JP7351621B2 - Circular polarizers and optical display devices - Google Patents

Description

The present invention relates to circularly polarizing plates and optical display devices.

Conventionally, circularly polarizing plates have been used as optical films for suppressing reflection of external light in display devices (see, for example, Patent Document 1). Such an optical film is known as a so-called antireflection film. The circularly polarizing plate has a polarizer provided on the light incidence side and a retardation layer (λ/4 plate) provided on the opposite side of the light incidence side with respect to the polarizer.

The circularly polarizing plate suppresses reflection of external light in the following manner.
First, external light incident on the circularly polarizing plate is converted into linearly polarized light by the polarizer, and then converted into circularly polarized light by the retardation layer. After the circularly polarized light reaches a display device provided with a circularly polarizing plate, it is reflected at a fixed end on the surface of the display device, thereby being reflected with a phase shift of λ/2.

Thereafter, the reflected circularly polarized light enters the retardation layer again and is converted into linearly polarized light. At this time, due to the fixed end reflection of the circularly polarized light, the linearly polarized light to be converted has a relationship in which the plane of vibration is perpendicular to the linearly polarized light that has passed through the polarizer and is converted from outside light. As a result, external light reflected on the surface of the display device cannot pass through the polarizer and is absorbed or reflected by the polarizer without being emitted to the outside. In this way, the circularly polarizing plate suppresses reflection of external light.

Japanese Patent Application Publication No. 2014-170221

The retardation value of the retardation layer differs depending on the wavelength of light. Therefore, even if the retardation layer is the same, the performance of the retardation layer differs depending on the wavelength of light. For example, a retardation layer that can satisfactorily convert linearly polarized light having a wavelength near green into circularly polarized light has a problem in that it cannot satisfactorily convert linearly polarized light having a wavelength near red or blue into circularly polarized light.

In the design of circularly polarizing plates whose main purpose is to suppress reflection of external light, a retardation layer is often used to convert light in the vicinity of green, which has high visibility, into ideal circularly polarized light. A circularly polarizing plate designed in this way can easily reduce glare from outside light. On the other hand, in such a circularly polarizing plate, the reflection of light having wavelengths near red or blue tends to be insufficiently suppressed, and the reflected light tends to be colored.

Therefore, when a conventional circularly polarizing plate is used as an antireflection plate as described above, the image quality may deteriorate due to colored reflected light. Therefore, there has been a need for a circularly polarizing plate that suppresses the coloring of reflected light.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a circularly polarizing plate that suppresses coloring of reflected light. Another object of the present invention is to provide an optical display device that includes such a circularly polarizing plate and is capable of displaying good images.

In order to solve the above problems, one embodiment of the present invention includes a polarizer layer, a retardation layer, and a light absorption layer, and the retardation layer has an in-plane retardation value for light with a wavelength of λ nm. When Re(λ), the following formulas (1) and (2) are satisfied, the light absorption layer has a base material layer and a dye dispersed in the base material layer, and the dye has a wavelength of 390 A circularly polarizing plate having a maximum absorption wavelength in a wavelength band of ~430 nm is provided.
0.80<Re(450)/Re(550)<1.00...(1)
1.00<Re(650)/Re(550)<1.30...(2)

In one aspect of the present invention, the transmittance Ta (λ) of the circularly polarizing plate for light having a wavelength of λ nm may satisfy the following formulas (3) to (5).
Ta(390)<4%...(3)
Ta(410)<38%...(4)
Ta(430)<42%...(5)

In one aspect of the present invention, the base layer may be a pressure-sensitive adhesive layer or an adhesive layer.

In one aspect of the present invention, the transmittance Tb(λ) of the light absorption layer for light having a wavelength of λnm may satisfy the following formulas (i) to (iii).
Tb(390)≦85%…(i)
Tb(410)≦98%…(ii)
Tb(430)≦99%…(iii)

Further, one aspect of the present invention provides an optical display device including an optical display panel and the above circularly polarizing plate bonded to a display surface of the optical display panel.

In one aspect of the present invention, the circularly polarizing plate is arranged such that the polarizer layer is on a side opposite to the optical display panel with respect to the retardation layer, and the polarizer layer of the circularly polarizing plate A configuration may also be adopted in which a front plate is provided on the side.

In one aspect of the present invention, a touch sensor may be provided between the display surface and the circularly polarizing plate.

According to the present invention, it is possible to provide a circularly polarizing plate in which coloring of reflected light is suppressed. Furthermore, it is possible to provide an optical display device that includes such a circularly polarizing plate and is capable of displaying good images.

1 is a cross-sectional view showing the configuration of an optical display device 10 including a circularly polarizing plate 1 and an optical display panel 20. FIG. FIG. 3 is an explanatory diagram illustrating the design concept of a retardation layer 3. FIG. It is an explanatory view showing a modification of an optical display device.

Hereinafter, a circularly polarizing plate according to this embodiment will be explained with reference to the drawings. Note that in all the drawings below, the dimensions and ratios of each component are changed as appropriate to make the drawings easier to read.

[Definition of terms and symbols]
Definitions of terms and symbols used herein are as follows.
(1) Refractive index (nx, ny, nz)
“nx” is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction).
"ny" is the refractive index in the direction perpendicular to the slow axis within the plane.
"nz" is the refractive index in the thickness direction.

(2) In-plane retardation value The in-plane retardation value (Re(λ)) refers to the in-plane retardation value of the film at 23° C. and wavelength λ (nm). Re(λ) is determined by Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the film.
Here, nx, ny, and nz used in the calculation of Re(λ) are values measured using light of wavelength λ (nm) at 23°C. d is a value measured at 23°C.
In the following description, an in-plane phase difference value may be referred to as an "in-plane phase difference value."

(3) Retardation value in the thickness direction The in-plane retardation value (Rth (λ)) refers to the retardation value in the thickness direction of the film at 23° C. and wavelength λ (nm). Rth(λ) is determined by Rth(λ)=((nx+ny)/2−nz)×d, where d (nm) is the thickness of the film.
Here, nx, ny, and nz used in the calculation of Rth (λ) are values measured at 23° C. using light of wavelength λ (nm). d is a value measured at 23°C.

(4) Nz coefficient The Nz coefficient is a value determined by Nz coefficient=Rth(λ)/Re(λ)+0.5.

[Circularly polarizing plate, optical display device]
FIG. 1 is a cross-sectional view showing the configuration of an optical display device 10 including a circularly polarizing plate 1 and an optical display panel 20 of this embodiment.

As shown in FIG. 1, the circularly polarizing plate 1 includes a polarizer layer 2 and a retardation layer 3 disposed on one side of the polarizer layer 2. Further, protective films 5 and 6 are arranged on both sides of the polarizer layer 2, respectively.

