JP2010139729A - Method for manufacturing composite polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a composite polarizing plate with good productivity, the composite polarizing plate being formed by laminating a polarizing plate and a retardation film using a styrene resin film having a width smaller than the polarizing plate, and has excellent adhesion strength between a polarizing film and the retardation film. <P>SOLUTION: The method for manufacturing the composite polarizing plate includes steps of: manufacturing a polarizing plate with a releasable film and with a single-side transparent protective film; cutting the polarizing plate along a longitudinal direction according to the width of a retardation film; removing the releasable film from the polarizing film; laminating a pressure-sensitive adhesive layer showing a storage modulus of not less than 0.1 MPa at 80°C on one surface of the retardation film or on the polarizing film surface of the polarizing plate; and bonding the retardation film to the polarizing plate across the pressure-sensitive adhesive layer. The retardation film comprises an oriented film having a three-layer structure composed of a core layer made of a styrene resin and a skin layer made of an (meth)acrylic resin composition containing rubber particles, layered on either face of the core layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a composite polarizing plate.

  Liquid crystal display devices are used in various display devices by taking advantage of low power consumption, operation at low voltage, light weight and thinness. This liquid crystal display device is composed of many optical members such as a liquid crystal cell, a polarizing plate, a retardation film, a light collecting sheet, a diffusion film, a light guide plate, and a light reflecting sheet. Therefore, by improving the number of films or sheets constituting these optical members and reducing the film thickness, it is possible to improve the production efficiency and brightness of the liquid crystal display device and to reduce the weight and thickness. Such research is actively conducted.

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

  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 the thickness thereof is usually about 30 to 120 μm. In addition, an adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin is often used for laminating the protective film.

  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 using 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 deteriorated or the protective film and the polarizing film are easily peeled off.

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

On the other hand, the 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 ) Defined by the Nz coefficient is 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.

  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), for example, norbornene or maleic anhydride. However, such copolymerization cannot sufficiently improve the mechanical strength and chemical resistance.

  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) include an acyclic olefin monomer and a cyclic olefin monomer in an aromatic vinyl monomer typified by styrene. It is described that a copolymerized terpolymer is used as a retardation film. Furthermore, in JP-A-2003-90912 (Patent Document 6), an orientation film made of a norbornene-based resin and an orientation film made of a styrene-maleic anhydride copolymer resin are laminated via an adhesive layer, 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), a first layer made of a styrene resin and a second layer made of an acrylic resin composition in which rubber particles are blended are provided as an adhesive layer. It is described that the film is laminated without using a film to form a retardation film.

  However, when a styrene resin film is applied to a retardation film, in order to achieve desired retardation characteristics and mechanical strength, the width of the styrene resin film cannot be widened. However, the conventional method for producing a polarizing plate with a retardation film has a problem that the productivity is remarkably reduced. That is, in this case, when a polarizing plate and a retardation film having a smaller width than the polarizing plate are bonded together, a polarizing plate portion where the retardation film is not bonded is generated. On the other hand, in order to cut the polarizing plate into a predetermined shape to be bonded to the liquid crystal cell, it is usually cut at a right angle or an oblique angle with respect to the longitudinal direction, and then cut again into the predetermined shape. The polarizing plate part where the film is not bonded is discarded. Furthermore, productivity is significantly reduced by adding a polarizing plate portion to which the retardation film is not bonded to the cutting length.

Furthermore, when the retardation film to which the styrene resin film is applied is used so as to also serve as a protective film for the polarizing film, the adhesiveness with the polarizing film may be inferior.
JP-A-8-43812 Japanese Patent Laid-Open No. 9-325216 Japanese translation of PCT publication No. 2002-517583 JP 2003-50316 A JP 2003-207640 A JP 2003-90912 A JP 2004-167823 A JP 2006-192637 A

  An object of the present invention is to apply a polarizing plate and a styrene-based resin film, which is formed by laminating a retardation film having a smaller width than the polarizing plate, and having excellent adhesion between the polarizing film and the retardation film. It is in providing the method of manufacturing with good productivity.

The present invention is a stretched film having a three-layer structure of a core layer made of a styrene resin and a skin layer made of a (meth) acrylic resin composition containing rubber particles, which is laminated on both surfaces of the core layer. It is related with the method of manufacturing the composite polarizing plate provided with the retardation film which consists of, and the polarizing plate with a single-sided transparent protective film which has a transparent protective film on the single side | surface of a polarizing film laminated | stacked on this retardation film. The method for producing the composite polarizing plate of the present invention comprises:
(A) a step of pasting a transparent protective film on one side of the polarizing film, pasting a peelable film having adhesiveness on the opposite side, and producing a polarizing plate with a single-sided transparent protective film;
(B) cutting the polarizing plate with a single-sided transparent protective film along the longitudinal direction according to the width of the retardation film;
(C) removing the peelable film from the polarizing film surface;
(D) A pressure-sensitive adhesive layer having a storage elastic modulus of 0.1 MPa or more at 80 ° C. is laminated on one surface of the retardation film or the polarizing film surface of the polarizing plate with the single-side transparent protective film that has undergone the above-described step (C). Process,
(E) a step of bonding a retardation film to the polarizing film surface of the polarizing plate with a single-sided transparent protective film from which the peelable film has been removed, via the pressure-sensitive adhesive layer;
It is characterized by including.

  In one preferred embodiment, the method for producing a composite polarizing plate of the present invention includes the step (A), the step (B), the step (C), the step (D), and the step (E) in this order. In D), an adhesive layer is laminated | stacked on the polarizing film surface of the polarizing plate with a single-sided transparent protective film which passed through the process (C).

  In another preferred embodiment, the method for producing a composite polarizing plate of the present invention includes the above-described step (A), step (C), step (D), step (B) and step (E) in this order, In the step (D), the pressure-sensitive adhesive layer is laminated on the polarizing film surface of the polarizing plate with a single-side transparent protective film that has undergone the step (C).

  In still another preferred embodiment, the method for producing a composite polarizing plate of the present invention includes the step (A), the step (B), the step (C) and the step (E) in this order, and in the step (D), The pressure-sensitive adhesive layer is laminated on one side of the retardation film.

  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.

  The glass transition temperature of the core layer of the retardation film is preferably 120 ° C. or higher, and the glass transition temperature of the skin layer is preferably 120 ° C. or lower.

  The width of the retardation film is preferably 10% or more smaller than the width of the polarizing plate with a single-sided transparent protective film produced in the step (A).

  In the said process (A), a polarizing film and a transparent protective film can be bonded together using the adhesive agent containing a polyvinyl alcohol-type resin and an epoxy resin. Or you may bond using the adhesive agent which consists of a resin composition containing the epoxy resin hardened | cured by irradiation of an active energy ray or a heating. In this case, the epoxy resin preferably contains a compound having one or more epoxy groups bonded to the alicyclic ring in the molecule.

  The thickness of the transparent protective film is preferably 20 to 300 μm. Moreover, it is preferable that the thickness of an adhesive layer is 1-40 micrometers.

  According to the method for producing a composite polarizing plate of the present invention, a polarizing plate with a single-sided transparent protective film is cut along the longitudinal direction according to the width of the retardation film before being bonded to the retardation film, and the retardation film And the polarizing plate with a single-sided transparent protective film to be bonded and the polarizing film with a single-sided transparent protective film that is not bonded to the polarizing film are not reduced. Furthermore, since the part which does not bond with the phase difference film of the polarizing plate with a single-sided transparent protective film can be used for another product, the whole productivity improves remarkably.

  Moreover, the composite polarizing plate obtained by this invention is excellent also in the adhesiveness of a phase difference film and a polarizing film, and has high durability performance.

  Furthermore, by sticking a peelable film having adhesiveness to the polarizing film side of the polarizing plate with a single-sided transparent protective film to be cut, bonding of the transparent protective film and the polarizing film, or of the polarizing film in cutting Damage can be prevented.

  The composite polarizing plate obtained by the present invention can be suitably applied to a liquid crystal display device, particularly a liquid crystal display device including a transverse electric field mode liquid crystal cell, that is, an IPS (In-Plane-Switching) cell.

