TWI490559B - Composite polarizing plate and tn mode liquid crystal panel - Google Patents

Description

Composite polarizing plate and TN mode liquid crystal panel

The present invention relates to a composite polarizing plate and a TN mode liquid crystal panel which is used in a liquid crystal display device having a TN (Twisted Nematic) liquid crystal cell using the composite polarizing plate.

The liquid crystal cell of the TN mode encloses a nematic liquid crystal between two transparent substrates, and the nematic liquid crystal is twisted at 90° between the two transparent substrates without applying a voltage. Director. The nematic liquid crystal is oriented in the normal direction of the substrate in a state where a voltage is applied between the two transparent substrates. In a liquid crystal display device having a liquid crystal cell of a TN mode, by using such a change in the orientation state of the liquid crystal when no voltage is applied and when a voltage is applied, by arranging a pair of polarizing plates on the outer side of the two transparent substrates, the control is performed. Light penetration and shadowing to display an image. As described above, the TN mode liquid crystal cell structure is relatively simple and can be easily manufactured. Therefore, the TN mode liquid crystal panel and the TN mode liquid crystal display device in which the TN mode liquid crystal cell is incorporated are widely used as monitors for personal computers. use.

However, in the TN mode liquid crystal display device, for example, when the screen is viewed from an oblique direction, there is a disadvantage that the contrast is sharply lowered, or the viewing angle characteristics such as brightness or hue inversion are inferior in the oblique direction.

Therefore, in order to improve the disadvantages of such a TN mode liquid crystal display device, it is known to use an optical compensation film in which a discotic liquid crystal is oriented under specific conditions. For example, it is disclosed on the transparent support, specifically on a triacetyl cellulose film, by means of a dish shape, in Japanese Laid-Open Patent Publication No. 7-119217 (Patent Document 1). A discotic compound such as a liquid crystal is oriented, and an optically anisotropic element (optical compensation film) whose optical axis is optically negative uniaxial and whose optical axis is inclined from the normal direction of the film by 5 to 50°, and then The polarizing elements are combined to form a circularly polarizing plate. In recent years, such kinds of optical compensation films are often used in TN mode liquid crystal display devices.

However, since the above-mentioned optical compensation film uses a triethylenesulfonated cellulose film as a base material, the dimensional change in a high-temperature environment may be large, and heat resistance may be inferior. Therefore, in a liquid crystal display device using such an optical compensation film, light leakage occurs at the end of the liquid crystal display screen after being exposed to a high temperature environment, and sometimes it is not possible to sufficiently correspond to a desired brightness or contrast. The display quality required by the market.

An object of the present invention is to provide a composite polarizing plate which can suppress light leakage after a liquid crystal display device is exposed to a high temperature environment, and a TN mode liquid crystal panel using the polarizing plate.

Further, an object of the present invention is to provide a TN mode liquid crystal panel for a liquid crystal display device which is excellent in heat resistance in a high temperature environment and has a wide viewing angle in a lateral direction.

The composite polarizing plate of the present invention is obtained by sequentially laminating a transparent protective layer, a polarizer, a biaxial retardation film composed of an olefin resin, and an adhesive layer, and is characterized in that the olefin resin is used. The biaxial retardation film is composed of the following formula when the refractive indices in the in-plane slow axis direction, the in-plane fast axis direction, and the thickness direction measured by light having a wavelength of 590 nm are n _x , n _{y ,} and n _z , respectively. (I) The in-plane phase difference R ₀ defined is 40 to 150 nm, and the phase difference R _{th in} the thickness direction defined by the following formula (II) is 50 to 250 nm, which is defined by the following formula (III). _{The z} coefficient is more than 1 and is 7 or less, and the aforementioned adhesive layer exhibits a storage elastic modulus of 0.15 to 10 MPa in 23 to 80 ° C;

R ₀ =(n _x -n _y )×d (I)

R _th =[(n _x +n _y )/2-n _z ]×d (II)

N _z = (n _{x -} n _z ) / (n _{x -} n _y ) (III).

The present invention also provides a TN mode liquid crystal panel which is attached to the composite polarizing plate via the adhesive layer on both sides of the TN mode liquid crystal cell.

In the composite polarizing plate of the present invention, in the optical compensation film, a biaxial retardation film having a specific phase difference range composed of an olefin resin is used instead of the conventional triacetyl fluorene substrate. In the case where the disk-shaped liquid crystal is oriented, the adhesive layer used in bonding with the liquid crystal cell is an adhesive having a specific range of viscoelastic properties. Thereby, the composite polarizing plate suppresses dimensional change in a high temperature environment. Therefore, the composite polarizing plate is applied to a liquid crystal panel of a TN mode liquid crystal cell, and even if a TN mode liquid crystal display device using the same is exposed to a high temperature environment, it has an effect of preventing light leakage and maintaining good display quality.

The present invention also provides a TN mode liquid crystal panel in which a transparent protective layer, a polarizer, a biaxial retardation film composed of an olefin resin, and a composite layer polarized with an adhesive layer are sequentially laminated. The plate is formed by laminating the retardation film side of the composite polarizing plate on the both sides of the TN mode liquid crystal cell so as to face the liquid crystal cell side; and the biaxial phase composed of the olefin resin When the refractive index of the in-plane slow axis direction, the in-plane fast axis direction, and the thickness direction measured by light having a wavelength of 590 nm is n _x , n _{y ,} and n _z , respectively, the difference film is defined by the following formula (I). The in-plane phase difference value R ₀ is 40 to 150 nm, and the phase difference R _{th in} the thickness direction defined by the following formula (II) is 50 to 250 nm, and the N _z coefficient defined by the following formula (III) is more than 1 and 7 or less,

R ₀ =(n _x -n _y )×d (I)

R _th =[(n _x +n _y )/2-n _z ]×d (II)

N _z =(n _x -n _z )/(n _x -n _y ) (III)

When the in-plane phase difference value when the voltage is not applied to the liquid crystal cell is R _c , the following formulas (1) and (2) are satisfied:

0.13<R ₀ /R _c ≦0.34 (1)

0.17≦R _th /R _c <0.54 (2).

Thereby, it is possible to provide a TN mode liquid crystal panel which is excellent in heat resistance in a high temperature environment and has a wide viewing angle in the lateral direction.

In the TN mode liquid crystal panel of the present invention, the retardation film is preferably composed of a cyclic olefin resin.

In the TN mode liquid crystal panel of the present invention, the transparent protective layer in the composite polarizing plate disposed on at least one side of the liquid crystal cell is extended and has a thickness of 20 to 50 μm and has 0.1 to 40%. It is preferred that the haze value of the polyethylene terephthalate film is formed.

In the TN mode liquid crystal panel of the present invention, the transparent protective layer in the composite polarizing plate disposed on one side of the liquid crystal cell is a cyclic olefin resin film which is not extended and has a thickness of 15 to 25 μm. The constituents are better.

In the TN mode liquid crystal panel of the present invention, it is preferred that the polarizer and the transparent protective layer and/or the polarizer and the retardation film are followed by a solventless epoxy-based adhesive. In this case, it is preferred that the solventless epoxy-based adhesive is cured by cationic polymerization by irradiation with an active energy ray.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the accompanying drawings.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as needed.

[Composite polarizer]

Fig. 1 is an exploded perspective view schematically showing a TN mode liquid crystal panel 1 using a composite polarizing plate 2 of a preferred example of the present invention. The composite polarizing plate 2 of the present invention is composed of a transparent protective layer 4, a polarizer 3, a retardation film 5, and an adhesive layer 6.

[Polarizer]

The polarizer 3 is composed of a polyvinyl alcohol-based resin, which is generally used in the field. Specifically, it is possible to use a polyvinyl alcohol-based resin to be adsorbed, and to impart a linear polarized light that absorbs a vibration surface having a certain direction and a linear polarized light having a vibration surface having a direction orthogonal thereto. The function of the linear polarizer. The dichroic dye system uses iodine or a dichroic organic dye. In general, such a polarizer can be obtained by uniaxial stretching of a polyvinyl alcohol-based resin film, dyeing with a dichroic dye, and boric acid treatment after dyeing.

[Transparent protective layer]

The transparent protective layer 4 disposed on one side of the polarizer 3 is represented by, for example, triethyl fluorenyl cellulose (TAC) or diethyl fluorene cellulose which is generally used as a protective layer of a polarizer. The film of the fluorenyl cellulose-based resin is advantageous. However, a film of a cyclic olefin resin represented by a norbornene resin, a film of a polypropylene resin, or a film of an acrylic resin may be used. A polyethylene terephthalate resin film or the like is used. When a polyethylene terephthalate resin film is used as the transparent protective layer 4, it can be used for car rides, etc., in accordance with the thinning of the liquid crystal panel to be used, and the durability is improved. It is better for its use.

The polyethylene terephthalate refers to a resin composed of ethylene terephthalate of 80 mol% or more of the repeating unit. Other copolymerization components include, for example, isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis(4-carboxyphenyl)ethane, and hexane. Dicarboxylic acid components such as acid, sebacic acid, sodium isophthalate-5-sulfonate, 1,4-dicarboxycyclohexane; propylene glycol, butanediol, neopentyl glycol, diethylene glycol A diol component such as an alcohol, cyclohexanediol, an ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, or tetramethylene glycol. These dicarboxylic acid components or diol components can be used in combination of 2 or more types as needed. Further, a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p-hydroxyethoxybenzoic acid may be used in combination. Such other copolymerization components may also contain a compound containing a small amount of a guanamine bond, a urethane bond, an ether bond, a carbonate bond or the like.

The method for producing ethylene terephthalate can be a so-called direct polymerization method in which terephthalic acid and ethylene glycol are directly reacted, and so-called transesterification in which transesterification of dimethyl terephthalate with ethylene glycol is carried out. Various methods known in the art, such as reaction methods. Further, a known additive may be contained as needed. It may contain, for example, a lubricant, an antiblocking agent, a thermal stabilizer, an antioxidant, an antistatic agent, a light stabilizer, an impact modifier, and the like. However, since transparency is required in optical applications, it is preferred that the amount of the additive be limited to a minimum.

