CN101813798A - Composite polarizing plate and IPS mode liquid crystal display device using same - Google Patents

Abstract

The present invention provides a composite polarizing plate in which a transparent protective film is laminated on one surface of a polarizing film via a first adhesive layer, and an olefin-based resin-containing film is laminated on the other surface of the polarizing film via a second adhesive layer. The first phase difference film, and further, laminated on the outside of the first phase difference film through the adhesive layer, the (meth)acrylic resin containing rubber particles is formed on both sides of the core layer containing styrene resin. The compound polarizing plate of the second retardation film of the 3-layer structure of the skin layer formed of the composition. By arranging this composite polarizing plate on at least one surface of an IPS mode liquid crystal cell, an IPS mode liquid crystal display device can be manufactured.

Description

Composite polarizing plate and IPS mode liquid crystal display device using same

technical field

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 composite polarizing plate.

Background technique

Liquid crystal display devices have characteristics such as low power consumption, low-voltage operation, light weight, and thin profile, and are used in various display devices. A liquid crystal display device includes a liquid crystal cell, a polarizing film, a retardation film, a light collecting sheet, a diffusing film, a light guide plate, a light reflecting sheet, and other materials. Therefore, improvements such as productivity enhancement, weight reduction, lightness, and the like are being actively pursued by reducing the number of constituting films or reducing the thickness of the film or sheet.

Furthermore, liquid crystal display devices are required to be products that can withstand severe durability conditions. For example, for a liquid crystal display device for a car navigation system, the temperature and humidity may become very high when it is placed in a car. In addition, for monitors such as mobile phones and mobile terminals, monitors for televisions, and computers In other words, depending on their use environment and installation location, there may be cases where they are exposed to severe changes in temperature and humidity. Therefore, the performance of products that can withstand use under such severe conditions is required.

A polarizing plate generally has a structure in which a transparent protective film is laminated on both surfaces or one surface of a polarizing film containing a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and aligned.

The polarizing film can be produced by longitudinally uniaxially stretching a polyvinyl alcohol-based resin film and dyeing with a dichroic dye, followed by boric acid treatment to cause a crosslinking reaction, followed by washing with water and drying. As the dichroic dye, iodine or a dichroic organic dye can be used. A protective film is laminated on both surfaces or one surface of the polarizing film obtained in this way to form a polarizing film, which can be assembled in a liquid crystal display device and used. As the protective film, a cellulose acetate-based resin film represented by cellulose triacetate is often used, and its thickness is usually about 30 to 120 μm. In addition, for lamination of protective films, adhesives composed of aqueous solutions of polyvinyl alcohol-based resins are often used.

When a polarizing plate composed of such members is used for a long period of time under humid heat conditions, the polarization performance may be lowered, or the protective film and the polarizing film may be easily peeled off.

Therefore, attempts have been made to constitute at least one of the protective films with resins other than cellulose acetate-based resins. For example, JPH08-43812-A describes a technique in which at least one of the protective films is formed of a thermoplastic norbornene-based resin that functions as a retardation film in a polarizing film in which protective films are laminated on both surfaces. In addition, JPH09-325216-A describes a technique in which at least one of the protective layers of a polarizing film is constituted by a birefringent film.

On the other hand, in styrene-based resin films, since the polarizability of the side chain is larger than that of the main chain of the styrene-based resin (sometimes the polarization is negative), it is being studied as the polarizability of the thickness direction. A negative retardation film with a large refractive index. However, there are still problems in heat resistance, mechanical strength, and chemical resistance in styrene-based resin films, and practical use has not yet been achieved.

的关系、且(n_x-n_z)/(n_x-n_y)所定义的N_z系数约为0(零)的膜。Here, the negative retardation film having a large refractive index in the thickness direction means that the refractive index in the direction of the maximum refractive index (slow axis direction) in the plane is n x , and the refractive index in the direction perpendicular to it in the plane (the slow axis direction) is n _x . When the refractive index in the phase axis direction) is set to _ny and the refractive index in the thickness direction is set to _nz , there is

, and the N _z coefficient defined by (n _x -n _z )/(n _{x -ny} ) is about 0 (zero).

The heat resistance of styrene-based resins is known to be improved by copolymerizing them with monomers that form resins with a high glass transition temperature (hereinafter, sometimes abbreviated as Tg), such as norbornene and maleic anhydride. , but the mechanical strength and chemical resistance are insufficient.

Many techniques of laminating other resin layers on a styrene-based film by copolymerizing styrene with other monomers have also been proposed. For example, in JP2002-517583-A, it is described that an essentially random copolymer formed of an aromatic vinyl monomer represented by styrene and an α-olefin is formed into a film. Inspiration for multilayer structures of membranes with other polymer layers. In addition, in JP2003-50316-A and JP2003-207640-A, it is described that non-cyclic olefin monomers and cyclic olefin monomers are copolymerized with aromatic vinyl monomers represented by styrene to form ternary Copolymer, a technology for making a retardation film from a copolymer. Furthermore, in JP2003-90912-A, it is described that an alignment film containing a norbornene-based resin and an alignment film containing a styrene-maleic anhydride copolymer resin are laminated through an adhesive layer to form a retardation film. ; In JP2004-167823-A, a technique in which a polystyrene-based sheet is laminated on a polyolefin-based multilayer film is described. In addition, JP2006-192637-A also describes a technique in which a second layer containing an acrylic resin composition containing rubber particles is laminated on a first layer containing a styrene resin film without interposing an adhesive layer. , made of retardation film.

In addition, in the IPS mode, which is a driving mode of the liquid crystal display device, the liquid crystal molecules are aligned almost parallel to the substrate surface and in almost the same direction. excellent. However, even in various liquid crystal display devices with improved viewing angle characteristics typified by the IPS mode, viewing angle dependence still occurs.

In order to compensate the viewing angle dependence of the IPS mode liquid crystal display device, various technical proposals have been proposed. As one of them, a method of compensating the viewing angle of a polarizing plate with a retardation plate is effective. For example, in JPH02-160204-A, it is described that the ratio of the retardation value when incident from the vertical direction to the retardation value when incident from the direction inclined 40 degrees from the normal is within a certain range, for example, in the thickness Retardation film oriented in different directions. In addition, JPH07-230007-A describes a retardation film in which the angular dependence of the retardation value is controlled by thermally shrinking a uniaxially stretched thermoplastic resin film in a predetermined form, for example, also in the thickness direction. Oriented retardation film. By arranging such a retardation plate oriented in the thickness direction, among two polarizing plates arranged to sandwich a liquid crystal cell, the transmission axis of the adjacent polarizing plate is parallel to the slow axis of the retardation plate. Between either polarizing plate and the liquid crystal cell substrate, it is effective for compensating the viewing angle.

In addition, in T.Ishinabe et al., 'Novel Wide Viewing Angle Polarizer with High Achromaticity', SID 00DIGEST, p.1094-1097, it is described that the N _z coefficients defined above are 0.25 and 0.8, and thickness orientation is carried out. The retardation plate has a better effect. Furthermore, JPH11-133408-A describes a technique in which, for the IPS mode, a retardation film having an optical axis perpendicular to the substrate surface in a positive uniaxial manner is disposed between the liquid crystal cell substrate and the polarizing plate (Compensation layer), that is, a phase difference film that is uniaxially oriented in the thickness direction.

However, these thickness-oriented retardation plates are poor in productivity and require precise processing, resulting in expensive products.

Furthermore, JPH10-54982-A describes the following technique for compensating the viewing angle dependence of an IPS mode liquid crystal display device: by installing a negative uniaxial phase difference between the liquid crystal cell substrate and at least one polarizing plate plate (optical compensation sheet) to improve viewing angle dependence. This publication shows an example in which the optical axis of a retardation plate having negative uniaxiality, that is, the phase advance axis, is arranged parallel to the long axis of the liquid crystal molecules. Therefore, it is desirable to laminate a film used for the above-mentioned optical compensation on a polarizing plate and supply it as an optical compensation film-integrated polarizing plate. However, in the optical compensation mechanism proposed so far, problems such as color shift and hue inversion cannot be sufficiently solved, and further optimization is desired.

In addition, in the case of laminating two or more retardation films, even if the orientation angle distribution of each retardation film monomer is uniform, when they are laminated, color irregularities may occur at specific positions, so there are question.

Contents of the invention

An object of the present invention is to provide a composite polarizing plate having a retardation plate that is easy to manufacture and exhibiting 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 in which local color unevenness hardly occurs even though 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 having excellent viewing angle characteristics.

According to the present invention, it is possible to provide a composite polarizing plate in which a transparent protective film is laminated on one surface of a polarizing film via a first adhesive layer, and a first layer containing an olefin-based resin is laminated on the other surface of the polarizing film via a second adhesive layer. The retardation film, and further, a second retardation film is laminated on the outside of the above-mentioned first retardation film through an adhesive layer, and the second retardation film has the following three-layer structure, and the three-layer structure is The core layer made of styrene resin has a structure in which skin layers made of a (meth)acrylic resin composition containing rubber particles are formed on both surfaces.

More preferably, in the first retardation film, the in-plane retardation value is 30 to 150 nm, and has the following refractive index anisotropy, that is, the in-plane slow axis direction, the in-plane advance axis direction, and the thickness direction When the refractive index is set to n _x , n _y and n _z respectively, the N _z coefficient defined by the formula: (n _x - n _z )/(n _x - n _y ) is greater than 1 and less than 2, that is, it satisfies the following formula (1),

1<(n _x -n _z )/(n _x -n _y )<2 (1)

In the second retardation film, the in-plane retardation value is 20 to 120 nm, and has the following refractive index anisotropy, that is, the N _z coefficient as defined above satisfies greater than -2 and less than -0.5, that is, satisfies the following formula ( 2).

-2＜(n _x -n _z )/(n _x -n _y )＜-0.5 (2)

Preferably, the first retardation film and the second retardation film are laminated so that the change in the angle formed by the orientation angles of the first retardation film and the second retardation film is 0.4° or less within an interval of 10 cm.

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

In the second retardation film, the glass transition temperature of the styrene-based resin forming the core layer is preferably 120° C. or higher, and the glass transition temperature of the (meth)acrylic resin composition forming the skin layer is preferably 120° C. or lower.

