JP4898158B2 - Liquid crystal panel and liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal panel having a liquid crystal cell, a polarizer, and an optical element. The present invention also relates to a liquid crystal television and a liquid crystal display device using the liquid crystal panel.

  Currently, there is an in-plane switching (IPS) mode as one of driving modes of liquid crystal display devices that are widely used in television applications. In this drive mode, nematic liquid crystal aligned in a homogeneous arrangement in the absence of an electric field is driven by a lateral electric field to display an image. The IPS mode liquid crystal display device has a feature that the viewing angle is wider than that of other drive mode liquid crystal display devices, but the coloration of the image that changes with the viewing angle (also referred to as an oblique color shift). There is a problem of being big.

In order to solve this problem, an IPS mode liquid crystal display device using a polymer film (TAC layer) having a small in-plane and thickness direction retardation value as a protective layer of a polarizer is disclosed ( Patent Document 1). However, a polymer film having a small in-plane and thickness direction retardation value needs to reduce the stress applied during film forming as much as possible, and is difficult to manufacture. Furthermore, if the stress applied during film forming is reduced in order to reduce the retardation value, the direction of the slow axis of the polymer film (also referred to as the orientation angle) is likely to vary, resulting in light leakage from the liquid crystal display device. Is increased (contrast ratio is reduced and a clear image cannot be displayed). Alternatively, if the thickness is reduced in order to reduce the retardation value, the strength of the polymer film may be insufficient or the workability may deteriorate, resulting in a yield in the manufacturing process of the polarizing plate and the liquid crystal display device. Is a cause of lowering.
JP-A-10-307291

  The present invention has been made to solve such problems, and an object of the present invention is to provide a liquid crystal panel and a liquid crystal display device in which coloring of an image is small no matter what angle the screen is viewed from.

  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 following liquid crystal panel and liquid crystal display device, and have completed the present invention.

The liquid crystal panel of the present invention includes a liquid crystal cell, a first polarizer disposed on one side of the liquid crystal cell, a second polarizer disposed on the other side of the liquid crystal cell, and the first polarizer. And at least a first optical element disposed between the liquid crystal cell and
The first optical element satisfies the following formulas (1) and (2), and is arranged so that its slow axis is substantially parallel to the absorption axis of the first polarizer.
10 nm <Re [590] (1)
| Rth [590] -Re [590] | <10 nm (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  In a preferred embodiment, the liquid crystal cell includes a liquid crystal layer including liquid crystal molecules aligned in a homogeneous alignment in the absence of an electric field.

  In a preferred embodiment, the initial alignment direction of the liquid crystal cell is substantially parallel to the absorption axis of the first polarizer and the slow axis of the first optical element.

  In a preferred embodiment, the thickness of the first optical element is 50 μm to 200 μm.

  In a preferred embodiment, the first optical element includes a retardation film containing a norbornene resin and / or a retardation film containing a cellulose resin.

In a preferred embodiment, further comprising a second optical element between the liquid crystal cell and the second polarizer,
The second optical element satisfies the following formulas (3) and (4), and is arranged so that its slow axis is substantially parallel or substantially perpendicular to the absorption axis of the second polarizer. It becomes.
50 nm ≦ Rth [590] ≦ 200 nm (3)
−200 nm ≦ Rth [590] −Re [590] ≦ 80 nm (4)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  In a preferred embodiment, the second optical element includes a retardation film containing a norbornene resin and / or a retardation film containing a cellulose resin.

  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.

In the liquid crystal panel of the present invention, the first optical element having specific optical characteristics is used in a specific positional relationship between the liquid crystal cell and the polarizer disposed on one side of the liquid crystal cell, so as to be inclined. The amount of color shift in the direction can be reduced. The first optical element used in the liquid crystal panel may have large in-plane and thickness direction retardation values as long as the following expressions (1) and (2) are satisfied. Accordingly, the magnitude of the retardation value can be freely set within a realizable range. As a result, when the first optical element is used as a protective layer for a polarizer, a material excellent in cost and productivity. Can be selected. Furthermore, if a retardation film containing a norbornene resin is used for the first optical element, a variation in orientation angle and an absolute value of the photoelastic coefficient are small, so that a liquid crystal display device having good display characteristics can be obtained. . Alternatively, the thickness of the optical element can be freely set without being limited by the magnitude of the phase difference value, and as a result, the display characteristics of the liquid crystal display device can be maintained high for a long time. .
10 nm <Re [590] (1)
| Re [590] −Rth [590] | <10 nm (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively. In the present invention, the effect is particularly remarkable in a liquid crystal display device including a liquid crystal cell having a liquid crystal layer including liquid crystal molecules aligned in a homogeneous alignment in the absence of an electric field.

A. 1 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. FIG. 2A is a schematic perspective view when this liquid crystal panel adopts the E mode, and FIG. 2B is a schematic perspective view when this liquid crystal panel adopts the O mode. It should be noted that for the sake of easy understanding, the ratios of the vertical, horizontal, and thickness of each component in FIG. 1 and FIGS. 2A and 2B are described differently from the actual ones. The liquid crystal panel 100 includes a liquid crystal cell 10, a first polarizer 21 disposed on one side of the liquid crystal cell 10, a second polarizer 22 disposed on the other side of the liquid crystal cell 10, and the At least a first optical element 30 disposed between the first polarizer 11 and the liquid crystal cell is provided. The first optical element 30 satisfies the following formulas (1) and (2), and is arranged so that its slow axis is substantially parallel to the absorption axis of the first polarizer 21. .
10 nm <Re [590] (1)
| Rth [590] -Re [590] | <10 nm (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  In practice, any appropriate protective layer (not shown) may be disposed between the first polarizer 21 and the second polarizer 22. A liquid crystal display device including such a liquid crystal panel has a feature that a color shift amount in an oblique direction is remarkably small as compared with a conventional liquid crystal display device.

  The liquid crystal panel of the present invention may be a so-called E mode or a so-called O mode. The “E mode liquid crystal panel” refers to a liquid crystal panel in which the absorption axis of a polarizer disposed on the backlight side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are orthogonal to each other. The “O-mode liquid crystal panel” refers to a liquid crystal panel in which the absorption axis of a polarizer disposed on the backlight side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are parallel to each other. Referring to FIG. 2, in the case of an E mode liquid crystal panel, preferably, the first polarizer 21 and the first optical element 30 are disposed on the viewing side of the liquid crystal cell 10, and the second polarizer 22 is the liquid crystal cell 10. It can be arranged on the backlight side of. In the case of an O-mode liquid crystal panel, preferably, the first polarizer 21 and the first optical element 30 are disposed on the backlight side of the liquid crystal cell 10, and the second polarizer 22 is disposed on the viewing side of the liquid crystal cell 10. Can be done.

  The liquid crystal panel of the present invention is not limited to the above embodiment. For example, another constituent member (for example, the second optical element described later in the section E) can be disposed between the constituent members shown in FIG. Hereinafter, each member and each layer constituting the liquid crystal panel of the present invention will be described in detail.

B. Liquid Crystal Cell Referring to FIG. 1, a liquid crystal cell 10 used in the present invention includes a pair of substrates 11 and 11 ′ and a liquid crystal layer 12 as a display medium sandwiched between the substrates 11 and 11 ′. One substrate (active matrix substrate) 11 ′ includes a switching element (typically a TFT) for controlling the electro-optical characteristics 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. Are provided (both not shown). The other substrate (color filter substrate) 11 is provided with a color filter. The color filter may be provided on the active matrix substrate 11 ′. Alternatively, for example, when an RGB three-color light source is used for the backlight of the liquid crystal display device as in the field sequential method, the color filter can be omitted. A distance (cell gap) between the substrates 11 and 11 ′ is controlled by a spacer (not shown). An alignment film (not shown) made of polyimide, for example, is provided on the side of the substrates 11 and 11 ′ in contact with the liquid crystal layer 12.

  The liquid crystal layer 12 preferably includes liquid crystal molecules aligned in a homogeneous alignment in the absence of an electric field. Such a liquid crystal layer (as a result, a liquid crystal cell) typically exhibits a refractive index distribution of nx> ny = nz (where the in-plane refractive index is nx, ny, and the refractive index in the thickness direction is 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. Further, the “initial alignment direction of the liquid crystal cell” refers to a direction in which the in-plane refractive index of the liquid crystal layer that is generated as a result of alignment of liquid crystal molecules contained in the liquid crystal layer is maximized in the absence of an electric field. The initial alignment direction of the liquid crystal cell is preferably substantially parallel to the absorption axis of the first polarizer and the slow axis of the first optical element. In this specification, “substantially parallel” means that the angle formed between the initial alignment direction of the liquid crystal cell and the absorption axis of the first polarizer and the slow axis of the first optical element is 0 °. ± 2.0 ° is included, preferably 0 ° ± 1.0 °, and more preferably 0 ° ± 0.5 °.

  Typical examples of driving modes using a liquid crystal layer exhibiting a refractive index distribution of nx> ny = nz include an in-plane switching (IPS) mode, a fringe field switching (FFS) mode, and a ferroelectric liquid crystal (FLC) mode. . Specific examples of the liquid crystal used in such a drive mode include nematic liquid crystal and smectic liquid crystal. For example, a nematic liquid crystal is used for the IPS mode and the FSS mode, and a smectic liquid crystal is used for the FLC mode.

  The IPS mode uses a voltage-controlled birefringence (ECB) effect, nematic liquid crystal aligned in a homogeneous molecular arrangement in the absence of an electric field, for example, a counter electrode and a pixel electrode formed of metal. The substrate is caused to respond with an electric field (also referred to as a transverse electric field) parallel to the substrate. More specifically, for example, 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), in the normally black method, the alignment direction of the liquid crystal cell is aligned with the absorption axis of the polarizer on one side, and the upper and lower polarizing plates are arranged orthogonally. When there is no electric field, the display is completely black, and when there is an electric field, the liquid crystal molecules rotate while keeping parallel to the substrate, whereby the transmittance according to the rotation angle can be obtained. In this specification, the IPS mode is a super-in-plane switching (S-IPS) mode or an advanced super-in-plane switching (AS-IPS) mode that employs a V-shaped electrode, a zigzag electrode, or the like. Is included. As a commercially available liquid crystal display device adopting the IPS mode as described above, for example, Hitachi, Ltd. 20V wide liquid crystal television trade name “Wooo”, Eyama Corp. 19 type liquid crystal display trade name “ProLite E481S-1” ", 17 type TFT liquid crystal display manufactured by Nanao Co., Ltd., trade name" FlexScan L565 "and the like.

  The FFS mode uses a voltage-controlled birefringence (ECB) effect, and nematic liquid crystal aligned in a homogeneous molecular arrangement in the absence of an electric field, for example, with a counter electrode formed of a transparent conductor A response is generated by an electric field parallel to the substrate generated by the pixel electrode and a parabolic electric field. Note that such an electric field in the FFS mode is also referred to as a fringe electric field. This fringe electric field can be generated by setting the distance between the counter electrode made of a transparent conductor and the pixel electrode to be narrower than the distance between the upper and lower substrates. More specifically, for example, SID (Society for Information Display) 2001 Digest, p. 484-p. As described in 487 and JP 2002-031812, in the normally black method, the alignment direction of the liquid crystal cell is aligned with the absorption axis of the polarizer on one side, so that the upper and lower polarizing plates If they are arranged orthogonally, the display is completely black in the absence of an electric field, and when there is an electric field, the liquid crystal molecules can rotate while maintaining parallel to the substrate to obtain a transmittance according to the rotation angle. it can. In this specification, the FFS mode includes an advanced fringe field switching (A-FFS) mode and an ultra fringe field switching (U-FFS) mode employing a V-shaped electrode, a zigzag electrode, or the like. To do. As a commercially available liquid crystal display device that employs the FFS mode as described above, for example, “M1400”, a product name of Tablet PC manufactured by Motion Computing, Inc., may be mentioned.

