CN100407001C - Liquid crystal panel and liquid crystal display device - Google Patents

Abstract

The present invention provides a liquid crystal panel having improved oblique contrast and good display uniformity without shifting or unevenness of retardation values due to shrinkage stress of polarizers or heat of backlight. A liquid crystal panel according to an embodiment of the present invention includes a liquid crystal unit, polarizers arranged on both sides of the liquid crystal unit, a first optical element arranged between one polarizer and the liquid crystal unit, and a first optical element arranged between the other polarizer and the liquid crystal unit. The second optical element, wherein the first optical element includes a retardation film containing a styrene-based resin and a polycarbonate-based resin and satisfies the following expressions (1) and (2), and the second optical element substantially has an optical isotropy Isotropic: 240nm≤Re[590]≤350nm...(1); 0.20≤Rth[590]/Re[590]≤0.80...(2).

Description

Liquid crystal panel and liquid crystal display device

technical field

The invention relates to a liquid crystal panel with a liquid crystal unit, a polarizer and an optical element. Furthermore, the present invention relates to a liquid crystal television and a liquid crystal display device both using the liquid crystal panel.

Background technique

A liquid crystal display device equipped with an in-plane switching (IPS) mode liquid crystal cell includes adjusting the light transmittance ( white display) and light shielding (black display) are controlled. A problem with a conventional liquid crystal display device equipped with an IPS mode liquid crystal cell is that the contrast ratio of the screen viewed from an oblique direction (45°, 135°, 225° or 315° in azimuth) at an angle of 45° to the absorption axis of the polarizer will deteriorate. worse.

In order to solve this problem, a method comprising using a refractive index distribution of nx>ny>nz (wherein, nx, ny and nz respectively represent the refractive index of the slow axis direction, fast axis direction and thickness direction of the film) of λ/2 panel to improve oblique display performance (for example, JP 11-305217A). However, the disclosed technology does not provide sufficient improvement in oblique contrast ratio and oblique color shift, so further improvement in display performance is required.

Heretofore, aromatic polymer films such as polycarbonate-based resins, polyarylate-based resins, or polyester-based resins have been used as λ/2 plates with a refractive index distribution of nx>ny>nz (for example, JP 04 -305602A or JP 05-157911A). However, the photoelastic coefficient of the aromatic polymer film is large, and its retardation value may be easily changed by stress. Therefore, the aromatic polymer film has a problem in that the display uniformity is lowered as described below. In the case where the aromatic polymer film attached between the liquid crystal cell and the polarizer is exposed to high temperature, the retardation value may deviate from the design value due to shrinkage stress. In addition, non-uniform stress due to heat of the backlight may cause non-uniform phase difference values.

Meanwhile, an aliphatic resin film such as a norbornene-based resin film has a small photoelastic coefficient. However, an aliphatic resin film hardly causes retardation, and a desired retardation value cannot be obtained by stretching at a low draw ratio, or even at a high draw ratio, as in an aromatic polymer film. Stretching at high draw ratios creates a problem of film breakage. In recent years, along with the increase in screen size and the increase in the brightness of backlights, further improvements in the display uniformity of liquid crystal panels are required. However, the conventional technology as described above cannot provide a liquid crystal panel that sufficiently satisfies these demands.

Contents of the invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal panel having a liquid crystal cell with improved oblique contrast. Another object of the present invention is to provide a liquid crystal panel and a liquid crystal display device, both of which have good display uniformity and will not cause shifts or unevenness in phase difference values due to shrinkage stress of polarizers or heat of backlight. LCD unit.

In order to solve the above-mentioned problems, the inventors of the present invention conducted intensive studies and found that the above-mentioned object can be achieved by the following liquid crystal panel and liquid crystal display device, thereby completing the present invention.

A liquid crystal panel according to an embodiment of the present invention includes a liquid crystal unit, polarizers disposed on both sides of the liquid crystal unit, a first optical element disposed between one polarizer and the liquid crystal unit, and a first optical element disposed between the other polarizer and the liquid crystal unit The second optical element, wherein the first optical element includes a retardation film containing a styrene-based resin and a polycarbonate-based resin and satisfies the following expressions (1) and (2), and the second optical element basically has optical Homotropic:

240nm≤Re[590]≤350nm …(1)

0.20≤Rth[590]/Re[590]≤0.80 …(2)

In one embodiment of the present invention, the slow axis of the first optical element is substantially parallel to the absorption axis of one polarizer and substantially perpendicular to the absorption axis of the other polarizer.

In another embodiment of the present invention, a liquid crystal cell comprises a liquid crystal layer comprising nematic liquid crystals that are homogeneously aligned in the absence of an electric field.

In another embodiment of the present invention, the refractive index distribution of the liquid crystal layer is nx>ny=nz.

In another embodiment of the present invention, the liquid crystal cell includes one of an IPS mode and an FFS mode.

In another embodiment of the present invention, the initial alignment direction of the liquid crystal cell is substantially parallel to the absorption axis direction of the polarizer disposed on the side of the second optical element.

In another embodiment of the present invention, the initial alignment direction of the liquid crystal cell is substantially parallel to the absorption axis direction of the polarizer disposed on the backlight side of the liquid crystal cell.

In another embodiment of the present invention, the initial alignment direction of the liquid crystal cell is substantially perpendicular to the direction of the absorption axis of the polarizer disposed on the backlight side of the liquid crystal cell.

In another embodiment of the present invention, the wavelength dispersion of the first optical element is 0.81 to 1.10.

In another embodiment of the present invention, the first optical element includes a single-layer retardation film including a styrene-based resin and a polycarbonate-based resin.

In another embodiment of the present invention, the first optical element includes a laminate including a retardation film including a styrene-based resin and a polycarbonate-based resin.

In another embodiment of the present invention, when the total solid content is taken as 100 parts by weight, the content of the styrene-based resin in the retardation film is 10 to 40 parts by weight.

In another embodiment of the present invention, the polycarbonate-based resin in the retardation film contains repeating units represented by formulas (5) and (6).

In another embodiment of the present invention, the absolute value of the photoelastic coefficient of the retardation film is 2.0×10 ⁻¹¹ to 8.0×10 ⁻¹¹ m ² /N measured at 23° C. using light having a wavelength of 590 nm.

In another embodiment of the present invention, the second optical element satisfies the following expressions (3) and (4):

0nm≤Re[590]≤10nm ...(3)

0nm≤Rth[590]≤20nm ... (4).

In another embodiment of the present invention, the second optical element comprises at least one type selected from cellulose-based resins, norbornene-based resins, alternating copolymers containing isobutylene and N-methylmaleimide, and acrylonitrile /Polymer film of styrene copolymer.

In another embodiment of the present invention, the second optical element comprises layering a cathode C-plate satisfying the following expressions (7) and (8) and an anode C-plate satisfying the following expressions (9) and (10). The laminated film prepared by stacking:

0nm≤Re[590]≤10nm …(7)

20nm≤Rth[590]≤400nm ...(8)

0nm≤Re[590]≤10nm …(9)

-400nm≤Rth[590]≤-20nm...(10).

In another embodiment of the present invention, the liquid crystal panel further includes a protective film on the outside of each polarizer.

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

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

The liquid crystal panel provided by the present invention is equipped with the first optical element which satisfies the following expressions (1) and (2) and is arranged between one polarizer and the liquid crystal unit and has substantially optical isotropy and is arranged on the other The second optical element between the polarizer and the liquid crystal unit increases the oblique contrast of the liquid crystal display device. The photoelastic coefficient of the first optical element of the present invention comprising a retardation film containing a styrene-based resin and a polycarbonate-based resin is small, thereby preventing a retardation due to shrinkage stress of a polarizer of a liquid crystal panel or heat of a backlight Uneven value. A retardation film having a small photoelastic coefficient and having a relationship of nx>nz>ny has not been obtained so far. However, in the present invention, a shrinkable film having a predetermined shrinkage ratio is attached to one or both sides of a polymer film containing a styrene-based resin and a polycarbonate-based resin, and the resulting product is thermally stretched, thereby There is provided a retardation film satisfying the following expressions (1) and (2) having a small photoelastic coefficient and having a relationship of nx>nz>ny. Therefore, good display performance of the liquid crystal display device can be maintained for a long time.

240nm≤Re[590]≤350nm …(1)

0.20≤Rth[590]/Re[590]≤0.80 ...(2)

(In expressions (1) and (2), Re[590] and Rth[590] represent the in-plane retardation value and the retardation value in the thickness direction of the film measured at 23°C using light with a wavelength of 590nm .)

Description of drawings

In the attached picture:

1 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention;

2A is a schematic perspective view of the liquid crystal panel shown in FIG. 1, and FIG. 2B is a schematic perspective view of a liquid crystal panel according to another preferred embodiment of the present invention;

3A to 3H are each a schematic perspective view illustrating a typical preferred embodiment of the first optical element used in the present invention, including its relationship to the absorption axis of the polarizer;

4 is a schematic diagram showing the concept of a typical preparation method of a retardation film used in the present invention;

5A and 5B are each a schematic perspective view illustrating an exemplary preferred embodiment of a second optical element used in the present invention;

6 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention;

7 is a photograph showing the results of measurement of display non-uniformity of a liquid crystal cell according to Example 1 of the present invention; and

FIG. 8 is a photograph showing the measurement results of display non-uniformity of a liquid crystal cell according to Comparative Example 5. FIG.

Detailed ways

A. Outline of the entire LCD panel

FIG. 1 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. FIG. 2A is a schematic perspective view of an O-mode liquid crystal panel, and FIG. 2B is a perspective schematic view of an E-mode liquid crystal panel. Note that, for the sake of clarity, the ratios of the length, width and height of each member in FIGS. 1 , 2A and 2B are different from the actual members. The liquid crystal panel 100 is equipped with a liquid crystal unit 10, polarizers 20 and 20′ arranged on both sides of the liquid crystal unit 10, a second polarizer arranged between a polarizer (the polarizer 20 in FIGS. 1, 2A and 2B) and the liquid crystal unit 10. An optical element 30 and a second optical element 40 disposed between another polarizer (polarizer 20 ′ in FIGS. 1 , 2A and 2B ) and the liquid crystal cell 10 . In practical applications, any suitable protective film (not shown) may be arranged on the outside of the polarizers 20 and 20'. 1, 2A and 2B all show the slow axis of the first optical element 30 and the absorption axis of the polarizer 20 parallel to each other and the slow axis of the second optical element 40 (in detection) and the absorption axis of the polarizer 20' parallel to each other. Condition. However, the slow axis of the first optical element 30 and the absorption axis of the polarizer 20 may be perpendicular to each other, and the slow axis of the second optical element 40 (during detection) and the absorption axis of the polarizer 20' may be perpendicular to each other. The first optical element includes a retardation film containing a styrene-based resin and a polycarbonate-based resin and satisfying the following expressions (1) and (2), while the second optical element has substantially optical isotropy.

240nm≤Re[590]≤350nm …(1)

0.20≤Rth[590]/Re[590]≤0.80 ...(2)

(In expressions (1) and (2), Re[590] and Rth[590] represent the in-plane retardation value and the retardation value in the thickness direction of the film measured at 23°C using light with a wavelength of 590nm .

The polarizer 20' is preferably configured such that its absorption axis is substantially parallel to the initial alignment direction of the liquid crystal cell 10. The polarizer 20 is preferably configured such that its absorption axis is substantially perpendicular to the initial alignment direction of the liquid crystal cell 10 .

