JP2013003515A - Composite polarizer and liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite polarizer with an adhesive layer, which has a retardation film formed by laminating a skin layer made of a (meth)acrylic resin on both surfaces of a core layer and has an adhesive layer provided on a surface of the retardation film and has excellent adhesion between the retardation film and the adhesive layer and has moderate adhesiveness and reworkability for a glass substrate, and to provide a liquid crystal display device using the same.SOLUTION: The composite polarizer includes: a polarizing film; a transparent protection film laminated on one surface of the polarizing film; a first retardation film laminated on the other surface; a second retardation film formed by laminating a skin layer made of a (meth)acrylic resin on both surfaces of a core layer laminated on an outer surface of the first retardation film via a first adhesive layer; and a second adhesive layer laminated on an outer surface of the second retardation film. An IR spectrum of the second adhesive layer has a peak integral area ratio within a prescribed range, and adhesive force to glass of the second adhesive layer is 1.0 to 14.0 N/25 mm. The liquid crystal display device uses this composite polarizer.

Description

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

  As a polarizing plate widely used in liquid crystal display devices, a composite polarizing plate using a retardation film as one protective film laminated on a polarizing film is conventionally known. According to the composite polarizing plate, since one protective film of the polarizing plate can be omitted, the liquid crystal display device can be further reduced in thickness and weight.

  Along with the significant market expansion and spread of liquid crystal display devices in recent years, composite polarizing plates are required to have high durability that can withstand harsh usage environments, improved productivity, and improved visibility (particularly improved viewing angle characteristics). It has been. As a composite polarizing plate satisfying these required characteristics, Patent Document 1 has a first retardation film laminated on one surface of a polarizing film, and a styrene-based resin is formed on the first retardation film. A composite polarizing plate is disclosed in which a second retardation film having a three-layer structure in which a skin layer made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer is laminated. This composite polarizing plate is excellent in the viewing angle compensation ability of a liquid crystal display device (especially an IPS mode liquid crystal display device).

JP 2010-217870 A

  An adhesive is used when the composite polarizing plate described in Patent Document 1 is bonded to a liquid crystal cell. In order to prevent this adhesive from being peeled off from the second retardation film and causing defects in its appearance, or the visibility of the liquid crystal display device from being lowered, the second retardation film is used. On the other hand, high adhesion is required. On the other hand, once the composite polarizing plate is once bonded to the glass substrate of the liquid crystal cell, if there is any inconvenience, the composite polarizing plate breaks and the adhesive remains on the glass substrate surface (a part of the adhesive remains). Therefore, the glass substrate is required to have an appropriate adhesive strength and releasability (reworkability) so that the composite polarizing plate can be peeled off.

  As a method for improving the adhesion between the resin film and the pressure-sensitive adhesive layer, it is known to apply a corona treatment to the bonding surface, but the pressure-sensitive adhesive layer is applied to a (meth) acrylic resin layer such as the above skin layer. When pasting, sufficient adhesion effect could not be obtained even by corona treatment.

  An object of the present invention is to have a retardation film having a three-layer structure in which a skin layer made of a (meth) acrylic resin composition containing rubber particles is laminated on both surfaces of a core layer made of a styrene resin, and the surface thereof In the composite polarizing plate with the pressure-sensitive adhesive layer provided with the pressure-sensitive adhesive layer, the adhesive film has excellent adhesion between the retardation film and the pressure-sensitive adhesive layer, and has appropriate adhesiveness and releasability (reworkability) with respect to the glass substrate. It is to provide a composite polarizing plate and a liquid crystal display device using the same.

The present invention includes a polarizing film, a transparent protective film laminated on one surface of the polarizing film via a first adhesive layer, and a second adhesive layer laminated on the other surface of the polarizing film. A first retardation film made of an olefin-based resin, and a second position laminated on the surface opposite to the second adhesive layer in the first retardation film via the first pressure-sensitive adhesive layer. A phase difference film and a second pressure-sensitive adhesive layer laminated on a surface opposite to the first pressure-sensitive adhesive layer in the second phase difference film, and the second phase difference film is made of a styrene resin. It has a three-layer structure in which skin layers made of a (meth) acrylic resin composition containing rubber particles are laminated on both surfaces of the core layer, and the second pressure-sensitive adhesive layer has an infrared absorption spectrum represented by the following formula (1 ):
0.05 <S <0.20 (1)
Wherein, S is representative of the ratio S ₁ / S ₂ of the peak integrated area S ₂ at a wave number region of peak integrated area S ₁ and 1650～1800Cm ^-1 at a wave number region of 3550~3950cm ^-1]
And a composite polarizing plate having an adhesive strength to glass of 1.0 to 14.0 N / 25 mm.

