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment may be mentioned. Specific examples of the mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of the physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of the chemical alignment treatment include oblique vapor deposition and photo alignment treatment. The treatment conditions for the various alignment treatments may be any suitable conditions according to the purpose.

The alignment of the liquid crystal compound is performed by performing a treatment at a temperature at which a liquid crystal phase is exhibited according to the kind of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound is brought into a liquid crystal state, and the liquid crystal compound is aligned in accordance with the alignment treatment direction of the substrate surface.

In one embodiment, the fixing of the alignment state is performed by cooling the liquid crystal compound after alignment as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound after alignment as described above to polymerization treatment or crosslinking treatment.

Specific examples of the liquid crystal compound and the method for forming the alignment cured layer are described in japanese patent application laid-open No. 2006-163343. The contents of the publication are incorporated herein by reference.

C-1-2. a second retardation layer in which an ellipsoid of refractive index satisfies the relationship of nx ═ nz > ny

The second retardation layer in which the refractive index ellipsoid satisfies the relationship of nx ═ nz > ny may be composed of any suitable material capable of satisfying the optical characteristics and mechanical characteristics as described above.

In one embodiment, the second retardation layer may be composed of an alignment cured layer of a liquid crystalline composition containing a discotic liquid crystalline compound which is substantially vertically aligned. The term "discotic liquid crystal compound" as used herein means a compound having a molecular structure comprising discotic mesogens and 2 to 8 side chains radially bonded to the mesogens via ether bonds or ester bonds. Examples of mesogens include those having a structure shown in fig. 1 on page 22 of a liquid crystal dictionary (published by peifensian). Specifically, benzene, triphenylene, truxene (truxene), pyran, hexacarboxylanthracene (rufigollol), porphyrin, metal complex, and the like. Ideally, the discotic liquid crystal compound which is substantially vertically aligned has an optical axis in one direction in the film plane. The term "substantially homeotropically aligned discotic liquid crystal compound" refers to a liquid crystal compound in which the disc surface of the discotic liquid crystal compound is perpendicular to the film plane and the optical axis is parallel to the film plane.

The liquid crystalline composition containing a discotic liquid crystalline compound is not particularly limited as long as it contains a discotic liquid crystalline compound and exhibits liquid crystallinity. The content of the discotic liquid crystal compound in the liquid crystalline composition is preferably 40 parts by weight or more and less than 100 parts by weight, more preferably 50 parts by weight or more and less than 100 parts by weight, and most preferably 70 parts by weight or more and less than 100 parts by weight, based on 100 parts by weight of the total solid content of the liquid crystalline composition.

The retardation film formed from the alignment cured layer of the liquid crystalline composition containing the discotic liquid crystalline compound in a substantially homeotropic alignment can be obtained, for example, by the method described in Japanese patent laid-open No. 2001-56411. The discotic liquid crystal compound in the liquid crystal composition may be oriented along a regulating force imparted by an alignment treatment such as a rubbing treatment or a photo-alignment treatment. Therefore, by performing the alignment treatment so that the restraining force acts in a desired direction and applying the liquid crystal composition thereon, a rolled retardation film (negative a plate) having a slow axis in a desired direction can be produced without performing the stretching and shrinking treatment thereafter. The rolled retardation film having a slow axis in a desired direction can be rolled up when laminated with a polarizer or a touch sensor layer.

In another embodiment, the second retardation layer may be composed of an alignment cured layer of a liquid crystalline composition containing a horizontally aligned lyotropic liquid crystal compound. The term "lyotropic liquid crystal compound" as used herein means a liquid crystal compound which exhibits a liquid crystal phase in a solution state depending on the concentration of a solute. As the above lyotropic liquid crystal compound, any suitable lyotropic liquid crystal compound can be used. Specific examples of the lyotropic liquid crystal compound include an amphiphilic compound having a hydrophilic group and a hydrophobic group at both ends of a molecule, a water-soluble coloring compound having an aromatic ring, and a polymer compound having a rod-like skeleton in the main chain, such as a cellulose derivative, a polypeptide, and a nucleic acid. Among them, the retardation film used for the second phase difference layer is preferably an oriented cured layer of a liquid crystalline composition containing a horizontally oriented lyotropic liquid crystal compound which is a chromophoric compound having an aromatic ring and imparted with water solubility.

The liquid crystalline composition containing a lyotropic liquid crystal compound is not particularly limited as long as it contains a lyotropic liquid crystal compound and exhibits liquid crystallinity. The content of the discotic liquid crystal compound in the liquid crystalline composition is preferably 40 parts by weight or more and less than 100 parts by weight, more preferably 50 parts by weight or more and less than 100 parts by weight, and most preferably 70 parts by weight or more and less than 100 parts by weight, based on 100 parts by weight of the total solid content of the liquid crystalline composition.

The retardation film formed from the alignment cured layer of the liquid crystalline composition containing the horizontally aligned lyotropic liquid crystal compound can be obtained, for example, by the method described in Japanese patent laid-open publication No. 2002-296415. The lyotropic liquid crystal compound in the liquid crystal composition may be oriented along the confining force imparted by the alignment treatment such as rubbing treatment or photo-alignment treatment. Therefore, by performing the alignment treatment so that the restraining force acts in a desired direction and applying the liquid crystal composition thereon, a retardation film having a slow axis in a desired direction can be produced without performing the stretching and shrinking treatment thereafter. The rolled retardation film having a slow axis in a desired direction can be rolled up when laminated with a polarizer or a touch sensor layer.

