JP2009139642A - Composite polarizing plate roll, composite polarizing plate set, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite polarizing plate set capable of improving characteristics of angle of visibility in a liquid crystal display device and to provide the liquid crystal display device using it. <P>SOLUTION: This composite polarizing plate set is composed of the first composite polarizing plate 1 constituted in such a way that a polarizing plate 2, a first phase difference plate 3, and a pressure sensitive adhesive layer 4 are sequentially laminated in this order. The first phase difference plate 3 is a phase difference film formed by drawing a propylene resin; its in-plane phase difference value R<SB>o</SB>is in a scope of 90-200 nm; its N<SB>z</SB>coefficient is in a scope of 0.90-1.10; and it is arranged to let its lagging axis cross the axial direction of absorption of the polarizing plate at an angle of 80-100°. The second composite polarizing plate is constituted in such a way that a polarizing plate, a second phase difference plate, and a pressure sensitive adhesive layer are sequentially laminated in this order. The second phase difference plate includes an organic modified clay composite and a binder resin; its inplane phase difference value R<SB>o</SB>is in a scope of 0-30 nm, and its phase difference value R<SB>th</SB>in the direction of thickness is in a scope of 30-300 nm. The liquid crystal display device using this set and the composite polarizing plate roll for the liquid crystal display device are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composite polarizing plate roll, 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 0.80 and 1.50 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. In the case of fixed-end lateral uniaxial stretching, the film often has a slight biaxiality of about 1.10 <N _z coefficient ≦ 1.50. A retardation film having such an N _z coefficient may be uniaxial but may not be completely uniaxial. The completely uniaxial retardation film here refers to a film in the range of 0.90 ≦ N _z coefficient ≦ 1.10.

Although the viewing angle of the VA mode has been considerably widened by using various retardation films as disclosed in Patent Document 1, it is said that there is still room for improvement.
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 VA mode liquid crystal display device, the present inventor found that a uniaxial retardation film is a combination of a uniaxial retardation film and a complete biaxial retardation film. The present inventors have found that a liquid crystal display device with further excellent viewing angle characteristics can be obtained by making the optical characteristics completely uniaxial. That is, the present invention is as follows.

The present invention has a structure in which a long roll of a first retardation plate is laminated on a long roll of a polarizing plate whose absorption axis direction is arranged in parallel with the longitudinal direction, and the slow phase of the first retardation plate It is a composite polarizing plate roll arranged so that the axial direction and the absorption axis direction of the polarizing plate intersect at an angle of 80 to 100 °, and the first retardation plate is formed by stretching a propylene-based resin, in the range retardation value R ₀ of 90~200nm plane, and the in-plane slow axis direction of the refractive index of the film n _x, the in-plane fast axis direction of the refractive index of the film n _y, film n _z coefficient defined by the following formula refractive index in the thickness direction is taken as n _z of which lies in the range of 0.90 to 1.10.

N _z factor _{= (n x -n z) /} (n x -n y)
It is preferable that the 1st phase difference plate in the composite polarizing plate roll of this invention is a film obtained by carrying out fixed end lateral uniaxial stretching of propylene-type resin.

The present invention is also a set of a first composite polarizing plate and a second composite polarizing plate used in a liquid crystal display device, wherein the first composite polarizing plate is a polarizing plate, a first retardation plate, and a pressure-sensitive adhesive. The first retardation plate is a retardation film obtained by stretching a propylene-based resin, and the in-plane retardation value R ₀ is in the range of 90 to 200 nm. under there, and, when 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 was n _z in the There N _z coefficient defined by the expression in a range of 0.90 to 1.10, and 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 ° The second composite polarizing plate has a structure in which a polarizing plate, a second retardation plate, and a pressure-sensitive adhesive layer are laminated in this order, Retarder includes an organic modified clay complex and a binder resin, in the range retardation value R ₀ in 0~30nm in-plane retardation value in the thickness direction R _th in the range of 30~300nm A composite polarizing plate set is also provided.

N _z factor _{= (n x -n z) /} (n x -n y)
The first retardation plate in the composite polarizing plate set of the present invention is preferably a film obtained by stretching a propylene-based resin laterally uniaxially.

  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, even when the viewing angle is changed, a change in color is unlikely to occur, and a liquid crystal display device (particularly, a VA mode liquid crystal display device) capable of obtaining good viewing angle characteristics, a composite polarizing plate set therefor, In addition, a composite polarizing plate roll useful for a composite polarizing plate set 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. In the first composite polarizing plate and the second composite polarizing plate in the present invention, the polarizing plate, the retardation plate (first retardation plate or second retardation plate), and the pressure-sensitive adhesive layer are in this order. It has a laminated structure.

[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 polarizing plates 2 and 12 are partially different. 3 and a pressure-sensitive adhesive layer 4 are laminated.

