JP5569773B2 - Composite polarizing plate and IPS mode liquid crystal display device using the same - Google Patents

Description

  The present invention relates to a composite polarizing plate in which a transparent protective film is bonded to one surface of a polarizing film and a retardation film is bonded to the other surface, and an IPS mode liquid crystal display device using the same.

  Liquid crystal display devices are used in various display devices by taking advantage of features such as low power consumption, operation at a low voltage, light weight and thinness. The liquid crystal display device is composed of many materials such as a liquid crystal cell, a polarizing film, a retardation film, a light collecting sheet, a diffusion film, a light guide plate, and a light reflecting sheet. Therefore, improvements aimed at productivity, weight reduction, brightness improvement, etc. are actively performed by reducing the number of constituent films or reducing the thickness of the film or sheet.

  Furthermore, a liquid crystal display device is required to have a product that can withstand severe durability conditions. For example, a liquid crystal display device for a car navigation system may have a very high temperature and humidity in the vehicle in which it is placed, a display for a mobile phone, a portable terminal device, a display for a TV, a computer, etc. However, depending on the use environment and the installation location, the temperature and humidity may be exposed to severe conditions, so that product performance that can withstand use under such severe conditions is required.

  The polarizing plate usually has a structure in which a transparent protective film is laminated on both sides or one side of a polarizing film made of a polyvinyl alcohol-based resin film adsorbed and oriented with a dichroic dye. The polarizing film is produced by a method in which a polyvinyl alcohol-based resin film is longitudinally uniaxially stretched and dyed with a dichroic dye, then treated with boric acid to cause a crosslinking reaction, and then washed with water and dried. As the dichroic dye, iodine or a dichroic organic dye is used. A protective film is laminated on both or one side of the polarizing film thus obtained to form a polarizing film, which is used by being incorporated in a liquid crystal display device. As the protective film, a cellulose acetate resin film typified by triacetylrose is often used, and the thickness thereof is usually about 30 to 120 μm. In addition, an adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin is often used for laminating the protective film.

  When the polarizing plate composed of such a member is used for a long time under wet heat conditions, the polarizing performance may be deteriorated or the protective film and the polarizing film may be easily peeled off.

  Therefore, there is an attempt to configure at least one protective film with a resin other than cellulose acetate. For example, in JP-A-8-43812 (Patent Document 1), in a polarizing film in which protective films are laminated on both sides of a polarizing film, at least one of the protective films is a thermoplastic norbornene-based material having a retardation film function. It is described that it is made of resin. Japanese Patent Application Laid-Open No. 9-325216 (Patent Document 2) describes that at least one of the protective layers of the polarizing film is composed of a birefringent film.

  On the other hand, since the styrene resin film has a larger side chain polarizability than the main chain polarizability of the styrene resin (it may be negatively polarized), the negative retardation film has a large refractive index in the thickness direction. As being considered. However, styrene resin films have problems in heat resistance, mechanical strength, and chemical resistance, and have not yet been put into practical use.

Here, the negative retardation film having a large refractive index in the thickness direction, the refractive index of the maximum refractive index direction in the plane (slow axis direction) n _x, the direction perpendicular thereto in the plane (fast axis direction the refractive index n _y in), when the refractive index in the thickness direction is n _z, has a relationship of _{n z ≒ n x> n y} , in _{(n x -n z) / (} n x -n y) It is a film having a defined Nz coefficient of approximately 0 (zero).

  It is known that the heat resistance of a styrene resin can be improved by copolymerizing a monomer that forms a resin having a high glass transition temperature (hereinafter abbreviated as Tg), such as norbornene or maleic anhydride. However, mechanical strength and chemical resistance are not sufficient.

  Many techniques have been proposed in which other monomers are copolymerized with styrene, or other resin layers are laminated on a styrene-based film. For example, JP 2002-517583 A (Patent Document 3) describes that an essentially random copolymer of an aromatic vinyl monomer and an α-olefin, typically styrene, is used as a film. It has also been suggested to have a multilayer structure of the film and other polymer layers. In addition, JP-A-2003-50316 (Patent Document 4) and JP-A-2003-207640 (Patent Document 5) include an acyclic olefin monomer and a cyclic olefin monomer in an aromatic vinyl monomer typified by styrene. It is described that a copolymerized terpolymer is used as a retardation film. Furthermore, in JP-A-2003-90912 (Patent Document 6), an orientation film made of a norbornene resin and an orientation film made of a styrene-maleic anhydride copolymer resin are laminated via an adhesive layer, and a phase difference is obtained. JP, 2004-167823, A (patent documents 7) describes laminating a polystyrene sheet on a polyolefin multilayer film. Furthermore, in JP-A-2006-192537 (Patent Document 8), a first layer made of a styrene resin film and a second layer made of an acrylic resin composition in which rubber particles are blended are used as an adhesive. It is described that the film is laminated without using a layer to form a retardation film.

  By the way, in the IPS mode, which is one of the drive modes of the liquid crystal cover device, the liquid crystal molecules are aligned in substantially the same direction and in the same direction as the substrate surface. Excellent characteristics. However, even in various liquid crystal display devices with improved viewing angle characteristics including the IPS mode, viewing angle dependency still occurs.

  Various measures have been proposed to compensate for the viewing angle dependency of the IPS mode liquid crystal display device. As one of them, a method of compensating the viewing angle of the polarizing plate with a retardation plate is effective. For example, in Japanese Patent Laid-Open No. 2-160204 (Patent Document 9), the ratio of the retardation when incident from the vertical direction and the retardation when incident from a direction inclined by 40 degrees from the normal is within a certain range. A retardation film, for example, a retardation film oriented in the thickness direction is described. Japanese Patent Laid-Open No. 7-230007 (Patent Document 10) discloses a retardation film in which a uniaxially stretched thermoplastic resin film is caused to undergo thermal shrinkage in a predetermined form and the retardation angle dependency is controlled, for example, A retardation film oriented in the thickness direction is also described. Such a retardation plate oriented in the thickness direction is transmitted through an adjacent polarizing plate between one of the two polarizing plates arranged with the liquid crystal cell interposed therebetween and the liquid crystal cell substrate. Arranging so that the axis and the slow axis of the phase difference plate are parallel is effective in compensating the viewing angle.

  T. Ishinab et al. , "Novel Wide Viewing Angle Polarizer with High Achromaticity", SID 00 DIGEST, p. 1094-1097 (Non-Patent Document 1) describes that a thickness-oriented retardation plate having Nz coefficients of 0.25 and 0.8 as defined above is more effective. Furthermore, in JP-A-11-133408 (Patent Document 11), for the IPS mode, a retardation film (compensation) having an optical axis in the direction perpendicular to the substrate surface with positive uniaxiality between the liquid crystal cell substrate and the polarizing plate. Layer), that is, disposing a retardation film uniaxially oriented in the thickness direction.

  However, these thickness-oriented retardation plates have poor productivity and require precise processing, so that the product becomes expensive.

  Furthermore, for compensation of the viewing angle dependency of the IPS mode liquid crystal display device, a retardation plate (optical compensation sheet) having negative uniaxiality is mounted between the liquid crystal cell substrate and at least one polarizing plate. JP, 10-54982, A (patent documents 12) describes that viewing angle dependency is improved. This publication shows an example in which the optical axis of a retardation film having negative uniaxiality, that is, the fast axis is arranged in parallel with the major axis of liquid crystal molecules. Therefore, it is desired that the above optical compensation film is laminated on a polarizing plate and supplied as an optical compensation film integrated polarizing plate. However, in the configuration of optical compensation proposed so far, problems such as color shift and tone inversion have not been sufficiently solved, and further optimization is desired.

  In addition, when two or more retardation films are laminated and used, even if the orientation angle distribution of each retardation film is uniform, when they are laminated, color unevenness may occur at specific locations, It was a problem.

JP-A-8-43812 Japanese Patent Laid-Open No. 9-325216 Japanese translation of PCT publication No. 2002-517583 JP 2003-50316 A JP 2003-207640 A JP 2003-90912 A JP 2004-167823 A JP 2006-192637 A JP-A-2-160204 Japanese Unexamined Patent Publication No. 7-230007 JP 11-133408 A Japanese Patent Laid-Open No. 10-54982

T.A. Ishinab et al. , "Novel Wide Viewing Angle Polarizer with High Achromaticity", SID 00 DIGEST, p. 1094-1097 (2000)

  An object of the present invention is to provide a composite polarizing plate that includes an easily manufactured retardation plate and exhibits excellent viewing angle characteristics when applied to a liquid crystal display device. Another object of the present invention is to provide a composite polarizing plate which is less likely to cause local color unevenness while two retardation films are laminated. Still another object of the present invention is to provide a liquid crystal display device having an IPS mode liquid crystal cell and excellent in viewing angle characteristics.

  According to the present invention, a transparent protective film is laminated on one surface of a polarizing film via a first adhesive layer, and the other surface of the polarizing film is made of an olefin resin via a second adhesive layer. (Meth) acryl is laminated with a first retardation film, and further contains rubber particles on both sides of a core layer made of a styrene resin via an adhesive layer on the outside of the first retardation film. A composite polarizing plate is provided in which a second retardation film having a three-layer structure in which a skin layer made of a resin composition is formed is laminated.