  In the 1st aspect in the manufacturing method of the composite polarizing plate of this invention, first, a transparent protective film is bonded to the single side | surface of a polarizing film, the peelable film which has adhesiveness is bonded to the surface of an other side, and single side | surface. A polarizing plate with a transparent protective film is produced (step (A)).

(Polarizing film)
The polarizing film used in the method for producing a composite polarizing plate of the present invention has a function of selectively transmitting unidirectional linearly polarized light 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 coating type polarizing film 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 production method of the present invention has a function of selectively transmitting one direction of linearly polarized light from natural light and reflecting or scattering another direction of linearly polarized light as well as the above-described absorption polarizing film. What is called a reflective polarizing film or a scattering 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, it is preferable to use an absorptive polarizing film having excellent visibility, and among them, it is more preferable to use an iodine polarizing film having excellent polarization degree and transmittance as the polarizing film.

  The polyvinyl alcohol resin used for the polyvinyl alcohol film can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins and vinyl ethers.

  The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, and more preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal modified with aldehydes, polyvinyl acetal, polyvinyl butyral, and the like are also used. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1000 to 10000, and preferably about 1500 to 10000.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the thickness of a polyvinyl alcohol-type raw film is not specifically limited, For example, it is about 2-150 micrometers.

  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 the polyvinyl alcohol resin film with a dichroic dye. It is manufactured through a process of dyeing and adsorbing the dichroic dye, a process 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 aqueous boric acid solution. The

  Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing, or may be performed after 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 4 to 8 times. The thickness of the polarizing film obtained by drying after washing with water can be, for example, 1 to 50 μm.

(Transparent protective film)
The transparent protective film used in the production method of the present invention is preferably made of a material having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. Such a material for transparent protective film is not particularly limited. For example, (meth) acrylic resins such as methyl methacrylate resins, chain olefin resins such as polypropylene resins, and cyclic olefin resins. Resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, Polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyamideimide resin and polyimide resin Etc., and the like.

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

  Among these, as the material for the transparent protective film, it is preferable to use (meth) acrylic resins such as methyl methacrylate resins, chain olefin resins such as polyethylene terephthalate resins and polypropylene resins, and cellulose resins. .

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

  This methyl methacrylate resin can be usually obtained by polymerization in the presence of a monofunctional monomer, a polyfunctional monomer, a radical polymerization initiator, and a chain transfer agent mainly composed of methyl methacrylate.

  The monofunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited. For example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methacrylic acid 2 -Methacrylic acid esters other than methyl methacrylate such as ethylhexyl and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate And acrylic esters such as 2-hydroxyethyl acrylate; methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, and -Hydroxyacrylates such as (hydroxymethyl) butyl acrylate; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituted styrene such as vinyltoluene and α-methylstyrene And unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. Such monomers may be used alone or in combination of two or more.

  The polyfunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate , Ethylene glycol such as tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and tetradecaethylene glycol (meth) acrylate, or both ester hydroxyl groups esterified with acrylic acid or methacrylic acid; Propylene glycol or its oligomers with both terminal hydroxyl groups esterified with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate Ester of hydroxyl group of a dihydric alcohol such as bisphenol A and butanediol di (meth) acrylate; acrylic acid or methacrylic acid; alkylene oxide adduct of bisphenol A, bisphenol A, or both terminal hydroxyl groups of these halogen-substituted products Those esterified with acrylic acid or methacrylic acid; those obtained by esterifying polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid, and the epoxy groups of glycidyl acrylate or glycidyl methacrylate opened at the terminal hydroxyl groups Addition: Dibasic acid such as succinic acid, adipic acid, terephthalic acid, phthalic acid, halogen substituted products thereof, and alkylene oxide adducts thereof. Those with an epoxy group of the glycidyl methacrylate to ring-opening addition; aryl (meth) acrylate; and diaryl compounds of divinylbenzene, and the like. Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used.

  As the methyl methacrylate-based resin having such a composition, there may be further used a modified product which undergoes a reaction between functional groups copolymerized with the resin. As the reaction, for example, demethanol condensation reaction in the polymer chain of methyl ester group of methyl acrylate and hydroxyl group of 2- (hydroxymethyl) methyl acrylate, or carboxyl group of acrylic acid and 2- (hydroxymethyl) acrylic Examples thereof include a dehydration condensation reaction within a polymer chain of a hydroxyl group of methyl acid.

  Such methyl methacrylate resin can be easily obtained as a commercial product. For example, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acripet (manufactured by Mitsubishi Rayon Co., Ltd.) under the trade name, respectively. , Delpet (manufactured by Asahi Kasei Co., Ltd.), Parapet (manufactured by Kuraray Co., Ltd.), and Acryviewer (manufactured by Nippon Shokubai Co., Ltd.).

  The polyethylene terephthalate resin means a resin in which 80 mol% or more of repeating units are composed of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. Examples of other dicarboxylic acid components include, but are not limited to, isophthalic acid, p-β-oxyethoxybenzoic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-Carboxyphenyl) ethane, adipic acid, sebacic acid, 1,4-dicarboxycyclohexane and the like.

  Other diol components are not particularly limited, but propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Is mentioned.

  These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. Moreover, oxycarboxylic acids, such as p-oxybenzoic acid, can also be used together. Further, as other copolymerization component, a dicarboxylic acid component or a diol component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used.

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

  The polypropylene resin refers to a polymer obtained by polymerizing a chain olefin monomer in which 80% by weight or more of the repeating unit is a propylene monomer among the chain olefin resins. Among these, a propylene homopolymer is preferable. Also preferred is a copolymer comprising propylene as a main component and a comonomer copolymerizable therewith in an amount of 1 to 20% by weight, preferably 3 to 10% by weight.

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

  Among these, a propylene homopolymer having a component (CXS component) soluble in xylene at 20 ° C. of 1% by weight or less is more preferable, and a propylene homopolymer having a CXS component of 0.5% by weight or less is more preferable.

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

  As a method for making such a methyl methacrylate resin, a polyethylene terephthalate resin, a polypropylene resin, a cellulose resin, and the like as a transparent protective film to be bonded to a polarizing film, a method corresponding to the resin may be appropriately selected. There is no particular limitation. For example, a resin dissolved in a solvent is cast onto a metal band or drum, and the solvent is cast by removing the solvent by drying, and the resin is heated and kneaded above its melting temperature and extruded from a die, A melt extrusion method for obtaining a film by cooling is employed. In this melt extrusion method, a single layer film may be extruded or a multilayer film may be simultaneously extruded.

  Commercially available products can be easily obtained as the transparent protective film thus obtained. For example, methyl methacrylate resin films are sold under the trade names of Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrylite (manufactured by Mitsubishi Rayon Co., Ltd.), Acryprene (manufactured by Mitsubishi Rayon Co., Ltd.), Delaglass (Asahi Kasei). Co., Ltd.), Paragrass (manufactured by Kuraray Co., Ltd.), Comograss (manufactured by Kuraray Co., Ltd.), and Acryviewer (manufactured by Nippon Shokubai Co., Ltd.).

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

  For example, as a polypropylene resin film, FILMAX CPP film (manufactured by FILMAX), Santox (manufactured by Sun Tox Co., Ltd.), Tosero (manufactured by Tosero Co., Ltd.), Toyobo Pyrene Film ( Toyobo Co., Ltd.), Treffan (Toray Film Processing Co., Ltd.), Nihon Polyace (Nihon Polyace Co., Ltd.), Dazai FC (Futamura Chemical Co., Ltd.), and the like.

  Furthermore, for example, as the cellulose-based resin film, Fujitac TD (manufactured by Fuji Film Co., Ltd.), Konica Minolta TAC film KC (manufactured by Konica Minolta Opto Co., Ltd.), and the like can be given as trade names.

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

  The inorganic fine particles for imparting antiglare properties are not particularly limited. For example, silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, carbonic acid. Examples thereof include calcium and calcium phosphate. Further, the organic fine particles are not particularly limited. For example, crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, and polyimide. Particles and the like.

