WO2021024544A1

WO2021024544A1 - Retardation-layer-equipped polarizing plate, and image display device using same

Info

Publication number: WO2021024544A1
Application number: PCT/JP2020/012254
Authority: WO
Inventors: 圭太小川; 理小島
Original assignee: 日東電工株式会社
Priority date: 2019-08-02
Filing date: 2020-03-19
Publication date: 2021-02-11
Also published as: CN114207484A; KR20220038342A; TW202107128A; JP2021026086A

Abstract

Provided is a retardation-layer-equipped polarizing plate that is thin and in which warping can be inhibited when the plate is applied to an image display device. The retardation-layer-equipped polarizing plate according to the present invention comprises: a polarizing plate that includes a polarizer and a protective layer that is on at least the visible side of the polarizer; a first retardation layer bonded by a first adhesive layer to the side, of the polarizing plate, opposite the visible side; a second retardation layer bonded by a second adhesive layer to the first retardation layer; and an adhesive agent layer provided on the side, of the second retardation layer, opposite from the first retardation layer. The visible-side protective layer has a humidification linear expansion coefficient, in the direction of the absorption axis of the polarizer, of 6×10–5/% RH or less, and the distance from the center point of the total thickness to the visible-side surface of the visible-side protective layer is 45 μm or less.

Description

Polarizing plate with retardation layer and image display device using it

The present invention relates to a polarizing plate with a retardation layer and an image display device using the same.

In recent years, image display devices represented by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) have rapidly become widespread. A polarizing plate and a retardation plate are typically used in the image display device. Practically, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (for example, Patent Document 1), and recently, there is a strong demand for a thinner image display device. As a result, there is an increasing demand for thinner polarizing plates with retardation layers. Further, in recent years, there has been an increasing demand for a curved image display device and / or a bendable or bendable image display device. When a thin polarizing plate with a retardation layer is applied to such an image display device, there is a problem that warpage occurs.

Japanese Patent No. 3325560

The present invention has been made to solve the above-mentioned conventional problems, and a main object thereof is to provide a polarizing plate with a retardation layer which is thin and can suppress warpage when applied to an image display device. There is.

The polarizing plate with a retardation layer of the present invention is provided via a polarizing plate, a polarizing plate including a protective layer at least on the visible side of the polarizing element, and a first adhesive layer on the side opposite to the visible side of the polarizing plate. The first retardation layer bonded to the first retardation layer, the second retardation layer bonded to the first retardation layer via the second adhesive layer, and the second retardation layer. It has a pressure-sensitive adhesive layer provided on the opposite side of the first retardation layer. The coefficient of linear expansion of the humidifying line in the absorption axis direction of the polarizing element of the protective layer on the visible side is 6 × 10 ^-5 /% RH or less, from the midpoint of the total thickness to the visible surface of the protective layer on the visible side. The distance is 45 μm or less.
In one embodiment, the first retardation layer and the second retardation layer are each an orientation-solidified layer of a liquid crystal compound.
In one embodiment, the polarizing plate with a retardation layer has a total thickness of 100 μm or less.
In one embodiment, the Re (550) of the first retardation layer is 200 nm to 300 nm, and the angle between its slow axis and the absorber absorption axis is 10 ° to 20 °; The Re (550) of the second retardation layer is 100 nm to 190 nm, and the angle formed by the slow axis thereof and the absorption axis of the polarizer is 70 ° to 80 °.
In one embodiment, the polarizing plate with a retardation layer is attached to a polyimide film via the pressure-sensitive adhesive layer, and is left to stand for 24 hours under the conditions of 20 ° C. and 98% RH. Is 30 mm or less.
According to another aspect of the present invention, an image display device is provided. This image display device includes the above-mentioned polarizing plate with a retardation layer.
In one embodiment, the image display device is an organic electroluminescence display device.

According to the present invention, in a thin polarizing plate with a retardation layer, the coefficient of linear expansion of the humidifying line in the direction of the polarizer absorption axis of the viewing side protective layer and the distance from the midpoint of the total thickness to the viewing side surface of the viewing side protective layer. By optimizing, it is possible to realize a polarizing plate with a retardation layer that can suppress warpage when applied to an image display device.

It is schematic cross-sectional view of the polarizing plate with a retardation layer by one Embodiment of this invention.

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

(Definition of terms and symbols)
Definitions of terms and symbols 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 maximized (that is, the slow-phase axis direction), and "ny" is the in-plane direction orthogonal to the slow-phase axis (that is, the phase-advance axis direction). Is the refractive index of, and "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
“Re (λ)” is an in-plane phase difference measured with light having a wavelength of λ nm at 23 ° C. For example, "Re (550)" is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained by the formula: Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in the thickness direction (Rth)
“Rth (λ)” is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (550)" is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is obtained by the formula: Rth (λ) = (nx−nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.
(5) Angle When referring to an angle herein, the angle includes both clockwise and counterclockwise with respect to the reference direction. Therefore, for example, "45 °" means ± 45 °.

A. Overall Configuration of Polarizing Plate with Difference Layer FIG. 1 is a schematic cross-sectional view of the polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a retardation layer in the illustrated example typically has a polarizing plate 10, a first retardation layer 21, and a second retardation layer 22 in this order from the viewing side. The polarizing plate 10 includes a polarizing element 11 and a protective layer 12 at least on the visible side of the polarizing element 11. In the illustrated example, the protective layer 13 is provided on the side opposite to the visible side of the polarizer 11, but the protective layer 13 may be omitted depending on the purpose or the like. The first retardation layer 21 is bonded to the side opposite to the visible side of the polarizing plate 10 via the first adhesive layer 31. The second retardation layer 22 is bonded to the side opposite to the visible side of the first retardation layer 21 via the second adhesive layer 32. Practically, the pressure-sensitive adhesive layer 40 is provided on the side of the second retardation layer 22 opposite to the first retardation layer 21 (that is, as the outermost layer on the side opposite to the viewing side), and polarized light with a retardation layer is provided. The board can be attached to the image display cell. Further, it is preferable that a release film (not shown) is temporarily attached to the surface of the pressure-sensitive adhesive layer 40 until the polarizing plate with a retardation layer is used. By temporarily attaching the release film, the pressure-sensitive adhesive layer can be protected and a roll of the polarizing plate with a retardation layer can be formed.

