WO2014157181A1

WO2014157181A1 - Laminated polarizing plate for horizontal alignment liquid crystal display device and horizontal alignment liquid crystal display device

Info

Publication number: WO2014157181A1
Application number: PCT/JP2014/058243
Authority: WO
Inventors: 上坂　哲也; 涼西村; 浩今福
Original assignee: Ｊｘ日鉱日石エネルギー株式会社
Priority date: 2013-03-28
Filing date: 2014-03-25
Publication date: 2014-10-02
Also published as: JP2016106240A; TW201447398A

Abstract

Provided is a laminated polarizing plate that is for a horizontal alignment liquid crystal display device, has superior field of view characteristics, results from laminating, in the given order, at least a first polarizing plate, a first optically anisotropic layer, and a second optically anisotropic layer, and is characterized by the first optically anisotropic layer and the second optically anisotropic layer satisfying the following [1]: -60 nm ≤ Rth1 + Rth2 ≤ 60 nm (where Rth1 is the retardation value in the thickness direction of the first optically anisotropic film, and Rth2 is the retardation value in the thickness direction of the second optically anisotropic film).

Description

Laminated polarizing plate for horizontal alignment type liquid crystal display device and horizontal alignment type liquid crystal display device

The present invention relates to a laminated polarizing plate for a horizontal alignment type liquid crystal display device and a horizontal alignment type liquid crystal display device excellent in viewing angle characteristics.

As one of display modes in a liquid crystal display device, there is a horizontal alignment mode in which liquid crystal molecules in a liquid crystal cell are aligned in parallel with a substrate surface in an initial state (Patent Document 1). When no voltage is applied, liquid crystal molecules are arranged in parallel to the substrate surface, and a black display can be obtained by arranging linearly polarizing plates orthogonally on both sides of the liquid crystal cell.
When a voltage is applied, the liquid crystal molecules rotate from the direction parallel to the substrate surface to the direction of the electric field, and as a result, a bright display is obtained.
In black display of a horizontal alignment type liquid crystal display device, good black display can be obtained in the front visual field, but there is a problem that light leakage occurs in the oblique visual field and the contrast becomes low.

US Pat. No. 3,807,831

An object of the present invention is to provide a laminated polarizing plate for a horizontal alignment type liquid crystal display device and a horizontal alignment type liquid crystal display device having excellent viewing angle characteristics.

As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the following laminated polarizing plate for a horizontal alignment type liquid crystal display device and a horizontal alignment type liquid crystal display device using the same. The inventor has completed the present invention.
That is, the present invention is as follows.

[1] A laminated polarizing plate for a horizontal alignment type liquid crystal display device in which at least a first polarizing plate, a first optically anisotropic layer, and a second optically anisotropic layer are laminated in this order. A laminated polarizing plate for a horizontal alignment type liquid crystal display device, wherein the optically anisotropic layer and the second optically anisotropic layer satisfy the following [1].
[1] -60 nm ≦ Rth1 + Rth2 ≦ 60 nm
(Here, Rth1 means a retardation value in the thickness direction of the first optically anisotropic layer. Rth1 is Rth1 = {(nx1 + ny1) / 2−nz1} × d1 [nm]). d1 is the thickness of the first optically anisotropic layer, nx1 and ny1 are the main refractive index in the first optically anisotropic layer surface for light having a wavelength of 550 nm, nx1 is the maximum main refractive index in the surface, ny1 represents the main refractive index in the direction orthogonal to nx1, nz1 is the main refractive index in the thickness direction for light having a wavelength of 550 nm, and Rth2 is the retardation in the thickness direction of the second optical anisotropic layer. Rth2 is Rth2 = [{nx2 + ny2} / 2−nz2] × d2 [nm], where d2 is the thickness of the second optical anisotropic layer, and nx2 and ny2 are wavelengths of 550 nm. Second optically anisotropic layer surface for light Nx2 is the main refractive index in the plane, ny2 is the main refractive index in the direction perpendicular to nx2, and nz2 is the main refractive index in the thickness direction for light having a wavelength of 550 nm. )

[2] The horizontal alignment according to [1], wherein the first optical anisotropic layer satisfies the following [2], and the second optical anisotropic layer satisfies the following [3]: Laminated polarizing plate for liquid crystal display devices.
[2] nx1> ny1 ≧ nz1
[3] nz2> nx2 = ny2

[3] Laminated so as to satisfy 85 ° ≦ r ≦ 95 °, where r is an angle formed between the absorption axis of the first polarizing plate and the slow axis of the first optically anisotropic layer. The laminated polarizing plate for a horizontal alignment type liquid crystal display device according to the above [1] or [2].

[4] A horizontal alignment type liquid crystal display in which at least a first polarizing plate, a first optical anisotropic layer, a second optical anisotropic layer, a horizontal alignment type liquid crystal cell, and a second polarizing plate are arranged in this order. A horizontal alignment type liquid crystal display device, wherein the first optical anisotropic layer and the second optical anisotropic layer satisfy the following [1].
[1] -60 nm ≦ Rth1 + Rth2 ≦ 60 nm
(Here, Rth1 means a retardation value in the thickness direction of the first optically anisotropic layer. Rth1 is Rth1 = {(nx1 + ny1) / 2−nz1} × d1 [nm]). d1 is the thickness of the first optically anisotropic layer, nx1 and ny1 are the main refractive index in the first optically anisotropic layer surface for light having a wavelength of 550 nm, nx1 is the maximum main refractive index in the surface, ny1 represents the main refractive index in the direction orthogonal to nx1, nz1 is the main refractive index in the thickness direction for light having a wavelength of 550 nm, and Rth2 is the retardation in the thickness direction of the second optical anisotropic layer. Rth2 is Rth2 = [{nx2 + ny2} / 2−nz2] × d2 [nm], where d2 is the thickness of the second optical anisotropic layer, and nx2 and ny2 are wavelengths of 550 nm. Second optically anisotropic layer surface for light Nx2 is the main refractive index in the plane, ny2 is the main refractive index in the direction perpendicular to nx2, and nz2 is the main refractive index in the thickness direction for light having a wavelength of 550 nm. )

[5] The horizontal alignment according to [4], wherein the first optical anisotropic layer satisfies the following [2] and the second optical anisotropic layer satisfies the following [3]: Type liquid crystal display device.
[2] nx1> ny1 ≧ nz1
[3] nz2> nx2 = ny2

[6] Laminated so as to satisfy 85 ° ≦ r ≦ 95 °, where r is an angle formed between the absorption axis of the first polarizing plate and the slow axis of the first optically anisotropic layer. The horizontal alignment type liquid crystal display device according to the above [4] or [5].

[7] When the angle between the absorption axis of the first polarizing plate and the absorption axis of the second polarizing plate is s, 85 ° ≦ s ≦ 95 ° is satisfied, and the absorption axis of the second polarizing plate is The above [4] to [6], wherein the layers are stacked so as to satisfy −5 ° ≦ t ≦ 5 °, where t is an angle formed with the optical axis of the liquid crystal in the horizontal alignment type liquid crystal cell. ] The horizontal alignment type liquid crystal display device according to any one of the above.