A retardation layer 3 is laminated on one side of the polarizer layer 2 with a light absorption layer 7 in between. On the surface of the retardation layer 3 opposite to the polarizer layer 2, an adhesive layer 8 for laminating on an optical display panel 20, which will be described later, is arranged. Note that a release film (not shown) is attached to the surface of the adhesive layer 8 before use. Further, the adhesive layer 8 is formed of, for example, an acrylic adhesive.

(Polarizer layer)
The polarizer layer 2 allows linearly polarized light having a plane of polarization in a specific direction to pass therethrough. The light that has passed through the polarizer layer 2 becomes linearly polarized light that vibrates in the direction of the transmission axis of the polarizer. The thickness of the polarizer layer 2 is, for example, about 1 μm to 80 μm.

As the polarizer layer 2, for example, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a partially saponified ethylene/vinyl acetate copolymer film is coated with iodine, dichroic dye, etc. Those that have been dyed with a dichroic substance and stretched can be used. Further, as the polarizer layer 2, a polyene-based oriented film such as a dehydrated polyvinyl alcohol or a dehydrochloric acid treated polyvinyl chloride can be used. Among these, the polarizer layer 2 obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it is preferable because it has excellent optical properties.

Staining with iodine is performed, for example, by immersing a polyvinyl alcohol film in an aqueous iodine solution. The stretching ratio for uniaxial stretching is preferably 3 to 7 times. Stretching may be carried out after the dyeing treatment or may be carried out while dyeing. Alternatively, it may be dyed after being stretched.

The polyvinyl alcohol film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. as necessary. For example, by immersing a polyvinyl alcohol film in water and washing it with water before dyeing, you can not only clean dirt and anti-blocking agents from the surface of the polyvinyl alcohol film, but also swell the polyvinyl alcohol film and dye it. It is possible to prevent unevenness.

As the polarizer layer 2, for example, as described in JP-A-2016-170368, a cured film in which a liquid crystal compound is polymerized and dichroic dyes are oriented may be used. As the dichroic dye, one having absorption within the wavelength range of 380 to 800 nm can be used, and it is preferable to use an organic dye. Examples of dichroic dyes include azo compounds. The liquid crystal compound is a liquid crystal compound that can be polymerized while being oriented, and can have a polymerizable group in the molecule.

The visibility correction polarization degree of the polarizer layer 2 is preferably 95% or more, more preferably 97% or more. Further, it may be 99% or more, or 99.9% or more. The visibility correction polarization degree of the polarizer layer 2 may be 99.995% or less, or may be 99.99% or less.

Here, the "visibility correction polarization degree" of the polarizer layer 2 is a value obtained by correcting the polarization degree of the polarizer layer 2 for light with a wavelength λnm by the visibility of light with a wavelength λnm. Hereinafter, the "visual sensitivity correction degree of polarization" may be simply referred to as the "correction degree of polarization."

The corrected degree of polarization is calculated using a spectrophotometer with an integrating sphere (“V7100” manufactured by JASCO Corporation), and the luminous sensitivity is determined by the 2-degree field of view (C light source) of “JIS Z 8701” for the obtained degree of polarization. It can be calculated by performing correction.

If the corrected polarization degree of the polarizer layer 2 is less than 95%, it may not be able to function as an antireflection film.

The visibility-corrected single transmittance of the polarizer layer 2 is preferably 40% or more, more preferably 42% or more. Further, the visibility correction single transmittance of the polarizer layer 2 is preferably 50% or less, more preferably 45% or less. In a circularly polarizing plate including a polarizer layer with high transmittance, it is easy to visually recognize the coloring of reflected light, which is an issue in the present application. Therefore, a circularly polarizing plate equipped with a polarizer layer with high transmittance and to which the present invention is applied suppresses the coloring of reflected light, compared to a circularly polarizing plate equipped with a polarizer layer with high transmittance and to which the present invention is not applied. A high quality circularly polarizing plate can be obtained.

Here, the "visibility corrected single transmittance" of the object is a value obtained by correcting the transmittance of the object for light with a wavelength of λ nm by the visibility of light with a wavelength of λ nm. Hereinafter, the "visual sensitivity correction single transmittance" may be simply referred to as "corrected transmittance."

For the corrected transmittance, use a spectrophotometer with an integrating sphere (“V7100” manufactured by JASCO Corporation), and perform visibility correction on the obtained transmittance using JIS Z 8701 2 degree field of view (C light source). It can be calculated by

A polarizer layer 2 with a corrected transmittance exceeding 50% may not be able to function as an antireflection film because the degree of polarization is too low.

(phase difference layer)
The retardation layer 3 can be a positive A plate that functions as a quarter wavelength plate (λ/4 plate).

The retardation layer 3 satisfies nx>ny, where nx is the refractive index in the slow axis direction in the plane, ny is the refractive index in the fast axis direction in the plane, and nz is the refractive index in the thickness direction. satisfy the relationship. The retardation layer 3, which is a λ/4 plate, has a function of converting linearly polarized light of a certain wavelength into circularly polarized light, or converting circularly polarized light into linearly polarized light.

The retardation layer 3 exhibits any appropriate refractive index ellipsoid as long as it satisfies the relationship nx>ny. Preferably, the refractive index ellipsoid of the retardation layer 3 exhibits the relationship nx>ny≧nz. The Nz coefficient of the retardation layer 3 is preferably 1 to 2, more preferably 1 to 1.5, and even more preferably 1 to 1.3.

Further, the retardation layer 3 exhibits reverse wavelength dispersion characteristics.
In a normal resin film, the ratio of the in-plane retardation value Rg for green light and the in-plane retardation value Rb for blue light is Rb/Rg, and the in-plane retardation value Rg and the in-plane retardation value for red light are Rb/Rg. When the ratio with Rr is Rr/Rg, Rr/Rg is smaller than Rb/Rg. Hereinafter, such wavelength dispersion may be referred to as "positive" wavelength dispersion.
On the other hand, in the retardation layer 3, Rr/Rg is larger than Rb/Rg. The characteristics of such a retardation layer are referred to as "reverse" wavelength dispersion because the ratio of in-plane retardation values is reversed with respect to the optical characteristics of ordinary resin films.

The retardation layer 3 satisfies (1) and (2) below, where Re(λ) is the in-plane retardation value for light with a wavelength of λ nm.
0.80<Re(450)/Re(550)<1.00...(1)
1.00<Re(650)/Re(550)<1.30...(2)

Re(450)/Re(550) in formula (1) is a value exceeding 0.80, preferably exceeding 0.82, and Re(450)/Re(550) is less than 1.00. , is preferably 0.95 or less, more preferably 0.92 or less, particularly preferably less than 0.90, and Re(450)/Re(550) is greater than 0.80 and 0. It is preferably 95 or less, more preferably more than 0.80 and less than 0.92, even more preferably 0.82 or more and less than 0.92, and may be more than 0.80 and less than 0.90.

Re(650)/Re(550) in formula (2) is less than 1.30, preferably 1.20 or less, and more preferably 1.10 or less. Re(650)/Re(550) is preferably greater than 1.00 and less than or equal to 1.20, more preferably greater than 1.00 and less than or equal to 1.10.

