JP2008191630A - Elliptically polarizing plate, manufacturing method thereof, luminance improving film, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elliptically polarizing plate which can be stably manufactured without requiring a complicated process such as light irradiation in an inactive gas environment, is excellent in alignment holding ability after fixing liquid crystal alignment and mechanical strength and is capable of controlling retardation in the thickness direction over a wide range, to provide a manufacturing method of the elliptically polarizing plate, to provide a luminance improving film using the elliptically polarizing plate, and to provide an image display device using the elliptically polarizing plate and the luminance improving film. <P>SOLUTION: The elliptically polarizing plate is manufactured by stacking a homeotropically aligned liquid crystal layer in which the homeotropic alignment is fixed, a retardation film having retardation function and a linearly polarizing plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an elliptically polarizing plate in which a homeotropic alignment liquid crystal film, a retardation film having a retardation function, and a linear polarizing plate are laminated, and a method for producing the same. The elliptically polarizing plate of the present invention can be used alone or in combination with other optical films as an optical film such as a quarter-wave film, a viewing angle compensation film, an optical compensation film, an elliptical polarizing film, and a luminance improvement of a liquid crystal display device or the like. Can be used as a film. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic electroluminescence device (organic EL display device) or a plasma display panel (PDP) using the elliptically polarizing plate and the brightness enhancement film.

  In an image display device such as a liquid crystal display device, contrast and the like change with a change in viewing angle due to birefringence by liquid crystal or the like. In order to prevent such a contrast change and the like, in a liquid crystal display device or the like, a technique has been proposed in which a retardation plate is disposed in a liquid crystal cell and optical characteristics based on birefringence are compensated to improve viewing angle characteristics. As such a retardation plate, an elliptically polarizing plate in which a uniaxially or biaxially stretched film and a linearly polarizing plate are laminated is usually used, but it has a viewing angle characteristic satisfactory for all liquid crystal cells. Absent.

  In Patent Document 1, one or two or more heat-shrinkable films are bonded to one or both sides of a long film made of a thermoplastic resin, and the shrinkage force of the heat-shrinkable film is measured while gripping with a tenter. The width direction of the long film is contracted at a magnification A of 0.7 times or more to less than 1.0 times, and the film width excluding the grip holding part after the contraction treatment is defined as 100. 100-magnification (A × 100) × 0.15 or less is disclosed. A continuous production method of a retardation film is disclosed in which the width direction is stretched and widened at a stretching ratio (%) satisfying 100 or less.

  According to the said manufacturing method, since it extends also in the thickness direction, the phase difference plate which has a phase difference also in the thickness direction is obtained. However, in the manufacturing method, when the in-plane main refractive index of the obtained retardation plate is nx, ny, the refractive index in the thickness direction is nz, and nx> ny, Nz = (nx−nz) Nz defined by / (nx−ny) is −1.0 <Nz <0.1, and there is a limit to stretching in the thickness direction, and the retardation in the thickness direction cannot be controlled over a wide range. Moreover, in the said manufacturing method, since the elongate film is heat-shrinked with the heat shrink film and it is extended | stretched in the thickness direction, thickness of the obtained phase difference plate increases rather than a elongate film. That is, the thickness of the retardation plate obtained by the manufacturing method is about 50 to 100 μm, which is not sufficient for the thinning required for a liquid crystal display device or the like.

  As a method for increasing the retardation in the thickness direction, it is considered a shortcut to use homeotropic alignment (vertical alignment) of liquid crystals. Homeotropic alignment of liquid crystal molecules is that the long-axis molecular direction of the liquid crystal is aligned in a direction substantially perpendicular to the substrate. It is well known that homeotropic alignment can be obtained by applying an electric field by putting liquid crystal in two glass substrates as in a liquid crystal display device, but it is very difficult to make this alignment state into a film. However, there are problems with the methods reported in the past. In Patent Document 2 to Patent Document 4, a main chain polymer liquid crystal compound is homeotropically aligned, and then a film is obtained by glass fixation. However, in homeotropic alignment, it is surmised that there is a problem that cracks are likely to occur in the in-plane direction because the polymers are aligned in the film thickness direction, but in these reports, measures such as strengthening the material by crosslinking are taken. Absent. In Patent Document 5, the homeotropic alignment of the side chain polymer liquid crystal compound is fixed by vitrification. However, it is considered that there is a problem in strength as compared with the main chain polymer liquid crystal compound. In Patent Documents 6 to 7, a polymerizable low-molecular liquid crystal compound is added to the side-chain polymer liquid crystal compound. However, since the low-molecular liquid crystal compound is polymerized alone, the strength of the side-chain polymer liquid crystal compound is reinforced. Has its limits. In Patent Document 8, a material in which a radical polymerizable group, or a cationic polymerizable group such as a vinyl ether group or an epoxy group is introduced into a side chain type polymer liquid crystal compound is used. However, since radical polymerization is generally subjected to oxygen inhibition, there is a risk that polymerization may be insufficient, and if equipment is used to remove oxygen, the apparatus becomes large. Vinyl ether groups and epoxy groups are advantageous in this respect because they are not affected by oxygen inhibition, but the ether bond of vinyl ether groups is unstable and easily cleaved, and epoxy groups are complicated to introduce into liquid crystal materials. In addition, it is difficult to obtain a high degree of polymerization when the crosslinking treatment is performed. Furthermore, in order to obtain homeotropic alignment, a large amount of non-liquid crystalline structural units are introduced into the liquid crystal material, and there is a question about the stable liquid crystallinity. In Patent Document 9, a phase difference plate is obtained in which a homeotropic alignment liquid crystal film and a stretched film having a retardation function are laminated and integrated. The method for producing a homeotropic alignment liquid crystal film is the same as in Patent Document 10 and the like. It is a manufacturing method, and it can be said that a problem remains in the manufacture of a conventional homeotropic alignment film, which is insufficient.

JP 2000-304924 A Japanese Patent No. 2853064 Japanese Patent No. 3018120 Japanese Patent No. 3078948 JP 2002-174725 A JP 2002-333524 A JP 2002-333642 A JP 2003-2927 A JP 2003-149441 A JP 2003-2927 A

  The present invention enables stable production without requiring a complicated process such as light irradiation under an inert gas atmosphere, and is excellent in alignment retention ability and mechanical strength after liquid crystal alignment fixation, and has a thickness. An object of the present invention is to provide an elliptically polarizing plate capable of controlling the direction retardation in a wide range and a manufacturing method thereof. It is another object of the present invention to provide a brightness enhancement film using the elliptically polarizing plate and an image display device using the elliptically polarizing plate and the brightness enhancement film.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the object can be achieved by the elliptical polarizing plate shown below, and have completed the present invention.

  That is, the present invention relates to an elliptically polarizing plate formed by laminating a homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed, a retardation film having a retardation function, and a linear polarizing plate.

  In addition, the present invention provides a liquid crystalline composition in which the homeotropic alignment liquid crystal layer contains at least a side chain type liquid crystalline polymer compound having an oxetanyl group, and then homeotropically aligns the oxetanyl in a liquid crystal state. The elliptically polarizing plate is characterized in that the homeotropic alignment is fixed by reacting a group.

  In the present invention, a liquid crystalline composition containing at least a side chain type liquid crystalline polymer compound having an oxetanyl group is aligned homeotropically in a liquid crystal state on an alignment substrate having homeotropic alignment ability. A phase difference film having a phase difference function is adhered to the homeotropic alignment liquid crystal layer on the alignment substrate on which the homeotropic alignment is fixed by reacting the oxetanyl group, and a homeotropic alignment is applied. The present invention relates to a method for producing an elliptically polarizing plate, wherein a liquid crystal layer is peeled from an alignment substrate, a homeotropic alignment liquid crystal layer and a retardation film having a retardation function are stacked, and then a linear polarizing plate is stacked.

  The present invention also provides a liquid crystalline composition comprising at least a side chain type liquid crystalline polymer compound having an oxetanyl group on a retardation film substrate having homeotropic alignment ability and retardation function in a liquid crystal state. After a homeotropic alignment, a retardation film having a retardation function is laminated on a laminate obtained by reacting the oxetanyl group and fixing the homeotropic alignment, and then using a pressure-sensitive adhesive or an adhesive means. It is related with the manufacturing method of the elliptically polarizing plate characterized by having laminated | stacked.

  Moreover, this invention relates to the elliptically polarizing plate manufactured with the said manufacturing method.

The present invention also relates to the above elliptically polarizing plate, wherein the elliptically polarizing plate satisfies the following [1] to [4].
[1] 0 nm ≦ Re1 ≦ 50 nm
[2] −500 nm ≦ Rth1 ≦ −30 nm
[3] 30 nm ≦ Re2 ≦ 500 nm
[4] 0 nm ≦ Rth2 ≦ 300 nm
(Here, Re1 and Re2 represent in-plane retardation values of the homeotropic alignment liquid crystal layer and retardation film having retardation function, respectively, and Rth1 and Rth2 respectively represent homeotropic alignment liquid crystal layer and retardation function. The Re1, Re2, Rth1, and Rth2 are Re1 = (Nx1-Ny1) × d1 [nm] and Rth1 = (Nx1-Nz1) × d1, respectively. [Nm], Re2 = (Nx2−Ny2) × d2 [nm], Rth2 = (Nx2−Nz2) × d2 [nm], and d1 and d2 are a homeotropic alignment liquid crystal layer and a retardation function, respectively. The thickness of the retardation film Nx1, Ny1 is the main refractive index in the plane of the homeotropic alignment liquid crystal layer, Nx2, Ny, respectively. 2 is the in-plane main refractive index of the retardation film having the retardation function, and Nz1 and Nz2 are the main refractive indices in the thickness direction of the homeotropic alignment liquid crystal layer and the retardation film having the retardation function, respectively. Nz1> Nx1 ≧ Ny1, Nx2> Ny2.)

  In the present invention, at least one cholesteric liquid crystal film is further laminated on the elliptically polarizing plate having an in-plane retardation value (Re2) in the range of 100 to 170 nm of a retardation film having a retardation function. The present invention relates to a brightness enhancement film.

  Furthermore, the present invention relates to an image display device to which the elliptically polarizing plate or the brightness enhancement film is applied.

  By using a liquid crystal material containing a side-chain liquid crystalline polymer substance and fixing the alignment state of the liquid crystal material, the orientation of the homeotropic alignment film with excellent heat resistance, high hardness, and excellent mechanical strength is achieved. An elliptically polarizing plate in which a retardation film having a retardation function and a linear polarizing plate are laminated is obtained, and is useful as an optical film for various liquid crystal display devices, organic EL display devices, PDPs and other image display devices.

Hereinafter, the present invention will be described in detail.
The elliptically polarizing plate of the present invention is a laminate of a homeotropic alignment liquid crystal layer, a retardation film having a retardation function, and a linear polarizing plate. In the present invention, in order to obtain a liquid crystal layer in which the homeotropic alignment of the liquid crystal material is fixed, the selection of the liquid crystal material and the alignment substrate having homeotropic alignment ability is extremely important.

First, the liquid crystal material will be described.
As the liquid crystal material used in the present invention, a material containing a side chain type liquid crystalline polymer such as poly (meth) acrylate or polysiloxane as a main constituent component is preferably used. In the present invention, the side chain type liquid crystal polymer has a terminal polymerizable group such as an acryloyl group, a vinyl group, a vinyloxy group, an epoxy group or an oxetanyl group. Those having an oxetanyl group are preferably used in view of orientation fixing reaction and the like. 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 liquid crystalline polymer substance is preferably used.

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 each independently represent a single bond, —O—, —O. -CO- or -CO-O- is represented, M represents Formula (2), Formula (3) or Formula (4), and n and m each independently represent an integer of 0 to 10.
-P ₁ -L ₃ -P ₂ -L ₄ -P _3- (2)
-P ₁ -L ₃ -P _3- (3)
-P _3- (4)

In Formulas (2) to (4), P ₁ and P ₂ each independently represent a group selected from Formula (5), P ₃ represents a group selected from Formula (6), and L ₃ and L ₄ 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 an ordinary 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.