The first retardation film containing an olefin-based resin and the polarizing film can be bonded together using a water-based adhesive containing an aqueous solution of a water-soluble polyvinyl alcohol-based resin. The water-based adhesive preferably contains a water-soluble epoxy compound. In addition, the first retardation film and the polarizing film may be bonded with an adhesive agent formed of an epoxy resin composition containing an epoxy resin cured by irradiation with active energy rays or heating. When the epoxy-based resin composition is used as an adhesive, the epoxy-based resin preferably has one or more epoxy groups bonded to an alicyclic ring in the molecule.

Furthermore, according to the present invention, it is possible to provide 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. In addition, it is also possible to provide an IPS mode liquid crystal display device in which any of the above polarizing plates is disposed on one side of the IPS mode liquid crystal cell, and a polarizing plate having a transparent protective film on the liquid crystal cell side is disposed on the other side, The transparent protective film is a transparent protective film having an in-plane retardation value of 10 nm or less and an absolute value of thickness direction retardation value of 15 nm or less.

The in-plane retardation value Re of the film is a value obtained by multiplying the film thickness by the in-plane refractive index difference, and is defined by the following formula (3). In addition, the retardation value Rth in the thickness direction of the film is a value obtained by multiplying the thickness of the film by the difference between the average refractive index in the plane and the refractive index in the thickness direction, and is defined by the following formula (4). Furthermore, the N _z coefficient is defined by the following equation (5) as described above in the equations (1) and (2).

In-plane retardation value Re＝(n _x -n _y )×d (3)

Thickness retardation value Rth＝{(n _x + _ny )/2-n _z )×d (4)

N _z coefficient = (n _x -n _z )/(n _x -n _y ) (5)

(where n _x , _ny and _nz are the refractive indices in the three-axis directions of the film defined previously, and d is the thickness of the film).

Re, Rth, and _Nz coefficients can be measured using various commercially available phase difference meters.

These values are conventionally measured at a wavelength near the center of visible light as representative values, and the retardation value and _Nz coefficient referred to in this specification are values measured at a wavelength of 590 nm.

Description of drawings

FIG. 1 is a schematic cross-sectional view showing an example of the layer constitution of the composite polarizing plate of the present invention.

FIG. 2 is a distribution diagram of the contrast ratio of a liquid crystal display device fabricated using the composite polarizing plate of Example 1. FIG.

3 is a graph showing the distribution of contrast ratios of a liquid crystal display device produced using the composite polarizing plate of Example 2. FIG.

4 is a graph showing the distribution of contrast ratios of a liquid crystal display device fabricated using the composite polarizing plate of Example 3. FIG.

FIG. 5 is a distribution diagram of the contrast ratio of a liquid crystal display device manufactured using the composite polarizing plate of Example 4. FIG.

6 is a graph showing the distribution of contrast ratios of a liquid crystal display device produced using the composite polarizing plate of Comparative Example 1. FIG.

7 is a graph showing the distribution of contrast ratios of a liquid crystal display device fabricated using the composite polarizing plate of Example 5. FIG.

8 is a graph obtained by plotting the angle formed by the orientation angles of two retardation films constituting each composite polarizing plate in the width direction for two types of composite polarizing plates used in Example 5. FIG.

Symbol Description

100 composite polarizing plates

101 polarizing film

102 transparent protective film

103 The first retardation film

104 adhesive layer

105 second retardation film

106 first adhesive (adhesive agent) layer

107 second adhesive layer

108 adhesive layer (adhesive agent)

109 spacers

31 core layer

32 cortex

Detailed ways

[Composite polarizing plate]

FIG. 1 is a schematic cross-sectional view showing an example of the layer constitution of the composite polarizing plate of the present invention. The composite polarizing plate 100 shown in FIG. 1 includes: a polarizing plate laminated in the order of a transparent protective film 102, a polarizing film 101, and a first retardation film 103 containing an olefin-based resin; A second retardation film 105 is laminated on a retardation film 103 via an adhesive layer 104 . A transparent protective film 102 is stacked on one side of the polarizing film 101 via a first adhesive layer 106 , and a first retardation film 103 containing an olefin resin is stacked on the other side of the polarizing film 101 via a second adhesive layer 107 .

The second retardation film 105 has a three-layer structure in which skin layers 32, 32 made of a (meth)acrylic resin composition containing rubber particles are formed on both sides of a core layer 31 containing styrene resin. 3-layer structure. On the surface of the second retardation film 105 opposite to the surface bonded to the first retardation film 103, an adhesive layer 108 for bonding other components such as a liquid crystal cell is usually provided. Before being attached to other components, a spacer 109 is provided to pre-stick and protect the surface of the adhesive layer 108 . In addition, in FIG. 1 , for ease of understanding, some layers are separated and shown, but actually adjacent layers are in close contact with each other. Hereinafter, each member constituting the composite polarizing plate will be described in detail.

[Polarizing film]

The polarizing film 101 used in the present invention is usually a polarizing film manufactured through the steps of: uniaxially stretching a polyvinyl alcohol-based resin film by a known method; A step of dyeing the polyvinyl alcohol-based resin film to adsorb the dichroic dye; a step of treating the polyvinyl alcohol-based resin film having the dichroic dye adsorbed thereon 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-based resin, a resin obtained by saponifying a polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include other monomers copolymerizable with vinyl acetate, copolymers of vinyl acetate, and the like, in addition to polyvinyl acetate that is a homopolymer of 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 degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

A film obtained by forming such a polyvinyl alcohol-based resin into a film can be used as a roll film of a polarizing film. The method of forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a known method can be used to form a film. The film thickness of a polyvinyl alcohol-type roll film is not specifically limited, For example, it is about 10 micrometers - 150 micrometers.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When performing uniaxial stretching after dyeing, this uniaxial stretching may be performed before boric-acid treatment or during boric-acid treatment. In addition, uniaxial stretching may be performed in these multiple stages.

The uniaxial stretching may be uniaxially stretched between rolls having different rotational speeds, or may be uniaxially stretched using heated rolls. In addition, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which the polyvinyl alcohol-based resin film is stretched in a state where the polyvinyl alcohol-based resin film is swollen using a solvent such as water. The draw ratio is usually about 3 to 8 times.

As a method of dyeing a polyvinyl alcohol-type resin film with a dichroic dye, the method of immersing a polyvinyl-alcohol-type resin film in the aqueous solution containing a dichroic dye can be employ|adopted, for example. Specifically, iodine and a dichroic dye can be used as the dichroic dye. In addition, it is preferable to previously perform a water immersion treatment on the polyvinyl alcohol-based resin film before the dyeing treatment.

When using iodine as a dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is generally employed. Usually, content of the iodine in this aqueous solution is about 0.01-1 weight part with respect to 100 weight part of water. Moreover, content of potassium iodide is about 0.5-20 weight part with respect to 100 weight part of water normally. The temperature of the aqueous solution used for dyeing is about 20-40 degreeC normally.

In addition, the immersion time (dyeing time) in this aqueous solution is about 20 to 1800 seconds normally.

On the other hand, when using a dichroic dye as a dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous dye solution containing a water-soluble dichroic dye is generally employed. The content of the dichroic dye in the aqueous dye solution is usually about 1×10 ^-4 to 10 parts by weight, preferably about 1×10 ^-3 to 1 part by weight, based on 100 parts by weight of water. The aqueous solution may also contain inorganic salts such as sodium sulfate as dyeing aids. The temperature of the aqueous dichroic dye solution used for dyeing is usually 20 to 80°C, and the immersion time (dyeing time) in the aqueous dye solution is usually about 10 to 1800 seconds.

The boric acid treatment after dyeing of the dichroic dye is generally performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid.

Usually, content of boric acid in the aqueous solution containing boric acid is about 2-15 weight part normally with respect to 100 weight part of water, Preferably it is about 5-12 weight part. When using iodine as the dichroic dye in the dyeing treatment step, the aqueous solution containing boric acid used in the boric acid treatment step preferably contains potassium iodide. In this case, the amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight, based on 100 parts by weight of water. The immersion time in the aqueous solution containing boric acid is about 60 to 1200 seconds normally, Preferably it is about 150 to 600 seconds, More preferably, it is about 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50°C or higher, preferably 50 to 85°C, more preferably 60 to 80°C.

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

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

The moisture content of the polarizing film can be reduced to a practical level by the drying treatment. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the water 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 the moisture content exceeds 20 weight%, the thermal stability of a polarizing film may worsen.

The thickness of the polarizing film obtained by adsorbing and aligning the dichroic dyes in this way can usually be set to about 5 to 40 μm.

[First Retardation Film Containing Olefin-Based Resin]

In the composite polarizing plate of the present invention, the first retardation film 103 disposed on the liquid crystal cell side is a film containing an olefin-based resin. The olefin-based resin refers to a structure derived from an alicyclic olefin containing chain aliphatic olefins such as ethylene and propylene, or norbornene and its substitutes (hereinafter, these are collectively referred to as norbornene-based monomers). unit resin. The olefin-based resin may be a copolymer using two or more monomers.

Among them, as the olefin-based resin, it is preferable to use a cyclic olefin-based resin that is a resin mainly containing a structural unit derived from an alicyclic olefin. Typical examples of the alicyclic olefin constituting the cyclic olefin-based resin include norbornene-based monomers and the like. The so-called norbornene refers to a compound in which one carbon-carbon bond of norbornane becomes a double bond. According to the IUPAC nomenclature, it is named bicyclo[2,2,1] hepta-2-ene (bicyclo[2,2, 1] compounds of hept-2-ene). As an example of a norbornene substituent, the double bond position of norbornene is set at the 1,2-position, 3-substitution, 4-substitution, 4,5-disubstitution etc. are mentioned, and further, Dicyclopentadiene, dimethanooctahydronaphthalene, and the like are also used as monomers constituting the cyclic olefin-based resin.

The cyclic olefin-based resin may or may not have a norbornane ring in its structural unit. Examples of norbornene-based monomers that form cyclic olefin-based resins that do not have a norbornane ring in their structural units include compounds that become five-membered rings by ring opening, and norbornene, dicyclopentadiene, and Diene, 1- or 4-methylnorbornene, 4-phenylnorbornene, and the like. When the cyclic olefin-based resin is a copolymer, the arrangement state of its molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer.

