JP2008102227A - Liquid crystal panel and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal panel showing a high contrast ratio in a front direction and an oblique direction.
A liquid crystal cell, a first polarizing plate disposed on a viewing side of the liquid crystal cell, a second polarizing plate disposed on a backlight side of the liquid crystal cell, the liquid crystal cell and the liquid crystal cell And a first O plate disposed between the liquid crystal cell and the second polarizing plate, and at least a second O plate disposed between the liquid crystal cell and the second polarizing plate, A liquid crystal panel is used in which the transmittance (T ₂ ) of the _second polarizing plate is larger than the transmittance (T ₁ ) of the first polarizing plate.
[Selection] Figure 1

Description

  The present invention relates to a liquid crystal panel including two polarizing plates having different transmittances.

A liquid crystal display (hereinafter referred to as LCD) is an element that displays characters and images by utilizing the electro-optical characteristics of liquid crystal molecules. One of the driving modes of the LCD is a twisted nematic (TN) mode. Conventionally, the TN mode LCD has a drawback that the viewing angle in the vertical direction is narrow, and when the screen is viewed from an oblique direction, there is a problem that the sharpness of characters and images is remarkably reduced. In order to solve this problem, for example, a liquid crystal display device using an O plate and a biaxial retardation layer is disclosed. (For example, refer to Patent Document 1). In recent years, LCDs have been required to obtain a high contrast ratio that allows characters and images to be drawn more clearly as high-definition advances and uses are diversified.
JP 2001-100031 A

  An object of the present invention is to provide a liquid crystal panel exhibiting a high contrast ratio in the front direction and the oblique direction.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by a liquid crystal panel shown below, and have completed the present invention.

The liquid crystal panel of the present invention includes a liquid crystal cell, a first polarizing plate disposed on the viewing side of the liquid crystal cell, a second polarizing plate disposed on the backlight side of the liquid crystal cell, and the liquid crystal cell. Comprising at least a first O plate disposed between the first polarizing plate and a second O plate disposed between the liquid crystal cell and the second polarizing plate, The transmittance (T ₂ ) of the _second polarizing plate is larger than the transmittance (T ₁ ) of the _first polarizing plate.

In a preferred embodiment, the difference (ΔT = T ₂ −T ₁ ) between the transmittance (T ₂ ) of the _second polarizing plate and the transmittance (T ₁ ) of the first polarizing plate is 0. 1% to 6.0%.

  In a preferred embodiment, the liquid crystal cell is disposed on a liquid crystal layer, a first substrate disposed on the first polarizing plate side of the liquid crystal layer, and on the second polarizing plate side of the liquid crystal layer. Each of the first substrate and the second substrate each has an alignment film subjected to alignment treatment on the liquid crystal layer side.

  In a preferred embodiment, the liquid crystal layer is aligned in a twist arrangement in the absence of an electric field.

In a preferred embodiment, the transmittance of the first polarizing plate (T ₁₎ is a 38.3% ～43.3%.

In a preferred embodiment, the transmittance (T ₂ ) of the second polarizing plate is 41.1% to 44.3%.

  In a preferred embodiment, the degree of polarization of the first polarizing plate and / or the second polarizing plate is 99% or more.

  In a preferred embodiment, the first polarizing plate and the second polarizing plate include a first polarizer and a second polarizer, respectively, and the first polarizer and the second polarizer are included. However, the main component is a polyvinyl alcohol-based resin containing iodine.

  In a preferred embodiment, the first and second O plates are formed from a solidified layer or a hardened layer of a rod-like liquid crystal compound aligned in a hybrid arrangement.

  In a preferred embodiment, the first and second O plates are formed from a solidified layer or a hardened layer of a disk-like liquid crystal compound aligned in a hybrid arrangement.

  In a preferred embodiment, the direction in which the optical axis direction of the first and second O plates is projected onto the liquid crystal cell surface is substantially the same as the alignment processing direction of the liquid crystal cell.

  In a preferred embodiment, the slow axis of the first O plate is substantially parallel to the absorption axis of the first polarizing plate, and the slow axis of the second O plate is the second axis. It is substantially parallel to the absorption axis of the polarizing plate.

  In a preferred embodiment, a first biaxial retardation layer is further provided between the liquid crystal cell and the first O plate, and a second biaxial retardation layer is provided between the liquid crystal cell and the second O plate. A biaxial retardation layer is further provided.

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

  The liquid crystal display device including the liquid crystal panel of the present invention has a contrast ratio in a front direction and an oblique direction as compared with a conventional liquid crystal panel by disposing two polarizing plates with adjusted transmittance on both sides of the liquid crystal cell. Remarkably high and exhibits excellent display characteristics.

<A. Overview of Liquid Crystal Panel of the Present Invention>
The liquid crystal panel of the present invention includes a liquid crystal cell, a first polarizing plate disposed on the viewing side of the liquid crystal cell, a second polarizing plate disposed on the backlight side of the liquid crystal cell, the liquid crystal cell and the first At least a first O plate disposed between the polarizing plate and a second O plate disposed between the liquid crystal cell and the second polarizing plate, the transmittance of the second polarizing plate ( T ₂ ) is larger than the transmittance (T ₁ ) of the first polarizing plate. Such a liquid crystal panel has a contrast ratio in a front direction and an oblique direction as compared with a conventional liquid crystal panel (typically, the transmittance of two polarizing plates arranged on both sides of a liquid crystal cell is the same). Is markedly high. Thus, using two polarizing plates with adjusted transmittance on both sides of the liquid crystal cell, the frontal contrast ratio is greatly improved, which is a finding first found by the present inventors. This is an unexpected and excellent effect.

The difference (ΔT = T ₂ −T ₁ ) between the transmittance (T ₂ ) of the _second polarizing plate and the transmittance (T ₁ ) of the first polarizing plate is preferably 0.1% to 6 0.0%, more preferably 0.1% to 5.0%, particularly preferably 0.2% to 4.5%, and most preferably 0.3% to 4.2%. . By using two polarizing plates having a transmittance difference in the above range, the liquid crystal panel of the present invention can obtain a liquid crystal display device having a higher contrast ratio in the front direction.

  FIG. 1 is a schematic cross-sectional view of a liquid crystal panel in a preferred embodiment of the present invention. FIG. 2 is a schematic perspective view of the liquid crystal panel. It should be noted that for the sake of clarity, the ratio of the vertical, horizontal, and thickness of each component shown in FIG. Further, the relationship between the angles of the rubbing directions 1 and 2, the absorption axes 3 and 4, the slow axes 5 and 6 and the director directions 7 and 8 shown in FIG. 2 is a relative relationship and is limited to FIG. Is not to be done. The liquid crystal panel 100 includes a liquid crystal cell 10, a first polarizing plate 21 disposed on the viewing side of the liquid crystal cell 10, a second polarizing plate 22 disposed on the backlight side of the liquid crystal cell 10, and a liquid crystal cell. 10 and the first polarizing plate 21, the first O plate 31 disposed between the liquid crystal cell 10 and the second polarizing plate 22, and the liquid crystal cell 10 and the second polarizing plate 22, the second biaxial position disposed between the first biaxial retardation layer 41 disposed between the liquid crystal cell 10 and the second O plate 32. And a phase difference layer.

  The second polarizing plate is disposed on the backlight side of the liquid crystal cell, and the first polarizing plate is disposed on the viewing side of the liquid crystal cell. If a polarizing plate with high transmittance is arranged on the backlight side and the backlight light is incident on the liquid crystal cell as much as possible, high brightness (white brightness) can be easily obtained when displaying a white image or color display. Because. On the other hand, when a black image is displayed by arranging a polarizing plate with low transmittance on the viewing side so that the light from the backlight is not leaked to the viewing side as much as possible, the luminance (black luminance) can be kept low. . As a result, a liquid crystal display device with a high contrast ratio can be obtained.

<B. Liquid crystal cell>
Referring to FIG. 1, a liquid crystal cell 10 used in the present invention includes a liquid crystal layer 13, a first substrate 11 disposed on the liquid crystal layer 13 on the first polarizing plate 21 side, and a second liquid crystal layer 13. And the second substrate 12 disposed on the polarizing plate 22 side. One substrate (active matrix substrate) is preferably provided with a scanning line for providing electro-optical characteristics of liquid crystal and a signal line for providing a source signal (not shown). The other substrate (color filter substrate) is provided with a color filter. Note that the color filter may be provided on the active matrix substrate. Alternatively, for example, when an RGB three-color light source (which may include a multicolor light source) is used as the illumination means of the liquid crystal display device as in the field sequential method, the color filter may be omitted. . The distance (cell gap) between the two substrates is controlled by a spacer (not shown).

