JP2007206703A - Liquid crystal panel and liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal panel, provided with a liquid crystal cell of a homogeneous alignment mode having superior display characteristics, and to provide a liquid crystal display apparatus. <P>SOLUTION: The liquid crystal panel 100 includes the liquid crystal cell 10, including a liquid crystal layer containing homogeneously aligned liquid crystal molecules in the absence of an electric field; polarizers 20 and 20' arranged on both sides of the liquid crystal cell; a first optical element 30 arranged between one polarizer and the liquid crystal cell; and a second optical element 40 arranged between the other polarizer and the liquid crystal cell. The first optical element comprises a retardation film, having a refractive index profile of nx>nz>ny, satisfying Expressions (1) and (2), containing a norbornene-based resin and having an absolute value of photoelastic coefficient of 2.0×10<SP>-13</SP>to 2.0×10<SP>-11</SP>. The second optical element has 0 to 5 nm Re[590] and -5 to 5 nm Rth[590]. The first optical element has a slow axis, which is one of substantially parallel and substantially perpendicular to the absorption axis of one polarizer. Expression (1): 240 nm≤Re[590]≤350 nm and; Expression (2): 0.20≤Rth[590]/Re[590]≤0.80. <P>COPYRIGHT: (C)2007,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.

  In a liquid crystal display device having an in-plane switching (IPS) type liquid crystal cell, when no electric field is applied, liquid crystal molecules aligned in a substantially horizontal direction are rotated about 45 degrees by applying a horizontal electric field. This controls the transmission (white display) and shielding (black display). A liquid crystal display device having a conventional IPS liquid crystal cell viewed the screen from an oblique direction at an angle of 45 degrees (azimuth angles of 45 degrees, 135 degrees, 225 degrees, and 315 degrees) with respect to the absorption axis of the polarizing plate. In this case, there is a problem that the contrast ratio is lowered.

  In order to solve this problem, a λ / 2 plate showing a refractive index distribution of nx> nz> ny (however, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, It is disclosed that display characteristics in an oblique direction can be improved by using nz) (Patent Document 1). However, the disclosed technique does not sufficiently improve the contrast ratio in the oblique direction and the color shift in the oblique direction, and further improvement in display characteristics is desired.

  Conventionally, aromatic polymer films such as polycarbonate-based resins, polyarylate-based resins, and polyester-based resins have been disclosed for the λ / 2 plate showing the refractive index distribution of nx> nz> ny (Patent Literature). 2, Patent Document 3). However, since the aromatic polymer film as described above has a large photoelastic coefficient, the retardation value easily changes with respect to stress. For this reason, the phase difference value may deviate from the design value due to the contraction stress of the polarizer when exposed to high temperatures in a state of being bonded between the liquid crystal cell and the polarizer. It is a problem that display uniformity is deteriorated due to unevenness in retardation value due to unevenness in stress caused by the above.

On the other hand, an aliphatic resin film such as a norbornene resin film has a small photoelastic coefficient. However, since an aliphatic resin film hardly causes a retardation, when a retardation film showing a refractive index distribution of nx>nz> ny is to be produced, of course, at a low stretch ratio such as an aromatic polymer film. That is, a desired retardation value cannot be obtained even when stretched at a high stretch ratio. Moreover, since it extended | stretched with high draw ratio, it has been a problem that a film will fracture | rupture. Accordingly, in the prior art, a retardation film having a relationship of nx ≧ ny> nz with an aliphatic resin film having a small photoelastic coefficient has been obtained (Patent Document 4), but the relationship of nx>nz> ny is obtained. The retardation film which has is not obtained.
JP-A-11-305217 JP-A-4-305602 JP-A-5-157911 JP 2001-215332 A

  The present invention has been made to solve such a problem, and an object thereof is to provide a liquid crystal panel including a liquid crystal cell having an improved contrast ratio in an oblique direction. Another object of the present invention is to provide a liquid crystal panel and a liquid crystal display device having a liquid crystal cell having good display uniformity, which does not cause a shift or unevenness of a retardation value due to a contraction stress of a polarizer or heat of a backlight. .

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the following liquid crystal panel and liquid crystal display device, and have completed the present invention.

The liquid crystal panel of the present invention includes a liquid crystal cell, a polarizer disposed on both sides of the liquid crystal cell, a first optical element disposed between one of the polarizers and the liquid crystal cell, and the polarization A second optical element disposed between the other of the elements and the liquid crystal cell; the first optical element satisfies the following formulas (1) and (2), and a norbornene-based resin: A retardation film containing; Re [590] of the second optical element is 0 to 5 nm, and Rth [590] is −5 to 5 nm.
240 nm ≦ Re [590] ≦ 350 nm (1)
0.20 ≦ Rth [590] / Re [590] ≦ 0.80 (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  In a preferred embodiment, the slow axis of the first optical element is substantially parallel or orthogonal to the absorption axis of one of the polarizers.

  In a preferred embodiment, the liquid crystal cell includes a liquid crystal layer including liquid crystal molecules that are homogeneously aligned in the absence of an electric field. In a more preferred embodiment, the liquid crystal cell is in an IPS mode, an FFS mode, or an FLC mode.

  In a preferred embodiment, the initial alignment direction of the liquid crystal cell and the direction of the absorption axis of the polarizer on the side where the second optical element is disposed are substantially parallel.

  In a more preferred embodiment, the initial alignment direction of the liquid crystal cell and the direction of the absorption axis of the polarizer disposed on the backlight side of the liquid crystal cell are substantially parallel. In another embodiment, the initial alignment direction of the liquid crystal cell and the absorption axis direction of the polarizer disposed on the backlight side of the liquid crystal cell are substantially orthogonal to each other.

  In a preferred embodiment, the norbornene-based resin contains a ring-opening polymer and / or a ring-opening copolymer of a norbornene-based monomer.

  In a preferred embodiment, the second optical element is at least one selected from a cellulose resin, a norbornene resin, a resin containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. Contains one polymer film.

In a preferred embodiment, the second optical element is formed by laminating a negative C plate satisfying the following formulas (7) and (8) and a positive C plate satisfying the following formulas (9) and (10). Is a laminated film:
0 nm <Re [590] ≦ 10 nm (7)
20 nm <Rth [590] ≦ 400 nm (8)
0 nm <Re [590] ≦ 10 nm (9)
−400 nm ≦ Rth [590] <− 20 nm (10)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

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

In the liquid crystal panel of the present invention, the first optical element satisfying the following formulas (1) and (2) is disposed between the polarizer on one side and the liquid crystal cell, and is substantially optically isotropic. By disposing the second optical element between the polarizer on the other side and the liquid crystal cell, the contrast ratio in the oblique direction of the liquid crystal display device can be increased, and the color shift in the oblique direction can be reduced. In addition, since the first optical element in the present invention includes a retardation film containing a norbornene resin, the photoelastic coefficient can be reduced, so that the contraction stress of the polarizer and the heat of the backlight of the liquid crystal panel can be reduced. The unevenness of the phase difference value caused by the above can be prevented. Conventionally, a retardation film having a small photoelastic coefficient and a relationship of nx>nz> ny has not been obtained. On the other hand, according to the present invention, a shrinkable film having a predetermined shrinkage rate is bonded to one side or both sides of a polymer film containing a norbornene-based resin and heat-stretched, whereby the photoelastic coefficient is small and nx> ny. A retardation film having a relationship of> nz and satisfying the following formulas (1) and (2) was actually obtained. Further, Re [590] of the second optical element is 0 to 5 nm, and Rth [590] is −5 to 5 nm. As a result, good display characteristics of the liquid crystal display device can be maintained for a long time.
240 nm ≦ Re [590] ≦ 350 nm (1)
0.20 ≦ Rth [590] / Re [590] ≦ 0.80 (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

A. 1 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. FIG. 2A is a schematic perspective view when this liquid crystal panel adopts the O mode, and FIG. 2B is a schematic perspective view when this liquid crystal panel adopts the E mode. It should be noted that for the sake of easy understanding, the ratios of the vertical, horizontal, and thickness of each component in FIG. 1 and FIGS. 2A and 2B are described differently from actual ones. The liquid crystal panel 100 includes a liquid crystal cell 10, polarizers 20 and 20 ′ disposed on both sides of the liquid crystal cell 10, and one of the polarizers (the polarizer 20 in the illustrated example) and the liquid crystal cell 10. The first optical element 30 is disposed, and the second optical element 40 is disposed between the other of the polarizers (polarizer 20 ′ in the illustrated example) and the liquid crystal cell 10. Practically, any appropriate protective layer (not shown) may be disposed outside the polarizers 20 and 20 ′. In the illustrated example, the slow axis of the first optical element 30 and the absorption axis of the polarizer 20, and the slow axis (when detected) of the second optical element 40 and the absorption axis of the polarizer 20 ′ are Although the cases where they are parallel to each other are shown, they may be perpendicular to each other. The first optical element satisfies the following formulas (1) and (2) and includes a retardation film containing a norbornene resin, and the second optical element has substantially optical isotropy. In the second optical element, Re [590] is 0 to 5 nm and Rth [590] is −5 to 5 nm:
240 nm ≦ Re [590] ≦ 350 nm (1)
0.20 ≦ Rth [590] / Re [590] ≦ 0.80 (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  Preferably, the polarizer 20 ′ (that is, the polarizer on the side where the second optical element 40 is disposed) is disposed so that the absorption axis thereof is substantially parallel to the initial alignment direction of the liquid crystal cell 10. The polarizer 20 is arranged so that the absorption axis thereof is substantially orthogonal to the initial alignment direction of the liquid crystal cell 10.

