WO2009119435A1 - Composite polarizing plate, method for producing composite polarizing plate, and liquid crystal display device using the same - Google Patents

Composite polarizing plate, method for producing composite polarizing plate, and liquid crystal display device using the same Download PDF

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WO2009119435A1
WO2009119435A1 PCT/JP2009/055415 JP2009055415W WO2009119435A1 WO 2009119435 A1 WO2009119435 A1 WO 2009119435A1 JP 2009055415 W JP2009055415 W JP 2009055415W WO 2009119435 A1 WO2009119435 A1 WO 2009119435A1
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WIPO (PCT)
Prior art keywords
film
polarizing plate
layer
adhesive
composite polarizing
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PCT/JP2009/055415
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French (fr)
Japanese (ja)
Inventor
寿和 松本
基淵 申
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住友化学株式会社
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Priority claimed from JP2008104669A external-priority patent/JP2009258226A/en
Priority claimed from JP2008208099A external-priority patent/JP2009258589A/en
Application filed by 住友化学株式会社 filed Critical 住友化学株式会社
Publication of WO2009119435A1 publication Critical patent/WO2009119435A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/28—Adhesive materials or arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2413/00—Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates
    • G02F2413/02—Number of plates being 2

Definitions

  • the present invention relates to a composite polarizing plate in which a transparent protective film is bonded to one side of a polarizing film and a retardation film is bonded to the other side.
  • a composite polarizing plate excellent in adhesiveness between a (meth) acrylic resin and a polarizing film used for a skin layer of a retardation film having a three-layer structure in which a core layer is sandwiched between skin layers, and a liquid crystal display using the same It relates to the device.
  • Liquid crystal display devices are used in various display devices by taking advantage of features such as low power consumption, low voltage operation, light weight and thinness.
  • the liquid crystal display device is composed of many materials such as a liquid crystal cell, a polarizing plate, a retardation film, a condensing sheet, a diffusion film, a light guide plate, and a light reflecting sheet. Therefore, improvements aimed at productivity, weight reduction, brightness improvement, and the like have been actively performed by reducing the number of constituent films or reducing the thickness of the film or sheet.
  • thermoplastic resin It is known that the heat resistance of a styrene resin can be improved by copolymerizing a monomer that forms a resin having a high glass transition temperature (hereinafter sometimes abbreviated as Tg), such as norbornene or maleic anhydride.
  • Tg glass transition temperature
  • mechanical strength and chemical resistance are not sufficient.
  • the thickness of the second adhesive layer is preferably 1 to 40 ⁇ m. According to the present invention, there is provided a liquid crystal display device in which the composite polarizing plate is disposed on at least one surface of a liquid crystal cell. Here, the composite polarizing plate is disposed so that the retardation film side faces the liquid crystal cell.
  • the core layer 31 made of styrene-based resin is desirably set so that its thickness is 10 to 100 ⁇ m. If the thickness is less than 10 ⁇ m, a sufficient retardation value may not easily be exhibited by stretching. On the other hand, if the thickness exceeds 100 ⁇ m, 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. Display performance is likely to deteriorate.
  • the thickness of the skin layer 32 made of a (meth) acrylic resin composition containing rubber particles, preferably acrylic rubber particles, is preferably 10 to 100 ⁇ m. When the thickness is less than 10 ⁇ m, film formation tends to be difficult. On the other hand, when the thickness exceeds 100 ⁇ m, the retardation of the (meth) acrylic resin layer tends to be ignorable.
  • the retardation film 30 configured as described above is given in-plane retardation by stretching. Stretching can be performed by well-known longitudinal uniaxial stretching, tenter lateral uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, etc., and may be performed so as to obtain a desired retardation value.
  • the transparent protective film 20 laminated on one surface of the polarizing film 10 is preferably one that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like.
  • Examples of the material for forming the transparent protective film 20 include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as diacetyl cellulose and triacetyl cellulose, (meth) acrylic resins such as polymethyl methacrylate, and polystyrene.
  • styrene resins such as acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, acrylonitrile / ethylene / styrene copolymer, styrene / maleimide copolymer, styrene / maleic anhydride copolymer, polycarbonate resin Etc.
  • cyclic olefin resins such as norbornene resins, olefin resins such as polyethylene, polypropylene, and propylene / ethylene copolymers, vinyl chloride resins, amide resins such as nylon and aromatic polyamide, aromatic polyimide, Imide resins such as polyimide amide, sulfone resins, polyether sulfone resins, polyether ether ketone resins, polyphenylene sulfide resins, vinyl alcohol resins, vinylidene chloride resins, vinyl butyral resins, polyoxymethylene resins An epoxy resin can be used, and a polymer film made of a blend of these resins can also be used as the transparent protective film 20.
  • the transparent protective film 20 is preferably subjected to saponification treatment, corona treatment, plasma treatment and the like prior to bonding with the polarizing film 10.
  • Epoxy resin composition The epoxy resin composition used for forming the second adhesive layer is typically a solventless resin composition containing the curable epoxy resin as a main component. is there. Such an adhesive can bond the polarizing film and the retardation film with sufficiently high adhesive strength, thereby obtaining a composite polarizing plate having excellent weather resistance. Adhesion between the polarizing film and the retardation film is performed by irradiating an activation energy ray or heating the coating layer of the adhesive interposed between the films, and a curable epoxy system contained in the adhesive. This can be done by curing the resin. In the present invention, the curing of the epoxy resin by activation energy ray irradiation or heat is preferably performed by cationic polymerization of the epoxy resin. In the present invention, the epoxy resin means a compound having two or more epoxy groups in the molecule.
  • an epoxy resin that does not contain an aromatic ring in the molecule is used from the viewpoint of weather resistance, refractive index, cationic polymerization, and the like.
  • examples of such epoxy resins include hydrogenated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.
  • the hydrogenated epoxy resin can be obtained by subjecting an aromatic epoxy resin to a nuclear hydrogenation reaction selectively under pressure in the presence of a catalyst.
  • aromatic epoxy resin 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, hydroxybenzaldehyde Examples include novolak-type epoxy resins such as phenol novolac epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and epoxidized polyvinylphenol. Among them, it is preferable to use hydrogenated bisphenol A glycidyl ether as the hydrogenated epoxy resin.
  • the alicyclic epoxy resin means an epoxy resin having at least one epoxy group bonded to the alicyclic ring in the molecule.
  • the “epoxy group bonded to an alicyclic ring” is a group having a structure in which one or a plurality of hydrogen atoms are removed from (CH 2 ) m in the structure represented by the following formula. In the following formula, m is an integer of 2 to 5.
  • a compound having 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.
  • the alicyclic epoxy resin preferably used in the present invention is specifically exemplified below, it is not limited to these compounds.
  • R 1 and R 2 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • R 11 and R 12 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • R 13 and R 14 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • VIII Vinylcyclohexene diepoxides represented by the following formula (VIII):
  • R 15 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • R 15 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • R 16 and R 17 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • R 18 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • R 18 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
  • aliphatic epoxy resin examples include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Examples include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, propylene Polyglycidyl of a polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as diglycidyl ether of glycol, ethylene glycol, propylene glycol or glycerin Examples include ether.
  • the epoxy equivalent of the epoxy resin used in the present invention is usually in the range of 30 to 3,000 g / equivalent, preferably 50 to 1,500 g / equivalent.
  • 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.
  • the compatibility with other components contained in the adhesive may be lowered.
  • cationic polymerization is preferably used as the curing reaction of the curable epoxy resin composition.
  • a cationic polymerization initiator it is preferable to mix
  • the cationic polymerization initiator generates a cationic species or a Lewis acid by irradiating or heating an activation energy ray such as visible light, ultraviolet ray, X-ray, electron beam, etc., and starts an epoxy group polymerization reaction.
  • an activation energy ray such as visible light, ultraviolet ray, X-ray, electron beam, etc.
  • a cationic polymerization initiator that generates a cationic species or Lewis acid upon irradiation of activation energy rays and initiates a polymerization reaction of an epoxy group is called a “photo cationic polymerization initiator”, and generates a cationic species or Lewis acid by heat.
  • the cationic polymerization initiator that initiates the polymerization reaction of the epoxy group is referred to as a “thermal cationic polymerization initiator”.
  • Photocationic polymerization initiator The method of curing the adhesive by irradiating with an activation energy ray using a cationic photopolymerization initiator enables curing at room temperature, reducing the need to consider the heat resistance of the polarizing film or distortion due to expansion. This is advantageous in that the phase difference film and the polarizing film can be favorably bonded.
  • the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy resin.
  • the photocationic polymerization initiator is not particularly limited, and examples thereof include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, and iron-allene complexes.
  • aromatic diazonium salt examples include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, benzenediazonium hexafluoroborate, and the like.
  • aromatic iodonium salt examples include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.
  • aromatic sulfonium salt examples include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis (diphenylsulfonio) diphenyl sulfide bis ( Hexafluorophosphate), 4,4'-bis (di ( ⁇ -hydroxyethoxy) phenylsulfonio) diphenyl sulfide, bis (hexafluoroantimonate), 4,4'-bis (di ( ⁇ -hydroxyethoxy) phenylsulfonio ) Diphenyl sulfide bis (hexafluorophosphate), 7- (di (p-toluyl) sulfonio) -2-isopropylthioxanthone hexafluor
  • iron-allene complex examples include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) methanide and the like.
  • Each of these photocationic polymerization initiators may be used alone or in combination with one or more other types.
  • aromatic sulfonium salts are preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.
  • the amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less with respect to 100 parts by weight of the curable epoxy resin.
  • the amount is less than 0.5 parts by weight per 100 parts by weight of the epoxy resin, curing becomes insufficient, and mechanical strength and adhesive strength tend to decrease.
  • the amount exceeds 20 parts by weight per 100 parts by weight of the epoxy resin, the ionic substance in the cured product increases, so that the hygroscopic property of the cured product increases and the durability performance may be reduced. It is not preferable.
  • photosensitizers include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, ⁇ , ⁇ -dimethoxy- ⁇ -phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate Benzophenone derivatives such as 4,4′-bis (dimethylamino) benzophenone and 4,4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2-chloroanthraquinone, 2-methyl Anthraquinone derivatives such as anthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; others, ⁇ , ⁇ -diethoxyacetophenone, benzyl, fluorenone, xanthone
  • each of these photosensitizers may be used alone, or may be used as a mixture with another one or more.
  • the photosensitizer is preferably contained within a range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.
  • thermal cationic polymerization initiator examples include benzylsulfonium salt, thiophenium salt, thioranium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide.
  • thermal cationic polymerization initiator examples include benzylsulfonium salt, thiophenium salt, thioranium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide.
  • These initiators can be easily obtained as commercial products.
  • “ADEKA OPTON CP77” and “ADEKA OPTON CP66” manufactured by ADEKA, Inc.
  • CI-2539 are trade names.
  • 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 used as an adhesive in the present invention 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 oxetane compounds can be easily obtained as commercial products.
  • oxetane compounds are trade names such as “Aron oxetane (registered trademark) OXT-101”, “Aron oxetane (registered trademark) OXT-121”, “Aron Oxetane (registered trademark) OXT-211”, “Aron Oxetane (registered trademark) OXT-221”, “Aron Oxetane (registered trademark) OXT-212” (above, manufactured by Toagosei Co., Ltd.) .
  • These oxetane ring-containing compounds are generally used in a proportion of 5 to 95% by weight, preferably 30 to 70% by weight, in the curable epoxy resin composition.
  • polyols those having no acidic groups other than phenolic hydroxyl groups are preferable.
  • 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.
  • the blending amount of these polyols is usually 50% by weight or less, preferably 30% by weight or less in the epoxy resin composition.
  • the curable epoxy resin composition has other additives such as an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic as long as the effects of the present invention are not impaired.
  • Resins, fillers, flow regulators, plasticizers, antifoaming agents, and the like can be blended.
  • the ion trapping agent include powdery bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based and mixed compounds thereof.
  • the antioxidant include hinders. Examples include dophenol antioxidants.
  • the thickness of the second adhesive layer is usually 50 ⁇ m or less, preferably 20 ⁇ m or less, and more preferably 10 ⁇ m or less.
  • the light source used is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, such as a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, An ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, or the like can be used.
  • the light irradiation intensity to the curable epoxy resin composition may vary from composition to composition, but the irradiation intensity in the wavelength region effective for activating the photocationic polymerization initiator is 0.1 to 100 mW / cm 2 . It is preferable.
  • the reaction time becomes too long, and when it exceeds 100 mW / cm 2 , the heat radiated from the lamp and the curable epoxy system
  • the heat generated during polymerization of the resin composition may cause yellowing of the curable epoxy resin composition and deterioration of the polarizing film.
  • the light irradiation time to the curable epoxy resin composition is controlled for each composition and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 10 times. It is preferably set to be 5,000 mJ / cm 2 .
  • polymerization When polymerization is carried out by heat, it can be heated by a generally known method, and the conditions thereof are not particularly limited, but usually a thermal cationic polymerization initiator blended in the curable epoxy resin composition is used. Heating is performed at a temperature higher than the temperature at which cationic species and Lewis acid are generated, and it is usually performed at 50 to 200 ° C.
  • the high elastic pressure-sensitive adhesive has a storage elastic modulus at a temperature of 80 ° C. of 0.1 MPa or more, preferably 0.15 MPa to 10 MPa. Further, the storage elastic modulus at a temperature of 23 ° C. of this highly elastic pressure-sensitive adhesive is preferably 0.1 MPa or more, more preferably 0.2 to 10 MPa.
  • the storage elastic modulus (dynamic elastic modulus) is a commonly used term of viscoelasticity, but gives a sample a strain or stress that changes (vibrates) with time, and Is a value obtained by a method of measuring the mechanical properties of a sample (dynamic viscoelasticity measurement) by measuring the stress or strain generated by the stress, and the strain is in phase with the stress and the phase is shifted by 90 degrees.
  • the elastic modulus is in phase with the vibrational stress.
  • the storage elastic modulus can be measured using a commercially available viscoelasticity measuring device, for example, a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by Reometric) as shown in the examples described later.
  • a dynamic viscoelasticity measuring device Dynamic Analyzer RDA II: manufactured by Reometric
  • various known temperature control devices such as a circulating thermostat, an electric heater, a Peltier element, and the like are used, and thereby the temperature at the time of measurement can be set.
  • the pressure-sensitive adhesive used in a normal image display device or an optical film therefor has a storage elastic modulus of at most about 0.1 MPa, and in comparison with that, a pressure-sensitive adhesive layer (second adhesive) defined in the present invention.
  • the storage elastic modulus of the layer is a high value as described above.
  • Such a high storage modulus that is, by using a hard pressure-sensitive adhesive, can compensate for a lack of cohesive force when placed in a high temperature environment or when a high temperature environment and a low temperature environment are repeated. It becomes possible to suppress the dimensional change accompanying the shrinkage
  • the high-elasticity adhesive used in the present invention can be composed of, for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether, or the like as a base polymer.
  • acrylic polymer like acrylic polymer, it has excellent optical transparency, retains appropriate wettability and cohesion, has excellent adhesion to substrates, and has weather resistance and heat resistance. It is preferable to select and use one that does not cause peeling problems such as floating and peeling under the conditions of heating and humidification.
  • the acrylic polymer is not particularly limited, but (meth) acrylic such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc.
  • An acid ester base polymer and a copolymer base polymer using two or more of these (meth) acrylic esters are preferably used.
  • polar monomers may be copolymerized with these base polymers.
  • polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Mention may be made of monomers having polar functional groups such as carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, such as acrylates and glycidyl (meth) acrylates.
  • acrylic polymers can be used alone as a pressure-sensitive adhesive, but a crosslinking agent is usually added to the pressure-sensitive adhesive.
  • a crosslinking agent a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group.
  • examples include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form a carbamide bond with a carboxyl group. Of these, polyisocyanate compounds are widely used as organic crosslinking agents.
  • the above-mentioned pressure-sensitive adhesive component may be an oligomer, specifically a urethane acrylate oligomer. Is preferably blended. Furthermore, it is preferable to use a pressure-sensitive adhesive containing such a urethane acrylate oligomer, which is cured by irradiating energy rays, so as to exhibit a high storage elastic modulus.
  • the high-elastic adhesive of the present invention includes, for example, Add appropriate additives such as natural and synthetic resins, tackifier resins, antioxidants, UV absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors, photoinitiators, etc. You can also. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.
  • a light diffusable adhesive containing a light diffusing agent can be used as the high-elasticity adhesive used in the present invention.
  • the light diffusing agent used here may be fine particles having a refractive index different from that of the base polymer constituting the pressure-sensitive adhesive layer (second adhesive layer), and may be fine particles made of an inorganic compound or fine particles made of an organic compound (polymer). Can be used.
  • Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45).
  • Examples of the fine particles made of an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index). 1.50 to 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46) ), Silicone resin beads (refractive index 1.46), and the like.
  • the base polymer constituting the pressure-sensitive adhesive layer (second adhesive layer) including the acrylic base polymer as described above often has a refractive index of around 1.4
  • the agent may be appropriately selected from those having a refractive index of about 1 to 2.
  • the difference in refractive index between the base polymer constituting the pressure-sensitive adhesive layer (second adhesive layer) and the light diffusing agent is usually 0.01 or more. It is preferable to set it to 01 or more and 0.5 or less.
  • the fine particles used as the light diffusing agent are preferably spherical and have a monodispersity.
  • fine particles having an average particle size in the range of about 2 to 6 ⁇ m are preferably used.
  • the blending amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the light diffusing pressure-sensitive adhesive layer in which it is blended, the brightness of the image display device to which it is applied, Generally, the amount is about 3 to 30 parts by weight with respect to 100 parts by weight of the base polymer constituting the pressure-sensitive adhesive layer.
  • the light diffusing pressure-sensitive adhesive layer containing the light diffusing agent ensures the brightness of the image display device to which the composite polarizing plate obtained using the light diffusing agent is applied, and hardly causes bleeding or blurring of the display image.
  • the haze is preferably in the range of 20 to 80%.
  • the haze is a value defined by JIS K 7105 and expressed as (diffuse transmittance / total light transmittance) ⁇ 100 (%).
  • the thickness of the light diffusable pressure-sensitive adhesive layer in which the light diffusing agent is blended is determined according to the adhesive force and the like, but is usually in the range of 1 to 40 ⁇ m.
  • the thickness of the light diffusive pressure-sensitive adhesive layer should be 3 to 25 ⁇ m to maintain good workability and high durability, and the brightness when the image display device is viewed from the front or obliquely. This is preferable from the viewpoint of keeping the display image from blurring and blurring.
  • water-based adhesive will be described.
  • the water-soluble crosslinkable epoxy resin can be obtained by reacting epichlorohydrin with a polyamide polyamine obtained by a reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid.
  • Examples of such commercially available polyamide epoxy resins include “Smiles Resin 650” and “Smiles Resin 675” sold by Sumika Chemtex Co., Ltd.
  • a water-soluble epoxy resin is used as the adhesive component, it is preferable to mix other water-soluble resin such as polyvinyl alcohol resin in order to further improve the coatability and adhesiveness.
  • Polyvinyl alcohol resin is modified such as partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol, etc. Polyvinyl alcohol resin may be used.
  • a saponified product of a copolymer of vinyl acetate and unsaturated carboxylic acid or a salt thereof, that is, carboxyl group-modified polyvinyl alcohol is preferably used.
  • carboxyl group-modified polyvinyl alcohol is preferably used.
  • the “carboxyl group” is a concept including —COOH and a salt thereof.
  • the epoxy resin and other water-soluble resin such as a polyvinyl alcohol resin added as necessary are dissolved in water to constitute an adhesive solution.
  • the water-soluble crosslinkable epoxy resin preferably has a concentration in the range of about 0.2 to 2 parts by weight per 100 parts by weight of water.
  • the amount is preferably about 1 to 10 parts by weight, more preferably about 1 to 5 parts by weight per 100 parts by weight of water.
  • suitable urethane resins include ionomer-type urethane resins, particularly polyester-based ionomer-type urethane resins.
  • the ionomer type is obtained by introducing a small amount of an ionic component (hydrophilic component) into the urethane resin constituting the skeleton.
  • the polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced.
  • Such an ionomer type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier and becomes an emulsion.
  • polyester ionomer-type urethane resins include “Hydran (registered trademark) AP-20” and “Hydran (registered trademark) APX-101H” sold by DIC Corporation. Available in form.
  • the isocyanate-based crosslinking agent is a compound having at least two isocyanato groups (—NCO) in the molecule.
  • Examples thereof include 2,4-tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,6 -In addition to polyisocyanate monomers such as hexamethylene diisocyanate and isophorone diisocyanate, adducts in which a plurality of these molecules are added to polyhydric alcohols such as trimethylolpropane, and three molecules of diisocyanate are isocyanates at each isocyanato group.
  • Examples include trifunctional isocyanurate having a nurate ring, and polyisocyanate-modified products such as a burette formed by hydration and decarboxylation of three diisocyanate molecules at each one-end isocyanato group.
  • Examples of commercially available isocyanate-based crosslinking agents that can be suitably used include “Hydran (registered trademark) Assistor C-1” sold by Dainippon Ink and Chemicals, Inc.
  • the concentration of the urethane resin is about 10 to 70% by weight, further 20% by weight or more, and 50% by weight or less from the viewpoint of viscosity and adhesiveness. Thus, those dispersed in water are preferred.
  • the blending amount may be appropriately selected so that the isocyanate crosslinking agent is about 5 to 100 parts by weight with respect to 100 parts by weight of the urethane resin.
  • the water-based adhesive as described above is applied to the adhesive surface of the polarizing film 10 or the transparent protective film 20 to form the first adhesive layer 41, and the two are bonded together.
  • the method for laminating the polarizing film and the transparent protective film is not particularly limited.
  • an adhesive is uniformly applied to the surface of the polarizing film or the transparent protective film, and the other film is overlapped on the coated surface and rolled.
  • the method of pasting and drying by etc. is mentioned. Drying is performed at a temperature of about 60 to 100 ° C., for example. After drying, it is preferable to cure at a temperature slightly higher than room temperature, for example, at a temperature of about 30 to 50 ° C. for about 1 to 10 days, in order to further increase the adhesive strength.
  • the solventless adhesive substantially does not contain a solvent, and generally includes a curable compound that is polymerized by heating or irradiation with active energy rays, and a polymerization initiator. From the viewpoint of reactivity, those that are cured by cationic polymerization are preferred, and epoxy adhesives are particularly preferred.
  • This adhesive is more preferably cured by cationic polymerization by heating or irradiation with active energy rays.
  • an epoxy compound that does not contain an aromatic ring in the molecule is suitably used as the curable compound.
  • An adhesive using an epoxy compound that does not contain an aromatic ring in the molecule is described in, for example, JP-A-2004-245925. Examples of such epoxy compounds that do not contain an aromatic ring include hydrides of aromatic epoxy compounds, alicyclic epoxy compounds, aliphatic epoxy compounds, and the like.
  • the curable epoxy compound used for the adhesive usually has two or more epoxy groups in the molecule.
  • Describing the hydride of an aromatic epoxy compound this can be obtained by selectively hydrogenating an aromatic epoxy compound to an aromatic ring under pressure in the presence of a catalyst.
  • the aromatic epoxy compound include bisphenol-type epoxy compounds such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether; phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde Examples thereof include novolak-type epoxy resins such as phenol novolac epoxy resins; polyfunctional epoxy compounds such as glycidyl ether of tetrahydroxydiphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinylphenol.
  • hydrogenated bisphenol A diglycidyl ether is preferred.
  • the polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof corresponds to this.
  • examples include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol
  • Each of the epoxy compounds exemplified here may be used alone or in combination with one or more other types.
  • a cationic polymerization initiator In order to cure the epoxy compound by cationic polymerization, a cationic polymerization initiator is blended.
  • the cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, or heating, and contributes to the initiation of the polymerization reaction of the epoxy group.
  • active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, or heating
  • a photocationic polymerization initiator When a photocationic polymerization initiator is used, curing at room temperature becomes possible, the need to consider the heat resistance of the polarizing film or distortion due to expansion is reduced, and the retardation film and the polarizing film can be favorably bonded. Moreover, since a photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy compound. Examples of compounds that generate cation species and Lewis acids upon irradiation with active energy rays include onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes. Among these, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.
  • photocationic polymerization initiators can be easily obtained as commercial products.
  • “Kayarad PCI-220”, “Kayarad PCI-620” manufactured by Nippon Kayaku Co., Ltd.
  • “UVI” -6990 manufactured by Union Carbide
  • Adekaoptomer SP-150 Adekaoptomer SP-170 "(above, manufactured by ADEKA Corporation)
  • CI-5102 "" CIT-1370 ",” “CIT-1682”, “CIP-1866S”, “CIP-2048S”, “CIP-2064S”
  • “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-101”, “ “TPS-102”, “TPS-103", “TPS-101”, “ “TPS-102”, “
  • the amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less with respect to 100 parts by weight of the epoxy compound.
  • a photosensitizer can be used together if necessary.
  • the reactivity is improved, and the mechanical strength and adhesive strength of the cured product can be improved.
  • the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes.
  • the amount is usually about 0.1 to 20 parts by weight with respect to 100 parts by weight of the photocationically polymerizable epoxy resin composition.
  • thermal cationic polymerization initiator will be described.
  • the compound that generates a cationic species or a Lewis acid by heating include benzylsulfonium salt, thiophenium salt, thiolanium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide.
  • thermal cationic polymerization initiators can also be easily obtained as commercial products.
  • ADKA OPTON CP77 and “ADEKA OPTON CP66” (above, manufactured by ADEKA Corporation), “CI- “2639” and “CI-2624” (Nippon Soda Co., Ltd.), “San-Aid SI-60L”, “Sun-Aid SI-80L” and “Sun-Aid SI-100L” (Sanshin Chemical Industry Co., Ltd.) ) And the like.
  • a composition for forming the second adhesive layer is dissolved or dispersed in an organic solvent such as toluene or ethyl acetate to prepare a solution having a concentration of 10 to 40% by weight.
  • an organic solvent such as toluene or ethyl acetate
  • the second adhesive layer is formed by directly applying to the surface of the retardation film and drying it.
  • the second adhesive layer formed in this way is bonded to a polarizing film and a retardation film by laminating a separator made of a resin film that has been treated with a silicone-based release agent. You can save it until you do.
  • transferring to a polarizing film or retardation film etc. are employable.
  • the polarizing film and the retardation film are bonded by a conventionally known technique.
  • the slow axis of the retardation film is orthogonal to the polarizing transmission axis of the polarizing film using a bonding roll or the like.
