KR20240024067A - display device - Google Patents

Abstract

[Problem] The present invention provides a display device (1) that can suppress reflected light reflected from the high refractive index layer (45) from entering the light receiving sensor (42), and also provides an optical device used in the display device (1). A laminate 51 is also provided.
[Solution] The display device 1 of the present invention has a high refractive index layer 42, a first phase difference layer 31, a linear polarization layer 11, and a display unit 40 in this order from the viewer side. . The refractive index of the high refractive index layer 42 is 1.60 or more. The display unit 40 has a display element 41 and a light receiving sensor 42 . The first phase difference layer 31 and the linear polarization layer 11 are stacked so as to cover the display element 41 and the light receiving sensor 42.

Description

display device

The present invention relates to a display device, and further relates to an optical laminated body used therein.

A polarizing plate containing a linear polarizing layer serves as a supply element of polarized light in a display device such as a liquid crystal display device or an organic electroluminescence (EL) display device, as a detection element of polarized light, and as a detection element for reflected light reflected by the display element. It is widely used to suppress the emission of light outside. Display devices equipped with polarizers are also deployed in mobile devices such as notebook-type personal computers, smart phones, and tablet terminals. In Patent Document 1, from the viewpoint of expansion of the display area and design on the display surface of a mobile device such as a smart phone, for example, when viewed in a plan view, the outer edge of the display area is cut into a concave shape to provide a non-display area. It is listed.

Typically, a display element and a polarizing plate are not disposed in the non-display area provided in the concave shape. Therefore, by arranging various sensors such as camera lenses and light-receiving sensors in the non-display area, it is possible to make it difficult to adversely affect camera performance and sensor sensitivity.

Patent Document 1: Japanese Patent Publication No. 2019-219528

In order to further expand the display area on the display screen, it is required to reduce the non-display area. In this case, it is considered to arrange various sensors, such as a light receiving sensor, in the display area where the display element and the polarizing plate are provided. When a light-receiving sensor is disposed within the display area, light emitted from the display element is reflected by the high refractive index layer disposed on the viewing side of the polarizing plate and is likely to enter the light-receiving sensor. Reflected light incident on the light receiving sensor is likely to cause malfunction of the light receiving sensor.

The purpose of the present invention is to provide a display device that can prevent reflected light reflected from the high refractive index layer from entering the light receiving sensor even if the display device has a high refractive index layer on the viewing side, and an optical laminate used therein.

The present invention provides the following display device.

[1] A display device having a high refractive index layer, a first retardation layer, a linear polarization layer, and a display unit in this order from the viewing side,

The refractive index of the high refractive index layer is 1.60 or more,

The display unit has a display element and a light receiving sensor,

The first phase difference layer and the linear polarization layer are stacked so as to cover the display element and the light receiving sensor.

[2] The display device according to [1], wherein the first retardation layer covers the entire surface on the viewing side of the linear polarization layer when viewed in plan.

[3] The display device according to [1] or [2], wherein the visibility-corrected single transmittance of the linear polarizing layer is 42% or more.

[4] The display device according to any one of [1] to [3], wherein the angle formed between the slow axis of the first retardation layer and the absorption axis of the linear polarization layer is 10° or more and 80° or less.

[5] The display device according to any one of [1] to [4], wherein the in-plane retardation value of the first phase difference layer at a wavelength of 550 nm is 80 nm or more and 170 nm or less.

[6] The display device according to [5], wherein the first phase difference layer has reverse wavelength dispersion.

[7] Further having a second phase difference layer between the high refractive index layer and the linear polarization layer,

The second phase difference layer is laminated to cover the display element and the light receiving sensor,

The display device according to [5] or [6], wherein the thickness direction retardation value of the second retardation layer at a wavelength of 550 nm is -140 nm or more and -20 nm or less.

[8] The display device according to any one of [1] to [7], wherein the stimulus value Y of the reflected light when the light emitted from the display element is reflected by the high refractive index layer is 3.45% or more and 4.54% or less.

[9] The display device according to any one of [1] to [8], wherein the light receiving sensor is capable of detecting light with a wavelength of 320 nm or more and 4000 nm or less.

[10] The display device according to any one of [1] to [9], wherein the light emitted from the display element has a wavelength of 320 nm or more and 4000 nm or less.

[11] The display device according to any one of [1] to [10], further comprising a third phase difference layer between the linear polarization layer and the display unit.

The present invention provides the following optical laminate.

[12] An optical laminate having a high refractive index layer, a first retardation layer, and a linear polarization layer in this order,

An optical laminate wherein the high refractive index layer has a refractive index of 1.60 or more.

[13] The optical laminate according to [12], wherein the first retardation layer covers the entire surface on the viewing side of the linear polarization layer in plan view.

[14] The optical laminate according to [12] or [13], wherein the linear polarization layer has a visibility-corrected single transmittance of 42% or more.

[15] The optical laminate according to [12] or [13], wherein the angle formed between the slow axis of the first retardation layer and the absorption axis of the linear polarization layer is 10° or more and 80° or less.

[16] The optical laminate according to [12] or [13], wherein the in-plane retardation value of the first retardation layer at a wavelength of 550 nm is 80 nm or more and 170 nm or less.

[17] The optical laminate according to [12] or [13], wherein the first phase contrast layer has reverse wavelength dispersion.

[18] Further having a second phase difference layer between the high refractive index layer and the linear polarization layer,

The optical laminate according to [12] or [13], wherein the thickness direction retardation value of the second retardation layer at a wavelength of 550 nm is -140 nm or more and -20 nm or less.

[19] The optical laminate according to [12] or [13], further comprising a third retardation layer on a side of the linear polarizing layer opposite to the first retardation layer.

According to the display device of the present invention, it is possible to suppress reflected light reflected from the high refractive index layer from entering the light receiving sensor. Furthermore, according to the optical laminate of the present invention, the display device of the present invention can be provided.

1 is a schematic cross-sectional view schematically showing a display device according to an embodiment of the present invention.
Figure 2 is a schematic cross-sectional view schematically showing a display device according to another embodiment of the present invention.
3 is a schematic cross-sectional view schematically showing a display device according to another embodiment of the present invention.
4 is a schematic cross-sectional view schematically showing a display device according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the display device and the optical laminated body will be described with reference to the drawings. In each drawing, members that are the same as those explained previously are given the same reference numerals and their descriptions are omitted.

[Embodiment 1]

(Display device and optical laminate)

1 and 2 are schematic cross-sectional views schematically showing a display device according to an embodiment of the present invention. In Figures 1 and 2, the upper side is the viewing side. 1 and 2, the display devices 1 and 2 of the present embodiment include, from the viewer side, a high refractive index layer 45, a first phase difference layer 31, a linear polarization layer 11, and a display layer. We have the units 40 in this order. Among these, the high refractive index layer 45, the first retardation layer 31, and the linear polarization layer 11 constitute the optical laminates 51 and 52. The refractive index of the high refractive index layer 45 is 1.60 or more, preferably 1.75 or more, more preferably 1.80 or more, usually 2.70 or less, preferably 2.40 or less, more preferably 2.30 or less, and further Preferably it is 2.10 or less. The refractive index of the high refractive index layer 45 can be measured by the method described in the Examples described later.

The display unit 40 has a display element 41 and a light receiving sensor 42 . As shown in FIGS. 1 and 2 , the display unit 40 may have a structure in which the light receiving sensor 42 is stacked on the viewing side of the display element 41, and the display unit 40 may have a structure in which the light receiving sensor 42 is stacked on the viewing side of the display element 41. It may have a structure in which the light receiving sensor 42 is stacked on the opposite side. Alternatively, the light receiving sensor 42 may be inserted into a through hole or recess provided in the display element 41. In the display unit 40, the area of the display element 41 can be used as the display area of the display devices 1 and 2, so from the viewpoint of enlarging the display area, when viewed from the plane of the display unit 40, light reception is possible. It is preferable that the area of the display element 41 exists so as to surround the sensor 42.

In the display devices 1 and 2, the first phase difference layer 31 and the linear polarization layer 11 are laminated so as to cover the display element 41 and the light receiving sensor 42. The first phase difference layer 31 and the linear polarization layer 11 cover the entire surface on the viewer side of the display unit 40, that is, the entire surface on the viewer side of the display element 41 and the light receiving sensor 42. It is preferable that they are laminated so as to cover them. By providing the linear polarization layer 11 as described above, the area of the display element 41 around the light receiving sensor 42 is covered by the linear polarization layer 11 when viewed in plan view, so that the display device 1 , 2) It becomes easier to enlarge the display area. As long as the first phase difference layer 31 is laminated so as to cover the display element 41 and the light-receiving sensor 42, it may cover the entire linear polarization layer 11 in a plan view, or may cover a part of it. The planar shape of the first retardation layer 31 may be the same as or different from the planar shape of the linear polarization layer 11.

