Polarizing plate with retardation layer and image display device including the polarizing plate with retardation layer

Abstract

To provide a polarizer with a phase difference layer with an excellent durability to high temperatures.SOLUTION: A polarizer 100 with a phase difference layer includes a polarizer 10 including a polarizer 11 with a thickness of at least 7 μm; a first phase difference layer 20 as an orientation solidification layer of a liquid crystal compound; and a second phase difference layer 30 made of a resin film containing a polymer with a negative double refraction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate with a retardation layer and an image display device including the polarizing plate with a retardation layer. [Background technology]

[0002] In recent years, image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), have rapidly become widespread. Image display devices typically use polarizing plates and retardation plates. In practice, retardation layer-attached polarizing plates, which integrate a polarizing plate and a retardation plate, are widely used (e.g., Patent Document 1). As demand for thinner image display devices increases, so does the demand for thinner retardation layer-attached polarizing plates. To achieve thinner retardation layer-attached polarizing plates, thinner retardation plates have been developed, and retardation plates made using liquid crystal-based materials are being used. Thinner retardation plates are prone to significant dimensional shrinkage under high-temperature conditions, which can cause changes in retardation. Furthermore, retardation layers formed using liquid crystal-based materials are more susceptible to the effects of dimensional shrinkage, which can result in greater changes in the reflection hue. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3325560 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide a polarizing plate with a retardation layer in which in-plane unevenness of reflection hue is suppressed and which has excellent high-temperature durability. [Means for solving the problem]

[0005] A polarizing plate with a retardation layer according to an embodiment of the present invention includes a polarizing plate including a polarizer having a thickness of 7 μm or more, a first retardation layer which is an oriented and solidified layer of a liquid crystal compound, and a second retardation layer which is composed of a resin film including a polymer exhibiting negative birefringence. In one embodiment, the second retardation layer is adjacent to the first retardation layer. In one embodiment, the second retardation layer is a positive C plate. In one embodiment, the second retardation layer has a thickness of 1 μm to 30 μm. In one embodiment, the polymer exhibiting negative birefringence is at least one selected from the group consisting of acrylic resins, styrene resins, and maleimide resins. In one embodiment, the in-plane retardation of the first retardation layer is 100 nm <Re(550)<160nmであり、かつ、Re(450) / Re(550)<1、および、Re(650) / Re(550)> Satisfies 1. In one embodiment, the angle formed between the slow axis of the first retardation layer and the absorption axis of the polarizer is 40° to 50°. In one embodiment, the first phase layer has a laminated structure of a liquid crystal compound alignment layer A and a liquid crystal compound alignment layer B, in which the alignment layer A functions as a λ / 2 plate and the alignment layer B functions as a λ / 4 plate. In one embodiment, the angle formed between the slow axis of the alignment and solidification layer A of the liquid crystal compound and the absorption axis of the polarizer is 70° to 80°, and the angle formed between the slow axis of the alignment and solidification layer B of the liquid crystal compound and the absorption axis of the polarizer is 10° to 20°. In another aspect of the present invention, there is provided an image display device, which includes the above-mentioned retardation layer-attached polarizing plate. [Effects of the Invention]

[0006] According to an embodiment of the present invention, a polarizing plate with a retardation layer can be provided in which in-plane unevenness in reflection hue is suppressed and which has excellent high-temperature durability. According to an embodiment of the present invention, even in a polarizing plate with a retardation layer that includes a retardation layer that is a liquid crystal alignment solidified layer, change in the retardation of the polarizing plate in a high-temperature environment is suppressed. Therefore, change in reflection hue can also be suppressed. As a result, a polarizing plate with a retardation layer can be provided in which in-plane unevenness in reflection hue is suppressed and which has excellent high-temperature durability. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to another embodiment of the present invention.

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] (Definition of terms and symbols) The definitions of terms and symbols used in this specification 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 greatest (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light of wavelength 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d, where d (nm) is the thickness of the layer (film). (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) is calculated 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 calculated by Nz=Rth / Re. (5)Angle When angles are referred to herein, the angles include both clockwise and counterclockwise angles relative to a reference direction, so for example, "45°" means ±45°.

[0010] A. Overall structure of polarizing plate with retardation layer FIG. 1 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to one embodiment of the present invention. The retardation layer-attached polarizing plate 100 shown in the figure has a polarizing plate 10, a first retardation layer 20, and a second retardation layer 30, in this order from the viewing side. The polarizing plate 10 typically includes a polarizer 11 and protective layers 12 and 13 disposed on both sides of the polarizer 11. The protective layer 13 may be omitted. The components constituting the retardation layer-attached polarizing plate may be laminated via any appropriate adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and a pressure-sensitive adhesive layer. The first retardation layer 20 is a layer in which a liquid crystal compound is aligned and solidified (hereinafter, sometimes simply referred to as a liquid crystal alignment and solidified layer). The second retardation layer 30 is composed of a resin film containing a polymer exhibiting negative birefringence. In the illustrated example, the first retardation layer 20 is a single layer. By including the first retardation layer 20, which is a liquid crystal alignment solidified layer, and the second retardation layer 30, which is composed of a resin film containing a polymer exhibiting negative birefringence, a retardation-layered polarizing plate with reduced in-plane unevenness in reflection hue and excellent high-temperature durability can be provided. The first retardation layer, which is a liquid crystal alignment solidified layer, is susceptible to the shrinkage of the polarizing plate in high-temperature environments, which can cause changes in retardation. As a result, the reflection hue of the retardation-layered polarizing plate can change, resulting in in-plane unevenness in reflection hue. By including the second retardation layer composed of a resin film containing a polymer exhibiting negative birefringence, the effect of dimensional shrinkage of the polarizing plate on the first retardation layer can be alleviated. As a result, changes in the retardation of the first retardation layer can be suppressed. Furthermore, by being composed of a resin film containing a polymer exhibiting negative birefringence, changes in the retardation of the second retardation layer due to dimensional shrinkage of the polarizing plate in high-temperature environments can be reduced. Therefore, changes in the retardation of the retardation-layered polarizing plate in high-temperature environments can be suppressed, and in-plane unevenness in reflection hue can be further suppressed. Preferably, the first retardation layer 20 and the second retardation layer 30 are adjacent to each other. By having the first retardation layer, which is a liquid crystal alignment solidified layer, and the second retardation layer, which is made of a resin film, adjacent to each other, in-plane unevenness in the reflection hue is further suppressed, and a retardation layer-attached polarizing plate having excellent high-temperature durability can be provided. In this specification, adjacent includes not only being directly adjacent to each other but also being adjacent to each other via an optional adhesive layer.In this specification, the term "liquid crystal alignment solidified layer" refers to a layer in which liquid crystal compounds are aligned in a predetermined direction within the layer and the alignment state is fixed. Note that the term "alignment solidified layer" is a concept that encompasses a solidified alignment layer obtained by solidifying a liquid crystal monomer, as described below.