  • it is performed by the method of laminating
  • the composite polarizing plate of the present invention configured as described above can be bonded to a liquid crystal cell by further disposing a second adhesive on the outside of the retardation film. .
  • a composite polarizing plate is bonded to at least one side of the liquid crystal cell to constitute a liquid crystal display device.
  • the composite polarizing plate of the present invention can be disposed on both sides of the liquid crystal cell, the composite polarizing plate of the present invention can be disposed on one side, and another polarizing plate can be disposed on the other side.
  • the composite polarizing plate is usually arranged so that the retardation film side faces the liquid crystal cell when bonding to the liquid crystal cell.
  • FIG. 2 the example which arrange
  • FIG. 2A is a schematic cross-sectional view thereof, and FIG. 2B is a perspective view for explaining the relationship of shaft angles. Also in this example, each layer is shown in a separated state, but in actuality, adjacent layers are in close contact with each other.
  • a composite polarizing plate composed of a retardation film 30 / polarizing film 10 / transparent protective film 20 is laminated below the liquid crystal cell 60 so that the retardation film 30 side faces the liquid crystal cell 60.
  • the composite polarizing plate composed of the retardation film 30 / polarizing film 10 / transparent protective film 20 is also laminated on the upper side of the liquid crystal cell 60 so that the retardation film 30 side faces the liquid crystal cell 60.
  • the slow axis 35 of the retardation film 30 and the absorption axis 15 of the polarizing film 10 are in a parallel relationship
  • the lower polarizing film 10 has an absorption axis 15 that is the length of the liquid crystal cell 60.
  • the absorption axis 15 of the upper polarizing film 10 that is orthogonal to the side direction 65 is parallel to the long side direction 65 of the liquid crystal cell 60.
  • a backlight is disposed outside one of the transparent protective films 20 to form a liquid crystal display device. This configuration is particularly effective when the liquid crystal cell is in a transverse electric field mode.
  • Adhesive A1 Comprising Curable Epoxy Resin Composition Bis (3,4-epoxycyclohexyl) as an epoxycyclohexylmethyl ester of dicarboxylic acid corresponding to the above formula (III) which is an alicyclic epoxy resin 100 parts of methyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A as a hydrogenated epoxy resin, and 4,4′-bis (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate) as a photocationic polymerization initiator After 2.2 parts were mixed, defoaming was performed to obtain an adhesive A made of a curable epoxy resin composition. The photocationic polymerization initiator was blended as a 50% by mass propylene carbonate solution.
  • a 40 ⁇ m thick triacetylcellulose film having a saponified surface is bonded as an adhesive with a 5% by weight polyvinyl alcohol aqueous solution, dried to remove the solvent, and a single side protective film A polarizing film was attached.
  • Extrusion was performed to obtain a resin three-layer film having a core layer thickness of 60 ⁇ m and skin layers each having a thickness of 72 ⁇ m formed on both surfaces thereof.
  • This resin three-layer film was stretched twice at 142 ° C. to obtain a negative retardation film having a total thickness of 104 ⁇ m, an in-plane retardation of 140 nm, and an Nz coefficient of 0.0.
  • the thickness of each layer in the retardation film was about 30 ⁇ m for the core layer and about 37 ⁇ m for each skin layer.
  • the retardation film thus obtained was subjected to corona treatment at an irradiation dose of 16.8 kJ / m 2 .
  • seat which consists of adhesive A with the surface (polarizing film surface) opposite to the transparent protective film of the polarizing film by which the corona treatment surface and the transparent protective film bonded by the one side produced by said (a) were carried out.
  • the appearance of the composite polarizing plate thus obtained was good.
  • Example 3 (A) Production of polarizing film with single-sided transparent protective film 100 parts of bis (3,4-epoxycyclohexylmethyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A, and 4,4′-bis as a photocationic polymerization initiator After mixing 2.2 parts of (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate), defoaming was performed to obtain an adhesive A made of a curable epoxy resin composition. The cationic photopolymerization initiator was blended as a 50% propylene carbonate solution.
  • the retardation film surface of the composite polarizing plate obtained in Comparative Example 2 is fixed to soda glass (used as an alternative to a liquid crystal cell) with adhesive B, and subjected to autoclaving at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. It was made to adhere to a board. In this state, a heat shock test was performed by placing in an atmosphere of ⁇ 40 ° C. for 30 minutes, then moving to an atmosphere of + 80 ° C. and placing for 30 minutes as one cycle, and repeating this for 50 cycles. In the composite polarizing plate of Comparative Example 2, bubbles were generated in the pressure-sensitive adhesive layer between the retardation film and the glass after the test, which was not practical.
  • the retardation film surface of the composite polarizing plate obtained in Comparative Example 3 is fixed to soda glass (used as a substitute for a liquid crystal cell) with adhesive B, and subjected to an autoclave treatment at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. It was made to adhere to a board. In this state, a heat shock test was performed by placing in an atmosphere of ⁇ 40 ° C. for 30 minutes, then moving to an atmosphere of + 80 ° C. and placing for 30 minutes as one cycle, and repeating this for 50 cycles. In the composite polarizing plate of Comparative Example 3, bubbles were generated in the pressure-sensitive adhesive layer between the retardation film and the glass after the test, which was not practical.
  • the composite polarizing plate of the present invention can be widely used as an optical member in various liquid crystal display devices.
  • it can be used in large liquid crystal display devices such as televisions, computer displays, car navigation systems, mobile phones, and mobile terminal devices. It can be used as an optical member in the medium- and small-sized liquid crystal display device used.

Abstract

Disclosed is a composite polarizing plate wherein a transparent protective film (20) is bonded to one side of a polarizing film (10) through a first adhesive layer (41) and a retardation film (30) is bonded to the other side of the polarizing film (10) through a second adhesive layer (42). The retardation film (30) has a three-layer structure wherein a skin layer (32) composed of a (meth)acrylic resin composition containing rubber particles is formed on both sides of a core layer (31) composed of a styrene resin. The second adhesive layer (42) is composed of an epoxy resin composition containing an epoxy resin which is cured by irradiation of an active energy ray or heating, or is composed of a highly elastic adhesive having a storage modulus of not less than 0.1 MPa at a temperature of 80˚C.

Description

複合偏光板、複合偏光板の製造方法およびそれを用いた液晶表示装置Composite polarizing plate, method of manufacturing composite polarizing plate, and liquid crystal display device using the same
　本発明は、偏光フィルムの片面に透明保護フィルムが、他面には位相差フィルムがそれぞれ貼合された複合偏光板に関するものである。詳しくは、コア層をスキン層で挟んだ３層構造を有する位相差フィルムのスキン層に用いられる（メタ）アクリル系樹脂と偏光フィルムとの接着性に優れる複合偏光板およびそれを用いた液晶表示装置に関するものである。 The present invention relates to a composite polarizing plate in which a transparent protective film is bonded to one side of a polarizing film and a retardation film is bonded to the other side. Specifically, a composite polarizing plate excellent in adhesiveness between a (meth) acrylic resin and a polarizing film used for a skin layer of a retardation film having a three-layer structure in which a core layer is sandwiched between skin layers, and a liquid crystal display using the same It relates to the device.
　液晶表示装置は、消費電力が低く、低電圧で動作し、軽量で薄型であるなどの特徴を生かして、各種の表示用デバイスに用いられている。液晶表示装置は、液晶セル、偏光板、位相差フィルム、集光シート、拡散フィルム、導光板、光反射シートなど、多くの材料から構成されている。そのため、構成フィルムの枚数を減らしたり、フィルム又はシートの厚さを薄くしたりすることで、生産性や軽量化、明度の向上などを目指した改良が盛んに行われている。 Liquid crystal display devices are used in various display devices by taking advantage of features such as low power consumption, low voltage operation, light weight and thinness. The liquid crystal display device is composed of many materials such as a liquid crystal cell, a polarizing plate, a retardation film, a condensing sheet, a diffusion film, a light guide plate, and a light reflecting sheet. Therefore, improvements aimed at productivity, weight reduction, brightness improvement, and the like have been actively performed by reducing the number of constituent films or reducing the thickness of the film or sheet.
　さらに、液晶表示装置は厳しい耐久条件にも耐えうる製品が必要とされている。例えば、カーナビゲーションシステム用の液晶表示装置は、それが置かれる車内の温度や湿度が非常に高くなることがあり、また、携帯電話、携帯端末機器等のディスプレイやテレビ、コンピュータ用のディスプレイ等においても、それらの使用環境や設置場所によっては、温度および湿度の変化が激しい条件に曝される場合があるため、そのような厳しい条件の使用にも耐え得る製品性能が求められる。 Furthermore, liquid crystal display devices are required to be able to withstand severe durability conditions. For example, a liquid crystal display device for a car navigation system may have a very high temperature and humidity in a vehicle in which the liquid crystal display device is placed. Also, in a display for a mobile phone, a portable terminal device, etc., a television, a display for a computer, etc. However, depending on the usage environment and installation location, the temperature and humidity may be exposed to severe changes, so that product performance that can withstand use under such severe conditions is required.
　液晶表示装置の部品である偏光板は通常、偏光フィルムの両面または片面に透明な保護フィルムが積層された構造になっている。例えば、偏光フィルムは、ポリビニルアルコール系樹脂フィルムに一軸延伸と二色性色素による染色を行った後、ホウ酸処理して架橋反応を起こさせ、次いで水洗、乾燥する方法により製造されている。二色性色素としては、ヨウ素または二色性有機染料が用いられる。このようにして得られる偏光フィルムの両面または片面に保護フィルムを積層して偏光板とされ、液晶表示装置に組み込まれて使用される。保護フィルムには、トリアセチルロースに代表されるセルロースアセテート系樹脂フィルムが多く使用されており、その厚みは通例３０～１２０μｍ程度である。また、保護フィルムの積層には、ポリビニルアルコール系樹脂の水溶液からなる接着剤を用いることが多い。 A polarizing plate, which is a component of a liquid crystal display device, usually has a structure in which a transparent protective film is laminated on both sides or one side of a polarizing film. For example, a polarizing film is produced by a method in which a polyvinyl alcohol resin film is uniaxially stretched and dyed with a dichroic dye, then treated with boric acid to cause a crosslinking reaction, and then washed with water and dried. As the dichroic dye, iodine or a dichroic organic dye is used. A protective film is laminated on both sides or one side of the polarizing film thus obtained to form a polarizing plate, which is used by being incorporated in a liquid crystal display device. As the protective film, a cellulose acetate resin film typified by triacetylrose is often used, and its thickness is usually about 30 to 120 μm. In addition, an adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin is often used for laminating the protective film.
　二色性色素が吸着配向している偏光フィルムの両面または片面に、ポリビニルアルコール系樹脂の水溶液からなる接着剤を介してトリアセチルセルロースからなる保護フィルムを積層した偏光板は、湿熱条件下で長時間使用した場合に、偏光性能が低下したり、保護フィルムと偏光フィルムが剥離しやすかったりする問題がある。 A polarizing plate in which a protective film made of triacetyl cellulose is laminated on both sides or one side of a polarizing film on which a dichroic dye is adsorbed and oriented via an adhesive made of an aqueous solution of a polyvinyl alcohol resin is long under wet heat conditions. When used for a long time, there is a problem that the polarizing performance is lowered or the protective film and the polarizing film are easily peeled off.
　そこで、少なくとも一方の保護フィルムを、セルロースアセテート系以外の樹脂で構成する試みがある。例えば、特開平８－４３８１２号公報（特許文献１）には、偏光フィルムの両面に保護フィルムを積層した偏光板において、その保護フィルムの少なくとも一方を、位相差フィルムの機能を有する熱可塑性ノルボルネン系樹脂で構成することが記載されている。また、特開平９－３２５２１６号公報（特許文献２）には、偏光フィルムの保護層のうち少なくとも一方を複屈折性のフィルムで構成することが記載されている。 Therefore, there is an attempt to construct at least one protective film with a resin other than cellulose acetate. For example, in JP-A-8-43812 (Patent Document 1), in a polarizing plate in which protective films are laminated on both sides of a polarizing film, at least one of the protective films is a thermoplastic norbornene-based material having a retardation film function. It is described that it is made of resin. Japanese Patent Laid-Open No. 9-325216 (Patent Document 2) describes that at least one of the protective layers of the polarizing film is composed of a birefringent film.
　一方、スチレン系樹脂フィルムは、スチレン系樹脂の主鎖の分極率よりも側鎖の分極率が大きい（負に分極するということがある）ため、厚さ方向の屈折率が大きい負の位相差フィルムとして検討されている。ここで、厚さ方向の屈折率が大きい負の位相差フィルムとは、面内の最大屈折率方向（遅相軸方向）の屈折率をｎx、面内でそれと直交する方向（進相軸方向）の屈折率をｎy、厚さ方向の屈折率をｎzとしたとき、ｎz≒ｎx＞ｎyの関係を有し、(ｎx－ｎz)／(ｎx－ｎy)で定義されるＮｚ係数が概ね０（ゼロ）のフィルムである。しかし、スチレン系樹脂フィルムには、耐熱性、機械強度および耐薬品性に課題があり、実用化には至っていない。 On the other hand, a styrene resin film has a negative phase difference in which the refractive index in the thickness direction is large because the polarizability of the side chain is larger than the polarizability of the main chain of the styrene resin (it may be negatively polarized). It is being considered as a film. Here, the negative retardation film is larger refractive index in the thickness direction, the refractive indices n x a maximum refractive index direction in the plane (slow axis direction), a direction perpendicular thereto in the plane (fast axis when the refractive index in the direction) and n y, the refractive index in the thickness direction and n z, has a relationship of n z ≒ n x> n y , (n x -n z) / (n x -n y ) Is defined as a film having an Nz coefficient of approximately 0 (zero). However, styrene resin films have problems in heat resistance, mechanical strength, and chemical resistance, and have not yet been put into practical use.
　スチレン系樹脂の耐熱性については、ガラス転移温度（以下、Ｔｇと略すことがある）の高い樹脂を形成するモノマー、例えば、ノルボルネンや無水マレイン酸を共重合させることで、改善されることが知られているが、機械強度や耐薬品性は十分でない。 It is known that the heat resistance of a styrene resin can be improved by copolymerizing a monomer that forms a resin having a high glass transition temperature (hereinafter sometimes abbreviated as Tg), such as norbornene or maleic anhydride. However, mechanical strength and chemical resistance are not sufficient.
　スチレンに他のモノマーを共重合させたり、あるいはスチレン系フィルムに他の樹脂層を積層したりする技術も多数提案されている。例えば、特表２００２－５１７５８３号公報（特許文献３）には、スチレンを代表例とする芳香族ビニルモノマーとα－オレフィンとの本質的にランダムな共重合体をフィルムにすることが記載されており、そのフィルムと他のポリマー層との多層構造にすることも示唆されている。また、特開２００３－５０３１６号公報（特許文献４）や特開２００３－２０７６４０号公報（特許文献５）には、スチレンを代表例とする芳香族ビニルモノマーに非環状オレフィンモノマーおよび環状オレフィンモノマーを共重合させた三元共重合体を位相差フィルムにすることが記載されている。さらに、特開２００３－９０９１２号公報（特許文献６）には、ノルボルネン系樹脂からなる配向フィルムとスチレン－無水マレイン酸共重合樹脂からなる配向フィルムとを、接着層を介して積層し、位相差フィルムにすることが記載されており、特開２００４－１６７８２３号公報（特許文献７）には、ポリオレフィン系の多層フィルムにポリスチレン系のシートを積層することが記載されている。さらにまた、特開２００６－１９２６３７号公報（特許文献８）には、スチレン系樹脂からなる第１層と、ゴム粒子が配合されたアクリル系樹脂組成物からなる第２層とを、接着剤層を介さずに積層して位相差フィルムとすることが記載されている。
特開平８－４３８１２号公報 特開平９－３２５２１６号公報 特表２００２－５１７５８３号公報 特開２００３－５０３１６号公報 特開２００３－２０７６４０号公報 特開２００３－９０９１２号公報 特開２００４－１６７８２３号公報 特開２００６－１９２６３７号公報 Many techniques have been proposed in which other monomers are copolymerized with styrene, or other resin layers are laminated on a styrene film. For example, JP 2002-517583 A (Patent Document 3) describes that an essentially random copolymer of an aromatic vinyl monomer and an α-olefin, typically styrene, is used as a film. It has also been suggested to have a multilayer structure of the film and other polymer layers. In addition, JP-A-2003-50316 (Patent Document 4) and JP-A-2003-207640 (Patent Document 5) describe an aromatic vinyl monomer typified by styrene as an acyclic olefin monomer and a cyclic olefin monomer. It is described that a copolymerized terpolymer is used as a retardation film. Further, JP-A-2003-90912 (Patent Document 6) laminates an oriented film made of a norbornene-based resin and an oriented film made of a styrene-maleic anhydride copolymer resin through an adhesive layer, and has a retardation. JP-A-2004-167823 (Patent Document 7) describes that a polystyrene-based sheet is laminated on a polyolefin-based multilayer film. Furthermore, in JP-A-2006-192537 (Patent Document 8), an adhesive layer includes a first layer made of a styrene resin and a second layer made of an acrylic resin composition in which rubber particles are blended. It is described that the film is laminated without using a film to form a retardation film.
JP-A-8-43812 JP-A-9-325216 JP 2002-517583 A JP 2003-50316 A JP 2003-207640 A JP 2003-90912 A JP 2004-167823 A JP 2006-192637 A
　本発明者らは、前記特許文献８に開示されるような多層構造の位相差フィルム、特に、スチレン系樹脂からなるコア層の両面をアクリル系樹脂からなるスキン層で挟んだ構造の位相差フィルムを、偏光フィルムの片面に保護フィルムとしての機能を兼ねる層として配置した複合偏光板を開発すべく鋭意検討を行ってきた。その中で、従来の偏光板においてポリビニルアルコール系偏光フィルムとセルロースアセテート系保護フィルムとの接着に用いられている接着剤では、特に温度湿度の変化が激しい条件下で、偏光フィルムと前記のようなスキン層を有する位相差フィルムとが十分な強度で接着しないことが明らかになってきた。 The present inventors have disclosed a retardation film having a multilayer structure as disclosed in Patent Document 8, particularly a retardation film having a structure in which both surfaces of a core layer made of a styrene resin are sandwiched between skin layers made of an acrylic resin. Has been intensively studied to develop a composite polarizing plate in which a polarizing film is disposed as a layer also serving as a protective film on one side of the polarizing film. Among them, in an adhesive used for bonding a polyvinyl alcohol polarizing film and a cellulose acetate protective film in a conventional polarizing plate, the polarizing film and It has become clear that a retardation film having a skin layer does not adhere with sufficient strength.
　したがって本発明の目的は、偏光フィルムの一方の面に透明保護フィルムが積層され、他方の面には、特定の物性を示す第２の接着剤層を介して、スチレン系樹脂からなるコア層の両面に、ゴム粒子を含有する（メタ）アクリル系樹脂組成物からなるスキン層を有する３層構造の位相差フィルムが積層された、偏光フィルムと位相差フィルムとの間の接着力が高められた複合偏光板、または、温度湿度の変動に対する耐久性に優れた複合偏光板を提供することにある。 Accordingly, an object of the present invention is to provide a transparent protective film laminated on one surface of a polarizing film, and a core layer made of a styrene resin via a second adhesive layer showing specific physical properties on the other surface. The adhesive force between the polarizing film and the retardation film was enhanced, in which a retardation film having a three-layer structure having a skin layer made of a (meth) acrylic resin composition containing rubber particles was laminated on both sides. An object of the present invention is to provide a composite polarizing plate or a composite polarizing plate excellent in durability against fluctuations in temperature and humidity.
　すなわち、本発明は、偏光フィルムの一方の面に第１の接着剤層を介して透明保護フィルムが貼合され、偏光フィルムの他方の面に第２の接着剤層を介して位相差フィルムが貼合されてなる複合偏光板であって、該位相差フィルムがスチレン系樹脂からなるコア層の両面に、ゴム粒子を含有する（メタ）アクリル系樹脂組成物からなるスキン層が形成された３層構造からなり、前記第２の接着剤層が活性化エネルギー線の照射または加熱により硬化するエポキシ系樹脂を含有するエポキシ系樹脂組成物の硬化物層からなる複合偏光板である。 That is, in the present invention, a transparent protective film is bonded to one surface of a polarizing film via a first adhesive layer, and a retardation film is bonded to the other surface of the polarizing film via a second adhesive layer. A composite polarizing plate formed by bonding, wherein a skin layer made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer made of a styrene resin. It is a composite polarizing plate having a layer structure, wherein the second adhesive layer is composed of a cured product layer of an epoxy resin composition containing an epoxy resin that is cured by irradiation with activation energy rays or heating.
　前記活性化エネルギー線の照射または加熱により硬化するエポキシ系樹脂（硬化性エポキシ系樹脂）は、好ましくは、分子内に芳香環を含まないエポキシ系樹脂であり、さらに好ましくは、水素化エポキシ系樹脂、脂環式エポキシ系樹脂または脂肪族エポキシ系樹脂である。また、該エポキシ系樹脂を含有する硬化性エポキシ系樹脂組成物は、溶剤成分を実質的に含まない無溶剤型の組成物であることが好ましい。 The epoxy resin (curable epoxy resin) that is cured by irradiation or heating of the activation energy ray is preferably an epoxy resin that does not contain an aromatic ring in the molecule, and more preferably a hydrogenated epoxy resin. An alicyclic epoxy resin or an aliphatic epoxy resin. Moreover, it is preferable that the curable epoxy resin composition containing the epoxy resin is a solventless composition that does not substantially contain a solvent component.
　本発明において、位相差フィルムのコア層の膜厚は１０～１００μｍであるのが好ましく、スキン層の膜厚は、１０～１００μｍであることが好ましい。 In the present invention, the thickness of the core layer of the retardation film is preferably 10 to 100 μm, and the thickness of the skin layer is preferably 10 to 100 μm.
　また、位相差フィルムにおいては、コア層はガラス転位温度が１２０℃以上であるスチレン系樹脂から構成されることが好ましく、また、スキン層はガラス転位温度が１２０℃以下である（メタ）アクリル系樹脂から構成されることが好ましい。 In the retardation film, the core layer is preferably composed of a styrene resin having a glass transition temperature of 120 ° C. or higher, and the skin layer is a (meth) acrylic resin having a glass transition temperature of 120 ° C. or lower. It is preferable to be comprised from resin.
　さらに、本発明によれば、液晶セルの少なくとも一方の面に、前記したいずれかの複合偏光板が配置された液晶表示装置も提供される。ここで複合偏光板は、その位相差フィルム側が液晶セルに面するように配置される。 Furthermore, according to the present invention, there is also provided a liquid crystal display device in which any one of the above-described composite polarizing plates is disposed on at least one surface of the liquid crystal cell. Here, the composite polarizing plate is disposed so that the retardation film side faces the liquid crystal cell.
　さらに、本発明は、偏光フィルムの一方の面に第１の接着剤層を介して透明保護フィルムが貼合され、偏光フィルムの他方の面に第２の接着剤層を介して位相差フィルムが貼合されてなる複合偏光板であって、位相差フィルムがスチレン系樹脂からなるコア層の両面に、ゴム粒子を含有する（メタ）アクリル系樹脂組成物からなるスキン層が形成された３層構造からなり、第２の接着剤層が８０℃の温度において０．１ＭＰａ以上の貯蔵弾性率を示す高弾性粘着剤から形成されていることを特徴とする複合偏光板にも関する。 Further, in the present invention, a transparent protective film is bonded to one surface of a polarizing film via a first adhesive layer, and a retardation film is bonded to the other surface of the polarizing film via a second adhesive layer. 3 layers in which a composite polarizing plate is bonded, and a skin layer made of a (meth) acrylic resin composition containing rubber particles is formed on both sides of a core layer made of a styrene resin. The present invention also relates to a composite polarizing plate characterized in that the second adhesive layer is formed of a highly elastic pressure-sensitive adhesive exhibiting a storage elastic modulus of 0.1 MPa or more at a temperature of 80 ° C.
　本発明において、偏光フィルムと位相差フィルムの貼合に用いる粘着剤は、８０℃の温度における貯蔵弾性率が０．１ＭＰａ以上であり、好ましくは０．１５ＭＰａ～１０ＭＰａである。このように高い温度でも一定以上の貯蔵弾性率を示す高弾性粘着剤を用いることにより、偏光フィルムと、ゴム粒子を含有する（メタ）アクリル系樹脂組成物スキン層との密着が極めて良好に向上し、温度湿度の変動に対する耐久性に優れた複合偏光板が得られる。また、前記高弾性粘着剤の２３℃の温度における貯蔵弾性率は０．１ＭＰａ以上であることが好ましく、さらに好ましくは０．２～１０ＭＰａである。 In the present invention, the adhesive used for laminating the polarizing film and the retardation film has a storage elastic modulus at a temperature of 80 ° C. of 0.1 MPa or more, preferably 0.15 MPa to 10 MPa. By using a highly elastic pressure-sensitive adhesive exhibiting a storage elastic modulus of a certain level or higher even at such a high temperature, the adhesion between the polarizing film and the (meth) acrylic resin composition skin layer containing rubber particles is extremely improved. Thus, a composite polarizing plate having excellent durability against temperature and humidity fluctuations can be obtained. Further, the storage elastic modulus at a temperature of 23 ° C. of the highly elastic pressure-sensitive adhesive is preferably 0.1 MPa or more, and more preferably 0.2 to 10 MPa.
　本発明において、位相差フィルムのコア層の膜厚は１０～１００μｍであることが好ましく、スキン層の膜厚は１０～１００μｍであることが好ましい。 In the present invention, the thickness of the core layer of the retardation film is preferably 10 to 100 μm, and the thickness of the skin layer is preferably 10 to 100 μm.
　また、位相差フィルムのコア層を構成するスチレン系樹脂のガラス転移温度は１２０℃以上であることが好ましく、スキン層を構成する（メタ）アクリル系系樹脂組成物のガラス転移温度が１２０℃以下であることが好ましい。 Moreover, it is preferable that the glass transition temperature of the styrene resin which comprises the core layer of retardation film is 120 degreeC or more, and the glass transition temperature of the (meth) acrylic-type resin composition which comprises a skin layer is 120 degrees C or less. It is preferable that
　また、第２の接着剤層の厚みは１～４０μｍであることが好ましい。
　本発明によれば、液晶セルの少なくとも一方の面に、前記の複合偏光板が配置されている液晶表示装置が提供される。ここで複合偏光板は、その位相差フィルム側が液晶セルに面するように配置される。 The thickness of the second adhesive layer is preferably 1 to 40 μm.