  The first substrate and the second substrate each preferably have an alignment film subjected to alignment treatment on the liquid crystal layer 13 side. Any method can be adopted for the alignment film as long as the liquid crystal molecules are arranged in a certain alignment state on the surface of the substrate. As the alignment treatment, a rubbing method is preferably used in which a polymer film such as polyimide is applied and rubbed in one direction with fibers such as nylon or polyester. The alignment treatment direction is, for example, a rubbing direction when a rubbing method is used as the alignment treatment.

  The liquid crystal layer is preferably aligned in a twist arrangement in the absence of an electric field. Generally, the twist alignment is such that the liquid crystal molecules in the liquid crystal layer are aligned substantially parallel to the substrate surfaces on both sides, and the alignment direction is twisted by 90 ° on both substrate surfaces. A liquid crystal cell including such a liquid crystal layer in an aligned state is typically a twisted nematic (TN) mode liquid crystal cell. As the TN mode liquid crystal cell, a liquid crystal cell mounted on a commercially available liquid crystal display device can be used as it is. Examples of commercially available liquid crystal display devices adopting the TN mode include a 17-inch liquid crystal monitor product name “FP71E +” manufactured by BENQ and a 15-inch liquid crystal monitor product name “1503FP” manufactured by Dell.

<C-1. Polarizing plate>
As the polarizing plate (the first polarizing plate and the second polarizing plate) used in the present invention, any appropriate one can be adopted as long as the transmittance satisfies the above relationship. In this specification, “polarizing plate” refers to a material that converts natural light or polarized light into linearly polarized light. Preferably, the polarizing plate has a function of separating incident light into two orthogonally polarized components, transmitting one polarized component, and absorbing, reflecting and / or scattering the other polarized component.

  The thickness of the said polarizing plate is not specifically limited, The general concept of a thin film, a film, and a sheet is included. The thickness of the polarizing plate is preferably 1 μm to 250 μm, and more preferably 20 to 250 μm. By setting the thickness of the polarizing plate in the above range, a material having excellent mechanical strength can be obtained.

  The polarizing plate may be a single layer having a polarizing function (also referred to as a polarizer) or a laminate composed of a plurality of layers. When the polarizing plate is a laminate, examples of the configuration thereof include (a) a laminate including a polarizer and a protective layer (for example, the configuration of Examples); (b) a polarizer, a protective layer, and a surface treatment. And (c) a laminate containing two or more polarizers, and the like. The polarizing plate may have two or more surface treatment layers. Alternatively, in the polarizing plate, the protective layer may also have a function of expanding the viewing angle of the liquid crystal cell (a layer having such a function is also referred to as an optical compensation layer).

The transmittance (T ₁ ) of the first polarizing plate is preferably 38.3% to 43.3%, more preferably 38.6% to 43.2%, and particularly preferably 39.9. % To 43.1%, most preferably 39.2% to 43.0%. By setting T ₁ in the above range, a liquid crystal display device having a higher contrast ratio in the front direction can be obtained.

The transmittance (T ₂ ) of the second polarizing plate is preferably 41.1% to 44.3%, more preferably 41.5% to 44.3%, and particularly preferably 41.9%. % To 44.2%, and most preferably 42.3% to 44.2%. By setting T ₂ in the above range, a liquid crystal display device with a higher contrast ratio in the front direction can be obtained.

  The liquid crystal panel of the present invention can be produced by, for example, selecting commercially available polarizing plates having different transmittances and combining them appropriately. Preferably, the liquid crystal panel of the present invention is produced by appropriately adjusting the transmittance of the polarizing plate so as to increase the contrast ratio in the front direction according to the driving mode and application of the liquid crystal cell.

  As a method for increasing or decreasing the transmittance of the polarizing plate, for example, when a polarizer mainly composed of a polyvinyl alcohol resin containing iodine is used for the polarizing plate, the content of iodine in the polarizer The method of adjusting is mentioned. Specifically, if the iodine content in the polarizer is increased, the transmittance of the polarizing plate can be lowered, and if the iodine content in the polarizer is decreased, the transmittance of the polarizing plate is increased. can do. Note that this method can be applied to the production of a roll-shaped polarizing plate and various types of polarizing plates. The polarizer will be described later.

  The degree of polarization (P) of the first polarizing plate and / or the second polarizing plate is preferably 99% or more, more preferably 99.5% or more, and further preferably 99.8% or more. It is. By setting the degree of polarization (P) within the above range, a liquid crystal display device having a higher contrast ratio in the front direction can be obtained.

The degree of polarization can be measured using a spectrophotometer [product name “DOT3” manufactured by Murakami Color Research Laboratory Co., Ltd.]. As a specific method of measuring the degree of polarization, parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ) of the degree of polarization are measured, and the formula: degree of polarization (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100. The parallel transmittance (H ₀ ) is a value of transmittance of a parallel laminated polarizing plate produced by superposing two identical polarizing plates so that their absorption axes are parallel to each other. The orthogonal transmittance (H ₉₀ ) is a transmittance value of orthogonal orthogonal laminated polarizing plates produced by superposing two sheets having the same degree of polarization so that their absorption axes are orthogonal to each other. In addition, these transmittance | permeability is Y value which performed visibility correction | amendment by the 2 degree visual field (C light source) of JISZ8701-1982.

<C-2. Polarizer>
Any appropriate polarizer may be employed as the polarizer used in the present invention. Preferably, the first polarizing plate and the second polarizing plate each include a first polarizer and a second polarizer, and the first polarizer and the second polarizer are iodine. The main component is a polyvinyl alcohol-based resin containing The polarizer can be usually obtained by stretching a polymer film containing as a main component a polyvinyl alcohol-based resin containing iodine. A polarizing plate including such a polarizer is excellent in optical characteristics.

The relationship between the iodine content (I ₁ ) of the first polarizer and the iodine content (I ₂ ) of the second polarizing plate is preferably I ₁ > I ₂ . The difference (ΔI = I ₁ −I ₂ ) between the iodine content (I ₁ ) of the _first polarizer and the iodine content (I ₂ ) of the second polarizing plate is preferably 0.1 weight. % To 2.6% by weight, more preferably 0.2% to 1.9% by weight, particularly preferably 0.4% to 1.8% by weight, and most preferably 0.6% to 2.6% by weight. % By weight to 1.7% by weight. By making the relationship of the iodine content of each polarizer into the above range, a polarizing plate having a transmittance relationship in a preferable range can be obtained, and a liquid crystal display device having a high contrast ratio in the front direction can be obtained.

  The iodine content of the first polarizer and / or the second polarizer is preferably 1.8 wt% to 5.0 wt%, more preferably 2.0 wt% to 4.0 wt%. %. The iodine content of the first polarizer is preferably 2.3% by weight to 5.0% by weight, more preferably 2.5% by weight to 4.5% by weight, and particularly preferably 2.7 wt% to 4.0 wt%. The iodine content of the second polarizer is preferably 2.0% by weight and 3.5% by weight, more preferably 2.0% by weight to 3.2% by weight, and particularly preferably 2.0% by weight. % By weight to 2.9% by weight. By setting the iodine content of each polarizer in the above range, a polarizing plate having a transmittance in a preferable range can be obtained, and a liquid crystal display device having a high contrast ratio in the front direction can be obtained.

  Preferably, the first polarizer and / or the second polarizer further contain potassium. The potassium content is preferably 0.2% by weight to 1.0% by weight, more preferably 0.3% by weight to 0.9% by weight, and particularly preferably 0.4% by weight to 0.00%. 8% by weight. By making potassium content into the said range, the polarizing plate which has the transmittance | permeability of a preferable range and has high polarization degree can be obtained.

  Preferably, the first polarizer and / or the second polarizer further contain boron. The boron content is preferably 0.5 wt% to 3.0 wt%, more preferably 1.0 wt% to 2.8 wt%, and particularly preferably 1.5 wt% to 2. wt%. 6% by weight. By setting the boron content in the above range, a polarizing plate having a transmittance in a preferable range and a high degree of polarization can be obtained.

  The polyvinyl alcohol resin can be obtained by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer. The saponification degree of the polyvinyl alcohol resin is preferably 95.0 mol% to 99.9 mol%. The saponification degree can be determined according to JIS K 6726-1994. By using a polyvinyl alcohol resin having a saponification degree in the above range, a polarizer having excellent durability can be obtained.

  Content in the iodine atom and potassium atom of the polyvinyl alcohol can be measured using a fluorescent X-ray analyzer (XRF) [product name “ZSX100e” manufactured by Rigaku Corporation]. As a specific method for measuring the content of iodine atom and potassium atom, a calibration curve prepared in advance using standard data was prepared from the X-ray intensity of a circular sample having a diameter of 10 mm measured by fluorescent X-ray analysis under the following conditions. The content of each element can be determined. One specific example of the measurement method is rhodium as the counter cathode, lithium fluoride as the spectroscopic crystal, excitation light energy of 40 kV-900 mA, iodine measurement line as I-LA, potassium measurement line as K-KA, and quantitative method as The FP method, 2θ angle peak can be measured as 103.078 deg (iodine), 136.847 deg (potassium), and the measurement time can be 4 seconds.

