JP2009093074A - Manufacturing method for polarizing plate, the polarizing plate, optical film, and image display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a polarizing plate having a polarizer capable of restraining curls from generating, even when the polarizer is reduced in thickness. <P>SOLUTION: This manufacturing method for the polarizing plate includes a process (1a) for forming a laminate laminated with a base material layer and a hydrophilic polymer layer, by drying a solution containing a hydrophilic polymer, after applying the solution containing a hydrophilic polymer on the base material layer, to form the hydrophilic polymer layer on the base material layer; a process (2) for stretching the laminate to an extensible laminate; and a process (3) for adsorbing a dichroic substance onto the hydrophilic polymer layer of the laminate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a polarizing plate. The polarizing plate obtained by the manufacturing method can form an image display device such as a liquid crystal display device (LCD), an organic EL display device, a CRT, a PDP, and an OLED alone or as an optical film obtained by laminating the polarizing plate.

  Polarizers are used in image display devices (particularly liquid crystal display devices). A polarizing plate is required to have a high transmittance and a high degree of polarization in order to provide a bright image with good color reproducibility. As such a polarizing plate, a polarizing plate in which a transparent protective film is bonded to one or both sides of the polarizer with an adhesive is used. As the transparent protective film, triacetyl cellulose having a high moisture permeability is used.

  A polarizer is conventionally manufactured by orienting a dichroic substance such as dichroic iodine or a dichroic dye on a polyvinyl alcohol film. Specifically, it can be obtained, for example, by subjecting a polyvinyl alcohol film fed from a raw fabric roll to swelling treatment, dyeing treatment, crosslinking treatment, stretching treatment, water washing treatment, drying treatment, and the like (Patent Document 1).

  In the manufacturing method described above, since a polyvinyl alcohol film of a raw fabric roll is used, there is a limit to reducing the thickness of the polarizer obtained as a result of considering the handleability of the film. Therefore, the thickness of the polarizer obtained by the above production method usually exceeds 30 μm. However, as the thickness of the polarizer increases, the shrinkage stress of the polarizer or the polarizing plate using the polarizer increases, and curling occurs when these are bonded to an image display device such as a liquid crystal display device. The problem is that light leaks. On the other hand, since the polyvinyl alcohol film of the raw fabric roll is a thin film having a thickness of about 30 μm, there is a problem of productivity such that the film is cut by a stretching process or the like.

JP 2004-341515 A

  An object of this invention is to provide the manufacturing method of the polarizing plate which has a polarizer which can suppress generation | occurrence | production of a curl, even when it makes a polarizer thin.

  The present invention also provides a polarizing plate obtained by the production method, an optical film in which the polarizing plate is laminated, and an image display such as a liquid crystal display device using the polarizing plate and the optical film. An object is to provide an apparatus.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by a method for producing a polarizing plate shown below, and have completed the present invention.

That is, the present invention provides a hydrophilic polymer layer on the base material layer by applying a solution containing the hydrophilic polymer on the base material layer and then drying the solution containing the hydrophilic polymer. Forming a laminate in which a base material layer and a hydrophilic polymer layer are laminated (1a),
A stretching step (2) for subjecting the laminate to a stretching treatment to obtain a stretched laminate, and a dyeing step (3) for adsorbing a dichroic substance to the hydrophilic polymer layer of the laminate,
The manufacturing method of the polarizing plate characterized by including this.

Further, the present invention provides a step (1b) of forming a laminate in which the base material layer and the hydrophilic polymer layer are laminated by coextrusion of the base material layer forming material and the hydrophilic polymer layer forming material,
A stretching step (2) for subjecting the laminate to a stretching treatment to obtain a stretched laminate, and a dyeing step (3) for adsorbing a dichroic substance to the hydrophilic polymer layer of the laminate,
The manufacturing method of the polarizing plate characterized by including this.

  In the method for producing a polarizing plate, a polyvinyl alcohol resin is suitable as the hydrophilic polymer forming the hydrophilic polymer layer.

  In the manufacturing method of the said polarizing plate, it is preferable that the thickness of the hydrophilic polymer layer in a extending | stretching laminated body is 0.5-30 micrometers.

  In the manufacturing method of the said polarizing plate, it can have further the bridge | crosslinking process (4) which performs a bridge | crosslinking process to the hydrophilic polymer layer of the said laminated body.

  In the manufacturing method of the polarizing plate, after the steps (1a) to (3) or the steps (1b) to (3) are performed, the hydrophilic polymer layer in the obtained stretched laminate is formed. And a step of transferring to another substrate.

  Moreover, this invention relates to the polarizing plate obtained by the said manufacturing method.

  The present invention also relates to an optical film in which at least one polarizing plate is laminated.

  Furthermore, this invention relates to the image display apparatus characterized by using the said polarizing plate or the said optical film.

