JP2023111231A - Optical laminate and image display device - Google Patents

Abstract

To provide an optical laminate which may realize an image display device capable of reducing reflection brightness.SOLUTION: An optical laminate according to an embodiment of the present invention comprises a polarizer, a first optical compensation layer having a refractive index property exhibiting a relationship expressed as nz≥nx>ny, a second optical compensation layer having a refractive index property exhibiting a relationship expressed as nx>ny, and a third optical compensation layer having a refractive index property exhibiting a relationship expressed as nx>ny, arranged in the described order. The reflective property of the second optical compensation layer and/or that of the third optical compensation layer exhibit a relationship expressed as nx>ny≥nz. Every optical compensation layer has an in-plane retardation in a range of 10-220 nm, inclusive. An absorption axis direction of the polarizer and a slow axis direction of the first optical compensation layer intersect without being substantially orthogonal. The first, second, and third optical compensation layers satisfy a specific expression (1).SELECTED DRAWING: Figure 1

Description

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

2. Description of the Related Art Image display devices generally use various optical laminates in which a polarizer and an optical compensation film are combined in order to compensate for optical properties suitable for the application. As such an optical laminate, for example, a polarizer, a first birefringent layer that is a λ/2 plate, a second birefringent layer that is a λ/4 plate, and a refractive index characteristic of nz>nx= An elliptically polarizing plate having a third birefringent layer showing the relationship of ny in this order has been proposed (see Patent Document 1, for example).
Further, in the image display device, there may be problems such as the reflection of external light and reflection of the background due to the display device itself or a reflector (for example, a touch panel portion, metal wiring) used in the display device. In particular, since an organic EL panel has a highly reflective metal layer, problems such as external light reflection and background reflection are likely to occur. Therefore, it has been studied to arrange an optical layered body on the viewing side of the image display panel to reduce the reflection luminance 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 luminance, and there is room for improvement in reducing the reflection luminance.

JP 2006-268007 A

The present invention has been made to solve the above-described conventional problems, and a main object of the present invention is to provide an optical layered body capable of realizing an image display device capable of reducing reflection luminance.

（式（１）中、Ｒｔｈ^１（５５０）は、第１光学補償層の厚み方向の位相差を表し；Ｒｔｈ^２（５５０）は、第２光学補償層の厚み方向の位相差を表し；Ｒｔｈ^３（５５０）は、第３光学補償層の厚み方向の位相差を表し；Ｒｅ^１（５５０）は、第１光学補償層の面内位相差を表し；Ｒｅ^２（５５０）は、第２光学補償層の面内位相差を表し；Ｒｅ^３（５５０）は、第３光学補償層の面内位相差を表す）。
１つの実施形態においては、上記第２光学補償層および上記第３光学補償層のそれぞれの屈折率特性が、ｎｘ＞ｎｙ≧ｎｚの関係を示す。
１つの実施形態において、上記第２光学補償層の面内位相差Ｒｅ^２（５５０）は、１８０ｎｍ以下である。
１つの実施形態において、上記第１光学補償層の面内位相差Ｒｅ^１（５５０）は、５０ｎｍ以上１８０ｎｍ以下である。
１つの実施形態において、上記第１光学補償層の面内位相差Ｒｅ^１（５５０）は、１００ｎｍ以下である。
１つの実施形態において、上記第３光学補償層の面内位相差Ｒｅ^３（５５０）は、１８０ｎｍ以下である。
１つの実施形態においては、上記第１光学補償層の屈折率特性は、ｎｚ＝ｎｘ＞ｎｙの関係を示し、上記第２光学補償層および上記第３光学補償層のそれぞれの屈折率特性は、ｎｘ＞ｎｙ＝ｎｚの関係を示す。
１つの実施形態においては、上記第２光学補償層の屈折率特性は、ｎｘ＞ｎｙ≧ｎｚの関係を示し、上記第３光学補償層の屈折率特性は、ｎｚ≧ｎｘ＞ｎｙの関係を示す。
１つの実施形態において、上記第２光学補償層の面内位相差Ｒｅ^２（５５０）は、５０ｎｍ以上１８０ｎｍ以下である。
１つの実施形態において、上記第２光学補償層の面内位相差Ｒｅ^２（５５０）は、１００ｎｍ以上である。
１つの実施形態において、上記第３光学補償層の面内位相差Ｒｅ^３（５５０）は、６０ｎｍ以上１８０ｎｍ以下である。
１つの実施形態において、上記第１光学補償層の面内位相差Ｒｅ^１（５５０）は、１２０ｎｍ以下である。
１つの実施形態においては、上記第１光学補償層および上記第３光学補償層のそれぞれの屈折率特性は、ｎｚ＝ｎｘ＞ｎｙの関係を示し、上記第２光学補償層の屈折率特性は、ｎｘ＞ｎｙ＝ｎｚの関係を示す。
１つの実施形態においては、上記第２光学補償層の屈折率特性は、ｎｚ≧ｎｘ＞ｎｙの関係を示し、上記第３光学補償層の屈折率特性は、ｎｘ＞ｎｙ≧ｎｚの関係を示す。
１つの実施形態において、上記第２光学補償層の面内位相差Ｒｅ^２（５５０）は、５０ｎｍ以上１８０ｎｍ以下である。
１つの実施形態において、上記第３光学補償層の面内位相差Ｒｅ^３（５５０）は、５０ｎｍ以上である。
１つの実施形態において、上記第３光学補償層の面内位相差Ｒｅ^３（５５０）は、９０ｎｍ以上である。
１つの実施形態において、上記第３光学補償層の面内位相差Ｒｅ^３（５５０）は、１８０ｎｍ以下である。
１つの実施形態において、上記第１光学補償層の面内位相差Ｒｅ^１（５５０）は、５０ｎｍ以上１８０ｎｍ以下である。
１つの実施形態においては、上記第１光学補償層および上記第２光学補償層のそれぞれの屈折率特性は、ｎｚ＝ｎｘ＞ｎｙの関係を示し、上記第３光学補償層の屈折率特性は、ｎｘ＞ｎｙ＝ｎｚの関係を示す。
１つの実施形態においては、上記第２光学補償層および上記第３光学補償層のうち、屈折率特性がｎｘ＞ｎｙ≧ｎｚの関係を示す光学補償層のＲｅ（４５０）／Ｒｅ（５５０）は１未満である。
本発明の別の局面による画像表示装置は、画像表示セルと；上記光学積層体と；を備える。 An optical laminate according to an embodiment of the present invention comprises a polarizer; a first optical compensation layer having a refractive index characteristic of nz≧nx>ny; and a second optical compensation layer having a refractive index characteristic of nx>ny. and a third optical compensation layer whose refractive index characteristics exhibit a relationship of nx>ny; are provided in this order. The refractive index characteristics of the second optical compensation layer and/or the third optical compensation layer exhibit a relationship of nx>ny≧nz. In-plane retardation Re ¹ (550) of the first optical compensation layer, in-plane retardation Re ² (550) of the second optical compensation layer, and in-plane retardation Re ³ (550) of the third optical compensation layer is 10 nm or more and 220 nm or less. The absorption axis direction of the polarizer and the slow axis direction of the first optical compensation layer cross each other without being substantially orthogonal. The first optical compensation layer, the second optical compensation layer and the third optical compensation layer satisfy the following formula (1).