  As the average degree of polymerization of the polyvinyl alcohol-based resin, an appropriate value can be appropriately selected according to the purpose. The average degree of polymerization is preferably 1200 to 3600. The average degree of polymerization can be determined according to JIS K 6726-1994.

  Any appropriate forming method can be adopted as a method for obtaining the polymer film containing the polyvinyl alcohol resin as a main component. Examples of the molding method include the method described in JP 2000-315144 A [Example 1].

  The polymer film containing the polyvinyl alcohol-based resin as a main component preferably contains a plasticizer and / or a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. The polyhydric alcohol is used for the purpose of further improving the dyeability and stretchability of the polarizer. As said surfactant, a nonionic surfactant is mentioned, for example. The surfactant is used for the purpose of further improving the dyeability and stretchability of the polarizer.

  A commercially available film can be used as it is as the polymer film containing the polyvinyl alcohol resin as a main component. Examples of the polymer film mainly composed of a commercially available polyvinyl alcohol-based resin include, for example, “Kuraray Vinylon Film” manufactured by Kuraray Co., Ltd., “Toselo Vinylon Film” manufactured by Tosero Co., Ltd., Nippon Synthetic Chemical Industry Product name “Nippon Vinylon Film”, etc., may be mentioned.

  An example of a method for manufacturing a polarizer will be described with reference to FIG. FIG. 3 is a schematic diagram showing the concept of an alternative manufacturing process for a polarizer used in the present invention. For example, a polymer film 301 mainly composed of a polyvinyl alcohol-based resin is fed from a feeding unit 300 and immersed in a swelling bath 310 containing pure water and a dyeing bath 320 containing an aqueous iodine solution, and rolls 311 having different speed ratios. , 312, 321 and 322, swelling treatment and dyeing treatment are performed while tension is applied in the longitudinal direction of the film. Next, the film subjected to the swelling treatment and the dyeing treatment is immersed in the first crosslinking bath 330 containing potassium iodide and the second crosslinking bath 340, and is rolled with rolls 331, 332, 341 and 342 having different speed ratios. While tension is applied in the longitudinal direction of the film, a crosslinking treatment and a final stretching treatment are performed. The film subjected to the crosslinking treatment is immersed in a washing bath 350 containing pure water by rolls 351 and 352 and subjected to a washing treatment. The water-washed film is dried by the drying means 360, so that the moisture content is adjusted to, for example, 10% to 30%, and is wound by the winding unit 380. The polarizer 370 can stretch the polymer film containing the polyvinyl alcohol-based resin as a main component to 5 to 7 times the original length through these steps.

In the dyeing step, the amount of iodine added to the dyeing bath for obtaining a polarizing plate having excellent optical properties is preferably 0.01 parts by weight to 0.15 parts by weight with respect to 100 parts by weight of water. More preferably, it is 0.01 weight part-0.05 weight part. When the amount of iodine added to the dyeing bath is reduced within the above range within the range of iodine in the dyeing bath, a polarizing plate having a high transmittance can be obtained as a result.

  The addition amount of potassium iodide in the dyeing bath is preferably 0.05 parts by weight, more preferably 0.1 parts by weight to 0.3 parts by weight with respect to 100 parts by weight of water. By setting the amount of potassium iodide to be in the above range, a polarizing plate having a preferable range of transmittance and a high degree of polarization can be obtained.

In the dyed polarizing plate, the amount of potassium iodide added to the first crosslinking bath and the second crosslinking bath to obtain a polarizing plate having excellent optical properties is preferably 100 parts by weight of water, It is 0.5 weight part-10 weight part, More preferably, it is 1 weight part-7 weight part. The amount of boric acid added in the first crosslinking bath and the second crosslinking bath is preferably 0.5 to 10 parts by weight, more preferably 1 to 7 parts by weight. By setting the amounts of potassium iodide and boric acid to be in the above ranges, a polarizing plate having a preferable range of transmittance and a high degree of polarization can be obtained.

  In practice, an optional protective layer or surface treatment layer may be disposed on the side of the first and / or second polarizer opposite to the side having the O plate. Further, an arbitrary adhesive layer may be provided between the constituent members of the liquid crystal panel. The “adhesive layer” refers to a layer that joins surfaces of adjacent members and integrates them with practically sufficient adhesive force and adhesion time. Examples of the material for forming the adhesive layer include an adhesive, a pressure-sensitive adhesive, and an anchor coating agent. The adhesive layer may have a multilayer structure in which an anchor coating agent is formed on the surface of an adherend and an adhesive layer or a pressure-sensitive adhesive layer is formed thereon. Further, it may be a thin layer (also referred to as a hairline) that cannot be visually recognized.

<D. O plate>
In this specification, the “O plate” refers to a retardation layer in which molecules are tilted. The thicknesses of the first O plate and the second O plate are usually 0.1 μm to 10 μm, preferably 0.5 μm to 5 μm.

  In one embodiment, the first and second O plates are formed from a solidified layer or a hardened layer of a rod-like liquid crystal compound aligned in a hybrid arrangement.

In the present invention, the “hybrid alignment” means a state in which the tilt angle (tilt angle) of the rod-like liquid crystal compound is increased or decreased continuously or intermittently in the thickness direction. The tilt angle (θ _P ) is different from the tilt angle (θ _B ) on the liquid crystal cell side.

The tilt angle of the adjacent interface of the rod-like liquid crystal compound is determined according to Journal of Applied Phisics Vol. 2 as shown in the following formulas (I) and (II). 38 (1999) p. The expression of Witte according to 748, premeasured n _e, n _o, and the phase difference layer (the slow axis direction parallel to the polar angle -40 ° ~ + 40 ° (the normal direction to 0 °) Each value measured in 5 ° increments) can be substituted. Here, θ _air represents the tilt angle of one side (for example, air interface) of the rod-like liquid crystal compound, and θ _AL represents the tilt angle of the other side (for example, substrate or alignment film) interface. d represents the thickness of the solidified layer or hardened layer of the rod-like liquid crystal compound aligned in a hybrid arrangement. n _e represents an extraordinary refractive index of the rod-like liquid crystal compound, n _o represents an ordinary refractive index of the rod-like liquid crystal compound.

  In the present specification, the “rod-like liquid crystal compound” has a mesogenic group in the molecular structure, and the refractive index in the major axis direction of the mesogenic group is larger than that in the minor axis direction, such as heating and cooling. The compound which shows a liquid crystal phase by the temperature change of this, or the effect | action of a certain amount of solvent. The “disc-like liquid crystal compound” is a molecule having a disc-like core and means a liquid crystal molecule exhibiting a disc phase and / or a discotic nematic phase. The “solidified layer” refers to a softened, melted or solution-state liquid crystalline composition that has been cooled and solidified, and the “cured layer” refers to a part or all of the liquid crystalline composition that is heat, catalyst, This refers to those that have been crosslinked by light and / or radiation to become insoluble or insoluble or hardly soluble. “Liquid crystal composition” refers to a liquid crystal phase exhibiting liquid crystallinity. However, the liquid crystalline composition exhibits liquid crystallinity before film formation, but after film formation, for example, a network structure may be formed by photopolymerization or the like, and the liquid crystal composition may no longer exhibit liquid crystallinity.

  Any appropriate one can be selected as the rod-shaped liquid layer compound. Preferably, the rod-like liquid crystal compound exhibits a crystalline or glass state at room temperature and develops a nematic liquid crystal phase at a high temperature. The rod-shaped liquid crystal compound exhibits a liquid crystal phase before film formation, but after film formation, for example, a network structure may be formed by a cross-linking reaction and no liquid crystal phase may be exhibited. If the rod-like liquid crystal compound having the above properties is used, for example, after forming a hybrid arrangement in a state showing a liquid crystal phase, the arrangement state can be fixed by cooling or crosslinking.

  The mesogenic group is a constituent part necessary for forming a liquid crystal phase and usually contains a cyclic unit. Specific examples of the mesogenic group include, for example, a biphenyl group, a phenylbenzoate group, a phenylcyclohexane group, an azoxybenzene group, an azomethine group, an azobenzene group, a phenylpyrimidine group, a diphenylacetylene group, a diphenylbenzoate group, a bicyclohexane group, and a cyclohexyl group. Examples thereof include a benzene group and a terphenyl group. In addition, the terminal of these cyclic units may have substituents, such as a cyano group, an alkyl group, an alkoxy group, a halogen group, for example. Especially, as a mesogenic group which consists of a cyclic unit etc., what has a biphenyl group and a phenylbenzoate group is used preferably.