The liquid crystal panel of the present invention may be so-called O-mode or so-called E-mode. The term "O-mode liquid crystal panel" refers to a liquid crystal panel in which an absorption axis of a polarizer disposed on the backlight side of a liquid crystal cell and an initial alignment direction of a liquid crystal cell are parallel to each other. The term "E-mode liquid crystal panel" refers to a liquid crystal panel in which an absorption axis of a polarizer arranged on the backlight side of a liquid crystal cell and an initial alignment direction of a liquid crystal cell are perpendicular to each other. As shown in FIG. 2A, in an O-mode liquid crystal panel, the polarizer 20 and the first optical element 30 are preferably disposed on the viewing side of the liquid crystal cell 10, while the second optical element 40 and the polarizer 20' are preferably disposed on the liquid crystal cell. 10's backlit side. As shown in FIG. 2B, in an E-mode liquid crystal panel, the polarizer 20 and the first optical element 30 are preferably disposed on the backlight side of the liquid crystal panel 10, while the second optical element 40 and the polarizer 20' are preferably disposed on the liquid crystal cell. 10's viewing side. In the present invention, an O-mode liquid crystal panel as shown in FIG. 2A is preferred because the O-mode configuration can achieve better optical compensation. Specifically, in the configuration of the O-mode, the first optical element including the retardation film is arranged on the side away from the backlight, and thus is hardly affected by the heat of the backlight, thereby providing almost no There are liquid crystal display devices with display unevenness. Hereinafter, a specific description will be given of components of the liquid crystal panel according to the present invention.

B. LCD unit

Referring to FIG. 1, a liquid crystal cell 10 used in a liquid crystal panel of the present invention is provided with a pair of substrates 11 and 11 and a liquid crystal layer 12 disposed between the substrates 11 and 11' as a display medium. One substrate (color filter substrate) 11 is provided with color filters and a black matrix (both not shown). The other substrate (active matrix substrate) 11' is equipped with switching elements (usually TFT, not shown) for controlling the electro-optical properties of liquid crystals, scanning lines (not shown) for providing gate signals to the switching elements, and for providing A signal line (not shown) for a source signal and a pixel electrode and a counter electrode (both not shown). Color filters can also be configured in the active matrix substrate 11'. The distance (cell gap) between the substrates 11 and 11' is controlled by spacers (not shown). An alignment film (not shown) formed of, for example, polyimide is disposed on a side of each of the substrates 11 and 11 ′ that is in contact with the liquid crystal layer 12 .

Preferably, the liquid crystal layer 12 contains nematic liquid crystals that are uniformly aligned in the absence of an electric field. The refractive index profile of the liquid crystal layer (finally a liquid crystal cell) is usually nx>ny=nz (where nx, ny and nz represent the refractive index of the film in the slow axis direction, fast axis direction and thickness direction, respectively). In the description of the present invention, ny=nz includes not only the case where ny and nz are completely equal, but also the case where ny and nz are substantially equal. In addition, the phrase "the initial alignment direction of the liquid crystal cell" refers to the direction in which the alignment of the nematic liquid crystal in the liquid crystal layer provides the maximum in-plane refractive index of the liquid crystal layer in the absence of an electric field. Typical examples of driving modes using a liquid crystal layer showing such a refractive index distribution include an in-plane switching (IPS) mode and a fringe field switching (FFS) mode.

In the IPS mode, nematic liquid crystals uniformly aligned in the absence of an electric field, for example, by using an electric field parallel to the substrate generated between a counter electrode and a pixel electrode each formed of a metal by using the electrically controlled birefringence (ECB) effect ( Also known as the horizontal electric field) to respond. Specifically, such as "Monthly Display July (Monthly Display July)" (pp. 83 to 88, published by Techno Times, 1997) or "Ekisho (LCD) vol.2, No.4" (pp. 303 to 316 page, Japanese Liquid Crystal Society (Japanese Liquid Crystal Society (Japanese Liquid Crystal Society) publication, 1998), the normal black mode provides a complete black display in the absence of an electric field by: changing the alignment direction of the liquid crystal cell without an applied electric field The absorption axis of one polarizer is in the same direction and the polarizers are vertically arranged above and below the liquid crystal cell. In the case of applying an electric field, the liquid crystal molecules rotate while remaining parallel to the substrate, thereby obtaining transmittance according to the rotation angle. The IPS mode includes a super in-plane switching (S-IPS) mode using a V-shaped electrode, a Z-shaped electrode, etc., and an advanced super in-plane switching (AS-IPS) mode. Examples of commercially available IPS mode liquid crystal display devices include a 20-inch wide liquid crystal TV "Wooo" (trade name, manufactured by Hitachi, Ltd. (Hitachi Corporation)), a 19-inch liquid crystal display "ProLite E481S-1" (trade name, Iiyama Corporation (Iiyama Corporation)) and 17-inch TFT liquid crystal display "FlexScan L565" (trade name, Eizo Nanao Corporation (Eizo Corporation)).

In the FFS mode, uniformly aligned nematic liquid crystals in the absence of an electric field, for example by using the electrically controlled birefringence (ECB) effect, are generated between the counter electrode and the pixel electrode each formed of a transparent conductor parallel to the counter electrode The electric field of the substrate (also known as the horizontal electric field) responds. The horizontal electric field in such an FFS mode is also called a fringe electric field, which can be generated by setting the distance between the counter electrode and the pixel electrode each formed of a transparent conductor to be narrower than the cell gap. Specifically, as described in "Society for Information Display (SID) (Society for International Information Display) 2001 Digest" (pp. 484 to 487) or JP2002-031812A, the normal black mode in the absence of an electric field by Provide a complete black display: make the alignment direction of the liquid crystal cell and the absorption axis of a polarizer in the same direction without applying an electric field and make the polarizers vertically arranged above and below the liquid crystal cell. In the case of applying an electric field, the liquid crystal molecules rotate while remaining parallel to the substrate, thereby obtaining transmittance according to the rotation angle. The FFS mode includes an Advanced Fringe Field Switching (A-FFS) mode or an Ultra Fringe Field Switching (U-FFS) mode using a V-shaped electrode, a Z-shaped electrode, or the like. Examples of commercially available FFS mode liquid crystal display devices include Tablet PC "M1400" (trade name, manufactured by Motion Computing Corporation).

Uniformly aligned nematic liquid crystal molecules are obtained through the interaction between the aligned substrate and the nematic liquid crystal molecules, wherein the alignment vectors of the nematic liquid crystal molecules are parallel to the plane of the substrate and uniformly aligned. In the specification of the present invention, uniform alignment includes the case where the alignment vector is slightly inclined with respect to the substrate surface, that is, the case where the nematic liquid crystal molecules are pre-tilted. In the case of pretilt of the nematic liquid crystal, it is preferable that the pretilt angle is 20° or less in order to maintain a large contrast ratio and obtain good display performance.

Any appropriate nematic liquid crystal can be used as the nematic liquid crystal according to purposes. Nematic liquid crystals may have positive dielectric anisotropy or negative dielectric anisotropy. Specific examples of nematic liquid crystals having positive dielectric anisotropy include "ZLI-4535" (trade name, manufactured by Merck Corporation, Japan). Specific examples of nematic liquid crystals having negative dielectric anisotropy include "ZLI-2806" (trade name, manufactured by Merck Corporation, Japan). The difference between the ordinary refractive index (no) and the extraordinary refractive index (ne), that is, the birefringence (Δn _LC ) may be appropriately set according to the response rate, transmittance, etc. of the liquid crystal. Usually, however, a birefringence of 0.05 to 0.30 is preferred.

As the cell gap (distance between substrates) of the liquid crystal cell, any appropriate cell gap can be used according to purposes. However, it is preferable that the cell gap is 1.0 to 7.0 μm. A cell gap within the above range can reduce response time and provide good display performance.

C. Polarizer

Any suitable polarizer can be used as the polarizer used in the present invention according to the purpose. Examples thereof include adsorption of, for example, iodine or a dichroic dye on a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or a partially saponified ethylene/vinyl acetate copolymer-based film. A dichroic substance and a polyene-based oriented film such as a dehydrated product of a polyvinyl alcohol-based film or a dechlorinated product of a polyvinyl chloride-based film prepared by uniaxially stretching the film. Among them, a film prepared by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol-based film and uniaxially stretching the film is particularly preferable because of its high polarization dichroism. The thickness of the polarizer is not particularly limited, but is usually 5 to 80 μm. The polarizers arranged on both sides of the liquid crystal cell may be the same or different from each other.

A polarizer prepared by adsorbing iodine on a polyvinyl alcohol-based film and uniaxially stretching the film can be produced, for example, by dipping a polyvinyl alcohol-based film in an aqueous solution of iodine to dye it, and then The film is stretched to a length of 3 to 7 times the original length. The aqueous solution may contain boric acid, zinc sulfate, zinc chloride, or the like as necessary, or the polyvinyl alcohol-based film may be immersed in an aqueous solution of potassium iodide or the like. In addition, before dyeing, this polyvinyl alcohol film can be immersed in water and washed as needed.

Washing the polyvinyl alcohol-based film with water not only removes contaminants on the surface of the film or washes off the release agent, but also provides an effect of preventing unevenness (such as uneven dyeing caused by swelling of the polyvinyl alcohol-based film), such as Uneven dyeing caused by swelling of polyvinyl alcohol-based films. Stretching of the film may be performed before, after or simultaneously with iodine dyeing of the film. Stretching can be performed in an aqueous solution of boric acid or potassium iodide, or in a water bath.

D. First Optical Element

Referring to FIGS. 1 , 2A and 2B , the first optical element 30 is disposed between the liquid crystal cell 10 and the polarizer 20 . The first optical element 30 includes a retardation film containing a styrene-based resin and a polycarbonate-based resin and satisfying the following expressions (1) and (2).

240nm≤Re[590]≤350nm …(1)

0.20≤Rth[590]/Re[590]≤0.80…(2)

D-1. Optical properties of the first optical element

In the specification of the present invention, Re[590] refers to an in-plane retardation value measured by light having a wavelength of 590 nm at 23°C. Re[590] can be determined from the equation Re[590]=(nx-ny)×d (wherein, nx and ny represent the refractive index of film slow axis direction and fast axis direction under the wavelength of 590nm respectively, and d(nm ) represents the thickness of the film). Note that the slow axis refers to the direction that provides the maximum in-plane refractive index.

The Re[590] of the first optical element is 240 to 350 nm, preferably 240 to 300 nm, more preferably 260 to 280 nm, particularly preferably 265 to 275 nm. The Re[590] is adjusted to about 1/2 of the measured wavelength, thereby increasing the oblique contrast of the liquid crystal display device.

In the specification of the present invention, Rth[590] refers to a retardation value in the thickness direction measured by light having a wavelength of 590 nm at 23°C. Rth[590] can be determined from the equation Rth[590]=(nx-nz)×d (wherein, nx and nz represent the refractive index of film slow axis direction and thickness direction under the wavelength of 590nm respectively, and d(nm) represents the film thickness). Note that the slow axis refers to the direction that provides the maximum in-plane refractive index.

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

Re[590] and Rth[590] can be measured using "KOBRA-21ADH" (trade name, manufactured by Oji Scientific Instruments (Oji Scientific Instruments Co., Ltd.)). The refractive indices nx, ny, and nz can be measured by using the in-plane retardation value (Re) of the film measured at 23°C using light having a wavelength of 590 nm, measured by inclining the slow axis by 40° as the inclination angle The retardation value (R40), the thickness (d) of the retardation film and the average refractive index (n0) of the retardation film, and then use the following equations (i) to (vi) to calculate the numerical calculation. Then, Rth can be calculated from the following equation (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 the specification of the present invention, Rth[590]/Re[590] refers to the ratio of the retardation value in the thickness direction and the in-plane retardation value measured at 23° C. using light having a wavelength of 590 nm.

Preferably, Rth[590]/Re[590] of the first optical element is 0.2 to 0.8, more preferably 0.2 to 0.7, further preferably 0.2 to 0.6, particularly preferably 0.4 to 0.6, most preferably 0.45 to 0.55. The Rth[590]/Re[590] of the retardation film being 0.5 can provide a substantially constant retardation regardless of the angle, and can increase the oblique contrast of the liquid crystal display device.

Preferably, the wavelength dispersion of the first optical element is 0.81 to 1.10, particularly preferably 0.95 to 1.05. Small wavelength dispersion in the above range provides a constant phase difference value in a wide range of visible light. Therefore, the oblique contrast of the liquid crystal display device can be increased, and the oblique color shift can be reduced. Note that the wavelength dispersion of the retardation film generally refers to the wavelength dependence of the retardation value. The wavelength dispersion can be represented by the ratio Re[480]/Re[590] of the in-plane retardation value Re measured at 23° C. using light having wavelengths of 480 nm and 590 nm. Note that Re[480] and Re[590] represent in-plane retardation values measured at 23°C using light with wavelengths of 480 nm and 590 nm, respectively.