The first retardation plate 3 used in the present invention is a retardation film formed by stretching a propylene-based resin, and has an in-plane retardation value R ₀ in the range of 90 to 200 nm. To do. That is, the first retardation plate 3 used in the present invention is a complete uniaxial retardation film (uniaxial film in the range of 0.90 ≦ N _z coefficient ≦ 1.10 as described above). In order to obtain such a positive complete uniaxial retardation film, it is usually sufficient to stretch and orient a resin film having a positive intrinsic birefringence. The stretching method includes fixed end uniaxial stretching and free end uniaxial stretching. Stretching can be applied.

Here, when continuous free end uniaxial stretching is performed on a long roll of film, a stretching method called longitudinal stretching in which the film is stretched in the longitudinal direction (flow direction) is used. The slow axis direction of the retardation film obtained by such a method is substantially parallel to the longitudinal direction of the film. The polarizing plate is also usually obtained by stretching a long roll of a film made of a polyvinyl alcohol-based resin by free-end longitudinal uniaxial stretching, and the absorption axis direction is substantially parallel to the longitudinal direction. When laminating these so that the slow axis direction of the retardation film and the absorption axis direction of the polarizing plate are orthogonal, at least one of the long rolls is cut out into a sheet shape with a certain size, After the direction is rotated by 90 degrees, it is necessary to bond the sheets one by one to the other film. On the other hand, in the case of a retardation film obtained by fixed-end lateral uniaxial stretching using a tenter or the like, the slow axis direction is a direction (width direction) orthogonal to the longitudinal direction of the long roll. The long roll and the long roll of the polarizing plate can be continuously bonded in a roll-to-roll manner. However, when the fixed-end transverse uniaxial stretching conventional amorphous resin film, completely uniaxial it is difficult to obtain a phase difference film, in many cases becomes N _z coefficient> 1.10.

  In the present invention, even when fixed-end lateral uniaxial stretching is performed, by using a propylene-based resin that can obtain completely uniaxial characteristics by stretching at a high magnification of a certain degree or more, it is possible to achieve complete uniaxiality. The first retardation plate 3 that is a retardation film is used. Here, the high magnification of a certain level is usually 2 times or more, preferably 3 times or more, more preferably 3.5 times or more. The upper limit of the draw ratio is not particularly limited, but if the film is stretched too much, the film may be broken. Therefore, the film is usually stretched 10 times or less, preferably 8 times or less, more preferably 6 times or less. The retardation film obtained by carrying out the fixed-end lateral uniaxial stretching has a slow axis direction substantially parallel to a direction different from the longitudinal direction of the film by 90 degrees (= width direction). A long roll of retardation film obtained by stretching is bonded with a long roll of a polarizing plate and a roll-to-roll to efficiently use the first composite polarizing plate used in the composite polarizing plate set of the present invention. It can be easily manufactured. In this sense, it is useful to use a film made of a propylene-based resin for the retardation film as in the present invention.

  The propylene-based resin used for the first retardation plate of the first composite polarizing plate in the present invention is a resin mainly composed of propylene units, which is generally crystalline, in addition to a propylene homopolymer. Further, it may be a copolymer of propylene and a comonomer copolymerizable therewith.

Examples of the comonomer copolymerized with propylene include ethylene and an α-olefin having 4 to 20 carbon atoms (C _{4 to} C ₂₀ ). Specific examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 2-methyl-1-propene (above C ₄ ); 1-pentene, 2-methyl-1-butene, and 3-methyl. -1-butene (above C ₅ ); 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4- Methyl-1-pentene, 3,3-dimethyl-1-butene (above C ₆ ); 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene 2-methyl-3-ethyl-1-butene (above C ₇ ); 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2- Methyl-3-ethyl-1-pentene, 2,3,4-tri Chill-1-pentene, 2-propyl-1-pentene, 2,3-diethyl-1-butene (or C _8); 1-nonene (C _9); 1-decene (C _10); 1-undecene (C ₁₁ ); 1-dodecene (C ₁₂ ); 1-tridecene (C ₁₃ ); 1-tetradecene (C ₁₄ ); 1-pentadecene (C ₁₅ ); 1-hexadecene (C ₁₆ ); 1-heptadecene (C ₁₇ ) 1-octadecene (C ₁₈ ); 1-nonadecene (C ₁₉ ) and the like.

  Among the α-olefins described above, α-olefins having 4 to 12 carbon atoms are preferable, and specifically, 1-butene, 2-methyl-1-propene; 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene; 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl- 1-pentene, 3,3-dimethyl-1-butene; 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl-3- Ethyl-1-butene; 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2, 3,4-trimethyl-1-pen And ten-, 2-propyl-1-pentene, 2,3-diethyl-1-butene; 1-nonene; 1-decene; 1-undecene; 1-dodecene, and the like. From the viewpoint of copolymerizability, at least one selected from 1-butene, 1-pentene, 1-hexene and 1-octene is preferable, and 1-butene and / or 1-hexene is more preferable.

  The copolymer may be a random copolymer or a block copolymer. Preferable copolymers include propylene-ethylene copolymers and propylene-1-butene copolymers. The content of ethylene units and the content of 1-butene units in propylene-ethylene copolymers and propylene-1-butene copolymers are described in, for example, page 616 of "Polymer Analysis Handbook" (1995, published by Kinokuniya Shoten). Infrared (IR) spectrum measurement can be performed by the method described.