  The (meth) acrylic group having the oxetanyl group represented by the formula (1) is represented by the following formula (7) by homopolymerizing 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) acrylic 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. The method of making it react at 60-120 degreeC for several hours is mentioned. Moreover, in order to make the liquid crystal phase appear stably, copper bromide (I) / 2,2′-bipyridyl series, 2,2,6,6-tetramethylpiperidinooxy free radical (TEMPO) series, 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) acrylic compound to be copolymerized at this time is not particularly limited and may be anything as long as the synthesized polymer compound exhibits liquid crystallinity, but in order to increase the liquid crystallinity of the synthesized polymer compound, A (meth) acrylic compound having a mesogenic group is preferred. For example, a (meth) acryl compound represented by the following formula (8) can be exemplified as a preferred compound.

  In formula (8), R represents hydrogen, a C1-C12 alkyl group, a C1-C12 alkoxy group, or a cyano group.

  As the side chain type liquid crystalline polymer substance, those containing 5 to 100 mol% of the unit represented by the formula (7) are preferable, and those containing 10 to 100 mol% are particularly preferable. 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 exhibiting 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.

  In addition, since the liquid crystal material is subjected to an alignment treatment, the oxetanyl group is cationically polymerized and crosslinked to cross-link the liquid crystal state. Therefore, the liquid crystal material is subjected to cation by external stimulation such as light or heat. It is preferable to contain a photo cation generator and / or a thermal cation generator that generate a cation, and among them, a photo cation generator is more preferable. 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, sulfonate 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 when 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. Although it cannot be said, it is usually in the range of 100 mass ppm to 20 mass%, preferably 1000 mass ppm to 10 mass%, more preferably 0.2 mass% to 7 mass% with respect to the side chain type liquid crystalline polymer substance. is there. 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, an alignment substrate having homeotropic alignment ability 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, polycycloolefin, ethylene / propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide. A film made of a transparent polymer such as 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, the hydrogen bonding property is high, and plastic films such as triacetyl cellulose, polycarbonate, norbornene polyolefin and the like used as an optical film are awarded. Examples of the organic polymer film include 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 norbornene structure 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 above-mentioned liquid crystal material, the material constituting these substrates has, for example, a long-chain (usually 4 or more carbon atoms, preferably 8 or more) alkyl group. It is preferable that the surface of these substrates has a layer made of the material having the long-chain alkyl group. 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 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 apply 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, a manufacturing process of the homeotropic alignment liquid crystal layer (hereinafter also simply referred to as a liquid crystal layer) of the present invention will be described.
The method for producing the liquid crystal layer is not particularly limited. However, the liquid crystal material is spread on the alignment substrate, and the liquid crystal material is aligned, and then the alignment is performed by light irradiation and / or heat treatment. It can be manufactured by fixing the 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. Mixing system is preferably used. Moreover, 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.
Further, in order to facilitate the fixation of the alignment of the side-chain liquid crystalline polymer material, a group having the same reactivity as the polymerizable group bonded to the side-chain liquid crystal polymer material is added. It is also possible to add a low molecular compound having two or more in one molecule (regardless of liquid crystallinity or non-liquid crystallinity) or various compounds capable of improving adhesiveness.

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.
Although the film thickness of the liquid crystal layer depends on the method of the image display device and various optical parameters, it cannot be generally stated, but is usually 0.2 μm to 10 μm, preferably 0.3 μm to 5 μm, more preferably 0.8 μm. 5 μm to 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 image display device may be unnecessarily colored.

  Subsequently, the liquid crystal material layer formed on the alignment substrate is formed into a liquid crystal alignment 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. As conditions for the heat treatment, the optimum conditions and limit values differ depending on the liquid crystal phase behavior temperature (transition temperature) of the liquid crystal material to be used. The heat treatment is preferably performed at a temperature equal to or higher than the glass transition temperature (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. Moreover, about heat processing time, it is 3 seconds-30 minutes normally, Preferably it is the range of 10 seconds-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 forming the liquid crystal alignment on the liquid crystal material layer by a method such as heat treatment, the liquid crystal material is cured by a polymerization reaction of a polymerization reactive group such as an oxetanyl group 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 polymerization reactive group including a polymerizable oxetanyl group, it is preferable to use a cationic polymerization initiator (cation generator) for the polymerization (crosslinking) of the reactive group. It is as follows.
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 end of the alignment step. 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 significantly different, or when the liquid crystal material itself has the ability to absorb light from the light source. 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 improve 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 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 obtained liquid crystal layer is finally opaque in the intended use wavelength region, or the alignment substrate is too thick, which hinders 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 on a substrate different from the alignment substrate via an adhesive or an adhesive, and then if necessary. Examples thereof include a method of transferring a liquid crystal layer 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 a homeotropic alignment liquid crystal layer, this retardation value is symmetric about the vertical incident axis with respect to the tilted angle.
Several methods can be used for measuring the optical phase difference. For example, an automatic birefringence measuring device (manufactured by Oji Scientific Instruments) and a polarizing microscope can be used. This homeotropic alignment liquid crystal layer appears black between the crossed Nicol polarizers. In this way, homeotropic orientation can be evaluated.

  The homeotropic alignment liquid crystal layer thus obtained has a thickness d1 (μm) = 1 to 10 when the in-plane main refractive indexes are Nx1 and Ny1 and the refractive index in the thickness direction is Nz1. For example, according to the materials described in the examples, (Nx1-Ny1) = 0 to 0.0005, and (Nx1-Nz1) = − 0.1800 to −0.2000. In general, Nx1 = 1.53 to 1.55, Ny1 = 1.53 to 1.55, and Nz1 = 1.72 to 1.74.

  In the homeotropic alignment liquid crystal layer of the present invention, when Nz1> Nx1 ≧ Ny1, the in-plane retardation value (Re1 = (Nx1-Ny1) × d1 [nm]) is 0 to 50 nm, and the retardation in the thickness direction. The foundation value (Rth1 = (Nx1-Nz1) × d1 [nm]) is −500 to −30 nm.

  The Re1 and Rth1 values, which are optical parameters of the homeotropic alignment liquid crystal layer, are used as a viewing angle improving film due to differences in applications such as when used as a brightness enhancement film or as a viewing angle improving film of a liquid crystal display device. In some cases, the retardation value (Re1) in the plane of the homeotropic alignment liquid crystal layer is usually 0 nm for monochromatic light of 550 nm because it depends on the method of the liquid crystal display device and various optical parameters. The retardation value (Rth1) in the thickness direction is usually −500 to −30 nm, preferably −400 to −50 nm, more preferably −50 nm, preferably 0 nm to 20 nm, more preferably 0 nm to 5 nm. Preferably, it is controlled to -400 to -100 nm.

  By setting the Re1 value and the Rth1 value in the above ranges, 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. An improvement effect can be obtained. When the Re1 value is larger than 50 nm, the front characteristics of the liquid crystal display device may be deteriorated due to the large front phase difference value. In addition, when the Rth1 value is larger than −30 nm or smaller than −500 nm, a sufficient viewing angle improvement effect cannot be obtained, or unnecessary coloring may occur when viewed from an oblique direction.

Next, a retardation film having a retardation function will be described.
Examples of the retardation film having a retardation function include a film obtained by uniaxially stretching or biaxially stretching a polymer film, a coating film of a liquid crystalline polymer, and a film subjected to a Z-axis alignment treatment.
Among the retardation films, the polymer film that performs uniaxial stretching or biaxial stretching preferably has a smooth plane and high transmittance, and examples thereof include films and sheets made of organic polymer materials. For example, 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, polycarbonate polymers, polymethyl methacrylate And a film made of a transparent polymer such as an acrylic polymer. Also, styrene polymers such as polystyrene, acrylonitrile / styrene copolymer, olefin polymers such as polyethylene, polypropylene, polycycloolefin, ethylene / propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide. A film made of a transparent polymer such as 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, the hydrogen bonding property is high, and plastic films such as triacetyl cellulose, polycarbonate, and polycycloolefin that are used as optical films are awarded. Examples of the organic polymer film include 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 norbornene structure is preferably used. A retardation film formed by stretching the above film has optically excellent characteristics.

  An alignment film made of a liquid crystal material such as a liquid crystal polymer is on a substrate or a substrate coated with an alignment film that exhibits a uniform and monodomain nematic alignment and can easily fix the alignment state. The film is then heat-treated to form a uniform, monodomain nematic structure and then cooled to be fixed without impairing the alignment in the liquid crystal state. The liquid crystal polymer can also be used as a liquid crystal composition by blending a photopolymerizable liquid crystal compound. Since the liquid crystal polymer containing the photopolymerizable liquid crystal compound can form a film on a substrate or a substrate coated with an alignment film having nematic alignment ability, the Tg of the liquid crystal film can be designed to be low. In order to improve the durability that can be used for applications such as a liquid crystal display for these liquid crystal films, it is preferable to use a nematic alignment liquid crystalline composition containing a photopolymerizable liquid crystal compound. The nematic alignment liquid crystalline composition is irradiated with light such as ultraviolet rays after being aligned.

  When the in-plane main refractive index is Nx2, Ny2, the refractive index in the thickness direction is Nz2, and Nx2> Ny2, the stretched film has a thickness d2 (μm) = about 25-30 For example, according to the materials described in the examples, materials having (Nx2-Ny2) = 0.040 to 0.0060 and (Nx2-Nz2) = 0.040 to 0.0060 are used. In general, Nx2 is about 1.5930 to 1.5942, Ny2 is about 1.5850 to 1.5887, and Nz2 is about 1.5850 to 1.5883.

  In the stretched film having a retardation function in the present invention, when Nx2> Ny2, the in-plane retardation value (Re2 = (Nx2-Ny2) × d2 [nm]) is 30 to 500 nm, and the retardation in the thickness direction. The foundation value (Rth2 = (Nx2-Nz2) × d2 [nm]) is 0 to 300 nm.

  Re2 value and Rth2 value, which are optical parameters of stretched film with retardation function, are used for viewing angle improving film when used as brightness enhancing film, when used as viewing angle improving film for liquid crystal display device, etc. In this case, since it depends on the method of the liquid crystal display device and various optical parameters, it cannot be said unconditionally, but for a monochromatic light of 550 nm, the in-plane retardation value (Re2) is usually 30 nm to 500 nm, Preferably, it is in the range of 50 nm to 400 nm, more preferably in the range of 100 nm to 300 nm, and the retardation value (Rth2) in the thickness direction is usually controlled to 0 to 300 nm, preferably 0 to 200 nm, more preferably 0 to 150 nm. It has been done.

  By setting the Re2 value and the Rth2 value in the above ranges, 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. An improvement effect can be obtained. When the Re2 value is smaller than 30 nm or larger than 500 nm, a sufficient viewing angle improvement effect cannot be obtained, or unnecessary coloring may occur when viewed from an oblique direction. Further, when the Rth2 value is smaller than 0 nm or larger than 300 nm, a sufficient viewing angle improvement effect cannot be obtained, or unnecessary coloring may occur when viewed from an oblique direction.

  The elliptically polarizing plate of the present invention can be produced, for example, by producing a homeotropic alignment liquid crystal layer using a retardation film having a homeotropic alignment ability and a retardation function as a substrate, and on an alignment substrate having a homeotropic alignment ability. The prepared homeotropic alignment liquid crystal layer is laminated on a retardation film having a retardation function through a layer of a pressure-sensitive adhesive or an adhesive (hereinafter referred to as an adhesive / adhesive), or the alignment substrate is peeled off after lamination. Then, it is obtained by laminating a later-described linear polarizing plate on a laminated retardation plate obtained by transferring to a retardation film having a retardation function.