  The liquid crystal panel of the present invention may be a so-called O mode or a so-called E mode. The “O-mode liquid crystal panel” refers to a liquid crystal panel in which the absorption axis of a polarizer disposed on the backlight side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are parallel to each other. The “E mode liquid crystal panel” refers to a liquid crystal panel in which the absorption axis of a polarizer disposed on the backlight side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are orthogonal to each other. In the case of an O-mode liquid crystal panel, preferably, as shown in FIG. 2A, the polarizer 20 and the first optical element 30 are arranged on the viewing side of the liquid crystal cell 10, and the second optical element 40 and the polarizer 20 ′ are It is arranged on the backlight side of the liquid crystal cell 10. In the case of an E mode liquid crystal panel, preferably, as shown in FIG. 2B, the polarizer 20 and the first optical element 30 are disposed on the backlight side of the liquid crystal cell 10, and the second optical element 40 and the polarizer 20 ′. Is arranged on the viewing side of the liquid crystal cell 10. In the present invention, the O mode as shown in FIG. This is because the O-mode arrangement can realize better optical compensation. More specifically, in the O mode arrangement, since the first optical element including the retardation film is arranged on the side far from the backlight, the liquid crystal display is hardly affected by the heat of the backlight and has little display unevenness. A device can be obtained. 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, the liquid crystal cell 10 used in the liquid crystal panel of the present invention includes a pair of substrates 11, 11 ′ and a liquid crystal layer 12 as a display medium sandwiched between the substrates 11, 11 ′. Have. One substrate (color filter substrate) 11 is provided with a color filter and a black matrix (both not shown). On the other substrate (active matrix substrate) 11 ′, a switching element (typically 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 this switching element. ) And a signal line (not shown) for supplying a source signal, and a pixel electrode and a counter electrode (both not shown) are provided. The color filter may be provided on the active matrix substrate 11 ′ side. A distance (cell gap) between the substrates 11 and 11 ′ 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, 11 ′ in contact with the liquid crystal layer 12.

  The liquid crystal layer 12 preferably includes liquid crystal molecules that are 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 (however, the refraction in the slow axis direction, the fast axis direction, and the thickness direction of the film). The rates are nx, ny, and nz, respectively). In this specification, ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same. Further, the “initial alignment direction of the liquid crystal cell” refers to a direction in which the in-plane refractive index of the liquid crystal layer that is generated as a result of alignment of liquid crystal molecules contained in the liquid crystal layer is maximized in the absence of an electric field. Typical examples of driving modes using a liquid crystal layer exhibiting such a refractive index distribution include an in-plane switching (IPS) mode, a fringe field switching (FFS) mode, and a ferroelectric liquid crystal (FLC) mode. Specific examples of the liquid crystal used in such a drive mode include nematic liquid crystal and smectic liquid crystal. For example, a nematic liquid crystal is used for the IPS mode and the FFS mode, and a smectic liquid crystal is used for the FLC 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, for example, Techno Times Publishing “Monthly Display July” p. 83-p. 88 (1997 edition) and “Liquid Crystal vol.2 No. 4” published by the Japanese Liquid Crystal Society. 303-p. 316 (1998 edition), in the normally black method, the alignment direction of the liquid crystal cell when no electric field is applied is aligned with the absorption axis of the polarizer on one side so that the upper and lower polarizing plates are If they are arranged orthogonally, the display is completely black without an electric field. When an electric field is present, the transmittance according to the rotation angle can be obtained by rotating the liquid crystal molecules while keeping them parallel to the substrate. The IPS mode includes a super-in-plane switching (S-IPS) mode and an advanced super-in-plane switching (AS-IPS) mode using a V-shaped electrode or 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 effect to generate nematic liquid crystal aligned in a homogeneous molecular arrangement in the absence of an electric field, for example, between a counter electrode and a pixel electrode formed of a transparent conductor. A device that responds with an electric field (also called a transverse electric field) parallel to the substrate. 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 interval between the counter electrode formed of a transparent conductor and the pixel electrode to be narrower than the cell gap. More specifically, SID (Society for Information Display) 2001 Digest, p. 484-p. As described in 487 and JP 2002-031812, the normally black method matches the alignment direction when no electric field is applied to the liquid crystal cell and the absorption axis of the polarizer on one side, When the upper and lower polarizing plates are arranged orthogonally, the display is completely black without an electric field. When an electric field is present, the transmittance according to the rotation angle can be obtained by rotating the liquid crystal molecules while keeping them parallel to the substrate. The FFS mode includes an advanced fringe field switching (A-FFS) mode and an ultra fringe field switching (U-FFS) mode employing a V-shaped electrode or 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 FLC mode utilizes the property that, for example, when a ferroelectric chiral smectic liquid crystal is sealed between electrode substrates having a thickness of about 1 μm to 2 μm, two stable molecular orientation states are exhibited. More specifically, the ferroelectric chiral smectic liquid crystal molecules are rotated in a plane parallel to the substrate in response to the applied voltage. In the FLC mode, black and white display can be obtained on the same principle as the IPS mode and the FFS mode. Furthermore, the FLC mode has a feature that the response speed is faster than other drive modes. In this specification, the FLC mode includes a surface stabilization (SS-FLC) mode, an antiferroelectric (AFLC) mode, a polymer stabilization (PS-FLC) mode, and a V-characteristic (V-FLC). ) Mode.

  The homogeneously aligned liquid crystal molecule refers to a liquid crystal molecule in which the alignment vector of the liquid crystal molecule is aligned in parallel and uniformly with respect to the substrate plane as a result of the interaction between the aligned substrate and the liquid crystal molecule. In the present specification, the case where the alignment vector is slightly inclined with respect to the substrate plane, that is, the case where the liquid crystal molecules have a pretilt is also included in the homogeneous alignment. When the liquid crystal molecules have a pretilt, the pretilt angle is preferably 20 ° or less from the viewpoint of maintaining a high contrast ratio and obtaining good display characteristics.

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

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

  Any appropriate cell gap may be adopted as the cell gap (substrate interval) of the liquid crystal cell depending on the purpose. The cell gap is preferably 1.0 to 7.0 μm. Within the above range, the response time can be shortened and good display characteristics can be obtained.

C. Polarizer As the polarizer used in the present invention, any appropriate polarizer can be adopted depending on the purpose. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm. The polarizers disposed on both sides of the liquid crystal cell may be the same or different.

  A polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film can be produced by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing.

  By washing the polyvinyl alcohol film with water, not only can the surface of the polyvinyl alcohol film be cleaned and the anti-blocking agent can be washed, but also the effect of preventing unevenness such as uneven dyeing can be obtained by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

D. First Optical Element Referring to FIGS. 1 and 2, the first optical element 30 is disposed between the liquid crystal cell 10 and the polarizer 20. The first optical element 30 satisfies the following formulas (1) and (2), and includes a retardation film containing a norbornene resin.
240 nm ≦ Re [590] ≦ 350 nm (1)
0.20 ≦ Rth [590] / Re [590] ≦ 0.80 (2)

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

  Re [590] of the first optical element is 240 to 350 nm, preferably 240 nm to 300 nm, more preferably 260 to 280 nm, and particularly preferably 265 nm to 275 nm. By setting Re [590] to about ½ of the measurement wavelength, the contrast ratio in the oblique direction of the liquid crystal display device can be increased.

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

  Rth [590] of the first optical element is preferably 35 to 190 nm, more preferably 90 to 190 nm, particularly preferably 100 to 165 nm, and most preferably 120 to 155 nm.

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

  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 first optical element has a relationship of nx> nz> ny.

  Rth [590] / Re [590] of the first optical element is 0.2 to 0.8, more preferably 0.2 to 0.7, and still more preferably 0.2 to 0.6. Yes, particularly preferably 0.4 to 0.6, and most preferably 0.45 to 0.55. By setting the Rth [590] / Re [590] value of the first optical element to 0.5, it is possible to achieve a characteristic in which the retardation value is substantially constant regardless of the angle, and the oblique direction of the liquid crystal display device The contrast ratio can be increased.

  The wavelength dispersion characteristic of the first optical element is preferably 1.02 to 1.30, more preferably 0.81 to 1.10, and particularly 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.

D-2. Arranging means for the first optical element As a method for arranging the first optical element 30 between the liquid crystal cell 10 and the polarizer 20, any appropriate method may be adopted depending on the purpose. Preferably, the first optical element 30 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.

  Preferably, the first optical element 30 is arranged such that its slow axis is substantially parallel or orthogonal to the absorption axis of the adjacent polarizer 20. More preferably, the first optical element 30 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. In the present specification, “substantially parallel” includes the case where the angle formed by the slow axis of the first optical element 30 and the absorption axis of the polarizer 20 is 0 ° ± 2.0 °, preferably Is 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °. “Substantially orthogonal” includes a case where the angle formed by the slow axis of the first optical element 30 and the absorption axis of the polarizer 20 is 90 ° ± 2.0 °, preferably 90 ° ± 1. 0 °, more preferably 90 ° ± 0.5 °. As the degree of deviation from these angle ranges increases, the degree of polarization of the polarizing plate decreases, and the contrast tends to decrease when used in a liquid crystal display device.

