JP2020034858A - Display panel, image display device, and method for selecting ultraviolet absorption layer for display panel - Google Patents

Abstract

To provide a display panel that can substantially reduce photo-degradation over time of a phase difference layer and can prevent a reduction over time of display quality.SOLUTION: A display panel has a display element (A), a phase difference layer (B) arranged on a light emitting surface of the display element, and an ultraviolet absorption layer (C) arranged on the light emitting layer of the phase difference layer. A transmission start wavelength aof the phase difference layer (B) based on a spectral transmission spectrum of linearly polarized light, a transmission start wavelength aof the phase difference layer (B) based on a spectral transmission spectrum of linearly polarized light, and a transmission start wavelength aof the ultraviolet absorption layer (C) based on a spectral transmission spectrum of unpolarized light, satisfy a specific relationship.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a display panel, an image display device, and a method for selecting an ultraviolet absorbing layer of a display panel.

  As an optical film applied to an image display device or the like, there is a retardation film that imparts a desired retardation to incident light. For example, in an organic electroluminescence (organic EL) display device, a circularly polarizing plate formed by combining a λ / 4 retardation film and a linearly polarizing plate is used to prevent external light reflection. Further, in a liquid crystal display device of an IPS mode or the like, a retardation film in which a positive A plate and a positive C plate are combined is used as a part of an optical compensation film in order to increase a contrast in a field of view from an oblique direction. .

  However, general-purpose retardation films have a wavelength dependence of retardation (positive dispersion of retardation) such that the retardation measured at a long wavelength is smaller than the retardation measured at a short wavelength. There is a problem that the image cannot be displayed and the color becomes bluish purple, and the display quality of the image display device is reduced.

As a method for solving the above problem, for example, a method of laminating a λ / 4 retardation film and a λ / 2 retardation film has been proposed.
In this method, for a wide wavelength region, it is possible to compensate for the color in the front direction, but productivity is poor because a step of bonding two retardation films at a specific angle is required, and However, there is a problem that the cost increases because the number of members increases.

Further, as another method for solving the above problem, Patent Document 1 proposes a retardation film made of a specific aromatic polycarbonate.
However, since the retardation film of Patent Document 1 has a small in-plane birefringence, it is necessary to increase the thickness of the film in order to function as a λ / 4 retardation film, which hinders the thinning of the image display device. There is a problem of coming.

  Therefore, a retardation film using a liquid crystal compound having reverse dispersion characteristics as disclosed in Patent Documents 2 to 4 has been proposed. The inverse dispersion characteristic is a wavelength dependence of the phase difference such that a phase difference measured at a long wavelength becomes larger than a phase difference measured at a short wavelength.

JP 2005-156686 A JP 2011-6360 A JP-A-2006-56106 JP 2017-206460 A

The retardation films of Patent Documents 2 to 4 can suppress the above-described problem of display quality of a display with one retardation film.
However, in the retardation films of Patent Documents 2 to 4, even when ultraviolet absorption is used for light degradation countermeasures, the retardation value significantly decreases over time, and the display quality of the image display device deteriorates. That was scattered.

The present inventors have conducted intensive studies. As a result of measuring the transmittance of a liquid crystal compound in the ultraviolet region using linearly polarized light instead of ordinary light (non-polarized light), the inventors have determined that linearly polarized light is horizontally polarized and vertically polarized. It has been found that the transmittance may be different from the case of the above.
The present inventors have further studied and, as a result, taking into account the transmittance of the liquid crystal compound for linearly polarized light in the ultraviolet region, and optimizing the absorption wavelength of the ultraviolet absorber, the retardation of the retardation layer. Has been found to be able to suppress a large decrease over time, and the present invention has been completed.

That is, the present invention provides the following [1] to [3].
[1] A display element (A), a retardation layer (B) arranged on the light emitting surface side of the display element, and an ultraviolet absorbing layer (C) arranged on the light emitting surface side of the retardation layer. A display panel having:
The retardation layer (B) comprises a liquid crystal compound, the retardation layer refractive index in the slow axis direction refractive index is largest and the direction in the plane n _x of _(B), the retardation layer (B) When the refractive index in the fast axis direction, which is the direction orthogonal to the slow axis direction, is ny and the refractive index in the thickness direction of the retardation layer (B) is _nz , the following condition 1 is _satisfied . A display panel that satisfies ~ 3.
<Condition 1>
_{n x>} n _y ≒ n _z, or _{n x} ≒ n z> n _y
<Condition 2>
Linearly polarized light ₁ whose vibration direction is parallel to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), and the phase difference layer (B) Let t ₁ be the spectral transmission spectrum of the linearly polarized light ₁ transmitted through. The linearly polarized light ₁ is horizontal polarized light or vertical polarized light.
Also, linearly polarized light ₂ whose vibration direction is perpendicular to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), B) transmitted through the spectral transmission spectrum of the linearly polarized light ₂ and t _2. When the linearly polarized light ₁ is horizontal polarized light, the linearly polarized light ₂ is vertical polarized light, and when the linearly polarized light ₁ is vertical polarized light, the linearly polarized light ₂ is horizontal polarized light.
t ₁ and t ₂ each have an absorption spectrum in which the transmittance decreases in the wavelength range of 300 to 450 nm toward the shorter wavelength, and the transmission start wavelength of t ₁ is a ₁ (nm) and the transmission of t ₂ When the starting wavelength is a ₂ (nm), the relationship a ₁ ≠ a ₂ is satisfied.
<Condition 3>
From a direction perpendicular to the plane of the ultraviolet absorbing layer (C), incident unpolarized light, a transmission start wavelength based on the spectral transmission spectrum t ₃ of the light transmitted the ultraviolet absorbing layer (C) a ₃ (nm), the following expressions (1) to (3) are satisfied.
a ₁ <a ₃ (1)
a ₂ <a ₃ (2)
a ₃ ≦ 420 nm (3)
[2] An image display device including the display panel according to [1].
[3] A display element (A), a retardation layer (B) arranged on the light emitting surface side of the display element, and an ultraviolet absorbing layer (C) arranged on the light emitting surface side of the retardation layer. In the display panel having
The retardation layer (B) comprises a liquid crystal compound, the retardation layer refractive index in the slow axis direction refractive index is largest and the direction in the plane n _x of _(B), the retardation layer (B) the refractive index n _y in the fast axis direction is a direction perpendicular to the slow axis direction in the _plane, the refractive index in the thickness direction of the retardation layer (B) upon the n _z of
A method for selecting an ultraviolet absorbing layer of a display panel, wherein the ultraviolet absorbing layer (C) is selected so as to satisfy the following conditions 1 ′ to 2 ′.
<Condition 1 '>
_{n x>} n _y ≒ n _z, or _{n x} ≒ n z> n _y
<Condition 2 '>
Linearly polarized light ₁ whose vibration direction is parallel to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), and the phase difference layer (B) Let t ₁ be the spectral transmission spectrum of the linearly polarized light ₁ transmitted through. The linearly polarized light ₁ is horizontal polarized light or vertical polarized light.
Also, linearly polarized light ₂ whose vibration direction is perpendicular to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), B) transmitted through the spectral transmission spectrum of the linearly polarized light ₂ and t _2. When the linearly polarized light ₁ is horizontal polarized light, the linearly polarized light ₂ is vertical polarized light, and when the linearly polarized light ₁ is vertical polarized light, the linearly polarized light ₂ is horizontal polarized light.
t ₁ and t ₂ each have an absorption spectrum in which the transmittance decreases in the wavelength range of 300 to 450 nm toward the shorter wavelength, and the transmission start wavelength of t ₁ is a ₁ (nm) and the transmission of t ₂ The starting wavelength is a ₂ (nm). Further, from the direction perpendicular to the plane of the ultraviolet absorbing layer (C), incident unpolarized light, transmission start wavelength based on the spectral transmission spectrum t ₃ of the light transmitted the ultraviolet absorbing layer (C) Is a ₃ (nm).
Under the above preconditions, the following expressions (1 ′) and (2 ′) are satisfied.
a ₁ ≠ a ₂ <a ₃ (1 ′)
a ₃ ≦ 420 nm (2 ′)

  ADVANTAGE OF THE INVENTION The display panel and image display device of this invention can largely suppress the temporal degradation of a phase difference layer, and can suppress the degradation of display quality over time. Further, according to the method for selecting an ultraviolet absorbing layer of a display panel of the present invention, it is possible to efficiently select an ultraviolet absorbing layer capable of suppressing temporal deterioration of a retardation layer, and to improve display panel production efficiency and yield. Can be improved.