According to the present invention, there is provided a liquid crystal display device in which the composite polarizing plate is disposed on at least one surface of a liquid crystal cell. Here, the composite polarizing plate is disposed so that the retardation film side faces the liquid crystal cell.
　さらに、本発明によれば、前記の複合偏光板の製造方法が提供される。 Furthermore, according to this invention, the manufacturing method of the said composite polarizing plate is provided.
　本発明の複合偏光板は、スチレン系樹脂からなるコア層の両面にゴム粒子が配合された（メタ）アクリル系樹脂組成物からなるスキン層が形成された３層構造の位相差フィルムが、偏光フィルムの片面に積層され、かつ偏光フィルムと前記位相差フィルムのスキン層とが十分な接着強度で接合したものである。また、外観不良などの問題を起こすこともない。この複合偏光板を用いた液晶表示装置も、偏光フィルムと位相差フィルムが十分な強度で接着しているので、耐久性に優れたものである。 The composite polarizing plate of the present invention has a three-layer retardation film in which a skin layer made of a (meth) acrylic resin composition in which rubber particles are blended on both sides of a core layer made of a styrene resin, The film is laminated on one side of the film and the polarizing film and the skin layer of the retardation film are joined with sufficient adhesive strength. In addition, problems such as poor appearance are not caused. The liquid crystal display device using this composite polarizing plate is also excellent in durability because the polarizing film and the retardation film are bonded with sufficient strength.
　また、本発明における硬化性エポキシ系樹脂組成物として、溶剤成分を実質的に含まない無溶剤型の組成物を用いた場合には、無溶剤型であることにより乾燥・養生の工程が短縮できるため、製造工程が短縮され複合偏光板の生産性を向上させることができる。 In addition, when a solvent-free composition substantially free of solvent components is used as the curable epoxy resin composition in the present invention, the drying and curing process can be shortened by the solvent-free composition. Therefore, the manufacturing process can be shortened and the productivity of the composite polarizing plate can be improved.
　さらに、本発明の複合偏光板は、スチレン系樹脂からなるコア層の両面にゴム粒子が配合された（メタ）アクリル系樹脂組成物からなるスキン層が形成された３層構造の位相差フィルムが、偏光フィルムの片面に、高い貯蔵弾性率を有する粘着剤層（第２の接着剤層）を介して貼合されている場合、偏光フィルムと前記位相差フィルムのスキン層とが十分な接着強度で接合したものとなる。したがって、温度や湿度の変化が大きい環境下においても、偏光フィルムと位相差フィルムの剥れが生じ難く、また、外観不良などの問題を起こすことのない耐久性に優れた複合偏光板を提供することができる。さらに、この複合偏光板を用いた液晶表示装置も、偏光フィルムと位相差フィルムが十分な強度で接着しているので、耐久性に優れたものとなる。 Furthermore, the composite polarizing plate of the present invention is a three-layer retardation film in which a skin layer made of a (meth) acrylic resin composition in which rubber particles are blended is formed on both surfaces of a core layer made of a styrene resin. When the polarizing film is bonded to one surface of the polarizing film via a pressure-sensitive adhesive layer (second adhesive layer) having a high storage elastic modulus, the polarizing film and the skin layer of the retardation film have sufficient adhesive strength. Will be joined. Accordingly, it is possible to provide a composite polarizing plate having excellent durability that does not easily cause peeling of the polarizing film and the retardation film even under an environment in which changes in temperature and humidity are large and does not cause problems such as poor appearance. be able to. Furthermore, the liquid crystal display device using this composite polarizing plate also has excellent durability because the polarizing film and the retardation film are bonded with sufficient strength.
本発明に係る複合偏光板の層構成の例を示す断面模式図である。It is a cross-sectional schematic diagram which shows the example of the layer structure of the composite polarizing plate which concerns on this invention. （Ａ）は本発明の複合偏光板を液晶表示装置に適用した例を示す断面模式図であり、（Ｂ）はそのときの軸角度の関係を説明するための斜視図である。(A) is a cross-sectional schematic diagram which shows the example which applied the composite polarizing plate of this invention to the liquid crystal display device, (B) is a perspective view for demonstrating the relationship of the axial angle at that time.
符号の説明Explanation of symbols
　１０　偏光フィルム、１５　偏光フィルムの吸収軸、２０　透明保護フィルム、３０　位相差フィルム、３１　コア層、３２　スキン層、３５　位相差フィルムの遅相軸、４１　第１の接着剤層、４２　第２の接着剤層、５０　第２の粘着剤層、５５　セパレータ、６０　液晶セル、６５　液晶セルの長辺方向。 10 polarizing film, 15 polarizing film absorption axis, 20 transparent protective film, 30 retardation film, 31 core layer, 32 skin layer, 35 retardation film slow axis, 41 first adhesive layer, 42 second Long side direction of adhesive layer, 50 second adhesive layer, 55 separator, 60 liquid crystal cell, 65 liquid crystal cell.
　以下、適宜添付の図面も参照しながら、本発明を詳細に説明する。
　図１は、本発明に係る複合偏光板の層構成の例を示す断面模式図である。本発明の複合偏光板は、図１に示すように、偏光フィルム１０の一方の面に、第１の接着剤層４１を介して透明保護フィルム２０が積層され、偏光フィルム１０の他方の面には、第２の接着剤層４２を介して位相差フィルム３０が積層されたものである。位相差フィルム３０は、スチレン系樹脂からなるコア層３１の両面に、ゴム粒子を含有する（メタ）アクリル系樹脂組成物からなるスキン層３２が形成された３層構造を有する。位相差フィルム３０の偏光フィルム１０に貼り合わされた面と反対側の面には、液晶セルなどの他部材に貼り合わせるための第２の粘着剤層５０が設けられることが多く、その場合は他部材への貼合まで第２の粘着剤層５０の表面を仮着保護するセパレータ５５を設けるのが通例である。なお図１では、わかりやすくするために一部の層を離間して示しているが、実際には隣り合う各層が密着貼合されていることになる。 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as appropriate.
FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of a composite polarizing plate according to the present invention. In the composite polarizing plate of the present invention, as shown in FIG. 1, the transparent protective film 20 is laminated on one surface of the polarizing film 10 via the first adhesive layer 41, and on the other surface of the polarizing film 10. Is obtained by laminating the retardation film 30 via the second adhesive layer 42. The retardation film 30 has a three-layer structure in which a skin layer 32 made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer 31 made of a styrene resin. A second pressure-sensitive adhesive layer 50 for bonding to other members such as a liquid crystal cell is often provided on the surface opposite to the surface bonded to the polarizing film 10 of the retardation film 30, and in that case It is usual to provide a separator 55 that temporarily protects the surface of the second pressure-sensitive adhesive layer 50 until bonding to a member. Note that in FIG. 1, some layers are shown separated for the sake of clarity, but in actuality, adjacent layers are closely bonded.
　［偏光フィルム］
　偏光フィルム１０は、自然光からある一方向の直線偏光を選択的に透過する機能を有するものである。例えば、ポリビニルアルコール系フィルムにヨウ素を吸着・配向させたヨウ素系偏光フィルム、ポリビニルアルコール系フィルムに二色性の染料を吸着・配向させた染料系偏光フィルム、およびリオトロピック液晶状態の二色性染料をコーティングし、配向・固定化した塗布型偏光フィルムなどが挙げられる。これらのヨウ素系偏光フィルム、染料系偏光フィルム、および塗布型偏光フィルムは、自然光からある一方向の直線偏光を選択的に透過し、もう一方向の直線偏光を吸収する機能を有するもので、吸収型偏光フィルムと呼ばれている。本発明に用いる偏光フィルムは、前述した吸収型偏光フィルムだけでなく、自然光からある一方向の直線偏光を選択的に透過し、もう一方向の直線偏光を反射又は散乱する機能を有する反射型偏光フィルム、および散乱型偏光フィルムと呼ばれているものでも構わない。また、ここで具体的に挙げた偏光フィルムは、必ずしもこれらに限定されるわけではなく、自然光からある一方向の直線偏光を選択的に透過する機能を有するものであればよい。これらの偏光フィルムの中でも、視認性に優れている吸収型偏光フィルムが好ましく、その中でも、偏光度及び透過率に優れるヨウ素系偏光フィルムを偏光フィルムが、最も好ましい。 [Polarized film]
The polarizing film 10 has a function of selectively transmitting linearly polarized light in one direction from natural light. For example, an iodine polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol film, a dye polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol film, and a dichroic dye in a lyotropic liquid crystal state Examples thereof include a coated polarizing film that is coated, oriented and fixed. These iodine-based polarizing films, dye-based polarizing films, and coating-type polarizing films have a function of selectively transmitting one direction of linearly polarized light from natural light and absorbing the other direction of linearly polarized light. It is called a type polarizing film. The polarizing film used in the present invention is not only the absorption polarizing film described above, but also a reflective polarizing film having a function of selectively transmitting one direction of linearly polarized light from natural light and reflecting or scattering the other direction of linearly polarized light. What is called a film and a scattering type polarizing film may be used. Moreover, the polarizing film specifically mentioned here is not necessarily limited to these, What is necessary is just to have a function which selectively permeate | transmits the linearly polarized light of a certain one direction from natural light. Among these polarizing films, an absorbing polarizing film excellent in visibility is preferable, and among them, a polarizing film is most preferable an iodine polarizing film excellent in polarization degree and transmittance.
　例えば、ポリビニルアルコール系樹脂を用いた偏光フィルムは、ポリビニルアルコール系樹脂フィルムに二色性色素を吸着配向させて、所定の偏光特性が得られるようにしたものである。二色性色素としては、ヨウ素や二色性有機染料が用いられる。そこで偏光フィルム１０として具体的には、ポリビニルアルコール系樹脂フィルムにヨウ素が吸着配向しているヨウ素系偏光フィルムや、ポリビニルアルコール系樹脂フィルムに二色性有機染料が吸着配向している染料系偏光フィルムを挙げることができる。 For example, a polarizing film using a polyvinyl alcohol-based resin is obtained by adsorbing and orienting a dichroic dye on a polyvinyl alcohol-based resin film so as to obtain predetermined polarizing characteristics. As the dichroic dye, iodine or a dichroic organic dye is used. Therefore, specifically as the polarizing film 10, an iodine polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol resin film, and a dye polarizing film in which a dichroic organic dye is adsorbed and oriented on a polyvinyl alcohol resin film. Can be mentioned.
　前記のポリビニルアルコール系樹脂を用いた偏光フィルムに用いるポリビニルアルコール系樹脂は、ポリ酢酸ビニル系樹脂をケン化することにより得られる。ポリ酢酸ビニル系樹脂としては、酢酸ビニルの単独重合体であるポリ酢酸ビニルのほか、酢酸ビニルと、これと共重合可能な他の単量体との共重合体などが例示される。酢酸ビニルと共重合可能な他の単量体としては、たとえば、不飽和カルボン酸類、不飽和スルホン酸類、オレフィン類、ビニルエーテル類などが挙げられる。ポリビニルアルコール系樹脂のケン化度は、通常８５～１００モル％程度、好ましくは９８～１００モル％である。ポリビニルアルコール系樹脂はさらに変性されていてもよく、たとえば、アルデヒド類で変性されたポリビニルホルマールやポリビニルアセタール、ポリビニルブチラールなども使用し得る。ポリビニルアルコール系樹脂の重合度は、通常１,０００～１０,０００程度、好ましくは１,５００～１０,０００程度である。 The polyvinyl alcohol resin used in the polarizing film using the polyvinyl alcohol resin is obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and the like. The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal modified with aldehydes, polyvinyl acetal, polyvinyl butyral, and the like may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 10,000.
　前記のポリビニルアルコール系樹脂を製膜したものが、偏光フィルムの原反フィルムとして用いられる。ポリビニルアルコール系樹脂を製膜する方法は特に限定されるものでなく、公知の方法で製膜することができる。ポリビニルアルコール系原反フィルムの厚みは特に限定されないが、たとえば、２μｍ～１５０μｍ程度である。 A film obtained by forming the polyvinyl alcohol resin is used as an original film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but is, for example, about 2 μm to 150 μm.
　前記の偏光フィルムは、通常、前記したようなポリビニルアルコール系樹脂からなる原反フィルムの水分を調整する調湿工程、ポリビニルアルコール系樹脂フィルムを一軸延伸する工程、ポリビニルアルコール系樹脂フィルムを二色性色素で染色してその二色性色素を吸着させる工程、二色性色素が吸着配向されたポリビニルアルコール系樹脂フィルムをホウ酸水溶液で処理する工程、および、ホウ酸水溶液による処理後に水洗する工程を経て製造される。 The polarizing film is usually a humidity adjusting step for adjusting the moisture of the raw film made of the polyvinyl alcohol resin as described above, a step of uniaxially stretching the polyvinyl alcohol resin film, and a dichroic polyvinyl alcohol resin film. A step of dyeing with a dye and adsorbing the dichroic dye, a step of treating the polyvinyl alcohol resin film on which the dichroic dye is adsorbed and oriented with an aqueous boric acid solution, and a step of washing with water after the treatment with the boric acid aqueous solution It is manufactured after.
　一軸延伸は、二色性色素による染色の前に行なってもよいし、染色と同時に行なってもよいし、染色の後に行なってもよい。一軸延伸を二色性色素による染色の後で行なう場合には、この一軸延伸は、ホウ酸処理の前に行なってもよいし、ホウ酸処理中に行なってもよい。また、これらの複数の段階で一軸延伸を行なうことも可能である。一軸延伸にあたっては、周速の異なるロール間で一軸に延伸してもよいし、熱ロールを用いて一軸に延伸してもよい。また、大気中で延伸を行なうなどの乾式延伸であってもよいし、溶剤にて膨潤させた状態で延伸を行なう湿式延伸であってもよい。延伸倍率は、通常４～８倍程度である。上記水洗後、乾燥して得られる偏光フィルムの厚みは、たとえば、１～５０μｍ程度とすることができる。 The uniaxial stretching may be performed before the dyeing with the dichroic dye, may be performed simultaneously with the dyeing, or may be performed after the dyeing. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, it is also possible to perform uniaxial stretching in these several steps. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, it may be dry stretching such as stretching in the air, or may be wet stretching in which stretching is performed in a state swollen with a solvent. The draw ratio is usually about 4 to 8 times. The thickness of the polarizing film obtained by drying after washing with water can be, for example, about 1 to 50 μm.
　［位相差フィルム］
　偏光フィルム１０のもう一方の面に積層される位相差フィルム３０は、そのコア層３１がスチレン系樹脂からなり、その両面に、ゴム粒子を含有する（メタ）アクリル系樹脂組成物からなるスキン層３２が形成されたものである。 [Phase difference film]
The phase difference film 30 laminated on the other surface of the polarizing film 10 has a core layer 31 made of a styrene resin, and a skin layer made of a (meth) acrylic resin composition containing rubber particles on both surfaces. 32 is formed.
　コア層３１を構成するスチレン系樹脂は、スチレン又はその誘導体の単独重合体であることができるほか、スチレン若しくはその誘導体と他の共重合性モノマーとの、二元又はそれ以上の共重合体であることもできる。ここで、スチレン誘導体とは、スチレンに他の基が結合した化合物であって、例えば、ｏ－メチルスチレン、ｍ－メチルスチレン、ｐ－メチルスチレン、２，４－ジメチルスチレン、ｏ－エチルスチレン、ｐ－エチルスチレンのようなアルキルスチレンや、ヒドロキシスチレン、tert－ブトキシスチレン、ビニル安息香酸、ｏ－クロロスチレン、ｐ－クロロスチレン等の、スチレンのベンゼン核に水酸基、アルコキシ基、カルボキシル基、ハロゲンなどが導入された置換スチレンなどが挙げられる。前記特許文献４や特許文献５に開示されるような三元共重合体も、用いることができる。スチレン系樹脂は、スチレン又はスチレン誘導体と、アクリロニトリル、無水マレイン酸、メチルメタクリレートおよびブタジエンから選ばれる少なくとも１種のモノマーとの共重合体であることが好ましい。コア層は耐熱性のスチレン系樹脂で構成されるのが好ましく、一般にそのＴｇは１００℃以上である。スチレン系樹脂のより好ましいＴｇは、１２０℃以上である。 The styrenic resin constituting the core layer 31 may be a homopolymer of styrene or a derivative thereof, or may 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 other groups are 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, etc., styrene benzene nucleus with hydroxyl group, alkoxy group, carboxyl group, halogen, etc. Substituted styrene in which is introduced. A terpolymer as disclosed in Patent Document 4 and Patent Document 5 can also be used. The styrenic 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 core layer is preferably composed of a heat-resistant styrene resin, and generally has a Tg of 100 ° C. or higher. A more preferable Tg of the styrene resin is 120 ° C. or more.
　スチレン系樹脂からなるコア層３１は、その厚みが１０～１００μｍとなるように設定することが望ましい。その厚みが１０μｍ未満では、延伸によって十分なレターデーション値が発現しにくいことがある。一方、その厚みが１００μｍを越えると、フィルムの衝撃強度が弱くなりやすいとともに、外部応力によるレターデーション変化が大きくなる傾向にあり、液晶表示装置に適用したときに白抜けなどが発生しやすくなり、表示性能が低下しやすい。 The core layer 31 made of styrene-based resin is desirably set so that its thickness is 10 to 100 μm. If the thickness is less than 10 μm, a sufficient retardation value may not easily be exhibited by stretching. On the other hand, 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. Display performance is likely to deteriorate.
　前記のスチレン系樹脂からなるコア層３１の両面に配置されるスキン層３２は、（メタ）アクリル系樹脂にゴム粒子が配合されている（メタ）アクリル系樹脂組成物からなる。ここで（メタ）アクリル系樹脂としては、例えば、メタクリル酸アルキルエステル又はアクリル酸アルキルエステルの単独重合体や、メタクリル酸アルキルエステルとアクリル酸アルキルエステルとの共重合体などが挙げられる。メタクリル酸アルキルエステルとして具体的には、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピルなどが、またアクリル酸アルキルエステルとして具体的には、アクリル酸メチル、アクリル酸エチル、アクリル酸プロピルなどが挙げられる。このような（メタ）アクリル系樹脂には、汎用の（メタ）アクリル系樹脂として市販されているものが使用できる。なお、（メタ）アクリル系樹脂の中には、耐衝撃（メタ）アクリル系樹脂と呼ばれるもの、また、グルタル酸無水物構造やラクトン環構造を主鎖中に有する高耐熱（メタ）アクリル系樹脂と呼ばれるものも含まれる。 The skin layer 32 disposed on both surfaces of the core layer 31 made of the styrene resin 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 a methacrylic acid alkyl ester or a homopolymer of an acrylic acid alkyl ester, and a copolymer of a methacrylic acid alkyl ester and an acrylic acid alkyl ester. 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.
　（メタ）アクリル系樹脂に配合されるゴム粒子は、アクリル系ゴム粒子が好ましい。アクリル系ゴム粒子とは、アクリル酸ブチルやアクリル酸２－エチルヘキシル等のアクリル酸アルキルエステルを主成分とし、多官能モノマーの存在下に重合させて得られるゴム弾性を有する粒子である。このようなゴム弾性を有する粒子が単層で形成されたものでもよいし、ゴム弾性層を少なくとも１層有する多層構造粒子であってもよい。多層構造のアクリル系ゴム粒子としては、前記のようなゴム弾性を有する粒子を核とし、その周りを硬質のメタクリル酸アルキルエステル系重合体で覆ったもの、硬質のメタクリル酸アルキルエステル系重合体を核とし、その周りを前記のようなゴム弾性を有するアクリル系重合体で覆ったもの、また硬質の核の周りを、ゴム弾性を有するアクリル系重合体で覆い、さらにその周りを硬質のメタクリル酸アルキルエステル系重合体で覆ったものなどが挙げられる。これらのゴム粒子平均直径は、粒子中に形成される弾性層の直径または外径でこれを表すと通常５０～４００ｎｍ程度の範囲にある。 The rubber particles blended in the (meth) acrylic resin are preferably acrylic rubber particles. Acrylic rubber particles are particles having rubber elasticity obtained by polymerizing in the presence of a polyfunctional monomer containing an alkyl acrylate ester such as butyl acrylate or 2-ethylhexyl acrylate as a main component. Such particles having rubber elasticity may be formed as a single layer, or may be multilayer structure particles having at least one rubber elastic layer. As the acrylic rubber particles having a multilayer structure, the 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 periphery thereof is hard methacrylic acid. Examples thereof include those covered with an alkyl ester polymer. The average diameter of these rubber particles is usually in the range of about 50 to 400 nm in terms of the diameter or outer diameter of the elastic layer formed in the particles.
　スキン層３２を構成する（メタ）アクリル系樹脂組成物における前記ゴム粒子の含有量は、（メタ）アクリル系樹脂１００重量部あたり、通常５～５０重量部程度である。（メタ）アクリル系樹脂およびアクリル系ゴム粒子は、それらを混合した状態で市販されているので、その市販品を用いることができる。アクリル系ゴム粒子が配合された（メタ）アクリル系樹脂の市販品の例として、住友化学株式会社から販売されている“HT55X”や“テクノロイ（登録商標）S001”などが挙げられる。このような（メタ）アクリル系樹脂組成物は、一般に１６０℃以下のＴｇを有するが、その好ましいＴｇは１２０℃以下、さらには１１０℃以下である。 The content of the rubber particles in the (meth) acrylic resin composition constituting the skin layer 32 is usually about 5 to 50 parts by weight per 100 parts by weight of the (meth) acrylic resin. Since (meth) acrylic resin and acrylic rubber particles are commercially available in a state where they are mixed, commercially available products thereof can be used. Examples of commercially available (meth) acrylic resins containing acrylic rubber particles include “HT55X” and “Technoloy (registered trademark) S001” sold by Sumitomo Chemical Co., Ltd. Such a (meth) acrylic resin composition generally has a Tg of 160 ° C. or lower, but a preferable Tg is 120 ° C. or lower, and further 110 ° C. or lower.
　ゴム粒子、好ましくはアクリル系ゴム粒子、が配合された（メタ）アクリル系樹脂組成物からなるスキン層３２の厚みは好ましくは１０～１００μｍである。その厚みが１０μｍ未満の場合、製膜が難しくなる傾向にある。一方、厚みが１００μｍを越えると、この（メタ）アクリル系樹脂層のレターデーションが無視できなくなる傾向にある。 The thickness of the skin layer 32 made of a (meth) acrylic resin composition containing rubber particles, preferably acrylic rubber particles, is preferably 10 to 100 μm. When the thickness is less than 10 μm, film formation tends to be difficult. On the other hand, when the thickness exceeds 100 μm, the retardation of the (meth) acrylic resin layer tends to be ignorable.
　前記のとおり、本発明で使用する位相差フィルム３０において、スチレン系樹脂からなるコア層３１は、そのＴｇが１２０℃以上であるのが好ましく、一方、ゴム粒子が配合された（メタ）アクリル系樹脂組成物からなるスキン層３２は、そのＴｇが１２０℃以下、さらには１１０℃以下であるのが好ましい。両者のＴｇが重ならず、スチレン系樹脂からなるコア層３１のほうが、ゴム粒子が配合された（メタ）アクリル系樹脂組成物からなるスキン層３２よりも高いＴｇを有するようにするのが好ましい。 As described above, in the phase difference film 30 used in the present invention, the core layer 31 made of a styrene resin preferably has a Tg of 120 ° C. or higher, while the (meth) acrylic compound in which rubber particles are blended. The skin layer 32 made of the resin composition preferably has a Tg of 120 ° C. or lower, more preferably 110 ° C. or lower. It is preferable that the core layers 31 made of a styrene resin have a higher Tg than the skin layer 32 made of a (meth) acrylic resin composition containing rubber particles. .
　本発明に使用される位相差フィルム３０を製造するには、例えば、スチレン系樹脂と、ゴム粒子が配合された（メタ）アクリル系樹脂組成物とを共押出し、その後延伸すればよい。その他、それぞれ単層のフィルムを作製した後で、ヒートラミネーションにより熱融着させ、それを延伸する方法も可能である。 In order to produce the retardation film 30 used in the present invention, for example, a styrene resin and a (meth) acrylic resin composition containing rubber particles may be coextruded and then stretched. In addition, after each single-layer film is produced, heat fusion can be performed by heat lamination and the film can be stretched.
　この位相差フィルム３０においては、スチレン系樹脂からなるコア層３１の両面に、ゴム粒子が配合された（メタ）アクリル系樹脂組成物からなるスキン層３２が形成された３層構造とされる。この３層構造において、両面に配置されるスキン層３２は通常、ほぼ同じ厚みとされる。このように３層構造とすることにより、ゴム粒子が配合された（メタ）アクリル系樹脂組成物からなるスキン層３２が保護層として働き、機械強度や耐薬品性に優れたものとなる。 The retardation film 30 has a three-layer structure in which a skin layer 32 made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer 31 made of a styrene resin. In this three-layer structure, the skin layers 32 disposed on both sides are usually substantially the same thickness. Thus, by setting it as a 3 layer structure, the skin layer 32 which consists of a (meth) acrylic-type resin composition with which the rubber particle was mix | blended works as a protective layer, and becomes excellent in mechanical strength and chemical resistance.
　以上のように構成される位相差フィルム３０は、延伸により面内レターデーションが付与される。延伸は、公知の縦一軸延伸やテンター横一軸延伸、同時二軸延伸、逐次二軸延伸などで行うことができ、所望とするレターデーション値が得られるように延伸すればよい。 The retardation film 30 configured as described above is given in-plane retardation by stretching. Stretching can be performed by well-known longitudinal uniaxial stretching, tenter lateral uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, etc., and may be performed so as to obtain a desired retardation value.