(In formula (1), Rth ¹ (550) represents the retardation in the thickness direction of the first optical compensation layer; Rth ² (550) represents the retardation in the thickness direction of the second optical compensation layer; Rth ³ (550) represents the retardation in the thickness direction of the third optical compensation layer; Re ¹ (550) represents the in-plane retardation of the first optical compensation layer; Re ² (550) represents the second optical represents the in-plane retardation of the compensation layer; Re ³ (550) represents the in-plane retardation of the third optical compensation layer).
In one embodiment, the refractive index characteristics of the second optical compensation layer and the third optical compensation layer exhibit a relationship of nx>ny≧nz.
In one embodiment, the in-plane retardation Re ² (550) of the second optical compensation layer is 180 nm or less.
In one embodiment, the in-plane retardation Re ¹ (550) of the first optical compensation layer is 50 nm or more and 180 nm or less.
In one embodiment, the in-plane retardation Re ¹ (550) of the first optical compensation layer is 100 nm or less.
In one embodiment, the in-plane retardation Re ³ (550) of the third optical compensation layer is 180 nm or less.
In one embodiment, the refractive index characteristics of the first optical compensation layer exhibit a relationship of nz=nx>ny, and the refractive index characteristics of each of the second optical compensation layer and the third optical compensation layer are: A relationship of nx>ny=nz is shown.
In one embodiment, the refractive index characteristics of the second 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 in-plane retardation Re ² (550) of the second optical compensation layer is 50 nm or more and 180 nm or less.
In one embodiment, the in-plane retardation Re ² (550) of the second optical compensation layer is 100 nm or more.
In one embodiment, the in-plane retardation Re ³ (550) of the third optical compensation layer is 60 nm or more and 180 nm or less.
In one embodiment, the in-plane retardation Re ¹ (550) of the first 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 exhibit a relationship of nz=nx>ny, and the refractive index characteristics of the second optical compensation layer are: A relationship of nx>ny=nz is shown.
In one embodiment, the refractive index characteristics of the second optical compensation layer exhibit a relationship of nz≧nx>ny, and the refractive index characteristics of the third optical compensation layer exhibit a relationship of nx>ny≧nz. .
In one embodiment, the in-plane retardation Re ² (550) of the second optical compensation layer is 50 nm or more and 180 nm or less.
In one embodiment, the in-plane retardation Re ³ (550) of the third optical compensation layer is 50 nm or more.
In one embodiment, the in-plane retardation Re ³ (550) of the third optical compensation layer is 90 nm or more.
In one embodiment, the in-plane retardation Re ³ (550) of the third optical compensation layer is 180 nm or less.
In one embodiment, the in-plane retardation Re ¹ (550) of the first optical compensation layer is 50 nm or more and 180 nm or less.
In one embodiment, the refractive index characteristics of each of the first optical compensation layer and the second optical compensation layer exhibit a relationship of nz=nx>ny, and the refractive index characteristics of the third optical compensation layer are: A relationship of nx>ny=nz is shown.
In one embodiment, of the second optical compensation layer and the third optical compensation layer, Re(450)/Re(550) of the optical compensation layer whose refractive index characteristics exhibit a relationship of nx>ny≧nz is less than one.
An image display device according to another aspect of the present invention includes: an image display cell; and the optical laminate.

According to the optical layered body according to the embodiment of the present invention, it is possible to realize an image display device capable of reducing reflection luminance.

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

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

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the in-plane direction orthogonal to the slow axis (i.e., fast axis direction) and "nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re(λ)” is an in-plane retardation measured at 23° C. with light having a wavelength of λ nm. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film). In this specification, the "in-plane retardation Re (λ) of the first optical compensation layer" is referred to as "Re ¹ (λ)", and the "in-plane retardation Re (λ) of the second optical compensation layer" is sometimes referred to as "Re ² (λ)", and "the in-plane retardation Re (λ) of the third optical compensation layer" is sometimes referred to as "Re ³ (λ)".
(3) Thickness direction retardation (Rth)
“Rth(λ)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of λ nm. For example, “Rth(550)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of 550 nm. Rth(λ) is determined by the formula: Rth(λ)=(nx−nz)×d, where d (nm) is the thickness of the layer (film). In this specification, the “thickness direction retardation Rth (λ) of the first optical compensation layer” is referred to as “Rth ¹ (λ)”, and the “in-plane retardation Re (λ) of the second optical compensation layer ” may be referred to as “Rth ² (λ)”, and “the in-plane retardation Re(λ) of the third optical compensation layer” may be referred to as “Rth ³ (λ)”.
(4) Nz Coefficient The Nz coefficient is obtained by Nz=Rth/Re.
(5) Substantially parallel or orthogonal The expressions “substantially orthogonal” and “substantially orthogonal” include cases where the angle formed by two directions is 90°±3°, and “substantially parallel” and “substantially orthogonal” The expression "substantially parallel" includes the case where the angle formed by the two directions is 0°±3°. Moreover, the phrase "intersect without being substantially orthogonal" means that the angle formed by the two directions is neither substantially orthogonal nor substantially parallel. More specifically, the expression "intersect without being substantially orthogonal" means that the angle formed by the two directions exceeds 3 ° and is less than 87 °, and exceeds 93 ° and 177 ° It includes cases where it is less than, preferably 5° or more and 85° or less, or 95° or more and 175° or less.

（式（１）中、Ｒｔｈ^１（５５０）は、第１光学補償層の厚み方向の位相差を表し；Ｒｔｈ^２（５５０）は、第２光学補償層の厚み方向の位相差を表し；Ｒｔｈ^３（５５０）は、第３光学補償層の厚み方向の位相差を表し；Ｒｅ^１（５５０）は、第１光学補償層の面内位相差を表し；Ｒｅ^２（５５０）は、第２光学補償層の面内位相差を表し；Ｒｅ^３（５５０）は、第３光学補償層の面内位相差を表す）。
このような構成を有する光学積層体を画像表示装置に適用すると、画像表示装置の反射輝度の低減を図ることができる。
なお、光学積層体が、面内位相差Ｒｅが２２０ｎｍを超過する光学補償層（とりわけλ／２板）を備える場合、当該光学補償層の薄厚化を図ることは困難であり、材料使用量の低減も困難である。さらに、面内位相差Ｒｅが２２０ｎｍを超過する光学補償層（とりわけλ／２板）では、配向角がばらつくおそれがあり、偏光子の吸収軸方向と当該光学補償層の遅相軸方向との軸ずれが大きくなり得る。また、同程度の軸ずれであっても位相差値が大きいほど光学補償への影響は大きくなる。そのため、このような光学補償層（λ／２板）を備える光学積層体では、本発明の実施形態による上記光学積層体のように、薄厚化を図り、かつ、画像表示装置の反射輝度の低減を図ることは困難である。 A. 1. Overall Configuration of Optical Layered Body FIG. 1 is a schematic cross-sectional view of an optical layered body according to one embodiment of the present invention. The optical layered body 100 of the illustrated example includes a polarizing plate 40 including a polarizer 41; and a third optical compensation layer 30 whose refractive index characteristics exhibit a relationship of nx>ny; are provided in this order. The refractive index characteristics of the second optical compensation layer 20 and/or the third optical compensation layer 30 exhibit a relationship of nx>ny≧nz. In-plane retardation Re ¹ (550) of the first optical compensation layer 10, in-plane retardation Re ² (550) of the second optical compensation layer 20, and in-plane retardation Re ³ (550) of the third optical compensation layer 30 is 10 nm or more and 220 nm or less, preferably 30 nm or more and 200 nm or less. The absorption axis direction of the polarizer 41 and the slow axis direction of the first optical compensation layer 10 cross each other without being substantially orthogonal. The first optical compensation layer 10, the second optical compensation layer 20 and the third optical compensation layer 30 satisfy the following formula (1).

