JP2009151100A - Composite polarizing plate set and liquid crystal display device - Google Patents

Abstract

A set of composite polarizing plates capable of improving viewing angle characteristics in a liquid crystal display device and a liquid crystal display device using the same are provided.
A first polarizing plate, a first retardation plate, and a pressure-sensitive adhesive layer are laminated in this order, and the first retardation plate has an in-plane retardation value R _0. but 90 to 200 nm, N _z coefficient is 0.8 to 1.5, the first composite in which the absorption axis direction of the slow axis direction and a polarizing plate are arranged so as to intersect at an angle of 80 to 100 ° A polarizing plate, a second polarizing plate, a second retardation plate, and a pressure-sensitive adhesive layer have a structure laminated in this order. The second polarizing plate has a transparent protective film on one side of the polarizing film. The second retardation plate is laminated on the opposite side of the transparent protective film, and the second retardation plate contains an organically modified clay complex and a binder resin, and R ₀ is ₀ to 30 nm, and R _th is A composite polarizing plate set comprising a second composite polarizing plate in the range of 30 to 300 nm, and a liquid crystal display device using the same.
[Selection] Figure 1

Description

  The present invention relates to a composite polarizing plate set and a liquid crystal display device.

  In recent years, low-power consumption, low-voltage, light-weight and thin liquid crystal displays are rapidly spreading as information display devices such as mobile phones, portable information terminals, computer monitors, and televisions. With the development of liquid crystal technology, liquid crystal displays of various modes have been proposed, and problems with liquid crystal displays such as response speed, contrast, and narrow viewing angle are being solved. However, it is still pointed out that the viewing angle is narrower than that of a cathode ray tube (CRT), and various attempts have been made to expand the viewing angle.

  As one of such liquid crystal display devices, there is a vertical alignment (VA) mode liquid crystal display device in which rod-like liquid crystal molecules having positive or negative dielectric anisotropy are aligned perpendicular to a substrate. In this vertical alignment mode, in the non-driven state, since the liquid crystal molecules are aligned perpendicular to the substrate, the light passes through the liquid crystal layer without changing the polarization. For this reason, by arranging linearly polarizing plates on the top and bottom of the liquid crystal panel so that the absorption axes are orthogonal to each other, almost perfect black display can be obtained when viewed from the front, and a high contrast ratio can be obtained. it can.

  However, in the VA mode liquid crystal display device having only the polarizing plate in such a liquid crystal cell, the axial angle of the disposed polarizing plate is deviated from 90 ° when viewed obliquely. Light leakage occurs due to the birefringence of the rod-like liquid crystal molecules in the cell, and the contrast ratio is remarkably lowered, or the color at the time of squint varies greatly depending on the viewing angle. It is called “viewing angle characteristic” including the contrast ratio and color change at the time of strabismus.

  In order to eliminate this poor viewing angle characteristic, it is necessary to dispose an optical compensation film between the liquid crystal cell and the linear polarizing plate. Conventionally, a biaxial retardation plate is provided between the liquid crystal cell and the upper and lower polarizing plates. Specifications that each one is arranged, or specifications that a uniaxial retardation plate and a complete biaxial retardation plate are arranged one above and below the liquid crystal cell, or both on one side of the liquid crystal cell. Has been adopted. For example, in Japanese Patent Application Laid-Open No. 2001-109090 (Patent Document 1), in a vertical alignment mode liquid crystal display device, a plate (that is, a positive uniaxial retardation) is provided between upper and lower polarizing plates and a liquid crystal cell. Plate) and c-plate (ie, a complete biaxial retardation plate) are described.

A positive uniaxial retardation plate is a film having an _Nz coefficient of approximately 1.0, and a complete biaxial retardation plate is a film having an in-plane retardation value R _{0 of} approximately 0. is there. Here, a refractive index in the in-plane slow axis direction n _x of the film, the refractive index in the in-plane fast axis direction n _y of the film, the refractive index in the thickness direction of the film n _z, the thickness of the film d Then, the in-plane retardation value R ₀ , the thickness direction retardation value R _th , and the N _z coefficient are defined by the following equations (1) to (3), respectively.

_{R 0 = (n x -n y} ) × d (1)
R _th = [(n _x + _ny ) / 2−n _z ] × d (2)
N _z factor _{= (n x -n z) /} (n x -n y) (3)
In uniaxial film, since the _{n z ≒ (nearly equal) n} y, the N _z coefficient ≒ 1.0. Even in the case of a uniaxial film, the N _z coefficient may vary between about 0.8 and 1.5 due to variations in stretching conditions. The perfectly biaxial film, for the n _x ≒ n _y, the R ₀ ≒ 0. A complete biaxial film is a film having negative uniaxiality and having an optical axis in a normal direction because only the refractive index in the thickness direction is different (small), and as described above. , Sometimes called c-plate.

As the uniaxial retardation film, a resin film stretched by, for example, free end longitudinal uniaxial stretching or fixed end lateral uniaxial stretching is generally used. The free end uniaxially stretched film is obtained by, for example, longitudinally uniaxially stretching in the longitudinal direction (flow direction) of the film, and in that case, approximately 0.8 ≦ N _z coefficient ≦ 1. 2. A fixed-end lateral uniaxially stretched film is obtained by, for example, laterally uniaxially stretching with a tenter or the like, and often has a slight biaxiality of 1.1 ≦ N _z coefficient ≦ 1.5, but is generally uniaxial. In the present specification, the film including the film having the _Nz coefficient in the range is referred to as a uniaxial retardation film.

Although the viewing angle of the VA mode is considerably wide by using various retardation films including those disclosed in Patent Document 1, there is still room for improvement because it is still inferior to the CRT. It is said that.
JP 2001-109209 A (Claim 15 and paragraph 0036)

  The present invention has been made to solve the above-described problems, and an object of the present invention is to set a composite polarizing plate capable of improving viewing angle characteristics in a liquid crystal display device (particularly, a VA mode liquid crystal display device). And a liquid crystal display device using the same.

  As a result of intensive studies to further improve the viewing angle characteristics of the composite polarizing plate used in the VA mode liquid crystal display device, the present inventor has obtained a complete biaxial structure using a uniaxial retardation film and an organically modified clay composite. The color change from any angle can be achieved by forming the complete biaxial retardation film on a polarizing film without using a protective film having refractive index anisotropy. As a result, the present inventors have found that a liquid crystal display device having an excellent viewing angle characteristic can be obtained. That is, the present invention is as follows.

The present invention is a set of a first composite polarizing plate and a second composite polarizing plate used in a liquid crystal display device, and the first composite polarizing plate is a first polarizing plate, a first retardation plate, and a pressure-sensitive adhesive. The first phase difference plate has an in-plane retardation value R ₀ in the range of 90 to 200 nm, and N _z defined by the above formula (3). The coefficient is in the range of 0.8 to 1.5, and the slow axis direction and the absorption axis direction of the polarizing plate are arranged to intersect at an angle of 80 to 100 °, and the second composite polarizing plate is The second polarizing plate has a structure in which the second retardation plate and the pressure-sensitive adhesive layer are laminated in this order. The second polarizing plate has a transparent protective film laminated on one side of the polarizing film. The second retardation plate is laminated on the side opposite to the transparent protective film, and the second retardation plate is composed of an organically modified clay composite and a binder resin. Wherein the door, retardation value R ₀ in the plane is in the range of 0 to 30 nm, a thickness retardation value R _th is characterized in that in the range of 30 to 300 nm.

  In the set of the composite polarizing plate of the present invention, the polarizing film of the second polarizing plate and the second retardation plate are directly bonded, or between the polarizing film of the second polarizing plate and the second retardation plate. It is preferable that an optically isotropic primer layer is interposed.

The composite polarizing plate set of the present invention is preferably used for a VA mode liquid crystal display device.
The present invention is also a liquid crystal display device comprising the above-described composite polarizing plate set of the present invention and a liquid crystal cell, wherein the first composite polarizing plate is bonded to one side of the liquid crystal cell via the pressure-sensitive adhesive layer. In addition, the present invention also provides a liquid crystal display device in which a second composite polarizing plate is bonded to the other side of the liquid crystal cell via the pressure-sensitive adhesive layer.

