JP2006268018A - Polarizing element, liquid crystal panel, liquid crystal television, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing element capable of increasing a contrast ratio of a liquid crystal display device in an oblique direction and also decreasing a color shift quantity in an oblique direction. <P>SOLUTION: The polarizing element of the present invention is equipped with a polarizer, and a negative C plate, a positive A plate, and a positive C plate on one side of the polarizer, and characterized in that the positive A late is arranged between the polarizer and positive C plate while having its slow axis substantially orthogonally to an axis of absorption of the polarizer and Rth<SB>PC</SB>[590] of the positive C plate is ≤-60 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polarizing element, and a liquid crystal panel, a liquid crystal television and a liquid crystal display device using the polarizing element.

  Liquid crystal display devices are attracting attention for their features such as thinness, light weight, and low power consumption. Mobile devices such as mobile phones and watches; OA devices such as personal computer monitors and laptop computers; and home appliances such as video cameras and liquid crystal televisions. Widely popular. This is because technical innovations are overcoming the drawbacks of changing display characteristics depending on the angle at which the screen is viewed and not operating at high or very low temperatures. However, the properties required for each application have changed as the applications are diverse. For example, in a conventional liquid crystal display device, it has been considered that the viewing angle characteristic should have a contrast ratio of white / black display of about 10 in an oblique direction. This definition is derived from the contrast ratio of black ink printed on white paper such as newspapers and magazines. However, in stationary large color television applications, several people see the screen at the same time, so a display that can be seen well from different viewing angles is required. Specifically, for example, the contrast ratio of white / black display needs to be 20 or more even in an oblique direction. In addition, since the faint coloring in black display makes the color display clear, it is important to make the background color pure black. In addition, when the display becomes large, the person who looks at the screen does not move, but when viewing the four corners of the screen, it is the same as viewing from a different viewing angle direction. It is also important that there is no unevenness and the display is uniform. If such a technical problem is not improved in a large color television application, a person watching the screen will feel uncomfortable or tired.

Conventionally, various retardation films are used in liquid crystal display devices. For example, a method of arranging a plurality of retardation films on one side of an in-plane switching (IPS) type liquid crystal cell to improve coloring of an image (also referred to as oblique color shift) that changes with the viewing angle. It is disclosed (for example, see Patent Document 1). However, with such a technique, the contrast ratio in the oblique direction and the color shift amount in the oblique direction are not sufficiently improved, and the display characteristics of the obtained liquid crystal display device satisfy the level required for large color television applications. Not.
JP 11-133408 A

  The present invention has been made to solve such a problem, and an object of the present invention is to reduce the light leakage in the black display of the liquid crystal display device, and as a result, increase the contrast ratio in the oblique direction of the liquid crystal display device. A polarizing element capable of reducing the amount of color shift in a direction is provided.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the polarizing element shown below, and have completed the present invention.

The polarizing element of the present invention includes a polarizer and a negative C plate, a positive A plate, and a positive C plate disposed on one side of the polarizer, and the slow axis of the positive A plate is the polarizer. Is disposed between the polarizer and the positive C plate so as to be substantially orthogonal to the absorption axis of the positive C plate, and Rth _PC [590] of the positive C plate is −60 nm or less.

In a preferred embodiment, Rth _NC [590] of the negative C plate is 30 nm to 200 nm.

In a preferred embodiment, the sum of Rth _NC [590] of the negative C plate and Rth _PC [590] of the positive C plate is −150 nm to −30 nm.

  In a preferred embodiment, the negative C plate is a polymer film mainly composed of at least one thermoplastic resin selected from a cellulose resin, a polyamideimide resin, a polyether ether ketone resin, and a polyimide resin. including.

In a preferred embodiment, Re _PA [590] of the positive A plate is 60 nm to 180 nm.

  In a preferred embodiment, the positive A plate includes a stretched polymer film containing a styrenic resin.

  In a preferred embodiment, the positive C plate includes a solidified layer or a cured layer of a liquid crystalline composition containing a liquid crystal compound that is homeotropically aligned.

  In a preferred embodiment, the liquid crystal composition includes a liquid crystal compound having at least one polymerizable functional group in a part of the molecular structure.

  In a preferred embodiment, the solidified layer or the cured layer of the liquid crystalline composition containing the homeotropically aligned liquid crystal compound has a thickness of 0.6 μm to 20 μm.

  According to another aspect of the present invention, a liquid crystal panel is provided. This liquid crystal panel includes the polarizing element described above and a liquid crystal cell.

  In a preferred embodiment, the liquid crystal cell includes a liquid crystal layer including a nematic liquid crystal that is homogeneously aligned in the absence of an electric field.

  According to another aspect of the present invention, a liquid crystal television is provided. The liquid crystal television includes the liquid crystal panel.

  According to another aspect of the present invention, a liquid crystal display device is provided. The liquid crystal display device includes the liquid crystal panel.

  By disposing the polarizing element of the present invention at least on one side of the liquid crystal display device, the contrast ratio in the oblique direction of the liquid crystal display device can be increased, the color shift amount in the oblique direction can be reduced, and excellent display characteristics can be obtained. .

<< A. Outline of polarizing element >>
1A to 1C are schematic cross-sectional views of a polarizing element according to a preferred embodiment of the present invention. 2 (a) to 2 (c) are schematic perspective views of the polarizing elements of FIGS. 1 (a) to 1 (c), respectively. It should be noted that, for the sake of easy understanding, the ratios of the vertical, horizontal, and thickness of the constituent members in FIGS. 1 and 2 are described differently from actual ones. Each of these polarizing elements (10, 11, and 12) includes a polarizer 20, and a negative C plate 30, a positive A plate 40, and a positive C plate 50 disposed on one side of the polarizer 20. The positive A plate 40 is disposed between the polarizer 20 and the positive C plate 50 so that the slow axis thereof is substantially perpendicular to the absorption axis of the polarizer 20. Rth _PC [590] of the positive C plate 50 is −60 nm or less: where Rth [590] is a retardation value in the thickness direction measured with light having a wavelength of 590 nm at 23 ° C. Practically, an optional protective layer (not shown) can be disposed outside the polarizer 20 (on the side where the negative C plate 30 or the like is not disposed).

  The polarizing element 10 shown in FIG. 1A includes a polarizer 20, a negative C plate 30, a positive A plate 40, and a positive C plate 50 in this order. The polarizing element 11 shown in FIG. 1B includes a polarizer 20, a positive A plate 40, a positive C plate 50, and a negative C plate 30 in this order. The polarizing element 12 shown in FIG. 1C includes a polarizer 20, a positive A plate 40, a negative C plate 30, and a positive C plate 50 in this order. 1A to 1C, the positive A plate 40 has a polarizer such that the slow axis of the positive A plate 40 is substantially perpendicular to the absorption axis of the polarizer 20. 20 and the positive C plate 50. Thus, by using a specific optical element in a specific positional relationship, the function of each optical element is exhibited synergistically. For example, when the polarizing element of the present invention is disposed on one side of the liquid crystal cell, the contrast ratio in the oblique direction of the liquid crystal display device can be increased and the color shift amount in the oblique direction can be reduced. The polarizing element of the present invention is not limited to the illustrated examples as long as the object of the present invention is satisfied. For example, an adhesive layer (typically, an adhesive layer or an anchor coat layer) or another optical member (preferably an isotropic film) is disposed between the illustrated optical members. May be. Hereinafter, details of each member constituting the polarizing element of the present invention will be described.

<< B. Polarizer
In this specification, a polarizer means a film that can be converted from natural light or polarized light into arbitrary polarized light. Any appropriate polarizer may be adopted as the polarizer used in the present invention, but a polarizer that converts natural light or polarized light into linearly polarized light is preferably used.

  Any appropriate thickness can be adopted as the thickness of the polarizer. The thickness of the polarizer is typically 5 μm to 80 μm, preferably 10 μm to 50 μm, and more preferably 20 μm to 40 μm. If it is said range, what is excellent in an optical characteristic and mechanical strength can be obtained.

<< B-1. Optical properties of polarizers >>
The transmittance of the polarizer measured at 23 ° C. at a wavelength of 440 nm (also referred to as single transmittance) is preferably 41% or more, more preferably 43% or more. Note that the theoretical upper limit of the single transmittance is 50%. The degree of polarization is preferably 99.8% or more, and more preferably 99.9 or more. The theoretical upper limit of the degree of polarization is 100%. If it is said range, when it uses for a liquid crystal display device, the contrast ratio of a front direction can be made high.

The single transmittance and the degree of polarization can be measured using a spectrophotometer [product name “DOT-3” manufactured by Murakami Color Research Laboratory Co., Ltd.]. As a specific method for measuring the degree of polarization, the parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ) of the polarizer are measured, and the formula: degree of polarization (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100. The parallel transmittance (H ₀ ) is a value of the transmittance of a parallel laminated polarizer prepared by superposing two identical polarizers so that their absorption axes are parallel to each other. The orthogonal transmittance (H ₉₀ ) is a value of the transmittance of an orthogonal laminated polarizer produced by superposing two identical polarizers so that their absorption axes are orthogonal to each other. Note that these transmittances are Y values obtained by performing visibility correction using a two-degree field of view (C light source) of JlS Z 8701: 1982.

<< B-2. Means for arranging polarizers >>
Referring to FIG. 2, any appropriate method may be adopted as a method of arranging the polarizer 20 depending on the purpose. Preferably, the polarizer 20 is provided with an adhesive layer (not shown) on the surface facing the liquid crystal cell, and is attached to the surface of the negative C plate 30 or the positive A plate 40. By doing so, the contrast can be increased when used in a liquid crystal display device. In the present specification, the “adhesive layer” means that the surfaces of adjacent optical elements and polarizers are joined and integrated with an adhesive force and an adhesive time that do not adversely affect practical use. If there is, there is no particular limitation. Specific examples of the adhesive layer include an adhesive layer and an anchor coat layer. The adhesive layer may have a multilayer structure in which an anchor coat layer is formed on the surface of an adherend and an adhesive layer is formed thereon.

  The thickness of the adhesive layer can be determined as appropriate according to the purpose of use and adhesive strength. Preferably they are 0.1 micrometer-50 micrometers, More preferably, they are 0.5 micrometer-40 micrometers, Most preferably, they are 1 micrometer-30 micrometers. If it is said range, the optical element and polarizer to which it joins will not float or peel, and the adhesive force and adhesion time which do not have a bad influence on practical use can be obtained.

  As the material for forming the adhesive layer, an appropriate adhesive or anchor coating agent can be selected according to the type and purpose of the adherend. Specific examples of adhesives include solvent-based adhesives, emulsion-type adhesives, pressure-sensitive adhesives, rehumidifying adhesives, polycondensation-type adhesives, solventless adhesives, and film-like adhesives according to the classification by shape. Agents, hot melt adhesives, and the like. According to the classification by chemical structure, synthetic resin adhesives, rubber adhesives, and natural product adhesives can be mentioned. The adhesive includes a viscoelastic substance (also referred to as an adhesive) that exhibits an adhesive force that can be sensed by pressure contact at room temperature.

  The material for forming the adhesive layer is preferably a water-soluble adhesive when a polymer film containing a polyvinyl alcohol resin as a main component is used as a polarizer. More preferably, the water-soluble adhesive is mainly composed of a polyvinyl alcohol-based resin. A specific example is an adhesive [trade name “GOHSEIMER Z200” manufactured by Nippon Synthetic Chemical Co., Ltd.] mainly composed of a modified polyvinyl alcohol having an acetoacetyl group. These water-soluble adhesives may further contain a crosslinking agent. The types of cross-linking agents include amine compounds [Mitsubishi Gas Chemical Co., Ltd. trade name “metaxylene diamine”], aldehyde compounds [Nippon Synthetic Chemical Co., Ltd. trade name “Glyoxal”], methylol compounds [Dainippon Ink. Product name "Watersol"], an epoxy compound, an isocyanate compound, a polyvalent metal salt, etc. are mentioned.

<< B-3. Optical film used for polarizers >>
Although there is no restriction | limiting in particular as an optical film used for the said polarizer, For example, the stretched film of the polymer film which has iodine or a dichroic dye as a main component and contains polyvinyl alcohol-type resin; US Patent 5,523 An O-type polarizer obtained by aligning a liquid crystalline composition containing a dichroic material and a liquid crystalline compound in a certain direction as disclosed in US Pat. No. 863; and disclosed in US Pat. No. 6,049,428. And an E-type polarizer in which lyotropic liquid crystal is aligned in a certain direction.

  Preferably, the polarizer is a stretched film of a polymer film containing, as a main component, a polyvinyl alcohol-based resin containing iodine or a dichroic dye. This is because the degree of polarization is high and the contrast ratio in the front direction of the liquid crystal display device can be increased. The polymer film containing the polyvinyl alcohol resin as a main component is produced, for example, by the method described in JP 2000-315144 A [Example 1].

  As said polyvinyl alcohol-type resin, what saponified the vinyl ester-type polymer obtained by superposing | polymerizing a vinyl ester-type monomer and using the vinyl ester unit as the vinyl alcohol unit can be used. Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, and the like. Of these, vinyl acetate is preferable.

  Any appropriate average degree of polymerization may be adopted as the average degree of polymerization of the polyvinyl alcohol resin. The average degree of polymerization is preferably 1200 to 3600, more preferably 1600 to 3200, and most preferably 1800 to 3000. The average degree of polymerization of the polyvinyl alcohol resin can be measured by a method according to JIS K 6726: 1994.

  The saponification degree of the polyvinyl alcohol-based resin is preferably 90.0 to 99.9 mol%, more preferably 95.0 to 99.9 mol%, most preferably from the viewpoint of the durability of the polarizer. Preferably it is 98.0-99.9 mol%.

  The saponification degree indicates the proportion of units that are actually saponified to vinyl alcohol units among the units that can be converted to vinyl alcohol units by saponification. The saponification degree of the polyvinyl alcohol resin can be determined according to JIS K 6726: 1994.

  The polymer film mainly composed of the polyvinyl alcohol-based resin used in the present invention can preferably contain a polyhydric alcohol as a plasticizer. Examples of the polyhydric alcohol include ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane. These may be used alone or in combination of two or more. In the present invention, ethylene glycol or glycerin is preferably used from the viewpoint of stretchability, transparency, thermal stability, and the like.

  The amount of polyhydric alcohol used in the present invention is preferably 1 to 30 parts by weight, more preferably 3 to 25 parts by weight, and most preferably with respect to 100 parts by weight of the total solid content of the polyvinyl alcohol resin. Is 5 to 20 parts by weight. If it is said range, dyeability and stretchability can be improved further.

  The polymer film containing the polyvinyl alcohol resin as a main component can further contain a surfactant. The surfactant is used for the purpose of improving dyeability, stretchability and the like.

  Any appropriate type of surfactant can be adopted as the type of the surfactant, and specific examples include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. In the present invention, a nonionic surfactant is preferably used. Specific examples of the nonionic surfactant include lauric acid diethanolamide, coconut oil fatty acid diethanolamide, coconut oil fatty acid monoethanolamide, lauric acid monoisopropanolamide, oleic acid monoisopropanolamide, and the like. In the present invention, lauric acid diethanolamide is preferably used.

  The amount of the surfactant used is preferably more than 0 and 1 part by weight or less, more preferably 0.01 to 0.5 parts by weight, most preferably 100 parts by weight of the polyvinyl alcohol resin. Is 0.05 to 0.3 parts by weight. By setting it as the above range, dyeability and stretchability can be improved.