C-2. second retardation layer exhibiting flat wavelength dispersion characteristics

As described above, the second phase difference layer may be a phase difference layer exhibiting a flat wavelength dispersion characteristic in which the in-plane phase difference value is almost constant regardless of the wavelength of the measurement light.

The thickness of the second retardation layer may be set so as to obtain a desired in-plane retardation. Specifically, the thickness is preferably 1 to 160 μm, more preferably 10 to 80 μm, and most preferably 20 to 50 μm.

In one embodiment, the refractive index ellipsoid of the second retardation layer satisfies a relationship of nx > ny ═ Nz, and the Nz coefficient of the second retardation layer exceeds 0.9 and is less than 1.1, for example. Another embodiment is that the refractive index ellipsoid of the second phase difference layer satisfies a relationship of nx ═ Nz > ny, and the Nz coefficient of the second phase difference layer is, for example, larger than-0.1 and smaller than 0.1.

The second retardation layer in which the refractive index ellipsoid satisfies the relationship of nx > ny ═ nz may be composed of any suitable material capable of satisfying the optical characteristics and mechanical characteristics as described above. Examples of the material include those described in the above item B-1-1. The second retardation layer having the refractive index ellipsoid satisfying the relationship of nx ═ nz > ny may be formed of any suitable material capable of satisfying the optical characteristics and mechanical characteristics described above. Examples of the material include those described in the above-mentioned item B-1-2.

D. Polarizer

As the polarizer, any suitable polarizer can be used. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of the polarizer made of a single-layer resin film include a film obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film to a dyeing treatment with a dichroic material such as iodine or a dichroic dye and a stretching treatment; and polyene-based oriented films such as dehydrated products of PVA and desalted products of polyvinyl chloride. From the viewpoint of excellent optical properties, it is preferable to use a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the PVA film.

The dyeing with iodine can be performed by, for example, immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment, or may be performed while dyeing. In addition, dyeing may be performed after stretching. The PVA based film may be subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, and the like as required. For example, the PVA film may be immersed in water and washed with water before dyeing, whereby stains and antiblocking agents on the surface of the PVA film can be washed off, and the PVA film can be swollen to prevent uneven dyeing.

Specific examples of the polarizer obtained using the laminate include polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate by coating. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate by coating can be produced, for example, by: coating a PVA-based resin solution on a resin base material, and drying the coating to form a PVA-based resin layer on the resin base material, thereby obtaining a laminate of the resin base material and the PVA-based resin layer; the laminate is stretched and dyed to form a polarizer from the PVA-based resin layer. In the present embodiment, the stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Further, the stretching may further comprise subjecting the laminate to in-air stretching at a high temperature (e.g., 95 ℃ or higher) before stretching in the aqueous boric acid solution, if necessary. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer for a polarizer), or the resin substrate may be peeled from the resin substrate/polarizer laminate and an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface. The details of the method for producing such a polarizer are described in, for example, japanese patent laid-open No. 2012 and 73580. The entire contents of the publication are incorporated herein by reference.

The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, and still more preferably 3 μm to 8 μm. When the thickness of the polarizer is in such a range, the warpage during heating can be favorably suppressed, and favorable durability of appearance during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380nm to 780 nm. The single transmission (single transmission) of the polarizer is preferably 42.0% to 46.0%, more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

E. Third phase difference layer

The thickness of the third retardation layer is preferably 0.1 to 50 μm, more preferably 10 to 30 μm. The third retardation layer preferably doubles as a protective layer for the polarizer. In this case, no other protective layer may be provided between the polarizer and the third retardation layer. In this case, the third retardation layer is laminated with the polarizer through an arbitrary appropriate adhesive layer.

In one embodiment, the refractive index ellipsoid of the third phase difference layer satisfies nx > Nz > ny, and the Nz coefficient of the third phase difference layer is, for example, 0.1 to 0.9.

Another embodiment is that the refractive index ellipsoid of the third phase difference layer satisfies the relationship nx > ny > nz. The Nz coefficient of the third phase difference layer is, for example, 1.1 or more and, for example, 20 or less. In this case, the optical laminate has a fourth phase difference layer having a refractive index ellipsoid satisfying a relationship nz > nx > ny.

E-1. third retardation layer having refractive index ellipsoid satisfying nx > nz > ny relationship

The in-plane retardation Re3(550) of the third retardation layer in which the refractive index ellipsoids satisfy the relationship of nx > nz > ny is 150 to 400nm, more preferably 180 to 350 nm. The angle theta 3 formed by the absorption axis of the polarizer and the slow axis of the third phase difference layer is preferably 87-93 degrees or-3 degrees, and more preferably 89-91 degrees or-1 degrees.

The third phase difference layer may be composed of any suitable material that satisfies the optical and mechanical properties described above. One embodiment may be formed of any appropriate retardation film. Preferably, the retardation film contains at least one thermoplastic resin selected from the group consisting of norbornene resins, cellulose resins, carbonate resins, and ester resins. The retardation film more preferably contains at least one thermoplastic resin selected from norbornene resins and carbonate resins. This is because the composition is excellent in heat resistance, transparency and moldability. As a method for producing the retardation film, any appropriate method can be used. Typically, for example, the following methods are listed: a thermoplastic resin or a composition containing the thermoplastic resin is formed into a sheet to prepare a polymer film, and a shrinkable film is laminated to one surface or both surfaces of the polymer film and then heated and stretched. Examples of the heat stretching include heat stretching by a longitudinal uniaxial stretching method using a roll stretcher.