The horizontal alignment type liquid crystal display device of the present invention has excellent viewing angle characteristics, bright display, and high contrast display in all directions.

It is a cross-sectional schematic diagram of the laminated polarizing plate for horizontal alignment type liquid crystal display devices of this invention. 6 is a schematic cross-sectional view of a horizontal alignment type liquid crystal display device used in Example 2. FIG. FIG. 6 is a plan view showing the angular relationship of each component of the horizontal alignment type liquid crystal display device used in Example 2. It is a figure which shows contrast ratio when the horizontal alignment type liquid crystal display device in Example 2 is seen from all directions. It is a figure which shows contrast ratio when the horizontal alignment type liquid crystal display device in Example 3 is seen from all directions. It is a figure which shows contrast ratio when the horizontal alignment type liquid crystal display device in Example 4 is seen from all directions. It is a figure which shows contrast ratio when the horizontal alignment type liquid crystal display device in the comparative example 1 is seen from all directions. It is a figure which shows contrast ratio when the horizontal alignment type liquid crystal display device in the comparative example 2 is seen from all directions. It is a figure which shows contrast ratio when the horizontal alignment type liquid crystal display device in the comparative example 3 is seen from all directions. It is a figure which shows contrast ratio when the horizontal alignment type liquid crystal display device in the comparative example 4 is seen from all directions.

Hereinafter, the present invention will be described in detail.
The laminated polarizing plate for a horizontal alignment type liquid crystal display device of the present invention is a laminated polarizing plate in which a first polarizing plate, a first optical anisotropic layer and a second optical anisotropic layer are laminated in this order.

Hereinafter, the constituent members used in the present invention will be described in order.
First, a horizontal alignment type liquid crystal cell used in the horizontal alignment type liquid crystal display device of the present invention will be described.
Although there is no restriction | limiting in particular as a liquid crystal cell, Various liquid crystal cells of a transmissive type, a reflective type, and a semi-transmissive type can be mentioned. The driving method of the liquid crystal cell is not particularly limited, and is a passive matrix method used for STN-LCDs, an active matrix method using active electrodes such as TFT (Thin Film Transistor) electrodes, TFD (Thin Film Diode) electrodes, and a plasma addressing method. Any driving method may be used.

The transparent substrate constituting the liquid crystal cell is not particularly limited as long as the liquid crystal material constituting the liquid crystal layer is aligned in a specific alignment direction. Specifically, a transparent substrate having the property of aligning the liquid crystal itself, a substrate itself lacking alignment ability, but a transparent substrate provided with an alignment film having the property of aligning liquid crystal, etc. Can also be used. Moreover, well-known things, such as ITO, can be used for the electrode of a liquid crystal cell. The electrode can usually be provided on the surface of the transparent substrate with which the liquid crystal layer is in contact. When a substrate having an alignment film is used, it can be provided between the substrate and the alignment film.

The material exhibiting liquid crystallinity for forming the liquid crystal layer is not particularly limited as long as it has a positive dielectric anisotropy, and various ordinary low-molecular liquid crystal substances and polymer liquid crystals capable of constituting various liquid crystal cells. Materials and mixtures thereof. Moreover, a pigment | dye, a non-liquid crystalline substance, etc. can also be added to these in the range which does not impair liquid crystallinity.

The horizontal alignment type liquid crystal display device of the present invention can be provided with other constituent members in addition to the constituent members described above. For example, by attaching a color filter to the liquid crystal display device of the present invention, a color liquid crystal display device capable of performing multicolor or full color display with high color purity can be manufactured.

Next, the optically anisotropic layer used in the present invention will be described in order.
First, the first optical anisotropic layer will be described.
As the first optically anisotropic layer, for example, a film made of an appropriate polymer such as a cyclic polyolefin such as polycarbonate or norbornene resin, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate, or polyamide. A composite film manufactured by a method in which a film is uniaxially or biaxially stretched or a method in which the width direction of a long film is thermally contracted by a heat shrinkable film as disclosed in JP-A-5-157911 and the phase difference is increased in the thickness direction. Examples thereof include a refractive film, an alignment film made of a liquid crystal material such as a liquid crystal polymer, and a film in which an alignment layer of the liquid crystal material is supported.

When the x direction, which is the direction in which the in-plane main refractive index is the maximum in the in-plane direction, and the y direction, which is the direction perpendicular to the x direction, are taken and the thickness direction is the z direction, positive uniaxial optical anisotropic The conductive layer has a relationship of nx> ny = nz as a refractive index. The positive biaxial optically anisotropic layer has a relationship of nx> nz> ny as a refractive index. The negative uniaxial optically anisotropic layer has a relationship of nx = ny> nz as a refractive index. The negative biaxial optically anisotropic layer has a relationship of nx> ny> nz as a refractive index.

The first optical anisotropic layer and the second optical anisotropic layer have a thickness of the first optical anisotropic layer d1, a maximum principal refractive index in the plane of the first optical anisotropic layer nx1, and The main refractive index in the direction orthogonal to nx1 is ny1, the main refractive index in the thickness direction is nz1, and the retardation value (Rth1 = {(nx1 + ny1) / 2−nz1} × d1 [ nm]), the thickness of the second optical anisotropic layer is d2, the maximum main refractive index in the plane of the second optical anisotropic layer is nx2, and the main refractive index in the direction orthogonal to nx2 is ny2, the thickness direction And nz21> nx2 ≧ ny2, and the retardation value in the thickness direction of light with a wavelength of 550 nm (Rth2 = {(nx2 + ny2) / 2−nz2} × d2 [nm]). The following formula [1] is satisfied.
[1] -60 nm ≦ Rth1 + Rth2 ≦ 60 nm
The above range is more preferably −60 nm ≦ Rth1 + Rth2 ≦ 0 nm. When Rth1 + Rth2 is in the above range, excellent viewing angle characteristics are exhibited.

As a more preferable embodiment of the present invention, the first optical anisotropic layer satisfies the following [2], and the second optical anisotropic layer satisfies the following [3].
[2] nx1> ny1 ≧ nz1
[3] nz2> nx2 = ny2

The first optically anisotropic layer contributes to the viewing angle compensation of the polarizing plate, and the retardation value (Re1 = (nx1-ny1) in the first optically anisotropic layer surface with respect to 550 nm light. Xd1 [nm]) is desirably in the range of 50 nm to 500 nm, preferably 80 nm to 480 nm, and more preferably 100 nm to 450 nm. When the Re1 value is within the above range, a sufficient viewing angle improvement effect can be obtained, and unnecessary coloring can be prevented when viewed from an oblique direction.
The retardation value (Rth1) in the thickness direction of the first optically anisotropic layer is preferably 30 nm to 750 nm, more preferably 40 nm to 500 nm, still more preferably 50 nm to 200 nm. When outside the above range, a sufficient viewing angle improvement effect may not be obtained, or unnecessary coloring may occur when viewed from an oblique direction.