When the polyethylene terephthalate film is used as the transparent protective layer 4, it is preferred to carry out stretching such as uniaxial stretching or biaxial stretching.

The raw material resin is formed into a film shape, and an extended polyethylene terephthalate film can be produced by performing an elongation treatment. The extension may be performed according to any of the following methods: a uniaxial extension extending in the MD direction (flow direction) or the TD direction (direction orthogonal to the flow direction), and a biaxial extension extending bidirectionally in the MD direction and the TD direction. And extending obliquely in the direction of neither the MD direction nor the TD direction. By performing such an extension operation, a polyethylene terephthalate film having high mechanical strength can be obtained. The thus stretched polyethylene terephthalate film, especially the biaxially stretched polyethylene terephthalate film, is preferred in terms of productivity or strength, and in the use of the present invention In the liquid crystal display device of the liquid crystal panel, it is preferable that the interference fringe is hard to be seen.

The method for producing the stretched polyethylene terephthalate film is arbitrary, and for example, if it is a uniaxial stretching, for example, a non-oriented film in which the raw material resin is melted and extruded into a sheet shape is used, in the glass. A method in which heat setting treatment is performed after lateral stretching (later extending in the TD direction) by a tenter at a temperature higher than the transfer temperature. The stretching temperature is preferably from 80 to 130 ° C, more preferably from 90 to 120 ° C, and the stretching ratio is preferably from 2.5 to 6 times, more preferably from 3 to 5.5 times. When the stretching ratio is low, the polyethylene terephthalate film tends not to exhibit sufficient transparency. In the case of biaxial stretching, for example, the non-oriented film extruded into a sheet shape is extended in the longitudinal direction (MD) at a temperature higher than the glass transition temperature, and then extended in the transverse direction (TD). Method; or a method of extending simultaneously in the vertical and horizontal directions.

From the viewpoint of reducing the deformation of the orientation main axis in the polyethylene terephthalate film, it is preferred to carry out the relaxation treatment after the stretching. For example, when the uniaxially stretched film is produced by the above-described lateral stretching, for example, a method of performing relaxation treatment after lateral stretching and before performing heat setting treatment may be mentioned. The temperature of the relaxation treatment is from 90 to 200 ° C, preferably from 120 to 180 ° C. Although the amount of slack varies depending on the stretching conditions, it is preferable to set the amount of slack and the temperature so that the heat shrinkage rate at 150 ° C of the film after the relaxation treatment is 2% or less.

The temperature of the heat setting treatment is generally from 180 to 250 ° C, preferably from 200 to 245 ° C. The heat setting treatment is first performed at a predetermined temperature in a predetermined length, and further preferably treated so that the ratio of the relaxation in the width direction of the film is 1 to 10% (more preferably 2 to 5%). The polyethylene terephthalate film whose deformation of the oriented main shaft obtained by the method is reduced can be made such that the maximum deformation of the orientation main axis becomes 10 degrees or less, and the maximum deformation of the orientation main axis is 8 degrees. Hereinafter, it is more preferably 5 degrees or less. When a polyethylene terephthalate film having a maximum deformation of the oriented main axis of more than 10 degrees is used, when the polarizing plate obtained therefrom is used for a liquid crystal panel of a liquid crystal display device, coloring defects tend to become large. The maximum value of the deformation of the orientation main axis of the above-mentioned polyethylene terephthalate film can be measured, for example, by using a retardation film inspection apparatus "RETS system" (manufactured by Otsuka Electronics Co., Ltd.).

When a polyethylene terephthalate film is used as the transparent protective layer 4, the thickness thereof is preferably in the range of 20 to 50 μm. When a polyethylene terephthalate film having a thickness of less than 20 μm is used, the handleability of the film tends to be difficult, and if a polyethylene terephthalate film having a thickness of more than 50 μm is used, the advantage of thinning is obtained. Fewer.

The polyethylene terephthalate film can be used to impart haze in the range of 0.1 to 40%, preferably a haze value of 0.1 to 10%, more preferably 0.1 to 5%. The haze value is defined as a ratio of the diffusion transmittance to the total light transmittance as defined in JIS K 7136, and can be measured using a commercially available haze meter.

For the method of imparting haze to the polyethylene terephthalate film, for example, a method of mixing inorganic fine particles or organic fine particles in polyethylene terephthalate as a raw material resin; coating the surface of the above film A method in which a cloth is a coating liquid obtained by mixing inorganic fine particles or organic fine particles with a resin binder. Here, the inorganic fine particles may, for example, be cerium oxide, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-cerium oxide composite oxide, kaolin, talc, mica. Calcium carbonate, calcium phosphate, etc. are representative. Further, examples of the organic fine particles include heat-resistant resin particles such as crosslinked polyacrylic acid particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, polysilicon oxide resin particles, and polyamidene particles.

The polyethylene terephthalate film preferably has an in-plane retardation value R ₀ of 1,000 nm or more, more preferably 3,000 nm or more. When a polyethylene terephthalate film having an in-plane retardation value R _{0 of} less than 1000 nm is used, there is a clear tendency for coloring from the front side. The upper limit of the in-plane retardation value R ₀ of the polyethylene terephthalate film is sufficient to be about 10,000 nm.

The polyethylene terephthalate film having the above characteristics is excellent in terms of mechanical properties, solvent resistance, scratch resistance, cost, and the like.

In the polyethylene terephthalate film, an easy adhesion layer can also be imparted. The easy-to-attach layer refers to a layer provided to improve the adhesion between the polarizer and polyethylene terephthalate. The method for forming the polyethylene terephthalate film to which the easy-adhesion layer is provided is not particularly limited, but for example, a method of forming an easy-adhesion layer after the end of the entire stretching step can be employed; In the step of extending the ethylene dicarboxylate, that is, a method of forming an easy-to-adhere layer between the longitudinal stretching step and the lateral stretching step; a method of forming an easy-to-adhere layer or the like immediately before or after the polarizer is formed. In the case of producing a biaxially stretched film, from the viewpoint of productivity, a method of forming an easy-adhesion layer after longitudinally stretching polyethylene terephthalate, followed by lateral stretching is preferably employed. The easy-adhesion layer can be applied to both sides of the polyethylene terephthalate film, or can be bonded to one side of the polarizer composed of a polyvinyl alcohol-based resin via an adhesive.

The component constituting the easy-adhesion layer may be, for example, a polyester resin, a urethane resin, an acrylic resin, or the like having a polar group and a relatively low molecular weight and a low glass transition temperature. . Further, a crosslinking agent, an organic or inorganic filler, a surfactant, a lubricant, or the like may be contained as needed.

A surface treatment such as anti-glare treatment, hard coating treatment, and antistatic treatment may be applied to the surface of the transparent protective layer 4 opposite to the surface to which the polarizer 3 is adhered. Further, a coating layer composed of a liquid crystal compound or a high molecular weight compound thereof may be formed. Further, even if a polyethylene naphthalate film is used in place of the polyethylene terephthalate film, about the same effect can be obtained.

Such a polyethylene terephthalate film can be easily obtained as a commercial product, and the product name can be, for example, Diafoil (manufactured by Mitsubishi Plastics Co., Ltd.), Hostaphan (manufactured by Mitsubishi Plastics Co., Ltd.), and Fusion (Mitsubishi Resin Co., Ltd.). , Teijin Tetoron film (made by Teijin Dupont Film Co., Ltd.), Melinex (made by Teijin Dupont Film Co., Ltd.), Mylar (made by Teijin Dupont Film Co., Ltd.), Teflex (made by Teijin Dupont Film Co., Ltd.), Toyo Sewing Film (Toyo) Co., Ltd.), Toyobo Espet Film (manufactured by Toyobo Co., Ltd.), Cosmoshine (manufactured by Toyobo Co., Ltd.), Crisper (manufactured by Toyobo Co., Ltd.), Lumirror (manufactured by Toray Film Processing Co., Ltd.), Emblon (Unitika Co., Ltd.) System, Embed (made by Unitika Co., Ltd.), Skyroll (made by SKC), Kofil (made by Kogyo Co., Ltd.), Ruitong Polyester Film (made by Ruitong Co., Ltd.), Taige Polyester Film (Futamura Chemical Co., Ltd.) System) and so on.

In the present invention, it is also preferred to use a non-extended cyclic olefin resin film for the transparent protective layer 4. The cyclic olefin resin film is generally referred to as an amorphous polyolefin resin, an alicyclic polyolefin resin, a norbornene resin, or the like. In the present specification, the system 1 is a term "cyclic olefin resin".

When a cyclic olefin-based resin film is used as the transparent protective layer 4, the thickness of the liquid crystal panel can be reduced. This liquid crystal panel can be suitably used for applications such as vehicle riding due to improvement in durability. When a cyclic olefin resin film is used as the transparent protective layer 4, the thickness thereof is preferably in the range of 15 to 25 μm, and when the thickness is less than 15 μm, the handleability of the film may become difficult. Moreover, by making the thickness 25 μm or less, it contributes to thinning.

The transparent protective layer 4 composed of a cyclic olefin resin is excellent in transparency and small in orientation, that is, a sheet having a small phase difference. Specifically, the transparency is a full haze value measured according to JIS K 7136 of 1% or less, preferably 0.5% or less. The in-plane retardation value is generally 5 nm or less, preferably 3 nm or less. The phase difference in the thickness direction is generally 10 nm or less, preferably 5 nm or less.

The cyclic olefin-based resin may, for example, be a ring opening metathesis polymerization using norbornene or a derivative thereof as a monomer, followed by hydrogenation; a tetracyclododecene (alias: dimethanooctahydronaphthalene) or a derivative thereof as a monomer, a ring-opening metathesis polymerization, followed by hydrogenation of a resin; using two or more kinds of norbornene, tetracyclododecan a cyclic olefin monomer composed of an alkene, such a derivative or the like, and similarly subjected to ring-opening metathesis copolymerization, followed by hydrogenation to obtain a copolymerized resin; and having a cyclic olefin monomer as described above and a vinyl group A resin or the like obtained by copolymerization of an aliphatic or aromatic compound by addition polymerization.