FIG. 1 is a cross-sectional view illustrating one embodiment of a display panel of the present invention. 5 is a schematic diagram illustrating a method for measuring a spectral transmission spectrum t ₁ of linearly polarized light ₁ . Method of measuring the spectral transmission spectrum t ₂ of the linearly polarized light ₂ is a schematic representation illustrating the. 3 is a spectral transmission spectrum of the retardation layer (B) of Example 1. 9 is a spectral transmission spectrum of a retardation layer (B) of Comparative Example 1.

Hereinafter, embodiments of the present invention will be described.
[Display panel]
The display panel according to the present invention includes a display element (A), a retardation layer (B) disposed on the light exit surface side of the display element, and an ultraviolet absorbing layer disposed on the light exit surface side of the retardation layer. (C)
The retardation layer (B) comprises a liquid crystal compound, the retardation layer refractive index in the slow axis direction refractive index is largest and the direction in the plane n _x of _(B), the retardation layer (B) When the refractive index in the fast axis direction, which is the direction orthogonal to the slow axis direction, is ny and the refractive index in the thickness direction of the retardation layer (B) is _nz , the following condition 1 is _satisfied . ~ 3.

<Condition 1>
_{n x>} n _y ≒ n _z, or _{n x} ≒ n z> n _y
<Condition 2>
Linearly polarized light ₁ whose vibration direction is parallel to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), and the phase difference layer (B) Let t ₁ be the spectral transmission spectrum of the linearly polarized light ₁ transmitted through. The linearly polarized light ₁ is horizontal polarized light or vertical polarized light.
Also, linearly polarized light ₂ whose vibration direction is perpendicular to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), B) transmitted through the spectral transmission spectrum of the linearly polarized light ₂ and t _2. When the linearly polarized light ₁ is horizontal polarized light, the linearly polarized light ₂ is vertical polarized light, and when the linearly polarized light ₁ is vertical polarized light, the linearly polarized light ₂ is horizontal polarized light.
t ₁ and t ₂ each have an absorption spectrum in which the transmittance decreases in the wavelength range of 300 to 450 nm toward the shorter wavelength, and the transmission start wavelength of t ₁ is a ₁ (nm) and the transmission of t ₂ When the starting wavelength is a ₂ (nm), the relationship a ₁ ≠ a ₂ is satisfied.
<Condition 3>
From a direction perpendicular to the plane of the ultraviolet absorbing layer (C), incident unpolarized light, a transmission start wavelength based on the spectral transmission spectrum t ₃ of the light transmitted the ultraviolet absorbing layer (C) a ₃ (nm), the following expressions (1) to (3) are satisfied.
a ₁ <a ₃ (1)
a ₂ <a ₃ (2)
a ₃ ≦ 420 nm (3)

  FIG. 1 is a sectional view showing an embodiment of the display panel 100 of the present invention. The display panel 100 in FIG. 1 includes a display element (A) 10, a retardation layer (B) 20 disposed on the light exit surface side of the display element, and a retardation layer (B) 20 disposed on the light exit surface side of the retardation layer. An ultraviolet absorbing layer (C) 30.

When the display panel of the present invention satisfies the above conditions 1 to 3, the temporal deterioration of the retardation layer over time can be significantly suppressed, and the deterioration of the display quality over time can be suppressed.
Hereinafter, the technical significance of the conditions 1 to 3 will be described.

<< Condition 1 >>
Condition ₁ defines that satisfy _n x> n _y ≒ n _z, or _{n x ≒ n z> n y} . In other words, Condition 1 specifies that the retardation layer (B) is a positive A plate or a negative A plate.
The retardation layer (B) satisfying the condition 1 can be used, for example, as a λ / 2 retardation layer, a λ / 4 retardation layer, or the like.

In condition _1, in the case of _{n x> n y ≒ n z} , it is preferable that the absolute value of the difference between _{n y} and _{n z} is 0.03 or less, more preferably 0.02 or less.
When _nx ≒ _nz > _ny , the absolute value of the difference between _nx and _nz is preferably 0.03 or less, more preferably 0.02 or less.

<< Condition 2 >>
Condition 2 defines a relationship of a ₁ ≠ a ₂ .

FIG. 2 is a schematic diagram illustrating a method of measuring “spectral transmission spectrum t ₁ of linearly polarized light ₁ ” from which a ₁ is determined.
As shown in FIG. 2, when measuring the spectral transmission spectrum t ₁ of the linearly polarized light _1, first, a phase difference layer (B) in a direction perpendicular to 20 the plane, vibration direction retardation layer (B) The linearly polarized light ₁ parallel to the direction of the slow axis 20 is incident. Dotted lines in FIG. 2 and FIG. 3 described later indicate the arrangement direction of the slow axis. Then, by calculating the phase difference layer (B) 20 transmittance of linearly polarized light ₁ that has passed through the each wavelength, it is possible to obtain the spectral transmission spectrum t _1. Note that the linearly polarized light ₁ is horizontal polarized light or vertical polarized light.
The spectral transmission spectrum t ₁ and the spectral transmission spectrum t ₂ described later are measured by turning on a polarizing filter using, for example, an ultraviolet-visible-near-infrared spectrophotometer “V7100” manufactured by JASCO Corporation. be able to. In the spectrophotometer, the linearly polarized light ₁ and the linearly polarized light ₂ can be switched between P-polarized light and S-polarized light. Note that the spectral transmission spectrum is preferably measured using a tungsten halogen light source or a deuterium light source as a light source and a measurement wavelength pitch of 1 nm.
Further, t ₁ and t ₂ may be measured in a state of a laminate in which the retardation layer (B) is laminated with another layer. Other layers include a transparent substrate and an alignment film. However, as the other layer, and the spectral transmittance at a wavelength of _{a 1} and _{a 2} of the other layer 90% or more, and the spectral transmission spectrum of the wavelength 300~450nm linearly polarized light ₁ of the other layers The other layer has substantially the same spectral transmission spectrum as that of the linearly polarized light _{2 at} a wavelength of 300 to 450 nm. "Substantially equal" means that the difference between the average of the spectral transmission spectrum of linearly polarized light _{1 at} a wavelength of 300 to 450 nm and the average of the linearly polarized light _{2 at} a wavelength of 300 to 450 nm is 1% or less.

FIG. 3 is a schematic diagram illustrating a method of measuring “spectral transmission spectrum t ₂ of linearly polarized light ₂ ” from which a ₂ is determined.
As shown in FIG. 3, when measuring the spectral transmission spectrum t ₂ of the linearly polarized light ₂ is first retardation layer (B) in a direction perpendicular to 20 the plane, vibration direction retardation layer (B) The linearly polarized light ₂ perpendicular to the direction of the slow axis 20 is incident. Then, by calculating the phase difference layer (B) 20 transmittance of linearly polarized light ₂ transmitted through each wavelength, it is possible to obtain the spectral transmission spectrum t _2.
When the linearly polarized light ₁ is horizontal polarized light, the linearly polarized light ₂ is vertical polarized light, and when the linearly polarized light ₁ is vertical polarized light, the linearly polarized light ₂ is horizontal polarized light.

FIG. 4 is a spectral transmission spectrum of the retardation layer (B) used in the display panel of Example 1. In FIG. 4, the solid line indicates the spectral transmission spectrum of unpolarized light, the dotted line indicates the spectral transmission spectrum t ₁ of linearly polarized light ₁ , and the dashed line indicates the spectral transmission spectrum t ₂ of linearly polarized light ₂ .
From FIG. 4, the retardation layer (B) used in Example 1 has an absorption spectrum in which the transmittance decreases in the wavelength region of 300 to 450 nm toward the side where the wavelength becomes shorter, and is linearly polarized. _It can be confirmed that the transmission start wavelength a ₁ (374 nm) of No. ₁ is different from the transmission start wavelength a ₂ (389 nm) of the linearly polarized light ₂ . That is, the retardation layer (B) used in the first embodiment satisfies the condition 2 by satisfying the relationship of a ₁ ≠ a ₂ .

Generally, an absorption spectrum in a wavelength range of 300 to 450 nm causes deterioration of a compound such as a liquid crystal compound.
As in the retardation layer (B) used in the first embodiment, the relationship of a ₁ ≠ a ₂ is satisfied and the condition 2 is satisfied when the case of the horizontally polarized light and the case of the vertically polarized light are as follows. This means that the transmission start wavelength that deteriorates the liquid crystal compound is different.