In addition, when r is an angle formed by the absorption axis of the first polarizing plate and the slow axis of the first optically anisotropic layer, r is preferably in the range of 85 ° to 95 °, The angle is more preferably 88 to 92 °, and still more preferably about 90 ° (orthogonal). The absorption axis of the first polarizing plate and the long roll of the first optically anisotropic layer are substantially orthogonal (the crossing angle is within 90 ° ± 5 °, preferably within ± 2 °). Can be manufactured by laminating and integrating with roll-to-roll, but in order to integrate substantially orthogonally, the slow axis of the first optical anisotropic layer is It is necessary to arrange in a direction perpendicular to the roll length direction. For that purpose, it is better to produce the first optically anisotropic layer by lateral uniaxial stretching or biaxial stretching. In general, when manufactured by transverse uniaxial stretching or biaxial stretching, it is known that the refractive index relationship of the retardation film becomes negative biaxiality consisting of nx> ny> nz.

Next, the second optical anisotropic layer will be described.
The second optically anisotropic layer is preferably made of a homeotropically aligned liquid crystal film in which a liquid crystal material exhibiting positive uniaxiality is homeotropically aligned in a liquid crystal state and then fixed in alignment.
In the present invention, selection of a liquid crystal material and an alignment substrate is extremely important for obtaining a liquid crystal film in which the homeotropic alignment of the liquid crystal material is fixed.
The liquid crystal material used in the present invention contains at least a side chain type liquid crystalline polymer such as poly (meth) acrylate or polysiloxane as a main constituent component.
The side chain type liquid crystal polymer used in the present invention preferably has a polymerizable oxetanyl group at the terminal. More specifically, the side chain obtained by homopolymerizing the (meth) acrylic moiety of the (meth) acrylic compound having an oxetanyl group represented by the formula (1) or copolymerizing with another (meth) acrylic compound. A preferred example is a liquid crystalline polymer material.

In the above formula (1), R ₁ represents hydrogen or a methyl group, R ₂ represents hydrogen, a methyl group or an ethyl group, and L ₁ and L ₂ are each independently a single bond, —O—, —O—CO. -Represents either-or -CO-O-, M represents formula (2), formula (3) or formula (4), and n and m each independently represents an integer of 0 to 10.
-P1-L3-P2-L4-P3- (2)
-P1-L3-P3- (3)
-P3- (4)

In formulas (2) to (4), P1 and P2 each independently represent a group selected from formula (5), P3 represents a group selected from formula (6), and L3 and L4 each independently represents a single bond. , —CH═CH—, —C≡C—, —O—, —O—CO— or —CO—O—.

The method for synthesizing these (meth) acrylic compounds having an oxetanyl group is not particularly limited, and can be synthesized by applying a method used in a general organic chemical synthesis method. For example, by combining a site having an oxetanyl group and a site having a (meth) acrylic group by means such as Williamson's ether synthesis or ester synthesis using a condensing agent, oxetanyl group and (meth) acrylic group 2 A (meth) acrylic compound having an oxetanyl group having two reactive functional groups can be synthesized.

It is represented by the following formula (7) by homopolymerizing the (meth) acrylic group of the (meth) acrylic compound having an oxetanyl group represented by the formula (1) or copolymerizing with another (meth) acrylic compound. A side-chain liquid crystalline polymer substance containing units can be obtained. The polymerization conditions are not particularly limited, and normal radical polymerization or anionic polymerization conditions can be employed.

As an example of radical polymerization, a (meth) acryl compound is dissolved in a solvent such as dimethylformamide (DMF), and 2,2′-azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), or the like is used as an initiator. And reacting at 60 to 120 ° C. for several hours. Moreover, in order to make the liquid crystal phase appear stably, a copper (I) bromide / 2,2′-bipyridyl system, a 2,2,6,6-tetramethylpiperidinooxy free radical (TEMPO) system, etc. are used. A method of controlling the molecular weight distribution by conducting living radical polymerization as an initiator is also effective. These radical polymerizations are preferably performed under deoxygenation conditions.

Examples of anionic polymerization include a method in which a (meth) acrylic compound is dissolved in a solvent such as tetrahydrofuran (THF) and a strong base such as an organic lithium compound, an organic sodium compound, or a Grignard reagent is reacted as an initiator. In addition, the molecular weight distribution can be controlled by optimizing the initiator and the reaction temperature for living anionic polymerization. These anionic polymerizations must be performed strictly under dehydration and deoxygenation conditions.

In addition, the (meth) acryl compound to be copolymerized at this time is not particularly limited and may be anything as long as the synthesized polymer substance exhibits liquid crystallinity, but in order to increase the liquid crystallinity of the synthesized polymer substance, A (meth) acrylic compound having a mesogenic group is preferred. For example, a (meth) acrylic compound represented by the following formula can be exemplified as a preferred compound.

Here, R represents hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a cyano group.

The side chain type liquid crystalline polymer substance preferably contains 5 to 100 mol% of the unit represented by the formula (7), and particularly preferably contains 10 to 100 mol%. The side chain type liquid crystalline polymer substance preferably has a weight average molecular weight of 2,000 to 100,000, particularly preferably 5,000 to 50,000.

The liquid crystal material used in the present invention may contain various compounds that can be mixed without impairing liquid crystallinity in addition to the side chain liquid crystalline polymer substance. Examples of compounds that can be contained include compounds having a cationic polymerizable functional group such as an oxetanyl group, an epoxy group, and a vinyl ether group, various polymer substances having film-forming ability, and various low-molecular liquid crystal compounds having liquid crystallinity. And polymer liquid crystalline compounds. When the side chain liquid crystalline polymer substance is used as a composition, the proportion of the side chain liquid crystalline polymer substance in the entire composition is 10% by mass or more, preferably 30% by mass or more, and more preferably. Is 50 mass% or more. If the content of the side chain type liquid crystalline polymer substance is less than 10% by mass, the concentration of the polymerizable group in the composition becomes low, and the mechanical strength after polymerization becomes insufficient.

Further, after the liquid crystal material is subjected to an alignment treatment, the oxetanyl group is cationically polymerized and crosslinked to fix the liquid crystal state. For this reason, it is preferable that the liquid crystal material contains a photocation generator and / or a thermal cation generator that generates cations by an external stimulus such as light or heat. If necessary, various sensitizers may be used in combination.

The photo cation generator means a compound capable of generating a cation by irradiating with light having an appropriate wavelength, and examples thereof include organic sulfonium salt systems, iodonium salt systems, and phosphonium salt systems. Antimonates, phosphates, borates and the like are preferably used as counter ions of these compounds. Specific examples of the compound include Ar ₃ S ⁺ SbF ₆ ⁻ , Ar ₃ P ⁺ BF ₄ ⁻ , Ar ₂ I ⁺ PF ₆ ⁻ (wherein Ar represents a phenyl group or a substituted phenyl group), and the like. In addition, sulfonic acid esters, triazines, diazomethanes, β-ketosulfone, iminosulfonate, benzoinsulfonate and the like can also be used.

The thermal cation generator is a compound capable of generating a cation by being heated to an appropriate temperature, for example, benzylsulfonium salts, benzylammonium salts, benzylpyridinium salts, benzylphosphonium salts, hydrazinium salts, carboxylic acid esters, Examples thereof include sulfonic acid esters, amine imides, antimony pentachloride-acetyl chloride complexes, diaryliodonium salts-dibenzyloxycopper, and boron halide-tertiary amine adducts.