A commercially available product can be easily obtained by the above-mentioned cyclic olefin resin. For each product name, for example, Topas (manufactured by Topas Advanced Polymers GmbH), Arton (manufactured by JSR AG), Zeonor (manufactured by Japan Zeon Co., Ltd.), and Zeonex (made by Japan Zeon Co., Ltd.), Apel (made by Mitsui Chemicals Co., Ltd.), etc.

The cyclic olefin resin film can be obtained by molding the above cyclic olefin resin into a film shape. The method of forming the resin into a film shape is not particularly limited, and a known molding method such as a hot melt molding method or a solution vertical flow method may be employed, but the viewpoint of reducing volatile components remaining in the film is not limited. In view of the above, it is preferred to use a hot melt forming method in which a melt extrusion molding method is preferred.

The conditions of the melt extrusion molding are appropriately selected depending on the properties of the resin to be used or the production apparatus, and are not particularly limited. For example, it is preferred to have a cylinder temperature of about 100 to 600 ° C, more preferably 150 to 350 ° C. .

When a cyclic olefin-based resin film is produced, an additive can be added to the extent that the object of the present invention is not inhibited. The additive which can be formulated may, for example, be a plasticizer or a deterioration inhibitor. The plasticizer is added to improve the mechanical properties of the film or to increase the drying speed. Specific examples of the plasticizer are phosphates or carboxylates.

Examples of the phosphate ester to be a plasticizer include triphenyl phosphate and tricresyl phosphate. Further, examples of the carboxylic acid ester to be a plasticizer include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and phthalic acid. Phthalate esters such as diphenyl ester; citrate esters such as O-ethyl decyl triethyl citrate and O-ethyl decyl tributyl citrate; butyl oleate and ricinoleate And higher fatty acid esters such as dibutyl sebacate; trimellitic acid esters.

Examples of the deterioration inhibitor include an antioxidant, a peroxide decomposer, a radical polymerization inhibitor, a metal inerting agent, an acid scavenger, and an amine. The specific deterioration inhibitors are disclosed in Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. Those recorded in the Gazette.

The amount of the additives is usually 20% by weight or less, preferably 10% by weight or less, and more preferably 5% by weight or less based on the cyclic olefin resin.

In the cyclic olefin resin film, a film forming condition derived from a cyclic olefin resin raw material can be appropriately selected by a known selection of a known film forming apparatus, and the thickness, haze value, and phase can be displayed. Manufactured by the difference method.

[Relativity film]

A biaxial retardation film 5 made of a cyclic olefin resin can be provided on the other surface of the polarizer 3. The retardation film 5 can be obtained by stretching a cyclic olefin resin film. The olefin-based resin film is, for example, a chain olefin monomer such as ethylene or propylene, or a norbornene or tetracyclododecene (alias: dimethyl bridge octahydrogen) similar to those previously described for the transparent protective layer. A film composed of a resin obtained by polymerization of a cyclic olefin monomer such as naphthalene) and a derivative thereof. In the present invention, the user is preferably a cyclic olefin resin. When a cyclic olefin-based resin is used, a film obtained by stretching a mixture of a cyclic olefin polymer having a positive wavelength dispersion property and a cyclic olefin polymer having a reverse wavelength dispersion property is used, and thus the film can be easily formed. The adjustment of the wavelength dispersion characteristics is performed, and a biaxial retardation film can be easily obtained.

When a cyclic olefin resin is used as the retardation film 5, the same resin as that previously described for the transparent protective layer can be used. The thickness of the cyclic olefin-based resin film which is a raw material of the retardation film is appropriately determined depending on the purpose of use of the obtained stretched film, and the like, and is not particularly limited, but is obtained, for example, from a stable stretching treatment. From the viewpoint of the homogeneously stretched film, it is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 30 μm or more. Further, the thickness of the cyclic olefin resin film is preferably 300 μm or less, more preferably 200 μm or less, particularly preferably 100 μm or less, and most preferably 80 μm or less.

The unstretched film produced by using the olefin-based resin is stretched in the longitudinal direction (MD) and the width direction (TD) successively or simultaneously, whereby a biaxial retardation film can be formed. In this case, the extending main axis, that is, the direction in which the stretching ratio becomes large, may be in the longitudinal direction or in the wide direction. However, if the extending main axis is in the wide direction, a long and wide retardation film can be obtained.

The temperature at which the unstretched film is extended is preferably in the range of Tg-30 ° C to Tg + 60 ° C, more preferably Tg - 10 ° C to Tg, when the glass transition temperature of the cyclic olefin resin is Tg. +50 ° C range. Further, the stretching ratio is selected, for example, from 1.01 to 30 times, preferably from 1.01 to 10 times, more preferably from 1.01 to 5 times, in the longitudinal direction and the width direction, respectively. The stretching ratio in the width direction may be larger than the stretching ratio in the direction orthogonal thereto.

In the case of the olefin-based resin film, a phase difference film can be easily obtained as a commercial product, and the product name of the cyclic olefin resin film is, for example, a Zeonor film (manufactured by Zeon Co., Ltd.). , Arton film (manufactured by JSR Co., Ltd.), Escena retardation film (made by Sekisui Chemical Co., Ltd.), and the like.

The phase difference value of the retardation film 5 will be described. The refractive index in the slow axis direction of the film is n _x , the in-plane fast axis direction (the direction orthogonal to the slow axis in the plane) is n _y , and the refractive index in the thickness direction is n _z . Further, when the thickness is d, the in-plane phase difference value R ₀ and the thickness difference phase phase R _th and the η _z coefficient are defined by the following formulas (I), (II), and (III), respectively.

R ₀ =(n _x -n _y )×d (I)

R _th =[(n _x +n _y )/2-n _z ]×d (II)

N _z =(n _x -n _z )/(n _x -n _y ) (III)

And, from the other formula (I), (II) and (III), the value of N _z retardation coefficient R ₀ and the plane retardation and the thickness direction R _th of the value of the relationship may be the following formula (IV) FIG.

N _z =R _th /R ₀ +0.5(IV)

In the present invention, a biaxial property is used as the retardation film 5 from the viewpoint of compensating for the phase difference of the TN mode liquid crystal cell, particularly, the viewing angle in the lateral direction of the screen. Here, the biaxial property means that the refractive indices n _x , n _{y ,} and n _{z in} the triaxial directions defined above satisfy the relationship of n _x >n _y >n _z . The in-plane retardation value R ₀ of the retardation film 5 is 40 to 150 nm, preferably 60 to 130 nm. Further, the phase difference _{Rth in} the thickness direction of the retardation film 5 is 50 to 250 nm, preferably 100 to 200 nm. Further, the N _z coefficient exceeds 1 and is 7 or less, and more preferably 1.5 to 4.

The retardation film composed of the olefin resin generally has a thickness of 10 to 100 μm, preferably 20 to 80 μm. When the thickness is less than 10 μm, the bio-operability is lowered.

Further, the retardation film preferably has a residual volatile component content of 1000 ppm by weight or less, more preferably 500 ppm by weight or less, and most preferably 200 ppm by weight or less. When the amount of the residual volatile component exceeds 1000 ppm by weight, the volatile component is released to the outside during use, and dimensional change occurs in the retardation film to cause internal stress. Therefore, when a composite polarizing plate is produced from a retardation film in which a plurality of such residual volatile components remain, and is used in a liquid crystal display device, the black display portion is locally lightened (it seems to be whitened) and the like is uneven. . When a retardation film having a volatile component content in the above range is used, even if a liquid crystal display device is used for a long period of time, display unevenness does not occur, and the stability of optical characteristics is excellent.

The retardation film preferably has a saturated water absorption of 0.01% by weight or less. When the saturated water absorption ratio exceeds 0.01% by weight, the retardation film is dimensionally changed depending on the use environment, and internal stress may occur. Therefore, when a composite polarizing plate is produced from such a retardation film having a high saturated water supply rate and used in a liquid crystal display device, the display portion of the black display portion may be partially faded (it seems to be whitened). When a retardation film having a saturated water absorption ratio in the above range is used, even if a liquid crystal display device is used for a long period of time, display unevenness does not occur, and the stability of optical characteristics is excellent.

[Polarizer and transparent protective layer and retardation film]

When the retardation film 5 composed of the olefin-based resin film is attached to the polarizer 3, the axial relationship between the two may be selected as the optimum viewing angle characteristics or color change characteristics in the liquid crystal display device. In the panel use for TN, the slow axis of the retardation film 5 and the absorption axis of the polarizer 3 are often arranged in a slightly parallel or slightly orthogonal relationship. Here, "slightly" or slightly orthogonal "slightly" means that the deviation is allowed to be about ±10° centered on the relationship (in this case, parallel or orthogonal). The deviation of this angle is preferably within ±5°, and more preferably within ±2°.

In the application of the TN mode liquid crystal panel, if the rubbing axis of the polarizing plate overlaps with the rubbing direction of the liquid crystal cell, it is defined as the E mode, and if the polarizing plate penetrates the axis and the rubbing direction of the liquid crystal cell is In the vertical case, it is defined as O mode. In the present invention, in order to make the viewing angle characteristic excellent, the E-mode in which the rubbing direction of the composite polarizing plate 10 and the liquid crystal cell 50 overlap, the rubbing direction of the composite polarizing plate 10 and the rubbing direction of the liquid crystal cell 50 are positive. The O mode can be used. In order to obtain more excellent viewing angle characteristics, the O mode should be used.

The retardation film 5 and the polarizer 3 which are formed of the olefin resin and the polarizer 3, which are followed by the transparent protective layer 4 and the polarizer 3, may be, for example, an epoxy resin, a urethane resin or a cyano group. Any of these may be used as an adhesive for an acrylate resin or an acrylamide resin, and a good adhesive force can be obtained. From the viewpoint of thinning the adhesive layer, a preferred adhesive is, for example, a solventless type of adhesive, and specifically, a monomer or an oligomer can be exemplified by heating or irradiation with an active energy ray. The reaction hardening is carried out to form an adhesive layer.

Describe the solvent-free adhesive. The solventless type adhesive agent does not contain a significant amount of a solvent, and generally contains a curable compound which is polymerized by heating or irradiation with an active energy ray, and a polymerization initiator. From the viewpoint of reactivity, it is preferred to carry out curing by cationic polymerization, and it is particularly preferred to use an epoxy-based adhesive.