FIG. 5 shows a spectral transmission spectrum of the retardation layer (B) used for the display panel of Comparative Example 1. In FIG. 5, the solid line polarized non spectral transmission spectrum of light, the dotted line spectral transmission spectrum t ₁ of the linearly polarized light _1, the dashed line represents the spectral transmission spectrum t ₂ of the linearly polarized light _2.
From FIG. 5, the retardation layer (B) used in Comparative Example 1 has an absorption spectrum in which the transmittance decreases in the wavelength region of 300 to 450 nm toward the shorter wavelength, but has a straight line. and transmission start wavelength _a 1 polarization ₁ (308 nm), transmission start wavelength _a 2 of the linearly polarized light ₂ and (308 nm) can be confirmed to be substantially the same. In other words, the retardation layer (B) used in Comparative Example 1 does not satisfy the relationship of a ₁ ≠ a ₂ and does not satisfy the condition 2.

In this specification, the transmission start wavelength and the absorption start wavelength are calculated as in the following (A1) to (A4).
(A1) The average of the spectral transmittance from 450 to 500 nm is defined as T (%).
(A2) Among the wavelengths at which the spectral transmittance is T / 2 (%) or less, let the longest wavelength be x (nm).
(A3) The spectral transmittance at x-15 (nm) is y1 (%), and the spectral transmittance at x + 15 (nm) is y2 (%).
(A4) When a straight line connecting point 1 (x-15, y1) and point 2 (x + 15, y2) is set to y = f (x), the wavelength when the straight line intersects with the transmittance of 0% is transmitted. The wavelength at which the straight line intersects with the transmittance T% is defined as the start wavelength.

In this specification, transmission start wavelength a ₁ , transmission start wavelength a ₂ , transmission start wavelength a ₄ and transmission start wavelength a ₅ , absorption start wavelength b ₁ , absorption start wavelength b ₂ , absorption start wavelength b ₄ and absorption start wavelength b ₅ refers to those retardation layer transmission start wavelength and the absorption start wavelength were calculated from the spectral transmittance measured at 16 points of the (B) were averaged. Similarly, transmission start wavelength a ₃ and the absorption start wavelength a ₃ refers to those ultraviolet-absorbing layer the transmitted start wavelength and the absorption start wavelength were calculated from the spectral transmittance measured at 16 points of the (C) were averaged. In addition, _nx , _ny , _nz , in-plane retardation, and retardation in the thickness direction mean values obtained by averaging 16 measured values of the retardation layer (B).
The 16 measurement points were measured at 16 intersection points when a line dividing the vertical and horizontal directions into five equal parts was drawn with respect to the area inside the margin with the area 1 cm from the outer edge of the measurement sample as the margin. Is preferably the center. For example, when the measurement sample is a quadrangle, the measurement is performed centering on 16 points at the intersection of the dotted lines obtained by equally dividing the area 1 cm from the outer edge of the quadrilateral into five in the vertical and horizontal directions. , It is preferable to calculate the parameter by its average value. When the measurement sample has a shape other than a quadrangle such as a circle, an ellipse, a triangle, and a pentagon, it is preferable to draw a quadrilateral inscribed in these shapes, and to measure the quadrilateral at 16 points by the above method.

<< Condition 3 >>
Condition 3 is that a non-polarized light is incident from a direction perpendicular to the plane of the ultraviolet absorbing layer (C), and a transmission start wavelength based on a spectral transmission spectrum t ₃ of light transmitted through the ultraviolet absorbing layer (C). Satisfies the following expressions (1) to (3) when a ₃ (nm).
a ₁ <a ₃ (1)
a ₂ <a ₃ (2)
a ₃ ≦ 420 nm (3)

Spectral transmission spectrum t ₃ can be measured by a general-purpose spectrophotometer. Note that the spectral transmission spectrum is preferably measured using a deuterium light source or a xenon light source as the light source and a measurement wavelength pitch of 1 nm.

As described above, that the retardation layer (B) satisfies the condition 2 means that the linearly polarized light ₁ and the linearly polarized light ₂ have different transmission start wavelengths that deteriorate the liquid crystal compound of the retardation layer (B). ing. In other words, that the retardation layer (B) satisfies the condition 2 means that the horizontal polarization and the vertical polarization have different transmission start wavelengths that deteriorate the liquid crystal compound of the retardation layer (B).
Therefore, when the retardation layer (B) satisfies the condition 2, the transmission start wavelength based on the spectral transmission spectrum of the ultraviolet absorbing layer (C) is considered in consideration of both the transmission start wavelength of the horizontal polarization and the transmission start wavelength of the vertical polarization. It is important to determine

Even in the conventional product design, by calculating the transmission start wavelength based on the spectral transmission spectrum of the object whose UV deterioration is to be suppressed, by selecting the ultraviolet absorption layer whose transmission start wavelength is longer on the long wavelength side than the transmission start wavelength. It has been practiced to suppress deterioration due to ultraviolet rays.
However, in the conventional product design, the spectral transmission spectrum of an object is measured exclusively with non-polarized light. This is because it has not conventionally been assumed that the transmission start wavelength of the object may be different between the horizontally polarized light and the vertically polarized light. Then, as shown in FIG. 4, the unpolarized spectral transmission spectrum is located between the horizontally polarized spectral transmission spectrum and the vertically polarized spectral transmission spectrum. In order to avoid adverse effects on the displayed image, it is required that the transmission start wavelength of the ultraviolet absorbing layer be as short as possible. Therefore, referring to FIG. 4 as an example, the conventional product design does not consider the transmission start wavelength (389 nm) of the dashed-dotted spectral transmission spectrum but only considers the transmission start wavelength (381 nm) of the solid spectral transmission spectrum. Since an ultraviolet absorber having a transmission start wavelength slightly exceeding 381 nm was selected, it was not possible to suppress the latter light degradation of the compound due to the transmission start wavelength.
On the other hand, the present inventors have found that the transmission start wavelength of the liquid crystal compound as an object may be different between horizontal polarized light and vertical polarized light, and the transmission start wavelength is longer than the transmission start wavelength of horizontal polarized light and vertical polarized light. By selecting an ultraviolet absorbing layer on the long wavelength side, it is possible to suppress ultraviolet degradation of the liquid crystal compound, and the present invention has been completed.

Condition 2 tends to be easily satisfied when the retardation layer (B) contains a liquid crystal compound having a side chain. First, in order to satisfy the condition 1, in the liquid crystal compound having a side chain, the main chain of the liquid crystal compound is regularly arranged in a certain direction in a plane. By arranging the main chains of the liquid crystal compound as described above, the direction of the slow axis is constant in the plane of the retardation layer (B), and Condition 1 can be satisfied. Then, at that time, the side chain is oriented in the z-axis direction.
As described above, in a state where the direction of the slow axis is regularly arranged in a certain direction in the plane of the retardation layer (B), the linearly polarized light ₁ whose vibration direction is parallel to the direction of the slow axis is incident, and The spectral transmission spectrum t ₁ of the linearly polarized light ₁ transmitted through the phase difference layer (B) can be simulated as the spectral transmission spectrum of the main chain. The transmission start wavelength a ₁ calculated from the spectral transmission spectrum t ₁ may transmissive start wavelength and fiction backbone. On the other hand, in a state where the direction of the slow axis is regularly arranged in a certain direction in the plane of the phase difference layer (B), linearly polarized light ₂ whose vibration direction is perpendicular to the direction of the slow axis is incident, and the phase difference layer ( spectral transmission spectrum t ₂ of the linearly polarized light ₂ transmitted through the B) may spectral transmission spectrum and fiction of the side chain. The transmission start wavelength a ₂ calculated from the spectral transmission spectrum t ₂ may transmissive start wavelength and fiction of the side chain.
In the liquid crystal compound having a side chain, a transmission start wavelength a ₁ backbone, when compared with the transmission start wavelength a ₂ side chains, different tendency is high both. In particular, when the phase difference layer (B) has a reverse dispersion characteristics, side chains to have necessarily different group of optical properties and the main chain, the difference tends to become larger with a ₁ and a _2.
Incidentally, generally, than the transmission start wavelength a ₁ backbone, tends to located towards the long wavelength side of the transmission start wavelength a ₂ of the side chain is high.