The amount of these cation generators added to the liquid crystal material varies depending on the structure of the mesogenic part and spacer part, the oxetanyl group equivalent, the alignment condition of the liquid crystal, etc. constituting the side chain type liquid crystalline polymer material to be used. However, it is usually 100 mass ppm to 20 mass%, preferably 1000 mass ppm to 10 mass%, more preferably 0.2 mass% to 7 mass%, most preferably based on the side chain type liquid crystalline polymer substance. Is in the range of 0.5% to 5% by weight. If the amount is less than 100 mass ppm, the amount of cations generated may not be sufficient and polymerization may not proceed. If the amount is more than 20 mass%, the remaining cation generator remains in the liquid crystal film. It is not preferable because there is a risk that the light resistance and the like may deteriorate due to an increase in the number of objects.

Next, the alignment substrate will be described.
As the alignment substrate, a substrate having a smooth plane is preferable, and examples thereof include a film or sheet made of an organic polymer material, a glass plate, and a metal plate. From the viewpoint of cost and continuous productivity, it is preferable to use a material made of an organic polymer. Examples of organic polymer materials include polyvinyl alcohol, polyimide, polyphenylene oxide, polyether ketone, polyether ether ketone, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, Examples include films made of transparent polymers such as polycarbonate polymers and acrylic polymers such as polymethyl methacrylate. Also, styrene polymers such as polystyrene, acrylonitrile / styrene copolymer, olefin polymers such as polyethylene, polypropylene, ethylene / propylene copolymer, cyclopolyolefins having cyclic or norbornene structure, vinyl chloride polymers, nylon and aromatic polyamides. Examples thereof include a film made of a transparent polymer such as an amide polymer. Furthermore, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers Examples thereof include a film made of a transparent polymer such as a polymer, an epoxy-based polymer, and a blend of the above polymers. Among these, plastic films such as triacetyl cellulose, polycarbonate, norbornene polyolefin used as an optical film are used. Examples of organic polymer film include norbornene such as ZEONOR (trade name, manufactured by ZEON CORPORATION), ZEONEX (trade name, manufactured by ZEON CORPORATION), Arton (trade name, manufactured by JSR Corporation), etc. A plastic film made of a polymer material having a structure is preferable because it has excellent optical properties. Moreover, as a metal film, the said film formed from aluminum etc. is mentioned, for example.

In order to stably obtain homeotropic alignment using the liquid crystal material described above, the material constituting these substrates has a long chain (usually 4 or more carbon atoms, preferably 8 or more) alkyl group, More preferably, the substrate surface has a compound layer having a long-chain alkyl group. Among them, it is preferable to form a layer made of polyvinyl alcohol having a long-chain alkyl group because the formation method is easy. These organic polymer materials may be used alone as a substrate, or may be formed as a thin film on another substrate. In the field of liquid crystal, rubbing treatment is generally performed by rubbing the substrate with a cloth or the like, but the homeotropic alignment liquid crystal film of the present invention has an alignment structure in which in-plane anisotropy basically does not occur. Therefore, the rubbing process is not necessarily required. However, it is more preferable to perform a weak rubbing treatment from the viewpoint of suppressing repelling when a liquid crystal material is applied. An important setting value that defines the rubbing condition is a peripheral speed ratio. This represents the ratio between the movement speed of the cloth and the movement speed of the substrate when the rubbing cloth is wound around a roll and rubbed while the substrate is rubbed. In the present invention, the weak rubbing treatment usually has a peripheral speed ratio of 50 or less, more preferably 25 or less, and particularly preferably 10 or less. When the peripheral speed ratio is greater than 50, the effect of rubbing is too strong, and the liquid crystal material cannot be completely aligned vertically, and there is a possibility that the alignment is tilted in the in-plane direction from the vertical direction.

Next, the manufacturing method of a homeotropic alignment liquid crystal film is demonstrated.
Although the method for producing the liquid crystal film is not limited to these, the above-mentioned liquid crystal material is spread on the above-mentioned alignment substrate, and after aligning the liquid crystal material, light irradiation and / or heat treatment is performed. It can manufacture by fixing the said orientation state.
The liquid crystal material is spread on the alignment substrate to form the liquid crystal material layer. The liquid crystal material is applied directly on the alignment substrate in a molten state, or the liquid crystal material solution is applied on the alignment substrate, and then the coating film is applied. And drying the solvent to distill off the solvent.

The solvent used for preparing the solution is not particularly limited as long as it can dissolve the liquid crystal material of the present invention and can be distilled off under suitable conditions. Generally, ketones such as acetone, methyl ethyl ketone, isophorone, and cyclohexanone, butoxyethyl Ethers such as alcohol, hexyloxyethyl alcohol, methoxy-2-propanol, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, esters such as ethyl acetate and ethyl lactate, phenols such as phenol and chlorophenol, N Amides such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, halogens such as chloroform, tetrachloroethane, dichlorobenzene, etc. Mixed system is preferably used. Further, in order to form a uniform coating film on the alignment substrate, a surfactant, an antifoaming agent, a leveling agent, or the like may be added to the solution.

Regardless of the method of directly applying the liquid crystal material or the method of applying the solution, the application method is not particularly limited as long as the uniformity of the coating film is ensured, and a known method may be adopted. it can. Examples thereof include spin coating, die coating, curtain coating, dip coating, and roll coating.
In the method of applying a liquid crystal material solution, it is preferable to include a drying step for removing the solvent after the application. As long as the uniformity of a coating film is maintained, this drying process can employ | adopt a well-known method, without being specifically limited. For example, a method such as a heater (furnace) or hot air blowing may be used.

The film thickness of the liquid crystal film cannot be generally described because it depends on the method of the liquid crystal display device and various optical parameters, but is usually 0.2 μm to 10 μm, preferably 0.3 μm to 5 μm, more preferably 0.5 μm. ~ 2 μm. When the film thickness is thinner than 0.2 μm, there is a possibility that a sufficient viewing angle improvement or brightness enhancement effect cannot be obtained. If it exceeds 10 μm, the liquid crystal display device may be unnecessarily colored.

Subsequently, the liquid crystal material layer formed on the alignment substrate is liquid crystal aligned by a method such as heat treatment, and is cured and fixed by light irradiation and / or heat treatment. In the first heat treatment, the liquid crystal is aligned by the self-alignment ability inherent in the liquid crystal material by heating to the liquid crystal phase expression temperature range of the used liquid crystal material. The conditions for the heat treatment cannot be generally stated because the optimum conditions and limit values vary depending on the liquid crystal phase behavior temperature (transition temperature) of the liquid crystal material to be used, but are usually 10 ° C. to 250 ° C., preferably in the range of 30 ° C. to 160 ° C. It is preferable that the heat treatment is performed at a temperature equal to or higher than the glass transition point (Tg) of the liquid crystal material, more preferably at a temperature higher by 10 ° C. than Tg. If the temperature is too low, the liquid crystal alignment may not proceed sufficiently, and if the temperature is high, the cationic polymerizable reactive group in the liquid crystal material and the alignment substrate may be adversely affected. The heat treatment time is usually in the range of 3 seconds to 30 minutes, preferably 10 seconds to 10 minutes. If the heat treatment time is shorter than 3 seconds, the liquid crystal alignment may not be completed sufficiently, and if the heat treatment time exceeds 30 minutes, the productivity is deteriorated.
After the liquid crystal material layer is formed into a liquid crystal alignment by a method such as heat treatment, the liquid crystal material is cured by a polymerization reaction of oxetanyl groups in the composition while maintaining the liquid crystal alignment state. The curing step is aimed at fixing the liquid crystal alignment state of the completed liquid crystal alignment by a curing (crosslinking) reaction and modifying it into a stronger film.