The first retardation layer 21 and the second retardation layer 22 are typically oriented solidification layers of liquid crystal compounds, respectively. By using the liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be remarkably increased as compared with the non-liquid crystal material, so that the thickness of the retardation layer for obtaining a desired in-plane retardation can be obtained. Can be made much smaller. As a result, it is possible to realize a remarkable reduction in thickness of the polarizing plate with a retardation layer. As used herein, the term "oriented solidified layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and the oriented state is fixed. The "oriented solidified layer" is a concept including an oriented cured layer obtained by curing a liquid crystal monomer as described later. In the first retardation layer 21 and the second retardation layer 22, typically, rod-shaped liquid crystal compounds are arranged in the slow axis direction of the first retardation layer or the second retardation layer. Oriented in (homogeneous orientation). Typically, either one of the first retardation layer 21 or the second retardation layer 22 can function as a λ / 2 plate and the other can function as a λ / 4 plate. For example, when the first retardation layer 21 can function as a λ / 2 plate and the second retardation layer 22 can function as a λ / 4 plate, the Re (550) of the first retardation layer 21 ) Is preferably 200 nm to 300 nm, and the angle formed by the slow axis thereof and the absorption axis of the polarizer 10 is preferably 10 ° to 20 °; Re (550) of the second retardation layer 22 is preferable. Is 100 nm to 190 nm, and the angle formed by the slow axis thereof and the absorption axis of the polarizer 10 is preferably 70 ° to 80 °.

In the embodiment of the present invention, the humidification line expansion coefficient of the polarizing element 11 of the protective layer 12 in the absorption axis direction is 6 × ^10-5 /% RH or less, preferably 5 × ^10-5 /% RH or less. , More preferably 4 × 10 ^-5 /% RH or less, further preferably 2 × 10 ^-5 /% RH or less, and particularly preferably 1 × 10 ^-5 /% RH or less. The lower limit of the humidification line expansion coefficient can be, for example, 0.3 × ^10-5 /% RH. If the coefficient of expansion of the humidified line is within such a range, the distance from the midpoint of the total thickness of the polarizing plate with a retardation layer to the outermost surface on the visual side is optimized (described later) due to a synergistic effect. When a polarizing plate with a retardation layer is applied to an image display device, warpage can be remarkably suppressed. In the present specification, the "humidified linear expansion coefficient" means the linear expansion coefficient when the relative humidity is changed from 10% to 90% at a temperature of 25 ° C. The coefficient of linear expansion can be measured, for example, by thermomechanical analysis (TMA).

Further, in the embodiment of the present invention, the viewing side surface of the protective layer on the viewing side from the midpoint of the total thickness of the polarizing plate with the retardation layer (substantially, the outermost surface on the viewing side of the polarizing plate with the retardation layer). The distance L to the distance L is 45 μm or less, preferably 42 μm or less, more preferably 35 μm or less, and further preferably 30 μm or less. The lower limit of the distance L can be, for example, 20 μm. When the distance L is in such a range, the warp is remarkably suppressed when the polarizing plate with a retardation layer is applied to the image display device due to the synergistic effect with the effect of optimizing the humidification line expansion coefficient. can do. More details are as follows. By setting the distance L to the above-mentioned predetermined value or less, the moment of force of the polarizing plate with a retardation layer can be reduced, and as a result, warpage can be suppressed. Since the moment of force can correlate with the distance from the center to the outermost surface, optimizing the distance L corresponding to the distance has technical significance. Further, by setting the coefficient of linear expansion of the humidifying line of the visible side protective layer to a predetermined value or less, the moment of force of the portion from the center to the outermost surface can be further reduced, and a synergistic effect can be realized. In the present specification, the "total thickness of the polarizing plate with the retardation layer" means the thickness from the visual side protective layer to the pressure-sensitive adhesive layer.

The total thickness of the polarizing plate with a retardation layer is preferably 100 μm or less, more preferably 85 μm or less, further preferably 60 μm or less, and particularly preferably 55 μm or less. The lower limit of the total thickness can be, for example, 28 μm. A polarizing plate with a retardation layer having such a total thickness can have extremely excellent flexibility and bending durability. As a result, the polarizing plate with a retardation layer can be particularly preferably applied to a curved image display device and / or a bendable or bendable image display device.

In one embodiment, the polarizing plate with a retardation layer is attached to a polyimide film via an adhesive layer 40 and left to stand for 24 hours (humidification test) at 20 ° C. and 98% RH. The absolute value of is preferably 30 mm or less, more preferably 25 mm or less, still more preferably 20 mm or less, and particularly preferably 15 mm or less. The smaller the absolute value of the amount of warpage, the more preferable, and the lower limit thereof can be, for example, 2 mm. The thickness of the polyimide film is, for example, 30 μm to 100 μm, preferably 40 μm to 80 μm. Such a polarizing plate with a retardation layer can remarkably suppress warpage when applied to a curved image display device and / or a bendable or bendable image display device. The amount of warpage is expressed by the following formula.
Warp amount = (warp amount 1-warp amount 2)
Here, the "warp amount 1" is the warp amount of the laminated body of the polarizing plate with the retardation layer and the polyimide film before the humidification test, and the "warp amount 2" is the warp amount of the laminated body after the humidification test. In the present specification, the case where the warp is convex toward the image display cell side is represented by "positive (+)", and the case where the warp is convex toward the visual recognition side is represented by "negative (-)".