Hereinafter, the linear polarizing plate will be described.
The linearly polarizing plate usually has a protective film on one side or both sides of the polarizer. The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymers such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. Examples thereof include polyene-based oriented films such as those obtained by adsorbing volatile substances 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 solution of iodine and stretching it 3 to 7 times the original length. Moreover, it can also be immersed in aqueous solutions, such as a boric acid and potassium iodide, as needed. 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, polycycloolefin, ethylene / propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers Polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or blends of the above polymers Are examples of polymers that form protective films. Other examples include films made of thermosetting or ultraviolet curable resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone. Generally the thickness of a protective film is 500 micrometers or less, and 1-300 micrometers is preferable. In particular, the thickness is preferably 5 to 200 μm.

  As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. 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 via 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.
The hard coat treatment is performed for the purpose of preventing scratches on the polarizing plate surface, for example, a protective film with a cured film excellent in hardness, sliding properties, etc., by an appropriate ultraviolet curable resin such as acrylic or silicone. It can be formed by a method of adding to the surface of the film. 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. In addition, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

  The anti-glare treatment is performed for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, a rough surface by a sandblasting method or an embossing method. 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 conversion method or a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include a conductive material made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, or the like having an average particle diameter of 0.5 to 50 μm. Transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, etc. may be used. When 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 linearly polarizing plate can be used as an elliptically polarizing plate or a circularly polarizing plate in which retardation plates are laminated. The elliptically polarizing plate or the circularly polarizing plate changes linearly polarized light to elliptically polarized light or circularly polarized light, changes elliptically polarized light or circularly polarized light to linearly polarized light, or changes the polarization direction of the linearly polarized light by the retardation plate. In particular, a so-called quarter-wave plate is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. The half-wave plate is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black-and-white display without coloring by compensating (preventing) the coloring (blue or yellow) caused by the birefringence of the liquid crystal layer of the Spirsist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which the image is displayed in color, and also has an antireflection function.

In addition to the lamination method for obtaining the elliptically polarizing plate of the present invention, a linear polarizing plate and a retardation film having a retardation function are laminated, or the retardation film is transferred to the linear polarizing plate side, and then homeotropic alignment is performed. A method of laminating or transferring a homeotropic alignment liquid crystal layer in which is fixed is also used.
At that time, as a method of laminating a linearly polarizing plate in which a protective film is laminated on both sides of the polarizer and a phase difference film having a phase difference function, for example, both are directly laminated using an adhesive or an adhesive described later. A method of providing a liquid crystal polymer that has a nematic alignment ability on a linearly polarizing plate, shows a uniform monodomain nematic alignment, and can easily fix the alignment state by means such as coating. A method of transferring a nematic liquid crystal compound provided on a film substrate to a protective film of a linearly polarizing plate using an adhesive or an adhesive described later is suitably used.

  The elliptically polarizing plate of the present invention is an elliptically polarizing plate in which a homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed, a retardation film having a retardation function, and a linear polarizing plate are stacked, but the stacked configuration is limited to that. Any of the following configurations (1) to (3) may be used.

(1) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed / positive uniaxial optically anisotropic layer having retardation in the film plane / film thickness Negative uniaxial optically anisotropic layer having phase difference in direction

(2) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer with fixed homeotropic alignment / negative biaxial optically anisotropic layer

(3) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed / positive uniaxial optical anisotropic layer having retardation in the film plane

Moreover, members, such as a light-diffusion layer, a light control film, a light-guide plate, a prism sheet, are further added as needed.
As a liquid crystal display device, a homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed, a retardation film having a retardation function, and a straight line are described in terms of obtaining optical characteristics with less viewing angle dependency. In addition to the structure in which a polarizing plate is laminated, any of the following configurations (4) to (9) may be used.

(4) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed / positive uniaxial optical anisotropic layer having retardation in the film plane / film thickness Negative uniaxial optically anisotropic layer having retardation in direction / vertical alignment liquid crystal cell / positive uniaxial optically anisotropic layer having retardation in film plane / linear polarizing plate / backlight

(5) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed / positive uniaxial optical anisotropic layer having retardation in the film plane / film thickness Negative uniaxial optically anisotropic layer having phase difference in direction / vertical alignment liquid crystal cell / negative uniaxial optically anisotropic layer having phase difference in film thickness direction / positive having phase difference in film plane Uniaxial optically anisotropic layer / linear polarizing plate / backlight

(6) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer with fixed homeotropic alignment / positive uniaxial optical anisotropic layer having retardation in the film plane / vertical alignment Liquid crystal cell / negative uniaxial optical anisotropic layer having retardation in film thickness direction / positive uniaxial optical anisotropic layer having retardation in film plane / linear polarizing plate / backlight

(7) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer with fixed homeotropic alignment / negative biaxial optical anisotropic layer / vertical alignment liquid crystal cell / position in the film plane Positive uniaxial optically anisotropic layer having phase difference / linear polarizing plate / backlight

(8) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer with fixed homeotropic alignment / negative biaxial optical anisotropic layer / vertical alignment liquid crystal cell / negative biaxiality Optically anisotropic layer / Linear polarizing plate / Backlight

(9) Linearly polarizing plate / retardation film having retardation function / homeotropic alignment liquid crystal layer with fixed homeotropic alignment / positive uniaxial optical anisotropic layer having retardation in the film plane / vertical alignment Liquid crystal cell / Negative biaxial optical anisotropic layer / Linear polarizing plate / Backlight

  When the x and y directions are taken in the in-plane direction and the thickness direction is the z direction, the positive uniaxial optically anisotropic 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.

  Further, among the optically anisotropic layers described in (1) to (6) above, a positive uniaxial optically anisotropic layer having a retardation in a film plane not adjacent to the linearly polarizing plate of (1) And (2) a negative biaxial optically anisotropic layer, (3) a positive uniaxial optically anisotropic layer having a phase difference in the film plane not adjacent to the linearly polarizing plate, (4) ) To (6), or a positive uniaxial optically anisotropic layer having a retardation in the plane of the film adjacent to the negative uniaxial optically anisotropic layer, and (7) It is preferable that the negative biaxial optically anisotropic layer of (9) shows a phase difference of ¼ wavelength in the plane.

  In addition, the optical retardation layer (Re) in the plane of the optically anisotropic layer with respect to light having a wavelength of 550 nm is expressed in that each optically anisotropic layer exhibits a quarter wavelength retardation. The range is 100 nm to 180 nm, preferably 120 nm to 160 nm, and more preferably 130 nm to 150 nm. When outside the above range, sufficient circular polarization when combined with the polarizing plate cannot be obtained, and the display characteristics when viewed from the front may be deteriorated.

  Further, the thickness of the negative biaxial optical anisotropic layer (2), (7) to (9) is d3, the in-plane main refractive index is Nx3, Ny3, and the refractive index in the thickness direction is Nz3. And Nx3> Ny3> Nz3, the retardation value in the thickness direction (Rth3 = (Nx3-Nz3) × d3 [nm]) compensates for the thickness direction retardation of the vertical alignment type liquid crystal cell. It is necessary to set conditions so that the viewing angle compensation effect can be exhibited. Therefore, although depending on the retardation value in the thickness direction of the vertical alignment type liquid crystal cell, it is in the range of 50 nm to 600 nm, preferably 100 nm to 400 nm, and more preferably 200 nm to 300 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.

Each optically anisotropic layer described in the above (1) to (9) will be described.
First, as a positive uniaxial optically anisotropic layer having a retardation function in the film plane, for example, a polymer film uniaxially or biaxially stretched, a liquid crystalline polymer coating film, a Z-axis alignment treatment And the like.

  The polymer film that performs uniaxial stretching or biaxial stretching preferably has a smooth plane and high transmittance, and examples thereof include films and sheets made of organic polymer materials, such as polyvinyl alcohol and polyimide. , Polyester polymers such as polyphenylene oxide, polyether ketone, polyether ether ketone, polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, acrylic polymers such as polymethyl methacrylate, etc. And a film made of a transparent polymer. Also, styrene polymers such as polystyrene, acrylonitrile / styrene copolymer, olefin polymers such as polyethylene, polypropylene, polycycloolefin, ethylene / propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide. A film made of a transparent polymer such as 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, and polycycloolefin that are used as optical films are used. Examples of the organic polymer film include 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 cyclic structure is preferably used. A retardation film produced by a method of uniaxially or biaxially stretching the above-described film, a method of reducing the retardation in the stretching direction by a heat shrink film as disclosed in JP-A-5-157911, and The polymer film described in 2001-343529 (WO01 / 37007) has optically excellent characteristics. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be, for example, an extruded product of the resin composition.

  As a liquid crystalline polymer coating film, a liquid crystalline polymer that exhibits uniform and monodomain nematic alignment and can easily fix the alignment state is heat-treated on a substrate or a substrate coated with an alignment film. In addition, a uniform, monodomain nematic structure is formed and then cooled to be fixed without impairing the alignment in the liquid crystal state. The liquid crystal polymer can also be used as a liquid crystal composition by blending a photopolymerizable liquid crystal compound. Since the liquid crystal polymer containing the photopolymerizable liquid crystal compound can form a film on a substrate or a substrate coated with an alignment film having nematic alignment ability, the Tg of the liquid crystal film can be designed to be low. In order to improve the durability that can be used for applications such as a liquid crystal display for these liquid crystal films, it is preferable to use a nematic alignment liquid crystalline composition containing a photopolymerizable liquid crystal compound. The nematic alignment liquid crystalline composition is irradiated with light such as ultraviolet rays after being aligned.

  Next, the negative uniaxial optically anisotropic layer having a retardation in the film thickness direction is not particularly limited, but as a non-liquid crystal material, it has excellent heat resistance, chemical resistance, transparency, and rigidity. For example, polycycloolefins such as cellulose triacylate, ZEONEX, ZEONOR (both manufactured by Nippon Zeon Co., Ltd.), ARTON (manufactured by JSR Co., Ltd.), polyamide, polyimide, polyester, polyether ketone, Polymers such as polyaryletherketone, polyamideimide, and polyesterimide are preferred. Any one kind of these polymers may be used alone, or a mixture of two or more kinds having different functional groups, such as a mixture of polyaryletherketone and polyamide. Among such polymers, polyimide is particularly preferable because of its high transparency and high orientation. As the polyimide, for example, a polyimide that has high in-plane orientation and is soluble in an organic solvent is preferable. Specifically, for example, a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and aromatic tetracarboxylic dianhydride disclosed in JP-T-2000-511296, specifically, A polymer containing one or more repeating units represented by the following formula (9) can be used.

  Specifically, for example, a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and aromatic tetracarboxylic dianhydride disclosed in JP-T-2000-511296, specifically, A polymer containing one or more repeating units represented by the following formula (9) can be used.

In the formula ^(9), R 3 ~R ⁶ is hydrogen, halogen, a phenyl group, 1-4 halogen atoms, or _C 1 _{~ 10} alkyl-substituted phenyl, and _C 1 _{~ 10} alkyl group And at least one substituent selected independently from the group. ^Preferably, R 3 to R ⁶ is a halogen, a phenyl group, each independently from the group consisting of one to four halogen atoms or _C 1 _{~ 10} alkyl-substituted phenyl, and _C 1 _{~ 10} alkyl group It is at least one type of substituent selected.
In the formula (9), Z is, for example, a tetravalent aromatic group having C ₆ ~ _20, preferably a pyromellitic group, a polycyclic aromatic group, a derivative of a polycyclic aromatic group, or, It is group represented by following formula (10).

In the formula (10), Z ′ is, for example, a covalent bond, C (R ⁷ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, or NR ^Eight groups, and in the case of a plurality, they may be the same or different. W represents an integer from 1 to 10. Each R ⁷ is independently hydrogen or C (R ⁹ ) ₃ . R ⁸ is hydrogen, an alkyl group having 1 to 20 carbon atoms, or a C ₆ to ₂₀ aryl group, and in a plurality of cases, they may be the same or different. R ⁹ is independently hydrogen, fluorine, or chlorine.