E-2. third retardation layer having refractive index ellipsoid satisfying nx > ny > nz relationship

The in-plane retardation Re3(550) of the third retardation layer in which the refractive index ellipsoids satisfy the relationship of nx > ny > nz is 90 to 160nm, and more preferably 110 to 155 nm. The angle θ 3 formed by the absorption axis of the polarizer and the slow axis of the third retardation layer is preferably 87 ° to 93 °, more preferably 89 ° to 91 °. The third phase difference layer may be made of any suitable material that can satisfy the optical and mechanical properties described above.

In one embodiment, the third retardation layer may be formed of any appropriate retardation film. The resin forming the retardation film is preferably a norbornene resin or a polycarbonate resin. As the method for producing the retardation film, any suitable method including a stretching step of the resin film may be employed. Examples of the stretching method include transverse uniaxial stretching (fixed-end biaxial stretching) and sequential biaxial stretching. The stretching temperature is preferably 135-165 ℃, and more preferably 140-160 ℃. The stretch ratio is preferably 2.8 to 3.2 times, and more preferably 2.9 to 3.1 times.

In another embodiment, the third retardation layer may be made of any suitable non-liquid crystal material. In this case, the thickness of the third retardation layer is typically 0.1 to 10 μm, more preferably 0.1 to 8 μm, and particularly preferably 0.1 to 5 μm. The non-liquid crystal material is preferably a non-liquid crystal polymer; specifically, polymers such as polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide are preferable. These polymers may be used alone or as a mixture of two or more thereof. The third retardation layer can be formed typically by applying a solution of the above-mentioned non-liquid crystal polymer to a base film and removing the solvent. In the method for forming the third retardation layer, it is preferable to perform a treatment (for example, a stretching treatment) for imparting optical biaxiality (nx > ny > nz). By performing such processing, a difference in refractive index (nx > ny) can be reliably imparted in-plane. Further, as a specific example of the polyimide and a specific example of a method for forming the third retardation layer, the polymer and the production method described in Japanese patent laid-open No. 2006-234848 can be mentioned.

F. A fourth phase difference layer

The fourth retardation layer shows a refractive index characteristic showing a relationship of nz > nx > ny as described above. The in-plane retardation Re4(550) of the fourth retardation layer is preferably 10nm to 150nm, more preferably 10nm to 80 nm. The Nz coefficient of the fourth phase difference layer is, for example, -0.1 or less, preferably-2.0 or less. The angle formed by the absorption axis of the polarizer and the slow axis of the fourth phase difference layer is preferably 87-93 degrees, more preferably 89-91 degrees

The fourth phase difference layer may be made of any suitable material that can satisfy the optical and mechanical properties described above. One embodiment is that the fourth phase difference layer may be composed of a liquid crystal layer fixed in a vertical orientation. The liquid crystal material (liquid crystal compound) capable of vertical alignment may be either 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 the methods for forming the liquid crystal compounds described in [0020] to [0042] of Japanese patent laid-open publication No. 2002-333642. In this case, the thickness is preferably 0.1 to 6 μm, more preferably 0.2 to 3 μm. In another embodiment, the fourth retardation layer may be a retardation film formed of a fumaric diester resin as described in Japanese patent laid-open No. 2012-32784. In this case, the thickness is preferably 5 to 50 μm, more preferably 5 to 35 μm.

G. Adhesive layer

The adhesive layer is typically an adhesive layer or an adhesive layer. The adhesive layer is preferably a transparent adhesive layer, and the transmittance (23 ℃) at a wavelength of 590nm may be, for example, 80% or more, preferably 85% or more, and more preferably 90% or more. The adhesive layer may have an ultraviolet absorbing function. In this case, it is preferable that the adhesive layer has an ultraviolet absorbing function from the viewpoint of ensuring a sufficient thickness and consequently exhibiting a good ultraviolet absorbing effect. For example, an adhesive layer disposed between the touch sensor layer and the second phase difference layer has an ultraviolet absorption function. The average light transmittance of the adhesive layer having an ultraviolet absorbing function at a wavelength of 300nm to 400nm is preferably 5% or less, more preferably 4% or less, and still more preferably 3% or less. The average light transmittance of the adhesive layer at a wavelength of 450 to 500nm is preferably 70% or more, more preferably 75% or more, and still more preferably 80% or more. The average light transmittance of the adhesive layer at a wavelength of 500nm to 780nm is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more.

As the adhesive composition constituting the adhesive layer, any appropriate adhesive composition can be used. Examples thereof include aqueous adhesive compositions such as isocyanate-based, polyvinyl alcohol-based, gelatin-based, vinyl emulsion-based, aqueous polyurethane and aqueous polyester, and curable adhesive compositions such as ultraviolet-curable adhesives and electron beam-curable adhesives. The thickness of the adhesive layer may be, for example, 0.1 to 5 μm.