  The FLC mode utilizes, for example, the property that when a ferroelectric chiral smectic liquid crystal is sealed between electrode substrates having a thickness of about 1 μm to 2 μm, it exhibits two stable molecular orientation states. The liquid crystal molecules are caused to respond by rotating in parallel with the substrate. In the FLC mode, black and white display can be obtained on the same principle as the IPS mode and the FFS mode. Furthermore, the FLC mode has a feature that the response speed is faster than other drive modes. In this specification, the FLC mode includes a surface stabilization (SS-FLC) mode, an antiferroelectric (AFLC) mode, a polymer stabilization (PS-FLC) mode, and a V-characteristic (V-FLC). ) Mode.

  The liquid crystal molecules aligned in the homogeneous alignment are those in which the alignment vector of the liquid crystal molecules is aligned in parallel and uniformly with respect to the substrate plane as a result of the interaction between the aligned substrate and the liquid crystal molecules. Say. In the present specification, “homogeneous alignment” includes a case where the alignment vector of the liquid crystal molecules is slightly tilted with respect to the plane of the substrate, that is, a case where the liquid crystal molecules have a pretilt. When the liquid crystal molecules have a pretilt, the pretilt angle is preferably 10 ° or less from the viewpoint of maintaining a high contrast ratio and obtaining good display characteristics.

As the nematic liquid crystal, any appropriate nematic liquid crystal can be adopted depending on the purpose. For example, the nematic liquid crystal may have a positive or negative dielectric anisotropy. A specific example of a nematic liquid crystal having a positive dielectric anisotropy is a product name “ZLI-4535” manufactured by Merck & Co., Inc. A specific example of a nematic liquid crystal having a negative dielectric anisotropy is a product name “ZLI-2806” manufactured by Merck & Co., Inc. Further, the difference between the ordinary light refractive index (no) and the extraordinary light refractive index (ne) of the nematic liquid crystal, that is, the birefringence (Δn _LC ) can be appropriately selected depending on the response speed, transmittance, etc. of the liquid crystal. The Δn _LC is usually 0.05 to 0.30.

Any appropriate smectic liquid crystal may be employed as the smectic liquid crystal depending on the purpose. Preferably, a smectic liquid crystal having an asymmetric carbon atom in a part of the molecular structure and exhibiting ferroelectricity (also referred to as a ferroelectric liquid crystal) is used. Specific examples of the smectic liquid crystal exhibiting ferroelectricity include p-decyloxybenzylidene-p′-amino-2-methylbutylcinnamate, p-hexyloxybenzylidene-p′-amino-2-chloropropylcinnamate, 4 -O- (2-methyl) -butylresorcylidene-4'-octylaniline and the like. Alternatively, a commercially available ferroelectric liquid crystal can be used as it is. As the commercially available ferroelectric liquid crystal, trade name ZLI-5014-000 (electric capacity 2.88 nF, spontaneous polarization −2.8 C / cm ² ) manufactured by Merck & Co., trade name ZLI-5014-100 (electric capacity) manufactured by Merck 3.19 nF, spontaneous polarization −20.0 C / cm ² ), trade name FELIX-008 (electric capacity 2.26 nF, spontaneous polarization −9.6 C / cm ² ) manufactured by Hoechst, and the like.

  Any appropriate cell gap may be adopted as the cell gap (substrate interval) of the liquid crystal cell depending on the purpose. The cell gap is preferably 1 μm to 7 μm. By setting the cell gap of the liquid crystal cell within the above range, a liquid crystal display device with a short response time can be obtained.

C. Polarizer In this specification, a polarizer refers to an element capable of converting natural light or polarized light into arbitrary polarized light. Any appropriate polarizer can be adopted as the polarizer used in the present invention. Preferably, natural light or polarized light is converted into linearly polarized light. As such a polarizer, when incident light is divided into two orthogonal polarization components, it has a function of passing one of the polarization components, and the other polarization component is absorbed and reflected. And those having at least one function selected from the function of scattering.

  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. By setting the thickness of the polarizer in the above range, a polarizing element having excellent optical characteristics and mechanical strength can be obtained.

C-1. Optical Properties of Polarizer The transmittance at a wavelength of 550 nm (also referred to as single transmittance) measured at 23 ° C. of the polarizer is preferably 41% or more, more preferably 43% or more. Note that the theoretical upper limit of the single transmittance is 50%, and the realizable upper limit is 46%. 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%. By setting the single transmittance and the polarization degree within the above ranges, a liquid crystal display device having a high contrast ratio in the front direction can be obtained.

  The hue a value (single a value) by the National Bureau of Standards (NBS) of the polarizer used in the present invention is preferably −2.0 or more and less than 0, and more preferably −1.8 or more and less than 0. . Further, the hue b value (single b value) by the National Bureau of Standards (NBS) of the polarizer is preferably more than 0 and 3.8 or less, and more preferably more than 0 and 3.5 or less. By setting the hue a value and b value of the polarizer within the above ranges, a liquid crystal display device with vivid colors of the display image can be obtained.

The single transmittance, polarization degree, and hue 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. In addition, these transmittance | permeability is Y value which performed visibility correction | amendment by the 2 degree visual field (C light source) of JlS Z 8701-1982.

C-2. Referring to FIGS. 1A and 1B, any appropriate method can be adopted as a method of arranging the first polarizer 21 and the second polarizer 22 depending on the purpose. The first polarizer 21 is preferably attached to the surface of the first optical element 30 by providing an adhesive layer (not shown) on the surface facing the liquid crystal cell 10. The second polarizer 22 is preferably attached to the surface of the liquid crystal cell 10 by providing an adhesive layer (not shown) on the surface facing the liquid crystal cell 10. In addition, when arbitrary optical elements are arrange | positioned between the liquid crystal cell 10 and the 2nd polarizer 22, the said 2nd polarizer 22 can be stuck on the surface of the said arbitrary optical elements.

  By sticking the polarizer in this way, when incorporated in a liquid crystal display device, the absorption axis of the polarizer is prevented from deviating from a predetermined position, or each optical element adjacent to the polarizer is rubbed. Can be prevented. Furthermore, since adverse effects of reflection and refraction generated at the interface between the polarizer and each adjacent optical element can be reduced, a liquid crystal display device capable of displaying a clear image can be obtained. 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 first polarizer 21 is preferably arranged so that its absorption axis is substantially perpendicular to the absorption axis of the opposing second polarizer 22. In this specification, “substantially orthogonal” includes an angle formed by the absorption axis of the first polarizer 21 and the absorption axis of the second polarizer 22 includes 90 ° ± 2.0 °, preferably It is 90 ° ± 1.0 °, and more preferably 90 ° ± 0.5 °.

  The thickness of the adhesive layer can be determined as appropriate according to the purpose of use and adhesive strength. Preferably, the thickness of the adhesive layer is 0.1 μm to 100 μm, more preferably 0.5 μm to 50 μm. By setting the thickness of the adhesive layer in the above range, the optical element and the polarizer to be joined do not float or peel off, and an adhesive force and an adhesive time that do not have a practically adverse effect can be obtained.

  As the material for forming the adhesive layer, an appropriate adhesive or anchor coating agent can be appropriately 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.

  When a polymer film containing a polyvinyl alcohol-based resin as a main component is used as a polarizer, a water-soluble adhesive is preferably used as a material for forming the adhesive layer. As said water-soluble adhesive, what has a polyvinyl alcohol-type resin as a main component is used, for example. A commercially available adhesive can be used as it is for the adhesive layer. Or a solvent and an additive can also be mixed and used for a commercially available adhesive agent. As an adhesive which has a commercially available polyvinyl alcohol-type resin as a main component, [Nippon Gosei Chemical Co., Ltd. brand name "Gosefimer Z200" is mentioned, for example.

  The water-soluble adhesive may further contain a crosslinking agent. Preferred examples of the crosslinking agent include amine compounds, aldehyde compounds, methylol compounds, epoxy compounds, isocyanate compounds, and polyvalent metal salts. A commercially available crosslinking agent can be used as it is. Commercially available cross-linking agents include amine compounds manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name “metaxylene diamine”, aldehyde compounds manufactured by Nippon Synthetic Chemical Industries, Ltd. The trade name “Watersol” and the like can be mentioned.

C-3. Optical film used for polarizer Any appropriate polarizing film is selected as the optical film used for the polarizer. The polarizer can be obtained by, for example, a stretched polymer film mainly composed of a polyvinyl alcohol resin containing iodine or a dichroic dye. Alternatively, as disclosed in US Pat. No. 5,523,863, an O-type polarizer in which a liquid crystal composition containing a dichroic substance and a liquid crystal compound is aligned in a certain direction, or US Pat. An E-type polarizer in which lyotropic liquid crystal is aligned in a certain direction as disclosed in US Pat. No. 049,428 can also be used.

  Preferably, the polarizer is a stretched film of a polymer film mainly composed of a polyvinyl alcohol resin containing iodine or a dichroic dye. This is because a liquid crystal display device having a high degree of polarization and a high contrast ratio in the front direction can be obtained. 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]. Alternatively, a commercially available polymer film can be used as it is. Commercially available polymer films include, for example, “Kuraray Vinylon Film” manufactured by Kuraray Co., Ltd., “Tocero Vinylon Film” manufactured by Tosero Co., Ltd., and “Nichigo” manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Vinylon film "and the like.

  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 a 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.

  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 of the polyvinyl alcohol resin is preferably 1200 to 3600, more preferably 1600 to 3200, and most preferably 1800 to 3000. The average degree of polymerization can be determined according to JIS K 6726-1994.

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

  As content (weight ratio) of the polyhydric alcohol in this invention, Preferably it is 1-30 with respect to the total solid content 100 of a polyvinyl alcohol-type resin, More preferably, it is 3-25, Most preferably ~ 20. By setting the content of the polyhydric alcohol within the above range, the dyeability and stretchability of the polarizer can be further improved.

  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. Examples of the surfactant include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. In the present invention, a nonionic surfactant is preferably used. 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.

  The content (weight ratio) of the surfactant is preferably more than 0 and 5 or less, more preferably more than 0 and 3 or less, most preferably more than 0 with respect to the polyvinyl alcohol resin 100. 1 or less. By setting the content of the surfactant in the above range, the dyeability and stretchability of the polarizer can be improved.

As the above dichromatic substance, any suitable dichromatic substance may be employed. Specific examples include iodine or a dichroic dye. In the present specification, the term "dichroic" refers to optical anisotropy in which light absorption differs in two directions of a direction perpendicular thereto the optical axis direction.

As the dichroic dye, for example, Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, sky blue LG, Remon'ero, blue BR, Blue 2R, Navy RY, Green LG, Violet LB, 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 350. Preferably, the moisture content is 5% to 40%, more preferably 10% to 30%, and most preferably 20% to 30%.

D. First Optical Element Referring to FIGS. 1 and 2, the first optical element 30 is disposed between the liquid crystal cell 10 and the first polarizer 21. According to such a configuration, the first optical element functions as a protective layer on the cell side of the polarizer, prevents the polarizer from being deteriorated, and as a result, improves the display characteristics of the liquid crystal display device for a long time. Can be maintained. The first optical element 30 satisfies the following expressions (1) and (2), and is arranged so that its slow axis is substantially parallel to the absorption axis of the first polarizer.
10 nm <Re [590] (1)
| Rth [590] -Re [590] | <10 nm (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  When the refractive index in the slow axis direction is nx, the refractive index in the fast axis direction is ny, and the refractive index in the thickness direction is nz, the first optical element satisfies nx> ny = nz. The slow axis is the direction in which the in-plane refractive index is maximized. Ideally, the first optical element has an optical axis in one direction in the plane. 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 the absolute value of the difference between the in-plane retardation value (Re [590]) and the thickness direction retardation value (Rth [590]). : | Rth [590] -Re [590] | is less than 10 nm.