  According to the present invention, it is possible to effectively suppress leakage of light passing through the liquid crystal cell obliquely by the first phase difference plate and the second phase difference plate. A certain liquid crystal display device (particularly, a VA mode liquid crystal display device) and a composite polarizing plate set therefor can be provided.

[1] Composite polarizing plate set In the composite polarizing plate set of the present invention, a first composite polarizing plate is disposed on one side of a liquid crystal cell, and a second composite polarizing plate is disposed on the other side to produce a liquid crystal display device. Therefore, it is provided as a combination of the first composite polarizing plate and the second composite polarizing plate. The first composite polarizing plate and the second composite polarizing plate in the present invention are respectively a polarizing plate (first polarizing plate or second polarizing plate), a retardation plate (first retardation plate or second retardation plate), and The pressure-sensitive adhesive layer has a structure laminated in this order.

[1-1] First Composite Polarizing Plate Here, FIG. 1 is a perspective view schematically showing a preferred example of the first composite polarizing plate 1 used in the composite polarizing plate set of the present invention, with each layer being separated. FIG. 2 is a perspective view schematically showing a first composite polarizing plate 11 of another preferred example used in the composite polarizing plate set of the present invention in a state where the respective layers are separated from each other. The first composite polarizing plates 1 and 11 shown in FIGS. 1 and 2 have the same structure except that the configurations of the first polarizing plates 2 and 12 are partially different. One phase difference plate 3 and a pressure sensitive adhesive layer 4 are laminated.

The first retardation plate 3 used for the first composite polarizing plates 1 and 11 in the present invention is characterized in that the in-plane retardation value R ₀ is in the range of 90 to 200 nm. If the in-plane retardation value R _{0 of} the first retardation plate is out of this range, the viewing angle characteristic of the liquid crystal display device on which the retardation value R ₀ is mounted deteriorates. The in-plane retardation value R ₀ of the first retardation plate in the present invention refers to a value measured using an automatic birefringence measuring device KOBRA-21ADH (manufactured by Oji Scientific Instruments). This automatic birefringence analyzer KOBRA-21ADH, as well as retardation value R ₀ in the plane, the thickness direction retardation value R _th, N _z coefficient is, the in-plane slow axis direction of the refractive index n _x, plane leading phase the refractive index of the axial n _y and refractive index n _z in the thickness direction, measured at the same time, so that the show.

The first retardation plate 3 used for the first composite polarizing plates 1 and 11 in the present invention has a uniaxiality in which the N _z coefficient defined by the above formula (3) is in the range of 0.8 to 1.5. This is a phase difference plate.

Since the first retardation plate used in the present invention aims to be uniaxial as described above, its N _z coefficient is set in the range of 0.8 to 1.5. It is difficult to N _z coefficient to produce a film of less than 0.8 by stretching. On the other hand, when the _Nz coefficient exceeds 1.5, the contrast viewing angle of the liquid crystal display device on which the Nz coefficient is mounted decreases. Incidentally, the first retardation plate in the plane of the film slow axis direction of the refractive index n _x, plane fast axis direction of the refractive index n _y and a thickness direction refractive index n _z in the present invention, further N _z coefficient As described above, it can be measured by, for example, an automatic birefringence measuring device KOBRA-21ADH (manufactured by Oji Scientific Instruments).

  The first retardation plate 3 having retardation characteristics as described above includes, for example, a resin made of a cellulose derivative, a cycloolefin resin typified by a norbornene resin, an olefin resin such as a propylene resin, and a polycarbonate resin. It can be suitably realized by using a stretched film in which a resin or the like is stretched and oriented.

  In addition, the first polarizing plate used for the first composite polarizing plate in the present invention can be one generally used in this field. For example, a dichroic dye (iodine, dichroism) is added to a polyvinyl alcohol-based resin. Generally, a structure in which a protective layer made of a resin film such as an acetyl cellulose resin, a cycloolefin resin, or an olefin resin is laminated on both sides or one side of a linear polarizing film on which an organic dye or the like is adsorbed and oriented is generally used. In FIG. 1, the case where the 1st polarizing plate 2 by which the protective layers 6 and 7 were provided on both surfaces of the linearly-polarized-light film 5 is shown, and also FIG. The case where the 1st polarizing plate 12 with which the protective layer 6 was provided in the surface on the opposite side to the side on which the 1st phase difference plate 3 was laminated | stacked is shown.

  The first composite polarizing plate in the present invention is a state in which the slow axis direction of the first retardation plate and the absorption axis direction of the first polarizing plate are arranged so as to intersect at an angle of 80 to 100 °. A retardation plate and a first polarizing plate are laminated. If the angle between the slow axis direction of the first retardation plate and the absorption axis direction of the first polarizing plate is out of this range, the liquid crystal display device on which it is mounted will leak light during black display and lower the contrast ratio. In addition, color unevenness is likely to occur. From the viewpoint of higher contrast ratio and color unevenness reduction, the angle formed by the slow axis direction of the first retardation plate and the absorption axis direction of the polarizing plate is preferably in the range of 85 to 95 °. More preferably, it is within the range of 89 to 91 °.

  The pressure-sensitive adhesive (adhesive) layer 4 formed on the side opposite to the side adjacent to the first polarizing plates 2 and 12 of the first retardation plate 3 in the first composite polarizing plates 1 and 11 has conventionally been a liquid crystal. It can be formed using various pressure-sensitive adhesives that have been used for display devices, for example, pressure-sensitive adhesives such as acrylic, rubber-based, urethane-based, silicone-based, and polyvinyl ether. A pressure-sensitive adhesive having a base polymer of an acrylic resin having excellent properties and heat resistance is suitable.

  The acrylic pressure-sensitive adhesive is not particularly limited, but (meth) acrylates such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate ) An acrylic ester base polymer and a copolymer base polymer using two or more of these (meth) acrylic esters are preferably used. Furthermore, polar monomers are copolymerized in these base polymers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, glycidyl (meth) ) A monomer having a functional group such as a carboxy group, a hydroxyl group, an amide group, an amino group, or an epoxy group, such as acrylate.

  These acrylic pressure-sensitive adhesives can of course be used alone, but usually a crosslinking agent is used in combination. Crosslinking agents include divalent or polyvalent metal salts that form carboxylic acid metal salts with carboxyl groups, polyamine compounds that form amide bonds with carboxyl groups Examples thereof include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are widely used as organic crosslinking agents.

  In the pressure-sensitive adhesive composition, in addition to the base polymer and the crosslinking agent described above, in order to adjust the adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. of the pressure-sensitive adhesive, if necessary, For example, blending appropriate additives such as natural and synthetic resins, tackifying resins, antioxidants, UV absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors, photopolymerization initiators, etc. You can also. Further, a pressure sensitive adhesive layer exhibiting light scattering properties can be formed by containing fine particles.

  The thickness of the pressure-sensitive adhesive layer is preferably 1 to 30 μm, and more preferably 5 to 25 μm. If the pressure-sensitive adhesive layer is too thin, the tackiness is lowered, and if it is too thick, problems such as the pressure-sensitive adhesive protruding are likely to occur.

  The method for forming the pressure-sensitive adhesive layer 4 on the first retardation plate 3 is not particularly limited, and the surface on which the pressure-sensitive adhesive layer of the first retardation plate 3 is to be formed is described above. It may be obtained by applying a solution containing each component including the base polymer and drying to form a pressure-sensitive adhesive layer, and then laminating a separate film that has been subjected to a release treatment such as a silicone type. Then, after forming the pressure-sensitive adhesive layer on the separate film, it may be transferred to the first retardation plate 3 and laminated. Further, when forming the pressure-sensitive adhesive layer on the first retardation plate, if necessary, at least one of the first retardation plate and the pressure-sensitive adhesive layer is subjected to an adhesion treatment such as a corona discharge treatment. Also good. The surface of the formed pressure-sensitive adhesive layer is usually protected by a separation film that has been subjected to a release treatment, and the separation film is applied to the liquid crystal cell by applying the composite polarizing plate set of the present invention to the liquid crystal cell as described later. It is peeled off before joining.