Therefore, for example, a transparent protective layer 4 and a polarizer 3, and a retardation film 5 made of an olefin resin and a polarizer 3 are each a solvent-free epoxy-based adhesive. Shape. The adhesive is preferably one which undergoes cationic polymerization for curing by heating or irradiation of an active energy ray. In particular, from the viewpoint of weather resistance, refractive index, and the like, an epoxy compound having no aromatic ring in the molecule is suitably used as a curable compound. An adhesive agent using an epoxy compound which does not contain an aromatic ring in the molecule is described, for example, in JP-A-2004-245925. Examples of the epoxy compound which does not contain an aromatic ring include a hydrogenated product of an aromatic epoxy compound, an alicyclic epoxy compound, and an aliphatic epoxy compound. The curable epoxy compound used in the subsequent agent generally has two or more epoxy groups in the molecule.

A hydride of an aromatic epoxy compound is obtained by selectively hydrogenating an aromatic ring by an aromatic polyhydroxy compound which is a raw material of an aromatic epoxy compound in the presence of a catalyst under pressure. A hydroxy compound obtained by subjecting the nuclear hydrogenated polyhydroxy compound to glycidyl etherification. Examples of the aromatic polyhydroxy compound which is a raw material of the aromatic epoxy compound include bisphenols such as bisphenol A, bisphenol F, and bisphenol S; phenol novolac resin and cresol novolac resin; And a novolac type resin such as hydroxybenzaldehyde phenol novolak resin; a polyfunctional compound such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, or polyvinylphenol. The glycidyl etherification can be carried out by reacting epichlorohydrin with a hydride of such an aromatic polyhydroxy compound. Preferred among the hydride of the aromatic epoxy compound is, for example, a glycidyl ether of hydrogenated bisphenol A.

The alicyclic epoxy compound is a compound having at least one (-O-) directly bonded to an alicyclic ring in the molecule, as shown in the following formula, wherein m represents an integer of 2 to 5.

A group in which one or a plurality of hydrogen atoms in the (CH ₂ ) _m in the formula are removed and bonded to another chemical structure may 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, a compound having an epoxycyclopentane ring (m=3 in the above formula) or an epoxycyclohexane ring (m=4 in the above formula) is preferably used. Specific examples of the alicyclic epoxy compound include the following.

‧3,4-epoxycyclohexanecarboxylic acid 3,4-epoxycyclohexylmethyl ester

‧3,4-epoxy-6-methylcyclohexanecarboxylic acid 3,4-epoxy-6-methylcyclohexylmethyl ester

‧Extended ethyl bis(3,4-epoxycyclohexane carboxylate)

‧Bis(3,4-epoxycyclohexylmethyl) adipate

‧Bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate

‧ Diethylene glycol bis(3,4-epoxycyclohexyl methyl ether)

‧Ethylene glycol bis(3,4-epoxycyclohexyl methyl ether)

‧2,3,14,15-Diepoxy-7,11,18,21-tetraoxaspiro-[5.2.2.5.2.2]hexadecane (may also be named 3,4-epoxy Hexacyclohexane-2',6'-di Alkane-3", 5"-two Alkyl-3''', 4'''-epoxycyclohexane compound)

‧4-(3,4-Epoxycyclohexyl)-2,6-dioxa-8,9-epoxyspiro[5.5]undecane

‧4-vinylcyclohexene dioxide

‧1,2:8,9-diepoxylimene

‧Bis-2,3-epoxycyclopentyl ether

‧ dicyclopentadiene dioxide

The alicyclic epoxy compound may be a polyglycidyl ether of an aliphatic polyol or an alkylene oxide adduct thereof. For example, diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerol, triglycidyl group of trimethylolpropane Ether, diglycidyl ether of polyethylene glycol, diglycidyl ether of polypropylene glycol, addition of one or more alkylene oxides to an aliphatic polyol such as ethylene glycol or polypropylene glycol or glycerin Polyglycidyl ether of a polyether polyol obtained by oxyethane or propylene oxide.

The epoxy compounds exemplified herein may be used singly or in combination of plural kinds.

The epoxy equivalent of the epoxy compound used in the solventless type of the adhesive is generally from 30 to 3,000 g/equivalent, preferably from 50 to 1,500 g/equivalent. When the epoxy equivalent is less than 30 g/eq, the flexibility of the cured protective film may be lowered or the strength may be lowered. Further, when the epoxy equivalent exceeds 3,000 g/eq, the compatibility with other components may be lowered.

In order to harden the epoxy compound by cationic polymerization, a cationic polymerization initiator is formulated. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation or heating of an active energy ray such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates polymerization of an epoxy group. From the standpoint of workability, any type of cationic polymerization initiator is preferred because it imparts potential.

Hereinafter, the photocationic polymerization initiator will be described. When a photocationic polymerization initiator is used, hardening at normal temperature is made possible, and the necessity of deformation due to heat resistance or expansion of the polarizer is reduced, and the retardation film and the polarizer can be satisfactorily advanced. . Further, since the photocationic polymerization initiator acts as a photocatalyst by light, it is excellent in storage stability and workability even when it is mixed in an epoxy compound. A compound of a cationic species or a Lewis acid is produced by irradiation with an active energy ray, and examples thereof include an diazonium salt; an iodonium salt or a sulfonium salt; Onium salt; iron-propadiene complex and the like. Among them, the aromatic sulfonium salt is preferably used because it exhibits ultraviolet absorbing properties in a wavelength region around 300 nm and can provide a cured product having excellent curability and good mechanical strength or adhesion strength.

A commercially available product can be easily obtained as a photocationic polymerization initiator, and the product name can be, for example, Kayarad 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 (made by ADEKA), ADEKA Optomer SP-170 (made by ADEKA), CI-5102 (made by Japan Soda Co., Ltd.), CIT- 1370 (Japan Soda (share) system), CIT-1682 (Japan Soda (share) system), CIP-1866S (Japan Soda (share) system), CIP-2048S (Japan Soda (share) system), CIP-2064S ( Japan's Caoda (share) system), DPI-101 (green chemical (share) system), DPI-102L (green chemical (share) system), DPI-103 (green chemical (share) system), DPI-105 (green chemistry) (share) system), MPI-103 (green chemical (share) system), MPI-105 (green chemical (share) system), BBI-101 (green chemical (share) system), BBI-102 (green chemical (share) )), BBI-103 (green chemical (share) system), BBI-105 (green chemical (share) system), TPS-101 (green chemical (share) system), TPS-102 (green chemical (share) system ), TPS-103 (Green Chemical Co., Ltd.), TPS-105 (Green Chemical Co., Ltd.), MDS-103 (Green Chemical Co., Ltd.), MDS-105 (Green Chemical Co., Ltd.), DTS-102 (Green Chemical Co., Ltd.), DTS-103 (Green Chemical Co., Ltd.) ), PI-2074 (made by Rhodia Corporation), etc.

The compounding amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of the epoxy compound.

Further, a photosensitizer can be used in combination as needed. By using a photosensitizer, the reactivity can be improved and the mechanical strength or strength of the cured product can be increased. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfide compound, a redox compound, an azo and a diazo compound, a halogen compound, and a photoreducible dye. In the case where the photo-sensitizing epoxy resin composition is used in an amount of 100 parts by weight, the amount is usually about 0.1 to 20 parts by weight.

Next, the thermal cationic polymerization initiator will be described. The compound which generates a cationic species or a Lewis acid by heating may, for example, be a benzyl sulfonium salt, a thiophenium salt, a thiolanium salt, a benzylammonium salt or a pyridinium salt. A hydrazinium salt, a carboxylic acid ester, a sulfonate, an amine imine or the like. For the thermal cationic polymerization initiator, a commercially available product can be easily obtained. For example, the product name may be, for example, ADEKA Opton CP77 (manufactured by ADEKA), ADEKA Opton CP66 (made by ADEKA), CI- 2639 (Japan Soda (share) system), CI-2624 (Japan Soda (share) system), San-aid SI-60L (Sanshin Chemical Industry Co., Ltd.), San-aid SI-80L (Sanshin Chemical Industry) (share) system, San-aid SI-100L (Sanshin Chemical Industry Co., Ltd.), etc.

Photocationic polymerization and thermal cationic polymerization can also be used in combination. The epoxy-based adhesive may further contain a compound which promotes cationic polymerization such as an oxetane or a polyhydric alcohol.

When a polarizer, a transparent protective layer, and a polarizer and a retardation film are attached by using an epoxy-based hardening type adhesive as described above, generally, a method of coating at least one of the succeeding faces may be employed. This adhesive is a method in which the second film is bonded and the adhesive is cured by the adhesive coating layer. It is also possible to simultaneously bond the transparent protective layer and the retardation film from both sides of the polarizer while hardening at the same time. When the adhesive is applied to the adhesive surface, various coating methods including, for example, a doctor blade, a wire bar, a die coater, a Comma coater, a gravure coater, and the like can be employed. Moreover, since each coating method has an optimum viscosity range, it is also possible to adjust the viscosity using a small amount of solvent. The solvent to be used herein may be any one which does not lower the optical performance of the polarizer and dissolves the epoxy-based adhesive well, and examples thereof include hydrocarbons represented by toluene and esters represented by ethyl acetate. Organic solvents. When a solventless epoxy-based adhesive is used, the thickness of the adhesive layer is generally 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less, and usually 1 μm or more.

After bonding the transparent protective layer and/or the retardation film to the polarizer via the uncured adhesive layer, the epoxy adhesive layer is cured by irradiating the active energy ray or heating, and the transparent protective layer is cured. And/or the retardation film is fixed to the polarizer. When the transparent protective layer is subsequently applied to the polarizer or the retardation film is subsequently applied, the operations are repeated. When it is hardened by irradiation with an active energy ray, 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 or the irradiation amount of the active energy ray (especially ultraviolet ray) is a method in which the polymerization initiator is sufficiently activated and does not adversely affect the cured adhesive layer or the polarizer, the retardation film, and the transparent protective layer. Just choose it. Further, when it is hardened by heating, it can be heated by a generally known method, and the temperature or time is also required to sufficiently activate the polymerization initiator, and not to cure the adhesive layer or polarizer, phase. The poor film and the transparent protective layer may be appropriately selected in a manner that adversely affects the manner.