The polarizing plate with a retardation layer may further include other optical functional layers. The type, characteristics, number, combination, arrangement position, and the like of the optical functional layers that can be provided on the polarizing plate with the retardation layer can be appropriately set according to the purpose. For example, the polarizing plate with a retardation layer may further have a conductive layer or an isotropic base material with a conductive layer (neither is shown). The conductive layer or the isotropic base material with the conductive layer is typically provided on the outside (opposite side of the polarizing plate 10) of the second retardation layer 22. The conductive layer or the isotropic base material with the conductive layer is typically an arbitrary layer provided as needed, and may be omitted. When an isotropic base material with a conductive layer or a conductive layer is provided, the polarizing plate with a retardation layer is a so-called inner in which a touch sensor is incorporated between an image display cell (for example, an organic EL cell) and the polarizing plate. It can be applied to a touch panel type input display device. Further, for example, the polarizing plate with a retardation layer may further include other retardation layers. The optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of the other retardation layers can be appropriately set according to the purpose.

The above-described embodiments may be combined as appropriate, the components in the above-described embodiments may be modified in the art, and the configurations in the above-described embodiments may be replaced with optically equivalent configurations.

The polarizing plate with a retardation layer of the present invention may be single-wafered or elongated. As used herein, the term "long" means an elongated shape having a length sufficiently long with respect to the width, and for example, an elongated shape having a length of 10 times or more, preferably 20 times or more with respect to the width. Including. The elongated polarizing plate with a retardation layer can be wound in a roll shape.

Hereinafter, the components of the polarizing plate with a retardation layer will be described in more detail.

B. Polarizing plate B-1. Polarizer As the polarizer 11, any suitable polarizer can be adopted. For example, the resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer system partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine or a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical characteristics, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is used.

The dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Moreover, you may dye after stretching. If necessary, the PVA-based film is subjected to a swelling treatment, a cross-linking treatment, a washing treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt on the surface of the PVA-based film and the blocking inhibitor, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizer obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further include, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. The obtained resin base material / polarizer laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizer), and the resin base material is peeled off from the resin base material / polarizer laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface. Details of the method for producing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire description of these publications is incorporated herein by reference.

The thickness of the polarizer is preferably 15 μm or less, more preferably 1 μm to 12 μm, further preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is 43.0% to 46.0%, preferably 44.5% to 46.0%, as described above. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

B-2. Protective Layer The protective layer 12 and the protective layer 13 (if any) are each formed of any suitable film that can be used as a protective layer for the polarizer. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based. , Polystyrene-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Further, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

The polarizing plate with a retardation layer of the present invention is typically arranged on the visible side of an image display device as described later, and the protective layer 12 is arranged on the visible side thereof. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coat treatment, antireflection treatment, anti-sticking treatment, and anti-glare treatment, if necessary. Further / or, if necessary, the protective layer 12 is provided with a process for improving visibility when visually recognizing through polarized sunglasses (typically, providing a (elliptical) circular polarization function, ultra-high phase difference). May be given). By performing such a process, excellent visibility can be realized even when the display screen is visually recognized through a polarized lens such as polarized sunglasses. Therefore, the polarizing plate with a retardation layer can be suitably applied to an image display device that can be used outdoors.

The thickness of the protective layer 12 is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 10 μm to 30 μm. When the surface treatment is applied, the thickness of the protective layer 12 is a thickness including the thickness of the surface treatment layer.

The protective layer 13 is preferably optically isotropic in one embodiment. In the present specification, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. Say. In another embodiment, the protective layer 13 can be a retardation layer having any suitable retardation value. In this case, the in-plane retardation Re (550) of the retardation layer is, for example, 110 nm to 150 nm. The thickness of the protective layer 13 is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 10 μm to 30 μm. From the viewpoint of thinning, the protective layer 13 may be preferably omitted.

C. First Phase Difference Layer and Second Phase Difference Layer As described above, the first phase difference layer 21 and the second phase difference layer 22 (hereinafter, may be collectively referred to as a phase difference layer) are liquid crystals, respectively. It is an orientation solidification layer of a compound (hereinafter, a liquid crystal orientation solidification layer). Examples of the liquid crystal compound include a liquid crystal compound (nematic liquid crystal) in which the liquid crystal phase is a nematic phase. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The liquid crystal expression mechanism of the liquid crystal compound may be either lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. This is because the orientation state of the liquid crystal monomer can be fixed by polymerizing or cross-linking (that is, curing) the liquid crystal monomer. After the liquid crystal monomers are oriented, for example, if the liquid crystal monomers are polymerized or crosslinked with each other, the oriented state can be fixed. Here, the polymer is formed by polymerization, and the three-dimensional network structure is formed by cross-linking, but these are non-liquid crystal. Therefore, the formed retardation layer does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change peculiar to a liquid crystal compound, for example. As a result, the retardation layer becomes an extremely stable retardation layer that is not affected by temperature changes.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity differs depending on the type. Specifically, the temperature range is preferably 40 ° C. to 120 ° C., more preferably 50 ° C. to 100 ° C., and most preferably 60 ° C. to 90 ° C.

Any suitable liquid crystal monomer can be adopted as the liquid crystal monomer. For example, the polymerizable mesogen compounds described in Special Tables 2002-533742 (WO00 / 37585), EP358208 (US521187), EP66137 (US4388453), WO93 / 22397, EP02671712, DE19504224, DE4408171, GB2280445 and the like can be used. Specific examples of such a polymerizable mesogen compound include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Sillicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

The liquid crystal alignment solidified layer is subjected to an orientation treatment on the surface of a predetermined base material, and a coating liquid containing a liquid crystal compound is applied to the surface to orient the liquid crystal compound in a direction corresponding to the orientation treatment. It can be formed by fixing the state. In one embodiment, the substrate is any suitable resin film, and the liquid crystal oriented solidified layer (first retardation layer 21) formed on the substrate comprises the first adhesive layer 31. It can be transferred to the surface of the polarizing plate 10 via. Similarly, the liquid crystal oriented solidifying layer (second retardation layer 22) formed on the substrate can be transferred to the surface of the first retardation layer 21 via the second adhesive layer 32.