As the adhesive composition for forming the adhesive layer, any suitable adhesive composition can be used. For example, there may be mentioned rubber-based, acrylic-based, silicone-based, urethane-based, vinyl alkyl ether-based, polyvinyl alcohol-based, polyvinyl pyrrolidone-based, polyacrylamide-based, cellulose-based adhesive compositions. Among them, acrylic pressure-sensitive adhesive compositions are preferably used from the viewpoint of excellent optical transparency and excellent pressure-sensitive adhesive properties, weather resistance, heat resistance and the like.

The acrylic pressure-sensitive adhesive composition contains a partial polymer of a monomer component containing an alkyl (meth) acrylate and/or a (meth) acrylic polymer obtained from the monomer component as a base polymer.

Examples of the alkyl (meth) acrylate include alkyl (meth) acrylates having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester end. The alkyl (meth) acrylate may be used singly or in combination of two or more. In addition, "(meth) acrylate" means acrylate and/or methacrylate in the present specification.

Examples of the alkyl (meth) acrylate include branched alkyl (meth) acrylates having 4 to 9 carbon atoms. The alkyl (meth) acrylate is preferable from the viewpoint of easily obtaining a balance of adhesive properties. Specific examples thereof include n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, and isononyl (meth) acrylate, and these can be used singly or in combination of two or more.

In the present invention, the alkyl (meth) acrylate having an alkyl group having 1 to 24 carbon atoms at the ester end is preferably 40% by weight or more, more preferably 50% by weight or more, and still more preferably 60% by weight or more, based on the total amount of monofunctional monomer components forming the (meth) acrylic polymer.

The monomer component may contain a comonomer other than the alkyl (meth) acrylate as a monofunctional monomer component. The comonomer may be used as the remainder of the above-mentioned alkyl (meth) acrylate in the monomer component.

As the above-mentioned comonomer and the amount thereof to be used, those described in Japanese patent laid-open publication No. 2016-157077, paragraphs 0029 to 0042, and the amount thereof to be used can be applied.

The monomer component forming the (meth) acrylic polymer may contain a polyfunctional monomer, if necessary, in addition to the monofunctional monomer, in order to adjust the cohesive force of the adhesive.

The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and examples thereof include: ester compounds of a polyhydric alcohol and (meth) acrylic acid such as (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 2-ethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 12-dodecanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and tetramethylolmethane tri (meth) acrylate; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di (meth) acrylate, and the like. Among them, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate can be preferably used. The polyfunctional monomer may be used alone or in combination of two or more.

The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, and the like, but is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and still more preferably 1 part by weight or less, based on 100 parts by weight of the total amount of the monofunctional monomers. The lower limit is not particularly limited, but is preferably 0 part by weight or more, and more preferably 0.001 part by weight or more. When the amount of the polyfunctional monomer used is within the above range, the adhesive strength can be improved.

The (meth) acrylic polymer can be produced by any suitable method. For example, radical polymerization methods such as solution polymerization, radiation polymerization such as Ultraviolet (UV) polymerization, bulk polymerization, and emulsion polymerization can be appropriately selected. The obtained (meth) acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

When the (meth) acrylic polymer is produced by radical polymerization, a polymerization initiator, a chain transfer agent, an emulsifier, and the like, which are generally used in radical polymerization, may be added to the monomer component as needed to carry out polymerization. As the radical polymerization initiator, for example, various known initiators such as azo type and peroxide type initiators can be used. The reaction temperature can be usually set to about 50 to 80 ℃ and the reaction time can be set to 1 to 8 hours. For example, in the case of the solution polymerization method, ethyl acetate, toluene, or the like is generally used as a solvent for the (meth) acrylic polymer. The concentration of the solution is usually set to about 20 to 80 wt%. The weight average molecular weight of the (meth) acrylic polymer can be controlled by the kind, amount used, reaction conditions, and the like of the polymerization initiator and the chain transfer agent.

Specific examples of photopolymerization initiators and the amounts and reaction conditions used in the production of the above (meth) acrylic polymers by radiation polymerization can be found in Japanese patent laid-open Nos. 2016-157077, 0054-0070.

Examples of the ultraviolet absorber that can be contained in the adhesive composition include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and the like. These may be used alone or in combination of two or more. Among them, preferred are triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers, and more preferred is at least one ultraviolet absorber selected from triazine-based ultraviolet absorbers having two or less hydroxyl groups in one molecule and benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton in one molecule. These ultraviolet absorbers have good solubility in monomer components and high ultraviolet absorbability at a wavelength of about 380 nm.

Specific examples of the ultraviolet absorber and the amount thereof to be used are described in Japanese patent laid-open Nos. 2016-157077, 0048-0053.

The adhesive composition may contain a crosslinking agent. Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl ether melamine crosslinking agents, metal chelate crosslinking agents, and peroxides. The crosslinking agent may be used singly or in combination of two or more. Among them, an isocyanate-based crosslinking agent is preferably used.

The blending ratio of the (meth) acrylic polymer and the crosslinking agent is usually preferably about 0.001 to 20 parts by weight, more preferably about 0.01 to 15 parts by weight, of the crosslinking agent (solid content) per 100 parts by weight of the (meth) acrylic polymer (solid content).

The adhesive composition may further contain, as required: tackifiers such as rosin derivative resins, polyterpene resins, petroleum resins, and oil-soluble phenol resins; a plasticizer; fillers such as hollow glass microspheres (hollow glass balloon); a pigment; a colorant; an antioxidant; an anti-aging agent; silane coupling agents, and the like. The amount of the additive to be used may be appropriately set according to the purpose. For example, the amount of the silane coupling agent used is preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, and still more preferably 0.02 to 0.6 part by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer.

