TW202334723A - Optical laminate and image display device that comprises, in sequence, a polarization element, a first optical compensation layer, a second optical compensation layer, and a third optical compensation layer - Google Patents

Abstract

The present invention provides an optical laminate that realizes an image display that reduces reflection luminance. An embodiment of the optical laminate according to the present invention comprises, in sequence, a polarizing element, a first optical compensation layer whose reflective index characteristics exhibit a relationship of nx > ny, a second optical compensation layer whose reflective index characteristics exhibit a relationship of nz > nx=ny, a third optical compensation layer whose reflective index characteristics exhibit a relationship of nx > ny. The reflective index characteristics of the first optical compensation layer and/or the third optical compensation layer exhibit the relationship of nx > ny ≥ nz. The in-plane retardations of the first optical compensation layer and the third optical compensation layer are each greater than 10nm and lower than 220nm. The direction of an absorption axis of the polarizing element and the direction of a slow axis of the first optical compensation layer intersect with each other in a manner of being substantially not orthogonal to each other. The first optical compensation layer, the second optical compensation layer, and the third optical compensation layer satisfy a specific equation (1).

Description

Optical laminated body and image display device

The present invention relates to an optical laminated body and an image display device.

Generally, in image display devices, various optical laminates composed of a combination of a polarizing element and an optical compensation film are used in order to compensate for optical characteristics suitable for the intended use. As such an optical laminated body, for example, it is proposed to have a polarizing element, a first birefringent layer as a λ/2 plate, a second birefringent layer as a λ/4 plate, and a refractive index characteristic showing nz>nx=ny in this order. An elliptical polarizing plate with a third birefringent layer (for example, see Patent Document 1). In addition, in an image display device, problems may arise such as reflection of external light or reflection of the background caused by the display device itself or a reflector (such as a touch panel part or metal wiring) used in the display device. In particular, organic EL panels have a highly reflective metal layer, so they are prone to problems such as external light reflection and background reflection. Therefore, it has been considered to arrange an optical laminate on the viewing side of the image display panel to reduce the reflection brightness of the image display device. However, even if the elliptically polarizing plate described in Patent Document 1 is used in an image display device, it is difficult to sufficiently reduce the reflection brightness, and there is still room for improvement in the reduction of reflection brightness. Prior technical literature patent documents

[Patent Document 1] Japanese Patent Application Laid-Open No. 2006-268007

[Problem to be solved by the invention]

The present invention was completed in order to solve the above-mentioned previous problems, and its main object is to provide an optical laminate that can realize an image display device capable of reducing reflection brightness. [Technical means to solve problems]

The optical laminated body according to the embodiment of the present invention sequentially includes: a polarizing element; a first optical compensation layer whose refractive index characteristics show the relationship nx>ny; a second optical compensation layer whose refractive index characteristics show the relationship nz>nx=ny; and The third optical compensation layer has a refractive index characteristic showing the relationship nx>ny. The refractive index characteristics of the above-mentioned first optical compensation layer and/or the above-mentioned third optical compensation layer show the relationship nx>ny≧nz. The in-plane phase difference Re ¹ (550) of the above-mentioned first optical compensation layer and the in-plane phase difference Re ³ (550) of the above-mentioned third optical compensation layer are 10 nm or more and 220 nm or less respectively. The absorption axis direction of the polarizing element intersects with the slow axis direction of the first optical compensation layer in a substantially non-orthogonal manner. The first optical compensation layer, the second optical compensation layer and the third optical compensation layer satisfy the following formula (1). [Number 1] (In formula (1), Rth ¹ (550) represents the phase difference in the thickness direction of the first optical compensation layer; Rth ² (550) represents the phase difference in the thickness direction of the second optical compensation layer; Rth ³ (550) represents the phase difference in the thickness direction of the second optical compensation layer. The phase difference in the thickness direction of the three optical compensation layers; Re ¹ (550) represents the in-plane phase difference of the first optical compensation layer; Re ³ (550) represents the in-plane phase difference of the third optical compensation layer). In one embodiment, the refractive index characteristics of the first optical compensation layer exhibit the relationship nz≧nx>ny, and the refractive index characteristics of the third optical compensation layer exhibit the relationship nx>ny≥nz. In one embodiment, the in-plane phase difference Re ³ (550) of the third optical compensation layer is 80 nm or more and 180 nm or less. In one embodiment, the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 50 nm or more. In one embodiment, the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 110 nm or more. In one embodiment, the phase difference Rth ² (550) in the thickness direction of the second optical compensation layer is -80 nm or more. In one embodiment, the refractive index characteristics of the first optical compensation layer show the relationship nz=nx>ny, and the refractive index characteristics of the third optical compensation layer show the relationship nx>ny=nz. In one embodiment, the refractive index characteristics of each of the first optical compensation layer and the third optical compensation layer show a relationship of nx>ny≧nz. In one embodiment, the in-plane phase difference Re ³ (550) of the third optical compensation layer is 50 nm or more and 180 nm or less. In one embodiment, the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 50 nm or more and 180 nm or less. In one embodiment, the phase difference Rth ² (550) in the thickness direction of the second optical compensation layer is -120 nm or less. In one embodiment, the refractive index characteristics of each of the first optical compensation layer and the third optical compensation layer show a relationship of nx>ny=nz. In one embodiment, the refractive index characteristics of the first optical compensation layer exhibit a relationship of nx>ny≧nz, and the refractive index characteristics of the third optical compensation layer exhibit a relationship of nz≧nx>ny. In one embodiment, the phase difference Rth ² (550) in the thickness direction of the second optical compensation layer is -70 nm or more. In one embodiment, the in-plane phase difference Re ³ (550) of the third optical compensation layer is 140 nm or less. In one embodiment, the in-plane phase difference Re ³ (550) of the third optical compensation layer is 45 nm or more. In one embodiment, the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 80 nm or more. In one embodiment, the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 180 nm or more. In one embodiment, the refractive index characteristics of the first optical compensation layer show the relationship nx>ny=nz, and the refractive index characteristics of the third optical compensation layer show the relationship nz=nx>ny. In one embodiment, among the above-mentioned first optical compensation layer and the above-mentioned third optical compensation layer, Re(450)/Re(550) of the optical compensation layer whose refractive index characteristics show the relationship nx>ny≧nz is less than 1. An image display device according to another aspect of the present invention includes an image display unit and the optical layered body. [Effects of the invention]

According to the optical laminate according to the embodiment of the present invention, an image display device capable of reducing reflection brightness can be realized.

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

(Definition of terms and symbols) The definitions of terms and symbols in this manual are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the refractive index in the plane becomes maximum (that is, the slow axis direction), and "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the direction of the slow axis). That is, the refractive index in the fast axis direction), "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference measured at 23°C using light of wavelength λ nm. For example, "Re(550)" is the in-plane phase difference measured at 23°C using light with a wavelength of 550 nm. Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is d(nm). Furthermore, in this specification, "the in-plane phase difference Re(λ) of the first optical compensation layer" may be referred to as "Re ¹ (λ)", and "the in-plane phase difference Re(λ) of the second optical compensation layer λ)" is called "Re ² (λ)", and "the in-plane phase difference Re(λ) of the third optical compensation layer" is called "Re ³ (λ)". (3) Phase difference in the thickness direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured at 23°C using light of wavelength λ nm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23°C using light with a wavelength of 550 nm. Rth(λ) is calculated by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm). Furthermore, in this specification, "the phase difference Rth (λ) in the thickness direction of the first optical compensation layer" is sometimes referred to as "Rth ¹ (λ)", and "the phase difference in the thickness direction of the second optical compensation layer Rth (λ)" is called "Rth ² (λ)", and "the phase difference Rth (λ) in the thickness direction of the third optical compensation layer" is called "Rth ³ (λ)". (4) Nz coefficient The Nz coefficient is calculated by Nz=Rth/Re. (5) Substantially parallel or orthogonal. The expressions "substantially orthogonal" and "approximately orthogonal" include the case where the angle between the two directions is 90°±3°. "Substantially parallel" and "approximately parallel""This expression includes the case where the angle formed by the two directions is 0°±3°. Furthermore, "intersecting in a manner that is not substantially orthogonal" means that the angle formed by the two directions is not substantially orthogonal and is not substantially parallel. More specifically, the expression "intersecting in a substantially non-orthogonal manner" includes the case where the angle between the two directions exceeds 3° and does not reach 87°, and the case where the angle exceeds 93° and does not reach 177°, Preferably it is 5° or more and 85° or less, or 95° or more and 175° or less.