The first retardation film has an in-plane retardation is is 30 to 150 nm, the in-plane slow axis direction, the in-plane fast axis direction and the refractive index in the thickness direction, respectively n _x, and n _y and n _z when the _{formula: (n x -n z) /} (n x -n y) Nz coefficient defined by less than 2 more than 1, i.e., the following equation (1):
_{1 <(n x -n z)} / (n x -n y) <2 (1)
The second retardation film has an in-plane retardation of 20 to 120 nm, and the Nz coefficient defined above is more than −2 and less than −0.5, That is, the following formula (2):
_{-2 <(n x -n z)} / (n x -n y) <- 0.5 (2)
It is preferable to have refractive index anisotropy satisfying

  The first retardation film and the second retardation film are preferably laminated so that the change in the angle between the orientation angles of the first retardation film and the second retardation film is 0.4 ° or less between 10 cm.

  The olefin resin constituting the first retardation film is preferably a cyclic olefin resin mainly containing a structural unit derived from an alicyclic olefin.

  In the second retardation film, the glass transition temperature of the styrene resin constituting the core layer is preferably 120 ° C. or higher, and the glass transition temperature of the (meth) acrylic resin composition constituting the skin layer is preferably It is preferable that it is 120 degrees C or less.

  The first retardation film made of an olefin-based resin and the polarizing film can be bonded with an aqueous adhesive made of an aqueous solution of a water-soluble polyvinyl alcohol-based resin, and the aqueous adhesive contains a water-soluble epoxy compound. It is preferable to do. The first retardation film and the polarizing film can also be bonded with an adhesive made of an epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating. When using an epoxy resin composition as an adhesive, the epoxy resin preferably has at least one epoxy group bonded to an alicyclic ring in the molecule.

  Furthermore, according to the present invention, there is provided an ISP mode liquid crystal display device in which any one of the above polarizing plates is disposed on at least one surface of an IPS mode liquid crystal cell. Further, any one of the above polarizing plates is arranged on one surface of the IPS mode liquid crystal cell, and the other surface has an in-plane retardation of 10 nm or less and a transparent thickness direction retardation of 15 nm or less. An IPS mode liquid crystal display device in which a polarizing plate having a protective film on the liquid crystal cell side is also provided.

  The in-plane retardation Re of the film is a value obtained by multiplying the in-plane refractive index difference by the film thickness, and is defined by the following formula (3). The thickness direction retardation Rth of the film is a value obtained by multiplying the difference between the in-plane average refractive index and the refractive index in the thickness direction by the thickness of the film, and is defined by the following formula (4). Further, as described in relation to the previous equations (1) and (2), the Nz coefficient is defined by the following equation (5).

Plane retardation value _{Re = (n x -n y)} × d (3)
Thickness direction retardation value _{Rth = {(n x + n} y) / 2-n z} × d (4)
Nz factor _{= (n x -n z) /} (n x -n y) (5)
(Where _nx , _ny and _nz are the triaxial refractive indices of the film as defined above and d is the film thickness).

  The Re, Rth and Nz coefficients can be measured using various commercially available phase difference meters. These values are typically representative values measured at a wavelength near the center of visible light, but the retardation value and Nz coefficient referred to in this specification are values measured at a wavelength of 590 nm. is there.

It is a cross-sectional schematic diagram which shows an example of a layer structure of the composite polarizing plate of this invention. 6 is a distribution diagram of contrast ratio of a liquid crystal display device manufactured using the composite polarizing plate of Example 1. FIG. 6 is a distribution diagram of contrast ratio of a liquid crystal display device manufactured using the composite polarizing plate of Example 2. FIG. 6 is a distribution diagram of contrast ratio of a liquid crystal display device manufactured using the composite polarizing plate of Example 3. FIG. 6 is a distribution diagram of contrast ratio of a liquid crystal display device manufactured using the composite polarizing plate of Example 4. FIG. 6 is a contrast ratio distribution diagram of a liquid crystal display device manufactured using the composite polarizing plate of Comparative Example 1. FIG. 10 is a distribution diagram of contrast ratio of a liquid crystal display device manufactured using the composite polarizing plate of Example 5. FIG. It is the graph which plotted the angle which the orientation angle | corner of the two retardation films which comprise each about the two types of composite polarizing plate used in Example 5 formed in the width direction.

[Composite polarizing plate]
FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the composite polarizing plate of the present invention. A composite polarizing plate 100 shown in FIG. 1 includes a polarizing plate in which a transparent protective film 102, a polarizing film 101, and a first retardation film 103 made of an olefin resin are laminated in this order, and a first polarizing plate of the polarizing plate. And a second retardation film 105 laminated on the retardation film 103 with an adhesive layer 104 interposed therebetween. A transparent protective film 102 is laminated on one surface of the polarizing film 101 via a first adhesive layer 106, and a second layer made of an olefin resin is formed on the other surface of the polarizing film 101 via a second adhesive layer 107. 1 retardation film 103 is laminated. The second retardation film 105 has a three-layer structure in which skin layers 32 and 32 made of a (meth) acrylic resin composition containing rubber particles are formed on both surfaces of a core layer 31 made of a styrene resin. . The surface of the second retardation film 105 opposite to the surface bonded to the first retardation film 103 is usually provided with an adhesive layer 108 for bonding to other members such as a liquid crystal cell, A separator 109 that temporarily protects the surface of the pressure-sensitive adhesive layer 108 until bonding to another member is provided on the outside thereof. In FIG. 1, some layers are shown separated for the sake of clarity, but in actuality, adjacent layers are closely bonded. Hereinafter, each member which comprises a composite polarizing plate is demonstrated in detail.

[Polarized film]
The polarizing film 101 used in the present invention usually adsorbs a dichroic dye by uniaxially stretching a polyvinyl alcohol resin film by a known method, and dyeing the polyvinyl alcohol resin film with a dichroic dye. It is manufactured through a step, a step of treating a polyvinyl alcohol-based resin film adsorbed with a dichroic dye with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution.

  As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The film thickness of the polyvinyl alcohol-based raw film is not particularly limited, but is, for example, about 10 μm to 150 μm.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

  In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which a polyvinyl alcohol resin film is stretched using a solvent such as water. The draw ratio is usually about 3 to 8 times.

  As a method of dyeing the polyvinyl alcohol resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. Further, the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight and preferably about 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

  The boric acid treatment after dyeing with a dichroic dye is usually performed by immersing the dyed polyvinyl alcohol resin film in a boric acid-containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight and preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. Further, the immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain a polarizing film. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, and preferably 50 to 80 ° C. The time for the drying treatment is usually about 60 to 600 seconds, and preferably 120 to 600 seconds.

  By the drying treatment, the moisture content of the polarizing film is reduced to a practical level. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. Moreover, when a moisture content exceeds 20 weight%, the thermal stability of a polarizing film may be inferior.

  Thus, the thickness of the polarizing film obtained by adsorbing and orienting the dichroic dye can usually be about 5 to 40 μm.

[First retardation film made of olefin resin]
In the composite polarizing plate of the present invention, the first retardation film 103 disposed on the liquid crystal cell side is made of an olefin resin. The olefin resin is a chain aliphatic olefin such as ethylene and propylene, or a structural unit derived from an alicyclic olefin such as norbornene or a substituted product thereof (hereinafter collectively referred to as norbornene monomer). It becomes resin. The olefin resin may be a copolymer using two or more kinds of monomers.

  Among them, as the olefin resin, a cyclic olefin resin that is a resin mainly containing a structural unit derived from an alicyclic olefin is preferably used. Typical examples of the alicyclic olefin constituting the cyclic olefin resin include a norbornene monomer. Norbornene is a compound in which one carbon-carbon bond of norbornane is a double bond, and according to IUPAC nomenclature, it is named bicyclo [2,2,1] hept-2-ene. is there. Examples of substituted norbornene include 3-substituted, 4-substituted, 4,5-disubstituted, etc., with the norbornene double bond position being 1,2-position. Cyclopentadiene, dimethanooctahydronaphthalene, and the like can also be used as monomers constituting the cyclic olefin resin.

  The cyclic olefin-based resin may or may not have a norbornane ring in its structural unit. Examples of the norbornene-based monomer that forms a cyclic olefin-based resin having no norbornane ring as a structural unit include, for example, those that become a 5-membered ring by ring opening, typically norbornene, dicyclopentadiene, 1- or 4- Examples thereof include methyl norbornene and 4-phenyl norbornene. When the cyclic olefin resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be a polymer.

  More specific examples of cyclic olefin resins include, for example, ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers and other monomers, addition of maleic acid and cyclopentadiene, etc. Examples of the polymer-modified product, a polymer or copolymer obtained by hydrogenation of these, an addition polymer of a norbornene monomer, an addition copolymer of a norbornene monomer and another monomer, and the like. Examples of other monomers in the case of a copolymer include α-olefins, cycloalkenes, and non-conjugated dienes. Moreover, the cyclic olefin resin may be a copolymer using one or more of norbornene monomers and other alicyclic olefins.

  Among the above specific examples, as the cyclic olefin resin, a resin obtained by hydrogenating a ring-opening polymer using a norbornene monomer is preferably used. Such a cyclic olefin-based resin can be subjected to a stretching treatment to obtain a retardation film, and in addition to stretching, a shrinkable film having a predetermined shrinkage rate is bonded together to perform a heat shrinking treatment, A retardation film having high uniformity and a large retardation value can also be obtained.

  Commercially available cyclic olefin resins using such norbornene-based monomers are all sold under the trade names “ZEONEX”, “ZEONOR”, and JSR Corporation, which are sold by Nippon Zeon Co., Ltd. There is "Arton" etc. Commercial products are also available for these cyclic olefin-based resin films and stretched films, for example, “Zeonor Film” and JSR Co., Ltd., both of which are sold by Nippon Zeon Co., Ltd. There are “Arton Film” sold and “Essina” sold by Sekisui Chemical Co., Ltd.