D-2. Method of Arranging the First Optical Element

As a method of arranging the first optical element 30 between the liquid crystal cell 10 and the polarizer 20 , any appropriate method can be used according to purposes. The first optical element 30 is preferably attached to the polarizer 20 and the liquid crystal cell 10 by providing an adhesive layer or a pressure-sensitive adhesive layer (not shown) on both sides of the first optical element 30 . As a result, the contrast of the liquid crystal display device using the first optical element 30 can be increased.

The thickness of the adhesive or pressure-sensitive adhesive layer can be appropriately set according to the intended use, adhesive strength, and the like. However, its thickness is usually 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

Any suitable adhesive or pressure sensitive adhesive may be used to form the adhesive layer or pressure sensitive adhesive layer. Examples thereof include polymers each containing, for example, acrylic polymers, polysiloxane-based polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate/vinyl chloride copolymers, modified polyolefins, epoxy As the base polymer, the polymers listed above can be appropriately selected and used . In particular, acrylic presses are preferably used from the viewpoint of excellent optical transparency, adhesive properties including moderate wettability, cohesiveness, and adhesiveness, and excellent weather resistance and heat resistance. Sensitive adhesives.

Preferably, the first optical element 30 is arranged such that its slow axis is substantially parallel or perpendicular to the absorption axis of the adjacent polarizer 20 . More preferably, the first optical element 30 is arranged such that its slow axis is substantially parallel to the absorption axis of the adjacent polarizer 20, thereby allowing roll preparation of the film and promoting adhesion of the film. The production efficiency can thus be significantly improved. In the description of the present invention, the phrase "substantially parallel" includes the case where the slow axis of the first optical element 30 and the absorption axis of the polarizer 20 form an angle of 0°±2.0°, preferably 0°±1.0°, more preferably 0° °±0.5°. In the description of the present invention, the phrase "substantially perpendicular" includes the case where the slow axis of the first optical element 30 and the absorption axis of the polarizer 20 form an angle of 90°±2.0°, preferably 90°±1.0°, more preferably 90° °±0.5°. An angle greatly deviating from the above range may result in a decrease in the degree of polarization of the polarizing plate and a decrease in contrast when the first optical element is used in a liquid crystal display device.

D-3. Structure of the first optical element

The structure (laminated structure) of the first optical element is not particularly limited, as long as the first optical element includes a retardation film containing styrene-based resin and polycarbonate-based resin, and the first optical element satisfies the above-described part D-1. optical performance. Specifically, the first optical element may be a single-layer retardation film containing a styrene-based resin and a polycarbonate-based resin, a laminate of two or more retardation films, or a retardation film and other films (preferably each isotropic film) laminates. Preferably, the first optical element is a single-layer retardation film in order to reduce the shift or unevenness of the retardation value due to the shrinkage stress of the polarizer or the heat of the backlight and to reduce the thickness of the liquid crystal panel. The first optical element as a laminate may include an adhesive layer, a pressure-sensitive adhesive layer, or the like. In the case where the first optical element as a laminate includes two or more retardation films and/or two or more other films, the respective retardation films and/or other films may be the same as or different from each other. The polycarbonate-based resin, styrene-based resin, and other films will be described in detail below.

Re[590] used as the retardation film of the first optical element can be appropriately selected according to the number of retardation films to be used. For example, when the first optical element is formed of a single-layer retardation film, Re[590] of the retardation film is preferably equal to Re[590] of the first optical element. Therefore, it is preferable that the retardation of the pressure-sensitive adhesive layer, adhesive layer or the like used for laminating the first optical element on the polarizer or the liquid crystal cell is as small as possible. Furthermore, in the case where the first optical element is a laminate including two or more retardation films, it is preferable that the total Re[590] of the retardation film is designed to be equal to Re[590] of the first optical element. Specifically, in the case of using two retardation films, it is preferable to use retardation films each having Re[590] of 100 to 175 nm. Moreover, it is preferable that the slow axes of two retardation films are laminated|stacked in parallel.

Regardless of the number of retardation films used, it is preferable that Rth[590]/Re[590] of the retardation film is equal to Rth[590]/Re[590] of the first optical element. For example, the Rth[590]/Re[590]/Re An optical element with [590] of 0.5 and Re[590] of 280 nm.

Preferably the total thickness of the first optical element is 10 to 200 μm, more preferably 15 to 150 μm, particularly preferably 40 to 100 μm, most preferably 50 to 80 μm. The first optical member has a thickness within the above range, thereby providing a liquid crystal display device having excellent optical uniformity.

3A to 3H are each a schematic perspective view illustrating a typical preferred embodiment of the first optical element used in the present invention, including its relationship to the absorption axis of the polarizer. 3A to 3B each show a case where the first optical element 30 is a single-layer retardation film. Fig. 3 A has shown the situation that the slow axis of retardation film (first optical element) 30 is parallel to the absorption axis of polarizer 20, and Fig. 3 B has shown the slow axis of retardation film (first optical element) 30 is perpendicular to polarizer 20 case of absorbing shaft. In this embodiment mode, the retardation film also serves as a protective film for the polarizer on one side of the liquid crystal cell, thereby contributing to reducing the thickness of the liquid crystal cell. In addition, these embodiments are preferable from the viewpoint of the effect of reducing the shift or unevenness of the retardation value due to the shrinkage stress of the polarizer or the heat of the backlight. 3C and 3D each show a case where the first optical element 30 is a laminate of one retardation film 31 and other films (preferably isotropic films) 36 . FIG. 3C shows the situation that the slow axis of the retardation film 31 is parallel to the absorption axis of the polarizer 20 , and FIG. 3D shows the situation that the slow axis of the retardation film 31 is perpendicular to the absorption axis of the polarizer 20 . It is preferable to arrange another film 36 on one side of the polarizer 20 . In this embodiment, the other film serves as a protective film for the polarizer on one side of the liquid crystal cell. An isotropic film can be used as other films, thereby eliminating the adverse effect of the Rth of the conventional protective film on the polarizer. 3E and 3F each show the case where the first optical element 30 is a laminate of two retardation films 31 and 32, while FIGS. 3G and 3H each show that the first optical element 30 is two retardation films 31 and 32 and another film 36 in the case of a laminate. As described above, Re[590] of the retardation films 31 and 32 are each designed so that the total Re[590] is equal to Re[590] of the first optical element, and Rth[590]/Re[590] thereof are each designed to be equal to Rth[590]/Re[590] of the first optical element. For simplicity, the case where the first optical element 30 includes at most two retardation films and at most one other film is explained. However, the present invention can obviously be applied to laminates each having three or more retardation films and/or two or more other films.

D-4. Retardation film containing styrene resin and polycarbonate resin

As described above, the first optical element used in the present invention includes a retardation film containing a styrene-based resin and a polycarbonate-based resin (hereinafter may be referred to as a styrene/polycarbonate blend). The retardation film is a stretched polymer film containing a styrene-based resin and a polycarbonate-based resin. The polymer film containing styrene-based resin and polycarbonate-based resin used preferably has a small photoelastic coefficient and easily causes phase difference. In this retardation film, a styrene-based resin is used to reduce the photoelastic coefficient.

The photoelastic coefficient of the retardation film generally refers to the ease of causing birefringence when external pressure is applied on the optical film to cause internal stress. It is preferable that the absolute value of the photoelastic coefficient of the phase difference film is small so as to provide excellent optical uniformity and suppress unevenness of phase difference due to twist or the like. The photoelastic coefficient can be measured by measuring 2 cm × 10 cm under stress at 23° C. using a spectroscopic ellipsometer “M-220” (trade name, manufactured by JASCO Corporation (JASCO Corporation)) The in-plane retardation value of the sample is then calculated from the slope of the function of the retardation value and stress to the photoelastic coefficient.

Preferably, the absolute value of the photoelastic coefficient C[590] (m ² /N) of the retardation film measured using light having a wavelength of 590 nm at 23° C. is 2.0×10 ⁻¹¹ to 8.0×10 ⁻¹¹ , more preferably 2.0×10 −11 . 10 ^-11 to 6.0×10 ^-11 , particularly preferably 3.0×10 ^-11 to 6.0×10 ^-11 , most preferably 4.0×10 ^-11 to 6.0×10 ^-11 . A photoelastic coefficient within the above range can provide a retardation film that hardly causes shift or unevenness in retardation value due to shrinkage stress of a polarizer or heat of a backlight and has a relationship of nx>nz>ny. In the case of using a single-layer retardation film, the absolute value of the photoelastic coefficient of the retardation film is used as the absolute value of the photoelastic coefficient of the first optical element. The use of such a retardation film significantly improves the display non-uniformity in the oblique direction of the liquid crystal display device.

The thickness of the retardation film can vary depending on the number of laminated retardation films and the presence or absence of other films. Preferably, the total thickness of the obtained first optical element can be set to 10 to 200 μm, more preferably 15 to 150 μm, particularly preferably 40 to 100 μm, most preferably 50 to 80 μm. For example, in the case where the first optical element is formed of a single-layer retardation film, it is preferable that the thickness of the retardation film is 10 to 200 μm (ie, equal to the total thickness of the first optical element). In addition, for example, in the case where the first optical element is a laminate of two retardation films, each retardation film may have any suitable thickness as long as the total thickness of the retardation film is equal to the preferable total thickness of the first optical element . Therefore, the thicknesses of the retardation films may be the same as or different from each other. In an embodiment where two retardation films are laminated, it is preferable that one retardation film has a thickness of 5 to 100 μm, and the other retardation film has a thickness of 50 to 100 μm.

When the total solid content is taken as 100 parts by weight, the content of the styrene-based resin in the styrene/polycarbonate blend is preferably 10 to 40 parts by weight, more preferably 20 to 40 parts by weight, particularly preferably 22 to 38 parts by weight, Most preferably 25 to 35 parts by weight. The content of the styrene-based resin within the above range can sufficiently reduce the photoelastic coefficient of the retardation film, and can ensure a glass transition temperature (also referred to as Tg) or rigidity that meets durability, self-supporting performance, tensile performance, etc. . Therefore, it is possible to obtain a retardation film which causes little shift or unevenness in retardation value due to stress even when it is used for a liquid crystal display device and has a relationship of nx>nz>ny.

The content of the styrene-based resin can be determined by GPC measurement of a retardation film containing a styrene-based resin and a polycarbonate-based resin. Specifically, the retardation film was dissolved in tetrahydrofuran to prepare a 0.1% by weight solution, which was left to stand for 8 hours. Subsequently, the solution was filtered with a 0.45 μm membrane filter, and then the filtrate was measured by gel permeation chromatography (GPC). The resulting differential molecular weight distribution curve can be divided into low molecular weight components and high molecular weight components at the troughs between the peaks. The content of the styrene-based resin can be determined by the expression [total peak area of low molecular weight components/(total peak area of low molecular weight components+total peak area of high molecular weight components)]×100.

The styrenic resin refers to a styrenic polymer obtained by polymerizing a styrenic monomer by any appropriate method. Specific examples of styrenic monomers include styrene, α-methylstyrene and 2,4-dimethylstyrene. In addition, commercially available styrene-based resins and the like can be used. Specific examples thereof include styrene resins, acrylonitrile/styrene resins, acrylonitrile/butadiene/styrene resins, acrylonitrile/ethylene/styrene resins, styrene/maleimide copolymers, and styrene/maleimide copolymers. toric anhydride copolymer. Such monomers or resins may be used alone or in combination. In addition, styrenic resins and styrenic monomers may be used in combination.

Preferably, the weight average molecular weight (Mw) of the styrene-based resin measured by the GPC method using tetrahydrofuran as a developing solvent in terms of polystyrene is less than 20,000, more preferably 1,000 to 10,000, particularly preferably 1,000 to 6,000, most preferably 1,000 to 3,000. The styrene-based resin having a weight-average molecular weight within the above range can be uniformly mixed with the polycarbonate-based resin to provide a highly transparent film.