  In the first composite polarizing plate used in the present invention, for example, epoxy resin, urethane resin, cyano is used for bonding the polarizing film and the protective layer, or for bonding the polarizing film or protective layer and the first retardation plate. An adhesive containing an acrylate resin or an acrylamide resin as a component can be used. A preferable adhesive from the viewpoint of thinning the adhesive layer includes an aqueous adhesive, that is, an adhesive component dissolved in water or dispersed in water. Another preferred adhesive is a solventless adhesive, specifically, an adhesive layer that is formed by reaction-curing a monomer or oligomer by heating or irradiation with active energy rays.

  Examples of the adhesive component that can be a water-based adhesive include water-soluble crosslinkable epoxy resins and urethane resins. The water-soluble crosslinkable epoxy resin can be obtained, for example, by reacting epichlorohydrin with a polyamide polyamine obtained by a reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid. Mention may be made of polyamide epoxy resins. Specific examples of such polyamide epoxy resin commercial products include Sumire's Resin 650 (manufactured by Sumika Chemtex Co., Ltd.), Sumire's Resin 675 (manufactured by Sumika Chemtex Co., Ltd.), and the like.

  When a water-soluble epoxy resin is used as the adhesive component, it is preferable to mix other water-soluble resins such as a polyvinyl alcohol-based resin in order to further improve coatability and adhesiveness. Polyvinyl alcohol resins are modified such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol. Polyvinyl alcohol resin may be used. Among them, a saponified product of a copolymer of vinyl acetate and unsaturated carboxylic acid or a salt thereof, that is, carboxyl group-modified polyvinyl alcohol is preferably used. Here, the “carboxyl group” is a concept including —COOH and a salt thereof. Specific examples of commercially available products of carboxyl group-modified polyvinyl alcohol include Kuraray Poval KL-506 (manufactured by Kuraray Co., Ltd.), Kuraray Poval KL-318 (manufactured by Kuraray Co., Ltd.), Kuraray Poval KL-118 ((Co., Ltd.). ) Kuraray), Gohsenal T-330 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Gohsenal T-350 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), DR-0415 (manufactured by Denki Kagaku Kogyo Co., Ltd.), AF- 17 (manufactured by Nippon Vinegar-Poval), AT-17 (manufactured by Nippon Vinegar-Poval), AP-17 (manufactured by Nippon Vinegar-Poval)

  In the case of an adhesive containing a water-soluble epoxy resin, the epoxy resin and other water-soluble resins such as a polyvinyl alcohol-based resin added as necessary are dissolved in water to constitute an adhesive solution. In this case, the water-soluble epoxy resin preferably has a concentration in the range of 0.2 to 2 parts by weight per 100 parts by weight of water. Moreover, when mix | blending polyvinyl alcohol-type resin, the quantity is 1-10 weight part per 100 weight part of water, Furthermore, it is preferable to set it as 1-5 weight part.

  On the other hand, when a water-based adhesive containing a urethane resin is used, examples of suitable urethane resins include ionomer-type urethane resins, particularly polyester-type ionomer-type urethane resins. Here, the ionomer type is obtained by introducing a small amount of an ionic component (hydrophilic component) into the urethane resin constituting the skeleton. The polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer-type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion. Specific examples of commercially available polyester ionomer-type urethane resins include Hydran AP-20 (Dainippon Ink Chemical Co., Ltd.) and Hydran APX-101H (Dainippon Ink Chemical Co., Ltd.), both of which are emulsion forms. Etc.).

  When an ionomer type urethane resin is used as an adhesive component, it is usually preferable to add an isocyanate-based crosslinking agent. The isocyanate-based crosslinking agent is a compound having at least two isocyanato groups (—NCO) in the molecule. Examples thereof include 2,4-tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1, In addition to polyisocyanate monomers such as 6-hexamethylene diisocyanate and isophorone diisocyanate, adducts in which a plurality of these molecules are added to a polyhydric alcohol such as trimethylolpropane, and three molecules of diisocyanate are each of the isocyanate groups at one end. There are trifunctional isocyanurate forms in which isocyanurate rings are formed at the part, and polyisocyanate modified forms such as burettes formed by hydration and decarboxylation of the three diisocyanate molecules at the respective one-end isocyanato groups. . Specifically as a commercial item of an isocyanate type crosslinking agent, Hydran Assist C-1 (made by Dainippon Ink & Chemicals, Inc.) etc. are mentioned.

  When using an aqueous adhesive containing an ionomer type urethane resin, it is dispersed in water so that the concentration of the urethane resin is 10 to 70% by weight, and further 20 to 50% by weight, from the viewpoint of viscosity and adhesiveness. What was made is preferable. When the isocyanate crosslinking agent is blended, the blending amount may be appropriately selected so that the isocyanate crosslinking agent is 5 to 100 parts by weight with respect to 100 parts by weight of the urethane resin.

  The water-based adhesive as described above is applied to at least one of the protective layer, the first retardation plate, and the polarizing film, and two or three sheets to be bonded are bonded together to form the first polarizing plate or the composite polarizing plate. It can be. In the case where the protective layer 6 is laminated on one side of the polarizing film 5 and the first retardation plate 3 is laminated on the other side as illustrated in FIG. 2, the polarizing film 5 and the polarizing film 5 It is also possible to apply an adhesive between the first phase difference plate 3 and bond the three sheets simultaneously. The method of bonding the polarizing film and the protective layer is not particularly limited. For example, an adhesive is uniformly applied to the surface of the polyvinyl alcohol polarizing film or the protective layer, and the other film is laminated on the coated surface. For example, a method of laminating with a roll or the like and drying. Drying is performed at a temperature of about 60 to 100 ° C., for example. After drying, it is preferable to cure for about 1 to 10 days at a temperature slightly higher than room temperature, for example, about 30 to 50 ° C., from the viewpoint of further increasing the adhesive strength.

  When a solvent-free adhesive is used, it is preferably used that is cured by cationic polymerization by heating or irradiation with active energy rays from the viewpoint of reactivity. Here, the solventless adhesive refers to an adhesive that does not contain a significant amount of solvent, and generally includes a curable compound that is polymerized by heating or irradiation with active energy rays, and a polymerization initiator. Consists of including.

  In particular, from the viewpoint of weather resistance and refractive index, an epoxy compound that does not contain an aromatic ring in the molecule is suitably used as the curable compound. Examples of the adhesive using an epoxy compound that does not contain an aromatic ring in the molecule include those described in JP-A-2004-245925. Examples of such epoxy compounds that do not contain an aromatic ring include hydrides of aromatic epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. The curable epoxy compound used for the adhesive usually has two or more epoxy groups in the molecule.

  A hydride of an aromatic epoxy compound is obtained by selectively hydrogenating an aromatic epoxy compound to an aromatic ring under pressure in the presence of a catalyst. Examples of aromatic epoxy compounds include bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resins, cresol novolac epoxy resins, hydroxybenzaldehyde Examples include novolak-type epoxy resins such as phenol novolac epoxy resins; polyfunctional epoxy compounds such as glycidyl ether of tetrahydroxydiphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinylphenol. Among these hydrides of aromatic epoxy compounds, hydrogenated bisphenol A diglycidyl ether is preferred.

  Moreover, an alicyclic epoxy compound points out the compound which has at least one epoxy group couple | bonded with the alicyclic ring as shown in a following formula in a molecule | numerator (In formula, m represents the integer of 2-5).

A compound in which a group in which one or more hydrogen atoms in (CH ₂ ) _m in the above formula are removed is bonded to another chemical structure can be an alicyclic epoxy compound. Further, the hydrogen forming the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among them, it is preferable to use a compound having an epoxycyclopentane ring (m = 3 in the above formula) or an epoxycyclohexane ring (m = 4 in the above formula). Specific examples of the alicyclic epoxy compound include 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate , Ethylenebis (3,4-epoxycyclohexanecarboxylate), bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, diethylene glycol bis (3,4-epoxy Cyclohexyl methyl ether), ethylene glycol bis (3,4-epoxycyclohexyl methyl ether), 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro- [5.2.2.5. .2. 2] Henicosane (also known as 3,4-epoxycyclohexanespiro-2 ′, 6′-dioxanespiro-3 ″, 5 ″ -dioxanespiro-3 ′ ″, 4 ′ ″-epoxycyclohexane), 4- (3,4-epoxycyclohexyl) -2,6-dioxa-8,9-epoxyspiro [5.5] undecane, 4-vinylcyclohexene dioxide, bis-2,3-epoxycyclopentyl ether, dicyclopentadiene dioxide And so on.