[0011] In the illustrated example, the second retardation layer 30 is laminated on the surface of the first retardation layer 20 that is not in contact with the polarizing plate 10, but the second retardation layer 30 may be disposed between the polarizing plate 10 and the first retardation layer 20.

[0012] FIG. 2 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to another embodiment of the present invention. The retardation layer-attached polarizing plate 101 shown in the figure includes, in this order from the viewing side, a polarizing plate 10, a first retardation layer 20 that is a liquid crystal alignment solidified layer, and a second retardation layer 30 composed of a resin film containing a polymer exhibiting negative birefringence. In the illustrated example, the first retardation layer 20 has a laminated structure of a liquid crystal alignment solidified layer A21 and a liquid crystal alignment solidified layer B22. Even when a liquid crystal alignment solidified layer having a laminated structure is used as the first retardation layer 20, in-plane unevenness in the reflection hue can be suppressed, and a retardation layer-attached polarizing plate with excellent high-temperature durability can be provided. In the illustrated example, the liquid crystal alignment solidified layer B22 and the second retardation layer 30 are arranged adjacent to each other, but the second retardation layer 30 may also be arranged between the polarizing plate 10 and the liquid crystal alignment solidified layer A21.

[0013] In one embodiment, the retardation layer-attached polarizing plates 100, 101 have a pressure-sensitive adhesive layer on the outermost layer (for example, on the surface of the second retardation layer 30 in the illustrated example on which the first retardation layer 20 is not laminated), and can be attached to an image display device (essentially, an image display cell). In practice, it is preferable that a release liner be temporarily attached to the surface of the pressure-sensitive adhesive layer until the polarizing plate is used. By temporarily attaching the release liner, the pressure-sensitive adhesive layer can be appropriately protected.

[0014] The retardation layer-attached polarizing plate may further include a retardation layer (not shown) other than the first retardation layer 20 and the second retardation layer 30. The other retardation layer is an optional layer provided as needed and may be omitted. The optical properties (e.g., refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the other retardation layer may be appropriately set depending on the purpose.

[0015] In the polarizing plate with a retardation layer, the ratio of the thickness of the polarizer to the thickness of the first retardation layer (thickness of polarizer / thickness of first retardation layer) is, for example, 0.5 to 7, preferably 1 to 6, and more preferably 2 to 5. According to the embodiment of the present invention, even in such a polarizing plate with a retardation layer, change in retardation due to dimensional shrinkage in a high-temperature environment can be suppressed, and change in reflected hue can also be suppressed.

[0016] The total thickness of the retardation layer-attached polarizing plate is preferably 40 μm to 120 μm, more preferably 40 μm to 110 μm, and even more preferably 50 μm to 100 μm. Retardation layer-attached polarizing plates containing polarizing plates with a certain thickness can have such a thickness. Such retardation layer-attached polarizing plates tend to be significantly affected by dimensional shrinkage of the polarizing plate in a high-temperature environment. According to an embodiment of the present invention, even a retardation layer-attached polarizing plate having the above thickness can suppress changes in retardation due to dimensional shrinkage in a high-temperature environment, and can also suppress changes in reflection hue. The total thickness of the retardation layer-attached polarizing plate refers to the sum of the thicknesses of the polarizing plate, the retardation layer (if another retardation layer is present, the retardation layer and the other retardation layer), and the adhesive layer for laminating them (i.e., the total thickness of the retardation layer-attached polarizing plate does not include the thickness of the pressure-sensitive adhesive layer provided as the outermost layer and the thickness of a release liner that may be temporarily attached to the surface).

[0017] The components of the retardation layer-attached polarizing plate will be described in more detail below.

[0018] B. Polarizing plate B-1.Polarizer The polarizer is typically made of a polyvinyl alcohol (PVA) resin film containing a dichroic material. The thickness of the polarizer is, as described above, 7 μm or more, for example, 8 μm or more, or for example, 10 μm or more, or for example, 12 μm or more, or for example, 15 μm or more. When the polarizer is thick, the dimensional shrinkage of the retardation layer-attached polarizing plate tends to increase, and the retardation change may become more pronounced. In the embodiment of the present invention, even when a polarizer having the above thickness is used, the high-temperature durability is excellent, and the retardation change due to dimensional shrinkage can be suppressed. As a result, the in-plane reflection hue unevenness of the retardation layer-attached polarizing plate can be suppressed. The thickness of the polarizer is, for example, 30 μm or less.

[0019] The boric acid content of the polarizer is preferably 20% by weight or less, more preferably 5 to 20% by weight, and even more preferably 10 to 18% by weight. When the boric acid content of the polarizer is within this range, a polarizing plate with a retardation layer having excellent high-temperature durability can be provided. If the boric acid content is less than 5% by weight, the polarizer may undergo polyenization, resulting in a decrease in durability. According to an embodiment of the present invention, even when placed in a high-temperature environment, changes in retardation due to dimensional shrinkage of the polarizing plate can be suppressed, and changes 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 solution used in each of the following steps. The boric acid content can be calculated, for example, from the neutralization method using the following formula as the amount of boric acid contained in the polarizer per unit weight.

number

[0020] The iodine content of the polarizer is preferably 2% by weight or more, and more preferably 2% by weight to 10% by weight. When the iodine content of the polarizer is in this range, a synergistic effect with the boric acid content can be achieved, which favorably maintains ease of curl control during lamination, favorably suppresses curl during heating, and improves appearance durability during heating. In this specification, the "iodine content" refers to the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, iodine in the polarizer is converted into iodine ions (I - ), molecular iodine (I2), polyiodine ion (I3 - , I5 - ), and the iodine content in this specification refers to the amount of iodine including all of these forms. The iodine content can be calculated, for example, by the calibration curve method of X-ray fluorescence analysis. Note that polyiodine ions exist in the polarizer in the form of a PVA-iodine complex. The formation of such a complex can cause absorption dichroism in the wavelength range of visible light. Specifically, a complex of PVA and triiodide ion (PVA·I3 - ) has an absorption peak around 470 nm, and the complex of PVA and pentaiodide ion (PVA·I5 - ) has an absorption peak around 600 nm. As a result, polyiodide ions can absorb light in a wide range of visible light depending on their form. On the other hand, iodide ions (I - ) has an absorption peak around 230 nm and does not substantially contribute to the absorption of visible light. Therefore, polyiodide ions present in a complex state with PVA may be primarily responsible for the absorption performance of the polarizer.