  In addition, as the first retardation film used in the present invention, a film made of a mixed resin containing two or more kinds of olefin resins or a film made of a mixed resin of an olefin resin and another thermoplastic resin is used. You can also. For example, examples of the mixed resin containing two or more types of olefin resins include a mixture of a cyclic olefin resin and a chain aliphatic olefin resin as described above. When a mixed resin of an olefin resin and another thermoplastic resin is used, another thermoplastic resin is appropriately selected depending on the purpose. Specific examples include polyvinyl chloride resin, cellulose resin, polystyrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, (meth) acrylic resin, polyvinyl acetate resin, polyvinyl chloride. Vinylidene resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyether Examples include ether ketone resins, polyarylate resins, liquid crystalline resins, polyamideimide resins, polyimide resins, polytetrafluoroethylene resins, and the like. These thermoplastic resins can be used alone or in combination of two or more. The thermoplastic resin can also be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, and stereoregularity imparting.

  When a mixed resin of an olefin resin and another thermoplastic resin is used, the content of the other thermoplastic resin is usually about 50% by weight or less and preferably about 40% by weight or less based on the whole resin. By setting the content of other thermoplastic resins within this range, the retardation value film has a small absolute value of the photoelastic coefficient, exhibits good wavelength dispersion characteristics, and is excellent in durability, mechanical strength and transparency. Can be obtained.

  Such an olefin resin can be formed into a film by a casting method from a solution, a melt extrusion method, or the like. When a film is formed from two or more kinds of mixed resins, the film forming method is not particularly limited. For example, a uniform solution obtained by stirring and mixing resin components with a solvent at a predetermined ratio is used. A method of producing a film by a casting method, a method of melt-mixing resin components at a predetermined ratio, and producing a film by a melt extrusion method are employed.

  The film made of the olefin-based resin may contain other components such as a residual solvent, a stabilizer, a plasticizer, an anti-aging agent, an antistatic agent, and an ultraviolet absorber as necessary, as long as the object of the present invention is not impaired. You may contain. Moreover, a leveling agent can also be contained in order to reduce the surface roughness.

  The first retardation film composed of the olefin resin film used in the present invention has an in-plane retardation Re of 30 to 150 nm, an Nz coefficient defined by the formula (5) of more than 1, and less than 2. It preferably has a refractive index anisotropy of

  The olefin resin film having refractive index anisotropy as described above can be obtained by known longitudinal uniaxial stretching, tenter transverse uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, etc., and a desired retardation value. In addition to appropriately adjusting the stretching ratio and the stretching speed so as to obtain a temperature, various temperatures such as a preheating temperature during stretching, a stretching temperature, a heat setting temperature, and a cooling temperature, and a pattern thereof may be appropriately selected.

  The stretched cyclic olefin-based resin film used in the present invention preferably has a thickness in the range of 20 to 80 μm, and more preferably in the range of 40 to 80 μm. When the thickness of the cyclic olefin-based resin film is less than 20 μm, it is difficult to handle the film, and a predetermined retardation value tends to be difficult to be expressed. On the other hand, when the thickness exceeds 80 μm, Inferior in transparency, transparency may be lowered, and the weight of the obtained polarizing plate may be increased.

[Transparent protective film]
The transparent protective film 102 laminated on one surface of the polarizing film is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. The material constituting such a transparent protective film is not particularly limited. For example, a (meth) acrylic resin having a methyl methacrylate resin as a representative example, a polyolefin resin having a polypropylene resin as a representative example, a cyclic resin Olefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, acrylonitrile / butadiene / styrene copolymer resins, acrylonitrile / styrene copolymer resins, polyvinyl acetate resins, polyvinylidene chloride resins, polyamide resins Resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyamideimide resins Fat, and polyimide resin.

  These resins can be used alone or in combination of two or more. These resins can also be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between different polymers. Modifications such as mixing including the accompanying cases can be mentioned.

  Among these, as the material for the transparent protective film, it is preferable to use a (meth) acrylic resin, a polyethylene terephthalate resin, a polypropylene resin, or a cellulose resin, which is typically a methyl methacrylate resin.

  The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 100% by weight is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

  This methyl methacrylate resin can be usually obtained by polymerizing a monofunctional monomer having methyl methacrylate as a main component in the presence of a radical polymerization initiator and a chain transfer agent. In the polymerization, a small amount of a polyfunctional monomer may be copolymerized.

  Monofunctional monomers that can be copolymerized with methyl methacrylate include, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxy methacrylate. Methacrylic acid esters other than methyl methacrylate such as ethyl; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate Acrylic acid esters such as: 2- (hydroxymethyl) methyl acrylate, 2- (1-hydroxyethyl) methyl acrylate, 2- (hydroxymethyl) ethyl acrylate, and 2- (hydroxymethyl) ) Hydroxyalkyl acrylates such as butyl acrylate; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituted styrenes such as vinyltoluene and α-methylstyrene; Acrylonitrile And unsaturated nitriles such as methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. These copolymerizable monomers may be used alone or in combination of two or more.

  Examples of the polyfunctional monomer that can be copolymerized with methyl methacrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate. , Ethylene glycol such as nonaethylene glycol di (meth) acrylate, and tetradecaethylene glycol di (meth) acrylate, or both oligomers thereof esterified with acrylic acid or methacrylic acid; both propylene glycol or oligomer thereof Terminal hydroxyl groups esterified with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, and butanediol Those obtained by esterifying the hydroxyl group of a dihydric alcohol such as (meth) acrylate with acrylic acid or methacrylic acid; bisphenol A, an alkylene oxide adduct of bisphenol A, or both terminal hydroxyl groups of these halogen-substituted products with acrylic acid or methacrylic acid Esterified with polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid, and those obtained by ring-opening addition of an epoxy group of glycidyl acrylate or glycidyl methacrylate to the terminal hydroxyl groups; Glycidyl acrylate or glycidyl methacrylate for succinic acid, adipic acid, terephthalic acid, phthalic acid, dibasic acids such as these halogen-substituted products, and alkylene oxide adducts thereof Those with an epoxy group is ring-opening addition; allyl (meth) acrylate; aromatic divinyl such divinylbenzene compounds, and the like. Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

  The methyl methacrylate resin may be further modified by a reaction between the copolymerized functional groups. As the reaction, for example, demethanol condensation reaction in a polymer chain between a methyl ester group of methyl acrylate and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate, a carboxyl group of acrylic acid and 2- (hydroxymethyl) acrylic Examples thereof include a dehydration condensation reaction in the polymer chain with a hydroxyl group of methyl acid.

  Such methyl methacrylate resins can be easily obtained as commercial products. For example, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acripet (manufactured by Mitsubishi Rayon Co., Ltd.), Dell Examples include pets (made by Asahi Kasei Co., Ltd.), parapets (made by Kuraray Co., Ltd.), and acrylic viewers (made by Nippon Shokubai Co., Ltd.).

  The polyethylene terephthalate resin means a resin in which 80 mol% or more of repeating units are composed of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. Examples of other dicarboxylic acid components include isophthalic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid, 1,4 -Dicarboxycyclohexane etc. are mentioned.

  Examples of other diol components include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

  These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. Further, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid can be used in combination. Further, as another copolymer component, a dicarboxylic acid component or a diol component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used.

  Polyethylene terephthalate resin can be produced by direct polycondensation of terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as required), dialkyl esters of terephthalic acid and ethylene glycol (and if necessary) A method of transesterification with a dialkyl ester of another dicarboxylic acid or other diol), followed by polycondensation, ethylene glycol ester of terephthalic acid (and other dicarboxylic acids if necessary) (and other if necessary) For example, a polycondensation method in the presence of a catalyst. Furthermore, if necessary, solid-state polymerization can be performed to improve the molecular weight or reduce the low molecular weight components.

  The polypropylene resin refers to a polymer obtained by polymerizing a chain olefin monomer in which 80% by weight or more of repeating units are propylene monomers using a polymerization catalyst. Among these, a propylene homopolymer is preferable. Among the homopolymers of propylene, those having a component soluble in xylene at 20 ° C. (CXS component) of 1% by weight or less are more preferred, and those having a CXS component of 0.5% by weight or less are more preferred. Also preferred is a copolymer comprising propylene as a main component and a comonomer copolymerizable therewith in an amount of 1 to 20% by weight, preferably 3 to 10% by weight.

  When using a propylene copolymer, ethylene, 1-butene, and 1-hexene are preferable as a comonomer copolymerizable with propylene. Especially, since it is comparatively excellent in transparency, what copolymerized ethylene in the ratio of 3 to 10 weight% is preferable. By setting the copolymerization ratio of ethylene to 1% by weight or more, an effect of increasing transparency appears. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin is lowered, and the heat resistance required for the protective film may be impaired.

  Cellulosic resins are those in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp) are substituted with acetyl groups, propionyl groups and / or butyryl groups. Further, it refers to a cellulose organic acid ester or a cellulose mixed organic acid ester. Examples include cellulose acetates, propionate esters, butyrate esters, and mixed esters thereof. Among these, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like are preferable.

  As a method for producing a transparent protective film that adheres to a polarizing film from such a methyl methacrylate-based resin, a polyethylene terephthalate-based resin, a polypropylene-based resin, a cellulose-based resin, or the like, a method corresponding to the resin is appropriately selected. Well, not particularly limited. For example, a solvent-casting method in which a resin dissolved in a solvent is cast onto a metal band or drum, and the solvent is removed by drying to obtain a film. The resin is heated and kneaded above its melting temperature, extruded from a die, and cooled. For example, a melt extrusion method for obtaining a film is employed. In the melt extrusion method, a single layer film can be extruded or a multilayer film can be extruded simultaneously.