Further, as another preferred adhesive which can be used in the present invention, for example, a water-based adhesive, that is, a binder component is dissolved in water or dispersed in water. If a water based adhesive is used, the thickness of the adhesive layer can be further reduced. The water-based adhesive agent may, for example, be a component containing, for example, a water-soluble crosslinkable epoxy resin or a water-soluble urethane-based resin.

The water-soluble crosslinkable epoxy resin may, for example, be a reaction with a polyalkyleneamine such as diethylene triamine or triethylenetetramine or a dicarboxylic acid such as adipic acid. The obtained polyamidamine polyamine is a polyamine epoxy resin obtained by reacting epichlorohydrin. Commercially available products of such polyamine epoxy resins are Sumirez Resin 650 (sold by Sumitomo Chemtex Co., Ltd.), Sumirez Resin 675 (sold by Sumitomo Chemtex Co., Ltd.), and the like.

When a water-soluble crosslinkable epoxy resin is used as the adhesive component, in order to further improve coatability and adhesion, it is preferable to mix another water-soluble resin such as a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin may be a carboxy-modified polyvinyl alcohol, an ethyl acetylated-modified polyvinyl alcohol or a hydroxymethyl-modified polyvinyl alcohol, in addition to a partially saponified polyvinyl alcohol or a fully saponified polyvinyl alcohol. A modified polyvinyl alcohol-based resin such as an amine-modified polyvinyl alcohol. Among them, a saponified product of a copolymer of vinyl acetate and an unsaturated carboxylic acid or a salt thereof, that is, a carboxyl group-modified polyvinyl alcohol, is preferably used. Here, the "carboxy group" herein includes the concept of -COOH and its salt.

Preferred carboxy-modified polyvinyl alcohols which are commercially available are, for example, Kuraray Poval KL-506 (sold by Kuraray), Kuraray Poval KL-318 (sold by Kuraray), Kuraray Poval KL-118 ( Sold by Kuraray, Gosenal T-330 (sold by Japan Synthetic Chemical Industry Co., Ltd.), Gosenal T-350 (sold by Japan Synthetic Chemical Industry Co., Ltd.), DR-0415 (by Electrochemical Industry) )), AF-17 (sold by Vam Poval (share) in Japan), AP-17 (sold by Vam Poval (share) in Japan), etc.

An adhesive containing a water-soluble crosslinkable epoxy resin can be prepared by dissolving the above-mentioned epoxy resin and other water-soluble resin such as a polyvinyl alcohol-based resin added thereto as water as an adhesive solution. . At this time, the water-soluble crosslinkable epoxy resin is preferably in a concentration range of about 0.2 to 2 parts by weight based on 100 parts by weight of water. Moreover, when the polyvinyl alcohol-based resin is blended, the amount thereof is preferably from about 1 to 10 parts by weight, more preferably from about 1 to about 5 parts by weight, per 100 parts by weight of water.

Further, when an aqueous binder containing an urethane-based resin is used, an example of an appropriate urethane resin may, for example, be an ionomer type urethane resin. In particular, a polyester-based ionic polymer type urethane resin. Here, the ionic polymer type refers to a small amount of an ionic component (hydrophilic component) introduced into a urethane resin constituting a skeleton. Further, the polyester-based ionic polymer type urethane resin refers to a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced therein. Since such an ionic polymer type urethane resin is directly emulsified in water to form an emulsion without using an emulsifier, it is suitable as an aqueous binder. Commercial products of the polyester-based ionic polymer type urethane resin include, for example, Hydran AP-20 (sold by DIC), Hydran APX-101H (sold by DIC), and the like. Both can be obtained in the form of an emulsion.

When an ionic polymer type urethane resin is used as an adhesive component, it is preferable to further mix a crosslinking agent, such as an isocyanate type. The isocyanate crosslinking agent is a compound having at least two isocyanato groups (-NCO) in the molecule, and examples thereof are: 2,4-tolyl diisocyanate, phenylphenyl diisocyanate, 4,4'- In addition to polyisocyanate monomers such as diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, and isophorone diisocyanate, for example, such a plurality of molecules are added to a plurality of molecules such as trimethylolpropane. An alcohol-derived adduct, a diisocyanate 3 molecule, a mono-isocyanurate ring, a trifunctional isocyanurate ring, a difunctional isocyanurate ring, a di-isocyanurate, a diisocyanate, and a diisocyanate The base portion is subjected to a polyisocyanate modified body such as a biuret formed by hydration or decarbonation. Commercially available isocyanate-based crosslinking agents which can be suitably used include, for example, Hydran assister C-1 (sold by DIC).

When a water-based adhesive containing an ionic polymer type urethane resin is used, the concentration of the urethane resin is preferably from 10 to 70% by weight from the viewpoint of viscosity and adhesion. It is preferred to be dissolved or dispersed in water so as to be 20% by weight or more and 50% by weight or less. In the case of the isocyanate-based crosslinking agent, the amount of the isocyanate-based crosslinking agent is suitably selected from about 5 to 100 parts by weight based on 100 parts by weight of the urethane resin.

When the water-based adhesive is used, the polarizer and the transparent protective layer are followed by the polarizer and the retardation film, and the adhesive can be applied to at least one of the bonding faces of the substrate, and then Fit both together. More specifically, a method in which a water-based adhesive is applied to, for example, a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater or the like on at least one of the film faces of the film may be employed. After the method is uniformly applied, the other film is superposed on the coated surface, and the film is bonded by a roll or the like, and dried. The drying system can be carried out at a temperature of, for example, about 60 to 100 °C. In order to further improve the adhesion, it is preferable to culture for about 1 to 10 days at a temperature slightly higher than room temperature (for example, a temperature of about 30 to 50 ° C) after drying.

In the same manner as the solvent-free epoxy-based adhesive, the water-based adhesive can be preferably used in a combination of a transparent protective layer and a polarizer, or a biaxial retardation film composed of an olefin-based resin film. The bonding with the polarizer or the fit of the two. The film laminated on both sides of the polarizer may be the same adhesive used in the subsequent step, or a different adhesive may be used, but in order to achieve the simplification of the manufacturing steps and the reduction of the constituent members of the polarizing plate, the same use should be used. Adhesive.

[Adhesive layer]

In the composite polarizing plate of the present invention, the adhesive layer 6 is laminated on the outer side of the surface on which the retardation film is disposed. This adhesive layer is used for bonding to TN mode liquid crystal cells.

The adhesive constituting the adhesive layer 6 is preferably a storage elastic modulus of 0.15 to 10 MPa in 23 to 80 ° C in order to prevent the occurrence of light leakage. In the present specification, the phrase "the storage elastic modulus of 0.15 to 10 MPa in 23 to 80 ° C" means that the storage elastic modulus at any temperature in the range is a value of the above range. The storage elastic modulus generally decreases with increasing temperature. Therefore, as long as the storage elastic modulus at 23 ° C and 80 ° C is within the above range, the storage elastic modulus showing the above range can be seen in the temperature of this range. .

Here, the storage elastic modulus is a value obtained by a general dynamic viscoelasticity measurement. That is, it is based on a dynamic viscoelasticity measurement method in which a deformation or stress which vibrates with time is applied to a sample and the stress or deformation caused thereby is determined to determine the mechanical properties of the sample, specifically, When the generated stress (or deformation) is divided into two components that are in phase with the applied deformation (or stress) and two components with a phase offset of 90°, from the same phase as the applied deformation (or stress) The modulus of elasticity obtained by the composition. The storage elastic modulus can be measured using a commercially available viscoelasticity measuring device, for example, a dynamic viscoelasticity measuring device (DVA-220, manufactured by IT Measurement Control Co., Ltd.) shown in the examples below. In the dynamic viscoelasticity measuring apparatus, various known temperature control devices such as a circulating thermostat, an electric heater, and a Peltier device are suitably used for the temperature control of the sample. Further, for the sample, a deformation of 0.01 to 10% or a stress of 0.001 to 10 N is generally applied with a vibration of 0.01 to 10 Hz. Further, in general, the stress or deformation produced is determined by the linear region of its stress-variation. The storage elastic modulus defined by the present invention is measured by applying a deformation of 0.1% at a set temperature of 1 Hz.

The adhesive used in the general TN mode liquid crystal display device or the optical film to which it is applied has a storage elastic modulus of only about 0.1 MPa, and is intended for a wide TN mode liquid crystal panel having a contrast angle of view in the lateral direction. The adhesive which is generally used for storing the elastic modulus may be used. However, when the adhesive used in the present invention is intended to prevent the occurrence of light leakage, the storage elastic modulus is preferably a value as high as described above. By using an adhesive exhibiting such a high storage elastic modulus, that is, using a hard adhesive, it is possible to compensate for insufficient cohesive force when placed in a high temperature environment or repeatedly in a high temperature environment and a low temperature environment, and can be suppressed. The dimensional change accompanying the contraction of the polarizer that occurs at this time. By this action, the TN mode liquid crystal display device having the TN mode liquid crystal panel using the composite polarizing plate of the present invention can maintain good display quality. The storage elastic modulus is, for example, 5 MPa or less, or may be 2 MPa or less.

The adhesive constituting the adhesive layer used in the present invention may have various properties (transparency, durability, reworkability, etc.) required for the adhesive of the optical film and satisfy the aforementioned viscoelastic property, and its constituent components are not In particular, an acrylic pressure-sensitive adhesive containing an acrylic resin and a crosslinking agent, which has a (meth) acrylate as a main component and further contains a (meth) group having a small amount of functional groups, can be suitably used. The glass transition temperature (T _g ) obtained by radical polymerization of the acrylic monomer mixture of the acrylic monomer in the presence of a polymerization initiator is 0 ° C or lower.

