JP2023075748A - Polarizing plate with retardation layer, and image display device using the same - Google Patents

Abstract

To provide a polarizing plate with a retardation layer which offers superior light resistance and durability.SOLUTION: A polarizing plate with a retardation layer according to an embodiment of the present invention comprises a polarizing plate including a polarizer and a retardation layer, and is rectangular. A long-side direction of the polarizing plate with the retardation layer is parallel to a slow axis direction of the retardation layer.SELECTED DRAWING: Figure 1

Description

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

2. Description of the Related Art In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices) have rapidly spread. Polarizing plates and retardation plates are typically used in image display devices. 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). As the demand for thinner image display devices increases, the demand for thinner polarizing plates with retardation layers also increases. For the purpose of thinning the polarizing plate with the retardation layer, thinning of the retardation film is progressing. Moreover, in order to evaluate the durability of the retardation film, the manufactured retardation film is subjected to various evaluation tests. A thin retardation film may have a problem of deterioration in durability (for example, light resistance). Therefore, a polarizing plate with a retardation layer having high light resistance and durability is desired.

Japanese Patent No. 3325560

The present invention has been made to solve the conventional problems described above, and a main object thereof is to provide a thin polarizing plate with a retardation layer having high light resistance and durability.

The retardation layer-attached polarizing plate of the present invention is a rectangular retardation layer-attached polarizing plate having a polarizing plate containing a polarizer and a retardation layer, wherein the long side direction of the retardation layer-attached polarizing plate and the It is parallel to the slow axis direction of the retardation layer.
In one embodiment, the polarizer has a boric acid content of 25% by weight or less.
In one embodiment, the angle between the absorption axis of the polarizer and the long-side direction of the retardation layer-attached polarizing plate is 35° to 55°.
In one embodiment, the ratio of the length of the long side to the length of the short side of the retardation layer-attached polarizing plate is 1.1 to 2.2.
In one embodiment, the retardation layer is an aligned and fixed layer of a liquid crystal compound having a circularly polarized light function or an elliptically polarized light function.
In one embodiment, the polarizing plate with the upper retardation layer has a dimensional shrinkage of 0.076% or more in the short side direction when irradiated with xenon light for 100 hours under conditions of 50° C. and 50% RH.
In one embodiment, the total thickness of the retardation layer-attached polarizing plate is 60 μm or less.
An image display device is provided in another aspect of the present invention. This image display device includes the retardation layer-attached polarizing plate.
In one embodiment, the image display device is an organic electroluminescence display device or an inorganic electroluminescence display device.

According to the embodiment of the present invention, it is possible to provide a thin polarizing plate with a retardation layer having high light resistance and durability.

1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention; FIG.

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

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the in-plane direction orthogonal to the slow axis (i.e., fast axis direction) and "nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re(λ)” is an in-plane retardation measured at 23° C. with light having a wavelength of λ nm. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) Thickness direction retardation (Rth)
“Rth(λ)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of λ nm. For example, “Rth(550)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of 550 nm. Rth(λ) is determined by the formula: Rth(λ)=(nx−nz)×d, where d (nm) is the thickness of the layer (film).
(4) Nz Coefficient The Nz coefficient is obtained by Nz=Rth/Re.
(5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to a reference direction. Thus, for example, "45°" means ±45°.

A. Overall Configuration of Retardation Layer-Equipped Polarizing Plate FIG. 1 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to one embodiment of the present invention. A polarizing plate 100 with a retardation layer in the illustrated example has a polarizing plate 10, a retardation layer 20, and an adhesive layer 30 in this order from the viewing side. Polarizing plate 10 typically includes polarizer 11 and protective layer 12 disposed on the viewing side of polarizer 11 . Depending on the purpose, another protective layer (not shown) may be provided on the opposite side of the polarizer 11 from the viewing side (the side of the polarizer 11 on which the protective layer 12 is not laminated). The retardation layer 20 is typically an alignment fixed layer of a liquid crystal compound having a circularly polarized light function or an elliptical polarized light function (hereinafter sometimes simply referred to as a liquid crystal alignment fixed layer). The retardation layer-attached polarizing plate is provided with an adhesive layer 30 as the outermost layer, and can be attached to an image display device (substantially, an image display cell). Practically, it is preferable that a release liner is temporarily attached to the surface of the pressure-sensitive adhesive layer 30 until the polarizing plate is used. By temporarily attaching the release liner, the pressure-sensitive adhesive layer can be appropriately protected.

The retardation layer-attached polarizing plate of the embodiment of the present invention is rectangular and has short sides and long sides. The ratio of the length of the long side to the length of the short side of the polarizing plate with a retardation layer (long side length/short side length) is, for example, a value exceeding 1, preferably 1.1 to 3.0. 0, more preferably 1.3 to 2.7, even more preferably 1.5 to 2.5. When the ratio of the length of the long side to the length of the short side of the polarizing plate with a retardation layer is within the above range, deterioration such as deterioration of the retardation due to sunlight is suppressed, and high light resistance and durability are obtained. A polarizing plate with a retardation layer can be provided.