In the display devices 1 and 2, image display is performed using light emitted from the display element 41. Part of the light emitted from the display element 41 may be reflected by the high refractive index layer 45 and enter the light receiving sensor 42, as indicated by the arrow in FIG. 1 . In particular, when viewed from the plane of the display unit 40, the area of the display element 41 around the light receiving sensor 42 is such that, for example, the areas of the light receiving sensor 42 and the display element 41 are adjacent to each other and exist close to each other. In this arrangement, the reflected light reflected by the high refractive index layer 45 is likely to enter the light receiving sensor 42. When reflected light enters the light receiving sensor 42, malfunction of the light receiving sensor 42 is likely to occur. In the display devices 1 and 2 of this embodiment, the first phase difference layer 31 is laminated on the viewing side of the linear polarization layer 11 that covers the display element 41 and the light receiving sensor 42. The reflected light reflected by the high refractive index layer 45 enters the first phase difference layer 31 and changes phase as it passes through the first phase difference layer 31. Therefore, at least part of the reflected light that has passed through the first phase difference layer 31 is easily absorbed by the linear polarization layer 11. As a result, the amount of reflected light incident on the light receiving sensor 42 can be reduced, so malfunction of the light receiving sensor 42 can be suppressed.

The visibility corrected single transmittance of the linear polarization layer 11 is preferably 42% or more, more preferably 43% or more, and may be 45% or more. When the visibility correction single transmittance of the linearly polarized layer 11 increases, the amount of reflected light passing through the linearly polarized layer 11 increases, making it easy for the light receiving sensor 42 to malfunction. According to the display devices 1 and 2 of the present embodiment, even when the linear polarization layer 11 with a large visibility correction single transmittance is used, the amount of reflected light incident on the light receiving sensor 42 is suppressed, and the light receiving sensor 42 ) malfunction can be suppressed. The visibility corrected single transmittance of the linear polarization layer 11 can be measured by the method described in the Examples described later.

The first phase difference layer 31 may have a phase difference, but it is preferable that the in-plane phase difference value Re(550) at a wavelength of 550 nm be 80 nm or more and 170 nm or less. The in-plane retardation value Re (550) of the first phase difference layer 31 is more preferably 100 nm or more, particularly preferably 130 nm or more, may be 135 nm or more, and is more preferably 160 nm or less, and is 150 nm or more. It is more preferable that it is below. The in-plane phase difference value Re (550) of the first phase difference layer 31 can be measured by the method described in the Examples described later.

When the first phase difference layer 31 has an in-plane phase difference value Re (550) in the above range, the light emitted from the display element 41 in the display devices 1 and 2 passes through the first phase difference layer 31. When it passes through, it is converted into elliptically polarized light. The reflected light (elliptically polarized light) reflected by the high refractive index layer 45 is converted into linearly polarized light by passing through the first phase difference layer 31. As a result, the reflected light that has passed through the first phase difference layer 31 is easily absorbed by the linear polarization layer 11, so that the amount of reflected light incident on the light receiving sensor 42 can be further suppressed.

When the in-plane retardation value Re (550) of the first retardation layer 31 is in the above range, the angle formed by the absorption axis of the linear polarization layer 11 and the slow axis of the first retardation layer 31 is 10° or more. It is preferable that it is within the range of 80° or less. The angle may be 30° or more, and is more preferably 40° or more. Additionally, the angle may be 60° or less, and is more preferably 50° or less.

The first phase difference layer 31, whose in-plane phase difference value Re (550) is within the above range, preferably has reverse wavelength dispersion. As a result, the wavelength range of reflected light absorbed by the linear polarization layer 11 is expanded, so that the amount of reflected light of various wavelengths incident on the light receiving sensor 42 can be suppressed.

In the display devices 1 and 2, the stimulation value Y of the reflected light when the light emitted from the display element 41 is reflected by the high refractive index layer 45 is preferably 3.45% or more and 4.54% or less. The stimulus value Y of the reflected light is the ratio of the light intensity of the reflected light to the light intensity of the light emitted from the display element 41. The smaller the stimulus value Y, the smaller the amount of reflected light reflected by the high refractive index layer 45, This indicates that it is unlikely to be the cause of malfunction of the light receiving sensor 42. The stimulation value Y of the reflected light can be measured by the method described in the Examples described later. The stimulation value Y of the reflected light may be 3.48% or more, may be 3.50% or more, may be 4.30% or less, may be 4.10% or less, may be 3.90% or less, and may be 3.76% or less.

In the display devices 1 and 2 where the excitation value Y of the emitted light is within the above range, it is easy to suppress the amount of reflected light incident on the light receiving sensor 42. When the excitation value Y of the emitted light is smaller than the above range, it is considered that the refractive index of the high refractive index layer 45 is small or the visibility correction single transmittance of the linear polarization layer 11 is small. Therefore, in a display device where the excitation value Y of the emitted light is smaller than the above range, the amount of reflected light incident on the light receiving sensor 42 is small, and malfunction of the light receiving sensor 42 is unlikely to occur. Additionally, in a display device where the excitation value Y of the emitted light is greater than the above range, the amount of reflected light incident on the light receiving sensor 42 is large, and malfunction of the light receiving sensor 42 is likely to occur.

(Layer structure of display device and optical laminate)

Hereinafter, in addition to the layers described above, layers that the display devices 1 and 2 and the optical laminates 51 and 52 may have will be described.

As shown in FIGS. 1 and 2, the display devices 1 and 2 and the optical laminates 51 and 52 have a first bonding layer 21 between the high refractive index layer 45 and the first phase difference layer 31. ) is desirable to have. The first bonding layer 21 may be in direct contact with the high refractive index layer 45 and the first phase difference layer 31.

The display devices 1 and 2 and the optical laminates 51 and 52 may have one or more second refractive index layers (not shown) separately from the high refractive index layer 45. The refractive index of the second refractive index layer can be within the refractive index range described above for the high refractive index layer 45. The second refractive index layer may be provided on the viewing side of the high refractive index layer 45, or may be provided between the high refractive index layer 45 and the first phase difference layer 31. In this case, the display devices 1 and 2 and the optical laminates 51 and 52 may have a bonding layer (a pressure-sensitive adhesive layer or adhesive layer described later) between the high refractive index layer 45 and the second refractive index layer. This bonding layer may be in direct contact with the high refractive index layer 45 and the second refractive index layer. When the display devices 1 and 2 and the optical laminates 51 and 52 have a second refractive index layer between the high refractive index layer 45 and the first phase difference layer 31, the first bonding layer 21 is , may be in direct contact with the first phase difference layer 31 and the second refractive index layer.

The display devices 1 and 2 and the optical laminates 51 and 52 preferably have a second bonding layer 22 between the first retardation layer 31 and the linear polarization layer 11. The second bonding layer 22 may be in direct contact with the first retardation layer 31 and the linear polarization layer 11.

As shown in FIGS. 1 and 2, the display devices 1 and 2 and the optical laminates 51 and 52 have a first protective film ( 12) It is okay to have it. The first protective film 12 may be a layer for protecting the surface on the viewing side of the linear polarizing layer 11, and the first protective film 12 and the linear polarizing layer 11 may constitute a linear polarizing plate. . When the display devices 1 and 2 and the optical laminates 51 and 52 have the first protective film 12, the second bonding layer 22 includes the first retardation layer 31 and the first protective film ( You may be in direct contact with 12).

When the display devices 1 and 2 and the optical laminates 51 and 52 have the first protective film 12, the display devices 1 and 2 and the optical laminates 51 and 52 have the first protective film. Although (12) and the linear polarizing layer 11 may be in direct contact, it is preferable to have the third bonding layer 23 between the first protective film 12 and the linear polarizing layer 11. The third bonding layer 23 may constitute a linear polarizing plate, and is preferably in direct contact with the first protective film 12 and the linear polarizing layer 11.

The display devices 1 and 2 have a fourth bonding layer 24 between the linear polarizing layer 11 and the display unit 40 (on the side opposite to the first phase difference layer 31 of the linear polarizing layer 11). ) is okay to have. The linear polarizing layer 11 and the display unit 40 may be in direct contact with the fourth bonding layer 24, as shown in FIG. 1 . As shown in Figs. 1 and 2, the fourth bonding layer 24 may be provided with optical laminates 51 and 52.

The display devices 1 and 2 and the optical laminates 51 and 52 are located between the linear polarization layer 11 and the display unit 40 (on the side opposite to the first phase difference layer 31 side of the linear polarization layer 11). ) may have a second protective film (not shown). The second protective film may be a layer for protecting the surface of the linear polarizing layer 11 opposite to the viewing side, and the second protective film and the linear polarizing layer 11 may constitute a linear polarizing plate. When the display devices 1 and 2 and the optical laminates 51 and 52 have a second protective film, the second protective film and the linear polarizing layer 11 may be in direct contact, and the second protective film and the linear polarizing layer 11 may be in direct contact with each other. (11) You may have a bonding layer (adhesive layer or adhesive layer described later) in between. This bonding layer may constitute a linear polarizing plate, and is preferably in direct contact with the second protective film and the linear polarizing layer 11. In this case, the fourth bonding layer 24 may be provided between the second protective film and the display unit 40, or may be in direct contact with the second protective film and the display unit 40.