D-3. Configuration of First Optical Element The configuration (laminate structure) of the first optical element includes a retardation film containing a norbornene resin, and is particularly limited as long as it satisfies the optical characteristics described in the above section D-1. There is no. Specifically, the first optical element may be a retardation film containing a norbornene-based resin alone, or may be a laminate of two or more retardation films, and the retardation film and other films. A laminate with (preferably an isotropic film) may be used. Preferably, the first optical element is a single retardation film. This is because the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight can be reduced, and the liquid crystal panel can be thinned. When the first optical element is a laminate, an adhesive layer, a pressure-sensitive adhesive layer, or 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 first optical element can be appropriately selected depending on the number of retardation films used. For example, when the first optical element is composed of the retardation film alone, Re [590] of the retardation film is preferably equal to Re [590] of the first optical element. Therefore, it is preferable that the phase difference of the pressure-sensitive adhesive or the adhesive used when the first optical element is laminated on the polarizer or the liquid crystal cell is as small as possible. Further, for example, when the first optical element is a laminate including two or more retardation films, the total of Re [590] of each retardation film is equal to Re [590] of the first optical element. It is preferable to design to be equal. 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.

  Further, Rth [590] / Re [590] of the retardation film is preferably equal to Rth [590] / Re [590] of the first optical element regardless of the number of retardation films used. . 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 of 140 nm can be obtained by laminating so that the slow axes are parallel to each other.

  The total thickness of the first optical element is preferably 70 to 240 μm, more preferably 70 to 150 μm, and most preferably 70 to 120 μm. When the first optical element has a thickness in such a range, a liquid crystal display device excellent in optical uniformity can be obtained.

  FIG. 3 is a schematic perspective view illustrating a representative example of a preferred embodiment of the first optical element including a relationship with an absorption axis of a polarizer. 3A and 3B show the case where the first optical element 30 is a single retardation film. (A) shows the case where the slow axis of the retardation film 30 and the absorption axis of the polarizer 20 are parallel, and (b) shows that the slow axis of the retardation film 30 and the absorption axis of the polarizer 20 are orthogonal. Indicates when to do. According to such a form, the retardation film also serves as a protective layer on the liquid crystal cell side of the polarizer, which can contribute to 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. FIGS. 3C and 3D show a case where the first optical element 30 is a laminate of one retardation film 31 and one other film (preferably an isotropic film) 36. . (C) shows the case where the slow axis of the retardation film 31 and the absorption axis of the polarizer 20 are parallel, and (d) shows that the slow axis of the retardation film 31 and the absorption axis of the polarizer 20 are orthogonal. Indicates when to do. 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. FIGS. 3E and 3F show the case where the first optical element 30 is a laminate of two retardation films 31 and 32, and FIGS. 4G and 4H show the first optical element. A case where 30 is a laminate of two retardation films 31 and 32 and one other film 36 is shown. As described above, Re [590] of the retardation films 31 and 32 is designed so that the sum thereof is equal to Re [590] of the first optical element, and Rth [590] / Re [590] is , Each is designed to be equal to Rth [590] / Re [590] of the first optical element. 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.

D-4. Retardation film containing norbornene-based resin As described above, the first optical element used in the present invention includes a retardation film containing a norbornene-based 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 satisfying the above formulas (1) and (2) was actually produced using a norbornene resin. It is.

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 first optical element is preferably set to 70 to 240 μm, more preferably 70 to 150 μm. For example, when the first optical 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 first optical element). Also, for example, when the first optical element is a laminate of two retardation films, the thickness of each retardation film is arbitrary as long as the sum is a preferable overall thickness of the first optical element. A suitable thickness can be employed. Therefore, the thickness of each retardation film may be the same or different. In one embodiment in the case of laminating two retardation films, the thickness of one retardation film is preferably 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. For example, bicyclo [2.2.1] -hept-2-ene (common name: norbornene) and its derivatives can be used. Specific examples include 5-methyl-bicyclo [2.2.1] -hept-2-ene, 5,5-dimethyl-bicyclo [2.2.1] -hept-2-ene, 5-ethyl-bicyclo. [2.2.1] -Hept-2-ene, 5-propyl-bicyclo [2.2.1] -hept-2-ene, 5-butyl-bicyclo [2.2.1] -hept-2- Ene, 5-methylidene-bicyclo [2.2.1] -hept-2-ene, 5-ethylidene-bicyclo [2.2.1] -hept-2-ene, 5-vinyl-bicyclo [2.2. 1] -hept-2-ene, 5-propenyl-bicyclo [2.2.1] -hept-2-ene, 5-methoxycarbonyl-bicyclo [2.2.1] -hept-2-ene, 5- Ethoxycarbonyl-bicyclo [2.2.1] -hept-2-ene, 5-methyl- -Methoxycarbonyl-bicyclo [2.2.1] -hept-2-ene, 5-methyl-5-ethoxycarbonyl-bicyclo [2.2.1] -hept-2-ene, 5-phenyl-bicyclo [2 2.1] -hept-2-ene, 5-cyclopentyl-bicyclo [2.2.1] hept-2-ene, 5-cyclohexyl-bicyclo [2.2.1] hept-2-ene, 5-benzoyloxy-5-methylbicyclo [2.2.1] hept-2-ene, 5-trifluoromethyl-bicyclo [2.2.1] hept-2-ene, 5,6-bis ( Trifluoromethyl) -bicyclo [2.2.1] hept-2-ene,
5-benzyl-bicyclo [2.2.1] -hept-2-ene, 5-tolyl-bicyclo [2.2.1] -hept-2-ene, 5- (ethylphenyl) -bicyclo [2.2 .1] -Hept-2-ene, 5- (isopropylphenyl) -bicyclo [2.2.1] -hept-2-ene, 5-cyano-bicyclo [2.2.1] -hept-2-ene Bicyclo [2.2.1] -hept-5-enyl-2-propionate,
Bicyclo [2.2.1] -hept-5-enyl-2-methyloctanoate, bicyclo [2.2.1] -hept-5-ene-5,6-dicarboxylic dianhydride, 5-hydroxymethyl -Bicyclo [2.2.1] -hept-5-ene and polar group (for example, halogen) substituents thereof.

Also, tricyclo [4.3.1 ^2,5 . 0 ^1,6 ] -deca-3,7-diene (common name: dicyclopentadiene) and its derivatives may also be used. Specific examples include tricyclo [4.3.1 ^2,5 . 0 ^1,6 ] -dec-3-ene, 2-methyl-tricyclo [4.3.1 ^2,5 . 0 ^1,6 ] -dec-3-ene, 5-methyl-tricyclo [4.3.1 ^2,5 . 0 ^1,6 ] -dec-3-ene, and polar group (for example, halogen) substitution products thereof.

In addition, tricyclo [4.4.1 ^2,5 . 0 ^1,6 ] -undeca-3,7-diene, tricyclo [4.4.1 ^2,5 . 0 ^1,6 ] -undeca-3,8-diene, tricyclo [4.4.1 ^2,5 . 0 ^1,6 ] -undec-3-ene, and derivatives thereof (for example, polar group substituents such as halogen) can also be used.

In addition, tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene (common name: tetracyclododecene) and its derivatives may also be used. As a specific example, 8-methyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-ethyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methylidene-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-ethylidene-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-vinyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-propenyl-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, 8-ethoxycarbonyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-n-propoxycarbonyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-butoxycarbonyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-phenoxycarbonyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-trifluoromethyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methyl-8-trifluoromethyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methyl-8-methoxycarbonyl-tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methyl-8-ethoxycarbonyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methyl-8-n-propoxycarbonyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methyl-8-butoxycarbonyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene, 8-methyl-8-phenoxycarbonyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] -dodec-3-ene and the like, and substituted groups thereof (for example, halogen). 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 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 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 first optical element may contain two or more kinds 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. Specific examples include polyolefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / styrene resins, polymethyl methacrylate, polyvinyl acetate, and polyvinylidene chloride resins. General-purpose plastics such as polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, etc .; polyphenylene sulfide resins, polysulfone resins, polyethers Sulfone resin, polyether ether ketone resin, polyarylate resin, liquid crystalline resin, polyamideimide resin, polyimide resin, polytetrafluoride Super engineering plastics such as ethylene-based resins. 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.

  When the retardation film used for the first optical 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. 4 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 402 containing a norbornene-based resin is fed from the first feeding unit 401, and the adhesive roll fed from the second feeding unit 403 to both surfaces of the polymer film 402 by the laminate rolls 407 and 408. The shrinkable film 404 including the agent layer and the shrinkable film 406 including the pressure-sensitive adhesive layer fed out from the third feeding portion 405 are attached. A laminate in which a shrinkable film is attached to both surfaces of a polymer film is applied with tension in the longitudinal direction of the film by rolls 410, 411, 412 and 413 having different speed ratios while being held at a constant temperature by a heating means 409. The film is subjected to a stretching treatment while being simultaneously given a tension in the thickness direction by the shrinkable film. In the first winding part 414 and the second winding part 416, the shrinkable films 404 and 406 are peeled off from the stretched laminate together with the pressure-sensitive adhesive layer, and a retardation film (stretched film) 418 is obtained. . The obtained retardation film 418 is wound up by the third winding portion 419.

  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.

D-5. Other Films Used for the First Optical Element As the other films that can be laminated on the retardation film containing the norbornene-based resin in the first optical element 30, those having a small absolute value of the photoelastic coefficient are preferably used.

The absolute value of the photoelastic coefficient C [590] (m ² / N) of such a film is preferably 2.0 × 10 ^{−13 to} 8.0 × 10 ⁻¹¹ , more preferably 5.0 ×. 10 ^{−13 to} 2.0 × 10 ⁻¹¹ , particularly preferably 2.0 × 10 ^{−12 to} 6.0 × 10 ⁻¹² , and most preferably 2.0 × 10 ^{−12 to} 5.0 ×. ^10-12 .

