JP2007279127A - Liquid crystal panel, liquid crystal television, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal panel which has a high contrast ratio in an oblique direction and a small amount of color shift in the oblique direction and has excellent display characteristics, and a liquid crystal display device. <P>SOLUTION: The liquid crystal panel 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; a negative C plate disposed between the liquid crystal cell and the first polarizer; a phase difference element disposed between the liquid crystal cell and the negative C plate; and an isotropic optical element disposed between the liquid crystal cell and the second polarizer. The direction of an absorption axis of the first polarizer is substantially orthogonal to that of the second polarizer, and the phase difference element has an index ellipsoid having a relation of nx>nz>ny and has an Re[590]<SB>z</SB>of <350 nm, and the direction of a lagging axis of the phase difference element is substantially parallel with the direction of the absorption axis of the first polarizer. <P>COPYRIGHT: (C)2008,JPO&INPIT

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.

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

Conventionally, various retardation films are used in liquid crystal display devices. For example, a method for improving the contrast ratio in an oblique direction by disposing a retardation film (so-called Z film) having a relationship of nx>nz> ny on one side of an in-plane switching (IPS) liquid crystal cell is disclosed. (For example, see Patent Document 1). However, with such a technique, the contrast ratio in the oblique direction and the color shift amount in the oblique direction are not sufficiently improved, and the display characteristics of the obtained liquid crystal display device satisfy the level required for large color television applications. Not.
JP-A-11-305217

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a liquid crystal panel having excellent display characteristics with a high contrast ratio in the oblique direction and a small amount of color shift in the oblique direction, and a liquid crystal display device Is to provide.

  The inventors of the present invention have examined the cause of insufficient display characteristics in a liquid crystal panel (liquid crystal display device) using a conventional Z-film, and found that a polarizer or a liquid crystal cell between the polarizer and the liquid crystal cell. Based on the idea that the types of constituent members to be arranged and the phase difference value may act in a complex manner and adversely affect the display characteristics. (1) The liquid crystal cell is arranged on one side of the liquid crystal cell. A negative C plate is disposed between the first polarizer and (2) a specific retardation element is disposed between the liquid crystal cell and the negative C plate, and (3) the liquid crystal cell and the other one. An isotropic optical element between the second polarizer and the second polarizer, and (4) the absorption axis direction of the first polarizer and the absorption axis direction of the second polarizer (5) the retardation axis direction of the retardation element and the absorption axis direction of the first polarizer are substantially When parallel, the light leakage in the oblique direction in the black display is greatly reduced, and the display characteristics (contrast ratio in the oblique direction and the color shift amount in the oblique direction) are compared with the conventional liquid crystal panel (liquid crystal display device). It has been found that a liquid crystal panel that is remarkably superior can be provided.

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 liquid crystal cell. A negative C plate disposed between the liquid crystal cell and the first polarizer, a phase difference element disposed between the liquid crystal cell and the negative C plate, the liquid crystal cell and the second polarizer, An isotropic optical element disposed between the first polarizer, the absorption axis direction of the first polarizer is substantially perpendicular to the absorption axis direction of the second polarizer, and the retardation element The refractive index ellipsoid has a relationship of nx>nz> ny, Re [590] _Z is less than 350 nm, and the slow axis direction of the retardation element is the absorption axis direction of the first polarizer. Are substantially parallel.

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

In a preferred embodiment, Rth [590] _NC of the negative C plate is more than 10 nm and not more than 200 nm.

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

  In a preferred embodiment, the Nz coefficient of the retardation element is less than 0.6.

  In a preferred embodiment, the retardation element includes a retardation film containing a norbornene resin.

In a preferred embodiment, the Re _{[590] Z} of the phase difference element, a difference between the negative C plate of _{Rth [590] NC (Re [} 590] Z -Rth [590] NC) is at 250~300nm is there.

  In a preferred embodiment, the isotropic optical element includes a polymer film containing at least one resin selected from an acrylic resin, a cellulose resin, and a cycloolefin resin as a main component.

  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.

  According to the present invention, it is possible to provide a liquid crystal panel and a liquid crystal display device having excellent display characteristics with a high contrast ratio in the oblique direction and a small amount of color shift in the oblique direction.

  Such an effect is obtained by using a liquid crystal panel as a configuration of a liquid crystal cell, a first polarizer disposed on one side of the liquid crystal cell, and a second polarizer disposed on the other side of the liquid crystal cell. A negative C plate disposed between the liquid crystal cell and the first polarizer, a retardation element having specific optical characteristics disposed between the liquid crystal cell and the negative C plate, An isotropic optical element disposed between the liquid crystal cell and the second polarizer, and an absorption axis direction of the first polarizer and an absorption axis direction of the second polarizer Are made substantially perpendicular to each other, and the slow axis direction of the retardation element and the absorption axis direction of the first polarizer are substantially parallel to each other.

In the present invention, the suffix “NC” is attached to the negative C plate, and the suffix “Z” is attached to the phase difference element.
In this specification, “substantially orthogonal” means that an angle formed by two axes (for example, an absorption axis of a polarizer and an absorption axis of another polarizer) is 90 ° ± 2.0 °. And preferably 90 ° ± 1.0 °, more preferably 90 ° ± 0.5 °.
In this specification, “substantially parallel” means that the angle formed by two axes (for example, the slow axis of the retardation film and the absorption axis of the polarizer) is 0 ° ± 2.0 °. And preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °.

<< A. Overview of the entire LCD panel >>
FIG. 1 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. FIG. 2 is a schematic perspective view of the liquid crystal panel. It should be noted that, for the sake of easy understanding, the ratios of the vertical, horizontal, and thickness of the constituent members in FIGS. 1 and 2 are described differently from actual ones. The liquid crystal panel 100 includes a liquid crystal cell 10, a first polarizer 21 disposed on one side of the liquid crystal cell, a second polarizer 22 disposed on the other side of the liquid crystal cell 10, Negative C plate 30 and retardation element 40 disposed between the liquid crystal cell 10 and the first polarizer 21, disposed between the liquid crystal cell 10 and the second polarizer 22, etc. The negative C plate 30 is disposed between the first polarizer 21 and the phase difference element 40.

  The absorption axis direction of the first polarizer is disposed so as to be substantially orthogonal to the absorption axis direction of the second polarizer.

  The slow axis direction of the retardation element is substantially parallel to the absorption axis direction of the first polarizer.

  Thus, by using a specific optical element in a specific positional relationship, the function of each optical element is exhibited synergistically, and as a result, light leakage in an oblique direction in black display is greatly reduced, A liquid crystal panel (liquid crystal display device) having significantly superior display characteristics as compared with a conventional liquid crystal panel can be obtained.

  In the illustrated example, the first polarizer 21, the negative C plate 30, and the retardation element 40 are disposed on the viewing side of the liquid crystal cell 10. It may be arranged on the side. Practically, any appropriate protective layer (not shown) may be disposed outside the first polarizer 21 and the second polarizer 22.

  The liquid crystal panel of the present invention is not limited to the illustrated example, and any constituent member such as any film or adhesive layer (preferably having isotropic optical characteristics) is provided between the constituent members. Can be arranged. Hereinafter, the constituent members of 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 12 and a liquid crystal layer 13 as a display medium sandwiched between the substrates 11 and 12. One substrate (active matrix substrate) 12 includes a switching element (typically a TFT) (not shown) for controlling the electro-optical characteristics of the liquid crystal and a scanning line (not shown) for supplying a gate signal to the switching element. ) And a signal line for supplying a source signal (not shown), a pixel electrode and a counter electrode (both not shown). The other substrate (color filter substrate) 11 is provided with a color filter (not shown) and a black matrix (not shown). Note that the color filter may be provided on the active matrix substrate 12 side. A distance (cell gap) between the substrates 11 and 12 is controlled by a spacer (not shown). For example, an alignment film (not shown) made of polyimide is provided on the side of the substrates 11 and 12 in contact with the liquid crystal layer 13.

  Preferably, the liquid crystal layer 13 includes nematic liquid crystal that is homogeneously aligned 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. Examples of the driving mode using the liquid crystal layer exhibiting such a refractive index distribution include an in-plane switching (IPS) mode and a fringe field switching (FFS) mode.

  The IPS mode uses a voltage-controlled birefringence (ECB) effect to generate a nematic liquid crystal that is homogeneously aligned in the absence of an electric field, for example, between a counter electrode and a pixel electrode formed of metal. The substrate is made to respond with an electric field (also referred to as a transverse electric field) parallel to the substrate. More specifically, Techno Times Publishing “Monthly Display July” p. 83-p. 88 (1997 edition) and “Liquid Crystal vol.2 No. 4” published by the Japanese Liquid Crystal Society. 303-p. 316 (1998 edition), in the normally black method, there is no electric field when the upper and lower polarizing plates are arranged orthogonally so that the major axis of the liquid crystal molecules coincides with the absorption axis of the incident-side polarizing plate. When the display is completely black and there is an electric field, the liquid crystal molecules can rotate while keeping parallel to the substrate, thereby obtaining a transmittance corresponding to the rotation angle. The IPS mode includes a super-in-plane switching (S-IPS) mode and an advanced super-in-plane switching (AS-IPS) mode using a zigzag electrode. 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, nematic liquid crystal that is homogeneously aligned in the absence of an electric field, for example, a counter electrode and a pixel electrode formed of a transparent conductor. The substrate is caused to respond with an electric field parallel to the substrate generated in step (also referred to as a transverse electric field). Note that the lateral 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, SID (Society for Information Display) 2001 Digest, p. 484-p. As described in 487 and JP 2002-031812, in the normally black system, the upper and lower polarizing plates are arranged orthogonally so that the major axis of the liquid crystal molecules coincides with the absorption axis of the incident side polarizing plate. When there is no electric field, the display is completely black, and when there is an electric field, the liquid crystal molecules can rotate while keeping parallel to the substrate, thereby obtaining a transmittance corresponding to the rotation angle. The FFS mode includes an advanced fringe field switching (A-FFS) mode and an ultra fringe field switching (U-FFS) mode using a zigzag electrode. 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 homogeneously aligned nematic liquid crystal is a liquid crystal in which the alignment vector of the nematic liquid crystal molecules is aligned parallel and uniformly to the substrate plane as a result of the interaction between the aligned substrate and the nematic liquid crystal. Say. In the present specification, the homogeneously aligned nematic liquid crystal includes a case where the alignment vector is slightly tilted with respect to the substrate plane (that is, the nematic liquid crystal has a pretilt). In this case, the pretilt angle is preferably 10 ° or less. This is because the contrast ratio is kept high and good display characteristics can be obtained.