Examples of the liquid crystal material include a cholesteric alignment film made of a liquid crystal material such as a cholesteric liquid crystalline polymer, a film in which a cholesteric alignment layer of the liquid crystal material is supported by a film, a discotic liquid crystal layer, and the like. First, the cholesteric oriented film preferably has a uniform planar orientation in which the cholesteric helical axis exists in the normal direction of the film by a method such as heat treatment, and the selective reflection wavelength λ _s is in the range of 300 nm or less. Is preferred.

In addition, the material for realizing cholesteric alignment is not limited to a liquid crystalline polymer, and liquid crystal monomer molecules having a polymerizable group capable of realizing cholesteric alignment alone, or a mixture of a liquid crystalline monomer having a polymerizable group and a chiral compound, etc. Preferably used. After these materials are cholesterically oriented by a method selected appropriately such as heat treatment, the polymerizable group can be cured by a suitably used means such as heat or light, and the cholesteric orientation can be fixed and used.
Further, as a liquid crystal material other than the above that forms the negative uniaxial optically anisotropic layer, a polymerizable discotic liquid crystal compound that is homeotropically aligned is also preferably used.

The negative uniaxial optically anisotropic layer having a retardation in the film thickness direction is negative uniaxial in that it compensates the viewing angle of the vertically aligned liquid crystal layer of the vertically aligned liquid crystal cell in the liquid crystal display element. The thickness of the optically anisotropic layer is d, the main refractive index in the negative uniaxial optically anisotropic layer surface is Nx and Ny, the main refractive index in the thickness direction is Nz, and Nx ≧ Ny> Nz. , In-plane retardation value (Re = (Nx−Ny) × d [nm]) in the wavelength 550 nm light, thickness direction retardation value (Rth = {(Nx + Ny) / 2−Nz} × d [nm ]) Satisfying the following formulas [5] and [6] are preferable.
[5] 0 ≦ Re ≦ 20
[6] 100 ≦ Rth ≦ 400

Although the negative uniaxial optically anisotropic layer depends on the optical film thickness of the vertically aligned liquid crystal cell and the birefringence value Δn of the liquid crystal material used in the vertically aligned liquid crystal cell, it cannot be generally stated, but negative 1 The retardation value (Re) in the plane of the axial optically anisotropic layer is usually in the range of 0 nm to 20 nm, preferably 0 nm to 10 nm, more preferably 0 nm to 5 nm. When the Re value is out of the above range, there is a risk of a decrease in contrast when viewed from the front. The retardation value (Rth) in the thickness direction of the negative uniaxial optically anisotropic layer is usually 100 to 400 nm because the retardation value in the thickness direction of the vertical alignment type liquid crystal cell is usually 100 to 400 nm. In the case of only, it is 150 nm-400 nm, Preferably it is 180 nm-360 nm, More preferably, it is the range of 200 nm-300 nm. When two negative uniaxial optically anisotropic layers are used in combination, the total Re value is usually in the range of 150 to 400 nm, preferably 180 to 360 nm, more preferably 200 to 300 nm. When viewed with an optically anisotropic layer, the thickness is usually 75 to 200 nm, preferably 90 to 180 nm, and more preferably 100 to 150 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.
Examples of the negative biaxial optically anisotropic layer include those obtained by uniaxially or biaxially stretching a polymer film, a coating film of a liquid crystalline polymer, and a Z-axis aligned treatment.

  As a polymer film which performs uniaxial stretching or biaxial stretching, a polymer film having a smooth plane and high transmittance is preferable, and examples thereof include films and sheets made of organic polymer materials. For example, 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, polycarbonate polymers, polymethyl methacrylate And a film made of a transparent polymer such as an acrylic polymer. Also, styrene polymers such as polystyrene, acrylonitrile / styrene copolymer, olefin polymers such as polyethylene, polypropylene, polycycloolefin, ethylene / propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide. A film made of a transparent polymer such as 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, and polycycloolefin that are used as optical films are used. Examples of the organic polymer film include 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 cyclic structure is preferably used. A retardation film produced by a method of uniaxially or biaxially stretching the above-described film, a method of reducing the retardation in the stretching direction by a heat shrink film as disclosed in JP-A-5-157911, and The polymer film described in 2001-343529 (WO01 / 37007) has optically excellent characteristics. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be, for example, an extruded product of the resin composition.

Examples of the liquid crystal polymer include main chain type liquid crystalline polymer compounds such as polyimide, polyamide, polyester, polyether, polycarbonate, polyesterimide, and polythioether. Among the main chain type liquid crystalline polymer compounds, polyimide and polyester are preferably used because of their ease of synthesis. Furthermore, a liquid crystalline polymer compound showing a liquid crystal layer including an S _CA phase (smectic CA phase) is also preferably used as the negative biaxial optically anisotropic layer. As a specific example of the liquid crystalline polymer compound, a main chain type liquid crystal in which a mesogenic portion formed from an aromatic group having high linearity and a bent chain portion formed from an aliphatic chain are alternately bonded. Can be mentioned. Representative examples of the structure of the mesogen moiety include biphenyl and terphenyl. The bent chain portion is typically a linear aliphatic group, and in particular, those having an odd number of atoms in the main chain are desirably used.

The biaxial optically anisotropic layer can also be formed by stretching a film in which the polymer liquid crystal is oriented. The forming step for forming a film and the alignment forming step can be performed simultaneously or separately. For example, it is possible to obtain a liquid crystal layer structure (alignment structure) including an _SCA phase at the same time as forming a film by stretching the liquid crystalline polymer in an isotropic state. On the other hand, after forming into a film by an appropriate method, the film-formed product may be transferred to an isotropic state and then stretched. In this case, there is no restriction | limiting in particular in the shaping | molding method of film formation, Well-known methods, such as a casting method, a melt extrusion method, and a rolling method, can be used.

  The adhesive / adhesive forming the adhesive / adhesive layer used for laminating and transferring each film is not particularly limited as long as it is optically isotropic and transparent. For example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as a base polymer can be appropriately selected and used. Moreover, the reactive thing which reacts by external stimuli, such as light, an electron beam, and heat | fever, and superpose | polymerizes or bridge | crosslinks can also be used. Among these, those having excellent optical transparency such as acrylic pressure-sensitive adhesive, moderate wettability, cohesiveness and adhesive properties, and excellent weather resistance and heat resistance are preferably used.

  The formation of the adhesive / adhesive layer can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by mass 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 of attaching it directly on the liquid crystal layer by an appropriate spreading method such as casting or coating, or forming a sticky / adhesive layer on the separator according to the above and transferring it onto the liquid crystal layer Examples include methods. The adhesive / adhesive layer includes, for example, natural and synthetic resins, in particular, tackifier resins, fillers made of glass fibers, glass beads, metal powders, other inorganic powders, and pigments. Various additives that can be added to the adhesive / adhesive layer such as a colorant and an antioxidant may be contained. Further, it may be an adhesive / adhesive layer containing fine particles and exhibiting light diffusibility.

  The thickness of the adhesive / adhesive layer is not particularly limited as long as the member to be adhered can be adhered and sufficient adhesion can be maintained. Can be selected. In view of the strong demand for reduction in the total thickness of the elliptically polarizing plate, the thickness of the adhesive / adhesive is preferably thin, but is usually 2 to 80 μm, preferably 5 to 50 μm, and more preferably 10 to 40 μm. Outside this range, it is not preferable because the adhesive force is insufficient, or it oozes out from the end portion during lamination or storage of the elliptically polarizing plate.

  In addition, when transferring the homeotropic alignment liquid crystal film to the retardation film or the optically anisotropic layer through the adhesive / adhesive layer, the following (A) to (C) are performed so that the transfer is easy. Various processes can be used as appropriate.

(A) A homeotropic alignment liquid crystal layer with a fixed liquid crystal alignment formed on an alignment substrate is directly attached to a retardation film or an optically anisotropic layer via an adhesive layer 1, and the alignment substrate is peeled off. Then, the homeotropic alignment liquid crystal layer is transferred to the retardation film or the optically anisotropic layer.

(B) After the homeotropic alignment liquid crystal layer formed on the alignment substrate, on which the liquid crystal alignment is fixed, is adhered to the re-peelable substrate 1 through the adhesive layer 1, the alignment substrate is peeled to remove the homeotropic layer. The alignment liquid crystal layer is transferred to the releasable substrate 1 to produce an intermediate 1 composed of the releasable substrate 1 / adhesive layer 1 / homeotropic alignment liquid crystal layer, and the releasable substrate via the adhesive layer 2 2 is peeled off, then the releasable substrate 1 is peeled off to produce an intermediate 2 composed of adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 / removable substrate 2, and further an adhesive layer After pasting a non-carrier paste with a separate film on one side, the separate film is peeled off and appropriately stuck to a retardation film or an optically anisotropic layer, and the releasable substrate 2 is peeled off.

(C) After the homeotropic alignment liquid crystal layer formed on the alignment substrate, on which the liquid crystal alignment is fixed, is adhered to the removable substrate 1 through the adhesive layer 1, the alignment substrate is peeled to remove the homeotropic layer. The alignment liquid crystal layer is transferred to the releasable substrate 1 to produce an intermediate 1 composed of the releasable substrate 1 / adhesive layer 1 / homeotropic alignment liquid crystal layer, and the releasable substrate via the adhesive layer 2 2 is peeled off, then the releasable substrate 1 is peeled off to produce an intermediate 2 composed of adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 / removable substrate 2, and further an adhesive layer After pasting a non-carrier paste with a separate film on one side, the releasable substrate 2 is peeled off and an intermediate comprising a separate film / adhesive layer / adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 3 and further adhesive layer 2 A non-carrier paste with a separate film is also bonded to the side to produce an intermediate 4 comprising a separate film / adhesive layer / adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 / adhesive layer / separate film. Then, the separate film is peeled off and attached to the retardation film or the optically anisotropic layer as appropriate.

  Furthermore, by adding an additive such as a surface modifier as appropriate to the adhesive, the adhesion between the releasable substrate and the homeotropic alignment liquid crystal layer can be reduced and bonded to the releasable substrate. By maintaining the adhesive force with the agent layer, the adhesive layer can be peeled off while adhering to the releasable substrate side. There are no particular restrictions on the type and amount of additive used in this case as long as they do not adversely affect the inspection and releasability of optical defects. When transferring to the retardation film or the optically anisotropic layer by such a method, processes such as the following (D) and (E) can be appropriately used so that the transfer is easy.

(D) After the homeotropic alignment liquid crystal layer formed on the alignment substrate, on which the liquid crystal alignment is fixed, is adhered to the removable substrate 1 through the adhesive layer 1, the alignment substrate is peeled to remove the homeotropic layer. The alignment liquid crystal layer is transferred to the releasable substrate 1 to produce an intermediate 1 composed of the releasable substrate 1 / adhesive layer 1 / homeotropic alignment liquid crystal layer, and the releasable substrate via the adhesive layer 2 2 is peeled off, then the releasable substrate 1 is peeled off to produce an intermediate 2 composed of adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 / removable substrate 2, and further an adhesive layer After pasting a non-carrier paste with a separate film on one side, the separate film was peeled off and appropriately stuck to a retardation film or an optically anisotropic layer, and the releasable substrate 2 was stuck to the adhesive layer 2. Peel in state.

(E) After the homeotropic alignment liquid crystal layer formed on the alignment substrate and having the liquid crystal alignment fixed thereto is adhered to the removable substrate 1 through the adhesive layer 1, the alignment substrate is peeled to remove the homeotropic layer. The alignment liquid crystal layer is transferred to the releasable substrate 1 to produce an intermediate 1 composed of the releasable substrate 1 / adhesive layer 1 / homeotropic alignment liquid crystal layer, and the releasable substrate via the adhesive layer 2 2 is peeled off, then the releasable substrate 1 is peeled off to produce an intermediate 2 composed of adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 / removable substrate 2, and further an adhesive layer After pasting a non-carrier paste with a separate film on one side, the releasable substrate 2 is peeled off with the adhesive layer 2 adhered, and a separate film / adhesive layer / adhesive layer 1 / homeotropic alignment liquid crystal. An intermediate 5 consisting of layers is prepared and In addition, a non-carrier adhesive with a separate film is also bonded to the homeotropic alignment liquid crystal layer side to separate film / adhesive layer / adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 / adhesive layer / separate film. An intermediate body 6 is prepared, and the separate film is peeled off and appropriately attached to a retardation film or an optically anisotropic layer.