  Moreover, as an aliphatic epoxy compound, polyglycidyl ether of an aliphatic polyhydric alcohol or its alkylene oxide adduct corresponds to this. Examples of such aliphatic epoxy compounds include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and polyethylene glycol. Obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as diglycidyl ether of propylene glycol, diglycidyl ether of propylene glycol, ethylene glycol, propylene glycol or glycerin. Examples thereof include polyglycidyl ethers of polyether polyols.

  The epoxy compounds illustrated here may be used alone or in combination with a plurality of epoxy compounds.

  The epoxy equivalent of the epoxy compound used for the solventless adhesive is usually 30 to 3000 g / equivalent, preferably 50 to 1500 g / equivalent. When the epoxy equivalent is less than 30 g / equivalent, the flexibility of the protective film after curing may be lowered, or the adhesive strength may be reduced. On the other hand, when it exceeds 3000 g / equivalent, compatibility with other components may be lowered.

  In order to cure the epoxy compound by cationic polymerization, a cationic polymerization initiator is blended. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation or heating of active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and starts an epoxy group polymerization reaction. From the viewpoint of workability, it is preferable that latency is imparted to any type of cationic polymerization initiator.

  In addition, when a cationic photopolymerization initiator is used, it is possible to cure at room temperature, reducing the need to consider the heat resistance of the polarizing film or distortion due to expansion, and the advantage that the protective film or the retardation plate can be bonded well There is. In addition, since the cationic photopolymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy compound. Examples of the compound that generates a cation species or a Lewis acid upon irradiation with active energy rays include aromatic diazonium salts, onium salts such as aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes. Among these, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.

  These photocationic polymerization initiators can be easily obtained as commercial products. Specifically, Kayrad PCI-220 (manufactured by Nippon Kayaku Co., Ltd.), Kayarad PCI-620 (manufactured by Nippon Kayaku Co., Ltd.), UVI -6990 (manufactured by Union Carbide), Adeka optomer SP-150 (manufactured by ADEKA), Adeka optomer SP-170 (manufactured by ADEKA), CI-5102 (manufactured by Nippon Soda Co., Ltd.), CIT -1370 (manufactured by Nippon Soda Co., Ltd.), CIT-1682 (manufactured by Nippon Soda Co., Ltd.), CIP-1866S (manufactured by Nippon Soda Co., Ltd.), CIP-2048S (manufactured by Nippon Soda Co., Ltd.), CIP-2064S (Nippon Soda Co., Ltd.), DPI-101 (Midori Chemical Co., Ltd.), DPI-102 (Midori Chemical Co., Ltd.), DPI-103 (Midori Chemical Co., Ltd.), DPI-1 5 (Midori Chemical Co., Ltd.), MPI-103 (Midori Chemical Co., Ltd.), MPI-105 (Midori Chemical Co., Ltd.), BBI-101 (Midori Chemical Co., Ltd.), BBI-102 ( Midori Kagaku), BBI-103 (Midori Kagaku), BBI-105 (Midori Kagaku), TPS-101 (Midori Kagaku), TPS-102 (Midori Kagaku) ), TPS-103 (manufactured by Midori Chemical Co., Ltd.), TPS-105 (manufactured by Midori Chemical Co., Ltd.), MDS-103 (manufactured by Midori Chemical Co., Ltd.), MDS-105 (manufactured by Midori Chemical Co., Ltd.) )), DTS-102 (manufactured by Midori Chemical Co., Ltd.), DTS-103 (manufactured by Midori Chemical Co., Ltd.), PI-2074 (manufactured by Rhodia), and the like. Among these, CI-5102 (manufactured by Nippon Soda Co., Ltd.) is one of preferred photocationic polymerization initiators. The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of epoxy compounds, Preferably it is 1-15 weight part.

  Furthermore, a photosensitizer can be used in combination as necessary. By using a photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. When mix | blending a photosensitizer, the compounding quantity is 0.1-20 weight part normally with respect to 100 weight part of epoxy compounds.

  The thermal cationic polymerization initiator is a compound that generates a cationic species or a Lewis acid by heating. Examples of such thermal cationic polymerization initiator include benzylsulfonium salt, thiophenium salt, thiolanium salt, benzylammonium, pyridinium salt, hydrazinium. Examples thereof include salts, carboxylic acid esters, sulfonic acid esters, and amine imides. Thermal cationic polymerization initiators can also be easily obtained as commercial products. For example, Adeka Opton CP77 (manufactured by ADEKA), Adeka Opton CP66 (manufactured by ADEKA), CI-2539 (manufactured by Nippon Soda Co., Ltd.) CI-2624 (manufactured by Nippon Soda Co., Ltd.), Sun Aid SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.), Sun Aid SI-80L (manufactured by Sanshin Chemical Industry Co., Ltd.), Sun Aid SI-100L (Sanshin) Chemical Industry Co., Ltd.).

  In the present invention, the above-described photocationic polymerization and thermal cationic polymerization may be used in combination.

  The epoxy adhesive may further contain a compound that promotes cationic polymerization, such as oxetanes and polyols.

  When a solventless type adhesive is used, the method for applying the adhesive to at least one of the polarizing film, the protective layer and the first retardation plate is not particularly limited. For example, a doctor blade, a wire bar, a die coat Various systems such as a coater, a comma coater, and a gravure coater can be used. Each of the above-described methods has an optimum viscosity range, and thus the viscosity may be adjusted using a small amount of solvent. As the solvent used for this purpose, for example, organic solvents such as hydrocarbons represented by toluene and esters represented by ethyl acetate can be used. The thickness of the adhesive layer using a solventless adhesive is usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less, and usually 1 μm or more.

  Solvent-free adhesives are coated with an active energy ray or heated as described above to cure the adhesive layer, thereby polarizing film and protective layer, polarizing film or protective layer and first layer. The retardation plate is fixed. In the case of curing by irradiation with active energy rays, ultraviolet rays are preferably used. Specific examples of the ultraviolet light source include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a black light lamp, and a metal halide lamp. The irradiation intensity and irradiation amount of active energy rays or ultraviolet rays are appropriately selected so as to sufficiently activate the polymerization initiator and not adversely affect the cured adhesive layer, polarizing film, protective layer, and retardation film. do it. Further, when cured by heating, it can be heated by a generally known method, and the temperature and time at that time sufficiently activate the polymerization initiator, and the cured adhesive layer or polarizing film The protective film may be appropriately selected so as not to adversely affect the protective film.

  As shown in FIG. 2, when the protective layer 6 is laminated on one surface of the polarizing film 5 and the first retardation plate is laminated on the other surface, the polarizing film 5 and the protective layer 6 are also polarized. For adhesion between the film 5 and the first retardation plate 3, the same kind of adhesive may be used, or different adhesives may be used for both, but the same adhesive is used for each. It is preferable because the number of steps and materials can be reduced.

  In addition, it is preferable to perform contact | adherence processes, such as a corona discharge process, in the side bonded with the polarizing film of a protective layer or a 1st phase difference plate. By performing the corona discharge treatment, the adhesive force between the polarizing film and the protective layer, the polarizing film or protective layer and the first retardation plate can be increased. The corona discharge treatment is a treatment for activating the resin film disposed between the electrodes by discharging by applying a high voltage between the electrodes. The effect of the corona discharge treatment varies depending on the type of electrode, electrode interval, voltage, humidity, type of resin film used, etc., for example, the electrode interval is set to 1 to 5 mm, and the moving speed is set to about 3 to 20 m / min. It is preferable to do this.

[1-2] Second Composite Polarizing Plate FIG. 3 is a perspective view schematically showing a preferred example of the second composite polarizing plate 21 used in the composite polarizing plate set of the present invention, with each layer being separated. is there. A second composite polarizing plate 21 shown in FIG. 3 is formed by laminating a second retardation plate 23 and a pressure-sensitive adhesive layer 24 in this order on a second polarizing plate 22. The second polarizing plate 22 has a structure in which a transparent protective film 26 is laminated on one surface of a polarizing film 25, and a second retardation plate 23 is laminated on the surface opposite to the transparent protective film 26.