More specific examples of cyclic olefin-based resins include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers, and mixing them with maleic acid , modified polymers obtained by addition of cyclopentadiene, etc., and polymers or copolymers obtained by hydrogenating them, addition polymers of norbornene-based monomers, norbornene-based monomers and other monomers addition copolymers, etc. Examples of other monomers to be used in copolymers include α-olefins, cycloolefins, non-conjugated dienes, and the like. In addition, the cyclic olefin-based resin may be a copolymer using a norbornene-based monomer and one or two or more other alicyclic olefins.

In the above specific examples, as the cyclic olefin-based resin, a hydrogenated ring-opening polymer using a norbornene-based monomer is preferably used. Such a cyclic olefin-based resin can be stretched to form a retardation film. In addition to stretching, it can be made into Retardation film with high uniformity and large retardation value.

Commercially available products of cyclic olefin-based resins using such norbornene-based monomers include "ZEONEX" and "ZEONOR" sold by Japan ZEON Co., Ltd., and "ZEONOR" sold by JSR Co., Ltd. ARTON” etc. Films of these cyclic olefin-based resins and stretched films thereof are also commercially available, for example, "ZEONOR film" released by Japan ZEON Co., Ltd., "ZEONOR film" sold by JSR Co., Ltd. "ARTON Membrane", "Escina" marketed by Sekisui Chemical Co., Ltd., etc.

In addition, as the first retardation film used in the present invention, a film composed of a mixed resin containing two or more olefin-based resins, or a film composed of a mixed resin of an olefin-based resin and another thermoplastic resin can be used. For example, as a mixed resin containing two types of olefin resins, a mixture of the above-mentioned cyclic olefin resin and chain aliphatic olefin resin is mentioned. When a mixed resin of an olefin-based resin and another thermoplastic resin is used, the other thermoplastic resin can be appropriately selected according to the purpose. Specific examples include polyvinyl chloride resins, cellulose resins, polystyrene resins, acrylonitrile/butadiene/styrene copolymer resins, acrylonitrile/styrene copolymer resins, (meth)acrylic resins, Resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resins, ethylene terephthalate resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polyarylate resins, liquid crystal resins, Polyamide-imide resin, polyimide resin, polytetrafluoroethylene resin, etc. These thermoplastic resins may be used alone or in combination with one or more other resins. In addition, the above-mentioned thermoplastic resin may be used after undergoing arbitrary appropriate polymer modification. Examples of polymer modification include copolymerization, crosslinking, modification of molecular terminals, imparting stereoregularity, and the like.

When a mixed resin of an olefin-based resin and another thermoplastic resin is used, the content of the other thermoplastic resin is usually about 50% by weight or less, preferably about 40% by weight or less, based on the entire resin. By setting the content of other thermoplastic resins within this range, a retardation film having a small absolute value of the photoelastic constant, exhibiting favorable wavelength dispersion characteristics, and excellent durability, mechanical strength, and transparency can be obtained.

Such an olefin-based resin can be formed into a film by a casting method from a solution, a melt extrusion method, or the like. When forming a film from two or more mixed resins, the film forming method is not particularly limited. For example, the following method can be used: the resin component is stirred and mixed with the solvent according to the specified ratio to obtain a uniform solution, and the solution is used by casting. The method of mold making; the method of melting and mixing the resin components according to the prescribed ratio, and making a film by melt extrusion method, etc.

The above olefin-based resin-containing film may contain other components such as residual solvents, stabilizers, plasticizers, anti-aging agents, antistatic agents, and ultraviolet absorbers as needed, within the range that does not impair the object of the present invention. In addition, in order to reduce the surface roughness, a leveling agent may also be contained.

In the first retardation film containing the above-mentioned olefin-based resin film used in the present invention, it is preferable that the in-plane retardation value Re is 30 to 150 nm, and has a refraction with an _Nz coefficient greater than 1 and less than 2 defined by the above formula (5). rate anisotropy.

The olefin-based resin film having the above-mentioned refractive index anisotropy can be obtained by known longitudinal uniaxial stretching, tenter transverse uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, etc., to obtain The stretching ratio and stretching speed can be appropriately adjusted according to the desired retardation value. In addition, various temperatures such as preheating temperature, stretching temperature, heating set temperature, and cooling temperature during stretching can be adjusted. Choose the appropriate pattern.

The stretched cyclic olefin-based resin film used in the present invention preferably has a thickness in the range of 20 to 80 μm, 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, the handling of the film is difficult, and it tends to be difficult to express a predetermined retardation value. On the other hand, if the thickness exceeds 80 μm, it becomes a film with poor processability, and the transparency decreases. Or the weight of the obtained polarizing plate may become large.

[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 property, stability of retardation value, and the like. The material constituting such a transparent protective film is not particularly limited, and examples thereof include (meth)acrylic resins typified by methyl methacrylate resins and polyolefin-based resins typified by propylene resins. Resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polyvinyl acetate Resin, polyvinylidene chloride-based resin, polyamide-based resin, polyacetal-based resin, polycarbonate-based resin, modified polyphenylene ether-based resin, polybutylene terephthalate-based resin, polyparaphenylene Ethylene dicarboxylate-based resins, polysulfone-based resins, polyethersulfone-based resins, polyarylate-based resins, polyamide-imide-based resins, polyimide-based resins, and the like.

These resins can be used alone or in combination with one or more other resins. In addition, these resins can be used after undergoing any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, modification of molecular terminals, control of stereoregularity, and various types of polymerization. Modifications such as mixing and the like of the reaction between substances.

Among these, as the material of the above-mentioned transparent protective film, it is preferable to use (meth)acrylic resin, ethylene terephthalate resin, acrylic resin, or fiber resin represented by methyl methacrylate resin. Prime resin.

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

The methyl methacrylate resin is usually obtained by polymerizing a monofunctional monomer mainly composed of methyl methacrylate in the presence of a radical polymerization initiator and a chain transfer agent. During polymerization, a small amount of polyfunctional monomer may also be copolymerized therewith.

Examples of monofunctional monomers that can be copolymerized with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, Methacrylates other than methyl methacrylate such as 2-ethylhexyl methacrylate and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, Acrylates such as phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; 2-(hydroxymethyl)methyl acrylate, 2-(1-hydroxyethyl)methyl acrylate Hydroxyalkyl acrylates such as esters, ethyl 2-(hydroxymethyl)acrylate, and butyl 2-(hydroxymethyl)acrylate; unsaturated acids such as methacrylic acid and acrylic acid; chlorostyrene and bromostyrene substituted styrenes such as vinyltoluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; phenyl Unsaturated imides such as maleimide and cyclohexylmaleimide, etc. These copolymerizable monomers may be used alone or in combination with one or more other monomers.

Examples of polyfunctional monomers that can be copolymerized with methyl methacrylate include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, Acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate and other ethylene glycol or its oligomers Compounds in which hydroxyl groups at both terminals are esterified with acrylic acid or methacrylic acid; compounds in which hydroxyl groups at both terminals of propylene glycol or its oligomers are esterified with acrylic acid or methacrylic acid; neopentyl glycol di(meth)acrylate, Compounds in which the hydroxyl groups of divalent alcohols such as hexanediol di(meth)acrylate and butanediol di(meth)acrylate are esterified with acrylic acid or methacrylic acid; olefination of bisphenol A and bisphenol A Oxygen adducts, or compounds obtained by esterifying the hydroxyl groups at both ends of their halogen substitutes with acrylic acid or methacrylic acid; trimethylolpropane and pentaerythritol and other polyols esterified with acrylic acid or methacrylic acid Compounds, and compounds that allow the epoxy groups of glycidyl acrylate or glycidyl methacrylate to undergo ring-opening addition to their terminal hydroxyl groups; make glycidyl acrylate or glycidyl methacrylate Epoxy ring-opening addition to dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, their halogen substitutes, and their alkylene oxide adducts compounds; allyl (meth)acrylate; aromatic divinyl compounds such as divinylbenzene, etc. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used.

The methyl methacrylate resin may be modified by further reacting copolymerizable functional groups. As this reaction, for example, the methyl ester group of methyl acrylate and the hydroxyl group of 2-(hydroxymethyl)methyl acrylate are demethanolized in the polymer chain, and the carboxyl group of acrylic acid and 2-(hydroxymethyl) ) The dehydration condensation reaction in the polymer chain that occurs at the hydroxyl group of methyl acrylate, etc.

Such a methyl methacrylate resin can be easily obtained as a commercial product, for example, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), ACRYPET (manufactured by Mitsubishi Rayon Corporation), Delpet (manufactured by Asahi Kasei Co., Ltd.) , Parapet (manufactured by Kuraray Co., Ltd.), Acryviewa (manufactured by Nippon Shokubai Co., Ltd.), etc.

The ethylene terephthalate-based resin refers to 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.

Examples of other diol components include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, Polytetramethylene glycol, etc.

These dicarboxylic acid components or diol components can be used in combination of 2 or more types as needed. In addition, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-hydroxyethoxybenzoic acid may be used in combination. In addition, as other copolymerization components, dicarboxylic acid components or diol components containing a small amount of amide bonds, urethane bonds, ether bonds, carbonate bonds, etc. may also be used.

As a method for producing ethylene terephthalate-based resins, the method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as needed) can be used, and the Dialkyl esters of phthalic acid are transesterified with ethylene glycol (and dialkyl esters of other dicarboxylic acids or other diols as required), followed by polycondensation; making terephthalic acid A method in which ethylene glycol ester (and other dicarboxylic acid if necessary) is polycondensed in the presence of a catalyst, etc. Furthermore, solid-phase polymerization may be performed to increase the molecular weight or decrease low molecular weight components as necessary.

The propylene-based resin refers to a resin polymerized using a polymerization catalyst using a chain olefin monomer in which 80% by weight or more of repeating units are propylene monomers. Among them, a homopolymer of propylene is preferable. Among homopolymers of propylene, a polymer having a soluble content (CXS component) in xylene at 20° C. is more preferably 1% by weight or less, and a polymer having a CXS component of 0.5% by weight or less is still more preferable. Also preferred are copolymers in which propylene is used as a main body and a comonomer copolymerizable therewith is carried out in a ratio of 1 to 20% by weight, preferably 3 to 10% by weight.