The present invention also provides a liquid crystal display device comprising an IPS mode (lateral electric field mode) liquid crystal cell and the composite polarizing plate according to the present invention laminated on at least one surface thereof. The composite polarizing plate is bonded to the surface of the liquid crystal cell using the second pressure-sensitive adhesive layer. A liquid crystal display device according to one preferred embodiment is an IPS mode liquid crystal cell, the composite polarizing plate according to the present invention laminated on one surface thereof, and a polarizing plate laminated on the other surface, plane retardation value R _e in 590nm is at 10nm or less, and a polarizing plate having a transparent protective film absolute value is 15nm or less in the thickness direction retardation value R _th in the IPS liquid crystal cell side. The liquid crystal display device can include an ITO film between the IPS mode liquid crystal cell and the composite polarizing plate.

  According to the present invention, there is provided a composite polarizing plate having excellent adhesion between the skin layer and the pressure-sensitive adhesive layer of the second retardation film and having appropriate adhesion and releasability (reworkability) to the glass substrate. can do. In addition, the composite polarizing plate of the present invention includes a retardation film that is easy to produce, and exhibits excellent viewing angle characteristics when applied to a liquid crystal display device (especially an IPS mode liquid crystal display device). Furthermore, local color unevenness hardly occurs while two retardation films are laminated.

It is a schematic sectional drawing which shows an example of the laminated constitution of the composite polarizing plate which concerns on this invention.

<Composite polarizing plate>
FIG. 1 is a schematic cross-sectional view showing an example of a layer configuration of a composite polarizing plate according to the present invention. 1 includes a polarizing film 101; a transparent protective film 102 laminated on one surface of the polarizing film 101 via a first adhesive layer 106; a second film on the other surface of the polarizing film 101. A first retardation film 103 made of an olefin-based resin laminated through two adhesive layers 107; a first retardation film 103 on the surface opposite to the second adhesive layer 107 on the first side A second retardation film 105 laminated via the pressure-sensitive adhesive layer 104; and a liquid crystal cell or the like laminated on the surface opposite to the first pressure-sensitive adhesive layer 104 in the second retardation film 105; The 2nd adhesive layer 108 for bonding to another member is provided. The second retardation film 105 has a three-layer structure in which skin layers 32 and 32 made of a (meth) acrylic resin composition containing rubber particles are formed on both surfaces of a core layer 31 made of a styrene resin. . On the outside of the second pressure-sensitive adhesive layer 108, a separator 109 that temporarily protects the surface until bonding to another member is provided.

[Polarized film]
The polarizing film 101 is usually a step of uniaxially stretching a polyvinyl alcohol resin film by a known method, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, dichroism It is manufactured through a step of treating a polyvinyl alcohol resin film on which a dye is adsorbed with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

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

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

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. A polyvinyl alcohol-type resin can be formed into a film by a well-known method. The film thickness of the raw film is, for example, about 10 to 150 μm.

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

  In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a 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 the polyvinyl alcohol resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

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

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

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

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

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

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

  The moisture content of the polarizing film after the drying treatment is usually 5 to 20% by weight, and preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost and the film may be damaged or broken. If the moisture content exceeds 20% by weight, the thermal stability of the polarizing film may be inferior. Thus, the thickness of the polarizing film obtained by adsorbing and orienting the dichroic dye is usually about 5 to 40 μm.

[First retardation film made of olefin resin]
The first retardation film 103 disposed on the liquid crystal cell side of the polarizing film 101 is made of an olefin resin. The olefin resin is a chain aliphatic olefin such as ethylene and propylene, or a structural unit derived from an alicyclic olefin such as norbornene or a substituted product thereof (hereinafter collectively referred to as norbornene monomer). It becomes resin. The olefin resin may be a copolymer using two or more kinds of monomers.

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

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

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

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

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

  In addition, as the first retardation film 103, a film made of a mixed resin containing two or more types of olefin resins, or a film made of a mixed resin of an olefin resin and another thermoplastic resin can also be used. For example, examples of the mixed resin containing two or more types of olefin resins include a mixture of a cyclic olefin resin and a chain aliphatic olefin resin as described above. When a mixed resin of an olefin resin and another thermoplastic resin is used, another thermoplastic resin is appropriately selected depending on the purpose. Specific examples include polyvinyl chloride resin, cellulose resin, polystyrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, (meth) acrylic resin, polyvinyl acetate resin, polyvinyl chloride. Vinylidene resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyether Examples include ether ketone resins, polyarylate resins, liquid crystalline resins, polyamideimide resins, polyimide resins, polytetrafluoroethylene resins, and the like. A thermoplastic resin can be used individually by 1 type or in combination of 2 or more types. The thermoplastic resin may be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, and stereoregularity imparting.

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

  The olefin-based resin can be formed by a casting method from a solution, a melt extrusion method, or the like. When forming a film from two or more kinds of mixed resins, the film forming method is not particularly limited. For example, a film is formed by a casting method using a uniform solution obtained by stirring and mixing resin components with a solvent at a predetermined ratio. A production method, a method in which a resin component is melt-mixed at a predetermined ratio, and a film is produced by a melt extrusion method, and the like are employed.

  The film made of the olefin resin may contain other components such as a residual solvent, a stabilizer, a plasticizer, an anti-aging agent, an antistatic agent, and an ultraviolet absorber as necessary. Moreover, a leveling agent can also be contained in order to reduce the surface roughness.