  It is preferable that the haze value of the transparent protective film provided with the antiglare property thus obtained is in the range of 6 to 45%. When the haze value of the transparent protective film is less than 6%, a sufficient antiglare effect may not appear. On the other hand, when the haze value of the transparent protective film exceeds 45%, the screen of the liquid crystal display device using this film may be whitened, resulting in a reduction in image quality.

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

  On the transparent protective film, functional layers such as a conductive layer, a hard coat layer and a low reflection layer can be further laminated. Moreover, the resin composition which has these functions can also be selected for binder resin which comprises a transparent protective film.

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

  The thickness of the transparent protective film is not particularly limited, but is usually about 1 to 500 μm, preferably 20 to 300 μm, and more preferably 20 to 100 μm from the viewpoints of strength and handleability. When the thickness is within this range, the polarizing film is mechanically protected, and even when exposed to high temperature and high humidity, the polarizing film does not shrink and stable optical characteristics can be maintained.

(Adhesive for transparent protective film bonding)
The adhesive used for bonding the polarizing film and the transparent protective film is not particularly limited. For example, a polyvinyl alcohol resin, an epoxy resin, a urethane resin, a cyanoacrylate resin, and an acrylamide resin are used as the adhesive. An adhesive as a component can be mentioned. Among them, a water-based adhesive, that is, an adhesive component dissolved in water or dispersed in water is preferably used because the thickness of the adhesive layer can be further reduced. As another preferable adhesive, an adhesive composed of a solventless resin composition in which a monomer or an oligomer is reactively cured by heating or irradiation with active energy rays to form an adhesive layer can be mentioned.

  First, the water-based adhesive will be described. Examples of the water-based adhesive include those containing, for example, a polyvinyl alcohol resin, a water-soluble crosslinkable epoxy resin, a urethane resin, or the like as an adhesive component. As the polyvinyl alcohol-based resin, various known resins used as water-based adhesives can be used. The water-soluble crosslinkable epoxy resin can be obtained, for example, by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a polyamidopolyamine obtained by reacting a dicarboxylic acid such as adipic acid with epichlorohydrin. Mention may be made of polyamide epoxy resins. Examples of commercially available products of such polyamide epoxy resins include Sumire Resin 650 (manufactured by Sumika Chemtex Co., Ltd.), Sumire Resin 675 (manufactured by Sumika Chemtex Co., Ltd.), and the like.

  When a water-soluble crosslinkable epoxy resin is used as an adhesive component, the adhesive composition is further mixed with another water-soluble resin such as a polyvinyl alcohol resin in order to improve coatability and adhesiveness. It is preferable. Polyvinyl alcohol-based resins include partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, as well as modified carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. 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.

  Examples of suitable commercially available carboxyl group-modified polyvinyl alcohol include Kuraray Poval KL-506 (manufactured by Kuraray Co., Ltd.), Kuraray Poval KL-318 (manufactured by Kuraray Co., Ltd.), and Kuraray Poval KL-118 ((Co., Ltd.). ) Kuraray), GOHSENAL T-330 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), GOHSENAL T-350 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), DR-0415 (manufactured by Denki Kagaku Kogyo Co., Ltd.), AF- 17 (manufactured by Nippon Vinegar-Poval), AT-17 (manufactured by Nippon Vinegar-Poval), AP-17 (manufactured by Nippon Vinegar-Poval)

  The adhesive containing a water-soluble crosslinkable epoxy resin can be prepared as an adhesive solution by dissolving an epoxy resin and other water-soluble resin such as a polyvinyl alcohol resin added as necessary in water. In this case, the content of the water-soluble crosslinkable epoxy resin is preferably about 0.2 to 2 parts by weight with respect to 100 parts by weight of water. Moreover, when mix | blending polyvinyl alcohol-type resin, it is preferable that the compounding quantity shall be about 1-10 weight part with respect to 100 weight part of water, and it is more preferable to set it as about 1-5 weight part.

  On the other hand, examples of urethane resins that can be suitably used for water-based adhesives include ionomer-type urethane resins, particularly polyester-type ionomer-type urethane resins. Here, the ionomer type is obtained by introducing a small amount of an ionic component (hydrophilic component) into the skeleton constituting the urethane resin. The polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced into the skeleton. 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 AP-20 (Dainippon Ink Chemical Co., Ltd.), Hydran APX-101H (Dainippon Ink Chemical Co., Ltd.), etc. Is also available in the form of an emulsion.

  When an ionomer-type urethane resin is used as an adhesive component, it is preferable that an isocyanate-based crosslinking agent is further added to the adhesive composition. The isocyanate-based crosslinking agent is a compound having at least two isocyanato groups (—NCO) in the molecule. For example, 2,4-tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,6-hexa In addition to polyisocyanate monomers such as methylene diisocyanate and isophorone diisocyanate, adducts in which a plurality of these molecules are added to a polyhydric alcohol such as trimethylolpropane, and three molecules of diisocyanate are isocyanurates at each end isocyanato group And polyisocyanate modified products such as burettes formed by hydration and decarboxylation of trifunctional isocyanurate having a ring formed and three diisocyanate molecules at the respective one-end isocyanate groups. Examples of commercially available isocyanate-based crosslinking agents that can be suitably used include hydran assistar C-1 (manufactured by Dainippon Ink & Chemicals, Inc.).

  In an aqueous adhesive containing an ionomer type urethane resin, from the viewpoint of viscosity and adhesiveness, the urethane resin is preferably dissolved or dispersed in water so that its concentration is about 10 to 70% by weight. More preferred is ˜50% by weight or less. Moreover, when mix | blending an isocyanate type crosslinking agent, the compounding quantity is suitably selected so that an isocyanate type crosslinking agent may be about 5-100 weight part with respect to 100 weight part of urethane type resins.

  In the case of using the aqueous adhesive thus formed, the adhesive is applied to the adhesive surface of the transparent protective film or the polarizing film, and the laminated body of the polarizing film and the transparent protective film is obtained by bonding and drying both. be able to.

  Next, an adhesive made of a solventless resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating will be described.

  The adhesive used in the production method of the present invention is a curable composition that contains a curable compound that is polymerized by heating or irradiation with active energy rays and a polymerization initiator and does not contain a significant amount of solvent. This curable compound is preferably one that is cured by cationic polymerization from the viewpoint of reactivity, and particularly preferably contains an epoxy compound (epoxy resin).

  As this epoxy compound, those having no aromatic ring in the molecule are suitably used from the viewpoint of weather resistance, refractive index and the like. 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, and aliphatic epoxy compounds.

  A hydride of an aromatic epoxy compound is 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 diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin, And a novolak type epoxy resin such as hydroxybenzaldehyde phenol novolac epoxy resin; a glycidyl ether of tetrahydroxydiphenylmethane, a glycidyl ether of tetrahydroxybenzophenone, and a polyfunctional type epoxy compound such as epoxidized polyvinylphenol. Of these, hydrogenated diglycidyl ether of bisphenol A is preferred.

  An alicyclic epoxy compound is a compound having at least one epoxy group bonded to an alicyclic ring in the molecule, as shown in the following formula.

(In the formula, m represents an integer of 2 to 5.)
A compound in which one or more hydrogen atoms in (CH ₂ ) _m in this formula are removed and bonded to 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-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)
4- (3,4-epoxycyclohexyl) -2,6-dioxa-8,9-epoxyspiro [5.5] undecane,
4-vinylcyclohexene dioxide,
Bis-2,3-epoxycyclopentyl ether, and
Dicyclopentadiene dioxide.

  The aliphatic epoxy compound is a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. For example, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl Polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or polypropylene oxide) to aliphatic polyhydric alcohols such as ether, ethylene glycol, polypropylene glycol, and glycerin, etc. Is mentioned.

  The epoxy compounds illustrated here may be used alone or in combination with a plurality of epoxy compounds.

  The epoxy equivalent of such an epoxy compound is usually 30 to 3000 g / eq, and preferably 50 to 1500 g / eq. When the epoxy equivalent is less than 30 g / eq, the flexibility of the transparent protective film after curing may decrease or the adhesive strength may decrease. On the other hand, when it exceeds 3000 g / eq, the compatibility with other components may decrease.