  From the viewpoint of improving transparency and workability, it is preferable to use a random copolymer with an arbitrary unsaturated hydrocarbon mainly composed of propylene. Of these, a copolymer with ethylene is preferred. In the case of a copolymer, the unsaturated hydrocarbon other than propylene is advantageously 1 to 10% by weight, and more preferably 3 to 7% by weight. By setting the unit of unsaturated hydrocarbons other than propylene to 1% by weight or more, there is a tendency that an effect of improving processability and transparency appears. However, if the ratio exceeds 10% by weight, the melting point of the resin tends to decrease and the heat resistance tends to deteriorate, which is not preferable. When two or more kinds of comonomers are copolymerized with propylene, the total content of units derived from all comonomers contained in the obtained copolymer is preferably within the above-described range.

  The propylene-based resin can be produced by a method of homopolymerizing propylene, a method of copolymerizing propylene and another copolymerizable comonomer, or the like.

  These methods include, for example, (1) a titanium-magnesium (Ti-Mg) catalyst comprising a solid catalyst component containing magnesium, titanium and halogen as essential components, and (2) a solid containing magnesium, titanium and halogen as essential components. A known polymerization catalyst such as a catalyst system in which an organoaluminum compound and, if necessary, a third component such as an electron donating compound are combined with the catalyst component, or (3) a metallocene catalyst can be suitably used.

  Among the catalyst systems described above, the combination of an organic aluminum compound and an electron donating compound with a solid catalyst component containing magnesium, titanium and halogen as essential components is most commonly used. More specifically, the organoaluminum compound is preferably triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, tetraethyldialumoxane, etc., and the electron donating compound is preferably cyclohexylethyldimethoxy. Examples thereof include silane, tert-butylpropyldimethoxysilane, tert-butylethyldimethoxysilane, and dicyclopentyldimethoxysilane.

  On the other hand, examples of the solid catalyst component containing magnesium, titanium, and halogen as essential components include catalyst systems described in JP-A-61-218606, JP-A-61-287904, JP-A-7-216017, and the like. Examples of the metallocene catalyst include the catalyst systems described in Japanese Patent No. 2587251, Japanese Patent No. 2627669, Japanese Patent No. 2668732, and the like.

  Propylene-based resin is, for example, a solution polymerization method using an inert solvent typified by a hydrocarbon compound such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, or a bulk using a liquid monomer as a solvent. It can be produced by a polymerization method or a gas phase polymerization method in which a gaseous monomer is polymerized as it is. Polymerization by these methods may be carried out batchwise or continuously.

  The stereoregularity of the propylene-based resin may be any of isotactic, syndiotactic, and atactic. In the present invention, a syndiotactic or isotactic propylene resin is preferably used from the viewpoint of heat resistance.

  The propylene-based resin used in the present invention has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 21.18 N in accordance with JIS K 7210, 0.1 to 200 g / 10 min, especially 0.5. It is preferably in the range of ˜50 g / 10 minutes. By using a propylene resin having an MFR in this range, a uniform film can be obtained without imposing a large load on the extruder.

  The propylene-based resin may be blended with known additives as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an antifogging agent, and an antiblocking agent. Antioxidants include, for example, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hindered amine light stabilizers, and the like, and for example, phenolic antioxidant mechanisms and phosphorous compounds in one molecule. It is also possible to use a composite antioxidant having a unit having both of the above antioxidant mechanisms. Examples of the UV absorber include UV absorbers such as 2-hydroxybenzophenone and hydroxyphenylbenzotriazole, and benzoate UV blockers. The antistatic agent may be polymer type, oligomer type or monomer type. Examples of the lubricant include higher fatty acid amides such as erucic acid amide and oleic acid amide, higher fatty acids such as stearic acid, and salts thereof. Examples of the nucleating agent include a sorbitol nucleating agent, an organic phosphate nucleating agent, and a polymer nucleating agent such as polyvinylcycloalkane. As the anti-blocking agent, fine particles having a spherical shape or a shape close thereto can be used regardless of inorganic type or organic type. A plurality of these additives may be used in combination.

  In the present invention, the above-described propylene-based resin is formed into a film and used as a raw material for a retardation film. For example, a propylene-based material having substantially no in-plane retardation by extrusion molding from a molten resin, solvent casting method in which a resin dissolved in an organic solvent is cast on a flat plate, and the solvent is removed to form a film. A resin film can be obtained.

  A method for producing a film by extrusion will be described in detail. The propylene-based resin is melt-kneaded by rotation of a screw in an extruder and extruded from a T die into a sheet. The temperature of the extruded molten sheet is 180 to 300 ° C. If the temperature of the molten sheet at this time is lower than 180 ° C., the spreadability is not sufficient, the thickness of the obtained film becomes non-uniform, and there is a possibility that the film has a phase difference unevenness. Further, when the temperature exceeds 300 ° C., the resin is easily deteriorated or decomposed, and bubbles may be generated in the sheet or carbides may be contained.