　［透明保護フィルム］
　偏光フィルム１０の一方の面に積層される透明保護フィルム２０は、透明性、機械的強度、熱安定性、水分遮蔽性、位相差値の安定性などに優れるものが好ましい。透明保護フィルム２０を形成する材料としては、例えば、ポリエチレンテレフタレートやポリエチレンナフタレートなどのポリエステル系樹脂、ジアセチルセルロースやトリアセチルセルロースなどのセルロース系樹脂、ポリメチルメタクリレートなどの（メタ）アクリル系樹脂、ポリスチレンやアクリロニトリル／スチレン共重合体、アクリロニトリル／ブタジエン／スチレン共重合体、アクリロニトリル／エチレン／スチレン共重合体、スチレン／マレイミド共重合体、スチレン／無水マレイン酸共重合体などのスチレン系樹脂、ポリカーボネート系樹脂などが挙げられる。また、ノルボルネン系樹脂をはじめとする環状オレフィン系樹脂、ポリエチレン、ポリプロピレン、プロピレン／エチレン共重合体などのオレフィン系樹脂、塩化ビニル系樹脂、ナイロンや芳香族ポリアミドなどのアミド系樹脂、芳香族ポリイミドやポリイミドアミドなどのイミド系樹脂、スルホン系樹脂、ポリエーテルスルホン系樹脂、ポリエーテルエーテルケトン系樹脂、ポリフェニレンスルフィド系樹脂、ビニルアルコール系樹脂、塩化ビニリデン系樹脂、ビニルブチラール系樹脂、ポリオキシメチレン系樹脂、エポキシ系樹脂等を挙げることができ、これらの樹脂のブレンド物からなる高分子フィルムなども、透明保護フィルム２０として用いることができる。これらの中でも、偏光フィルムとの接着の容易さなどを考慮すると、セルロース系樹脂、ポリエステル系樹脂、（メタ）アクリル系樹脂、及びオレフィン系樹脂が好ましい。透明保護フィルム２０は、偏光フィルム１０との貼合に先立って、ケン化処理、コロナ処理、プラズマ処理などを施しておくことが望ましい。 [Transparent protective film]
The transparent protective film 20 laminated on one surface of the polarizing film 10 is preferably one that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. Examples of the material for forming the transparent protective film 20 include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as diacetyl cellulose and triacetyl cellulose, (meth) acrylic resins such as polymethyl methacrylate, and polystyrene. And styrene resins such as acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, acrylonitrile / ethylene / styrene copolymer, styrene / maleimide copolymer, styrene / maleic anhydride copolymer, polycarbonate resin Etc. In addition, cyclic olefin resins such as norbornene resins, olefin resins such as polyethylene, polypropylene, and propylene / ethylene copolymers, vinyl chloride resins, amide resins such as nylon and aromatic polyamide, aromatic polyimide, Imide resins such as polyimide amide, sulfone resins, polyether sulfone resins, polyether ether ketone resins, polyphenylene sulfide resins, vinyl alcohol resins, vinylidene chloride resins, vinyl butyral resins, polyoxymethylene resins An epoxy resin can be used, and a polymer film made of a blend of these resins can also be used as the transparent protective film 20. Among these, cellulose resin, polyester resin, (meth) acrylic resin, and olefin resin are preferable in consideration of easy adhesion to the polarizing film. The transparent protective film 20 is preferably subjected to saponification treatment, corona treatment, plasma treatment and the like prior to bonding with the polarizing film 10.
　透明保護フィルム２０の膜厚は、適宜に決定しうるが、一般には強度や取り扱い性等の作業性などの点より、１～５００μｍ程度である。より好ましくは、１０～２００μｍ、さらに好ましくは２０～１００μｍである。前記の範囲であれば、偏光フィルム１０を機械的に保護し、高温高湿下に曝されても偏光フィルム１０が収縮せず、安定した光学特性を保つことができる。 The film thickness of the transparent protective film 20 can be determined as appropriate, but is generally about 1 to 500 μm from the viewpoint of workability such as strength and handleability. More preferably, it is 10 to 200 μm, and further preferably 20 to 100 μm. If it is the said range, the polarizing film 10 will be protected mechanically, and even if it exposes to high temperature and high humidity, the polarizing film 10 will not shrink | contract and can maintain the stable optical characteristic.
　［第２の接着剤層］
　本発明において、第２の接着剤層とは、上記偏光フィルムと上記位相差フィルムとの接着を担う層である。第２の接着剤層は、活性化エネルギー線（たとえば、紫外線、可視光、電子線、Ｘ線等）の照射または加熱により硬化するエポキシ系樹脂を含有する硬化性のエポキシ系樹脂組成物、または、８０℃の温度において０．１ＭＰａ以上の貯蔵弾性率を示す高弾性粘着剤から形成されている。 [Second adhesive layer]
In the present invention, the second adhesive layer is a layer responsible for adhesion between the polarizing film and the retardation film. The second adhesive layer is a curable epoxy resin composition containing an epoxy resin that is cured by irradiation or heating of activation energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.), or , And formed from a highly elastic pressure-sensitive adhesive having a storage elastic modulus of 0.1 MPa or more at a temperature of 80 ° C.
　（１）　エポキシ系樹脂組成物
　第２の接着剤層の形成に用いられるエポキシ系樹脂組成物は、典型的には、上記硬化性エポキシ系樹脂を主成分とする無溶剤型の樹脂組成物である。かかる接着剤は、上記の偏光フィルムと位相差フィルムとを十分に高い接着強度で貼合することができ、これにより、耐候性に優れた複合偏光板を得ることができる。偏光フィルムと位相差フィルムとの接着は、これらフィルム間に介在する接着剤の塗布層に対して、活性化エネルギー線を照射するか、または加熱し、接着剤に含有される硬化性のエポキシ系樹脂を硬化させることにより行なうことができる。本発明において活性化エネルギー線の照射または熱によるエポキシ系樹脂の硬化は、好ましくは、エポキシ系樹脂のカチオン重合により行われる。なお、本発明においてエポキシ系樹脂とは、分子内に２個以上のエポキシ基を有する化合物を意味する。 (1) Epoxy resin composition The epoxy resin composition used for forming the second adhesive layer is typically a solventless resin composition containing the curable epoxy resin as a main component. is there. Such an adhesive can bond the polarizing film and the retardation film with sufficiently high adhesive strength, thereby obtaining a composite polarizing plate having excellent weather resistance. Adhesion between the polarizing film and the retardation film is performed by irradiating an activation energy ray or heating the coating layer of the adhesive interposed between the films, and a curable epoxy system contained in the adhesive. This can be done by curing the resin. In the present invention, the curing of the epoxy resin by activation energy ray irradiation or heat is preferably performed by cationic polymerization of the epoxy resin. In the present invention, the epoxy resin means a compound having two or more epoxy groups in the molecule.
　本発明において、第２の接着剤層に用いられる硬化性エポキシ系樹脂としては、耐候性や屈折率、カチオン重合性などの観点から、分子内に芳香環を含まないエポキシ系樹脂を用いることが好ましい。このようなエポキシ系樹脂として、水素化エポキシ系樹脂、脂環式エポキシ系樹脂、脂肪族エポキシ系樹脂などが例示できる。 In the present invention, as the curable epoxy resin used for the second adhesive layer, an epoxy resin that does not contain an aromatic ring in the molecule is used from the viewpoint of weather resistance, refractive index, cationic polymerization, and the like. preferable. Examples of such epoxy resins include hydrogenated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.
　（水素化エポキシ系樹脂）
　水素化エポキシ系樹脂は、芳香族エポキシ系樹脂を触媒の存在下、加圧下で選択的に核水素化反応を行なうことにより得ることができる。芳香族エポキシ系樹脂としては、たとえば、ビスフェノールＡのジグリシジルエーテル、ビスフェールＦのジグリシジルエーテル、ビスフェノールＳのジグリシジルエーテルなどのビスフェノール型エポキシ樹脂；フェノールノボラックエポキシ樹脂、クレゾールノボラックエポキシ樹脂、ヒドロキシベンズアルデヒドフェノールノボラックエポキシ樹脂などのノボラック型のエポキシ樹脂；テトラヒドロキシフェニルメタンのグリシジルエーテル、テトラヒドロキシベンゾフェノンのグリシジルエーテル、エポキシ化ポリビニルフェノールなどの多官能型のエポキシ樹脂などが挙げられる。なかでも、水素化エポキシ樹脂として、水素化したビスフェノールＡのグリシジルエーテルを用いることが好ましい。 (Hydrogenated epoxy resin)
The hydrogenated epoxy resin can be obtained by subjecting an aromatic epoxy resin to a nuclear hydrogenation reaction selectively under pressure in the presence of a catalyst. Examples of the aromatic epoxy resin 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, hydroxybenzaldehyde Examples include novolak-type epoxy resins such as phenol novolac epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and epoxidized polyvinylphenol. Among them, it is preferable to use hydrogenated bisphenol A glycidyl ether as the hydrogenated epoxy resin.
　（脂環式エポキシ系樹脂）
　脂環式エポキシ系樹脂とは、脂環式環に結合したエポキシ基を分子内に１個以上有するエポキシ系樹脂を意味する。「脂環式環に結合したエポキシ基」とは、下記式に示される構造における（ＣＨ2）mから１個または複数個の水素原子を取り除いた構造を有する基である。下記式中、ｍは２～５の整数である。 (Alicyclic epoxy resin)
The alicyclic epoxy resin means an epoxy resin having at least one epoxy group bonded to the alicyclic ring in the molecule. The “epoxy group bonded to an alicyclic ring” is a group having a structure in which one or a plurality of hydrogen atoms are removed from (CH 2 ) m in the structure represented by the following formula. In the following formula, m is an integer of 2 to 5.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
　したがって、上記式における（ＣＨ2）m中の１個または複数個の水素原子を取り除いた構造を有する基が他の化学構造を有する基に結合しており、分子内に２個以上のエポキシ基を有する化合物が脂環式エポキシ系樹脂となり得る。（ＣＨ2）m中の１個または複数個の水素原子は、メチル基やエチル基などの直鎖状アルキル基で適宜置換されていてもよい。脂環式エポキシ系樹脂のなかでも、オキサビシクロヘキサン環（上記式においてｍ＝３のもの）や、オキサビシクロヘプタン環（上記式においてｍ＝４のもの）を有するエポキシ系樹脂は、優れた接着性を示すことから好ましく用いられる。以下に、本発明において好ましく用いられる脂環式エポキシ系樹脂を具体的に例示するが、これらの化合物に限定されるものではない。 Accordingly, a group having a structure in which one or more hydrogen atoms in (CH 2 ) m in the above formula are removed is bonded to a group having another chemical structure, and two or more epoxy groups are present in the molecule. A compound having 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) has excellent adhesion. It is preferably used because it exhibits sexiness. Although the alicyclic epoxy resin preferably used in the present invention is specifically exemplified below, it is not limited to these compounds.
　（ａ）下記式（Ｉ）で示されるエポキシシクロヘキシルメチルエポキシシクロヘキサンカルボキシレート類： (A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
（式中、Ｒ1およびＲ2は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表す。）　（ｂ）下記式（ＩＩ）で示されるアルカンジオールのエポキシシクロヘキサンカルボキシレート類： (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) Epoxycyclohexane of alkanediol represented by the following formula (II) Carboxylates:
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
（式中、Ｒ3およびＲ4は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表し、ｎは２～２０の整数を表す。）
　（ｃ）下記式（ＩＩＩ）で示されるジカルボン酸のエポキシシクロヘキシルメチルエステル類： (Wherein 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) Epoxycyclohexylmethyl esters of dicarboxylic acid represented by the following formula (III):
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
（式中、Ｒ5およびＲ6は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表し、ｐは２～２０の整数を表す。）
　（ｄ）下記式（ＩＶ）で示されるポリエチレングリコールのエポキシシクロヘキシルメチルエーテル類： (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):
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000005
（式中、Ｒ7およびＲ8は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表し、ｑは２～１０の整数を表す。）
　（ｅ）下記式（Ｖ）で示されるアルカンジオールのエポキシシクロヘキシルメチルエーテル類： (Wherein R 7 and R 8 independently of each other 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):
Figure JPOXMLDOC01-appb-C000006
Figure JPOXMLDOC01-appb-C000006
（式中、Ｒ9およびＲ10は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表し、ｒは２～２０の整数を表す。）
　（ｆ）下記式（ＶＩ）で示されるジエポキシトリスピロ化合物： (Wherein R 9 and R 10 independently of each other 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):
Figure JPOXMLDOC01-appb-C000007
Figure JPOXMLDOC01-appb-C000007
（式中、Ｒ11及びＲ12は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表す。）
　（ｇ）下記式（ＶＩＩ）で示されるジエポキシモノスピロ化合物： (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):
Figure JPOXMLDOC01-appb-C000008
Figure JPOXMLDOC01-appb-C000008
（式中、Ｒ13およびＲ14は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表す。）
　（ｈ）下記式（ＶＩＩＩ）で示されるビニルシクロヘキセンジエポキシド類： (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):
Figure JPOXMLDOC01-appb-C000009
Figure JPOXMLDOC01-appb-C000009
（式中、Ｒ15は、水素原子または炭素数１～５の直鎖状アルキル基を表す。）
　（ｉ）下記式（ＩＸ）で示されるエポキシシクロペンチルエーテル類： (In the formula, 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):
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000010
（式中、Ｒ16およびＲ17は、互いに独立して、水素原子または炭素数１～５の直鎖状アルキル基を表す。）
　（ｊ）下記式（Ｘ）で示されるジエポキシトリシクロデカン類： (In the formula, 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):
Figure JPOXMLDOC01-appb-C000011
Figure JPOXMLDOC01-appb-C000011
（式中、Ｒ18は、水素原子または炭素数１～５の直鎖状アルキル基を表す。）
　上記例示した脂環式エポキシ系樹脂のなかでも、次の脂環式エポキシ系樹脂は、市販されているか、またはその類似物であって、入手が比較的容易であるなどの理由から、より好ましく用いられる。 (In the formula, 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 more preferable because they are commercially available or similar, and are relatively easy to obtain. Used.
　（Ａ）７－オキサビシクロ［４．１．０］ヘプタン－３－カルボン酸と（７－オキサ－ビシクロ［４．１．０］ヘプト－３－イル）メタノールとのエステル化物（式（Ｉ）において、Ｒ1＝Ｒ2＝Ｈの化合物）、
　（Ｂ）４－メチル－７－オキサビシクロ［４．１．０］ヘプタン－３－カルボン酸と（４－メチル－７－オキサ－ビシクロ［４．１．０］ヘプト－３－イル）メタノールとのエステル化物（式（Ｉ）において、Ｒ1＝４－ＣＨ3、Ｒ2＝４－ＣＨ3の化合物）、
　（Ｃ）７－オキサビシクロ［４．１．０］ヘプタン－３－カルボン酸と１，２－エタンジオールとのエステル化物（式（ＩＩ）において、Ｒ3＝Ｒ4＝Ｈ、ｎ＝２の化合物）、
　（Ｄ）（７－オキサビシクロ［４．１．０］ヘプト－３－イル）メタノールとアジピン酸とのエステル化物（式（ＩＩＩ）において、Ｒ5＝Ｒ6＝Ｈ、ｐ＝４の化合物）、
　（Ｅ）（４－メチル－７－オキサビシクロ［４．１．０］ヘプト－３－イル）メタノールとアジピン酸とのエステル化物（式（ＩＩＩ）において、Ｒ5＝４－ＣＨ3、Ｒ6＝４－ＣＨ3、ｐ＝４の化合物）、
　（Ｆ）（７－オキサビシクロ［４．１．０］ヘプト－３－イル）メタノールと１，２－エタンジオールとのエーテル化物（式（Ｖ）において、Ｒ9＝Ｒ10＝Ｈ、ｒ＝２の化合物）。 (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 Esterified compounds of the formula (compounds of formula (I) where R 1 = 4-CH 3 , R 2 = 4-CH 3 ),
(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 = 2 compounds).
　（脂肪族エポキシ系樹脂）
　脂肪族エポキシ系樹脂としては、脂肪族多価アルコールまたはそのアルキレンオキサイド付加物のポリグリシジルエーテルを挙げることができる。これらの例としては、１，４－ブタンジオールのジグリシジルエーテル、１，６－ヘキサンジオールのジグリシジルエーテル、グリセリンのトリグリシジルエーテル、トリメチロールプロパンのトリグリシジルエーテル、ポリエチレングリコールのジグリシジルエーテル、プロピレングリコールのジグリシジルエーテル、エチレングリコールやプロピレングリコール、グリセリン等の脂肪族多価アルコールに１種または２種以上のアルキレンオキサイド（エチレンオキサイドやプロピレンオキサイド）を付加することにより得られるポリエーテルポリオールのポリグリシジルエーテルなどが挙げられる。 (Aliphatic epoxy resin)
Examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Examples include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, propylene Polyglycidyl of a polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as diglycidyl ether of glycol, ethylene glycol, propylene glycol or glycerin Examples include ether.
　本発明において、エポキシ系樹脂は、１種のみを単独で使用してもよいし、あるいは２種以上を併用してもよい。本発明で使用するエポキシ系樹脂のエポキシ当量は、通常３０～３，０００ｇ／当量、好ましくは５０～１，５００ｇ／当量の範囲内である。エポキシ当量が３０ｇ／当量を下回ると、硬化後の複合偏光板の可撓性が低下したり、接着強度が低下したりする可能性がある。一方、３，０００ｇ／当量を超えると、接着剤に含有される他の成分との相溶性が低下する可能性がある。 In the present invention, only one epoxy resin may be used alone, or two or more epoxy resins may be used in combination. The epoxy equivalent of the epoxy resin used in the present invention 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.
　本発明においては、反応性の観点から、硬化性エポキシ系樹脂組成物の硬化反応としてカチオン重合が好ましく用いられる。そのためには、硬化性エポキシ系樹脂組成物にカチオン重合開始剤を配合するのが好ましい。カチオン重合開始剤は、可視光線、紫外線、Ｘ線、電子線等の活性化エネルギー線の照射または加熱によって、カチオン種またはルイス酸を発生し、エポキシ基の重合反応を開始させる。いずれのタイプのカチオン重合開始剤であっても、潜在性が付与されていることが、作業性の観点から好ましい。以下、活性化エネルギー線の照射によりカチオン種またはルイス酸を発生し、エポキシ基の重合反応を開始させるカチオン重合開始剤を「光カチオン重合開始剤」といい、熱によりカチオン種またはルイス酸を発生し、エポキシ基の重合反応を開始させるカチオン重合開始剤を「熱カチオン重合開始剤」という。 In the present invention, from the viewpoint of reactivity, cationic polymerization is preferably used as the curing reaction of the curable epoxy resin composition. For that purpose, it is preferable to mix | blend a cationic polymerization initiator with a curable epoxy resin composition. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiating or heating an activation energy ray such as visible light, ultraviolet ray, X-ray, electron beam, etc., and starts an epoxy group polymerization reaction. Regardless of the type of cationic polymerization initiator, it is preferable from the viewpoint of workability that latency is imparted. Hereinafter, a cationic polymerization initiator that generates a cationic species or Lewis acid upon irradiation of activation energy rays and initiates a polymerization reaction of an epoxy group is called a “photo cationic polymerization initiator”, and generates a cationic species or Lewis acid by heat. The cationic polymerization initiator that initiates the polymerization reaction of the epoxy group is referred to as a “thermal cationic polymerization initiator”.
　（光カチオン重合開始剤）
　光カチオン重合開始剤を用い、活性化エネルギー線の照射により接着剤の硬化を行なう方法は、常温での硬化が可能となり、偏光フィルムの耐熱性あるいは膨張による歪を考慮する必要が減少し、位相差フィルムと偏光フィルムとを良好に接着できる点において有利である。また、光カチオン重合開始剤は、光で触媒的に作用するため、エポキシ系樹脂に混合しても保存安定性や作業性に優れる。 (Photocationic polymerization initiator)
The method of curing the adhesive by irradiating with an activation energy ray using a cationic photopolymerization initiator enables curing at room temperature, reducing the need to consider the heat resistance of the polarizing film or distortion due to expansion. This is advantageous in that the phase difference film and the polarizing film can be favorably bonded. In addition, since the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy resin.
　光カチオン重合開始剤としては、特に限定されないが、たとえば、芳香族ジアゾニウム塩、芳香族ヨードニウム塩、芳香族スルホニウム塩などのオニウム塩、鉄－アレン錯体などを挙げることができる。 The photocationic polymerization initiator is not particularly limited, and examples thereof include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, and iron-allene complexes.
　芳香族ジアゾニウム塩としては、たとえば、ベンゼンジアゾニウム　ヘキサフルオロアンチモネート、ベンゼンジアゾニウム　ヘキサフルオロホスフェート、ベンゼンジアゾニウム　ヘキサフルオロボレートなどが挙げられる。また、芳香族ヨードニウム塩としては、たとえば、ジフェニルヨードニウム　テトラキス（ペンタフルオロフェニル）ボレート、ジフェニルヨードニウム　ヘキサフルオロホスフェート、ジフェニルヨードニウム　ヘキサフルオロアンチモネート、ジ（４－ノニルフェニル）ヨードニウム　ヘキサフルオロホスフェートなどが挙げられる。 Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, benzenediazonium hexafluoroborate, and the like. Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.
　芳香族スルホニウム塩としては、たとえば、トリフェニルスルホニウム　ヘキサフルオロホスフェート、トリフェニルスルホニウム　ヘキサフルオロアンチモネート、トリフェニルスルホニウム　テトラキス（ペンタフルオロフェニル）ボレート、４，４’－ビス（ジフェニルスルホニオ）ジフェニルスルフィド　ビス（ヘキサフルオロホスフェート）、４，４’－ビス（ジ（β－ヒドロキシエトキシ）フェニルスルホニオ）ジフェニルスルフィド　ビス（ヘキサフルオロアンチモネート）、４，４’－ビス（ジ（β－ヒドロキシエトキシ）フェニルスルホニオ）ジフェニルスルフィド　ビス（ヘキサフルオロホスフェート）、７－（ジ（ｐ－トルイル）スルホニオ）－２－イソプロピルチオキサントン　ヘキサフルオロアンチモネート、７－（ジ（ｐ－トルイル）スルホニオ）－２－イソプロピルチオキサントン　テトラキス（ペンタフルオロフェニル）ボレート、４－フェニルカルボニル－４’－ジフェニルスルホニオ－ジフェニルスルフィド　ヘキサフルオロホスフェート、４－（ｐ－ｔｅｒｔ－ブチルフェニルカルボニル）－４’－ジフェニルスルホニオ－ジフェニルスルフィド　ヘキサフルオロアンチモネート、４－（ｐ－ｔｅｒｔ－ブチルフェニルカルボニル）－４’－ジ（ｐ－トルイル）スルホニオ－ジフェニルスルフィド　テトラキス（ペンタフルオロフェニル）ボレートなどが挙げられる。 Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis (diphenylsulfonio) diphenyl sulfide 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-butylphenyl) Carbonyl) -4′-diphenylsulfonio-diphenyl sulfide, hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4′-di (p-toluyl) sulfonio-diphenyl sulfide, tetrakis (pentafluorophenyl) borate, etc. Is mentioned.
　また、鉄－アレン錯体としては、たとえば、キシレン－シクロペンタジエニル鉄（ＩＩ）ヘキサフルオロアンチモネート、クメン－シクロペンタジエニル鉄（ＩＩ）ヘキサフルオロホスフェート、キシレン－シクロペンタジエニル鉄（ＩＩ）－トリス（トリフルオロメチルスルホニル）メタナイドなどが挙げられる。 Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) methanide and the like.
　これらの光カチオン重合開始剤のそれぞれは単独で使用してもよいし、別の１種以上と混合して使用してもよい。これらのなかでも特に芳香族スルホニウム塩は、３００ｎｍ以上の波長領域でも紫外線吸収特性を有することから、硬化性に優れ、良好な機械強度や接着強度を有する硬化物を与えることができるため、好ましく用いられる。 Each of these photocationic polymerization initiators may be used alone or in combination with one or more other types. 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 therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.
　これらの開始剤は、市販品を容易に入手することが可能であり、例えば、それぞれ商品名で、「カヤラッド（登録商標）ＰＣＩ－２２０」、「カヤラッド（登録商標）ＰＣＩ－６２０」（以上、日本化薬株式会社製）、「ＵＶＩ－６９９０」（ユニオンカーバイド社製）、「アデカオプトマー（登録商標）ＳＰ－１５０」、「アデカオプトマー（登録商標）ＳＰ－１７０」（以上、株式会社ＡＤＥＫＡ製）、「ＣＩ－５１０２」、「ＣＩＴ－１３７０」、「ＣＩＴ－１６８２」、「ＣＩＰ－１８６６Ｓ」、「ＣＩＰ－２０４８Ｓ」、「ＣＩＰ－２０６４Ｓ」（以上、日本曹達株式会社製）、「ＤＰＩ－１０１」、「ＤＰＩ－１０２」、「ＤＰＩ－１０３」、「ＤＰＩ－１０５」、「ＭＰＩ－１０３」、「ＭＰＩ－１０５」、「ＢＢＩ－１０１」、「ＢＢＩ－１０２」、「ＢＢＩ－１０３」、「ＢＢＩ－１０５」、「ＴＰＳ－１０１」、「ＴＰＳ－１０２」、「ＴＰＳ－１０３」、「ＴＰＳ－１０５」、「ＭＤＳ－１０３」、「ＭＤＳ－１０５」、「ＤＴＳ－１０２」、「ＤＴＳ－１０３」（以上、みどり化学株式会社製）、「ＰＩ－２０７４」（ローディア社製）などを挙げることができる。 These initiators can be easily obtained as commercial products. For example, “Kayarad (registered trademark) PCI-220” and “Kayarad (registered trademark) PCI-620” (above, Nippon Kayaku Co., Ltd.), "UVI-6990" (Union Carbide), "Adekaoptomer (registered trademark) SP-150", "Adekaoptomer (registered trademark) SP-170" ADEKA), “CI-5102”, “CIT-1370”, “CIT-1682”, “CIP-1866S”, “CIP-2048S”, “CIP-2064S” (above, manufactured by Nippon Soda Co., Ltd.), “ DPI-101 "," DPI-102 "," DPI-103 "," DPI-105 "," MPI-103 "," MPI-105 "," BBI-10 " ”,“ BBI-102 ”,“ BBI-103 ”,“ BBI-105 ”,“ TPS-101 ”,“ TPS-102 ”,“ TPS-103 ”,“ TPS-105 ”,“ MDS-103 ”, “MDS-105”, “DTS-102”, “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), and the like.
　光カチオン重合開始剤の配合量は、硬化性エポキシ系樹脂１００重量部に対して、通常０．５～２０重量部であり、好ましくは１重量部以上、また好ましくは１５重量部以下である。その量がエポキシ系樹脂１００重量部あたり０．５重量部を下回ると、硬化が不十分になり、機械強度や接着強度が低下する傾向となる。また、その量がエポキシ系樹脂１００重量部あたり２０重量部を越えると、硬化物中のイオン性物質が増加することで硬化物の吸湿性が高くなり、耐久性能が低下する可能性があるので、好ましくない。 The amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less with respect to 100 parts by weight of the curable epoxy resin. When the amount is less than 0.5 parts by weight per 100 parts by weight of the epoxy resin, curing becomes insufficient, and mechanical strength and adhesive strength tend to decrease. Moreover, when the amount exceeds 20 parts by weight per 100 parts by weight of the epoxy resin, the ionic substance in the cured product increases, so that the hygroscopic property of the cured product increases and the durability performance may be reduced. It is not preferable.