A. Overall structure of optical laminate FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminated body 100 in the illustrated example includes in this order: a polarizing plate 40 including a polarizing element 41; a first optical compensation layer 10 having a refractive index characteristic showing the relationship nx>ny; and a first optical compensation layer 10 having a refractive index characteristic showing the relationship nz>nx=ny. the second optical compensation layer 20; and the third optical compensation layer 30 whose refractive index characteristics show the relationship nx>ny. The refractive index characteristics of the first optical compensation layer 10 and/or the third optical compensation layer 30 show the relationship nx>ny≧nz. The in-plane phase difference Re ¹ (550) of the first optical compensation layer 10 and the in-plane phase difference Re ³ (550) of the third optical compensation layer 30 are respectively 10 nm or more and 220 nm or less, preferably 30 nm or more and Below 200 nm. The absorption axis direction of the polarizing element 41 intersects with the slow axis direction of the first optical compensation layer 10 in a substantially non-orthogonal manner. The first optical compensation layer 10, the second optical compensation layer 20, and the third optical compensation layer 30 satisfy the following formula (1). [Number 2] (In formula (1), Rth ¹ (550) represents the phase difference in the thickness direction of the first optical compensation layer; Rth ² (550) represents the phase difference in the thickness direction of the second optical compensation layer; Rth ³ (550) represents the phase difference in the thickness direction of the second optical compensation layer. The phase difference in the thickness direction of the three optical compensation layers; Re ¹ (550) represents the in-plane phase difference of the first optical compensation layer; Re ³ (550) represents the in-plane phase difference of the third optical compensation layer). When the optical laminate having such a structure is applied to an image display device, the reflection brightness of the image display device can be reduced. Furthermore, when the optical laminate has an optical compensation layer (especially a λ/2 plate) with an in-plane retardation Re exceeding 220 nm, it is difficult to thin the optical compensation layer and reduce the amount of material used. Furthermore, an optical compensation layer (especially a λ/2 plate) with an in-plane phase difference Re exceeding 220 nm may have uneven alignment angles, and the absorption axis direction of the polarizing element may be offset from the slow axis direction of the optical compensation layer. increase. In addition, even if the axis deviation is of the same degree, the larger the phase difference value is, the greater the impact on optical compensation will be. Therefore, in the optical laminate provided with such an optical compensation layer (λ/2 plate), it is difficult to achieve thinning and to reduce the reflection brightness of the image display device as in the optical laminate according to the embodiment of the present invention.

The value calculated from the above formula (1) is, for example, -200 or more, preferably -150 or more, for example, 150 or less, preferably 100 or less. The refractive index characteristics of the second optical compensation layer 20 show the relationship nz>nx=ny. Here, "nx=ny" means not only the case where nx and ny are exactly the same, but also the case where nx and ny are substantially the same. The in-plane phase difference Re ² (550) of the second optical compensation layer 20 is, for example, 0 nm or more and 3.0 nm or less, preferably 0 nm. The phase difference Rth ² (550) of the second optical compensation layer 20 in the thickness direction is, for example, -200 nm or more and less than 0 nm, preferably -5 nm or less.

The refractive index characteristic of at least one of the first optical compensation layer 10 and the third optical compensation layer 30 shows the relationship nx>ny≧nz. When the refractive index characteristics of the third optical compensation layer 30 show the relationship nx>ny≧nz, the refractive index characteristics of the first optical compensation layer 10 typically show the relationship nz≧nx>ny or nx>ny≧nz. . In addition, when the refractive index characteristics of the first optical compensation layer 10 show the relationship nx>ny≧nz, the refractive index characteristics of the third optical compensation layer 30 typically show the relationship nz≧nx>ny, or nx>ny≧ nz relationship. Here, "nz=nx" means not only the case where nz and nx are exactly the same, but also the case where nz and nx are substantially the same. Furthermore, "ny=nz" means not only the case where ny and nz are exactly the same, but also the case where ny and nz are substantially the same.

The retardation Rth (550) in the thickness direction of the optical compensation layer, where the refractive index characteristics of the first optical compensation layer 10 and the third optical compensation layer 30 show the relationship nz=nx>ny, is, for example, -3.0 nm or more and 3.0 nm or less. , preferably 0 nm. The retardation Rth (550) in the thickness direction of the optical compensation layer in which the refractive index characteristics of the first optical compensation layer 10 and the third optical compensation layer 30 show the relationship nz>nx>ny is, for example, -60 nm or more and less than 0 nm, preferably -50 nm or more and -5 nm or less. At this time, the Nz coefficient of the optical compensation layer is, for example, -1.0 or more and -0.1 or less, preferably -0.5 or more and -0.2 or less. In the first optical compensation layer 10 and the third optical compensation layer 30, the phase difference Rth (550) in the thickness direction of the optical compensation layer whose refractive index characteristics show the relationship nx>ny≧nz is, for example, 10 nm or more and 220 nm or less. , preferably 30 nm or more and 210 nm or less. In this case, the Nz coefficient of the optical compensation layer is, for example, 0.9 or more and 1.1 or less.

In one embodiment, the Re(450)/Re(550) of the optical compensation layer whose refractive index characteristics show the relationship nx>ny≧nz in the first optical compensation layer 10 and the third optical compensation layer 30 does not reach 1, which means The sex value is above 0.8.

In one embodiment, the absorption axis direction of the polarizing element 41 intersects with the slow axis direction of the third optical compensation layer 30 in a substantially non-orthogonal manner.

The optical laminate may be in the form of a single sheet or in the form of a strip. In this specification, "strip shape" refers to an elongated shape with a length that is sufficiently long relative to the width, and includes, for example, an elongated shape with a length that is 10 times or more, preferably 20 times or more, the width. The long optical laminate can be rolled into a roll shape.

In practical applications, an adhesive layer (not shown) is provided on the side of the third optical compensation layer opposite to the polarizing plate, so that the optical laminate can be attached to the image display unit. Furthermore, it is preferable to temporarily adhere a release liner to the surface of the adhesive layer until the optical laminate is used. By temporarily attaching a release liner, the roll can be formed while protecting the adhesive layer.

Hereinafter, the specific combination of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer in the optical laminate will be described.

A-1. First optical laminate In one embodiment, the refractive index characteristics of the first optical compensation layer 10 show the relationship nz≧nx>ny, the refractive index characteristics of the second optical compensation layer 20 show the relationship nz>nx=ny, and the third optical compensation layer 30 The refractive index characteristics show the relationship nx>ny≧nz. The optical laminated body including such a combination of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer may be called a first optical laminated body. In the first optical laminated body, it is more preferable that the refractive index characteristics of the first optical compensation layer 10 show the relationship nz=nx>ny, and the refractive index characteristics of the third optical compensation layer 30 show the relationship nx>ny=nz. When the first optical compensation layer, the second optical compensation layer and the third optical compensation layer are combined in this way, the reflected brightness of the image display device can be further reduced.

In the first optical laminated body, the in-plane phase difference Re ¹ (550) of the first optical compensation layer 10 is preferably 40 nm or more, more preferably 50 nm or more, further preferably 110 nm or more, especially 140 nm. or above, preferably 195 nm or less. In the first optical layered body, when Re ¹ (550) is in the above range, the reflection brightness can be further reduced in the image display device. Furthermore, in the first optical layered body, the angle formed by the absorption axis direction of the polarizing element 41 and the slow axis direction of the first optical compensation layer 10 is preferably 5° or more and 80° or less, or 110° or more and 170° or less. , more preferably from 30° to 80°, further preferably from 50° to 80°.

In the first optical laminated body, the phase difference Rth ² (550) in the thickness direction of the second optical compensation layer 20 is preferably -100 nm or more, more preferably -80 nm or more, preferably -10 nm or less, and more preferably is below -40 nm. In the first optical layered body, when Rth ² (550) is in the above range, the reflected brightness can be further reduced in the image display device.

In the first optical layered body, the in-plane phase difference Re ³ (550) of the third optical compensation layer 30 is preferably 50 nm or more, more preferably 80 nm or more, further preferably 100 nm or more, and more preferably 195 nm. or less, more preferably 180 nm or less, still more preferably 140 nm or less. In the first optical laminated body, the phase difference Rth ³ (550) in the thickness direction of the third optical compensation layer 30 is preferably 50 nm or more, more preferably 80 nm or more, further preferably 100 nm or more, and more preferably 195 nm. nm or less, more preferably 180 nm or less, further preferably 140 nm or less. In the first optical layered body, when Re ³ (550) and/or Rth ³ (550) is within the above range, the reflected brightness can be further reduced in the image display device. Furthermore, in the first optical layered body, the angle formed by the absorption axis direction of the polarizing element 41 and the slow axis direction of the third optical compensation layer 30 is preferably 5° or more and 70° or less, or 110° or more and 170° or less. , more preferably from 10° to 60°, further preferably from 20° to 50°.

A-2. Second optical laminated body In one embodiment, the refractive index characteristics of the second optical compensation layer 20 show the relationship nz>nx=ny, and the refractive index characteristics of the first optical compensation layer 10 and the third optical compensation layer 30 show the relationship nx>ny≧nz. . The optical laminated body including such a combination of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer may be called a second optical laminated body. In the second optical laminated body, it is more preferable that the refractive index characteristics of each of the first optical compensation layer 10 and the third optical compensation layer 30 show the relationship nx>ny=nz. When the first optical compensation layer, the second optical compensation layer and the third optical compensation layer are combined in this way, the reflected brightness of the image display device can be further reduced.

In the second optical layered body, the in-plane phase difference Re ¹ (550) of the first optical compensation layer 10 is preferably 40 nm or more, more preferably 50 nm or more, further preferably 80 nm or more, and more preferably 195 nm. or less, more preferably 180 nm or less, still more preferably 130 nm or less, particularly preferably 110 nm or less. In the second optical laminated body, the phase difference Rth ¹ (550) in the thickness direction of the first optical compensation layer 10 is preferably 40 nm or more, more preferably 50 nm or more, further preferably 80 nm or more, and more preferably 195 nm. nm or less, more preferably 180 nm or less, further preferably 130 nm or less, particularly preferably 110 nm or less. In the second optical layered body, when Re ¹ (550) and/or Rth ¹ (550) is within the above range, the reflected brightness can be further reduced in the image display device. Furthermore, in the second optical laminated body, the angle formed by the absorption axis direction of the polarizing element 41 and the slow axis direction of the first optical compensation layer 10 is preferably 10° or more and 85° or less, or 100° or more and 160° or less. More preferably, it is 30° or more and 85° or less, and still more preferably, it is 50° or more and 85° or less.

