WO2023047748A1

WO2023047748A1 - Polarizing plate with phase difference layer, image display device using same, and method for evaluating polarizing plate with phase difference layer

Info

Publication number: WO2023047748A1
Application number: PCT/JP2022/025957
Authority: WO
Inventors: 洋毅千田; 大輔林; 克己塚本; 周作後藤
Original assignee: 日東電工株式会社
Priority date: 2021-09-27
Filing date: 2022-06-29
Publication date: 2023-03-30
Also published as: TW202313323A; JP2023047491A

Abstract

Provided is a polarizing plate with a phase difference layer having excellent high-temperature durability. A polarizing plate with a phase difference layer according to one embodiment of the present invention comprises a phase difference layer and a polarizing plate including a polarizer, wherein an angle formed between the absorption axis of the polarizer and the slow axis of the phase difference layer is 40-50°. The ratio x/y between a contraction dimension x in the slow axis direction of the phase difference layer after being left under a heating condition of 80°C for 500 hours for an evaluative square shape defined in the center of the polarizing plate with the phase difference layer, and the contraction dimension y in the fast axis direction of the phase difference layer for the same evaluative square shape, is 0.994 to 1.004.

Description

Polarizing plate with retardation layer, image display device using the same, and evaluation method for polarizing plate with retardation layer

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

In recent years, image display devices represented 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. As a thin retardation film, a retardation plate manufactured using a liquid crystal material is used. A thin retardation film is susceptible to dimensional shrinkage of the polarizing plate under heating conditions, and the retardation may change. As a result, the reflected hue may change.

Japanese Patent No. 3325560

The present invention has been made to solve the conventional problems described above, and its main purpose is to provide a polarizing plate with a retardation layer that is excellent in high-temperature durability.

The polarizing plate with a retardation layer of the embodiment of the present invention has a polarizing plate containing a polarizer and a retardation layer, and the angle formed by the absorption axis of the polarizer and the slow axis of the retardation layer is 40° to 50°. This polarizing plate with a retardation layer is a square for evaluation defined in the center of the polarizing plate with a retardation layer, and the retardation layer shrinks in the slow axis direction after being placed under heating conditions at 80 ° C. for 500 hours. The ratio x/y between the dimension x and the shrinkage dimension y in the fast axis direction of the retardation layer is 0.994 to 1.004.
In one embodiment, the retardation layer-attached polarizing plate has an aspect ratio of 0.15 to 3.0.
In one embodiment, the retardation layer is a fixed alignment layer of a liquid crystal compound.
In one embodiment, the in-plane retardation of the retardation layer is 100 nm<Re(550)<160 nm, and Re(450)/Re(550)<1 and Re(650)/Re (550)>1.
In one embodiment, the polarizer has a thickness of 7 μm or more.
In one embodiment, the boric acid content of the polarizer is 20% by weight 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 electroluminescent display device or an inorganic electroluminescent display device.
In still another aspect of the present invention, a method for evaluating a retardation layer-attached polarizing plate having a polarizing plate including a polarizer and a retardation layer is provided. This evaluation method is to define a square for evaluation in the center of the polarizing plate with a retardation layer, place the polarizing plate with a retardation layer in which the evaluation square is defined at 80 ° C. for 500 hours, and place the evaluation square Measuring the shrinkage dimension x in the slow axis direction of the retardation layer and the shrinkage dimension y in the fast axis direction of the retardation layer, and calculating the shrinkage dimension ratio x/y from the shrinkage dimension x and the shrinkage dimension y ,including.

According to the embodiment of the present invention, it is possible to provide a thin polarizing plate with a retardation layer that is excellent in high-temperature durability. According to the embodiment of the present invention, even when heated, a change in phase difference due to dimensional shrinkage is suppressed, and a change in reflection hue can also be suppressed. As a result, a polarizing plate with a retardation layer having excellent high-temperature durability and reflection hue can be provided.

1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention; FIG. FIG. 2 is a plan view of the retardation layer-attached polarizing plate before heating for explaining a method for measuring the shrinkage dimension ratio x/y in the embodiment of the present invention. 4 is a graph showing the relationship between the shrinkage dimension ratio x/y and the retardation change ΔRe of the retardation layer-attached polarizing plates of Examples and Comparative Examples.