D-1. Optical Characteristics of First Optical Element In this specification, Re [590] refers to an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C. Here, “in-plane retardation value” means an in-plane retardation value when the optical element is composed of a single retardation film, and the optical element includes a retardation film. Means an in-plane retardation value of the entire laminate. Re [590] is expressed by the formula: Re [590, where the refractive index in the slow axis direction and the fast axis direction of the optical element at a wavelength of 590 nm is nx and ny, respectively, and d (nm) is the thickness of the optical element. ] = (Nx−ny) × d. The slow axis means the direction in which the in-plane refractive index is maximum.

  Any appropriate value may be set as long as Re [590] of the first optical element exceeds 10 nm. Re [590] of the first optical element is preferably more than 10 nm and 1000 nm or less, more preferably more than 10 nm and 500 nm or less, particularly preferably 30 nm to 400 nm, and most preferably 60 nm to 300 nm. . By setting Re [590] of the first optical element in the above range, the variation in the angle (orientation angle) of the slow axis of the first optical element is reduced, and the amount of light leakage in the oblique direction is small and clear. A liquid crystal display device capable of displaying an image can be obtained.

  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] is expressed by the formula: Rth [590] = (nx) where the refractive index in the slow axis direction and thickness direction of the optical element at a wavelength of 590 nm is nx and nz, respectively, and d (nm) is the thickness of the optical element. −nz) × d. The slow axis refers to the direction in which the in-plane refractive index is maximum.

  Rth [590] of the first optical element can be set to any appropriate value as long as the above expressions (1) and (2) are satisfied. The Rth [590] of the first optical element is preferably more than 10 nm. The Rth [590] is more preferably more than 10 nm and 1000 nm or less, particularly preferably 30 nm to 400 nm, and most preferably 60 nm to 300 nm. By setting Rth [590] of the first optical element in the above range, the variation in the angle (orientation angle) of the slow axis of the first optical element is reduced, the amount of light leakage in the oblique direction is small, and a clear image is obtained. Can be obtained.

  In this specification, Rth [590] / Re [590] refers to a ratio between a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C. and an in-plane retardation value (also referred to as an Nz coefficient). . Rth [590] / Re [590] of the first optical element can be set to any appropriate value within a range that satisfies the above expressions (1) and (2). Rth [590] / Re [590] of the first optical element is preferably more than 0.1 and less than 2.0, more preferably 0.3 to 1.8, and particularly preferably 0.7. It is -1.3, Most preferably, it is 0.9-1.1. By setting Rth [590] / Re [590] in the above range, a liquid crystal display device having a small color shift amount in an oblique direction can be obtained.

Re [590], Re [480], and Rth [590] can be measured using a product name “KOBRA21-ADH” manufactured by Oji Scientific Instruments. In-plane retardation value (Re) at a wavelength of 590 nm at 23 ° C., retardation value measured by tilting 40 degrees with the slow axis as the tilt axis (R40), optical element thickness (d), and average refractive index of the optical element Using the rate (n0), nx, ny and nz can be obtained by computer numerical calculation from the following formulas (i) to (iv), 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)

D-2. Arrangement Means of First Optical Element Referring to FIG. 1, any appropriate method may be adopted as a method of arranging the first optical element 30 depending on the purpose. Preferably, the first optical element 30 is provided with an adhesive layer (not shown) on the surface thereof, and is attached to the first polarizer 21 and the liquid crystal cell 10. 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. Furthermore, since the adverse effects of reflection and refraction generated at the interface between the layers of each optical element can be reduced, a liquid crystal display device capable of displaying a clear image can be obtained.

  The first optical element 30 is arranged so that its slow axis is substantially parallel to the absorption axis of the first polarizer 21. According to such a form, roll production is possible and bonding becomes easy, As a result, manufacturing efficiency can improve significantly. In this specification, “substantially parallel” means that the angle formed by the slow axis of the first optical element 30 and the absorption axis of the first polarizer 21 is 0 ° ± 2.0 °. And preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °.

  The thickness of the adhesive layer can be determined as appropriate according to the purpose of use and adhesive strength. Preferably, the thickness of the adhesive layer is 0.1 μm to 100 μm, more preferably 0.5 μm to 50 μm. By setting the thickness of the adhesive layer in the above range, the optical element and the polarizer to be joined do not float or peel off, and an adhesive force and an adhesive time that do not have a practically adverse effect can be obtained.

  As a material for forming the adhesive layer, an appropriate material can be appropriately selected from those exemplified in the section C-2. Preferably, it is a pressure-sensitive adhesive having an acrylic polymer as a base polymer in terms of excellent optical transparency, moderate wettability, cohesiveness, and adhesive properties, and excellent weather resistance and heat resistance. (Also referred to as an acrylic pressure-sensitive adhesive) is used. A commercially available double-sided optical tape can be used as it is for the adhesive layer. As a commercially available optical double-sided tape, for example, trade name “SK-2057” manufactured by Soken Chemical Co., Ltd. may be mentioned.

D-3. Configuration of First Optical Element The configuration (laminated structure) of the first optical element used in the present invention is not particularly limited as long as it satisfies the optical characteristics described in the above section D-1. Specifically, the first optical element may be a retardation film alone or a laminate composed of two or more retardation films. Preferably, the first optical element 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 first optical element is a laminate, an adhesive layer 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] and Rth [590] of the retardation film used in the first optical element can be appropriately selected depending on the number of retardation films used. For example, when the first optical element is composed of a single retardation film, Re [590] and Rth [590] of the retardation film are equal to Re [590] and Rth [590] of the first optical element. Each is preferably equal. Therefore, for example, the retardation value of the adhesive layer used when the first optical element is laminated on the polarizer is preferably as small as possible. For example, when the first optical element is a laminate including two or more retardation films, the sum of Re [590] and Rth [590] of the respective retardation films is equal to that of the first optical element. It is preferable to design such that Re [590] and Rth [590] are equal.

  Specifically, the first optical element having Re [590] of 140 nm and Rth [590] of 140 nm is obtained by using a retardation film having Re [590] of 70 nm and Rth [590] of 70 nm. Two layers can be obtained by laminating so that each slow axis is parallel to each other. Alternatively, a retardation film in which Re [590] is 50 nm and Rth [590] is 60 nm, and a retardation film in which Re [590] is 90 nm and Rth [590] is 80 nm are respectively retarded. Two sheets can be obtained by laminating so that the axes are parallel to each other. 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 first optical element varies depending on the configuration, but is preferably 50 μm to 200 μm, more preferably 55 μm to 200 μm, particularly preferably 60 μm to 180 μm, and most preferably 70 μm to 150 μm. . By setting the total thickness of the first optical element within the above range, an optical element excellent in mechanical strength and optical uniformity can be obtained.

D-4. Retardation film used for the first optical element Any appropriate film can be used as the retardation film used for the first optical element. The retardation film is preferably excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like.

  The thickness of the retardation film can vary depending on the number of laminated films. Typically, the total thickness of the obtained first optical element is preferably set to be 50 μm to 200 μm. For example, when the first optical element is composed of a single retardation film, the thickness of the retardation film is preferably 50 μm to 200 μm (that is, equal to the entire thickness of the first optical element). Also, for example, when the first optical element is a laminate of two retardation films, the thickness of each retardation film is arbitrary as long as the sum is a preferable overall thickness of the first optical element. A suitable thickness can be employed. Therefore, the thickness of each retardation film may be the same or different. In one embodiment in the case of laminating two retardation films, the thickness of one retardation film is preferably 25 μm to 100 μm.

The absolute value (C [590] (m ² / N)) of the photoelastic coefficient of the retardation film is preferably 1 × 10 ^{−12 to} 100 × 10 ⁻¹² , and more preferably 1 × 10 ⁻¹² to 60 × 10 ⁻¹² , particularly preferably 1 × 10 ⁻¹² to 30 × 10 ⁻¹² , and particularly preferably 1 × 10 ⁻¹² to 8 × 10 ⁻¹² . By using a material having an absolute value of the photoelastic coefficient in the above range as a material for the retardation film, a liquid crystal display device excellent in display uniformity 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 particularly preferably 90% or more. The first optical element preferably has the same light transmittance. The theoretical upper limit of the transmittance is 100%, and the realizable upper limit is 96%.

  The variation in the angle of the slow axis (also referred to as the orientation angle) of the retardation film is such that the range of the orientation angle variation at the five measurement points provided at equal intervals in the film width direction is ± 2 ° to ± 1 °. Some are preferably used. More preferably, it is ± 1 ° to ± 0.5 °. By setting the orientation angle in the above range, a liquid crystal display device having excellent display uniformity and capable of displaying a clear image can be obtained. The orientation angle can be appropriately adjusted depending on the stretching means, stretching method, stretching temperature, and stretching ratio described later.

  The first optical element used in the present invention preferably includes a retardation film containing a thermoplastic resin. This retardation film is a stretched film of a polymer film containing a thermoplastic resin. More preferably, the first optical element includes a retardation film containing a thermoplastic resin exhibiting positive intrinsic birefringence. If a polymer film containing a thermoplastic resin exhibiting positive intrinsic birefringence is used, the optical characteristics described in the above section D-1 can be obtained with good productivity by stretching in one direction. In the present specification, the “thermoplastic resin exhibiting positive intrinsic birefringence” means that the direction in which the refractive index increases in the film plane (slow axis direction) when the polymer film is stretched in one direction. , Which is substantially parallel to the stretching direction.

  General-purpose plastics such as polyolefin resins, cycloolefin resins, polyvinyl chloride resins, cellulose resins, polyvinyl acetate, polyvinylidene chloride resins; polyamide resins General-purpose engineering plastics such as polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin; polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyether ether ketone Super engineering plastics such as resin, polyarylate resin, liquid crystalline resin, polyamideimide resin, polyimide resin, polytetrafluoroethylene resin, etc. It is. The thermoplastic resins exhibiting positive intrinsic birefringence can be used alone or in combination of two or more. Alternatively, the thermoplastic resin exhibiting positive intrinsic birefringence can be used after any appropriate polymer modification. Examples of the polymer modification include modifications such as copolymerization, crosslinking, molecular terminals, and stereoregularity.

  Particularly preferably, the first optical element used in the present invention includes a retardation film containing a norbornene resin and / or a retardation film containing a cellulose resin. Since the retardation film containing the norbornene resin and the retardation film containing the cellulose resin have a small absolute value of the photoelastic coefficient, a liquid crystal display device excellent in display uniformity can be obtained. Most preferably, the first optical element is a single retardation film containing a norbornene resin. Alternatively, it is a laminate of a retardation film containing a norbornene resin and a retardation film containing a cellulose resin.

  In the present specification, the norbornene-based resin refers to a polymer obtained by using a norbornene-based monomer having a norbornene ring as a part or all of a starting material (monomer). The norbornene-based resin uses a norbornene-based monomer having a norbornene ring (having a double bond in the norbornane ring) as a starting material. In the (co) polymer state, the norbornene-based resin has a norbornane ring as a constituent unit. You may or may not have. A norbornene-based resin having no norbornane ring as a structural unit in the (co) polymer state is, for example, a (co) polymer obtained using a monomer that becomes a 5-membered ring by cleavage. Examples of the monomer that becomes a 5-membered ring by cleavage include norbornene, dicyclopentadiene, 5-phenylnorbornene, and derivatives thereof. When the norbornene-based resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be.

  As said norbornene-type resin, a commercially available thing can be used as it is. Or what carried out arbitrary appropriate polymer modification | denaturation to commercially available norbornene-type resin can be used. Examples of commercially available norbornene resins include Arton series (trade name: ARTON FLZR50, ARTON FLZR70, ARTON FLZL100, ARTON F5023, ARTON FX4726, ARTON FX4727, ARTON D4531, ARTON D4532, etc.) manufactured by JSR Corporation. ZEONOR series (trade names; ZEONOR 750R, ZEONOR 1020R, ZEONOR 1600, etc.), Mitsui Chemicals, Inc. Apel series (APL8008T, APL6509T, APL6011T, APL6013T, APL6015T, APL5014T, etc.), manufactured by TICONA Name; TOPAS) and the like.