  The film used as the protective film can be easily obtained as a commercial product. For example, if it is a methyl methacrylate resin film, for example, under the trade name, Technoloy (manufactured by Sumitomo Chemical Co., Ltd.), acrylite and acryloprene ( As described above, Mitsubishi Rayon Co., Ltd., Delagrass (Asahi Kasei Co., Ltd.), Paragrass and Comograss (manufactured by Kuraray Co., Ltd.), Acryviewer (Nippon Shokubai Co., Ltd.) and the like can be mentioned.

  Examples of the polyethylene terephthalate resin film include Novaclear (manufactured by Mitsubishi Chemical Corporation), Teijin A-PET sheet (manufactured by Teijin Chemicals Ltd.), and the like under trade names.

  For example, FILMAX CPP film (manufactured by FILMAX), Santox (manufactured by Santox Co., Ltd.), Tosero (manufactured by Tosero Co., Ltd.), Toyobo Pyrene Film (manufactured by Toyobo Co., Ltd.). ), Trefan (manufactured by Toray Film Processing Co., Ltd.), Nihon Polyace (manufactured by Nippon Polyace Co., Ltd.), Dazai FC (manufactured by Phutamura Chemical Co., Ltd.), and the like.

  In the case of a cellulose resin film, for example, Fujitac TD (manufactured by Fuji Film Co., Ltd.), Nika Minolta TAC film KC (manufactured by Konica Minolta Opto Co., Ltd.) and the like can be mentioned as trade names.

  Antiglare property (haze) can be imparted to the transparent protective film used in the present invention. Examples of a method for imparting antiglare properties include a method in which inorganic fine particles or organic fine particles are mixed into a raw material resin to form a film, one of which is constituted by a resin in which fine particles are mixed by multilayer extrusion, and the other is fine particles. A method of forming a two-layer film composed of a resin not mixed with a resin, or a method of forming a three-layer film with a resin mixed with particles outside, and mixing inorganic fine particles or organic fine particles on one side of the film with a curable binder resin For example, a method of coating the coating solution and curing the binder resin to provide an antiglare layer is employed.

  Examples of the inorganic fine particles for imparting antiglare properties include silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate, and the like. Examples of the organic fine particles include crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, and polyimide particles.

  It is preferable that the haze value of the transparent protective film provided with the antiglare property is in the range of 6 to 45%. When the haze value of the antiglare protective film is less than 6%, a sufficient antiglare effect may not appear. On the other hand, if the haze value exceeds 45%, the screen of the liquid crystal display device to which this film is applied may become white and the image quality may be deteriorated.

  The haze value can be measured according to JIS K 7136 using a commercially available haze meter, for example, a haze / transmittance meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.). In measuring the haze value, in order to prevent warping of the film, for example, a measurement sample in which the film surface is bonded to a glass substrate using an optically transparent adhesive so that the antiglare property-imparting surface becomes the surface. Is preferably used.

  On the transparent protective film, functional layers such as a conductive layer, a hard coat layer, and a low reflection layer can be further provided. When the antiglare layer is formed, a resin composition having these functions can be selected as the coating liquid.

  The transparent protective film is preferably subjected to saponification treatment, corona treatment, plasma treatment and the like prior to bonding with the polarizing film.

  The thickness of the transparent protective film is usually about 1 to 500 μm, preferably 10 to 200 μm, and more preferably 20 to 100 μm from the viewpoints of strength and handleability. When the thickness is within this range, the polarizing film is mechanically protected, and even when exposed to high temperature and high humidity, the polarizing film does not shrink and stable optical characteristics can be maintained.

[First Adhesive Layer and Second Adhesive Layer]
As a method of laminating the transparent protective film 102 and the first retardation film 103 made of an olefin resin on the polarizing film 101, there is a method of providing and integrating the first and second adhesive layers 106 and 107, respectively. Adopted. Under the present circumstances, 0.1-35 micrometers is preferable and, as for the thickness of an adhesive bond layer, 0.1-15 micrometers is more preferable. If it is this range, a 1st phase difference film which consists of a transparent protective film and an olefin resin laminated | stacked, and a polarizing film do not arise and peeling does not arise, but the adhesive force which does not have a practical problem is obtained.

  As the adhesive layer, an appropriate layer can be appropriately used depending on the type and purpose of the adherend. For example, there are a solvent type adhesive, an emulsion type adhesive, a pressure sensitive adhesive, a rehumidifying adhesive, a polycondensation type adhesive, a solventless type adhesive, a film adhesive, a hot melt type adhesive and the like.

  One preferable adhesive for forming the second adhesive layer that bonds the polarizing film and the first retardation film is a water-based adhesive. As this water-based adhesive, for example, there is an adhesive mainly composed of a polyvinyl alcohol-based resin. A commercially available thing may be used for a water-system adhesive, and what mixed the solvent and the additive in the commercially available adhesive may be used. Examples of commercially available polyvinyl alcohol resins that can be used as water-based adhesives include KL-318 manufactured by Kuraray Co., Ltd.

  The aqueous adhesive can contain a crosslinking agent. As the crosslinking agent, an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt and the like are preferable, and an epoxy compound is particularly preferable. Examples of commercially available cross-linking agents include Glyoxal and Sumires Resin 650 (30), which is an aqueous solution of a water-soluble epoxy compound sold by Sumika Chemtex Co., Ltd.

  Another preferred adhesive is an adhesive made of an epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating.

  When using an adhesive made of such an epoxy resin composition, the adhesive between the transparent protective film and the first retardation film made of an olefin resin and the polarizing film is applied between the films. On the other hand, it can be carried out by irradiating active energy rays or heating to cure a curable epoxy resin contained in the adhesive. Curing of the epoxy resin by irradiation with active energy rays or heating is preferably performed by cationic polymerization of the epoxy resin. In this specification, an epoxy resin means a compound having two or more epoxy groups in the molecule.

  From the viewpoint of weather resistance, refractive index, cationic polymerizability, etc., the epoxy resin contained in the curable epoxy resin composition that is an adhesive is preferably an epoxy resin that does not contain an aromatic ring in the molecule. Examples of such epoxy resins include hydrogenated epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, and the like.

  The hydrogenated epoxy resin is obtained by a method of glycidyl etherifying a nuclear hydrogenated polyhydroxy compound obtained by selectively subjecting a polyhydroxy compound, which is a raw material of an aromatic epoxy resin, to a nuclear hydrogenation reaction under pressure in the presence of a catalyst. Can get. Examples of aromatic epoxy resins include bisphenol-type epoxy resins such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether; phenol novolac epoxy resins, cresol novolac epoxy resins, and hydroxy Examples include novolak-type epoxy resins such as benzaldehyde phenol novolac epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol. Of the hydrogenated epoxy resins, hydrogenated bisphenol A glycidyl ether is preferred.

  The alicyclic epoxy resin means an epoxy resin having one or more epoxy groups bonded to the alicyclic ring in the molecule. The “epoxy group bonded to an alicyclic ring” means a bridged oxygen atom —O— in the structure represented by the following formula. In the following formula, m is an integer of 2 to 5.

A compound in which a group in which one or more hydrogen atoms in (CH ₂ ) _m in the above formula are removed is bonded to another chemical structure can be an alicyclic epoxy resin. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among alicyclic epoxy resins, an epoxy resin having an oxabicyclohexane ring (m = 3 in the above formula) or an oxabicycloheptane ring (m = 4 in the above formula) exhibits excellent adhesion. Therefore, it is preferably used. Although the alicyclic epoxy resin used preferably below is specifically illustrated, it is not limited to these compounds.

  (A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

  (B) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and n represents an integer of 2 to 20).

  (C) Epoxycyclohexyl methyl esters of dicarboxylic acid represented by the following formula (III):

(In the formula, R ⁵ and R ⁶ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).

  (D) Epoxycyclohexyl methyl ethers of polyethylene glycol represented by the following formula (IV):

(In the formula, R ⁷ and R ⁸ independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10).

  (E) Epoxycyclohexyl methyl ethers of alkanediols represented by the following formula (V):

(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 2 to 20).

  (F) Diepoxy trispiro compound represented by the following formula (VI):

(In the formula, R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

  (G) Diepoxy monospiro compound represented by the following formula (VII):

(In the formula, R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

  (H) Vinylcyclohexene diepoxides represented by the following formula (VIII):

(Wherein R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).
(I) Epoxycyclopentyl ethers represented by the following formula (IX):

(Wherein R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

  (J) Diepoxytricyclodecanes represented by the following formula (X):

(Wherein R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).
Among the alicyclic epoxy resins exemplified above, the following alicyclic epoxy resins are commercially available or similar, and are more preferably used because they are relatively easily available.

(A) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [formula (I) In which R ¹ = R ² = H],
(B) 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo [4.1.0] hept-3-yl) methanol Ester compound of [In the formula (I), R ¹ = 4-CH ₃ , R ² = 4-CH ₃ compound],
(C) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [in the formula (II), R ³ = R ⁴ = H, n = 2 Compound],
(D) (7-Oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the formula (III), R ⁵ = R ⁶ = H, p = 4 compound] ,
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in formula (III), R ⁵ = 4-CH ₃ , R ⁶ = 4-CH ₃ , p = 4 compound]
(F) etherified product of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [in the formula (V), R ⁹ = R ¹⁰ = H, r = Compound of 2].