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). In one embodiment, the retardation layer 20 is an alignment fixed layer of a liquid crystal compound (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 film is temporarily attached to the surface of the pressure-sensitive adhesive layer 30 until the polarizing plate is used. By temporarily attaching the release film, the pressure-sensitive adhesive layer can be appropriately protected.

In one embodiment, the angle between the absorption axis of the polarizer 11 and the slow axis of the retardation layer 20 is 40° to 50°, preferably 42° to 48°, more preferably about 45°. is. If the angle formed by the absorption axis of the polarizer 11 and the slow axis of the retardation layer 20 is within this range, a polarizing plate with a retardation layer having excellent antireflection properties can be obtained.

In one embodiment, a square for evaluation defined in the center of the polarizing plate with a retardation layer, the shrinkage dimension x in the slow axis direction of the retardation layer after being placed under heating conditions at 80 ° C. for 500 hours and The ratio of the retardation layer to the shrinkage dimension y in the fast axis direction (shrinkage dimension ratio) x/y is 0.994 to 1.004. The dimensional shrinkage of the central portion of the retardation layer-attached polarizing plate can be correlated with the retardation change (ΔRe) of the retardation layer-attached polarizing plate. By setting the shrinkage dimensional ratio x/y within the above range, the change in phase difference due to dimensional shrinkage is suppressed even when heated, and the change in reflection hue can also be suppressed. As a result, a polarizing plate with a retardation layer having excellent high-temperature durability and reflection hue can be provided. The shrinkage dimension ratio x/y is preferably 0.995 to 1.003, more preferably 0.996 to 1.002, still more preferably 0.997 to 1.001. The closer the shrinkage dimension ratio x/y is to 1, the better.

The retardation polarizing plate can be designed into any appropriate shape depending on the application. Typically, the retardation layer-attached polarizing plate is rectangular. Hereinafter, embodiments of the present invention will be described using a rectangular retardation layer-attached polarizing plate as an example. FIG. 2 is a plan view of a polarizing plate with a retardation layer before heating for explaining a method for measuring the shrinkage dimension ratio x/y in an embodiment of the present invention. In the illustrated example, in the polarizing plate 100 with retardation layers, the solid line direction corresponds to the slow axis direction of the retardation layer, and the broken line direction corresponds to the fast axis direction of the retardation layer. In the illustrated example, the retardation layer-equipped polarizing plate has the slow axis in the long side direction, but the slow axis may be in the short side direction. First, a square for evaluation is defined at the center O of the polarizing plate 100 with a retardation layer. The central portion O is a portion including the center of gravity of the polarizing plate with the retardation layer. In one embodiment, an evaluation square 200 is defined as a 1 cm square at center O. FIG. The evaluation square 200 is defined so that the center of gravity of the retardation layer-attached polarizing plate and the center of gravity of the evaluation square 200 correspond to each other. Any appropriate method can be used as the defining method. For example, it may be drawn directly on the retardation layer-attached polarizing plate, or any appropriate mark may be attached. Drawing can be done in any suitable way. For example, there are a method of scratching the outermost surface of the polarizing plate using any appropriate means such as a cutter and drawing, and a method of drawing on the outermost surface of the polarizing plate using a writing instrument such as an oil-based pen. . Preferably, a drawing method is used in which the outermost surface of the polarizing plate is scratched using any appropriate means such as a cutter. The size of the evaluation square can be set to any appropriate size according to the size of the retardation layer-attached polarizing plate. As described above, for example, a square with a side of 1 cm is adopted as the evaluation square. The retardation layer-attached polarizing plate in which the evaluation squares 200 were defined was placed in an environment of 80° C. for 500 hours. After heating, the length of the side parallel to the slow axis direction _{of the evaluation square 200 in the retardation layer-attached polarizing plate 100 returned to room temperature and the length of the side parallel to the fast axis direction x 2} _were measured. Measure. Next, dimensional shrinkage in _the slow _axis direction x (x ₂ /x ₁ ). Similarly, from the initial value y ₁ of the side length in the fast axis direction of the evaluation square 200 and the length y ₂ of the side in the slow axis direction after heating, the dimensional shrinkage y (y ₂ / y ₁ ) is calculated. The shrinkage dimensional ratio x/y is calculated from the calculated dimensional shrinkage x in the slow axis direction and dimensional shrinkage y in the fast axis direction.