  According to the method for producing a polarizing plate of the present invention, a laminate in which a hydrophilic polymer layer is laminated on a substrate layer in step (1a), or a substrate layer and a hydrophilic polymer layer in step (1b). After the laminated body is formed, the stretching process (2) is applied to the laminated body to obtain a stretched laminated body, and the dichroic substance is adsorbed to the hydrophilic polymer layer by the dyeing process (3). ing. The polarizing plate of the present invention thus obtained is a stretched laminate obtained by stretching the laminate, and the hydrophilic polymer layer in the stretched laminate serves as a polarizer by adsorbing a dichroic substance. Function. The hydrophilic polymer layer, which is the polarizer, is laminated on the base material layer and integrally forms a polarizing plate, so that a thin hydrophilic polymer layer (polarizer) can be formed. is there. As described above, the polarizer included in the polarizing plate of the present invention can be made thin and integrated with the base material layer. Therefore, even when the polarizing plate of the present invention is bonded to a liquid crystal display device, The shrinkage stress can be controlled to be small, and light leakage caused by curling of the polarizing plate can be suppressed.

  Further, as described above, in the production method of the present invention, the laminate in which the base material layer and the hydrophilic polymer layer are laminated is stretched, but the base material layer and the hydrophilic polymer layer are integrated. The polarizer (polarizing plate) obtained by the production method of the present invention is a thin layer compared to a polarizer obtained from a conventional polyvinyl alcohol film, because it is stretched as a laminate. Compared to a polarizer obtained by stretching only a conventional polyvinyl alcohol film, the film can be stretched more uniformly, can suppress the orientation of the polarizer (absorption axis variation), and the polarizer (polarizing plate) The characteristics can be improved. In addition, the polarizing plate obtained by the production method of the present invention is subjected to stretching treatment on a laminate in which a base material layer and a hydrophilic polymer layer are laminated, instead of using a thin polyvinyl alcohol film. Therefore, problems such as film cutting during the stretching treatment can be reduced, and productivity can be improved as compared with a conventional method for producing a polarizer. Moreover, since the polarizing plate obtained in the present invention has a base material layer on one side of the hydrophilic polymer layer, the base material layer can be used as it is as a transparent protective film for a polarizer. Productivity of the polarizing plate can be improved.

  In the method for producing a polarizing plate of the present invention, first, a laminate in which a base material layer and a hydrophilic polymer layer are laminated is prepared. Such a laminate is prepared by coating a solution containing a hydrophilic polymer on the base material layer, and then drying the solution containing the hydrophilic polymer to thereby improve the hydrophilic property on the base material layer. A step (1a) of forming a molecular layer to form a laminate in which the base material layer and the hydrophilic polymer layer are laminated, or a combination of the base material layer forming material and the hydrophilic polymer layer forming material. It can carry out by the process (1b) made into the laminated body by which the base material layer and the hydrophilic polymer layer were laminated | stacked by extrusion.

  What was conventionally used as a transparent protective film of a polarizer can also be used for the base material layer of the said process (1a) or the process (1b). As the material constituting the base material layer, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, stretchability and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The base material layer may be formed with a thin layer such as a primer layer (undercoat layer) in order to improve adhesion with the hydrophilic polymer layer. On the other hand, after giving the said process (1a) thru | or process (3), or the process (1b) thru | or process (3), the process of transferring the hydrophilic polymer layer in the obtained extending | stretching laminated body to another base material. In the case of applying the above, the base material layer can form a release layer in order to facilitate the release from the hydrophilic polymer layer.

  The base material layer may contain one or more arbitrary appropriate additives in addition to the above materials. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the base material layer is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, further preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a base material layer is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Moreover, as a material of the base material layer, a polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain; (B) A resin composition containing a thermoplastic resin having a substituted and / or unsubstituted phenyl and a nitrile group in the side chain. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a base material layer can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The thickness of the base material layer is particularly suitable when it is 5 to 150 μm.

  As a material for the base material layer of the present invention, it is preferable to use at least one selected from cellulose resin, polyolefin resin, cyclic polyolefin resin, and (meth) acrylic resin.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Among these, cellulose triacetate is particularly preferable. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available cellulose triacetate are trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “UZ” manufactured by Fuji Photo Film Co., Ltd. -TAC "and" KC series "manufactured by Konica. In general, these cellulose triacetates have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about ˜60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). ) And then peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating ( For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes is mentioned.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the fat substitution degree can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8. Preferably, the Rth can be reduced by controlling the acetic acid substitution degree to 1.8 to 2.7. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose resin. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Examples of the polyolefin resin include polyethylene and polypropylene. Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, product names “ARTON” manufactured by JSR Corporation, “TOPAS” manufactured by TICONA, and product names manufactured by Mitsui Chemicals, Inc. “APEL”.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. No. 146084 and the like.

  As the (meth) acrylic resin, an acrylic resin having a structural unit of unsaturated carboxylic acid alkyl ester and a structural unit of glutaric anhydride can be used. Examples of the acrylic resin include Japanese Patent Application Laid-Open Nos. 2004-70290, 2004-70296, 2004-163924, 2004-292812, 2005-314534, and 2006. No. 131898, JP 2006-206881 A, JP 2006-265532 A, JP 2006-283013 A, JP 2006-299005 A, JP 2006-335902 A, and the like. It is done.

  In addition, as the (meth) acrylic resin, a thermoplastic resin having a glutarimide unit, a (meth) acrylic ester unit, and an aromatic vinyl unit can be used. Examples of the thermoplastic resin include JP 2006-309033 A, JP 2006-317560 A, JP 2006-328329 A, JP 2006-328334 A, JP 2006-337491 A, and JP 2006. -337492, JP-A-2006-337493, JP-A-2006-337569, and the like.