The adhesive composition is preferably adjusted to a viscosity suitable for coating work. The viscosity can be adjusted by adding a tackifying polymer, a polyfunctional monomer, or the like, or by partially polymerizing a monomer component in the adhesive composition. The partial polymerization may be performed before or after the addition of the thickening polymer, the polyfunctional monomer, or the like. The viscosity of the pressure-sensitive adhesive composition varies depending on the composition of the monomer component, the kind and amount of the additive, and the like, and therefore, it is difficult to uniquely determine the preferable polymerization rate of the partial polymerization, but the polymerization rate may be, for example, about 20% or less, preferably about 3% to 20%, and more preferably about 5% to 15%. When the polymerization rate in the partial polymerization exceeds 20%, the viscosity becomes too high and the application to the substrate becomes difficult.

The adhesive layer is formed by applying the adhesive composition to various substrates, and drying, irradiation with radiation, or the like as necessary. When the adhesive layer is formed on a release film, the adhesive layer can be used by transferring it from the release film to a desired member.

The thickness of the adhesive layer can be appropriately set according to the purpose. The thickness of the adhesive layer containing no ultraviolet absorber is, for example, 1 to 100. mu.m, preferably 3 to 50 μm, and more preferably 5 to 30 μm. On the other hand, from the viewpoint of suitably exhibiting the ultraviolet absorbing function, the thickness of the adhesive layer containing an ultraviolet absorber (for example, the adhesive layer disposed between the touch sensor layer and the second phase difference layer) may be, for example, 50 μm or more, preferably 100 μm or more, and more preferably 150 μm or more. The thickness may be, for example, 10mm or less.

H. Manufacturing method

The method for producing an optical laminate of the present invention typically includes the steps of: the first long film constituting the touch sensor layer, the second long film constituting the second phase difference layer, the polarizer long film, and the third long film constituting the third phase difference layer are continuously bonded to the adjacent films while being conveyed. The bonding surface of the touch sensor layer is not limited, and the touch sensor layer is preferably bonded so that the transparent conductive layer and the second film face each other.

In one embodiment, the method for producing the optical laminate includes a step of bonding the second film formed on the substrate to the first film via an adhesive layer having an ultraviolet absorbing function, and then peeling the substrate. In another embodiment, the polarizer is formed on a substrate, and the method for producing an optical laminate includes a step of peeling the substrate after the polarizer formed on the substrate is bonded to the second film. In still another embodiment, the third thin film is formed on a substrate, and the method for producing an optical laminate includes a step of peeling the substrate after the third thin film formed on the substrate is attached to the polarizer. Two or more of the above embodiments may be combined.

I. Image display device

The optical laminate is suitably used for an image display device such as a liquid crystal display device. Accordingly, the present invention includes an image display device using the optical laminate. The image display device according to the embodiment of the present invention includes the optical laminate described above such that the touch sensor layer (first retardation layer), the second retardation layer, the polarizer, and the third retardation layer are arranged in this order from the viewing side of the image display device.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement method of each characteristic is as follows.

(1) Thickness of

The measurement was carried out using a digital micrometer (KC-351C, manufactured by Anli corporation).

(2) Phase difference value

The refractive indices nx, ny, and nz of the retardation layers used in the examples and comparative examples were measured by an automatic birefringence measurement apparatus (manufactured by prince measurement machine, KOBRA-WPR). The in-plane retardation Re was measured at wavelengths of 450nm, 550nm and 650nm, the thickness direction retardation Rth was measured at a wavelength of 550nm and a measurement temperature of 23 ℃.

(3) Hue change and transmittance change according to angle of polarized sunglasses

A light source (product name "JCR 12V 50W 20H" manufactured by yazaki electric corporation) was disposed on the back surface side (third retardation layer side) of the optical laminate, and a polarizer simulating polarized sunglasses was disposed on the front surface side (touch sensor layer side) of the optical laminate. The light emitted from the light source and transmitted through the optical laminate and the polarizer was measured spectrally by using an integrating sphere type partial light transmittance measuring instrument DOT-3C (manufactured by color technology research, mura, ltd.) while rotating the polarizer in a range of 90 ° to-90 °. The hues a and b of the Hunter Lab color system were calculated from the obtained spectrum of the transmitted light, and plotted on coordinates with the horizontal axis being a and the vertical axis being b. The horizontal axis is set to the angle of the polarizer simulating the polarized sunglasses, and the vertical axis is set to the transmittance (Y value) to be plotted.

< example 1 >

1. Production of touch sensor sheet A having first retardation layer and transparent conductive layer disposed on one side thereof

A cycloolefin resin film (trade name "ZEONOR ZF 14" manufactured by Nippon Ralskikai Co., Ltd., thickness: 55 μm) obtained by hydrogenating a ring-opened polymer of a norbornene monomer in a long form was stretched at a stretching temperature of 145 ℃ in the longitudinal direction at a stretching ratio of 1.5 times, to obtain a stretched film having a thickness of 45 μm. Then, the film was stretched at a stretching ratio of 2.0 times and a stretching temperature of 142 ℃ in an oblique direction to prepare a retardation film. The retardation film had a thickness of 23 μm, an in-plane retardation Re (550) of 110nm, an Re (450)/Re (550) of 1.00, an Re (650)/Re (550) of 1.00, a refractive index ellipsoid satisfying a relationship of nx > ny ≈ Nz (0.9 < Nz coefficient < 1.1), and an angle formed by a slow axis and a longitudinal direction of 25 °.