In the embodiment of the present invention, the long side direction of the retardation layer-attached polarizing plate 100 is parallel to the slow axis direction of the retardation layer 20 . As described above, the retardation layer-attached polarizing plate may undergo dimensional shrinkage under the conditions of the xenon light irradiation test. This dimensional shrinkage tends to be greater in the short side direction, and the retardation layer may also shrink more in the short side direction along with the shrinkage. As a result, the phase difference may decrease and the reliability may decrease. Since the long side direction of the polarizing plate with retardation layer 100 and the slow axis direction of the retardation layer 20 are parallel, the uniaxiality of the retardation layer increases as the polarizing plate with retardation layer shrinks. , and the phase difference may increase. Therefore, a decrease in retardation due to dimensional shrinkage and an increase in retardation due to an increase in uniaxiality can be balanced. As a result, it is possible to provide a polarizing plate with a retardation layer that suppresses deterioration such as a decrease in retardation due to a xenon light irradiation test and has high light resistance and durability. In the present specification, "parallel" does not only mean being completely parallel, but the angle formed by the long side direction of the retardation layer-attached polarizing plate and the slow axis direction of the retardation layer is substantially parallel, for example, -5°. Including the case of ~5°.

The angle between the absorption axis of the polarizer 11 and the long side direction of the retardation layer-attached polarizing plate 100 is preferably 35° to 55°, more preferably 40° to 50°, and still more preferably 42°. ∼48°, particularly preferably about 45°. When the angle formed by the absorption axis of the polarizer 11 and the long side direction of the polarizing plate 100 with a retardation layer is within the above range, deterioration such as a decrease in retardation due to sunlight can be further suppressed, and high light resistance and durability can be obtained. It is possible to provide a polarizing plate with a retardation layer having properties.

The dimensional shrinkage rate in the short side direction of the retardation layer-attached polarizing plate when irradiated with xenon light for 100 hours under conditions of 55° C. and 50% RH is preferably 0.076% or more, more preferably 0.090%. or more, more preferably 0.12% or more. The dimensional shrinkage in the short side direction is, for example, 0.16% or less. When the dimensional shrinkage in the short side direction is within the above range, the reduction in retardation due to dimensional shrinkage and the improvement in retardation due to the increase in uniaxiality can be balanced. As a result, it is possible to provide a polarizing plate with a retardation layer that suppresses deterioration such as a decrease in retardation due to a xenon light irradiation test and has high light resistance and durability. In this specification, the dimensional shrinkage rate in the short side direction refers to the polarizing plate with a retardation layer after irradiation with xenon light for 100 hours under the conditions of a black panel temperature of 55 ° C. and a humidity of 55% RH. The shrinkage distance (mm) in the short side direction of the polarizing plate was measured with an XY length measuring machine, and the shrinkage distance was used to calculate the short side direction of the polarizing plate with the retardation layer before and after the xenon light irradiation test. Shrinkage rate.

Shrinkage ratio in the short side direction=(shrinkage distance in the short side direction)/(length of the short side before xenon light irradiation)×100

The retardation layer 20 is preferably a liquid crystal alignment fixed layer. The retardation layer 20 may be a single layer, or may have a laminated structure of a first liquid crystal alignment fixed layer and a second liquid crystal alignment fixed layer.

The retardation layer-attached polarizing plate may be further provided with a retardation layer different from the retardation layer 20 and/or a conductive layer or an isotropic substrate with a conductive layer (neither is shown). Another retardation layer is typically provided between the retardation layer 20 and the adhesive layer 30 (that is, outside the retardation layer 20). Another retardation layer typically exhibits a refractive index characteristic of nz>nx=ny. A conductive layer or an isotropic substrate with a conductive layer is typically provided between the retardation layer 20 and the adhesive layer 30 . Another retardation layer and a conductive layer or an isotropic substrate with a conductive layer are typically provided in this order from the retardation layer 20 side. The other retardation layer and the conductive layer or the isotropic substrate with the conductive layer are arbitrary layers provided as necessary, and one or both of them may be omitted. When a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a retardation layer is a so-called inner touch panel type in which a touch sensor is incorporated between the image display cell (e.g., organic EL cell) and the polarizing plate. It can be applied to input display devices.

The optical properties (for example, refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the separate retardation layer can be appropriately set according to the purpose.

The total thickness of the retardation layer-attached polarizing plate is preferably 100 µm or less, more preferably 60 µm or less, still more preferably 55 µm or less, even more preferably 50 µm or less, and particularly preferably 40 µm or less. . The total thickness can be, for example, 28 μm or more. According to the embodiment of the present invention, a polarizing plate with such an extremely thin retardation layer can be realized. In addition, such a retardation layer-attached polarizing plate can have extremely excellent flexibility and bending durability. Therefore, such a retardation layer-attached polarizing plate can be particularly preferably applied to a curved image display device and/or a bendable or foldable image display device. In addition, the total thickness of the polarizing plate with a retardation layer means the polarizing plate, the retardation layer (when another retardation layer is present, the retardation layer and another retardation layer), and the thickness for laminating these. Refers to the total thickness of the adhesive layer or pressure-sensitive adhesive layer (that is, the total thickness of the retardation layer-attached polarizing plate is the conductive layer or the isotropic substrate with the conductive layer, and the adhesive layer 30 and its surface temporarily attached. not including the thickness of the release liner obtained).

The constituent elements of the retardation layer-attached polarizing plate will be described in more detail below.

B. Polarizing plate B-1. Polarizer A polarizer is typically composed of a polyvinyl alcohol (PVA) resin film containing a dichroic substance. The thickness of the polarizer is preferably 1 μm to 8 μm, more preferably 1 μm to 7 μm, still more preferably 2 μm to 5 μm. If the thickness of the polarizer is within such a range, it can greatly contribute to thinning the polarizing plate with the retardation layer. Furthermore, the effect of the present invention is remarkable in a thin polarizing plate with a retardation layer using such a polarizer.