FIG. 4 is a perspective view schematically showing a second composite polarizing plate 31 of another preferred example used in the composite polarizing plate set of the present invention in a state where the layers are separated from each other. The second composite polarizing plate 31 in the present invention is a primer layer that is optically isotropic between the polarizing film 25 of the second polarizing plate 22 and the second retardation plate 23 as in the example shown in FIG. 32 may be interposed. Here, optically isotropic means that the in-plane retardation value R ₀ is less than 10 nm and the thickness direction retardation value R _th is less than 20 nm.

  In the composite polarizing plate set of the present invention, the second polarizing plate constituting the second composite polarizing plate is composed of one having a structure in which a transparent protective film is laminated on one side of the polarizing film, and is opposite to the transparent protective film. A second retardation plate is laminated on the side. That is, it is important that no layer having refractive index anisotropy exists between the polarizing film constituting the second polarizing plate and the second retardation plate. When there is a layer having a retardation value in the thickness direction, such as a triacetyl cellulose film conventionally used as a protective layer of a polarizing plate, the viewing angle characteristics when it is applied to a liquid crystal display device The improvement effect is not sufficient. Specifically, as in the example shown in FIG. 3, the polarizing film 25 of the second polarizing plate 22 and the second retardation plate 23 may be directly joined, or as in the example shown in FIG. An optically isotropic primer layer 32 may be interposed between the polarizing film 25 of the second polarizing plate 22 and the second retardation plate 23. The polarizing film 25 and the second retardation plate 23 constituting the second polarizing plate 22 are directly bonded or bonded via an optically isotropic primer layer 32 to obtain a liquid crystal display device. There is an advantage that the color change at the time of squint becomes small and the viewing angle characteristic becomes good.

  The second polarizing plate used for the second composite polarizing plate in the present invention has a structure in which a transparent protective film is laminated on one side of a polarizing film, and a second retardation plate is laminated on the opposite side of the transparent protective film. As long as the condition of being satisfied, the first polarizing plate used for the first composite polarizing plate can be the one generally used in this field. For example, a resin film such as an acetyl cellulose resin, a cycloolefin resin, or an olefin resin is applied to one side of a linear polarizing film in which a dichroic dye (iodine, dichroic organic dye, etc.) is adsorbed and oriented on a polyvinyl alcohol resin. A structure in which a protective layer is laminated is generally used. FIG. 3 shows a case where the second polarizing plate 22 having a protective layer 26 provided on one side of the linearly polarizing film 25 is used.

The second retardation plate 23 used in the present invention has an in-plane retardation value R _{0 in} the range of ₀ to 30 nm (preferably 0 to 10 nm), and a thickness direction retardation value R _th of 30 to 300 nm ( Preferably, it is in the range of 50 to 300 nm). When the in-plane retardation value R _{0 of} the second retardation plate 23 exceeds 30 nm, depolarization associated with the front phase difference occurs, and the contrast ratio decreases. On the other hand, when the thickness direction retardation value R _{th of} the second retardation plate 23 is less than 30 nm, the birefringence of the liquid crystal of the liquid crystal cell cannot be sufficiently canceled, and the viewing angle becomes narrow, and 300 nm. On the contrary, the birefringence of the liquid crystal in the liquid crystal cell is overcompensated, and the viewing angle is narrowed. Note that the in-plane retardation value R ₀ and the thickness direction retardation value R _th of the second retardation plate 23 are automatically duplicated in the same manner as the in-plane retardation value R _{0 of} the first retardation plate described above. It refers to a value measured using a refraction measuring device KOBRA-21ADH (manufactured by Oji Scientific Instruments). Such retardation characteristics can be realized by forming the second retardation plate 23 using an organically modified clay composite and a binder resin.

  Here, the organically modified clay composite is a composite of an organic compound and a clay mineral having a layered structure, and can be dispersed in an organic solvent. The second retardation plate 23 according to the present invention prepares a coating solution containing such an organically modified clay complex together with a binder resin in an organic solvent, and removes the solvent after coating the coating solution in layers. It is formed by doing.

  Examples of the clay mineral having a layered structure include a smectite group and a swellable mica. Among them, the smectite group is preferably used because of its excellent transparency. Examples of those belonging to the smectite group include hectorite, montmorillonite, and bentonite. Among these, those chemically synthesized are preferable in that they have few impurities and are excellent in transparency. In particular, synthetic hectorite having a controlled particle size is preferably used because scattering of visible light is suppressed.

Examples of organic compounds that are complexed with clay minerals include compounds that can react with or interact with oxygen atoms and hydroxyl groups of clay minerals, or ionic compounds that can be exchanged with exchangeable cations. There is no particular limitation as long as the organic modified clay complex can be swollen or dispersed in an organic solvent. Specific examples of compounds that can interact with oxygen atoms and hydroxyl groups of clay minerals include surface modifiers such as silane coupling agents and titanium coupling agents, and ε- which can be modified by polymerization in the system. Examples include caprolactam, polyvinyl pyrrolidone, and alkyl-substituted pyrrolidone. Specific examples of ionic compounds that can be exchanged for exchangeable cations include nitrogen-containing compounds and phosphorus-containing compounds. Examples include primary, secondary or tertiary amines, quaternary ammonium compounds, 4 Grade phosphonium compounds. Among them, quaternary ammonium compounds and quaternary phosphonium compounds are preferably used because of easy cation exchange, and examples thereof include those having a long-chain alkyl group and those having an alkyl ether chain. In particular, those having a long-chain alkyl group having 6 to 30 carbon atoms, particularly 6 to 10 carbon atoms, and — (CH ₂ CH (CH ₃ ) O) _n H having n = 1 to 50, particularly n = 5 to 30. Or a group having a — (CH ₂ CH ₂ CH ₂ O) _n H group is preferred.

  In many cases, organically modified clay composites contain chlorine-containing compounds as impurities due to various auxiliary materials used in the production thereof. When the amount of such a chlorinated compound is large, there is a possibility that bleed out from the film occurs when the second retardation plate 23 is formed. In that case, when the 2nd phase difference plate 23 is bonded to liquid crystal cell glass via a pressure sensitive adhesive, adhesive force will fall significantly over time. Therefore, it is preferable to remove the chlorine compound from the organically modified clay complex by washing, and if it is contained in an organic solvent in a state where the amount of chlorine contained therein is 2000 ppm or less, such adhesive strength Can be suppressed. The removal of the chlorine compound can be performed by a method of washing the organically modified clay complex with water.

  Two or more organic modified clay composites can be used in combination. Examples of suitable organically modified clay composites include Lucentite STN (Corp Chemical Co., Ltd.) and Lucentite SPN (Corp Chemical Co., Ltd.), which are composites of synthetic hectorite and quaternary ammonium compounds. Etc.

  Such an organically modified clay complex dispersible in an organic solvent is used in combination with a binder resin from the viewpoints of ease of coating on a substrate and the like, development of optical properties, mechanical properties, and the like. The binder resin used in combination with the organically modified clay complex is preferably one that dissolves in an organic solvent such as toluene, xylene, acetone, or ethyl acetate, especially one having a glass transition temperature of room temperature or lower (about 20 ° C. or lower). It is done. In addition, in order to obtain good wet heat resistance and handling properties required when applied to a liquid crystal display device, those having hydrophobic properties are desirable. Examples of such preferable binder resins include polyvinyl acetal resins such as polyvinyl butyral and polyvinyl formal, cellulose resins such as cellulose acetate butyrate, acrylic resins such as butyl acrylate, urethane resins, methacrylic resins, epoxy resins, and polyesters. Resin etc. are mentioned. Of these, urethane resin is preferred because the dispersibility of the organoclay composite is good.

  Specific examples of commercially available binder resins include Denkabutyral # 3000-K (manufactured by Denki Kagaku Kogyo Co., Ltd.), an aldehyde-modified resin of polyvinyl alcohol, and Aron S1601 (Toagosei Co., Ltd.), an acrylic resin. And SBU lacquer 0866 (Sumika Bayer Urethane Co., Ltd.), which is an isophorone diisocyanate-based urethane resin.

  The content ratio of the organically modified clay complex and the binder resin in the second phase difference plate 23 is in the range of 1: 2 to 10: 1, particularly in the range of 1: 1 to 2: 1, in the former: latter weight ratio. It is preferable from the viewpoint of improving mechanical characteristics such as prevention of cracking of the second retardation plate 23.