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 and transmittance of the liquid crystal, Usually, it is preferably 0.05 to 0.30.

  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. Within the above range, the response time can be shortened and good display characteristics can be obtained.

<< C. Polarizer
In this specification, a polarizer means a film that can be converted from natural light or polarized light into arbitrary polarized light. Any appropriate polarizer can be adopted as the polarizer used in the present invention. For example, those that convert natural light or polarized light into linearly polarized light are preferably used. Preferably, the polarizer has a function of passing one of the polarized components when incident light is divided into two orthogonal polarized components, and absorbs the other polarized component, Those having at least one function selected from the functions of reflection and scattering are used.

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

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

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

<< C-2. Means for arranging polarizers >>
Referring to FIG. 2, any appropriate method may be adopted as a method of arranging the first polarizer 21 and the second polarizer 22 depending on the purpose. Preferably, the first polarizer 21 is attached to the surface of the negative C plate 30 by providing an adhesive layer (not shown) on the surface facing the liquid crystal cell 10. Preferably, the second polarizer 22 is provided with an adhesive layer (not shown) on the surface facing the liquid crystal cell 10 and is attached to the surface of the isotropic optical element 50. By doing so, the contrast can be increased when used in a liquid crystal display device. In the present specification, the “adhesive layer” means that the surfaces of adjacent optical elements and polarizers are joined and integrated with an adhesive force and an adhesive time that do not adversely affect practical use. If there is, there is no particular limitation. Specific examples of the adhesive layer include an adhesive layer and an anchor coat layer. The adhesive layer may have a multilayer structure in which an anchor coat layer is formed on the surface of an adherend and an adhesive layer is formed thereon.

  Preferably, the first polarizer 21 is disposed such that the absorption axis thereof is substantially orthogonal to the absorption axis of the second polarizer 22 facing the first polarizer 21. As the degree of deviation from the substantially orthogonal angle range increases, the contrast ratio in the front and oblique directions tends to decrease when used in a liquid crystal display device.

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

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

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

<< C-3. Optical film used for polarizers >>
The optical film used for the polarizer is not particularly limited. For example, a stretched film of a polymer film mainly containing a polyvinyl alcohol resin containing iodine or a dichroic dye, US Pat. No. 5,523, No. 863, an O-type polarizer in which a liquid crystalline composition containing a dichroic material and a liquid crystalline compound is aligned in a certain direction, and disclosed in US Pat. No. 6,049,428. And an E-type polarizer in which lyotropic liquid crystal is aligned in a certain direction.

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

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

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

  The saponification degree of the polyvinyl alcohol-based resin is preferably 90.0 to 99.9 mol% from the viewpoint of durability of the polarizer.

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

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

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

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

  Any appropriate type of surfactant can be adopted as the type of the surfactant, and specific examples include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. In the present invention, a nonionic surfactant is preferably used. Specific examples of the nonionic surfactant include lauric acid diethanolamide, coconut oil fatty acid diethanolamide, coconut oil fatty acid monoethanololamide, lauric acid monoisopropanolamide, oleic acid monoisopropanolamide, and the like. Not. In the present invention, lauric acid diethanolamide is preferably used.

  The amount of the surfactant used is preferably more than 0 and 5 parts by weight or less, more preferably more than 0 and 3 parts by weight or less, and most preferably 0 with respect to 100 parts by weight of the polyvinyl alcohol resin. And not more than 1 part by weight. By setting it as the above range, dyeability and stretchability can be improved.

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

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

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

  Any appropriate moisture content can be adopted as the moisture content of the polarizer. Preferably, the moisture content is 5% to 40%.

<< D. Negative C plate >>
In this specification, the “negative C plate” means that the in-plane main refractive index is nx (slow axis direction), ny (fast axis direction), and the refractive index in the thickness direction is nz. A negative uniaxial optical element whose distribution satisfies nx = ny> nz. Ideally, a negative uniaxial optical element whose refractive index distribution satisfies nx = ny> nz has an optical axis in the normal direction. In the present specification, nx = ny includes not only the case where nx and ny are completely the same, but also the case where nx and ny are substantially the same. Here, “when nx and ny are substantially the same” means, for example, that the in-plane retardation value (Re [590]) measured with light having a wavelength of 590 nm at 23 ° C. is 10 nm or less. Including things. Note that Re [590] of the optical element will be described later. The negative C plate is used together with a retardation element described later, and a liquid crystal panel (liquid crystal display device) caused by a retardation value of a polarizer or a constituent member disposed between the polarizer and the liquid crystal cell. ) Is used to reduce light leakage in an oblique direction in black display.

  Referring to FIGS. 1 and 2, the negative C plate 30 is disposed between the first polarizer 21 and the phase difference element 40. According to such an embodiment, the negative C plate 30 also serves as a protective layer on the liquid crystal cell side of the first polarizer 21, and the polarizing element of the present invention is, for example, in a hot and humid environment. Even when used in a liquid crystal display device, the uniformity of the display screen can be maintained for a long time.

<< D-1. Optical characteristics of negative C plate >>
In this specification, Re [590] refers to an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C. In this specification, “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 is a retardation film. Means a in-plane retardation value of the entire laminate. Re [590] represents the refractive index in the slow axis direction and the fast axis direction of the optical element (or retardation film) at a wavelength of 590 nm as nx and ny, respectively, and d (nm) is the optical element (or retardation film). ) Can be obtained by the formula: Re [590] = (nx−ny) × d. The slow axis means the direction in which the in-plane refractive index is maximum.

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

  In this specification, Rth [590] refers to a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C. Rth [590] represents the refractive index in the slow axis direction and thickness direction of the optical element (or retardation film) at a wavelength of 590 nm as nx and nz, respectively, and d (nm) is the thickness of the optical element (or retardation film). Then, it can be obtained by the formula: Rth [590] = (nx−nz) × d. The slow axis refers to the direction in which the in-plane refractive index is maximum.

The Rth [590] _NC of the negative C plate used in the present invention is preferably more than 10 nm and not more than 200 nm, more preferably 20 nm to 200 nm, still more preferably 20 nm to 150 nm, and particularly preferably 30 nm to 100 nm. By setting it as the above range, the function of each optical element is exhibited synergistically, the contrast ratio in the oblique direction of the liquid crystal display device can be increased, and the color shift amount in the oblique direction can be reduced.

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

Re = (nx−ny) × d (i)
R40 = (nx−ny ′) × d / cos (φ) (ii)
(Nx + ny + nz) / 3 = n0 (iii)
Rth = (nx−nz) × d (iv)
φ = sin ⁻¹ [sin (40 °) / n0]
... (v)
ny ′ = ny × nz [ny ² × sin ² (φ) + nz ² × cos ² (φ)] ^1/2 (vi)

<< D-2. Means for placing negative C plate >>
Referring to FIG. 2, any appropriate method may be adopted as a method of arranging the negative C plate 30 depending on the purpose. Preferably, the negative C plate 30 is provided with an adhesive layer (not shown) on both sides thereof, and is attached to the first polarizer 21 and the retardation element 40. In this way, by filling the gaps between the optical elements with the adhesive layer, the optical axes of the optical elements can be prevented from shifting when they are incorporated into a liquid crystal display device, or the optical elements can be rubbed and damaged. Can be prevented. Further, it is possible to reduce the adverse effects of reflection and refraction generated at the interface between the layers of each optical element, and to increase the contrast ratio in the front and oblique directions of the liquid crystal display device.

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

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

  In the negative C plate 30, when nx and ny are completely the same, no retardation value is generated in the plane, so that the slow axis is not detected, and the absorption axis and position of the first polarizer 21 are not detected. The phase difference element 40 may be arranged independently of the slow axis. Even if nx and ny are substantially the same, a slow axis may be detected if nx and ny are slightly different. In this case, the negative C plate 30 is preferably arranged so that its slow axis is substantially parallel to or substantially perpendicular to the absorption axis of the first polarizer 21. As the degree of deviation from the substantially parallel or substantially orthogonal angle range increases, the contrast ratio in the front and oblique directions tends to decrease when used in a liquid crystal display device.

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

Rth [590] of the retardation film used for the negative C plate can be appropriately selected depending on the number of retardation films used. For example, when the negative C plate is composed of the retardation film alone, it is preferable that Rth [590] of the retardation film is equal to Rth [590] _NC of the negative C plate. Accordingly, the retardation value of the adhesive layer used when the negative C plate is laminated on the first polarizer and the retardation element is preferably as small as possible. For example, when the negative C plate is a laminate including two or more retardation films, the sum of Rth [590] of each retardation film is equal to Rth [590] _NC of the negative C plate. It is preferable to design to be equal. Specifically, when a negative C plate having a Rth [590] _NC of 100 nm is prepared by laminating two retardation films, the Rth [590] of each retardation film may be 50 nm. it can. Alternatively, Rth [590] of one retardation film can be set to 30 nm, and Rth [590] of the other retardation film can be set to 70 nm. Further, Rth [590] of one retardation film may be −10 nm, and Rth [590] of the other retardation film may be 110 nm. When two retardation films are laminated, it is preferable to arrange the retardation films so that the slow axes of the respective retardation films are orthogonal to each other. This is because Re [590] can be reduced. Here, for the sake of simplicity, only the case where the number of retardation films is two or less is shown, but it goes without saying that the present invention can also be applied to a laminate including three or more retardation films.

  The overall thickness of the negative C plate is, for example, 20 μm to 100 μm, although it varies depending on the configuration. By setting it as said range, the optical element excellent in optical uniformity can be obtained.

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

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

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

  Preferably, the negative C plate used in the present invention includes a polymer film mainly composed of a thermoplastic resin. More preferably, the thermoplastic resin is a polymer film containing an amorphous polymer as a main component. Amorphous polymers have the advantage of excellent transparency. The polymer film containing the thermoplastic resin as a main component may or may not be stretched.