[0021] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The polarizer's single transmittance Ts is preferably 40% to 48%, more preferably 41% to 46%. The polarizer's degree of polarization P is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more. The single transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and corrected for luminosity. The degree of polarization is typically calculated by the following formula based on the parallel transmittance Tp and crossed transmittance Tc measured using an ultraviolet-visible spectrophotometer and corrected for luminosity. Degree of polarization (%)={(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100

[0022] The polarizer can be produced by any appropriate method, for example, by subjecting any appropriate resin film such as a polyvinyl alcohol (PVA)-based resin film to various treatments such as swelling treatment, stretching treatment, dyeing treatment with a dichroic substance such as iodine, crosslinking treatment, washing treatment, and drying treatment.

[0023] B-2.Protective layer The protective layers 12 and 13 are formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that can be the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polynorbornenes, polyolefins, (meth)acrylics, and acetates. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylics, urethanes, (meth)acrylic urethanes, epoxy resins, and silicones. Other examples include glassy polymers such as siloxane polymers. The polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in its side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups in its side chains, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer.The polymer film can be, for example, an extrusion molded product of the above resin composition.

[0024] The polarizing plate with a retardation layer is typically placed on the viewing side of the image display device, and the protective layer 12 is typically placed on the viewing side. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coating treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment, as needed.

[0025] The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm. When a surface treatment is applied, the thickness of the outer protective layer (protective layer 12) includes the thickness of the surface treatment layer.

[0026] C. First retardation layer The first retardation layer 20 is a layer of oriented and solidified liquid crystal compounds. By using a liquid crystal compound, it is possible to achieve an in-plane retardation equivalent to that of a resin film with a thickness significantly thinner than that of a resin film. Furthermore, in a liquid crystal oriented and solidified layer, the retardation change due to dimensional shrinkage of the retardation layer-attached polarizing plate in a high-temperature environment may become more pronounced. In an embodiment of the present invention, even when a retardation layer that is a layer of oriented and solidified liquid crystal compounds is used, a retardation layer-attached polarizing plate with excellent high-temperature durability can be provided. The first retardation layer may be a single layer or a laminate of two or more layers. The first retardation layer is typically provided to impart anti-reflection properties to the polarizing plate.

[0027] C-1. First retardation layer as a single layer When the first retardation layer 20 is a single layer, the single first retardation layer can function as a λ / 4 plate. The in-plane retardation Re(550) of the first retardation layer is preferably more than 100 nm and less than 160 nm, more preferably 110 nm to 155 nm, and even more preferably 130 nm to less than 150 nm.

[0028] The Nz coefficient of the first retardation layer, which is a single layer, is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3. By satisfying such a relationship, when the obtained retardation layer-attached polarizing plate is used in an image display device, an extremely excellent reflection hue can be achieved.

[0029] The thickness of the first retardation layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 7 μm, and further preferably 1 μm to 5 μm.

[0030] The first retardation layer preferably exhibits inverse dispersion wavelength characteristics. In this case, Re(550) / Re(650) is preferably greater than 1, more preferably greater than 1 but not greater than 1.2, and even more preferably 1.01 to 1.15. Furthermore, Re(450) / Re(550) of the first retardation layer is preferably less than 1, more preferably less than 0.95, and even more preferably less than 0.90. Re(450) / Re(550) is, for example, 0.8 or greater. With such a configuration, extremely excellent antireflection properties can be achieved.

[0031] The angle between the slow axis of the first retardation layer 20 and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. If the angle is in this range, by using a λ / 4 plate as the retardation layer as described above, a polarizing plate with a retardation layer having very good circular polarization properties (as a result, very good antireflection properties) can be obtained.

[0032] As described above, the first retardation layer 20 is a layer of a liquid crystal compound that has been solidified and aligned. By using a liquid crystal compound, the difference between nx and ny of the resulting retardation layer can be significantly increased compared to non-liquid crystal materials, and the thickness of the retardation layer required to obtain a desired in-plane retardation can be significantly reduced. As a result, the retardation layer-attached polarizing plate can be made even thinner.

[0033] The retardation layer, which is an alignment and solidification layer of a liquid crystal compound, can be formed using a composition containing a polymerizable liquid crystal compound. In this specification, the polymerizable liquid crystal compound contained in the composition refers to a compound having a polymerizable group and having liquid crystal properties. The polymerizable group refers to a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical or acid generated from a photopolymerization initiator.

[0034] The liquid crystallinity may be thermotropic or lyotropic. The liquid crystal phase may be nematic or smectic. From the viewpoint of ease of production, the liquid crystallinity is preferably thermotropic nematic.

[0035] In one embodiment, the retardation layer, which is a single 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)

[0036] L 1 and L 2 each independently represents a monovalent organic group; L 1 and L 2 At least one of L represents a polymerizable group. The monovalent organic group may include any suitable group. 1 and L 2 The polymerizable group represented by at least one of the above may be a radically polymerizable group (a group 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. From the viewpoint of high polymerization rate and improved productivity, an acryloyl group is preferred. A methacryloyl group can also be used as a polymerizable group for a highly birefringent liquid crystal.

[0037] SP 1 and SP 2each independently represents a single bond, a linear or branched alkylene group, or a divalent linking group in which one or more -CH2- groups constituting a linear or branched alkylene group having 1 to 14 carbon atoms have been substituted with -O-. Preferred examples of the linear or branched alkylene group having 1 to 14 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group.

[0038] A 1 and A 2 A each independently represents an alicyclic hydrocarbon group or an aromatic ring substituent. 1 and A 2 is preferably an aromatic ring substituent having 6 or more carbon atoms or a cycloalkylene ring having 6 or more carbon atoms.