The retardation change ΔRe at the central portion of the polarizing plate with a retardation layer is preferably −3 nm to 3 nm, more preferably −2.5 nm to 2.5 nm, still more preferably −2.3 nm to 2.3 nm. be. When the retardation change ΔRe of the central portion of the retardation layer-attached polarizing plate is within the above range, the retardation change due to dimensional shrinkage is suppressed even when heated, and the reflection hue change can also be suppressed. As a result, a polarizing plate with a retardation layer having excellent high-temperature durability and reflection hue can be provided. In this specification, the retardation change ΔRe at the center of the polarizing plate with the retardation layer is defined (for example, drawn) on the polarizing plate with the retardation layer. It refers to the difference between the phase difference value of the square for evaluation after being left at room temperature for 500 hours and then returning to room temperature.

In one embodiment, the retardation layer-attached polarizing plate is rectangular. In this embodiment, the aspect ratio (horizontal side length/vertical side length) of the retardation layer-attached polarizing plate can be set to any appropriate value depending on the application. The aspect ratio of the retardation layer-attached polarizing plate is preferably 0.15 to 3.0, more preferably 0.17 to 2.5, still more preferably 0.3 to 2.2. When the aspect ratio is within the above range, the change in phase difference due to dimensional shrinkage can be suppressed even when heated, and the change in reflection hue can also be suppressed. As a result, a polarizing plate with a retardation layer having excellent high-temperature durability and reflection hue can be provided. In one embodiment, it is preferable that the horizontal direction is a side corresponding to the slow axis direction of the retardation layer, and the vertical direction is a side corresponding to the fast axis direction of the retardation layer.

The retardation layer 20 is preferably a liquid crystal alignment fixed layer. The retardation layer, which is a liquid crystal alignment fixed layer, may undergo a large change in retardation due to dimensional shrinkage of the polarizing plate with the retardation layer. According to the embodiment of the present invention, even when the liquid crystal alignment fixed layer is used as the retardation layer, the retardation change due to dimensional shrinkage is suppressed, and the reflection hue change can also be suppressed. As a result, a polarizing plate with a retardation layer having excellent reflection hue can be provided. 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 further include a retardation layer (not shown) other than the retardation layer 20 . 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. Another retardation layer is an arbitrary layer provided as needed, and may be omitted.

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

The total thickness of the retardation layer-attached polarizing plate is preferably 50 μm to 120 μm, more preferably 50 μm to 110 μm, still more preferably 60 μm to 100 μm. A polarizing plate with a retardation layer having a certain thickness tends to be greatly affected by dimensional shrinkage due to heating. According to the embodiment of the present invention, even when the polarizing plate with a retardation layer having such a thickness is heated, the change in retardation due to dimensional shrinkage is suppressed, and the change in reflection hue is also suppressed. obtain. 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. It 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 does not include the thickness of the pressure-sensitive adhesive layer 30 and the release film that can be temporarily adhered to its surface).

The components of the retardation layer-equipped 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 7 μm or more, more preferably 7 μm to 15 μm, still more preferably 7 μm to 12 μm. When the thickness of the polarizer is large, the dimensional shrinkage rate tends to increase, and the change in the retardation of the retardation layer may become more pronounced. In the embodiment of the present invention, even when a polarizer having the above thickness is used, it is excellent in high-temperature durability, retardation change due to dimensional shrinkage is suppressed, and reflection hue change can also be suppressed. As a result, a polarizing plate with a retardation layer having excellent reflection hue can be provided.

The boric acid content of the polarizer is preferably 20 wt % or less, more preferably 5 wt % to 20 wt %, still more preferably 10 wt % to 18 wt %. If the boric acid content of the polarizer is within such a range, it is possible to provide a thin polarizing plate with a retardation layer having excellent high-temperature durability. If the boric acid content is less than 5% by weight, the polarizer may become polyene and the durability may decrease. According to the embodiment of the present invention, even when heated, a change in phase difference due to dimensional shrinkage is suppressed, and a change in reflection hue can also be suppressed. As a result, a polarizing plate with a retardation layer having excellent reflection hue can be provided. The boric acid content of the polarizer can be adjusted, for example, by adjusting the boric acid content in the aqueous solutions used in the following steps. 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 be manufactured by any appropriate method. For example, any appropriate resin film such as a polyvinyl alcohol (PVA) resin film is subjected to various treatments such as swelling treatment, stretching treatment, dyeing treatment with a dichroic substance such as iodine, cross-linking treatment, washing treatment, and drying treatment. It can be manufactured by applying.