  The rod-shaped compound may be a high molecular substance (polymer liquid crystal) having a mesogenic group in the main chain and / or side chain, or a low molecular substance (low molecular liquid crystal) having a mesogenic group in a part of the molecular structure. There may be. The polymer liquid crystal is characterized by high film forming productivity because it can be cooled from the liquid crystal state to fix the molecular alignment state. Since the low-molecular liquid crystal is excellent in orientation, it has a feature that a highly transparent retardation layer is easily obtained.

  The rod-like liquid crystal compound preferably has at least one crosslinkable functional group in a part of the molecular structure. This is because the cross-linking reaction increases the mechanical strength and provides a retardation layer having excellent durability. Examples of the crosslinkable functional group include an acryloyl group, a methacryloyl group, an epoxy group, and a vinyl ether group. A commercially available rod-like liquid crystal compound can be used as it is. Alternatively, other liquid crystal compounds and arbitrary additives such as a polymerization initiator and a leveling agent may be added to a commercially available or synthesized rod-shaped liquid crystal compound to be used as a liquid crystalline composition. Examples of commercially available rod-shaped liquid crystal compounds having a crosslinkable functional group include BASF Corporation trade name “Pariocolor LC242” and HUNTSMAN Corporation trade name “CB483”.

Any appropriate alignment treatment method can be selected as a method for aligning the rod-like liquid crystal compound in a hybrid arrangement. In one embodiment, the first and second O plates may be manufactured by a manufacturing method including the following steps A _{1 to} E ₁ .

(A ₁ ) Step of preparing two substrates, performing a first alignment process on one substrate, and performing a second alignment process on the other substrate (however, the first alignment process and the second alignment process) Are not identical)
(B ₁ ) a step of adjusting a coating liquid containing a rod-like liquid crystal compound and a solvent,
(C ₁ ) a step of forming a laminate by sandwiching a coating liquid containing a rod-like liquid crystal compound and a solvent between the two substrates with the alignment-treated sides inside,
(D ₁₎ step of the laminate is heated to the liquid crystal temperature range,
(E ₁₎ a step of cooling below the liquid crystal temperature range a laminate.

  Here, the first and second alignment processes are independently a vertical alignment process, a horizontal alignment process, or a tilt alignment process.

As another embodiment, the first and second O plates may be manufactured by a manufacturing method including the following steps A _{2 to} E ₂ .

(A ₂ ) A step of performing an orientation treatment on the substrate,
(B ₂ ) a step of preparing a coating liquid containing a rod-like liquid crystal compound and a solvent,
(C ₂ ) a step of applying the coating liquid to the orientation-treated surface of the substrate to form a laminate,
(D ₂₎ above and the coating liquid substrate side in a state in which the interface on the side opposite the contact with the air, the step of heating the laminate to the liquid crystal temperature range,
(E ₂ ) A step of cooling the laminate to a liquid crystal temperature range or lower.

  Here, the alignment process is a vertical alignment process or a tilt alignment process. Which of these treatments is selected can be appropriately determined according to the type and chemical properties of the rod-shaped liquid crystal compound to be used.

In the liquid crystal panel of the present invention, the tilt angle (θ _P ) on the polarizer side of the rod-like liquid crystal compound and the tilt angle (θ _B ) on the liquid crystal panel side of the first and second O plates are, for example, the above step A Depending on the conditions of _{1 to} E ₁ or the steps A _{2 to} E ₂ , the rod-like liquid crystal compound, or the type of the composition containing the same, it can be increased or decreased as appropriate.

  An appropriate method can be appropriately employed as the alignment treatment method. The alignment treatment method includes, for example, (A) a method in which an alignment agent is adsorbed on the surface of a substrate to form an alignment agent layer (also referred to as an alignment film), and (B) the substrate or the substrate is formed. Examples include a method of changing the surface of the alignment film in shape, and (C) a method of irradiating light on the substrate or the surface of the alignment film formed on the substrate (also referred to as a photo-alignment method). Among these, the alignment method is preferably a photo-alignment method. Since the photo-alignment method is a process in which generation of static electricity, dust, dust, and the like is extremely small, a retardation layer with excellent quality can be manufactured. Further, the tilt angle of the rod-like liquid crystal compound in the retardation layer and the in-plane direction in the slow axis direction can be arbitrarily controlled by the direction and orientation of light irradiation.

  The alignment agent for the vertical alignment treatment is not particularly limited, and for example, lecithin, versamide 100, octadecylmalonic acid, organic silane, tetrafluoroethylene, polyimide, stearic acid, and the like can be used. The alignment agent for the horizontal alignment treatment is not particularly limited. For example, carbon, polyoxyethylene, versamide 125, polyvinyl alcohol, polyimide, dibasic carboxylic acid chromium complex, organosilane, acetylene, dibasic fatty acid. , Crown ethers and the like can be used.

  The alignment agent for the photo-alignment method (the formed film is also referred to as a photo-alignment film) preferably contains a compound having at least one photoreactive functional group in the molecular structure. Such alignment agents include, for example, those containing a compound having a photoreactive functional group that causes a photochemical reaction such as a photoisomerization reaction, a photo-ring-opening reaction, a photo-dimerization reaction, a photo-decomposition reaction, or a photo-fleece transition reaction. It is done. Examples of the photoreactive functional group that causes a photoisomerization reaction include an azobenzene group, a stilbene group, an α-hydrazono-β-ketoester group, a cinnamate group, a benzylidenephthalimidine group, and retinoic acid. Examples of the photoreactive functional group that causes a photodimerization reaction include a cinnamate group, a benzylidenephthalimidine group, a chalcone group, a coumarin group, a stilpyridine group, and an anthracene group.

The conditions for irradiating the surface of the alignment film with light are as follows. The conditions for irradiating the surface of the photo-alignment film are appropriately determined according to the type of photochemical reaction of the compound having a photoreactive functional group used in the photo-alignment film. An appropriate method can be selected. Examples of the light source used for light irradiation include an ultra-high pressure mercury lamp, a flash UV lamp, a high pressure mercury lamp, a low pressure mercury lamp, a deep UV lamp, a xenon lamp, and a metal hydride lamp. The wavelength of the light source is preferably 210 nm to 380 nm. Furthermore, the value of the light irradiation amount measured at a wavelength of 365 nm is preferably 5 mJ / cm ^{2 to} 500 mJ / cm ² . The wavelength of the light source is preferably used by cutting a region of 100 nm to 200 nm with a filter or the like in order to suppress the photodecomposition reaction of the photo-alignment film. If it is the said conditions, a rod-shaped liquid crystal compound can be uniformly aligned in a hybrid arrangement.

  Any appropriate method can be adopted as a method of adjusting the coating liquid containing the rod-like liquid crystal compound and the solvent. Here, the “coating liquid” represents a solution or a dispersion. Examples of the solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pentanone, 2-hexanone, diethyl ether, tetrahydrofuran, dioxane, anisole, ethyl acetate, butyl acetate, toluene, xylene, chloroform, and dichloromethane. Dichloroethane, dimethylformamide, dimethylacetamide, methyl cellosolve and the like. These solvents can be used alone or in admixture of two or more. The concentration of the rod-like liquid crystal compound is preferably 5% by weight to 40% by weight.

  As a method of applying the coating liquid containing the rod-like liquid crystal compound and the solvent, a coating method using an appropriate coater can be adopted as appropriate. Examples of the coater include a reverse roll coater, a forward rotation roll coater, a gravure coater, a knife coater, a rod coater, a slot die coater, a slot orifice coater, a curtain coater, a fountain coater, an air doctor coater, a kiss coater, a dip coater, a bead coater, and a blade coater. Cast coater, spray coater, spin coater, extrusion coater, hot melt coater and the like. The coater is preferably a reverse roll coater, a forward rotation roll coater, a gravure coater, a rod coater, a slot die coater, a slot orifice coater, a curtain coater, and a fountain coater. The coater preferably uses a coater head using a closed applicator in order to prevent a change in the concentration of the coating liquid. With the coating method using the above coater, a solidified layer with small thickness variation can be obtained.

Any appropriate method can be adopted as a method of forming the solidified layer of the rod-like liquid crystal compound aligned in the hybrid arrangement. Examples of the method for forming the solidified layer include a method including the steps A _{1 to} E ₁ and a method including the steps A _{2 to} E ₂ . The drying temperature is preferably 30 ° C. or higher and a liquid crystal phase-isotropic phase transition temperature (Ti) or lower, and more preferably 30 ° C. to 120 ° C. Examples of the heating and drying means include an air circulation drying oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature control, a heat pipe roll, or a metal belt. The heating method and temperature control method used are mentioned. The time for drying by heating (drying time) is usually from 1 minute to 20 minutes. The isotropic phase transition temperature (Ti) is determined by observing the rod-like liquid crystal compound or a sample of the liquid crystal composition containing the same or the sample of the disk-like liquid crystal compound or the liquid crystal composition containing the same with a polarizing microscope. Can be obtained.