  A cationic polymerization initiator is blended with the curable composition in order to cure the epoxy compound by cationic polymerization. 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, and electron beams, or by heating, and initiates a polymerization reaction of an epoxy group. Regardless of the type of cationic polymerization initiator, it is preferable from the viewpoint of workability that latency is imparted.

  Hereinafter, a photocationic polymerization initiator that generates a cationic species or a Lewis acid by irradiation with active energy rays will be described. Use of a cationic photopolymerization initiator enables curing at room temperature, reduces the need to consider the internal stress due to heat resistance or thermal expansion of the polarizing film, and allows the transparent protective film and the polarizing film to adhere well. it can. 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 the compound that generates a cationic species or a Lewis acid 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 since 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.

  Such a cationic photopolymerization initiator can be easily obtained as a commercial product. For example, Kayrad PCI-220 (manufactured by Nippon Kayaku Co., Ltd.) and Kayrad PCI-620 (manufactured by Nippon Kayaku Co., Ltd.) under the trade names, respectively. ), UVI-6990 (manufactured by Union Carbide), Adekaoptomer SP-150 (manufactured by ADEKA), Adekaoptomer SP-170 (manufactured by ADEKA), CI-5102 (manufactured by Nippon Soda Co., Ltd.) ), CIT-1370 (manufactured by Nippon Soda Co., Ltd.), CIT-1682 (manufactured by Nippon Soda Co., Ltd.), CIP-1866S (manufactured by Nippon Soda Co., Ltd.), CIP-2048S (manufactured by Nippon Soda Co., Ltd.), CIP-2064S (manufactured by Nippon Soda Co., Ltd.), DPI-101 (manufactured by Midori Kagaku Co., Ltd.), DPI-102 (manufactured by Midori Kagaku Co., Ltd.), DPI-103 (green) DPI-105 (manufactured by Midori Chemical Co., Ltd.), MPI-103 (manufactured by Midori Chemical Co., Ltd.), MPI-105 (manufactured by Midori Chemical Co., Ltd.), BBI-101 (manufactured by Midori Chemical Co., Ltd.) )), BBI-102 (manufactured by Midori Chemical Co., Ltd.), BBI-103 (manufactured by Midori Chemical Co., Ltd.), BBI-105 (manufactured by Midori Chemical Co., Ltd.), TPS-101 (manufactured by Midori Chemical Co., Ltd.) ), TPS-102 (manufactured by Midori Chemical Co., Ltd.), TPS-103 (manufactured by Midori Chemical Co., Ltd.), TPS-105 (manufactured by Midori Chemical Co., Ltd.), MDS-103 (manufactured by Midori Chemical Co., Ltd.), Examples thereof include MDS-105 (manufactured by Midori Chemical Co., Ltd.), DTS-102 (manufactured by Midori Chemical Co., Ltd.), DTS-103 (manufactured by Midori Chemical Co., Ltd.), PI-2074 (manufactured by Rhodia).

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of epoxy compounds, and 1 weight part-15 weight part is preferable.

  A photosensitizer can be used in combination with the curable composition as 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 mix | blending a photosensitizer, the compounding quantity is about 0.1-20 weight part normally about 100 weight part of photocationic polymerizable epoxy resin compositions.

  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. Commercially available products of these thermal cationic polymerization initiators can also be easily obtained. For example, they are trade names such as Adeka Opton CP77 (manufactured by ADEKA), Adeka Opton CP66 (manufactured by ADEKA), CI- 2639 (manufactured by Nippon Soda Co., Ltd.), CI-2624 (manufactured by Nippon Soda Co., Ltd.), Sun-Aid SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.), Sun-Aid SI-80L (manufactured by Sanshin Chemical Industry Co., Ltd.) ), Sun Aid SI-100L (manufactured by Sanshin Chemical Industry Co., Ltd.) and the like.

It is also a useful technique to use the above cationic photopolymerization and thermal cationic polymerization together.
The epoxy-based adhesive may further contain a compound that promotes cationic polymerization such as oxetanes and polyols.

  The adhesive comprising the curable composition thus obtained is applied to the adhesive surface of the transparent protective film or the polarizing film, and after both are laminated, the adhesive is cured to laminate the polarizing film and the transparent protective film. You can get a body. There is no particular limitation on the method of applying this adhesive to the transparent protective film or polarizing film, and various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater are employed. . The thickness of the adhesive layer is usually 1 μm or more and 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.

When the adhesive is cured by irradiation with active energy rays, 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, Examples include ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. The light irradiation intensity to the adhesive composition is determined by the curability of the composition and is not particularly limited. For example, the light irradiation intensity in the wavelength region effective for activating the photocationic polymerization initiator is used. The irradiation intensity is preferably 0.1 to 100 mW / cm ² . When the light irradiation intensity to the adhesive composition is less than 0.1 mW / cm ² , the reaction time becomes too long, and when it exceeds 100 mW / cm ² , the heat radiated from the lamp and the curable epoxy resin composition The heat generated during the polymerization may cause yellowing of the curable epoxy resin composition or deterioration of the polarizing film. Similarly, the light irradiation time for the adhesive composition is determined by the curability of the composition, and is not particularly limited. For example, it is expressed as a product of irradiation intensity and irradiation time. It is preferable that the integrated light quantity to be set is 10 to 5000 mJ / cm ² . When the integrated light quantity to the curable epoxy resin composition is less than 10 mJ / cm ² , the generation of active species derived from the photocationic polymerization initiator is not sufficient, and the adhesive may be insufficiently cured. On the other hand, if the integrated light quantity exceeds 5000 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity.

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

  Even if it is cured under any condition of irradiation with active energy rays or heating, it should be cured as long as the functions such as polarization degree, transmittance, hue, transparency of the transparent protective film of the polarizing plate with a single-sided protective film do not deteriorate. Is preferred. The thickness of the cured layer formed by curing the adhesive composition is usually 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.

(Peelable film)
As the peelable film having adhesiveness used in the production method of the present invention, a film which has been treated with a low molecular weight pressure-sensitive adhesive so as to be easily peeled can be used. For example, polyesters such as polyethylene terephthalate and polyethylene naphthalate Resin; Cyclic olefin resin; Chain olefin resin such as polyethylene, polypropylene and propylene / ethylene copolymer can be used. Among these, a polyethylene terephthalate film, a polypropylene film, or a polyethylene film is preferably used from the viewpoint that the adhesiveness can be adjusted as appropriate and a commercially available product is easily available.

  The peelable film has self-adhesiveness and can be directly bonded to the surface of the polarizing film opposite to the surface to which the transparent protective film is bonded.

  Thus, a polarizing plate with a single-sided transparent protective film in which a transparent protective film is bonded to one side of a polarizing film by an adhesive and a peelable film having adhesiveness is bonded to the opposite side is once a winding device. Is wound around a core such as a vinyl chloride tube. In addition, either the process of bonding a transparent protective film to a polarizing film and the process of bonding a peelable film to a polarizing film may be performed first, and may be performed simultaneously.

  In the first aspect of the method for producing a composite polarizing plate of the present invention, the polarizing plate with a single-sided transparent protective film produced as described above is then aligned along the longitudinal direction according to the width of the retardation film. Cut (slit) (step (B)). The width after cutting of the polarizing plate with a single-sided transparent protective film is appropriately set according to the width of the retardation film described later. For example, at least one fragment of the polarizing plate with a single-sided transparent protective film after cutting will be described later. The width is preferably the same as the width of the retardation film.

  The method of cutting the polarizing plate with a single-sided transparent protective film is not particularly limited, but usually the rolled-up polarizing plate with a single-sided transparent protective film is fed simultaneously to a slitter (long-direction cutting machine). Then, a method of rewinding the cut pieces is adopted. Moreover, the process (C) of removing a peelable film from there without winding up the polarizing plate cut according to the width | variety of retardation film, and forming an adhesive layer in the polarizing film surface from which the peelable film was removed It is also possible to adopt a method of sequentially sending to the step (D) to be performed and the step (E) for bonding the retardation film to the pressure-sensitive adhesive layer.