The surface of the obtained retardation film was hydrophilized by performing corona treatment on one surface thereof. Then, a metal mesh (grid having a line width of 100 μm and a pitch of 1.5 mm) was formed on the corona-treated surface by screen printing using a silver paste (product name "RA FS 039" manufactured by tokyo corporation) and fired at 120 ℃ for 10 minutes to form a transparent conductive layer. Thus, a touch sensor sheet a in which a transparent conductive layer was directly formed on one surface of the retardation film was obtained.

2. Preparation of cured layer B of liquid Crystal Compound constituting second phase Difference layer

A photo-alignment film was applied to the surface of a long polyethylene terephthalate base material (PET base material) having a thickness of 100 μm, and photo-alignment treatment was performed in a direction of 10 ° with respect to the long direction. On the other hand, 10 parts by weight of a polymerizable discotic liquid crystal compound described in section 0111 of Japanese patent No. 5186150 and 3 parts by weight of a photopolymerization initiator (product name IRGACURE 907 manufactured by BASF) for the polymerizable liquid crystal monomer were dissolved in 40 parts by weight of toluene to prepare a liquid crystal coating liquid. The surface of the PET substrate subjected to the photo-alignment treatment was coated with the coating liquid by a bar coater, and then heated and dried at 80 ℃ for 4 minutes to align the liquid crystal. The liquid crystal layer was irradiated with ultraviolet rays to cure the liquid crystal layer, thereby obtaining an elongated laminate (alignment cured layer laminate) in which an alignment cured layer B was formed on a PET substrate. The thickness of the orientation cured layer B was 2 μm, the in-plane retardation Re (550) was 220nm, Re (450)/Re (550) was 1.08, Re (650)/Re (550) was 0.96, the refractive index ellipsoid satisfied the relationship of nx ═ nz > ny, and the angle formed by the slow axis and the longitudinal direction was 80 °.

3. Production of polarizer

A long amorphous polyethylene terephthalate (A-PET) film (trade name "NOVACLEAR", manufactured by Mitsubishi resin Co., Ltd., thickness: 100 μm) was prepared as a base material, and an aqueous solution of a polyvinyl alcohol (PVA) resin (trade name "GOHSENOL (registered trade name) NH-26", manufactured by Nippon synthetic chemical Co., Ltd.) was applied to one surface of the base material at 60 ℃ and dried to form a PVA-based resin layer having a thickness of 7 μm. The laminate thus obtained was immersed in an insolubilizing bath having a liquid temperature of 30 ℃ for 30 seconds (insolubilizing step). Subsequently, the substrate was immersed in a dyeing bath at a liquid temperature of 30 ℃ for 60 seconds (dyeing step). Subsequently, the resultant was immersed in a crosslinking bath having a liquid temperature of 30 ℃ for 30 seconds (crosslinking step). Then, the laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds while being immersed in an aqueous boric acid solution having a liquid temperature of 60 ℃. The dipping time in the aqueous boric acid solution was 120 seconds, and the laminate was stretched just before the fracture. Thereafter, the laminate was immersed in a cleaning bath and then dried with warm air at 60 ℃ (cleaning and drying step). Thus, a long-shaped laminate (polarizer laminate) in which a polarizer having a thickness of 5 μm was formed on a base material was obtained.

4. Production of retardation film C constituting third retardation layer

A long norbornene-based resin-containing polymer film (trade name "ZEONOR ZF-14-100", manufactured by Optes) having a thickness of 100 μm was bonded on one side to a shrinkable film (trade name "TORAYFAN BO 2873", manufactured by Toray corporation) having a thickness of 60 μm via an acrylic adhesive layer (thickness 15 μm), the resulting film was stretched in an air circulating oven at 146 ℃ by a factor of 1.38 to obtain a long laminate (retardation film laminate) in which a long retardation film C was formed on a shrinkable film, the retardation film C had a thickness of 17 μm, an in-plane retardation Re (550) of 275nm, an Re (450)/Re (550) of 1.10, an Re (650)/Re (550) of 0.95, and refractive index ellipsoids satisfied the relationship of nx > nz > ny, and the angle formed by the slow axis and the long direction was 90 °.

5. Preparation of adhesive layer having ultraviolet absorption function

A monomer mixture comprising 76 parts by weight of 2-ethylhexyl acrylate (2EHA), 16 parts by weight of N-vinyl-2-pyrrolidone (NVP) and 8 parts by weight of 2-hydroxyethyl acrylate (HEA) was mixed with 0.035 parts by weight of 1-hydroxycyclohexyl phenyl ketone (trade name: IRGACURE 184, manufactured by BASF corporation, having an absorption band at a wavelength of 200 to 370 nm) and 0.035 parts by weight of 2, 2-dimethoxy-1, 2-diphenylethane-1-one (trade name: IRGACURE 651, manufactured by BASF corporation, having an absorption band at a wavelength of 200 to 380 nm) as a photopolymerization initiator, then, ultraviolet rays were irradiated until the viscosity (measurement conditions: BH viscometer No. fifth rotor, 10rpm, measurement temperature 30 ℃) reached about 20 pas, whereby a prepolymer composition (polymerization rate: 8%) in which a part of the monomer components were polymerized was obtained. Then, 0.120 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of a silane coupling agent (trade name: KBM-403, manufactured by shin-Etsu chemical Co., Ltd.) were added to the prepolymer composition and mixed to obtain an acrylic pressure-sensitive adhesive composition (a).