　（光増感剤）
　光カチオン重合開始剤を用いる場合、接着剤である硬化性エポキシ系樹脂組成物は、必要に応じて、さらに光増感剤を含有することができる。光増感剤を使用することで、カチオン重合の反応性が向上し、硬化物の機械的強度や接着強度を向上させることができる。光増感剤としては、たとえば、カルボニル化合物、有機硫黄化合物、過硫化物、レドックス系化合物、アゾおよびジアゾ化合物、ハロゲン化合物、光還元性色素などが挙げられる。光増感剤のより具体的な例は、ベンゾインメチルエーテル、ベンゾインイソプロピルエーテル、α，α－ジメトキシ－α－フェニルアセトフェノンなどのベンゾイン誘導体；ベンゾフェノン、２，４－ジクロロベンゾフェノン、ｏ－ベンゾイル安息香酸メチル、４，４’－ビス（ジメチルアミノ）ベンゾフェノン、４，４’－ビス（ジエチルアミノ）ベンゾフェノンなどのベンゾフェノン誘導体；２－クロロチオキサントン、２－イソプロピルチオキサントンなどのチオキサントン誘導体；２－クロロアントラキノン、２－メチルアントラキノンなどのアントラキノン誘導体；Ｎ－メチルアクリドン、Ｎ－ブチルアクリドンなどのアクリドン誘導体；その他、α，α－ジエトキシアセトフェノン、ベンジル、フルオレノン、キサントン、ウラニル化合物、ハロゲン化合物などを含むが、これらに限定されるものではない。また、これらの光増感剤のそれぞれは単独で使用してもよいし、別の１種以上と混合して使用してもよい。光増感剤は、硬化性エポキシ系樹脂組成物１００重量部中、０．１～２０重量部の範囲内で含有されることが好ましい。 (Photosensitizer)
When using a photocationic polymerization initiator, the curable epoxy resin composition that is an adhesive may further contain a photosensitizer, if 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. More specific examples of photosensitizers include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate Benzophenone derivatives such as 4,4′-bis (dimethylamino) benzophenone and 4,4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2-chloroanthraquinone, 2-methyl Anthraquinone derivatives such as anthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; others, α, α-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranylated Things, including a halogen compound, but is not limited thereto. In addition, each of these photosensitizers may be used alone, or may be used as a mixture with another one or more. The photosensitizer is preferably contained within a range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.
　（熱カチオン重合開始剤）
　一方、熱カチオン重合開始剤としては、ベンジルスルホニウム塩、チオフェニウム塩、チオラニウム塩、ベンジルアンモニウム、ピリジニウム塩、ヒドラジニウム塩、カルボン酸エステル、スルホン酸エステル、アミンイミドなどを挙げることができる。これらの開始剤は、市販品を容易に入手することが可能であり、例えば、いずれも商品名で、「アデカオプトンＣＰ７７」および「アデカオプトンＣＰ６６」（以上、株式会社ＡＤＥＫＡ製）、「ＣＩ－２６３９」および「ＣＩ－２６２４」（以上、日本曹達株式会社製）、「サンエイド（登録商標）ＳＩ－６０Ｌ」、「サンエイド（登録商標）ＳＩ－８０Ｌ」および「サンエイド（登録商標）ＳＩ－１００Ｌ」（以上、三新化学工業株式会社製）などが挙げられる。 (Thermal cationic polymerization initiator)
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 initiators can be easily obtained as commercial products. For example, “ADEKA OPTON CP77” and “ADEKA OPTON CP66” (manufactured by ADEKA, Inc.), “CI-2539” are trade names. "CI-2624" (manufactured by Nippon Soda Co., Ltd.), "Sun-Aid (registered trademark) SI-60L", "Sun-Aid (registered trademark) SI-80L" and "Sun-Aid (registered trademark) SI-100L" (and above) , Manufactured by Sanshin Chemical Industry Co., Ltd.).
　接着剤に含有されるエポキシ系樹脂は、光カチオン重合または熱カチオン重合のいずれかにより硬化してもよいし、あるいは、光カチオン重合および熱カチオン重合の双方により硬化してもよい。後者の場合、光カチオン重合開始剤と熱カチオン重合開始剤とを併用することが好ましい。 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.
　（重合促進剤）
　本発明において接着剤として用いる硬化性エポキシ系樹脂組成物は、さらにオキセタン類やポリオール類など、カチオン重合を促進する化合物を含有してもよい。 (Polymerization accelerator)
The curable epoxy resin composition used as an adhesive in the present invention may further contain a compound that promotes cationic polymerization, such as oxetanes and polyols.
　オキセタン類は、分子内に４員環エーテルを有する化合物であり、例えば、３－エチル－３－ヒドロキシメチルオキセタン、１，４－ビス（（３－エチル－３－オキセタニル）メトキシメチル）ベンゼン、３－エチル－３－（フェノキシメチル）オキセタン、ジ（（３－エチル－３－オキセタニル）メチル）エーテル、３－エチル－３－（２－エチルヘキシロキシメチル）オキセタン、フェノールノボラックオキセタンなどが挙げられる。これらのオキセタン化合物は市販品を容易に入手することが可能であり、例えば、いずれも商品名で、「アロンオキセタン（登録商標）ＯＸＴ－１０１」、「アロンオキセタン（登録商標）ＯＸＴ－１２１」、「アロンオキセタン（登録商標）ＯＸＴ－２１１」、「アロンオキセタン（登録商標）ＯＸＴ－２２１」、「アロンオキセタン（登録商標）ＯＸＴ－２１２」（以上、東亞合成株式会社製）などを挙げることができる。また、これらのオキセタン環含有化合物は、硬化性エポキシ系樹脂組成物中で、通常５～９５重量％、好ましくは３０～７０重量％の割合で使用される。 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 oxetane compounds can be easily obtained as commercial products. For example, all of these oxetane compounds are trade names such as “Aron oxetane (registered trademark) OXT-101”, “Aron oxetane (registered trademark) OXT-121”, “Aron Oxetane (registered trademark) OXT-211”, “Aron Oxetane (registered trademark) OXT-221”, “Aron Oxetane (registered trademark) OXT-212” (above, manufactured by Toagosei Co., Ltd.) . These oxetane ring-containing compounds are generally used in a proportion of 5 to 95% by weight, preferably 30 to 70% by weight, in the curable epoxy resin composition.
　ポリオール類としては、フェノール性水酸基以外の酸性基が存在しないものが好ましく、例えば、水酸基以外の官能基を有しないポリオール化合物、ポリエステルポリオール化合物、ポリカプロラクトンポリオール化合物、フェノール性水酸基を有するポリオール化合物、ポリカーボネートポリオールなどを挙げることができる。これらのポリオール類の分子量は、通常４８以上、好ましくは６２以上、さらに好ましくは１００以上、また好ましくは１，０００以下である。これらポリオール類の配合量は、エポキシ系樹脂組成物中で、通常５０重量％以下、好ましくは３０重量％以下である。 As the polyols, those having no acidic groups 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. The blending amount of these polyols is usually 50% by weight or less, preferably 30% by weight or less in the epoxy resin composition.
　さらに、硬化性エポキシ系樹脂組成物には、本発明の効果を損なわない限り、その他の添加剤、例えば、イオントラップ剤、酸化防止剤、連鎖移動剤、増感剤、粘着付与剤、熱可塑性樹脂、充填剤、流動調整剤、可塑剤、消泡剤などを配合することができる。イオントラップ剤としては、たとえば、粉末状のビスマス系、アンチモン系、マグネシウム系、アルミニウム系、カルシウム系、チタン系およびこれらの混合系などの無機化合物が挙げられ、酸化防止剤としては、たとえば、ヒンダードフェノール系酸化防止剤などが挙げられる。 Furthermore, the curable epoxy resin composition has other additives such as an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic as long as the effects of the present invention are not impaired. Resins, fillers, flow regulators, plasticizers, antifoaming agents, and the like can be blended. Examples of the ion trapping agent include powdery bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based and mixed compounds thereof. Examples of the antioxidant include hinders. Examples include dophenol antioxidants.
　本発明に用いる硬化性エポキシ系樹脂組成物は、溶剤成分を実質的に含まない無溶剤型の組成物であることが好ましく、無溶剤型であることにより乾燥・養生の工程が短縮できるため、製造工程が短縮され複合偏光板の生産性を向上させることができる。ただし、各塗工方式には各々最適な粘度範囲があるため、粘度調整のために溶剤を含有させてもよい。溶剤としては、偏光フィルムの光学性能を低下させることなく、硬化性エポキシ系樹脂を良好に溶解するものを用いることが好ましく、特に限定されないが、たとえば、トルエンに代表される炭化水素類、酢酸エチルに代表されるエステル類などの有機溶剤を挙げることができる。 The curable epoxy resin composition used in the present invention is preferably a solventless composition that does not substantially contain a solvent component, and because it is solventless, the drying and curing processes can be shortened. A manufacturing process is shortened and productivity of a composite polarizing plate can be improved. However, since each coating method has an optimum viscosity range, a solvent may be included for viscosity adjustment. The solvent is preferably one that dissolves the curable epoxy resin well without degrading the optical performance of the polarizing film, and is not particularly limited. For example, hydrocarbons typified by toluene, ethyl acetate And organic solvents such as esters represented by
　第２の接着剤層の厚さは、通常５０μｍ以下、好ましくは２０μｍ以下、さらに好ましくは１０μｍ以下である。 The thickness of the second adhesive layer is usually 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.
　（偏光フィルムと位相差フィルムの積層）
　以上のような硬化性エポキシ系樹脂を含有する組成物を、偏光フィルムあるいは位相差フィルムの接着面、またはこれら双方の接着面に塗工した後、接着剤の塗工された面で貼合し、活性化エネルギー線を照射するか、または加熱することにより、未硬化の硬化性エポキシ系樹脂組成物を硬化させることによって、偏光フィルムと位相差フィルムとを該組成物の硬化物層からなる第２の接着剤層を介して貼合することができる。硬化性エポキシ系樹脂組成物の塗工方法に特別な限定はなく、たとえば、ドクターブレード、ワイヤーバー、ダイコーター、カンマコーター、グラビアコーターなど、種々の塗工方式が利用できる。 (Lamination of polarizing film and retardation film)
The composition containing the curable epoxy resin as described above is applied to the adhesive surface of the polarizing film or the retardation film, or the adhesive surface of both, and then bonded to the adhesive-coated surface. The polarizing film and the retardation film are formed of a cured product layer of the composition by curing the uncured curable epoxy resin composition by irradiating with activation energy rays or heating. It can be bonded through two adhesive layers. There is no special limitation in the coating method of a curable epoxy resin composition, For example, various coating systems, such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, can be utilized.
　活性化エネルギー線の照射により硬化性エポキシ系樹脂組成物の硬化を行なう場合、用いる光源は、特に限定されないが、波長４００ｎｍ以下に発光分布を有する、たとえば、低圧水銀灯、中圧水銀灯、高圧水銀灯、超高圧水銀灯、ケミカルランプ、ブラックライトランプ、マイクロウェーブ励起水銀灯、メタルハライドランプなどを用いることができる。硬化性エポキシ系樹脂組成物への光照射強度は、該組成物ごとに異なり得るが、光カチオン重合開始剤の活性化に有効な波長領域の照射強度が０．１～１００ｍＷ／ｃｍ2であることが好ましい。硬化性エポキシ系樹脂組成物への光照射強度が０．１ｍＷ／ｃｍ2未満であると、反応時間が長くなりすぎ、１００ｍＷ／ｃｍ2を超えると、ランプから輻射される熱および硬化性エポキシ系樹脂組成物の重合時の発熱により、硬化性エポキシ系樹脂組成物の黄変や偏光フィルムの劣化を生じる可能性がある。硬化性エポキシ系樹脂組成物への光照射時間は、該組成物ごとに制御されるものであって、やはり特に限定されないが、照射強度と照射時間との積として表される積算光量が１０～５，０００ｍＪ／ｃｍ2となるように設定されることが好ましい。硬化性エポキシ系樹脂組成物への積算光量が１０ｍＪ／ｃｍ2未満であると、光カチオン重合開始剤由来の活性種の発生が十分でなく、接着剤の硬化が不十分となる可能性がある。また、積算光量が５，０００ｍＪ／ｃｍ2を超えると、照射時間が非常に長くなり、生産性の点では不利なものとなる。 When curing the curable epoxy resin composition by irradiation with an activation energy ray, the light source used is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, such as a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, An ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, or the like can be used. The light irradiation intensity to the curable epoxy resin composition may vary from composition to composition, but the irradiation intensity in the wavelength region effective for activating the photocationic polymerization initiator is 0.1 to 100 mW / cm 2 . It is preferable. When the light irradiation intensity to the curable epoxy resin composition is less than 0.1 mW / cm 2 , the reaction time becomes too long, and when it exceeds 100 mW / cm 2 , the heat radiated from the lamp and the curable epoxy system The heat generated during polymerization of the resin composition may cause yellowing of the curable epoxy resin composition and deterioration of the polarizing film. The light irradiation time to the curable epoxy resin composition is controlled for each composition and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 10 times. It is preferably set to be 5,000 mJ / cm 2 . When the integrated light quantity to the curable epoxy resin composition 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 is disadvantageous in terms of productivity.
　熱により重合を行う場合は、一般的に知られた方法で加熱することができ、その条件なども特に限定されないが、通常、硬化性エポキシ系樹脂組成物に配合された熱カチオン重合開始剤がカチオン種やルイス酸を発生する温度以上で加熱が行われ、通常５０～２００℃にて実施される。 When polymerization is carried out by heat, it can be heated by a generally known method, and the conditions thereof are not particularly limited, but usually a thermal cationic polymerization initiator blended in the curable epoxy resin composition is used. Heating is performed at a temperature higher than the temperature at which cationic species and Lewis acid are generated, and it is usually performed at 50 to 200 ° C.
　活性化エネルギー線の照射または加熱のいずれの条件で硬化させる場合でも、偏光フィルムの偏光度、透過率および色相、透明保護フィルムの透明性、ならびに位相差フィルムの位相差特性などの複合偏光板の諸機能が低下しない範囲で硬化させることが好ましい。硬化性エポキシ系樹脂組成物からなる第２の接着剤層の厚さは、通常、５０μｍ以下、好ましくは２０μｍ以下、さらに好ましくは１０μｍ以下ある。 Even when cured under the conditions of irradiation of activation energy rays or heating, the polarization of the polarizing film, transmittance and hue, transparency of the transparent protective film, and retardation characteristics of the retardation film, etc. It is preferable to cure within a range in which various functions do not deteriorate. The thickness of the 2nd adhesive bond layer which consists of a curable epoxy resin composition is 50 micrometers or less normally, Preferably it is 20 micrometers or less, More preferably, it is 10 micrometers or less.
　（２）　高弾性粘着剤
　次に、本発明において、位相差フィルムと偏光フィルムの貼合に用いられる第２の接着剤として高弾性粘着剤を用いる場合について以下に詳述する。高弾性粘着剤は、温度８０℃での貯蔵弾性率が０．１ＭＰａ以上であり、好ましくは０．１５ＭＰａ～１０ＭＰａである。また、この高弾性粘着剤の２３℃の温度における貯蔵弾性率は０．１ＭＰａ以上であることが好ましく、さらに好ましくは０．２～１０ＭＰａである。 (2) High elastic adhesive Next, in this invention, the case where a high elastic adhesive is used as a 2nd adhesive agent used for bonding of retardation film and a polarizing film is explained in full detail below. The high elastic pressure-sensitive adhesive has a storage elastic modulus at a temperature of 80 ° C. of 0.1 MPa or more, preferably 0.15 MPa to 10 MPa. Further, the storage elastic modulus at a temperature of 23 ° C. of this highly elastic pressure-sensitive adhesive is preferably 0.1 MPa or more, more preferably 0.2 to 10 MPa.
　（貯蔵弾性率）
　本発明において、貯蔵弾性率（動的弾性率）とは、一般的に用いられる粘弾性の用語を意味するものであるが、試料に時間によって変化（振動）する歪みまたは応力を与えて、それによって発生する応力または歪みを測定することにより、試料の力学的な性質を測定する方法（動的粘弾性測定）によって求められる値であり、歪みを応力と同位相と位相が９０度ずれた２成分の波に分けたとき、振動応力と同位相にある弾性率である。 (Storage modulus)
In the present invention, the storage elastic modulus (dynamic elastic modulus) is a commonly used term of viscoelasticity, but gives a sample a strain or stress that changes (vibrates) with time, and Is a value obtained by a method of measuring the mechanical properties of a sample (dynamic viscoelasticity measurement) by measuring the stress or strain generated by the stress, and the strain is in phase with the stress and the phase is shifted by 90 degrees. When divided into component waves, the elastic modulus is in phase with the vibrational stress.
　貯蔵弾性率は、市販の粘弾性測定装置、例えば後掲の実施例に示すような動的粘弾性測定装置（Dynamic　Analyzer　RDA　II：Reometric社製）を用いて測定することができる。粘弾性測定装置の温度制御には、循環恒温槽、電気ヒーター、ペルチェ素子等の種々公知の温度制御デバイスが用いられており、これによって測定時の温度を設定することができる。 The storage elastic modulus can be measured using a commercially available viscoelasticity measuring device, for example, a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by Reometric) as shown in the examples described later. For the temperature control of the viscoelasticity measuring apparatus, various known temperature control devices such as a circulating thermostat, an electric heater, a Peltier element, and the like are used, and thereby the temperature at the time of measurement can be set.
　なお、貯蔵弾性率は一般的に温度が高い条件ほど低くなる傾向があるため、８０℃で測定した材料の貯蔵弾性率が０．１ＭＰａ以上であれば、通常は２３℃で測定した同じ材料の貯蔵弾性率はそれ以上の値を示す。 In addition, since the storage elastic modulus generally tends to be lower as the temperature is higher, if the storage elastic modulus of the material measured at 80 ° C. is 0.1 MPa or more, usually the same material measured at 23 ° C. A storage elastic modulus shows the value beyond it.
　通常の画像表示装置又はそれ用の光学フィルムに用いられている粘着剤は、その貯蔵弾性率が高々０．１ＭＰａ程度であり、それに比べ、本発明で規定する粘着剤層（第２の接着剤層）の貯蔵弾性率は上述のような高い値となっている。このような高い貯蔵弾性率を示す、すなわち硬い粘着剤を用いることにより、高温環境下に置かれたときや、高温環境と低温環境が繰り返されたときの凝集力不足を補うことができ、そのときに発生する偏光フィルムの収縮に伴う寸法変化を小さく抑えることが可能となる。すなわち、本発明の複合偏光板は良好な耐久性を有し、特に偏光フィルムと位相差フィルムの剥離が抑えられる。 The pressure-sensitive adhesive used in a normal image display device or an optical film therefor has a storage elastic modulus of at most about 0.1 MPa, and in comparison with that, a pressure-sensitive adhesive layer (second adhesive) defined in the present invention. The storage elastic modulus of the layer is a high value as described above. Such a high storage modulus, that is, by using a hard pressure-sensitive adhesive, can compensate for a lack of cohesive force when placed in a high temperature environment or when a high temperature environment and a low temperature environment are repeated. It becomes possible to suppress the dimensional change accompanying the shrinkage | contraction of the polarizing film which generate | occur | produces sometimes. That is, the composite polarizing plate of the present invention has good durability, and in particular, peeling of the polarizing film and the retardation film can be suppressed.
　本発明に用いる高弾性粘着剤としては、例えば、アクリル系ポリマーや、シリコーン系ポリマー、ポリエステル、ポリウレタン、ポリエーテルなどをベースポリマーとするもので構成することができる。なかでも、アクリル系ポリマーのように、光学的な透明性に優れ、適度の濡れ性や凝集力を保持し、基材との接着性にも優れ、さらには耐候性や耐熱性などを有し、加熱や加湿の条件下で浮きや剥がれ等の剥離問題を生じないものを選択して用いることが好ましい。アクリル系ポリマーにおいては、メチル基やエチル基、ブチル基等の炭素数が２０以下のアルキル基を有するアクリル酸のアルキルエステルと、（メタ）アクリル酸や（メタ）アクリル酸ヒドロキシエチルなどからなる官能基含有アクリル系モノマーとを、ガラス転移温度が好ましくは２５℃以下、さらに好ましくは０℃以下となるように配合し重合して得られる、重量平均分子量が１０万以上のアクリル系共重合体が、ベースポリマーとして有用である。 The high-elasticity adhesive used in the present invention can be composed of, for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether, or the like as a base polymer. Above all, like acrylic polymer, it has excellent optical transparency, retains appropriate wettability and cohesion, has excellent adhesion to substrates, and has weather resistance and heat resistance. It is preferable to select and use one that does not cause peeling problems such as floating and peeling under the conditions of heating and humidification. In the acrylic polymer, a functional group comprising an alkyl ester of acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, or a butyl group, and (meth) acrylic acid or hydroxyethyl (meth) acrylate. An acrylic copolymer having a weight average molecular weight of 100,000 or more, obtained by blending and polymerizing a group-containing acrylic monomer with a glass transition temperature of preferably 25 ° C. or lower, more preferably 0 ° C. or lower. Useful as a base polymer.
　アクリル系ポリマーとしては、特に限定されるものではないが、（メタ）アクリル酸ブチル、（メタ）アクリル酸エチル、（メタ）アクリル酸イソオクチル、（メタ）アクリル酸２－エチルヘキシル等の（メタ）アクリル酸エステル系ベースポリマーや、これらの（メタ）アクリル酸エステルを２種類以上用いた共重合系ベースポリマーが好適に用いられる。 The acrylic polymer is not particularly limited, but (meth) acrylic such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. An acid ester base polymer and a copolymer base polymer using two or more of these (meth) acrylic esters are preferably used.
　また、これらのベースポリマーには、極性モノマーが共重合されていてもよい。極性モノマーとしては、例えば、（メタ）アクリル酸、（メタ）アクリル酸２－ヒドロキシプロピル、（メタ）アクリル酸２－ヒドロキシエチル、（メタ）アクリルアミド、２－Ｎ，Ｎ－ジメチルアミノエチル（メタ）アクリレート、グリシジル（メタ）アクリレートなどの、カルボキシル基、水酸基、アミド基、アミノ基、エポキシ基などの極性官能基を有するモノマーを挙げることができる。 Further, polar monomers may be copolymerized with these base polymers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Mention may be made of monomers having polar functional groups such as carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, such as acrylates and glycidyl (meth) acrylates.
　これらのアクリル系ポリマーは、単独でも粘着剤として使用可能であるが、粘着剤には通常、架橋剤が配合される。架橋剤としては、２価または多価金属イオンであって、カルボキシル基との間でカルボン酸金属塩を形成するもの、ポリアミン化合物であって、カルボキシル基との間でアミド結合を形成するもの、ポリエポキシ化合物やポリオール化合物であって、カルボキシル基との間でエステル結合を形成するもの、ポリイソシアネート化合物であって、カルボキシル基との間でカルバミド結合を形成するものなどが例示される。なかでもポリイソシアネート化合物が、有機系架橋剤として広く使用されている。 These acrylic polymers can be used alone as a pressure-sensitive adhesive, but a crosslinking agent is usually added to the pressure-sensitive adhesive. As the crosslinking agent, a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group, Examples include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form a carbamide bond with a carboxyl group. Of these, polyisocyanate compounds are widely used as organic crosslinking agents.
　本発明において、第２の接着剤層を形成する高弾性粘着剤の貯蔵弾性率を高い値にするためには、例えば、上述の粘着剤成分に、オリゴマー、具体的にはウレタンアクリレート系のオリゴマーを配合することが好ましい。さらに、このようなウレタンアクリレート系オリゴマーを配合した粘着剤にエネルギー線を照射して硬化させたものを用いることが、高い貯蔵弾性率を示すようになる点で好ましい。ウレタンアクリレート系オリゴマーが配合された粘着剤、あるいは、それを支持フィルム（セパレータ）上に塗工し紫外線硬化させたセパレータ付き粘着剤は、公知であり、粘着剤メーカーから入手できる。 In the present invention, in order to increase the storage elastic modulus of the high-elastic pressure-sensitive adhesive forming the second adhesive layer, for example, the above-mentioned pressure-sensitive adhesive component may be an oligomer, specifically a urethane acrylate oligomer. Is preferably blended. Furthermore, it is preferable to use a pressure-sensitive adhesive containing such a urethane acrylate oligomer, which is cured by irradiating energy rays, so as to exhibit a high storage elastic modulus. A pressure-sensitive adhesive containing a urethane acrylate oligomer or a pressure-sensitive adhesive with a separator obtained by coating it on a support film (separator) and curing it with ultraviolet rays is known and available from pressure-sensitive adhesive manufacturers.
　本発明の高弾性粘着剤には、前記のベースポリマーおよび架橋剤のほか、必要に応じて、粘着剤の粘着力、凝集力、粘性、弾性率、ガラス転移温度などを調整するために、例えば、天然物や合成物である樹脂類、粘着性付与樹脂、酸化防止剤、紫外線吸収剤、染料、顔料、消泡剤、腐食抑制剤、光重合開始剤などの適宜な添加剤を配合することもできる。紫外線吸収剤には、サリチル酸エステル系化合物やベンゾフェノン系化合物、ベンゾトリアゾール系化合物、シアノアクリレート系化合物、ニッケル錯塩系化合物などがある。 In order to adjust the adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. of the adhesive, if necessary, in addition to the base polymer and the crosslinking agent, the high-elastic adhesive of the present invention includes, for example, Add appropriate additives such as natural and synthetic resins, tackifier resins, antioxidants, UV absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors, photoinitiators, etc. You can also. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.
　また、本発明で用いる高弾性粘着剤としては、光拡散剤を配合した光拡散性粘着剤を使用することができる。ここで用いる光拡散剤は、粘着剤層（第２の接着剤層）を構成するベースポリマーとは屈折率が異なる微粒子であればよく、無機化合物からなる微粒子や有機化合物（ポリマー）からなる微粒子を用いることができる。 In addition, as the high-elasticity adhesive used in the present invention, a light diffusable adhesive containing a light diffusing agent can be used. The light diffusing agent used here may be fine particles having a refractive index different from that of the base polymer constituting the pressure-sensitive adhesive layer (second adhesive layer), and may be fine particles made of an inorganic compound or fine particles made of an organic compound (polymer). Can be used.