As the orientation treatment, any appropriate orientation treatment can be adopted. Specific examples thereof include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of the mechanical orientation treatment include a rubbing treatment and a stretching treatment. Specific examples of the physical orientation treatment include magnetic field orientation treatment and electric field orientation treatment. Specific examples of the chemical alignment treatment include an orthorhombic deposition method and a photoalignment treatment. As the treatment conditions for various orientation treatments, any appropriate conditions may be adopted depending on the purpose.

The orientation of the liquid crystal compound is performed by treating at a temperature indicating the liquid crystal phase according to the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound takes a liquid crystal state, and the liquid crystal compound is oriented according to the orientation treatment direction of the substrate surface.

In one embodiment, the orientation state is fixed by cooling the liquid crystal compound oriented as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the orientation state is fixed by subjecting the liquid crystal compound oriented as described above to a polymerization treatment or a crosslinking treatment.

Specific examples of the liquid crystal compound and details of the method for forming the oriented solidified layer are described in JP-A-2006-163343. The description of this publication is incorporated herein by reference.

The retardation layer typically shows a relationship in which the refractive index characteristic is nx> ny = nz. It should be noted that "ny = nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny> nz or ny <nz may occur within a range that does not impair the effects of the present invention.

As described above, either one of the first retardation layer 21 or the second retardation layer 22 can function as a λ / 2 plate, and the other can function as a λ / 4 plate. Here, the case where the first retardation layer 21 can function as a λ / 2 plate and the second retardation layer 22 can function as a λ / 4 plate will be described, but these may be reversed. .. The thickness of the first retardation layer 21 can be adjusted to obtain the desired in-plane retardation of the λ / 2 plate, for example 2.0 μm to 4.0 μm. The thickness of the second retardation layer 22 can be adjusted to obtain the desired in-plane retardation of the λ / 4 plate, for example 1.0 μm to 2.5 μm. The in-plane retardation Re (550) of the first retardation layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and further preferably 250 nm to 280 nm as described above. The in-plane retardation Re (550) of the second retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and further preferably 130 nm to 160 nm as described above. The angle formed by the slow axis of the first retardation layer 21 and the absorption axis of the polarizer 10 is preferably 10 ° to 20 °, more preferably 12 ° to 18 °, and even more preferably, as described above. Is about 15 °. The angle formed by the slow axis of the second retardation layer 22 and the absorption axis of the polarizer 10 is preferably 70 ° to 80 °, more preferably 72 ° to 78 °, and even more preferably, as described above. Is about 75 °. With such a configuration, it is possible to obtain characteristics close to the ideal reverse wavelength dispersion characteristic, and as a result, it is possible to realize extremely excellent antireflection characteristics.

The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3. By satisfying such a relationship, a very excellent reflected hue can be achieved when the obtained polarizing plate with a retardation layer is used in an image display device.

The retardation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, or may exhibit a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It is also possible to exhibit a flat wavelength dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light.

D. Adhesive Layer The first adhesive layer 31 and the second adhesive layer 32 will be collectively described as an adhesive layer. The first adhesive layer and the second adhesive layer may have the same structure or may have different structures from each other. Any suitable adhesive may be adopted as the adhesive constituting the adhesive layer. A typical example of the adhesive is an active energy ray-curable adhesive. Examples of the active energy ray-curable adhesive include an ultraviolet curable adhesive and an electron beam-curable adhesive. From the viewpoint of the curing mechanism, examples of the active energy ray-curable adhesive include radical curing type, cationic curing type, anion curing type, and a hybrid of radical curing type and cationic curing type. Typically, a radical curable UV curable adhesive can be used. This is because it has excellent versatility and its characteristics (configuration) can be easily adjusted.

The adhesive typically contains a curing component and a photopolymerization initiator. Typical examples of the curing component include monomers and / or oligomers having a functional group such as a (meth) acrylate group and a (meth) acrylamide group. Specific examples of the curing component include tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecanedimethanol diacrylate, phenoxydiethylene glycol acrylate, cyclic trimethylolpropaneformal acrylate, dioxane glycol diacrylate, and EO modification. Diglycerin tetraacrylate, γ-butyrolactone acrylate, acryloylmorpholine, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone, N-methylpyrrolidone, hydroxyethylacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide Can be mentioned. These curing components may be used alone or in combination of two or more.

Preferably, the adhesive contains a curing component having a heterocycle. Examples of the curing component having a heterocycle include acryloyl morpholine, γ-butyrolactone acrylate, unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone, and N-methylpyrrolidone. More preferred curing components are unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone and acryloyl morpholine, and particularly preferred curing components are acryloyl morpholine. The cured component having a heterocycle is preferably 50 parts by weight or more, more preferably 60 parts by weight, based on 100 parts by weight of the cured component (the total of the cured component and the oligomer component when the oligomer component described later is present). As described above, more preferably, it can be contained in the adhesive in a proportion of 70 parts by weight to 95 parts by weight. Acryloylmorpholin is preferably 5 parts by weight to 60 parts by weight, more preferably 10 parts by weight to 50 parts by weight, based on 100 parts by weight of the curing component (the total of the curing component and the oligomer component when the oligomer component is present). It can be contained in the adhesive in proportions of parts.