  As a material for forming such a film, a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferably used. Specifically, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as diacetyl cellulose and triacetyl cellulose, acrylic resins such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymer, styrene resin, Examples thereof include acrylonitrile / styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / ethylene / styrene resins, styrene resins such as styrene / maleimide copolymers and styrene / maleic anhydride copolymers, and polycarbonate resins. Also, cycloolefin resin, norbornene resin, polyethylene resin, polyolefin resin such as polypropylene, ethylene / propylene copolymer, vinyl chloride resin, amide resin such as nylon and aromatic polyamide, aromatic polyimide, polyimide amide, etc. Imide resin, sulfone resin, polyether sulfone resin, polyether ether ketone resin, polyphenylene sulfide resin, vinyl alcohol resin, vinylidene chloride resin, vinyl butyral resin, arylate resin, polyoxymethylene resin And epoxy resins. Moreover, the polymer film which consists of a blend of the said resin, etc. are mentioned.

  Preferably, the other film is an isotropic film. In the present specification, an isotropic film refers to a film that is small enough that the retardation value does not practically affect the optical properties. If such an isotropic film having a small birefringence or a photoelastic coefficient is laminated on the retardation film containing the norbornene resin as described above, the shrinkage stress of the polarizer propagating to the retardation film, the back Since the heat of the light can be reduced, the shift and unevenness of the phase difference value can be further reduced. A retardation film containing a norbornene-based resin is unlikely to cause retardation or unevenness due to the contraction stress of the polarizer or the heat of the backlight, so that the retardation value can be shifted by using the retardation film together. In addition, a liquid crystal panel having extremely excellent display characteristics with very little unevenness can be obtained.

  Re [590] of the isotropic film is more than 0 and 5 nm or less, preferably more than 0 and 3 nm or less, particularly preferably more than 0 and 2 nm or less, and most preferably more than 0 and 1 nm or less. is there.

  Rth [590] of the isotropic film is more than 0 and 10 nm or less, preferably more than 0 and 6 nm or less, more preferably more than 0 and 4 nm or less, and most preferably more than 0 and 2 nm or less. is there.

  The thickness of the isotropic film may vary depending on the number of isotropic films and / or retardation films to be laminated. Practically, the thickness can be set so as to maintain an appropriate mechanical strength without affecting the optical characteristics of the obtained first optical element. For example, in one embodiment in the case of laminating two retardation films and one isotropic film, the thickness of the isotropic film is preferably 20 to 120 μm.

  As a specific example of the material satisfying the retardation value and the photoelastic coefficient as the isotropic film, a ring-opening (co) polymer of a norbornene monomer described in JP-A-6-511117 is required. In accordance with the above, there may be mentioned a norbornene-based resin hydrogenated after performing a polymer modification such as maleic acid addition or cyclopentadiene addition, or a polycyclic cycloolefin monomer such as norbornene described in JP-A No. 2002-348324 or Examples also include cycloolefin resins obtained by polymerizing at least one of a monocyclic cycloolefin monomer or an acyclic 1-olefin monomer in a solution state, a suspension state, a monomer melt state, or a gas phase in the presence of a metallocene catalyst.

  Also, polycarbonate resins having 9,9-bis (4-hydroxyphenyl) fluorene in the side chain described in JP-A No. 2001-253960, cellulose resins described in JP-A No. 7-112446, and the like can be mentioned. It is done. Furthermore, the polymer film described in JP-A-2001-343529, for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substituted and / or unsubstituted side chain. Resin compositions containing a thermoplastic resin having phenyl and nitrile groups are also used. Specific examples include a polymer film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer.

  In addition, NTS Publishing Co., Ltd. “Development and application technology of optical polymer materials” 2003 edition p. 194-p. A random copolymer of the monomer constituting the polymer exhibiting positive orientation birefringence described in 207 and the monomer constituting the polymer exhibiting negative orientation birefringence or an anisotropic small molecule or birefringent crystal is doped. Although a polymer etc. are mentioned, it is not limited to this.

E. Second Optical Element Referring to FIGS. 1 and 2, the second optical element 40 is disposed between the liquid crystal cell 10 and the polarizer 20 ′. The second optical element 40 is substantially optically isotropic. In this specification, “substantially optically isotropic” means that the retardation value of the optical element is small enough not to substantially affect the optical characteristics of the liquid crystal panel, and the liquid crystal cell has It means that the refractive property can be optically compensated. For example, an optical element having substantially optical isotropy includes an optical element that satisfies the following expressions (3) and (4).
0 nm ≦ Re [590] ≦ 5 nm (3)
−5 nm ≦ Rth [590] ≦ 5 nm (4)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  Re [590] of the second 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. Re [590] of the second optical element is practically 0 to 5 nm, particularly preferably 0 to 2 nm, and most preferably 0 to 1 nm as shown in the above formula (3).

  Rth [590] of the second optical element is also 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] of the second optical element is practically −5 to 5 nm, more preferably −3 to 3 nm, most preferably −2 to 2 nm as shown in the above formula (4). is there.

  A method for disposing the second optical element 40 between the liquid crystal cell 10 and the polarizer 20 ′ is not particularly limited, but an adhesive layer or a pressure-sensitive adhesive layer (not shown) is provided on both surfaces of the second optical element. It is preferable that one surface of the second optical element is bonded to one surface of the polarizer 20 ′ and the other surface is bonded to one surface of the liquid crystal cell 10. As described above, the contrast can be increased when the liquid crystal display device is used.

  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.

  It does not restrict | limit especially as an adhesive agent or an adhesive which forms the said adhesive bond layer or an 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 and other rubber-based polymers 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.

  Although the second optical element 40 is substantially optically isotropic, a slow axis may be detected in a practical range. In such a case, the second optical element 40 is preferably arranged so that its slow axis is substantially parallel or orthogonal to the absorption axis of the adjacent polarizer 20 '. Preferably, the second optical 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. In this specification, “substantially parallel” includes the case where the angle formed by the slow axis of the second optical element 40 and the absorption axis of the polarizer 20 ′ is 0 ° ± 2.0 °, The angle is preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °. “Substantially orthogonal” includes the case where the angle formed by the slow axis of the second optical element 40 and the absorption axis of the polarizer 20 ′ is 90 ° ± 2.0 °, preferably 90 ° ± 1. 0.0 °, and more preferably 90 ° ± 0.5 °. As the degree of deviation from these angular ranges increases, the degree of polarization of the polarizing plate decreases, and the contrast decreases when used in a liquid crystal display device.

  The thickness of the second optical element is within a range in which the film can maintain its self-supporting property and mechanical strength in order to reduce the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight. Thin is preferred. A typical thickness range is 20 to 500 μm, more preferably 30 to 300 μm, particularly preferably 40 to 100 μm, and most preferably 50 to 80 μm. If it is the range of such thickness, the liquid crystal panel which has favorable display uniformity can be obtained.

  The second optical element may be a single optical film or a laminate of two or more optical films. When the second optical element is a laminate, an adhesive layer, a pressure-sensitive adhesive layer, or the like for laminating the optical film may be included. As long as the second optical element has substantially optical isotropy as a whole, the optical film may be an isotropic film or a retardation film. For example, when two retardation films are laminated, each retardation film is preferably arranged so that the slow axes thereof are orthogonal to each other. By arranging in this way, the in-plane retardation value can be reduced.

  The optical film is not particularly limited as long as it satisfies the present invention, but an optical film excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like is preferably used. Examples of the material for forming the optical film include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as diacetyl cellulose and triacetyl cellulose, acrylic resins such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymer, and the like. Styrene resins, acrylonitrile / styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / ethylene / styrene resins, styrene / maleimide copolymers, styrene resins such as styrene / maleic anhydride copolymers, polycarbonate resins, etc. It is done. Also, cycloolefin resin, norbornene resin, polyethylene resin, polyolefin resin such as polypropylene, ethylene / propylene copolymer, vinyl chloride resin, amide resin such as nylon and aromatic polyamide, aromatic polyimide, polyimide amide, etc. Imide resin, sulfone resin, polyether sulfone resin, polyether ether ketone resin, polyphenylene sulfide resin, vinyl alcohol resin, vinylidene chloride resin, vinyl butyral resin, arylate resin, polyoxymethylene resin And epoxy resins. Moreover, the polymer film which consists of a blend of the said resin, etc. are mentioned.

  Moreover, as said optical film, the thing similar to the isotropic film used for the 1st optical element mentioned above is mentioned. Among them, in addition to being excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, etc., it has a low photoelastic coefficient and excellent adhesion to a polarizer, so that it can be combined with cellulose resin, norbornene resin, isobutylene. At least one polymer film selected from a resin containing an alternating copolymer made of N-methylmaleimide and an acrylonitrile / styrene copolymer is particularly preferably used.

  When the second optical element is configured by laminating a retardation film, typically, when the in-plane main refractive index is nx and ny and the refractive index in the thickness direction is nz, the refractive index distribution is Negative uniaxial retardation film satisfying nx≈ny> nz (also referred to as negative C plate) and positive uniaxial retardation film satisfying a refractive index distribution of nz> nx≈ny (also referred to as positive C plate) Are stacked so as to cancel the in-plane and thickness direction retardation values. In the present specification, nx≈ny is not limited to those strictly showing the relationship of nx = ny, and if Re [590] is 10 nm or less, it is included in the uniaxial retardation film.

  The method for laminating the negative C plate and the positive C plate is not particularly limited, but it is preferable to provide an adhesive layer or an adhesive layer between the negative C plate and the positive C plate for adhesion. The negative C plate and the positive C plate are preferably arranged so that the slow axes in the film planes are orthogonal to each other in order to cancel the in-plane retardation value.