The first retardation film 103, the in-plane slow axis direction, and the refractive index in the in-plane fast axis direction and the thickness direction respectively n _x, and n _y and n _z, when the thickness of the film is d, the following Formula (2):
_{R e = (n x -n y} ) × d (2)
In-plane retardation value R _e in the definition is the wavelength 590nm is 30 to 150 nm, the following formula (3):
Nz factor _{= (n x -n z) /} (n x -n y) (3)
It is preferable that the Nz coefficient defined by the above has a refractive index anisotropy of more than 1 and less than 2.

  The first retardation film having refractive index anisotropy as described above can be obtained by longitudinal uniaxial stretching, tenter transverse uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like of the film made of the olefin resin. In addition to adjusting the draw ratio and draw speed appropriately, the desired refractive index anisotropy can be selected by appropriately selecting various temperatures such as preheating temperature, drawing temperature, heat setting temperature, cooling temperature, etc. Sex can be obtained.

  The first retardation film 103 preferably has a thickness in the range of 20 to 80 μm, and more preferably in the range of 40 to 80 μm.

[Transparent protective film]
The transparent protective film 102 laminated on one surface of the polarizing film 101 is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. The material constituting such a transparent protective film is not particularly limited. For example, a (meth) acrylic resin having a methyl methacrylate resin as a representative example, and a chain olefin resin having a polypropylene resin as a representative example. , Cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, polyvinyl acetate resin, polyvinylidene chloride resin, Polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyamideimide resin Fat, and polyimide resin.

  The said resin can be used individually or in combination of 2 or more types. Further, the resin can be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between different polymers. Modifications such as mixing including cases may be mentioned.

  Among these, as the material for the transparent protective film 102, it is preferable to use a (meth) acrylic resin, a polyethylene terephthalate resin, a polypropylene resin, or a cellulose resin, typically a methyl methacrylate resin.

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

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

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

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

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

  Commercially available methyl methacrylate resins can be easily obtained. For example, “Sumipex” (manufactured by Sumitomo Chemical Co., Ltd.), “Acrypet” (manufactured by Mitsubishi Rayon Co., Ltd.), “Delpet” (manufactured by Asahi Kasei Co., Ltd.), “Parapet” (manufactured by Kuraray Co., Ltd.), “Acryviewer” (manufactured by Nippon Shokubai Co., Ltd.), and the like.

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

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

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

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

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

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

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

  Examples of a method for producing the transparent protective film 102 from the resins listed above include, for example, a solvent casting method in which a resin dissolved in a solvent is cast onto a metal band or drum, and the solvent is removed by drying to obtain a film. A melt extrusion method for obtaining a film by heating and kneading above the melting temperature, extruding from a die, and cooling is employed. In the melt extrusion method, a single layer film can be extruded or a multilayer film can be extruded simultaneously.

Examples of commercially available products that can be used as the transparent protective film 102 are as follows.
Methyl methacrylate resin film: Trade names “Technoloy” (manufactured by Sumitomo Chemical Co., Ltd.), “Acrylite”, “Acryprene” (manufactured by Mitsubishi Rayon Co., Ltd.), “Delagrass” (manufactured by Asahi Kasei Co., Ltd.), “Paragrass” ”,“ Comoglas ”(manufactured by Kuraray Co., Ltd.),“ Acribua ”(manufactured by Nippon Shokubai)
Polyethylene terephthalate resin film: Trade name "Novaclear" (Mitsubishi Chemical Corporation), "Teijin A-PET Sheet" (Teijin Chemicals Ltd.),
Polypropylene-based resin films: Trade name “FILMAX CPP film” (manufactured by FILMAX), “Santox” (manufactured by Sun Tox Co., Ltd.), “Tosero” (manufactured by Tosero Co., Ltd.), “Toyobo Pyrene Film” (Toyobo Co., Ltd.) Company), "Trephan" (manufactured by Toray Film Processing Co., Ltd.), "Nihon Polyace" (manufactured by Nippon Polyace),
Cellulose-based resin films: trade name “Fujitac TD” (manufactured by Fuji Film Co., Ltd.), “Konica Minolta TAC Film KC” (manufactured by Konica Minolta Opto Co., Ltd.).

  The transparent protective film 102 can be provided with antiglare properties (haze). Examples of a method for imparting antiglare properties include a method in which fine particles (inorganic fine particles or organic fine particles) are mixed into a raw material resin to form a film, one of which is constituted by a resin in which fine particles are mixed by multilayer extrusion, and the other To make a two-layer film composed of a resin in which fine particles are not mixed, or a method to make a three-layer film with a resin mixed with fine particles on the outside, by mixing fine particles with a curable binder resin on one side of the film For example, a method of coating a coating solution and curing the binder resin to provide an antiglare layer is employed.

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

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

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

  On the transparent protective film 102, functional layers such as a light diffusion layer, an antireflection layer, a low reflection layer, a hard coat layer, an antistatic layer, and an antifouling layer can be provided in addition to the antiglare layer.