  In the first aspect of the method for producing a composite polarizing plate of the present invention, next, the peelable film of the polarizing plate with a single-sided transparent protective film cut in the step (B) is removed (step (C)), An adhesive layer having a storage elastic modulus of 0.1 MPa or more at 80 ° C. is formed on the polarizing film surface (the surface on which the peelable film has been bonded) (step (D)).

(Adhesive)
The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer has a storage elastic modulus at 80 ° C. of 0.1 MPa or more, preferably 0.15 MPa to 10 MPa. When the storage elastic modulus at 80 ° C. is less than 0.1 MPa, there is a problem that bubbles and peeling occur because the dimensional change of the polarizing film that occurs when the high temperature environment and the low temperature environment are repeated cannot be followed. Because. Moreover, the storage elastic modulus at a temperature of 23 ° C. of this pressure-sensitive adhesive is preferably 0.1 MPa or more, and more preferably 0.2 to 10 MPa. 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.

  Here, the storage elastic modulus (dynamic elastic modulus) is a commonly used term for viscoelasticity measurement, and gives a strain or stress that changes (vibrates) over time to a sample. This is a value determined by a method (dynamic viscoelasticity measurement) for measuring the mechanical properties of a sample by measuring the stress or strain generated by. Specifically, when the stress (strain) generated by the sinusoidal strain (stress) applied to the sample is divided into a component having the same phase as the strain (stress) and a component having a phase shifted by 90 degrees, The elastic modulus calculated from the stress (strain) component in phase with the 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. 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.

  The pressure-sensitive adhesive used in a normal image display device or an optical film applied thereto has a storage elastic modulus of about 0.1 MPa at most, but the pressure-sensitive adhesive used in the production method of the present invention is as described above. The storage elastic modulus is high. By using such a high storage elastic modulus, that is, a hard adhesive, it is possible to compensate for the lack of cohesive force when placed in a high temperature environment or when a high temperature environment and a low temperature environment are repeated. The dimensional change accompanying the shrinkage | contraction of the polarizing film sometimes generated can be suppressed. By this action, the composite polarizing plate of the present invention has good durability.

  As a specific high elastic pressure-sensitive adhesive used in the production method of the present invention, for example, it can be composed of a composition mainly containing acrylic polymer, silicone polymer, polyester, polyurethane, polyether and the like. Above all, like acrylic polymer, it has excellent optical transparency, moderate wettability and cohesion, excellent adhesion to the substrate, weather resistance, heat resistance, etc. It is preferable to select and use one that does not cause peeling problems such as floating and peeling under humidifying conditions. 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 and 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 a group-containing acrylic monomer with a glass transition temperature of preferably 25 ° C. or lower, more preferably 0 ° C. or lower is useful.

  The acrylic polymer is not particularly limited, but (meth) such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. An acrylic ester polymer and a copolymer polymer using two or more of these (meth) acrylic esters are preferably used. Moreover, polar monomers may be copolymerized with these acrylic 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, and epoxy groups, such as acrylates and glycidyl (meth) acrylates.

  These acrylic polymers can be used alone as a pressure-sensitive adhesive, but are usually a pressure-sensitive adhesive composition containing a crosslinking agent. 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 an amide bond with a carboxyl group. Of these, polyisocyanate compounds are preferably used.

  The means for increasing the storage elastic modulus of the pressure-sensitive adhesive is not particularly limited. For example, an oligomer, specifically, a urethane acrylate-based oligomer is added to the above-mentioned pressure-sensitive adhesive composition. A method is preferably employed. Furthermore, a method of irradiating and curing an adhesive composition containing such a urethane acrylate oligomer with energy rays is more preferably employed because it has a higher storage elastic modulus. A pressure-sensitive adhesive containing a urethane acrylate-based 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 can be obtained from a pressure-sensitive adhesive manufacturer.

  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 above-described polymer, crosslinking agent and oligomer, Appropriate additives such as natural and synthetic resins, tackifier resins, antioxidants, ultraviolet absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors and photopolymerization initiators may be added. it can. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

  Moreover, the adhesive used by the manufacturing method of this invention can mix | blend a light-diffusion agent, and can be used as a light diffusable adhesive. The light diffusing agent used here may be fine particles having a refractive index different from that of the polymer constituting the pressure-sensitive adhesive layer, and 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 comprising an organic compound (polymer) include melamine beads (refractive index: 1.57), polymethyl methacrylate beads (refractive index: 1.49), and 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) and silicone resin beads (refractive index: 1.46).

  Since the resin composition constituting the pressure-sensitive adhesive layer including the acrylic polymer usually has a refractive index of around 1.4, the light diffusing agent to be blended is appropriately selected from those having a refractive index of about 1-2. Just choose. The refractive index difference between the polymer and the light diffusing agent in the composition constituting the pressure-sensitive adhesive layer is usually 0.01 or more, and from the viewpoint of the brightness and visibility of the image display device, 0.01 to 0.00. 5 is preferred. The fine particles used as the light diffusing agent are preferably spherical and those close to monodisperse. For example, fine particles having an average particle diameter in the range of about 2 to 6 μm 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, etc. 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.

  In addition, the haze value required for the light diffusive pressure-sensitive adhesive layer ensures the brightness of the image display device to which the composite polarizing plate obtained by using the haze value is applied, and hardly causes bleeding and blurring of the display image. From the viewpoint of making, a range of 20 to 80% is preferable. The haze is a value defined by JIS K 7105 and expressed by (diffuse transmittance / total light transmittance) × 100 (%).

  Although the thickness of an adhesive layer and the thickness of a light diffusable adhesive layer are determined according to the adhesive force etc., they are the range of 1-40 micrometers normally. Furthermore, this thickness is such that the composite polarizing plate produced using the composite polarizing plate maintains good workability and exhibits high durability, and the image display device using the composite polarizing plate is viewed from the front or obliquely. 3 to 25 μm is more preferable from the standpoint of maintaining the brightness of the image and preventing the display image from blurring or blurring.

  In the 1st aspect in the manufacturing method of the composite polarizing plate of this invention, the polarizing film surface (surface with which the peelable film was bonded) of the polarizing plate with a single-sided transparent protective film from which the peelable film was cut and cut | disconnected. On the top, the pressure-sensitive adhesive layer as described above is formed (step (D)).

  For the formation of the pressure-sensitive adhesive layer, a method of applying a pressure-sensitive adhesive solution to the polarizing film surface of the cut polarizing plate with a single-sided transparent protective film and drying it is preferably employed. Also preferred is a method in which a release film-treated surface of a support film (separator) that has been subjected to a release treatment is prepared (adhesive with a separator) having a pressure-sensitive adhesive layer formed thereon, and is bonded to the polarizing film surface. Adopted.

  As the pressure-sensitive adhesive solution, for example, a solution obtained by dissolving or dispersing the raw material constituting the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to obtain a solution of 10 to 40% by weight, for example, is used. The pressure-sensitive adhesive layer thus formed may be laminated with a separator made of a resin film that has been treated with a silicone-based release agent.

  Furthermore, when forming the pressure-sensitive adhesive layer on the polarizing film surface of the polarizing plate with a single-sided transparent protective film, if necessary, a treatment for improving adhesion to the polarizing film surface, for example, corona treatment, etc. You may give, and the same process may be given to the surface of the adhesive layer bonded together to a polarizing film surface.

  In the first aspect of the method for producing a composite polarizing plate of the present invention, a polarizing plate with a single-side transparent protective film and a retardation film, which are then cut, the peelable film is removed, and a pressure-sensitive adhesive layer is further formed, Are bonded through the pressure-sensitive adhesive layer (step (E)).

(Retardation film)
In the retardation film used in the production method of the present invention, the core layer is made of a styrene resin, and the skin layer made of a (meth) acrylic resin composition containing rubber particles is formed on both surfaces thereof. is there.