As the second optical element, a laminated film in which a negative C plate satisfying the following formulas (7) and (8) and a positive C plate satisfying the following formulas (9) and (10) are laminated is preferably used. .
0 nm <Re [590] ≦ 10 nm (7)
20 nm <Rth [590] ≦ 400 nm (8)
0 nm <Re [590] ≦ 10 nm (9)
−400 nm ≦ Rth [590] <− 20 nm (10)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

  Re [590] of the negative C plate is preferably more than 0 and 10 nm or less, more preferably more than 0 and 3 nm or less, particularly preferably more than 0 and 2 nm or less, most preferably more than 0 and more than 1 nm. It is as follows.

  Rth [590] of the negative C plate is preferably more than 20 nm and not more than 400 nm, more preferably more than 20 nm and not more than 200 nm, and most preferably more than 20 nm and not more than 100 nm.

  The thickness of the negative C plate is preferably 20 to 500 μm, more preferably 30 to 300 μm, particularly preferably 40 to 100 μm, and most preferably 50 to 80 μm.

  Examples of the material for forming the negative C plate include any appropriate polymer film, a film obtained by curing a liquid crystalline material exhibiting a cholesteric liquid crystal phase, a film cured with a discotic liquid crystalline compound, and an inorganic layered compound.

  Specific examples of the polymer film forming the negative C plate include cellulose resins such as diacetyl cellulose and triacetyl cellulose, acrylic resins such as polymethyl methacrylate, and polycarbonate resins. Also, cycloolefin resin, norbornene resin, polyethylene resin, polyolefin resin such as polypropylene, ethylene / propylene copolymer, vinyl chloride resin, amide resin such as nylon and aromatic polyamide, aromatic polyimide, polyimide amide, etc. Imide resin, sulfone resin, polyether sulfone resin, polyether ether ketone resin, polyphenylene sulfide resin, vinyl alcohol resin, vinylidene chloride resin, vinyl butyral resin, arylate resin, polyoxymethylene resin And epoxy resins. Moreover, the polymer film which consists of a blend of the said resin, etc. are mentioned.

  The polymer film used as the negative C plate can be obtained by forming a film by a casting method, or can be obtained by stretching by any appropriate stretching method. Examples of the stretching method 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. The said extending | stretching processing method can be performed using suitable extending machines, such as a roll extending machine, a tenter, and a biaxial stretching machine, for example. Moreover, the said extending | stretching can also be performed in 2 steps or 3 steps or more. The direction in which the polymer film is stretched may be the film longitudinal direction (MD direction) or the width direction (TD direction).

  The material for forming the negative C plate is preferably a polyimide film described in JP-A No. 2003-287750 [0100] or a nematic liquid crystal monomer and a polymerizable chiral agent described in JP-A No. 2003-287623 [0123]. And a film obtained by curing a liquid crystalline material exhibiting a cholesteric liquid crystal phase. In addition, a discotic liquid crystal non-oriented layer described in JP-A-7-281028 [0068] and a water-swellable inorganic layered compound described in JP-A-9-80233 [0034] are coated on a substrate, A dry film is mentioned.

  The Re [590] of the positive C plate is preferably more than 0 and 10 nm or less, more preferably more than 0 and 3 nm or less, particularly preferably more than 0 and 2 nm or less, most preferably more than 0 and more than 1 nm. It is as follows.

  Rth [590] of the positive C plate is preferably −400 nm or more and less than −20 nm, more preferably −200 nm or more and less than −20 nm, and most preferably −100 nm or more and less than −20 nm.

  The thickness of the positive C plate is preferably 0.1 to 50 μm, more preferably 0.1 to 30 μm, particularly preferably 0.1 to 10 μm, and most preferably 0.1 to 5 μm. .

As a material for forming the positive C plate, for example, a homeotropic alignment lateral liquid crystal polymer represented by the following formula (11) described in Example 1 of JP-A-2002-174725 is formed on a substrate. A film obtained by coating and drying, a homeotropically oriented lateral liquid crystal polymer represented by the following formula (11) described in Example 1 of JP-A No. 2003-149441, and a commercially available polymerizable liquid crystal A film obtained by coating a composition containing a mixture of monomers and a polymerization initiator on a substrate together with a solvent to form a uniform vertical alignment (also referred to as homeotropic alignment) of a polymerizable liquid crystal monomer, and then curing the film. Is mentioned.

  FIGS. 5A and 5B are schematic perspective views illustrating a representative example of a preferred embodiment of the second optical element. FIG. 5A shows a case where the second optical element 40 is a single isotropic film. FIG. 5B shows a case where the second optical element 40 is a laminate of a negative C plate 41 and a positive C plate 42. The negative C plate 41 and the positive C plate 42 are arranged so that their slow axes are orthogonal to each other. Needless to say, the second optical element is not limited to the configuration of the illustrated example, and may take any appropriate configuration as long as it is substantially optically isotropic.

F. Polarizer Protective Layer The surface of the polarizer used in the liquid crystal panel of the present invention on which the first optical element and the second optical element are not bonded (that is, the polarizer 20 in FIGS. 1 and 2A and 2B). , 20 ′), a transparent film can be disposed as a protective layer for the polarizer.

  The transparent film is preferably excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like. Materials for forming the transparent film include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as diacetyl cellulose and triacetyl cellulose, acrylic resins such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymer Polymers, styrene resins, acrylonitrile / styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / ethylene / styrene resins, styrene / maleimide copolymers, styrene / maleic anhydride copolymers, styrene resins, polycarbonate resins, etc. Can be mentioned. Also, cycloolefin resin, norbornene resin, polyethylene resin, polyolefin resin such as polypropylene, ethylene / propylene copolymer, vinyl chloride resin, amide resin such as nylon and aromatic polyamide, aromatic polyimide, polyimide amide, etc. Imide resin, sulfone resin, polyether sulfone resin, polyether ether ketone resin, polyphenylene sulfide resin, vinyl alcohol resin, vinylidene chloride resin, vinyl butyral resin, arylate resin, polyoxymethylene resin And epoxy resins. Moreover, the polymer film which consists of a blend of the said resin, etc. are mentioned.

  The surface of the transparent film to which the polarizer is not adhered can be subjected to a hard coat treatment, an antireflection treatment, an antisticking treatment, or a diffusion treatment (also referred to as an antiglare treatment). The hard coat treatment is performed for the purpose of preventing the surface of the polarizing plate from being scratched. For example, a cured film excellent in hardness, slipping properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used for the transparent coating. It can be formed on the surface of the protective film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate. The sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer. The anti-glare treatment is performed for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visual recognition of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. The anti-glare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

G. Other Optical Member Next, another optical member used in combination with the liquid crystal panel of the present invention will be described. As the other optical member, any appropriate optical member applicable to the liquid crystal panel can be adopted. For example, an optical film subjected to the above hard coat treatment, antireflection treatment, antisticking treatment, or diffusion treatment (also referred to as antiglare treatment) can be used. Further, when used in combination with a commercially available brightness enhancement film (a polarized light separation film having a polarization selection layer, for example, D-BEF manufactured by Sumitomo 3M Co., Ltd.), a display device with higher display characteristics can be obtained.

H. Liquid Crystal Display Device FIG. 6 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It should be noted that, for the sake of easy understanding, the ratio of the vertical, horizontal, and thickness of each component shown in FIG. 6 is different from the actual ratio. 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, surface treatment layers 70 and 70 ′ disposed on the outer side of 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. As the brightness enhancement film 80, a polarized light separation film having a polarization selective layer (for example, “D-BEF” series, manufactured by Sumitomo 3M Limited) or the like is used. By using these optical members, a display device with higher display characteristics can be obtained. As long as the effects of the present invention can be obtained, a part of the optical member illustrated in FIG. 6 can be omitted according to the driving mode and application of the liquid crystal cell, or another optical member can be substituted.

  In one embodiment, the liquid crystal display device including the liquid crystal panel of the present invention has a contrast ratio (YW / YB) of preferably 20 or more, and more preferably in an azimuth angle 45 ° direction and a polar angle 60 ° direction. It is 30 or more, particularly preferably 50 or more, and most preferably 80 or more. In one embodiment, the maximum value of the contrast ratio in the azimuth angle 45 ° direction and polar angles 0 ° to 78 ° is preferably 400 or more, and more preferably 450 or more. In one embodiment, the minimum value of the contrast ratio in the azimuth angle 45 ° direction and the polar angles 0 ° to 78 ° is preferably 20 or more, and more preferably 50 or more. In one embodiment, the average value of the contrast ratio in the azimuth angle 45 ° direction and polar angles 0 ° to 78 ° is preferably 200 or more, and more preferably 250 or more.

  In one embodiment, a liquid crystal display device including the liquid crystal panel of the present invention has a color shift amount in an oblique direction with a contrast ratio in the above range and an azimuth angle of 45 ° and a polar angle of 60 °. (Δab value) is preferably 1 or less, more preferably 0.7 or less, particularly preferably 0.6 or less, and most preferably 0.5 or less. In one embodiment, the liquid crystal display device including the liquid crystal panel of the present invention has an oblique contrast ratio in the above range, an omnidirectional (0 ° to 360 °), and a polar angle of 60 °. The maximum value of Δxy in is preferably 0.100 or less, and more preferably 0.090 or less. Furthermore, the average value of Δxy in all directions (0 ° to 360 °) and the polar angle of 60 ° is preferably 0.060 or less.

  In the liquid crystal display device provided with the liquid crystal panel of the present invention, when a black image is displayed in a dark room at 23 ° C., the difference between the maximum luminance and the minimum luminance is preferably 1.79 or less over the entire panel surface. Preferably it is 1.58 or less.