  Moreover, as an aliphatic epoxy resin, the polyglycidyl ether of an aliphatic polyhydric alcohol or its alkylene oxide adduct can be mentioned. More specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene Diglycidyl ether of glycol; Polyether of polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin A glycidyl ether etc. are mentioned.

  The epoxy resin which comprises the adhesive agent which consists of an epoxy-type resin composition may be used individually by 1 type, and may use 2 or more types together. The epoxy equivalent of the epoxy resin used for this composition is 30-3,000 g / equivalent normally, Preferably it exists in the range of 50-1,500 g / equivalent. When the epoxy equivalent is less than 30 g / equivalent, the flexibility of the composite polarizing plate after curing may be reduced, or the adhesive strength may be reduced. On the other hand, if it exceeds 3,000 g / equivalent, the compatibility with other components contained in the adhesive may be lowered.

  In this adhesive, cationic polymerization is preferably used as a curing reaction of the epoxy resin from the viewpoint of reactivity. For that purpose, it is preferable that the curable epoxy resin composition as an adhesive contains a cationic polymerization initiator. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation or heating with active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, etc., and starts an epoxy group polymerization reaction. Regardless of the type of cationic polymerization initiator, it is preferable from the viewpoint of workability that latency is imparted. Hereinafter, a cationic polymerization initiator that generates a cationic species or Lewis acid upon irradiation of active energy rays and initiates a polymerization reaction of an epoxy group is referred to as a “photo cationic polymerization initiator”, and generates a cationic species or a Lewis acid by heat. The cationic polymerization initiator that initiates the polymerization reaction of the epoxy group is referred to as “thermal cationic polymerization initiator”.

  The method of curing the adhesive by irradiation with active energy rays using a cationic photopolymerization initiator enables curing at room temperature, reducing the need to consider the heat resistance of the polarizing film or distortion due to expansion, and transparent protection This is advantageous in that the film and the polarizing film can be favorably bonded. In addition, since the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy resin.

  Although it does not specifically limit as a photocationic polymerization initiator, For example, aromatic diazonium salt; Onium salts, such as an aromatic iodonium salt and an aromatic sulfonium salt; Iron-allene complex etc. can be mentioned.

  Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate. Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis (diphenylsulfonio) diphenylsulfide bis ( Hexafluorophosphate), 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis (hexafluoroantimonate), 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio ] Diphenyl sulfide bis (hexafluorophosphate), 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4 Examples include '-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate, and the like.

  Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) methanide etc. are mentioned.

  Commercially available products of these photocationic polymerization initiators can be easily obtained. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (Nippon Kayaku Co., Ltd. )), "UVI-6990" (manufactured by Union Carbide), "Adekaoptomer SP-150" and "Adekaoptomer SP-170" (manufactured by ADEKA Corporation), "CI-5102", " "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", and "CIP-2064S" (manufactured by Nippon Soda Co., Ltd.), "DPI-101", "DPI-102" , “DPI-103”, “DPI-105”, “MPI-103”, “MPI-105”, “BBI-101”, “BBI-102” , “BBI-103”, “BBI-105”, “TPS-101”, “TPS-102”, “TPS-103”, “TPS-105”, “MDS-103”, “MDS-105”, “ Examples thereof include “DTS-102” and “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), and the like.

  These photocationic polymerization initiators may be used alone or in admixture of two or more. Among these, aromatic sulfonium salts are particularly preferable because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and thus can provide a cured product having excellent curability and good mechanical strength and adhesive strength. Used.

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of epoxy resins, Preferably it is 1 weight part or more, Preferably it is 15 weight part or less. When the blending amount of the cationic photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the epoxy resin, curing becomes insufficient, and mechanical strength and adhesive strength tend to decrease. Moreover, when the compounding quantity of a photocationic polymerization initiator exceeds 20 weight part with respect to 100 weight part of epoxy resins, the ionic substance in hardened | cured material will increase and the hygroscopic property of hardened | cured material will become high, and durability. Performance may be degraded.

  When using a photocationic polymerization initiator, the curable epoxy resin composition that is an adhesive may further contain a photosensitizer as necessary. By using a photosensitizer, the reactivity of cationic polymerization is improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes.

  Specific examples of the photosensitizer include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o -Benzophenone derivatives such as methyl benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2 Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other α, α-diethoxyacetophenone, benzi Ru, fluorenone, xanthone, uranyl compounds, halogen compounds, and the like. These photosensitizers may be used alone or in combination of two or more. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.

  On the other hand, examples of the thermal cationic polymerization initiator include benzylsulfonium salt, thiophenium salt, thioranium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide. These thermal cationic polymerization initiators can be easily obtained as commercial products. For example, “Adeka Opton CP77” and “Adeka Opton CP66” (manufactured by ADEKA Corporation), “CI” are available under the trade names. -2639 "and" CI-2624 "(manufactured by Nippon Soda Co., Ltd.)," Sun-Aid SI-60L "," Sun-Aid SI-80L "and" Sun-Aid SI-100L "(manufactured by Sanshin Chemical Industry Co., Ltd.) Etc.

  The epoxy resin contained in the adhesive may be cured by either photocationic polymerization or thermal cationic polymerization, or may be cured by both photocationic polymerization and thermal cationic polymerization. In the latter case, it is preferable to use a photocationic polymerization initiator and a thermal cationic polymerization initiator in combination.

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

  Oxetanes are compounds having a 4-membered ring ether in the molecule, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3 -Ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, phenol novolac oxetane and the like. These oxetanes can be easily obtained as commercial products. For example, all of these oxetanes are trade names such as “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT-211”. "Aron oxetane OXT-221" and "Aron oxetane OXT-212" (manufactured by Toagosei Co., Ltd.). These oxetanes are usually contained in the curable epoxy resin composition in a proportion of 5 to 95% by weight, preferably 30 to 70% by weight.

  As the polyols, those having no acidic group other than phenolic hydroxyl groups are preferable. For example, polyol compounds having no functional groups other than hydroxyl groups, polyester polyol compounds, polycaprolactone polyol compounds, polyol compounds having phenolic hydroxyl groups, polycarbonates A polyol etc. can be mentioned. The molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and preferably 1,000 or less. These polyols are usually contained in the curable epoxy resin composition in a proportion of 50% by weight or less, preferably 30% by weight or less.

  Furthermore, in the curable epoxy resin composition, other additives such as an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, and a thermoplastic resin are used as long as the effects of the present invention are not impaired. , Fillers, flow regulators, plasticizers, antifoaming agents, and the like can be blended. Examples of the ion trapping agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based and mixed inorganic compounds. Examples of the antioxidant include hinders. Examples thereof include dophenol antioxidants.

  One or both of the adhesive surfaces of the polarizing film and the transparent protective film, and the adhesive surface of the polarizing film and the first retardation film are adhesives comprising the curable epoxy resin composition containing the epoxy resin as described above. After coating on one or both of the surfaces, the uncoated adhesive layer is cured by applying the active energy ray or heating by pasting on the coated surface of the adhesive and transparent protection. The film can be bonded to the polarizing film, and the first retardation film can be bonded to the polarizing film via an adhesive layer composed of a cured product layer of a curable epoxy resin composition. As an adhesive coating method, for example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater are adopted.

  The adhesive containing an epoxy resin used for bonding the transparent protective film 102 and the first retardation film 103 made of an olefin resin to the polarizing film 101 is basically free of a solvent component. Although it can be used as a solvent-type adhesive, each coating method has an optimum viscosity range, and therefore a solvent may be included for viscosity adjustment. It is preferable to use a solvent that dissolves the epoxy resin composition well without degrading the optical performance of the polarizing film. For example, hydrocarbons represented by toluene, esters represented by ethyl acetate, and the like. And organic solvents such as

When the adhesive is cured by irradiation with active energy rays, the light source used is not particularly limited. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical having a light emission distribution at a wavelength of 400 nm or less. A lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, etc. are mentioned. The light irradiation intensity to the curable epoxy resin composition may vary depending on the composition, but the irradiation intensity in the wavelength region effective for activating the photocationic polymerization initiator is 0.1 to 100 mW / cm ^2. Is preferred. When the light irradiation intensity to the curable epoxy resin composition is less than 0.1 mW / cm ² , the reaction time becomes too long, and when it exceeds 100 mW / cm ² , the heat radiated from the lamp and the curable epoxy resin composition The heat generated during polymerization of the product may cause yellowing of the curable epoxy resin composition or deterioration of the polarizing film. The light irradiation time to the curable epoxy resin composition is controlled for each composition and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 5. It is preferably set to be 000 mJ / cm ² . When the integrated light quantity to the curable epoxy resin composition is less than 10 mJ / cm ² , the generation of active species derived from the photocationic polymerization initiator is not sufficient, and the adhesive may be insufficiently cured. On the other hand, if the integrated light quantity exceeds 5,000 mJ / cm ² , the irradiation time becomes very long, which may be disadvantageous for improving productivity.

  When the adhesive is cured by heat, it can be heated by a generally known method, and the conditions are not particularly limited, but is usually a thermal cationic polymerization initiator compounded in the curable epoxy resin composition. Is heated at a temperature equal to or higher than the temperature at which the cation species and Lewis acid are generated. Specifically, the heating temperature is, for example, about 50 to 200 ° C.

  Whether cured by irradiation with active energy rays or heating, the polarization degree, transmittance and hue of the polarizing film, transparency and retardation characteristics of the first retardation film comprising the transparent protective film and the olefin resin In addition, it is preferable to cure within a range in which various functions of the polarizing plate do not deteriorate.