Here, the (meth) acrylate type which is a main component of an acrylic resin can be represented by the following formula:

CH ₂ =C(R ₁ )COOR ₂

In the formula, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkyl group having 1 to 14 carbon atoms, or an aralkyl group, and a hydrogen atom constituting an alkyl group of R ₂ or a hydrogen atom constituting an aralkyl group may pass through carbon Alkoxy groups of 1 to 10 are substituted.

Further, the (meth)acrylic single system having a functional group contains a polar functional group such as a hydroxyl group, a carboxyl group, an amine group or an epoxy group in the molecule and an olefinic double bond (generally (meth)acrylonitrile group) By.

In addition, in this specification, "(meth)acrylic acid..." means "acrylic acid..." or "methacrylic acid...".

Specific examples of the (meth) acrylate which is a main component of the acrylic resin include butyl acrylate wherein R ₁ is H and R ₂ is n-butyl group, or R ₁ is H and R ₂ is 2-ethyl group. Hexyl 2-ethylhexyl acrylate or the like. Further, as a specific example of the (meth)acrylic monomer having a functional group, for example, a hydroxyl group may be, for example, 2-hydroxyethyl (meth)acrylate; and those having a carboxyl group may, for example, be acrylic acid. . Further, when the acrylic resin is produced, a monomer having a plurality of (meth)acryl fluorenyl groups in the molecule may be copolymerized in a small amount, and for example, 1,4-butanediol di(methyl) may be mentioned. Acrylate.

In the case of producing an acrylic resin, the (meth) acrylate and the (meth)acrylic single system having a functional group may be used singly or in combination of plural kinds. Further, a resin component of an adhesive may be used in which an acrylic resin belonging to a copolymer of a (meth) acrylate and a (meth)acrylic monomer having a functional group is used in combination, or In the acrylic resin belonging to the copolymer, another acrylic resin (for example, an acrylic resin composed of a (meth)acrylic monomer having no functional group as a single or a copolymer) is blended to form an acrylic resin composition. .

The crosslinking agent to be blended in the acrylic pressure-sensitive adhesive may be an isocyanate compound, an epoxy compound, a metal chelate compound, or an aziridine compound. With respect to the isocyanate-based compound, in addition to the compound itself having at least two isocyanato groups (-NCO) in the molecule, an adduct, a dimer thereof, a trimer thereof which can react with the polyol can be used. Use in other forms. Specific examples of the crosslinking agent include a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of tolyl diisocyanate, and the like. These are often used in the form of a solution dissolved in an organic solvent such as ethyl acetate.

The acrylic resin is dissolved in an organic solvent such as ethyl acetate, and a crosslinking agent is further added thereto to form an acrylic pressure-sensitive adhesive solution. Further, the acrylic adhesive solution may contain a decane coupling agent, a weathering stabilizer, a tackifier, a plasticizer, a softener, a pigment, an inorganic filler or an organic bead, as needed. Light diffusing fine particles and the like.

The acrylic pressure-sensitive adhesive solution obtained by such a method is usually applied onto a release film, and heated at 60 to 120 ° C for about 0.5 to 10 minutes to distill off the organic solvent to form an adhesive layer. After the adhesive layer is bonded to the retardation film constituting the composite polarizing plate, for example, it is aged for 5 to 20 days in an environment of a temperature of 23 ° C and a humidity of 65%, and the crosslinking agent may be sufficiently reacted.

Further, after the adhesive layer is obtained on the release film, the release film is further bonded, and a separate adhesive sheet layer which is not supported by the substrate such as the protective film can be obtained. At this time, after the release film is bonded, for example, it is aged for about 5 to 20 days at a temperature of 23 ° C and a humidity of 65% to sufficiently react the crosslinking agent. Such a separate sheet of the adhesive is used in the production of the composite polarizing plate at a certain period of time, and the release film on one side is peeled off and bonded to the retardation film.

The method of imparting the above-mentioned high storage elastic modulus to the adhesive layer is not particularly limited, but for example, an urethane acrylate-based oligomer or a polyfunctional acrylate may be formulated for the adhesive component described above. A monomer which is a representative example of an active energy ray-curable compound and which is irradiated with an active energy ray to harden it. In this method, the active energy ray-curable compound is further prepared in the acrylic adhesive solution described above, and then applied to the release film, and after the organic solvent is distilled off, the active energy ray is irradiated to harden it. Just fine. In this case, the ripening for sufficiently reacting the above-described crosslinking agent may be carried out before the irradiation of the active energy ray, or after the irradiation, or may be omitted as appropriate.

An adhesive composition which imparts a high storage elastic modulus in this manner, or a sheet-like adhesive which is further coated on a release film and hardened to impart a high storage elastic modulus is known, and can be produced from an adhesive. Business acquisition. Further, for example, in the pamphlet of International Publication WO 2009/069799, several examples of the adhesive which imparts such a high storage elastic modulus are disclosed.

The thickness of the adhesive layer used in the composite polarizing plate of the present invention is about 5 to 50 μm. Further, when the pressure-sensitive adhesive layer is applied to the retardation film, the surface of the retardation film or the pressure-sensitive adhesive layer may be subjected to a surface treatment such as corona treatment.

[TN mode liquid crystal cell and TN mode liquid crystal panel]

The TN mode liquid crystal cell 11 used in the present invention is used in a liquid crystal cell in a TN mode liquid crystal display device, and is characterized in that, in the cell, the nematic liquid crystal system is disposed in a state of being twisted by 90° in the thickness direction, and is utilized. The white light is realized by penetrating the optical rotation of the linear phase of the liquid crystal phase.

The in-plane retardation value (R _c ) of the TN mode liquid crystal cell 11 used in the present invention is preferably in the range of 300 to 600 nm, more preferably 400 to 500 nm, and most preferably 400 to 470 nm. Here, the "in-plane phase difference value of the liquid crystal cell" means that no voltage is applied.

The composite polarizing plate of the present invention is used in a TN mode liquid crystal cell to form a TN mode liquid crystal panel, and further, when the liquid crystal display device is fabricated, the phase difference between the biaxial retardation film constituting the composite polarizing plate and the TN mode liquid crystal cell The values should satisfy the following formulas (1) and (2).

0.13<R ₀ /R _c ≦0.34 (1)

0.17≦R _th /R _c <0.54 (2)

Here, in the formula, R ₀ , R _th , and R _c are as described below, respectively.

R ₀ (nm): phase difference value of the biaxial retardation film composed of the olefin resin

R _th (nm): thickness direction retardation value of the biaxial retardation film composed of the olefin resin

R _c (nm): In-plane retardation value when no voltage is applied to the liquid crystal cell

Although the formula (1) means that R ₀ /R _{c is} more than 0.13 and is 0.34 or less, the value is more preferably in the range of 0.2 to 0.27. Further, although the formula (2) means that R _th /R _c is 0.17 or more and less than 0.54, the value is more preferably in the range of 0.27 to 0.3. This equation is determined by the experiment, and it is preferable to satisfy the formulas (1) and (2) from the viewpoint of expanding the field of view in the lateral direction. When the relationship between the phase difference values of the biaxial retardation film and the TN mode liquid crystal cell does not satisfy this, the viewing angle in the lateral direction may become narrow.

The TN mode liquid crystal cell 11 is defined such that the transmission axis of the polarizing plate and the rubbing direction of the liquid crystal cell are orthogonal to each other (the rubbing direction of the absorption axis of the polarizing plate and the liquid crystal cell substrate are parallel) is defined as The O mode (Ordinary mode) is arranged such that the transmission axis of the polarizing plate overlaps with the rubbing direction of the liquid crystal cell substrate (the rubbing direction of the absorption axis of the polarizing plate and the liquid crystal cell substrate is orthogonal) Defined as E ordinary mode. Here, the "friction direction of the liquid crystal cell substrate" means an angle at which the liquid crystal cell is viewed from the identification side and is 0° in the longitudinal direction and 45° or 135° in the counterclockwise direction. In the TN mode liquid crystal cell, the nematic liquid crystal is twisted by 90° between the two substrates, and the rubbing direction of the two liquid crystal cell substrates is shifted by 90°.

[Liquid Crystal Display Device]

FIG. 1 shows an example in which the backlight unit 12 is further disposed on one side of the TN mode liquid crystal panel 1 including the two composite polarizing plates 2 and the TN mode liquid crystal cells 11. In this example, although the state of each layer is shown, the adjacent layers are actually adhered. In the example shown in Fig. 1, the backlight unit 12/composite polarizing plate 2/TN mode liquid crystal cell 11/composite polarizing plate 2 is sequentially disposed from below.

In the liquid crystal display device of the present invention, the O mode in which the rubbing direction of the polarizer constituting the composite polarizing plate and the TN mode liquid crystal cell are orthogonal to each other in the rubbing direction of the substrate is used. Any of the E modes in which the transmission axis of the polarizer constituting the composite polarizing plate overlaps with the rubbing direction of the TN mode liquid crystal cell can achieve high display quality. In order to obtain more excellent viewing angle characteristics, the O mode should be used.

The composite polarizing plate 2 is composed of an adhesive layer 6 / a retardation film 5 / a polarizer 3 / a transparent protective layer 4. In the composite polarizing plate, the slow axis 5A of the retardation film 5 and the absorption axis 3A of the polarizer 3 are in an orthogonal relationship, and the polarizer 3 on the lower side is such that the absorption axis 3A is opposed to the long side of the TN mode liquid crystal cell 11. The direction 11A is arranged at 45°, and the upper polarizer 3 is disposed such that the absorption axis 3A thereof is 135° with respect to the longitudinal direction 11A of the TN mode liquid crystal cell 11. In the TN mode liquid crystal cell, the phase difference film 5 side is disposed so that the liquid crystal cells face each other.

Example

Hereinafter, the present invention will be more specifically described by showing examples, but the present invention is not limited by these examples. In the example, "parts" and "%" indicating "usage" or "content" are based on weight unless otherwise specified. The physical property measurement method in the following examples is as follows.

[Measurement of storage elastic modulus]

The storage elastic modulus of the adhesive is determined by the following steps (i) to (iii).

(i) Two samples were taken from the adhesive dose to each of 25 ± 1 mg, and each was formed into a slightly round shape.