  The extruder may be a single screw extruder or a twin screw extruder. For example, in the case of a single screw extruder, L / D, which is the ratio of the screw length L to the diameter D, is about 24 to 36, the screw groove space volume in the resin supply unit, and the screw groove space volume in the resin metering unit. The compression ratio, which is the ratio (the former / the latter), is about 1.5 to 4, and a screw of a full flight type, a barrier type, or a type having a Maddock type kneading portion can be used. From the viewpoint of suppressing the deterioration and decomposition of the propylene-based resin and uniformly melting and kneading, it is necessary to use a barrier type screw having an L / D of 28 to 36 and a compression ratio of 2.5 to 3.5. preferable. In order to suppress deterioration and decomposition of the propylene resin as much as possible, the inside of the extruder is preferably a nitrogen atmosphere or a vacuum. Furthermore, in order to remove volatile gas generated by the deterioration or decomposition of the propylene-based resin, it is also preferable to provide an orifice having a diameter of 1 to 5 mm at the tip of the extruder to increase the resin pressure at the tip of the extruder. Increasing the resin pressure at the tip of the extruder at the orifice means increasing the back pressure at the tip, thereby improving the stability of extrusion. The diameter of the orifice used is more preferably 2 to 4 mm in diameter.

  The T-die used for extrusion preferably has no fine steps or scratches on the surface of the resin flow path, and its lip portion is plated or coated with a material having a low coefficient of friction with the molten propylene resin. Further, a sharp edge shape having a lip tip polished to a diameter of 0.3 mm or less is preferable. Examples of the material having a small friction coefficient include tungsten carbide type and fluorine type special plating. By using such a T-die, it is possible to suppress the generation of eyes and simultaneously suppress the die line, so that a resin film having excellent appearance uniformity can be obtained. In the T-die, the manifold has a coat hanger shape and preferably satisfies the following condition (1) or (2), and more preferably satisfies the condition (3) or (4).

・ Condition (1)
When the lip width of the T die is less than 1500 mm: T die thickness direction length> 180 mm
・ Condition (2)
When the lip width of the T die is 1500 mm or more: length of the T die in the thickness direction> 220 mm
・ Condition (3)
When the lip width of the T die is less than 1500 mm: the length of the T die in the height direction> 250 mm
・ Condition (4)
When the lip width of the T die is 1500 mm or more: Length of the T die in the height direction> 280 mm
By using a T die that satisfies such conditions, the flow of the molten propylene-based resin inside the T die can be adjusted, and the lip portion can be extruded while suppressing thickness unevenness, so that the thickness is increased. A protective film having excellent accuracy and a more uniform retardation can be obtained.

  From the viewpoint of suppressing the extrusion fluctuation of the propylene-based resin, it is preferable to attach a gear pump via an adapter between the extruder and the T die. In addition, it is preferable to attach a leaf disk filter to remove foreign substances in the propylene-based resin.

  The molten sheet extruded from the T-die is between a metal cooling roll (also referred to as a chill roll or a casting roll) and a touch roll including an elastic body that rotates by pressing in the circumferential direction of the metal cooling roll. A desired film can be obtained by clamping and solidifying by cooling. In this case, the touch roll may be one in which an elastic body such as rubber is directly on the surface, or may be one in which the surface of the elastic body roll is covered with an outer cylinder made of a metal sleeve. When using a touch roll in which the surface of the elastic roll is covered with an outer cylinder made of a metal sleeve, cooling is usually performed by directly sandwiching a molten sheet of propylene resin between the metal cooling roll and the touch roll. On the other hand, in the case of using a touch roll whose surface is an elastic body, a biaxially stretched film of a thermoplastic resin can be interposed between the molten sheet of propylene-based resin and the touch roll.

  When the molten sheet of propylene-based resin is cooled and solidified by being sandwiched between the cooling roll and the touch roll described above, both the cooling roll and the touch roll have their surface temperatures lowered, and the molten sheet is rapidly cooled. I need to do it. Specifically, the surface temperature of both rolls is adjusted to a range of 0 to 30 ° C. If these surface temperatures exceed 30 ° C., it takes time to cool and solidify the molten sheet, so that the crystal component in the propylene resin grows, and the resulting film may be inferior in transparency. . On the other hand, when the surface temperature of the roll is less than 0 ° C., the surface of the metal cooling roll is dewed and water droplets adhere to it, which tends to deteriorate the appearance of the film.

  Since the surface state of the metal cooling roll to be used is transferred to the surface of the propylene-based resin film, there is a possibility that the thickness accuracy of the resulting propylene-based resin film is lowered when the surface has irregularities. Therefore, it is preferable that the surface of the metal cooling roll is in a mirror surface state as much as possible. Specifically, the roughness of the surface of the metal cooling roll is preferably 0.3 S or less, more preferably 0.1 to 0.2 S, expressed in a standard sequence of the maximum height. .