When a propylene copolymer is used, ethylene, 1-butene, and 1-hexene are preferable as comonomers copolymerizable with propylene. Among them, a copolymer obtained by copolymerizing ethylene in a ratio of 3 to 10% by weight is preferable from the viewpoint of relatively excellent transparency. By setting the copolymerization ratio of ethylene to 1% by weight or more, the effect of improving transparency can be exhibited. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin may decrease, which may impair the heat resistance required for the protective film.

The so-called cellulose-based resin refers to a part of the hydrogen atoms in the hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linters, wood pulp (hardwood pulp, conifer pulp) and the like by acetyl, propionyl and/or butyryl. Or all cellulose organic acid esters or cellulose mixed organic acid esters. For example, resins containing acetate, propionate, butyrate and mixed esters thereof of cellulose are exemplified. Among them, 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 of producing a transparent protective film adhered to a polarizing film using the above methyl methacrylate resin, ethylene terephthalate resin, acrylic resin, cellulose resin, etc., it can be selected according to the resin. A suitable method is not particularly limited. For example, the following methods can be used: a solvent casting method in which a resin dissolved in a solvent is cast onto a metal belt or cylinder, and the solvent is removed by drying to obtain a film; Extrude and cool to obtain a film melt extrusion method, etc.

In the melt extrusion method, a single-layer film may be extruded, or a multi-layer film may be simultaneously extruded.

The film that can be used as a protective film can be easily obtained as a commercial product. For the methyl methacrylate resin film, for example, Technoloy (manufactured by Sumitomo Chemical Co., Ltd.), Acrylite, and Acryplen (above, Mitsubishi Rayon Corporation), Delaglas (Asahi Kasei Corporation), Paraglas and Comoglas (above, Kuraray Corporation), Acryviewa (Nippon Shokubai Corporation), etc.

Examples of the ethylene terephthalate-based resin film include Novaclear (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (manufactured by Teijin Chemicals) according to their respective brand names.

As the acrylic resin film, for example, FILMAXCPP film (manufactured by FILMAX Corporation), Suntox (manufactured by Sun Tox Corporation), Tocello (manufactured by Tocello Corporation), Toyobo Pylen film (manufactured by Toyoyobo Co., Ltd.), Torayfan (manufactured by Toray Film Processing Co., Ltd.), Nippon Polyeichisu (manufactured by Nippon Polyeichisu Co., Ltd.), Taiko FC (manufactured by Futamura Chemical Co., Ltd.), and the like.

In addition, examples of the cellulose-based resin film include FUJITAC TD (manufactured by Fuji Film Corporation) and Konicaminolta TAC film KC (manufactured by Konica Minolta Optical Co., Ltd.) according to their respective trade names.

Antiglare properties (haze) can be imparted to the transparent protective film used in the present invention. As a method of imparting anti-glare properties, for example, the following methods can be used: a method of mixing inorganic fine particles or organic fine particles into a raw material resin to form a film; using multi-layer extrusion, using a resin mixed with fine particles to form one side, and using a resin not mixed with fine particles A method in which the resin constitutes the other side to make a two-layer film, or a method in which a resin mixed with particles is placed on the outside to make a three-layer film; inorganic particles or organic particles are mixed with a curable base material (Binda) resin to form The formed coating liquid, the method of applying the coating liquid to one side of the film, curing the base resin to provide the anti-glare layer, and the like.

Examples of 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, etc. In addition, examples of organic fine particles include crosslinked polyacrylic acid particles, methyl methacrylate/styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethacrylate particles, silicone resin particles, polyimide particles, etc.

The haze value of the transparent protective film provided with antiglare property is preferably in the range of 6 to 45%. When the haze value of the anti-glare protective film is less than 6%, sufficient anti-glare effect may not be expressed. Moreover, when the haze value exceeds 45%, the screen of the liquid crystal display device to which this film is applied may become whitish, and may cause the fall of an image quality.

The haze value can be measured in accordance with JIS K7136 using a commercially available haze meter, for example, haze and transmittance meter HM-150 (manufactured by Murakami Color Technology Laboratory Co., Ltd.). When measuring the haze value, in order to prevent warping of the film, for example, it is preferable to use a measurement sample in which the film surface is bonded to a glass substrate with an optically transparent adhesive such that the anti-glare property-imparting surface becomes the surface.

Functional layers such as a conductive layer, a hard coat layer, and a low-reflection layer may also be provided on the above-mentioned transparent protective film. When forming the above-mentioned antiglare layer, the coating liquid may be selected from resin compositions having these functions.

Moreover, saponification treatment, corona treatment, plasma treatment, etc. are preferably given to a transparent protective film before bonding with a polarizing film.

The thickness of the transparent protective film is usually about 1 to 500 μm, preferably 10 to 200 μm, more preferably 20 to 100 μm, from the viewpoint of strength, handleability, and the like. As long as the thickness is within this range, the polarizing film can be mechanically protected, and even if exposed to high temperature and high humidity, the polarizing film can maintain stable optical characteristics without shrinking.

[First Adhesive Layer and Second Adhesive Layer]

As a method of laminating the transparent protective film 102 and the first retardation film 103 containing an olefin-based resin on the polarizing film 101, a method of integrating the first and second adhesive layers 106 and 107 may be employed. In this case, the thickness of the adhesive layer is preferably 0.1 to 35 μm, more preferably 0.1 to 15 μm. As long as it is within this range, the laminated transparent protective film and the first retardation film containing an olefin-based resin and the polarizing film will not be detached or peeled off, and practically no problematic adhesive force can be obtained.

As the adhesive layer, an appropriate adhesive layer can be appropriately used according to the type and purpose of the adherend.

For example, there are solvent-based adhesives, emulsion adhesives, pressure-sensitive adhesives, remoisturable adhesives, polycondensation adhesives, solvent-free adhesives, film adhesives, hot-melt adhesives, and the like.

One preferable adhesive agent which forms the 2nd adhesive agent layer which bonds a polarizing film and a 1st retardation film together is a water-based adhesive agent. As such a water-based adhesive, there is, for example, an adhesive mainly composed of a polyvinyl alcohol-based resin. A commercially available adhesive may be used, or a commercially available adhesive may be mixed with a solvent or an additive. As a commercially available polyvinyl-alcohol-type resin which can be used as a water-based adhesive agent, there exist KL-318 by Kuraray Corporation etc., for example.

The water-based adhesive may contain a crosslinking agent. As the crosslinking agent, amine compounds, aldehyde compounds, methylol compounds, epoxy compounds, isocyanate compounds, polyvalent metal salts and the like are preferable, and epoxy compounds are particularly preferable. Examples of commercially available crosslinking 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., and the like.

In addition, another preferable adhesive agent includes an adhesive agent composed of an epoxy resin composition containing an epoxy resin cured by irradiation with active energy rays or heating.

When using an adhesive composed of such an epoxy resin composition, the adhesion between the transparent protective film and the first retardation film containing an olefin resin and the polarizing film can be carried out by the following method, that is, for the presence of these The coating layer of the adhesive between the films is irradiated with active energy rays or heated to cure the 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 addition, in this specification, an epoxy resin means the compound which has 2 or more epoxy groups in a molecule|numerator.

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

Hydrogenated epoxy resins can be obtained by glycidyl etherification of nuclear hydrogenated polyhydroxyl compounds. The nuclear hydrogenated polyhydroxyl compounds are made of polyhydroxyl compounds as raw materials for aromatic epoxy resins in the presence of catalysts. It can be obtained by selective nuclear hydrogenation reaction under pressure. As the aromatic epoxy resin, for example, bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; Novolac type epoxy resins such as epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde phenol novolac epoxy resin; glycidyl ether of tetrahydroxydiphenylmethane, glycidyl ether of tetrahydroxybenzophenone, cyclic Polyfunctional epoxy resins such as oxidized polyvinyl phenol, etc. Among hydrogenated epoxy resins, glycidyl ethers of hydrogenated bisphenol A are preferred.

The alicyclic epoxy resin refers to an epoxy resin having one or more epoxy groups bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" refers to an oxygen atom -O- bridged in the structure represented by the following formula, where m is an integer of 2-5.

【Chemical 1】

A compound in which one or more hydrogens in (CH ₂ ) _m in the above formula are bonded to another chemical structure can be an alicyclic epoxy compound. One or more hydrogens in (CH ₂ ) _m may be appropriately substituted with linear alkyl groups such as methyl and ethyl. Among alicyclic epoxy compounds, rings having an oxabicyclohexane ring (a substance with m=3 in the above formula (1)) and an oxabicycloheptane (a substance with m=4 in the above formula) Oxygen-based compounds are preferable because they exhibit good adhesiveness. Hereinafter, although the structure of the alicyclic epoxy compound used preferably in this invention is illustrated concretely, it is not limited to these compounds.

(a) Epoxycyclohexylmethyl epoxycyclohexane carboxylates shown in the following formula (I):

【Chemical 2】

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

(b) Epoxycyclohexane carboxylate esters of alkanediols represented by the following formula (II):

【Chemical 3】

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

(c) Epoxycyclohexylmethyl esters of dicarboxylic acids represented by the following formula (III):

【Chemical 4】

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

(d) epoxy cyclohexyl methyl ethers of polyethylene glycol shown in the following formula (IV):

【Chemical 5】

(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) epoxy cyclohexyl methyl ethers of alkanediol shown in the following formula (V):

【Chemical 6】

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

(f) Diepoxy triple spiro compounds shown in the following formula (VI):

【Chemical 7】

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

(g) the diepoxy group single spiro compound shown in the following formula (VII):

【chemical 8】

(In the formula, R ¹³ and R ¹⁴ 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):

【Chemical 9】

(In the formula, ^R15 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

(i) Epoxycyclopentyl ethers represented by the following formula (IX):

【chemical 10】

(In the formula, ^R16 and ^R17 independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

(j) Diepoxy tricyclodecanes represented by the following formula (X):

【chemical 11】

(In the formula, ^R18 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

Among the alicyclic epoxy-based resins exemplified above, the following alicyclic epoxy-based resins are preferably used because they are commercially available or their analogues are relatively easy to obtain.