The boric acid content of the polarizer is preferably 25 wt % or less, more preferably 11 wt % to 25 wt %, still more preferably 12 wt % to 25 wt %. If the boric acid content of the polarizer is in such a range, it is possible to suppress deterioration such as a decrease in retardation due to a xenon light irradiation test, and a polarizing plate with a retardation layer having high light resistance and durability can be obtained. can provide. In addition, it is possible to improve the appearance durability during heating while maintaining the ease of curl adjustment during bonding and suppressing curl during heating. The boric acid content can be calculated as the amount of boric acid contained in the polarizer per unit weight, for example, using the following formula from the neutralization method.

The iodine content of the polarizer is preferably 2% by weight or more, more preferably 2% to 10% by weight. If the iodine content of the polarizer is within such a range, the synergistic effect with the above-mentioned boric acid content can maintain the ease of curl adjustment during bonding and prevent curl during heating. It is possible to improve the appearance durability during heating while satisfactorily suppressing the As used herein, "iodine content" means the total amount of iodine contained in the polarizer (PVA-based resin film). More specifically, iodine exists in the form of iodine ions (I ⁻ ), iodine molecules (I ₂ ), polyiodine ions (I ₃ ⁻ , I ₅ ⁻ ) and the like in the polarizer. The iodine content means the amount of iodine including all these forms. The iodine content can be calculated, for example, by a calibration curve method of fluorescent X-ray analysis. The polyiodine ions are present in the polarizer in the form of a PVA-iodine complex. Absorption dichroism can be expressed in the visible light wavelength range by forming such a complex. Specifically, the complex of PVA and triiodide ion (PVA·I ₃ ⁻ ) has an absorption peak near 470 nm, and the complex of PVA and pentaiodide ion (PVA·I ₅ ⁻ ) has an absorption peak near 600 nm. has an absorption peak at As a result, polyiodine ions can absorb light in a wide range of visible light, depending on their morphology. On the other hand, iodine ions (I ⁻ ) have an absorption peak near 230 nm and are not substantially involved in the absorption of visible light. Therefore, polyiodine ions present in a complex with PVA may be primarily responsible for the absorption performance of the polarizer.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance Ts of the polarizer is preferably 40% to 48%, more preferably 41% to 46%. The degree of polarization P of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, still more preferably 99.9% or more. The single transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction. The degree of polarization is typically obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction.
Degree of polarization (%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

A polarizer can typically be made using a laminate of two or more layers. A specific example of a polarizer obtained using a laminate is a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. A polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material is obtained, for example, by applying a PVA-based resin solution to the resin base material and drying the resin base material. forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may further include stretching the laminate in air at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate. Then, any appropriate protective layer may be laminated on the release surface according to the purpose. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. These publications are incorporated herein by reference in their entireties.

A typical method for producing a polarizer is to form a laminate by forming a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate, Then, the laminate is subjected in this order to an in-air auxiliary stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process that shrinks the laminate by 2% or more in the width direction by heating while being transported in the longitudinal direction. including. As a result, it is possible to provide a polarizer that is extremely thin, has excellent optical properties, and has suppressed variations in optical properties. That is, by introducing auxiliary stretching, it becomes possible to improve the crystallinity of PVA even when PVA is coated on a thermoplastic resin, and to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process, resulting in high optical properties. can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance of the orientation of the polyvinyl alcohol molecules and deterioration of the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical properties of the polarizer obtained through treatment steps such as dyeing treatment and underwater stretching treatment in which the laminate is immersed in a liquid. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment.

B-2. Protective Layer Protective layer 12 is formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that are the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, and polysulfones. , polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based transparent resins. Thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may also be used. In addition, for example, a glassy polymer such as a siloxane-based polymer can also be used. Further, polymer films described in JP-A-2001-343529 (WO01/37007) can also be used. Materials for this film include, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in a side chain. can be used, for example, a resin composition comprising an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile/styrene copolymer. The polymer film can be, for example, an extrudate of the resin composition.

As will be described later, the polarizing plate with a retardation layer is typically arranged on the viewing side of the image display device, and the protective layer 12 is typically arranged on the viewing side. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment, if necessary. Additionally/or, the protective layer 12 may optionally be treated to improve visibility when viewed through polarized sunglasses (typically, imparting (elliptical) polarizing function, ultra-high retardation ) may be applied. By performing such processing, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the retardation layer-attached polarizing plate can also be suitably applied to an image display device that can be used outdoors.

The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm. In addition, when the surface treatment is performed, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer.

C. Retardation Layer As described above, the retardation layer 20 typically has a circular polarization function or an elliptical polarization function. The retardation layer typically exhibits a refractive index characteristic of nx>ny=nz. A retardation layer is typically provided to impart antireflection properties to a polarizing plate, and when the retardation layer is a single layer, it can function as a λ/4 plate. In this case, the in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, still more preferably 130 nm to 160 nm. Here, "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 be satisfied within a range that does not impair the effects of the present invention. The retardation layer is preferably an alignment solidified layer of a liquid crystal compound having a circularly polarized light function or an elliptically polarized light function.

When the retardation layer 20 is composed of a single layer, its thickness is preferably 0.5 μm to 7 μm, more preferably 1 μm to 5 μm. By using a liquid crystal compound, it is possible to realize an in-plane retardation equivalent to that of a resin film with a thickness much thinner than that of a resin film.

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

The retardation layer may exhibit a reverse wavelength dispersion 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 may well exhibit a flat wavelength dispersion characteristic in which the retardation value hardly changes even with the wavelength of the measurement light. In one embodiment, the retardation layer exhibits reverse wavelength dispersion characteristics. In this case, Re(450)/Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection properties can be achieved.