  Examples of the norbornene resin include (A) a resin obtained by hydrogenating a ring-opening (co) polymer of a norbornene monomer, and (B) a resin obtained by addition (co) polymerization of a norbornene monomer. The ring-opening copolymer of the norbornene-based monomer is a resin obtained by hydrogenating a ring-opening copolymer of one or more norbornene-based monomers and α-olefins, cycloalkenes, and / or non-conjugated dienes. Include. The resin obtained by addition copolymerization of the norbornene monomer includes a resin obtained by addition copolymerization of one or more norbornene monomers with α-olefins, cycloalkenes and / or non-conjugated dienes. The norbornene-based resin is preferably a resin obtained by hydrogenating a ring-opening (co) polymer of (A) norbornene-based monomer. This is because it is possible to obtain a retardation film that is excellent in molding processability and has a large retardation value at a lower draw ratio.

  A resin obtained by hydrogenating the ring-opening (co) polymer of the norbornene monomer is subjected to a metathesis reaction of the norbornene monomer or the like to obtain a ring-opening (co) polymer. It can be obtained by hydrogenation. Specifically, for example, NTS Co., Ltd. “Development and application technology of optical polymer materials” p. 103-p. 111 (2003 edition), the method described in paragraphs [0059] to [0060] of JP-A-11-116780, and the paragraphs [0035] to [0037] of JP-A-2001-350017. And the method described in paragraph [0053] of JP-A-2005-008698. The resin obtained by addition (co) polymerization of the norbornene monomer can be obtained, for example, by the method described in Example 1 of JP-A No. 61-292601.

  The norbornene-based resin has a weight average molecular weight (Mw) as measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably 20,000 to 400,000, more preferably 25,000 to 200,000, particularly preferably in the range of 30,000 to 100,000, most 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.

  Arbitrary appropriate cellulose resins can be employ | adopted for the said cellulose resin. The cellulose-based resin is preferably a cellulose organic acid ester or a cellulose mixed organic acid ester in which part or all of the hydroxyl groups of cellulose are substituted with an acetyl group, a propionyl group and / or a butyl group. Examples of the cellulose organic acid ester include cellulose acetate, cellulose propionate, and cellulose butyrate. Examples of the cellulose mixed organic acid ester include cellulose acetate propionate and cellulose acetate butyrate. The cellulose resin can be obtained, for example, by the method described in JP-A-2001-188128 [0040] to [0041].

  A commercially available cellulose resin can be used as it is. Or what carried out arbitrary appropriate polymer modification | denaturation to commercially available resin can be used. Examples of the polymer modification include modifications such as copolymerization, crosslinking, molecular terminals, and stereoregularity. Examples of commercially available cellulose resins include cellulose acetate propionate resin (trade name: 307E-09, 360A-09, 360E-16) manufactured by Daicel Fine Chemical Co., Ltd., cellulose acetate (trade name; CA-) manufactured by EASTMAN. 398-30, CA-398-30L, CA-320S, CA-394-60S, CA-398-10, CA-398-3, CA-398-30, CA-398-6), cellulose buty manufactured by EASTMAN Rate (trade name; CAB-381-0.1, CAB-381-20, CAB-500-5, CAB-531-1, CAB-551-0.2, CAB-553-0.4), EASTMAN Cellulose acetate propionate (trade name; CAP-482-0.5, CAP-482) 20, CAP-504-0.2) and the like.

  The weight average molecular weight (Mw) of the cellulose resin is a value measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably from 20,000 to 1,000,000, more preferably from 25,000. 800,000, particularly preferably in the range of 30,000 to 400,000, most preferably in the range of 40,000 to 200,000. When the weight average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

  As a method for obtaining the polymer film containing the thermoplastic resin, any appropriate forming method can be used. Examples of the molding process include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, and solvent casting. Preferably, the molding method is a solvent casting method. This is because a film excellent in smoothness and optical uniformity can be obtained. Specifically, the solvent casting method includes, for example, defoaming a concentrated solution (dope) in which a resin composition containing a thermoplastic resin as a main component, an additive, and the like is dissolved in a solvent, and an endless stainless belt or a rotating drum. The film is cast uniformly on the surface of the film to form a film by evaporating the solvent.

  The conditions adopted at the time of molding of the polymer film containing the thermoplastic resin 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 for the type of solvent and the drying temperature, a film excellent in smoothness and optical uniformity can be obtained. The Re [590] and Rth [590] of the polymer film containing the thermoplastic resin can be appropriately adjusted depending on the resin composition and type, drying conditions, the thickness of the film after molding, and the like.

  The polymer film containing the thermoplastic resin 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 content (weight ratio) of the additive is preferably more than 0 and 20 or less, more preferably more than 0 and 10 or less, and most preferably more than 0 and 5 with respect to the thermoplastic resin 100. It is as follows.

  As the polymer film containing the thermoplastic resin, a commercially available film can be used as it is. Alternatively, a commercially available film subjected to secondary processing such as stretching treatment and / or relaxation treatment can be used. As a polymer film containing a commercially available norbornene resin, for example, Arton series (trade name; ARTON F, ARTON FX, ARTON D) manufactured by JSR Corporation, or Zeonore series (trade name: ZEONOR Corporation) manufactured by Optes Co., Ltd. ZF14, ZEONOR ZF16) and the like. As a polymer film containing a commercially available cellulose resin, for example, Fuji Photo Film Co., Ltd. Fujitac series (trade name: ZRF80S, TD80UF, TDY-80UL), Konica Minolta Opto Co., Ltd. trade name “KC8UX2M” Or the like.

  The retardation film used for the first optical element can be obtained, for example, by stretching a polymer film containing a thermoplastic resin. As the stretching method, for example, a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, or the like is used. 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 said extending | stretching, temperature may be changed continuously and may be changed in steps. 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). Further, for example, the film may be stretched in an oblique direction (obliquely stretched) using the stretching method described in FIG. 1 of JP-A-2003-262721. Re [590] and Rth [590] of the retardation film are appropriately adjusted depending on the retardation value before stretching, the film thickness, the stretching ratio, the stretching temperature, and the like.

  The stretching temperature (temperature in the stretching oven) for stretching the polymer film containing the thermoplastic resin is appropriately selected according to the target retardation value, the type and thickness of the polymer film to be used, and the like. The The stretching temperature is preferably Tg + 1 ° C. to Tg + 30 ° C. with respect to the glass transition temperature (Tg) of the polymer film. This is because the retardation value of the retardation film is likely to be uniform in the width direction, and the film is difficult to crystallize (white turbidity). Specifically, the stretching temperature is preferably 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 stretching temperature constant is not particularly limited, but it is heated for air conditioning, an air circulation type thermostatic oven in which hot air or cold air circulates, a microwave or far infrared ray, or the like. Appropriate ones are appropriately selected from heating methods such as hot rolls, heat pipe rolls or metal belts and temperature control methods.

  The draw ratio at the time of drawing the polymer film containing the thermoplastic resin can be appropriately selected according to the target retardation value, the type and thickness of the polymer film to be used, and the like. The draw ratio is usually more than 1 time and 3 times or less, preferably more than 1 time and 2 times or less, more preferably more than 1 time and 1.5 times or less with respect to the original length. 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. If it is said extending | stretching conditions, not only the optical characteristic of the said D-1 term can be satisfied, but the retardation film excellent in optical uniformity can be obtained.

E. Second Optical Element In the liquid crystal panel of the present invention, an arbitrary optical element can be disposed between the liquid crystal cell and the second polarizer. FIG. 4 is a schematic cross-sectional view of a liquid crystal panel according to another embodiment of the present invention. FIG. 5A is a schematic perspective view when the liquid crystal panel adopts the E mode, and FIG. 5B is a schematic perspective view when the liquid crystal panel adopts the O mode. It should be noted that the ratio of the length, width, and thickness of each component in FIG. 4 and FIGS. 5 (a) and 5 (b) is different from the actual one. The liquid crystal panel 101 further includes a second optical element between the liquid crystal cell 10 and the second polarizer 22. According to such a configuration, the second optical element functions as a protective layer on the cell side of the polarizer, prevents the polarizer from being deteriorated, and as a result, improves the display characteristics of the liquid crystal display device for a long time. Can be maintained. The second optical element 40 satisfies the following expressions (3) and (4), and its slow axis is substantially parallel or substantially orthogonal to the absorption axis of the second polarizer 22. Be placed. In the illustrated example, the case where the slow axis of the second optical element 40 is substantially orthogonal to the absorption axis of the second polarizer 22 is shown, but this may be substantially parallel.
50 nm ≦ Rth [590] ≦ 200 nm (3)
−200 nm ≦ Rth [590] −Re [590] ≦ 80 nm (4)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  In the present invention, the second optical element is used to reduce light leakage in the oblique direction of the liquid crystal panel. In general, a liquid crystal panel in which two polarizers are arranged on both sides of a liquid crystal cell so that their absorption axes are orthogonal to each other causes light leakage in an oblique direction, and the absorption axes of each polarizer are 0 ° and 90 °. In this case, the amount of light leakage tends to become maximum at an oblique 45 ° azimuth. By reducing the light leakage amount, a liquid crystal display device that can display a clear image with a small light leakage amount in an oblique direction can be obtained.

Preferably, in the liquid crystal panel, an absolute value (Δd = | d ₁ −d ₂ |) of a difference between the thickness (d ₁ ) of the first optical element and the thickness (d ₂ ) of the second optical element is 100 μm or less. It is. Δd is more preferably 80 μm or less, particularly preferably 50 μm or less, and most preferably 30 μm or less. By setting the Δd in the above range, a liquid crystal display device excellent in display uniformity can be obtained by preventing the liquid crystal panel from being warped due to the heat of the backlight.

E-1. Optical Properties of Second Optical Element Rth [590] of the second optical element is preferably 50 nm to 200 nm, more preferably 50 nm to 180 nm, particularly preferably 70 nm to 160 nm, and most preferably 100 nm to 140 nm. By setting Rth [590] in the above range, a liquid crystal display device capable of displaying a clear image with a small amount of light leakage in an oblique direction can be obtained.

  The difference between Rth [590] and Re [590] of the second optical element (Rth [590] −Re [590]) is preferably −200 nm to 80 nm, more preferably −180 nm to 60 nm, Particularly preferred is -160 nm to -40 nm, and most preferred is -140 nm to -100 nm. By setting (Rth [590] −Re [590]) in the above range, a liquid crystal display device capable of displaying a clear image with a small amount of light leakage in an oblique direction can be obtained.

  As Re [590] of the second optical element used in the present invention, an appropriate value can be appropriately selected within the range satisfying the above-described formula (4). The Re [590] is preferably 0 nm to 400 nm, more preferably 0 nm to 360 nm, particularly preferably 110 nm to 320 nm, and most preferably 200 nm to 280 nm. By setting Re [590] of the second optical element in the above range, a liquid crystal display device that can display a clear image with a small amount of light leakage in an oblique direction can be obtained.

  In this specification, Rth [590] / Re [590] refers to the ratio (also referred to as Nz coefficient) of the thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C. to the in-plane retardation value. The Nz coefficient of the second optical element is preferably more than 0 and less than 1. The Nz coefficient is more preferably 0.3 to 0.7, and particularly preferably 0.4 to 0.6. By setting the Nz coefficient in the above range, a liquid crystal display device in which the angle dependency of the retardation value is appropriately adjusted and the amount of light leakage in the oblique direction is further reduced can be obtained.

E-2. Arrangement Means of Second Optical Element Referring to FIG. 4, any appropriate method can be adopted as a method of arranging the second optical element 40 depending on the purpose. Preferably, the second optical element 40 is provided with an adhesive layer (not shown) on the surface thereof and is attached to the second polarizer 22 and the liquid crystal cell 10. 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. Furthermore, since the adverse effects of reflection and refraction generated at the interface between the layers of each optical element can be reduced, a liquid crystal display device capable of displaying a clear image can be obtained.