Although the thickness of the retardation layer 3 is not particularly limited, it is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm. Note that the thickness of the retardation layer 3 is obtained by measuring the thickness at five arbitrary points within the plane and calculating the arithmetic average of the thicknesses.

Such wavelength dispersion characteristics of the retardation layer are due to wavelength dispersion characteristics of the liquid crystal compound that is the raw material of the retardation layer. The wavelength dispersion characteristics of a retardation layer exhibiting reverse wavelength dispersion characteristics are determined by the blending ratio of a liquid crystal compound exhibiting positive wavelength dispersion and a liquid crystal compound exhibiting reverse wavelength dispersion, and the thickness of the retardation layer. By controlling it, it can be adjusted as appropriate.
In the retardation layer of the embodiment of JP-A-2017-167517, the balance between the wavelength dispersion characteristics on the short wavelength side and the wavelength dispersion characteristics on the long wavelength side is adjusted with 550 nm as a reference.

By such adjustment, the wavelength dispersion characteristic of the retardation layer 3 approaches an ideal state on the long wavelength side (red side), and it becomes possible to suppress the reflected light from being colored red. Note that the "ideal state" is a state of retardation of the retardation layer in an ideal state in which light of any wavelength is converted into ideal circularly polarized light.
On the other hand, due to the above-described adjustment, the wavelength dispersion characteristics of the retardation layer 3 deviate from the ideal state on the short wavelength side (blue side), so that reflected light is likely to be colored blue.
In the circularly polarizing plate of this embodiment, the coloring of the reflected light that occurs in this manner is reduced by the function of the light absorption layer, which will be described later.

The retardation layer 3 can be produced by a known method.
For example, after synthesizing a polymerizable reverse wavelength dispersion liquid crystal using a known method, the reverse wavelength dispersion liquid crystal is coated on an alignment film formed on a substrate to align in one direction, and the reverse wavelength dispersion liquid crystal is polymerized. , a retardation layer 3 having reverse wavelength dispersion characteristics can be manufactured.

(Protective film)
The protective films 5 and 6 function as protective layers that protect the polarizer layer 2. In the figure, the protective films 5 and 6 are arranged on both sides of the polarizer layer 2, but the protective film 6 is omitted, and the outside of the polarizer layer 2 (the side opposite to the side facing the retardation layer 3) ) may be provided with only the protective film 5 disposed in the area. Further, a protective film 6 may be disposed on the inner surface of the polarizer layer 2 (the surface facing the retardation layer 3).

As the material for the protective films 5 and 6, for example, a translucent thermoplastic resin can be used. The protective films 5 and 6 are made of, for example, a chain polyolefin resin such as a polypropylene resin, a polyolefin resin such as a cyclic polyolefin resin, a cellulose ester resin such as cellulose triacetate or cellulose diacetate, a polyester resin, or a polycarbonate. type resin, (meth)acrylic resin, polystyrene resin, etc. can be used as the forming material. Examples of the cyclic polyolefin resin include norbornene resin. A mixture or copolymer of these materials may also be used.

Moreover, the protective films 5 and 6 may be protective films having optical functions such as a retardation layer or a brightness enhancement film. For example, by uniaxially or biaxially stretching a film made of the above-mentioned thermoplastic resin, or by forming a liquid crystal layer or the like on the film, a retardation layer with an arbitrary retardation value can be obtained. can.
In this case, the above-mentioned retardation layer 3 can also serve as the protective film 6.

The total thickness of the protective films 5 and 6 is preferably 5 μm to 200 μm, more preferably 5 μm to 100 μm, and still more preferably 10 μm to 95 μm. The protective films 5 and 6 have a total in-plane retardation value Re (550) of, for example, 0 nm to 10 nm or 70 nm to 140 nm, and a total thickness direction retardation value Rth (550) of, for example, -80 nm to +80 nm. .

The protective film 5 may be subjected to a surface treatment such as hard coat treatment, antireflection treatment, antisticking treatment, or antiglare treatment as necessary on the surface opposite to the side facing the polarizer layer 2. good. The thickness of the surface treatment layer is 500 μm or less, preferably 150 μm or less, more preferably 1 μm to 20 μm, and still more preferably 2 μm to 10 μm.

Further, when the circularly polarizing plate 1 of this embodiment is arranged on the display surface of a passive stereoscopic display device using circularly polarized light, the circularly polarizing plate 1 is placed opposite to the polarizer layer 2 of the protective film 5. A λ/4 plate may be provided on the surface opposite to the side.

It is preferable that the protective film 6 is optically isotropic. That is, "optically isotropic" means that the in-plane retardation value Re (550) is 0 nm to 10 nm and the thickness direction retardation value Rth (550) is -10 nm to +10 nm. means. The thickness of the protective film 6 in this case is preferably 2 μm to 200 μm, more preferably 5 μm to 100 μm.

(light absorption layer)
The light absorption layer 7 has a base material layer and a dye dispersed in the base material layer.

The base material layer may be an active energy ray-curable adhesive containing a curable compound that is cured by irradiation with active energy rays, or a water-based adhesive in which an adhesive component such as polyvinyl alcohol resin is dissolved or dispersed in water. It may also be used as a forming material. In this case, the light absorption layer 7 functions as an adhesive layer.

Examples of the active energy that initiates the curing reaction of the active energy ray-curable adhesive include ultraviolet rays, visible light, electron beams, and X-rays. The active energy ray curable adhesive is preferably an ultraviolet ray curable adhesive.

Since the active energy ray curable adhesive exhibits good adhesive properties, it is an active energy ray curable adhesive composition containing either or both of a cationic polymerizable curable compound and a radically polymerizable curable compound. is preferred. The active energy ray-curable adhesive can further include one or both of a cationic polymerization initiator and a radical polymerization initiator for initiating a curing reaction.

Examples of cationically polymerizable curable compounds include epoxy compounds having one or more epoxy groups in the molecule, and oxetane compounds having one or more oxetane rings in the molecule. I can do it.

Examples of radically polymerizable curable compounds include (meth)acrylic compounds having one or more (meth)acryloyloxy groups in the molecule, and other vinyl compounds having radically polymerizable double bonds. Examples include type compounds.

Active energy ray-curable adhesives may contain cationic polymerization accelerators, ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, fluidity regulators, plasticizers, and erasers, as necessary. It may contain additives such as foaming agents, antistatic agents, leveling agents, and solvents.

The dye dispersed in the base material layer of the light absorption layer 7 has a maximum absorption wavelength in a wavelength band of 390 to 430 nm, which is the short wavelength band of visible light. Here, in this embodiment, "visible light" is light with a wavelength within the range of 390 nm to 830 nm.

Examples of such dyes include KEMISORB 111, KEMISORB 73 (all manufactured by ChemiPro Kasei Co., Ltd.), and SUMISORB 300 (manufactured by Sumika Chemtex Co., Ltd.).