  The thickness of the transparent protective film 102 is usually about 1 to 500 μm, preferably 10 to 200 μm, and more preferably 20 to 100 μm from the viewpoints of strength and handleability. When the thickness is within this range, the polarizing film is mechanically protected, and even when exposed to high temperature and high humidity, the polarizing film does not shrink and stable optical characteristics can be maintained.

[First Adhesive Layer and Second Adhesive Layer]
As a method of laminating the transparent protective film 102 and the first retardation film 103 on the polarizing film 101, a method of providing and integrating the first and second adhesive layers 106 and 107, respectively, is employed. Under the present circumstances, 0.1-35 micrometers is preferable and, as for the thickness of an adhesive bond layer, 0.1-15 micrometers is more preferable. If it is this range, a floating and peeling will not arise between the film and polarizing film which are laminated | stacked, and the adhesive force which does not have a practical problem will be obtained.

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

  One preferable adhesive for forming the first and second adhesive layers 106 and 107 is a water-based adhesive, and a typical example thereof is a polyvinyl alcohol-based resin as a main component. Examples of commercially available polyvinyl alcohol resins that can be used as water-based adhesives include “KL-318” manufactured by Kuraray Co., Ltd.

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

  Another preferred adhesive is an adhesive made of an epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating. When the adhesive is used, the adhesive between the films is applied by irradiating active energy rays or heating the adhesive layer interposed between the films to cure the curable epoxy resin contained in the adhesive. Can be done. Curing of the epoxy resin by irradiation with active energy rays or heating is preferably performed by cationic polymerization of the epoxy resin. In this specification, an epoxy resin means a compound having two or more epoxy groups in the molecule.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  Examples of the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes.

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

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

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

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

  Only one kind of the cationic photopolymerization initiator may be used alone, or two or more kinds thereof may be mixed and used. Among these, aromatic sulfonium salts are preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and thus can provide a cured product having excellent curability and good mechanical strength and adhesive strength.

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

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

  Specific examples of the photosensitizer include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o -Benzophenone derivatives such as methyl benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2 Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other α, α-diethoxyacetophenone, benzi Ru, fluorenone, xanthone, uranyl compounds, halogen compounds, and the like. A photosensitizer may be used individually by 1 type and may use 2 or more types together. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.

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

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

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

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

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

  In the curable epoxy resin composition, additives such as an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent are blended. Can do. Examples of the ion trapping agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixed inorganic compounds. The antioxidant is a hindered phenol-based antioxidant. Etc.

  After the adhesive comprising the curable epoxy resin composition as described above is applied to one or both adhesive surfaces of the films to be bonded, the adhesive is applied on the adhesive-coated surface, and the active energy is applied. The adhesive layer is cured by irradiating a wire or heating, and adhesion between films is made. As an adhesive coating method, for example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be adopted. In addition, prior to film bonding, it is preferable to perform easy adhesion treatment such as saponification treatment, corona treatment, or plasma treatment on one or both adhesion surfaces of the films to be laminated.

  The adhesive composed of the curable epoxy resin composition can basically be used as a solventless adhesive that does not substantially contain a solvent component, but each coating method has an optimum viscosity range. Therefore, a solvent may be included for viscosity adjustment. It is preferable to use a solvent that dissolves the epoxy resin composition well without degrading the optical performance of the polarizing film. For example, hydrocarbons represented by toluene, esters represented by ethyl acetate, and the like. And organic solvents such as

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

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

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

  The styrenic resin constituting the core layer 31 can be a homopolymer of styrene or a derivative thereof, or can be a binary or higher copolymer of styrene or a derivative thereof and another copolymerizable monomer. There can also be. Here, the styrene derivative is a compound in which another group is bonded to styrene, such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, o-ethylstyrene, Alkyl styrene such as p-ethyl styrene, hydroxy styrene, tert-butoxy styrene, vinyl benzoic acid, o-chloro styrene, p-chloro styrene, benzene nucleus of styrene, hydroxyl group, alkoxy group, carboxyl group, halogen Substituted styrene etc. in which etc. were introduced are mentioned. A terpolymer as disclosed in JP-A-2003-50316 and JP-A-2003-207640 can also be used. The styrene resin is preferably a copolymer of styrene or a styrene derivative and at least one monomer selected from acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene. The styrenic resin of the core layer 31 is preferably composed of a heat resistant material, and generally has a glass transition temperature Tg of 100 ° C. or higher. The more preferable Tg of the styrene resin is 120 ° C. or higher.

  The core layer 31 is preferably set so that its thickness is 10 to 100 μm. When the thickness is less than 10 μm, a sufficient retardation value may not easily be exhibited by stretching. On the other hand, if the thickness exceeds 100 μm, the impact strength of the film tends to be weak and the retardation change due to external stress tends to increase, and white spots are likely to occur when applied to a liquid crystal display device. Is prone to decline.

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

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

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

  The thickness of the skin layer 32 is preferably 10 to 100 μm. If the thickness is less than 10 μm, film formation tends to be difficult. On the other hand, when the thickness exceeds 100 μm, the retardation of the (meth) acrylic resin layer tends not to be negligible.