As shown in FIG. 2, the display device 2 and the optical laminate 52 are located between the linear polarization layer 11 and the display unit 40 (on the first phase difference layer 31 side of the linear polarization layer 11). On the opposite side), a third phase difference layer 13 may be provided. In this case, the display device 2 and the optical laminate 52 may have a fifth bonding layer 25 between the linearly polarizing layer 11 and the third retardation layer 13, and the linearly polarizing layer 11 ) and the third phase difference layer 13 may be in direct contact with the fifth bonding layer 25. When the display device 2 and the optical laminate 52 have a second protective film, the fifth bonding layer 25 is provided between the second protective film and the third retardation layer 13, and provides the second protective film. It may be in direct contact with the film and the third retardation layer 13. In the display device 2 having the third phase difference layer 13, the fourth bonding layer 24 may be provided between the third phase difference layer 13 and the display unit 40, and the third phase difference layer 13 ) and may be in direct contact with the display unit 40. In the optical laminate 52 having the third phase difference layer 13, the fourth bonding layer 25 may be in direct contact with the third phase difference layer 13. The linear polarization layer 11 and the third retardation layer 13 preferably form a circularly polarizing plate, and the third retardation layer 13 is preferably a λ/4 retardation layer, and more preferably has reverse wavelength dispersion. It is a λ/4 phase difference layer.

The display device 2 and the optical laminate 52 are located between the linear polarization layer 11 and the display unit 40 (on the side opposite to the first retardation layer 31 of the linear polarization layer 11). 3. Separate from the phase difference layer 13, you may have one or more fourth phase difference layers (not shown). The fourth retardation layer may be provided between the linear polarization layer 11 and the third retardation layer 13, or between the third retardation layer 13 and the display unit 40 (of the third retardation layer 13). It may be provided on the side opposite to the linear polarization layer 11 side. In this case, you may have a bonding layer (pressure-sensitive adhesive layer or adhesive layer described later) between the third retardation layer 13 and the fourth retardation layer, and this bonding layer is attached to the third retardation layer 13 and the fourth retardation layer. It's okay to experience it directly. When the display device 2 and the optical laminate 52 have a fourth retardation layer between the linear polarizing layer 11 and the third retardation layer 13, the fifth bonding layer 25 is connected to the linear polarizing layer 11. ) and may be in direct contact with the fourth phase difference layer. When the display device 2 has a fourth retardation layer between the third retardation layer 13 and the display unit 40, the fourth bonding layer 24 is in direct contact with the fourth retardation layer and the display unit 40. It's okay to have it. When the optical laminate 52 has a third retardation layer on the side opposite to the linear polarization layer 11 side of the third retardation layer 13, the fourth retardation layer may be in direct contact with the fourth bonding layer. It is preferable that the linear polarization layer 11, the third retardation layer 13, and the fourth retardation layer constitute a circularly polarizing plate. The fourth retardation layer constituting the circularly polarizing plate is preferably a λ/2 retardation layer or a positive C layer.

[Embodiment 2]

3 and 4 are schematic cross-sectional views schematically showing a display device according to another embodiment of the present invention. In Figures 3 and 4, the upper side is the viewing side. In that the display devices 3 and 4 and the optical laminates 53 and 54 of the present embodiment have a second phase difference layer 32 between the high refractive index layer 45 and the linear polarization layer 11, Since it is different from the display devices 1 and 2 and the optical laminates 51 and 52 described in the previous embodiment, this point will be explained below.

In the display devices 3 and 4, the second phase difference layer 32 is laminated so as to cover the display element 41 and the light receiving sensor 42. The second phase difference layer 32 is laminated so as to cover the entire surface on the viewing side of the display unit 40, that is, covering the entire surface on the viewing side of the display element 41 and the light receiving sensor 42. desirable.

The display devices 3 and 4 and the optical laminates 53 and 54 shown in FIGS. 3 and 4 have a second phase difference layer 32 between the high refractive index layer 45 and the first phase difference layer 31. . The second retardation layer 32 preferably covers the entire first retardation layer 31 when viewed in plan, and the planar shape of the second retardation layer 32 is that of the first retardation layer 31. It is more preferable that the shape is identical to the shape seen in plan view.

The second phase difference layer 32 may have a phase difference, but it is preferable that the thickness direction phase difference value Rth (550) at a wavelength of 550 nm is -140 nm or more and -20 nm or less. The thickness direction retardation value Rth (550) of the second phase difference layer 32 may be greater than -140 nm, may be greater than -120 nm, may be greater than -100 nm, may be greater than -90 nm, and may be greater than -20 nm. It may be less than, -30 or less may be sufficient, -40 or less may be sufficient, and -50 or less may be sufficient.

The thickness direction retardation value Rth (550) of the second retardation layer 32 is a value calculated based on the following equation (i).

Rth(550)=[{(nx+ny)/2}-nz]×d (i)

[In equation (i),

nx is the main refractive index at a wavelength of 550 nm in the plane of the second phase difference layer 32,

ny is the refractive index at a wavelength of 550 nm in the same plane as nx and in the direction orthogonal to nx,

nz is the refractive index at a wavelength of 550 nm in the thickness direction of the second retardation layer 32, and when nx=ny, nx is the refractive index in an arbitrary direction within the plane of the second retardation layer 32. You can do it,

d is the film thickness of the second phase difference layer 32.]

By having the display devices 3 and 4 with the second phase difference layer 32, as indicated by the arrow in FIG. 3, the amount of light is reduced also for the reflected light incident on the light receiving sensor 42 from an oblique direction. can do. The reflected light incident from the oblique direction is mainly the light emitted from the area away from the light-receiving sensor 42 in the display element 41 when viewed from the plane of the display unit 40, and is the light reflected by the high refractive index layer 45. . The amount of reflected light incident from the oblique direction is likely to be reduced when the thickness direction retardation value Rth (550) of the second retardation layer 32 is in the above range. Thereby, malfunction of the light receiving sensor 42 can be further suppressed.

3 and 4, the first bonding layer 21 may be provided between the high refractive index layer 45 and the second phase difference layer 32, and the high refractive index layer 45 and the second phase difference layer You may be in direct contact with (32). The display devices 3 and 4 and the optical laminates 53 and 54 have a sixth bonding layer 26 between the second phase difference layer 32 and the first phase difference layer 31, and the second phase difference layer ( 32) and the first phase difference layer 31 is preferably in direct contact with the sixth bonding layer 26.

In the display devices 3 and 4 and the optical laminates 53 and 54 shown in FIGS. 3 and 4, a second retardation layer 32 is provided between the high refractive index layer 45 and the first retardation layer 31. Although the case is described, it is not limited to this as long as the second retardation layer 32 is provided between the high refractive index layer 45 and the linear polarization layer 11. For example, the second phase difference layer 32 may be provided between the first phase difference layer 31 and the linear polarization layer 11. In this case, the second retardation layer 32 preferably covers the entire linear polarization layer 11. The planar shape of the second phase difference layer 32 is preferably the same as the planar shape of the first phase difference layer 31.

Even when the display devices 3 and 4 and the optical laminates 53 and 54 have a second retardation layer 32 between the first retardation layer 31 and the linear polarization layer 11, the display device 3, 4) and the optical laminates 53 and 54 may have a sixth bonding layer 26 between the second phase difference layer 32 and the first phase difference layer 31. In addition, the second bonding layer 22 may be provided between the second retardation layer 32 and the linear polarization layer 11. For example, the second bonding layer 22 may be formed between the second retardation layer 32 and the second bonding layer 22. 1 You may be in direct contact with the protective film 12.

Hereinafter, the display device described above and the layers constituting the display device will be described in more detail.

(display device)

The above display device can be used as a liquid crystal display device or an organic EL (electroluminescence) display device. The display device may be a portable terminal such as a smartphone or tablet. The display device may be a flexible display that can be bent.

The planar appearance of the display area of the display device is not particularly limited, but may be a rectangle, a square, a polygon other than a rectangle or a square, or a round angle where each of these angles is a round angle (a shape with rounding). The display area in the shape of a rectangle, square, polygon, or round angle may have a through hole for arranging a camera or the like.

(display element)

The display element may be a liquid crystal display element or an organic EL display element. The liquid crystal display element may have, for example, a liquid crystal cell and a backlight in which a liquid crystal layer is sandwiched between two cell substrates. The organic EL display element may have, for example, a light emitting layer and an electrode.

The light emitted from the display element is preferably light with a wavelength of 320 nm or more and 4000 nm or less, more preferably light with a wavelength of 380 nm or more and 780 nm or less (visible light region), and may be light with a wavelength of 380 nm or more and 720 nm or less. good night.

(light receiving sensor)

The light receiving sensor detects incident light. The light receiving sensor may be an illuminance sensor that detects the illuminance around the display device, a proximity sensor that detects the proximity of an object, or a camera. The light receiving sensor is preferably capable of detecting light with a wavelength of 320 nm or more and 4000 nm or less, light with a wavelength of 380 nm or more and 780 nm or less (visible light region), and/or light with a wavelength of 780 nm or more and 4000 nm or less (infrared region). It is more desirable to be able to detect light.

(Touch sensor panel)

The display device and the optical laminate may include a touch sensor panel. The touch sensor panel can detect the position touched by the user with a finger or the like. Examples of the touch sensor panel include touch sensor panels such as resistive type, capacitive coupling type, optical sensor type, ultrasonic type, electromagnetic inductive coupling type, and surface acoustic wave type, among which resistive type and capacitive bonding type. A touch sensor panel of this type is suitably used.