  Any appropriate dichroic material can be adopted as the dichroic material. Specific examples include iodine or a dichroic dye. In this specification, “dichroism” refers to optical anisotropy in which light absorption differs in two directions, ie, an optical axis direction and a direction perpendicular thereto.

  Examples of the dichroic dye include red BR, red LR, red R, pink LB, rubin BL, Bordeaux GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, and violet. B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First Orange S, First Black and the like can be mentioned.

  An example of a method for manufacturing a polarizer will be described with reference to FIG. FIG. 3 is a schematic view showing the concept of a typical production process of a polarizer used in the present invention. For example, a polymer film 301 mainly composed of a polyvinyl alcohol-based resin is drawn out from the feed-out unit 300, immersed in an iodine aqueous solution bath 310, and tensioned in the film longitudinal direction by rolls 311 and 312 having different speed ratios. While being subjected to swelling and dyeing processes. Next, it is immersed in a bath 320 of an aqueous solution containing boric acid and potassium iodide, and subjected to a crosslinking treatment while tension is applied in the longitudinal direction of the film with rolls 321 and 322 having different speed ratios. The film subjected to the crosslinking treatment is immersed in an aqueous solution bath 330 containing potassium iodide by rolls 331 and 332 and subjected to a water washing treatment. The water-washed film is dried by the drying means 340 so that the moisture content is adjusted and taken up by the take-up unit 360. The polarizer 350 can be obtained by stretching the polymer film containing the polyvinyl alcohol resin as a main component to 5 to 7 times the original length through these steps.

  Any appropriate moisture content can be adopted as the moisture content of the polarizer. Preferably, the moisture content is 5% to 40%, more preferably 10% to 30%, and most preferably 20% to 30%.

<< C. Negative C plate >>
In this specification, the “negative C plate” refers to a negative uniaxial optical element whose refractive index distribution satisfies nx = ny> nz. Ideally, a negative uniaxial optical element whose refractive index distribution satisfies nx = ny> nz has an optical axis in the normal direction. In the present specification, nx = ny includes not only the case where nx and ny are completely the same, but also the case where nx and ny are substantially the same. Here, “when nx and ny are substantially the same” means, for example, that the in-plane retardation value (Re [590]) measured with light having a wavelength of 590 nm at 23 ° C. is 10 nm or less. Including things. Re [590] will be described later. Here, nx is the refractive index in the slow axis direction, ny is the refractive index in the fast axis direction, and nz is the refractive index in the thickness direction. The slow axis is the direction in which the in-plane refractive index is maximized, and the fast axis is the direction perpendicular to the slow axis in the plane.

  Referring to FIGS. 1 and 2, the negative C plate 30 can be disposed at any location as long as it is between the polarizer 20 and the liquid crystal cell 100. Preferably, the negative C plate 30 is disposed between the polarizer 20 and the positive A plate 40 as shown in FIG. According to such an embodiment, the negative C plate 30 also serves as a protective layer on the liquid crystal cell side of the polarizer 20, and the polarizing element of the present invention is used in a liquid crystal display device in a high temperature and high humidity environment. However, the uniformity of the display screen can be maintained for a long time.

<< C-1. Optical characteristics of negative C plate >>
In this specification, Re [590] refers to an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C. Re [590] can be obtained by the formula: Re [590] = (nx−ny) × d.

The Re _NC [590] of the negative C plate used in the present invention is 10 nm or less, preferably 5 nm or less, more preferably 3 nm or less. The theoretical lower limit value of Re _NC [590] of the negative C plate is 0 nm.

  In this specification, Rth [590] refers to a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C. Rth [590] can be obtained by the formula: Rth [590] = (nx−nz) × d.

The Rth _NC [590] of the negative C plate used in the present invention is 20 nm or more, preferably 30 nm to 200 nm, and more preferably 30 nm to 160 nm. More specifically, referring to FIG. 2, when the polarizing element of the present invention is used in the embodiment of FIG. 2 (a), the Rth _NC [590] is preferably 30 nm to 160 nm, and more preferably Is 30 nm to 140 nm, particularly preferably 30 nm to 120 nm. When the polarizing element of the present invention is used in the embodiment of FIG. 2 (b) or (c), the Rth _NC [590] is preferably 50 nm to 200 nm, more preferably 50 nm to 160 nm, Preferably it is 50 nm-120 nm. By setting it as the above range, the function of each optical element is exhibited synergistically, the contrast ratio in the oblique direction of the liquid crystal display device can be increased, and the color shift amount in the oblique direction can be reduced.

In addition, Rth _NC [590] of the negative C plate has a sum (Rth _add ) of Rth _NC [590] of the negative C plate and Rth _PC [590] of the positive C plate of −150 nm to 10 nm. It is preferable to adjust the range. More preferably, it is -150 nm--30 nm, Most preferably, it is -130 nm--40 nm. More specifically, referring to FIG. 2, when the polarizing element of the present invention is used in the embodiment of FIG. 2A, the Rth _add is preferably −90 nm to −30 nm, particularly preferably. -80 nm to -40 nm. When the polarizing element of the present invention is used in the embodiment of FIG. 2 (b) or (c), the Rth _add is preferably −150 nm to −50 nm, and more preferably −130 nm to −70 nm. The Rth _PC [590] of the positive C plate will be described later in the section E-1.

Re [590] and Rth [590] can also be obtained by using a trade name “KOBRA21-ADH” manufactured by Oji Scientific Instruments. In-plane retardation value (Re) at a wavelength of 590 nm at 23 ° C., retardation value (R40) measured by tilting the slow axis as an inclination axis by 40 degrees, retardation film thickness (d), and retardation film Using the average refractive index (n0), nx, ny and nz can be obtained by computer numerical calculation from the following formulas (i) to (iii), and then Rth can be calculated by formula (iv). Here, φ and ny ′ are represented by the following equations (v) and (vi), respectively.
Re = (nx−ny) × d (i)
R40 = (nx−ny ′) × d / cos (φ) (ii)
(Nx + ny + nz) / 3 = n0 (iii)
Rth = (nx−nz) × d (iv)
φ = sin ⁻¹ [sin (40 °) / n0]
... (v)
ny ′ = ny × nz [ny ² × sin ² (φ) + nz ² × cos ² (φ)] ^1/2 (vi)

<< C-2. Means for placing negative C plate >>
Referring to FIG. 2, any appropriate method may be adopted as a method of arranging the negative C plate 30 depending on the purpose. Preferably, the negative C plate 30 is provided with adhesive layers (not shown) on both sides thereof. For example, when used in the embodiment of FIG. 2A, the negative C plate 30 is attached to the polarizer 20 and the positive A plate 40. Worn. In this way, by filling the gaps between the optical elements with the adhesive layer, the optical axes of the optical elements can be prevented from shifting when they are incorporated into a liquid crystal display device, or the optical elements can be rubbed and damaged. Can be prevented. Further, it is possible to reduce the adverse effects of reflection and refraction generated at the interface between the layers of each optical element, and to increase the contrast ratio in the front and oblique directions of the liquid crystal display device.

  The thickness of the adhesive layer can be determined as appropriate according to the purpose of use and adhesive strength. Preferably they are 0.1 micrometer-50 micrometers, More preferably, they are 0.5 micrometer-40 micrometers, Most preferably, they are 1 micrometer-30 micrometers. If it is said range, the optical element and polarizer to which it joins will not float or peel, and the adhesive force and adhesion time which do not have a bad influence on practical use can be obtained.

  As a material for forming the adhesive layer, for example, an appropriate material can be selected from those exemplified in the above section B-2. A material for forming an adhesive layer suitable for laminating optical elements is preferably acrylic in terms of excellent optical transparency, moderate wettability and adhesiveness, and excellent weather resistance and heat resistance. A pressure-sensitive adhesive (also referred to as an acrylic pressure-sensitive adhesive) having a base polymer as a base polymer and an isocyanate-based adhesive are used. Specific examples of the acrylic pressure-sensitive adhesive include optical double-sided tape, trade name “SK-2057” manufactured by Soken Chemical Co., Ltd. A specific example of the isocyanate-based adhesive is “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.

  In the negative C plate 30, when nx and ny are completely the same, no retardation value is generated in the plane, so that the slow axis is not detected, the absorption axis of the polarizer 20, and the positive A plate They can be arranged independently of the slow axis. Even if nx and ny are substantially the same, a slow axis may be detected if nx and ny are slightly different. In this case, the negative C plate 30 is preferably arranged so that its slow axis is substantially parallel to or substantially perpendicular to the absorption axis of the polarizer 20. In this specification, “substantially parallel” means that the angle formed by two directions (here, the angle formed by the slow axis of the negative C plate 30 and the absorption axis of the polarizer 20) is 0 °. Including the case of ± 2.0 °, preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °. Further, “substantially orthogonal” means that an angle formed by two directions (here, an angle formed by the slow axis of the negative C plate 30 and the absorption axis of the polarizer 20) is 90 ° ± 2.0 °. And is preferably 90 ° ± 1.0 °, more preferably 90 ° ± 0.5 °. As the degree of deviation from these angular ranges increases, the contrast ratio in the front and oblique directions tends to decrease when used in a liquid crystal display device.

<< C-3. Structure of negative C plate >>
The configuration (laminated structure) of the negative C plate is not particularly limited as long as it satisfies the optical characteristics described in the above section C-1. Specifically, the negative C plate may be a retardation film alone or a laminate composed of two or more retardation films. Preferably, the negative C plate is a single retardation film. This is because the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight are reduced, and the liquid crystal panel can be thinned. When the negative C plate is a laminate, an adhesive layer (for example, an adhesive layer or an anchor coat layer) may be included. When the laminate includes two or more retardation films, these retardation films may be the same or different. Details of the retardation film will be described later in the section C-4.

Rth [590] of the retardation film used for the negative C plate can be appropriately selected depending on the number of retardation films used. For example, when the negative C plate is composed of the retardation film alone, it is preferable that Rth [590] of the retardation film is equal to Rth [590] of the negative C plate. Therefore, it is preferable that the retardation value of the adhesive layer used when the negative C plate is laminated on the polarizer, the positive A plate, or the positive C plate is as small as possible. For example, when the negative C plate is a laminate including two or more retardation films, the sum of Rth [590] of each retardation film is Rth _NC [590] of the negative C plate. It is preferable to design to be equal. Specifically, when a negative C plate having a Rth _NC [590] of 60 nm is produced by laminating two retardation films, the Rth [590] of each retardation film may be 30 nm. it can. Alternatively, Rth [590] of one retardation film can be 10 nm, and Rth [590] of the other retardation film can be 50 nm. When two retardation films are laminated, it is preferable to arrange the retardation films so that the slow axes of the respective retardation films are orthogonal to each other. This is because Re [590] can be reduced. Here, for the sake of simplicity, only the case where the number of retardation films is two or less is shown, but it goes without saying that the present invention can also be applied to a laminate including three or more retardation films.

  The total thickness of the negative C plate is, for example, 1 μm to 200 μm, more preferably 2 μm to 150 μm, and most preferably 3 μm to 100 μm. By setting it as said range, the optical element excellent in optical uniformity can be obtained.

<< C-4. Retardation film used for negative C plate >>
The retardation film used for the negative C plate is not particularly limited, but a film that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, etc., and does not cause optical unevenness due to strain is preferably used. .

The absolute value (C [590] (m ² / N)) of the photoelastic coefficient of the retardation film is preferably 1 × 10 ⁻¹² to 200 × 10 ⁻¹² , more preferably 1 × 10 ⁻¹² to 50 × 10 ⁻¹² , most preferably 1 × 10 ⁻¹² to 30 × 10 ⁻¹² . The smaller the absolute value of the photoelastic coefficient, the smaller the deviation and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight when it is used in a liquid crystal display device. A device can be obtained.

  The transmittance of the retardation film measured with light having a wavelength of 590 nm at 23 ° C. is preferably 80% or more, more preferably 85% or more, and most preferably 90% or more. The negative C plate preferably has the same transmittance. The theoretical upper limit of the transmittance is 100%.

  The material for forming the retardation film is preferably a polymer film mainly composed of a thermoplastic resin. More preferably, it is a polymer film mainly composed of an amorphous polymer of a thermoplastic resin. Amorphous polymers have the advantage of excellent transparency. The polymer film containing the thermoplastic resin as a main component may or may not be stretched.

  An appropriate range of the thickness of the polymer film containing the thermoplastic resin as a main component can be selected according to the retardation value to be designed, the type of the thermoplastic resin to be used, and the like. Preferably they are 20 micrometers-120 micrometers, More preferably, they are 30 micrometers-100 micrometers. Within the above range, a retardation film excellent in mechanical strength and optical uniformity and satisfying the optical characteristics described in the above section C-1 can be obtained.

  Examples of the thermoplastic resin include polyolefin resins, cycloolefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, polymethyl methacrylate resins, polyvinyl acetate resins, and polyvinylidene chloride resins. General-purpose plastics: General-purpose engineering plastics such as polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins; polyphenylene sulfide resins, polysulfone resins, polyether sulfones Super resins such as resins, polyether ether ketone resins, polyarylate resins, liquid crystal polymers, polyamideimide resins, polyimide resins, polytetrafluoroethylene resins, etc. -Engineering plastic, and the like. Said thermoplastic resin is used individually or in combination of 2 or more types. The thermoplastic resin can be used after any appropriate polymer modification. Examples of the polymer modification include modifications such as copolymerization, crosslinking, molecular terminals, and stereoregularity.

  Preferably, the retardation film used for the negative C plate is mainly composed of at least one thermoplastic resin selected from a cellulose resin, a polyamideimide resin, a polyether ether ketone resin, and a polyimide resin. It is a polymer film. For example, when these thermoplastic resins are formed into a sheet by the solvent casting method, the molecules are spontaneously oriented in the process of evaporation of the solvent, so that no special secondary processing such as stretching is required. In addition, a retardation film having a refractive index distribution satisfying the relationship of nx = ny> nz can be obtained. The polymer film containing the cellulose resin as a main component can be obtained, for example, by the method described in JP-A-2001-188128. In addition, a polymer film mainly composed of a polyamideimide resin, a polyether ether ketone resin, or a polyimide resin can be obtained by the method described in JP-A No. 2003-287750.

  The thermoplastic resin preferably has a weight average molecular weight (Mw) measured by a gel permeation chromatography (GPC) method using a tetrahydrofuran solvent, preferably 25,000 to 200,000, and more preferably 30,000 to 100,000. 000, particularly preferably in the range of 40,000 to 80,000. When the weight average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

  Any appropriate molding method can be used as a method for obtaining the polymer film containing the thermoplastic resin as a main component. For example, an appropriate one can be appropriately selected from compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, solvent casting, and the like. Among these production methods, the solvent casting method is preferable. This is because a retardation film excellent in smoothness and optical uniformity can be obtained. Specifically, the above solvent casting method defoams a concentrated solution (dope) obtained by dissolving a resin composition containing a thermoplastic resin as a main component, an additive, etc. in a solvent, and the surface of an endless stainless belt or rotating drum. In addition, the film is cast uniformly in a sheet form and the solvent is evaporated to form a film.