(In formula (1), Rth ¹ (550) represents the retardation in the thickness direction of the first optical compensation layer; Rth ² (550) represents the retardation in the thickness direction of the second optical compensation layer; Rth ³ (550) represents the retardation in the thickness direction of the third optical compensation layer; Re ¹ (550) represents the in-plane retardation of the first optical compensation layer; Re ² (550) represents the second optical represents the in-plane retardation of the compensation layer; Re ³ (550) represents the in-plane retardation of the third optical compensation layer).
When the optical layered body having such a structure is applied to an image display device, it is possible to reduce the reflection brightness of the image display device.
In addition, when the optical laminate includes an optical compensation layer (especially a λ/2 plate) having an in-plane retardation Re exceeding 220 nm, it is difficult to reduce the thickness of the optical compensation layer, and the amount of material used is reduced. Reduction is also difficult. Furthermore, in an optical compensation layer (especially a λ/2 plate) having an in-plane retardation Re exceeding 220 nm, the orientation angle may vary, and the absorption axis direction of the polarizer and the slow axis direction of the optical compensation layer may vary. Axial misalignment can be large. Further, even if the axial misalignment is of the same degree, the larger the phase difference value, the greater the influence on the optical compensation. Therefore, in the optical layered body including such an optical compensation layer (λ/2 plate), the thickness is reduced and the reflection brightness of the image display device is reduced like the optical layered body according to the embodiment of the present invention. it is difficult to

The value calculated in the above formula (1) is, for example, -200 or more, preferably -150 or more, and for example, 150 or less, preferably 100 or less.
The refractive index characteristics of the first optical compensation layer 10 exhibit a relationship of nz=nx>ny or exhibit a relationship of nz>nx>ny. Here, "nz=nx" includes not only the case where nz and nx are completely the same, but also the case where nz and nx are substantially the same.

The refractive index characteristics of at least one of the second optical compensation layer 20 and the third optical compensation layer 30 exhibit a relationship of nx>ny≧nz. When the refractive index characteristics of the third optical compensation layer 30 show the relationship of nx>ny≧nz, the refractive index characteristics of the second optical compensation layer 20 typically show the relationship of nx>ny≧nz, Alternatively, it shows the relationship of nz≧nx>ny. Further, when the refractive index characteristics of the second optical compensation layer 20 show the relationship of nx>ny≧nz, the refractive index characteristics of the third optical compensation layer 30 typically show the relationship of nx>ny≧nz. or nz≧nx>ny. Here, "ny=nz" includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

Among the first optical compensation layer 10, the second optical compensation layer 20, and the third optical compensation layer 30, the thickness direction retardation Rth (550) of the optical compensation layer whose refractive index characteristics exhibit the relationship of nz=nx>ny is , for example, from -3.0 nm to 3.0 nm, preferably 0 nm.
Among the first optical compensation layer 10, the second optical compensation layer 20, and the third optical compensation layer 30, the thickness direction retardation Rth (550) of the optical compensation layer whose refractive index characteristics exhibit the relationship of 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. In this case, 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.
Among the second optical compensation layer 20 and the third optical compensation layer 30, the thickness direction retardation Rth (550) of the optical compensation layer exhibiting the relationship of nx>ny≧nz in refractive index characteristics is, for example, 10 nm or more and 220 nm or less, It is preferably 30 nm or more and 200 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, of the second optical compensation layer 20 and the third optical compensation layer 30, Re(450)/Re(550) of the optical compensation layer whose refractive index characteristic exhibits a relationship of nx>ny≧nz is It is less than 1 and typically greater than or equal to 0.8.

In one embodiment, the absorption axis direction of the polarizer 41 and the slow axis direction of the second optical compensation layer 20 intersect without being substantially orthogonal, and the absorption axis direction of the polarizer 41 and the third It intersects with the slow axis direction of the optical compensation layer 30 without being substantially orthogonal.

The optical layered body may be in the shape of a sheet or in the shape of a long sheet. As used herein, the term "long shape" means an elongated shape whose length is sufficiently long relative to its width, for example, an elongated shape whose length is 10 times or more, preferably 20 times or more, its width. include. The long optical layered body can be wound into a roll.

Practically, 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 layered body can be attached to the image display cell. Furthermore, it is preferable that a release liner is temporarily attached to the surface of the pressure-sensitive adhesive layer until the optical layered body is used. Temporarily attaching the release liner protects the pressure-sensitive adhesive layer and enables roll formation.

Specific combinations of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer in the optical laminate will be described below.

A-1. First Optical Laminate In one embodiment, the first optical compensation layer 10 exhibits a relationship of nz≧nx>ny, and the refractive index characteristics of each of the second optical compensation layer 20 and the third optical compensation layer 30 are nx >ny≧nz. An optical layered body including such a combination of the first optical compensation layer, the second optical compensation layer and the third optical compensation layer may be referred to as a first optical layered body.
In the first optical laminate, more preferably, the refractive index characteristics of the first optical compensation layer 10 exhibit a relationship of nz=nx>ny, and the refractive index characteristics of the second optical compensation layer 20 and the third optical compensation layer 30 The rate characteristics show the relationship nx>ny=nz. Such a combination of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer can further reduce the reflection brightness of the image display device.

In the first optical laminate, the in-plane retardation Re ¹ (550) of the first optical compensation layer 10 is preferably 40 nm or more, more preferably 50 nm or more, preferably 200 nm or less, more preferably 180 nm or less, More preferably, it is 100 nm or less.
In the first optical laminate, when Re ¹ (550) is within the above range, the reflection luminance can be further reduced in the image display device.
In the first optical laminate, the angle between the absorption axis direction of the polarizer 41 and the slow axis direction of the first optical compensation layer 10 is preferably 5° or more and 80° or less, or 140° or more and 175°. ° or less, more preferably 5° or more and 60° or less, and still more preferably 5° or more and 20° or less.

In the first optical laminate, the in-plane retardation Re ² (550) of the second optical compensation layer 20 is preferably 40 nm or more, more preferably 50 nm or more, preferably 200 nm or less, more preferably 180 nm or less, More preferably, it is 100 nm or less.
In the first optical laminate, the thickness direction retardation Rth ² (550) of the second optical compensation layer 20 is preferably 40 nm or more, more preferably 50 nm or more, and preferably 200 nm or less, more preferably 180 nm or less. , and more preferably 100 nm or less.
In the first optical layered body, when Re ² (550) and/or Rth ² (550) are within the above ranges, the reflection luminance can be further reduced in the image display device.
In the first optical laminate, the angle between the absorption axis direction of the polarizer 41 and the slow axis direction of the second optical compensation layer 20 is preferably 20° or more and 80° or less, or 100° or more and 170°. ° or less, more preferably 30° or more and 70° or less, still more preferably 40° or more and 60° or less.

In the first optical laminate, the in-plane retardation Re ³ (550) of the third optical compensation layer 30 is preferably 35 nm or more, preferably 200 nm or less, more preferably 180 nm or less, still more preferably 100 nm or less, Especially preferably, it is 70 nm or less.
In the first optical laminate, the thickness direction retardation Rth ³ (550) of the third optical compensation layer 10 is preferably 35 nm or more, preferably 200 nm or less, more preferably 180 nm or less, and still more preferably 100 nm or less. , particularly preferably 70 nm or less.
In the first optical laminate, when Re ³ (550) and/or Rth ³ (550) are within the above ranges, the reflection luminance can be further reduced in the image display device.
In the first optical laminate, the angle between the absorption axis direction of the polarizer 41 and the slow axis direction of the third optical compensation layer 30 is preferably 20° or more and 80° or less, more preferably 30°. ° or more and 70° or less, more preferably 40° or more and 60° or less.