An aromatic polycarbonate composed of an aromatic dihydric phenol component and a carbonic acid component is preferably used as the polycarbonate-based resin for a phase difference film containing a styrene-based resin and a polycarbonate-based resin. Aromatic polycarbonates can generally be obtained by a reaction between an aromatic dihydric phenol compound and a carbonic acid precursor. That is, an aromatic polycarbonate can be obtained by a phosgene method in which phosgene is blown into an aromatic dihydric phenol compound in the presence of a caustic and a solvent; or a transesterification method in which In the presence, the aromatic dihydric phenol compound and the diaryl carbonate are transesterified. Specific examples of carbonic acid precursors include phosgene, dichloroformate of dihydric phenol, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-tolyl carbonate, Phenyl esters and dinaphthyl carbonates. Among them, phosgene and diphenyl carbonate are preferable.

Specific examples of the aromatic dihydric phenol compound reacted with the carbonic acid precursor include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-xylyl)propane, Bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy- 3,5-xylyl)butane, 2,2-bis(4-hydroxy-3,5-dipropylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane and 1, 1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane. Aromatic dihydric phenol compounds can be used alone or in combination. Preferable examples thereof include 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane and 1,1-bis(4-hydroxyphenyl)-3, 3,5-Trimethylcyclohexane. Particularly preferred is the combination of 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane to provide a sufficiently small Photoelastic coefficient and proper Tg and rigid retardation film.

Combined use of 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane as poly The carbonate-based resin contains repeating units represented by the following formulas (5) and (6).

In formulas (5) and (6), n represents an integer of 2 or more.

In case of combined use of 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane as aromatic dihydric phenol Next, by changing the ratio of 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane to The Tg or photoelastic coefficient of the retardation film is adjusted. For example, a high content of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexaneamine in a polycarbonate-based resin can increase Tg and decrease the photoelastic coefficient. The weight ratio of 2,2-bis(4-hydroxyphenyl) propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane in preferred polycarbonate resin is 2:8 to 8:2, more preferably 3:7 to 6:4, particularly preferably 3:7 to 5:5, most preferably 4:6. Combined use of 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane having the above weight ratio can provide A Tg and rigid retardation film that realizes excellent durability, self-supporting properties, and tensile properties.

In the case of using two or more kinds of aromatic dihydric phenol compounds, the group of aromatic dihydric phenol compounds can be determined by ¹ H-NMR measurement of a retardation film containing a styrene-based resin and a polycarbonate-based resin. weight ratio.

Preferably, the weight average molecular weight (Mw) of the polycarbonate-based resin used for the phase difference film containing the styrene-based resin and the polycarbonate-based resin measured by the GPC method using tetrahydrofuran as the developing solvent is 25,000 to 200,000 in terms of polystyrene , more preferably 30,000 to 150,000, particularly preferably 40,000 to 100,000, most preferably 50,000 to 80,000. A polycarbonate-based resin having a weight average molecular weight within the above range can provide a retardation film having excellent mechanical strength.

Preferably, the difference between the weight average molecular weights (Mw) of the polycarbonate-based resin and the styrene-based resin (Mw of the polycarbonate-based resin−Mw of the styrene-based resin) is 24,000 to 92,000, more preferably 29,000 to 87,000, Especially preferably 39,000 to 77,000, most preferably 49,000 to 67,000. A difference within the above range can provide a highly transparent retardation film having excellent mechanical strength.

The retardation film used in the present invention can be obtained by attaching a shrinkable film to one or both sides of a polymer film containing polycarbonate resin and styrene resin, and then passing The resulting product was stretched by a vertical uniaxial stretching method. The shrinkable film is used to provide shrinkage force in a direction perpendicular to the stretching direction during thermal stretching, and to increase the refractive index in the thickness direction of the retardation film. The method of attaching the shrinkable film to one or both sides of the polymer film is not particularly limited. However, its preferred method involves bonding the polymer film and the shrink film by providing an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer between the polymer film and the shrink film, because this method is Excellent performance in production rate and operability.

An example of a method of producing the retardation film of the present invention will be described with reference to FIG. 4 . Fig. 4 is a schematic diagram showing the concept of a typical production process of the retardation film of the present invention. For example, a polymer film 402 containing a styrene-based resin and a polycarbonate-based resin is conveyed by the first conveying member 401 . The shrinkable film 404 provided with a pressure-sensitive adhesive layer conveyed by the second conveying member 403 and the shrinkable film 406 provided with a pressure-sensitive adhesive layer conveyed by the third conveying member 405 are attached to the laminating rollers 407 and 408. Both sides of the polymer film 402. The laminate with the shrinkable film attached to both sides of the polymer film is subjected to tension in the longitudinal direction of the film (while under tension in the thickness direction of the shrinkable film) by rollers 410, 411, 412, and 413 at different speed ratios. The stretching treatment is performed while keeping the laminated body at a constant temperature by the heating device 409 . The shrinkable films 404 and 406 are peeled together with the pressure-sensitive adhesive layer from the stretch-treated laminate at a first take-up part 414 and a second take-up part 416 to obtain a phase Poor film (stretched film 418). The obtained retardation film 418 is wound on a third winding member 419 .

Polymer films containing styrenic resins and polycarbonate resins can be obtained from common solutions by casting or can be obtained by melt extrusion. The method of mixing the resins is not particularly limited. For example, in the case of producing a film by a casting method, a predetermined ratio of a polycarbonate-based resin and a styrene-based resin are mixed with a solvent and stirred to prepare a uniform solution. Also, in the case of producing each film by a melt extrusion method, predetermined ratios of polycarbonate-based resin and styrene-based resin are melted and mixed. The polymer film is preferably prepared from a solution by casting to provide a retardation film with good smoothness and good optical uniformity.

As described above, the shrinkable film is used to provide shrinkage force in a direction perpendicular to the stretching direction during thermal stretching, and to increase the refractive index in the thickness direction of the retardation film obtained. Examples of materials used for the shrink film include polyester, polystyrene, polyethylene, polypropylene, polyvinyl chloride, and polyvinylidene chloride. From the viewpoint of excellent shrinkage uniformity and heat resistance, a polypropylene film is preferably used.

Preferably the shrinkable film is a stretched film such as a biaxially stretched film or a uniaxially stretched film. The stretched film can be obtained by forming an unstretched film by an extrusion method, and then stretching the unstretched film in a longitudinal direction and/or a transverse direction at a predetermined stretching ratio using a simultaneous biaxial stretching machine or the like. Forming conditions and stretching conditions can be appropriately selected according to the purpose, the composition or kind of resin used, and the like. From the standpoint of excellent shrinkage uniformity and heat resistance, it is particularly preferable to use a biaxially stretched polypropylene film.

In one embodiment of the present invention, at 140° C., the shrinkage rate S ¹⁴⁰ (MD) of the shrinkable film in the machine direction is 2.7 to 9.4%, and the shrinkage rate S ¹⁴⁰ (TD) in the film width direction is 4.6 to 15.8%. In another embodiment of the present invention, at 160°C, the shrinkage rate S ¹⁶⁰ (MD) of the shrinkable film in the machine direction is 13 to 23%, and the shrinkage rate S ¹⁶⁰ (TD) in the width direction of the film is 30 to 48%. . A shrinkage ratio within the above range can provide a desired retardation value and a retardation film having excellent uniformity.

In one embodiment of the present invention, at 140°C, the difference between the shrinkage rate S ¹⁴⁰ (TD) in the width direction of the film and the shrinkage rate S ¹⁴⁰ (MD) in the longitudinal direction of the film is ΔS ¹⁴⁰ =S ¹⁴⁰ (MD)- S ¹⁴⁰ (TD) falls within the range of 0.1%≦ΔS ¹⁴⁰ ≦3.9%. In another embodiment of the present invention, at 160°C, the difference between the shrinkage ratio S ¹⁶⁰ (TD) in the film width direction and the shrinkage ratio S ¹⁶⁰ (MD) in the longitudinal direction of the film ΔS ¹⁶⁰ =S ¹⁶⁰ (MD) -S ¹⁶⁰ (TD) falls within the range of 8%≦ΔS ¹⁶⁰ ≦30%. The large shrinkage in the MD direction may cause difficulty in uniform stretching due to the shrinkage force of the retardation film in the stretching direction other than the stretching tension. A difference within the above range allows uniform stretching without applying an excessive load to equipment such as a stretching machine.

It is preferable that the shrinkage stress T _A ¹⁴⁰ (TD) per 2 mm in the width direction of the shrinkable film at 140° C. is 0.15 to 0.75 N/2 mm. It is preferable that the shrinkage stress T _B ¹⁴⁰ (TD) per unit area in the width direction of the shrinkable film at 140° C. is 2.5 to 12.5 N/mm ² . Shrinkage stress within the above range can provide the desired retardation value and allow uniform stretching.

Preferably, the shrinkage stress T _A ¹⁵⁰ (TD) per 2 mm in the width direction of the shrinkable film at 150° C. is 0.20 to 0.85 N/2 mm. Preferably, the shrinkage stress T _B ¹⁵⁰ (TD) per unit area in the width direction of the shrinkable film at 150° C. is 3.3 to 14.2 N/mm ² . Shrinkage stress within the above range can provide expected phase difference value and allow uniform stretching.

The shrinkage ratios S(MD) and S(TD) can be measured according to the thermal shrinkage ratio A method of JIS Z1712 (except that the heating temperature is changed from 120°C to 140°C or 160°C as described above and a load of 3 g is applied to the sample). Specifically, five samples having a width of 20 mm and a length of 150 mm were taken in the machine direction (machine direction MD) and width direction (transverse direction TD), respectively. Mark the center of each sample approximately 100 mm apart. Each sample with a load of 3 g was hung vertically in an air-circulating constant temperature oven maintained at 140°C±3°C or 160°C±3°C. The samples were heated for 15 minutes, removed from the oven, and left to stand for 30 minutes under standard conditions (room temperature). Subsequently, the distance between the marks was measured using a caliper according to JIS B7507, thereby obtaining an average value of five measured values. The shrinkage rate can be calculated by the equation S(%)=[(distance between marks before heating (mm)−distance between marks after heating (mm)/distance between marks before heating (mm))×100.

Commercially available shrink films for applications such as general packaging, food packaging, tray packaging, shrink labels, cap seals, and electrical insulation can be appropriately selected and used as the above-mentioned shrink film as long as the object of the present invention can be satisfied. A commercially available shrink film may be used as it is, or may be used after subjecting the shrink film to processing such as stretching treatment or shrinking treatment. Specific examples of commercially available shrinkable films include "ALPHAN" (trade name, produced by Oji paper Co. Ltd.), "FANCYTOP series" (trade name, Gunze, Ltd. (Gunze Co., Ltd.) production); "TORAYFAN series" (trade name, manufactured by Toray Industries, Inc.), "SUN·TOX-OP series" (trade name, manufactured by SUN·TOX Corporation) and "TOHCELLO OP series " (trade name, produced by TOHCELLO Co., Ltd.). In the process of thermally stretching a polymer film containing polycarbonate resin and styrene resin, it is preferable that the temperature in the stretching furnace (also referred to as stretching temperature) is at the glass transition temperature ( Tg) or higher because the retardation value of the resulting retardation film tends to be uniform, and the film hardly crystallizes (becomes moiré). Preferably, the stretching temperature is (Tg+1°C of the polymer film) to (Tg+30°C).

The glass transition temperature of the polymer film is not particularly limited. However, the glass transition temperature (Tg) is preferably 110 to 185°C, more preferably 120 to 170°C, particularly preferably 125 to 150°C. A Tg of 110°C or higher makes it easy to prepare films with good thermal stability. A Tg of 185° C. or lower makes it easy to control the in-plane retardation value and the retardation value in the thickness direction of the film by stretching. The glass transition temperature (Tg) can be measured by the DSC method according to JIS K7121.

The stretching ratio in the thermal stretching process of the polymer film is not particularly limited, and it can be determined according to the composition of the polymer film, the type of volatile components, etc., the residual amount of volatile components, etc., the designed retardation value, etc. to set appropriately. For example, a stretch ratio of 1.05 to 2.00 times is preferable. The transfer speed of the laminate (including polymer films and shrinkable films) during stretching is not particularly limited. However, in consideration of processing accuracy, stability, etc. of the stretching machine, the conveying speed is preferably 0.5 m/min or more, more preferably 1 m/min or more.