  The conditions employed when molding the polymer film containing the thermoplastic resin as a main component can be appropriately selected depending on the composition and type of the resin, the molding method, and the like. When the solvent casting method is used, examples of the solvent used include cyclopentanone, cyclohexanone, methyl isobutyl ketone, toluene, ethyl acetate, dichloromethane, tetrahydrofuran and the like. The method for drying the solvent is preferably performed while gradually raising the temperature from a low temperature to a high temperature using an air circulation drying oven or the like. The temperature range for drying the solvent is preferably 50 ° C to 250 ° C, more preferably 80 ° C to 150 ° C. By selecting the above conditions, a retardation film having a small Re [590] and excellent in smoothness and optical uniformity can be obtained. Rth [590] can be appropriately adjusted according to the composition and type of the resin, the drying conditions, the thickness of the film after molding, and the like.

  The polymer film containing the thermoplastic resin as a main component may further contain any appropriate additive. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. Etc. The kind and amount of the additive used can be appropriately set according to the purpose. For example, the amount of the additive used is preferably more than 0 and 10 parts by weight or less, more preferably more than 0 and 5 parts by weight or less, and most preferably 0 with respect to 100 parts by weight of the thermoplastic resin. Exceeding 3 parts by weight or less.

  As the retardation film used for the negative C plate, a commercially available polymer film can be used as it is in addition to the above-described one. Moreover, you may use, after giving secondary processes, such as a extending | stretching process and / or a relaxation process, to a commercially available polymer film. Commercially available polymer films include Fuji Photo Film Co., Ltd. trade name “Fujitack Series (UZ, TD, etc.)”, JSR Co., Ltd. trade name “Arton Series (G, F, etc.)”, Nippon Zeon ( The product name “ZEONEX 480” manufactured by Japan Ltd., the product name “ZEONOR” manufactured by Nippon Zeon Co., Ltd., and the like can be given.

  As the retardation film used for the negative C plate, a liquid crystal composition may be used. When a liquid crystal composition is used, the retardation film used for the negative C plate is preferably a solidified layer or a cured layer of a liquid crystal composition containing a planar aligned liquid crystal compound, or a columnar aligned discotic. It is a solidified layer or a cured layer of a liquid crystalline composition containing a liquid crystal compound. In this specification, “planar alignment” refers to a state in which liquid crystal compounds (liquid crystal molecules) are aligned so that the helical axis of the liquid crystal is perpendicular to both substrate surfaces (for example, FIG. 4A). reference). “Columnar alignment” refers to a state in which discotic liquid crystal compounds are arranged so as to be stacked in a columnar shape (see, for example, FIG. 4B). Further, the “solidified layer” refers to a solidified state in which a liquid crystalline composition in a softened, molten or solution state is cooled. The “cured layer” is a layer in which a part or all of the liquid crystalline composition is cross-linked by heat, catalyst, light and / or radiation to be in a stable state of infusible or hardly soluble. Say. In addition, the said hardened layer includes what became the hardened layer via the solidified layer of a liquid crystalline composition.

  In the present specification, the “liquid crystalline composition” means a liquid crystal phase exhibiting liquid crystallinity. Examples of the liquid crystal phase include a nematic liquid crystal phase, a smectic liquid crystal phase, a cholesteric liquid crystal phase, and a columnar liquid crystal phase. The liquid crystalline composition used in the present invention preferably exhibits a nematic liquid crystal phase. This is because a highly transparent retardation film can be obtained.

  The liquid crystalline composition is not particularly limited as long as it contains a liquid crystal compound and exhibits liquid crystallinity. The content of the liquid crystal compound in the liquid crystal composition is preferably 40 to 100 parts by weight, more preferably 50 to 99 parts by weight with respect to 100 parts by weight of the total solid content of the liquid crystal composition. 0.8 parts by weight, and most preferably 70 parts by weight to 99.5 parts by weight. Preferably, the liquid crystal composition further includes a chiral agent. A film having a desired refractive index distribution can be obtained by introducing a chiral agent in an appropriate amount depending on the purpose. Various additives such as a leveling agent, a polymerization initiator, an alignment aid, a heat stabilizer, a lubricant, a lubricant, a plasticizer, and an antistatic agent are added to the liquid crystalline composition as long as the object of the present invention is not impaired. May be included. Moreover, arbitrary thermoplastic resins may be included in the range which does not impair the objective of this invention.

  In the present specification, the “liquid crystal compound” refers to a molecule having a mesogenic group in a molecular structure and forming a liquid crystal phase by a temperature change such as heating or cooling or by the action of a certain amount of solvent. The “mesogen group” means a structural portion necessary for forming a liquid crystal phase, and usually contains a cyclic unit. Specific examples of the mesogenic group include, for example, a biphenyl group, a phenylbenzoate group, a phenylcyclohexane group, an azoxybenzene group, an azomethine group, an azobenzene group, a phenylpyrimidine group, a diphenylacetylene group, a diphenylbenzoate group, a bicyclohexane group, and a cyclohexyl group. Examples thereof include a benzene group and a terphenyl group. In addition, the terminal of these cyclic units may have substituents, such as a cyano group, an alkyl group, an alkoxy group, a halogen group, for example. Especially, as a mesogenic group which consists of a cyclic unit etc., what has a biphenyl group and a phenylbenzoate group is used preferably.

  The liquid crystal compound may be either a temperature transition type (thermotropic) liquid crystal in which a liquid crystal phase develops due to a temperature change or a concentration transition type (lyotropic) liquid crystal in which a liquid crystal phase develops depending on the concentration of a solute in a solution state. Note that the above-described temperature transition type liquid crystal has a phase transition from a crystalline phase (or glass state) to a liquid crystal phase, a reversible tautomatic (enantotropic) phase transition liquid crystal, or a single change in which a liquid crystal phase appears only in a temperature lowering process ( Monotropic) phase transition liquid crystals. Preferably, the liquid crystal compound used in the present invention is a temperature transition type (thermotropic) liquid crystal. This is because it is excellent in productivity, workability, quality and the like when forming a film.

  The liquid crystal compound may be a polymer substance having a mesogenic group in the main chain and / or side chain (also referred to as a polymer liquid crystal), or a low molecular substance having a mesogen group in a part of the molecular structure (low molecular liquid crystal). May also be referred to). Polymer liquid crystal can fix the orientation state of molecules just by cooling from the liquid crystal state, so it has high productivity when forming the film, and the heat resistance, mechanical strength, chemical resistance of the formed film It has the characteristic that it is excellent in property. Since the low molecular liquid crystal is excellent in orientation, it has a feature that a highly transparent film can be easily obtained.

  A retardation film composed of a solidified layer or a cured layer of a liquid crystalline composition containing a liquid crystal compound that is planarly aligned can be obtained, for example, by the method described in JP-A-2003-287623. A retardation film comprising a solidified layer or a cured layer of a liquid crystalline composition containing the columnar-aligned discotic liquid crystal compound can be obtained, for example, by the method described in JP-A-9-117983.

  As a retardation film used for the negative C plate, a retardation film comprising a solidified layer or a cured layer of a liquid crystalline composition containing a planar aligned liquid crystal compound, or a liquid crystal containing a columnar aligned discotic liquid crystal compound. When a retardation film composed of a solidified layer or a cured layer of the adhesive composition is employed, the thickness of the retardation film is preferably 1 μm to 20 μm, and more preferably 1 μm to 10 μm. Within the above range, a retardation film that is thin and excellent in optical uniformity and satisfies the optical characteristics described in the above section C-1 can be obtained.

<< D. Positive A plate
In this specification, “positive A plate” refers to a positive uniaxial optical element whose refractive index distribution satisfies nx> ny = nz. In this specification, ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same. Here, “when ny and nz are substantially the same” means, for example, an in-plane retardation value (Re [590]) and a thickness direction retardation value (Rth [590]). The absolute difference is included: | Rth [590] −Re [590] | is 10 nm or less.

  Referring to FIG. 1 and FIG. 2 described above, the positive A plate 40 is formed such that the slow axis of the positive A plate 40 is substantially perpendicular to the absorption axis of the polarizer 20 and the positive C plate 40 is positive C. It arrange | positions between the plates 50. FIG. As long as this relationship is satisfied, as shown in FIGS. 1A and 1C and FIGS. 2A and 2C, a negative C plate is provided between the polarizer 20 and the positive C plate 50. 30 can be arranged. Preferably, as shown in FIG. 2A, the positive A plate 40 is disposed between the negative C plate 30 and the positive C plate 50. According to such an embodiment, the negative C plate 30 also serves as a protective layer on the liquid crystal cell side of the polarizer 20, and the polarizing element of the present invention is used in a liquid crystal display device in a high temperature and high humidity environment. However, the uniformity of the display screen can be maintained for a long time.

<< D-1. Optical properties of positive A plate >>
Re _PA [590] of the positive A plate used in the present invention is preferably 20 nm or more, more preferably 60 nm to 180 nm, still more preferably 70 nm to 170 nm, and particularly preferably 80 nm to 160 nm. Most preferably, it is 90 nm-150 nm. More specifically, when the polarizing element of the present invention is used in the embodiment of FIG. 2A, the Re _PA [590] of the positive A plate is preferably 70 nm to 130 nm, particularly preferably 80 nm to 130 nm. 120 nm, most preferably 80 nm to 110 nm. When the polarizing element of the present invention is used in the embodiment of FIG. 2 (b) or (c), the Re _PA [590] of the positive A plate is preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm. And most preferably from 130 nm to 150 nm. By setting Re _PA [590] in the above range, the functions of each optical element can be exhibited synergistically, the contrast ratio in the oblique direction of the liquid crystal display device can be increased, and the color shift amount in the oblique direction can be reduced. Can do.

The absolute value of the difference between Re _PA [590] and Rth _PA [590] of the positive A plate used in the present invention: | Rth _PA [590] −Re _PA [590] | is preferably 10 nm or less, more preferably Is 5 nm or less, most preferably 2 nm or less. The theoretical lower limit of | Rth _PA [590] -Re _PA [590] | of the positive A plate is 0 nm.

  Generally, the retardation value of the retardation film may vary depending on the wavelength. This is called the wavelength dispersion characteristic of the retardation film. In this specification, the wavelength dispersion characteristic can be obtained by a ratio of in-plane retardation values measured with light of wavelengths 480 nm and 590 nm at 23 ° C .: Re [480] / Re [590].

Re _PA [480] / Re _PA [590] of the positive A plate is preferably more than 0.8 and less than 1.2, more preferably more than 0.8 and less than 1.0, and particularly preferably More than 0.8 and less than 0.9. When Re _PA [480] / Re _PA [590] is less than 1, the shorter the wavelength, the smaller the characteristic, which is also referred to as “reverse wavelength dispersion characteristic”. A retardation film exhibiting reverse wavelength dispersion characteristics has a constant retardation value in a wide range of visible light. Therefore, when used in a liquid crystal display device, light leakage of a specific wavelength hardly occurs, and the liquid crystal display device displays black. The color shift in the oblique direction at can be further improved.

<< D-2. Positioning means for positive A plate >>
Referring to FIG. 2, any appropriate method may be adopted as a method of arranging the positive A plate 40 between the polarizer 20 and the positive C plate 50 according to the purpose. Preferably, the positive A plate 40 is provided with an adhesive layer (not shown) on both sides thereof, and is bonded to the polarizer 20 and the positive C plate 50 or the negative C plate 30. In this way, by filling the gaps between the optical elements with the adhesive layer, the optical axes of the optical elements can be prevented from shifting when they are incorporated into a liquid crystal display device, or the optical elements can be rubbed and damaged. Can be prevented. Further, it is possible to reduce the adverse effects of reflection and refraction generated at the interface between the layers of each optical element, and to increase the contrast ratio in the front and oblique directions of the liquid crystal display device.

  The thickness of the adhesive layer and the material for forming the adhesive layer are appropriately selected from those exemplified in the above section B-2, the same ranges as those described in the above section C-2, and similar materials. Can be selected.

  As described above, the positive A plate 40 is disposed so that its slow axis is substantially perpendicular to the absorption axis of the polarizer 20. As the degree of deviation from these positional relationships increases, the contrast ratio in the front and oblique directions tends to decrease when used in a liquid crystal display device.

<< D-3. Composition of positive A plate >>
The configuration (laminated structure) of the positive A plate is not particularly limited as long as it satisfies the optical characteristics described in the above section D-1. The positive A plate may be a retardation film alone or a laminate of two or more retardation films. Preferably, the positive A plate is a single retardation film. This is because the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight can be reduced, and the liquid crystal panel can be thinned. When the positive A plate is a laminate, an adhesive layer for adhering two or more retardation films may be included. When the laminate includes two or more retardation films, these retardation films may be the same or different. The details of the retardation film will be described later in section D-4.

Re [590] of the retardation film used for the positive A plate can be appropriately selected depending on the number of the retardation films used. For example, when the positive A plate is composed of the retardation film alone, Re [590] of the retardation film is preferably equal to Re _PA [590] of the positive A plate. Therefore, it is preferable that the retardation value of the adhesive layer used when the positive A plate is laminated on the polarizer or the positive C plate is as small as possible. For example, when the positive A plate is a laminate including two or more retardation films, the sum of Re [590] of each retardation film is equal to Re _PA [590] of the positive A plate. It is preferable to design as follows. Specifically, a positive A plate with Re _PA [590] of 100 nm can be obtained by laminating retardation films with Re [590] of 50 nm so that their slow axes are parallel to each other. it can. In addition, for the sake of simplicity, only the case where the number of retardation films is two or less is illustrated, but it goes without saying that the present invention can also be applied to a laminate including three or more retardation films.

  The total thickness of the positive A plate is preferably 1 μm to 200 μm, more preferably 2 μm to 150 μm, and most preferably 3 μm to 100 μm. By setting it as said range, the optical element excellent in optical uniformity can be obtained.

<< D-4. Retardation film used for positive A plate >>
The retardation film used for the positive A plate is not particularly limited, but a film that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, etc., and that does not cause optical unevenness due to strain is preferably used. .

The absolute value (C [590] (m ² / N)) of the photoelastic coefficient of the retardation film is preferably 1 × 10 ⁻¹² to 200 × 10 ⁻¹² , more preferably 1 × 10 ⁻¹² to 50 × 10 ⁻¹² , most preferably 1 × 10 ^{−12 to} 20 × 10 ⁻¹² . The smaller the absolute value of the photoelastic coefficient, the smaller the deviation and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight when it is used in a liquid crystal display device. A device can be obtained.

  The transmittance of the retardation film measured with light having a wavelength of 590 nm at 23 ° C. is preferably 80% or more, more preferably 85% or more, and most preferably 90% or more. The positive A plate preferably has the same transmittance. The theoretical upper limit of the transmittance is 100%.

  The retardation film is preferably a stretched polymer film mainly composed of a thermoplastic resin. More preferred is a stretched polymer film mainly composed of an amorphous polymer of a thermoplastic resin. Amorphous polymers have the advantage of excellent transparency. In this specification, the “stretched film” refers to a plastic film in which tension is applied to an unstretched film at an appropriate temperature, or tension is further applied to a previously stretched film to increase molecular orientation in a specific direction. .

  The thickness of the stretched polymer film containing the thermoplastic resin as a main component can be appropriately selected according to the retardation value to be designed, the number of laminated layers, and the like. Preferably they are 5 micrometers-120 micrometers, More preferably, they are 10 micrometers-100 micrometers. Within the above range, a retardation film excellent in mechanical strength and optical uniformity and satisfying the optical characteristics described in the above section D-1 can be obtained.

  As the thermoplastic resin, for example, an appropriate material is selected from the materials described in the above section C-4. Preferably, the retardation film used for the positive A plate is a stretched film of a polymer film containing a styrene resin. The styrenic resin is used for the purpose of adjusting the wavelength dispersion characteristic and the photoelastic coefficient of the retardation film. In the present specification, the “styrene resin” refers to a polymer obtained by polymerizing a styrene monomer. Examples of the styrenic resin include polystyrene, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, acrylonitrile / ethylene / styrene copolymer, styrene / maleimide copolymer, styrene / maleic anhydride copolymer, Examples include styrene / methyl methacrylate copolymers.