  In the preparation of the laminate in the step (1a) or the step (1b), examples of the hydrophilic polymer used for forming the hydrophilic polymer layer include polyvinyl alcohol materials. Examples of the polyvinyl alcohol material include polyvinyl alcohol and derivatives thereof. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters thereof, acrylamide and the like. can give. The degree of polymerization of polyvinyl alcohol is preferably about 100 to 10,000, and more preferably 1,000 to 10,000. A saponification degree of about 80 to 100 mol% is generally used. In addition to the above, examples of the hydrophilic polymer include partially saponified ethylene / vinyl acetate copolymer, dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. As the hydrophilic polymer, it is preferable to use polyvinyl alcohol among polyvinyl alcohol materials.

  The polyvinyl alcohol resin may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer used is not particularly limited, but is preferably 20% by weight or less in the polyvinyl alcohol resin.

  The laminate prepared by the step (1a) or the step (1b) is a laminate in which the base material layer and the hydrophilic polymer layer are laminated. The thickness of the hydrophilic polymer layer in the laminate is appropriately determined according to the thickness of the hydrophilic polymer layer (stretched product) in the stretched laminate obtained by subjecting the laminate to the stretching step (2). Can be set. The thickness of the hydrophilic polymer layer (stretched product) in the stretched laminate is preferably 0.5 to 30 μm, more preferably 1 to 20 μm, from the viewpoint of using the polarizer as a thin film. 2 to 10 μm. If the thickness of the hydrophilic polymer layer (stretched product) is less than 0.5 μm, it is not preferable because the influence of the thickness variation at the time of production becomes large and the appearance is liable to occur.

  The thickness of the hydrophilic polymer layer in the laminate is the above-described thickness due to stretching or shrinkage caused by the stretching treatment. Therefore, the thickness of the hydrophilic polymer layer in the laminate is usually about 1 to 50 μm, more preferably 2 to 30 μm. In addition, the hydrophilic polymer layer in the laminate preferably has a moisture content of 1 to 20% by weight, more preferably 2 to 15% by weight, in order to subject the laminate to stretching treatment or the like.

  The thickness of the hydrophilic polymer layer and the moisture content in the laminate and the stretched laminate can be measured after the hydrophilic polymer layer is peeled off from the base material layer. The thickness is measured with a thickness gauge or the like. The moisture content was measured by cutting out the hydrophilic polymer layer peeled from the base material layer into a size of 100 × 100 mm and measuring the initial weight of this sample. Subsequently, this sample was dried at 120 ° C. for 2 hours, the dry weight was measured, and the moisture content was measured by the following formula. Moisture content (% by weight) = {(initial weight−dry weight) / initial weight} × 100. The weight was measured three times, and the average value was used.

  In the step (1a), the substrate is coated with an aqueous solution containing a hydrophilic polymer on the substrate layer, and then the solution containing the hydrophilic polymer is dried. It can be obtained by forming a hydrophilic polymer layer thereon. By such coating, the base material layer and the hydrophilic polymer layer are laminated directly via the primer layer or the release layer, or the base material layer and the hydrophilic polymer layer are directly laminated. A laminated body in which the molecular layers are integrated is obtained. The aqueous solution can be prepared by dissolving a powder of a hydrophilic polymer or a pulverized product or a cut product of a hydrophilic polymer film in appropriately heated water (hot water). Application of the aqueous solution onto the base material layer is performed by a wire bar coating method, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, or a spray method. Etc. can be selected and adopted as appropriate. When the base material layer has a primer layer or a release layer, the aqueous solution is applied directly to the primer layer or the release layer. When the base material layer does not have a primer layer, the aqueous solution is applied directly to the base material layer. The drying temperature is usually 50 to 200 ° C., preferably 80 to 150 ° C., and the drying time is usually about 5 to 30 minutes.

  On the other hand, in the step (1b), the laminate can be formed by co-extrusion of a base material layer forming material and a hydrophilic polymer layer forming material. By such coextrusion, a laminate in which the base material layer and the hydrophilic polymer layer are integrated is obtained. In the coextrusion, the material of the base material layer and the material of the hydrophilic polymer layer are charged into the coextrusion machine as a forming material of each layer, and the thickness of the base material layer and the hydrophilic polymer layer to be coextruded is It is preferable to control to be within the above range.

  In the method for producing a polarizing plate of the present invention, a dichroic substance is adsorbed on the stretching step (2) in which the laminate is subjected to a stretching treatment to form a stretched laminate, and the hydrophilic polymer layer of the laminate. A dyeing step (3) is performed. A stretched laminate is obtained by the stretching step (2). In the dyeing step (3), the hydrophilic polymer layer of the stretched laminate is dyed with a dichroic substance, and the resulting hydrophilic polymer layer is adsorbed with the dichroic substance and functions as a polarizer. To come.

  The stretching step (2) is usually performed by subjecting the laminate to uniaxial stretching. Uniaxial stretching can employ any of longitudinal stretching performed in the longitudinal direction of the laminate and transverse stretching performed in the width direction of the laminate. In the present invention, it is preferably performed by transverse stretching. In transverse stretching, the film can be contracted in the longitudinal direction while stretching in the width direction. Examples of the transverse stretching method include a fixed end uniaxial stretching method in which one end is fixed via a tenter, and a free end uniaxial stretching method in which one end is not fixed. Examples of the longitudinal stretching method include an inter-roll stretching method, a compression stretching method, and a stretching method using a tenter. The stretching process can be performed in multiple stages. The stretching treatment can be performed by performing biaxial stretching, oblique stretching, or the like.