  The second optical element 40 is preferably arranged so that its slow axis is substantially parallel or orthogonal to the absorption of the second polarizer 22. In this specification, “substantially parallel” includes an angle formed by the slow axis of the second optical element 40 and the absorption axis of the second polarizer 22 is 0 ° ± 2.0 °, The angle is preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °. “Substantially orthogonal” includes an angle formed by the slow axis of the second optical element 40 and the absorption axis of the second polarizer 22 is 90 ° ± 2.0 °, preferably 90 ° ± The angle is 1.0 °, more preferably 90 ° ± 0.5 °.

  The thickness of the adhesive layer can be determined as appropriate according to the purpose of use and adhesive strength. Preferably, the thickness of the adhesive layer is 0.1 μm to 100 μm, more preferably 0.5 μm to 50 μm. By setting the thickness of the adhesive layer in the above range, the optical element and the polarizer to be joined do not float or peel off, and an adhesive force and an adhesive time that do not have a practically adverse effect can be obtained.

  As a material for forming the adhesive layer, an appropriate material can be appropriately selected from those exemplified in the section C-2. Preferably, it is a pressure-sensitive adhesive having an acrylic polymer as a base polymer in terms of excellent optical transparency, moderate wettability, cohesiveness, and adhesive properties, and excellent weather resistance and heat resistance. (Also referred to as an acrylic pressure-sensitive adhesive) is used. A commercially available double-sided optical tape can be used as it is for the adhesive layer. As a commercially available optical double-sided tape, for example, trade name “SK-2057” manufactured by Soken Chemical Co., Ltd. may be mentioned.

E-3. Configuration of Second Optical Element The configuration (laminate structure) of the second optical element used in the present invention is not particularly limited as long as it satisfies the optical characteristics described in the above section E-1. Specifically, the second optical element may be a retardation film alone or a laminate composed of two or more retardation films. Preferably, the second optical element is a single retardation film or a laminate of two retardation films. This is because the amount of light leakage in the oblique direction and the amount of color shift can be reduced. When the second optical element is a laminate, an adhesive 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 Section E-4.

  Re [590] and Rth [590] of the retardation film used in the second optical element can be appropriately selected depending on the number of retardation films used. For example, when the second optical element is composed of a single retardation film, Re [590] and Rth [590] of the retardation film are equal to Re [590] and Rth [590] of the second optical element. Each is preferably equal. Therefore, for example, the retardation value of the adhesive layer used when the second optical element is laminated on the polarizer is preferably as small as possible. For example, when the second optical element is a laminate including two or more retardation films, the sum of Re [590] and Rth [590] of the respective retardation films is equal to that of the second optical element. It is preferable to design such that Re [590] and Rth [590] are equal.

  Specifically, the second optical element having Re [590] of 200 nm and Rth [590] of 80 nm is a retardation film having Re [590] of 100 nm and Rth [590] of 40 nm. Two layers can be obtained by laminating so that each slow axis is parallel to each other. 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.

  An appropriate value can be appropriately selected as the overall thickness of the second optical element according to the overall thickness of the first optical element. Preferably, it is set equal to the entire thickness of the first optical element. Specifically, the total thickness of the second optical element is preferably 50 μm to 200 μm, more preferably 55 μm to 200 μm, particularly preferably 60 μm to 180 μm, and most preferably 70 μm to 150 μm. By setting the total thickness of the second optical element in the above range, an optical element having excellent mechanical strength and optical uniformity can be obtained.

E-4. Retardation film used for 2nd optical element Arbitrary appropriate retardation films can be employ | adopted as a retardation film used for a 2nd optical element. The retardation film is preferably excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like.

  The thickness of the retardation film can vary depending on the number of laminated films. Typically, the overall thickness of the obtained second optical element is preferably set to be 50 μm to 200 μm. For example, when the second optical element is composed of a single retardation film, the thickness of the retardation film is preferably 50 μm to 200 μm (that is, equal to the entire thickness of the second optical element). Further, for example, when the second optical element is a laminate of two retardation films, the thickness of each retardation film is arbitrary as long as the total is a preferable overall thickness of the second optical element. A suitable thickness can be employed. Therefore, the thickness of each retardation film may be the same or different. In one embodiment in the case of laminating two retardation films, the thickness of one retardation film is preferably 25 μm to 100 μm.

The absolute value (C [590] (m ² / N)) of the photoelastic coefficient of the retardation film is preferably 1 × 10 ^{−12 to} 100 × 10 ⁻¹² , and more preferably 1 × 10 ⁻¹² to 60 × 10 ⁻¹² , particularly preferably 1 × 10 ⁻¹² to 30 × 10 ⁻¹² , and particularly preferably 1 × 10 ⁻¹² to 8 × 10 ⁻¹² . By using a material having an absolute value of the photoelastic coefficient in the above range as a material for the retardation film, a liquid crystal display device excellent in display uniformity 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 particularly preferably 90% or more. The first optical element preferably has the same light transmittance. The theoretical upper limit of the transmittance is 100%, and the realizable upper limit is 96%.

  The variation in the angle of the slow axis (also referred to as the orientation angle) of the retardation film is such that the range of the orientation angle variation at the five measurement points provided at equal intervals in the film width direction is ± 2 ° to ± 1 °. Some are preferably used. More preferably, it is ± 1 ° to ± 0.5 °. By setting the orientation angle in the above range, a liquid crystal display device having excellent display uniformity and capable of displaying a clear image can be obtained. The orientation angle can be appropriately adjusted depending on the stretching means, stretching method, stretching temperature, and stretching ratio described later.

  The second optical element used in the present invention preferably includes a retardation film containing a thermoplastic resin. This retardation film is a stretched film of a polymer film containing a thermoplastic resin. More preferably, the second optical element includes a retardation film containing a thermoplastic resin exhibiting positive intrinsic birefringence. If a polymer film containing a thermoplastic resin exhibiting positive intrinsic birefringence is used, the optical characteristics described in the above section E-1 can be obtained with high productivity by, for example, a stretching method using a shrinkable film described later. Because it can. As the thermoplastic resin exhibiting positive intrinsic birefringence, those described in the above section D-4 can be used.

  Particularly preferably, the second optical element used in the present invention includes a retardation film containing a norbornene resin and / or a retardation film containing a cellulose resin. Since the retardation film containing the norbornene resin and the retardation film containing the cellulose resin have a small absolute value of the photoelastic coefficient, a liquid crystal display device excellent in display uniformity can be obtained. Most preferably, the second optical element is a single retardation film containing a norbornene resin. Alternatively, it is a laminate of a retardation film containing a norbornene resin and a retardation film containing a cellulose resin. As said norbornene-type resin and said cellulose-type resin, a suitable thing can be selected suitably from what was described in said D-4 section.

  The retardation film used for the second optical element is obtained by, for example, pasting a shrinkable film on both sides of a polymer film containing a thermoplastic resin and heating and stretching the film by a longitudinal uniaxial stretching method using a roll stretching machine. be able to. The shrinkable film is used for imparting a shrinkage force in a direction perpendicular to the stretching direction at the time of heat stretching and increasing a refractive index (nz) in the thickness direction. A method for attaching the shrinkable film to both surfaces of the polymer film is not particularly limited, but an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer between the polymer film and the shrinkable film. A method of providing a layer and bonding is preferable from the viewpoint of excellent workability and economical efficiency.

  An example of the method for producing the retardation film will be described with reference to FIG. FIG. 6 is a schematic diagram showing a concept of a typical manufacturing process of a retardation film used for the second optical element. For example, the polymer film 402 containing a thermoplastic resin is fed out from the first feeding unit 401, and fed out from the second feeding unit 403 on both surfaces of the polymer film 402 by the laminate rolls 407 and 408. The shrinkable film 404 including the pressure-sensitive adhesive layer and the shrinkable film 406 including the pressure-sensitive adhesive layer fed out from the third feeding portion 405 are bonded together. The polymer film having the shrinkable film attached on both sides is given a tension in the longitudinal direction of the film by rolls 410, 411, 412 and 413 having different speed ratios while being held at a constant temperature by the heating means 409 ( At the same time, the film is subjected to a stretching treatment while being given a tension in the thickness direction by the shrinkable film. The stretched film 418 is peeled off at the first winding portion 414 and the second winding portion 415 together with the shrinkable films 404 and 406 together with the adhesive layer, and wound at the third winding portion 419. It is done.

  The shrinkable film is preferably a stretched film such as a biaxially stretched film or a uniaxially stretched film. The shrinkable film can be obtained, for example, by stretching an unstretched film formed into a sheet by an extrusion method in the longitudinal and / or transverse direction at a predetermined magnification with a simultaneous biaxial stretching machine or the like. The molding and stretching conditions can be appropriately selected depending on the composition, type and purpose of the resin used.

  Examples of the material used for the shrinkable film include polyester, polystyrene, polyethylene, polypropylene, polyvinyl chloride, and polyvinylidene chloride. From the viewpoint of excellent shrinkage uniformity and heat resistance, a biaxially stretched polypropylene film is preferably used.

In one embodiment, the shrinkage ratio in the film longitudinal direction at 140 ° C. of the shrinkable film: S ¹⁴⁰ [MD] is preferably 4% to 7%, and S ¹⁴⁰ [TD] is 11% to 16%. In another embodiment, the shrinkage ratio in the longitudinal direction of the shrinkable film at 160 ° C .: S ¹⁶⁰ [MD] is preferably 17% to 21%, and S ¹⁶⁰ [TD] is 40% to 52%. . By setting the shrinkage rate at each temperature of the shrinkable film within the above range, a retardation film having a target retardation value and excellent in uniformity can be obtained.

In one embodiment, the difference between the shrinkage ratio in the width direction and the shrinkage ratio in the longitudinal direction at 140 ° C. of the shrinkable film: ΔS ¹⁴⁰ = S ¹⁴⁰ [TD] −S ¹⁴⁰ [MD] is preferably 4% to 8%. In another embodiment, the difference between the shrinkage in the width direction and the shrinkage in the longitudinal direction at 160 ° C. of the shrinkable film: ΔS ¹⁶⁰ = S ¹⁶⁰ [TD] −S ¹⁶⁰ [MD] is preferably 20% to 30%. If the shrinkage rate in the MD direction is large, in addition to stretching tension, the shrinking force of the shrinkable film may be applied to a stretching machine, making uniform stretching difficult. By setting the shrinkage rate of the shrinkable film in the above range, uniform stretching can be performed without applying an excessive load to equipment such as a stretching machine.

The shrinkage stress in the width direction at 140 ° C. of the shrinkable film: T _A ¹⁴⁰ [TD] is preferably 0.5 N / 2 mm to 0.9 N / 2 mm. Furthermore, shrinkage stress per unit area at 140 ° C. of the shrinkable film: T _B ¹⁴⁰ [TD] is preferably ^{4.0N / mm 2 ~8.0N / mm 2} . By setting the shrinkage rate of the shrinkable film in the above range, a retardation film having a target retardation value and excellent in uniformity can be obtained.

The shrinkage stress in the width direction at 150 ° C. of the shrinkable film: T _A ¹⁵⁰ [TD] is preferably 0.6 N / 2 mm to 1.0 N / 2 mm. The shrinkage stress per unit area at 150 ° C. of the shrinkable film: T _B ¹⁵⁰ [TD] is preferably 5.0 N / mm ^{2 to} 9.0 N / mm ² . By setting the shrinkage rate of the shrinkable film in the above range, a retardation film having a target retardation value and excellent in uniformity can be obtained.

  If it is a shrinkable film having the above characteristics, it is possible to increase the refractive index in the thickness direction of a polymer film containing a norbornene-based resin, which has been difficult in the past, and as a result, the desired retardation value is obtained. Can be obtained. In the present invention, when the second optical element includes a retardation film containing a norbornene-based resin, since the absolute value of the photoelastic coefficient of the stretched film is small, the contraction stress of the polarizer and the heat of the backlight As a result, the display characteristics of the liquid crystal display device can be maintained high for a long time.