And transmission start wavelength a ₁ backbone, when the transmission start wavelength a ₂ of the side chain is different, to meet both of the above formula (1) and (2), can not suppress light degradation of the liquid crystal compound. For example, when the above formula (1) is satisfied but the above formula (2) is not satisfied, light degradation of the side chain triggers and the entire liquid crystal compound including the main chain is deteriorated.
Therefore, it is important to satisfy both the expressions (1) and (2). As described above, when the phase difference layer (B) has a reverse dispersion characteristics, a transmission start wavelength a ₁ in the main chain, the difference between the transmission start wavelength a ₂ of the side chain tends to be large. Therefore, the present invention is effective in that when the retardation layer (B) has reverse dispersion characteristics, the effect is more easily exhibited.

In addition, when the condition (3) is not satisfied in the condition 3, the light in the short wavelength region of the visible light region is absorbed by the ultraviolet absorbing layer (B), and the displayed image becomes yellowish and the tint becomes poor. Will be spoiled.
Preferably a ₃ is 410nm or less, more preferably 400nm or less, and more preferably less 395 nm.

When the display panel of the present invention satisfies the conditions 1 to 3, it is more preferable that the following condition 4 is further satisfied.
<< Condition 4 >>
as the wavelength of a ₁ and _{a 2} is large, the difference between _{a 3} or more 2nm

  By satisfying condition 4, light degradation of the liquid crystal compound can be further suppressed. More preferably, the difference in condition 4 is 3 nm or more. Further, the difference in Condition 4 is preferably 20 nm or less, and more preferably 10 nm or less.

When the display panel of the present invention satisfies the conditions 1 to 3, the absorption start wavelength of t ₁ is b ₁ (nm), the absorption start wavelength of t ₂ is b ₂ (nm), and the ultraviolet light absorption layer (C) starts absorption. When the wavelength is b ₃ (nm), it is preferable to satisfy the relationship described later.

b _3, from the viewpoint of suppressing compromising the color of the displayed image, preferably at 450nm or less, and more preferably less 430 nm.
In addition, from the viewpoint of suppressing the light deterioration of the liquid crystal compound while suppressing the impairment of the color of the display image, b ₃ -a ₃ is preferably from 20 to 40 nm, more preferably from 25 to 38 nm. More preferably, it is 30 to 36 nm.

When b ₃ -a ₃ is X ₃ (nm), b ₂ -a ₂ is X ₂ (nm), and b ₁ -a ₁ is X ₁ (nm), the absolute value of X ₃ -X ₂ Is preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 3 nm or less. Further, the absolute value of X ₃ -X ₁ is preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 3 nm or less.
By setting X ₃ -X ₂ and X ₃ -X ₁ within the above ranges, it is possible to easily suppress the light deterioration of the liquid crystal compound while suppressing the impairment of the tint of the displayed image.

the difference between a ₁ and _{a 2} is not particularly limited, the absolute value of the difference between _{a 1} and _{a 2 (| a 1 -a 2} |) is preferably set to 3~25nm to, be 5~22nm , More preferably 8 to 20 nm, even more preferably 11 to 18 nm.
By setting the absolute value to 3 nm or more, the effect of the configuration of the present invention can be made more effective. Moreover, by the said absolute value with 25nm or less, it is possible also to easily satisfy the above formula (1) and (2) a a ₃ as the short wavelength side, is color image to be displayed becomes yellowish Damage can be easily suppressed.

Although not specifically limited wavelength of _{a 1} and _{a 2} is preferably a wavelength ones wavelengths less of _{a 1} and _{a 2} are 350 to 400 nm, more preferably 360～390Nm.
When the wavelength of a ₁ and a ₂ having a smaller wavelength is within the above range, the transmission start wavelength of the unpolarized light is shifted to a longer wavelength side than the above range, and includes the lower wavelength side of the visible light region. There is. Therefore, when selecting an ultraviolet absorber based on the transmission start wavelength of non-polarized light, an ultraviolet absorber having a transmission start wavelength equivalent to the transmission start wavelength of non-polarized light is selected as much as possible. However, this cannot suppress the photodeterioration of the liquid crystal compound caused by polarized light whose transmission start wavelength is located on the long wavelength side.
On the other hand, in the present invention, the wavelength of one wavelength is less of a ₁ and a ₂ are, in the case, which may include a low wavelength side in the visible light region as described above, an ultraviolet absorber that can suppress light degradation of the liquid crystal compound It is effective in that it can be selected appropriately.

<Display element>
Examples of the display element include a liquid crystal display element, an EL (inorganic EL, organic EL) display element, a plasma display element, an LED display element (such as a micro LED), a display element using quantum dots, and the like. Note that the liquid crystal display element may be an in-cell touch panel liquid crystal display element having a touch panel function in the element.

  Among the display elements, the organic EL element and the micro LED element have high reflectivity, so that the ultraviolet light passes through the retardation layer (B) twice, and the retardation layer (B) tends to deteriorate easily. Therefore, when the display element is an organic EL element or a micro LED element, the effect of the present invention is more effectively exhibited.

  The organic EL display element has, for example, a configuration in which a transparent electrode layer, a hole injection layer, a hole transport layer, a light emitting layer, an electron injection layer, and an electrode layer are sequentially stacked from the light emitting side. The organic EL display panel can be applied to a passive drive type organic EL display device and an active drive type organic EL display device.

  When the display element is a liquid crystal display element, a backlight is required on the back of the liquid crystal display element.

<Retardation layer (B)>
The retardation layer (B) is a layer containing a liquid crystal compound, and is arranged on the light emitting surface side of the display element.
The retardation layer (B) is not particularly limited as long as it satisfies the conditions 1 and 2.
The ratio of the liquid crystal compound in the retardation layer is preferably from 60 to 99.9% by mass, more preferably from 65 to 98% by mass, based on the total solids of the retardation layer.

The retardation layer (B) has an in-plane retardation of the retardation layer (B) at a wavelength of 450 nm of Re (450), the in-plane retardation of the retardation layer (B) of a wavelength of 550 nm is Re (550), and the retardation When the in-plane retardation at a wavelength of 650 nm of the layer (B) is defined as Re (650), it is preferable that the following formula (i) is satisfied.
Re (450) <Re (550) <Re (650) (i)

Satisfying the above equation (i) means that the retardation layer (B) shows inverse dispersion characteristics. By satisfying the above expression (i), the color in the oblique direction can be easily improved.
In this specification, the in-plane retardation (Re) and the thickness direction retardation (Rth) _is from _{n x,} n _y, n _z and a thickness (d (nm)), those represented by the following formula Means
In-plane retardation (Re) = (nx−ny) × d
Phase difference (Rth) in thickness direction = ((nx + ny) / 2−nz) × d

The retardation layer (B) preferably further satisfies the following formula (ii).
0.75 ≦ Re (450) / Re (550) ≦ 0.98 (ii)

  By satisfying the above expression (ii), the color in the oblique direction can be more easily improved. In the above formula (ii), Re (450) / Re (550) is more preferably 0.80 or more and 0.95 or less, further preferably 0.82 or more and 0.93 or less.

The retardation layer (B) preferably satisfies the following formula (iii).
80 nm ≦ Re (550) ≦ 220 nm (iii)

The fact that the retardation layer (B) further satisfies the above expression (iii) means that the retardation layer (B) functions as a λ / 4 retardation layer. When the retardation layer (B) satisfies the above expression (iii) and the polarizer is disposed on the light emitting surface side of the retardation layer (B), the retardation layer (B) and the polarizer are circular. It functions as a polarizing plate and can suppress external light reflection.
In the above formula (iii), Re (550) is more preferably 90 nm or more and 200 nm or less, further preferably 100 nm or more and 180 nm or less.

  The retardation layer (B) that satisfies the above formula (iii) and the polarizer are set so that the angle between the absorption axis of the polarizer and the slow axis of the retardation layer (B) is 45 ± 5 °. It is preferable to arrange them, and it is more preferable to arrange them so as to be 45 ± 2 °.

The thickness direction retardation at a wavelength of 550nm of the retardation layer (B) (Rth (550) ) _is preferably in the case of _n x> n _y ≒ n _z is 30nm or more 120nm or less, 50 nm or more 100nm more preferably less, preferably in the case of _{n x} ≒ _n z> _{n y} is less than -30nm or -120 nm, more preferably less than -100 nm -50 nm.

<< liquid crystal compound >>
The liquid crystal compound contained in the retardation layer (B) is not particularly limited as long as it satisfies the conditions 1 and 2.

  The liquid crystal compound that satisfies the conditions 1 and 2 preferably has a main chain and a side chain, and the main chain can be arranged in a certain direction in the plane of the retardation layer (B). Further, the liquid crystal compound preferably has reverse dispersion characteristics.