  In addition, as the stretching treatment, either a wet stretching method or a dry stretching method can be adopted, but in the present invention, the dry stretching method can be used, and the temperature range when stretching the laminate can be set wide. Is preferable. In the dry stretching method, the stretching is usually performed in a state where the laminate is heated to about 50 to 200 ° C., preferably 80 to 180 ° C., and more preferably 100 to 160 ° C.

  In the stretching treatment, the total stretching ratio is 1.5 to 17 times the original length of the laminate. Preferably it is 1.5-10 times, More preferably, it is 1.5-8 times. In addition, the said total draw ratio means the cumulative draw ratio including the extension in those processes, when extending in processes other than an extending process process. The total draw ratio is appropriately determined in consideration of the draw ratio in other steps. When the total draw ratio is low, the orientation is insufficient and it is difficult to obtain a polarizer having high optical properties (polarization degree). On the other hand, if the total draw ratio is too high, stretch breakage is likely to occur, and the polarizer becomes too thin, which may reduce the workability in the subsequent process.

  The dyeing step (3) is performed by adsorbing a dichroic substance to the hydrophilic polymer layer of the laminate. Examples of the dichroic substance include iodine and organic dyes. Organic dyes include, for example, Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First orange S, first black, etc. can be used. One kind of these dichroic substances may be used, or two or more kinds may be used in combination.

  For example, the dyeing process is performed by immersing the laminate in a solution (dyeing solution) containing the dichroic substance. As the staining solution, a solution in which the dichroic substance is dissolved in a solvent can be used. As the solvent, water is generally used, but an organic solvent compatible with water may be further added. The concentration of the dichroic substance is preferably in the range of 0.01 to 10% by weight, more preferably in the range of 0.02 to 7% by weight, and 0.025 to 5% by weight. Is particularly preferred.

  Further, when iodine is used as the dichroic substance, it is preferable to further add an iodide because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. The addition ratio of these iodides is preferably 0.01 to 10% by weight, and more preferably 0.1 to 5% by weight in the dyeing solution. Among these, it is preferable to add potassium iodide, and the ratio (weight ratio) of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, and 1: 6 to 1:80. More preferably, it is in the range of 1: 7 to 1:70.

  The immersion time of the laminate in the dyeing solution is not particularly limited, but usually it is preferably in the range of 15 seconds to 5 minutes, more preferably 1 minute to 3 minutes. Moreover, it is preferable that it is in the range of 10-60 degreeC, and, as for the temperature of a dyeing | staining solution, it is more preferable that it exists in the range of 20-40 degreeC.

  Moreover, as a dyeing | staining process, the method of apply | coating or spraying the solution containing a dichroic substance to the said laminated body other than the method of immersing in the dyeing | staining solution as mentioned above may be sufficient, for example. Further, a dichroic substance may be mixed in advance with the solution or forming material for forming the hydrophilic polymer layer.

  In the dyeing process, the dichroic substance is oriented by adsorbing the dichroic substance to the hydrophilic polymer layer of the laminate. The dyeing step (3) can be performed before, simultaneously with, or after the stretching step (2). From the viewpoint of satisfactorily orienting the dichroic material adsorbed on the hydrophilic polymer layer, the dyeing step ( 3) is preferably performed after subjecting the laminate to the stretching step (2).

  In the manufacturing method of the polarizing plate of this invention, in addition to the said extending process (2) and dyeing | staining process (3), a bridge | crosslinking process (4) can be given. The crosslinking treatment can be performed, for example, by immersing the laminate in a solution containing a crosslinking agent (crosslinking solution). A conventionally known substance can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. One kind of these may be used, or two or more kinds may be used in combination.

  As the crosslinking solution, a solution obtained by dissolving the crosslinking agent in a solvent can be used. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. The concentration of the crosslinking agent in the solution is not limited to this, but is preferably in the range of 1 to 10% by weight, and more preferably 2 to 6% by weight.

  Iodide may be added to the crosslinking solution from the viewpoint that uniform characteristics in the plane of the polarizer can be obtained. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. The content is 0.05 to 15% by weight, more preferably 0.5 to 8% by weight.

  The immersion time of the laminate in the crosslinking solution is usually preferably from 15 seconds to 5 minutes, and more preferably from 30 seconds to 3 minutes. Moreover, it is preferable that the temperature of a bridge | crosslinking solution exists in the range of 10-60 degreeC, and it is more preferable that it exists in the range of 20-50 degreeC.

  Furthermore, the crosslinking step (4) can also be performed using a method of coating or spraying the crosslinking solution, similarly to the dyeing step (3). In the cross-linking step (4), the cross-linking step (4) and the dyeing step (3) can be simultaneously performed by blending the cross-linking agent into the dyeing solution. Moreover, you may perform a bridge | crosslinking process (4) with an extending | stretching process (2).

  In addition to the above treatment, the polarizing plate of the present invention can be subjected to metal ion treatment. The metal ion treatment is performed by immersing the laminate in an aqueous solution containing a metal salt. Various metal ions can be contained in the hydrophilic polymer layer of the laminate by metal ion treatment.