  The shrinkage rates S [MD] and S [TD] can be determined according to the method of heating shrinkage rate A of JIS Z 1712-1997 (however, the heating temperature is 140 ° C (or 160 ° C) instead of 120 ° C). And a load of 3 g was added to the test piece). Specifically, five test pieces each having a width of 20 mm and a length of 150 mm were taken from the vertical [MD] and horizontal [TD] directions, and a test piece with a mark at a distance of about 100 mm was prepared at the center of each. To do. The test piece was suspended vertically in an air circulation drying oven maintained at a temperature of 140 ° C. ± 3 ° C. (or 160 ° C. ± 3 ° C.) with a load of 3 g, heated for 15 minutes, taken out, and standard. After standing in the state (room temperature) for 30 minutes, the distance between the gauge points was measured using a caliper specified in JIS B 7507, and the average value of the five measured values was obtained. S (%) = [[[ The distance between the gauge points before heating (mm) −the distance between gauge points after heating (mm)] / the distance between gauge points before heating (mm)] × 100.

In addition, the shrinkable film can be used for general packaging, food packaging, pallet packaging, shrinkage label, cap seal, and electrical insulation as long as the object of the present invention is satisfied. A commercially available shrinkable film can be appropriately selected and used. These commercially available shrinkable films may be used as they are, or after being subjected to secondary processing such as stretching treatment or shrinkage treatment. Examples of commercially available shrinkable films include, for example, Oji Paper Co., Ltd., Alfane Series (trade name; Alphan P, Alphan S, Alphan H, etc.), Gunze Co., Ltd., Fancy Top Series (trade name; Fancy) Top EP1, Fancy Top EP2, etc.), Toray Industries, Inc. Trefan BO series (trade names; 2570, 2873, 2500, 2554, M114, M304, etc.), Sun Tox Corporation Sun Tox-OP series (PA20, PA21, PA30 etc.), Tosero Co., Ltd. Tosero OP series (trade names; OPU-0, OPU-1, OPU-2 etc.) and the like.

  The temperature in the stretching oven (also referred to as the stretching temperature) when heating and stretching the laminate of the polymer film containing the thermoplastic resin and the shrinkable film is the target retardation value, the type of polymer film used, It can be appropriately selected depending on the thickness and the like. The stretching temperature is preferably Tg + 1 ° C. to Tg + 30 ° C. with respect to the glass transition temperature (Tg) of the polymer film. This is because the retardation value tends to be uniform, and the film is difficult to crystallize (white turbidity). Specifically, the stretching temperature is preferably 110 ° C to 185 ° C, more preferably 120 ° C to 170 ° C. The glass transition temperature (Tg) can be determined by a DSC method according to JIS K 7121-1987.

  Furthermore, the stretching ratio (stretching ratio) when stretching a laminate of a polymer film containing a thermoplastic resin and a shrinkable film depends on the target retardation value, the type and thickness of the polymer film used, etc. It can be selected as appropriate. The draw ratio is usually more than 1 and 3 times or less, preferably 1.1 to 2 times, more preferably 1.2 to 1.8 times the original length. The feed speed at the time of stretching is not particularly limited, but is preferably 1 m / min to 20 m / min from the mechanical accuracy and stability of the stretching apparatus. If it is said extending | stretching conditions, not only the optical characteristic of the said E-1 term can be satisfied, but the retardation film excellent in the optical uniformity can be obtained.

F. Liquid Crystal Display Device FIG. 7 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It should be noted that, for the sake of easy understanding, the ratio of the vertical, horizontal, and thickness of each component shown in FIG. 7 is different from the actual ratio. The liquid crystal display device 200 includes a liquid crystal panel 100 (or a liquid crystal panel 101), protective layers 60 and 60 ′ disposed on both sides of the liquid crystal panel 100, and a surface treatment disposed further outside the protective layers 60 and 60 ′. Layers 70 and 70 ', and a backlight unit 80 disposed outside (backlight side) the surface treatment layer 70'. The backlight unit 80 includes a backlight 81, a reflection film 82, a diffusion plate 83, a prism sheet 84, and a brightness enhancement film 85. By using these optical members, it is possible to obtain a liquid crystal display device further excellent in display characteristics. In addition, as long as the effect of the present invention is obtained, a part of the optical member illustrated in FIG. 7 can be omitted depending on the application, such as an illumination method of a liquid crystal display device and a driving mode of a liquid crystal cell, or Other optical members can be substituted.

  Any appropriate film may be employed as the protective layer depending on the purpose. The protective layer is used for preventing the polarizer from contracting and expanding, and preventing deterioration due to ultraviolet rays. As the protective layer, for example, a polymer film containing a cellulose resin or a norbornene resin is used. The thickness of the polymer film is preferably 10 μm to 200 μm. In addition, the said protective layer may serve as the base film of the surface treatment layer mentioned later. As the protective layer, a commercially available polymer film can be used as it is. Alternatively, a commercially available polymer film can be used after being subjected to a surface treatment described later. Examples of the polymer film containing a commercially available cellulose resin include Fujitac series manufactured by Fuji Photo Film Co., Ltd., and trade name “KC8UX2M” manufactured by Konica Minolta Opto. Examples of the polymer film containing a commercially available norbornene-based resin include Arton series manufactured by JSR Corporation, Zeonore series manufactured by Optes Corporation.

  As the surface treatment layer, a treatment layer subjected to a hard coat treatment, an antistatic treatment, an antireflection treatment (also referred to as an antireflection treatment), a diffusion treatment (also referred to as an antiglare treatment), or the like is used. These surface treatment layers are used for the purpose of preventing the screen from being soiled or damaged, or preventing the display image from becoming difficult to see due to the reflection of indoor fluorescent light or sunlight on the screen. In general, the surface treatment layer is formed by fixing a treatment agent for forming the treatment layer on the surface of a base film. The base film may also serve as the protective layer. Further, the surface treatment layer may have a multilayer structure in which, for example, a hard coat treatment layer is laminated on an antistatic treatment layer. As the surface treatment layer, a commercially available surface treatment layer can be used as it is. Examples of the commercially available film subjected to the hard coat treatment and the antistatic treatment include “KC8UX-HA” manufactured by Konica Minolta Opto Co., Ltd. Examples of the commercially available surface treatment layer that has been subjected to the antireflection treatment include ReaLook series manufactured by NOF Corporation.

  Any appropriate illumination method can be adopted as the illumination method of the liquid crystal display device in which the liquid crystal panel of the present invention is used. Specific examples of the illumination method include a transmissive type in which a backlight is used as a light source and viewed by irradiating light from the back surface, a reflective type in which external light is applied to the screen, and a transflective type having both properties. It is done. The illumination method is preferably a transmission type. When the direct unit is adopted as the irradiation method, the backlight unit is generally composed of a backlight, a reflection film, a diffusion plate, a prism sheet, and a brightness enhancement film. When the edge light system is adopted, a light guide plate and a light reflector are further used in addition to the configuration of the direct system.

  Any appropriate backlight can be adopted as the backlight. Examples of the backlight include a cold cathode fluorescent tube (CCFL), a light emitting diode (LED), an organic EL (OLED), and a field emission device (FED). In the case where a cold cathode fluorescent tube is employed for the backlight, examples of the irradiation method include “directly underneath” that irradiates from directly below the liquid crystal and “edge light” that irradiates from the lateral end of the liquid crystal. The direct method has an advantage that high luminance can be obtained, and the edge light method can make the liquid crystal display device thinner than the direct method. Furthermore, there is an advantage that the influence of heat from the light source to each component can be reduced. When a light emitting diode is employed for the backlight, the color of the light source may be white or RGB three colors. When an RGB three-color light source is used for the light emitting diode, a field sequential type liquid crystal display device capable of color display without using a color filter can be obtained.

  The reflective film is used to prevent light from being lost to the side opposite to the viewing side of the liquid crystal panel and to make the light of the backlight enter the light guide plate efficiently. As the reflective film, for example, a polyethylene terephthalate film on which silver is vapor-deposited or a laminated film in which a polyester resin is laminated in multiple layers is used. The reflectance of the reflective film is preferably 90% or more over the entire wavelength range of 410 nm to 800 nm. The thickness of the reflective film is typically 50 μm to 200 μm. As the reflective film, a commercially available reflective film can be used as it is. As a commercially available reflective film, for example, Lemon White series manufactured by Kimoto Co., Ltd., Vicuity ESR series manufactured by Sumitomo 3M Co., Ltd. and the like can be mentioned.

  The light guide plate is used to spread light from the backlight over the entire screen. As the light guide plate, for example, an acrylic resin, a polycarbonate resin, a cycloolefin resin, or the like formed into a tapered shape so that the thickness decreases as the distance from the light source increases.

  The diffusion plate is used to guide light emitted from the light guide plate to a wide angle and make the screen uniform brightness. Furthermore, the diffuser plate can also reduce luminance unevenness of the backlight. As the diffusion plate, for example, a polymer film that has been subjected to uneven treatment or a polymer film containing a diffusion agent is used. The haze of the diffusion plate is preferably 85% to 92%. Furthermore, the total light transmittance of the diffusing plate is 90% or more. As the diffusion plate, a commercially available diffusion plate can be used as it is. Examples of the commercially available diffusion plate include OPLUS series manufactured by Eiwa Co., Ltd. and Light-up series manufactured by Kimoto Co., Ltd.

  The prism sheet is used to collect light having a wide angle by the light guide plate in a specific direction and improve the luminance in the front direction of the liquid crystal display device. As the prism sheet, for example, a sheet in which a prism layer made of an acrylic resin or a photosensitive resin is laminated on the surface of a base film made of a polyester resin is used. As the prism sheet, a commercially available prism sheet can be used as it is. As a commercially available prism sheet, for example, Mitsubishi Rayon Co., Ltd. Diamond Art Series can be mentioned.

  The said brightness improvement film is used in order to improve the brightness | luminance of the front of a liquid crystal display device, and a diagonal direction. A commercially available brightness enhancement film can be used as it is. Examples of commercially available brightness enhancement films include the NIPOCS PCF series manufactured by Nitto Denko Corporation, the Vicuity DBEF series manufactured by Sumitomo 3M Limited, and the like.

  In the liquid crystal display device provided with the liquid crystal panel of the present invention, the average value of Δu′v ′ in a polar angle of 60 ° and all directions (0 ° to 360 °) when displaying a black image is preferably 0.090. Or less, more preferably 0.085 or less, and particularly preferably 0.080 or less. Alternatively, the maximum value of Δu′v ′ at a polar angle of 60 ° and in all directions (0 ° to 360 °) when displaying a black image is preferably 0.160 or less, and more preferably 0.150 or less. And particularly preferably 0.140 or less. The theoretical lower limit of this Δu′v ′ is zero. As the Δu′v ′ value is decreased, a liquid crystal display device having a smaller color shift amount when a black image is displayed can be obtained.

  Furthermore, in the liquid crystal display device, the average value of Δu′v ′ at an azimuth angle of 45 ° and a polar angle (0 ° to 78 °) when displaying a black image is preferably 0.120 or less. Preferably it is 0.100 or less, Most preferably, it is 0.080 or less. Alternatively, the maximum value of Δu′v ′ at an azimuth angle of 45 ° and a polar angle (0 ° to 78 °) when displaying a black image is preferably 0.200 or less, and more preferably 0.180 or less. And particularly preferably 0.150 or less. The theoretical lower limit of this Δu′v ′ is zero. As the Δu′v ′ value is decreased, a liquid crystal display device having a smaller color shift amount when a black image is displayed can be obtained.

  Furthermore, in the liquid crystal display device, the average value of Y values in a polar angle of 60 ° and in all directions (0 ° to 360 °) when displaying a black image is preferably 1.30 or less, and more preferably It is 1.00 or less, and particularly preferably 0.70 or less. Alternatively, the maximum Y value in a polar angle of 60 ° and in all directions (0 ° to 360 °) when displaying a black image is preferably 3.00 or less, and more preferably 2.00 or less. Particularly preferably, it is 1.50 or less. The theoretical lower limit of this Y value is zero. As the Y value is decreased, a liquid crystal display device having a smaller light leakage amount (resulting in a higher contrast ratio) when a black image is displayed can be obtained.