To the obtained acrylic adhesive composition (a), 1.4 parts of 2, 4-bis- [ {4- (4-ethylhexyloxy) -4-hydroxy } -phenyl ] -6- (4-methoxyphenyl) -1,3, 5-triazine (trade name: Tinosorb S, manufactured by BASF japan) and 0.2 parts of bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide (trade name: IRGACURE 819 having an absorption band at a wavelength of 200 to 450nm, manufactured by BASF japan) dissolved in butyl acrylate so that the solid content is 15% were added and stirred, thereby obtaining an acrylic adhesive composition (a).

The obtained acrylic pressure-sensitive adhesive composition (a) was applied to the release-treated surface of a long release film so that the thickness after formation of the pressure-sensitive adhesive layer became 150 μm, and then another release film was bonded to the surface of the pressure-sensitive adhesive composition layer. Then, the illuminance was 6.5mW/cm²The quantity of light was 1500mJ/cm²The pressure-sensitive adhesive composition layer is photocured by ultraviolet irradiation under the conditions described above, thereby forming a pressure-sensitive adhesive layer having an ultraviolet absorbing function.

6. Production of optical laminate

The release film was peeled off from one surface of the adhesive layer, and the transparent conductive layer surface of the touch sensor sheet a was attached to the peeled surface in a roll-to-roll manner while aligning the longitudinal direction. Next, the release film was peeled from the other surface of the adhesive layer, and the surface of the oriented cured layer B of the oriented cured layer laminate was attached to the peeled surface in a roll-to-roll manner in alignment with the longitudinal direction. Next, the PET substrate was peeled from the orientation cured layer laminate, and the surface of the polarizer laminate was bonded to the surface of the orientation cured layer B in a roll-to-roll manner while aligning the longitudinal direction. Next, the substrate was peeled from the polarizer laminate, and the retardation film laminate was attached to the surface of the polarizer by roll-to-roll alignment in the longitudinal direction. Next, the shrinkable film was peeled from the retardation film laminate to obtain a polarizing plate with a retardation layer, in which a touch sensor layer (first retardation layer and transparent conductive layer), an adhesive layer having an ultraviolet absorbing function, an oriented cured layer B (second retardation layer), a polarizer, and a retardation film C (third retardation layer) were laminated in this order. The bonding of each configuration except for the bonding of the touch sensor sheet a and the alignment cured layer B was performed using an acrylic adhesive.

In the optical laminate obtained, the angle formed by the absorption axis of the polarizer and the slow axis of the first phase difference layer was 25 °, and the angle formed by the absorption axis of the polarizer and the slow axis of the second phase difference layer was 80 °. The obtained optical laminate was evaluated for hue change and transmittance change according to the angle of polarized sunglasses. Fig. 3 shows the evaluation result of the hue change, and fig. 4 shows the evaluation result of the transmittance change.

< comparative example 1 >

1. Production of retardation film D

A long retardation film D was obtained by obliquely stretching a long film made of polycarbonate resin pellets. The retardation film D had a thickness of 67 μm, an in-plane retardation Re (550) of 125nm, an Re (450)/Re (550) of 1.06, an Re (650)/Re (550) of 0.97, a refractive index ellipsoid satisfying nx > ny ═ nz, and an angle formed between the slow axis and the longitudinal direction was 45 °.

2. Production of zero-phase-difference touch sensor layer

As the base material, a long norbornene-based cycloolefin film (product name "ZEONOR ZF 14" manufactured by Nippon Rayanus Co., Ltd., thickness: 40 μm) was used. The norbornene-based cycloolefin film had an in-plane retardation Re (550) of 1.7nm and a retardation Rth (550) in the thickness direction of 1.8 nm.

The norbornene-based cyclic olefin film is subjected to corona treatment to hydrophilize the surface. Then, a metal mesh (grid having a line width of 100 μm and a pitch of 1.5 mm) was formed on the film by screen printing using a silver paste (product name "RA FS 039" manufactured by Toyo Kogyo Co., Ltd.) and fired at 120 ℃ for 10 minutes to form a transparent conductive layer. Thus, a touch sensor layer with zero phase difference is obtained.

3. Production of optical laminate

An optical laminate was produced in the same manner as in example 1, except that a laminate of a touch sensor layer with a zero retardation and a retardation film D was produced instead of the laminate of the touch sensor sheet a and the oriented cured layer B, and the surface of the polarizer laminate was bonded to the surface of the retardation film D of the laminate. The obtained optical laminate was an optical laminate in which a zero-phase-difference touch sensor layer, an adhesive layer having an ultraviolet absorption function, a phase difference film D, a polarizer, and a phase difference film C were laminated in this order, and the angle formed by the absorption axis of the polarizer and the slow axis of the phase difference film D was 45 °. The obtained optical laminate was subjected to evaluation of change in hue and change in transmittance in the same manner as in example 1. The results are shown in FIGS. 3 and 4.