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

  Examples of the thermoplastic resin include polyolefin resin, cycloolefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polymethyl methacrylate, polyacetic acid General-purpose plastics such as vinyl and polyvinylidene chloride resins; general-purpose engineering plastics such as polyamide-based resins, polyacetal-based resins, polycarbonate-based resins, modified polyphenylene ether-based resins, polybutylene terephthalate-based resins, polyethylene terephthalate-based resins; polyphenylene sulfide-based resins , Polysulfone resin, polyethersulfone resin, polyetheretherketone resin, polyarylate resin, liquid crystalline resin, polyamideimide resin, Polyimide-based resins, super engineering plastics such as polytetrafluoroethylene-based resin. Said thermoplastic resin is used individually or in combination of 2 or more types. The thermoplastic resin can be used after any appropriate polymer modification. Examples of the polymer modification include modifications such as copolymerization, crosslinking, molecular terminals, and stereoregularity.

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

  The thermoplastic resin preferably has a weight average molecular weight (Mw) measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably 25,000 to 400,000, more preferably 30,000 to 200, 000, particularly preferably in the range of 40,000 to 100,000. When the weight average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

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

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

  The polymer film containing the thermoplastic resin as a main component may further contain any appropriate additive. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. Etc. The kind and amount of the additive used can be appropriately set according to the purpose. For example, the amount of the additive used is preferably more than 0 and 20 parts by weight or less, more preferably more than 0 and 10 parts by weight or less, and most preferably 0 with respect to 100 parts by weight of the thermoplastic resin. More than 5 parts by weight or less.

  The negative C plate may include a stretched polymer film mainly composed of a thermoplastic resin. In this specification, the “stretched film” refers to a plastic film in which tension is applied to an unstretched film at an appropriate temperature, or tension is further applied to a previously stretched film to increase molecular orientation in a specific direction. . Any appropriate stretching method may be employed as a method of stretching a polymer film containing a thermoplastic resin as a main component. Specific examples include a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, and a longitudinal and transverse sequential biaxial stretching method. As the stretching means, any suitable stretching machine such as a roll stretching machine, a tenter stretching machine, and a biaxial stretching machine can be used. Specific examples of preferable thermoplastic resins used for the stretched film include norbornene resins. Details of the norbornene resin will be described later.

  When performing the above-mentioned heat stretching, the temperature may be continuously changed or may be changed stepwise. Further, the stretching process may be divided into two or more times, and stretching and shrinkage (relaxation) may be combined. The stretching direction may be the film longitudinal direction (MD direction) or the width direction (TD direction). Preferably, in order to reduce the in-plane retardation value (Re [590]), the stretched polymer film mainly composed of the thermoplastic resin is, for example, TD when stretched in the MD direction. The film is stretched in two opposite directions, such as in the direction. Re [590] and Rth [590] of the stretched polymer film containing the thermoplastic resin as a main component are appropriately adjusted depending on the retardation value and thickness before stretching, the stretching ratio, the stretching temperature, and the like. 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.

  The temperature in the temperature control means (also referred to as the stretching temperature) when stretching the polymer film containing the thermoplastic resin as a main component depends on the target retardation value, the type and thickness of the polymer film used, etc. It can be appropriately selected. Preferably, it is performed in the range of Tg + 1 ° C. to Tg + 30 ° C. with respect to the glass transition point (Tg) of the polymer film. This is because the retardation value tends to be uniform, and the film is difficult to crystallize (white turbidity). More specifically, the stretching temperature is preferably 100 ° C to 300 ° C, more preferably 120 ° C to 250 ° C. The glass transition temperature (Tg) can be determined by a DSC method according to JIS K 7121: 1987.

  Moreover, the draw ratio at the time of extending | stretching the polymer film which has the said thermoplastic resin as a main component can be suitably selected according to the target phase difference value, the kind of polymer film used, thickness, etc. 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. 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. Re [590] and Rth [590] of the retardation film used for the negative C plate are appropriately adjusted depending on the retardation value and thickness before stretching, the stretching ratio, the stretching temperature, and the like. 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.

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

<< E. Phase difference element >>
Referring to FIGS. 1 and 2, the retardation element 40 is disposed between the liquid crystal cell 10 and the polarizer 20. In the phase difference element 40, the refractive index ellipsoid has a relationship of nx>nz> ny, and Re [590] _Z is less than 350 nm. Preferably, a retardation film containing a norbornene-based resin is included.

<< E-1. Optical characteristics of retardation element >>
Re [590] _Z of the retardation element is less than 350 nm, preferably 240 nm to 340 nm, more preferably 260 nm to 330 nm, still more preferably 280 nm to 330 nm, and particularly preferably 300 nm to 330 nm. By setting it as such a range, the contrast ratio of the diagonal direction of a liquid crystal display device can be raised.

Rth [590] _Z of the retardation element is preferably 35 to 190 nm, more preferably 90 to 190 nm, still more preferably 100 to 180 nm, and particularly preferably 120 to 175 nm.

  In this specification, Rth [590] / Re [590] refers to the ratio between the thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C. and the in-plane retardation value (also referred to as Nz coefficient). . When Rth [590] / Re [590] is smaller than 1, the phase difference element has a relationship of nx> nz> ny.

Rth [590] _Z / Re [590] _Z of the retardation element is preferably less than 0.6, more preferably 0.2 to 0.57, and further preferably 0.3 to 0.55. And particularly preferably 0.4 to 0.55. By bringing the Rth [590] _Z / Re [590] _Z value of the retardation element close to 0.5, it is possible to achieve a characteristic in which the retardation value is substantially constant regardless of the angle. The direction contrast ratio can be increased.

  The wavelength dispersion characteristic of the retardation element is preferably 0.81 to 1.10, and more preferably 0.95 to 1.05. The smaller the chromatic dispersion characteristic is in the above range, the more constant the phase difference value in a wide visible light region. As a result, the contrast ratio in the oblique direction of the liquid crystal display device can be increased, and the color shift amount in the oblique direction can be reduced. In general, the wavelength dispersion characteristic of an optical element refers to the wavelength dependence of a retardation value. The wavelength dispersion characteristic can be represented by a ratio of in-plane retardation values measured with light of wavelengths 480 nm and 590 nm at 23 ° C .: Re [480] / Re [590]. However, Re [480] and Re [590] are in-plane retardation values measured with light of wavelengths 480 nm and 590 nm at 23 ° C., respectively.

And Re _{[590] Z} of the phase difference element, the difference between the Rth _{[590] NC} of the negative C plate _{(Re [590] Z -Rth [} 590] NC) is preferably 250 to 300 nm, more preferably Is 255 to 290 nm, more preferably 260 to 285 nm. By doing so, it is possible to provide a liquid crystal panel and a liquid crystal display device having excellent display characteristics with a high contrast ratio in the oblique direction and a small amount of color shift in the oblique direction.

<< E-2. Arranging means of phase difference element >>
As a method of disposing the retardation element 40 between the liquid crystal cell 10 and the polarizer 20, any appropriate method can be adopted depending on the purpose. Preferably, the retardation element 40 is provided with an adhesive layer or a pressure-sensitive adhesive layer (not shown) on both sides thereof, and is adhered to the polarizer 20 and the liquid crystal cell 10. By doing so, the contrast can be increased when used in a liquid crystal display device.

  The thickness of the adhesive or pressure-sensitive adhesive can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly preferably 10 to 100 μm.

  Any appropriate adhesive or pressure-sensitive adhesive may be adopted as the adhesive or pressure-sensitive adhesive forming the adhesive layer or pressure-sensitive adhesive layer. For example, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate / vinyl chloride copolymer, modified polyolefin, epoxy-based, fluorine-based, natural rubber, synthetic rubber-based polymer A polymer can be appropriately selected and used. In particular, an acrylic pressure-sensitive adhesive is preferably used in that it is excellent in optical transparency, exhibits appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and is excellent in weather resistance and heat resistance.

  The retardation element 40 is arranged so that its slow axis is substantially parallel to the absorption axis of the adjacent polarizer 20. This is because rolls can be produced and bonding becomes easy, and as a result, manufacturing efficiency can be greatly improved. As the degree of deviation from the substantially parallel angle range increases, the degree of polarization of the polarizing plate decreases, and the contrast tends to decrease when used in a liquid crystal display device.

<< E-3. Configuration of retardation element >>
The configuration (laminate structure) of the retardation element is not particularly limited as long as it satisfies the optical characteristics described in the above section E-1. Preferably, a retardation film containing a norbornene resin is included. Specifically, the retardation element may be a retardation film containing a norbornene-based resin alone, or may be a laminate of two or more retardation films. A retardation film and another film ( Preferably, a laminate with an isotropic film) may be used. Preferably, the retardation 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. In the case where the retardation element is a laminate, an adhesive layer, an adhesive layer, and the like may be included. When the laminate includes two or more retardation films and / or two or more other films, these retardation films and / or other films may be the same or different. . The details of the norbornene resin and other films will be described later.

Re [590] of the retardation film used for the retardation element can be appropriately selected depending on the number of the retardation films used. For example, when the retardation element is composed of the retardation film alone, Re [590] of the retardation film is preferably equal to Re [590] _{Z of the} retardation element. Therefore, it is preferable that the retardation of the pressure-sensitive adhesive or adhesive used when the retardation element is laminated on the polarizer or the liquid crystal cell is as small as possible. For example, when the retardation element is a laminate including two or more retardation films, the sum of Re [590] of each retardation film is equal to Re [590] _{Z of the} retardation element. It is preferable to design as follows. Specifically, when two retardation films are used, those having Re [590] of 100 to 175 nm are preferably used. The slow axes of the two retardation films are preferably laminated in parallel.

Rth [590] / Re [590] of the retardation film may be equal to Rth [590] _Z / Re [590] _Z of the retardation element, regardless of the number of retardation films used. preferable. For example, an optical element having Rth [590] / Re [590] = 0.5 and Re [590] of 280 nm is Rth [590] / Re [590] = 0.5 and Re [590] is Two retardation films having a thickness of 140 nm can be obtained by laminating so that the slow axes are parallel to each other.

  The total thickness of the retardation element is preferably 70 to 240 μm, more preferably 80 to 200 μm, and still more preferably 100 to 160 μm. When the retardation element has a thickness in such a range, a liquid crystal display device excellent in optical uniformity can be obtained.

