Polarizing plate set and LCD panel

Abstract

Liquid crystal panels are required to have improved contrast at a given viewing angle. [Solution] This is a set of polarizing plates to be attached to both sides of a liquid crystal cell having a liquid crystal layer containing liquid crystal molecules homogeneously aligned in the absence of an electric field. The set includes a first polarizing plate (10) disposed on one side of the liquid crystal cell and a second polarizing plate (20) disposed on the other side of the liquid crystal cell. The first polarizing plate (10) includes a first polarizer (31) and a retardation layer (40). The retardation layer (40) is disposed between the liquid crystal cell and the first polarizer (31), and the retardation layer (40) satisfies formulas (1) to (3). The second polarizing plate (20) includes a second polarizer (51) and a protective film (52). The protective film (52) is disposed between the liquid crystal cell and the second polarizer (51), and the protective film (52) satisfies formulas (4) to (6). The slow axis of the retardation layer (40) is approximately parallel to or approximately perpendicular to the absorption axis of the first polarizer (31).

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate set and a liquid crystal panel. [Background technology]

[0002] Liquid crystal display devices (LCDs) are widely used not only in LCD televisions but also in mobile applications such as personal computers and mobile phones, and in-vehicle applications such as car navigation systems. Typically, LCD displays have a liquid crystal panel member in which polarizing plates are attached to both sides of a liquid crystal cell with an adhesive, and display is achieved by controlling light from a backlight member with the liquid crystal panel member. In recent years, organic electroluminescence (EL) display devices have also begun to be widely used in mobile applications such as televisions and mobile phones, and in-vehicle applications such as car navigation systems, similar to LCD displays. In LCD displays, retardation films are used to provide a function of widening the viewing angle.

[0003] Polarizing plates are increasingly being installed in vehicles as optical elements that make up liquid crystal display devices. Polarizing plates used in in-vehicle display devices are required to have a wide viewing angle so that the display can be clearly seen, especially from the driver's seat. In particular, in-plane switching (IPS) liquid crystal cells, in the absence of an electric field, the liquid crystal molecules are homogeneously aligned in a direction approximately parallel to the substrate surface. When a horizontal electric field is applied, the liquid crystal molecules are rotated in a plane parallel to the substrate surface, controlling light transmission (white display) and blocking (black display). In-plane switching liquid crystal panels, such as IPS panels, in which the liquid crystal molecules are homogeneously aligned in the absence of an electric field have excellent viewing angle characteristics.

[0004] Patent Document 1 describes a polarizing plate including a retardation film made of a cyclic olefin resin film in order to widen the viewing angle. However, further improvement in viewing angle characteristics is required, and one indicator is to improve the contrast at an azimuth angle θ of 42.4° and an elevation angle φ of 23.4°. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5383594 Summary of the Invention [Problem to be solved by the invention]

[0006] The viewing angle characteristics of in-vehicle LCD devices need to be further improved. For example, there is a demand for further improvement in contrast at an azimuth angle of θ42.4° and an elevation angle of φ23.4°. [Means for solving the problem]

[0007] The present invention provides the following polarizing plate set and liquid crystal panel. [Invention 1] A set of polarizing plates to be attached to both sides of a liquid crystal cell having a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field, a first polarizing plate disposed on one surface of the liquid crystal cell and a second polarizing plate disposed on the other surface of the liquid crystal cell; the first polarizing plate has a first polarizer and a retardation layer, the retardation layer is disposed between the liquid crystal cell and the first polarizer, The retardation layer satisfies the following formulas (1) to (3), ny

[0590] <nz

[0590] <nx

[0590] (1) 0.8≦Re

[0480] / Re

[0590] ≦1.2 (2) 100nm≦Re

[0590] ≦150nm (3) the second polarizing plate includes a second polarizer and a protective film, the protective film is disposed between the liquid crystal cell and the second polarizer, The protective film satisfies the following formulas (4) to (6): 0nm≦Re

[0550] ≦5nm (4) -5nm≦Rth

[0550] ≦5nm (5) -30nm≦Rth

[0450] ≦-1.0nm (6) A set of polarizing plates, wherein the slow axis of the retardation layer is approximately parallel to or approximately perpendicular to the absorption axis of the first polarizer.

[0008] [Invention 2] The set of polarizing plates according to [Invention 1], wherein the crossed transmittance of the first polarizer and the second polarizer at a wavelength of 410 nm is 0.05% or less.

[0009] [Invention 3] The set of polarizing plates according to [Invention 1] or [Invention 2], wherein the retardation layer has a positive A plate and a positive C plate.

[0010] [Invention 4] a liquid crystal cell having a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field; a first polarizing plate disposed on one surface of the liquid crystal cell; a second polarizing plate disposed on the other surface of the liquid crystal cell, the first polarizing plate has a first polarizer and a retardation layer, the retardation layer is disposed between the liquid crystal cell and the first polarizer, The retardation layer satisfies the following formulas (1) to (3), ny

[0590] <nz

[0590] <nx

[0590] (1) 0.8≦Re

[0480] / Re

[0590] ≦1.2 (2) 100nm≦Re

[0590] ≦150nm (3) the second polarizing plate includes a second polarizer and a protective film, the protective film is disposed between the liquid crystal cell and the second polarizer, The protective film satisfies the following formulas (4) to (6): 0nm≦Re

[0550] ≦5nm (4) -5nm≦Rth

[0550] ≦5nm (5) -30nm≦Rth

[0450] ≦-1.0nm (6) a slow axis of the retardation layer is approximately parallel to or approximately perpendicular to an absorption axis of the first polarizer, The liquid crystal panel, wherein the absorption axis of the first polarizer and the absorption axis of the second polarizer are substantially perpendicular to each other. [Effects of the Invention]

[0011] According to the polarizing plate set of the present invention, the contrast of the liquid crystal panel can be further improved at a viewing angle of an azimuth angle θ of 42.4° and an elevation angle φ of 23.4°. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1(a) is a schematic cross-sectional view of one polarizing plate of the set of polarizing plates of the present invention, and FIG. 1(b) is a schematic cross-sectional view of the other polarizing plate of the set of polarizing plates of the present invention. [Figure 2] FIG. 2 is a schematic perspective view showing an example of a preferable axial configuration of the liquid crystal panel of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The polarizing plate set of the present invention will be described below. <Polarizing plate set> As shown in Figures 1(a) and (b), the polarizing plate set consists of a first polarizing plate 10 placed on one side of the liquid crystal cell 60 (see Figure 2), which is the viewing side, and a second polarizing plate 20 placed on the other side of the liquid crystal cell 60, which is the back side.

[0014] <First polarizing plate> The first polarizing plate 10 has a polarizer (hereinafter also referred to as the first polarizer 31), a protective film (hereinafter also referred to as the first protective film 32) laminated on one side of the first polarizer 31, and a retardation layer 40 laminated on the other side.

[0015] [First polarizer] The present invention uses a polarizer formed by adsorbing and aligning a dichroic dye such as iodine in a polyvinyl alcohol (hereinafter also referred to as PVA)-based resin layer. Such polarizers are generally formed by using a PVA-based resin film, dyeing this PVA-based resin film with a dichroic dye such as iodine, and uniaxially stretching it, or by using a laminated film obtained by applying a coating liquid containing a PVA-based resin onto a base film, dyeing the PVA-based resin layer, which is the coating layer of this laminated film, with a dichroic dye such as iodine, and uniaxially stretching the laminated film.

[0016] The polarizer is made of a PVA resin obtained by saponifying a polyvinyl acetate resin. Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other copolymerizable monomers. Examples of the other copolymerizable monomers include unsaturated carboxylic acids, olefins such as ethylene, vinyl ethers, and unsaturated sulfonic acids.