In the second optical laminated body, the phase difference Rth ² (550) in the thickness direction of the second optical compensation layer 20 is preferably -150 nm or more, more preferably -50 nm or less, more preferably -100 nm or less, and further preferably Preferably, it is below -120 nm. In the second optical layered body, when Rth ² (550) is in the above range, the reflected brightness can be further reduced in the image display device.

In the second optical laminated body, the in-plane phase difference Re ³ (550) of the third optical compensation layer 30 is preferably 40 nm or more, more preferably 50 nm or more, further preferably 90 nm or more, and more preferably 200 nm. or less, more preferably 180 nm or less, still more preferably 140 nm or less, particularly preferably 120 nm or less. In the second optical laminated body, the phase difference Rth ³ (550) in the thickness direction of the third optical compensation layer 30 is preferably 40 nm or more, more preferably 50 nm or more, further preferably 90 nm or more, and more preferably 200 nm. nm or less, more preferably 180 nm or less, further preferably 140 nm or less, particularly preferably 120 nm or less. In the second optical layered body, when Re ³ (550) and/or Rth ³ (550) is within the above range, the reflected brightness can be further reduced in the image display device. Furthermore, in the second optical layered body, the angle formed by the absorption axis direction of the polarizing element 41 and the slow axis direction of the third optical compensation layer 30 is preferably 10° or more and 80° or less, or 110° or more and 170° or less. , more preferably from 20° to 70°, further preferably from 30° to 60°.

A-3. Third optical laminate In one embodiment, the refractive index characteristics of the first optical compensation layer 10 show the relationship nx>ny≧nz, the refractive index characteristics of the second optical compensation layer 20 show the relationship nz>nx=ny, and the third optical compensation layer 30 The refractive index characteristics show the relationship nz≧nx>ny. The optical laminated body including such a combination of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer may be called a third optical laminated body. In the third optical laminated body, it is more preferable that the refractive index characteristics of the first optical compensation layer 10 show the relationship nx>ny=nz, and the refractive index characteristics of the third optical compensation layer 30 show the relationship nz=nx>ny. When the first optical compensation layer, the second optical compensation layer and the third optical compensation layer are in this combination, the reflected brightness of the image display device can be further reduced.

In the third optical layered body, the in-plane phase difference Re ¹ (550) of the first optical compensation layer 10 is preferably 60 nm or more, more preferably 80 nm or more, further preferably 140 nm or more, especially 180 nm. or above, preferably 195 nm or less. In the third optical laminated body, the phase difference Rth ¹ (550) in the thickness direction of the first optical compensation layer 10 is preferably 60 nm or more, more preferably 80 nm or more, further preferably 140 nm or more, and particularly preferably 180 nm. nm or more, preferably 210 nm or less, more preferably 195 nm or less. In the third optical layered body, when Re ¹ (550) and/or Rth ¹ (550) is within the above range, the reflected brightness can be further reduced in the image display device. Furthermore, in the third optical layered body, the angle formed by the absorption axis direction of the polarizing element 41 and the slow axis direction of the first optical compensation layer 10 is preferably 10° or more and 80° or less, or 100° or more and 160° or less. , more preferably from 20° to 70°, further preferably from 30° to 60°.

In the third optical laminated body, the phase difference Rth ² (550) in the thickness direction of the second optical compensation layer 20 is preferably -90 nm or more, more preferably -70 nm or more, preferably -20 nm or less, and more preferably is below -40 nm. In the third optical layered body, when Rth ² (550) is within the above range, the reflected brightness can be further reduced in the image display device.

In the third optical laminated body, the in-plane phase difference Re ³ (550) of the third optical compensation layer 30 is preferably 40 nm or more, more preferably 45 nm or more, preferably 160 nm or less, more preferably 140 nm or less. , further preferably 100 nm or less, particularly preferably 80 nm or less. In the third optical layered body, when Re ³ (550) is in the above range, the reflected brightness can be further reduced in the image display device. Furthermore, in the third optical laminated body, the angle formed by the absorption axis direction of the polarizing element 41 and the slow axis direction of the third optical compensation layer 30 is preferably 5° or more and 70° or less, or 95° or more and 170° or less. , more preferably from 100° to 160°, further preferably from 110° to 150°.

Each member constituting the optical laminated body will be described below.

B.Polarizing plate B-1.Polarizing element As the polarizing element 41, any appropriate polarizing element can be used. For example, the resin film forming the polarizing element may be a single-layer resin film or a laminate of two or more layers.

Specific examples of the polarizing element composed of a single-layer resin film include: polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, para-ethylene-vinyl acetate copolymer-based partially saponified films, etc. Hydrophilic polymer membranes are dyed and stretched using dichroic substances such as iodine and dichroic dyes, and polyene-based alignment films such as dehydrated PVA or dehydrochloric acid-treated polyvinyl chloride are used. From the viewpoint of excellent optical properties, a polarizing element obtained by dyeing a PVA-based film with iodine and uniaxially stretching it can be preferably used.

The above-mentioned dyeing with iodine is performed, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 times or more and 7 times or less. Extending can be performed after dyeing or while dyeing. In addition, dyeing may be performed after stretching. As necessary, the PVA film is subjected to swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc. For example, by immersing the PVA film in water and washing it before dyeing, not only can stains or anti-adhesive agents on the surface of the PVA film be washed away, but the PVA film can also be swollen to prevent uneven dyeing.

Specific examples of polarizing elements obtained using a laminate include a laminate using a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and coating A polarizing element obtained by a laminate of PVA-based resin layers formed on the resin base material. A polarizing element obtained using a laminate of a resin base material and a PVA-based resin layer coated on the resin base material can be produced, for example, by applying a PVA-based resin solution to the resin base material. Drying to form a PVA-based resin layer on the resin base material to obtain a laminate of the resin base material and the PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer into a polarizing element. In one embodiment of the present invention, it is preferable to form a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of the resin base material. Stretching typically involves immersing the laminate in a boric acid aqueous solution and stretching it. Furthermore, the stretching may further include stretching the laminate in the air at a high temperature (for example, 95° C. or higher) before stretching in a boric acid aqueous solution, if necessary. Furthermore, in one embodiment of the present invention, it is preferable to subject the laminated body to a drying and shrinkage process in which the laminate is heated while being transported in the longitudinal direction to shrink the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes sequentially performing an air-assisted stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process on the laminate. By introducing auxiliary stretching, even when PVA is coated on thermoplastic resin, the crystallinity of PVA can be improved and high optical properties can be achieved. In addition, by improving the alignment of PVA in advance at the same time, when immersed in water in the subsequent dyeing step or stretching step, problems such as decrease in alignment or dissolution of PVA can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, compared with when the PVA-based resin layer does not contain a halide, the alignment disorder of polyvinyl alcohol molecules and the decrease in alignment can be suppressed. This can improve the optical properties of the polarizing element obtained by immersing the laminate in a liquid, such as dyeing treatment and water stretching treatment. Furthermore, by shrinking the laminated body in the width direction by drying and shrinking treatment, the optical properties can be improved. The obtained laminated body of the resin base material/polarizing element can be used directly (that is, the resin base material can be used as a protective layer of the polarizing element), or the resin base material can be peeled off from the laminated body of the resin base material/polarizing element. Use any suitable protective layer on the surface according to the purpose. Details of the manufacturing method of such a polarizing element are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. All descriptions in these publications are incorporated by reference into this specification.

The thickness of the polarizing element is, for example, 1 μm or more and 80 μm or less, preferably 1 μm or more and 15 μm or less, more preferably 1 μm or more and 12 μm or less, still more preferably 3 μm or more and 12 μm or less, especially preferably It is 3 μm or more and 8 μm or less. As long as the thickness of the polarizing element is within this range, curling during heating can be well suppressed and good appearance durability during heating can be obtained.

The polarizing element preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The single-element transmittance of the polarizing element is, for example, 41.5% or more and 46.0% or less, preferably 43.0% or more and 46.0% or less, more preferably 44.5% or more and 46.0% or less. The polarization degree of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

B-2.Protective layer The polarizing plate 40 may further include a protective layer. The protective layer is disposed on at least one surface of the polarizing element. In the illustrated example, the polarizing plate 40 includes a protective layer 42 provided on the viewing side of the polarizing element 41 .

The protective layer is formed of any appropriate film that can be used as a protective layer of the polarizing element. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, Polyimide series, polyether series, polystyrene series, polystyrene series, polynorphenyl series, polyolefin series, (meth)acrylic series, acetate series and other transparent resins. Furthermore, thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be used. wait. In addition, glassy polymers such as siloxane polymers can also be used. In addition, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01/37007) can also be used.

When the polarizing plate 40 has a protective layer located on the outermost surface of the image display device described below, the protective layer may also be subjected to surface treatments such as hard coating treatment, anti-reflection treatment, anti-stick treatment, and anti-glare treatment as needed.

The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm or more and 500 μm or less, further preferably 5 μm or more and 150 μm or less. Furthermore, when surface treatment is performed, the thickness of the protective layer includes the thickness of the surface treatment layer.