  As described above, the core layer 31 in the second retardation film 105 preferably has a Tg of 120 ° C. or higher, while the skin layer 32 has a Tg of 120 ° C. or lower, more preferably 110 ° C. or lower. Is preferred. It is preferable that the Tg of both layers does not overlap and the core layer 31 has a higher Tg than the skin layer 32.

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

  The second retardation film 105 has a three-layer structure in which the skin layers 32 are formed on both surfaces of the core layer 31. In this three-layer structure, the skin layers 32 arranged on both sides are usually set to substantially the same thickness. Thus, by setting it as a 3 layer structure, the skin layer 32 acts as a protective layer, and becomes excellent in mechanical strength and chemical resistance.

  The second retardation film 105 is provided with in-plane retardation by stretching. Stretching can be performed by longitudinal uniaxial stretching, tenter transverse uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like, and may be performed so as to obtain a desired retardation value.

The second retardation film 105, the in-plane retardation value at a wavelength of 590nm, which is defined by the formula (2) R _e is 20 to 120, Nz coefficient defined by the above formula (3) is greater than -2 , Preferably having a refractive index anisotropy of less than −0.5.

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

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

[First adhesive layer]
The first retardation film 103 and the second retardation film 105 are laminated via the first pressure-sensitive adhesive layer 104. The thickness of the 1st adhesive layer 104 is about 5-100 micrometers normally, Preferably it is 5-40 micrometers. If the pressure-sensitive adhesive layer is too thin, the tackiness is lowered, and if it is too thick, problems such as the pressure-sensitive adhesive protruding easily occur. As the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 104, a known pressure-sensitive adhesive having an acrylic resin, a styrene resin, a silicone resin, or the like as a base polymer can be used, among which transparency, weather resistance, An adhesive having an acrylic resin having excellent heat resistance as a base polymer is suitable.

  As the acrylic resin, for example, one kind of alkyl (meth) acrylate such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, or 2-ethylhexyl (meth) acrylate is used. Homopolymers, copolymers using two or more of these alkyl (meth) acrylates, and one or more alkyl (meth) acrylates and one or two other monomers. The copolymer used above is preferably used.

  Examples of other monomers copolymerizable with alkyl (meth) acrylate include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, Polar acrylic monomers having a polar group such as a carboxy group, a hydroxyl group, an amide group, an amine group, and an epoxy group, such as N-dimethylaminoethyl (meth) acrylate and glycidyl (meth) acrylate, are preferably used.

  The pressure-sensitive adhesive usually contains a crosslinking agent. Examples of the crosslinking agent include an isocyanate compound, an epoxy compound, and an aziridine compound. Adhesives include appropriate additives such as resins such as tackifier resins, antioxidants, ultraviolet absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors, photopolymerization initiators, and silane coupling agents. It can also be blended. Furthermore, fine particles can be included to impart light scattering properties.

  In addition, prior to the bonding of the first retardation film 103 and the second retardation film 105 using the first pressure-sensitive adhesive layer 104, a bonding surface of these retardation film and / or pressure-sensitive adhesive layer is used. Surface treatment such as corona treatment may be performed.

[Second adhesive layer]
The 2nd adhesive layer 108 laminated | stacked on the outer surface of the 2nd phase difference film 105 is an adhesive layer for bonding a composite polarizing plate to another member (mainly liquid crystal cell), The composition ( Regarding the base polymer, the cross-linking agent, other additives) and the thickness, the contents described for the first pressure-sensitive adhesive layer are cited. The second pressure-sensitive adhesive layer 108 has an infrared absorption (IR) spectrum represented by the following formula (1):
0.05 <S <0.20 (1)
Wherein, S is representative of the ratio S ₁ / S ₂ of the peak integrated area S ₂ at a wave number region of peak integrated area S ₁ and 1650～1800Cm ^-1 at a wave number region of 3550~3950cm ^-1]
It satisfies. By using the pressure-sensitive adhesive layer satisfying the above formula (1), excellent adhesion between the skin layer 32 made of the (meth) acrylic resin composition containing rubber particles and the second pressure-sensitive adhesive layer 108 is obtained. This can improve the durability of the composite polarizing plate. For example, even if it is subjected to a durability test that is exposed to a high temperature for a long time, the second pressure-sensitive adhesive layer is peeled off from the second retardation film, resulting in a defect in appearance, and the visibility of the liquid crystal display device is lowered. Can be suppressed or prevented.

In the infrared absorption spectrum, the absorption peak appearing in the wave number region of 3550 to 3950 cm ⁻¹ is due to the hydroxyl group. The absorption peak appearing in the wave number region of 1650-1800 cm ⁻¹ is attributed to the carbonyl group. The peak integrated area means the total area of absorption peaks appearing in the wave number region. The above formula (1) means that the ratio S of the integrated area S ₁ of the absorption peak due to the hydroxyl group to the integrated area S ₂ of the absorption peak due to the carbonyl group is more than 0.05 and less than 0.20. ing. Preferably they are 0.06 or more and 0.18 or less. When the peak integrated area ratio S is 0.05 or less, the adhesion between the skin layer 32 and the second pressure-sensitive adhesive layer 108 becomes insufficient. On the other hand, when the peak integrated area ratio S is 0.20 or more, the curing time at the time of preparing the pressure-sensitive adhesive may become long, which is not preferable from the viewpoint of productivity.