[0017] The saponification degree of the PVA resin is preferably about 85 mol% or more, more preferably about 90 mol% or more, and even more preferably about 99 mol% to 100 mol%. The polymerization degree of the PVA resin is 1,000 to 10,000, preferably 1,500 to 5,000. The PVA resin may be modified, and may be, for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, or the like, modified with aldehydes.

[0018] The thickness of the polarizer of this embodiment is preferably 5 to 50 μm, more preferably 8 to 28 μm, even more preferably 12 to 22 μm, and most preferably 12 to 15 μm. When the thickness of the polarizer is 5 μm or more, it becomes easy to achieve a configuration that achieves desired optical properties.

[0019] The first polarizer 31 preferably has a cross transmittance of 0.05% or less at a wavelength of 410 nm, and may be 0.03% or less, or may be 0.01% or less. The cross transmittance can be measured using a commercially available spectrophotometer.

[0020] [Method for manufacturing first polarizer] The method for producing a polarizer is not particularly limited, but typical examples include a method in which a polyvinyl alcohol-based resin film that has been wound in advance into a roll is fed and subjected to steps such as swelling, dyeing, crosslinking, stretching, color complementation, and washing with water, or a method including a step of applying a coating liquid containing a polyvinyl alcohol-based resin onto a substrate film to form a polyvinyl alcohol-based resin layer as a coating layer, and stretching the resulting laminate.

[0021] The swelling step is a treatment step in which the polyvinyl alcohol-based resin film is immersed in a swelling bath. This step can remove stains and blocking agents from the surface of the polyvinyl alcohol-based resin film, and also suppress uneven dyeing by swelling the polyvinyl alcohol-based resin film. The swelling bath typically uses a medium whose main component is water, distilled water, pure water, or the like. The swelling bath may contain appropriate additives such as surfactants and alcohols, according to conventional methods. Potassium iodide may also be used in the swelling bath to control the potassium content of the polarizing element. In this case, the concentration of potassium iodide in the swelling bath is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.5% by mass or less.

[0022] The temperature of the swelling bath is preferably about 10 to 60°C, more preferably about 15 to 45°C, and even more preferably about 18 to 30°C. The immersion time in the swelling bath cannot be determined in general because the degree of swelling of the polyvinyl alcohol-based resin film is affected by the temperature of the swelling bath, but is preferably about 5 to 300 seconds, more preferably about 10 to 200 seconds, and even more preferably about 20 to 100 seconds. The swelling step may be carried out only once, or may be carried out multiple times as necessary.

[0023] The dyeing process is a treatment process in which a polyvinyl alcohol-based resin film is immersed in a dye bath (iodine solution), allowing iodine or a dichroic substance such as a dichroic dye to be adsorbed and aligned in the polyvinyl alcohol-based resin film. The iodine solution is typically preferably an aqueous iodine solution containing iodine and an iodide as a solubilizing agent. Examples of iodides include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Among these, potassium iodide is preferred from the viewpoint of controlling the potassium content in the polarizing element.

[0024] The iodine concentration in the dye bath is preferably about 0.01 to 1 mass%, more preferably about 0.02 to 0.5 mass%, and the iodide concentration in the dye bath is preferably about 0.01 to 10 mass%, more preferably about 0.05 to 5 mass%, and even more preferably about 0.1 to 3 mass%.

[0025] The temperature of the dye bath is preferably about 10 to 50°C, more preferably about 15 to 45°C, and even more preferably about 18 to 30°C. The immersion time in the dye bath cannot be determined in general because the degree of dyeing of the polyvinyl alcohol-based resin film is affected by the temperature of the dye bath, but is preferably about 10 to 300 seconds, and more preferably about 20 to 240 seconds. The dyeing step may be carried out only once, or may be carried out multiple times as necessary.

[0026] The crosslinking step is a treatment step in which the polyvinyl alcohol-based resin film dyed in the dyeing step is immersed in a treatment bath (crosslinking bath) containing a boron compound. The boron compound crosslinks the polyvinyl alcohol-based resin film, allowing iodine molecules or dye molecules to be adsorbed to the crosslinked structure. Examples of boron compounds include boric acid, borate salts, and borax. The crosslinking bath is generally an aqueous solution, but may also be, for example, a mixed solution of water and an organic solvent miscible with water. In addition, the crosslinking bath preferably contains potassium iodide in order to control the potassium content in the polarizing element.

[0027] The concentration of the boron compound in the crosslinking bath is preferably about 1 to 15 mass%, more preferably about 1.5 to 10 mass%, and even more preferably about 2 to 5 mass%. When potassium iodide is used in the crosslinking bath, the concentration of potassium iodide in the crosslinking bath is preferably about 1 to 15 mass%, more preferably about 1.5 to 10 mass%, and even more preferably about 2 to 5 mass%.

[0028] The temperature of the crosslinking bath is preferably about 20 to 70° C., more preferably about 30 to 60° C. The immersion time in the crosslinking bath cannot be determined in general because the degree of crosslinking of the polyvinyl alcohol resin film is affected by the temperature of the crosslinking bath, but is preferably about 5 to 300 seconds, more preferably about 10 to 200 seconds. The crosslinking step may be carried out only once, or may be carried out multiple times as necessary.

[0029] The stretching step is a treatment step in which a polyvinyl alcohol-based resin film is stretched at least in one direction to a predetermined magnification. Generally, the polyvinyl alcohol-based resin film is uniaxially stretched in the conveying direction (longitudinal direction). The stretching method is not particularly limited, and either a wet stretching method or a dry stretching method can be used. The stretching step may be carried out only once, or may be carried out multiple times as necessary. The stretching step may be carried out at any stage in the production of a polarizing element.

[0030] The treatment bath (stretching bath) used in the wet stretching method can typically be water or a solvent such as a mixture of water and a water-miscible organic solvent. The stretching bath preferably contains potassium iodide to control the potassium ion content in the polarizing element. When potassium iodide is used in the stretching bath, the concentration of potassium iodide in the stretching bath is preferably about 0.1 to 15% by mass, more preferably about 2 to 10% by mass, and even more preferably about 3 to 6% by mass. Furthermore, the treatment bath (stretching bath) can contain a boron compound to prevent film breakage during stretching. In this case, the concentration of the boron compound in the stretching bath is preferably about 1 to 15% by mass, more preferably about 1.5 to 10% by mass, and even more preferably about 2 to 5% by mass.

[0031] The temperature of the stretching bath is preferably 25 to 80°C, more preferably 40 to 80°C, even more preferably 50 to 75°C, and particularly preferably 65 to 75°C. Increasing the temperature of the stretching bath facilitates retention of the second metal ions used in the metal ion treatment step described below in the PVA-based resin layer. Increasing the temperature of the stretching bath allows the temperature to be raised to near the softening point of PVA in the PVA-based resin layer or above the softening point of PVA. This is thought to result in a decrease in the crystalline proportion of PVA or a decrease in the size of the PVA crystals, thereby increasing the amount of second metal ion uptake. The immersion time in the stretching bath cannot be determined unconditionally because the degree of stretching of the polyvinyl alcohol-based resin film is affected by the temperature of the stretching bath, but is preferably about 10 to 800 seconds, more preferably about 30 to 500 seconds. The stretching step in the wet stretching method may be performed alone, or may be performed together with one or more of the swelling, dyeing, crosslinking, and washing steps, or a combination of these. When performed together with one or more of these steps, the crosslinking step is the step that is particularly suited to adjusting the treatment bath temperature to 65 to 75°C, which is optimal for the stretching step. When stretching is performed in multiple treatment baths, it is preferable that at least one of the treatment baths has a temperature of 65 to 75°C, and the immersion time in the treatment bath at 65 to 75°C is preferably 40 to 200 seconds.