  The styrenic resin constituting the core layer can be a homopolymer of styrene or a derivative thereof, or is a binary or higher copolymer of styrene or a derivative thereof and another copolymerizable monomer. You can also. Here, the styrene derivative is a compound in which another group is bonded to styrene, such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, o-ethylstyrene, alkyl styrenes such as p-ethylstyrene; and hydroxystyrene, tert-butoxystyrene, vinylbenzoic acid, o-chlorostyrene, p-chlorostyrene, benzene nucleus of styrene with hydroxyl group, alkoxy group, carboxyl group, Examples thereof include substituted styrene introduced with halogen or the like. 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. In order to improve the heat resistance of the core layer, the styrene resin constituting the core layer preferably has a glass transition temperature Tg of 100 ° C. or higher, and more preferably 120 ° C. or higher.

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

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

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

  The content of the rubber particles in the (meth) acrylic resin composition constituting the skin layer 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 (manufactured by Sumitomo Chemical Co., Ltd.) and Technoloy (registered trademark) S001 (manufactured by Sumitomo Chemical Co., Ltd.). Such an acrylic rubber particle-containing (meth) acrylic resin composition generally has a Tg of 160 ° C. or lower, and a preferable Tg thereof is 120 ° C. or lower, and further 110 ° C. or lower.

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

  As described above, in the retardation film used in the present invention, the core layer made of a styrene resin preferably has a Tg of 120 ° C. or higher, while a (meth) acrylic resin composition containing rubber particles. The skin layer made of a material preferably has a Tg of 120 ° C. or lower, more preferably 110 ° C. or lower. During stretching, the core layer made of styrene resin positively orients the polymer main chain and selectively develops anisotropy, while the skin layer is not only optical but also dynamic. Since it is preferable to make the polymer chain closer to an isotropic structure without aligning the polymer chain as much as possible, the Tg of the two do not overlap, and the core layer made of styrene resin is blended with rubber particles (meta ) It is preferable to have a higher Tg than a skin layer made of an acrylic resin composition.

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

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

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

  In addition, the retardation film contains other components such as residual solvent, stabilizer, plasticizer, anti-aging agent, antistatic agent, and ultraviolet absorber as necessary, as long as the object of the present invention is not impaired. It may be. Further, a leveling agent can be contained in order to reduce the surface roughness.

  The width of the retardation film is preferably 10% or more smaller than the polarizing plate with a single-sided transparent protective film produced in the step (A), because the effect of improving productivity stands out. Furthermore, if the width is in the range of 40 to 50% of the polarizing plate, by slitting the polarizing plate with a single-sided transparent protective film to the half width, both of them are used for bonding with the retardation film. Is more preferable because

  The method for laminating the polarizing plate with a single-sided transparent protective film on which the pressure-sensitive adhesive layer is laminated and the retardation film is not particularly limited, but for example, with a single-sided transparent protective film using a laminating roll or the like. A method of laminating the retardation film so that the slow axis of the retardation film is perpendicular or parallel to the polarizing transmission axis of the polarizing plate, and the slow axis of the retardation film is a predetermined angle with respect to the polarizing transmission axis of the polarizing film. The method of bonding so that it becomes is employ | adopted. In particular, the method of feeding a polarizing plate with a single-sided transparent protective film and a retardation film from each long roll and continuously bonding them together in the long side direction can produce a composite polarizing plate with high productivity. Preferably employed.

  Next, the second aspect in the method for producing the composite polarizing plate of the present invention will be described. In the second aspect, the steps (A) to (E) are performed in the order of the step (A), the step (C), the step (D), the step (B), and the step (E). . Specifically, first, similarly to the first embodiment, a polarizing plate with a single-sided transparent protective film is produced (step (A)). The production of the transparent protective film and the polarizing film, the bonding between the transparent protective film and the polarizing film, and the bonding between the peelable film and the polarizing film are performed in the same manner as in the step (A) of the first aspect.

  Next, the peelable film of the polarizing plate with a single-sided transparent protective film is removed (step (C)), and an adhesive layer having a storage elastic modulus of 0.1 MPa or more at 80 ° C. is formed on the polarizing film surface. (Step (D)). The removal of the peelable film and the formation of the pressure-sensitive adhesive layer are performed in the same manner as in the steps (C) and (D) of the first aspect.

  Next, the polarizing plate with a single-sided transparent protective film on which the pressure-sensitive adhesive layer has been formed is cut along the longitudinal direction in accordance with the width of the retardation film (step (B)). The cutting of the polarizing plate with a single-sided transparent protective film can be performed in the same manner as in the step (B) of the first aspect. In addition, cutting of the polarizing plate with a single-sided transparent protective film is made for each laminated adhesive layer.

  Finally, similarly to the process (E) of the first aspect, the cut polarizing plate with a single-sided transparent protective film having a pressure-sensitive adhesive layer and the retardation film are bonded via the pressure-sensitive adhesive layer. The configuration of the retardation film and the production method thereof are the same as those described in the first embodiment. The composite polarizing plate thus obtained has the same configuration as the composite polarizing plate obtained by the first aspect in the method for producing a composite polarizing plate of the present invention.

  Next, the 3rd aspect in the manufacturing method of the composite polarizing plate of this invention is demonstrated. In a 3rd aspect, performing a process (A), a process (B), a process (C), and a process (E) in this order among processes (A)-(E) with which the manufacturing method of the present invention is provided. Features. Specifically, first, similarly to the first and second embodiments, a polarizing plate with a single-sided transparent protective film is produced (step (A)). The production of the transparent protective film and the polarizing film, the bonding between the transparent protective film and the polarizing film, and the bonding between the peelable film and the polarizing film are performed in the same manner as in the step (A) of the first aspect.

  Next, as in the first and second aspects, the polarizing plate with a single-sided transparent protective film is cut along the longitudinal direction according to the width of the retardation film (step (B)). The cutting of the polarizing plate with a single-sided transparent protective film can be performed in the same manner as in the step (B) of the first aspect. A peelable film is removed from the cut polarizing plate with a single-sided transparent protective film (step (C)).

  On the other hand, in a 3rd aspect, the adhesive layer which has a storage elastic modulus of 0.1 Mpa or more in 80 degreeC is formed on a phase difference film surface (process (D)). The configuration of the retardation film and the production method thereof are the same as those described in the first embodiment. Moreover, lamination | stacking of the adhesive layer to a phase difference film can be performed like the process (D) of a 1st aspect. 3rd aspect WHEREIN: The timing at which a process (D) is implemented is not specifically limited, What is necessary is just to be implemented by the below-mentioned process (E) being made. That is, step (D) may be performed before step (A), or in parallel with or after any of step (A), step (B) and step (C). Also good. In short, the retardation film with the pressure-sensitive adhesive layer may be supplied to the polarizing film surface from which the peelable film has been removed in the step (C).

  Finally, in the same manner as in the step (E) of the first aspect, the pressure-sensitive adhesive layer is obtained by cutting the polarizing plate with the single-sided transparent protective film from which the peelable film has been removed and the retardation film having the pressure-sensitive adhesive layer. Pasted through. The composite polarizing plate thus obtained has the same configuration as the composite polarizing plate obtained by the first and second embodiments in the method for producing a composite polarizing plate of the present invention.

  In the method for producing a composite polarizing plate of the present invention, an adhesive layer may be provided on the outer surface of the retardation film in the composite polarizing plate. The pressure-sensitive adhesive layer can be suitably used for bonding with other members such as a liquid crystal cell. This pressure-sensitive adhesive layer may be formed after producing the composite polarizing plate, or may be formed in advance on the retardation film before bonding the polarizing plate with a single-sided transparent protective film and the retardation film. The composite polarizing plate thus formed is usually arranged so that the retardation film side faces the liquid crystal cell when being bonded to the liquid crystal cell.

<Liquid crystal display device>
The composite polarizing plate manufactured by the manufacturing method of this invention can be set as a liquid crystal display device by bonding the retardation film side and a liquid crystal cell through an adhesion layer. The same type of polarizing plate or a known polarizing plate can be bonded to the back side of the liquid crystal display device to which the composite polarizing plate is bonded. In addition, the operation mode of the liquid crystal panel to be bonded is preferably an IPS (In-Plane-Switching) mode in which optical compensation is favorably performed by the refractive index characteristics of the composite polarizing plate of the present invention.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “part” and “%” representing the amount used or content are based on weight unless otherwise specified. In the following examples, the storage elastic modulus was measured by the following method.