  When transferring the homeotropic alignment liquid crystal layer to the retardation film having a retardation function or the optically anisotropic layer via the adhesive / adhesive layer, the surface of the homeotropic alignment liquid crystal layer is subjected to surface treatment to obtain a viscosity. -The adhesiveness with the 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 the liquid crystal layer surface can be suitably employed. Among these surface treatment methods, corona discharge treatment is good.

  Furthermore, the above-mentioned liquid crystal material was developed on a phase difference film or an optically anisotropic layer having a homeotropic alignment ability without aligning the homeotropic alignment liquid crystal film with an adhesive / adhesive layer, and the liquid crystal material was aligned. Then, it can also manufacture by fixing the said orientation state by light irradiation and / or heat processing. If necessary, an alignment film having homeotropic alignment ability was placed on the retardation film or optically anisotropic layer, and then the liquid crystal material was developed on the alignment film to align the liquid crystal material. Then, it can also manufacture by fixing the said orientation state by light irradiation and / or heat processing.

As the retardation plate (retardation film), for example, various wavelength plates and those for the purpose of compensating for coloring or viewing angle due to birefringence of the liquid crystal layer can be used, and an appropriate one according to the purpose of use can be used. Two or more retardation plates having a phase difference can be laminated to control optical characteristics such as phase difference. In addition to the above-mentioned examples of the retardation plate, the homeotropic alignment liquid crystal film used in the present invention can be used alone or in combination with other films to obtain the elliptically polarizing plate of the present invention. .
Further, the retardation plate may be used as a viewing angle compensation film, and the viewing angle compensation film has a relatively clear image even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. It is a film to widen the viewing angle so that it can be seen.

  As such a retardation plate for viewing angle compensation, there are a birefringent film such as a uniaxial or biaxial stretching treatment or a biaxial stretching treatment, a bi-directional stretched film such as a tilted orientation film, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, or a film obtained by obliquely aligning a liquid crystal polymer. Is mentioned. The viewing angle compensation film can be appropriately combined for the purpose of preventing coloring or the like due to a change in viewing angle based on a phase difference caused by a liquid crystal cell or increasing the viewing angle for good viewing.

  In addition, the liquid crystal polymer alignment layer, especially the optically anisotropic layer composed of the tilted alignment layer made of discotic liquid crystal polymer or rod-like liquid crystal polymer, is made of triacetyl cellulose film in order to achieve a wide viewing angle with good visibility. A supported optical compensation phase difference plate can be preferably used. In addition to the above, the optical layer laminated in practical use is not particularly limited. For example, one or more optical layers that may be used for forming a liquid crystal display device such as a reflective plate or a transflective plate are used. be able to.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer, if necessary.

Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor-deposited film made of a reflective metal such as aluminum on one side of a protective film matted as necessary. Moreover, what has microparticles | fine-particles contained in the said protective film to make a surface fine concavo-convex structure, and has the reflection layer of a fine concavo-convex structure on it, etc. are mentioned. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. Moreover, the protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the protective film is formed by transparent the metal by an appropriate method such as a vapor deposition method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of directly attaching to the surface of the protective layer.
The reflective plate can be used as a reflective sheet in which a reflective layer is provided on an appropriate film according to the transparent film, instead of the method of directly imparting to the protective film of the polarizing plate. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a protective film, a polarizing plate or the like is used to prevent a decrease in reflectance due to oxidation, and thus the long-term sustainability of the initial reflectance. More preferable is the point of avoiding the additional attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell. When a liquid crystal display device or the like is used in a relatively bright atmosphere, it reflects incident light from the viewing side (display side) to display an image. In a relatively dark atmosphere, a liquid crystal display device that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

Next, a brightness enhancement film in which a cholesteric liquid crystal film is laminated on the elliptically polarizing plate of the present invention will be described.
The brightness enhancement film of the present invention includes a linearly polarizing plate, an elliptically polarizing plate in which a retardation film having a retardation function in which Re2 is in the range of 100 to 170 nm, a homeotropic alignment liquid crystal layer, and a cholesteric liquid crystal film. It is obtained by stacking and has a significant brightness enhancement function.

As the cholesteric liquid crystal film, various films used for conventional brightness enhancement films can be used without particular limitation. A cholesteric liquid crystal film is a characteristic that reflects either left-handed or right-handed circularly polarized light and transmits other light, such as an oriented film of a cholesteric liquid-crystal polymer or a film substrate on which the oriented liquid-crystal layer is supported. The thing which shows is mentioned. As the cholesteric liquid crystal film, for example, a film exhibiting circular dichroism in at least a partial band of visible light or a film exhibiting circular dichroism in a band of 200 nm or more of visible light is used. The cholesteric liquid crystal film can be formed of a cholesteric liquid crystal polymer containing an optically active group-containing monomer as a monomer unit. Since the pitch of the cholesteric liquid crystal changes based on the content of the monomer unit containing the optically active group, the circular dichroism can be controlled by the content of the monomer unit. The thickness of the cholesteric liquid crystal film is usually preferably from 0.5 to 30 μm, particularly preferably from 2 to 15 μm. The cholesteric liquid crystal film may contain a polymer other than the liquid crystal polymer, a compound such as a stabilizer and a plasticizer, and one or more additives such as a metal and a compound thereof as necessary.
A cholesteric liquid crystal film can be obtained by reflecting circularly polarized light in a wide wavelength range such as a visible light region by combining two or more layers with different reflection wavelengths in combination. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  The brightness enhancement film of the present invention is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, light from a light source such as a backlight is incident to obtain transmitted light in a predetermined polarization state, and light other than the predetermined polarization state is reflected without being transmitted. The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer.

  That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

The elliptically polarizing plate and the brightness enhancement film of the present invention can be provided with a pressure-sensitive adhesive layer. The adhesive / adhesive layer can be used for adhering to a liquid crystal cell, and can also be used for laminating other optical films such as the above-described retardation plates and retardation films. When adhering the optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.
The adhesive / adhesive forming the adhesive / adhesive layer is not particularly limited, and examples thereof include the same ones used for bonding the homeotropic alignment liquid crystal layer and the translucent film. Moreover, it can provide by the same system.
The adhesive / adhesive layer may be provided on one side or both sides of a polarizing plate or an optical film as an overlapping layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive / adhesive layers, such as a different composition, a kind, and thickness, in the front and back of a polarizing plate or an optical film. The thickness of the adhesive / adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

  On the exposed surface of the adhesive / adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesive / adhesive layer in a usual handling state. As the separator, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, nonwoven fabric, net, foamed sheet, metal foil, and laminate thereof, if necessary, silicone-based, long-chain alkyl-based, Appropriate ones according to the prior art such as those coated with an appropriate release agent such as fluorine-based or molybdenum sulfide can be used.

  In the present invention, the polarizer, transparent protective film, optical film, and the like that form the polarizing plate described above, and each layer such as the adhesive / adhesive layer include, for example, a salicylic acid ester compound, a benzophenol compound, and a benzotriazole compound. In addition, those having ultraviolet absorbing ability may be used by a method such as a method of treating with an ultraviolet absorber such as a cyanoacrylate compound or a nickel complex salt compound.

The elliptically polarizing plate and the brightness enhancement film of the present invention can be preferably used for forming various devices such as a liquid crystal display device, and are particularly preferably used as a viewing angle improving film for a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, an optical film, and, if necessary, a lighting system and incorporating a drive circuit. There is no limitation in particular except for using a product and a brightness improvement film, and it can be based on the conventional one.
Although there is no restriction | limiting in particular as a liquid crystal display device, Various liquid crystal display devices of a transmissive type, a reflective type, and a semi-transmissive type can be mentioned. Examples of modes by liquid crystal alignment in a liquid crystal cell include TN type, STN type, VA (vertical alignment) type, MVA (multi-domain vertical alignment) type, OCB (optically compensated bend) type, ECB (electrically controlled birefringence). Type, HAN (hybrid-aligned nematic) type, IPS (in-plane switching) type, bistable nematic (Bistable Nematic) type, ASM (Axially Symmetric Aligned Microcell) type, halftone grayscale type, ferroelectric liquid crystal, anti-strong A display method using dielectric liquid crystal can be used.
The liquid crystal alignment may have a single direction in the plane of the cell, or may be used for a liquid crystal display device in which the alignment is divided. Further, in terms of a method of applying a voltage to the liquid crystal cell, for example, a liquid crystal display device driven by a passive method using an ITO electrode or the like, an active method using a TFT (thin film transistor) electrode, a TFD (thin film diode) electrode, or the like. be able to.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film can be installed on one side or both sides of the liquid crystal cell. When providing a polarizing plate and an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer of an appropriate part such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight at an appropriate position. Alternatively, two or more layers can be arranged.

Next, an organic electroluminescence device (organic EL display device) will be described.
Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In the organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and usually a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is used. Used as the anode. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .
That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .
This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

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-GEL SuperH1000, 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) Parameter measurement of liquid crystal film An automatic birefringence meter KOBRA21ADH manufactured by Oji Scientific Instruments was used.
(5) DSC measurement (glass transition point (Tg) measurement)
After scraping off the liquid crystal layer, a differential scanning calorimeter (DSC, DSC-7 manufactured by Perkin Elmer) was used and the temperature was increased at a rate of 20 ° C./min.
(6) Measurement of viewing angle (isocontrast curve) The viewing angle of the liquid crystal display device was measured by EZcontrast 160R manufactured by ELDIM, and an isocontrast curve was obtained.

[Example 1]
A liquid crystal material solution was prepared as follows.
First, a liquid crystalline polymer of the following formula (11) was synthesized. The molecular weight in terms of polystyrene was a number average molecular weight Mn = 8000 and a weight average molecular weight Mw = 15000. In addition, although Formula (11) is described with the structure of the block polymer for convenience, the number represents the molar composition ratio of a monomer. After dissolving 1.0 g of the polymer of the formula (11) 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.

An alignment substrate was prepared as follows.
A 38 μm thick polyethylene naphthalate film (PEN film) (manufactured by Teijin DuPont Films Co., Ltd.) was cut into 15 cm square, and a 5% by mass solution of alkyl-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., MP-203 (PVA)). (A solvent is a mixed solvent of water and isopropyl alcohol having a 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.

(Preparation of laminate 1)
The liquid crystal material solution 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 irradiated with ultraviolet light of 600 mJ / cm ² (however, measured at 365 nm) with a high-pressure mercury lamp lamp, a liquid crystal material (homeotropic) The thickness of the alignment liquid crystal layer (0.8 μm) was cured to obtain a laminate 1 (homeotropic alignment liquid crystal layer / PVA layer / PEN film).

(Preparation of laminate 2)
In order to measure the optical parameters of the obtained liquid crystal layer (homeotropic alignment liquid crystal layer) and to protect the surface of the liquid crystal layer, a laminate 2 was prepared as follows.
The liquid crystal layer of the laminate 1 was transferred to a polyethylene terephthalate film (PET) via a commercially available UV curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.). That is, on the cured liquid crystal layer on the PVA layer, UV-3400 as an adhesive layer 1 is applied to a thickness of 5 μm, laminated with a polyethylene terephthalate (PET) film, and irradiated with ultraviolet rays from the PET film side. After the adhesive layer 1 was cured, the PVA layer and the PEN film were peeled off to obtain an intermediate laminate (PET film / adhesive layer 1 / homeotropic alignment liquid crystal layer) with a PET film.
On the homeotropic liquid crystal layer of the obtained intermediate laminate, a commercially available UV curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.) was applied as an adhesive layer 2 so as to have a thickness of 5 μm. After laminating with a cellulose (TAC) film and irradiating ultraviolet rays from the TAC film side to cure the adhesive layer 2, the PET film is peeled off, and the laminate 2 (adhesive layer 1 / homeotropic alignment liquid crystal layer) / Adhesive layer 2 / TAC film).