[Second retardation film]
In the second retardation film 105, the core layer 31 is made of a styrene resin, and the skin layer 32 made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces thereof.

  The styrenic resin constituting the core layer 31 can be a homopolymer of styrene or a derivative thereof, or can be a binary or higher copolymer of styrene or a derivative thereof and another copolymerizable monomer. There can also be. Here, the styrene derivative is a compound in which another group is bonded to styrene, such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, o-ethylstyrene, Alkyl styrene such as p-ethyl styrene, hydroxy styrene, tert-butoxy styrene, vinyl benzoic acid, o-chloro styrene, p-chloro styrene, benzene nucleus of styrene, hydroxyl group, alkoxy group, carboxyl group, halogen Substituted styrene etc. in which etc. were introduced are mentioned. A terpolymer as disclosed in Patent Document 4 and Patent Document 5 can also be used. The styrene resin is preferably a copolymer of styrene or a styrene derivative and at least one monomer selected from acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene. The styrenic resin of the core layer is preferably composed of a heat-resistant one, and generally its Tg is 100 ° C. or higher. A more preferable Tg of the styrene resin is 120 ° C. or more.

  The core layer 31 made of styrene resin is desirably set so that its thickness is 10 to 100 μm. If the thickness is less than 10 μm, a sufficient retardation value may not easily be exhibited by stretching. On the other hand, when the thickness exceeds 100 μm, the impact strength of the film tends to be weak, and the retardation change due to external stress tends to increase, and white spots etc. are likely to occur when applied to a liquid crystal display device, Display performance is likely to deteriorate.

  The skin layers 32 disposed on both surfaces of the core layer 31 made of the styrene resin are made of a (meth) acrylic resin composition in which rubber particles are blended with a (meth) acrylic resin. Here, examples of the (meth) acrylic resin include a homopolymer of a methacrylic acid alkyl ester or an acrylic acid alkyl ester, a copolymer of a methacrylic acid alkyl ester and an acrylic acid alkyl ester, and the like. Specific examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, and propyl methacrylate. Specific examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, and propyl acrylate. . As such a (meth) acrylic resin, a commercially available (meth) acrylic resin can be used. Some (meth) acrylic resins are called impact-resistant (meth) acrylic resins, and high heat-resistant (meth) acrylic resins having a glutaric anhydride structure or lactone ring structure in the main chain Also called.

  The rubber particles blended in the (meth) acrylic resin are preferably acrylic. Acrylic rubber particles are particles having rubber elasticity obtained by polymerizing in the presence of a polyfunctional monomer mainly composed of an alkyl acrylate ester such as butyl acrylate or 2-ethylhexyl acrylate. Such rubber elastic particles may be formed as a single layer, or may be a multilayer structure having at least one rubber elastic layer. As the acrylic rubber particles having a multilayer structure, particles having rubber elasticity as described above are used as cores, and the periphery thereof is covered with a hard alkyl methacrylate ester polymer, or a hard alkyl methacrylate ester polymer. The core is covered with an acrylic polymer having rubber elasticity as described above, and the hard core is covered with an acrylic polymer having rubber elasticity, and the surroundings are hard methacrylic acid. Examples thereof include those covered with an alkyl ester polymer. These rubber particles generally have an average diameter of particles formed of an elastic layer in the range of about 50 to 400 nm.

  The content of the rubber particles in the (meth) acrylic resin composition constituting the skin layer 32 is usually about 5 to 50 parts by weight per 100 parts by weight of the (meth) acrylic resin. Since (meth) acrylic resin and acrylic rubber particles are commercially available in a state where they are mixed, commercially available products thereof can be used. Examples of commercially available products of (meth) acrylic resins containing acrylic rubber particles include “HT55X” and “Technoloy (registered trademark) S001” sold by Sumitomo Chemical Co., Ltd. Such a (meth) acrylic resin composition generally has a Tg of 160 ° C. or lower, but a preferable Tg is 120 ° C. or lower, and further 110 ° C. or lower.

  The skin layer 32 made of a (meth) acrylic resin composition containing rubber particles, preferably acrylic rubber particles, is desirably made to have a thickness of 10 to 100 μm. If the thickness is to be less than 10 μm, film formation tends to be difficult. On the other hand, when the thickness exceeds 100 μm, the retardation of the (meth) acrylic resin layer tends to be ignorable.

  As described above, in the second retardation film 105 used in the present invention, the core layer 31 made of a styrene resin preferably has a Tg of 120 ° C. or higher, while rubber particles are blended (meta). The skin layer 32 made of the acrylic resin composition preferably has a Tg of 120 ° C. or lower, more preferably 110 ° C. or lower. It is preferable that the core layers 31 made of a styrene resin have a higher Tg than the skin layer 32 made of a (meth) acrylic resin composition containing rubber particles. .

  In order to produce the second retardation film 105 used in the present invention, for example, a styrene resin and a (meth) acrylic resin composition containing rubber particles may be coextruded and then stretched. . In addition, after each single-layer film is produced, heat fusion can be performed by heat lamination and the film can be stretched.

  The second retardation film 105 has a three-layer structure in which skin layers 32 made of a (meth) acrylic resin composition containing rubber particles are formed on both surfaces of a core layer 31 made of a styrene resin. Is done. In this three-layer structure, the skin layers 32 arranged on both sides are usually set to substantially the same thickness. Thus, by setting it as a 3 layer structure, the skin layer 32 which consists of a (meth) acrylic-type resin composition with which the rubber particle was mix | blended works as a protective layer, and becomes excellent in mechanical strength and chemical resistance.

  The second retardation film 105 configured as described above is given in-plane retardation by stretching. Stretching can be performed by known longitudinal uniaxial stretching, tenter lateral uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like, and may be performed so as to obtain a desired retardation value.

  The second retardation film 105 used in the present invention has an in-plane retardation Re of 20 to 120 nm, and an Nz coefficient defined by the formula (5) exceeds −2 and is less than −0.5. It preferably has refractive index anisotropy.

  When laminating the first retardation film 103 and the second retardation film 105, the change in angle between the orientation angles of the first retardation film 103 and the second retardation film 105 is 10 cm. It is preferable that the angle be 0.4 ° or less. When the change of the angle formed by the orientation angle exceeds 0.4 °, the polarization state locally changes steeply, so that it is observed as color unevenness when mounted on a liquid crystal display device. Here, the orientation angle refers to the orientation in which the refractive index at each part of each film is maximum.

  In a stretched film, the axis with the maximum refractive index in the plane is generally called the slow axis, but if you look closely, the axis may change slightly in each part. Is done. The orientation angle can be measured using a commercially available phase difference meter or inspection device, for example, a retardation film / optical material inspection device RETS manufactured by Otsuka Electronics Co., Ltd. as shown in the examples described later. In order to reduce the change (shift) between the orientation angles of the first retardation film 103 and the second retardation film 105 as described above, for example, the first retardation film 103 and the first retardation film 103 For each of the two retardation films 105, it is preferable to use a film having a small misalignment angle.

[Adhesive]
The second retardation film 105 having a structure in which the first retardation film 103 made of the olefin resin and the core layer 31 made of styrene resin are sandwiched between the skin layers 32 and 32 made of acrylic resin, Laminated via the adhesive 104. The thickness of the pressure-sensitive adhesive layer 104 is usually about 5 to 100 μm, preferably 5 to 40 μm. If the pressure-sensitive adhesive layer is too thin, the tackiness is lowered, and if it is too thick, problems such as the pressure-sensitive adhesive protruding easily occur. As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer 104, a known one can be used. Usually, an acrylic resin, a styrene resin, a silicone resin or the like is used as a base resin, and an isocyanate compound, an epoxy compound, It consists of a composition in which a crosslinking agent such as an aziridine compound is added and, if necessary, a silane coupling agent or the like is added.

[Liquid Crystal Display]
The composite polarizing plate 100 configured as described above can be bonded to a liquid crystal cell by disposing the pressure-sensitive adhesive layer 108 on the outside of the second retardation film 105. Further, a separator 109 is usually bonded to the outside of the pressure-sensitive adhesive layer 108 to temporarily protect the pressure-sensitive adhesive layer 108 until use. The composite polarizing plate 100 is laminated on at least one side of the liquid crystal cell to constitute a liquid crystal display device. When applied to a liquid crystal display device, the separator 109 is peeled off and then bonded to the liquid crystal cell with the adhesive layer 108. The composite polarizing plate can be disposed on both sides of the liquid crystal cell, the composite polarizing plate can be disposed on one side of the liquid crystal cell, and another polarizing film can be disposed on the other side. In pasting to a liquid crystal cell, it arrange | positions so that the phase difference film side may face a liquid crystal cell.

  The liquid crystal display device of the present invention may have a configuration in which the composite polarizing plate of the present invention is disposed on both surfaces of the liquid crystal cell, or may have a configuration in which the composite polarizing plate of the present invention is disposed on one side of the liquid crystal cell. . In the latter case, another polarizing plate may be disposed on the side where the composite polarizing plate of the present invention is not disposed. The liquid crystal display device having such a configuration is particularly effective when the liquid crystal cell is in a transverse electric field mode.

  In the liquid crystal display device of the present invention, when the composite polarizing plate of the present invention is disposed on one surface of the liquid crystal cell, the in-plane retardation Re is 10 nm or less and the thickness direction retardation Rth is on the other surface. It is preferable to dispose a polarizing plate having a transparent protective film having an absolute value of 15 nm or less on the liquid crystal cell side. The protective film on the liquid crystal cell side of the polarizing plate more preferably has Re of 5 nm or less and an absolute value of Rth of 10 nm or less.