(ii) The sample obtained in the above (i) is adhered to the upper and lower surfaces of the I-type jig, and the upper and lower surfaces are gripped by the L-shaped jig to prepare a measurement sample. The composition of the measurement sample is an L-shaped jig-adhesive-type I jig-adhesive-L type jig.

(iii) The measurement sample to be produced is used in a dynamic viscoelasticity measuring apparatus (DVA-220, manufactured by IT Measurement and Control Co., Ltd.) at a temperature of -70 ° C to 200 ° C at a temperature rise temperature of 4 ° C / min and a frequency of 1 Hz. The storage elastic modulus at 23 ° C and 80 ° C was measured under the conditions.

[Determination of phase difference value of retardation film]

The measurement was performed at a wavelength of 590 nm using a phase difference measuring device KOBRA-WR (manufactured by Oji Scientific Instruments Co., Ltd.).

[Determination of phase difference value of liquid crystal cell]

The in-plane retardation value of the liquid crystal cell in which no voltage was applied was measured at a wavelength of 400 nm to 1000 nm using a breakthrough absorption spectrometer MCPD-1000 (manufactured by Otsuka Electronics Co., Ltd.).

[Measurement of light leakage]

The composite polarizing plate or the polarizing plate of the comparative example was cut into two pieces of 237 mm × 421 mm by a cutting device Super cutter rpN1 6001 (manufactured by Takino Seiki Seisakusho Co., Ltd.). In addition, the TN mode liquid crystal cell is prepared by peeling off the originally provided polarizing plate from the TN mode liquid crystal panel which is decomposed and taken out by a TN mode liquid crystal display (TN mode liquid crystal display device) (manufactured by CMI 937A). The in-plane phase difference value Rc of the unapplied voltage state of the TN mode liquid crystal cell was measured and found to be 407 nm.

In the surface of the TN mode liquid crystal cell, the polarizer is in a crossed Nichol state, and the rubbing direction of the substrate of the TN mode liquid crystal cell is parallel to the absorption axis of the polarizer. A composite polarizing plate or a polarizing plate of a comparative example. Then, it was pressurized at 0.5 MPa and 50 ° C for 20 minutes using a pressure cooker (pressure degassing apparatus, manufactured by Kurihara Seisakusho Co., Ltd.) to prepare a TN mode liquid crystal panel for light leakage evaluation.

After the TN mode liquid crystal panel was placed in a hot air circulating oven at 80 ° C for 250 hours, the liquid crystal monitor was assembled and started, and the color distribution measuring device Eye Scale 3W (Eye) was used in an environment of 23 ° C and a relative humidity of 50%. The scale company measured the brightness of the peripheral portion of the display surface on which the black display was formed, and the value obtained by subtracting the brightness of the center from the maximum brightness of the four sides was taken as the amount of light leakage.

Moreover, in the following examples, in the case of the adhesive, an adhesive layer having a thickness of 25 μm was formed into a sheet form from the both sides of the adhesive film, and was sold and given the following. After storing the elastic modulus, the one-side release film is peeled off, and the retardation film or the film replacing the film is attached.

Acrylic Adhesive A: 0.30 MPa was applied at 23 ° C, and a storage elastic modulus of 0.18 MPa was imparted at 80 ° C.

Acrylic Adhesive B: 0.04 MPa was applied at 23 ° C, and a storage elastic modulus of 0.03 MPa was imparted at 80 ° C.

Acrylic Adhesive C: 0.11 MPa was applied at 23 ° C, and a storage elastic modulus of 0.06 MPa was given at 80 ° C.

<Example 1>

A single-side configuration of a polarizer made of polyvinyl alcohol adsorbed with iodine is a triacetyl cellulose membrane (KC8UX2MW, manufactured by Konica Minolta Opto Co., thickness: 80 μm), on the opposite side to make the absorption axis of the polarizer A retardation film made of a cyclic olefin resin is disposed so as to be orthogonal to the slow axis of the retardation film (Zeonor Film, manufactured by Zeon, Japan; R ₀ : 80 nm, R _th : 110 nm, thickness: 40 μm) They are bonded using the respective adhesives. At this time, after the corona discharge treatment was performed on the contact surface side of the retardation film at an integral irradiation amount of 1,680 J, an epoxy-based ultraviolet curable type was applied to each of the retardation film and the triethylene-based cellulose film. The agent is attached to the polarizer. Then, ultraviolet rays were irradiated from the side of the cyclic olefin-based resin film under the conditions of an output of 300 mW and an irradiation amount of 300 mJ using an ultraviolet irradiation system (manufactured by Fusion UV Systems Co., Ltd.) to cure the adhesive to obtain a composite polarizing plate. On the side of the cyclic olefin-based resin film of the composite polarizing plate, the corona discharge treatment was carried out under the conditions of an integral irradiation amount of 1,680 J, and then the acrylic pressure-sensitive adhesive A was bonded.

Using the composite polarizing plate produced in this manner, the amount of light leakage was measured by the above method, and it was 0.8 cd/m ² . Further, the relationship between the in-plane retardation value R _{0 of the} retardation film and the thickness direction phase difference R _th and the phase difference R _c of the liquid crystal cell and the N _z coefficient are as follows.

R ₀ /R _c =0.20

R _th /R _c =0.27

N _z = 1.9

<Example 2>

A composite polarizing plate was produced in the same manner as in Example 1 except that the triethylenesulfonyl cellulose film was replaced with a biaxially stretched polyethylene terephthalate film (thickness: 38 μm, haze: 2.3%). . The amount of light leakage was evaluated to be 1.0 cd/m ² using a TN mode liquid crystal monitor composed of a TN mode liquid crystal panel to which the composite polarizing plate was attached.

<Comparative Example 1>

In addition to the retardation film composed of the cyclic olefin resin, the viewing angle compensation film (EA-WV film, manufactured by Fujifilm Co., Ltd.) in which the disk-shaped liquid crystal is oriented and fixed to the triethylenesulfonyl cellulose film is replaced. In the same manner as in Example 1, a composite polarizing plate was produced. The amount of light leakage was evaluated to be 8.2 cd/m ² using a TN mode liquid crystal monitor composed of a TN mode liquid crystal panel to which the composite polarizing plate was attached.

<Comparative Example 2>

The retardation film composed of the cyclic olefin resin was prepared in the same manner as in Example 1 except that a triacetyl cellulose film (KC8UX2MW, manufactured by Konica Minolta Opto Co., Ltd., thickness: 80 μm) was replaced. Polarizer. The amount of light leakage was evaluated to be 1.3 cd/m ² using a TN mode liquid crystal monitor composed of a TN mode liquid crystal panel to which the polarizing plate was attached.

<Comparative Example 3>

The retardation film composed of the cyclic olefin resin was replaced with a triethylenesulfonated cellulose film (the same thickness as the user of Comparative Example 2, 80 μm), and the acrylic adhesive A was adhered with acrylic. A polarizing plate was produced in the same manner as in Example 1 except that the agent B was replaced. The amount of light leakage was evaluated to be 3.7 cd/m ² using a TN mode liquid crystal monitor composed of a TN mode liquid crystal panel to which the polarizing plate was attached.

<Comparative Example 4>

A composite polarizing plate was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive A was replaced with an acrylic pressure-sensitive adhesive C. The amount of light leakage was evaluated using a TN mode liquid crystal monitor composed of a TN mode liquid crystal panel to which the composite polarizing plate was attached, and was 7.1 cd/m ² .

The main constitutions and results in the above examples and comparative examples are summarized in Table 1.

In Table 1, "TAC" and "PET" in the column of "transparent protective layer" mean the following resins, respectively.

TAC: triethylenesulfonyl cellulose

PET: polyethylene terephthalate

<Example 3> (a) Production of composite polarizer

On one side of a polarizer for adsorbing iodine on a polyvinyl alcohol, a triacetyl cellulose film (KC8UX2MW, manufactured by Konica Minolta Opto Co., Ltd.) having a thickness of 80 μm as a transparent protective layer was disposed and disposed on the opposite side of the polarizer. A retardation film (obtained from Zeon, Japan; R ₀ = 80 nm, R _th = 110 nm) having a thickness of about 40 μm composed of a cyclic olefin resin was used to prepare a composite polarizing plate. At this time, first, the corona discharge treatment was performed on the contact surface side of the retardation film at an integrated irradiation amount of 1680 J, and then the adhesion surface of the retardation film and the protective film made of triacetyl cellulose were applied. Each of the surfaces was coated with an epoxy-based ultraviolet curable adhesive, and bonded to a polarizer. Then, ultraviolet rays were irradiated from the retardation film side under the conditions of an output of 300 mW and an irradiation amount of 300 mJ using an ultraviolet irradiation system manufactured by Fusion UV Systems Co., Ltd. to cure the adhesive. Further, an adhesive layer composed of an acrylic adhesive C (storage elastic modulus: 0.11 MPa at 23 ° C and 0.06 MPa at 80 ° C) having a thickness of about 15 μm was provided on the retardation film side, and was prepared. A composite polarizer with an adhesive. Although a composite polarizing plate with an adhesive attached to a separate film on the outer side of the adhesive layer was produced, the thickness of the composite polarizing plate with the adhesive removed from the separation film was 170.6 μm.

(b) Production of liquid crystal panel

The liquid crystal panel "CMV 937A" made of Chi Mei Electronics Co., Ltd. having a TN mode liquid crystal cell is disassembled to remove the liquid crystal panel, and the polarizing plate attached to both sides of the liquid crystal cell is peeled off from the liquid crystal panel, and instead, (a) The composite polarizing plate with the adhesive attached is peeled off from the separation film so that both sides of the film are bonded to the adhesive layer side in such a manner that the axis of penetration of the liquid crystal cell is orthogonal to each other (this configuration is called O Mode), making a liquid crystal panel. The layer configuration and the axial relationship at this time are as shown in Fig. 1.

The in-plane phase difference value of the TN mode liquid crystal cells used herein was 410 nm. Therefore, the relationship between the in-plane retardation value R ₀ and the thickness direction retardation value R _th of the retardation film composed of the cyclic olefin resin and the in-plane retardation value R _C of the TN mode liquid crystal cell is R ₀ /R. _c = 80/410 = 0.20, R _th / R _c = 110 / 410 = 0.27.