　無機化合物からなる微粒子としては、例えば、酸化アルミニウム（屈折率１．７６）、酸化ケイ素（屈折率１．４５）などを挙げることができる。また、有機化合物（ポリマー）からなる微粒子としては、例えば、メラミンビーズ（屈折率１．５７）、ポリメタクリル酸メチルビーズ（屈折率１．４９）、メタクリル酸メチル／スチレン共重合体樹脂ビーズ（屈折率１．５０～１．５９）、ポリカーボネートビーズ（屈折率１．５５）、ポリエチレンビーズ（屈折率１．５３）、ポリスチレンビーズ（屈折率１．６）、ポリ塩化ビニルビーズ（屈折率１．４６）、シリコーン樹脂ビーズ（屈折率１．４６）などを挙げることができる。 Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Examples of the fine particles made of an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index). 1.50 to 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46) ), Silicone resin beads (refractive index 1.46), and the like.
　前記したようなアクリル系ベースポリマーを含めて、粘着剤層（第２の接着剤層）を構成するベースポリマーは、１．４前後の屈折率を示すことが多いので、そこに配合する光拡散剤は、その屈折率が１～２程度のものから、適宜選択すればよい。粘着剤層（第２の接着剤層）を構成するベースポリマーと光拡散剤との屈折率差は、通常０．０１以上であり、また画像表示装置の明るさと視認性の観点から、０．０１以上０．５以下とするのが好適である。 Since the base polymer constituting the pressure-sensitive adhesive layer (second adhesive layer) including the acrylic base polymer as described above often has a refractive index of around 1.4, the light diffusion to be mixed therewith The agent may be appropriately selected from those having a refractive index of about 1 to 2. The difference in refractive index between the base polymer constituting the pressure-sensitive adhesive layer (second adhesive layer) and the light diffusing agent is usually 0.01 or more. It is preferable to set it to 01 or more and 0.5 or less.
　光拡散剤として用いる微粒子は、球形のもの、それも単分散に近いものが好ましく、例えば、平均粒径が２～６μｍ程度の範囲にある微粒子が好適に用いられる。 The fine particles used as the light diffusing agent are preferably spherical and have a monodispersity. For example, fine particles having an average particle size in the range of about 2 to 6 μm are preferably used.
　光拡散剤の配合量は、それが配合された光拡散性粘着剤層に必要とされるヘイズ値や、それが適用される画像表示装置の明るさなどを考慮して、適宜決められるが、一般には、粘着剤層を構成するベースポリマー１００重量部に対して、３～３０重量部程度である。 The blending amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the light diffusing pressure-sensitive adhesive layer in which it is blended, the brightness of the image display device to which it is applied, Generally, the amount is about 3 to 30 parts by weight with respect to 100 parts by weight of the base polymer constituting the pressure-sensitive adhesive layer.
　また、光拡散剤が配合された光拡散性粘着剤層は、それを用いて得られる複合偏光板が適用された画像表示装置の明るさを確保するとともに、表示像のにじみやボケを生じにくくする観点から、そのヘイズが２０～８０％の範囲となるようにするのが好ましい。ヘイズは、JIS　K　7105に規定され、（拡散透過率／全光線透過率）×１００（％）で表される値である。 In addition, the light diffusing pressure-sensitive adhesive layer containing the light diffusing agent ensures the brightness of the image display device to which the composite polarizing plate obtained using the light diffusing agent is applied, and hardly causes bleeding or blurring of the display image. From this point of view, the haze is preferably in the range of 20 to 80%. The haze is a value defined by JIS K 7105 and expressed as (diffuse transmittance / total light transmittance) × 100 (%).
　さらに、光拡散剤が配合された光拡散性粘着剤層の厚みは、その接着力などに応じて決定されるが、通常は１～４０μｍの範囲である。光拡散性粘着剤層の厚みは３～２５μｍとするのが、良好な加工性を保ち、高い耐久性を示し、また画像表示装置を正面から見た場合や斜めから見た場合の明るさを保ち、表示像のにじみやボケが生じにくくする観点から、好適である。 Further, the thickness of the light diffusable pressure-sensitive adhesive layer in which the light diffusing agent is blended is determined according to the adhesive force and the like, but is usually in the range of 1 to 40 μm. The thickness of the light diffusive pressure-sensitive adhesive layer should be 3 to 25 μm to maintain good workability and high durability, and the brightness when the image display device is viewed from the front or obliquely. This is preferable from the viewpoint of keeping the display image from blurring and blurring.
　［第１の接着剤層］
　偏光フィルム１０と透明保護フィルム２０とは、第１の接着剤層４１を介して積層される。例えば、エポキシ系樹脂、ウレタン系樹脂、シアノアクリレート系樹脂、アクリルアミド系樹脂などを成分とする接着剤を用いて、第１の接着剤層４１を形成することができる。接着剤層を薄くする観点から好ましい接着剤として、水系の接着剤、すなわち、接着剤成分を水に溶解又は水に分散させたものを挙げることができる。水系の接着剤となりうる接着剤成分としては、例えば、水溶性の架橋性エポキシ樹脂、ウレタン系樹脂などを挙げることができる。また、別の好ましい接着剤として、無溶剤型の接着剤、具体的には、加熱や活性エネルギー線の照射によりモノマー又はオリゴマーを反応硬化させて接着剤層を形成するものを挙げることができる。 [First adhesive layer]
The polarizing film 10 and the transparent protective film 20 are laminated via the first adhesive layer 41. For example, the first adhesive layer 41 can be formed using an adhesive containing epoxy resin, urethane resin, cyanoacrylate resin, acrylamide resin, or the like as a component. A preferable adhesive from the viewpoint of reducing the thickness of the adhesive layer includes a water-based adhesive, that is, an adhesive component dissolved or dispersed in water. Examples of the adhesive component that can be a water-based adhesive include water-soluble crosslinkable epoxy resins and urethane resins. Another preferred adhesive is a solventless adhesive, specifically, an adhesive layer that is formed by reacting and curing a monomer or oligomer by heating or irradiation with an active energy ray.
　まず、水系の接着剤について説明する。水溶性の架橋性エポキシ樹脂としては、例えば、ジエチレントリアミンやトリエチレンテトラミンなどのポリアルキレンポリアミンと、アジピン酸等のジカルボン酸との反応で得られるポリアミドポリアミンに、エピクロロヒドリンを反応させて得られるポリアミドエポキシ樹脂を挙げることができる。このようなポリアミドエポキシ樹脂の市販品としては、住化ケムテックス株式会社から販売されている“スミレーズレジン650”や“スミレーズレジン675”などがある。 First, the water-based adhesive will be described. Examples of the water-soluble crosslinkable epoxy resin can be obtained by reacting epichlorohydrin with a polyamide polyamine obtained by a reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid. Mention may be made of polyamide epoxy resins. Examples of such commercially available polyamide epoxy resins include “Smiles Resin 650” and “Smiles Resin 675” sold by Sumika Chemtex Co., Ltd.
　接着剤成分として水溶性のエポキシ樹脂を用いる場合は、さらに塗工性と接着性を向上させるために、ポリビニルアルコール系樹脂などの他の水溶性樹脂を混合するのが好ましい。ポリビニルアルコール系樹脂は、部分ケン化ポリビニルアルコールや完全ケン化ポリビニルアルコールのほか、カルボキシル基変性ポリビニルアルコール、アセトアセチル基変性ポリビニルアルコール、メチロール基変性ポリビニルアルコール、アミノ基変性ポリビニルアルコール等の、変性されたポリビニルアルコール系樹脂であってもよい。中でも、酢酸ビニルと不飽和カルボン酸又はその塩との共重合体のケン化物、すなわち、カルボキシル基変性ポリビニルアルコールが好ましく用いられる。なお、ここでいう「カルボキシル基」とは、－ＣＯＯＨおよびその塩を含む概念である。 When a water-soluble epoxy resin is used as the adhesive component, it is preferable to mix other water-soluble resin such as polyvinyl alcohol resin in order to further improve the coatability and adhesiveness. Polyvinyl alcohol resin is modified such as partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol, etc. Polyvinyl alcohol resin may be used. Among them, a saponified product of a copolymer of vinyl acetate and unsaturated carboxylic acid or a salt thereof, that is, carboxyl group-modified polyvinyl alcohol is preferably used. Here, the “carboxyl group” is a concept including —COOH and a salt thereof.
　市販されている好適なカルボキシル基変性ポリビニルアルコールとしては、例えば、それぞれ株式会社クラレから販売されているクラレポバールKL-506、クラレポバールKL-318およびクラレポバールKL-118、それぞれ日本合成化学工業株式会社から販売されているゴーセナール（登録商標）T-330およびゴーセナール（登録商標）T-350、電気化学工業株式会社から販売されているDR-0415、それぞれ日本酢ビ・ポバール株式会社から販売されているAF-17、AT-17およびAP-17などが挙げられるが、これらに限定されるわけではなく、同様の性能を有するカルボキシル基変性ポリビニルアルコールであればよい。 Examples of suitable commercially available carboxyl group-modified polyvinyl alcohols include, for example, Kuraray Poval KL-506, Kuraray Poval KL-318 and Kura Lepoval KL-118 sold by Kuraray Co., Ltd. Gosenal (registered trademark) T-330 and Gosenal (registered trademark) T-350 sold by KK, DR-0415 sold by Denki Kagaku Kogyo Co., Ltd. Examples thereof include AF-17, AT-17, and AP-17, but are not limited thereto, and any carboxyl group-modified polyvinyl alcohol having the same performance may be used.
　水溶性の架橋性エポキシ樹脂を含む接着剤とする場合、そのエポキシ樹脂および必要に応じて加えられるポリビニルアルコール系樹脂などの他の水溶性樹脂を水に溶解して、接着剤溶液を構成する。この場合、水溶性の架橋性エポキシ樹脂は、水１００重量部あたり０．２～２重量部程度の範囲の濃度とするのが好ましい。また、ポリビニルアルコール系樹脂を配合する場合、その量は、好ましくは水１００重量部あたり１～１０重量部程度、さらに好ましくは１～５重量部程度である。 In the case of an adhesive containing a water-soluble crosslinkable epoxy resin, the epoxy resin and other water-soluble resin such as a polyvinyl alcohol resin added as necessary are dissolved in water to constitute an adhesive solution. In this case, the water-soluble crosslinkable epoxy resin preferably has a concentration in the range of about 0.2 to 2 parts by weight per 100 parts by weight of water. When the polyvinyl alcohol-based resin is blended, the amount is preferably about 1 to 10 parts by weight, more preferably about 1 to 5 parts by weight per 100 parts by weight of water.
　一方、水系の接着剤に好適に用いることができるウレタン系樹脂を含む水系の接着剤を用いる場合、適当なウレタン樹脂の例として、アイオノマー型のウレタン樹脂、特にポリエステル系アイオノマー型ウレタン樹脂を挙げることができる。ここで、アイオノマー型とは、骨格を構成するウレタン樹脂中に、少量のイオン性成分（親水成分）が導入されたものである。また、ポリエステル系アイオノマー型ウレタン樹脂とは、ポリエステル骨格を有するウレタン樹脂であって、その中に少量のイオン性成分（親水成分）が導入されたものである。このようなアイオノマー型ウレタン樹脂は、乳化剤を使用せずに直接、水中で乳化してエマルジョンとなるため、水系の接着剤として好適である。ポリエステル系アイオノマー型ウレタン樹脂の市販品として、例えば、ＤＩＣ株式会社から販売されている“ハイドラン（登録商標）AP-20”、“ハイドラン（登録商標）APX-101H”などがあり、いずれもエマルジョンの形で入手できる。 On the other hand, when using a water-based adhesive containing a urethane resin that can be suitably used for a water-based adhesive, examples of suitable urethane resins include ionomer-type urethane resins, particularly polyester-based ionomer-type urethane resins. Can do. Here, the ionomer type is obtained by introducing a small amount of an ionic component (hydrophilic component) into the urethane resin constituting the skeleton. The polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier and becomes an emulsion. Examples of commercially available polyester ionomer-type urethane resins include “Hydran (registered trademark) AP-20” and “Hydran (registered trademark) APX-101H” sold by DIC Corporation. Available in form.
　アイオノマー型のウレタン樹脂を接着剤成分とする場合、通常はさらにイソシアネート系などの架橋剤を配合するのが好ましい。イソシアネート系架橋剤は、分子内にイソシアナト基（－ＮＣＯ）を少なくとも２個有する化合物であり、その例は、２，４－トリレンジイソシアネート、フェニレンジイソシアネート、４，４′－ジフェニルメタンジイソシアネート、１，６－ヘキサメチレンジイソシアネート、イソホロンジイソシアネート等のポリイソシアネート単量体のほか、それらの複数分子がトリメチロールプロパン等の多価アルコールに付加したアダクト体、ジイソシアネート３分子がそれぞれの片末端イソシアナト基の部分でイソシアヌレート環を形成した３官能のイソシアヌレート体、ジイソシアネート３分子がそれぞれの片末端イソシアナト基の部分で水和・脱炭酸して形成されるビュレット体等のポリイソシアネート変性体などを含む。好適に使用しうる市販のイソシアネート系架橋剤として、例えば、大日本インキ化学工業株式会社から販売されている“ハイドラン（登録商標）アシスターC-1”などが挙げられる。 When an ionomer-type urethane resin is used as an adhesive component, it is usually preferable to add an isocyanate-based crosslinking agent. The isocyanate-based crosslinking agent is a compound having at least two isocyanato groups (—NCO) in the molecule. Examples thereof include 2,4-tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,6 -In addition to polyisocyanate monomers such as hexamethylene diisocyanate and isophorone diisocyanate, adducts in which a plurality of these molecules are added to polyhydric alcohols such as trimethylolpropane, and three molecules of diisocyanate are isocyanates at each isocyanato group. Examples include trifunctional isocyanurate having a nurate ring, and polyisocyanate-modified products such as a burette formed by hydration and decarboxylation of three diisocyanate molecules at each one-end isocyanato group. Examples of commercially available isocyanate-based crosslinking agents that can be suitably used include “Hydran (registered trademark) Assistor C-1” sold by Dainippon Ink and Chemicals, Inc.
　アイオノマー型のウレタン樹脂を含む水系接着剤を用いる場合は、粘度と接着性の観点から、そのウレタン樹脂の濃度が１０～７０重量％程度、さらには２０重量％以上、また５０重量％以下となるように、水中に分散させたものが好ましい。イソシアネート系架橋剤を配合する場合は、ウレタン樹脂１００重量部に対してイソシアネート系架橋剤が５～１００重量部程度となるように、その配合量を適宜選択すればよい。 When an aqueous adhesive containing an ionomer type urethane resin is used, the concentration of the urethane resin is about 10 to 70% by weight, further 20% by weight or more, and 50% by weight or less from the viewpoint of viscosity and adhesiveness. Thus, those dispersed in water are preferred. When the isocyanate crosslinking agent is blended, the blending amount may be appropriately selected so that the isocyanate crosslinking agent is about 5 to 100 parts by weight with respect to 100 parts by weight of the urethane resin.
　以上のような水系の接着剤は、偏光フィルム１０または透明保護フィルム２０の接着面に塗布されて第１の接着剤層４１とされ、両者が貼り合わされる。偏光フィルムと透明保護フィルムを貼合する方法は特に限定されるものではなく、例えば、偏光フィルム又は透明保護フィルムの表面に接着剤を均一に塗布し、塗布面にもう一方のフィルムを重ねてロール等により貼合し、乾燥する方法などが挙げられる。乾燥は、例えば、６０～１００℃程度の温度で行われる。乾燥後は、室温よりやや高い温度、例えば３０～５０℃程度の温度で１～１０日間程度養生することが、接着力を一層高めるうえで好ましい。 The water-based adhesive as described above is applied to the adhesive surface of the polarizing film 10 or the transparent protective film 20 to form the first adhesive layer 41, and the two are bonded together. The method for laminating the polarizing film and the transparent protective film is not particularly limited. For example, an adhesive is uniformly applied to the surface of the polarizing film or the transparent protective film, and the other film is overlapped on the coated surface and rolled. The method of pasting and drying by etc. is mentioned. Drying is performed at a temperature of about 60 to 100 ° C., for example. After drying, it is preferable to cure at a temperature slightly higher than room temperature, for example, at a temperature of about 30 to 50 ° C. for about 1 to 10 days, in order to further increase the adhesive strength.
　次に、無溶剤型の接着剤について説明する。無溶剤型の接着剤とは、実質的に溶剤を含まず、一般には、加熱や活性エネルギー線の照射により重合する硬化性の化合物と、重合開始剤とを含んで構成される。反応性の観点からは、カチオン重合で硬化するものが好ましく、特にエポキシ系の接着剤が好ましく用いられる。 Next, the solventless adhesive will be described. The solventless adhesive substantially does not contain a solvent, and generally includes a curable compound that is polymerized by heating or irradiation with active energy rays, and a polymerization initiator. From the viewpoint of reactivity, those that are cured by cationic polymerization are preferred, and epoxy adhesives are particularly preferred.
　この接着剤は、加熱又は活性エネルギー線の照射によるカチオン重合で硬化するものであることがより好ましい。特に、耐候性や屈折率などの観点から、分子内に芳香環を含まないエポキシ化合物が、硬化性化合物として好適に用いられる。分子内に芳香環を含まないエポキシ化合物を用いた接着剤は、例えば、特開２００４－２４５９２５号公報に記載されている。このような芳香環を含まないエポキシ化合物として、芳香族エポキシ化合物の水素化物、脂環式エポキシ化合物、脂肪族エポキシ化合物などが例示できる。接着剤に用いる硬化性のエポキシ化合物は、通常、分子中にエポキシ基を２個以上有している。 This adhesive is more preferably cured by cationic polymerization by heating or irradiation with active energy rays. In particular, from the viewpoint of weather resistance and refractive index, an epoxy compound that does not contain an aromatic ring in the molecule is suitably used as the curable compound. An adhesive using an epoxy compound that does not contain an aromatic ring in the molecule is described in, for example, JP-A-2004-245925. Examples of such epoxy compounds that do not contain an aromatic ring include hydrides of aromatic epoxy compounds, alicyclic epoxy compounds, aliphatic epoxy compounds, and the like. The curable epoxy compound used for the adhesive usually has two or more epoxy groups in the molecule.
　芳香族エポキシ化合物の水素化物について説明すると、これは、芳香族エポキシ化合物を触媒の存在下、加圧下で芳香環に選択的に水素化反応を行うことにより得られ得る。芳香族エポキシ化合物しては、例えば、ビスフェノールＡのジグリシジルエーテル、ビスフェールＦのジグリシジルエーテル、ビスフェノールＳのジグリシジルエーテル等のビスフェノール型エポキシ化合物；フェノールノボラックエポキシ樹脂、クレゾールノボラックエポキシ樹脂、ヒドロキシベンズアルデヒドフェノールノボラックエポキシ樹脂等のノボラック型のエポキシ樹脂；テトラヒドロキシジフェニルメタンのグリシジルエーテル、テトラヒドロキシベンゾフェノンのグリシジルエーテル、エポキシ化ポリビニルフェノール等の多官能型のエポキシ化合物などが挙げられる。これら芳香族エポキシ化合物の水素化物の中でも好ましいものとして、水素化されたビスフェノールＡのジグリシジルエーテルが挙げられる。 Describing the hydride of an aromatic epoxy compound, this can be obtained by selectively hydrogenating an aromatic epoxy compound to an aromatic ring under pressure in the presence of a catalyst. Examples of the aromatic epoxy compound include bisphenol-type epoxy compounds such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether; phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde Examples thereof include novolak-type epoxy resins such as phenol novolac epoxy resins; polyfunctional epoxy compounds such as glycidyl ether of tetrahydroxydiphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinylphenol. Among these hydrides of aromatic epoxy compounds, hydrogenated bisphenol A diglycidyl ether is preferred.
　次に脂環式エポキシ化合物について説明すると、これは、次式に示す如き、脂環式環に結合したエポキシ基を分子内に少なくとも１個有する化合物である。 Next, the alicyclic epoxy compound will be described. This is a compound having at least one epoxy group bonded to the alicyclic ring in the molecule, as shown in the following formula.
Figure JPOXMLDOC01-appb-C000012
Figure JPOXMLDOC01-appb-C000012
式中、ｍは２～５の整数を表す。
　この式における(ＣＨ2)m中の水素原子を１個又は複数個取り除いた構造を有する基が他の化学構造を有する基に結合した化合物が、脂環式エポキシ化合物となりうる。また、脂環式環を形成する水素がメチル基やエチル基のような直鎖状アルキル基で適宜置換されていてもよい。中でも、エポキシシクロペンタン環（上式においてｍ＝３のもの）や、エポキシシクロヘキサン環（上式においてｍ＝４のもの）を有する化合物を用いることが好ましい。脂環式エポキシ化合物の具体例として、次のようなものを挙げることができる。 In the formula, m represents an integer of 2 to 5.
A compound in which a group having a structure in which one or more hydrogen atoms in (CH 2 ) m in this formula are removed is bonded to a group having another chemical structure can be an alicyclic epoxy compound. Further, the hydrogen forming the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among them, it is preferable to use a compound having an epoxycyclopentane ring (m = 3 in the above formula) or an epoxycyclohexane ring (m = 4 in the above formula). Specific examples of the alicyclic epoxy compound include the following.
　３，４－エポキシシクロヘキシルメチル　３，４－エポキシシクロヘキサンカルボキシレート、
　３，４－エポキシ－６－メチルシクロヘキシルメチル　３，４－エポキシ－６－メチルシクロヘキサンカルボキシレート、
　エチレンビス（３，４－エポキシシクロヘキサンカルボキシレート）、
　ビス（３，４－エポキシシクロヘキシルメチル）　アジペート、
　ビス（３，４－エポキシ－６－メチルシクロヘキシルメチル）　アジペート、
　ジエチレングリコールビス（３，４－エポキシシクロヘキシルメチルエーテル）、
　エチレングリコールビス（３，４－エポキシシクロヘキシルメチルエーテル）、
　２，３，１４，１５－ジエポキシ－７，１１，１８，２１－テトラオキサトリスピロ－［５．２．２．５．２．２］ヘンイコサン（また、３，４－エポキシシクロヘキサンスピロ－２'，６'－ジオキサンスピロ－３''，５''－ジオキサンスピロ－３'''，４'''－エポキシシクロヘキサンとも命名できる化合物）、
　４－（３，４－エポキシシクロヘキシル）－２，６－ジオキサ－８，９－エポキシスピロ［５．５］ウンデカン、
　４－ビニルシクロヘキセンジオキサイド、　ビス－２，３－エポキシシクロペンチルエーテル、
　ジシクロペンタジエンジオキサイドなど。 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
Ethylene bis (3,4-epoxycyclohexanecarboxylate),
Bis (3,4-epoxycyclohexylmethyl) adipate,
Bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,
Diethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
Ethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro- [5.2.2.5.2.2] henicosane (also 3,4-epoxycyclohexanespiro-2 ′ , 6′-Dioxanespiro-3 ″, 5 ″ -Dioxanespiro-3 ′ ″, 4 ′ ″-epoxycyclohexane compound)
4- (3,4-epoxycyclohexyl) -2,6-dioxa-8,9-epoxyspiro [5.5] undecane,
4-vinylcyclohexene dioxide, bis-2,3-epoxycyclopentyl ether,
Dicyclopentadiene dioxide etc.
　次に脂肪族エポキシ化合物について説明すると、脂肪族多価アルコール又はそのアルキレンオキサイド付加物のポリグリシジルエーテルが、これに該当する。その例としては、１，４－ブタンジオールのジグリシジルエーテル、１，６－ヘキサンジオールのジグリシジルエーテル、グリセリンのトリグリシジルエーテル、トリメチロールプロパンのトリグリシジルエーテル、ポリエチレングリコールのジグリシジルエーテル、ポリプロピレングリコールのジグリシジルエーテル、エチレングリコールやポリプロピレングリコール、グリセリンのような脂肪族多価アルコールに１種又は２種以上のアルキレンオキサイド（エチレンオキサイドやポリプロピレンオキサイド）を付加することにより得られるポリエーテルポリオールのポリグリシジルエーテルなどが挙げられる。 Next, the aliphatic epoxy compound will be described. The polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof corresponds to this. Examples include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol Polyglycidyl of a polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or polypropylene oxide) to an aliphatic polyhydric alcohol such as diglycidyl ether, ethylene glycol, polypropylene glycol or glycerin Examples include ether.
　ここに例示したエポキシ化合物のそれぞれは単独で使用してもよいし、別の１種以上と混合して使用してもよい。 Each of the epoxy compounds exemplified here may be used alone or in combination with one or more other types.
　無溶剤型の接着剤に使用するエポキシ化合物のエポキシ当量は、通常３０～３,０００ｇ／当量、好ましくは５０～１,５００ｇ／当量の範囲である。エポキシ当量が３０ｇ／当量を下回ると、硬化後の保護フィルムの可撓性が低下したり、接着強度が低下したりする可能性がある。一方、３,０００ｇ／当量を超えると、他の成分との相溶性が低下する可能性がある。 The epoxy equivalent of the epoxy compound used for the solventless adhesive is usually in the range of 30 to 3,000 g / equivalent, preferably 50 to 1,500 g / equivalent. If the epoxy equivalent is less than 30 g / equivalent, there is a possibility that the flexibility of the cured protective film is lowered or the adhesive strength is lowered. On the other hand, if it exceeds 3,000 g / equivalent, the compatibility with other components may decrease.
　エポキシ化合物をカチオン重合で硬化させるためには、カチオン重合開始剤が配合される。カチオン重合開始剤は、可視光線、紫外線、Ｘ線、電子線等の活性エネルギー線の照射、又は加熱により、カチオン種又はルイス酸を発生し、エポキシ基の重合反応開始に寄与する。いずれのタイプのカチオン重合開始剤であっても、潜在性が付与されていることが、作業性の観点から好ましい。 In order to cure the epoxy compound by cationic polymerization, a cationic polymerization initiator is blended. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, or heating, and contributes to the initiation of the polymerization reaction of the epoxy group. Regardless of the type of cationic polymerization initiator, it is preferable from the viewpoint of workability that latency is imparted.