[0032] (complementary color process) The color-complementing step is a process for adjusting the hue of the film. It can be carried out by immersing the film after the crosslinking step in a color-complementing bath (a color-complementing solution contained in a color-complementing tank) for a predetermined period of time and then removing it.

[0033] The complementary color solution may be an aqueous solution containing, for example, about 1 to 10 parts by mass of boric acid per 100 parts by mass of water. When the dichroic dye used in the dyeing process is iodine, the complementary color solution preferably contains an iodide in addition to boric acid, and the amount may be, for example, 1 to 30 parts by mass per 100 parts by mass of water. Examples of iodides include potassium iodide and zinc iodide. Two or more types of iodides may be contained. Furthermore, compounds other than iodides, such as sodium thiosulfate, potassium sulfite, and sodium sulfate, may also be present. Furthermore, a nitrate may also be present. The nitrate may include at least one selected from the group consisting of aluminum nitrate, copper nitrate, sodium nitrate, potassium nitrate, zinc nitrate, and magnesium nitrate. The nitrate preferably includes zinc nitrate.

[0034] For example, when iodine is used as the dichroic dye in the complementary color solution, the concentration can be such that the mass ratio of boric acid / iodide / water is 1 to 5 / 3 to 30 / 100. The temperature of the complementary color bath when the film is immersed is usually 10 to 45°C, and the immersion time of the film is usually 1 to 300 seconds, preferably 2 to 100 seconds.

[0035] The complementary color treatment may be carried out multiple times, for example, 2 to 5 times. In this case, the composition and temperature of each complementary color bath used may be the same or different as long as they are within the above ranges.

[0036] The cleaning step is a treatment step in which the PVA-based resin film is immersed in a cleaning bath, and foreign matter remaining on the surface of the PVA-based resin film can be removed. A medium containing water as a main component, such as water, distilled water, or pure water, is typically used for the cleaning bath. Furthermore, from the viewpoint of controlling the potassium content in the polarizing layer, the cleaning bath preferably contains potassium iodide. In this case, the concentration of potassium iodide in the cleaning bath is preferably about 1 to 10 wt %, more preferably about 1.5 to 4 wt %, and even more preferably about 1.8 to 3.8 wt %.

[0037] The temperature of the cleaning bath is preferably about 5 to 50°C, more preferably about 10 to 40°C, and even more preferably about 15 to 30°C. The immersion time in the cleaning bath cannot be determined in general because the degree of cleaning of the PVA resin film is affected by the temperature of the cleaning bath, but is preferably about 1 to 100 seconds, more preferably about 2 to 50 seconds, and even more preferably about 3 to 20 seconds. The cleaning step may be carried out only once, or may be carried out multiple times as necessary.

[0038] Finally, the PVA resin film washed in the washing step is dried to obtain a polarizing layer. Drying can be performed by any appropriate method, such as natural drying, air drying, or heat drying. The drying temperature is, for example, 30 to 100°C, and the drying time is, for example, 30 to 600 seconds.

[0039] In order to make the crossed transmittance of the first polarizer 31 at a wavelength of 410 nm 0.05% or less, for example, the iodine concentration in the dyeing step is set to 0.3% by mass or more, the amount of iodide in the complementary color step is set to 2 parts by mass or more per 100 parts by mass of water, and the maximum drying temperature in the drying step is set to 80° C. or more, thereby reducing the amount of polyiodine (I3 - / I5 - By keeping the cross transmittance at a wavelength of 410 nm at 0.05% or less, the blue tint in oblique viewing can be suppressed, resulting in a further improvement in viewing angle contrast.

[0040] [Phase difference layer] The retardation layer 40 satisfies the following formulas (1) to (3). ny

[0590] <nz

[0590] <nx

[0590] (1) 0.8≦Re

[0480] / Re

[0590] ≦1.2 (2) 100nm≦Re

[0590] ≦150nm (3) Here, nx[λ] is the refractive index in the x direction (in-plane slow axis direction) in the film plane at a wavelength of λ nm, ny[λ] is the refractive index in the y direction (in-plane fast axis direction) in the film plane at a wavelength of λ nm, and nz[λ] is the refractive index in the direction perpendicular to the film plane (thickness direction) at a wavelength of λ nm. The in-plane retardation value Re[λ] at a wavelength of λ nm is a value defined by the following formula (7). The retardation value Rth[λ] in the thickness direction at a wavelength of λ nm is a value defined by the following formula (8).

[0041] Re[λ]=(nx[λ]-ny[λ])×d (7) Rth[λ]={(nx[λ]+ny[λ]) / 2-nz[λ]}×d (8) Here, d is the thickness (nm) of the film. The retardation value in the in-plane direction and the retardation value in the thickness direction can be measured by the method described in the examples below.

[0042] The retardation layer 40 may be a single layer or may be configured of a laminated film of two or more layers. For example, a retardation layer combining a positive A plate 41 and a positive C plate 42 is preferably used. The slow axis of the retardation layer 40 is approximately parallel to or approximately perpendicular to the absorption axis of the first polarizer 31. "Approximately perpendicular" means that the angle between the two directions is within a range of, for example, 90°±3°. "Approximately parallel" means that the angle between the two directions is within a range of, for example, 0°±3°.

[0043] The positive A plate 41 used in the present invention refers to a retardation layer that satisfies the relationship nx

[0590] > ny

[0590] ≒ nz

[0590] . Here, ny

[0590] ≒ nz

[0590] indicates that it also includes the case where ny and nz are substantially equal at a wavelength of 590 nm. In the present invention, "substantially equal refractive indexes" means that the difference in refractive index is within 0.005.

[0044] The positive A plate 41 may be, for example, an olefin-based resin film formed using an olefin-based resin. Examples of olefin-based resins include resins that primarily contain structural units derived from chain aliphatic olefins such as ethylene and propylene, or alicyclic olefins such as norbornene and its substitution products (hereinafter, these may be collectively referred to as "norbornene-based monomers"). "Mainly containing structural units" means that the proportion of structural units contained in the resin, based on the mass of substance, is 50% or more. The olefin-based resin may be a copolymer using two or more types of monomers.

[0045] The positive A plate 41 is preferably a cyclic olefin resin film formed using a cyclic olefin resin, which is a resin primarily containing structural units derived from an alicyclic olefin. A typical example of the alicyclic olefin constituting the cyclic olefin resin is a norbornene monomer. Norbornene is a compound in which one carbon-carbon bond of norbornane is double-bonded, and is named bicyclo[2,2,1]hept-2-ene according to the IUPAC nomenclature. Examples of norbornene substitutions, assuming that the double bond positions of norbornene are the 1,2-positions, include 3-substituted, 4-substituted, and 4,5-disubstituted norbornenes, as well as dicyclopentadiene and dimethanooctahydronaphthalene.

[0046] The cyclic olefin resin may or may not have a norbornane ring as a constituent unit. Examples of norbornene monomers that form cyclic olefin resins that do not have a norbornane ring as a constituent unit include those that become five-membered rings upon ring opening, typically norbornene, dicyclopentadiene, 1- or 4-methylnorbornene, and 4-phenylnorbornene. When the cyclic olefin resin is a copolymer, the molecular arrangement is not particularly limited, and the copolymer may be a random copolymer, a block copolymer, or a graft copolymer.

[0047] More specific examples of cyclic olefin resins include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers, polymer modifications thereof obtained by adding maleic acid or cyclopentadiene, and hydrogenated polymers or copolymers thereof; addition polymers of norbornene-based monomers, and addition copolymers of norbornene-based monomers and other monomers. Examples of other monomers used in copolymerization include α-olefins, cycloalkenes, and non-conjugated dienes. The cyclic olefin resin may also be a copolymer using one or more norbornene-based monomers and other alicyclic olefins. Among these, preferred cyclic olefin resins are resins obtained by hydrogenating ring-opening polymers or ring-opening copolymers using norbornene-based monomers.