  As described above, the organically modified clay complex and the binder resin are applied onto the substrate in the state of a coating liquid prepared by being contained in an organic solvent. In this case, generally, the binder resin is dissolved in an organic solvent, and the organic modified clay complex is dispersed in the organic solvent. The solid content concentration of this coating solution is not limited unless the coating solution after preparation is gelled or clouded within a practically acceptable range, but usually the total solid content of the organically modified clay complex and the binder resin. The partial concentration is used in a range of about 3 to 15% by weight. The optimal solid content concentration varies depending on the types of the organic modified clay complex and the binder resin and the composition ratio of the both, and is thus set for each composition. Moreover, you may add various additives, such as a viscosity modifier for improving the applicability | paintability at the time of film forming, and the hardening | curing agent for improving hydrophobicity and / or durability further.

  The coating liquid preferably has a moisture content measured by a Karl Fischer moisture meter within a range of 0.15 to 0.35% by weight. When the water content exceeds 0.35% by weight, phase separation occurs in a water-insoluble organic solvent, and the coating liquid tends to separate into two layers. On the other hand, when the moisture content is less than 0.15% by weight, the haze value of the formed second retardation plate may be increased.

  The method for setting the water content of the coating liquid within the above-mentioned range is not particularly limited, but the water content can be easily adjusted by adding water to the coating liquid. The water content of 0.15% by weight or more is hardly exhibited by simply mixing the organic solvent, the organically modified clay complex and the binder resin as described above by a usual method. Therefore, it is preferable to adjust the water content within the above range by adding a small amount of water to the coating liquid in which the organic solvent, the organically modified clay complex and the binder resin are mixed. The time point at which water is added is not particularly limited, but if a predetermined amount of water is added after preparing a coating liquid and measuring the moisture content after sampling for a certain period of time, reproducibility and accuracy will be improved. The water content can be controlled, which is preferable.

  The method for applying the coating liquid is not particularly limited, and various known methods such as a direct gravure method, a reverse gravure method, a die coating method, a comma coating method, and a bar coating method can be used.

  The said coating liquid is apply | coated directly or via a primer layer on the polarizing film which comprises a 2nd polarizing plate, and a solvent is removed by drying, and it becomes a 2nd phase difference plate.

  The pressure-sensitive adhesive layer 24 formed on the side opposite to the side adjacent to the second polarizing plate 22 of the second retardation plate 23 in the second composite polarizing plate 21 in the present invention is the first composite polarizing plate 1, 11. In the same manner as described above with respect to the pressure-sensitive adhesive layer 4, it can be formed using various pressure-sensitive adhesives conventionally used for liquid crystal display devices. In the second composite polarizing plate, the adhesion between the protective layer and the polarizing film is the adhesion between the protective layer and the polarizing film, the protective layer or the polarizing film and the first retardation plate in the first composite polarizing plate. The above-mentioned adhesives that are preferably used in the above are similarly used.

  Next, the form which forms the 2nd phase difference plate 23 through the primer layer 32 in one surface of the polarizing film 25 as shown in FIG. 4 is demonstrated. The primer layer 32 is made of a transparent resin formed by coating. The primer generally means an undercoat, but the primer layer in the present invention functions as an undercoat layer of a second retardation plate formed by coating. Moreover, even if it is a case where the coating liquid for 2nd phase difference plates is apply | coated directly there by presence of the primer layer 32, the influence on the polarizing film by the organic solvent in the coating liquid can be prevented. it can. Further, it can also serve as an adhesive layer between the second retardation plate 23 and the linearly polarizing film 25 formed by coating.

  The material of the primer layer 32 is not particularly limited, and a resin dispersible in an organic solvent such as a polyolefin resin, a polyurethane resin, or a polyacrylate resin may be used, but from the viewpoint of adhesion with a polarizing film, A water-soluble resin is preferably used. Examples of such water-soluble resins include polyvinyl alcohol resins and water-soluble acrylic resins. Among these, a polyvinyl alcohol-based resin is preferably used because it is particularly excellent in adhesiveness with a polarizing film usually composed of a polyvinyl alcohol-based resin. Polyvinyl alcohol resins include partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, polyvinyl alcohol modified with anions such as carboxyl groups, acetoacetyl group modified polyvinyl alcohol, methylol group modified polyvinyl alcohol, amino group modified polyvinyl alcohol. Such a modified polyvinyl alcohol resin may be used. Examples of suitable commercially available polyvinyl alcohol resins include partially saponified polyvinyl alcohol PVA-403 (manufactured by Kuraray Co., Ltd.) and anion-modified polyvinyl alcohol KL-506 (manufactured by Kuraray Co., Ltd.). (The details of these Kuraray polyvinyl alcohols are listed as “KURARAY POVAL” on the company's POVAL resin website <URL: http://www.poval.jp/japan/poval/topics/index.html> (Access date: December 3, 2007)).

  A water-soluble resin such as a polyvinyl alcohol resin is poor in water resistance by itself because of its water-solubility, and therefore needs to be cross-linked using some curing agent in order to improve water resistance. For crosslinking, a method of applying a primer layer coating solution containing a curing agent capable of crosslinking a water-soluble resin can be employed. In this case, the reaction between the water-soluble resin and the curing agent proceeds mainly by removing the solvent. The higher the reactivity of the curing agent with the water-soluble resin, the higher the crosslinking density after the reaction, so that the resulting primer layer exhibits good water resistance.

  Examples of the curing agent include a polyamide epoxy resin, a water-dispersible isocyanate crosslinking agent, a water-soluble organic titanium compound, and a water-soluble organic zirconium compound. Among these, water-soluble organic titanium compounds and water-soluble organic zirconium compounds having good water resistance are particularly preferably used. The water-soluble organic titanium or organic zirconium compound here has a structure in which an organic group is directly bonded to titanium or zirconium, or an organic group is bonded through an oxygen atom or a nitrogen atom, A compound having at least one in the molecule and thereby exhibiting water solubility. The organic group means a group containing at least a carbon atom, and examples thereof include an alkyl group, an alkoxy group, an acyl group, and an amino group. Further, the bond does not mean only a covalent bond, but may be a coordinate bond by coordination of a chelate compound or the like. As described above, the solvent of the primer layer coating solution is preferably water alone or a mixture of water with a small amount of organic solvent. From this viewpoint, organic titanium compounds and organic zirconium compounds are also used. Use water-soluble one.

  Typical examples of such water-soluble organic titanium compounds and organic zirconium compounds include structures represented by the following formulas (1) to (4).

Formula (1): (HO) ₂ Ti [OCH (CH ₃ ) COOH]
Formula (2): (C ₃ H ₇ O) ₂ Ti [OCH ₂ CH ₂ N (CH ₂ CH ₂ OH) ₂ ] ₂
Formula (3): (HO) ₂ Zr [OCH (CH ₃ ) COOH] ₂
Formula (4): (C ₃ H ₇ O) ₂ Zr [OCH ₂ CH ₂ N (CH ₂ CH ₂ OH) ₂ ] ₂
As a commercially available water-soluble organic titanium compound, specifically, ORGATICS TC-310 (Matsumoto Pharmaceutical Co., Ltd., a chemical abbreviation “titanium lactate” designated by the manufacturer; the chemical structure is the above formula (1); Component 44% by weight, isopropyl alcohol 40% by weight, water 16% by weight solution), ORGATICS TC-315 (Matsumoto Pharmaceutical Co., Ltd., manufacturer name chemical abbreviation “titanium lactate”; ); 44% by weight of active ingredient, 56% by weight of water solution), ORGATICS TC-300 (Matsumoto Pharmaceutical Co., Ltd., manufacturer name chemical abbreviation “titanium lactate”; chemical structure is the above formula (1); Component 42% by weight, isopropyl alcohol 38% by weight, water 20% by weight solution), ORGATICS TC-400 (Matsumoto Pharmaceutical Co., Ltd., manufacturer abbreviation chemical name “titanium triethanol” “Aminate”; chemical structure is the above formula (2); 80% by weight of active ingredient, 20% by weight of isopropyl alcohol solution), ORGATIZ ZB-400 (Matsumoto Pharmaceutical Co., Ltd. The chemical structure is confidential to the manufacturer, so it is unknown except that it is a water-soluble organic zirconium compound; a solution containing 30% by weight of active ingredients and 70% by weight of water).