The adhesive may further contain an oligomer component in addition to the above-mentioned curing component. By using the oligomer component, the viscosity of the adhesive before curing can be reduced and the operability can be improved. A typical example of the oligomer component is a (meth) acrylic oligomer. Examples of the (meth) acrylic monomer constituting the (meth) acrylic oligomer include (meth) acrylic acid (1 to 20 carbon atoms) alkyl esters, cycloalkyl (meth) acrylates (for example, cyclohexyl (meth) acrylates, etc. Cyclopentyl (meth) acrylate, etc.), Aralkyl (meth) acrylate (eg, benzyl (meth) acrylate, etc.), Polycyclic (meth) acrylate (eg, 2-isobornyl (meth) acrylate, 2-norbornylmethyl (meth) ) Acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, etc.), hydroxyl group-containing (meth) acrylic acid esters (eg, hydroxyethyl (eg, hydroxyethyl) (Meta) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethyl-butyl (meth) methacrylate, etc.), alkoxy group- or phenoxy group-containing (meth) acrylic acid esters (2-methoxyethyl (meth)) Acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), containing epoxy group (Meta) acrylic acid esters (eg, glycidyl (meth) acrylate, etc.), halogen-containing (meth) acrylic acid esters (eg, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,2- Trifluoroethyl ethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) Acrylate (eg, dimethylaminoethyl (meth) acrylate, etc.) can be mentioned. Specific examples of (meth) acrylic acid (1 to 20 carbon atoms) alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and 2-methyl. -2-Nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, t- Pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl Examples thereof include (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, and n-octadecyl (meth) acrylate. These (meth) acrylates may be used alone or in combination of two or more.

As the photopolymerization initiator, a photopolymerization initiator known in the industry can be used in a blending amount well known in the industry, so detailed description thereof will be omitted.

The thickness of the adhesive layer (after curing of the adhesive) is preferably 0.1 μm to 3.0 μm. A desired distance L can be achieved by applying the adhesive so as to have such a thickness.

Details of the adhesive are described in, for example, JP-A-2018-017996. The description of this publication is incorporated herein by reference.

E. Conductive layer or isotropic base material with conductive layer The conductive layer is made of any suitable base material by any suitable film forming method (for example, vacuum deposition method, sputtering method, CVD method, ion plating method, spray method, etc.). It can be formed by forming a metal oxide film on top of it. Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Of these, indium-tin composite oxide (ITO) is preferable.

When the conductive layer contains a metal oxide, the thickness of the conductive layer is preferably 50 nm or less, more preferably 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

The conductive layer may be transferred from the base material to the second retardation layer to form a constituent layer of a polarizing plate with a retardation layer by itself, or a laminate with the base material (base material with a conductive layer). It may be laminated on the second retardation layer. Preferably, the substrate is optically isotropic, and therefore the conductive layer can be used as an isotropic substrate with a conductive layer in a polarizing plate with a retardation layer.

Any suitable isotropic base material can be adopted as the optically isotropic base material (isotropic base material). Examples of the material constituting the isotropic base material include a material having a resin having no conjugate system such as a norbornene resin and an olefin resin as a main skeleton, and an acrylic resin having a cyclic structure such as a lactone ring and a glutarimide ring. Examples include the material contained in the main chain. When such a material is used, when an isotropic base material is formed, the expression of the phase difference due to the orientation of the molecular chains can be suppressed to be small. The thickness of the isotropic substrate is preferably 50 μm or less, more preferably 35 μm or less. The lower limit of the thickness of the isotropic substrate is, for example, 20 μm.

The conductive layer and / or the conductive layer of the isotropic base material with the conductive layer can be patterned as needed. By patterning, a conductive portion and an insulating portion can be formed. As a result, electrodes can be formed. The electrode can function as a touch sensor electrode that senses contact with the touch panel. As the patterning method, any suitable method can be adopted. Specific examples of the patterning method include a wet etching method and a screen printing method.

F. Image display device The polarizing plate with a retardation layer according to the above items A to E can be applied to an image display device. Therefore, the present invention includes an image display device using such a polarizing plate with a retardation layer. Typical examples of the image display device include a liquid crystal display device and an electroluminescence (EL) display device (for example, an organic EL display device and an inorganic EL display device). The image display device according to the embodiment of the present invention includes the polarizing plate with a retardation layer according to the above items A to E on the visible side thereof. The polarizing plate with a retardation layer is laminated so that the retardation layer is on the image display cell side (for example, a liquid crystal cell, an organic EL cell, an inorganic EL cell) (so that the polarizer is on the visual recognition side). In one embodiment, the image display device is an organic EL display device. In one embodiment, the image display device has a curved shape (substantially a curved display screen) and / or is bendable or bendable. In such an image display device, the effect of the polarizing plate with a retardation layer of the present invention becomes remarkable.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.
(1) Thickness The thickness of 10 μm or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). The thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu, product name “KC-351C”).
(2) Warpage The polarizing plates with retardation layers obtained in Examples and Comparative Examples were cut out to a size of 140 mm × 70 mm. At this time, it was cut out so that the absorption axis direction of the polarizer was the long side direction. On the other hand, a polyimide film (thickness 50 μm or 75 μm) was cut out to a size of 140 mm × 70 mm. The cut out polarizing plate with a retardation layer and the polyimide film were placed under the conditions of 23 ° C. and 55% RH for 1 day or more to control the humidity. The humidity-controlled polarizing plate with a retardation layer and the polyimide film were bonded together via an adhesive layer of the polarizing plate with a retardation layer to prepare a test sample. The test sample was subjected to a humidification test under the conditions of 20 ° C. and 98% RH for 24 hours. The amount of warpage of the test sample before and after the humidification test was measured. When the test sample was allowed to stand on a flat surface, the height of the highest portion from the flat surface was defined as the amount of warpage. Further, the case where the warp is convex toward the polyimide film side is represented by "positive (+)", and the case where the warp is convex toward the polarizing plate with a retardation layer is represented by "negative (-)". The amount of warpage before the humidification test was defined as "warp amount 1", and the amount of warpage after the humidification test was defined as "warp amount 2". The amount of warpage was calculated from the following formula, and the absolute value was used as an evaluation index.
Warp amount = (warp amount 1-warp amount 2)