(c) Assembly and evaluation of liquid crystal display devices

The liquid crystal panel was changed to the one produced in the above (b), and the liquid crystal display device was assembled in the same state as the liquid crystal television before the decomposition. When the liquid crystal display device was activated, the liquid crystal viewing angle measuring device "EZ Contrast 88XL" manufactured by ELDIM Co., Ltd. was used to measure the angle at which the contrast in the horizontal direction of the screen was 100 or more. Here, "contrast" refers to the ratio of the brightness in white display to the brightness in black display. In addition, "the angle in which the contrast in the horizontal direction of the screen is 100 or more" means that the contrast is made centering on the normal direction 62 of the display surface 61 of the liquid crystal panel 60 in the schematic cross-sectional view of the liquid crystal panel shown in FIG. When the measurement position is inclined to the left and right of the screen, the angle 63 in the direction on the right side of the screen is 100 and the contrast is 100 in the direction on the left side of the screen. Here, the screen is divided into two positions (vertical direction). The center portion) measures the contrast when viewed from the direction in which the screen is tilted left and right. The results are shown in Table 2. In Table 2, the angle at which the above contrast is 100 or more is expressed as "a viewing angle of CR 100 or more".

<Example 4>

A liquid crystal panel was produced in the same manner as in Example 3 except that the retardation film composed of the cyclic olefin resin was used, except that R ₀ was 60 nm and R _th was 70 nm. Further, a liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

<Example 5>

A liquid crystal panel was produced in the same manner as in Example 3 except that the retardation film composed of the cyclic olefin resin was used, and R ₀ was 60 nm and R _th was 90 nm. Further, a liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

<Example 6>

A liquid crystal panel was produced in the same manner as in Example 3 except that the retardation film composed of the cyclic olefin resin was used, and R ₀ was 60 nm and R _th was 110 nm. Further, a liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

<Example 7>

A liquid crystal panel was produced in the same manner as in Example 3 except that R ₀ was 110 nm and R _th was 150 nm, and a liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

<Example 8>

A liquid crystal panel was produced in the same manner as in Example 3 except that R ₀ was 140 nm and R _th was 125 nm, and a liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

<Example 9>

In addition to the retardation film composed of the cyclic olefin resin, R ₀ is 90 nm and R _th is 130 nm, and a liquid crystal television "REGZA 19A3500" manufactured by Toshiba Co., Ltd. having a TN mode liquid crystal cell is used (no voltage is applied). A liquid crystal panel was produced in the same manner as in Example 3 except that the in-plane retardation value of the liquid crystal cell was 460 nm. Further, the liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

<Example 10>

In addition to the use of a biaxially oriented polyethylene terephthalate film having a thickness of about 38 μm and a haze of 2.3% (the maximum value of the deformation of the oriented major axis is 4.5 degrees, the in-plane retardation value R ₀ is 2245 nm) instead of triethylene hydride. The base cellulose film was subjected to a corona discharge treatment under the conditions of an integrated irradiation amount of 1,680 J on the film-attached surface side of the polarizer, and then the adhesive was applied, and the same procedure as in the case of (a) of Example 3 was carried out. A composite polarizing plate with an adhesive is produced. The composite polarizing plate with an adhesive was removed to a thickness of 129.1 μm from the separation membrane (including the adhesive layer). A liquid crystal panel was produced in the same manner as in Example 3 (b) except that the composite polarizing plate was used, and a liquid crystal display device was assembled and evaluated in the same manner as in (c) of the third embodiment. The results are shown in Table 2.

<Example 11>

An unoriented cyclic olefin-based resin film having a thickness of about 23 μm and a haze of 0% (obtained from Zeon, Japan); in-plane retardation value R ₀ =1.3 nm, thickness direction retardation R _th =2.6 Instead of the triethylenesulfonated cellulose film, the other method was the same as in the case of (a) of Example 3, and a composite polarizing plate with an adhesive was prepared. The composite polarizing plate with an adhesive was removed to have a thickness of 114.1 μm from the separation membrane (including the adhesive layer). The composite polarizing plate was bonded to the back side of the liquid crystal cell (backlight side), and the composite polarizing plate produced in Example 11 was bonded to the front side (identification side) of the liquid crystal cell, and the other system was the same as that of Example 3 (b). In the same manner, a liquid crystal panel was produced, and a liquid crystal display device was assembled and evaluated in the same manner as in (c) of the third embodiment. The results are shown in Table 2.

<Comparative Example 5>

In addition to an optical compensation film ("EA-WV" manufactured by Fujifilm Co., Ltd.) in which a disk-shaped liquid crystal is oriented and fixed to a triethylenesulfonyl cellulose film, instead of a retardation film composed of a cyclic olefin resin, In the same manner as in Example 3, a composite polarizing plate was produced, and further, a liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

<Comparative Example 6>

The film was produced in the same manner as in Example 3, except that a triacetyl cellulose film ("KC8UX2MW" manufactured by Konica Minolta Opto Co., Ltd.) having a thickness of 80 μm was used instead of the retardation film composed of a cyclic olefin resin. The liquid crystal panel was further evaluated by assembling a liquid crystal display device. The results are shown in Table 2.

<Comparative Example 7>

Alternatively except retardation R ₀ from a cyclic olefin based resin film composed of 55nm to 124nm, and those of R _th, the rest of the system in Example 3 likewise produced a liquid crystal panel, further, the liquid crystal display device is assembled evaluated. The results are shown in Table 2.

<Comparative Example 8>

A liquid crystal panel was produced in the same manner as in Example 3 except that a retardation film composed of a cyclic olefin resin was used instead of R ₀ of 60 nm and R _th was 220 nm, and a liquid crystal display device was assembled and evaluated. The results are shown in Table 2.

The main constitutions and results in the above Examples 3 to 11 and Comparative Examples 5 to 8 are summarized in Table 2.

In Table 2, "TAC", "PET" and "COP" in the column of "transparent protective layer" mean the following resins.

TAC: triethylenesulfonyl cellulose

PET: polyethylene terephthalate

COP: cyclic olefin resin

<Example 12>

The liquid crystal panel produced in Example 3 was vertically placed in a hot air circulation oven set to 80 °C. After 300 hours passed, the liquid crystal panel was taken out, cooled to room temperature, assembled in a liquid crystal display device, and started. When the image is displayed in black and observed, no light leakage can be seen anywhere on the surface.

<Comparative Example 9>

The liquid crystal panel produced in Comparative Example 5 was placed in a hot air circulation oven in the same manner as in Example 12, and after the same period of time, it was taken out and cooled to room temperature, and then assembled in a liquid crystal display device and started up. After the image is displayed in black and observed, the light leakage is observed along the four sides of the drawing.

1. . . TN mode LCD panel

2. . . Composite polarizer

3. . . Polarizer

3A. . . Absorber axis

4. . . Transparent protective layer

5. . . Phase difference film

5A. . . Slow axis of retardation film

6. . . Adhesive layer

11. . . TN mode liquid crystal cell

11A. . . Long-side direction of TN mode liquid crystal cell

12. . . Backlight unit

60. . . LCD panel

61. . . LCD panel display surface

62. . . Display the normal direction of the face

63. . . angle

Fig. 1 is an exploded perspective view schematically showing a TN mode liquid crystal panel using a composite polarizing plate of a preferred example of the present invention.

Fig. 2 is a schematic cross-sectional view of a liquid crystal panel for explaining a contrast angle of view in the lateral direction.

1. . . TN mode LCD panel

2. . . Composite polarizer

3. . . Polarizer

3A. . . Absorber axis

4. . . Transparent protective layer

5. . . Phase difference film

5A. . . Slow axis of retardation film

6. . . Adhesive layer

11. . . TN mode liquid crystal cell

11A. . . Long-side direction of TN mode liquid crystal cell

12. . . Backlight unit

Claims (6)

A TN mode liquid crystal panel in which a transparent protective layer, a polarizer, a biaxial retardation film composed of an olefin resin, and a composite polarizing plate formed of an adhesive layer are sequentially laminated to make the composite polarizing plate The retardation film side and the TN mode liquid crystal cell side are laminated on the both sides of the TN mode liquid crystal cell, and the biaxial retardation film system composed of the olefin resin is used. When the refractive indices in the in-plane slow axis direction, the in-plane fast axis direction, and the thickness direction measured by light having a wavelength of 590 nm are n _x , n _{y ,} and n _z , respectively, the in-plane phase defined by the following formula (I) The difference R ₀ is 40 to 150 nm, and the phase difference R _{th in} the thickness direction defined by the following formula (II) is 50 to 250 nm, and the N _z coefficient defined by the following formula (III) is more than 1 and 7 or less. ;R ₀ =(n _x -n _y )×d (I) R _th =[(n _x +n _y )/2-n _z ]×d (II) N _z =(n _x -n _z )/( n _{x -} n _y ) (III) Further, when the in-plane retardation value when the voltage is not applied to the liquid crystal cell is R _c , the following formulas (1) and (2) are satisfied: 0.13 < R ₀ / R _c ≦ 0.34 (1) 0.17≦R _th /R _c <0.54 (2). The TN mode liquid crystal panel according to claim 1, wherein the retardation film is made of a cyclic olefin resin. The TN mode liquid crystal panel according to claim 1, wherein the transparent protective layer in the composite polarizing plate disposed on at least one side of the liquid crystal cell is extended to have a thickness of 20 to 50 μm. It is composed of a polyethylene terephthalate film having a haze value of 0.1 to 40%. The TN mode liquid crystal panel according to claim 1, wherein the transparent protective layer in the composite polarizing plate disposed on one side of the liquid crystal cell is a ring that is not extended and has a thickness of 15 to 25 μm. It is composed of an olefin-based resin film. The TN mode liquid crystal panel according to the first aspect of the invention, wherein the polarizer and the transparent protective layer and/or the polarizer and the retardation film are via a solventless epoxy-based adhesive. . The TN mode liquid crystal panel according to claim 5, wherein the solventless epoxy-based adhesive is cured by cationic polymerization by irradiation with an active energy ray.