C. Second optical compensation layer In the illustrated example, the second optical compensation layer 20 is disposed between the first optical compensation layer 10 and the third optical compensation layer 30 . More specifically, the second optical compensation layer 20 is arranged adjacent to the first optical compensation layer 10 and the third optical compensation layer 30 respectively. In this specification, "arranged adjacently" means being laminated directly or laminated only through an adhesive layer (for example, an adhesive layer or an adhesive layer). That is, it means that no other optical functional layer is interposed between the first optical compensation layer 10 and the second optical compensation layer 20 and between the second optical compensation layer 20 and the third optical compensation layer 30 . The light transmittance of the second optical compensation layer 20 at a wavelength of 550 nm is preferably more than 80%, more preferably more than 85%, and further preferably more than 90%. The theoretical upper limit of light transmittance is 100%, but due to surface reflection due to the difference in refractive index between air and the retardation film, the upper limit of the achievable light transmittance is approximately 94%. The thickness of the second optical compensation layer 20 is set in such a way that desired optical properties can be obtained. The thickness of the second optical compensation layer 20 is typically 0.5 μm or more, typically 10 μm or less, preferably 8 μm or less, and further preferably 5 μm or less.

The refractive index characteristics of the second optical compensation layer 20 show the relationship nz>nx=ny as described above. A layer (film) showing the refractive index characteristic of nz>nx=ny is sometimes called a "positive C plate" or the like. The second optical compensation layer 20 is typically composed of a film including a liquid crystal material fixed in a vertical alignment (hereinafter referred to as a vertical alignment liquid crystal film). The liquid crystal material (liquid crystal compound) capable of vertical alignment can be a liquid crystal monomer or a liquid crystal polymer. The liquid crystal material (liquid crystal compound) preferably has polymerizability, and more preferably has photopolymerizability. Specific examples of the liquid crystal compound include liquid crystal compounds described in Japanese Patent Application Laid-Open No. 2002-333642 [0020] to [0028].

As a preparation method of such a vertically aligned liquid crystal film, any appropriate preparation method can be adopted. For example, after a coating liquid containing a liquid crystal material and a solvent is applied to a substrate (eg, a resin substrate), the coating film is heated to vertically align the liquid crystal material in a liquid crystal state. Thereafter, the vertically aligned liquid crystal material is irradiated with light (ultraviolet, etc.) to polymerize or crosslink the liquid crystal material, thereby fixing the alignment of the liquid crystal material. Thereby, a vertically aligned liquid crystal film is obtained. In addition, by adjusting the alignment treatment conditions (heating temperature, heating time), the Rth ² (550) of the second optical compensation layer can be adjusted to the above range. The heating temperature is, for example, 60°C or higher, preferably 70°C or higher, and is, for example, 300°C or lower, preferably 200°C or lower. The heating time is, for example, 10 seconds or more, preferably 20 seconds or more, for example, 2 hours or less, preferably 30 minutes or less. If the alignment treatment conditions are within the above range, vertical alignment can be stably formed.

D. First optical compensation layer The first optical compensation layer 10 is located between the polarizing plate 40 and the second optical compensation layer 20 and is arranged adjacent to the polarizing plate 40 . In the illustrated example, the first optical compensation layer 10 is arranged adjacent to the polarizing element 41 . That is, it means that no other optical functional layer is interposed between the polarizing plate 40 and the first optical compensation layer 10 . The range of the light transmittance of the first optical compensation layer 10 at a wavelength of 550 nm is the same as the range of the light transmittance of the above-mentioned second optical compensation layer 20 . The thickness of the first optical compensation layer 10 is set in such a way that desired optical properties can be obtained. The thickness of the first optical compensation layer 10 is typically 1 μm or more, preferably 4 μm or more, typically 200 μm or less, preferably 150 μm or less, more preferably 40 μm or less, and further preferably 30 μm or less. Below μm.

The refractive index characteristics of the first optical compensation layer 10 show the relationship nx>ny as described above, and typically show the relationship nz≧nx>ny, or the relationship nx>ny≧nz. A layer (film) showing the refractive index characteristic of nz=nx>ny is sometimes called a "negative A plate" or the like. A layer (film) showing the refractive index characteristics of nz>nx>ny is sometimes called a "positive B plate" or the like. A layer (film) showing refractive index characteristics of nx>ny=nz is sometimes called "positive A plate" or the like. A layer (film) showing refractive index characteristics of nx>ny>nz is sometimes called a "negative B plate" or the like. The first optical compensation layer 10 can be made of any appropriate material as long as it can obtain the above characteristics.

D-1. The first optical compensation layer whose refractive index characteristics show the relationship nz≧nx>ny When the refractive index characteristic of the first optical compensation layer 10 shows the relationship nz≧nx>ny, the first optical compensation layer 10 is typically composed of an extended film of a polymer film containing thermoplastic resin as the main component. As the thermoplastic resin, it is preferable to use a polymer showing negative birefringence. By using a polymer showing negative birefringence, a retardation film having a refractive index ellipsoid of nz≧nx>ny can be easily obtained. Here, "showing negative birefringence" means that when the polymer is aligned by stretching or the like, the refractive index in the stretching direction is relatively reduced. In other words, it refers to the increase in the refractive index in the direction orthogonal to the extension direction. Examples of polymers showing negative birefringence include polymers in which chemical bonds or functional groups with large polarization anisotropy, such as aromatic rings or carbonyl groups, are introduced into side chains. Specific examples include acrylic resin, styrene resin, maleimide resin, and the like.

The acrylic resin can be obtained, for example, by addition polymerization of an acrylate monomer. Examples of the acrylic resin include polymethyl methacrylate (PMMA), polybutyl methacrylate, and polycyclohexyl methacrylate.

The above-mentioned styrene-based resin can be obtained, for example, by addition polymerization of styrene-based monomers. Examples of the styrene-based monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, and p-aminostyrene. , p-carboxystyrene, p-phenylstyrene, 2,5-dichlorostyrene, p-tert-butylstyrene.

The above-mentioned maleimide-based resin can be obtained, for example, by addition polymerization of a maleimide-based monomer. Examples of maleimide-based monomers include N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2- Methylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N-(2-propylphenyl)maleimide, N-(2-isopropyl) phenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-dipropylphenyl)maleimide, N- (2,6-diisopropylphenyl)maleimide, N-(2-methyl-6-ethylphenyl)maleimide, N-(2-chlorophenyl)maleimide Imide, N-(2,6-dichlorophenyl)maleimide, N-(2-bromophenyl)maleimide, N-(2,6-dibromophenyl)maleimide Leimide, N-(2-biphenyl)maleimide, N-(2-cyanophenyl)maleimide.

In the above-mentioned addition polymerization, the birefringence characteristics of the obtained resin can also be controlled by substituting side chains after polymerization, or performing maleyl imidization or grafting reactions.

The above-mentioned polymer showing negative birefringence can also be copolymerized with other monomers. By copolymerizing other monomers, brittleness, formability, and heat resistance can be improved. Examples of the other monomer include: ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, 1 -Olefins such as hexene; acrylonitrile; (meth)acrylates such as methyl acrylate and methyl methacrylate; maleic anhydride; vinyl esters such as vinyl acetate.

When the polymer showing negative birefringence is a copolymer of the above styrenic monomer and the above other monomer, the blending rate of the styrenic monomer is preferably 50 mol% to 80 mol%. When the polymer showing negative birefringence is a copolymer of the above-mentioned maleimine monomer and the above-mentioned other monomer, the blending rate of the maleimine monomer is preferably 2 mol% to 50 mol%. Ear%. By blending within this range, a polymer film excellent in toughness and formability can be obtained.

As the polymer showing negative birefringence, styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-(meth)acrylate copolymer, styrene-maleic anhydride copolymer can be preferably used. Imine copolymer, vinyl ester-maleimine copolymer, olefin-maleimine copolymer, etc. These can be used individually or in combination of 2 or more types. These polymers can exhibit high negative birefringence and have excellent heat resistance. These polymers are available from NOVA Chemicals Japan and Arakawa Chemical Industry Co., Ltd., for example.

As the polymer showing negative birefringence, a polymer having a repeating unit represented by the following general formula (I) can also be preferably used. This kind of polymer can show higher negative birefringence and has better heat resistance and mechanical strength. Such a polymer can be obtained, for example, by using N-phenyl-substituted maleimide, which introduces at least a phenyl group having a substituent at the ortho position as a starting material. It is formed from the N substituent of the maleimide monomer. [Chemical 1]

In the above general formula (I), R ₁ to R ₅ each independently represent hydrogen, a halogen atom, a carboxylic acid, a carboxylic acid ester, a hydroxyl group, a nitro group or a linear or branched alkyl group having 1 to 8 carbon atoms or Alkoxy group (where R ₁ and R ₅ are not hydrogen atoms at the same time), R ₆ and R ₇ represent hydrogen or a linear or branched alkyl group or alkoxy group with a carbon number of 1 to 8, n represents 2 or more an integer.

The polymer showing negative birefringence is not limited to the above. For example, a cyclic olefin-based copolymer disclosed in Japanese Patent Application Laid-Open No. 2005-350544 and the like can also be used. Furthermore, a composition containing a polymer and inorganic fine particles disclosed in Japanese Patent Laid-Open No. 2005-156862, Japanese Patent Laid-Open No. 227427, etc. can also be preferably used. In addition, as a polymer showing negative birefringence, one type may be used alone, or two or more types may be mixed and used. Furthermore, they can also be used by modifying them by copolymerization, branching, cross-linking, molecular terminal modification (or capping), stereoregular modification, etc.