A-2. Second Optical Laminate In one embodiment, the refractive index characteristics of each of the first optical compensation layer 10 and the third optical compensation layer 30 exhibit a relationship of nz≧nx>ny, and the refractive index characteristics of the second optical compensation layer 20 The rate characteristics show a relationship of nx>ny≧nz. An optical layered body including such a combination of the first optical compensation layer, the second optical compensation layer and the third optical compensation layer may be referred to as a second optical layered body.
In the second optical laminate, more preferably, the refractive index characteristics of each of the first optical compensation layer 10 and the third optical compensation layer 30 exhibit a relationship of nz=nx>ny, and the refractive index of the second optical compensation layer 20 The rate characteristic shows the relationship of nx>ny=nz. Such a combination of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer can further reduce the reflection brightness of the image display device.

In the second optical laminate, the in-plane retardation Re ¹ (550) of the first optical compensation layer 10 is preferably 35 nm or more, preferably 200 nm or less, more preferably 120 nm or less, and still more preferably 70 nm or less. be.
In the second optical laminate, when Re ¹ (550) is within the above range, the reflection luminance can be further reduced in the image display device.
In the second optical laminate, the angle formed by the absorption axis direction of the polarizer 41 and the slow axis direction of the first optical compensation layer 10 is preferably 5° or more and 80° or less, or 95° or more and 170°. ° or less, more preferably 130° or more and 170° or less, still more preferably 140° or more and 170° or less.

In the second optical laminate, the in-plane retardation Re ² (550) of the second optical compensation layer 20 is preferably 40 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, and particularly preferably 140 nm or more. , preferably 200 nm or less, more preferably 180 nm or less.
In the second optical laminate, the thickness direction retardation Rth ² (550) of the second optical compensation layer 20 is preferably 40 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, and particularly preferably 140 nm or more. It is preferably 200 nm or less, more preferably 180 nm or less.
In the second optical layered body, when Re ² (550) and/or Rth ² (550) are within the above ranges, the reflection luminance can be further reduced in the image display device.
In the second optical laminate, the angle between the absorption axis direction of the polarizer 41 and the slow axis direction of the second optical compensation layer 20 is preferably 5° or more and 80° or less, or 100° or more and 160° or more. ° or less, more preferably 5° or more and 60° or less, still more preferably 10° or more and 30° or less.

In the second optical laminate, the in-plane retardation Re ³ (550) of the third optical compensation layer 30 is preferably 40 nm or more, more preferably 50 nm or more, still more preferably 60 nm or more, and preferably 200 nm or less. It is more preferably 180 nm or less, still more preferably 100 nm or less.
In the second optical laminate, when Re ³ (550) is within the above range, the reflection luminance can be further reduced in the image display device.
In the second optical laminate, the angle between the absorption axis direction of the polarizer 41 and the slow axis direction of the third optical compensation layer 30 is preferably 10° or more and 85° or less, or 110° or more and 160° or more. ° or less, more preferably 30° or more and 85° or less, still more preferably 50° or more and 70° or less.

A-3. Third Optical Laminate In one embodiment, the refractive index characteristics of each of the first optical compensation layer 10 and the second optical compensation layer 20 exhibit a relationship of nz≧nx>ny, and the refractive index of the third optical compensation layer 30 The rate characteristics show a relationship of nx>ny≧nz. An optical layered body including such a combination of the first optical compensation layer, the second optical compensation layer and the third optical compensation layer may be referred to as a third optical layered body.
In the third optical laminate, more preferably, the refractive index characteristics of each of the first optical compensation layer 10 and the second optical compensation layer 20 exhibit a relationship of nz=nx>ny, and the refractive index of the third optical compensation layer 30 The rate characteristic shows the relationship of nx>ny=nz. Such a combination of the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer can further reduce the reflection brightness of the image display device.

In the third optical laminate, the in-plane retardation Re ¹ (550) of the first optical compensation layer 10 is preferably 40 nm or more, more preferably 50 nm or more, still more preferably 80 nm or more, and preferably 200 nm or less. It is more preferably 180 nm or less, still more preferably 150 nm or less.
In the third optical layered body, when Re ¹ (550) is equal to or higher than the above lower limit, the reflection luminance can be further reduced in the image display device.
In the third optical laminate, the angle formed by the absorption axis direction of the polarizer 41 and the slow axis direction of the first optical compensation layer 10 is preferably 10° or more and 85° or less, or 95° or more and 160°. ° or less, more preferably 95° or more and 140° or less, still more preferably 95° or more and 120° or less.

In the third optical laminate, the in-plane retardation Re ² (550) of the second optical compensation layer 20 is preferably 40 nm or more, more preferably 50 nm or more, still more preferably 70 nm or more, and preferably 200 nm or less. It is more preferably 180 nm or less, still more preferably 120 nm or less.
In the third optical layered body, when Re ² (550) is within the above range, the reflection luminance can be further reduced in the image display device.
In the third optical laminate, the angle formed by the absorption axis direction of the polarizer 41 and the slow axis direction of the second optical compensation layer 20 is preferably 5° or more and 80° or less, or 110° or more and 175°. ° or less, more preferably 5° or more and 60° or less, and still more preferably 5° or more and 20° or less.

In the third optical laminate, the in-plane retardation Re ³ (550) of the third optical compensation layer 30 is preferably 40 nm or more, more preferably 50 nm or more, still more preferably 90 nm or more, and preferably 200 nm or less. It is more preferably 180 nm or less, still more preferably 160 nm or less.
In the third optical laminate, the thickness direction retardation Rth ³ (550) of the third optical compensation layer 30 is preferably 40 nm or more, more preferably 50 nm or more, still more preferably 90 nm or more, and preferably 200 nm or less. , more preferably 180 nm or less, and still more preferably 160 nm or less.
In the third optical layered body, when Re ³ (550) and/or Rth ³ (550) are within the above range, the reflection luminance can be further reduced in the image display device.
In the third optical laminate, the angle formed by the absorption axis direction of the polarizer 41 and the slow axis direction of the third optical compensation layer 30 is preferably 10° or more and 70° or less, or 100° or more and 170° or more. ° or less, more preferably 110° or more and 160° or less, still more preferably 120° or more and 150° or less.

Each member constituting the optical laminate will be described below.

B. Polarizing plate B-1. Polarizer Any appropriate polarizer can be employed as the polarizer 41 . For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films. In addition, polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with dichroic substances such as iodine and dichroic dyes, and dehydrated PVA and dehydrochlorinated polyvinyl chloride films. A polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is preferably used because of its excellent optical properties.

The dyeing with iodine is performed by, for example, immersing the PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 times or more and 7 times or less. Stretching may be performed after the dyeing treatment, or may be performed while dyeing. Moreover, you may dye after extending|stretching. If necessary, the PVA-based film is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be washed away, but also the PVA-based film can be swollen to remove uneven dyeing. can be prevented.

Specific examples of the polarizer obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and the resin A polarizer obtained by using a laminate with a PVA-based resin layer formed by coating on a substrate can be mentioned. A polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material is obtained, for example, by applying a PVA-based resin solution to the resin base material and drying the resin base material. forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In one embodiment of the present invention, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may further include stretching the laminate in air at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. In addition, in one embodiment of the present invention, preferably, the laminate is subjected to dry shrinkage treatment to shrink the laminate by 2% or more in the width direction by heating while conveying in the longitudinal direction. Typically, the manufacturing method of the present embodiment includes subjecting the laminate to an in-air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing auxiliary stretching, it is possible to improve the crystallinity of PVA and achieve high optical properties even when PVA is coated on a thermoplastic resin. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process, resulting in high optical properties. can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance of the orientation of the polyvinyl alcohol molecules and deterioration of the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical properties of the polarizer obtained through treatment steps such as dyeing treatment and underwater stretching treatment in which the laminate is immersed in a liquid. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate. Then, any suitable protective layer may be laminated on the release surface according to the purpose. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. These publications are incorporated herein by reference in their entirety.