In addition, a compound having a maximum absorption wavelength in the wavelength range of 390 to 430 nm can be synthesized by a known method and used as the dye of this embodiment. As such a dye, for example, a compound known as a light-selective absorbing compound described in JP-A No. 2017-120430 can be used.

When the light absorption layer 7 functions as an adhesive layer, the thickness of the light absorption layer 7 is preferably 0.5 to 5 μm, more preferably 0.5 to 3 μm.

In such a light absorption layer 7, the dye dispersed within the base material layer absorbs blue light. Therefore, the bluish tinge of the light emitted through the circularly polarizing plate 1 can be reduced.

In addition, for the base material layer, an adhesive is appropriately selected as a forming material that exhibits adhesive performance to the extent that peeling does not occur in a high temperature environment, a moist heat environment, or an environment where high and low temperatures are repeated to which the polarizing plate is exposed. You may. In this case, the light absorption layer 7 functions as an adhesive layer.

Examples of the material for forming the base layer include commonly known acrylic adhesives, silicone adhesives, rubber adhesives, and the like. Among these, acrylic adhesives are particularly preferred because they have high transparency, weather resistance, excellent heat resistance, and are easy to process.

The adhesive may contain tackifiers, plasticizers, fillers such as glass fibers, glass beads, metal powders, and other inorganic powders, pigments, colorants, fillers, antioxidants, and ultraviolet absorbers as necessary. , an antistatic agent, a silane coupling agent, and other various additives may be appropriately blended.

The light absorption layer 7, which is an adhesive layer, is usually formed by applying an adhesive solution onto a release sheet and drying it. For coating onto the release sheet, for example, roll coating methods such as reverse coating and gravure coating, spin coating methods, screen coating methods, fountain coating methods, dipping methods, spray methods, etc. can be adopted. A release sheet provided with an adhesive layer is used by a method of transferring the same.

The thickness of the light absorption layer 7, which is an adhesive layer, is usually about 3 to 100 μm, preferably 5 to 50 μm.

The amount of blue light absorbed by the light absorption layer 7 can be controlled by adjusting the type of dye, the amount of dye contained in the light absorption layer 7, and the thickness of the light absorption layer 7. When the amount of dye contained in the light absorption layer 7 is increased, the amount of blue light absorbed by the light absorption layer 7 tends to increase. Furthermore, when the thickness of the light absorption layer 7 is increased, the amount of blue light absorbed by the light absorption layer 7 tends to increase.

It is preferable that the light absorption layer 7 has a transmittance Tb (λ) that satisfies the following (i) to (iii).
Tb(390)≦85%…(i)
Tb(410)≦98%…(ii)
Tb(430)≦99%…(iii)

Tb(390) is preferably 40% or less, more preferably 1% or less.
Tb(410) is preferably 50% or less, more preferably 10% or less.
Tb(430) is preferably 90% or less, more preferably 88% or less.

In this embodiment, the transmittance of the light absorption layer 7 employs a value measured by the following method.
One side of the light-absorbing layer is laminated to alkali-free glass (manufactured by Corning Inc., product name "Eagle , trade name "ZF-14-23"). Next, the transmittance of the obtained laminate at 390 nm, 410 nm, and 430 nm is measured using a spectrophotometer with an integrating sphere ("V7100" manufactured by JASCO Corporation), and the obtained value is determined as the desired transmittance Tb. (390), Tb (410), and Tb (430). Note that the measured value is a value that removes the influence of interface reflection.

(Circularly polarizing plate)
It is preferable that the transmittance Ta (λ) of such a circularly polarizing plate 1 satisfies the following (3) to (5).
Ta(390)<4%...(3)
Ta(410)<38%...(4)
Ta(430)<42%...(5)

In this embodiment, the transmittance of the circularly polarizing plate 1 employs a value measured by the following method.
A circularly polarizing plate was laminated to alkali-free glass (manufactured by Corning Corporation, product name "Eagle The transmittance of the circularly polarizing plate 1 is determined by measuring the obtained laminate using an ultraviolet-visible near-infrared spectrophotometer (manufactured by JASCO Corporation, trade name "V-7100").

As described above, in the circularly polarizing plate 1, a reverse wavelength dispersion type retardation layer with adjusted optical properties is used as the retardation layer 3. Therefore, in the circularly polarizing plate 1, the leakage of red light is reduced and the leakage of blue light is increased. That is, considering the configuration of the retardation layer 3, the circularly polarizing plate 1 has a configuration in which reflected light is likely to be colored blue.

Here, the circularly polarizing plate 1 has a structure in which the light absorption layer 7 can satisfactorily absorb blue light.
Therefore, in the circularly polarizing plate 1, the light absorption layer 7 can satisfactorily absorb the blue light contained in the reflected light, and it is possible to suppress coloring of the reflected light.

(Optical display panel)
Examples of the optical display panel 20 include a liquid crystal display device and an organic EL panel. As the liquid crystal display device and the organic EL panel, those having generally known configurations can be used.

As shown in FIG. 1, the above-described circularly polarizing plate 1 is bonded to the display surface of an optical display panel 20 to constitute an optical display device 10. By providing the circularly polarizing plate 1 on the display surface, the optical display device 10 suppresses reflection of external light and suppresses coloring of the reflected light.

According to the circularly polarizing plate 1 having the above configuration, the circularly polarizing plate suppresses coloring of reflected light.

Moreover, according to the optical display device 10 configured as described above, it is possible to display a good image.

Although the circularly polarizing plate 1 of this embodiment has the retardation layer 3 which is a positive A plate, a positive C plate may also be used.

A positive C plate satisfies the relationship nz>nx≧ny. The difference between the value of nx and the value of ny is preferably within 0.5% of the value of ny, and more preferably within 0.3%. If it is within 0.5%, it can be substantially considered that nx=ny.

It is preferable that the retardation value Rth (λ) of the positive C plate in the thickness direction at the wavelength λnm satisfies the relationship -300nm≦Rth(550)≦-20nm, and -150nm≦Rth(550)≦-20nm. It is more preferable to satisfy the following relationship.

Such a positive C plate is preferably provided between the polarizer layer 2 and the optical display panel 20.

Furthermore, in this embodiment, the dye is dispersed in the adhesive layer or pressure-sensitive adhesive layer that integrates the polarizer layer 2 and the retardation layer 3, and functions as the light absorption layer 7, but the invention is not limited thereto. .

The dye that absorbs blue light may be dispersed in other layers as long as it does not impair the effects of the invention. For example, if the above-mentioned dye is mixed into the adhesive layer 8, the adhesive layer 8 becomes the light absorption layer in the present invention.

Further, a dye may be dispersed in the protective films 5 and 6 to function as a light absorption layer.
In this case, the base material layer included in the light absorption layer can be a film made of thermoplastic resin. The light absorption layer having such a base layer may be any film disposed on the viewing side of the display element, such as a protective film.