[0048] Commercially available cyclic olefin resins using the norbornene monomers include "Zeonex" and "Zeonor" sold by Zeon Corporation, and "Arton" sold by JSR Corporation. Films of these cyclic olefin resins and stretched films thereof are also commercially available, and examples of such products include "Zeonor Film" sold by Optes Inc., "Arton Film" sold by JSR Corporation, and "S-Cina" sold by Sekisui Chemical Co., Ltd.

[0049] The positive A plate 41 may be a film made of a mixed resin containing two or more types of olefin-based resins, or a film made of a mixed resin of an olefin-based resin and another thermoplastic resin. For example, a mixed resin containing two or more types of olefin-based resins may be a mixture of the above-mentioned cyclic olefin-based resin and a chain aliphatic olefin-based resin. When a mixed resin of an olefin-based resin and another thermoplastic resin is used, the other thermoplastic resin is appropriately selected depending on the purpose. Specific examples of other thermoplastic resins include polyvinyl chloride resins, cellulose resins, polystyrene resins, acrylonitrile / butadiene / styrene copolymer resins, acrylonitrile / styrene copolymer resins, (meth)acrylic resins, polyvinyl acetate resins, polyvinylidene chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polyarylate resins, liquid crystal resins, polyamideimide resins, polyimide resins, and polytetrafluoroethylene resins. These thermoplastic resins can be used alone or in combination of two or more. The thermoplastic resins can also be used after any suitable polymer modification. Examples of polymer modifications include copolymerization, crosslinking, molecular end modification, and stereoregularity impartation.

[0050] When a mixed resin of an olefin resin and another thermoplastic resin is used, the content of the other thermoplastic resin is usually about 50% by weight or less, preferably about 40% by weight or less, based on the total resin. By setting the content of the other thermoplastic resin within this range, a retardation film can be obtained that has a small absolute value of the photoelastic coefficient, good wavelength dispersion characteristics, and excellent durability, mechanical strength, and transparency.

[0051] The positive A plate 41 may contain other components as needed, such as residual solvents, stabilizers, plasticizers, antioxidants, antistatic agents, and ultraviolet absorbers. It may also contain a leveling agent to reduce surface roughness.

[0052] The positive A plate 41 preferably has an in-plane retardation value, and the in-plane retardation value Re

[0590] at a wavelength of 590 nm may be 100 nm or more, preferably 105 nm or more, more preferably 110 nm or more, or may be 150 nm or less, or may be 140 nm or less. The positive A plate 41 is preferably a stretched film.

[0053] Furthermore, the wavelength dispersion characteristics of the positive A plate 41 may be such that Re

[0480] / Re

[0590] is 0.8 or more, preferably 0.9 or more, and may be 1.2 or less, preferably 1.1 or less.

[0054] The thickness of the positive A plate 41 is not particularly limited, but is preferably 15 μm to 80 μm, more preferably 18 μm to 45 μm, and most preferably 20 μm to 30 μm. If the thickness of the retardation film is less than 15 μm, the film tends to be difficult to handle and to achieve a predetermined retardation value. On the other hand, if the thickness of the retardation film exceeds 80 μm, the film tends to be poor in processability, and the transparency tends to decrease and the weight of the resulting polarizing plate tends to increase.

[0055] The positive A plate 41 can be obtained by stretching a resin film formed using the above-mentioned resin. The resin film can be obtained, for example, by casting a solution containing the above-mentioned olefin-based resin or by melt extrusion. When a film is formed using a mixed resin of two or more kinds, the film formation method is not particularly limited, and examples include a method of producing a film by casting a homogeneous solution obtained by stirring and mixing resin components with a solvent in a predetermined ratio, and a method of melt-mixing resin components in a predetermined ratio and producing a film by melt extrusion.

[0056] Examples of stretching treatment for a resin film include known longitudinal uniaxial stretching, tenter transverse uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, etc. In the stretching treatment, the stretching ratio and stretching speed may be appropriately adjusted so as to obtain a desired retardation value, and various temperatures during stretching, such as a preheating temperature, a stretching temperature, a heat setting temperature, and a cooling temperature, and their patterns may be appropriately selected.

[0057] The retardation layer 40 is preferably composed of a laminate of the positive A plate 41 and the positive C plate 42. The positive C plate 42 is a retardation layer that satisfies nz

[0590] > nx

[0590] ≒ ny

[0590] . Here, nx

[0590] ≒ ny

[0590] indicates that it also includes the case where nx and ny are substantially equal at a wavelength of 590 nm.

[0058] A known plate can be used as the positive C plate 42. For example, the positive C plate 42 is preferably a solidified or hardened layer of a liquid crystal composition in which rod-shaped liquid crystal compositions are aligned in a homeotropic alignment.

[0059] Examples of liquid crystal compounds include liquid crystal compounds with a nematic liquid crystal phase (nematic liquid crystals). Examples of liquid crystal compounds that can be used include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound may exhibit liquid crystallinity through either lyotropy or thermotropy. Liquid crystal polymers and liquid crystal monomers may be used alone or in combination. Any appropriate liquid crystal monomer can be used as the liquid crystal monomer. Examples of polymerizable mesogen compounds that can be used include those 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. 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 liquid crystal monomers. Specific examples of liquid crystal compounds and details of the method for forming the alignment-solidified layer are described in JP-A-2006-163343, the disclosure of which is incorporated herein by reference.

[0060] The liquid crystal cured layer can be set so as to function optimally as the positive C plate 42. In other words, the thickness can be set so as to obtain desired optical characteristics. The thickness of the retardation layer is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and particularly preferably 0.5 to 5 μm.

[0061] The positive C plate 42 preferably has an in-plane retardation value Re

[0590] of substantially zero at a wavelength of 590 nm. An in-plane retardation value Re

[0590] of substantially zero at a wavelength of 590 nm means that the absolute value of the in-plane retardation value is 10 nm or less. Furthermore, the retardation value in the thickness direction of the positive C plate 42 at a wavelength of 590 nm may be −200 nm or more, preferably −170 nm or more, and more preferably −150 nm or more, or may be −10 nm or less, or −30 nm or less.

[0062] The retardation layer 40 is adjusted by combining the positive A plate 41 and the positive C plate 42 so as to satisfy the above formulas (1) to (3). 2, in one preferred embodiment, the first polarizer 31 is arranged so that the absorption axis (see arrow) direction of the first polarizer 31 and the slow axis (see arrow) direction of the positive A plate 41 included in the retardation layer 40 are parallel to each other. When laminated in this arrangement, the positive C plate 42 included in the retardation layer 40 is preferably arranged between the first polarizer 31 and the positive A plate 41 included in the retardation layer 40.

[0063] In another preferred embodiment, the first polarizer 31 is arranged so that the direction of the absorption axis (see arrow) of the first polarizer 31 and the direction of the slow axis of the positive A plate 41 included in the retardation layer 40 are perpendicular to each other. When laminated in such an arrangement, it is preferable that the positive C plate 42 included in the retardation layer 40 is arranged on the surface of the positive A plate 41 included in the retardation layer 40 opposite to the first polarizer 31.

[0064] [First protective film] The first protective film 32 is preferably made of a resin material that is excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, etc. Such protective film materials are not particularly limited, but examples include films made of methyl methacrylate resins, polyolefin resins, cyclic olefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, acrylonitrile-butadiene-styrene resins, acrylonitrile-styrene resins, polyvinyl acetate resins, polyvinylidene chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyamideimide resins, and polyimide resins.

[0065] These resins can be used alone or in combination of two or more. These resins can also be used after any appropriate polymer modification, such as copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and mixing, including reactions between different polymers.