　以下、光カチオン重合開始剤について説明する。光カチオン重合開始剤を使用すると、常温での硬化が可能となり、偏光フィルムの耐熱性あるいは膨張による歪を考慮する必要が減少し、位相差フィルムと偏光フィルムとを良好に接着することができる。また、光カチオン重合開始剤は光で触媒的に作用するため、エポキシ化合物に混合しても保存安定性や作業性に優れる。活性エネルギー線の照射によりカチオン種やルイス酸を生じる化合物として、例えば、芳香族ジアゾニウム塩、芳香族ヨードニウム塩や芳香族スルホニウム塩等のオニウム塩、鉄－アレン錯体などを挙げることができる。これらの中でも、特に芳香族スルホニウム塩は、３００ｎｍ以上の波長領域でも紫外線吸収特性を有することから、硬化性に優れ、良好な機械強度や接着強度を有する硬化物を与えることができるため、好ましく用いられる。 Hereinafter, the photocationic polymerization initiator will be described. When a photocationic polymerization initiator is used, curing at room temperature becomes possible, the need to consider the heat resistance of the polarizing film or distortion due to expansion is reduced, and the retardation film and the polarizing film can be favorably bonded. Moreover, since a photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy compound. Examples of compounds that generate cation species and Lewis acids upon irradiation with active energy rays include onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes. Among these, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.
　これらの光カチオン重合開始剤は市販品として容易に入手でき、例えば、それぞれ商品名で、“カヤラッド　PCI-220”、“カヤラッド　PCI-620”（以上、日本化薬（株）製）、“UVI-6990”（ユニオンカーバイド社製）、“アデカオプトマー　SP-150”、“アデカオプトマー　SP-170”（以上、（株）ＡＤＥＫＡ製）、“CI-5102”、“CIT-1370”、“CIT-1682”、“CIP-1866S”、“CIP-2048S”、“CIP-2064S”（以上、日本曹達（株）製）、“DPI-101”、“DPI-102”、“DPI-103”、“DPI-105”、“MPI-103”、“MPI-105”、“BBI-101”、“BBI-102”、“BBI-103”、“BBI-105”、“TPS-101”、“TPS-102”、“TPS-103”、“TPS-105”、“MDS-103”、“MDS-105”、“DTS-102”、“DTS-103”（以上、みどり化学（株）製）、“PI-2074”（ローディア社製）などが挙げられる。特に、日本曹達（株）製の“CI-5102”は、好ましい開始剤の一つである。 These photocationic polymerization initiators can be easily obtained as commercial products. For example, “Kayarad PCI-220”, “Kayarad PCI-620” (manufactured by Nippon Kayaku Co., Ltd.), “UVI” -6990 "(manufactured by Union Carbide)," Adekaoptomer SP-150 "," Adekaoptomer SP-170 "(above, manufactured by ADEKA Corporation)," CI-5102 "," CIT-1370 "," "CIT-1682", "CIP-1866S", "CIP-2048S", "CIP-2064S" (above, manufactured by Nippon Soda Co., Ltd.), "DPI-101", "DPI-102", "DPI-103" , “DPI-105”, “MPI-103”, “MPI-105”, “BBI-101”, “BBI-102”, “BBI-103”, “BBI-105”, “TPS-101”, “ "TPS-102", "TPS-103", "TPS-105", "MDS-103", "MDS-105", "DTS-102", "DTS-103" (Midori Chemical Co., Ltd.) "PI-2074" (manufactured by Rhodia). In particular, “CI-5102” manufactured by Nippon Soda Co., Ltd. is one of the preferred initiators.
　光カチオン重合開始剤の配合量は、エポキシ化合物１００重量部に対して、通常０.５～２０重量部であり、好ましくは１重量部以上、また好ましくは１５重量部以下である。 The amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less with respect to 100 parts by weight of the epoxy compound.
　さらに、必要に応じて光増感剤を併用することができる。光増感剤を使用することで、反応性が向上し、硬化物の機械強度や接着強度を向上させることができる。光増感剤としては例えば、カルボニル化合物、有機硫黄化合物、過硫化物、レドックス系化合物、アゾ及びジアゾ化合物、ハロゲン化合物、光還元性色素などが挙げられる。光増感剤を配合する場合、その量は、光カチオン重合性エポキシ樹脂組成物の１００重量部に対して、通常０.１～２０重量部程度である。 Furthermore, a photosensitizer can be used together if necessary. By using a photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. When the photosensitizer is blended, the amount is usually about 0.1 to 20 parts by weight with respect to 100 parts by weight of the photocationically polymerizable epoxy resin composition.
　次に、熱カチオン重合開始剤について説明する。加熱によりカチオン種又はルイス酸を発生する化合物として、ベンジルスルホニウム塩、チオフェニウム塩、チオラニウム塩、ベンジルアンモニウム、ピリジニウム塩、ヒドラジニウム塩、カルボン酸エステル、スルホン酸エステル、アミンイミドなどを挙げることができる。これらの熱カチオン重合開始剤も、市販品として容易に入手することができ、例えば、いずれも商品名で、“アデカオプトン　CP77”及び“アデカオプトン　CP66”（以上、（株）ＡＤＥＫＡ製）、“CI-2639”及び“CI-2624”（以上、日本曹達（株）製）、“サンエイド　SI-60L”、“サンエイド　SI-80L”及び“サンエイド　SI-100L”（以上、三新化学工業（株）製）などが挙げられる。 Next, the thermal cationic polymerization initiator will be described. Examples of the compound that generates a cationic species or a Lewis acid by heating include benzylsulfonium salt, thiophenium salt, thiolanium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide. These thermal cationic polymerization initiators can also be easily obtained as commercial products. For example, “ADEKA OPTON CP77” and “ADEKA OPTON CP66” (above, manufactured by ADEKA Corporation), “CI- "2639" and "CI-2624" (Nippon Soda Co., Ltd.), "San-Aid SI-60L", "Sun-Aid SI-80L" and "Sun-Aid SI-100L" (Sanshin Chemical Industry Co., Ltd.) ) And the like.
　以上説明した光カチオン重合と熱カチオン重合を併用することも、有用な技術である。
　エポキシ系接着剤は、さらにオキセタン類やポリオール類など、カチオン重合を促進する化合物を含有してもよい。 It is also a useful technique to combine the photocationic polymerization and the thermal cationic polymerization described above.
The epoxy adhesive may further contain a compound that promotes cationic polymerization, such as oxetanes and polyols.
　以上のような無溶剤型の接着剤を用いる場合も、その接着剤を、透明保護フィルム、または偏光フィルムの接着面に塗布し、両者を貼り合わせて、複合偏光板とすることができる。無溶剤型接着剤を透明保護フィルム、または偏光フィルムに塗工する方法に特別な限定はなく、例えば、ドクターブレード、ワイヤーバー、ダイコーター、カンマコーター、グラビアコーターなど、種々の塗工方式が利用できる。また、各塗工方式には各々最適な粘度範囲があるため、少量の溶剤を用いて粘度調整を行ってもよい。このために用いる溶剤は、偏光フィルムの光学性能を低下させずに、エポキシ系接着剤を良好に溶解するものであればよく、例えば、トルエンに代表される炭化水素類、酢酸エチルに代表されるエステル類などの有機溶剤が使用できる。無溶剤型のエポキシ系接着剤を用いる場合、第１の接着剤層の厚さは通常５０μｍ以下、好ましくは２０μｍ以下、さらに好ましくは１０μｍ以下であり、また通常は１μｍ以上である。 Even when the above solventless type adhesive is used, the adhesive can be applied to the adhesive surface of the transparent protective film or the polarizing film and bonded together to form a composite polarizing plate. There is no particular limitation on the method of applying the solventless adhesive to the transparent protective film or polarizing film. For example, various coating methods such as doctor blade, wire bar, die coater, comma coater, gravure coater are used. it can. Moreover, since each coating method has an optimum viscosity range, the viscosity may be adjusted using a small amount of solvent. The solvent used for this is not particularly limited as long as it can dissolve the epoxy-based adhesive satisfactorily without degrading the optical performance of the polarizing film. For example, hydrocarbons typified by toluene, typified by ethyl acetate, and the like. Organic solvents such as esters can be used. When a solventless type epoxy adhesive is used, the thickness of the first adhesive layer is usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less, and usually 1 μm or more.
　以上のような、無溶剤の接着剤は、偏光フィルム１０または透明保護フィルム２０の接着面に塗布されて第１の接着剤層４１とされ、両者が貼り合わされる。偏光フィルムに透明保護フィルムを貼合した後は、活性エネルギー線を照射するか、又は加熱することにより、エポキシ系接着剤層を硬化させ、透明保護フィルムを偏光フィルム上に固着させる。活性エネルギー線の照射により硬化させる場合、好ましくは紫外線が用いられる。具体的な紫外線光源としては、低圧水銀灯、中圧水銀灯、高圧水銀灯、ブラックライトランプ、メタルハライドランプなどを挙げることができる。活性エネルギー線、例えば紫外線の照射強度や照射量は、重合開始剤を十分に活性化させ、かつ硬化後の接着剤層や偏光フィルム、透明保護フィルムに悪影響を与えないように、適宜設定することができる。また加熱により硬化させる場合は、一般的に知られた方法で加熱することができ、そのときの温度や時間も、重合開始剤を十分に活性化させ、かつ硬化後の接着剤層や偏光フィルム、透明保護フィルムに悪影響を与えないように、適宜設定することができる。 The solventless adhesive as described above is applied to the adhesive surface of the polarizing film 10 or the transparent protective film 20 to form the first adhesive layer 41, and the two are bonded together. After bonding a transparent protective film to a polarizing film, an active energy ray is irradiated or it heats, an epoxy-type adhesive bond layer is hardened, and a transparent protective film is fixed on a polarizing film. In the case of curing by irradiation with active energy rays, ultraviolet rays are preferably used. Specific examples of the ultraviolet light source include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a black light lamp, and a metal halide lamp. Active energy rays such as ultraviolet irradiation intensity and irradiation dose should be set appropriately so that the polymerization initiator is fully activated and the adhesive layer, polarizing film and transparent protective film after curing are not adversely affected. Can do. Further, when cured by heating, it can be heated by a generally known method, and the temperature and time at that time sufficiently activate the polymerization initiator, and the cured adhesive layer or polarizing film It can be set appropriately so as not to adversely affect the transparent protective film.
　[複合偏光板の製造方法]
　通常の複合偏光板の製法としては、まず、上記の第一の接着剤層を介して、透明保護フィルムと偏光フィルムとの貼合が行なわれる。 [Production method of composite polarizing plate]
As a manufacturing method of a normal composite polarizing plate, first, the transparent protective film and the polarizing film are bonded through the first adhesive layer.
　この第一の接着剤層を介して片面に透明保護フィルムが貼合された偏光フィルムは、一旦、巻き取り装置によって塩化ビニル管などのコアに巻き取られる。片面に保護フィルムを貼合しておくことにより、フィルムを巻き取っても、偏光フィルムが裂けるなどの問題はなくなる。巻き取りに先立って、透明保護フィルムが貼合された偏光フィルムの片面または両面に、さらに再剥離可能なプロテクトフィルムを貼合してもよい。コアに巻き取られ、片面に保護フィルムが貼合された偏光フィルムは、次に偏光フィルムの透明保護フィルムの貼合されていない面が位相差フィルムに貼合される。この面に前記の再剥離可能なプロテクトフィルムを貼合している場合は、位相差フィルムの貼合前に、このプロテクトフィルムが剥離される。 The polarizing film having a transparent protective film bonded on one side through the first adhesive layer is once wound around a core such as a vinyl chloride tube by a winding device. By sticking a protective film on one side, there is no problem of tearing the polarizing film even if the film is wound. Prior to winding, a re-peelable protective film may be further bonded to one or both sides of the polarizing film to which the transparent protective film is bonded. In the polarizing film wound around the core and having the protective film bonded to one surface, the surface of the polarizing film where the transparent protective film is not bonded is bonded to the retardation film. When the removable protective film is bonded to this surface, the protective film is peeled before the retardation film is bonded.
　偏光フィルムと位相差フィルムとを貼合する方法は特に限定されないが、通常は、まず偏光フィルムまたは位相差フィルムの表面に第２の接着剤層が形成される。この第２の接着剤層は、偏光フィルムまたは位相差フィルムに前記のような硬化性のエポキシ系樹脂組成物を用いる方法や、ベースポリマーを主体とする粘着剤溶液を塗布し乾燥する方法によって形成できるほか、離型処理が施された支持フィルム（セパレータ）の離型処理面に第２の接着剤層が形成されたもの（セパレータ付き粘着剤）を用意し、それを第２の接着剤層側で偏光フィルムまたは位相差フィルムの表面に貼り合わせる方法によっても形成できる。 Although the method for bonding the polarizing film and the retardation film is not particularly limited, usually, the second adhesive layer is first formed on the surface of the polarizing film or the retardation film. This second adhesive layer is formed by a method using a curable epoxy resin composition as described above for a polarizing film or a retardation film, or a method of applying and drying a pressure-sensitive adhesive solution mainly composed of a base polymer. In addition, a support film (separator) that has been subjected to a release treatment is provided with a second adhesive layer formed on the release treatment surface (adhesive with separator), and this is used as the second adhesive layer. It can also be formed by a method of adhering to the surface of the polarizing film or retardation film on the side.
　例えば、トルエンや酢酸エチルなどの有機溶媒に第２の接着剤層を形成するための組成物を溶解又は分散させて、その濃度が１０～４０重量％の溶液を調製し、これを偏光フィルムまたは位相差フィルムの表面に直接塗布して乾燥させて第２の接着剤層を形成する方法が挙げられる。このようにして形成された第２の接着剤層は、シリコーン系等の離型剤による処理が施された樹脂フィルムからなるセパレータを積層しておくことにより、偏光フィルムと位相差フィルムを貼合するまでの間、保存しておくことができる。また、別の方法としては、先に前記のセパレータ上に第２の接着剤層を形成しておいた後、偏光フィルム又は位相差フィルムに転写する方法などを採用することができる。 For example, a composition for forming the second adhesive layer is dissolved or dispersed in an organic solvent such as toluene or ethyl acetate to prepare a solution having a concentration of 10 to 40% by weight. There is a method in which the second adhesive layer is formed by directly applying to the surface of the retardation film and drying it. The second adhesive layer formed in this way is bonded to a polarizing film and a retardation film by laminating a separator made of a resin film that has been treated with a silicone-based release agent. You can save it until you do. Moreover, as another method, after forming the 2nd adhesive bond layer on the said separator previously, the method of transcribe | transferring to a polarizing film or retardation film etc. are employable.
　さらに、第２の接着剤層を偏光フィルムまたは位相差フィルムの表面に形成する際に、必要に応じて、偏光フィルムまたは位相差フィルムの第２の接着剤層形成面に密着性を向上させるための処理、例えばコロナ処理などを施してもよく、同様の処理を偏光フィルムまたは位相差フィルムに貼り合わされる第２の接着剤層の表面に施してもよい。 Further, when forming the second adhesive layer on the surface of the polarizing film or retardation film, if necessary, to improve the adhesion to the second adhesive layer forming surface of the polarizing film or retardation film. For example, a corona treatment or the like may be performed, and the same treatment may be performed on the surface of the second adhesive layer bonded to the polarizing film or the retardation film.
　偏光フィルムと位相差フィルムとの貼合は、従来から知られている技術により行なわれ、例えば、貼合ロール等を用いて偏光フィルムの偏光透過軸に対して位相差フィルムの遅相軸が直交又は平行となるように積層する方法や、偏光フィルムの偏光透過軸に対して位相差フィルムの遅相軸が所定の角度となるように貼合する方法により行なわれる。 The polarizing film and the retardation film are bonded by a conventionally known technique. For example, the slow axis of the retardation film is orthogonal to the polarizing transmission axis of the polarizing film using a bonding roll or the like. Or it is performed by the method of laminating | stacking so that it may become parallel, and the method of bonding so that the slow axis of a phase difference film may become a predetermined angle with respect to the polarization transmission axis of a polarizing film.
　以上のように構成される本発明の複合偏光板は、その位相差フィルムの外側に、さらに第２の粘着剤を配置して、液晶セルへの貼り合わせが可能となるようにすることができる。このような複合偏光板を、液晶セルの少なくとも一方の側に貼合して、液晶表示装置が構成される。液晶セルの両面に本発明の複合偏光板を配置することもできるし、片面に本発明の複合偏光板を配置し、他面には別の偏光板を配置することもできる。複合偏光板は、液晶セルへの貼合にあたっては、通常、その位相差フィルム側が液晶セルに向き合うように配置される。 The composite polarizing plate of the present invention configured as described above can be bonded to a liquid crystal cell by further disposing a second adhesive on the outside of the retardation film. . Such a composite polarizing plate is bonded to at least one side of the liquid crystal cell to constitute a liquid crystal display device. The composite polarizing plate of the present invention can be disposed on both sides of the liquid crystal cell, the composite polarizing plate of the present invention can be disposed on one side, and another polarizing plate can be disposed on the other side. The composite polarizing plate is usually arranged so that the retardation film side faces the liquid crystal cell when bonding to the liquid crystal cell.
　第２の粘着剤層を形成する粘着剤については、貯蔵粘弾性率は特に限定されずに種々公知の粘着剤（感圧性接着剤）を用いることができ、上述したような高弾性粘着剤を用いることもできる。 For the pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer, the storage viscoelastic modulus is not particularly limited, and various known pressure-sensitive adhesives (pressure sensitive adhesives) can be used. It can also be used.
　［液晶表示装置］
　図２には、液晶セルの両面に本発明の複合偏光板を配置する例を示した。図２の（Ａ）はその断面模式図であり、図２の（Ｂ）は軸角度の関係を説明するための斜視図である。この例でも、各層を離間した状態で示しているが、実際には隣り合う各層が密着していることになる。図２に示す例では、液晶セル６０の下側に、位相差フィルム３０／偏光フィルム１０／透明保護フィルム２０からなる複合偏光板を、その位相差フィルム３０側が液晶セル６０に向き合うように積層し、液晶セル６０の上側にも、位相差フィルム３０／偏光フィルム１０／透明保護フィルム２０からなる複合偏光板を、その位相差フィルム３０側が液晶セル６０に向き合うように積層している。それぞれの複合偏光板において、位相差フィルム３０の遅相軸３５と偏光フィルム１０の吸収軸１５が平行関係になっており、下側の偏光フィルム１０は、その吸収軸１５が液晶セル６０の長辺方向６５に直交し、上側の偏光フィルム１０は、その吸収軸１５が液晶セル６０の長辺方向６５に平行になっている。いずれかの透明保護フィルム２０の外側にバックライトが配置され、液晶表示装置となる。液晶セルが横電界モードである場合に、この構成は特に有効である。 [Liquid Crystal Display]
In FIG. 2, the example which arrange | positions the composite polarizing plate of this invention on both surfaces of a liquid crystal cell was shown. FIG. 2A is a schematic cross-sectional view thereof, and FIG. 2B is a perspective view for explaining the relationship of shaft angles. Also in this example, each layer is shown in a separated state, but in actuality, adjacent layers are in close contact with each other. In the example shown in FIG. 2, a composite polarizing plate composed of a retardation film 30 / polarizing film 10 / transparent protective film 20 is laminated below the liquid crystal cell 60 so that the retardation film 30 side faces the liquid crystal cell 60. The composite polarizing plate composed of the retardation film 30 / polarizing film 10 / transparent protective film 20 is also laminated on the upper side of the liquid crystal cell 60 so that the retardation film 30 side faces the liquid crystal cell 60. In each composite polarizing plate, the slow axis 35 of the retardation film 30 and the absorption axis 15 of the polarizing film 10 are in a parallel relationship, and the lower polarizing film 10 has an absorption axis 15 that is the length of the liquid crystal cell 60. The absorption axis 15 of the upper polarizing film 10 that is orthogonal to the side direction 65 is parallel to the long side direction 65 of the liquid crystal cell 60. A backlight is disposed outside one of the transparent protective films 20 to form a liquid crystal display device. This configuration is particularly effective when the liquid crystal cell is in a transverse electric field mode.
　以下、実施例を示して本発明をさらに具体的に説明するが、本発明はこれらの例によって限定されるものではない。例中、使用量または含有量を表す部および％は、特記ないかぎり重量基準である。 Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, parts and% representing the amount used or content are based on weight unless otherwise specified.
　［実施例１］
　（ａ）硬化性エポキシ系樹脂組成物からなる接着剤Ａ１の調製
　脂環式エポキシ系樹脂である上記式（ＩＩＩ）に相当するジカルボン酸のエポキシシクロヘキシルメチルエステル類としてビス（３，４－エポキシシクロヘキシルメチル）アジペート１００部、水素化エポキシ系樹脂として水添ビスフェノールＡのジグリシジルエーテル２５部、および、光カチオン重合開始剤として４，４’－ビス（ジフェニルスルホニオ）ジフェニルスルフィド　ビス（ヘキサフルオロホスフェート）２．２部を混合した後、脱泡して、硬化性エポキシ系樹脂組成物からなる接着剤Ａを得た。なお、光カチオン重合開始剤は、５０質量％プロピレンカーボネート溶液として配合した。 [Example 1]
(A) Preparation of Adhesive A1 Comprising Curable Epoxy Resin Composition Bis (3,4-epoxycyclohexyl) as an epoxycyclohexylmethyl ester of dicarboxylic acid corresponding to the above formula (III) which is an alicyclic epoxy resin 100 parts of methyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A as a hydrogenated epoxy resin, and 4,4′-bis (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate) as a photocationic polymerization initiator After 2.2 parts were mixed, defoaming was performed to obtain an adhesive A made of a curable epoxy resin composition. The photocationic polymerization initiator was blended as a 50% by mass propylene carbonate solution.
　（ｂ）片面透明保護フィルム付き偏光フィルムの作製
　平均重合度約２,４００、ケン化度９９．９モル％以上であるポリビニルアルコールか
らなる厚さ７５μｍのポリビニルアルコールフィルムを、乾式で約５倍に一軸延伸し、さらに緊張状態を保ったまま、６０℃の純水に１分間浸漬した後、ヨウ素／ヨウ化カリウム／水の重量比が０．０５／５／１００の水溶液に２８℃で６０秒間浸漬した。その後、ヨウ化カリウム／ホウ酸／水の重量比が８．５／８．５／１００の水溶液に７２℃で３００秒間浸漬した。引き続き、２６℃の純水で２０秒間洗浄した後、６５℃で乾燥して、ポリビニルアルコール樹脂フィルムにヨウ素が吸着配向された偏光フィルムを得た。 (B) Production of polarizing film with single-sided transparent protective film 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 saponification degree of 99.9 mol% or more is about 5 times as dry. The film was uniaxially stretched and immersed in pure water at 60 ° C. for 1 minute while maintaining the tension state, and then in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Soaked. 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, the film 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 the polyvinyl alcohol resin film.
　この偏光フィルムの片面に、表面にケン化処理を施した厚み４０μｍのトリアセチルセルロースフィルムを、５重量部％ポリビニルアルコール水溶液を接着剤として貼合し、乾燥させて溶媒を除去し、片面保護フィルム付き偏光フィルムとした。 On one side of this polarizing film, a 40 μm thick triacetylcellulose film having a saponified surface is bonded as an adhesive with a 5% by weight polyvinyl alcohol aqueous solution, dried to remove the solvent, and a single side protective film A polarizing film was attached.
　（ｃ）位相差フィルムの貼合
　スチレン－無水マレイン酸系共重合樹脂（ノヴァケミカル社製の「ダイラーク（登録商標）　D332」（Ｔｇ＝１３１℃））をコア層とし、平均粒径２００μｍのアクリル系ゴム粒子が約２０％配合されているメタクリル系樹脂（住友化学（株）製の「テクノロイ（登録商標）　S001」に使用されている樹脂（Ｔｇ＝１０５℃））をスキン層として、３層共押出を行い、コア層の厚みが６０μｍで、その両面に各々厚みが７２μｍのスキン層が形成された樹脂３層フィルムを得た。この樹脂３層フィルムを１４２℃で２倍に延伸して、総厚みが１０４μｍ、面内レターデーションが１４０ｎｍ、Ｎｚ係数が０.０である負の位相差フィルムを得た。この位相差フィルムにおける各層の膜厚は、コア層が約３０μｍ、各々のスキン層が約３７μｍであった。 (C) Lamination of retardation film A styrene-maleic anhydride copolymer resin ("Dylark (registered trademark) D332" (Tg = 131 ° C) manufactured by Nova Chemical Co., Ltd.) is used as a core layer, and an acrylic having an average particle diameter of 200 µm. Three layers of a methacrylic resin (resin used in “Technoloy (registered trademark) S001” manufactured by Sumitomo Chemical Co., Ltd. (Tg = 105 ° C.)) in which about 20% of rubber particles are blended. Co-extrusion was performed to obtain a resin three-layer film having a core layer thickness of 60 μm and skin layers each having a thickness of 72 μm formed on both surfaces thereof. This resin three-layer film was stretched twice at 142 ° C. to obtain a negative retardation film having a total thickness of 104 μm, an in-plane retardation of 140 nm, and an Nz coefficient of 0.0. The thickness of each layer in the retardation film was about 30 μm for the core layer and about 37 μm for each skin layer.
　こうして得られた位相差フィルムを、照射量１６．８ｋＪ/ｍ2でコロナ処理を施した後、上記透明保護フィルム付き偏光フィルムの偏光フィルム面上に、上記接着剤Ａを用いて貼合した後、ベルトコンベア付き紫外線照射装置（ランプ：Ｆｕｓｉｏｎ　Ｄランプ、積算光量１０００ｍＪ／ｃｍ2）にて紫外線の照射を行ない、室温で１時間放置して、複合偏光板を得た。こうして得られた複合偏光板のフィルムに浮きやはがれ、気泡などはなく外観は良好なものであった。 The retardation film thus obtained is subjected to corona treatment at an irradiation dose of 16.8 kJ / m 2 and then bonded onto the polarizing film surface of the polarizing film with a transparent protective film using the adhesive A. Then, ultraviolet irradiation was performed with an ultraviolet irradiation device with a belt conveyor (lamp: Fusion D lamp, integrated light quantity 1000 mJ / cm 2 ), and left at room temperature for 1 hour to obtain a composite polarizing plate. The composite polarizing plate film thus obtained had good appearance with no floating or peeling, no bubbles and the like.
　得られた複合偏光板の偏光フィルムと位相差フィルムとの間の接着力を、ＪＩＳ　Ｋ　６８５４－１：１９９９に規定される９０度剥離試験により評価した。９０度剥離試験において、剥離速度は２００ｍｍ／分とし、試験片として、複合偏光板を幅２５ｍｍ×長さ１２０ｍｍの大きさに切り出したものを用いた。この試験片をシート状粘着剤（リンテック（株）製の「Ｐ－３１３２」（商品名））を用いてソーダガラスに固定し、（株）島津製作所製のオートグラフ「ＡＧ－１」を用いて、位相差フィルムと偏光フィルムとの間で剥がすようにして試験を行なった。その結果、１．７Ｎ／２５ｍｍという高い９０度剥離強度が得られた。 The adhesive force between the polarizing film and the retardation film of the obtained composite polarizing plate was evaluated by a 90-degree peel test specified in JIS K 6854-1: 1999. In the 90-degree peel test, the peel rate was 200 mm / min, and a composite polarizing plate cut into a size of 25 mm wide × 120 mm long was used as a test piece. This test piece was fixed to soda glass using a sheet-like adhesive (“P-3132” (trade name) manufactured by Lintec Corporation), and Autograph “AG-1” manufactured by Shimadzu Corporation was used. Then, the test was performed by peeling between the retardation film and the polarizing film. As a result, a 90 degree peel strength as high as 1.7 N / 25 mm was obtained.