FIG. 4 is a schematic perspective view illustrating a typical example of a preferred embodiment of the retardation element including a relationship with an absorption axis of a polarizer. FIG. 4A shows a case where the retardation element 40 is a single retardation film. FIG. 4A shows a case where the slow axis of the phase difference element 40 and the absorption axis of the polarizer 20 are parallel. According to such a configuration, the retardation element 40 also serves as a protective layer on the liquid crystal cell side of the polarizer, which can contribute to the thinning of the liquid crystal panel. Furthermore, it is also preferable in that the influence of the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight is small. FIG. 4B shows a case where the retardation element 40 is a laminate of one retardation film 31 and one other film (preferably an isotropic film) 36. FIG. 4B shows a case where the slow axis of the retardation film 31 and the absorption axis of the polarizer 20 are parallel. Preferably, the other film 36 is disposed on the polarizer 20 side. According to such a form, the other film functions as a protective layer on the liquid crystal cell side of the polarizer. If an isotropic film is used as the other film, the Rth of the conventional polarizing plate protective layer is obtained. It is possible to eliminate the adverse effects caused by. FIG. 4C shows a case where the retardation element 40 is a laminate of two retardation films 31 and 32, and FIG. 4D shows that the retardation element 40 includes two retardation films 31 and 32. The case where it is a laminated body of 32 and one other film 36 is shown. As described above, Re [590] of the retardation films 31 and 32 is designed such that the sum thereof is equal to Re [590] _Z of the retardation element 40, and Rth [590] / Re [590]. Are designed to be equal to Rth [590] _Z / Re [590] _{Z of the} phase difference element 40. For the sake of simplicity, only the case where the retardation film is 2 sheets or less and the case where the other film is 1 sheet or less is illustrated, but includes 3 or more retardation films and / or 2 or more other films. Needless to say, the present invention can also be applied to a laminate.

<< E-4. Retardation film containing norbornene resin >>
As described above, the retardation element used in the present invention preferably includes a retardation film containing a norbornene resin. This retardation film is a stretched film of a polymer film containing a norbornene resin. As said norbornene-type resin, what has a small photoelastic coefficient and is easy to produce a phase difference is used preferably. Since the norbornene resin film has a smaller photoelastic coefficient than the conventional aromatic polymer film, the polarizer is used when it is used in a liquid crystal display device even if it is directly laminated on the polarizer via an adhesive or an adhesive. It is difficult to cause a shift or non-uniformity of the retardation value due to the shrinkage stress or the heat of the backlight, and good display characteristics can be obtained. One of the great achievements of the present invention is that a retardation film having a relationship of nx>nz> ny and Re [590] _Z of less than 350 nm is actually produced using a norbornene resin. .

The absolute value of the photoelastic coefficient C [590] (m ² / N) of the retardation film is preferably 2.0 × 10 ^{−13 to} 2.0 × 10 ⁻¹¹ , more preferably 5.0 ×. 10 ^{−13 to} 8.0 × 10 ⁻¹² , particularly preferably 2.0 × 10 ^{−12 to} 6.0 × 10 ⁻¹² , and most preferably 2.0 × 10 ^{−12 to} 5.0 ×. ^10-12 . One of the great achievements of the present invention is that a retardation film having such a small photoelastic modulus and a relationship of nx>nz> ny at the same time was actually produced. By using such a retardation film as an optical element of a liquid crystal panel, good display characteristics of the liquid crystal display device can be maintained for a long time.

  The thickness of the retardation film can vary depending on the number of laminated films and the presence or absence of other films. Typically, the total thickness of the obtained retardation element can be set to preferably 70 to 240 μm, and more preferably 70 to 150 μm. For example, when the retardation element is composed of a single retardation film, the thickness of the retardation film is preferably 70 to 240 μm (that is, equal to the entire thickness of the retardation element). Further, for example, when the retardation element is a laminate of two retardation films, the thickness of each retardation film may be any appropriate as long as the sum is a preferable overall thickness of the retardation element. 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 60 to 120 μm, and the thickness of the other retardation film is preferably 60 to 120 μm. is there.

  In this specification, the norbornene-based resin refers to a (co) polymer obtained by using a norbornene-based monomer having a norbornene ring as a part or all of a starting material (monomer). In addition, although the said norbornene-type resin has a norbornene ring (thing which has a double bond in a norbornane ring) as a starting material, it has a norbornane ring in a structural unit in the state of a (co) polymer. However, it does not have to be present. As the norbornene-based resin having no norbornane ring in the structural unit in the (co) polymer state, for example, a monomer that becomes a 5-membered ring by cleavage, typically norbornene, dicyclopentadiene, 5-phenylnorbornene, etc. And derivatives thereof. When the norbornene-based resin is a copolymer, the arrangement state of the repeating units is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be a coalescence.

  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. In addition, the ring-opening (co) polymer of the norbornene-based monomer includes a ring-opening copolymer of one or more norbornene-based monomers and α-olefins, cycloalkenes, and / or non-conjugated dienes. Includes hydrogenated resins. The resin obtained by addition (co) polymerization of the norbornene monomer is subjected to addition copolymerization of one or more norbornene monomers with α-olefins, cycloalkenes, and / or non-conjugated dienes. Resin. Preferably, the retardation film used for the first optical element contains a resin obtained by hydrogenating a ring-opening (co) polymer of a norbornene monomer. This is because a retardation film having excellent molding processability, high uniformity, and a large retardation value can be obtained.

  More preferably, in the retardation film of the present invention, part or all of the structural units have a structure represented by the following general formula (I), the following general formula (II), and / or the following general formula (III). It contains a resin obtained by hydrogenating a ring-opening (co) polymer of a norbornene-based monomer.

  In general formulas (I) (II) and (III), R1 to R14 are each independently hydrogen, halogen, halogenated alkyl group, C1-C4 alkyl group, C1-C4 alkylidene group, C1-C4 alkenyl group. C1-C4 alkoxycarbonyl group, aryl group, aralkyl group, aralkyloxy group, hydroxyalkyl group, cyano group, C4-C10 cycloalkyl group, acyloxy group, or substituted derivatives thereof. n is an integer of 2 or more.

  Particularly preferably, in general formula (I), R1 to R4 each independently represent hydrogen, halogen, a halogenated alkyl group, a C1-C4 alkyl group, a C1-C4 alkylidene group, a C1-C4 alkenyl group, C1- A C4 alkoxycarbonyl group, an aryl group, an aralkyl group, an aralkyloxy group, a C4-C10 cycloalkyl group, or an acyloxy group; n is an integer of 2 or more. In general formula (II), R5 and R6 are each independently hydrogen, halogen, halogenated alkyl group, C1-C4 alkyl group, C1-C4 alkylidene group, C1-C4 alkenyl group, or C1-C4. An alkoxycarbonyl group; n is an integer of 2 or more. In general formula (III), R9 to R14 are each independently hydrogen or a C1-C4 alkyl group. n is an integer of 2 or more.

  Most preferably, in general formula (I), R 1 and R 2 are each independently hydrogen, trifluoromethyl group, methyl group, ethyl group, methylidene group, ethylidene group, vinyl group, propenyl group, methoxycarbonyl group, An ethoxycarbonyl group, a phenyl group, an ethylphenyl group, a benzoyloxy group, a cyclopentyl group, or a cyclohexyl group. R3 and R4 are hydrogen. n is an integer of 2 or more. In general formula (II), R5 and R6 are each independently hydrogen, trifluoromethyl group, methyl group, ethyl group, methylidene group, ethylidene group, vinyl group, propenyl group, methoxycarbonyl group, or ethoxy group. It is a carbonyl group. R7 and R8 are hydrogen. n is an integer of 2 or more. Moreover, in general formula (III), R9-R12 are respectively independently hydrogen or a methyl group. R13 and R14 are hydrogen. n is an integer of 2 or more.

Any appropriate monomer can be selected as the norbornene-based monomer. The norbornene-based monomer is preferably 5-methyl-bicyclo [2.2.1] -hept-2-ene, 5-methyl-bicyclo [2.2.1] -hept-2-ene, 5-methoxy. Carbonyl-bicyclo [2.2.1] -hept-2-ene, 5-methyl-5-methoxycarbonyl-bicyclo [2.2.1] -hept-2-ene, 5-phenyl-bicyclo [2.2 .1] -hept-2-ene, tricyclo [4.3.1 ^2,5 . 0 ^1,6 ] -deca-3,7-diene, tricyclo [4.3.1 ^2,5 . 0 ^1,6 ] -dec-3-ene, tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methoxycarbonyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, or 8-methyl-8-methoxycarbonyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene or a combination thereof. The norbornene-based monomers can be used alone or in combination of two or more. Furthermore, the norbornene-based monomer can be used after any appropriate modification.

  The α-olefins preferably have 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms. Specific examples of α-olefins include ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4,4- Dimethyl-1-pentene, 1-hexene, 3-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicocene and the like. Among these, ethylene is particularly preferable. These α-olefins can be used alone or in combination of two or more. If necessary, other vinyl monomers can be copolymerized within a range not impairing the object of the present invention.

  Examples of the cycloalkenes include cyclobutene, cyclopentene, cyclohexene, 3-methyl-cyclohexene, 3,4-dimethyl-cyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cycloheptene, cyclooctene, 6-bromo- Examples include 3-chloro-4-methylcyclohexene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene and 5,6-dihydrodicyclopentadiene. These cycloalkenes can be used alone or in combination of two or more. If necessary, other vinyl monomers can be copolymerized within a range not impairing the object of the present invention.

  Examples of non-conjugated dienes include 1,4-hexadiene 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and 1,7-octadiene. These non-conjugated dienes can be used alone or in combination of two or more. If necessary, other vinyl monomers can be copolymerized within a range not impairing the object of the present invention.

  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. For example, NTS Co., Ltd. “Optical polymer material development and application technology” 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.

Examples of the ring-opening polymerization catalyst used in the metathesis reaction include metal halides such as ruthenium, rhodium, palladium, osmium, iridium and platinum; a polymerization catalyst comprising a nitrate or acetylacetone compound and a reducing agent; or titanium And a polymerization catalyst comprising a metal halide such as vanadium, zirconium, tungsten, molybdenum, or an acetylacetone compound and an organoaluminum compound. Reaction conditions such as polymerization temperature and pressure can be appropriately selected according to the kind of norbornene-based monomer, the target molecular weight, and the like. In one embodiment, the polymerization temperature is preferably −50 ° C. to 100 ° C., and the polymerization pressure is preferably 0 to 50 kgf / cm ² .