In the display device and the optical laminate, the touch sensor panel may be provided on the viewing side of the linear polarizing layer (the first phase difference layer side of the linear polarizing layer), or may be provided on the side opposite to the viewing side of the linear polarizing layer. When the touch sensor panel is provided on the viewing side of the linear polarization layer, the touch sensor panel may constitute a high refractive index layer described later. When the touch sensor panel is provided on the side opposite to the viewing side of the linear polarization layer, the touch sensor panel is preferably provided between the linear polarization layer and the display unit.

(High refractive index layer)

The high refractive index layer is not particularly limited as long as it is a layer whose refractive index is within the range specified in this embodiment (1.60 or more). The high refractive index layer may be a front panel or a touch sensor panel of a display device as long as it is a layer having the above-mentioned refractive index. The high refractive index layer may have a single-layer structure or a multi-layer structure. When the high refractive index layer has a multilayer structure and the high refractive index layer has the above refractive index, the high refractive index layer may include a layer with a refractive index of less than 1.60.

The front panel may constitute the front surface of the display device. The front plate may be a plate-shaped body capable of transmitting light, and may be, for example, a resin plate, a resin film, a glass plate, or a glass film. The front plate may have a single-layer structure or a multi-layer structure. The refractive index of the front plate may be 1.45 or more and 1.9 or less.

The polymer constituting the resin plate or resin film is not particularly limited as long as it is a resin that can transmit light. Such polymers include, for example, triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butylcellulose, acetylpropionylcellulose, polyester, polystyrene, polyamide, polyetherimide, poly(meth)acrylic, Polyimide, polyether sulfone, polysulfone, polyethylene, polypropylene, polymethyl pentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, poly Examples include methyl (meth)acrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These polymers can be used individually or in mixture of two or more types. In this specification, (meth)acrylic refers to acrylic and/or methacrylic, and (meth)acrylate refers to acrylate and/or methacrylate.

When the front plate is a resin film, the front plate may have a hard coat layer on at least one side of the resin film. The hard coat layer is, for example, a cured layer of ultraviolet curable resin. Examples of the ultraviolet curable resin include (meth)acrylic resins such as monofunctional (meth)acrylic resins, multifunctional (meth)acrylic resins, and multifunctional (meth)acrylic resins with a dendrimer structure; silicone resin; polyester resin; Urethane resin; amide resin; Epoxy resin, etc. can be mentioned. The hard coat layer may contain additives to improve strength. The additive is not particularly limited and includes inorganic fine particles, organic fine particles, or mixtures thereof. When the resin film has hard coat layers on both surfaces, the composition and thickness of each hard coat layer may be the same or different from each other.

When the front plate is a glass plate or a glass film, tempered glass for display is preferably used.

Examples of the touch sensor panel constituting the high refractive index layer include the touch sensor panel described above. When the touch sensor panel constitutes a high refractive index layer, the refractive index of the touch sensor panel is 1.60 or more, preferably 1.70 or more, more preferably 1.90 or more, usually 2.70 or less, preferably 2.60 or less. , more preferably 2.40 or less.

(1st phase difference layer, 2nd phase difference layer, 3rd phase difference layer, 4th phase difference layer)

The first retardation layer, the second retardation layer, the third retardation layer, and the fourth retardation layer (hereinafter, they may be collectively referred to as “retardation layer”) may be a stretched film or a cured product of a polymerizable liquid crystal compound. It may also include layers.

When the retardation layer is a stretched film, a conventionally known stretched film can be used, and a resin film to which a phase difference is imparted by uniaxial stretching or biaxial stretching can be used. Resin films include cellulose films such as triacetylcellulose and diacetylcellulose, polyester films such as polyethylene terephthalate, polyethylene isophthalate, and polybutylene terephthalate, polymethyl (meth)acrylate, and polyethyl (meth)acrylate. Acrylic resin films, polycarbonate films, polyethersulfone films, polysulfone films, polyimide films, polyolefin films, polynorbornene films, etc. can be used, but are not limited to these.

When the retardation layer is a stretched film, the thickness of the retardation layer is usually 5 μm or more and 200 μm or less, preferably 10 μm or more and 80 μm or less, and more preferably 40 μm or less.

When the retardation layer includes the cured product layer, a conventionally known polymerizable liquid crystal compound can be used as the polymerizable liquid crystal compound. A polymerizable liquid crystal compound is a compound that has at least one polymerizable group and has liquid crystallinity.

The type of polymerizable liquid crystal compound is not particularly limited, and rod-shaped liquid crystal compounds, disk-shaped liquid crystal compounds, and mixtures thereof can be used. The cured layer formed by polymerizing the polymerizable liquid crystal compound exhibits a phase difference by curing the polymerizable liquid crystal compound in an appropriate direction. When the rod-shaped polymerizable liquid crystal compound is horizontally or vertically aligned with respect to the plane direction of the display device, the optical axis of the polymerizable liquid crystal compound coincides with the long axis direction of the polymerizable liquid crystal compound. When the disc-shaped polymerizable liquid crystal compound is oriented, the optical axis of the polymerizable liquid crystal compound exists in a direction perpendicular to the disc surface of the polymerizable liquid crystal compound. As a rod-shaped polymerizable liquid crystal compound, for example, those described in Japanese Patent Publication No. Hei 11-513019 (Claim 1, etc.) can be suitably used. Disk-shaped polymerizable liquid crystal compounds are described in JP-A-2007-108732 (paragraphs [0020] to [0067], etc.) and JP-A-2010-244038 (paragraphs [0013] to [0108], etc.). Those described can be suitably used.

The polymerizable group contained in the polymerizable liquid crystal compound refers to a group involved in a polymerization reaction, and is preferably a photopolymerizable group. A photopolymerizable group refers to a group that can participate in a polymerization reaction by active radicals or acids generated from a photopolymerization initiator. Polymerizable groups include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, (meth)acryloyloxy group, oxiranyl group, oxetanyl group, styryl group, allyl group, etc. I can hear it. Among them, (meth)acryloyloxy group, vinyloxy group, oxiranyl group, and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystallinity of the polymerizable liquid crystal compound may be either thermotropic liquid crystal or lyotropic liquid crystal. If thermotropic liquid crystals are classified by degree of order, they may be nematic liquid crystal or smectic liquid crystal. When two or more types of polymerizable liquid crystal compounds are used together to form a cured layer of the polymerizable liquid crystal compound, it is preferable that at least one type has two or more polymerizable groups in the molecule. In this specification, (meth)acryloyl refers to acryloyl and/or methacryloyl.

When the retardation layer includes the cured product layer, the retardation layer may include an orientation layer. The alignment layer has an orientation regulating force that orients the polymerizable liquid crystal compound in a desired direction. The alignment layer may be a vertical alignment layer in which the molecular axis of the polymerizable liquid crystal compound is vertically aligned with respect to the plane direction of the display device, or may be a horizontal alignment layer in which the molecular axis of the polymerizable liquid crystal compound is horizontally aligned with respect to the plane direction of the display device, It may be an inclined alignment layer that orients the molecular axis of the polymerizable liquid crystal compound obliquely with respect to the plane direction of the display device. When the phase difference layer includes two or more alignment layers, the alignment layers may be the same or different from each other.

The alignment layer preferably has solvent resistance that does not dissolve when the composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound is applied, etc., and has heat resistance to heat treatment for removing the solvent or aligning the polymerizable liquid crystal compound. . Examples of the orientation layer include an orientation polymer layer formed of an orientation polymer, a photo-orientation polymer layer formed of a photo-orientation polymer, and a groove orientation layer having a concavo-convex pattern or a plurality of grooves (grooves) on the layer surface.

The cured layer is polymerized by applying a composition for forming a retardation layer containing a polymerizable liquid crystal compound, a solvent, and, if necessary, various additives, onto an alignment layer to form a coating film, and solidifying (curing) this coating film. A layer of a cured liquid crystal compound can be formed. Alternatively, the composition may be applied on a base layer to form a coating film, and the cured product layer may be formed by stretching the coating film together with the base layer. In addition to the polymerizable liquid crystal compound and solvent described above, the composition may contain a polymerization initiator, a reactive additive, a leveling agent, a polymerization inhibitor, etc. Known polymerizable liquid crystal compounds, solvents, polymerization initiators, reactive additives, leveling agents, polymerization inhibitors, etc. can be appropriately used.

As the base layer, a film formed of a resin material can be used, for example, a film using a resin material described as a thermoplastic resin used to form the first protective film described later. The thickness of the base material layer is not particularly limited, but generally, from the viewpoint of workability such as strength and handleability, it is preferably 1 to 300 ㎛, more preferably 20 to 200 ㎛, and even more preferably 30 to 120 ㎛. do. The base material layer may be built into the display device together with the cured layer of the polymerizable liquid crystal compound, or the base layer may be peeled off and only the cured layer of the polymerizable liquid crystal compound, or the cured layer and the alignment layer, may be inserted into the display device. It can be built-in as well. When the base material layer is built into the display device together with the cured material layer of the polymerizable liquid crystal compound, the thickness of the base layer may be less than 30 μm, for example, 25 μm or less.