  The peak integrated area ratio S can be controlled, for example, by adjusting the hydroxyl group content of the base polymer of the pressure-sensitive adhesive. For example, the base polymer is an acrylic resin, and the content of the hydroxyl group-containing acrylic monomer constituting the acrylic resin is adjusted.

  Further, the second pressure-sensitive adhesive layer 108 has a glass adhesive strength of 1.0 to 14.0 N / 25 mm, preferably 1.0 to 10.0 N / 25 mm. By adjusting the adhesion to glass within this range, it is possible to impart an appropriate adhesion and releasability (reworkability) to the glass substrate of the liquid crystal cell. If the adhesive force to glass is less than 1.0 N / 25 mm, the adhesive force is too low and peeling between the glass substrate and the second adhesive layer is likely to occur. When the adhesive force to glass exceeds 14.0 N / 25 mm, the adhesive force is too high, and therefore, the composite polarizing plate breaks and the adhesive remains on the surface of the glass substrate during rework, and good reworkability cannot be obtained.

  The glass adhesive force of the second pressure-sensitive adhesive layer 108 can be controlled by adjusting the elasticity of the base polymer or adjusting the blending amount of an additive (for example, a silane coupling agent).

  Prior to the bonding of the second pressure-sensitive adhesive layer 108 and the second retardation film 105, a surface treatment such as a corona treatment may be performed on the bonding surface of the retardation film and / or the pressure-sensitive adhesive layer.

  Usually, a separator 109 is bonded to the outside of the second pressure-sensitive adhesive layer 108 to temporarily protect the second pressure-sensitive adhesive layer 108 until the composite polarizing plate is used. The separator 109 is not particularly limited as long as it is a release-treated plastic film, and for example, a film made of a transparent resin such as polyethylene terephthalate and subjected to a release treatment with a silicone resin or the like can be used.

<Liquid crystal display device>
The composite polarizing plate 100 according to the present invention is laminated on at least one side of the liquid crystal cell to constitute a liquid crystal display device. When applied to a liquid crystal display device, the separator 109 is peeled off and then bonded to the liquid crystal cell by the second pressure-sensitive adhesive layer 108. The composite polarizing plate according to the present invention can be arranged on both sides of the liquid crystal cell, or the composite polarizing plate can be arranged on one side of the liquid crystal cell and another polarizing plate can be arranged on the other side. The liquid crystal display device having the latter configuration is particularly effective when the liquid crystal cell is in the IPS mode (lateral electric field mode).

When placing the composite polarizing plate of the present invention on one side of the liquid crystal cell, on the other surface, plane retardation value R _e at a wavelength of 590nm is at 10nm or less, and the following formula (4):
_Rth = [( _nx + _ny ) / 2- _nz ] * d (4)
The absolute value of a thickness direction retardation value R _th THAT defined it is preferred that the transparent protective film is 15nm or less disposing the polarizing plates having the liquid crystal cell side. The liquid crystal cell-side transparent protective film of the polarizing plate more preferably has an R _e of 5 nm or less and an absolute value of R _th of 10 nm or less. Such a configuration is extremely advantageous for improving the viewing angle characteristics of the IPS mode liquid crystal display device.

Plane retardation value R _e is not less 10nm or less, as a material used for the transparent protective film in which the absolute value of a thickness direction retardation value R _th satisfies the requirement that 15nm or less, for example, cellulose resins, cyclic olefin resins, (meth ) Acrylic resin, polyethylene terephthalate resin, polypropylene resin and the like.

In the case of an IPS mode liquid crystal display device, an antistatic translucent conductive film may be interposed between the IPS mode liquid crystal cell and the polarizing plate. Examples of the light-transmitting conductive film include an ITO (Indium-Tin-Oxide) film, a SnO ₂ film, an In ₂ O ₃ film, etc. Among them, an ITO film is preferable. For example, the composite polarizing plate according to the present invention is used for the polarizing plate disposed on the viewing side of the IPS liquid crystal cell, and a light-transmitting conductive film such as an ITO film is interposed between the IPS mode liquid crystal cell and the composite polarizing plate. A form can be adopted. In this case, the translucent conductive film is a liquid crystal layer on a transparent substrate farther from the backlight of an IPS mode liquid crystal cell composed of two transparent substrates (glass substrates) arranged to face each other with the liquid crystal layer interposed therebetween. The composite polarizing plate is bonded onto the translucent conductive film. The composite polarizing plate of the present invention can have appropriate adhesive strength and reworkability even for such a light-transmitting conductive film.