The angle θ between the slow axis of the retardation layer 20 and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, still more preferably about 45°. be. If the angle θ is within such a range, the use of the λ/4 plate as the retardation layer as described above will result in very good circularly polarized light properties (resulting in very good antireflection properties). A polarizing plate with a retardation layer can be obtained.

In another embodiment, the retardation layer 20 may have a laminated structure of a first liquid crystal alignment fixed layer and a second liquid crystal alignment fixed layer. In this case, one of the first liquid crystal alignment fixed layer and the second liquid crystal alignment fixed layer can function as a λ/4 plate, and the other can function as a λ/2 plate. Therefore, the thicknesses of the first liquid crystal alignment fixed layer and the second liquid crystal alignment fixed layer can be adjusted so as to obtain the desired in-plane retardation of the λ/4 plate or the λ/2 plate. For example, when the first liquid crystal alignment fixed layer functions as a λ/2 plate and the second liquid crystal alignment fixed layer functions as a λ/4 plate, the thickness of the first liquid crystal alignment fixed layer is, for example, 2.0 μm to 3.0 μm, and the thickness of the second liquid crystal alignment fixed layer is, for example, 1.0 μm to 2.0 μm. In this case, the in-plane retardation Re(550) of the first liquid crystal alignment fixed layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, still more preferably 250 nm to 280 nm. The in-plane retardation Re(550) of the second liquid crystal alignment fixed layer is as described above for the single layer.

The angle formed by the slow axis of the first liquid crystal alignment fixed layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, still more preferably about 15°. is. The angle formed by the slow axis of the second liquid crystal alignment fixed layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and more preferably about 75°. is. With such a configuration, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, and as a result, very excellent antireflection characteristics can be realized.

As described above, the retardation layer 20 is preferably an alignment fixed layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny in the resulting retardation layer can be significantly increased compared to a non-liquid crystal material. can be significantly reduced. As a result, it is possible to further reduce the thickness of the retardation layer-attached polarizing plate. As used herein, the term “liquid crystal alignment fixed layer” refers to a layer in which a liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. In addition, the "alignment fixed layer" is a concept including an alignment cured layer obtained by curing a liquid crystal monomer as described later.

The retardation layer, which is a fixed alignment layer of a liquid crystal compound, can be formed using a composition containing a polymerizable liquid crystal compound. The polymerizable liquid crystal compound contained in the composition as used herein refers to a compound having a polymerizable group and liquid crystallinity. A polymerizable group means a group involved in a polymerization reaction, preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical generated from a photopolymerization initiator, an acid, or the like.

Liquid crystalline expression may be thermotropic or lyotropic. Further, the structure of the liquid crystal phase may be nematic liquid crystal or smectic liquid crystal. Thermotropic nematic liquid crystals are preferred from the standpoint of ease of production.

In one embodiment, the single-layer retardation layer is formed using a composition containing a liquid crystal compound represented by the following formula (1).
L ¹ -SP ¹ -A ¹ -D ³ -G ¹ -D ¹ -Ar-D ² -G ² -D ⁴ -A ² -SP ² -L ² (1)

L ¹ and L ² each independently represent a monovalent organic group, and at least one of L ¹ and L ² represents a polymerizable group. Monovalent organic groups include any suitable groups. Examples of the polymerizable group represented by at least one of L ¹ and L ² include radically polymerizable groups (groups capable of radical polymerization). Any appropriate radically polymerizable group can be used as the radically polymerizable group. An acryloyl group or a methacryloyl group is preferred. An acryloyl group is preferred because it has a high polymerization rate and improves productivity. A methacryloyl group can also be used as a polymerizable group for highly birefringent liquid crystals.

SP ¹ and SP ² each independently constitute a single bond, a linear or branched alkylene group, or a linear or branched alkylene group having 1 to 14 carbon atoms —CH ₂ represents a divalent linking group in which one or more of - are substituted with -O-; The linear or branched alkylene group having 1 to 14 carbon atoms preferably includes methylene group, ethylene group, propylene group, butylene group, pentylene group and hexylene group.

A ¹ and A ² each independently represent an alicyclic hydrocarbon group or an aromatic ring substituent. A ¹ and A ² are preferably aromatic ring substituents having 6 or more carbon atoms or cycloalkylene rings having 6 or more carbon atoms.

D ¹ , D ² , D ³ and D ⁴ each independently represent a single bond or a divalent linking group. Specifically, D ¹ , D ² , D ³ and D ⁴ are a single bond, —O—CO—, —C(=S)O—, —CR ¹ R ² —, —CR ¹ R ² —CR ^{3R 4} -, -O-CR ¹ R ² -, -CR ¹ R ² -O-CR ³ R ⁴ -, -CO-O-CR ¹ R ² -, -O-CO-CR ¹ R ² -, -CR ¹ R ² -O-CO-CR ³ R ⁴ -, -CR ¹ R ² -CO-O-CR ³ R ⁴ -, -NR ¹ -CR ² R ³ -, or -CO-NR ¹ - represents However, at least one of D ¹ , D ² , D ³ and D ⁴ represents -O-CO-. Among them, D ³ is preferably -O-CO-, and D ³ and D ⁴ are more preferably -O-CO-. D ¹ and D ² are preferably single bonds. R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms.

G ¹ and G ² each independently represent a single bond or an alicyclic hydrocarbon group. Specifically, G ¹ and G ² may represent an unsubstituted or substituted divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms. In addition, one or more —CH ₂ — constituting the alicyclic hydrocarbon group may be substituted with —O—, —S— or —NH—. G ¹ and G ² preferably represent a single bond.