[0039] D 1 , D 2 , D 3 and D 4 Each independently represents a single bond or a divalent linking group. 1 , D 2 , D 3 and D 4 represents 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 -CR2 R 3 -, or -CO-NR 1 - represents the D 1 , D 2 , D 3 and D 4 At least one of the groups represents -O-CO-. 3 is preferably —O—CO—, and D 3 and D 4 is more preferably -O-CO-. 1 and D 2 is preferably a single bond. 1 , R 2 , R 3 and R 4 each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms.

[0040] G 1 and G 2 Each of G independently represents a single bond or an alicyclic hydrocarbon group. 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 of the -CH2- groups constituting the alicyclic hydrocarbon group may be substituted with -O-, -S-, or -NH-. G 1 and G 2 preferably represents a single bond.

[0041] Ar represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar represents, for example, an aromatic ring selected from the group consisting of groups represented by the following formulae (Ar-1) to (Ar-6). In the following formulae (Ar-1) to (Ar-6), *1 represents D 1 *2 indicates the bond position with D 2 represents the bonding position with [ka]

[0042] In formula (Ar-1), Q 1 represents N or CH, and Q 2is -S-, -O-, or -N(R 5 )-. R 5 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0043] In formulas (Ar-1) to (Ar-6), Z 1 , Z 2 and Z 3 are each independently a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitro group, or -NR 6 R 7 , or -SR 8 Represents R 6 ~R 8 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; Z 1 and Z 2 may be bonded to each other to form a ring. The ring may be an alicyclic, heterocyclic, or aromatic ring, and is preferably an aromatic ring. The ring formed may be substituted with a substituent.

[0044] In formulas (Ar-2) and (Ar-3), A 3 and A 4 are each independently -O-, -N(R 9 represents a group selected from the group consisting of -, -S-, and -CO-; 9 represents a hydrogen atom or a substituent. 9 The substituent represented by is, for example, Y in the above formula (Ar-1). 1 The substituents are the same as those that may be contained in the group.

[0045] In formula (Ar-2), X represents a hydrogen atom or an unsubstituted or substituted nonmetallic atom of Groups 14 to 16. Examples of the nonmetallic atom 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 Y in formula (Ar-1) above. 1 The substituents are the same as those that may be contained in the group.

[0046] In formula (Ar-3), D 5 and D 6 are each independently a single bond, -O-CO-, -C(=S)O-, or -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 is as described above.

[0047] In formula (Ar-3), SP 3 and SP 4 each independently represents a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a divalent linking group in which one or more -CH2- groups constituting the linear or branched alkylene group having 1 to 12 carbon atoms are substituted with -O-, -S-, -NH-, -N(Q)-, or -CO-, and Q represents a polymerizable group.

[0048] In formula (Ar-3), L 3 and L 4 each independently represents a monovalent organic group; L 3 and L 4and L in the above formula (1) 1 and L 2 At least one of these represents a polymerizable group.

[0049] In formulae (Ar-4) to (Ar-6), Ax represents an organic group having 2 to 30 carbon atoms and at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocycles. In formulae (Ar-4) to (Ar-6), Ax preferably represents an aromatic heterocycle, more preferably a benzothiazole ring. In formulae (Ar-4) to (Ar-6), Ay represents a hydrogen atom, an unsubstituted or optionally substituted alkyl group having 1 to 6 carbon atoms, or an organic group having 2 to 30 carbon atoms and at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocycles. In formulae (Ar-4) to (Ar-6), Ay preferably represents a hydrogen atom.

[0050] In formulas (Ar-4) to (Ar-6), Q 3 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may be unsubstituted or substituted. 3 preferably represents a hydrogen atom.

[0051] Among such Ar, preferred examples include the group (atomic group) represented by the above formula (Ar-4) or (Ar-6).

[0052] Specific examples of the liquid crystal compound represented by formula (1) are disclosed in International Publication No. 2018 / 123551, the disclosure of which is incorporated herein by reference. These compounds may be used alone or in combination of two or more.

[0053] The composition containing the 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 irradiation with ultraviolet light is preferred. Examples of photopolymerization initiators include α-carbonyl compounds (described in U.S. Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in U.S. Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (described in U.S. Pat. No. 2,722,512), polynuclear quinone compounds (described in U.S. Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketones (described in U.S. Pat. No. 3,549,367), oxadiazole compounds (described in U.S. Pat. No. 4,212,970), and acylphosphine oxide compounds (described in Japanese Patent Publication Nos. 63-40799, 5-29234, 10-95788, and 10-29997). The disclosure of this publication is incorporated herein by reference. The polymerization initiators may be used alone or in combination of two or more.

[0054] From the viewpoint of workability in forming a retardation layer, the composition containing a liquid crystal compound preferably contains a solvent. Any appropriate solvent can be used as the solvent, and an organic solvent is preferably used.

[0055] The composition containing a liquid crystal compound may further contain any other appropriate components, such as an antioxidant such as a phenolic antioxidant, a liquid crystal compound other than those described above, a leveling agent, a surfactant, a tilt angle control agent, an alignment aid, a plasticizer, and a crosslinking agent.

[0056] The liquid crystal alignment solidified layer can be formed by performing an alignment treatment on the surface of a predetermined substrate, applying a composition (coating liquid) containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment 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 a polarizing plate.

[0057] Any appropriate alignment treatment can be adopted as the alignment treatment. Specific examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. Specific examples of mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique deposition and photoalignment treatment. Any appropriate treatment conditions can be adopted for the various alignment treatments depending on the purpose.

[0058] The alignment of liquid crystal compounds is achieved by treating them at a temperature at which they exhibit a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compounds assume a liquid crystal state and are aligned in accordance with the alignment treatment direction on the substrate surface.

[0059] 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 alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

[0060] Details of the method for forming the orientation solidified layer are described in Japanese Patent Application Laid-Open No. 2006-163343, the disclosure of which is incorporated herein by reference.

[0061] C-2. First retardation layer having a laminated structure In one embodiment, the first retardation layer has a laminated structure of a liquid crystal compound alignment layer A and a liquid crystal compound alignment layer B. When the first retardation layer has a laminated structure, one of the liquid crystal alignment layer A and the liquid crystal alignment layer B can function as a λ / 4 plate, and the other can function as a λ / 2 plate. For example, when the liquid crystal alignment layer A functions as a λ / 2 plate and the liquid crystal alignment layer B functions as a λ / 4 plate, the Re(550) of the liquid crystal alignment layer A is preferably 200 nm to 300 nm, more preferably 200 nm to 270 nm, even more preferably 210 nm to 260 nm, and particularly preferably 230 nm to 260 nm. The Re(550) of the liquid crystal alignment layer B is preferably 100 nm to 200 nm, more preferably 100 nm to 170 nm, even more preferably 110 nm to 150 nm, and particularly preferably 110 nm to 130 nm.