[0066] Among these, it is preferable to use cellulose-based resins, (meth)acrylic-based resins, and polyethylene terephthalate-based resins as the material for the protective film. The cellulose-based resin refers to a cellulose organic acid ester or a cellulose mixed organic acid ester obtained from raw cellulose such as cotton linter or wood pulp (hardwood pulp or softwood pulp), in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose are substituted with acetyl groups, propionyl groups, and / or butyryl groups. Examples include cellulose acetate esters, propionate esters, butyrate esters, and mixed esters thereof. Among these, triacetyl cellulose film, diacetyl cellulose film, cellulose acetate propionate film, and cellulose acetate butyrate film are preferred.

[0067] A methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. A polymer containing 100% by weight of methyl methacrylate units is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

[0068] This methyl methacrylate resin can usually be obtained by polymerizing a monofunctional monomer containing methyl methacrylate as a main component, a polyfunctional monomer, a radical polymerization initiator, and a chain transfer agent in the presence of the monomer.

[0069] The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include methacrylic acid esters other than methyl methacrylate, such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate; acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; 2-(hydroxymethyl) Examples of suitable monomers include hydroxyacrylic acid esters such as methyl acrylate, methyl 3-(hydroxyethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, and butyl 2-(hydroxymethyl)acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrenes such as vinyltoluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. These monomers may be used alone or in combination of two or more.

[0070] The polyfunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetradecaethylene glycol (meth)acrylate, and other ethylene glycol or oligomers thereof in which both terminal hydroxyl groups are esterified with acrylic acid or methacrylic acid; propylene glycol or oligomers thereof in which both terminal hydroxyl groups are esterified with acrylic acid or methacrylic acid; and hydroxyl groups of dihydric alcohols such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, and butanediol di(meth)acrylate. with acrylic acid or methacrylic acid; bisphenol A, alkylene oxide adducts of bisphenol A, or halogen-substituted derivatives thereof, both terminal hydroxyl groups of which are esterified with acrylic acid or methacrylic acid; polyhydric alcohols such as trimethylolpropane and pentaerythritol, esterified with acrylic acid or methacrylic acid, and derivatives thereof, in which the epoxy group of glycidyl acrylate or glycidyl methacrylate is ring-opened and added to the terminal hydroxyl groups; dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, halogen-substituted derivatives thereof, and alkylene oxide adducts thereof, in which the epoxy group of glycidyl acrylate or glycidyl methacrylate is ring-opened and added; aryl (meth)acrylates; and diaryl compounds such as divinylbenzene. Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

[0071] Methyl methacrylate resins having such a composition may also be modified by a reaction between the functional groups copolymerized in the resin, such as an intramolecular chain demethanol condensation reaction between the methyl ester group of methyl acrylate and the hydroxyl group of methyl 2-(hydroxymethyl)acrylate, or an intramolecular chain dehydration condensation reaction between the carboxyl group of acrylic acid and the hydroxyl group of methyl 2-(hydroxymethyl)acrylate.

[0072] Such methyl methacrylate resins are readily available commercially, and examples thereof include Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrypet (manufactured by Mitsubishi Rayon Co., Ltd.), Delpet (manufactured by Asahi Kasei Corporation), Parapet (manufactured by Kuraray Co., Ltd.), and Acryview (manufactured by Nippon Shokubai Co., Ltd.).

[0073] The polyethylene terephthalate resin refers to a resin in which 80 mol % or more of the repeating units are composed of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. The other dicarboxylic acid components are not particularly limited, but examples thereof include isophthalic acid, p-β-oxyethoxybenzoic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis(4-carboxyphenyl)ethane, adipic acid, sebacic acid, and 1,4-dicarboxycyclohexane.

[0074] Examples of other diol components include, but are not limited to, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0075] These dicarboxylic acid components and diol components can be used in combination of two or more types as needed. Also, oxycarboxylic acids such as p-oxybenzoic acid can be used in combination. Furthermore, dicarboxylic acid components or diol components containing small amounts of amide bonds, urethane bonds, ether bonds, carbonate bonds, etc. may be used as other copolymerization components.

[0076] Methods for producing polyethylene terephthalate resins include direct polycondensation of terephthalic acid and ethylene glycol (and, if necessary, other dicarboxylic acids or other diols), transesterification of a dialkyl ester of terephthalic acid and ethylene glycol (and, if necessary, a dialkyl ester of another dicarboxylic acid or other diol), followed by polycondensation, and polycondensation of an ethylene glycol ester of terephthalic acid (and, if necessary, other dicarboxylic acids) (and, if necessary, other diol esters) in the presence of a catalyst. Furthermore, solid-state polymerization can be carried out as needed to increase the molecular weight or reduce low-molecular-weight components.

[0077] The method for forming the thus obtained cellulose-based resin, methyl methacrylate-based resin, polyethylene terephthalate-based resin, etc. into a protective film to be adhered to a polarizing film can be selected appropriately depending on the resin, and is not particularly limited. For example, a solvent casting method in which a resin dissolved in a solvent is cast onto a metal band or drum and the solvent is dried and removed to obtain a film, or a melt extrusion method in which a resin is heated and kneaded above its melting temperature, extruded through a die, and cooled to obtain a film, can be used. This melt extrusion method may be the extrusion of a single layer film or the co-extrusion of a multilayer film.

[0078] The resin material constituting the protective film may contain appropriate additives as long as the transparency is not impaired. Examples of additives include antioxidants, UV absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents, antiblocking agents, retardation reducing agents, stabilizers, processing aids, plasticizers, impact resistance aids, matting agents, antibacterial agents, and antifungal agents. One or more of these additives may be used, or multiple types may be used in combination.

[0079] The thickness of the protective film is not particularly limited, but can be, for example, 5 μm or more, optionally 10 μm or more, optionally 20 μm or more, or optionally 30 μm or more, and is usually 120 μm or less, optionally 110 μm or less, optionally 100 μm or less, or optionally 900 μm or less. The protective film usually has a single-layer structure, but may have a multi-layer structure of two or more layers.

[0080] The protective film may be provided with a functional layer. Examples of the functional layer include a hard coat layer, an antiglare layer, an antireflection layer, and an antistatic layer. <Adhesive layer> To laminate the first polarizer 31 and the first protective film 32, and the first polarizer 31 and the retardation layer 40, an adhesive layer formed using a known adhesive or a pressure-sensitive adhesive layer formed using a known pressure-sensitive adhesive can be used.

[0081] Examples of the adhesive include a water-based adhesive, an active energy ray-curable adhesive, and a thermosetting adhesive, and preferably a water-based adhesive or an active energy ray-curable adhesive. The thickness of the attachment layer formed using the adhesive may be, for example, 0.01 μm or more, 0.1 μm or more, 0.5 μm or more, or 1 μm or more, and may be, for example, 20 μm or less, 15 μm or less, 10 μm or less, or 5 μm or less.

[0082] Examples of aqueous adhesives include adhesives made from aqueous polyvinyl alcohol resin solutions and aqueous two-component urethane emulsion adhesives. Among these, aqueous adhesives made from aqueous polyvinyl alcohol resin solutions are preferred. Examples of polyvinyl alcohol resins that can be used include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, a homopolymer of vinyl acetate, polyvinyl alcohol copolymers obtained by saponifying copolymers of vinyl acetate with other copolymerizable monomers, and modified polyvinyl alcohol polymers in which the hydroxyl groups of these copolymers are partially modified. The aqueous adhesives may contain crosslinkers such as aldehyde compounds (e.g., glyoxal), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

[0083] When a water-based adhesive is used as the adhesive, it is preferable to carry out a drying step to remove water contained in the water-based adhesive after laminating it with the film to be laminated. After the drying step, a curing step may be carried out, for example, in which the adhesive is cured at a temperature of 20 to 45°C.