As a method of forming such a polymer film, any appropriate forming method can be used. Molding conditions can be appropriately set depending on the composition or type of resin used, the molding processing method, and the like.

The retardation film (stretched film) of the first optical compensation layer corresponding to the refractive index characteristic showing the relationship nz≧nx>ny can be obtained by stretching the above-mentioned polymer film under any appropriate stretching conditions. Specific examples of the stretching method include a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, and a longitudinal and transverse simultaneous biaxial stretching method. The longitudinal uniaxial stretching method, the longitudinal and transverse sequential biaxial stretching method, and the longitudinal and transverse simultaneous biaxial stretching method can be preferably used. For the above-mentioned polymer showing negative birefringence, since the refractive index in the stretching direction is relatively reduced as described above, when the longitudinal uniaxial stretching method is used, the polymer film has a fast axis in the transport direction (corresponding to the transport direction). The refractive index in the direction orthogonal to the direction becomes nx). In the case of the longitudinal and transverse sequential biaxial stretching method or the longitudinal and transverse simultaneous biaxial stretching method, both the conveying direction and the width direction can become the slow axis according to the ratio of the longitudinal and transverse stretching magnifications. Specifically, when the stretch ratio in the longitudinal (conveyance) direction is relatively increased, the transverse (width) direction becomes the slow axis; when the stretch ratio in the transverse (width) direction is relatively increased, the longitudinal (conveyance) direction becomes is the slow axis.

In addition, by adjusting the thickness of the polymer film (original film thickness), stretching temperature, and stretching ratio, Re ¹ (550) and Rth ¹ (550) of the first optical compensation layer can be adjusted to the above ranges. The thickness of the polymer film (original sheet thickness) is typically 5 μm or more, preferably 10 μm or more, and is typically 50 μm or less, preferably 40 μm or less. The stretching temperature (the temperature in the stretching oven when stretching the polymer film) is preferably near the glass transition temperature (Tg) of the polymer film. Specifically, (Tg-10)°C to (Tg+30)°C is preferred, Tg to (Tg+25)°C is more preferred, and (Tg+5)°C to (Tg+20)°C is particularly preferred. When the stretching temperature is too low, the phase difference value or the direction of the slow axis may become uneven, or the polymer film may crystallize (white turbidity). On the other hand, when the stretching temperature is too high, the polymer film may melt or the phase difference may become insufficiently expressed. The elongation temperature is typically 120°C or more and 170°C or less. In addition, the glass transition temperature can be calculated|required by the DSC method based on JIS K 7121-1987. The stretching ratio can be set to any appropriate value according to the composition of the polymer film, the type of volatile components, the residual amount of volatile components, etc., the required phase difference value, etc. Preferably it is 1.1 times or more and 3.0 times or less. In addition, the feed speed during stretching is preferably 0.5 m/min to 20 m/min from the viewpoint of mechanical accuracy and stability of the stretching device.

The method of obtaining a retardation film using a polymer showing negative birefringence has been described above, but the retardation film can also be obtained using a polymer showing positive birefringence. As a method of obtaining a retardation film using a polymer showing positive birefringence, for example, those disclosed in Japanese Patent Laid-Open Nos. 2000-231016, 2000-206328, and 2002-207123 can be used. An extension method for increasing the refractive index in the thickness direction is disclosed. A specific example is a method of attaching a heat shrinkable film to one or both sides of a film containing a polymer showing positive birefringence and subjecting it to heat treatment. By shrinking the heat-shrinkable film in the length direction and width direction due to the shrinkage force generated by the heat treatment, the refraction in the thickness direction can be increased, and nz>nx>ny can be obtained. The retardation film of the refractive index ellipsoid.

As mentioned above, the first optical compensation layer whose refractive index characteristics show the relationship nz≧nx>ny can also be manufactured using a polymer showing negative birefringence. Generally speaking, when using a polymer showing positive birefringence, it has the advantage of having a wide variety of polymers to choose from; when using a polymer showing negative birefringence, it is better to use a polymer showing positive birefringence. Compared with this case, the stretching method has an advantage in that a retardation film with excellent uniformity in the slow axis direction can be easily obtained.

D-2. The first optical compensation layer whose refractive index characteristics show the relationship nx>ny≧nz When the refractive index characteristic of the first optical compensation layer 10 shows the relationship nx>ny≧nz, the first optical compensation layer 10 is typically composed of a retardation film (an extended film of a polymer film). As the resin forming the polymer film, any appropriate resin can be used. Specific examples include resins constituting a positive birefringent film such as nordecene-based resin, polycarbonate-based resin, cellulose-based resin, polyvinyl alcohol-based resin, and polyurethane-based resin. Among these, nordecene-based resins and polycarbonate-based resins are preferred.

The above-mentioned norvinyl resin is a resin obtained by polymerizing a norvinyl monomer as a polymerization unit. Examples of the norphenylene-based monomer include: norphenylene and its alkyl and/or alkylene substituents, such as 5-methyl-2-norphenylene, 5-dimethyl-2- Norphene, 5-ethyl-2-norphene, 5-butyl-2-norphene, 5-ethylidene-2-norphene, and other halogen and other polar substituents; bicyclic Pentadiene, 2,3-dihydrodicyclopentadiene, etc.; dimethyloctahydronaphthalene, its alkyl and/or alkylene substituents, and halogen and other polar substituents, such as 6-methyl- 1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4:5,8-dimethyl bridge -1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethylene-1,4:5,8-dimethyl bridge-1,4,4a,5,6, 7,8,8a-octahydronaphthalene, 6-chloro-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-cyanohydrin Base-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4:5,8-dimethyl Bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4:5,8-dimethyl bridge-1,4,4a,5 , 6,7,8,8a-octahydronaphthalene, etc.; trimers to tetramers of cyclopentadiene, such as 4,9:5,8-dimethyl bridge-3a,4,4a,5,8 ,8a,9,9a-octahydro-1H-fluorine, 4,11:5,10:6,9-trimethyl bridge-3a,4,4a,5,5a,6,9,9a,10,10a, 11,11a-Dodecahydro-1H-cyclopentanthracene. The above-mentioned norvinyl resin may also be a copolymer of a norvinyl monomer and other monomers.

The polycarbonate resin includes, for example, a structural unit derived from a fluorine-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from an alicyclic diol, alicyclic dimethanol, The structural unit of at least one dihydroxy compound in the group consisting of diethylene glycol, triethylene glycol or polyethylene glycol, and alkylene glycol or spiro glycol. The polycarbonate resin preferably contains a structural unit derived from a fluorine-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from spirodiol. The polycarbonate resin may contain structural units derived from other dihydroxy compounds as necessary. Furthermore, details of the polycarbonate-based resin that can be preferably used in the present invention are described in, for example, Japanese Patent Application Laid-Open No. 2014-10291, Japanese Patent Application Laid-Open No. 2014-26266, and Japanese Patent Application Laid-Open No. 2015-212816 The descriptions in the publications, Japanese Patent Application Laid-Open No. 2015-212817 and Japanese Patent Application Laid-Open No. 2015-212818 are incorporated by reference in this specification.

The retardation film (stretched film) of the first optical compensation layer corresponding to the refractive index characteristic showing the relationship nx>ny≧nz can be obtained by stretching the above-mentioned polymer film under any appropriate stretching conditions. Specifically, by appropriately selecting the type of polymer, stretching conditions (such as stretching temperature, stretching ratio, stretching direction), and stretching method (such as longitudinal uniaxial stretching), it is possible to obtain the above-mentioned required optical properties (such as refractive index). Characteristics, in-plane retardation, thickness direction retardation) retardation film (first optical compensation layer). In particular, by adjusting the thickness of the polymer film (original film thickness), stretching temperature and stretching ratio, Re ¹ (550) and Rth ¹ (550) of the first optical compensation layer can be adjusted to the above range. The thickness of the polymer film (original sheet thickness) is typically 5 μm or more, preferably 10 μm or more, typically 210 μm or less, preferably 160 μm or less, more preferably 50 μm or less, and still more preferably is below 40 μm. The elongation temperature is preferably from 120°C to 170°C, more preferably from 130°C to 160°C. The extension ratio is preferably 1.1 times to 3.0 times, more preferably 1.3 times to 2.0 times.

E. Third optical compensation layer The third optical compensation layer 30 is arranged on the opposite side of the first optical compensation layer 10 relative to the second optical compensation layer 20 . In the illustrated example, the third optical compensation layer 30 is arranged adjacent to the second optical compensation layer 20 . That is, it means that no other optical functional layer is interposed between the second optical compensation layer 20 and the third optical compensation layer 30 . The range of the light transmittance at a wavelength of 550 nm of the third optical compensation layer 30 is the same as the range of the light transmittance of the above-mentioned first optical compensation layer 10 . The thickness of the third optical compensation layer 30 is set in such a way that required optical properties can be obtained. The thickness of the third optical compensation layer 30 is typically 1 μm or more, preferably 4 μm or more, typically 200 μm or less, preferably 150 μm or less, more preferably 40 μm or less, and still more preferably 30 μm. the following.

The refractive index characteristics of the third optical compensation layer 30 show the relationship nx>ny as described above, and typically show the relationship nz≧nx>ny, or the relationship nx>ny≧nz. When the refractive index characteristics of the third optical compensation layer 30 show the relationship of nz≧nx>ny, the third optical compensation layer 30 and the first optical compensation layer described in the above item D-1 (refractive index characteristics; nz≧nx> ny) are formed similarly. When the refractive index characteristics of the third optical compensation layer 30 show the relationship of nx>ny≧nz, the third optical compensation layer 30 and the first optical compensation layer described in the above item D-2 (refractive index characteristics; nx>ny≧ nz) are formed similarly.