The light-absorbing layer is preferably a light-absorbing layer in which a pressure-sensitive adhesive layer or an adhesive layer that can be produced under relatively mild conditions is used as a base layer, and a dye is dispersed in the base layer.

The number of light absorption layers may be one, or two or more layers may be provided.

FIG. 3 is an explanatory diagram showing a modification of the optical display device.
The optical display device 100 includes a circularly polarizing plate 30 with a front plate, a touch sensor 40, and an optical display panel 20. As shown in FIG. 3, in the optical display device 100, the circularly polarizing plate 30 with a front plate, the touch sensor 40, and the optical display panel 20 can be stacked on each other.

In the optical display device 100, the polarizer layer 2 of the circularly polarizing plate 1 is disposed on the outside, that is, on the opposite side from the optical display panel 20, and the retardation layer 3 is disposed on the optical display panel 20 side. In other words, in the optical display device 100, the circularly polarizing plate 1 is arranged such that the retardation layer 3 is located between the polarizer layer 2 and the optical display panel 20.

The circularly polarizing plate 30 with a front plate includes the above-described circularly polarizing plate 1 and a front plate (window film) 35 provided in contact with the protective film 5 that the circularly polarizing plate 1 has. That is, the circularly polarizing plate 30 with a front plate has a structure in which the front plate (window film) 35 and the circularly polarizing plate 1 are laminated. This polarizing plate 30 with a front plate has a front plate 35 on the polarizer layer 2 side that constitutes the circularly polarizing plate 1 .

(Front plate)
The front plate 35 includes a transparent base material 31 and a hard coat layer 32 formed on at least one surface of the transparent base material 31. The front plate 35 has the function of protecting the optical display panel 20 and other components of the optical display device 10 from external impact and internal stress caused by changes in temperature and humidity. The front plate 35 shown in FIG. 3 is provided with the transparent base material 31 side in contact with the protective film 5.

As the transparent base material 31, various materials can be used as long as it is a flexible resin film having light transmittance. In addition, in this specification, "transparent" means that the transmittance of visible light is 70% or more, or 80% or more.

As the transparent base material 31, unstretched films, uniaxially stretched films, or biaxially stretched films of various transparent resins can be used. The transparent resin constituting the transparent base material 31 may be used alone or in a mixture of two or more.

As such a transparent base material 31, specifically, a polyamide-imide film, a polyimide film, a stretched polyester film, a cycloolefin derivative film, a polymethyl methacrylate film, a triacetyl cellulose, or an isobutyl ester cellulose film is preferable.

The thickness of the transparent base material 31 is preferably 5 μm to 200 μm, more preferably 20 μm to 100 μm.

The hard coat layer 32 has a function of improving the surface hardness of the transparent base material 31. Further, the hard coat layer 32 has light transmittance and flexibility.

The hard coat layer 32 can be formed by curing a hard coat composition containing a photocurable (meth)acrylate monomer or oligomer, a photocurable epoxy monomer or oligomer, or the like as a forming material.

In addition to the above-mentioned monomers and oligomers, the hard coat composition contains a solvent and a photoinitiator as necessary. In addition, the hard coat composition may contain additives such as inorganic fillers, leveling agents, stabilizers, antioxidants, UV absorbers, surfactants, lubricants, and antifouling agents to the extent that they do not impair the effects of the invention. May include.

The hard coat layer 32 can be formed by applying the above-described hard coat composition to at least one surface of the transparent base material 31 and curing it.

The thickness of the hard coat layer 32 is not particularly limited, but is preferably 5 μm to 100 μm. When the thickness of the hard coat layer 32 is 5 μm or more, sufficient impact resistance can be ensured. Further, when the thickness of the hard coat layer 32 is 100 μm or less, the hard coat layer 32 has sufficient flexibility for practical use. Further, when forming the hard coat layer 32, curling due to curing shrinkage of the hard coat composition is less likely to occur.

(touch sensor)
The optical display device 100 shown in FIG. 3 includes a touch sensor 40 between the display surface of the optical display panel 20 and the circularly polarizing plate 1. The touch sensor 40 includes a base material 41, a lower electrode 42 provided on the base material 41, an upper electrode 43 facing the lower electrode 42, and an insulating layer 44 sandwiched between the lower electrode 42 and the upper electrode 43. The touch sensor 40 shown in FIG. 3 is a so-called projected capacitive touch sensor.

The touch sensor 40 shown in FIG. 3 has a base material 41 facing the optical display panel 20 and an upper electrode 43 facing the circularly polarizing plate 30 with a front plate, and the circularly polarizing plate 30 with a front plate and the optical display panel 20. is sandwiched between.

As the base material 41, various materials can be used as long as it is a flexible resin film having light transmittance. For example, as the base material 41, the film exemplified as the material for the transparent base material 31 described above can be used.

The lower electrode 42 includes, for example, a plurality of small square electrodes in a plan view. The plurality of small electrodes 42a are arranged in a matrix.

Further, the plurality of small electrodes 42a are connected to each other by adjacent small electrodes 42a in one diagonal direction of the small electrodes 42a, forming a plurality of electrode rows. The plurality of electrode rows are connected to each other at their ends, making it possible to detect the capacitance between adjacent electrode rows.

The upper electrode 43 includes, for example, a plurality of small square electrodes in a plan view. The plurality of small electrodes 43a are complementary arranged in a matrix at positions where the lower electrode 42 is not arranged in plan view. That is, the upper electrode 43 and the lower electrode 42 are arranged without any gap in plan view.

Further, the plurality of small electrodes 43a are connected to each other by the small electrodes 43a adjacent to each other in the diagonal direction of the other small electrode 43a, thereby forming a plurality of electrode rows. The plurality of electrode rows are connected to each other at their ends, making it possible to detect the capacitance between adjacent electrode rows.

The insulating layer 44 insulates the lower electrode 42 and the upper electrode 43. As the material for forming the insulating layer 44, materials commonly known as materials for insulating layers of touch panels can be used.

In this embodiment, the touch sensor 40 has been described as being a so-called projected capacitive type touch sensor, but other types of touch sensors such as a membrane resistance type may be used as long as the effects of the invention are not impaired. Sensors can also be employed.

Each layer (front plate, circularly polarizing plate, touch sensor) forming the optical display device can be laminated using an adhesive. Adhesives include water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent volatilization adhesives, moisture-curing adhesives, heat-curing adhesives, anaerobic-curing adhesives, and active energy ray-curing adhesives. Commonly used adhesives, such as adhesives, curing agent mixed adhesives, hot-melt adhesives, pressure-sensitive adhesives (pressure-sensitive adhesives), and rewetting adhesives can be used. Among these, water-based solvent volatilization adhesives, active energy ray-curable adhesives, and adhesives are often used. The thickness of the adhesive layer can be adjusted as appropriate depending on the required adhesive strength, etc., and is 0.01 μm to 500 μm, preferably 0.1 μm to 300 μm. Although there are a plurality of laminates for a flexible image display device, the thickness types of the laminates may be the same or different.