When the retardation layer includes the cured product layer, the thickness of the retardation layer is preferably 0.1 ㎛ or more, more preferably 0.2 ㎛ or more, further preferably 3 ㎛ or less, and more preferably It is 2 ㎛ or less.

(Linear polarizing layer)

When unpolarized light is incident on the linearly polarized layer, it has the property of transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis. The linear polarizing layer may be a polyvinyl alcohol-based resin film (hereinafter sometimes referred to as “PVA-based film”) in which iodine is adsorbed and oriented, and a composition containing a compound having absorption anisotropy and liquid crystallinity may be used as a base film. It may be a film containing a liquid crystalline polarizing layer formed by coating. The compound having absorption anisotropy and liquid crystallinity may be a mixture of a dye having absorption anisotropy and a compound having liquid crystallinity, or may be a dye having absorption anisotropy and liquid crystallinity.

The linear polarizing layer is preferably a PVA-based film in which iodine is oriented for adsorption. The linear polarizing layer, which is a PVA-based film, is made by dyeing with iodine and stretching a PVA-based film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer-based partially saponified film. Things that have happened can be mentioned. If necessary, the PVA-based film in which iodine has been adsorbed and oriented through dyeing treatment may be treated with an aqueous boric acid solution, and then a washing step of washing off the aqueous boric acid solution may be performed. Known methods can be adopted for each process.

Polyvinyl alcohol-based resin (hereinafter sometimes referred to as “PVA-based resin”) can be produced by saponifying polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate. Other monomers that can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of PVA-based resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. The PVA-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of PVA-based resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000. The saponification degree and average polymerization degree of PVA-based resin can be determined based on JIS K 6726 (1994). If the average degree of polymerization is less than 1000, it is difficult to obtain desirable polarization performance, and if the average degree of polymerization is more than 10000, film processability may be poor.

The method for producing a linear polarizing layer that is a PVA-based film is to prepare a base film, apply a solution of a resin such as PVA-based resin on the base film, and perform drying to remove the solvent, etc. to form a resin layer on the base film. It may also include the process of doing so. Additionally, a primer layer can be formed in advance on the surface of the base film where the resin layer is formed. As the base film, a film using a resin material described as a thermoplastic resin used to form the first protective film described later can be used. Examples of the material of the primer layer include a resin obtained by crosslinking a hydrophilic resin used in the linear polarizing layer.

Subsequently, the amount of solvent such as moisture in the resin layer is adjusted as necessary, and then the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with iodine to adsorb and orient the iodine to the resin layer. Next, if necessary, the resin layer in which the iodine is adsorbed and oriented is treated with an aqueous boric acid solution, and thereafter, a washing step is performed to wash away the aqueous boric acid solution. As a result, a PVA-based film that becomes a resin layer in which iodine is adsorbed and oriented, that is, a linear polarizing layer, is manufactured. Known methods can be adopted for each process.

The amount of boric acid in the aqueous solution containing boric acid for treating the PVA-based film or resin layer with iodine adsorption orientation is usually about 2 to 15 parts by mass per 100 parts by mass of water, and is preferably 5 to 12 parts by mass. This boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by mass per 100 parts by mass of water, and is preferably about 5 to 12 parts by mass. The immersion time in the aqueous solution containing boric acid is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

Uniaxial stretching of the PVA-based film, base film, and resin layer may be carried out before dyeing, may be carried out during dyeing, may be carried out during boric acid treatment after dyeing, or uniaxial stretching may be carried out in each of these plural steps. The PVA-based film, base film, and resin layer may be uniaxially stretched in the MD direction (film transport direction). In this case, they may be uniaxially stretched between rolls with different peripheral speeds, or uniaxially stretched using a heat roll. It's also good. Additionally, the PVA-based film, base film, and resin layer may be uniaxially stretched in the TD direction (direction perpendicular to the film transport direction), and in this case, the so-called tenter method can be used. In addition, the stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state in which the PVA-based film or resin layer is swollen with a solvent. In order to demonstrate the performance of the linear polarizing layer, the draw ratio is preferably 4 times or more, preferably 5 times or more, and especially 5.5 times or more. There is no particular upper limit to the stretch ratio, but from the viewpoint of suppressing breakage, etc., 8 times or less is preferable.

A linear polarizing layer produced by a manufacturing method using a base film can be obtained by laminating the first protective film or the second protective film and then peeling the base film. According to this method, additional thinning of the linear polarization layer becomes possible.

The thickness of the linear polarizing layer, which is a PVA-based film, is preferably 1 μm or more, may be 2 μm or more, may be 5 μm or more, and is preferably 30 μm or less, more preferably 15 μm or less, and may be 10 μm or less. It is good, and it can be 8 ㎛ or less.

The film containing the liquid crystalline polarizing layer includes a linear polarizing layer obtained by applying a composition containing a dye having liquid crystallinity and absorption anisotropy, or a composition containing a dye having absorption anisotropy and a polymerizable liquid crystal to a base film. there is. Examples of the base film include films using a resin material described as a thermoplastic resin used to form the first protective film described later. Examples of films containing a liquid crystalline polarizing layer include the polarizing layer described in Japanese Patent Application Laid-Open No. 2013-33249 and the like.

The total thickness of the base film and the linear polarizing layer formed as described above is preferably smaller, but if it is too small, the strength tends to decrease and processability tends to be poor, so it is usually 20 ㎛ or less, and is preferably 5 It is ㎛ or less, and more preferably 0.5 to 3 ㎛.

The linear polarizing layer (PVA-based film, film containing a liquid crystalline polarizing layer) obtained as described above is laminated with a first protective film and/or a second protective film described later through an adhesive on one or both sides thereof. It may be built into a display device as a linear polarizer. As a film containing a liquid crystalline polarizing layer, the above-mentioned base film may be used as a first protective film or a second protective film.

(1st protective film, 2nd protective film)

As the first protective film and the second protective film, for example, a film formed of a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier, isotropy, stretchability, etc. is used. Specific examples of thermoplastic resins include cellulose resins such as triacetylcellulose; Polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resin; polysulfone resin; polycarbonate resin; Polyamide resins such as nylon and aromatic polyamide; polyimide resin; Polyolefin resins such as polyethylene, polypropylene, and ethylene/propylene copolymer; Cyclic polyolefin resins having cyclo-based and norbornene structures (also referred to as norbornene-based resins); (meth)acrylic resin; polyarylate resin; polystyrene resin; Polyvinyl alcohol resin and mixtures thereof can be mentioned. The resin compositions of the first protective film and the second protective film may be the same or different.

The first protective film may have anti-reflection properties, anti-glare properties, hard coat properties, etc. (hereinafter, the protective film having the above properties may be referred to as a “functional protective film”). When the first protective film is not a functional protective film, a surface functional layer such as an anti-reflection layer, an anti-glare layer, or a hard coat layer may be provided on one side of the linear polarizing plate. The surface functional layer is preferably provided so as to directly contact the first protective film. The surface functional layer is preferably provided on the side opposite to the linear polarizing layer side of the first protective film.

The first protective film and the second protective film are each independently preferably 3 μm or larger, more preferably 5 μm or larger, more preferably 50 μm or smaller, and more preferably 30 μm or smaller.

(1st bonding layer, 2nd bonding layer, 3rd bonding layer, 4th bonding layer, 5th bonding layer, 6th bonding layer)

The first bonding layer, the second bonding layer, the third bonding layer, the fourth bonding layer, the fifth bonding layer, the sixth bonding layer, and the bonding layer (hereinafter, these may be collectively referred to as the “bonding layer”). , each independently, is a pressure-sensitive adhesive layer or an adhesive layer.

When the bonding layer is an adhesive layer, it is an adhesive layer formed using an adhesive composition. The adhesive composition or the reaction product of the adhesive composition exhibits adhesiveness by attaching itself to an adherend such as a metal layer, and is called a so-called pressure-sensitive adhesive. In addition, the degree of crosslinking and adhesion of the adhesive layer formed using the active energy ray-curable adhesive composition described later can be adjusted by irradiating active energy rays.

As the adhesive composition, conventionally known adhesives with excellent optical transparency can be used without particular restrictions, and for example, adhesive compositions containing base polymers such as acrylic polymer, urethane polymer, silicone polymer, and polyvinyl ether can be used. Additionally, the adhesive composition may be an active energy ray-curable adhesive composition, a thermosetting adhesive composition, or the like. Among these, an adhesive composition using an acrylic resin as a base polymer, which is excellent in transparency, adhesiveness, re-peelability (reworkability), weather resistance, heat resistance, etc., is suitable. The adhesive layer is preferably comprised of a reaction product of an adhesive composition containing a (meth)acrylic resin, a crosslinking agent, and a silane compound, and may contain other components.