I. Applications of the liquid crystal panel of the present invention The applications in which the liquid crystal panel and the liquid crystal display device of the present invention are used are not particularly limited, but are OA devices such as personal computer monitors, notebook computers, copiers, mobile phones, watches, digital cameras, mobile phones. Information devices (PDAs), portable devices such as portable game machines, household electrical devices such as video cameras, LCD TVs, and microwave ovens, back monitors, monitors for car navigation systems, in-vehicle devices such as car audio, and information for commercial stores It can be used for various purposes such as exhibition equipment such as a monitor for a monitor, security equipment such as a monitor for monitoring, a care monitor and a medical monitor such as a medical monitor.

  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) Identification of norbornene-based resin: ¹ H-NMR measurement was performed with the following apparatus and conditions, and the peak integration ratio of the obtained spectrum was obtained.
・ Analyzer: JEOL “JNM-EX400”
・ Observation nucleus: 1H
・ Frequency: 400 MHz
Pulse width: 45 degrees Pulse repetition time: 10 seconds Measurement temperature: room temperature (2) Molecular weight measurement method: Polystyrene was calculated as a standard sample by 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 give a 0.1% by weight solution, allowed to stand overnight, and then filtered through 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 glass transition temperature (Tg): It was determined according to JIS K7121 using the following apparatus and measuring conditions.
・ Analyzer: Differential scanning calorimeter “DSC5500” manufactured by Seiko Electronics Co., Ltd.
・ Measurement atmosphere: under nitrogen of 20 ml / min ・ Raising rate: 10 ° C./min (4) Measuring method of retardation value, wavelength dispersion characteristic, slow axis angle, light transmittance: Based on parallel Nicol rotation method Using a phase difference meter (product name “KOBRA21-ADH” manufactured by Oji Scientific Instruments), a value at a wavelength of 590 nm at 23 ° C. was measured.
(5) Photoelastic coefficient measurement method: Using a spectroscopic ellipsometer (product name “M-220” manufactured by JASCO Corporation), the retardation value of the sample is measured under stress, and the function of the stress and the retardation value It was calculated from the slope of. Specifically, an in-plane retardation value at a wavelength of 590 nm when a stress of 5 N to 15 N was applied to a 2 cm × 10 cm test piece at 23 ° C. was measured.
(6) Thickness measurement method: Measured using an Anritsu digital micrometer “K-351C type”.
(7) Measuring method of shrinkage rate of shrink film: It was determined according to the method of heating shrinkage rate A of JIS Z 1712 (however, the heating temperature was set to 140 ° C. or 160 ° C. instead of 120 ° C., and a weight of 3 g was applied to the test piece. It ’s different.) 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 circulating thermostatic chamber 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 vernier 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 S (MD) and S (TD) were calculated from: distance between standards (mm) −distance between standards after heating (mm)) / distance between standards before heating (mm)] × 100.
(8) Contrast ratio of liquid crystal display device: calculated using the following liquid crystal cell and measuring device. A white image and a black image were displayed on the liquid crystal display device, and the Y value of the XYZ display system in the azimuth angle 45 ° direction and the polar angle 60 ° direction of the display screen was measured by a product name “EZ Contrast 160D” manufactured by ELDIM. Then, the contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) in the white image and the Y value (YB) in the black image. The azimuth angle 45 ° represents an azimuth rotated 45 ° counterclockwise when the long side of the panel is 0 °.
・ Liquid crystal cell: mounted on Sony KLV-17HR2
・ Panel size: 375mm x 230mm
(9-1) Measuring method of color shift amount (Δab value) in oblique direction of liquid crystal display device: It was calculated using the following liquid crystal cell and measuring device. Specifically, a black image was displayed on the liquid crystal display device, and the hue, a value, and b value in all directions (0 ° to 360 °) in the polar angle 60 ° direction were measured. The average values of the a and b values in all directions in the polar angle 60 ° direction are a _ave. Value and b _ave. Value, respectively, and the a value and b value in the polar angle 60 ° azimuth angle 45 ° are respectively a _{45 °} value, b _{45 °} value. The color shift amount (Δab value) in the oblique direction was calculated from the following formula: {(a _{45 °} −a _ave. ) ² + (b _{45 °} −b _ave. ) ² } ^1/2 . The azimuth angle 45 ° represents an azimuth rotated 45 ° counterclockwise with the long side of the panel being 0 °.
・ Measuring device: Product name “EZ Contrast160D” manufactured by ELDIM
・ Liquid crystal cell: mounted on Sony KLV-17HR2
・ Panel size: 375mm x 230mm
(9-2) Measuring method of color shift amount (Δxy value) in oblique direction of liquid crystal display device: It was calculated using the same liquid crystal cell and measuring device as the measurement of Δab value. Specifically, a black image was displayed on the liquid crystal display device, and the hue, x value, and y value in all directions (0 ° to 360 °) in the polar angle 60 ° direction were measured. The color shift amount (Δxy value) in the oblique direction was calculated from the following formula: {(0.31-x) ² + (0.31-y) ² } ^1/2 .
(10) Evaluation method of display unevenness of liquid crystal display device: A display screen was photographed using the following liquid crystal cell and measurement device. In the table, “◯” indicates that the difference between the maximum luminance and the minimum luminance is 1.79 or less over the entire panel displaying the black image. “X” indicates that the difference between the maximum luminance and the minimum luminance is larger than 1.79 on the entire panel displaying the black image.
・ Liquid crystal cell: mounted on Sony KLV-17HR2
・ Panel size: 375mm x 230mm
・ Measuring device: Minolta 2-dimensional color distribution measuring device “CA-1500”
・ Measurement environment: Dark room (23 ℃)

[Reference Example 1]
Biaxially stretched polypropylene films having the characteristics shown in Table 1 below on both sides of a norbornene-based resin film (trade name “Zeonor ZF14-100” manufactured by Nippon Zeon Co., Ltd.) having a thickness of 100 μm (trade name “Torphan BO 2873” manufactured by Toray Industries, Inc.) (Thickness 60 μm)] was bonded through an acrylic pressure-sensitive adhesive layer (thickness 15 μm). Thereafter, the film is held in the longitudinal direction with a roll stretching machine, and stretched 1.38 times in a 146 ° C. air circulating thermostatic oven (temperature at a distance of 3 cm from the back of the film / temperature variation ± 1 ° C.). Thus, a retardation film A was produced. The properties of the obtained retardation film A are as shown in Table 2. The norbornene-based resin film had a glass transition temperature (Tg) of 136 ° C., an in-plane retardation value before stretching of 5.0 nm, and a thickness direction retardation value of 12.0 nm.

  The acrylic pressure-sensitive adhesive used in this example uses isononyl acrylate (weight average molecular weight = 550,000) synthesized by solution polymerization as a base polymer, and crosslinks a polyisocyanate compound with respect to 100 parts by weight of the polymer. A mixture of 3 parts by weight of an agent [trade name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.] and 10 parts by weight of a catalyst [trade name “OL-1” manufactured by Tokyo Fine Chemical Co., Ltd.] was used.

[Reference Example 2]
A retardation film B was produced in the same manner as in Reference Example 1 except that the stretching temperature was changed to 148 ° C. instead of 146 ° C., and the stretching ratio was changed to 1.40 times instead of 1.38 times. Table 2 shows the stretching conditions and the properties of the obtained retardation film B.

[Reference Example 3]
A retardation film C was produced in the same manner as in Reference Example 1 except that the stretching temperature was changed to 148 ° C. instead of 146 ° C., and the stretching ratio was changed to 1.35 times instead of 1.38 times. Table 2 shows the stretching conditions and the properties of the obtained retardation film C.

[Reference Example 4]
A retardation film D was produced in the same manner as in Reference Example 1 except that the stretching temperature was changed to 143 ° C. instead of 146 ° C., and the stretching ratio was changed to 1.58 times instead of 1.38 times. Table 2 shows the stretching conditions and the properties of the obtained retardation film D.

[Reference Example 5]
A retardation film E was produced in the same manner as in Reference Example 1 except that the stretching temperature was changed to 143 ° C. instead of 146 ° C., and the stretching ratio was changed to 1.52 times instead of 1.38 times. Table 2 shows the stretching conditions and the properties of the obtained retardation film E.

[Reference Example 6]
A biaxially oriented polypropylene film is formed on both sides of a polymer film (thickness 60 μm) made of a polycarbonate-based resin obtained by a conventional method using phosgene as a carbonate precursor and bisphenol A as an aromatic dihydric phenol component. It bonded together through the adhesive layer. After that, the film is held in the longitudinal direction with a roll stretching machine, and stretched 1.10 times in a 160 ° C air circulating thermostatic oven (temperature at a distance of 3 cm from the back of the film / temperature variation ± 1 ° C). A retardation film F was produced. The properties of the obtained retardation film F are as shown in Table 2. The biaxially stretched polypropylene film used in this example had a shrinkage rate at 140 ° C. of 5.7% in the MD direction and 7.6% in the TD direction. The same acrylic adhesive as in Reference Example 1 was used. The polymer film made of the polycarbonate resin had a glass transition temperature (Tg) of 150 ° C., the in-plane retardation value before stretching was 7 nm, and the retardation value in the thickness direction was 15 nm.

[Reference Example 7]
65 parts by weight of an alternating copolymer consisting of isobutylene and N-methylmaleimide (N-methylmaleimide content 50% mol, glass transition temperature 157 ° C.), acrylonitrile / styrene copolymer (acrylonitrile content 27% mol) ) 35 parts by weight and 1 part by weight of 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol (ultraviolet absorber) in the extruder The pellets were dried at 100 ° C. for 5 hours, then extruded at 270 ° C. using a 40 nmφ single-screw extruder and a 400 mm wide T-die, and the sheet-like molten resin was cooled by a cooling drum to a width of about 600 mm. A polymer film G having a thickness of 40 μm was produced. The characteristics of the polymer film G are as shown in Table 3.