[0062] The thickness of Layer A can be adjusted, for example, to obtain a desired in-plane retardation of the λ / 2 plate. The thickness of Layer A is, for example, 2.0 μm to 4.0 μm. The thickness of Layer B can be adjusted, for example, to obtain a desired in-plane retardation of the λ / 4 plate. The thickness of Layer B is, for example, 0.5 μm to 2.5 μm. In this embodiment, the angle formed between the slow axis of Layer A and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 12° to 16°. The angle formed between the slow axis of Layer B and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably 72° to 76°. When the first retardation layer has a laminated structure, each layer (for example, layer A and layer B) may exhibit an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the retardation value hardly changes depending on the wavelength of the measurement light.

[0063] The retardation layer (when having a laminated structure, at least one layer) typically exhibits a refractive index characteristic where nx > ny = nz. Note that "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, ny > nz or ny < nz may occur. The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3.

[0064] In this embodiment, examples of the liquid crystal compound used for the first retardation layer include liquid crystal compounds (nematic liquid crystals) whose liquid crystal phase is a nematic phase. As such liquid crystal compounds, for example, liquid crystal polymers and liquid crystal monomers can be used. The mechanism for the manifestation of liquid crystallinity of the liquid crystal compound may be either lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer may each be used alone or in combination.

[0065] When the liquid crystal compound is a liquid crystal monomer, it is preferable that the liquid crystal monomer is a polymerizable monomer and a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After aligning the liquid crystal monomer, for example, by polymerizing or crosslinking the liquid crystal monomers with each other, the alignment state can be fixed thereby. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, in the formed retardation layer, for example, a transition from a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change peculiar to the liquid crystalline compound does not occur. As a result, the retardation layer becomes an extremely stable retardation layer that is not affected by temperature changes.

[0066] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on its type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and even more preferably 60°C to 90°C.

[0067] Any suitable liquid crystal monomer can be used as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US 5,211,877), EP 66137 (US 4,388,453), WO 93 / 22397, EP 0261712, DE 19504224, DE 4408171, and GB 2280445 can be used. Specific examples of such polymerizable mesogenic compounds include BASF's LC242 (trade name), Merck's E7 (trade name), and Wacker-Chem's LC-Sillicon-CC3767 (trade name). Nematic liquid crystal monomers are preferred as the liquid crystal monomer. Specific examples of liquid crystal compounds and details of the method for forming the alignment solidified layer are as described above.

[0068] Although the case where the liquid crystal alignment solidified layer A functions as a λ / 2 plate and the liquid crystal alignment solidified layer B functions as a λ / 4 plate has been described, the liquid crystal alignment solidified layer A may function as a λ / 4 plate and the liquid crystal alignment solidified layer B may function as a λ / 4 plate. Also, the angle between the slow axis of the liquid crystal alignment solidified layer A and the absorption axis of the polarizer may be approximately 75°, and the angle between the slow axis of the liquid crystal alignment solidified layer B and the absorption axis of the polarizer may be approximately 15°.

[0069] D. Second retardation layer The second retardation layer 30 is preferably composed of a resin film containing a polymer exhibiting negative birefringence. Here, "exhibiting negative birefringence" means that when the polymer is oriented by stretching or the like, the refractive index in the stretching direction becomes relatively small. In other words, the refractive index in the direction perpendicular to the stretching direction becomes large. By being composed of a resin film containing a polymer exhibiting negative birefringence, the second retardation layer can reduce the change in retardation due to dimensional shrinkage of the polarizing plate. Therefore, the change in retardation of the retardation layer-attached polarizing plate in a high-temperature environment can be suppressed, and in-plane reflection hue unevenness can be suppressed.

[0070] The second retardation layer is preferably a so-called positive C plate whose refractive index characteristics satisfy the relationship nz>nx=ny. By using a positive C plate as the second retardation layer, reflection in oblique directions can be effectively prevented, enabling the anti-reflection function to have a wide viewing angle. The thickness direction retardation Rth(550) of the second retardation layer is preferably −10 nm to −200 nm, more preferably −20 nm to −180 nm, even more preferably −30 nm to −160 nm, and particularly preferably −40 nm to −140 nm. Here, “nx=ny” encompasses 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 the second retardation layer can be less than 10 nm.

[0071] The thickness of the second retardation layer 30 can be set to any appropriate thickness. The thickness of the second retardation layer is preferably 1 μm to 30 μm, more preferably 2 μm to 20 μm, and even more preferably 3 μm to 8 μm.

[0072] Examples of polymers that exhibit negative birefringence include polymers in which a chemical bond or functional group with large polarization anisotropy, such as an aromatic ring and / or a carbonyl group, has been introduced into the side chain. Specific examples include acrylic resins, styrene resins, and maleimide resins. Preferably, at least one polymer selected from the group consisting of acrylic resins, styrene resins, and maleimide resins can be used, and more preferably, a styrene resin can be used. Only one type of polymer exhibiting negative birefringence may be used, or two or more types may be used in combination.

[0073] The acrylic resin can be obtained by, for example, addition polymerization of acrylate monomers, and examples of the acrylic resin include polymethyl methacrylate (PMMA), polybutyl methacrylate, and polycyclohexyl methacrylate.

[0074] Styrenic resins can be obtained, for example, by addition polymerization of styrene monomers such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, 2,5-dichlorostyrene, and pt-butylstyrene.

[0075] The maleimide resin can be obtained, for example, by addition polymerization of a maleimide monomer. Examples of maleimide monomers include N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N-(2-propylphenyl)maleimide, N-(2-isopropylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-dipropylphenyl)maleimide, N-(2,6-diisopropylphenyl)maleimide, N-(2-methyl-6-ethylphenyl)maleimide, N-(2-chlorophenyl)maleimide, N-(2,6-dichlorophenyl)maleimide, N-(2-bromophenyl)maleimide, N-(2,6-dibromophenyl)maleimide, N-(2-biphenyl)maleimide, and N-(2-cyanophenyl)maleimide. Maleimide monomers are available from, for example, Tokyo Chemical Industry Co., Ltd.

[0076] In addition polymerization, the birefringence properties of the resulting resin can be controlled by, for example, substituting side chains or carrying out maleimide or grafting reactions after polymerization.