(A) esterification of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and (7-oxa-bicyclo[4.1.0]hept-3-yl)methanol [in the above formula ( In I), the compound of 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 ) Esterification product of methanol [compound of R ¹ =4-CH ₃ , R ² =4-CH ₃ in the above formula (I)]

(C) Esterification product of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and 1,2-ethanediol [in the above formula (II), R ³ =R ⁴ =H, n = 2 compounds]

(D) Esterification product of (7-oxabicyclo[4.1.0]hept-3-yl)methanol and adipic acid [in the above formula (III), R ⁵ =R ⁶ =H, p=4 compound]

(E) Esterification product of (4-methyl-7-oxabicyclo[4.1.0]hept-3-yl)methanol and adipic acid [in the above formula (III), R ⁵ =4-CH ₃ , R ⁶ =4-CH ₃ , the compound of p=4]

(F) Etherification of (7-oxabicyclo[4.1.0]hept-3-yl)methanol and 1,2-ethanediol [in the above formula (V), R ⁹ =R ¹⁰ =H, Compounds with r=2]

Moreover, as an aliphatic epoxy resin, the polyglycidyl ether of an aliphatic polyhydric alcohol or its alkylene oxide adduct is mentioned. More specifically, diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane Ether, diglycidyl ether of polyethylene glycol, diglycidyl ether of propylene glycol, adding one or more kinds of alkylene oxides (ethylene oxide) to aliphatic polyols such as ethylene glycol, propylene glycol, and glycerin Alkanes, propylene oxide), polyglycidyl ethers of polyether polyols, etc.

As for the epoxy resin constituting the adhesive agent containing the epoxy resin composition, only one type may be used, or two or more types may be used in combination. The epoxy equivalent of the epoxy resin used for this composition exists in the range of 30-3000 g/equivalent normally, Preferably it is 50-1500 g/equivalent. When the epoxy equivalent is less than 30 g/equivalent, the flexibility of the composite polarizing plate after curing may decrease, or the adhesive strength may decrease. On the other hand, if it exceeds 3000 g/equivalent, the compatibility with other components contained in the adhesive may decrease.

In this adhesive, cationic polymerization is preferably used as the curing reaction of the epoxy resin from the viewpoint of reactivity. Therefore, it is preferable to mix a cationic polymerization initiator in the curable epoxy resin composition as an adhesive. Through the irradiation or heating of active energy rays such as visible light, ultraviolet rays, X-rays, and electron rays, the cationic polymerization initiator produces cationic species or Lewis acids, thereby initiating the polymerization of epoxy groups. Any type of cationic polymerization initiator provides potential, and is preferable from the viewpoint of handleability. Hereinafter, cationic polymerization initiators that generate cationic species or Lewis acids by irradiation of active energy rays and initiate polymerization of epoxy groups are called "photocationic polymerization initiators." Cationic species or Lewis acids are generated by heat to initiate epoxy group polymerization. Cationic polymerization initiators based on polymerization reactions are called "thermal cationic polymerization initiators".

The method of curing the adhesive by irradiation of active energy rays using a photocationic polymerization initiator can be cured at room temperature, and the consideration of heat resistance or swelling deformation of the polarizing film can be reduced, and the transparent protective film can be combined with the polarizing film. It is preferable from the standpoint of good adhesion of the film. Moreover, since a photocationic polymerization initiator exerts catalytic activity by light, even if it mixes with an epoxy resin, it is excellent in storage stability and handleability.

It does not specifically limit as a photocationic polymerization initiator, For example, an aromatic diazonium salt; Onium salts like an aromatic iodonium salt, an aromatic sulfonium salt; Aryl ferrocene complex etc. are mentioned, for example.

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

Examples of aromatic sulfonium salts include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl) borate, 4,4'-bis (Diphenylsulfonium) diphenylsulfide bishexafluorophosphate, 4,4'-bis[bis(β-hydroxyethoxy)phenylsulfonium]diphenylsulfide bishexafluoroantimonate, 4 , 4'-bis[bis(β-hydroxyethoxy)phenylsulfonium]diphenylsulfide bis-hexafluorophosphate, 7-[bis(p-tolyl)sulfonium]-2-isopropylthioxanthone Hexafluoroantimonate, 7-[bis(p-tolyl)sulfonium]-2-isopropylthioxanthone tetrakis(pentafluorophenyl)borate, 4-phenylcarbonyl-4'-diphenylsulfonium -Diphenylsulfide hexafluorophosphate, 4-(p-tert-butylphenylcarbonyl)-4'-diphenylsulfonium-diphenylsulfide hexafluoroantimonate, 4-(p-tert-butylphenyl (ylcarbonyl)-4'-(p-tolyl)sulfonium-diphenylsulfide tetrakis(pentafluorophenyl)borate, etc.

In addition, examples of ferrocene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, Xylene-cyclopentadienyliron(II)-tris(trifluoromethylsulfonyl)methanide, etc.

These photocationic polymerization initiators can easily obtain commercial products. For example, if they are named by trade names respectively, "Kayarad PCI-220" and "Kayarad PCI-620" (the above are provided by Nippon Kayaku Co., Ltd. ), "UVI-6990" (manufactured by Union Carbide), "Adeka Optomer SP-150", "Adeka Optomer SP-170" (the above are manufactured by ADEKA Co., Ltd.), "CI-5102" , "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", "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", "DTS-102", "DTS-103" (above manufactured by Midori Chemical Co., Ltd.), "PI-2074" (manufactured by Rhodia), and the like.

These photocationic polymerization initiators may be used individually or in mixture of 2 or more types, respectively. Among them, especially aromatic sulfonium salts have ultraviolet absorption characteristics even in the wavelength range of 300 nm or more, so they are excellent in curability, and can provide cured products with good mechanical strength and adhesive strength, so they are preferably 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 compounding quantity of a photocationic polymerization initiator is less than 0.5 weight part with respect to 100 weight part of epoxy resins, hardening will become insufficient, and there exists a tendency for mechanical strength and adhesive strength to fall. On the other hand, if the compounding amount of the photocationic polymerization initiator is greater than 20 parts by weight relative to 100 parts by weight of the epoxy resin, the ionic substances in the cured product will increase, so the hygroscopicity of the cured product will increase, and there is a possibility that the durability will decrease. .

When using a photocationic polymerization initiator, in curable epoxy resin composition which is an adhesive agent, you may contain a photosensitizer as needed. By using a photosensitizer, the reactivity of cationic polymerization is improved, and the mechanical strength and adhesive strength of a cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halides, and photoreducible dyes.

As a specific photosensitizer, for example, benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; Benzophenone, 2,4-dichlorobenzophenone, methyl phthaloylbenzoate, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino) ) benzophenone derivatives such as benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; such as 2-chloroanthraquinone and 2-methylanthraquinone anthraquinone derivatives; acridone derivatives such as N-methylacridone and N-butylacridone; in addition, α, α-diethoxyacetophenone, benzil, Fluorenones, xanthones, uranyl compounds, halides, etc. These may be used alone or in combination. It is preferable to contain a photosensitizer in the range of 0.1-20 weight part with respect to 100 weight part of curable epoxy resin compositions.

On the other hand, examples of thermal cationic polymerization initiators include benzylsulfonium salts, thiophenium salts, thiolanium salts, benzyl ammonium salts, pyridinium salts, hydrazinium salts, carboxylates, and sulfonate esters. , Aminoimide, etc. These initiators can be easily obtained as commercial products, and if they are named by trade names, "ADEKA OPTON CP77" and "ADEKA OPTON CP66" (manufactured by Asahi Denka Kogyo Co., Ltd.), "CI-2639" can be mentioned. and "CI-2624" (the above manufactured by Nippon Soda Co., Ltd.), "San-Aid SI-60L", "San-Aid SI-80L" and "San-Aid SI-100L" (the above manufactured by Sanshin Chemical Industry Co., Ltd. Co., Ltd.), etc.

The epoxy resin contained in the adhesive can be cured by either photocationic polymerization or thermal cationic polymerization, or can be cured by 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 together.

In addition, the curable epoxy resin composition may further contain compounds that promote cationic polymerization, such as oxetanes and polyols.

Oxetane compounds are compounds having at least a four-membered cyclic ether structure in the molecule, such as 3-ethyl-3-hydroxymethyl oxetane, 1,4-bis[(3- Ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, bis[(3-ethyl-3- Oxetanyl)methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, phenol novolac oxetane, etc. These oxetane compounds can be easily obtained as commercial products. For example, all of them are exemplified by trade names, such as "ARON OXETANE OXT-101", "ARON OXETANE OXT-121", "ARON OXETANE OXT-211 ", "ARON OXETANE OXT-221", "ARON OXETANE OXT-212" (the above are manufactured by Toagosei Co., Ltd.), etc. In the curable epoxy resin composition, these oxetane-based compounds are usually contained in a ratio of 5 to 95% by weight, preferably 30 to 70% by weight.

As the polyols, polyols having acidic groups other than phenolic hydroxyl groups are preferable, and examples thereof include polyol compounds without functional groups other than hydroxyl groups, polyester polyol compounds, polycaprolactone polyol compounds, Hydroxyl polyol compounds, polycarbonate polyol compounds, etc. 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. The compounding quantity of these polyhydric alcohols is 50 weight% or less normally in curable epoxy resin composition, Preferably it is 30 weight% or less.

Furthermore, as long as the effects of the present invention are not impaired, other additives such as ion-scavenging agents, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, fillers, etc. may be added to the curable epoxy resin composition. , flow regulator, plasticizer, defoamer, etc. Examples of ion trapping agents include powdered inorganic compounds such as bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixtures thereof, and examples of antioxidants include hindered phenolic compounds. Department of antioxidants, etc.

Put the adhesive comprising the above curable epoxy resin composition containing epoxy resin on one or both of the adhesive surfaces of the polarizing film and the transparent protective film, or on the adhesive surface of the polarizing film and the first retardation film. After one or both sides are coated, the surfaces coated with the adhesive are bonded together, and the uncured adhesive layer is cured by irradiating active energy rays or heating, so that the cured product containing the curable epoxy resin composition can pass through The adhesive layer of the first layer sticks the transparent protective film to the polarizing film, or sticks the first retardation film to the polarizing film. As a method of applying the adhesive, for example, various coating methods such as knife coating, wire bar coating, die coating, comma coating, and gravure coating can be used.

The adhesive containing an epoxy resin used to bond the transparent protective film 102 and the first retardation film 103 containing an olefinic resin to the polarizing film 101 can basically be a solvent-free adhesive that does not contain a solvent component substantially. However, since there are various optimum viscosity ranges in each coating method, a solvent may be contained for viscosity adjustment. It is preferable to perform heat treatment or the like to remove the solvent used for viscosity adjustment after coating on the film and before curing the adhesive.