  The styrene resin preferably has a weight average molecular weight (Mw) measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably 1,000 to 400,000, more preferably 2,000 to 300,000. Of the range. When the weight average molecular weight is in the above range, the solubility, moldability, and operability of extrusion can be improved.

  The content of the styrenic resin is preferably 10 to 50 parts by weight, more preferably 20 to 40 parts by weight with respect to 100 parts by weight of the solid content of the retardation film. By setting it as said range, a phase difference film has a small photoelastic coefficient, shows a favorable wavelength dispersion characteristic, and is excellent in durability, mechanical strength, and transparency.

  Particularly preferably, the retardation film used for the positive A plate is a stretched film of a polymer film mainly composed of a resin composition containing a styrene resin and another thermoplastic resin. As said other thermoplastic resin, a suitable thing is selected from the material as described in said C-4 term. Preferably, the other thermoplastic resin is a cycloolefin resin, and particularly preferably a cycloolefin resin obtained by hydrogenating a ring-opening polymer of a norbornene monomer. A stretched polymer film mainly composed of a resin composition containing a styrene resin and a cycloolefin resin has a small photoelastic coefficient, exhibits extremely good wavelength dispersion characteristics, and has durability and mechanical strength. Excellent transparency.

  The cycloolefin resin obtained by hydrogenating the ring-opening polymer of the norbornene monomer can be obtained by subjecting the norbornene monomer to a metathesis reaction to obtain a ring-opening polymer, and further hydrogenating the ring-opening polymer. it can. For example, NTS Co., Ltd. “Optical polymer material development and application technology” p. 103-p. 111 (2003 edition).

Examples of the norbornene-based monomer include norbornene; norbornene alkyl derivatives such as 5-methyl-2-norbornene, 5-ethyl-2-norbornene, and 5-dimethyl-2-norbornene;
Norbornene alkylidene derivatives such as 5-ethylidene-2-norbornene; dicyclopentadiene; dicyclopentadiene derivatives such as 2,3-dihydrodicyclopentadiene; 1,4: 5,8-dimethano-1,4,4a, 5 Examples include octahydronaphthalene derivatives such as 6,7,8a-octahydronaphthalene and 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8a-octahydronaphthalene. It is done.

  The hydrogenation rate of the cycloolefin resin obtained by hydrogenating the ring-opening polymer of the norbornene monomer is usually 90% or more from the viewpoint of heat deterioration resistance and light deterioration resistance. Preferably it is 95% or more. More preferably, it is 99% or more.

  The cycloolefin resin obtained by hydrogenating the ring-opening polymer of the norbornene monomer preferably has a weight average molecular weight (Mw) measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably 20,000 to 300. , More preferably in the range of 30,000 to 200,000. When the weight average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and extrusion operability can be obtained.

  As a method for obtaining a polymer film containing a thermoplastic resin as a main component used for the positive A plate, a method similar to the molding method described in the above section C-4 can be employed. Among these production methods, the extrusion molding method is preferable. This is because a retardation film excellent in smoothness and optical uniformity can be obtained. Specifically, the extrusion molding method involves heating and melting a resin composition containing a thermoplastic resin as a main component, an additive, etc., and using a T-die or the like to form a sheet on the surface of a casting roll. It is a method of forming a film by extruding and cooling. When two or more kinds of resins are blended and used, there are no particular restrictions on the resin mixing method. For example, when an extrusion molding method is used, the resin is uniformly mixed and melted at a predetermined ratio. Can be mixed.

  The conditions adopted at the time of molding of the polymer film containing the thermoplastic resin as a main component can be appropriately selected according to the composition and type of the resin, the molding method, and the like. When the extrusion molding method is used, for example, a resin heated and melted at 240 ° C. to 300 ° C. is discharged into a sheet shape and gradually cooled from a high temperature to a low temperature using a take-up roll (cooling drum) or the like. Is preferably used. By selecting the above conditions, a retardation film having desired Re [590] and Rth [590] and excellent in smoothness and optical uniformity can be obtained.

  The polymer film containing the thermoplastic resin as a main component may further contain any appropriate additive. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. Etc. The kind and amount of the additive used can be appropriately set according to the purpose. For example, the amount of the additive used is preferably more than 0 and 10 parts by weight or less, more preferably more than 0 and 5 parts by weight or less, and most preferably 0 with respect to 100 parts by weight of the thermoplastic resin. Exceeding 3 parts by weight or less.

  Any appropriate stretching method may be employed as a method of stretching a polymer film containing a thermoplastic resin as a main component. Specific examples include a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, and a longitudinal and transverse sequential biaxial stretching method. As the stretching means, any suitable stretching machine such as a roll stretching machine, a tenter stretching machine, and a biaxial stretching machine can be used. When performing the above-mentioned heat stretching, the temperature may be continuously changed or may be changed stepwise. Further, the stretching process may be divided into two or more times, and stretching and shrinkage (relaxation) may be combined. The stretching direction may be the film longitudinal direction (MD direction) or the width direction (TD direction). Moreover, you may extend | stretch in the diagonal direction (diagonal extending | stretching) using the extending | stretching method of FIG. 1 of Unexamined-Japanese-Patent No. 2003-262721. Re [590] and Rth [590] of the retardation film used for the positive A plate are appropriately adjusted depending on the retardation value and thickness before stretching, the stretching ratio, the stretching temperature, and the like.

  Preferably, the polymer film before being stretched has the same in-plane and thickness direction retardation values as much as possible. Specifically, the absolute value of the difference between Re [590] and Rth [590] of the polymer film before being stretched: | Rth [590] −Re [590] | is 5 nm or less. Preferably used. More preferably, the in-plane and thickness direction retardation values of the polymer film before being stretched are equally small. Specifically, Re [590] and Rth [590] of the polymer film before being stretched are each 10 nm or less, more preferably 5 nm or less, and most preferably 2 nm or less. The Re [590] and Rth [590] of the polymer film before being stretched are preferably adjusted at the time of film formation from the viewpoint of economy and workability. When Re [590] and Rth [590] of the film are different from each other, it can be adjusted by subjecting the polymer film to secondary processing such as stretching, shrinkage (relaxation), and heat (relaxation). .

  The retardation value is that the temperature in the stretching oven (also referred to as stretching temperature) when stretching the polymer film containing the thermoplastic resin as a main component is equal to or higher than the glass transition temperature (Tg) of the polymer film. Is more preferable in terms of being easy to be uniform in the width direction and being difficult to crystallize (white turbidity). The stretching temperature is preferably Tg + 1 ° C. to Tg + 30 ° C. Typically, the temperature is 110 ° C to 200 ° C, more preferably 120 ° C to 170 ° C. The glass transition temperature can be determined by a DSC method according to JIS K 7121: 1987.

  The specific method for keeping the temperature in the drawing oven constant is not particularly limited, but it is an air circulation type thermostatic oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, for temperature adjustment. An appropriate one is selected from heating methods such as a heated roll, a heat pipe roll, or a metal belt, and a temperature control method.

  The stretching ratio when stretching the polymer film is selected appropriately depending on the composition of the polymer film, the type of volatile component, the residual amount of volatile component, the retardation value to be designed, etc. Is done. Specifically, the draw ratio is usually more than 1 time and 3 times or less, preferably 1.1 times to 2 times, more preferably 1.2 times to 1.8 times the original length. Is double. Moreover, the feed rate at the time of stretching is not particularly limited, but is preferably 1 m / min to 20 m / min from the viewpoint of mechanical accuracy and stability of the stretching apparatus.

  Moreover, as a retardation film used for positive A plate, the thing using a liquid crystalline composition may be used. When a liquid crystalline composition is used, the retardation film used for the positive A plate is preferably a solidified layer or a cured layer of a liquid crystalline composition containing a homogeneously aligned liquid crystal compound. In the present specification, “homogeneous alignment” refers to a state in which liquid crystal compounds are arranged in parallel and in the same direction with respect to a film plane. Examples of the liquid crystal composition and the liquid crystal compound used for the positive A plate include the same as those described in the above section C-4.

  A retardation film composed of a solidified layer or a cured layer of a liquid crystalline composition containing a homogeneously aligned liquid crystal compound can be obtained, for example, by the method described in JP-A No. 2002-156526.

  As the retardation film used for the positive A plate, the thickness of the retardation film when a retardation film comprising a solidified layer or a cured layer of a liquid crystalline composition containing a homogeneously oriented liquid crystal compound is employed is preferably Is 1 μm to 20 μm, more preferably 1 μm to 10 μm. Within the above range, a retardation film that is thin and excellent in optical uniformity and satisfies the optical characteristics described in the above section D-1 can be obtained.

<< E. Positive C plate
In this specification, the “positive C plate” refers to a positive uniaxial optical element whose refractive index distribution satisfies nz> nx = ny. Ideally, a positive uniaxial optical element whose refractive index distribution satisfies nz> nx = ny has an optical axis in the normal direction. In the present specification, nx = ny includes not only the case where nx and ny are completely the same, but also the case where nx and ny are substantially the same. Here, “when nx and ny are substantially the same” includes a case where the in-plane retardation value (Re [590]) is 10 nm or less.

  Referring to FIGS. 1 and 2, the positive C plate 50 is disposed at least between the positive A plate 40 and the liquid crystal cell 100. Preferably, as shown in FIG. 2A, the positive C plate 50 is disposed between the positive A plate 40 and the liquid crystal cell 100 without the negative C plate 30 interposed therebetween. According to such an embodiment, the negative C plate 30 also serves as a protective layer on the liquid crystal cell side of the polarizer 20, and the polarizing element of the present invention is used in a liquid crystal display device in a high temperature and high humidity environment. However, the uniformity of the display screen can be maintained for a long time.

<< E-1. Optical properties of positive C plate >>
The Re _PC [590] of the positive C plate used in the present invention is preferably 5 nm or less, more preferably 2 nm or less. The theoretical lower limit of Re _PC [590] of the positive C plate is 0 nm.

Rth _PC [590] of the positive C plate is −60 nm or less, preferably −350 nm to −60 nm. More preferably, it is -310 nm--60 nm. More specifically, referring to FIG. 2, when the polarizing element of the present invention is used in the embodiment of FIG. 2A, the Rth _PC [590] is preferably −230 nm to −60 nm, More preferably, it is -190 nm--60 nm, Most preferably, it is -160 nm--60 nm. When the polarizing element of the present invention is used in the embodiment of FIG. 2B or 2C, the Rth _PC [590] is preferably −350 nm to −80 nm, more preferably −310 nm to −80 nm. Most preferably, it is -270 nm to -80 nm. By setting it as the above range, the function of each optical element is exhibited synergistically, the contrast ratio in the oblique direction of the liquid crystal display device can be increased, and the color shift amount in the oblique direction can be reduced.

In addition, the positive C plate of _Rth PC [590] is the sum of the _{Rth PC} [590] of the positive C plate and _{Rth NC} [590] of the negative C plate _{(Rth the add)} found above section C-1 It is preferable to adjust within the range described in.

<< E-2. Positioning means for positive C plate >>
Referring to FIG. 2, any appropriate method may be adopted as a direction in which the positive C plate 50 is disposed between the positive A plate 40 and the liquid crystal cell 100 according to the purpose. Preferably, the positive C plate 50 is provided with an adhesive layer (not shown) on both sides thereof, and is adhered to the liquid crystal cell 100, the positive A plate 40 or the negative C plate 30. In this way, by filling the gaps between the optical elements with the adhesive layer, the optical axes of the optical elements can be prevented from shifting when they are incorporated into a liquid crystal display device, or the optical elements can be rubbed and damaged. Can be prevented. Further, it is possible to reduce the adverse effects of reflection and refraction generated at the interface between the layers of each optical element, and to increase the contrast ratio in the front and oblique directions of the liquid crystal display device.

  The thickness of the adhesive layer and the material for forming the adhesive layer are appropriately selected from those described in the above section B-2, the same ranges as those described in the above section C-2, and similar materials. Can be selected.

  In the positive C plate 50, when nx and ny are completely the same, no retardation value is generated in the plane, so that the slow axis is not detected, and the absorption axis of the polarizer 20 and the delay of the positive A plate are not detected. It can be arranged independently of the phase axis. Even if nx and ny are substantially the same, a slow axis may be detected if nx and ny are slightly different. In this case, the positive C plate 50 is preferably arranged so that its slow axis is substantially parallel to or substantially perpendicular to the absorption axis of the polarizer 20. As the degree of deviation from these positional relationships increases, the contrast ratio in the front and oblique directions tends to decrease when used in a liquid crystal display device.

<< E-3. Composition of positive C plate >>
The configuration (laminated structure) of the positive C plate is not particularly limited as long as it satisfies the optical characteristics described in the above section E-1. The positive C plate may be a retardation film alone or a laminate of two or more retardation films. Preferably, the positive C plate is a single retardation film. This is because the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight can be reduced, and the liquid crystal panel can be thinned. When the positive C plate is a laminate, an adhesive layer for adhering two or more retardation films may be included. When the laminate includes two or more retardation films, these retardation films may be the same or different. Details of the retardation film will be described later in Section E-4.

Rth [590] of the retardation film used for the positive C plate can be appropriately selected depending on the number of retardation films used. For example, when the positive C plate is composed of the retardation film alone, it is preferable that Rth [590] of the retardation film is equal to Rth _PC [590] of the positive C plate. Therefore, the retardation value of the adhesive layer used when the positive C plate is laminated on the positive A plate or the liquid crystal cell is preferably as small as possible. For example, when the positive C plate is a laminate including two or more retardation films, the sum of Rth [590] of each retardation film is equal to Rth _PC [590] of the positive C plate. It is preferable to design as follows. More specifically, for example, a positive C plate having Rth _PC [590] of −100 nm can be obtained by laminating two retardation films having Rth [590] of −50 nm. Alternatively, a retardation film having Rth [590] of −20 nm and a retardation film having Rth [590] of −80 nm may be laminated. At this time, it is preferable to laminate | stack so that the slow axis of two retardation films may each orthogonally cross. This is because the in-plane retardation value can be reduced. In addition, for the sake of simplicity, only the case where the number of retardation films is two or less is illustrated, but it goes without saying that the present invention can be applied to a laminate including three or more retardation films.

  The total thickness of the positive C plate is preferably 0.5 μm to 200 μm, more preferably 1 μm to 150 μm, and most preferably 3 μm to 100 μm. By setting it as said range, the optical element excellent in optical uniformity can be obtained.

<< E-4. Retardation Film Used for Positive C Plate >>
As the retardation film used for the positive C plate, a film excellent in transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferably used. Preferably, the retardation film used for the positive C plate is a solidified layer or a cured layer of a liquid crystalline composition containing a liquid crystal compound having homeotropic alignment. In this specification, “homeotropic alignment” refers to a state in which a liquid crystal compound contained in a liquid crystal composition is aligned in parallel and uniformly with respect to the film normal direction. Examples of the liquid crystal composition and the liquid crystal compound used for the positive C plate are the same as those described in the above section C-4.