[0084] The active energy ray-curable adhesive is an adhesive containing a curable compound that cures upon irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet-curable adhesive. The curable compound can be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of the cationically polymerizable curable compound include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (compounds having one or more oxetane rings in the molecule), and combinations thereof. Examples of the radically polymerizable curable compound include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having radically polymerizable double bonds, and combinations thereof. A cationically polymerizable curable compound and a radically polymerizable curable compound may be used in combination. An active energy ray-curable adhesive usually further contains a cationic polymerization initiator and / or a radical polymerization initiator to initiate the curing reaction of the curable compound.

[0085] A pressure-sensitive adhesive exhibits adhesive properties when attached to an adherend itself, and is known as a pressure-sensitive adhesive. The pressure-sensitive adhesive can be composed of a pressure-sensitive adhesive composition whose main component is a resin such as a (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin. Among these, a pressure-sensitive adhesive composition whose base polymer is a (meth)acrylic resin, which is excellent in transparency, weather resistance, heat resistance, etc., is preferred. The pressure-sensitive adhesive may be an active energy ray-curable or thermosetting type. The thickness of the attachment layer formed using the pressure-sensitive adhesive is usually 3 μm or more and 30 μm or less, and preferably 3 μm or more and 25 μm or less.

[0086] The (meth)acrylic resin (base polymer) contained in the pressure-sensitive adhesive composition is preferably a polymer or copolymer containing one or more (meth)acrylic acid esters as monomers, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. A polar monomer is preferably copolymerized into the base polymer. Examples of polar monomers include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, or an epoxy group, such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0087] The pressure-sensitive adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. Examples of crosslinking agents include divalent or higher metal ions that form metal carboxylates with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; polyepoxy compounds or polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Among these, polyisocyanate compounds are preferred.

[0088] When a water-based adhesive is used, the moisture permeability of at least one of the first protective film 32 and the retardation layer 40 must be 200 g / m 2 It is preferable to use one that is 24 hours or longer.

[0089] (Adhesive layer) As shown in FIG. 1(a), the first polarizing plate 10 may have an adhesive layer 35 for attaching the first polarizing plate 10 to a display element of a liquid crystal display device or the like. The adhesive layer 35 is preferably provided on the side of the retardation layer 40 of the first polarizing plate 10 opposite the first polarizer 31 side. The adhesive layer 35 can be formed using an adhesive. Examples of the adhesive include adhesives used to form the above-mentioned attachment layer. The thickness of the adhesive layer 35 is not particularly limited, but is usually 3 μm or more and 50 μm or less, preferably 5 μm or more and 40 μm or less, and may be 10 μm or more and 30 μm or less.

[0090] (Release film) The first polarizing plate 10 may have a release film that can be peeled off from the pressure-sensitive adhesive layer 35. The release film is used to cover and protect the surface of the pressure-sensitive adhesive layer 35 or to support the pressure-sensitive adhesive layer 35. Examples of the release film include a film in which a release treatment such as silicone treatment has been applied to the surface of the base resin film facing the pressure-sensitive adhesive layer 35. Examples of resin materials that constitute the base resin film include films formed using the resin materials described above for the base film. The base resin film may have a single-layer structure or a multi-layer structure of two or more layers.

[0091] (Polarizing Plate Manufacturing Method) The method for producing the first polarizing plate 10 is not particularly limited, and a known method can be used. For example, a first protective film 32 is laminated on one surface of a first polarizer 31 using a water-based adhesive, a retardation layer 40 is laminated on the other surface of the first polarizer 31 using a water-based adhesive, and a drying process is performed to remove water from the water-based adhesive to produce a laminate of the first polarizing plate 10. Thereafter, a pressure-sensitive adhesive layer 35 is laminated on the retardation layer 40 side of the laminate, thereby obtaining a first polarizing plate 10 with the pressure-sensitive adhesive layer.

[0092] To improve adhesion between the first protective film 32, first polarizer 31, retardation layer 40, functional layer, and other layers constituting the first polarizing plate 10, a surface activation treatment may be applied to the bonding surfaces of these films and layers. Examples of surface activation treatments include dry treatments such as corona treatment, plasma treatment, discharge treatment (e.g., glow discharge treatment), flame treatment, ozone treatment, UV ozone treatment, and ionizing actinic ray treatment (e.g., ultraviolet treatment, electron beam treatment), and wet treatments such as ultrasonic treatment using a solvent such as water or acetone, saponification treatment, and anchor coating treatment. These surface activation treatments may be performed alone or in combination of two or more.

[0093] <Second polarizing plate> The second polarizing plate 20 has a second polarizer 51 and a pair of protective films (hereinafter also referred to as second protective films 52) laminated on both sides of the second polarizer 51. Of the pair of second protective films 52, the second protective film 52 on the liquid crystal cell side is also referred to as one second protective film 52a, and the second protective film 52 on the other side is also referred to as the other second protective film 52b. One second protective film 52a is disposed between the liquid crystal cell 60 and the second polarizer 51.

[0094] [Second polarizer] The second polarizer 51 can be the same as the first polarizer 31. The second polarizer 51 also preferably has a cross transmittance of 0.05% or less at a wavelength of 410 nm, and may be 0.03% or less, or may be 0.01% or less.

[0095] Of the pair of second protective films 52, one second protective film 52a satisfies the following formulas (4) to (6). 0nm≦Re

[0550] ≦5nm (4) -5nm≦Rth

[0550] ≦5nm (5) -30nm≦Rth

[0450] ≦-1.0nm (6) When the second protective film 52a satisfies the above formulas (4) to (6), the viewing angle compensation effect of the retardation layer 40 can be further improved, and for example, the contrast at a viewing angle of an azimuth angle θ of 42.4° and an elevation angle φ of 23.4° of the liquid crystal panel can be further improved.

[0096] There are no particular limitations on the method for controlling the thickness of the second protective film 52a within the numerical ranges of the above formulas (4) to (6). The second protective film 52 may have a single layer structure or a multi-layer structure of two or more layers. Although there are no particular limitations on the materials, it can also be made by combining materials with different wavelength dispersion properties and different intrinsic birefringence.

[0097] For example, an example of a single-layer structure is a method in which a retardation adjusting agent with large wavelength dispersion is added to a film formed by a solvent casting method using a material with small wavelength dispersion and positive intrinsic birefringence, and the amount added is adjusted to satisfy formula (5).

[0098] Another method is to biaxially stretch a copolymer having a polymer unit with positive intrinsic birefringence and small wavelength dispersion and a polymer unit with negative intrinsic birefringence and high wavelength dispersion. In a two-layer film, a layer with a small wavelength dispersion and a positive Rth

[0550] is laminated with a layer with a large wavelength dispersion and a negative Rth

[0550] . In this case, each layer may be a coating layer, a cast film layer, or a combination of both. A liquid crystal alignment fixing layer or a cured layer may also be included.

[0099] The Re

[0550] of the second protective film 52a may be 3 nm or less, or may be 1 nm or less. The Rth

[0550] of the second protective film 52a may be 3 nm or less, or may be 0 nm or less. The Rth

[0450] of the second protective film 52a may be -5 nm or less, or may be -10 nm or less.

[0100] The second protective film 52b used in the second polarizing plate can be the same as the first protective film 32. The adhesives and pressure-sensitive adhesives for bonding the layers and the manufacturing method of the polarizing plate can also be the same as those for the first polarizing plate 10.

[0101] [LCD panel] The liquid crystal display panel of the present invention can be produced by placing a first polarizer 10 on one side of an IPS-mode liquid crystal cell and a second polarizer 20 on the other side. The IPS-mode liquid crystal cell has a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field. The liquid crystal display panel of the present invention can be used in either E mode or O mode. In either mode, the initial alignment direction of the liquid crystal cell and the absorption axis direction of the second polarizer 51 are arranged parallel to each other.