  Examples of materials used for the transparent protective film satisfying the requirement that the in-plane retardation Re is 10 nm or less and the absolute value of the thickness direction retardation Rth is 15 nm or less include cellulose resins, cyclic olefin resins, and (meth) acrylic. Resin, polyethylene terephthalate resin, polypropylene resin and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “part” and “%” representing the amount used or content are based on weight unless otherwise specified. Further, the thickness, in-plane and thickness direction retardation, and Nz coefficient of the film were measured by the following methods.

[Method for measuring thickness]
The thickness of the film was measured using a digital micrometer MH-15M manufactured by Nikon Corporation.

[In-plane retardation, thickness direction retardation and Nz coefficient measurement method]
In-plane retardation Re, thickness direction retardation Rth and Nz coefficient were measured with a light of wavelength 590 nm at 23 ° C. using a phase difference meter KOBRA-21ADH based on the parallel Nicol rotation method manufactured by Oji Scientific Instruments. did.

  First, three layers in which a skin layer made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer made of an adhesive, an adhesive, and a styrene resin used in Examples and Comparative Examples The example which manufactured the 2nd phase difference film which consists of a structure is shown.

[Preparation of water-based adhesive]
3 parts of carboxyl group-modified polyvinyl alcohol [KL-318 manufactured by Kuraray Co., Ltd.] is dissolved in 100 parts of water, and a polyamide epoxy additive [Sumika Chemtex Co., Ltd.] which is a water-soluble epoxy compound is dissolved in the aqueous solution. 1.5 parts of an aqueous solution having a solid content concentration of 30%] was added to obtain an aqueous adhesive.

[Preparation of an adhesive comprising a curable epoxy resin composition]
100 parts of bis (3,4-epoxycyclohexylmethyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A, and 4,4′-bis (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate as a photocationic polymerization initiator ) After 2.2 parts were mixed, defoaming was performed to obtain an adhesive made of a curable epoxy resin composition. The cationic photopolymerization initiator was blended as a 50% propylene carbonate solution.

[Preparation of acrylic adhesive]
A release treatment surface of a polyethylene terephthalate film (separator) with a thickness of 38 μm obtained by releasing an organic solvent solution in which a copolymer of butyl acrylate and acrylic acid is mixed with a urethane acrylate oligomer and an isocyanate crosslinking agent. Then, it was coated with a die coater so that the thickness after drying was 25 μm and dried to obtain an acrylic pressure-sensitive adhesive.

[Production of second retardation film having a three-layer structure]
(Phase difference film A)
Styrene-maleic anhydride copolymer resin (“Dylark (registered trademark) D332” manufactured by Nova Chemical Co., Ltd., Tg = 131 ° C.) is used as a core layer, and about 20% of acrylic rubber particles having an average particle diameter of 200 nm are blended. A methacrylic resin (“Technoloy (registered trademark) S001” manufactured by Sumitomo Chemical Co., Ltd., Tg = 105 ° C.) is used as a skin layer, and three-layer coextrusion is performed, and a skin layer is formed on both sides of the core layer. A three-layer film was obtained. This resin three-layer film was stretched to produce a retardation film with Re = 47.3 nm and Nz coefficient = −1.06. This is designated as retardation film A.

(Phase difference film B)
The same resin three-layer film as used for the production of the retardation film A described above was stretched to produce a retardation film with Re = 47.3 nm and Nz coefficient = −0.98. This is designated as retardation film B.

(Phase difference film C)
The same resin three-layer film used for the production of the retardation film A described above was stretched to produce a retardation film with Re = 55.0 nm and Nz coefficient = −1.1. This is designated as retardation film C.

[Example 1]
(A) Preparation of composite polarizing plate A polyvinyl alcohol film having a thickness of 75 μm made of polyvinyl alcohol having an average degree of polymerization of about 2,400 and a degree of saponification of 99.9 mol% or more is uniaxially stretched about 5 times by a dry method, Further, while maintaining tension, the sample was immersed in pure water at 60 ° C. for 1 minute, and then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, it was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol.

  On one side of this polarizing film, a 80 μm thick triacetyl cellulose film having a saponified surface was bonded as a transparent protective film, and on the other side as a first retardation film, Japan. A film made of a cyclic olefin-based resin having a thickness of 38.6 μm obtained from ZEON Co., Ltd., having Re = 74.2 nm and Nz coefficient = 1.41. The polarizing plate was produced by laminating so that the fast axis of the phase difference film was parallel. For the bonding, the above-described aqueous adhesive was used, and after the bonding, the transparent protective film and the first retardation film were adhered to the polarizing film by drying at 80 ° C. for 5 minutes. The obtained polarizing plate was then cured at 40 ° C. for 168 hours.

  On the first retardation film side of the polarizing plate thus obtained, as the second retardation film, the retardation film A shown above is used with an acrylic adhesive and the absorption axis of the polarizing film and the second retardation film A. The retardation film was bonded so that the fast axes were parallel to produce a composite polarizing plate.

(B) Production and evaluation of liquid crystal display device The backlight is removed from the liquid crystal display device [VIERA (model number: TH-37LZ85) manufactured by Panasonic Corporation] including an IPS mode liquid crystal cell, and further on the backlight side of the liquid crystal cell. The placed polarizing plate was removed and the glass surface was washed. Next, on the backlight side of the liquid crystal cell, the composite polarizing plate produced in (A) is placed in the second position so that the absorption axis thereof is the same as the absorption axis of the polarizing plate originally disposed. A liquid crystal panel was prepared by adhering via an acrylic pressure-sensitive adhesive so that the phase difference film was on the liquid crystal cell side. Finally, the liquid crystal display device was assembled by re-installing the backlight once removed.

  FIG. 2 shows a contrast ratio distribution diagram of the liquid crystal display device measured 30 minutes after the backlight was turned on using a liquid crystal viewing angle measuring device “EZ Contrast 88XL” manufactured by ELDIM. In the figure, the numbers on the horizontal axis represent polar angles, the numbers on the circumference represent azimuth angles, and the distribution of contrast ratio is represented by black and white shades corresponding to the contrast ratio of the scale shown on the right (Fig. The same applies to 3-7. At a position with an azimuth angle of 135 ° and a polar angle of 60 ° (circles in the figure), a contrast ratio of 192 was shown. Here, the contrast ratio is a ratio of luminance in the white display state / luminance in the black display state. Further, the azimuth angle is a value in which the right direction on the screen is 0 ° and the counterclockwise direction is positive, and the polar angle is an inclination from the normal direction of the screen.

[Example 2]
(A) Preparation of composite polarizing plate In (A) of Example 1, the first retardation film was a film made of a cyclic olefin resin having a thickness of 29.8 μm obtained from Nippon Zeon Co., Ltd. From the (meth) acrylic resin composition containing the rubber particles on both sides of the core layer made of styrene resin, the second retardation film was changed to one having Re = 79.2 nm and Nz coefficient = 1.21. A composite polarizing plate was produced in the same manner as in the above-described retardation film B having a three-layer structure in which a skin layer was formed.

(B) Production and Evaluation of Liquid Crystal Display Device A liquid crystal display device was produced in the same manner as in (B) of Example 1 except that the composite polarizing plate obtained here was used. FIG. 3 is a distribution diagram of contrast ratios measured for this liquid crystal display device in the same manner as in Example 1 (B). At a position with an azimuth angle of 135 ° and a polar angle of 60 ° (circles in the figure), a contrast ratio of 195 was shown.

[Example 3]
(A) Preparation of composite polarizing plate and polarizing plate In the same manner as in (A) of Example 2, a transparent protective film made of triacetylcellulose was bonded to one side of the polarizing film, and Re = 79. A skin made of a (meth) acrylic resin composition containing rubber particles on both sides of a first retardation film made of a cyclic olefin resin having a 2 nm Nz coefficient = 1.21 and a core layer made of a styrene resin A composite polarizing plate in which a retardation film B having a three-layer structure in which layers were formed was laminated was prepared.

  On the other hand, a 80 μm-thick triacetyl cellulose film having a surface saponified was bonded to one side of a polarizing film produced according to the method shown in the first half of Example 1 (A). A transparent protective film [KC4UEW manufactured by Konica Minolta Opto Co., Ltd.] with Re = 0.7 nm and Rth = −0.1 nm is bonded to both sides, and is made of triacetyl cellulose having a thickness of 40 μm. A polarizing plate on which a transparent protective film made of triacetyl cellulose was laminated was prepared. For the bonding, the above-described aqueous adhesives were used, and after the bonding, the transparent protective films on both sides were bonded to the polarizing films by drying at 80 ° C. for 5 minutes.

(B) Production and Evaluation of Liquid Crystal Display Device Remove the backlight from the liquid crystal display device including the same IPS mode liquid crystal cell as used in (B) of Example 1, and further remove the polarizing plates on both sides of the liquid crystal cell. The glass surface was washed. Next, on the backlight side of the liquid crystal cell, the composite polarizing plate shown in the first half of the above (A) is placed on the viewing side of the liquid crystal cell so that the second retardation film is on the liquid crystal cell side. The polarizing plate shown in the latter half of A) is such that the 40 μm-thick triacetyl cellulose film is on the liquid crystal cell side, and the respective absorption axes are the same as the absorption axes of the polarizing plates originally arranged. A liquid crystal panel was prepared by bonding via an acrylic pressure-sensitive adhesive. Finally, the liquid crystal display device was assembled by re-installing the backlight once removed.

  FIG. 4 shows a distribution diagram of the contrast ratio measured in the same manner as in Example 1 (B) for this liquid crystal display device. At a position with an azimuth angle of 135 ° and a polar angle of 60 ° (circles in the figure), a contrast ratio of 195 was shown.