[Method for measuring storage modulus]
The storage elastic modulus (G ′) of the pressure-sensitive adhesive is a disk-shaped test piece having a diameter of 8 mm × thickness of 1 mm made of the pressure-sensitive adhesive to be measured, and a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by REOMETRIC). The initial strain was set to 1N by the torsional shear method with a frequency of 1 Hz, and the measurement was performed at 23 ° C. and 80 ° C.

  Moreover, in the Example and comparative example mentioned later, the following were used as an adhesive, an adhesive agent, a polarizing film, and retardation film.

(Adhesive sheet A)
The pressure-sensitive adhesive A constituting the pressure-sensitive adhesive sheet A is obtained by adding a urethane acrylate oligomer to a copolymer of butyl acrylate and acrylic acid and further adding an isocyanate-based crosslinking agent. When the storage elastic modulus of this adhesive A was measured by the above method, it was 0.40 MPa at 23 ° C. and 0.18 MPa at 80 ° C. In the following examples, the adhesive was applied to the release treatment surface of a 38 μm-thick polyethylene terephthalate film (separator) having been subjected to the release treatment by drying the organic solvent solution having the above composition, and dried. The separator was used as a sheet-like pressure-sensitive adhesive (pressure-sensitive adhesive sheet A) in which a layer of pressure-sensitive adhesive A having a thickness of 15 μm was formed on the surface of the separator.

(Adhesive sheet B)
The pressure-sensitive adhesive sheet B is a commercially available sheet-like pressure-sensitive adhesive and does not contain a urethane acrylate oligomer. When the storage elastic modulus of the adhesive B constituting the adhesive sheet B was measured by the above method, it was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C. In the following examples and comparative examples, as the pressure-sensitive adhesive sheet B, a layer of pressure-sensitive adhesive B having a thickness of 15 μm is provided on the release treatment surface of a 38 μm-thick polyethylene terephthalate film (separator) subjected to the release treatment. A commercially available sheet-like pressure-sensitive adhesive with a separator was used.

(Adhesive A)
To 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol (Kuraray Poval KL318, manufactured by Kuraray Co., Ltd.) and water-soluble polyamide epoxy resin (Smiles Resin 650, manufactured by Sumika Chemtex Co., Ltd.) (solid content concentration 30%) Aqueous solution) 1.5 parts was added and dissolved to prepare adhesive A.

(Adhesive B)
100 parts of bis (3,4-epoxycyclohexylmethyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A, and 4,4′-bis (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate as a photocationic polymerization initiator ) (50% propylene carbonate solution) 2.2 parts (active ingredient amount) were mixed and defoamed to prepare an adhesive B made of a curable epoxy resin composition.

(Polarizing film)
A 75 μm-thick polyvinyl alcohol film made of polyvinyl alcohol having an average degree of polymerization of about 2400 and a saponification degree of 99.9 mol% or more was uniaxially stretched about 5 times by a dry method, and further maintained a 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.

(Retardation film)
Styrene-maleic anhydride copolymer resin (“Dylark® D332” (Tg = 131 ° C.) manufactured by Nova Chemical Co., Ltd.) is used as a core layer, and about 20% of acrylic rubber particles having an average particle size of 200 nm are blended. Methacrylic resin [resin used in “Technoloy (registered trademark) S001” manufactured by Sumitomo Chemical Co., Ltd. (Tg = 105 ° C.)] is used as a skin layer, and three-layer coextrusion is performed. A resin three-layer film having a skin layer of 60 μm and a thickness of 72 μm on each side was obtained. 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. Further, the width of the obtained long retardation film was 720 mm.

<Example 1>
[Step (A)]
A 40 μm-thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive A, and the opposite surface has adhesiveness. As a peelable film, a polarizing film in which a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) is bonded, the laminate is dried at 60 ° C., and a transparent protective film is bonded on one side is used. Obtained. The width of the obtained long polarizing plate with a single-sided transparent protective film was 1490 mm. The appearance of the polarizing plate with a single-sided protective film was good with no damage such as scratches and cracks, despite the heat of drying and friction with the transport roll.

[Step (B)]
Subsequently, this polarizing plate with a single-sided transparent protective film was cut (slit) along the longitudinal direction according to the width of the retardation film using a slitter (Model FN25, manufactured by Nishimura Seisakusho Co., Ltd.), and 720 mm wide A polarizing plate with a single-sided transparent protective film was obtained. The appearance of the slit polarizing plate was good without damage such as scratches and cracks despite being subjected to shearing during slitting and friction with the transport roll.

[Steps (C) and (D)]
The polyethylene film was peeled and removed from the polarizing plate cut in the step (B), and the pressure-sensitive adhesive sheet A was immediately bonded onto the polarizing film surface.

[Step (E)]
After the corona treatment is applied to the retardation film at an irradiation amount of 16.8 kJ / m ² , the corona-treated surface and the polarizing plate with the single-sided transparent protective film slit in the step (B) are used in the step (C). And it bonded through the adhesive layer provided by (D), and obtained the composite polarizing plate.

  The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.

  The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) using an adhesive sheet 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 a −35 ° C. atmosphere for 30 minutes, then moving to a + 85 ° C. atmosphere and placing in 30 minutes for one cycle, and repeating this for 100 cycles. The composite polarizing plate of Example 1 maintained a good state with no defects observed after the test.

<Comparative Example 1>
A composite polarizing plate was produced in the same manner as in Example 1 except that the polarizing plate with a single-sided transparent protective film was not cut. The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. However, in obtaining the sheet in the same manner as in Example 1, only 48.3% of the total area of the composite polarizing plate could be used.

<Comparative example 2>
A composite polarizing plate was prepared in the same manner as in Example 1 except that a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) was not used when the polarizing plate with a single-sided transparent protective film was prepared. The appearance of the produced composite polarizing plate was not practically used because the polarizing film was damaged during the production of the polarizing plate with a single-sided transparent protective film and when the polarizing plate with a single-sided transparent protective film was cut.

<Example 2>
[Step (A)]
A 40 μm thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive B, and the opposite surface has adhesiveness. As a peelable film, a polyethylene film having a self-adhesive surface (bonding surface with a polarizing film) is bonded, and ultraviolet irradiation is performed with an ultraviolet irradiation device (lamp: Fusion D lamp, integrated light quantity: 1000 mJ / cm ² ). And left at room temperature for 1 hour to obtain a polarizing plate having a transparent protective film bonded on one side. The width of the obtained long polarizing plate with a single-sided transparent protective film was 1490 mm. In addition, the appearance of the polarizing plate with a single-side protective film was good without damage such as scratches and cracks, despite being subjected to friction with the transport roll.

[Step (B)]
Next, this polarizing plate with a single-sided transparent protective film was cut in the same manner as in Example 1 to obtain a polarizing plate with a single-sided transparent protective film having a width of 720 mm. The appearance of the polarizing plate with a single-sided transparent protective film after the cutting was good without damage such as scratches and cracks, despite being sheared at the time of slitting and friction with the transport roll.

[Steps (C) and (D)]
The polyethylene film was peeled and removed from the polarizing plate slit in the step (B), and the pressure-sensitive adhesive sheet A was immediately bonded onto the surface of the polarizing film.

[Step (E)]
After the corona treatment is applied to the retardation film at an irradiation amount of 16.8 kJ / m ² , the corona-treated surface and the polarizing plate with the single-sided transparent protective film slit in the step (B) are used in the step (C). And it bonded through the adhesive layer provided by (D), and obtained the composite polarizing plate.

  The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, in obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% of the total area of the polarizing plate with a single-sided protective film could be used.

  The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) using an adhesive sheet 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 a −35 ° C. atmosphere for 30 minutes, then moving to a + 85 ° C. atmosphere and placing in 30 minutes for one cycle, and repeating this for 100 cycles. The composite polarizing plate of Example 2 maintained a good state with no defects observed after the test.