Ar represents an aromatic hydrocarbon ring or an aromatic heterocycle. Ar represents, for example, an aromatic ring selected from the group consisting of groups represented by the following formulas (Ar-1) to (Ar-6). In the following formulas (Ar-1) to (Ar-6), *1 represents the bonding position with ^D1 , and *2 represents the bonding position with ^D2 .

In formula (Ar-1), Q ¹ represents N or CH, and Q ² represents -S-, -O-, or -N(R ⁵ )-. R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In formulas (Ar-1) to (Ar-6), Z ¹ , Z ² and Z ³ each independently represents a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, and 3 carbon atoms. represents a monovalent alicyclic hydrocarbon group of up to 20, a monovalent aromatic hydrocarbon group of 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitro group, -NR ⁶ R ⁷ or -SR ⁸ . R ⁶ to R ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Z ¹ and Z ² may combine with each other to form a ring. The ring may be an alicyclic, heterocyclic or aromatic ring, preferably an aromatic ring. The formed ring may be substituted with a substituent.

In formulas (Ar-2) and (Ar-3), A ³ and A ⁴ are each independently a group consisting of -O-, -N(R ⁹ )-, -S- and -CO- represents a group selected from the above, and R ⁹ represents a hydrogen atom or a substituent. Examples of the substituent represented by R ⁹ include the same substituents that Y ¹ in the above formula (Ar-1) may have.

In formula (Ar-2), X represents a hydrogen atom or an unsubstituted or substituted group 14 to group 16 nonmetallic atom. Examples of the nonmetallic atoms of groups 14 to 16 represented by X include an oxygen atom, a sulfur atom, an unsubstituted or substituted nitrogen atom, and an unsubstituted or substituted carbon atom. Examples of the substituent include the same substituents that Y ¹ in the above formula (Ar-1) may have.

In formula (Ar-3), D ⁵ and D ⁶ are each independently a single bond, -O-CO-, -C(=S)O-, -CR ¹ R ² -, -CR ¹ R ² -CR ³ R ⁴ -, -O-CR ¹ R ² -, -CR ¹ R ² -O-CR ³ R ⁴ -, -CO-O-CR ¹ R ² -, -O-CO-CR ¹ R ² -, -CR ¹ R ² -O-CO-CR ³ R ⁴ -, -CR ¹ R ² -CO-O-CR ³ R ⁴ -, -NR ¹ -CR ² R ³ -, or -CO-NR ¹ represents -. R ¹ , R ² , R ³ and R ⁴ are as described above.

In formula (Ar-3), SP ³ and SP ⁴ are each independently a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a linear chain having 1 to 12 carbon atoms. divalent in which one or more —CH ₂ — constituting a branched or branched alkylene group is substituted with —O—, —S—, —NH—, —N(Q)—, or —CO— and Q represents a polymerizable group.

In formula (Ar-3), L ³ and L ⁴ each independently represent a monovalent organic group, and at least one of L ³ and L ⁴ and L ¹ and L ² in formula (1) above is represents a polymerizable group.

In formulas (Ar-4) to (Ar-6), Ax is an organic group having 2 to 30 carbon atoms and having at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocyclic rings. represents In formulas (Ar-4) to (Ar-6), Ax preferably has an aromatic heterocyclic ring, more preferably a benzothiazole ring. In formulas (Ar-4) to (Ar-6), Ay is a hydrogen atom, an unsubstituted or optionally substituted alkyl group having 1 to 6 carbon atoms, or an aromatic hydrocarbon ring and aromatic represents an organic group having 2 to 30 carbon atoms and having at least one aromatic ring selected from the group consisting of heterocyclic rings. In formulas (Ar-4) to (Ar-6), Ay preferably represents a hydrogen atom.

In formulas (Ar-4) to (Ar-6), Q ³ represents a hydrogen atom or an unsubstituted or optionally substituted alkyl group having 1 to 6 carbon atoms. In formulas (Ar-4) to (Ar-6), ^Q3 preferably represents a hydrogen atom.

Among such Ar, a group (atomic group) represented by the above formula (Ar-4) or the above formula (Ar-6) is preferable.

A specific example of the liquid crystal compound represented by Formula (1) is disclosed in International Publication No. 2018/123551. The description of the publication is incorporated herein by reference. These compounds may be used alone or in combination of two or more.

A composition containing a liquid crystal compound preferably contains a polymerization initiator. Any appropriate polymerization agent can be used as the polymerization initiator. A photopolymerization initiator capable of initiating a polymerization reaction by ultraviolet irradiation is preferred. Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in US Pat. No. 2,448,828), α-hydrocarbon substituted Aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketones ( US Pat. No. 3,549,367), oxadiazole compounds (US Pat. No. 4,212,970), and acylphosphine oxide compounds (JP-B-63-40799, JP-B-5-29234, JP-A-10-95788 and JP-A-10-29997). The description of the publication is incorporated herein by reference. Only one type of polymerization initiator may be used, or two or more types may be used in combination.

A composition containing a liquid crystal compound preferably contains a solvent from the viewpoint of workability for forming a retardation layer. Any suitable solvent can be used as the solvent, and organic solvents are preferably used.

The composition containing the liquid crystal compound further contains any suitable other component. Examples include antioxidants such as phenolic antioxidants, liquid crystal compounds other than the above, leveling agents, surfactants, tilt angle control agents, alignment aids, plasticizers, and cross-linking agents.