  A liquid crystal compound having a main chain and side chains, in which the main chain can be arranged in a certain direction in the plane of the retardation layer (B), and having a reverse dispersion property is a structural unit derived from a rod-shaped polymerized liquid crystal compound. And a structural unit derived from a polymerizable compound exhibiting reverse dispersion characteristics. Such a liquid crystal compound is disclosed in, for example, JP-A-2011-6360, JP-A-2006-56106, JP-A-2017-206460, JP-T-2010-522892 (Patent No. 5670179), JP-A-2007-2209, JP-A-2010-31223, JP-A-6055569, and the like can be mentioned.

  Examples of the rod-shaped polymerized liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, and alkoxy-substituted phenylpyrimidines. , Phenyldioxane, tolan and alkenylcyclohexylbenzonitrile are preferably used. As the rod-shaped liquid crystal compound, not only these low-molecular liquid crystal compounds but also high-molecular liquid crystal compounds can be used. Further, the rod-shaped liquid crystal compound preferably has a polymerizable group. The number of polymerizable groups in one molecule of the rod-shaped liquid crystal compound is preferably 2 to 3.

Specific examples of the rod-shaped liquid crystal compound include compounds represented by the following formulas (1) to (17).

  Examples of the polymerizable compound exhibiting the inverse dispersion property include “compound having a group represented by formula (A)” described in JP-A-2010-31223 and “polymerization described in JP-A-2007-2209”. Compound (1) "and" Compound (1) "described in JP-A-2011-6360.

Further, a liquid crystal compound having a main chain and side chains, in which the main chain can be arranged in a certain direction in the plane of the retardation layer (B), and having a reverse dispersion characteristic, is derived from a disc-shaped core. Those containing a unit (main chain) and a structural unit derived from a polymerizable compound exhibiting reverse dispersion characteristics can also be preferably used. Such a liquid crystal compound is called a discotic liquid crystal compound, and examples thereof include a compound represented by the following formula.
D (-LP) _n
In the formula, D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 1 to 12. Preferred specific examples of the discotic core (D), the divalent linking group (L) and the polymerizable group (P) in the above formula are (D1) to (D15) described in JP-A-2001-4837, respectively. ), (L1) to (L25), and (P1) to (P18), and the contents described in the publication can be preferably used. In addition, the discotic nematic liquid crystal phase-solid phase transition temperature of the liquid crystal compound is preferably 30 to 300C, more preferably 30 to 170C.

  Discotic liquid crystalline compounds are described in various publications (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by The Chemical Society of Japan, quarterly chemistry review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10, Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J. Am. Chem. Soc., Vol. 116, page 2655 (1994)). The polymerization of discotic liquid crystalline compounds is described in JP-A-8-27284.

<Method of forming retardation layer (B)>
The retardation layer (B) is formed by coating a retardation layer-forming composition containing a liquid crystal compound on a transparent substrate or on an alignment film of a transparent substrate provided with an alignment film. It can be formed by curing. Further, the retardation layer (B) formed as described above may be transferred onto another transparent substrate.
Specific drying conditions vary depending on the phase difference layer forming composition, and thus cannot be unconditionally determined. However, the drying temperature is preferably 70 to 150 ° C., the drying time is preferably 30 to 250 seconds, and the drying temperature is 90 to 130. More preferably, the drying time is 50 to 200 seconds.
Light irradiation for polymerizing the polymerizable liquid crystal compound is preferably performed using ultraviolet light. The irradiation energy of a specific ultraviolet radiation can not be said sweepingly because it varies by such thickness of the retardation layer is preferably ^{50mJ / cm 2 ~1J / cm 2} , at 150mJ / cm ² ~900mJ / cm 2 More preferably, there is.

<Composition for forming retardation layer>
The composition for forming a retardation layer may contain a photopolymerization initiator, a solvent, a surfactant and the like as components other than constituting the liquid crystal compound.

<< Photopolymerization initiator >>
The composition for forming a retardation layer preferably contains a photopolymerization initiator. Examples of the photopolymerization initiator include acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyldimethyl ketal, benzoylbenzoate, α-acyl oxime ester, and thioxanthone.
The content of the photopolymerization initiator is preferably from 0.01 to 20% by mass, more preferably from 0.5 to 5% by mass of the total solids of the composition for forming a retardation layer.

<< Surfactant >>
The composition for forming a retardation layer preferably contains a surfactant. Further, among the surfactants, it is preferable to select and use at least one selected from a fluorine-based surfactant having a polymerizable group and a silicon-based surfactant having a polymerizable group.
The content of the surfactant is preferably from 0.01 to 2.0% by mass, more preferably from 0.1 to 1.0% by mass of the total solids of the composition for forming a retardation layer.

<< Solvent >>
The composition for forming a retardation layer usually contains a solvent.
Solvents include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatics Group hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (butanol, cyclohexanol, etc.), cellosolves (methyl Cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethylsulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.) and the like, and mixtures thereof.
The content of the solvent in the retardation layer forming composition is preferably 50 to 90% by mass, more preferably 70 to 80% by mass in the retardation layer forming composition.

<Transparent substrate>
The display panel of the present invention may have a transparent substrate.
The transparent substrate has a role as a support when forming the retardation layer, a role to protect the retardation layer, a role as one member constituting the ultraviolet absorbing layer (C), and the like.

The transparent substrate is preferably one that is optically isotropic. The transparent substrate may be formed from a polymer or may be formed from glass.
Examples of the polymer include cellulose acylate, polycarbonate polymer, polyester polymer such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymer such as polymethyl methacrylate, and styrene polymer such as polystyrene and acrylonitrile-styrene copolymer (AS resin). Etc. can be used. Polyolefins such as polyethylene and polypropylene; polyolefin polymers such as ethylene-propylene copolymer; vinyl chloride polymers; amide polymers such as nylon and aromatic polyamide; imide polymers; sulfone polymers; and polyethersulfone polymers. , A polyether ether ketone polymer, a polyphenylene sulfide polymer, a vinylidene chloride polymer, a vinyl alcohol polymer, a vinyl butyral polymer, an arylate polymer, a polyoxymethylene polymer, an epoxy polymer, or a mixture of these polymers. Can be

  The thickness of the transparent substrate is usually about 25 to 125 μm in the case of a transparent substrate formed of a polymer, and is usually about 100 μm to 5 mm in the case of a transparent substrate formed of glass.

<Orientation film>
The alignment film is preferably a “horizontal alignment film” that facilitates alignment of the liquid crystal compound in a certain direction in the plane.
In addition, even if it has an alignment film at the time of forming the retardation layer (B), the retardation layer (B) is transferred to another member (for example, a polarizer) and the alignment film is not transferred during the transfer. By doing so, a display panel having no alignment film can be obtained.

<< horizontal alignment film >>
The horizontal alignment film is an alignment film having an alignment regulating force in the horizontal direction, and various types of horizontal alignment films used for producing a known A-type retardation film can be applied. For example, a light dimerization type material or the like can be used. Can be applied.
The means for imparting the alignment regulating force to the horizontal alignment film may be a conventionally known means, and examples thereof include a rubbing method, a photo-alignment method, and a shaping method.
The thickness of the horizontal alignment film is usually 1 to 1000 nm, preferably 60 to 300 nm.

<Ultraviolet absorbing layer (C)>
The ultraviolet absorbing layer (C) may be a single layer of a resin layer containing an ultraviolet absorbent, or may be a multilayer such as a laminated structure of a transparent substrate and a resin layer containing an ultraviolet absorbent. The resin layer containing an ultraviolet absorber can be formed from, for example, an ultraviolet absorber and a binder resin.
As the transparent substrate constituting the ultraviolet absorbing layer (C), the same ones as those exemplified above can be used. The transparent base material constituting the ultraviolet absorbing layer (C) may be a material obtained by kneading an ultraviolet absorber in the transparent base material exemplified above.

<<<< UV absorber >>
The ultraviolet absorber can be used without any particular limitation as long as it satisfies the expressions (1) to (3) of the condition 3.
Examples of the ultraviolet absorber include a benzotriazole-based ultraviolet agent, a benzophenone-based ultraviolet absorber, and a triazine-based ultraviolet absorber.

  Further, the ultraviolet absorber is preferably provided with a reactive group capable of performing a crosslinking reaction with a binder resin from the viewpoint of suppressing bleed-out.