  The touch roll that forms the nip portion with the metal cooling roll has a surface hardness of 65 to 80 as a value measured by a spring type hardness test (A type) defined in JIS K 6301. Is more preferable, and 70 to 80 is more preferable. By using a rubber roll having such a surface hardness, it becomes easy to maintain a uniform linear pressure applied to the molten sheet, and a bank of the molten sheet (resin pool) is provided between the metal cooling roll and the touch roll. ) Can be easily formed into a film.

  The pressure (linear pressure) when sandwiching the molten sheet is determined by the pressure for pressing the touch roll against the metal cooling roll. The linear pressure is preferably 50 to 300 N / cm, and more preferably 100 to 250 N / cm. By setting the linear pressure within the above range, it becomes easy to produce a propylene-based resin film while maintaining a constant linear pressure without forming a bank.

  When a biaxially stretched film of a thermoplastic resin is sandwiched between a metal cooling roll and a touch roll together with a molten sheet of propylene resin, the thermoplastic resin constituting the biaxially stretched film is strong with the propylene resin. Any resin may be used as long as it is not heat-sealed, and specific examples include polyester, polyamide, polyvinyl chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and polyacrylonitrile. Among these, polyesters that have little dimensional change due to humidity, heat, and the like are most preferable. In this case, the thickness of the biaxially stretched film is usually about 5 to 50 μm, preferably 10 to 30 μm.

  In this method, the distance (air gap) from the lip of the T die to the pressure between the metal cooling roll and the touch roll is preferably 200 mm or less, and more preferably 160 mm or less. The molten sheet extruded from the T-die is stretched from the lip to the roll, and orientation tends to occur. By shortening the air gap as described above, a film having a smaller orientation can be obtained. The lower limit value of the air gap is determined by the diameter of the metal cooling roll to be used, the diameter of the touch roll, and the tip shape of the lip to be used, and is usually 50 mm or more.

  The processing speed when producing a propylene-based resin film by this method is determined by the time required for cooling and solidifying the molten sheet. When the diameter of the metal cooling roll to be used is increased, the distance at which the molten sheet is in contact with the cooling roll becomes longer, so that production at a higher speed is possible. Specifically, when a metal cooling roll having a diameter of 600 mm is used, the processing speed is about 5 to 20 m / min at the maximum.

  The molten sheet sandwiched between the metal cooling roll and the touch roll is cooled and solidified by contact with the roll. And after slitting an edge part as needed, it is wound up by a winder and becomes a film. Under the present circumstances, in order to protect the surface until it uses a film, you may wind up in the state which bonded the surface protection film which consists of another thermoplastic resin to the single side | surface or both surfaces. When a molten sheet of propylene resin is sandwiched between a metal cooling roll and a touch roll together with a biaxially stretched film made of a thermoplastic resin, the biaxially stretched film is used as one surface protective film. You can also.

As described above, the first retardation plate used in the first composite polarizing plate of the present invention has an in-plane retardation value R ₀ 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.

First retardation plate used in the first composite polarizing plate of the present invention, further, the in-plane slow axis direction of the refractive index of the film n _x, the in-plane fast axis direction of the refractive index of the film n _y, n _z coefficient defined by the following formula refractive index in the thickness direction is taken as n _z of the film also one of the features that are within the scope of 0.90 to 1.10.

N _z factor _{= (n x -n z) /} (n x -n y)
Since the first retardation plate used in the present invention aims to be completely uniaxial as described above, its N _z coefficient is set to be in the range of 0.90 to 1.10. N _z coefficient by stretching it is difficult to form a film below 0.90. On the other hand, when N _z coefficient exceeds 1.10, the contrast viewing angle of the liquid crystal display device is reduced wearing it. Incidentally, the first of in-plane slow axis direction of the refractive indices n _x of the film retardation plate, the refractive index in the in-plane fast axis direction n _y, the refractive index n _z and N _z coefficient in the thickness direction in the present invention, As described above, it refers to a value measured using, for example, an automatic birefringence measuring apparatus KOBRA-21ADH (manufactured by Oji Scientific Instruments).

  In addition, the polarizing plate used for the first composite polarizing plate in the present invention can be one generally used in the art, for example, a dichroic dye (iodine, dichroic organic) to polyvinyl alcohol resin. Generally used is a structure in which a protective layer made of a resin film such as a triacetyl cellulose resin, a cyclic cycloolefin resin, or a chain cycloolefin resin is laminated on one or both sides of a linearly polarizing film on which a dye or the like is adsorbed and oriented. It is done. FIG. 1 shows a case where a polarizing plate 2 having protective layers 6 and 7 provided on both sides of a linearly polarizing film 5 is used, and FIG. The case where the polarizing plate 12 in which the protective layer 6 was provided in the surface on the opposite side to the side where the phase difference plate 3 was laminated | stacked is shown.

  In the first composite polarizing plate of the present invention, the first retardation is arranged in such a manner that the slow axis direction of the first retardation plate and the absorption axis direction of the polarizing plate intersect at an angle of 80 to 100 °. A plate and a polarizing plate are laminated. If the angle formed by the slow axis direction of the first retardation plate and the absorption axis direction of the polarizing plate is out of this range, the liquid crystal display device on which it is mounted causes light leakage during black display and reduces 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 °.