The thickness of the polarizer 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, even more preferably 3 μm or more and 12 μm or less, and particularly preferably 3 μm or more and 8 μm or less. If the thickness of the polarizer is within such a range, it is possible to satisfactorily suppress curling during heating, and obtain excellent durability in appearance during heating.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer 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 degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, still more preferably 99.9% or higher.

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

The protective layer is formed of any suitable film that can be used as a protective layer for polarizers. Specific examples of materials that are the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, and polysulfones. , polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based transparent resins. Thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may also be used. In addition, for example, a glassy polymer such as a siloxane-based polymer can also be used. Further, polymer films described in JP-A-2001-343529 (WO01/37007) can also be used.

When the polarizing plate 40 is provided with a protective layer located on the outermost surface of the image display device described later, the protective layer may be subjected to surface treatment such as hard coat treatment, antireflection treatment, anti-sticking treatment, anti-glare treatment, etc., as necessary. It may be treated.

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, still more preferably 5 μm or more and 150 μm or less. In addition, when the surface treatment is performed, the thickness of the protective layer is the thickness including the thickness of the surface treatment layer.

C. First Optical Compensation Layer In the illustrated example, the first optical compensation layer 10 is arranged adjacent to the polarizing plate 40 . More specifically, the first optical compensation layer 10 is arranged adjacent to the polarizer 41 . As used herein, “adjacently arranged” means being directly laminated or laminated only via an adhesive layer (for example, an adhesive layer or a pressure-sensitive adhesive layer). 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 light transmittance of the first optical compensation layer 10 at a wavelength of 550 nm is preferably 80% or higher, more preferably 85% or higher, and even more preferably 90% or higher. The theoretical upper limit of light transmittance is 100%, but surface reflection occurs due to the difference in refractive index between air and the retardation film, so the achievable upper limit of light transmittance is approximately 94%. .
The thickness of the first optical compensation layer 10 can be set so as to obtain desired optical properties. The thickness of the first optical compensation layer 10 is typically 1 μm or more, preferably 4 μm or more, and typically 40 μm or less, preferably 30 μm or less.

The refractive index characteristics of the first optical compensation layer 10 exhibit the relationship of nz≧nx>ny as described above. A layer (film) exhibiting refractive index characteristics of nz=nx>ny may be referred to as a “negative A plate” or the like. A layer (film) exhibiting refractive index characteristics of nz>nx>ny may be referred to as a “positive B plate” or the like.

The first optical compensation layer 10 is typically composed of a stretched polymer film containing a thermoplastic resin as a main component. A polymer exhibiting negative birefringence is preferably used as the thermoplastic resin. A retardation film having a refractive index ellipsoid satisfying nz≧nx>ny can be easily obtained by using a polymer exhibiting negative birefringence. Here, the term "exhibiting negative birefringence" means that when a polymer is oriented by stretching or the like, the refractive index in the stretching direction becomes relatively small. In other words, it means that the refractive index in the direction perpendicular to the stretching direction increases. Polymers exhibiting negative birefringence include, for example, polymers in which chemical bonds or functional groups with large polarization anisotropy such as aromatic rings and carbonyl groups are introduced into side chains. Specific examples include acrylic resins, styrene resins, maleimide resins, and the like.

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

The styrenic resin can be obtained, for example, by addition polymerization of styrenic monomers. Styrenic monomers include, for example, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, 2,5-dichlorostyrene and pt-butylstyrene can be mentioned.

The maleimide-based resin can be obtained, for example, by addition polymerization of a maleimide-based monomer. Maleimide-based monomers include, for example, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N-(2-propylphenyl ) maleimide, N-(2-isopropylphenyl)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, N-(2,6-dichlorophenyl)maleimide, N-(2-bromophenyl)maleimide, N-(2,6 -dibromophenyl)maleimide, N-(2-biphenyl)maleimide, N-(2-cyanophenyl)maleimide.

In the above addition polymerization, the birefringence properties of the resulting resin can be controlled by substituting the side chains, maleimidation, grafting, or the like after the polymerization.

The polymer exhibiting negative birefringence may be copolymerized with another monomer. By copolymerizing other monomers, brittleness, moldability, and heat resistance can be improved. Examples of the other monomer include olefins such as ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, and 1-hexene; acrylonitrile; acrylic acid; (meth)acrylates such as methyl and methyl methacrylate; maleic anhydride; and vinyl esters such as vinyl acetate.

When the polymer exhibiting negative birefringence is a copolymer of the styrene-based monomer and the other monomer, the blending ratio of the styrene-based monomer is preferably 50 mol % to 80 mol %. When the polymer exhibiting negative birefringence is a copolymer of the maleimide-based monomer and the other monomer, the blending ratio of the maleimide-based monomer is preferably 2 mol % to 50 mol %. By blending in such a range, a polymer film having excellent toughness and moldability can be obtained.

The polymer exhibiting negative birefringence is preferably a styrene-maleic anhydride copolymer, a styrene-acrylonitrile copolymer, a styrene-(meth)acrylate copolymer, a styrene-maleimide copolymer, a vinyl ester- Maleimide copolymers, olefin-maleimide copolymers, and the like are used. These can be used alone or in combination of two or more. These polymers can exhibit high negative birefringence and excellent heat resistance. These polymers are available from Nova Chemical Japan and Arakawa Chemical Industries, Ltd., for example.

A polymer having a repeating unit represented by the following general formula (I) is also preferably used as the polymer exhibiting negative birefringence. Such a polymer can exhibit even higher negative birefringence and be excellent in heat resistance and mechanical strength. Such a polymer can be obtained, for example, by using an N-phenyl-substituted maleimide into which a phenyl group having a substituent at least at the ortho position is introduced as the N-substituent of the maleimide-based monomer as the starting material.

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

The polymer exhibiting negative birefringence is not limited to those described above, and for example, a cyclic olefin copolymer as disclosed in JP-A-2005-350544 can also be used. Furthermore, compositions containing polymers and inorganic fine particles, as disclosed in JP-A-2005-156862, JP-A-2005-227427, etc., can also be preferably used. As the polymer exhibiting negative birefringence, one type may be used alone, or two or more types may be mixed and used. Further, these can be modified by copolymerization, branching, cross-linking, molecular terminal modification (or capping), stereoregular modification, and the like.

Any appropriate molding method can be adopted as a method for molding such a polymer film. Molding conditions can be appropriately set according to the composition and type of resin to be used, the molding method, and the like.

A retardation film (stretched film) corresponding to the first optical compensation layer can be obtained by stretching the polymer film under any appropriate stretching conditions.
Specific examples of the stretching method include a vertical uniaxial stretching method, a horizontal uniaxial stretching method, a vertical and horizontal successive biaxial stretching method, and a vertical and horizontal simultaneous biaxial stretching method. Preferably, a longitudinal uniaxial stretching method, a longitudinal and transverse successive biaxial stretching method, and a longitudinal and transverse simultaneous biaxial stretching method are used. In the polymer exhibiting negative birefringence, the refractive index in the stretching direction is relatively small as described above. The refractive index in the direction orthogonal to the conveying direction is nx). In the case of the longitudinal and transverse sequential biaxial stretching method and the longitudinal and transverse simultaneous biaxial stretching method, both the transport direction and the width direction can be the slow axes depending on the ratio of longitudinal and transverse stretching ratios. Specifically, when the draw ratio in the longitudinal (conveyance) direction is relatively increased, the transverse (width) direction becomes the slow axis, and when the draw ratio in the transverse (width) direction is relatively increased, the longitudinal (conveyance) The direction is the slow axis.