  The ratio of the water-soluble resin and the organometallic compound used to form the primer layer 32 is from 0.1 to 200 parts by weight of the organometallic compound with respect to 100 parts by weight of the water-soluble resin. What is necessary is just to determine suitably according to the kind etc. of a metal compound, and selecting from the range of 0.1-100 weight part especially is preferable. The organometallic compound is effective in improving the water resistance of the primer layer even in a relatively small amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the water-soluble resin, but is incorporated in a large amount as 5 to 100 parts by weight. As a result, the water resistance may be further improved.

  Such a primer layer coating liquid preferably uses water as a solvent and has a solid content concentration of about 1 to 25% by weight. Moreover, alcohol etc. can also be added as needed in order to improve the wettability to a base material. Although the alcohol to add is not specifically limited, Methanol, ethanol, isopropanol, n-propanol, n-butanol, etc. are illustrated. Further, the thickness of the primer layer 32 is preferably 10 μm or less, particularly 2 μm or less, more preferably 1 μm or less from the viewpoint of water resistance.

  On the primer layer 32 thus formed, a second retardation plate-forming coating solution can be applied and dried to form a second retardation plate in accordance with the method described above.

[2] Liquid Crystal Display Device FIG. 5 (a) is a cross-sectional view schematically showing an example of a liquid crystal display device manufactured using the set of composite polarizing plates of the present invention, and FIG. 5 (b) shows each layer. It is a top view shown in the state shifted mutually. 5 shows a set of composite polarizing plates in which the first composite polarizing plate 1 of the example shown in FIG. 1 and the second composite polarizing plate 21 of the example shown in FIG. 3 are combined. 1 is affixed to one side of the liquid crystal cell 50 and the second composite polarizing plate 21 is affixed to the other side of the liquid crystal cell 50, schematically showing the respective layers separated (pressure-sensitive adhesive layer). Is not shown in the figure).

  The set of the composite polarizing plate of the present invention is suitably used for a vertical alignment (VA) mode liquid crystal display device. When used in a liquid crystal display device in a vertical alignment mode, as shown in FIG. 5B, the first composite polarizing plate 1 has an absorption axis direction 2a of the first polarizing plate 2 on the viewing side (front side) of the liquid crystal cell. Are arranged so as to be parallel to the horizontal direction (longitudinal direction) of the liquid crystal cell, and the absorption axis direction 2a of the first polarizing plate 2 and the slow axis direction 3a of the first retardation plate 3 intersect each other substantially perpendicularly. Placed and pasted. In the second composite polarizing plate 21, the absorption axis direction 22a of the second polarizing plate 22 is parallel to the vertical direction (short direction) of the liquid crystal cell on the side opposite to the viewing side (rear side) of the liquid crystal cell. Furthermore, the second polarizing plate 22 is disposed and pasted so that the absorption axis direction 22a of the second polarizing plate 22 intersects the absorption axis direction 2a of the first polarizing plate 2 in the first composite polarizing plate 1 substantially perpendicularly. In this case, the type of the liquid crystal cell is not particularly limited as long as it is a VA mode liquid crystal cell.

  In this invention, it is a liquid crystal display device provided with the set of the composite polarizing plates of this invention as mentioned above, and a liquid crystal cell, Comprising: While arrange | positioning a 1st composite polarizing plate in the one side of a liquid crystal cell, the other side of a liquid crystal cell The present invention also provides a liquid crystal display device in which a second composite polarizing plate is disposed. In this liquid crystal display device, the pressure-sensitive adhesive layer constituting the first polarizing plate is bonded to the liquid crystal cell, and the pressure-sensitive adhesive layer constituting the second polarizing plate is bonded to the liquid crystal cell. Is done. As described above, the set of the composite polarizing plate of the present invention hardly changes the color even when the viewing angle is changed, and can obtain a favorable viewing angle characteristic. Therefore, the liquid crystal display device of the present invention is particularly preferably realized as a VA mode liquid crystal display device.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. The in-plane retardation value R ₀ , thickness direction retardation value R _th and N _z coefficient are all values measured using an automatic birefringence measuring apparatus KOBRA-21ADH (manufactured by Oji Scientific Instruments). It is.

<Example 1>
(Preparation of the first composite polarizing plate)
A polarizing plate (first polarizing plate) having triacetyl cellulose as a protective layer on one surface of a polarizing film in which iodine is adsorbed and oriented on polyvinyl alcohol was prepared. On the other hand, a film made of cycloolefin (norbornene) resin (Zeonor film, manufactured by Optes Co., Ltd.) was stretched laterally uniaxially to obtain a first retardation plate that is a uniaxial retardation film. The in-plane retardation value R ₀ of this first retardation plate was 140 nm, and the N _z coefficient was 1.40. The first polarizing plate is disposed on one surface of the first retardation plate, the side where the polarizing film is exposed is adjacent to the first retardation plate, and the absorption axis direction of the first polarizing plate and the first retardation The plates were bonded together with an adhesive in a state where they were arranged so as to be orthogonal to the slow axis direction of the plate. Furthermore, the pressure-sensitive adhesive layer (P-3132, manufactured by Lintec Corporation) formed on the separate film is transferred to the surface opposite to the side where the first polarizing plate of the first retardation plate is adjacent. A first composite polarizing plate was produced.

(Production of second composite polarizing plate)
As the organically modified clay complex, Lucentite STN (produced by Corp Chemical Co., Ltd.), which is a complex of synthetic hectorite and trioctylmethylammonium ion, is used, and the solid content of isophorone diisocyanate-based polyurethane resin is used as the binder resin. Using SBU lacquer 0866 (manufactured by Sumika Bayer Urethane Co., Ltd.), which is a resin varnish with a concentration of 30%, a coating solution for preparing a second retardation plate was prepared with the following composition.

-Urethane resin varnish (SBU lacquer 0866) 16.0 parts-Organic modified clay complex (Lucentite STN) 7.2 parts-Toluene 76.8 parts-Water 0.3 part The organic modified clay complex used here is The product was obtained by the manufacturer after washing with acid after producing synthetic hectorite before organic modification, organically modifying it, and further washing with water. The amount of chlorine contained therein was 1111 ppm. This coating solution was prepared by mixing with the above composition, stirring, and filtering with a filter having a pore size of 1 μm, and the water content measured with a Karl Fischer moisture meter was 0.25%. The solid content weight ratio of the organic modified clay complex / binder resin in this coating solution is 6/4 (7.2 / 4.8).

  The coating liquid prepared as described above is dried on the polarizing film side surface of the polarizing plate (second polarizing plate) having triacetyl cellulose as a protective layer on the same side as that used for the production of the first composite polarizing plate. The coating retardation layer (second retardation plate) was formed by direct coating with a desktop gap coater so that the subsequent thickness was 9.5 μm and drying at 80 ° C. for 2 minutes. Further, the pressure-sensitive adhesive layer (P-3132, manufactured by Lintec Corporation) formed on the separate film is transferred to the surface of the coating retardation layer (second retardation plate), and the second composite polarizing plate is transferred. Produced.

Separately, a coating retardation layer having a thickness of 9.5 μm (substantially the same as the above-mentioned second retardation plate) is formed on a glass substrate in the same manner as described above. As a result, the in-plane retardation value R ₀ was 0.1 nm, and the retardation value R _{th in the} thickness direction was 151 nm.

(Liquid crystal display device)
After disassembling a commercially available liquid crystal television (BRAVIA KDL40V2500, manufactured by Sony Corporation) and removing all the films attached to the liquid crystal cell, the absorption axis direction of the first polarizing plate is on the viewing side (front side). The said 1st composite polarizing plate was affixed through the pressure sensitive adhesive layer so that it might become parallel to the horizontal direction (longitudinal direction) of a liquid crystal television. Furthermore, on the opposite side (rear side) from the viewing side of the liquid crystal cell, the pressure-sensitive adhesive layer is interposed so that the absorption axis direction of the second polarizing plate is parallel to the vertical direction (short direction) of the liquid crystal television. The said 2nd composite polarizing plate was affixed and the liquid crystal display device was obtained.