As the solvent, it is preferable to use a solvent that dissolves the epoxy resin composition well without degrading the optical properties of the polarizing film, for example, organic solvents such as hydrocarbons represented by toluene and esters represented by ethyl acetate .

When the adhesive is cured by irradiating active energy rays, the light source used is not particularly limited. For example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, etc. , black light, microwave excited mercury lamp, metal halide lamp, etc. The light irradiation intensity for irradiating the curable epoxy resin composition with light is determined for each target composition, and the irradiation intensity in the wavelength range effective for activation of the photocationic polymerization initiator is preferably 0.1 to 100 mW/cm ² . When the light irradiation intensity to the curable epoxy resin composition is less than 0.1mW/cm ² , the reaction time is too long, and when it exceeds 100mW/cm ² , due to heat from lamp radiation and the Heat generation may cause yellowing of the curable composition and deterioration of the polarizing film. The light irradiation time of the curable epoxy resin composition is controlled according to each composition to be cured, and it is not particularly limited. It is preferably set so that the cumulative light amount represented by the product of the irradiation intensity and the irradiation time is 10 to 5000 mJ/ cm ² .

When the cumulative amount of light irradiated to the curable composition is less than 10 mJ/cm ² , generation of active species derived from the photocationic polymerization initiator is insufficient, and curing of the adhesive layer may be insufficient. On the other hand, when the cumulative light amount exceeds 5000 mJ/cm ² , the irradiation time becomes very long, which is disadvantageous in improving productivity.

When polymerizing by heat, generally known methods can be used for heating, and the conditions are not particularly limited. The temperature at which cationic species and Lewis acid are generated by the cationic polymerization thermal initiator blended in the curable epoxy resin composition The above is heated, usually at about 50-200°C.

When curing is carried out under any conditions of irradiating active energy rays or heating, it is also preferable that the degree of polarization, the transmittance and the hue of the polarizing film, the transparency and the phase of the first retardation film containing the transparent protective film and the olefin-based resin Curing is performed in the range where the poor characteristics and various functions of the polarizing plate do not decrease.

[Second Retardation Film]

In the second retardation film 105, the core layer 31 contains a styrene-based resin, and the skin layers 32 made of a (meth)acrylic resin composition containing rubber particles are formed on both surfaces of the core layer.

The styrene-based resin constituting the core layer 31 may be a homopolymer of styrene or its derivatives, or a binary or more than binary copolymer of styrene or its derivatives and other copolymerizable monomers. . Here, the so-called styrene derivatives refer to compounds formed by bonding other groups to styrene, for example, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene Alkyl styrene, o-ethyl styrene, p-ethyl styrene, etc., hydroxystyrene, t-butoxy styrene, vinyl benzoic acid, o-chlorostyrene, p-chlorostyrene, etc. Substituted styrenes such as substituted styrenes in which hydroxyl groups, alkoxy groups, carboxyl groups, halogens, etc. are introduced into the benzene ring of styrene. Terpolymers disclosed in JP2003-50316-A and JP2003-207640-A may also be used. The styrene-based resin is preferably a copolymer of styrene or a styrene derivative, and at least one monomer selected from the group consisting of acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene. The styrene-based resin of the core layer is preferably made of a heat-resistant resin, and generally its Tg is 100°C or higher. The more preferable Tg of a styrene-type resin is 120 degreeC or more.

The core layer 31 containing a styrene-based resin preferably has a thickness of 10 to 100 μm. When the thickness is less than 10 μm, it may be difficult to express a sufficient retardation value by stretching. On the other hand, if the thickness exceeds 100 μm, the impact strength of the film tends to be weakened, and there is a tendency for the retardation value to increase due to external stress. When applied to a liquid crystal display device, white spots are likely to occur, and the display performance is likely to decline. .

The skin layer 32 disposed on both surfaces of the core layer 31 containing the above-mentioned styrene-based resin is composed of a (meth)acrylic resin composition in which rubber particles are mixed with a (meth)acrylic resin.

Here, as a (meth)acrylic-type resin, the homopolymer of an alkyl methacrylate or an alkyl acrylate, the copolymer of an alkyl methacrylate and an alkyl acrylate, etc. are mentioned, for example. As the alkyl methacrylate, specifically, methyl methacrylate, ethyl methacrylate, propyl methacrylate, etc. are mentioned, and as the alkyl acrylate, specifically, methyl acrylate ester, ethyl acrylate, propyl acrylate, etc. Among such (meth)acrylic resins, commercially available (meth)acrylic resins can be used. In addition, among the (meth)acrylic resins, there are compounds called impact-resistant (meth)acrylic resins, and there are also compounds called high Heat-resistant (meth)acrylic resin compound.

The rubber particles mixed with the (meth)acrylic resin are preferably acrylic rubber particles. Acrylic rubber particles are particles having rubber elasticity obtained by polymerizing alkyl acrylates such as butyl acrylate and 2-ethylhexyl acrylate as main components in the presence of polyfunctional monomers. Such particles having rubber elasticity may form a single layer, or may be a multilayer structure having at least one rubber elastic layer. As the acrylic rubber particle of multilayer structure, the following examples can be mentioned: the above-mentioned particle having rubber elasticity is used as a core, and the particle is covered with a hard alkyl methacrylate polymer; A hard alkyl methacrylate polymer is used as the core, and the above-mentioned acrylic polymer with rubber elasticity is used to cover the surrounding particles; The surrounding area is covered, and the surrounding area is covered with a hard alkyl methacrylate polymer, etc.

These rubber particles usually have an average particle diameter of about 50 to 400 nm in the elastic layer.

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 relative to 100 parts by weight of the (meth)acrylic resin. Since the (meth)acrylic resin and acrylic rubber particles are sold in a mixed state, commercially available products can be used. Examples of commercially available (meth)acrylic resins containing acrylic rubber particles include "HT55X" and "Technoloy (registered trademark) S001" sold by Sumitomo Chemical Corporation. Such a (meth)acrylic resin composition generally has a Tg of 160°C or lower, but preferably has a Tg of 120°C or lower, more preferably 110°C or lower.

The thickness of the skin layer 32 composed of a (meth)acrylic resin composition blended with rubber particles, preferably acrylic rubber particles, is preferably controlled to be 10 to 100 μm. When the thickness is less than 10 μm, film formation tends to be difficult. On the other hand, when the thickness is more than 100 μm, there is a tendency that the retardation value of the (meth)acrylic resin layer cannot be ignored.

As described above, in the second retardation film 105 used in the present invention, the core layer 31 containing a styrene-based resin preferably has a Tg of 120° C. The skin layer 32 made of the resin composition preferably has a Tg of 120°C or lower, more preferably 110°C or lower. It is preferable that the Tgs of both do not overlap, and that the core layer 31 containing a styrene-based resin has a higher Tg than the skin layer 32 composed of a (meth)acrylic resin composition containing rubber particles.

The second retardation film 105 used in the present invention can be produced by, for example, co-extruding a styrene-based resin and a (meth)acrylic resin composition containing rubber particles, followed by stretching. Alternatively, a method may be used in which a single-layer film is produced separately, thermally fused by thermal lamination, and then stretched.

In this second retardation film 105, a three-layer structure is formed, that is, a layer composed of a (meth)acrylic resin composition mixed with rubber particles is formed on both surfaces of the styrene-based resin core layer 31. Cortex 32 . In this three-layer structure, the skin layers 32 arranged on both surfaces are generally made to have approximately the same thickness. By forming a three-layer structure in this way, the skin layer 32 composed of a (meth)acrylic resin composition containing rubber particles functions as a protective layer, and thus has excellent mechanical strength and chemical resistance.

By stretching, an in-plane retardation can be imparted to the second retardation film 105 configured as described above. Stretching can be carried out by known longitudinal uniaxial stretching, stenter horizontal uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, etc., and stretching can be carried out in such a way as to obtain the required retardation value .

In the second retardation film 105 used in the present invention, it is preferable that the in-plane retardation value Re is 20 to 120 nm, and has a refractive index anisotropy in which the _Nz coefficient represented by the above formula (5) is greater than -2 and less than -0.5 .

When the first retardation film 103 and the second retardation film 105 are laminated, it is preferable that the change in the angle formed by the orientation angles of the first retardation film 103 and the second retardation film 105 is set to 0.4° within an interval of 10 cm. the following. When the change in the angle formed by the orientation angle is larger than 0.4°, the polarization state changes rapidly locally, and therefore color irregularities are observed when mounted on a liquid crystal display device. Here, the term "orientation angle" refers to the maximum orientation of the refractive index in each part of each film.

In a stretched film, the axis with the largest in-plane refractive index is generally called the slow axis. If you look closely, this axis varies slightly in each part, so such an orientation angle is also defined at the same time. The orientation angle can be measured using a commercially available retardation meter or detection device, for example, retardation film and optical material detection device RETS manufactured by Otsuka Electronics Co., Ltd., as shown in Examples described later. In order to reduce the change (deviation) of the angle formed by the orientation angles of the first retardation film 103 and the second retardation film 105 to the above-mentioned range, for example, preferably for the first retardation film 103 and the second retardation film 105 , each film having a small variation in the orientation angle was used.

[adhesive]

A first retardation film 103 containing an olefin-based resin and a second retardation film 105 are laminated through an adhesive 104. The retardation film 105 has a film containing a styrene-based resin sandwiched between skin layers 32, 32 containing an acrylic resin. The structure of both sides of the core layer 31 . The thickness of the 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 adhesiveness will decrease, and if it is too thick, troubles such as pressure-out of the pressure-sensitive adhesive will easily occur. The adhesive used to form the adhesive layer 104 can use a known adhesive, and is generally composed of the following composition, which uses acrylic resin, styrene resin, silicone resin, etc. as a base resin , a composition formed by adding cross-linking agents such as isocyanate compounds, epoxy compounds, and aziridine compounds, and silane coupling agents as needed.

[Liquid crystal display device]

By arranging the adhesive layer 108 on the outside of the second retardation film 105, the composite polarizing plate 100 having the above configuration can be bonded to a liquid crystal cell. Furthermore, it is a common practice to attach a spacer 109 to the outside of the adhesive layer 108 and pre-stick the adhesive layer 108 for protection before use. By laminating this composite polarizing plate 100 on at least one side of a liquid crystal cell, a liquid crystal display device can be constructed. When applied to a liquid crystal display device, the spacer 109 is peeled off first, and then the adhesive layer 108 can be used to stick to the liquid crystal unit.