D-5. Other films for the first optical element

In the first optical element 30, other films that may be laminated on the retardation film containing polycarbonate-based resin and styrene-based resin preferably have a small absolute value of photoelastic coefficient.

Preferably, the film has an absolute value of photoelastic coefficient C[590] (m ² /N) of 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 -11 10 ^-12 to 6.0×10 ^-12 , most preferably 2.0×10 ^-12 to 5.0×10 ^-12 .

Materials used for film formation are preferably excellent in transparency, mechanical strength, thermal stability, water resistance, and the like. Specific examples thereof include polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; cellulose-based resins such as diacetyl cellulose and triacetyl cellulose; acrylic resins such as polymethylene methyl acrylate; styrenic resins such as polystyrene, acrylonitrile/styrene copolymer, styrene resin, acrylonitrile/styrene resin, acrylonitrile/butadiene/styrene resin, acrylonitrile/ethylene/ Styrene resins, styrene/maleimide copolymers, and styrene/maleic anhydride copolymers; and polycarbonate-based resins. Further examples thereof include cycloolefin-based resins; norbornene-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene/propylene copolymers; vinyl chloride-based resins; amide-based resins such as nylon and aramid ;imide resins, such as aromatic polyimides and polyimide amides; sulfone resins; polyethersulfone resins; polyether ether ketone resins; polyphenylene sulfide resins; vinyl alcohol resins; Vinylidene chloride-based resins; vinyl butyral-based resins; arylate-based resins; polyoxymethylene-based resins and epoxy-based resins. Still further examples thereof include polymer films composed of blended products of the above-mentioned resins.

Preferably the other membranes are isotropic membranes. In the specification of the present invention, an isotropic film refers to a film whose retardation value is small and does not affect optical properties in practical use. Such an isotropic film having a small birefringence or photoelastic coefficient can be laminated on a retardation film including a polycarbonate-based film and a styrene-based film. Therefore, the shrinkage stress of the polarizer or the heat of the backlight transmitted to the retardation film can be reduced, thereby further reducing the shift or unevenness of the retardation value. Such a retardation film containing polycarbonate resin and styrene-based dendrites hardly causes shift or unevenness in retardation value initially due to shrinkage stress of a polarizer or heat of backlight. Therefore, the isotropic film can be used in combination with the retardation film, thereby providing a liquid crystal panel having excellent display performance with very little shift or unevenness in the retardation value.

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

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

The thickness of the isotropic film may vary depending on the number of isotropic films and/or retardation films to be laminated. In practical applications, the thickness of the isotropic film can maintain proper mechanical strength without affecting the optical properties of the obtained first optical element. For example, in an embodiment where two retardation films and one isotropic film are laminated, it is preferable that the thickness of the isotropic film is 20 to 120 μm.

Specific examples of the material of the isotropic film satisfying the retardation value and the photoelastic coefficient include polymer modification by performing a ring-opening (co)polymer of a norbornene-based monomer ( For example, a norbornene-based resin prepared by adding maleic acid or cyclopentadiene) and hydrogenating a modified product, a norbornene-based resin prepared by addition polymerization of a norbornene-based monomer, and A norbornene-based resin produced by addition copolymerization of a norbornene-based monomer and an olefin-based monomer such as ethylene or α-olefin. Another example thereof includes the method described in JP 2002-348324A by using one of polycyclic cycloolefin monomers (such as norbornene), monocyclic cycloolefin monomers, and acyclic 1-olefin monomers in a metallocene catalyst. Cycloolefinic resins prepared in the form of solutions, suspensions or molten monomers, or in the gas phase, in the presence of

Further examples thereof include polycarbonate resins having 9,9-bis(4-hydroxyphenyl)fluorene on the side chain described in JP 2001-253960A and cellulose-based resins described in JP 07-112446A. Another example thereof includes the polymer film described in JP 2001-343529A, that is, a thermoplastic resin (A) containing substituted and/or unsubstituted imide groups on the side chain and Films obtained from resin compositions of substituted and/or unsubstituted phenyl and nitrile based thermoplastic resins (B). A specific example thereof is a polymer film obtained from a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile/styrene copolymer. Further examples thereof include formation of a polymer exhibiting positive birefringence as described in "Development and applied technology of optical polymer material" (pp. 194 to 207, published by NTS Corporation, 2003). monomers and random copolymers of monomers forming polymers exhibiting negative birefringence as well as polymers incorporating anisotropic low molecular weight molecules or birefringent crystals. However, the present invention is not limited thereto.

E. Second Optical Element

1, 2A and 2B, the second optical element 40 is disposed between the liquid crystal cell 10 and the polarizer 20'. The second optical element 40 has substantially optical isotropy. In the description of the present invention, the phrase "substantially optically isotropic" means that an optical element having a small retardation value does not substantially affect the optical properties of the entire liquid crystal panel and allows the liquid crystal cell optical compensation for birefringence. For example, optical elements substantially having optical isotropy include optical elements satisfying the following expressions (3) and (4).

0nm≤Re[590]≤10nm ...(3)

0nm≤Rth[590]≤20nm ...(4)

(In expressions (3) and (4), Re[590] and Rth[590] respectively represent the in-plane retardation value and the retardation value in the thickness direction of the film measured at 23°C using light with a wavelength of 590nm .)

In order to increase the oblique contrast of the liquid crystal display device, the second optical element has Re[590] as small as possible. In actual use, as described in expression (3), the Re[590] of the second optical element is 0 to 10 nm, preferably 0 to 5 nm, particularly preferably 0 to 2 nm, and most preferably 0 to 1 nm.

In order to increase the oblique contrast of the liquid crystal display device, the second optical element also preferably has an Rth [590] as small as possible. In actual use, as described in expression (4), the Rth[590] of the second optical element is 0 to 20 nm, preferably 0 to 5 nm, particularly preferably 0 to 3 nm, and most preferably 0 to 2 nm.

The method of arranging the second optical element between the liquid crystal cell 10 and the polarizer 20' is not particularly limited. Preferably, by disposing an adhesive layer or a pressure-sensitive adhesive layer (not shown) on both sides of the second optical element, and then attaching one side of the second optical element to one side of the polarizer 20' and The other side is attached to one side of the liquid crystal cell 10 leaving the second optical element 40 attached to the liquid crystal cell 10 and polarizer 20'. This can increase the contrast of the liquid crystal display device using the second optical element 40 . The thickness of the adhesive layer or pressure-sensitive adhesive layer can be appropriately set according to the intended use, adhesive strength, and the like. However, its thickness is usually 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

The adhesive or pressure-sensitive adhesive used to form the adhesive layer or the pressure-sensitive adhesive layer is not particularly limited. Examples thereof include polymers each containing, for example, acrylic polymers, polysiloxane-based polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate/vinyl chloride copolymers, modified polyolefins, epoxy As the base polymer, a quasi-polymer, a fluorine-based polymer, or a rubber-like polymer (for example, a natural rubber-like polymer or a synthetic rubber-like polymer) can be appropriately selected and used. In particular, acrylic pressure-sensitive adhesives are preferably used from the viewpoints of excellent optical clarity, adhesiveness (including moderate wettability, cohesiveness, and adhesiveness), and excellent weather resistance and heat resistance. .

The second optical element 40 basically has optical isotropy, but the slow axis can be detected in actual use. In this case, the second optical element 40 is preferably configured such that its slow axis is substantially parallel or perpendicular to the absorption axis of the adjacent polarizer 20'. More preferably, the second optical element 40 is configured such that its slow axis is substantially parallel to the absorption axis of the adjacent polarizer 20', thereby allowing roll production of the film and facilitating film adhesion. Therefore, production efficiency can be significantly improved. In the description of the present invention, the phrase "substantially parallel" includes the case where the slow axis of the second optical element 40 and the absorption axis of the polarizer 20' form an angle of 0°±2.0°, preferably 0°±1.0°, more preferably 0°±0.5°. In the description of the present invention, the phrase "substantially perpendicular" includes the case where the slow axis of the second optical element 40 and the absorption axis of the polarizer 20' form an angle of 90°±2.0°, preferably 90°±1.0°, more preferably 90°±0.5°. When the second optical element is used in a liquid crystal display device, a large deviation of the angle from the above range may cause a decrease in the degree of polarization of the polarizing plate and a decrease in contrast.

It is preferable that the second optical element has a thickness as small as possible within the range of providing self-supporting performance and mechanical strength of the film to reduce shift or non-uniformity of retardation value due to shrinkage stress of polarizer or heat of backlight. The thickness of the second optical element is usually 20 to 500 μm, more preferably 30 to 300 μm, particularly preferably 40 to 100 μm, most preferably 50 to 80 μm. The second optical member has a thickness within the above range, thereby providing a liquid crystal panel having excellent display uniformity.

The second optical element may be a single-layer optical film or a laminate of two or more optical films. For lamination of optical films, the second optical element as a laminate may contain an adhesive layer, a pressure-sensitive adhesive layer, or the like. The optical film may be an isotropic film or a retardation film as long as the entire second optical element has substantially optical isotropy. For example, in the case where two retardation films are laminated, it is preferable to arrange the retardation films so that the respective slow axes are perpendicular to each other, thereby reducing the in-plane retardation value.

The optical film is not particularly limited as long as it can satisfy the present invention, but it is preferable that the optical film has excellent transparency, mechanical strength, thermal stability, water barrier property, and the like. Specific examples of materials forming the optical film include polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; cellulose-based resins such as diacetyl cellulose and triacetyl cellulose; acrylic resins; resins such as polymethyl methacrylate; styrenic resins such as polystyrene, acrylonitrile/styrene copolymers, styrene resins, acrylonitrile/styrene resins, acrylonitrile/butadiene/styrene resins, Acrylonitrile/ethylene/styrene resins, styrene/maleimide copolymers, and styrene/maleic anhydride copolymers; and polycarbonate-based resins. Further examples thereof include cycloolefin-based resins; norbornene-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene/propylene copolymers; vinyl chloride-based resins; amide-based resins such as nylon and aramid ;imide resins, such as aromatic polyimides and polyimide amides; sulfone resins; polyethersulfone resins; polyether ether ketone resins; polyphenylene sulfide resins; vinyl alcohol resins; Vinylidene chloride-based resins; vinyl butyral-based resins; arylate-based resins; polyoxymethylene-based resins and epoxy-based resins. Still further examples thereof include polymer films composed of blended products of the above-mentioned resins.

Examples of the optical film include those similar to the isotropic film used for the first optical element. Among them, it is particularly preferable to use cellulose-based resins, A polymer film of at least one of norbornene-based resins and resins containing alternating copolymers of isobutylene and N-methylmaleimide and acrylonitrile/styrene copolymers.

In the case where the second optical element is formed by laminating a plurality of retardation films, the second optical element is usually formed by laminating the retardation films so that the refractive index distribution satisfying nx≈ny>nz The cathode uniaxial retardation film (also called the cathode C plate) and the anode uniaxial retardation film (also called the anode C plate) satisfying the refractive index distribution of nz>nx≈ny are laminated to eliminate each other’s in-plane The phase difference value and the phase difference value in the thickness direction (wherein, nx and ny represent the refractive index in the main plane, and nz represents the thickness refractive index). In the specification of the present invention, the expression "nx≈ny" is not strictly limited to the case showing the relationship of nx=ny, and the uniaxial retardation film includes a retardation film having Re[590] of 10 nm or less.

The method of laminating the cathode C-plate and the anode C-plate is not particularly limited, but it is preferable to attach them by providing an adhesive layer or a pressure-sensitive adhesive layer between the cathode C-plate and the anode C-plate. In addition, it is preferable to arrange the cathode C-plate and the anode C-plate so that the respective in-plane slow axes are perpendicular to each other to eliminate the in-plane retardation value. It is preferable that the second optical element use a laminated film prepared by laminating a cathode C-plate satisfying the following expressions (7) and (8) and an anode C-plate satisfying the following expressions (9) and (10).

0nm≤Re[590]≤10nm ...(7)

20nm≤Rth[590]≤400nm ...(8)

0nm≤Re[590]≤10nm ...(9)

-400nm≤Rth[590]≤-20nm...(10)

(In Expressions (7), (8), (9) and (10), Re[590] and Rth[590] respectively represent the in-plane retardation of the film measured at 23°C using light with a wavelength of 590nm and the phase difference in the thickness direction).