[Example 1]
1. 1. Preparation of polarizing plate A-PET (amorphous-polyethylene terephthalate) film (manufactured by Mitsubishi Resin Co., Ltd., trade name: NovaClear SH046, thickness 200 μm) is prepared as a base material, and the surface is subjected to corona treatment (58 W / m2 / min). did. On the other hand, 1 wt% of acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gosefima Z200, degree of polymerization 1200, degree of saponification 99.0% or more, degree of acetacetyl modification 4.6%) is added. PVA (polymerization degree 4200, saponification degree 99.2%) was prepared, applied so that the film thickness after drying was 12 μm, and dried by hot air drying in an atmosphere of 60 ° C. for 10 minutes. A laminate having a PVA-based resin layer provided on the material was produced. Next, this laminate was first stretched 2.0 times in air at 130 ° C. to obtain a stretched laminate. Next, a step of insolubilizing the PVA-based resin layer in which the PVA molecules contained in the stretched laminate were oriented was performed by immersing the stretched laminate in a boric acid insoluble aqueous solution having a liquid temperature of 30 ° C. for 30 seconds. The boric acid insolubilized aqueous solution in this step had a boric acid content of 3% by weight based on 100% by weight of water. A colored laminate was produced by dyeing this stretched laminate. The colored laminate is obtained by immersing the stretched laminate in a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 ° C., so that iodine is adsorbed on the PVA-based resin layer contained in the stretched laminate. The iodine concentration and immersion time were adjusted so that the simple substance transmittance of the obtained polarizer was 44.5%. Specifically, the staining solution had an iodine concentration in the range of 0.08 to 0.25% by weight and a potassium iodide concentration in the range of 0.56 to 1.75% by weight using water as a solvent. .. The ratio of iodine to potassium iodide concentrations was 1: 7. Next, a step of cross-linking the PVA molecules of the PVA-based resin layer on which iodine was adsorbed was performed by immersing the colored laminate in a boric acid cross-linked aqueous solution at 30 ° C. for 60 seconds. The boric acid crosslinked aqueous solution in this step had a boric acid content of 3% by weight based on 100% by weight of water and a potassium iodide content of 3% by weight based on 100% by weight of water. Further, the obtained colored laminate was stretched 2.7 times in the same direction as the above stretching in air at a stretching temperature of 70 ° C. in a boric acid aqueous solution, and the final stretching ratio was 5.4. In doubling, a substrate / polarizer laminate was obtained. The thickness of the polarizer was 5 μm. The boric acid crosslinked aqueous solution in this step had a boric acid content of 6.5% by weight based on 100% by weight of water and a potassium iodide content of 5% by weight based on 100% by weight of water. The obtained laminate was taken out from the boric acid aqueous solution, and the boric acid adhering to the surface of the polarizer was washed with an aqueous solution having a potassium iodide content of 2% by weight based on 100% by weight of water. The washed laminate was dried with warm air at 60 ° C.
COP-HC film (manufactured by Nippon Zeon Co., Ltd., product name "ZD12-099063UHC": cycloolefin-based film with a thickness of 26 μm) on the polarizer surface of the laminate of the substrate / polarizer obtained above via a PVA-based adhesive. A hard coat layer having a thickness of 2 μm was formed on the film), and a laminate having a protective layer (COP-HC film) / polarizer / resin base material was obtained. Further, the resin base material was peeled off from this laminate to obtain a laminate (polarizing plate) having a protective layer (COP-HC film) / polarizer configuration. The coefficient of linear expansion of the protective layer (COP-HC film) in the direction of the polarizer absorption axis was 0.8 × ^10-5 / ° C.

2. 2. Preparation of First Phase Difference Layer and Second Phase Difference Layer 10 g of a polymerizable liquid crystal (manufactured by BASF, trade name "Pariocolor LC242", represented by the following formula) showing a nematic liquid crystal phase, and the polymerizable liquid crystal compound. A liquid crystal composition (coating liquid) was prepared by dissolving 3 g of a photopolymerization initiator (manufactured by BASF: trade name “Irgacure 907”) in 40 g of toluene.

The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed with a rubbing cloth and subjected to an orientation treatment. The direction of the alignment treatment was set to be 15 ° when viewed from the visual side with respect to the direction of the absorption axis of the polarizer when the polarizing plate was attached. The liquid crystal coating liquid was applied to the alignment-treated surface with a bar coater, and the liquid crystal compound was oriented by heating and drying at 90 ° C. for 2 minutes. The liquid crystal layer thus formed was irradiated with light of 1 mJ / cm ² using a metal halide lamp, and the liquid crystal layer was cured to form a liquid crystal oriented solidified layer A on the PET film. The thickness of the liquid crystal oriented solidified layer A was 2.5 μm, and the in-plane retardation Re (550) was 270 nm. Further, the liquid crystal oriented solidified layer A had a refractive index distribution of nx> ny = nz. The liquid crystal oriented solidified layer A was used as the first retardation layer.
On the PET film in the same manner as above, except that the coating thickness was changed and the orientation treatment direction was set to be 75 ° when viewed from the visual side with respect to the direction of the absorber's absorption axis. A liquid crystal oriented solidified layer B was formed. The thickness of the liquid crystal oriented solidified layer B was 1.5 μm, and the in-plane retardation Re (550) was 140 nm. Further, the liquid crystal oriented solidified layer B had a refractive index distribution of nx> ny = nz. The liquid crystal oriented solidifying layer B was used as the second retardation layer.