  More preferably, the retardation film used for the positive C plate is a solidified layer or a cured layer of a liquid crystalline composition containing a homeotropically aligned liquid crystal compound, and the liquid crystalline composition is a part of a molecular structure. In addition, a low molecular liquid crystal having at least one polymerizable or crosslinkable functional group is included. Particularly preferably, the liquid crystalline composition contains a low molecular liquid crystal having at least two polymerizable or crosslinkable functional groups in a part of the molecular structure. If such a liquid crystal compound is used, the mechanical strength of the retardation film is increased by polymerizing (or cross-linking) the polymerizable (or cross-linking) functional group by polymerization (or cross-linking) reaction. A retardation film having excellent stability can be obtained. For example, as a low-molecular liquid crystal having one mesogen group and two polymerizable functional groups in a part of the molecular structure, a product name “Paliocolor LC242” (Δn = 0.131) manufactured by BASF, or a product name “CB483” manufactured by HUNSUMANAN (Δn = 0.080) and the like.

  Any appropriate functional group can be selected as the polymerizable functional group. For example, acryloyl group, methacryloyl group, epoxy group, vinyl ether group and the like can be mentioned. Among these, an acryloyl group and a methacryloyl group are preferably used in that a retardation film having high reactivity and excellent transparency can be obtained.

  The thickness of the retardation film composed of a solidified layer or a cured layer of a liquid crystalline composition containing a homeotropically aligned liquid crystal compound varies depending on the retardation value to be designed, but is preferably 0.6 μm to 20 μm. More preferably, it is 0.8 micrometer-10 micrometers, Most preferably, it is 0.8 micrometer-2.5 micrometers. By setting it as the above range, it is possible to obtain a retardation film having excellent productivity and workability in forming a film, having practically sufficient mechanical strength, and excellent optical uniformity.

  The refractive index (ne) of extraordinary light and the refractive index of ordinary light (no) measured at a wavelength of 589 nm at 23 ° C. of a retardation film comprising a solidified layer or a cured layer of a liquid crystalline composition containing a liquid crystal compound that is homeotropically aligned. ) (Also referred to as birefringence index (Δn)): Δn = ne−no is preferably −0.20 to −0.04, more preferably −0.18 to −0.05. Most preferably, it is -0.14 to -0.07. By using a retardation film having a birefringence in the above range, the optical properties described in the above section E-1 are satisfied, and the thickness of the retardation film is adjusted to a range excellent in productivity and workability. can do.

  The transmittance of the retardation film composed of a solidified layer or a cured layer of the liquid crystalline composition containing the homeotropically aligned liquid crystal compound, measured with light at a wavelength of 590 nm at 23 ° C., is preferably 80% or more, and more preferably Is 85% or more, and most preferably 90% or more. The positive C plate preferably has the same transmittance. The theoretical upper limit of the transmittance is 100%.

The retardation film composed of a solidified layer or a cured layer of a liquid crystalline composition containing a liquid crystal compound that is homeotropically aligned may further contain a polymer liquid crystal represented by the following general formula (I). The polymer liquid crystal is used for the purpose of improving the orientation of the liquid crystal compound.
In the general formula (I), l is an integer of 14 to 20, and when the sum of m and n is 100, m is 50 to 70 and n is 30 to 50.

  The content of the polymer liquid crystal is preferably 100 parts by weight based on the total solid content of the retardation film composed of a solidified layer or a cured layer of a liquid crystalline composition containing a liquid crystal compound aligned in a homeotropic molecular arrangement. The amount is 10 to 40 parts by weight, and more preferably 15 to 30 parts by weight.

  A retardation film comprising a solidified layer or a cured layer of a liquid crystalline composition containing a homeotropically aligned liquid crystal compound can be obtained, for example, through the following steps 1 to 3. Specifically, (Step 1) a step of subjecting the surface of the base material (also referred to as a support) to vertical alignment treatment; (Step 2) the surface of the base material that has been subjected to the vertical orientation treatment of the liquid crystalline composition A step of applying a solution or dispersion and homeotropically aligning the liquid crystal compound in the liquid crystalline composition; and (step 3) a step of drying and solidifying the liquid crystalline composition. Preferably, the method for forming the retardation film includes, after Step 1 to Step 3, (Step 4), a step of irradiating ultraviolet rays to cure the liquid crystalline composition. Usually, the substrate is peeled off before the retardation film is put into practical use.

  FIG. 5 is a schematic diagram for explaining an outline of a method for producing a retardation film used for a positive C plate as an example of a preferred embodiment. In this step, the base material 402 is supplied from the feeding unit 401, conveyed by the guide roll 403, and the alignment agent solution or dispersion is applied in the first coater unit 404. The base material coated with the alignment agent is sent to the first drying means 405, and the solvent is evaporated to form an alignment agent layer (also referred to as alignment film) on the surface. Next, the base material 406 on which the alignment film is formed is coated with a solution or dispersion liquid of the liquid crystalline composition in the second coater unit 407, and the solvent is evaporated in the second drying means 408. On the surface thereof, a solidified layer of a liquid crystalline composition containing a homeotropically aligned liquid crystal compound is formed. Next, the base material 409 on which the solidified layer of the liquid crystalline composition containing the liquid crystal compound aligned in the homeotropic molecular arrangement is formed is sent to the ultraviolet irradiation unit 410, and the surface of the solidified layer is irradiated with ultraviolet rays. Then, a cured layer of a liquid crystalline composition containing a homeotropically aligned liquid crystal compound is formed. The ultraviolet irradiation unit 410 typically includes an ultraviolet lamp 412 and a temperature control unit 411. Subsequently, the base material 413 on which this hardened layer is formed is wound up by the winding unit 414 and used for the manufacturing process of the polarizing element (sticking process with the polarizer).

  The base material used in the above step 1 (step of subjecting the surface of the base material to vertical alignment treatment) is used for casting a solution or dispersion of the liquid crystalline composition thinly and uniformly. An appropriate material can be selected as the material for forming the substrate. Specific examples include glass substrates such as glass plates and quartz substrates, polymer substrates such as films and plastics substrates, metal substrates such as aluminum and iron, inorganic substrates such as ceramic substrates, and semiconductors such as silicon wafers. Examples include base materials. Preferably, the substrate is a polymer substrate. This is because the surface smoothness of the base material and the wettability of the liquid crystal composition are excellent, and continuous production by a roll is possible, and the productivity can be greatly improved. Usually, the substrate is peeled off before the retardation film is put into practical use.

  Examples of the material for forming the polymer substrate include thermosetting resins, ultraviolet curable resins, thermoplastic resins, thermoplastic elastomers, and biodegradable plastics. Of these, thermoplastic resins are preferably used. The thermoplastic resin may be an amorphous polymer or a crystalline polymer. Since the amorphous polymer is excellent in transparency, it has an advantage that the retardation film of the present invention can be used as it is for a liquid crystal panel or the like without peeling off from the substrate. On the other hand, since the crystalline polymer is excellent in rigidity, strength, and chemical resistance, it has an advantage that it is excellent in production stability when the retardation film of the present invention is produced. The polymer substrate may also serve as a retardation film used for the positive A plate or the negative C plate in the present invention. For example, referring to FIGS. 2 (a) and 2 (b), the surface of the positive A plate 40 using a stretched polymer film mainly composed of a thermoplastic resin as a base material (support) is used. In addition, a solidified layer or a cured layer (as a result, the positive C plate 50) of a liquid crystalline composition containing a liquid crystal compound that is homeotropically aligned may be formed. 2 (b) and 2 (c), a polymer film mainly composed of a thermoplastic resin is used for the negative C plate 30 as a base material (support), and a homeosphere is formed on the surface. A solidified layer or a cured layer (as a result, the positive C plate 50) of a liquid crystalline composition containing a liquid crystal compound aligned in a tropic molecular arrangement may be formed.

  The vertical alignment treatment is used for homeotropic alignment of the liquid crystal compound in the liquid crystalline composition. Any appropriate method can be used as the vertical alignment treatment. Preferably, a method of forming an aligning agent layer (also referred to as an alignment film) by adsorbing an aligning agent on the surface of the substrate can be used. According to this method, a retardation film with extremely few alignment defects (disclinations) of the liquid crystal compound can be produced.

  In the vertical alignment treatment, examples of the method for adsorbing the alignment agent on the surface of the substrate include a solution coating method, a plasma polymerization method, and a sputtering method. A solution coating method is preferable. It is because it is excellent in continuous productivity, workability, and economy, and the liquid crystal compound can be uniformly aligned. In the present specification, the “solution coating method” refers to a method of forming an alignment film by applying a solution or dispersion of an alignment agent on the surface of a substrate and drying it.

  Any appropriate alignment agent can be selected as the alignment agent used in the vertical alignment treatment. Specific examples include lecithin, stearic acid, hexadecyltrimethylammonium bromide, octadecylamine hydrochloride, monobasic chromium complex (eg, myristic acid chromium complex, perfluorononanoic acid chromium complex, etc.), organic silane (example: Silane coupling agent, siloxane, etc.), perfluorodimethylcyclohexane, tetrafluoroethylene, polytetrafluoroethylene and the like. Particularly preferred as the aligning agent is organosilane. This is because it is excellent in workability, product quality, and alignment ability of the liquid crystal compound. Specific examples of the organic silane alignment agent include an alignment agent mainly composed of tetraethoxysilane [Corcoat Co., Ltd., trade name “ethyl silicate”].

  As a method of preparing the alignment agent solution or dispersion, a commercially available alignment agent solution or dispersion may be used, or a solvent may be added to the commercially available alignment agent solution or dispersion. Good. Further, the solid content of the alignment agent may be dissolved in various solvents and used, or the alignment agent, various additives, and a solvent may be mixed and dissolved.

  The total solid content concentration of the aligning agent solution varies depending on the solubility, coating viscosity, wettability on the substrate, thickness after coating, etc., but is usually 0.05 to 100 parts by weight of the solvent. 20 parts by weight, more preferably 0.5 to 10 parts by weight, particularly preferably 1 to 5 parts by weight. If it is said range, a phase difference film with high surface uniformity can be obtained.

  As the solvent used for the aligning agent, a liquid substance in which the aligning agent is uniformly dissolved to form a solution is preferably used. The solvent may be a nonpolar solvent such as benzene or hexane, or a polar solvent such as water or alcohol. The solvent may be an inorganic solvent such as water, alcohols, ketones, ethers, esters, aliphatic and aromatic hydrocarbons, halogenated hydrocarbons, amides, cellosolves. Organic solvents such as Preferably, it is at least one solvent selected from cyclopentanone, cyclohexanone, methyl ethyl ketone, and tetrahydrofuran. These solvents are preferable because they do not cause erosion that has a practically adverse effect on the substrate and can sufficiently dissolve the alignment agent.

  As a method of applying the solution or dispersion of the aligning agent, any appropriate coating method using a coater can be selected and used. Specific examples of the above coater include reverse roll coater, forward rotation roll coater, gravure coater, knife coater, rod coater, slot orifice coater, curtain coater, fountain coater, air doctor coater, kiss coater, dip coater, bead coater, blade coater, cast Examples include a coater, a spray coater, a spin coater, an extrusion coater, and a hot melt coater. Among these, as a coater, a reverse roll coater, a normal rotation roll coater, a gravure coater, a rod coater, a slot orifice coater, a curtain coater, a fountain coater, and a spin coater are preferable. With the coating method using the above coater, the alignment film can be formed very thin and uniformly.

  Examples of methods for drying the alignment agent solution or dispersion (also referred to as drying means) include, for example, an air circulation type thermostatic oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, and temperature control. An appropriate one can be selected from heating methods such as a heated roll, a heat pipe roll, or a metal belt, and a temperature control method.

  The temperature for drying the alignment agent solution or dispersion is preferably not more than the glass transition temperature (Tg) of the substrate. Specifically, it is preferably 50 ° C to 180 ° C, more preferably 80 ° C to 150 ° C. The drying time is, for example, 1 minute to 20 minutes, preferably 1 minute to 10 minutes, and more preferably 1 minute to 5 minutes.

  In the above step 2 (step of applying a solution or dispersion of a liquid crystalline composition to the surface of a substrate subjected to vertical alignment treatment and homeotropically aligning the liquid crystal compound in the liquid crystalline composition) As a method for applying the liquid crystal composition solution or dispersion, an appropriate one can be selected from the same methods as the alignment agent coating method described above.

  As a method for preparing the liquid crystal composition solution or dispersion liquid, a commercially available liquid crystal composition solution or dispersion liquid may be used, and a solvent is further added to the commercially available liquid crystal composition solution or dispersion liquid. You may add and use. Further, the solid content of the liquid crystalline composition may be used by dissolving it in various solvents, or an aligning agent, various additives, and a solvent may be mixed and dissolved.

  The total solid content concentration of the liquid crystalline composition solution varies depending on solubility, coating viscosity, wettability on the substrate, thickness after coating, etc., but preferably 10 to 100 parts by weight of the solvent. 100 parts by weight, more preferably 20 to 80 parts by weight, particularly preferably 30 to 60 parts by weight. If it is said range, a phase difference film with high surface uniformity can be obtained.

  As the solvent used for the liquid crystal composition, a liquid substance that uniformly dissolves the liquid crystal composition to form a solution and that hardly dissolves the alignment film is preferably used. The solvent is preferably at least one solvent selected from cyclopentanone, cyclohexanone, methyl isobutyl ketone, toluene, and ethyl acetate. These solvents are preferable because they do not cause erosion that has a practically adverse effect on the substrate and can sufficiently dissolve the liquid crystalline composition.

  In the step 3 (step of drying and solidifying the liquid crystalline composition), as a method of drying the liquid crystalline composition (also referred to as a drying means), for example, an air circulation type constant temperature oven in which hot air or cold air circulates, An appropriate one can be selected from heating methods and temperature control methods such as a heater using microwaves or far infrared rays, a roll heated for temperature adjustment, a heat pipe roll or a metal belt.

  The temperature at which the liquid crystalline composition is dried is preferably in the temperature range showing the liquid crystal phase of the liquid crystalline composition and not more than the glass transition temperature (Tg) of the substrate. Specifically, it is preferably 50 ° C to 130 ° C, more preferably 70 ° C to 120 ° C. The drying time is, for example, 1 minute to 20 minutes, preferably 1 minute to 10 minutes, and more preferably 1 minute to 5 minutes. If it is said conditions, a highly uniform retardation film can be produced.

  Preferably, the retardation film used for the positive C plate includes (step 4) a step of irradiating with ultraviolet rays to cure the liquid crystalline composition after the steps 1 to 3. In this case, the liquid crystal composition preferably includes a low molecular liquid crystal (liquid crystal compound) having at least one polymerizable or crosslinkable functional group in a part of the molecular structure. By cross-linking the liquid crystal compound, the mechanical strength of the retardation film is increased, and a retardation film having excellent durability and dimensional stability can be obtained.

  Examples of the method for curing the liquid crystalline composition include an ultrahigh pressure mercury lamp, a dielectric excimer discharge lamp, a flash UV lamp, a high pressure mercury lamp, a low pressure mercury lamp, a deep UV lamp, a xenon lamp, a xenon flash lamp, and a metal halide lamp. An appropriate method can be selected from a method using an irradiation device using a light source as described above.

  The wavelength of the light source used for the irradiation of the ultraviolet light can be determined according to the wavelength region in which the polymerizable or crosslinkable functional group of the liquid crystal compound used in the present invention has optical absorption, and is usually 210 nm to 380 nm. Used. More preferably, it is 250 nm-380 nm. Further, the wavelength of the light source is preferably used by cutting a vacuum ultraviolet ray region of 100 nm to 200 nm with a filter or the like in order to suppress the photodecomposition reaction of the liquid crystal compound. If it is said range, a liquid crystal compound will fully harden | cure by superposition | polymerization or a crosslinking reaction, and the retardation film excellent in mechanical strength can be obtained.