<< Binder resin >>
As the binder resin of the resin layer containing the ultraviolet absorber, one kind selected from general-purpose thermoplastic resins, thermosetting resins, and ionizing radiation-curable resins, or a mixture of two or more kinds selected from these may be used.
In addition, it is preferable that the binder resin has an adhesive property in that it can be laminated with another layer (a retardation layer (B), a polarizer, or the like) without an adhesive layer.

The content of the ultraviolet absorbent in the resin layer containing the ultraviolet absorbent is preferably from 10 to 45% by mass, more preferably from 15 to 40% by mass of the total solids of the layer.
Further, the thickness of the layer containing the ultraviolet absorbent is preferably from 0.5 to 10 μm, more preferably from 0.7 to 5 μm.

<Other layers>
On the light emitting surface side of the display element (A), layers or members other than the retardation layer (B) and the ultraviolet absorbing layer (C) may be provided.
Examples of the other layers include the above-mentioned transparent base material and alignment film, and further include a retardation layer other than the retardation layer (B), a polarizer, a polarizer protective film, an adhesive layer, and a functional layer. Can be Other members include a touch panel.

<Specific laminated structure of display panel>
The specific layered configuration of the display panel is not particularly limited, and examples thereof include the following configurations (1) to (3). Note that “/” indicates an interface between layers.
(1) Display element (A) / adhesive layer / transparent substrate / adhesive layer / retardation layer (B) / adhesive layer / ultraviolet light obtained by laminating transparent substrate and resin layer containing ultraviolet absorber Absorbing layer (C) / adhesive layer / polarizer / adhesive layer / polarizer protective film (2) Display element (A) / adhesive layer / retardation layer (B) / adhesive layer / transparent substrate and ultraviolet light UV-absorbing layer (C) / adhesive layer / polarizer / adhesive layer / polarizer protective film (3) display element (A) / adhesive layer / retardation layer obtained by laminating resin layer containing absorber (B) / ultraviolet absorbing layer containing ultraviolet absorber (C) / adhesive layer / polarizer / adhesive layer / polarizer protective film

[Image display device]
An image display device according to the present invention includes the above-described display panel according to the present invention.

  It is preferable that the image display device includes the display panel of the present invention described above, a drive control unit electrically connected to the display panel, and a housing for accommodating them.

[Selection method of ultraviolet absorbing layer of display panel]
The method for selecting the ultraviolet absorbing layer of the display panel according to the present invention includes:
A display having a display element (A), a retardation layer (B) arranged on the light emitting surface side of the display element, and an ultraviolet absorbing layer (C) arranged on the light emitting surface side of the retardation layer. In the panel,
The retardation layer (B) comprises a liquid crystal compound, the retardation layer refractive index in the slow axis direction refractive index is largest and the direction in the plane n _x of _(B), the retardation layer (B) the refractive index n _y in the fast axis direction is a direction perpendicular to the slow axis direction in the _plane, the refractive index in the thickness direction of the retardation layer (B) upon the n _z of
The ultraviolet absorbing layer (C) is selected so as to satisfy the following conditions 1 ′ to 2 ′.
<Condition 1 '>
_{n x>} n _y ≒ n _z, or _{n x} ≒ n z> n _y
<Condition 2 '>
Linearly polarized light ₁ whose vibration direction is parallel to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), and the phase difference layer (B) Let t ₁ be the spectral transmission spectrum of the linearly polarized light ₁ transmitted through. The linearly polarized light ₁ is horizontal polarized light or vertical polarized light.
Also, linearly polarized light ₂ whose vibration direction is perpendicular to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), B) transmitted through the spectral transmission spectrum of the linearly polarized light ₂ and t _2. When the linearly polarized light ₁ is horizontal polarized light, the linearly polarized light ₂ is vertical polarized light, and when the linearly polarized light ₁ is vertical polarized light, the linearly polarized light ₂ is horizontal polarized light.
t ₁ and t ₂ each have an absorption spectrum in which the transmittance decreases in the wavelength range of 300 to 450 nm toward the shorter wavelength, and the transmission start wavelength of t ₁ is a ₁ (nm) and the transmission of t ₂ The starting wavelength is a ₂ (nm). Further, from the direction perpendicular to the plane of the ultraviolet absorbing layer (C), incident unpolarized light, transmission start wavelength based on the spectral transmission spectrum t ₃ of the light transmitted the ultraviolet absorbing layer (C) Is a ₃ (nm).
Under the above preconditions, the following expressions (1 ′) and (2 ′) are satisfied.
a ₁ ≠ a ₂ <a ₃ (1 ′)
a ₃ ≦ 420 nm (2 ′)

  Condition 1 'corresponds to condition 1 for the display panel of the present invention described above. The condition 2 'is a combination of the above conditions 2 and 3 of the display panel of the present invention.

  ADVANTAGE OF THE INVENTION According to the selection method of the ultraviolet absorption layer of the display panel of this invention, the ultraviolet absorption layer which can suppress the temporal deterioration of a phase difference layer can be selected efficiently, and the production efficiency and the yield of a display panel improve. can do.

The method for selecting an ultraviolet absorbing layer of a display panel according to the present invention has the above-described effect when the configuration of the retardation layer (B) is a preferred embodiment of the above-described retardation layer (B) of the display panel of the present invention. It is preferable in that it can be more effective.
Further, the method for selecting an ultraviolet absorbing layer of the display panel of the present invention is characterized in that, when the configuration of the ultraviolet absorbing layer (C) is a preferred embodiment of the above-described ultraviolet absorbing layer (C) of the display panel of the present invention, This is preferable in that the effect can be made more effective.

  Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Note that “parts” and “%” are based on mass unless otherwise specified.

1. Measurement and evaluation The following measurement and evaluation were performed on the retardation layer and the ultraviolet absorbing layer obtained in the examples and comparative examples.

1-1. Measurement of Refractive Index and Retardation Using the trade name “KOBRA-WR (measurement spot: diameter 5 mm)” manufactured by Oji Scientific Instruments, the refractive indices ( _nx , _ny and _nz ), the in-plane retardation and the thickness direction retardation were measured. Table 1 shows the results.

1-2. Calculation of transmission start wavelengths a ₁ and a ₂ , and absorption start wavelengths b ₁ and b ₂ According to the measurement method described in the specification, the spectral transmission spectra t ₁ and linear polarized light ₁ of the phase difference layers of the phase difference films 1 to 8 and measuring the spectral transmission spectrum _{t 2} of the linearly polarized light _2, transmission start wavelength _{a 1} and _{a 2,} as well, was calculated absorption start wavelength _{b 1} and _{b 2.} Table 1 shows the results.
The spectral transmission spectrum t ₁ and the spectral transmission spectrum t ₂ were measured by using a trade name “V-7100” manufactured by JASCO Corporation by turning on the polarizing filter. As a light source, a deuterium lamp and a tungsten halogen lamp were used (a deuterium lamp was used for a wavelength of 350 nm or less, and a tungsten halogen lamp was used for other wavelengths. The wavelength was automatically switched in the apparatus), and the measurement wavelength pitch was 1 nm.

1-3. According to the measuring method calculating specification Text of transmission start wavelength a ₃ and the absorption start wavelength b _3, the spectral transmission spectrum t ₃ of the unpolarized ultraviolet absorbing layer (C) 1 to 4 were measured, the transmission start wavelength a ₃ and the absorption It was calculated start wavelength _{b 3.} Table 2 shows the results.
It should be noted that the spectral transmission spectrum t ₃ is, JASCO Corporation under the trade name using the "V-7100", to measure the polarization filter as OFF. As a light source, a deuterium lamp and a tungsten halogen lamp were used (a deuterium lamp was used for a wavelength of 350 nm or less, and a tungsten halogen lamp was used for other wavelengths. The wavelength was automatically switched in the apparatus), and the measurement wavelength pitch was 1 nm.

1-4. Light resistance Using a sunshine carbon arc type weather resistance tester manufactured by Iwasaki Electric Co., Ltd., a retardation film and an ultraviolet absorbing film were laminated in a combination of Tables 3 and 4 (lamination prepared by “4” described later). A light resistance test was carried out by irradiating light from the ultraviolet absorbing film side of the body for 140 hours. After completion of the light resistance test, the retardation film was taken out, and the in-plane retardation was measured in the same manner as in 1-1.
Re ₂ (550) / Re ₁ (550), where the in-plane retardation at a wavelength of 550 nm before the light resistance test is Re ₁ (550), and the in-plane retardation at a wavelength of 550 nm after the light resistance test is Re ₂ (550). Was calculated.
As a result, those having Re ₂ (550) / Re ₁ (550) of 0.92 or more and less than 1.0 are “A”, and those of Re ₂ (550) / Re ₁ (550) are 0.86 or more and less than 0.92. "B" _ones, and the _{Re 2 (550) / Re 1} (550) that is less than 0 or 0.86 to as "C". The results are shown in Tables 3 and 4.