  As metal ions, metal ions of transition metals such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, and iron are particularly preferably used in terms of color tone adjustment and durability. Among these metal ions, zinc ions are preferable from the viewpoints of color tone adjustment and heat resistance. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide, zinc sulfate, and zinc acetate.

  A metal salt solution is used for the metal ion impregnation treatment. The concentration of zinc ions in the metal salt solution is about 0.1 to 10% by weight, preferably 0.3 to 7% by weight. Further, as the metal circle solution, it is preferable to use an aqueous solution containing an iodide such as potassium iodide because it is easy to impregnate metal ions. The iodide concentration in the metal salt solution is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% by weight.

  In the metal ion impregnation treatment, the temperature of the metal salt solution is usually about 15 to 85 ° C, preferably 25 to 70 ° C. The immersion time is usually about 1 to 120 seconds, preferably 3 to 90 seconds. The stage of the metal ion impregnation treatment is not particularly limited, and may be performed simultaneously with the dyeing step (3) and / or the crosslinking step (4) in the presence of a zinc salt in the dyeing solution and / or the crosslinking solution. It can also be performed simultaneously with the stretching step (2).

  After the treatment, the obtained stretched laminate can be washed. The washing treatment can be performed with an iodide solution such as potassium iodide. The iodide concentration in the iodide solution is usually in the range of about 0.5 to 10% by weight, more preferably 0.5 to 8% by weight, and further 1 to 6% by weight.

  In the washing treatment with an iodide solution, the treatment temperature is usually about 15 to 60 ° C, preferably 25 to 40 ° C. The immersion time is usually about 1 to 120 seconds, preferably 3 to 90 seconds. The stage of the washing treatment with the iodide solution is not particularly limited as long as it is before the drying treatment.

  Further, as a cleaning process, a water cleaning process can be performed. The water washing treatment can usually be performed by immersing the stretched laminate in pure water such as ion exchange water or distilled water. The water washing temperature is usually in the range of 5 to 50 ° C, preferably 10 to 45 ° C, more preferably 15 to 40 ° C. The immersion time is usually about 10 to 300 seconds, preferably about 20 to 240 seconds.

  The water washing treatment may be a combination of a washing treatment with an iodide solution and a water washing treatment, and a solution appropriately mixed with a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, or propanol may be used.

  After the washing process, a drying process can be performed. Arbitrary appropriate methods (For example, natural drying, ventilation drying, heat drying) can be employ | adopted for a drying process. For example, the drying temperature in the case of heat drying is usually about 20 to 80 ° C., and the drying time is usually about 1 to 10 minutes. A polarizer is obtained as described above.

  The polarizer (hydrophilic polymer layer) in the polarizing plate (stretched laminate) used in the present invention preferably has a moisture content of 20% by weight or less, more preferably 0 to 15% by weight, and still more preferably 1 to 15%. % By weight. When the moisture content is larger than 20% by weight, the dimensional change of the obtained polarizing plate becomes large, which may cause a problem that the dimensional change at high temperature or high temperature and high humidity becomes large.

  The polarizing plate (stretched laminate) obtained by the production method of the present invention has a base material layer on one side of a hydrophilic polymer layer (polarizer). A base material layer can be used as it is as a transparent protective film of a polarizing plate. On the other hand, a transparent protective film can be bonded to the side without the base material layer in the hydrophilic polymer layer. Moreover, after peeling a hydrophilic polymer layer from a base material layer, a transparent protective film can be bonded together on the both sides of the said hydrophilic polymer layer. Further, the hydrophilic polymer layer in the obtained stretched laminate can be transferred to another substrate. The transfer can be carried out by peeling off the base material layer after pasting another base material (for example, a transparent protective film) to the hydrophilic polymer layer. After peeling off, the hydrophilic polymer layer can be bonded to another substrate.

  As the transparent protective film, the same materials as those exemplified as the base material layer can be used. Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a hydrophilic polymer layer (polarizer), a transparent protective film (including a base material layer) made of the same polymer material may be used on the front and back sides, different polymer materials, etc. You may use the transparent protective film which consists of.

  As the transparent protective film, one having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm is usually used. The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ]. In addition, it is preferable that a transparent protective film has as little color as possible. A protective film having a thickness direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the transparent protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  On the other hand, as the transparent protective film, a phase difference plate having a phase difference with a front phase difference of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate functions also as a transparent protective film, so that the thickness can be reduced.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyester, polyetherketone, polyamideimide, polyesterimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or a binary of these , Ternary copolymers, graft copolymers, blends Etc., and the like. These polymer materials become an oriented product (stretched film) by stretching or the like. Among the polymer materials, polyamide, polyimide, polyester, polyetherketone, polyamideimide, polyesterimide, and the like are nx> ny> nz (biaxial film), nx = ny> nz (non-liquid crystalline material). Negative C plate) can be formed.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. . Specific examples of the main chain type liquid crystal polymer include a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystal polymers can be prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of liquid crystal layers and compensation of viewing angle, etc. It may be one in which retardation plates are stacked and optical characteristics such as retardation are controlled.