<Comparative Example 3>
In Example 1, a composite polarizing plate was produced in the same manner except that the pressure-sensitive adhesive sheet A used in the step (D) was changed to the pressure-sensitive adhesive sheet B. The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.

  The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to adhere the composite polarizing plate to the glass plate. I let you. In this state, a heat shock test was performed by placing in a −35 ° C. atmosphere for 30 minutes, then moving to a + 85 ° C. atmosphere and placing in 30 minutes for one cycle, and repeating this for 100 cycles. In the 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.

<Comparative example 4>
In Example 2, a composite polarizing plate was produced in the same manner except that the pressure-sensitive adhesive sheet A used in the step (D) was changed to the pressure-sensitive adhesive sheet B. The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.

  The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to adhere the composite polarizing plate to the glass plate. I let you. In this state, a heat shock test was performed by placing in a −35 ° C. atmosphere for 30 minutes, then moving to a + 85 ° C. atmosphere and placing in 30 minutes for one cycle, and repeating this for 100 cycles. In the polarizing plate of Comparative Example 4, bubbles were generated in the pressure-sensitive adhesive layer between the retardation film and the glass after the test, which was not practical.

<Example 3>
[Step (A)]
A 40 μm-thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive A, and the opposite surface has adhesiveness. As a peelable film, a polarizing film in which a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) is bonded, the laminate is dried at 60 ° C., and a transparent protective film is bonded on one side is used. Obtained. The width of the obtained long polarizing plate with a single-sided transparent protective film was 1490 mm. The appearance of this polarizing plate with a single-sided protective film was good without damage such as scratches and cracks, despite the heat of drying and friction with the transport roll.

[Steps (C) and (D)]
Subsequently, the polyethylene film was peeled and removed from the polarizing plate with a single-sided transparent protective film, and immediately, the pressure-sensitive adhesive sheet A was bonded onto the polarizing film surface.

[Step (B)]
Using a slitter (Model FN25, manufactured by Nishimura Seisakusho Co., Ltd.), the polarizing plate with a single-sided transparent protective film was cut (slit) along the longitudinal direction according to the width of the retardation film, and the single-sided surface having a width of 720 mm A polarizing plate with a transparent protective film was obtained. The appearance of the slit polarizing plate was good without damage such as scratches and cracks despite being subjected to shearing during slitting and friction with the transport roll.

[Step (E)]
After the corona treatment is applied to the retardation film at an irradiation amount of 16.8 kJ / m ² , the corona-treated surface and the polarizing plate with the single-sided transparent protective film slit in the step (B) are used in the step (C). And it bonded through the adhesive layer provided by (D), and obtained the composite polarizing plate.

  The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.

<Example 4>
[Step (A)]
A 40 μm-thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive A, and the opposite surface has adhesiveness. As a peelable film, a polarizing film in which a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) is bonded, the laminate is dried at 60 ° C., and a transparent protective film is bonded on one side is used. Obtained. The width of the obtained long polarizing plate with a single-sided transparent protective film was 1490 mm. Further, the appearance of this polarizing plate was good without damage such as scratches and cracks, despite being subjected to heat of drying and friction with the transport roll.

[Step (B)]
Subsequently, this polarizing plate with a single-sided transparent protective film was cut (slit) along the longitudinal direction according to the width of the retardation film using a slitter (Model FN25, manufactured by Nishimura Seisakusho Co., Ltd.), and 720 mm wide A polarizing plate with a single-sided transparent protective film was obtained. The appearance of the slit polarizing plate was good without damage such as scratches and cracks despite being subjected to shearing during slitting and friction with the transport roll.

[Step (D)]
After the corona treatment was performed on the retardation film at an irradiation amount of 16.8 kJ / m ² , the pressure-sensitive adhesive sheet A was bonded onto the corona-treated surface.

[Steps (C) and (E)]
Corona treatment at a dose of 16.8 kJ / m ² on the polarizing film side of the polarizing film from which the polyethylene film was peeled off and removed from the pressure-sensitive adhesive layer side of the retardation film and the polarizing plate with the single-side transparent protective film slit in the step (B). Then, the polarizing plate and the retardation film were bonded via the pressure-sensitive adhesive layer provided in the step (D) to obtain a composite polarizing plate.

  The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.

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

  The composite polarizing plate obtained by the present invention can be widely used as an optical member in various liquid crystal display devices. For example, 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 a medium- and small-sized liquid crystal display device used for the like.

Claims (12)

Retardation film comprising a stretched film having a three-layer structure of a core layer comprising a styrene resin and a skin layer comprising a (meth) acrylic resin composition containing rubber particles, which is laminated on both surfaces of the core layer. When,
A polarizing plate with a single-sided transparent protective film having a transparent protective film on one side of the polarizing film, laminated on the retardation film,
A method of manufacturing a composite polarizing plate comprising:
(A) a step of pasting a transparent protective film on one side of the polarizing film, pasting a peelable film having adhesiveness on the opposite side, and producing a polarizing plate with a single-sided transparent protective film;
(B) cutting the polarizing plate with a single-sided transparent protective film along the longitudinal direction according to the width of the retardation film;
(C) removing the peelable film from the polarizing film surface;
(D) An adhesive layer exhibiting a storage elastic modulus of 0.1 MPa or more at 80 ° C. on one side of the retardation film or the polarizing film side of the polarizing plate with the one-side transparent protective film that has undergone the step (C). Laminating steps;
(E) a step of bonding the retardation film to the polarizing film surface of the polarizing plate with the single-sided transparent protective film from which the peelable film has been removed, via the pressure-sensitive adhesive layer;
A method for producing a composite polarizing plate, comprising: Including the steps (A), (B), (C), (D) and (E) in this order,
In the said process (D), the said adhesive layer is a manufacturing method of the composite polarizing plate of Claim 1 laminated | stacked on the polarizing film surface of the said polarizing plate with a single-sided transparent protective film which passed through the said process (C). Including the steps (A), (C), (D), (B) and (E) in this order,
In the said process (D), the said adhesive layer is a manufacturing method of the composite polarizing plate of Claim 1 laminated | stacked on the polarizing film surface of the said polarizing plate with a single-sided transparent protective film which passed through the said process (C). Including the step (A), step (B), step (C) and step (E) in this order,
In the said process (D), the said adhesive layer is a manufacturing method of the composite polarizing plate of Claim 1 laminated | stacked on the single side | surface of the said retardation film.   The film thickness of the said core layer is 10-100 micrometers, The manufacturing method of the composite polarizing plate in any one of Claims 1-4 whose film thickness of the said skin layer is 10-100 micrometers.   The method for producing a composite polarizing plate according to claim 1, wherein the glass transition temperature of the core layer is 120 ° C. or higher, and the glass transition temperature of the skin layer is 120 ° C. or lower.   The composite polarizing plate according to any one of claims 1 to 6, wherein the retardation film has a width that is 10% or more smaller than the width of the polarizing plate with a single-sided transparent protective film produced in the step (A). A manufacturing method of a board.   In the said process (A), the said polarizing film and the said transparent protective film are bonded using the adhesive agent containing a polyvinyl alcohol-type resin and an epoxy resin, The composite polarized light in any one of Claims 1-7. A manufacturing method of a board.   The said process (A) WHEREIN: The said polarizing film and the said transparent protective film are bonded together using the adhesive agent which consists of a resin composition containing the epoxy resin hardened | cured by irradiation of an active energy ray or a heating. The manufacturing method of the composite polarizing plate in any one of -7.   The said epoxy resin is a manufacturing method of the composite polarizing plate of Claim 9 containing the compound which has 1 or more of epoxy groups couple | bonded with the alicyclic ring in the molecule | numerator.   The thickness of the said transparent protective film is 20-300 micrometers, The manufacturing method of the composite polarizing plate in any one of Claims 1-10.   The thickness of the said adhesive layer is 1-40 micrometers, The manufacturing method of the composite polarizing plate in any one of Claims 1-11.