Preferably, the Re[590] of the cathode C plate is greater than 0 nm and less than or equal to 10 nm, more preferably greater than 0 nm and less than or equal to 3 nm, particularly preferably greater than 0 nm and less than or equal to 2 nm, most preferably greater than 0 nm and less than or equal to 1 nm.

Preferably, the Rth[590] of the cathode C plate is greater than 20nm and less than or equal to 400nm, more preferably greater than 20nm and less than or equal to 200nm, most preferably greater than 20nm and less than or equal to 100nm.

Preferably, the cathode C plate has a thickness of 20 to 500 μm, more preferably 30 to 300 μm, particularly preferably 40 to 100 μm, most preferably 50 to 80 μm.

Examples of materials for forming the cathode C plate include any suitable polymer film, a film prepared by curing a liquid crystal material exhibiting a cholesteric liquid crystal phase, a film prepared by curing a smectic liquid crystal compound, and Inorganic layered compounds. Specific examples of the polymer film forming the cathode C plate include cellulose-based resins such as diacetyl cellulose and triacetyl cellulose; acrylic resins such as polymethyl methacrylate; and polycarbonate-based resins. Further examples thereof include: cycloolefin-based resins; norbornene-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene/propylene copolymers; vinyl chloride-based resins; Amides; imide resins such as aromatic polyimides and polyimide amides; sulfone resins; polyethersulfone resins; polyether ether ketone resins; polyphenylene sulfide resins; vinyl alcohol resins ; vinylidene chloride-based resins; vinyl butyral-based resins; arylate-based resins; polyoxymethylene-based resins; and epoxy-based resins. Still further examples thereof include polymer films composed of blends of the above resins.

The polymer film used as the cathode C-plate may be obtained by film formation by casting or by stretching by any suitable stretching method. Specific examples of stretching methods include a vertical uniaxial stretching method, a transverse uniaxial stretching method, a vertical and transverse simultaneous biaxial stretching method, and a vertical and transverse sequential biaxial stretching method. The stretching method can be performed by using any suitable stretching machine, such as a roll stretching machine, a tenter frame or a biaxial stretching machine. Stretching can be done in two or more steps. The polymer film can be stretched in the machine direction (machine direction MD) or in the width direction of the film (transverse direction TD).

Examples of materials for forming the cathode C plate include: polyimide films described in paragraph [0100] of JP 2003-287750A; A film prepared by curing a liquid crystal monomer and a polymerizable chiral agent and a liquid crystal material exhibiting a cholesteric liquid crystal phase; a discotic liquid crystal non-alignment layer described in paragraph [0068] of JP 07-281028A; and a film prepared by coating a water-swellable inorganic layered compound on a substrate and drying the resulting product, as described in paragraph [0034] of JP 09-80233A. Preferably, the Re[590] of the anode C plate is greater than 0 nm and less than or equal to 10 nm, more preferably greater than 0 nm and less than or equal to 3 nm, particularly preferably greater than 0 nm and less than or equal to 2 nm, most preferably greater than 0 nm and less than or equal to 1 nm. Preferably, the Rth[590] of the anode C plate is greater than or equal to -400nm and less than -20nm, more preferably greater than or equal to -200nm and less than -20nm, most preferably greater than or equal to -100nm and less than -20nm.

The thickness of the anode C plate is preferably 0.1 to 50 μm, more preferably 0.1 to 30 μm, particularly preferably 0.1 to 10 μm, most preferably 0.1 to 5 μm. Examples of materials used to form the anode C plate include those described in Example 1 of JP 2002-174725A by coating the substrate with liquid crystalline (mesogenic) side chains, capable of forming vertical alignment, and by the following structural formula ( 11) A film prepared from the liquid crystal composition of the expressed liquid crystal polymer. Another example thereof includes the method described in Example 1 of JP 2003-149441 A, which contains a liquid crystal polymer expressed by the following structural formula (11) and a commercially available polymerizable liquid crystal monomer by coating a substrate with a solvent. A composition and a polymerization initiator, forming a uniform vertical alignment (also referred to as homeotropic alignment) of a polymerizable liquid crystal monomer, and then curing the obtained film to obtain a film.

5A and 5B are schematic perspective views each illustrating a typical preferred embodiment of a second optical element used in the present invention. FIG. 5A shows the case where the second optical element 40 is a single-layer isotropic film. FIG. 5B shows the case where the second optical element 40 is a laminate of the cathode C-plate 41 and the anode C-plate 42 . The cathode C-plate and the anode C-plate 42 are arranged such that the respective slow axes are perpendicular to each other. The second optical element is not limited to having the structure of Figures 5A and 5B, but may have any suitable substantially optically isotropic structure.

F. Polarizer protective film

A transparent film as a polarizer protective film can be configured on the side of the liquid crystal panel polarizer of the present invention that is not attached to the first optical element or the second optical element (that is, the polarizers 20 and 20 of FIGS. 1, 2A and 2B ’ outside).

It is preferable that the transparent film has excellent transparency, mechanical strength, thermal stability, water barrier property, and the like. Examples of materials for forming the transparent film include: polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; cellulose-based resins such as diacetyl cellulose and triacetyl cellulose Acrylic resins such as polymethyl methacrylate; Styrenic resins such as polystyrene, acrylonitrile/styrene copolymers, styrene resins, acrylonitrile/styrene resins, acrylonitrile/butadiene/benzene Vinyl resins, acrylonitrile/ethylene/styrene resins, styrene/maleimide copolymers, and styrene/maleic anhydride copolymers; and polycarbonate-based resins. Further examples thereof include: cycloolefin-based resins; norbornene-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene/propylene copolymers; vinyl chloride-based resins; Amides; imide resins such as aromatic polyimides and polyimide amides; sulfone resins; polyethersulfone resins; polyether ether ketone resins; polyphenylene sulfide resins; vinyl alcohol resins ; vinylidene chloride-based resins; vinyl butyral-based resins; arylate-based resins; polyoxymethylene-based resins; and epoxy-based resins. Still further examples thereof include polymer films composed of blends of the above resins. The surface of the transparent film to which no polarizer is attached may be subjected to hard coat treatment, antireflection treatment, antisticking treatment, or diffusion treatment (also referred to as antiglare treatment). Hard film treatment is to prevent damage to the surface of the polarizing plate, curable coating film with excellent hardness, slipperiness, etc. formed on the surface of the membrane. Anti-reflection treatment is for anti-reflection of external light on the surface of the polarizer. The anti-adhesive treatment is to prevent the adhesion of the polarizer to the adjacent layer. The anti-glare treatment is to prevent the external light reflection on the surface of the polarizing plate from interfering with the visual recognition of the light passing through the polarizing plate. A system in which transparent fine particles are mixed) is completed by providing an uneven fine structure on the surface of the transparent protective film. The anti-glare layer formed by the anti-glare treatment can also function as a diffusion layer for scattering light to pass through the polarizing plate and widen the viewing angle and the like (eg, viewing angle widening effect).

G. Other optical components

Next, a description will be given of other optical elements used in combination with the liquid crystal panel of the present invention. Any suitable optical element that can be used for a liquid crystal panel can be used as the other optical element. Examples thereof include optical films that have been hard-coated, antireflectively treated, antistickingly treated, or diffused (also called antiglare treated). In addition, the liquid crystal panel of the present invention can be used in combination with a commercially available brightness enhancement film (such as a polarization separation film with a polarization selective layer, D-BEF, manufactured by Sumitomo (Sumitomo) 3M Co., Ltd.), so as to obtain a better display performance. display device.

H. Liquid crystal display device

6 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. Note that the ratio between the length, width and thickness of each element in FIG. 6 is different from that of the actual element for clarity. The liquid crystal display device 200 is equipped with: a liquid crystal panel 100; protective layers 60 and 60' arranged on both sides of the liquid crystal panel; a brightness enhancement film 80 arranged outside the surface treatment layer 70' (backlight side); a prism sheet 110; a light guide plate 120 and backlight 130. Films subjected to hard coat treatment, antireflection treatment, antisticking treatment, diffusion treatment (also referred to as antiglare treatment), or the like are used as the surface treatment layers 70 and 70'. As the brightness enhancement film 80 , for example, a polarization separation film having a polarization selection layer “D-BEFseries” (trade name, manufactured by Sumitomo 3M Co., Ltd.) or the like is used. By using the above optical elements, a display device with better display performance can be obtained. As long as the effect of the present invention is obtained, the optical elements shown in FIG. 6 may be at least partially omitted or replaced by other elements according to the driving mode or the use of the liquid crystal cell.

The contrast ratio (YW/YB) at an azimuth angle of 45° and a polar angle of 60° is 20 or more, more preferably 30 or more, particularly preferably 50 or more, most preferably 80 or more.

I. Application of liquid crystal panel and liquid crystal display device of the present invention

The uses of the liquid crystal panel and liquid crystal display device of the present invention are not particularly limited, but the liquid crystal panel and liquid crystal display device of the present invention can be used in various applications, such as: office automation (OA) equipment, such as personal computer display devices, laptop Personal computers and copiers; portable devices such as mobile phones, watches, digital cameras, personal digital assistants (PDAs) and portable game consoles; home appliances such as video cameras, LCD TVs and microwave ovens; in-vehicle devices such as rear monitors, automotive Navigation system monitors and car audio; display devices, such as business information monitors; safety devices, such as monitors; and nursing and medical equipment, such as nursing monitors and medical monitors.

In particular, it is preferable that the liquid crystal panel and liquid crystal display device of the present invention be used for a large liquid crystal television. Preferably, the liquid crystal television screen size using the liquid crystal panel of the present invention and the liquid crystal display device is wide 17 inches (373mm * 224mm) or larger, more preferably wide 23 inches (499mm * 300mm) or larger, particularly preferably wide 26 inches (566mm × 339mm) or greater, most preferably 32 inches wide (687mm × 412mm) or greater. The present invention will be illustrated in more detail using the following Examples and Comparative Examples. The present invention is not limited to these examples. The analysis methods used in the examples are described below.

(1) Identification of polycarbonate-based resin: 1H-NMR measurement was performed using the following equipment under the following conditions, and the polycarbonate-based resin was determined from the integral ratio of the obtained spectral peaks. Analyzer: "JNM-EX400", manufactured by JEOL (Japan Electronics)

·RF core: 1H

·Frequency: 400MHz

·Pulse width: 45°

·Pulse repetition time: 10 seconds

·Measurement temperature: room temperature

(2) Method for measuring the molecular weight and content of styrene-based resins: the molecular weight and content of styrene-based resins are calculated by gel permeation chromatography using polystyrene as a standard. Specifically, the molecular weight and content of the styrene-based resin were measured using the following apparatus and tools under the following measurement conditions.

• Measurement sample: Dissolve the sample resin in tetrahydrofuran to prepare a 0.1 wt.% solution, and let it stand overnight. Then, the solution was filtered with a 0.45 μm membrane filter to obtain a filtrate for measurement.

Analyzer: "HLC-8120GPC", manufactured by Tosoh Corporation

Column: TSKgel SuperHM-H/H4000/H3000/H2000

·Column size: 6.0mm I.D.×150mm

·Eluent: tetrahydrofuran

·Flow rate: 0.6ml/min

Detector: RI

·Column temperature: 40℃

·Injection volume: 20μl

(3) Method of measuring glass transition temperature (Tg): The glass transition temperature was measured in accordance with JIS K7121 using the following equipment under the following measurement conditions.

・Analyzer: Differential scanning calorimeter "DSC500", manufactured by Seiko Instruments Electronics Co., Ltd.

Measuring gas: 20ml/min nitrogen flow

·Heating rate: 10℃/min

(4) Method for measuring phase difference, wavelength dispersion, slow axis angle and light transmittance: phase difference, wavelength dispersion, slow axis angle and light transmittance use light with a wavelength of 590nm at 23°C, according to parallel The Nicol rotation method was used for measurement using an automatic birefringence analyzer ("KOBRA-21ADH", trade name, manufactured by Oji Scientific Instruments Co., Ltd.).