  Any appropriate method may be selected as a method for forming the cured layer of the rod-shaped liquid crystal compound aligned in the hybrid arrangement. Preferably, the cured layer is formed by using a rod-like liquid crystal compound (also referred to as a cross-linkable rod-like liquid crystal compound) having at least one crosslinkable functional group in a part of the molecular structure, and irradiating it with ultraviolet rays. This is a method of photocrosslinking. In this case, it is preferable that the time of irradiating the ultraviolet rays is after the solidified layer is formed or during the process of solidification.

As the conditions for curing the rod-like liquid crystal compound, any appropriate method can be selected according to the type of photochemical reaction of the crosslinkable rod-like liquid crystal compound or the crosslinkable composition. As a light source used for light irradiation, it can select suitably from what was illustrated for the said photo-alignment method. The wavelength of the light source is preferably 210 nm to 380 nm. Furthermore, the value of the light irradiation amount measured at a wavelength of 310 nm is preferably 30 mJ / cm ^{2 to} 1000 mJ / cm ² . In order to suppress the photodecomposition reaction of the photo-alignment film or the rod-like liquid crystal compound, the wavelength of the light source is preferably used by cutting a region of 100 nm to 200 nm with a filter or the like. Furthermore, it is preferable to replace the atmosphere around the crosslinkable rod-like liquid crystal compound or the crosslinkable composition irradiated with light with an inert gas such as nitrogen. If it is said conditions, the hardened layer excellent in thickness uniformity can be formed.

  In another embodiment, the first and second O plates are formed from a solidified layer or a hardened layer of a disk-like liquid crystal compound aligned in a hybrid arrangement.

  The disk-shaped liquid crystal compound is usually a molecule in which 2 to 8 side chains are bonded radially to the disk-shaped central core through ether bonds or ester bonds. As the above-mentioned core, “Liquid Crystal Dictionary” (1989) p. 22 Examples thereof include benzene, triphenylene, turxene, pyran, lupigarol, porphyrin, metal complex and the like as described in FIG. The discotic compound is preferably a triphenylene-based discotic compound having triphenylene as a central core, and more preferably a liquid crystal compound represented by the following general formula (I).

  In the general formula (I), n is an integer of 2 to 10. N is preferably 4 to 8, particularly preferably 4 to 6, and most preferably 6.

  Any appropriate alignment treatment method can be adopted as a method of tilting and aligning the liquid crystalline composition containing the discotic compound. Examples of the alignment treatment method include an oblique vapor deposition method, a photo alignment method, and a rubbing method. The oblique deposition method is typically a method in which an oxide such as silicon oxide is deposited from an oblique direction with respect to a substrate. In this method, the tilt angle of the liquid crystal molecules can be appropriately increased or decreased by selecting the vapor deposition angle, the number of vapor depositions, and the like. The above photo-alignment method is described in, for example, CMC Publishing “Functional Materials” Vol. 25 No. 12 (2005) p. 15-P. 21 is a method in which a photoreactive alignment film formed on a substrate surface is irradiated with polarized light or non-polarized light from an oblique direction. In this method, the tilt angle of the liquid crystal molecules can be appropriately increased or decreased by selecting the irradiation angle and the irradiation time for polarized or non-polarized light. The rubbing method is a method in which the substrate or the alignment film surface is rubbed in one direction with cotton cloth, nylon, rayon or the like.

Any appropriate method may be adopted as a method of solidifying or curing the liquid crystalline composition containing the discotic compound that is tilted and aligned. The solidified layer of the liquid crystalline composition containing the discotic compound subjected to the tilt alignment can be obtained, for example, by a method including the following step A ₃ to step C ₃ .

(A ₃ ) a step of subjecting the surface of the substrate (also referred to as a support) to orientation treatment,
(B ₃ ) a step of applying a liquid crystal composition solution or dispersion on the surface of the substrate that has been subjected to the alignment treatment, and aligning,
(C ₃ ) A step of drying the liquid crystalline composition to form a solidified layer.

Cured layer of a liquid crystal composition containing a discotic compound is the tilt, in addition to the above Step A ₃ -C _3, can be obtained by a process further comprising the following steps D _3.

(D ₃₎ in the solidified layer obtained in step C _3, it was irradiated with ultraviolet light, curing the liquid crystal composition.

  In addition, when obtaining a hardened layer, it is preferable to make a discotic compound into a photocrosslinkable thing, or to add a photocrosslinkable compound to the said liquid crystalline composition.

  Regarding the calculation method of the tilt angle of the discotic liquid crystal compound, the alignment treatment method, and the adjustment of the coating liquid, the same procedure as the alignment treatment method of the rod-like liquid crystal compound and the adjustment of the coating liquid is used. The alignment treatment of the compound and the adjustment of the coating solution can be performed.

A direction (also referred to as an alignment direction) in which the optical axis directions of the first and second plates are projected onto the liquid crystal cell surface is preferably substantially the same as the alignment processing direction of the liquid crystal cell. In the present specification, the “optical axis direction” means a statistical orientation of the entire liquid crystal molecule, and the O plate is formed of a liquid crystal compound that is uniformly aligned in the thickness direction (that is, the O plate). The optical axis in the direction of the optical axis, and the O-plate is formed of a liquid crystal compound that is non-uniformly oriented in the thickness direction (for example, hybrid alignment) If no axis is present), it represents the direction of the average tilt angle. The “optical axis direction” is also referred to as an average inclination angle (θ _ave. = (Θ _P + θ _B ) / 2). Here, the θ _ave. Is substantially parallel to the slow axis of the O plate in the biaxial orientation direction.

The average inclination angle (θ _ave. ) Is preferably 10 ° to 45 °, more preferably 15 ° to 42 °, and particularly preferably 20 ° to 40 °. By setting the average tilt angle in the above range, more appropriate optical compensation is performed, and a liquid crystal display device having a high contrast ratio in an oblique direction can be obtained.

  The slow axis of the first O plate is substantially parallel to the absorption axis of the first polarizing plate, and the slow axis of the second O plate is an absorption axis of the second polarizing plate. And substantially parallel. In the present specification, the “slow axis” refers to the direction in which the in-plane refractive index becomes the maximum value. “Substantially parallel” includes a case where an angle formed by two optical axes is 0 ° ± 1 °, and preferably 0 ° ± 0.5 °. By arranging in such an axial relationship, more appropriate optical compensation of the liquid crystal cell is performed, and a liquid crystal display device having a high contrast ratio in an oblique direction can be obtained.

  The transmittance (T [590]) at a wavelength of 590 nm of the first O plate and / or the second O plate is preferably 85% or more, and more preferably 90% or more.

  The in-plane retardation value (Re [590]) at a wavelength of 590 nm of the first O plate and / or the second O plate is a black display (voltage) when the liquid crystal display device is a normally white system. An appropriate value is appropriately set so as to be substantially equal to the phase difference value of the liquid crystal cell at the time of application. The Re [590] of the first O plate and / or the second O plate is preferably 50 nm to 200 nm, more preferably 70 nm to 180 nm, and particularly preferably 90 nm to 160 nm. By setting the in-plane retardation value within the above range, more appropriate optical compensation is performed, and a liquid crystal display device having a high contrast ratio in an oblique direction can be obtained. In this specification, the in-plane retardation value (Re [λ]) refers to an in-plane retardation value at a wavelength λ (nm) at 23 ° C. Re [λ] can be obtained by Re [λ] = (nx−ny) × d, where d (nm) is the thickness of the film.

<E. Biaxial retardation layer>
When the O plate is formed from a solidified layer or a hardened layer of a rod-like liquid crystal compound aligned in a hybrid arrangement, the liquid crystal panel of the present invention preferably includes the liquid crystal cell and the first O plate. A first biaxial retardation layer is further provided therebetween, and a second biaxial retardation layer is further provided between the liquid crystal cell and the second O plate.

  In this specification, the “biaxial retardation layer” means that the refractive index ellipsoid satisfies the relationship of nx> ny> nz. Here, nx is the refractive index in the slow axis direction, ny is the in-plane refractive index direction (also referred to as the fast axis direction), and nz is the refractive index in the thickness direction. Such a biaxial retardation layer satisfies 10 nm <Re [590] <Rth [590].

  The first biaxial retardation layer and the second biaxial retardation layer may be the same as or different from each other. The first and second biaxial retardation layers may be single-layer or multilayer retardation layers, or may be a laminate including a substrate and a retardation layer. Alternatively, the biaxial retardation layer may also serve as the O plate substrate described above. When the biaxial retardation layer also serves as a base material for the O plate, one surface of the biaxial retardation layer may be subjected to an alignment treatment in order to align the rod-like liquid crystal compound. Or may have an alignment film. The thickness of the first and second biaxial retardation layers is usually 0.5 μm to 100 μm, preferably 0.5 μm to 50 μm.