  The retardation plate has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. What is satisfactory is selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

  For example, in a phase difference plate that satisfies nx> ny> nz, a surface plate having a front phase difference of 40 to 100 nm, a thickness direction phase difference of 100 to 320 nm, and an Nz coefficient of 1.8 to 4.5 is used. Is preferred. For example, in a retardation plate (positive A plate) that satisfies nx> ny = nz, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, for a retardation plate (negative A plate) that satisfies nz = nx> ny, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, in a retardation plate satisfying nx> nz> ny, it is preferable to use a retardation plate having a front phase difference of 150 to 300 nm and an Nz coefficient exceeding 0 to 0.7. Further, as described above, for example, nx = ny> nz, nz> nx> ny, or nz> nx = ny can be used.

  The transparent protective film can be appropriately selected according to the applied liquid crystal display device. For example, in the case of VA (including Vertical Alignment, MVA, and PVA), it is desirable that at least one of the polarizing plates (cell side) has a retardation. As specific phase differences, it is desirable that Re = 0 to 240 nm and Rth = 0 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> ny> nz, nx> nz> ny, and nx = ny> nz are desirable. When polarizing plates are used above and below the liquid crystal cell, both the upper and lower sides of the liquid crystal cell may have a phase difference, or any one of the upper and lower transparent protective films may have a phase difference.

  For example, in the case of IPS (including In-Plane Switching, FFS), both cases where the transparent protective film on one side of the polarizing plate has a phase difference and does not have a phase difference can be used. For example, when there is no phase difference, it is desirable that the liquid crystal cell does not have a phase difference both above and below (cell side). When the liquid crystal cell has a phase difference, it is desirable that the liquid crystal cell has a phase difference on both the upper and lower sides. When there is no phase difference, or when the A plate is on the upper side and the positive C plate is on the lower side). When it has a phase difference, it is desirable that Re = −500 to 500 nm and Rth = −500 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> nz> ny, nz> nx = ny, and nz> nx> ny are desirable.

  In addition, the film which has the said phase difference can be separately bonded to the transparent protective film which does not have a phase difference, and the said function can be provided.

  The transparent protective film is usually bonded to the hydrophilic polymer layer (polarizer) with an adhesive, but a surface modification treatment may be performed before applying the adhesive. Specific examples of the treatment include corona treatment, plasma treatment, primer treatment, saponification treatment, and treatment with a coupling agent.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. In addition, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer (for example, a backlight-side diffusion plate).

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

The hard coat layer is preferably a hard coat layer having a pencil hardness of 4H or higher. Examples of the material of the hard coat layer include those formed using a hard coat layer forming resin containing the following component (A), component (B) and component (C). Such a hard coat layer is described in Japanese Patent Application No. 2006-239137 by the present applicant.
(A) component: At least one of urethane acrylate and urethane methacrylate.
Component (B): At least one of polyol acrylate and polyol methacrylate (C) Component: a polymer or copolymer formed from at least one of the following (C1) and (C2), or a mixed polymer of the above polymer and copolymer.
(C1): An alkyl acrylate having an alkyl group having at least one of a hydroxyl group and an acryloyl group.
(C2): An alkyl methacrylate having an alkyl group having at least one of a hydroxyl group and an acryloyl group.

  An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and water-based polyesters. The said adhesive agent is normally used as an adhesive agent which consists of aqueous solution, and contains 0.5 to 60 weight% of solid content normally. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive. The electron beam curable polarizing plate adhesive exhibits suitable adhesion to the various transparent protective films. In particular, it exhibits good adhesion even with respect to acrylic resins for which it was difficult to satisfy the adhesion. The adhesive used in the present invention can contain a metal compound filler.

  The polarizing plate of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or more optical layers that may be used can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, an elliptical polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on the polarizing plate. A wide viewing angle polarizing plate obtained by further laminating a viewing angle compensation film on a plate or a polarizing plate, or a polarizing plate obtained by further laminating a brightness enhancement film on the polarizing plate is preferable.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. Moreover, the transparent protective film contains fine particles so as to have a surface fine concavo-convex structure and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. The transparent protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it, and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by transparent the metal by an appropriate method such as a vapor deposition method such as a vacuum vapor deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of directly attaching to the surface of the protective layer.

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate or the like is used to prevent the reflectance from being lowered due to oxidation, and thus to maintain the initial reflectance for a long time. In addition, it is more preferable to avoid a separate attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function. Specific examples of the retardation plate include a birefringent film obtained by stretching a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate, and polyamide. And an alignment film of a liquid crystal polymer, and a liquid crystal polymer alignment layer supported by a film. The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of the liquid crystal layer, viewing angle, and the like. What laminated | stacked the phase difference plate and controlled optical characteristics, such as phase difference, etc. may be used.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflection type) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. As such a viewing angle compensation phase difference plate, for example, a retardation film, an alignment film such as a liquid crystal polymer, or an alignment layer such as a liquid crystal polymer supported on a transparent substrate is used. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  Also, from the viewpoint of achieving a wide viewing angle with good visibility, an optically compensated phase difference in which a liquid crystal polymer alignment layer, in particular an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetylcellulose film. A plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things such as a thing can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer. However, in order to suppress absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for light-color light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation layer, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, the cholesteric liquid crystal layer can also be obtained by reflecting circularly polarized light in a wide wavelength range such as a visible light region by combining two or more layers having different reflection wavelengths and having an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

  An adhesive layer for adhering to other members such as a liquid crystal cell may be provided on the polarizing plate described above or an optical film in which at least one polarizing plate is laminated. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  Attachment of the adhesive layer to one or both sides of the polarizing plate or the optical film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and this is applied to a polarizing plate or an optical film. The method of moving up is mentioned.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing plate or an optical film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 40 μm, preferably 5 to 30 μm, particularly preferably 10 to 25 μm. If it is thinner than 1 μm, the durability will be poor, and if it is thicker than 40 μm, it will be liable to float or peel off due to foaming, resulting in poor appearance.