[0102] As shown in FIG. 2, the first polarizer 31 and the second polarizer 51 are disposed so that the direction of their absorption axes (see arrows) is perpendicular to that of the second polarizer 51. A brightness enhancement film may be provided between the liquid crystal panel and the light source, and the brightness enhancement film may be provided integrally with the polarizing plate on the light source side. [Example]

[0103] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, parts and % representing the content or amount used are based on mass unless otherwise specified. Furthermore, angles are positive in the counterclockwise direction.

[0104] <Preparing the protective film> The following protective films were prepared: Protective film E1: Saponified triacetyl cellulose film with a hard coat layer (manufactured by Toppan Printing Co., Ltd., product name "40FJCHCN-LMP", triacetyl cellulose film thickness: 40 μm, hard coat layer thickness: 7 μm).

[0105] Protective film E2: A laminated retardation film comprising a liquid crystal layer and a cycloolefin-based polymer film as described in paragraph

[0147] of WO 2022 / 158482. The liquid crystal layer corresponds to the positive C plate 42. The cycloolefin-based polymer film corresponds to the positive A plate 41.

[0106] The values ​​of Re

[0480] and Re

[0590] of protective film E2 were 123.3 nm and 122.0 nm, and Re

[0480] / Re

[0590] was 1.01. Protective film E2 satisfied the formulas (1) to (3).

[0107] <Preparation of protective film> (Protective film A) The protective film A of this example has a three-layer structure of a cellulose acylate film / an alignment film / a layer for fixing vertical alignment of rod-like liquid crystals.

[0108] A commercially available cellulose acylate film TD80UL (manufactured by Fujifilm Corporation: film thickness 80 μm) was immersed in a 1.5 mol / L NaOH aqueous solution (saponification solution) maintained at 55°C for 2 minutes, and then washed with water. The film was then immersed in a 0.05 mol / L sulfuric acid aqueous solution at 25°C for 30 seconds, and then passed through a water washing bath under running water for 30 seconds to neutralize the film. The film was then drained three times with an air knife to remove the water, and then allowed to dry in a drying zone at 70°C for 15 seconds to produce a saponified film.

[0109] Next, referring to paragraphs

[0320] to

[0328] of JP-A 2007-155972, a PVA-based alignment film was formed on which an optically anisotropic layer in which rod-like liquid crystals were vertically aligned was formed. (Preparation of First Optically Anisotropic Layer) An alignment film coating solution having the following composition was continuously applied to one side of the cellulose acylate film prepared as above using a #14 wire bar. The coating was dried with hot air at 60°C for 60 seconds and then with hot air at 100°C for 120 seconds to form an alignment film.

[0110] Composition of alignment film coating solution -------------------------- 10 parts by mass of the following modified polyvinyl alcohol: Water: 371 parts by mass Methanol: 119 parts by mass Glutaraldehyde: 0.5 parts by mass --------------------------

[0111] [ka]

[0112] A coating solution containing a rod-shaped liquid crystal compound of the following composition was applied to the above-prepared alignment film, and the film thickness was adjusted so that Rth

[0550] was -55 nm. The solvent was evaporated by successive heating processes from room temperature to 80°C, and the film was then heated at 80°C for 90 seconds to align the rod-shaped liquid crystal compound. The film temperature was then maintained at 60°C, and the alignment of the liquid crystal compound was fixed by UV irradiation to form an optically anisotropic layer.

[0113] Composition of coating solution containing rod-shaped liquid crystal compound ---------------------------------- The following rod-shaped liquid crystal compound (I): 100 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba-Geigy): 3 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.): 1 part by mass 0.4 parts by mass of the following fluorine-based polymer: 1 part by mass of the following pyridinium salt: Methyl ethyl ketone: 172 parts by mass ----------------------------------

[0114] [ka]

[0115] [ka]

[0116] [ka]

[0117] It was confirmed that an optically anisotropic layer was formed in which the rod-like liquid crystal molecules were aligned substantially perpendicular to the film surface. Table 2 shows the Rth at wavelengths of 450 nm and 550 nm, and the Re at a wavelength of 550 nm for Protective Film A.

[0118] (Protective film B) Protective film B was prepared in the same manner as protective film A, except that the thickness of the cellulose acylate film was set to 40 μm and the thickness of the rod-like liquid crystal vertical alignment fixing layer was adjusted.

[0119] (Protective film C) A protective film C was prepared in the same manner as the protective film A, except that the thickness of the cellulose acylate film was set to 20 μm and the thickness of the rod-like liquid crystal vertical alignment fixing layer was adjusted.

[0120] (Protective film D) An acrylic resin film (manufactured by Toyo Kohan Co., Ltd., product name "HX-40NE") having a thickness of 40 μm was used.

[0121] <Preparation of polarizer> (Production Example 1: Production of Polarizer (1)) A 30 μm-thick polyvinyl alcohol resin film was immersed in pure water at 21.5°C for 79 seconds. It was then immersed for 151 seconds in a 23°C aqueous solution containing 1.0 mM iodine and having a potassium iodide / boric acid / water mass ratio of 2 / 2 / 100. It was then immersed for 76 seconds in a 62.0°C aqueous solution containing 2.5 / 4 / 100 potassium iodide / boric acid / water mass ratio. It was then immersed for 11 seconds in a 45°C aqueous solution containing 3 / 5.5 / 100 potassium iodide / boric acid / water mass ratio. It was then dried at 38°C to obtain a 12 μm-thick polarizer 1 in which iodine was adsorbed and aligned in the polyvinyl alcohol. Stretching was mainly performed in the dyeing step and the first crosslinking step, with a total stretching ratio of 5.85. The polarizer (1) had a crossed transmittance of 0.002% at a wavelength of 410 nm. The thickness of the obtained polarizer was measured using a digital micrometer "MH-15M" manufactured by Nikon Corporation.

[0122] (Production Example 2: Preparation of Polarizer (2)) A 30 μm-thick polyvinyl alcohol-based resin film was immersed in pure water at 21.5°C for 79 seconds. It was then immersed for 151 seconds in a 23°C aqueous solution containing 1.0 mM iodine and having a potassium iodide / boric acid / water mass ratio of 2 / 2 / 100. It was then immersed for 76 seconds in a 62.0°C aqueous solution containing 2.5 / 4 / 100 potassium iodide / boric acid / water mass ratio. It was then immersed for 11 seconds in a 45°C aqueous solution containing 0.5 / 5.5 / 100 potassium iodide / boric acid / water mass ratio. It was then dried at 38°C to obtain a 12 μm-thick polarizer 2 in which iodine was adsorbed and aligned in the polyvinyl alcohol. Stretching was mainly performed in the dyeing step and the first crosslinking step, with a total stretch ratio of 5.85. The polarizer (2) had a crossed transmittance of 0.060% at a wavelength of 410 nm. The thickness of the polarizer 1 and the like was measured using a digital micrometer "MH-15M" manufactured by Nikon Corporation.

[0123] <Preparation of Adhesive Composition> (Production Example 3: Preparation of Adhesive Composition (1)) 50 g of modified polyvinyl alcohol resin containing acetoacetyl groups (Gohsenex Z-410, manufactured by Mitsubishi Chemical Corporation) was dissolved in 950 g of pure water, heated at 90°C for 2 hours, and then cooled to room temperature to obtain an acetoacetyl group-modified polyvinyl alcohol resin solution.

[0124] To the obtained acetoacetyl group-modified polyvinyl alcohol resin solution, a 40 mass % glyoxal solution, maleic acid, and pure water were added in amounts shown in Table 1 below to prepare adhesive composition (1). Note that Table 1 indicates the parts by mass of each component per 100 parts by mass of the adhesive composition.