  A resin obtained by hydrogenating the ring-opening (co) polymer of the norbornene-based monomer can be obtained by a hydrogenation reaction performed by blowing hydrogen in the presence of any appropriate hydrogenation catalyst. Specific examples of the hydrogenation catalyst include transition metals such as cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, and tetrabutoxytitanate / dimethylmagnesium. Homogeneous catalyst comprising a combination of compound / alkyl metal compound; heterogeneous metal catalyst such as nickel, palladium, platinum, etc .; nickel / silica, nickel / diatomaceous earth, nickel / alumina, palladium / carbon, palladium / silica, palladium / Examples thereof include a heterogeneous solid supported catalyst in which a metal catalyst such as diatomaceous earth or palladium / alumina is supported on a support.

  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 used in the present invention has a weight average molecular weight (Mw) measured by a gel permeation chromatograph (GPC) method with a toluene solvent, preferably 20,000 to 400,000, more preferably 30,000 to 300,000, particularly preferably 40,000 to 200,000, most preferably 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.

When the norbornene-based resin is obtained by hydrogenating a ring-opening (co) polymer of a norbornene-based monomer, the hydrogenation rate is preferably 90% or more, more preferably 95% or more, most preferably 99% or more. If it is such a range, it will be excellent in heat resistance and light resistance. The hydrogenation rate can be determined from the respective integrated intensity ratios of paraffinic hydrogen and olefinic hydrogen by measuring ¹ H-NMR (500 MHz) of the resin.

  The retardation film used for the retardation element may contain two or more of the norbornene resins. In addition to the norbornene-based resin, other thermoplastic resins may be contained. The content (weight ratio) of the other thermoplastic resin is preferably more than 0 and 50 or less, and more preferably more than 0 and 40 or less with respect to the total solid content 100 of the retardation film. By setting it as the above range, it is possible to obtain a retardation film having a small photoelastic coefficient, good wavelength dispersion characteristics, and excellent durability, mechanical strength, and transparency.

  As said thermoplastic resin, arbitrary appropriate things are selected according to the objective. As a specific example, the thermoplastic resin which can be used as a main component of the polymer film contained in the negative C plate mentioned above is mentioned.

  When the retardation film used for the retardation element is a stretched film of a polymer film containing the norbornene resin and another thermoplastic resin, the other thermoplastic resin is preferably a styrene resin. The styrenic resin is used for the purpose of adjusting the wavelength dispersion characteristic and photoelastic coefficient of the retardation film. In the present specification, the “styrene resin” refers to a polymer obtained by polymerizing a styrene monomer. Examples of the styrenic monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, Examples include 2,5-dichlorostyrene.

  The styrenic resin may be a copolymer obtained by reacting the styrenic monomer with another monomer. Specific examples thereof include styrene / maleimide copolymers, styrene / maleic anhydride copolymers, styrene / methyl methacrylate copolymers, and the like. When the styrenic resin is a copolymer obtained by reacting the styrenic monomer with another monomer, the content of the styrenic monomer is preferably 50 mol% or more and less than 100 mol%, Preferably they are 60 mol% or more and less than 100 mol%, Most preferably, they are 70 mol% or more and less than 100 mol%. Within the above range, a retardation film having a small photoelastic coefficient and excellent wavelength dispersion characteristics can be obtained.

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

  The retardation film used in the present invention can be obtained by laminating a shrinkable film on one or both sides of a polymer film containing a norbornene-based resin and heating and stretching the film by a longitudinal uniaxial stretching method using a roll stretching machine. 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 the refractive index nz in the thickness direction of the retardation film. The method for laminating the shrinkable film on one or both sides of the polymer film is not particularly limited, but an acrylic polymer having an acrylic polymer as a base polymer between the polymer film and the shrinkable film. A method in which an adhesive layer is provided and bonded is preferable because it is easy to manufacture.

  An example of the manufacturing method of the retardation film used for this invention is demonstrated with reference to FIG. FIG. 5 is a schematic diagram showing the concept of a typical production process for the retardation film used in the present invention. For example, the polymer film 502 containing a norbornene-based resin is fed from the first feeding unit 501, and the adhesive roll fed from the second feeding unit 503 on both surfaces of the polymer film 502 by the laminate rolls 507 and 508. The shrinkable film 504 including the agent layer and the shrinkable film 506 including the pressure-sensitive adhesive layer fed from the third feeding portion 505 are attached. A laminate in which a shrinkable film is adhered to both sides of a polymer film is applied with tension in the longitudinal direction of the film by rolls 510, 511, 512 and 513 having different speed ratios while being held at a constant temperature by a heating means 509. The film is subjected to a stretching treatment while being simultaneously given a tension in the thickness direction by the shrinkable film. In the 1st winding part 514 and the 2nd winding part 516, the shrinkable films 504 and 506 are peeled from the stretched laminate together with the pressure-sensitive adhesive layer, and a retardation film (stretched film) 518 is obtained. . The obtained retardation film 518 is wound up by the third winding portion 519.

  The polymer film containing the norbornene resin can be obtained by a casting method or a melt extrusion method from a generally used solution. When mixing and using resin, for example, when producing a film using the casting method, it can stir and mix resin with a solvent in a predetermined ratio, and can use it as a uniform solution. Moreover, when producing a film using a melt extrusion method, resin can be melt-mixed and used in a predetermined ratio. In order to improve the smoothness of the obtained retardation film and obtain good optical uniformity, a casting method from a solution is preferably used.

  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, but are not limited to, 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 2.7 to 9.4%, and the shrinkage ratio in the width direction: S. ¹⁴⁰ (TD) is preferably 4.6 to 20%. More preferably, S ¹⁴⁰ (MD) is 6 to 8%, and S ¹⁴⁰ (TD) is 10 to 15.7%. 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 the shrinkage ratio in the width direction: S ¹⁶⁰ (TD). Is preferably 40 to 52%. If it is said range, the target phase difference value will be obtained and the phase difference film excellent in uniformity can be obtained.

In one embodiment, the difference between the shrinkage in the width direction and the shrinkage in the longitudinal direction at 140 ° C. of the shrinkable film: ΔS ¹⁴⁰ = S ¹⁴⁰ (TD) −S ¹⁴⁰ (MD) is preferably 3.2. % To 10%, more preferably 6% to 9.6%. 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 25% to 35%. 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, and uniform stretching may be difficult. If it is said range, uniform extending | stretching can be performed, without applying excessive load to facilities, such as a drawing machine.

The shrinkage stress: T _A ¹⁴⁰ (TD) per 2 mm width in the width direction at 140 ° C. of the shrinkable film is preferably 0.5 to 0.9 N / 2 mm. Also, the shrinkage stress per unit area at 140 ° C. of shrinkable _film: ^{T B} 140 (TD) is preferably 8.3~15.0N / mm ^2. If it is said range, the target phase difference value will be obtained and uniform extending | stretching can be performed.

The shrinkage stress: T _A ¹⁵⁰ (TD) per 2 mm width in the width direction at 150 ° C. of the shrinkable film is preferably 0.6 to 1.0 N / 2 mm. Also, the shrinkage stress per unit area at 0.99 ° C. of shrinkable _film: ^{T B} 150 (TD) is preferably 10~16.7N / mm ^2. If it is said range, the target phase difference value will be obtained and uniform extending | stretching can be performed.

  The shrinkage rates S (MD) and S (TD) can be determined according to the heating shrinkage rate A method of JIS Z 1712 (however, the heating temperature is 140 ° C or 160 ° C instead of 120 ° C as described above). The difference is that a weight 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 at the center was prepared. To do. The test piece is suspended vertically in an air circulation type thermostatic bath maintained at a temperature of 140 ° C. ± 3 ° C. or 160 ° C. ± 3 ° C. with a weight of 3 g, heated for 15 minutes, taken out, and in a standard state ( Room temperature) for 30 minutes, and then using a caliper specified in JIS B 7507, the distance between the standards was measured to obtain an average value of the five measured values, and S (%) = [(before heating Distance between standards (mm) −Distance between standards after heating (mm)) / Distance between standards before heating (mm)] × 100.

  As the shrinkable film, if it satisfies the object of the present invention, it is used for general packaging, food packaging, pallet packaging, shrinkage label, cap seal, and electrical insulation. A commercially available shrinkable film can also 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. Specific examples of commercially available shrinkable films include Oji Paper Co., Ltd. product name “Alphan Series”, Gunze Co., Ltd. product name “Fancy Top Series”, and Toray Industries, Inc. product name “Trephan Series”. , Santox Co., Ltd., trade name “Santox-OP Series”, Tosero Co., Ltd., trade name “Tosero OP Series”, and the like.

  The temperature in the stretching oven (also referred to as stretching temperature) when the polymer film containing the norbornene-based resin is stretched by heating is equal to or higher than the glass transition temperature (Tg) of the polymer film. It is preferable from the viewpoint that it becomes easy to be uniform and the film is less likely to be crystallized (white turbidity). The stretching temperature is preferably Tg + 1 ° C. to Tg + 30 ° C. of the polymer film.

  Although there is no restriction | limiting in particular as glass transition temperature (Tg) of the said polymer film, Preferably it is 110-185 degreeC, More preferably, it is 120-170 degreeC, Especially preferably, it is 125-150 degreeC. If Tg is 110 ° C. or higher, a film having good thermal stability can be easily obtained. If the temperature is 185 ° C. or lower, in-plane and thickness direction retardation values can be easily controlled by stretching. The glass transition temperature (Tg) can be determined by a DSC method according to JIS K7121.

  The draw ratio at the time of heating and stretching the polymer film is determined from the polymer film composition, the type of volatile component, the residual amount of the volatile component, the retardation value to be designed, etc. Although not limited, for example, 1.05 to 2.00 times is preferably used. The feed rate during stretching is not particularly limited, but is preferably 0.5 m / min or more, more preferably 1 m / min or more, from the mechanical accuracy and stability of the stretching apparatus.

<< F. Laminated optical element >>
In addition to the arrangement means described in the above section D-2 and the above section E-2, the negative C plate and the retardation element described above may be laminated in advance with each optical element. In this specification, “laminated optical element” refers to a laminated body in which a negative C plate and a retardation element are laminated. When producing a laminated optical element, the order in which the negative C plate and the retardation element are laminated is not particularly limited, and any suitable method can be adopted.