[0077] The polymer exhibiting negative birefringence may be copolymerized with other monomers. By copolymerizing other monomers, brittleness, moldability, and heat resistance can be improved. Examples of such other monomers include olefins such as ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, and 1-hexene; acrylonitrile; (meth)acrylates such as methyl acrylate and methyl methacrylate; maleic anhydride; and vinyl esters such as vinyl acetate.

[0078] When the polymer exhibiting negative birefringence is a copolymer of the styrene-based monomer and the other monomer, the blending ratio of the styrene-based monomer is preferably 50 mol % to 80 mol %. When the polymer exhibiting negative birefringence is a copolymer of the maleimide-based monomer and the other monomer, the blending ratio of the maleimide-based monomer is preferably 2 mol % to 50 mol %. By blending in such a range, a polymer film excellent in toughness and moldability can be obtained.

[0079] As the polymer exhibiting negative birefringence, preferably used are styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-(meth)acrylate copolymer, styrene-maleimide copolymer, vinyl ester-maleimide copolymer, olefin-maleimide copolymer, etc. These can be used alone or in combination of two or more. These polymers exhibit high negative birefringence and can have excellent heat resistance. These polymers are available, for example, from Nova Chemical Japan, Arakawa Chemical Industries, Ltd., etc.

[0080] As the polymer exhibiting negative birefringence, a polymer having a repeating unit represented by the following general formula (II) is preferably used. Such a polymer exhibits even higher negative birefringence and can have excellent heat resistance and mechanical strength. Such a polymer can be obtained, for example, by using an N-phenyl-substituted maleimide in which a phenyl group having a substituent at least at the ortho position is introduced as the N-substituent of the maleimide-based monomer as the starting material. [ka]

[0081] In the general formula (II), R1 to R5 each independently represent a hydrogen atom, a halogen atom, a carboxylic acid, a carboxylic acid ester, a hydroxyl group, a nitro group, or a linear or branched alkyl or alkoxy group having 1 to 8 carbon atoms (provided that R1 and R5 are not both hydrogen atoms), R6 and R7 represent a hydrogen atom or a linear or branched alkyl or alkoxy group having 1 to 8 carbon atoms, and n represents an integer of 2 or greater.

[0082] The polymer exhibiting negative birefringence is not limited to the above, and for example, cyclic olefin copolymers such as those disclosed in JP-A-2005-350544 can also be used. Furthermore, compositions containing polymers and inorganic fine particles such as those disclosed in JP-A-2005-156862 and JP-A-2005-227427 can also be suitably used. Furthermore, these can also be used after being modified by copolymerization, branching, crosslinking, molecular end modification (or blocking), stereoregular modification, etc.

[0083] The resin composition forming the second retardation layer may further contain any appropriate additives as needed. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, UV absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, thickeners, etc. The type and content of additives can be appropriately determined depending on the purpose. The content of additives is typically about 3 to 10 parts by weight per 100 parts by weight of the total solid content of the resin composition. If the content of additives is excessively high, the transparency of the polymer film may be impaired or the additives may bleed from the surface of the polymer film.

[0084] Any appropriate molding method can be used to form the second retardation layer. Examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, and solvent casting. Among these, extrusion molding and solvent casting are preferred because they can provide a retardation film with high smoothness and excellent optical uniformity. Specifically, extrusion molding involves heating and melting a resin composition containing the thermoplastic resin, plasticizer, additives, and the like, extruding the resulting composition into a thin film onto the surface of a casting roll using a T-die or the like, and then cooling the resulting composition to form a film. Solvent casting involves degassing a concentrated solution (dope) of the resin composition in a solvent, casting the resulting solution into a uniform thin film on the surface of a metallic endless belt or rotating drum, or a plastic substrate, and evaporating the solvent to form a film. The molding conditions can be appropriately set depending on the composition and type of resin used, the molding method, and the like.

[0085] E. Adhesive layer Any suitable adhesive can be used as the adhesive constituting the adhesive layer provided as the outermost layer (the adhesive layer between the image display device). 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, and cellulose-based adhesives. Among these adhesives, those that have excellent optical transparency, appropriate adhesive properties such as wettability, cohesion, and adhesion, and excellent weather resistance and heat resistance are preferably used. Acrylic-based adhesives are preferred as they exhibit these characteristics.

[0086] F. Image display device The retardation layer-attached polarizing plate described in the above items A to E can be applied to an image display device. Accordingly, embodiments of the present invention encompass image displays using such retardation layer-attached polarizing plates. Representative examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (e.g., 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 described in the above items A to E on its viewing side. The retardation layer-attached polarizing plate is laminated so that the retardation layer faces the image display cell (e.g., liquid crystal cell, organic EL cell, inorganic EL cell) side (so that the polarizer faces the viewing side). [Example]

[0087] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are by weight.

[0088] (1) Thickness Thicknesses of 10 μm or less were measured using an interference film thickness meter (Otsuka Electronics Co., Ltd., product name "MCPD-3000"), and thicknesses of more than 10 μm were measured using a digital micrometer (Anritsu Corporation, product name "KC-351C").

[0089] (2) Uneven Reflection Hue The polarizing plates with a retardation layer obtained in Examples and Comparative Examples were cut into a size of 60 mm in length and 130 mm in width to prepare samples. The portion of the sample with a length of 30 mm and a width of 25 mm was designated as measurement position A, the portion with a length of 30 mm and a width of 65 mm was designated as measurement position B, and the portion with a length of 30 mm and a width of 105 mm was designated as measurement position C. Next, the adhesive layer of the retardation layer-attached polarizing plate was laminated onto a 0.5 mm thick glass plate (80 mm × 150 mm). The retardation layer-attached polarizing plate laminated to the glass plate was then placed under a temperature of 80°C for 500 hours. The hue a* and hue b* values ​​at measurement positions A, B, and C were measured using a spectrophotometer (Konica Minolta, product name: CM-26d). The hue a* and hue b* values ​​at each measurement position were plotted, and the results for measurement positions A and B, and B and C, were compared. The value with the larger hue difference (the larger distance between the plots) was taken as the hue unevenness of each sample.