  As the pressure-sensitive adhesive (adhesive) layer 4 formed on the side opposite to the side adjacent to the polarizing plates 2 and 12 of the first retardation plate 3 in the first composite polarizing plates 1 and 11, a liquid crystal display has been conventionally used. It can be formed using various pressure-sensitive adhesives that have been used for devices, such as pressure-sensitive adhesives such as acrylic, rubber-based, urethane-based, silicone-based, and polyvinyl ether, among others, transparency and weather resistance. A pressure sensitive adhesive having an acrylic resin having excellent heat resistance as a base polymer 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 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 separator that has been subjected to a release treatment such as silicone. After forming the pressure-sensitive adhesive layer on the separator, it may be transferred to the first retardation plate 3 and laminated. Moreover, when forming a pressure sensitive adhesive layer in a polarizing film, you may perform an adhesion | attachment process, for example, a corona treatment, etc. to at least one of a 1st phase difference plate and a pressure sensitive adhesive layer as needed. The surface of the formed pressure-sensitive adhesive layer is usually protected with a separator film that has been subjected to a release treatment, and the separator film is applied with the composite polarizing plate set of the present invention to a liquid crystal cell as described later. It is peeled off before joining.

  In the first composite polarizing plate of the present invention, for example, an epoxy resin, a urethane resin, or a cyanoacrylate 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 a resin such as an acryl resin or an acrylamide resin 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.

  A 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 the two are bonded together to form a polarizing plate. 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 (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, etc. Can be mentioned.

  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 using a cationic photopolymerization initiator, 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 has the advantage that the protective film can be satisfactorily adhered. is there. 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 adhesive is used, the method for applying 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 coater, a comma Various systems such as a 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.

  In addition, it is preferable to give a corona discharge process to 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.

[2-2] Second Composite Polarizing Plate Here, 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. 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 plates 21 and 31 shown in FIGS. 3 and 4 have the same structure except that the configurations of the polarizing plates 22 and 32 are partially different. 23 and a pressure-sensitive adhesive layer 24 are laminated.

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. Among these, urethane resin is preferable because the dispersibility of the organically modified clay complex 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 dispersed 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 substrate on which the coating liquid is applied is not particularly limited as long as the in-plane retardation value R _{0 is} substantially zero, but is not limited to an unstretched film made of a chain olefin resin, or a cycloolefin resin. An unstretched film made of a cellulose acylate resin or the like is preferable.

  When forming the second composite polarizing plate as shown in FIG. 3, this base material may also serve as the protective layer 27 of the polarizing plate 22. In this case, after the coating liquid described above is applied on the protective layer 27 to form the second retardation plate 23, the protective layer 27 with the second retardation plate 23 may be bonded to the polarizing film 25. Alternatively, the second retardation plate 23 may be formed by applying the above-described coating liquid to the protective layer 27 side of the polarizing film 25 to which the protective layer 27 is bonded in advance. In this case, a primer layer may be formed between the second retardation plate 23 and the protective layer 27.

  Further, the polarizing plate used for the second composite polarizing plate in the present invention can also be one generally used in this field, like the polarizing plate used for the first composite polarizing plate. Resin film such as triacetyl cellulose resin, cyclic cycloolefin resin, and chain cycloolefin resin on both sides or one side of linear polarizing film with dichroic dye (iodine, dichroic organic dye, etc.) adsorbed and oriented on resin A structure in which a protective layer made of is laminated is generally used. FIG. 3 shows a case where the polarizing plate 22 having protective layers 26 and 27 provided on both sides of the linear polarizing film 25 is used, and FIG. The case where the polarizing plate 32 in which the protective layer 26 was provided in the surface on the opposite side to the side where the phase difference plate 23 was laminated | stacked is shown.

  The pressure-sensitive adhesive layer 24 formed on the second composite polarizing plate 21, 31 in the present invention on the side opposite to the side adjacent to the polarizing plates 22, 32 of the second retardation plate 23 is the first composite polarizing plate 1. 11 can be formed using various pressure-sensitive adhesives conventionally used for liquid crystal display devices in the same manner as described above for the pressure-sensitive adhesive layer 4. In the second composite polarizing plate, the protective layer and the polarizing film, the protective layer or the adhesive between the polarizing film and the second retardation plate is bonded to the protective layer and the polarizing film, the protective layer or the polarizing plate in the first composite polarizing plate. The above-mentioned adhesives that are preferably used for bonding with the film first retardation plate are also preferably used.

  FIG. 5A is a cross-sectional view schematically showing an example of manufacturing an example of a liquid crystal display device manufactured using the set of composite polarizing plates of the present invention, and FIG. It is a top view shown in the state. 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 vertical alignment mode liquid crystal display device, as shown in FIG. 5B, the first composite polarizing plate 1 has a liquid crystal cell on the viewing side (front side) where the absorption axis direction 2a of the polarizing plate 2 is liquid crystal. Arranged so as to be parallel to the horizontal direction (longitudinal direction) of the cell, and further arranged so that the absorption axis direction 2a of the polarizing plate 2 and the slow axis direction 3a of the first retardation plate 3 intersect each other substantially perpendicularly. And pasted. Further, the second composite polarizing plate 21 is arranged so that the absorption axis direction 22a of the 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. Further, the polarizing plate 22 is disposed and pasted so that the absorption axis direction 22a of the polarizing plate 22 intersects the absorption axis direction 2a of the 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.