  Preferably, the laminated optical element is produced by forming a solidified layer or a cured layer of a liquid crystalline composition on the surface of a polymer film that can function as a retardation element. According to such an embodiment, since the polymer film also serves as a support for the solidified layer or the cured layer of the liquid crystalline composition, the process can be simplified, so that the industrial production of the laminated optical element is possible. Is very advantageous.

<< G. Isotropic optical element >>
In this specification, the “isotropic optical element” means that the in-plane main refractive index is nx, ny, and the refractive index in the thickness direction is nz, and the refractive index distribution satisfies nx = ny = nz. Say things. In the specification, nx, ny and nz include not only the case where they are completely the same, but also the case where nx, ny and nz are substantially the same. Here, “when nx, ny and nz are substantially the same” means, for example, that the in-plane retardation value (Re [590]) is 10 nm or less and the thickness direction retardation value (Rth [ 590]) has an absolute value (| Rth [590] |) of 10 nm or less. The isotropic optical element is used to eliminate the adverse effect on the display characteristics exerted by the retardation value of the liquid crystal cell.

  Referring to FIGS. 1 and 2, the isotropic optical element 50 is disposed between the liquid crystal cell 10 and the second polarizer 22. According to such a form, the isotropic optical element functions as a protective film on the liquid crystal cell side of the polarizer, prevents the polarizer from being deteriorated, and as a result, improves the display characteristics of the liquid crystal panel for a long time. Can be maintained. Preferably, the isotropic optical element 50 and the second polarizer 22 are disposed on the backlight side of the liquid crystal cell 10.

<< G-1. Optical properties of isotropic optical elements >>
Re [590] of the isotropic optical element used in the present invention is preferably as small as possible. This is because the contrast ratio in the front and oblique directions of the liquid crystal display device can be increased. Re [590] is preferably 5 nm or less, and most preferably 3 nm or less. The theoretical lower limit of Re [590] of the isotropic optical element is 0 nm.

  The absolute value (| Rth [590] |) of Rth [590] of the isotropic optical element is preferably as small as possible. This is because the contrast ratio in the oblique direction of the liquid crystal display device can be increased. Rth [590] is preferably 7 nm or less, and most preferably 5 nm or less. Note that the theoretical lower limit of | Rth [590] | of the isotropic optical element is 0 nm. By setting Re [590] and Rth [590] of the isotropic optical element within the above range, the adverse effect due to the retardation value of the isotropic optical element on the display characteristics of the liquid crystal display device is eliminated. At the same time, adverse effects due to the retardation value of the liquid crystal cell (preferably a liquid crystal cell including a liquid crystal layer including a nematic liquid crystal that is homogeneously aligned in the absence of an electric field) can be eliminated.

<< G-2. Isotropic optical element arrangement means >>
Referring to FIG. 2, any appropriate method can be adopted as a method of disposing the isotropic optical element 50 between the liquid crystal cell 10 and the second polarizer 22 depending on the purpose. Preferably, the isotropic optical element 50 is provided with an adhesive layer (not shown) on both sides thereof and is attached to the liquid crystal cell 10 and the second polarizer 22. In this way, by filling the gaps between the optical elements with the adhesive layer, the optical axes of the optical elements can be prevented from shifting when they are incorporated into a liquid crystal display device, or the optical elements can be rubbed and damaged. Can be prevented. Further, it is possible to reduce the adverse effects of reflection and refraction generated at the interface between the layers of each optical element, and to increase the contrast ratio in the front and oblique directions of the liquid crystal display device.

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

  In the isotropic optical element 50, when nx and ny are completely the same, no retardation value is generated in the plane, so that the slow axis is not detected, and the absorption axis of the second polarizer 22 is not detected. Can be arranged independently. Even if nx and ny are substantially the same, a slow axis may be detected if nx and ny are slightly different. In this case, the isotropic optical element 50 is preferably arranged so that its slow axis is substantially parallel to or substantially perpendicular to the absorption axis of the second polarizer 22. As the degree of deviation from the substantially parallel or substantially orthogonal angle range increases, the contrast ratio in the front and oblique directions tends to decrease when used in a liquid crystal display device.

<< G-3. Configuration of isotropic optical element >>
The configuration (laminated structure) of the isotropic optical element is not particularly limited as long as it satisfies the optical characteristics described in the above section G-1. The isotropic optical element may be a single optical film or a laminate of two or more optical films. When the isotropic optical element is a laminate, an adhesive layer for attaching the optical film may be included. As long as the isotropic optical element is substantially optically isotropic, the optical film may be optically substantially isotropic or may have a retardation value. . For example, when two optical films having retardation values are laminated, the optical films are preferably arranged so that their slow axes are perpendicular to each other. By arranging in this way, the in-plane retardation value can be reduced. Moreover, when laminating two optical films having retardation values, it is preferable that the optical films are laminated with optical films having positive and negative retardation values in the thickness direction. By laminating in this way, the retardation value in the thickness direction can be reduced.

  The total thickness of the isotropic optical element is preferably 20 μm to 200 μm, more preferably 20 μm to 180 μm, and particularly preferably 20 μm to 150 μm. By setting it as said range, the optical element excellent in optical uniformity can be obtained.

<< G-4. Optical film used for isotropic optical element >>
Preferably, the optical film used for the isotropic optical element is optically substantially isotropic. In the present specification, “substantially isotropic” means that there is little optical difference depending on the direction three-dimensionally and does not substantially show anisotropic optical properties such as birefringence. Say. Specifically, the refractive index distribution satisfies nx = ny = nz where the in-plane main refractive index is nx, ny, and the refractive index in the thickness direction is nz. In the present specification, nx, ny and nz include not only the case where they are completely the same, but also the case where nx, ny and nz are substantially the same. Here, “when nx, ny, and nz are substantially the same” means, for example, that Re [590] is 10 nm or less and the absolute value of Rth [590] (| Rth [590] |) Including 10 nm or less.

  The thickness of the optical film can be appropriately selected according to the purpose. Preferably they are 20 micrometers-200 micrometers, More preferably, they are 20 micrometers-150 micrometers, Especially preferably, they are 20 micrometers-120 micrometers. If it is said range, the optical film excellent in mechanical strength and optical uniformity can be obtained.

The absolute value (C [590] (m ² / N)) of the photoelastic coefficient of the optical film is preferably 1 × 10 ^{−12 to} 100 × 10 ⁻¹² , and more preferably 1 × 10 ⁻¹² to 50 × 10 ⁻¹² , particularly preferably 1 × 10 ⁻¹² to 30 × 10 ⁻¹² , and most preferably 1 × 10 ⁻¹² to 8 × 10 ⁻¹² . The smaller the absolute value of the photoelastic coefficient, the smaller the deviation and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight when it is used in a liquid crystal display device. A device can be obtained.

  The transmittance of the optical 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 theoretical upper limit of the transmittance is 100%. The upper isotropic optical element preferably has the same transmittance.

  As the material for forming the optical film, a material excellent in transparency, mechanical strength, thermal stability, moisture shielding, etc. is preferably used. Preferably, the isotropic optical element includes a polymer film containing a thermoplastic resin as a main component. More preferably, the thermoplastic resin is a polymer film containing an amorphous polymer as a main component. Amorphous polymers have the advantage of excellent transparency. The polymer film containing the thermoplastic resin as a main component may or may not be stretched.

  Any appropriate method can be adopted as a method of obtaining the optical film. For example, the above-mentioned forming method for obtaining the polymer film contained in the negative C plate can be mentioned. Among these molding methods, the extrusion molding method or the solvent casting method is particularly preferable. This is because the smoothness of the obtained optical film can be improved and good optical uniformity (for example, a retardation value that is small in the plane and in the thickness direction) can be obtained.

  As said thermoplastic resin, arbitrary appropriate things are selected according to the objective. As a specific example, the thermoplastic resin which can be used as a main component of the polymer film contained in the negative C plate mentioned above is mentioned.

  Preferably, the isotropic optical element of the present invention includes a polymer film containing as a main component at least one resin selected from an acrylic resin, a cellulose resin, and a cycloolefin resin. For example, when these thermoplastic resins are formed into a sheet by a solvent casting method, molecules may spontaneously orientate during the evaporation of the solvent. When the retardation value is in-plane and in the thickness direction, a retardation film having a refractive index distribution satisfying a relationship of nx = ny = nz can be obtained by performing secondary processing such as stretching. Specifically, when an optical film having a small refractive index (nz) in the thickness direction is obtained, the film may be stretched or contracted to increase nz, and the in-plane main refractive index (nx) is large. May be stretched or shrunk to reduce nx. The polymer film containing the acrylic resin as a main component can be obtained, for example, by the method described in Example 1 of JP-A No. 2004-198952. The polymer film containing the cellulose resin as a main component can be obtained, for example, by the method described in Example 1 of JP-A-7-112446. Moreover, the polymer film which has cycloolefin resin as a main component can be obtained by the method as described in Unexamined-Japanese-Patent No. 2001-350017.

  Further, the isotropic optical element of the present invention is a polymer mainly composed of a resin composition containing a thermoplastic resin having a negative intrinsic birefringence value and a thermoplastic resin having a positive intrinsic birefringence value. A film may be included. When a blend film containing a thermoplastic resin having a negative intrinsic birefringence value and a thermoplastic resin having a positive intrinsic birefringence value is used for the isotropic optical element of the present invention, the material is arbitrary. Although an appropriate one can be used, isobutylene / N-methylmaleimide copolymer is preferable as the thermoplastic resin having a negative intrinsic birefringence value, and acrylonitrile is preferable as the thermoplastic resin having a positive intrinsic birefringence value. -Styrene copolymers are preferred. The polymer film mainly composed of the resin composition containing the thermoplastic resin having the negative intrinsic birefringence value and the thermoplastic resin having the positive intrinsic birefringence value is stretched even if stretched. It does not have to be.

  A polymer film mainly composed of a resin composition containing the thermoplastic resin having a negative intrinsic birefringence value and a thermoplastic resin having a positive intrinsic birefringence value, has a negative intrinsic birefringence value The content of the thermoplastic resin is appropriately selected depending on the type of resin used and the like, but is preferably 30 parts by weight to 90 parts by weight with respect to 100 parts by weight of the total solid content of the polymer film. More preferably, it is 40 to 80 parts by weight, and most preferably 50 to 75 parts by weight. Within the above range, a retardation film having excellent mechanical strength and a small retardation value can be obtained.