When the obtained laminate 2 is observed under a polarizing microscope in which the crossed Nicols are crossed, it has no disclination and has a uniform monodomain orientation, and it is a homeotropic orientation having a positive uniaxial refractive index structure from conoscopic observation. I understood. When this film was tilted and light was incident from an oblique direction and observed in the same manner with crossed Nicols, light transmission was observed. Moreover, the optical phase difference of the film was measured by an automatic birefringence measuring apparatus KOBRA21ADH. The measurement light was incident on the sample surface vertically or obliquely, and the homeotropic alignment was confirmed from the chart of the optical phase difference and the incident angle of the measurement light. In homeotropic alignment, the phase difference (front phase difference) in the direction perpendicular to the sample surface is almost zero. Regarding this sample, when the phase difference was measured obliquely in the slow axis direction of the liquid crystal layer, it was determined that the homeotropic alignment was obtained because the phase difference value increased as the incident angle of the measurement light increased. did it. From the above, it was judged that the homeotropic orientation was good.
In addition, Nx1 of the homeotropic alignment liquid crystal film was 1.54, Ny1 was 1.54, and Nz1 was 1.73.
Further, only the liquid crystal material portion of the laminated film was scraped, and Tg was measured using a differential calorimetry (DSC). The Tg was 100 ° C. Moreover, the pencil hardness of the liquid crystal layer surface of the film was about 2H, and a sufficiently strong film was obtained.

(Preparation of laminate 3)
Polyetherketone represented by the following formula (12) (manufactured by Nippon Shokubai Co., Ltd .: Δn = about 0.02) was dissolved in methyl isobutyl ketone to prepare 20 wt% varnish. This varnish was applied to a retardation film (Zeonor film, manufactured by Nippon Zeon Co., Ltd.) having an in-plane retardation of 140 nm and heat-treated at 100 ° C. for 10 minutes. As a result, a laminate 3 was obtained in which a polyetherketone film having a transparent and smooth surface, a thickness of 6 μm, and a negative optical anisotropy in the film thickness direction was formed on the ZEONOR film.

(Preparation of elliptically polarizing plate 1)
A retardation film having an in-plane retardation of 105 nm (Zeonor film, manufactured by Nippon Zeon Co., Ltd.) is subjected to corona discharge treatment (250 W · min / m ² ), and a linear polarizing plate (thickness: about 105 μm, Sumitomo Chemical) through an adhesive. SQW-062) manufactured by Co., Ltd. was attached to produce an elliptically polarizing plate 1 (linear polarizing plate / adhesive layer / Zeonor film).

(Preparation of elliptically polarizing plate 2)
The laminate 2 is subjected to corona discharge treatment (250 W · min / m ² ) on the adhesive layer 1 side, and is attached to the ZEONOR film side of the elliptically polarizing plate 1 via an adhesive, and the TAC film is peeled off. The elliptically polarizing plate 2 (linear polarizing plate / adhesive layer / zeonor film / adhesive layer / adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2) was obtained.

[Example 2]
(Preparation of elliptically polarizing plate 3)
The laminate 3 is subjected to a corona discharge treatment (250 W · min / m ² ) on the ZEONOR film side, and is adhered to the adhesive layer 2 side of the elliptical polarizing plate 2. / Pressure-sensitive adhesive layer / zeonor film / pressure-sensitive adhesive layer / adhesive layer 1 / homeotropic alignment liquid crystal layer / adhesive layer 2 / pressure-sensitive adhesive layer / zeonor film / polyetherketone film).

(Production of vertical alignment type liquid crystal display device)
As shown in FIG. 1, with respect to a commercially available VA type liquid crystal television arranged in the order of a backlight, a backlight side polarizing plate, a vertical alignment (VA) type liquid crystal cell, and a viewing side polarizing plate, Instead, the elliptically polarizing plate 3 of the present invention was disposed. FIG. 2 shows an isocontrast diagram. As compared with the case where the elliptically polarizing plate 3 is not used, it has been found that the viewing angle is enlarged and a good image can be obtained even when viewed obliquely. 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).

[Comparative Example 1]
(Preparation of elliptically polarizing plate 4)
The laminate 3 is subjected to a corona discharge treatment (250 W · min / m ² ) on the ZEONOR film side, and is adhered to the ZEONOR film side of the elliptically polarizing plate 1 through an adhesive, and the elliptically polarizing plate 4 (linearly polarizing plate 4). / Adhesive layer / zeonore film / adhesive layer / zeonore film / polyetherketone film).

  In contrast to the commercially available VA type liquid crystal television of the same type as that used for the manufacture of the vertical alignment type liquid crystal display device of Example 2, as shown in FIG. A polarizing plate 4 was disposed. FIG. 4 shows an isocontrast diagram. Compared with the case of using the elliptically polarizing plate 3 of the present invention, the effect of widening the viewing angle is small, and a good image cannot be obtained even when viewed obliquely.

[Example 3]
(Preparation of laminate 4)
A corona discharge treatment (250 W · min / m ² ) is applied to the adhesive layer 1 side of the laminate 2, and a retardation film having an in-plane retardation of 140 nm (Zeonor film, manufactured by Nippon Zeon Co., Ltd.) via an adhesive. Was stuck to obtain a laminate 4 (TAC film / adhesive layer 2 / homeotropic alignment liquid crystal layer / adhesive layer 1 / adhesive layer / zeonor film).

(Preparation of laminate 5)
After applying a corona discharge treatment (250 W · min / m ² ) to the ZEONOR film side of the laminate 4 and attaching a TAC film having negative uniaxiality (made by Fuji Film Co., Ltd.) via an adhesive. The TAC film adjacent to the adhesive layer 2 was peeled off to obtain a laminate 5 (adhesive layer 2 / homeotropic alignment liquid crystal layer / adhesive layer 1 / adhesive layer / zeonor film / adhesive layer / TAC film). .

(Preparation of elliptically polarizing plate 5)
The laminate 5 is subjected to a corona discharge treatment (250 W · min / m ² ) on the adhesive layer 2 side, and is adhered to the ZEONOR film side of the elliptically polarizing plate 1 via an adhesive. 5 (linear polarizing plate / adhesive layer / zeonor film / adhesive layer / adhesive layer 2 / homeotropic alignment liquid crystal layer / adhesive layer 1 / adhesive layer / zeonor film / adhesive layer / TAC film) was obtained. .

[Example 4]
(Preparation of laminated body 6)
A polyimide represented by the following formula (13) was dissolved in cyclohexanone to prepare a 15 wt% polyimide solution. This polyimide solution was applied to a retardation film having an in-plane retardation of 140 nm (Zeonor film, manufactured by Nippon Zeon Co., Ltd.) and heat-treated at 100 ° C. for 10 minutes. As a result, a laminate 6 was obtained on which a polyimide film having a transparent, smooth surface, a thickness of 6 μm, and a negative optical anisotropy in the direction perpendicular to the film surface was formed on the ZEONOR film.

(Preparation of laminate 7)
The laminate 6 is subjected to a corona discharge treatment (250 W · min / m ² ) on the ZEONOR film side, adhered to the adhesive layer 1 side of the laminate 2 via an adhesive, peeled off the TAC film, and the laminate 7. (Adhesive layer 2 / Homeotropic alignment liquid crystal layer / Adhesive layer 1 / Adhesive layer / Zeonor film / Polyimide film) was obtained.

(Preparation of elliptically polarizing plate 6)
The laminate 7 is subjected to a corona discharge treatment (250 W · min / m ² ) on the adhesive layer 2 side, and is attached to the ZEONOR film side of the elliptically polarizing plate 1 via an adhesive, whereby the elliptically polarizing plate of the present invention is used. 6 (linear polarizing plate / adhesive layer / zeonor film / adhesive layer / adhesive layer 2 / homeotropic alignment liquid crystal layer / adhesive layer 1 / adhesive layer / zeonor film / polyimide film) was obtained.

[Example 5]
(Preparation of laminated body 8)
The liquid crystal layer of the laminate 1 is subjected to a retardation film (Zeonor film, Nippon Zeon Co., Ltd.) having an in-plane retardation of 105 nm via a commercially available UV curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.). ). In other words, on the cured liquid crystal layer on the PVA layer, UV-3400 was applied as an adhesive layer 3 to a thickness of 5 μm, and pre-corona discharge treatment (250 W · min / m ² ) was applied. After laminating with a film and curing the adhesive layer 3 by irradiating ultraviolet rays from the ZEONOR film side, the PVA layer and the PEN film are peeled off, and an intermediate laminate (ZEONOR film / adhesive layer 3 / homeotropic alignment liquid crystal) Layer).
On the homeotropic liquid crystal layer of the obtained intermediate laminate, a commercially available UV curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.) was applied as an adhesive layer 4 to a thickness of 5 μm, and polyethylene terephthalate After laminating with (PET) film and irradiating ultraviolet rays from the PET film side to cure the adhesive layer 4, the PET film is peeled off, and the laminate 8 (Zeonor film / adhesive layer 3 / homeotropic orientation) A liquid crystal layer / adhesive layer 4) was obtained.

(Preparation of elliptically polarizing plate 7)
Corona discharge treatment (250 W · min / m ² ) is applied to the ZEONOR film side of the laminate 8, and a linear polarizing plate (thickness: about 105 μm, SQW-062 manufactured by Sumitomo Chemical Co., Ltd.) is attached via an adhesive. The elliptically polarizing plate 7 of the present invention (linear polarizing plate / adhesive layer / zeonore film / adhesive layer 3 / homeotropic alignment liquid crystal layer / adhesive layer 4) was prepared.

[Example 6]
(Preparation of elliptically polarizing plate 8)
The laminate 6 is subjected to a corona discharge treatment (250 W · min / m ² ) on the ZEONOR film side, and is adhered to the adhesive layer 4 side of the elliptically polarizing plate 7 via an adhesive, whereby the elliptically polarizing plate of the present invention is used. 8 (linear polarizing plate / adhesive layer / zeonor film / adhesive layer 3 / homeotropic alignment liquid crystal layer / adhesive layer 4 / adhesive layer / zeonor film / polyimide film) was obtained.

[Example 7]
(Preparation of film 1)
A retardation film (Pure Ace WR, manufactured by Teijin Limited) having a retardation in the plane was stretched uniaxially at 230 ° C. to obtain a film 1 having negative biaxiality. The in-plane retardation was 140 nm.

(Preparation of elliptically polarizing plate 9)
The elliptical polarizing plate 7 is subjected to a corona discharge treatment (250 W · min / m ² ) on the adhesive 4 side, and the film 1 is adhered via an adhesive, and the elliptical polarizing plate 9 of the present invention (linear polarizing plate / Adhesive layer / Zeonor film / Adhesive layer 3 / Homeotropic alignment liquid crystal layer / Adhesive layer 4 / Adhesive layer / Film 1) were obtained.

[Example 8]
(Preparation of film 2)
A retardation film having an in-plane retardation (Arton, manufactured by JSR Corporation) was longitudinally uniaxially stretched at 230 ° C. to obtain a film 2 having negative biaxiality. The in-plane retardation was 140 nm.

(Preparation of laminate 9)
Corona discharge treatment (250 W · min / m ² ) is applied to the adhesive layer 1 side of the laminate 2, the film 2 is attached via an adhesive, and the TAC film is peeled off to remove the laminate 9 (adhesive layer 2 / Homeotropic alignment liquid crystal layer / adhesive layer 1 / adhesive layer / film 2).