F. Image display device The optical laminated body described in the above-mentioned items A to E can be applied to an image display device. Therefore, one embodiment of the present invention also includes an image display device using such an optical layered body. Representative examples of image display devices include liquid crystal display devices and organic EL display devices. In particular, the above-mentioned optical laminate can reduce the reflected brightness of the image display device, so it can be preferably applied to the organic EL display device. An image display device according to an embodiment of the present invention includes an image display unit and the optical laminate described in items A to E above. The image display device typically includes an image display panel including an image display unit, and the above-described optical layered body disposed on the viewing side. Furthermore, the image display device is sometimes called an optical display device, the image display panel is sometimes called an optical display panel, and the image display unit is sometimes called an optical display unit. Example

Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to these examples. The measurement method of each characteristic is as follows.

(1) Measurement of phase difference values Using KOBRA-WPR manufactured by Oji Instruments, the phase difference values of the first optical compensation layer, the second optical compensation layer and the third optical compensation layer used in the examples and comparative examples were automatically measured. Measure. The measurement wavelength is 450 nm or 550 nm, and the measurement temperature is 23°C. (2) Reflection brightness (brightness) The reflection brightness of the image display devices obtained in the Examples and Comparative Examples was measured at intervals of 60° at a polar angle using a luminance meter (manufactured by Instrument Systems, trade name "DMS505"). The brightness (unit: cd/m ² ) was measured at an azimuth angle of 5°, and the maximum value was taken as the reflected brightness. The results are shown in Tables 1 to 4.

<Preparation of retardation film (positive C plate) with refractive index characteristics nz>nx=ny><<Manufacturing Example 1>> The following chemical formula (II) (numbers 65 and 35 in the formula represent the monomer units) %, expressed as a block polymer for convenience: 20 parts by mass of a side chain type liquid crystal polymer shown with a weight average molecular weight of 5000) and 80 parts by mass of a polymerizable liquid crystal showing a nematic liquid crystal phase (manufactured by BASF: trade name PaliocolorLC242) 5 parts by mass and a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) were dissolved in 200 parts by mass of cyclopentanone to prepare a liquid crystal coating liquid. [Chemicalization 2] Then, the coating liquid was coated on the base film (norphene-based resin film: manufactured by Zeon Corporation of Japan, trade name "ZEONEX") using a bar coater, and then heated and dried at 80° C. for 4 minutes. Align the liquid crystal. By irradiating the liquid crystal layer with ultraviolet rays, the liquid crystal layer is hardened and a retardation film (thickness: 2 μm) is formed on the base material. The refractive index characteristics of the retardation film thus obtained show the relationship of nz>nx=ny. The in-plane phase difference Re (550) of the retardation film (positive C plate) and the phase difference Rth (550) in the thickness direction are shown in Tables 1 to 4. <<Manufacturing Example 2-10>> A phase difference film was obtained in the same manner as in Manufacturing Example 1, except that the alignment treatment conditions were changed so that the retardation Rth (550) in the thickness direction became the values shown in Tables 1 to 4. (Positive C plate).

<Production of retardation film (negative A plate) with refractive index characteristics nz=nx>ny> ＜＜Manufacturing Example 11＞＞ Using a single-screw extruder and a T-die, styrene-maleic anhydride copolymer (manufactured by NOVA Chemicals Japan, trade name "Dylark D232") granular resin is extruded at 270°C, and the sheet is cooled by a cooling roller. The molten resin in the shape was cooled to obtain a film with a thickness of 40 μm. Using a roller stretching machine, the film was longitudinally stretched in the conveying direction at a temperature of 130° C. and a stretching ratio of 1.9 times to obtain a retardation film having a fast axis in the conveying direction. The refractive index characteristics of the retardation film thus obtained show the relationship of nz=nx>ny. The in-plane phase difference Re (550), the thickness direction phase difference Rth (550) and Re (450)/Re (550) of the retardation film (negative A plate) are shown in Table 1 and Table 3. ＜＜Manufacturing Example 12-16＞＞ The film before stretching (thickness: 40 μm) obtained in the same manner as in Production Example 11 was longitudinally stretched at 130° C. so that the in-plane phase difference Re (550) became the values shown in Table 1 and Table 3, and the phase difference was obtained. membrane (negative A plate).

＜Preparation of retardation film (positive B plate) with refractive index characteristics nz＞nx＞ny＞ ＜＜Manufacturing Example 17＞＞ The film before stretching (thickness: 40 μm) obtained in the same manner as in Production Example 11 was prepared so that the in-plane phase difference Re (550) and the phase difference Rth (550) in the thickness direction became the values shown in Table 1 and Table 3. The fixed end was stretched longitudinally in the conveyance direction at 130°C to obtain a retardation film. The refractive index characteristics of the retardation film thus obtained show the relationship of nz>nx>ny. The in-plane phase difference Re (550), the thickness direction phase difference Rth (550), Re (450)/Re (550) and the Nz coefficient of the retardation film (positive B plate) are shown in Table 1 and Table 3.

＜Preparation of retardation film (positive A plate) with refractive index characteristics nx＞ny=nz＞ ＜＜Manufacturing Example 18＞＞A long olefin-based resin film (manufactured by Zeon Corporation of Japan, trade name Zeonor, thickness 40 μm and a photoelastic coefficient of 3.10×10 ^-12 m ² /N), and the free end is longitudinally extended to 1.3 times at 135°C to obtain a retardation film with a thickness of 35 μm. The refractive index characteristics of the retardation film thus obtained show the relationship nx>ny=nz. The in-plane phase difference Re (550), the thickness direction phase difference Rth (550), Re (450)/Re (550) and the Nz coefficient of the retardation film (positive A plate) are shown in Tables 1 to 4. ＜＜Manufacture Example 19-29＞＞ The nordecene-based resin film (manufactured by Zeon Corporation of Japan, trade name Zeonor, thickness: 40 μm) was set to one of the values shown in Tables 1 to 4 with an in-plane phase difference Re (550). The free end is stretched longitudinally at 135°C to obtain a retardation film (positive A plate). In addition, the Re (550) of the retardation film of Production Example 28 is 270 nm, and it functions as a λ/2 plate. Furthermore, the retardation film of Production Example 29 has Re (550) of 135 nm and functions as a λ/4 plate.

＜＜Production Example 30＞＞Bis[9-(2-phenoxycarbonylethyl)fluoride was put into a batch polymerization apparatus including two vertical reactors equipped with stirring blades and a reflux cooler controlled at 100°C. -9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 parts by mass (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by mass (0.298 mol), and 1.19×10 ^-2 parts by mass (6.78×10 ^-5 mol) of calcium acetate monohydrate as a catalyst. After replacing the reactor with nitrogen under reduced pressure, the reactor was heated using a heating medium, and stirring was started when the internal temperature reached 100°C. 40 minutes after the temperature rise starts, the internal temperature reaches 220°C and is controlled to maintain the temperature. At the same time, pressure reduction begins. After reaching 220°C, it takes 90 minutes to reach 13.3 kPa. The phenol vapor produced by the polymerization reaction is introduced into a reflux cooler at 100°C, a certain amount of monomer components contained in the phenol vapor is returned to the reactor, and the uncondensed phenol vapor is introduced into a reflux cooler at 45°C. be recycled in the container. Nitrogen gas was introduced into the first reactor, and after the pressure was temporarily restored to atmospheric pressure, the oligomerized reaction liquid in the first reactor was moved to the second reactor. Then, the temperature rise and pressure reduction in the second reactor were started, and it took 50 minutes to reach the internal temperature of 240°C and the pressure of 0.2 kPa. Afterwards, polymerization is carried out until the specified stirring power is reached. When the specified power is reached, nitrogen gas is introduced into the reactor for repressurization, the generated polyester carbonate resin is extruded into water, and the strands are cut to obtain pellets. The obtained polyester carbonate resin (pellet) was vacuum dried at 80°C for 5 hours, and then used with a single-screw extruder (manufactured by Toshiba Machinery Co., Ltd., barrel setting temperature: 250°C) and a T-die (width: 200 mm, set temperature: 250℃), cooling roller (set temperature: 120~130℃) and film forming device of the winding machine to produce long strips of resin film with a thickness of 130 μm. The free end of the obtained long resin film was lengthwise extended to 1.3 times at 140°C to obtain a retardation film (positive plate A) with a thickness of 115 μm. ＜＜Manufacture Example 31-34＞＞The resin film before stretching (thickness: 130 μm) obtained in the same manner as in Production Example 30 was prepared so that the in-plane phase difference Re (550) became the values shown in Tables 1 to 4. The free end was stretched longitudinally at 140°C to obtain a retardation film (positive A plate). Furthermore, the retardation film of Production Example 34 has Re (550) of 140 nm and functions as a λ/4 plate.

＜Preparation of retardation film (negative B plate) with refractive index characteristics nx＞ny＞nz＞ ＜＜Manufacturing Example 35-38＞＞ The in-plane phase difference Re (550) and the phase difference Rth (550) in the thickness direction of the nordecene-based resin film (manufactured by Zeon Corporation of Japan, trade name Zeonor, thickness 40 μm) were set to the values shown in Tables 1 to 3 The fixed end is stretched laterally at 135°C to obtain a retardation film. The refractive index characteristics of the retardation film thus obtained show the relationship nx>ny>nz. The in-plane phase difference Re (550), the thickness direction phase difference Rth (550), Re (450)/Re (550) and the Nz coefficient of the retardation film (negative B plate) are shown in Tables 1 to 3.