Since the liquid crystal material of the present invention has a polymerizable oxetanyl group, as described above, it is preferable to use a cationic polymerization initiator (cation generator) for the polymerization (crosslinking) of the reactive group. As the polymerization initiator, it is preferable to use a photo cation generator rather than a thermal cation generator.
When a photo cation generator is used, the liquid crystal material can be obtained by adding the photo cation generator to the heat treatment for aligning the liquid crystal under dark conditions (light blocking conditions that do not cause the photo cation generator to dissociate). The liquid crystal can be aligned with sufficient fluidity without curing until the alignment stage. Thereafter, the liquid crystal material layer is cured by generating cations by irradiating light from a light source that emits light of an appropriate wavelength.

As a light irradiation method, a photocation is generated by irradiating light from a light source such as a metal halide lamp, a high pressure mercury lamp, a low pressure mercury lamp, a xenon lamp, an arc lamp, or a laser having a spectrum in the absorption wavelength region of the photocation generator used. Cleave the generator. The dose per square centimeter is usually in the range of 1 to 2000 mJ, preferably 10 to 1000 mJ, as the cumulative dose. However, this is not the case when the absorption region of the photocation generator and the spectrum of the light source are remarkably different, or when the liquid crystal material itself has the ability to absorb the light source wavelength. In these cases, it is possible to adopt a method such as using a suitable photosensitizer or a mixture of two or more photocation generators having different absorption wavelengths.
The temperature at the time of light irradiation needs to be within a temperature range in which the liquid crystal material takes liquid crystal alignment. In order to sufficiently enhance the curing effect, it is preferable to perform light irradiation at a temperature equal to or higher than Tg of the liquid crystal material.

The liquid crystal material layer produced by the above process is a sufficiently strong film. Specifically, the mesogens are three-dimensionally bonded by the curing reaction, and not only the heat resistance (the upper limit temperature for maintaining the liquid crystal alignment) is improved as compared to before curing, but also scratch resistance, abrasion resistance, crack resistance. The mechanical strength such as property is also greatly improved.
As the alignment substrate, it is not optically isotropic, or the liquid crystal film to be obtained is finally opaque in the intended use wavelength region, or the alignment substrate is too thick, resulting in problems in actual use. When there is a problem such as, a form transferred from a form formed on an alignment substrate to a stretched film having a retardation function may be used. As a transfer method, a known method can be adopted. For example, as described in JP-A-4-57017 and JP-A-5-333313, a liquid crystal film layer is laminated with a substrate different from the alignment substrate via an adhesive or an adhesive, and if necessary, Examples thereof include a method of transferring only a liquid crystal film by performing a surface curing treatment using an adhesive or an adhesive and peeling the alignment substrate from the laminate.
The pressure-sensitive adhesive or adhesive used for transfer is not particularly limited as long as it is of optical grade, and generally used ones such as acrylic, epoxy, and urethane can be used.

The homeotropic alignment liquid crystal layer obtained as described above can be quantified by measuring the optical phase difference of the liquid crystal layer at an angle inclined from the normal incidence. In the case of homeotropic alignment liquid crystal layers, this retardation value is symmetric with respect to normal incidence. Several methods can be used for measuring the optical phase difference. For example, an automatic birefringence measuring apparatus (manufactured by Oji Scientific Instruments) and a polarizing microscope can be used. This homeotropic alignment liquid crystal layer appears black between the crossed Nicols polarizing plates. Thus, homeotropic orientation was evaluated.

The Re2 value and Rth2 value, which are optical parameters of the homeotropic alignment liquid crystal film, cannot be generally described because they depend on the type of the liquid crystal display device and various optical parameters, but the homeotropic alignment for monochromatic light of 550 nm The retardation value (Re2) in the plane of the liquid crystal film is preferably 0 nm to 20 nm, more preferably 0 nm to 10 nm, still more preferably 0 nm to 5 nm, and retardation in the thickness direction. The value (Rth2) is preferably from −500 to −30 nm, more preferably from −400 to −50 nm, still more preferably from −400 to −100 nm.

By setting the Rth2 value in the above range, the viewing angle improving film of the liquid crystal display device can widen the viewing angle while correcting the color tone of the liquid crystal display. When the Rth2 value is larger than −30 nm or smaller than −500 nm, a sufficient viewing angle improving effect cannot be obtained, or unnecessary coloring may occur when viewed from an oblique direction. Moreover, the front characteristic of a liquid crystal display element can be improved by making Re2 value into 20 nm or less.

The first polarizing plate and the second polarizing plate used in the present invention will be described.
As the first polarizing plate and the second polarizing plate used in the present invention, those having a protective film on one side or both sides of the polarizer are usually used. In the case of a structure having a protective film only on one side, the first optically anisotropic layer also functions as a protective film. The laminated polarizing plate of the present invention is laminated so that the slow axis of the first optically anisotropic layer and the absorption axis of the first polarizing plate are substantially orthogonal (intersection angle is within 90 ° ± 5 °). In addition, by using a negative biaxial optically anisotropic layer stretched in the width direction, it is possible to perform integral production with a roll-to-roll.

The polarizer is not particularly limited, and various types can be used. For example, for a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, an ethylene / vinyl acetate copolymer partially saponified film. And polyene-based oriented films such as those obtained by adsorbing dichroic substances such as iodine and dichroic dyes and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, those obtained by stretching a polyvinyl alcohol film and adsorbing and orienting a dichroic material (iodine, dye) are preferably used. The thickness of the polarizer is not particularly limited, but is generally about 5 to 80 μm.

A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous iodine solution and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution of boric acid or potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

The protective film provided on one side or both sides of the polarizer preferably has excellent transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic properties, and the like. Examples of the material for the protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymer, and the like. Examples thereof include styrene polymers such as coalesced (AS resin), polycarbonate polymers, and the like. Also, polyolefin polymers such as polyethylene, polypropylene, ethylene / propylene copolymers, polyolefins having cycloolefin or norbornene structures, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfones Polymer, polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or Examples of the polymer that forms the protective film include blends of the aforementioned polymers. Other examples include films made of thermosetting or ultraviolet curable resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone. The thickness of the protective film is generally 500 μm or less, and preferably 1 to 300 μm. In particular, the thickness is preferably 5 to 200 μm.