Preferably the irradiation light amount of the ultraviolet light, the value measured at a wavelength of 365nm ^{is, 30mJ / cm 2 ~1000mJ / cm} 2
, And still more ^preferably from ^{50mJ / cm 2 ~800mJ / cm 2} , particularly preferably from ^{100mJ / cm 2 ~500mJ / cm 2} . When the irradiation light quantity is in the above range, the liquid crystalline composition is sufficiently crosslinked by a polymerization reaction, and a retardation film having excellent mechanical strength can be obtained.

  The temperature in the irradiation apparatus (also referred to as irradiation temperature) during irradiation with the ultraviolet light is preferably kept below the liquid crystal phase-isotropic phase transition temperature (Ti) of the liquid crystalline composition. More preferably, it is the range of Ti-5 degrees C or less, Most preferably, it is the range of Ti-10 degrees C or less. Specifically, the irradiation temperature is preferably 15 ° C to 90 ° C, more preferably 15 ° C to 60 ° C. If it is said temperature range, a highly uniform retardation film can be produced.

  Examples of the method for maintaining the irradiation temperature constant (also referred to as temperature control means) include, for example, an air circulation type constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, and heating for temperature adjustment. An appropriate one can be selected from a heating method such as a roll, a heat pipe roll or a metal belt or a temperature control method.

<< F. Overview of the entire LCD panel >>
The polarizing element of the present invention is disposed on at least one side of a liquid crystal cell and used as a liquid crystal panel. Preferably, the polarizing element is disposed on the viewing side of the liquid crystal cell in order to greatly increase the contrast in the oblique direction of the liquid crystal display device. The type of the liquid crystal cell is not particularly limited, and any of a transmissive type, a reflective type, and a reflective transflective type can be used.

  FIG. 6 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. FIG. 7 is a schematic perspective view of the liquid crystal panel. It should be noted that for the sake of easy understanding, the ratio of the vertical, horizontal, and thickness of each component in FIGS. 6 and 7 is different from the actual ratio. The liquid crystal panel 150 includes a liquid crystal cell 100, the polarizing element 10 of the present invention disposed on the viewing side of the liquid crystal cell 100, a second polarizer 60 disposed on the backlight side of the liquid crystal cell 100, Another retardation film 70 is provided between the liquid crystal cell 100 and the second polarizer 60. As shown in FIG. 1, the polarizing element 10 has a first polarizer 20 on the outermost side. The first polarizer 20 and the second polarizer 60 are arranged so that their absorption axes are orthogonal to each other. In practice, any appropriate protective layer (not shown) may be disposed outside the first polarizer 20 and the second polarizer 60. The liquid crystal panel of the present invention is not limited to the illustrated example, and any constituent member such as any film or adhesive layer (preferably having isotropic optical characteristics) is provided between the constituent members. Can be arranged. Although FIG. 6 shows only the case where the polarizing element 10 is employed, the polarizing elements 11 and 12 can also be applied to the liquid crystal cell similarly to the illustrated example. It goes without saying that a polarizing element according to still another embodiment of the present invention (a polarizing element not illustrated in FIG. 1) is applicable.

<< G. Liquid Crystal Cell >>
Referring to FIG. 6, the liquid crystal cell 100 includes a pair of glass substrates (101 and 102) and a liquid crystal layer 103 as a display medium disposed between the substrates (none of which is shown). One glass substrate (active matrix substrate) includes an active element (typically a TFT) for controlling the electro-optic effect of the liquid crystal, a scanning line for supplying a gate signal to the active element, and a signal line for supplying a source signal. Provided (none shown). The other glass substrate (color filter substrate) is provided with a colored layer as a color filter, a light shielding layer (also referred to as a black matrix), and an ITO layer (all not shown). The distance (cell gap) between the two glass substrates is controlled by a spacer (not shown). For example, an alignment film (not shown) made of polyimide is provided on the side of the glass substrate in contact with the liquid crystal layer.

  Examples of the driving mode of the liquid crystal cell include a twisted nematic (TN) mode, a super twisted nematic (STN) mode, a horizontal alignment (ECB) mode, a vertical alignment (VA) mode, and an in-plane switching (IPS) mode. , Bend nematic (OCB) mode, hybrid alignment (HAN) mode, ferroelectric liquid crystal (SSFLC) mode, antiferroelectric liquid crystal (AFLC) mode, and the like. Preferably, the polarizing element of the present invention is used for an IPS mode, VA mode, or OCB mode liquid crystal cell. Most preferred is an IPS mode liquid crystal cell.

  The above-mentioned twisted nematic (TN) mode liquid crystal cell is a nematic liquid crystal having positive dielectric anisotropy sandwiched between two substrates, and the liquid crystal molecules are aligned by the surface alignment treatment of the glass substrate. The one twisted 90 degrees. Specific examples include the liquid crystal cell described in “Liquid Crystal Dictionary” on page 158 (1989) and the liquid crystal cell described in JP-A-63-279229.

  The vertical alignment (VA) mode liquid crystal cell uses a voltage-controlled birefringence (ECB) effect, and nematic liquid crystal having a negative dielectric anisotropy between transparent electrodes when no voltage is applied. Means a vertically aligned liquid crystal cell. Specific examples include liquid crystal cells described in JP-A-62-210423 and JP-A-4-153621. In addition, as described in JP-A No. 11-258605, the VA mode liquid crystal cell includes a substrate provided with a slit in a pixel or a substrate on which a protrusion is formed in order to enlarge a viewing angle. By using it, it may be a multi-domain MVA mode liquid crystal cell. Furthermore, as described in JP-A-10-123576, a VATN mode liquid crystal in which a chiral agent is added to a liquid crystal, the liquid crystal is substantially vertically aligned when no nematic liquid crystal voltage is applied, and is twisted multi-domain aligned when a voltage is applied. It may be a cell.

  The in-plane switching (IPS) mode liquid crystal cell is a so-called sandwich cell in which a liquid crystal is sealed between two parallel substrates using a voltage-controlled birefringence (ECB) effect. This means that nematic liquid crystal aligned in a homogeneous molecular arrangement in a non-existing state responds with an electric field (also referred to as a transverse electric field) parallel to the substrate. Specifically, Techno Times Publishing “Monthly Display July” p. 83-p. 88 (1997 edition) and “Liquid Crystal vol. 2 No. 4” published by the Japanese Liquid Crystal Society. 303-p. 316 (1998 edition), when the upper and lower polarizing plates are arranged orthogonally so that the major axis of the liquid crystal molecules and the polarizing axis of the incident side polarizing plate coincide with each other, the display is completely black without an electric field. When there is an electric field, the liquid crystal molecules are those that can obtain transmittance according to the rotation angle by rotating while keeping parallel to the substrate.

  The above-mentioned bend nematic (OCB: Optically Compensated Bend or Optically Compensated Birefringence) mode liquid crystal cell uses a voltage-controlled birefringence effect, and a nematic liquid crystal having a positive dielectric anisotropy between transparent electrodes when no voltage is applied. The liquid crystal cell is a bend-aligned liquid crystal cell having a twisted alignment in the center. The OCB mode liquid crystal cell is also referred to as a “π cell”. Specific examples include those described in Kyoritsu Publishing Co., Ltd. “Next Generation Liquid Crystal Display” (2000), pages 11 to 27, and those described in JP-A-7-084254.

<< H. Other retardation film >>
In the present invention, as the other retardation film, an appropriate one can be adopted according to the driving mode of the liquid crystal cell. Depending on the driving mode of the liquid crystal cell, the other retardation film may be omitted or may be replaced with an isotropic film. Referring to FIGS. 6 and 7, another retardation film 70 is disposed between the liquid crystal cell 100 and the second polarizer 60. According to such an embodiment, the other retardation film 70 also serves as a protective layer on the liquid crystal cell side of the second polarizer 60, which can contribute to the thinning of the liquid crystal panel. The place where the other retardation film 70 is arranged is not limited to the illustrated example, and may be between the liquid crystal cell 100 and the positive C plate 50. Further, they may be arranged on both sides of the liquid crystal cell 100, respectively. In the illustrated example, only one other retardation film 70 is disposed between the liquid crystal cell 100 and the polarizer 60, but this may be two or both sides of the liquid crystal cell. In addition, one or more other retardation films may be disposed respectively. When two or more other retardation films are used, each retardation film may be the same or different.

  Preferably, the other retardation film 70 is used to optically compensate and cancel the retardation value of the liquid crystal cell 100. FIG. 8 is a typical conceptual diagram for explaining a method of canceling the retardation value of the liquid crystal cell using another retardation film. In this specification, “cancel a liquid crystal cell” means that a laminate of a liquid crystal cell and another retardation film has an isotropic refractive index distribution substantially having a relationship of nx = ny = nz. Thus, it means to compensate optically. As shown in FIG. 8, for example, a phase difference value of a liquid crystal cell having a refractive index distribution of nz> nx = ny (typically, a liquid crystal cell having a drive mode of TN mode, OCB mode, and HAN mode). In order to cancel the above, preferably, another retardation film having a refractive index distribution of nx = ny> nz is disposed so that the slow axes of the liquid crystal cell and the other retardation film are orthogonal to each other. . For the sake of simplicity, the illustrated example shows only the case of a liquid crystal cell in which the refractive index distribution has a relationship of nz> nx = ny, but the liquid crystal cell in which the refractive index distribution has a relationship of nz> nx> ny, It goes without saying that the present invention can also be applied to a liquid crystal cell having a relationship of nx> ny = nz with a refractive index distribution using another retardation film having an appropriate refractive index distribution.

  Any appropriate material can be selected as the material for forming the other retardation film. Preferably, those excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like are preferably used. Specific examples include a stretched polymer film mainly composed of a thermoplastic resin and an optical film in which a liquid crystal compound is oriented in an arbitrary arrangement and solidified or cured. In addition, an appropriate value is set as the retardation value of the other retardation film according to the refractive index distribution of the liquid crystal cell (resulting in the retardation value).

<< I. Embodiment of Liquid Crystal Display Device of the Present Invention >>
FIG. 9 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. The liquid crystal display device 200 includes a liquid crystal panel 150, protective layers 110 and 111 disposed on both sides of the liquid crystal panel, surface treatment layers 120 and 121 disposed further outside the protective layers 110 and 111, and a surface treatment layer. The brightness enhancement film 130, the prism sheet 140, the light guide plate 160, and the backlight 170 disposed on the outside (backlight side) 121 are provided. As the surface treatment layers 120 and 121, treatment layers subjected to hard coat treatment, antireflection treatment, antisticking treatment, diffusion treatment (also referred to as antiglare treatment), and the like are used. Further, as the brightness enhancement film 130, a polarized light separation film having a polarization selective layer (eg, trade name “D-BEF series” manufactured by Sumitomo 3M Co., Ltd.) is used. By using these optical members, a display device with higher display characteristics can be obtained. In another embodiment, the optical member illustrated in FIG. 9 may be partially omitted depending on the driving mode and application of the liquid crystal cell to be used as long as the present invention is satisfied. The optical member can be replaced.

  Preferably, in the liquid crystal display device provided with the liquid crystal panel of the present invention, the contrast ratio (YW / YB) in the azimuth angle 45 ° direction and the polar angle 60 ° direction is 10 or more, more preferably 12 or more, particularly preferably 20 or more. Most preferably, it is 50 or more.

  More preferably, in the liquid crystal display device including the liquid crystal panel of the present invention, the contrast ratio in the oblique direction is in the above range, and the color shift amount in the azimuth angle 45 ° direction and polar angle 60 ° direction (Δxy value) is 1 or less, more preferably 0.7 or less, particularly preferably 0.6 or less, and most preferably 0.5 or less.

<< J. Application of liquid crystal panel and liquid crystal display device of the present invention >>
The use in which the liquid crystal panel and the liquid crystal display device of the present invention are used is not particularly limited, but is an OA device such as a personal computer monitor, a notebook personal computer, a copy machine, a mobile phone, a watch, a personal digital assistant (PDA), a portable game machine, etc. Portable devices, home appliances such as video cameras, LCD TVs, microwave ovens, back monitors, car navigation system monitors, car audio and other in-car devices, commercial store information monitors, display equipment, surveillance monitors It can be used for various applications such as nursing equipment and medical equipment such as security equipment such as nursing monitors and medical monitors.

  Particularly preferably, the liquid crystal panel and the liquid crystal display device of the present invention are used for a large-sized liquid crystal television. The screen size of the liquid crystal television in which the liquid crystal panel and the liquid crystal display device of the present invention are used is preferably a wide 17 type (373 mm × 224 mm) or more, more preferably a wide 23 type (499 mm × 300 mm) or more, particularly Preferably, it is wide 26 type (566 mm × 339 mm) or more, and most preferably wide 32 type (687 mm × 412 mm) or more.

The present invention will be further described using the following examples and comparative examples. In addition, this invention is not limited only to these Examples. In addition, each analysis method used in the Example is as follows.
(1) Measuring method of single transmittance and polarization degree of polarizer:
It measured at 23 degreeC using the spectrophotometer [Murakami Color Research Laboratory Co., Ltd. product name "DOT-3"].
(2) Measuring method of molecular weight:
Polystyrene was calculated as a standard sample by the gel permeation chromatograph (GPC) method. Specifically, it measured with the following apparatuses, instruments, and measurement conditions.
・ Analyzer: “HLC-8120GPC” manufactured by TOSOH
Column: TSKgel Super HM-H / H4000 / H3000 / H2000
Column size: 6.0 mmI. D. × 150mm
-Eluent: Tetrahydrofuran-Flow rate: 0.6 ml / min.
・ Detector: RI
-Column temperature: 40 ° C
・ Injection volume: 20 μl
(3) Measuring method of thickness:
When the thickness was less than 10 μm, measurement was performed using a thin film spectrophotometer [manufactured by Otsuka Electronics Co., Ltd., “instant multiphotometry system MCPD-2000”]. When the thickness was 10 μm or more, measurement was performed using an Anritsu digital micrometer “KC-351C type”.
(4) Measuring method of phase difference values (Re, Rth):
It measured with the light of wavelength 590nm in 23 degreeC using the phase difference meter [Oji Scientific Instruments Co., Ltd. product name "KOBRA21-ADH"] based on a parallel Nicol rotation method. For wavelength dispersion measurement, light having a wavelength of 480 nm was also used.
(5) Method for measuring refractive index of film:
It calculated | required from the refractive index measured with the light of wavelength 589nm in 23 degreeC using the Abbe refractometer [The product name "DR-M4" by Atago Co., Ltd.].
(6) Transmittance measurement method:
It measured with the light of wavelength 590nm in 23 degreeC using the ultraviolet visible spectrophotometer [The product name "V-560" by JASCO Corporation].
(7) Photoelastic coefficient measurement method:
Using a spectroscopic ellipsometer [product name “M-220” manufactured by JASCO Corporation], the sample (size 2 cm × 10 cm) is sandwiched at both ends and stress (5 to 15 N) is applied to the phase difference at the center of the sample. The value (23 ° C./wavelength 590 nm) was measured and calculated from the slope of the function of stress and retardation value.
(8) UV irradiation method:
An ultraviolet irradiation device using a metal halide lamp having a light intensity of a wavelength of 365 nm of 120 mW / cm ² as a light source was used.
(9-1) Measuring method of contrast ratio of liquid crystal display device:
The measurement was performed after a predetermined time had elapsed since the backlight was turned on in a dark room at 23 ° C. using the following method and measurement apparatus. A white image and a black image were displayed on the liquid crystal display device, and the Y value of the XYZ display system in the azimuth angle 45 ° direction and polar angle 60 ° direction of the display screen was measured by a product name “EZ Contrast 160D” manufactured by ELDIM. Then, the contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) in the white image and the Y value (YB) in the black image. An azimuth angle of 45 ° represents an azimuth rotated 45 ° counterclockwise when the long side of the panel is 0 °, and a polar angle of 60 ° is when the front direction of the display screen is 0 °. Represents a direction inclined at an angle of 60 °.
(9-2) Measuring method of light leakage amount of liquid crystal display device:
After 30 minutes have passed since the light was turned on in a dark room at 23 ° C., an ELDIM product name “EZ Contrast 160D” was used to display a black image at an azimuth angle of 0 ° to 360 ° and a polar angle of 60 °. The tristimulus value Y value defined by the CIE1931XYZ display system was measured.
(10-1) Measuring method of color shift amount (Δxy value) of liquid crystal display device:
The measurement was performed after a predetermined time had elapsed since the backlight was turned on in a dark room at 23 ° C. using the following method and measurement apparatus. A black image was displayed on the liquid crystal display device, and the x and y values of the XYZ color system in the azimuth angle 45 ° direction and polar angle 60 ° direction were measured using a product name “EZ Contrast 160D” manufactured by ELDIM. The color shift amount (Δxy value) in the oblique direction was calculated from the formula: {(x−0.31) ² + (y−0.31) ² } ^1/2 . Note that the azimuth angle 45 ° represents an azimuth rotated 45 ° counterclockwise when the long side of the panel is 0 °. Further, the polar angle of 60 ° represents an orientation viewed obliquely by 60 ° when the vertical direction is 0 ° with respect to the panel.
(10-2) Measuring method of color shift amount (ΔE) of liquid crystal display device:
The measurement was performed after a predetermined time (30 minutes in this specification) had elapsed since the backlight was turned on in a dark room at 23 ° C. A black image is displayed on the liquid crystal display device, and the product name “EZ Contrast 160D” manufactured by ELDIM is used to define the CIE 1976 L ^* a ^* b ^* color space in an azimuth angle of 0 ° to 360 ° and a polar angle of 60 °. Luminance L ^* and color coordinates a ^* and b ^* were measured. The diagonal color shift amount (ΔE) was calculated from the formula: {(L ^* ) ² + (a ^* ) ² + (b ^* ) ² } ^1/2 .