In addition, Re ¹ (550) and Rth ¹ (550) of the first optical compensation layer can be adjusted within the ranges described above by adjusting the thickness (original thickness), stretching temperature and stretching ratio of the polymer film. can.
The thickness of the polymer film (original thickness) is typically 5 μm or more, preferably 10 μm or more, and typically 50 μm or less, preferably 40 μm or more.
The stretching temperature (the temperature in the stretching oven when stretching the polymer film) is preferably around the glass transition temperature (Tg) of the polymer film. Specifically, it is preferably (Tg-10)°C to (Tg+30)°C, more preferably Tg to (Tg+25)°C, and particularly preferably (Tg+5)°C to (Tg+20)°C. If the stretching temperature is too low, the retardation value and the direction of the slow axis may become non-uniform, and the polymer film may crystallize (white turbidity). On the other hand, if the stretching temperature is excessively high, the polymer film may be melted or the retardation may be insufficiently developed. The stretching temperature is typically 120° C. or higher and 170° C. or lower. The glass transition temperature can be determined by the DSC method according to JISK7121-1987.
The draw ratio can be set to any appropriate value depending on the composition of the polymer film, the type of volatile components, the residual amount of volatile components, the desired retardation value, and the like. It is preferably 1.1 times or more and 3.0 times or less. Further, the feeding speed during stretching is preferably 0.5 m/min to 20 m/min from the viewpoint of mechanical accuracy of the stretching apparatus, stability and the like.

A method for obtaining a retardation film using a polymer exhibiting negative birefringence has been described above, but a retardation film can also be obtained using a polymer exhibiting positive birefringence. As a method of obtaining a retardation film using a polymer exhibiting positive birefringence, for example, as disclosed in JP-A-2000-231016, JP-A-2000-206328, JP-A-2002-207123. In addition, a drawing method that increases the refractive index in the thickness direction can be used. Specifically, there is a method of adhering a heat-shrinkable film to one side or both sides of a film containing a polymer exhibiting positive birefringence, followed by heat treatment. The film is shrunk under the action of the shrinkage force of the heat-shrinkable film due to heat treatment to shrink the film in the length and width directions, thereby increasing the refractive index in the thickness direction, where nz>nx. A retardation film having an index ellipsoid of >ny can be obtained.

Thus, the first optical compensation layer whose refractive index characteristics exhibit the relationship of nz≧nx>ny can be produced using a polymer exhibiting any negative birefringence. In general, when using a polymer exhibiting positive birefringence, there is an advantage in that there are many types of polymers that can be selected. is advantageous in that a retardation film having excellent uniformity in the slow axis direction can be easily obtained due to the stretching method.

D. Second Optical Compensation Layer The second optical compensation layer 20 is arranged on the side opposite to the polarizing plate 40 with respect to the first optical compensation layer 10 . In the illustrated example, the second optical compensation layer 20 is arranged adjacent to the first optical compensation layer 10 . 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 .
The light transmittance range of the second optical compensation layer 20 at a wavelength of 550 nm is the same as the light transmittance range of the first optical compensation layer 10 described above.
The thickness of the second optical compensation layer 20 can be set so as to obtain desired optical properties. The thickness of the second optical compensation layer 20 is typically 1 μm or more, preferably 4 μm or more, and typically 200 μm or less, preferably 150 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.
The refractive index characteristic of the second optical compensation layer 20 exhibits the relationship of nx>ny as described above, and typically exhibits the relationship of nz≧nx>ny or the relationship of nx>ny≧nz. A layer (film) exhibiting refractive index characteristics of nx>ny=nz may be referred to as a “positive A plate” or the like. A layer (film) exhibiting refractive index characteristics of nx>ny>nz may be referred to as a “negative B plate” or the like.

When the refractive index characteristics of the second optical compensation layer 20 show the relationship of nz≧nx>ny, the second optical compensation layer 20 is formed in the same manner as the first optical compensation layer described in section C above.
When the refractive index characteristics of the second optical compensation layer 20 show the relationship of nx>ny≧nz, any suitable material can be used as the material for forming the second optical compensation layer 20 as long as the above characteristics can be obtained. can be adopted. The second optical compensation layer 20 is typically composed of a retardation film (stretched polymer film).

Any appropriate resin can be adopted as the resin that forms the polymer film. Specific examples include resins that constitute positive birefringent films, such as norbornene-based resins, polycarbonate-based resins, cellulose-based resins, polyvinyl alcohol-based resins, and polysulfone-based resins. Among them, norbornene-based resins and polycarbonate-based resins are preferable.

The norbornene-based resin is a resin that is polymerized using a norbornene-based monomer as a polymerization unit. The norbornene-based monomers include, for example, norbornene and its alkyl and/or alkylidene-substituted products such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl -2-norbornene, 5-ethylidene-2-norbornene and the like, polar group-substituted products thereof such as halogen; dicyclopentadiene, 2,3-dihydrodicyclopentadiene and the like; dimethanooctahydronaphthalene, its alkyl and/or alkylidene substituents, and polar group substituents such as halogen, for example, 6-methyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6- ethyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4:5,8-dimethano-1,4, 4a,5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4:5,8-dimethano-1, 4,4a,5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octa hydronaphthalene, etc.; tri- to tetra-mers of cyclopentadiene, such as 4,9:5,8-dimethano-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzoindene, 4, 11:5,10:6,9-trimethano-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-dodecahydro-1H-cyclopentanthracene. The norbornene-based resin may be a copolymer of norbornene-based monomers and other monomers.

The polycarbonate-based resin includes, for example, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di-, tri- or polyethylene glycol, and and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alkylene glycols or spiroglycols. The polycarbonate-based resin preferably contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from spiroglycol. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds as necessary. The details of the polycarbonate resin that can be preferably used in the present invention are, for example, JP-A-2014-10291, JP-A-2014-26266, JP-A-2015-212816, JP-A-2015-212817. , JP-A-2015-212818, which is incorporated herein by reference.

A retardation film (stretched film) corresponding to the second optical compensation layer can be obtained by stretching the polymer film under any appropriate stretching conditions. Specifically, the desired optical properties (e.g., refraction A retardation film (second optical compensation layer) having a retardation property, an in-plane retardation, and a retardation in the thickness direction can be obtained. In particular, Re ² (550) and Rth ² (550) of the second optical compensation layer can be adjusted within the ranges described above by adjusting the thickness (original film thickness), stretching temperature, and stretching ratio of the polymer film. can.
The thickness of the polymer film (original fabric thickness) is typically 5 μm or more, preferably 10 μm or more, and typically 210 μm or less, preferably 160 μm or less, more preferably 50 μm or less, and still more preferably 40 μm or less. be.
The stretching temperature is preferably 120° C. or higher and 170° C. or lower, more preferably 130° C. or higher and 160° C. or lower. The draw 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 side opposite to the first optical compensation layer 10 with respect 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 light transmittance range of the third optical compensation layer 30 at a wavelength of 550 nm is the same as the light transmittance range of the first optical compensation layer 10 described above.
The thickness of the third optical compensation layer 30 can be set so as to obtain desired optical properties. The thickness of the third optical compensation layer 30 is typically 1 μm or more, preferably 4 μm or more, and typically 200 μm or less, preferably 150 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

The refractive index characteristic of the third optical compensation layer 30 exhibits the relationship of nx>ny as described above, and typically exhibits the relationship of nz≧nx>ny or the relationship of 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 is formed in the same manner as the first optical compensation layer described in section C above.
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 is the second optical compensation layer (refractive index characteristics; nx>ny ≧nz).

F. Image Display Device The optical layered body according to the above 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 laminate. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. In particular, the optical layered body described above can reduce the reflection brightness of the image display device, and thus can be suitably applied to the organic EL display device. An image display device according to an embodiment of the present invention includes an image display cell and the optical layered body according to items A to E above. Typically, an image display device includes an image display panel including image display cells, and the optical layered body arranged on the viewing side thereof. An image display device may be called an optical display device, an image display panel may be called an optical display panel, and an image display cell may be called an optical display cell.