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 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 resins. , 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.

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 The retardation layer 20 is typically provided to impart antireflection properties to the polarizing plate, and can function as a λ/4 plate when the retardation layer is a single layer. As described above, the retardation layer is preferably an alignment fixed layer of a liquid crystal compound. The in-plane retardation Re(550) of the retardation layer is preferably more than 100 nm and less than 160 nm, more preferably 110 nm to 155 nm, still more preferably 130 nm to less than 150 nm.

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. Further, in the liquid crystal alignment fixed layer, the retardation change due to the dimensional shrinkage of the retardation layer-attached polarizing plate in a high-temperature environment may become more remarkable. In the embodiment of the present invention, even when the retardation layer, which is a fixed alignment layer of a liquid crystal compound, is employed, it is possible to provide a polarizing plate with a retardation layer that is excellent in high-temperature durability.

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 less than 1, more preferably 0.8 or more and less than 1, and still more preferably 0.8 or more and 0.95 or less. . In addition, Re(550)/Re(650) of the retardation layer is preferably greater than 1, more preferably greater than 1 and 1.2 or less, still more preferably 1.01 to 1.15. With such a configuration, very excellent antireflection properties can be achieved.

As described above, the angle 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°, and more preferably about 45°. If the angle is in such a range, by using the retardation layer as a λ / 4 plate as described above, a retardation having very good circular polarization properties (as a result, very good antireflection properties) A layered polarizing plate can be obtained.

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 an alignment fixed 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.

The expression of liquid crystallinity 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 group 14 to group 16 nonmetallic atoms 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 straight 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 (I) 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 appropriate 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 orientation treatment can be adopted as the orientation 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.

　The alignment of the liquid crystal compound is performed by processing at a temperature that exhibits a liquid crystal phase 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 surface of the base material.

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 a refractive index characteristic of nz>nx=ny can be made of any appropriate 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. Applications of Retardation Layer-attached Polarizing Plate The retardation layer-attached polarizing plate of the embodiment of the present invention can be used for any appropriate application. In one embodiment, the retardation layer-attached polarizing plate can be suitably used for an image display device. Preferably, the retardation layer-attached polarizing plate can be suitably used for an organic electroluminescence device and an inorganic electroluminescence device.

G. 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. 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 E 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).

H. Evaluation Method One embodiment of the present invention provides a method for evaluating a polarizing plate with a retardation layer. A method for evaluating a polarizing plate with a retardation layer according to an embodiment of the present invention includes: defining a square for evaluation in the center of the polarizing plate with a retardation layer; ° C. for 500 hours, measuring the shrinkage dimension x in the slow axis direction of the retardation layer for evaluation and the shrinkage dimension y in the fast axis direction of the retardation layer for evaluation, and shrinkage dimension x and shrinkage dimension y calculating the shrinkage dimension ratio x/y from According to the evaluation method according to the embodiment of the present invention, it is possible to evaluate the high-temperature durability of the retardation layer-attached polarizing plate, that is, the degree of change in retardation when placed in a high-temperature environment.

The retardation polarizing plate can be designed into any appropriate shape depending on the application. Typically, the retardation layer-attached polarizing plate is rectangular. Hereinafter, the evaluation method of the embodiment of the present invention will be described by taking a rectangular polarizing plate with a retardation layer as an example. First, an evaluation square is defined at the center of the retardation layer-attached polarizing plate to be evaluated. The central part is as described above. For example, a square (for example, a square with a side of 1 cm) is defined by any appropriate method so that the center of gravity of the retardation layer-attached polarizing plate and the center of gravity of the evaluation square correspond to each other. Any appropriate method can be used as the defining method. For example, it may be drawn on the polarizing plate with a retardation layer, or a mark may be attached. The drawing method includes, for example, a method of scratching the outermost surface of the polarizing plate using any appropriate means such as a cutter, and drawing on the outermost surface of the polarizing plate using a writing instrument such as an oil-based pen. methods and the like. Preferably, a drawing method is used in which the outermost surface of the polarizing plate is scratched using any appropriate means such as a cutter.