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

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

(In-plane retardation value and Nz coefficient)
Using a phase difference meter for Oji Scientific Instruments Co. parallel Nicols rotation method the principle of "KOBRA-21ADH" was measured in-plane retardation value R _e and Nz coefficient at a wavelength of 590nm at 23 ° C..

(Peak integrated area ratio S)
Using a FT-IR “640-IR” manufactured by VARIAN Co., Ltd., an IR spectrum of a sheet-like adhesive (adhesive layer) was obtained at 23 ° C., and a peak integrated area S ₁ in a wave number region of 3550 to 3950 cm ^−1. And the ratio S ₁ / S ₂ between the peak integrated area S ₂ in the wave number region of 1650 to 1800 cm ⁻¹ was calculated, and this was used as the peak integrated area ratio S.

(Adhesion to glass)
The composite polarizing plate was cut into a size of 25 mm × 200 mm so that the absorption axis of the polarizing film was parallel to the long side, and used as an evaluation sample. The sample for evaluation was bonded to an alkali-free glass plate (“Eagle-XG” manufactured by Corning Co., Ltd.) on the second pressure-sensitive adhesive layer side, and then in an autoclave at a temperature of 50 ° C. and a pressure of 5 MPa for 20 minutes. The pressure treatment was performed, and the mixture was then left for 1 day in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%, and then autograph (“AGS-50NX” manufactured by Shimadzu Corporation) was used at a temperature of 23 ° C. and a relative humidity. Under the environment of 60%, one end in the length direction of the sample for evaluation was grasped, a 180 ° peel test was conducted at a peel speed of 300 mm / min, and the stress at the time of peel was measured to obtain the adhesion to glass.

<Example 1>
(1) Production of second retardation film Styrene-maleic anhydride copolymer resin [Dylark D332 manufactured by Nova Chemical Co., Ltd. (trade name), Tg = 131 ° C.] as a core layer, acrylic having an average particle diameter of 200 nm Three-layer coextrusion with a methacrylic resin (Sumitomo Chemical Co., Ltd. “Technoloy S001” (trade name), Tg = 105 ° C.) containing about 20% of rubber particles is used as a skin layer. A laminated film having a three-layer structure in which a skin layer was formed was obtained. The laminated film was stretched to obtain a second retardation film having a thickness of 46.0 μm. Each plane retardation value R _e, the Nz coefficient 60.0Nm, was -1.0.

(2) Bonding of second retardation film and second pressure-sensitive adhesive layer Sheet-shaped pressure-sensitive adhesive A was prepared as a second pressure-sensitive adhesive layer. The sheet-like pressure-sensitive adhesive A is a pressure-sensitive adhesive having an acrylic copolymer as a base polymer, and the copolymer component of the base polymer contains a hydroxyl group-containing acrylic monomer. The sheet integrated pressure-sensitive adhesive A had a peak integrated area ratio S and a glass adhesive strength of 0.10 and 1.4 N / 25 mm, respectively.

  Corona treatment equipment (corona surface treatment frame “STR-1764” manufactured by Kasuga Electric Co., Ltd., high-frequency power supply “CT-0212” and high-pressure on each bonding surface of the second retardation film and the sheet-like adhesive A Using a transformer “CT-T02W”, the corona discharge treatment was performed under the conditions of an output of 280 W and a line speed of 10 m / min, and then the second retardation film and the sheet-like adhesive A were bonded together.

(3) Preparation of aqueous adhesive 3 parts of carboxyl group-modified polyvinyl alcohol (“KL-318” manufactured by Kuraray Co., Ltd.) is dissolved in 100 parts of water, and a polyamide epoxy which is a water-soluble epoxy compound is dissolved in the aqueous solution. 1.5 parts of a system additive (Sumirez resin 650 (30), manufactured by Sumika Chemtex Co., Ltd., aqueous solution with a solid content concentration of 30%) was added to obtain an aqueous adhesive.

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

(5) Production of Composite Polarizing Plate A 80 μm thick triacetylcellulose film having a surface subjected to saponification treatment is pasted as a transparent protective film on one side of the polarizing film, and the first side is provided on the other side. As the retardation film, a retardation film (R _e = 90 nm, Nz coefficient = 1.4) made of a cyclic olefin resin having a thickness of 25 μm obtained from Nippon Zeon Co., Ltd. is used. The retardation films were bonded so that the fast axes were parallel. For the bonding, the above-described aqueous adhesive was used, and after the bonding, the transparent protective film and the first retardation film were adhered to the polarizing film by drying at 80 ° C. for 5 minutes. After the adhesion, it was cured at 40 ° C. for 168 hours.

  Next, the second retardation film with the second pressure-sensitive adhesive layer shown above is disposed on the first retardation film side through the first pressure-sensitive adhesive layer that is an acrylic pressure-sensitive adhesive layer. And a second retardation film were bonded so that the fast axes were parallel to each other to prepare a composite polarizing plate.