  FIG. 6 is a graph showing the chromaticity distribution when the liquid crystal display device manufactured in Example 1 is displayed in black. The chromaticity distribution shown in FIG. 6 causes the liquid crystal display device to display black, and at an elevation angle of 0 °, 20 °, 40 °, 60 °, and 80 °, an azimuth angle of 0 °, 1 °, 2 °,. The color eyes when viewed from the angle are all plotted on the x and y chromaticity coordinates, and the smaller the variation in points, the smaller the variation in color depending on the viewing angle. For the measurement of color, a viewing angle measuring device (EZ-contrast 88XL, manufactured by ELDIM) was used. Note that an elevation angle of 0 ° is the normal direction of the screen, meaning that the inclination increases as the angle increases, the azimuth angle of 0 ° is the right direction of the screen, 90 ° is the upward direction of the screen, 180 ° is the left direction of the screen, and 270 ° means the screen downward direction. As a result, there was almost no change in color according to the viewing angle, and good viewing angle characteristics were obtained.

<Example 2>
KL-318 (manufactured by Kuraray Co., Ltd.), which is an anionic group-containing polyvinyl alcohol, is used as the polyvinyl alcohol-based resin, and ORGATICS TC-310 (Matsumoto Pharmaceutical Co., Ltd.), which is a water-soluble organic titanium compound, is used as a crosslinking agent. Manufactured as described above, referred to as “titanium lactate”, a solution of 44% active ingredient having a chemical structure of (HO) ₂ Ti [OCH (CH ₃ ) COOH], 40% isopropyl alcohol, 16% water) A primer layer coating solution was prepared by blending with the following composition.

・ Water 100 parts ・ Polyvinyl alcohol resin (KL-318) 3 parts ・ Organic titanium compound (Orgatics TC-310) 1.5 parts This coating liquid is mixed with polyvinyl alcohol resin while warming water to 80 ° C. Then, the mixture was cooled to room temperature after stirring, and a solution of an organic titanium compound was further added and mixed, followed by stirring. As described above, the organotitanium compound was obtained in the form of a solution, and the amount used in preparing the primer layer coating solution was shown by the weight of the solution itself.

  The same primer layer coating solution was applied to the polarizing film side surface of the second polarizing plate having triacetyl cellulose as a protective layer on one side, which was the same as that used in the preparation of the second composite polarizing plate in Example 1. And dried at 80 ° C. for about 1 minute to form a primer layer. On this primer layer, the same coating liquid for preparing the second retardation plate as used in Example 1 was applied in the same manner as in Example 1, dried, and then coated with the coating retardation layer (second retardation). Plate) and the pressure-sensitive adhesive layer on the separate film was transferred to prepare a second composite polarizing plate. The second composite polarizing plate was changed to the one produced here, and the others were produced in the same manner as in Example 1 and evaluated in the same manner. As a result, the same result as in Example 1 was obtained.

<Comparative Example 1>
The coating solution for preparing the second retardation plate prepared in the same manner as in Example 1 was dried on a triacetyl cellulose film (KC8UX2MW, manufactured by Konica Minolta Opto) so that the thickness after drying was 6.3 μm. Then, direct coating was performed with a desktop gap coater and dried at 80 ° C. for 2 minutes to form a coating retardation layer, and a second retardation plate composed of a triacetyl cellulose substrate / coating retardation layer was produced. This second retardation plate (with a substrate) had an in-plane retardation value R ₀ of 0.2 nm and a thickness direction retardation value R _th of 150 nm. The triacetylcellulose substrate side of the second retardation plate is bonded to the side where the polarizing film of the second polarizing plate having triacetylcellulose as a protective layer is exposed on the same side as used in Example 1. The pressure-sensitive adhesive layer (P-3132, manufactured by Lintec Co., Ltd.) formed on the separate film was further transferred to the coating retardation layer side to form a second composite polarizing plate. A liquid crystal display device was produced in the same manner as in Example 1 except that the second composite polarizing plate produced here was used instead of the second composite polarizing plate in Example 1.

  FIG. 7 is a graph showing the chromaticity distribution when the liquid crystal display device manufactured in Comparative Example 1 is displayed in black, and the display format is the same as FIG. From FIG. 7, it can be seen that the liquid crystal display device of Comparative Example 1 has a large difference in color depending on the viewing angle, and is inferior in viewing angle characteristics. The major difference between Example 1 or Example 2 and Comparative Example 1 is that, in Example 1 or Example 2, the refractive index differs between the polarizing film constituting the second polarizing plate and the second retardation plate by the coating. Whereas there is no layer having anisotropy, in Comparative Example 1, there is a layer having a refractive index anisotropy (triacetyl cellulose film: having a retardation value in the thickness direction). Therefore, according to the present invention, by adopting a configuration in which there is no layer having refractive index anisotropy between the polarizing film constituting the second polarizing plate and the second retardation plate by the coating, the viewing angle characteristics are improved. Improved.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The set of the composite polarizing plate of the present invention hardly changes the color even when the viewing angle is changed, can provide a good viewing angle characteristic, and is particularly useful for a vertical alignment mode liquid crystal display device.

It is a perspective view which shows typically the 1st composite polarizing plate 1 of a preferable example used for the composite polarizing plate set of this invention in the state which spaced apart each layer. It is a perspective view which shows typically the 1st composite polarizing plate 11 of the other preferable example used for the composite polarizing plate set of this invention in the state which spaced apart each layer. It is a perspective view which shows typically the 2nd composite polarizing plate 21 of a preferable example used for the composite polarizing plate set of this invention in the state which spaced apart each layer. It is a perspective view which shows typically the 2nd composite polarizing plate 31 of the other preferable example used for the composite polarizing plate set of this invention in the state which spaced apart each layer. FIG. 5 (a) is a cross-sectional view schematically showing an example of a liquid crystal display device manufactured using the composite polarizing plate set of the present invention, and FIG. 5 (b) shows the respective layers shifted from each other. It is a top view. 4 is a graph showing a chromaticity distribution when the liquid crystal display device manufactured in Example 1 is displayed in black. It is a graph which shows chromaticity distribution when the liquid crystal display device produced in the comparative example 1 is displayed in black.

Explanation of symbols

  1,11 First composite polarizing plate, 2,12 First polarizing plate, 3 First retardation plate, 4 Pressure sensitive adhesive layer, 5,25 Linear polarizing film, 6, 7, 26 Protective layer, 21, 31 1st Two composite polarizing plates, 22 Second polarizing plate, 23 Second retardation plate, 24 Pressure sensitive adhesive layer, 32 Primer layer, 50 Liquid crystal cell.

Claims (5)

A set of a first composite polarizing plate and a second composite polarizing plate used in a liquid crystal display device,
The first composite polarizing plate has a structure in which a first polarizing plate, a first retardation plate, and a pressure-sensitive adhesive layer are laminated in this order, and the first retardation plate has an in-plane retardation. There value R ₀ within the range of 90 to 200 nm, the refractive index in the in-plane slow axis direction n _x of the film, the refractive index in the in-plane fast axis direction n _y of the film, the refractive index in the thickness direction of the film N _z coefficient defined by the following formula when n _z is in the range of 0.8 to 1.5, and the slow axis direction and the absorption axis direction of the polarizing plate are angles of 80 to 100 ° Arranged to intersect at
The second composite polarizing plate has a structure in which a second polarizing plate, a second retardation plate, and a pressure-sensitive adhesive layer are laminated in this order, and the second polarizing plate is transparent on one side of the polarizing film. A protective film is laminated and a second retardation plate is laminated on the opposite side of the transparent protective film. The second retardation plate includes an organically modified clay composite and a binder resin, and is in-plane. The composite polarizing plate set has a retardation value R _{0 of 0} to 30 nm and a thickness direction retardation value R _th of 30 to 300 nm.
N _z factor _{= (n x -n z) /} (n x -n y)   The composite polarizing plate set according to claim 1, wherein the polarizing film of the second polarizing plate and the second retardation plate are directly bonded.   The composite polarizing plate set according to claim 1, wherein an optically isotropic primer layer is interposed between the polarizing film of the second polarizing plate and the second retardation plate.   The composite polarizing plate set according to claim 1, which is used in a vertical alignment mode liquid crystal display device.   A liquid crystal display device comprising the composite polarizing plate set according to claim 1 and a liquid crystal cell, wherein the first composite polarizing plate is pasted on one side of the liquid crystal cell via the pressure-sensitive adhesive layer. And a second composite polarizing plate is bonded to the other side of the liquid crystal cell via the pressure-sensitive adhesive layer.

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