3. 3. Fabrication of polarizing plate with retardation layer 1. On the polarizer surface of the polarizing plate obtained in 2. above. The liquid crystal oriented solidified layer A (first retardation layer) and the liquid crystal oriented solidified layer B (second retardation layer) obtained in the above were transferred in this order. At this time, the angle between the absorption axis of the polarizer and the slow axis of the alignment solidification layer A is 15 °, and the angle between the absorption axis of the polarizer and the slow axis of the alignment solidification layer B is 75 °. Transferred (bonded). Each transfer (bonding) was carried out via an ultraviolet curable adhesive (thickness 1.0 μm). Finally, an acrylic pressure-sensitive adhesive layer (thickness 15 μm) was placed on the surface of the orientation solidification layer B (second retardation layer). In this way, it has a structure of a protective layer / adhesive / polarizing element / first adhesive layer / first retardation layer / second adhesive layer / second retardation layer / adhesive layer. A polarizing plate with a phase difference layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 55 μm. The obtained polarizing plate with a retardation layer was used for the evaluation of the warp of (2) above. In the evaluation of warpage, "Kapton (registered trademark)" (thickness 50 μm) manufactured by DuPont Toray Industries, Inc. was used as the polyimide film. The results are shown in Table 1.

[Example 2]
A polarizing plate with a retardation layer was produced in the same manner as in Example 1. A polarizing plate with a retardation layer was subjected to the evaluation of the warp of (2) above in the same manner as in Example 1 except that "UPIREX" (thickness 50 μm) manufactured by Ube Industries, Ltd. was used as the polyimide film. The results are shown in Table 1.

[Example 3]
A polarizing plate with a retardation layer was produced in the same manner as in Example 1. A polarizing plate with a retardation layer was used for the evaluation of the warp of (2) above in the same manner as in Example 1 except that "UPIREX" (thickness 75 μm) manufactured by Ube Industries, Ltd. was used as the polyimide film. The results are shown in Table 1.

[Example 4]
A long roll of a PVA-based resin film having a thickness of 30 μm is uniaxially stretched in the long direction so that the total stretching ratio becomes 6.0 times by a roll stretching machine, and at the same time, it is swelled, dyed, crosslinked and washed. Finally, a drying treatment was performed to prepare a polarizer having a thickness of 12 μm. A COP-HC film similar to that in Example 1 was attached to one surface of the obtained polarizer as a protective layer on the visible side via a PVA-based adhesive. Further, a triacetyl cellulose (TAC) film (manufactured by Konica Minolta, product name "KC2CT1", thickness 20 μm) is attached to the other surface of the polarizing element via a PVA-based adhesive, and a protective layer (COP-HC) is attached. A polarizing plate having a structure of (film) / polarizer / protective layer (TAC film) was obtained. The following procedure is the same as in Example 1 to form a first retardation layer, a second retardation layer and an adhesive layer on the TAC film side, and a visible side protective layer / adhesive / polarizer / adhesive / A polarizing plate with a retardation layer having a structure of a protective layer / a first adhesive layer / a first retardation layer / a second adhesive layer / a second retardation layer / an adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 82 μm. The obtained polarizing plate with a retardation layer was used for the evaluation of the warp of (2) above. In the evaluation of warpage, "UPIREX" (thickness 50 μm) manufactured by Ube Industries, Ltd. was used as the polyimide film. The results are shown in Table 1.

[Example 5]
A polarizing plate with a retardation layer was produced in the same manner as in Example 4. A polarizing plate with a retardation layer was used for the evaluation of the warp of (2) above in the same manner as in Example 4 except that "UPIREX" (thickness 75 μm) manufactured by Ube Industries, Ltd. was used as the polyimide film. The results are shown in Table 1.

[Example 6]
Except for the fact that an acrylic resin film (manufactured by Toyo Kohan Co., Ltd., product name "RV-20UB", thickness 20 μm) was used instead of the COP-HC film as the protective layer, and that the thickness of the adhesive layer was 50 μm. Made a polarizing plate with a retardation layer in the same manner as in Example 1. The total thickness of the obtained polarizing plate with a retardation layer was 81 μm. The coefficient of linear expansion of the protective layer (acrylic film) in the direction of the polarizer absorption axis was 3.9 × 10 ^-5 / ° C. The obtained polarizing plate with a retardation layer was subjected to the evaluation of the warp of (2) above in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A polarizing plate with a retardation layer was produced in the same manner as in Example 6 except that a different acrylic resin film (manufactured by Toyo Kohan Co., Ltd., product name “HX-40UC”, thickness 40 μm) was used as the protective layer. The total thickness of the obtained polarizing plate with a retardation layer was 101 μm. The coefficient of linear expansion of the protective layer (acrylic film) in the direction of the polarizer absorption axis was 3.9 × 10 ^-5 / ° C. The obtained polarizing plate with a retardation layer was subjected to the evaluation of the warp of (2) above in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
A long roll of a PVA-based resin film having a thickness of 55 μm is uniaxially stretched in the long direction so that the total stretching ratio becomes 6.0 times by a roll stretching machine, and at the same time, it is swelled, dyed, crosslinked and washed. Finally, a drying treatment was performed to prepare a polarizer having a thickness of 22 μm. A TAC-HC film (manufactured by Konica Minolta, product name "KC4UYW": TAC film having a thickness of 40 μm) was formed with a hard coat layer having a thickness of 7 μm on one surface of the obtained polarizer via a PVA-based adhesive. Things) were pasted together. Further, an acrylic resin film (manufactured by Toyo Kogyo Co., Ltd., product name "RV-20UB", thickness 20 μm) is attached to the other surface of the polarizing element via a PVA adhesive, and a protective layer (TAC-HC) is attached. A polarizing plate having a structure of (film) / polarizer / protective layer (acrylic film) was obtained. The following procedure is the same as in Example 1 to form a first retardation layer, a second retardation layer and an adhesive layer on the acrylic film side, and a visible side protective layer / adhesive / polarizer / adhesive / A polarizing plate with a retardation layer having a structure of a protective layer / a first adhesive layer / a first retardation layer / a second adhesive layer / a second retardation layer / an adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 110 μm. The coefficient of linear expansion of the humidifying line in the polarizing element absorption axis direction of the visible side protective layer (TAC-HC film) was 6.3 × ^10-5 / ° C. The obtained polarizing plate with a retardation layer was subjected to the evaluation of the warp of (2) above in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
A polarizing plate with a retardation layer was produced in the same manner as in Comparative Example 2. A polarizing plate with a retardation layer was used for the evaluation of the warp of (2) above in the same manner as in Comparative Example 2 except that "UPIREX" (thickness 50 μm) manufactured by Ube Industries, Ltd. was used as the polyimide film. The results are shown in Table 1.