[2] Liquid Crystal Display Device In the present invention, 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 disposed on one side of the liquid crystal cell. Also provided is a liquid crystal display device in which a second composite polarizing plate is disposed on the other side of the liquid crystal cell. In this liquid crystal display device, the first composite polarizing plate is bonded to the liquid crystal cell via the pressure-sensitive adhesive layer, and the second composite polarizing plate is also bonded to the liquid crystal cell via the pressure-sensitive adhesive layer. . 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.

[3] Composite polarizing plate roll The present invention also has a structure in which the long roll of the first retardation plate is laminated on the long roll of the polarizing plate in which the absorption axis direction is arranged parallel to the longitudinal direction, A composite polarizing plate roll disposed so that a slow axis direction of a first retardation plate and an absorption axis direction of a polarizing plate intersect at an angle of 80 to 100 °, wherein the first retardation plate is propylene it extends the system resin, in the range retardation value R ₀ of 90~200nm plane, and the in-plane slow axis direction of the refractive index of the film n _x, plane fast axis direction of the film Also provided is a composite polarizing plate roll having an N _z coefficient in the range of 0.90 to 1.10, where n _{y is} the refractive index of the film and n _z is the refractive index in the thickness direction of the film. Such a composite polarizing plate roll of this invention can be used suitably in order to manufacture the 1st composite polarizing plate in the set of the composite polarizing plate of this invention mentioned above.

  The long roll of the first retardation plate in the composite polarizing plate roll of the present invention is fixed by using a propylene-based resin as described above for the first retardation plate of the first composite polarizing plate in the present invention. Even when end lateral uniaxial stretching is performed, complete uniaxial characteristics can be obtained by stretching at a certain high magnification. For this reason, it is preferable that the 1st phase difference plate in the composite polarizing plate roll of this invention is a film obtained by carrying out fixed end lateral uniaxial stretching of propylene-type resin, and, thereby, in the composite polarizing plate roll of this invention Since the slow axis direction of the first retardation plate is almost parallel to the direction (= width direction) different from the longitudinal direction of the film by 90 degrees, it can be easily pasted with a long roll and roll-to-roll of the polarizing plate. It can be manufactured. By cutting the composite polarizing plate roll of the present invention thus manufactured into an appropriate size, the first composite polarizing plate used for the set of the composite polarizing plate of the present invention described above is easily manufactured. .

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, “parts” and “%” representing amounts used or contents are based on weight unless otherwise specified. In-plane retardation value R ₀ , thickness direction retardation value R _th , and N _z coefficient are all measured using an automatic birefringence measuring device KOBRA-21ADH (manufactured by Oji Scientific Instruments). Value.

<Example 1>
(Preparation of Sample 1 of First Composite Polarizing Plate)
A polypropylene resin film (Sumitomo Nobrene W151, manufactured by Sumitomo Chemical Co., Ltd.) is formed to obtain a film having a thickness of 40 μm, and then a fixed-end lateral uniaxial stretching, and a first retardation plate that is a complete uniaxial retardation film Got. A polarizing plate having triacetyl cellulose as a protective layer 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 polarizing plate They were bonded together with an adhesive in a state where they were arranged so as to intersect with the slow axis direction of the phase difference 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 polarizing plate of the first retardation plate is adjacent, Sample 1 of one composite polarizing plate was produced. The in-plane retardation value R ₀ of the first retardation plate was 140 nm, and the N _z coefficient was 1.00.

(Production of Sample 1 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 weight ratio of the solid content of the organically modified clay complex / binder resin in this coating solution was 6/4.

The coating solution prepared as described above was directly applied on a triacetylcellulose film (KC8UX2MW, manufactured by Konica Minolta Co., Ltd.) with a desktop gap coater so that the thickness after drying was 6.3 μm. The coating retardation layer was formed by drying at 2 ° C. for 2 minutes to obtain a second retardation plate. The obtained second retardation plate had an in-plane retardation value R ₀ of 0.2 nm and a thickness direction retardation value R _th of 170 nm.

  The second retardation plate is bonded to the triacetylcellulose surface side with an adhesive on the side of the polarizing plate where the polarizing film of the polarizing plate having triacetylcellulose as a protective layer is exposed on one surface. The pressure-sensitive adhesive layer (P-3132, manufactured by Lintec Corporation) formed on the separate film was transferred onto the plate to obtain Sample 1 of the second composite polarizing plate.