(5) Method for measuring the photoelastic coefficient: the phase difference value of the sample is measured under stress using an ellipsometer "M-220" (trade name, manufactured by JASCO (Japan Spectroscopic) Co., Ltd.), and the photoelastic coefficient is determined by stress and phase Computation of the slope of the function of the difference. Specifically, the in-plane retardation value of a 2 cm×10 cm sample was measured at 23° C. using light having a wavelength of 590 nm under a stress of 5 N to 15 N.

(6) Method of measuring thickness: The thickness was measured using a digital micrometer "K-351C type" manufactured by Anritsu Corporation.

(7) The method of measuring the shrinkage rate of the shrinkable film: the shrinkage rate S(MD) and S(TD) are determined according to the thermal shrinkage rate A method of JIS Z1712 (except that the heating temperature is changed from 120°C to 140°C or 160°C; A load of 3 g was added to the sample). Specifically, five samples having a width of 20 mm and a length of 150 mm were selected from the machine direction (machine direction (MD)) and the width direction (transverse direction (TD)), respectively. Mark the center of each sample approximately 100 mm apart. Each sample with a load of 3 g was suspended vertically in an air-circulating constant temperature oven maintained at 140°C ± 3°C or 160°C ± 3°C. The samples were heated for 15 minutes, removed from the oven, and kept at standard conditions (room temperature) for 30 minutes. Then, according to JIS B7507, the distance between the marks was measured using a caliper, thereby obtaining an average of five measured values. The shrinkage rate can be calculated from the equation S(%)=[(distance between marks before heating (mm)-distance between marks after heating (mm))/distance between marks before heating (mm)]×100 .

(8) Method of Measuring Shrinkage Stress in the Width Direction (TD) of the Shrinkable Film: The shrinkage stress in the width direction was measured at 140° C. and 150° C. by the TMA method using the following equipment.

・Equipment: "TMA/SS 6100", manufactured by Seiko Instruments Co., Ltd.

・Data processing: "EXSTAR6000", manufactured by Seiko Instruments Co., Ltd.

·Measurement mode: constant temperature rise (10°C/min) measurement

Measuring gas: Atmospheric air (room temperature)

·Load: 20mN

·Sample size: 15mm×2mm (long side and width direction (TD))

·Film thickness: 60μm

(9) Contrast ratio of liquid crystal display device: The contrast ratio was calculated by the following liquid crystal cell and measuring equipment. A white image and a black image were displayed on a liquid crystal display device, and the Y value of the XYZ display system was measured at an azimuth angle of 45° and a polar angle of 60° of the display screen using "EZContrast 160D" (trade name, manufactured by ELDIM SA). The contrast "YW/YB" in the oblique direction is calculated from the Y value (YW) of the white image and the Y value (YB) of the black image. The azimuth of 45° refers to a direction rotated 45° counterclockwise from the long side of the panel at 0°.

・Liquid crystal unit: The liquid crystal unit installed in "KLV-17HR2", manufactured by Sony Corporation

·Panel size: 375mm×230mm

(10) Evaluation method of display unevenness of liquid crystal display device: The display screen was photographed using the following liquid crystal cell and measuring equipment. In Table 4, "good" refers to liquid crystal cells whose luminance difference across the panel is 1.5680 or less, and "not good" refers to liquid crystal cells whose luminance difference is greater than 1.7920.

・Liquid crystal unit: The liquid crystal unit installed in "KLV-17HR2", manufactured by Sony Corporation

·Panel size: 375mm×230mm

・Measuring equipment: Two-dimensional color distribution measuring equipment "CA-1500", manufactured by Konica Minolta (Konica Minolta) Holdings

·Measurement environment: dark room (23°C).

(Preparation Example 1)

Using phosgene as the carbonate precursor, while (A) 2,2-bis-(4-hydroxyphenyl)propane and (B) 1,1-bis(4-hydroxypropyl)-3,3,5- Trimethylcyclohexane is used as an aromatic dihydric phenol component to obtain a weight-average molecular weight (Mw) of 60,000 and a polycarbonate resin (number The average molecular weight (Mn) was 33,000, Mw/Mn was 1.78, and the weight ratio (A):(B) was 4:6). 70 parts by weight of a polycarbonate-based resin and 30 parts by weight of a styrene-based resin (HIMER SB75, Sanyo Chemical Industries, Inc. , Ltd. (manufactured by Sanyo Chemical Industry Co., Ltd.)) was added to 300 parts by weight of dichloromethane. The whole was mixed with stirring at room temperature for 4 hours, thereby preparing a clear solution. The solution was cast on a glass plate and allowed to stand at room temperature for 15 minutes. Next, the solution was peeled off from the glass plate and dried in an oven at 80°C for 10 minutes and then at 120°C for 20 minutes to obtain a polymeric film having a thickness of 55 μm and a glass transition temperature (Tg) of 140°C physical film. The light transmittance of the resulting polymer film was 93% at a wavelength of 590 nm. The in-plane retardation value Re[590] of this polymer film was 5.0 nm, the retardation value Rth[590] in the thickness direction was 12.0 nm, and the average refractive index was 1.576.

A biaxially stretched polypropylene film "TORAYFAN" (trade name, thickness 60 µm, manufactured by Toray Industries, Inc.) having the properties shown in Table 1 was passed through an acrylic pressure-sensitive adhesive layer (thickness: 15 μm) attached to both sides of the polymer film (thickness 55 μm). Subsequently, the resulting product was stretched 1.27 times using a roll stretcher at 147° C. (the temperature at 3 cm from the back of the film, with a temperature variation of ± 1° C.) in an air-circulating constant temperature furnace, while fixing the longitudinal direction of the film, thereby A retardation film A is prepared. Table 2 shows the stretching conditions and properties of the retardation film A obtained.

Table 1

The acrylic pressure-sensitive adhesive used in Preparation Example 1 was prepared by using isononyl acrylate synthesized by a solution polymerization method as a base polymer (weight average molecular weight: 550,000), and using the base polymer as 100 Parts by weight, 3 parts by weight of the cross-linking agent polyisocyanate compound "CORONATE L" (trade name, produced by Nippon Polyurethane Industry Co.Ltd. (Nippon Polyurethane Industry Co., Ltd.)) and 10 parts by weight of the catalyst "OL-1" (trade name Name, produced by Tokyo Fine Chemical Co.Ltd. (Tokyo Fine Chemical Co., Ltd.)) mixed.

The retardation film A obtained in Production Example 1 was dissolved in tetrahydrofuran to prepare a 0.1 wt % solution, which was left to stand for 8 hours. Subsequently, the solution was filtered with a 0.45 μm membrane filter, and the filtrate was subjected to GPC measurement. The content of the styrene-based resin measured by GPC measurement was 27 parts by weight when the total solid content was taken as 100 parts by weight.

The weight ratio of the aromatic dihydric phenol compound component was determined by performing ¹ H-NMR measurement on the retardation film A obtained in Production Example 1. Specifically, the polymer film was dissolved in chloroform, and the chloroform solution was added dropwise to 100 times the weight of methanol, thereby precipitating (reprecipitating) a white solid at 23°C. The solution was filtered and separated into methanol soluble and methanol insoluble fractions. The methanol-insoluble fraction was dissolved in chloroform-D for ¹ H-NMR measurement. As a result, the methyl peak of ^2,2 -bis(4-hydroxyphenyl)propane and 2.69ppm(6H) of 1,1-bis(4 The integral ratio of the peak of the methyl group substituted at the 3-position on the cyclohexyl ring of -hydroxyphenyl)-3,3,5-trimethylcyclohexane determined that the weight ratio of these components was 4:6.

(Preparation Example 2)

A retardation film B was prepared in the same manner as in Preparation Example 1, except that the stretch ratio was changed from 1.27 times to 1.30 times. Table 2 shows the stretching conditions and properties of the retardation film B obtained.

(Preparation Example 3)

A retardation film C was prepared in the same manner as in Preparation Example 1, except that the stretching temperature was changed from 147°C to 146°C and the stretching ratio was changed from 1.27 times to 1.25 times. Table 2 shows the stretching conditions and properties of the retardation film C obtained.

(Preparation Example 4)

A retardation film D was prepared in the same manner as in Preparation Example 1, except that the stretching temperature was changed from 147° C. to 145° C. and the stretching ratio was changed from 1.27 times to 1.20 times. Table 2 shows the stretching conditions and properties of the retardation film D obtained.

(Preparation Example 5)

A retardation film E was prepared in the same manner as in Preparation Example 1, except that the stretching temperature was changed from 147°C to 140°C and the stretching ratio was changed from 1.27 times to 1.10 times. Table 2 shows the stretching conditions and properties of the retardation film E obtained.

(Preparation Example 6)

The polycarbonate-based resin is obtained by a conventional method using phosgene as a carbonate precursor and bisphenol A as an aromatic dihydric phenol component. Next, a biaxially stretched polypropylene film was attached to both sides of a polymer film (60 μm in thickness) composed of a polycarbonate-based resin through an acrylic pressure-sensitive adhesive layer. Subsequently, the film was stretched 1.10 times using a roll stretcher at 147° C. (at a temperature of 3 cm from the back of the film, with a temperature variation of ± 1° C.) in an air-circulating constant temperature furnace while fixing the longitudinal direction of the film, thereby A retardation film F is obtained. Table 2 shows the properties of the retardation film F obtained. The biaxially stretched polypropylene film and the acrylic pressure-sensitive adhesive used in Production Example 6 were the same as those used in Production Example 1. Note that the glass transition temperature (Tg) of the polymer film composed of polycarbonate-based resin is 150°C, the retardation value in the front before stretching is 7 nm, and the retardation value in the thickness direction before stretching is 15 nm.

(Preparation Example 7)

Use an extruder to make 65 parts by weight of alternating copolymers made of isobutylene and N-methylmaleimide (the content of N-methylmaleimide is 50 mol%, and the glass transition temperature is 157° C.) , 35 parts by weight of acrylonitrile/styrene copolymer (acrylonitrile content is 27mol%) and 1 part by weight of 2-(4,6-diphenyl-1,3,5-triazine-2 base)-5 - Hexyloxy-phenol (ultraviolet absorber) shaped into pellets. Subsequently, the pellets were dried at 100°C for 5 hours, and then extruded at 270°C using a 40 nmΦ single-screw extruder and a T-die with a width of 400 nm. The sheet-shaped molten resin was cooled in a cooling drum, thereby preparing a polymer film G having a width of about 600 mm in width and a thickness of about 40 μm. Table 3 shows the properties of polymer film G.

(Preparation Example 8)

As the polymer film H, a commercially available norbornene-based resin film "ZEONOR ZF14-040" (trade name, thickness 40 μm, Zeon Corporation) was used. Table 3 shows the properties of polymer H.

(Preparation Example 9)

20 parts by weight of norbornene-based resin "ARTON" (manufactured by JSR Corporation) was added to 80 parts by weight of cyclopentanone to prepare a solution. This solution was placed on a triacetyl cellulose film "UZ-TAC" (trade name, Re[590] is 2.2 nm, Rth[590] is 39.8 nm, manufactured by Fuji Photo Film Co. Ltd. (Fuji Film Corporation)) It was coated to a thickness of 150 μm, and then the resulting product was dried at 140° C. for 3 minutes. After drying, the norbornene-based film formed on the surface of the TAC film was peeled off to obtain a transparent cellulose-based resin film, which was referred to as polymer film I. Table 3 shows the properties of Polymer Membrane I.

(Preparation Example 10)

Using a gravure coater, an ethyl silicate solution (2 wt% mixed solution of ethyl acetate and isopropanol, manufactured by COLCOAT Co., Ltd.) was applied to a polyethylene terephthalate film "S-27E" (thickness: 75 μm, produced by Toray Industries, Inc. (Toray Industries Co., Ltd.). The resulting product was dried at 130° C. for 30 seconds, thereby forming a glass polymer film having a thickness of 0.1 μm.