As the water-based solvent volatilization type adhesive, a water-dispersed polymer such as a polyvinyl alcohol polymer, a water-soluble polymer such as starch, an ethylene-vinyl acetate emulsion, a styrene-butadiene emulsion, etc. can be used as the main polymer. In addition to water and the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, etc. may be added.

In the case of bonding with the aqueous solvent volatile adhesive, adhesiveness can be imparted by injecting the aqueous solvent volatile adhesive between the adherend layers, bonding the adherend layers, and then drying. When using the aqueous solvent volatile adhesive, the thickness of the adhesive layer may be 0.01 to 10 μm, preferably 0.1 μm to 1 μm. When using a plurality of layers of the water-based solvent volatilization type adhesive, the thickness types of the respective layers may be the same or different.

The active energy ray-curable adhesive includes a reactive material that forms an adhesive layer by irradiating active energy rays. When using the active energy ray curable adhesive, the adhesive layer can be formed by curing the active energy ray curable composition. The active energy ray-curable composition may contain at least one polymer of the same radical polymerizable compound and cationic polymerizable compound as the hard coat composition. The radically polymerizable compound is the same as the hard coat composition, and the same type of compound as the hard coat composition can be used. The radically polymerizable compound used in the adhesive layer is preferably a compound having an acryloyl group. In order to lower the viscosity of the adhesive composition, the active energy ray-curable adhesive preferably contains a monofunctional compound.

The cationic polymerizable compound is the same as that in the hard coat composition, and the same type of compound as in the hard coat composition can be used. As the cationically polymerizable compound used in the active energy ray-curable composition, epoxy compounds are particularly preferred. In order to lower the viscosity of the adhesive composition, it is also preferable that the cationically polymerizable compound contains a monofunctional compound as a reactive diluent.

The active energy ray-curable composition can further contain a polymerization initiator. Examples of the polymerization initiator include radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, and can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations to advance radical polymerization and cationic polymerization. As the polymerization initiator, the initiator used in the active energy ray-curable adhesive shown in the description of the light absorption layer above can be used.

The active energy ray-curable composition further contains an ion scavenger, an antioxidant, a chain transfer agent, an adhesion promoter, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, an antifoaming agent, an additive, and a solvent. can include. In the case of bonding with the active energy ray-curable adhesive, the active energy ray-curable composition is applied to one or both of the adhesive layers and then laminated, and the active energy ray-curable composition is pasted through either or both of the adhesive layers. Adhesion can be achieved by curing by irradiating active energy rays.

When using the active energy ray-curable adhesive, the thickness of the adhesive layer may be 0.01 μm to 20 μm, preferably 0.1 μm to 10 μm. When using a plurality of layers of the active energy ray-curable adhesive, the thicknesses of the respective layers may be the same or different.

As the pressure-sensitive adhesive (adhesive), any one classified into acrylic adhesives, urethane adhesives, rubber adhesives, silicone adhesives, etc. can be used depending on the main polymer. In addition to the base polymer, the adhesive may contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like. A pressure-sensitive adhesive composition is obtained by dissolving and dispersing each component constituting the pressure-sensitive adhesive in a solvent, and the pressure-sensitive adhesive composition is applied onto a base material and then dried to form an adhesive layer (adhesive layer). is formed. The adhesive layer may be formed directly or may be formed separately on a base material and transferred. It is also preferable to use a release film to cover the adhesive surface before adhesion.

When using the pressure-sensitive adhesive (adhesive), the thickness of the adhesive layer (adhesive layer) may be 0.1 μm to 500 μm, preferably 1 μm to 300 μm. When using multiple layers of the adhesive, the thickness of each layer may be the same or different.

Even with the optical display device 100 having the above configuration, coloring of reflected light can be suppressed and good image display can be performed.

Although preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. The various shapes and combinations of the constituent members shown in the above example are merely examples, and can be variously changed based on design requirements and the like without departing from the gist of the present invention.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
(Preparation of polarizer)
A polyvinyl alcohol film with a thickness of 30 μm (average degree of polymerization of approximately 2400, degree of saponification of 99.9 mol% or more) was uniaxially stretched approximately 5 times by dry stretching, and then immersed in pure water at 60°C while maintaining the tension state. After being immersed for 1 minute, it was immersed for 60 seconds in an aqueous solution at 28°C with a mass ratio of iodine/potassium iodide/water of 0.05/5/100.

Next, it was immersed for 300 seconds in a 72° C. aqueous solution having a mass ratio of potassium iodide/boric acid/water of 8.5/8.5/100.
Then, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizer with a thickness of 12 μm.
In the produced polarizer, iodine was adsorbed and oriented on the polyvinyl alcohol film.

(Preparation of water-based adhesive)
3 parts by mass of carboxy group-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name "KL-318") is dissolved in 100 parts of water, and a polyamide epoxy additive (water-soluble epoxy resin) is added to the resulting aqueous solution ( A water-based adhesive was prepared by adding 1.5 parts by mass of 1.5 parts by mass of ``Sumirezu Resin 650 (30)'' manufactured by Taoka Chemical Industry Co., Ltd., an aqueous solution with a solid content concentration of 30%).

(Preparation of polarizing plate)
The above-mentioned water-based adhesive was applied to one side of the obtained polarizer, and a norbornene-based resin film with a hard coat layer (manufactured by Nippon Paper Industries Co., Ltd., trade name "COP25ST-HC", hereinafter referred to as HC-COP) was laminated. did.
The HC-COP used was a film in which a hard coat resin with a thickness of 3 μm was formed on a stretched film made of a cycloolefin resin with a thickness of 25 μm.

The other side of the polarizer was coated with the water-based adhesive described above, and a 20 μm thick triacetyl cellulose resin film (manufactured by Fuji Film Corporation, product name "ZRG20SL", hereinafter referred to as TAC) was laminated. A polarizing plate was produced.

The corrected transmittance of the obtained polarizing plate was 45%.

(Preparation of retardation layer)
(Preparation of reverse wavelength dispersion liquid crystal)
Mixing 5 parts by mass of a photo-alignable material represented by the following formula (11) (mass average molecular weight: 30,000) and 95 parts by mass of cyclopentanone as a solvent, and stirring the resulting mixture at 80 ° C. for 1 hour. Thus, a composition for forming an alignment film was obtained.

Further, a mixture was prepared in which a polymerizable liquid crystal compound A represented by the following formula (12) and a polymerizable liquid crystal compound B represented by the following formula (13) were mixed at a mass ratio of 90:10.
Polymerizable liquid crystal compound A was produced by the method described in JP-A-2010-31223. Furthermore, polymerizable liquid crystal compound B was produced according to the method described in JP-A No. 2009-173893.