1-5. Thickness of Retardation Layer “A” indicates that the thickness of the retardation layer is 5 μm or less, and “C” indicates that the thickness of the retardation layer exceeds 5 μm. The results are shown in Tables 3 and 4.

1-6. Image tint The display panels of Examples and Comparative Examples were incorporated into an organic EL display device to display an image, and the color of the image was visually evaluated from the front and oblique directions. "A" indicates that the yellowish color is not worrisome, "B" indicates that the color is unacceptable but has an acceptable level, and "C" indicates that the yellowish color is unacceptable. The results are shown in Tables 3 and 4.

2. 2. Production of retardation film 2-1. Retardation film 1
An alignment film forming composition (solid content: 4%, diluted with propylene glycol monomethyl ether) containing a polycinnamate-based compound was applied on a PET film having a thickness of 80 μm to form a coating film. The obtained coating film was dried at 120 ° C. for 1 minute and irradiated with polarized light at 20 mJ / cm ² (310 nm) to form an alignment film having a thickness of 200 nm.
Next, a phase difference layer (B) forming composition having the following composition is applied on the alignment film with a bar coater so that the film thickness after drying becomes 2.0 μm, dried, and cured. The laminate i provided with the phase difference layer (B) was obtained. The drying conditions were a temperature of 120 ° C. and a time of 60 seconds. Curing conditions (ultraviolet irradiation amount) were set to 200 mJ / cm ² .
Next, a pressure-sensitive adhesive layer-side surface of a pressure-sensitive adhesive sheet having an optically isotropic acrylic pressure-sensitive adhesive layer (thickness: 25 μm) on a TAC film having optical isotropy (saponified product, thickness: 80 μm); The laminate i was bonded to the surface on the side of the retardation layer (B) to obtain a laminate ii.
Next, the PET film and the alignment film of the laminate ii were peeled off to obtain a retardation film 1 having a TAC, an adhesive layer, and a retardation layer (B) in this order.
<Composition for forming retardation layer (B)>
15% by mass of compound X (a compound containing a structural unit derived from a rod-shaped polymerized liquid crystal compound and a structural unit derived from a polymerizable compound having reverse dispersion properties) described in paragraph 0351 of Japanese Patent No. 6055569; A polymerizable liquid crystal composition containing 5% by mass of a photopolymerization initiator (trade name: Irgacure 369, manufactured by BASF) and 0.4% by mass of a fluorine-based surfactant (trade name: Megafac F477, manufactured by DIC).

2-2. Retardation film 2-7
The retardation films 2 to 7 were obtained in the same manner as the retardation film 1 except that the liquid crystal compound 1 was changed to the following liquid crystal compounds 2 to 7. Each of the liquid crystal compounds 2 to 7 is a compound containing a structural unit derived from a rod-shaped polymerized liquid crystal compound and a structural unit derived from a polymerizable compound having reverse dispersion characteristics.
Liquid crystal compound 2: Liquid crystal compound having the structure of compound 7-1 described in paragraph 0250 of JP-A-2011-162678 Liquid crystal compound 3: Liquid crystal compound of Example 11 described in Patent No. 6055569 Liquid crystal compound 4 Liquid crystal compound of mixture 5 described in paragraph 0171 of Patent No. 5670179 Liquid crystal compound 5: Liquid crystal compound of Example 16 described in Patent No. 6055569 Liquid crystal compound 6: Described in Patent No. 6055569 Liquid crystal compound of Example 18 Liquid crystal compound 7: Liquid crystal compound having a structure described in (1-47-1) described in Example 4 of JP-A-2006-56106.

2-3. Retardation film 8
As the retardation film 8, a retardation film made of a commercially available aromatic polycarbonate was prepared.

3. Preparation and preparation of ultraviolet absorbing layer (C) 3-1. UV absorbing layer 1
A TAC film having a thickness of 60 μm and having optical isotropy was used as the ultraviolet absorbing layer 1.

3-2. UV absorbing layer 2-4
(Adjustment of Composition 1 for Resin Layer)
A 200 mL four-necked flask was equipped with a ball condenser, a mercury thermometer, and a stirrer, and 6- [5- (2-hydroxyethyl) -2H-benzotriazol-2-yl] benzo [1,3] dioxole-5 was added. 4.0 g (0.013 mol) of all, 40 mL of toluene, 1.8 g (0.021 mol) of methacrylic acid, and 0.4 g (0.004 mol) of methanesulfonic acid were added thereto at 110 to 115 ° C. for 4 hours. It was dehydrated under reflux. Next, 30 mL of water and 0.6 g (0.006 mol) of sodium carbonate were added, and the mixture was allowed to stand, and the lower aqueous layer was separated and removed, and 0.2 g of activated carbon was added. Then, after filtration, 40 mL of toluene was recovered from the filtrate under reduced pressure, 100 mL of isopropyl alcohol was added, and the precipitated crystals were filtered, washed with 40 mL of isopropyl alcohol, and dried at 40 ° C. under reduced pressure to remove yellow crystals. 0.2 g was obtained. 4.2 g of the yellow crystals were repulped and washed with isopropyl alcohol, and dried at 40 ° C. under reduced pressure to obtain 3.4 g of 2- [2- (6-hydroxybenzo [1,3]) as a sesamol-type benzotriazole compound. Dioxol-5-yl) -2H-benzotriazol-5-yl] ethyl methacrylate was obtained.

  Then, a four-necked flask was equipped with a Dimroth condenser, a mercury temperature clock, a nitrogen gas blowing tube, and a stirrer, and the synthesized 2- [2- (6-hydroxybenzo [1,3] dioxol-5-yl) -2H was synthesized. -Benzotriazol-5-yl] ethyl methacrylate (8 parts by mass), methyl methacrylate (MMA) as another monomer 32 parts by mass, toluene 20 parts by mass, methyl ethyl ketone 20 parts by mass, and a polymerization initiator 0.6 parts by mass of 1,1′-azobis (cyclohexane-1-carbonitrile) was added, and while stirring, the inside of the flask was replaced with nitrogen at a nitrogen gas flow rate of 10 mL / min for 1 hour. The polymerization reaction was carried out at a temperature of 100 ° C. for 10 hours under reflux.

  After completion of the polymerization reaction, 10 parts by mass of toluene and 10 parts by mass of methyl ethyl ketone (MEK) were added, and 100.6 parts by mass of a solution containing acrylic polymer 1 (light absorber 1) in which a sesamol-type benzotriazole-based compound was reactively bonded to MMA Got a part.

  A polyfunctional monomer (product name “KAYARAD PET-30”, manufactured by Nippon Kayaku Co., Ltd.) and the above-mentioned acrylic polymer 1 are mixed at a solid content mass ratio of 20:80, and the solvent (methyl ethyl ketone and toluene mass ratio up to 25% solid content) 80:20) to prepare a resin composition.

  Next, 4 parts by mass of a polymerization initiator (a mass ratio of 50:50 of Omnirad 184 and Omnirad 819 manufactured by IGM Resins BV) to 160 parts by mass of the obtained resin composition, and a leveling agent (product name “F568”) And DIC Co., Ltd.) in an amount of 0.2 part by mass, and the mixture was thoroughly stirred to prepare a composition 1 for a resin layer.

(Preparation of composition 2 for resin layer)
A polyfunctional monomer (product name “KAYARAD PET-30”, manufactured by Nippon Kayaku Co., Ltd.) is diluted with a solvent (methyl ethyl ketone and methyl isobutyl ketone, mass ratio 50:50) to a solid content of 50% to obtain a resin composition. It was adjusted.

  Next, based on 200 parts by mass of the obtained resin composition, 4 parts by mass of a polymerization initiator (Omnirad 184 manufactured by IGM Resins BV) and a leveling agent (product name “F568”, manufactured by DIC Corporation) were added. The mixture was mixed with 2 parts by mass, and the mixture was sufficiently stirred to prepare a composition 2 for a resin layer.

The obtained composition 1 for a resin layer was applied to the surface of a 25 μm-thick triacetylcellulose substrate (product name “TJ25UL”, manufactured by FUJIFILM Corporation) with a Miya bar to form a coating film. Next, the solvent in the coating film is evaporated by flowing dry air at 70 ° C. for 30 seconds at a flow rate of 0.5 m / s to the formed coating film, and the integrated amount of ultraviolet light becomes 200 mJ / cm ² . By irradiating as described above to cure the coating film, a first resin layer having a thickness of 2 μm was formed.