[Reference Example 8]
A commercially available norbornene resin film (thickness: 40 μm) [trade name “Zeonor ZF14-040” manufactured by Nippon Zeon Co., Ltd.] was used as the polymer film H. The characteristics of the polymer film H are as shown in Table 3.

[Reference Example 9]
A solution prepared by adding 20 parts by weight of norbornene-based resin [trade name “ARTON” manufactured by JSR Corporation] to 80 parts by weight of cyclopentanone was used to prepare a 40 μm thick triacetyl cellulose film [manufactured by Fuji Photo Film Co., Ltd. The coating was applied at a thickness of 150 μm on “UZ-TAC”, Re [590] = 2.2 nm, Rth [590] = 39.8 nm], and dried at 140 ° C. for 3 minutes. After drying, the norbornene resin film formed on the surface of the TAC film was peeled off to obtain a transparent cellulose resin film, and a polymer film I was produced. Table 3 shows the characteristics of the polymer film I.

[Reference Example 10]
A polyethylene terephthalate film [Toray S-27E, thickness 75 μm] is coated with an ethyl silicate solution [Colcoat Co., Ltd.] (mixed solution of ethyl acetate and isopropyl alcohol, 2 wt%) with a gravure coater, at 130 ° C. for 30 seconds. A glassy polymer film having a thickness of 0.1 μm was formed by drying.

5 parts by weight of a homeotropic alignment side-difference type liquid crystal polymer (weight average molecular weight (Mw) = 5000) represented by the following formula (11), a commercially available polymerizable liquid crystal monomer (trade name “Palicolor LC242” manufactured by BSAF) 20 parts by weight and 1.25 parts by weight of a photopolymerization initiator (trade name “Irgacure 907” manufactured by Ciba Specialty Chemicals Co., Ltd.) were dissolved in 75 parts by weight of cyclohexanone to prepare a mixed solution. The mixed solution was coated on the glassy polymer film of the polyethylene terephthalate film as a base material using a bar coater, dried in an air-circulating constant temperature oven at 80 ° C. ± 1 ° C. for 2 minutes, and then room temperature. Then, a liquid crystal layer in which the vertical alignment state of the polymerizable liquid crystal monomer was fixed was formed on the substrate. Next, ultraviolet light (using an irradiation device using a metal halide lamp as a light source) is irradiated from the side coated with the mixed solution in an air atmosphere at 400 mJ / cm ² (measured at a wavelength of 365 nm) to cure the polymerizable liquid crystal monomer. Thus, a positive C plate was prepared on the substrate. The thickness of the obtained positive C plate was 0.55 μm, and Re [590] = 0.1 nm and Rth [590] = − 55.2 nm.

The positive C plate was peeled off from the substrate, and a commercially available 80 μm thick triacetyl cellulose film [trade name “UZ-TAC” manufactured by Fuji Photo Film Co., Ltd., Re [590] = 2.5 nm, Rth [590] = 60.2 nm] was laminated so that the slow axes were orthogonal to each other, to prepare a polymer film J. The characteristics of the polymer film J are as shown in Table 3.

[Reference Example 11]
A commercially available norbornene resin film (thickness: 100 μm) [trade name “Zeonor ZF14-100” manufactured by Nippon Zeon Co., Ltd.] was used as the polymer film K. Table 3 shows the characteristics of the polymer film K.

[Reference Example 12]
Commercially available triacetylcellulose film (thickness: 40 μm) [trade name “UZ-TAC” manufactured by Fuji Photo Film Co., Ltd. was used as the polymer film L. The characteristics of the polymer film L are as shown in Table 3.

[Reference Example 13]
A commercially available triacetyl cellulose film (thickness 80 μm) [trade name “UZ-TAC” manufactured by Fuji Photo Film Co., Ltd.] was used as the polymer film M. The characteristics of the polymer film M are as shown in Table 3.

[Example 1]
After the polyvinyl alcohol film was dyed in an aqueous solution containing iodine, it was uniaxially stretched 6 times between rolls having different speed ratios in an aqueous solution containing boric acid to obtain two polarizers P1 and P2. . The polarizer P1 and the polarizer P2 each had a moisture content of 23%, a thickness of 28 μm, a polarization degree of 99.9%, and a single transmittance of 43.5%. Next, the liquid crystal panel is taken out from the liquid crystal display device [SONY KLV-17HR2] including the liquid crystal cell in the IPS mode, the polarizing plates arranged above and below the liquid crystal cell are removed, and the glass surfaces (front and back) are cleaned. did.

  Subsequently, a retardation film A as a first optical element was laminated on the surface on the viewing side of the liquid crystal cell so that the long side of the liquid crystal cell and the slow axis of the retardation film A were parallel to each other. Next, the polarizer P1 was laminated on the surface of the retardation film A so that the slow axis of the retardation film A and the slow axis of the polarizer P1 were parallel to each other (0 ° ± 0.5 °). . Further, a commercially available triacetyl cellulose film (thickness 40 μm) [trade name “UZ-TAC” manufactured by Fuji Photo Film Co., Ltd.] was laminated on the surface of the polarizer P1 on which the retardation film A was not laminated.

  Subsequently, a polymer film G as a second optical element was laminated on the backlight side surface of the liquid crystal cell so that the short sides of the liquid crystal cell and the slow axis of the polymer film G were parallel to each other. Next, the polarizer P2 was laminated on the surface of the polymer film G so that the slow axis of the polymer film G and the slow axis of the polarizer P2 were parallel to each other (0 ° ± 0.5 °). . Further, a commercially available triacetyl cellulose film (thickness 40 μm) [trade name “UZ-TAC” manufactured by Fuji Photo Film Co., Ltd.] is laminated on the surface of the polarizer P2 on which the polymer film G is not laminated. An O-mode liquid crystal panel I having the same configuration as that shown in FIG. In the liquid crystal panel manufactured as described above, the absorption axes of the polarizer P1 and the polarizer P2 are orthogonal to each other (90 ° ± 1.0 °).

  The liquid crystal panel was incorporated into the original liquid crystal display device, the backlight was turned on, and the contrast ratio in the oblique direction was measured 10 minutes later. Table 4 shows the obtained characteristics.

  Further, the backlight was turned on for 8 hours, and then the display screen of the liquid crystal display device was photographed in a dark room using a two-dimensional color distribution measuring device “CA-1500” manufactured by Minolta Co., Ltd. As a result, as shown in FIG. 7, display unevenness due to the heat of the backlight was small.

[Example 2]
A liquid crystal panel was produced in the same manner as in Example 1 except that the retardation film B was used instead of the retardation film A as the first optical element, and the contrast ratio in the oblique direction and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

Example 3
A liquid crystal panel was produced in the same manner as in Example 1 except that the first optical element was replaced with the retardation film A and two retardation films D were laminated, and the contrast ratio and the oblique direction were oblique. The color shift amount of was measured. Table 4 shows the obtained characteristics. The two retardation films D were laminated so that their slow axes were parallel to each other.
Example 4

  A liquid crystal panel was produced in the same manner as in Example 1 except that the first optical element was replaced with the retardation film A and two retardation films E were laminated, and the contrast ratio and the oblique direction in the oblique direction were produced. The color shift amount of was measured. Table 4 shows the obtained characteristics. The two retardation films E were laminated so that their slow axes were parallel to each other.

Example 5
A liquid crystal panel was prepared in the same manner as in Example 1 except that the polymer film H was used instead of the polymer film G as the second optical element, and the contrast ratio and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

Example 6
A liquid crystal panel was produced in the same manner as in Example 1 except that the polymer film J was used instead of the polymer film G as the second optical element, and the contrast ratio and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

[Comparative Example 1]
A liquid crystal panel was produced in the same manner as in Example 1 except that the polymer film K was used instead of the polymer film G as the second optical element, and the contrast ratio in the oblique direction and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

[Comparative Example 2]
A liquid crystal panel is produced in the same manner as in Example 1 except that the second optical element is replaced with the polymer film G and two polymer films K are laminated so that their slow axes are orthogonal to each other. Then, the contrast ratio in the oblique direction was measured. Table 4 shows the obtained characteristics.

[Comparative Example 3]
A liquid crystal panel was produced in the same manner as in Example 1 except that the retardation film C was used instead of the retardation film A as the first optical element, and the contrast ratio in the oblique direction and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

[Comparative Example 4]
A liquid crystal panel was prepared in the same manner as in Example 1 except that the retardation film E was used instead of the retardation film A, and the contrast ratio in the oblique direction and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

[Comparative Example 5]
A liquid crystal panel was prepared in the same manner as in Example 1 except that the polymer film L was used instead of the polymer film G as the second optical element, and the contrast ratio in the oblique direction and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

[Comparative Example 6]
A liquid crystal panel was prepared in the same manner as in Example 1 except that the second optical element was replaced with the polymer film G and the polymer film M was used, and the contrast ratio and the color shift amount in the oblique direction were measured. did. Table 4 shows the obtained characteristics.

[Comparative Example 7]
A liquid crystal panel II was produced in the same manner as in Example 1 except that the retardation film F was used instead of the retardation film A as the first optical element. After the liquid crystal panel is incorporated in the original liquid crystal display device and the backlight is lit for 8 hours, the liquid crystal display device is used in a dark room using a two-dimensional color distribution measuring device “CA-1500” manufactured by Minolta Co., Ltd. The display screen was taken. As a result, as shown in FIG. 8, display unevenness due to the heat of the backlight was very large.