(Liquid crystal display device)
After disassembling a commercially available liquid crystal television (BRAVIA KDL40V2500, manufactured by Sony Corporation) and removing all the film attached to the liquid crystal cell, the absorption axis direction of the polarizing plate is on the viewing side (front side). Sample 1 of the first composite polarizing plate was pasted via a pressure-sensitive adhesive layer so as to be parallel to the horizontal direction (longitudinal direction). Furthermore, the second composite polarizing plate is interposed via a pressure-sensitive adhesive layer so that the absorption axis direction is parallel to the vertical direction (short direction) of the liquid crystal television on the opposite side (rear side) to the viewing side of the liquid crystal cell. Sample 1 was attached with a polarizing plate to obtain a liquid crystal display device.

<Comparative Examples 1-4>
A norbornene resin film (ZEONOR, manufactured by Optes Co., Ltd.), which is a cycloolefin resin, is stretched uniaxially at a fixed end, and has first in-plane retardation values R ₀ and N _z coefficients as shown in Table 1. Samples 2 to 5 of the first composite polarizing plate were prepared in the same manner as in Example 1 except that a retardation plate was prepared and each of them was used. Further, the same as in Example 1 except that second retardation plates having in-plane retardation values R ₀ and thickness direction retardation values R _th as shown in Table 2 were prepared and used respectively. Thus, samples 2 to 5 of the second composite polarizing plate were produced. Liquid crystal display devices of Comparative Examples 1 to 4 were produced in the same manner as in Example 1 except that the samples of the first composite polarizing plate and the sample of the second composite polarizing plate were combined as shown in Table 3. .

<Evaluation test>
As an evaluation test of the liquid crystal display devices obtained in Example 1 and Comparative Examples 1 to 4, using a viewing angle measuring device (EZ-contrast 88XL, manufactured by ELDIM), contrast ratio when displaying white and black The CR (contrast) viewing angle was measured as the angle range of the elevation angle where (= brightness during white display / brightness during black display) is 100 or more in the azimuth angle 45 degree direction. Table 3 also shows the measurement results of the CR viewing angle.

FIG. 6 is a graph showing the relationship between the N _z coefficient of the first retardation plate of the liquid crystal display devices obtained in Example 1 and Comparative Examples 1 to 4, and the CR viewing angle. From FIG. 6, it can be seen that when a completely uniaxial retardation film is used as the first retardation plate, good viewing angle characteristics are obtained. On the other hand, even if it is a uniaxial retardation film, it turns out that the viewing angle characteristic is getting worse by being slightly biaxial.

  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. It is a graph which shows the relationship between _Nz coefficient of the 1st phase difference plate of the liquid crystal display device obtained in Example 1, and Comparative Examples 1-4, and contrast viewing angle.

Explanation of symbols

  1,11 first composite polarizing plate, 2,12 polarizing plate, 3 first retardation plate, 4 pressure sensitive adhesive layer, 5,25 linear polarizing film, 6, 7, 26, 27 protective layer, 21, 31 first Two composite polarizing plates, 22, 32 polarizing plates, 23 second retardation plate, 24 pressure-sensitive adhesive layer, 50 liquid crystal cell.

Claims (6)

It has a structure in which a long roll of a first retardation plate is laminated on a long roll of a polarizing plate in which the absorption axis direction is arranged in parallel with the longitudinal direction, and the slow axis direction and polarization of the first retardation plate A composite polarizing plate roll arranged so that the absorption axis direction of the plate intersects at an angle of 80 to 100 °,
The first retardation plate made by stretching a propylene resin, in the range retardation value R ₀ of 90~200nm plane, and the in-plane slow axis direction of the refractive index of the film n _x, n _z coefficient defined by the following equation refractive index n _y in-plane fast axis direction, a refractive index in the thickness direction of the film when formed into a n _z of the film is in the range of 0.90 to 1.10 , Composite polarizing roll.
N _z factor _{= (n x -n z) /} (n x -n y)   The composite polarizing plate roll according to claim 1, wherein the first retardation plate is a film obtained by transversely uniaxially stretching a propylene-based resin. 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 polarizing plate, a first retardation plate, and a pressure-sensitive adhesive layer are laminated in this order. The first retardation plate is formed by stretching a propylene-based resin. a retardation film comprising, in the range that the retardation value R ₀ of 90~200nm plane, and the in-plane slow axis direction of the refractive index of the film n _x, plane fast axis direction of the film N _z coefficient defined by the following equation is in the range of 0.90 to 1.10, and the slow axis direction is N _y , where n is the refractive index of the film and _nz is the refractive index in the thickness direction of the film. And the absorption axis direction of the polarizing plate are arranged so as to intersect at an angle of 80 to 100 °,
The second composite polarizing plate has a structure in which a polarizing plate, a second retardation plate, and a pressure-sensitive adhesive layer are laminated in this order. The second retardation plate is composed of an organically modified clay composite and a binder. A composite polarizing plate set including an in-plane retardation value R ₀ in a range of ₀ to 30 nm and a thickness direction retardation value R _th in a range of 30 to 300 nm.
N _z factor _{= (n x -n z) /} (n x -n y)   The composite polarizing plate set according to claim 3, wherein the first retardation plate is a film obtained by transversely uniaxially stretching a propylene-based resin.   The composite polarizing plate set according to claim 3, 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 3 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 bonded to the other side of the liquid crystal cell via the pressure-sensitive adhesive layer.

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