　［比較例１］
　上記接着剤Ａ１の代わりに、水１００重量部に対してカルボキシ基変性ポリビニルアルコール（株式会社クラレ製「クラレポバール　KL318」）３重量部および水溶性ポリアミドエポキシ樹脂（住化煙テック株式会社製「スミレーズ（登録商標）レジン　650」）１．５重量部を含む水溶液からなる水系接着剤を用いたこと以外は、実施例１と同様の方法で、偏光フィルム上に位相差フィルムを接着し、複合偏光板を作製した。得られた複合偏光板は、作製直後ですら位相差フィルムと偏光フィルムとの間に剥離が生じており、９０度剥離試験用のサンプルを作製することができないほど、接着力が弱かった。 [Comparative Example 1]
Instead of the adhesive A1, 3 parts by weight of carboxy group-modified polyvinyl alcohol (“Kuraray Poval KL318” manufactured by Kuraray Co., Ltd.) and water-soluble polyamide epoxy resin (“Smiles” manufactured by Sumika Smoke Tech Co., Ltd.) per 100 parts by weight of water (Registered trademark Resin 650)) A retardation film was adhered on a polarizing film in the same manner as in Example 1 except that an aqueous adhesive comprising an aqueous solution containing 1.5 parts by weight was used. A plate was made. The obtained composite polarizing plate had peeling between the retardation film and the polarizing film even immediately after production, and the adhesive strength was so weak that a sample for a 90-degree peeling test could not be produced.
　以下の例において、貯蔵弾性率は次の方法によって測定した。
　［貯蔵弾性率の測定方法］
　以下の実施例および比較例において、粘着剤の貯蔵弾性率（Ｇ′）は、測定対象の粘着剤からなる直径８ｍｍ×厚み１ｍｍの円柱状の試験片を作製し、動的粘弾性測定装置（Dynamic　Analyzer　RDA　II：Reometric社製）を用いて、周波数１Ｈｚの捻りせん断法で初期歪み１Ｎとし、温度２３℃または８０℃の条件で測定を行なった。 In the following examples, the storage elastic modulus was measured by the following method.
[Method for measuring storage modulus]
In the following Examples and Comparative Examples, the storage elastic modulus (G ′) of the adhesive is a dynamic viscoelasticity measuring device (8 mm in diameter × 1 mm in thickness) made of a pressure-sensitive adhesive to be measured. Using Dynamic Analyzer RDA II (manufactured by Reometric), the initial strain was set to 1N by the torsional shearing method with a frequency of 1 Hz, and the measurement was performed at a temperature of 23 ° C. or 80 ° C.
　また、以下の実施例および比較例においては、粘着剤として、次のものを用いた。
　（粘着剤Ａ２：高弾性粘着剤）
　粘着剤Ａ２は、アクリル酸ブチルとアクリル酸の共重合体にウレタンアクリレートオリゴマーが配合され、さらにイソシアネート系架橋剤が添加された粘着剤である。粘着剤Ａの貯蔵弾性率を上記の方法で測定したところ、２３℃において０．４０ＭＰａ、８０℃において０．１８ＭＰａであった。 In the following Examples and Comparative Examples, the following were used as pressure-sensitive adhesives.
(Adhesive A2: High elastic adhesive)
The pressure-sensitive adhesive A2 is a pressure-sensitive adhesive in which a urethane acrylate oligomer is blended with a copolymer of butyl acrylate and acrylic acid, and an isocyanate crosslinking agent is further added. When the storage elastic modulus of the pressure-sensitive adhesive A was measured by the above method, it was 0.40 MPa at 23 ° C. and 0.18 MPa at 80 ° C.
　以下の実施例において、粘着剤Ａ２は、上記組成の有機溶剤溶液を、離型処理が施された厚さ３８μｍのポリエチレンテレフタレートフィルム（セパレータ）の離型処理面に塗工し、乾燥し、さらに紫外線照射することにより、このセパレータの表面に厚さ１５μｍの粘着剤Ａの層が形成されたセパレータ付き粘着剤として調製した。 In the following examples, the adhesive A2 was applied to the release treatment surface of a 38 μm thick polyethylene terephthalate film (separator) having been subjected to the release treatment, dried, It was prepared as a pressure-sensitive adhesive with a separator in which a layer of pressure-sensitive adhesive A having a thickness of 15 μm was formed on the surface of the separator by irradiation with ultraviolet rays.
　（粘着剤Ｂ：低弾性粘着剤）
　粘着剤Ｂは、市販のアクリル系シート状粘着剤であり、ウレタンアクリレートオリゴマーは配合されていない。粘着剤Ｂの貯蔵弾性率を上記の方法で測定したところ、２３℃において０．０５ＭＰａ、８０℃において０．０４ＭＰａであった。 (Adhesive B: Low elasticity adhesive)
The adhesive B is a commercially available acrylic sheet-like adhesive, and no urethane acrylate oligomer is blended therein. When the storage elastic modulus of the adhesive B was measured by the above method, it was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C.
　以下の実施例および比較例においては、粘着剤Ｂとして、離型処理が施された厚さ３８μｍのポリエチレンテレフタレートフィルム（セパレータ）の離型処理面に厚さ１５μｍの粘着剤Ｂの層が設けられている市販のセパレータ付き粘着剤を使用した。 In the following examples and comparative examples, the adhesive B is provided with a layer of the adhesive B having a thickness of 15 μm on the release treatment surface of the 38 μm-thick polyethylene terephthalate film (separator) subjected to the release treatment. A commercially available pressure-sensitive adhesive with a separator was used.
　（粘着剤Ｃ：低弾性粘着剤）
　粘着剤Ｃは、市販のアクリル系シート状粘着剤であり、ウレタンアクリレートオリゴマーは配合されていない。粘着剤Ｃの貯蔵弾性率を上記の方法で測定したところ、２３℃において０．１０ＭＰａ、８０℃において０．０４ＭＰａであった。 (Adhesive C: Low elasticity adhesive)
The adhesive C is a commercially available acrylic sheet-like adhesive, and no urethane acrylate oligomer is blended therein. When the storage elastic modulus of the adhesive C was measured by the above method, it was 0.10 MPa at 23 ° C. and 0.04 MPa at 80 ° C.
　以下の比較例においては、粘着剤Ｃとして、離型処理が施された厚さ３８μｍのポリエチレンテレフタレートフィルム（セパレータ）の離型処理面に厚さ１５μｍの粘着剤Ｃの層が設けられている市販のセパレータ付き粘着剤を使用した。 In the following comparative examples, as the adhesive C, a commercial product in which a layer of the adhesive C having a thickness of 15 μm is provided on the release treatment surface of the polyethylene terephthalate film (separator) having a thickness of 38 μm subjected to the release treatment. An adhesive with a separator was used.
　［実施例２］
　（ａ）片面透明保護フィルム付き偏光フィルムの作製
　平均重合度約２，４００、ケン化度９９．９モル％以上で厚さ７５μｍのポリビニルアルコールフィルムを、乾式で約５倍に一軸延伸し、さらに緊張状態を保ったまま、６０℃の純水に１分間浸漬した後、ヨウ素／ヨウ化カリウム／水の重量比が０．０５／５／１００の水溶液に２８℃で６０秒間浸漬した。その後、ヨウ化カリウム／ホウ酸／水の重量比が８．５／８．５／１００の水溶液に７２℃で３００秒間浸漬した。引き続き２６℃の純水で２０秒間洗浄した後、６５℃で乾燥して、ポリビニルアルコールにヨウ素が吸着配向された偏光フィルムを得た。 [Example 2]
(A) Production of polarizing film with single-sided transparent protective film Polyvinyl alcohol film having an average degree of polymerization of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm 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.
　この偏光フィルムの片面に、表面にケン化処理を施した厚み４０μｍのトリアセチルセルロースフィルム（透明保護フィルム）を、５重量％ポリビニルアルコール水溶液を接着剤として貼合し、乾燥させて溶媒を除去し、片面に透明保護フィルムが貼合された偏光フィルムを得た。 On one side of this polarizing film, a 40 μm thick triacetyl cellulose film (transparent protective film) having a saponified surface was bonded as an adhesive with a 5% by weight polyvinyl alcohol aqueous solution and dried to remove the solvent. A polarizing film having a transparent protective film bonded on one side was obtained.
　（ｂ）位相差フィルムの貼合
　スチレン－無水マレイン酸系共重合樹脂〔ノヴァケミカル社製の“ダイラーク（登録商標）D332”（Ｔｇ＝１３１℃）〕をコア層とし、平均粒径２００ｎｍのアクリル系ゴム粒子が約２０％配合されているメタクリル系樹脂〔住友化学株式会社製の“テクノロイ（登録商標）S001”に使用されている樹脂（Ｔｇ＝１０５℃）〕をスキン層として、３層共押出を行い、コア層の厚みが６０μｍで、その両面に各々厚みが７２μｍのスキン層が形成された樹脂３層フィルムを得た。この樹脂３層フィルムを１４２℃で２倍に延伸して、総厚みが１０４μｍ、面内レターデーションが１４０ｎｍ、Ｎｚ係数が０．０である負の位相差フィルムを得た。この位相差フィルムにおける各層の膜厚は、コア層が約３０μｍ、各々のスキン層が約３７μｍであった。 (B) Lamination of retardation film A styrene-maleic anhydride copolymer resin ("Dylark (registered trademark) D332" (Tg = 131 ° C) manufactured by Nova Chemical Co., Ltd.) is used as a core layer, and an acrylic having an average particle diameter of 200 nm. A methacrylic resin (resin used in “Technoloy (registered trademark) S001” manufactured by Sumitomo Chemical Co., Ltd. (Tg = 105 ° C.)) in which about 20% of rubber particles are blended is used as a skin layer. Extrusion was performed to obtain a resin three-layer film having a core layer thickness of 60 μm and skin layers each having a thickness of 72 μm formed on both surfaces thereof. This resin three-layer film was stretched twice at 142 ° C. to obtain a negative retardation film having a total thickness of 104 μm, an in-plane retardation of 140 nm, and an Nz coefficient of 0.0. The thickness of each layer in the retardation film was about 30 μm for the core layer and about 37 μm for each skin layer.
　こうして得られた位相差フィルムに照射量１６．８ｋＪ／ｍ2でコロナ処理を施した。その後、そのコロナ処理面と、上記（ａ）で作製した片面に透明保護フィルムが貼合された偏光フィルムの透明保護フィルムとは反対の面（偏光フィルム面）とを、粘着剤Ａからなるシートを用いて貼合し、本発明の複合偏光板を得た。こうして得られた複合偏光板の外観は良好なものであった。 The retardation film thus obtained was subjected to corona treatment at an irradiation dose of 16.8 kJ / m 2 . Then, the sheet | seat which consists of adhesive A with the surface (polarizing film surface) opposite to the transparent protective film of the polarizing film by which the corona treatment surface and the transparent protective film bonded by the one side produced by said (a) were carried out. Was used to obtain a composite polarizing plate of the present invention. The appearance of the composite polarizing plate thus obtained was good.
　実施例１で得られた複合偏光板の位相差フィルム面を粘着剤Ｂでソーダガラス（液晶セルの代わりとして使用）に固定し、５０℃で２０分間のオートクレーブ処理を施して複合偏光板をガラス板に密着させた。この状態で、－４０℃の雰囲気に３０分置き、次に＋８０℃の雰囲気に移して３０分置くことを１サイクルとし、これを５０サイクル繰り返すヒートショック試験を行った。実施例１の複合偏光板は、試験後にも欠陥は観察されず、良好な状態を維持していた。 The retardation film surface of the composite polarizing plate obtained in Example 1 was fixed to soda glass (used as a substitute for a liquid crystal cell) with adhesive B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. It was made to adhere to a board. In this state, a heat shock test was performed by placing in an atmosphere of −40 ° C. for 30 minutes, then moving to an atmosphere of + 80 ° C. and placing for 30 minutes as one cycle, and repeating this for 50 cycles. The composite polarizing plate of Example 1 maintained a good state with no defects observed after the test.
　［実施例３］
　（ａ）片面透明保護フィルム付き偏光フィルムの作製
　ビス（３，４－エポキシシクロヘキシルメチル）アジペート１００部、水添ビスフェノールＡのジグリシジルエーテル２５部、および光カチオン重合開始剤として４，４'－ビス（ジフェニルスルホニオ）ジフェニルスルフィド　ビス（ヘキサフルオロホスフェート）２．２部を混合した後、脱泡して、硬化性エポキシ樹脂組成物からなる接着剤Ａを得た。なお、光カチオン重合開始剤は、５０％プロピレンカーボネート溶液として配合した。 [Example 3]
(A) Production of polarizing film with single-sided transparent protective film 100 parts of bis (3,4-epoxycyclohexylmethyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A, and 4,4′-bis as a photocationic polymerization initiator After mixing 2.2 parts of (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate), defoaming was performed to obtain an adhesive A made of a curable epoxy resin composition. The cationic photopolymerization initiator was blended as a 50% propylene carbonate solution.
　実施例２の（ａ）に示した方法と同様にして作製した偏光フィルムの片面に、表面にケン化処理を施した厚み４０μｍのトリアセチルセルロースフィルム（透明保護フィルム）を、上記硬化性エポキシ樹脂組成物からなる接着剤を用いて貼合した後、ベルトコンベア付き紫外線照射装置（ランプ：Ｆｕｓｉｏｎ　Ｄランプ、積算光量１０００ｍＪ／ｃｍ2）にて紫外線の照射を行い、室温で１時間放置して、片面に透明保護フィルムを有する偏光フィルムとした。 On one side of a polarizing film produced in the same manner as in the method shown in (a) of Example 2, a 40 μm thick triacetyl cellulose film (transparent protective film) having a surface subjected to saponification treatment was applied to the curable epoxy resin. After pasting using an adhesive composed of the composition, ultraviolet irradiation is performed with an ultraviolet irradiation device with a belt conveyor (lamp: Fusion D lamp, integrated light quantity 1000 mJ / cm 2 ), and left at room temperature for 1 hour. It was set as the polarizing film which has a transparent protective film on one side.
　（ｂ）位相差フィルムの貼合
　実施例２の（ｂ）に示した方法と同様にして作製し、コロナ処理を施した位相差フィルムに、上記（ａ）で作製した透明保護フィルム付き偏光フィルムの偏光フィルム面（透明保護フィルムとは反対の面）とを、粘着剤Ａからなるシートを用いて貼合し、本発明の複合偏光板を得た。こうして得られた複合偏光板の外観は、フィルムの浮きやはがれ、気泡などがなく、良好なものであった。 (B) Lamination of retardation film Polarizing film with transparent protective film produced in the above (a) on a retardation film produced in the same manner as in Example 2 (b) and subjected to corona treatment The polarizing film surface (surface opposite to the transparent protective film) was bonded using a sheet made of the adhesive A to obtain the composite polarizing plate of the present invention. The appearance of the composite polarizing plate thus obtained was good with no film floating or peeling and no bubbles.
　［比較例２］
　偏光フィルムと位相差フィルムとを貼合する粘着剤を、粘着剤Ｂに変更し、その他は実施例２と同様にして複合偏光板を得た。こうして得られた偏光板の外観は良好なものであった。 [Comparative Example 2]
The adhesive which bonds a polarizing film and retardation film was changed into the adhesive B, and others were carried out similarly to Example 2, and obtained the composite polarizing plate. The appearance of the polarizing plate thus obtained was good.
　比較例２で得られた複合偏光板の位相差フィルム面を粘着剤Ｂでソーダガラス（液晶セルの代わりとして使用）に固定し、５０℃で２０分間のオートクレーブ処理を施して複合偏光板をガラス板に密着させた。この状態で、－４０℃の雰囲気に３０分置き、次に＋８０℃の雰囲気に移して３０分置くことを１サイクルとし、これを５０サイクル繰り返すヒートショック試験を行った。比較例２の複合偏光板は、試験後に位相差フィルムとガラスの間の粘着剤層に気泡が発生し、実用に足るものではなかった。 The retardation film surface of the composite polarizing plate obtained in Comparative Example 2 is fixed to soda glass (used as an alternative to a liquid crystal cell) with adhesive B, and subjected to autoclaving at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. It was made to adhere to a board. In this state, a heat shock test was performed by placing in an atmosphere of −40 ° C. for 30 minutes, then moving to an atmosphere of + 80 ° C. and placing for 30 minutes as one cycle, and repeating this for 50 cycles. In the composite polarizing plate of Comparative Example 2, bubbles were generated in the pressure-sensitive adhesive layer between the retardation film and the glass after the test, which was not practical.
　［比較例３］
　偏光フィルムと位相差フィルムとを貼合する粘着剤を、粘着剤Ｃに変更し、その他は実施例２と同様にして複合偏光板を得た。こうして得られた偏光板の外観は良好なものであった。 [Comparative Example 3]
The adhesive which bonds a polarizing film and retardation film was changed into the adhesive C, and the others were carried out similarly to Example 2, and obtained the composite polarizing plate. The appearance of the polarizing plate thus obtained was good.
　比較例３で得られた複合偏光板の位相差フィルム面を粘着剤Ｂでソーダガラス（液晶セルの代わりとして使用）に固定し、５０℃で２０分間のオートクレーブ処理を施して複合偏光板をガラス板に密着させた。この状態で、－４０℃の雰囲気に３０分置き、次に＋８０℃の雰囲気に移して３０分置くことを１サイクルとし、これを５０サイクル繰り返すヒートショック試験を行った。比較例３の複合偏光板は、試験後に位相差フィルムとガラスの間の粘着剤層に気泡が発生し、実用に足るものではなかった。 The retardation film surface of the composite polarizing plate obtained in Comparative Example 3 is fixed to soda glass (used as a substitute for a liquid crystal cell) with adhesive B, and subjected to an autoclave treatment at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. It was made to adhere to a board. In this state, a heat shock test was performed by placing in an atmosphere of −40 ° C. for 30 minutes, then moving to an atmosphere of + 80 ° C. and placing for 30 minutes as one cycle, and repeating this for 50 cycles. In the composite polarizing plate of Comparative Example 3, bubbles were generated in the pressure-sensitive adhesive layer between the retardation film and the glass after the test, which was not practical.
　今回開示された実施の形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
　本発明の複合偏光板は、種々の液晶表示装置における光学部材として広く利用され得るものであり、例えば、テレビ等の大型液晶表示装置や、コンピュータ用ディスプレイ、カーナビ、携帯電話、携帯端末機器等に用いられる中小型液晶表示装置における光学部材として利用され得るものである。 The composite polarizing plate of the present invention can be widely used as an optical member in various liquid crystal display devices. For example, it can be used in large liquid crystal display devices such as televisions, computer displays, car navigation systems, mobile phones, and mobile terminal devices. It can be used as an optical member in the medium- and small-sized liquid crystal display device used.

Claims (13)

  1. 　偏光フィルム（１０）の一方の面に第１の接着剤層（４１）を介して透明保護フィルム（２０）が貼合され、偏光フィルム（１０）の他方の面に第２の接着剤層（４２）を介して位相差フィルム（３０）が貼合されてなる複合偏光板であって、
    　該位相差フィルム（３０）がスチレン系樹脂からなるコア層（３１）の両面に、ゴム粒子を含有する（メタ）アクリル系樹脂組成物からなるスキン層（３２）が形成された３層構造からなり、
    　前記第２の接着剤層（４２）が活性化エネルギー線の照射または加熱により硬化するエポキシ系樹脂を含有するエポキシ系樹脂組成物の硬化物層からなる複合偏光板。     The transparent protective film (20) is bonded to one surface of the polarizing film (10) via the first adhesive layer (41), and the second adhesive layer ( 42) is a composite polarizing plate in which the retardation film (30) is bonded via
    The retardation film (30) has a three-layer structure in which a skin layer (32) made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer (31) made of a styrene resin. Become
    The composite polarizing plate which consists of a hardened | cured material layer of the epoxy resin composition containing the epoxy resin which the said 2nd adhesive bond layer (42) hardens | cures by irradiation of an activation energy ray or a heating.
  2. 　前記エポキシ系樹脂が分子内に芳香環を含まないエポキシ系樹脂である、請求の範囲１記載の複合偏光板。 The composite polarizing plate according to claim 1, wherein the epoxy resin is an epoxy resin containing no aromatic ring in the molecule.
  3. 　前記エポキシ系樹脂が水素化エポキシ系樹脂、脂環式エポキシ系樹脂または脂肪族エポキシ系樹脂である、請求の範囲１記載の複合偏光板。 The composite polarizing plate according to claim 1, wherein the epoxy resin is a hydrogenated epoxy resin, an alicyclic epoxy resin, or an aliphatic epoxy resin.
  4. 　前記エポキシ系樹脂組成物が溶剤成分を実質的に含まない無溶剤型の組成物である、請求の範囲１記載の複合偏光板。 2. The composite polarizing plate according to claim 1, wherein the epoxy resin composition is a solvent-free composition substantially free of a solvent component.
  5. 　位相差フィルム（３０）のコア層（３１）の膜厚が１０～１００μｍであり、スキン層（３２）の膜厚が、１０～１００μｍである、請求の範囲１記載の複合偏光板。 The composite polarizing plate according to claim 1, wherein the thickness of the core layer (31) of the retardation film (30) is 10 to 100 µm, and the thickness of the skin layer (32) is 10 to 100 µm.
  6. 　位相差フィルム（３０）のコア層（３１）のガラス転位温度が１２０℃以上であり、スキン層（３２）のガラス転位温度が１２０℃以下である、請求の範囲１記載の複合偏光板。 The composite polarizing plate according to claim 1, wherein the glass transition temperature of the core layer (31) of the retardation film (30) is 120 ° C or higher and the glass transition temperature of the skin layer (32) is 120 ° C or lower.
  7. 　液晶セルの少なくとも一方の面に、請求の範囲１記載の複合偏光板が配置されている液晶表示装置。 A liquid crystal display device in which the composite polarizing plate according to claim 1 is disposed on at least one surface of the liquid crystal cell.
  8. 　偏光フィルム（１０）の一方の面に第１の接着剤層（４１）を介して透明保護フィルム（２０）が貼合され、偏光フィルム（１０）の他方の面に第２の接着剤層（４２）を介して位相差フィルム（３０）が貼合されてなる複合偏光板であって、
    　該位相差フィルム（３０）がスチレン系樹脂からなるコア層（３１）の両面に、ゴム粒子を含有する（メタ）アクリル系樹脂組成物からなるスキン層（３２）が形成された３層構造からなり、
    　前記第２の接着剤層（４２）が８０℃の温度において０．１ＭＰａ以上の貯蔵弾性率を示す高弾性粘着剤から形成されている複合偏光板。     The transparent protective film (20) is bonded to one surface of the polarizing film (10) via the first adhesive layer (41), and the second adhesive layer ( 42) is a composite polarizing plate in which the retardation film (30) is bonded via
    The retardation film (30) has a three-layer structure in which a skin layer (32) made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer (31) made of a styrene resin. Become
    The composite polarizing plate in which the second adhesive layer (42) is formed of a high elastic pressure-sensitive adhesive having a storage elastic modulus of 0.1 MPa or more at a temperature of 80 ° C.
  9. 　前記位相差フィルム（３０）のコア層（３１）の膜厚が１０～１００μｍであり、スキン層（３２）の膜厚が、１０～１００μｍである、請求の範囲８記載の複合偏光板。 The composite polarizing plate according to claim 8, wherein the thickness of the core layer (31) of the retardation film (30) is 10 to 100 µm, and the thickness of the skin layer (32) is 10 to 100 µm.
  10. 　前記位相差フィルム（３０）のコア層（３１）のガラス転移温度が１２０℃以上であり、スキン層（３２）のガラス転移温度が１２０℃以下である、請求の範囲８記載の複合偏光板。 The composite polarizing plate according to claim 8, wherein the glass transition temperature of the core layer (31) of the retardation film (30) is 120 ° C or higher and the glass transition temperature of the skin layer (32) is 120 ° C or lower.
  11. 　前記第２の接着剤層（４２）の厚みが１～４０μｍである、請求の範囲８記載の複合偏光板。 The composite polarizing plate according to claim 8, wherein the thickness of the second adhesive layer (42) is 1 to 40 µm.
  12. 　一軸延伸され、ヨウ素又は二色性染料が吸着配向されたポリビニルアルコール系樹脂フィルムからなる偏光フィルム（１０）の一方の面に透明保護フィルム（２０）を貼合して巻き取り、
    　その後にもう一方の面に、スチレン系樹脂からなるコア層（３１）と、コア層（３１）の両面にゴム粒子が配合された（メタ）アクリル系樹脂組成物からなるスキン層（３２）を有する２種３層構造よりなる位相差フィルム（３０）を、８０℃の温度範囲において０．１ＭＰａ以上の貯蔵弾性率を示す高弾性粘着剤によって貼合することを含む、請求の範囲８記載の複合偏光板の製造方法。     A transparent protective film (20) is bonded and wound on one surface of a polarizing film (10) made of a polyvinyl alcohol-based resin film that is uniaxially stretched and adsorbed and oriented with iodine or a dichroic dye,
    Thereafter, on the other side, a core layer (31) made of styrene resin and a skin layer (32) made of (meth) acrylic resin composition in which rubber particles are blended on both sides of the core layer (31). The retardation film (30) having a two-kind three-layer structure having a high elastic pressure-sensitive adhesive having a storage elastic modulus of 0.1 MPa or more in a temperature range of 80 ° C. is included. A method for producing a composite polarizing plate.
  13. 　液晶セルの少なくとも一方の面に、請求の範囲８記載の複合偏光板が配置されている液晶表示装置。 A liquid crystal display device in which the composite polarizing plate according to claim 8 is disposed on at least one surface of the liquid crystal cell.
PCT/JP2009/055415 2008-03-26 2009-03-19 Composite polarizing plate, method for producing composite polarizing plate, and liquid crystal display device using the same WO2009119435A1 (en)

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CN101813798A (en) * 2009-02-23 2010-08-25 住友化学株式会社 Composite polarizing plate and the IPS mode LCD that uses it
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