＜Production of Polarizing Plate＞ ＜＜Manufacturing Example 39＞＞ As the thermoplastic resin base material, a long amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100 μm) with a Tg of about 75°C is used. Implement corona treatment. A mixture of polyvinyl alcohol (degree of polymerization: 4200, saponification degree: 99.2 mol%) and acetate-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gohsefimer") at a ratio of 9:1 After adding 13 parts by mass of potassium iodide to 100 parts by mass of PVA-based resin, the resultant was dissolved in water to prepare a PVA aqueous solution (coating liquid). The above-mentioned PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm to prepare a laminate. The obtained laminate was uniaxially stretched to 2.4 times in the longitudinal direction (length direction) in an oven at 130° C. (air-assisted stretching treatment). Next, the laminated body was immersed in an insolubilization bath (a boric acid aqueous solution prepared by mixing 4 parts by mass of boric acid with respect to 100 parts by mass of water) with a liquid temperature of 40° C. for 30 seconds (insolubilization treatment). Then, in a dyeing bath with a liquid temperature of 30°C (an iodine aqueous solution prepared by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by mass of water), the single-element transmittance (Ts) of the finally obtained polarizing element was measured. ) to reach the desired value, while soaking for 60 seconds (dyeing process). Next, it was immersed in a crosslinking bath (a boric acid aqueous solution prepared by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with respect to 100 parts by mass of water) with a liquid temperature of 40° C. for 30 seconds (crosslinking treatment). Thereafter, the laminated body was immersed in a boric acid aqueous solution with a liquid temperature of 70° C. (boric acid concentration: 4 wt%, potassium iodide concentration: 5 wt%), while being placed between rollers with different circumferential speeds in the longitudinal direction (length direction). Uniaxial stretching (water stretching treatment) is performed at a stretching ratio of 5.5 times. Thereafter, the laminated body was immersed in a cleaning bath (an aqueous solution prepared by mixing 4 parts by mass of potassium iodide with respect to 100 parts by mass of water) having a liquid temperature of 20° C. (washing treatment). Thereafter, while drying in an oven maintained at about 90°C, it was brought into contact with a SUS heated roller whose surface temperature was maintained at about 75°C (drying shrinkage treatment). In this way, a polarizing element with a thickness of approximately 5 μm is formed on the resin base material, and a laminate having a resin base material/polarizing element structure is obtained. An HC-TAC film (thickness: 20 μm) was bonded as a protective layer on the surface of the polarizing element of the obtained laminate (the surface opposite to the resin base material). Then, the resin base material is peeled off to obtain a polarizing plate having a protective layer/polarizing element structure.

＜Preparation of image display panel (OLED panel)＞ After taking out the organic EL panel with the polarizing film attached to it from the organic EL display (manufactured by Samsung, product name "Galaxy A41"), the polarizing film is removed to obtain an image display panel (OLED panel).

[Example 1-8] The retardation film of the Production Example shown in Table 1 and the polarizing plate of Production Example 39 were punched into sizes corresponding to the image display units. Furthermore, as shown in Table 1, the retardation films of each production example are classified into a first retardation film corresponding to the first optical compensation layer, a second retardation film corresponding to the second optical compensation layer, and a second retardation film corresponding to the second optical compensation layer. The third phase difference film of the three optical compensation layers. Then, on the viewing side of the OLED panel, a third retardation film (third optical compensation layer), a second retardation film (second optical compensation layer), a first retardation film (first optical compensation layer) and Polarizing plate. The lamination is performed so that the angle between the absorption axis direction of the polarizing element and the slow axis direction of the optical compensation layer (each of the first optical compensation layer and the third optical compensation layer) becomes the value in Table 1. In this way, an image display device is produced. Then, the image display device was subjected to the above-mentioned reflection brightness measurement.

Table 1 No. Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 first optical compensation layer (First retardation film) Manufacturing example Manufacturing example 11 Manufacturing example 12 Manufacturing example 13 Manufacturing example 14 Manufacturing example 14 Manufacturing example 15 Manufacturing example 17 Manufacturing example 12 refractive index properties nz=nx>ny nz＞nx＞ny nz=nx>ny Re ¹ (550)[nm] 100 190 40 70 70 140 50 190 Rth ¹ (550)[nm] 0 0 0 0 0 0 -15 0 Nz coefficient - - - - - - -0.3 - Re ¹ (450)/Re ¹ (550) 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 The angle between the absorption axis direction and the slow axis direction [°] 80 80 35 155 45 95 5 80 second optical compensation layer (Second retardation film) Manufacturing example Manufacturing example 1 Manufacturing example 1 Manufacturing example 2 Manufacturing example 2 Manufacturing example 2 Manufacturing example 4 Manufacturing example 2 Manufacturing example 1 refractive index properties nz>nx=ny Re ² (550)[nm] 0 0 0 0 0 0 0 0 Rth ² (550)[nm] -60 -60 -30 -30 -30 -90 -30 -60 third optical compensation layer (Third phase difference film) Manufacturing example Manufacturing example 18 Manufacturing example 19 Manufacturing example 20 Manufacturing example 21 Manufacturing example 22 Manufacturing example 19 Manufacturing example 35 Manufacturing example 30 refractive index properties nx>ny=nz nx＞ny＞nz nx>ny=nz Re ³ (550)[nm] 110 120 100 190 70 120 130 120 Rth ³ (550)[nm] 110 120 100 190 70 120 143 120 Nz coefficient 1.0 1.0 1.0 1.0 1.0 1.0 1.1 1.0 Re ³ (450)/Re ³ (550) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.8 The angle between the absorption axis direction and the slow axis direction [°] 40 30 45 40 45 140 45 30 (Rth ¹ - Re ¹ /2) + (Rth ² ) + (Rth ³ - Re ³ /2) -55 -95 0 30 -30 -100 8 -95 Brightness (cd/m ² ) 0.45 0.44 0.59 0.74 0.65 0.55 0.71 0.41

[Example 9-15] Except that the first retardation film (first optical compensation layer), the second retardation film (second optical compensation layer) and the third retardation film (third optical compensation layer) were respectively changed to the manufacturing example shown in Table 2 An image display device was produced in the same manner as in Example 1 except for the retardation film. Then, the image display device was subjected to the above-mentioned reflection brightness measurement.

Table 2 No. Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 first optical compensation layer (First retardation film) Manufacturing example Manufacturing example 20 Manufacturing example 21 Manufacturing example 23 Manufacturing example 20 Manufacturing example 19 Manufacturing example 36 Manufacturing example 31 refractive index properties nx>ny=nz nx＞ny＞nz nx>ny=nz Re ¹ (550)[nm] 100 190 40 100 120 100 100 Rth ¹ (550)[nm] 100 190 40 100 120 110 100 Nz coefficient 1.0 1.0 1.0 1.0 1.0 1.1 1.0 Re ¹ (450)/Re ¹ (550) 1.0 1.0 1.0 1.0 1.0 1.0 0.8 The angle between the absorption axis direction and the slow axis direction [°] 80 140 70 20 55 80 80 second optical compensation layer (Second retardation film) Manufacturing example Manufacturing example 5 Manufacturing example 6 Manufacturing example 4 Manufacturing example 7 Manufacturing example 8 Manufacturing example 5 Manufacturing example 5 refractive index properties nz>nx=ny Re ² (550)[nm] 0 0 0 0 0 0 0 Rth ² (550)[nm] -130 -110 -90 -70 -80 -130 -130 third optical compensation layer (Third phase difference film) Manufacturing example Manufacturing example 18 Manufacturing example 24 Manufacturing example 18 Manufacturing example 21 Manufacturing example 23 Manufacturing example 37 Manufacturing example 32 refractive index properties nx>ny=nz nx＞ny＞nz nx>ny=nz Re ³ (550)[nm] 110 50 110 190 40 110 110 Rth ³ (550)[nm] 110 50 110 190 40 121 110 Nz coefficient 1.0 1.0 1.0 1.0 1.0 1.1 1.0 Re ³ (450)/Re ³ (550) 1.0 1.0 1.0 1.0 1.0 1.0 0.8 The angle between the absorption axis direction and the slow axis direction [°] 40 60 45 145 25 40 40 (Rth ¹ - Re ¹ /2) + (Rth ² ) + (Rth ³ - Re ³ /2) -25 10 -15 75 0 -4 -25 Brightness (cd/m ² ) 0.10 0.50 0.45 0.80 0.45 0.25 0.08

[Examples 16-23] Except that the first retardation film (first optical compensation layer), the second retardation film (second optical compensation layer) and the third retardation film (third optical compensation layer) were respectively changed to the manufacturing example shown in Table 3 An image display device was produced in the same manner as in Example 1 except for the retardation film. Then, the image display device was subjected to the above-mentioned reflection brightness measurement.