<< Production of retardation film used for negative C plate >>
[Reference Example 1]
A polymer film [Fuji Photo Film Co., Ltd., trade name “Fujitack UZ” (average refractive index 1.48)] having a thickness of 80 μm as a main component was used as a retardation film A-1. The characteristics of the retardation film A-1 are shown in Table 1 together with the film characteristics of Reference Examples 2 to 4 described later.

[Reference Example 2]
Calamitic liquid crystal compound having two polysynthetic functional groups in a part of the molecular structure [trade name “Paliocolor LC242” (ne = 1.654, no = 1.523) made by BASF] 90 parts by weight, polymerizable chiral agent [BASF Product name “Paliocolor LC756” 10 parts by weight, photopolymerization initiator [Ciba Specialty Chemicals Co., Ltd. product name “Irgacure 907”] 5 parts by weight is dissolved in cyclopentanone 300 parts by weight, and the total solid concentration is 26. A solution of a liquid crystal composition by weight% was prepared. Using a rod coater, this liquid crystal composition solution was uniformly applied to the surface of a commercially available polyethylene terephthalate film [trade name “Lumirror S27-E” (thickness 75 μm) manufactured by Toray Industries, Inc.], and 70 ° C. A solidified layer of a liquid crystal composition containing a planarly aligned liquid crystal compound was obtained by drying in an air circulation type constant temperature oven at ± 1 ° C. for 5 minutes. Subsequently, the solidified layer was irradiated with ultraviolet rays having an irradiation light amount of 600 mJ / cm ² (in an air atmosphere) to cure the liquid crystalline composition by a polymerization reaction. The polyethylene terephthalate film was peeled off, and a cured layer of a liquid crystalline composition containing a liquid crystal compound having a planar orientation of 1.5 μm in thickness was obtained. This cured layer is referred to as retardation film A-2, and the characteristics are as shown in Table 1.

[Reference Example 3]
2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropanoic dianhydride (20 mmol) and 2,2-bis (trifluoromethyl) -4,4′-diaminobiphenyl (20 mmol) 17.7 parts by weight of polyimide (weight average molecular weight 124,000, average refractive index 1.55, imidization rate 99%) obtained by a conventional method is dissolved in 100 parts by weight of methyl isobutyl ketone to obtain a total solid content. A polyimide solution having a concentration of 15% by weight was prepared. This polyimide solution was uniformly coated on the surface of a commercially available polyethylene terephthalate film [trade name “Lumirror S27-E” (thickness 75 μm) manufactured by Toray Industries, Inc.] using a rod coater, and the temperature was 135 ° C. ± 1 ° C. The solvent was evaporated by drying in an air circulating thermostatic oven for 5 minutes and then in an air circulating thermostatic oven at 150 ° C. ± 1 ° C. for 10 minutes. The polyethylene terephthalate film was peeled off to obtain a polymer film (residual volatile component amount 2%) mainly composed of polyimide having a thickness of 3.8 μm. This polymer film is referred to as retardation film A-3, and the characteristics are shown in Table 1.

[Reference Example 4]
A polymer film [trade name “Fujitack UZ” (average refractive index: 1.48) manufactured by Fuji Photo Film Co., Ltd.] having a thickness of 40 μm as a main component and made of triacetylcellulose was used as a retardation film A-4. The characteristics are shown in Table 1.

<< Production of retardation film used for positive A plate >>
[Reference Example 5]
Cycloolefin resin hydrogenated from a ring-opening polymer of a norbornene monomer [trade name “Arton” (glass transition temperature 171 ° C., weight average molecular weight 130,000) manufactured by JSR Corporation] and styrene / anhydrous 30 parts by weight of maleic acid copolymer [manufactured by Sigma-Aldrich Japan Co., Ltd. (glass transition temperature 120 ° C., weight average molecular weight (224,000))] is dissolved in 300 parts by weight of toluene, and the total solid concentration is 25% by weight. % Resin composition solution was prepared. Using a rod coater, this solution was uniformly applied to the surface of a commercially available polyethylene terephthalate film [trade name “Lumirror S27-E” (thickness 75 μm) manufactured by Toray Industries, Inc.], and air at 135 ° C. ± 1 ° C. The solvent was evaporated by drying in a circulating thermostatic oven for 5 minutes and then in an air circulating thermostatic oven at 150 ° C. ± 1 ° C. for 10 minutes. The above-mentioned polyethylene terephthalate film is peeled off, and a high resin composition comprising as a main component a mixture of a styrene / maleic anhydride copolymer having a thickness of 83 μm and a cycloolefin resin obtained by hydrogenating a ring-opening polymer of a norbornene monomer. A molecular film (Re [590] 3 nm, Rth [590] 4 nm, average refractive index 1.52) was obtained. This polymer film was stretched 1.2 times in one direction (longitudinal uniaxial stretching) in a 120 ° C. ± 1 ° C. air circulating constant temperature oven using a biaxial stretching machine while fixing only the longitudinal direction. The obtained stretched film is referred to as a retardation film B-1, and the characteristics thereof are shown in Table 2 together with the film characteristics of Reference Examples 6 to 10 described later.

[Reference Example 6]
A retardation film B-2 was produced in the same manner as in Reference Example 5, except that the draw ratio was 1.35 times. Table 2 shows the properties of the retardation film B-2.

[Reference Example 7]
A retardation film B-3 was produced in the same manner as in Reference Example 5 except that the stretching temperature was 150 ° C. and the stretching ratio was 1.5 times. Table 2 shows the properties of the retardation film B-3.

[Reference Example 8]
A resin film [trade name “Zeonor ZF14” (thickness: 60 μm, Tg = 136 ° C.) manufactured by Optes Co., Ltd.] obtained by hydrogenation of a ring-opening polymer of a norbornene-based monomer, is circulated at 140 ° C. with a roll stretching machine. In the oven, the film was stretched 1.19 times in the longitudinal direction to prepare a retardation film B-4. Table 2 shows the properties of the retardation film B-4.

[Reference Example 9]
A retardation film B-5 was produced in the same manner as in Reference Example 8 except that the draw ratio was 1.24. Table 2 shows the properties of the retardation film B-5.

[Reference Example 10]
A retardation film B-6 was produced in the same manner as in Reference Example 8 except that the draw ratio was 1.27. Table 2 shows the properties of the retardation film B-6.

<< Production of retardation film used for positive C plate >>
[Reference Example 11]
Commercially available polyethylene terephthalate film [trade name “S-27E” manufactured by Toray Industries, Inc. (thickness: 75 μm)] and ethyl silicate solution [manufactured by Colcoat Co., Ltd. (mixed solution of ethyl acetate and isopropyl alcohol, 2 wt%)] is gravure It was coated with a coater and dried in an air circulation type constant temperature oven at 130 ° C. ± 1 ° C. for 1 minute to form a glassy polymer film having a thickness of 0.1 μm on the surface of the polyethylene terephthalate film.

Next, 5 parts by weight of a polymer liquid crystal (weight average molecular weight: 5,000) represented by the following formula (II) and a calamitic liquid crystal compound having two polysynthetic functional groups in a part of the molecular structure [manufactured by BSAF, product 20 parts by weight of the name “Pariocolor LC242” (ne = 1.654, no = 1.523)] and 1.25 parts by weight of a photopolymerization initiator [Ciba Specialty Chemicals, Inc., trade name “Irgacure 907”] A solution of the liquid crystalline composition was prepared by dissolving in 75 parts by weight of cyclohexanone. This solution was coated on the glassy polymer film of the polyethylene terephthalate film using a rod coater, dried for 2 minutes in an air circulating constant temperature oven at 80 ° C. ± 1 ° C., and then brought to room temperature (23 ° C.). Then, a solidified layer of a liquid crystalline composition having homeotropic alignment was formed on the surface of the polyethylene terephthalate film. Next, the solidified layer was irradiated with ultraviolet rays having an irradiation light amount of 400 mJ / cm ^{2 in} an air atmosphere to cure the liquid crystalline composition by a polymerization reaction. The polyethylene terephthalate film was peeled off, and a cured layer of a liquid crystalline composition having a thickness of 0.5 μm and homeotropically aligned was obtained. The said hardened layer is made into retardation film C-1, and the characteristic is shown in Table 3 together with the film characteristic of the below-mentioned reference examples 12-17.

[Reference Example 12]
A retardation film C-2 was produced in the same manner as in Reference Example 11 except that the coating thickness of the liquid crystal composition solution was changed. Table 3 shows the properties of the retardation film C-2.

[Reference Example 13]
A retardation film C-3 was produced in the same manner as in Reference Example 11 except that the coating thickness of the liquid crystal composition solution was changed. Table 3 shows the properties of the retardation film C-3.

[Reference Example 14]
A retardation film C-4 was produced in the same manner as in Reference Example 11 except that the coating thickness of the liquid crystal composition solution was changed. Table 3 shows the properties of the retardation film C-4.

[Reference Example 15]
A liquid crystal composition solution was prepared in the same manner as in Reference Example 11. This solution was applied on the surface of a polymer film mainly composed of a commercially available norbornene meter resin [trade name “Zeonor ZF14” (thickness: 100 μm) manufactured by Optes Co., Ltd.] using a die coater, and 80 ° C. ± 1 After drying for 2 minutes in an air circulation oven at 0 ° C., the solution was gradually cooled to room temperature (23 ° C.) to form a solidified layer of a liquid crystal composition having homeotropic alignment on the surface of the polymer film. Next, the solidified layer was irradiated with ultraviolet rays having an irradiation light amount of 400 mJ / cm ^{2 in} an air atmosphere to cure the liquid crystalline composition by a polymerization reaction. The polymer film was peeled off to obtain a cured layer of a liquid crystalline composition containing a homeotropically oriented calamitic liquid crystal compound. This cured layer was designated as retardation film C-5. Table 3 shows the properties of the retardation film C-5.

[Reference Example 16]
A retardation film C-6 was produced in the same manner as in Reference Example 15 except that the coating thickness of the liquid crystal composition solution was changed. Table 3 shows the properties of the retardation film C-6.

[Reference Example 17]
A retardation film C-7 was produced in the same manner as in Reference Example 15 except that the coating thickness of the liquid crystal composition solution was changed. Table 3 shows the properties of the retardation film C-7.

<< Production of isotropic film >>
[Reference Example 18]
Alternating copolymer consisting of isobutylene and N-methylmaleimide (N-methylmaleimide content 50% mol, glass transition temperature 157 ° C.) 65 parts by weight, acrylonitrile / styrene copolymer (acrylonitrile content 27% mol) 35 Parts by weight and 1 part by weight of 2- [4,6-diphenyl-1,3,5-triazin-2-yl] -5-[(hexyl) oxy] -phenol (ultraviolet absorber) in an extruder After being dried at 100 ° C. for 5 hours, it was extruded at 270 ° C. using a 40 nm φm single screw extruder and a 400 mm wide T-die, and the sheet-like molten resin was cooled with a cooling drum to a width of about 600 mm, thickness A 40 μm transparent polymer film X was produced. The polymer film X had Re [590] 1 nm, Rth [590] 2 nm, a transmittance of 90%, and an absolute value of photoelastic coefficient of 5.1 × 10 ⁻¹² (m ² / N).

[Reference Example 19]
A polymer film mainly composed of a commercially available cellulose resin [trade name “Fujitack ZRF80S” manufactured by Fuji Photo Film Co., Ltd.] was used as the optical film Y as it was. The optical film Y had Re [590] = 0 nm and Rth [590] = 2 nm, and was substantially optically isotropic.

<Production of polarizer>
[Reference Example 20]
Polymer film containing polyvinyl alcohol as a main component [trade name “9P75R (thickness: 75 μm, average degree of polymerization: 2,400, degree of saponification 99.9 mol%) manufactured by Kuraray Co., Ltd.]” is 30 ° C. ± 3 ° C. In a dyeing bath containing iodine and potassium iodide held in a roll, the film was uniaxially stretched 2.5 times while dyeing using a roll stretching machine. Subsequently, it was uniaxially stretched so as to be 6 times the original length of the polyvinyl alcohol film while performing a crosslinking reaction in an aqueous solution containing boric acid and potassium iodide maintained at 60 ± 3 ° C. The obtained film was dried in an air-circulating constant temperature oven at 50 ° C. ± 1 ° C. for 30 minutes to obtain a polarizer P1 having a moisture content of 23%, a thickness of 28 μm, a degree of polarization of 99.9%, and a unit transmittance of 43.5%. , P2 was obtained.

<< Production of other polarizing elements >>
[Reference Example 21]
It is obtained in Reference Example 18 through an adhesive layer made of an isocyanate-based adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.] on both surfaces of the polarizer P2 obtained in Reference Example 20. The polymer film X was laminated to produce a polarizing element (X).

[Reference Example 22]
It is obtained in Reference Example 19 via an adhesive layer made of an isocyanate adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.] on both surfaces of the polarizer P2 obtained in Reference Example 20. The polarizing film (Y) was produced by laminating the optical film Y.