The liquid crystal alignment fixed layer is formed by applying an alignment treatment to the surface of a predetermined base material, coating the surface with a composition (coating liquid) containing a liquid crystal compound, and aligning the liquid crystal compound in the direction corresponding to the alignment treatment. and fixing the orientation state. In one embodiment, the substrate is any appropriate resin film, and the liquid crystal alignment solidified layer formed on the substrate can be transferred to the surface of the polarizing plate.

Any appropriate alignment treatment may be employed as the alignment treatment. Specific examples include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical orientation treatment include magnetic orientation treatment and electric field orientation treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. Arbitrary appropriate conditions can be adopted as the processing conditions for various alignment treatments depending on the purpose.

Alignment of the liquid crystal compound is performed by treatment at a temperature at which a liquid crystal phase is exhibited depending on the type of liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned in accordance with the orientation treatment direction of the base material surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned 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.

Details of the method for forming the alignment fixed layer are described in JP-A-2006-163343. The description of the publication is incorporated herein by reference.

D. Alternative Retardation Layer As described above, the alternative retardation layer can be a so-called positive C plate whose refractive index characteristics exhibit a relationship of nz>nx=ny. By using a positive C plate as another retardation layer, it is possible to satisfactorily prevent reflection in oblique directions and widen the viewing angle of the antireflection function. In this case, the thickness direction retardation Rth (550) of the other retardation layer is preferably −50 nm to −300 nm, more preferably −70 nm to −250 nm, still more preferably −90 nm to −200 nm, particularly preferably − 100 nm to -180 nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal but also the case where nx and ny are substantially equal. That is, the in-plane retardation Re(550) of another retardation layer can be less than 10 nm.

Another retardation layer having refractive index properties of nz>nx=ny may be formed of any suitable material. Another retardation layer preferably consists of a film containing a liquid crystal material fixed in homeotropic alignment. A liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of JP-A-2002-333642. In this case, the thickness of the separate retardation layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, still more preferably 0.5 μm to 5 μm.

E. Adhesive Layer As the adhesive constituting the adhesive layer 30, any appropriate adhesive can be used. Examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, A cellulose-based pressure-sensitive adhesive and the like are included. Among these pressure-sensitive adhesives, those having excellent optical transparency, appropriate wettability, cohesiveness, and adhesion properties, and excellent weather resistance and heat resistance are preferably used. Acrylic pressure-sensitive adhesives are preferably used as those exhibiting such characteristics.

F. Conductive layer or isotropic substrate with conductive layer It may be formed by depositing a metal oxide film thereon. Examples of metal oxides include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferred.

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 substrate to the retardation layer (another retardation layer if present), and the conductive layer alone may be used as a constituent layer of the polarizing plate with the retardation layer. It may be laminated on a retardation layer (another retardation layer if present) as a laminate (substrate with conductive 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 substrate can be employed as the optically isotropic substrate (isotropic substrate). Materials constituting the isotropic base material include, for example, norbornene-based resins, olefin-based resins, and other resins that do not have a conjugated system as the main skeleton, and acrylic resins that have cyclic structures such as lactone rings and glutarimide rings. Examples include materials that are present in the main chain. By using such a material, it is possible to suppress the development of retardation due to the orientation of molecular chains when forming an isotropic base material. 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 base material is, for example, 20 μm.

The conductive layer and/or the conductive layer of the isotropic substrate with a conductive layer may be patterned as needed. The patterning may form conductive portions and insulating portions. As a result, electrodes can be formed. The electrodes may function as touch sensor electrodes that sense contact with the touch panel. Any appropriate method can be adopted as a patterning method. Specific examples of the patterning method include wet etching and screen printing.

G. Method for Producing Retardation Layer-attached Polarizing Plate The retardation layer-attached polarizing plate of the embodiment of the present invention can be produced by any appropriate method. In one embodiment, the polarizing plate with a retardation layer is a polarizing plate cut into a rectangle of a designed size and a retardation layer, and the long side direction of the rectangle and the slow axis direction of the retardation layer are parallel. can be made by laminating via any suitable adhesive. When laminating the polarizing plate and the retardation layer, they can be laminated so that the absorption axis of the polarizer and the slow axis of the retardation layer form a predetermined angle.

In one embodiment, the polarizing plate with a retardation layer is a large (e.g., elongated) polarizing plate and a retardation layer in which the absorption axis of the polarizer and the slow axis of the retardation layer are at a predetermined angle. Then, the retardation layer-attached polarizing plate obtained is cut into a rectangle of a designed size so that the long side direction and the slow axis of the retardation layer are parallel to each other. can be made by

H. Image Display Device The polarizing plate with a retardation layer according to the above items A to F can be applied to an image display device. Accordingly, embodiments of the present invention include image display devices using such retardation layer-attached polarizing plates. Typical examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices). An image display device according to an embodiment of the present invention includes the retardation layer-attached polarizing plate according to the above items A to F on the viewing side thereof. The retardation layer-attached polarizing plate is laminated so that the retardation layer is on the image display cell (for example, liquid crystal cell, organic EL cell, inorganic EL cell) side (so that the polarizer is on the viewing side). In one embodiment, the image display device has a curved shape (substantially a curved display screen) and/or is foldable or foldable.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. "Parts" and "%" in Examples and Comparative Examples are by weight unless otherwise specified.

(1) Thickness The thickness of 10 μm or less was measured using an interferometric film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). A thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name “KC-351C”).