The composite polarizing plate may be arranged on both sides of the liquid crystal cell, or the composite polarizing plate may be arranged on one side of the liquid crystal cell, and another polarizing film may be arranged on the other side. When bonding to a liquid crystal cell, it arrange|positions so that the retardation film side may face a liquid crystal cell.

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

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

As the material used in the transparent protective film that satisfies the points that the in-plane retardation value Re is 10 nm or less and the absolute value of the thickness direction retardation value Rth is 15 nm or less, cellulose-based resins, cyclic olefin-based resins, ( Meth)acrylic resins, ethylene terephthalate resins, acrylic resins, and the like.

【Example】

Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to these examples. In the examples, "parts" and "%" indicating usage-amount or content refer to a basis of weight unless otherwise specified. In addition, the film thickness, in-plane and thickness direction retardation values, and _Nz coefficient were measured by the following methods.

[measurement method of thickness]

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

[Measurement method of in-plane retardation value, thickness direction retardation value and N _z coefficient]

Using the phase difference meter KOBRA-21ADH manufactured by Oji Scientific Instruments Co., Ltd. based on the principle of the parallel-Nikkor rotation method, using light with a wavelength of 590 nm at 23°C, the in-plane retardation value Re, the thickness direction retardation value Rth, and the N _z coefficient To measure.

First, an example of manufacturing an adhesive, an adhesive, and a second retardation film comprising a styrene-based resin-containing core layer formed on both surfaces of Three-layer structure with a skin layer composed of a (meth)acrylic resin composition containing rubber particles.

[Preparation of water-based adhesive]

Dissolve 3 parts of carboxy-modified polyvinyl alcohol [KL-318 manufactured by Kuraray Co., Ltd.] in 100 parts of water, and add 1.5 parts of a polyamide epoxy-based additive as a water-soluble epoxy compound to the aqueous solution. Sumire-Zuresin 650 (30) manufactured by Chemtex Co., Ltd., an aqueous solution with a solid content concentration of 30%] was used to prepare a water-based adhesive.

[Preparation of Adhesive Consisting of Curable Epoxy Resin Composition]

100 parts of bis(3,4-epoxycyclohexylmethyl)adipic acid, 25 parts of diglycidyl ether of hydrogenated bisphenol A and 4,4'-bis(diphenyl 2.2 parts of sulfonium) diphenyl sulfide bis(hexafluorophosphate) were mixed, and defoaming was performed to obtain an adhesive composed of a curable epoxy resin composition.

In addition, the photocationic polymerization initiator was mixed with a 50% propylene carbonate solution.

[Preparation of acrylic adhesive]

In the copolymer of butyl acrylate and acrylic acid, urethane acrylate oligomer and isocyanate-based cross-linking agent are mixed, and an organic solvent solution is prepared, and the organic solvent solution is used with a die coater to obtain a thickness after drying. It was applied to the release-treated surface of a polyethylene terephthalate film (separator) having a thickness of 38 μm and dried to obtain an acrylic adhesive so as to reach a thickness of 25 μm.

[Manufacturing of the second retardation film with a three-layer structure]

(retardation film A)

A styrene-maleic anhydride copolymer resin (“DYLARK (registered trademark) D332” manufactured by Novachemical Co., Ltd., Tg=131° C.) was used as a core layer, and about 20% of acrylic rubber particles with an average particle diameter of 200 nm were blended. Methacrylic resin ("Technoloy (registered trademark) S001" manufactured by Sumitomo Chemical Co., Ltd., Tg=105° C.) was used as the skin layer, and three layers were co-extruded to obtain three layers of resin with skin layers formed on both sides of the core layer. membrane. This resin three-layer film was stretched to produce a retardation film having Re=47.3 nm and N _z coefficient=-1.06. Let this be retardation film A.

(retardation film B)

The same resin three-layer film as that used in the production of the aforementioned retardation film A was stretched to produce a retardation film with Re=47.3 nm and _Nz coefficient=-0.98. Let this be retardation film B.

(retardation film C)

The same resin three-layer film as that used in the production of the aforementioned retardation film A was stretched to produce a retardation film with Re=55.0 nm and _Nz coefficient=-1.1. Let this be retardation film C.

[Example 1]

(A) Fabrication of composite polarizing plate

A polyvinyl alcohol film with a thickness of 75 μm, which is composed of polyvinyl alcohol with an average degree of polymerization of about 2400 and a saponification degree of 99.9 mol % or more, is uniaxially stretched to about 5 times in a dry stretching method, and then the tension is maintained at 60 After immersing in pure water at °C for 1 minute, it was immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water at 28°C of 0.05/5/100 for 60 seconds. Thereafter, it was immersed for 300 seconds in an aqueous solution having a weight ratio of 8.5/8.5/100 of potassium iodide/boric acid/water at 72°C. Next, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizing film in which iodine was adsorbed and oriented to polyvinyl alcohol.

On one side of this polarizing film, a cellulose triacetate film with a thickness of 80 μm that has been saponified on the surface as a transparent protective film is attached, and on the other side, the following film is attached as a first retardation film, And make the absorption axis of the polarizing film parallel to the phase advancing axis of the first retardation film, thereby make the polarizing plate, what described film is the film that buys the thickness 38.6 μ n of Japan ZEON (strain) containing cyclic olefin resin , and Re=74.2nm, N _z coefficient=1.41. For lamination, the water-based adhesives described above were used, and after lamination, drying was carried out at 80° C. for 5 minutes, so that the transparent protective film and the first retardation film were adhered to the polarizing film. Then, the obtained polarizing plate was maintained under the condition of 40° C. for 168 hours.

Using an acrylic adhesive, the retardation film A shown above was attached to the first retardation film side of the polarizing plate obtained above in such a manner that the absorption axis of the polarizing film was parallel to the phase advance axis of the second retardation film as The second phase difference film, so as to make a composite polarizing plate.

(B) Production and evaluation of liquid crystal display devices

Remove the backlight plate from a liquid crystal display device [VIERA (Model: TH-37LZ85) manufactured by Panasonic Co., Ltd. manufactured by Panasonic Corporation] including an IPS mode liquid crystal cell, and then remove the polarizing plate arranged on the backlight plate side of the liquid crystal cell, and remove the glass Wash your face. Next, on the backlight side of the liquid crystal cell, the composite polarizing plate produced in the above (A) was bonded through an acrylic adhesive so that its absorption axis was the same as that of the originally arranged polarizing plate and the second phase The differential film is on the side of the liquid crystal cell to make a liquid crystal panel. Finally, the temporarily removed backlight panel is reassembled to form a liquid crystal display device.

For this liquid crystal display device, after turning on the backlight panel for 30 minutes, the distribution chart of the contrast ratio was measured using a liquid crystal viewing angle measuring device "EZ Contrast 88XL" manufactured by ELDIM, and is shown in FIG. 2 . In the figure, the numbers on the horizontal axis represent polar angles, and the numbers on the circumference represent azimuth angles. The distribution of contrast ratios is represented by the contrast ratios of the scales shown on the right, corresponding to the shades of white and black (the same is true for Figures 3 to 7). At an azimuth angle of 135° and a polar angle of 60° (circle in the figure), a contrast ratio of 192 is displayed. Here, the contrast ratio refers to the ratio of brightness in a white display state/brightness in a black display state. In addition, the azimuth angle takes the right direction of the screen as 0° and the counterclockwise rotation as a positive value, and the polar angle is an inclination angle from the normal direction of the screen.

[Example 2]

(A) Fabrication of composite polarizing plate

With respect to (A) of Example 1, the first retardation film of Example 1 was changed to a cyclic olefin-based resin with a thickness of 29.8 μm purchased from Japan ZEON Co., Ltd., Re=79.2nm, N _z Coefficient = 1.21 film, change the second retardation film to the retardation film B shown above, other similar operations to produce a composite polarizing plate, this retardation film B has both sides of the core layer containing styrene-based resin It has a three-layer structure with a skin layer composed of a (meth)acrylic resin composition containing rubber particles,

(B) Production and evaluation of liquid crystal display devices

Here, except having used the obtained composite polarizing plate, it carried out similarly to Example 1 (B), and produced the liquid crystal display device. This liquid crystal display device was measured by the same method as in (B) of Example 1, and the distribution graph of the contrast ratio is shown in FIG. 3 . At a position of 135° in azimuth and 60° in polar angle (circle in the figure), a contrast ratio of 195 is displayed.

[Example 3]

(A) Fabrication of composite polarizing plate and polarizing plate

In the same manner as in (A) of Example 2, a transparent protective film containing cellulose triacetate was attached to one side of the polarizing film, and a ring-containing protective film with Re=79.2nm and _Nz coefficient=1.21 was laminated on the other side. The first phase difference film of olefin-based resin and the phase difference film B are used to produce a composite polarizing plate. Three-layer structure of skin layer made of acrylic resin composition.

On the other hand, a cellulose triacetate film with a thickness of 80 μm that has been saponified on the surface was pasted on one side of the polarizing film produced by the method shown in the first half of (A) of Example 1, and on the other side, a cellulose triacetate film was pasted. A transparent protective film [KC4UEW manufactured by Konica Minolta Optical Co., Ltd.] containing cellulose triacetate with a thickness of 40 μm, Re=0.7nm, Rth=-0.1nm, and made of cellulose triacetate by lamination on both sides A transparent protective film for the polarizing plate. For lamination, the water-based adhesives shown above were used, and after lamination, they were dried at 80° C. for 5 minutes, so that the transparent protective films on both sides were adhered to the polarizing film.

(B) Production and evaluation of liquid crystal display devices

The backlight plate was removed from the liquid crystal display device including the same IPS mode liquid crystal cell used in (B) of Example 1, and the polarizing plates on both sides of the liquid crystal cell were removed, and the glass surfaces were washed. Next, on the backlight plate side of the liquid crystal cell, the composite polarizing plate shown in the first half of the above (A) is bonded through an acrylic adhesive so that the second retardation film is on the liquid crystal cell side, and the liquid crystal cell The polarizing plate shown in the second half of the above (A) is bonded through an acrylic adhesive so that the cellulose triacetate film with a thickness of 40 μm is on the side of the liquid crystal cell and each absorption axis is aligned with the original The absorption axes of the polarizing plates are the same to make a liquid crystal panel. Finally, the temporarily removed backlight panel is reassembled to form a liquid crystal display device.