[Polymerizable liquid crystal compound A]

[Polymerizable liquid crystal compound B]

1.0 parts by mass of a leveling agent (manufactured by DIC Corporation, trade name "F-556") and a polymerization initiator, 2-dimethylamino-2-benzyl-1-(4-morpholino), were added to the resulting mixture. 6 parts by mass of phenyl)butan-1-one (manufactured by BASF Japan Co., Ltd., trade name "Irgacure (registered trademark) 369 (Irg369)") was added.
Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 13% by mass, and the mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a liquid crystal cured film.

As a base material, a 50 μm thick cycloolefin film (manufactured by Nippon Zeon Co., Ltd., trade name "ZF-14-50") was prepared.
After performing corona treatment on the base material, the composition for forming an alignment film was applied to the corona-treated surface using a bar coater, dried at 80°C for 1 minute, and heated using a polarized UV irradiation device (manufactured by Ushio Inc., product An alignment film was formed by polarized UV exposure at an axis angle of 45° and an integrated light amount of 100 mJ/cm ² at a wavelength of 313 nm.

Subsequently, a composition for forming a liquid crystal cured film was applied to the alignment film using a bar coater, and dried at 120° C. for 1 minute.
Thereafter, the coating film of the composition for forming a liquid crystal cured film was irradiated with ultraviolet rays using a high-pressure mercury lamp (manufactured by Ushio Inc., trade name: "Unicure VB-15201BY-A"). The ultraviolet irradiation conditions were under a nitrogen atmosphere with an integrated light amount of 500 mJ/cm ² at a wavelength of 365 nm.
Thereby, a cured liquid crystal film was formed, and a laminate in which the base material, the alignment film, and the cured liquid crystal film were laminated was obtained. The laminate of the alignment film and the cured liquid crystal film corresponds to the "retardation layer" in the present invention.

The laminate produced by the above method was bonded to glass via an adhesive layer. The surface in contact with the adhesive layer was made to be a cured liquid crystal film. The cycloolefin film as a base material was peeled off from the laminate to obtain a sample for retardation value measurement.

The in-plane retardation value Re (λ) of the obtained retardation layer was measured using a measuring device (manufactured by Oji Scientific Instruments Co., Ltd., trade name "KOBRA-WPR").

The measurement results of the retardation value Re (λ) at each wavelength were Re (450) = 121 nm, Re (550) = 142 nm, and Re (650) = 146 nm. Re(450)/Re(550)=0.85 and Re(650)/Re(550)=1.03.

FIG. 2 is a graph showing the ratio of the phase difference of light of other wavelengths to the phase difference of light of wavelength 550 nm in the obtained retardation layer. In FIG. 2, the horizontal axis shows the wavelength (unit: nm), and the vertical axis shows the ratio (unit: dimensionless) of the phase difference of light with other wavelengths to the phase difference of light with a wavelength of 550 nm. In the figure, the line indicated by the symbol S1 is a line indicating the phase difference of the retardation layer in an ideal state, which converts light of any wavelength into ideal circularly polarized light. Such a line is called an "ideal curve."

(Preparation of adhesive composition containing dye)
(Preparation of acrylic resin)
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer, 81.8 parts by mass of ethyl acetate as a solvent, 70.4 parts by mass of butyl acrylate as monomers, 20.0 parts by mass of methyl acrylate, A mixed solution of 8.0 parts by mass of 2-phenoxyethyl acrylate, 1.0 parts by mass of 2-hydroxyethyl acrylate, and 0.6 parts by mass of acrylic acid was charged.

The inside of the reaction vessel was replaced with a nitrogen atmosphere, and the internal temperature of the reaction vessel was raised to 55°C. Separately, prepare a solution of 0.14 parts by mass of azobisisobutyronitrile, a polymerization initiator, dissolved in 10 parts by mass of ethyl acetate, and place the polymerization initiator solution in a reaction vessel whose internal temperature is 55°C. The whole amount was added. The temperature was maintained for 1 hour after the addition of the initiator.

Next, while maintaining the internal temperature at 54 to 56°C, ethyl acetate was continuously added into the reaction vessel at an addition rate of 17.3 parts by mass/hr. Addition of ethyl acetate was stopped when the concentration of the resulting polymer reached 35% by mass.

After keeping the temperature at 54 to 56°C until 12 hours had elapsed from the start of addition of ethyl acetate, ethyl acetate was added to adjust the polymer concentration to 20% by mass to obtain the desired acrylic resin.

(Synthesis of pigment)
A 100 mL four-necked flask equipped with a Dimroth condenser and a thermometer was set in a nitrogen atmosphere, and a compound represented by the following formula (14) (hereinafter referred to as compound (14) ) was synthesized.

2.0 g of powder of the obtained compound (14), 1.2 g of triethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 20 mg of N,N-dimethyl-4-aminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.), 8 g of chloroform was charged into a reaction vessel, stirred with a magnetic stirrer, and cooled to an internal temperature of 0°C in an ice bath.

A solution was prepared by dissolving 1.4 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) in 2.0 g of chloroform. The prepared solution was dropped over 2 hours using a dropping funnel into the reaction vessel whose internal temperature was maintained at 0°C. After the dropwise addition was completed, the mixture was kept at 0° C. for an additional 6 hours.

After the reaction was completed, chloroform was removed using an evaporator. The obtained oil was dissolved in ethyl acetate and washed with 10% dilute sulfuric acid, and then the ethyl acetate solution was washed with pure water until the pH of the aqueous layer became >6.

After drying the washed organic layer with Glauber's salt and removing the Glauber's salt, ethyl acetate was removed using an evaporator to obtain a dye represented by the following formula (15) (hereinafter referred to as compound (15)).

(Preparation of adhesive composition containing dye)
For 100 parts by mass of the solid content of the synthesized acrylic resin, 0.5 parts by mass of a crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate"), 0.5 parts by mass of 3-glycidoxypropyltrimethoxysilane ( (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403"), 3.5 parts by mass of compound (15) was blended. Furthermore, 2-butanone was added so that the solid content concentration was 14% by mass.

The obtained composition was stirred and mixed for 30 minutes at 300 rpm using a stirrer (manufactured by Yamato Scientific Co., Ltd., trade name "Three-One Motor") to prepare an adhesive composition containing a dye (compound (15)). .

(Preparation of adhesive sheet containing pigment)
The above-mentioned adhesive was applied to the release-treated surface of a polyethylene terephthalate film (manufactured by Lintec Corporation, product name "SP-PLR382050") that had been subjected to a release treatment, so that the thickness of the adhesive layer after drying was 20 μm. It was applied using an applicator. It was dried at 100° C. for 1 minute to prepare a dye-containing adhesive sheet.

One side of the resulting adhesive sheet was laminated to alkali-free glass (manufactured by Corning, trade name: Eagle Company's product name "ZF-14-23") was laminated. Next, the transmittance of the obtained laminate at 390 nm, 410 nm, and 430 nm was measured using a spectrophotometer with an integrating sphere ("V7100" manufactured by JASCO Corporation).