After forming the first resin layer, the resin layer composition 2 was applied to the surface of the first resin layer using a Meyer bar to form a coating film. Next, the solvent in the coating film is evaporated by flowing dry air at 70 ° C. for 30 seconds at a flow rate of 0.5 m / s to the formed coating film, and the integrated amount of ultraviolet light becomes 200 mJ / cm ² . By irradiating as described above to cure the coating film, a second resin layer having a thickness of 4 μm was formed. Thus, an ultraviolet absorbing layer (C) [ultraviolet absorbing layer 2] having a laminated structure of the TAC film, the resin layer containing the ultraviolet absorbing agent (first resin layer), and the second resin layer was obtained.
Further, in the same manner as above, except that the thickness of the first resin layer was changed to 3 μm, the TAC film, the resin layer containing the ultraviolet absorbent (first resin layer), and the second resin layer (C) [Ultraviolet absorbing layer 3] having the following laminated structure.
Further, in the same manner as described above, except that the thickness of the first resin layer was changed to 4 μm, the TAC film, the resin layer containing the ultraviolet absorber (first resin layer), and the second resin layer (C) [Ultraviolet absorbing layer 4] having the above laminated structure.

4. Lamination of retardation film and ultraviolet absorbing layer (C) The surface of retardation film (B) side of retardation films 1 to 8 of "2" and the TAC film of ultraviolet absorption layers 1 to 4 of "3" The two sides were laminated via an acrylic pressure-sensitive adhesive layer (thickness: 25 μm) having optical isotropy to obtain a laminate. The retardation films 1 to 8 and the ultraviolet absorbing layers 1 to 4 were combined as shown in Tables 3 and 4.

5. Preparation of Display Panel An optical member disposed on an organic EL element of a commercially available organic EL display device was taken out. A laminate was prepared by laminating a retardation film and an ultraviolet absorbing film in the combination shown in Tables 3 and 4 on the organic EL element, and a polarizing plate was further arranged on the ultraviolet absorbing layer of the laminate. And the display panel and the display device of the comparative example were obtained. In addition, it was arranged so that the angle formed between the absorption axis of the polarizer of the polarizing plate and the slow axis of the retardation layer of the retardation film was 45 degrees.

  As is clear from Tables 1 to 4, the display panel satisfying the conditions 1 to 3 can significantly suppress the temporal deterioration of the retardation layer and can suppress the temporal deterioration of the display quality. Can be confirmed.

10: Display element (A)
20: retardation layer (B)
30: UV absorbing layer (C)
100: Display panel

Claims (9)

A display having a display element (A), a retardation layer (B) arranged on the light emitting surface side of the display element, and an ultraviolet absorbing layer (C) arranged on the light emitting surface side of the retardation layer. A panel,
The retardation layer (B) comprises a liquid crystal compound, the retardation layer refractive index in the slow axis direction refractive index is largest and the direction in the plane n _x of _(B), the retardation layer (B) When the refractive index in the fast axis direction, which is the direction orthogonal to the slow axis direction, is ny and the refractive index in the thickness direction of the retardation layer (B) is _nz , the following condition 1 is _satisfied . A display panel that satisfies ~ 3.
<Condition 1>
_{n x>} n _y ≒ n _z, or _{n x} ≒ n z> n _y
<Condition 2>
Linearly polarized light ₁ whose vibration direction is parallel to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), and the phase difference layer (B) Let t ₁ be the spectral transmission spectrum of the linearly polarized light ₁ transmitted through. The linearly polarized light ₁ is horizontal polarized light or vertical polarized light.
Also, linearly polarized light ₂ whose vibration direction is perpendicular to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), B) transmitted through the spectral transmission spectrum of the linearly polarized light ₂ and t _2. When the linearly polarized light ₁ is horizontal polarized light, the linearly polarized light ₂ is vertical polarized light, and when the linearly polarized light ₁ is vertical polarized light, the linearly polarized light ₂ is horizontal polarized light.
t ₁ and t ₂ each have an absorption spectrum in which the transmittance decreases in the wavelength range of 300 to 450 nm toward the shorter wavelength, and the transmission start wavelength of t ₁ is a ₁ (nm) and the transmission of t ₂ When the starting wavelength is a ₂ (nm), the relationship a ₁ ≠ a ₂ is satisfied.
<Condition 3>
From a direction perpendicular to the plane of the ultraviolet absorbing layer (C), incident unpolarized light, a transmission start wavelength based on the spectral transmission spectrum t ₃ of the light transmitted the ultraviolet absorbing layer (C) a ₃ (nm), the following expressions (1) to (3) are satisfied.
a ₁ <a ₃ (1)
a ₂ <a ₃ (2)
a ₃ ≦ 420 nm (3) The display panel according to claim 1, further satisfying the following condition 4:
<Condition 4>
as the wavelength of a ₁ and _{a 2} is large, the difference between _{a 3} or more 2nm The in-plane retardation of the retardation layer (B) at a wavelength of 450 nm is Re (450), the in-plane retardation of the retardation layer (B) at a wavelength of 550 nm is Re (550), and the in-plane retardation of the retardation layer (B) is The display panel according to claim 1, wherein the following formula (i) is satisfied when the in-plane retardation at a wavelength of 650 nm is Re (650).
Re (450) <Re (550) <Re (650) (i) The display panel according to claim 3, further satisfying the following expression (ii).
0.75 ≦ Re (450) / Re (550) ≦ 0.98 (ii) The display panel according to any one of claims 1 to 4, wherein the retardation layer (B) satisfies the following expression (iii).
80 nm ≦ Re (550) ≦ 220 nm (iii)   The display panel according to any one of claims 1 to 5, wherein the ultraviolet absorbing layer (C) has a laminated structure of a transparent base material and a resin layer containing an ultraviolet absorbing agent.   The display panel according to any one of claims 1 to 6, wherein the display element is an organic EL element or a micro LED element.   An image display device comprising the display panel according to claim 1. A display having a display element (A), a retardation layer (B) arranged on the light emitting surface side of the display element, and an ultraviolet absorbing layer (C) arranged on the light emitting surface side of the retardation layer. In the panel,
The retardation layer (B) comprises a liquid crystal compound, the retardation layer refractive index in the slow axis direction refractive index is largest and the direction in the plane n _x of _(B), the retardation layer (B) the refractive index n _y in the fast axis direction is a direction perpendicular to the slow axis direction in the _plane, the refractive index in the thickness direction of the retardation layer (B) upon the n _z of
A method for selecting an ultraviolet absorbing layer of a display panel, wherein the ultraviolet absorbing layer (C) is selected so as to satisfy the following conditions 1 ′ to 2 ′.
<Condition 1 '>
_{n x>} n _y ≒ n _z, or _{n x} ≒ n z> n _y
<Condition 2 '>
Linearly polarized light ₁ whose vibration direction is parallel to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), and the phase difference layer (B) Let t ₁ be the spectral transmission spectrum of the linearly polarized light ₁ transmitted through. The linearly polarized light ₁ is horizontal polarized light or vertical polarized light.
Also, linearly polarized light ₂ whose vibration direction is perpendicular to the direction of the slow axis of the phase difference layer (B) is incident from a direction perpendicular to the plane of the phase difference layer (B), B) transmitted through the spectral transmission spectrum of the linearly polarized light ₂ and t _2. When the linearly polarized light ₁ is horizontal polarized light, the linearly polarized light ₂ is vertical polarized light, and when the linearly polarized light ₁ is vertical polarized light, the linearly polarized light ₂ is horizontal polarized light.
t ₁ and t ₂ each have an absorption spectrum in which the transmittance decreases in the wavelength range of 300 to 450 nm toward the shorter wavelength, and the transmission start wavelength of t ₁ is a ₁ (nm) and the transmission of t ₂ The starting wavelength is a ₂ (nm). Further, from the direction perpendicular to the plane of the ultraviolet absorbing layer (C), incident unpolarized light, transmission start wavelength based on the spectral transmission spectrum t ₃ of the light transmitted the ultraviolet absorbing layer (C) Is a ₃ (nm).
Under the above preconditions, the following expressions (1 ′) and (2 ′) are satisfied.
a ₁ ≠ a ₂ <a ₃ (1 ′)
a ₃ ≦ 420 nm (2 ′)