(2) Retardation decrease The adhesive layer of the polarizing plate with a retardation layer obtained in Examples and Comparative Examples was laminated on a glass plate (80 mm × 150 mm) with a thickness of 0.5 mm, and the retardation measuring device ( A phase difference value (initial phase difference value) was measured using Oji Scientific Instruments Co., Ltd., product name: KOBRA). Then, using a xenon weather resistance tester (manufactured by Toyo Seiki Seisakusho, product name: Atlas Weatherometer Ci4400, inner filter: borosilicate type S, outer filter: soda lime), a BP (black panel) temperature of 55 ° C. Xenon was irradiated for 100 hours at a wavelength of 420 nm and 0.8 W/m ² under conditions of humidity of 55% RH. Next, the retardation value of the retardation layer-attached polarizing plate was measured in the same manner, and the difference from the initial retardation value was calculated as the retardation reduction amount.

(3) Dimensional Shrinkage The pressure-sensitive adhesive layers of the retardation layer-attached polarizing plates obtained in Examples and Comparative Examples were laminated on glass plates (80 mm×150 mm) having a thickness of 0.5 mm. Then, using a xenon weather resistance tester (manufactured by Toyo Seiki Seisakusho, product name: Atlas Weatherometer Ci4400, inner filter: borosilicate type S, outer filter: soda lime), a BP (black panel) temperature of 55 ° C. Xenon was irradiated for 100 hours at a wavelength of 420 nm and 0.8 W/m ² under conditions of humidity of 55% RH. Next, the dimensional shrinkage on the short side of the retardation layer-attached polarizing plate was measured using an XY measuring machine (manufactured by Mitutoyo, product name: image measuring machine QVA1517-PRO AEIM (SP)). The portion with the largest amount of shrinkage was defined as the amount of dimensional shrinkage of the retardation layer-attached polarizing plate. Also, the shrinkage ratio was calculated from the measured dimensional shrinkage using the following formula.

Shrinkage ratio in the short side direction=(shrinkage distance in the short side direction)/(length of the short side before xenon light irradiation)×100

[Example 1]
[Production Example 1: Production of polarizing plate]
1. Production of Polarizer As a thermoplastic resin substrate, a long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a water absorption of 0.75% and a Tg of about 75° C. was used. Corona treatment was applied to one side of the resin substrate.
Polyvinyl alcohol (degree of polymerization: 4,200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER Z410") mixed at 9:1: 100 weight of PVA-based resin A PVA aqueous solution (coating solution) was prepared by adding 13 parts by weight of potassium iodide.
The above PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.
The obtained laminate was uniaxially stretched 2.4 times at the free end in the machine direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment).
Then, the finally obtained polarizer is added to a dyeing bath (iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. It was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) was 43.0% or more (dyeing treatment).
Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 40°C (an aqueous solution of boric acid obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water). (crosslinking treatment).
After that, while immersing the laminate in an aqueous boric acid solution (boric acid concentration: 3.7% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70° C., the laminate is placed between rolls having different peripheral speeds in the vertical direction (longitudinal direction). Then, the film was uniaxially stretched so that the total draw ratio was 5.5 times (underwater stretching treatment).
After that, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment).
After that, while drying in an oven kept at 90° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at 75° C. for about 2 seconds (drying shrinkage treatment). The shrinkage ratio in the width direction of the laminate due to the drying shrinkage treatment was 5.2%.
Thus, a 5 μm-thick polarizer (containing 20% by weight of boric acid) was formed on the resin substrate.

2. Preparation of Polarizing Plate An HC-COP film was attached as a protective layer to the surface of the polarizer obtained above (the surface opposite to the resin substrate) via an ultraviolet curable adhesive. Specifically, the curable adhesive was applied so as to have a total thickness of 1.0 μm, and was bonded using a roll machine. After that, UV rays were applied from the protective layer side to cure the adhesive. The HC-COP film is a film in which a hard coat (HC) layer (thickness 2 μm) is formed on a cycloolefin (COP) film (manufactured by Zeon Corporation, product name “ZF12”, thickness 25 μm), and the COP film was placed on the polarizer side. Then, the resin substrate was peeled off to obtain a polarizing plate having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer.

[Production Example 2: Production of retardation layer]
55 parts by weight of the compound represented by formula (I), 25 parts by weight of the compound represented by formula (II), and 20 parts by weight of the compound represented by formula (III) were added to 400 parts by weight of cyclopentanone (CPN). After the addition, the mixture was heated to 60° C. and stirred to dissolve. After that, the solution of the above compound is returned to room temperature, and the solution of the above compound is added with 3 parts by weight of Irgacure 907 (manufactured by BASF Japan), 0.2 parts by weight of Megafac F-554 (manufactured by DIC), and p -0.1 parts by weight of methoxyphenol (MEHQ) was added and further stirred. The solution after stirring was transparent and uniform. The resulting solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition.
Further, the polyimide solution for alignment film was applied to a glass substrate having a thickness of 0.7 mm by spin coating, dried at 100° C. for 10 minutes, and then baked at 200° C. for 60 minutes to obtain a coating film. . The resulting coating film was rubbed with a commercially available rubbing device to form an alignment film.
Then, the polymerizable composition obtained above was applied to the substrate (substantially, the alignment film) by spin coating, and dried at 100° C. for 2 minutes. After cooling the obtained coating film to room temperature, it was irradiated with ultraviolet rays for 30 seconds at an intensity of 30 mW/cm ² using a high-pressure mercury lamp to obtain a retardation layer, which is an aligned and fixed layer of a liquid crystal compound. The in-plane retardation Re(550) of the retardation layer was 130 nm. In addition, Re(450)/Re(550) of the retardation layer was 0.851, showing reverse dispersion wavelength characteristics. The retardation layer can function as a λ/4 plate.