[0090] (3) Phase difference change The polarizing plates with retardation layers obtained in the examples and comparative examples were cut into samples with a width of 15 mm and a length of 200 mm. A tension meter (manufactured by MyCarbon, product name: Digital Luggage Scale) was used to apply tension to the obtained samples in the longitudinal direction. The in-plane retardation was measured using a retardation measuring device (manufactured by Oji Scientific Instruments, product name: KOBRA-WPR) at tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg. The retardation measured at each tension was plotted, and the slope was calculated to obtain the retardation change value.

[0091] [Production Example 1: Preparation of polarizing plate] 1. Polarizer Fabrication A long roll of a 30 μm-thick polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000") was uniaxially stretched in the longitudinal direction by 5.9 times using a roll stretching machine, while simultaneously undergoing swelling, dyeing, crosslinking, and washing processes, and finally drying, to produce a 12 μm-thick polarizer. Specifically, the film was stretched 2.2 times while being swelled in pure water at 20°C. Then, the film was stretched 1.4 times while being dyed in a 30°C aqueous solution containing iodine and potassium iodide at a weight ratio of 1:7, with the iodine concentration adjusted so that the resulting polarizer had a single transmittance of 45.0%. Furthermore, a two-stage crosslinking process was employed. In the first stage, the film was stretched 1.2 times while being treated in a 40°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the first stage was 5.0 wt % and the potassium iodide content was 3.0 wt %. In the second stage, the film was stretched 1.6 times while being treated in a 65°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the second stage was 3.7 wt % and the potassium iodide content was 5.0 wt %. The cleaning treatment was carried out with an aqueous potassium iodide solution at 20° C. The potassium iodide content of the aqueous solution used for the cleaning treatment was 3.1 wt %. Finally, the film was dried at 70° C. for 5 minutes to obtain a polarizer.

[0092] 2. Preparation of Polarizing Plates 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 a UV-curable adhesive. Specifically, the curable adhesive was applied so that the total thickness was 1.0 μm, and the films were attached using a roller. The adhesive was then cured by irradiating UV rays from the protective layer side. The HC-COP film was a cycloolefin (COP) film (manufactured by Zeon Corporation, product name "ZF12," thickness 25 μm) with a hard coat (HC) layer (thickness 2 μm), and the COP film was attached to the polarizer side. The resin substrate was then peeled off to obtain a polarizing plate having a configuration of protective layer (HC layer / COP film) / adhesive layer / polarizer.

[0093] [Production Example 2: Preparation of First Retardation Layer A (Single First Retardation Layer)] 55 parts by weight of a compound represented by the following formula (I), 25 parts by weight of a compound represented by the following formula (II), and 20 parts by weight of a compound represented by formula (III) were added to 400 parts by weight of cyclopentanone (CPN), then heated to 60°C and stirred to dissolve. The solution of the above compounds was then returned to room temperature, and 3 parts by weight of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 parts by weight of Megafac F-554 (manufactured by DIC Corporation), and 0.1 parts by weight of p-methoxyphenol (MEHQ) were added to the solution and further stirred. The solution after stirring was transparent and homogeneous. The resulting solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. A polyimide solution for an alignment film was spin-coated onto a 0.7 mm-thick glass substrate, 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 using a commercially available rubbing device to form an alignment film. Next, the polymerizable composition obtained above was applied to the substrate (substantially an alignment film) by spin coating and dried for 2 minutes at 100° C. After the obtained coating film was cooled to room temperature, it was heated at 30 mW / cm using a high-pressure mercury lamp. 2 The film was then irradiated with ultraviolet light at an intensity of 1000 nm for 30 seconds to obtain a first retardation layer (thickness 3 μm) which was an alignment-solidified layer of the liquid crystal compound. The in-plane retardation Re(550) of the first retardation layer was 130 nm. The Re(450) / Re(550) of the first retardation layer was 0.851, showing reverse dispersion wavelength characteristics. The first retardation layer can function as a λ / 4 plate. [ka] [ka]

[0094] [Production Example 3: Preparation of second retardation layer] An autoclave equipped with a stirrer, condenser, nitrogen inlet, and thermometer was charged with 48 parts by weight of hydroxypropyl methylcellulose (Shin-Etsu Chemical Co., Ltd., trade name: Metrose 60SH-50), 15,601 parts by weight of distilled water, 8,161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of the polymerization initiator t-butyl peroxypivalate. Nitrogen bubbling was performed for 1 hour, followed by stirring at 49°C for 24 hours to carry out radical suspension polymerization. The mixture was then cooled to room temperature, and the resulting suspension containing polymer particles was centrifuged. The resulting polymer was washed twice with distilled water and twice with methanol and then dried under reduced pressure. The resulting fumarate ester-based resin was dissolved in a toluene-methyl ethyl ketone mixed solution (toluene / methyl ethyl ketone 50% / 50% by weight) to prepare a 20% solution. Furthermore, 5 parts by weight of tributyl trimellitate as a plasticizer was added to 100 parts by weight of the fumaric acid ester resin to prepare a dope. A biaxially stretched polyester (polyethylene terephthalate / isophthalate copolymer) film (75 μm thick) was used as the support film. The prepared dope was applied to the support film to a dry thickness of 5 μm and dried at 140°C. The dried coating film (positive C plate) had an Re(550) of 0 nm and an Rth(550) of -75 nm.

[0095] [Production Example 4: Preparation of first retardation layer B (first retardation layer having laminated structure)] A liquid crystal composition (coating liquid) was prepared by dissolving 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF under the trade name "Paliocolor LC242" and represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF under the trade name "Irgacure 907") in 40 g of toluene. [ka] The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed with a rubbing cloth to perform an alignment treatment. The direction of the alignment treatment was set to be 15° from the viewing side with respect to the direction of the absorption axis of the polarizer when it was attached to the polarizing plate. The above liquid crystal coating solution was applied to this alignment-treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer thus formed was irradiated with 1 mJ / cm using a metal halide lamp. 2 The liquid crystal layer was cured by irradiating it with light, forming a liquid crystal alignment layer A on the PET film. The liquid crystal alignment layer A had a thickness of 2.5 μm and an in-plane retardation Re(550) of 270 nm. Furthermore, the liquid crystal alignment layer A exhibited a refractive index characteristic of nx>ny=nz.

[0096] A liquid crystal alignment layer B was formed on a PET film in the same manner as above, except that the coating thickness was changed and the alignment treatment direction was set to a 75° angle relative to the absorption axis of the polarizer when viewed from the viewing side. The thickness of the liquid crystal alignment layer B was 1.5 μm, and the in-plane retardation Re(550) was 140 nm. Furthermore, the liquid crystal alignment layer B exhibited refractive index characteristics of nx>ny=nz.