The transmittance of the obtained laminate, excluding the influence of interface reflection, was as follows.
Tb(390)≦0.001%
Tb(410)≦0.8%
Tb(430)≦83.0%

(Preparation of circularly polarizing plate)
The above-mentioned adhesive sheet was laminated onto the triacetyl cellulose resin protective film of the polarizing plate.

Next, the polyethylene terephthalate film was peeled off from the adhesive sheet, and the liquid crystal cured film surface of the above-mentioned retardation layer was bonded to the exposed adhesive layer. The obtained adhesive layer corresponds to the "light absorption layer" in the present invention.

Next, after peeling off the cycloolefin film laminated with the retardation layer, a 25 μm thick acrylic adhesive (manufactured by Lintec Corporation, trade name "P-3132") is laminated on the exposed surface, and circularly polarized light is Got the board.

The circularly polarizing plate had a layer structure of HC-COP, polarizer, TAC, adhesive layer (light absorption layer), liquid crystal cured film, alignment film, and adhesive layer.

[Measurement of transmittance]
The circularly polarizing plate was bonded to alkali-free glass (manufactured by Corning, trade name "Eagle XG") via an adhesive layer. Transmittance at 390 nm, 410 nm, and 430 nm was measured using an ultraviolet-visible near-infrared spectrophotometer (manufactured by JASCO Corporation, trade name "V-7100").

The transmittance was measured in the absorption axis direction and the transmission axis direction of the polarizer, and the transmittance at each wavelength λ nm was determined from the following formula (A).
T(λ) = ((Transmittance in the absorption axis direction) + (Transmittance in the transmission axis direction))/2...(A)

The transmittance Ta(λ) of the produced circularly polarizing plate was Ta(390)=0.12%, Ta(410)=4.53%, and Ta(430)=39.40%.

[Measurement of reflected hue]
The circularly polarizing plate was bonded to the display surface of an OLED display element (manufactured by Samsung Electronics Co., Ltd., trade name "Galaxy-Tab S8.4") via an adhesive layer. Reflection hue b* was measured using a spectrophotometer (manufactured by Konica Minolta, Inc., trade name "CM-2600d") in a non-lit state.

[Visual evaluation of appearance]
The appearance of the sample prepared by measuring the reflected hue was visually observed. The evaluation criteria are as follows. Samples evaluated as "◎" and "○" were determined to be good products, and samples evaluated as "×" were determined to be defective products.
(Evaluation criteria)
◎: Black ○: Black with a slight bluish tinge ×: Blue

(Example 2)
A circularly polarizing plate was produced in the same manner as in Example 1, except that the amount of compound (15) added was 2.5 parts by mass when producing the adhesive composition. The transmittance of the adhesive layer measured in the same manner as in Example 1 was as follows.
Tb(390)≦0.001%
Tb(410)≦3.2%
Tb(430)≦86.9%

(Example 3)
A circularly polarizing plate was produced in the same manner as in Example 1, except that the amount of compound (15) added was 1.0 parts by mass when producing the adhesive composition. The transmittance of the adhesive layer measured in the same manner as in Example 1 was as follows.
Tb(390)≦0.01%
Tb(410)≦3.2%
Tb(430)≦95.0%

(Example 4)
A circularly polarizing plate was produced in the same manner as in Example 1, except that the amount of compound (15) added was 0.02 parts by mass when producing the adhesive composition. The transmittance of the adhesive layer measured in the same manner as in Example 1 was as follows.
Tb(390)≦81.9%
Tb(410)≦97.2%
Tb(430)≦99.0%

(Example 5)
A circularly polarizing plate was produced in the same manner as in Example 1, except that the amount of compound (15) added was 0.035 parts by mass when producing the adhesive composition. The transmittance of the adhesive layer measured in the same manner as in Example 1 was as follows.
Tb(390)≦70.5%
Tb(410)≦95.2%
Tb(430)≦98.0%

(Comparative example 1)
A circularly polarizing plate was produced in the same manner as in Example 1, except that the light-selective absorptive adhesive sheet was changed to a 5 μm thick acrylic adhesive (manufactured by Lintec Corporation, trade name "#L2"). The acrylic pressure-sensitive adhesive used did not contain a dye (compound (15)).

One side of the used 5 μm thick acrylic adhesive (manufactured by Lintec Corporation, trade name "#L2") was laminated to an alkali-free glass (manufactured by Corning Corporation, trade name "Eagle XG") adhesive, and A 23 μm thick cycloolefin film (manufactured by Nippon Zeon Co., Ltd., trade name "ZF-14-23") was laminated on the other side of the acrylic adhesive. The transmittance of the obtained laminate at 390 nm, 410 nm, and 430 nm was measured using a spectrophotometer with an integrating sphere in the same manner as in Examples. The transmittance of the acrylic adhesive was as follows.
Tb(390)≦99.9%
Tb(410)≦99.9%
Tb(430)≦99.9%

The evaluation results are shown in Table 1.

As a result of the evaluation, it was found that each of the circularly polarizing plates of Examples 1 to 5 had a reflection hue b* closer to 0 and had a reduced bluish tinge compared to the circularly polarizing plate of Comparative Example 1.

From the above, it was found that the present invention is useful.

2... Polarizer layer, 3... Retardation layer, 7... Light absorption layer, 8... Adhesive layer, 10... Optical display device, 20... Optical display panel

Claims (6)

a polarizer layer;
a retardation layer;
A circularly polarizing plate comprising a light absorption layer,
The retardation layer satisfies the following formulas (1) and (2), where Re (λ) is the in-plane retardation value for light with a wavelength of λ nm, and Re (550) = 142 nm,
The light absorption layer has a base layer and a dye dispersed in the base layer,
The dye has a maximum absorption wavelength in a wavelength band of 390 to 430 nm,
A circularly polarizing plate in which a transmittance Ta (λ) of the circularly polarizing plate for light having a wavelength of λnm satisfies the following formulas (I) to (III).
0.80<Re(450)/Re(550)<0.90...(1)
1.00<Re(650)/Re(550)<1.30...(2)
Ta(390)≦0.22%…(I)
Ta(410)≦4.92%…(II)
Ta(430)≦40.08%…(III) The circularly polarizing plate according to claim 1 , wherein the base material layer is a pressure-sensitive adhesive layer or an adhesive layer. The circularly polarizing plate according to claim 1 or 2 , wherein a transmittance Tb (λ) of the light absorption layer for light having a wavelength of λ nm satisfies the following formulas (i) to (iii).
Tb(390)≦85%…(i)
Tb(410)≦98%…(ii)
Tb(430)≦99%…(iii) an optical display panel;
An optical display device comprising: the circularly polarizing plate according to any one of claims 1 to 3 bonded to a display surface of the optical display panel. The circularly polarizing plate is arranged such that the polarizer layer is on the opposite side of the optical display panel with respect to the retardation layer,
The optical display device according to claim 4 , further comprising a front plate on the polarizer layer side of the circularly polarizing plate. The optical display device according to claim 5 , further comprising a touch sensor between the display surface and the circularly polarizing plate.

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