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

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

<Preparation of Retardation Film (Negative A Plate) with Refractive Index Characteristics nz=nx>ny>
<<Production Example 1>>
Styrene-maleic anhydride copolymer (manufactured by Nova Chemical Japan, trade name "Dylark D232") pellet-shaped resin is extruded at 270 ° C. using a single-screw extruder and a T-die to form a sheet-shaped molten resin. was cooled with a cooling drum to obtain a film having a thickness of 40 μm. This film was longitudinally stretched in the transport direction using a roll stretcher at a temperature of 130° C. and a stretch ratio of 2.0 to obtain a retardation film having a fast axis in the transport direction.
The retardation film thus obtained exhibited a relationship of nz=nx>ny in terms of refractive index characteristics. Tables 1 to 3 show the in-plane retardation Re(550), thickness direction retardation Rth(550) and Re(450)/Re(550) of the retardation film (negative A plate).
<<Production Example 2-12>>
A film (thickness 40 μm) before stretching obtained in the same manner as in Production Example 1 was longitudinally stretched at 130° C. so that the in-plane retardation Re (550) was the value shown in Tables 1 to 3. A retardation film (negative A plate) was obtained.

<Preparation of Retardation Film (Positive B Plate) with Refractive Index Properties of nz>nx>ny>
<<Production Example 13-17>>
A film (thickness: 40 μm) before stretching obtained in the same manner as in Production Example 1 was stretched so that the in-plane retardation Re (550) and the thickness direction retardation Rth (550) were the values shown in Tables 1 to 3. Then, the film was longitudinally stretched at 130° C. at fixed ends in the transport direction to obtain a retardation film.
The retardation film thus obtained exhibited a refractive index characteristic of nz>nx>ny. Tables 1 to 3 show the in-plane retardation Re(550), thickness direction retardation Rth(550), Re(450)/Re(550) and Nz coefficient of the retardation film (positive B plate).

<Preparation of Retardation Film (Positive A Plate) with Refractive Index Characteristics nx>ny=nz>
<<Production Example 18>>
A long norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name Zeonor, thickness 40 μm, photoelastic coefficient 3.10×10 ⁻¹² m ² /N) is longitudinally stretched at 130° C. to 1.1 times at the free end. to obtain a retardation film with a thickness of 38 μm.
The retardation film thus obtained exhibited a refractive index characteristic of nx>ny=nz. Tables 1 to 4 show the in-plane retardation Re(550), thickness direction retardation Rth(550), Re(450)/Re(550), and Nz coefficient of the retardation film (positive A plate).
<<Production Example 19-31>>
A norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name Zeonor, thickness 40 μm) is longitudinally stretched at the free end at 130 ° C. so that the in-plane retardation Re (550) is the value shown in Tables 1 to 4. A retardation film (positive A plate) was obtained. The retardation film of Production Example 30 has Re(550) of 270 nm and functions as a λ/2 plate. The retardation film of Production Example 31 has Re(550) of 135 nm and functions as a λ/4 plate.

<<Production Example 32>>
29.60 mass of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane was added to a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. part (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 the interior of the reactor was replaced with nitrogen under reduced pressure, heating was performed with a heating medium, and stirring was started when the internal temperature reached 100°C. After 40 minutes from the start of heating, the internal temperature was allowed to reach 220°C, and the pressure was reduced at the same time as controlling to maintain this temperature. Phenol vapor produced as a by-product of the polymerization reaction was led to a reflux condenser at 100°C, a small amount of monomer components contained in the phenol vapor was returned to the reactor, and uncondensed phenol vapor was led to a condenser at 45°C and recovered. After nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature rise and pressure reduction in the second reactor were started, and the internal temperature was brought to 240° C. and the pressure to 0.2 kPa in 50 minutes. After that, polymerization was allowed to proceed until a predetermined stirring power was obtained. When a predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, the polyester carbonate-based resin produced was extruded into water, and strands were cut to obtain pellets.
After vacuum drying the obtained polyester carbonate resin (pellet) at 80 ° C. for 5 hours, a single screw extruder (Toshiba Machine Co., Ltd., cylinder setting temperature: 250 ° C.), T die (width 200 mm, setting temperature: 250 ° C.), a chill roll (set temperature: 120 to 130° C.) and a film forming apparatus equipped with a winder to prepare a long resin film having a thickness of 130 μm. The obtained long resin film was longitudinally stretched 1.2 times at the free end at 140° C. to obtain a retardation film (positive A plate) with a thickness of 120 μm.
<<Production Examples 33-36>>
The resin film (thickness 130 μm) before stretching obtained in the same manner as in Production Example 32 was longitudinally stretched at the free end at 140° C. so that the in-plane retardation Re (550) was the value shown in Tables 1 to 4. to obtain a retardation film (positive A plate). The retardation film of Production Example 36 has Re(550) of 140 nm and functions as a λ/4 plate.

<Preparation of Retardation Film (Negative B Plate) with Refractive Index Properties of nx>ny>nz>
<<Production Example 37-40>>
A norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name Zeonor, thickness 40 μm) was prepared so that the in-plane retardation Re (550) and the thickness direction retardation Rth (550) were the values shown in Tables 1 to 4. , and fixed-end transverse stretching at 135° C. to obtain a retardation film.
The thus-obtained retardation film exhibited a relationship of nx>ny>nz in terms of refractive index characteristics. Tables 1 to 3 show the in-plane retardation Re(550), thickness direction retardation Rth(550), Re(450)/Re(550) and Nz coefficient of the retardation film (negative B plate).

<Preparation of Retardation Film (Positive C Plate) with Refractive Index Characteristics of nz>nx=ny>
<<Production Examples 41 and 42>>
A retardation film (positive C plate) was obtained in the same manner as in Production Example 6 of Japanese Patent No. 6896118, except that the retardation Rth(550) was changed to the value shown in Table 4.
The retardation film thus obtained exhibited a refractive index characteristic of nz>nx=ny. Table 4 shows the in-plane retardation Re (550) and the thickness direction retardation Rth (550) of the retardation film (positive C plate).

<Preparation of polarizing plate>
<<Production Example 43>>
A long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to corona treatment.
Polyvinyl alcohol (degree of polymerization: 4,200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: "GOSEFIMER") were mixed at a ratio of 9:1, and 100 parts by mass of PVA-based resin. was added with 13 parts by mass of potassium iodide and dissolved in water to prepare an aqueous PVA solution (coating solution).
The above 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 having a thickness of 13 μm, thereby producing a laminate.
The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (an aqueous boric acid solution obtained by blending 4 parts by mass of boric acid with 100 parts by mass of water) at a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment).
Then, the finally obtained polarizer is added to a dyeing bath (iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by mass of water) at a liquid temperature of 30 ° C. It was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) was a desired value (dyeing treatment).
Then, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by blending 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with respect to 100 parts by mass of water). (crosslinking treatment).
After that, while immersing the laminate in an aqueous solution of boric acid (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70° C., the laminate was moved vertically (longitudinally) between rolls with different peripheral speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
After that, the laminate was immersed in a cleaning bath having a liquid temperature of 20° C. (an aqueous solution obtained by mixing 100 parts by mass of water with 4 parts by mass of potassium iodide) (cleaning treatment).
Thereafter, while drying in an oven maintained at about 90° C., it was brought into contact with a heating roll made of SUS whose surface temperature was maintained at about 75° C. (dry shrinkage treatment).
In this way, a polarizer having a thickness of about 5 μm was formed on the resin substrate to obtain a laminate having a structure of resin substrate/polarizer.
An HC-TAC film (thickness: 20 μm) was attached as a protective layer to the polarizer surface (the surface opposite to the resin substrate) of the obtained laminate. Then, the resin substrate was peeled off to obtain a polarizing plate having a structure of protective layer/polarizer/.