< comparative example 2 >

1. Production of retardation film E

In the same manner as in the production of the first retardation layer of example 1, a retardation film E having an in-plane retardation Re (550) of 100nm and an angle formed by the slow axis and the longitudinal direction of 45 ℃ was obtained.

2. Production of zero-phase-difference touch sensor layer

A touch sensor layer having a zero phase difference was obtained in the same manner as in comparative example 1.

3. Production of optical laminate

An optical laminate was produced in the same manner as in comparative example 1, except that the retardation film E was used instead of the retardation film D. The obtained optical laminate was an optical laminate in which a zero-phase-difference touch sensor layer, an adhesive layer having an ultraviolet absorption function, a phase difference film E, a polarizer, and a phase difference film C were laminated in this order, and the angle formed by the absorption axis of the polarizer and the slow axis of the phase difference film E was 45 °. The obtained optical laminate was subjected to evaluation of change in hue and change in transmittance in the same manner as in example 1. The results are shown in FIGS. 3 and 4.

< evaluation >

As can be seen from fig. 3: the curve plotted from the hue plots obtained by the spectrometry performed through the optical laminate of example 1 is smaller in the area inside or smaller in the variation width along the vertical axis than the curve plotted from the hue plots obtained by the spectrometry performed through the optical laminates of comparative examples 1 and 2. This means that: the light transmitted through the optical laminate of example 1 has a smaller change in hue depending on the angle of the polarizing sunglasses than the light transmitted through the optical laminates of comparative examples 1 and 2. The amplitude of the curve obtained by the transmittance measurement through the optical laminate of example 1 was smaller than the amplitude of the curve obtained by the transmittance measurement through the optical laminate of comparative example 2. This means that: the optical laminate of example 1 has a smaller change in transmittance with a change in angle of a polarizer simulating polarized sunglasses than the optical laminate of comparative example 2.

Industrial applicability

The optical laminate of the present invention is suitably used for an image display device (particularly, a liquid crystal display device).

Claims

1. An optical layered body comprising a touch sensor layer, a second phase difference layer, a polarizer, and a third phase difference layer laminated in this order from a viewing side, wherein the touch sensor layer comprises a first phase difference layer and a transparent conductive layer disposed on one side or both sides of the first phase difference layer,

wherein the touch sensor layer and the second phase difference layer are laminated with an adhesive layer having an ultraviolet absorbing function interposed therebetween,

the in-plane retardation Re1 of the first retardation layer satisfies Re1(450)/Re1(550) < 1.03, Re1(650)/Re1(550) > 0.97,

the in-plane retardation Re2 of the second retardation layer satisfies Re2(450)/Re2(550) of not less than 1.03, Re2(650)/Re2(550) of not more than 0.97,

wherein Re1(450) and Re2(450) represent in-plane retardation measured at 23 ℃ with light having a wavelength of 450nm, Re1(550) and Re2(550) represent in-plane retardation measured at 23 ℃ with light having a wavelength of 550nm, Re1(650) and Re2(650) represent in-plane retardation measured at 23 ℃ with light having a wavelength of 650nm,

an in-plane retardation Re1(550) of the first retardation layer is 105nm to 115nm, an in-plane retardation Re2(550) of the second retardation layer is 190nm to 260nm, an angle theta 1 formed by an absorption axis of the polarizer and a slow axis of the first retardation layer is 19 DEG to 35 DEG, and an angle theta 2 formed by an absorption axis of the polarizer and a slow axis of the second retardation layer is 77 DEG to 85 DEG,

or the in-plane retardation Re1(550) of the first retardation layer is 116nm to 125nm, the in-plane retardation Re2(550) of the second retardation layer is 200nm to 260nm, the angle theta 1 formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 DEG to 35 DEG, and the angle theta 2 formed by the absorption axis of the polarizer and the slow axis of the second retardation layer is 75 DEG to 85 DEG,

or the in-plane retardation Re1(550) of the first retardation layer is 136nm to 145nm, the in-plane retardation Re2(550) of the second retardation layer is 220nm to 270nm, the angle theta 1 formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 DEG to 31 DEG, and the angle theta 2 formed by the absorption axis of the polarizer and the slow axis of the second retardation layer is 75 DEG to 83 DEG,

either one of the refractive index ellipsoid of the first phase difference layer and the refractive index ellipsoid of the second phase difference layer satisfies nx > ny ═ nz > ny, and the other satisfies nx > ny ═ nz,

the refractive index ellipsoid of the third retardation layer satisfies a relationship of nx > nz > ny or nx > ny > nz.

2. The optical laminate according to claim 1, wherein the first retardation layer is a stretched polymer film, and the second retardation layer is an oriented cured layer of a liquid crystal compound.

3. The optical laminate according to claim 1 or 2, wherein the adhesive layer having an ultraviolet absorbing function has an average light transmittance of 5% or less at a wavelength of 300 to 400nm, an average light transmittance of 70% or more at a wavelength of 450 to 500nm, and an average light transmittance of 80% or more at a wavelength of 500 to 780 nm.

4. An image display device comprising the optical laminate according to any one of claims 1 to 3.

5. A method for producing the optical laminate according to any one of claims 1 to 3, comprising the steps of: the first long film constituting the touch sensor layer, the second long film constituting the second retardation layer, the polarizer and the third long film constituting the third retardation layer are continuously bonded to the adjacent films while being conveyed.