The adhesive layer may be formed using an active energy ray-curable adhesive. The active energy ray-curable adhesive can form a harder adhesive layer by mixing an ultraviolet curable compound such as a multifunctional acrylate with the adhesive composition described above, forming an adhesive layer, and then curing the adhesive by irradiating ultraviolet rays. Active energy ray-curable adhesives have the property of curing when irradiated with energy rays such as ultraviolet rays or electron beams. Since the active energy ray-curable adhesive has adhesiveness even before energy ray irradiation, it adheres closely to the adherend and has the property of adjusting the adhesion by curing by irradiation of energy ray.

The thickness of the adhesive layer is not particularly limited, but is preferably 5 μm or more, may be 10 μm or more, may be 15 μm or more, may be 20 μm or more, may be 25 μm or more, and is usually 300 μm or less, and may be 250 μm or more. It may be less than 100 μm, or less than 50 μm.

When the bonding layer is an adhesive layer, the adhesive layer can be formed by curing the curable component in the adhesive composition. As an adhesive composition for forming an adhesive layer, adhesives other than pressure-sensitive adhesives (adhesives) include, for example, water-based adhesives and active energy ray-curable adhesives.

Examples of water-based adhesives include adhesives in which polyvinyl alcohol resin is dissolved or dispersed in water. The drying method when using a water-based adhesive is not particularly limited, but for example, a drying method using a hot air dryer or an infrared dryer can be adopted.

Examples of the active energy ray-curable adhesive include a non-solvent type active energy ray-curable adhesive containing a curable compound that hardens by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. By using a solvent-free active energy ray-curable adhesive, the adhesion between layers can be improved.

The active energy ray-curable adhesive preferably contains one or both of a cationically polymerizable curable compound and a radically polymerizable curable compound in that it exhibits good adhesiveness. The active energy ray-curable adhesive may further include a cationic polymerization initiator such as a photocationic polymerization initiator or a radical polymerization initiator to initiate the curing reaction of the curable compound.

Cationic polymerizable curable compounds include, for example, alicyclic epoxy compounds having an epoxy group bonded to an alicyclic ring, polyfunctional aliphatic epoxy compounds having two or more epoxy groups and no aromatic ring, and monofunctional epoxy groups having one epoxy group (however, alicyclic (excluding those included in the formula epoxy compounds), epoxy-based compounds such as polyfunctional aromatic epoxy compounds having two or more epoxy groups and having an aromatic ring; Oxetane compounds having one or two or more oxetane rings in the molecule; A combination of these can be mentioned.

Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or two or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having radically polymerizable double bonds, or these. There can be combinations.

The active energy ray-curable adhesive may contain a sensitizer such as a photosensitizer if necessary. By using a sensitizer, reactivity can be improved and the mechanical strength and adhesive strength of the adhesive layer can be further improved. As a sensitizer, a known one can be appropriately applied. When blending a sensitizer, the blending amount is preferably in the range of 0.1 to 20 parts by mass based on 100 parts by mass of the total amount of the active energy ray-curable adhesive.

The active energy ray-curable adhesive may, if necessary, contain additives such as ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, antifoaming agents, antistatic agents, leveling agents, and solvents. You can.

When an active energy ray-curable adhesive is used, the adhesive layer can be formed by curing the applied layer of the adhesive by irradiating active energy rays such as ultraviolet rays, visible light, electron beams, or X-rays. As an active energy ray, ultraviolet rays are preferable, and as a light source in this case, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a metal halide lamp, etc. can be used.

When the bonding layer is an adhesive layer, the thickness is preferably 0.1 μm or more, may be 0.5 μm or more, and is preferably 10 μm or less, and may be 5 μm or less.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[Measurement of refractive index]

The refractive index of the high refractive index layer was measured using a multi-wavelength Abbe refractometer (“DR-M4” manufactured by Atago Co., Ltd.) in an environment of 25°C, with the measurement wavelength set to 589 nm.

[Measurement of visibility correction single transmittance Ty]

For the linearly polarized layer, the MD transmittance and TD transmittance in the wavelength range of 380 to 780 nm were measured using a spectrophotometer with an integrating sphere (“V7100” manufactured by Nippon Bunko Co., Ltd.), using the following formula:

Group transmittance (%)=(MD+TD)/2

Based on this, the single transmittance at each wavelength was calculated.

“MD transmittance” is the transmittance when the direction of polarization coming from the Glenn Thompson prism is parallel to the transmission axis of the linearly polarized layer, and is expressed as “MD” in the above formula. In addition, “TD transmittance” is the transmittance when the direction of polarized light coming from the Glenn Thompson prism and the transmission axis of the linearly polarized layer are orthogonal, and is expressed as “TD” in the above formula. For the obtained single transmittance, visibility correction was performed using a 2-degree field of view (C _light source) according to JIS Z 8701: 1999 "Color _display method - _XYZ colorimetric system and .

[Measurement of in-plane phase difference value]

The in-plane retardation values of the first retardation layer and the first protective film were measured using a retardation measurement device (KOBRA-WPR, manufactured by Ojigeisokugiki Co., Ltd.).

[Measurement of thickness direction phase difference value]

The thickness direction retardation value of the second retardation layer was measured using a retardation measurement device (KOBRA-WPR, manufactured by Ojigeisokugiki Co., Ltd.). In the measurement, the incident angle of light to the second phase contrast layer was changed, and the front phase difference value of the second phase difference layer and the phase difference value when tilted at 40° around the fast axis were measured. The average refractive index at each wavelength was measured using an ellipsometer M-220 manufactured by Nippon Bunko Co., Ltd. In addition, the thickness of the second phase contrast layer was measured using an Optical NanoGauge film thickness gauge C12562-01 manufactured by Hamamatsu Hotonix Co., Ltd. From the front phase difference value measured above, the phase difference value when tilted 40° around the true axis, the average refractive index, and the thickness of the second phase difference layer, Oji Keisokugiki technical data (https://oji-keisoku.co The 3D refractive index was calculated by referring to .jp/cms/uploads/kbr_shiryo04.pdf). From the obtained three-dimensional refractive index, the thickness direction retardation value Rth of the second retardation layer was calculated according to the above equation (i).

[Measurement of stimulus value Y]

To measure the stimulation value Y, a spectrophotometer (CM2600d manufactured by Konica Minolta) was used. Light from the spectrophotometer was incident from the moss eye film side of the laminate, and the stimulation value Y of the reflected light was measured. Additionally, because the reflectance of the moss eye film is very small, the effect of spectrophotometric light reflecting at the interface between the air and the moss eye film can be ignored. In the measurement, it was confirmed that there was no light-reflecting object within 1 m in the light propagation direction from the light receiving unit of the spectrophotometer, and the measurement was performed in a sufficiently dark environment to exclude the influence of external light. As a result of measuring the spectrophotometer in this measurement environment without a measurement sample (laminated body), it was confirmed that the stimulation value Y was 0.1% or less. Therefore, when the magnetic pole value Y of the laminate is measured under the above measurement environment, the light detected by the spectrophotometer is partially absorbed by the polarizer and becomes only the light reflected by the high refractive index layer.

[Example 1]

(Production of polarizer (1))

A polyvinyl alcohol-based resin film with a thickness of 20 μm (average degree of polymerization is about 2400, saponification degree is more than 99.9 mol%) was vertically uniaxially stretched at a stretching ratio of about 4.5 by dry stretching. While maintaining the tension after stretching, it was immersed in pure water at a temperature of 30°C for 60 seconds. While maintaining the tension, it was immersed in an iodine/potassium iodide aqueous solution with a mass ratio of iodine/potassium iodide/water of 0.05/5/100 and a temperature of 28°C for 60 seconds. While maintaining the tension, the mass ratio of potassium iodide/boric acid/water was 15/5.5/100 and the sample was immersed in an aqueous solution of potassium iodide/boric acid at a temperature of 64°C for 170 seconds. While maintaining the tension, it was washed with pure water at a temperature of 10°C for 5 seconds, and then dried in the air at a temperature of 80°C for 70 seconds while maintaining the tension, so that the iodine was adsorbed onto the polyvinyl alcohol-based resin film. and a polarizer (1) (linear polarization layer) with a thickness of 8 μm was produced. The visibility corrected single transmittance Ty of this polarizer (1) was 42.2 ± 0.5%.

(Preparation of the first phase contrast layer (1))

As the first retardation layer 1, a cyclic polyolefin resin film with a hard coat layer and a thickness of 25 μm was prepared. The in-plane retardation value of the first retardation layer 1 at a wavelength of 550 nm was 100 nm.

(Preparation of water-based adhesive)

Dissolve 3 parts by mass of carboxyl group-modified polyvinyl alcohol (“KL-318” manufactured by Kuraray Co., Ltd.) in 100 parts by mass of water to obtain an aqueous polyvinyl alcohol solution, and add water-soluble poly to this aqueous polyvinyl alcohol solution (100 parts by mass of water). 1.5 parts by mass (solid content is 0.45 parts by mass) of amide epoxy resin [“Sumirez Resin 650 (30)” manufactured by Taoka Chemical Co., Ltd., solid content concentration 30% by mass] was added to obtain a water-based adhesive.

(Production of linear polarizer (1))

As a first protective film, a cyclic polyolefin resin film with a thickness of 13 μm was prepared. Additionally, as a second protective film, a triacetylcellulose-based resin film (“KC4UY” manufactured by Konica Minolta Co., Ltd., thickness 40 μm) whose surface was not subjected to saponification treatment was prepared.