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

[Example 1-9]
Each of the retardation film of Production Example and the polarizing plate of Production Example 43 shown in Table 1 was punched into a size corresponding to an image display cell. Further, the retardation film of each production example, as shown in Table 1, the first retardation film corresponding to the first optical compensation layer, the second retardation film corresponding to the second optical compensation layer, the third and the third retardation film corresponding to the optical compensation layer.
Next, 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 a polarizing plate were laminated in this order. In the lamination, the angle between the absorption axis direction of the polarizer and the slow axis direction of the optical compensation layer (each of the first optical compensation layer, the second optical compensation layer and the third optical compensation layer) is the value shown in Table 1. I made it so that
Thus, an image display device was produced. The image display device was then subjected to the reflection luminance measurement described above.

[Examples 10-18]
Each of 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) was prepared according to the production examples shown in Table 2. An image display device was produced in the same manner as in Example 1, except that the retardation film was used. The image display device was then subjected to the reflection luminance measurement described above.

[Examples 19-27]
Each of 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) was prepared according to the production examples shown in Table 3. An image display device was produced in the same manner as in Example 1, except that the retardation film was used. The image display device was then subjected to the reflection luminance measurement described above.

[Comparative Examples 1 and 2]
The first retardation film (first optical compensation layer) and the second retardation film (second optical compensation layer) were changed to the retardation film of the production example shown in Table 4, and the third retardation film ( An image display device was produced in the same manner as in Example 1, except that the third optical compensation layer) was not provided. The image display device was then subjected to the reflection luminance measurement described above.
[Comparative Example 3]
Each of 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) was prepared according to the production examples shown in Table 4. An image display device was produced in the same manner as in Example 1, except that the retardation film was used. The image display device was then subjected to the reflection luminance measurement described above.

[evaluation]
As is clear from Tables 1 to 4, the refractive index characteristics of the first optical compensation layer show a relationship of nz≧nx>ny, and the refractive index characteristics of the second optical compensation layer and/or the third optical compensation layer are nx. >ny≧nz>, each of Re ¹ (550), Re ² (550) and Re ³ (550) is 10 nm or more and 220 nm or less, the first optical compensation layer, the second optical compensation layer and When the third optical compensation layer satisfies the above formula (1), it is possible to realize an image display device (organic EL display device) with remarkably low reflection luminance.

The optical layered body according to the embodiment of the present invention can be suitably applied to image display devices (typically, liquid crystal display devices and organic EL display devices).

REFERENCE SIGNS LIST 10 first optical compensation layer 20 second optical compensation layer 30 third optical compensation layer 40 polarizing plate 41 polarizer 100 optical laminate

Claims (22)

a polarizer;
a first optical compensation layer whose refractive index characteristics exhibit a relationship of nz≧nx>ny;
a second optical compensation layer whose refractive index characteristics exhibit a relationship of nx>ny;
and a third optical compensation layer whose refractive index characteristics exhibit a relationship of nx>ny in this order,
refractive index characteristics of the second optical compensation layer and/or the third optical compensation layer exhibit a relationship of nx>ny≧nz;
In-plane retardation Re ¹ (550) of the first optical compensation layer, in-plane retardation Re ² (550) of the second optical compensation layer, and in-plane retardation Re ³ (550) of the third optical compensation layer is 10 nm or more and 220 nm or less,
the absorption axis direction of the polarizer and the slow axis direction of the first optical compensation layer intersect without being substantially orthogonal,
An optical laminate in which the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer satisfy the following formula (1):

(In formula (1), Rth ¹ (550) represents the retardation in the thickness direction of the first optical compensation layer; Rth ² (550) represents the retardation in the thickness direction of the second optical compensation layer; Rth ³ (550) represents the retardation in the thickness direction of the third optical compensation layer; Re ¹ (550) represents the in-plane retardation of the first optical compensation layer; Re ² (550) represents the second optical represents the in-plane retardation of the compensation layer; Re ³ (550) represents the in-plane retardation of the third optical compensation layer). 2. The optical laminate according to claim 1, wherein refractive index characteristics of said second optical compensation layer and said third optical compensation layer exhibit a relationship of nx>ny≧nz. 3. The optical laminate according to claim 2, wherein the in-plane retardation ^Re2 (550) of the second optical compensation layer is 180 nm or less. 4. The optical laminate according to claim 2, wherein the in-plane retardation ^Re1 (550) of the first optical compensation layer is 50 nm or more and 180 nm or less. 5. The optical laminate according to claim 4, wherein the in-plane retardation ^Re1 (550) of the first optical compensation layer is 100 nm or less. The optical laminate according to any one of claims 2 to 4, wherein the in-plane retardation Re ³ (550) of the third optical compensation layer is 180 nm or less. The refractive index characteristics of the first optical compensation layer exhibit a relationship of nz=nx>ny,
7. The optical laminate according to any one of claims 2 to 6, wherein refractive index characteristics of said second optical compensation layer and said third optical compensation layer exhibit a relationship of nx>ny=nz. The refractive index characteristics of the second optical compensation layer exhibit a relationship of nx>ny≧nz,
2. The optical laminate according to claim 1, wherein refractive index characteristics of said third optical compensation layer exhibit a relationship of nz≧nx>ny. 9. The optical laminate according to claim 8, wherein the in-plane retardation ^Re2 (550) of the second optical compensation layer is 50 nm or more and 180 nm or less. 10. The optical laminate according to claim 9, wherein the in-plane retardation ^Re2 (550) of the second optical compensation layer is 100 nm or more. The optical laminate according to any one of claims 8 to 10, wherein the in-plane retardation Re ³ (550) of the third optical compensation layer is 60 nm or more and 180 nm or less. The optical laminate according to any one of claims 8 to 11, wherein the in-plane retardation Re ¹ (550) of the first optical compensation layer is 120 nm or less. Refractive index characteristics of each of the first optical compensation layer and the third optical compensation layer exhibit a relationship of nz=nx>ny,
The optical laminate according to any one of claims 8 to 12, wherein refractive index characteristics of said second optical compensation layer exhibit a relationship of nx>ny=nz. The refractive index characteristic of the second optical compensation layer exhibits a relationship of nz≧nx>ny,
2. The optical laminate according to claim 1, wherein refractive index characteristics of said third optical compensation layer exhibit a relationship of nx>ny≧nz. 15. The optical laminate according to claim 14, wherein the in-plane retardation ^Re2 (550) of the second optical compensation layer is 50 nm or more and 180 nm or less. The optical laminate according to claim 14 or 15, wherein the in-plane retardation Re ³ (550) of the third optical compensation layer is 50 nm or more. 17. The optical laminate according to claim 16, wherein the in-plane retardation ^Re3 (550) of the third optical compensation layer is 90 nm or more. The optical laminate according to any one of claims 14 to 17, wherein the in-plane retardation ^Re3 (550) of the third optical compensation layer is 180 nm or less. The optical laminate according to any one of claims 14 to 18, wherein the in-plane retardation Re ¹ (550) of the first optical compensation layer is 50 nm or more and 180 nm or less. Refractive index characteristics of the first optical compensation layer and the second optical compensation layer exhibit a relationship of nz=nx>ny,
The optical laminate according to any one of claims 14 to 19, wherein refractive index characteristics of said third optical compensation layer exhibit a relationship of nx>ny=nz. wherein, of the second optical compensation layer and the third optical compensation layer, Re(450)/Re(550) of the optical compensation layer exhibiting a relationship of nx>ny≧nz in refractive index characteristics is less than 1. Item 21. The optical laminate according to any one of Items 1 to 20. an image display cell;
An image display device comprising the optical layered body according to any one of claims 1 to 21.

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