  The polymer film mainly composed of a resin composition containing the thermoplastic resin having a negative intrinsic birefringence value and the thermoplastic resin having a positive intrinsic birefringence value is optically isotropic. The optical characteristics described in the above section F-1 can be obtained with a single film. These thermoplastic resins, for example, when formed into a sheet by the solvent casting method, have a low tendency to spontaneously orient molecules during the evaporation process of the solvent. A retardation film satisfying the relationship of nx = ny = nz can be obtained without requiring processing. Further, since the expression of the retardation value is small, a stretching process may be performed. The stretching treatment can be carried out for any purpose, such as further improving the mechanical strength or obtaining a wide optical film. A polymer film containing as a main component a resin composition containing the isobutylene / N-methylmaleimide copolymer and acrylonitrile / styrene copolymer can be obtained by the method described in JP-A-5-59193.

<< H. Outline of Liquid Crystal Display Device of the Present Invention >>
FIG. 6 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. The liquid crystal display device 200 includes a liquid crystal panel 100, protective layers 60 and 60 ′ disposed on both sides of the liquid crystal panel, and surface treatment layers 70 and 70 ′ disposed further outside the protective layers 60 and 60 ′. The brightness enhancement film 80, the prism sheet 110, the light guide plate 120, and the backlight 130 are provided outside the surface treatment layer 70 ′ (backlight side).

  As the surface treatment layers 70 and 70 ′, treatment layers subjected to hard coat treatment, antireflection treatment, antisticking treatment, diffusion treatment (also referred to as antiglare treatment), and the like are used.

  In addition, as the brightness enhancement film, a polarization separation film having a polarization selection layer (for example, trade name “D-BEF series” manufactured by Sumitomo 3M Co., Ltd.) and the like are used. By using these optical members, a display device with higher display characteristics can be obtained. In another embodiment, the optical member illustrated in FIG. 6 may be partially omitted depending on the driving mode and application of the liquid crystal cell used, as long as the object of the present invention is satisfied. Alternatively, other optical members can be substituted.

<< I. Application of liquid crystal panel and liquid crystal display device of the present invention >>
The use in which the liquid crystal panel and the liquid crystal display device of the present invention are used is not particularly limited, but is an OA device such as a personal computer monitor, a notebook personal computer, a copy machine, a mobile phone, a clock, a digital camera, a personal digital assistant (PDA), a mobile phone. Portable devices such as game consoles, home electric devices such as video cameras, LCD TVs, and microwave ovens, back monitors, car navigation system monitors, car audio and other in-vehicle devices, commercial store information monitors and other display devices, It can be used for various applications such as 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 following examples and comparative examples. In addition, this invention is not limited only to these Examples. In addition, each analysis method used in the Example is as follows.
(1) Measuring method of single transmittance, polarization degree, hue a value, hue b value of polarizer:
It measured at 23 degreeC using the spectrophotometer [Murakami Color Research Laboratory Co., Ltd. product name "DOT-3"].
(2) Measuring method of molecular weight:
Polystyrene was calculated as a standard sample by the gel permeation chromatograph (GPC) method. Specifically, it measured with the following apparatuses, instruments, and measurement conditions.
Measurement sample: The sample was dissolved in tetrahydrofuran to make a 0.1 wt% solution, allowed to stand overnight, and then filtered using a 0.45 μm membrane filter.
・ Analyzer: “HLC-8120GPC” manufactured by TOSOH
Column: TSKgel Super HM-H / H4000 / H3000 / H2000
Column size: 6.0 mmI. D. × 150mm
-Eluent: Tetrahydrofuran-Flow rate: 0.6 ml / min.
・ Detector: RI
-Column temperature: 40 ° C
・ Injection volume: 20 μl
(3) Measuring method of thickness:
When the thickness was less than 10 μm, measurement was performed using a thin film spectrophotometer [manufactured by Otsuka Electronics Co., Ltd., “instant multiphotometry system MCPD-2000”]. When the thickness was 10 μm or more, measurement was performed using an Anritsu digital micrometer “KC-351C type”.
(4) Measuring method of phase difference values (Re [λ] R40 [λ], Rth [λ]):
It measured with the light of wavelength (lambda) nm in 23 degreeC using the phase difference meter [Oji Scientific Instruments Co., Ltd. product name "KOBRA21-ADH"] based on a parallel Nicol rotation method.
(5) Method for measuring refractive index of film:
It calculated | required from the refractive index measured with the light of wavelength 589nm in 23 degreeC using the Abbe refractometer [The product name "DR-M4" by Atago Co., Ltd.].
(6) Transmittance measurement method:
It measured with the light of wavelength 590nm in 23 degreeC using the ultraviolet visible spectrophotometer [The product name "V-560" by JASCO Corporation].
(7) Photoelastic coefficient measurement method:
Using a spectroscopic ellipsometer [product name “M-220” manufactured by JASCO Corporation], the sample (size 2 cm × 10 cm) is sandwiched at both ends and stress (5 to 15 N) is applied to the phase difference at the center of the sample. The value (23 ° C./wavelength 590 nm) was measured and calculated from the slope of the function of stress and retardation value.
(8) Measuring method of contrast ratio of liquid crystal display device:
After 30 minutes have passed since the backlight was turned on in a dark room at 23 ° C., the Y value of the XYZ display system when a white image and a black image were displayed was measured using a product name “EZ Contrast 160D” manufactured by ELDIM. . The contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) in the white image and the Y value (YB) in the black image. The long side of the liquid crystal panel was set to an azimuth angle of 0 °, and the normal direction was set to a polar angle of 0 °.
(9) Measuring method of color shift amount (ΔE) of liquid crystal display device:
After 30 minutes have passed since the light was turned on in a dark room at 23 ° C., an ELDIM product name “EZ Contrast 160D” was used to display a black image at an azimuth angle of 0 ° to 360 ° and a polar angle of 60 °. Luminance L ^* and color coordinates a ^* and b ^* , defined in the CIE 1976 L ^* a ^* b ^* color space, were measured. The color shift amount (ΔE) in the oblique direction was calculated from the color: {(L ^* ) ² + (a ^* ) ² + (b ^* ) ² } ^1/2 .

[Reference Example 1]: Production of Polarizer Polymer Film Mainly Containing Polyvinyl Alcohol [Kuraray Co., Ltd. Product Name “9P75R (Thickness: 75 μm, Average Polymerization Degree: 2400, Saponification Degree: 99.9 mol% ) "] Was uniaxially stretched 2.5 times while dyeing in a dye bath containing iodine and potassium iodide maintained at 30 ° C. ± 3 ° C. using a roll stretching machine. Next, uniaxial stretching was performed in an aqueous solution containing boric acid and potassium iodide maintained at 60 ° C. ± 3 ° C. while carrying out a crosslinking reaction so as to be 6 times the original length of the polymer film. 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 properties of the obtained polarizers P1 and P2 are shown in Table 1.

[Reference Example 2]: Production of negative C plate A polymer film (trade name “Fujitack UZ” manufactured by Fuji Photo Film Co., Ltd.) mainly composed of a commercially available cellulose resin having a thickness of 40 μm was used as a retardation film 1-A. Used as is. The optical characteristics of the retardation film 1-A are as shown in Table 2.

[Reference Example 3]: Production of retardation element (2-A) Polymer film containing a resin (norbornene resin) obtained by hydrogenating a ring-opening polymer of a norbornene monomer having a thickness of 130 μm [manufactured by JSR Corporation] On both sides of the name “Arton FLZU130D0” (weight average molecular weight = 78200, average refractive index = 1.53, Tg = 135 ° C., Re [590] = 3.0 nm, Rth [590] = 5.0 nm)] Film A (characteristics are as shown in Table 3) was bonded through an acrylic pressure-sensitive adhesive layer (thickness: 15 μm). Then, hold | maintain the film longitudinal direction with a roll extending machine, and it extends | stretches 1.40 time in 152 degreeC air circulation oven, and after extending | stretching, the said shrinkable film A is peeled with the said acrylic adhesive layer. A retardation film 2-A was produced. Table 4 shows the optical properties of the retardation film 2-A.

[Reference Example 4]: Production of retardation element (2-B) A retardation film 2-B was produced in the same manner as in Reference Example 3 except that the stretching temperature was 147 ° C and the stretching ratio was 1.35 times. did. Table 4 shows the optical properties of the retardation film 2-B.

[Reference Example 5]: Production of Retardation Element (2-C) A retardation film 2-C was produced in the same manner as in Reference Example 3 except that the draw ratio was 1.38. Table 4 shows the optical properties of the retardation film 2-C.

[Reference Example 6]: Production of retardation element (2-D) A retardation film 2-D was produced in the same manner as in Reference Example 3 except that the stretching temperature was 147 ° C and the stretching ratio was 1.32. did. Table 4 shows the optical properties of the retardation film 2-D.

[Reference Example 7]: Production of retardation element (2-E) A retardation film 2-E was produced in the same manner as in Reference Example 3 except that the stretching temperature was 145 ° C and the stretching ratio was 1.28 times. did. Table 4 shows the optical characteristics of the retardation film 2-E.

[Reference Example 8]: Production of retardation element (2-F) A retardation film 2-F was produced in the same manner as in Reference Example 3 except that the stretching temperature was 147 ° C and the stretching ratio was 1.38 times. did. Table 4 shows the optical properties of the retardation film 2-F.

[Reference Example 9]: Preparation of isotropic optical element A polymer film [trade name “Fujitack ZRF80S” manufactured by Fuji Photo Film Co., Ltd.] mainly composed of a commercially available cellulose resin having a thickness of 80 μm was used as an optical film 3- As A, it was used as it was. The optical film 3-A has Re [590] = 0 nm and Rth [590] = 2 nm, and is substantially optically isotropic.

[Reference Example 10]: Production of Liquid Crystal Cell From a liquid crystal display device including an IPS mode liquid crystal cell [32V type wide liquid crystal television manufactured by Toshiba Corporation, product name “FACE (model number: 32LC100)”, screen size: 697 mm × 392 mm] The liquid crystal panel was taken out, all the optical films arranged above and below the liquid crystal cell were 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.