(Preparation of elliptically polarizing plate 10)
The laminate 9 is subjected to a corona discharge treatment (250 W · min / m ² ) on the adhesive layer 2 side, and is adhered to the ZEONOR film side of the elliptically polarizing plate 1 through an adhesive, whereby the elliptically polarizing plate of the present invention is used. 10 (linear polarizing plate / adhesive layer / zeonore film / adhesive layer 2 / homeotropic alignment liquid crystal layer / adhesive layer 1 / adhesive layer / film 2) was obtained.

(Production of vertical alignment type liquid crystal display device)
With respect to a commercially available VA type liquid crystal television arranged in the order of a backlight, a backlight side polarizing plate, a vertical alignment (VA) type liquid crystal cell, and a viewing side polarizing plate, as shown in FIG. Instead, the elliptically polarizing plate 10 of the present invention was disposed. FIG. 6 shows an isocontrast diagram. As compared with the case where the elliptically polarizing plate 10 is not used, the viewing angle is widened, and it was found that a good image can be obtained even when viewed obliquely.

[Comparative Example 2]
(Preparation of elliptically polarizing plate 11)
The film 2 was adhered to the ZEONOR film side of the elliptically polarizing plate 1 via an adhesive to obtain an elliptically polarizing plate 11 (linear polarizing plate / adhesive layer / ZEONOR film / adhesive layer / film 2). .

  In contrast to the commercially available VA type liquid crystal television of the same type as that used for the manufacture of the vertical alignment type liquid crystal display device of Example 8, as shown in FIG. A polarizing plate 11 was disposed. FIG. 8 shows an isocontrast diagram. Compared with the case of using the elliptically polarizing plate 10 of the present invention, the effect of widening the viewing angle was small, and a good image could not be obtained even when viewed obliquely.

[Reference Example 1]
A retardation film having an in-plane retardation of 140 nm (Zeonor film, manufactured by Nippon Zeon Co., Ltd.) is subjected to corona discharge treatment (250 W · min / m ² ), and a linear polarizing plate (thickness: about 105 μm, Sumitomo Chemical) through an adhesive. SQW-062) manufactured by Co., Ltd. was attached to produce an elliptically polarizing plate 12 (Zeonor film / adhesive layer / linear polarizing plate).

[Reference Example 2]
(Preparation of film 3)
First, a film 3 having negative uniaxial anisotropy in the film thickness direction was produced by the following method.
After saponifying the surface of the TAC film, an alignment film coating solution composed of 10 parts by weight of polyvinyl alcohol, 371 parts by weight of water, 119 parts by weight of methanol, and 0.5 parts by weight of glutaraldehyde was applied onto this film with a spin coater. . A film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film to obtain an alignment film.
Next, on the alignment film, 1.8 g of a discotic liquid crystalline compound represented by the following formula (14), 0.2 g of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), A solution obtained by dissolving 0.06 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy Co., Ltd.) and 0.02 g of a sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) in 3.9 g of methyl ethyl ketone was added to a spin coater. It was applied with. This was affixed to a metal frame and heated in a thermostatic bath at 125 ° C. for 3 minutes to align the discotic liquid crystal compound. Next, UV irradiation was performed for 30 seconds using a high pressure mercury lamp of 120 W / cm at 100 ° C. to crosslink the discotic liquid crystal compound. Then, it stood to cool to room temperature. Thus, a film 3 (discotic liquid crystal layer / alignment film / TAC film) was produced.

(Preparation of elliptically polarizing plate 13)
The elliptical polarizing plate 12 is subjected to a corona discharge treatment (250 W · min / m ² ) on the ZEONOR film side, and is attached to the TAC film side of the film 3 through an adhesive, and the elliptical polarizing plate 13 (discotic liquid crystal layer) / Alignment film / TAC film / adhesive layer / zeonore film / adhesive layer / linearly polarizing plate).

[Reference Example 3]
(Preparation of elliptically polarizing plate 14)
Corona discharge treatment (250 W · min / m ² ) is applied to the ZEONOR film side of the laminate 6, a linearly polarizing plate is attached via an adhesive, and an elliptically polarizing plate 14 (polyimide film / ZEONOR film / adhesive layer). / Linear polarizing plate).

[Reference Example 4]
(Preparation of film 4)
A film 4 having negative uniaxiality in the film thickness direction was produced by the following method.
A transparent polycarbonate film having a thickness of 110 μm (manufactured by Sumitomo Chemical Co., Ltd.) was stretched at a rate of 0.3 mm / sec while being heated to 170 ° C., and then heated to 170 ° C. and perpendicular to the initial stretching direction. Stretched in the direction at a speed of 0.5 mm / s. The polycarbonate film had a refractive index in the stretching direction increased by the second stretching, and the refractive index was about the same as the direction perpendicular to the stretching direction. For this reason, the polycarbonate film became a negative uniaxial optical anisotropic body including the extraordinary refractive index of the medium in the direction perpendicular to the stretching direction (that is, the direction perpendicular to the film surface).

(Preparation of elliptically polarizing plate 15)
A corona discharge treatment (250 W · min / m ² ) is applied to the ZEONOR film side of the elliptically polarizing plate 12, and the film 4 is attached via an adhesive, and an elliptically polarizing plate 15 (FILM 4 / adhesive layer / ZEONOR) Film / adhesive layer / linear polarizing plate).

[Reference Example 5]
(Preparation of film 5)
First, a film 5 having negative uniaxial anisotropy in the film thickness direction was produced by the following method.
90.5 parts by weight of a photopolymerizable mesogenic compound (LC242 manufactured by BASF), 9.5 parts by weight of a polymerizable chiral agent (LC756 manufactured by BASF) and a solvent (cyclohexanone) were adjusted and mixed so that the selective reflection center wavelength was 300 nm. A coating liquid (solid content 30 wt%) was prepared by adding 3 wt% of a photopolymerization initiator (Ciba Specialty Chemicals, Irgacure 907) to the solution. The coating solution was applied onto a stretched polyethylene terephthalate film (alignment substrate) using a spin coater so that the thickness after drying was 6 μm, and the solvent was dried at 100 ° C. for 2 minutes. The obtained film was irradiated with a first ultraviolet ray at 50 mW / cm ² for 1 second in an air atmosphere at 35 ° C. from the alignment substrate side. Then, it heated at 80 degreeC for 1 minute without the ultraviolet irradiation. Next, the second ultraviolet ray irradiation was performed at 5 mW / cm ² for 60 seconds in an air atmosphere at 80 ° C. Next, irradiation of the third ultraviolet ray from the alignment substrate side was performed at 80 mW / cm ² for 30 seconds in a nitrogen atmosphere at 50 ° C., and a broadband cholesteric liquid crystal layer having a selected wavelength of 250 to 350 nm was formed. Next, a triacetyl cellulose film was bonded to the cholesteric liquid crystal layer side with an acrylic pressure-sensitive adhesive, and dried at 80 ° C. for 5 minutes. Next, the alignment substrate was gently peeled off to obtain a film 5 (cholesteric liquid crystal layer / adhesive layer / TAC film).

(Preparation of elliptically polarizing plate 16)
The elliptical polarizing plate 12 is subjected to a corona discharge treatment (250 W · min / m ² ) on the ZEONOR film side, and is adhered to the TAC film side of the film 5 through an adhesive, and the elliptical polarizing plate 16 (cholesteric liquid crystal layer / Adhesive layer / TAC film / Adhesive layer / Zeonor film / Adhesive layer / Linear polarizing plate) were prepared.

[Reference Example 6]
(Preparation of elliptically polarizing plate 17)
Corona discharge treatment (250 W · min / m ² ) is applied to the ZEONOR film side of the laminate 3, and a linear polarizing plate is attached via an adhesive, and an elliptical polarizing plate 17 (polyetherketone film / ZEONOR film / adhesive). Agent layer / linear polarizing plate).

[Reference Example 7]
(Preparation of elliptically polarizing plate 18)
A linear polarizing plate was attached to the film 1 via an adhesive to obtain an elliptical polarizing plate 18 (film 1 / adhesive layer / linear polarizing plate).

[Reference Example 8]
(Preparation of elliptically polarizing plate 19)
A linear polarizing plate was attached to the film 2 via an adhesive to obtain an elliptical polarizing plate 19 (film 2 / adhesive layer / linear polarizing plate).

[Example 9]
(Production of vertical alignment type liquid crystal display device)
For a commercially available VA liquid crystal television arranged in the order of a backlight, a backlight side polarizing plate, a vertical alignment (VA) type liquid crystal cell, and a viewing side polarizing plate, as shown in FIG. Instead, the elliptically polarizing plate 6 of the present invention obtained in Example 4 was disposed, and the elliptically polarizing plate 17 obtained in Reference Example 6 was disposed in place of the backlight side polarizing plate. FIG. 10 shows an isocontrast diagram. As compared with the case where the elliptically polarizing plate 6 is not used, the viewing angle is widened, and it was found that a good image can be obtained even when viewed obliquely.

[Comparative Example 3]
(Preparation of elliptically polarizing plate 20)
The laminate 6 is subjected to a corona discharge treatment (250 W · min / m ² ) on the ZEONOR film side, and is attached to the ZEONOR film side of the elliptically polarizing plate 1 through an adhesive, and the elliptically polarizing plate 20 (linearly polarizing plate 20). / Adhesive layer / Zeonor film / Adhesive layer / Zeonor film / Polyimide film).
For the same type of commercially available VA type liquid crystal television as that used in the manufacture of the vertical alignment type liquid crystal display device of Example 9, as shown in FIG. 11, the elliptical polarizing plate 6 used in Example 9 was replaced with the elliptical polarizing plate. The polarizing plate 20 was disposed, and the elliptically polarizing plate 17 obtained in Reference Example 6 was disposed instead of the backlight side polarizing plate. FIG. 12 shows an isocontrast diagram. Compared with the case where the elliptically polarizing plate 6 of the present invention is used, the effect of widening the viewing angle is small, and a good image cannot be obtained even when viewed obliquely.

[Example 10]
An alignment substrate was prepared in the same manner as in Example 1 except that a 38 μm thick polyethylene terephthalate film (PET film) (manufactured by Toray Industries, Inc.) was used instead of the PEN film of Example 1.
The liquid crystal material solution obtained in Example 1 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 irradiated with ultraviolet light of 600 mJ / cm ² (however, measured at 365 nm) with a high-pressure mercury lamp, a liquid crystal material (homeotropic) The thickness of the alignment liquid crystal layer was 0.8 μm.
Since the PET film used as the substrate has a large birefringence and is not preferable as an optical film, the liquid crystal layer on the obtained alignment substrate is triacetylated via an ultraviolet curable adhesive in order to measure the parameters of the liquid crystal layer. Transferred to cellulose (TAC) film. That is, after the adhesive is applied to a thickness of 5 μm on the cured liquid crystal material layer on the PET film, laminated with the TAC film, and the adhesive is cured by irradiating ultraviolet rays from the TAC film side. The PET film was peeled off.

  When the obtained laminated film (PVA layer / liquid crystal layer / adhesive layer / TAC film) is observed under a polarizing microscope having a crossed Nicols, there is no disclination and the monodomain has a uniform orientation. It was found that the homeotropic alignment has a uniaxial refractive index structure. When this film was tilted and light was incident from an oblique direction and observed in the same manner with crossed Nicols, light transmission was observed. Moreover, the optical phase difference of the film was measured by an automatic birefringence measuring apparatus KOBRA21ADH. The measurement light was incident on the sample surface vertically or obliquely, and the homeotropic alignment was confirmed from the chart of the optical phase difference and the incident angle of the measurement light. In homeotropic alignment, the phase difference (front phase difference) in the direction perpendicular to the sample surface is almost zero. Regarding this sample, when the phase difference was measured obliquely in the slow axis direction of the liquid crystal layer, it was determined that the homeotropic alignment was obtained because the phase difference value increased as the incident angle of the measurement light increased. did it.