[Comparative Example 4]
A polarizing plate with a retardation layer was produced in the same manner as in Comparative Example 2. A polarizing plate with a retardation layer was used for the evaluation of the warp of (2) above in the same manner as in Comparative Example 2 except that "UPIREX" (thickness 75 μm) manufactured by Ube Industries, Ltd. was used as the polyimide film. The results are shown in Table 1.

[Comparative Example 5]
Instead of COP-HC film, TAC-HC film (manufactured by Konica Minolta, product name "KC2UA-HC": TAC film with a thickness of 25 μm and a hard coat layer with a thickness of 7 μm formed) is used as a protective layer on the visual side. Except for the fact that a different TAC film (manufactured by Konica Minolta, product name "KC2UA", thickness 25 μm) was used as the protective layer on the side opposite to the visible side, and the thickness of the adhesive layer was set to 30 μm. A polarizing plate with a retardation layer was produced in the same manner as in Example 4. The total thickness of the obtained polarizing plate with a retardation layer was 105 μm. The coefficient of linear expansion of the humidifying line in the polarizing element absorption axis direction of the visible side protective layer (TAC-HC film) was 6.3 × ^10-5 / ° C. The obtained polarizing plate with a retardation layer was subjected to the evaluation of the warp of (2) above in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 6]
Instead of the COP-HC film, a TAC-HC film (manufactured by Konica Minolta, product name "KC2UA-HC": a TAC film having a thickness of 25 μm and a hard coat layer having a thickness of 7 μm formed) is used as a protective layer on the visual side. A polarizing plate with a retardation layer was produced in the same manner as in Example 1 except for the above. The total thickness of the obtained polarizing plate with a retardation layer was 58 μm. The coefficient of linear expansion of the protective layer (TAC-HC film) in the direction of the polarizer absorption axis was 6.3 × ^10-5 / ° C. The obtained polarizing plate with a retardation layer was subjected to the evaluation of the warp of (2) above in the same manner as in Example 1. The results are shown in Table 1.

[Evaluation]
As is clear from Table 1, according to the embodiment of the present invention, the coefficient of linear expansion of the humidified line in the direction of the polarizing element absorption axis of the visible side protective layer, and from the midpoint of the total thickness to the visible side surface of the visible side protective layer. By optimizing the distance, it is possible to remarkably suppress the warp when the polarizing plate with a retardation layer is attached to the polyimide film. Since the polyimide film can correspond to an image display device whose mechanical properties are bendable or bendable, the polarizing plate with a retardation layer according to the embodiment of the present invention warps when applied to a bendable or bendable image display device. It can be seen that can be significantly suppressed.

The polarizing plate with a retardation layer of the present invention is suitably used as a circular polarizing plate for a liquid crystal display device, an organic EL display device, and an inorganic EL display device.

10 Polarizing plate 11 Polarizer 12 Protective layer 13 Protective layer 21 First retardation layer 22 Second retardation layer 31 First adhesive layer 32 Second adhesive layer 100 Polarizing plate with retardation layer

Claims

A polarizing plate containing a polarizing element and a protective layer at least on the visible side of the polarizing element, and a first retardation layer bonded to the side opposite to the visible side of the polarizing plate via a first adhesive layer. , A second retardation layer bonded to the first retardation layer via a second adhesive layer, and the second retardation layer provided on the opposite side of the first retardation layer. With an adhesive layer,
The coefficient of linear expansion of the humidifying line in the absorption axis direction of the polarizer of the protective layer on the visual side is 6 × 10 -5 /% RH or less.
The distance from the midpoint of the total thickness to the visible surface of the visible protective layer is 45 μm or less.
Polarizing plate with retardation layer.
The polarizing plate with a retardation layer according to claim 1, wherein each of the first retardation layer and the second retardation layer is an orientation-solidifying layer of a liquid crystal compound.
The polarizing plate with a retardation layer according to claim 1 or 2, wherein the total thickness is 100 μm or less.
The Re (550) of the first retardation layer is 200 nm to 300 nm, and the angle formed by the slow axis thereof and the absorption axis of the polarizer is 10 ° to 20 °.
The Re (550) of the second retardation layer is 100 nm to 190 nm, and the angle formed by the slow axis thereof and the absorption axis of the polarizer is 70 ° to 80 °.
The polarizing plate with a retardation layer according to any one of claims 1 to 3.
The invention according to any one of claims 1 to 4, wherein the absolute value of the amount of warpage when the film is attached to a polyimide film via the pressure-sensitive adhesive layer and left at 20 ° C. and 98% RH for 24 hours is 30 mm or less. Polarizing plate with retardation layer.
An image display device including the polarizing plate with a retardation layer according to any one of claims 1 to 5.
The image display device according to claim 6, which is an organic electroluminescence display device.