Next, the polarizing plate with a retardation layer having the defined evaluation squares is placed in an environment of 80° C. for 500 hours. After heating, in the polarizing plate with a retardation layer returned to room temperature, the length x ₂ of the side parallel to the slow axis direction and the length y ₂ of the side parallel to the fast axis direction of the square for evaluation are measured. . Next, dimensional _shrinkage _{in the slow axis direction x (x 2} _/ x ₁ ) is calculated. _Similarly _, the dimensional contraction y ( _y ₁ ) is calculated. The shrinkage dimensional ratio x/y is calculated from the calculated dimensional shrinkage x in the slow axis direction and dimensional shrinkage y in the fast axis direction.

The closer the calculated shrinkage dimension ratio x/y is to 1, the better the polarizing plate with a retardation layer is in high temperature durability, indicating that the retardation change is suppressed even when placed in a high temperature environment. The shrinkage dimension ratio x/y is preferably 0.995 to 1.003, more preferably 0.996 to 1.002, still more preferably 0.997 to 1.001.

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 A 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) Shrinkage dimension ratio x/y
By using a cutter to scratch the outermost surface of the polarizing plate with a retardation layer obtained in Examples and Comparative Examples, the center of gravity of the polarizing plate with a retardation layer corresponds to the center of gravity. A 1 cm square (evaluation square) was drawn at the position. Then, the pressure-sensitive adhesive layer of the retardation layer-attached polarizing plate was laminated on a glass plate (80 mm×150 mm) having a thickness of 0.5 mm. After that, the polarizing plate with a retardation layer attached to the glass plate was placed under conditions of 80° C. for 500 hours. Then, using an XY length measuring machine (manufactured by Mitutoyo, product name: QUICK VISION QVA1517-PRO), the shrinkage dimension x ₂ of the side parallel to the slow axis direction of the evaluation square retardation layer and the fast axis direction and the shrinkage dimension y ₂ of the side parallel to was measured respectively. Next, the shrinkage dimension x (x ₂ /1 (cm)) in the slow axis direction and the shrinkage dimension y (y ₂ /1 (cm)) in the fast axis direction were calculated. The shrinkage dimension ratio x/y was calculated from the shrinkage dimension x in the slow axis direction and the shrinkage dimension y in the fast axis direction.

(3) ΔRe
By using a cutter to scratch the outermost surface of the polarizing plate with a retardation layer obtained in Examples and Comparative Examples, the center of gravity of the polarizing plate with a retardation layer corresponds to the center of gravity. A 1 cm square (evaluation square) was drawn at the position. The initial in-plane retardation Re ₀ of the in-plane retardation Re of the evaluation square portion was measured using a retardation film/optical material inspection device (manufactured by Otsuka Electronics Co., Ltd., trade name “RETS”). Then, the pressure-sensitive adhesive layer of the retardation layer-attached polarizing plate was laminated on a glass plate (80 mm×150 mm) having a thickness of 0.5 mm. After that, the polarizing plate with a retardation layer attached to the glass plate was placed under conditions of 80° C. for 500 hours. Thereafter, the in-plane retardation Re ₅₀₀ after heating of the square portion for evaluation was similarly measured. ΔRe (nm) was calculated from the initial in-plane retardation Re ₀ and the in-plane retardation Re ₅₀₀ after heating.

(4) Δa ^* b ^*
By using a cutter to scratch the outermost surface of the polarizing plate with a retardation layer obtained in Examples and Comparative Examples, the center of gravity of the polarizing plate with a retardation layer corresponds to the center of gravity. A 1 cm square (evaluation square) was drawn at the position. For the evaluation square portion, the a value and b value were measured using a UV-visible spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, product name: V-7100). This was taken as the _a0 and _b0 values. Then, the pressure-sensitive adhesive layer of the retardation layer-attached polarizing plate was laminated on a glass plate (80 mm×150 mm) having a thickness of 0.5 mm. After that, the polarizing plate with a retardation layer attached to the glass plate was placed under conditions of 80° C. for 500 hours. The a ₅₀₀ value and b ₅₀₀ value after being placed at 80° C. for 500 hours were similarly determined. From these values, the hue change amount Δab was obtained using the following formula.
Δa ^* b ^* ={(a ₅₀₀ −a ₀ ) ² +(b ₅₀₀ −b ₀ ) ² } ^1/2