  Referring to FIG. 1, the first biaxial retardation layer 41 is disposed between the first O plate 31 and the first substrate 11, and the second biaxial retardation layer 42 includes the first biaxial retardation layer 42. The second O plate 32 and the second substrate 12 are disposed.

  A preferred embodiment of the first and second biaxial retardation layers will be described with reference to FIG. The slow axis 5 of the first biaxial retardation layer 41 is substantially orthogonal to the absorption axis 3 of the first polarizing plate 21, and the slow axis 6 of the second biaxial retardation layer 42. Is substantially orthogonal to the absorption axis 4 of the second polarizing plate 22. The slow axis 5 of the first biaxial retardation layer 41 is substantially orthogonal to the slow axis 6 of the second biaxial retardation layer 42. The slow axis 5 of the first biaxial retardation layer 41 is substantially the same as the rubbing direction 1 of the first substrate 11, and the slow axis of the second biaxial retardation layer 42 is the first axis. 2 is substantially orthogonal to the rubbing direction 2 of the substrate 12. By arranging in such an axial relationship, more appropriate optical compensation of the liquid crystal cell is performed, and a liquid crystal display device having a high contrast ratio in an oblique direction can be obtained.

  The transmittance (T [590]) at a wavelength of 590 nm of the first biaxial retardation layer and / or the second biaxial retardation layer is preferably 85% or more, more preferably 90%. That's it.

  The in-plane retardation value (Re [590]) at a wavelength of 590 nm of the first biaxial retardation layer and / or the second biaxial retardation layer is preferably 50 nm to 200 nm. Preferably they are 80 nm-180 nm, Most preferably, they are 100 nm-160 nm.

The difference (Re [590] _O1 −Re [590] _O1 ) between Re [590] _{B1 of} the first biaxial retardation layer and Re [590] _O1 of the first O plate is preferably It is 0 nm-60 nm, More preferably, it is 10 nm-50 nm. And Re [590] _B2 of the second biaxial retardation layer, the difference between Re [590] _O2 of the second O plate _{(Re [590] B2 -Re [} 590] O2) is preferably It is 0 nm-60 nm, More preferably, it is 10 nm-50 nm. By setting the in-plane retardation value within the above range, more appropriate optical compensation of the liquid crystal cell is performed, and a liquid crystal display device having a high contrast ratio in an oblique direction can be obtained.

  The retardation value (Rth [590]) in the thickness direction when the wavelength of the first biaxial retardation layer and / or the second biaxial retardation layer is 590 nm is such that the refractive index ellipsoid is nx> ny. > In the range satisfying the relationship of> nz, preferably 80 nm to 360 nm, more preferably 100 nm to 320 nm, and particularly preferably 120 nm to 280 nm. In the present specification, the thickness direction retardation value (Rth [λ]) refers to the thickness direction retardation value at 23 ° C. and the wavelength λ (nm). Rth [λ] can be obtained by Rth [λ] = (nx−nz) × d, where d (nm) is the thickness of the film. By setting the retardation value in the thickness direction within the above range, more appropriate optical compensation of the liquid crystal cell is performed, more appropriate optical compensation of the liquid crystal cell is performed, and a liquid crystal display device having a high contrast ratio in the oblique direction is provided. Obtainable.

  The Nz coefficient of the first biaxial retardation layer and / or the second biaxial retardation layer is preferably 1.1 to 6.0. More preferably, it is 1.1-4.0, Most preferably, it is 1.2-2.0. The Nz coefficient is obtained by the equation: Rth [590] / Re [590]. By setting the Nz coefficient in the above range, a more appropriate liquid crystal cell is optically compensated, and a liquid crystal display device having a high contrast ratio in the front direction can be obtained.

  As a material for forming the first and / or second biaxial retardation layer, any appropriate material can be selected as long as it satisfies the optical characteristics described above. Preferably, the first and / or second biaxial retardation layer includes a retardation film containing a thermoplastic resin. The thermoplastic resin is not particularly limited. For example, norbornene resin, cellulose resin, polyamide resin, polycarbonate resin, polysulfone resin, polyethersulfone resin, polyetherketone resin, polyarylate resin, polyamideimide resin, A polyimide resin etc. are mentioned. Said thermoplastic resin is used individually or in combination of 2 or more types.

  Preferably, the first and / or second biaxial retardation layer includes a retardation film containing a norbornene resin. In this specification, the “norbornene” resin refers to a (co) polymer obtained by using a norbornene-based monomer having a norbornene ring as a part or all of a starting material (monomer). The “(co) polymer” represents a homopolymer or a copolymer (copolymer). The retardation film is usually produced by stretching a polymer film formed into a sheet shape.

  As the polymer film containing the norbornene resin, a commercially available film can be used as it is. Alternatively, a commercially available film subjected to secondary processing such as stretching and / or shrinking can be used. As a polymer film containing a commercially available norbornene resin, for example, Arton series (trade name; ARTON F, ARTON FX, ARTON D) manufactured by JSR Corporation, or ZEONOR series (trade name; ZEONOR Corporation) manufactured by Optes Co., Ltd. ZF14, ZEONOR ZF16) and the like.

As a method of stretching the polymer film, any appropriate stretching method can be adopted depending on the purpose. Examples of the stretching method include a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, and a longitudinal and transverse sequential stretching method. As a means for stretching the polymer film, any suitable stretching machine such as a roll stretching machine, a tenter stretching machine, and a biaxial stretching machine can be used. Preferably, the stretching machine includes a temperature control unit. When extending | stretching by heating, the internal temperature of a extending | stretching machine may be changed continuously and may be changed in steps. The stretching step may be performed once or divided into two or more times. The stretching direction may be the longitudinal direction (MD direction) of the film or the width direction (TD direction). Moreover, you may extend in the diagonal direction (diagonal extending | stretching) using the extending | stretching method of FIG. 1 of Unexamined-Japanese-Patent No. 2003-262721.

  The stretching temperature (stretching temperature) of the polymer film can be appropriately set according to the purpose. Preferably, the stretching is performed in the range of Tg + 1 ° C. to Tg + 30 ° C. with respect to the glass transition temperature (Tg) of the polymer film. By selecting such conditions, the retardation value is likely to be uniform, and the retardation film is difficult to crystallize. The stretching temperature is preferably 100 ° C to 180 ° C, more preferably 120 ° C to 160 ° C. As the stretching temperature control means, for example, an air circulation type constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature adjustment, a heat pipe roll, a metal belt, etc. Can be mentioned. The glass transition temperature can be determined by a DSC method according to JIS K 7121-1987.

  The magnification (stretch ratio) for stretching the polymer film can be appropriately selected according to the target retardation layer. The draw ratio is preferably more than 1 and 3 times or less, more preferably more than 1 and 2.5 times or less, and particularly preferably 1.1 times to 2.0 times. Moreover, the feeding speed at the time of stretching is not particularly limited, but is preferably 0.5 m / min to 30 m / min in view of mechanical accuracy, stability and the like. If it is said extending | stretching conditions, not only the target phase difference layer can be obtained but the phase difference film excellent in uniformity can be obtained.

<F. Liquid crystal display>
The liquid crystal display device of the present invention includes the liquid crystal panel. FIG. 3 is a schematic cross-sectional view of a liquid phase display device according to a preferred embodiment of the present invention. It should be noted that for the sake of easy understanding, the ratio of the vertical, horizontal, and thickness of each component shown in FIG. 3 is different from the actual one. The liquid crystal display device 200 includes at least a liquid crystal panel 100 and a backlight unit 80 disposed on one side of the liquid crystal panel 100. In the illustrated example, a case where a direct system is adopted as the backlight unit is shown, but this is, for example, a sidelight system.

  When the direct type is employed, the backlight unit 80 preferably includes at least a light source 81, a reflection film 82, a diffusion plate 83, a prism sheet 84, and a brightness enhancement film 85. In addition, as long as the effect of the present invention is obtained, a part of the optical agent illustrated in FIG. 3 can be omitted depending on the application, such as an illumination method of a liquid crystal display device and a driving mode of a liquid crystal cell, or , Other optical components can be substituted.

  The liquid crystal display device may be a transmissive type that irradiates light from the back side of the liquid crystal panel to view the screen, or a reflective type that irradiates light from the viewing side of the liquid crystal panel to view the screen. good. Alternatively, the liquid crystal display device may be a transflective type having both transmissive and reflective properties.

  In the liquid crystal display device of the present invention, the average value of the contrast ratio at a polar angle of 40 ° and an azimuth angle of 0 ° to 360 ° is preferably 60 or more, and more preferably 70 to 150. Further, in the liquid crystal display device, the maximum value of the contrast ratio at a polar angle of 40 ° and an azimuth angle of 0 ° to 360 ° is preferably 160 or more, and more preferably 170 to 250. Further, in the liquid crystal display device, the minimum value of the contrast ratio at a polar angle of 40 ° and an azimuth angle of 0 ° to 360 ° is preferably 20 or more, and more preferably 25 to 55. The liquid crystal display device of the present invention exhibits display characteristics that are thus far superior to conventional liquid crystal display devices.