  On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In order to improve the adhesion between the polarizing plate and the pressure-sensitive adhesive layer, an anchor layer can be provided between the layers.

  As the material for forming the anchor layer, an anchor agent selected from polyurethane, polyester, and polymers containing an amino group in the molecule is preferably used, and polymers containing an amino group in the molecule are particularly preferred. . Polymers containing an amino group in the molecule ensure good adhesion because the amino group in the molecule exhibits an interaction such as a reaction or ionic interaction with the carboxyl group in the pressure-sensitive adhesive.

  Examples of polymers containing an amino group in the molecule include polymers of amino-containing group-containing monomers such as polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, dimethylaminoethyl acrylate, and the like.

  An antistatic agent may be added to the anchor layer in order to impart antistatic properties. Antistatic agents for imparting antistatic properties include ionic surfactant systems, conductive polymer systems such as polyaniline, polythiophene, polypyrrole, and polyquinoxaline, metal oxide systems such as tin oxide, antimony oxide, and indium oxide. In particular, from the viewpoint of optical properties, appearance, antistatic effect, and antistatic effect heating and stability during humidification, a conductive polymer system is preferably used. Among these, water-soluble conductive polymers such as polyaniline and polythiophene or water-dispersible conductive polymers are particularly preferably used. When a water-soluble conductive polymer or a water-dispersible conductive polymer is used as a material for forming the antistatic layer, it is possible to suppress deterioration of the optical film substrate due to an organic solvent during coating.

  In the present invention, the polarizer, the transparent protective film, the optical film, and the like that form the polarizing plate described above, and each layer such as an adhesive layer include, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, and a cyanoacrylate. It may be a compound having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a compound based on nickel or a nickel complex salt compound.

  The polarizing plate or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate or optical film by invention, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the polarizing plate or optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing plate or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

<Measurement of phase difference value>
The phase difference value was measured using a phase difference meter based on the parallel Nicol rotation method (product name “KOBRA21-ADH” manufactured by Oji Scientific Instruments Co., Ltd.), nx, ny. , Nz, and film thickness (d), front phase difference Re, thickness direction phase difference Rth, and Nz were determined. [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ].

Example 1
(Preparation of aqueous solution containing hydrophilic polymer)
Kuraray Co., Ltd. polyvinyl alcohol film (average polymerization degree 2400, saponification degree 99 mol%, trade name: VF-PS2400) is cut into small pieces of 5 mm or less on one side and dissolved in 95 ° C hot water Then, a polyvinyl alcohol aqueous solution having a concentration of 10% by weight was prepared.

(Creation of laminate: formation of hydrophilic polymer layer)
As the base material layer, an acrylic resin film (lactonized polymethyl methacrylate film, Re = 2 nm, Rth = 0 nm) having a thickness of 40 μm was used. The acrylic resin film is a (meth) acrylic resin having a lactone ring structure [weight ratio of copolymerization monomer: methyl methacrylate / 2- (hydroxymethyl) methyl acrylate = 8/2; lactone cyclization rate of about 100 %] A mixture of 90 parts by weight and 10 parts by weight of acrylonitrile-styrene (AS) resin {Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.} (manufactured by Nippon Shokubai Co., Ltd.) was melt-extruded, and the length was 2.0. It was obtained by stretching at a magnification of 2.4 times and laterally.

  After applying the polyvinyl alcohol aqueous solution to the acrylic resin film, it was dried at 120 ° C. for 10 minutes to obtain a laminate having a 5 μm thick polyvinyl alcohol coating film formed as a hydrophilic polymer layer.

(Extension process)
The above laminate was stretched up to 5 times in the width direction by free end uniaxial stretching using a tenter apparatus under heating at 143 ° C. to obtain a stretched laminate. At this time, the distance between chucks was 100 mm, and the stretching speed was 2 mm / sec. After the stretching treatment, the thickness of the polyvinyl alcohol coating film was 2 μm.

(Dyeing process)
Next, the stretched laminate was immersed in an iodine solution (weight ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Thereafter, drying was performed at 60 ° C. for 4 minutes to obtain a polarizing plate. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 2 μm.

Example 2
In Example 1, the same operation as Example 1 was performed except having changed the draw ratio in the extending | stretching process into 3 times, and the polarizing plate was obtained. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 3 μm.

Example 3
In Example 1, a polarizing plate was obtained by performing the same operation as in Example 1 except that a polypropylene film having a thickness of 50 μm was used as the base material layer and the stretching ratio in the stretching treatment was changed to 2.4 times. It was. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 3 μm.