[Example 7]
On both sides of a polymer film containing a hydrogenated ring-opening polymer of a norbornene monomer having a thickness of 130 μm [trade name “ARTON FLZU130D0” manufactured by JSR], a shrinkable film [trade name “Torphan BO 2873” manufactured by Toray Industries, Inc.] And bonded together through an acrylic pressure-sensitive adhesive layer. Then, the film longitudinal direction was hold | maintained with the roll extending | stretching machine, and it extended | stretched 1.42 times in 146 degreeC air circulation type thermostat oven, and obtained retardation film N with a thickness of 143 micrometers. The optical properties of this retardation film N are as follows: Re [590] = 269 nm, Rth [590] = 137 nm, Nz = 0.51, Re [480] / Re [590] = 1.0, absolute value of photoelastic coefficient = 5.10 × 10 ⁻¹² . The properties of the shrinkable film are as shown in Table 1 above.

  Next, a liquid crystal panel including an IPS mode liquid crystal cell [ELG Electronics Japan Co., Ltd. wide 23-inch liquid crystal television product name “FLATRON CRL-23WA”] is taken out and placed above and below the liquid crystal cell. The polarizing plate was removed and the glass surface (front and back) was washed.

  Subsequently, a retardation film N as a first optical element was laminated on the viewing side surface of the liquid crystal cell so that the long side of the liquid crystal cell and the slow axis of the retardation film N were orthogonal to each other. Next, a polarizer P1 was laminated on the surface of the retardation film N so that the long side of the liquid crystal cell and the absorption axis of the polarizer P1 were parallel to each other. At this time, the slow axis of the retardation film N and the absorption axis of the polarizer P1 are orthogonal to each other (90 ° ± 0.5 °). Further, a commercially available triacetyl cellulose film (thickness 40 μm) [trade name “UZ-TAC” manufactured by Fuji Photo Film Co., Ltd.] was laminated on the surface of the polarizer P1 on which the retardation film N was not laminated.

  Subsequently, a polymer film G as a second optical element was arranged on the backlight side surface of the liquid crystal cell so that the long side of the liquid crystal cell and the slow axis of the polymer film G were orthogonal to each other. Next, the polarizer P2 was arranged on the surface of the polymer film G so that the long side of the liquid crystal cell and the absorption axis of the polarizer P2 were orthogonal to each other. At this time, the slow axis of the polymer film G and the absorption axis of the polarizer P2 are parallel to each other (0 ° ± 0.5 °). Furthermore, on the surface of the polarizer P2 on which the polymer film G is not laminated, a commercially available triacetyl cellulose film (thickness 40 μm) [Fuji Photo Film Co., Ltd., trade name “UZ-TAC”] is laminated, and O A mode liquid crystal panel III was produced. In the liquid crystal panel III thus produced, the absorption axes of the polarizer P1 and the polarizer P2 are orthogonal to each other (90 ° ± 1.0 °), and the absorption axis of the polarizer P2 and the liquid crystal cell The initial alignment directions are parallel to each other (0 ° ± 0.5 °).

The liquid crystal panel III is incorporated in the original liquid crystal display device, the backlight is turned on, and after 10 minutes, all directions (azimuth angle 0 ° to 360 °), polar angle 0 ° (panel normal direction) to 78 ° The contrast ratio and Δxy value were measured. Note that the larger the contrast ratio, the better the display characteristics. The Δxy value is a value calculated by Δxy = {(0.31-x) ² + (0.31-y) ² } ^1/2 , and indicates a coloring amount from pure black. This Δxy value is one of indices indicating the color shift amount of the liquid crystal display device, and the smaller the value, the better the display characteristics. FIG. 9 is a contrast contour map of the liquid crystal panel III. The maximum value of the contrast ratio in the azimuth angle 45 ° direction and polar angles 0 ° to 78 ° of the liquid crystal panel III was 460, the minimum value was 79.1, and the average value was 280.6. Moreover, the maximum value of Δxy value in all directions (azimuth angle 0 ° to 360 °) and polar angle 60 ° direction was 0.085, the minimum value was 0.013, and the average value was 0.057. .

[Comparative Example 8]
A liquid crystal panel IV was produced in the same manner as in Example 7 except that the first optical element was not used. This liquid crystal panel IV is incorporated into the original liquid crystal display device, the backlight is turned on, and after 10 minutes, all directions (azimuth angle 0 ° to 360 °), polar angle 0 ° (panel normal direction) to 78 ° The contrast ratio and Δxy value were measured. FIG. 10 is a contrast contour map of the liquid crystal panel IV. The maximum value of the contrast ratio in the azimuth angle 45 ° direction and polar angles 0 ° to 78 ° of the liquid crystal panel IV was 381, the minimum value was 11.4, and the average value was 154.7. In addition, the maximum value of Δxy value in all directions (azimuth angle 0 ° to 360 °) and polar angle 60 ° directions was 0.14, the minimum value was 0.012, and the average value was 0.068. .

  Further, the contrast ratio of the liquid crystal panel III and the liquid crystal panel IV was compared at an azimuth angle of 45 ° and a polar angle of 0 ° (panel normal direction) to 78 °. The result is shown in FIG. Furthermore, for the liquid crystal panel III and the liquid crystal panel IV, Δxy values in all directions at a polar angle of 60 ° were compared. The result is shown in FIG.

[Evaluation]
As shown in Examples 1 to 4, when the retardation value of the second optical element is small, the liquid crystal having a high contrast ratio in the oblique direction when the Re [590] value of the first optical element is in the range of 240 to 350 nm. A display device was obtained. Further, as shown in Examples 5 to 6, when the Re [590] value of the second optical element is 0 to 5 nm and the Rth [590] value is in the range of −5 to 5 nm, the contrast ratio in the oblique direction A liquid crystal display device having a high value was obtained. In the liquid crystal display device including the liquid crystal panel of Example 1, display unevenness due to the heat of the backlight was very small even when the backlight was lit for a long time. Also, the liquid crystal display devices of Examples 2 to 6 had very small display unevenness as in Example 1. However, in Comparative Examples 2 to 6, since the phase difference value of the first optical element or the second optical element is outside the above range, only a liquid crystal display device having a low contrast ratio in the oblique direction can be obtained. Moreover, since the liquid crystal display device provided with the liquid crystal panel using the retardation film obtained by the conventional technique shown in Comparative Example 5 uses the retardation film having a large photoelastic coefficient obtained by the conventional technique, The display unevenness due to heat was very large.

  As is clear from FIGS. 11 and 12, the liquid crystal display device including the liquid crystal panel III obtained in Example 7 has a high contrast ratio in all directions, and both the maximum value and the average value of the color shift amount are small. Excellent display characteristics were obtained. On the other hand, the liquid crystal display device including the liquid crystal panel IV obtained in Comparative Example 8 can obtain only display characteristics in which the contrast ratio is low in all directions and the maximum value and average value of the color shift amount are both large. It was.

  As described above, according to the liquid crystal panel of the present invention, the contrast ratio in the oblique direction can be increased and the color shift amount in the oblique direction can be reduced. Therefore, the liquid crystal panel is extremely useful for improving the display characteristics of the liquid crystal display characteristics. It can be said. The liquid crystal panel of the present invention can be suitably used for a liquid crystal display device and a liquid crystal television.

It is a schematic sectional drawing of the liquid crystal panel by preferable embodiment of this invention. It is a schematic perspective view of the liquid crystal panel of FIG. It is a schematic perspective view explaining the typical example of preferable embodiment of the 1st optical element used for this invention including the relationship with the absorption axis of a polarizer. It is a schematic diagram which shows the concept of the typical manufacturing process of the phase difference film used for this invention. It is a schematic perspective view explaining the typical example of preferable embodiment of the 2nd optical element used for this invention. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It is a photograph which shows the measurement result of the display nonuniformity of the liquid crystal cell by the Example of this invention. It is a photograph which shows the measurement result of the display nonuniformity of the liquid crystal cell by a comparative example. It is a contrast contour map of the liquid crystal panel by the Example of this invention. It is a contrast contour map of the liquid crystal panel of a comparative example. It is a graph which compares and shows contrast ratio about the liquid crystal panel of an Example and a comparative example. It is a graph which compares and shows the amount of color shift about the liquid crystal panel of an Example and a comparative example.

Explanation of symbols

100: Liquid crystal panel 10: Liquid crystal cell 20, 20 ′: Polarizer 30: First optical element 31, 32: Retardation film 36: Isotropic film 40: Second optical element 41: Negative C plate 42: Positive C plate

Claims (5)

A liquid crystal cell comprising a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field, a polarizer disposed on both sides of the liquid crystal cell, and between one of the polarizers and the liquid crystal cell A first optical element disposed, and a second optical element disposed between the other of the polarizers and the liquid crystal cell,
The first optical element has a refractive index distribution of nx>nz> ny, satisfies the following formulas (1) and (2), contains a norbornene-based resin, and has an absolute value of a photoelastic coefficient of 2 A retardation film which is 0.0 × 10 ^{−13 to} 2.0 × 10 ⁻¹¹ ,
Re [590] of the second optical element is 0 to 5 nm, Rth [590] is −5 to 5 nm,
A liquid crystal panel in which the slow axis of the first optical element is substantially parallel or orthogonal to the absorption axis of one of the polarizers:
240 nm ≦ Re [590] ≦ 350 nm (1)
0.20 ≦ Rth [590] / Re [590] ≦ 0.80 (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.   The liquid crystal panel according to claim 1, wherein the liquid crystal cell is in an IPS mode, an FFS mode, or an FLC mode.   The liquid crystal panel according to claim 1, wherein the norbornene-based resin contains a ring-opening polymer and / or a ring-opening copolymer of a norbornene-based monomer.   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.