  Further, in the liquid crystal display device, the average value of Y values at an azimuth angle of 45 ° and a polar angle (0 ° to 78 °) when displaying a black image is preferably 1.50 or less, and more preferably. 1.10 or less, particularly preferably 0.70 or less. Alternatively, the maximum Y value at an azimuth angle of 45 ° and a polar angle (0 ° to 78 °) when displaying a black image is preferably 2.50 or less, and more preferably 1.50 or less. Particularly preferably, it is 1.00 or less. The theoretical lower limit of this Y value is zero. As the Y value is decreased, a liquid crystal display device having a smaller light leakage amount (resulting in a higher contrast ratio) when a black image is displayed can be obtained.

G. Applications of the liquid crystal panel of the present invention The applications in which the liquid crystal panel and the liquid crystal display device of the present invention are used are not particularly limited. , Portable devices such as personal digital assistants (PDAs), portable game consoles, household electrical devices such as video cameras, LCD TVs, microwave ovens, back monitors, monitors for car navigation systems, in-vehicle devices such as car audio, commercial stores It can be used in various applications such as exhibition equipment such as information monitors, security equipment such as monitoring monitors, nursing care and medical 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 above 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 moisture content of polarizer:
Using a Karl Fascher moisture meter [Kyoto Electronics Industry Co., Ltd., product name “MKA-610”], a sample cut into a size of 10 mm × 30 mm was placed in a heating furnace at 150 ° C. ± 1 ° C., and nitrogen gas (200 ml / min. ) Was bubbled into the titration cell solution and measured.
(2) 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"].
(3) Molecular weight measurement method:
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
(4) 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”.
(5) Measuring method of average 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) 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.
(7) Measuring method of transmittance (T [590]):
It measured with the light of wavelength 590nm in 23 degreeC using the ultraviolet visible spectrophotometer [The product name "V-560" by JASCO Corporation].
(8) Measuring method of absolute value (C [590]) of photoelastic coefficient:
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.
(9) Measuring method of shrinkage rate of shrinkable film:
It was determined according to the heat shrinkage ratio A method of JIS Z 1712-1997 (however, the heating temperature was changed to 140 ° C. (or 160 ° C.) instead of 120 ° C., and a load of 3 g was added to the test piece). Specifically, five test pieces each having a width of 20 mm and a length of 150 mm were taken from the vertical [MD] and horizontal [TD] directions, and a test piece with a mark at a distance of about 100 mm was prepared at the center of each. To do. The test piece was suspended vertically in an air circulation drying oven maintained at a temperature of 140 ° C. ± 3 ° C. (or 160 ° C. ± 3 ° C.) with a load of 3 g, heated for 15 minutes, taken out, and standard. After standing in the state (room temperature) for 30 minutes, the distance between the gauge points was measured using a caliper specified in JIS B 7507, and the average value of the five measured values was obtained. S (%) = [[[ Distance between gauge points before heating (mm) −Distance between gauge points after heating (mm)] / Distance between gauge points before heating (mm)] × 100.
(10) Measuring method of shrinkage stress of shrinkable film:
Using the following apparatus, the shrinkage stress T ¹⁴⁰ [TD] and the shrinkage stress T ¹⁵⁰ [TD] in the width [TD] direction at 140 ° C. and 150 ° C. were measured by the TMA method.
・ Equipment: “TMA / SS 6100” manufactured by Seiko Instruments Inc.
Data processing: “EXSTAR6000” manufactured by Seiko Instruments Inc.
・ Measurement mode: Constant temperature rise measurement (10 ℃ / min)
・ Measurement atmosphere: In air (23 ℃)
・ Load: 20mN
Sample size: 15mm x 2mm (long side is width [TD] direction)
(11) Measuring method of color shift amount (Δu′v ′) of liquid crystal display device:
The measurement was performed after 30 minutes had elapsed since the backlight was turned on in a dark room at 23 ° C. using the following method and measurement apparatus. Specifically, a black image is displayed on the liquid crystal display device, and the product name “EZ Contrast 160D” manufactured by ELDIM Co. is used to display the display screen in all directions (0 ° to 360 °) and polar angles (0 ° to 78 °; front to The hue, u ′ value and v ′ value in the oblique direction) were measured. The color shift amount (Δu′v ′ value) in the oblique direction was calculated from the following formula: [(0.25−u ′) ² + (0.45−v ′) ² ] ^1/2 . The long side direction of the liquid crystal panel was set to an azimuth angle of 0 °, and the normal direction of the liquid crystal panel was set to a polar angle of 0 °.
(12) Measuring method of black luminance (Y value) of liquid crystal display device:
The measurement was performed after 30 minutes 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 is displayed on the liquid crystal display device, and the product name “EZ Contrast 160D” manufactured by ELDIM Co., Ltd., displays all directions (0 ° to 360 °) and polar angles (0 ° to 78 °; front to oblique directions)) The Y value of the XYZ display system was measured. The long side direction of the liquid crystal panel was set to an azimuth angle of 0 °, and the normal direction of the liquid crystal panel was set to a polar angle of 0 °.

Production of Polarizer [Reference Example 1]
Polymer film mainly composed of polyvinyl alcohol [trade name “9P75R (thickness: 75 μm, average degree of polymerization: 2,400, degree of saponification: 99.9 mol%)” manufactured by Kuraray Co., Ltd.]] at 30 ° C. ± 3 In a dyeing bath containing iodine and potassium iodide held at ° C., 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 circulation type thermostatic oven at 50 ° C. ± 1 ° C. for 30 minutes to obtain polarizers P1 and P2. The optical characteristics of the polarizers P1 and P2 are as shown in Table 1.

Production of first optical element [Reference Example 2]
A polymer film (Tg = 135 ° C., average refractive index = 1.49, Re [590] = 4) containing a cellulose acetate propionate having a thickness of 133 μm [trade name “CAP-482-0.5” manufactured by EASTMAN Co., Ltd.] .3 nm, Rth [590] = 135.9 nm) was stretched 1.5 times in an air circulation oven at 145 ° C. ± 1 ° C. while maintaining the film longitudinal direction with a simultaneous biaxial stretching machine. Phase difference film 1-A was produced. The properties of the obtained retardation film 1-A are shown in Table 2 below together with the film properties of Reference Example 3 described later.

[Reference Example 3]
Polymer film containing norbornene-based resin having a thickness of 100 μm [“ZEONOR ZF14” manufactured by Optes Co., Ltd. (Tg = 136 ° C., average refractive index = 1.53, Re [590] = 2.0 nm, Rth [590] = 8.0 nm)] is stretched 1.2 times in an air circulation oven at 135 ° C. ± 1 ° C. while maintaining the film longitudinal direction with a simultaneous biaxial stretching machine to produce retardation film 1-B. did. The properties of the obtained retardation film 1-B are as shown in Table 2.

Production of second optical element [Reference Example 4]
A polymer film containing a cellulose resin having a thickness of 80 μm [trade name “TDY-80UL” (average refractive index = 1.48) manufactured by Fuji Photo Film Co., Ltd.] was used as it was to obtain a retardation film 2-A. The properties of the obtained retardation film 2-A are shown in Table 3 below together with the film properties of Reference Example 5 described later.

[Reference Example 5]
Polymer film containing norbornene-based resin having a thickness of 100 μm [“ZEONOR ZF14” manufactured by Optes Co., Ltd. (Tg = 136 ° C., average refractive index = 1.53, Re [590] = 2.0 nm, Rth [590] = A biaxially stretched polypropylene film having a thickness of 60 μm [trade name “Trephan BO2873” manufactured by Toray Industries, Inc.] was bonded to both sides of the acrylic adhesive layer (thickness 15 μm). Thereafter, the film longitudinal direction is held with a roll stretching machine and stretched 1.38 times in an air circulation oven at 146 ° C. ± 1 ° C. After stretching, the biaxially stretched polypropylene film is stretched with the acrylic pressure-sensitive adhesive layer. And it peeled together and produced retardation film 2-B. Table 3 shows the characteristics of the retardation film 2-B. Table 4 shows the physical properties of the used biaxially stretched polypropylene film (shrinkable film).

Preparation of liquid crystal cell [Reference Example 6]
Take out the liquid crystal panel from the liquid crystal display device [LCD manufactured by Hitachi, Ltd., trade name “Wooo” (model number: W32-L7000, screen size: 698 mm × 392 mm)] including the liquid crystal cell of the IPS mode, and All of the optical film disposed on the surface was removed, and the glass surfaces (front and back) of the liquid crystal cell were washed. The liquid crystal cell thus prepared was designated as liquid crystal cell A.

Production of liquid crystal panel and liquid crystal display device [Example 1]
The retardation film 1-A obtained in Reference Example 2 is used as the first optical element on the surface on the viewing side of the liquid crystal cell A obtained in Reference Example 6 via an acrylic pressure-sensitive adhesive layer (thickness 23 μm). The slow axis was stuck so as to be substantially parallel to the long side of the liquid crystal cell A (0 ° ± 0.5 °). Subsequently, the polarizer P1 obtained in Reference Example 1 is used as the first polarizer via the adhesive layer (thickness 1 μm) on the surface of the retardation film 1-A. It was stuck so as to be substantially parallel to the long side of A (0 ° ± 0.5 °). At this time, the initial alignment direction of the liquid crystal cell A, the slow axis of the retardation film 1-A (first optical element), and the absorption axis of the polarizer P1 (first polarizer) are substantially the same. Parallel. Next, the retardation film 2-A obtained in Reference Example 4 is used as the second optical element through the acrylic pressure-sensitive adhesive layer (thickness: 23 μm) on the surface of the backlight side of the liquid crystal cell A. The slow axis was stuck so as to be substantially orthogonal (90 ° ± 0.5 °) to the long side of the liquid crystal cell A. Subsequently, the polarizer P2 obtained in Reference Example 1 is used as the second polarizer through the adhesive layer (thickness 1 μm) on the surface of the retardation film 2-A. It was stuck so as to be substantially orthogonal (90 ° ± 0.5 °) to the long side of A. At this time, the absorption axis of the polarizer P1 and the absorption axis of the polarizer P2 are substantially orthogonal. The retardation film 2-A obtained in Reference Example 4 is used as a protective layer on the outside of the polarizers P1 and P2 (on the side opposite to the liquid crystal cell) through an adhesive layer (thickness: 1 μm). Sticked.

  The liquid crystal panel A thus produced has an E mode configuration shown in FIG. The liquid crystal panel A was combined with a backlight unit to produce a liquid crystal display device A. The liquid crystal display device A immediately after turning on the backlight had good display uniformity over the entire surface. After 30 minutes had passed since the backlight was turned on, the color shift amount (Δu′v ′) in the oblique direction of the liquid crystal display device A was measured. The characteristics of the obtained liquid crystal display device A are shown in Table 5 below together with the characteristics of Example 2 described later and Comparative Examples 1 and 2. FIG. 9 shows Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° in Example 1 and Comparative Example 1 described later. FIG. 10 shows Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 1 and Comparative Example 1 described later. Δu′v ′ is one of the indexes representing the color shift amount of the liquid crystal display device, and the smaller the value, the better the display characteristics. In the liquid crystal display device A of Example 1, the average value of Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° was 0.075, and the maximum value was 0.099. The average value of Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° was 0.071, and the maximum value was 0.105.

[Comparative Example 1]
A liquid crystal panel X was produced in the same manner as in Example 1 except that the retardation film 2-A obtained in Reference Example 4 was used instead of the retardation film 1-A as the first optical element. . The liquid crystal panel X thus produced has an E mode configuration shown in FIG. The liquid crystal panel X was combined with a backlight unit to produce a liquid crystal display device X. The liquid crystal display device X immediately after turning on the backlight had good display uniformity over the entire surface. The color shift amount (Δu′v ′) in the oblique direction of the liquid crystal display device X was measured 30 minutes after the backlight was kept on. The characteristics of the obtained liquid crystal display device X are as shown in Table 5. FIG. 9 shows Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° in the above-described Example 1 and Comparative Example 1, respectively. FIG. 10 shows Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 1 and Comparative Example 1 described above. In the liquid crystal display device X of Comparative Example 1, the average value of Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° was 0.118, and the maximum value was 0.238. The average value of Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° was 0.143, and the maximum value was 0.243.