The obtained liquid crystal layer on the alignment substrate is a stretched polycarbonate retardation film having a retardation of 140 nm in the in-plane direction via an ultraviolet curable adhesive (Sumitomo Chemical Co., Ltd., thickness 40 μm, Nx2: 1). 5930, Ny2: 1.5887, Nz2: 1.5883). That is, an ultraviolet curable adhesive is applied onto the cured liquid crystal layer on the PET film, laminated with the above-mentioned stretched polycarbonate film, and adhered by irradiating with 400 mJ / cm ² ultraviolet light from the polycarbonate film side. After curing the agent, the PVA layer and the PET film were peeled off to obtain a laminated phase difference plate in which a homeotropic alignment liquid crystal layer and a polycarbonate stretched film were laminated.
The obtained laminated retardation plate (homeotropic alignment liquid crystal layer / adhesive layer / polycarbonate film) had an in-plane retardation of 140 nm and was biaxial.

(Preparation of elliptically polarizing plate 21)
A linearly polarizing plate (thickness: about 105 μm, SQW-062 manufactured by Sumitomo Chemical Co., Ltd.) is attached to the homeotropic alignment liquid crystal layer side of the thus obtained laminated retardation plate via an adhesive, and the present invention. The elliptically polarizing plate 21 (linear polarizing plate / adhesive layer / homeotropic alignment liquid crystal layer / adhesive layer / polycarbonate film) was prepared.
For a commercially available IPS liquid crystal television arranged in the order of a backlight, a backlight side polarizing plate, an IPS type liquid crystal cell, and a viewing side polarizing plate, as shown in FIG. The elliptically polarizing plate 21 was arranged. As a result, it was found that the viewing angle was widened compared to the case where the elliptically polarizing plate 21 was not used, and a good image was obtained even when viewed obliquely.

[Example 11]
Instead of the PEN film of Example 1, a stretched polycarbonate retardation film having a thickness of 40 μm and a retardation of 140 nm in the in-plane direction (manufactured by Sumitomo Chemical Co., Ltd., thickness 40 μm, Nx2: 1.5930, Ny2 : 1.5887, Nz2: 1.5883), and the alignment substrate was prepared in the same manner as in Example 1.

The liquid crystal material solution obtained in Example 1 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 irradiated with ultraviolet light of 600 mJ / cm ² (however, measured at 365 nm) with a high-pressure mercury lamp, a liquid crystal material (homeotropic) By curing the alignment liquid crystal layer having a thickness of 0.8 μm, a laminated phase difference plate in which a homeotropic alignment liquid crystal layer and a polycarbonate stretched film were laminated was obtained.
In order to confirm whether or not the obtained liquid crystal layer forms a good homeotropic alignment, the liquid crystal layer on the obtained liquid crystal layer / PVA layer / polycarbonate stretched film is subjected to TAC via an ultraviolet curable adhesive. Transferred to film. That is, on the liquid crystal layer cured on the PVA layer, an adhesive is applied to have a thickness of 5 μm, laminated with a TAC film, and irradiated with ultraviolet rays from the TAC film side to cure the adhesive, The stretched PVA / polycarbonate film was peeled off.

When the obtained laminated film (liquid crystal layer / adhesive layer / TAC film) is observed under a polarizing microscope with crossed Nicols, there is no disclination and the monodomain is uniformly oriented, and positive uniaxial refraction from conoscopic observation It was found that the homeotropic orientation has a refractive index structure. When this film was tilted and light was incident from an oblique direction and observed in the same manner with crossed Nicols, light transmission was observed. Moreover, the optical phase difference of the film was measured by an automatic birefringence measuring apparatus KOBRA21ADH. The measurement light was incident on the sample surface vertically or obliquely, and the homeotropic alignment was confirmed from the chart of the optical phase difference and the incident angle of the measurement light. In homeotropic alignment, the phase difference (front phase difference) in the direction perpendicular to the sample surface is almost zero. Regarding this sample, when the phase difference was measured obliquely in the slow axis direction of the liquid crystal layer, it was determined that the homeotropic alignment was obtained because the phase difference value increased as the incident angle of the measurement light increased. did it. From the above, it was judged that a good homeotropic alignment liquid crystal layer was formed.
The obtained laminated retardation plate (homeotropic alignment liquid crystal layer / PVA layer / polycarbonate film) had an in-plane retardation of 140 nm and was biaxial.

(Preparation of elliptically polarizing plate 22)
A linearly polarizing plate (thickness: about 105 μm, SQW-062 manufactured by Sumitomo Chemical Co., Ltd.) is attached to the homeotropic alignment liquid crystal layer side of the thus obtained laminated retardation plate via an adhesive, and the present invention. The elliptically polarizing plate 22 (linear polarizing plate / adhesive layer / homeotropic alignment liquid crystal layer / PVA layer / polycarbonate film) was prepared.
For a commercially available IPS liquid crystal television arranged in the order of a backlight, a backlight side polarizing plate, an IPS type liquid crystal cell, and a viewing side polarizing plate, as shown in FIG. The elliptically polarizing plate 22 was arranged. As a result, it was found that the viewing angle was widened compared to the case where the elliptically polarizing plate 22 was not used, and a good image was obtained even when viewed obliquely.

[Example 12]
Using a TAC film (thickness 80 μm) on which a cholesteric liquid crystal layer 5 μm exhibiting circular dichroism in a band of 400 to 700 nm is formed, the homeotropic alignment liquid crystal obtained in Example 10 is used on the liquid crystal layer. A retardation plate (thickness 50 μm) obtained by laminating a film and a polycarbonate stretched film retardation plate (front retardation 140 nm) is bonded via an adhesive layer (25 μm) formed of an acrylic adhesive. The brightness enhancement film of the invention (polycarbonate film / adhesive layer / homeotropic alignment liquid crystal layer / adhesive layer / cholesteric liquid crystal layer / TAC film) was produced.
Using the commercially available liquid crystal display in which the brightness enhancement film thus obtained is arranged in the order of the backlight, the backlight side polarizing plate, the liquid crystal cell, and the viewing side polarizing plate, as shown in FIG. It arrange | positioned between the light and the backlight side polarizing plate. As a result, it was found that a bright image having a luminance improvement rate of 30% was obtained as compared with the case where no luminance enhancement film was used.

6 is a schematic cross-sectional view of a vertical liquid crystal display device used in Example 2. FIG. Note that the pressure-sensitive adhesive or adhesive layer between the respective layers was not shown and omitted (the same applies to the following figures). It is a figure which shows contrast ratio when the vertical type liquid crystal display device in Example 2 is seen from all directions. 6 is a schematic cross-sectional view of a vertical liquid crystal display device used in Comparative Example 1. FIG. It is a figure which shows contrast ratio when the vertical liquid crystal display device in the comparative example 1 is seen from all directions. 10 is a schematic cross-sectional view of a vertical liquid crystal display device used in Example 8. FIG. It is a figure which shows contrast ratio when the vertical type liquid crystal display device in Example 8 is seen from all directions. 10 is a schematic cross-sectional view of a vertical liquid crystal display device used in Comparative Example 2. FIG. It is a figure which shows contrast ratio when the vertical liquid crystal display device in the comparative example 2 is seen from all directions. 10 is a schematic cross-sectional view of a vertical liquid crystal display device used in Example 9. FIG. It is a figure which shows contrast ratio when the vertical type liquid crystal display device in Example 9 is seen from all directions. 10 is a schematic cross-sectional view of a vertical liquid crystal display device used in Comparative Example 3. FIG. It is a figure which shows contrast ratio when the vertical liquid crystal display device in the comparative example 3 is seen from all directions. It is a conceptual diagram of the liquid crystal display used in Examples 10 and 11. 14 is a conceptual diagram of a liquid crystal display used in Example 12. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 View side polarizing plate 2 Zeonore film 3 Homeotropic alignment liquid crystal layer 4 Zeonore film 5 Polyetherketone film 6 Vertical alignment (VA) type liquid crystal cell 7 Arton film 8 Polyimide film 9 Backlight side polarizing plate 10 Backlight 11 Polycarbonate film 12 IPS type liquid crystal cell 13 Viewing side polarizing plate 14 Liquid crystal cell 15 Backlight side polarizing plate 16 1/4 wavelength plate 17 Homeotropic alignment liquid crystal film 18 Cholesteric liquid crystal film 19 TAC film 20 Brightness enhancement film 21 Diffuser plate 22 Condensing sheet 23 Collection Light sheet
24 Diffusion plate 25 Light guide plate 26 Reflection plate 27 Lamp 28 Backlight

Claims (8)

  An elliptically polarizing plate formed by laminating a homeotropic alignment liquid crystal layer in which homeotropic alignment is fixed, a retardation film having a retardation function, and a linear polarizing plate.   The homeotropic alignment liquid crystal layer is homeotropically aligned in a liquid crystal state with a liquid crystalline composition containing at least a side chain type liquid crystalline polymer compound having an oxetanyl group, and then reacted with the oxetanyl group. The elliptically polarizing plate according to claim 1, wherein the homeotropic alignment is fixed.   A liquid crystalline composition containing at least a side chain type liquid crystalline polymer compound having an oxetanyl group is aligned homeotropically in a liquid crystal state on an alignment substrate having homeotropic alignment ability, and then the oxetanyl group is reacted. At least the retardation film having a retardation function is adhered to the homeotropic alignment liquid crystal layer on the alignment substrate on which the homeotropic alignment is fixed using an adhesive or an adhesive means, and the homeotropic alignment liquid crystal layer is aligned with the alignment substrate. A method for producing an elliptically polarizing plate, wherein a homeotropic alignment liquid crystal layer and a retardation film having a retardation function are laminated and then laminated with a linear polarizing plate.   A liquid crystalline composition containing at least a side chain type liquid crystalline polymer compound having an oxetanyl group was homeotropically aligned in a liquid crystal state on a retardation film substrate having homeotropic alignment ability and retardation function. Thereafter, a laminate obtained by reacting the oxetanyl group to fix the homeotropic orientation and laminating a retardation film having a retardation function using an adhesive or an adhesive means, and then laminating a linear polarizing plate. A method for producing an elliptically polarizing plate.   An elliptically polarizing plate manufactured by the manufacturing method according to claim 3 or 4. The elliptically polarizing plate according to claim 1, 2 or 5, wherein the elliptically polarizing plate satisfies the following [1] to [4].
[1] 0 nm ≦ Re1 ≦ 50 nm
[2] −500 nm ≦ Rth1 ≦ −30 nm
[3] 30 nm ≦ Re2 ≦ 500 nm
[4] 0 nm ≦ Rth2 ≦ 300 nm
(Here, Re1 and Re2 represent in-plane retardation values of the homeotropic alignment liquid crystal layer and retardation film having retardation function, respectively, and Rth1 and Rth2 respectively represent homeotropic alignment liquid crystal layer and retardation function. The Re1, Re2, Rth1, and Rth2 are Re1 = (Nx1-Ny1) × d1 [nm] and Rth1 = (Nx1-Nz1) × d1, respectively. [Nm], Re2 = (Nx2−Ny2) × d2 [nm], Rth2 = (Nx2−Nz2) × d2 [nm], and d1 and d2 are a homeotropic alignment liquid crystal layer and a retardation function, respectively. The thickness of the retardation film Nx1, Ny1 is the main refractive index in the plane of the homeotropic alignment liquid crystal layer, Nx2, Ny, respectively. 2 is the in-plane main refractive index of the retardation film having the retardation function, and Nz1 and Nz2 are the main refractive indices in the thickness direction of the homeotropic alignment liquid crystal layer and the retardation film having the retardation function, respectively. Nz1> Nx1 ≧ Ny1, Nx2> Ny2.)   The in-plane retardation value (Re2) of the retardation film having a retardation function is in the range of 100 to 170 nm, and the elliptically polarizing plate according to claim 1, 2, or 5 is further laminated with at least one cholesteric liquid crystal film. A brightness enhancement film characterized by being made. An image display device to which the elliptically polarizing plate according to claim 1, 2, 5, or 6 or the brightness enhancement film according to claim 7 is applied.

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