<G. Application>
The liquid crystal display device of the present invention is used for any appropriate application. Applications include, for example, personal computer monitors, notebook computers, copiers and other office automation equipment, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable devices such as band game machines, video cameras, televisions, microwave ovens, etc. Home appliances, back monitors, car navigation system monitors, car audio and other in-vehicle devices, commercial store information monitors and other nursing care / medical devices.

  Preferably, the use of the liquid crystal display device of the present invention is a television. The screen size of the television is preferably a wide 17 type (373 mm × 224 mm) or more, more preferably a wide type 23 type (499 mm × 300 mm) or more, and particularly preferably a wide type (687 mm × 412 mm) or more. .

The present invention will be further described using the above examples and comparative examples. In addition, this invention is not limited only to these Examples. In addition, each analysis method used in the Example is as follows.
(1) Measuring method of tilt angle of interface of rod-like liquid crystal compound:
Journal of Applied Phisics Vol. 38 (1999) p. The expression of Witte according to 748, n _e, n _o, and in parallel with the phase difference value (the slow axis, in 5 ° increments in the polar angle -40 ° ~ + 40 ° (the normal direction to 0 °) Each measured value) was substituted and determined. The phase difference value was a value measured at a wavelength of 590 nm and 23 ° C. using a spectroscopic ellipsometer [manufactured by JASCO Corporation, product name “M-220”]. Further, n _e, n _o was used a value measured using an Abbe refractometer Atago Co., Ltd. product name "DR-M4".
(2) Measurement of single transmittance of polarizer:
Using a spectrophotometer [product name “DOT-3” manufactured by Murakami Color Research Laboratory Co., Ltd.], the Y value is corrected for visibility with a 2 degree field of view (C light source) of JIS Z 8701-1982. did.
(3) Measurement of polarization degree of polarizer:
Using a spectrophotometer [product name “DOT-3” manufactured by Murakami Color Research Laboratory Co., Ltd.], the parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ) of the polarizer are measured. Degree (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100. The average parallel transmittance (H ₀ ) is a transmittance value of a parallel laminated polarizer produced by superposing two polarizers of the same type so that their absorption axes are parallel to each other. The orthogonal transmittance (H ₉₀ ) is a value of the transmittance of an orthogonal laminated polarizer produced by superposing two polarizers of the same type so that their absorption axes are orthogonal to each other. In addition, these transmittance | permeability is Y value which performed visibility correction | amendment by the 2nd visual field (C light source) of JISZ8701 (1982).
(4) Measuring method of phase difference value (Re [λ], Rth [λ]), Nz coefficient, T [590]:
Measurement was performed at 23 ° C. using a trade name “KOBRA21-ADH” manufactured by Oji Scientific Instruments. In addition, the value measured using the Abbe refractometer [Atago Co., Ltd. product name "DR-M4"] was used for the average refractive index.
(5) Thickness measurement method:
When the thickness was less than 10 μm, measurement was performed using a thin film spectrophotometer [manufactured by Otsuka Electronics Co., Ltd., “instant multiphotometry system MCPD-2000”]. When the thickness was 10 μm or more, measurement was performed using an Anritsu digital micrometer “KC-351C type”.
(6) Measuring method of glass transition temperature (Tg):
Using a differential scanning calorimeter [Seiko Co., Ltd. product name “DSC-6200”], it was determined by a method according to JIS K 7121 (1987) (measurement method of plastic transition temperature). Specifically, a sample of 3 mg was heated (heating rate: 10 ° C./min) in a nitrogen atmosphere (gas flow rate: 80 ml / min), measured twice, and the second data was adopted. The calorimeter corrected the temperature using a standard material (indium).
(7) Contrast ratio measurement method:
After 30 minutes have passed since the backlight was turned on in a dark room at 23 ° C., the Y value of the XYZ display system when a white image and a black image were displayed was measured using a product name “EZ Contrast 160D” manufactured by ELDIM. . The contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) in the white image and the Y value (YB) in the black image. The long side of the liquid crystal panel was set to an azimuth angle of 0 °, and the normal direction was set to a polar angle of 0 °.

[Preparation of liquid crystal cell]
[Reference Example 1]
Remove all optical films placed above and below the liquid crystal cell from the liquid crystal display device [17 type liquid crystal monitor (model number: FP71 +) manufactured by BENQ Co., Ltd.] including the TN mode liquid crystal cell. (Front and back) was washed. The liquid crystal cell thus fabricated includes a liquid crystal layer, a first substrate disposed on the first polarizing plate side of the liquid crystal layer, and a second substrate disposed on the second polarizing plate side of the liquid crystal layer. Each of the first substrate and the second substrate has an alignment film that is aligned on the liquid crystal layer side, and the liquid crystal layer has an electric field The liquid crystal cell A was aligned in a twisted arrangement in the absence.

[Preparation of first and second polarizing plates]
[Reference Example 2]
Commercially available polarizing plates [Nitto Denko Corporation trade name “SEG1423DU”] and [Nitto Denko Corporation trade name “SEG1224DU”] were used as they were. These polarizing plates include a protective layer mainly composed of triacetyl cellulose on both sides of a polarizer mainly composed of a polyvinyl alcohol-based resin containing iodine. The single transmittance of “SEG1423DU” was 42.4%, and the degree of polarization was 99.99%. The single transmittance of “SEG1224DU” was 43.2%, and the degree of polarization was 99.99%. In this embodiment, “SEG1423DU” is used for the first polarizing plate and “SEG1224DU” is used for the second polarizing plate, which are referred to as polarizing plate A and polarizing plate B, respectively.

[Production of first and second O plates]
[Reference Example 3]
Spin coater with an aligning agent [trade name “ROF103” manufactured by Rolic Co., Ltd.] for photo-alignment film on the surface of a polymer film [manufactured by Nitto Denko Co., Ltd.] having a thickness of 80 μm and hard-coded triacetyl cellulose as a main component (Condition: 3000 rpm for 1 minute) and dried in a 100 ° C. air circulation type constant temperature oven for 10 minutes to form a photo-alignment film having a thickness of 70 nm. Next, this photo-alignment film was irradiated with polarized ultraviolet rays (irradiation amount: 100 mJ / cm ² ) from an oblique direction of 140 ° with respect to the substrate plane, and subjected to a tilt alignment process. Next, a liquid crystalline composition containing a rod-shaped liquid crystal compound having two crosslinkable functional groups in the molecular structure and a polymerization initiator [trade name “ROP5101” (liquid crystal temperature range of 30 ° C. to 57 ° C.) manufactured by Rolic Co., Ltd.] And a coating liquid (concentration: 20% by weight) containing cyclopentanone. Next, this coating liquid is applied to the surface of the photo-alignment film, and the interface of the coating liquid opposite to the substrate is brought into contact with air, heated to 50 ° C., and 2 ° C. at that temperature. The solidified layer of the rod-like liquid crystal compound that was held for a minute and aligned in a hybrid arrangement was formed. Further, the solidified layer was irradiated with ultraviolet rays (irradiation amount: 500 mJ / cm ² : at 365 nm) in a nitrogen atmosphere to form a cured layer having a thickness of 1.1 μm on the substrate. The cured layer had T [590] = 90%, Re [590] = 110 nm, the tilt angle (θ _air ) = 0 ° of the _air interface, and the tilt angle (θ _AL ) = 70 ° of the substrate interface. In the present embodiment, the first O plate and the second O plate having the same characteristics are used as a hardened layer A and a hardened layer B, respectively.

[Production of first and second biaxial retardation layers]
[Reference Example 4]
A polymer film including a norbornene-based resin having a thickness of 100 μm [trade name “Zeonor ZF14” (Tg = 136 ° C.) manufactured by Optes Co., Ltd.] is fixed at 150 ° C. by a fixed end lateral uniaxial stretching method using a tenter stretching machine. The film was stretched 2.56 times in the width direction of the film. The obtained retardation film had transmittance = 92%, Re [590] = 120 nm, Rth [590] = 180 nm, and Nz coefficient = 1.5. In this embodiment, the first biaxial retardation layer and the second biaxial retardation layer having the same characteristics are used as the retardation film A and the retardation film B, respectively.