<< Production of IPS mode liquid crystal cell >>
[Reference Example 23]
Take out the liquid crystal panel from the liquid crystal display device [SONY KLV-17HR2] including the liquid crystal cell of IPS mode, remove all the optical films placed above and below the liquid crystal cell, and clean the glass surface (front and back) of the liquid crystal cell did. The liquid crystal cell thus prepared was designated as liquid crystal cell A.

[Reference Example 24]
Take out the liquid crystal panel from the liquid crystal display device including the IPS mode liquid crystal cell [32V type wide liquid crystal television manufactured by Toshiba Corporation, product name “FACE” (model number: 32LC100, screen size: 697 mm × 392 mm)], and place it above and below the liquid crystal cell. All the arranged optical films were removed, and the glass surfaces (front and back) of the liquid crystal cell were washed. The liquid crystal cell thus produced was designated as liquid crystal cell B.

[Example 1]
A reference example is formed on the surface of one side of the polarizer P1 obtained in Reference Example 20 via an adhesive layer made of an isocyanate adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.]. The polymer film X obtained in 18 was laminated. Next, a retardation film A- is formed on the other surface of the polarizer P1 through an adhesive layer made of an isocyanate adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.]. 1 (negative C plate) was laminated such that its slow axis was substantially parallel (0 ° ± 0.5 °) with the absorption axis of the polarizer P1. Further, the retardation film B-2 (positive A plate) is bonded to the surface of the retardation film A-1 via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the slow axis of the retardation film B-2 is the polarizer. The layers were laminated so as to be substantially orthogonal (90 ° ± 0.5 °) to the absorption axis of P1. Furthermore, the retardation film C-2 (positive C plate) is attached to the surface of the retardation film B-2 via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the slow axis thereof is the polarizer. The polarizing element (i) was produced by laminating so as to be substantially parallel to the absorption axis of P1 (0 ° ± 0.5 °).

  Next, the polarizing element (i) is placed on the viewing side of the IPS mode liquid crystal cell A obtained in Reference Example 23 via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the absorption axis of the polarizer P1. However, they were laminated so that they were substantially parallel to the long side of the liquid crystal cell (0 ° ± 0.5 °) and each retardation film was opposed to the liquid crystal cell. At this time, the absorption axis of the polarizer P1 is substantially orthogonal to the initial alignment direction of the liquid crystal cell. Further, the polarizing element (X) obtained in Reference Example 21 is connected to the backlight side of the IPS mode liquid crystal cell through an adhesive layer made of an acrylic adhesive having a thickness of 20 μm so that the absorption axis of the polarizer P2 is The liquid crystal cell was laminated so as to be substantially parallel to the short side (0 ° ± 0.5 °). At this time, the absorption axes of the polarizers P1 and P2 are orthogonal.

  The liquid crystal panel (i) thus obtained has the configuration shown in FIG. This liquid crystal panel (i) was combined with a backlight unit to produce a liquid crystal display device (i). The contrast ratio in the oblique direction and the amount of color shift in the oblique direction were measured 30 minutes after the backlight was turned on. The obtained characteristics are shown in Table 4 together with the data of Examples 2 to 4 and Comparative Examples 1 and 2.

[Example 2]
A liquid crystal panel (ii) and a liquid crystal display device (ii) were prepared in the same manner as in Example 1 except that the retardation film A-2 was used as the negative C plate and the retardation film B-1 was used as the positive A plate. Was made. Table 4 shows the characteristics of the liquid crystal display device (ii).

[Example 3]
A reference example is formed on the surface of one side of the polarizer P1 obtained in Reference Example 20 via an adhesive layer made of an isocyanate adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.]. The polymer film X obtained in 18 was laminated. Next, a retardation film B- is formed on the other surface of the polarizer P1 through an adhesive layer made of an isocyanate adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.]. 3 (positive A plate) were laminated so that the slow axis thereof was substantially orthogonal (90 ° ± 0.5 °) to the absorption axis of the polarizer P1. Further, the retardation film C-3 (positive C plate) is disposed on the surface of the retardation film B-3 via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the slow axis thereof is the polarizer. The layers were laminated so as to be substantially parallel to the absorption axis of P1 (0 ° ± 0.5 °). Further, the retardation film A-1 (negative C plate) is disposed on the surface of the retardation film C-3 via an adhesive layer made of an acrylic pressure-sensitive adhesive having a thickness of 20 μm, and the slow axis thereof is the polarizer. The polarizing element (iii) was produced by laminating so as to be substantially parallel (0 ° ± 0.5 °) with the absorption axis of P1.

  Next, the polarizing element (iii) is placed on the viewing side of the IPS mode liquid crystal cell obtained in Reference Example 23 with an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the absorption axis of the polarizer P1 is The liquid crystal cell was laminated so that it was substantially parallel to the long side (0 ° ± 0.5 °) and each retardation film was opposed to the liquid crystal cell. In addition, the polarizing element (X) obtained in Reference Example 21 is connected to the backlight side of the IPS mode liquid crystal cell through an adhesive layer made of an acrylic adhesive having a thickness of 20 μm so that the absorption axis of the polarizer P2 is The liquid crystal cell was laminated so as to be substantially parallel to the short side (0 ° ± 0.5 °). At this time, the absorption axes of the polarizers P1 and P2 are orthogonal.

  The liquid crystal panel (iii) thus obtained has the configuration shown in FIG. This liquid crystal panel (iii) was combined with a backlight unit to produce a liquid crystal display device (iii). Table 4 shows the characteristics of the liquid crystal display device (iii).

[Example 4]
A liquid crystal panel (iv) and a liquid crystal display device (iv) were prepared in the same manner as in Example 3 except that the retardation film A-3 was used as the negative C plate and the retardation film C-4 was used as the positive C plate. Was made. Table 4 shows the characteristics of the liquid crystal display device (iv).

[Comparative Example 1]
A liquid crystal panel (p) and a liquid crystal display device (p) were produced in the same manner as in Example 1 except that the retardation film C-1 was used as the positive C plate. Table 4 shows the characteristics of the liquid crystal display device (p).

[Comparative Example 2]
A liquid crystal panel (q) and a liquid crystal display device (q) were produced in the same manner as in Example 3 except that the retardation film C-1 was used as the positive C plate. Table 4 shows the characteristics of the liquid crystal display device (q).

[Example 5]
A reference example is formed on the surface of one side of the polarizer P1 obtained in Reference Example 20 via an adhesive layer made of an isocyanate adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.]. The polymer film Y obtained in 19 was laminated. Next, a retardation film A- is formed on the other surface of the polarizer P1 through an adhesive layer made of an isocyanate adhesive having a thickness of 5 μm [trade name “Takenate 631” manufactured by Mitsui Takeda Chemical Co., Ltd.]. 4 (negative C plate) were laminated so that the slow axis thereof was substantially parallel to the absorption axis of the polarizer P1 (0 ° ± 0.5 °). Further, the retardation film B-4 (positive A plate) is attached to the surface of the retardation film A-4 via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the slow axis thereof is the polarizer. The layers were laminated so as to be substantially orthogonal (90 ° ± 0.5 °) to the absorption axis of P1. Furthermore, the retardation film C-5 (positive C plate) is bonded to the surface of the retardation film B-4 via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the slow axis of the retardation film C-5 is the polarizer. The polarizing element (v) was manufactured by laminating so as to be substantially parallel to the absorption axis of P1 (0 ° ± 0.5 °).

  Next, the polarizing element (i) is placed on the viewing side of the IPS mode liquid crystal cell B obtained in Reference Example 24 via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm, and the absorption axis of the polarizer P1. However, they were laminated so that they were substantially parallel to the long side of the liquid crystal cell (0 ° ± 0.5 °) and each retardation film was opposed to the liquid crystal cell. At this time, the absorption axis of the polarizer P1 is substantially orthogonal to the initial alignment direction of the liquid crystal cell. In addition, the polarizing element (Y) obtained in Reference Example 22 is connected to the backlight side of the IPS mode liquid crystal cell via an adhesive layer made of an acrylic adhesive having a thickness of 20 μm so that the absorption axis of the polarizer P2 is The liquid crystal cell was laminated so as to be substantially parallel to the short side (0 ° ± 0.5 °). At this time, the absorption axes of the polarizers P1 and P2 are orthogonal.

  The liquid crystal panel (v) thus obtained has the configuration shown in FIG. This liquid crystal panel (v) was combined with a backlight unit to produce a liquid crystal display device (v). The contrast ratio in the oblique direction and the amount of color shift in the oblique direction were measured 30 minutes after the backlight was turned on. The obtained characteristics are shown in Table 5 together with the data of Examples 6 to 11.

[Example 6]
A liquid crystal panel (vi) and a liquid crystal display device (vi) were produced in the same manner as in Example 5 except that the retardation film B-5 was used as the positive A plate. Table 5 shows the characteristics of the liquid crystal display device (vi). Furthermore, the luminance contour map of this liquid crystal display device is shown in FIG.

[Example 7]
A liquid crystal panel (vii) and a liquid crystal display device (vii) were produced in the same manner as in Example 5 except that the retardation film C-6 was used as the positive C plate. Table 5 shows the characteristics of the liquid crystal display device (vii).

[Example 8]
A liquid crystal panel (viii) and a liquid crystal display device (viii) were prepared in the same manner as in Example 5 except that the retardation film B-5 was used as the positive A plate and the retardation film C-6 was used as the positive C plate. Was made. Table 5 shows the characteristics of the liquid crystal display device (viii). Further, FIG. 11 shows a luminance contour map of this liquid crystal display device.

[Example 9]
A liquid crystal panel (ix) and a liquid crystal display device (ix) were prepared in the same manner as in Example 5 except that the retardation film B-6 was used as the positive A plate and the retardation film C-6 was used as the positive C plate. Was made. Table 5 shows the characteristics of the liquid crystal display device (ix).

[Example 10]
A liquid crystal panel (x) and a liquid crystal display device (x) were produced in the same manner as in Example 5 except that the retardation film C-7 was used as the positive C plate. Table 5 shows the characteristics of the liquid crystal display device (x).

[Example 11]
A liquid crystal panel (xi) and a liquid crystal display device (xi) were prepared in the same manner as in Example 5 except that the retardation film B-5 was used as the positive A plate and the retardation film C-7 was used as the positive C plate. Was made. Table 5 shows the characteristics of the liquid crystal display device (xi).

[Evaluation]
As shown in Examples 1 to 4, a liquid crystal panel (as a result, a liquid crystal display device) including the polarizing element of the present invention has an excellent contrast ratio in an oblique direction and an excellent small color shift amount (Δxy) in an oblique direction. Display characteristics were shown. On the other hand, as shown in Comparative Examples 1 and 2, a liquid crystal display device using a polarizing element in which Rth [590] of the retardation film used for the positive C plate exceeds −60 nm has a low contrast ratio in the oblique direction, and is practical. Did not satisfy the required level. Furthermore, as shown in Table 5 (Examples 5 to 11), the liquid crystal panel (as a result, the liquid crystal display device) including the polarizing element of the present invention has both the average value and the maximum value of the light leakage amount in the oblique direction. The color shift amount (ΔE) in the oblique direction was also very good. In addition, it is also clear from FIGS. 10 and 11 that the light leakage in the oblique direction in the liquid crystal panel (resulting in the liquid crystal display device) including the polarizing element of the present invention is small.

  As described above, the polarizing element of the present invention can increase the contrast ratio in the oblique direction and reduce the color shift amount in the oblique direction by being arranged on at least one side of the liquid crystal cell. It can be said that it is extremely useful for improving the characteristics. The polarizing element of the present invention is suitably used for a liquid crystal display device and a liquid crystal television.

It is a schematic sectional drawing of the polarizing element by preferable embodiment of this invention. It is a schematic perspective view of the polarizing element of FIG. It is a schematic diagram which shows the concept of the typical manufacturing process of the polarizer used for this invention. (A) is a schematic diagram explaining the planar aligned calamitic liquid crystal compound, and (b) is a schematic diagram explaining the columnar aligned discotic liquid crystal compound. It is a schematic diagram explaining the outline | summary of the manufacturing method of the phase difference film used for a positive C plate. It is a schematic sectional drawing of the liquid crystal panel by preferable embodiment of this invention. It is a schematic perspective view of the liquid crystal panel of FIG. It is a typical conceptual diagram explaining the method of canceling the phase difference value of a liquid crystal cell using another phase difference film. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It is a brightness | luminance contour map of the liquid crystal display device of Example 6. FIG. 10 is a luminance contour map of the liquid crystal display device of Example 8;

Explanation of symbols

10, 11, 12 Polarizing element 20 Polarizer 30 Negative C plate 40 Positive A plate 50 Positive C plate 60 Second polarizer 70 Other retardation film 100 Liquid crystal cell 101, 102 Glass substrate 103 Liquid crystal layer 110, 111 Protective layer 120, 121 Surface treatment layer 130 Brightness enhancement film 140 Prism sheet 150 Liquid crystal panel 160 Light guide plate 170 Backlight 300 Feeding part 301 Polymer film 310 Iodine aqueous solution bath 320 Bath of aqueous solution containing boric acid and potassium iodide 330 Potassium iodide Aqueous solution baths 311, 312, 321, 322, 331, 332 roll 340 drying means 350 polarizer 360 take-up part 401 feed-out part 402 base material 403 guide roll 404 first coater part 405 first drying means 4 6 alignment film formed substrate 407 second coater part 408 second drying means 410 the ultraviolet irradiation unit 411 temperature controller 412 UV lamp 414 takeup unit

Claims (13)

A polarizer, and a negative C plate, a positive A plate, and a positive C plate disposed on one side of the polarizer,
The positive A plate is placed between the polarizer and the positive C plate such that its slow axis is substantially perpendicular to the absorption axis of the polarizer, and the Rth _PC [590 of the positive C plate ] Is -60 nm or less. The polarizing element according to claim 1, wherein Rth _NC [590] of the negative C plate is 30 nm to 200 nm. The polarizing element according to claim 1 or 2, wherein the sum of Rth _NC [590] of the negative C plate and Rth _PC [590] of the positive C plate is -150 nm to -30 nm.   The negative C plate includes a polymer film containing as a main component at least one thermoplastic resin selected from a cellulose resin, a polyamideimide resin, a polyether ether ketone resin, and a polyimide resin. The polarizing element according to any one of items 1 to 3. The polarizing element according to any one of claims 1 to 4, wherein Re _PA [590] of the positive A plate is 60 nm to 180 nm.   The polarizing element according to any one of claims 1 to 5, wherein the positive A plate includes a stretched film of a polymer film containing a styrene resin.   The polarizing element according to any one of claims 1 to 6, wherein the positive C plate includes a solidified layer or a cured layer of a liquid crystalline composition including a liquid crystal compound that is homeotropically aligned.   The polarizing element according to claim 7, wherein the liquid crystal composition includes a liquid crystal compound having at least one polymerizable functional group in a part of a molecular structure.   The polarizing element according to claim 7 or 8, wherein a thickness of a solidified layer or a cured layer of the liquid crystalline composition containing the homeotropically aligned liquid crystal compound is 0.6 µm to 20 µm.   A liquid crystal panel comprising the polarizing element according to claim 1 and a liquid crystal cell.   The liquid crystal panel according to claim 10, wherein the liquid crystal cell includes a liquid crystal layer including nematic liquid crystal that is homogeneously aligned in the absence of an electric field.   A liquid crystal television comprising the liquid crystal panel according to claim 10. A liquid crystal display device comprising the liquid crystal panel according to claim 10.