This liquid crystal display device was measured by the same method as in (B) of Example 1, and the distribution graph of the contrast ratio is shown in FIG. 4 . At a position of 135° in azimuth and 60° in polar angle (circle in the figure), a contrast ratio of 195 is displayed.

[Example 4]

(A) Fabrication of composite polarizing plate and polarizing plate

In the same manner as (A) of Example 2, a transparent protective film containing cellulose triacetate was attached to one side of the polarizing film, and a cyclic olefin containing cyclic olefin with Re=79.2nm and N _z coefficient=1.21 was laminated on the other side. The first retardation film and the retardation film B of the base resin are used to produce a composite polarizing plate, and the retardation film B has (meth)acrylic acid containing rubber particles formed on both sides of the core layer containing the styrene-based resin. It is a 3-layer structure with a skin layer made of a resin composition.

On the other hand, on one side of the polarizing film produced by the method shown in the first half of (A) of Example 1, a saponified cellulose triacetate film with a thickness of 80 μm was attached on the surface, and on the other side, A transparent protective film of Re=2.1nm and Rth=2.8nm [purchased from Nippon Zeon Co., Ltd.] containing a cyclic olefin-based resin with a thickness of 40 μm was attached to produce a polarizing plate with transparent protective films laminated on both sides. For lamination, the water-based adhesives described above were used, and after lamination, drying was carried out at 80° C. for 5 minutes, so that the transparent protective film and the first retardation film were adhered to the polarizing film. Then, the obtained polarizing plate was maintained under the condition of 40° C. for 168 hours.

(B) Production and evaluation of liquid crystal display devices

The backlight plate was removed from the liquid crystal display device including the same IPS mode liquid crystal cell used in (B) of Example 1, and the polarizing plates on both sides of the liquid crystal cell were removed, and the glass surfaces were washed. Next, on the backlight plate side of this liquid crystal cell, the composite polarizing plate shown in the first half of the above-mentioned (A) is bonded through an acrylic adhesive so that the second retardation film is on the liquid crystal cell side, and on the liquid crystal cell side On the viewing side, the polarizing plate shown in the second half of the above (A) was bonded through an acrylic adhesive so that the protective film containing a cyclic olefin-based resin with a thickness of 40 μm was on the liquid crystal cell side and each absorption axis was aligned with the The absorption axes of the originally arranged polarizing plates were the same to fabricate a liquid crystal panel. Finally, the temporarily removed backlight panel is reassembled to form a liquid crystal display device.

This liquid crystal display device was measured by the same method as in (B) of Example 1, and the distribution graph of the contrast ratio is shown in FIG. 5 . At a position of 135° in azimuth and 60° in polar angle (circle in the figure), a contrast ratio of 195 is displayed.

[Comparative example 1]

(A) A cellulose triacetate film with a thickness of 80 μm that has been saponified on the surface is attached to one side of the polarizing film produced by the method shown in the first half of (A) of Production Example 1 of the Polarizing Plate, and on the other side A 40 μm-thick transparent protective film [KC4UEW manufactured by Konica Minolta Optical Co., Ltd.] containing cellulose triacetate, Re=0.7nm, Rth=-0.1nm, is laminated on both sides to produce triacetic acid Polarizing plate with a transparent protective film made of cellulose. For lamination, the respective water-based adhesives described above were used, and after lamination, they were dried at 80° C. for 5 minutes to adhere the transparent protective films on both sides to the polarizing film.

(B) Production and evaluation of liquid crystal display devices

Except having used the polarizing plate produced here, it carried out similarly to Example 1 (B), and produced the liquid crystal display device. This polarizing plate was glued to the liquid crystal cell with a cellulose triacetate film side having a thickness of 40 μm. This liquid crystal display device was measured by the same method as in (B) of Example 1, and the distribution graph of the contrast ratio is shown in FIG. 6 . At an azimuth angle of 135° and a polar angle of 60° (circle in the figure), a contrast ratio of 26 is displayed.

[Example 5]

(A) Fabrication of composite polarizing plate

With respect to (A) of Example 1, the first retardation film was changed to a 35.8 μm thick cycloolefin-based resin purchased from Japan ZEON Co., Ltd., Re=76.2nm, N _z coefficient=1.37 The second retardation film is changed to the retardation film C shown above, and the other is the same operation to make a composite polarizing plate. The retardation film C has the two sides of the core layer containing styrene resin. It has a three-layer structure with a skin layer composed of a (meth)acrylic resin composition containing rubber particles.

(B) Production and evaluation of liquid crystal display devices

Except having used the polarizing plate produced here, it carried out similarly to Example 1 (B), and produced the liquid crystal display device. This liquid crystal display device was measured by the same method as in (B) of Example 1, and the distribution graph of the contrast ratio is shown in FIG. 7 . At an azimuth angle of 135° and a polar angle of 60°, a contrast ratio of 326 is displayed.

In this liquid crystal display device, local color unevenness was observed in the display. Therefore, the composite polarizing plate used was peeled off from the liquid crystal panel, centered on the part where localized color unevenness was seen, and cut out along the width direction of the screen, the second retardation film having a three-layer structure and the cyclic olefin-containing The first retardation film of the resin-based resin was peeled off, and the orientation angle of the corresponding part was measured in each bonded state. The measurement was performed using the retardation film and optical material inspection device RETS manufactured by Otsuka Electronics Co., Ltd. along the This was performed over a span of 80 cm in the width direction of the screen, and the angle formed by the orientation angle of each site (difference between one orientation angle and the other orientation angle) was calculated. The results are shown in Fig. 8(a). The angle formed by the orientation angles of the two retardation films used here varies by a maximum of 0.43° at an interval of 10 cm.

(C) Production and evaluation of other composite polarizing plates and liquid crystal display devices

On the one hand, use the same grade as the film used as the first retardation film in (A) above, but other batches of film [purchased from Japan ZEON Co., Ltd. with a thickness of 35.8 μm containing cyclic olefin Resin film with Re=76.2nm and _Nz coefficient=1.37], other operations were the same as above (A) to prepare a composite polarizing plate, and a liquid crystal display device was assembled in the same manner as above (B) using this plate. The distribution of the contrast ratio of this liquid crystal display device is the same as that in FIG. 7 . At the position of the azimuth angle of 135° and the polar angle of 60°, a contrast ratio of 326 is displayed, and no local color spots are seen in the display. The composite polarizing plate used here was peeled off from the liquid crystal panel, and the same portion as when the orientation angle was measured was cut out along the screen width direction on the upper surface, and the second retardation film including a three-layer structure and the second retardation film containing a cyclic olefin-based resin were cut out. 1. The retardation film is peeled off, and the orientation angle of the corresponding part is measured in the respective bonded state. The measurement is made by using the retardation film and optical material inspection device RETS manufactured by Otsuka Electronics Co., Ltd., and along the width direction of the screen. It was carried out over a span of 80 cm, and the angle formed by the orientation angle of each site (difference between one orientation angle and the other orientation angle) was calculated. The results are shown in Fig. 8(b). The angle formed by the orientation angles of the two retardation films used here varies by a maximum of 0.27° at intervals of 10 cm.

Claims (10)

1. a composite polarizing plate is characterized in that,

On the face of first adhesive layer, be laminated with transparent protective film, on the another side of second adhesive layer, be laminated with first phase retardation film that contains the ethylene series resin at polarizing coating at polarizing coating,

And then, be laminated with second phase retardation film across adhesive phase in the outside of first phase retardation film,

Described second phase retardation film has 3-tier architecture, and described 3-tier architecture is the 3-tier architecture that is formed with the cortex that is formed by (methyl) acrylic resin composition that contains rubber particles on the two sides of the sandwich layer that contains phenylethylene resin series.

2. composite polarizing plate according to claim 1,

In first phase retardation film, length of delay is 30～150nm in the face, and has following refractive index anisotropy,, the refractive index of leading phase shaft direction and thickness direction in slow axis direction, the face in its face is made as n respectively that is _x, n _yAnd n _zThe time, formula: (n _x-n _z)/(n _x-n _y) defined N _zCoefficient greater than 1 less than 2,

In second phase retardation film, length of delay is 20～120nm in the face, and has following refractive index anisotropy, that is, and and Ding Yi N as mentioned above _zCoefficient greater than-2 less than-0.5.

3. composite polarizing plate according to claim 1 and 2, wherein, so that being mode below 0.4 °, the variation of the formed angle of the angle of orientation of first phase retardation film and second phase retardation film is laminated with first phase retardation film and second phase retardation film in the interval of 10cm.

4. according to each described composite polarizing plate in the claim 1～3, wherein, the ethylene series resin is the annular ethylene series resin that contains the structural unit of being derived by ester ring type alkene.

5. according to each described composite polarizing plate in the claim 1～3, second phase retardation film comprises sandwich layer and cortex, it is phenylethylene resin series more than 120 ℃ that described sandwich layer contains glass transition temperature, and described cortex is that (methyl) acrylic resin composition below 120 ℃ forms by glass transition temperature.

6. according to each described composite polarizing plate in the claim 1～5, wherein, second adhesive layer comprises the water system tackifier that contains polyvinyl alcohol resin and epoxy compound.

7. according to each described composite polarizing plate in the claim 1～5, wherein, second adhesive layer is formed by the solidfied material layer of epoxy based resin composition, and described epoxy based resin composition contains the irradiation that utilizes active energy ray or heating and the epoxy that solidifies is a resin.

8. composite polarizing plate according to claim 7, wherein, epoxy is that resin contains and has the compound that is bonded to the epoxy radicals of ester ring type ring more than 1 in the molecule.

9. IPS mode LCD, wherein, at least one face in IPS mode liquid crystal unit disposes each described composite polarizing plate in the claim 1～8.

10. IPS mode LCD according to claim 9; wherein a face in IPS mode liquid crystal unit disposes each described composite polarizing plate of claim 1～8; dispose the polarization plates that has transparent protective film in liquid crystal cell side at another side, described transparent protective film is that length of delay is that 10nm is following, the absolute value of thickness direction retardation value is the following transparent protective film of 15nm in the face.

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