table 3 No. Example 16 Example 17 Example 18 Example 19 Example 20 Example 21 Example 22 Example 23 first optical compensation layer (First retardation film) Manufacturing example Manufacturing example 25 Manufacturing example 21 Manufacturing example 22 Manufacturing example 18 Manufacturing example 26 Manufacturing example 27 Manufacturing example 38 Manufacturing example 33 refractive index properties nx>ny=nz nx＞ny＞nz nx>ny=nz Re ¹ (550)[nm] 180 190 70 110 170 160 190 190 Rth ¹ (550)[nm] 180 190 70 110 170 160 209 190 Nz coefficient 1.0 1.0 1.0 1.0 1.0 1.0 1.1 1.0 Re ¹ (450)/Re ¹ (550) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.8 The angle between the absorption axis direction and the slow axis direction[] 140 45 85 95 50 60 45 45 second optical compensation layer (Second retardation film) Manufacturing example Manufacturing example 1 Manufacturing example 1 Manufacturing example 2 Manufacturing example 2 Manufacturing example 1 Manufacturing example 8 Manufacturing example 1 Manufacturing example 1 refractive index properties nz>nx=ny Re ² (550)[nm] 0 0 0 0 0 0 0 0 Rth ² (550)[nm] -60 -60 -30 -30 -60 -80 -60 -60 third optical compensation layer (Third phase difference film) Manufacturing example Manufacturing example 13 Manufacturing example 16 Manufacturing example 17 Manufacturing example 18 Manufacturing example 13 Manufacturing example 16 Manufacturing example 17 Manufacturing example 16 refractive index properties nz=nx>ny nz＞nx＞ny nz=nx>ny Re ³ (550)[nm] 40 50 120 150 40 50 50 50 Rth ³ (550)[nm] 0 0 0 0 0 0 -15 0 Nz coefficient - - - - - - -0.3 - Re ³ (450)/Re ³ (550) 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 The angle between the absorption axis direction and the slow axis direction [°] 60 135 45 50 155 5 135 135 (Rth ¹ - Re ¹ /2) + (Rth ² ) + (Rth ³ - Re ³ /2) 10 10 -55 -50 5 -25 14 10 Brightness (cd/m ² ) 0.53 0.42 0.70 0.70 0.49 0.82 0.45 0.37

[Comparative Examples 1 and 2] Except that the first retardation film (first optical compensation layer) and the second retardation film (second optical compensation layer) are changed to the retardation films of the manufacturing examples shown in Table 4, and the third retardation film ( Except for the third optical compensation layer), an image display device was produced in the same manner as in Example 1. Then, the image display device was subjected to the above-mentioned reflection brightness measurement. [Comparative example 3] Except that the first retardation film (first optical compensation layer), the second retardation film (second optical compensation layer) and the third retardation film (third optical compensation layer) were respectively changed to the manufacturing examples shown in Table 4. An image display device was produced in the same manner as in Example 1 except for the retardation film. Then, the image display device was subjected to the above-mentioned reflection brightness measurement.

Table 4 No. Comparative example 1 Comparative example 2 Comparative example 3 first optical compensation layer (First retardation film) Manufacturing example Manufacturing example 34 Manufacturing example 28 Manufacturing example 28 refractive index properties nx>ny=nz Re ¹ (550)[nm] 140 270 270 Rth ¹ (550)[nm] 140 270 270 Nz coefficient 1.0 1.0 1.0 Re ¹ (450)/Re ¹ (550) 0.8 1.0 1.0 The angle between the absorption axis direction and the slow axis direction [°] 45 15 15 second optical compensation layer (Second retardation film) Manufacturing example Manufacturing example 9 Manufacturing example 29 Manufacturing example 29 refractive index properties nz>nx=ny nx>ny=nz Re ² (550)[nm] 0 135 135 Rth ² (550)[nm] -100 135 135 Nz coefficient - 1.0 1.0 Re ² (450)/Re ² (550) - 1.0 1.0 The angle between the absorption axis direction and the slow axis direction [°] - 75 75 third optical compensation layer (Third phase difference film) Manufacturing example - - Manufacturing example 10 refractive index properties - - nz>nx=ny Re ³ (550)[nm] - - 0 Rth ³ (550)[nm] - - -50 Nz coefficient - - - Re ³ (450)/Re ³ (550) - - - The angle between the absorption axis direction and the slow axis direction [°] - - - (Rth ¹ - Re ¹ /2) + (Rth ² - Re ² /2) + (Rth ³ - Re ³ /2) -30 203 153 Brightness [cd/m ² ] 1.00 1.80 1.20

[Evaluation] From Table 1 to Table 4, it can be seen that by making the refractive index characteristics of the second optical compensation layer show the relationship nz>nx=ny, the refractive index characteristics of the first optical compensation layer and/or the third optical compensation layer can be improved. Show the relationship of nx>ny≧nz, make Re ¹ (550) and Re ³ (550) respectively above 10 nm and below 220 nm, and make the first optical compensation layer, the second optical compensation layer and the third optical compensation layer By satisfying the above formula (1), an image display device (organic EL display device) with significantly small reflection brightness can be realized. [Industrial availability]

The optical laminate according to the embodiment of the present invention can be suitably applied to an image display device (typically a liquid crystal display device or an organic EL display device).

10: First optical compensation layer 20: Second optical compensation layer 30: The third optical compensation layer 40:Polarizing plate 41:Polarizing element 42:Protective layer 100: Optical laminated body

FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

10: First optical compensation layer

20: Second optical compensation layer

30: The third optical compensation layer

40:Polarizing plate

41:Polarizing element

42:Protective layer

100: Optical laminated body

Claims (21)

An optical laminate, which is provided in this order: a polarizing element; a first optical compensation layer whose refractive index characteristics show the relationship nx>ny; a second optical compensation layer whose refractive index characteristics show the relationship nz>nx=ny; and refractive index characteristics The third optical compensation layer showing the relationship nx>ny, the refractive index characteristics of the above-mentioned first optical compensation layer and/or the above-mentioned third optical compensation layer showing the relationship nx>ny≧nz, the in-plane of the above-mentioned first optical compensation layer The phase difference Re ¹ (550) and the in-plane phase difference Re ³ (550) of the above-mentioned third optical compensation layer are respectively above 10 nm and below 220 nm. The absorption axis direction of the above-mentioned polarizing element is slower than the direction of the above-mentioned first optical compensation layer. The axial directions intersect in a substantially non-orthogonal manner, and the first optical compensation layer, the second optical compensation layer and the third optical compensation layer satisfy the following formula (1): [Equation 1] (1) (In formula (1), Rth ¹ (550) represents the phase difference in the thickness direction of the first optical compensation layer; Rth ² (550) represents the phase difference in the thickness direction of the second optical compensation layer; Rth ³ (550 ) represents the phase difference in the thickness direction of the third optical compensation layer; Re ¹ (550) represents the in-plane phase difference of the first optical compensation layer; Re ³ (550) represents the in-plane phase difference of the third optical compensation layer). The optical laminated body of claim 1, wherein the refractive index characteristics of the first optical compensation layer show the relationship nz≧nx>ny, The refractive index characteristics of the above-mentioned third optical compensation layer show the relationship nx>ny≧nz. The optical laminated body of claim 2, wherein the in-plane phase difference Re ³ (550) of the third optical compensation layer is 80 nm or more and 180 nm or less. The optical laminated body of Claim 2, wherein the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 50 nm or more. The optical laminated body according to claim 4, wherein the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 110 nm or more. The optical laminated body according to claim 2, wherein the phase difference Rth ² (550) in the thickness direction of the second optical compensation layer is -80 nm or more. The optical laminated body of Claim 2, wherein the refractive index characteristics of the first optical compensation layer show the relationship nz=nx>ny, The refractive index characteristics of the above-mentioned third optical compensation layer show the relationship nx>ny=nz. The optical laminated body according to claim 1, wherein the refractive index characteristics of each of the first optical compensation layer and the third optical compensation layer show a relationship of nx>ny≧nz. The optical laminated body of claim 8, wherein the in-plane phase difference Re ³ (550) of the third optical compensation layer is 50 nm or more and 180 nm or less. The optical laminated body according to claim 8, wherein the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 50 nm or more and 180 nm or less. The optical laminate according to claim 8, wherein the retardation Rth ² (550) in the thickness direction of the second optical compensation layer is -120 nm or less. The optical laminated body according to claim 8, wherein the refractive index characteristics of each of the first optical compensation layer and the third optical compensation layer show a relationship of nx>ny=nz. The optical laminated body of claim 1, wherein the refractive index characteristics of the first optical compensation layer show a relationship of nx>ny≧nz, The refractive index characteristics of the above-mentioned third optical compensation layer show the relationship nz≧nx>ny. The optical laminate according to claim 13, wherein the retardation Rth ² (550) in the thickness direction of the second optical compensation layer is -70 nm or more. The optical laminated body of claim 13, wherein the in-plane phase difference Re ³ (550) of the third optical compensation layer is 140 nm or less. The optical laminated body of claim 13, wherein the in-plane phase difference Re ³ (550) of the third optical compensation layer is 45 nm or more. The optical laminated body of claim 13, wherein the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 80 nm or more. The optical laminated body of claim 17, wherein the in-plane phase difference Re ¹ (550) of the first optical compensation layer is 180 nm or more. The optical laminated body of claim 13, wherein the refractive index characteristics of the first optical compensation layer show a relationship of nx>ny=nz, The refractive index characteristics of the above-mentioned third optical compensation layer show the relationship nz=nx>ny. The optical laminate according to claim 1, wherein the refractive index characteristics of the first optical compensation layer and the third optical compensation layer show a relationship of nx>ny≧nz, Re(450)/Re(550) of the optical compensation layer Less than 1. An image display device having: image display unit, and The optical laminate according to any one of claims 1 to 20.