The first protective film (cyclic polyolefin resin film) prepared above is polymerized on one side of the polarizer (1) obtained above through the water-based adhesive obtained above, and pure water is applied to the other side of the polarizer (1). The water-based adhesive is cured by polymerizing the second protective film (triacetylcellulis-based resin film) prepared above, passing it between a pair of bonding rolls, and then heating and drying at a temperature of 85° C. for 3 minutes. 3 An adhesive layer as a bonding layer was formed to produce a linear polarizing plate (1) having a layer structure of first protective film/third bonding layer/polarizer (1)/second protective film. The in-plane retardation value of the first protective film at a wavelength of 550 nm was 0 nm.

(Production of high refractive index layer)

ITO (Indium Tin Oxide), a mixture of indium oxide and tin oxide, is deposited on one side of an alkali-free glass plate (“Eagle , a high refractive index layer, which is a laminated structure of an alkali-free glass plate and an ITO layer, was obtained. The refractive index of this high refractive index layer was measured from the ITO layer side and was 2.00.

(Production of Laminate (1))

Next, the second protective film is peeled from the linear polarizer 1, and a moss eye film (manufactured by Geomatech) is applied to the exposed polarizer 1 side through a fourth bonding layer (acrylic adhesive layer with a thickness of 25 μm). g.moth) is laminated on the first protective film side of the linear polarizing plate (1), a second bonding layer (acrylic adhesive layer with a thickness of 5 μm), a first phase difference layer (1), and a first bonding layer (thickness of 25 μm). ㎛ acrylic adhesive layer), a laminated structure of an alkali-free glass plate with a refractive index of 1.50 (Eagle ) was produced. The laminate (1) was laminated so that the high refractive index layer was on the black acrylic plate side. The space between the high refractive index layer and the black acrylic plate was filled with ethanol dropped before lamination to exclude an air layer. The first retardation layer 1 was laminated so that the hard coat layer side was on the high refractive index layer side. In the laminate (1), the angle formed between the slow axis of the first retardation layer (1) and the absorption axis of the polarizer (1) of the linear polarizer (1) was 45°. The layer structure of the obtained laminate (1) is black acrylic plate/ethanol/high refractive index layer/first bonding layer/first phase difference layer (1)/second bonding layer/first protective film/third bonding layer/polarizer. (1)/Fourth laminate layer/Moss eye film. The results of measuring the stimulation value Y of the laminate (1) are shown in Table 1. The moss eye film is provided to enable evaluation of the laminate 1 while ignoring the influence of interface reflection between the fourth bonding layer and the air layer, and in an actual display device, it is different from the polarizer 1 of the fourth bonding layer. A display unit is disposed on the opposite side.

[Example 2]

(Preparation of the first phase contrast layer (2))

As the first retardation layer (2), a cyclic polyolefin resin film with a thickness of 50 μm was prepared. The in-plane retardation value of the first retardation layer 2 at a wavelength of 550 nm was 141 nm.

(Production of laminate (2))

A laminate (2) was obtained in the same manner as in Example 1, except that the first retardation layer (2) was used instead of the first retardation layer (1). The layer structure of the obtained laminate (2) is black acrylic plate/ethanol/high refractive index layer/first bonding layer/first phase difference layer (2)/second bonding layer/first protective film/third bonding layer/polarizer. (1)/Fourth laminate layer/Moss eye film. The results of measuring the stimulation value Y of the laminate (2) are shown in Table 1.

[Example 3]

(Preparation of composition for forming horizontal alignment film)

A composition for forming a horizontal alignment film was prepared by mixing 5 parts by mass of a photo-alignment polymer having the following structure (described in Japanese Patent Application Laid-Open No. 2013-33249) with 95 parts by mass of cyclopentanone (solvent) and stirring for 1 hour at a temperature of 80°C. got it

・Photo-alignment polymer (5 parts by mass):

· Solvent (95 parts by mass): Cyclopentanone

(Preparation of polymerizable liquid crystal composition (A1) for forming the first retardation layer (3))

Polymerizable liquid crystal compound (X1) and polymerizable liquid crystal compound (X2) were mixed at a mass ratio of 90:10 to obtain a mixture. Based on 100 parts of the resulting mixture, 0.1 part of the leveling agent "BYK-361N" (manufactured by BM Chemie) and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1- as a photopolymerization initiator. 6 parts of On (“Igacure (registered trademark) 369 (Irg 369)” manufactured by BASF Japan Co., Ltd.) was added. Additionally, N-methyl-2-pyrrolidone (NMP) was added so that the solid concentration was 13%. By stirring this mixture at 80°C for 1 hour, polymerizable liquid crystal composition (A1) for forming the first phase difference layer (3) was obtained.

Polymerizable liquid crystal compound (X1):

Polymerizable liquid crystal compound (X2):

(Production of the first phase difference layer (3))

After corona treatment was performed on a COP (cyclic olefin resin) film (ZF-14-50) manufactured by Nippon Zeon Co., Ltd., the composition for forming a horizontal alignment film obtained above was applied using a bar coater and applied at 80° C. for 1 minute. After drying, polarization UV exposure was performed using a polarization UV irradiation device (SPOT CURE SP-9; manufactured by Ushio Denki Co., Ltd.) at an integrated light amount of 100 mJ/cm2 at a wavelength of 313 nm to obtain a horizontal alignment film. . The film thickness of the obtained horizontal alignment film was measured with an ellipsometer and was 200 nm.

Subsequently, the polymerizable liquid crystal composition (A1) obtained above was applied onto the horizontal alignment film using a bar coater, heated at 120°C for 60 seconds, and then heated with a high-pressure mercury lamp (Unicure VB-15201BY-A, Ushio Denki Co., Ltd.). By irradiating ultraviolet rays (accumulated amount of light at a wavelength of 365 nm under a nitrogen atmosphere: 500 mJ/cm2) from the surface to which the polymerizable liquid crystal composition (A1) was applied using a liquid crystal composition (manufactured by Geisha), a horizontally aligned liquid crystal layer (polymerizable) was formed. A cured product layer of a liquid crystal compound) was formed, and a laminated structure (A1) having a layer structure of COP film/horizontal alignment film/horizontal alignment liquid crystal layer was obtained. After confirming that there is no retardation in the COP film, the in-plane retardation values Re (450) and Re (550) at a wavelength of 450 nm and 550 nm of the laminated structure (A1) are calculated as the in-plane retardation of the first retardation layer (3). Measured as values Re(450) and Re(550), Re(550) was 139 nm. When Re(450)/Re(550) was calculated and found to be 0.87, it was confirmed that this laminate exhibits reverse wavelength dispersion.

The COP film of the laminated structure (A1) was peeled off, and the horizontal alignment film/horizontal alignment liquid crystal layer was used as the first retardation layer (3).

(Production of laminate (3))

A laminate (3) was obtained in the same manner as in Example 1, except that the first retardation layer (3) was used instead of the first retardation layer (1). The first retardation layer 3 was laminated so that the horizontal alignment film side was on the high refractive index layer side. The layer structure of the obtained laminate (3) is black acrylic plate/ethanol/high refractive index layer/first bonding layer/first phase difference layer (3)/second bonding layer/first protective film/third bonding layer/polarizer. (1)/Fourth laminate layer/Moss eye film. The results of measuring the stimulation value Y of the laminate (3) are shown in Table 1.

[Example 4]

(Preparation of composition for forming vertical alignment film)

Silane coupling agent "KBE-9103" (manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in a mixed solvent containing ethanol and water in a ratio of 9:1 (weight ratio) to form a vertically aligned film with a solid content concentration of 1%. A composition was obtained.

(Preparation of polymerizable liquid crystal composition (A2) for forming second phase contrast layer (1))

For 100 parts of Paliocolor LC242 (registered trademark of BASF Corporation), which is a polymerizable liquid crystal compound, 0.1 part of F-556 as a leveling agent and 3 parts of Igacure 369 as a polymerization initiator were added. Cyclopentanone was added so that the solid content concentration was 13%, and polymerizable liquid crystal composition (A2) was obtained.

(Production of the second phase difference layer (1))

After corona treatment was performed on a COP (cyclic olefin resin) film (ZF-14-50) manufactured by Nippon Zeon Co., Ltd., the composition for forming a vertical alignment film was applied using a bar coater, dried at 120°C for 1 minute, and An alignment film was obtained. The film thickness of the obtained vertically aligned film was measured with an ellipsometer and was 100 nm.

Subsequently, the polymerizable liquid crystal composition (A2) obtained above was applied onto the vertical alignment film using a bar coater, dried at 120°C for 1 minute, and then quenched with a high-pressure mercury lamp (Unicure VB-15201BY-A, Ushio Denki Co., Ltd.) By irradiating ultraviolet rays from the side on which the polymerizable liquid crystal composition (A2) was applied (accumulated amount of light at a wavelength of 365 nm in a nitrogen atmosphere: 500 mJ/cm2) using a product manufactured by Geisha, a vertically aligned liquid crystal layer (polymerizable liquid crystal composition) was formed. A layer of a cured liquid crystal compound) was formed to obtain a laminated structure (A2) having a layer structure of COP film/vertically aligned film/vertically aligned liquid crystal layer. After confirming that there is no phase difference in the COP film, the thickness direction retardation value Rth (550) at a wavelength of 550 nm of the laminated structure (A2) is measured as the thickness direction retardation value Rth (550) of the second phase difference layer (1). As a result, Rth(550) was -70 nm.