[Production Example 1: Production of polarizing plate with retardation layer]
1. Preparation of polarizer A long roll of polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name “PE3000”) with a thickness of 30 μm was uniaxially stretched in the longitudinal direction by a roll stretching machine so that it was 5.9 times longer in the longitudinal direction. A polarizer having a thickness of 12 μm was produced by simultaneously performing swelling, dyeing, cross-linking, and washing treatments while stretching, and finally performing a drying treatment.
Specifically, in the swelling treatment, the film was stretched 2.2 times while being treated with pure water at 20°C. Next, the dyeing treatment is performed in an aqueous solution at 30° C. in which the weight ratio of iodine and potassium iodide is 1:7 and the iodine concentration is adjusted so that the single transmittance of the resulting polarizer is 45.0%. while stretching to 1.4 times. Furthermore, a two-step cross-linking treatment was adopted for the cross-linking treatment, and in the first-step cross-linking treatment, the film was stretched 1.2 times while being treated in an aqueous solution of boric acid and potassium iodide at 40°C. The boric acid content of the aqueous solution for the first-stage cross-linking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight. In the second-stage cross-linking treatment, the film was stretched 1.6 times while being treated in an aqueous solution of boric acid and potassium iodide at 65°C. The boric acid content of the aqueous solution for the second-stage cross-linking treatment was 3.7% by weight, and the potassium iodide content was 5.0% by weight. Further, the cleaning treatment was performed with an aqueous solution of potassium iodide at 20°C. The potassium iodide content of the aqueous solution for the cleaning treatment was 3.1% by weight. Finally, the drying treatment was performed at 70° C. for 5 minutes to obtain a polarizer.

2. Preparation of Polarizing Plate An HC-COP film as a protective layer was attached 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.

3. Preparation of First 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) are After adding to non (CPN) 400 parts by weight, it was dissolved by heating to 60° C. and stirring. 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 resulting coating film to room temperature, using a high-pressure mercury lamp, ultraviolet light is irradiated for 30 seconds at an intensity of 30 mW/cm ² to obtain a first retardation layer that is an aligned solid layer of a liquid crystal compound. rice field. The in-plane retardation Re(550) of the first retardation layer was 130 nm. In addition, the Re(450)/Re(550) of the first retardation layer was 0.851, indicating reverse dispersion wavelength characteristics. The first retardation layer can function as a λ/4 plate.

4. Preparation of the second retardation layer Side chain type liquid crystal represented by the following chemical formula (numbers 65 and 35 in the formula indicate mol% of the monomer unit and are conveniently represented by block polymer: weight average molecular weight 5000) Polymer 20 parts by weight, polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242) 80 parts by weight and photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) 5 parts by weight of cyclopentanone A liquid crystal coating liquid was prepared by dissolving in 200 parts by weight. 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.

Next, a UV adhesive was applied to the surface of the first retardation layer and the surface of the second retardation layer, and after they were bonded together, they were irradiated with UV light to cure and adhere. After that, the substrate of the first retardation layer was peeled off, and after plasma treatment, an undercoat was applied and dried, and then an acrylic pressure-sensitive adhesive (thickness: 5 μm) was applied and dried. Next, the acrylic pressure-sensitive adhesive surface of these laminates and the TAC surface of the protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/protective layer (TAC) are laminated together. The substrate on the surface of the retardation layer of 2 is peeled off, an adhesive layer (thickness 26 μm) is provided, and a protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/protective layer (TAC)/ A polarizing plate with a retardation layer having a structure of adhesive layer//first retardation layer/adhesive layer/second retardation layer)/adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 100 μm.

[Example 1-1]
The retardation layer-attached polarizing plate obtained in Production Example 1 was cut using a film cutting machine so as to have a length of 6.5 cm and a width of 13 cm (aspect ratio: 2), and subjected to the evaluation of (2) to (4). bottom. Table 1 shows the results.

[Example 1-2]
The retardation layer-attached polarizing plate obtained in Production Example 1 was cut using a film cutting machine so as to have a length of 7.8 cm and a width of 11 cm (aspect ratio: 1.4), and the evaluation of (2) to (4). served to Table 1 shows the results.

[Example 1-3]
The retardation layer-attached polarizing plate obtained in Production Example 1 was cut using a film cutting machine so as to have a length of 9.3 cm and a width of 9.3 cm (aspect ratio: 1), and the evaluation of (2) to (4). served to Table 1 shows the results.