The protective film is preferably an optically isotropic substrate. For example, a triacetyl cellulose (TAC) film such as Fujitac (product of Fujifilm) or Konicatak (product of Konica Minolta Opto), Arton film (product of JSR) And ZEONOR film, ZEONEX film (product of ZEON Corporation), cycloolefin polymer, TPX film (product of Mitsui Chemicals), acrylene film (product of Mitsubishi Rayon Co., Ltd.) From the viewpoints of flatness, heat resistance and moisture resistance, triacetyl cellulose and cycloolefin polymers are preferred.
In addition, when providing a protective film in the both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used. The polarizer and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of aqueous adhesives include polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, aqueous polyurethanes, aqueous polyesters, and the like.

As the protective film, a hard coat layer, an antireflection treatment, an anti-sticking treatment, or a treatment subjected to diffusion or anti-glare treatment can be used.
Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipping properties with an appropriate ultraviolet curable resin such as acrylic or silicone is applied to the protective film. It can be formed by a method of adding to the surface. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

Anti-glare treatment is applied for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, roughening by sandblasting or embossing. It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a method or a compounding method of transparent fine particles. Examples of the fine particles to be included in the formation of the fine surface uneven structure include conductive particles made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. In the case of forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.
The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the protective film itself, or can be provided separately from the transparent protective layer as an optical layer.

The first polarizing plate, the first optically anisotropic layer, and the second optically anisotropic layer can be produced by sticking each other through an adhesive layer. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based or rubber-based polymer is appropriately used as a base polymer. Can be selected and used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

The pressure-sensitive adhesive layer can be formed by an appropriate method. For example, a pressure-sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of an appropriate solvent alone or a mixture such as toluene and ethyl acetate is prepared. , A method in which it is directly attached on the liquid crystal layer by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on the separator according to the above and transferred onto the liquid crystal layer Examples include methods. The pressure-sensitive adhesive layer includes, for example, natural and synthetic resins, in particular, tackifier resins, glass fibers, glass beads, metal powder, fillers made of other inorganic powders, pigments, colorants, You may contain the additive added to adhesion layers, such as antioxidant. Moreover, the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.
In addition, when bonding each optically anisotropic layer mutually through an adhesive layer, the film surface can be surface-treated and adhesiveness with an adhesive layer can be improved. The surface treatment means is not particularly limited, and a surface treatment method such as corona discharge treatment, sputtering treatment, low-pressure UV irradiation, or plasma treatment that can maintain the transparency of each optically anisotropic layer can be suitably employed. Among these surface treatment methods, corona discharge treatment is good.

The horizontal alignment type liquid crystal display device of the present invention includes a laminated polarizing plate of the present invention, a horizontal alignment type liquid crystal composed of at least a first polarizing plate, a first optical anisotropic layer, and a second optical anisotropic layer. The cell and the second polarizing plate are arranged in this order.

In the horizontal alignment type liquid crystal display device of the present invention, s is in the range of 85 ° to 95 °, where s is the angle formed by the absorption axis of the first polarizing plate and the absorption axis of the second polarizing plate. Preferably, it is 88 to 92 °, more preferably about 90 ° (orthogonal). When s deviates from the upper and lower ranges, light leakage of the horizontal alignment type liquid crystal display device is large and the visibility is remarkably deteriorated.
Further, when the angle between the absorption axis of the second polarizing plate and the optical axis of the liquid crystal in the horizontal alignment type liquid crystal cell is t, the layers are laminated so as to satisfy −5 ° ≦ t ≦ 5 °. However, when t is out of the upper and lower ranges, light leakage of the horizontal alignment type liquid crystal display device is large, and the visibility is remarkably deteriorated.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In addition, each analysis method used in the Example is as follows.
⁽¹⁾ Measurement compound of 1 H-NMR was dissolved in deuterated chloroform and measured by ¹ H-NMR of 400 MHz (Variant Co. INOVA-400).
(2) Measurement of GPC The compound was dissolved in tetrahydrofuran, and TSK-GELSuperH1000, SuperH2000, SuperH3000, and SuperH4000 were connected in series with an 8020 GPC system manufactured by Tosoh Corporation and measured using tetrahydrofuran as an eluent. Polystyrene standards were used for molecular weight calibration.
(3) Microscope observation The alignment state of the liquid crystal was observed with an Olympus BH2 polarizing microscope.
(4) Film thickness measurement method SURFACE TEXTUREALYSIS SYSTEM Dektak3030ST manufactured by SLOAN was used. In addition, a method of obtaining the film thickness from the interference wave measurement (UV-visible / near-infrared spectrophotometer V-570 manufactured by JASCO Corporation) and the refractive index data was used in combination.
(5) Parameter measurement of liquid crystal film Obi Scientific Instruments Co., Ltd. automatic birefringence meter KOBRA21ADH was used.

[Reference Example 1]
(Production of polarizer)
The polyvinyl alcohol film was immersed in warm water to swell, then dyed in an iodine / potassium iodide aqueous solution, and then uniaxially stretched in an aqueous boric acid solution to obtain a polarizer. This polarizer was examined for single transmittance, parallel transmittance and orthogonal transmittance with a spectrophotometer. As a result, the transmittance was 43.5%, and the polarization degree was 99.9%.

[Reference Example 2]
A liquid crystalline polymer represented by the following formula (8) was synthesized. The molecular weight was Mn = 8000 and Mw = 15000 in terms of polystyrene. In addition, although Formula (8) is described with the structure of a block polymer, it represents the component ratio of a monomer.

After dissolving 1.0 g of the polymer of the formula (8) in 9 ml of cyclohexanone and adding 0.1 g of a triallylsulfonium hexafluoroantimonate 50% propylene carbonate solution (manufactured by Aldrich) in the dark, A liquid crystal material solution was prepared by filtration through a 0.45 μm polytetrafluoroethylene filter.
The alignment substrate was prepared as follows. A 38 μm-thick polyethylene naphthalate film (manufactured by Teijin Limited) was cut into a 15 cm square, and a 5% by mass solution of alkyl-modified polyvinyl alcohol (PVA: Kuraray Co., Ltd., MP-203) (the solvent was water and isopropyl A mixed solvent having an alcohol mass ratio of 1: 1) was applied by spin coating, dried on a hot plate at 50 ° C. for 30 minutes, and then heated in an oven at 120 ° C. for 10 minutes. Subsequently, it was rubbed with a rayon rubbing cloth. The film thickness of the obtained PVA layer was 1.2 μm. The peripheral speed ratio during rubbing (moving speed of rubbing cloth / moving speed of substrate film) was 4.
The liquid crystal material solution described above was applied to the alignment substrate thus obtained by spin coating. Next, it was dried on a hot plate at 60 ° C. for 10 minutes and heat-treated in an oven at 150 ° C. for 2 minutes to align the liquid crystal material. Next, the sample is placed in close contact with an aluminum plate heated to 60 ° C., and then a 600 mJ / cm ² ultraviolet light (however, measured at 365 nm) is irradiated with a high-pressure mercury lamp lamp to cure the liquid crystal material. It was.