[0125] [Table 1]

[0126] <Preparation of polarizing plate> (Production Example 4: Production of second polarizing plate 20-1) The surface of the protective film E1 without the hard coat layer was laminated on one surface of the polarizer (1) produced in Production Example 1 via the adhesive composition (1) prepared in Production Example 3. The cellulose acylate film surface of the protective film A was laminated on the other surface of the polarizer (1) via the adhesive composition (1) prepared in Production Example 3 using a roll laminator. The resulting film was then dried at 75°C for 8 minutes to obtain a polarizing plate (20-1). The adhesive layer formed of the adhesive composition (1) had a thickness of 80 nm after drying. The protective film A corresponds to one of the second protective films 52a. The protective film E1 corresponds to the other of the second protective films 52b. The polarizers (1) and (2) correspond to the second polarizer 51.

[0127] (Production Example 5: Preparation of second polarizing plates (20-2), (20-3), and (20-5)) Second polarizing plates (20-2), (20-3), and (20-5) were obtained in the same manner as the second polarizing plate (20-1), except that protective films B to D were used instead of protective film A.

[0128] (Production Example 6: Production of second polarizing plate (20-4)) The second polarizing plate (20-4) was obtained in the same manner as the second polarizing plate (20-2), except that the polarizer (2) was used instead of the polarizer (1). The second polarizing plates (20-1) to (20-5) correspond to the second polarizing plate 20.

[0129] The structures of the second polarizing plates (20-1) to (20-5) are shown in Table 2. In Table 2, the adhesive composition (1) is omitted.

[0130] [Table 2]

[0131] The physical properties of the polarizing plates (20-1) to (20-5) were measured by the following methods. <Measurement of in-plane retardation value and thickness direction retardation value> The in-plane retardation value (Re) and thickness direction retardation value (Rth) at each wavelength were measured at a temperature of 23°C using a retardation meter "KOBRA (registered trademark)-WPR" manufactured by Oji Scientific Instruments Co., Ltd., which is based on the parallel Nicol rotation method, to examine the wavelength dispersion.

[0132] <Measurement of crossed transmittance of polarizer at wavelength of 410 nm> The crossed transmittance of the polarizers (1) and (2) at a wavelength of 410 nm was measured using a spectrophotometer equipped with an integrating sphere ("V7100" manufactured by JASCO Corporation, 2-degree field of view; C light source).

[0133] (Production Example 7: Production of first polarizing plate (10-1)) The surface of the protective film E1 without the hard coat layer was laminated on one side (one side) of the polarizer (1) produced in Production Example 1 via the adhesive composition (1) prepared in Production Example 3. The protective film E2 was laminated on the other side of the polarizer (1) via the adhesive composition (1) prepared in Production Example 3, and the two were bonded using a roll laminator. The liquid crystal layer of E2 was positioned on the polarizer side, and the slow axis of the positive A plate 41 and the absorption axis of the first polarizer 31 were substantially parallel. The film was then dried at 75°C for 8 minutes to obtain a first polarizing plate (10-1). The adhesive layer made of the adhesive composition (1) had a thickness of 80 nm after drying. The protective film E1 corresponds to one of the first protective films 32. The protective film E2 corresponds to the retardation layer 40. The polarizer (1) corresponds to the first polarizer 31. The first polarizing plate (10-1) corresponds to the first polarizing plate 10.

[0134] Table 3 shows the structure of the polarizing plate (10-1).

[0135] [Table 3]

[0136] <Evaluation of polarizing plate sets> A Pioneer Corporation car navigation system "AVIC-RZ120" was disassembled, and the upper and lower polarizing plates of the liquid crystal cell (60-1) were peeled off. This liquid crystal cell (60-1) was an IPS-type liquid crystal cell. The polarizing plates obtained in Production Examples 4 to 7 were prepared instead of the original polarizing plates. The protective film E2 side of the first polarizing plate 10 and the second protective films A to D sides of the second polarizing plate 20 were attached to the liquid crystal cell (60-1) via a pressure-sensitive adhesive. That is, the first polarizing plate (10-1) was attached to the viewing side, and the second polarizing plates (20-1) to (20-5) were attached to the TFT side.

[0137] <Evaluation of viewing angle contrast> After reassembling the car navigation system, the backlight was turned on and the contrast at an azimuth angle of θ42.4° / elevation angle of φ23.4° was measured using an ELDIM LCD viewing angle measuring device, "EZ CONTRAST 160R." The viewing angle contrast was evaluated according to the following criteria. The results are shown in Table 4.

[0138] The polarizing plate set of the present invention can also improve contrast at other predetermined viewing angles, for example, an azimuth angle θ of 42.4° and an elevation angle φ of 156.6°. Viewing angle contrast evaluation criteria 2A (particularly excellent): Viewing angle contrast ratio of 660 or more A (Excellent): Viewing angle contrast is 640 or more and less than 660 B (Good): Viewing angle contrast is 620 or more and less than 640 C (Acceptable): Viewing angle contrast is 600 or more and less than 620 D (unacceptable): Viewing angle contrast is less than 600

[0139] [Table 4] [Explanation of symbols]

[0140] 10...First polarizing plate 20...Second polarizing plate 31...First polarizer 32...First protective film 35...Adhesive layer 40...Retardation layer 41...Positive A plate 42...Positive C-plate 51...Second polarizer 52...Second protective film 52a...One second protective film 52b...the other second protective film

Claims

1. A set of polarizing plates to be attached to both sides of a liquid crystal cell having a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field, a first polarizing plate disposed on one surface of the liquid crystal cell and a second polarizing plate disposed on the other surface of the liquid crystal cell; the first polarizing plate has a first polarizer and a retardation layer, the retardation layer is disposed between the liquid crystal cell and the first polarizer, The retardation layer satisfies the following formulas (1) to (3), ny[590]<nz[590]<nx[590] (1) 0.8≦Re[480] / Re[590]≦1.2 (2) 100 nm≦Re[590]≦150 nm (3) the second polarizing plate includes a second polarizer and a protective film, the protective film is disposed between the liquid crystal cell and the second polarizer, The protective film satisfies the following formulas (4) to (6), 0 nm≦Re[550]≦5 nm (4) −5 nm≦Rth[550]≦5 nm (5) -30nm≦Rth[450]≦-1.0nm (6) A set of polarizing plates, wherein the slow axis of the retardation layer is substantially parallel to or substantially perpendicular to the absorption axis of the first polarizer.

2. 2. The set of polarizing plates according to claim 1, wherein the crossed transmittance of the first polarizer and the second polarizer at a wavelength of 410 nm is 0.05% or less.

3. 2. The set of polarizing plates according to claim 1, wherein the retardation layer comprises a positive A plate and a positive C plate.

4. a liquid crystal cell having a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field; a first polarizing plate disposed on one surface of the liquid crystal cell; a second polarizing plate disposed on the other surface of the liquid crystal cell, the first polarizing plate has a first polarizer and a retardation layer, the retardation layer is disposed between the liquid crystal cell and the first polarizer, The retardation layer satisfies the following formulas (1) to (3), ny[590]<nz[590]<nx[590] (1) 0.8≦Re[480] / Re[590]≦1.2 (2) 100 nm≦Re[590]≦150 nm (3) the second polarizing plate includes a second polarizer and a protective film, the protective film is disposed between the liquid crystal cell and the second polarizer, The protective film satisfies the following formulas (4) to (6), 0 nm≦Re[550]≦5 nm (4) −5 nm≦Rth[550]≦5 nm (5) -30nm≦Rth[450]≦-1.0nm (6) a slow axis of the retardation layer is substantially parallel to or substantially perpendicular to an absorption axis of the first polarizer, The liquid crystal panel, wherein the absorption axis of the first polarizer and the absorption axis of the second polarizer are substantially perpendicular to each other.

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