[Example 1-4]
The retardation layer-attached polarizing plate obtained in Production Example 1 was cut using a film cutting machine so as to have a length of 12 cm and a width of 8 cm (aspect ratio: 0.67), and subjected to the evaluation of (2) to (4). bottom. Table 1 shows the results.

[Example 1-5]
The retardation layer-attached polarizing plate obtained in Production Example 1 was cut using a film cutting machine so as to have a length of 13 cm and a width of 6.5 cm (aspect ratio: 0.5), and the evaluation of (2) to (4). served to Table 1 shows the results.

[Example 1-6]
The retardation layer-attached polarizing plate obtained in Production Example 1 was cut using a film cutting machine so as to have a length of 16 cm and a width of 6 cm (aspect ratio: 0.38), and subjected to the evaluation of (2) to (4). bottom. Table 1 shows the results.

[Example 1-7]
The retardation layer-attached polarizing plate obtained in Production Example 1 was cut using a film cutting machine so as to have a length of 24 cm and a width of 4 cm (aspect ratio: 0.17), and subjected to the evaluation of (2) to (4). bottom. Table 1 shows the results.

[Example 2]
Polarized light with a retardation layer 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 with a boric acid content of 17% by weight. A plate was made. The obtained polarizing plate with a retardation layer was cut using a film cutting machine so as to have a length of 6.5 cm and a width of 13 cm (aspect ratio: 2). The cut polarizing plate with a retardation layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Comparative example 1)
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 prepared in the same manner as in Example 1 except that the obtained polarizing plate with a retardation layer was cut to have a length of 4 cm and a width of 24 cm (aspect ratio: 6). was used for evaluation. Table 1 shows the results.

(Comparative example 2)
A retardation layer was prepared in the same manner as in Example 1-1 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 a boric acid content of 22% by weight. 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 the examples of the present invention were excellent in high-temperature durability. FIG. 3 shows the distribution of the shrinkage dimension ratio x/y and ΔRe of the retardation layer-attached polarizing plates obtained in Examples and Comparative Examples. As can be seen from the graph in FIG. 3, there was a correlation between the shrinkage dimension ratio x/y and ΔRe. By measuring the shrinkage dimension ratio x/y, it was possible to evaluate the degree of change in the retardation of the retardation layer-attached polarizing plate.

The polarizing plate with a retardation layer of the present invention is suitably used 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

A polarizing plate including a polarizer and a retardation layer,
A polarizing plate with a retardation layer, wherein the angle formed by the absorption axis of the polarizer and the slow axis of the retardation layer is 40° to 50°,
The shrinkage dimension x in the slow axis direction of the retardation layer after placing the square for evaluation defined in the center of the polarizing plate with the retardation layer under heating conditions at 80 ° C. for 500 hours and the progress of the retardation layer A polarizing plate with a retardation layer, wherein the ratio x/y to the shrinkage dimension y in the phase axis direction is 0.994 to 1.004.
The polarizing plate with a retardation layer according to claim 1, which has an aspect ratio of 0.15 to 3.0.
The polarizing plate with a retardation layer according to claim 1 or 2, wherein the retardation layer is an alignment fixed layer of a liquid crystal compound.
The in-plane retardation of the retardation layer is 100 nm<Re(550)<160 nm, and
4. The retardation layer-attached polarizing plate according to claim 1, which satisfies Re(450)/Re(550)<1 and Re(650)/Re(550)>1.
The polarizing plate with a retardation layer according to any one of claims 1 to 4, wherein the polarizer has a thickness of 7 µm or more.
The polarizing plate with a retardation layer according to any one of claims 1 to 5, wherein the polarizer has a boric acid content of 20% by weight or less.
An image display device comprising the retardation layer-attached polarizing plate according to any one of claims 1 to 6.
The image display device according to claim 7, which is an organic electroluminescence display device or an inorganic electroluminescence display device.
A method for evaluating a polarizing plate with a retardation layer comprising a polarizing plate containing a polarizer and a retardation layer,
Prescribing an evaluation square in the center of the retardation layer-attached polarizing plate;
placing the polarizing plate with a retardation layer in which the evaluation squares are defined at 80° C. for 500 hours;
measuring the shrinkage dimension x in the slow axis direction of the square retardation layer for evaluation and the shrinkage dimension y in the fast axis direction of the retardation layer;
A method for evaluating a polarizing plate with a retardation layer, comprising calculating a shrinkage dimension ratio x/y from the shrinkage dimension x and the shrinkage dimension y.