Since the polyethylene naphthalate film used as the substrate has a large birefringence and is not preferable as an optical film, the obtained liquid crystalline film on the alignment substrate is converted to a triacetyl cellulose (TAC) film via an ultraviolet curable adhesive. Transcribed to. That is, on the cured liquid crystal material layer on the polyethylene naphthalate film, an adhesive is applied to a thickness of 5 μm, laminated with a TAC film, and irradiated with ultraviolet rays from the TAC film side to cure the adhesive. After that, the polyethylene naphthalate film and the PVA layer were peeled off.

When the obtained optical film (liquid crystal layer / adhesive layer / TAC film) is observed under a polarizing microscope, it has a uniform uniaxial refractive index structure from conoscopic observation with uniform orientation of monodomains without disclination. It was found to be homeotropic alignment. The retardation in the in-plane direction of the TAC film and the liquid crystal layer measured using KOBRA21ADH was 0.5 nm, and the retardation in the thickness direction was −119 nm. Since the TAC film alone was negative uniaxial, the in-plane retardation was 0.5 nm, and the retardation in the thickness direction was +35 nm, the retardation of the liquid crystal layer alone was Re2 of 0 nm and Rth2 of It was estimated to be -154 nm. In Example 1 and later, the TAC film of the substrate was removed and only the homeotropic alignment liquid crystal layer was taken out and used when bonded to another substrate. The thickness of the homeotropic alignment liquid crystal layer was 0.9 μm. The refractive index in each direction was in a relationship of nz2> nx2 = ny2.
The homeotropic alignment liquid crystal layer corresponds to the second optically anisotropic layer.

[Example 1]
The structure of the laminated polarizing plate will be described with reference to FIG.
A triacetyl cellulose (TAC) film having a thickness of 40 μm, a front phase difference of 6 nm, and a thickness direction retardation of 60 nm is bonded as a protective film to one side of the polarizer obtained in Reference Example 1 via a polyvinyl alcohol adhesive. Thus, the first polarizing plate 1 was formed. The other side of the first polarizing plate 1 is delayed in the roll width direction produced by lateral uniaxial stretching with the absorption axis of the first polarizing plate 1 having an absorption axis in the roll longitudinal direction via a polyvinyl alcohol adhesive. The first optically anisotropic layer 3 made of norbornene-based resin having a phase axis and the absorption axis of the first polarizing plate 1 and the slow axis of the first optically anisotropic layer 3 are bonded so as to be orthogonal to each other. And the 2nd optically anisotropic layer 4 produced by the reference example 2 was bonded together via the acrylic adhesive, and the laminated polarizing plate 5 was obtained. Here, Re1 of the first optical anisotropic layer 3 has a phase difference of 115 nm, and Rth1 has a phase difference of 103.5 nm. The refractive index in each direction was in the relationship of nx1>ny1> nz1.

[Example 2]
A horizontal alignment type liquid crystal display device used in Example 2 will be described with reference to FIGS.
A transparent electrode 7 is formed of a material having a high transmittance made of an ITO layer on the substrate 6, and a liquid crystal layer 9 made of a liquid crystal material having a positive dielectric anisotropy is sandwiched between the transparent electrode 7 and the substrate 8. .
A liquid crystal material exhibiting positive dielectric anisotropy is used for the liquid crystal layer 9. When an electric field is applied in the plane direction of the transparent electrode 7, the liquid crystal molecules rotate in the direction of the electric field.

The laminated polarizing plate 5 produced in Example 1 was disposed on the display surface side (upper side in the figure) of the horizontal alignment type liquid crystal cell 10. A linearly polarizing plate (SQW-062 manufactured by Sumitomo Chemical Co., Ltd.) was disposed as the second polarizing plate 11 on the back side (lower side of the figure) of the horizontal alignment type liquid crystal cell 10. Rth of triacetyl cellulose used for the support substrate of the linearly polarizing plate was 35 nm.
The directions of the absorption axes of the first polarizing plate 1 and the second polarizing plate 11 indicated by arrows in FIG. 3 were 90 degrees and 0 degrees in the plane, respectively. The first optically anisotropic layer 3 is formed of an optical element having an in-plane optical axis and negative biaxial optical anisotropy. The slow axis orientation of the first optically anisotropic layer 3 indicated by an arrow in FIG. 3 is 0 degree, and the in-plane Re1 has a phase difference of 115 nm and the Rth1 has a phase difference of 103.5 nm.
The second optically anisotropic layer 4 made of a homeotropic alignment liquid crystal film exhibits a phase difference in which Re2 is 0 nm and Rth2 is −154 nm.
FIG. 4 shows the contrast ratio from all directions, where the transmittance ratio (white display) / (black display) of black display 0V and white display 5V is used as the contrast ratio. Contrast contour lines were set to 6000, 3000, 1000, and 200 in order from the inside. The concentric circles indicate an angle of 20 degrees from the center. Therefore, the outermost circle shows 80 degrees from the center (the same applies to the following figures). When the contrast ratio was viewed in all directions, it was found that the contrast ratio was high in all directions and good viewing angle characteristics were obtained.

[Example 3]
The in-plane Re1 of the first optically anisotropic layer 3 made of norbornene-based resin is 125 nm, Rth1 is 87.5 nm, and the in-plane Re2 of the second optically anisotropic layer 4 made of homeotropic alignment liquid crystal film is 0 nm. A horizontal alignment type liquid crystal display device was produced in the same manner as in Example 2 except that Rth2 was changed to -134 nm.
FIG. 5 shows the contrast ratio from all directions, where the transmittance ratio (white display) / (black display) of black display 0V and white display 5V is used as the contrast ratio. When the contrast ratio was viewed in all directions, it was found that the contrast ratio was high in all directions and good viewing angle characteristics were obtained.

[Example 4]
The in-plane Re1 of the first optically anisotropic layer 3 made of norbornene-based resin is 140 nm, Rth1 is 70 nm, the in-plane Re2 of the second optically anisotropic layer 4 made of homeotropic alignment liquid crystal film is 0 nm, Rth2 A horizontal alignment type liquid crystal display device was produced in the same manner as in Example 2 except that the thickness was −113 nm.
FIG. 6 shows the contrast ratio from all directions, where the transmittance ratio (white display) / (black display) of black display 0V and white display 5V is used as the contrast ratio. When the contrast ratio was viewed in all directions, it was found that the contrast ratio was high in all directions and good viewing angle characteristics were obtained.

[Comparative Example 1]
A horizontal alignment type liquid crystal display device was produced in the same manner as in Example 2 except that Rth2 of the second optically anisotropic layer 4 made of homeotropic alignment liquid crystal film was set to -200 nm. As a result, Rth1 + Rth2 = −96.5 nm.
FIG. 7 shows the contrast ratio from all directions, with the transmittance ratio (white display) / (black display) of black display 0V and white display 5V as the contrast ratio. When the contrast ratio was viewed in all directions, it was found that the viewing angle characteristics deteriorated particularly in the four directions of upper right, upper left, lower right, and lower left.

[Comparative Example 2]
A horizontal alignment type liquid crystal display device was produced in the same manner as in Example 2 except that the first optically anisotropic layer 3 made of norbornene resin was not used.
FIG. 8 shows the contrast ratio from all directions, where the transmittance ratio (white display) / (black display) of black display 0V and white display 5V is used as the contrast ratio. When the contrast ratio was viewed in all directions, it was found that the viewing angle characteristics deteriorated particularly in the four directions of upper right, upper left, lower right, and lower left.