[Example 2]
The retardation film 1-B obtained in Reference Example 3 is used as the first optical element on the surface on the viewing side of the liquid crystal cell A obtained in Reference Example 6 via an acrylic pressure-sensitive adhesive layer (thickness: 23 μm). The slow axis was stuck so as to be substantially parallel to the long side of the liquid crystal cell A (0 ° ± 0.5 °). Subsequently, the polarizer P1 obtained in Reference Example 1 is used as the first polarizer through the adhesive layer (thickness 1 μm) on the surface of the retardation film 1-B. It was stuck so as to be substantially parallel to the long side of A (0 ° ± 0.5 °). At this time, the initial alignment direction of the liquid crystal cell A, the slow axis of the retardation film 1-B (first optical element), and the absorption axis of the polarizer P1 (first polarizer) are substantially the same. Parallel. Next, the retardation film 2-B obtained in Reference Example 5 is used as the second optical element through the acrylic pressure-sensitive adhesive layer (thickness: 23 μm) on the backlight side surface of the liquid crystal cell A. The slow axis was pasted so that the long side of the liquid crystal cell A was substantially parallel (0 ° ± 0.5 °). Subsequently, the polarizer P2 obtained in Reference Example 1 is used as the second polarizer through the adhesive layer (thickness 1 μm) on the surface of the retardation film 2-B. It was stuck so as to be substantially orthogonal (90 ° ± 0.5 °) to the long side of A. At this time, the absorption axis of the polarizer P1 and the absorption axis of the polarizer P2 are substantially orthogonal. The retardation film 2-A obtained in Reference Example 4 is used as a protective layer on the outside of the polarizers P1 and P2 (on the side opposite to the liquid crystal cell) through an adhesive layer (thickness: 1 μm). Sticked.

  The liquid crystal panel B thus produced has an E mode configuration shown in FIG. This liquid crystal panel B was combined with a backlight unit to produce a liquid crystal display device B. The liquid crystal display device B immediately after turning on the backlight had good display uniformity over the entire surface. After 30 minutes had passed since the backlight was turned on, the color shift amount (Δu′v ′) in the oblique direction of the liquid crystal display device B was measured. The characteristics of the obtained liquid crystal display device B are as shown in Table 5.

  FIG. 11 shows Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° in Example 2 and Comparative Example 2 to be described later. FIG. 12 shows Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 2 and Comparative Example 2 to be described later. The Δu′v ′ value is one of indices indicating the color shift amount of the liquid crystal display device, and the smaller the value, the better the display characteristics. In the liquid crystal display device B of Example 2, the average value of Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° was 0.068, and the maximum value was 0.110. The average value of Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° was 0.076, and the maximum value was 0.105.

  FIG. 13 shows Y values in all directions (0 ° to 360 °) at a polar angle of 60 ° in Example 2 and Comparative Example 2 to be described later. FIG. 14 shows Y values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 2 and Comparative Example 2 described later. The Y value is one of indexes indicating the amount of light leakage of the liquid crystal display device, and the smaller the value, the better the display characteristics. In the liquid crystal display device B of Example 2, the average value of Y values in all directions (0 ° to 360 °) at a polar angle of 60 ° was 0.59, and the maximum value was 1.23. The average value of the Y values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° was 0.59, and the maximum value was 0.67.

[Comparative Example 2]
A liquid crystal panel Y was produced in the same manner as in Example 2 except that the retardation film 2-A obtained in Reference Example 4 was used instead of the retardation film 1-B as the first optical element. . The liquid crystal panel Y thus produced has an E mode configuration shown in FIG. This liquid crystal panel X was combined with a backlight unit to produce a liquid crystal display device Y. The liquid crystal display device Y immediately after turning on the backlight had good display uniformity over the entire surface. After 30 minutes had passed since the backlight was turned on, the color shift amount (Δu′v ′) in the oblique direction of the liquid crystal display device Y was measured. The characteristics of the obtained liquid crystal display device Y are as shown in Table 5.

  FIG. 11 shows Δu′v ′ values in all directions (0 ° to 360 °) at the polar angle of 60 ° in Example 2 and Comparative Example 2 described above. FIG. 12 shows Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 2 and Comparative Example 2 described above. In the liquid crystal display device Y of Comparative Example 2, the average value of Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° was 0.093, and the maximum value was 0.171. The average value of Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° was 0.091, and the maximum value was 0.107.

  FIG. 13 shows Y values in all directions (0 ° to 360 °) at a polar angle of 60 ° in Example 2 and Comparative Example 2 to be described later. FIG. 14 shows Y values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 2 and Comparative Example 2 described later. The Y value is one of indexes indicating the amount of light leakage of the liquid crystal display device, and the smaller the value, the better the display characteristics. In the liquid crystal display device B of Example 2, the average value of Y values in all directions (0 ° to 360 °) at a polar angle of 60 ° was 1.37, and the maximum value was 3.25. The average Y value of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° was 1.70, and the maximum value was 2.98.

[Evaluation]
As shown in Examples 1 and 2, a first optical element that satisfies specific optical characteristics is disposed between a liquid crystal cell and a first polarizer disposed on one side of the liquid crystal cell, By producing a liquid crystal panel in which the slow axis of one optical element is arranged substantially parallel to the absorption axis of the first polarizer, a liquid crystal display device having a small color shift amount in an oblique direction can be obtained. did it. On the other hand, as shown in Comparative Examples 1 and 2, a liquid crystal panel that does not satisfy the configuration of the liquid crystal panel of the present invention can only obtain a liquid crystal display device having a large color shift amount in an oblique direction. As shown in Example 2, a second optical element satisfying a specific optical element is disposed between a liquid crystal cell and a second polarizer disposed on the other side of the liquid crystal cell, and the first optical element is disposed. By producing a liquid crystal panel in which the slow axis of the element is arranged so as to be substantially parallel or substantially orthogonal to the absorption axis of the first polarizer, the amount of color shift in the oblique direction is further reduced, and the oblique direction A liquid crystal display device having a small amount of light leakage was obtained.

  As described above, according to the liquid crystal panel of the present invention, the amount of color shift in an oblique direction can be reduced, so it can be said that it is extremely useful for improving the display characteristics of a liquid crystal display device. The liquid crystal panel 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 liquid crystal panel by preferable embodiment of this invention. (A) is a schematic perspective view in case the liquid crystal panel of FIG. 1 employ | adopts E mode, (b) is a schematic perspective view in case the liquid crystal panel of FIG. 1 employ | adopts O mode. It is a schematic diagram which shows the concept of the typical manufacturing process of the polarizer used for this invention. It is a schematic sectional drawing of the liquid crystal panel by another embodiment of this invention. (A) is a schematic perspective view in case the liquid crystal panel of FIG. 4 employ | adopts E mode, (b) is a schematic perspective view in case the liquid crystal panel of FIG. 4 employ | adopts O mode. It is a schematic diagram which shows the concept of the typical manufacturing process of the retardation film used for a 2nd optical element. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. (A) is a schematic perspective view of the liquid crystal panel used in Example 1, (b) is a schematic perspective view of the liquid crystal panel used in Comparative Example 1. 7 is a graph showing measurement results of Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° in Example 1 and Comparative Example 1. 6 is a graph showing measurement results of Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 1 and Comparative Example 1. 10 is a graph showing measurement results of Δu′v ′ values in all directions (0 ° to 360 °) at a polar angle of 60 ° in Example 2 and Comparative Example 2. 6 is a graph showing measurement results of Δu′v ′ values of polar angles (0 ° to 78 °) at an azimuth angle of 45 ° in Example 2 and Comparative Example 2. It is a graph showing the measurement result of the Y value of all the directions (0 degrees-360 degrees) in the polar angle of 60 degrees of Example 2 and Comparative Example 2. It is a graph showing the measurement result of the Y value of the polar angle (0 degree-78 degree) in the azimuth angle of 45 degrees of Example 2 and Comparative Example 2. 10 is a schematic perspective view of a liquid crystal panel used in Comparative Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal cell 11, 11 'Board | substrate 12 Liquid crystal layer 21 1st polarizer 22 2nd polarizer 30 1st optical element 40 2nd optical element 60, 60' Protective layer 70, 70 'Surface treatment layer 80 Backlight unit 81 Back Light 82 Reflective film 83 Diffuser plate 84 Prism sheet 85 Brightness enhancement film 100, 101, 102 Liquid crystal panel 200 Liquid crystal display device 300 Feeding section 310 Iodine aqueous solution bath 320 Bath of aqueous solution containing boric acid and potassium iodide 330 Potassium iodide Aqueous solution bath 340 Drying means 350 Polarizer 360 Winding part 401, 403, 405 Feeding part 414, 416, 419 Winding part 404, 406 Shrinkable film 407, 408 Laminating roll 409 Heating means

Claims (9)

A liquid crystal cell, a first polarizer disposed on one side of the liquid crystal cell, a second polarizer disposed on the other side of the liquid crystal cell, and between the first polarizer and the liquid crystal cell And at least a first optical element disposed on
The liquid crystal cell includes a liquid crystal layer including liquid crystal molecules aligned in a homogeneous arrangement in the absence of an electric field, and the initial alignment direction is substantially the same as the absorption axis of the first polarizer and the slow axis of the first optical element. Parallel,
The first optical element is a single retardation film satisfying the following formulas (1) and (2), and is attached to the first polarizer and the liquid crystal cell via an adhesive layer, and the retardation phase thereof. A liquid crystal panel having an axis arranged so as to be substantially parallel to the absorption axis of the first polarizer:
10 nm <Re [590] (1)
| Rth [590] -Re [590] | <10 nm (2)
However, Re [590] and Rth [590], respectively, Ri retardation value der retardation value and the thickness direction in a plane measured with light having a wavelength of 590nm at 23 ℃, Rth [590] is the wavelength 590nm When the refractive index in the slow axis direction and the thickness direction of the optical element is nx and nz, respectively, and d (nm) is the thickness of the optical element, the formula: Rth [590] = (nx−nz) × d.   The liquid crystal panel according to claim 1, wherein the thickness of the first optical element is 50 μm to 200 μm. Wherein the first optical element is a retardation fill Muma other containing a norbornene-based resin is a retardation film containing a cellulose resin, a liquid crystal panel according to claim 1 or 2. A second optical element between the liquid crystal cell and the second polarizer;
The second optical element satisfies the following formulas (3) and (4), and is arranged so that its slow axis is substantially parallel or substantially perpendicular to the absorption axis of the second polarizer. The liquid crystal panel according to any one of claims 1 to 3, wherein
50 nm ≦ Rth [590] ≦ 200 nm (3)
−200 nm ≦ Rth [590] −Re [590] ≦ 80 nm (4)
However, Re [590] and Rth [590], respectively, Ri retardation value der retardation value and the thickness direction in a plane measured with light having a wavelength of 590nm at 23 ℃, Rth [590] is the wavelength 590nm When the refractive index in the slow axis direction and the thickness direction of the optical element is nx and nz, respectively, and d (nm) is the thickness of the optical element, the formula: Rth [590] = (nx−nz) × d.   5. The liquid crystal panel according to claim 4, wherein a ratio Rth [590] / Re [590] of the retardation value in the thickness direction of the second optical element to the in-plane retardation value is 0.3 to 0.7.   The liquid crystal panel according to claim 4 or 5, wherein the second optical element is a single retardation film, and is attached to the second polarizer and the liquid crystal cell via an adhesive layer.   The liquid crystal panel according to any one of claims 4 to 6, wherein the second optical element includes a retardation film containing a norbornene resin and / or a retardation film containing a cellulose resin.   A liquid crystal television comprising the liquid crystal panel according to claim 1.   A liquid crystal display device comprising the liquid crystal panel according to claim 1.