<Comparative Example 1>
A composite polarizing plate was produced in the same manner as in Example 1 except that instead of the sheet-like adhesive A, the sheet-like adhesive B, which was an acrylic adhesive, was used as the second adhesive layer. The peak integrated area ratio S of the sheet-like pressure-sensitive adhesive B and the glass adhesive strength were 0.00 and 17.5 N / 25 mm, respectively.

<Comparative example 2>
A composite polarizing plate was produced in the same manner as in Example 1 except that the sheet-like adhesive C was used in place of the sheet-like adhesive A as the second adhesive layer. The sheet-like pressure-sensitive adhesive C is a pressure-sensitive adhesive having an acrylic copolymer as a base polymer, and the copolymer component of the base polymer contains a hydroxyl group-containing acrylic monomer. The peak integrated area ratio S of the sheet-like pressure-sensitive adhesive C and the glass adhesive strength were 0.03 and 3.0 N / 25 mm, respectively.

<Comparative Example 3>
As the second pressure-sensitive adhesive layer, a sheet-like pressure-sensitive adhesive C is used instead of the sheet-like pressure-sensitive adhesive A, and the corona treatment conditions at the time of bonding the second retardation film and the sheet-like pressure-sensitive adhesive C are output 450 W, line A composite polarizing plate was produced in the same manner as in Example 1 except that the speed was 10 m / min.

The following evaluation test was performed on the obtained composite polarizing plate.
(A) Reworkability test The composite polarizing plate was cut into a size of 150 mm × 200 mm so that the absorption axis of the polarizing film was parallel to the long side, and used as an evaluation sample. The sample for evaluation was bonded to an alkali-free glass plate (“Eagle-XG” manufactured by Corning Co., Ltd.) on the second pressure-sensitive adhesive layer side, and then in an autoclave at a temperature of 50 ° C. and a pressure of 5 MPa for 20 minutes. Pressurized, and then left for 1 day in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60% A peel test in which the sample for evaluation is grasped by one end in the length direction and the sample for evaluation is peeled off from the alkali-free glass plate. The reworkability was evaluated according to the following criteria, and the results are shown in Table 1.

A: It was possible to peel off with an appropriate force, and there was no adhesive residue on the alkali-free glass plate.
B: The adhesive force between the second pressure-sensitive adhesive layer and the alkali-free glass plate was too strong, and the evaluation sample was broken and could not be peeled off.

(B) Durability test The composite polarizing plate was cut into a size of 150 mm × 200 mm so that the absorption axis of the polarizing film was parallel to the long side, and used as an evaluation sample. The sample for evaluation was bonded to an alkali-free glass plate (“Eagle-XG” manufactured by Corning Co., Ltd.) on the second pressure-sensitive adhesive layer side, and then in an autoclave at a temperature of 50 ° C. and a pressure of 5 MPa for 20 minutes. Pressurized, and then allowed to stand for 1 day in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%, followed by a durability test for 500 hours in a high-temperature tank set at 85 ° C. The results are shown in Table 1.

A: Peeling between the second retardation film and the second pressure-sensitive adhesive layer was not recognized, and a good appearance was maintained.
B: Peeling was recognized between the second retardation film and the second pressure-sensitive adhesive layer.

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

Claims (4)

A polarizing film;
A transparent protective film laminated on one surface of the polarizing film via a first adhesive layer;
A first retardation film made of an olefin resin laminated on the other surface of the polarizing film via a second adhesive layer;
A second retardation film laminated on the surface opposite to the second adhesive layer in the first retardation film via a first pressure-sensitive adhesive layer;
A second pressure-sensitive adhesive layer laminated on a surface opposite to the first pressure-sensitive adhesive layer in the second retardation film;
Including
The second retardation film has a three-layer structure in which a skin layer made of a (meth) acrylic resin composition containing rubber particles is laminated on both surfaces of a core layer made of a styrene resin,
The second pressure-sensitive adhesive layer has an infrared absorption spectrum represented by the following formula (1):
0.05 <S <0.20 (1)
Wherein, S is representative of the ratio S ₁ / S ₂ of the peak integrated area S ₂ at a wave number region of peak integrated area S ₁ and 1650～1800Cm ^-1 at a wave number region of 3550~3950cm ^-1]
And a composite polarizing plate having an adhesive strength to glass of 1.0 to 14.0 N / 25 mm.   A liquid crystal display device comprising: an IPS mode liquid crystal cell; and the composite polarizing plate according to claim 1, which is bonded to at least one surface of the IPS mode liquid crystal cell by the second pressure-sensitive adhesive layer. An IPS mode liquid crystal cell;
The composite polarizing plate according to claim 1, which is bonded to one surface of the IPS mode liquid crystal cell by the second pressure-sensitive adhesive layer,
A polarizing plate laminated on the other surface of the IPS mode liquid crystal cell, the transparent protective film having an in-plane retardation value at a wavelength of 590 nm of 10 nm or less and an absolute value of a thickness direction retardation value of 15 nm or less. A polarizing plate on the mode liquid crystal cell side;
A liquid crystal display device comprising:   The liquid crystal display device according to claim 2, wherein an ITO film is provided between the IPS mode liquid crystal cell and the composite polarizing plate.

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