[Example 4]
(A) Preparation of composite polarizing plate and polarizing plate In the same manner as in (A) of Example 2, a transparent protective film made of triacetylcellulose was bonded to one side of the polarizing film, and Re = 79. A skin made of a (meth) acrylic resin composition containing rubber particles on both sides of a first retardation film made of a cyclic olefin resin having a 2 nm Nz coefficient = 1.21 and a core layer made of a styrene resin A composite polarizing plate in which a retardation film B having a three-layer structure in which layers were formed was laminated was prepared.

  On the other hand, a 80 μm-thick triacetyl cellulose film having a surface saponified was bonded to one side of a polarizing film produced according to the method shown in the first half of Example 1 (A). A transparent protective film [obtained from Nippon Zeon Co., Ltd.] of Re = 2.1 nm and Rth = 2.8 nm is bonded to the surface of the transparent protective film. Was produced. For the pasting, each of the aqueous adhesives shown above was used, and after the pasting, the transparent protective films on both sides were adhered to the polarizing film by drying at 80 ° C. for 5 minutes, and then cured at 40 ° C. for 168 hours. did.

(B) Production and Evaluation of Liquid Crystal Display Device Remove the backlight from the liquid crystal display device including the same IPS mode liquid crystal cell as used in (B) of Example 1, and further remove the polarizing plates on both sides of the liquid crystal cell. The glass surface was washed. Next, on the backlight side of the liquid crystal cell, the composite polarizing plate shown in the first half of the above (A) is placed on the viewing side of the liquid crystal cell so that the second retardation film is on the liquid crystal cell side. The polarizing plate shown in the latter half of A) is made the same as the absorption axis of the polarizing plate in which each protective axis was originally arranged so that the protective film made of a cyclic olefin resin having a thickness of 40 μm is on the liquid crystal cell side. In this way, a liquid crystal panel was produced by bonding via an acrylic pressure-sensitive adhesive. Finally, the liquid crystal display device was assembled by re-installing the backlight once removed.

  FIG. 5 shows a contrast ratio distribution diagram measured in the same manner as in Example 1 (B) for this liquid crystal display device. At a position with an azimuth angle of 135 ° and a polar angle of 60 ° (circles in the figure), a contrast ratio of 195 was shown.

[Comparative Example 1]
(A) Production of polarizing plate A polarizing film produced according to the method shown in the first half of Example 1 (A) was attached to one surface of a triacetyl cellulose film having a thickness of 80 μm and subjected to saponification treatment. On the other side, a transparent protective film [KC4UEW manufactured by Konica Minolta Opto Co., Ltd.] made of triacetyl cellulose having a thickness of 40 μm and having Re = 0.7 nm and Rth = −0.1 nm is bonded. And the polarizing plate by which the transparent protective film which consists of triacetylcellulose was laminated | stacked on both surfaces was produced. For the bonding, the above-described aqueous adhesives were used, and after the bonding, the transparent protective films on both sides were bonded to the polarizing films by drying at 80 ° C. for 5 minutes.

(B) Production and Evaluation of Liquid Crystal Display Device A liquid crystal display device was produced in the same manner as in (B) of Example 1 except that the polarizing plate produced here was used. This polarizing plate was adhered to the liquid crystal cell on the side of the 40 μm thick triacetyl cellulose film. FIG. 6 shows a contrast ratio distribution diagram measured in the same manner as in Example 1 (B) for this liquid crystal display device. At a position with an azimuth angle of 135 ° and a polar angle of 60 ° (circles in the figure), a contrast ratio of 26 was shown.

[Example 5]
(A) Production of composite polarizing plate In (A) of Example 1, the first retardation film was a film made of cyclic olefin resin having a thickness of 35.8 μm obtained from Nippon Zeon Co., Ltd. From the (meth) acrylic resin composition containing the rubber particles on both sides of the core layer made of styrene resin, the second retardation film was changed to one having Re = 76.2 nm and Nz coefficient = 1.37. A composite polarizing plate was prepared in the same manner except that the retardation film C was changed to the above-described retardation film C having a three-layer structure in which a skin layer was formed.

(B) Production and Evaluation of Liquid Crystal Display Device A liquid crystal display device was produced in the same manner as in (B) of Example 1 except that the composite polarizing plate obtained here was used. FIG. 7 is a distribution diagram of contrast ratios measured for this liquid crystal display device in the same manner as in Example 1 (B). At a azimuth angle of 135 ° and a polar angle of 60 °, a contrast ratio of 326 was shown.

  In this liquid crystal display device, local color unevenness was observed in the display. Therefore, the used composite polarizing plate was peeled off from the liquid crystal panel, cut out in the screen width direction centering on the portion where the local color unevenness was observed, and from the second retardation film having a three-layer structure and the cyclic olefin resin. The first retardation film is peeled off, and the orientation angle of the corresponding part in each bonded state is determined using the retardation film / optical material inspection apparatus RETS manufactured by Otsuka Electronics Co., Ltd. The measurement was performed over 80 cm, and the angle formed by the orientation angles at each part (difference between one orientation angle and the other orientation angle) was calculated. The result is shown in FIG. The change between 10 cm in the angle formed by the orientation angles of the two retardation films used here was 0.43 ° at the maximum.

(C) Production and Evaluation of Another Composite Polarizing Plate and Liquid Crystal Display Device On the other hand, although the same grade as that used as the first retardation film in (A) above, another lot of film [Nippon Zeon Corporation The film is made of a cyclic olefin resin having a thickness of 35.8 μm obtained from the above, and has a Re = 76.2 nm, Nz coefficient = 1.37], and the others are combined in the same manner as in the above (A). A polarizing plate was produced, and a liquid crystal display device was assembled using the polarizing plate in the same manner as in the above (B). The distribution of the contrast ratio of this liquid crystal display device is the same as that in FIG. 7 and the contrast ratio at the azimuth angle of 135 ° and the polar angle of 60 ° was 326, but no local color unevenness was observed in the display. .

  The composite polarizing plate used here was peeled off from the liquid crystal panel, and the same part as the orientation angle measured above was cut out in the screen width direction, and the second retardation film consisting of a three-layer structure and a second comprising a cyclic olefin resin. 1 is peeled off, and the orientation angle of the corresponding portion in each bonded state is set to 80 cm in the width direction of the screen using a retardation film / optical material inspection apparatus RETS manufactured by Otsuka Electronics Co., Ltd. Measurements were made across the board, and the angle formed by the orientation angles at each site (difference between one orientation angle and the other orientation angle) was calculated. The result is shown in FIG. The maximum change between 10 cm in the angle formed by the orientation angles of the two retardation films used here was 0.27 °.

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

  DESCRIPTION OF SYMBOLS 100 Composite polarizing plate, 101 Polarizing film, 102 Transparent protective film, 103 1st phase difference film, 104 Adhesive layer, 105 2nd phase difference film, 106 1st adhesive layer, 107 2nd adhesive layer , 108 pressure-sensitive adhesive layer, 109 separator, 31 core layer, 32 skin layer.

Claims (8)

A transparent protective film is laminated on one surface of the polarizing film via a first adhesive layer, and a first film comprising a stretched film of an olefin resin on the other surface of the polarizing film via a second adhesive layer. A retardation film is laminated,
Furthermore, a skin layer made of a (meth) acrylic resin composition containing rubber particles was formed on both surfaces of a core layer made of styrene resin via an adhesive layer on the outside of the first retardation film. A second retardation film made of a stretched film having a three-layer structure is laminated ,
The first retardation film has an in-plane retardation is 30 to 150 nm, the in-plane slow axis direction, the in-plane fast axis direction and the refractive index in the thickness direction, respectively n _x, n _y and n _z when the _{formula: (n x -n z) /} (n x -n y) exceeds the Nz coefficient 1 that is defined by having less than 2 of the refractive index anisotropy,
The second retardation film has an in-plane retardation of 20 to 120 nm, an Nz coefficient as defined above exceeding −2, and a refractive index anisotropy of less than −0.5,
The first retardation film and the second retardation film are laminated so that the change in angle between the orientation angles of the first retardation film and the second retardation film is 0.4 ° or less between 10 cm. Polarizer. The composite polarizing plate according to claim 1, wherein the olefin resin is a cyclic olefin resin containing a structural unit derived from an alicyclic olefin. The second retardation film includes a core layer made of the styrene resin having a glass transition temperature of 120 ° C. or higher, and a skin layer made of the (meth) acrylic resin composition having a glass transition temperature of 120 ° C. or lower. The composite polarizing plate of Claim 1 or 2 comprised by these. The second adhesive layer, the composite polarizer according to any one of claims 1 to 3 comprising a water-based adhesive containing a polyvinyl alcohol resin and an epoxy compound. The composite according to any one of claims 1 to 3 , wherein the second adhesive layer is formed of a cured product layer of an epoxy resin composition containing an epoxy resin that is cured by irradiation with an activation energy ray or heating. Polarizer. The composite polarizing plate according to claim 5 , wherein the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule. On at least one surface of the IPS mode liquid crystal cell, an IPS mode liquid crystal display device in which is arranged a composite polarizing plate according to any one of claims 1-6. The composite polarizing plate according to any one of claims 1 to 6 is disposed on one surface of the IPS mode liquid crystal cell, and the in-plane retardation is 10 nm or less on the other surface. The IPS mode liquid crystal display device according to claim 7 , wherein a polarizing plate having a transparent protective film having a value of 15 nm or less on the liquid crystal cell side is disposed.