5 parts by weight of a liquid crystal polymer (weight-average molecular weight (Mw) of 5,000) having mesogenic side chains, capable of forming homeotropic alignment and represented by the following molecular formula (11), 20 parts by weight of a commercially available polymerizable liquid crystal single Body "Paliocolor LC242" (trade name, manufactured by BASFAktiengesellschaft (Basfer Group)) and 1.25 parts by weight of photopolymerization initiator "IRGACURE 907" (trade name, manufactured by Ciba Specialty Chemicals (Ciba Specialty Chemicals)) were dissolved in 75 parts by weight of cyclohexanone to prepare a mixed solution. This mixed solution was coated onto a glass polymer film laminate (polyethylene terephthalate film/glass polymer film) as a substrate using a paint bar. The resulting product was dried in an air-circulating constant temperature oven at 80°C±1°C for 2 minutes, and then cooled to room temperature, thereby forming a liquid crystal layer of polymerizable liquid crystal monomers fixed on a substrate with homeotropic alignment. Next, the liquid crystal layer was irradiated with ultraviolet light of 400 mJ/cm ² from the side on which the mixed solution was applied (using an irradiation device having a metal halide lamp as a light source). The polymerizable liquid crystal monomer is cured to produce an anode C-plate on the substrate. The thickness of the obtained anode C plate was 0.55 μm, Re[590] was 0.1 nm, and Rth[590] was −55.2 nm.

The anode CC plate was peeled off from the substrate and laminated on a commercially available triacetyl cellulose film "UZ-TAC" (trade name, Re[590] of 2.5 nm, Rth[590] of 60.2 nm) with a thickness of 80 μm , Fuji Photo Film Co. Ltd. (manufactured by Fuji Photo Film Co., Ltd.), so that the respective slow axes are perpendicular to each other, thereby preparing a polymer film J. Table 3 shows the properties of Polymer Film J.

(Preparation Example 11)

As the polymer film K, a commercially available norbornene-based resin film "ZEONOR ZF14-100" (trade name, thickness 100 μm, manufactured by Zeon Corporation) was used. Table 3 shows the properties of polymer film K.

(Preparation Example 12)

As the polymer film L, a commercially available triacetyl cellulose film “UZ-TAC” (trade name, thickness 40 μm, Fuji Photo Film Co. Ltd.) was used. Table 3 shows the properties of polymer film L.

(Preparation Example 13)

As the polymer film M, a commercially available triacetyl cellulose film "UZ-TAC" (trade name, thickness 80 μm, purchased from Fuji Photo Film Co. Ltd.) was used. Table 3 shows the properties of the polymer film M.

(Example 1)

The polyvinyl alcohol film was colored in an iodine-containing aqueous solution and then uniaxially stretched 6 times between rollers with different speed ratios in a boric acid-containing aqueous solution to obtain two polarizers P1 and P2. The obtained polarizers P1 and P2 each had a water content of 23%, a thickness of 28 μm, a degree of polymerization of 99.9%, and a uniaxial light transmittance of 43.5%. Next, the liquid crystal panel was taken out from a liquid crystal display device "KLV-17HR2" (manufactured by Sony Corporation) including an IPS mode liquid crystal cell. The polarizing plates disposed on the upper and lower sides of the liquid crystal cell were removed, and the glass surfaces (front and rear surfaces) were cleaned.

Next, the retardation film A was laminated as the first optical element on the surface of the liquid crystal cell from the viewing side so that the long side of the liquid crystal cell and the slow axis of the retardation film A were parallel to each other. Subsequently, the polarizer P1 was laminated on the surface of the retardation film A such that the slow axis of the retardation film A and the absorption axis of the polarizer P1 were parallel to each other (0°±0.5°). Subsequently, a commercially available triacetyl cellulose film "UZ-TAC" (trade name, thickness 40 μm, manufactured by Fuji Photo Film Co. on the surface of the polarizer P1.

Next, the polymer film G was laminated as a second optical member on the surface of the liquid crystal cell from the backlight side so that the short side of the liquid crystal cell and the slow axis of the polymer film G were parallel to each other. Subsequently, 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 absorption axis of the polarizer P2 were parallel to each other (0°±0.5°). Subsequently, a commercially available triacetyl cellulose film "UZ-TAC" (trade name, 40 μm in thickness, produced by Fuji Photo Film Co. On the surface of the polarizer P2, the O-mode liquid crystal panel I having the same structure as that shown in FIG. 2A is prepared. The absorption axes of the polarizers P1 and P2 in the thus prepared liquid crystal panel were perpendicular to each other (90°±1.0°).

The liquid crystal panel was incorporated into an original liquid crystal display device, and then the backlight was turned on for 10 minutes to measure oblique contrast. Table 4 shows the properties obtained.

Subsequently, the backlight was turned on for another 8 hours, and then the liquid crystal display device was displayed in a dark room using a two-dimensional color distribution measuring device "CA-1500" (manufactured by Konica Minolta Holdings, Inc.) screen camera. As shown in FIG. 7, there is almost no display unevenness due to the heat of the backlight.

(Example 2)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the first optical element was changed from retardation film A to retardation film B. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(Example 3)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the first optical element was changed from retardation film A to retardation film C. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(Example 4)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the first optical element was changed from a retardation film A to two retardation films E. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained. The two retardation films E are laminated so that the respective slow axes are parallel to each other.

(Example 5)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the second optical member was changed from polymer film G to polymer film H. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(Example 6)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the second optical member was changed from polymer film G to polymer film J. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(Example 7)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the second optical member was changed from polymer film G to polymer film K. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(Embodiment 8)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the second optical element was changed from a polymer film G to two polymer films K, and the two polymer films K were laminated so that the respective slow axes were mutually vertical. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(comparative example 1)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the first optical element was changed from retardation film A to retardation film D. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(comparative example 2)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the first optical element was changed from retardation film A to retardation film E. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(comparative example 3)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the second optical member was changed from the polymer film G to the polymer film L. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(comparative example 4)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the second optical member was changed from the polymer film G to the polymer film M. Subsequently, the oblique contrast ratio of the liquid crystal device incorporating the liquid crystal panel was measured. Table 4 shows the properties obtained.

(comparative example 5)

A liquid crystal panel was prepared in the same manner as in Example 1, except that the first optical element was changed from retardation film A to retardation film F. The liquid crystal panel was incorporated into an original liquid crystal display device, and the backlight was turned on for 8 hours. Subsequently, 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 Konica Minolta Holdings, Inc.). As shown in FIG. 8, there is large display unevenness largely due to the backlight.

(evaluate)

As shown in Examples 1 to 4, a liquid crystal display device with high oblique contrast ratio is obtained, and the liquid crystal display device includes a second optical element with a small retardation value and a first optical element with a Re[590] value in the range of 240 to 350 nm. element. Furthermore, as shown in Examples 5 to 8, a liquid crystal display device having a high oblique contrast ratio including the second optical element having an Rth[590] value in the range of 0 to 20 nm was obtained. The liquid crystal display device including the liquid crystal panel of Example 1 had almost no small display unevenness due to heat of the backlight even when the backlight was turned on for a long time. Similar to Examples, each of the liquid crystal display devices of Examples 2 to 8 had almost no display unevenness. However, Comparative Examples 1 to 4 each provided a liquid crystal display device having a low oblique contrast because the liquid crystal display device included the first optical element and the second optical element each having a retardation value outside the above-mentioned range. As shown in Comparative Example 5, a liquid crystal display device including a liquid crystal panel using a retardation film having a large photoelastic coefficient obtained by a conventional technique has display unevenness largely due to heat of a backlight.

As described above, the liquid crystal panel of the present invention has an increased oblique contrast ratio, and thus is very useful for improving the display performance of a liquid crystal display device. Therefore, the liquid crystal panel of the present invention can be suitably used in a liquid crystal display device or a liquid crystal television.

Many other changes will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is to be understood that the scope of the appended claims is not meant to be limited by the specific content of the specification, but rather interpreted broadly.

Claims (20)

1. liquid crystal panel comprises:

Liquid crystal cells;

Be configured in the polaroid of described liquid crystal cells both sides;

Be configured in first optical element between a polaroid and the described liquid crystal cells; And

Be configured in second optical element between another polaroid and the described liquid crystal cells, wherein:

Described first optical element comprises and contains styrene resin and polycarbonate resin and satisfy the phase retardation film of following formula (1) and (2); And

Described second optical element has optical isotropy basically,

240nm≤Re[590]≤350nm …(1)

0.20≤Rth[590]/Re[590]≤0.80…(2)

In described expression formula (1) and (2), Re[590] and Rth[590] represent respectively under 23 ℃, the use wavelength is the interior phase difference value of face of the measured described film of the light of 590 nm and the phase difference value of thickness direction.

2. liquid crystal panel according to claim 1, the absorption axes of the slow axis of wherein said first optical element and a polaroid substantially parallel and with the absorption axes perpendicular of another polaroid.

3. liquid crystal panel according to claim 1, wherein said liquid crystal cells comprise the liquid crystal layer that contains the nematic crystal of even orientation under the situation that does not have electric field.

4. liquid crystal panel according to claim 3, the index distribution of wherein said liquid crystal layer are nx＞ny=nz, and wherein nx, ny and nz represent the refractive index of film at slow-axis direction, quick shaft direction and thickness direction respectively.

5. liquid crystal panel according to claim 4, wherein said liquid crystal cells comprise a kind of in IPS pattern and the FFS pattern.

6. liquid crystal panel according to claim 1, the initial alignment direction of wherein said liquid crystal cells are arranged essentially parallel to the polaroid absorption axes direction of described second optical element, one side of configuration.

7. liquid crystal panel according to claim 6, the initial alignment direction of wherein said liquid crystal cells is arranged essentially parallel to the absorption axes direction of the polaroid that is configured in described liquid crystal cells backlight side.

8. liquid crystal panel according to claim 6, the initial alignment direction of wherein said liquid crystal cells is substantially perpendicular to the absorption axes direction of the polaroid that is configured in described liquid crystal cells backlight side.

9. liquid crystal panel according to claim 1, the wavelength dispersion of wherein said first optical element is 0.81 to 1.10.

10. liquid crystal panel according to claim 1, wherein said first optical element comprises the individual layer phase retardation film that contains styrene resin and polycarbonate resin.

11. comprising, liquid crystal panel according to claim 1, wherein said first optical element comprise the described laminate that contains the phase retardation film of styrene resin and polycarbonate resin.

12. liquid crystal panel according to claim 1, wherein with total solids content during as 100 weight portions, the content of styrene resin is 10 to 40 weight portions in the described phase retardation film.

13. liquid crystal panel according to claim 1, the polycarbonate resin in the wherein said phase retardation film contain the repetitive by formula (5) and (6) representative.

14. liquid crystal panel according to claim 1, it is 2.0 * 10 as the photo measure of 590nm that the absolute value of the photoelastic coefficient of wherein said phase retardation film uses wavelength down at 23 ℃ ^-11To 8.0 * 10 ^-11m ²/ N.

15. liquid crystal panel according to claim 1, wherein said second optical element satisfies following formula (3) and (4),

0nm≤Re[590]≤10nm …(3)

0nm≤Rth[590]≤20nm …(4)

In expression formula (3) and (4), Re[590] and Rth[590] represent respectively that to use wavelength down at 23 ℃ be the phase difference value of phase difference value and thickness direction in the face of film of photo measure of 590 nm.

At least aly be selected from cellulosic resin, norbornene resin and contain isobutylene and the alternating copolymer of N-methyl maleimide and the polymer film of vinyl cyanide/styrol copolymer 16. liquid crystal panel according to claim 1, wherein said second optical element comprise.

17. liquid crystal panel according to claim 1, wherein said second optical element comprise by the negative electrode C plate that satisfies following formula (7) and (8) and the positive C plate that satisfies following formula (9) and (10) are carried out the prepared laminated film of lamination,

0nm≤Re[590]≤10nm …(7)

20nm≤Rth[590]≤400nm …(8)

0nm≤Re[590]≤10nm …(9)

-400nm≤Rth[590]≤-20nm …(10)

In expression formula (7), (8), (9) and (10), Re[590] and Rth[590] represent respectively 23 ℃ use down wavelength as the face of the film of the photo measure of 590nm in the phase difference value of phase difference value and thickness direction.

18. liquid crystal panel according to claim 1, its outside at each polaroid further comprises diaphragm.

19. LCD TV that contains the described liquid crystal panel of claim 1.

20. liquid crystal indicator that contains the described liquid crystal panel of claim 1.

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