The COP film and vertical alignment film of the laminated structure (A2) were peeled off, and the vertical alignment liquid crystal layer was used as the second retardation layer (1).

(Production of laminate (4))

The horizontally aligned liquid crystal layer side of the first retardation layer 3 and the second retardation layer 1, produced in the same order as in Example 3, are bonded together using an ultraviolet curing adhesive, and the ultraviolet curing adhesive is cured to form a sixth bond. An adhesive layer (thickness of 1 μm) was formed as a laminate to produce a retardation laminate of the second retardation layer (1)/sixth laminate layer/first retardation layer (3).

A laminate (4) was obtained in the same manner as in Example 1, except that a retardation laminate was used instead of the first retardation layer (1). The retardation laminate was laminated so that the second retardation layer (1) side was the high refractive index layer (1) side. The layer structure of the obtained laminate (4) is black acrylic plate/ethanol/high refractive index layer/first bonded layer/second retardation layer (1)/sixth bonded layer/first phase contrast layer (3)/second bonded layer. It was a laminate/first protective film/third laminate layer/polarizer (1)/fourth laminate layer/moss eye film. The results of measuring the stimulation value Y of the laminate (4) are shown in Table 1.

[Example 5]

(Production of polarizer (2))

A polyvinyl alcohol-based resin film with a thickness of 20 μm (average degree of polymerization is 2400 and degree of saponification is 99.9 mol% or more) was vertically uniaxially stretched at a stretching ratio of about 4.5 by dry stretching. While maintaining the tension after stretching, it was immersed in pure water at a temperature of 30°C for 60 seconds. While maintaining the tension, it was immersed in an iodine/potassium iodide aqueous solution with a mass ratio of iodine/potassium iodide/water of 0.02/5/100 and a temperature of 28°C for 60 seconds. While maintaining the tension, the mass ratio of potassium iodide/boric acid/water was 15/5.5/100 and the sample was immersed in an aqueous solution of potassium iodide/boric acid at a temperature of 64°C for 45 seconds. While maintaining the tension, it was washed with pure water at a temperature of 10°C for 5 seconds, and then dried in the air for 75 seconds at a temperature of 80°C while maintaining the tension, so that the iodine was adsorbed onto the polyvinyl alcohol-based resin film. and a polarizer (2) (linear polarization layer) with a thickness of 8 μm was produced. The visibility corrected single transmittance Ty of this polarizer (2) was 46.0±0.5%.

(Production of laminate (5))

Laminate (5) was obtained in the same manner as in Example 1, except that polarizer (2) was used instead of polarizer (1). The layer structure of the obtained laminate (5) is black acrylic plate/ethanol/high refractive index layer/first bonding layer/first phase difference layer (1)/second bonding layer/first protective film/third bonding layer/polarizer. (2)/Fourth bonding layer/Moss eye film. The results of measuring the stimulation value Y of the laminate (5) are shown in Table 2.

[Example 6]

Laminate (6) was obtained in the same manner as in Example 2, except that polarizer (2) was used instead of polarizer (1). The layer structure of the obtained laminate (6) is black acrylic plate/ethanol/high refractive index layer/1st bonding layer/1st retardation layer (2)/2nd bonding layer/1st protective film/3rd bonding layer/polarizer. (2)/Fourth bonding layer/Moss eye film. The results of measuring the stimulation value Y of the laminate (6) are shown in Table 2.

[Example 7]

Laminate (7) was obtained in the same manner as in Example 3, except that polarizer (2) was used instead of polarizer (1). The layer structure of the obtained laminate (7) is black acrylic plate/ethanol/high refractive index layer/first bonding layer/first phase difference layer (3)/second bonding layer/first protective film/third bonding layer/polarizer. (2)/Fourth bonding layer/Moss eye film. The results of measuring the stimulation value Y of the laminate (7) are shown in Figure 2.

[Example 8]

Laminate (8) was obtained in the same manner as in Example 4, except that polarizer (2) was used instead of polarizer (1). The layer structure of the obtained laminate (8) is black acrylic plate/ethanol/high refractive index layer/first bonded layer/second retardation layer (1)/sixth bonded layer/first phase contrast layer (3)/second bonded layer. It was a laminate/first protective film/third laminate layer/polarizer (2)/fourth laminate layer/moss eye film. The results of measuring the stimulation value Y of the laminate (8) are shown in Figure 2.

[Comparative Example 1]

A laminate (9) was produced in the same manner as in Example 5, except that the first retardation layer (1) and the second bonding layer were not laminated, and the high refractive index layer was laminated on the first protective film through the first adhesive layer. got it The layer structure of the obtained laminate (9) was black acrylic plate/ethanol/high refractive index layer/first bonding layer/first protective film/third bonding layer/polarizer (2)/fourth bonding layer/moss eye film. . The results of measuring the stimulation value Y of the laminate (9) are shown in Figure 2.

From the results shown in Tables 1 and 2, if the in-plane phase difference value of the first phase difference layer is in the range of 80 nm to 170 nm, the stimulation value Y becomes small, and the reflected light incident on the light receiving element of the display unit can be reduced. I knew it was there. In addition, it was found that even when the visibility correction single transmittance Ty of the polarizer included in the laminate is large, the magnetic pole value Y can be made small, and the reflected light incident on the light receiving element of the display unit can be reduced.

1 to 4: Display device
11: Linear polarization layer
12: first protective film
13: Third phase difference layer
21: first bonding layer
22: Second bonding layer
23: Third bonding layer
24: Fourth bonding layer
25: Fifth bonding layer
26: 6th bonding layer
31: first phase contrast layer
32: second phase contrast layer
40: display unit
41: display element
42: Light receiving sensor
45: High refractive index layer
51 to 54: Optical laminate.

Claims (19)

A display device having a high refractive index layer, a first phase difference layer, a linear polarization layer, and a display unit in this order from the viewer side,
The refractive index of the high refractive index layer is 1.60 or more,
The display unit has a display element and a light receiving sensor,
The first phase contrast layer and the linear polarization layer are stacked to cover the display element and the light receiving sensor. The display device according to claim 1, wherein the first retardation layer covers the entire surface on the viewing side of the linear polarization layer when viewed in plan. The display device according to claim 1 or 2, wherein the linear polarization layer has a visibility-corrected single transmittance of 42% or more. The display device according to claim 1 or 2, wherein the angle between the slow axis of the first retardation layer and the absorption axis of the linear polarization layer is 10° or more and 80° or less. The display device according to claim 1 or 2, wherein the in-plane retardation value of the first retardation layer at a wavelength of 550 nm is 80 nm or more and 170 nm or less. The display device of claim 5, wherein the first phase difference layer has reverse wavelength dispersion. The method of claim 5, further comprising a second retardation layer between the high refractive index layer and the linear polarization layer,
The second phase difference layer is laminated to cover the display element and the light receiving sensor,
A display device in which the thickness direction retardation value of the second retardation layer at a wavelength of 550 nm is -140 nm or more and -20 nm or less. The display device according to claim 1 or 2, wherein the stimulus value Y of the reflected light when the light emitted from the display element is reflected by the high refractive index layer is 3.45% or more and 4.54% or less. The display device according to claim 1 or 2, wherein the light receiving sensor is capable of detecting light with a wavelength of 320 nm or more and 4000 nm or less. The display device according to claim 1 or 2, wherein the light emitted from the display element has a wavelength of 320 nm or more and 4000 nm or less. The display device according to claim 1 or 2, further comprising a third retardation layer between the linear polarization layer and the display unit. An optical laminate having a high refractive index layer, a first phase difference layer, and a linear polarization layer in this order,
An optical laminate wherein the high refractive index layer has a refractive index of 1.60 or more. The optical laminate according to claim 12, wherein the first retardation layer covers the entire surface on the viewing side of the linear polarization layer when viewed in plan. The optical laminate according to claim 12 or 13, wherein the linear polarization layer has a visibility-corrected single transmittance of 42% or more. The optical laminate according to claim 12 or 13, wherein the angle between the slow axis of the first retardation layer and the absorption axis of the linear polarization layer is 10° or more and 80° or less. The optical laminate according to claim 12 or 13, wherein the in-plane retardation value of the first retardation layer at a wavelength of 550 nm is 80 nm or more and 170 nm or less. The optical laminate according to claim 12 or 13, wherein the first phase difference layer has reverse wavelength dispersion. The method of claim 12 or 13, further comprising a second retardation layer between the high refractive index layer and the linear polarization layer,
An optical laminate wherein the thickness direction retardation value of the second retardation layer at a wavelength of 550 nm is -140 nm or more and -20 nm or less. The optical laminate according to claim 12 or 13, further comprising a third retardation layer on a side of the linear polarization layer opposite to the first retardation layer.