[0097] [Example 1] A protective layer (triacetyl cellulose (TAC) film, thickness: 20 μm) was attached to the polarizer of the polarizing plate obtained in Production Example 1 via an adhesive layer, thereby obtaining a polarizing plate having a protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / protective layer (TAC) structure. Separately, the liquid crystal alignment solidified layer A and the liquid crystal alignment solidified layer B obtained in Production Example 4 were transferred (laminated) in this order so that the angle between the absorption axis of the polarizer and the slow axis of the alignment solidified layer A was 15°, and the angle between the absorption axis of the polarizer and the slow axis of the alignment solidified layer B was 75°. The alignment solidified layer A and the alignment solidified layer B were laminated via an ultraviolet-curable adhesive (thickness after curing: 1 μm). Next, an ultraviolet-curable adhesive (thickness after curing: 1 μm) was applied to the liquid crystal alignment solidified layer B, and the second retardation layer obtained in Production Example 3 was laminated thereon to obtain a laminate of liquid crystal alignment solidified layer A / adhesive layer / liquid crystal alignment solidified layer B / adhesive layer / second retardation layer. Next, the TAC side surface of the obtained polarizing plate was laminated to the liquid crystal alignment solidified layer A of the above laminate via an acrylic adhesive layer (thickness 5 μm). Next, the substrate of the second retardation layer was peeled off. After that, an acrylic adhesive (thickness 26 μm) was applied to the substrate-released surface of the second retardation layer to obtain a retardation layer-attached polarizing plate having a configuration of protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / protective layer (TAC) / adhesive layer / first retardation layer (liquid crystal alignment solidified layer A / adhesive layer / liquid crystal alignment solidified layer B) / adhesive layer / second retardation layer / adhesive layer. The obtained polarizing plate was subjected to the above evaluations. The results are shown in Table 1.

[0098] (Comparative Example 1) A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the second retardation layer was not laminated. The obtained polarizing plate was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0099] [Production Example 5: Preparation of a positive C plate as a liquid crystal alignment solidified layer] A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (the numbers 65 and 35 in the formula indicate the mole percentage of the monomer unit, and are conveniently expressed as a block polymer; weight-average molecular weight: 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a PET substrate that had been subjected to vertical alignment treatment using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. The liquid crystal layer was irradiated with ultraviolet light to harden it, forming a retardation layer (3 μm thick) exhibiting a refractive index characteristic of nz>nx=ny on the substrate. [ka]

[0100] (Comparative Example 2) A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the retardation layer obtained in Production Example 5 was used instead of the second retardation layer obtained in Production Example 3. The obtained polarizing plate was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0101] [Example 2] A protective layer (triacetyl cellulose (TAC) film, thickness: 20 μm) was attached to the polarizer of the polarizing plate obtained in Production Example 1 via an adhesive layer, thereby obtaining a polarizing plate having a protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / protective layer (TAC) structure. Separately, the first retardation layer A obtained in Production Example 2 was attached to the protective layer (TAC) of the polarizing plate so that the angle between the absorption axis of the polarizer and the slow axis of the first retardation layer A was 45°. The first retardation layer and the protective layer (TAC) were laminated via an ultraviolet-curable adhesive (thickness after curing: 1 μm). Next, the TAC side surface of the obtained polarizing plate was laminated to a first retardation layer via an acrylic adhesive layer (thickness: 5 μm). The substrate of the second retardation layer was then peeled off. An acrylic adhesive (thickness: 26 μm) was then applied to the substrate-released surface of the second retardation layer to obtain a retardation layer-attached polarizing plate having a configuration of protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / protective layer (TAC) / adhesive layer / first retardation layer / adhesive layer / second retardation layer / adhesive layer. The obtained polarizing plate was subjected to the above evaluations. The results are shown in Table 1.

[0102] (Comparative Example 3) A polarizing plate with a retardation layer was obtained in the same manner as in Example 2, except that the second retardation layer was not laminated. The obtained polarizing plate was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0103] Comparative Example 4 A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the retardation layer obtained in Production Example 5 was used instead of the second retardation layer obtained in Production Example 3. The obtained polarizing plate was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0104] [Table 1]

[0105] [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, and in-plane unevenness of the reflected hue was suppressed. [Industrial Applicability]

[0106] The retardation layer-attached polarizing plate of the present invention is suitably used in image displays such as liquid crystal displays, organic EL displays, and inorganic EL displays. [Explanation of symbols]

[0107] 10 Polarizing plate 11 Polarizer 12 Protective layer 13 Protective layer 20 First retardation layer 30 Second retardation layer 100 Polarizing plate with retardation layer 101 Polarizing plate with retardation layer

Claims

1. a polarizing plate including a polarizer having a thickness of 12 μm or more; a first retardation layer which is a layer in which a liquid crystal compound is aligned and solidified; a second retardation layer formed of a resin film containing a polymer exhibiting negative birefringence; The thickness of the second retardation layer is 3 μm to 8 μm, The polarizing plate with a retardation layer, wherein the second retardation layer is a positive C plate.

2. 2. The polarizing plate with a retardation layer according to claim 1, wherein the second retardation layer is adjacent to the first retardation layer.

3. 3. The polarizing plate with a retardation layer according to claim 1, wherein the polymer exhibiting negative birefringence is at least one selected from the group consisting of acrylic resins, styrene resins, and maleimide resins.

4. The in-plane retardation of the first 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.

5. 5. The polarizing plate with a retardation layer according to claim 4, wherein the angle formed between the slow axis of the first retardation layer and the absorption axis of the polarizer is 40° to 50°.

6. the first retardation layer has a laminated structure of an alignment and solidification layer A of a liquid crystal compound and an alignment and solidification layer B of a liquid crystal compound, 4. The polarizing plate with a retardation layer according to claim 1, wherein the alignment fixed layer A functions as a λ / 2 plate, and the alignment fixed layer B functions as a λ / 4 plate.

7. 7. The retardation layer-attached polarizing plate according to claim 6, wherein the angle between the slow axis of the alignment and solidified layer A of the liquid crystal compound and the absorption axis of the polarizer is 70° to 80°, and the angle between the slow axis of the alignment and solidified layer B of the liquid crystal compound and the absorption axis of the polarizer is 10° to 30°.

8. An image display device comprising the retardation layer-attached polarizing plate according to claim 1 .

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