[Example 1]
The retardation film 2-A obtained in Reference Example 3 as a retardation element is provided on the surface on the viewing side of the liquid crystal cell A obtained in Reference Example 10 via an acrylic pressure-sensitive adhesive layer (thickness: 23 μm). The slow axis direction was pasted so that the long side direction of the liquid crystal cell A was substantially parallel (0 ° ± 0.5 °). Subsequently, the retardation film 1-A obtained in Reference Example 2 was attached to the surface of the retardation film 2-A as a negative C plate via an acrylic pressure-sensitive adhesive layer (thickness: 23 μm). Next, on the surface of the retardation film 1-A, the polarizer P1 obtained in Reference Example 1 is used as the first polarizer via the adhesive layer (thickness 1 μm), and the absorption axis direction is the above. The liquid crystal cell A was attached so as to be substantially parallel to the long side direction (0 ° ± 0.5 °). At this time, the slow axis direction of the retardation film 2-A (retardation element) and the initial alignment direction of the liquid crystal cell A are substantially orthogonal, and the retardation film 2-A (retardation element). The slow axis direction and the absorption axis direction of the polarizer P1 were substantially parallel.

  Next, the optical film 3-A obtained in Reference Example 9 was attached as an isotropic optical element to the surface on the backlight side of the liquid crystal cell A through an acrylic adhesive (thickness: 23 μm). . Subsequently, on the surface of the optical film 3-A, the polarizer P2 obtained in Reference Example 1 is used as the second polarizer via the adhesive layer (thickness 1 μm), and the absorption axis direction of the polarizer P2 is the liquid crystal. It was stuck so as to be substantially orthogonal (90 ° ± 0.5 °) to the long side direction of cell A. At this time, the absorption axis direction of the polarizer P1 and the absorption axis direction of the polarizer P2 are substantially orthogonal. Further, the initial alignment direction of the liquid crystal cell A and the absorption axis direction of the polarizer P2 are substantially parallel. A triacetyl cellulose film [trade name “Fujitac, manufactured by Fuji Photo Film Co., Ltd.] 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). UZ (thickness 80 μm) ”] was stuck respectively.

  The liquid crystal panel (1A) thus produced has the configuration shown in FIG. This liquid crystal panel (1A) was combined with a backlight unit to produce a liquid crystal display device (1B). The liquid crystal display device (1B) 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 (ΔE) in the oblique direction and the light leakage amount (Y) in the oblique direction of the liquid crystal display device (1B) were measured. Table 5 shows properties of the obtained liquid crystal panel (1A) and liquid crystal display device (1B). Further, FIG. 7 and FIG. 8 show the azimuth angle dependence of the color shift amount (ΔE) when viewed from an oblique direction.

[Example 2]
A liquid crystal panel (2A) and a liquid crystal display device (2B) were produced in the same manner as in Example 1 except that the retardation film 2-B was used as the retardation element. Table 5 shows the properties of the obtained liquid crystal panel (2A) and liquid crystal display device (2B).

[Example 3]
A liquid crystal panel (3A) and a liquid crystal display device (3B) were produced in the same manner as in Example 1 except that the retardation film 2-C was used as the retardation element. Table 5 shows properties of the obtained liquid crystal panel (3A) and liquid crystal display device (3B).

[Example 4]
A liquid crystal panel (4A) and a liquid crystal display device (4B) were produced in the same manner as in Example 1 except that the retardation film 2-D was used as the retardation element. Table 5 shows properties of the obtained liquid crystal panel (4A) and liquid crystal display device (4B).

[Comparative Example 1]
In the retardation film 2-A (retardation element), the absorption axis direction of the first polarizer P1 and the slow axis direction of the retardation film 2-A (retardation element) are substantially orthogonal (90 ° ±). A liquid crystal panel (C1A) and a liquid crystal display device (C1B) were produced in the same manner as in Example 1 except that the liquid crystal panel was arranged so as to be 0.5 °. Table 5 shows the characteristics of the obtained liquid crystal panel (C1A) and liquid crystal display device (C1B). Further, FIG. 7 shows the azimuth angle dependency of the color shift amount (ΔE) when viewed from an oblique direction.

[Comparative Example 2]
A liquid crystal panel (C2A) and a liquid crystal display were prepared in the same manner as in Example 1 except that the optical film 3-A (isotropic element) obtained in Reference Example 9 was used instead of the negative C plate 1-A. A device (C2B) was produced. Table 5 shows the characteristics of the obtained liquid crystal panel (C2A) and liquid crystal display device (C2B). Further, FIG. 7 shows the azimuth angle dependency of the color shift amount (ΔE) when viewed from an oblique direction.

[Comparative Example 3]
The optical film 3-A (isotropic element) obtained in Reference Example 9 was used instead of the negative C plate 1-A, and the retardation film 2-A (retardation element) was used instead of the retardation film 2-A. A liquid crystal panel (C3A) and a liquid crystal display device (C3B) were produced in the same manner as in Example 1 except that E (retardation element) was used. Table 5 shows the characteristics of the obtained liquid crystal panel (C3A) and liquid crystal display device (C3B). Further, FIG. 8 shows the azimuth angle dependency of the color shift amount (ΔE) when viewed from an oblique direction.

[Comparative Example 4]
A liquid crystal panel (C4A) and a liquid crystal display device (C4B) were prepared in the same manner as in Example 1 except that the retardation film 2-F (retardation element) was used instead of the retardation film 2-A (retardation element). ) Was produced. Table 5 shows the characteristics of the obtained liquid crystal panel (C4A) and liquid crystal display device (C4B). Further, FIG. 8 shows the azimuth angle dependency of the color shift amount (ΔE) when viewed from an oblique direction.

[Evaluation]
As shown in Examples 1 to 4, the liquid crystal display device including the liquid crystal panel of the present invention has a significantly higher contrast ratio in the oblique direction and a color shift in the oblique direction than those using the conventional liquid crystal panel. A small amount was obtained. When these liquid crystal display devices were displayed in black in a dark room and visually observed, light leakage and faint coloring were reduced no matter what angle the screen was viewed from. In addition, when a color image was displayed in a dark room and visually observed, a clear color display was obtained without any sense of incongruity from any angle.

  On the other hand, in the liquid crystal display devices of Comparative Examples 1 to 4, only a liquid crystal display device having a low contrast ratio in the oblique direction and a large amount of color shift in the oblique direction could be obtained. When the liquid crystal display devices of Comparative Examples 1 to 4 were displayed in black in a dark room and visually observed, light leakage and weak coloring were observed when the screen was viewed from an oblique direction. Further, when a color image was displayed in a dark room and visually observed, the display color changed depending on the viewing angle, which was very uncomfortable.

  As described above, according to the liquid crystal panel of the present invention, since the contrast ratio in the oblique direction can be increased and the color shift amount in the oblique direction can be reduced, it is extremely useful for improving the display characteristics of the liquid crystal display device. I can say that. The liquid crystal panel and the liquid crystal display device of the present invention are particularly preferably used for large liquid crystal televisions.

It is a schematic sectional drawing of the liquid crystal panel by preferable embodiment of this invention. It is a schematic perspective view of the liquid crystal panel of FIG. 1 and Examples 1-4. 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 perspective view explaining the typical example of preferable embodiment of the phase difference element used for this invention including the relationship with the absorption axis of a polarizer. It is a schematic diagram which shows an example of the manufacturing method of retardation film used for this invention. 1 is a schematic perspective view of a liquid crystal display device according to a preferred embodiment of the present invention. It is a graph which shows the azimuth angle dependence of color shift amount ((DELTA) E) when it sees from the diagonal direction. It is a graph which shows the azimuth angle dependence of color shift amount ((DELTA) E) when it sees from the diagonal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Liquid crystal panel 10 Liquid crystal cell 11, 12 Board | substrate 13 Liquid crystal layer 21 1st polarizer 22 2nd polarizer 30 Negative C plate 40 Phase difference element 50 Isotropic optical element 60, 60 'Protective layer 70, 70' Surface Treatment layer 80 Brightness enhancement film 100 Liquid crystal panel 110 of the present invention Prism sheet 120 Light guide plate 130 Backlight 200 Liquid crystal display device 300 Feeding unit 301 Polymer film 310 Iodine aqueous solution bath 311, 312, 321, 322 Roll 320 Boric acid and iodide Aqueous solution bath containing potassium 330 Aqueous solution bath containing potassium iodide 340 Drying means 350 Polarizer 360 Winding portion 501 First feeding portion 502 Polymer film 503 Second feeding portions 504 and 506 Shrinkable film 505 Third Feeding part 507, 508 Laminate low 509 Temperature control means 510, 511, 512, 513 Roll 516 Second winding part

Claims (10)

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, the liquid crystal cell and the first polarizer A negative C plate disposed between the liquid crystal cell and the negative C plate, a retardation element disposed between the liquid crystal cell and the negative C plate, and the liquid crystal cell and the second polarizer. An isotropic optical element,
The absorption axis direction of the first polarizer is substantially perpendicular to the absorption axis direction of the second polarizer;
In the phase difference element, the refractive index ellipsoid has a relationship of nx>nz> ny, and Re [590] _Z is less than 350 nm,
The slow axis direction of the retardation element is substantially parallel to the absorption axis direction of the first polarizer.
LCD panel.   The liquid crystal panel according to claim 1, wherein the liquid crystal cell includes a liquid crystal layer including a nematic liquid crystal that is homogeneously aligned in the absence of an electric field. The liquid crystal panel according to claim 1, wherein Rth [590] _NC of the negative C plate is more than 10 nm and 200 nm or less.   The negative C plate includes a polymer film containing as a main component at least one thermoplastic resin selected from a cellulose resin, a polyamideimide resin, a polyether ether ketone resin, and a polyimide resin. 4. The liquid crystal panel according to any one of items 1 to 3.   The liquid crystal panel according to claim 1, wherein an Nz coefficient of the retardation element is less than 0.6.   The liquid crystal panel according to claim 1, wherein the retardation element includes a retardation film containing a norbornene-based resin. And Re _{[590] Z} of the phase difference element, the difference between the negative C plate of _{Rth [590] NC (Re [} 590] Z -Rth [590] NC) is a 250 to 300 nm, from claim 1 The liquid crystal panel according to any one of 6 to 6.   The said isotropic optical element contains the polymer film which has as a main component at least 1 resin chosen from acrylic resin, a cellulose resin, and a cycloolefin resin. LCD panel.   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.