Example 4
In Example 1, a 50 μm-thick norbornene resin film (manufactured by JSR Corporation, trade name: Arton Film) was used as the base material layer, and the thickness of the polyvinyl alcohol coating film formed as the hydrophilic polymer layer was A polarizing plate was obtained by performing the same operation as in Example 1 except that the thickness was changed to 15 μm and the stretching ratio in the stretching treatment was changed to 1.5 times. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 3 μm.

Example 5
In Example 1, a 50 μm-thick norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name: ZEONOR film) was used as the base material layer, and the thickness of the polyvinyl alcohol coating film formed as the hydrophilic polymer layer Was changed to 15 μm, and the same operation as in Example 1 was performed except that the stretching ratio in the stretching treatment was changed to 3.3 times to obtain a polarizing plate. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 3 μm.

Example 6
In Example 1, after changing the draw ratio in the drawing treatment to 3 times and performing the dyeing treatment, the aqueous solution containing 3 wt% boric acid and 3 wt% potassium iodide at 30 ° C. After performing the immersion process for 2 seconds, the same operation as Example 1 was performed except having dried at 60 degreeC for 4 minute (s), and the polarizing plate was obtained. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 3 μm.

Example 7
In Example 1, the stretching process was performed by uniaxial stretching at a fixed end (in a state where the width direction was chucked) using a tenter apparatus under heating at 143 ° C., and the stretching ratio was stretched to 2.2 times in the width direction. Except that it was a stretched laminate (at this time, the distance between chucks was 100 mm and the stretching speed was 2 mm / sec. The thickness of the polyvinyl alcohol coating film after the stretching treatment was 2 μm). Thus, a polarizing plate was obtained. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 2 μm.

Example 8
In Example 7, the same operation as in Example 7 was performed except that the stretching ratio in the stretching treatment was changed to 2.4 times to obtain a polarizing plate. The thickness of the polyvinyl alcohol coating film in the obtained polarizing plate (stretched laminate) was 2 μm.

[Evaluation]
The following evaluation was performed about the polarizing plate obtained in the Example. In addition, as for the polarizing plate obtained in the Example, on one side (polarizer layer surface: surface of polyvinyl alcohol coating film), as a transparent protective film, a 40 μm-thick triacetyl cellulose film is coated with a polyvinyl alcohol adhesive. The laminated ones were used for evaluation. The results are shown in Table 1.

(Optical characteristics measurement method)
The optical properties of the obtained polarizing plate were measured with a spectrophotometer with an integrating sphere (V7100 manufactured by JASCO Corporation). The transmittance for each linearly polarized light was measured with 100% of the completely polarized light obtained through the Grantera-prism polarizer. The single transmittance (Ts), parallel transmittance (H ₀ ), and orthogonal transmittance (H ₉₀ ) were measured at a wavelength of 550 nm, and the degree of polarization (P) was determined from the values by the following formula. Note that these transmittances are Y values obtained by correcting the visibility with a J1SZ 8701 2 degree visual field (C light source).
Polarization degree (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100
The single transmittance (Ts) is 40% or more, and the degree of polarization is 99% or more, which are set as target values applicable to the liquid crystal display device. The polarizing plates obtained in the examples satisfied the single transmittance (Ts) and the target values of the degree of polarization.

  In the polarizing plates obtained in the examples, although the polarizer (polyvinyl alcohol coating film) was thin, the occurrence of curling was suppressed. Further, no defects such as cutting were observed in the stretching process.

Claims (9)

After coating the solution containing the hydrophilic polymer on the base material layer, by drying the solution containing the hydrophilic polymer, the hydrophilic polymer layer is formed on the base material layer, A step (1a) of forming a laminate in which a base material layer and a hydrophilic polymer layer are laminated;
A stretching step (2) for subjecting the laminate to a stretching treatment to obtain a stretched laminate, and a dyeing step (3) for adsorbing a dichroic substance to the hydrophilic polymer layer of the laminate,
The manufacturing method of the polarizing plate characterized by including. A step of forming a laminate in which the base material layer and the hydrophilic polymer layer are laminated by coextrusion of the base material layer forming material and the hydrophilic polymer layer forming material (1b);
A stretching step (2) for subjecting the laminate to a stretching treatment to obtain a stretched laminate, and a dyeing step (3) for adsorbing a dichroic substance to the hydrophilic polymer layer of the laminate,
The manufacturing method of the polarizing plate characterized by including.   The method for producing a polarizing plate according to claim 1 or 2, wherein the hydrophilic polymer forming the hydrophilic polymer layer is a polyvinyl alcohol resin.   The method for producing a polarizing plate according to claim 1, wherein the hydrophilic polymer layer in the stretched laminate has a thickness of 0.5 to 30 μm.   Furthermore, it has the process (4) which performs a crosslinking process to the hydrophilic polymer layer of the said laminated body, The manufacturing method of the polarizing plate in any one of Claims 1-4 characterized by the above-mentioned.   After performing the steps (1a) to (3) or the steps (1b) to (3), the step of transferring the hydrophilic polymer layer in the obtained stretched laminate to another substrate is included. The manufacturing method of the polarizing plate in any one of Claims 1-5 characterized by the above-mentioned.   The polarizing plate obtained by the manufacturing method in any one of Claims 1-6.   An optical film, wherein at least one polarizing plate according to claim 7 is laminated.   An image display device, wherein the polarizing plate according to claim 7 or the optical film according to claim 8 is used.