[Production Example 3: Production of another retardation layer]
20 parts by weight of a side-chain type liquid crystal polymer represented by the following chemical formula (numbers 65 and 35 in the formula indicate mol % of monomer units, and are expressed as block polymer for convenience: weight average molecular weight 5000), nematic liquid crystal phase A polymerizable liquid crystal (manufactured by BASF: trade name Paliocolor LC242) 80 parts by weight and a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) 5 parts by weight are dissolved in 200 parts by weight of cyclopentanone to form a liquid crystal. A coating solution was prepared. Then, the coating solution was applied to the vertically aligned PET substrate using a bar coater, and dried by heating at 80° C. for 4 minutes to align the liquid crystal. By irradiating the liquid crystal layer with ultraviolet rays and curing the liquid crystal layer, a second retardation layer (thickness: 3 μm) exhibiting refractive index characteristics of nz>nx=ny was formed on the substrate.

The retardation layer obtained in Production Example 2 and another retardation layer obtained in Production Example 3 were transferred in this order to the polarizer surface of the polarizing plate obtained in Production Example 1. At this time, transfer (bonding) was performed so that the angle between the absorption axis of the polarizer and the slow axis of the retardation layer obtained in Production Example 2 was 45°. Each transfer (bonding) was performed through the ultraviolet curing adhesive (thickness: 1.0 μm) used in Production Example 1. Thus, a laminate having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/retardation layer/adhesive layer/another retardation layer was produced. Next, the laminate was cut into a rectangle with a long side of 130 mm and a short side of 66 mm so that the long side direction of the retardation layer-attached polarizing plate and the slow axis of the retardation layer were parallel.

Next, a pressure-sensitive adhesive layer (thickness 5 μm) is provided on the surface of another retardation layer, and a protective layer (HC layer/COP film)/adhesive layer/polarizer/protective layer (triacetylcellulose film)/adhesive layer/position A retardation layer-attached polarizing plate having a structure of retardation layer/adhesive layer/another retardation layer/adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 100 μm. The obtained polarizing plate with a retardation layer was subjected to the above evaluations (2) and (3). Table 1 shows the results.

[Examples 2 to 4]
A retardation layer was prepared in the same manner as in Example 1 except that in the polarizer production process, the concentration of the boric acid aqueous solution used in the cross-linking treatment process was changed to obtain a polarizer having the boric acid content shown in Table 1. A polarizing plate was prepared. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Table 1 shows the results.

(Comparative example 1)
In the same manner as in Example 1, the structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/retardation layer (retardation layer/adhesive layer/another retardation layer) was prepared. A laminate having Then, the laminate was cut into a rectangle with a long side of 130 mm and a short side of 66 mm so that the long side direction of the retardation layer-attached polarizing plate and the slow axis of the retardation layer were perpendicular to each other.

Then, a pressure-sensitive adhesive layer (thickness 15 μm) is provided on the surface of another retardation layer, and a protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / retardation layer / adhesive layer / another A retardation layer-attached polarizing plate having a structure of retardation layer/adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 39.5 μm. The obtained polarizing plate with a retardation layer was subjected to the above evaluations (2) and (3). Table 1 shows the results.

(Comparative Examples 2 to 6)
A retardation layer was prepared in the same manner as in Comparative Example 1, except that the concentration of the boric acid aqueous solution used in the cross-linking treatment step was changed in the polarizer production step to obtain a polarizer having the boric acid content shown in Table 1. A polarizing plate was prepared. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Table 1 shows the results.

[evaluation]
As is clear from Table 1, the retardation layer-attached polarizing plates of Examples of the present invention exhibited suppressed retardation decrease even when subjected to weather resistance tests, and exhibited high light resistance and durability. It had.

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

REFERENCE SIGNS LIST 10 polarizing plate 11 polarizer 12 protective layer 20 retardation layer 30 adhesive layer 100 polarizing plate with retardation layer

Claims (9)

A rectangular polarizing plate with a retardation layer having a polarizing plate containing a polarizer and a retardation layer,
A polarizing plate with a retardation layer, wherein the long side direction of the polarizing plate with the retardation layer is parallel to the slow axis direction of the retardation layer. 2. The polarizing plate with a retardation layer according to claim 1, wherein the polarizer has a boric acid content of 25% by weight or less. 3. The retardation layer-attached polarizing plate according to claim 1, wherein the angle between the absorption axis of the polarizer and the long side direction of the retardation layer-attached polarizing plate is 35° to 55°. 4. The retardation layer-attached polarizing plate according to claim 1, wherein the retardation layer-attached polarizing plate has a length ratio of a long side to a short edge of 1.1 to 3.0. 5. The retardation layer-attached polarizing plate according to claim 1, wherein the retardation layer is an alignment fixed layer of a liquid crystal compound having a circularly polarizing function or an elliptically polarizing function. 6. The retardation layer-attached polarizing plate has a dimensional shrinkage rate of 0.076% or more in the short side direction when irradiated with xenon light for 100 hours under conditions of 55° C. and 50% RH. 4. The polarizing plate with a retardation layer according to . The polarizing plate with a retardation layer according to any one of claims 1 to 6, having a total thickness of 60 µm or less. An image display device comprising the retardation layer-attached polarizing plate according to any one of claims 1 to 7. 9. The image display device according to claim 8, which is an organic electroluminescence display device or an inorganic electroluminescence display device.

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