[Comparative Example 3]
A horizontal alignment type liquid crystal display device was produced in the same manner as in Example 2 except that the second optically anisotropic layer 4 made of homeotropic alignment liquid crystal film was not used.
FIG. 9 shows the contrast ratio from all directions, where the transmittance ratio (white display) / (black display) of black display 0V and white display 5V is used as the contrast ratio. When the contrast ratio was viewed in all directions, it was found that the viewing angle characteristics deteriorated particularly in the four directions of upper right, upper left, lower right, and lower left.

[Comparative Example 4]
A horizontal alignment type liquid crystal is obtained in the same manner as in Example 2 except that the first optical anisotropic layer 3 made of norbornene resin and the second optical anisotropic layer 4 made of homeotropic alignment liquid crystal film are not used. A display device was produced.
FIG. 10 shows the contrast ratio from all directions, where the transmittance ratio (white display) / (black display) of black display 0V and white display 5V is used as the contrast ratio. When the contrast ratio was viewed in all directions, it was found that the viewing angle characteristics deteriorated particularly in the four directions of upper right, upper left, lower right, and lower left.

[Comparative Example 5]
Instead of the homeotropic alignment liquid crystal film, the second optical anisotropic layer 4 is a negative uniaxial TAC film with an in-plane retardation value of 0.5 nm and a thickness direction retardation value of +35 nm. A horizontal alignment type liquid crystal display device was produced in the same manner as in Example 2 except that. Since Re2 = 0.5 nm and Rth = + 35 nm, nx2>ny2> nz2. When the contrast ratio of the transmittance ratio (white display) / (black display) of black display 0V and white display 5V was measured, it was particularly low in the four directions of upper right, upper left, lower right, and lower left when viewed in all directions. As a result, it was found that the viewing angle characteristics deteriorate.

[Comparative Example 6]
Horizontally aligned liquid crystal display in the same manner as in Example 2 except that the angle formed between the absorption axis of the first polarizing plate and the slow axis of the first optically anisotropic layer made of norbornene resin was set to 0 °. A device was made. When the contrast ratio of the transmittance ratio (white display) / (black display) of black display 0V and white display 5V was measured, it was particularly low in the four directions of upper right, upper left, lower right, and lower left when viewed in all directions. As a result, it was found that the viewing angle characteristics deteriorate.

Claims

A laminated polarizing plate for a horizontal alignment type liquid crystal display device in which at least a first polarizing plate, a first optically anisotropic layer, and a second optically anisotropic layer are laminated in this order, wherein the first optically different layer is provided. A laminated polarizing plate for a horizontal alignment type liquid crystal display device, wherein the isotropic layer and the second optically anisotropic layer satisfy the following [1].
[1] -60 nm ≦ Rth1 + Rth2 ≦ 60 nm
(Here, Rth1 means a retardation value in the thickness direction of the first optically anisotropic layer. Rth1 is Rth1 = {(nx1 + ny1) / 2−nz1} × d1 [nm]). d1 is the thickness of the first optically anisotropic layer, nx1 and ny1 are the main refractive index in the first optically anisotropic layer surface for light having a wavelength of 550 nm, nx1 is the maximum main refractive index in the surface, ny1 represents the main refractive index in the direction orthogonal to nx1, nz1 is the main refractive index in the thickness direction for light having a wavelength of 550 nm, and Rth2 is the retardation in the thickness direction of the second optical anisotropic layer. Rth2 is Rth2 = [{nx2 + ny2} / 2−nz2] × d2 [nm], where d2 is the thickness of the second optical anisotropic layer, and nx2 and ny2 are wavelengths of 550 nm. Second optically anisotropic layer surface for light Nx2 is the main refractive index in the plane, ny2 is the main refractive index in the direction perpendicular to nx2, and nz2 is the main refractive index in the thickness direction for light having a wavelength of 550 nm. )
2. The horizontal alignment type liquid crystal display device according to claim 1, wherein the first optical anisotropic layer satisfies the following [2] and the second optical anisotropic layer satisfies the following [3]. Laminated polarizing plate.
[2] nx1> ny1 ≧ nz1
[3] nz2> nx2 = ny2
Laminated so as to satisfy 85 ° ≦ r ≦ 95 °, where r is an angle formed between the absorption axis of the first polarizing plate and the slow axis of the first optically anisotropic layer. The laminated polarizing plate for a horizontal alignment type liquid crystal display device according to claim 1 or 2.
A horizontal alignment type liquid crystal display device in which at least a first polarizing plate, a first optical anisotropic layer, a second optical anisotropic layer, a horizontal alignment type liquid crystal cell, and a second polarizing plate are arranged in this order. The horizontal alignment type liquid crystal display device, wherein the first optical anisotropic layer and the second optical anisotropic layer satisfy the following [1].
[1] -60 nm ≦ Rth1 + Rth2 ≦ 60 nm
(Here, Rth1 means a retardation value in the thickness direction of the first optically anisotropic layer. Rth1 is Rth1 = {(nx1 + ny1) / 2−nz1} × d1 [nm]). d1 is the thickness of the first optically anisotropic layer, nx1 and ny1 are the main refractive index in the first optically anisotropic layer surface for light having a wavelength of 550 nm, nx1 is the maximum main refractive index in the surface, ny1 represents the main refractive index in the direction orthogonal to nx1, nz1 is the main refractive index in the thickness direction for light having a wavelength of 550 nm, and Rth2 is the retardation in the thickness direction of the second optical anisotropic layer. Rth2 is Rth2 = [{nx2 + ny2} / 2−nz2] × d2 [nm], where d2 is the thickness of the second optical anisotropic layer, and nx2 and ny2 are wavelengths of 550 nm. Second optically anisotropic layer surface for light Nx2 is the main refractive index in the plane, ny2 is the main refractive index in the direction perpendicular to nx2, and nz2 is the main refractive index in the thickness direction for light having a wavelength of 550 nm. )
5. The horizontal alignment type liquid crystal display device according to claim 4, wherein the first optical anisotropic layer satisfies the following [2] and the second optical anisotropic layer satisfies the following [3]. .
[2] nx1> ny1 ≧ nz1
[3] nz2> nx2 = ny2
Laminated so as to satisfy 85 ° ≦ r ≦ 95 °, where r is an angle formed between the absorption axis of the first polarizing plate and the slow axis of the first optically anisotropic layer. A horizontal alignment type liquid crystal display device according to claim 4 or 5.
When the angle between the absorption axis of the first polarizing plate and the absorption axis of the second polarizing plate is s, 85 ° ≦ s ≦ 95 ° is satisfied, and the absorption axis of the second polarizing plate and the horizontal alignment type are satisfied. 7. The laminated structure according to claim 4, wherein the layers are laminated so as to satisfy −5 ° ≦ t ≦ 5 °, where t is an angle formed with the optical axis of the liquid crystal in the liquid crystal cell. Horizontal alignment type liquid crystal display device.