[Production of liquid crystal panel and liquid crystal display device]
[Example 1]
As the first biaxial retardation layer on the viewing side surface of the liquid crystal cell A obtained in Reference Example 1, the angle formed between the slow axis and the long side direction of the liquid crystal cell is as follows. It laminated | stacked through the acrylic adhesive (thickness: 20 micrometers) so that it might become 135 degrees. Next, the base material is removed on the surface of the retardation film A as a first O plate so that the angle between the orientation direction of the cured layer A and the long side direction of the liquid crystal cell is 45 °. The film was transferred via an acrylic pressure-sensitive adhesive (thickness: 20 μm). Next, on the surface of the cured layer A, an acrylic pressure-sensitive adhesive (thickness: the thickness of the polarizing plate A is 45 ° so that the angle between the absorption axis and the long side of the liquid crystal cell is the first polarizing plate. 20 μm). At this time, the tilt angle (θ _P ) on the polarizer side of the rod-like liquid crystal compound in the cured layer A is 70 °, the tilt angle (θ _B ) of the biaxial retardation layer is 70 °, The tilt angle (θ _B ) of the axial retardation layer is 0 °. The alignment direction of the rod-like liquid crystal compound (the direction in which the optical axis is projected onto the liquid crystal cell surface) is substantially the same as the alignment treatment (rubbing) direction of the liquid crystal cell. The slow axis of the first O plate is substantially parallel to the absorption axis of the first polarizing plate. The slow axis of the first biaxial retardation layer is substantially orthogonal to the absorption axis of the first polarizing plate.

Subsequently, a retardation layer film B is formed as a second biaxial retardation layer on the backlight side surface of the liquid crystal cell A, and an angle formed between the slow axis and the long side direction of the liquid crystal cell is 45. The film was laminated with an acrylic pressure-sensitive adhesive (thickness: 20 μm) so that the temperature was 0 °. Next, as the second O plate on the surface of the retardation film B, the base material is removed so that the angle between the orientation direction of the cured layer B and the long side direction of the liquid crystal cell is 135 °. The film was transferred through an acrylic pressure-sensitive adhesive (thickness: 20 μm). Next, the tilt angle (θ _P ) on the polarizing plate side of the rod-like liquid crystal compound in the cured layer B is 70 °, and the tilt angle (θ _B ) on the biaxial retardation layer side is 0 °. Further, the alignment direction of the rod-like liquid crystal compound is substantially the same as the alignment treatment (rubbing) direction of the liquid crystal cell. The slow axis of the second O plate is practically parallel to the absorption axis of the second polarizing plate. The slow axis of the second biaxial retardation layer is substantially orthogonal to the absorption axis of the second polarizing plate. The absorption axis of the first polarizing plate is substantially perpendicular to the absorption axis of the second polarizing plate. In addition, the sticking angle of each component is a value obtained counterclockwise with the long side direction of the liquid crystal cell being 0 °.

  The liquid crystal panel A thus produced was combined with the backlight unit of the original liquid crystal display device to produce a liquid crystal display device A. FIG. 4 is a schematic diagram showing the optical axial relationship of each layer of the liquid layer panel A. The characteristics of the obtained liquid crystal display device A are shown in Table 1 below. The average value of the contrast ratio of the liquid crystal display device A at an azimuth angle of 0 ° to 360 ° and a polar angle of 40 ° was 110, the maximum value was 211, and the minimum value was 39.

[Comparative Example 1]
A liquid crystal panel B and a liquid crystal display device B were produced in the same manner as in Example 1 except that the polarizing plate A prepared in Reference Example 2 was used as the second polarizing plate. The characteristics of the obtained liquid crystal display device B are shown in Table 1 below.

  Liquid crystal panel C as in Example 1 except that the polarizing plate B prepared in Reference Example 1 was used as the first polarizing plate, and the polarizing plate A prepared in Reference Example 1 was used as the second polarizing plate. And the liquid crystal display device C was produced. The characteristics of the obtained liquid crystal display device C are shown in Table 1 below.

[Evaluation]
As shown in Example 1, in the liquid crystal display device including the liquid crystal panel of the present invention, the contrast ratio in the oblique direction is such that the transmittance (T ₂ ) of the _second polarizing plate is the transmittance (T ₂ ) of the first polarizing plate. _By making it larger than ₁ ), a contrast ratio in the front direction was significantly higher than that using a conventional liquid crystal panel. On the other hand, in the liquid crystal display devices of Comparative Examples 1 and 2, the transmittance (T ₂ ) of the second polarizing plate is smaller than the transmittance (T ₁ ) of the first polarizing plate. Only low direction contrast ratios were obtained.

  As described above, since the liquid crystal panel of the present invention exhibits a high contrast ratio in the front direction when used in a liquid crystal display device, it is extremely useful for improving the display characteristics of, for example, a personal computer monitor or a liquid crystal television.

It is a schematic sectional drawing of the liquid crystal panel of this invention. It is a schematic perspective view of the liquid crystal panel of FIG. It is a schematic diagram which shows the concept of the typical manufacturing process of the polarizer used for this invention. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. 3 is a schematic diagram illustrating an optical axial relationship of each layer of the liquid crystal panel of Example 1. FIG.

Explanation of symbols

1, 2 Alignment treatment (rubbing) direction 3, 4 Absorption axis 5, 6 Slow axis 7, 8 Optical axis direction 7 ', 8' Direction in which optical axis is projected on liquid crystal cell surface 10 Liquid crystal cell 11 First substrate 12 Second substrate 13 Liquid crystal layer 21 First polarizer 22 Second polarizer 31 First O plate 32 Second O plate 33 Rod-like liquid crystal compound 41 First biaxial retardation layer 42 Second two Axis retardation layer 80 Backlight unit 81 Light source 82 Reflective film 83 Diffuser plate 84 Prism sheet 85 Brightness enhancement film 100 Liquid crystal panel 200 Liquid crystal display device 301 Polyvinyl alcohol 300 Feeding part 310 Swelling bath 320 Dyeing baths 311, 312, 321, 322 331, 332, 341, 342 Roll 330 First crosslinking bath 340 Second dyeing bath 350 Washing bath 360 Drying means 370 Polarizer 380 winding Take part

Claims (14)

A liquid crystal cell;
A first polarizing plate disposed on the viewing side of the liquid crystal cell;
A second polarizing plate disposed on the backlight side of the liquid crystal cell;
A first O plate disposed between the liquid crystal cell and the first polarizing plate;
At least a second O-plate disposed between the liquid crystal cell and the second polarizing plate;
The transmittance (T ₂ ) of the _second polarizing plate is a liquid crystal panel that is larger than the transmittance (T ₁ ) of the first polarizing plate. The difference (ΔT = T ₂ −T ₁ ) between the transmittance (T ₂ ) of the _second polarizing plate and the transmittance (T ₁ ) of the first polarizing plate is 0.1% to 6.0. The liquid crystal panel according to claim 1, which is%. The liquid crystal cell includes a liquid crystal layer, a first substrate disposed on the liquid crystal layer on the first polarizing plate side, and a second substrate disposed on the liquid crystal layer on the second polarizing plate side. Including
3. The liquid crystal panel according to claim 1, wherein each of the first substrate and the second substrate has an alignment film subjected to alignment treatment on the liquid crystal layer side.   The liquid crystal panel according to claim 3, wherein the liquid crystal layer is oriented in a twisted arrangement in the absence of an electric field. 5. The liquid crystal panel according to claim 1, wherein the transmittance (T ₁ ) of the first polarizing plate is 38.3% to 43.3%. The liquid crystal panel according to claim 1, wherein a transmittance (T ₂ ) of the second polarizing plate is 41.1% to 44.3%.   The liquid crystal panel according to any one of claims 1 to 6, wherein a degree of polarization of the first polarizing plate and / or the second polarizing plate is 99% or more. The first polarizing plate and the second polarizing plate each include a first polarizer and a second polarizer,
The liquid crystal panel according to claim 1, wherein each of the first polarizer and the second polarizer has a polyvinyl alcohol resin containing iodine as a main component.   9. The liquid crystal panel according to claim 1, wherein the first and second O plates are formed of a solidified layer or a hardened layer of a rod-like liquid crystal compound aligned in a hybrid arrangement.   9. The liquid crystal panel according to claim 1, wherein the first and second O plates are formed from a solidified layer or a hardened layer of a disk-like liquid crystal compound aligned in a hybrid arrangement.   11. The liquid crystal panel according to claim 1, wherein a direction in which an optical axis direction of each of the first and second O plates is projected onto the liquid crystal cell surface is substantially the same as an alignment processing direction of the liquid crystal cell. .   The slow axis of the first O plate is substantially parallel to the absorption axis of the first polarizing plate, and the slow axis of the second O plate is the absorption axis of the second polarizing plate. The liquid crystal panel according to claim 1, which is substantially parallel to the liquid crystal panel. A first biaxial retardation layer between the liquid crystal cell and the first O plate;
The liquid crystal panel according to claim 1, further comprising a second biaxial retardation layer between the liquid crystal cell and the second O plate. A liquid crystal display device comprising the liquid crystal panel according to claim 1.